bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of photomodulated reflectance on staircase-like, n-doped GaAs/Al
x
Ga1−xAs quantum well structures
Authors: Donmez Omer , Nutku Ferhat , Erol Ayse , Arikan Cetin M , Ergun Yuksel 
Published: November 2012

Abstract
In this study, photomodulated reflectance (PR) technique was employed on two different quantum well infrared photodetector (QWIP) structures, which consist of n-doped GaAs quantum wells (QWs) between undoped Al
x
Ga1−x
As barriers with three different x compositions. Therefore, the barrier profile is in the form of a staircase-like barrier. The main difference between the two structures is the doping profile and the doping concentration of the QWs. PR spectra were taken at room temperature using a He-Ne laser as a modulation source and a broadband tungsten halogen lamp as a probe light. The PR spectra were analyzed using Aspnes’ third derivative functional form.
Since the barriers are staircase-like, the structure has different ground state energies; therefore, several optical transitions take place in the spectrum which cannot be resolved in a conventional photoluminescence technique at room temperature. To analyze the experimental results, all energy levels in the conduction and in the valance band were calculated using transfer matrix technique, taking into account the effective mass and the parabolic band approximations. A comparison of the PR results with the calculated optical transition energies showed an excellent agreement. Several optical transition energies of the QWIP structures were resolved from PR measurements. It is concluded that PR spectroscopy is a very useful experimental tool to characterize complicated structures with a high accuracy at room temperature.
Prevalence and Correlates of Mental Distress Among Working Adults in Ethiopia
Authors: Gelaye Bizu , Lemma Seblewengel , Deyassa Negussie , Bahretibeb Yonas , Tesfaye Markos , Berhane Yemane , Williams Michelle A 
Published: November 2012

Objective:To evaluate the prevalence of mental distress and its correlates among working Ethiopian adults.Methods:This cross-sectional study of 2,180 individuals (1,316 men and 864 women) was conducted among working adults in Addis Ababa, Ethiopia. A structured questionnaire was used to collect information on socio-demographic and lifestyle characteristics of participants. Mental distress was assessed using the self-reporting questionnaire (SRQ). Logistic regression was employed to estimate adjusted odds ratios (OR) and 95% confidence intervals (95% CI).Results:The prevalence of mental distress in the study sample was 17.7% (25.9% in women and 12.4% in men). Younger participants (age ≤24 years) had the highest prevalence of mental distress (35.5% in women and 16.7% in men). The odds of mental distress was 2.47-fold higher among women as compared with men (OR=2.47, 95% CI 1.97-3.09). Participants reporting excellent health status had a 50% reduced odds of mental distress (OR=0.47; 95%CI: 0.38-0.59); and moderate alcohol consumption was associated with a slight increased odds of mental distress (OR=1.26; 95%CI: 1.00-1.67).Conclusion:A high prevalence of mental distress was observed among working adults in Ethiopia. Our findings suggest that the workforce institutions should provide targeted prevention and intervention programs to improve the mental health state of their employees. National mental health policy that clearly outlines and addresses mental distress among working adults is also warranted.
Raman studies of Pd-C nanocomposites
Authors: Belka Radoslaw , Suchanska Malgorzata , Czerwosz Elzbieta , Keczkowska Justyna 
Published: November 2012

Abstract
The results of studying palladium-carbon (Pd-C) nanocomposites using Raman spectroscopy are presented. This method has been used for studying samples having various palladium content, prepared by a one-step Physical Vapour Deposition (PVD) process and a Chemical Vapour Deposition (two-step PVD/CVD) process using different process parameters. For samples obtained by PVD, the vibration bands characteristic of C60 fullerene molecules were observed in the spectra, whereas for layers obtained by PVD/CVD, the Raman spectra displayed mainly D and G bands characteristic solely of the prescence of graphite-like layers’ vibrations. The analysis of the obtained Raman spectra reveals that its shape is affected by many parameters including type of substrate, temperature, and the percentage content of Pd in the studied layer. The quantitative analysis of spectra for layers obtained using the PVD/CVD process shows a difference in the relative intensity of bands D and G, reflecting the different degrees of amorphisation in the investigated nanocomposites.
Hydrodynamics in a vessel stirred by simple and double helical ribbon impellers
Authors: Ameur Houari , Bouzit Mohamed , Ghenaim Abdellah 
Published: November 2012

Abstract
The present paper treats the agitation of shear thinning fluids in a cylindrical unbaffled vessel with a flat-bottom. Two kinds of impellers have been used: simple and double helical ribbons. This work is achieved with the help of CFD package (CFX-12.0), which is based on the finite volume method to solve the continuity and momentum equations. The effect of impeller rotational speed, fluid rheology, impeller size, impeller clearance from the tank bottom on the flow fields and power consumption have been investigated. Finally, a comparison between the two impellers is made. It was found that the best performance is obtained with double helical ribbon impeller placed at the middle of the tank, with moderate blade size and operating at Re
g > 20. Our results have been compared with those of other literatures and a satisfactory agreement is observed.
A variational approach to a BVP arising in the modelling of electrically conducting solids
Authors: Khuri Suheil , Wazwaz Abdul-Majid 
Published: November 2012

Abstract
The purpose of this paper is to apply an amended variational scheme, based on an adapted domain decomposition, for the solution of a second-order nonlinear boundary value problem that arises in applications involving the diffusion of heat generated by positive temperature dependent sources. The underlying idea of this approach is to decompose the original interval prior to the implementation of the iterative variational approach in order to improve the accuracy and acquire uniform convergence to the exact solution over the entire domain. Convergence analysis is given and then numerical experiments are carried out to make obvious the convergence, accuracy and efficient applicability of the method.
Predicting the Unpredictable: Forecastable Bubbles and Business Cycles under Rational Expectations
Authors: Gracia Eduard 
Published: November 2012

Abstract
A popular interpretation of the Rational Expectations/Efficient Markets hypothesis states that, if it holds, market valuations must follow a random walk; hence, the hypothesis is frequently criticized on the basis of empirical evidence against such a prediction. Yet this reasoning incurs what we could call the ‘fallacy of probability diffusion symmetry’: although market efficiency does indeed imply that the mean (i.e. ‘expected’) path must rule out any cyclical or otherwise arbitrage-enabling pattern, if the probability diffusion process is asymmetric the observed path will most closely resemble not the mean but the median, which is not subject to this condition. In this context, this paper develops an efficient markets model where the median path of Tobin’s q ratio displays regular, periodic cycles of bubbles and crashes reflecting an agency problem between investors and producers. The model is tested against U.S. market data, and its results suggest that such a regular cycle does indeed exist and is statistically significant. The aggregate production model in Gracia (Uncertainty and Capacity Constraints: Reconsidering the Aggregate Production Function, 2011) is then put forward to show how financial fluctuations can drive the business cycle by periodically impacting aggregate productivity and, as a consequence, GDP growth.
Mentoring Activities of Senior Nurses and Performance of Nurse Trainees
Authors: Olaer Danilo C. 
Published: November 2012

Mentoring is an important aspect in any field of discipline. It fosters an environment for the novice to imbibe the real work setting. This study ascertained the mentoring activities of senior nurses and the performance of nurse trainees. It utilized descriptive–correlational research design using a researcher-made questionnaire. The study was conducted at St. Vincent General Hospital, Cebu City, Philippines. The research subjects were the senior nurses while the respondents were the nurse trainees who underwent a training program. The data were statistically treated using simple percentage, weighted mean and Pearson-r. Based on the findings of the study, the mentoring activities exhibited by the senior nurses include those that reflect their roles as standard prodder model and envisioned. The respondents’ performance was found to be satisfactory based on the records of Human Resource Department. There was a significant relationship between mentoring activities and performance. The researcher concluded that performance of nurse trainees was dependent on the mentoring activities of the senior nurses. Thus, the researcher recommended implementing a mentorship training course for the senior nurses and monitoring the performance of nurse trainees by requiring very satisfactory rating as the basis for hiring to deliver maximum level of quality patient care. Keywords - Mentoring, Mentoring Activities, Mentorship, Senior Nurses, Performance, Nurse Trainees, Mentor-Mentee Relationship
Relationship between chemokine receptor expression, chemokine levels and HIV‐1 replication in the lungs of persons exposed to Mycobacterium tuberculosis
Authors: Kalsdorf Barbara , Skolimowska Keira H. , Scriba Thomas J. , Dawson Rod , Dheda Keertan , Wood Kathryn , Hofmeister Jessica , Hanekom Willem A. , Lange Christoph , Wilkinson Robert J. 
Published: November 2012

Increased susceptibility to tuberculosis following HIV‐1 seroconversion contributes significantly to the tuberculosis epidemic in sub‐Saharan Africa. Lung‐specific mechanisms underlying the interaction between HIV‐1 and Mycobacterium tuberculosis infection are incompletely understood. Here we address these questions by examining the effect of HIV‐1 and latent M. tuberculosis co‐infection on the expression of viral‐entry receptors and ligands in bronchoalveolar lavage (BAL) of HIV‐1‐infected and ‐uninfected patients with and without latent M. tuberculosis infection.Irrespective of HIV‐1 status, T cells from BAL expressed higher levels of the beta‐chemokine receptor (CCR)5 than peripheral blood T cells, in particular the CD8+ T cells of HIV‐1‐infected persons showed elevated CCR5 expression. The concentrations of the CCR5 ligands RANTES and MIP‐1β were elevated in the BAL of HIV‐1‐infected persons compared with that in HIV‐1‐uninfected controls. CCR5 expression and RANTES concentration correlated strongly with HIV‐1 viral load in the BAL. In contrast, these alterations were not associated with M. tuberculosis sensitisation in vivo, nor did M. tuberculosis infection of BAL cells ex vivo change RANTES expression.These data suggest ongoing HIV‐1 replication predominantly drives local pulmonary CCR5+ T‐cell activation in HIV/latent M. tuberculosis co‐infection.
Chalcogenidotellurates(IV) (TeS3)2– and (TeSe3)2– by Low‐Temperature Solvothermal Synthesis from Liquid Ammonia and Methylamine
Authors: Kysliak Oleksandr , Beck Johannes 
Published: November 2012

AbstractThe novel chalcogenidotellurates(IV) [Zn(NH3)6][Zn(NH3)4]2(TeS3)3 (1), [Zn(NH3)4](TeSe3) (2), [Mn(NH3)6](TeS3) (3), [Mn(NH3)6](TeSe3) (4) and [Mn(CH3NH2)6](TeSe3) (5) were obtained by solvothermal reactions from elemental zinc or manganese, tellurium and sulfur or selenium, respectively, in liquid ammonia or methylamine. The reactions were performed in thick‐walled glass ampoules at 50 °C and give 1, 2 and 3 in quantitative yield. The yields for 4 and 5 are lower. The crystal structures consist of tetrammine, hexammine and hexakis(methylamine) complexes of divalent Zn and Mn and of trigonal‐pyramidal (TeCh3)2– (Ch = S, Se) anions. Compounds 1 (P31m) and 2 [two polymorphic forms, Cmc21 (2a) and Pca21 (2b)] crystallise in a noncentrosymmetric manner in polar structures, while 3 (P21/c), 4 (Pbca) and 5 (P21/m) are centrosymmetric. As an unique feature, the structure of 1 contains two different types of Zn ammine complexes, tetrahedral [Zn(NH3)4]2+ and octahedral [Zn(NH3)6]2+. Compound 5 contains the rare hexacoordinate complex [Mn(CH3NH2)6]2+. Raman spectra of 1 and 2 show the two expected symmetric and asymmetric valence vibrations between 350–380 cm–1 for (TeS3)2– and 215–235 cm–1 for (TeSe3)2–.
Tribological properties of alkyl and hydroxyl groups on the imidazolium tetrafluoroborate ionic liquids
Authors: Song Yanxin , Xia Yanqiu , Liu Haiyan , Jia Zhengfeng 
Published: November 2012

ABSTRACTWe present an investigation of effect of alkyl chain length and hydroxyl group functionalisation on the tribological properties of imidazolium tetrafluoroborate ionic liquids. Four kinds of hydroxyl‐functionalised ionic liquids with the alkyl chain of C1–C10 were synthesised, and the relationships between their structure and physicochemical properties such as viscosity, thermal stability and corrosion, before and after incorporation of a hydroxyl group, were measured. In particular, the studies on their lubrication properties as ionic liquid (IL) lubricants for steel–steel contacts, including the friction coefficient, the wear volume and so on, were particularly emphasised. Moreover, an in‐depth exploration about the function mechanism and failure mode of the ILs during the friction process were studied using the scanning electron microscope and X‐ray photoelectron spectroscope technologies, and a proposed interaction model between ILs and steel substrate was presented. Copyright © 2012 John Wiley & Sons, Ltd.
Dynamics of the Foehn Mechanism in the McMurdo Dry Valleys of Antarctica from Polar WRF
Authors: Steinhoff Daniel F. , Bromwich David H. , Monaghan Andrew 
Published: November 2012

AbstractFoehn events over the McMurdo Dry Valleys (MDVs), the largest ice‐free region of Antarctica, promote glacial melt that supports biological activity in the lakes, streams, rocks and soils. Although MDVs foehn events are known to depend upon the synoptic‐scale circulation, the physical processes responsible for foehn events are unknown. A polar‐optimized version of the Weather Research and Forecasting model (Polar WRF) is used for a case study of a representative summer foehn event from 29 December 2006 to 1 January 2007 in order to identify and explain the MDVs foehn mechanism. Pressure differences across an elevated mountain gap upstream of the MDVs provide forcing for southerly flow into the western, upvalley entrance of the MDVs. Complex terrain over the elevated gap and the MDVs leads to mountain wave effects such as leeside acceleration, hydraulic jumps, wave breaking and critical layers. These mountain wave effects depend on the ambient (geostrophic) wind direction. Pressure‐driven channelling then brings the warm, dry foehn air downvalley to eastern MDV sites. Brief easterly intrusions of maritime air into the eastern MDVs during foehn events previously have been attributed to either a sea‐breeze effect in summer or local cold‐pooling effects in winter. In this particular case, the easterly intrusions result from blocking effects of nearby Ross Island and the adjacent Antarctic coast. Temperature variability during the summer foehn event, which is important for meltwater production and biological activity when it exceeds 0°C, primarily depends on the source airmass rather than differences in foehn dynamics.
Mischaracterising density dependence biases estimated effects of coloured covariates on population dynamics
Authors: Lindén Andreas , Fowler Mike S. , Jonzén Niclas 
Published: November 2012

AbstractEnvironmental effects on population growth are often quantified by coupling environmental covariates with population time series, using statistical models that make particular assumptions about the shape of density dependence. We hypothesized that faulty assumptions about the shape of density dependence can bias estimated effect sizes of temporally autocorrelated covariates. We investigated the presence of bias using Monte Carlo simulations based on three common per capita growth functions with distinct density dependent forms (θ‐Ricker, Ricker and Gompertz), autocorrelated (coloured) ‘known’ environmental covariates and uncorrelated (white) ‘unknown’ noise. Faulty assumptions about the shape of density dependence, combined with overcompensatory intrinsic population dynamics, can lead to strongly biased estimated effects of coloured covariates, associated with lower confidence interval coverage. Effects of negatively autocorrelated (blue) environmental covariates are overestimated, while those of positively autocorrelated (red) covariates can be underestimated, generally to a lesser extent. Prewhitening the focal environmental covariate effectively reduces the bias, at the expense of the estimate precision. Fitting models with flexible shapes of density dependence can also reduce bias, but increases model complexity and potentially introduces other problems of parameter identifiability. Model selection is a good option if an appropriate model is included in the set of candidate models. Under the specific and identifiable circumstances with high risk of bias, we recommend prewhitening or careful modelling of the shape of density dependence.
Improved growth media and culture techniques for genetic analysis and assessment of biomass utilization by Caldicellulosiruptor bescii
Authors: Farkas Joel , Chung Daehwan , Cha Minseok , Copeland Jennifer , Grayeski Philip , Westpheling Janet 
Published: November 2012

Abstract
Methods for efficient growth and manipulation of relatively uncharacterized bacteria facilitate their study and are essential for genetic manipulation. We report new growth media and culture techniques for Caldicellulosiruptor bescii, the most thermophilic cellulolytic bacterium known. A low osmolarity defined growth medium (LOD) was developed that avoids problems associated with precipitates that form in previously reported media allowing the monitoring of culture density by optical density at 680 nm (OD680) and more efficient DNA transformation by electroporation. This is a defined minimal medium and does not support growth when a carbon source is omitted, making it suitable for selection of nutritional markers as well as the study of biomass utilization by C. bescii. A low osmolarity complex growth medium (LOC) was developed that dramatically improves growth and culture viability during storage, making it a better medium for routine growth and passaging of C. bescii. Both media contain significantly lower solute concentration than previously published media, allowing for flexibility in developing more specialized media types while avoiding the issues of growth inhibition and cell lysis due to osmotic stress. Plating on LOD medium solidified by agar results in ~1,000-fold greater plating efficiency than previously reported and allows the isolation of discrete colonies. These new media represent a significant advance for both genetic manipulation and the study of biomass utilization in C. bescii, and may be applied broadly across the Caldicellulosiruptor genus.
Effect of superthermal electrons on dust-acoustic shock waves in coupled dusty plasmas
Authors: PAKZAD HAMID REZA , TRIBECHE MOULOUD 
Published: November 2012

AbstractNonlinear dust-acoustic (DA) shock waves in coupled dusty plasmas with negative dust grains and kappa-distributed electrons are discussed. Using a generalized hydrodynamic model, the dispersion relation and the Korteweg–de Vries-Burger (KdVB) equation for low-frequency DA modes in a strongly coupled dusty plasma are derived. The dependence of shock waves on various plasma parameters is then explored. A solitonic profile may be converted into a shock structure when correlation among dust particles becomes stronger. The amplitude as well as the steepness of shock waves increases with increasing the value of the spectral index k.
The Bohm-sheath criterion in plasmas containing electrons and multiply charged ions
Authors: KHORAMABADI MANSOUR , GHOMI HAMID , SHUKLA P. K. 
Published: November 2012

AbstractUsing the multi-fluid model of plasmas, we have analytically obtained a generalized Bohm criterion in the plasma, including hot electrons and multiply charged ions, and have numerically examined its validity. The new Bohm-sheath criterion shows that increasing the charge number of positive ions and decreasing the charge number of negative ions would increase the minimum ion speed that is required for the Bohm criterion to satisfy.
The Moghia Menace, or the Watch Over Watchmen In British India
Authors: PILIAVSKY ANASTASIA 
Published: November 2012

AbstractThis paper contributes to the history of ‘criminal tribes’, policing and governance in British India. It focuses on one colonial experiment—the policing of Moghias, declared by British authorities to be ‘robbers by hereditary profession’—which was the immediate precursor of the first Criminal Tribes Act of 1871, but which so far altogether has passed under historians’ radar. I argue that at stake in the Moghia operations, as in most other colonial ‘criminal tribe’ initiatives, was neither the control of crime (as colonial officials claimed) nor the management of India's itinerant groups (as most historians argue), but the uprooting of the indigenous policing system. British presence on the subcontinent was punctuated with periodic panics over ‘extraordinary crime’, through which colonial authorities advanced their policing practices and propagated their way of governance. The leading crusader against this ‘crisis’ was the Thuggee and Dacoity Department, which was as instrumental in the ‘discovery’ of the ‘Moghia menace’ and ‘criminal tribes’ in the late nineteenth century as in the earlier suppression of the ‘cult of Thuggee’. As a policing initiative, the Moghia campaign failed consistently for more than two decades. Its failures, however, reveal that behind the façade-anxieties over ‘criminal castes’ and ‘crises of crime’ stood attempts at a systemic change of indigenous governance. The diplomatic slippages of the campaign also expose the fact that the indigenous rule by patronage persisted—and that the consolidation of the colonial state was far from complete—well into the late nineteenth century.
Geographical distribution and epidemiological features of Old WorldLeishmania infantumandLeishmania donovanifoci, based on the isoenzyme analysis of 2277 strains
Authors: PRATLONG FRANCINE , LAMI PATRICK , RAVEL CHRISTOPHE , BALARD YVES , DEREURE JACQUES , SERRES GHISLAINE , BAIDOURI FOUAD EL , DEDET JEAN-PIERRE 
Published: November 2012

SUMMARYA series of 2277Leishmaniastrains from Old World visceral leishmaniasis foci, isolated between 1973 and 2008, were studied by isoenzyme analysis. The strains were obtained from humans, domestic and wild carnivores, rodents and phlebotomine sandflies, and came from 36 countries. In all, 60 different zymodemes were identified and clustered by a phenetic analysis into 3 different groups corresponding to the typically visceralizing speciesL. donovani(20 zymodemes, 169 strains),L. archibaldi(3 zymodemes, 46 strains) andL. infantum(37 zymodemes, 2,062 strains). The taxonomic position of these isoenzymatic groups is discussed in view of contradictory results obtained from recent molecular studies.