bluuebunny/crossref_metadata_2025 huggingface dataset:
Volcanic glass under fire – a comparison of three complementary analytical methods
Authors: Eder Fabienne M. , Neelmeijer Christian , Pearce Nicholas J.G. , Bichler Max , Sterba Johannes H. , Ntaflos Theodoros , Merchel Silke
Published: July 2013

The two obsidian sources from the island of Melos (Greece), Agia Nychia and Demenegakion, are chemically characterized by three complementary analytical techniques. Ion beam analysis (IBA) comprising particle induced X‐ray emission and particle induced gamma‐ray emission, neutron activation analysis (NAA) and laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) is applied to the same set of geological obsidian samples.

The combination of methods allows a more complete characterization of obsidian sources and reveals a highly specific chemical composition, the so‐called chemical fingerprint. This multi‐methodical approach checks also the self‐consistency of the analytical results and shows not only the most reliable and characteristic key elements Co and Sc but also Fe, Ca and Ti of Melos obsidian deposits. NAA contributes the largest number of reliable elements to the most unambiguous chemical fingerprint comprising in total of 41 elements. Therefore, NAA is the most suitable analytical method for a clear identification of Melos obsidian deposits.

Moreover, the accuracy of methods is demonstrated by the excellent correspondences (calculated correlation coefficient R2 = 1.00 for IBA and NAA, R2 = 0.99 for LA‐ICP‐MS) between determined analytical results obained by IBA, NAA and LA‐ICP‐MS and certified values of the reference glass BAM‐S005B. Copyright © 2013 John Wiley & Sons, Ltd.
TXRF quantification of interfering heavy metals using deconvolution, cross‐correlation, and external standard calibration
Authors: Santibáñez M. , Bennun L. , Marcó‐Parra L. M.
Published: July 2013

We developed a general procedure that includes external standard calibration and a deconvolution of spectral signals, which determined with high accuracy the relative proportion and absolute quantification of elements that habitually overlap in total reflection X‐ray fluorescence spectroscopy. The deconvolution proposed takes advantage of the well‐known method of a cross‐correlation technique, offering improvements in identification of simultaneous signals and in the determination of the relative elemental proportions. The external standard calibration was studied determining its range of application for the elements of interest and implemented in certified standard samples producing excellent results for the quantification of the mentioned elements. In this paper, we show the quality of the results obtained for specific heavy metals of currently health and industrial interest in the range of linear response of 0.2–200 ng. Copyright © 2013 John Wiley & Sons, Ltd.
Usefulness of Drain Amylase, Serum C‐Reactive Protein Levels and Body Temperature to Predict Postoperative Pancreatic Fistula After Pancreaticoduodenectomy
Authors: Hiyoshi Masahide , Chijiiwa Kazuo , Fujii Yoshiro , Imamura Naoya , Nagano Motoaki , Ohuchida Jiro
Published: July 2013

Background

Postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD) is a worrisome and life‐threatening complication. Recently, early drain removal has been recommended as a means of preventing POPF. The present study sought to determine how to distinguish clinical POPF from non‐clinical POPF in the early postoperative period after PD to aid in early drain removal.

Methods

From March 2002 through December 2010, 176 patients underwent PD and were enrolled in this study to examine factors predictive of clinical POPF after PD. POPF was defined and classified according to the International Study Group of Pancreatic Surgery guideline, and grade B/C POPF was defined as clinical POPF.

Results

Grade A POPF occurred in 39 (22.2 %) patients, grade B in 19 (10.8 %) patients, and grade C in 11 (6.3 %) patients. Clinical POPF (grade B/C) occurred in 17.1 % of patients. Multivariate analysis revealed male gender and body mass index (BMI) ≥22.5 kg/m2 to be the independent preoperative risk factors predictive of POPF. Receiver operating characteristic curves showed that the combination of drain amylase ≥750 IU/L, C‐reactive protein (CRP) ≥20 mg/dL, and body temperature ≥37.5 °C on postoperative day 3 could effectively distinguish clinical POPF from non‐clinical POPF. Sensitivity, specificity, and accuracy were 84.6, 98.2, and 95.7 %, respectively.

Conclusions

Male gender and BMI ≥22.5 were the independent preoperative predictive risk factors for POPF. We assume that when amylase is <750 IU/L, serum CRP is <20 mg/dL, and body temperature is <37.5 °C the drain can safely be removed, even if POPF is indicated.
Twenty-First-Century Fiction
Authors: Boxall Peter
Published: July 2013

The widespread use of electronic communication at the dawn of the twenty-first century has created a global context for our interactions, transforming the ways we relate to the world and to one another. This critical introduction reads the fiction of the past decade as a response to our contemporary predicament – one that draws on new cultural and technological developments to challenge established notions of democracy, humanity, and national and global sovereignty. Peter Boxall traces formal and thematic similarities in the novels of contemporary writers including Don DeLillo, Margaret Atwood, J. M. Coetzee, Marilynne Robinson, Cormac McCarthy, W. G. Sebald and Philip Roth, as well as David Mitchell, Chimamanda Ngozi Adichie, Dave Eggers, Ali Smith, Amy Waldman and Roberto Bolaño. In doing so, Boxall maps new territory for scholars, students and interested readers of today's literature by exploring how these authors narrate shared cultural life in the new century.
Dressing Constitutionally
Authors: Robson Ruthann
Published: July 2013

This book examines how the intertwining of clothes and the United States Constitution raises fundamental questions of hierarchy, sexuality and democracy. Constitutional considerations both constrain and confirm daily choices. In turn, appearances provide multilayered perspectives on the Constitution and its interpretations. Garments often raise First Amendment issues of expression or religion, but they also prompt questions of equality on the basis of gender, race and sexuality. At work, in court, in schools, in prisons and on the streets, clothes and grooming provoke constitutional controversies. Additionally, the production, trade and consumption of apparel implicates constitutional concerns including colonial sumptuary laws, slavery, wage and hour laws, and current notions of free trade. The regulation of what we wear - or do not - is ubiquitous. From a noted constitutional scholar and commentator, this book examines the rights to expression and equality, as well as the restraints on government power, as they both limit and allow control of our most personal choices of attire and grooming.
Integration of Passive RF Front End Components in SoCs
Authors: Darabi Hooman , Mirzaei Ahmad
Published: July 2013

Examining the most important developments in highly integrated wireless RF front ends, this book describes and evaluates both active and passive solutions for on-chip high-Q filtering, and explores M-phase filters in depth. An accessible step-by-step approach is used to introduce everything an RF designer needs to know about these filters, including their various forms, principles of operation, and their performance against implementation-related imperfections. Real-world examples are described in depth, and detailed mathematical analyses demonstrate the practical quantification of pertinent circuit parameters.
State Responsibility
Authors: Crawford James
Published: July 2013

Annexed to GA Resolution 56/83 of 2001, the International Law Commission's Articles on Responsibility for Internationally Wrongful Acts put the international law of responsibility on a sound footing. As Special Rapporteur for the second reading, James Crawford helped steer it to a successful conclusion. With this book, he provides a detailed analysis of the general law of international responsibility and the place of state responsibility in particular within that framework. It serves as a companion to The International Law Commission's Articles on State Responsibility: Introduction, Text and Commentaries (Cambridge University Press, 2002) and is essential reading for scholars and practitioners concerned with issues of international responsibility, whether they arise in interstate relations, in the context of arbitration or litigation, or in bringing international claims.
Music in Germany since 1968
Authors: Williams Alastair
Published: July 2013

Music in Germany since 1968 modifies the dominant historiography of music in post-war Germany by shifting its axis from the years of reconstruction after 1945 to the era following the events of 1968. Arguing that the social transformations of 1968 led to a new phase of music in Germany, Alastair Williams examines the key topics, including responses to serialism, music and politics, and the re-evaluation of tradition. The book devotes central chapters to Helmut Lachenmann and Wolfgang Rihm, as focal points for areas such as postmodernism, musical semiotics and action-based gestures. Further chapters widen the scope by considering the precursors and contemporaries of Rihm and Lachenmann, especially in relation to the idea of historical inclusion. Williams's study also assesses the development of the Darmstadt summer courses, addresses the significance of German reunification, and considers the role of Germany in a new stage of musical modernism.
Play, Playfulness, Creativity and Innovation
Authors: Bateson Patrick , Martin Paul
Published: July 2013

What role does playful behaviour and playful thought take in animal and human development? How does play relate to creativity and, in turn, to innovation? Unravelling the different meanings of 'play', this book focuses on non-aggressive playful play. The authors emphasise its significance for development and evolution, before examining the importance of playfulness in creativity. This discussion sheds new light on the links between creativity and innovation, distinguishing between the generation of novel behaviour and ideas on the one hand, and the implementation of these novelties on the other. The authors then turn to the role of play in the development of the child and to parallels between play, humour and dreaming, along with the altered states of consciousness generated by some psychoactive drugs. A final chapter looks forward to future research and to what remains to be discovered in this fascinating and important field.
Terahertz Physics
Authors: Lewis R. A.
Published: July 2013

Terahertz physics covers one of the least explored but richest regions of the electromagnetic spectrum. Designed for independent learning, this is the first book to open up this exciting new field to students of science and engineering. Written in a clear and consistent style, the textbook focuses on an understanding of fundamental physical principles at terahertz frequencies and their applications. Part I outlines the foundations of terahertz science, starting with the mathematical representation of oscillations before exploring terahertz-frequency light, terahertz phenomena in matter and the terahertz interactions between light and matter. Part II covers components of terahertz technology, from sources of terahertz frequency radiation, through the manipulation of the radiation, to its detection. Part III deals with applications, including time-domain spectroscopy. Highlighting modern developments and concepts, the book is ideal for self-study. It features precise definitions, clear explanations, instructive illustrations, fully worked examples, numerous exercises and a comprehensive glossary.
Singapore English
Authors: Leimgruber Jakob R. E.
Published: July 2013

In recent years the study of English and its global varieties has grown rapidly as a field of study. The English language in Singapore, famous for its vernacular known as 'Singlish', is of particular interest to linguists because it takes accent, dialect and lexical features from a wide range of languages including Malay, Mandarin, Hokkien and Tamil, as well as being influenced by the Englishes of Britain, Australia and America. This book gives a comprehensive overview of English in Singapore by setting it within a historical context and drawing on recent developments in the field of indexicality, world Englishes and corpus research. Through application of the indexicality framework Jakob Leimgruber offers readers a new way of thinking about and analysing the unique syntactic, semantic and phonological structure of Singapore English. This book is ideal for researchers and advanced students interested in Singapore and its languages.
Statistical Data Analysis for the Physical Sciences
Authors: Bevan Adrian
Published: July 2013

Data analysis lies at the heart of every experimental science. Providing a modern introduction to statistics, this book is ideal for undergraduates in physics. It introduces the necessary tools required to analyse data from experiments across a range of areas, making it a valuable resource for students. In addition to covering the basic topics, the book also takes in advanced and modern subjects, such as neural networks, decision trees, fitting techniques and issues concerning limit or interval setting. Worked examples and case studies illustrate the techniques presented, and end-of-chapter exercises help test the reader's understanding of the material.
Power, Powerlessness and Addiction
Authors: Orford Jim
Published: July 2013

Addiction exercises enormous power over all those who are touched by it. This book argues that power and powerlessness have been neglected in addiction studies and that they are a unifying theme that brings together different areas of research from the field including the disempowering nature of addiction; effects on family, community and the workplace; epidemiological and ethnographic work; studies of the legal and illegal supply; and theories of treatment and change. Examples of alcohol, drug and gambling addiction are used to discuss the evidence that addiction is most disempowering where social resources to resist it are weakest; the ways in which the dominant discourses about addictive behaviour encourage the attributing of responsibility for addiction to individuals and divert attention from the powerful who benefit from addiction; and the ways in which the voices of those whose interests are least well-served by addiction are silenced.
Singularities of the Minimal Model Program
Authors: Kollár János , Kovács Sándor
Published: July 2013

This book gives a comprehensive treatment of the singularities that appear in the minimal model program and in the moduli problem for varieties. The study of these singularities and the development of Mori's program have been deeply intertwined. Early work on minimal models relied on detailed study of terminal and canonical singularities but many later results on log terminal singularities were obtained as consequences of the minimal model program. Recent work on the abundance conjecture and on moduli of varieties of general type relies on subtle properties of log canonical singularities and conversely, the sharpest theorems about these singularities use newly developed special cases of the abundance problem. This book untangles these interwoven threads, presenting a self-contained and complete theory of these singularities, including many previously unpublished results.
Political Performance and Leadership Persona: The UK Labour Party Conference of 2012
Authors: Gaffney John , Lahel Amarjit
Published: July 2013

This article is a contribution to an emerging scholarship on the role of rhetoric, persona and celebrity, and the effects of performance on the political process. We analyse party leader Ed Miliband at the UK Labour Party Conference in Manchester in 2012. Our analysis identifies how, through performance of ‘himself’ and the beginnings of the deployment of an alternative party narrative centred on ‘One Nation’, Ed Miliband began to revise his ‘received persona’. By using a range of rhetorical and other techniques, Miliband began to adapt the Labour narrative to the ‘personalized political’. The article sets out the theoretical framework for the analysis and returns to the implications for the theory of leadership performance in its conclusion.
Cause and effect in studies on unemployment, mental health and suicide: a meta-analytic and conceptual review
Authors: Milner A. , Page A. , LaMontagne A. D.
Published: July 2013

Background

There are ongoing questions about whether unemployment has causal effects on suicide as this relationship may be confounded by past experiences of mental illness. The present review quantified the effects of adjustment for mental health on the relationship between unemployment and suicide. Findings were used to develop and interpret likely causal models of unemployment, mental health and suicide.

Method

A random-effects meta-analysis was conducted on five population-based cohort studies where temporal relationships could be clearly ascertained.

Results

Results of the meta-analysis showed that unemployment was associated with a significantly higher relative risk (RR) of suicide before adjustment for prior mental health [RR 1.58, 95% confidence interval (CI) 1.33–1.83]. After controlling for mental health, the RR of suicide following unemployment was reduced by approximately 37% (RR 1.15, 95% CI 1.00–1.30). Greater exposure to unemployment was associated with higher RR of suicide, and the pooled RR was higher for males than for females.

Conclusions

Plausible interpretations of likely pathways between unemployment and suicide are complex and difficult to validate given the poor delineation of associations over time and analytic rationale for confounder adjustment evident in the revised literature. Future research would be strengthened by explicit articulation of temporal relationships and causal assumptions. This would be complemented by longitudinal study designs suitable to assess potential confounders, mediators and effect modifiers influencing the relationship between unemployment and suicide.
Design and efficient operation of a coaxial RBWO
Authors: Teng Y. , Chen C.H. , Shao H. , Sun J. , Song Z.M. , Xiao R.Z. , Du Z.Y.
Published: July 2013

Coaxial relativistic backward wave oscillator with the rippled inner conductor not only increases the output efficiency but also results in the serious phenomenon of pulse shortening in experiments. Our research indicates that the two main mechanisms leading to the pulse shortening are the electron beam interruption and combining effects of the explosive field electron emission and the secondary electron multipactor on the surface of the slow-wave structure. In order to enhance its power capacity the electrodynamic structure is modified by detailed analysis of the field distribution in the coaxial slow-wave structure. The appropriate resonant reflector and the electron collector are developed for the application of the coaxial relativistic backward wave oscillator. A series of surface treatment is applied to enhance the power capacity of the coaxial RBWO. In the experiment, the microwave pulse duration is increased from less than 10 ns to 20 ns, and the output efficiency is enhanced from less than 20% to 34% employing the electron beam pulse of the full width at half maximum 28 ns. The peak power of 1.01 GW at the frequency of 7.4 GHz is achieved. It is found that the output efficiency of the coaxial RBWO is likely to be advanced if its power capacity can be boosted further.
Simulations of interactions of high-energy proton beam with high dense matter based on two-dimensional quantum hydrodynamic model
Authors: Zhang Ya , Song Yuan-Hong , Wang You-Nian
Published: July 2013

This paper presents numerical simulations to study the heating of a solid target under a proton beam pulse interaction. The target is heated by the proton beam pulse with particle energyEb, intensityNand focal radiusrbof transverse Gaussian distribution, with a fixed pulse time 10 ps. The dynamics of target and beam ions are described by a classical hydrodynamic model and the target electrons are described by the quantum hydrodynamic model. Numerical simulations are carried out by employing the two dimensional flux-corrected transport methods. The target is heated to 0.5−5 eV, therefore, warm dense matter is created in the heated target region on a picosecond time scale.
Collisions at infinity in hyperbolic manifolds
Authors: MCREYNOLDS D. B. , REID ALAN W. , STOVER MATTHEW
Published: July 2013

For a complete, finite volume real hyperbolic n-manifold M, we investigate the map between homology of the cusps of M and the homology of M. Our main result provides a proof of a result required in a recent paper of Frigerio, Lafont and Sisto.
The origins of city: Paseo
Authors: Steane Mary Ann , Monge David Jolly , Aravena Marcelo Araya
Published: July 2013

It was neither with music or an acoustic, but with a sense of origin that we wanted to build the work. A work that seeks, is still in the seeking, in search of establishing a road.
Rapamycin and omega‐1: mTOR‐dependent and ‐independent Th2 skewing by human dendritic cells
Authors: Hussaarts Leonie , Smits Hermelijn H , Schramm Gabriele , van der Ham Alwin J , van der Zon Gerard C , Haas Helmut , Guigas Bruno , Yazdanbakhsh Maria
Published: July 2013

Recent reports have attributed an immunoregulatory role to the mammalian target of rapamycin (mTOR), a key serine/threonine protein kinase integrating input from growth factors and nutrients to promote cell growth and differentiation. In the present study, we investigated the role of the mTOR pathway in Th2 induction by human monocyte‐derived dendritic cells (moDCs). Using a co‐culture system of human lipopolysaccharide (LPS)‐matured moDCs and allogeneic naive CD4+ T cells, we show that inhibition of mTOR by the immunosuppressive drug rapamycin reduced moDC maturation and promoted Th2 skewing. Next, we investigated whether antigens from helminth parasites, the strongest natural inducers of Th2 responses, modulate moDCs via the mTOR pathway. In contrast to rapamycin, neither Schistosoma mansoni‐soluble egg antigens (SEA) nor its major immunomodulatory component omega‐1 affected the phosphorylation of S6 kinase (S6K) and 4E‐binding protein 1 (4E‐BP1), downstream targets of mTORC1. Finally, we found that the effects of rapamycin and SEA/omega‐1 on Th2 skewing were additive, suggesting two distinct underlying molecular mechanisms. We conclude that conditioning human moDCs to skew immune responses towards Th2 can be achieved via an mTOR‐dependent and ‐independent pathway triggered by rapamycin and helminth antigens, respectively.
Self-assembly of hierarchical MoSx/CNT nanocomposites (2<x<3): towards high performance anode materials for lithium ion batteries
Authors: Shi Yumeng , Wang Ye , Wong Jen It , Tan Alex Yuan Sheng , Hsu Chang-Lung , Li Lain-Jong , Lu Yi-Chun , Yang Hui Ying
Published: July 2013

Two dimension (2D) layered molybdenum disulfide (MoS2) has emerged as a promising candidate for the anode material in lithium ion batteries (LIBs). Herein, 2D MoSx (2 ≤ x ≤ 3) nanosheet-coated 1D multiwall carbon nanotubes (MWNTs) nanocomposites with hierarchical architecture were synthesized via a high-throughput solvent thermal method under low temperature at 200°C. The unique hierarchical nanostructures with MWNTs backbone and nanosheets of MoSx have significantly promoted the electrode performance in LIBs. Every single MoSx nanosheet interconnect to MWNTs centers with maximized exposed electrochemical active sites, which significantly enhance ion diffusion efficiency and accommodate volume expansion during the electrochemical reaction. A remarkably high specific capacity (i.e., > 1000 mAh/g) was achieved at the current density of 50 mA g−1, which is much higher than theoretical numbers for either MWNTs or MoS2along (~372 and ~670 mAh/g, respectively). We anticipate 2D nanosheets/1D MWNTs nanocomposites will be promising materials in new generation practical LIBs.
CD4+ but not CD8+ T cells revert the impaired emotional behavior of immunocompromised RAG-1-deficient mice
Authors: Rattazzi L , Piras G , Ono M , Deacon R , Pariante C M , D'Acquisto F
Published: July 2013

An imbalanced immune system has long been known to influence a variety of mood disorders including anxiety, obsessive-compulsive disorders and depression. In this study, we sought to model the impact of an immunocompromised state on these emotional behaviors using RAG-1−/− mice, which lack T and B cells. We also investigated the relative contribution of CD4+ or CD8+ T cells to these manifestations using RAG-1−/−/OT-II and RAG-1−/−/OT-I transgenic mice, respectively. Our results show that RAG-1−/− mice present a significant increase in digging and marble-burying activities compared with wild-type mice. Surprisingly, these anxiety-like behaviors were significantly reverted in RAG-1−/−/OT-II but not RAG-1−/−/OT-I transgenic mice. Immunodepletion experiments with anti-CD4 or anti-CD8 in C57/BL6 mice or repopulation studies in RAG-1−/− mice did not reproduce these findings. Microarray analysis of the brain of RAG-1−/− and RAG-1−/−/OT-II mice revealed a significantly different gene fingerprint, with the latter being more similar to wild-type mice than the former. Further analysis revealed nine main signaling pathways as being significantly modulated in RAG-1−/− compared with wild-type mice. Taken together, these results suggest that life-long rather than transient immunodeficient conditions influence the emotional behaviors in mice. Most interestingly, these effects seem to correlate with a specific absence of CD4+ rather than CD8+ T cells. Validation of these findings in man might provide new clues on the mechanism by which early life immune modulation might impact mood response in adults and provide a further link between immune and emotional well-being.
Random walks on non-homogenous weighted Koch networks
Authors: Dai Meifeng , Li Xingyi , Xi Lifeng
Published: July 2013

In this paper, we introduce new models of non-homogenous weighted Koch networks on real traffic systems depending on the three scaling factors r1,r2,r3∈(0,1). Inspired by the definition of the average weighted shortest path (AWSP), we define the average weighted receiving time (AWRT). Assuming that the walker, at each step, starting from its current node, moves uniformly to any of its neighbors, we show that in large network, the AWRT grows as power-law function of the network order with the exponent, represented by θ(r1,r2,r3)=log4(1+r1+r2+r3). Moreover, the AWSP, in the infinite network order limit, only depends on the sum of scaling factors r1,r2,r3.
Measuring 8–250 ps short pulses using a high-speed streak camera on kilojoule, petawatt-class laser systems
Authors: Qiao J. , Jaanimagi P. A. , Boni R. , Bromage J. , Hill E.
Published: July 2013

Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a more-uniform streak image and enables one to characterize space-charge-induced pulse-broadening effects.
Three-dimensional numerical simulations of magnetohydrodynamic flow around a confined circular cylinder under low, moderate, and strong magnetic fields
Authors: Kanaris Nicolas , Albets Xavier , Grigoriadis Dimokratis , Kassinos Stavros
Published: July 2013

This paper presents three-dimensional direct numerical simulations of liquid metal flow around a circular cylinder placed symmetrically in a rectangular duct, under a wide range of magnetic field intensities. Results are presented for values of the Hartmann number (based on the duct width) in the range of 0 ⩽ Ha ⩽ 1120, and the Reynolds number (based on the cylinder diameter and centerline velocity) in the range 0 ⩽ Rec ⩽ 5000. The generated flow regimes and the associated critical values of parameters are investigated in detail through full three-dimensional simulations. The effect of the magnetic field on the wake structure is discussed in relation to the possible mechanisms for the generation or suppression of vortices, and to previous attempts to model magnetohydrodynamic flows using simplified two-dimensional models. Present results reveal a non-monotonic dependance of the critical Reynolds number for the onset of vortex shedding, with respect to the Hartmann number. For certain combinations of Ha and Re values, this work confirms the onset of a new flow regime, the existence of which has been recently suggested based on quasi-two-dimensional simulations. Unexpectedly, the spanwise distribution of the force coefficients along the cylinder is found to become more three-dimensional with increasing Ha. Furthermore, the three-dimensional nature of the present simulations reveals additional counter-intuitive features of the new regime that could not possibly had been captured by quasi-two-dimensional models. One such feature, shown here for the first time, is an increase in the flow unsteadiness with increasing intensity of the magnetic field.
Chemical selective microstructural analysis of thin film using resonant x-ray reflectivity
Authors: Nayak Maheswar , Lodha G. S.
Published: July 2013

Strong modulations of the reflected x-ray intensities near the respective absorption edges of the constituent materials promise to determine layer composition of thin film structures along with spectroscopic like information. Near the absorption edge, the orders of magnitude more contrast beyond the pure electron density distributions of materials find an approach to overcome the low density difficulty of the conventional x-ray reflectivity technique. These aspects are explained by experimental studies on partially decomposed boron nitride thin films. Chemical composition profile is determined from free surface to the embedded buried layer with depth resolution in nanometer scale. The results of resonant reflectivity for chemical analysis are correlated with depth dependent x-ray photo electron spectroscopy.
Scanning probe microscope simulator for the assessment of noise in scanning probe microscopy controllers
Authors: Wutscher T. , Niebauer J. , Giessibl F. J.
Published: July 2013

We present an electronic circuit that allows to calibrate and troubleshoot scanning probe microscopy (SPM) controllers with respect to their noise performance. The control signal in an SPM is typically highly nonlinear—the tunneling current in scanning tunneling microscopy (STM) varies exponentially with distance. The exponential current-versus-voltage characteristics of diodes allow to model the current dependence in STM. Additional inputs allow to simulate the effects of external perturbations and the reactions of the control electronics. We characterized the noise performance of the feedback controller using the apparent topography roughness of recorded images. For a comparison of different STM controllers, an optimal gain parameter was determined by exploring settling times through a rectangular perturbation signal. We used the circuit to directly compare the performance of two types of SPM controllers used in our laboratory.
Predicting the behavior of a chaotic pendulum with a variable interaction potential
Authors: Tran Vy , Brost Eric , Johnston Marty , Jalkio Jeff
Published: July 2013

The behavior of a chaotic physical pendulum is significantly modified through the addition of a magnetic interaction. The extended behavior is studied through identifying distinct characteristics in the Poincaré sections and turning point maps of the systems. The validity of our model is shown through simulated bifurcations generated from coefficients estimated at a number of different frequencies. These simulated bifurcations also demonstrate that coefficients estimated at one frequency can be used to predict the behavior of the system at a different drive frequency. A quantitative measure of the correlation dimension shows that the simulated Poincaré diagrams are in good agreement with experiment and theory. Possible sources of bias in modeled systems are identified.
Predicting alloy vibrational mode properties using lattice dynamics calculations, molecular dynamics simulations, and the virtual crystal approximation
Authors: Larkin Jason M. , McGaughey Alan J. H.
Published: July 2013

The virtual crystal (VC) approximation for mass disorder is evaluated by examining two model alloy systems: Lennard-Jones argon and Stillinger-Weber silicon. In both material systems, the perfect crystal is alloyed with a heavier mass species up to equal concentration. The analysis is performed using molecular dynamics simulations and lattice dynamics calculations. Mode frequencies and lifetimes are first calculated by treating the disorder explicitly and under the VC approximation, with differences found in the high-concentration alloys at high frequencies. Notably, the lifetimes of high-frequency modes are underpredicted using the VC approximation, a result we attribute to the neglect of higher-order terms in the model used to include point-defect scattering. The mode properties are then used to predict thermal conductivity under the VC approximation. For the Lennard-Jones alloys, where high-frequency modes make a significant contribution to thermal conductivity, the high-frequency lifetime underprediction leads to an underprediction of thermal conductivity compared to predictions from the Green-Kubo method, where no assumptions about the thermal transport are required. Based on observations of a minimum mode diffusivity, we propose a correction that brings the VC approximation thermal conductivities into better agreement with the Green-Kubo values. For the Stillinger-Weber alloys, where the thermal conductivity is dominated by low-frequency modes, the high-frequency lifetime underprediction does not affect the thermal conductivity prediction and reasonable agreement is found with the Green-Kubo values.
Communication: Two-determinant mixing with a strong-correlation density functional
Authors: Becke Axel D.
Published: July 2013

In recent papers [A. D. Becke, J. Chem. Phys. 138, 074109 (2013)10.1063/1.4790598; A. D. Becke, J. Chem. Phys. 138, 161101 (2013)10.1063/1.4802982], a density functional for strong correlations in quantum chemistry was introduced. The functional is designed to capture molecular dissociation limits using symmetry-restricted orbitals. Here we demonstrate that the functional describes, with good accuracy, two-determinant multi-reference states. The examples of this work involve 50/50 mixing of symmetry-equivalent Slater determinants at avoided crossings. We employ exactly-computed exchange and fractional spin-orbital occupancies. The connection with dissociated systems and single-determinant reference states is explained.
An explanation for invalidity of working currents' derating on improving light-emitting diode devices' reliability
Authors: Liu Lilin , Yang Jianfu , Teng Dongdong , Qi Shan , Wang Gang
Published: July 2013

Derating of the working current level does not work for improving GaN-based light-emitting diode (LED) devices' reliability. The present work demonstrates that it is not the levels but the specific components of the applied electrical currents weighing more on LEDs' degradation. Existing defects are sources for tunneling currents and Shockley-Read-Hall (SRH) non-radiative recombination current, and the component of tunneling currents and SRH non-radiative recombination current in the applied electrical current will in turn induce fast increase of defect density. The current component from electron tunneling to deep levels in the vicinity of mixed/screw dislocations will affect more on LEDs' degradation than other components, such as heavy-hole tunneling via intermediate state. In a whole, the overflow leakage current from the active region and Auger recombination currents in the applied electrical current will generate positive effects to alleviate LEDs' degradation.
Tailoring femtosecond laser pulse filamentation using plasma photonic lattices
Authors: Suntsov Sergiy , Abdollahpour Daryoush , Papazoglou Dimitrios G. , Panagiotopoulos Paris , Couairon Arnaud , Tzortzakis Stelios
Published: July 2013

We demonstrate experimentally that by using transient plasma photonic lattices, the attributes of intense femtosecond laser filaments, such as peak intensity and length, can be dynamically controlled. The extended plasma lattice structure is generated using two co-propagating non-diffracting intense Bessel beams in water. The use of such transient lattice structures to control the competition between linear and nonlinear effects involved in filamentation opens the way for extensive control of the filamentation process.
Amorphous thin film TaWSiC as a diffusion barrier for copper interconnects
Authors: Wongpiya Ranida , Ouyang Jiaomin , Roy Kim Taeho , Deal Michael , Sinclair Robert , Nishi Yoshio , Clemens Bruce
Published: July 2013

A very thin and amorphous TaWSiC film with relatively low resistivity of 233 μΩ·cm was studied for its effectiveness as a diffusion barrier for copper interconnects. A 5 nm thick TaWSiC barrier effectively prevents copper diffusion and maintains structural integrity up to an annealing temperature of at least 550 °C, with copper silicide formation observed at 650 °C. In comparison, a barrier of 5 nm of nanocrystalline Ta already fails at 550 °C. Being very thin and amorphous, while having low resistivity and good thermal stability, are crucial properties of a good diffusion barrier for future technology, and this film meets these requirements.
Relationship between Gilbert damping and magneto-crystalline anisotropy in a Ti-buffered Co/Ni multilayer system
Authors: Song Hyon-Seok , Lee Kyeong-Dong , Sohn Jeong-Woo , Yang See-Hun , Parkin Stuart S. P. , You Chun-Yeol , Shin Sung-Chul
Published: July 2013

The relationship between Gilbert damping and magneto-crystalline anisotropy is studied here using an all-optical method in a perpendicular Co/Ni multilayer system by varying the Ti-buffer thickness. As the Ti-buffer thickness increases, the magneto-crystalline anisotropy is enhanced. The time-resolved Kerr signal of each sample is well described by its own intrinsic Gilbert damping constant in a wide range of the external magnetic field. Interestingly, we find that Gilbert damping constants increase linearly from 0.021 to 0.036 when the magneto-crystalline anisotropy of the samples varies from 2.4 to 3.4 Merg/cm3. Such a linear relationship implies that the spin-orbit interaction is the main source of the damping process through spin-lattice relaxation in our system.
Scaling size of the interplay between quantum confinement and surface related effects in nanostructured silicon
Authors: Seguini G. , Castro C. , Schamm-Chardon S. , BenAssayag G. , Pellegrino P. , Perego M.
Published: July 2013

Si nanocrystals (NCs) embedded in a SiO2 matrix provide an exemplar curved nanostructured interface to evidence the competition between surface states and quantum confinement (QC) effects. The study of the energy band alignment as a function of NCs size (<5 nm) clarifies their interplay and identifies, with subnanometric resolution, three different regimes. Primarily QC affects the conduction band, then surface effects pin the conduction states, and finally QC starts to modify the valence band. A way to study how different nanoscale configurations compete with pure quantum properties is established.
A mechanism for induction of a hypoxic response by vaccinia virus
Authors: Mazzon Michela , Peters Nicholas E. , Loenarz Christoph , Krysztofinska Ewelina M. , Ember Stuart W. J. , Ferguson Brian J. , Smith Geoffrey L.
Published: July 2013

Viruses have evolved sophisticated strategies to exploit host cell function for their benefit. Here we show that under physiologically normal oxygen levels (normoxia) vaccinia virus (VACV) infection leads to a rapid stabilization of hypoxia-inducible factor (HIF)-1α, its translocation into the nucleus and the activation of HIF-responsive genes, such as vascular endothelial growth factor (VEGF), glucose transporter-1, and pyruvate dehydrogenase kinase-1. HIF-1α stabilization is mediated by VACV protein C16 that binds the human oxygen sensing enzyme prolyl-hydroxylase domain containing protein (PHD)2 and thereby inhibits PHD2-dependent hydroxylation of HIF-1α. The binding between C16 and PHD2 is direct and specific, and ectopic expression of C16 alone induces transcription of HIF-1α responsive genes. Conversely, a VACV strain lacking the gene for C16,
C16L
, is unable to induce HIF-1α stabilization. Interestingly, the N-terminal region of C16 is predicted to have a PHD2-like structural fold but lacks the catalytic active site residues of PHDs. The induction of a hypoxic response by VACV is reminiscent of the biochemical consequences of solid tumor formation, and illustrates a poxvirus strategy for manipulation of cellular gene expression and biochemistry.
Activation loop phosphorylation of a protein kinase is a molecular marker of organelle size that dynamically reports flagellar length
Authors: Cao Muqing , Meng Dan , Wang Liang , Bei Shuqing , Snell William J. , Pan Junmin
Published: July 2013

Specification of organelle size is crucial for cell function, yet we know little about the molecular mechanisms that report and regulate organelle growth and steady-state dimensions. The biflagellated green alga
Chlamydomonas
requires continuous-length feedback to integrate the multiple events that support flagellar assembly and disassembly and at the same time maintain the sensory and motility functions of the organelle. Although several length mutants have been characterized, the requisite molecular reporter of length has not been identified. Previously, we showed that depletion of
Chlamydomonas
aurora-like protein kinase CALK inhibited flagellar disassembly and that a gel-shift–associated phosphorylation of CALK marked half-length flagella during flagellar assembly. Here, we show that phosphorylation of CALK on T193, a consensus phosphorylation site on the activation loop required for kinase activity, is distinct from the gel-shift–associated phosphorylation and is triggered when flagellar shortening is induced, thereby implicating CALK protein kinase activity in the shortening arm of length control. Moreover, CALK phosphorylation on T193 is dynamically related to flagellar length. It is reduced in cells with short flagella, elevated in the long flagella mutant,
lf4,
and dynamically tracks length during both flagellar assembly and flagellar disassembly in WT, but not in
lf4
. Thus, phosphorylation of CALK in its activation loop is implicated in the disassembly arm of a length feedback mechanism and is a continuous and dynamic molecular marker of flagellar length during both assembly and disassembly.
Evidence for a water system transition beneath Thwaites Glacier, West Antarctica
Authors: Schroeder Dustin M. , Blankenship Donald D. , Young Duncan A.
Published: July 2013

Thwaites Glacier is one of the largest, most rapidly changing glaciers on Earth, and its landward-sloping bed reaches the interior of the marine West Antarctic Ice Sheet, which impounds enough ice to yield meters of sea-level rise. Marine ice sheets with landward-sloping beds have a potentially unstable configuration in which acceleration can initiate or modulate grounding-line retreat and ice loss. Subglacial water has been observed and theorized to accelerate the flow of overlying ice dependent on whether it is hydrologically distributed or concentrated. However, the subglacial water systems of Thwaites Glacier and their control on ice flow have not been characterized by geophysical analysis. The only practical means of observing these water systems is airborne ice-penetrating radar, but existing radar analysis approaches cannot discriminate between their dynamically critical states. We use the angular distribution of energy in radar bed echoes to characterize both the extent and hydrologic state of subglacial water systems across Thwaites Glacier. We validate this approach with radar imaging, showing that substantial water volumes are ponding in a system of distributed canals upstream of a bedrock ridge that is breached and bordered by a system of concentrated channels. The transition between these systems occurs with increasing surface slope, melt-water flux, and basal shear stress. This indicates a feedback between the subglacial water system and overlying ice dynamics, which raises the possibility that subglacial water could trigger or facilitate a grounding-line retreat in Thwaites Glacier capable of spreading into the interior of the West Antarctic Ice Sheet.
Climate, fishing, and fluctuations of sardine and anchovy in the California Current
Authors: Lindegren Martin , Checkley David M. , Rouyer Tristan , MacCall Alec D. , Stenseth Nils Chr.
Published: July 2013

Since the days of Elton, population cycles have challenged ecologists and resource managers. Although the underlying mechanisms remain debated, theory holds that both density-dependent and density-independent processes shape the dynamics. One striking example is the large-scale fluctuations of sardine and anchovy observed across the major upwelling areas of the world. Despite a long history of research, the causes of these fluctuations remain unresolved and heavily debated, with significant implications for fisheries management. We here model the underlying causes of these fluctuations, using the California Current Ecosystem as a case study, and show that the dynamics, accurately reproduced since A.D. 1661 onward, are explained by interacting density-dependent processes (i.e., through species-specific life-history traits) and climate forcing. Furthermore, we demonstrate how fishing modifies the dynamics and show that the sardine collapse of the 1950s was largely unavoidable given poor recruitment conditions. Our approach provides unique insight into the origin of sardine–anchovy fluctuations and a knowledge base for sustainable fisheries management in the California Current Ecosystem and beyond.
Tumor-derived hydrogen sulfide, produced by cystathionine-β-synthase, stimulates bioenergetics, cell proliferation, and angiogenesis in colon cancer
Authors: Szabo Csaba , Coletta Ciro , Chao Celia , Módis Katalin , Szczesny Bartosz , Papapetropoulos Andreas , Hellmich Mark R.
Published: July 2013

The physiological functions of hydrogen sulfide (H2S) include vasorelaxation, stimulation of cellular bioenergetics, and promotion of angiogenesis. Analysis of human colon cancer biopsies and patient-matched normal margin mucosa revealed the selective up-regulation of the H2S-producing enzyme cystathionine-β-synthase (CBS) in colon cancer, resulting in an increased rate of H2S production. Similarly, colon cancer-derived epithelial cell lines (HCT116, HT-29, LoVo) exhibited selective CBS up-regulation and increased H2S production, compared with the nonmalignant colonic mucosa cells, NCM356. CBS localized to the cytosol, as well as the mitochondrial outer membrane. ShRNA-mediated silencing of CBS or its pharmacological inhibition with aminooxyacetic acid reduced HCT116 cell proliferation, migration, and invasion; reduced endothelial cell migration in tumor/endothelial cell cocultures; and suppressed mitochondrial function (oxygen consumption, ATP turnover, and respiratory reserve capacity), as well as glycolysis. Treatment of nude mice with aminooxyacetic acid attenuated the growth of patient-derived colon cancer xenografts and reduced tumor blood flow. Similarly, CBS silencing of the tumor cells decreased xenograft growth and suppressed neovessel density, suggesting a role for endogenous H2S in tumor angiogenesis. In contrast to CBS, silencing of cystathionine-γ-lyase (the expression of which was unchanged in colon cancer) did not affect tumor growth or bioenergetics. In conclusion, H2S produced from CBS serves to (i) maintain colon cancer cellular bioenergetics, thereby supporting tumor growth and proliferation, and (ii) promote angiogenesis and vasorelaxation, consequently providing the tumor with blood and nutritients. The current findings identify CBS-derived H2S as a tumor growth factor and anticancer drug target.