bluuebunny/crossref_metadata_2025 huggingface dataset:
Angular momentum and overshooting: two as yet unsolved problems in stellar mixing
Authors: Canuto V. M. , Cheng Y.
Published: October 2008

Helioseismological data have given us two interesting results: the differential-to-uniform solar rotation curve and the extent of the overshooting region (OV). As of today, no model (including numerical simulations) has been able to reproduce these findings. Here, we first present a new model for the angular momentum. It contains new terms representing vorticity and buoyancy that were left out in all previous formulations without a clear justification. It is shown that they extract angular momentum from the stellar core, a welcome feature since the standard angular momentum equation leads to a rotation curve that is considerably higher than what is observed. As for the overshooting extent, all models yield values that are an order of magnitude larger than the helio data of 0.07Hp. We propose a criterion whose main ingredient is a new flux conservation law that includes new terms, one of which increases the dissipation in the radiative zone and thus lowers the OV extent, a tendency in the desired direction. Since we have not coupled the new models to a solar structure-evolution code, we cannot at this stage carry out a comparison with the helio data. The purpose is to exhibit the fact that in both cases the missing ingredients are of such nature as to improve the previous model predictions. A proper quantification remains to be done.
On the boundaries of a convective zone and the extent of overshooting
Authors: Deng L. , Xiong D. R.
Published: October 2008

In this work, we will show that a proper definition of the boundary of a convective zone should be the place where the convective energy flux (i.e. the correlation of turbulent velocity and temperature) changes its sign. Therefore, it is convectively unstable region when the flux is positive, and it is convective overshooting zone when the flux becomes negative. In our nonlocal convection theory, convection is already sub-adiabatic (∇ < ∇ad) far before reaching the unstable boundary; while in the overshooting zone below the convective zone, convection is sub-adiabatic and super-radiative (∇rad < ∇ < ∇ad). The transition between the adiabatic temperature gradient and the radiative one is continuous and smooth instead of a sudden switch. In the unstable zone, the temperature gradient is approaching radiative rather than going to adiabatic. The distance of convective overshooting is different for different physical quantities. The overshooting distance in the context of stellar evolution, measured by the extent of mixing of stellar matter, should be more extended than that of other physical quantities. It is estimated as large as 0.25–1.7 Hp depending on the evolutionary timescale.
The evolution of ‘the moment of inertia’ of stars
Authors: Kim Y.-C. , Barnes S.
Published: October 2008

Observations of the rotation periods of cool open cluster stars display a distinctive dichotomy when plotted against stellar mass/color. Other measures of stellar activity are also known to be dependent on stellar mass and structure, especially the onset and characteristics of convection zones. One proposal for understanding the observed rotation period dichotomy suggested dependencies on the moment of inertia of either the whole star or that of only the outer convection zone (Barnes 2003).

The moment of inertia of stars with the mass between 0.1Msun and 3.0Msun have been calculated using a version of Yale Stellar evolution code (aka YREC). Each star has been evolved from stellar birthline to the onset of the core He burning. For easy comparison to observations, we have calculated the isochrones of these quantities as well as the convective turnover time, of interest to the activity community.
Solar scandium abundance
Authors: Zhang H. W. , Gehren T. , Zhao G.
Published: October 2008

We investigate the formation of neutral and singly ionized scandium lines in the solar photospheres. Extensive statistical equilibrium calculations were carried out for a model atom, which comprises 92 terms for Sc I and 79 for Sc II. Synthetic line profiles calculated from the level populations according to the NLTE departure coefficients were compared with the observed solar spectral atlas. Abundance determinations using the ODF model lead to a solar Sc abundance of between log ϵ⊙ = 3.07 and 3.13, depending on the choice of f values.
Helio- and asteroseismology
Authors: Christensen-Dalsgaard Jørgen
Published: October 2008

Observations of solar and stellar oscillations are providing detailed information about stellar interiors. In the case of the Sun the set of observed frequencies is sufficiently detailed and accurate that the properties of the solar interior, such as sound speed, density and internal rotation, can be inferred with substantial precision and resolution. This allows detailed tests of solar modelling, with interesting and to some extent controversial results. Observations of solar-like oscillations in distant stars have started only recently, owing their very small amplitudes. However, developments in ground-based equipment and observations from space are revolutionizing this field, promising greatly increased insight into the structure and evolution of the stars.
Rate of change of the pulsation periods in the PG 1159 star PG 0122+200
Authors: Vauclair G. , Fu J.-N. , Solheim J.-E. , Kim S.-L. , Chevreton M. , Dolez N. , Chen L. , Wood M. A. , Silver I. M.
Published: October 2008

The pre-white dwarf pulsators of PG 1159 type, or GW Virginis variable stars, are in a phase of rapid evolution towards the white dwarf cooling sequence. The rate of change of their nonradial g-mode frequencies can be measured on a reasonably short time scale. From a theoretical point of view, it was expected that one could derive the rate of cooling of the stellar core from such measurements. At the cool end of the GW Virginis instability strip, it is predicted that the neutrinos flux dominates the cooling. PG 0122+200 which defines the red edge of the instability strip is in principle a good candidate to check this prediction. It has been followed-up through multisite photometric campaigns for about fifteen years. We report here the first determination of the rate of change of its 7 largest amplitude frequencies. We find that the amplitudes of the frequency variations are one to two orders of magnitude larger than predicted by theoretical models based on the assumption that these variations are uniquely caused by cooling. The time scales of the variations are much shorter than the ones expected from a neutrino dominated core cooling. These results point to the existence of other mechanisms responsible for the frequency variability. We discuss the role of nonlinearities as one possible mechanism.
Dust-driven Winds Beyond Spherical Symmetry
Authors: Woitke Peter
Published: October 2008

New 2D dynamical models for the winds of AGB stars are presented which include hydrodynamics with radiation pressure on dust, equilibrium chemistry, time-dependent dust formation theory, and coupled frequency-dependent Monte Carlo radiative transfer. The simulations reveal a much more complicated picture of the dust formation and wind acceleration as compared to 1D spherical wind models. Triggered by non-spherical pulsations or large-scale convective motions, dust forms event-like in the cooler regions above the stellar surface which are temporarily less illuminated, followed by the radial ejection of dust arcs and clumps. These simulations can possibly explain recent high angular resolution interferometric IR observations of red giants, which show an often non-symmetric and highly time-variable innermost dust formation and wind acceleration zone. The dependence of the mass-loss rates on stellar parameters is less threshold-like as used from 1D models, and therefore, it seems quite possible that the phenomenon of dust-driven winds may occur also in less evolved red giants.
On MHD rotational transport, instabilities and dynamo action in stellar radiation zones
Authors: Mathis S. , Zahn J.-P. , Brun A.-S.
Published: October 2008

Magnetic field is an essential dynamical process in stellar radiation zones. Moreover, it has been suggested that a dynamo action, sustained by a MHD instability which affects the toroidal axisymmetric magnetic field, could lead to a strong transport of angular momentum and of chemicals in such regions. Here, we recall the different magnetic transport and mixing processes in radiative regions. Next, we show that the dynamo cannot operate as described by Spruit (2002) and recall the condition required to close the dynamo loop. We perform high-resolution 3D simulations with the ASH code, where we observe indeed the MHD instability, but where we do not detect any dynamo action, contrary to J. Braithwaite (2006). We conclude on the picture we get for magnetic transport mechanisms in radiation zones and the associated consequences for stellar evolution.
Mass loss from pulsating cool stars
Authors: Wang Qian , Willson Lee Anne , Kawaler Steven
Published: October 2008

It has long been clear that most, if not all, of the mass loss experienced by stars from 0.8 to 8 solar masses occurs near the tip of the AGB and/or the RGB. Evolutionary studies have incorporated empirical mass loss laws but theoretical models suggest quite different dependence of mass loss rate on stellar parameters. We are combining evolutionary model calculations with ISUEVO with mass loss modeling using the Bowen code in a systematic study of final stages of stellar evolution. We mapped the RGB (without steady mass loss) to the “Death Zone” as a function of mixing length, mass, and metallicity. We compared these results with observation data from Origlia. We are investigating a possible mass loss mechanism through companions as a complement to mass loss through pulsation. By the end of the project we expect to provide a reliable prescription for AGB mass loss.
The Variability Of RSG : HV2576
Authors: Yang Ming , Jiang B. W.
Published: October 2008

The Harvard Variable HV2576, as a red supergiant in the Large Magallanic Cloud, has a complex light variation, which is not explained well. The existing one-period non-linear pulsation model deviated clearly from its light curve. We tried to fit the light curve by a superposition of several harmonic pulsations. By using the PDM, PERIOD04 and SparSpec codes to analyze the light variation, two periods with 525 and 261 days are well established. Furthermore, the 261-day period is found to change according to the wavelet analysis. In addition, the noise obeying the 1/f law. Based on all these facts, we suggest that the light variation of HV2576 may be due to huge convection cells that interplay with oscillation or the third very long period.
Interaction of massive stars with their surroundings
Authors: Hensler Gerhard
Published: October 2008

Due to their short lifetimes but their enormous energy release in all stages of their lives massive stars are the major engines for the comic matter circuit. They affect not only their close environment but are also responsible to drive mass flows on galactic scales. Recent 2D models of radiation-driven and wind-blown Hii regions are summarized which explore the impact of massive stars to the interstellar medium but find surprisingly small energy transfer efficiencies while an observable Carbon self-enrichment in the Wolf-Rayet phase is detected in the warm ionized gas. Finally, the focus is set on state-of-the-art modelling of Hii regions and its present weaknesses with respect to uncertainties and simplifications but on a perspective of the requested art of their modelling in the 21st century.
Two-fluid models for the winds of OB stars
Authors: Guo J. H.
Published: October 2008

A two-fluid model to OB stars is investigated, in which the flow is described by a set of two components, One for the dense clumps and the other for the smooth gas. The two components are coupled by friction drag. The velocity structure of clumps is assumed to be beta law, thus, the velocity structure of the second component could be attained by shooting method. The result is compared with the X-ray observations.
Binary Evolutionary Models
Authors: Han Z. , Podsiadlowski Ph.
Published: October 2008

In this talk, we present the general principles of binary evolution and give two examples. The first example is the formation of subdwarf B stars (sdBs) and their application to the long-standing problem of ultraviolet excess (also known as UV-upturn) in elliptical galaxies. The second is for the progenitors of type Ia supernovae (SNe Ia). We discuss the main binary interactions, i.e., stable Roche lobe overflow (RLOF) and common envelope (CE) evolution, and show evolutionary channels leading to the formation of various binary-related objects. In the first example, we show that the binary model of sdB stars of Han et al. (2002, 2003) can reproduce field sdB stars and their counterparts, extreme horizontal branch (EHB) stars, in globular clusters. By applying the binary model to the study of evolutionary population synthesis, we have obtained an “a priori” model for the UV-upturn of elliptical galaxies and showed that the UV-upturn is most likely resulted from binary interactions. This has major implications for understanding the evolution of the UV excess and elliptical galaxies in general. In the second example, we introduce the single degenerate channel and the double degenerate channel for the progenitors of SNe Ia. We give the birth rates and delay time distributions for each channel and the distributions of companion stars at the moment of SN explosion for the single degenerate channel, which would help to search for the remnant companion stars observationally.
The role of binary stars in stellar population synthesis
Authors: Li Zhongmu , Han Zhanwen
Published: October 2008

More than about 50% stars are in binaries, but the effects of binary evolution were not taken into account in most previous stellar population synthesis studies. In fact, binaries can affect the integrated peculiarities such as spectral energy distributions (SEDs), colours, and line-strength indices of populations. With the effects of binary stars taken into account, some new results for stellar population studies will be shown. We discuss how binaries affect the colours and Lick indices of simple stellar populations, and the measurement of stellar ages and metallicities.
Evolutionary scenario for W UMa-type stars
Authors: Stepień K. , Gazeas K.
Published: October 2008

An alternative to TRO model of a W UMa-type star is presented in which the binary is past mass exchange with mass ratio reversal. The secondary is hydrogen depleted and both components are in thermal equilibrium. Evolution in contact is driven by orbital angular momentum loss and mass transfer from the secondary to primary component, similarly as it is observed in Algols. Temperature equalization of both components results from an assumed energy transfer by a large scale flow encircling the whole system in the common envelope.
Secular period decreasing of 17 detached chromospherically active binaries
Authors: Luo C. Q. , Luo Y. P. , Zhang X. B. , Deng L. C. , Luo Z. Q. , Yang S. Z.
Published: October 2008

The long-term orbital period changes of detached chromospheric active binaries were surveyed. 17 of such systems are found to be undergoing secular period decreasing with the rates (dP/dt) of −3.05 × 10−9 to −3.77 × 10−5 days per year. The longer the orbital period, the more rapidly the period decreases. Following Stepien (1995), the period decreasing rate due to the angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison shows that the observed dP/dt's are obviously higher than that of the theoretical predictions by 1-3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in close binaries.
Shear Driven Turbulence and Coherent Structures in Solar Surface Simulations
Authors: Kupka F.
Published: October 2008

Numerical simulations of convection near the solar surface are now advanced enough to reproduce both a large set of observational data and provide tests for convection models. We discuss the role of coherent structures in models of solar p-mode excitation, for which the analysis of numerical simulations has provided key inputs in the modelling. The robustness of these simulations is shown by a comparison illustrating the influence of boundary conditions on ensemble averaged quantities. In a concluding example advanced high resolution simulations are shown to resolve the onset of shear driven turbulence generated by up- and downflow structures.
The electric currents from viscosity in differentially moved plasma
Authors: Yang Zhiliang , Wang Hongbin
Published: October 2008

From the two-fluid plasma theory, we derived a kind of current in differentially moved plasma. The current is from the different viscosities between electrons and ions. The higher temperature and lighter mass of the electrons make the viscosity of electrons much stronger than ions. In this way, the electrons will have smaller velocity than ions in the differentially moved layer and contribute a net current in the plasma. The value of the current depends on the temperature and density of electrons in the plasma and the differential velocity ∇2v.
Preconditions of Voluntary Tax Compliance
Authors: Hofmann Eva , Hoelzl Erik , Kirchler Erich
Published: October 2008

Taxpayers’ willingness to cooperate with the state and its institutions, in general, and their willingness to pay taxes, in particular, depend on a variety of variables. While economists stress the relevance of external variables such as tax rate, income, and probability of audits and severity of fines, psychological research shows that internal variables are of similar importance. We present a comprehensive review on the relevance of citizens’ knowledge of tax law, their attitudes toward the government and taxation, personal norms, perceived social norms and fairness, as well as motivational tendencies to comply, and discuss possibilities for strategic intervention to increase tax compliance.
A Quick Visual Mind Can be a Slow Auditory Mind
Authors: Martens Sander , Johnson Addie , Bolle Martje , Borst Jelmer
Published: October 2008

The human mind is severely limited in processing concurrent information at a conscious level of awareness. These temporal restrictions are clearly reflected in the attentional blink (AB), a deficit in reporting the second of two targets when it occurs 200–500 ms after the first. However, we recently reported that some individuals do not show a visual AB, and presented psychophysiological evidence that target processing differs between “blinkers” and “nonblinkers”. Here, we present evidence that visual nonblinkers do show an auditory AB, which suggests that a major source of attentional restriction as reflected in the AB is likely to be modality-specific. In Experiment 3, we show that when the difficulty in identifying visual targets is increased, nonblinkers continue to show little or no visual AB, suggesting that the presence of an AB in the auditory but not in the visual modality is not due to a difference in task difficulty.
Onset of Overweight in Nuuk, Greenland: A Retrospective Cohort Study of Children From 1973 to 1992
Authors: Schnohr Christina W. , Petersen Jørgen H. , Niclasen Birgit V.‐L.
Published: October 2008

The purpose of the study was to examine the age at onset of overweight and obesity of 2–15‐year‐old children in Nuuk, Greenland, born between 1973 and 1992. The study was a retrospective cohort study. The data were retrieved from the children's individual health files containing information on height and weight, and the database contained a total of 12,002 measurements of BMI in 3,094 children (1,522 boys and 1,572 girls). The main outcome measure was age at onset of overweight—the age at which BMI was above an internationally recommended cutoff point for overweight. The study showed that an increasing proportion of children reached the overweight state and did so at an earlier age for later cohorts. This was seen for both boys and girls. Overweight was less prevalent among boys in all cohorts. For the 1973–1992 cohorts of children from Nuuk, Greenland, the age at onset of overweight was significantly decreased.
Weight loss and the Effect on Stature in Children During a Residential Intervention Program
Authors: Larnkjær Anni , Høj Anja R. , Bendtsen Karen M. , Mølgaard Christian , Michaelsen Kim F.
Published: October 2008

Weight loss is generally high in residential weight‐loss programs but the effect of a large weight loss on linear growth is not known. We report the weight loss and the influence on linear growth in a large group of children during a residential weight‐loss program focusing on nutrition and physical activity. In a longitudinal noncontrolled intervention study of 990 overweight children (540 girls) attending the weight reduction program from 1990 to 2001 for about 11 weeks (age: 10–14 years, mean BMI‐standard deviation score (SDS) at enrollment: 2.83) weight and height were measured initially and after end of treatment. Weekly measurements of height and weight were performed on 138 children. The children lost on average 9.4 kg, reduced their BMI by 4.5 kg/m2 and BMI‐SDS by 0.98. In a multiple regression analysis (P ≤ 0.001) weight loss was higher in boys than girls (1.7 kg), higher if the weight was higher at admission (−0.192 kg/kg at baseline) and was positively associated with duration of stay (−80 g/day). Initially the boys' BMI‐SDS was higher than the girls' BMI‐SDS (P ≤ 0.05) but after 8 weeks of treatment the boys had lower BMI‐SDS than the girls. There was no negative effect on linear growth during the treatment; on the contrary, linear growth accelerated during the stay as the average increase in height was 2.38 cm corresponding to 11.4 cm/year. In conclusion the children lost close to 1 kg/week during the stay without any negative effect on linear growth. The cause of the linear growth acceleration needs further investigation.
Extracellular Ca2+ transients affect poly-(R)-3-hydroxybutyrate regulation by the AtoS-AtoC system in Escherichia coli
Authors: Theodorou Marina C. , Tiligada Ekaterini , Kyriakidis Dimitrios A.
Published: October 2008

Escherichia coli is exposed to wide extracellular concentrations of Ca2+, whereas the cytosolic levels of the ion are subject to stringent control and are implicated in many physiological functions. The present study shows that extracellular Ca2+ controls cPHB [complexed poly-(R)-3-hydroxybutyrate] biosynthesis through the AtoS-AtoC two-component system. Maximal cPHB accumulation was observed at higher [Ca2+]e (extracellular Ca2+ concentration) in AtoS-AtoC-expressing E. coli compared with their ΔatoSC counterparts, in both cytosolic and membrane fractions. The reversal of EGTA-mediated down-regulation of cPHB biosynthesis by the addition of Ca2+ and Mg2+ was under the control of the AtoS-AtoC system. Moreover, the Ca2+-channel blocker verapamil reduced total and membrane-bound cPHB levels, the inhibitory effect being circumvented by Ca2+ addition only in atoSC+ bacteria. Histamine and compound 48/80 affected cPHB accumulation in a [Ca2+]e-dependent manner directed by the AtoS-AtoC system. In conclusion, these data provide evidence for the involvement of external Ca2+ on cPHB synthesis regulated by the AtoS-AtoC two-component system, thus linking Ca2+ with a signal transduction system, most probably through a transporter.
Photorefractivity in a polymeric composite photosensitized with NiS nanocrystals
Authors: Fears Tyler M. , Anderson Charles , Winiarz Jeffrey G.
Published: October 2008

The photorefractive performance of a polymeric composite photosensitized through the inclusion of NiS nanocrystals is described. The nanocrystals were characterized using visible-absorption spectroscopy, energy-dispersive x-ray spectroscopy, and transmission electron microscopy. We further demonstrate the ability to enhance various aspects of the composite’s photorefractive performance by performing ligand exchange on the nanocrystals prior to their incorporation into the polymer composite. This procedure resulted in a lowering of the overmodulation voltage from ∼70to∼50V∕μm without affecting the maximum diffraction efficiency of ∼40%. An increase in the two-beam-coupling gain coefficient was similarly observed, increasing from 38to79cm−1. The photoconductivities were used in determining the overall quantum efficiencies associated with the photorefractive devices. All experiments were conducted at 633nm and the data represent a significant improvement in the photorefractive performance of inorganic-organic hybrid photorefractive materials.
Material and electrical properties of HfxRuy and HfxRuyNz metals as gate electrodes for p-metal oxide semiconductor field effect transistor devices
Authors: Sawkar-Mathur Monica , Chang Jane P.
Published: October 2008

Material and electrical characterizations of sputter-deposited HfxRuy and HfxRuyNz gate electrodes atop atomic layer deposited HfO2 were performed with a focus on optimizing their compositions for suitable applications in p-metal oxide semiconductor field effect transistors (pMOSFETs), since Fermi level pinning is a more severe issue for higher work function metals. The alloys of HfxRuy with effective work functions (EWFs) ranging from 4.4 to 5.0 eV were achieved when the Ru metal ratio was varied from 53% to 74%. Nitrided hafnium ruthenium alloys, HfxRuyNz (0%–25% N), with EWFs of 4.9–5.2 eV were also synthesized. Among these materials, Hf0.26Ru0.74 and Hf0.05Ru0.77N0.18 were determined to have EWFs adequate for pMOSFET devices of 5.0 and 5.2 eV, respectively. The slightly higher than expected EWFs of these metal gates are attributed to the presence of oxygen. The depth profiling of the as-deposited gate stacks showed reasonably sharp interfaces between the gate electrode and the gate dielectric with the HfxRuy alloy exhibiting better interfacial properties. Upon annealing, the HfxRuy alloys were found to be more stable than the HfxRuyNz alloys on HfO2.
Instabilities during the growth of dust successive generations in silane-based plasmas
Authors: Cavarroc Marjorie , Mikikian Maxime , Tessier Yves , Boufendi Laïfa
Published: October 2008

Dust growth in silane-based plasmas is known to be a cyclic phenomenon as long as silane is provided. This continuous dust growth leads to an unstable behavior of the complex plasma, characterized by well-defined instabilities. In this paper, a complete study of these instabilities is presented. The electrical analysis is corroborated by an optical one, and high speed video imaging is used to get an insight in the dust cloud behavior. A possible cause of this instability phenomenon is also discussed.
Asymmetric switching in a ferrielectric liquid crystal device
Authors: Jaradat S. , Brimicombe P. D. , Roberts N. W. , Southern C. , Gleeson H. F.
Published: October 2008

The fast multistate switching associated with ferroelectric and antiferroelectric smectic liquid crystals makes them important materials for electro-optic devices, and asymmetric electro-optic responses are of particular interest for some analog switching applications. We report intrinsic asymmetric switching in a ferrielectric liquid crystal device observed using time-resolved small angle x-ray scattering and electro-optic measurements. The experiments reveal a marked variation in the response time depending on field polarity not present in the ferroelectric or antiferroelectric phase. We suggest that this is a consequence of the ferrielectric structure itself and interactions with the device surfaces.
On Harnack’s theorem and extensions: A geometric proof and applications
Authors: Costa Antonio , Parlier Hugo
Published: October 2008

Harnack’s theorem states that the fixed points of an orientation reversing involution of a compact orientable surface of genus

g
g

are a set of

k
k

disjoint simple closed geodesic where

0
≤
k
≤
g
+
1

0\leq k\leq g+1

. The first goal of this article is to give a purely geometric, complete and self-contained proof of this fact. In the case where the fixed curves of the involution do not separate the surface, we prove an extension of this theorem, by exhibiting the existence of auxiliary invariant curves with interesting properties. Although this type of extension is well known (see, for instance, Comment. Math. Helv. 57(4): 603–626 (1982) and Transl. Math. Monogr., vol. 225, Amer. Math. Soc., Providence, RI, 2004), our method also extends the theorem in the case where the surface has boundary. As a byproduct, we obtain a geometric method on how to obtain these auxiliary curves. As a consequence of these constructions, we obtain results concerning presentations of Non-Euclidean crystallographic groups and a new proof of a result on the set of points corresponding to real algebraic curves in the compactification of the Moduli space of complex curves of genus

g
g

,

M

g

¯

\overline {\mathcal {M}_{g}}

. More concretely, we establish that given two real curves there is a path in

M

g

¯

\overline {\mathcal {M}_{g}}

which passes through at most two singular curves, a result of M. Seppälä (Ann. Sci. École Norm. Sup. (4), 24(5), 519–544 (1991)).
Modulation of Rac1 Activity by ADMA/DDAH Regulates Pulmonary Endothelial Barrier Function
Authors: Wojciak-Stothard Beata , Torondel Belen , Zhao Lan , Renné Thomas , Leiper James M.
Published: October 2008

Endogenously produced nitric oxide synthase inhibitor, asymmetric methylarginine (ADMA) is associated with vascular dysfunction and endothelial leakage. We studied the role of ADMA, and the enzymes metabolizing it, dimethylarginine dimethylaminohydrolases (DDAH) in the regulation of endothelial barrier function in pulmonary macrovascular and microvascular cells in vitro and in lungs of genetically modified heterozygous DDAHI knockout mice in vivo. We show that ADMA increases pulmonary endothelial permeability in vitro and in in vivo and that this effect is mediated by nitric oxide (NO) acting via protein kinase G (PKG) and independent of reactive oxygen species formation. ADMA-induced remodeling of actin cytoskeleton and intercellular adherens junctions results from a decrease in PKG-mediated phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and a subsequent down-regulation of Rac1 activity. The effects of ADMA on endothelial permeability, Rac1 activation and VASP phosphorylation are prevented by overexpression of active DDAHI and DDAHII, whereas inactive DDAH mutants have no effect. These findings demonstrate for the first time that ADMA metabolism critically determines pulmonary endothelial barrier function by modulating Rac1-mediated remodeling of the actin cytoskeleton and intercellular junctions.
Reconstructing tumor-wise protein expression in tissue microarray studies using a Bayesian cell mixture model
Authors: Shen Ronglai , Taylor Jeremy M. G. , Ghosh Debashis
Published: October 2008

Motivation: Tissue microarrays (TMAs) quantify tissue-specific protein expression of cancer biomarkers via high-density immuno-histochemical staining assays. Standard analysis approach estimates a sample mean expression in the tumor, ignoring the complex tissue-specific staining patterns observed on tissue arrays.

Methods: In this article, a cell mixture model (CMM) is proposed to reconstruct tumor expression patterns in TMA experiments. The concept is to assemble the whole-tumor expression pattern by aggregating over the subpopulation of tissue specimens sampled by needle biopsies. The expression pattern in each individual tissue element is assumed to be a zero-augmented Gamma distribution to assimilate the non-staining areas and the staining areas. A hierarchical Bayes model is imposed to borrow strength across tissue specimens and across tumors. A joint model is presented to link the CMM expression model with a survival model for censored failure time observations. The implementation involves imputation steps within each Markov chain Monte Carlo iteration and Monte Carlo integration technique.

Results: The model-based approach provides estimates for various tumor expression characteristics including the percentage of staining, mean intensity of staining and a composite meanstaining to associate with patient survival outcome.

Availability: R package to fit CMM model is available at http://www.mskcc.org/mskcc/html/85130.cfm

Contact:  shenr@mskcc.org

Supplementary information:  Supplementary data are available at Bioinformatics online.
Does the reaction of abstaining smokers to the smell of other people's cigarettes predict relapse?
Authors: McRobbie Hayden , Hajek Peter , Locker Joanne
Published: October 2008

Aims  Recent ex‐smokers report a range of reactions to other people's cigarette smoke. We examined the hypothesis that those who find the smell of smoke pleasant and tempting are more likely to relapse than those who have a neutral or even negative reaction to it.

Design  A total of 1110 consecutive patients who attended for smoking cessation treatment and achieved at least 1 week of validated abstinence provided weekly ratings of their reactions to other people's cigarette smoke together with routine baseline measures and weekly ratings of withdrawal discomfort [measured on the Mood and Physical Symptom Scale (MPPS)].

Findings  Twenty‐three per cent of the sample found the smell of other people's cigarette smoke during their first week of abstinence pleasant, and 54% found it tempting. There was only a modest correlation between the two variables. Finding the smoke pleasant was not related to smoking status in the following week, but finding the smoke tempting predicted relapse. Ratings of temptation were related to the severity of withdrawal discomfort and to dependence. Entering MPPS ratings of urges to smoke in the given week into regression analysis resulted in the general urges to smoke, rather than urges elicited by other people's smoke, becoming a significant predictor of smoking status in the following week. In patients who maintained continuous abstinence throughout 4 weeks of treatment the pleasantness ratings remained stable, while the ratings of temptation steadily decreased.

Conclusions  In abstaining smokers, the like or dislike of other people's smoke is not related to relapse. The temptation to smoke elicited by other people's smoke is related to outcome, but only as an indicator of a general ‘temptation threshold’. Patients who find other people's smoke tempting can be reassured that this reaction will gradually decrease.
Scottish smoke‐free legislation and trends in smoking cessation
Authors: Fowkes Freya J. I. , Stewart Marlene C. W. , Fowkes F. Gerald R. , Amos Amanda , Price Jackie F.
Published: October 2008

Aim  To investigate trends in smoking cessation before and after the introduction of Scottish smoke‐free legislation and to assess the perceived influence of the legislation on giving up smoking and perceptions of the legislation in smokers.

Design, setting and participants  Longitudinal data on smoking cessation were obtained from 1998 to 2007 on a cohort of 3350 Scottish adults aged between 50 and 75 years at baseline. All members of the cohort were participating in a clinical trial of aspirin in people at moderately increased risk of cardiovascular events. A subgroup of 474 participants who had smoked in the year prior to the introduction of legislation in March 2006 also completed a questionnaire on the influence and perceptions of the smoke‐free legislation following its introduction.

Measurements   Smoking status was recorded yearly, including dates of quitting and restarting. Participants who gave up smoking for at least 3 months were recorded as having quit smoking. The questionnaire included scales on whether the smoke‐free legislation had helped/influenced cessation, made the individual think about/prompt them to quit and perceptions of the legislation.

Findings  The odds of smokers quitting annually increased throughout the 7‐year period prior to introduction of the smoke‐free legislation to 2 years afterwards (odds ratio 1.09, 95% confidence interval 1.05–1.12, P < 0.001). During 2006, the pattern of quarterly quitting rates changed, with an increase in quit rates (to 5.1%) in the 3‐month period prior to introduction of the legislation (January–March 2006). Socio‐economic status was not related to smoking cessation. In the subgroup completing the questionnaire (n = 474), 57 quit smoking between June 2005 and May 2007 and 43.9% of these said that the smoke‐free legislation had helped them to quit. Most (>70%) smokers were positive about the legislation, especially those from more affluent compared with more deprived communities (P = 0.01).

Conclusions  The Scottish smoke‐free legislation was associated with an increase in the rate of smoking cessation in the 3‐month period immediately prior to its introduction. Overall quit rates in the year the legislation was introduced and the subsequent year were consistent with a gradual increase in quit rates prior to introduction of the legislation. Socio‐economic status was not related to smoking cessation, but individuals from more affluent communities were more positive about the legislation.
Infusion of haplo‐identical killer immunoglobulin‐like receptor ligand mismatched NK cells for relapsed myeloma in the setting of autologous stem cell transplantation
Authors: Shi Jumei , Tricot Guido , Szmania Susann , Rosen Nancy , Garg Tarun K. , Malaviarachchi Priyangi A. , Moreno Amberly , DuPont Bo , Hsu Katharine C. , Baxter‐Lowe Lee Ann , Cottler‐Fox Michele , Shaughnessy Jr John D. , Barlogie Bart , Van Rhee Frits
Published: October 2008

Killer immunoglobulin‐like receptor (KIR)‐ligand mismatched natural killer (NK) cells play a key role in achieving durable remission after haplo‐identical transplantation for acute myeloid leukaemia. We investigated the feasibility of transfusing haplo‐identical, T‐cell depleted, KIR‐ligand mismatched NK cells, after conditioning therapy with melphalan and fludarabine, to patients with advanced multiple myeloma (MM) followed by delayed rescue with autologous stem cells. No graft‐versus‐host disease or failure of autologous stem cells to engraft was observed. There was significant variation in the number of allo‐reactive NK cells transfused. However, all NK products containing allo‐reactive NK cells killed the NK cell target K562, the MM cell line U266, and recipient MM cells when available. Post NK cell infusion there was a rise in endogenous interleukin‐15 accompanied by increasing donor chimaerism. Donor chimaerism was eventually lost, which correlated with the emergence of potent host anti‐donor responses indicating that the immunosuppressive properties of the conditioning regimen require further optimization. Further, blocking of inhibitory KIR‐ligands with anti‐human leucocyte antigen antibody substantially enhanced killing of MM cells thus highlighting the potential for modulating NK/MM cell interaction. Encouragingly, 50% of patients achieved (near) complete remission. These data set the stage for future studies of KIR‐ligand mismatched NK cell therapy in the autologous setting.
Identification of an immunodominant region of Fel d 1 and characterization of constituent epitopes
Authors: Bateman E. A. L. , Ardern‐Jones M. R. , Ogg G. S.
Published: October 2008

Background
Characterization of T cell epitopes restricted by common HLA alleles is a powerful tool in the understanding of the immune responses to allergens and for the identification of potential peptides for future peptide immunotherapy (PIT). One important requirement is the identification and use of peptides that will bind to HLA molecules covering a large proportion of the population.

Objective
To identify commonly recognized CD4+ T cell epitopes in Fel d 1, restricted through frequently expressed HLA molecules for potential future use in PIT.

Methods
HLA matched antigen presenting cells, HLA blocking antibodies, and peptide truncations were used in ELISpot assays to establish HLA‐restricted T cell epitopes. Cytokine responses were measured by ex vivo and cultured IFN‐γ, IL‐4, and IL‐10 ELISpots.

Results
Responses to an immunodominant region of chain 2 were identified in the majority of atopic individuals and epitopes restricted by HLA‐DQB1*06 and ‐DPB1*0401 were characterized in detail. Significantly higher ex vivo IL‐4 and lower IFN‐γ responses were observed to both epitopes in individuals with atopic dermatitis (AD) compared with those without disease. IL‐10 responses were significantly lower in those with AD in the individuals with HLA‐DPB1*0401.

Conclusions
We have identified an immunodominant region of Fel d 1 which is frequently recognized by CD4+ T cells from atopic individuals and contains epitopes that are restricted by very common HLA alleles.
Alpha‐T‐catenin (CTNNA3) gene was identified as a risk variant for toluene diisocyanate‐induced asthma by genome‐wide association analysis
Authors: Kim S‐H. , Cho B‐Y. , Park C‐S. , Shin E‐S. , Cho E‐Y. , Yang E‐M. , Kim C‐W. , Hong C‐S. , Lee J‐E. , Park H‐S.
Published: October 2008

Background
Toluene diisocyanate (TDI) is the most important cause of occupational asthma, but the genetic mechanism of TDI‐induced asthma is still unknown.

Objective
The objective of the study was to identify susceptibility alleles associated with the TDI‐induced asthma phenotype.

Methods
We conducted a genome‐wide association study in 84 patients with TDI‐induced asthma and 263 unexposed healthy normal controls using Affymetrix 500K SNPchip. We also investigated the relationships between genetic polymorphisms and transcript levels in Epstein–Barr virus‐transformed lymphoblastoid cell lines from patients with TDI‐induced asthma enrolled in this study.

Results
Genetic polymorphisms of CTNNA3 (catenin alpha 3, alpha‐T catenin) were significantly associated with the TDI‐induced asthma phenotype (5.84 × 10−6 for rs10762058, 1.41 × 10−5 for rs7088181, 2.03 × 10−5 for rs4378283). Carriers with the minor haplotype, HT2 [GG], of two genetic polymorphisms (rs10762058 and rs7088181) showed significantly lower PC20 methacholine level (P=0.041) and lower mRNA expression of CTNNA3 than non‐carriers (P=0.040). A genetic polymorphism in the 3′ downstream region of CTNNA3 (rs1786929), as identified by DNA direct sequencing, was significantly associated with the TDI‐induced asthma phenotype (P=0.015 in recessive analysis model) and the prevalence of serum‐specific IgG to cytokeratin 19 (P=0.031).

Conclusion
These findings suggested that multiple genetic polymorphisms of CTNNA3 may be determinants of susceptibility to TDI‐induced asthma.
Impact of thyroid function and polymorphisms in the type 2 deiodinase on blood pressure: the Rotterdam Study and the Rotterdam Scan Study
Authors: Van Der Deure Wendy M. , Peeters Robin P. , Uitterlinden André G. , Hofman Albert , Breteler Monique M. B. , Witteman Jacqueline , Visser Theo J.
Published: October 2008

Introduction  Thyroid function and genetic variation in the hypothalamus–pituitary–thyroid axis have been implicated in blood pressure regulation and susceptibility to hypertension. However studies conducted thus far were small with controversial results.

Objective  To examine whether serum thyroid parameters and polymorphisms in the type 2 deiodinase and the TSH receptor are associated with blood pressure and the presence of hypertension in two large cohorts of elderly subjects.

Design and participants  We studied a random sample of 1444 subjects of the Rotterdam study, and 997 subjects of the Rotterdam Scan study, two population‐based cohort studies among elderly individuals aged 55–90 years.

Outcome measurements  Data on blood pressure and hypertension were obtained, and serum thyroid parameters, D2‐Thr92Ala, D2‐ORFa‐Gly3Asp and TSHR‐Asp727Glu polymorphisms were determined.

Results  In contrast to previous findings, no consistent and/or significant associations were found between serum TSH and FT4 and blood pressure in both cohorts. In addition, the D2‐Thr92Ala, D2‐ORFa‐Gly3Asp and TSHR‐Asp727Glu polymorphisms were not associated with blood pressure or the risk of hypertension.

Conclusions  In two large populations of elderly subjects, neither serum thyroid parameters nor polymorphisms in the type 2 deiodinase and the TSH receptor, were associated with blood pressure or the presence of hypertension. Our data suggest that thyroid function is not an important determinant of hypertension in elderly Dutch subjects.
Continuous exposure to infectious pancreatic necrosis virus during early life stages of rainbow trout, Oncorhynchus mykiss (Walbaum)
Authors: Bebak J , McAllister P E
Published: October 2008

Rainbow trout, Oncorhynchus mykiss (Walbaum), were exposed continuously to infectious pancreatic necrosis virus (IPNV) at 0, 101, 103 or 105 plaque forming units (pfu) L−1 of water to estimate the effects of chronic IPNV exposure on early life stages. Fish density averaged 35 fish L−1 (low density) or 140 fish L−1 (high density), and the tank flow rate was 250 mL−1 min. Virus exposure began at 6 days before hatch and continued until fish were 44 days old. Cumulative per cent mortality, analysis of survival and hazard functions, and discrete‐time event analysis were used to explore the patterns of survival and mortality. In eggs and fish exposed to IPNV, mortality significantly greater than in the 0 pfu L−1 exposure did not occur until IPNV concentration was 105 pfu L−1 at low fish density and 103 pfu IPNV L−1 at high fish density. These results suggest that in the natural aquatic environment, where rainbow trout densities are likely to be considerably lower than in this study, mortality resulting from infection with IPNV will very likely not occur when ambient concentrations of virus are ≤103 pfu IPNV L−1. In aquaculture rearing units, trout density is likely to be as high or higher than the densities used in this study. Therefore, continuous inputs of virus at concentrations greater than 101 pfu L−1 may result in IPN epidemics in aquaculture facilities.
Effects of a combination of napping and bright light pulses on shift workers' sleepiness at the wheel: a pilot study
Authors: LEGER DAMIEN , PHILIP PIERRE , JARRIAULT PHILIPPE , METLAINE ARNAUD , CHOUDAT DOMINIQUE
Published: October 2008

To assess the effects of napping + bright light on shift work drivers sleepiness at the wheel, we performed a pilot study on nine shift workers on three shifts (morning, afternoon, night), driving on a private road circuit. Sleepiness at the wheel was measured by ambulatory polysomnography and assessed using 30‐s segments of recordings with a percentage of theta electroencephalogram of at least 50% (15 s) of the period recorded. Sleepiness was also assessed by the Stanford Sleepiness Scale (SSS). Participants drove the same car on two similar 24‐h periods of work, with three drivers in each shift (morning, afternoon, night), separated by 3 weeks. During the baseline period, the subjects were told to manage their rest as usual. During the second experimental period, they had to rest lying in a dark room with two naps of 20 min and then exposed to bright light (5000 lux) for 10 min. Subjects showed a significantly decreased sleepiness at the wheel with an average of 10.7 ± 6.7 episodes of theta sleep during the baseline (766 ± 425 s) versus 1.0 ± 1.0 episode lasting 166 ± 96 s during the second period (P = 0.016; P = 0.0109). The percentage of driving asleep was also significantly reduced (3.7% ± 1.9% versus 0.9% ± 0.6%, P = 0.0077). The average SSS score in the group decreased from 2.76 ± 1.27 to 2.28 ± 0.74 (P = 0.09). In this pilot and preliminary study, a combination of napping and bright light pulses was powerful in decreasing sleepiness at the wheel of shift work drivers.