bluuebunny/crossref_metadata_2025 huggingface dataset:
Prüfung vorgespannter, gebogener Gläser
Authors: Weller Bernhard , Krampe Philipp , Engelmann Michael
Published: May 2012

Seitens der Ermittlung von Materialkennwerten warm gebogener Gläser sind noch keine einheitlichen Normgrundlagen vorhanden. In dieser Veröffentlichung werden daher Erfahrungen zur Prüfung gebogener Gläser analysiert, um den verfügbaren Wissensstand zusammenzufassen. Im Fokus stehen dabei die Biegezugfestigkeit in Anlehnung an DIN EN 1288 Teil 3, die Bestimmung der Vorspannung mit spannungsoptischen Verfahren und Bruchbilduntersuchungen. Dabei werden die vorhandenen prüftechnischen Grenzen beschrieben.
Innovative Stahlfensterkonstruktionen für das Weltkulturerbe Bauhaus Dessau
Authors: Brenne Winfried , Nickmann Ulrich , Mathijssen Mark , Weller Bernhard , Reich Stefan
Published: May 2012

Das Bauhaus in Dessau, als Inbegriff der modernen Architektur, ist geprägt durch klare Fassadenstrukturen, großflächige Verglasungen mit filigranen Profilstrukturen, bis hin zu Fassadenbereichen, die gänzlich durch transparente Vorhangfassaden aufgelöst sind. Das Bauhausgebäude, in den Jahren 1925‐26 nach Intentionen von Walter Gropius errichtet, gehört zum Weltkulturerbe. Bei der energetischen Sanierung und dem Austausch von Verglasungen wurden daher höchste Anforderungen an Materialität und Proportionen gestellt, im Besonderen an die Feinheit von Fensterprofilen. Die Verwendung der thermisch getrennten, stählernen Fensterprofile ist das Resultat einer langjährigen Entwicklungsarbeit und erforderte eine baurechtliche Betrachtung und Genehmigung.
Your Rainbow Panorama – Ein begehbarer Regenbogen aus Stahl und Glas
Authors: Kahlert Wolfgang , Spangemacher Frank
Published: May 2012

Das Dach des AroS Aarhus Kunstmuseum, Dänemark krönt seit Ende Mai 2011 in 40 m Höhe ein begehbarer Regenbogen mit einem Durchmesser von 52 m. Getragen von zwölf filigranen Stahlstützen, die sich gegen den Himmel kaum abzeichnen. Der begehbare Raum des Regenbogens wird gebildet von einer hybriden Glas‐Stahl‐Tragkonstruktion ausgebildet als Zylinderring. Die Verglasungen tragen dabei nicht nur das Dach, sondern steifen auch die Stahlbodenkonstruktion aus. Neben Knickbeanspruchungen wurden insbesondere auch verschiedene Ausfallszenarien für die Hybridkonstruktion untersucht. Die Farbigkeit erhält die Verglasung durch den Einsatz von bis zu sechs farbigen PVB‐Folien, die das Spektrum des Regenbogens durch 42 verschiedene Farbtöne abbilden.
Punktförmig gelagerte Verglasung nach E DIN 18008 Teil 3
Authors: Weller Bernhard , Reich Stefan , Engelmann Michael
Published: May 2012

Die zum jetzigen Zeitpunkt in der Entwurfsfassung vorliegende, neue Glasbaubemessungsnorm E DIN 18008 Teil 3 erlaubt den rechnerischen Nachweis punktförmig gelagerter Verglasungen. Anhand eines gläsernen Eingangsbereiches werden die Berechnungsverfahren der neuen Norm vorgestellt. Diese umfassen sowohl analytische als auch numerische Verfahren. Im Beitrag erfährt dabei die numerische Abbildung und Modellverifizierung mit Hilfe universeller Baustatik‐Software eine besondere Beachtung. Die in den allgemeinen bauaufsichtlichen Zulassungen der Punkthalterhersteller und der E DIN 180083 angegebenen Verifizierungsabläufe gewährleisten die Erstellung von realitätsnahen, numerischen Modellen punktförmig gelagerter Verglasungen.
Diseases of the tooth: the genetic and molecular basis of inherited anomalies affecting the dentition
Authors: Cobourne Martyn T. , Sharpe Paul T.
Published: May 2012

In humans, inherited variation in the number, size, and shape of teeth within the dentitions are relatively common, while rarer defects of hard tissue formation, including amelogenesis and dentinogenesis imperfecta, and problems associated with tooth eruption are also seen. In many cases, these anomalies occur in isolation, but they can also present as a feature of numerous well‐characterized developmental syndromes. Complex reiterative signaling between the epithelium and mesenchyme is a feature of normal tooth development in the embryo, occurring from early patterning through morphogenesis, hard tissue formation and during root development. Significant events also occur during postnatal development of the dentition, including hard tissue maturation and tooth eruption. In the last decade, advances in human and mouse genetics have meant that in many cases candidate genes have been identified for these anomalies. These genes have provided a useful platform for developmental biologists, allowing them to begin elucidating how these signals interact to generate a functional dentition and understand the mechanisms underlying many of the anomalies that are seen in human populations. In this article, we review current concepts relating to the developmental biology of tooth number, size, and shape, formation of the dental hard tissues and eruption of the tooth into the oral cavity. We will focus on the molecular mechanisms underlying these processes in both health and disease. WIREs Dev Biol 2013, 2:183–212. doi: 10.1002/wdev.66

This article is categorized under:

Birth Defects > Craniofacial and Nervous System Anomalies
Effects of soil physicochemical properties and stand age on fine root biomass and vertical distribution of plantation forests in the Loess Plateau of China
Authors: Chang Ruiying , Fu Bojie , Liu Guohua , Yao Xueling , Wang Shuai
Published: May 2012

The responses of aboveground parts of the forest to changes in environmental factors and stand age is well studied, but the same is not true for the belowground parts of the forest. Two plantation black locust (Robinia pseudoacacia L.) forest sites were taken in the Loess Plateau of China, one in the drier, infertile, more sandy area of the middle Loess Plateau, and another in the wetter, fertile, more clay‐filled area of the southern Loess Plateau. At each site, both a younger (8‐year‐old) plantation stand and an older (30‐year‐old) plantation stand were included to study the effects of soil physicochemical properties and stand age on the fine root (<2 mm) biomass and vertical distribution of black locust forests. Root samples were taken with soil cores to a depth of 100 cm. The fine root biomass decreased from the middle site to the southern site for both stand ages, as expected, and the decrease could be due to a higher fine root N concentration associated with a higher fine root turnover rate at the southern site. There was a similar rooting pattern, though not deeper, in the drier, sandy site as predicted based on soil water infiltration and evaporation demands. The different effects of stand characters (e.g., tree density, tree height) on the fine root distribution as compared with the environmental properties may contribute partly to the similar pattern found in the two sites. The fine root biomass increased with stand age in both sites. In contrast to the evident difference in fine root biomass, there was no clear trend in the fine root vertical distribution pattern with stand age. Our results indicate that fine roots are likely to respond to changes in soil physicochemical properties and stand age by changing fine root biomass rather than by varying rooting pattern.
Reliability of plain radiographic parameters for developmental dysplasia of the hip in children
Authors: Upasani Vidyadhar V. , Bomar James D. , Parikh Gaurav , Hosalkar Harish
Published: May 2012

Introduction

Few studies have evaluated the reliability and reproducibility of the femoral neck-shaft angle (NSA), center-edge angle (CEA), and acetabular index (AI) in young children with developmental dysplasia of the hip (DDH). We wanted to determine whether these parameters could be used reliably by practitioners.

Methods

Fifty radiographs from 21 children with DDH were reviewed. Analysis was performed by three observers, at two time periods. The intra- and inter-observer reliability for each measure was assessed.

Results

At time period one, we noted a “high” level of agreement between observers when measuring the NSA, a “low” level when measuring the CEA, and a “moderate” level when measuring the AI. At time period two, we noted a “very high” level of agreement between observers when measuring the NSA and a “high” level when measuring the CEA and AI. When comparing the measurements of observer 1 at the two different time periods, we noted nearly “very high” agreement when measuring the NSA, a “moderate” agreement when measuring the CEA, and a “high” agreement for the AI. In comparing the measurements of observer 2, we noted “very high” agreement for the NSA and “high” agreement for the CEA and AI. In comparing the measurements for observer 3, we noted nearly “very high” agreement for the NSA, nearly “high” agreement for the CEA, and “high” agreement for the AI.

Conclusion

It is difficult to reliably measure three-dimensional pelvic morphology on a frontal plane radiograph, especially when important pelvic landmarks have yet to ossify.
Religiosity and Fear of Death: A Theory-Oriented Review of the Empirical Literature
Authors: Ellis Lee , Wahab Eshah A.
Published: May 2012

Do religious people fear death more or less than those who are nonreligious? According to two theories, religiosity and fear of death should be inversely correlated. A third theory suggests that moderately religious persons should be more fearful than those who are extremely religious or nonreligious. Yet a fourth theory predicts that religiosity and fear of death should be positively correlated. Eighty-four studies were located in which pertinent findings have been presented, several of which reached more than one conclusion based on different definitions of religiosity. Overall, 40 studies provided findings supporting the conclusion that religiosity and fear of death are inversely correlated, nine supported a curvilinear relationship, 27 supported a positive correlation, and 32 indicated that no significant relationship exists between religiosity and fear of death. Chi square analyses of several features of these conflicting studies suggest that there is probably a modest negative correlation between religiosity and fear of death among persons who are at least modestly religious. However, when nonreligious individuals are sampled alongside those who are both moderately and extremely religious, the overall relationship shifts to being curvilinear, and possibly even positive, depending on the aspect of religiosity being assessed. The implications of these conclusions for the four theories are discussed.
Clinical Issues—June 2012
Authors: Van Wicklin Sharon A.
Published: May 2012

This Month

Using prepared endotracheal tubes

Key words: endotracheal tubes, ETTs, prepared endotracheal tubes.

Surgical hand antisepsis using plain soap

Key words: plain soap, antimicrobial soap, surgical hand antisepsis, surgical hand scrub.

Working with an impaired team member

Key words: impaired health care provider, substance abuse, patient advocate.

Using warmed irrigation fluids during arthroscopy procedures

Key words: irrigation fluid, warmed fluids, arthroscopy, burns.
Different patterns of Robertsonian fusion pairing in Bovidae and the house mouse: the relationship between chromosome size and nuclear territories
Authors: WESCHE PHILIPP L. , ROBINSON TERENCE J.
Published: May 2012

Using a dataset of karyotypic changes reported for bovids and the house mouse (Mus musculus domesticus) together with information from the cattle (Bos taurus) and mouse genomes, we examined two principal variables that have been proposed to predict chromosomal positioning in the nucleus, chromosome size and GC content. These were expected to influence the distribution of Robertsonian (Rb) fusions, the predominant mode of chromosomal change in both taxa. We found the largest chromosomes to be most frequently involved in fusions in bovids, and confirm earlier reports that chromosomes of intermediate size were the most frequent fusers in mice. We then tested whether chromosomal positioning can explain Rb fusion frequencies. We classified chromosomes into groups by size and considered the frequency of interactions between specific groups. Among the interactions, mouse chromosomes showed a slight tendency to fuse with neighbouring chromosomes, in line with expectations of chromosomal positioning, but also resembling predictions from meiotic spindle-induced bias. Bovids, on the other hand, showed no trend in interactions, with small chromosomes being the least frequent partner for all size classes. We discuss the results in terms of nuclear organization at various cell cycle stages and the proposed mechanisms of Rb fusion formation, and note that the difference can be explained by (i) considering bovid species generally to be characterized by a greater intermingling of chromosomal size classes than the house mouse, or (ii) by the vastly different timescales underpinning their evolutionary histories.
Potential roles of stem cells in the management of sensorineural hearing loss
Authors: Ibekwe T S , Ramma L , Chindo B A
Published: May 2012

Background:

In the management of sensorineural hearing loss, effective therapy for degenerated hair cells, third order neurons, ganglions, dendrites and synaptic areas of the vestibulo-cochleo-cerebral pathway remains an enigma. Transplantation of stem and progenitor cells appears to be an emerging potential solution, and is the focus of this review.

Aim:

To review recent developments in the management of sensorineural hearing loss in the field of stem cell research.

Materials and method:

A systematic review of the English language literature included all experimental and non-experimental studies with a Jadad score of three or more, published between 2000 and 2010 and included in the following databases: Cochrane Library Ear, Nose and Throat Disorders; Medline; Google Scholar; Hinari; and the Online Library of Toronto University.

Results:

Of the 455 and 29 600 articles identified from Medline and Google Scholar, respectively, 48 met the inclusion criteria. These were independently reviewed and jointly analysed.

Conclusion:

Although there is not yet any evidence from successful human studies, stem cell and ‘alternative stem cell’ technology seems to represent the future of sensorineural hearing loss management.
The Role of Photography in the Protection, Identification, and Recovery of Cultural Heritage
Authors: Mattern Eleanor
Published: May 2012

This article seeks to contribute to the study surrounding documentation and the illicit trade in cultural property by examining the uses of photography by the international community. Popular and academic literature, news reports, and online databases reveal three primary and interconnected relationships that exist between photography and the trade of cultural heritage. This article presents photography as, first, an aid for the protection and identification of cultural heritage and, second, as a form of evidence to support an ownership claim by a country calling for repatriation.
Investigation of prevalence and risk factors forCampylobacterin broiler flocks at slaughter: results from a UK survey
Authors: LAWES J. R. , VIDAL A. , CLIFTON-HADLEY F. A. , SAYERS R. , RODGERS J. , SNOW L. , EVANS S. J. , POWELL L. F.
Published: May 2012

During 2007–2009 a UK-wide, 3-year stratified randomized survey of UK chicken broiler flocks was conducted to estimate the prevalence ofCampylobacter-infected batches of birds at slaughter. Thirty-seven abattoirs, processing 88·3% of the total UK slaughter throughput, were recruited at the beginning of the survey. Of the 1174 slaughter batches sampled, 79·2% were found to be colonized withCampylobacter, the majority of isolates beingC. jejuni. Previous partial depopulation of the flock [odds ratio (OR) 5·21], slaughter in the summer months (categorized as June, July and August; OR 14·27) or autumn months (categorized as September, October and November; OR 1·70) increasing bird age (40–41 days, OR 3·18; 42–45 days, OR 3·56; ⩾46 days, OR 13·43) and higher recent mortality level in the flock (1·00–1·49% mortality, OR 1·57; ⩾1·49% mortality, OR 2·74) were all identified as significant risk factors forCampylobactercolonization of the birds at slaughter. Time in transit to the slaughterhouse of more than 2·5 h was identified as a protective factor (OR 0·52).
Excess body fat in obese and normal-weight subjects
Authors: Thomas E. Louise , Frost Gary , Taylor-Robinson Simon D. , Bell Jimmy D.
Published: May 2012

Excess body adiposity, especially abdominal obesity and ectopic fat accumulation, are key risk factors in the development of a number of chronic diseases. The advent ofin vivoimaging methodologies that allow direct assessment of total body fat and its distribution have been pivotal in this process. They have helped to identify a number of sub-phenotypes in the general population whose metabolic risk factors are not commensurate with their BMI. At least two such sub-phenotypes have been identified: subjects with normal BMI, but excess intra-abdominal (visceral) fat (with or without increased ectopic fat) and subjects with elevated BMI (> 25 kg/m2) but low visceral and ectopic fat. The former sub-phenotype is associated with adverse metabolic profiles, while the latter is associated with a metabolically normal phenotype, despite a high BMI. Here, examples of these phenotypes are presented and the value of carrying out enhanced phenotypical characterisation of subjects in interventional studies discussed.
MULTIPLE TESTING FOR OUTPUT CONVERGENCE
Authors: Deckers Thomas , Hanck Christoph
Published: May 2012

This paper tests for output convergence acrossn= 51 economies, employing the definition of Pesaran [Journal of Econometrics138, 312–355 (2007)]. The definition requires output gaps to be stationary around a constant mean. But when alln(n− 1)/2 pairs of log per capita output gaps are considered, this results in more than 1,000 unit root tests to be conducted. Hence, because of the ensuing multiplicity of the testing problem, a nontrivial number of output gaps will be falsely declared to be stationary when each of then(n− 1)/2 hypotheses is tested at some conventional level like 5%. To solve the problem, we employ recent multiple testing techniques that allow us to bound the expected fraction of false rejections at a desired level. Monte Carlo results illustrate the usefulness of the techniques. The empirical results show that the data do not support the notion of output convergence after controlling for multiplicity.
Socio-economic and demographic determinants of childhood obesity prevalence in Greece: the GRECO (Greek Childhood Obesity) study
Authors: Farajian Paul , Panagiotakos Demosthenes B , Risvas Grigoris , Karasouli Konstantina , Bountziouka Vasiliki , Voutzourakis Nikolaos , Zampelas Antonis
Published: May 2012

Objective

Given the rapid increase in the prevalence of childhood obesity, identifying the sociodemographic influences on obesity status is important for planning and implementing effective prevention initiatives. However, this type of data is limited for Greek children. Therefore the aim of the present study was to identify possible sociodemographic factors associated with childhood obesity at the national level.

Design

Cross-sectional, population-based survey, carried out from October to May 2009.

Setting

Under the context of the GRECO (Greek Childhood Obesity) study, a nationwide sample of 2315 primary-school children.

Subjects

Children aged 10–12 years and their parents were voluntarily enrolled. Direct anthropometric measurements of the children were obtained and information on sociodemographic characteristics of the parents, as well as their self-reported values of body weight and height, were collected.

Results

Overweight and obesity prevalence was 29·5 % and 13·1 %, respectively, among boys; 29·5 % and 9·0 %, respectively, among girls. Multiple logistic regression analysis revealed that the most important sociodemographic predictors of childhood obesity were mother's age, parental BMI classification and father's type of occupation. More specifically, increased mother's age and normal BMI status of the parents seemed to have a protective effect on the likelihood of having an overweight/obese child. Additionally, the odds of a female child of being overweight/obese were reduced when the father's type of occupation tended to be less manual.

Conclusions

Anti-obesity health policy interventions have to address to the parents and promote their active involvement, to effectively confront the alarming magnitude of the paediatric obesity problem in Greece.
Measurement error of waist circumference: gaps in knowledge
Authors: Verweij Lisanne M , Terwee Caroline B , Proper Karin I , Hulshof Carel TJ , van Mechelen Willem
Published: May 2012

Objective

It is not clear whether measuring waist circumference in clinical practice is problematic because the measurement error is unclear, as well as what constitutes a clinically relevant change. The present study aimed to summarize what is known from state-of-the-art research.

Design

To identify the magnitude of the measurement error of waist circumference measurements from the literature, a search was conducted in PubMed from 1975 to February 2011.

Results

The measurement error may vary between 0·7 cm and 15 cm. Taking a realistic range of measurable waist circumference into account (60–135 cm), we argue that a short-term clinically relevant change in waist circumference of 5 % may lie between 3·0 and 6·8 cm and a maintained clinically relevant change of 3 % between 1·8 and 4·1 cm.

Conclusions

Based on these results, we conclude it may be difficult to distinguish clinically relevant change from measurement error in individual subjects, due to the large measurement error and unclear definition of clinically relevant change. More research is needed to address these gaps in knowledge. To minimize measurement error, we recommend using a uniform measurement protocol, training and repeated measurements.
Overcoming Historical Injustices: Land Reconciliation in South Africa. By James L. Gibson
Authors: Nalepa Monika
Published: May 2012

Overcoming Historical Injustices: Land Reconciliation in South Africa. By James L. Gibson. New York: Cambridge University Press, 2009. 328p. $92.00.

All three of James Gibson's books on transitional justice in South Africa focus on showing that the politics of reconciliation with the Apartheid regime are less related to economic “self-interest” than to “sociotropic fairness.” On close examination, Gibson concludes that an individual's preferences about land reconciliation are not a direct function of egocentric instrumentalism. Rather, in his view, they are shaped by conceptions of whether one's group has been fairly treated.
A Plague of Initials: Fragmentation, Cohesion, and Infighting in Civil Wars
Authors: Bakke Kristin M. , Cunningham Kathleen Gallagher , Seymour Lee J. M.
Published: May 2012

How do we conceptualize the fragmentation of internally divided movements? And how does variation in fragmentation affect the probability and patterns of infighting? The internal politics of non-state groups have received increasing attention, with recent research demonstrating the importance of cohesion and fragmentation for understanding conflict dynamics. Yet there is little consensus on how to conceptualize fragmentation, the concept at the center of this agenda, with authors using different definitions and measures. In this paper we conceptualize fragmentation along three constitutive dimensions: the number of organizations in the movement; the degree of institutionalization across these organizations; and the distribution of power among them. We then show how variation across these dimensions can explain variation in important conflict processes, focusing on infighting.
New Approaches to the Study of Violence
Authors: Isaac Jeffrey C.
Published: May 2012

In his recent book The Better Angels of Our Nature: Why Violence Has Declined, Harvard psychologist Steven Pinker draws upon a wealth of data to argue that the modern world, especially since 1945, has experienced a dramatic and probably irreversible decline in organized violence. The book has received much critical attention (which will indeed be the topic of future discussion in Perspectives). It is undeniably true that recent decades have seen a decrease in the incidence of, and casualties related to, classic forms of interstate violence, and that in recent years there has been a decline in organized civil war violence as well. At the same time, it is equally true that violence—its threat, its use, its many often-unpredictable consequences—remains an ever-present part of the political landscape throughout the world. The Geneva Declaration on Armed Violence and Development's recent report, The Global Burden of Armed Violence 2011, estimates that since 2004 “more than 526,000 people are killed each year as a result of lethal violence.” The report estimates that only around one tenth of these killings—approximately 55,000 per year—are caused by “direct armed conflict,” i.e., in organized wars, whether interstate or civil. But it also estimates that hundreds of thousands more are related to gang violence, drug trafficking, transnational organized crime, and other activities that take place in a netherworld beyond law and order, and between “war” and “peace.” And it observes that while the categories typically used by governments, multilateral agencies, and NGOs to classify violence—organized vs. interpersonal, conflict-related vs. criminal—serve certain practical purposes, “these distinctions give the misleading impression that different forms and incidents of violence fit into neat and separate categories,” whereas in fact these forms of violence are not so neatly distinguished. And beyond the sphere of lethal violence lays a much broader domain of destruction, fear, insecurity, vulnerability, and harm.
Social integration in global mental health: what is it and how can it be measured?
Authors: Baumgartner J. N. , Susser E.
Published: May 2012

Purpose.

Global mental health movements increasingly highlight social integration as a key outcome for mental health services. This creates a pressing need to better articulate and measure this outcome. Much of the work in social integration thus far has been in high-income countries (HIC), and is not directly applicable across diverse socio-cultural environments. We discuss promising concepts and measures of social integration with potential for global cross-cultural application. Then, we present some of the challenges of developing measures for global and cross-cultural use, and suggest ways to confront these challenges. Although we focus primarily on adults with severe mental disorders in low- and middle-income countries (LMIC), the questions we raise are also relevant to children, other mental disorders and HIC.

Findings.

We identify and describe four distinct conceptual frameworks for social integration that have emerged over the past decade. Then, we discuss the challenge of developing corresponding measures, and the further challenge of developing global cross-cultural measures. We suggest that a key concept shared across much previous and emerging work is active participation in community and civic life. As a platform for future development of global cross-cultural measures of this and other concepts, we propose guidelines and present examples of feasible, previously used strategies.

Emerging concepts of social integration hold great promise, but as yet, there are no corresponding measures suitable for global cross-cultural use. We propose that it is feasible to develop such measures, and that their development will facilitate the advance of community mental health services and the science of global mental health.
The disease entity in psychiatry: fact or fiction?
Authors: Jablensky A.
Published: May 2012

Background.

The current debate concerning the forthcoming revisions of the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual of Mental Disorders (DSM) lacks sufficient historical perspective on groundwork concepts in psychiatry, such as the nature of the disease entity, categorical typologies, dimensional models and their validity and utility.

Objective.

To offer an overview of the evolution and metamorphoses of the conceptual basis of classification in psychiatry, with particular focus on psychotic disorders.

Method.

Discursive, proceeding from history of ideas to a critique of present dilemmas.

Results.

Much of the present-day discussion of basic issues concerning the classification of mental disorders is a replay of debates that took place in the earlier periods of scientific psychiatry.

Conclusion.

The mainstream nosological paradigm adopted in psychiatry since early 20th century is in need to be critically examined and transcended with the help of concepts and methodological tools available today.
Electron temperature in the cusp as measured with the SCIFER‐2 sounding rocket
Authors: Lund E. J. , Lessard M. R. , Sigernes F. , Lorentzen D. A. , Oksavik K. , Kintner P. M. , Lynch K. A. , Huang D. H. , Zhang B. C. , Yang H. G. , Ogawa Y.
Published: May 2012

It is expected that energy deposited by soft auroral electron precipitation in the ionosphere should result in heating of ionospheric electrons in that location, and this heating is an important step in the ion outflow process. We present coordinated observations from the SCIFER‐2 sounding rocket in the cusp region overflying optical observing sites in Svalbard. The rocket payload included a sensor which is designed to measure the temperature of thermal electrons. We show that elevated electron temperatures measured in situ are correlated with electron precipitation as inferred from auroral emissions during the 60–120 s preceding the passage of the rocket. This integrated “cooking time” is an important factor in determining the origin and resulting flux of outflowing ions.
An assessment of the surface longwave direct radiative effect of airborne dust in Zhangye, China, during the Asian Monsoon Years field experiment (2008)
Authors: Hansell Richard A. , Tsay Si‐Chee , Hsu N. Christina , Ji Qiang , Bell Shaun W. , Holben Brent N. , Welton Ellsworth J. , Roush Ted L. , Zhang W. , Huang J. , Li Zhanqing , Chen H.
Published: May 2012

In April–June 2008, NASA Goddard's ground‐based mobile laboratories (SMART‐COMMIT) were deployed to Zhangye China (39.0°N; 101°W) to support the Asian Monsoon Years field experiment and the East Asian Study of Tropospheric Aerosols and Impact on Regional Climate. One of the primary objectives at Zhangye, a semi‐arid region located between the Taklimakan and Gobi Deserts, was to capture and characterize dust aerosols near the source and to quantify their direct radiative effects (DRE). A regional dust optical model was constructed by combining previously measured soil mineralogy data at Zhangye with COMMIT's particle microphysical measurements. During a 2‐week period of heightened dust activity, retrieved longwave (LW) aerosol optical thickness (τ) from SMART's Atmospheric Emitted Radiance Interferometer was used in the Fu‐Liou radiative transfer model to derive LW instantaneous DRE (DRELW) at the surface, top of atmosphere, and heating rate profiles for cloud‐free conditions. Conservatively, surface instantaneous DRELW and LW forcing efficiency range from about 2–20 Wm−2 and 31–35 Wm−2τ−1 (0 ≤ τ ≤ 0.83), respectively. The significance of DRELWrelative to its shortwave counterpart was estimated to be between 51 and 58%, but of opposite sign, partly compensating shortwave surface cooling. Compared to Saharan dust observed during the NAMMA‐2006 field experiment at Cape Verde, dust LW forcing efficiency for this study was found to be a factor of two larger stemming from differences in environmental and surface conditions, aerosol absorption, and Zhangye's close proximity to major desert sources. Relative to observed and modeled ranges in surface DRELW for clouds (∼30–80 Wm−2) and greenhouse gases (∼2 Wm−2), this study's upper range in DRELW represents a significant perturbation to the climate system with important implications for better understanding regional changes in surface temperatures and moisture budgets.
Drought‐induced mortality of a Bornean tropical rain forest amplified by climate change
Authors: Kumagai Tomo'omi , Porporato Amilcare
Published: May 2012

Drought‐related tree mortality at a regional scale causes drastic shifts in carbon and water cycling in Southeast Asian tropical rain forests, where severe droughts are projected to occur more frequently, especially under El Niño conditions. We examine how the mortality of a Bornean tropical rain forest is altered by projected shifts in rainfall, using field measurements, global climate model (GCM) simulation outputs, and an index developed for drought‐induced tree mortality (Tree Death Indexη) associated with a stochastic ecohydrological model. All model parameters have clear physical meanings and were obtained by field observations. Rainfall statistics as primary model forcing terms are constructed from long‐term rainfall records for the late 20th century, and 14 GCM rainfall projections for the late 21st century. These statistics indicate that there were sporadic severe droughts corresponding with El Niño events, generally occurring in January–March, and that seasonality in rainfall will become more pronounced, e.g., dry (January–March) seasons becoming drier and wet (October–December) seasons becoming wetter. The computedη well reflects high tree mortality under severe drought during the 1997–1998 El Niño event. For the present, model results demonstrate high and low probabilities of mortality in January–March and October–December, respectively, and they predict that the difference in such probabilities will increase in the future. Such high probability of mortality in the dry season is still significantly high, even considering the beneficial effect of increased soil water storage in the wet season (which is projected to increase in the late 21st century).
Anaerobic oxidation of methane in tropical and boreal soils: Ecological significance in terrestrial methane cycling
Authors: Blazewicz Steven J. , Petersen Dorthe G. , Waldrop Mark P. , Firestone Mary K.
Published: May 2012

Anaerobic oxidation of methane (AOM) is a considerable sink for the greenhouse gas methane (CH4) in marine systems, but the importance of this process in terrestrial systems is less clear. Lowland boreal soils and wet tropical soils are two hot spots for CH4 cycling, yet AOM has been essentially uncharacterized in these systems. We investigated AOM in soils from sites in Alaska and Puerto Rico. Isotope tracers were utilized in vitro to enable the simultaneous quantification of CH4 production and consumption without use of biological inhibitors. Boreal peat soil and tropical mineral soil oxidized small but significant quantities of CH4 to CO2 under anoxic conditions (p < 0.001). Potential AOM rates were 21 ± 2 nmol gdw−1 d−1 and 2.9 ± 0.5 nmol gdw−1 d−1 for the boreal and tropical soils, respectively. The addition of terminal electron acceptors (NO3−, Fe(III), and SO42−) inhibited AOM and methanogenesis in both soils. In all incubations, CH4 production occurred simultaneously with AOM, and CH4 production rates were always greater than AOM rates. There was a strong correlation between the quantity of CH4 produced and the amount of CH4 oxidized under anoxic conditions (Alaska: r = 0.875, p < 0.0001; Puerto Rico: r = 0.817, p < 0.0001). CH4 oxidation under anoxic conditions was biological and likely mediated by methanogenic archaea. While only a small percentage of the total CH4 produced in these soils was oxidized under anoxic conditions (0.3% and 0.8% for Alaskan and Puerto Rican Soils), this process is important to understand since it could play a measurable role in controlling net CH4 flux.
Ionospheric and auroral clutter models for HF surface wave and over‐the‐horizon radar systems
Authors: Ravan M. , Riddolls R. J. , Adve R. S.
Published: May 2012

The detection performance of high frequency surface wave radar (HFSWR) and high frequency over‐the‐horizon radar (OTHR) systems is heavily influenced by the presence of radar clutter. In HFSWR systems, the clutter has its origins in vertical‐incidence ionospheric reflections, whereas in OTHR systems, the origin is Bragg backscatter from plasma structures in the auroral zone. This paper models the spreading of the radar clutter signal in the Doppler and angle‐of‐arrival domains that arises from forward‐scattering effects as the radar pulse propagates through regions of ionospheric plasma irregularities. The models use a geometric optics approach to determine the power spectrum of the radar signal phase. This power spectrum is then used to simulate three‐dimensional space‐time‐range radar data cubes. The accuracy of the models is tested by comparing the simulated data to measured data cubes. As an application, the data are then used to evaluate the performance of the newly developed fast fully adaptive (FFA) space‐time adaptive processing (STAP) scheme to improve the extraction of target echoes from a clutter background.
Estimating effective model parameters for heterogeneous unsaturated flow using error models for bias correction
Authors: Erdal D. , Neuweiler I. , Huisman J. A.
Published: May 2012

Estimates of effective parameters for unsaturated flow models are typically based on observations taken on length scales smaller than the modeling scale. This complicates parameter estimation for heterogeneous soil structures. In this paper we attempt to account for soil structure not present in the flow model by using so‐called external error models, which correct for bias in the likelihood function of a parameter estimation algorithm. The performance of external error models are investigated using data from three virtual reality experiments and one real world experiment. All experiments are multistep outflow and inflow experiments in columns packed with two sand types with different structures. First, effective parameters for equivalent homogeneous models for the different columns were estimated using soil moisture measurements taken at a few locations. This resulted in parameters that had a low predictive power for the averaged states of the soil moisture if the measurements did not adequately capture a representative elementary volume of the heterogeneous soil column. Second, parameter estimation was performed using error models that attempted to correct for bias introduced by soil structure not taken into account in the first estimation. Three different error models that required different amounts of prior knowledge about the heterogeneous structure were considered. The results showed that the introduction of an error model can help to obtain effective parameters with more predictive power with respect to the average soil water content in the system. This was especially true when the dynamic behavior of the flow process was analyzed.
Communication Disorders in Ethiopia: Emerging Needs and New Models of Development
Authors: Domsch Celeste
Published: May 2012

In this article, the author considers the state of communication disorders in Ethiopia today by first discussing the health status of adults and children, particularly as it relates to the prevalence of neurologic and communication disorders. The author goes on to describe new models of treatment for communication and related disorders and the current system of health-care delivery. Next, the author examines the multilingual nature of education in Ethiopia. The article concludes with a consideration of the language development of internationally adopted children, as well as the expected influence of Amharic on English production in mature bilingual speakers.
General formulation of spin-flip time-dependent density functional theory using non-collinear kernels: Theory, implementation, and benchmarks
Authors: Bernard Yves A. , Shao Yihan , Krylov Anna I.
Published: May 2012

We report an implementation of the spin-flip (SF) variant of time-dependent density functional theory (TD-DFT) within the Tamm-Dancoff approximation and non-collinear (NC) formalism for local, generalized gradient approximation, hybrid, and range-separated functionals. The performance of different functionals is evaluated by extensive benchmark calculations of energy gaps in a variety of diradicals and open-shell atoms. The benchmark set consists of 41 energy gaps. A consistently good performance is observed for the Perdew-Burke-Ernzerhof (PBE) family, in particular PBE0 and PBE50, which yield mean average deviations of 0.126 and 0.090 eV, respectively. In most cases, the performance of original (collinear) SF-TDDFT with 50-50 functional is also satisfactory (as compared to non-collinear variants), except for the same-center diradicals where both collinear and non-collinear SF variants that use LYP or B97 exhibit large errors. The accuracy of NC-SF-TDDFT and collinear SF-TDDFT with 50-50 and BHHLYP is very similar. Using PBE50 within collinear formalism does not improve the accuracy.
Magnetic bit stability: Competition between domain-wall and monodomain switching
Authors: Hoffman Silas , Tserkovnyak Yaroslav , Khalili Amiri Pedram , Wang Kang L.
Published: May 2012

We numerically study the thermal stability properties of computer memory storage realized by a magnetic ellipse. In the case of practical magnetic random-access memory devices, the bit can form a spin texture during switching events. To study the energy barrier for thermally induced switching, we develop a variational procedure to force the bit to traverse a smooth path through configuration space between the points of stability. We identify textured configurations realizing domain-wall propagation, which may have an energy barrier less than that of the corresponding monodomain model. We contrast the emergence of such micromagnetic effects in thermal versus field-induced switching.
Measurement of bonding energy in an anhydrous nitrogen atmosphere and its application to silicon direct bonding technology
Authors: Fournel F. , Continni L. , Morales C. , Da Fonseca J. , Moriceau H. , Rieutord F. , Barthelemy A. , Radu I.
Published: May 2012

Bonding energy represents an important parameter for direct bonding applications as well as for the elaboration of physical mechanisms at bonding interfaces. Measurement of bonding energy using double cantilever beam (DCB) under prescribed displacement is the most used technique thanks to its simplicity. The measurements are typically done in standard atmosphere with relative humidity above 30%. Therefore, the obtained bonding energies are strongly impacted by the water stress corrosion at the bonding interfaces. This paper presents measurements of bonding energies of directly bonded silicon wafers under anhydrous nitrogen conditions in order to prevent the water stress corrosion effect. It is shown that the measurements under anhydrous nitrogen conditions (less than 0.2 ppm of water in nitrogen) lead to high stable debonding lengths under static load and to higher bonding energies compared to the values measured under standard ambient conditions. Moreover, the bonding energies of Si/SiO2 or SiO2/SiO2 bonding interfaces are measured overall the classical post bond annealing temperature range. These new results allow to revisit the reported bonding mechanisms and to highlight physical and chemical phenomena in the absence of stress corrosion effect.
Full-band Monte Carlo simulation of high-energy carrier transport in single photon avalanche diodes with multiplication layers made of InP, InAlAs, and GaAs
Authors: Dolgos Denis , Meier Hektor , Schenk Andreas , Witzigmann Bernd
Published: May 2012

We investigate the high-energy charge dynamics of electrons and holes in the multiplication process of single photon avalanche diodes. The technologically important multiplication layer materials InP and In0.52Al0.48As, used in near infrared photon detectors, are analyzed and compared with GaAs. We use the full-band Monte Carlo technique to solve the Boltzmann transport equation which improves the state-of-the-art treatment of high-field carrier transport in the multiplication process. As a result of the computationally efficient treatment of the scattering rates and the parallel central processing unit power of modern computer clusters, the full-band Monte Carlo calculation of the breakdown characteristics has become feasible. The breakdown probability features a steeper rise versus the reverse bias for smaller multiplication layer widths for InP, In0.52Al0.48As, and GaAs. Both the time to avalanche breakdown and jitter decrease with shrinking size of the multiplication region for the three examined III–V semiconductors.
Chemical and topological order in shear bands of Cu64Zr36 and Cu36Zr64 glasses
Authors: Ritter Yvonne , Albe Karsten
Published: May 2012

Shear bands in binary Cu64Zr36 and Cu36Zr64 metallic glasses are studied by molecular dynamics simulations with respect to their chemical and topological short range order. In both glasses, shear band formation goes along with an increase in excess volume inside the shear band. Only in the Cu-rich alloy, where Cu-centered icosahedra represent the most abundant topological unit, the dilatation within the shear band is related to a decrease in the number of icosahedral units, while the degree of cross-linking and the cluster size decrease when a shear band forms. In the Cu36Zr64 glass, in contrast, no topological feature changes when the material starts yielding and a shear band is formed. The chemical short range order, however, is affected in both materials within the shear band, which is revealed by an increase in the number of Cu–Cu and Zr–Zr bonds. Since all structural modifications are rather the result of plastic deformation than a pre-requisite, we conclude that the presence of distinct topological features, such as icosahedral units, is not a pre-requisite for shear band formation.
Dislocation climb in two-dimensional discrete dislocation dynamics
Authors: Davoudi Kamyar M. , Nicola Lucia , Vlassak Joost J.
Published: May 2012

In this paper, dislocation climb is incorporated in a two-dimensional discrete dislocation dynamics model. Calculations are carried out for polycrystalline thin films, passivated on one or both surfaces. Climb allows dislocations to escape from dislocation pile-ups and reduces the strain-hardening rate, especially for fully passivated films. Within the framework of this model, climb modifies the dislocation structures that develop during plastic deformation and results in the formation of pile-ups on slip planes that do not contain any dislocation sources.
Kubo-Greenwood approach for the calculation of mobility in gate-all-around nanowire metal-oxide-semiconductor field-effect transistors including screened remote Coulomb scattering—Comparison with experiment
Authors: Dura J. , Triozon F. , Barraud S. , Munteanu D. , Martinie S. , Autran J. L.
Published: May 2012

In this paper, we present a theory of electron mobility in nanowire metal-oxide-semiconductor field-effect transistors (MOSFETs). Numerical approach consists of the Kubo-Greenwood formula and the self-consistent solution of the Schrödinger and Poisson equations for cylindrical gated nanowires. Phonons and surface roughness scatterings are treated in accordance with literature. Moreover, this paper focuses on nanowire MOSFETs using a high-k/metal gate stack. This configuration is chosen to be as close as possible to experimental investigations. The impact of trapped charges in the oxide, called remote Coulomb scattering, is modeled following the Kubo-Greenwood approach and accounting for screening effect. A comparison with experiment is performed for a single cylindrical nanowire with diameter of 20 nm. The diameter dependence is highlighted and it is shown that silicon thickness has a great impact on the mobility for diameters below 10 nm.