bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative effectiveness of two doses versus three doses of hepatitis A vaccine in human immunodeficiency virus–infected and -uninfected men who have sex with men
Authors: Tseng Yu-Tzu , Chang Sui-Yuan , Liu Wen-Chun , Sun Hsin-Yun , Wu Cheng-Hsin , Wu Pei-Ying , Lu Ching-Lan , Hung Chien-Ching , Chang Shan-Chwen
Published: December 2012

The purpose of this prospective cohort study was to compare the serologic response between human immunodeficiency virus (HIV)-infected men who have sex with men (MSM) receiving two and three doses of hepatitis A virus (HAV) vaccine and HIV-uninfected MSM receiving two doses of HAV vaccine. Between June 2009 and December 2010, 582 MSM aged 18 to 40 years who were seronegative for HAV were enrolled in the study. HIV-infected MSM received either two doses of HAV vaccine (1,440 enzyme-linked immunosorbent assay units) (n = 140) with the second dose given at week 24 or three doses (n = 225) with the second and third dose given at weeks 4 and 24, respectively, while HIV-uninfected MSM (n = 217) received two doses. The primary endpoint was seroconversion at week 48. The geometric mean concentration (GMC) of anti-HAV antibody was determined at weeks 48 and 72. At week 48, the seroconversion rate was 75.7%, 77.8%, and 88.5% in intention-to-treat analysis for two-dose HIV-infected, three-dose HIV-infected, and two-dose HIV-uninfected MSM, respectively. The GMC of anti-HAV antibody at week 48 for three-dose HIV-infected MSM (2.29 ± 0.73 log10 mIU/mL) was significantly higher than that for two-dose HIV-infected MSM (1.94 ± 0.66;

P

< 0.01), but was lower than HIV-uninfected MSM (2.49 ± 0.42;

P

< 0.01). Multivariate analysis revealed higher CD4 counts (adjusted odds ratio [AOR] for per 50 cells/μL increase, 1.13; 95% confidence interval [CI], 1.05-1.21) and undetectable plasma HIV RNA load (AOR, 1.90; 95% CI, 1.10-3.28) before HAV vaccination were predictive of seroconversion in HIV-infected patients.

Conclusion:

Serologic response rate to three and two doses of HAV vaccine was similar in HIV-infected MSM, which was lower than that in HIV-uninfected MSM receiving two doses. HAV vaccination in HIV-infected patients with a higher CD4 count and suppression of HIV replication increased the seroconversion rate.
Alkaline hydrolysis of ethiofencarb: Kinetic study and mechanism degradation
Authors: Ouertani Randa , El Atrache Latifa Latrous , Hamida Nejib Ben
Published: December 2012

The present paper deals with the hydrolysis of ethiofencarb [2‐ethylthiomethyl(phenyl)‐N‐methylcarbamate] in alkaline solution. The reaction kinetics has been investigated using spectrophotometric and liquid chromatographic techniques. The rate constants were determined following a proposed first‐order kinetic model. The positive activation entropy Δ S≠ = +100.07 J mol−1 K−1 and the absence of general basic catalysis indicated an E1cB hydrolytic mechanism, involving the formation of methyl isocyanate. This result was confirmed by the fact that ethiofencarb fits well into Brönsted and Hammett lines, obtained for a series of substituted N‐methylcarbamate whose decomposition in aqueous media was established to follow an E1cB mechanism. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 118–124, 2013
Synthesis and Characterization of Polysulfone/POSS Hybrid Networks by Photoinduced Crosslinking Polymerization
Authors: Dizman Cemil , Uyar Tamer , Tasdelen Mehmet Atilla , Yagci Yusuf
Published: December 2012

Crosslinked polysulfone/polyhedral oligomeric silsesquioxane (POSS) hybrid networks were synthesized in this work by photoinduced copolymerization of polysulfone dimethacrylate (PSU‐DMA) and multifunctional POSS‐methacrylamide (POSS‐MAAm) with various feed ratios. The morphology of the nanocomposites was investigated by transmission electron microscopy (TEM), which suggests the random dispersion of POSS in the PSU matrix without macroscopic agglomeration. Thermogravimetric analysis results confirmed that the thermal stability and char yield of PSU‐DMA/POSS‐MAAm nanocomposites increased with the increase of POSS loading. Enhanced glass transition temperatures and storage modulus of the networks were observed to be higher than its precursor polymer.
Increased Prostaglandin Response to Oxytocin in Ewes Fed a Diet High in Omega‐6 Polyunsaturated Fatty Acids
Authors: Gulliver Catherine E. , Friend Michael A. , King Belinda J. , Robertson Susan M. , Wilkins John F. , Clayton Edward H.
Published: December 2012

Diets high in omega‐6 polyunsaturated fatty acids (n‐6) are associated with increased prostaglandin F2α (PGF2α) synthesis in cattle, however, the specific effects on the potential prostaglandin response to an oxytocin challenge in sheep have not been reported. The aim of the current study was to determine whether oxytocin‐stimulated PGF2α was significantly increased when ewes were fed a diet high in n‐6 compared with a control diet low in n‐6. Merino x Border Leicester ewes (n = 30) received one of two dietary treatments, either high in n‐6 (70 % oat grain) or low in n‐6 (control diet, 100 % cereal/legume silage). Ewes consumed the diets for 44 days prior to two consecutive oxytocin challenges. Plasma n‐6 and PGF2α metabolite (PGFM) concentrations following oxytocin challenge were greater (P < 0.05) when ewes were fed a diet high in n‐6 compared with the control diet. A higher availability of n‐6 may have lead to an increased in vivo synthesis of PGF2α, however, further research is required to determine the exact mechanisms involved.
Emerging themes in the computational design of novel enzymes and protein–protein interfaces
Authors: Khare Sagar D. , Fleishman Sarel J.
Published: December 2012

Recent years have seen the first applications of computational protein design to generate novel catalysts, binding pairs of proteins, protein inhibitors, and large oligomeric assemblies. At their core these methods rely on a similar hybrid energy function, composed of physics‐based and database‐derived terms, while different sequence and conformational sampling approaches are used for each design category. Although these are first steps for the computational design of novel function, crystal structures and biochemical characterization already point out where success and failure are likely in the application of protein design. Contrasting failed and successful design attempts has been used to diagnose deficiencies in the approaches and in the underlying hybrid energy function. In this manner, design provides an inherent mechanism by which crucial information is obtained on pressing areas where focused efforts to improve methods are needed. Of the successful designs, many feature pre‐organized sites that are poised to perform their intended function, and improvements often result from disfavoring alternative functionally suboptimal states. These rapid developments and fundamental insights obtained thus far promise to make computational design of novel molecular function general, robust, and routine.
Insights into Holocene megafauna survival and extinction in southeastern Brazil from new AMS 14C dates
Authors: Hubbe Alex , Hubbe Mark , Karmann Ivo , Cruz Francisco W. , Neves Walter A.
Published: December 2012

The extinction of late Quaternary megafauna in South America has been extensively debated in past decades. The majority of the hypotheses explaining this phenomenon argue that the extinction was the result of human activities, environmental changes, or even synergism between the two. Although still limited, a good chronological framework is imperative to discuss the plausibility of the available hypotheses. Here we present six new direct AMS 14C radiocarbon dates from the state of São Paulo (Brazil) to further characterize the chronological distribution of extinct fauna in this part of South America. The new dates make evident that ground sloths, toxodonts, and saber-toothed cats lived in the region around the Pleistocene/Holocene transition, and in agreement with previous studies, also suggest an early Holocene survival for the ground sloth Catonyx cuvieri. Taken together with local paleoclimatic and archaeological data, the new dates do not support hunting or indirect human activities as a major cause for megafauna extinction. Although more data are required, parsimony suggests that climatic changes played a major role in this extinction event.
Clustering of ions at atomic dimensions in quantum plasmas
Authors: SHUKLA PADMA K. , ELIASSON BENGT
Published: December 2012

By means of particle simulations of the equations of motion for ions interacting among themselves under the influence of newly discovered Shukla–Eliasson attractive force (SEAF) in a dense quantum plasma, we demonstrate that the SEAF can bring ions closer at atomic dimensions. We present simulation results of the dynamics of an ensemble of ions in the presence of the SEAF without and with confining external potentials and collisions between ions and degenerate electrons. Our particle simulations reveal that under the SEAF, ions attract each other, come closer, and form ionic clusters in the bath of degenerate electrons that shield ions. Furthermore, an external confining potential produces robust ion clusters that can have cigar- and ball-like shapes, which remain stable when the confining potential is removed. The stability of ion clusters is discussed. Our results may have applications to solid density plasmas (density exceeding 1023 per cm3), where the electrons will be degenerate and quantum forces due to the electron recoil effect caused by the overlapping of electron wave functions and electron tunneling through the Bohm potential, electron-exchange and electron-exchange and electron correlations associated with electron-1/2 spin effect, and the quantum statistical pressure of the degenerate electrons play a decisive role.
Parents' preferred care-givers in rural China: gender, migration and intergenerational exchanges
Authors: CONG ZHEN , SILVERSTEIN MERRIL
Published: December 2012

This study examines how intergenerational exchanges affect elders' choice of preferred care-givers in the case of sickness among adult children in rural China. The sample derived from a four-wave longitudinal study in Anhui Province, China, based on which we constructed three time intervals (i.e.2001–2003, 2003–2006 and 2006–2009) and stacked them. Our working sample included 10,181 observations from these three stacked intervals, representing 4,927 children with 1,170 elder parents. We used fixed-effects logistic regression to predict elders' favouritism among their children. Results show that those children who received more help with grandchild care from parents, who provided instrumental support to parents and whose spouses provided instrumental support to parents were more likely to be named the preferred care-givers. On average, parents favoured sons. For mothers, this favouritism was completely explained by proximity and intergenerational exchanges, and even reversed under certain circumstances. For fathers, this favouritism of sons was partially explained by proximity and intergenerational exchanges. Migrant children were less likely to be preferred care-givers. This effect was moderated by elder parents' help with caring for grandchildren. Particularly, mothers favoured daughters over sons if the above moderation effect was considered. We discuss these findings in the context of social changes including increased importance of daughters in elder parents' support networks and the large-scale rural to urban migration.
COST-UTILITY ANALYSIS OF NT-PROBNP-GUIDED MULTIDISCIPLINARY CARE IN CHRONIC HEART FAILURE
Authors: Moertl Deddo , Steiner Sabine , Coyle Doug , Berger Rudolf
Published: December 2012

Objectives: A recent randomized, controlled trial in chronic heart failure patients showed that NT-proBNP-guided, intensive patient management (BMC) on top of multidisciplinary care reduced all-cause mortality and heart failure hospitalizations compared with multidisciplinary care (MC) or usual care (UC). We now performed a cost-utility analysis of these interventions from a payer's perspective.

Methods: Costs related to hospitalizations, ambulatory physician and nurse visits, and NT-proBNP testing for the three management strategies were acquired for both Austria (€) and Canada ($) and combined with the survival and quality of life data from the clinical trial for cost-effectiveness analysis. Data on long-term survival, costs, and quality-adjusted life-years (QALY) were extrapolated for a 20-year time horizon using a Markov model, which simulated the progression of disease through beta-blocker use, hospitalizations, and mortality.

Results: BMC was the most cost-effective strategy as it was dominant (cost-saving with improved health outcome) over both MC and UC based on both Austrian and Canadian costs. Incremental cost-effectiveness ratios for MC relative to UC were €3,746 and $5,554 per QALY gained for Austrian and Canadian costs, respectively. The probabilities for BMC being the most cost-effective strategy were 92 percent at a threshold value of Austrian €40,000 and 93 percent at a threshold value of Canadian $50,000.

Conclusions: NT-proBNP-guided, intensive HF patient management in addition to multidisciplinary care not only reduces death and hospitalization but also proves to be cost-effective.
Past participles of strong verbs in Jutland Danish: A real-time study of regionalization and standardization
Authors: Jensen Torben Juel , Maegaard Marie
Published: December 2012

The article presents a real-time study of standardization and regionalization processes with respect to the use of past participles of strong verbs in the western part of Denmark. Analyses of a large corpus of recordings of informants from two localities show that the use of the dialectalenform of the past participle suffix has been in decline during the last 30 years. Theenforms are replaced by three other forms, one of which is (partly) dialectal, one regional and one standard Danish. The study indicates that a regionalization process has taken place prior to the time period studied, but that it has now been overtaken by a Copenhagen-based standardization process. The study also shows interesting differences between the two localities, arguably due to the geographical location and size, and to the status of the different participle forms in the traditional local dialects.
Quantification of ikaite in Antarctic sea ice
Authors: Fischer Michael , Thomas David N. , Krell Andreas , Nehrke Gernot , Göttlicher Jörg , Norman Louiza , Meiners Klaus M. , Riaux-Gobin Catherine , Dieckmann Gerhard S.
Published: December 2012

Calcium carbonate precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice, although it is hypothesized that high quantities of dissolved organic matter and/or phosphate (common in sea ice) may inhibit its formation. In this quantitative study of hydrous calcium carbonate as ikaite, sea ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during two expeditions, one in the East Antarctic sector and the other off Terre Adélie. Samples were analysed for CaCO3, salinity, dissolved organic carbon/nitrogen, inorganic phosphate, and total alkalinity. No relationship between these parameters and CaCO3 precipitation was evident. Ikaite was found mostly in the uppermost layers of sea ice with maximum concentrations of up to 126 mg ikaite per litre melted sea ice being measured, although both the temporal and horizontal spatial distributions of ikaite were highly heterogeneous. The precipitate was also found in the snow on top of the sea ice at some of the sampling locations.
Optimal Packings of Hamilton Cycles in Graphs of High Minimum Degree
Authors: KÜHN DANIELA , LAPINSKAS JOHN , OSTHUS DERYK
Published: December 2012

We study the number of edge-disjoint Hamilton cycles one can guarantee in a sufficiently large graph G on n vertices with minimum degree δ=(1/2+α)n. For any constant α>0, we give an optimal answer in the following sense: let regeven(n,δ) denote the degree of the largest even-regular spanning subgraph one can guarantee in a graph on n vertices with minimum degree δ. Then the number of edge-disjoint Hamilton cycles we find equals regeven(n,δ)/2. The value of regeven(n,δ) is known for infinitely many values of n and δ. We also extend our results to graphs G of minimum degree δ ≥ n/2, unless G is close to the extremal constructions for Dirac's theorem. Our proof relies on a recent and very general result of Kühn and Osthus on Hamilton decomposition of robustly expanding regular graphs.
Sisters of early modern confraternities in a small town in the Southern Netherlands (Aalst)
Authors: DECRAENE ELLEN
Published: December 2012

This article analyses female agency within the religious confraternities active in an early modern town in the Southern Netherlands in order to gain an insight into women's positions within a (semi-)public urban network and thus beyond the household. The analysis suggests that confraternities did not provide women with opportunities to develop a significant public role within the town. Nonetheless, while there is little evidence that early modern religious confraternities functioned as social networks, female agency on the religious level of confraternal life did exist. It is argued that many of these women were active agents in their own spiritual lives.
Fighting against the Moral Agenda of Zapatero's Socialist Government (2004–2011): The Spanish Catholic Church as a Political Contender
Authors: Fernández Susana Aguilar
Published: December 2012

Even though not all European churches can be ascribed a political profile, moral issues have unleashed the protest of some of them alongside Christian-inspired groups and advocacy coalitions. Mobilization against these issues is not surprising in democracy but the different role that churches might play is. Unlike other European churches, the Spanish Catholic Church has acted as a political contender under Zapatero's rule (2004–2011). The new Socialist agenda, with its emphasis on morally-liberal reforms, has triggered a protest in which the church has invested significant resources and helped mobilize the more Conservative quarters of the Catholic society. This adversarial role is distinctive but not unique: the Italian and Polish churches have also opted for confrontational strategies in the face of similar challenges. However, the Spanish case is most relevant because, unlike other predominantly Catholic societies (Italy, Portugal, Ireland, and Poland), it has experienced a most profound and fastest secularization process. Confrontation can then be explained by the supply (a well-endowed Church that enjoys a privileged relationship with a non-confessional state) and not by the demand.
Members of native coral microbiota inhibit glycosidases and thwart colonization of coral mucus by an opportunistic pathogen
Authors: Krediet Cory J , Ritchie Kim B , Alagely Ali , Teplitski Max
Published: December 2012

The outcome of the interactions between native commensal microorganisms and opportunistic pathogens is crucial to the health of the coral holobiont. During the establishment within the coral surface mucus layer, opportunistic pathogens, including a white pox pathogen Serratia marcescens PDL100, compete with native bacteria for available nutrients. Both commensals and pathogens employ glycosidases and N-acetyl-glucosaminidase to utilize components of coral mucus. This study tested the hypothesis that specific glycosidases were critical for the growth of S. marcescens on mucus and that their inhibition by native coral microbiota reduces fitness of the pathogen. Consistent with this hypothesis, a S. marcescens transposon mutant with reduced glycosidase and N-acetyl-glucosaminidase activities was unable to compete with the wild type on the mucus of the host coral Acropora palmata, although it was at least as competitive as the wild type on a minimal medium with glycerol and casamino acids. Virulence of the mutant was modestly reduced in the Aiptasia model. A survey revealed that ∼8% of culturable coral commensal bacteria have the ability to inhibit glycosidases in the pathogen. A small molecular weight, ethanol-soluble substance(s) produced by the coral commensal Exiguobacterium sp. was capable of the inhibition of the induction of catabolic enzymes in S. marcescens. This inhibition was in part responsible for the 10–100-fold reduction in the ability of the pathogen to grow on coral mucus. These results provide insight into potential mechanisms of commensal interference with early colonization and infection behaviors in opportunistic pathogens and highlight an important function for the native microbiota in coral health.
Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique
Authors: Sayer Robert A. , Piekos Edward S. , Phinney Leslie M.
Published: December 2012

Accurate knowledge of thermophysical properties is needed to predict and optimize the thermal performance of microsystems. Thermal conductivity is experimentally determined by measuring quantities such as voltage or temperature and then inferring a thermal conductivity from a thermal model. Thermal models used for data analysis contain inherent assumptions, and the resultant thermal conductivity value is sensitive to how well the actual experimental conditions match the model assumptions. In this paper, a modified data analysis procedure for the steady state Joule heating technique is presented that accounts for bond pad effects including thermal resistance, electrical resistance, and Joule heating. This new data analysis method is used to determine the thermal conductivity of polycrystalline silicon (polysilicon) microbridges fabricated using the Sandia National Laboratories SUMMiT V™ micromachining process over the temperature range of 77–350 K, with the value at 300 K being 71.7 ± 1.5 W/(m K). It is shown that making measurements on beams of multiple lengths is useful, if not essential, for inferring the correct thermal conductivity from steady state Joule heating measurements.
Transport in the random Kronig-Penney model
Authors: Drabkin Maxim , Kirsch Werner , Schulz-Baldes Hermann
Published: December 2012

The Kronig-Penney model with random Dirac potentials on the lattice \documentclass[12pt]{minimal}\begin{document}${\mathbb {Z}}$\end{document}Z has critical energies at which the Lyapunov exponent vanishes and the density of states has a van Hove singularity. This leads to a non-trivial quantum diffusion even though the spectrum is known to be pure-point.
Mechanical behavior of MoS2 nanotubes under compression, tension, and torsion from molecular dynamics simulations
Authors: Bucholz Eric W. , Sinnott Susan B.
Published: December 2012

The mechanical behavior of different types of single-walled and double-walled MoS2 nanotubes when subjected to external compressive, tensile, and torsional loading is investigated using classical molecular dynamics simulations. The forces on the atoms are determined using a reactive empirical bond-order potential parameterized for Mo-S systems. The simulations report on the elastic properties of the different MoS2 nanotube systems as well as the interrelationships between the buckling behavior and the structural parameters of the nanotubes, such as length, diameter, chirality, and number of walls. The simulations predict that the most important factor influencing mechanical response is the number of walls present and, to a lesser extent, the diameters of the nanotubes, with the other structural parameters predicted to have little effect on the results over the range investigated. These findings are consistent with reported density functional theory calculations and experimental data for WS2 and MoS2 nanotubes.
Compact metal probes: A solution for atomic force microscopy based tip-enhanced Raman spectroscopy
Authors: Rodriguez R. D. , Sheremet E. , Müller S. , Gordan O. D. , Villabona A. , Schulze S. , Hietschold M. , Zahn D. R. T.
Published: December 2012

There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.
Topological insulator Bi2Se3 thin films as an alternative channel material in metal-oxide-semiconductor field-effect transistors
Authors: Chang Jiwon , Register Leonard F. , Banerjee Sanjay K.
Published: December 2012

Three-dimensional (3-D) topological insulators (TIs) are characterized by the presence of metallic surface states and a bulk band gap. Recently, theoretical and experimental studies have shown an induced gap in the surface state bands of TI thin films. The gap results from interaction of conduction band and valence band surface states from the opposite surfaces of a thin film, and its size is determined by the film thickness. This gap formation could open the possibility of thin-film TI-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Here we explore the performance of MOSFETs based on TI thin films, specifically Bi2Se3, using quantum ballistic transport simulations with the tight-binding Hamiltonian in the atomic orbital basis. Our simulations indicate that Bi2Se3 MOSFET will be vulnerable to short-channel effects due to the high relative dielectric constant of Bi2Se3 (∼100) despite its expected excellent electrostatic integrity inherent in a two-dimensional system, and will have other limitations as compared to silicon–based MOSFETs. However, Bi2Se3 MOSFETs, and presumably other TI-based MOSFETs, appear to provide reasonable performance that perhaps could provide novel device opportunities when combined with novel TI properties such as spin-polarized surface states.
Oscillatory characteristics of carbon nanotubes inside carbon nanotube bundles
Authors: Ansari R. , Alipour A. , Sadeghi F.
Published: December 2012

This article presents a comprehensive study on the mechanics of carbon nanotubes (CNTs) oscillating in CNT bundles. Using the continuum approximation along with Lennard-Jones (LJ) potential function, new semi-analytical expressions in terms of double integrals are presented to evaluate van der Waals (vdW) potential energy and interaction force upon which the equation of motion is directly solved. The obtained potential expression enables one to arrive at a new semi-analytical formula for the exact evaluation of oscillation frequency. Also, an algebraic frequency formula is extracted on the basis of the simplifying assumption of constant vdW force. Based on the present expressions, a thorough study on various aspects of operating frequencies under different system parameters is given, which permits fresh insight into the problem. The strong dependence of oscillation frequency on system parameters, such as the extrusion distance and initial velocity of the core as initial conditions for the motion is indicated. Interestingly, a specific initial velocity is found at which the oscillation frequency is independent of the core length. In addition, a relation between this specific initial velocity and the escape velocity is disclosed.
Evolution of subcritical nuclei in nitrogen-alloyed Ge2Sb2Te5
Authors: Darmawikarta Kristof , Raoux Simone , Tchoulfian Pierre , Li Tian , Abelson John R. , Bishop Stephen G.
Published: December 2012

We analyze the evolution of subcritical nuclei as a function of nitrogen alloying and thermal annealing in the amorphous phase change material Ge2Sb2Te5. The existence of subcritical nuclei is inferred through measurement of the nucleation time in pulsed laser annealing, and is detected more directly using fluctuation transmission electron microscopy measurements that are sensitive to topological order on the nanoscale. In samples that are pre-annealed before crystallization experiments, the nanoscale order consistently increases and the nucleation times consistently decrease, in agreement with the interpretation that the nanoscale order corresponds to a population of subcritical nuclei that ripens upon annealing. However, this correlation is less obvious in as-deposited samples across a range of nitrogen contents: The quantity of nanoscale order diminishes only slightly with increased nitrogen alloying, whereas the nucleation times increase by nearly two orders of magnitude. We therefore interpret that nitrogen must affect either the critical size in order for a nucleus to be stable (the thermodynamics) or the rate at which nucleation and growth take place (the kinetics).
A light scattering study of non equilibrium fluctuations in liquid mixtures to measure the Soret and mass diffusion coefficient
Authors: Croccolo F. , Bataller H. , Scheffold F.
Published: December 2012

We use dynamic near field scattering to measure the dynamics of concentration non equilibrium fluctuations at the steady-state of Soret separation. The analysis reveals that above a threshold wave vector qc, the dynamics is governed by diffusion while at smaller wave vectors, gravity dominates. From the measurements, we extract both the mass diffusion and the Soret coefficients. Comparing our results with literature data, we find good agreement confirming that the proposed experimental technique can be considered a sound approach for the study of thermodiffusion processes.
Experimental simulation of the salt gradient solar pond stability
Authors: Karim Choubani , Mohamed Jomâa Safi
Published: December 2012

In order to design and analyse natural or artificial system, where instable stratified layer occurs (such as solar pound and storage tanks), understanding of double diffusive behaviour is necessary. When an initially isothermal, salt stratified-system is heated uniformly from below, a convecting, growing layer is first formed whose sizes depend on the stabilizing salinity distribution. A quantitative description of such problem showed that a convective motion first produces layer at the bottom. This layer, separated by an oscillatory interface, continues to deepen with time until achieving a critical depth. The mechanisms responsible for the growth of the first mixed layer are poorly understood until now. A laboratory study is made to well understand the mechanism of transfer in an instable stratified system. A transparent cavity with free surface is filled with stratified-salt water and it is heated from below at constant temperature. The convective motion is visualized by (a) shadowgraph to obtain more information on density exchange through the interface and (b) particle image velocimetry to measure the time evolution of speed fields.
Aggregation of rod-like polyelectrolyte chains in the presence of monovalent counterions
Authors: Varghese Anoop , Rajesh R. , Vemparala Satyavani
Published: December 2012

Using molecular dynamics simulations, it is demonstrated that monovalent counterions can induce aggregation of similarly charged rod-like polyelectrolyte chains. The critical value of the linear charge density for aggregation is shown to be close to the critical value for the extended-collapsed transition of a single flexible polyelectrolyte chain, and decreases with increasing valency of the counterions. The potential of mean force along the center of mass reaction coordinate between two similarly charged rod-like polyelectrolytes is shown to develop an attractive well for large linear charge densities. In the attractive regime, the angular distribution of the condensed counterions is no longer isotropic.
An ultrafast angle-resolved photoemission apparatus for measuring complex materials
Authors: Smallwood Christopher L. , Jozwiak Christopher , Zhang Wentao , Lanzara Alessandra
Published: December 2012

We present technical specifications for a high resolution time- and angle-resolved photoemission spectroscopy setup based on a hemispherical electron analyzer and cavity-dumped solid state Ti:sapphire laser used to generate pump and probe beams, respectively, at 1.48 and 5.93 eV. The pulse repetition rate can be tuned from 209 Hz to 54.3 MHz. Under typical operating settings the system has an overall energy resolution of 23 meV, an overall momentum resolution of 0.003 Å−1, and an overall time resolution of 310 fs. We illustrate the system capabilities with representative data on the cuprate superconductor Bi2Sr2CaCu2O8+δ. The descriptions and analyses presented here will inform new developments in ultrafast electron spectroscopy.
The impulse response of a high-speed jet forced with localized arc filament plasma actuators
Authors: Sinha Aniruddha , Alkandry Hind , Kearney-Fischer Martin , Samimy Mo , Colonius Tim
Published: December 2012

We present experimental and theoretical analyses of the response of high-speed, high-Reynolds-number, round jets to impulsive forcing with arc-filament-plasma actuators. The impulse response is obtained with forcing Strouhal numbers, based on the nozzle exit diameter and exit center line velocity, less than 0.1. The resulting phase-averaged near-field pressure signature displays a compact wave with a positive peak preceding a negative one, indicative of a large scale structure in the shear layer of the jet. Scaling laws derived by operating the jet at four subsonic Mach numbers are used to distinguish this hydrodynamic component of the phase-averaged jet response from the direct actuator noise. As the forcing frequency increases, the compact waves in the near-field pressure signal overlap each other, indicating interaction of the growing seeded structures. For this regime, the phase-averaged response is approximately replicated by linear superposition of the impulse response, thereby demonstrating the quasi-linearity of structure interaction. A novel application of linear parabolized stability theory yields a successful model of the impulse response.
Investigation of photoelectrochemical-oxidized p-GaSb films
Authors: Lee Hsin-Ying , Huang Hung-Lin , Lee Ching-Ting , Petrovich Pchelyakov Oleg , Andreevich Pakhanov Nikolay
Published: December 2012

GaSb oxide films were directly formed on the p-GaSb films using the bias-assisted photoelectrochemical (PEC) oxidation method. X-ray photoelectron spectroscopy analysis indicated that the resulting GaSb oxide films consisted of Ga2O3, Sb2O3, and Sb2O5. Different from the non-PEC oxides, the PEC derived oxide contained much more Sb2O5 than Sb2O3. Besides, the interface state density between the PEC oxide and p-GaSb was lower than that of the ordinary oxide/p-GaSb interface. The high quality of the PEC-oxidized GaSb films was attributed to the increase of the stable Sb2O5 content and decrease of the elemental Sb content in the films.
ErN and HoN spherical regenerator materials for 4 K cryocoolers
Authors: Nakano T. , Masuyama S. , Hirayama Y. , Izawa T. , Nakagawa T. , Fujimoto Y. , Irie T. , Nakamura E. , Yamamoto T. A.
Published: December 2012

HoN and ErN spheres were synthesized by nitriding metallic spheres, and their regenerator performance was investigated by measuring the cooling power, CP, using a commercial Gifford–McMahon cryocooler loaded with the samples. The lowest achieved temperature was below 4.2 K. The CP of the nitride spheres was decreased by the presence of surface roughness, porosity, and oxide impurities. The intrinsic cooling power of ErN, calculated by considering these deficiencies, was greater than that measured for HoCu2. This high performance originates from the large specific heat, which peak at approximately 5 K given by magnetic transition.
Effect of the number of quantum dot layers and dual state emission on the performance of InAs/InGaAs passively mode-locked lasers
Authors: Mesaritakis Charis , Simos Christos , Simos Hercules , Kapsalis Alexandros , Roditi Eugenia , Krestnikov Igor , Syvridis Dimitris
Published: December 2012

In this paper, a series of quantum-dot passively mode-locked Fabry-Perot lasers has been experimentally investigated. The devices vary in terms of number of quantum dot layers, thus allowing the extraction of guidelines regarding the impact of this parameter on the quality of mode locking. Although, theoretical estimations imply that the increase of the quantum dot layers can enhance the emitted optical power but degrade mode-locking stability, the experimental evaluation proved that the existence of dual wavelength emission can affect this trend and allow better performance from devices that do not exhibit excited state emission.
Determination of Schottky barrier profile at Pt/SrTiO3:Nb junction by x-ray photoemission
Authors: Ohashi Naoki , Yoshikawa Hideki , Yamashita Yoshiyuki , Ueda Shigenori , Li Jianyong , Okushi Hideyo , Kobayashi Keisuke , Haneda Hajime
Published: December 2012

The platinum/[niobium-doped strontium titanate] junction (Pt/SrTiO3:Nb) was investigated by x-ray photoemission (XPE) spectroscopy. Aluminum Kα and synchrotron radiation (6 keV) were used to obtain XPE spectra with different probing depths. The broadening and shift of the XPE peaks for SrTiO3:Nb, which resulted from the formation of a potential barrier at the interface, were quantitatively analyzed by fitting simulations. The barrier height was calculated to be 0.7–0.8 regardless of the Nb concentration. Furthermore, the XPE profile of the junction was reproduced when the permittivity of SrTiO3 was assumed to depend on the electric field.
Electron effective mass in n-type electron-induced ferromagnetic semiconductor (In,Fe)As: Evidence of conduction band transport
Authors: Nam Hai Pham , Anh Le Duc , Tanaka Masaaki
Published: December 2012

The electron effective mass (m*) in n-type carrier-induced ferromagnetic semiconductor (In,Fe)As was estimated by using the thermoelectric Seebeck effect. It was found that m* is 0.03 ∼ 0.17m0 depending on the electron concentration, where m0 is the free electron mass. These values are similar to those of electrons in the conduction band of n+ InAs. The Fermi level EF in (In,Fe)As is located at least 0.15 eV above the conduction band bottom. Our results indicate that electron carriers in (In,Fe)As reside in the conduction band, rather than in a hypothetical Fe-related itinerant impurity band.
Artificial neural network based computational model for the prediction of direct solar radiation in Indian zone
Authors: Tomar R. K. , Kaushika N. D. , Kaushik S. C.
Published: December 2012

In this paper, a computational model for the prediction of direct solar radiation based on neural network analysis of atmospheric clearness is developed. It considers that the major portion of direct solar radiation reaching the earth's surface is governed by Sun-Earth geometry and atmospheric transmittance factors which are exactly calculable by clear day model. Additional variations are due to climate and weather phenomena characterized by relative humidity, mean duration of sunshine per hour, and rainfall, etc., in the atmosphere. These variations are taken into account with the help of a composite parameter referred to as atmospheric clearness index (CI) which is determined using artificial neural network analysis. The contour maps of CI as a function of latitude, time of the day, and month of the year are then prepared using the meteorological data of eleven stations. Model simulation and test results of the trained network for two typical locations (not used in training the network) are presented and compared with measured values. The deviations are well within acceptable error limits [percentage root mean square error values for Ahmedabad and Nagpur are 3.34 and 2.06, respectively]. The methodology, for predicting the direct solar radiation at an arbitrary location using the well known parameters such as altitude, latitude, time of the day, day of the year, and CI values derived from the contour maps, is discussed. The outcome of the present ANN model for four arbitrary locations is compared with NASA SSE data sets.
Time evolution of nanosecond runaway discharges in air and helium at atmospheric pressure
Authors: Yatom S. , Vekselman V. , Krasik Ya. E.
Published: December 2012

Time- and space-resolved fast framing photography was employed to study the discharge initiated by runaway electrons in air and He gas at atmospheric pressure. Whereas in the both cases, the discharge occurs in a nanosecond time scale and its front propagates with a similar velocity along the cathode-anode gap, the later stages of the discharge differ significantly. In air, the main discharge channels develop and remain in the locations with the strongest field enhancement. In He gas, the first, diode “gap bridging” stage, is similar to that obtained in air; however, the development of the discharge that follows is dictated by an explosive electron emission from micro-protrusions on the edge of the cathode. These results allow us to draw conclusions regarding the different conductivity of the plasma produced in He and air discharges.
Flexoelectric strain gradient detection using Ba0.64Sr0.36TiO3 for sensing
Authors: Huang Wenbin , Yan Xiang , Kwon Seol Ryung , Zhang Shujun , Yuan Fuh-Gwo , Jiang Xiaoning
Published: December 2012

Strain gradient sensing offers an alternative avenue for in-situ monitoring of onset and growth of cracks in structural health monitoring, where the strain gradient is the most sensitive measurand. In this study, flexoelectric strain gradient sensing structures using Ba0.64Sr0.36TiO3 (BST) were attached on the proximity of an open hole in an aluminum plate, to monitor strain gradient variations of the specimen under a uniaxial dynamic load. Charge outputs of the BST micro-bars showed good linearity with the average strain gradients, with a sensitivity of 88 pC m, which is in good agreement with the theoretical estimation by assuming a 30 μm bonding thickness.
Simulation of electrical characteristics in negative capacitance surrounding-gate ferroelectric field-effect transistors
Authors: Xiao Y. G. , Chen Z. J. , Tang M. H. , Tang Z. H. , Yan S. A. , Li J. C. , Gu X. C. , Zhou Y. C. , Ouyang X. P.
Published: December 2012

The electrical characteristics of surrounding-gate (SG) metal-ferroelectric-semiconductor (MFS) field-effect transistors (FETs) were theoretically investigated by considering the ferroelectric negative capacitance (NC) effect. The derived results demonstrated that the NC-SG-MFS-FET displays superior electrical properties compared with that of the traditional SG-MIS-FET, in terms of better electrostatic control of the gate electrode over the channel, smaller subthreshold swing (S < 60 mV/dec), and bigger value of ION. It is expected that this investigation may provide some insight into the design and performance improvement for the fast switching and low power dissipation applications of ferroelectric FETs.
Comparing the emissive dipole orientation of two similar phosphorescent green emitter molecules in highly efficient organic light-emitting diodes
Authors: Liehm Philipp , Murawski Caroline , Furno Mauro , Lüssem Björn , Leo Karl , Gather Malte C.
Published: December 2012

We investigate the average orientation of the transition dipole moments of two green phosphorescent emitters Ir(ppy)3 and Ir(ppy)2(acac) embedded in a CBP matrix, using in-situ angle resolved electroluminescence spectroscopy and optical simulations. The dipole orientation of Ir(ppy)3 is nearly isotropic while 77% of the dipoles are horizontally aligned for Ir(ppy)2(acac). Optimized organic light-emitting diodes based on these emitters achieve external quantum efficiencies of 18.3% (Ir(ppy)3) and 21.7% (Ir(ppy)2(acac)). This difference is partially explained by the different dipole orientations.
Intrinsic superconductivity in ABA-stacked trilayer graphene
Authors: Liu Haiwen , Jiang Hua , Xie X. C.
Published: December 2012

We study the phonon-mediated superconductivity in light doped ABA-stacked trilayer graphene system by means of two theoretical models. We find superconducting transition temperature TC can be greatly enlarged by tuning the Fermi energy away from neutral point. Utilizing realistic parameters, we find Tc is approximately 1 K even under weak doping condition EF = 0.1 eV. Specifically, we give out the analytical expression for superconductivity gap △ and superconducting transition temperature Tc for negative-U Hubbard model. Further, we consider the thermal fluctuation and calculate the Berezinskii-Kosterlitz-Thouless critical temperature TBKT. Besides, we consider a two-band BCS model in comparision with the negative-U Hubbard model. The results for both models are qualitatively consistent. Our study provides a promising possibility for realizing intrinsic superconductivity in multilayer graphene systems.
First-sharp diffraction peaks in amorphous GeTe and Ge2Sb2Te5 films prepared by vacuum-thermal deposition
Authors: Nakaoka Toshihiro , Satoh Hiroki , Honjo Saori , Takeuchi Hideo
Published: December 2012

We report on a presence of intermediate-range order in amorphous GeTe and Ge2Sb2Te5 phase change films prepared by simple vacuum-thermal deposition. We find that thermally deposited GeTe and Ge2Sb2Te5 films show significant first sharp diffraction peaks (FSDPs) in the X-ray diffraction pattern, although the intensities in GeTe and Ge2Sb2Te5 fabricated by sputtering technique have previously been reported to be very small due to their characteristic structures. This is in contrast to the case of strong network forming glasses like As-S(Se) and Ge-S(Se), in which FSDPs are clearly observed both in evaporated and sputtered films. The observed fabrication-dependent intermediate-range structures in the amorphous Ge-Sb-Te system help in exploring the physics of the metastable forms of amorphous semiconductors and the phase change mechanism.
Anal cytological abnormalities are poor predictors of high-grade intraepithelial neoplasia amongst HIV-positive men who have sex with men
Authors: Botes Leon P. , Pett Sarah , Carr Andrew , Marriott Debbie , Cooper David A. , Matthews Gail , Carbone Sonia , Kumaradevan Nirmala , McHugh Leo , Hillman Richard J.
Published: December 2012

Background
Although anal squamous cell carcinomas (ASCC) are rare in the general community, rates of ASCC among HIV-positive men who have sex with men (MSM) approach those of major cancers in the general community, such as colorectal and lung cancers. Anal cytology and high-resolution anoscopy (HRA) have been proposed as methods for the diagnosis of high-grade anal intraepithelial neoplasia (HGAIN), the precursor of ASCC. To determine the prevalence of anal disease among HIV-positive MSM, we investigated anal cytological and histological findings in men from a large HIV clinic in Sydney, Australia. Methods: This was a single-centre study conducted between October 2008 and January 2010. Participants self-collected cytology specimens, and those yielding abnormal cytology results of atypical cells of undetermined significance, atypical cells of undetermined significance – possibly high-grade (ASC-H) and high-grade squamous intraepithelial lesions (HSIL) were offered HRA. In addition, of those yielding low-grade squamous intraepithelial lesions results, a systematically selected group (25%) were offered HRA. Results: Of the 1339 HIV-positive MSM who attended the clinic during the study period, 291 (31.8%) were finally included in the study, 262 yielded technically satisfactory cytological results and 101 (36.7%) participants underwent HRA. HGAIN was identified in 55 (54.5%) of the 101 men undergoing HRA. HGAIN was diagnosed in 28 (52.7%) without cytological ASC-H or HSIL results. Conclusions: Despite the poor correlation between anal cytological and histological findings, high levels of HGAIN were identified in HIV-positive MSM attending this clinical service.