bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of initial turbulence level on the flow and sound fields of a subsonic jet at a diameter-based Reynolds number of 105
Authors: Bogey C. , Marsden O. , Bailly C. 
Published: May 2012

AbstractFive isothermal round jets at Mach number $M= 0. 9$ and Reynolds number ${\mathit{Re}}_{D} = 1{0}^{5} $ originating from a pipe nozzle are computed by large-eddy simulations to investigate the effects of initial turbulence on flow development and noise generation. In the pipe, the boundary layers are untripped in the first case and tripped numerically in the four others in order to obtain, at the exit, mean velocity profiles similar to a Blasius laminar profile of momentum thickness equal to 1.8 % of the jet radius, yielding Reynolds number ${\mathit{Re}}_{\theta } = 900$, and peak turbulence levels ${ u}_{e}^{\ensuremath{\prime} } $ around 0, 3 %, 6 %, 9 % or 12 % of the jet velocity ${u}_{j} $. As the initial turbulence intensity increases, the shear layers develop more slowly with much lower root-mean-square (r.m.s.) fluctuating velocities, and the jet potential cores are longer. Velocity disturbances downstream of the nozzle exit also exhibit different structural characteristics. For low ${ u}_{e}^{\ensuremath{\prime} } / {u}_{j} $, they are dominated by the first azimuthal modes ${n}_{\theta } = 0$, 1 and 2, and show significant skewness and intermittency. The growth of linear instability waves and a first stage of vortex pairings occur in the shear layers for ${ u}_{e}^{\ensuremath{\prime} } / {u}_{j} \leq 6\hspace{0.167em} \% $. For higher ${ u}_{e}^{\ensuremath{\prime} } / {u}_{j} $, three-dimensional features and high azimuthal modes prevail, in particular close to the nozzle exit where the wavenumbers naturally found in turbulent wall-bounded flows clearly appear. Concerning the sound fields, strong broadband components mainly associated with mode ${n}_{\theta } = 1$ are noticed around the pairing frequency for the untripped jet. With rising ${ u}_{e}^{\ensuremath{\prime} } / {u}_{j} $, however, they become weaker, and the noise levels decrease asymptotically down to those measured for jets at ${\mathit{Re}}_{D} \geq 5\ensuremath{\times} 1{0}^{5} $, which are likely to be initially turbulent and to emit negligible vortex-pairing noise. These results correspond well to experimental observations, made separately for either mixing layers, jet flow or sound fields.
Non-axisymmetric Homann stagnation-point flows
Authors: Weidman P. D. 
Published: May 2012

AbstractA modification of Homann’s axisymmetric outer potential stagnation-point flow of strain rate $a$ is obtained by adding periodic radial and azimuthal velocities of the form $b\hspace{0.167em} r\sin 2\theta $ and $b\hspace{0.167em} r\cos 2\theta $, respectively, where $b$ is a shear rate. This leads to the discovery of a new family of asymmetric viscous stagnation-point flows depending on the shear-to-strain-rate ratio $\gamma = b/ a$ that exist over the range $\ensuremath{-} \infty \lt \gamma \lt \infty $. Numerical solutions for the wall shear stress parameters and the displacement thicknesses are given and compared with their large-$\gamma $ asymptotic behaviours. Sample similarity velocity profiles are also presented.
ON WEAKLY s-PERMUTABLY EMBEDDED SUBGROUPS OF FINITE GROUPS II
Authors: QIAO SHOUHONG , WANG YANMING 
Published: May 2012

AbstractA subgroup H is called weakly s-permutably embedded in G if there are a subnormal subgroup T of G and an s-permutably embedded subgroup Hse of G contained in H such that G=HT and H∩T≤Hse. In this note, we study the influence of the weakly s-permutably embedded property of subgroups on the structure of G, and obtain the following theorem. Let ℱ be a saturated formation containing 𝒰, the class of all supersolvable groups, and G a group with E as a normal subgroup of G such that G/E∈ℱ. Suppose that P has a subgroup D such that 1<∣D∣<∣P∣ and all subgroups H of P with order ∣H∣=∣D∣ are s-permutably embedded in G. Also, when p=2 and ∣D∣=2 , we suppose that each cyclic subgroup of P of order four is weakly s-permutably embedded in G. Then G∈ℱ.
Cooperating internationally over water: explaining l'espace OMVS
Authors: Alam Undala 
Published: May 2012

ABSTRACTSince the early 1960s, Guinea, Mali, Mauritania and Senegal have cooperated over the Senegal river. Contrary to the norms of managing international rivers, the riparians have subjugated their sovereignty and incurred national debt to jointly develop the benefits from their shared river, despite intra-basin tensions and conflict. The Senegal experience highlights an alternative path to tackling the consequences of climate change, poor water management and increasing demand. In seeking to explain the intensity of international cooperation displayed in the basin, this article examines the characteristics of international rivers and the Senegal basin's history, and concludes that Pan-Africanism, francophonie and the political leaders' attitudes to regional cooperation shaped l'espace OMVS.
Negotiating social change: Ugandan discourses on Westernisation and neo-colonialism as forms of social critique
Authors: Vorhölter Julia 
Published: May 2012

ABSTRACTA common claim, in public discourses and in post-colonial theory, is that colonialism, and more recently the aid industry and the media, have created global hegemonic norms, which have been enforced on non-Western societies. While this may be true in some respects, this article takes a different stance on the debate. It scrutinises perceptions of Western-influenced social change in Uganda, and differentiates between discourses on Westernisation and discourses on neo-colonialism. Both are analysed as forms of social critique – one internally and the other externally oriented. The largely elitist discourse on neo-colonialism is explicitly critical of the West and its interventions in Uganda. But it is not representative of the more ambiguous perceptions of Westernisation among ‘ordinary’ people, who use references to the West to comment on contemporary Ugandan society. The article is based on empirical research in Northern Uganda. It focuses on discourses on gender, kinship and sexuality, and the recent debate on homosexuality.
TESTING UNDER WEAK IDENTIFICATION WITH CONDITIONAL MOMENT RESTRICTIONS
Authors: Jun Sung Jae , Pinkse Joris 
Published: May 2012

AbstractWe propose a semiparametric test for the value of coefficients in models with conditional moment restrictions that has correct size regardless of identification strength. The test is in essence an Anderson-Rubin (AR) test using nonparametrically estimated instruments to which we apply a standard error correction. We show that the test is (1) always size-correct, (2) consistent when identification is not too weak, and (3) asymptotically equivalent to an infeasible AR test when identification is sufficiently strong. We moreover prove that under homoskedasticity and strong identification our test has a limiting noncentral chi-square distribution under a sequence of local alternatives, where the noncentrality parameter is given by a quadratic form of the inverse of the semiparametric efficiency bound.
Impact of land-use changes on red-legged partridge conservation in the Iberian Peninsula
Authors: DELIBES-MATEOS MIGUEL , FARFÁN MIGUEL ÁNGEL , OLIVERO JESÚS , VARGAS JUAN MARIO 
Published: May 2012

SUMMARYRed-legged partridge (Alectoris rufa) populations have significantly declined in the Iberian Peninsula (by > 50% between 1973 and 2002). This decline has been attributed to the drastic changes that have occurred in traditional agricultural landscapes, among other factors. This paper assesses the relationship between landscape change and the changes in areas favourable to partridges. The areas favourable to partridges in Andalusia (southern Spain), and the environmental and land-use factors that determined these areas, were identified for both the 1960s and the 1990s. Land-use changes were analysed both throughout the study area and for areas where favourability for partridges has either improved or worsened during recent decades. Both the location and the factors determining areas favourable to red-legged partridges have changed substantially over recent decades. In the 1960s, areas favourable to partridges were associated mainly with natural vegetation in mountainous areas, whereas, by the 1990s, favourable areas were associated with large low-lying croplands; such change may be attributable to regional land-use changes. The percentage area of the main natural vegetation variables positively correlated to partridge favourability in the 1960s model (mainly pastures and open scrubland) had decreased in areas that had become unfavourable to the species (such as mountain areas), and risen where partridge favourability increased. By the 1990s, the land area favourable to partridges had decreased byc. 10% (c. 6000 km2) in southern Spain, whereas land use unfavourable to partridges markedly increased (> 100%; an increase ofc. 3000 km2). Landscape suitable for partridges has thus become severely impoverished over recent decades in the Iberian Peninsula. Management measures aimed at improving the landscape for farmland birds should be encouraged to conserve red-legged partridge populations in southern Spain.
Perceived Discrimination and Cognition in Older African Americans
Authors: Barnes L.L. , Lewis T.T. , Begeny C.T. , Yu L. , Bennett D.A. , Wilson R.S. 
Published: May 2012

AbstractExisting evidence suggests that psychosocial stress is associated with cognitive impairment in older adults. Perceived discrimination is a persistent stressor in African Americans that has been associated with several adverse mental and physical health outcomes. To our knowledge, the association of discrimination with cognition in older African Americans has not been examined. In a cohort of 407 older African Americans without dementia (mean age = 72.9;SD= 6.4), we found that a higher level of perceived discrimination was related to poorer cognitive test performance, particularly episodic memory (estimate = −0.03;SE= .013;p< .05) and perceptual speed tests (estimate = −0.04;SE= .015;p< .05). The associations were unchanged after adjusting for demographics and vascular risk factors, but were attenuated after adjustment for depressive symptoms (Episodic memory estimate = −0.02;SE= 0.01; Perceptual speed estimate = −0.03;SE= 0.02; bothp's = .06). The association between discrimination and several cognitive domains was modified by level of neuroticism. The results suggest that perceived discrimination may be associated with poorer cognitive function, but does not appear to be independent of depressive symptoms. (JINS, 2012,18, 1–10)
Dopamine D4 receptor gene variation is associated with context-dependent attention for emotion stimuli
Authors: Wells Tony T. , Beevers Christopher G. , Knopik Valerie S. , McGeary John E. 
Published: May 2012

AbstractDopamine D4 receptor (DRD4) gene variation has been associated with biased attention for contextually relevant information (e.g. images of cigarettes among smokers). No research has examined whether DRD4 variation is associated with biased attention for contextually cued emotion stimuli, an important putative intermediate phenotype for a number of pathologies (e.g. depression and anxiety). We conducted two studies examining the relationship between the DRD4 variable number tandem repeats polymorphism and attention bias for facial expressions of emotion following a mood-state manipulation in healthy young adult samples. Study 1 demonstrated that long (i.e. seven or greater tandem repeats) DRD4 allele carriers vs. short DRD4 homozygotes had increased attention for sad facial stimuli, but only after a sad mood provocation. Study 2 demonstrated an association between the long DRD4 allele and attention for negative stimuli (sad and fear expressions) following a sad mood provocation. These studies are the first to demonstrate an association between the long DRD4 allele and biased attention for contextually cued emotion stimuli, an important cognitive mechanism thought to increase risk for affective psychopathology. Implications of these studies for vulnerability and plasticity models of psychiatric genetics are discussed.
Principal component analysis of polar cap convection
Authors: Kim H.‐J. , Lyons L. R. , Ruohoniemi J. M. , Frissell N. A. , Baker J. B. 
Published: May 2012

We apply a statistical technique called Principal Component Analysis (PCA) for examining underlying patterns of polar cap convection and illustrate potential applications of the PCA‐based dimension reduction. Two principal components are identified: the first mode (PC1) is related to “uniform variation” of the flow speed at all MLTs, and is primarily governed by IMF Bz. The second mode (PC2) is related to “dawn‐dusk asymmetry”, and is predominantly driven by IMF By. PCA gives the relative variance contribution of the two modes: PC1 giving ∼42% of the total variance and PC2 ∼17% of the total variance, which is about 40% of that from PC1. Due to the orthogonality of the principal components, the degree of dawn‐dusk asymmetry can be represented byP2, where P2 is a component value when the observed data are projected along PC2. We identified P2 as proportional to IMF By, which leads to stronger dawn flows for By > 0 and stronger dusk flows for By < 0. The same primary modes are found regardless of the IMF orientation, implying that they are intrinsic properties of the average polar cap convection.
The influence of different indium-composition profiles on the electronic structure of lens-shaped InxGa1−xAs quantum dots
Authors: Maia A D B , da Silva E C F , Quivy A A , Bindilatti V , de Aquino V M , Dias I F L 
Published: May 2012

Abstract
We present effective-mass calculations of the bound-state energy levels of electrons confined inside lens-shaped In
x
Ga1−x
As quantum dots (QDs) embedded in a GaAs matrix, taking into account the strain as well as the In gradient inside the QDs due to the strong In segregation and In-Ga intermixing present in the In
x
Ga1−x
As/GaAs system. In order to perform the calculations, we used a continuum model for the strain, and the QDs and wetting layer were divided into their constituting monolayers, each one with a different In concentration, to be able to produce a specific composition profile. Our results clearly show that the introduction of such effects is very important if one desires to correctly reproduce or predict the optoelectronic properties of these nanostructures.
Structured-gate organic field-effect transistors
Authors: Aljada Muhsen , Pandey Ajay K , Velusamy Marappan , Burn Paul L , Meredith Paul , Namdas Ebinazar B 
Published: May 2012

Abstract
We report the fabrication and electrical characteristics of structured-gate organic field-effect transistors consisting of a gate electrode patterned with three-dimensional pillars. The pillar gate electrode was over-coated with a gate dielectric (SiO2) and solution processed organic semiconductors producing both unipolar p-type and bipolar behaviour. We show that this new structured-gate architecture delivers higher source–drain currents, higher gate capacitance per unit equivalent linear channel area, and enhanced charge injection (electrons and/or holes) versus the conventional planar structure in all modes of operation. For the bipolar field-effect transistor (FET) the maximum source–drain current enhancements in p- and n-channel mode were >600% and 28%, respectively, leading to p and n charge mobilities with the same order of magnitude. Thus, we have demonstrated that it is possible to use the FET architecture to manipulate and match carrier mobilities of material combinations where one charge carrier is normally dominant. Mobility matching is advantageous for creating organic logic circuit elements such as inverters and amplifiers. Hence, the method represents a facile and generic strategy for improving the performance of standard organic semiconductors as well as new materials and blends.
Measurement of OH density and air–helium mixture ratio in an atmospheric-pressure helium plasma jet
Authors: Yonemori Seiya , Nakagawa Yusuke , Ono Ryo , Oda Tetsuji 
Published: May 2012

Abstract
The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air–helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals.
Structural evolution and chemical bonds in electrochromic WO3 films during electrochemical cycles
Authors: Wang Chun-Kai , Sahu D R , Wang Sheng-Chang , Lin Chung-Kwei , Huang Jow-Lay 
Published: May 2012

Abstract
Electrochromic WO3 films are prepared by the electron-beam evaporation method. The as-deposited films are amorphous in structure. The optical transmittance spectra show 13.4% decay of optical modulation after 20 electrochemical cycles. The degradation behaviour of the WO3 films is also observed in electrochemical step potential measurements. X-ray absorption spectroscopy indicates that the absorption energy of the W LIII-edge shifts towards lower energy with the insertion of Li+ ions and electrons. The results of radial distribution functions reveal that the increase in the distance of the W–O bonds is caused by the reduction in W ions. Li
x
WO3 and Li2WO4 are formed at −0.5 V and −1.0 V, respectively, during electrochemical insertion, as observed by transmission electron microscopy. The Raman scattering analysis indicates that only two ionic states, W4+ and W6+, exist in the WO3 films, due to excess injection of electrons and Li+ ions. We suggest that the degradation of the electrochromic properties of the WO3 films during electrochemical cycles is related to the formation of different W ionic states.
Robust identification of transcriptional regulatory networks using a Gibbs sampler on outlier sum statistic
Authors: Gu Jinghua , Xuan Jianhua , Riggins Rebecca B. , Chen Li , Wang Yue , Clarke Robert 
Published: May 2012

Abstract
Motivation: Identification of transcriptional regulatory networks (TRNs) is of significant importance in computational biology for cancer research, providing a critical building block to unravel disease pathways. However, existing methods for TRN identification suffer from the inclusion of excessive ‘noise’ in microarray data and false-positives in binding data, especially when applied to human tumor-derived cell line studies. More robust methods that can counteract the imperfection of data sources are therefore needed for reliable identification of TRNs in this context.
Results: In this article, we propose to establish a link between the quality of one target gene to represent its regulator and the uncertainty of its expression to represent other target genes. Specifically, an outlier sum statistic was used to measure the aggregated evidence for regulation events between target genes and their corresponding transcription factors. A Gibbs sampling method was then developed to estimate the marginal distribution of the outlier sum statistic, hence, to uncover underlying regulatory relationships. To evaluate the effectiveness of our proposed method, we compared its performance with that of an existing sampling-based method using both simulation data and yeast cell cycle data. The experimental results show that our method consistently outperforms the competing method in different settings of signal-to-noise ratio and network topology, indicating its robustness for biological applications. Finally, we applied our method to breast cancer cell line data and demonstrated its ability to extract biologically meaningful regulatory modules related to estrogen signaling and action in breast cancer.
Availability and implementation: The Gibbs sampler MATLAB package is freely available at http://www.cbil.ece.vt.edu/software.htm.
Contact: xuan@vt.edu
Supplementary information: Supplementary data are available at Bioinformatics online.
Burden of Illness in Screen‐detected Children With Celiac Disease and Their Families
Authors: Kinos Sampsa , Kurppa Kalle , Ukkola Anniina , Collin Pekka , Lähdeaho Marja‐Leena , Huhtala Heini , Kekkonen Leila , Mäki Markku , Kaukinen Katri 
Published: May 2012

ABSTRACTObjectives:Because of a variable clinical picture, most children with celiac disease remain unrecognized without active serologic screening. Because, however, many patients are asymptomatic, the justification for screening remains unclear. We assessed health and well‐being and the effect of a 1‐year gluten‐free diet in a nationwide cohort of children with celiac disease detected by screening in at‐risk groups.Methods:A total of 222 newly detected children received a validated questionnaire covering aspects of the burden caused by the undiagnosed celiac disease. After 1 year, adherence to the diet and difficulties attending this, attitudes toward and effects of disease and diet on daily life, and parents' satisfaction with the diagnosis were inquired about. The children's health and parents' concern for it were asked about at diagnosis and on treatment. The outcomes of screen‐detected children were compared with those of children diagnosed on the basis of clinical symptoms.Results:Forty‐three screen‐detected and 88 symptom‐detected children responded. Also, 65% of the screen‐detected patients experienced symptoms; these, however, being less troublesome and of shorter duration than in symptom‐detected subjects. There were no differences between the groups in dietary adherence (71% vs 84% strict diet), management of the diet (80% vs 80%), alleviation of symptoms (78% vs 86%), and improvement in daily life (73% vs 69%), or in satisfaction with the diagnosis (93% vs 88%). Improved health and reduced parental concern were observed in both groups.Conclusions:Screen‐detected children with celiac disease can attain satisfactory dietary adherence and benefit from treatment similarly to symptom‐detected patients. The results support intensified screening for celiac disease in at‐risk children.