bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of glycosylation in structure and stability of Erythrina corallodendron lectin (EcorL): A molecular dynamics study
Authors: Kaushik Sandeep , Mohanty Debasisa , Surolia Avadhesha
Published: December 2010

The effect of glycosylation on structure and stability of glycoproteins has been a topic of considerable interest. In this work, we have investigated the solution conformation of the oligosaccharide and its effect on the structure and stability of the glycoprotein by carrying out a series of long Molecular dynamics (MD) simulations on glycosylated Erythrina corallodendron lectin (EcorL) and nonglycosylated recombinant Erythrina corallodendron lectin (rEcorL). Our results indicate that, despite the similarity in overall three dimensional structures, glycosylated EcorL has lesser nonpolar solvent accessible surface area compared to nonglycosylated EcorL. This might explain the experimental observation of higher thermodynamic stability for glycosylated EcorL compared to nonglycosylated EcorL. Analysis of the simulation results indicates that, dynamic view of interactions between protein residues and oligosaccharide is entirely different from the static picture seen in the crystal structure. The oligosaccharide moiety had dynamically stable interactions with Lys 55 and Tyr 53, both of which are separated in sequence from the site of glycosylation, Asn 17. It is possible that glycosylation helps in forming long‐range contacts between amino acids, which are separated in sequence and thus provides a folding nucleus. Thus our simulations not only reveal the conformations sampled by the oligosaccharide, but also provide novel insights into possible molecular mechanisms by which glycosylation can help in folding of the glycoprotein by formation of folding nucleus involving specific contacts with the oligosaccharide moiety.
The accuracy of the standard resistivity–concentration conversion practice estimated by measuring the segregation coefficient of boron and phosphorous in Cz‐Si
Authors: Giannattasio Armando , Giaquinta Andrea , Porrini Maria
Published: December 2010

The effective segregation coefficient of boron and phosphorous has been extrapolated from resistivity data collected for a large number of commercial Cz‐Si crystals, pulled in similar experimental conditions. A small solidified fraction of the Si melt volume and different initial concentrations of the doping species in the melt have been considered in this study. The dopant concentration in the solid phase has been estimated by converting the resistivity of the Si crystal to the corresponding dopant concentration, according to the standard conversion practice recommended by SEMI. A dependence of the effective segregation coefficient on the initial dopant concentration in the melt has been found experimentally for two specific ranges of concentration. A possible explanation for such dependence, including the effect of the crucible dissolution and the local inaccuracy of the standard resistivity–concentration conversion procedure, is suggested.
Adding a thin metallic plasmonic layer to silicon thin film solar cells
Authors: Lu Yalin , Sell J. F. , Johnson M. D. , Reinhardt K. , Knize R. J.
Published: December 2010

Currently, thin film solar cells' performances are limited by poor light absorption and poor photon‐generated carrier collection. Theoretically, large, broadband, and polarization‐insensitive light absorption enhancement can be realized via integrating with unique metallic nanostructures either at the surface or buried inside the structures. In order further to understand the mechanisms and to reduce the fabrication cost, an experimental demonstration of light absorption affection by adding a thin metallic plasmonic layer to the thin film a‐Si solar cells was performed. By adjusting those structural parameters such as thicknesses of the a‐Si thin layer and the thin plasmonic layer's thickness, and the incident angle, light absorption enhancement by cavity resonances and by the planar plasmonic coupling was carefully analyzed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dopant activation and damage evolution in implanted silicon after excimer laser annealing
Authors: Fisicaro G. , Italia M. , Privitera V. , Piccitto G. , Huet K. , Venturini J. , La Magna A.
Published: December 2010

The relationship between dopant activation and damage evolution in implanted silicon after multi‐pulsed laser thermal annealing process is investigated by means of simulations and experimental analysis. The code simulates the dopant evolution coupled to the defect kinetics in the presence of fast varying temperature, high thermal gradients and phase transition. It considers defects (interstitials Is and vacancies Vs) clustering, annihilation and the interaction between point defects and the active/inactive fractions of the impurity density. Simulations allow a characterization of the residual damage as a function of the process conditions. Moreover, the model correctly predicts some experimental P profiles. Among the studied irradiation conditions, the partial melting regime shows an interesting dynamics of the active profile fraction as a function of laser energy and the pulse number. Finally, simulations also demonstrate that the status of the defect system rules the activation phenomenon, which can be reliably predicted only including in the model the defect‐(active)impurity coupling (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Highly strained Si epilayers grown on SiGe/Si(100) virtual substrate by reduced pressure chemical vapour deposition
Authors: Myronov M. , Shah V. A. , Dobbie A. , Liu Xue‐Chao , Nguyen Van H. , Leadley D. R. , Parker E. H. C.
Published: December 2010

Bi‐axial tensile strained Si epilayers with extremely high lattice mismatch strain up to 2.13% were grown from a disilane (Si2H6) precursor on Si1‐xGex/Si(100) VSs by Reduced Pressure Chemical Vapour Deposition. We discuss the conditions under which fully strained Si epilayers of the required thickness can be grown. By demonstrating a fully strained 23 nm Si layer on a fully relaxed Si0.45Ge0.55(100) VS, this work indicates the potential for realizing high performance s‐Si n‐ and p‐MOSFETs on standard Si(100) substrates. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Discriminant analysis using a multivariate linear mixed model with a normal mixture in the random effects distribution
Authors: Komárek Arnošt , Hansen Bettina E. , Kuiper Edith M. M. , van Buuren Henk R. , Lesaffre Emmanuel
Published: December 2010

We have developed a method to longitudinally classify subjects into two or more prognostic groups using longitudinally observed values of markers related to the prognosis. We assume the availability of a training data set where the subjects' allocation into the prognostic group is known. The proposed method proceeds in two steps as described earlier in the literature. First, multivariate linear mixed models are fitted in each prognostic group from the training data set to model the dependence of markers on time and on possibly other covariates. Second, fitted mixed models are used to develop a discrimination rule for future subjects. Our method improves upon existing approaches by relaxing the normality assumption of random effects in the underlying mixed models. Namely, we assume a heteroscedastic multivariate normal mixture for random effects. Inference is performed in the Bayesian framework using the Markov chain Monte Carlo methodology. Software has been written for the proposed method and it is freely available. The methodology is applied to data from the Dutch Primary Biliary Cirrhosis Study. Copyright © 2010 John Wiley & Sons, Ltd.
Hurdle models for multilevel zero‐inflated data via h‐likelihood
Authors: Molas Marek , Lesaffre Emmanuel
Published: December 2010

Count data often exhibit overdispersion. One type of overdispersion arises when there is an excess of zeros in comparison with the standard Poisson distribution. Zero‐inflated Poisson and hurdle models have been proposed to perform a valid likelihood‐based analysis to account for the surplus of zeros. Further, data often arise in clustered, longitudinal or multiple‐membership settings. The proper analysis needs to reflect the design of a study. Typically random effects are used to account for dependencies in the data. We examine the h‐likelihood estimation and inference framework for hurdle models with random effects for complex designs. We extend the h‐likelihood procedures to fit hurdle models, thereby extending h‐likelihood to truncated distributions. Two applications of the methodology are presented. Copyright © 2010 John Wiley & Sons, Ltd.
Genetic analysis of age‐at‐onset traits based on case–control family data
Authors: Yip Benjamin H. , Moger Tron Anders , Pawitan Yudi
Published: December 2010

Family studies are a useful alternative to twin studies for disentangling genetic and environmental effects on human diseases. However, although age‐at‐onset traits are often of interest, family‐based quantitative genetic analysis of such data is still not commonly used. One reason is that we need multiple random components to capture the genetic and environmental contributions, so it becomes hard to use the existing frailty models for correlated survival data. In this paper we consider the alternative accelerated failure‐time models with random effects. The method allows both left truncation and right censoring, and it can deal with an arbitrary family structure and multiple random components. For estimation we use the h‐likelihood procedure, which avoids the integration of the random effects in the marginal likelihood approach. To deal with large cohort data, we propose a case–control scheme, where we ascertain all families with at least two events and a subsample of control families. A pseudo‐h‐likelihood approach is used to analyse the ascertained data. We study the performance of the method using simulated data, and provide an illustration with analysis of melanoma in the Swedish population. Copyright © 2010 John Wiley & Sons, Ltd.
Modelling competing risks data with missing cause of failure
Authors: Bakoyannis Giorgos , Siannis Fotios , Touloumi Giota
Published: December 2010

When competing risks data arise, information on the actual cause of failure for some subjects might be missing. Therefore, a cause‐specific proportional hazards model together with multiple imputation (MI) methods have been used to analyze such data. Modelling the cumulative incidence function is also of interest, and thus we investigate the proportional subdistribution hazards model (Fine and Gray model) together with MI methods as a modelling approach for competing risks data with missing cause of failure. Possible strategies for analyzing such data include the complete case analysis as well as an analysis where the missing causes are classified as an additional failure type. These approaches, however, may produce misleading results in clinical settings. In the present work we investigate the bias of the parameter estimates when fitting the Fine and Gray model in the above modelling approaches. We also apply the MI method and evaluate its comparative performance under various missing data scenarios. Results from simulation experiments showed that there is substantial bias in the estimates when fitting the Fine and Gray model with naive techniques for missing data, under missing at random cause of failure. Compared to those techniques the MI‐based method gave estimates with much smaller biases and coverage probabilities of 95 per cent confidence intervals closer to the nominal level. All three methods were also applied on real data modelling time to AIDS or non‐AIDS cause of death in HIV‐1 infected individuals. Copyright 2010 John Wiley & Sons, Ltd.
Improvement of quality of reporting in randomised controlled trials to prevent hypotension after spinal anaesthesia for caesarean section
Authors: Herdan A. , Roth R. , Grass D. , Klimek M. , Will S. , Schauf B. , Rossaint R. , Heesen M.
Published: December 2010

Hypotension is a frequent complication of spinal anaesthesia for caesarean section and can threaten the well-being of the unborn child. Numerous randomised controlled trials (RCTs) dealt with measures to prevent hypotension. The aim of this study was to determine the reporting quality of RCTs using the Consolidated Standards of Reporting Trials (CONSORT) statement since low quality can lend false credibility to a study and overestimate the effect of an intervention. We performed a systematic literature search in PubMed to identify relevant RCTs in a pre-CONSORT period (1990–1994) and a post-CONSORT period (2004–2008). A comparative evaluation was done between the two periods, and the trials were assessed for compliance with each of the 22 CONSORT items. A total of 37 RCTs was identified. The CONSORT score increased significantly (p < 0.05) from 66.7% (±12.5%) in the pre-CONSORT period to 87.4% (±6.9%) in the post-CONSORT period. A statistically significant improvement was found for eight items, including randomization, blinding and intention-to-treat analysis. The CONSORT score in the post-CONSORT era was fairly good, also in comparison to other medical fields. In the post-CONSORT era, reporting of important items improved, in particular in the domains that are crucial to avoid bias and to improve internal validity. Use of CONSORT should be encouraged in order to keep or even improve the reporting quality.
Negative school perceptions and involvement in school bullying: A universal relationship across 40 countries
Authors: Harel‐Fisch Yossi , Walsh Sophie D. , Fogel‐Grinvald Haya , Amitai Gabriel , Pickett William , Molcho Michal , Due Pernille , de Matos Margarida Gaspar , Craig Wendy ,   Members of the HBSC Violence and Injury Prevention Focus Group
Published: December 2010

Cross‐national analyses explore the consistency of the relationship between negative school experiences and involvement in bullying across 40 European and North American countries, using the 2006 (40 countriesn= 197,502) and 2002 (12 countries,n= 57,007) WHO–HBSC surveys. Measures include two Cumulative Negative School Perception (CNSP) scales, one based on 6 mandatory items (2006) and another including an additional 11 items (2002). Outcome measures included bullying perpetration, victimization and involvement as both bully and victim. Logistic regression analyses suggested that children with only 2–3 negative school perceptions, experience twice the relative odds of being involved in bullying as compared with children with no negative school perceptions. Odds Ratios (p< 0.001) increase in a graded fashion according to the CNSP, from about 2.2 to over 8.0. Similar consistent effects are found across gender and almost all countries. Further research should focus on the mechanisms and social context of these relationships.
The Effect of Store Image and Service Quality on Brand Image and Purchase Intention for Private Label Brands
Authors: Wu Paul C.S. , Yeh Gary Yeong-Yuh , Hsiao Chieh-Ru
Published: December 2010

This study aims to investigate the direct effects of store image and service quality on brand image and purchase intention for a private label brand (PLB). This study also investigates the indirect effects mediated by perceived risk and price consciousness on these relationships.

The sample in this study consisted of three hundred and sixty (360) customers of the Watsons and Cosmed chain of drugstores. The pre-test results identified “Watsons” and “My Beauty Diary” as the research brands of the PLB for the two stores, respectively. This study uses LISREL to examine the hypothesized relationships.

This study reveals that (1) store image has a direct and positive effect on the purchase intention of the PLB; (2) service quality has a direct and positive effect on the PLB image; (3) the perceived risk of PLB products has a mediating effect on the relationship between the brand image and the consumers purchase intention of the PLB.
Sailing Injury and Illness: Results of an Online Survey
Authors: Nathanson Andrew T. , Baird Janette , Mello Michael
Published: December 2010

Objective

The purpose of this study was to describe the relative frequency, patterns, and mechanisms of sailing-related injuries in dinghies and keelboats. Data were also collected on risky and risk-averse behaviors of sailors, as well as on sailing-related illnesses.

Methods

A web-based, logic-driven, multiple-choice survey was developed and links were posted on sailing-related websites. Data were collected from March through November 2006 on any injuries or illnesses sailors sustained over the prior 12 months.

Results

From 1188 respondents, a total of 1715 injuries and 559 illnesses was reported. The top 3 injuries for keel boats were leg contusions (11%), hand lacerations (8%), and arm contusions (6%), and in dinghies they were leg contusions (13%), knee contusions (6%), and leg lacerations (6%). The most common mechanisms of injury were “trip/fall,” “hit by object,” and “caught in lines.” Tacking, heavy weather, and jibing were the most common factors contributing to injury. The rates of injury and severe injury in this internet-based survey were 4.6 and 0.57 per 1000 days of sailing, respectively. Of the 70 severe injuries, 25% were fractures, 16% were torn tendons or cartilage, 14% were concussions, and 8% were dislocations. The median rate of lifejacket use was 30%, and median rate of sunscreen use was 80%. Sixteen percent of sailors reported sunburn over the prior 12 months. Seven percent of sailors reported use of alcohol within the 2 hours preceding injury.

Conclusions

The most common injuries in both keel boats and dinghies are soft-tissue injuries to the extremities. Severe injuries and illnesses in sailing are uncommon in this study population.
Envenomation by the Scorpion Tityus breweri in the Guayana Shield, Venezuela: Report of a Case, Efficacy and Reactivity of Antivenom, and Proposal for a Toxinological Partitioning of the Venezuelan Scorpion Fauna
Authors: Borges Adolfo , Rojas-Runjaic Fernando J.M. , Diez Nardy , Faks José G. , Op den Camp Huub J.M. , De Sousa Leonardo
Published: December 2010

Objectives

Scorpion envenomation is a common public health problem in Venezuela. We report an envenoming case by Tityus breweri, endemic to the Guayana Shield, southeast Venezuela, and the outcome of its treatment with antivenom anti– Tityus discrepans. Toxin composition and antigenic reactivity of T breweri venom were also explored. T breweri distribution range was re-evaluated.

Methods

Clinical signs and symptoms in an adult male were recorded after envenoming and treatment with antivenom. Toxin composition and antigenicity of T breweri venom were investigated by polyacrylamide gel electrophoresis, immunoblotting, and mass spectrometry. T breweri distribution range was reassessed by mapping new records of the species.

Results

The moderately severe case (a 21-year-old man) presented autonomic manifestations, including cardiopulmonary and gastrointestinal effects. Full recovery was achieved after anti– T discrepans antivenom administration. T breweri venom contains toxins in the 6–8 kd range that affect voltage-sensitive sodium channels. Based on new records, T breweri distribution area reaches 12 155 km. 2 Inclusion of southeast Venezuela as an endemic area of scorpionism prompted the examination of clinical, immunological, and phylogenetic evidence for suggesting a partitioning of the Venezuelan Tityus fauna into toxinological provinces.

Conclusions

The severity of the case reinforces categorization of the Guayana Shield region as a macroendemic area of scorpionism in Venezuela and allows classification of T breweri as a species of medical importance, with toxins immunologically related to central-eastern Venezuelan Tityus. Partitioning of the territory incorporating multiple criteria may help health authorities establish and implement preventive and therapeutic measures for scorpion envenoming in this region.
Injury and Illness in College Outdoor Education
Authors: Gaudio Flavio G. , Greenwald Peter W. , Holton Mark
Published: December 2010

Objective

Many colleges offer outdoor education courses such as rock climbing, kayaking, and mountain biking. Since these sports may be perceived as dangerous, we describe the prevalence of injuries and illnesses in a large, university-based outdoor education program. We also compare composite incident rates from this outdoor program to those of traditional college sports.

Methods

Cohort of college students participating in either Cornell Outdoor Education (COE) or National Collegiate Athletic Association (NCAA) sports and comparison of incident rates. COE data were prospectively collected in the field; and NCAA data were prospectively collected through the Association's Injury Surveillance System. By definition, a COE injury or illness required follow-up care, prescription medication, or limited course participation. Similarly, a NCAA injury limited further practice or play. Incident rates were calculated as injuries and illnesses per 1000 participant-days (COE) or injuries per 1000 athlete-exposures (NCAA).

Results

Included COE courses during 2002–2007 totaled 74 005 participant-days. There were 111 injuries and illnesses, rate = 1.50/1000 participant-days (95% CI 1.24–1.81). The NCAA reported 32 646 899 athlete-exposures during 1988-2004 and 181 476 injuries, rate = 5.56/1000 athlete-exposures (95% CI 5.53–5.58). Compared to COE, the relative risk of injury in NCAA sports was 3.7 (95% CI 3.1–4.5) overall and 3.3 (95% CI 2.8–4.0) after excluding the high-contact sports of football, ice hockey, and wrestling. For COE, mountain biking had the highest incident rate (7.5/1000), which was significantly lower than game injury rates in NCAA football and soccer. The most common injuries for both NCAA and COE were soft-tissue injuries such as sprains and strains.

Conclusion

Outdoor education at this university-sponsored program was at least as safe as traditional college sports. Overall, college students were less likely to be injured while participating in COE courses than while participating in NCAA sports, even after excluding high-contact sports from the comparison.
Oxidative Stress Status in Rats After Intermittent Exposure to Hypobaric Hypoxia
Authors: Esteva Santiago , Pedret Rafel , Fort Nuria , Torrella Joan Ramon , Pagès Teresa , Viscor Ginés
Published: December 2010

Objective

Programs of intermittent hypobaric hypoxia (IHH) exposure are used to raise hemoglobin concentration and erythrocyte mass. Although acclimation response increases blood oxygen transport capacity leading to a VO2max increase, the effects of reactive oxygen species (ROS) might determine the behavior of erythrocytes and plasma, thus causing a worse peripheral blood flow. The goals of the study were to establish the hematological changes and to discern whether an IHH protocol modifies the antioxidant/pro-oxidant balance in laboratory rats.

Methods

Male rats were subjected to an IHH program consisting of a daily 4-hour session for 5 days/week until completing 22 days of hypoxia exposure in a hypobaric chamber at a simulated altitude of 5000 m. Blood samples were taken at the end of the exposure period (H) and at 20 (P20) and 40 (P40) days after the end of the program, and compared to control (C), maintained at sea-level pressure. Hematological parameters were measured together with several oxidative stress indicators: plasma thiobarbituric acid reactive substances (TBARS) and erythrocyte catalase (CAT) and superoxide dismutasc (SOD).

Results

Red blood cell (RBC) count, hemoglobin concentration and hematocrit were higher in H group as compared to all the other groups ( p < 0.001). However, there were no significant differences between the 4 groups in any of the oxidative stress-related parameters.

Conclusions

The absence of significant differences between groups indicates that our IHH program has little impact on the general redox status, even in the laboratory rat, which is more sensitive to hypoxia than humans. We conclude that IHH does not increase oxidative stress.
Cosmogenic nuclide exposure ages for moraines in the Lago San Martin Valley, Argentina
Authors: Glasser Neil F. , Jansson Krister N. , Goodfellow Bradley W. , de Angelis Hernan , Rodnight Helena , Rood Dylan H.
Published: December 2010

At several times during the Quaternary, a major eastward-flowing outlet glacier of the former Patagonian Ice Sheet occupied the Lago San Martin Valley in Argentina (49°S, 72°W). We present a glacial chronology for the valley based on geomorphological mapping and cosmogenic nuclide (10Be) exposure ages (n= 10) of boulders on moraines and lake shorelines. There are five prominent moraine belts in the Lago San Martin Valley, associated with extensive sandar (glaciofluvial outwash plains) and former lake shorelines. Cosmogenic nuclide exposure ages for boulders on these moraines indicate that they formed at 14.3 ± 1.7 ka, 22.4 ± 2.3 ka, 34.4 ± 3.4 ka to 37.6 ± 3.4 ka (and possibly 60 ± 3.5 ka), and 99 ± 11 ka (1σ). These dated glacier advances differ from published chronologies from the Lago San Martin Valley based on14C age determinations from organic sediments and molluscs in meltwater channels directly in front of moraines or in kettleholes within end moraine ridges. The moraine boulder ages also point to possible pre-LGM glacial advances during the last glacial cycle and a key observation from our data is that the LGM glaciers were probably less extensive in the Lago San Martin Valley than previously thought.
Evidence of Different Developmental Trajectories for Length Estimation According to Egocentric and Allocentric Viewpoints in Children and Adults
Authors: Poirel Nicolas , Vidal Manuel , Pineau Arlette , Lanoë Céline , Leroux Gaëlle , Lubin Amélie , Turbelin Marie-Renée , Berthoz Alain , Houdé Olivier
Published: December 2010

This study investigated the influence of egocentric and allocentric viewpoints on a comparison task of length estimation in children and adults. A total of 100 participants ranging in age from 5 years to adulthood were presented with virtual scenes representing a park landscape with two paths, one straight and one serpentine. Scenes were presented either from an egocentric or allocentric viewpoint. Results showed that when the two paths had the same length, participants always overestimated the length of the straight line for allocentric trials, whereas a development from a systematic overestimation in children to an underestimation of the straight line length in adults was found for egocentric trials. We discuss these findings in terms of the influences of both bias-inhibition processes and school acquisitions.
Multiple-Object Tracking
Authors: Botterill K. , Allen R. , McGeorge P.
Published: December 2010

The Multiple-Object Tracking paradigm has most commonly been utilized to investigate how subsets of targets can be tracked from among a set of identical objects. Recently, this research has been extended to examine the function of featural information when tracking is of objects that can be individuated. We report on a study whose findings suggest that, while participants can only hold featural information for roughly two targets this task does not affect tracking performance detrimentally and points to a discontinuity between the cognitive processes that subserve spatial location and featural information.
The Effect of Negative Emotion on Deductive Reasoning
Authors: Blanchette Isabelle , Leese Joanna
Published: December 2010

In three experiments, we explore the link between peripheral physiological arousal and logicality in a deductive reasoning task. Previous research has shown that participants are less likely to provide normatively correct responses when reasoning about emotional compared to neutral contents. Which component of emotion is primarily involved in this effect has not yet been explored. We manipulated the emotional value of the reasoning stimuli through classical conditioning (Experiment 1), with simultaneous presentation of negative/neutral pictures (Experiment 2), or by using intrinsically negative/neutral words (Experiment 3). We measured skin conductance (SC) and subjective affective ratings of the stimuli. In all experiments, we observed a negative relationship between SC and logicality. Participants who showed greater SC reactivity to negative stimuli compared to neutral stimuli were more likely to make logical errors on negative, compared to neutral reasoning contents. There was no such link between affective ratings of the stimuli and the effect of emotion on reasoning.
Mapping seismic anisotropy using harmonic decomposition of receiver functions: An application to Northern Apennines, Italy
Authors: Bianchi I. , Park J. , Piana Agostinetti N. , Levin V.
Published: December 2010

Isotropic and anisotropic seismic structures across the Northern Apennines (Italy) subduction zone are imaged using a new method for the analysis of teleseismic receiver functions (RFs). More than 13,000 P‐wave coda of teleseismic records from the 2003–2007 Retreating‐Trench, Extension, and Accretion Tectonics (RETREAT) experiment are used to provide new insights into a peculiar subduction zone between two continental plates that is considered a focal point of Mediterranean evolution. A new methodology for the analysis of receiver functions is developed, which combines both migration and harmonic decomposition of the receiver function data set. The migration technique follows a classical “Common Conversion Point” scheme and helps to focus on a crucial depth range (20–70 km) where the mantle wedge develops. Harmonic decomposition of a receiver function data set is a novel and less explored approach to the analysis of P‐to‐S converted phases. The separation of the back‐azimuth harmonics is achieved through a numerical regression of the stacked radial and transverse receiver functions from which we obtain independent constraints on both isotropic and anisotropic seismic structures. The application of our method to the RETREAT data set succeeds both in confirming previous knowledge about seismic structure in the area and in highlighting new structures beneath the Northern Apennines chain, where previous studies failed to clearly retrieve the geometry of the subducted interfaces. We present our results in closely spaced profiles across and along the Northern Apennines chain to highlight the convergence of the Tyrrhenian and the Adriatic microplates which differ in their crustal structure where the Adriatic microplate subducts beneath Tuscany and the Tyrrhenian sea. A signature of the dipping Adriatic Moho is clearly observed beneath the Tyrrhenian Moho in a large portion of the forearc region. In the area where the two Mohos overlap, our new analysis reveals the presence of an anisotropic body above the subducted Moho. There is a strong Ps converted phase with anisotropic characteristics from the top of the Adriatic plate to a depth of at least 80 km. Because the Ps conversion occurs much deeper than similar Ps phases in Cascadia and Japan, dehydration of oceanic crust seems unlikely as a causative factor. Rather, the existence of this body trapped between the two interfaces supports the hypothesis of lower crustal delamination in a postsubduction tectonic setting.
Introduction to special section on Phenomenology, Underlying Processes, and Hazard Implications of Aseismic Slip and Nonvolcanic tremor
Authors: Gomberg Joan
Published: December 2010

This paper introduces the special section on the “phenomenology, underlying processes, and hazard implications of aseismic slip and nonvolcanic tremor” by highlighting key results of the studies published in it. Many of the results indicate that seismic and aseismic manifestations of slow slip reflect transient shear displacements on the plate interface, with the outstanding exception of northern Cascadia where tremor sources have been located on and above the plate interface (differing models of the plate interface there also need to be reconciled). Slow slip phenomena appear to result from propagating deformation that may develop with persistent gaps and segment boundaries. Results add to evidence that when tectonic deformation is relaxed via slow slip, most relaxation occurs aseismically but with seismic signals providing higher‐resolution proxies for the aseismic slip. Instead of two distinct slip modes as suggested previously, lines between “fast” and “slow” slip more appropriately may be described as blurry zones. Results reported also show that slow slip sources do not coincide with a specific temperature or metamorphic reaction. Their associations with zones of high conductivity and low shear to compressional wave velocity ratios corroborate source models involving pore fluid pressure buildup and release. These models and spatial anticorrelations between earthquake and tremor activity also corroborate a linkage between slow slip and frictional properties transitional between steady state and stick‐slip. Finally, this special section highlights the benefits of global and multidisciplinary studies, which demonstrate that slow phenomena are not confined to beneath the locked zone but exist in many settings.
The implementation and perception of an OSCE
Authors: Jeppe‐Jensen D. , Larsen T.
Published: December 2010

The purpose of the present study was to introduce an objective structured clinical examination (OSCE) for educational purposes at a dental school with a rather traditional curriculum in order to encourage reflective thinking in the students. Sixty‐eight third year students in pairs participated in an interdisciplinary OSCE in cariology and microbiology. All stations were based upon one patient testing knowledge, clinical reasoning, verbal communication and practical procedures. At each station, immediate verbal feedback was given to the students by a teacher on the basis of pre‐defined criteria. Further written marks (individual and group averages) were given to the students the following week. After the OSCE, the students and the teachers answered a questionnaire about the OSCE. For practical reasons, the OSCE had to be performed over 3 days and most of the stations to be run by several teachers. The average results obtained by each group did not seem to improve during the week. About half of the students stated not to have discussed the questions with others. There was no apparent systematic variation in the marking of the individual teachers over time. Neither were there major differences between different teachers at the same station, though one teacher marked somewhat lower. Both students and teachers found the OSCE well organised and the questions highly relevant providing an educational benefit. Students as well as teachers perceived the OSCE as a very useful method of clinical assessment, and the vast majority found that OSCEs could also replace parts of the traditional written exams.

In conclusion, the OSCE was positively received by students as well as teachers and is recommended for implementation in the curriculum for educational purposes as well as assessment.
Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. I. The formation of the ppσ-network
Authors: Zhugayevych Andriy , Lubchenko Vassiliy
Published: December 2010

Semiconductor glasses exhibit many unique optical and electronic anomalies. We have put forth a semiphenomenological scenario [A. Zhugayevych and V. Lubchenko, J. Chem. Phys. 133, 234504 (2010)] in which several of these anomalies arise from deep midgap electronic states residing on high-strain regions intrinsic to the activated transport above the glass transition. Here we demonstrate at the molecular level how this scenario is realized in an important class of semiconductor glasses, namely chalcogen and pnictogen containing alloys. Both the glass itself and the intrinsic electronic midgap states emerge as a result of the formation of a network composed of σ-bonded atomic p-orbitals that are only weakly hybridized. Despite a large number of weak bonds, these ppσ-networks are stable with respect to competing types of bonding, while exhibiting a high degree of structural degeneracy. The stability is rationalized with the help of a hereby proposed structural model, by which ppσ-networks are symmetry-broken and distorted versions of a high symmetry structure. The latter structure exhibits exact octahedral coordination and is fully covalently bonded. The present approach provides a microscopic route to a fully consistent description of the electronic and structural excitations in vitreous semiconductors.
Rotational dependence of the proton-transfer reaction HBr+ + CO2 → HOCO+ + Br. II. Comparison of HBr+ (2Π3/2) and HBr+ (2Π1/2)
Authors: Paetow Lisa , Unger Franziska , Beutel Bernd , Weitzel Karl-Michael
Published: December 2010

The effects of reactant ion rotational excitation on the exothermic proton-transfer reactions of HBr+(2Π1/2) and DBr+(2Π1/2), respectively, with CO2 were studied in a guided ion beam apparatus. Cross sections are presented for collision energies in the center of mass system Ec.m. in the range of 0.23 to 1.90 eV. The HBr+/DBr+ ions were prepared in a state-selective manner by resonance enhanced multiphoton ionization. The mean rotational energy was varied from 3.4 to 46.8 meV for HBr+(2Π1/2) and from 1.8 to 40.9 meV for DBr+(2Π1/2). Both reactions studied are inhibited by collision energy, as expected for exothermic reactions. For all collision energies considered, the cross section decreases with increasing rotational energy of the ion, but the degree of the rotational dependence differs depending on the collision energy. For Ec.m. = 0.31 eV, the cross sections of the deuteron transfer are significantly larger than those of the proton transfer. For higher Ec.m. they differ very little. The current results for the exothermic proton transfer are systematically compared to previously published data for the endothermic proton transfer starting from HBr+(2Π3/2) [L. Paetow et al., J. Chem. Phys. 132, 174305 (2010)]. Additional new data regarding the latter reaction are presented to further confirm the conclusions. The dependences on rotational excitation found cannot be explained by the corresponding change in the total energy of the system. For both the endothermic and the exothermic reaction, the cross section is maximized for the smallest rotational energy, at least well above the threshold.
Electron delocalization of tensily strained GaAs quantum dots in GaSb matrix
Authors: Lin T. C. , Wu Y. H. , Li L. C. , Sung Y. T. , Lin S. D. , Chang L. , Suen Y. W. , Lee C. P.
Published: December 2010

The magneto-optical response of type-II tensily strained GaAs self-assembled quantum dots in GaSb was investigated in magnetic fields up to 14 T. By depositing different GaAs amount, the dot sizes and the corresponding emission energies were varied. We analyzed the carrier wave function extent of different dots using the diamagnetic shift results. It was found that, with the increase in the energy (the reduction in the dot size), the diamagnetic coefficient first rises quickly and then saturates at around 21 μeV/T2. Based on a simple calculation model, this unusual tendency is attributed to the electrons gradually spilling out of the quantum dot to the wetting layer as the dots get smaller. This delocalization effect is enhanced in this material system due to the tensile strain relaxation within the dots, which raises the conduction band edge over that in the wetting layer.
Highly efficient yellow photoluminescence from {11–22} InGaN multiquantum-well grown on nanoscale pyramid structure
Authors: Kim Taek , Kim Joosung , Yang Moon-Seung , Lee Sangmoon , Park Youngsoo , Chung U-In , Cho Yonghoon
Published: December 2010

InGaN/GaN multiquantum wells (MQWs) with a peak wavelength of 570 nm are grown on nanosize GaN hexagonal pyramid structures. Temperature dependent photoluminescence (PL) measurements from 10 to 300 K show a high integrated intensity ratio of 0.45. The emission energy of the MQW monotonically decreases with temperature increase, showing the absence of localized potential. Power dependent PL shows no noticeable blueshift caused by piezoelectric field screening effect. Comparative study of the PL results with those of the InGaN MQW on microsize pyramid show that nanosize pyramids play an important role in suppressing piezoelectric field in addition to the semipolar growth direction. We attribute the high luminescence efficiency of the MQW on nanosize pyramid structures to effectively suppressed piezoelectric field and potential localization.
Communication: Emergence of localized magnetic moment at adsorbed beryllium dimer on graphene
Authors: He Xiang , Chen Zhao-Xu , Li Zhaosheng , Zou Zhigang
Published: December 2010

Graphene with significant and stable magnetic moment is expected to have various promising applications in electronics. The conventional way to magnetize graphene is to dope paramagnetic adsorbates onto it. However, this method usually induces fractional charge transfer, which decreases the total magnetic moment. Contrary to the conventional way and widely held point of view that diamagnetic adsorbates are weak dopants, for the first time we report our theoretical findings that doping the diamagnetic beryllium dimer on perfect diamagnetic graphene produces a stable system with a local magnetic moment as large as 1 \documentclass[12pt]{minimal}\begin{document}$\mu _B$\end{document}μB. It is revealed that this process is realized through the spin-polarized electron transfer.
Photon spin-to-orbital angular momentum conversion via an electrically tunable q-plate
Authors: Piccirillo Bruno , D’Ambrosio Vincenzo , Slussarenko Sergei , Marrucci Lorenzo , Santamato Enrico
Published: December 2010

Exploiting electro-optic effects in liquid crystals, we achieved real-time control of the retardation of liquid-crystal-based q-plates through an externally applied voltage. Electro-optic q-plates can be operated as electrically driven converters of photon spin into orbital angular momentum, enabling a variation of the orbital angular momentum probabilities of the output photons over a time scale of milliseconds.
Human-provoked amphibian decline in central Italy and the efficacy of protected areas
Authors: D'Amen Manuela , Pietrangeli Biancamaria , Bologna Marco A.
Published: December 2010

Context Today, more than 32% of amphibian species are threatened and more than 43% face a steep decline in numbers. Most species are being affected simultaneously by multiple stressors and habitat protection is often inadequate to prevent declines. Aims The main goal of the present research was to understand the consequences of alternative human land use in producing landscape disturbance for amphibians. At the same time, we also evaluated the effect of changing climatic conditions as additional potential drivers of population decline. Another goal was to determine whether and to what extent the existing nature reserves have been effective in protecting species in recent decades. Methods We used generalised additive models (GAMs) to investigate the association between the state (stable/decline) of amphibian populations in 5 × 5 km cells in central Italy and proxies of different typology of anthropogenic stressors, climatic variables and protection measures. Key results We found a significant association between anthropogenic landscape modifications and species decline. This negative relationship was revealed with agricultural predictors for the majority of the species, whereas urban fabrics had a slightly smaller impact. We found significant associations between amphibian declines and climatic variation, particularly the increasing number of dry days. Protected areas protected declines of two species only. Conclusions Our results showed that the status of amphibians in this region warrants greater attention than has been given previously. The detrimental effect of agricultural practices, combined with increasing aridity, makes amphibian populations particularly susceptible to extinction, and the conservation measures applied till now are inadequate for species protection in this region. Implications Our results should stimulate the implementation of environmental policies that focus not only on the protection of single habitats, but also on ensuring the environmental quality of the surrounding landscapes. Moreover, an adaptive management approach should be applied to take into account future modification of hydrology and climate.
Structural shifts of aldehyde dehydrogenase enzymes were instrumental for the early evolution of retinoid-dependent axial patterning in metazoans
Authors: Sobreira Tiago J. P. , Marlétaz Ferdinand , Simões-Costa Marcos , Schechtman Deborah , Pereira Alexandre C. , Brunet Frédéric , Sweeney Sarah , Pani Ariel , Aronowicz Jochanan , Lowe Christopher J. , Davidson Bradley , Laudet Vincent , Bronner Marianne , de Oliveira Paulo S. L. , Schubert Michael , Xavier-Neto José
Published: December 2010

Aldehyde dehydrogenases (ALDHs) catabolize toxic aldehydes and process the vitamin A-derived retinaldehyde into retinoic acid (RA), a small diffusible molecule and a pivotal chordate morphogen. In this study, we combine phylogenetic, structural, genomic, and developmental gene expression analyses to examine the evolutionary origins of ALDH substrate preference. Structural modeling reveals that processing of small aldehydes, such as acetaldehyde, by ALDH2, versus large aldehydes, including retinaldehyde, by ALDH1A is associated with small versus large substrate entry channels (SECs), respectively. Moreover, we show that metazoan ALDH1s and ALDH2s are members of a single ALDH1/2 clade and that during evolution, eukaryote ALDH1/2s often switched between large and small SECs after gene duplication, transforming constricted channels into wide opened ones and vice versa. Ancestral sequence reconstructions suggest that during the evolutionary emergence of RA signaling, the ancestral, narrow-channeled metazoan ALDH1/2 gave rise to large ALDH1 channels capable of accommodating bulky aldehydes, such as retinaldehyde, supporting the view that retinoid-dependent signaling arose from ancestral cellular detoxification mechanisms. Our analyses also indicate that, on a more restricted evolutionary scale, ALDH1 duplicates from invertebrate chordates (amphioxus and ascidian tunicates) underwent switches to smaller and narrower SECs. When combined with alterations in gene expression, these switches led to neofunctionalization from ALDH1-like roles in embryonic patterning to systemic, ALDH2-like roles, suggesting functional shifts from signaling to detoxification.
pH-sensitivity of the ribosomal peptidyl transfer reaction dependent on the identity of the A-site aminoacyl-tRNA
Authors: Johansson Magnus , Ieong Ka-Weng , Trobro Stefan , Strazewski Peter , Åqvist Johan , Pavlov Michael Y. , Ehrenberg Måns
Published: December 2010

We studied the pH-dependence of ribosome catalyzed peptidyl transfer from fMet-tRNA
fMet
to the aa-tRNAs Phe-tRNA
Phe
, Ala-tRNA
Ala
, Gly-tRNA
Gly
, Pro-tRNA
Pro
, Asn-tRNA
Asn
, and Ile-tRNA
Ile
, selected to cover a large range of intrinsic
pK

a

-values for the α-amino group of their amino acids. The peptidyl transfer rates were different at pH 7.5 and displayed different pH-dependence, quantified as the pH-value,

, at which the rate was half maximal. The

-values were downshifted relative to the intrinsic
pK

a

-value of aa-tRNAs in bulk solution. Gly-tRNA
Gly
had the smallest downshift, while Ile-tRNA
Ile
and Ala-tRNA
Ala
had the largest downshifts. These downshifts correlate strongly with molecular dynamics (MD) estimates of the downshifts in
pK

a

-values of these aa-tRNAs upon A-site binding. Our data show the chemistry of peptide bond formation to be rate limiting for peptidyl transfer at pH 7.5 in the Gly and Pro cases and indicate rate limiting chemistry for all six aa-tRNAs.