bluuebunny/crossref_metadata_2025_split huggingface dataset:
Piezoelectric properties of zinc blende quantum dots
Authors: Schulz S. , Caro M. A. , O'Reilly E. P. , Marquardt O. 
Published: January 2012

AbstractPiezoelectric coefficients of zinc blende (ZB) InN, GaN, and AlN have been estimated from the piezoelectric coefficients of the wurtzite (WZ) system. This procedure is based on a rotation of the first‐order piezoelectric tensor of a (001)‐oriented ZB structure to a (111)‐oriented ZB structure, which is similar to a WZ structure. The derived expressions for the piezoelectric coefficients in a (111)‐oriented ZB system are benchmarked against literature coefficients of different WZ materials, showing a very good agreement. To perform the desired opposite operation, a least square fitting procedure was used to find the ZB piezoelectric coefficient e14 that provides the closest reverse transformation to the known WZ constants. Using e14, the piezoelectric potential in a GaN/AlN QD is calculated and compared to a InAs/GaAs QD, revealing a much larger potential in the nitride system, even though the lattice mismatch is much smaller in this system. The result is related to the large piezoelectric coefficient e14 in ZB nitride materials.
Lateral charge carrier diffusion in InGaN quantum wells
Authors: Danhof J. , Solowan H.‐M. , Schwarz U. T. , Kaneta A. , Kawakami Y. , Schiavon D. , Meyer T. , Peter M. 
Published: January 2012

AbstractWe investigated lateral charge carrier transport in indium gallium nitride InGaN/GaN multi‐quantum wells for two different samples, one sample emitting green light at about 510 nm and the other emitting cyan light at about 470 nm. For the cyan light emitting sample we found a diffusion constant of 1.2 cm2/s and for the green light emitting sample 0.25 cm2/s. The large difference in diffusion constant is due to a higher point defect density in the green light emitting quantum wells (QWs) as high indium incorporation tends to reduce material quality.
Molecular and electronic structures of endohedral fullerenes, Sc2C2@C3v–C82 and Sc2@C3v–C82: Benchmark for SCC‐DFTB and proposal of new inner cluster structures
Authors: Nishimoto Yoshio , Wang Zhi , Morokuma Keiji , Irle Stephan 
Published: January 2012

AbstractThe molecular and electronic structures of Sc2C2@C3v–C82 and Sc2@C3v–C82 were investigated by means of conventional density functional theory (DFT) and the self‐consistent‐charge density‐functional tight‐binding (SCC‐DFTB, short: “DFTB”) method. In the DFT calculations, three functionals were adopted: BP86, B3LYP, and PBE. We find that it is necessary to employ tight geometry convergence criteria, which will lead to a reduction of the number of unique isomers. Generally, the DFTB method shows good agreement on relative energies, inner cluster binding energies (BE), and geometries with those predicted by the DFT calculations. In optimized structures, we found that some fullerene cages contain a more linear Sc–CC–Sc inner cluster that are more stable than those containing the butterfly‐shaped cluster that was reported before. We found that DFTB overestimates Sc–Sc binding in the case of Sc2@C82 isomers, which became also evident in a comparison of molecular orbital (MO) correlation diagrams between PBE and DFTB methods. It is concluded that DFTB with the present parameters can be reliably employed for fullerene systems consisting of C and Sc atoms without direct Sc–Sc bonding.magnified image
PAL signature of physical ageing in chalcogenide glasses
Authors: Ingram Adam , Kozdras Andrzej , Shpotyuk Oleh , Golovchak Roman 
Published: January 2012

AbstractKinetics of physical ageing (PhA) far below the glass transition temperature (Tg) is studied by positron annihilation lifetime and differential scanning calorimetry techniques for vitreous As20Se80 as typical representative of network glasses. The increased density fluctuations are shown to be responsible for the initial stage of PhA in this glass at below‐Tg temperatures. These fluctuations are correlated with changes in thermodynamic parameters of structural relaxation through the glass‐to‐supercooled liquid transition interval. General shrinkage, occurred during the next stage of PhA, is shown to be determined by the ability of system to release these redundant open volumes from the glass bulk through densification process of glass network.
Turbulence in the nocturnal boundary layer with light and variable winds
Authors: Mahrt L. , Richardson Scott , Seaman Nelson , Stauffer David 
Published: January 2012

AbstractTurbulence quantities are analyzed from nine months of data collected on the floor of a valley where nocturnal cold pools are frequent. Often the speed of the vector‐averaged wind over the night is less than 0.5 m s−1 (near‐calm winds) with no preference for wind direction. The quantity of such near‐calm data is sufficiently large to allow new types of analyses as well as the opportunity to examine statistics of the previously ignored near‐neutral subclass of near‐calm winds.For near‐calm weak winds and strong stratification, the turbulence can be difficult to isolate from wave‐like motions and more complex small‐scale structures. The smallest scale perturbations on time‐scales less than 5 s behave most like turbulence. Larger‐scale perturbations are characterized by very weak vertical velocity fluctuations and large temperature fluctuations, but lead to systematic downward heat flux after extensive averaging.For near‐calm nocturnal conditions, significant turbulence is mainly generated by short‐term (minutes) accelerations of unknown origin. The turbulence between such infrequent mixing events is extremely weak, but not zero. While the turbulence in the events approximately follows similarity theory, the extremely weak turbulence scales neither with stratification nor bulk shear, and its inferred vertical length‐scale is small compared to the distance from the ground, even at the 2 m level. Copyright © 2012 Royal Meteorological Society
Self‐supervised terrain classification for planetary surface exploration rovers
Authors: Brooks Christopher A. , Iagnemma Karl 
Published: January 2012

AbstractIn future planetary exploration missions, improvements in autonomous rover mobility have the potential to increase scientific data return by providing safe access to geologically interesting sites that lie in rugged terrain, far from landing areas. To improve rover‐based terrain sensing, this paper proposes a self‐supervised learning framework that will enable a robotic system to learn to predict mechanical properties of distant terrain, based on measurements of mechanical properties of similar terrain that has been traversed previously. In this framework, a proprioceptive terrain classifier is used to distinguish terrain classes based on features derived from rover–terrain interaction, and labels from this classifier are used to train an exteroceptive (i.e., vision‐based) terrain classifier. Once trained, the vision‐based classifier is able to recognize similar terrain classes in stereo imagery. This paper presents two distinct proprioceptive classifiers—a novel approach based on optimization of a traction force model and a previously described approach based on wheel vibration—as well as a vision‐based terrain classification approach suitable for environments with unexpected appearances. The high accuracy of the self‐supervised learning framework and its supporting algorithms is demonstrated using experimental data from a four‐wheeled robot in an outdoor Mars‐analogue environment. © 2012 Wiley Periodicals, Inc.
Investigations of molecular depth profiling with dual beam sputtering
Authors: Lu C. , Wucher A. , Winograd N. 
Published: January 2012

ABSTRACTIn this study, the feasibility of molecular depth profiling using dual beam sputtering of biological materials is examined. The model system is a 402‐nm Langmuir Blodgett multilayer film consisting of 149 monolayers of barium arachidate (AA). The thin film was initially subjected to pre‐bombardment with a 15‐keV Au+ beam. Subsequently, an imaging depth profile experiment was performed on the pre‐irradiated sample using a 40‐keV C60+ beam. An extremely low erosion rate under Au+ bombardment is found on this model system. In the subsequent C60+ depth profiles, surprisingly large molecular ion signals are detected at the gold pre‐irradiated surface. These signals then rapidly decay to nearly zero, indicating a damaged sub‐surface layer being generated by the Au+ pre‐bombardment. The thickness of the damaged layer is found to increase with increasing gold ion fluence and saturate at about 100 nm at 6 × 1014 Au+/cm2. This altered layer thickness is significantly larger than the value of ~50 nm obtained on a trehalose film pre‐bombarded with a Ga+ source. The results also show that the damage caused by the Au+ beam can be removed by C60+ sputtering and that the molecular information is restored after damage removal. Copyright © 2012 John Wiley & Sons, Ltd.
Pediatric Non‐Wilms’ Renal Tumors: A Third World Experience
Authors: Saula Peter W. , Hadley G. P. 
Published: January 2012

AbstractBackgroundPediatric non‐Wilms’ renal tumors (NWRT) are poorly understood owing to their heterogeneity and relative rarity. This study aimed at auditing the outcome of the management of NWRT in a tertiary hospital in the Third World.MethodsRecords of all patients (n = 68) treated for NWRT over a 32‐year period (1978–2010) were reviewed retrospectively.ResultsThe major histological groups included clear cell sarcoma of the kidney (CCSK) (33.8%), mesoblastic nephroma (17.6%), cystic partially differentiated nephroblastoma (CPDN) (17.6%), intrarenal neuroblastoma (8.8%), malignant rhabdoid tumor (MRT) (7.4%), and renal cell carcinoma (RCC) (5.9%). Sixteen (69.7%) patients with CCSK and 11 (91.7%) with CPDN were aged 1–4 years. Ten (83.3%) patients with mesoblastic nephroma were aged <1 year and three (60.0%) with RCC were aged 10–14 years. Ten (43.5%) patients with CCSK and four (80.0%) with RCC had metastases at diagnosis. The sensitivity of a pretreatment Tru‐Cut biopsy was 100% for MRT. All the patients with CCSK, mesoblastic nephroma, CPDN, and RCC had radical nephrectomy. Only eight (34.8%) patients with CCSK received radiotherapy. The overall 1–10‐year survival rates were 52.2%, 91.7%, 75.0%, 40.0% and 0.0% for CCSK, mesoblastic nephroma, CPDN, RCC, and MRT, respectively. The overall 1–10‐year survival for the entire cohort was 51.5%.ConclusionsThe demography and clinical presentation of pediatric NWRT, which comprises 13.6% of pediatric renal tumors in the Third World, were similar to those in the Developed World. The overall 1–10‐year survival for pediatric NWRT was low.
Kinetics of sugars consumption and ethanol inhibition in carob pulp fermentation by Saccharomyces cerevisiae in batch and fed-batch cultures
Authors: Lima-Costa Maria Emília , Tavares Catarina , Raposo Sara , Rodrigues Brígida , Peinado José M 
Published: January 2012

Abstract
The waste materials from the carob processing industry are a potential resource for second-generation bioethanol production. These by-products are small carob kibbles with a high content of soluble sugars (45–50%). Batch and fed-batch Saccharomyces cerevisiae fermentations of high density sugar from carob pods were analyzed in terms of the kinetics of sugars consumption and ethanol inhibition. In all the batch runs, 90–95% of the total sugar was consumed and transformed into ethanol with a yield close to the theoretical maximum (0.47–0.50 g/g), and a final ethanol concentration of 100–110 g/l. In fed-batch runs, fresh carob extract was added when glucose had been consumed. This addition and the subsequent decrease of ethanol concentrations by dilution increased the final ethanol production up to 130 g/l. It seems that invertase activity and yeast tolerance to ethanol are the main factors to be controlled in carob fermentations. The efficiency of highly concentrated carob fermentation makes it a very promising process for use in a second-generation ethanol biorefinery.
Patterns of species diversity and soil nutrients along a chronosequence of vegetation recovery in Hainan Island, South China
Authors: Long Wenxing , Yang Xiaobo , Li Donghai 
Published: January 2012

AbstractUnderstanding the pattern of species diversity and soil factors can enhance our knowledge of the mechanism of vegetation recovery, however, there is still a gap in the knowledge of succession rate and trend for species diversity in relation to soil nutrients during the vegetation recovery process. Patterns of species diversity and soil nutrients during the tropical vegetation recovery as well as the correlation between species diversity and soil nutrients were explored in Hainan Island, located in southern China. Plots assigned as grassland stage (GS), shrub stage (SS), secondary forest stage (SFS), and primary forest stage (PFS) were established using a chronosequence approach. Results showed that species richness and evenness increased from GS to PFS. Species dominance/diversity curves were fitted using the lognormal distribution model (r2= 0.891–0.972). Species richness for the herb layer was maximal at SFS, whereas species richness for both the shrub layer and tree layer reached their maximum at PFS. Species turnover and soil total phosphorus decreased, whereas organic matter and total nitrogen increased from GS to PFS. Organic matter and total nitrogen were both positively correlated with species richness and total coverage, and total phosphorus was positively correlated with species turnover. The results clearly demonstrate that diversity asymptotically increases and positively correlates with increasing soil fertility, and the total phosphorus value is predicted to be an important soil factor that affects successional rate during tropical vegetation recovery processes.
Corticosteroid Injection for Carpal Tunnel Syndrome: A 5-Year Survivorship Analysis
Authors: Jenkins Paul J. , Duckworth Andrew D. , Watts Adam C. , McEachan Jane E. 
Published: January 2012

Background The purpose of our study was to determine the rate of carpal tunnel decompression (CTD) following local corticosteroid injection for carpal tunnel syndrome (CTS), as well as identifying predictors of requiring further intervention and eventual decompression. Methods All patients diagnosed with CTS in our unit over a 6-year period were prospectively assessed. Patients were diagnosed using a combination of clinical presentation and nerve conduction studies. Patients were managed with open carpal tunnel decompression or corticosteroid injection. There were 1,564 consecutive patients diagnosed with CTS over the study period, of whom 824 (53%) underwent a corticosteroid injection as their primary treatment. We performed a survivorship analysis of these patients and used Kaplan–Meier survivorship methodology to determine the 5-year rate of re-intervention. Risk factors for re-intervention were also determined. Results The overall 5-year Kaplan–Meier rate of secondary CTD was 15% at 1 year and 33% at 5 years. The need for secondary CTD was independently associated with female gender, diabetes mellitus and positive nerve conduction studies at diagnosis. Conclusions Steroid injection is an appropriate treatment in carefully selected patients. Those who are female, diabetic and have neurophysiological confirmation of diagnosis have the highest risk of relapse. These results may be used to guide initial treatment and counsel patients about the risk relapse.
Severity of fatty liver on ultrasound correlates with metabolic and cardiovascular risk
Authors: Wang Chia‐Chi , Tseng Tai‐Chung , Hsieh Tsung‐Cheng , Hsu Ching‐Sheng , Wang Pin‐Chao , Lin Hans Hsienhong , Kao Jia‐Horng 
Published: January 2012

AbstractNon‐alcoholic fatty liver disease is associated with an increased risk of metabolic and cardiovascular diseases. Whether the severity of fatty liver on ultrasound correlates with metabolic or cardiovascular risk remains unclear. A total of 1000 people receiving health examinations were enrolled, and 126 were excluded due to the presence of HBsAg, anti‐HCV, known hepatic disorders or alcohol use (>140 g/wk). Significant fatty liver consisted of moderate and severe fatty liver on ultrasound. The definition of central obesity was modified to a waist circumference of >90 cm in men and >80 cm in women. Framingham risk score was used to estimate the risk of cardiovascular disease. A total of 874 subjects (485 women and 388 men with a mean age of 52.07 ± 11.68 years) were included in the final analysis. By using logistic regression analyses stratified by gender, the odds ratio for the prevalence of diabetes mellitus, metabolic syndrome and risk of cardiovascular disease increased with increasing fatty liver status in both genders (p ≤ 0.001). The difference was not only present between individuals with fatty liver vs. non‐fatty liver but also between the mild fatty liver and significant fatty liver groups (p < 0.05). In conclusion, the severity of fatty liver on ultrasound could be useful for the risk stratification of metabolic syndrome, diabetes mellitus and cardiovascular disease in clinical practice.
THE JANUS FACE OF INSURANCE IN SOUTH AFRICA: FROM COSTS TO RISK, FROM NETWORKS TO BUREAUCRACIES
Authors: Bähre Erik 
Published: January 2012

ABSTRACTThis study examines the consequences of the rapid and unprecedented expansion of insurances for the poor in South Africa. Over the last ten years, South African insurance companies established a myriad of policies in order to incorporate the previously excluded, mostly African, poor and lower middle classes. While poverty, violence and AIDS put state institutions and social relations under pressure, insurances enable people to manage risks in hitherto unthinkable ways. The article examines the development of this new regime of risk as a Janus head, after the Roman god of opening and closing. At the heart of access to insurance were the incongruencies that were caused by the ‘translation’ of risk into the seemingly neutral concept of costs and the inability of brokers and intermediary organizations to navigate these translations successfully. Access to insurance – here not defined as having an insurance policy but as making a successful claim when confronted with the insured risk – was fraught with the contradictions of complex high-tech bureaucracies and the poor's social networks.
Ultrasound-guided core-needle biopsy and magnetic resonance imaging in the accurate diagnosis of intramuscular haemangiomas of the head and neck
Authors: Salzman R , Buchanan M A , Berman L , Jani P 
Published: January 2012

AbstractIntroduction:Intramuscular haemangiomas of the digastric muscle are often misdiagnosed due to their low incidence and non-specific manifestation. Only two out of six previously reported cases were diagnosed correctly before excision. Ultrasound may not reveal their vascularity, and fine-needle aspiration biopsy is unhelpful as it reveals only blood.Methods:A case of intramuscular haemangioma of the posterior belly of the digastric muscle is described. Previously reported cases are reviewed. Investigations used to diagnose the lesions and reasons for their common failure are discussed.Results:Core-needle biopsy led to the correct histological diagnosis, and magnetic resonance imaging precisely located the lesion within the digastric muscle.Conclusion:Core-needle biopsy was safely used in the diagnosis of an intramuscular haemangioma. The combination of core-needle biopsy and meticulous review of magnetic resonance imaging enables accurate diagnosis pre-operatively.
Structural Remodeling and Mechanical Function in Heart Failure
Authors: Leonard Bridget Louise , Smaill Bruce Henry , LeGrice Ian John 
Published: January 2012

AbstractThe cardiac extracellular matrix (ECM) is the three-dimensional scaffold that defines the geometry and muscular architecture of the cardiac chambers and transmits forces produced during the cardiac cycle throughout the heart wall. The cardiac ECM is an active system that responds to the stresses to which it is exposed and in the normal heart is adapted to facilitate efficient mechanical function. There are marked differences in the short- and medium-term changes in ventricular geometry and cardiac ECM that occur as a result of volume overload, hypertension, and ischemic cardiomyopathy. Despite this, there is a widespread view that a common remodeling “phenotype” governs the final progression to end-stage heart failure in different forms of heart disease. In this review article, we make the case that this interpretation is not consistent with the clinical and experimental data on the topic. We argue that there is a need for new theoretical and experimental models that will enable stresses acting on the ECM and resultant deformations to be estimated more accurately and provide better spatial resolution of local signaling mechanisms that are activated as a result. These developments are necessary to link the effects of structural remodeling with altered cardiac mechanical function.
Dynamic Task Selection in Learning Arithmetic: The Role of Learner Control and Adaptation Based on a Hierarchy of Skills 1Dieser Beitrag wurde unter der geschäftsführenden Herausgeberschaft von Jens Möller angenommen
Authors: Schoppek Wolfgang 
Published: January 2012

Abstract.The effects of locus of instructional control in computer-assisted practice of arithmetic skills and word problem solving were investigated in a field experiment with 13 third grade classes. In a program-controlled condition (n = 95), the selection of practice problems was based on a hypothetical hierarchy of skills. This was expected to regulate cognitive load to a moderate level. In a condition with shared control (n = 89), subjects could select problems from a subset provided by the program. Results show that program-controlled selection of problems based on the hierarchy of skills was more successful in supporting skill development than the students’ selection. In the shared control condition, students tended to select too easy problems, regardless of their level of expertise. Both conditions with computer assisted instruction caused more progress than traditional instruction (n = 94). Ways of improving the regulation of cognitive load within a shared control approach are discussed.
Variation in local carrying capacity and the individual fate of bacterial colonizers in the phyllosphere
Authors: Remus-Emsermann Mitja N P , Tecon Robin , Kowalchuk George A , Leveau Johan H J 
Published: January 2012

Abstract
Using a phyllosphere model system, we demonstrated that the term ‘carrying capacity’, as it is commonly used in microbial ecology, needs to be understood as the sum of many ‘local carrying capacities’ in order to better explain and predict the course and outcome of bacterial colonization of an environment. Using a green fluorescent protein-based bioreporter system for the quantification of reproductive success (RS) in individual Erwinia herbicola cells, we were able to reconstruct the contribution of individual immigrants to bacterial population sizes on leaves. Our analysis revealed that plant foliage represents to bacteria an environment where individual fate is determined by the local carrying capacity of the site where an immigrant cell lands. With increasing inoculation densities, the RS of most immigrants declined, suggesting that local carrying capacity under the tested conditions was linked to local nutrient availability. Fitting the observed experimental data to an adapted model of phyllosphere colonization indicated that there might exist three types of sites on leaves, which differ in their frequency of occurrence and local carrying capacity. Specifically, our data were consistent with a leaf environment that is characterized by few sites where individual immigrants can produce high numbers of offspring, whereas the remainder of the leaf offered an equal number of sites with low and medium RS. Our findings contribute to a bottom–up understanding of bacterial colonization of leaf surfaces, which includes a quantifiable role of chance in the experience at the individual level and in the outcome at the population level.