bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and morphology of nanocomposite films prepared from polyvinyl alcohol and silver nitrate: Influence of thermal treatment
Authors: Clémenson S. , David L. , Espuche E.
Published: May 2007

Hybrid organic/inorganic films have been prepared from an aqueous solution of polyvinyl alcohol (PVA) and silver nitrate (AgNO3). The silver nanoparticles have been generated in the PVA matrix by thermal treatments. The structure and the morphology of the hybrid films have been studied as a function of the silver precursor concentration and of the annealing conditions for a wide range of annealing temperatures. It was shown that in the uncured hybrid film most of the silver ions were initially coordinated with the polymer OH groups to form a chelate structure. A nanostructuration effect leading to the formation of crystalline silver nanoparticles was evidenced for annealing treatments performed at temperatures higher than 90 °C. For a curing temperature equal to 110 °C, the sizes of the formed nanoparticles were only slightly increasing as a function of annealing time and the effect of AgNO3 complex amount in this curing condition was also significant, but slight. Annealing at a temperature equal to 160 °C thus at a temperature for which a part of the crystalline phase of PVA was melt led to an important increase of the size of the generated metal nanoparticles. The evolution of the morphology was discussed for each curing temperature as a function of the kinetics of the nanostructuration, of the size of the matrix amorphous lamellae and of the polymer chain mobility. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2657–2672, 2007
Surface operators in gauge theory
Authors: Witten E.
Published: May 2007

I discuss certain surface operators in gauge theory and their relevance to the ramified case of the geometric Langlands program.
Electric properties of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide—Post‐HF and DFT study
Authors: Benková Zuzana , Černušák Ivan , Zahradník Pavol
Published: May 2007

Dipole moments μ, static electric polarizabilities α, and hyperpolarizabilities β of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide have been evaluated in the DFT and post‐HF approximations. Within the DFT, the family of HCTH and hybrid functionals (B3LYP, B97–1) have been adopted. The qualitative and quantitative performance of both functional types have been examined by confrontation with the CCSD(T) method. The DFT model appears to be adequate for dipole moments and polarizabilities, while the hyperpolarizabilities are exaggerated, especially βyyy (too negative) and βzzz (too positive) components. The replacement of oxygen by sulfur reduces the DFT hyperpolarizability, which contradicts an increase predicted with the post‐HF approach. HCTH dipole moments in majority of cases are in better agreement with the CCSD(T) estimates than are the hybrid functionals. On the other hand, the hybrid functionals perform slightly better for polarizability and hyperpolarizability evaluations. The effects of basis set size with aug‐cc‐pVXZ (X = D, T, Q) on the electric properties have also been studied. The sensitivity of the electric properties to the basis set effects increases from the dipole moment to the hyperpolarizability. The axial αzz and βzzz components display smaller sensitivity to the basis set extension. The carbonyl/thiocarbonyl containing molecules are characterized by negative/positive sign of hyperpolarizability vector projection into the dipole moment direction. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Strömung an einer Luftblase im senkrechten Rohr
Authors: Dumitrescu D. T.
Published: May 2007

Die Aufgabe: Form und Geschwindigkeit einer in einem vertikalen Rohr aufsteigenden, unendlich langen Luftblase zu finden, führt unter Vernachlässigung der Kapillar‐ und Zähigkeitskräfte auf ein Eigenwertproblem der Differentialgleichung Δφ=0, das in erster Annäherung unter der der Wirklichkeit gut entsprechenden Annahme gelöst wird, daß der Meridianschnitt der Blase in der Umgebung der Kuppe durch den Krümmungskreis ersetzt werden kann. Der Eigenwert, der sich als Funktion dieses Krümmungsradius angeben läßt, wird dadurch bestimmt, daß die asymptotische Lösung mit stetiger Tangente in den Krümmungskreis übergehen soll. Berechneter und experimentell gefundener Wert stimmen gut überein.
Risk Assessment and Genetic Counseling for Hereditary Breast and Ovarian Cancer: Recommendations of the National Society of Genetic Counselors
Authors: Berliner Janice L. , Fay Angela Musial
Published: May 2007

These cancer genetic counseling recommendations describe the medical, psychosocial and ethical implications of identifying at‐risk individuals for hereditary breast and ovarian cancer (HBOC) through cancer risk assessment, with or without genetic susceptibility testing. They were developed by members of the Practice Issues Subcommittee of the National Society of Genetic Counselors’ Familial Cancer Risk Counseling Special Interest Group. The information contained in this document is derived from extensive review of the current literature on cancer genetic risk assessment as well as the professional expertise of genetic counselors with significant experience in education and counseling regarding hereditary breast and ovarian cancer. Critical components of the process include the ascertainment of medical and family histories, determination and communication of cancer risk, assessment of risk perception, education regarding the genetics of HBOC, discussion of molecular testing for HBOC if appropriate (including benefits, risks and limitations) and any necessary follow‐up. These recommendations do not dictate an exclusive course of management or guarantee a specific outcome. Moreover, they do not replace the professional judgment of a health care provider based on the clinical situation of a client.
Amla (Emblica officinalisGaertn.) prevents dyslipidaemia and oxidative stress in the ageing process
Authors: Yokozawa Takako , Young Kim Hyun , Ju Kim Hyun , Okubo Tsutomu , Chu Djoing-Chi , Raj Juneja Lekh
Published: May 2007

Amla (Emblica officinalisGaertn.) is widely used in Indian medicine for the treatment of various diseases. We have investigated the effects of amla on the lipid metabolism and protein expression involved in oxidative stress during the ageing process. SunAmla or ethyl acetate extract of amla, a polyphenol-rich fraction, was administered at a dose of 40 or 10 mg/kg body weight per d for 100 d to young rats aged 2 months and aged rats aged 10 months. The lipid levels, such as cholesterol and TAG, in serum and liver were markedly elevated in aged control rats, while they were significantly decreased by the administration of amla. The PPARα is known to regulate the transcription of genes involved in lipid and cholesterol metabolism. The PPARα protein level in liver was reduced in aged control rats. However, the oral administration of amla significantly increased the hepatic PPARα protein level. In addition, oral administration of amla significantly inhibited the serum and hepatic mitochondrial thiobarbituric acid-reactive substance levels in aged rats. Moreover, the elevated expression level of bax was significantly decreased after the oral administration of amla, while the level of bcl-2 led to a significant increase. Furthermore, the expressions of hepatic NF-κB, inducible NO synthase (iNOS), and cyclo-oxygenase-2 (COX-2) protein levels were also increased with ageing. However, amla extract reduced the iNOS and COX-2 expression levels by inhibiting NF-κB activation in aged rats. These results indicate that amla may prevent age-related hyperlipidaemia through attenuating oxidative stress in the ageing process.
Distribution, abundance and reproduction of the Indo-Pacific acorn barnacle Balanus amphitrite (Crustacea: Cirripedia)
Authors: Litulo Carlos
Published: May 2007

The patterns of distribution, abundance and reproduction of the Indo-Pacific barnacle Balanus amphitrite
were surveyed at Costa do Sol mangrove, Maputo Bay, southern Mozambique using stratified sampling
design. Balanus amphitrite exhibited a spatial variation in which high numbers of individuals colonized the
upper stratum in comparison to the lower stratum. Seasonal abundance of B. amphitrite was greater in the
upper stratum and declined in June and September. In contrast, very high densities of individuals were
recorded in winter in the lower stratum. Gonad cycle showed continuous trend and release of embryos
mainly took place in winter (May–July). There was a strong quadratic effect of temperature on breeding
activity of B. amphitrite, with females continuing to brood at lower temperatures. Egg numbers increased
linearly with female size. The success of the reproductive activity may be synchronized within the species,
enhancing the establishment and colonization of B. amphitrite in the study area.
Reproductive seasonal periodicity of the endemic Bermuda killifish Fundulus bermudae in an anchialine pond
Authors: Outerbridge Mark , Davenport John , Glasspool Anne F.
Published: May 2007

A total of 245 individuals from a population of the endemic Bermuda killifish Fundulus bermudae in an
isolated anchialine pond (Mangrove Lake) were trapped between November 2004 and November 2005.
Laboratory analysis of gonad development allowed determination of the seasonal reproductive cycles of
both females and males. A distinctive annual pattern was evident, with female and male gonadal cycles
synchronous throughout the study period. The results indicate that the F. bermudae males and females began
their spawning season in February, but reached primary peaks in May and June respectively. Gonadal
indices abruptly fell after June and continued to fall at a steady rate until September, marking the end of
the spawning season. Gonad recrudescence, as indicated by basal gonad indices, occurred in September
and lasted throughout the autumn and early winter months.
Towards a phylogeny of Euthelepus (Polychaeta: Terebellidae): the absence of synapomorphies in the subfamily Thelepodinae and genera
Authors: Garraffoni André Rinaldo Senna
Published: May 2007

The phylogenetic relationships of Euthelepus (Polychaeta: Terebellidae: Thelepodinae) were studied by
means of a parsimony analysis of 40 external characters. The ingroup terminals included four species of
Euthelepus, and the outgroup included 14 species of eight Thelepodinae genera, three belonging to the
subfamily Terebellinae, one species of Trichobranchinae, and one species of Polycirrinae. Only two most
parsimonious cladograms were found. However, the analysis revealed a large number of homoplastic characters
supporting the thelepodin branches. The monophyly of the genus Euthelepus was not supported, and
the monophyly of the other thelepodin genera, as well as the entire subfamily, is questioned. The large
number of homoplasies indicated by the analysis emphasizes the need to further evaluate these hypotheses
by using additional characters. A re-classification based on phylogenetic results must be considered.
Seasonal variations of epilithic diatoms on different hard substrates, in the northern Adriatic Sea
Authors: Totti Cecilia , Cucchiari Emellina , De Stefano Mario , Pennesi Chiara , Romagnoli Tiziana , Bavestrello Giorgio
Published: May 2007

The colonization of epilithic diatoms on artificial hard substrates (marble, quartzite and slate) was
investigated on a seasonal basis in a subtidal site of the northern Adriatic Sea to determine if
substrate-dependent differences in colonization occurs and to define the seasonal variations of microepilithic
communities in terms of abundance, biomass and community structure. Artificial substrates
(smoothed small discs mounted on a Plexiglas sheet) were placed at a depth of 8 m in April 2003, July
2003, January 2004 and February 2004. The discs were collected after 6–7 weeks for counting and taxonomic
identification of the diatoms. The community structure of epilithic diatoms showed a dominance of
motile species over the entire study period, followed by erect, adnate and tube-dwelling diatoms. Diatom
density showed a marked seasonal variability, ranging from 365±407 (winter 2004) to 557156±82602
cells cm-2 (spring 2004). Biomass ranged from 0.02±0.01 to 17.53±3.20 μg C cm-2. Abundance and
biomass values did not present any significant differences for the three substrates examined.
Zur Vorgehensweise österreichischer Sachverständiger in Obsorge- und Besuchsrechtsverfahren - eine Bestandaufnahme gegenwärtiger Tätigkeit
Authors: Völkl-Kernstock Sabine , Bein Nicolas , Klicpera Christian , Eichberger Heidrun , Friedrich Max H.
Published: May 2007

Zusammenfassung: Fragestellung: Im Rahmen einer Österreich umfassenden Evaluierungsstudie wurden sämtliche gerichtlich zertifizierte Sachverständige (SV), die in Familienrechtsverfahren bestellt werden, per Fragebogen kontaktiert und eine Bestandaufnahme vorherrschender Begutachtungsmodalität und -praxis durchgeführt. Methodik: Ein auf den Regeln der Testtheorie basierender Fragebogen wurde dazu entwickelt. Ergebnisse: Bei einer Rücklaufquote von 33% (n = 25) ist eine grundsätzlich homogene Gewichtung der einzelnen Sorgerechtskriterien durch die SV erkennbar, bei jedoch unterschiedlich angewendeten Methoden und Testverfahren sowie fehlenden einheitlichen Theoriekonzepten. In Ergänzung zu der bisher verfahrensrechtlich möglichen Statusdiagnostik wird von den SV die lösungs- und prozessorientierte Begutachtungsmodalität mehrheitlich als anstrebenswert erachtet. Schlussfolgerungen: Aufgrund der Vakanz standardisierter Verfahren, die im Rahmen von Begutachtungen anwendbar sind, sollten psychologische Testverfahren zur Überprüfung einzelner Entscheidungskriterien nach den Regeln der Testtheorie entwickelt werden. Die Umsetzbarkeit des Ansatzes einer lösungs- bzw. prozessorientierten Sachverständigenarbeit unter Verfassung methodisch-theoretischer sowie normativer Rahmenbedingungen ist auf Ebene der SV und Juristen zu diskutieren.
Fragwürdigkeit eines Gerichtsurteils zur Antidepressiva-Verordnung bei Jugendlichen
Authors: Schepker Renate , Lippert Hans-Dieter , Kölch Michael , Fegert Jörg M.
Published: May 2007

Zusammenfassung: Ein Sozialgericht (SG Dresden, S 16 KR 51/06) hat eine beklagte Krankenkasse dazu verurteilt, einer depressiven Jugendlichen stationär verordnetes Fluoxetin für die Zeit der Ausschleichphase weiter zu erstatten, aber die Klage auf generelle Kostenübernahme bei der Patientin für dieses Medikament ansonsten abgewiesen. Dabei wurden dem Gericht vorliegende Unterlagen, insbesondere die Stellungnahme der DGKJP, fehlerhaft rezipiert und das Gericht hat auf die Schaffung einer eigenen Sachkunde, beispielsweise durch ein Sachverständigengutachten, verzichtet. Eine Bezugnahme auf ein Urteil des Bundessozialgerichts zum off-label-Gebrauch zeigt ebenfalls Recherchemängel des erkennenden Gerichts auf und weist allgemein auf eine unklare Umsetzung dieses Urteils hin. Für den behandelnden Arzt resultiert aus dem SG-Urteil ein therapeutisches, ethisches und haftungsrechtliches Dilemma: ein Absetzen der Substanz gefährdet eventuell die Patientin, ist aber im Urteil so vorgesehen. Durch die mittlerweile erfolgte EMEA-Zulassung der Substanz für Minderjährige über 8 Jahren in Europa ist der Fall vielleicht geklärt - nicht jedoch die Implikationen von juristischen Eingriffen in die ärztliche Therapiefreiheit und wissenschaftlich gut begründbare Therapierationalen.
An unexpected seasonal variability of salinity in the Beaufort Sea upper layer in 1996–1998
Authors: Yang Jiayan , Comiso Josefino C.
Published: May 2007

The salinity in the upper Beaufort Sea from the mixed layer to the thermocline layer was observed by drifting buoys from 1996 to 1998. The salinity in this depth range was lower in winter and higher in the summer, the exact opposite from what one would expect from the seasonal cycle of the freshwater flux associated with the ice melting/freezing and river runoff. In this study, we calculated the daily Ekman transport and upwelling velocity in the Beaufort Sea, using both satellite and buoy data. In fall and winter months, the offshore transport of low‐salinity water from the coastal area toward the interior where the buoys were located was observed to be strong. This horizontal Ekman transport led to the freshening of the surface Ekman layer in the buoy location. The convergence of the Ekman transport resulted in a strong downwelling in the offshore regions, and so the halocline and thermocline were pushed downward. The downwelling then results in the freshening of the subsurface salinity as observed by buoys. Other processes, such as lateral advection, may have also played a role in the subsurface freshening. The lack of in situ observations needed to estimate the salinity gradient makes it difficult to assess more accurately the contribution from lateral advection. A scaling analysis using the salinity climatology suggests that the lateral salinity advection, though considerably smaller than the vertical one, may not be negligible.
Spreading of the Labrador Sea Water to the Irminger and Iceland basins
Authors: Yashayaev Igor , Bersch Manfred , van Aken Hendrik M.
Published: May 2007

Labrador Sea Water (LSW) is a principal convectively‐formed water mass of the subpolar North Atlantic (SPNA). Using extensive oceanographic archives we demonstrate striking changes in SPNA caused by massive LSW production during 1987–1994 and document recent salinification and warming, imminently bringing SPNA to the state last time seen in the 1960s. Two prominent LSW classes are spreading across SPNA since the 1980s. The first, record dense, deep, and voluminous, class has been progressively built by intense winter convection through 1987–1994. Even though most of this LSW has left SPNA, its remnants are still present there. The second, shallower, class strengthens in 2000; over subsequent years its core becomes slightly thicker and deepens. The anomalous signals acquired by these LSW classes in their formation region arrive in the Irminger and Iceland basins with the characteristic delays of two and five years for deeper LSW and a year and four years for shallower LSW.
Water isotope expressions of intrinsic and forced variability in a coupled ocean‐atmosphere model
Authors: Schmidt Gavin A. , LeGrande Allegra N. , Hoffmann Georg
Published: May 2007

Water isotopes provide a clear record of past climate variability but establishing their precise relationship to local or regional climate changes is the key to quantitative interpretations. We have incorporated water isotope tracers within the complete hydrological cycle of Goddard Institute for Space Studies coupled ocean‐atmosphere model (ModelE) in order to assess these relationships. Using multicentennial simulations of the modern (preindustrial) and mid‐Holocene (6 kyr BP) climate, we examine the internal variability and the forced response to orbital and greenhouse gas forcing. Modelled isotopic anomalies clearly reflect climatic changes and, particularly in the tropics, are more regionally coherent than the precipitation anomalies. Matches to observations at the mid‐Holocene and over the instrumental period are good. We calculate water isotope‐climate relationships for many patterns of intrinsic and for forced variability relevant to the Holocene, and we show that in general, calibrations depend on the nature of the climate change. Specifically, we examine relationships between isotopes in precipitation and local temperatures and precipitation amounts in the principal ice coring regions (Greenland, Antarctica, and the tropical Andes) and the seawater isotope‐salinity gradients in the ocean. We suggest that isotope‐based climate reconstructions based on spatial patterns and nonlocal calibrations will be more robust than interpretations based on local relationships.
Mapping rays and secondary craters from the Martian crater Zunil
Authors: Preblich Brandon S. , McEwen Alfred S. , Studer Daniel M.
Published: May 2007

Zunil, a 10.1 km rayed crater in Elysium Planitia, Mars, produced more than 7 × 107 secondary craters ≥15 m in diameter. We mapped Zunil's rays from thermal IR THEMIS nighttime images up to 1700 km from the primary crater and mapped bright and dark ejecta craters (candidate secondaries) up to 3600 km range. Ray segments were mapped up to 450 km east of Zunil and up to 1700 km to the west. Both rays and bright ejecta craters are best detected over terrains with moderate thermal inertia, which are abundant west of but not east of Zunil. Nevertheless, our interpretation is that Zunil was created by a moderately oblique impact from the east. Zunil secondaries are abundant over all terrain types except the Medusae Fossae Formation (MFF). Given the likely age of Zunil (<100 Ma), parts of the MFF must be eroding at ≥0.08 m/Ma. The size‐frequency distribution of the secondaries in Zunil's rays and probable distant secondaries (750–1700 km to the west of Zunil) have a cumulative power law exponent near –5, whereas secondaries between the major rays have an exponent near −3.4. We modeled the size‐velocity relationship for Zunil's ejected fragments; it is consistent with the predictions of Melosh (1984) for spallation of a strong surface layer and demonstrates that the inverse size‐velocity correlation continues up to at least 2 km/s.
Numerical modeling of self‐channeling granular flows and of their levee‐channel deposits
Authors: Mangeney A. , Bouchut F. , Thomas N. , Vilotte J. P. , Bristeau M. O.
Published: May 2007

When not laterally confined in valleys, pyroclastic flows create their own channel along the slope by selecting a given flowing width. Furthermore, the lobe‐shaped deposits display a very specific morphology with high parallel lateral levees. A numerical model based on Saint Venant equations and the empirical variable friction coefficient proposed by Pouliquen and Forterre (2002) is used to simulate unconfined granular flow over an inclined plane with a constant supply. Numerical simulations successfully reproduce the self‐channeling of the granular lobe and the levee‐channel morphology in the deposits without having to take into account mixture concepts or polydispersity. Numerical simulations suggest that the quasi‐static shoulders bordering the flow are created behind the front of the granular material by the rotation of the velocity field due to the balance between gravity, the two‐dimensional pressure gradient, and friction. For a simplified hydrostatic model, competition between the decreasing friction coefficient and increasing surface gradient as the thickness decreases seems to play a key role in the dynamics of unconfined flows. The description of the other disregarded components of the stress tensor would be expected to change the balance of forces. The front's shape appears to be constant during propagation. The width of the flowing channel and the velocity of the material within it are almost steady and uniform. Numerical results suggest that measurement of the width and thickness of the central channel morphology in deposits in the field provides an estimate of the velocity and thickness during emplacement.
Current sheet formation and nonideal behavior at three-dimensional magnetic null points
Authors: Pontin D. I. , Bhattacharjee A. , Galsgaard K.
Published: May 2007

The nature of the evolution of the magnetic field, and of current sheet formation, at three-dimensional (3D) magnetic null points is investigated. A kinematic example is presented that demonstrates that for certain evolutions of a 3D null (specifically those for which the ratios of the null point eigenvalues are time-dependent), there is no possible choice of boundary conditions that renders the evolution of the field at the null ideal. Resistive magnetohydrodynamics simulations are described that demonstrate that such evolutions are generic. A 3D null is subjected to boundary driving by shearing motions, and it is shown that a current sheet localized at the null is formed. The qualitative and quantitative properties of the current sheet are discussed. Accompanying the sheet development is the growth of a localized parallel electric field, one of the signatures of magnetic reconnection. Finally, the relevance of the results to a recent theory of turbulent reconnection is discussed.
An intrinsic stabilization scheme for proper orthogonal decomposition based low-dimensional models
Authors: Kalb Virginia L. , Deane Anil E.
Published: May 2007

Despite the temporal and spatial complexity of common fluid flows, model dimensionality can often be greatly reduced while both capturing and illuminating the nonlinear dynamics of the flow. This work follows the methodology of direct numerical simulation (DNS) followed by proper orthogonal decomposition (POD) of temporally sampled DNS data to derive temporal and spatial eigenfunctions. The DNS calculations use Chorin’s projection scheme; two-dimensional validation and results are presented for driven cavity and square cylinder wake flows. The flow velocity is expressed as a linear combination of the spatial eigenfunctions with time-dependent coefficients. Galerkin projection of these modes onto the Navier-Stokes equations obtains a dynamical system with quadratic nonlinearity and explicit Reynolds number (Re) dependence. Truncation to retain only the most energetic modes produces a low-dimensional model for the flow at the decomposition Re. We demonstrate that although these low-dimensional models reproduce the flow dynamics, they do so with small errors in amplitude and phase, particularly in their long term dynamics. This is a generic problem with the POD dynamical system procedure and we discuss the schemes that have so far been proposed to alleviate it. We present a new stabilization algorithm, which we term intrinsic stabilization, that projects the error onto the POD temporal eigenfunctions, then modifies the dynamical system coefficients to significantly reduce these errors. It requires no additional information other than the POD. The premise that this method can correct the amplitude and phase errors by fine-tuning the dynamical system coefficients is verified. Its effectiveness is demonstrated with low-dimensional dynamical systems for driven cavity flow in the periodic regime, quasiperiodic flow at Re=10000, and the wake flow. While derived in a POD context, the algorithm has broader applicability, as demonstrated with the Lorenz system.
Electrostatic coherent structures: The role of the ions dynamics
Authors: Califano F. , Galeotti L. , Briand C.
Published: May 2007

The Vlasov–Poisson model is the basic framework for the investigation of electrostatic coherent structures (e.g., phase space holes). Directly observed by high resolution space instruments, they are considered as one of the key ingredients of collisionless space and laboratory plasmas. These structures are in general studied numerically in the 1D limit of nonmoving ions eventually leading to a one single final structure (vortex merging). Here we show that, despite the electronic nature of such vortex, the merging process is inhibited by the ions so that many structures are still observed after several ion periods. Furthermore, the ion mass cannot be considered just as a rescaling parameter in the system evolution. Finally, numerical discretization effects significantly influence the nonlinear plasma dynamics even if statistically the number and typical dimension of the structures is unchanged, thus making the results relevant to space observations.
Ion acoustic solitary wave with weakly transverse perturbations in quantum electron-positron-ion plasma
Authors: Mushtaq A. , Khan S. A.
Published: May 2007

The characteristics and stability of ion acoustic solitary wave with transverse perturbations are examined in ultracold quantum magnetospheric plasma consisting of electrons, positrons, and ions. Using the quantum hydrodynamic model, a dispersion relation in the linear regime, and the Kadomtsev-Petviashvili equation in the nonlinear regime are derived. The quantum corrections are studied through quantum statistics and diffraction effects. It is found that compressive solitary wave can propagate in this system. The quantum effects are also studied graphically for both linear and nonlinear profiles of ion acoustic wave. Using energy consideration method, conditions for existence of stable solitary waves are obtained. It is found that stable solitary waves depend on quantum corrections, positron concentration, and direction cosine of the wave vector k along the x axis.
Potential around a charged dust particle in a collisional sheath
Authors: Kompaneets R. , Konopka U. , Ivlev A. V. , Tsytovich V. , Morfill G.
Published: May 2007

By employing a self-consistent kinetic approach, an analytical expression is derived for the potential of a test charge in a weakly ionized plasma with ion drift. The drift is assumed to be due to an external electric field, with the velocity being mobility-limited and much larger than the thermal velocity of neutrals. The derived expression is proven to be in excellent agreement with the measurements by Konopka et al. [Phys. Rev. Lett. 84, 891 (2000)] performed in the sheath region of a rf discharge.
Three-body symmetry-adapted perturbation theory based on Kohn-Sham description of the monomers
Authors: Podeszwa Rafał , Szalewicz Krzysztof
Published: May 2007

An implementation of three-body symmetry-adapted perturbation theory (SAPT) of intermolecular interactions based on Kohn-Sham (KS) description of monomers with dispersion and induction nonadditive energies obtained from KS frequency-dependent density susceptibilities [SAPT(DFT)] is presented. Using the density-fitting approach, the nonadditive dispersion energy can be obtained with O(N5) scaling with respect to the system size, the best scaling among all available methods of evaluating this quantity. Numerical results are reported for the helium, argon, water, and benzene trimers. The nonadditive energy computed for these systems is in a good agreement with benchmarks. Some hybrid perturbational-supermolecular approaches are proposed that can provide—with only O(N5) scaling—nonadditive energies with accuracy comparable to more expensive supermolecular methods, such as the third-order Møller-Plesset perturbation theory. Such approaches can be used for studying nonadditive effects in systems larger than it is currently possible with supermolecular methods at a level high enough to capture all essential components of the three-body interaction energy.
Nonlocal optical effects on the fluorescence and decay rates for admolecules at a metallic nanoparticle
Authors: Vielma Jason , Leung P. T.
Published: May 2007

A phenomenological model is implemented to study the decay rates of fluorescing molecules in the vicinity of a metallic nanoparticle, wherein the nonlocal optical response of the particle is accounted for via the hydrodynamic model for the description of the free electrons in the metal. These nonlocal effects are examined for each of the radiative rate and the nonradiative rate of the admolecule, respectively. In addition, the overall fluorescence rate which includes the enhancement ratio for the driving field intensity is also studied. It is found that for particles of very small sizes (<10nm), the nonlocal effects, in general, lead to significantly greater fluorescence rates and smaller nonradiative decay rates for the admolecules, with the effects on radiative rates depending crucially on the orientation of the molecules. Furthermore, the effects are mostly noticeable for molecules close to the metal particle and in processes where higher multipolar interactions are significant such as those in nonradiative decay processes. Above all, these nonlocal effects can still be observable in the presence of large surface damping imposed on the metallic electrons due to the ultrasmall sizes of these nanoparticles. The relevance of these effects to some of the latest experiments is discussed.
Gas-solid coexistence of adhesive spheres
Authors: Charbonneau P. , Frenkel D.
Published: May 2007

In this note, the authors investigate whether the gas-liquid critical point can remain stable with respect to solidification for narrow attractive interactions down to the Baxter limit. Using a crude cell theory, the authors estimate the necessary conditions for this to be true. Possible realizations are briefly discussed.
Ferroelectric domain structure and c-axis polarization switching in monoclinic Bi4Ti3O12 single crystals
Authors: Kitanaka Yuuki , Noguchi Yuji , Miyayama Masaru
Published: May 2007

Using a piezoresponse force microscope, the authors have investigated the domain structure and the c-axis domain switching taking the spontaneous polarization (Ps) components of the a axis (Ps(a)) and the c axis (Ps(c)) into account in monoclinic Bi4Ti3O12 single crystals. 90° domain walls composed of the Ps(a) component are shown to impede the switching of the Ps(c) domains, leading to a lower remanent polarization along the c axis. The oxidation treatment of the crystals led to a marked increase in the coercive field for the Ps(c) switching, which cannot be explained by the domain wall pinning attributed to oxygen vacancies.
Extremely small hole capture cross sections in HfO2∕HfxSiyOz∕p-Si structures
Authors: Yousif M. Y. A. , Johansson M. , Engström O.
Published: May 2007

Defects in Al∕HfO2∕HfxSiyOz∕p-Si capacitors have been characterized using thermally stimulated current at temperatures between 30 and 300K. The hole activation energy and capture cross section were extracted from the results. The authors observed shallow traps that move with changing the discharging voltage, giving rise to activation energies in the range 0.03–0.14eV. Postmetallization anneal passivated these traps and a deeper trap appears with a significantly lower shift with the discharging voltage. Very small apparent capture cross sections (capture cross section times tunneling probability) have been extracted (10−26–10−18cm2). Simulations agree very well with experimental data.
Derivation of length of carbon nanotube responsible for electron emission from field emission characteristics
Authors: Gotoh Y. , Kawamura Y. , Niiya T. , Ishibashi T. , Nicolaescu D. , Tsuji H. , Ishikawa J. , Hosono A. , Nakata S. , Okuda S.
Published: May 2007

A method for deriving the length of carbon nanotube (CNT) in field emission arrays is proposed. Unlike the direct method of observation using a microscope, this method gathers information from functional measurements. Electron emission characteristics of CNT’s printed on glass substrate were measured in a diode configuration. The macroscopic part of the voltage field conversion factor β was obtained from the relationship between the slope and intercept of the Fowler-Nordheim plot, and also from modeling of the electrodes. The length of the CNT was derived comparing the two values for β. The estimated length of the CNT agrees with direct measurements.
In situ ion scattering and x-ray photoelectron spectroscopy studies of stability and nanoscale oxidation of single crystal (100) InAs
Authors: Chang Chia-Lin , Shutthanandan Vaithiyalingam , Singhal Subhash C. , Ramanathan Shriram
Published: May 2007

The authors report on the synthesis of clean and smooth surfaces of single crystal InAs (100) by hydrogen molecular cleaning along with in situ studies on the stability of such surfaces against oxide formation. Nanoscale oxidation studies have been performed in detail using in situ nuclear reaction analysis and x-ray photoelectron spectroscopy. Ion channeling studies have been performed to verify atomically smooth surfaces after postcleaning. Stability and kinetic boundaries of cleaned InAs (100) surfaces against oxidation have been experimentally derived. These results are important not only in preparing clean surfaces of InAs but also in understanding fundamentals of oxide/III–V semiconductor interfaces.
Using Vision and Dynamic Touch to Perceive the Affordances of Tools
Authors: Michaels Claire F , Weier Zachary , Harrison Steven J
Published: May 2007

The information that people use to perceive whether a tool is suitable for a certain task depends on what is available at a given time. Visually scanning a tool and wielding it each provide information about the functional attributes of the tool. In experiment 1, we investigated the relative contributions of vision and dynamic touch to perceiving the suitability of various tools for various tasks. The results show that, when both vision and dynamic touch are available, the visual information dominates. When limited to dynamic touch, ratings of suitability are constrained by the inertial properties of the tool, and the inertial properties that are exploited depend on the task. In experiment 2, we asked whether the manner in which a tool is manipulated in exploration depends on the task for which it is being evaluated. The results suggest that tools are manipulated in ways that reflect intentions to perceive particular affordances. Exploratory movements sometimes mimic performatory movements.
Remembering Object Position in the Absence of Vision: Egocentric, Allocentric, and Egocentric Decentred Frames of Reference
Authors: Coluccia Emanuele , Mammarella Irene C , De Beni Rossana , Ittyerah Miriam , Cornoldi Cesare
Published: May 2007

In three experiments we examined whether memory for object locations in the peripersonal space in the absence of vision is affected by the correspondence between encoding and test either of the body position or of the reference point. In particular, the study focuses on the distinction between different spatial representations, by using a paradigm in which participants are asked to relocate objects explored haptically. Three frames of reference were systematically compared. In experiment 1, participants relocated the objects either from the same position of learning by taking as reference their own body (centred egocentric condition) or from a 90° decentred position (allocentric condition). Performance was measured in terms of linear distance errors and angular distance errors. Results revealed that the allocentric condition was more difficult than the centred egocentric condition. In experiment 2, participants performed either the centred egocentric condition or a decentred egocentric condition, in which the body position during the test was the same as at encoding (egocentric) but the frame of reference was based on a point decentred by 90°. The decentred egocentric condition was found to be more difficult than the centred egocentric condition. Finally, in experiment 3, participants performed in the decentred egocentric condition or the allocentric condition. Here, the allocentric condition was found to be more difficult than the decentred egocentric condition. Taken together, the results suggest that also in the peripersonal space and in the absence of vision different frames of reference can be distinguished. In particular, the decentred egocentric condition involves a frame of reference which seems to be neither allocentric nor totally egocentric.
Managing production constraints to the reliability of chickpea (Cicer arietinum L.) within marginal areas of the northern grains region of Australia
Authors: Whish J. P. M. , Castor P. , Carberry P. S.
Published: May 2007

The poor reliability of chickpea yield produced in the marginal (<600 mm rainfall) areas of the northern cropping zone is a constraint to the wide adoption of the crop. Chickpea is a valuable rotation crop and is currently the only viable winter grain legume suitable to this region. This paper uses results from in-crop monitoring and crop simulation, to identify practical management strategies to improve the reliability of chickpea crops in this region. APSIM-Chickpea successfully simulated the commercial yields of chickpea crops monitored during the study. Soil water at sowing and sowing date were identified as key determinants of yield. A ‘rule of thumb’ was derived, which showed that crops sown with a starting plant-available water of ~100 mm at sowing had an 80% probability of producing a better than break-even yield for the majority of the region and this was independent of the soil’s plant-available water capacity or crop sowing date. The probability of accumulating 100 mm of stored water in this western region is 90% following harvest of a May–sown wheat crop. Increased plant population improved crop yields in 60% of years, but this only translated to improved returns in ~50% of those years. The use of these simple management approaches will improve the reliability of chickpea production and ensure that these marginal areas have the option of a viable winter grain legume in their rotations.
Stress response during development predicts fitness in a wild, long lived vertebrate
Authors: Blas J. , Bortolotti G. R. , Tella J. L. , Baos R. , Marchant T. A.
Published: May 2007

Short-term elevation of circulating glucocorticosteroids (GCs) in vertebrates facilitates the adoption of a distinct emergency life history state, which allows individuals to cope with perturbations and recover homeostasis at the expense of temporarily suppressing nonessential activities. Although GC responses are viewed as a major evolutionary mechanism to maximize fitness through stress management, phenotypic variability exists within animal populations, and it remains unclear whether interindividual differences in stress physiology can explain variance in unequivocal components of fitness. We show that the magnitude of the adrenocortical response to a standardized perturbation during development is negatively related to survival and recruitment in a wild population of long lived birds. Our results provide empirical evidence for a link between stress response, not exposure to stressors, and fitness in a vertebrate under natural conditions. Recent studies suggest that variability in the adrenocortical response to stress may be maintained if high and low GC responders represent alternative coping strategies, with differential adaptive value depending on environmental conditions. Increased fitness among low GC responders, having a proactive personality, is predicted under elevated population density and availability of food resources, conditions that characterize our study population.
Mechanism of histone methylation catalyzed by protein lysine methyltransferase SET7/9 and origin of product specificity
Authors: Guo Hao-Bo , Guo Hong
Published: May 2007

Methylation of certain lysine residues in the N-terminal tails of core histone proteins in nucleosome is of fundamental importance in the regulation of chromatin structure and gene expression. Such histone modification is catalyzed by protein lysine methyltransferases (PKMTs). PKMTs contain a conserved SET domain in almost all of the cases and may transfer one to three methyl groups from
S
-adenosyl-
l
-methionine (AdoMet) to the ε-amino group of the target lysine residue. Here, quantum mechanical/molecular mechanical molecular dynamics and free-energy simulations are performed on human PKMT SET7/9 and its mutants to understand two outstanding questions for the reaction catalyzed by PKMTs: the mechanism for deprotonation of positively charged methyl lysine (lysine) and origin of product specificity. The results of the simulations suggest that Tyr-335 (an absolute conserved residue in PKMTs) may play the role as the general base for the deprotonation after dissociation of AdoHcy (
S
-adenosyl-
l
-homocysteine) and before binding of AdoMet. It is shown that conformational changes could bring Y335 to the target methyl lysine (lysine) for proton abstraction. This mechanism provides an explanation why methyl transfers could be catalyzed by PKMTs processively. The free-energy profiles for methyl transfers are reported and analyzed for wild type and certain mutants (Y305F and Y335F) and the active-site interactions that are of importance for the enzyme's function are discussed. The results of the simulations provide important insights into the catalytic process and lead to a better understanding of experimental observations concerning the origin of product specificity for PKMTs.
Vaccination with NY-ESO-1 protein and CpG in Montanide induces integrated antibody/Th1 responses and CD8 T cells through cross-priming
Authors: Valmori Danila , Souleimanian Naira E. , Tosello Valeria , Bhardwaj Nina , Adams Sylvia , O'Neill David , Pavlick Anna , Escalon Juliet B. , Cruz Crystal M. , Angiulli Angelica , Angiulli Francesca , Mears Gregory , Vogel Susan M. , Pan Linda , Jungbluth Achim A. , Hoffmann Eric W. , Venhaus Ralph , Ritter Gerd , Old Lloyd J. , Ayyoub Maha
Published: May 2007

The use of recombinant tumor antigen proteins is a realistic approach for the development of generic cancer vaccines, but the potential of this type of vaccines to induce specific CD8
+
T cell responses, through
in vivo
cross-priming, has remained unclear. In this article, we report that repeated vaccination of cancer patients with recombinant NY-ESO-1 protein, Montanide ISA-51, and CpG ODN 7909, a potent stimulator of B cells and T helper type 1 (Th1)-type immunity, resulted in the early induction of specific integrated CD4
+
Th cells and antibody responses in most vaccinated patients, followed by the development of later CD8
+
T cell responses in a fraction of them. The correlation between antibody and T cell responses, together with the ability of vaccine-induced antibodies to promote
in vitro
cross-presentation of NY-ESO-1 by dendritic cells to vaccine-induced CD8
+
T cells, indicated that elicitation of NY-ESO-1-specific CD8
+
T cell responses by cross-priming
in vivo
was associated with the induction of adequate levels of specific antibodies. Together, our data provide clear evidence of
in vivo
cross-priming of specific cytotoxic T lymphocytes by a recombinant tumor antigen vaccine, underline the importance of specific antibody induction for the cross-priming to occur, and support the use of this type of formulation for the further development of efficient cancer vaccines.
Vesicular ATP Is the Predominant Cause of Intercellular Calcium Waves in Astrocytes
Authors: Bowser David N. , Khakh Baljit S.
Published: May 2007

Brain astrocytes signal to each other and neurons. They use changes in their intracellular calcium levels to trigger release of transmitters into the extracellular space. These can then activate receptors on other nearby astrocytes and trigger a propagated calcium wave that can travel several hundred micrometers over a timescale of seconds. A role for endogenous ATP in calcium wave propagation in hippocampal astrocytes has been suggested, but the mechanisms remain incompletely understood. Here we explored how calcium waves arise and directly tested whether endogenously released ATP contributes to astrocyte calcium wave propagation in hippocampal astrocytes. We find that vesicular ATP is the major, if not the sole, determinant of astrocyte calcium wave propagation over distances between ∼100 and 250 μm, and ∼15 s from the point of wave initiation. These actions of ATP are mediated by P2Y1 receptors. In contrast, metabotropic glutamate receptors and gap junctions do not contribute significantly to calcium wave propagation. Our data suggest that endogenous extracellular astrocytic ATP can signal over broad spatiotemporal scales.