bluuebunny/crossref_metadata_2025 huggingface dataset:
ON WEAKLY s-PERMUTABLY EMBEDDED SUBGROUPS OF FINITE GROUPS II
Authors: QIAO SHOUHONG , WANG YANMING
Published: May 2012

A 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

Since 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

A 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.
Towards amino acid recommendations for specific physiological and patho-physiological states in pigs
Authors: Le Floc'h Nathalie , Gondret Florence , Matte J. Jacques , Quesnel Hélène
Published: May 2012

The objective of this review is to provide an overview of the implication of amino acids (AA) in important physiological functions. This is done in the context of pig production where the competition for AA utilisation is exacerbated by constraints to maximise productive responses and the necessity to reduce dietary protein input for environmental, economic and sanitary issues. Therefore, there is an opportunity to refine the nutritional recommendations by exploring the physiological roles of AA. For example, methionine and cysteine, either in selenised or sulfur forms, are directly involved in the regulation of the glutathione antioxidative system. In sows, glutathione antioxidative system may contribute to improving ovulation conditions through control of oxidative pressure. Supplementation of sow diets withl-arginine, a precursor of NO and polyamines, may stimulate placental growth, promoting conceptus survival, growth and tissue development. The beneficial effect of arginine supplementation has been also suggested to improve lactation performance. Feed intake is usually the first response that is impacted by an inadequate AA supply. Valine and tryptophan imbalances may act as signals for decreasing feed intake. AA are also important nutrients for maintaining the animal's defence systems. Threonine, one of the main constituents of mucin protein, is important for gut development during the postnatal period. It may exert a protective effect that reduces the impact of weaning on gut morphology and associated disturbances. Finally, tryptophan is involved in the regulation of the defence system through its action as a precursor of antioxidants and its effect on the inflammatory response.
TESTING UNDER WEAK IDENTIFICATION WITH CONDITIONAL MOMENT RESTRICTIONS
Authors: Jun Sung Jae , Pinkse Joris
Published: May 2012

We 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

Red-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.
Bookreview JFP: Domain-Specific Languages by Martin Fowler The Addison Wesley Signature Series
Authors: HAGE JURRIAAN
Published: May 2012

My main reason for wanting to read this book was to find out what a well-known publicist from the world of OO would have to say about the state of the art of domain specific languages (DSLs), in particular when it comes to type error feedback, functional programming, and the combination. As most readers will be aware, languages like Scheme and Haskell are very well suited to embed DSLs in: Scheme can be considered a core language to which new language facilities can be easily added by means of hygienic syntax macro's (Abelsonet al. 1998), and there are so many papers on embedded DSLs in Haskell (Hudak, 1998), that any realistic selection would aggravate more people than I would please. Great was my disappointment when I read on page XXV that these topics were not discussed at all in the book. Although I can imagine that Fowler does not feel comfortable writing about subjects he is not sufficiently at home with, the question does arise whether the title of this book is sufficiently covered by its contents.
A quantum double construction in Rel
Authors: HASEGAWA MASAHITO
Published: May 2012

We study bialgebras and Hopf algebras in the compact closed categoryRelof sets and binary relations. Various monoidal categories with extra structure arise as the categories of (co)modules of bialgebras and Hopf algebras inRel. In particular, for any groupG, we derive a ribbon category of crossedG-sets as the category of modules of a Hopf algebra inRelthat is obtained by the quantum double construction. This category of crossedG-sets serves as a model of the braided variant of propositional linear logic.
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

Existing 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

Dopamine 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.
Maternal protein restriction before pregnancy reduces offspring early body mass and affects glucose metabolism in C57BL/6JBom mice
Authors: Dudele A. , Lund S. , Jessen N. , Wegener G. , Winther G. , Elnif J. , Frische S. , Wang T. , Mayntz D.
Published: May 2012

Dietary protein restriction in pregnant females reduces offspring birth weight and increases the risk of developing obesity, type 2 diabetes and cardiovascular disease. Despite these grave consequences, few studies have addressed the effects of preconceptional maternal malnutrition. Here we investigate how a preconceptional low-protein (LP) diet affects offspring body mass and insulin-regulated glucose metabolism. Ten-week-old female mice (C57BL/6JBom) received either an LP or isocaloric control diet (8% and 22% crude protein, respectively) for 10 weeks before conception, but were thereafter fed standard laboratory chow (22.5% crude protein) during pregnancy, lactation and offspring growth. When the offspring were 10 weeks old, they were subjected to an intraperitoneal glucose tolerance test (GTT), and sacrificed after a 5-day recovery period to determine visceral organ mass. Body mass of LP male offspring was significantly lower at weaning compared with controls. A similar, nonsignificant, tendency was observed for LP female offspring. These differences in body mass disappeared within 1 week after weaning, a consequence of catch-up growth in LP offspring. GTTs of 10-week-old offspring revealed enhanced insulin sensitivity in LP offspring of both sexes. No differences were found in body mass, food intake or absolute size of visceral organs of adult offspring. Our results indicate that maternal protein restriction imposed before pregnancy produces effects similar to postconceptional malnutrition, namely, low birth weight, catch-up growth and enhanced insulin sensitivity at young adulthood. This could imply an increased risk of offspring developing lifestyle-acquired diseases during adulthood.
Maternal folate, alcohol and energy metabolism-related gene polymorphisms and the risk of recurrent pregnancy loss
Authors: Sata F. , Yamada H. , Kishi R. , Minakami H.
Published: May 2012

Epidemiological studies have suggested that the condition of recurrent pregnancy loss (RPL) may be multifactorial, with both genetic predisposition and environmental factors potentially involved in its pathogenesis. The aim of this study is to elucidate the associations between maternal folate, alcohol and energy metabolism-related gene polymorphisms and the risk of RPL. This case–control study, which involved 116 cases with two or more instances of RPL and 306 fertile controls, was performed in the city of Sapporo, Japan. The associations between eight single nucleotide polymorphisms of folate, alcohol and energy metabolism-related genes [methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR), alcohol dehydrogenase 1B (ADH1B), aldehyde dehydrogenase 2 (ALDH2), beta-3-adrenergic receptor (ADRB3) and peroxisome proliferator-activated receptor gamma (PPARG)], and RPL were assessed. Without consideration of cigarette smoking or alcohol use, the risk of RPL significantly decreased in women with the MTHFR rs1801133 TT, MTR rs1805087 AG or ALDH2 rs671 AA genotype (P < 0.05). The risk of RPL associated with cigarette smoking and alcohol use decreased significantly in women carrying the MTHFR rs1801133 T allele [odds ratio (OR), 0.51; 95% confidence interval (CI), 0.27–0.95]. Similarly, the risk of RPL significantly decreased in women carrying the MTR rs1805087 G allele (OR, 0.44; 95% CI, 0.23–0.85). Our findings suggest that maternal gene polymorphisms related to folate metabolism may decrease the risk of RPL. Molecular epidemiological studies are needed to unequivocally elucidate the multifactorial effects of both genetic and environmental factors on human fecundity.
Flow stagnation at Enceladus: The effects of neutral gas and charged dust
Authors: Omidi N. , Tokar R. L. , Averkamp T. , Gurnett D. A. , Kurth W. S. , Wang Z.
Published: May 2012

Enceladus is one of Saturn's most active moons. It ejects neutral gas and dust particles from its southern plumes with velocities of hundreds of meters per second. The interaction between the ejected material and the corotating plasma in Saturn's magnetosphere leads to flow deceleration in ways that remain to be understood. The most effective mechanism for the interaction between the corotating plasma and the neutral gas is charge exchange which replaces the hotter corotating ions with nearly stationary cold ions that are subsequently accelerated by the motional electric field. Dust particles in the plume can become electrically charged through electron absorption and couple to the plasma through the motional electric field. The objective of this study is to determine the level of flow deceleration associated with each of these processes using Cassini RPWS dust impact rates, Cassini Plasma Spectrometer (CAPS) plasma data, and 3‐D electromagnetic hybrid (kinetic ions, fluid electrons) simulations. Hybrid simulations show that the degree of flow deceleration by charged dust varies considerably with the spatial distribution of dust particles. Based on the RPWS observations of dust impacts during the E7 Cassini flyby of Enceladus, we have constructed a dust model consisting of multiple plumes. Using this model in the hybrid simulation shows that when the dust density is high enough for complete absorption of electrons at the point of maximum dust density, the corotating flow is decelerated by only a few km/s. This is not sufficient to account for the CAPS observation of flow stagnation in the interaction region. On the other hand, charge exchange with neutral gas plumes similar to the modeled dust plumes but with base (plume opening) densities of ∼109 cm−3 result in flow deceleration similar to that observed by CAPS. The results indicate that charge exchange with neutral gas is the dominant mechanism for flow deceleration at Enceladus.
A conceptual model of an Arctic sea
Authors: St‐Laurent P. , Straneo F. , Barber D. G.
Published: May 2012

We propose a conceptual model for an Arctic sea that is driven by river runoff, atmospheric fluxes, sea ice melt/growth, and winds. The model domain is divided into two areas, the interior and boundary regions, that are coupled through Ekman and eddy fluxes of buoyancy. The model is applied to Hudson and James Bays (HJB, a large inland basin in northeastern Canada) for the period 1979–2007. Several yearlong records from instruments moored within HJB show that the model results are consistent with the real system. The model notably reproduces the seasonal migration of the halocline, the baroclinic boundary current, spatial variability of freshwater content, and the fall maximum in freshwater export. The simulations clarify the important differences in the freshwater balance of the western and eastern sides of HJB. The significant role played by the boundary current in the freshwater budget of the system, and its sensitivity to the wind‐forcing, are also highlighted by the simulations and new data analyses. We conclude that the model proposed is useful for the interpretation of observed data from Arctic seas and model outputs from more complex coupled/climate models.
Complementary use of passive and active remote sensing for detection of penetrating convection from CloudSat, CALIPSO, and Aqua MODIS
Authors: Young Alisa H. , Bates John J. , Curry Judith A.
Published: May 2012

The study examines penetrating deep convection (PDC), that reach ∼14 km (PDC14) and ∼17 km (PDC17), using 1 year of colocated CloudSat, CALIPSO, and Aqua‐MODIS observations. The combination of multisensory and multispectral observations is used to examine how well PDC14(17) are captured using cold cloud features (CCFs), defined as groupings of 1 km MODIS pixels with ∼11μm brightness temperature (BT) less than or equal to 210 K and 235 K and positive brightness temperature differences (+BTD) between ∼6.7 μm (BT6.7) and ∼11 μm (BT11). Cross‐comparison of PDC14 with CCFs ≤ 210 K and +BTD signatures according to date, time, and geolocation show that within the tropics 61% (55%) of CCFs ≤ 210 K (+BTD) occur as PDC14. In the case of CCFs ≤ 210 K, ∼27% of the PDC14 distribution also occur as cold altostratus/anvil clouds. Results show that 50–59% of PDC14 are large enough to be detected from IR observations with a horizontal resolution of 5 km. Although observations are sampled along CloudSat's narrow swath where CloudSat/CALIPSO and Aqua MODIS observations are colocated, the study provides statistical evidence supporting the use of IR observations to study the long‐term temporal and spatial variability of high reaching deep convective cloud activity.
Study of unusual atmospheric icing at Mount Zao, Japan, using the Weather Research and Forecasting model
Authors: Podolskiy Evgeny Andreevich , Nygaard Bjørn Egil Kringlebotn , Nishimura Kouichi , Makkonen Lasse , Lozowski Edward Peter
Published: May 2012

A mesoscale atmospheric model, the Weather Research and Forecasting model (WRF), was used for a case study that reconstructs mid‐spring episodes of rime formation at Mt. Zao, Japan. One particularly interesting and rare form of rime was observed. The formations were feathery, opaque aggregates of granular ice 15–30 cm long, called “shrimp tails” in Japanese. Based on an analysis of model‐generated results, we find good quantitative agreement of modeled and observed wind and temperature time series at Jizosancho ropeway station. We identified two icing events (lasting for 36 and 41 h respectively, with surface air temperatures between −6.3° and −0.1°C, relatively constant westerly winds up to 26 m s−1, and maximum cloud liquid water contents (LWC) between 0.72 and 1.05 g m−3). We confirmed that high‐resolution modeling (1.1 km grid spacing) was much more accurate than simulations with coarser grids (10 and 3.3 km). The LWC during the formation period of this rare type of icing was estimated for the first time using the WRF model at Mt. Zao, and it was found to be up to several times higher than values previously used in experimental studies. We found that the joint wind speed‐air temperature distribution for this type of “tail” rime was more similar to that of a hard rime or glaze, than to a soft rime. We explain the formation of “shrimp tails” by wind impact angle and report previously made laboratory results on its effect on the droplet collision efficiency and the density of rime ice.
Intercomparison of temperature and precipitation data sets based on observations in the Mediterranean and the Middle East
Authors: Tanarhte M. , Hadjinicolaou P. , Lelieveld J.
Published: May 2012

This paper presents an intercomparison and evaluation of gridded temperature and precipitation data sets, based on observations in the Mediterranean and the Middle East region. Using available global and regional data, we investigate the spatial and seasonal distributions of these two parameters, including uncertainties and trends for eight subregions that signify distinct climate regimes. All data sets represent the overall spatial features well though partly with biases. Using the seasonal means, standard deviations and cumulative density functions for the eight subregions, we identify outliers among the data sets. The correlations between data sets are high except for some regional data products. Desert areas such as Saudi Arabia and Libya‐Egypt appear problematic due to their sparse station network. Similar upward trends of temperature and downward trends in precipitation are found for most of the region in all data sets, while differences appear in their magnitude and level of significance.
WRF simulations of convectively generated gravity waves in opposite QBO phases
Authors: Evan S. , Alexander M. Joan , Dudhia J.
Published: May 2012

In this study, the Weather Research and Forecasting (WRF) model is used to assess gravity wave forcing of the Quasi‐Biennial Oscillation (QBO) in January‐February 2006 and 2007. The model domain is configured as a tropical channel with a horizontal grid‐spacing of 37 km and a top at 0.1 hPa. The European Centre for Medium‐Range Weather Forecasts (ECMWF) Reanalysis Interim data provide initial and boundary conditions. In these simulations a large part of the gravity wave spectrum is explicitly simulated. The model is shown to have a realistic representation of tropical precipitation variability, mean tropical ascent, and evolution of the stratospheric zonal mean wind. The high‐resolution model outputs are used to compute gravity wave forcing of the QBO. It is shown that gravity waves account for ∼60% of the total eastward forcing during the westerly shear phase and for ∼80% of the total westward forcing during the easterly shear phase. These estimates are in agreement with previous evaluations of gravity wave forcing of the QBO. In addition, wave forcing associated with large‐horizontal‐scale inertia‐gravity waves is computed. In the simulations, sufficient vertical resolution in the stratosphere is required to properly resolve large‐horizontal‐scale inertia‐gravity waves near the peak in QBO forcing. In the WRF experiments this wave type represents ∼30% of the total gravity wave forcing. This suggests that large‐horizontal‐scale inertia‐gravity waves can play an important role in the forcing of the QBO.
Offshore sediment overpressures of passive margins: Mechanisms, measurement, and models
Authors: Dugan B. , Sheahan T. C.
Published: May 2012

Fluid pressure in excess of hydrostatic equilibrium, or overpressure, in offshore environments is a widespread phenomenon that contributes to the migration and storage of fluids, solutes, and energy and to the potential mechanical instability of these sediments. Overpressure exists in deep and shallow systems and is most likely to be found where low‐permeability (<10−16 m2) layers have inhibited pore fluid escape or there have been large forcing mechanisms (e.g., rapid sedimentation, tectonic stressing, heating, and volume‐creating reactions). The genesis and magnitude of overpressure can be controlled by physical processes (e.g., rapid sedimentation (>mm/yr), tectonic loading, and lateral fluid transfer) and thermal and chemical processes (e.g., aquathermal expansion, hydrocarbon generation, mineral diagenesis, and organic maturation). In systems where near‐lithostatic overpressures are generated, potentially unstable sediments are created. Failures of these sediments can create large‐scale natural disasters, generate fractures, and damage seafloor and subseafloor infrastructure. Detailed characterization of overpressured systems has been accomplished through geological and geotechnical analyses, including investigation of physical‐mechanical properties (mainly porosity, consolidation state, and shear strength), inversion of geophysical data (e.g., compressional and/or shear velocities), measurement of in situ properties, and postevent analyses. Process‐based models have been developed to explain the origin of overpressure in terms of rate of overpressure genesis. This allows identification of potentially unstable zones and assessment of the potential for failure. Future development in measurements and in coupling of models will lead to more accurate analysis and prediction of fluid pressure in offshore sediments, which in turn will facilitate better hazard analyses and will enable safer and more cost‐effective offshore drilling practices and other offshore infrastructure development.
The Henry semianalytical solution for saltwater intrusion with reduced dispersion
Authors: Zidane Ali , Younes Anis , Huggenberger Peter , Zechner Eric
Published: May 2012

The Henry semianalytical solution for salt water intrusion is widely used for benchmarking density dependent flow codes. The method consists of replacing the stream function and the concentration by a double set of Fourier series. These series are truncated at a given order and the remaining coefficients are calculated by solving a highly nonlinear system of algebraic equations. The solution of this system is often subject to substantial numerical difficulties. Previous works succeeded to provide semianalytical solutions only for saltwater intrusion problems with unrealistic large amount of dispersion. In this work, different truncations for the Fourier series are tested and the Levenberg‐Marquardt algorithm, which has a quadratic rate of convergence, is applied to calculate their coefficients. The obtained results provide semianalytical solutions for the Henry problem in the case of reduced dispersion coefficients and for two freshwater recharge values: the initial value suggested by Henry (1964) and the reduced one suggested by Simpson and Clement (2004). The developed semianalytical solutions are compared against numerical results obtained by using the method of lines and advanced spatial discretization schemes. The obtained semianalytical solutions improve considerably the worthiness of the Henry problem and therefore, they are more suitable for testing density dependent flow codes.
A non‐accelerating foreshock sequence followed by a short period of quiescence for a large inland earthquake
Authors: Doi Issei , Kawakata Hironori
Published: May 2012

Using continuous waveforms recorded at a seismic station located in close proximity to the epicenter of the 2008 Iwate‐Miyagi inland earthquake, we conducted a detailed investigation of foreshock behavior. Calculation of cross‐correlation coefficients between the continuous waveform record and one of the officially recognized foreshock events revealed 20 micro foreshocks in addition to the two previously recognized foreshocks. Our analysis shows that all of the foreshocks occurred within the same general area relative to the main event. Over the two week period leading up to the Iwate‐Miyagi earthquake, foreshocks only occurred during the last 45 minutes, specifically over a 35 minute period followed by a 10 minute period of quiescence just before the mainshock. We found no evidence of acceleration of the foreshock sequence.
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.
Keystone microbiome meeting 2012: a mountain top experience
Authors: Kostic Aleksandar D , Garrett Wendy S
Published: May 2012

The joint Keystone Symposia on ‘Innate Immunity and the Microbiome’ took place in March 2012 in Keystone, Colorado. Gabriel Nunez (U. Michigan, USA) and Akiko Iwasaki (Yale U., USA) organized sessions focused on innate immune sensing of microbe and damage signals, whilst Andrew Gewirtz (Georgia State U., USA), Fergus Shanahan (National U. Ireland, Ireland) and Ruth Ley (Cornell U., USA) organized the microbiome‐focused session. Joint and concurrent talks, and poster sessions between the groups, made for a sensational meeting with active exchange between participants. This meeting point is focused on the microbiome meeting talks and joint sessions.
A key structural domain of the Candida albicans Mdr1 protein
Authors: Mandal Ajeet , Kumar Antresh , Singh Ashutosh , Lynn Andrew M. , Kapoor Khyati , Prasad Rajendra
Published: May 2012

A major multidrug transporter, MDR1 (multidrug resistance 1), a member of the MFS (major facilitator superfamily), invariably contributes to an increased efflux of commonly used azoles and thus corroborates their direct involvement in MDR in Candida albicans. The Mdr1 protein has two transmembrane domains, each comprising six transmembrane helices, interconnected with extracellular loops and ICLs (intracellular loops). The introduction of deletions and insertions through mutagenesis was used to address the role of the largest interdomain ICL3 of the MDR1 protein. Most of the progressive deletants, when overexpressed, eliminated the drug resistance. Notably, restoration of the length of the ICL3 by insertional mutagenesis did not restore the functionality of the protein. Interestingly, most of the insertion and deletion variants of ICL3 became amenable to trypsinization, yielding peptide fragments. The homology model of the Mdr1 protein showed that the molecular surface-charge distribution was perturbed in most of the ICL3 mutant variants. Taken together, these results provide the first evidence that the CCL (central cytoplasmic loop) of the fungal MFS transporter of the DHA1 (drug/proton antiporter) family is critical for the function of MDR. Unlike other homologous proteins, ICL3 has no apparent role in imparting substrate specificity or in the recruitment of the transporter protein.
The intracrine renin–angiotensin system
Authors: Kumar Rajesh , Thomas Candice M. , Yong Qian Chen , Chen Wen , Baker Kenneth M.
Published: May 2012

The RAS (renin–angiotensin system) is one of the earliest and most extensively studied hormonal systems. The RAS is an atypical hormonal system in several ways. The major bioactive peptide of the system, AngII (angiotensin II), is neither synthesized in nor targets one specific organ. New research has identified additional peptides with important physiological and pathological roles. More peptides also mean newer enzymatic cascades that generate these peptides and more receptors that mediate their function. In addition, completely different roles of components that constitute the RAS have been uncovered, such as that for prorenin via the prorenin receptor. Complexity of the RAS is enhanced further by the presence of sub-systems in tissues, which act in an autocrine/paracrine manner independent of the endocrine system. The RAS seems relevant at the cellular level, wherein individual cells have a complete system, termed the intracellular RAS. Thus, from cells to tissues to the entire organism, the RAS exhibits continuity while maintaining independent control at different levels. The intracellular RAS is a relatively new concept for the RAS. The present review provides a synopsis of the literature on this system in different tissues.
Comparison of bit-patterned media fabricated by methods of direct deposition and ion-milling of cobalt/palladium multilayers
Authors: Thiyagarajah Naganivetha , Huang Tianli , Chen Yunjie , Duan Huigao , Song Debra L. Y. , Huei Leong Siang , Yang Joel K. W. , Ng Vivian
Published: May 2012

In the fabrication of bit-patterned media (BPM), two processes are commonly used, i.e., the pattern transfer by ion-milling into an underlying film of magnetic material, and the direct deposition of the magnetic material onto a pre-patterned substrate. We experimentally compared the switching performance of the BPM based on Co/Pd multilayers fabricated using these methods in terms of their switching field distribution (SFD) and physical characteristics of the bits. Our results show that both methods resulted in a narrow (∼15%) SFD at low areal recording densities of ∼0.15 Tdot/in2. However, at higher densities of up to 0.6 Tdot/in2, the SFD of the ion-milled samples detrimentally broadened to ∼30% while the BPM from the direct-deposition method maintained its narrow SFD up to a high bit density of 0.6 Tdot/in2. Our results suggest that in Co/Pd multilayer systems, the direct-deposition method, which produces more uniform bit sizes and profiles especially at high bit densities, is a more promising approach to achieving high-density BPM.
Contact resistance as a probe of near-interface ferromagnetism in GaMnAs/Cu bilayers
Authors: Eid K. F. , Paudel B. , Riley G. , Dahliah D. , Liu X. , Furdyna J. K.
Published: May 2012

We used contact resistance measurements as a sensitive probe of near-surface magnetism in GaMnAs by studying the temperature dependence of the contact resistance at Cu/GaMnAs interfaces. The specific contact resistance (ARC) has a peak that is clearly shifted towards lower temperature than that seen in GaMnAs resistivity. This shift suggests that the magnetization in the GaMnAs film is suppressed near the Cu interface. Furthermore, we show that when a native oxide layer is present between GaMnAs and Cu, the behavior of ARC is dramatically different, due to the thicker tunnel barrier at the interface.
Terahertz emission induced by optical beating in nanometer-length field-effect transistors
Authors: Nouvel P. , Torres J. , Blin S. , Marinchio H. , Laurent T. , Palermo C. , Varani L. , Shiktorov P. , Starikov E. , Gruzinskis V. , Teppe F. , Roelens Y. , Shchepetov A. , Bollaert S.
Published: May 2012

We report on photo-induced terahertz radiation with a high spectral purity generated by a submicron sized InGaAs-based high-electron-mobility transistor. The emission peak is due to the electron-hole pairs photocreated in the transistor channel at the frequency of the beating of two cw-laser sources. The radiation frequency corresponds to the lowest fundamental plasma mode in the gated region of the transistor channel. The observed high emission quality factor at 200 K is interpreted as a result of stream-plasma instability in the two-dimensional electron gas whose appearance is emphasized by the reduction of the velocity relaxation rate with the temperature.
Luminescence from two-dimensional electron gases in InAlN/GaN heterostructures with different In content
Authors: Romero M. F. , Feneberg M. , Moser P. , Berger C. , Bläsing J. , Dadgar A. , Krost A. , Sakalauskas E. , Goldhahn R.
Published: May 2012

The luminescence properties of InxAl1−xN/GaN heterostructures are investigated systematically as a function of the In content (x = 0.067 − 0.208). The recombination between electrons confined in the two-dimensional electron gas and free holes in the GaN template is identified and analyzed. We find a systematic shift of the recombination with increasing In content from about 80 meV to only few meV below the GaN exciton emission. These results are compared with model calculations and can be attributed to the changing band profile and originating from the polarization gradient between InAlN and GaN.
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

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

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

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

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

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.