bluuebunny/crossref_metadata_2025 huggingface dataset:
Conditional persistence in logistic models via nonlinear diffusion
Authors: Cantrell Robert Stephen , Cosner Chris
Published: July 2007

A nonlinear diffusion process modelling aggregative dispersal is combined with local (in space) population dynamics given by a logistic equation and the resulting growth-dispersal model is analysed. The nonlinear diffusion process models aggregation via a diffusion coefficient, which is decreasing with respect to the population density at low densities. This mechanism is similar to area-restricted search, but it is applied to conspecifics rather than prey. The analysis shows that in some cases the models predict a threshold effect similar to an Allee effect. That is, for some parameter ranges, the models predict a form of conditional persistence where small populations go extinct but large populations persist. This is somewhat surprising because logistic equations without diffusion or with non-aggregative diffusion predict either unconditional persistence or unconditional extinction. Furthermore, in the aggregative models, the minimum patch size needed to sustain an existing population at moderate to high densities may be smaller than the minimum patch size needed for invasibility by a small population. The tradeoff is that if a population is inhabiting a large patch whose size is reduced below the size needed to sustain any population, then the population on the patch can be expected to experience a sudden crash rather than a steady decline.
An application of the theory of monotone systems to an electrical circuit
Authors: Sánchez Luis A.
Published: July 2007

This paper considers the dynamics of a three-dimensional nonlinear autonomous system that models the behaviour of an electrical circuit. Results on the existence of stable periodic oscillations and the behaviour of Poincaré–Bendixon types are obtained. The work is based on a variation of classical monotone systems theory.
Quasiregular mappings and Young measures
Authors: Astala Kari , Faraco Daniel
Published: July 2007

W1,p-gradient Young measures supported in the set Q2(K) of two-dimensional K-quasiconformal matrices are studied. We prove that these Young measures can be generated by gradients of K-quasiregular mappings. This leads, for example, to the 0-1 law for quasiregular W1,p-gradient Young measures and other quasiregular properties such as higher integrability.
Convergence theorems for intermediate problems. II
Authors: Beattie Christopher A. , Greenlee W. M.
Published: July 2007

Convergence theorems for the practical eigenvector free methods of Gay and Goerisch are obtained under a variety of hypotheses, so that our theorems apply to both traditional boundary-value problems and atomic problems. In addition, we prove convergence of the T*T method of Bazley and Fox without an alignment of projections hypothesis required in previous literature.
On a variational principle related to rank-one convexity
Authors: Pedregal Pablo
Published: July 2007

By means of a certain variational principle, where rank-one convexity enters in a fundamental way as part of feasibility, we construct a whole class of rank-one convex functions. We show the existence of optimal paths and motivate our analysis by the issue of the equivalence of quasiconvexity and rank-one convexity for 2 × 2 matrices.
Basic structures of hyperbolic relaxation systems
Authors: Yong Wen-An
Published: July 2007

This work is concerned with basic structural properties of first-order hyperbolic systems with source terms divided by a small parameter ε. We identify a relaxation criterion necessary for the solution sequences indexed with ε to have reasonable limits as ε goes to zero. This relaxation criterion is shown to imply hyperbolicity of the reduced systems governing the limits. Moreover, we introduce a so-called GC-stability theory and strengthen the hyperbolicity result. The latter shows that there are no linearly stable hyperbolic relaxation approximations for non-hyperbolic conservation laws.
On uniform H2-estimates in periodic homogenization
Authors: Conca C. , Vanninathan M.
Published: July 2007

We introduce what are called regular materials for which, by definition, the corresponding solution of the classical periodic homogenization problem remains bounded in . We give examples of two types of such materials depending on whether the coefficients representing them belong to W1,∞ or not. A complete characterization is obtained in the former case.
On lower semicontinuity and relaxation
Authors: Fonseca Irene , Leoni Giovanni
Published: July 2007

Lower semicontinuity and relaxation results in BV are obtained for multiple integrals

where the energy density f satisfies lower semicontinuity conditions with respect to (x, u) and is not subjected to coercivity hypotheses. These results call for methods recently developed in the calculus of variations.
Finite-difference approximation of free-discontinuity problems
Authors: Gobbino Massimo , Mora Maria Giovanna
Published: July 2007

We approximate functionals depending on the gradient of u and on the behaviour of u near the discontinuity points by families of non-local functionals where the gradient is replaced by finite differences. We prove pointwise convergence, Γ-convergence and a compactness result, which implies, in particular, the convergence of minima and minimizers.
Introduction & Overview to Symposium 240: Binary Stars as Critical Tools and Tests in Contemporary Astrophysics
Authors: Guinan Edward F. , Harmanec Petr , Hartkopf William
Published: July 2007

An overview is presented of the many new and exciting developments in binary and multiple star studies that were discussed at IAU Symposium 240. Impacts on binary and multiple star studies from new technologies, techniques, instruments, missions and theory are highlighted. It is crucial to study binary and multiple stars because the vast majority of stars (>60%) in our Galaxy and in other galaxies consist, not of single stars, but of double and multiple star systems. To understand galaxies we need to understand stars, but since most are members of binary and multiple star systems, we need to study and understand binary stars. The major advances in technology, instrumentation, computers, and theory have revolutionized what we know (and also don't know) about binary and multiple star systems. Data now available from interferometry (with milliarcsecond [mas] and sub-mas precisions), high-precision radial velocities (∼1-2 m/s) and high precision photometry (<1–2 milli-mag) as well as the wealth of new data that are pouring in from panoramic optical and infrared surveys (e.g., > 10,000 new binaries found since 1995), have led to a renaissance in binary star and multiple star studies. For example, advances have lead to the discovery of new classes of binary systems with planet and brown dwarf components (over 200 systems). Also, extremely valuable data about binary stars are available across the entire electromagnetic spectrum — from gamma-ray to IR space missions and from the ground using increasingly more powerful and plentiful optical and radio telescopes as well as robotic telescopes. In the immediate future, spectral coverage could even be extended beyond the radio to the first detection of gravity waves from interacting close binaries. Also, both the quality and quantity of data now available on binary and multiple stars are making it possible to gain unprecedented new insights into the structure, and formation and evolution of binary stars, as well as providing valuable astrophysical information (like precise stellar masses, radii, ages, luminosities and distances) to test and constrain current astrophysical theory. These major advances permit tests of current theories and ideas in stellar astrophysics and provide the foundations for the next steps in modeling and improvements in theory to be taken.
Eclipsing Binaries: Tools for Calibrating the Extragalactic Distance Scale
Authors: Bonanos Alceste Z.
Published: July 2007

In the last decade, over 7000 eclipsing binaries have been discovered in the Local Group through various variability surveys. Measuring fundamental parameters of these eclipsing binaries has become feasible with 8 meter class telescopes, making it possible to use eclipsing binaries as distance indicators. Distances with eclipsing binaries provide an independent method for calibrating the extragalactic distance scale and thus determining the Hubble constant. This method has been used for determining distances to eclipsing binaries in the Magellanic Clouds and the Andromeda Galaxy and most recently to a detached eclipsing binary in the Triangulum Galaxy by the DIRECT Project. The increasing number of eclipsing binaries found by microlensing and variability surveys also provide a rich database for advancing our understanding of star formation and evolution.
Toward a Common Language: the Washington Multiplicity Catalog
Authors: Hartkopf William I.
Published: July 2007

Due to improvements in technology (interferometers, precision radial-velocity techniques, etc.), the traditional separation/period regimes of “wide” and “close” binaries are witnessing increasing overlap. This is expected to lead to increasing confusion in component identification, since different observing techniques adopted their own rules for designation of these components. A quick overview will be given of the Washington Multiplicity Catalog, an effort to create a common nomenclature scheme for all types of stellar and sub-stellar companions.
Polaris: Mass and Multiplicity
Authors: Evans Nancy Remage , Schaefer Gail , Bond Howard E. , Nelan Edmund , Bono Giuseppe , Karovska Margarita , Wolk Scott , Sasselov Dimitar , Guinan Edward , Engle Scott , Schlegel Eric , Mason Brian
Published: July 2007

Polaris, the nearest and brightest classical Cepheid, is a member of at least a triple system. It has a wide (18″) physical companion, the F-type dwarf Polaris B. Polaris itself is a single-lined spectroscopic binary with an orbital period of ∼30 years (Kamper 1996). By combining Hipparcos measurements of the instantaneous proper motion with long-term measurements and the Kamper radial-velocity orbit, Wielen et al (2000) have predicted the astrometric orbit of the close companion. Using the Hubble Space Telescope and the Advanced Camera for Surveys' High-Resolution Channel with an ultraviolet (F220W) filter, we have now directly detected the close companion. Based on the Wielen et al orbit, the Hipparcos parallax, and our measurement of the separation (0″.176 ± 0″.002), we find a preliminary mass of 5.0 ± 1.5 M⊙ for the Cepheid and 1.38 ± 0.61 M⊙ for the close companion. These values will be refined by additional HST observations scheduled for the next 3 years.

We have also obtained a Chandra ACIS-I image of the Polaris field. Two distant companions C and D are not X-rays sources and hence are not young enough to be physical companions of the Cepheid. There is one additional stellar X-ray source in the field, located 253″ from Polaris A, which is a possible companion. Further investigation of such a distant companion is valuable to confirm the full extent of the system.
Binary Stars in the Orion Nebula Cluster
Authors: Köhler Rainer , Petr-Gotzens Monika G. , McCaughrean Mark J. , Bouvier Jerome , Duchêne Gaspard , Quirrenbach Andreas , Zinnecker Hans
Published: July 2007

We report on a high-spatial-resolution survey for binary stars in the periphery of the Orion Nebula Cluster, at 5–15 arcmin (0.65 – 2 pc) from the cluster center. We observed 228 stars with adaptive optics systems, in order to find companions at separations of 0.13 – 1.12 arcsec (60 – 500 AU), and detected 13 new binaries. Combined with the results of Petr (1998), we have a sample of 275 objects, about half of which have masses from the literature and high probabilities to be cluster members. We used an improved method to derive the completeness limits of the observations, which takes into account the elongated point spread function of stars at relatively large distances from the adaptive optics guide star. The multiplicity of stars with masses >2 M⊙ is found to be significantly larger than that of low-mass stars. The companion star frequency of low-mass stars is comparable to that of main-sequence M-dwarfs, less than half that of solar-type main-sequence stars, and 3.5 to 5 times lower than in the Taurus-Auriga and Scorpius-Centaurus star-forming regions. We find the binary frequency of low-mass stars in the periphery of the cluster to be the same or only slightly higher than for stars in the cluster core (< 3′ from θ1C Ori). This is in contrast to the prediction of the theory that the low binary frequency in the cluster is caused by the disruption of binaries due to dynamical interactions. There are two ways out of this dilemma: Either the initial binary frequency in the Orion Nebula Cluster was lower than in Taurus-Auriga, or the Orion Nebula Cluster was originally much denser and dynamically more active. A detailed report of this work has been published in Astronomy & Astrophysics (Köhler et al. 2006).
Detectability of Planets in Wide Binaries by Ground-Based Relative Astrometry with AO
Authors: Neuhäuser R. , Seifahrt A. , Röll T. , Bedalov A. , Mugrauer M.
Published: July 2007

Many planet candidates have been detected by radial-velocity variations of the primary star; they are planet candidates, because of the unknown orbit inclination. Detection of the wobble in the two other dimensions, to be measured by astrometry, would yield the inclination and, hence, true mass of the companions. We aim to show that planets can be confirmed or discovered in a close visual stellar binary system by measuring the astrometric wobble of the exoplanet host star as a periodic variation of the separation, even from the ground. We test the feasibility with HD 19994, a visual binary with one radial velocity planet candidate. We use the adaptive optics camera NACO at the VLT with its smallest pixel scale (∼ 13 mas) for high-precision astrometric measurements. The separations measured in 120 single images taken within one night are shown to follow white noise, so that the standard deviation can be divided by the square root of the number of images to obtain the precision. In this paper we present the first results and investigate the achievable precision in relative astrometry with adaptive optics. With careful data reduction it is possible to achieve a relative astrometric precision as low as 50 μ as for a 0″.6 binary with VLT/NACO observations in one hour, the best relative astrometric precision ever achieved with a single telescope from the ground. The relative astrometric precision demonstrated here with AO at an 8-m mirror is sufficient to detect the astrometric signal of the planet HD 19994 Ab as periodic variation of the separation between HD 19994 A and B.
Measurement of the Tidal Dissipation in Multiple Stars
Authors: Tokovinin Andrei
Published: July 2007

Considerable effort has been spent to determine the period of tidal circularization in close binaries as a function of age, in order to constrain the tidal dissipation theory. A new, direct method of measuring the tidal dissipation by precise timings of periastron passages in eccentric binaries undergoing circularization is proposed. Such binaries with components just leaving the Main Sequence can be found as inner systems in multiple stars. Three examples are given.
Testing and Improving the Dynamical Theory of Mass Exchange
Authors: Bisikalo Dmitry , Matsuda Takuya
Published: July 2007

The study of the flow structure is of great importance, and the results can be used both for consideration of the evolutionary status of binary stars and for the interpretation of observational data. In this report we present the review of 3D gas dynamic models used for the description of the mass exchange in close binaries.

Main features of the flow structure in steady-state close binaries are summarized. It is shown that in self-consistent considerations the interaction between the stream from the inner Lagrangian point and the forming accretion disk is shock-free, and, hence, a “hot spot” does not form at the outer edge of the disk. To explain the presence of the observed zones of high luminosity in close binaries a self-consistent “hot line” model was proposed according to which the excess energy is released in a shock wave formed due to interaction between the circumdisk halo and the stream. The “hot line” model was confronted with observations and confirmed by virtue of comparison of synthetic and observational light curves for cataclysmic variables and by the analysis of Doppler tomograms.

The special attention is paid to the physics of accretion disks in binary systems and particularly to waves in disks. The possible observational manifestations of the “hot line” wave and two arms of the tidal shocks are discussed. We also suggest that an additional spiral density wave can exist in inner parts of the cold accretion disk. This spiral wave is due to the retrograde precession of flow lines in the binary system. The results of 3D gas dynamic simulation have shown that a considerable increase in the accretion rate (by an order of magnitude) is associated with the formation of the “precessional” spiral wave. Based on this fact we suggest a new mechanism for the superoutbursts and superhumps in close binaries.
Close Pairs as Probes of the Galaxy's Chemical Evolution
Authors: Vanbeveren Dany , De Donder Erwin
Published: July 2007

Understanding the galaxy in which we live is one of the great intellectual challenges facing modern science. With the advent of high quality observational data, the chemical evolution modeling of our galaxy has been the subject of numerous studies in the last years. However, all these studies have one missing element which is ‘the evolution of close binaries’. Reason: their evolution is very complex and single stars only perhaps can do the job. (Un)Fortunately at present we know that a significant fraction of the observed intermediate mass and massive stars are members of a binary or multiple system and that certain objects can only be formed through binary evolution. Therefore galactic studies that do not account for close binaries may be far from realistic. We implemented a detailed binary population in a galactic chemical evolutionary model. Notice that this is not something simple like replacing chemical yields. Here we discuss three topics: the effect of binaries on the evolution of 14N, the evolution of the type Ia supernova rate and the effects on the G-dwarf distribution, the link between the evolution of the r-process elements and double neutron star mergers (candidates of short gamma-ray burst objects).
Halo Wide Binaries and Moving Clusters as Probes of the Dynamical and Merger History of our Galaxy
Authors: Allen Christine , Poveda Arcadio , Hernández-Alcántara A.
Published: July 2007

Wide or fragile pairs are sensitive probes of the galactic potential, and they have been used to provide information about the galactic tidal field, the density of GMC and the masses of dark matter perturbers present in both the disk and the halo. Halo wide binaries and moving clusters, since they are likely to be the remains of past mergers or of dissolved clusters, can provide information on the dynamical and merger history of our Galaxy. Such remnants should continue to show similar motions over times of the order of their ages. We have looked for phase space groupings among the low-metallicity stars of Schuster et al (2006) and have identified a number of candidate moving clusters. In several of the moving clusters we found a wide CPM binary already identified in our catalogue of wide binaries among high-velocity and metal-poor stars (Allen et al 2000a). Spectroscopic follow-up studies of these stars would confirm the physical reality of the groups, as well as allow us to distinguish whether their progenitors are dissolved clusters or accreted extragalactic systems.
Measurements of positive ions and air‐Earth current density at Maitri, Antarctica
Authors: Siingh Devendraa , Pant Vimlesh , Kamra A. K.
Published: July 2007

Simultaneous measurements of the small, intermediate and large positive ions and air‐Earth current density made at a coastal station, Maitri (70°45′52″S, 11°44′03″E, 130 m above sea level), at Antarctica during January–February 2005, are reported. Although small and large positive ion concentrations do not show any systematic diurnal variations, variations in them are almost similar to each other. On the other hand, variations in intermediate positive ion concentrations are independent of variations in the small/large positive ions and exhibit a diurnal variation which is similar to that in atmospheric temperature on fair weather days with a maximum during the day and minimum during the night hours. No such diurnal variation in intermediate positive ion concentration is observed on cloudy days when variations in them are also similar to those in small/large positive ion concentrations. Magnitude of diurnal variation in intermediate positive ion concentration on fair weather days increases with the lowering of atmospheric temperature in this season. Scavenging of ions by snowfall and trapping of α‐rays from the ground radioactivity by a thin layer of snow on ground is demonstrated from observations. Variations in intermediate positive ion concentration are explained on the basis of the formation of new particles by the photolytic nucleation process.
A mixing ratios‐based formulation for multicomponent reactive transport
Authors: De Simoni M. , Sanchez‐Vila X. , Carrera J. , Saaltink M. W.
Published: July 2007

Chemical reactions are driven by disequilibrium, which is often caused by mixing. Therefore quantification of the mixing rate is essential for evaluating the fate of solutes in natural systems, such as rivers, lakes, and aquifers. We propose a novel mixing ratios‐based formulation to evaluate solute concentrations and reaction rates when equilibrium aqueous reactions and precipitation/dissolution of minerals are driven by mixing of different end‐members. Each end‐member corresponds to a water from a given source with a specific chemical signature. The approach decouples the solute transport and chemical speciation problems, so that mixing ratios can be first obtained from the solution of conservative transport and then be used in general speciation codes to obtain the concentration of reacting species. One key finding is a general expression for reaction rates which demonstrates that the amount of reactants evolving into products depends on the rate at which solutions mix. Our formulation constitutes a general framework according to which one can design and interpret experimental analyses devoted to study mixing‐driven reactive processes and obtain transverse dispersion coefficients. The formulation is also proposed as a useful tool to derive analytical solutions of reactive transport problems and may result computationally advantageous when compared to previous approaches to reactive transport modeling. We apply the developed formulation to provide an analytical solution of the reactive transport process resulting from mixing different CaCO3‐saturated waters in a two‐dimensional setup.
Chemical and optical properties of 2003 Siberian forest fire smoke observed at the summit of Mt. Fuji, Japan
Authors: Kaneyasu Naoki , Igarashi Yasuhito , Sawa Yousuke , Takahashi Hiroshi , Takada Hideshige , Kumata Hidetoshi , Höller Robert
Published: July 2007

Boreal forest fires are one of the major emission sources of trace atmospheric constituents in mid and high latitudes in the Northern Hemisphere. From late May through early June 2003, dense smoke aerosols that originated from large forest fires in Siberia were monitored on the summit of Mt. Fuji (3776 m msl.), Japan, a free‐tropospheric height monitoring site where measurements of atmospheric chemistry were briefly intensified during a research project called Atmospheric Environmental Impact of Aerosols in East Asia (AIE). Inside a smoke layer, concentrations of black carbon (BC) measured by an Aethalometer exceeded 1900 ng m−3 with a concurrent increase of carbon monoxide mixing ratio. The slope of a BC/CO regression line was steeper than those obtained in other studies using measurements from lower‐altitude ground monitoring stations, suggesting minimal wet removal processes. The smoke aerosols contained high levels of n‐alkanes of high molecular weight and indicated high carbon preference indices. The time series of CO and O3 mixing ratios indicated a double‐layered vertical structure in which a high O3 mixing ratio layer lay on top of a smoke layer. The wavelength dependence of the absorption coefficient of the smoke showed a slope much steeper than that measured in urban influenced measurements. The higher absorption in the shorter wavelengths was consistent with an abundance of organic species within the smoke.
Severe Acne as a Side Effect of Propranolol and Nadolol in a Migraineur
Authors: Bajwa Zahid H. , Sami Naveed , Flory Christy
Published: July 2007

Beta‐blockers have proven effective in the treatment of migraine. Dermatologic side effects are extremely rare. We report a patient with migraine who developed an acnelike dermatitis with two different beta‐blockers with complete resolution of the acne upon discontinuation of each drug.
Self-assembly of semifluorinated n-alkanethiols on {111}-oriented Au investigated with scanning tunneling microscopy experiment and theory
Authors: Patole Samson N. , Baddeley Christopher J. , O’Hagan David , Richardson Neville V. , Zerbetto Francesco , Zotti Linda A. , Teobaldi Gilberto , Hofer Werner A.
Published: July 2007

The adsorption of semifluorinated alkanethiols on Au/mica was studied by scanning tunneling microscopy (STM). The adlayer structure produced is based on a p(2×2) structure though lines of molecules displayed extensive kinks and bends. In addition, a considerable variation in the contrast of molecular features is found. Molecular modeling calculations confirm that, for the fluorinated thiols, inequivalently adsorbed molecules within a p(2×2) registry are present, an aspect that endows the local structure of the adlayer with a higher flexibility in comparison to nonfluorinated thiols, where one adsorption site is strongly favored in a (√3×√3)R30° structure. Simulated STM imaging on the optimized systems successfully recovered the effects on the molecular feature contrast induced by the flexibility of the fluorinated thiol adlayer.
Nonideality in diffusion of ionic and hydrophobic solutes and pair dynamics in water-acetone mixtures of varying composition
Authors: Gupta Rini , Chandra Amalendu
Published: July 2007

We have performed a series of molecular dynamics simulations of water-acetone mixtures containing either an ionic solute or a neutral hydrophobic solute to study the extent of nonideality in the dynamics of these solutes with variation of composition of the mixtures. The diffusion coefficients of the charged solutes, both cationic and anionic, are found to change nonmonotonically with the composition of the mixtures showing strong nonideality of their dynamics. Also, the extent of nonideality in the diffusion of these charged solutes is found to be similar to the nonideality that is observed for the diffusion and orientational relaxation of water and acetone molecules in these mixtures which show a somewhat similar changes in the solvation characteristics of charged and dipolar solutes with changes of composition of water-acetone mixtures. The diffusion of the hydrophobic solute, however, shows a monotonic increase with increase of acetone concentration showing its different solvation characteristics as compared to the charged and dipolar solutes. The links between the nonideality in diffusion and solvation structures are further confirmed through calculations of the relevant solute-solvent and solvent-solvent radial distribution functions for both ionic and hydrophobic solutes. We have also calculated various pair dynamical properties such as the relaxation of water-water and acetone-water hydrogen bonds and residence dynamics of water molecules in water and acetone hydration shells. The lifetimes of both water-water and acetone-water hydrogen bonds and also the residence times of water molecules are found to increase steadily with increase in acetone concentration. No maximum or minimum was found in the composition dependence of these pair dynamical quantities. The lifetimes of water-water hydrogen bonds are always found to be longer than that of acetone-water hydrogen bonds in these mixtures. The residence times of water molecules are also found to follow a similar trend.
Model, prediction, and experimental verification of composition and thickness in continuous spread thin film combinatorial libraries grown by pulsed laser deposition
Authors: Bassim N. D. , Schenck P. K. , Otani M. , Oguchi H.
Published: July 2007

Pulsed laser deposition was used to grow continuous spread thin film libraries of continuously varying composition as a function of position on a substrate. The thickness of each component that contributes to a library can be empirically modeled to a bimodal cosine power distribution. We deposited ternary continuous spread thin film libraries from Al2O3, HfO2, and Y2O3 targets, at two different background pressures of O2: 1.3 and 13.3Pa. Prior to library deposition, we deposited single component calibration films at both pressures in order to measure and fit the thickness distribution. Following the deposition and fitting of the single component films, we predict both the compositional coverage and the thickness of the libraries. Then, we map the thickness of the continuous spread libraries using spectroscopic reflectometry and measure the composition of the libraries as a function of position using mapping wavelength-dispersive spectrometry (WDS). We then compare the compositional coverage of the libraries and observe that compositional coverage is enhanced in the case of 13.3Pa library. Our models demonstrate linear correlation coefficients of 0.98 for 1.3Pa and 0.98 for 13.3Pa with the WDS.
Threshold voltage shifts in Si passivated (100)Ge p-channel field effect transistors: Insights from first-principles modeling
Authors: Pourtois G. , Houssa M. , De Jaeger B. , Kaczer B. , Leys F. , Meuris M. , Caymax M. , Groeseneken G. , Heyns M. M.
Published: July 2007

An asymmetric shift of the capacitance-voltage characteristics of n-Ge∕Si∕SiOx∕HfO2∕TaN p-channel field effect transistor is reported, namely, a shift of the threshold voltage toward positive values in inversion, while the flatband voltage remains constant. First-principles calculations on silicon-passivated germanium surfaces reveal the formation of a dipole layer at the germanium/silicon interface, which leads to a decrease of the substrate work function/threshold voltage by 0.4–0.5V. Silicon-induced surface states are also found in the germanium band gap. When the substrate Fermi level is located near these states, electrons are transferred to the silicon layer and compensate the work function shift, explaining the absence of flatband voltage shift.
On the uniqueness of the foliation of spheres of constant mean curvature in asymptotically flat 3-manifolds
Authors: Qing Jie , Tian Gang
Published: July 2007

In this note we study constant mean curvature surfaces in asymptotically flat 3-manifolds. We prove that, outside a given compact subset in an asymptotically flat 3-manifold with positive mass, stable spheres of given constant mean curvature are unique. Therefore we are able to conclude that the foliation of stable spheres of constant mean curvature in an asymptotically flat 3-manifold with positive mass outside a given compact subset is unique.
Biological Control of Grape Crown Gall byRahnella aquatilisHX2
Authors: Chen F. , Guo Y. B. , Wang J. H. , Li J. Y. , Wang H. M.
Published: July 2007

Crown gall induced by Agrobacterium vitis is a worldwide plant disease in grape-growing regions. Rahnella aquatilis HX2, a new isolate from vineyard soil in Beijing, showed a significant inhibition effect on the development of crown galls in grapevines. In field trials, immersion of the basal ends of grape cuttings with HX2 cell suspension inhibited or completely prevented crown gall formation caused by A. vitis K308 in the roots of the plants from the cuttings. The 3-year average disease incidence in grape plants treated with HX2 was 30.8% compared to 93.5% in plants without HX2. The culture supernatant of HX2 exhibited a stronger inhibition effect on disease development than did the cell suspension. HX2 could be found in the grape rhizosphere, grown under field conditions, for up to 90 days after inoculation. There was no significant difference in the mean population sizes of root microflora between plants treated and not treated with HX2. The inhibition effect of HX2 on crown gall in sunflower, caused by different agrobacterial strains, varied between 30.7 and 100%, depending on strains. Our results showed that Rahnella aquatilis HX2 may be used as a biological control agent for crown gall disease of grapes.
First Report of Botrytis Blight Caused by Botrytis cinerea on Sweet Basil in Hungary
Authors: Nagy G.
Published: July 2007

In Hungary, sweet basil (Ocimum basilicum L.) is an important medicinal and aromatic plant cultivated over a large area. During field surveys conducted in August and September of 2001 and 2002, significant blossom and leaf blight were observed in plant stands located near Budapest and in the northern region of Hungary at Herencsény. Incidence of disease occurrence ranged between 49 and 92%. Abundant grayish-brown mold consisting of mycelia and conidiophores was observed on necrotic flowers and upper leaves. The fungus was identified as Botrytis cinerea Pers.:Fr.. Conidia were one-celled, ovoid to elliptical, and measured 11.2 × 7.4 μm (7.5 to 15.0 × 5.0 to 10.0 μm). The fungus was isolated on Leonian malt media. In culture, small and large irregular sclerotia, as well as conidiophores, were produced abundantly. Size of large sclerotia ranged between 45 and 95 mm. Sclerotia were produced only in culture. Pathogenicity of two isolates originating from Herencsény was confirmed by spraying eight sweet basil potted plants with a conidial suspension (6.3 × 105 conidia/ml) made from a pure culture. Two noninoculated plants served as controls. Half of the plants were wounded with needles to make incisions on the leaves and flower axes prior to the inoculation, while the remaining plants were directly sprayed. After inoculation, plants were kept in plastic bags in a greenhouse to maintain 90 to 100% relative humidity at 15 to 40°C. After 5 days, water-soaked chlorotic lesions appeared on the wounded leaves of the inoculated plants. After day 12, brown necrosis developed on the flowers of all inoculated plants. Flower axes often broke. Sporulation of the fungus was abundant. Wounding contributed to earlier appearance of the symptoms and more intensive disease development. To our knowledge, this is the first report of botrytis blight on sweet basil in Hungary. In Europe, the disease has been observed in Italy (1) and Greece (2).

References: (1) A. Garibaldi et al. Plant Dis. 81:124, 1997. (2) C. D. Holevas et al. Benaki Phytopathol. Inst. Kiphissia, Athens 19:1, 2000.
The response of Chironomidae to sediment pollution and other environmental characteristics in urban wetlands
Authors: CAREW MELISSA E. , PETTIGROVE VINCENT , COX RENEE L. , HOFFMANN ARY A.
Published: July 2007

1. We investigated the distribution of chironomid taxa in urban wetlands in the greater Melbourne area, Australia, to test if their distribution was influenced by sediment pollution and other environmental variables.

2. For identification of the Chironomidae, DNA markers generated via polymerase chain reaction–restriction fragment length polymorphism of cytochrome c oxidase sub unit I (COI) were validated against morphology and reference specimens for more than 5000 chironomids representing over 80 species. DNA‐based identification generally concurred with morphological separation, but also indicated the existence of cryptic diversity in some genera.

3. Non‐metric multidimensional scaling (NMS) and canonical correspondence analysis (CCA) showed chironomid assemblages were structured among wetlands and could be linked to several habitat characteristics. However, Chironomidae assemblages were only weakly linked to sediment pollution.

4. Logistic regressions identified potential bioindicators of sediment pollution. Riethia stictoptera, Tanytarsus inextentus, Coelopynia and Chironomus ‘februarius’ were negatively associated and Chironomus duplex was positively associated with sediment pollution. Thresholds for the pollution sensitivities of specific species were mostly similar to those established with previous microcosm tests.

5. Several other environmental factors influenced the distribution of specific chironomid taxa. Salinity, substratum type and submerged and riparian vegetation were particularly important.

6. We conclude that specific chironomid taxa rather than assemblages have potential as bioindicators of sediment pollution provided their ecological preferences are considered and their pollution sensitivities are characterized using multiple methods. The integration of DNA‐based techniques should facilitate accurate and rapid identification of bioindicators species.
Phenotype – genotype correlation in eight Polish patients with inherited Factor XIII deficiency: identification of three novel mutations
Authors: IVASKEVICIUS V. , WINDYGA J. , BARAN B. , SCHROEDER V. , JUNEN J. , BYKOWSKA K. , SEIFRIED E. , KOHLER H. P. , OLDENBURG J.
Published: July 2007

Summary.  Inherited factor XIII (FXIII) deficiency is known as one of the most rare blood coagulation disorder in humans. In the present study, phenotype and genotype of eight FXIII deficient Polish patients from five unrelated families were compared. The patients presented with a severe phenotype demonstrated by a high incidence of intracerebral haemorrhages (seven of eight patients), haemarthrosis (six patients) and bleeding due to trauma (five patients). Introduction of regular substitution with FXIII concentrate prevented spontaneous bleeding in seven patients. In all patients, mutations within the F13A gene have been identified revealing four missense mutations (Arg77Cys, Arg260Cys, Ala378Pro, Gly420Ser), one nonsense mutation (Arg661X), one splice site mutation (IVS5‐1 G>A) and one small deletion (c.499–512del). One homozygous large deletion involving exon 15 was detected by failure of PCR product. The corresponding mutations resulted in severely reduced FXIII activity and FXIII A‐subunit antigen concentration, while FXIII B‐subunit antigen remained normal or mildly decreased. Structural analysis demonstrated that the novel Ala378Pro mutation may cause a disruption of the FXIII catalytic triad leading to a non‐functional protein which presumably undergoes premature degradation. In conclusion, the severe phenotype with high incidence of intracranial bleeding and haemarthrosis was in accordance with laboratory findings on FXIII and with severe molecular defects of the F13A gene.
Clostridium difficile colitis in cystic fibrosis patients with and without lung transplantation
Authors: Theunissen C. , Knoop C. , Nonhoff C. , Byl B. , Claus M. , Liesnard C. , Estenne M.J. , Struelens M.J. , Jacobs F.
Published: July 2007

Background. Despite a large carriage rate of Clostridium difficile among cystic fibrosis (CF) patients, C. difficile‐associated disease (CDAD) is rather rare. In case of lung transplantation, the incidence and clinical aspects of CDAD in this patient population are not well known.

Methods. We reviewed the medical files of all CF patients who presented with symptomatic C. difficile infection from January 1998 to December 2004 and compared the incidence, clinical aspects, severity of disease, and clinical outcome between non‐transplanted and transplanted CF patients.

Results. Between 1998 and 2004, 106 adult CF patients were followed at our clinic. Forty‐nine patients underwent lung transplantation; 15 before 1998 and 34 after 1998. The incidence density of CDAD was higher in transplanted CF patients as compared with non‐transplanted CF patients (24.2 vs. 9.5 episodes/100,000 patient‐days; risk ratio: 2.93 [1.41–6.08]; P=0.0044). Diarrhea was a very frequent feature, but was notably absent in 20% of the cases. Rates of moderate and severe colitis were similar in both groups. However, only transplanted patients developed complicated colitis. CT scan and endoscopy were performed more frequently in the transplant group. Two transplant recipients died because of CDAD.

Conclusion. CF patients who undergo lung transplantation are at a higher risk of developing CDAD and seem to present more often atypical and/or complicated disease. CDAD should be part of the differential diagnosis in case of digestive symptoms, even in the absence of diarrhea, and requires early treatment.
Trying to Get Us to Change Course
Authors: Holt Rush
Published: July 2007

An Inconvenient Truth
.
Davis Guggenheim, Director
. Paramount Classics, Hollywood, CA, 2006. 97 minutes. DVD, $29.99.
www.climatecrisis.net/

An Inconvenient Truth
. The Planetary Emergency of Global Warming and What We Can Do About It.
By Al Gore
. Rodale, New York, 2006. 328 pp. Paper, $21.95, C$28.95. ISBN 9781594865671.

In the film and accompanying book, Gore summarizes the case for taking action to alleviate the threats posed by human-induced changes in the climate.
The Herpes Simplex Virus Type 1 UL3 Transcript Starts within the UL3 Open Reading Frame and Encodes a 224-Amino-Acid Protein
Authors: Markovitz Nancy S.
Published: July 2007

Several different herpes simplex viruses (HSVs) and vectors are being explored as therapeutic products for use in the treatment of cancer and neurological disorders. The viral strain and the combination of mutant viral genes that ultimately may serve as a safe and optimal backbone for such products are still being explored. The large genome size and complexity of the viral life cycle make such determinations difficult, because the significance of differences between proposed products is difficult to evaluate. For example, we previously reported that two lineages of γ34.5-deleted HSVs used in clinical studies differ from each other in the size of the UL3 protein expressed (M. J. Dambach et al., Mol. Ther.
13:
891-898, 2006). Because the function of UL3 is not known and UL3 gene expression is poorly understood, the significance of such a difference cannot be predicted. Here, I begin to address the function of UL3 by investigating UL3 gene expression. I report that the transcript start site of UL3 mRNA isolated from HSV type 1 (HSV-1)-infected cells maps to a position downstream of the predicted translation start site. By constructing and characterizing the recombinant virus CB8116, which has a mutation in the first in-frame start codon of this UL3 transcript, I demonstrated that UL3 protein translation initiates at the second in-frame start codon of the UL3 open reading frame. This information adds to the body of basic knowledge of HSV-1 biology that forms the foundation for our current understanding of HSV-based products. Future research on HSV-1 biology will facilitate the rational design and evaluation of future generations of therapeutic viruses.
Astrocyte Indoleamine 2,3-Dioxygenase Is Induced by the TLR3 Ligand Poly(I:C): Mechanism of Induction and Role in Antiviral Response
Authors: Suh Hyeon-Sook , Zhao Meng-Liang , Rivieccio Mark , Choi Shinyeop , Connolly Erin , Zhao Yongmei , Takikawa Osamu , Brosnan Celia F. , Lee Sunhee C.
Published: July 2007

Indoleamine 2,3-dioxygenase (IDO) is the first and rate-limiting enzyme in the kynurenine pathway of tryptophan catabolism and has been implicated in neurotoxicity and suppression of the antiviral T-cell response in HIV encephalitis (HIVE). Here we show that the Toll-like receptor 3 (TLR3) ligand poly(I:C) (PIC) induces the expression of IDO in human astrocytes. PIC was less potent than gamma interferon (IFN-γ) but more potent than IFN-β in inducing IDO. PIC induction of IDO was mediated in part by IFN-β but not IFN-γ, and both NF-κB and interferon regulatory factor 3 (IRF3) were required. PIC also upregulated TLR3, thereby augmenting the primary (IFN-β) and secondary (IDO and viperin) response genes upon subsequent stimulation with PIC. In HIVE, the transcripts for TLR3, IFN-β, IDO, and viperin were increased and IDO immunoreactivity was detected in reactive astrocytes as well as macrophages and microglia. PIC caused suppression of intracellular replication of human immunodeficiency virus pseudotyped with vesicular stomatitis virus G protein and human cytomegalovirus in a manner dependent on IRF3 and IDO. The involvement of IDO was demonstrated by partial but significant reversal of the PIC-mediated antiviral effect by IDO RNA interference and/or tryptophan supplementation. Importantly, the cytokine interleukin-1 abolished IFN-γ-induced IDO enzyme activity in a nitric oxide-dependent manner without suppressing protein expression. Our results demonstrate that IDO is an innate antiviral protein induced by double-stranded RNA and suggest a therapeutic utility for PIC in human viral infections. They also show that IDO activity can be dissociated from protein expression, indicating that the local central nervous system cytokine and nitric oxide environment determines IDO function.
A randomised controlled trial evaluating an alternative mouse and forearm support on upper body discomfort and musculoskeletal disorders among engineers
Authors: Conlon C F , Krause N , Rempel D M
Published: July 2007

Objectives:

The aim of this intervention study was to determine the effects of an alternative mouse and/or a forearm support board on the change in upper body discomfort scores and the development of incident musculoskeletal disorders.

Methods:

This randomised controlled intervention trial followed 206 engineers for one year. Participants were randomised to receive (1) a conventional mouse only, (2) an alternative mouse only, (3) a forearm support board, or (4) an alternative mouse plus forearm support board. Outcome measures included weekly upper body discomfort scores and incident musculoskeletal disorders.

Results:

During the study, 42 participants were diagnosed with an incident musculoskeletal disorder. The group that received the forearm support board experienced a reduction in their right upper extremity discomfort (beta-coefficient −0.35, 95% CI −0.67 to −0.03) in comparison to those who did not receive a forearm board. The group that received the alternative mouse had a protective, but non-significant (p = 0.20), effect on incident cases of right upper extremity musculoskeletal disorders (HR 0.57, 95% CI 0.24 to 1.34) and a non-significant reduction in neck/shoulder discomfort (beta-coefficient −0.23, 95% CI −0.056 to 0.10) in comparison to those who received a conventional mouse.

Conclusions:

In engineers who use a computer for more than 20 h per week, a forearm support board may reduce right upper extremity discomfort attributed to computer use.