bluuebunny/crossref_metadata_2025 huggingface dataset:
Promotion of Osteoblast Differentiation in Mesenchymal Cells Through Cbl-Mediated Control of STAT5 Activity
Authors: Dieudonne François-Xavier , Sévère Nicolas , Biosse-Duplan Martin , Weng Jing-Jie , Su Yeu , Marie Pierre J.
Published: March 2013

The identification of the molecular mechanisms controlling the degradation of regulatory proteins in mesenchymal stromal cells (MSC) may provide clues to promote MSC osteogenic differentiation and bone regeneration. Ubiquitin ligase-dependent degradation of proteins is an important process governing cell fate. In this study, we investigated the role of the E3 ubiquitin ligase c-Cbl in MSC osteoblast differentiation and identified the mechanisms involved in this effect. Using distinct shRNA targeting c-Cbl, we showed that c-Cbl silencing promotes osteoblast differentiation in murine and human MSC, as demonstrated by increased alkaline phosphatase activity, expression of phenotypic osteoblast marker genes (RUNX2, ALP, type 1 collagen), and matrix mineralization in vitro. Coimmunoprecipitation analyses showed that c-Cbl interacts with the transcription factor STAT5, and that STAT5 forms a complex with RUNX2, a master transcription factor controlling osteoblastogenesis. Silencing c-Cbl decreased c-Cbl-mediated STAT5 ubiquitination, increased STAT5 protein level and phosphorylation, and enhanced STAT5 and RUNX2 transcriptional activity. The expression of insulin like growth factor-1 (IGF-1), a target gene of STAT5, was increased by c-Cbl silencing in MSC and in bone marrow stromal cells isolated from c-Cbl deficient mice, suggesting that IGF-1 contributes to osteoblast differentiation induced by c-Cbl silencing in MSC. Consistent with these findings, pharmacological inhibition of STAT5 activity, or neutralization of IGF-1 activity, abrogated the positive effect of c-Cbl knockdown on MSC osteogenic differentiation. Taken together, the data provide a novel functional mechanism by which the ubiquitin ligase c-Cbl regulates the osteoblastic differentiation program in mesenchymal cells by controlling Cbl-mediated STAT5 degradation and activity.
Analysis of changing pan evaporation in the arid region of Northwest China
Authors: Li Zhi , Chen Yaning , Shen Yanjun , Liu Yongbo , Zhang Shuhua
Published: March 2013

Key Points

Ep decreased from 1958 to 1993 but increased since then

Ep mostly due to changes in the aerodynamic component

WS and VPD are both primary factors of the reversion of Ep
Decoding the drivers of bank erosion on the Mekong river: The roles of the Asian monsoon, tropical storms, and snowmelt
Authors: Darby Stephen E. , Leyland Julian , Kummu Matti , Räsänen Timo A. , Lauri Hannu
Published: March 2013

Key Points

IOD events have a greater effect on Mekong bank erosion than ENSO events

Snow/glacier melt and tropical storms both affect Mekong River bank erosion

Mekong flows driving bank erosion have become increasingly variable
Estimation of water retention parameters from nuclear magnetic resonance relaxation time distributions
Authors: Costabel Stephan , Yaramanci Ugur
Published: March 2013

Key Points

For sandy soils, water retention parameters can be estimated from NMR data.

NMR is sensitive for pore bodies only.

For samples with many pore constrictions, the NMR estimation must fail.
Instantaneous turbulent forces and impulse on a rough bed: Implications for initiation of bed material movement
Authors: Celik Ahmet Ozan , Diplas Panayiotis , Dancey Clint L.
Published: March 2013

Key Points

The pdf of impulse events is well described by a log normal distribution

The local streamwise velocity plays a dominant role on particle dislodgement

Wake flows increase particle entrainment via enhanced lift and increased TI
White‐tailed eagles (Haliaeetus albicilla) at the Smøla wind‐power plant, Central Norway, lack behavioral flight responses to wind turbines
Authors: Dahl Espen Lie , May Roel , Hoel Pernille Lund , Bevanger Kjetil , Pedersen Hans Chr , Røskaft Eivin , Stokke Bård G.
Published: March 2013

Evidence is increasing of bird mortality due to large‐scale wind‐energy development. Soaring raptors, such as the white‐tailed eagle (Haliaeetus albicilla), have proven particularly vulnerable to collisions. In this study, we compared white‐tailed eagle flight behavior both inside and outside of the Smøla wind‐power plant on coastal Central Norway. During the eagle breeding period (mid‐Mar–end May 2008), we collected data on flight activity (directional flight, social behavior, and soaring) and flight altitude (below, within, and above the rotor‐swept zone [RSZ]) at 12 vantage points; 6 within the wind‐power plant and 6 outside (control area). We found that white‐tailed eagles did not show any clear avoidance flight responses to the wind turbines. Hence, we found no significant differences in the total amount of flight activity within and outside the power‐plant area. However, we found less flight activity among adults than among subadults within the power plant compared with the control area. We also found a slightly increased probability of flight activity in the RSZ within the power plant, which obviously may increase the risk of collision with wind turbines. Our findings may help explain the relatively high mortality rate of white‐tailed eagles in the wind‐power‐plant area and the recorded peak in eagle fatalities during the breeding season. © 2013 The Wildlife Society.
Comparing bird and bat fatality‐rate estimates among North American wind‐energy projects
Authors: Smallwood K. Shawn
Published: March 2013

Estimates of bird and bat fatalities are often made at wind‐energy projects to assess impacts by comparing them with other fatality estimates. Many fatality estimates have been made across North America, but they have varied greatly in field and analytical methods, monitoring duration, and in the size and height of the wind turbines monitored for fatalities, and few benefited from scientific peer review. To improve comparability among estimates, I reviewed available reports of fatality monitoring at wind‐energy projects throughout North America, and I applied a common estimator and 3 adjustment factors to data collected from these reports. To adjust fatality estimates for proportions of carcasses not found during routine monitoring, I used national averages from hundreds of carcass placement trials intended to characterize scavenger removal and searcher detection rates, and I relied on patterns of carcass distance from wind turbines to develop an adjustment for variation in maximum search radius around wind turbines mounted on various tower heights. Adjusted fatality rates correlated inversely with wind‐turbine size for all raptors as a group across the United States, and for all birds as a group within the Altamont Pass Wind Resource Area, California. I estimated 888,000 bat and 573,000 bird fatalities/year (including 83,000 raptor fatalities) at 51,630 megawatt (MW) of installed wind‐energy capacity in the United States in 2012. As wind energy continues to expand, there is urgent need to improve fatality monitoring methods, especially in the implementation of detection trials, which should be more realistically incorporated into routine monitoring. © 2013 The Wildlife Society
Production of natural value-added compounds: an insight into the eugenol biotransformation pathway
Authors: Mishra Shashank , Sachan Ashish , Sachan Shashwati Ghosh
Published: March 2013

During the past few years, the production of natural value-added compounds from microbial sources has gained tremendous importance. Due to an increase in consumer demand for natural products, various food and pharmaceutical industries are continuously in search of novel metabolites obtained from microbial biotransformation. The exploitation of microbial biosynthetic pathways is both feasible and cost effective in the production of natural compounds. The environmentally compatible nature of these products is one major reason for their increasing demand. Novel approaches for natural product biogeneration will take advantage of the current studies on biotechnology, biochemical pathways and microbiology. The interest of the scientific community has shifted toward the use of microbial bioconversion for the production of valuable compounds from natural substrates. The present review focuses on eugenol biotransformation by microorganisms resulting in the formation of various value-added products such as ferulic acid, coniferyl alcohol, vanillin and vanillic acid.
In vitro read‐through of phenylalanine hydroxylase (PAH) nonsense mutations using aminoglycosides: a potential therapy for phenylketonuria
Authors: Ho Gladys , Reichardt Juergen , Christodoulou John
Published: March 2013

Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive inborn error of phenylalanine metabolism, predominantly caused by mutations in the phenylalanine hydroxylase (PAH) gene. Approximately 10 % of patients carry a nonsense mutation, which results in an inactive or unstable truncated protein. In some genetic disorders, including cystic fibrosis and Duchenne muscular dystrophy, restoration of full‐length protein has been achieved by aminoglycoside antibiotics, such as gentamicin and G‐418 (Geneticin). More recently, nonsense read‐through has been induced at greater rates using a non‐aminoglycoside drug, PTC124 (Ataluren), which has the advantage of being non‐toxic in contrast to the antibiotics. The efficacy of read‐through induced by three compounds, aminoglycosides G418 and gentamicin, and PTC124 were evaluated for four nonsense mutations of PAH in an in vitro expression system in two mammalian cell lines (COS‐7 and HEK293). The production of full‐length PAH was investigated using western blotting and the functionality confirmed by enzyme activity. Gentamicin and G‐418 induced read‐through of nonsense PAH mutations in HEK293 cells. The read‐through product partially restored enzymatic activity, which was significantly less than that of wild‐type, but comparable to a missense mutation of PAH associated with less severe forms of PKU. Treatment with PTC124 up to 100 μM did not result in full‐length PAH polypeptide. Nonsense read‐through drugs are a potential form of treatment for PKU, although the high dosage of aminoglycosides used is not appropriate in a clinical setting. In vitro studies with new non‐toxic read‐through agents as well as in vivo studies would also be essential to determine the extent of read‐through required to restore normal phenylalanine levels.
How Do Tougher Immigration Measures Affect Unauthorized Immigrants?
Authors: Amuedo-Dorantes Catalina , Puttitanun Thitima , Martinez-Donate Ana P.
Published: March 2013

The recent impetus of tougher immigration-related measures passed at the state level raises concerns about the impact of such measures on the migration experience, trajectory, and future plans of unauthorized immigrants. In a recent and unique survey of Mexican unauthorized immigrants interviewed upon their voluntary return or deportation to Mexico, almost a third reported experiencing difficulties in obtaining social or government services, finding legal assistance, or obtaining health care services. Additionally, half of these unauthorized immigrants reported fearing deportation. When we assess how the enactment of punitive measures against unauthorized immigrants, such as E-Verify mandates, has affected their migration experience, we find no evidence of a statistically significant association between these measures and the difficulties reported by unauthorized immigrants in accessing a variety of services. However, the enactment of these mandates infuses deportation fear, reduces interstate mobility among voluntary returnees during their last migration spell, and helps curb deportees’ intent to return to the United States in the near future.
Seized natural-history collections and the redefinition of scientific cosmopolitanism in the era of the French Revolution
Authors: LIPKOWITZ ELISE S.
Published: March 2013

In order to recast scholarly understanding of scientific cosmopolitanism during the French Revolution, this essay examines the stories of the natural-history collections of the Dutch Stadholder and the French naturalist Labillardière that were seized as war booty. The essay contextualizes French and British savants' responses to the seized collections within their respective understandings of the relationship between science and state and of the property rights associated with scientific collections, and definitions of war booty that antedated modern transnational legal conventions. The essay argues that the French and British savants' responses to seized natural-history collections demonstrate no universal approach to their treatment. Nonetheless, it contends that the French and British approaches to these collections reveal the emergence in the 1790s of new forms of scientific nationalism that purported to be cosmopolitan – French scientific universalism and British liberal scientific improvement.
Is quality of diet associated with the microvasculature? An analysis of diet quality and retinal vascular calibre in older adults
Authors: Gopinath Bamini , Flood Victoria M. , Wang Jie Jin , Rochtchina Elena , Wong Tien Y. , Mitchell Paul
Published: March 2013

It is unknown whether diet quality is associated with microvascular structure. The present study aimed to investigate the relationship between diet quality, reflecting adherence to dietary guidelines, with retinal microvascular calibre in older adults. The dietary data of 2720 Blue Mountains Eye Study participants, aged 50+ years, were collected using a semi-quantitative FFQ. A modified version of the Healthy Eating Index for Australians was developed to determine total diet scores (TDS). Fundus photographs were taken and retinal vascular calibre measured using computer-assisted techniques and summarised. After adjusting for age, sex, BMI, mean arterial blood pressure, smoking, serum glucose, leucocyte count and history of diagnosed stroke or CHD, persons with higher TDS had healthier retinal vessels cross-sectionally, with wider retinal arteriolar calibre (by approximately 3 μm, comparing the highest with the lowest quartile of TDS, Ptrend= 0·0001) and narrower retinal venular calibre (by approximately 2·5 μm; Ptrend= 0·02). In younger subjects aged ≤ 65 years, increasing TDS (lowest to the highest quartile) was associated with healthier retinal vessels: approximately 4·4 μm wider retinal arteriolar (Ptrend< 0·0001) and approximately 2·3 μm narrower venular calibre (Ptrend= 0·03). After multivariable adjustment, however, baseline TDS were not associated with retinal arteriolar (Ptrend= 0·89) or venular calibre (Ptrend= 0·25), 5 years later. Also, baseline TDS were not associated with the 5-year change in retinal arteriolar (β = 0·14; P= 0·29) or venular calibre (β = − 0·26; P= 0·07). Greater compliance with published dietary guidelines (higher diet quality) was cross-sectionally associated with wider retinal arterioles and narrower venules, indicating better retinal microvascular health.
The effect of the daily intake of inulin on fasting lipid, insulin and glucose concentrations in middle-aged men and women
Authors: Jackson Kim G. , Taylor Gary R. J. , Clohessy Anna M. , Williams Christine M.
Published: March 2013

The present study was carried out to examine the effect of the daily intake of 10 g inulin on fasting blood lipid, glucose and insulin levels in healthy middle-aged men and women with moderately raised total plasma cholesterol (TC) and triacylglycerol (TAG) levels. This study was a double-blind randomized placebo-controlled parallel study in which fifty-four middle-aged subjects received either inulin or placebo for a period of 8 weeks. Fasting blood samples were collected before the supplementation period (baseline samples 1 and 2, separated by 1 week) and at weeks 4 and 8, with a follow-up at week 12. Compared with baseline values, insulin concentrations were significantly lower at 4 weeks (P< 0·01) in the inulin group. There was a trend for TAG values, compared with baseline, to be lower in the inulin group at 8 weeks (P< 0·08) returning to baseline concentrations at week 12. On comparison of the inulin and placebo groups, the fasting TAG responses over the 8-week test period were shown to be significantly different (P< 0·05, repeated measures ANOVA), which was largely due to lower plasma TAG levels in the inulin group at week 8. The percentage change in TAG levels in the inulin group during the 8-week study was shown to correlate with the initial TAG level of the subjects (rs−0·499,P= 0·004). We therefore conclude that the daily addition of 10 g inulin to the diet significantly reduced fasting insulin concentrations during the 8-week test period and resulted in lower plasma TAG levels, particularly in subjects in whom fasting TAG levels were greater than 1·5 mmol/l. These data support findings from animal studies that fructans influence the formation and/or degradation of TAG-rich lipoprotein particles, and the insulin data are also consistent with recent studies showing attenuation of insulin levels in fructan-treated rats.
A new species ofMagelona(Polychaeta: Magelonidae) from Chinese coastal waters
Authors: Zhou Jin , Mortimer Kate
Published: March 2013

A description of a new species ofMagelona,M. parochilissp. nov. is presented, based on material collected from the Yellow Sea, China. The new species belongs to the ‘Magelona mirabilisgroup’ of magelonids, possessing a rounded prostomium, lacking prostomial horns and specialized chaetae on chaetiger 9. Paired anteriorly open pouches are present between chaetigers 11–12 and 14–15 (occasionally between chaetigers 17–18).Magelona parochilissp. nov. inhabits intertidal zones and shallow subtidal waters characterized by sandy mud.
Three species ofAsterocheres(Copepoda: Siphonostomatoida: Asterocheridae) from shallow Antarctic water
Authors: Kim Il-Hoi , Min Gi-Sik
Published: March 2013

Three species ofAsterocheres, including two new species, are reported as associates of sponges in shallow Antarctic water.Asterocheres spinosussp. nov. has a combination of diagnostic features: mandibular palp is one-segmented, caudal ramus is 1.88 times as long as wide, antennule is 20-segmented in the female and 18-segmented in the male, urosome is spinulose, and legs 1 and 2 display weak sexual dimorphsims. InA. raisp. nov., the body is large, 1.66 mm long in the female, the lateral margin of genital double-somite is smooth without setules or spinules, the exopod of antenna bears only a single seta, with two mucilaginous substances transformed from setae, and the third endopodal segment of leg 1 bears a prolonged distal process. A supplementary description is given forA. hirsutusBandera, Conradi and López-González, 2005, recorded previously from the Antarctic.
Martha Graham's Gilded Cage: Blood Memory—An Autobiography (1991)
Authors: Phillips Victoria
Published: March 2013

Although scholars, including myself, use Blood Memory to quote Martha Graham as evidence, other academics and dancers themselves have asserted that Graham did not write or construct the “autobiography.” The cross-reading of archives uncovers the narrative history of the making of Blood Memory, and how Graham, editors, and handlers constructed and reconstructed the book. In conclusion, by reading Graham's extensive oral histories and early writings, both scholars and dancers can recover the voice of the choreographer and woman.
Influences of farmer and veterinarian behaviour on emerging disease surveillance in England and Wales
Authors: GILBERT W. H. , HÄSLER B. N. , RUSHTON J.
Published: March 2013

Surveillance for new and re-emerging animal diseases in England and Wales is based on post-mortem and syndromic analysis of laboratory data collated in a central database by the Animal Health and Veterinary Laboratories Agency (AHVLA), with the aim of providing early warning of disease events prior to clinical diagnosis. Understanding the drivers for participation in such systems is critical to the success of attempts to improve surveillance sensitivity. The aim of this study was to investigate the decision-making process governing the submission of biological samples on which this surveillance system is based by use of questionnaires. Data extracted were used to structure and parameterize scenario trees modelling the probability of generating an entry in the surveillance database. The mean probability for database entry per case ranged from 0·085 for neurological disorders to 0·25 for enteric disease. These findings illustrate the importance of on-farm decision making to the generation of surveillance data.
The Fall and Rise of Doctors' Commons?
Authors: Barber Paul
Published: March 2013

The historic new LLM degree in Canon Law from the University of Wales College of Cardiff means that there now exists a body of Canon Law graduates, the first ‘home-grown’ canonists in this country since the King's Vicar-General. Thomas Cromwell, suppressed the faculties of Canon Law at Cambridge and Oxford in 1535. It was for a gathering of the first such graduates that the original version of this paper was prepared.
The Naturalised and the Surreal: changes in the perception of popular music sound
Authors: Brøvig-Hanssen Ragnhild , Danielsen Anne
Published: March 2013

In a musical context, the word ‘sound’ implies a set of sonic characteristics. Within popular music, this notion of sound sometimes supplies the very identity of a tune, a band or a musician. Sound is often conceptualised as a virtual space and in turn compared to actual spatial environments, such as a stage or an enclosed room. One possible consequence of this tendency is that this virtual space can become utterly surreal, displaying sonic features that could never occur in actual physical environments. This article concerns the ways in which the increased possibilities for creating a spatially surreal sound, thanks to new technological tools, have been explored within the field of popular music over the past few decades. We also look at the ways in which the effect of such features may have changed over time as a consequence of what we call processes of naturalisation. As a particularly interesting example of the complexity of such processes, we explore ‘the music sound stage’. In addition, we analyse three songs by Prince, Suede and Portishead to reveal the possibly surreal aspects of these productions.
Trends in the evolution of life, brains and intelligence
Authors: Rospars Jean-Pierre
Published: March 2013

ThefIterm of Drake's equation – the fraction of life-bearing planets on which ‘intelligent’ life evolved – has been the subject of much debate in the last few decades. Several leading evolutionary biologists have endorsed the thesis that the probability of intelligent life elsewhere in the universe is vanishingly small. A discussion of this thesis is proposed here that focuses on a key issue in the debate: the existence of evolutionary trends, often presented as trends towards higher complexity, and their possible significance. The present state of knowledge on trends is reviewed. Measurements of quantitative variables that describe important features of the evolution of living organisms – their hierarchical organization, size and biodiversity – and of brains – their overall size, the number and size of their components – in relation to their cognitive abilities, provide reliable evidence of the reality and generality of evolutionary trends. Properties of trends are inferred and frequent misinterpretations (including an excessive stress on mere ‘complexity’) that prevent the objective assessment of trends are considered. Finally, several arguments against the repeatability of evolution to intelligence are discussed. It is concluded that no compelling argument exists for an exceedingly small probabilityfI. More research is needed before this wide-ranging negative conclusion is accepted.
Organic agriculture in Iran: Farmers' barriers to and factors influencing adoption
Authors: Soltani Shohreh , Azadi Hossein , Mahmoudi Hossein , Witlox Frank
Published: March 2013

Organic agriculture is being promoted in Iran to address environmental problems resulting from the use of chemical materials in agriculture. Despite many advantages of organic agriculture, the results of several case studies show that its adoption rate is still very low among farmers. The purpose of this paper is to review previous studies that investigated the main factors influencing and challenging the adoption of organic agriculture. The review included journal articles and conference papers from 2007 to 2012. The results show that Iranian farmers have strong motives for the adoption, yet face challenges in certifying, marketing, and accessing reliable technical information and credits. Given the review of factors that govern farmers' adoption of organic agriculture, key mechanisms for promoting farmers' adoption are discussed. Further research is needed to learn how to bring these mechanisms into play in Iran.
Brain anatomy of autism spectrum disorders I. Focus on corpus callosum
Authors: Bellani M. , Calderoni S. , Muratori F. , Brambilla P.
Published: March 2013

This brief review aims to examine the structural magnetic resonance imaging (sMRI) studies on corpus callosum in autism spectrum disorders (ASD) and discuss the clinical and demographic factors involved in the interpretation of results.
Synthesis of well-defined PPV containing block polymers with precise endgroup control by a dual-initiator strategy
Authors: Cosemans Inge , Vandenbergh Joke , Lutsen Laurence , Vanderzande Dirk , Junkers Tanja
Published: March 2013

The initiator efficiency in PPV polymerization was tested and PPV-b-(P-tBuA) block copolymers were synthesized. Via hydrolysis amphiphilic materials undergoing micelle formation were obtained.
Neuromodulatory role of angiotensin-(1–7) in the central nervous system
Authors: Gironacci Mariela M. , Carbajosa Nadia A. Longo , Goldstein Jorge , Cerrato Bruno D.
Published: March 2013

Ang-(1–7) [angiotensin-(1–7)] constitutes an important functional end-product of the RAS (renin–angiotensin system) endogenously formed from AngI (angiotensin I) or AngII (angiotensin II) through the catalytic activity of ACE2 (angiotensin-converting enzyme 2), prolyl carboxypeptidase, neutral endopeptidase or other endopeptidases. Ang-(1–7) lacks the pressor, dipsogenic or stimulatory effect on aldosterone release characteristic of AngII. In contrast, it produces vasodilation, natriuresis and diuresis, and inhibits angiogenesis and cell growth. At the central level, Ang-(1–7) acts at sites involved in the control of cardiovascular function, thus contributing to blood pressure regulation. This action may result from its inhibitory neuromodulatory action on NE [noradrenaline (norepinephrine)] levels at the synaptic cleft, i.e. Ang-(1–7) reduces NE release and synthesis, whereas it causes an increase in NE transporter expression, contributing in this way to central NE neuromodulation. Thus, by selective neurotransmitter release, Ang-(1–7) may contribute to the overall central cardiovascular effects. In the present review, we summarize the central effects of Ang-(1–7) and the mechanism by which the peptide modulates NE levels in the synaptic cleft. We also provide new evidences of its cerebroprotective role.
Étude des relations entre la morphologie cranio-faciale et l’occlusion en denture temporaire : remodelages occipitaux et singularités basicrâniennes déterminantes pour l’occlusion
Authors: Deshayes Marie-Josèphe , Deshayes Julie
Published: March 2013

Avant toute action ou interception précoce, chez un enfant en denture temporaire, il nous paraît indispensable d’analyser de plus près certains éléments structuraux de la base crânienne de l’enfant. Pour formaliser les indications majeures d’une réelle prise en charge orthopédique, ou seulement intercepter les dysfonctions avec des appareils fonctionnels plus simples, il faut donc au préalable pouvoir classer la dysharmonie de l’enfant, squelettique et/ou dysfonctionnelle. Pour faire face à ces contraintes diagnostiques, un groupe de 243 enfants en denture temporaire a été examiné. Notre expertise clinique a permis de sélectionner des mesures céphalométriques supposées en lien avec le type de dysharmonie squelettique (à partir de repères osseux crâniens et faciaux localisés sur les téléradiographies numériques de profil). La classification occlusale a pris en compte des critères occlusaux et observé la fonction masticatoire. Les résultats statistiques (méthode experte de variables céphalométriques) montrent qu’en denture temporaire certaines architectures crâniennes privilégient un certain équilibre occlusal. Nous voyons que l’amplitude de flexion basicrânienne (ou l’angle sphénoïdal) est sous l’influence du remodelage de l’occipital : le processus de flexion ontogénique de la base et l’amplitude de fermeture de l’angle sphénoïdal dépendent essentiellement du remodelage de l’os occipital selon trois modes principaux. Des corrélations sont visibles entre ces groupes et la morphologie faciale, l’avancée ou le recul du menton. La déduction clinique importante est que la fonction masticatoire en denture temporaire s’organise selon les contraintes architecturales issues du remodelage basicrânien; l’impact des dysfonctions serait certes tributaire de la dysfonction elle-même mais aussi des singularités architecturales de la base crânienne.
Hyperfine coupling of the hydrogen atom in high temperature water
Authors: Nuzhdin Kirill , Bartels David M.
Published: March 2013

The hyperfine coupling constant of the hydrogen atom has been measured in pressurized liquid water up to 300 °C. The reduced constant Awater/Avacuum is 0.9939 at room temperature, and decreases to a minimum of 0.9918 at 240 °C. The reduced constant then increases at higher temperature. The g-factor is 2.002244(10) at room temperature and decreases to 2.00221(1) at 240 °C. The change in g-factor is proportional to the change in hyperfine coupling. The behavior below 110 °C is in excellent agreement with a previously proposed model in which the H atom is confined to a harmonic solvent cage, and vibrations within the cage mix “p-type” character into the wavefunction, resulting in Awater/Avacuum < 1. The harmonic model breaks down above 130 °C. We demonstrate that a classical binary collision model using approximate partial molar volume information can recover the observed minima near 240 °C.
Towards an invariant geometry of double field theory
Authors: Hohm Olaf , Zwiebach Barton
Published: March 2013

We introduce a geometrical framework for double field theory in which generalized Riemann and torsion tensors are defined without reference to a particular basis. This invariant geometry provides a unifying framework for the frame-like and metric-like formulations developed before. We discuss the relation to generalized geometry and give an “index-free” proof of the algebraic Bianchi identity. Finally, we analyze to what extent the generalized Riemann tensor encodes the curvatures of Riemannian geometry. We show that it contains the conventional Ricci tensor and scalar curvature but not the full Riemann tensor, suggesting the possibility of a further extension of this framework.
Perspective: The glass transition
Authors: Biroli Giulio , Garrahan Juan P.
Published: March 2013

We provide here a brief perspective on the glass transition field. It is an assessment, written from the point of view of theory, of where the field is and where it seems to be heading. We first give an overview of the main phenomenological characteristics, or “stylised facts,” of the glass transition problem, i.e., the central observations that a theory of the physics of glass formation should aim to explain in a unified manner. We describe recent developments, with a particular focus on real space properties, including dynamical heterogeneity and facilitation, the search for underlying spatial or structural correlations, and the relation between the thermal glass transition and athermal jamming. We then discuss briefly how competing theories of the glass transition have adapted and evolved to account for such real space issues. We consider in detail two conceptual and methodological approaches put forward recently, that aim to access the fundamental critical phenomenon underlying the glass transition, be it thermodynamic or dynamic in origin, by means of biasing of ensembles, of configurations in the thermodynamic case, or of trajectories in the dynamic case. We end with a short outlook.
Modelling of infrared optical constants for polycrystalline low pressure chemical vapour deposition ZnO:B films
Authors: Prunici P. , Hamelmann F. U. , Beyer W. , Kurz H. , Stiebig H.
Published: March 2013

Doped zinc oxide films are of high interest in thin film solar cell technology for application as transparent conducting oxide. Rapid and detailed characterisation of ZnO thin film properties is required for quality control and optimisation of the deposited films. In the present work, a new model of dielectric functions based on the effective medium approximation (EMA) is developed and is applied for characterisation of polycrystalline boron doped zinc oxide (ZnO:B) films, deposited by low pressure chemical vapour deposition (LPCVD) technique onto glass substrates. The model takes into account that polycrystalline ZnO is considered to consist of crystal grains surrounded by depletion layers. Using this model and Fourier Transform Infrared Spectroscopy (FTIR) performed in reflection configuration over a wide mid-infrared spectral region (from 2 μm up to 25 μm), the properties of depletion layer and the bulk of the grains in ZnO can be rapidly characterised in detail, and the volume fraction of the depletion layer can be extracted. The results are in good agreement with previously presented theories of electron transport in polycrystalline materials. Using electrical measurements like conductivity and Hall techniques in addition to the optically determined parameters, predominant electron scattering mechanisms in polycrystalline films for different doping levels are identified. The measurements show the impact of the doping level on depletion layer of the crystallites. It is shown, furthermore, that under a water vapour rich environment the volume fraction of the depletion layer may increase up to 5 times and more, while the mobility of the charge carriers in the depletion layer drops drastically from about 31 cm2V−1s−1 to about 8 cm2V−1s−1. This indicates that water vapour exposure causes an increase of the potential barrier in the grain boundary depletion layer, limiting the electron transport across the grain boundaries to a classical thermionic emission mechanism.
Reshaping and capturing Leidenfrost drops with a magnet
Authors: Piroird Keyvan , Texier Baptiste Darbois , Clanet Christophe , Quéré David
Published: March 2013

Liquid oxygen, which is paramagnetic, also undergoes Leidenfrost effect at room temperature. In this article, we first study the deformation of oxygen drops in a magnetic field and show that it can be described via an effective capillary length, which includes the magnetic force. In a second part, we describe how these ultra-mobile drops passing above a magnet significantly slow down and can even be trapped. The critical velocity below which a drop is captured is determined from the deformation induced by the field.
Optimization of viscosity and thixotropy for organic medium to achieve high photovoltaic conversion efficiency of silicon solar cells
Authors: Zhang Jielan , Cui Yanbin , Wang Hui
Published: March 2013

The properties of the silver paste have great influence on the photovoltaic conversion efficiency (Eff) of monocrystalline silicon (Si) solar cells. The organic medium is a very important part of silver paste. In this paper, two main performance parameters of organic medium (viscosity and thixotropic index) are systematically studied. When the thixotropic index of the organic medium is more than 5.50 and the viscosity is between 15 pa·s and 30 pa·s, the silver paste has good thixotropy and appropriate printability. The experimental results indicate that organic medium has appropriate viscosity (20 pa·s) and the highest thixotropic index (9.35) when its composition is as follows: solvents 80.00 wt. %, thickener 3.00 wt. %, thixotropic agents 8.00 wt. %, surfactant 3.00 wt. %, and coupling agent 6.00 wt. %. The silver paste shows appropriate viscosity (270–370 pa·s), high thixotropic index (6.50), and good printability when the percentage of organic medium is about 12.00 wt. %. Using this silver paste, the front electrode grid of Si solar cells has high ratio of height to width as well as fine edge definition. Meanwhile, the Eff of monocrystalline Si solar cells reach 18.29%.
Ionization of large homogeneous and heterogeneous clusters generated in acetylene–Ar expansions: Cluster ion polymerization
Authors: Kočišek J. , Lengyel J. , Fárník M.
Published: March 2013

Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of ≈8%, while mixed species are produced at low concentrations (≈0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression $({\rm C}_2{\rm H}_2)_n^+$(C2H2)n+. At the electron energies ⩾21.5 eV above the CH+CH+ dissociative ionization limit of acetylene the fragment ions nominally labelled as (C2H2)nCH+, n ⩾ 2, are observed. For n ⩽ 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C2H2)n − k × H]+ and [(C2H2)nCH − k × H]+. The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The \documentclass[12pt]{minimal}\begin{document}${\rm C}_{3} {\rm H}_3^+$\end{document}C3H3+ ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of ≈13.7 eV indicates that a less rigid covalently bound structure of \documentclass[12pt]{minimal}\begin{document}${\rm C}_{6} {\rm H}_6^+$\end{document}C6H6+ ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Arn(C2H2)+ fragments above ≈15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of \documentclass[12pt]{minimal}\begin{document}${\rm Ar}_{n \ge 2}({\rm C}_{2} {\rm H}_{2})_{m\ge 2}^+$\end{document} Ar n≥2(C2H2)m≥2+ at ≈13.7 eV is discussed in terms of an exciton transfer mechanism.
In situ broadband cryogenic calibration for two-port superconducting microwave resonators
Authors: Yeh Jen-Hao , Anlage Steven M.
Published: March 2013

We introduce an improved microwave calibration method for use in a cryogenic environment, based on a traditional three-standard calibration, the Thru-Reflect-Line (TRL) calibration. The modified calibration method takes advantage of additional information from multiple measurements of an ensemble of realizations of a superconducting resonator, as a new pseudo-Open standard, to correct errors in the TRL calibration. We also demonstrate an experimental realization of this in situ broadband cryogenic calibration system utilizing cryogenic switches. All calibration measurements are done in the same thermal cycle as the measurement of the resonator (requiring only an additional 20 min), thus avoiding 4 additional thermal cycles for traditional TRL calibration (which would require an additional 12 days). The experimental measurements on a wave-chaotic microwave billiard verify that the new method significantly improves the measured scattering matrix of a high-quality-factor superconducting resonator.
Optimization of absorber layers' thickness in a Si micromorph solar cell for current matching with intermediate ZnO reflector
Authors: Bohra S. S. , Panchal A. K.
Published: March 2013

In a micromorph silicon (Si) solar cell, the optimum performance is decided by the top hydrogenated amorphous Si (a-Si:H) and the bottom microcrystalline Si (μc-Si) absorber layer thicknesses. This paper investigates the performance of the micromorph cell using modeling and simulation studies in matlab. The short circuit current density (Jsc), open circuit voltage (Voc), fill factor, and efficiency (η) of the cells are analysed by varying thicknesses of the top a-Si:H and the bottom μc-Si absorber layers with and wihtout ZnO Intermidiate Reflector (ZIR). ZIR improves current density of top a-Si:H i-layer and hence thickness reduction of top subcell i-layer. Due to this, the light induced degradation can be minimised. For each top a-Si:H layer thickness, the bottom μc-Si layer thickness is varied in steps. The micromorph structure is numerically solved using Newton-Raphson technique and current density-voltage characteristics for top a-Si:H, bottom μc-Si:H sub-cells, and composite cell are obtained. One of the combinations with the top a-Si:H layer with thickness of 300 nm and the bottom μc-Si layer with thickness of 3.25 μm gives the best efficiency of 13.12% with ZIR. The simulation study performed here can be extended to design third generation multijunction Si quantum dots solar cells.
Stimulated emission related anomalous change of electrical parameters at threshold in GaN-based laser diodes
Authors: Li Ding , Yang Wei , Feng Liefeng , Roth Peter W. , He Juan , Du Weimin , Yang Zhijian , Wang Cunda , Zhang Guoyi , Hu Xiaodong
Published: March 2013

We report the stimulated emission related anomalous behavior of electrical parameters in GaN-based laser diodes based on both experiments and self-consistent calculations. In particular, the separation of quasi-Fermi levels of electrons and holes across active region shows a drop (or “pinning”) in threshold region, followed by an increase with current. The start and end points correspond to the two kink points of the first derivative of the optical output power-current (P-I) curve. This abnormal change of electrical parameters always satisfies the need of sufficient carriers for stimulated emission in the process of transition to lasing as well as lasing enhancement.
Nanomechanical method to gauge emission quantum yield applied to nitrogen-vacancy centers in nanodiamond
Authors: Frimmer Martin , Mohtashami Abbas , Femius Koenderink A.
Published: March 2013

We present a technique to nanomechanically vary the distance between a fluorescent source and a mirror, thereby varying the local density of optical states at the source position. Our method can, therefore, serve to measure the quantum efficiency of fluorophores. Application of our technique to nitrogen-vacancy defects in diamond nanocrystals shows that their quantum yield can significantly differ from unity. Relying on a lateral scanning mechanism with shear-force probe-sample distance control our technique is straightforwardly implemented in most state-of-the-art near-field microscopes.
Low-noise single-layer YBa2Cu3O7-x dc superconducting quantum interference devices magnetometers based on step-edge junctions
Authors: Lam S. K. H. , Cantor R. , Lazar J. , Leslie K. E. , Du J. , Keenan S. T. , Foley C. P.
Published: March 2013

We report the performance of twenty-four high temperature superconducting dc superconducting quantum interference devices (SQUIDs) whose Josephson junctions were formed from a YBa2Cu3O7-x (YBCO) grain boundary on an engineered MgO step-edge substrate. Each device has the same SQUID design with an inductance of 65 pH, and consisted of two SQUIDs with different junction widths, connected in series, and directly coupled to a large pick-up loop of 7.5 mm × 8.8 mm on a 1 × 1 cm2 chip. 58% of the devices had a peak-to-peak modulation voltage, ΔV, larger than 30 μV. The typical values of the white flux and field noise were 4.7 μΦo and 56 fT/Hz, respectively, in a magnetically shielded environment with 1/f corner frequency at 15–20 Hz. In an unshielded environment, there was no degradation of white noise.
Heat transfer enhancement in solar air heater with V-shaped perforated baffles
Authors: Chamoli Sunil , Thakur N. S.
Published: March 2013

This experimental study, investigates the heat transfer and friction characteristics in a rectangular duct having its one broad wall heated and roughened with periodic V-down shaped perforated baffles. This work covered a range of Reynolds number (Re) 3800–19 000, open area ratio (β) 12%–44%, relative hole position (l/e) 0.429–0.571 for the fixed values of relative baffle height (e/H) 0.4, relative roughness pitch (p/e) 5, and angle of attack of 60°. The effects of relative hole position on Nusselt number and friction factor have been discussed and results compared under similar flow and boundary conditions to investigate the enhancement in Nusselt number and friction factor. The maximum enhancement in Nusselt number and friction factor has been obtained at an open area ratio of 12% and is of the order of 2.2 and 5.2 times of that of smooth duct, respectively. Thermohydraulic performance of solar air heater has been found to be substantially improved by the application such perforated baffles.
Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing
Authors: Fujii Mami , Ishikawa Yasuaki , Ishihara Ryoichi , van der Cingel Johan , Mofrad Mohammad R. T. , Horita Masahiro , Uraoka Yukiharu
Published: March 2013

In this study, we successfully achieved a relatively high field-effect mobility of 37.7 cm2/Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50 °C according to thermal calculation. Our analysis revealed that high-energy irradiation in ELA produced a mixed phase of InZnO and SiO2, leading to the deterioration of TFT characteristics.
Filament observation in metal-oxide resistive switching devices
Authors: Celano Umberto , Yin Chen Yang , Wouters Dirk J. , Groeseneken Guido , Jurczak Malgorzata , Vandervorst Wilfried
Published: March 2013

Metal-oxide-based resistive random access memory (RRAM) is a predominant candidate for future non-volatile memories. In this Letter, we report on an innovative technique to observe conductive filaments in these oxide-based RRAM devices. We demonstrate the role of these conductive filaments as responsible for the different ON/OFF resistive states in memory devices by means of Conductive Atomic Force Microscopy (C-AFM). More specifically, C-AFM is used to cycle, de-process, and finally characterizes capacitor-like devices. Different conductive filaments are found for the different memory states. As we show, the ON/OFF state of the devices is associated to changes in morphological and electrical properties of the conductive filaments.
The role of Ag nanoparticles in inverted polymer solar cells: Surface plasmon resonance and backscattering centers
Authors: Xu Peng , Shen Liang , Meng Fanxu , Zhang Jiaqi , Xie Wenfa , Yu Wenjuan , Guo Wenbin , Jia Xu , Ruan Shengping
Published: March 2013

Here, we demonstrate silver (Ag) nanoparticles (NPs) existing in molybdenum trioxide (MoO3) buffer layers can improve the photocurrent by surface plasmon resonance (SPR) and backscattering enhancement. The device structure is glass/indium tin oxides/titanium dioxide (TiO2)/regioregular poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester/MoO3/Ag NPs/MoO3/Ag. Compared to the device without Ag NPs, the short current density (Jsc) is improved from 7.76 ± 0.14 mA/cm2 to 8.89 ± 0.12 mA/cm2, and the power conversion efficiency is also enhanced from 2.70% ± 0.11% to 3.35% ± 0.08%. The transmittance spectra show that the device with Ag NPs has weaker transmittance than the device without, which could be attributed to the photons absorption of Ag NPs and light scattering by Ag NPs. The absorption profile of the devices with or without Ag NPs is simulated using finite-difference time-domain methods. It is approved that the Ag NPs result in the absorption improvement by SPR and backscattering enhancement.