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| versions
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0704.3101 | Seung-il Nam | Seung-il Nam, Ki-Seok Choi, Atsushi Hosaka, Hyun-Chul Kim | A new candidate for non-strangeness pentaquarks: N*(1675) | 5 pages, 8 figures, Talk given at Yukawa International Seminar (YKIS)
2006 "New frontiers in QCD", 20 Nov. ~ 8 Dec. 2006, Yukawa Institute for
Theoretical Physics (YITP), Kyoto, Japan | Prog.Theor.Phys.Suppl.168:97-100,2007 | 10.1143/PTPS.168.97 | PNU-NTG-04/2007, PNU-NuRI-04/2007 | hep-ph | null | We study a new nucleon resonance from eta photoproduction, which was observed
at sqrt{s}=1675 MeV with a narrow decay width (~10 MeV) by the Tohoku LNS group
as well as the GRAAL collaboration. Using an effective Lagrangian approach, we
compute differential cross sections for the eta photoproduction. In addition to
N*(1675,1/2+-,3/2+-), we employ six other nucleon resonances, i.e.
N*(1520,1535,1650,1675,1710,1720) and vector meson exchanges which are the most
relevant ones to this reaction process. As a result, we can reproduce the GRAAL
data qualitatively well and observe obvious isospin asymmetry between the
transition magnetic moments of N*(1675): mu_{gamma nn*} >> mu_{gamma pp*},
which indicates that the newly found nucleon resonance may be identified as a
non-strange pentaquark state.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 01:33:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nam",
"Seung-il",
""
],
[
"Choi",
"Ki-Seok",
""
],
[
"Hosaka",
"Atsushi",
""
],
[
"Kim",
"Hyun-Chul",
""
]
] |
0704.3102 | Hernando Quevedo | Hernando Quevedo | Geometrothermodynamics of black holes | Revised version, to be published in Gen.Rel.Grav.(Mashhoon's
Festschrift) | Gen.Rel.Grav.40:971-984,2008 | 10.1007/s10714-007-0586-0 | null | gr-qc | null | The thermodynamics of black holes is reformulated within the context of the
recently developed formalism of geometrothermodynamics. This reformulation is
shown to be invariant with respect to Legendre transformations, and to allow
several equivalent representations. Legendre invariance allows us to explain a
series of contradictory results known in the literature from the use of
Weinhold's and Ruppeiner's thermodynamic metrics for black holes. For the
Reissner-Nordstr\"om black hole the geometry of the space of equilibrium states
is curved, showing a non trivial thermodynamic interaction, and the curvature
contains information about critical points and phase transitions. On the
contrary, for the Kerr black hole the geometry is flat and does not explain its
phase transition structure.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 01:37:35 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 18:33:21 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Quevedo",
"Hernando",
""
]
] |
0704.3103 | Alexander O. Korotkevich | A.O. Korotkevich (1), A.C. Newell (2), and V.E. Zakharov (2,3,4,1)
((1) Landau Institute for Theoretical Physics RAS, (2) Department of
Mathematics, University of Arizona, Tucson, (3) Lebedev Physical Institute
RAS, (4) Waves and Solitons LLC, Phoenix) | Communication through plasma sheaths | 30 pages, 18 figures | A.O. Korotkevich, A.C. Newell, and V.E. Zakharov, Communication
through plasma sheaths, J. Appl. Phys., vol. 102, issue 8, p. 083305 (2007) | 10.1063/1.2794856 | null | physics.plasm-ph nlin.PS physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We wish to transmit messages to and from a hypersonic vehicle around which a
plasma sheath has formed. For long distance transmission, the signal carrying
these messages must be necessarily low frequency, typically 2 GHz, to which the
plasma sheath is opaque. The idea is to use the plasma properties to make the
plasma sheath appear transparent.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 01:50:02 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Dec 2010 14:53:39 GMT"
}
] | 2011-01-04T00:00:00 | [
[
"Korotkevich",
"A. O.",
""
],
[
"Newell",
"A. C.",
""
],
[
"Zakharov",
"V. E.",
""
]
] |
0704.3104 | Wako Aoki | Wako Aoki, Satoshi Honda, Kozo Sadakane, Nobuo Arimoto | The first determination of the actinide Th abundance for a red giant of
the Ursa Minor dwarf galaxy | 5 pages, 2 figures, 1 table, to appear in PASJ | null | 10.1093/pasj/59.3.L15 | null | astro-ph | null | The Thorium abundance for the red giant COS82 in the Ursa Minor dwarf
spheroidal galaxy is determined based on a high resolution spectrum. This is
the first detection of actinides in an extra Galactic object. A detailed
abundance pattern is determined for 12 other neutron-capture elements from the
atomic number 39 to 68. These elements are significantly over-abundant with
respect to other metals like Fe (> 1 dex) and their abundance pattern agrees
well with those of the r-process-enhanced, very metal-poor stars known in the
Galactic halo, while the metallicity of this object ([Fe/H] ~ -1.5) is much
higher than these field stars ([Fe/H] ~ -3.0). The results indicate that the
mechanism and the astrophysical site that are responsible for neutron-capture
elements in COS82 is similar to that for field r-process-enhanced stars, while
the condition of low mass star formation is quite different. An estimate of the
age of this object based on the Th abundance ratio is discussed.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 01:52:22 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Aoki",
"Wako",
""
],
[
"Honda",
"Satoshi",
""
],
[
"Sadakane",
"Kozo",
""
],
[
"Arimoto",
"Nobuo",
""
]
] |
0704.3105 | Xing-Hua Wu | Xin-Heng Guo and Xing-Hua Wu | Studying the scalar bound states of the $K\bar K$ system in the
Bethe-Salpeter formalism | 23 pages, LaTeX2e. Discussions on the legitimacy of the ladder
approximation and the instantaneous approximation are added. Recognized typos
have been corrected. Several references added | Phys.Rev.D76:056004,2007 | 10.1103/PhysRevD.76.056004 | null | hep-ph | null | We study the possible bound states of the $K\bar K$ system in the
Bethe-Salpeter formalism in the ladder and instantaneous approximations. We
find that the bound states exist. However, these bound states have very small
decay widths. Therefore, besides the possible $K\bar K$ component, there may be
some other structures in the observed $f_0(980)$ and $a_0(980)$ .
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 02:02:52 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Jul 2007 01:46:10 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Guo",
"Xin-Heng",
""
],
[
"Wu",
"Xing-Hua",
""
]
] |
0704.3106 | Keivan G. Stassun | Keivan G. Stassun, Robert D. Mathieu, Jeff A. Valenti | A Surprising Reversal of Temperatures in the Brown-Dwarf Eclipsing
Binary 2MASS J05352184-0546085 | 31 pages, 7 figures, accepted by ApJ | Astrophys.J.664:1154-1166,2007 | 10.1086/519231 | null | astro-ph | null | The newly discovered brown-dwarf eclipsing binary 2MASS J05352184-0546085
provides a unique laboratory for testing the predictions of theoretical models
of brown-dwarf formation and evolution. The finding that the lower-mass brown
dwarf in this system is hotter than its higher-mass companion represents a
challenge to brown-dwarf evolutionary models, none of which predict this
behavior. Here we present updated determinations of the basic physical
properties of 2M0535-05, bolstering the surprising reversal of temperatures
with mass in this system. We compare these measurements with widely used
brown-dwarf evolutionary tracks, and find that the temperature reversal can be
explained by some models if the components of 2M0535-05 are mildly non-coeval,
possibly consistent with dynamical simulations of brown-dwarf formation.
Alternatively, a strong magnetic field on the higher-mass brown dwarf might
explain its anomalously low surface temperature, consistent with emerging
evidence that convection is suppressed in magnetically active, low-mass stars.
Finally, we discuss future observational and theoretical work needed to further
characterize and understand this benchmark system.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 02:11:52 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Stassun",
"Keivan G.",
""
],
[
"Mathieu",
"Robert D.",
""
],
[
"Valenti",
"Jeff A.",
""
]
] |
0704.3107 | Guowu Meng | Guowu Meng | The Representation Aspect of the Generalized Hydrogen Atoms | 18 pages, simplified proof | Journal of Lie Theory 18 (2008), No. 3, 697-715 | null | null | math-ph math.MP | null | Let $D\ge 1$ be an integer. In the Enright-Howe-Wallach classification list
of the unitary highest weight modules of $\widetilde{\mr{Spin}}(2, D+1)$, the
(nontrivial) Wallach representations in Case II, Case III, and the mirror of
Case III are special in the sense that they are precisely the ones that can be
realized by the Hilbert space of bound states for a generalized hydrogen atom
in dimension D. It has been shown recently that each of these special Wallach
representations can be realized as the space of L^2-sections of a canonical
hermitian bundle over the punctured ${\bb R}^D$. Here a simple algebraic
characterization of these special Wallach representations is found.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:08:01 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 05:58:13 GMT"
},
{
"version": "v3",
"created": "Thu, 26 Apr 2007 13:13:41 GMT"
},
{
"version": "v4",
"created": "Tue, 17 Jul 2007 06:05:03 GMT"
},
{
"version": "v5",
"created": "Thu, 9 Aug 2007 02:58:10 GMT"
},
{
"version": "v6",
"created": "Sat, 29 Dec 2007 06:46:41 GMT"
}
] | 2008-11-29T00:00:00 | [
[
"Meng",
"Guowu",
""
]
] |
0704.3108 | Tim Bastian | T. S. Bastian | Synchrotron Radio Emission from a Fast Halo Coronal Mass Ejection | 19 pages, 3 figures | Astrophys.J.665:805-812,2007 | 10.1086/519246 | null | astro-ph | null | An interplanetary (IP) type-II-like radio burst is analyzed. It occurred on
2003 June 17-18 in association with a fast halo coronal mass ejection (CME), an
M6.8 soft-X-ray (SXR) flare, and produced a solar proton event. Unlike coronal
type II bursts and the ma jority of IP type II radio emissions, the IP
type-II-like event associated with the fast halo CME on June 17-18 varies
smoothly in time and frequency and has a frequency bandwidth that is several
times larger than is typical for coronal and IP type II emissions. Moreover,
the frequency change with time is inconsistent with that expected from plasma
radiation associated with a CME-driven shock. I suggest that this IP
type-II-like event, referred to here as an IP type II-S event, is not due to
plasma radiation but, rather, incoherent synchrotron radiation from
near-relativistic electrons entrained in the CME magnetic field, or in the
sheath region between the shock and the CME driver. This event may be an
example of a new and distinct class of interplanetary radio phenomenon.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 02:19:24 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Bastian",
"T. S.",
""
]
] |
0704.3109 | Youichi Shibukawa | Youichi Shibukawa | Dynamical Yang-Baxter Maps with an Invariance Condition | 27 pages | null | null | null | math.QA math-ph math.MP | null | By means of left quasigroups L=(L, .) and ternary systems, we construct
dynamical Yang-Baxter maps associated with L, L, and (.) satisfying an
invariance condition that the binary operation (.) of the left quasigroup L
defines. Conversely, this construction characterize such dynamical Yang-Baxter
maps. The unitary condition of the dynamical Yang-Baxter map is discussed.
Moreover, we establish a correspondence between two dynamical Yang-Baxter maps
constructed in this paper. This correspondence produces a version of the
vertex-IRF correspondence.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 02:55:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Shibukawa",
"Youichi",
""
]
] |
0704.3110 | Irene M. Gamba | Irene M. Gamba, Maria Pia Gualdani and Ping Zhang | On the blowing up of solutions to quantum hydrodynamic models on bounded
domains | 14 pages | null | null | null | math-ph math.AP math.MP | null | The blow-up in finite time for the solutions to the initial-boundary value
problem associated to the multi-dimensional quantum hydrodynamic model in a
bounded domain is proved. The model consists on conservation of mass equation
and a momentum balance equation equivalent to a compressible Euler equations
corrected by a dispersion term of the third order in the momentum balance. The
proof is based on a-priori estimates for the energy functional for a new
observable constructed with an auxiliary function, and it is shown that, under
suitable boundary conditions and assumptions on the initial data, the solution
blows up after a finite time.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 03:19:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gamba",
"Irene M.",
""
],
[
"Gualdani",
"Maria Pia",
""
],
[
"Zhang",
"Ping",
""
]
] |
0704.3111 | M Zahid Hasan | Y.W. Li, D. Qian, L. Wray, D. Hsieh, Y. Kaga, T. Sasagawa, H. Takagi,
R.S. Markiewicz, A. Bansil, H. Eisaki, S. Uchida, M.Z. Hasan | Anisotropic softening of collective charge modes in the vicinity of
critical doping in a doped Mott insulator | 5 pages + 5 Figures | Phys. Rev. B 78, 073104 (2008) | 10.1103/PhysRevB.78.073104 | null | cond-mat.str-el cond-mat.supr-con | null | Momentum resolved inelastic resonant x-ray scattering is used to map the
evolution of charge excitations over a large range of energies, momenta and
doping levels in the electron doped Mott insulator class
Nd$_{2-x}$Ce$_x$CuO$_4$. As the doping induced AFM-SC
(antiferromagnetic-superconducting) transition is approached, we observe an
anisotropic softening of collective charge modes over a large energy scale
along the Gamma to (\pi,\pi)-direction, whereas the modes exhibit broadening
($\sim$ 1 eV) with relatively little softening along Gamma to (\pi,0) with
respect to the parent Mott insulator (x=0). Our study indicates a systematic
collapse of the gap consistent with the scenario that the system dopes
uniformly with electrons even though the softening of the modes involves an
unusually large energy scale.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 03:20:53 GMT"
}
] | 2008-12-11T00:00:00 | [
[
"Li",
"Y. W.",
""
],
[
"Qian",
"D.",
""
],
[
"Wray",
"L.",
""
],
[
"Hsieh",
"D.",
""
],
[
"Kaga",
"Y.",
""
],
[
"Sasagawa",
"T.",
""
],
[
"Takagi",
"H.",
""
],
[
"Markiewicz",
"R. S.",
""
],
[
"Bansil",
"A.",
""
],
[
"Eisaki",
"H.",
""
],
[
"Uchida",
"S.",
""
],
[
"Hasan",
"M. Z.",
""
]
] |
0704.3112 | Mikko Karttunen | Emppu Salonen, Emma Terama, Ilpo Vattulainen, Mikko Karttunen | Enhanced dielectrophoresis of nanocolloids by dimer formation | null | null | 10.1209/0295-5075/78/48004 | null | cond-mat.soft | null | We investigate the dielectrophoretic motion of charge-neutral, polarizable
nanocolloids through molecular dynamics simulations. Comparison to analytical
results derived for continuum systems shows that the discrete charge
distributions on the nanocolloids have a significant impact on their coupling
to the external field. Aggregation of nanocolloids leads to enhanced
dielectrophoretic transport, provided that increase in the dipole moment upon
aggregation can overcome the related increase in friction. The dimer
orientation and the exact structure of the nanocolloid charge distribution are
shown to be important in the enhanced transport.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 03:36:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Salonen",
"Emppu",
""
],
[
"Terama",
"Emma",
""
],
[
"Vattulainen",
"Ilpo",
""
],
[
"Karttunen",
"Mikko",
""
]
] |
0704.3113 | Rafe Mazzeo | Rafe Mazzeo, Mariel Saez | Self similar expanding solutions of the planar network flow | 14 pages | null | null | null | math.DG math.AP | null | We prove the existence of self-similar expanding solutions of the curvature
flow on planar networks where the initial configuration is any number of
half-lines meeting at the origin. This generalizes recent work by Schn\"urer
and Schulze which treats the case of three half-lines. There are multiple
solutions, and these are parametrized by combinatorial objects, namely Steiner
trees with respect to a complete negatively curved metric on the unit ball
which span $k$ specified points on the boundary at infinity. We also provide a
sharp formulation of the regularity of these solutions at $t=0$.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 04:12:38 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mazzeo",
"Rafe",
""
],
[
"Saez",
"Mariel",
""
]
] |
0704.3114 | Rina Kanamoto | Rina Kanamoto, Lincoln D. Carr, Masahito Ueda | Topological Winding and Unwinding in Metastable Bose-Einstein
Condensates | 4 pages, 3 figures | Phys. Rev. Lett. 100, 060401 (2008) | 10.1103/PhysRevLett.100.060401 | null | cond-mat.other | null | Topological winding and unwinding in a quasi-one-dimensional metastable
Bose-Einstein condensate are shown to be manipulated by changing the strength
of interaction or the frequency of rotation. Exact diagonalization analysis
reveals that quasidegenerate states emerge spontaneously near the transition
point, allowing a smooth crossover between topologically distinct states. On a
mean-field level, the transition is accompanied by formation of grey solitons,
or density notches, which serve as an experimental signature of this
phenomenon.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 18:32:09 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Nov 2007 21:33:36 GMT"
},
{
"version": "v3",
"created": "Tue, 12 Feb 2008 19:38:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kanamoto",
"Rina",
""
],
[
"Carr",
"Lincoln D.",
""
],
[
"Ueda",
"Masahito",
""
]
] |
0704.3115 | Tim Oliver Wehling | T. O. Wehling, H. P. Dahal, A. I. Lichtenstein, A. V. Balatsky | Local impurity effects in superconducting graphene | 4 pages, 4 figures | Phys. Rev. B 78, 035414 (2008) | 10.1103/PhysRevB.78.035414 | null | cond-mat.mes-hall cond-mat.supr-con | null | We study the effect of impurities in superconducting graphene and discuss
their influence on the local electronic properties. In particular, we consider
the case of magnetic and non-magnetic impurities being either strongly
localized or acting as a potential averaged over one unit cell. The spin
dependent local density of states is calculated and possibilities for
visualizing impurities by means of scanning tunneling experiments is pointed
out. A possibility of identifying magnetic scatters even by non spin-polarized
scanning tunneling spectroscopy is explained.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 04:45:36 GMT"
}
] | 2008-09-17T00:00:00 | [
[
"Wehling",
"T. O.",
""
],
[
"Dahal",
"H. P.",
""
],
[
"Lichtenstein",
"A. I.",
""
],
[
"Balatsky",
"A. V.",
""
]
] |
0704.3116 | Pawel Blasiak | P. Blasiak (1), A. Horzela (1), K. A. Penson (2), A. I. Solomon (2),
G. H. E. Duchamp (3), ((1) Polish Academy of Sciences, Krakow, Poland, (2)
LPTMC, University of Paris VI, France, (3) Institut Galilee, University of
Paris, France) | Combinatorics and Boson normal ordering: A gentle introduction | 8 pages, 1 figure | Am. J. Phys. 75, 639-646 (2007) | 10.1119/1.2723799 | null | quant-ph math-ph math.CO math.MP | null | We discuss a general combinatorial framework for operator ordering problems
by applying it to the normal ordering of the powers and exponential of the
boson number operator. The solution of the problem is given in terms of Bell
and Stirling numbers enumerating partitions of a set. This framework reveals
several inherent relations between ordering problems and combinatorial objects,
and displays the analytical background to Wick's theorem. The methodology can
be straightforwardly generalized from the simple example given herein to a wide
class of operators.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 04:46:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Blasiak",
"P.",
""
],
[
"Horzela",
"A.",
""
],
[
"Penson",
"K. A.",
""
],
[
"Solomon",
"A. I.",
""
],
[
"Duchamp",
"G. H. E.",
""
]
] |
0704.3117 | Michael Bromley | M.W.J. Bromley, J. Mitroy, K. Varga | Positronic complexes with unnatural parity | 10 pages RevTeX, 6 figures, in press Phys.Rev.A | Phys.Rev.A 75 062505 (2007) | 10.1103/PhysRevA.75.062505 | CSRCR 2007-09 | physics.atom-ph physics.chem-ph | null | The structure of the unnatural parity states of PsH, LiPs, NaPs and KPs are
investigated with the configuration interaction and stochastic variational
methods. The binding energies (in hartree) are found to be 8.17x10-4,
4.42x10-4, 15.14x10-4 and 21.80x10-4 respectively. These states are constructed
by first coupling the two electrons into a configuration which is predominantly
3Pe, and then adding a p-wave positron. All the active particles are in states
in which the relative angular momentum between any pair of particles is at
least L = 1. The LiPs state is Borromean since there are no 3-body bound
subsystems (of the correct symmetry) of the (Li+, e-, e-, e+) particles that
make up the system. The dominant decay mode of these states will be radiative
decay into a configuration that autoionizes or undergoes positron annihilation.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 04:57:09 GMT"
}
] | 2007-07-29T00:00:00 | [
[
"Bromley",
"M. W. J.",
""
],
[
"Mitroy",
"J.",
""
],
[
"Varga",
"K.",
""
]
] |
0704.3118 | S. Ole Warnaar | S Ole Warnaar | Proof of the Flohr-Grabow-Koehn conjectures for characters of
logarithmic conformal field theory | 13 pages, 1 figure | J.Phys.A40:12243,2007 | 10.1088/1751-8113/40/40/015 | null | hep-th math-ph math.MP math.QA | null | In a recent paper Flohr, Grabow and Koehn conjectured that the characters of
the logarithmic conformal field theory c_{k,1}, of central charge
c=1-6(k-1)^2/k, admit fermionic representations labelled by the Lie algebra
D_k. In this note we provide a simple analytic proof of this conjecture.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 04:57:30 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Warnaar",
"S Ole",
""
]
] |
0704.3119 | Soumitra SenGupta | Saurya Das (U of Lethbridge), Anindya Dey (HRI, Allahabad), Soumitra
SenGupta (IACS, Kolkata) | Stability and hierarchy problems in string inspired braneworld scenarios | 5 Pages, Revtex. Minor changes. To appear in Europhysics Letters | Europhys.Lett.83:51002,2008 | 10.1209/0295-5075/83/51002 | null | hep-th gr-qc hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We generalise the RS braneworld model by taking into account a general
stringy bulk containing the scalar dilaton field and the two-form Kalb-Ramond
field, apart from gravity. Assuming small fluctuations around a RS background,
the back-reacted warp factor is obtained. It is shown that the fine tuning
problem in connection with the Higgs mass reappears in a new guise and the
effective modular potential fails to stabilise the braneworld.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 05:10:21 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Aug 2008 00:11:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Das",
"Saurya",
"",
"U of Lethbridge"
],
[
"Dey",
"Anindya",
"",
"HRI, Allahabad"
],
[
"SenGupta",
"Soumitra",
"",
"IACS, Kolkata"
]
] |
0704.3120 | Oliver Henkel | Oliver Henkel | Space Time Codes from Permutation Codes | null | Proc. IEEE GlobeCom, San Francisco, California, Nov. 2006 | null | null | cs.IT math.IT | null | A new class of space time codes with high performance is presented. The code
design utilizes tailor-made permutation codes, which are known to have large
minimal distances as spherical codes. A geometric connection between spherical
and space time codes has been used to translate them into the final space time
codes. Simulations demonstrate that the performance increases with the block
lengths, a result that has been conjectured already in previous work. Further,
the connection to permutation codes allows for moderate complex en-/decoding
algorithms.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 05:45:30 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Henkel",
"Oliver",
""
]
] |
0704.3121 | Hongsheng Zhang | Hongsheng Zhang, Zong-Hong Zhu and Lihua Yang | Hybrid Chaplygin gas and phantom divide crossing | 11 pages, 4 figures, V3: discussions on the perturbation growth
added, V4: minor corrections, to match the published version | Modern Physics Letters A, Vol. 24, No. 7 (2009) 541 | 10.1142/S0217732309027303 | BNU/0375-2007 | astro-ph gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Hybrid Chaplygin gas model is put forward, in which the gases play the role
of dark energy. For this model the coincidence problem is greatly alleviated.
The effective equation of state of the dark energy may cross the phantom divide
$w=-1$. Furthermore, the crossing behaviour is decoupled from any gravity
theories. In the present model, $w<-1$ is only a transient behaviour. There is
a de Sitter attractor in the future infinity. Hence, the big rip singularity,
which often afflicts the models with matter whose effective equation of state
less than -1, is naturally disappear. There exist stable scaling solutions,
both at the early universe and the late universe. We discuss the perturbation
growth of this model. We find that the index is consistent with observations.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:16:34 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 07:03:39 GMT"
},
{
"version": "v3",
"created": "Wed, 1 Apr 2009 06:29:10 GMT"
},
{
"version": "v4",
"created": "Wed, 17 Jun 2009 05:07:02 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Zhang",
"Hongsheng",
""
],
[
"Zhu",
"Zong-Hong",
""
],
[
"Yang",
"Lihua",
""
]
] |
0704.3122 | Jean Bertoin | Jean Bertoin (PMA, Dma) | Two-parameter Poisson-Dirichlet measures and reversible exchangeable
fragmentation-coalescence processes | null | null | null | null | math.PR | null | We show that for $0<\alpha<1$ and $\theta>-\alpha$, the Poisson-Dirichlet
distribution with parameter $(\alpha, \theta)$ is the unique reversible
distribution of a rather natural fragmentation-coalescence process. This
completes earlier results in the literature for certain split and merge
transformations and the parameter $\alpha =0$.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:22:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bertoin",
"Jean",
"",
"PMA, Dma"
]
] |
0704.3123 | Ivan Area | I. Area, M.K. Atakishiyeva, and J. Rodal | On factorization of $q$-difference equation for continuous
$q$-ultraspherical polynomials | null | null | null | null | math.CA math-ph math.MP | null | We prove that a customary Sturm-Liouville form of second-order $q$-difference
equation for the continuous $q$-ultraspherical polynomials $C_n(x;\beta| q)$ of
Rogers can be written in a factorized form in terms of some explicitly defined
$q$-difference operator ${\mathcal D}_x^{\beta, q}$. This reveals the fact that
the continuous $q$-ultraspherical polynomials $C_n(x;\beta| q)$ are actually
governed by the $q$-difference equation ${\mathcal D}_x^{\beta, q} C_n(x;\beta|
q)= (q^{-n/2}+\beta q^{n/2}) C_n(x;\beta| q)$, which can be regarded as a
square root of the equation, obtained from its original form.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:34:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Area",
"I.",
""
],
[
"Atakishiyeva",
"M. K.",
""
],
[
"Rodal",
"J.",
""
]
] |
0704.3124 | Massimiliano Morini | Filippo Cagnetti, Maria Giovanna Mora, Massimiliano Morini | A second order minimality condition for the Mumford-Shah functional | 30 pages | null | null | Preprint SISSA 82/2006/M | math.AP math.OC | null | A new necessary minimality condition for the Mumford-Shah functional is
derived by means of second order variations. It is expressed in terms of a sign
condition for a nonlocal quadratic form on $H^1_0(\Gamma)$, $\Gamma$ being a
submanifold of the regular part of the discontinuity set of the critical point.
Two equivalent formulations are provided: one in terms of the first eigenvalue
of a suitable compact operator, the other involving a sort of nonlocal capacity
of $\Gamma$. A sufficient condition for minimality is also deduced. Finally, an
explicit example is discussed, where a complete characterization of the domains
where the second variation is nonnegative can be given.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:39:26 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cagnetti",
"Filippo",
""
],
[
"Mora",
"Maria Giovanna",
""
],
[
"Morini",
"Massimiliano",
""
]
] |
0704.3125 | Takehito Yokoyama | T. Yokoyama and Y. Tanaka | Theory of the tunneling spectroscopy of ferromagnetic superconductors | 4 pages, 2 figures | Phys. Rev. B 75, 132503 (2007) | 10.1103/PhysRevB.75.132503 | null | cond-mat.supr-con | null | We study tunneling conductance in normal metal / insulator / ferromagnetic
superconductor junctions. The tunneling spectra show a clear difference between
spin-singlet s-wave pairing, spin-triplet opposite spin pairing and
spin-triplet equal spin pairing: These pairings exhibit, respectively, gap
struture, double peak structure and zero bias peak in the spectra. The obtained
result may serve as a tool for determining the pairing symmetry of
ferromagnetic superconductors.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:41:38 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Yokoyama",
"T.",
""
],
[
"Tanaka",
"Y.",
""
]
] |
0704.3126 | Takehito Yokoyama | T. Yokoyama, Y. Sawa, Y. Tanaka, A. A. Golubov, A. Maeda and A.
Fujimaki | A quantitative model for IcR product in d-wave Josephson junctions | 4 pages, 6 figures | Phys. Rev. B 76, 052508 (2007) | 10.1103/PhysRevB.76.052508 | null | cond-mat.supr-con | null | We study theoretically the Josephson effect in d-wave superconductor /
diffusive normal metal /insulator/ diffusive normal metal/ d-wave
superconductor (D/DN/I/DN/D) junctions. This model is aimed to describe
practical junctions in high-$T_C$ cuprate superconductors, in which the product
of the critical Josephson current ($I_C$) and the normal state resistance ($R$)
(the so-called $I_{\rm C}R$ product) is very small compared to the prediction
of the standard theory. We show that the $I_{\rm C}R$ product in D/DN/I/DN/D
junctions can be much smaller than that in d-wave superconductor / insulator /
d-wave superconductor junctions and formulate the conditions necessary to
achieve large $I_{\rm C}R$ product in D/DN/I/DN/D junctions. The proposed
theory describes the behavior of $I_{\rm C}R$ products quantitatively in
high-$T_{\rm C}$ cuprate junctions.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 06:49:33 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Yokoyama",
"T.",
""
],
[
"Sawa",
"Y.",
""
],
[
"Tanaka",
"Y.",
""
],
[
"Golubov",
"A. A.",
""
],
[
"Maeda",
"A.",
""
],
[
"Fujimaki",
"A.",
""
]
] |
0704.3127 | Alberto Elduque | Alberto Elduque and Oliver Villa | The existence of superinvolutions | 21 pages | null | null | null | math.RA | null | Superinvolutions on graded associative algebras constitute a source of Lie
and Jordan superalgebras. Graded versions of the classical Albert and
Albert-Riehm Theorems on the existence of superinvolutions are proven.
Surprisingly, the existence of superinvolutions of the first kind is a rare
phenomenon, as nontrivial central division superalgebras are never endowed with
this kind of superinvolutions.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:07:50 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Elduque",
"Alberto",
""
],
[
"Villa",
"Oliver",
""
]
] |
0704.3128 | Li-Xin Li | Li-Xin Li (MPA) | Variation of the Amati Relation with the Cosmological Redshift: a
Selection Effect or an Evolution Effect? | 5 pages, including 5 figures. MNRAS Letters accepted | Mon.Not.Roy.Astron.Soc.Lett.379:L55-L59,2007 | 10.1111/j.1745-3933.2007.00333.x | null | astro-ph | null | Because of the limit in the number of gamma-ray bursts (GRBs) with available
redshifts and spectra, all current investigations on the correlation among GRB
variables use burst samples with redshifts that span a very large range. The
evolution and selection effects have thus been ignored, which might have
important influence on the results. In this Letter, we divide the 48
long-duration GRBs in Amati (2006, 2007) into four groups with redshift from
low to high, each group contains 12 GRBs. Then we fit each group with the Amati
relation $\log E_\iso = a + b \log E_\p$, and check if the parameters $a$ and
$b$ evolve with the GRB redshift. We find that $a$ and $b$ vary with the mean
redshift of the GRBs in each group systematically and significantly.
Monte-Carlo simulations show that there is only $\sim 4$ percent of chance that
the variation is caused by the selection effect arising from the fluence limit.
Hence, our results may indicate that GRBs evolve strongly with the cosmological
redshift.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:25:53 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Li",
"Li-Xin",
"",
"MPA"
]
] |
0704.3129 | Vincent Sacksteder IV | Vincent E. Sacksteder IV | Sums over geometries and improvements on the mean field approximation | Accepted for publication in Physical Review D, probably in November
2007. At the reviewer's request, material was added which made the article
more assertive, confident, and clear. No changes in substance | Phys.Rev.D76:105032,2007 | 10.1103/PhysRevD.76.105032 | null | hep-th cond-mat.dis-nn cond-mat.stat-mech | null | The saddle points of a Lagrangian due to Efetov are analyzed. This Lagrangian
was originally proposed as a tool for calculating systematic corrections to the
Bethe approximation, a mean-field approximation which is important in
statistical mechanics, glasses, coding theory, and combinatorial optimization.
Detailed analysis shows that the trivial saddle point generates a sum over
geometries reminiscent of dynamically triangulated quantum gravity, which
suggests new possibilities to design sums over geometries for the specific
purpose of obtaining improved mean field approximations to $D$-dimensional
theories. In the case of the Efetov theory, the dominant geometries are locally
tree-like, and the sum over geometries diverges in a way that is similar to
quantum gravity's divergence when all topologies are included. Expertise from
the field of dynamically triangulated quantum gravity about sums over
geometries may be able to remedy these defects and fulfill the Efetov theory's
original promise. The other saddle points of the Efetov Lagrangian are also
analyzed; the Hessian at these points is nonnormal and pseudo-Hermitian, which
is unusual for bosonic theories. The standard formula for Gaussian integrals is
generalized to nonnormal kernels.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:26:27 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Nov 2007 12:58:54 GMT"
}
] | 2012-12-13T00:00:00 | [
[
"Sacksteder",
"Vincent E.",
"IV"
]
] |
0704.3130 | Luigi Martina | Luigi Martina, Giulio Soliani | Hartree-Fock Approximation and Entanglement | 20 pages, 10 figures | null | null | null | quant-ph | null | The relation between the correlation energy and the entanglement is
analytically constructed for the Moshinsky's model of two coupled harmonic
oscillators. It turns out that the two quantities are far to be proportional,
even at very small couplings. A comparison is made also with the 2-point Ising
model.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:37:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Martina",
"Luigi",
""
],
[
"Soliani",
"Giulio",
""
]
] |
0704.3131 | Jose M. Diego Rodriguez | J.M. Diego, D. Herranz | Observing high redshift galaxy clusters through lensing of the
Ostriker-Vishniac effect | Submiteed to MNRAS | null | 10.1111/j.1365-2966.2007.12593.x | null | astro-ph | null | In this paper we study the possibility of detecting lensing signals in
high-resolution and high-sensitivity CMB experiments. At scales below 1 arcmin,
the CMB background is dominated by the Sunyaev-Zel'dovich effect in clusters
and by Ostriker-Vishniac effect distortions elsewhere. Assuming the
Sunyaev-Zel'dovich component in clusters can be removed, we focus on the
Ostriker-Vishniac effect and study the possibility of its detection while
paying special attention to contaminants, such as instrumental noise and point
sources. After designing an optimal filter for this particular lensing signal
we explore the signal-to-noise ratio for different scenarios varying the
resolution of the experiment, its sensitivity, and the level of contamination
due to point sources. Our results show that the next generation of experiments
should be able to do new and exciting science through the lensing effect of the
Ostriker-Vishniac background.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:12:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Diego",
"J. M.",
""
],
[
"Herranz",
"D.",
""
]
] |
0704.3132 | Zhang Z.-H. | X.-H. Guo, Z.-H. Zhang | Direct CP violation in $\bar{B}^0 \to \rho^0(\omega)\rho^0(\omega) \to
\pi^+\pi^-\pi^+\pi^-$ | 26 pages,11figures | Phys.Rev.D75:074028,2007 | 10.1103/PhysRevD.75.074028 | null | hep-ph | null | We study the direct CP violation in $\bar{B}^0 \to
\rho^0(\omega)\rho^0(\omega) \to \pi^+\pi^-\pi^+\pi^-$ (with unpolarized
$\rho^0(\omega)$) via the $\rho-\omega$ mixing mechanism which causes a large
strong phase difference and consequently a large CP violating asymmetry when
the masses of the $\pi^+\pi^-$ pairs are in the vicinity of the $\omega$
resonance. Since there are two $\rho (\omega)$ mesons in the intermediate state
$\rho-\omega$ mixing contributes twice to the first order of isospin violation,
leading to an even larger CP violating asymmetry (could be 30% -- 50% larger)
than in the case where only one $\rho (\omega)$ meson is involved. The CP
violating asymmetry depends on the Cabibbo-Kobayashi-Maskawa (CKM) matrix
elements and the hadronic matrix elements. The factorization approach is
applied in the calculation of the hadronic matrix elements with the
nonfactorizable effects being included effectively in an effective parameter,
$N_c$. We give the constraint on the range of $N_c$ from the latest
experimental data for the branching ratios for $\bar{B}^0 \to\rho^0\rho^0$ and
$\bar{B}^0 \to\rho^+\rho^-$. We find that the CP violating asymmetry could be
very large (even more than 90% for some values of $N_c$). It is shown that the
sensitivity of the CP violating asymmetry to $N_c$ is large compared with its
smaller sensitivity to the CKM matrix elements. We also discuss the possibility
to remove the mod $(\pi)$ ambiguity in the determination of the CP violating
phase angle $\alpha$ through the measurement of the CP violating asymmetry in
the decay $\bar{B}^0\to \rho^0(\omega)\rho^0(\omega) \to \pi^+\pi^-\pi^+\pi^-$.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:42:57 GMT"
}
] | 2011-03-15T00:00:00 | [
[
"Guo",
"X. -H.",
""
],
[
"Zhang",
"Z. -H.",
""
]
] |
0704.3133 | James Stewart | The HERMES Collaboration: A. Airapetian, et al | Transverse Polarization of Lambda and Lambda-bar Hyperons in Quasireal
Photoproduction | null | Phys.Rev.D76:092008,2007 | 10.1103/PhysRevD.76.092008 | DESY 07-036 | hep-ex | null | The HERMES experiment has measured the transverse polarization of Lambda and
Lambda-bar hyperons produced inclusively in quasireal photoproduction at a
positron beam energy of 27.6 GeV. The transverse polarization of the Lambda
hyperon is found to be positive while the observed Lambda-bar polarization is
compatible with zero. The transverse polarization values averaged over the
kinematic acceptance of HERMES are 0.078 +/- 0.006(stat) +/- 0.012(syst) and
-0.025 +/- 0.015(stat) +/- 0.018(syst) for Lambda and Lambda-bar hyperons,
respectively. The dependences of Lambda and Lambda-bar polarizations on the
fraction $\zeta$ of the beam's light-cone momentum carried by the hyperon and
on the hyperon's transverse momentum $p_T$ were investigated. The measured
Lambda polarization rises linearly with $p_T$ and exhibits a different behavior
for low and high values of $\zeta$, which approximately correspond to the
backward and forward regions in the center-of-mass frame of the $\gamma^*N$
reaction.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:44:53 GMT"
}
] | 2012-08-03T00:00:00 | [
[
"The HERMES Collaboration",
"",
""
],
[
"Airapetian",
"A.",
""
]
] |
0704.3134 | Farook Rahaman | F. Rahaman, S.Mal and P. Ghosh | A study of global monopole in Lyra geometry | 6 pages, Published in Mod.Phys.Lett.A19:2785-2790,2004 | null | 10.1142/S0217732304010862 | null | gr-qc | null | A class of exact static solution around a global monopole resulting from the
breaking of a global S0(3) symmetry is obtained in the context of Lyra
geometry. Our solution is shown to possess an interesting feature like
wormholes space-time. It has been shown that the global monopole exerts no
gravitational force on surrounding non-relativistic matter.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:51:10 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Rahaman",
"F.",
""
],
[
"Mal",
"S.",
""
],
[
"Ghosh",
"P.",
""
]
] |
0704.3135 | Reza Rezaei | R. Rezaei, R. Schlichenmaier, W. Schmidt, and O. Steiner
(Kiepenheuer-Institut fuer Sonnenphysik, Freiburg, Germany) | Opposite magnetic polarity of two photospheric lines in single spectrum
of the quiet Sun | 4 pages, 5 figures, accepted in Astronomy & Astrophysics Letters | null | 10.1051/0004-6361:20077441 | null | astro-ph | null | We study the structure of the photospheric magnetic field of the quiet Sun by
investigating weak spectro-polarimetric signals. We took a sequence of Stokes
spectra of the Fe I 630.15 nm and 630.25 nm lines in a region of quiet Sun near
the disk center, using the POLIS spectro-polarimeter at the German VTT on
Tenerife. The line cores of these two lines form at different heights in the
atmosphere. The 3$\sigma$ noise level of the data is about 1.8 $\times 10^{-3}
I_{c}$. We present co-temporal and co-spatial Stokes-$V$ profiles of the Fe I
630 nm line pair, where the two lines show opposite polarities in a single
spectrum. We compute synthetic line profiles and reproduce these spectra with a
two-component model atmosphere: a non-magnetic component and a magnetic
component. The magnetic component consists of two magnetic layers with opposite
polarity: the upper one moves upwards while the lower one moves downward.
In-between, there is a region of enhanced temperature. The Stokes-$V$ line pair
of opposite polarity in a single spectrum can be understood as a magnetic
reconnection event in the solar photosphere. We demonstrate that such a
scenario is realistic, but the solution may not be unique.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:38:51 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 16:27:08 GMT"
},
{
"version": "v3",
"created": "Wed, 9 May 2007 08:26:15 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rezaei",
"R.",
"",
"Kiepenheuer-Institut fuer Sonnenphysik, Freiburg, Germany"
],
[
"Schlichenmaier",
"R.",
"",
"Kiepenheuer-Institut fuer Sonnenphysik, Freiburg, Germany"
],
[
"Schmidt",
"W.",
"",
"Kiepenheuer-Institut fuer Sonnenphysik, Freiburg, Germany"
],
[
"Steiner",
"O.",
"",
"Kiepenheuer-Institut fuer Sonnenphysik, Freiburg, Germany"
]
] |
0704.3136 | Hayk Sarkisyan A | E.M. Kazaryan, L.S. Petrosyan, H.A. Sarkisyan | Hidden Symmetry, Excitonic Transitions and Two-Dimensional Kane's
Exciton in the Quantum Well | 11 pages, grant number added | null | null | null | cond-mat.other cond-mat.mtrl-sci | null | In this article it is shown that, Sommerfeld's coefficients for excitonic
transitions in quantum wells are determined only with the principle quantum
number within the framework of two-dimensional Coulomb potential. This is a
consequence of hidden symmetry of two-dimensional Coulomb problem, conditioned
by the existence of two-dimensional analog of the Runge-Lentz vector. For the
narrow gap semiconductor quantum well with the non-parabolic dispersion law of
electron and hole in the two-band Kane model it is shown that two-dimensional
excitonic states are described in the frames of an analog of Klein-Gordon
equation with the two-dimensional Coulomb potential. The non-stability of the
ground state of the two-dimensional Kane's exciton is show.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:55:48 GMT"
},
{
"version": "v2",
"created": "Tue, 29 May 2007 10:56:24 GMT"
}
] | 2007-06-13T00:00:00 | [
[
"Kazaryan",
"E. M.",
""
],
[
"Petrosyan",
"L. S.",
""
],
[
"Sarkisyan",
"H. A.",
""
]
] |
0704.3137 | Brenton Hall | M. Volk, S. Whitlock, B. V. Hall, A. I. Sidorov | Scanning magnetoresistance microscopy of atom chips | 6 pages, 6 figures | null | 10.1063/1.2839015 | null | physics.atom-ph | null | Surface based geometries of microfabricated wires or patterned magnetic films
can be used to magnetically trap and manipulate ultracold neutral atoms or
Bose-Einstein condensates. We investigate the magnetic properties of such atom
chips using a scanning magnetoresistive (MR) microscope with high spatial
resolution and high field sensitivity. We show that MR sensors are ideally
suited to observe small variations of the magnetic field caused by
imperfections in the wires or magnetic materials which ultimately lead to
fragmentation of ultracold atom clouds. Measurements are also provided for the
magnetic field produced by a thin current-carrying wire with small geometric
modulations along the edge. Comparisons of our measurements with a full numeric
calculation of the current flow in the wire and the subsequent magnetic field
show excellent agreement. Our results highlight the use of scanning MR
microscopy as a convenient and powerful technique for precisely characterizing
the magnetic fields produced near the surface of atom chips.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 07:58:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Volk",
"M.",
""
],
[
"Whitlock",
"S.",
""
],
[
"Hall",
"B. V.",
""
],
[
"Sidorov",
"A. I.",
""
]
] |
0704.3138 | Branislav Brutovsky | Branislav Brutovsky, Denis Horvath and Vladimir Lisy | Inverse Geometric Approach to the Simulation of the Circular Growth. The
Case of Multicellular Tumor Spheroids | null | null | 10.1016/j.physa.2007.10.036 | null | q-bio.CB | null | We demonstrate the power of the genetic algorithms to construct the cellular
automata model simulating the growth of 2-dimensional close-to-circular
clusters revealing the desired properties, such as the growth rate and, at the
same time, the fractal behavior of their contours. The possible application of
the approach in the field of tumor modeling is outlined.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:55:40 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Jul 2007 11:05:50 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Brutovsky",
"Branislav",
""
],
[
"Horvath",
"Denis",
""
],
[
"Lisy",
"Vladimir",
""
]
] |
0704.3139 | Pietro Gambardella | G. Boero, S. Mouaziz, S. Rusponi, P. Bencok, F. Nolting, S. Stepanow,
and P. Gambardella | Element-resolved x-ray ferrimagnetic and ferromagnetic resonance
spectroscopy | 16 pages, 8 figures | New J. Phys. 10, 013011 (2008) | 10.1088/1367-2630/10/1/013011 | null | cond-mat.mtrl-sci | null | We report on the measurement of element-specific magnetic resonance spectra
at gigahertz frequencies using x-ray magnetic circular dichroism (XMCD). We
investigate the ferrimagnetic precession of Gd and Fe ions in Gd-substituted
Yttrium Iron Garnet, showing that the resonant field and linewidth of Gd
precisely coincide with Fe up to the nonlinear regime of parametric
excitations. The opposite sign of the Gd x-ray magnetic resonance signal with
respect to Fe is consistent with dynamic antiferromagnetic alignment of the two
ionic species. Further, we investigate a bilayer metal film,
Ni$_{80}$Fe$_{20}$(5 nm)/Ni(50 nm), where the coupled resonance modes of Ni and
Ni$_{80}$Fe$_{20}$ are separately resolved, revealing shifts in the resonance
fields of individual layers but no mutual driving effects. Energy-dependent
dynamic XMCD measurements are introduced, combining x-ray absorption and
magnetic resonance spectroscopies.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:08:50 GMT"
},
{
"version": "v2",
"created": "Tue, 22 Jan 2008 12:55:16 GMT"
}
] | 2008-01-22T00:00:00 | [
[
"Boero",
"G.",
""
],
[
"Mouaziz",
"S.",
""
],
[
"Rusponi",
"S.",
""
],
[
"Bencok",
"P.",
""
],
[
"Nolting",
"F.",
""
],
[
"Stepanow",
"S.",
""
],
[
"Gambardella",
"P.",
""
]
] |
0704.3140 | Farook Rahaman | Farook Rahaman | Non static cosmic strings in Lyra geometry | 8 pages, Published in Nuovo Cim.118B:99-105,2003 | null | null | null | gr-qc | null | The gravitational field of both local and global non static cosmic strings in
the context of Lyra geometry are investigated. Local strings are characterized
by having an energy momentum tensor whose only non null components are $T_{tt}
= T_{zz}$ . As linearized Einstein equations are formally analogous to the
Maxwell equations, the exterior solution does not depend on the radial
distribution of the source and hence a Dirac d function was used to approximate
the radial distribution of the energy momentum tensor for a local cosmic string
along the z-axis: $T_{ab} = \delta(x) \delta(y)diag (\sigma, 0, 0, \sigma) $,
$\sigma $being the energy density of the string [A.Vilenkin.
Phys.Rep.(1985)121,263]. For a global string, the energy momentum tensor
components are calculated from the action density for a complex scalar field y
along with a Maxican hat potential. The gravitational field of the global
string is shown to be attractive in nature.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:09:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Rahaman",
"Farook",
""
]
] |
0704.3141 | Evgueni Petrov | Evgueni Petrov | Algorithm for Evaluation of the Interval Power Function of Unconstrained
Arguments | 3 pages | null | null | null | cs.MS | null | We describe an algorithm for evaluation of the interval extension of the
power function of variables x and y given by the expression x^y. Our algorithm
reduces the general case to the case of non-negative bases.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:33:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Petrov",
"Evgueni",
""
]
] |
0704.3142 | Alastair Kay | Alastair Kay | A QMA-Complete Translationally Invariant Hamiltonian Problem and the
Complexity of Finding Ground State Energies in Physical Systems | 4 pages. v2: Significantly revised interpretation of results. v3:
updated references, added example class of Hamiltonians | Phys. Rev. A 76, 030307(R) (2007) | 10.1103/PhysRevA.76.030307 | null | quant-ph cond-mat.str-el | null | Here we present a problem related to the local Hamiltonian problem
(identifying whether the ground state energy falls within one of two ranges)
which is restricted to being translationally invariant. We prove that for
problems with a fixed local dimension and O(\log(N))-body local terms, or local
dimension N and 2-body terms, there are instances of the problem which are
QMA-complete. We discuss the implications for the computational complexity of
finding ground states of these systems, and hence for any classical
approximation techniques that one could apply including DMRG, Matrix Product
States and MERA. One important example is a 1D lattice of bosons with
nearest-neighbor hopping at constant filling fraction i.e. a generalization of
the Bose-Hubbard model.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:41:17 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Apr 2007 14:10:03 GMT"
},
{
"version": "v3",
"created": "Tue, 29 May 2007 08:28:12 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Kay",
"Alastair",
""
]
] |
0704.3143 | Cosima Schuster | Udo Schwingenschloegl and Cosima Schuster | Charge redistribution at YBa2Cu3O7-metal interfaces | 3 pages, 2 figures, submitted to Appl. Phys. Lett | Appl. Phys. Lett., 192502 (2007) | 10.1063/1.2737397 | null | cond-mat.supr-con | null | Charge redistribution at interfaces is crucial for electronic applications of
high-Tc superconductors, since the band structure is modified on a local scale.
We address the normal-state electronic structure of YBa2Cu3O7 (YBCO) at an
YBCO-metal contact by first principles calculations for prototypical interface
configurations. We derive quantitative results for the intrinsic doping of the
superconducting CuO2 planes due to the metal contact. Our findings can be
explained in terms of a band-bending mechanism, complemented by local screening
effects. We determine a net charge transfer of 0.09 to 0.13 electrons in favour
of the intraplane Cu sites, depending on the interface orientation.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:53:10 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Schwingenschloegl",
"Udo",
""
],
[
"Schuster",
"Cosima",
""
]
] |
0704.3144 | Yves Wiaux | Y. Wiaux, J. D. McEwen, P. Vielva | Complex data processing: fast wavelet analysis on the sphere | 20 pages, 5 figures, JFAA style, paper invited to J. Fourier Anal.
and Applic | J. Fourier Anal. and Applic. 13 (2007) 477 | 10.1007/s00041-006-6917-9 | null | astro-ph math-ph math.MP | null | In the general context of complex data processing, this paper reviews a
recent practical approach to the continuous wavelet formalism on the sphere.
This formalism notably yields a correspondence principle which relates wavelets
on the plane and on the sphere. Two fast algorithms are also presented for the
analysis of signals on the sphere with steerable wavelets.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 08:54:32 GMT"
}
] | 2007-08-14T00:00:00 | [
[
"Wiaux",
"Y.",
""
],
[
"McEwen",
"J. D.",
""
],
[
"Vielva",
"P.",
""
]
] |
0704.3145 | G\'abor Braun | Gabor Braun and Andras Nemethi | Surgery formula for Seiberg--Witten invariants of negative definite
plumbed 3-manifolds | 17 pages, 4 figures, accepted by Journal f\"ur die reine und
angewandte Mathematik. Minor improvements suggested by referee | null | null | null | math.GT math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive a cut-and-paste surgery formula of Seiberg--Witten invariants for
negative definite plumbed rational homology 3-spheres. It is similar to (and
motivated by) Okuma's recursion formula [arXiv:math.AG/0610464, 4.5] targeting
analytic invariants of splice quotient singularities. The two formulas combined
provide automatically a proof of the equivariant version
[arXiv:math.AG/0310084, 5.2(b)] of the `Seiberg--Witten invariant conjecture'
[arXiv:math.AG/0111298] for these singularities.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:30:17 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Nov 2008 13:29:10 GMT"
}
] | 2008-11-20T00:00:00 | [
[
"Braun",
"Gabor",
""
],
[
"Nemethi",
"Andras",
""
]
] |
0704.3146 | Thomas Schaepers | P. Lehnen, Th. Schapers, N. Kaluza, N. Thillosen, and H. Hardtdegen | Enhanced spin-orbit scattering length in narrow Al_xGa_{1-x}N/GaN wires | 6 pages, 5 figures | null | 10.1103/PhysRevB.76.205307 | null | cond-mat.mes-hall | null | The magnetotransport in a set of identical parallel AlGaN/GaN quantum wire
structures was investigated. The width of the wires was ranging between 1110 nm
and 340 nm. For all sets of wires clear Shubnikov--de Haas oscillations are
observed. We find that the electron concentration and mobility is approximately
the same for all wires, confirming that the electron gas in the AlGaN/GaN
heterostructure is not deteriorated by the fabrication procedure of the wire
structures. For the wider quantum wires the weak antilocalization effect is
clearly observed, indicating the presence of spin-orbit coupling. For narrow
quantum wires with an effective electrical width below 250 nm the weak
antilocalization effect is suppressed. By comparing the experimental data to a
theoretical model for quasi one-dimensional structures we come to the
conclusion that the spin-orbit scattering length is enhanced in narrow wires.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:31:59 GMT"
},
{
"version": "v2",
"created": "Sat, 28 Jul 2007 11:57:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lehnen",
"P.",
""
],
[
"Schapers",
"Th.",
""
],
[
"Kaluza",
"N.",
""
],
[
"Thillosen",
"N.",
""
],
[
"Hardtdegen",
"H.",
""
]
] |
0704.3147 | Boldizsar Kalmar | Boldizsar Kalmar | Fold cobordisms and stable homotopy groups | 10 pages | Stud. Scient. Math. Hung. 46 (2009), 437-447. | null | null | math.GT math.AT | null | We show that the cobordism groups of negative codimensional folds maps
contain direct sums of stable homotopy groups of Thom spaces of vector bundles
like the circle and the infinite dimensional projective space. We give
geometrical invariants which detect these direct summands.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:40:26 GMT"
}
] | 2009-10-23T00:00:00 | [
[
"Kalmar",
"Boldizsar",
""
]
] |
0704.3148 | Jose Luis Flores | V. Alana, J.L. Flores | The causal boundary of product spacetimes | 21 pages, 7 figures | Gen.Rel.Grav.39:1697-1718,2007 | 10.1007/s10714-007-0492-5 | null | gr-qc | null | The new formulation of the causal completion of spacetimes suggested in [1],
and modified later in [2], is tested by computing the causal boundary for
product spacetimes of a Lorentz interval and a Riemannian manifold. This is
particularized for two important families of spacetimes, conformal to the
previous ones: (standard) static spacetimes and Generalized Robertson-Walker
spacetimes. As consequence, it is shown that this new approach essentially
reproduces the structure of the conformal boundary for multiple classical
spacetimes: Reissner-Nordstrom (including Schwarzschild), Anti-de Sitter, Taub
and standard cosmological models as de Sitter and Einstein Universe.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:46:56 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 09:56:10 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Alana",
"V.",
""
],
[
"Flores",
"J. L.",
""
]
] |
0704.3149 | Pierre Lesaffre | P. Lesaffre, M. Gerin, P. Hennebelle | Effects of turbulent diffusion on the chemistry of diffuse clouds | 13 pages, 23 figures, A&A accepted | null | 10.1051/0004-6361:20066807 | null | astro-ph | null | Aims. We probe the effect of turbulent diffusion on the chemistry at the
interface between a cold neutral medium (CNM) cloudlet and the warm neutral
medium (WNM). Methods. We perform moving grid, multifluid, 1D, hydrodynamical
simulations with chemistry including thermal and chemical diffusion. The
diffusion coefficients are enhanced to account for turbulent diffusion. We
post-process the steady-states of our simulations with a crude model of
radiative transfer to compute line profiles. Results. Turbulent diffusion
spreads out the transition region between the CNM and the WNM. We find that the
CNM slightly expands and heats up: its CH and H$_2$ content decreases due to
the lower density. The change of physical conditions and diffusive transport
increase the H$^+$ content in the CNM which results in increased OH and H$_2$O.
Diffusion transports some CO out of the CNM. It also brings H$_2$ into contact
with the warm gas with enhanced production of CH$^+$, H$_3^+$, OH and H$_2$O at
the interface. O lines are sensitive to the spread of the thermal profile in
the intermediate region between the CNM and the WNM. Enhanced molecular content
at the interface of the cloud broadens the molecular line profiles and helps
exciting transitions of intermediate energy. The relative molecular yield are
found higher for bigger clouds. Conclusions. Turbulent diffusion can be the
source of additional molecular production and should be included in chemical
models of the interstellar medium (ISM). It also is a good candidate for the
interpretation of observational problems such as warm H$_2$, CH$^+$ formation
and presence of H$_3^+$.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:53:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lesaffre",
"P.",
""
],
[
"Gerin",
"M.",
""
],
[
"Hennebelle",
"P.",
""
]
] |
0704.3150 | I. S. Glass | I. S. Glass, F. van Leeuwen | Semi-Regular Variables in the Solar Neighbourhood | MNRAS (accepted) | Mon.Not.Roy.Astron.Soc.378:1543-1549,2007 | 10.1111/j.1365-2966.2007.11903.x | null | astro-ph | null | Period-luminosity sequences have been shown to exist among the Semi-Regular
Variables (SRVs) in the Magellanic Clouds (Wood et al, 1999), the Bulge of the
Milky Way galaxy (Glass & Schultheis, 2003) and elsewhere. Using modern period
and revised Hipparcos parallax data, this paper demonstrates that they also
appear among the M-giant SRVs of the Solar Neighbourhood. Their distribution in
the K, log P diagram resembles that of Bulge stars more closely than those in
the Magellanic Clouds. The prevalence of mass-loss among local M-type SRVs and
its dependence on period and spectral sub-type are also discussed. K -- [12], a
measure of circumstellar dust emission, increases clearly with V amplitude, M
giant sub-type and log P.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 09:57:42 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Glass",
"I. S.",
""
],
[
"van Leeuwen",
"F.",
""
]
] |
0704.3151 | Manuel Alonso-Moron | \'Alvaro Mart\'inez P\'erez and M. A. Mor\'on | Uniformly continuous maps between ends of R-trees | null | null | null | null | math.GT math.MG | null | There is a well-known correspondence between infinite trees and ultrametric
spaces which can be interpreted as an equivalence of categories and comes from
considering the end space of the tree.
In this equivalence, uniformly continuous maps between the end spaces are
translated to some classes of coarse maps (or even classes of metrically proper
lipschitz maps) between the trees.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:02:10 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 18:15:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Pérez",
"Álvaro Martínez",
""
],
[
"Morón",
"M. A.",
""
]
] |
0704.3152 | Fabio Briscese | F. Briscese, A. Marciano | Cosmological Casimir effect with maximum planckian momentum and
accelerating universe | 9 pages | null | null | null | gr-qc astro-ph hep-th | null | We develop here a mechanism that, without making use of a cosmological
constant, reproduces an accelerating universe. This is done by taking into
account Casimir vacuum energy density, assuming that the underlying theory
allows a maximum momentum, that turns out to be the leading contribution term
to Einstein equations in a large expanding FRW universe. As stated in numerous
quantum gravity studies, we postulate that maximum momentum is related to the
existence of the Planck length as a fundamental length. This insight, together
with the assumption of a Planck scale correction to the energy/momentum
dispersion-relation on a FRW background, is used here to calculate Casimir
vacuum energy. We show that, under these hypothesis, an accelerated universe
expansion is obtained. As last step we analyze the compatibility of the
resulting model with experimental data, writing down the equation of state for
Casimir energy and pressure and observing that this equation of state belongs
to a class of models that naturally fits cosmological observations. We
emphasize that our result relies, once a fundamental length is introduced in
Casimir effect, just on general arguments thus it is independent on an explicit
form of the energy-momentum dispersion relation.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:08:00 GMT"
},
{
"version": "v2",
"created": "Tue, 24 Apr 2007 23:20:13 GMT"
},
{
"version": "v3",
"created": "Sat, 5 May 2007 15:00:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Briscese",
"F.",
""
],
[
"Marciano",
"A.",
""
]
] |
0704.3153 | Zhi-Zhong Xing | Aik Hui Chan, Harald Fritzsch, Shu Luo, Zhi-zhong Xing | Deviations from Tri-bimaximal Neutrino Mixing in Type-II Seesaw and
Leptogenesis | RevTeX 14 pages, 2 figures. Title and authors changed, and
discussions on the minimal type-II seesaw and leptogenesis added. Accepted
for publication in Phys. Rev. D | Phys.Rev.D76:073009,2007 | 10.1103/PhysRevD.76.073009 | null | hep-ph | null | Current experimental data allow the zero value for one neutrino mass, either
m_1 = 0 or m_3 = 0. This observation implies that a realistic neutrino mass
texture can be established by starting from the limit (a) m_1 = m_2 = 0 and m_3
\neq 0 or (b) m_1 = m_2 \neq 0 and m_3 = 0. In both cases, we may introduce a
particular perturbation which ensures the resultant neutrino mixing matrix to
be the tri-bimaximal mixing pattern or its viable variations with all entries
being formed from small integers and their square roots. We find that it is
natural to incorporate this kind of neutrino mass matrix in the minimal Type-II
seesaw model with only one heavy right-handed Majorana neutrino N in addition
to the SU(2)_L Higgs triplet \Delta_L. We show that it is possible to account
for the cosmological baryon number asymmetry in the m_3 =0 case via thermal
leptogenesis, in which the one-loop vertex correction to N decays is mediated
by \Delta_L and the CP-violating asymmetry of N decays is attributed to the
electron flavor.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:08:25 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Sep 2007 10:28:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chan",
"Aik Hui",
""
],
[
"Fritzsch",
"Harald",
""
],
[
"Luo",
"Shu",
""
],
[
"Xing",
"Zhi-zhong",
""
]
] |
0704.3154 | Andrea Ciardi Dr | D.J. Ampleford (1), S.V. Lebedev (2), A. Ciardi (3), S.N. Bland (2),
S.C. Bott (2), G.N. Hall (2), N. Naz (2), C.A. Jennings (1), M. Sherlock (2),
J.P. Chittenden (2), J.B.A.Palmer (2), A. Frank (4), E. Blackman (4) ((1)
Sandia National Laboratories, USA (2) Imperial College, UK (3) Observatoire
de Paris, France (4) Department of Physics and Astronomy, and Laboratory for
Laser Energetics, University of Rochester, USA) | Supersonic radiatively cooled rotating flows and jets in the laboratory | Accepted for publication in Physical Review Letters (16 pages, 5
figures) | null | 10.1103/PhysRevLett.100.035001 | null | astro-ph | null | The first laboratory astrophysics experiments to produce a radiatively cooled
plasma jet with dynamically significant angular momentum are discussed. A new
configuration of wire array z-pinch, the twisted conical wire array, is used to
produce convergent plasma flows each rotating about the central axis. Collision
of the flows produces a standing shock and jet that each have supersonic
azimuthal velocities. By varying the twist angle of the array, the rotation
velocity of the system can be controlled, with jet rotation velocities reaching
~20% of the propagation velocity.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 18:04:15 GMT"
},
{
"version": "v2",
"created": "Wed, 2 Jan 2008 10:07:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ampleford",
"D. J.",
""
],
[
"Lebedev",
"S. V.",
""
],
[
"Ciardi",
"A.",
""
],
[
"Bland",
"S. N.",
""
],
[
"Bott",
"S. C.",
""
],
[
"Hall",
"G. N.",
""
],
[
"Naz",
"N.",
""
],
[
"Jennings",
"C. A.",
""
],
[
"Sherlock",
"M.",
""
],
[
"Chittenden",
"J. P.",
""
],
[
"Palmer",
"J. B. A.",
""
],
[
"Frank",
"A.",
""
],
[
"Blackman",
"E.",
""
]
] |
0704.3155 | Charalampos Skokos | Ch. Skokos, T.C. Bountis and Ch. Antonopoulos | Geometrical properties of local dynamics in Hamiltonian systems: the
Generalized Alignment Index (GALI) method | 45 pages, 10 figures, accepted for publication in Physica D | null | 10.1016/j.physd.2007.04.004 | null | nlin.CD math-ph math.DS math.MP math.SG physics.acc-ph physics.class-ph physics.comp-ph | null | We investigate the detailed dynamics of multidimensional Hamiltonian systems
by studying the evolution of volume elements formed by unit deviation vectors
about their orbits. The behavior of these volumes is strongly influenced by the
regular or chaotic nature of the motion, the number of deviation vectors, their
linear (in)dependence and the spectrum of Lyapunov exponents. The different
time evolution of these volumes can be used to identify rapidly and efficiently
the nature of the dynamics, leading to the introduction of quantities that
clearly distinguish between chaotic behavior and quasiperiodic motion on
$N$-dimensional tori. More specifically we introduce the Generalized Alignment
Index of order $k$ (GALI$_k$) as the volume of a generalized parallelepiped,
whose edges are $k$ initially linearly independent unit deviation vectors from
the studied orbit whose magnitude is normalized to unity at every time step.
The GALI$_k$ is a generalization of the Smaller Alignment Index (SALI)
(GALI$_2$ $\propto$ SALI). However, GALI$_k$ provides significantly more
detailed information on the local dynamics, allows for a faster and clearer
distinction between order and chaos than SALI and works even in cases where the
SALI method is inconclusive.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:53:04 GMT"
}
] | 2019-08-19T00:00:00 | [
[
"Skokos",
"Ch.",
""
],
[
"Bountis",
"T. C.",
""
],
[
"Antonopoulos",
"Ch.",
""
]
] |
0704.3156 | Alan Sokal | Thierry de la Rue, Roberto Fernandez, Alan D. Sokal | How to clean a dirty floor: Probabilistic potential theory and the
Dobrushin uniqueness theorem | LaTex2e, 80 pages including 4 figures | Markov Processes and Related Fields 14, 1--78 (2008) | null | null | math.PR math-ph math.MP | null | Motivated by the Dobrushin uniqueness theorem in statistical mechanics, we
consider the following situation: Let \alpha be a nonnegative matrix over a
finite or countably infinite index set X, and define the "cleaning operators"
\beta_h = I_{1-h} + I_h \alpha for h: X \to [0,1] (here I_f denotes the
diagonal matrix with entries f). We ask: For which "cleaning sequences" h_1,
h_2, ... do we have c \beta_{h_1} ... \beta_{h_n} \to 0 for a suitable class of
"dirt vectors" c? We show, under a modest condition on \alpha, that this occurs
whenever \sum_i h_i = \infty everywhere on X. More generally, we analyze the
cleaning of subsets \Lambda \subseteq X and the final distribution of dirt on
the complement of \Lambda. We show that when supp(h_i) \subseteq \Lambda with
\sum_i h_i = \infty everywhere on \Lambda, the operators \beta_{h_1} ...
\beta_{h_n} converge as n \to \infty to the "balayage operator" \Pi_\Lambda =
\sum_{k=0}^\infty (I_\Lambda \alpha)^k I_{\Lambda^c). These results are
obtained in two ways: by a fairly simple matrix formalism, and by a more
powerful tree formalism that corresponds to working with formal power series in
which the matrix elements of \alpha are treated as noncommuting indeterminates.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:43:28 GMT"
}
] | 2008-07-25T00:00:00 | [
[
"de la Rue",
"Thierry",
""
],
[
"Fernandez",
"Roberto",
""
],
[
"Sokal",
"Alan D.",
""
]
] |
0704.3157 | Giorgio Terracina | Giorgio Terracina, Nicola Leone, Vincenzino Lio, Claudio Panetta | Experimenting with recursive queries in database and logic programming
systems | To appear in Theory and Practice of Logic Programming (TPLP) | null | null | null | cs.AI cs.DB | null | This paper considers the problem of reasoning on massive amounts of (possibly
distributed) data. Presently, existing proposals show some limitations: {\em
(i)} the quantity of data that can be handled contemporarily is limited, due to
the fact that reasoning is generally carried out in main-memory; {\em (ii)} the
interaction with external (and independent) DBMSs is not trivial and, in
several cases, not allowed at all; {\em (iii)} the efficiency of present
implementations is still not sufficient for their utilization in complex
reasoning tasks involving massive amounts of data. This paper provides a
contribution in this setting; it presents a new system, called DLV$^{DB}$,
which aims to solve these problems. Moreover, the paper reports the results of
a thorough experimental analysis we have carried out for comparing our system
with several state-of-the-art systems (both logic and databases) on some
classical deductive problems; the other tested systems are: LDL++, XSB, Smodels
and three top-level commercial DBMSs. DLV$^{DB}$ significantly outperforms even
the commercial Database Systems on recursive queries. To appear in Theory and
Practice of Logic Programming (TPLP)
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:58:40 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Terracina",
"Giorgio",
""
],
[
"Leone",
"Nicola",
""
],
[
"Lio",
"Vincenzino",
""
],
[
"Panetta",
"Claudio",
""
]
] |
0704.3158 | Jason McEwen | J. D. McEwen, P. Vielva, Y. Wiaux, R. B. Barreiro, L. Cayon, M. P.
Hobson, A. N. Lasenby, E. Martinez-Gonzalez, J. L. Sanz | Cosmological applications of a wavelet analysis on the sphere | 17 pages, 8 figures; JFAA invited review, in press | J. Fourier Anal. and Appl. 13 (2007) 495-510 | 10.1007/s00041-006-6918-8 | null | astro-ph math-ph math.MP | null | The cosmic microwave background (CMB) is a relic radiation of the Big Bang
and as such it contains a wealth of cosmological information. Statistical
analyses of the CMB, in conjunction with other cosmological observables,
represent some of the most powerful techniques available to cosmologists for
placing strong constraints on the cosmological parameters that describe the
origin, content and evolution of the Universe. The last decade has witnessed
the introduction of wavelet analyses in cosmology and, in particular, their
application to the CMB. We review here spherical wavelet analyses of the CMB
that test the standard cosmological concordance model. The assumption that the
temperature anisotropies of the CMB are a realisation of a statistically
isotropic Gaussian random field on the sphere is questioned. Deviations from
both statistical isotropy and Gaussianity are detected in the reviewed works,
suggesting more exotic cosmological models may be required to explain our
Universe. We also review spherical wavelet analyses that independently provide
evidence for dark energy, an exotic component of our Universe of which we know
very little currently. The effectiveness of accounting correctly for the
geometry of the sphere in the wavelet analysis of full-sky CMB data is
demonstrated by the highly significant detections of physical processes and
effects that are made in these reviewed works.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:45:37 GMT"
}
] | 2007-08-17T00:00:00 | [
[
"McEwen",
"J. D.",
""
],
[
"Vielva",
"P.",
""
],
[
"Wiaux",
"Y.",
""
],
[
"Barreiro",
"R. B.",
""
],
[
"Cayon",
"L.",
""
],
[
"Hobson",
"M. P.",
""
],
[
"Lasenby",
"A. N.",
""
],
[
"Martinez-Gonzalez",
"E.",
""
],
[
"Sanz",
"J. L.",
""
]
] |
0704.3159 | Henny Lamers | Henny J.G.L.M. Lamers | Mass Loss and Evolution of Stars and Star Clusters: a Personal
Historical Perspective | submitted to: Mass Loss from Stars and the Evolution of Stellar
Clusters, ASP Conf. Series, Eds. A. de Koter, L. Smith, R. Waters | null | null | null | astro-ph | null | The development and progress of the studies of winds and mass loss from hot
stars, from about 1965 up to now, is discussed in a personal historical
perspective. The present state of knowledge about stellar winds, based on
papers presented at this workshop, is described. About ten years ago the
mechanisms of the winds were reasonably well understood, the mass loss rates
were known, and the predictions of stellar evolution theory with mass loss
agreed with observations. However, recent studies especially those based on
FUSE observations, have resulted in a significant reduction of the mass loss
rates, that disagrees with predictions from radiation driven wind models. The
situation is discussed and future studies that can clarify the situation are
suggested.
I also discuss what is known about the dissolution of star clusters in
different environments. The dissolution time can be derived from the mass and
age distributions of cluster samples. The resulting dissolution times of
clusters in the solar neighborhood (SN) and in interacting galaxies are shorter
than predicted by two-body relaxation of clusters in a tidal field. Encounters
with giant molecular clouds can explain the fate of clusters in the SN and are
the most likely cause of the short lifetime of clusters in interacting
galaxies.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 10:57:56 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lamers",
"Henny J. G. L. M.",
""
]
] |
0704.3160 | Davoud Kamani | Davoud Kamani | New Form of the T-Duality Due to the Stability of a Compact Dimension | 12 pages, Latex, no figure | Int. J. Theor. Phys. 48, 611-620 (2009) | 10.1007/s10773-008-9834-7 | null | hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study behaviors of a compact dimension and the $T$-duality, in the
presence of the wrapped closed bosonic strings. When the closed strings
interact and form another system of strings, the radius of compactification
increases. This modifies the $T$-duality, which we call it as $T$-duality-like.
Some effects of the $T$-duality-like will be studied.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:00:15 GMT"
},
{
"version": "v2",
"created": "Sun, 31 Aug 2008 08:28:02 GMT"
}
] | 2020-08-21T00:00:00 | [
[
"Kamani",
"Davoud",
""
]
] |
0704.3161 | Baruch Meerson | Rui Liu, Yinchang Li, Meiying Hou, Baruch Meerson | van der Waals-like phase separation instability of a driven granular gas
in three dimensions | 7 pages, 7 figures, to appear in Phys. Rev. E | Phys. Rev. E 75 , 061304 (2007) | null | null | cond-mat.soft nlin.PS physics.flu-dyn | null | We show that the van der Waals-like phase separation instability of a driven
granular gas at zero gravity, previously investigated in two-dimensional
settings, persists in three dimensions. We consider a monodisperse granular gas
driven by a thermal wall of a three-dimensional rectangular container at zero
gravity. The basic steady state of this system, as described by granular
hydrodynamic equations, involves a denser and colder layer of granulate located
at the wall opposite to the driving wall. When the inelastic energy loss is
sufficiently high, the driven granular gas exhibits, in some range of average
densities, negative compressibility in the directions parallel to the driving
wall. When the lateral dimensions of the container are sufficiently large, the
negative compressibility causes spontaneous symmetry breaking of the basic
steady state and a phase separation instability. Event-driven molecular
dynamics simulations confirm and complement our theoretical predictions.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:00:47 GMT"
}
] | 2015-12-07T00:00:00 | [
[
"Liu",
"Rui",
""
],
[
"Li",
"Yinchang",
""
],
[
"Hou",
"Meiying",
""
],
[
"Meerson",
"Baruch",
""
]
] |
0704.3162 | Urpin Vadim | V.Urpin | Neutrino transport and hydrodynamic stability of rotating proto-neutron
stars | 6 pages. Accepted for publication in A&A | null | 10.1051/0004-6361:20066258 | null | astro-ph | null | We consider stability of differentially rotating non-magnetic proto-neutron
stars. When neutrino transport is efficient, the star can be subject to a
diffusive instability that can occur even in the convectively stable region.
The instability arises on the time-scale comparable to the time-scale of
thermal diffusion. Hydrodynamic motions driven by the instability can lead to
anisotropy in the neutrino flux since the instability is suppressed near the
equator and rotation axis.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:09:01 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Urpin",
"V.",
""
]
] |
0704.3163 | Thomas Dedieu | Thomas Dedieu | Severi varieties and self rational maps of K3 surfaces | 20 pages | Internat. J. Math., 20(12): 1455-1477, 2009 | null | null | math.AG | null | Self-rational maps of generic algebraic K3 surfaces are conjectured to be
trivial. We relate this conjecture to a conjecture concerning the
irreducibility of the universal Severi varieties parametrizing nodal curves of
given genus and degree lying on some K3 surface. We also establish a number of
numerical constraints satisfied by such non trivial rational maps, that is of
topological degree >1.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:15:22 GMT"
}
] | 2010-09-20T00:00:00 | [
[
"Dedieu",
"Thomas",
""
]
] |
0704.3164 | George Savvidy K | Jessica K. Barrett and George Savvidy | A dual lagrangian for non-Abelian tensor gauge fields | 13 pages, LaTex file | Phys.Lett.B652:141-145,2007 | 10.1016/j.physletb.2007.07.009 | NRCPS-HE-54-07 and RH-02-2007 | hep-th | null | For non-Abelian tensor gauge fields of the lower rank we have found an
alternative expression for the field strength tensors, which transform
homogeneously with respect to the complementary gauge transformations and allow
us to construct the dual Lagrangian.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:17:37 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Barrett",
"Jessica K.",
""
],
[
"Savvidy",
"George",
""
]
] |
0704.3165 | Peter Blake | E. W. Hill, A. K. Geim, K. Novoselov, F. Schedin and P. Blake | Graphene Spin Valve Devices | 3 pages, 6 figures | IEEE Trans. Magn. 42, 2694-2696 (2006) | 10.1109/TMAG.2006.878852 | null | cond-mat.mes-hall | null | Graphene - a single atomic layer of graphite - is a recently-found
two-dimensional form of carbon, which exhibits high crystal quality and
ballistic electron transport at room temperature. Soft magnetic NiFe electrodes
have been used to inject polarized spins into graphene and a 10% change in
resistance has been observed as the electrodes switch from the parallel to the
antiparallel state. This coupled with the fact that a field effect electrode
can modulate the conductivity of these graphene films makes them exciting
potential candidates for spin electronic devices.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:21:34 GMT"
}
] | 2019-08-19T00:00:00 | [
[
"Hill",
"E. W.",
""
],
[
"Geim",
"A. K.",
""
],
[
"Novoselov",
"K.",
""
],
[
"Schedin",
"F.",
""
],
[
"Blake",
"P.",
""
]
] |
0704.3166 | Margarida Hernanz | M. Hernanz (IEEC/Csic) and G. Sala (MPE) | XMM-Newton observations of Nova Sgr 1998 | 18 pages, 3 figures. Accepted in Astrophysical Journal | Astrophys.J.664:467-473,2007 | 10.1086/518780 | null | astro-ph | null | We report on X-ray observations of Nova Sagittarius 1998 (V4633 Sgr),
performed with XMM-Newton at three different epochs, 934, 1083 and 1265 days
after discovery. The nova was detected with the EPIC cameras at all three
epochs, with emission spanning the whole energy range from 0.2 to 10 keV.
The X-ray spectra do not change significantly at the different epochs, and
are well fitted for the first and third observations with a multi-temperature
optically thin thermal plasma, while lower statistics in the second
observations lead to a poorer fit. The thermal plasma emission is most probably
originated in the shock heated ejecta, with chemical composition similar to
that of a CO nova. However, we can not completely rule out reestablished
accretion as the origin of the emission. We also obtain upper limits for the
temperature and luminosity of a potential white dwarf atmospheric component,
and conclude that hydrogen burning had already turned-off by the time of our
observations.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:23:32 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Hernanz",
"M.",
"",
"IEEC/Csic"
],
[
"Sala",
"G.",
"",
"MPE"
]
] |
0704.3167 | Pekko Mets\"a | V.V. Abaev, P. Mets\"a, and M.E. Sainio | The Goldberger-Miyazawa-Oehme sum rule revisited | 4 pages, 1 figure. v2: Revised the second last paragraph of 5th
section and clarified the electromagnetic corrections (Tromborg vs.
$\chi$PT). Also removed the KH80 slope from the fig. 1 | Eur.Phys.J.A32:321-325,2007 | 10.1140/epja/i2007-10377-6 | HIP-2007-16/TH | hep-ph | null | The Goldberger-Miyazawa-Oehme sum rule is used to extract the pion-nucleon
coupling constant from experimental $\pi$N information. Chiral perturbation
theory is exploited in relating the pionic hydrogen s-wave level shift and
width results to the appropriate scattering lengths. The deduced value for the
coupling is $f^2 = 0.075 \pm 0.002$, where the largest source of uncertainty is
the determination of the s-wave $\pi^- p$ scattering length from the atomic
level shift measurement.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:36:57 GMT"
},
{
"version": "v2",
"created": "Mon, 21 May 2007 11:44:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Abaev",
"V. V.",
""
],
[
"Metsä",
"P.",
""
],
[
"Sainio",
"M. E.",
""
]
] |
0704.3168 | Valerij Kozhevnikov | V. P. Kozhevnikov (Ural State University, Russia) | Detection of superhumps in the VY Scl-type nova-like variable KR Aur | 6 pages, 6 figures, will be published in MNRAS | Mon.Not.Roy.Astron.Soc.378:955-960,2007 | 10.1111/j.1365-2966.2007.11819.x | null | astro-ph | null | We report on detection of negative superhumps in KR Aur which is the
representative member of the VY Scl stars. The observations were obtained with
the multi-channel photometer during 107 h. The analysis of the data clearly
revealed brightness variations with a period of 3.771 +/- 0.005 h. This is 3.5
per cent less than the orbital period, suggesting it is a negative superhump.
Negative superhumps in VY Scl stars are widely spread. The discovery of
powerful soft X-rays from V751 Cyg demonstrates that VY Scl stars may contain
white dwarfs, at which nuclear burning of the accreted material occur. If this
suspicion is correct, we then can suppose that the powerful radiation emerging
from the white dwarf may cause the tilt of the accretion disk to the orbital
plane, and its retrograde precession may produce negative superhumps in VY Scl
stars.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:46:30 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Kozhevnikov",
"V. P.",
"",
"Ural State University, Russia"
]
] |
0704.3169 | Scott Wolpert | Kunio Obitsu and Scott A. Wolpert | Grafting hyperbolic metrics and Eisenstein series | Published in Mathematischen Annalen, 2008. The original publication
is available at http://www.springerlink.com | null | null | null | math.CV math.AG | null | The family hyperbolic metric for the plumbing variety $\{zw=t\}$ and the non
holomorphic Eisenstein series $E(\zeta;2)$ are combined to provide an explicit
expansion for the hyperbolic metrics for degenerating families of Riemann
surfaces. Applications include an asymptotic expansion for the Weil-Petersson
metric and a local form of symplectic reduction.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:51:33 GMT"
},
{
"version": "v2",
"created": "Sat, 2 Feb 2008 18:47:41 GMT"
}
] | 2008-02-04T00:00:00 | [
[
"Obitsu",
"Kunio",
""
],
[
"Wolpert",
"Scott A.",
""
]
] |
0704.3170 | Damian H. Zanette | Damian H. Zanette | Zipf's law and city sizes: A short tutorial review on multiplicative
processes in urban growth | To appear in Advances in Complex Systems | null | null | null | physics.soc-ph cond-mat.stat-mech physics.data-an | null | We address the role of multiplicative stochastic processes in modeling the
occurrence of power-law city size distributions. As an explanation of the
result of Zipf's rank analysis, Simon's model is presented in a mathematically
elementary way, with a thorough discussion of the involved hypotheses. Emphasis
is put on the flexibility of the model, as to its possible extensions and the
relaxation of some strong assumptions. We point out some open problems
regarding the prediction of the detailed shape of Zipf's rank plots, which may
be tackled by means of such extensions.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 11:54:52 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zanette",
"Damian H.",
""
]
] |
0704.3171 | Thomas Preibisch | Thomas Preibisch | The origin of X-ray emission from T Tauri stars | Review talk at the Conference "Coronae of Stars and Accretion Disks",
Bonn, Germany, December 2006. Conference proceedings to be published in
Memorie della Societa Astronomica Italiana | null | null | null | astro-ph | null | Several aspects concerning the origin of the very strong X-ray activity of T
Tauri Stars (TTS) are still not well understood. Important new insight came
recently from the Chandra Orion Ultradeep Project (COUP), a unique 10-day long
Chandra observation of the Orion Nebula Cluster, and the XMM-Newton Extended
Survey of the Taurus Molecular Cloud (XEST). Based mainly on the results of
these two large projects, I will discuss our current knowledge about the
location of the X-ray emitting structures in TTS, the nature of their coronal
magnetic fields, inferences for pre-main-sequence magnetic dynamos, and the
relation between accretion processes and X-ray emission.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:02:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Preibisch",
"Thomas",
""
]
] |
0704.3172 | Debaprasad Giri | Sanjay Kumar and Debaprasad Giri | Force induced conformational transition in a system of interacting stiff
polymer: Application to unfolding | RevTeX v4, 9 pages with 6 eps figures | Phys. Rev. E 72, 052901 (2005) | 10.1103/PhysRevE.72.052901 | BHU-PHY/CMPT/05-01 | cond-mat.soft cond-mat.stat-mech physics.bio-ph | null | We consider a stiff polymer chain in poor solvent and apply a force at one
end of the chain. We find that by varying the stiffness parameter, polymer
undergoes a transition from the globule state to the folded like state. The
conformation of folded state mimics the $\beta$-sheet as seen in titin
molecule. Using exact enumeration technique, we study the extension-force and
force-temperature diagrams of such a system. Force-temperature diagram shows
the re-entrance behaviour for flexible chain. However, for stiff chain this
re-entrance behaviour is absent and there is an enhancement in
$\theta$-temperature with the rise of stiffness. We further propose that the
internal information about the frozen structure of polymer can be read from the
distribution of end-to-end distance which shows saw-tooth like behaviour.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:14:46 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Kumar",
"Sanjay",
""
],
[
"Giri",
"Debaprasad",
""
]
] |
0704.3173 | Vyacheslav P. Spiridonov | Igor M. Loutsenko and Vyacheslav P. Spiridonov | A Critical Phenomenon in Solitonic Ising Chains | This is a contribution to the Vadim Kuznetsov Memorial Issue on
Integrable Systems and Related Topics, published in SIGMA (Symmetry,
Integrability and Geometry: Methods and Applications) at
http://www.emis.de/journals/SIGMA/ | SIGMA 3 (2007), 059, 11 pages | 10.3842/SIGMA.2007.059 | null | cond-mat.stat-mech math-ph math.MP nlin.SI | null | We discuss a phase transition of the second order taking place in non-local
1D Ising chains generated by specific infinite soliton solutions of the KdV and
BKP equations.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:17:31 GMT"
}
] | 2008-04-24T00:00:00 | [
[
"Loutsenko",
"Igor M.",
""
],
[
"Spiridonov",
"Vyacheslav P.",
""
]
] |
0704.3174 | Ma\'ira Aguiar | Ma\'ira Aguiar, Nico Stollenwerk | A new chaotic attractor in a basic multi-strain epidemiological model
with temporary cross-immunity | 16 pages, 15 figures | null | null | null | nlin.CD q-bio.PE | null | An epidemic multi-strain model with temporary cross-immunity shows chaos,
even in a previously unexpected parameter region. Especially dengue fever
models with strong enhanced infectivity on secondary infection have previously
shown deterministic chaos motivated by experimental findings of
antibody-dependent-enhancement (ADE). Including temporary cross-immunity in
such models, which is common knowledge among field researchers in dengue, we
find a deterministically chaotic attractor in the more realistic parameter
region of reduced infectivity on secondary infection (''inverse ADE'' parameter
region). This is realistic for dengue fever since on second infection people
are more likely to be hospitalized, hence do not contribute to the force of
infection as much as people with first infection.
Our finding has wider implications beyond dengue in any multi-strain
epidemiological systems with altered infectivity upon secondary infection,
since we can relax the condition of rather high infectivity on secondary
infection previously required for deterministic chaos. For dengue the finding
of wide ranges of chaotic attractors open new ways to analysis of existing data
sets.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:18:46 GMT"
}
] | 2007-06-25T00:00:00 | [
[
"Aguiar",
"Maíra",
""
],
[
"Stollenwerk",
"Nico",
""
]
] |
0704.3175 | Debaprasad Giri | Debaprasad Giri and Sanjay Kumar | Effects of Eye-phase in DNA unzipping | RevTeX v4, 9 pages with 7 eps figures | Phys. Rev. E 73, 050903(R) (2006) | 10.1103/PhysRevE.73.050903 | BHU-PHY/CMPT/05-03 | cond-mat.soft cond-mat.stat-mech physics.bio-ph | null | The onset of an "eye-phase" and its role during the DNA unzipping is studied
when a force is applied to the interior of the chain. The directionality of the
hydrogen bond introduced here shows oscillations in force-extension curve
similar to a "saw-tooth" kind of oscillations seen in the protein unfolding
experiments. The effects of intermediates (hairpins) and stacking energies on
the melting profile have also been discussed.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:20:47 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Giri",
"Debaprasad",
""
],
[
"Kumar",
"Sanjay",
""
]
] |
0704.3176 | Sebastian Fallert | S.V. Fallert, Y.M. Kim, C.J. Neugebauer, S.N. Taraskin | The contact process in disordered and periodic binary two-dimensional
lattices | submitted to Physical Review E | null | 10.1103/PhysRevE.78.041117 | null | cond-mat.stat-mech | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The critical behavior of the contact process in disordered and periodic
binary 2d-lattices is investigated numerically by means of Monte Carlo
simulations as well as via an analytical approximation and standard mean field
theory. Phase-separation lines calculated numerically are found to agree well
with analytical predictions around the homogeneous point. For the disordered
case, values of static scaling exponents obtained via quasi-stationary
simulations are found to change with disorder strength. In particular, the
finite-size scaling exponent of the density of infected sites approaches a
value consistent with the existence of an infinite-randomness fixed point as
conjectured before for the 2d disordered CP. At the same time, both dynamical
and static scaling exponents are found to coincide with the values established
for the homogeneous case thus confirming that the contact process in a
heterogeneous environment belongs to the directed percolation universality
class.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:24:20 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Jun 2008 21:21:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fallert",
"S. V.",
""
],
[
"Kim",
"Y. M.",
""
],
[
"Neugebauer",
"C. J.",
""
],
[
"Taraskin",
"S. N.",
""
]
] |
0704.3177 | Andreas Enge | Andreas Enge (INRIA Futurs) | Computing modular polynomials in quasi-linear time | null | Mathematics of Computation 78, 267 (2009) 1809-1824 | null | null | math.NT cs.CC | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse and compare the complexity of several algorithms for computing
modular polynomials. We show that an algorithm relying on floating point
evaluation of modular functions and on interpolation, which has received little
attention in the literature, has a complexity that is essentially (up to
logarithmic factors) linear in the size of the computed polynomials. In
particular, it obtains the classical modular polynomials $\Phi_\ell$ of prime
level $\ell$ in time O (\ell^3 \log^4 \ell \log \log \ell). Besides treating
modular polynomials for $\Gamma^0 (\ell)$, which are an important ingredient in
many algorithms dealing with isogenies of elliptic curves, the algorithm is
easily adapted to more general situations. Composite levels are handled just as
easily as prime levels, as well as polynomials between a modular function and
its transform of prime level, such as the Schl\"afli polynomials and their
generalisations. Our distributed implementation of the algorithm confirms the
theoretical analysis by computing modular equations of record level around
10000 in less than two weeks on ten processors.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:27:39 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Jul 2008 12:33:49 GMT"
}
] | 2009-05-08T00:00:00 | [
[
"Enge",
"Andreas",
"",
"INRIA Futurs"
]
] |
0704.3178 | Adriana Elizabeth Nuncio Quiroz | A.E. Nuncio Quiroz (on behalf of the ZEUS Collaboration) | Beauty production using D* + mu and mu+ mu- correlations at ZEUS | 4 pages, 3 tables, 1 figure | null | null | null | hep-ex | null | Events with observed D* and/or muons in the final state were used to indicate
the presence of beauty quark production and to study the correlations between
the particles coming from the same or different B-hadrons. The Next-to-Leading
Order (NLO) theoretical predictions for such processes were often available
only at parton level. A method to calculate visible level cross sections at
NLO, based on an interface of the FMNR program to PYTHIA 6.2, is applied. It
uses the NLO description at b-quark level provided by FMNR applying a
statistical reduction procedure (REDSTAT) that allows the link to PYTHIA, from
where the description of the B-hadron decay chain is obtained. Comparisons of
the data and NLO cross sections at visible and b-quark level were found to be
consistent and equivalent.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:38:20 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Quiroz",
"A. E. Nuncio",
"",
"on behalf of the ZEUS Collaboration"
]
] |
0704.3179 | Sabrina Maniscalco | S. Maniscalco, J. Piilo, and K.-A. Suominen | Measurement-induced manipulation of the quantum-classical border | 7 pages, 3 figures | null | null | null | quant-ph | null | We demonstrate the possibility of controlling the border between the quantum
and the classical world by performing nonselective measurements on quantum
systems. We consider a quantum harmonic oscillator initially prepared in a
Schroedinger cat state and interacting with its environment. We show that the
environment induced decoherence transforming the cat state into a statistical
mixture can be strongly inhibited by means of appropriate sequences of
measurements.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:31:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Maniscalco",
"S.",
""
],
[
"Piilo",
"J.",
""
],
[
"Suominen",
"K. -A.",
""
]
] |
0704.3180 | Rahul Basu | Rahul Basu (IMSc), Eric Laenen (NIKHEF), Anuradha Misra (Mumbai U.),
Patrick Motylinski (NIKHEF) | Soft-collinear effects in prompt photon production | 14 pages, 12 figures, added comment on fragmentation contribution and
one more reference. Version to appear in Phys. Rev. D | Phys.Rev.D76:014010,2007 | 10.1103/PhysRevD.76.014010 | NIKHEF/2007-008, ITP-UU-07/23, IMSc-2007/04/5 | hep-ph | null | We extend next-to-leading logarithmic threshold and joint resummation for
prompt photon production to include leading collinear effects. The impact of
these effects is assessed for both fixed-target and collider kinematics. We
find them in general to be small, but noticeable.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:38:45 GMT"
},
{
"version": "v2",
"created": "Fri, 15 Jun 2007 08:18:30 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Basu",
"Rahul",
"",
"IMSc"
],
[
"Laenen",
"Eric",
"",
"NIKHEF"
],
[
"Misra",
"Anuradha",
"",
"Mumbai U."
],
[
"Motylinski",
"Patrick",
"",
"NIKHEF"
]
] |
0704.3181 | Dmitri Diakonov | Dmitri Diakonov and Victor Petrov (St. Petersburg NPI) | Confining ensemble of dyons | 26 pp. Construction of general N-ality = k strings added. The title
changed | Phys.Rev.D76:056001,2007 | 10.1103/PhysRevD.76.056001 | null | hep-th hep-lat | null | We construct the integration measure over the moduli space of an arbitrary
number of N kinds of dyons of the pure SU(N) gauge theory at finite
temperatures. The ensemble of dyons governed by the measure is mathematically
described by a (supersymmetric) quantum field theory that is exactly solvable
and is remarkable for a number of striking features: 1) The free energy has the
minimum corresponding to the zero average Polyakov line, as expected in the
confining phase; 2)The correlation function of two Polyakov lines exhibits a
linear potential between static quarks in any N-ality non-zero representation,
with a calculable string tension roughly independent of temperature; 3) The
average spatial Wilson loop falls off exponentially with its area and the same
string tension; 4) At a critical temperature the ensemble of dyons rearranges
and de-confines; 5)The estimated ratio of the critical temperature to the
square root of the string tension is in excellent agreement with the lattice
data.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 18:08:12 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Jun 2007 14:45:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Diakonov",
"Dmitri",
"",
"St. Petersburg NPI"
],
[
"Petrov",
"Victor",
"",
"St. Petersburg NPI"
]
] |
0704.3182 | James P. Sethna | Christopher R. Myers and James. P. Sethna | Python for Education: Computational Methods for Nonlinear Systems | Submitted to special issue of CiSE | null | null | null | nlin.CD | null | We describe a novel, interdisciplinary, computational methods course that
uses Python and associated numerical and visualization libraries to enable
students to implement simulations for a number of different course modules.
Problems in complex networks, biomechanics, pattern formation, and gene
regulation are highlighted to illustrate the breadth and flexibility of
Python-powered computational environments.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 18:55:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Myers",
"Christopher R.",
""
],
[
"Sethna",
"James. P.",
""
]
] |
0704.3183 | Shingo Takeuchi | Naoyuki Kawahara (KEK), Jun Nishimura (KEK, SOKENDAI), Shingo Takeuchi
(SOKENDAI) | Exact fuzzy sphere thermodynamics in matrix quantum mechanics | 22 pages, 14 figures, (v2) some typos corrected | JHEP 0705:091,2007 | 10.1088/1126-6708/2007/05/091 | KEK-TH-1145 | hep-th astro-ph hep-lat | null | We study thermodynamical properties of a fuzzy sphere in matrix quantum
mechanics of the BFSS type including the Chern-Simons term. Various quantities
are calculated to all orders in perturbation theory exploiting the one-loop
saturation of the effective action in the large-N limit. The fuzzy sphere
becomes unstable at sufficiently strong coupling, and the critical point is
obtained explicitly as a function of the temperature. The whole phase diagram
is investigated by Monte Carlo simulation. Above the critical point, we obtain
perfect agreement with the all order results. In the region below the critical
point, which is not accessible by perturbation theory, we observe the Hagedorn
transition. In the high temperature limit our model is equivalent to a totally
reduced model, and the relationship to previously known results is clarified.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:13:59 GMT"
},
{
"version": "v2",
"created": "Thu, 31 May 2007 12:36:57 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kawahara",
"Naoyuki",
"",
"KEK"
],
[
"Nishimura",
"Jun",
"",
"KEK, SOKENDAI"
],
[
"Takeuchi",
"Shingo",
"",
"SOKENDAI"
]
] |
0704.3184 | Alexander Burinskii | Alexander Burinskii | Kerr-Schild Photonlike Metric Solutions | 6 p, Revtex4 | null | null | null | gr-qc hep-th | null | The charged and spinning lightlike solutions are obtained in the Kerr-Schild
formalism. In particular, one of them may be considered as an ultrarelativistic
boost of the Kerr-Newman solution along the direction of angular momentum. The
Kerr singular ring disappears, however, there remains a finite parameter $a$
which determines spin by the Kerr relation $J=ma$. By $J=\hbar$, the parameter
$a$ is de Broglie wavelength of the corresponding photon. Electromagnetic field
is aligned to the Kerr null congruence. Some of the presented solutions contain
singular beam pulse (pp-strings) like the considered recently `gyratons'.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:01:59 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 11:18:01 GMT"
},
{
"version": "v3",
"created": "Thu, 20 Mar 2008 13:18:54 GMT"
}
] | 2008-03-20T00:00:00 | [
[
"Burinskii",
"Alexander",
""
]
] |
0704.3185 | Jonas Persson | Jonas R. Persson | Relativistic self-consistent-field calculations of the hyperfine
structure in the 4d-shell ions | 11 pages, 3 tables | null | null | null | physics.atom-ph | null | Relativistic self-consistent-field calculations of the radial hyperfine
integrals have been performed in the 4d-shell element ions. The comparison with
available experimental results gives an estimate of configuration interaction
effects in the hyperfine interaction in these ions. The results can also be
used to derive nuclear moments from laserspectroscopic measurements of
radioactive isotopes.
PACS Numbers: 31.15.Ne, 31.30.Gs, 32.10.Fn
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:02:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Persson",
"Jonas R.",
""
]
] |
0704.3186 | Silvio Paolo Sorella | S.P. Sorella | On the dynamical mass generation in confining Yang-Mills theories | 11 pages | AnnalsPhys.321:1747-1761,2006 | 10.1016/j.aop.2006.02.014 | null | hep-th | null | The dynamical mass generation for gluons is discussed in Euclidean Yang-Mills
theories supplemented with a renormalizable mass term. The mass parameter is
not free, being determined in a self-consistent way through a gap equation
which obeys the renormalization group. The example of the Landau gauge is
worked out explicitly at one loop order. A few remarks on the issue of the
unitarity are provided.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 17:57:42 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Sorella",
"S. P.",
""
]
] |
0704.3187 | Laura Magrini | Laura Magrini, Edvige Corbelli, Daniele Galli | The building up of the disk galaxy M33 and the evolution of the
metallicity gradient | 16 pages, 11 figures, A&A accepted | null | 10.1051/0004-6361:20077215 | null | astro-ph | null | The evolution of radial gradients of metallicity in disk galaxies and its
relation with the disk formation are not well understood. Theoretical models of
galactic chemical evolution make contrasting predictions about the time
evolution of metallicity gradients. To test chemical evolution models and trace
the star formation and accretion history of low luminosity disk galaxies we
focus on the Local Group galaxy M33. We analyze O/H and S/H abundances in
planetary nebulae, H{\sc ii} regions, and young stars, together with known
[Fe/H] abundances in the old stellar population of M33. With a theoretical
model, we follow the time evolution of gas (diffuse and condensed in clouds),
stars, and chemical abundances in the disk of M33, assuming that the galaxy is
accreting gas from an external reservoir. Our model is able to reproduce the
available observational constraints on the distribution of gas and stars in M33
and to predict the time evolution of several chemical abundances. In
particular, we find that a model characterized by a continuous infall of gas on
the disk, at a rate of $\dot M_{\rm inf}\approx 1$ $M_\odot$ yr$^{-1}$, almost
constant with time, can also account for the relatively high rate of star
formation and for the shallow chemical gradients. Supported by a large sample
of high resolution observations for this nearby galaxy, we conclude that the
metallicity in the disk of M33 has increased with time at all radii, with a
continuous flattening of the gradient over the last $\sim 8$ Gyr.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:40:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Magrini",
"Laura",
""
],
[
"Corbelli",
"Edvige",
""
],
[
"Galli",
"Daniele",
""
]
] |
0704.3188 | Sebastien Maret | Sebastien Maret and Edwin A. Bergin | The Ionization Fraction of Barnard 68: Implications for Star and Planet
Formation | To appear in the Astrophysical Journal | Astrophys.J.664:956-963,2007 | 10.1086/519152 | null | astro-ph | null | We present a detailed study of the ionization fraction of the Barnard 68
pre-stellar core, using millimeter H13CO+ and DCO+ lines observations. These
observations are compared to the predictions of a radiative transfer model
coupled to a chemical network that includes depletion on grains and gas phase
deuterium fractionation. Together with previous observations and modelling of
CO and isotopologues, our H13CO+ and DCO+ observations and modelling allow to
place constraints on the metal abundance and the cosmic ionization rate. The
H13CO+ emission is well reproduced for metals abundances lower than 3e-9 and a
standard cosmic ray ionization rate. However, the observations are also
consistent with a complete depletion of metals, i.e. with cosmic rays as the
only source of ionization at visual extinctions greater than a few Av . The
DCO+ emission is found to be dependent of the ortho to para H2 ratio, and
indicates a ratio of ~1e-2. The derived ionization fraction is about 5e-9 with
respect to H nuclei, which is about an order of magnitude lower than the one
observed in the L1544 core. The corresponding ambipolar diffusion timescale is
found to be an order of magnitude larger than the free fall timescale at the
center of the core. The inferred metal abundance suggests that magnetically
inactive regions (dead zones) are present in protostellar disks.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:07:51 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Maret",
"Sebastien",
""
],
[
"Bergin",
"Edwin A.",
""
]
] |
0704.3189 | V. Gogohia | V. Gogokhia | II. The mass gap and solution of the quark confinement problem in QCD | No tables and figures, 15 pages | null | null | null | hep-ph hep-th | null | We have investigated a closed system of equations for the quark propagator,
obtained earlier within our general approach to QCD at low energies. It implies
quark confinement (the quark propagator has no pole, indeed), as well as the
dynamical breakdown of chiral symmetry (a chiral symmetry preserving solution
is forbidded). This system can be solved exactly in the chiral limit. We have
established the space of the smooth test functions (consisting of the Green's
functions for the quark propagator and the corresponding quark-gluon vertex) in
which our generalized function (the confining gluon propagator) becomes a
continuous linear functional. It is a linear topological space $K(c)$ of the
infinitely differentiable functions (with respect to the dimensionless momentum
variable $x$), having compact support in the region $x \leq c$. We develop an
analytical formalism, the so-called chiral perturbtion theory at the
fundamental quark level, which allows one to find explicit solution for the
quark propagator in powers of the light quark masses. We also develop an
analytical formalism, which allows one to find the solution for the quark
propagator in the inverse powers of the heavy quark masses. It justifies the
use for the heavy quark propagator its free counterpart up to terms of the
order $1/m_Q^3$, where $m_Q$ is the heavy quark mass. So this solution
automatically possesses the heavy quark spin-flavor symmetry.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:16:13 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gogokhia",
"V.",
""
]
] |
0704.3190 | Karine Sartelet | Karine Sartelet (CEREA), Hiroshi Hayami (CRIEPI), Bruno Sportisse
(CEREA) | MICS Asia Phase II - Sensitivity to the aerosol module | Atmospheric Environment (2007) in press | null | 10.1016/j.atmosenv.2007.03.005 | null | physics.ao-ph | null | In the framework of the model inter-comparison study - Asia Phase II (MICS2),
where eight models are compared over East Asia, this paper studies the
influence of different parameterizations used in the aerosol module on the
aerosol concentrations of sulfate and nitrate in PM10. An intracomparison of
aerosol concentrations is done for March 2001 using different configurations of
the aerosol module of one of the model used for the intercomparison. Single
modifications of a reference setup for model configurations are performed and
compared to a reference case. These modifications concern the size
distribution, i.e. the number of sections, and physical processes, i.e.
coagulation, condensation/evaporation, cloud chemistry, heterogeneous reactions
and sea-salt emissions. Comparing monthly averaged concentrations at different
stations, the importance of each parameterization is first assessed. It is
found that sulfate concentrations are little sensitive to sea-salt emissions
and to whether condensation is computed dynamically or by assuming
thermodynamic equilibrium. Nitrate concentrations are little sensitive to cloud
chemistry. However, a very high sensitivity to heterogeneous reactions is
observed. Thereafter, the variability of the aerosol concentrations to the use
of different chemistry transport models (CTMs) and the variability to the use
of different parameterizations in the aerosol module are compared. For sulfate,
the variability to the use of different parameterizations in the aerosol module
is lower than the variability to the use of different CTMs. However, for
nitrate, for monthly averaged concentrations averaged over four stations, these
two variabilities have the same order of magnitude.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:16:16 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sartelet",
"Karine",
"",
"CEREA"
],
[
"Hayami",
"Hiroshi",
"",
"CRIEPI"
],
[
"Sportisse",
"Bruno",
"",
"CEREA"
]
] |
0704.3191 | Teresa Mineo | T.Mineo, V.Mangano, S.Covino, G.Cusumano, V.La Parola, E.Troja,
P.Roming, D.N.Burrows, S.Campana, M.Capalbi, G.Chincarini, N.Gehrels,
P.Giommi, J.E.Hill, F.Marshall, A.Moretti, P.O'Brien, M.Page, M.Perri,
P.Romano, B.Sbarufatti, G.Sato, G.Tagliaferri | GRB 050410 and GRB 050412: are they really dark GRBs? | 6 figures, 9 pages, accepted for publication in A&A | null | 10.1051/0004-6361:20066594 | null | astro-ph | null | We present a detailed analysis of the prompt and afterglow emission of GRB
050410 and GRB 050412 detected by Swift for which no optical counterpart was
observed. The 15-150 keV energy distribution of the GRB 050410 prompt emission
shows a peak energy at 53 keV. The XRT light curve of this GRB decays as a
power law with a slope of alpha=1.06+/-0.04. The spectrum is well reproduced by
an absorbed power law with a spectral index Gamma_x=2.4+/-0.4 and a low energy
absorption N_H=4(+3;-2)x10^21 cm^(-2) which is higher than the Galactic value.
The 15-150 keV prompt emission in GRB 050412 is modelled with a hard
(Gamma=0.7+/-0.2) power law. The XRT light curve follows a broken power law
with the first slope alpha_1=0.7+/-0.4, the break time T_break=254(-41;+79) s
and the second slope alpha_2=2.8(-0.8;+0.5). The spectrum is fitted by a power
law with spectral index Gamma_x=1.3+/-0.2 which is absorbed at low energies by
the Galactic column. The GRB 050410 afterglow reveals the expected
characteristics of the third component of the canonical Swift light curve.
Conversely, a complex phenomenology was detected in the GRB 050412 because of
the presence of the very early break. The light curve in this case can be
interpreted as being the last peak of the prompt emission. The two bursts
present tight upper limits for the optical emission, however, neither of them
can be clearly classified as dark. For GRB 050410, the suppression of the
optical afterglow could be attributed to a low density interstellar medium
surrounding the burst. For GRB 050412, the evaluation of the darkness is more
difficult due to the ambiguity in the extrapolation of the X-ray afterglow
light curve.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:21:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mineo",
"T.",
""
],
[
"Mangano",
"V.",
""
],
[
"Covino",
"S.",
""
],
[
"Cusumano",
"G.",
""
],
[
"La Parola",
"V.",
""
],
[
"Troja",
"E.",
""
],
[
"Roming",
"P.",
""
],
[
"Burrows",
"D. N.",
""
],
[
"Campana",
"S.",
""
],
[
"Capalbi",
"M.",
""
],
[
"Chincarini",
"G.",
""
],
[
"Gehrels",
"N.",
""
],
[
"Giommi",
"P.",
""
],
[
"Hill",
"J. E.",
""
],
[
"Marshall",
"F.",
""
],
[
"Moretti",
"A.",
""
],
[
"O'Brien",
"P.",
""
],
[
"Page",
"M.",
""
],
[
"Perri",
"M.",
""
],
[
"Romano",
"P.",
""
],
[
"Sbarufatti",
"B.",
""
],
[
"Sato",
"G.",
""
],
[
"Tagliaferri",
"G.",
""
]
] |
0704.3192 | Katia Biazzo Dr | K. Biazzo (1,2), L. Pasquini (2), L. Girardi (3), A. Frasca (1), L. da
Silva (4), J. Setiawan (5), E. Marilli (1), A. P. Hatzes (6), S. Catalano
(1), ((1) INAF-OACt, (2) ESO-Garching, (3) INAF-OAPd, (4) ON/MCT, (5)
MPIA-Heidelberg, (6) TLS) | Deriving temperature, mass and age of evolved stars from high-resolution
spectra. Application to field stars and the open cluster IC 4651 | 11 pages, 9 figures, version accepted for publication in A&A. Major
changes: revised paper, new discussion of results, references added, one
additional figure | null | 10.1051/0004-6361:20077374 | null | astro-ph | null | We test our capability of deriving stellar physical parameters of giant stars
by analysing a sample of field stars and the well studied open cluster IC 4651
with different spectroscopic methods. The use of a technique based on
line-depth ratios (LDRs) allows us to determine with high precision the
effective temperature of the stars and to compare the results with those
obtained with a classical LTE abundance analysis. (i) For the field stars we
find that the temperatures derived by means of the LDR method are in excellent
agreement with those found by the spectral synthesis. This result is extremely
encouraging because it shows that spectra can be used to firmly derive
population characteristics (e.g., mass and age) of the observed stars. (ii) For
the IC 4651 stars we use the determined effective temperature to derive the
following results. a) The reddening E(B-V) of the cluster is 0.12+/-0.02,
largely independent of the color-temperature calibration used. b) The age of
the cluster is 1.2+/-0.2 Gyr. c) The typical mass of the analysed giant stars
is 2.0+/-0.2M_sun. Moreover, we find a systematic difference of about 0.2 dex
in log g between spectroscopic and evolutionary values. We conclude that, in
spite of known limitations, a classical spectroscopic analysis of giant stars
may indeed result in very reliable stellar parameters. We caution that the
quality of the agreement, on the other hand, depends on the details of the
adopted spectroscopic analysis.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:22:42 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Sep 2007 08:37:24 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Biazzo",
"K.",
""
],
[
"Pasquini",
"L.",
""
],
[
"Girardi",
"L.",
""
],
[
"Frasca",
"A.",
""
],
[
"da Silva",
"L.",
""
],
[
"Setiawan",
"J.",
""
],
[
"Marilli",
"E.",
""
],
[
"Hatzes",
"A. P.",
""
],
[
"Catalano",
"S.",
""
]
] |
0704.3193 | Elsa Henriques S | Elsa S. Henriques, Andrey V. Solov'yov | A Rational Method for Probing Macromolecules Dissociation: The
Antibody-Hapten System | 22 pages, 10 figures | null | 10.1140/epjd/e2008-00009-3 | null | physics.bio-ph physics.chem-ph | null | The unbinding process of a protein-ligand complex of major biological
interest was investigated by means of a computational approach at atomistic
classical mechanical level. An energy minimisation-based technique was used to
determine the dissociation paths of the system by probing only a relevant set
of generalized coordinates. The complex problem was reduced to a
low-dimensional scanning along a selected distance between the protein and the
ligand. Orientational coordinates of the escaping fragment (the ligand) were
also assessed in order to further characterise the unbinding. Solvent effects
were accounted for by means of the Poisson--Boltzmann continuum model. The
corresponding dissociation time was derived from the calculated barrier height,
in compliance with the experimentally reported Arrhenius-like behaviour. The
computed results are in good agreement with the available experimental data.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 12:47:34 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Henriques",
"Elsa S.",
""
],
[
"Solov'yov",
"Andrey V.",
""
]
] |
0704.3194 | Gilles Carron | Gilles Carron (LMJL) | L^2 harmonics forms on non compact manifolds | null | null | null | null | math.DG | null | The source of these notes is a series of lectures given at the CIMPA's summer
school "Recent Topics in Geometric Analysis".
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:32:34 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Carron",
"Gilles",
"",
"LMJL"
]
] |
0704.3195 | Andreas Ringwald | Andreas Ringwald (DESY) | Particle Interpretations of the PVLAS Data | 20 pages, 18 figures, pdproc.sty; talk presented at the XII
International Workshop on ``Neutrino Telescopes'', March 6-9, 2007, Venice,
Italy | null | null | DESY 07-054 | hep-ph | null | Recently the PVLAS collaboration reported the observation of a rotation of
linearly polarized laser light induced by a transverse magnetic field -- a
signal being unexpected within standard QED. In this review, we emphasize two
mechanisms which have been proposed to explain this result: production of a
single light neutral spin-zero particle or pair production of light minicharged
particles. We discuss a class of models, involving, in addition to our familiar
``visible'' photon, further light ``hidden paraphotons'', which mix
kinematically with the visible one, and further light paracharged particles. In
these models, very strong astrophysical and cosmological bounds on the weakly
interacting light particles mentioned above can be evaded. In the upcoming
year, a number of decisive laboratory based tests of the particle
interpretation of the PVLAS anomaly will be done. More generally, such
experiments, exploiting high fluxes of low-energy photons and/or large
electromagnetic fields, will dig into previously unconstrained parameter space
of the above mentioned models.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:55:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ringwald",
"Andreas",
"",
"DESY"
]
] |
0704.3196 | Hasan Karabulut | Hasan Karabulut | Distributed Gaussian polynomials as q-oscillator eigenfunctions | null | Journal of Mathematical Physics 47, 013508 (2006) | 10.1063/1.2161022 | null | math-ph math.MP | null | Karabulut and Sibert (\textit{J. Math. Phys}. \textbf{38} (9), 4815 (1997))
have constructed an orthogonal set of functions from linear combinations of
equally spaced Gaussians. In this paper we show that they are actually
eigenfunctions of a q-oscillator in coordinate representation. We also
reinterpret the coordinate representation example of q-oscillator given by
Macfarlane as the functions orthogonal with respect to an unusual inner product
definition. It is shown that the eigenfunctions in both q-oscillator examples
are infinitely degenerate.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 13:57:06 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Karabulut",
"Hasan",
""
]
] |
0704.3197 | Reinhard Klette | Fajie Li and Reinhard Klette | Euclidean Shortest Paths in Simple Cube Curves at a Glance | 8 pages | null | null | CITR-TR-198 | cs.CG cs.DM | null | This paper reports about the development of two provably correct approximate
algorithms which calculate the Euclidean shortest path (ESP) within a given
cube-curve with arbitrary accuracy, defined by $\epsilon >0$, and in time
complexity $\kappa(\epsilon) \cdot {\cal O}(n)$, where $\kappa(\epsilon)$ is
the length difference between the path used for initialization and the
minimum-length path, divided by $\epsilon$. A run-time diagram also illustrates
this linear-time behavior of the implemented ESP algorithm.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 03:54:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Li",
"Fajie",
""
],
[
"Klette",
"Reinhard",
""
]
] |
0704.3198 | Jong E Han | J. E. Han, and R. J. Heary | Imaginary-time formulation of steady-state nonequilibrium: application
to strongly correlated transport | 5 pages 3 figures | Phys Rev Lett 99, 236808 (2007) | 10.1103/PhysRevLett.99.236808 | null | cond-mat.str-el cond-mat.mes-hall | null | We extend the imaginary-time formulation of the equilibrium quantum many-body
theory to steady-state nonequilibrium with an application to strongly
correlated transport. By introducing Matsubara voltage, we keep the finite
chemical potential shifts in the Fermi-Dirac function, in agreement with the
Keldysh formulation. The formulation is applied to strongly correlated
transport in the Kondo regime using the quantum Monte Carlo method.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:10:30 GMT"
},
{
"version": "v2",
"created": "Sat, 6 Oct 2007 21:51:42 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Han",
"J. E.",
""
],
[
"Heary",
"R. J.",
""
]
] |
0704.3199 | Enrico Paolini | E. Paolini, M. Fossorier, M. Chiani | Generalized Stability Condition for Generalized and Doubly-Generalized
LDPC Codes | 5 pages, 2 figures, to appear in Proc. of IEEE ISIT 2007 | null | 10.1109/ISIT.2007.4557440 | null | cs.IT math.IT | null | In this paper, the stability condition for low-density parity-check (LDPC)
codes on the binary erasure channel (BEC) is extended to generalized LDPC
(GLDPC) codes and doublygeneralized LDPC (D-GLDPC) codes. It is proved that, in
both cases, the stability condition only involves the component codes with
minimum distance 2. The stability condition for GLDPC codes is always expressed
as an upper bound to the decoding threshold. This is not possible for D-GLDPC
codes, unless all the generalized variable nodes have minimum distance at least
3. Furthermore, a condition called derivative matching is defined in the paper.
This condition is sufficient for a GLDPC or DGLDPC code to achieve the
stability condition with equality. If this condition is satisfied, the
threshold of D-GLDPC codes (whose generalized variable nodes have all minimum
distance at least 3) and GLDPC codes can be expressed in closed form.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:11:58 GMT"
}
] | 2016-11-15T00:00:00 | [
[
"Paolini",
"E.",
""
],
[
"Fossorier",
"M.",
""
],
[
"Chiani",
"M.",
""
]
] |
0704.3200 | Samvel Ter-Antonyan | A. P. Garyaka, R. M. Martirosov, S. V. Ter-Antonyan, N. Nikolskaya, Y.
A. Gallant, L. Jones and J. Procureur | Rigidity-dependent cosmic ray energy spectra in the knee region obtained
with the GAMMA experiment | 28 pages, 18 figures, accepted for publication in Astroparticle
Physics | Astropart.Phys.28:169-181,2007 | 10.1016/j.astropartphys.2007.04.004 | null | astro-ph | null | On the basis of the extensive air shower (EAS) data obtained by the GAMMA
experiment, the energy spectra and elemental composition of the primary cosmic
rays are derived in the 1-100 PeV energy range. The reconstruction of the
primary energy spectra is carried out using an EAS inverse approach in the
framework of the SIBYLL2.1 and QGSJET01 interaction models and the hypothesis
of power-law primary energy spectra with rigidity-dependent knees. The energy
spectra of primary H, He, O-like and Fe-like nuclei obtained with the SIBYLL
interaction model agree with corresponding extrapolations of the balloon and
satellite data to ~1 PeV energies. The energy spectra obtained from the QGSJET
model show a predominantly proton composition in the knee region. The
rigidity-dependent knee feature of the primary energy spectra for each
interaction model is displayed at the following rigidities: ~2.5+/-0.2 PV
(SIBYLL) and ~3.1-4.2 PV (QGSJET). All the results presented are derived taking
into account the detector response, the reconstruction uncertainties of the EAS
parameters, and fluctuations in the EAS development.
| [
{
"version": "v1",
"created": "Tue, 24 Apr 2007 14:19:31 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Garyaka",
"A. P.",
""
],
[
"Martirosov",
"R. M.",
""
],
[
"Ter-Antonyan",
"S. V.",
""
],
[
"Nikolskaya",
"N.",
""
],
[
"Gallant",
"Y. A.",
""
],
[
"Jones",
"L.",
""
],
[
"Procureur",
"J.",
""
]
] |
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