bluuebunny/crossref_metadata_2025 huggingface dataset:
Substance use changes and social role transitions: Proximal developmental effects on ongoing trajectories from late adolescence through early adulthood
Authors: Staff Jeremy , Schulenberg John E. , Maslowsky Julie , Bachman Jerald G. , O'Malley Patrick M. , Maggs Jennifer L. , Johnston Lloyd D.
Published: October 2010

Substance use changes rapidly during late adolescence and early adulthood. This time in the life course is also dense with social role changes, as role changes provide dynamic context for individual developmental change. Using nationally representative, multiwave longitudinal data from age 18 to 28, we examine proximal links between changes in social roles and changes in substance use during the transition to adulthood. We find that changes in family roles, such as marriage, divorce, and parenthood, have clear and consistent associations with changes in substance use. With some notable exceptions, changes in school and work roles have weaker effects on changes in substance use compared to family roles. Changes in socializing (i.e., nights out for fun and recreation) and in religiosity were found to mediate the relationship of social role transitions to substance use. Two time-invariant covariates, socioeconomic background and heavy adolescent substance use, predicted social role status, but did not moderate associations, as within-person links between social roles and substance use were largely equivalent across groups. This paper adds to the cascading effects literature by considering how, within individuals, more proximal variations in school, work, and family roles relate to variations in substance use, and which roles appear to be most influential in precipitating changes in substance use during the transition to adulthood.
Testing a developmental cascade model of adolescent substance use trajectories and young adult adjustment
Authors: Lynne-Landsman Sarah D. , Bradshaw Catherine P. , Ialongo Nicholas S.
Published: October 2010

Developmental models highlight the impact of early risk factors on both the onset and growth of substance use, yet few studies have systematically examined the indirect effects of risk factors across several domains, and at multiple developmental time points, on trajectories of substance use and adult adjustment outcomes (e.g., educational attainment, mental health problems, criminal behavior). The current study used data from a community epidemiologically defined sample of 678 urban, primarily African American youth, followed from first grade through young adulthood (age 21) to test a developmental cascade model of substance use and young adult adjustment outcomes. Drawing upon transactional developmental theories and using growth mixture modeling procedures, we found evidence for a developmental progression from behavioral risk to adjustment problems in the peer context, culminating in a high-risk trajectory of alcohol, cigarette, and marijuana use during adolescence. Substance use trajectory membership was associated with adjustment in adulthood. These findings highlight the developmental significance of early individual and interpersonal risk factors on subsequent risk for substance use and, in turn, young adult adjustment outcomes.
Parents’ experiences of having an asymptomatic child diagnosed with hypertrophic cardiomyopathy through family screening
Authors: Bratt Ewa-Lena , Östman-Smith Ingegerd , Sparud-Lundin Carina , Axelsson B. Åsa
Published: October 2010

Background

Hypertrophic cardiomyopathy is hereditary and the commonest medical cause of sudden death in childhood and adolescence, which is the reason for recommending screening in children with an affected parent. A diagnosis of hypertrophic cardiomyopathy implies lifestyle modifications, restrictions that may bring profound changes to the affected individual and impacts on the whole family.

Objective

To describe parents’ experiences of how the diagnosis of hypertrophic cardiomyopathy in their child affects daily life.

Method

Twelve parents with asymptomatic children diagnosed with hypertrophic cardiomyopathy through family screening were interviewed 12–24 months after the diagnosis. Analysis was conducted with qualitative content analysis.

Results

Parents described the immediate reaction of shock, grief, and injustice but were also grateful that the child was still asymptomatic. The diagnosis caused a significant change in lifestyle for most families due mainly to restrictions of sports activities. Parents had to adapt to the new life and develop strategies to protect their child. Death became a reality causing feelings of vulnerability. Regular medical check-ups and access to the liaison nurse were described as important factors of reassurance.

Conclusions

Parents experienced early diagnosis as positive in a long-term perspective. The main changes perceived were ascribed to lifestyle modifications. Parents with athletic children experienced the lifestyle modifications as more severe. They strived to create a new life where they could feel secure and have faith in the future, and emphasised the need of regular follow-up and support from health care professionals as “mental pain relief”, which helped them achieve a new state of normality.
Reconsidering the syntax of non-canonical negative inversion
Authors: WHITE-SUSTAITA JESSICA
Published: October 2010

Two main hypotheses have been proposed to account for the word order of negative inversion (NI) in varieties of non-canonical English (e.g.Don't nobody else care). An auxiliary inversion analysis argues that the word order is derived via movement of the auxiliary to the left periphery, whereas an existential analysis argues that the word order is an artifact of deletion of the expletive subject, parallelingthere-insertion existential constructions. After reviewing these hypotheses, I provide empirical evidence that neither of these theories adequately explains the peculiarities of NI. I advance a third hypothesis, namely that NI is the result of negative movement to the specifier of NegP, and that this movement is pragmatically motivated by an existential meaning in NI constructions. Syntactically, NI is made possible through the Neg-Criterion (Haegeman & Zanuttini 1991, 1996). This analysis explains problems encountered by prior analyses, and offers a unified analysis for variation in NI across dialects. Finally, I explain cross-dialectal differences in NI by considering the relationship between subject requirements and agreement.
A treasury of Englishes
Authors: MELCHERS GUNNEL
Published: October 2010

This four-volume publication is the second version, envisaged already at the planning of the project, of the monumental overview of World Englishes, first launched in 2004 as the two-volume Handbook of Varieties of English. The individual contributions, each covering the phonology or morphosyntax of a specific variety, are by and large identical in the 2004 and 2008 versions, but the overall structure is different: the more recent, ‘derived’ version is organized according to region, whereas the two 2004 volumes focused on worldwide phonology and morphosyntax respectively. Admittedly, the new version retains the same organization to a degree, in that each regional volume first features the phonology of all its varieties and then morphosyntax. In my view, this is a pity, as a coherent presentation of a variety would clearly have been more reader-friendly, but it would presumably have required a considerable amount of re-editing.
On the Field Evaporation Behavior of Dielectric Materials in Three-Dimensional Atom Probe: A Numeric Simulation
Authors: Oberdorfer Christian , Schmitz Guido
Published: October 2010

As a major improvement in three-dimensional (3D) atom probe, the range of applicable material classes has recently been broadened by the establishment of laser-assisted atom probes (LA-3DAP). Meanwhile, measurements of materials of low conductivity, such as dielectrics, ceramics, and semiconductors, have widely been demonstrated. However, besides different evaporation probabilities, heterogeneous dielectric properties are expected to give rise to additional artifacts in the 3D volume reconstruction on which the method is based. In this article, these conceivable artifacts are discussed based on a numeric simulation of the field evaporation. Sample tips of layer- or precipitate-type geometry are considered. It is demonstrated that dielectric materials tend to behave similarly to metals of reduced critical evaporation field.
Mechanical design and fabrication of a two-blade stripline for the Advanced Photon Source storage ring
Authors: Morrison L. H. , Yao C. Y. , Givens M.
Published: October 2010

The storage ring tune measurement system at the Advanced Photon Source (APS) consists of signal pickup and beam excitation drive striplines. Striplines currently installed in the APS storage ring are of a four-blade (inner conductor) design that serves as a beam diagnostic tool and for transverse and longitudinal tune measurements. A new two-blade stripline was designed for the transverse feedback system and to be used for horizontal beam excitation. In this paper, we discuss its mechanical design, assembly procedure, and construction.
Eltern eines kritisch kranken Kindes – Welche Erwartungen und Wünsche haben sie an das Team der pädiatrischen Intensivstation?
Authors: Spitz-Köberich Christine , Barth Michael , Spirig Rebecca
Published: October 2010

Die Behandlung eines Kindes auf der pädiatrischen Intensivstation stellt für die Eltern eine große physische und psychische Belastung dar. Um besser mit der Situation umgehen zu können, entwickeln sie Erwartungen und Wünsche, die vor allem an das Team der Intensivstation gerichtet sind und deren Erfüllung ihnen wichtig ist. Erwartungen und Wünsche sind stark kulturell beeinflusst. Da es keine Studien aus dem deutschsprachigen Raum gibt, wurde diese qualitative Studie durchgeführt. Anhand eines halbstrukturierten Leitfadens wurden episodische Interviews mit fünf Müttern und zwei Vätern geführt und mit der Methode der qualitativen Inhaltsanalyse nach Mayring ausgewertet. «Die Sorge um das kranke Kind» war für die Eltern von zentraler Bedeutung und bildete die Hauptkategorie. Ihre eigenen Erwartungen und Wünsche spiegelten sich in den sechs Unterkategorien «Das Kind in guten Händen wissen», «Beim Kind sein dürfen», «Miteinbezogen werden», «Fürsorge für sich und das Kind erfahren», «Informiert werden» und «Kontinuität erleben» wider. Diese Ergebnisse stimmen weitestgehend mit denen der internationalen Literatur überein. Lediglich der Wunsch nach einer kontinuierlichen ärztlichen Betreuung und der klaren Aufgabentrennung zwischen Ärzten und Pflegekräften aus Sicht der Eltern wurden bisher nicht beschrieben.
Entwicklungen der deutschsprachigen Pflegewissenschaft im Spiegel der PFLEGE – Veröffentlichung von 1988 – 2007
Authors: Hausner Elke , Halek Margareta , Bartholomeyczik Sabine
Published: October 2010

Bei der PFLEGE handelt es sich um die auflagenstärkste pflegewissenschaftliche Zeitschrift im deutschsprachigen Raum. Durch die Analyse der Artikelstruktur sollen Entwicklungen der deutschsprachigen Pflegewissenschaft aufgezeigt werden. Die vorliegende Veröffentlichung beschreibt die aktualisierten Teilergebnisse einer retrospektiven Studie, die im Rahmen einer Bachelorarbeit der Universität Witten/Herdecke durchgeführt wurde. Dabei konnten 589 Artikel in der Zeit von 1988 – 2007 in die Analyse einbezogen werden. Schwerpunkt der vorliegenden Arbeit ist die Beschreibung und Darstellung der Artikelstruktur insbesondere die verwendeten Forschungsdesigns quantitativer Studien der Zeitschrift PFLEGE. Fast 50 % aller Veröffentlichungen der Zeitschrift PFLEGE (n = 278) stellen Ergebnisse aus empirischer Forschung dar. Der Rest sind «weitere Veröffentlichungen» sowie in zunehmendem Maße Literaturübersichten. Für knapp 80 % (n = 112) aller quantitativen Forschungsfragen wurde ein nichtexperimentelles Design gewählt. Interventionsstudien sind nur zu 20 % (n = 28) zu finden, darunter fünf experimentelle Untersuchungen. Experimentelle Studien (randomised controlled trials) werden in Zukunft weiter an Bedeutung gewinnen. In der PFLEGE spiegelt sich diese Entwicklung noch nicht wider. Weitere bibliometrische Studien sind nötig um herauszufinden, ob deutschsprachige Pflegewissenschaftler/innen tatsächlich selten experimentelle Studien durchführen, oder diese vorrangig in englischsprachigen Fachzeitschriften mit hohem Impact Factor veröffentlichen.
Variability of the semidiurnal internal tides observed on the Timor Shelf
Authors: Katsumata K. , Wijffels S. E. , Steinberg C. R. , Brinkman R.
Published: October 2010

Semidiurnal internal tides drive strong flow variations on the shelf between Timor Island and Australia. The variability of the internal tide over seasonal to interannual time scales is studied using temperature and velocity measurements from 11 moorings, a first attempt for an observational regional synthesis of internal tide behavior. The energy density and flux carried by the semidiurnal tides were calculated from the full water column profile estimated by the Gauss‐Markov fit of the vertical modes incorporating the effects of sloping bottom topography. The estimated energy flux can be interpreted either as generated at and propagating from nearby forcing sites where strong barotropic tides flow over steep topography or as trapped by and circulating around an island topography. The relevant horizontal length scale of the topography is several tens of kilometers, which is the wavelength of the vertical first‐mode internal tides. At some of the moorings with sufficiently long records, seasonal variations of energy density and flux are found with maxima in late summer to winter, which is the same phase as the seasonal variation of the temperature stratification between 100 and 200 m depths. The relationship between the temperature stratification and the internal tide energy density is not linear. For the energy density, the amplitude of the seasonal variation as well as the standard deviation correlates well with the mean value with a correlation coefficient >0.8 and a p value <0.03, but the correlation between the energy density and area‐integrated barotropic tidal forcing is not significant.
Temperature, salinity, and density variability in the central Middle Atlantic Bight
Authors: Castelao Renato , Glenn Scott , Schofield Oscar
Published: October 2010

Four years of sustained glider observations are used to compute the seasonal cycle of hydrographic fields in the central Middle Atlantic Bight (MAB). Results reveal a large phase lag in near bottom temperatures, with peak values occurring in September at the inner shelf, in October at the mid shelf, and in November at the outer shelf. Unlike the northern MAB, the seasonal cycle explains over 70% of the near‐surface salinity variability. At the inner shelf and offshore near the bottom, however, most of the variance is due to pulses in river discharge and to shifts in the position of the shelfbreak front. Cross‐shelf density gradients inshore of the 60‐m isobath are dominated by salinity during winter and spring, with temperature contributing significantly from August to October. This is because bottom waters near the coast are warm due to the deepening of the thermocline during fall, but offshore waters are still influenced by the cold pool. The vertical stratification seasonal variability is also large. Early in the year, stratification is small and entirely due to salinity. By May, salinity still dominates vertical gradients near the coast, but temperature and salinity contribute equally to the density stratification offshore. During summer, stratification is dominated by temperature. Temperature interannual variability was small during the sampling period, but surface salinity was anomalously low by 1.2 psu in summer 2006. The anomaly was due to larger than average discharge from the Hudson River in early summer during a period of strong upwelling favorable winds.
Geodynamic models of Archean continental collision and the formation of mantle lithosphere keels
Authors: Gray Robert , Pysklywec Russell N.
Published: October 2010

The processes responsible for the formation of thick, strong and cold Archean sub‐continental lithospheric mantle (mantle keels) beneath Archean cratons remain elusive. Here, the dynamics of some such processes are studied by forward numerical modeling of the thermo‐mechanical evolution of continental lithosphere undergoing collision and orogenesis under Neoarchean‐like conditions. The numerical experiments illustrate that depending on the composition of the crust and the degree of radioactive heat production (RHP) in the crust, three dominant modes of mantle lithosphere deformation evolve: (1) pure‐shear thickening; (2) imbrication; (3) and a mode best described as underplating. All three modes of deformation result in the thickening and emplacement of plate‐like mantle lithosphere to depths between 200 km and 350 km. The transition from pure‐shear thickening to imbrication is largely dependent on the degree of RHP in the crust, while the transition from the imbrication style to the underplating style is dependent on the composition of the lower crust.
Thermally‐induced chemistry and the Jovian icy satellites: A laboratory study of the formation of sulfur oxyanions
Authors: Loeffler Mark J. , Hudson Reggie L.
Published: October 2010

Laboratory experiments have demonstrated that magnetospheric radiation in the Jovian system drives reaction chemistry in ices at temperatures relevant to Europa and other icy satellites. Here we present new results on thermally‐induced reactions at 50–100 K in solid H2O‐SO2 mixtures, reactions that take place without the need for a high‐radiation environment. We find that H2O and SO2 react to produce sulfur oxyanions, such as bisulfite, that as much as 30% of the SO2 can be consumed through this reaction, and that the products remain in the ice when the temperature is lowered, indicating that these reactions are irreversible. Our results suggest that thermally‐induced reactions can alter the chemistry at temperatures relevant to the icy satellites in the Jovian system.
Model simulation of thermospheric response to recurrent geomagnetic forcing
Authors: Qian Liying , Solomon Stanley C. , Mlynczak Martin G.
Published: October 2010

We assess model capability in simulating thermospheric response to recurrent geomagnetic forcing driven by modulations in the solar wind speed and the interplanetary magnetic field. Neutral density and nitric oxide (NO) cooling rates are simulated for the declining phase of solar cycle 23. The simulated results are compared to neutral density derived from satellite drag and to NO cooling measured by the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) sounding of the atmosphere using broadband emission radiometry (SABER) instrument. Model‐data comparisons show good agreement between the model and the measurements for multiday oscillations, as well as good agreement for longer‐term variations. The simulations demonstrate that the multiday oscillation of density is globally distributed in the upper thermosphere but restricted to high latitudes in the lower thermosphere. The density variation in the upper thermosphere exhibits less latitude dependence than the temperature variation because of the effects of composition changes. Model simulations also show that NO density and temperature play primary roles in the multiday oscillation of NO cooling rates.
Solar wind interaction with Jupiter's magnetosphere
Authors: Delamere P. A. , Bagenal F.
Published: October 2010

We present a review of observations and theories of the dynamics of Jupiter's magnetosphere from Pioneer to New Horizons. We suggest that Jupiter's solar wind–driven magnetospheric flows are due primarily to viscous processes at the magnetopause boundary. Jupiter's magnetopause boundary is determined by a pressure balance between the solar wind dynamic pressure and the magnetospheric high‐β plasma. We discuss how this plasma‐on‐plasma interaction generates solar wind–imposed magnetic stresses that (1) generate the dawn‐dusk asymmetry in plasma flows and magnetic fields, (2) dictate the location of the magnetic x line in the tail, (3) enhance escape of Jovian plasma down the magnetotail, and (4) drive global plasma flows that are consistent with Jupiter's complex polar aurora without the requirement for a persistent region of open flux.
Modeling sea ice production and dense shelf water formation in coastal polynyas around East Antarctica
Authors: Kusahara Kazuya , Hasumi Hiroyasu , Tamura Takeshi
Published: October 2010

Using an ice‐ocean coupled model with fine horizontal resolution around East Antarctica, sea ice production and dense shelf water (DSW) formation in coastal polynyas are investigated. The model reproduces well the locations of coastal polynyas and the high sea ice production there. DSW is formed over the continental shelves under a number of coastal polynyas. A threshold density, beyond which net production of DSW takes place, is largely different among coastal polynyas. The densest and most vigorous DSW formation occurs in the Cape Darnley and Mertz‐Ninnis Glacier polynyas followed by somewhat less but still significant DSW formation in the Prydz‐Barrier and Vincennes polynyas. Assuming mixing of the DSW outflowing across the shelf break with typical Modified Circumpolar Deep Water over the continental slope, the maximum possible formation rate of Antarctic Bottom Water (AABW) is estimated to be 7.58 Sv around East Antarctica between 60°E and 150°E, with the Cape Darnley and Mertz‐Ninnis Glacier polynyas exhibiting the most active formation rates of 2.13 and 1.97 Sv, respectively. From a series of numerical experiments, it is found that the treatment of coastline and grounded icebergs has a large impact on both sea ice production and formation of DSW and AABW.
Growth factor receptor‐bound protein 14: a new modulator of photoreceptor‐specific cyclic‐nucleotide‐gated channel
Authors: Gupta Vivek K , Rajala Ammaji , Daly Roger J , Rajala Raju V S
Published: October 2010

Growth factor receptor‐bound protein 14 (Grb14) is an adaptor protein that is involved in receptor tyrosine kinase signalling. In this study, we report that Grb14 interacts with the rod photoreceptor‐specific cyclic‐nucleotide‐gated channel alpha subunit (CNGA1) and decreases its affinity for cyclic guanosine monophosphate. Channel modulation is controlled by direct binding of the Grb14 Ras‐associating domain with the carboxy‐terminal region of CNGA1. We observed that the channel remains open in Grb14−/− mice that are exposed to light, suggesting that Grb14 is a normal physiological modulator of CNG channel function in vivo.
An Acoustic Study of the Relationships Among Neurologic Disease, Dysarthria Type, and Severity of Dysarthria
Authors: Kim Yunjung , Kent Raymond D. , Weismer Gary
Published: October 2010

Purpose

This study examined acoustic predictors of speech intelligibility in speakers with several types of dysarthria secondary to different diseases and conducted classification analysis solely by acoustic measures according to 3 variables (disease, speech severity, and dysarthria type).

Method

Speech recordings from 107 speakers with dysarthria due to Parkinson’s disease, stroke, traumatic brain injury, and multiple system atrophy were used for acoustic analysis and for perceptual judgment of speech intelligibility. Acoustic analysis included 8 segmental/suprasegmental features: 2nd formant frequency slope, articulation rate, voiceless interval duration, 1st moment analysis for fricatives, vowel space, F0, intensity range, and Pairwise Variability Index.

Results

The results showed that (a) acoustic predictors of speech intelligibility differed slightly across diseases and (b) classification accuracy by dysarthria type was typically worse than by disease type or severity.

Conclusions

These findings were discussed with respect to (a) the relationship between acoustic characteristics and speech intelligibility and (b) dysarthria classification.
Energy Levels and Observed Spectral Lines of Ionized Argon, ArII through ArXVIII
Authors: Saloman E. B.
Published: October 2010

The energy levels and observed spectral lines of ionized argon atoms, in all stages of ionization, have been compiled. Sufficient experimental data were found to generate level and line tables for ArII through ArXV. For ArXVI a mix of experimental and theoretical data were used. Because of the superiority of the theoretical data for ArXVII and ArXVIII, theoretical values are compiled for the energy levels and the lines are calculated from them. Experimental g-factors are included for ArII. A value, either experimental, semiempirical, or theoretical, is included for the ionization energy of each ion.
Polymer brushes with nanoinclusions under shear: A molecular dynamics investigation
Authors: Milchev A. , Dimitrov D. I. , Binder K.
Published: October 2010

We use molecular dynamics simulations with a dissipative particle dynamics thermostat to study the behavior of nanosized inclusions (colloids) in a polymer brush under shear whereby the solvent is explicitly included in the simulation. The brush is described by a bead-spring model for flexible polymer chains, grafted on a solid substrate, while the polymer-soluble nanoparticles in the solution are taken as soft spheres whose diameter is about three times larger than that of the chain segments and the solvent. We find that the brush number density profile, as well as the density profiles of the nanoinclusions and the solvent, remains insensitive to strong shear although the grafted chains tilt in direction of the flow. The thickness of the penetration layer of nanoinclusions, as well as their average concentration in the brush, stays largely unaffected even at the strongest shear. Our result manifests the remarkable robustness of polymer brushes with embedded nanoparticles under high shear which could be of importance for technological applications.
Framework-Type Determination for Zeolite Structures in the Inorganic Crystal Structure Database
Authors: Yang Shujiang , Lach-hab Mohammed , Vaisman Iosif I. , Blaisten-Barojas Estela , Li Xiang , Karen Vicky L.
Published: October 2010

In this work a structural characterization of zeolite crystals is performed by identifying the framework type to which each zeolite belongs. The framework type is assigned for 1433 zeolite database entries in the FIZ/NIST Inorganic Crystal Structure Database (ICSD) populating 95 framework types. These entries correspond to both natural and synthetic zeolites. Each ICSD entry is based on published work containing crystallographic information of the zeolite crystalline structure and some physical and chemical data. Today, the Structure Commission of the International Zeolite Association recognizes crystalline materials as belonging to the “zeolite” family only if they possess one of the approved framework types by the organization. Such information is of fundamental importance for identifying zeolites, for reference, for zeolite standards, for supporting the discovery of new zeolites, and for crystalline substance selection based on application. Unfortunately, framework-type information is not contained in the ICSD records. The long term goal of this work is filling such gap. Although the ICSD contains an extensive collection of zeolites, inclusion of zeolites belonging to the 191 accepted framework types could substantially expand such collection. The structural determination was achieved via several structural analysis methods based on numerical-computer implementations.
Reference Data for the Density and Viscosity of Liquid Copper and Liquid Tin
Authors: Assael Marc J. , Kalyva Agni E. , Antoniadis Konstantinos D. , Michael Banish R. , Egry Ivan , Wu Jiangtao , Kaschnitz Erhard , Wakeham William A.
Published: October 2010

The available experimental data for the density and viscosity of liquid copper and tin have been critically examined with the intention of establishing a density and a viscosity standard. All experimental data have been categorized into primary and secondary data according to the quality of measurement specified by a series of criteria. The proposed standard reference correlations for the density of copper and tin are characterized by standard deviations of 1.3% and 1.0% at the 95% confidence level, respectively. The standard reference correlations for the viscosity of copper and tin are characterized by standard deviations of 6.3% and 20% at the 95% confidence level, respectively.
Controlling vibrational resonance in a multistable system by time delay
Authors: Yang J. H. , Liu X. B.
Published: October 2010

The phenomenon of vibrational resonance in a delayed multistable system that is excited by biharmonic signals is investigated in the present paper. Different from the former theory, the appearance and the disappearance of the vibrational resonance are controlled by adjusting the time delay parameter instead of modulating the amplitude of the high-frequency signal. The motion of the orbit within or between the different potential wells can also be controlled. Furthermore, based on both the methods of numerical simulation and analytical analysis, the behavior of delay-induced multiple vibrational resonance and its mechanism are investigated and discussed. The multiple vibrational resonance, which is quantified by the response amplitude at the low-frequency, is found to be periodic in the delay parameter with two periods, i.e., the periods of the two driven signals. The method used in this paper gives a new way for controlling vibrational resonance in a multistable system.
Gas flows through shallow T-junctions and parallel microchannel networks
Authors: Gat A. D. , Frankel I. , Weihs D.
Published: October 2010

We apply a recent extension of the Hele-Shaw scheme to analyze steady compressible viscous flows through micro T-junctions. The linearity of the problem in terms of an appropriately defined quadratic form of the pressure facilitates the definition of the viscous resistance of the configuration, relating the gas mass-flow rate to entrance and exit conditions. Furthermore, under rather mild restrictions, the performance of complex microchannel networks may be estimated through superposition of the contributions of multiple basic junction elements. This procedure is applied to an optimization model problem of a parallel microchannel network. The analysis and results are readily adaptable to incompressible flows.
New study of the stability and of the spectroscopy of the molecular anions NCO− and CNO−
Authors: Léonard C. , Gritli H. , Chambaud G.
Published: October 2010

Using highly correlated wave functions, the ground and the low lying excited states of the molecular NCO− and CNO− anions have been reinvestigated. The stability of the electronic ground state of the two isomers with respect to dissociation and to electron detachment has been checked along the isomerization pathway. The regions of stability of the excited electronic states have been analyzed and identified and it is shown that only the ground state is stable and the corresponding potential energy surface presents three equilibrium positions. The rovibronic spectroscopy of the X Σ1+ state of both NCO− and CNO− isomers has been determined by a variational approach leading to remarkable agreement with experimental data.
Hydrogen emissions from peripheral plasmas in local island divertor and helical divertor configurations
Authors: Iwamae Atsushi , Sakaue Atsushi , Neshi Nobuhiro , Yanagibayashi Jun , Hasuo Masahiro , Goto Motoshi , Morita Shigeru
Published: October 2010

Superdense core plasmas with a highly peaked electron density profile have been obtained in reduced recycling discharges in the Large Helical Device [O. Motojima et al., Phys. Plasmas 6, 1843 (1999)]. The polarization separation spectroscopy technique has been applied to characterize Hα emissions in the peripheral region of superdense core plasmas. Fitting positions of the high intensity Hα line are located just outside of the last closed flux surface in the local island divertor configuration. In the helical divertor configuration, high intensity emissions are observed around the inner and outer X points and along the divertor legs. In both configurations the hydrogen atoms have an inward velocity along the lines of sight.
Surface stoichiometry and activity control for atomically smooth low dislocation density ZnO and pseudomorphic MgZnO epitaxy on a Zn-polar ZnO substrate by the helicon-wave-excited-plasma sputtering epitaxy method
Authors: Sawai Y. , Hazu K. , Chichibu S. F.
Published: October 2010

The helicon-wave-excited-plasma sputtering (HWPS) method was exemplified to be one of the versatile epitaxial growth techniques for the fabrication of low dislocation density semiconductor epilayers and heterostructures exhibiting atomically smooth surface morphology. For a case study, ZnO homoepitaxy and MgxZn1−xO (x=0.08,0.19) heteroepitaxy on a Zn-polar ZnO substrate were carried out. According to the surface damage-free property, high temperature growth with appropriate stoichiometry control enabled the growth of ZnO homoepitaxial layers exhibiting a smooth surface morphology with 0.26 nm high monolayer atomic steps. Their tilt and twist mosaics reflecting the threading dislocation densities having screw and edge components were comparable to those of the substrate, being under the resolution limit (18 arcsec). The surface morphology and crystal mosaicity of pseudomorphic MgxZn1−xO (x≤0.19) epilayers were quite similar to those of the ZnO underlayer. The luminescence spectra of the ZnO and MgxZn1−xO epilayers at 293 K exhibited a predominant near-band-edge emission and negligible broad emission bands due to deep levels. The results indicate that the growth mode of the HWPS method resembles that of molecular beam epitaxy methods.
Influence of electromechanical effects and wetting layers on band structures of AlN/GaN quantum dots and spin control
Authors: Prabhakar Sanjay , Melnik Roderick
Published: October 2010

In a series of recent papers we demonstrated that coupled electromechanical effects can lead to pronounced contributions in band structure calculations of low dimensional semiconductor nanostructures (LDSNs) such as quantum dots (QDs), wires, and even wells. Some such effects are essentially nonlinear. Both strain and piezoelectric effects have been used as tuning parameters for the optical response of LDSNs in photonics, band gap engineering, and other applications. However, the influence of spin orbit effects in presence of external magnetic field on single and vertically coupled QD has been largely neglected in the literature. The electron spin splitting terms which are coupled to the magnetic field through the Pauli spin matrix in these QDs become important in the design of optoelectronic devices as well as in tailoring properties of QDs in other applications areas. At the same time, single and vertically stacked QDs are coupled with electromagnetic and mechanical fields which become increasingly important in many applications of LDSN-based systems, in particular, where spin splitting energy is important. These externally applied electric and magnetic fields as well as the separation between the vertically coupled QDs can be used as tuning parameters. Indeed, as electromagnetic and elastic effects are often significant in LDSNs, it is reasonable to expect that the externally applied magnetic fields oriented along a direction perpendicular to the plane of two-dimensional electron gas in the QDs may also be used as a tuning parameter in the application of light emitting diodes, logic devices, for example, OR gates, AND gates and others. In this paper, by using the fully coupled model of electroelasticity, we analyze the influence of these effects on optoelectronic properties of QDs. Results are reported for III–V type semiconductors with a major focus given to AlN/GaN based QD systems.
Anomalous hardening under shock compression in (021)-oriented cyclotrimethylene trinitramine single crystals
Authors: Ramos K. J. , Hooks D. E. , Sewell Thomas D. , Cawkwell M. J.
Published: October 2010

We recently proposed that the change observed in the elastic-plastic response of (111)-oriented cyclotrimethylene trinitramine (RDX) crystals under shock compression is caused by an anomalous hardening that is mediated by the homogeneous nucleation of partial dislocation loops with Burgers vector 0.16[010] on (001) {Cawkwell et al., [J. Appl. Phys. 107, 063512 (2010)]}. The orientation dependencies of the (001)[010] slip system suggested that (021)-oriented RDX crystals should also display an anomalous hardening. Molecular dynamics simulations of (021)-oriented RDX crystals confirm that this slip system is activated at a shock pressure 1.34<P≤1.54 GPa. Plate impact experiments on (021)-oriented RDX single crystals show a two-wave elastic-plastic response at 1.0 GPa and an almost overdriven response at 2.25 GPa that is entirely consistent with the theoretical prediction.
Phase transitions in LixAg1−x(Nb0.5Ta0.5)O3 solid solutions
Authors: Khan H. U. , Sterianou I. , Han Y. , Pokorny J. , Reaney I. M.
Published: October 2010

Li x Ag 1 − x ( Nb 0.5 Ta 0.5 ) O 3  (0≤x≤0.25) solid solutions have been fabricated by the mixed oxide method. Compositions with x≤0.15 were single phase perovskite by x-ray diffraction (XRD) and could be indexed using the end member, Ag(Nb0.5Ta0.5)O3 Pbcm cell, 2a,2a,4a (where a is the pseudocubic lattice parameter). For x≥0.20, Li(Nb,Ta)O3 peaks emerged as a second phase. Electron diffraction patterns from the perovskite phase could also be indexed according to the Pbcm cell but there was a systematic decrease in the intensity of {0014}p as Li concentration increased which indicated that the correlation length of cation displacements perpendicular to c decreased from long to short range order. The reduction in correlation length of cation displacements resulted in a convergence of the M1-M2-M3 transitions to give a single broad, frequency dependent maximum at x=0.15. Further increase in Li concentration did not qualitatively affect the temperature dependent dielectric data, consistent with the solubility limit determined by XRD. P-E loops did not show any significant enhancement in switchable polarization in the system with the majority of samples exhibiting a linear dielectric response.
Oscillatory instability of a three-dimensional lid-driven flow in a cube
Authors: Feldman Yuri , Gelfgat Alexander Yu.
Published: October 2010

A series of time-dependent three-dimensional (3D) computations of a lid-driven flow in a cube with no-slip boundaries is performed to find the critical Reynolds number corresponding to the steady-oscillatory transition. The computations are done in a fully coupled pressure-velocity formulation on 1043, 1523, and 2003 stretched grids. Grid-independence of the results is established. It is found that the oscillatory instability of the flow sets in via a subcritical symmetry-breaking Hopf bifurcation at Recr≈1914 with the nondimensional frequency ω=0.575. Three-dimensional patterns in the steady and oscillatory flow regimes are compared with the previously studied two-dimensional configuration and a three-dimensional model with periodic boundary conditions imposed in the spanwise direction.
Single-cell attachment and culture method using a photochemical reaction in a closed microfluidic system
Authors: Jang Kihoon , Xu Yan , Tanaka Yo , Sato Kae , Mawatari Kazuma , Konno Tomohiro , Ishihara Kazuhiko , Kitamori Takehiko
Published: October 2010

Recently, interest in single cell analysis has increased because of its potential for improving our understanding of cellular processes. Single cell operation and attachment is indispensable to realize this task. In this paper, we employed a simple and direct method for single-cell attachment and culture in a closed microchannel. The microchannel surface was modified by applying a nonbiofouling polymer, 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer, and a nitrobenzyl photocleavable linker. Using ultraviolet (UV) light irradiation, the MPC polymer was selectively removed by a photochemical reaction that adjusted the cell adherence inside the microchannel. To obtain the desired single endothelial cell patterning in the microchannel, cell-adhesive regions were controlled by use of round photomasks with diameters of 10, 20, 30, or 50 μm. Single-cell adherence patterns were formed after 12 h of incubation, only when 20 and 30 μm photomasks were used, and the proportions of adherent and nonadherent cells among the entire UV-illuminated areas were 21.3%±0.3% and 7.9%±0.3%, respectively. The frequency of single-cell adherence in the case of the 20 μm photomask was 2.7 times greater than that in the case of the 30 μm photomask. We found that the 20 μm photomask was optimal for the formation of single-cell adherence patterns in the microchannel. This technique can be a powerful tool for analyzing environmental factors like cell-surface and cell-extracellular matrix contact.
Improved thermal stability of gas-phase Mg nanoparticles for hydrogen storage
Authors: Krishnan Gopi , Palasantzas G. , Kooi B. J.
Published: October 2010

This work focuses on improving the thermal stability of Mg nanoparticles (NPs) for use in hydrogen storage. Three ways are investigated that can achieve this goal. (i) Addition of Cu prevents void formation during NP production and reduces the fast evaporation/voiding of Mg during annealing. (ii) Alloying can prevent Mg evaporation: e.g., Mg with Ni forms a thermally stable core/shell (MgNi2/Ni) preventing Mg evaporation during annealing. (iii) Covering Mg NPs with a Ti film leads to suppression of Mg evaporation during vacuum annealing. Indeed, hydrogenation of the Ti/Mg NPs shows formation of the γ-MgH2 phase as for pure Mg NPs.
Localized ultraviolet photoresponse in single bent ZnO micro/nanowires
Authors: Guo Wen , Yang Ya , Qi Junjie , Zhao Jing , Zhang Yue
Published: October 2010

The localized ultraviolet photoresponse in single bent ZnO micro/nanowires bridging two Ohmic contacts has been investigated. The ZnO micro/nanowire has a higher photoresponse sensitivity of about 190% at the bent region (bending strain: about 4%) than that at the straight region (about 50%). The rise and decay time constants are almost the same in the straight and bent regions of the ZnO micro/nanowire. A possible mechanism has been proposed and discussed. The bent ZnO micro/nanowires could be potentially useful for fabricating the coupled piezoelectric and optoelectronic nanodevices.
Electron band alignment between (100)InP and atomic-layer deposited Al2O3
Authors: Chou Hsing-Yi , Afanas’ev V. V. , Stesmans A. , Lin H. C. , Hurley P. K. , Newcomb S. B.
Published: October 2010

Energy barriers at interfaces of (100)InP with atomic-layer deposited Al2O3 are determined using internal photoemission of electrons. The barrier height between the top of the InP valence band and bottom of the alumina conduction band is found to be 4.05±0.10 eV corresponding to a conduction band offset of 2.7 eV. An interlayer associated with the oxidation of InP may result in a lower barrier for electron injection potentially leading to charge instability of the insulating stack. A wide-gap P-rich interlayer has a potential to reduce this degrading effect as compared to In-rich oxides.
Obama announces reforms to simplify and reduce export controls
Authors: Kramer David
Published: October 2010

Universities welcome efforts to scale back federal controls over campus research by foreign nationals.
US astronomy community sets plan to fit tight times
Authors: Feder Toni
Published: October 2010

Balance, flexibility, and broad science mark the latest decadal survey. And, nitpicking aside, the survey is finding wide endorsement among astronomers and astrophysicists.
Flavor oscillation may be different in neutrinos and antineutrinos
Authors: Schwarzschild Bertram
Published: October 2010

An unanticipated violation of matter-antimatter symmetry could reconcile conflicting experimental evidence about the possible existence of sterile neutrinos.
A First Generation Chemoenzymatic Synthesis of (+)-Galanthamine
Authors: Banwell Martin G. , Ma Xinghua , Karunaratne Ochitha P. , Willis Anthony C.
Published: October 2010

A total synthesis of (+)-galanthamine [(+)-1] has been achieved using the readily available and enantiomerically pure metabolite 2 as starting material. The quaternary carbon centre (C8a) associated with target 1 was constructed using the Eschenmoser–Claisen rearrangement reaction.
An Expeditious Synthesis of Iminosugars
Authors: Gandy Michael N. , Piggott Matthew J. , Stubbs Keith A.
Published: October 2010

A short and expedient synthesis of the potent glycosidase inhibitors, 1-deoxynojirimycin, miglitol, miglustat, 1-deoxymannojirimycin, and 1-deoxygalactonojirimycin is presented.
Differential regulation of igf1 and igf1r mRNA levels in the two hepatic lobes following intrauterine growth restriction and its treatment with intra-amniotic insulin-like growth factor-1 in ovine fetuses
Authors: Darp Revati A. , de Boo Hendrina A. , Phua Hui Hui , Oliver Mark H. , Derraik José G. B. , Harding Jane E. , Bloomfield Frank H.
Published: October 2010

Intrauterine growth restriction (IUGR) has life-long health implications, yet there is no effective prenatal treatment. Daily intra-amniotic administration of insulin-like growth factor (IGF)-1 to IUGR fetal sheep improves fetal gut maturation but suppresses hepatic igf1 gene expression. Fetal hepatic blood supply is regulated, in part, by shunting of oxygen- and nutrient-rich umbilical venous blood through the ductus venosus, with the left hepatic lobe predominantly supplied by umbilical venous blood and the right hepatic lobe predominantly supplied by the portal circulation. We hypothesised that: (1) once-weekly intra-amniotic IGF-1 treatment of IUGR would be effective in promoting gut maturation; and (2) IUGR and its treatment with intra-amniotic IGF-1 would differentially affect igf1 and igf1r mRNA expression in the two hepatic lobes. IUGR fetuses received 360 µg IGF-1 or saline intra-amniotically once weekly from 110 until 131 days gestation. Treatment of IUGR fetuses with IGF-1 reversed impaired gut growth. In unembolised, untreated control fetuses, igf1 mRNA levels were 19% lower in the right hepatic lobe than in the left; in IUGR fetuses, igf1 and igf1r mRNA levels were sixfold higher in the right lobe. IGF-1 treatment reduced igf1 and igf1r mRNA levels in both lobes compared with IUGR fetuses. Thus, weekly intra-amniotic IGF-1 treatment, a clinically feasible approach, reverses the impaired gut development seen in IUGR. Furthermore, igf1 and igf1r mRNA levels are differentially expressed in the two hepatic lobes and relative expression in the two lobes is altered by both IUGR and intra-amniotic IGF-1 treatment.