bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of the gene PaEMT1 for biosynthesis of mannosylerythritol lipids in the basidiomycetous yeast Pseudozyma antarctica
Authors: Morita Tomotake , Ito Emi , Kitamoto Hiroko K. , Takegawa Kaoru , Fukuoka Tokuma , Imura Tomohiro , Kitamoto Dai
Published: June 2010

The yeast Pseudozyma antarctica produces a large amount of glycolipid biosurfactants known as mannosylerythritol lipids (MELs), which show not only excellent surface‐active properties but also versatile biochemical actions. To investigate the biosynthesis of MELs in the yeast, we recently reported expressed sequence tag (EST) analysis and estimated genes expressing under MEL production conditions. Among the genes, a contiguous sequence of 938 bp, PA_004, showed high sequence identity to the gene emt1, encoding an erythritol/mannose transferase of Ustilago maydis, which is essential for MEL biosynthesis. The predicted translation product of the extended PA_004 containing the two introns and a stop codon was aligned with Emt1 of U. maydis. The predicted amino acid sequence shared high identity (72%) with Emt1 of U. maydis, although the amino‐terminal was incomplete. To identify the gene as PaEMT1 encoding an erythritol/mannose transferase of P. antarctica, the gene‐disrupted strain was developed by the method for targeted gene disruption, using hygromycin B resistance as the selection marker. The obtained ΔPaEMT1 strain failed to produce MELs, while its growth was the same as that of the parental strain. The additional mannosylerythritol into culture allowed ΔPaEMT1 strain to form MELs regardless of the carbon source supplied, indicating a defect of the erythritol/mannose transferase activity. Furthermore, we found that MEL formation is associated with the morphology and low‐temperature tolerance of the yeast. Copyright © 2010 John Wiley & Sons, Ltd.
Surgical Approaches to the Distal Radius
Authors: Ilyas Asif M.
Published: June 2010

Introduction

Fractures of the distal radius are among the most common fractures seen. They encompass a myriad of presentations and fracture patterns that often benefit from various open reduction and internal fixation techniques—including volar plating, dorsal plating, radial plating, intramedullary nailing, and fragment-specific fixation. In order to obtain optimal reduction of these fractures, surgeons require a thorough understanding of the anatomy and various surgical exposures.

Anatomy

The distal radius is surrounded by a soft tissue envelope rich in vascularity and cutaneous innervation. The osseous surface consists of two articular surfaces and three cortical sides covered almost entirely by soft tissue.

Surgical approaches

Approaches to the distal radius can be broadly divided into volar, radial, and dorsal. Visualization of the articular surface can be accomplished best arthroscopically. Arthroscopy can be performed alone or in conjunction with other open approaches to the distal radius.

This article will review the pertinent anatomy and various surgical approaches in order to facilitate the surgeon's ability to safely expose a distal radius fracture.
Mindfulness-based cognitive therapy for bipolar disorder: A feasibility trial
Authors: Weber B. , Jermann F. , Gex-Fabry M. , Nallet A. , Bondolfi G. , Aubry J.-M.
Published: June 2010

Background

The present open study investigates the feasibility of Mindfulness-based cognitive therapy (MBCT) in groups solely composed of bipolar patients of various subtypes. MBCT has been mostly evaluated with remitted unipolar depressed patients and little is known about this treatment in bipolar disorder.

Methods

Bipolar outpatients (type I, II and NOS) were included and evaluated for depressive and hypomanic symptoms, as well as mindfulness skills before and after MBCT. Patients’ expectations before the program, perceived benefit after completion and frequency of mindfulness practice were also recorded.

Results

Of 23 included patients, 15 attended at least four MBCT sessions. Most participants reported having durably, moderately to very much benefited from the program, although mindfulness practice decreased over time. Whereas no significant increase of mindfulness skills was detected during the trial, change of mindfulness skills was significantly associated with change of depressive symptoms between pre- and post-MBCT assessments.

Conclusions

MBCT is feasible and well perceived among bipolar patients. Larger and randomized controlled studies are required to further evaluate its efficacy, in particular regarding depressive and (hypo)manic relapse prevention. The mediating role of mindfulness on clinical outcome needs further examination and efforts should be provided to enhance the persistence of meditation practice with time.
Targeting breast cancer stem cells
Authors: McDermott Sean P. , Wicha Max S.
Published: June 2010

The cancer stem cell (CSC) hypothesis postulates that tumors are maintained by a self‐renewing CSC population that is also capable of differentiating into non‐self‐renewing cell populations that constitute the bulk of the tumor. Although, the CSC hypothesis does not directly address the cell of origin of cancer, it is postulated that tissue‐resident stem or progenitor cells are the most common targets of transformation. Clinically, CSCs are predicted to mediate tumor recurrence after chemo‐ and radiation‐therapy due to the relative inability of these modalities to effectively target CSCs. If this is the case, then CSC must be efficiently targeted to achieve a true cure. Similarities between normal and malignant stem cells, at the levels of cell‐surface proteins, molecular pathways, cell cycle quiescence, and microRNA signaling present challenges in developing CSC‐specific therapeutics. Approaches to targeting CSCs include the development of agents targeting known stem cell regulatory pathways as well as unbiased high‐throughput siRNA or small molecule screening. Based on studies of pathways present in normal stem cells, recent work has identified potential “Achilles heals” of CSC, whereas unbiased screening provides opportunities to identify new pathways utilized by CSC as well as develop potential therapeutic agents. Here, we review both approaches and their potential to effectively target breast CSC.
Effects of Etiology on Inpatient Rehabilitation Outcomes in 65‐ to 74‐Year‐Old Patients With Incomplete Paraplegia From a Nontraumatic Spinal Cord Injury
Authors: Kay Elizabeth , Deutsch Anne , Chen David , Manheim Larry , Rowles Diane
Published: June 2010

Objective

To examine differences in rehabilitation outcomes for older patients with a nontraumatic spinal cord injury (NT‐SCI) for 5 etiologic diagnoses: degenerative spinal disease (DSD), malignant spinal tumor, benign spinal tumor, vascular ischemia, and spinal abscess.

Design

Retrospective cohort study that used Medicare claims and assessment data.

Setting

A total of 479 inpatient rehabilitation hospitals and units.

Patients

A total of 1780 Medicare beneficiaries (65‐74 years old) with incomplete paraplegia attributable to NT‐SCI who were discharged from inpatient rehabilitation facilities from 2002 through 2005.

Interventions

Not applicable.

Main Outcome Measures

Length of stay, discharge Functional Independence Measure (FIM) instrument motor item and subscale scores, and discharge destination.

Results

Demographic characteristics varied by etiology group. Mean ± SD rehabilitation stays ranged from 13.3 ± 7.7 days for DSD to 26.4 ± 13.4 days for vascular ischemia. Adjusted data showed stays differed (P < .001) across etiology groups. Adjusted discharge mean self‐care and mobility subscores revealed that patients with DSD and benign tumor were more independent (P < .001) than patients with a malignant tumor or spinal abscess. Patients with vascular ischemia were more dependent (P < .01) in mobility than the DSD and benign tumor groups. Etiologic differences (P < .01) in independence in discharge FIM modifiers for walking (FIM ≥ 4), bladder (FIM ≥ 6) and bowel management (FIM ≥ 6) and bowel accidents/continence (FIM ≥ 6), but not bladder accidents (FIM ≥ 6), were present. The percent of patients discharged to a community residence ranged from 59.3% to 92.6%. Adjusted data showed that significantly larger percentages (P < .01) of patients in the DSD and malignant tumor groups than in the spinal abscess group were discharged to a community residence (versus nursing home).

Conclusion

There are etiologic differences in demographics, rehabilitation length of stay, functional outcomes, and discharge destination in elderly patients with NT‐SCI.
Anxiety Levels, Fear‐avoidance Beliefs, and Disability Levels at Baseline and at 1 Year among Subjects with Acute and Chronic Low Back Pain
Authors: Newcomer Karen L. , Shelerud Randy A. , Vickers Douglas Kristin S. , Larson Dirk R. , Crawford Brianna J.
Published: June 2010

Objective

To compare anxiety levels, fear‐avoidance beliefs, and disability levels over 1 year for patients with acute (≤3 months) and chronic (>3 months) low back pain (LBP).

Design

Prospective study with questionnaire measurements.

Setting

Tertiary care clinic.

Patients

Patients with acute or chronic LBP who resided in a 3‐county local area and presented to our clinic for initial evaluation.

Methods

Administration of and results analysis from Fear‐Avoidance Beliefs Questionnaire, Oswestry Disability Index, Pain and Impairment Relationship Scale, and Spielberger State‐Trait Anxiety Inventory at baseline and 12 months. Trait anxiety was measured at baseline only.

Main Outcome Measurements

Scores from questionnaires assessing fear‐avoidance beliefs and state and trait anxiety, as well as LBP disability levels.

Results

In total, 138 patients with acute LBP and 107 with chronic LBP were enrolled. Of these patients, 111 with acute and 86 with chronic LBP completed the study. The 2 groups were statistically indistinguishable at baseline on all measures except trait anxiety scores, which were significantly higher in the group with chronic LBP than in the acute group (P = .01). At 1 year, the acute group had a statistically significant improvement in all outcome measures except state anxiety. The group with chronic LBP had significant improvement in all measures except fear‐avoidance beliefs and state anxiety. Overall, the group with acute LBP improved more in all measurement instruments than the chronic LBP group (a statistically significant difference) except state anxiety.

Conclusions

The group with chronic LBP exhibited a higher level of trait anxiety at baseline than those with acute LBP and, unlike the acute LBP group, did not have improved fear‐avoidance beliefs over 1 year. The relationship between anxiety and chronic LBP is novel. Because anxiety is potentially modifiable, future studies that evaluate the relationship between LBP and anxiety are warranted.
The types and genesis of ophicalcites in Lower Devonian olistostromes at cobalt-bearing massive sulfide deposits in the West Magnitogorsk paleoisland arc (South Urals)
Authors: Artemyev D.A. , Zaykov V.V.
Published: June 2010

Ophicalcites were earlier found in the Lower Devonian olistostromes overlapping cobalt-bearing massive sulfide deposits in the ultramafic rocks of the West Magnitogorsk paleoisland arc. They are composed of angular clastics of serpentinites and carbonates few millimeters to several centimeters in size, which are cemented with hematite-calcite and quartz-hematite-calcite matrix with aragonite, magnesite, and siderite admixtures. In chemical composition Cr-spinels from serpentinites of the ophicalcites are similar to those from the underlying serpentinites and are suprasubduction products of active continental margins. The 13C/12C and 18O/16O ratios of calcite from the breccia matrix are typical of hydrothermal deposits and are close to those of carbonate in sulfide ores and talc-carbonate metasomatites. Study of fluid inclusions from the calcite cement has shown that the ophicalcites formed from low- to moderate-temperature (100–280 °C) hydrothermal fluids as a result of postore hydrothermal emanations on ultramafic seafloor rocks similar to modern hydrothermal fields in MORs and island arcs. Hydrothermal and tectonosedimentation processes in the roof of ultramafic massifs at the vents of hydrothermal fluids led to erosion, redeposition, and cementation of ophicalcites of four types. The subsequent tectonic and gravitational processes resulted in their denudation and accumulation in olistostromes.
Integration, Cohesion and National Identity: Theoretical Reflections on Recent British Policy
Authors: Mason Andrew
Published: June 2010

Recent policy documents in Britain that have emphasized the importance of integration can be understood as addressing the question of what conditions are required in order to achieve and sustain a just society. The answer they give is that minority cultural groups need to be integrated into society, and that this involves community cohesion, secured through ‘meaningful contact’, and sharing a national identity based on common values. Here, it is argued that although meaningful contact between members of different cultural groups may promote trust between them, this does not warrant the key role which has been given to the idea of community cohesion. It is suggested instead that policies should aim to foster a widespread sense of belonging to the polity, and that this is not the same as sharing a national identity.
Secularism, Sovereignty, Indeterminacy: Is Egypt a Secular or a Religious State?
Authors: Agrama Hussein Ali
Published: June 2010

In this essay I offer a thesis about secularism as a modern historical phenomenon, through a consideration of state politics, law, and religion in contemporary Egypt. Egypt seems hardly a place for theorizing about modern secularity. For it is a state where politics and religion seem to constantly blur together, giving rise to continual conflict, and it thus seems, at best, only precariously secular. These facts, however, go to the heart of my thesis: that secularism itself incessantly blurs together religion and politics, and that its power relies crucially upon the precariousness of the categories it establishes. Egypt's religious-political ambiguities, I argue, are expressions of deeper indeterminacies at the very foundation of secular power. In what follows, I elaborate my thesis, how it differs from other, similar sounding arguments, and the shift in perspective on secularism that it entails. I begin with a famous Egyptian apostasy case.
English Law, Brahmo Marriage, and the Problem of Religious Difference: Civil Marriage Laws in Britain and India
Authors: Chatterjee Nandini
Published: June 2010

On the face of it, civil marriage represents both the most typical and most anodyne aspect of modern law. One might say that by instituting civil marriage, a bureaucratic, enumerative, and secularized state permits its subjects absolute individual choice of marital partners, and concurrently, by refusing to take into account the religious affiliation of any party, grants total freedom of religious faith. As such, it may be seen as a quintessentially modern phenomenon, connected through the adjective “civil” with other distinctively modern concepts such as civil society, all of which point to a notion of individual liberty, predicated upon a modern state guaranteeing the autonomy of large arenas of social life.
Full conserving dielectric function for plasmas at any degeneracy
Authors: Barriga-Carrasco Manuel D.
Published: June 2010

Dielectric functions of an electron plasma are calculated for an electron gas in which number, momentum, and energy are conserved during electron-electron collisions. They are compared with others in the literature, revealing that, in general, that imposition of the conservation laws tends to make the full conserving dielectric response more similar to the random phase approximation dielectric response than without it. This is due to the fact that in the random phase approximation model all the conservation laws are also enforced. Our model is checked for other plasma degeneracies; concretely we consider partially degenerate plasmas and classical plasmas. The behaviour of the dielectric functions of these plasmas is similar to the degenerate one. Differences among dielectric functions are more significant than for the degenerate case, but it is mainly due to low relaxation time values. The most relevant issue for these plasmas is the fact that the consideration of energy conservation in the dielectric function is more important in these cases, because plasma temperature is significant.
Resonant third harmonic generation of an infrared laser in a semiconductor wave guide
Authors: Garg Vijay , Tripathi V.K.
Published: June 2010

An infrared laser propagating through a semiconductor waveguide, embedded with a density ripple of wave number q, resonantly excites third harmonic radiation. The phase matching is achieved when q equals difference between third harmonic wave number and three times the wave number of the laser. The excited third harmonic is in higher order radial Eigen mode than the pump laser. The third harmonic efficiency increases with electron concentration and decreases with the frequency of the laser.
Optimization for deuterium ion acceleration in foam targets by ultra-intense lasers
Authors: Bari M.A. , Sheng Z.M. , Wang W.M. , Li Y.T. , Salahuddin M. , Nasim M.H. , Naz G. Shabbir , Gondal M.A. , Zhang J.
Published: June 2010

In this article, we investigate the effects of foam target composition and laser parameters on deuterium ion energy spectra with particle-in-cell simulations. We find that localized electrostatic fields with multi peaks around the surfaces of lamellar layers inside foam target are induced. These fields accelerate deuterium ions from thin foam layers by restricting the flow of hot electrons. This mechanism of ion acceleration called as bulk ion acceleration generates large number of high energy deuterium ions. Deuterons inside foam target are accelerated up to 126 MeV in case of oblique optimal angle of 30° where it is much greater than the normal laser incidence energy of 88 MeV.
Is Chinese Education Underfunded?
Authors: Kipnis Andrew , Li Shanfeng
Published: June 2010

Scholarship on education in China has correctly emphasized the massive inequalities in reform era educational funding. In describing these inequalities, however, scholars have made dubious claims about the supposedly low level of funding for education in China in relation to other countries. In this article, we examine the statistics on which this claim is based and detail the ways in which education is funded in China that do not get counted in the statistics. We conclude that though funding for education in China is unequal, the total level of such funding may not be low. Moreover, the official statistics are not a reliable guide to comparative discussions of educational funding.
Affirmative Action, Economic Reforms, and Han–Uyghur Variation in Job Attainment in the State Sector in Urumchi
Authors: Zang Xiaowei
Published: June 2010

Have workers of minority status suffered labour market discrimination in China? Do all actors in the state sector discriminate against minority workers? What are the rationales for discrimination? To address these questions, I compare two ethnic groups (Han Chinese and Uyghur) with regard to job attainment in the state sector. Data are from a 2005 survey (N = 2,947) conducted in Ürümchi, China. Data analysis shows that controlling background characteristics does not remove the Uyghur–Han difference in job attainment in state firms. However, there is no ethnic variation in employment in redistributive agencies. This contrast is explained with reference to post-1978 market transition and the resulting differentiation in the institutional tasks between state firms and government agencies.
Joseph Soloveitchik and Immanuel Kant's Mitzvah-Aesthetic
Authors: Braiterman Zachary
Published: June 2010

In the following pages, I will address the relationship between Jewish thought and aesthetics by bringing Joseph Soloveitchik into conversation with Immanuel Kant, whose Critique of Judgment remains an imposing monument in the history of philosophical aesthetics. While Buber and Rosenzweig may have been more accomplished aesthetes, Soloveitchik's aesthetic proves closer to Kant's own. In particular, I draw upon the latter's distinction between the beautiful and the sublime and the notion of a form of indeterminate purposiveness without determinate purpose. I will relate these three figures to Soloveitcchik's understanding of halakhah and to the ideal of performing commandments for their own sake (li-shemah). The model of mitzvah advanced by this comparison is quintessentially modern: an autonomous, self-contained, formal system that does not (immediately) point to extraneous goods, such as spiritual enlightenment, personal morality, or social ethics. The good presupposed by this system proves first and foremost “aesthetic.” That is, immanent to the system. Supererogatory goods enter into the picture only afterward as second-order effects.
OPTIMAL FILTERING IN DISCRETE-TIME SYSTEMS WITH TIME DELAYS AND MARKOVIAN JUMP PARAMETERS
Authors: HAN CHUNYAN , ZHANG HUANSHUI
Published: June 2010

This paper investigates the linear minimum mean-square error estimation for discrete-time Markovian jump linear systems with delayed measurements. The key technique applied for treating the measurement delay is reorganization innovation analysis, by which the state estimation with delayed measurements is transformed into a standard linear mean-square filter of an associated delay-free system. The optimal filter is derived based on the innovation analysis method together with geometric arguments in an appropriate Hilbert space. The solution is given in terms of two Riccati difference equations. Finally, a simulation example is presented to illustrate the efficiency of the proposed method.
The endogenous origins of experience, routines, and organizational capabilities: the poverty of stimulus
Authors: FELIN TEPPO , FOSS NICOLAI J.
Published: June 2010

In this paper we discuss the origins and emergence of organizational routines and capabilities. We first argue that there are theoretical and endogeneity-related concerns associated with the key antecedents and mechanisms specified by the extant routines and capabilities literature. Specifically, we explicate the behaviorist and empiricist foundations of the organizational routines and capabilities literature and the extant emphasis placed on experience, repetition, and observation as the key antecedents and mechanisms of routines and capabilities. Based on this discussion we highlight several, endogeneity-related concerns, namely: (1) the problem of origins and causation, (2) the problem of extremes, (3) the problem of intentionality, (4) the problem of new knowledge, and (5) the problem of the environment. We introduce the ‘poverty of stimulus’ argument and discuss how an internalist or rationalist, choice-based approach can provide a more fruitful (though preliminary) foundation for understanding organizational behavior and capabilities.
Between rhetoric and reality: exploring the impact of military humanitarian intervention upon sexual violence – post-conflict sex trafficking in Kosovo
Authors: Godec Samantha T.
Published: June 2010

Adopting a feminist perspective, this paper analyses the doctrine of humanitarian intervention and its impact on women in recipient states, particularly with regard to sexual violence. By analysing the phenomenon of post-conflict trafficking in Kosovo following the NATO intervention, the author presents a challenge to the ‘feminist hawks’ who have called for military intervention in situations of systematic sexual violence. It is the author's contention that such intervention would be counterproductive for women's rights and thus constitute a disproportionate response to sexual violence in terms of the international law governing the use of force.
‘They came with two guns’: the consequences of sexual violence for the mental health of women in armed conflicts
Authors: Josse Evelyne
Published: June 2010

Sexual violence has serious and multiple consequences for the mental health of women. At the psychological level, it leads to radical changes in the image that the victim has of herself, in her relations with her immediate social circle and beyond, in the community as a whole, and in the way in which the victim sees the past, present, and future. It thus has a lasting negative impact on the victim's perception of herself, of events, and of others. At the community level, it stigmatizes the victim, depriving her of any social status or intrinsic value as a person (she is seen as unfaithful or promiscuous), and thereby modifies relationships within the community with an overall deleterious effect. This article discusses these consequences of sexual violence for the mental health of women, especially those who are its victims during armed conflicts.
Thin and intermittent ultralow‐velocity zones
Authors: Rost Sebastian , Garnero Edward J. , Stefan Wolfgang
Published: June 2010

An area of the core‐mantle boundary to the east of Australia is investigated for the existence of ultralow‐velocity zones (ULVZs). High‐frequency recordings of deep Vanuatu and Tonga‐Fiji earthquakes are studied from the small‐aperture Warramunga Seismic Array in central Australia. The Tonga‐Fiji data were used in a previous ULVZ study, while earthquakes from the Vanuatu subduction zone were newly collected for this study. Core‐reflected ScP waves were analyzed, which possess observable precursory and postcursory arrivals in the presence of ULVZ structure. We apply a total variation deconvolution algorithm to our data, which significantly sharpens observed signals, hence, increasing our vertical resolution and therefore allowing us to detect thinner ULVZs than previously possible. The minimum ULVZ thickness detection threshold is approximately 2–3 km with this method. This data set samples a spot at the boundary of the large low shear velocity province beneath the Pacific. The new analysis provides evidence for a 5–6 km thick ULVZ to the north of a previously detected 8.5 km thick ULVZ. A second sampled region shows evidence for an even thinner ULVZ structure, with thicknesses of ∼3 km. These findings are largely consistent with the hypothesis that ULVZs are most likely to be found along the inside margin of large low shear velocity regions that have been attributed to dense, chemically distinct material.
Internal‐tide energy over topography
Authors: Kelly S. M. , Nash J. D. , Kunze E.
Published: June 2010

The method used to separate surface and internal tides ultimately defines properties such as internal‐tide generation and the depth structure of internal‐tide energy flux. Here, we provide a detailed analysis of several surface‐/internal‐tide decompositions over arbitrary topography. In all decompositions, surface‐tide velocity is expressed as the depth average of total velocity. Analysis indicates that surface‐tide pressure is best expressed as the depth average of total pressure plus a new depth‐dependent profile of pressure, which is due to isopycnal heaving by movement of the free surface. Internal‐tide velocity and pressure are defined as total variables minus the surface‐tide components. Corresponding surface‐ and internal‐tide energy equations are derived that contain energy conversion solely through topographic internal‐tide generation. The depth structure of internal‐tide energy flux produced by the new decomposition is unambiguous and differs from that of past decompositions. Numerical simulations over steep topography reveal that the decomposition is self‐consistent and physically relevant. Analysis of observations over Kaena Ridge, Hawaii; and the Oregon continental slope indicate O (50 W m−1) error in depth‐integrated energy fluxes when internal‐tide pressure is computed as the residual of pressure from its depth average. While these errors are small at major internal‐tide generation sites, they may be significant where surface tides are larger and depth‐integrated fluxes are weaker (e.g., over continental shelves).
On the surface circulation in the western Coral Sea and residence times in the Great Barrier Reef
Authors: Choukroun Séverine , Ridd Peter V. , Brinkman Richard , McKinna Lachlan I. W.
Published: June 2010

Surface velocity observations from satellite tracked drifters made between 1987 and 2008 were used to resolve the surface circulation of the western Coral Sea, west of 158°E, and the Great Barrier Reef (GBR). The mean surface current map depicts well the major circulation patterns of the region, such as the position of the north Vanuatu and north Caledonia jets (NVJ and NCJ) and the western boundary currents. The North Queensland Current (NQC) and the East Australian Current (EAC) are well defined, flowing at speeds greater than 50 cm s−1 to the north, south of 15°S and 19°S, respectively. The NQC/EAC is mainly formed by the NVJ/NCJ flows, respectively. The presence of the Queensland Plateau greatly affects the westward flow, causing a zone of weak and highly variable currents that extends from 15°S to 18°S between the Queensland Plateau and the GBR shelf. Of the 235 drifters that crossed the western Coral Sea, 75 entered the GBR. Analysis of the drifter trajectories inside the GBR reveals the presence of a northwestward circulation at speeds of 22 cm s−1 north of 18°S and 0.5 cm s−1 south of 18°S. Drifter travel times used to evaluate the water residence times within the GBR indicate residence times of a few weeks for most of the lagoon.
Evaluating the controls of shear stress, sediment supply, alluvial cover, and channel morphology on experimental bedrock incision rate
Authors: Johnson Joel P. L. , Whipple Kelin X.
Published: June 2010

We explored the dependence of experimental bedrock erosion rate on shear stress, bed load sediment flux, alluvial bed cover, and evolving channel morphology. We isolated these variables experimentally by systematically varying gravel sediment flux Qs and water discharge Qw in a laboratory flume, gradually abrading weak concrete “bedrock.” All else held constant, we found that (1) erosion rate was insensitive to flume‐averaged shear stress, (2) erosion rate increased linearly with sediment flux, (3) erosion rate decreased linearly with the extent of alluvial bed cover, and (4) the spatial distribution of bed cover was sensitive to local bed topography, but the extent of cover increased with Qs/Qt (where Qt is flume‐averaged transport capacity) once critical values of bed roughness and sediment flux were exceeded. Starting from a planar geometry, erosion increased bed roughness due to feedbacks between preferential sediment transport through interconnected topographic lows, focused erosion along these zones of preferential bed load transport, and local shear stresses that depended on the evolving bed morphology. Finally, continued growth of bed roughness was inhibited by imposed variability in discharge and sediment flux, due to changes in spatial patterns of alluvial deposition and impact wear. Erosion was preferentially focused at lower bed elevations when the bed was cover‐free, but was focused at higher bed elevations when static alluvial cover filled topographic lows. Natural variations in discharge and sediment flux may thus stabilize and limit the growth of roughness in bedrock channels due to the effects of partial bed cover.
Fresh powder on Waddington's slopes
Authors: Fisher Amanda G , Merkenschlager Matthias
Published: June 2010

The Keystone Symposium on Stem Cell Differentiation and Dedifferentiation attracted nearly 500 participants affiliated with academia, the biotechnology industry, scientific publishing and clinical practice. This broad group examined current advances in stem‐cell biology, with a particular focus on induced pluripotent stem cells, and discussed both their potential and limitations in therapeutic applications.
Substrate-specific binding and conformational changes involving Ser313 and transmembrane domain 8 of the human reduced folate carrier, as determined by site-directed mutagenesis and protein cross-linking
Authors: Hou Zhanjun , Wu Jianmei , Ye Jun , Cherian Christina , Matherly Larry H.
Published: June 2010

RFC (reduced folate carrier) is the major transporter for reduced folates and antifolates [e.g. MTX (methotrexate)]. RFC is characterized by two halves, each with six TMD (transmembrane domain) α helices connected by a hydrophilic loop, and cytoplasmic N- and C-termini. We previously identified TMDs 4, 5, 7, 8, 10 and 11 as forming the hydrophilic cavity for translocation of (anti)folates. The proximal end of TMD8 (positions 311–314) was implicated in substrate binding from scanning-cysteine accessibility methods; cysteine replacement of Ser313 resulted in loss of transport. In the present study, Ser313 was mutated to alanine, cysteine, phenylalanine and threonine. Mutant RFCs were expressed in RFC-null R5 HeLa cells. Replacement of Ser313 with cysteine or phenylalanine abolished MTX transport, whereas residual activity was preserved for the alanine and threonine mutants. In stable K562 transfectants, S313A and S313T RFCs showed substantially decreased Vmax values without changes in Kt values for MTX compared with wild-type RFC. S313A and S313T RFCs differentially impacted binding of ten diverse (anti)folate substrates. Cross-linking between TMD8 and TMD5 was studied by expressing cysteine-less TMD1–6 (N6) and TMD7–12 (C6) half-molecules with cysteine insertions spanning these helices in R5 cells, followed by treatment with thiol-reactive homobifunctional cross-linkers. C6–C6 and N6–N6 cross-links were seen for all cysteine pairs. From the N6 and C6 cysteine pairs, Cys175/Cys311 was cross-linked; cross-linking increased in the presence of transport substrates. The results of the present study indicate that the proximal end of TMD8 is juxtaposed to TMD5 and is conformationally active in the presence of transport substrates, and TMD8, including Ser313, probably contributes to the RFC substrate-binding domain.
Interaction between endometrial epithelial cells and blood leucocytes promotes cytokine release and epithelial barrier function in response to Chlamydia trachomatis lipopolysaccharide stimulation
Authors: Ho Sze Lok , He Qiong , Chen Jie , Xu Penghui , Tsang Ling Lai , Yu Sidney , Chung Wa Yiu , Chan Chang Hsiao
Published: June 2010

Chlamydia trachomatis infection is currently the most common cause of infection‐related sterility in women. However, it remains largely unknown how uterine epithelial cells interact with recruited leucocytes in response to C. trachomatis infection in the female genital tract. To study the defence mechanism of the endometrium against C. trachomatis infection, we established an in vitro co‐culture of EEC (endometrial epithelial cells) and PBL (peripheral blood leucocytes) isolated from mice and investigated the immune response of these cells upon C. trachomatis LPS (lipopolysaccharide) challenge using a cytokine antibody array and RT‐PCR (reverse transcription‐PCR). Our results showed that upon C. trachomatis LPS stimulation, proinflammatory cytokines/chemokines, such as TNF‐α, IL‐1β, MIPs (macrophage inflammatory proteins), IL‐12p40p70, KC, GCSFs (granulocyte colony stimulating factors), IL‐6 and TIMPs (tissue inhibition metalloproteinases) are up‐regulated and/or released from EEC–PBL co‐culture. Further, the TER (transepithelial resistance), measured by the Isc (short‐circuit current) technique was significantly increased in EEC/PBL co‐cultured cells and also when stimulated with C. trachomatis LPS compared with EEC alone. These changes appear to be mediated by the change in cytokine‐induced expression of tight junction‐related protein ZO‐1. The present results demonstrated that the epithelial–immune cross‐talk could promote the release of proinflammatory cytokines and enhance the barrier function of the endometrium against C. trachomatis infection in the female reproductive tract.
Gender Differences in Intentional Social Action: We-Intention to Engage in Social Network-Facilitated Team Collaboration
Authors: Xl Shen Aaron , Lee Matthew Ko , Cheung Christy Mk , Chen Huaping
Published: June 2010

The growth and popularity of Web 2.0 applications help people to build and maintain their social networks online and further encourage social network-facilitated team collaboration. In this study, we conceptualized the use of Instant messaging in social network-facilitated team collaboration as an Intentional social action and further Investigated the effect of gender differences In the development of we-intention (I. e. collective intention) to engage In such collaboration. A research model was developed and empirically tested with 482 university students In Mainland China. The results demonstrated that the effects of attitude, positive anticipated emotions, and group norms on we-intention were more Important for men, whereas the effects of social Identity and negative anticipated emotions were more significant for women to collectively participate In social network-facilitated team collaboration. We believe the Implications of this study would shed considerable light on both research and practice.
High frequency characterization of a Schottky contact to a GaN nanowire bundle
Authors: Chiang Chin-Jen , Wallis T. Mitch , Gu Dazhen , Imtiaz Atif , Kabos Pavel , Blanchard Paul T. , Bertness Kristine A. , Sanford Norman A. , Kim Kichul , Filipovic Dejan
Published: June 2010

A two-port GaN nanowire (NW) device with one Schottky contact and one Ohmic contact was characterized up to 10 GHz using on-wafer microwave measurements. In addition to the measurement of the broadband response, two additional applications of microwave measurements are introduced: (1) the capability to distinguish a Schottky-type contact from an Ohmic contact based on the reflected broadband signals (S11 and S22) and (2) the measurement of a capacitance voltage (CV) curve for a Schottky contact to a bundle of a few NWs. The junction capacitance of the Schottky contact is determined at various bias voltages by fitting the broadband response with a microwave circuit model. The carrier concentration is estimated from the resulting CV curve to be 5.3×1018/cm3 and the Schottky barrier height is estimated to be 0.89 eV.
Polarization-tunable chiral nematic liquid crystal lasing
Authors: Wang Chun-Ta , Lin Tsung-Hsien
Published: June 2010

A chiral nematic liquid crystal laser with arbitrarily controllable polarization was demonstrated by combining polymeric cholesteric and nematic liquid crystal films. The lasing polarization states can be continuously varied by applying voltages from 1.25 to 2 V. Right-handed circular polarization is switched to left-handed circularly polarization through −45° linearly polarized states. The trajectories of the Stokes parameters on the Poincaré sphere are used to analyze the variation in lasing polarization. The change in polarization is simulated and the simulation agrees closely with the experimental data.
Effect of strain on the growth of InAs/GaSb superlattices: An x-ray diffraction study
Authors: Li J. H. , Stokes D. W. , Wickett J. C , Caha O. , Bassler K. E. , Moss S. C.
Published: June 2010

We present a detailed x-ray diffraction study of the strain in InAs/GaSb superlattices grown by molecular beam epitaxy. The superlattices were grown with either InSb or GaAs interfaces (IFs). We show that the superlattice morphology, either planar or nanostructured, is dependent on the chemical bonds at the heterointerfaces. In both cases, the misfit strain has been determined for the superlattice layers and the IFs. We also determined how the magnitude and sign of this strain is crucial in governing the morphology of the superlattice. Our analysis suggests that the growth of self-assembled nanostructures may be extended to many systems generally thought to have too small a lattice mismatch.
Effects of TaN, Ru, and Pt electrodes on thermal stability of hafnium-based gate stacks
Authors: Kwon Jinhee , Chabal Yves J.
Published: June 2010

Potential p-FET high-work function metals, TaN, Ru, and Pt are shown to have distinct effects on the stability of Hf-based gate stacks during a thermal process. Ru and Pt promote catalytic decomposition of the underlying dielectrics, resulting in the formation of HfSix and Ru(Pt)Six at 950 (900) °C. With Ru, hydroxyl impurities are critical in silicidation which is localized in the vicinity of voids where the Si substrate is exposed through partial HfO2 and SiO2 decomposition. The degree of silicide formation is greater with Pt, occurring upon major decomposition of the underlying dielectrics with or without hydroxyl impurities. Transfer of electrons from the HfO2 oxygen vacancy to Ru and Pt may play a role in the decomposition of the dielectric films. In contrast, the thermal evolution of TaN-gate stacks is very similar to that of HfO2 stacks without any capping metal layer. With annealed HfO2 and HfO2/TaN stacks there is no detectable metal diffusion into the dielectrics, and the overall compositional stability is preserved except for the growth of interfacial SiO2.
Irregular behavior in an excitatory-inhibitory neuronal network
Authors: Park Choongseok , Terman David
Published: June 2010

Excitatory-inhibitory networks arise in many regions throughout the central nervous system and display complex spatiotemporal firing patterns. These neuronal activity patterns (of individual neurons and/or the whole network) are closely related to the functional status of the system and differ between normal and pathological states. For example, neurons within the basal ganglia, a group of subcortical nuclei that are responsible for the generation of movement, display a variety of dynamic behaviors such as correlated oscillatory activity and irregular, uncorrelated spiking. Neither the origins of these firing patterns nor the mechanisms that underlie the patterns are well understood. We consider a biophysical model of an excitatory-inhibitory network in the basal ganglia and explore how specific biophysical properties of the network contribute to the generation of irregular spiking. We use geometric dynamical systems and singular perturbation methods to systematically reduce the model to a simpler set of equations, which is suitable for analysis. The results specify the dependence on the strengths of synaptic connections and the intrinsic firing properties of the cells in the irregular regime when applied to the subthalamopallidal network of the basal ganglia.
Numerical studies of the effects of precursor plasma on the performance of wire-array Z-pinches
Authors: Ning Cheng , Sun Shun-Kai , Xiao De-Long , Zhang Yang , Ding Ning , Huang Jun , Xue Chuang , Shu Xiao-Jian
Published: June 2010

This paper is to numerically investigate, in one dimension, the effects of precursor plasma resulted from wire-array ablation on the performance of its following implosion after the ablation. The wire-array ablation is described by an analytic model, which consists of a rocket model or Sasorov’s expression of wire-array mass ablation rate, the evolution equation of magnetic field, and several roughly reasonable assumptions. The following implosion is governed by the radiation magnetohydrodynamics. The implosion processes of wire-array Z-pinch from plasma shells prefilled and un-prefilled by the low-density plasma inside them are studied, and that from the wire-array ablations, which may be changed through varying the ablation time, ablation rate, and ablation velocity Vabl, are also simulated. The obtained results reveal that the prefilled low-density plasma and the precursor plasma from the wire-array ablation help to enhance the plasma shell pinch and the final implosion of the wire array, respectively, compared to the pinch of un-prefilled plasma shell. With the same plasma masses, which are distributed in the interior of the array and the shell, and modified Spitzer resistivity, the implosions that start from the wire ablation develop faster than that from the plasma shell with the prefill. If more substance ablates from the wire array before the start of its implosion, the final Z-pinch performance could be better. The Z-pinch plasma is highly magnetized with driven current more than 3 MA.
The role of anomalous Hall effect in diluted magnetic semiconductors and oxides
Authors: Hsu H. S. , Lin C. P. , Sun S. J. , Chou H.
Published: June 2010

A serious debate has arisen in the development of spintronics regarding contradictory findings on whether or not anomalous Hall effect (AHE) represents the spin polarization nature of carriers in diluted magnetic semiconductors (DMS) and oxides (DMO). Based on our results and on the common AHE characteristics of others reports, here we suggest that only those AHEs for DMSs or DMO which match quantitatively with the magnetic hysteresis loop and which follow the 1.6 scaling relation represent the spin polarization nature of carriers. However, these criteria cannot be used to determine the percentage of magnetic precipitation or of the spin polarized current.
Atomistic simulations of mechanical properties of LaBr3 single crystals
Authors: Zhou X. W. , Doty F. P. , Yang P.
Published: June 2010

Based upon a many-body La–Br interatomic potential, molecular dynamics simulations have been performed to study mechanical properties of the UCl3 phase, LaBr3 crystal. Both plastic deformation and fracture mechanisms were explored. For plastic deformation, dislocation line energy, core structure, slip mechanism, and mobility were all examined. For fracture mechanism, tensile tests were conducted under different loading directions. We found that the ⟨0001⟩ prism dislocations have the lowest line energies (∼5 eV/Å, compared to >8 eV/Å for the ⟨112¯0⟩ basal dislocations). The ⟨0001⟩ edge dislocation is mobile and its mobility increases with temperature. The ⟨0001⟩ screw dislocation is mobile at 0 K temperature and it becomes immobile as temperature is increased. The ⟨112¯0⟩ edge and screw dislocations are always immobile at any temperatures. The mobile dislocations do not dissociate into partials and they always move in a perfect unit. The immobile dislocations, however, always exhibit nonplanar dissociated core structures. Interestingly, the slip plane of the ⟨0001⟩ edge dislocation differs from the cleavage plane by an one-atomic plane distance, whereas the slip of the ⟨0001⟩ screw dislocation is associated with alternative out-of-plane exchange of Br atoms. The critical shear stress for the onset of ⟨0001⟩ slip was found to be around 1 GPa for the edge dislocation at 300 K, and around 1.5 GPa for both edge and screw dislocations at 0 K. Tensile loading simulations indicated that the theoretical strength of the material is critically determined by the {11¯00} cleavage. The lowest theoretical strength and fracture strain occur when the loading direction is normal to the cleavage plane and the highest theoretical strength and fracture strain occur when the loading direction is parallel to the cleavage plane.
Analysis of lateral current spreading in solar cell devices by spatially-resolved electroluminescence
Authors: Xiong Kanglin , He Wei , Lu Shulong , Zhou Taofei , Jiang Desheng , Wang Rongxin , Qiu Kai , Dong Jianrong , Yang Hui
Published: June 2010

Spatially-resolved electroluminescence (EL) images from solar cells contain information of local current distribution. By theoretical analysis of the EL intensity distribution, the current density distribution under a certain current bias and the sheet resistance can be obtained quantitatively. Two-dimensional numerical simulation of the current density distribution is employed to a GaInP cell, which agrees very well with the experimental results. A reciprocity theorem for current spreading is found and used to interpret the EL images from the viewpoint of current extraction. The optimization of front electrodes is discussed based on the results.