bluuebunny/crossref_metadata_2025 huggingface dataset:
A service‐based runtime environment for native applications
Authors: Al‐Gahmi Abdulmalik , Cook Jonathan
Published: December 2009

Unlike interpreted application programs that run within the rich runtime environment of their own interpreters, natively compiled application programs are typically thought of as executing on the barebones runtime environment provided by their own operating systems and dynamic linkers. This article presents the notion of a service‐based runtime (SBRT) environment for natively compiled application programs, in which the current dynamic linker is only a core service and other extensive middleware‐type services are available to the running application program. It then describes a dynamic‐linker‐based implementation of such an environment, calleddlSBRT.dlSBRTimplements a unified interface that allows it to be extensible by means of extension dynamic services. Implemented examples of such services are presented and the performance ofdlSBRT, when such example services are deployed, is evaluated. Copyright © 2009 John Wiley & Sons, Ltd.
Disruption of Bis Leads to the Deterioration of the Vascular Niche for Hematopoietic Stem Cells
Authors: Kwon Kyung-rim , Ahn Ji-Yeon , Kim Myung-Shin , Jung Joo-Young , Lee Jeong-Hwa , Oh Il-Hoan
Published: December 2009

The stem cell niche plays an important role in the microenvironmental regulation of hematopoietic stem cells, but the integration of niche activity remains poorly understood. In this study, we show that a functional deficiency of Bis/BAG-3/CAIR-1, a protein related to apoptosis and the response to cellular stress, results in perturbation of the vascular stem cell niche, causing a series of hematopoietic derangements. Mice with a targeted disruption of bis (bis−/−) exhibited a loss of hematopoietic stem cells and defective B-cell development. However, this hematological defect of bis−/− mice was not reproduced when bis−/− bone marrow cells were transplanted into bis+/+ recipients. Moreover, bis+/+ bone marrow cells, when transplanted into bis−/− mice, reproduced the same defect as bis−/− cells, pointing to the microenvironmental origin of the phenotypes. Subsequent analysis of bis−/− mice bone marrow revealed a characteristic defect in the vascular stem cell niche that included the defective growth of stromal progenitor cells in colony forming unit-fibroblasts, the defect in sinusoidal endothelium, and the loss of stromal cells expressing CXCL-12 or IL-7 in the bone marrow. In contrast, no abnormalities were observed in the growth and hematopoietic supporting activities of osteoblasts from bis−/− mice bone marrows. Collectively, these results indicate that Bis functions to mediate cellular regulation of the stem cell niche on the vascular compartment and suggest that the vascular and osteoblastic compartments of the stem cell niche can be independently regulated during the in vivo orchestration of hematopoiesis.
Use of rotational friction dampers to enhance seismic and progressive collapse resisting capacity of structures
Authors: Kim J. , Choi H. , Min K‐W.
Published: December 2009

Passive energy dissipation devices are generally used to reduce structural responses caused by earthquake or wind loads. This study presents combined system of rotational friction dampers connected to high strength tendons to enhance both seismic and progressive collapse‐resisting capacity of existing structures. Friction dampers were designed using the capacity spectrum method to satisfy given performance objectives against seismic load, and their seismic‐ and progressive collapse‐resisting capacities were investigated. According to the nonlinear dynamic analysis results, the structures retrofitted with rotational friction dampers generally satisfied the given performance objectives against seismic load. Both the nonlinear static and dynamic analysis results showed that the progressive collapse potential of the model structures was significantly enhanced as a result of the seismic retrofit. Copyright © 2009 John Wiley & Sons, Ltd.
Social neuroscience
Authors: Norman Greg J. , Cacioppo John T. , Berntson Gary G.
Published: December 2009

Social species, by definition, create emergent organizations beyond the individual that range in humans from dyads, families, and groups to cities, civilizations, and cultures. These emergent structures evolved hand‐in‐hand with neural, hormonal, and genetic mechanisms to support them because the consequent social behaviors helped these organisms survive, reproduce, and care for offspring sufficiently long that they too survived to reproduce. Social neuroscience is concerned with investigating these emergent structures and the underlying neural, hormonal, and genetic mechanisms that make them possible. As such, it represents an interdisciplinary approach devoted to understanding how biological systems implement social processes and behavior, and to using biological concepts and methods to inform and refine theories of social processes and behavior. Copyright © 2009 John Wiley & Sons, Ltd.

This article is categorized under:

Neuroscience > Behavior
Risk attitude and preference
Authors: Weber Elke U.
Published: December 2009

Citizens of Western countries are asked to make an increasing number of decisions that involve risk, from decisions about how much and how to save for their old age to choices among medical treatments and medical insurance plans. At the same time, uncertainty about choice outcomes has gone up as the result of ever faster social, environmental, and technological change. Accuracy in predicting what choices people will make, at least in the aggregate, is an important determinant for the success of public policy interventions. In addition, corporate and public policy often tries to influence and modify people's choices in the face of risk and uncertainty, for example, getting people to save more of their income or getting women to invest in less conservative instruments. Understanding the processes that underlie risky decisions and the drivers of risk taking is critical to both agendas. Copyright © 2009 John Wiley & Sons, Ltd.

This article is categorized under:

Economics > Individual Decision-Making

Psychology > Reasoning and Decision Making
Nutritional composition and digestibility by ocelots (Leopardus pardalis) of whole animals and a commercial diet
Authors: Bennett Cynthia L. , Booth‐Binczik Susan D. , Steele Suzy R. E.
Published: December 2009

Felids are adapted to eat whole prey, but in North American zoos are usually fed processed diets based on muscle meat. We analyzed proximate nutrient composition and digestibility by ocelots of a commercial processed diet and whole animals of five species. The processed diet did not differ significantly from the whole animals in proximate composition, although it was at one end of the range of results for all nutrients. Domestic chicks were significantly lower than all other dietary items tested in digestibility of energy and fat, and lower than rabbits and quail in digestibility of dry matter. There were no other significant differences. These results suggest that the commercial diet tested provides an appropriate nutritional environment for ocelots with respect to proximate constituents. Studies of vitamin and mineral composition and digestibility and comparisons to wild prey species should be conducted to permit a full evaluation. Zoo Biol 29:753–759, 2010. © 2009 Wiley‐Liss, Inc.
Application of small interfering RNAs modified by unlocked nucleic acid (UNA) to inhibit the heart‐pathogenic coxsackievirus B3
Authors: Werk Denise , Wengel Jesper , Wengel Suzy L. , Grunert Hans-Peter , Zeichhardt Heinz , Kurreck Jens
Published: December 2009

This study describes the first application of unlocked nucleic acid (UNA)‐modified small interfering RNAs (siRNAs) directed against a medically relevant target, the coxsackievirus B3. We systematically analyzed the impact of different siRNA modification patterns and observed good compatibility of the introduction of UNA with the maintenance of high antiviral activity. Additionally, the polarity of an siRNA was successfully reversed by modulating the relative stability of the termini with locked nucleic acid (LNA) and UNA as shown in a reporter assay. The potency of the reversed siRNA against the full‐length target was, however, too low to inhibit the infectious virus. Altogether, combined modification of siRNAs with LNA und UNA provides a promising approach to alter and improve properties of an siRNA.
Effectiveness of an instructional DVD on third‐ and fourth‐degree laceration repair for obstetrics and gynecology postgraduate trainees
Authors: Chao Tamara T. , Wendel George D. , McIntire Donald D. , Corton Marlene M.
Published: December 2009

Objective

To assess the effectiveness of an instructional DVD on the anatomy and repair of anal sphincter lacerations to improve postgraduate trainees’ understanding.

Methods

A total of 71 obstetrics and gynecology trainees completed a pretest of third‐ and fourth‐degree lacerations to assess baseline knowledge and perceptions. Question categories included anatomy, antibiotics, anesthesia, repair methods, complications, postoperative care, and risk factors. After 1 year of clinical experience, 67 trainees (94%) were randomly assigned into DVD (intervention) and non‐DVD (control) groups. A post‐test was administered 4 weeks later.

Results

In the DVD group (n = 34), mean scores on the pretest versus the post‐test were 65% vs 74% for postgraduate year (PGY)‐1 (P = 0.09); 72% vs 83% for PGY‐2 (P = 0.06); 67% vs 83% for PGY‐3 (P = 0.01); and 75% vs 87% for PGY‐4 (P < 0.001). In the non‐DVD group (n = 33), mean scores did not change significantly for any year level. The increase in score from pretest to post‐test was significantly different between the 2 groups, independent of year (P < 0.001). DVD group scores improved significantly over non‐DVD group scores in anatomy (P = 0.005) and repair methods (P = 0.042) subscales.

Conclusion

An educational video is an effective tool for improving understanding of third‐ and fourth‐degree lacerations for physicians‐in‐training.
Perioperative and long‐term complications among obese women undergoing vaginal surgery
Authors: Nam Ka‐Hyun , Jeon Myung‐Jae , Hur Hye‐Won , Kim Sei‐Kwang , Bai Sang‐Wook
Published: December 2009

Objective

To determine whether obesity influenced the risk of perioperative and long‐term complications in patients undergoing vaginal surgery.

Methods

Women diagnosed with pelvic organ prolapse who underwent vaginal surgery between March 1999 and May 2007 were classified into 3 groups: normal weight (body mass index [BMI, calculated as weight in kilograms divided by the square of height in meters] 18.5–23.0); overweight (BMI 23.0–27.5); and obese (BMI ≥ 27.5). Complications were subdivided into perioperative (< 1 month) and long‐term (≥ 1 month). Statistical analysis was performed using analysis of variance, χ2 test, and logistic regression.

Results

Demographic information showed no differences among the groups, except for the presence of comorbidity (P = 0.03). Blood loss and transfusion as a perioperative complication and urinary retention as a long‐term complication were significantly different among the groups: odds ratio (OR) 2.46 (95% confidence interval [CI], 1.38–4.39; P < 0.01); and OR 2.20 (95% CI, 1.21–4.03; P = 0.03), respectively.

Conclusion

Major complications were rare, and most were not significantly different among the groups. However, obesity was a protective factor against blood loss and transfusion, and long‐term urinary retention.
The role of the media in electoral behaviour: A Canadian perspective
Authors: Nesbitt-Larking Paul W
Published: December 2009

This work, divided in four sections, is a critical assessment of Canadian perspectives on the role of the media in electoral behaviour, notably on the roles media play in setting or responding to the agenda in the heat of election campaigns. The first section of the article highlights important Canadian methodological and empirical contributions to behaviouralism. The second section of the article, on culture, ideology, and discourse, illustrates general patterns of contrast between the Canadian and American political cultures through an exploration of the comparative role of negative and attack advertisements in election campaigns. The third section of the article illustrates how facets of the Political Economy of Canada exert an impact on media/campaign interactions. The fourth and final section of the article undertakes the task of situating media/campaign interactions within the legal-institutional regulatory context of the Canadian state. Here, while the potential impact on media content is apparent, the critical approach to the role of the media incorporates both the unacknowledged conditions and the unanticipated outcomes of the regulatory apparatus.
Sensitivity to long-term climate change of subpermafrost groundwater systems in Svalbard
Authors: Haldorsen Sylvi , Heim Michael , Dale Barrie , Landvik Jon Y. , van der Ploeg Martine , Leijnse Anton , Salvigsen Otto , Hagen Jon Ove , Banks David
Published: December 2009

Deep subpermafrost aquifers are highly climate-dependent, with the permafrost as an aquitard preventing groundwater recharge and discharge. A study from the high-arctic island of Spitsbergen, Svalbard, shows that during a glacial to interglacial phase, both the permafrost and the glacier regime will respond to climatic changes, and a glacier-fed groundwater flow system will vary accordingly. A full glaciation results in the melting of permafrost, and groundwater can flow through pores and fracture systems in the rocks and sediments below the temperate zones of glaciers. These groundwater flow systems will mainly be localized to fjords and valleys and form low-lying terrestrial springs when the relative sea level drops during deglaciation due to glacio-isostatic rise. During an interglaciation, permafrost develops and thickens and the groundwater recharge and discharge areas will thereby be gradually reduced to a minimum reached at the warmest part of an interglaciation. An already frozen spring system cannot reopen before the permafrost melts. Only groundwater springs related to permanently warm-based glacial ice will persist into the next glaciation. During a new glaciation, flow systems that terminated during the previous interglaciation may become revitalized if overridden by warm-based ice causing permafrost thawing.
A BIT Is Better Than a Lot: Bilateral Investment Treaties and Preferential Trade Agreements
Authors: Tobin Jennifer L. , Busch Marc L.
Published: December 2009

The landscape of the global economy is dotted with institutions that regulate investment and trade. In recent years, the number of bilateral investment treaties (BITs) and preferential trade agreements (PTAs), in particular, has grown at a torrid pace; practically every country is a member of at least one—if not many—of these institutions. For all the scholarly attention that these institutions have received, however, there is little research tying BITs and PTAs together. This is surprising, since both aim to increase commerce by making it more predictable. The authors seek to fill this gap in the literature. They argue that a BIT between a developed and a developing country should make it more likely that this pair of states will subsequently form a PTA. That said, the wrinkle in the story is that more is not better in this regard; the authors further argue that a developing country that has many BITs is less likely to conclude a PTA with a wealthy state. The authors test these hypotheses using annual data on pairs of developing and developed countries between 1960 and 2004 and find strong evidence in support of their argument.
Defeating Dictators: Electoral Change and Stability in Competitive Authoritarian Regimes
Authors: Bunce Valerie J. , Wolchik Sharon L.
Published: December 2009

What explains electoral stability and change in competitive authoritarian regimes? This article addresses the question by comparing eleven elections—six of which led to continuity in authoritarian rule and five of which led to the victory of the opposition—that took place between 1998 and 2008 in competitive authoritarian regimes countries located in the postcommunist region. Using interviews conducted with participants in all of these elections and other types of data and constructing a research design that allowed the authors to match these two sets of elections on a number of important dimensions, they assess two groups of hypotheses—those that highlight institutional, structural, and historical aspects of regime and opposition strength on the eve of these elections and others that highlight characteristics of the elections themselves. The authors conclude that the key difference was whether the opposition adopted a tool kit of novel and sophisticated electoral strategies that made them more popular and effective challengers to the regime.
Why Do Ethnic Groups Rebel? New Data and Analysis
Authors: Cederman Lars-Erik , Wimmer Andreas , Min Brian
Published: December 2009

Much of the quantitative literature on civil wars and ethnic conflict ignores the role of the state or treats it as a mere arena for political competition among ethnic groups. Other studies analyze how the state grants or withholds minority rights and faces ethnic protest and rebellion accordingly, while largely overlooking the ethnic power configurations at the state's center. Drawing on a new data set on Ethnic Power Relations (EPR) that identifies all politically relevant ethnic groups and their access to central state power around the world from 1946 through 2005, the authors analyze outbreaks of armed conflict as the result of competing ethnonationalist claims to state power. The findings indicate that representatives of ethnic groups are more likely to initiate conflict with the government (1) the more excluded from state power they are, especially if they have recently lost power, (2) the higher their mobilizational capacity, and (3) the more they have experienced conflict in the past.
After KKV: The New Methodology of Qualitative Research
Authors: Mahoney James
Published: December 2009

This article discusses developments in the field of qualitative methodology since the publication of King, Keohane, and Verba's (KKV's) Designing Social Inquiry. Three areas of the new methodology are examined: (1) process tracing and causal-process observations; (2) methods using set theory and logic; and (3) strategies for combining qualitative and quantitative research. In each of these areas, the article argues, the new literature encompasses KKV's helpful insights while avoiding their most obvious missteps. Discussion focuses especially on contrasts between the kind of observations that are used in qualitative versus quantitative research, differences between regression-oriented approaches and those based on set theory and logic, and new approaches for bringing out complementarities between qualitative and quantitative research. The article concludes by discussing research frontiers in the field of qualitative methodology.
A social and self-reflective approach to MALL
Authors: Ros i Solé Cristina , Calic Jelena , Neijmann Daisy
Published: December 2009

There is a growing recognition that learning is increasingly taking place on the move and located beyond educational environments, ‘in the gaps of daily life’ (Sharples et al., 2007). And yet, language learners have mostly been perceived as being fixed in particular contexts, whether in the educational environment, abroad, or in their homes and communities. As several authors have pointed out (Castells et al., 2007; Okabe & Ito, 2006; Sharples et al., 2007), mobile devices allow learners to capitalize on the multiple sites that they travel through, whether they be public or private spaces, formal or informal ones, and reflect on their social practices and their learner selves. This paper investigates whether such a context-sensitive and social-oriented approach to Mobile Assisted Language Learning (MALL) can be applied to the language learning context and how it is manifested. In order to carry out this investigation, we will be drawing on literature on the development of identity in second language learning (Norton, 2000; Kramsch, 2006; Phipps, 2007) and the use of ethnographic approaches to data collection and interpretation. We will be reporting on two case studies, involving learners of Icelandic and Serbian/Croatian, conducted over two years at a UK university. The paper concludes that the use of mobile technology enables language learners to use these devices as ‘a prosthesis of the self’ (Kress & Pachler, 2007) which allows them to explore the perception of their L2 selves in a variety of day-to-day scenarios.
Utilizing lexical data from a Web-derived corpus to expand productive collocation knowledge
Authors: Wu Shaoqun , Witten Ian H. , Franken Margaret
Published: December 2009

Collocations are of great importance for second language learners, and a learner’s knowledge of them plays a key role in producing language fluently (Nation, 2001: 323). In this article we describe and evaluate an innovative system that uses a Web-derived corpus and digital library software to produce a vast concordance and present it in a way that helps students use collocations more effectively in their writing. Instead of live search we use an off-line corpus of short sequences of words, along with their frequencies. They are preprocessed, filtered, and organized into a searchable digital library collection containing 380 million five-word sequences drawn from a vocabulary of 145,000 words. Although the phrases are short, learners can browse more extended contexts because the system automatically locates sample sentences that contain them, either on the Web or in the British National Corpus. Two evaluations were conducted: an expert user tested the system to see if it could generate suitable alternatives for given text fragments, and students used it for a particular exercise. Both suggest that, even within the constraints of a limited study, the system could and did help students improve their writing.
Wie stark sind Erwachsene mit ADHS und komorbiden Störungen in ihrer gesundheitsbezogenen Lebensqualität beeinträchtigt?
Authors: Schmidt Sören , Waldmann Hans-Christian , Petermann Franz , Brähler Elmar
Published: December 2009

Hintergrund: Zur ADHS bei Erwachsenen liegen nur wenige Studien vor, die den Zusammenhang zwischen einer ADHS und komorbiden Störung erheben und mit der gesundheitsbezogenen Lebensqualität in Verbindung bringen. Methode: Die Teilnehmer der Studie wurden per Kreuzklassifikation in Gruppen unterteilt, nachdem sie als auffällig oder unauffällig eingestuft wurden. Neben χ2-Tests und korrelativen Beziehungen wurden prädiktive Werte und das relative Risiko bestimmt, um den Zusammenhang zwischen ADHS, komorbiden Störungen und der gesundheitsbezogenen Lebensqualität zu ermitteln. Ergebnisse: Während bei wenigen und begrenzten ADHS-Symptomen kaum komorbide Störungen festzustellen waren, so treten in der Hälfte aller Fälle von ADHS weitere psychische Belastungsfaktoren auf. Dabei hatten ADHS-Betroffene ein deutlich höheres Risiko für das Vorliegen psychischer Beschwerden als die Nichtbetroffenen. Diskussion: ADHS ist mit erhöhter psychischer Belastung bei gleichzeitiger Abnahme der gesundheitsbezogenen Lebensqualität verbunden. Neben dem generellen Nachweis einer hohen psychischen Belastung bei ADHS hat dies wichtige Konsequenzen für Diagnostik und Therapie. So ist eine umfassende Differenzialdiagnostik nötig, damit eine Therapie auch komorbide Störungen einbeziehen kann und sich somit die gesundheitsbezogene Lebensqualität verbessern lässt.
ADHS im Jugendalter
Authors: Tischler Lars , Schmidt Sören , Petermann Franz , Koglin Ute
Published: December 2009

Ausgehend von der Betrachtung der ADHS als Lebensspannenerkrankung geht die vorliegende Studie der Frage nach, inwieweit Symptome einer adulten Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) bereits im Jugendalter auftreten und Folgen für die klinische Praxis haben. Auf der Basis einer Repräsentativdatenerhebung wurde eine Stichprobe von N = 140 Jungen und Mädchen im Alter zwischen 14 und 19 Jahren erhoben. Mittels der eingesetzten Verfahren ADHS-E, SF-12, SWLS und PHQ-15 und PHQ-9 wurden Zusammenhänge zwischen den ADHS-Symptomen im Erwachsenenalter und Lebenszufriedenheit bzw. Lebensqualität über psychische und körperliche Symptome bei Heranwachsenden untersucht. Dabei konnte die ADHS als ein wesentlicher Faktor für die Beeinträchtigung der Lebenszufriedenheit und Begünstigung von Depressivität in der Adoleszenz ausgemacht werden. Für die klinische Praxis ergibt sich daraus ein veränderter Blickwinkel auf die Lebenszufriedenheit von Jugendlichen im Allgemeinen und auf zusätzliche psychische Belastungen im Rahmen einer adoleszenten Form der ADHS im Besonderen.
Kognitiv-behaviorale Strategien in der Behandlung von Erwachsenen mit ADHS
Authors: Elsässer Marina , Nyberg Elisabeth , Stieglitz Rolf-Dieter
Published: December 2009

Neben der Psychopharmakotherapie mit Stimulanzien ist Psychotherapie ein wichtiger Teil der ADHS-Behandlung bei Erwachsenen. Folgende Zielbereiche werden psychotherapeutisch behandelt: Unaufmerksamkeit und Vergesslichkeit, Impulsivität, Hyperaktivität, Desorganisation, dysfunktionale Kognitionen, Gefühlsregulation, Stresstoleranz, Selbstwertgefühl, Kommunikation und Komorbiditäten. Im Beitrag soll ein Überblick zu den psychotherapeutischen Techniken gegeben werden, die in der Behandlung der ADHS bei Erwachsenen verwendet werden.
Lebt es sich im Internet leichter?
Authors: Blumer Tim , Renneberg Babette
Published: December 2009

Interpersonelle Probleme im Störungsbild der Borderline-Persönlichkeitsstörung (BPS), insbesondere die Nähe-Distanz-Problematik, lassen vermuten, dass Betroffene die Anonymität des Internet bevorzugt als soziales Umfeld suchen. Über Internetforen und Diskussionsgruppen wurden 244 Teilnehmer akquiriert, die den Fragebogen zu Gedanken und Gefühlen (FGG; Renneberg, Schmidt-Rathjens, Hippin, Backenstrass & Fydrich, 2005 ), ein Instrument zur Erfassung borderline-spezifischer Kognitionen, sowie einen Fragebogen zur Internetnutzung beantworteten. Es zeigte sich, dass Teilnehmende mit hohen FGG-Werten häufiger Chats, Instant Messengers und Blogs verwenden als Teilnehmende mit niedrigen Werten. Eine explorative Hauptkomponenten-Analyse über die gesamte Gruppe der Teilnehmer ermittelte zudem sechs Bereiche sozialer Interaktion, bei denen sich zeigte, dass Teilnehmer mit borderline-spezifischen Kognitionen für drei dieser Bereiche (Nähe zulassen, Bekanntschaften machen, Unterstützung finden) das Internet als Setting signifikant häufiger vorziehen als Teilnehmer ohne borderline-spezifische Kognitionen. Die Frage, ob sie sich in der Welt des Internet generell leichter zurechtfinden als in der Realität, beantworteten Teilnehmer mit borderline-spezifischen Kognitionen 15-mal häufiger mit «Ja» als Teilnehmer ohne borderline-spezifische Kognitionen.
Importance of adsorption for CCN activity and hygroscopic properties of mineral dust aerosol
Authors: Kumar Prashant , Nenes Athanasios , Sokolik Irina N.
Published: December 2009

This study uses published data on dust‐water interactions to examine the importance of including water adsorption effects when describing the hygroscopic and cloud condensation nuclei (CCN) behavior of mineral dust aerosol. Adsorption activation theory (AT) better represents fresh dust‐water interactions than Köhler theory (KT), as i) a consistent set of adsorption parameters can describe the hygroscopic behavior of dust (under both sub and supersaturated conditions), and ii) the dependence of critical supersaturation, sc, with particle dry diameter, Ddry, is closer to observations. The long adsorption timescale could also contribute to the large differences observed between dry and wet generated dust hygroscopicity. If KT and AT are consistently applied to the same dust size distribution, KT predicts up to tenfold higher CCN and 40% higher droplet number concentration than AT. This profoundly different behavior between the theories suggests that both may be required for a comprehensive description of atmospheric dust CCN activity.
Relative humidity dependence of light absorption by mineral dust after long‐range atmospheric transport from the Sahara
Authors: Lack Daniel A. , Quinn Patricia K. , Massoli Paola , Bates Timothy S. , Coffman Derek , Covert David S. , Sierau Berko , Tucker Sara , Baynard Tahllee , Lovejoy Edward , Murphy Daniel M. , Ravishankara A. R.
Published: December 2009

The relative humidity (RH) dependence of light absorption for a Saharan dust‐dominated air mass transported to the Gulf of Mexico was measured during the 2006 TexAQS/GoMACCS study using a photo‐acoustic absorption spectrometer (PAS). Aerosol absorption was measured at low (25%) and high (73%) RH indicating a 1.5(±0.3) absorption enhancement [f(RHAbs)] under high RH conditions. f(RHAbs) estimates, based on air‐mass physical and optical properties and Mie theory modeling, were between 1.2–1.4. Reasons for differences between the measured and modeled f(RHAbs) are discussed. The mass absorption coefficient of the long‐range transported dust was calculated to be 0.04(±0.02) m2g−1.
Effect of exponential decay in hydraulic conductivity with depth on regional groundwater flow
Authors: Jiang Xiao‐Wei , Wan Li , Wang Xu‐Sheng , Ge Shemin , Liu Jie
Published: December 2009

Regional groundwater flow is critical for understanding a variety of geologic processes. Unfortunately, few studies have considered the impact of gradual decrease in hydraulic conductivity (K) with depth on groundwater flow. In this study, regional groundwater flow through a basin is analyzed under conditions of exponentially decaying K with depth. We found that the development of local versus regional flow systems is sensitive to the decay exponent of K. With higher rates of decrease in K with depth, the penetration depth of local flow systems increases, the regional flow weakens, the amount of recharge decreases, and less water reaches the regional discharge zone. Therefore, the depth decay of K should not be neglected when analyzing hydrologic problems related to regional groundwater flow.
NO2 lidar profile measurements for satellite interpretation and validation
Authors: Volten H. , Brinksma E. J. , Berkhout A. J. C. , Hains J. , Bergwerff J. B. , Van der Hoff G. R. , Apituley A. , Dirksen R. J. , Calabretta‐Jongen S. , Swart D. P. J.
Published: December 2009

Satellite instruments are efficient detectors of air pollutants such as NO2. However, the interpretation of satellite retrievals is not a trivial matter. We describe a novel instrument, the RIVM NO2 mobile lidar, to measure tropospheric NO2 profiles for the interpretation and validation of satellite data. During the DANDELIONS campaign in 2006 we obtained an extensive collection of lidar NO2 profiles, coinciding with OMI and SCIAMACHY overpasses. On clear days and early mornings a comparison between lidar and in situ measurements showed excellent agreement. At other times the in situ monitors with molybdenum converters suffered from NOy interference. The lidar NO2 profiles indicated a well‐mixed boundary layer, with high NO2 concentrations in the boundary layer and concentrations above not differing significantly from zero. The boundary layer concentrations spanned a wide range, which likely depends on the wind directions and on the intensity of local (rush hour) traffic which varies with the day of the week. Large diurnal differences were mainly driven by the height of the boundary layer, although direct photolysis or photochemical processes also contribute. Small‐scale temporal and spatial variations in the NO2 concentrations of the order of 20–50% were measured, probably indicative of small‐scale eddies. A preliminary comparison between satellite and lidar data shows that the satellite data tend to overestimate the amount of NO2 in the troposphere compared to the lidar data.
Transfer–messenger RNA controls the translation of cell‐cycle and stress proteins in Streptomyces
Authors: Barends Sharief , Zehl Martin , Bialek Sylwia , de Waal Ellen , Traag Bjørn A , Willemse Joost , Jensen Ole Nørregaard , Vijgenboom Erik , van Wezel Gilles P
Published: December 2009

The transfer–messenger RNA (tmRNA)‐mediated trans‐translation mechanism is highly conserved in bacteria and functions primarily as a system for the rescue of stalled ribosomes and the removal of aberrantly produced proteins. Here, we show that in the antibiotic‐producing soil bacterium Streptomyces coelicolor, trans‐translation has a specialized role in stress management. Analysis of proteins that were carboxy‐terminally His8‐tagged by a recombinant tmRNA identified only 10 targets, including the stress proteins: DnaK heat‐shock protein 70, thiostrepton‐induced protein A, universal stress protein A, elongation factor Tu3, and the cell‐cycle control proteins DasR, SsgA, SsgF and SsgR. Although tmRNA‐tagged proteins are degraded swiftly, the translation of dnaK and dasR messenger RNAs (mRNAs) depends fully on tmRNA, whereas transcription is unaffected. The data unveil a surprisingly dedicated functionality for tmRNA, promoting the translation of the same mRNA it targets, at the expense of sacrificing the first nascent protein. In streptomycetes, tmRNA has evolved into a dedicated task force that ensures the instantaneous response to the exposure to stress.
Observations of Earth space by self-powered stations in Antarctica
Authors: Mende S. B. , Rachelson W. , Sterling R. , Frey H. U. , Harris S. E. , McBride S. , Rosenberg T. J. , Detrick D. , Doolittle J. L. , Engebretson M. , Inan U. , Labelle J. W. , Lanzerotti L. J. , Weatherwax A. T.
Published: December 2009

Coupling of the solar wind to the Earth magnetosphere/ionosphere is primarily through the high latitude regions, and there are distinct advantages in making remote sensing observations of these regions with a network of ground-based observatories over other techniques. The Antarctic continent is ideally situated for such a network, especially for optical studies, because the larger offset between geographic and geomagnetic poles in the south enables optical observations at a larger range of magnetic latitudes during the winter darkness. The greatest challenge for such ground-based observations is the generation of power and heat for a sizable ground station that can accommodate an optical imaging instrument. Under the sponsorship of the National Science Foundation, we have developed suitable automatic observing platforms, the Automatic Geophysical Observatories (AGOs) for a network of six autonomous stations on the Antarctic plateau. Each station housed a suite of science instruments including a dual wavelength intensified all-sky camera that records the auroral activity, an imaging riometer, fluxgate and search-coil magnetometers, and ELF/VLF and LM/MF/HF receivers. Originally these stations were powered by propane fuelled thermoelectric generators with the fuel delivered to the site each Antarctic summer. A by-product of this power generation was a large amount of useful heat, which was applied to maintain the operating temperature of the electronics in the stations. Although a reasonable degree of reliability was achieved with these stations, the high cost of the fuel air lift and some remaining technical issues necessitated the development of a different type of power unit. In the second phase of the project we have developed a power generation system using renewable energy that can operate automatically in the Antarctic winter. The most reliable power system consists of a type of wind turbine using a simple permanent magnet rotor and a new type of power control system with variable resistor shunts to regulate the power and dissipate the excess energy and at the same time provide heat for a temperature controlled environment for the instrument electronics and data system. We deployed such systems and demonstrated a high degree of reliability in several years of operation in spite of the relative unpredictability of the Antarctic environment. Sample data are shown to demonstrate that the AGOs provide key measurements, which would be impossible without the special technology developed for this type of observing platform.
Pressure-energy correlations in liquids. IV. “Isomorphs” in liquid phase diagrams
Authors: Gnan Nicoletta , Schrøder Thomas B. , Pedersen Ulf R. , Bailey Nicholas P. , Dyre Jeppe C.
Published: December 2009

This paper is the fourth in a series devoted to identifying and explaining the properties of strongly correlating liquids, i.e., liquids where virial and potential energy correlate better than 90% in their thermal equilibrium fluctuations in the NVT ensemble. For such liquids we here introduce the concept of “isomorphic” curves in the phase diagram. A number of thermodynamic, static, and dynamic isomorph invariants are identified. These include the excess entropy, the isochoric specific heat, reduced-unit static and dynamic correlation functions, as well as reduced-unit transport coefficients. The dynamic invariants apply for both Newtonian and Brownian dynamics. It is shown that after a jump between isomorphic state points the system is instantaneously in thermal equilibrium; consequences of this for generic aging experiments are discussed. Selected isomorph predictions are validated by computer simulations of the Kob–Andersen binary Lennard-Jones mixture, which is a strongly correlating liquid. The final section of the paper relates the isomorph concept to phenomenological melting rules, Rosenfeld’s excess entropy scaling, Young and Andersen’s approximate scaling principle, and the two-order parameter maps of Debenedetti and co-workers. This section also shows how the existence of isomorphs implies an “isomorph filter” for theories for the non-Arrhenius temperature dependence of viscous liquids’ relaxation time, and it explains isochronal superposition for strongly correlating viscous liquids.
Effect of hydrogen on nanoindentation-induced phase transformations in amorphous silicon
Authors: Ruffell S. , Vedi J. , Bradby J. E. , Williams J. S.
Published: December 2009

The effect of local hydrogen concentration on nanoindentation-induced phase transformations has been investigated in ion-implanted amorphous silicon (a-Si). Elevated concentrations of H ranging from 5×1018 to 5×1020 cm−3, over the depth of indentation-induced phase transformed zones have been formed in the a-Si by H ion-implantation. Indentation has been performed under conditions that result in phase transformed zones composed totally of Si-III/Si-XII in the “H-free” samples. Deformation during indentation and determination of phase transformation behavior has been examined by analysis of load/unload curves, Raman microspectroscopy, and cross-sectional transmission electron microscopy (XTEM). With increasing H content, the probability of forming Si-III/Si-XII and the volume fraction of Si-III/Si-XII decrease. XTEM shows that these reduced volumes are randomly distributed within the phase transformed zone and are surrounded by indentation-induced a-Si. For a H concentration of 5×1020 cm−3, the probability of forming Si-III/Si-XII is reduced to 0.5 compared to 1 in “H-free” material and for those indents that exhibit the Si-III/Si-XII end phase the volume fraction is approximately 60 %. We suggest that the monohydride bonding configuration of Si and H in a-Si reduces the formation of the high pressure crystalline phases by retarding growth of the crystallites through a similar mechanism to that of hydrogen-retarded solid phase crystallization of a-Si to diamond cubic crystalline Si-I phase.
Impact of base size and shape on formation control of multifaceted InP nanopyramids by selective area metal organic vapor phase epitaxy
Authors: Yuan Jiayue , Wang Hao , van Veldhoven Peter J. , Nötzel Richard
Published: December 2009

We report the impact of base size and shape on the evolution control of multifaceted InP (100) nanopyramids grown by selective area metal organic vapor phase epitaxy. The pyramid top surfaces are composed of a (100) center facet surrounded by high-index {103} and {115} facets. Their arrangement and (relative) size depend on the size and shape of the pyramid top area. For a certain shape, only the (100) facet remains below a critical size of the top area. The arrangement and (relative) size of the top facets in turn are governed by the {110} and {111} side facets whose area (ratio) depends on the pyramid base size and shape. This self-consistently determines the ratio of the (100) top facet area and the sum of the {110} and {111} side facet areas as well as the height of the pyramids.
Enhanced tetragonality in lead-free piezoelectric (1−x)BaTiO3–xNa1∕2Bi1∕2TiO3 solid solutions where x=0.05–0.40
Authors: Datta K. , Roleder K. , Thomas P. A.
Published: December 2009

A structural investigation was carried out on a perovskite-based solid solution of xNa1∕2Bi1∕2TiO3–(1−x)BaTiO3, where x⩽0.40. The crystal structure remains tetragonal, P4mm, for these compositions; however, enhancement of the tetragonality up to 0.9% of the unit cell was observed as a function of doping which is an unusual phenomenon in BaTiO3 based binary solid solutions. Crystallographic details of the structural changes that have occurred because of the doping were obtained by performing Rietveld refinement on neutron powder diffraction data collected at HRPD of the ISIS spallation neutron source. Temperature- and frequency-dependent dielectric data as a function of composition are presented to understand the structure-property relationships in this novel system.
Raman scattering study of zinc blende and wurtzite ZnS
Authors: Cheng Y. C. , Jin C. Q. , Gao F. , Wu X. L. , Zhong W. , Li S. H. , Chu Paul K.
Published: December 2009

We have conducted an experimental and theoretical study on first- and second-order Raman scattering of zinc blende and wurtzite ZnS. Based on the calculated phonon band structure, phonon density of states, and symmetry selection rules, we have clearly identified for the first time the origins of these vibration modes in the second-order Raman spectra from these two polymorphs. For zinc blende ZnS, it is found that the previously estimated frequency of the LA mode at X point in the Brillouin-zone boundary is much smaller than the value obtained from other experiments and our calculation. Considering the involvement of LA phonon at X point, we reassign the second-order Raman active modes and some other modes which have not yet been understood so far. This work clarifies some of the controversial Raman mode assignments in zinc blende and wurtzite ZnS.
Extensive regularization of the coupled cluster methods based on the generating functional formalism: Application to gas-phase benchmarks and to the SN2 reaction of CHCl3 and OH− in water
Authors: Kowalski Karol , Valiev Marat
Published: December 2009

The recently introduced energy expansion based on the use of generating functional (GF) [K. Kowalski and P. D. Fan, J. Chem. Phys. 130, 084112 (2009)] provides a way of constructing size-consistent noniterative coupled cluster (CC) corrections in terms of moments of the CC equations. To take advantage of this expansion in a strongly interacting regime, the regularization of the cluster amplitudes is required in order to counteract the effect of excessive growth of the norm of the CC wave function. Although proven to be efficient, the previously discussed form of the regularization does not lead to rigorously size-consistent corrections. In this paper we address the issue of size-consistent regularization of the GF expansion by redefining the equations for the cluster amplitudes. The performance and basic features of proposed methodology are illustrated on several gas-phase benchmark systems. Moreover, the regularized GF approaches are combined with quantum mechanical molecular mechanics module and applied to describe the SN2 reaction of CHCl3 and OH− in aqueous solution.
Enhancement of magnetoelectric coupling in a piezoelectric-magnetostrictive semiring structure
Authors: Zhang N. , Petrov V. M. , Johnson T. , Mandal S. K. , Srinivasan G.
Published: December 2009

Studies on magnetoelectric (ME) coupling in a semiring of lead zirconate titanate (PZT) with a Terfenol-D insert reveal strong ME coupling at low frequencies and two orders of magnitude enhancement in the strength at resonance associated with a unique bending mode in PZT. A model is discussed for the resonance ME coupling that arises from radial and shearing displacements and theoretical estimates are in excellent agreement with the data. The model also predicts weak ME coupling in a full ring of PZT with Terfenol-D insert in agreement with the experiment. The results are of importance for ME composite based magnetic field sensors.
Thermal modeling and experimental study of infrared nanosecond laser ablation of silicon
Authors: Tao Sha , Wu Benxin , Zhou Yun , Gao Yibo
Published: December 2009

Nanosecond (ns) laser ablation of silicon has important applications in electronics, photovoltaics, and many other areas. However, most of the previous work is mainly focused on ultraviolet (UV) or visible ns lasers, and the investigation is very limited for infrared lasers (e.g., at 1064 nm), which have the advantage of much lower cost and external energy consumption. In this paper, a thermal model has been developed and experimentally verified for ablation of silicon by 200 ns and 1064 nm laser pulses. This kind of work has been rarely reported in literature. The model predictions agree reasonably well with experimental measurements. The investigation indicates that surface evaporation should be the dominant physical mechanism of material removal for laser silicon ablation under the studied conditions. It has also been found that the physical processes of multipulse laser-silicon interaction at 1064 nm may strongly depend on laser pulse number and repetition rate (the pulse-to-pulse temporal distance).
MnSe phase segregation during heteroepitaxy of Mn doped Ga2Se3 on Si(001)
Authors: Lovejoy T. C. , Yitamben E. N. , Heald S. M. , Ohuchi F. S. , Olmstead M. A.
Published: December 2009

Heteroepitaxial thin films of Mn-doped Ga2Se3 are grown by molecular beam epitaxy on Si(001):As. Mn-doped films are laminar for the first 1–2 nm, after which oriented islands with flat tops are observed by scanning tunneling microscopy. In contrast with the bulk phase diagram, which predicts MnGa2Se4 precipitates, the precipitates are identified by bond length measurements from extended x-ray absorption fine structure as rocksalt MnSe. This difference is attributed to superior lattice matching of MnSe to the substrate, and an epitaxial relationship between the MnSe and Si substrate is inferred.
Nonlinear diffusion in two-dimensional ordered porous media based on a free volume theory
Authors: Godec A. , Gaberscek M. , Jamnik J. , Merzel F.
Published: December 2009

A continuum nonlinear diffusion model is developed to describe molecular transport in ordered porous media. An existing generic van der Waals equation of state based free volume theory of binary diffusion coefficients is modified and introduced into the two-dimensional diffusion equation. The resulting diffusion equation is solved numerically with the alternating-direction fully implicit method under Neumann boundary conditions. Two types of pore structure symmetries are considered, hexagonal and cubic. The former is modeled as parallel channels while in case of the latter equal-sized channels are placed perpendicularly thus creating an interconnected network. First, general features of transport in both systems are explored, followed by the analysis of the impact of molecular properties on diffusion inside and out of the porous matrix. The influence of pore size on the diffusion-controlled release kinetics is assessed and the findings used to comment recent experimental studies of drug release profiles from ordered mesoporous silicates.