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| versions
list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.3430 | Micha{\l} Stukow | Michal Stukow | Commensurability of geometric subgroups of mapping class groups | null | Geometriae Dedicata 143 (2009), 117-142 | 10.1007/s10711-009-9377-y | null | math.GT math.GR | null | Let M be a surface (possibly nonorientable) with punctures and/or boundary
components. The paper is a study of ``geometric subgroups'' of the mapping
class group of M, that is subgroups corresponding to inclusions of subsurfaces
(possibly disconnected). We characterise the subsurfaces which lead to
virtually abelian geometric subgroups. We provide algebraic and geometric
conditions under which two geometric subgroups are commensurable. We also
describe the commensurator of a geometric subgroup in terms of the stabiliser
of the underlying subsurface. Finally, we show some applications of our
analysis to the theory of irreducible unitary representations of mapping class
groups.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:24:22 GMT"
}
] | 2014-02-18T00:00:00 | [
[
"Stukow",
"Michal",
""
]
] |
0707.3431 | Jens Anders Gesser | J. Ambjorn and J. A. Gesser | The nature of ZZ branes | 10 pages, footnote added | Phys.Lett.B659:718-722,2008 | 10.1016/j.physletb.2007.12.003 | null | hep-th | null | In minimal non-critical string theory we show that the principal (r,s) ZZ
brane can be viewed as the basic (1,1) ZZ boundary state tensored with the
(r,s) Cardy boundary state. In this sense there exists only one ZZ boundary
state, the basic (1,1) boundary state.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:26:18 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Dec 2007 19:49:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ambjorn",
"J.",
""
],
[
"Gesser",
"J. A.",
""
]
] |
0707.3432 | Gudlaugur J\'ohannesson | Gu{\dh}laugur J\'ohannesson, Gunnlaugur Bj\"ornsson, and Einar H.
Gudmundsson | Luminosity Functions of Gamma-Ray Burst Afterglows | 5 pages, 4 figures; accepted for publication in A&A | null | 10.1051/0004-6361:20078028 | null | astro-ph | null | Aims: Use the standard fireball model to create virtual populations of
gamma-ray burst afterglows and study their luminosity functions.
Methods: We randomly vary the parameters of the standard fireball model to
create virtual populations of afterglows. We use the luminosity of each burst
at an observer's time of 1 day to create a luminosity function and compare our
results with available observational data to assess the internal consistency of
the standard fireball model.
Results: We show that the luminosity functions can be described by a function
similar to a log normal distribution with an exponential cutoff. The function
parameters are frequency dependent but not very dependent on the model
parameter distributions used to create the virtual populations. Comparison with
observations shows that while there is good general agreement with the data, it
is difficult to explain simultaneously the X-ray and optical data. Possible
reasons for this are discussed and the most likely one is that the standard
fireball model is incomplete and that decoupling of the X-ray and optical
emission mechanism may be needed.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:40:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jóhannesson",
"Guðlaugur",
""
],
[
"Björnsson",
"Gunnlaugur",
""
],
[
"Gudmundsson",
"Einar H.",
""
]
] |
0707.3433 | Odesskii Alexander | E. V. Ferapontov and A. V. Odesskii | Integrable Lagrangians and modular forms | 17 pages, latex | null | null | null | nlin.SI hep-th math.AG math.DG math.NT | null | We investigate non-degenerate Lagrangians of the form
$$
\int f(u_x, u_y, u_t) dx dy dt
$$ such that the corresponding Euler-Lagrange equations
$
(f_{u_x})_x+ (f_{u_y})_y+ (f_{u_t})_t=0
$ are integrable by the method of hydrodynamic reductions. We demonstrate
that the integrability conditions, which constitute an involutive
over-determined system of fourth order PDEs for the Lagrangian density f, are
invariant under a 20-parameter group of Lie-point symmetries whose action on
the moduli space of integrable Lagrangians has an open orbit. The density of
the `master-Lagrangian' corresponding to this orbit is shown to be a modular
form in three variables defined on a complex hyperbolic ball. We demonstrate
how the knowledge of the symmetry group allows one to linearise the
integrability conditions.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:52:21 GMT"
},
{
"version": "v2",
"created": "Wed, 28 Nov 2007 16:27:39 GMT"
}
] | 2007-11-28T00:00:00 | [
[
"Ferapontov",
"E. V.",
""
],
[
"Odesskii",
"A. V.",
""
]
] |
0707.3434 | Steven J. van Enk | S.J. van Enk and G. Nienhuis | Photons in polychromatic rotating modes | enormously expanded: 12 pages, 3 figures; a new, more informative,
but less elegant title, especially designed for Phys. Rev. A | Phys. Rev. A 76, 053825 (2007) | 10.1103/PhysRevA.76.053825 | null | quant-ph | null | We propose a quantum theory of rotating light beams and study some of its
properties. Such beams are polychromatic and have either a slowly rotating
polarization or a slowly rotating transverse mode pattern. We show there are,
for both cases, three different natural types of modes that qualify as
rotating, one of which is a new type not previously considered. We discuss
differences between these three types of rotating modes on the one hand and
non-rotating modes as viewed from a rotating frame of reference on the other.
We present various examples illustrating the possible use of rotating photons,
mostly for quantum information processing purposes. We introduce in this
context a rotating version of the two-photon singlet state.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:47:40 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Jul 2007 21:58:11 GMT"
},
{
"version": "v3",
"created": "Tue, 18 Sep 2007 21:45:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"van Enk",
"S. J.",
""
],
[
"Nienhuis",
"G.",
""
]
] |
0707.3435 | Joseph Y. Halpern | Joseph Y. Halpern and Sabina Petride | A Knowledge-Based Analysis of Global Function Computation | null | null | null | null | cs.DC cs.LO | null | Consider a distributed system N in which each agent has an input value and
each communication link has a weight. Given a global function, that is, a
function f whose value depends on the whole network, the goal is for every
agent to eventually compute the value f(N). We call this problem global
function computation. Various solutions for instances of this problem, such as
Boolean function computation, leader election, (minimum) spanning tree
construction, and network determination, have been proposed, each under
particular assumptions about what processors know about the system and how this
knowledge can be acquired. We give a necessary and sufficient condition for the
problem to be solvable that generalizes a number of well-known results. We then
provide a knowledge-based (kb) program (like those of Fagin, Halpern, Moses,
and Vardi) that solves global function computation whenever possible. Finally,
we improve the message overhead inherent in our initial kb program by giving a
counterfactual belief-based program that also solves the global function
computation whenever possible, but where agents send messages only when they
believe it is necessary to do so. The latter program is shown to be implemented
by a number of well-known algorithms for solving leader election.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 18:49:28 GMT"
}
] | 2007-08-08T00:00:00 | [
[
"Halpern",
"Joseph Y.",
""
],
[
"Petride",
"Sabina",
""
]
] |
0707.3436 | Luis Ho | Luis C. Ho (The Observatories of the Carnegie Institution of
Washington) | The CO Tully-Fisher Relation and Implications for the Host Galaxies of
High-Redshift Quasars | To appear in ApJ; 10 pages | null | 10.1086/521917 | null | astro-ph | null | The integrated line width derived from CO spectroscopy provides a powerful
tool to study the internal kinematics of extragalactic objects, including
quasars at high redshift, provided that the observed line width can be properly
translated to more conventionally used kinematical parameters of galaxies. We
show, through construction of a K-band CO Tully-Fisher relation for nearby
galaxies spanning a wide range in infrared luminosity, that the CO line width
measured at 20% of the peak intensity, when corrected for inclination and other
effects, successfully recovers the maximum rotation velocity of the disk. The
line width at 50% of the peak intensity performs much more poorly, in large
part because CO lines have a wide range of profiles, which are shown to vary
systematically with infrared luminosity. We present a practical prescription
for converting observed CO line widths into the stellar velocity dispersion of
the bulge (sigma), and then apply it to a sample of low-redshift (z < 0.2) and
high-redshift (1.4 < z < 6.4) quasars to study their host galaxies. Nearby
quasars roughly fall on the correlation between black hole mass and bulge
stellar velocity dispersion established for inactive galaxies, but the host
galaxies of the high-z quasars systematically deviate from the local M_BH-sigma
relation. At a given sigma, high-z quasars have black hole masses larger by a
factor of 4 relative to local galaxies, suggesting that early in the life-cycle
of galaxies the development of the bulge lags behind the growth of the central
black hole. An alternative explanation for these observations, which currently
cannot be ruled out rigorously, is that high-redshift quasars are
preferentially viewed at face-on orientations.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 14:07:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ho",
"Luis C.",
"",
"The Observatories of the Carnegie Institution of\n Washington"
]
] |
0707.3437 | Xi Yin | Davide Gaiotto, Xi Yin | Genus Two Partition Functions of Extremal Conformal Field Theories | 14 pages | JHEP 0708:029,2007 | 10.1088/1126-6708/2007/08/029 | null | hep-th | null | Recently Witten conjectured the existence of a family of "extremal" conformal
field theories (ECFTs) of central charge c=24k, which are supposed to be dual
to three-dimensional pure quantum gravity in AdS3. Assuming their existence, we
determine explicitly the genus two partition functions of k=2 and k=3 ECFTs,
using modular invariance and the behavior of the partition function in
degenerating limits of the Riemann surface. The result passes highly nontrivial
tests and in particular provides a piece of evidence for the existence of the
k=3 ECFT. We also argue that the genus two partition function of ECFTs with
k<11 are uniquely fixed (if they exist).
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:07:21 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Gaiotto",
"Davide",
""
],
[
"Yin",
"Xi",
""
]
] |
0707.3438 | Emiliano De Simone | E. De Simone, A. Kupiainen | KAM Theorem and Renormalization Group | 17 pages, no figures | null | null | null | math-ph math.MP | null | We give an elementary proof of the analytic KAM theorem by reducing it to a
Picard iteration of a PDE with quadratic nonlinearity, the so called Polchinski
renormalization group equation studied in quantum field theory.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:37:58 GMT"
}
] | 2007-07-24T00:00:00 | [
[
"De Simone",
"E.",
""
],
[
"Kupiainen",
"A.",
""
]
] |
0707.3439 | Vincenzo Cirigliano | Vincenzo Cirigliano and Ignasi Rosell | The Standard Model prediction for R_{e/mu}^{(pi,K)} | 4 pages, 1 figure, 2 tables | Phys.Rev.Lett.99:231801,2007 | 10.1103/PhysRevLett.99.231801 | LAUR-07-3194 | hep-ph | null | We study the ratios R_{e/mu}^{(P)} = Gamma(P -> e nu [gamma])/Gamma(P -> mu
nu [gamma]) (P=pi,K) in Chiral Perturbation Theory to order e^2 p^4. We
complement the two-loop effective theory results with a matching calculation of
the counterterm, finding R_{e/mu}^{(pi)} = (1.2352 \pm 0.0001)*10^(-4) and
R_{e/mu}^{(K)} = (2.477 \pm 0.001)*10^(-5).
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:43:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cirigliano",
"Vincenzo",
""
],
[
"Rosell",
"Ignasi",
""
]
] |
0707.3440 | Justin Howell | Justin H. Howell, Joseph M. Mazzarella, Ben H. P. Chan, Steven Lord,
Jason A. Surace, David T. Frayer, P. N. Appleton, Lee Armus, Aaron S. Evans,
Greg Bothun, Catherine M. Ishida, Dong-Chan Kim, Joseph B. Jensen, Barry F.
Madore, David B. Sanders, Bernhard Schulz, Tatjana Vavilkin, Sylvain
Veilleux, and Kevin Xu | Tracing PAHs and Warm Dust Emission in the Seyfert Galaxy NGC 1068 | 20 pages, 11 figures; AJ, accepted; full resolution version available
at http://spider.ipac.caltech.edu/staff/jhhowell/astro/howelln1068.pdf | Astron.J.134:2086-2097,2007 | 10.1086/521821 | null | astro-ph | null | We present a study of the nearby Seyfert galaxy NGC 1068 using mid- and far-
infrared data acquired with the IRAC, IRS, and MIPS instruments aboard the
Spitzer Space Telescope. The images show extensive 8 um and 24 um emission
coinciding with star formation in the inner spiral approximately 15" (1 kpc)
from the nucleus, and a bright complex of star formation 47" (3 kpc) SW of the
nucleus. The brightest 8 um PAH emission regions coincide remarkably well with
knots observed in an Halpha image. Strong PAH features at 6.2, 7.7, 8.6, and
11.3 um are detected in IRS spectra measured at numerous locations inside,
within, and outside the inner spiral. The IRAC colors and IRS spectra of these
regions rule out dust heated by the AGN as the primary emission source; the
SEDs are dominated by starlight and PAH emission. The equivalent widths and
flux ratios of the PAH features in the inner spiral are generally consistent
with conditions in a typical spiral galaxy ISM. Interior to the inner spiral,
the influence of the AGN on the ISM is evident via PAH flux ratios indicative
of a higher ionization parameter and a significantly smaller mean equivalent
width than observed in the inner spiral. The brightest 8 and 24 um emission
peaks in the disk of the galaxy, even at distances beyond the inner spiral, are
located within the ionization cones traced by [O III]/Hbeta, and they are also
remarkably well aligned with the axis of the radio jets. Although it is
possible that radiation from the AGN may directly enhance PAH excitation or
trigger the formation of OB stars that subsequently excite PAH emission at
these locations in the inner spiral, the orientation of collimated radiation
from the AGN and star formation knots in the inner spiral could be
coincidental. (abridged)
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:48:17 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"Howell",
"Justin H.",
""
],
[
"Mazzarella",
"Joseph M.",
""
],
[
"Chan",
"Ben H. P.",
""
],
[
"Lord",
"Steven",
""
],
[
"Surace",
"Jason A.",
""
],
[
"Frayer",
"David T.",
""
],
[
"Appleton",
"P. N.",
""
],
[
"Armus",
"Lee",
""
],
[
"Evans",
"Aaron S.",
""
],
[
"Bothun",
"Greg",
""
],
[
"Ishida",
"Catherine M.",
""
],
[
"Kim",
"Dong-Chan",
""
],
[
"Jensen",
"Joseph B.",
""
],
[
"Madore",
"Barry F.",
""
],
[
"Sanders",
"David B.",
""
],
[
"Schulz",
"Bernhard",
""
],
[
"Vavilkin",
"Tatjana",
""
],
[
"Veilleux",
"Sylvain",
""
],
[
"Xu",
"Kevin",
""
]
] |
0707.3441 | Alexandre Oliveira | A. S. Oliveira, J. E. Steiner | CAL 87 - an evolved wind-driven supersoft X-ray binary | Four pages, accepted to be published as a Letter in A&A | null | 10.1051/0004-6361:20077971 | null | astro-ph | null | Compact binary supersoft X-ray sources (CBSS) are explained as being
associated with hydrostatic nuclear burning on the surface of a white dwarf
with high accretion rate. This high mass transfer rate has been suggested to be
caused by dynamical instability, expected when the donor star is more massive
than the accreting object. When the orbital period is smaller than ~6 hours,
this mechanism does not work and the CBSS with such periods are believed to be
fed by a distinct mechanism: the wind-driven accretion. Such a mechanism has
been proposed to explain the properties of objects like SMC 13, T Pyx and V617
Sgr. One observational property that offers a critical test for discriminating
between the above two possibilities is the orbital period change. As systems
with wind-driven accretion evolve with increasing periods, some of them may
reach quite long orbital periods. The above critical test may, therefore, also
be applied to orbital periods longer than 6 hours. CAL 87 is an eclipsing
system in the LMC with an orbital period of 10.6 hours that could provide the
opportunity for testing the hypothesis of the system being powered by
wind-driven accretion. We obtained eclipse timings for this system and show
that its orbital period increases with a rate of P/Pdot = +7.2(+/-1.3) X 10^{6}
years. Contrary to the common belief, we conclude that CAL 87 is the first
confirmed case of a wind-driven CBSS with an orbital period longer than 6
hours. The system is probably an evolved object that had an initial secondary
mass of M2i=0.63 solar masses but is currently reduced to about M2=0.34 solar
masses. We discuss evidence that other CBSS, like CAL 83 and V Sge stars, like
WX Cen, are probably also wind-driven systems. This may in fact be the rule,
and systems with inverted mass ratio, the exception.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:48:40 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Oliveira",
"A. S.",
""
],
[
"Steiner",
"J. E.",
""
]
] |
0707.3442 | Peter Waddell | Peter J. Waddell and Prasanth Kalakota | Combined Sum of Squares Penalties for Molecular Divergence Time
Estimation | 18 pages, 3 figures, 2 tables | null | null | null | q-bio.PE q-bio.GN q-bio.QM | null | Estimates of molecular divergence times when rates of evolution vary require
the assumption of a model of rate change. Brownian motion is one such model,
and since rates cannot become negative, a log Brownian model seems appropriate.
Divergence time estimates can then be made using weighted least squares
penalties. As sequences become long, this approach effectively becomes
equivalent to penalized likelihood or Bayesian approaches. Different forms of
the least squares penalty are considered to take into account correlation due
to shared ancestors. It is shown that a scale parameter is also needed since
the sum of squares changes with the scale of time. Errors or uncertainty on
fossil calibrations, may be folded in with errors due to the stochastic nature
of Brownian motion and ancestral polymorphism, giving a total sum of squares to
be minimized. Applying these methods to placental mammal data the estimated age
of the root decreases from 125 to about 94 mybp. However, multiple fossil
calibration points and relative molecular divergence times inflate the sum of
squares more than expected. If fossil data are also bootstrapped, then the
confidence interval for the root of placental mammals varies widely from ~70 to
130 mybp. Such a wide interval suggests that more and better fossil calibration
data is needed and/or better models of rate evolution are needed and/or better
molecular data are needed. Until these issues are thoroughly investigated, it
is premature to declare either the old molecular dates frequently obtained
(e.g. > 110 mybp) or the lack of identified placental fossils in the
Cretaceous, more indicative of when crown-group placental mammals evolved.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 19:59:59 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Jul 2007 21:11:17 GMT"
}
] | 2007-07-24T00:00:00 | [
[
"Waddell",
"Peter J.",
""
],
[
"Kalakota",
"Prasanth",
""
]
] |
0707.3443 | James Wray | James J. Wray (1) and James E. Gunn (2) ((1) Cornell University, (2)
Princeton University) | A New Technique for Galaxy Photometric Redshifts in the Sloan Digital
Sky Survey | 24 pages, 10 figures, accepted to ApJ; added tables and references | Astrophys.J.678:144-153,2008 | 10.1086/529127 | null | astro-ph | null | Traditional photometric redshift methods use only color information about the
objects in question to estimate their redshifts. This paper introduces a new
method utilizing colors, luminosity, surface brightness, and radial light
profile to measure the redshifts of galaxies in the Sloan Digital Sky Survey
(SDSS). We take a statistical approach: distributions of galaxies from the SDSS
Large-Scale Structure (LSS; spectroscopic) sample are constructed at a range of
redshifts, and target galaxies are compared to these distributions. An adaptive
mesh is implemented to increase the percentage of the parameter space populated
by the LSS galaxies. We test the method on a subset of galaxies from the LSS
sample, yielding rms Delta-z of 0.025 for red galaxies and 0.030 for blue
galaxies (all with z < 0.25). Possible future improvements to this promising
technique are described, as is our ongoing work to extend the method to
galaxies at higher redshift.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:00:18 GMT"
},
{
"version": "v2",
"created": "Thu, 10 Jan 2008 00:21:55 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Wray",
"James J.",
""
],
[
"Gunn",
"James E.",
""
]
] |
0707.3444 | Michael Salem | Lawrence J. Hall, Michael P. Salem and Taizan Watari | Quark and Lepton Masses from Gaussian Landscapes | 5 pages, 1 figure; v2: clarifications added; v3: slightly extended
from version to appear in PRL | Phys.Rev.Lett.100:141801,2008 | 10.1103/PhysRevLett.100.141801 | UCB-PTH-07/11, LBNL-62797, CALT-68-2653, UT-07-18 | hep-ph hep-th | null | The flavor structure of the Standard Model might arise from random selection
on a landscape. We propose a class of simple models, ``Gaussian landscapes,''
where Yukawa couplings derive from overlap integrals of Gaussian wavefunctions
on extra-dimensions. Statistics of vacua are generated by scanning the peak
positions of these zero-modes, giving probability distributions for all flavor
observables. Gaussian landscapes can broadly account for all observed flavor
patterns with very few free parameters. For example, the generation structure
in the quark sector follows from the overlap integrals for both the up and down
type Yukawas sharing the localized wavefunctions of the quark doublets and the
Higgs boson. Although Gaussian landscapes predict broad probability
distributions, the flavor observables are correlated and we show that
accounting for measured flavor parameters creates sharper distributions for
future neutrino measurements.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 16:43:18 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Aug 2007 21:45:58 GMT"
},
{
"version": "v3",
"created": "Fri, 11 Apr 2008 13:24:11 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hall",
"Lawrence J.",
""
],
[
"Salem",
"Michael P.",
""
],
[
"Watari",
"Taizan",
""
]
] |
0707.3445 | Jeremy Tinker | Jeremy L. Tinker, Charlie Conroy, Peder Norberg, Santiago G. Patiri,
David H. Weinberg, Michael S. Warren | Void Statistics in Large Galaxy Redshift Surveys: Does Halo Occupation
of Field Galaxies Depend on Environment? | 20 emulateapj pages, 9 figures. submitted to ApJ | null | 10.1086/589983 | null | astro-ph | null | We use measurements of the projected galaxy correlation function w_p and
galaxy void statistics to test whether the galaxy content of halos of fixed
mass is systematically different in low density environments. We present new
measurements of the void probability function (VPF) and underdensity
probability function (UPF) from Data Release Four of the Sloan Digital Sky
Survey, as well as new measurements of the VPF from the full data release of
the Two-Degree Field Galaxy Redshift Survey. We compare these measurements to
predictions calculated from models of the Halo Occupation Distribution (HOD)
that are constrained to match both w_p and the space density of galaxies. The
standard implementation of the HOD assumes that galaxy occupation depends on
halo mass only, and is independent of local environment. For luminosity-defined
samples, we find that the standard HOD prediction is a good match to the
observations, and the data exclude models in which galaxy formation efficiency
is reduced in low-density environments. More remarkably, we find that the void
statistics of red and blue galaxies (at L ~ 0.4L_*) are perfectly predicted by
standard HOD models matched to the correlation function of these samples,
ruling out "assembly bias" models in which galaxy color is correlated with
large-scale environment at fixed halo mass. We conclude that the luminosity and
color of field galaxies are determined predominantly by the mass of the halo in
which they reside and have little direct dependence on the environment in which
the host halo formed. In broader terms, our results show that the sizes and
emptiness of voids found in the distribution of L > 0.2L_* galaxies are in
excellent agreement with the predictions of a standard cosmological model with
a simple connection between galaxies and dark matter halos. (abridged)
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:55:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tinker",
"Jeremy L.",
""
],
[
"Conroy",
"Charlie",
""
],
[
"Norberg",
"Peder",
""
],
[
"Patiri",
"Santiago G.",
""
],
[
"Weinberg",
"David H.",
""
],
[
"Warren",
"Michael S.",
""
]
] |
0707.3446 | Michael Salem | Lawrence J. Hall, Michael P. Salem and Taizan Watari | Statistical Understanding of Quark and Lepton Masses in Gaussian
Landscapes | 86 pages, 26 figures, 2 tables, and table of contents | Phys.Rev.D76:093001,2007 | 10.1103/PhysRevD.76.093001 | UCB-PTH-07/12, LBNL-62798, CALT-68-2654, UT-07-19 | hep-ph hep-th | null | The fundamental theory of nature may allow a large landscape of vacua. Even
if the theory contains a unified gauge symmetry, the 22 flavor parameters of
the Standard Model, including neutrino masses, may be largely determined by the
statistics of this landscape, and not by any symmetry. Then the measured values
of the flavor parameters do not lead to any fundamental symmetries, but are
statistical accidents; their precise values do not provide any insights into
the fundamental theory, rather the overall pattern of flavor reflects the
underlying landscape. We investigate whether random selection from the
statistics of a simple landscape can explain the broad patterns of quark,
charged lepton, and neutrino masses and mixings. We propose Gaussian landscapes
as simplified models of landscapes where Yukawa couplings result from overlap
integrals of zero-mode wavefunctions in higher-dimensional supersymmetric gauge
theories. In terms of just five free parameters, such landscapes can account
for all gross features of flavor, including: the hierarchy of quark and charged
lepton masses; small quark mixing angles, with 13 mixing less than 12 and 23
mixing; very light Majorana neutrino masses, with the solar to atmospheric
neutrino mass ratio consistent with data; distributions for leptonic 12 and 23
mixings that are peaked at large values, while the distribution for 13 mixing
is peaked at low values; and order unity CP violating phases in both the quark
and lepton sectors. While the statistical distributions for flavor parameters
are broad, the distributions are robust to changes in the geometry of the extra
dimensions. Constraining the distributions by loose cuts about observed values
leads to narrower distributions for neutrino measurements of 13 mixing, CP
violation, and neutrinoless double beta decay.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 16:25:50 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 12:16:38 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Hall",
"Lawrence J.",
""
],
[
"Salem",
"Michael P.",
""
],
[
"Watari",
"Taizan",
""
]
] |
0707.3447 | Fr\'ed\'eric Ronga | O. Buchmueller, R. Cavanaugh, A. De Roeck, S. Heinemeyer, G. Isidori,
P. Paradisi, F.J. Ronga, A.M. Weber, G. Weiglein | Prediction for the Lightest Higgs Boson Mass in the CMSSM using Indirect
Experimental Constraints | Published version (formatting corrected): 12 pages, 7 figures,
requires espcrc2.sty | Phys.Lett.B657:87-94,2007 | 10.1016/j.physletb.2007.09.058 | IPPP/07/43, DCPT/07/86, MPP-2007-142 | hep-ph | null | Measurements at low energies provide interesting indirect information about
masses of particles that are (so far) too heavy to be produced directly.
Motivated by recent progress in consistently and rigorously calculating
electroweak precision observables and flavour related observables, we derive
the preferred value for m_h in the Constrained Minimal Supersymmetric Standard
Model (CMSSM), obtained from a fit taking into account electroweak precision
data, flavour physics observables and the abundance of Cold Dark Matter. No
restriction is imposed on m_h itself: the experimental bound from direct Higgs
boson search at LEP is not included in the fit. A multi-parameter chi^2 is
minimized with respect to the free parameters of the CMSSM, M_0, M_1/2, A_0,
tan(beta). A statistical comparison with the Standard Model fit to the
electroweak precision data is made. The preferred value for the lightest Higgs
boson mass in the CMSSM is found to be m_h^CMSSM = 110+8-10(exp.)+-3(theo.)
GeV/c^2, where the first uncertainty is experimental and the second uncertainty
is theoretical. This value is in agreement with the limit from direct Higgs
boson search at LEP.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:19:53 GMT"
},
{
"version": "v2",
"created": "Mon, 26 Nov 2007 09:59:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Buchmueller",
"O.",
""
],
[
"Cavanaugh",
"R.",
""
],
[
"De Roeck",
"A.",
""
],
[
"Heinemeyer",
"S.",
""
],
[
"Isidori",
"G.",
""
],
[
"Paradisi",
"P.",
""
],
[
"Ronga",
"F. J.",
""
],
[
"Weber",
"A. M.",
""
],
[
"Weiglein",
"G.",
""
]
] |
0707.3448 | Ivan Nourdin | Ivan Nourdin (PMA), David Nualart | Central limit theorems for multiple Skorohod integrals | 32 pages; major changes in Sections 4 and 5 | null | null | null | math.PR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we prove a central limit theorem for a sequence of iterated
Shorohod integrals using the techniques of Malliavin calculus. The convergence
is stable, and the limit is a conditionally Gaussian random variable. Some
applications to sequences of multiple stochastic integrals, and renormalized
weighted Hermite variations of the fractional Brownian motion are discussed.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:40:15 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Sep 2007 11:41:47 GMT"
},
{
"version": "v3",
"created": "Thu, 10 Jan 2008 08:09:04 GMT"
},
{
"version": "v4",
"created": "Thu, 21 Aug 2008 05:02:30 GMT"
},
{
"version": "v5",
"created": "Thu, 3 Sep 2009 06:45:53 GMT"
}
] | 2009-09-03T00:00:00 | [
[
"Nourdin",
"Ivan",
"",
"PMA"
],
[
"Nualart",
"David",
""
]
] |
0707.3449 | Jean Mairesse | Thu-Ha Dao-Thi (LIAFA), Jean Mairesse (LIAFA) | Zero-automatic queues and product form | null | Advances in Applied Probability 39, 2 (2007) 429-461 | null | null | cs.DM | null | We introduce and study a new model: 0-automatic queues. Roughly, 0-automatic
queues are characterized by a special buffering mechanism evolving like a
random walk on some infinite group or monoid. The salient result is that all
stable 0-automatic queues have a product form stationary distribution and a
Poisson output process. When considering the two simplest and extremal cases of
0-automatic queues, we recover the simple M/M/1 queue, and Gelenbe's G-queue
with positive and negative customers.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:41:43 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Dao-Thi",
"Thu-Ha",
"",
"LIAFA"
],
[
"Mairesse",
"Jean",
"",
"LIAFA"
]
] |
0707.3450 | Paschalis Karageorgis | Paschalis Karageorgis | Stability and intersection properties of solutions to the nonlinear
biharmonic equation | null | null | null | null | math.AP | null | We study the positive, regular, radially symmetric solutions to the nonlinear
biharmonic equation $\Delta^2 \phi = \phi^p$. First, we show that there exists
a critical value $p_c$, depending on the space dimension, such that the
solutions are linearly unstable if $p<p_c$ and linearly stable if $p\geq p_c$.
Then, we focus on the supercritical case $p\geq p_c$ and we show that the
graphs of no two solutions intersect one another.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:43:23 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Karageorgis",
"Paschalis",
""
]
] |
0707.3451 | Gerald Teschl | Helge Krueger and Gerald Teschl | Relative Oscillation Theory for Sturm-Liouville Operators Extended | 16 pages | J. Funct. Anal. 254-6, 1702-1720 (2008) | 10.1016/j.jfa.2007.10.007 | null | math.SP math-ph math.MP | null | We extend relative oscillation theory to the case of Sturm--Liouville
operators $H u = r^{-1}(-(pu')'+q u)$ with different $p$'s. We show that the
weighted number of zeros of Wronskians of certain solutions equals the value of
Krein's spectral shift function inside essential spectral gaps.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:15:03 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Oct 2007 20:34:13 GMT"
}
] | 2008-02-22T00:00:00 | [
[
"Krueger",
"Helge",
""
],
[
"Teschl",
"Gerald",
""
]
] |
0707.3452 | Sherri Honza | Jorge Carmona-Reyes, Jimmy Schmoke, Mike Cook, Jie Kong and Truell
Hyde | Vertical Dust Particle Chains-Mass and Charge Measurements | null | null | null | CASPER-07-04 | astro-ph | null | Dusty plasmas have generated a large amount of interest since the discovery
of ordered structure (crystal) formation in experimentally generated complex
plasmas in 1994. Dust particles within the plasma sheath generated in these
complex plasmas can form vertical chains due to the streaming ion wakefield.
For the simplest of these configurations (a two particle chain), the particle
closest to the lower electrode will generally remain in the shadow of the
particle farthest from the lower electrode. These results in the two particles
feeling differing ion drag forces: the top particle is acted on by the ion drag
force directed from the plasma to the lower electrode, while the bottom
particle is acted upon by the resulting wakefield produced by the interaction
of the upper particle with the ion drag force. This dynamic situation currently
provides the best known experimental environment for examining the physics
behind the ion drag force and its interaction with the plasma sheath. An
experimental method for investigating the interaction between pair-particle
chains based on modulating the bias on the lower electrode employing a DC bias
modulation technique will be presented.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 20:47:57 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Carmona-Reyes",
"Jorge",
""
],
[
"Schmoke",
"Jimmy",
""
],
[
"Cook",
"Mike",
""
],
[
"Kong",
"Jie",
""
],
[
"Hyde",
"Truell",
""
]
] |
0707.3453 | Aleksandr Zheltukhin | A. A. Zheltukhin | Unification of twistors and Ramond vectors | Comments: 11 pages, v2 published in Phys. Lett.: misprints corrected
and clarifications added | Phys.Lett.B658:82-89,2007 | 10.1016/j.physletb.2007.10.037 | null | hep-th | null | We generalize the idea of supertwistors and introduce a new supersymmetric
object - the $\theta$-twistor which includes the composite Ramond vector [11]
well known from the spinning string dynamics. The symmetries of the chiral
$\theta$-twistor superspace are studied. It is shown that the chiral spin
structure introduced by the $\theta$-twistor breaks the superconformal boost
symmetry but preserves the scale symmetry and the super-Poincare symmetry. This
geometrical effect of breaking correlates with the Gross-Wess effect of the
conformal boost breaking for bosonic scattering amplitudes.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:08:43 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Dec 2007 22:03:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zheltukhin",
"A. A.",
""
]
] |
0707.3454 | Andras Pal Mr. | Andras Pal and Aron Suli | Solving Linearized Equations of the $N$-body Problem Using the
Lie-integration Method | accepted for publication in MNRAS (13 pages, 4 figures); see
http://cm.elte.hu/lie (cm.elte.hu/lie) for software | null | 10.1111/j.1365-2966.2007.12248.x | MN-07-0767-MJ | astro-ph | null | Several integration schemes exits to solve the equations of motion of the
$N$-body problem. The Lie-integration method is based on the idea to solve
ordinary differential equations with Lie-series. In the 1980s this method was
applied for the $N$-body problem by giving the recurrence formula for the
calculation of the Lie-terms. The aim of this works is to present the
recurrence formulae for the linearized equations of motion of $N$-body systems.
We prove a lemma which greatly simplifies the derivation of the recurrence
formulae for the linearized equations if the recurrence formulae for the
equations of motions are known. The Lie-integrator is compared with other
well-known methods. The optimal step size and order of the Lie-integrator are
calculated. It is shown that a fine-tuned Lie-integrator can be 30%-40% faster
than other integration methods.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:14:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Pal",
"Andras",
""
],
[
"Suli",
"Aron",
""
]
] |
0707.3455 | Ross Mair | L. L. Tsai, R. W. Mair, C.-H. Li, M. S. Rosen, S. Patz and R. L.
Walsworth | Posture-Dependent Human 3He Lung Imaging in an Open Access MRI System:
Initial Results | single pdf file in manuscript format, 35 pages, 5 figures Submitted
to Academic Radiology | null | null | null | physics.med-ph | null | The human lung and its functions are extremely sensitive to orientation and
posture, and debate continues as to the role of gravity and the surrounding
anatomy in determining lung function and heterogeneity of perfusion and
ventilation. However, study of these effects is difficult. The conventional
high-field magnets used for most hyperpolarized 3He MRI of the human lung, and
most other common radiological imaging modalities including PET and CT,
restrict subjects to lying horizontally, minimizing most gravitational effects.
In this paper, we briefly review the motivation for posture-dependent studies
of human lung function, and present initial imaging results of human lungs in
the supine and vertical body orientations using inhaled hyperpolarized 3He gas
and an open-access MRI instrument. The open geometry of this MRI system
features a "walk-in" capability that permits subjects to be imaged in vertical
and horizontal positions, and potentially allows for complete rotation of the
orientation of the imaging subject in a two-dimensional plane. Initial results
include two-dimensional lung images acquired with ~ 4 mm in-plane resolution
and three-dimensional images with ~ 1.5 cm slice thickness. Effects of posture
variation are observed.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:18:01 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Tsai",
"L. L.",
""
],
[
"Mair",
"R. W.",
""
],
[
"Li",
"C. -H.",
""
],
[
"Rosen",
"M. S.",
""
],
[
"Patz",
"S.",
""
],
[
"Walsworth",
"R. L.",
""
]
] |
0707.3456 | Paul J. Wiita | Paul J. Wiita, Gopal-Krishna, Samir Dhurde, Pronoy Sircar | Effects of Jet Opening Angle and Velocity Structure on Blazar Parameters | 5 pages, 1 figure, to appear in Extragalactic Jets: Theory and
Observation from Radio to Gamma Ray, T.A. Rector and D.S. De Young, eds | null | null | null | astro-ph | null | We had earlier shown that for a constant velocity jet the discrepancy between
the low speeds indicated by VLBI knot motions and the high Doppler factors
inferred from emission of TeV photons could be reconciled if ultrarelativistic
jets possessed modest opening angles. Here we evaluate the (flux-weighted)
viewing angles of the jet and the apparent speeds and Doppler factors of the
radio knots on parsec scales. The influence of the jet opening angle on these
radio knot parameters are found for the usually considered types of
relativistic nuclear jets: those with uniform bulk speeds and those where the
bulk Lorentz factor of the flow decreases with distance from the jet axis,
known as `spine--sheath' flows. For both types of jet velocity structures the
expectation value of the jet orientation angle at first falls dramatically with
increases in the (central) jet Lorentz factor, but for extremely relativistic
jets it levels off at a fraction of the opening angle. The effective values of
the apparent speeds and Doppler factors of the knots always decline
substantially with increasing jet opening angle. The rarity of highly
superluminal parsec-scale radio components in TeV blazars can be understood if
their jets are both highly relativistic and intrinsically weaker, so probably
less well collimated, than the jets in ordinary blazars.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:42:37 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Wiita",
"Paul J.",
""
],
[
"Gopal-Krishna",
"",
""
],
[
"Dhurde",
"Samir",
""
],
[
"Sircar",
"Pronoy",
""
]
] |
0707.3457 | Chenguang Lu | Chenguang Lu | A Generalized Information Formula as the Bridge between Shannon and
Popper | 8 pages, 5 figures | null | null | null | cs.IT cs.AI math.IT | null | A generalized information formula related to logical probability and fuzzy
set is deduced from the classical information formula. The new information
measure accords with to Popper's criterion for knowledge evolution very much.
In comparison with square error criterion, the information criterion does not
only reflect error of a proposition, but also reflects the particularity of the
event described by the proposition. It gives a proposition with less logical
probability higher evaluation. The paper introduces how to select a prediction
or sentence from many for forecasts and language translations according to the
generalized information criterion. It also introduces the rate fidelity theory,
which comes from the improvement of the rate distortion theory in the classical
information theory by replacing distortion (i.e. average error) criterion with
the generalized mutual information criterion, for data compression and
communication efficiency. Some interesting conclusions are obtained from the
rate-fidelity function in relation to image communication. It also discusses
how to improve Popper's theory.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 00:04:32 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Lu",
"Chenguang",
""
]
] |
0707.3458 | Shaul Mukamel | Shaul Mukamel | Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the
Damping-Sign Controversy | null | null | 10.1103/PhysRevA.76.021803 | null | quant-ph | null | Frequency-domain nonlinear wave mixing processes may be described either
using response functions whereby the signal is generated after all interactions
with the incoming fields, or in terms of scattering amplitudes where all fields
are treated symetrically with no specific time ordering. Closed Green's
function expressions derived for the two types of signals have different
analytical properties. The recent controversy regarding the sign of radiative
damping in the linear (Kramers Heisenberg) formula is put in a broader context.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:45:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mukamel",
"Shaul",
""
]
] |
0707.3459 | Joerg Schmalian | K. M. Ho, J. Schmalian and C. Z. Wang | Gutzwiller density functional theory for correlated electron systems | 4 pages | null | 10.1103/PhysRevB.77.073101 | null | cond-mat.supr-con cond-mat.mtrl-sci | null | We develop a new density functional theory (DFT) and formalism for correlated
electron systems by taking as reference an interacting electron system that has
a ground state wavefunction which obeys exactly the Gutzwiller approximation
for all one particle operators. The solution of the many electron problem is
mapped onto the self-consistent solution of a set of single particle
Schroedinger equations analogous to standard DFT-LDA calculations.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 21:45:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ho",
"K. M.",
""
],
[
"Schmalian",
"J.",
""
],
[
"Wang",
"C. Z.",
""
]
] |
0707.3460 | Ken D. Olum | Jose J. Blanco-Pillado and Ken D. Olum | Monopole annihilation in cosmic necklaces | 17 pages, 4 figures. Major revision discussing many additional
scenarios. | JCAP 1005:014,2010 | 10.1088/1475-7516/2010/05/014 | null | astro-ph gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A sequence of two symmetry breaking transitions in the early universe may
produce monopoles whose flux is confined into two strings each, which thus
assemble into "necklaces" with monopoles as beads. Such "cosmic necklaces" have
been proposed as a source of ultra-high-energy cosmic rays. We analyze the
evolution of these systems and show that essentially all monopoles annihilate
or leave the string at early times, after which cosmic necklaces evolve in a
similar way to a network of ordinary cosmic strings. We investigate several
modifications to the basic picture, but in nearly all cases we find that too
few monopoles remain on the necklaces to produce any observable cosmic rays.
There may be a small window for superconducting condensates to prevent
annihilations, but only if both the string and the condensate scale are very
high.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 22:04:41 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Aug 2007 22:48:52 GMT"
},
{
"version": "v3",
"created": "Sat, 6 Mar 2010 00:53:33 GMT"
}
] | 2010-05-25T00:00:00 | [
[
"Blanco-Pillado",
"Jose J.",
""
],
[
"Olum",
"Ken D.",
""
]
] |
0707.3461 | Dinesh Krithivasan | D. Krithivasan and S. S. Pradhan | Lattices for Distributed Source Coding: Jointly Gaussian Sources and
Reconstruction of a Linear Function | 33 pages, 7 figures | null | null | null | cs.IT math.IT | null | Consider a pair of correlated Gaussian sources (X1,X2). Two separate encoders
observe the two components and communicate compressed versions of their
observations to a common decoder. The decoder is interested in reconstructing a
linear combination of X1 and X2 to within a mean-square distortion of D. We
obtain an inner bound to the optimal rate-distortion region for this problem. A
portion of this inner bound is achieved by a scheme that reconstructs the
linear function directly rather than reconstructing the individual components
X1 and X2 first. This results in a better rate region for certain parameter
values. Our coding scheme relies on lattice coding techniques in contrast to
more prevalent random coding arguments used to demonstrate achievable rate
regions in information theory. We then consider the case of linear
reconstruction of K sources and provide an inner bound to the optimal
rate-distortion region. Some parts of the inner bound are achieved using the
following coding structure: lattice vector quantization followed by
"correlated" lattice-structured binning.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 22:55:43 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Krithivasan",
"D.",
""
],
[
"Pradhan",
"S. S.",
""
]
] |
0707.3462 | Noah Stein | Noah D. Stein, Asuman Ozdaglar, Pablo A. Parrilo | Separable and Low-Rank Continuous Games | null | International Journal of Game Theory, Vol. 37, No. 4, pp. 457-474,
2008. | 10.1007/s00182-008-0129-2 | null | cs.GT math.OC | null | In this paper, we study nonzero-sum separable games, which are continuous
games whose payoffs take a sum-of-products form. Included in this subclass are
all finite games and polynomial games. We investigate the structure of
equilibria in separable games. We show that these games admit finitely
supported Nash equilibria. Motivated by the bounds on the supports of mixed
equilibria in two-player finite games in terms of the ranks of the payoff
matrices, we define the notion of the rank of an n-player continuous game and
use this to provide bounds on the cardinality of the support of equilibrium
strategies. We present a general characterization theorem that states that a
continuous game has finite rank if and only if it is separable. Using our rank
results, we present an efficient algorithm for computing approximate equilibria
of two-player separable games with fixed strategy spaces in time polynomial in
the rank of the game.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 16:20:59 GMT"
}
] | 2010-04-26T00:00:00 | [
[
"Stein",
"Noah D.",
""
],
[
"Ozdaglar",
"Asuman",
""
],
[
"Parrilo",
"Pablo A.",
""
]
] |
0707.3463 | Peter Silvestrov | P. G. Silvestrov and K. B. Efetov | Charge accumulation at the boundaries of a graphene strip induced by a
gate voltage: Electrostatic approach | 5 pages, 6 figures, Title changed due to Editor | Phys. Rev. B 77, 155436 (2008) | 10.1103/PhysRevB.77.155436 | null | cond-mat.mes-hall | null | Distribution of charge induced by a gate voltage in a graphene strip is
investigated. We calculate analytically the charge profile and demonstrate a
strong(macroscopic) charge accumulation along the boundaries of a
micrometers-wide strip. This charge inhomogeneity is especially important in
the quantum Hall regime where we predict the doubling of the number of edge
states and coexistence of two different types of such states. Applications to
graphene-based nanoelectronics are discussed.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 22:43:57 GMT"
},
{
"version": "v2",
"created": "Sun, 14 Oct 2007 18:08:44 GMT"
},
{
"version": "v3",
"created": "Tue, 3 Jun 2008 22:17:47 GMT"
}
] | 2008-06-04T00:00:00 | [
[
"Silvestrov",
"P. G.",
""
],
[
"Efetov",
"K. B.",
""
]
] |
0707.3464 | Emmanuel Tannenbaum | Emmanuel Tannenbaum | A comparison of three replication strategies in complex multicellular
organisms: Asexual replication, sexual replication with identical gametes,
and sexual replication with distinct sperm and egg gametes | 18 pages, figures included with journal submission | null | 10.1103/PhysRevE.77.011915 | null | q-bio.PE | null | This paper studies the mutation-selection balance in three simplified
replication models. The first model considers a population of organisms
replicating via the production of asexual spores. The second model considers a
sexually replicating population that produces identical gametes. The third
model considers a sexually replicating population that produces distinct sperm
and egg gametes. All models assume diploid organisms whose genomes consist of
two chromosomes, each of which is taken to be functional if equal to some
master sequence, and defective otherwise. In the asexual population, the
asexual diploid spores develop directly into adult organisms. In the sexual
populations, the haploid gametes enter a haploid pool, where they may fuse with
other haploids. The resulting immature diploid organisms then proceed to
develop into mature organisms. Based on an analysis of all three models, we
find that, as organism size increases, a sexually replicating population can
only outcompete an asexually replicating population if the adult organisms
produce distinct sperm and egg gametes. A sexual replication strategy that is
based on the production of large numbers of sperm cells to fertilize a small
number of eggs is found to be necessary in order to maintain a sufficiently low
cost for sex for the strategy to be selected for over a purely asexual
strategy. We discuss the usefulness of this model in understanding the
evolution and maintenance of sexual replication as the preferred replication
strategy in complex, multicellular organisms.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:12:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tannenbaum",
"Emmanuel",
""
]
] |
0707.3465 | Claus O. Wilke | Eric Brunet, Igor M. Rouzine, Claus O. Wilke | The stochastic edge in adaptive evolution | 36 pages, 4 figures | null | null | null | q-bio.PE | null | In a recent article, Desai and Fisher (2007) proposed that the speed of
adaptation in an asexual population is determined by the dynamics of the
stochastic edge of the population, that is, by the emergence and subsequent
establishment of rare mutants that exceed the fitness of all sequences
currently present in the population. Desai and Fisher perform an elaborate
stochastic calculation of the mean time $\tau$ until a new class of mutants has
been established, and interpret $1/\tau$ as the speed of adaptation. As they
note, however, their calculations are valid only for moderate speeds. This
limitation arises from their method to determine $\tau$: Desai and Fisher
back-extrapolate the value of $\tau$ from the best-fit class' exponential
growth at infinite time. This approach is not valid when the population adapts
rapidly, because in this case the best-fit class grows non-exponentially during
the relevant time interval. Here, we substantially extend Desai and Fisher's
analysis of the stochastic edge. We show that we can apply Desai and Fisher's
method to high speeds by either exponentially back-extrapolating from finite
time or using a non-exponential back-extrapolation. Our results are compatible
with predictions made using a different analytical approach (Rouzine et al.
2003, 2007), and agree well with numerical simulations.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:31:29 GMT"
},
{
"version": "v2",
"created": "Tue, 18 Dec 2007 23:22:06 GMT"
}
] | 2007-12-19T00:00:00 | [
[
"Brunet",
"Eric",
""
],
[
"Rouzine",
"Igor M.",
""
],
[
"Wilke",
"Claus O.",
""
]
] |
0707.3466 | Eckehard Mielke W. | Eckehard W. Mielke | Einsteinian gravity from a topological action | 14 pages | Phys.Rev.D77:084020,2008; Erratum-ibid.D77:109902,2008 | 10.1103/PhysRevD.77.084020 10.1103/PhysRevD.77.109902 | null | hep-th | null | The curvature-squared model of gravity, in the affine form proposed by Weyl
and Yang, is deduced from a topological action in 4D. More specifically, we
start from the Pontrjagin (or Euler) invariant. Using the BRST antifield
formalism with a double duality gauge fixing, we obtain a consistent
quantization in spaces of double dual curvature as classical instanton type
background.
However, exact vacuum solutions with double duality properties exhibit a
`vacuum degeneracy'. By modifying the duality via a scale breaking term, we
demonstrate that only Einstein's equations with an induced cosmological
constant emerge for the topology of the macroscopic background. This may have
repercussions on the problem of `dark energy' as well as `dark matter' modeled
by a torsion induced quintaxion.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:38:21 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Sep 2007 22:30:51 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Mielke",
"Eckehard W.",
""
]
] |
0707.3467 | Rozanova Olga | Olga Rozanova | Generalized momenta of mass and their applications to the flow of
compressible fluid | 10 pages, Proceedings of the International Conference on Hyperbolic
Problems, Lyon, 2006, France. In press | Hyperbolic Problems: Theory, Numerics, Applications, Springer
Berlin Heidelberg, 2008, vol. IV, pp. 919-927 | 10.1007/978-3-540-75712-2_96 | null | math.AP math-ph math.MP | null | We present a technique that allows to obtain certain results in the
compressible fluid theory: in particular, it is a nonexistence result for the
highly decreasing at infinity solutions to the Navier-Stokes equations, the
construction of the solutions with uniform deformation and the study of
behavior of the boundary of a material volume of liquid.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:39:25 GMT"
}
] | 2008-01-19T00:00:00 | [
[
"Rozanova",
"Olga",
""
]
] |
0707.3468 | Abdul Salam Jarrah | Eduardo Sontag, Alan Veliz-Cuba, Reinhard Laubenbacher, Abdul Salam
Jarrah | The effect of negative feedback loops on the dynamics of Boolean
networks | null | null | 10.1529/biophysj.107.125021 | null | q-bio.QM q-bio.MN | null | Feedback loops in a dynamic network play an important role in determining the
dynamics of that network. Through a computational study, in this paper we show
that networks with fewer independent negative feedback loops tend to exhibit
more regular behavior than those with more negative loops. To be precise, we
study the relationship between the number of independent feedback loops and the
number and length of the limit cycles in the phase space of dynamic Boolean
networks. We show that, as the number of independent negative feedback loops
increases, the number (length) of limit cycles tends to decrease (increase).
These conclusions are consistent with the fact, for certain natural biological
networks, that they on the one hand exhibit generally regular behavior and on
the other hand show less negative feedback loops than randomized networks with
the same numbers of nodes and connectivity.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:46:58 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Nov 2007 17:45:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sontag",
"Eduardo",
""
],
[
"Veliz-Cuba",
"Alan",
""
],
[
"Laubenbacher",
"Reinhard",
""
],
[
"Jarrah",
"Abdul Salam",
""
]
] |
0707.3469 | Claus O. Wilke | Igor M. Rouzine, Eric Brunet, Claus O. Wilke | The traveling wave approach to asexual evolution: Muller's ratchet and
speed of adaptation | 50 pages, 8 figures | null | 10.1016/j.tpb.2007.10.004 | null | q-bio.PE | null | We use traveling-wave theory to derive expressions for the rate of
accumulation of deleterious mutations under Muller's ratchet and the speed of
adaptation under positive selection in asexual populations. Traveling-wave
theory is a semi-deterministic description of an evolving population, where the
bulk of the population is modeled using deterministic equations, but the class
of the highest-fitness genotypes, whose evolution over time determines loss or
gain of fitness in the population, is given proper stochastic treatment. We
derive improved methods to model the highest-fitness class (the stochastic
edge) for both Muller's ratchet and adaptive evolution, and calculate analytic
correction terms that compensate for inaccuracies which arise when treating
discrete fitness classes as a continuum. We show that traveling wave theory
makes excellent predictions for the rate of mutation accumulation in the case
of Muller's ratchet, and makes good predictions for the speed of adaptation in
a very broad parameter range. We predict the adaptation rate to grow
logarithmically in the population size until the population size is extremely
large.
| [
{
"version": "v1",
"created": "Mon, 23 Jul 2007 23:47:54 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Oct 2007 14:40:16 GMT"
}
] | 2007-12-19T00:00:00 | [
[
"Rouzine",
"Igor M.",
""
],
[
"Brunet",
"Eric",
""
],
[
"Wilke",
"Claus O.",
""
]
] |
0707.3470 | Fuquan Fang | Fuquan Fang, Yuguang Zhang | Convergence of Kaehler-Ricci flow with integral curvature bound | null | null | null | null | math.DG math.GT | null | Let $g(t)$, $t\in [0, +\infty)$, be a solution of the normalized
K\"ahler-Ricci flow on a compact K\"ahler $n$-manifold $M$ with $c_{1}(M)>0$
and initial metric $g (0)\in 2\pi c_{1}(M)$.
If there is a constant $C$ independent of $t$ such that $$
\int_{M}|Rm(g(t))|^{n}dv_{t}\leq C,$$ then, for any $t_{k}\to \infty$, a
subsequence of $(M, g(t_{k}))$ converges to a compact orbifold $(X, h)$ with
only finite many singular points $\{q_{j}\}$ in the Gromov-Hausdorff sense,
where $h$ is a K\"ahler metric on $X\backslash \{q_{j}\}$ satisfying the
K\"ahler-Ricci soliton equation, i.e. there is a smooth function $f$ such that
$$Ric(h)-h=\nabla\bar{\nabla}f, {\rm and}\it \nabla \nabla f=\bar{\nabla}
\bar{\nabla} f=0. $$
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 00:04:07 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Fang",
"Fuquan",
""
],
[
"Zhang",
"Yuguang",
""
]
] |
0707.3471 | Qing-Guo Huang | Qing-Guo Huang, Miao Li and Yi Wang | Eternal Chaotic Inflation is Prohibited by Weak Gravity Conjecture | 10 pages | JCAP0709:013,2007 | 10.1088/1475-7516/2007/09/013 | null | hep-th astro-ph gr-qc hep-ph | null | We investigate whether the eternal chaotic inflation can be achieved when the
weak gravity conjecture is taken into account. We show that even the assisted
chaotic inflation with potential $\lambda\phi^4$ or $m^2\phi^2$ can not be
eternal. The effective field theory description for the inflaton field breaks
down before inflation reaches the eternal regime. We also find that the total
number of e-folds is still bounded by the inflationary entropy for the assisted
inflation.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 00:17:29 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Huang",
"Qing-Guo",
""
],
[
"Li",
"Miao",
""
],
[
"Wang",
"Yi",
""
]
] |
0707.3472 | Hiroshi Koibuchi | Hiroshi Koibuchi | Phase transition of meshwork models for spherical membranes | 21 pages, 12 figures | J. Stat. Phys. Vol.129, 605-621 (2007) | 10.1007/s10955-007-9385-y | ICT-Koi-2007-5 | cond-mat.stat-mech cond-mat.soft | null | We have studied two types of meshwork models by using the canonical Monte
Carlo simulation technique. The first meshwork model has elastic junctions,
which are composed of vertices, bonds, and triangles, while the second model
has rigid junctions, which are hexagonal (or pentagonal) rigid plates.
Two-dimensional elasticity is assumed only at the elastic junctions in the
first model, and no two-dimensional bending elasticity is assumed in the second
model. Both of the meshworks are of spherical topology. We find that both
models undergo a first-order collapsing transition between the smooth spherical
phase and the collapsed phase. The Hausdorff dimension of the smooth phase is
H\simeq 2 in both models as expected. It is also found that H\simeq 2 in the
collapsed phase of the second model, and that H is relatively larger than 2 in
the collapsed phase of the first model, but it remains in the physical bound,
i.e., H<3. Moreover, the first model undergoes a discontinuous surface
fluctuation transition at the same transition point as that of the collapsing
transition, while the second model undergoes a continuous transition of surface
fluctuation. This indicates that the phase structure of the meshwork model is
weakly dependent on the elasticity at the junctions.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 00:27:30 GMT"
}
] | 2007-10-25T00:00:00 | [
[
"Koibuchi",
"Hiroshi",
""
]
] |
0707.3473 | Derrick Hart | Derrick Hart, Alex Iosevich, Doowon Koh, Misha Rudnev | Averages over hyperplanes, sum-product theory in vector spaces over
finite fields and the Erdos-Falconer distance conjecture | null | null | null | null | math.CA math.CO | null | We prove a point-wise and average bound for the number of incidences between
points and hyper-planes in vector spaces over finite fields. While our
estimates are, in general, sharp, we observe an improvement for product sets
and sets contained in a sphere. We use these incidence bounds to obtain
significant improvements on the arithmetic problem of covering ${\mathbb F}_q$,
the finite field with q elements, by $A \cdot A+... +A \cdot A$, where A is a
subset ${\mathbb F}_q$ of sufficiently large size. We also use the incidence
machinery we develope and arithmetic constructions to study the Erdos-Falconer
distance conjecture in vector spaces over finite fields. We prove that the
natural analog of the Euclidean Erdos-Falconer distance conjecture does not
hold in this setting due to the influence of the arithmetic. On the positive
side, we obtain good exponents for the Erdos -Falconer distance problem for
subsets of the unit sphere in $\mathbb F_q^d$ and discuss their sharpness. This
results in a reasonably complete description of the Erdos-Falconer distance
problem in higher dimensional vector spaces over general finite fields.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 00:29:25 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Jul 2007 14:07:50 GMT"
}
] | 2007-07-31T00:00:00 | [
[
"Hart",
"Derrick",
""
],
[
"Iosevich",
"Alex",
""
],
[
"Koh",
"Doowon",
""
],
[
"Rudnev",
"Misha",
""
]
] |
0707.3474 | Wei-Qin Zhao | Zhao Wei-Qin | Groundstate with Zero Eigenvalue for Generalized Sombrero-shaped
Potential in $N$-dimensional Space | 8 pages, 3 figures | null | 10.1088/0253-6102/50/1/30 | null | quant-ph | null | Based on an iterative method for solving the goundstate of Schroedinger
equation, it is found that a kind of generalized Sombrero-shaped potentials in
N-dimensional space has groundstates with zero eigenvalue. The restrictions on
the parameters in the potential are discussed.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 01:10:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Wei-Qin",
"Zhao",
""
]
] |
0707.3475 | Vladimir V. Usov | A. E. Shabad, V. V. Usov | Electric field of a pointlike charge in a strong magnetic field and
ground state of a hydrogenlike atom | 45 pages, 6 figures, accepted to Phys. Rev. D | Phys.Rev.D77:025001,2008 | 10.1103/PhysRevD.77.025001 | null | astro-ph gr-qc hep-lat hep-ph hep-th physics.atom-ph | null | In an external constant magnetic field, so strong that the electron Larmour
length is much shorter than its Compton length, we consider the modification of
the Coulomb potential of a point charge owing to the vacuum polarization. We
establish a short-range component of the static interaction in the Larmour
scale, expressed as a Yukawa-like law, and reveal the corresponding "photon
mass" parameter. The electrostatic force regains its long-range character in
the Compton scale: the tail of the potential follows an anisotropic Coulomb
law, decreasing away from the charge slower along the magnetic field and faster
across. In the infinite-magnetic-field limit the potential is confined to an
infinitely thin string passing though the charge parallel to the external
field. This is the first evidence for dimensional reduction in the photon
sector of quantum electrodynamics. The one-dimensional form of the potential on
the string is derived that includes a delta-function centered in the charge.
The nonrelativistic ground-state energy of a hydrogenlike atom is found with
its use and shown not to be infinite in the infinite-field limit, contrary to
what was commonly accepted before, when the vacuum polarization had been
ignored. These results may be useful for studying properties of matter at the
surface of extremely magnetized neutron stars.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 02:52:54 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Sep 2007 10:23:26 GMT"
},
{
"version": "v3",
"created": "Mon, 29 Oct 2007 16:00:17 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Shabad",
"A. E.",
""
],
[
"Usov",
"V. V.",
""
]
] |
0707.3476 | Melvyn B. Nathanson | Sergei V. Konyagin and Melvyn B. Nathanson | Sums of products of congruence classes and of arithmetic progressions | 8 pages | International Journal of Number Theory 5 (2009), 625--634 | null | null | math.NT | null | Consider the congruence class R_m(a)={a+im:i\in Z} and the infinite
arithmetic progression P_m(a)={a+im:i\in N_0}. For positive integers a,b,c,d,m
the sum of products set R_m(a)R_m(b)+R_m(c)R_m(d) consists of all integers of
the form (a+im)(b+jm)+(c+km)(d+\ell m) for some i,j,k,\ell\in Z. It is proved
that if gcd(a,b,c,d,m)=1, then R_m(a)R_m(b)+R_m(c)R_m(d) is equal to the
congruence class R_m(ab+cd), and that the sum of products set
P_m(a)P_m(b)+P_m(c)P_m(d) eventually coincides with the infinite arithmetic
progression P_m(ab+cd).
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 02:09:31 GMT"
}
] | 2016-12-30T00:00:00 | [
[
"Konyagin",
"Sergei V.",
""
],
[
"Nathanson",
"Melvyn B.",
""
]
] |
0707.3477 | Michel Gingras | Taras Yavors'kii, Tom Fennell, Michel J. P. Gingras, Steven T.
Bramwell | Dy2Ti2O7 Spin Ice: a Test Case for Emergent Clusters in a Frustrated
Magnet | 4 pages, 2 figures. Conforms to published version. Small amendments
compared to version #1. A high resolution version of Figure 1 can be obtained
by e-mailing [email protected] | Phys. Rev. Lett. 101, 037204 (2008) | 10.1103/PhysRevLett.101.037204 | null | cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Dy2Ti2O7 is a geometrically frustrated magnetic material with a strongly
correlated spin ice regime that extends from 1 K down to as low as 60 mK. The
diffuse elastic neutron scattering intensities in the spin ice regime can be
remarkably well described by a phenomenological model of weakly interacting
hexagonal spin clusters, as invoked in other geometrically frustrated magnets.
We present a highly refined microscopic theory of Dy2Ti2O7 that includes
long-range dipolar and exchange interactions to third nearest neighbors and
which demonstrates that the clusters are purely fictitious in this material.
The seeming emergence of composite spin clusters and their associated
scattering pattern is instead an indicator of fine-tuning of ancillary
correlations within a strongly correlated state.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 03:16:47 GMT"
},
{
"version": "v2",
"created": "Fri, 1 Aug 2008 21:29:59 GMT"
}
] | 2008-08-02T00:00:00 | [
[
"Yavors'kii",
"Taras",
""
],
[
"Fennell",
"Tom",
""
],
[
"Gingras",
"Michel J. P.",
""
],
[
"Bramwell",
"Steven T.",
""
]
] |
0707.3478 | Rudi Schaefer | Rudi Sch\"afer, Markus Sj\"olin, Andreas Sundin, Michal Wolanski and
Thomas Guhr | Credit risk - A structural model with jumps and correlations | 24 pages | Physica A 383, 533 (2007) | 10.1016/j.physa.2007.04.053 | null | q-fin.RM cond-mat.stat-mech physics.soc-ph q-fin.ST | null | We set up a structural model to study credit risk for a portfolio containing
several or many credit contracts. The model is based on a jump--diffusion
process for the risk factors, i.e. for the company assets. We also include
correlations between the companies. We discuss that models of this type have
much in common with other problems in statistical physics and in the theory of
complex systems. We study a simplified version of our model analytically.
Furthermore, we perform extensive numerical simulations for the full model. The
observables are the loss distribution of the credit portfolio, its moments and
other quantities derived thereof. We compile detailed information about the
parameter dependence of these observables. In the course of setting up and
analyzing our model, we also give a review of credit risk modeling for a
physics audience.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 14:10:57 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Jul 2007 13:30:40 GMT"
}
] | 2008-12-02T00:00:00 | [
[
"Schäfer",
"Rudi",
""
],
[
"Sjölin",
"Markus",
""
],
[
"Sundin",
"Andreas",
""
],
[
"Wolanski",
"Michal",
""
],
[
"Guhr",
"Thomas",
""
]
] |
0707.3479 | Alp Atici | Alp Atici, Rocco A. Servedio | Quantum Algorithms for Learning and Testing Juntas | 15 pages, 1 figure. Uses synttree package. To appear in Quantum
Information Processing | Quantum Information Processing, Vol. 6, No. 5, 323 - 348 (2007) | 10.1007/s11128-007-0061-6 | null | quant-ph cs.LG | null | In this article we develop quantum algorithms for learning and testing
juntas, i.e. Boolean functions which depend only on an unknown set of k out of
n input variables. Our aim is to develop efficient algorithms:
- whose sample complexity has no dependence on n, the dimension of the domain
the Boolean functions are defined over;
- with no access to any classical or quantum membership ("black-box")
queries. Instead, our algorithms use only classical examples generated
uniformly at random and fixed quantum superpositions of such classical
examples;
- which require only a few quantum examples but possibly many classical
random examples (which are considered quite "cheap" relative to quantum
examples).
Our quantum algorithms are based on a subroutine FS which enables sampling
according to the Fourier spectrum of f; the FS subroutine was used in earlier
work of Bshouty and Jackson on quantum learning. Our results are as follows:
- We give an algorithm for testing k-juntas to accuracy $\epsilon$ that uses
$O(k/\epsilon)$ quantum examples. This improves on the number of examples used
by the best known classical algorithm.
- We establish the following lower bound: any FS-based k-junta testing
algorithm requires $\Omega(\sqrt{k})$ queries.
- We give an algorithm for learning $k$-juntas to accuracy $\epsilon$ that
uses $O(\epsilon^{-1} k\log k)$ quantum examples and $O(2^k \log(1/\epsilon))$
random examples. We show that this learning algorithms is close to optimal by
giving a related lower bound.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 13:17:55 GMT"
}
] | 2007-10-16T00:00:00 | [
[
"Atici",
"Alp",
""
],
[
"Servedio",
"Rocco A.",
""
]
] |
0707.3480 | Jean Chiar | J. E. Chiar, K. Ennico, Y. J. Pendleton, A. C. A. Boogert, T. Greene,
C. Knez, C. Lada, T. Roellig, A. G. G. M. Tielens, M. Werner, D. C. B.
Whittet | The Relationship between the Optical Depth of the 9.7 micron Silicate
Absorption Feature and Infrared Differential Extinction in Dense Clouds | 11 pages including 2 figures, 1 table. Accepted for publication in
ApJ Letters, 23 July 2007 | null | 10.1086/521789 | null | astro-ph | null | We have examined the relationship between the optical depth of the 9.7 micron
silicate absorption feature (tau_9.7) and the near-infrared color excess,
E(J-Ks) in the Serpens, Taurus, IC 5146, Chameleon I, Barnard 59, and Barnard
68 dense clouds/cores. Our data set, based largely on Spitzer IRS spectra,
spans E(J-Ks)=0.3 to 10 mag (corresponding to visual extinction between about 2
and 60 mag.). All lines of sight show the 9.7 micron silicate feature. Unlike
in the diffuse ISM where a tight linear correlation between the 9.7 micron
silicate feature optical depth and the extinction (Av) is observed, we find
that the silicate feature in dense clouds does not show a monotonic increase
with extinction. Thus, in dense clouds, tau_9.7 is not a good measure of total
dust column density. With few exceptions, the measured tau_9.7 values fall well
below the diffuse ISM correlation line for E(J-Ks) > 2 mag (Av >12 mag). Grain
growth via coagulation is a likely cause of this effect.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 04:27:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chiar",
"J. E.",
""
],
[
"Ennico",
"K.",
""
],
[
"Pendleton",
"Y. J.",
""
],
[
"Boogert",
"A. C. A.",
""
],
[
"Greene",
"T.",
""
],
[
"Knez",
"C.",
""
],
[
"Lada",
"C.",
""
],
[
"Roellig",
"T.",
""
],
[
"Tielens",
"A. G. G. M.",
""
],
[
"Werner",
"M.",
""
],
[
"Whittet",
"D. C. B.",
""
]
] |
0707.3481 | Daniel Chan | Daniel Chan | McKay correspondence for canonical orders | null | null | null | null | math.AG math.RA | null | Canonical orders, introduced in the minimal model program for orders, are
simultaneous generalisations of Kleinian singularities and their associated
skew group rings. In this paper, we construct minimal resolutions of canonical
orders via non-commutative cyclic covers and skew group rings. This allows us
to exhibit a derived equivalence between minimal resolutions of canonical
orders and the skew group ring form of the canonical order in all but one case.
The Fourier-Mukai transform used to construct this equivalence allows us to
make explicit, the numerical version of the McKay correspondence for canonical
orders which, relates the exceptional curves of the minimal resolution to the
indecomposable reflexive modules of the canonical order.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 04:51:06 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Chan",
"Daniel",
""
]
] |
0707.3482 | Kenton K. Yee | Kenton K. Yee | A Bayesian Framework for Combining Valuation Estimates | Citations at
http://papers.ssrn.com/sol3/cf_dev/AbsByAuth.cfm?per_id=240309 Review of
Quantitative Finance and Accounting, 30.3 (2008) forthcoming | null | null | null | q-fin.ST cs.CE nlin.AO nlin.CD nlin.SI physics.pop-ph physics.soc-ph stat.AP | null | Obtaining more accurate equity value estimates is the starting point for
stock selection, value-based indexing in a noisy market, and beating benchmark
indices through tactical style rotation. Unfortunately, discounted cash flow,
method of comparables, and fundamental analysis typically yield discrepant
valuation estimates. Moreover, the valuation estimates typically disagree with
market price. Can one form a superior valuation estimate by averaging over the
individual estimates, including market price? This article suggests a Bayesian
framework for combining two or more estimates into a superior valuation
estimate. The framework justifies the common practice of averaging over several
estimates to arrive at a final point estimate.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:04:53 GMT"
}
] | 2008-12-02T00:00:00 | [
[
"Yee",
"Kenton K.",
""
]
] |
0707.3483 | Guilhem Lavaux | G. Lavaux, R. Mohayaee, S. Colombi, R. B. Tully, F. Bernardeau, J.
Silk | Observational biases in Lagrangian reconstructions of cosmic velocity
fields | 29 pages, 21 figures, 6 tables, Accepted by MNRAS on 2007 October 2.
Received 2007 September 30; in original form 2007 July 24 | null | 10.1111/j.1365-2966.2007.12539.x | null | astro-ph | null | Lagrangian reconstruction of large-scale peculiar velocity fields can be
strongly affected by observational biases. We develop a thorough analysis of
these systematic effects by relying on specially selected mock catalogues. For
the purpose of this paper, we use the MAK reconstruction method, although any
other Lagrangian reconstruction method should be sensitive to the same
problems. We extensively study the uncertainty in the mass-to-light assignment
due to luminosity incompleteness, and the poorly-determined relation between
mass and luminosity. The impact of redshift distortion corrections is analyzed
in the context of MAK and we check the importance of edge and finite-volume
effects on the reconstructed velocities. Using three mock catalogues with
different average densities, we also study the effect of cosmic variance. In
particular, one of them presents the same global features as found in
observational catalogues that extend to 80 Mpc/h scales. We give recipes,
checked using the aforementioned mock catalogues, to handle these particular
observational effects, after having introduced them into the mock catalogues so
as to quantitatively mimic the most densely sampled currently available galaxy
catalogue of the nearby universe. Once biases have been taken care of, the
typical resulting error in reconstructed velocities is typically about a
quarter of the overall velocity dispersion, and without significant bias. We
finally model our reconstruction errors to propose an improved Bayesian
approach to measure Omega_m in an unbiased way by comparing the reconstructed
velocities to the measured ones in distance space, even though they may be
plagued by large errors. We show that, in the context of observational data, a
nearly unbiased estimator of Omega_m may be built using MAK reconstruction.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:15:20 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Jul 2007 01:06:52 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Oct 2007 08:38:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lavaux",
"G.",
""
],
[
"Mohayaee",
"R.",
""
],
[
"Colombi",
"S.",
""
],
[
"Tully",
"R. B.",
""
],
[
"Bernardeau",
"F.",
""
],
[
"Silk",
"J.",
""
]
] |
0707.3484 | Bei Jia | Bei Jia and Xi-Guo Lee | Small Cosmological Constants from a Modified Randall-Sundrum Model | 6 pages | null | null | null | hep-th | null | We study a mechanism, inspired from the mechanism for generating the gauge
hierarchy in Randall-Sundrum model, to investigate the cosmological constant
problem. First we analyze the bulk cosmological constant and brane vacuum
energies in RS model. We show that the five-dimensional bulk cosmological
constant and the vacuum energies of the two branes all obtain their natural
values. Finally we argue how we can generate a small four-dimensional effective
cosmological constant on the branes through modifying the original RS model.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:22:30 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Oct 2007 02:17:23 GMT"
}
] | 2007-10-18T00:00:00 | [
[
"Jia",
"Bei",
""
],
[
"Lee",
"Xi-Guo",
""
]
] |
0707.3485 | Kuntal Misra | Kuntal Misra (1), Dave Pooley (2), Poonam Chandra (3,4), D.
Bhattacharya (5), Alak K. Ray (6), Ram Sagar (1), Walter H. G. Lewin (7) ((1)
Aryabhatta Research Institute of Observational Sciences, Manora Peak,
Nainital, India, (2) Astronomy Department, University of California at
Berkeley, Berkeley (3) National Radio Astronomy Observatory, Charlottesville
(4) University of Virginia, Charlottesville (5) Raman Research Institute,
Bangalore, India, (6) Tata Institute of Fundamental Research, Homi Bhabha
Road, Mumbai, India, (7) Center for Space Research and Department of Physics,
Massachusetts Institute of Technology, Cambridge) | Type IIP Supernova SN 2004et: A Multi-Wavelength Study in X-Ray, Optical
and Radio | 13 Figures, Accepted for Publication in MNRAS | null | 10.1111/j.1365-2966.2007.12258.x | null | astro-ph | null | We present X-ray, broad band optical and low frequency radio observations of
the bright type IIP supernova SN 2004et. The \cxo observed the supernova at
three epochs, and the optical coverage spans a period of $\sim$ 470 days since
explosion. The X-ray emission softens with time, and we characterise the X-ray
luminosity evolution as $\Lx \propto t^{-0.4}$. We use the observed X-ray
luminosity to estimate a mass-loss rate for the progenitor star of $\sim
\ee{2}{-6} M_\odot \mathrm{yr}^{-1}$. The optical light curve shows a
pronounced plateau lasting for about 110 days. Temporal evolution of
photospheric radius and color temperature during the plateau phase is
determined by making black body fits. We estimate the ejected mass of $^{56}$Ni
to be 0.06 $\pm$ 0.03 M$_\odot$. Using the expressions of Litvinova &
Nad\"{e}zhin (1985) we estimate an explosion energy of (0.98 $\pm$ 0.25)
$\times 10^{51}$ erg. We also present a single epoch radio observation of SN
2004et. We compare this with the predictions of the model proposed by Chevalier
et al. (2006). These multi-wavelength studies suggest a main sequence
progenitor mass of $\sim$ 20 M$_\odot$ for SN 2004et.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:24:49 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Misra",
"Kuntal",
""
],
[
"Pooley",
"Dave",
""
],
[
"Chandra",
"Poonam",
""
],
[
"Bhattacharya",
"D.",
""
],
[
"Ray",
"Alak K.",
""
],
[
"Sagar",
"Ram",
""
],
[
"Lewin",
"Walter H. G.",
""
]
] |
0707.3486 | Mark Goresky | Mark Goresky, Nancy Hingston | Loop Products and Closed Geodesics | 63 pages | Duke Math. J. 150, no. 1 (2009), 117-209 | 10.1215/00127094-2009-049 | null | math.AT math.DG | null | We show the Chas-Sullivan product (on the homology of the free loop space of
a Riemannian manifold) is related to the Morse index of its closed geodesics.
We construct related products in the cohomology of the free loop space and of
the based loop space, and show they are nontrivial.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:54:51 GMT"
}
] | 2019-12-19T00:00:00 | [
[
"Goresky",
"Mark",
""
],
[
"Hingston",
"Nancy",
""
]
] |
0707.3487 | Ward Struyve | W. Struyve, H. Westman | A minimalist pilot-wave model for quantum electrodynamics | LaTex, 17 pages, no figures; v2 minor corrections, journal version | Proc. R. Soc. A 463, 3115-3129 (2007) | 10.1098/rspa.2007.0144 | null | quant-ph hep-th | null | We present a way to construct a pilot-wave model for quantum electrodynamics.
The idea is to introduce beables corresponding only to the bosonic degrees of
freedom and not to the fermionic degrees of freedom of the quantum state. We
show that this is sufficient to reproduce the quantum predictions. The beables
will be field beables corresponding to the electromagnetic field and they will
be introduced in a similar way to that of Bohm's model for the free
electromagnetic field. Our approach is analogous to the situation in
non-relativistic quantum theory, where Bell treated spin not as a beable but
only as a property of the wavefunction. After presenting this model we also
discuss a simple way for introducing additional beables that represent the
fermionic degrees of freedom.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 05:56:06 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Dec 2007 14:58:55 GMT"
}
] | 2008-04-09T00:00:00 | [
[
"Struyve",
"W.",
""
],
[
"Westman",
"H.",
""
]
] |
0707.3488 | Arvind Rajaraman | Jason Kumar, Arvind Rajaraman, James D. Wells | Probing the Green-Schwarz Mechanism at the Large Hadron Collider | 14 pages, references added | Phys.Rev.D77:066011,2008 | 10.1103/PhysRevD.77.066011 | null | hep-ph | null | We investigate the phenomenology of new abelian gauge bosons, which we denote
as $X$ bosons, that suffer a mixed anomaly with the Standard Model, but are
made self-consistent by the Green-Schwarz mechanism. A distinguishing aspect of
the resulting effective theory is the decay of $X$ bosons into Standard Model
gauge bosons, $X\to ZZ, WW, \gamma Z$. We compute the production cross-section
of the $X$ boson from vector boson fusion at the Large Hadron Collider. We
study the $pp\to X\to ZZ\to 4l$ signal, and analyze the prospects of discovery.
We argue that such a discovery could indirectly probe high energies, even up to
the string scale.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 06:04:46 GMT"
},
{
"version": "v2",
"created": "Thu, 15 Nov 2007 04:57:13 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kumar",
"Jason",
""
],
[
"Rajaraman",
"Arvind",
""
],
[
"Wells",
"James D.",
""
]
] |
0707.3489 | Gregory Arone | Gregory Arone | Derivatives of embedding functors I: the stable case | 58 pages, 1 figure. This is a major rewrite of the previously posted
version. The proof has been thoroughly reorganized, and we hope it has become
simpler and more direct (the new version is 17 pages shorter than the
previous one) | null | 10.1112/jtopol/jtp019 | null | math.AT | null | For smooth manifolds $M$ and $N$, let $\Ebar(M, N)$ be the homotopy fiber of
the map $\Emb(M, N)\longrightarrow \Imm(M, N)$. Consider the functor from the
category of Euclidean spaces to the category of spectra, defined by the formula
$V\mapsto \Sigma^\infty\Ebar(M, N\times V)$. In this paper, we describe the
Taylor polynomials of this functor, in the sense of M. Weiss' orthogonal
calculus, in the case when $N$ is a nice open submanifold of a Euclidean space.
This leads to a description of the derivatives of this functor when $N$ is a
tame stably parallelizable manifold (we believe that the parallelizability
assumption is not essential). Our construction involves a certain space of
rooted forests (or, equivalently, a space of partitions) with leaves marked by
points in $M$, and a certain ``homotopy bundle of spectra'' over this space of
trees. The $n$-th derivative is then described as the ``spectrum of restricted
sections'' of this bundle. This is the first in a series of two papers. In the
second part, we will give an analogous description of the derivatives of the
functor $\Ebar(M, N\times V)$, involving a similar construction with certain
spaces of connected graphs (instead of forests) with points marked in $M$.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:09:05 GMT"
},
{
"version": "v2",
"created": "Mon, 28 Apr 2008 15:52:35 GMT"
}
] | 2014-02-26T00:00:00 | [
[
"Arone",
"Gregory",
""
]
] |
0707.3490 | Anatoly Panchenkov N | A. N. Panchenkov | Econophysics and Financial-Economic Monitoring | 23 pages | null | null | TN-1-5-17.01.07 | physics.soc-ph | null | The author solves two problems: formation of object of econophysics, creation
of the general theory of financial-economic monitoring. In the first problem he
studied two fundamental tasks: a choice of conceptual model and creation of
axiomatic base. It is accepted, that the conceptual model of econophysics is a
concrete definition of entropy conceptual model. Financial and economic
monitoring is considered as monitoring of flows on entropy manifold of phase
space - on a Diffusion field.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 06:38:02 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Panchenkov",
"A. N.",
""
]
] |
0707.3491 | Jolanta Brodzicka | J. Brodzicka, H. Palka, et al (for the Belle Collaboration) | Observation of a new D_sJ meson in B+->D0BD0K+ decays | submitted to Phys. Rev. Lett | Phys.Rev.Lett.100:092001, 2008 | 10.1103/PhysRevLett.100.092001 | null | hep-ex | null | We report the observation of a new $D_{sJ}$ meson produced in $B^{+} \to
\bar{D}^{0} D_{sJ} \to \bar{D}^{0} D^{0} K^{+}$. This state has a mass of
$M=2708 \pm 9 ^{+11}_{-10} \rm{MeV}/{\it c}^{2}$, a width $\Gamma = 108 \pm 23
^{+36}_{-31} ~\rm{MeV}/ {\it c}^{2}$ and a $1^{-}$ spin-parity. The results are
based on an analysis of 449 million $B\bar{B}$ events collected at the
$\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy
$e^{+} e^{-}$ collider.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:05:04 GMT"
},
{
"version": "v2",
"created": "Fri, 1 Feb 2008 07:56:53 GMT"
}
] | 2019-08-13T00:00:00 | [
[
"Brodzicka",
"J.",
""
],
[
"Palka",
"H.",
""
]
] |
0707.3492 | Sergei Gninenko | S. N. Gninenko | Limit on the electric charge-nonconserving $\mu^+ \to invisible$ decay | 5 pages, 2 Figure, to appear in PRD | Phys.Rev.D76:055004,2007 | 10.1103/PhysRevD.76.055004 | null | hep-ph hep-ex | null | The first limit on the branching ratio of the electric charge-nonconserving
invisible muon decay $Br(\mu^+ \to invisible) < 5.2 \times 10^{-3}$ is obtained
from the recently reported results on new determination of the Fermi constant
from muon decays. The results of a feasibility study of a new proposed
experiment for a sensitive search for this decay mode at the level of a few
parts in 10^{11} are presented. Constrains on the $\tau \to invisible$ decay
rate are discussed. These leptonic charge-nonconserving processes may hold in
four-dimensional world in models with infinite extra dimensions, thus making
their searches complementary to collider experiments probing new physics.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 14:21:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gninenko",
"S. N.",
""
]
] |
0707.3493 | Behrouz Mirza | A. Akhtari Zavareh, A. Hojjati, B. Mirza | Generation of large scale magnetic fields by coupling to curvature and
dilaton field | 22 pages | Prog.Theor.Phys.117:803-822,2007 | 10.1143/PTP.117.803 | null | astro-ph | null | We investigate the generation of large scale magnetic fields in the universe
from quantum fluctuations produced in the inflationary stage. By coupling these
quantum fluctuations to the dilaton field and Ricci scalar, we show that the
magnetic fields with the strength observed today can be produced. We consider
two situations: First, the evolution of dilaton ends at the onset of the
reheating stage. Second, the dilaton continues its evolution after reheating
and then decays. In both cases, we come back to the usual Maxwell equations
after inflation and then calculate present magnetic fields.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:18:28 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zavareh",
"A. Akhtari",
""
],
[
"Hojjati",
"A.",
""
],
[
"Mirza",
"B.",
""
]
] |
0707.3494 | Urs Wiedemann A | Sebastian Sapeta, Urs Achim Wiedemann | Jet hadrochemistry as a characteristics of jet quenching | 15 pages, 7 figures, LaTex | Eur.Phys.J.C55:293-302,2008 | 10.1140/epjc/s10052-008-0592-8 | CERN-PH-TH/2007-111 | hep-ph | null | Jets produced in nucleus-nucleus collisions at the LHC are expected to be
strongly modified due to the interaction of the parton shower with the dense
QCD matter. Here, we point out that jet quenching can leave signatures not only
in the longitudinal and transverse jet energy and multiplicity distributions,
but also in the hadrochemical composition of the jet fragments. In particular,
we show that even in the absence of medium effects at or after hadronization,
the medium-modification of the parton shower can result in significant changes
in jet hadrochemistry. We discuss how jet hadrochemistry can be studied within
the high-multiplicity environment of nucleus-nucleus collisions at the LHC.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:27:25 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Sapeta",
"Sebastian",
""
],
[
"Wiedemann",
"Urs Achim",
""
]
] |
0707.3495 | Jiwen Zeng | Zeng Jiwen | Decomposition of Cartan Matrix and conjectures on Brauer character
degrees | 16 pages, changed contents and title | null | null | null | math.GR math.RT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let $G$ be a finite group and $N$ be a normal subgroup of $G$. Let
$J=J(F[N])$ denote the Jacboson radical of $F[N]$ and $I={\rm Ann}(J)=\{\alpha
\in F[G]|J\alpha =0\}$. We have another algebra $F[G]/I$. We study the
decomposition of Cartan matrix of $F[G]$ according to $F[G/N]$ and $F[G]/I$.
This decomposition establishs some connections between Cartan invariants and
chief composition factors of $G$. We find that existing zero-defect $p$-block
in $N$ depends on the properties of $I$ in $F[G]$ or Cartan invariants. When we
consider the Cartan invariants for a block algebra $B$ of $G$, the
decomposition is related to what kind of blocks in $N$ covered by $B$. We
mainly consider a block $B$ of $G$ which covers a block $b$ of $N$ with
$l(b)=1$. In two cases, we prove Willems' conjecture holds for these blocks,
which covers some true cases by Holm and Willems. Furthermore We give an
affirmative answer to a question by Holm and Willems in our cases. Some other
results about Cartan invariants are presented in our paper.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:34:52 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Oct 2008 07:37:14 GMT"
}
] | 2008-10-20T00:00:00 | [
[
"Jiwen",
"Zeng",
""
]
] |
0707.3496 | Kohei Ueno | Kohei Ueno | Dynamics of symmetric holomorphic maps on projective spaces | 12 pages | Publicacions Matematiques, 51 (2007), No. 2, 333-344 | null | null | math.DS | null | We consider complex dynamics of a critically finite holomorphic map from P^k
to P^k, which has symmetries associated with the symmetric group S_{k+2} acting
on P^k, for each k \ge 1. The Fatou set of each map of this family consists of
attractive basins of superattracting points. Each map of this family satisfies
Axiom A.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 15:06:48 GMT"
}
] | 2018-03-29T00:00:00 | [
[
"Ueno",
"Kohei",
""
]
] |
0707.3497 | Micha{\l} Stukow | Michal Stukow | Generating mapping class groups of nonorientable surfaces with boundary | null | Advances in Geometry 10/2 (2010), 249-273 | 10.1515/advgeom.2010.010 | null | math.GT | null | We obtain simple generating sets for various mapping class groups of a
nonorientable surface with punctures and/or boundary. We also compute the
abelianizations of these mapping class groups.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:50:59 GMT"
}
] | 2014-02-18T00:00:00 | [
[
"Stukow",
"Michal",
""
]
] |
0707.3498 | Chung-Hou Chung | Chung-Hou Chung, Gergely Zarand and Peter W\"olfle | Two-stage Kondo effect in side-coupled quantum dots: Renormalized
perturbative scaling theory and Numerical Renormalization Group analysis | 6 pages, 7 figures | null | 10.1103/PhysRevB.77.035120 | null | cond-mat.mes-hall cond-mat.str-el | null | We study numerically and analytically the dynamical (AC) conductance through
a two-dot system, where only one of the dots is coupled to the leads but it is
also side-coupled to the other dot through an antiferromagnetic exchange (RKKY)
interaction. In this case the RKKY interaction gives rise to a ``two-stage
Kondo effect'' where the two spins are screened by two consecutive Kondo
effects. We formulate a renormalized scaling theory that captures remarkably
well the cross-over from the strongly conductive correlated regime to the low
temperature low conductance state. Our analytical formulas agree well with our
numerical renormalization group results. The frequency dependent current noise
spectrum is also discussed.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 07:55:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chung",
"Chung-Hou",
""
],
[
"Zarand",
"Gergely",
""
],
[
"Wölfle",
"Peter",
""
]
] |
0707.3499 | Tim Van der Linden | Julia Goedecke and Tim Van der Linden | A comparison theorem for simplicial resolutions | 16 pages | J. Goedecke and T. Van der Linden, A comparison theorem for
simplicial resolutions, J. Homotopy and Related Structures 2 (2007), no. 1,
109-126 | null | null | math.AT math.CT | null | It is well known that Barr and Beck's definition of comonadic homology makes
sense also with a functor of coefficients taking values in a semi-abelian
category instead of an abelian one. The question arises whether such a homology
theory has the same convenient properties as in the abelian case. Here we focus
on independence of the chosen comonad: conditions for homology to depend on the
induced class of projectives only.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:23:43 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 11:50:22 GMT"
}
] | 2009-04-16T00:00:00 | [
[
"Goedecke",
"Julia",
""
],
[
"Van der Linden",
"Tim",
""
]
] |
0707.3500 | Andrey Chugunov Mr. | A.I. Chugunov (1), H.E. DeWitt (2), D.G. Yakovlev (1) ((1) Ioffe
Institute; (2) LLNL) | Coulomb tunneling for fusion reactions in dense matter: Path integral
Monte Carlo versus mean field | 13 pages, 7 figures, to appear in Phys. Rev. D | Phys.Rev.D76:025028,2007 | 10.1103/PhysRevD.76.025028 | null | astro-ph nucl-th | null | We compare Path Integral Monte Carlo calculations by Militzer and Pollock
(Phys. Rev. B 71, 134303, 2005) of Coulomb tunneling in nuclear reactions in
dense matter to semiclassical calculations assuming WKB Coulomb barrier
penetration through the radial mean-field potential. We find a very good
agreement of two approaches at temperatures higher than ~1/5 of the ion plasma
temperature. We obtain a simple parameterization of the mean field potential
and of the respective reaction rates. We analyze Gamow-peak energies of
reacting ions in various reaction regimes and discuss theoretical uncertainties
of nuclear reaction rates taking carbon burning in dense stellar matter as an
example.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:27:07 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chugunov",
"A. I.",
""
],
[
"DeWitt",
"H. E.",
""
],
[
"Yakovlev",
"D. G.",
""
]
] |
0707.3501 | Shiping Feng | Li Cheng and Shiping Feng | Doping and energy evolution of spin dynamics in the electron-doped
cuprate superconductor Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-\delta}$ | 8 pages, 4 figures, added discussions, replotted figures, and updated
references, accepted for publication in Phys. Rev. B | Phys. Rev. B 77, 054518 (2008) | 10.1103/PhysRevB.77.054518 | null | cond-mat.supr-con cond-mat.str-el | null | The doping and energy evolution of the magnetic excitations of the
electron-doped cuprate superconductor Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-\delta}$
in the superconducting state is studied based on the kinetic energy driven
superconducting mechanism. It is shown that there is a broad commensurate
scattering peak at low energy, then the resonance energy is located among this
low energy commensurate scattering range. This low energy commensurate
scattering disperses outward into a continuous ring-like incommensurate
scattering at high energy. The theory also predicts a dome shaped doping
dependent resonance energy.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:27:23 GMT"
},
{
"version": "v2",
"created": "Thu, 14 Feb 2008 01:41:38 GMT"
}
] | 2008-02-28T00:00:00 | [
[
"Cheng",
"Li",
""
],
[
"Feng",
"Shiping",
""
]
] |
0707.3502 | Luigi Foschini | Elena Pian (1), Luigi Foschini (2), Gabriele Ghisellini (3) ((1) INAF
- Trieste Astronomical Observatory, (2) INAF - IASF, Bologna, (3) INAF -
Brera Astronomical Observatory) | INTEGRAL and Swift Observations of Blazars in Outburst | 12 pages, 5 figures, Proceedings of the Frascati Workshop 2007
(Vulcano, May 28 - June 2, 2007) | null | null | null | astro-ph | null | The blazars 3C 454.3, PKS 0537-441 and PKS 2155-304 are traditionally known
to be among the most active sources of this class. They emit at all
frequencies, up to the gamma-rays, and are good probes of multiwavelength
nuclear variability. The first two have also luminous broad emission line
regions. We have recently monitored them with various facilities, including
Swift and INTEGRAL, and have interpreted their variations with models of
non-thermal radiation from a relativistic jet. In particular, we have tested
for the first two sources the hypothesis that the variability is produced
within the jet through internal shocks, i.e. collisions of relativistic plasma
blobs. This allows a parameterization of all physical quantities as functions
of the bulk Lorentz factor. We have made the critical assumption that every
flaring episode is characterized by a fixed amount of energy. The model
reproduces brilliantly the multiwavelength data and especially the gamma-ray
spectra, when available. The model is not applicable to PKS 2155-304, the
variability of which is caused by independent variations of few individual
parameters.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 12:43:56 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Pian",
"Elena",
""
],
[
"Foschini",
"Luigi",
""
],
[
"Ghisellini",
"Gabriele",
""
]
] |
0707.3503 | Poh-Boon Phua | P. B. Phua and W. J. Lai | Simple Coherent Polarization Manipulation Scheme for Generating High
Power Radially Polarized Beam | Submitting for publication | null | 10.1364/OE.15.014251 | null | physics.optics | null | We present a simple novel scheme that converts a Gaussian beam into an
approximated radially polarized beam using coherent polarization manipulation
together with Poynting walk-off in birefringent crystals. Our scheme alleviates
the interferometric stability required by previous schemes that implemented
this coherent mode summation using Mach-Zehnder-like interferometers. A
symmetrical arrangement of two walk-off crystals with a half-wave plate, allows
coherence control even when the laser has short temporal coherence length. We
generated 14 watts of radially polarized beam from an Ytterbium fiber laser,
only limited by the available fiber laser power.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:49:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Phua",
"P. B.",
""
],
[
"Lai",
"W. J.",
""
]
] |
0707.3504 | Nicolas Champagnat | Nicolas Champagnat (INRIA Sophia Antipolis / INRIA Lorraine / IECN),
Sylvie Roelly | Limit theorems for conditioned multitype Dawson-Watanabe processes and
Feller diffusions | null | Electronic Journal of Probability 13, 25 (2008) 777-810 | null | null | math.PR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A multitype Dawson-Watanabe process is conditioned, in subcritical and
critical cases, on non-extinction in the remote future. On every finite time
interval, its distribution is absolutely continuous with respect to the law of
the unconditioned process. A martingale problem characterization is also given.
Several results on the long time behavior of the conditioned mass process|the
conditioned multitype Feller branching diffusion are then proved. The general
case is first considered, where the mutation matrix which models the
interaction between the types, is irreducible. Several two-type models with
decomposable mutation matrices are analyzed too.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:50:43 GMT"
},
{
"version": "v2",
"created": "Tue, 9 Dec 2008 16:02:28 GMT"
}
] | 2011-12-05T00:00:00 | [
[
"Champagnat",
"Nicolas",
"",
"INRIA Sophia Antipolis / INRIA Lorraine / IECN"
],
[
"Roelly",
"Sylvie",
""
]
] |
0707.3505 | Melchior | A.-L. Melchior, F. Combes | Molecular content of a type-Ia SN host galaxy at z=0.6 | 8 pages, 7 figures, accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12261.x | null | astro-ph | null | We study the properties and the molecular content of the host of a type-Ia
supernova (SN1997ey). This z=0.575 host is the brightest submillimetre source
of the sample of type-Ia supernova hosts observed at 450um and 850um by Farrah
et al.. Observations were performed at IRAM-30m to search for CO(2-1) and
CO(3-2) lines in good weather conditions but no signal was detected. The star
formation rate cannot exceed 50 M_sol/yr. These negative results are confronted
with an optical analysis of a Keck spectrum and other data archives. We reach
the conclusion that this galaxy is a late-type system (0.7 L^B_*), with a small
residual star-formation activity (0.2 M_sol/yr) detected in the optical. No
source of heating (AGN or starburst) is found to explain the
submillimetre-continuum flux and the non-CO detection excludes the presence of
a large amount of cold gas. We thus suggest that either the star formation
activity is hidden in the nucleus (with A_V ~ 4) or this galaxy is passive or
anemic and this flux might be associated with a background galaxy.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 08:56:36 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Melchior",
"A. -L.",
""
],
[
"Combes",
"F.",
""
]
] |
0707.3506 | Frank Klinker | Frank Klinker | SUSY structures on deformed supermanifolds | 20 pages. v2 coincides with the version published in Differential
Geometry and its Applications | Differ. Geom. Appl. 26 (2008), 566-582 | 10.1016/j.difgeo.2007.11.036 | null | math.DG | null | We construct a geometric structure on deformed supermanifolds as a certain
subalgebra of the vector fields. In the classical limit we obtain a decoupling
of the infinitesimal odd and even transformations, whereas in the semiclassical
limit the result is a representation of the supersymmetry algebra. In the case
of mass preserving structure we describe all high energy corrections to this
algebra.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:07:43 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Mar 2008 11:19:31 GMT"
}
] | 2011-05-23T00:00:00 | [
[
"Klinker",
"Frank",
""
]
] |
0707.3507 | Damien Chablat | Daniel Kanaan (IRCCyN), Philippe Wenger (IRCCyN), Damien Chablat
(IRCCyN) | Workspace and Kinematic Analysis of the VERNE machine | null | Dans International Conference on Advanced Intelligent Mechatronics
- AIM, Z\"urich : Suisse (09/2007) | null | null | cs.RO | null | This paper describes the workspace and the inverse and direct kinematic
analysis of the VERNE machine, a serial/parallel 5-axis machine tool designed
by Fatronik for IRCCyN. This machine is composed of a three-degree-of-freedom
(DOF) parallel module and a two-DOF serial tilting table. The parallel module
consists of a moving platform that is connected to a fixed base by three
non-identical legs. This feature involves (i) a simultaneous combination of
rotation and translation for the moving platform, which is balanced by the
tilting table and (ii) workspace whose shape and volume vary as a function of
the tool length. This paper summarizes results obtained in the context of the
European projects NEXT ("Next Generation of Productions Systems").
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:13:22 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Kanaan",
"Daniel",
"",
"IRCCyN"
],
[
"Wenger",
"Philippe",
"",
"IRCCyN"
],
[
"Chablat",
"Damien",
"",
"IRCCyN"
]
] |
0707.3508 | Raphael Galicher | R. Galicher, P. Baudoz | Expected Performance of a Self-Coherent Camera | 6 pages, 4 figures | Comptes Rendus Physique 8:333-339,2007 | 10.1016/j.crhy.2007.03.004 | null | astro-ph | null | Residual wavefront errors in optical elements limit the performance of
coronagraphs. To improve their efficiency, different types of devices have been
proposed to correct or calibrate these errors. In this paper, we study one of
these techniques proposed by Baudoz et al. 2006 and called Self-Coherent Camera
(SCC). The principle of this instrument is based on the lack of coherence
between the stellar light and the planet that is searched for. After recalling
the principle of the SCC, we simulate its performance under realistic
conditions and compare it with the performance of differential imaging.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:18:46 GMT"
}
] | 2009-03-19T00:00:00 | [
[
"Galicher",
"R.",
""
],
[
"Baudoz",
"P.",
""
]
] |
0707.3509 | Laurent Decreusefond | Laurent Decreusefond (LTCI), Eduardo Ferraz (LTCI), Philippe Martins
(LTCI) | Upper bound of loss probability in an OFDMA system with randomly located
users | null | null | null | null | math.PR cs.IT cs.NI math.IT | null | For OFDMA systems, we find a rough but easily computed upper bound for the
probability of loosing communications by insufficient number of sub-channels on
downlink. We consider as random the positions of receiving users in the system
as well as the number of sub-channels dedicated to each one. We use recent
results of the theory of point processes which reduce our calculations to the
first and second moments of the total required number of sub-carriers.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 15:12:13 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Decreusefond",
"Laurent",
"",
"LTCI"
],
[
"Ferraz",
"Eduardo",
"",
"LTCI"
],
[
"Martins",
"Philippe",
"",
"LTCI"
]
] |
0707.3510 | A. D. Alhaidari | A. D. Alhaidari | Analytic solution of the Schrodinger equation for an electron in the
field of a molecule with an electric dipole moment | 20 pages, 1 figure, 4 tables | Ann. Phys. 323, 1709 (2008) | 10.1016/j.aop.2007.12.005 | null | physics.chem-ph math-ph math.MP physics.atom-ph | null | We relax the usual diagonal constraint on the matrix representation of the
eigenvalue wave equation by allowing it to be tridiagonal. This results in a
larger solution space that incorporates an exact analytic solution for the
non-central electric dipole potential cos(theta)/r^2, which was known not to
belong to the class of exactly solvable potentials. As a result, we were able
to obtain an exact analytic solution of the three-dimensional time-independent
Schrodinger equation for a charged particle in the field of a point electric
dipole that could carry a nonzero net charge. This problem models the
interaction of an electron with a molecule (neutral or ionized) that has a
permanent electric dipole moment. The solution is written as a series of square
integrable functions that support a tridiagonal matrix representation for the
angular and radial components of the wave operator. Moreover, this solution is
for all energies, the discrete (for bound states) as well as the continuous
(for scattering states). The expansion coefficients of the radial and angular
components of the wavefunction are written in terms of orthogonal polynomials
satisfying three-term recursion relations. For the Coulomb-free case, where the
molecule is neutral, we calculate critical values for its dipole moment below
which no electron capture is allowed. These critical values are obtained not
only for the ground state, where it agrees with already known results, but also
for excited states as well.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:20:20 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Alhaidari",
"A. D.",
""
]
] |
0707.3511 | Alberto Bernacchia | Alberto Bernacchia | Continuous or discrete attractors in neural circuits? A self-organized
switch at maximal entropy | 4 pages, 2 figures | null | null | null | physics.bio-ph | null | A recent experiment suggests that neural circuits may alternatively implement
continuous or discrete attractors, depending on the training set up. In
recurrent neural network models, continuous and discrete attractors are
separately modeled by distinct forms of synaptic prescriptions (learning
rules). Here, we report a solvable network model, endowed with Hebbian synaptic
plasticity, which is able to learn either discrete or continuous attractors,
depending on the frequency of presentation of stimuli and on the structure of
sensory coding. A continuous attractor is learned when experience matches
sensory coding, i.e. when the distribution of experienced stimuli matches the
distribution of preferred stimuli of neurons. In that case, there is no
processing of sensory information and neural activity displays maximal entropy.
If experience goes beyond sensory coding, processing is initiated and the
continuous attractor is destabilized into a set of discrete attractors.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:34:19 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Sep 2007 16:08:45 GMT"
}
] | 2007-09-04T00:00:00 | [
[
"Bernacchia",
"Alberto",
""
]
] |
0707.3512 | Ingemar Bengtsson | Ingemar Bengtsson | A Curious Geometrical Fact About Entanglement | Talk at the Vaxjo conference on Quantum Theory: Reconsideration of
Foundations - 4 | null | 10.1063/1.2827333 | null | quant-ph | null | I sketch how the set of pure quantum states forms a phase space, and then
point out a curiousity concerning maximally entangled pure states: they form a
minimal Lagrangian submanifold of the set of all pure states. I suggest that
this curiousity should have an interesting physical interpretation.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:34:39 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bengtsson",
"Ingemar",
""
]
] |
0707.3513 | Hongwu Liu | H. W. Liu, T. Fujisawa, Y. Ono, H. Inokawa, A. Fujiwara, K. Takashina,
Y. Hirayama | Pauli-Spin-Blockade Transport through a Silicon Double Quantum Dot | 10 pages,3 figures | Phys.Rev.B 77, 073310 (2008) | 10.1103/PhysRevB.77.073310 | null | cond-mat.mes-hall | null | We present measurements of resonant tunneling through discrete energy levels
of a silicon double quantum dot formed in a thin silicon-on-insulator layer. In
the absence of piezoelectric phonon coupling, spontaneous phonon emission with
deformation-potential coupling accounts for inelastic tunneling through the
ground states of the two dots. Such transport measurements enable us to observe
a Pauli spin blockade due to effective two-electron spin-triplet correlations,
evident in a distinct bias-polarity dependence of resonant tunneling through
the ground states. The blockade is lifted by the excited-state resonance by
virtue of efficient phonon emission between the ground states. Our experiment
demonstrates considerable potential for investigating silicon-based spin
dynamics and spin-based quantum information processing.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:41:04 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Feb 2008 01:05:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Liu",
"H. W.",
""
],
[
"Fujisawa",
"T.",
""
],
[
"Ono",
"Y.",
""
],
[
"Inokawa",
"H.",
""
],
[
"Fujiwara",
"A.",
""
],
[
"Takashina",
"K.",
""
],
[
"Hirayama",
"Y.",
""
]
] |
0707.3514 | Eve C. Ostriker | Christopher F. McKee and Eve C. Ostriker | Theory of Star Formation | 120 pages, to appear in ARAA. No changes from v1 text; permission
statement added | Ann.Rev.Astron.Astrophys.45:565-687,2007 | 10.1146/annurev.astro.45.051806.110602 | null | astro-ph | null | We review current understanding of star formation, outlining an overall
theoretical framework and the observations that motivate it. A conception of
star formation has emerged in which turbulence plays a dual role, both creating
overdensities to initiate gravitational contraction or collapse, and countering
the effects of gravity in these overdense regions. The key dynamical processes
involved in star formation -- turbulence, magnetic fields, and self-gravity --
are highly nonlinear and multidimensional. Physical arguments are used to
identify and explain the features and scalings involved in star formation, and
results from numerical simulations are used to quantify these effects. We
divide star formation into large-scale and small-scale regimes and review each
in turn. Large scales range from galaxies to giant molecular clouds (GMCs) and
their substructures. Important problems include how GMCs form and evolve, what
determines the star formation rate (SFR), and what determines the initial mass
function (IMF). Small scales range from dense cores to the protostellar systems
they beget. We discuss formation of both low- and high-mass stars, including
ongoing accretion. The development of winds and outflows is increasingly well
understood, as are the mechanisms governing angular momentum transport in
disks. Although outstanding questions remain, the framework is now in place to
build a comprehensive theory of star formation that will be tested by the next
generation of telescopes.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 15:30:43 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Jul 2007 21:45:04 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"McKee",
"Christopher F.",
""
],
[
"Ostriker",
"Eve C.",
""
]
] |
0707.3515 | A Khodam-Mohammadi | A. Khodam-Mohammadi | Charged Rotating Black Branes in Various Dimensions | PhD thesis, 130 pages and 23 figures. arXiv admin note: substantial
text overlap with arXiv:gr-qc/9610038 by other authors | null | null | null | hep-th | null | In this thesis, two different aspects of asymptotically charged rotating
black branes in various dimensions are studied. In the first part, the
thermodynamics of these spacetimes is investigated, while in the second part
the no hair theorem for these spacetimes in four dimensions is considered. In
part I, first, the Euclidean actions of a d-dimensional charged rotating black
brane are computed through the use of the counterterms renormalization method
both in the canonical and the grand-canonical ensemble, and it is shown that
the logarithmic divergencies associated to the Weyl anomalies and matter field
vanish. Second, a Smarr-type formula for the mass as a function of the entropy,
the angular momenta and the electric charge is obtained, which shows that these
quantities satisfy the first law of thermodynamics. Third, by using the
conserved quantities and the Euclidean actions, the thermodynamics potentials
of the system in terms of the temperature, the angular velocities and the
electric potential are obtained both in the canonical and the grand-canonical
ensemble. Fourth, a stability analysis in these two ensembles is performed,
which shows that the system is thermally stable. This is in commensurable with
the fact that there is no Hawking-Page phase transition for black object with
zero curvature horizon. Finally, the logarithmic correction of the entropy due
to the thermal fluctuation around the equilibrium is calculated. In part II,
the cosmological defects are studied, and it is shown that the Abelian Higgs
field equations in the background of a four-dimensional rotating charged black
string have vortex solutions.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 09:57:06 GMT"
}
] | 2014-08-02T00:00:00 | [
[
"Khodam-Mohammadi",
"A.",
""
]
] |
0707.3516 | Marcello Giroletti | M. Giroletti | Jet Properties and Evolution in Small and Intermediate Scale Objects | Invited talk; proceedings of "Extragalactic Jets", Girdwood, Alaska,
21-24 May, 2007; 10 pgs, uses customized asp2006.sty | null | null | null | astro-ph | null | Kinematic and spectral studies are improving our knowledge of the age
distribution in compact radio sources, providing evidence that small sources
are generally very young. The properties of jets in objects spanning the size
range from a few tens of parsecs to some kiloparsecs become then of particular
interest. Because of our selection criteria and of the small scales involved,
the properties of jets in the population of Compact Symmetric Objects (CSO) are
not well known yet. Polarization properties seem to indicate a strong influence
by the interaction with the dense surrounding medium, and some objects show
evidence of relativistic bulk motion. More evolved jets are present in the
class of Low Power Compact (LPC) sources and a number of cases are discussed
here. Since it is becoming increasingly clear that not all these sources will
survive to evolve into large scale radio galaxies, the question of the final
evolution of the CSO and LPC population is also discussed, with examples of
candidate dying sources.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:01:53 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Giroletti",
"M.",
""
]
] |
0707.3517 | Corneliu \c{S}ochichiu | Corneliu Sochichiu | On dilatation operator for a renormalizable theory | 26 pages, no figures | JHEP 0709:025,2007 | 10.1088/1126-6708/2007/09/025 | null | hep-th | null | Given a renormalizable theory we construct the dilatation operator, in the
sense of generator of RG flow of composite operators. The generator is found as
a differential operator acting on the space of normal symbols of composite
operators in the theory. In the spirit of AdS/CFT correspondence, this operator
is interpreted as the Hamiltonian of the dual theory. In the case of a field
theory with non-abelian gauge symmetry the resulting system is a matrix model.
The one-loop case is analyzed in details and it is shown that we reproduce
known results from N=4 supersymmetric Yang-Mills theory.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:19:21 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 09:00:33 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Sochichiu",
"Corneliu",
""
]
] |
0707.3518 | Jorge Garcia Rojas | Jorge Garcia-Rojas and Cesar Esteban (Instituto de Astrofisica de
Canarias, Spain) | On the abundance discrepancy problem in HII regions | 14 pages, 8 figures, 9 tables. Accepted for publication in the ApJ | null | 10.1086/521871 | null | astro-ph | null | The origin of the abundance discrepancy is one of the key problems in the
physics of photoionized nebula. In this work, we analize and discuss data for a
sample of Galactic and extragalactic HII regions where this abundance
discrepancy has been determined. We find that the abundance discrepancy factor
(ADF) is fairly constant and of the order of 2 in all the available sample of
HII regions. This is a rather different behaviour than that observed in
planetary nebulae, where the ADF shows a much wider range of values. We do not
find correlations between the ADF and the O/H, O++/H+ ratios, the ionization
degree, Te(High), Te(Low)/ Te(High), FWHM, and the effective temperature of the
main ionizing stars within the observational uncertainties. These results
indicate that whatever mechanism is producing the abundance discrepancy in HII
regions it does not substantially depend on those nebular parameters. On the
contrary, the ADF seems to be slightly dependent on the excitation energy, a
fact that is consistent with the predictions of the classical temperature
fluctuations paradigm. Finally, we obtain that Te values obtained from OII
recombination lines in HII regions are in agreement with those obtained from
collisionally excited line ratios, a behaviour that is again different from
that observed in planetary nebulae. These similar temperature determinations
are in contradiction with the predictions of the model based on the presence of
chemically inhomogeneous clumps but are consistent with the temperature
fluctuations paradigm. We conclude that all the indications suggest that the
physical mechanism responsible of the abundance discrepancy in HII regions and
planetary nebulae are different.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:23:43 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Garcia-Rojas",
"Jorge",
"",
"Instituto de Astrofisica de\n Canarias, Spain"
],
[
"Esteban",
"Cesar",
"",
"Instituto de Astrofisica de\n Canarias, Spain"
]
] |
0707.3519 | Camille Bonvin Mrs | Camille Bonvin, Ruth Durrer, Pedro G. Ferreira, Glenn Starkman and Tom
G. Zlosnik | Generalized Einstein-Aether theories and the Solar System | 16 pages, 1 figure, new appendix A on asymptotic flatness | Phys.Rev.D77:024037,2008 | 10.1103/PhysRevD.77.024037 | null | astro-ph | null | It has been shown that generalized Einstein-Aether theories may lead to
significant modifications to the non-relativistic limit of the Einstein
equations. In this paper we study the effect of a general class of such
theories on the Solar System. We consider corrections to the gravitational
potential in negative and positive powers of distance from the source. Using
measurements of the perihelion shift of Mercury and time delay of radar signals
to Cassini, we place constraints on these corrections. We find that a subclass
of generalized Einstein-Aether theories are compatible with these constraints.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:24:02 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Nov 2007 11:22:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bonvin",
"Camille",
""
],
[
"Durrer",
"Ruth",
""
],
[
"Ferreira",
"Pedro G.",
""
],
[
"Starkman",
"Glenn",
""
],
[
"Zlosnik",
"Tom G.",
""
]
] |
0707.3520 | Benedetta Ciardi | Benedetta Ciardi (MPA), Ruben Salvaterra (Milano Bicocca) | Lyalpha heating and its impact on early structure formation | 7 pages, 5 figures, to be printed in MNRAS | null | 10.1111/j.1365-2966.2007.12303.x | null | astro-ph | null | In this paper we have calculated the effect of Lyalpha photons emitted by the
first stars on the evolution of the IGM temperature. We have considered both a
standard Salpeter IMF and a delta-function IMF for very massive stars with mass
300 M_sun. We find that the Lyalpha photons produced by the stellar populations
considered here are able to heat the IGM at z<25, although never above ~100 K.
Stars with a Salpeter IMF are more effective as, due to the contribution from
small-mass long-living stars, they produce a higher Lyalpha background. Lyalpha
heating can affect the subsequent formation of small mass objects by producing
an entropy floor that may limit the amount of gas able to collapse and reduce
the gas clumping.We find that the gas fraction in halos of mass below ~ 5 x
10^6 M_sun is less than 50% (for the smallest masses this fraction drops to 1%
or less) compared to a case without Lyalpha heating. Finally, Lyalpha photons
heat the IGM temperature above the CMB temperature and render the 21cm line
from neutral hydrogen visible in emission at z<15.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:28:11 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ciardi",
"Benedetta",
"",
"MPA"
],
[
"Salvaterra",
"Ruben",
"",
"Milano Bicocca"
]
] |
0707.3521 | Erlend Forn{\ae}ss Wold | Stefan Borell, Frank Kutzschebauch, Erlend Fornaess Wold | Proper holomorphic disks in the complement of varieties in \C^2 | null | null | null | null | math.CV | null | For any closed analytic set X in C^2 there exists a proper holomorphic
embedding of the unit disk into C^2 such that the image avoids X.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:44:17 GMT"
}
] | 2007-07-25T00:00:00 | [
[
"Borell",
"Stefan",
""
],
[
"Kutzschebauch",
"Frank",
""
],
[
"Wold",
"Erlend Fornaess",
""
]
] |
0707.3522 | Olaf Lechtenfeld | Olaf Lechtenfeld | Supersymmetric noncommutative solitons | 13 pages, 2 figures; talk given during "Noncommutative Spacetime
Geometries" at Alessandria, March 2007, and "Noncommutative Geometry and
Physics" at Orsay, April 2007 | J.Phys.Conf.Ser.103:012016,2008 | 10.1088/1742-6596/103/1/012016 | null | hep-th | null | I consider a supersymmetric Bogomolny-type model in 2+1 dimensions
originating from topological string theory. By a gauge fixing this model is
reduced to a supersymmetric U(n) chiral model with a Wess-Zumino-Witten-type
term in 2+1 dimensions. After a noncommutative extension of the model, I employ
the dressing method to construct explicit multi-soliton configurations on
noncommutative R^{2,1|2N}.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:01:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lechtenfeld",
"Olaf",
""
]
] |
0707.3523 | Robert Eder | R. Eder | From cluster to solid - the variational cluster approximation applied to
NiO | Revtex, 4 pages, 2 eps-figures | null | 10.1103/PhysRevB.76.241103 | null | cond-mat.str-el | null | The variational cluster approximation is applied to the calculation of the
single particle spectral function of NiO. Trial self energies and the numerical
value of the Luttinger-Ward functional are obtained by exact diagonalization of
NiO6-clusters and the single particle parameters of the clusters serve as
variational parameters to obtain a stationary point of the grand potential of
the lattice system. Good agreement with experiment is obtained.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:02:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Eder",
"R.",
""
]
] |
0707.3524 | Anton Tikhonov Valerievich | Anton V. Tikhonov and Anatoly A. Klypin | Voids in the Local Volume: a limit on appearance of a galaxy in a DM
halo | 5 pages, 1 figure | Proceedings of "Dark Galaxies and Lost Barions" IAU Symposium 244,
2007 | 10.1017/S1743921307013944 | null | astro-ph | null | Current explanation of the overabundance of dark matter subhalos in the Local
Group (LG) indicates that there maybe a limit on mass of a halo, which can host
a galaxy. This idea can be tested using voids in the distribution of galaxies:
at some level small voids should not contain any (even dwarf) galaxies. We use
observational samples complete to M_B = -12 with distances less than 8 Mpc to
construct the void function (VF): the distribution of sizes of voids empty of
any galaxies. There are ~30 voids with sizes ranging from 1 to 5 Mpc. We then
study the distribution of dark matter halos in very high resolution simulations
of the LCDM model. The theoretical VF matches the observations remarkably well
only if we use halos with circular velocities larger than 45 +/- 10 km/s. This
agrees with the Local Group predictions. There are smaller halos in the voids,
but they should not produce any luminous matter. Small voids look quite similar
to their giant cousins: the density has a minimum at the center of a void and
it increases as we get closer to the border. Small nonluminous halos inside the
void form a web of tiny filaments. Thus, both the Local Group data and the
nearby voids indicate that isolated halos below 45 +/- 10 km/s must not host
galaxies and that small (few Mpc) voids are truly dark.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 10:56:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tikhonov",
"Anton V.",
""
],
[
"Klypin",
"Anatoly A.",
""
]
] |
0707.3525 | Lorenzo Iorio | Lorenzo Iorio | On the orbital and physical parameters of the HDE 226868/Cygnus X-1
binary system | Latex2e, 7 pages, 1 table, 4 figures. To appear in ApSS (Astrophysics
and Space Science) | Astrophys.SpaceSci.315:335-340,2008 | 10.1007/s10509-008-9839-y | null | gr-qc astro-ph | null | In this paper we explore the consequences of the recent determination of the
mass m=(8.7 +/- 0.8)M_Sun of Cygnus X-1, obtained from the Quasi-Periodic
Oscillation (QPO)-photon index correlation scaling, on the orbital and physical
properties of the binary system HDE 226868/Cygnus X-1. By using such a result
and the latest spectroscopic optical data of the HDE 226868 supergiant star we
get M=(24 +/- 5)M_Sun for its mass. It turns out that deviations from the third
Kepler law significant at more than 1-sigma level would occur if the
inclination i of the system's orbital plane to the plane of the sky falls
outside the range 41-56 deg: such deviations cannot be due to the first
post-Newtonian (1PN) correction to the orbital period because of its smallness;
interpreted in the framework of the Newtonian theory of gravitation as due to
the stellar quadrupole mass moment Q, they are unphysical because Q would take
unreasonably large values. By conservatively assuming that the third Kepler law
is an adequate model for the orbital period we obtain i=(48 +/- 7) deg which
yields for the relative semimajor axis a=(42 +/- 9)R_Sun. Our estimate for the
Roche's lobe of HDE 226868 is r_M = (21 +/- 6)R_Sun.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:00:19 GMT"
},
{
"version": "v2",
"created": "Mon, 26 May 2008 16:01:24 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Iorio",
"Lorenzo",
""
]
] |
0707.3526 | Nansen Petrosyan | Nansen Petrosyan | Cohomology of Split Group Extensions and Characteristic Classes | 13 pages | Journal of Algebra, Volume 321, Issue 10, 15 May 2009, Pages
2916-2925 | null | null | math.AT math.GR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | There are characteristic classes that are the obstructions to the vanishing
of the differentials in the Lyndon-Hochischild-Serre spectral sequence of an
extension of an integral lattice L by a group G. These characteristic classes
exist in a given page of the spectral sequence provided the differentials in
the previous pages are all zero. When L decomposes into a sum of G-sublattices,
we show that there are defining relations between the characteristic classes of
L and the characteristic classes of its summands.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:07:24 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Jun 2009 16:03:21 GMT"
}
] | 2009-06-18T00:00:00 | [
[
"Petrosyan",
"Nansen",
""
]
] |
0707.3527 | Mousumi Das | M. Das (RRI), S. S. McGaugh (UMD), N. Kantharia (NCRA), S. N. Vogel
(UMD) | Radio Observations of AGN in Low Surface Brightness Galaxies | To appear in proceedings IAU Symp 244, 'Dark Galaxies and Lost
Baryons', June 2007, 2 pages including 1 figure | null | 10.1017/S1743921307014238 | null | astro-ph | null | We present preliminary results of a study of the low frequency radio
continuum emission from the nuclei of Giant Low Surface Brightness (LSB)
galaxies. We have mapped the emission and searched for extended features such
as radio lobes/jets associated with AGN activity. LSB galaxies are poor in star
formation and generally less evolved compared to nearby bright spirals. This
paper presents low frequency observations of 3 galaxies; PGC 045080 at 1.4 GHz,
610 MHz, 325MHz, UGC 1922 at 610 MHz and UGC 6614 at 610 MHz. The observations
were done with the GMRT. Radio cores as well as extended structures were
detected and mapped in all three galaxies; the extended emission may be
assocated with jets/lobes associated with AGN activity. Our results indicate
that although these galaxies are optically dim, their nuclei can host AGN that
are bright in the radio domain.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:22:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Das",
"M.",
"",
"RRI"
],
[
"McGaugh",
"S. S.",
"",
"UMD"
],
[
"Kantharia",
"N.",
"",
"NCRA"
],
[
"Vogel",
"S. N.",
"",
"UMD"
]
] |
0707.3528 | Dieter H. Mayer | Akhtam Dzhalilov, Isabelle Liousse, Dieter Mayer | Singular measures of circle homeomorphisms with two break points | null | Discrete and continuous dynamical systems, 24, no. 2 (2009)
381-403 | null | null | math.DS math.PR | null | Let $T_{f}$ be a circle homeomorphism with two break points $a_{b},c_{b}$ and
irrational rotation number $\varrho_{f}$. Suppose that the derivative $Df$ of
its lift $f$ is absolutely continuous on every connected interval of the set
$S^{1}\backslash\{a_{b},c_{b}\}$, that $DlogDf \in L^{1}$ and the product of
the jump ratios of $ Df $ at the break points is nontrivial, i.e.
$\frac{Df_{-}(a_{b})}{Df_{+}(a_{b})}\frac{Df_{-}(c_{b})}{Df_{+}(c_{b})}\neq1$.
We prove that the unique $T_{f}$- invariant probability measure $\mu_{f}$ is
then singular with respect to Lebesgue measure $l$ on $S^{1}$.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:35:06 GMT"
}
] | 2010-11-22T00:00:00 | [
[
"Dzhalilov",
"Akhtam",
""
],
[
"Liousse",
"Isabelle",
""
],
[
"Mayer",
"Dieter",
""
]
] |
0707.3529 | Oleg Kargaltsev | G. G. Pavlov, O. Kargaltsev, and W. F. Brisken | Chandra Observation of PSR B1823-13 and its Pulsar Wind Nebula | 13 pages, 8 figures and 3 tables; submitted to ApJ | null | 10.1086/525842 | null | astro-ph | null | We report on an observation of the Vela-like pulsar B1823-13 and its
synchrotron nebula with Chandra.The pulsar's spectrum fits a power-law model
with a photon index Gamma_PSR=2.4 for the plausible hydrogen column density
n_H=10^{22} cm^{-2}, corresponding to the luminosity L_PSR=8*10^{31} ergs
s^{-1} in the 0.5-8 keV band, at a distance of 4 kpc. The pulsar radiation
likely includes magnetospheric and thermal components, but they cannot be
reliably separated because of the small number of counts detected and strong
interstellar absorption. The pulsar is surrounded by a compact, 25''x 10'',
pulsar wind nebula (PWN) elongated in the east-west direction, which includes a
brighter inner component, 7''x 3'', elongated in the northeast-southwest
direction. The slope of the compact PWN spectrum is Gamma_comp=1.3, and the
0.5-8 keV luminosity is L_comp~3*10^{32} ergs s^{-1}. The compact PWN is
surrounded by asymmetric diffuse emission (extended PWN) seen up to at least
2.4' south of the pulsar, with a softer spectrum (Gamma_ext=1.9), and the 0.5-8
keV luminosity L_ext~10^{33}-10^{34} ergs s^{-1}. We also measured the pulsar's
proper motion using archival VLA data: \mu_\alpha=23.0+/-2.5 mas yr^{-1},
\mu_\delta=-3.9+/-3.3 mas yr^{-1}, which corresponds to the transverse
velocity v_perp=440 km s^{-1}. The direction of the proper motion is
approximately parallel to the elongation of the compact PWN, but it is nearly
perpendicular to that of the extended PWN and to the direction towards the
center of the bright VHE gamma-ray source HESS J1825-137, which is likely
powered by PSR B1823-13.
| [
{
"version": "v1",
"created": "Tue, 24 Jul 2007 11:50:38 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Pavlov",
"G. G.",
""
],
[
"Kargaltsev",
"O.",
""
],
[
"Brisken",
"W. F.",
""
]
] |
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