Context. Material processed by the CNO cycle in stellar interiors is enriched in 17O. When mixing processes from the stellar surface reach these layers, as occurs when stars become red giants and undergo the first dredge up, the abundance of 17O increases. Such an occurrence explains the drop of the 16O/17O observed in RGB stars with mass larger than ~ 1.5M⊙. As a consequence, the interstellar medium is continuously polluted by the wind of evolved stars enriched in 17O.
Aims. Recently, the Laboratory for Underground Nuclear Astrophysics (LUNA) collaboration released an improved rate of the 17O(p, α)14N reaction. In this paper we discuss the impact that the revised rate has on the 16O/17O ratio at the stellar surface and on 17O stellar yields.
Methods. We computed stellar models of initial mass between 1 and 20 M⊙ and compared the results obtained by adopting the revised rate of the 17O(p, α)14N to those obtained using previous rates.
Results. The post-first dredge up 16O/17O ratios are about 20% larger than previously obtained. Negligible variations are found in the case of the second and the third dredge up. In spite of the larger 17O(p, α)14N rate, we confirm previous claims that an extra-mixing process on the red giant branch, commonly invoked to explain the low carbon isotopic ratio observed in bright low-mass giant stars, marginally affects the 16O/17O ratio. Possible effects on AGB extra-mixing episodes are also discussed. As a whole, a substantial reduction of 17O stellar yields is found. In particular, the net yield of stars with mass ranging between 2 and 20 M⊙ is 15 to 40% smaller than previously estimated.
Conclusions. The revision of the 17O(p, α)14N rate has a major impact on the interpretation of the 16O/17O observed in evolved giants, in stardust grains and on the 17O stellar yields.
The two lighter oxygen isotopes participate in the NO section of the CNO cycle. When CNO reaches an equilibrium, as occurs in the H-burning shell of a giant star or in the central region of main-sequence stars, the 16O/17O ratio is simply given by the inverse ratio of the respective proton-capture reaction rates, (1)In practice, since the three reaction rates only depend on temperature, this isotopic ratio traces the temperature profile within the H-burning zone. Variations of the 16O/17O isotopic ratio appear at the surface when the ashes of the H burning are mixed with the stellar surface as a result of, for instance, convective instabilities affecting the stellar envelope in red giant (RGB) and asymptotic giant (AGB) stars. This isotopic ratio can be measured from the IR spectra of giant stars. In early studies, the CO vibration-rotation, 4.6 μm fundamental or 2.3 μm first overtone bands were commonly used (Harris et al. 1988; Smith & Lambert 1990). With the advent of IR spectrographs characterized by high dispersion and high signal-to-noise ratios, more lines in the near-IR spectrum can be exploited to derive the CNO isotopic composition of giant stars (García-Hernández et al. 2010; Abia et al. 2012; Lebzelter et al. 2015; Hinkle et al. 2016). These measurements allow us to probe the depth attained by the mixing episodes that are responsible for the chemical variations observed at the stellar surface. We recall that in addition to convection, other processes may induce or contribute to deep mixing episodes, such as rotation, magnetic buoyancy, gravity waves, and thermohaline circulation (Dearborn 1992; Boothroyd et al. 1994; El Eid 1994; Charbonnel 1995; Nollett et al. 2003; Denissenkov & Tout 2003; Busso et al. 2007; Eggleton et al. 2008; Palmerini et al. 2011). In all cases, the reliability of the deep mixing probe depends on our knowledge of the rates of the nuclear reactions determining the 16O/17O ratio in the H-burning regions, i.e, 16O(p, γ)17F, 17O(p, γ)18F and 17O(p, α)14N. The last two reactions have recently been studied by the LUNA collaboration (Scott et al. 2012; Di Leva et al. 2014; Bruno et al. 2016) to obtain precise underground measurements of their cross sections at relatively low energy. At variance with the (p, γ) channel, for which negligible variations with respect to previous investigations have been found, the (p, α) rate has been substantially revised. The latter reaction is the main destruction channel of 17O. Thanks to the significant background reduction of the underground laboratory, a new direct determination of the 64.5 keV resonance strength has led to the most accurate value to date, ωγ = 10.0 ± 1.4stat( ± 0.7syst) neV. The 64.5 keV resonance dominates the reaction rate for temperatures below 100 MK. The (bare) proton partial width of the corresponding state at EX = 5672 keV in 18F is Γp = 35 ± 5stat( ± 3syst) neV, which is about a factor of two higher than previously claimed. As a consequence, the 17O(p, α)14N reaction rate in the temperature range most relevant for the hydrostatic H burning, 20 <T/ MK < 100, is about a factor of two higher than previously estimated. Larger temperatures may be attained in explosive H burning, such as in the case of nova events (Di Leva et al. 2014), and in the hot bottom burning (HBB) process occurring in super-AGB stars (Siess 2010; Ventura et al. 2012; Doherty et al. 2014). For T> 100 MK, however, the influence of the 64.5 keV resonance on the total reaction rate is negligible. In Fig. 1, the corresponding variation of the equilibrium value of 16O/17O (Eq. (1)) as function of the temperature is compared to those obtained by adopting the 17O(p, α)14N rates reported in the popular compilations NACRE (Angulo et al. 1999) and STARLIB (Iliadis et al. 2010; Buckner et al. 2015). As is immediately seen, the revision of the 17O(p, α)14N rate implies equilibrium values of the 16O/17O ratio, which are up to a factor of 2 larger than those obtained so far.
In this paper we discuss the expected variations of the 16O/17O at the surface of stars with different masses. In particular, we consider the effects induced by the major deep mixing episodes, such as the dredge-up events and the extra-mixing process that is likely operating in bright low-mass RGB stars and, perhaps, also during the AGB phase. We do not address here the impact on the HBB, which is an important nucleosynthesis episode occurring in massive AGB stars. Because of the complexity of this phenomenon, which is largely not yet fully understood, we decided to dedicate a companion paper to the discussion of the impact of the revised 17O(p, α)14N rate on the HBB (Lugaro et al. 2017).
A variation of the stellar 17O yields is also expected. According to the extant chemical evolution models (see, for example, the recent review of Nittler & Gaidos 2012; or CGE models discussed in Prantzos et al. 1996; Romano & Matteucci 2003; Kobayashi et al. 2011), the average 17O abundance in the interstellar medium (ISM) should increase with time, mainly because of the ejecta of intermediate and massive stars. We show that with the revision of the 17O(p, α)14N reaction rate, the 17O yields are substantially reduced. As a consequence, the rate of growth of the 17O in the ISM should be slower than previously estimated.
We computed all the stellar models presented in this paper by means of the latest release of the full-network stellar evolution code (FUNS, Straniero et al. 2006; Piersanti et al. 2013). Except for the 17O(p, α)14N, all the rates of the other reactions involved in the H burning are from Adelberger et al. (2011). When not specified, the initial composition of the models is solar (Lodders et al. 2009). It implies Z = 0.014 and Y = 0.27. The various uncertainties affecting stellar models and the related nucleosynthesis results, including those due to the treatment of mixing, are discussed in some detail in Sect. 2 of Straniero et al. (2014; see also Sects. 4 and 5 in Lebzelter et al. 2015). More details on the theoretical estimation of the O isotopic ratios can be found in several papers, including Dearborn (1992), Boothroyd et al. (1994), El Eid (1994), Stoesz & Herwig (2003), Karakas & Lattanzio (2014), Halabi & Eid (2015). We used the same stellar evolution code (FUNS) as in Cristallo et al. (2015). Nevertheless, the 17O abundances and yields presented in this paper slightly differ from the corresponding values reported in the full-network repository of updated isotopic tables & yields (FRUITY) because we updated the initial composition (Lodders et al. 2009; instead of Lodders 2003) and several reaction rates, in particular, those of the CNO cycle.
Equilibrium values of the 16O/17O vs. temperature (see Eq. (1)). The black curve was obtained by adopting the revised rate of the 17O(p, α)14N reaction (median values of Bruno et al. 2016) and the two black dashed lines show the recommended maximum and minimum values compatible with the experimental data, which corresponds to the 1σ error bar of the measured nuclear cross section. For comparisons, the blue, red, and green lines show the results obtained by adopting the 17O(p, α)14N rate from Buckner et al. (2015), Iliadis et al. (2010), and Angulo et al. (1999), respectively.
In this section we discuss the variations of the 16O/17O predicted by models of low- and intermediate-mass stars after the major dredge-up episodes, as due to the revision of the 17O(p, α)14N reaction rate. The possible effects on low-mass stars undergoing RGB or AGB extra-mixing episodes are also discussed.
The first appearance at the surface of a star of the chemical variations caused by the internal nucleosynthesis occurs just after the exhaustion of the central hydrogen when the star leaves the main sequence to become a red giant. A convective instability develops in the most external layers and quickly extends down to the region where the H burning took place. This is the so-called first dredge up (FDU).
Oxygen isotopic ratio in the H-rich envelope of a 2.5 M⊙ newborn red giant star, just before the occurrence of the FDU. The models were computed with different 17O(p, α)14N reaction rates and/or different initial compositions (see the legend). The shaded area shows the portion of the stellar envelope that are mixed at the time of the FDU.
The solar value of the 16O/17O is 2700 (Lodders et al. 2009). Models of intermediate-mass stars (2 <M/M⊙< 8) show that after the FDU this isotopic ratio is reduced down to values between 200 and 500, depending on the initial mass and composition, essentially because of 17O production. In more detail, these stars develop a rather extended convective core at the onset of the core H burning, corresponding to the main sequence of the HR diagram. The central (maximum) temperature is typically between 20 and 30 MK and the corresponding equilibrium value of the 16O/17O ratio (<100) is established in the whole convective core. Later on, at the epoch of the FDU, the external convective instability penetrates the portion of the core that was efficiently mixed when the star was on the main sequence. As a consequence, the surface abundance of 17O increases, while that of 16O slightly decreases.
In Fig. 2 we plot the 16O/17O profile within the H-rich envelope of a newborn giant star with 2.5 M⊙ and solar metallicity. The three compositional profiles, which are all sampled just before the onset of the FDU, were obtained under different assumptions for the 17O(p, α)14N reaction rate and/or different initial composition: the Iliadis et al. (2010) rate and solar 16O/17O (red line), the new rate (median values of Bruno et al. 2016) and solar 16O/17O (black line), and the new rate and 16O/17O lower than solar (black dashed line). This figure clearly shows that in the most internal region of the envelope, where the H burning attained the CNO equilibrium, the 16O/17O does not depend on the initial composition, but is fixed by the production and destruction rates of the 17O (Eq. (1) and Fig. 1). Therefore, the abundance ratio in the deepest layer of the H-rich envelope of a giant star only depends on the reaction rates and on the maximum temperature previously experienced. On the contrary, the O isotopic ratio in the external envelope reflects the initial composition. Later on, the external convection penetrates the internal region, modifying the surface composition. The shaded area in Fig. 2 shows the region that is mixed by the convective instability at the epoch of the FDU.
The maximum temperature attained in the deepest layer reached by the FDU varies with the initial stellar mass and composition. For a fixed chemical composition (same initial helium and metallicity), the larger the stellar mass the larger the temperature at the innermost convective boundary. In contrast, the ashes of the H burning are mixed with the material in the cooler external envelope with the initial composition and the larger the envelope mass the smaller the variation of the composition at the stellar surface. The combination of these two effects leads to the plots reported in Fig. 3, in which we show the surface value of the 16O/17O ratio after the FDU versus the initial stellar mass. For convenience, the values of the post-FDU 16O/17O are listed in Table 1. In all cases, a sharp decrease of the 16O/17O ratio is found for 1.2 <M/M⊙< 2.5, followed by a shallower increase for more massive stars. In low-mass stars (M< 1.2M⊙), the convective core disappears at the onset of the main sequence. In that case the 16O/17O does not change after the FDU.
The maximum difference of 20% between models, which are obtained with the old and new 17O destruction rates, is found at M = 2.5M⊙. The change implied by the new rate may be compensated by varying the initial O composition (dashed line in Fig. 3).
Post-FDU 16O/17O at the surface of models with different initial mass and different rates and/or initial composition (see the legend).
During the early-AGB phase, intermediate-mass stars (M ≥ 4M⊙) experience a second dredge-up episode. This episode occurs when the H-burning shell is temporarily switched off and the convective envelope can penetrate the H-exhausted core. In this case, H-depleted material enriched with the ashes of the H-burning is brought to the surface. At variance with the FDU, the change of the 16O/17O at the surface of the star is small. The situation is illustrated in Fig. 4: in the upper panel we show the evolution of the 16O/17O at the surface of a 6 M⊙ model (solar initial composition) up to the early-AGB phase, while in the lower panel we report the evolutions of the corresponding mass fractions of 16O (solid) and 17O (dotted). The red lines refer to the models calculated by adopting the Iliadis et al. (2010) rate for the 17O(p, α)14N reaction, while the black lines represent models obtained with the new LUNA rate. In both cases the variations at the stellar surface are largely dominated by the large increase of the 17O abundance caused by the FDU. Later on, the H burning restarts whereas the He-burning shell periodically undergoes recursive thermonuclear runaways (i.e., thermal pulses; TP). Then, third-dredge-up episodes occur after each thermal pulse, except for the first and a few final TPs. As for the second dredge up, the convective envelope penetrates the H-exhausted core. However, the variation of the O isotopic ratio caused by the third dredge up is generally small. An increase of the 16O/17O is actually found in low metallicity models owing to the dredge up of primary 16O produced by the He burning (see, for example, O abundances listed in the FRUITY database Cristallo et al. 2015), but this phenomenon is independent of the adopted CNO reaction rates.
Evolution of the two lighter oxygen isotopes in a 6 M⊙ model (solar initial composition). Upper panel: 16O/17O ratio. Lower panel: 16O (solid) and 17O (dotted). Red lines refer to the models calculated by adopting the Iliadis et al. (2010) rate for the 17O(p, α)14N reaction, while black lines represent models obtained with the new LUNA rate (Bruno et al. 2016). tf = 68 Myr corresponds to the age of the last computed model (end of the early AGB).
It is generally accepted that the FDU alone cannot account for the CNO abundances measured in the brightest RGB stars with M < 2M⊙ and that an extra-mixing process should be at work in the upper RGB (Charbonnel 1995). In particular, the 12C/13C ratio in these stars is substantially lower than predicted by stellar models after the occurrence of the FDU. On the contrary, model predictions are in good agreement with the C isotopic ratios measured in more massive RGB stars as well as in faint RGB stars with low mass. For instance, values of 12C/13C < 20 are commonly found in low-mass RGB stars that are brighter than the so-called RGB bump, i.e., the peak in the RGB luminosity function due to the temporary stop of the luminosity growth that occurs when the H-burning shell approaches the chemical discontinuity left by the FDU (Gilroy & Brown 1991; Gratton et al. 2000; Abia et al. 2012). In contrast, model predictions for the 12C/13C ratio after the FDU are always >20. In principle, the O isotopic ratios may also be affected by the extra mixing, although there is some observational evidence against such a possibility (Abia et al. 2012). In this context, the new (stronger) rate of the 17O(p, α)14N reaction can affect the variation of the 17O at the stellar surface. In Fig. 5 we report C and O isotopic ratios in the innermost layers of the H-rich envelope of a RGB-bump model with initial mass 1.5 M⊙ and initial solar composition. Sizeble variations of C, N, and O isotopes, as due to H burning, occur at m ≤ 0.277M⊙. Since the internal boundary of the convective envelope is at m = 0.292M⊙, extra mixing is needed to bring the product of the CNO nucleosynthesis into the convective zone. In the same figure, the temperature profile is also reported (red line). A modification of the 16O/17O ratio would require a much deeper extra mixing than that needed to explain the C isotopic ratio commonly observed in bright low-mass RGB stars.
C and O isotopic ratios in the innermost portion of the H-rich envelope of a RGB-bump model with M = 1.5M⊙ (solar initial composition): 12C/13C (black solid line), 16O/17O (short dashed line), and 16O/18O (long dashed line). The red line represents the temperature profile (in MK).
Since the actual physical process that is capable of driving an efficient mixing below the convective envelope in giant stars is still largely unknown, a few free parameters are usually introduced to investigate the effects of these phenomena. We do not pretend to discuss these effects or even the nature of the extra-mixing processes. Several paper have been already dedicated to this subject (see, e.g., Dearborn 1992; Boothroyd et al. 1994; El Eid 1994; Charbonnel 1995; Nollett et al. 2003; Denissenkov & Tout 2003; Busso et al. 2007; Eggleton et al. 2008; Charbonnel & Lagarde 2010; Palmerini et al. 2011, and references therein). The models presented here just aim to highlight possible effects of the revised 17O(p, α)14N rate. Starting from the RGB-bump model shown in Fig. 5, we switched on an artificial extra-mixing process extending from the convective boundary down to a maximum temperature Tmax. We set the mixing velocity to 100 cm/s, which is about 2 orders of magnitude slower than that in the convective region. Mixing velocities of this order of magnitude are expected in the case of thermohaline mixing (Charbonnel & Zahn 2007) and magnetic buoyancy (Palmerini et al. 2009), while somewhat lower values have been estimated for rotation induced mixing (Palacios et al. 2006). We verified that the C and O isotopic ratios at the stellar surface does not substantially depend on the assumed mixing velocity, but depends mainly on Tmax. In Fig. 6 we show the evolution of the C and O isotopic ratios for Tmax = 20, 21, and 23 MK. The most extreme case implies an extra-mixing zone extending from the internal convective boundary down to the outer border of the H-exhausted core. After the activation of the extra mixing, in all three cases the 12C/13C quickly drops below 20. The resulting C isotopic ratios are in good agreement with the observed values for the brightest low-mass RGB stars. In contrast, one only finds a non-negligible enhancement of the 16O/18O in the most extreme case, whilst in spite of the stronger rate of the 17O(p, α)14N reaction, the 16O/17O practically remains unchanged.
Evolution up to the RGB tip of C and O isotopic ratios in the 3 models with extra mixing described in the text. The maximum temperature attained by extra mixing is Tmax = 20, 21, and 23 MK (black, red, and blue lines, respectively). In all cases, the fluid velocity in the extra-mixing zone is about 1/100 of that in the fully convective envelope. The evolutionary timescale has been properly rescaled to tf = 2.91 Gyr, which corresponds to the onset of the core-He burning. The FDU starts at log t/ (t−tf) ~ 1, while the extra-mixing process is activated just after log t/ (t−tf) ~ 1.7, namely, the epoch of the RGB bump.
In principle, even hotter regions may be attained by an AGB extra mixing. However, the actual occurrence of this process is still largely debated (see, for example, Lebzelter et al. 2008; Lederer et al. 2009; Karakas et al. 2010; Busso et al. 2010; Stancliffe 2010). Nevertheless, in order to investigate the effects of the revised rate of the 17O(p, α)14N reaction on the O isotopes of AGB stars possibly undergoing extra mixing, we extended the computation of the 2 M⊙ model up to the AGB tip. An AGB extra mixing extending down to Tmax = 40 MK was activated since the first termal pulse. In addition, a RGB extra mixing (Tmax = 22 MK) was also activated after the occurrence of the RGB bump. In both cases the average fluid velocity in the extra-mixing zone was set to 100 cm/s. The result is shown in Fig. 7. The 16O/17O should increase in the case of an AGB extra mixing, contrary to the variations induced by the FDU and, to a lesser extent, by the RGB extra mixing. The reason for this increase is simple: after the FDU, the 16O/17O drops down to ~ 300, while at T = 40 MK the equilibrium value of this ratio is ~ 1870 (see Fig. 1). Therefore, as a consequence of the AGB extra mixing, the material with high 16O/17O of the most internal portion of the H-burning shell is mixed with the envelope material that is characterized by low 16O/17O. This effect is weaker for stars with smaller initial mass because the 16O/17O after the FDU is higher (see Fig. 3). With previous 17O(p, α)14N reaction rates (e.g., Iliadis et al. 2010), the equilibrium values of the 16O/17O would be a factor of two smaller, thus reducing the overall increase of this isotopic ratio at the stellar surface. As a whole, in spite of the larger 17O(p, α)14N rate, the variation of 16O/17O caused by the AGB extra mixing is much smaller than those of the other CNO isotopic ratios, such as 12C/13C, 14N/15N, and 16O/18O. At the beginning of the C-star phase, i.e., when C/O = 1, 16O/17O is ~ 400, which is a 30% larger than the value obtained with the rate provided by Iliadis et al. (2010). We note that C stars affected by AGB extra mixing should show extreme values of 14N/15N (>2 × 104) and 16O/18O (>2 × 103), while the 12C/13C should be ≤20.
Evolution up to the AGB tip of C, N, and O elemental and isotopic ratios in a 2 M⊙ model with both RGB and AGB extra mixing. In the first case the maximum temperature was fixed to Tmax = 22 MK, while in the latter Tmax = 40 MK (see text for further details). The evolutionary timescale was rescaled to tf = 1.196 Gyr, which corresponds to the age of the last computed model (AGB tip). The FDU occurs at log t/ (t−tf) ~ 0.7, while some effect of the RGB extra mixing is visible a bit later. Finally the combined actions of the and the AGB extra mixing arise at log t/ (t−tf) > 2.8.
Oxygen-17 is a secondary product of the H burning and, therefore, all stars contribute to its synthesis. The major contribution to the pollution of the interstellar medium likely comes from massive stars (M> 10M⊙). The winds of red giant stars of intermediate and low mass provide further contributions on a longer timescale. Extant chemical evolution models show that the abundance of 17O in the ISM of the galactic disk increases with time (see the review of Nittler & Gaidos 2012, and references therein). This expectation is substantially confirmed by the abundance analysis of stars belonging to stellar populations of different ages and in the ISM (see, e.g., Nittler & Gaidos 2012; Lebzelter et al. 2015). The 17O increase with time is stronger toward the Galactic center than in the outermost regions because of the increase of the stellar density at short Galactic radius and the consequent increase of the pollution rate (see Figs. 1 and 2 in Nittler & Gaidos 2012). Extant nucleosynthesis models show that stars with mass between 2 and 20 M⊙ should release a few 10-5M⊙ of 17O. Because 17O is a secondary isotope, its production is higher at larger metallicity. More precisely, the yield depends on the initial C+N+O abundance.
As for intermediate-mass stars, in models of massive stars the amount of 17O in the envelope is also enhanced as a consequence of the FDU. Here, we refer to the progenitors of type II supernova, which retain a H-rich envelope up to the final explosion. On the contrary, the 17O is destroyed in the H-exhausted core. Then, the 17O in the envelope remains unchanged after the FDU and until the core collapse. Also the final explosion does not affect the 17O yield; see, e.g., Limongi et al. (2000, 2001), where both pre- and post-explosive yields are discussed, or Kobayashi et al. (2011), where it is shown that the 17O yield does not depend on the explosion energy. Indeed, the H-rich envelope expands prior to the passage of the shock wave, so that the explosive nucleosynthesis is inhibited. In practice, a reasonable estimation of the 17O yield could be obtained by multiplying the 17O mass fraction after the FDU by the total mass of H-rich material ejected during the long hydrostatic evolution (by stellar wind) or as a consequence of the final explosion. Therefore, the adopted mass loss rate after the FDU, and the details of the final explosion, are not critical to modeling the 17O yield in massive stars. This approximation is reasonable for most massive stars, except in the case of an early ejection of the whole envelope that stops the growth of the H-exhausted core, as occurs in Wolf-Rayet stars. In contrast, there is a major uncertainty because of the formation of a semi-convective shell instability during the core H burning, when the fully convective core recedes and leaves a decreasing H profile. As is well known, depending on the adopted mixing scheme, the core He burning may start when the star is still a blue compact structure or after it has expanded and become a red giant (see, e.g., Langer & Maeder 1995, Fig. 3, in particular). In the former case, the occurrence of the FDU is delayed; more precisely, it occurs after the end of the core-He burning. In this case the amount of H-rich material lost before the FDU may be greater and, therefore, the total yield is smaller.
In the models of massive stars presented here, we adopted a semi-convective scheme, i.e., the degree of mixing is calibrated in order to establish convective neutrality1 in the whole semi-convective layer. In this case the mixing efficiency is substantially limited, so that the FDU occurs soon after the main-sequence phase. As a result, most of the envelope mass is lost after the occurrence of the FDU. Then, we computed three models with solar initial composition and masses 12, 15, and 20 M⊙, which are representative of the most common type II supernova progenitors. We stopped the computation at the end of the C-burning phase. At that time, the residual stellar lifetime is so short that the composition of the H-rich envelope and the H-exhausted core mass remain frozen up to the final explosion. Therefore, we obtained the total yield by adding the 17O mass contained in the H-rich envelope of the last computed model to the amount of 17O cumulatively ejected before the end of the C-burning phase.
The resulting yields are reported in Table 2; they are net yields, namely the difference between the 17O mass ejected during the whole stellar lifetime and the initial total 17O mass. Results for different 17O(p, α)14N reaction rates are provided in Cols. 2 and 3. Once the different initial compositions and reaction rate libraries are considered, the yields listed in Col. 2 are in good agreement with those reported by Kobayashi et al. (2011) and Chieffi & Limongi (2013; non-rotating models). Yields of a selected sample of low- and intermediate-mass stellar models with solar composition, as described in the previous sections, are reported as well. In this case all the models were evolved up to the AGB tip and no extra-mixing processes were included.
The new LUNA rate implies a sizeable reduction of the net yield of 17O of up to a 40%. This result is almost independent of the initial metallicity or He content. The impact on models of Galactic chemical evolution deserves further investigation. In particular, we expect a slower rate of 17O pollution of the ISM (see the discussion in Sect. 4).
We have revised the theoretical predictions of the 16O/17O ratios and of the 17O yields from stars in a wide range of initial masses. We based all the computations on the new recommended values of the 17O(p, α)14N reaction rate as described by Bruno et al. (2016). Bruno et al. (2016) also provide an upper and a lower limit for this reaction. As seen in Fig. 1, the 16O/17O values found using rates from previous compilations are outside the updated error band. Similarly, the uncertainty implied for the 17O yields is much smaller than the difference between the revised values and the previous evaluations.
Reaction rates with uncertainties at the level of a 20% (or lower), as recently achieved by the LUNA collaboration for the 17O(p, α)14N and 17O(p, γ)18F reactions, are required to constrain the efficiency of the various deep-mixing episodes operating in stars of various masses. Thanks to the improved accuracy of the relevant reaction rates, it will become possible to check the reliability of the numerical algorithms used to model stellar convection and other dynamical and secular instabilities in stellar interiors. In this context, comparisons of model predictions with 16O/17O ratios in giant stars is of primary importance, providing calibration tools for the various free parameters whose values are not fixed by the theory. Similarly, O-rich, pre-solar grains may also provide useful constraints for the models (Lugaro et al. 2017). The revision of the 17O yields could have a major impact on Galactic chemical evolution studies. In particular it should help the interpretation of the oxygen isotopic composition of various Galactic components, such the Sun, giant stars, and diffused matter. In this context, Lebzelter et al. (2015), analyzing post-FDU measurements of the O isotopic ratios in RGB stars belonging to Galactic open clusters, conclude that the O isotopic composition of the Sun does not represent the original composition of the gas from which these stars formed. In particular, they were able to reproduce the observed O abundance by assuming smaller-than-solar initial O isotopic ratios. Possibly, this occurrence may be explained in the framework of Galactic chemical evolution. Indeed, as shown by, for example, Prantzos et al. (1996), Romano & Matteucci (2003), Kobayashi et al. (2011), Nittler & Gaidos (2012), the 16O/17O ratio decreases with time, so that stars that are younger than the Sun should have been formed, on the average, from a gas characterized by smaller oxygen isotopic ratios. Models obtained with the new and higher rate of the 17O(p, α)14N reaction, which implies larger 16O/17O after the FDU, confirm and even reinforce the need of smaller-than-solar initial 16O/17O to reproduce the ratios observed in post-FDU giants belonging to Galactic open clusters. For instance, we obtained the models represented with dashed lines in both Figs. 2 and 3 by assuming an initial 16O/17O = 1797; this value is lower than the solar value (2700) and roughly corresponds to the weighted average 16O/17O ratio of the interstellar medium in the region of the Galactic disk closer to the Sun (between 6 and 10 kpc from the Galactic center), as derived from measurements of CO molecular lines (Wouterloot et al. 2008; see also Penzias 1981). On the other hand, Kobayashi et al. (2011) found that their GCE model underestimates the solar 16O/17O and conclude that a reduction of the 17O yields could solve this problem. As shown in Sect. 3, the revision of the 17O(p, α)14N reaction rate goes in this direction and, therefore, it could alleviate the problem.
As a whole, more stringent constraints to important phenomena, such as stellar migration or the observed composition gradients along the Galactic disk, and to the nucleosynthesis in general are expected by comparing the observed abundances of oxygen isotopes with predictions of chemical evolution models based on more accurate oxygen yields.
∇adiabatic−∇radiative = 0, where .
We are indebted to Maria Lugaro and Paola Marigo for their careful reading of the manuscript, comments, and suggestions. We thank Thomas Lebzelter, Carlos Abia, Inma Dominguez, and Marco Limongi for the many helpful discussions about 16O/17O in RGB, AGB, and massive stars.


? Rick Wilking Image: File photo of Southwest Airlines jets waiting on the tarmac at Denver International Airport in Denver A Florida man who was arrested for groping a woman on a Southwest flight bound for New Mexico told federal agents that President Trump said it's permissible to grab women by their "private parts."
Bruce Michael Alexander, 49, was arrested Sunday and charged with abusive sexual contact after a woman on a flight from Houston accused him of touching her "around her bra line" and elsewhere, according to a criminal complaint.
The woman said she had fallen asleep on the flight and woke up to the passenger behind her grabbing "the right part of her right breast," the complaint said.
She assumed it was an accident, but about a half hour later she "felt fingers slowly grab the back of her arm, squeezing above the elbow then slowly and 'attentively' grab her right side, again around her ribs and bra line," according to the complaint.
That's when she confronted the man behind her. She asked him why he thought it was all right to touch her like that, and asked a flight attendant to help her change seats.
Alexander didn't admit to touching the woman, but after he was placed in handcuffs, he said "that the President of the United States says it's ok to grab women by their private parts," the complaint said.
He was apparently referencing a 2005 video in which President Donald Trump can be heard saying: "And when you’re a star, they let you do it. You can do anything. Grab 'em .... ."
A statement from Southwest said customer service supervisors and police were requested to meet the flight "due to reports of a customer’s alleged inappropriate behavior onboard."
Alexander is due in court Tuesday, according to a news release from the U.S. Attorney's Office. He could face up to two years in prison and a $250,000 fine.


18 20 13 3 8 26 14 24 20 14 23 1 16 17 13 3 5.
In the nineties, new encryption software that could protect telephone conversations, faxes, and e-mails from unwarranted monitoring was coming on the market, but the programs could also block entirely legal efforts to eavesdrop on criminals or potential terrorists. Under McConnell's direction, the N.S.A. developed a sophisticated device, the Clipper Chip, with a superior ability to encrypt any electronic transmission; it also allowed law-enforcement officials, given the proper authority, to decipher and eavesdrop on the encrypted communications of others. Privacy advocates criticized the device, though, and the Clipper was abandoned by 1996. "They convinced the folks on the Hill that they couldn't trust the government to do what it said it was going to do," Richard Wilhelm, who was in charge of information warfare under McConnell, says.
But that's not actually what happened. In fact, almost everything about this quote -- the whos, the whys and the whens -- is not merely slanted in its interpretation, but factually contradicted by the public record.
More generally, while Congress (presumably the Hill on which the folks referred to above resided) held several hearings on the subject, it never actually enacted (or even voted on) any cryptography legislation during the 1990's. Instead, the relaxation of cryptography export regulations (the lever through which the government controlled US encryption software and hardware) was entirely a product of the executive branch. Department of Commerce export regulations that took effect at the beginning of 2000 effectively eliminated the major controls on mass-market and open source encryption products, and in 2004 the rules were relaxed even further. In other words, the current policy promoting widely available encryption has been actively supported not just by the previous administration, but by the present one as well.
Government attempts in the 1990's to control cryptography were ultimately doomed not by some kind of weak-kneed policy capitulation (even if some in the national security community might now find it convenient to portray it as such), but by inexorable advances in technology (particularly what Larry Lessig calls "west coast code"). Even before the hardware-only Clipper program was announced, the performance of software-based encryption on general purpose computers had become competitive with that of expensive purpose-built encryption chips. At the same time, growth in the largely open-source-based networked computing world increasingly depended on reliable and inexpensive communications security, something fundamentally incompatible with the key escrow scheme underlying Clipper. Coupled with the inherent risk that a central encryption key database would itself become a target for foreign intelligence agents, it became apparent to just about everyone by the end of the decade that decontrol was the only viable policy option.
Tellingly, even after the attacks of September 11th, 2001 the Bush administration made no serious attempt to control or otherwise reign in the public availability or use of strong encryption. Indeed, its only action on cryptography policy came in 2004, when it further liberalized the few remaining export controls on the technology.
It's unfortunate that the New Yorker failed to check the facts about Clipper, but that's not the central concern here. Intelligence agencies (and their officials) largely operate under a thick veil of legally enforced secrecy, carrying with it a special obligation to be scrupulously truthful in their analysis. Should we trust them to be more forthright than the former official quoted in the excerpt when the facts are not so easily checked? We often have no choice.
When I published my Clipper paper in 1994, the NSA -- to its great credit at the time -- immediately acknowledged the problems, despite the embarrassment the whole affair no doubt caused them. And that is precisely how we must expect our intelligence agencies to behave. Intelligence spun to serve a political narrative isn't intelligence, it's just politics.
Photo above: Mykotronx MYK-78T Clipper Chip, as installed in an AT&T TSD-3600E encrypting telephone. More Clipper photos here.


Despite vocal efforts by some foreign policy hawks to view the war on drugs as an extension of the war on terror, the emerging consensus—even among the political establishment—is that the war on drugs has been a dismal failure. Drug production—and body counts—surge in Latin America, opium is a staple crop in Afghanistan despite the presence of tens of thousands of occupying troops, and anti-drug policies that have helped put hundreds of thousands of non-violent offenders behind bars have had no discernible impact on usage. But for much of the rightwing establishment, drug prohibition is just like any other war: deserving of uncritical support even in the face of defeat. Read article.
With President Obama’s announcement that he would withdraw 10,000 U.S. troops from Afghanistan in 2011 and an additional 23,000 the following year, the president effectively ruptured the uneasy alliance his administration had maintained with prominent foreign policy hawks and neoconservatives ever since his progressive base began to question his escalation of the war. However much Obama’s conservative critics accused him of “dithering” in advance of his earlier decision to “surge” U.S. forces in the country, they were nonetheless among his more reliable backers when it came to the war in Afghanistan. This alliance, however, is no more. Militarist Monitor.
The U.S. ambassador to Afghanistan, Iraq, and the United Nations during the Bush presidency, Khalilzad is president of the international consulting firm Khalilzad Associates and an outspoken supporter of aggressive U.S. support for toppling Mideast regimes caught up in the “Arab Spring” as part of an effort to contain Iran.
Gompert, a former vice president of the RAND Corporation known for his hawkish views on defense, served briefly as President Barack Obama’s acting director of national intelligence before becoming a director at Pentagon contractor Global Integrated Security.
Rubin, a “scholar” at the American Enterprise Institute who has attacked what he call’s Right Web’s “fake, conspiracy riddled biographies,” views the revolt in Egypt through the lens of Iran’s Islamic revolution.
Hirsi Ali, a fellow at the American Enterprise Institute who has a made a career denouncing Islam, argues that Egypt’s Muslim Brotherhood may be more dangerous than Al Qaeda precisely because it has given up armed struggle.
Garner, the erstwhile “mayor of Baghdad,” has capitalized on his experiences in Iraq to pursue oil deals in Kurdish areas of the country.
In the face of growing congressional criticism over the legal basis for the Libyan War, Barack Obama received a lifeline from two Senate allies: John Kerry and John McCain.
Despite Barack Obama's announcement of a gradual withdrawal from Afghanistan, the reality is that U.S. troops are far from coming home.
By announcing a small troop drawdown, but refraining to set a deadline for full troop withdrawal, Barack Obama is trying to stake out a middle ground in the Afghan war debate.
The lengthening U.S. intervention in Libya has prompted Congress to angrily claim President Obama is not complying with the 1973 War Powers Act.


Target: All nationalities | Level: Master degree | Discipline: Conservation Biology | Host Institution: Queensland University in Australia | Expires in 4 days!
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Councillor Terry Kelly: "RUMOURS OF THE DEMISE OF THE LABOUR PARTY ARE GREATLY EXAGGERATED" APOLOGIES TO MARK TWAIN - LABOUR WIN OLDHAM BY ELECTION.
"RUMOURS OF THE DEMISE OF THE LABOUR PARTY ARE GREATLY EXAGGERATED" APOLOGIES TO MARK TWAIN - LABOUR WIN OLDHAM BY ELECTION.
How do the keyboard swindlers explain this? It is very hard indeed to find a more difficult scenario for the Labour Party to overcome than that which existed at yesterday’s Oldham West By Election, caused by the death of Michael Meacher who was a much loved and very talented MP. The forces lined up against Labour, ‘some shamefully from its own side’ were enormous, malevolent and mainly driven by a desire to tear down Jeremy Corbyn’s leadership. Make no mistake about it, to the right wing establishment in the UK as well as the time serving careerists in his own party Mr. Corbyn is a very dangerous man. In Corbyn’s Labour Party refreshingly, your name, your wealth and your connections mean nothing. Ability, hard work and a Socialist ethic have become the ticket to power and influence. The changes have brought about a welcome upheaval in the party ranks, our numbers have grown enormously making us the party with more members than all the other parties put together and that explosion in the membership coincided with the election of the left wing Socialist Leader Jeremy Corbyn, thus making any accusation of Labour not being a Socialist Party sound absurd.
Oldham West was a triumph for the people over their hidebound capitalist exploiters, the Tories, The Libdems, UKIP and the SNP, as well as the right wing press which now shamefully includes The Guardian. To win 62% of the vote against such hostility was a remarkable achievement and it serves to remind us that the UK is a Socialist country. As is now the norm we have the usual smears being thrown around by the opponents of Labour when we win. UKIP cry foul and bad losers are complaining about bullying and intimidation over the Syrian bombing vote, some MP’s clearly see their positions as precarious based on the fact that the massive surge in membership was down to Corbyn’s Leadership victory and they have been doing what they can to bring him down, there can be no doubt that the vast majority of Labour Party members are opposed to bombing Syria and they have a voice. For those Labour members who are new I would urge you to check the rules about de-selection of sitting MP’s. This is a long standing procedure which is perfectly legal, democratic and is the very essence of democracy. As far as the nasty and vicious emails, texts and threats are concerned about Syria I would urge people to consider which political party has the worst by far reputation for such behaviour, that is the SNP. Now consider whether the notorious SNP Cybernats would send such filth to Labour MP’s who voted for bombing, is that difficult to answer. Perhaps those who intend to investigate these matters should be looking North.
Your delusions know no bounds but that's the trouble with delusions I guess. How you can possibly claim that the Oldham by-election confounds the SNP is simply bizarre. As for trying to suggest that SNP supporters are masquerading as infuriated Corbynites and anti-war protestors to Troll Labour MPs proves your mind resembles Esher's Relativity but not in a good way. There's a great series of programmes on C4 called The Secret Lives of 4, 5 and 6 year olds. It brings a whole new meaning to the politics of the playground. You'd fit right in.
you only won Oldham because the SNP didn't stand a candidate.
It was a big disappointment for UKIP, the Tories and the SNP and there is more to come.
Joseph Tierney Friday, December 04, 2015 8:01:00 p.m.
Labour's magnificent victory in The Oldham By Election was a huge blow to the SNP who would prefer either their fellow nationalists of UKIP or the Tories to win. The SNP Cybernats number one target has always been Labour and it makes perfect sense for these thugs to target Labour at every opportunity and this is what they are doing, we have seen it before. The SNP created all this hatred and anti English racism and now we are seeing how hard it is to stop it. People who deny its existence like you Mr. Tierney are worse than the perpetrators.
The SNP don't target labour, why would they flog a dead horse. And for the record they didn't kill the horse it committed suicide in Iraq.
"the snp don't target Labour" does your carer know you are writing this?. The snp Cybernats would target their own grannies and they are up to their necks in this as well.
the snp don't target Labour" does your carer know you are writing this?. The snp Cybernats would target their own grannies and they are up to their necks in this as well.
Up to their necks in what councillor? you appear somewhat incoherent. There is no need for the SNP to continue to flog a dead horse. think about it.
Anyone who thinks that the SNP are not targeting Labour is either a liar or is not thinking straight or perhaps both.
I See that you chose not to post my comment of last night.
It's not difficult to understand. If you send a post which makes an argument without being abusive or repetitive it will be printed.


Q: Think of the last name of a famous person in entertainment. The first two letters of this name are a symbol for one of the elements on the periodic table. Substitute the name of that element for the two letters, and you will describe the chief element of this person's work. What is it?
Edit: Alanis Morrisette has a song entitled "Isn't it Ironic"
Blaine, I think you mean “Aluminiumanis.” In honor of the Olympics, let's let that element run its full course.
I've been trying combinations for a while now. I was under the impression Zinc was an aggregate of minerals. To the contrary, it is part of the transition metals.
I would include a chemistry joke, but all the good ones Argon.
The new puzzle is up. I think I've figured it out. It's asking for a the name of a certain entertainer.
Funny thing, I was thinking of a show on which this person used to be a regular - and it's not even on tonight!
...concerning the joke clue you left, "Aluminumanis?"; working that backwards you would get "Alanis". I know of an entertainer with a first name of Alanis, Alanis Morissette; but who has Alanis for a last name?
Too polite to mention Alanis Morissette had a son called "Ironic"?
Replace all the letters but one in the performer's FIRST name with the symbol for the element THEY spell, add one letter, and you name a program on which the performer worked.
I thought of that one too. Interesting alternative element to this answer.
Just curious... What's libertarian math? No limits?
I like this puzzle a lot. I am grateful I figured it out in a timely way. But, I am hard pressed to come up with a good clue that would not be a dead give away.
Tom Lehrer's The Elements includes the first 102 elements of the periodic table. Since 1959, scientists have named a dozen more. Specifically: Lawrencium (Lr), Rutherfordium (Rf), Dubnium (Db), Seaborgium (Sg), Bohrium (Bh), Hassium (Hs), Meitnerium (Mt), Darmstadtium (Ds), Roentgenium (Rg), Copernicium (Cn), Flerovium (Fl), and Livermorium (Lv).
Does anyone know when Romney will be selecting his Vice President?
I don’t want to hijack the discussion to politics, but I am from Virginia, a swing state this year. Our own Governor, Bob McDonnell is talked about as a possible vice presidential candidate as a ‘safe pick’. He is originally from Fairfax, but is now married to Richmond (a little known fact is that Richmond was the second capital of the Confederacy). Virginia was rock solid Democratic from the ‘30’s New Deal, but by the time Will Shortz attended Virginia, it had become a solid red state until Obama won in 2008. While it is too early for either party to sing the good ole’ song of victory, it will be an interesting season.
I'm hard-pressed to come up with a. clue. They all seem to pale in comparison to the hidden ones above.
Agreed: The easy part was solving the challenge. The hard part is coming up with a hint that doesn't give it away. This could take a while!
SBD: "Give me that old time religion." Is that a dead give away???
Oxygen Iodine Carbon what you did there !!
This is not a very good hint. Or is it?
Frankly, Errudite, yes. It is.
1) Mr. Spatula never laid a hand on this one.
2) Fans of Whitesnake and Twisted Sister probably have this puzzle solved already (of course, that's assuming they listen to Weekend Edition---and, frankly, there's probably a better chance of seeing Mel Gibson star in the remake of Fiddler on the Roof).
I have a sneaking suspicion the symbol is completely different from the element. But I haven't really looked into the puzzle much.
Just figured it out. A bit tricky if you ask me. Hardy har har!
I had a boring chore I finally had to tackle before attempting to solve the puzzle this morning. I’d been putting it off for quite a while and things had really started to pile up.
The first three letters of the person's name spell the first name of a well known fictional character. The second, third and fourth letters of the person's name spell the first name of a semi-well known television personality. I ain't kidding.
Re: the famous person's work - not a fan, yet I was able to solve anyway.
I'm just glad that, unlike last weekend, they didn't have to update the online clue. Switching between the two clues rattled me a little.
I had a rather bad feeling about this puzzle from the start, but I did finally get the answer.
I didn't expect to return to town and find this week's puzzle was a period piece.
I think this entertainer has a solid core of fans, even though I could take or leave his/her particular act.
Jackass Alfredo! Does it usually come with noodles?
I give up. I can't figure this one out.
I have faith that you'll figure it out.
Me neither, Mr. Solo. No good clues on this blog either.
The answer came to me while listening to NPR Sunday morning and putting on my crisply creased trousers for church.
John K., a penny for your thoughts?
Oh well, at least it's a lovely day for drinking. Hot, humid, and unsettled.
I might have to recycle my clue from a couple weeks ago about a particular London landmark.
The Olympic opening ceremony; at the transition to the Industrial Age; the rolling up and removal of grass; was this a mime of a retort aimed at a critic who had the cheek to doubt the quality of the event's organisation?
"I had a rather bad feeling about this puzzle from the start, but I did finally get the answer."
Definition of FEY, "Marked by a foreboding of death or calamity."
I found this puzzle interesting, but I believe it is also flawed. Since I don't watch TV except rarely, I may be mistaken, but I do not think Tina Fey is known for using irony. She is known for satire, parody and sarcasm, but I cannot recall her using irony. When I think of a performer who is known for using irony the name that comes immediately to mind is Steven Wright.
How ironic would that be; to pick Wright and have it be wrong?
TINa FEy worked on SNl with IRONy.
The London Eye is a ferrous wheel.
Such a dark (but accurate) meaning for FEY. I was thinking of the "unconventional, crazy" meaning, to which I attach a sense of lightness or ease, which accounts for the easy solution, and of course finding a proper hint was hard, as IRON.
"This could take a while!" was an oblique reference to the Iron Age.
"I've been trying combinations for a while now. I was under the impression Zinc was an aggregate of minerals. To the contrary, it is part of the transition metals."
Zinc is element number 30, and an aggregate of minerals is also known as a rock. Put them together, and you get 30 Rock, the name of Tina Fey's comedy show on NBC.
The image hint had nothing to do with the image, and everything to do with the string of eight digits in the URL. 22112639 can be split into 22, 11, 26, 39, which when matched with the corresponding elements becomes Titanium, Sodium, Iron, Yttrium. In other words, Ti, Na, Fe, Y. Following this pattern, Blaine's corresponding sequence of digits is 5, 57, 53, 49 - Boron, Lathanum, Iodine, Neon. B La I Ne.
"I'd like to keep up with politics, but... Ugh, I can't stand cable news. Ever try watching for more than five minutes? Talentless idealogues narrating absolutely facile editorials. Yeech. I revile opinion news. (Yes, I'm aware that this is, itself, an opinion.)"
"...Talentless idealogues narrating absolutely Facile editorials. yeech. I revile opinion news. (yes,..."
And finally, an appropriate clip from 30 Rock.
A couple curious Reddit links. indicating this puzzle has been known about for at least eight months.
Jan already pointed out my Ferris/Ferrous pun. My other clues were Solid Core, which referred to Earth's solid core of iron, and faith, which sounds similar to Fey.
And, of course, the Spanish word for faith is .. ?
Will someone please explain how irony is a "main element" of Tina Fey's "work?"
I offered the musical clue of Paul Simon because the singer/songwriter has reportedly hosted SNL more than any other person.
But, in honor of the puzzle, I'm now referring to Pamela Anderson as "SiBreasts"
I don't know where you heard that, but the award for most times hosting SNL goes to Alec Baldwin and coming in second by one is comedian Steve Martin.
Ditto on that. In fact Steve Martin hosted once even though he had a severe head wound from an arrow. Beyond the call of duty.
My clues - "hard-pressed" was reference to ironing; "seem to pale in comparison" - "pale in" was reference to Sarah Palin.
Wayne Newton (Ne-neon) - neon lights of Las Vegas where he does his gigs. . My clue re-"old time religion"= his religious proclivities.
"It's a lovely day for drinking" From the chorus of the musical Candide's song Auto Da Fe.
The show, of course, was Saturday Night Live, which would usually be airing between the two times of my posts (at least on the west coast).
By pointing out that this person used to be a regular on this show, but now besides that it wasn't even on that night (due to the Olympics), I was giving an example of what be considered an irony.
Just did a "find on page".
Right on! How did I ever miss that one?
Waiter! I'll have a large Scotch as it pours, and a gin & sardonic for the lady, if you please. Does that suit you, Tina?
"As it pours" is an interesting phrase; I suppose once the Scotch has been messed up with some foreign substance, there's no way to "neatify" it.
Sorry, but my attention span is not that short.
BTW: You neglected to capitalize the first letter of your sentence along with failing to end with a period. I point this out due to this puzzle being about the Periodic Table.
SDB u need to get out more. try SDMan.
Since u mention it. I began with SDMan, but when I had to switch servers I found it was taken by some usurper. I only wish I could have come up with something unique like say: Unknown.
I have a better suggestion. You bring over some quality wine and I'll supply the horsed-overs and we'll discuss it like groan-ups.


If the Gods of Olympus subscribed to the New York Review of Books, they would surely be laughing hard after reading the unwitting ironies peppering Bill McKibben’s “Green Fantasia” review of Thomas L Friedman’s “Hot, Flat and Crowded: Why We Need a Green Revolution – and How It Can Renew America”.
One wonders if Mr. McKibben will find a way to display less hubris, and more wisdom next time around.
I will focus here on what I see as the two most glaring examples: first of all, about Katrina, the 2005 hurricane that devastated New Orleans and, in the words of Mr McKibben, “woke Friedman from his nap”.
At that point, Mr McKibben (who should have known better) implicity concedes Mr Friedman’s point: making a direct connection between Katrina, and human-induced Climate Change.
[Friedman:] “Have we introduced so much CO2 into nature’s operating system that we no longer know where nature stops and we start in shaping today’s weather”. [McKibben:] Well, indeed we have.
But no serious scientist will confirm that Katrina was caused by (anthropogenic) Climate Change. Within the IPCC itself, the question of “attribution” (how to identify the “signature” of Climate Change in the weather of today, rather than the climate in 15 or 20 years’ time) is still open, and no doubt we will hear more about it in the months leading to the December 2009 Copenhagen Conference.
After all, Katrina was a relatively average Category-3 hurricane when it struck the New Orleans area. And even if 2005 saw a record hurricane season, neither that nor the “duds” of 2006 and 2007 can be used as evidence for or against Climate Change.
In truth, Mr McKibben should have forcefully corrected Mr Friedman on Katrina, as it is extremely unwise to try to solve Climate Change, that he defines as the “most severe of our challenges”, starting from incorrect premises. In fact, by propagating the idea that New Orleans was destroyed by Climate Change, Mr McKibben and Mr Friedman help the real culprits “off the hook”, including the extreme lack of organization in the rescue efforts, of which FEMA’s now-legendary incompetence will forever be indicated as the most damning example.
Another point where Mr McKibben will surely regret his words, concerns “the largest story of the year, and indeed the dominant new trendline of our time”. Dire financial straits for the majority of the world’s economies, perhaps? No: “the sharply rising cost of oil”.
Evidently, Mr McKibben submitted the article long before Lehman Brothers went bust alongside the country of Iceland, before it became normal to hear of hundreds of billions of dollars being handled out to avoid a Depression-Mark II; and before the “cost of oil” sharply stumbled back to below $60 a barrel. No fault there.
The real irony is that Mr McKibben comments that Mr Friedman’s book is “out of date even before it’s published”: that is, exactly what McKibben’s article is. Images of motes and beams spring to mind…also, is it true that “we’re [possibly] starting to run out [of oil]”? Well, yes, it is possible. But as the precipituous fall in oil prices has shown, that was not the reason for barrels to be traded at more than $140 just a few weeks ago.
A final consideration on Mr McKibben’s polemic against Mr Friedman’s “optimism”, “the great imperative of the conventional wisdom”: the alternative to which is alas left unexplored.
Is Bill McKibben advocating “pessimism” by any chance? And what kind of pessimism, one asks? Obviously (or not?) McKibben is not the type to elicit apathy and desperation by advocating a frame of mind where everything we do is useless, because too little, and too late. Therefore: if “Global Warming, above all, should give one pause” (emphasis in the original), what is the next action (if there is any) after that pause has finished?
And so to you Bill McKibben…what would you rather be? “Usually right”, or able to “[make] great changes”?


Is thermal mass a bad thing in cold climates, could this make internal insulation a better option?
General: Is thermal mass a bad thing in cold climates, could this make internal insulation a better option?
So I remember years ago reading that "thermal mass is a good thing, because the heat of the day is soaked up by the thermal mass and regulated out as it gets colder" etc. I remember thinking, I live in Scotland, what heat of the day!! It was obviously written by someone living on the southern edges of the UK, if not somewhere like Arizona.
Thinking about this again today I found this page https://sustainabilityworkshop.autodesk.com/buildings/thermal-mass and the assertion that in hot or cold climates thermal mass might be a bad thing. It made me wonder about mass and thermal conductivity and the impact of internal/external insulation in a typical modern occupancy pattern.
My house has 600mm stone walls, a lot of wood/lime plaster etc, so a fair amount of mass. When the heating is off, say from around 10pm to late afternoon the following day, that mass will be equalising to the temperature outside. Even with some external insulation installed, thats only slowing the transfer of heat, so eventually the walls will cool to the temp outside. Before I get home the heating system then has to come on and heat up that mass before the house will become comfortable, which would normally mean having the heating come on a few hours before getting home. With external insulation, the whole wall has to be heated first before the insulation will have any effect, but with internal insulation the rate of heat transfer would presumably be slowed as soon as it as begun to pass through the plasterboard in front of it?
In such a scenario, is there an argument to say that a wall with a lower u value, could actually be more effective/cheaper to heat? It just seems that the u-value model seems only to consider a steady state. Maybe this is why people seem to notice a benefit from things like sempatap, that on paper don't look very effective.
I just wondered if there had been research or knowledge out there on this, or maybe there are things I haven't considered.
In such a scenario, is there an argument to say that a wall with a lower u value, could actually be more effective/cheaper to heat?
Walls with lower U-value are better insulated, and thus are generally cheaper to heat. Is that what you meant?
If you have a lot of thermal mass inside the insulation then it is generally better to keep the inside at a roughly constant temperature, rather than switch the heating on and off. If you have insulation inside the thermal mass then it makes sense to only heat the building for the time you are there.
There's a lot of research on this topic and there's been a lot of discussion on this forum, among many other places.
As well as the insulation and 'thermal mass' (actually volumetric heat capacity) you also need to think about thermal admittance and suchlike and 'decrement delay'.
Or specific heat capacity as that uses mass as the measure, not volume.
Start by looking up thermal inertia, the formula is pretty simple.
I think you will find that in the UK's relatively mild climate, the mass of the building makes little difference.
One of the problems is that it is very hard to compare 'like for like' or, as in your case, how a 600mm wall of Rockwool would perform.
Posted By: SteamyTea Or specific heat capacity as that uses mass as the measure, not volume.
And as has been discussed in various places over the years, volume is a far more useful basis than mass for this property.
If you type thermal inertia into google, you'll find that it's a subheading in the volumetric heat capacity article in wikipedia. It's more of a material property than a useful way to view wall structures.
The wall structure makes quite a big difference to the best way to heat a house. 600 mm of stone behaves quite differently to a timber frame stuffed with rockwool and a sheet of plasterboard on the inside.
"The ability of materials with a high thermal mass can be exploited to minimise diurnal swings. An example of a very high thermal mass building would be an old stone church. The temperature of the internal space changes marginally on a daily basis and almost not at all diurnally. In dwellings, a high thermal mass can help prevent overheating if the heat stored during the day can be effectively rejected at night. This therefore requires continuous high levels of night-time ventilation, which in some locations may not be practical or desirable (NHBC, 2013).
A low thermal mass building would be a timber framed building with lightweight floors, ceilings and internal walls. The internal structure assumes the temperature of the air very quickly and so has minimal impact in limiting any change in temperature."
The above is in relation to summer overheating, but ties across to heating - as mentioned above, lower thermal mass tends to heat up more quickly, but also cool down more quickly (subject to the more significant effect of insulation of course) - this is more useful for properties requiring a quicker responsiveness; A higher thermal mass property (with good levels of insulation), will suit a continual release lower temperature heating regime more, but would be less responsive.
What I mean by this is that a lot of what is said about old houses and how they behave is based on a very out of date model of occupancy where there was someone there all day with a fire or range going constantly. For lots of people now they leave for work early in the morning and come back in the evening, so quick heat up times are potentially more important than overall u value.
Posted By: djh Walls with lower U-value are better insulated, and thus are generally cheaper to heat. Is that what you meant?
Sorry, I worded that very badly. What I meant was the opposite. Could a wall with a higher u value actually result in less energy use to heat the occupants to comfort levels because heating the room up quickly, but for shorter periods of time.
If I take an extreme example to demonstrate what I am getting at. Say my house has 100mm of EPS on the outside skin. If I was away for a month in January with no heat in the house and then tried to heat the house it would take a long time to heat the mass in those walls before the heat reaches the external insulation. If there was 50mm of EPS on the inside I would expect the room to heat relatively quickly, as it would take longer for the heat energy to reach the walls.
Steamy, djh, Sigaldry, thanks for the terminology. Looked up some of these terms and found a link discussing decrement delay and thermal buffering http://www.greenspec.co.uk/building-design/decrement-delay/ and they give an example where a caravan, and a stone building might have similar u values, but on a sunny day the caravan heats up much more quickly. This is the reverse of my point I suppose, because in Scotland its pretty rare that you are going inside to get away from the heat.
If I am understanding this correctly it sounds like if I want a quick heat up to comfortable room temperature, then its really only the thermal conductivity and specific heat capacity of the interior surface that is the primary concern. If I want to stabilise the interior temperature then density becomes important.
Posted By: Kenny_M Even with some external insulation installed, thats only slowing the transfer of heat, so eventually the walls will cool to the temp outside.
Yes, but it all depends on what you mean by "eventually".
For example, I had a winter holiday of 10 days over xmas-new year: no heating on in the house, no occupancy.
On leaving the house was at 20°C, on returning it was at 16°C. The average external temperature over that period was probably 11 or 12°C (mild winter). Just with 50mm EPS external wall insulation.
I put this down to the windows, and high mass.
At a guess, "eventually" in my case might be, say, 3 months... or not at all, even.
One way to determine the length of the eventuality might be to actually instrument the house with data loggers etc.
Always a good idea and very cheap to do now.
I am knocking up simple 6 sensors loggers for a few quid.
Posted By: SteamyTea I am knocking up simple 6 sensors loggers for a few quid.
Posted By: Kenny_M If I am understanding this correctly it sounds like if I want a quick heat up to comfortable room temperature, then its really only the thermal conductivity and specific heat capacity of the interior surface that is the primary concern. If I want to stabilise the interior temperature then density becomes important.
That's a pretty good article, I think, although I just skimmed it. I don't think it makes sense to separate factors in the way that you have; what matters are the overall properties of the materials. But you're correct that the interior materials matter much more if you're going to vary the internal temperature, whereas if the internal temperature is stable then the materials further out in the wall also becomne relevant.
We seem to be talking about living in insulated boxes.
For me this minimises incidental solar gains so does not work.
I have been shading my windows for the last month -- some friends are still running their heating!
Just to clarify where I am coming from on this. We have a modern extension which is south-ish facing, and is the main cooking/eating/sitting area. I plan over the next year to take a 'normal' approach and insulate externally, triple glaze, and this room would benefit from the thermal mass in the interior to regulate the temp and take advantage of solar gain.
My thoughts in this thread are related to the old part of the house. I can't ever externally insulate the north/front face due to conservation area rules, and while the sides might get approved if I could make a strong enough case, it would be tricky and expensive. That's made me think about how those rooms are used.
For example there is a small room at the front of the house, with one external wall with a window facing north, and the other facing east but in the shadow of the house next door. There is little to no solar gain there. I have projector in there and 2 or 3 evenings a week at most I might go in there to watch a movie. To make that room comfortable I would need to leave the heating on reasonably high all the time, because it takes a long time for the surfaces to heat up.
Even if I was allowed to do it I am not convinced external insulation would benefit me over internal in this scenario, because I would still have to heat the mass in the walls, compared to internal where the heat up time for the internal surface should be much shorter. In a scenario like this I am suggesting that perhaps internally insulated, with say a wall u value of 0.7, might be more energy efficient, than a u value of say 0.3, because its energy required to heat the room for comfort maybe 3 times a week for 3 hours at a time, rather than a steady state scenario.
I also think the impact of solar gain is over stated, perhaps because UK models sometimes presume a location in the southern half of England, not so much sun here during the six month winter!
Posted By: Kenny_M For example there is a small room at the front of the house, with one external wall with a window facing north, and the other facing east but in the shadow of the house next door. There is little to no solar gain there. I have projector in there and 2 or 3 evenings a week at most I might go in there to watch a movie. To make that room comfortable I would need to leave the heating on reasonably high all the time, because it takes a long time for the surfaces to heat up.
That's quite similar to the position in an old church. Two parts to the answer. First, don't think about heating the room, think about heating the occupants, usually by radiant heaters or perhaps by forced air. Secondly, apply internal insulation and in particular a surface finish with low admittance, so it feels warmer faster.
Me to. I want to track temp and RH through several points of my roof makeup I may be able to give comfort to others - my OSB sheathing has only 37% of the insulation value on the outside. but I havent got time to research the hardware/software required for a cheep monitoring solution.
I am planning to fit a stove in this particular room, at the opposite side from the projector screen, so that I get the radiant heat from the stove.


In this case, it seems the sentence is "passing by (somewhere)" or "going past (somewhere)"
For avoir, the examples are = spend <some time>, take <a test or exam> , and pass <something> (to someone), none of which seem to match this sentence.
Can someone please explain why using "avoir" instead of "être" is considered correct in this case?
In this case it is clear that you pass by something ( the door). Grammatically this verb has a direct object so you use 'avoir'.
"Nous sommes passés devant la porte."
"We went past the door..."
The door in this case is not the direct object of passer.
It is just a question of grammar rules.


activities related to the theme of the unit.
have in overcoming these obstacles?
theme of the unit -overcoming obstacles?
• 1. Sports: Sports play an important in American life.
classes to complete their studies.
four years from 776 B.C.
•IN 2008 Beijing will host the 29th Olympic Games.
• The Olympic motto is Citius---Altius---Fortius.
• The ancient Games were sacred events.
plan to revive the Games.
tense to the past perfect tense?
The first sentence of paragraph 6.
• 3. Where does author conclude the text?
Man in America led so simple a life.
what kind of event the pole vault is.
father is a hard-core realist.
He is diligent, perseverant, optimistic, ambitious, etc.
overcome in attaining his goal.
meanings of “ work ”.
Michael's blindness until the last sentence?
How to keep the article smoothly?
make these parts in the text flow smoothly?
the reward for his hard work.
The white shirts were sweated through.
She danced with a grace that surprised us.
She had the grace to say that he was right.
He agreed that he was wrong with bad grace.
She lost the election by a mere 20 votes.
I will win the National lottery.
some children can't tell fantasy from reality.
passion as he always had.
• have a passion for: have a strong interest in sth.
between the two countries have been revealed.
thing is to find a job.
• She does not enjoy the details of housekeeping.
what happened, without going into detail?
were going to say at the meeting.
chance to discuss it in detail.
he will be expelled if this cheating recurs.
is to learn how to relax.
• Massage is used to relax muscles.
me by asking me questions about my studies.
him drink a whole bottle of vodka.
• She was vain of/about her appearance.
15. be ashamed of: feeling foolish or uncomfortable because of sth.
the test that she went and told the teacher.
all of the passengers were getting tense.
the glass to her lips.
stretching their hands out to passers-by.
1.What does “hit sb. like a wet bale of hay” mean?
as a sudden, forceful and unpleasant surprise.
He felt anxious, tense, nervous, etc.
a world record in pole vault?
2) When did you begin to learn English?
4. Where did you come across John?
It was in Central Park that I met John.
was hugging his wife and crying.
Model 2: We know what you said.
process that led to these findings.
• 3) It has been a week of alternate sunshine and rain.
park be built near the community.
6) Nobody believed his claim that he was innocent.
I work out in the gym for one hour every morning.
Florance has worked as a cleaner at the factory for five years.
new products doesn’t work at all.
who don’t know how to learn.
The media began to work one hour after the child took it.
him to set a world record in the pole vault.
who have/ has exerted the greatest influence on me.
office that I met John.
the body along with tears.
him, he began his third life.
• we're planning to install a new shower.
• Ashley installed herself behind her table.
• I began to doubt my own sanity.
• Many people suffered from a great dread of heights.
His wife has suffered from ill health for some years.
• A storm swept over the country.
Cold winds swept over the barren plains.
France jacked up its key bank interest rate.


How rich is Juliette Lewis?
Juliette Lewis is an American actress and vocalist with a net worth of $20 million dollars. Produced in la, California, in 1973, Juliette Lewis is the Oscar-nominated star of the 1991 thriller “Cape Fear”. Juliette made her TV debut in the 1987 show “I Married Dora”, that she was nominated for a Young Artist Award. Lewis’ big break arrived with her 1991 appearance in “Cape Fear”. Lewis was nominated for an Emmy for 2003’s “Hysterical Blindness”.
She’s appeared in music videos, advertisements as well as in the favorite video game “Grand Theft Auto IV” as Juliette. Lewis released her first solo album, “Terra Incognita”, in 2009, after performing with Juliette and the Licks. Musicvideos , break up in 2003. Lewis, who’s a supporter of Little Kids Rock and works to maintain music in low income schools, is an associate of the Church of Scientology.
4 Turned down the role of Mia Thermopolis that eventually went to Anne Hathaway in The Princess Diaries (2001).
5 Friend of Alanis Morissette.
6 Sister-in-law of Ethan Suplee. He is married to her sister Brandy Lewis.
8 She was introduced to her future husband Stephen Berra by her younger sister Brandy Lewis.
9 Although she is now divorced, she remains good friends with her ex-husband, Stephen Berra.
10 Posed for a portrait in US Magazine, by Peggy Sirota, which featured nothing but an extreme close-up of the soles of her bare feet.
11 Fronts a rock band called "Juliette and the Licks" which is touring on Van's Warped Tour in 2004.
12 Auditioned for the role of Lydia Deetz which was played by Winona Ryder in Beetlejuice (1988).
13 Her song from Natural Born Killers (1994) was used in another song, "Bad Brother" by The Infidels.
14 Played a suicidal mental patient in the music video for the Melissa Etheridge song "Come to My Window". Lewis' erratic behavior frightened the director to the point where he yelled "Cut!" several unnecessary times for fear that Lewis had truly suffered a mental/emotional breakdown.
16 Daughter of Geoffrey Lewis and Glenys Batley, a graphic designer.
17 Father almost named her Snow Lake.
18 Drove without driver's license until she was 21. She owned a car bought under a friend's name and had been driving illegally since age 15. Eventually got a license after she got caught not stopping at a stop sign.
20 Dropped out of high school just three weeks after starting.
21 Legally emancipated from her parents at age 14.
22 Sister of Lightfield Lewis and Brandy Lewis. Half-sister of Dierdre Lewis and Matthew Lewis.
1 Just to buck the system in California, I bought a Mazda for $6,000 when I was 15 without even bothering to get a license.
2 Just 'cause I'm in the same age bracket as Johnny Depp and Leonardo DiCaprio doesn't mean we all screw together.
3 Fame can be just so annoying because people are so critical of you. You can't just say "hi". You say hi and people whisper "Man, did you see the way she said Hi. What an attitude."
Kelly & Cal 2014 performer: "Moist Towelette", "Change" / writer: "Moist Towelette", "Change"
Isle of Wight Festival 2010: Live 2010 TV Special performer: "Uh Huh" / writer: "Uh Huh"
Grand Theft Auto IV 2008 Video Game writer: "Inside the Cage David Gilmour Girls remix"
A Deal Is a Deal 2008 writer: "Hot Kiss"
Picture Claire 2001 performer: "Feeling Alright"
The Crow: Salvation 2000 performer: "Bad Brother"
The Other Sister 1999 performer: "Come Rain or Come Shine"
Some Girl 1998 performer: "She Silenced You" / writer: "She Silenced You"
Full Tilt Boogie 1997 Documentary performer: "What's Up"
Strange Days 1995 performer: "Hardly Wait", "Rid of Me"
Natural Born Killers 1994 performer: "These Boots Are Made for Walkin'", "Born Bad"
Is Juliette Lewis's Net Worth Deserved?


The Company today declares a dividend of 1.625 pence per ordinary share payable on 30 July 2018 to shareholders on the register as at the close of business on 21 June 2018 (the record date) and the corresponding ex-dividend date will be 22 June 2018.
The Board has decided to offer shareholders a choice to receive dividends in cash or in shares via scrip dividend. Further details on the scrip dividend alternative will be sent to shareholders in due course.
The LEI number of the Company is 549300ZQIYQVNIZGOW60.
The Company is a registered closed-ended collective investment scheme registered pursuant to the Protection of Investors (Bailiwick of Guernsey) Law, 1987, as amended and the Registered Collective Investment Scheme Rules 2015 issued by the Guernsey Financial Services Commission (''GFSC'').
The Company's investment objective is to provide shareholders with a sustainable and attractive level of dividend income, primarily by way of investment in Credit Assets as defined in the Company's Prospectus.
This announcement contains "forward-looking" statements, beliefs or opinions. These forward-looking statements involve known and unknown risks and uncertainties, many of which are beyond the control of the Company and all of which are based on its directors' current beliefs and expectations about future events. Forward-looking statements are sometimes identified by the use of forward-looking terminology such as "believes", "expects", "may", "will", "could", "should", "shall", "risk", "intends", "estimates", "aims", "plans", "predicts", "projects", "continues", "assumes", "positioned" or "anticipates" or the negative thereof, other variations thereon or comparable terminology, or by discussions of strategy, plans, objectives, goals, future events, assumptions or intentions. These forward-looking statements include all matters that are not historical facts. Forward-looking statements may and often do differ materially from actual results. They appear in a number of places throughout this announcement and include statements regarding the intentions, beliefs or current expectations of the Board or the Company with respect to future events and are subject to risks relating to future events and other risks, uncertainties and assumptions relating to the Company's business concerning, amongst other things, the financial performance, liquidity, prospects, growth and strategies of the Company. These forward-looking statements and other statements contained in this announcement regarding matters that are not historical facts involve predictions. No assurance can be given that such future results will be achieved; actual events or results may differ materially as a result of risks and uncertainties facing the Company. Such risks and uncertainties could cause actual results to vary materially from the future results indicated, expressed or implied in such forward-looking statements. The forward-looking statements contained in this announcement speak only as of the date of this announcement. Nothing in this announcement is, or should be relied on as, a promise or representation as to the future. The Company disclaims any obligation or undertaking to release publicly any updates or revisions to any forward-looking statements contained in this announcement to reflect any change in its expectations or any change in events, conditions or circumstances on which such statements are based unless required to do so by applicable law, the Prospectus Rules, the Listing Rules or the Disclosure Rules and Transparency Rules of the FCA. No statement in this announcement is intended as a forecast or profit estimate.
Neither this announcement nor any copy of it may be made or transmitted into the United States of America (including its territories or possessions, any state of the United States of America and the District of Columbia) (the "United States"), or distributed, directly or indirectly, in the United States or to US Persons (as such term is defined in Regulation S under the US Securities Act of 1933, as amended (the "Securities Act"). Neither this announcement nor any copy of it may be taken or transmitted directly or indirectly into Australia, Canada, Japan or South Africa or to any persons in any of those jurisdictions, except in compliance with applicable securities laws. Any failure to comply with this restriction may constitute a violation of United States, Australian, Canadian, Japanese or South African securities laws. The distribution of this announcement in other jurisdictions may be restricted by law and persons into whose possession this announcement comes should inform themselves about, and observe, any such restrictions. This announcement does not constitute or form part of any offer or invitation to sell or issue, or any solicitation of any offer to purchase or subscribe for securities in the United States, Australia, Canada, Japan or South Africa or in any jurisdiction to whom or in which such offer or solicitation is unlawful.


Two friends are discussing a university lecture on conserving fish. Toby was unable to go to the lecture, so Chris is telling him about it. This extract is from the end of their conversation.
Toby:Well I must say, conserving fish sounds like a really major issue. I had no idea of the scale of the problem. Did they give any advice on what individual people can do to help?
Chris:Er…, yeah. They did actually. At the end of the lecture, they explained some guidelines that shoppers should think about when they buy fish to eat.
Toby:Oh, right. Can you remember what they were?
Chris:Yeah. I made some notes. Hang on. I've got them here. Let me see. Well, the first thing they said is that it's important to buy a variety of different fish.
Chris:Well, if people do that, it takes the pressure of any particular species, like, say, bluefin tuna, which might be endangered.
Toby:Oh, of course. I suppose it protects the whole ecosystem better.
Chris:Yup. The next thing they said was that you shouldn't buy anything which is sold as 'baby fish'.
Toby:Yeah, I've heard that eating smaller fish can destroy whole fish stocks.
Chris:That's right. So anyway, when you do buy fish, make sure they are locally caught. Oh, and another thing, remember to ask the retailer how they were caught.
Toby:What difference does that make?
Chris:Well, some ways of fishing, like trawling, are really destructive to the marine environment. Thousands of fish get caught in the fishing nets and are just thrown away!
Toby:That's terrible. I've read that a lot of the fish we eat now is actually farmed. Did they say anything about that? I mean, farming fish has got to be less damaging to wildlife, hasn't it?
Chris:Not necessarily. Apparently some fish farms are breeding grounds for diseases which can then be passed on to wild fish. This is a particular problem for salmon farms which can produce a lot of parasites. The advice is, if you buy farmed fish, make sure it has been farmed in open sea conditions. They say it's much less likely to spread disease.
Toby:OK. There really is a lot to think about. Is that it?
Chris:There were a couple more points. One is to include herring in your diet. Apparently this stops it from being converted into animal feed.
Chris: But the main thing is, we should all keep up to date with the latest information, and keep asking retailers lots of questions. They say, in the end, consumer concerns lead to action by the suppliers.
Toby:Got it! Now I can enjoy eating fish, and do my bit for the environment.
Variety: The weather in California is great, although there isn't much variety. It's sunny almost every day.
Conservation: Careful conservation of classic architecture is vital if we don't want to lose it forever.
Ecosystem: Coral reefs are one of the most important marine ecosystems on earth. Nearly every kind of organism can be found there.
Breeding ground: Slums are a breeding ground for crime.
Consumer: As a consumer, you have to stand up for your rights. If your new DVD player doesn't work properly, just take it back to the shop.


While practicing writing this sentence fragment (“First you must select a good cookbook, then ...”) in German using each of my two ‘silent tutors’(translate.yandex.ru and translate.google.com) to check the correct way to say or write that fragment I found that the translations returned by my two tutors was functionally the same, but that they had differences in word order and familiarity with the person to whom my sentence fragment might have been directed.
In checking my German, my Russian tutor (Yandex) returned my sentence in ‘polite’ word usage, while my American tutor (Google) used ‘familiar’ word usage. However, you’ll notice that both of my tutors went on to consistently correct my use of the word “Erst” (an adjective) to “Zuerst” (an adverb) whenever I made small revisions to either the English or the German sentences.
(A grammar anomaly indirectly related to my question is in the American version (Google) where “und” is required before the word “dann” -- why, I don’t understand.
My question is this: Since in the ‘Ordinal Numbers’ section in many of my German grammar books (including Duden’s “Die Grammatik”) the word “zuerst” is not mentioned nor defined; the only German grammar book that did mention it was only in the “Wörterverzeichnis” section of my English language grammar book Colloquial German (by P. F. Doring, 1975 edition or later).
So, is the word “zuerst” okay to be used, but okay only in colloquial [i.e., everyday] German speech and writing, and is the “zu” in that word a separable prefix?
First of all (or zuerst): you'll never find zuerst in a list of Ordinal Numbers, because it is not a number.
The foremost usage of zuerst is to sequentielly order things to be done - which is exactly what you wanted to translate. So zuerst is completely correct in both translations (others things are not, but more to that further down).
Zuerst is also used if you want to express an order in time (which also refers to your example, but to a lesser extent), like e.g. "zuerst eroberten die Römer die Kleinstaaten auf der italienischen Halbinsel, danach dann die übrigen Völker Europas" (I don't know if that is historically correct, btw).
And finally zuerst may also be used with the meaning of erst.
So, to summarize it, and also answer your questions: Using zuerst in this context is completely OK and is not in any way just colloquial speech. The zu in zuerst is - to my knowledge - not a prefix of erst; rather zuerst is a word of its own.
Now to the other mistakes both your tutors have made: Your first tutor (Yandex) seems to have problems with the order of phrases in german. The sentence "Zuerst müssen Sie wählen ein gutes Kochbuch, ..." (I assume the double word Sie in your example was a typo from your side - otherwise this would be a different error) is completely wrong. Google does a much better job here. On the other hand did Yandex choose the correct form of familiarity. As this sentence seems to be addressed to an unknown audience you would never use Du, but always use Sie.
Finally - the use of und (or here und dann) as in the Google translation or the use of a two comma separated independent clauses as in the Yandex translation is interchangeable.
The meaning of zuerst slightly differs from erst in that, by the prefix "zu-", additional information is given. It thus has a more absolute meaning than a simple erst (cf. English first and at first). I'll give an example at the end of this answer.
Hence, neither is zuerst limited to colloquial speech, nor is "zu-" separable under any circumstances.
Wenn er nach Hause kommt, schaltet er zuerst den Fernseher an.
In this sentence, it is clearly stated that the very first thing he does after coming home is to turn on the TV.
I have no idea which Duden you searched, but "zuerst" is a perfect german adverb and in no way colloquial at all.
It is possible and correct to use the verb "wählen" hier, but a german speaker would rather not use it and stick with "auswählen" in that sentence.
If you address the reader with "Du" or "Sie" depends on context and your chosen style.
Regarding comma or und: that is absolutely up to you and depends on your preference. Both mean exactly the same, it is just a matter of style and surrounding text, if the sentence sounds better with or without the "und".
Not the answer you're looking for? Browse other questions tagged english-to-german adverbs conjunctions colloquial prefixes or ask your own question.
What's with the placement of “aber” here?


Is schedul2.exe safe or is this malware?
This program is located at "C:\Program Files\Common Files\Acronis\Schedule2\schedul2.exe"
Be aware that many tasks will be similiar names to existing tasks or processes. You can always view the running tasks on your computer by pressing ctrl-alt-del to view the windows "task manager", and then view the "processes" tab. This will show you all tasks running or currently active on your PC. Although this shows you all running tasks, it does not show dll file thats are loaded, as they get loaded as part of other processes. Many spyware writers attempt to hide their files on your computer, for example, schedul2.exe may be intentionally misspelled to look like a similiar task, or spyware may be named very similiar to a Windows system task. The reason they do this is so you cannot easily recognize the name in your tasklist as I have mentioned above. Make sure always check the location of the file if you are concerned. You can always find the location of schedul2.exe on your computer by using your Windows search options, but I will also try to list the file location of every file described on this website, so you can verify the correct location. You can view the entire tasklist directory with the link below.


The vast majority of Israeli citizens oppose the settler movement. Despite this, the colonialists recently launched a campaign to lure Israelis to visit the West Bank, the Jewish Forward newspaper reported. "Some 1,000 billboards have gone up across the country, showing photographs of cherubic settler children dressed in biblical costumes and carrying the slogan 'Judea and Samaria - the story of every Jew'."
How did Israel get to this point? Decades of funding and indulging the settler movement have resulted in the current crisis. As Gideon Levy writes in Haaretz: "Every class and institution of Israeli society defends the settlements, finances them from its own pockets, and is a full partner in the [land] theft, even if some of them are disgusted by it."
The West Bank has become a Hobbesian land. Barely a day goes by without yet another report of settlers and the IDF impeding the daily lives of Palestinians on the "disputed" land.
The September pipe bombing by Jewish radicals of Israeli historian Ze'ev Sternhell's home in Jerusalem - a long-time critic of the settler movement - signalled a profound shift in the struggle against Israel's internal enemies, a point powerfully made by leading peace activist Uri Avnery. "Israeli fascism is alive and kicking", Avnery warned."It is growing in the flowerbed that produced the various religious-nationalist underground groups of the past." And yet the vast majority of the international Jewish Diaspora is tellingly silent on these issues, preferring to protest against Hamas "terrorism" and Iranian "provocation". Thankfully Haaretz is unafraid to editorialise on the failure of Israel to uphold its own laws when broken.
Sternhell, even more determined to warn the world against the Jewish state's threats, has argued since the attack against him and his family that "If Israeli society is unable to muster the courage necessary to put an end to the settlements, the settlements will put an end to the state of the Jews and will turn it into a bi-national state".
As a believer in this solution, I don't fear Sternhell's thesis, but settler violence undoubtedly threatens the (long-discredited) claim that Israel is a Jewish democracy.
The UN's special rapporteur on human rights in the occupied territories reported last month that Israel's occupation of East Jerusalem, the West Bank and, until 2005, the Gaza Strip represented elements of colonialism and apartheid. Despite the current truce between Israel and Hamas, the Palestinian Centre for Human Rights found that 68 children had been killed in Gaza in the 12 months to June this year because of "disproportionate and excessive lethal force" by the IDF.
The settler militants are one of the leading impediments to peace in the region yet much of the mainstream media and Zionist leadership remain in denial. The Jerusalem Post editorialised last month that "radical" settlers were "undermining the case for Jewish rights in the West Bank... and harden hearts to Israel's legitimate security concerns and historic civilisational ties to the land." International law is clear: every settlement beyond the 1967 Green Line is illegal and must be removed. There can be no lasting peace and justice without this.
It was a point equally ignored by one of America's leading Zionist leaders, Morton Klein, who wrote recently that, "it is simply a flat-earth statement to describe Judea, Samaria and Gaza as occupied".