bluuebunny/crossref_metadata_2025 huggingface dataset:
Early menarche predicts increased depressive symptoms and cortisol levels in Quebec girls ages 11 to 13
Authors: Trépanier Lyane , Juster Robert-Paul , Marin Marie-France , Plusquellec Pierrich , Francois Nathe , Sindi Shireen , Wan Nathalie , Findlay Helen , Schramek Tania , Andrews Julie , Corbo Vincent , Dedovic Katarina , Lupien Sonia
Published: November 2013

Earlier age of menarche is believed to confer greater vulnerability to depressive symptoms via increased reactivity to stressors associated with adolescence. In this longitudinal study, we measured depressive symptoms and salivary cortisol levels in 198 boys and 142 girls between the ages of 11 and 13 tested four times during Grade 7 as they transitioned from elementary school to secondary school as per Quebec's education system. Results showed that girls who had already reached menarche before starting secondary school had significantly higher depressive symptoms and salivary cortisol levels across the school year in comparison to girls who had not reached menarche, who in turn presented higher depressive scores than boys. When we divided menarcheal girls as a function of menarcheal timing in subanalyses, we found that girls with early menarche presented consistently elevated depressive symptoms across the school year while girls with on-time menarche presented transient depressive symptoms but no differences in salivary cortisol levels. Collectively, these results show that early menarche is associated with high depressive symptoms and cortisol levels in adolescent girls. This developmental milestone may render girls more vulnerable to environmental stressors and therefore represents a critical period to intervene to promote mental health.
Blunted feedback processing during risky decision making in adolescents with a parental history of substance use disorders
Authors: Euser Anja S. , Greaves-Lord Kirstin , Crowley Michael J. , Evans Brittany E. , Huizink Anja C. , Franken Ingmar H. A.
Published: November 2013

Risky decision making, a hallmark phenotype of substance use disorders (SUD), is thought to be associated with deficient feedback processing. Whether these aberrations are present prior to SUD onset or reflect merely a consequence of chronic substance use on the brain remains unclear. The present study investigated whether blunted feedback processing during risky decision making reflects a biological predisposition to SUD. We assessed event-related potentials elicited by positive and negative feedback during performance of a modified version of the Balloon Analogue Risk Task (BART) among high-risk adolescents with a parental history of SUD (HR;n= 61) and normal-risk controls (NR;n= 91). HR males made significantly more risky and faster decisions during the BART than did NR controls. Moreover, HR adolescents showed significantly reduced P300 amplitudes in response to both positive and negative feedback as compared to NR controls. These differences were not secondary to prolonged substance use exposure. Results are discussed in terms of feedback-specific processes. Reduced P300 amplitudes in the BART may reflect poor processing of feedback at the level of overall salience, which may keep people from effectively predicting the probability of future gains and losses. Though conclusions are tentative, blunted feedback processing during risky decision making may represent a promising endophenotypic vulnerability marker for SUD.
Maturing out of alcohol involvement: Transitions in latent drinking statuses from late adolescence to adulthood
Authors: Lee Matthew R. , Chassin Laurie , Villalta Ian K.
Published: November 2013

Research has shown a developmental process of “maturing out” of alcohol involvement beginning in young adulthood, but the precise nature of changes characterizing maturing out is unclear. We used latent transition analysis to investigate these changes in a high-risk sample from a longitudinal study of familial alcoholism (N = 844; 51% children of alcoholics; 53% male, 71% non-Hispanic Caucasian, 27% Hispanic). Analyses classified participants into latent drinking statuses during late adolescence (ages 17–22), young adulthood (ages 23–28), and adulthood (ages 29–40), and characterized transitions among these statuses over time. The resulting four statuses were abstainers, low-risk drinkers who typically drank less than weekly and rarely binged or showed drinking problems, moderate-risk drinkers who typically binged less than weekly and showed moderate risk for drinking problems, and high-risk drinkers who typically binged at least weekly and showed high risk for drinking problems. Maturing out between late adolescence and young adulthood was most common among initial high-risk drinkers, but they typically declined to moderate-risk drinking rather than to nonrisky drinking statuses. This suggests that the developmental phenomenon of maturing out pertains primarily to relatively high-risk initial drinkers and that many high-risk drinkers who mature out merely reduce rather than eliminate their risky drinking.
Test–retest reliability and sensitivity to change of the dimensional anxiety scales for DSM-5
Authors: Knappe Susanne , Klotsche Jens , Heyde Franziska , Hiob Sarah , Siegert Jens , Hoyer Jürgen , Strobel Anja , LeBeau Richard T. , Craske Michelle G. , Wittchen Hans-Ulrich , Beesdo-Baum Katja
Published: November 2013

Objective

This article reports on the test–retest reliability and sensitivity to change of a set of brief dimensional self-rating questionnaires for social anxiety disorder (SAD-D), specific phobia (SP-D), agoraphobia (AG-D), panic disorder (PD-D), and generalized anxiety disorder (GAD-D), as well as a general cross-cutting anxiety scale (Cross-D), which were developed to supplement categorical diagnoses in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5).

Methods

The German versions of the dimensional anxiety scales were administered to 218 students followed up approximately 2 weeks later (Study 1) and 55 outpatients (23 with anxiety diagnoses) followed-up 1 year later (Study 2). Probable diagnostic status in students was determined by the DIA-X/M-CIDI stem screening-questionnaire (SSQ). In the clinical sample, Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) diagnoses were assessed at Time 1 using the DIA-X/M-CIDI. At Time 2, the patient-version of the Clinical Global Impression—Improvement scale (CGI-I) was applied to assess change.

Results

Good psychometric properties, including high test–retest reliability, were found for the dimensional scales except for SP-D. In outpatients, improvement at Time 2 was associated with significant decrease in PD-D, GAD-D, and Cross-D scores.

Discussion

Major advantages of the scales include that they are brief, concise, and based on a consistent template to measure the cognitive, physiological, and behavioral symptoms of fear and anxiety. Further replication in larger samples is needed. Given its modest psychometric properties, SP-D needs refinement.

Conclusion

Increasing evidence from diverse samples suggests clinical utility of the dimensional anxiety scales.
Turns, tropes and terminology. Toward an interspecies ‘(inter)social’
Authors: Argent Gala
Published: November 2013

All living creatures exist with others in relationships – networks of ecological, biological, psychological and social interactions – that are ongoing and meaningful, and at some level affect their animate neighbours. This point seems so self-evident that it should not need stating. Yet in many instances both archaeologists and scholars within other disciplines remain mired within an anthropocentric metanarrative which serves the purpose of limiting the study of these relationships either to the human use, or to the (human) cultural construction, of non-human animals. That is changing. In arguing that a ‘shift . . . of emphasis to the live animal as an autonomous being with its own agency and even its known perspective on other species is long overdue’ (p. 116), Nick Overton and Yannis Hamiliakis offer a valuable contribution toward refining the ongoing archaeological re-examination of the potential gestalt of the human–animal social interface.
Do the swans deceive us all?
Authors: Boyd Brian
Published: November 2013

A theoretically nuanced human–animal studies now stands at the forefront of many academic disciplines. The ‘theoretical lag’ characteristic of archaeology means that a subject largely reliant on the remains of humans and animals, and their associated material residues, lies lacking in theoretical sophistication.
Tooth-beads, antlers, nuts and fishes. Examples of social bioarchaeology
Authors: Larsson Lars
Published: November 2013

I am sitting at my computer with a purring cat resting its head against the keyboard – a real animal–animal situation and a reciprocal relationship. For 15 years, my wife and I looked after horses that our children had left behind when they moved off into the world. The reason was that the horses belonged, in their own way, to the extended family. So I have no difficulty understanding what Overton and Hamilakis call ‘social zooarchaeology’. As a pet owner who has personally observed the individuality of animals – from hens to horses – I have no problem accepting their view that animals are individuals, something that my urban colleagues often question. When discussing with hunters who have specialized for many years in one type of hunting, they can describe how different individuals in flocks – for example, among red deer and moose – can behave. They spend many hours moving in the terrain and observe the different animal species, not to hunt them but to acquire further knowledge about the animals, sometimes to find out which animals should later be culled, but often only for the sheer pleasure of feeling a kind of relationship between themselves and the animals they follow.
On whooper swans, social zooarchaeology and traditional zooarchaeologyʼs weight
Authors: Mannermaa Kristiina
Published: November 2013

The article by Overton and Hamilakis challenges so-called traditional zooarchaeology and works as a manifesto for a new social zooarchaeology, as the authors call it. This new social zooarchaeology moves beyond the thinking of animals as (purely) resources and instead reinstates their position as sentient and autonomous agents. The approach is fresh and evidence-based (e.g. Robb 2010). The sites and bone materials used as examples come from Late Mesolithic Denmark: the Ertebølle site Aggersund in Jutland and Ertebølle Grave 8 at Vedbæk, Sjælland. Both sites were excavated and analysed many years ago, but the bone material has been reanalysed and interpreted for this study.
Escaping from the pen?
Authors: Pluciennik Mark
Published: November 2013

First of all, congratulations to Nick Overton and Yannis Hamilakis for an excellent and stimulating paper, made all the better for including two considered and rich case studies. Though in no way an animal-bone specialist, I find myself in general agreement with their approach, which attempts to persuade zooarchaeologists of the value of engaging further with particular trends within theory in archaeology (and other disciplines) from the last decade or so. It is with the implications of relational archaeologies that I particularly wish to engage: I concur with the authors that zooarchaeology (and other subfields), as well as archaeology more generally, could benefit from challenges to anthropocentrism, whether expressed in ontological or other forms, and ultimately produce more holistic as well as more diverse pasts. My comments are thus more an exploration of some of the issues raised in this paper than a commentary upon the contents per se.
A multi-species archaeology
Authors: Hamilakis Yannis , Overton Nick J.
Published: November 2013

These are interesting times for the exploration of the relationships between humans and other animals. The ‘animal turn’ is in full swing in a number of disciplines; anthropologists have started talking of the emergence of a multi-species ethnography (Kirksey and Helmreich 2010); and even archaeologists have, somehow hesitantly, started contributing to wider discussions within animal studies (e.g. see the recent – 2013 – special issue of the journalSociety and animalsdevoted to archaeology; and Harris and Hamilakis, in press). Another indication that things are changing is the overwhelmingly positive response to our ‘manifesto’ by most commentators, who have offered many valuable thoughts which expand our reflections in many and interesting directions: we are grateful. Rather than trying to comment on every single point raised in this discussion, which in any case would have been impossible in the space provided, we have selected instead a couple of issues that, we hope, readers will find engaging and fruitful.
Doors to the dead. The power of doorways and thresholds in Viking Age Scandinavia
Authors: Eriksen Marianne Hem
Published: November 2013

Mortuary practices could vary almost indefinitely in the Viking Age. Within a theoretical framework of ritualization and architectural philosophy, this article explores how doors and thresholds were used in mortuary practice and ritual behaviour. The door is a deep metaphor for transition, transformation and liminality. It is argued that Viking Age people built ‘doors to the dead’ of various types, such as freestanding portals, causewayed ring-ditches or thresholds to grave mounds; or on occasion even buried their dead in the doorway. The paper proposes that the ritualized doors functioned in three ways: they created connections between the dead and the living; they constituted boundaries and thresholds that could possibly be controlled; and they formed between-spaces, expressing liminality and, conceivably, deviance. Ultimately, the paper underlines the profound impact of domestic architecture on mortuary practice and ritual behaviour in the Viking Age.
QUASICONVEXITY OF BANDS IN HYPERBOLIC 3-MANIFOLDS
Authors: BOWDITCH BRIAN H.
Published: November 2013

Let$M$be a complete hyperbolic 3-manifold homotopy equivalent to a compact surface$\Sigma $. Let$\Phi $be a proper subsurface of$\Sigma $, whose boundary is sufficiently short in$M$. We show that the union of all Margulis tubes and cusps homotopic into$\Phi $lifts to a uniformly quasiconvex subset of hyperbolic 3-space.
USING IDEALS TO PROVIDE A UNIFIED APPROACH TO UNIQUELY CLEAN RINGS
Authors: HIREMATH V. A. , HEGDE SHARAD
Published: November 2013

In this article, we introduce the notion of the uniquely $I$-clean ring and show that, if $R$ is a ring and $I$ is an ideal of $R$ then $R$ is uniquely $I$-clean if and only if ($R/ I$ is Boolean and idempotents lift uniquely modulo $I$) if and only if (for each $a\in R$ there exists a central idempotent $e\in R$ such that $e- a\in I$ and $I$ is idempotent-free). We examine when ideal extension is uniquely clean relative to an ideal. Also we obtain conditions on a ring $R$ and an ideal $I$ of $R$ under which uniquely $I$-clean rings coincide with uniquely clean rings. Further we prove that a ring $R$ is uniquely nil-clean if and only if ($N(R)$ is an ideal of $R$ and $R$ is uniquely $N(R)$-clean) if and only if $R$ is both uniquely clean and nil-clean if and only if ($R$ is an abelian exchange ring with $J(R)$ nil and every quasiregular element is uniquely clean). We also show that $R$ is a uniquely clean ring such that every prime ideal of $R$ is maximal if and only if $R$ is uniquely nil-clean ring and $N(R)= {\mathrm{Nil} }_{\ast } (R)$.
ON THE GROUP INVERSE FOR THE SUM OF MATRICES
Authors: BU CHANGJIANG , ZHOU XIUQING , MA LIANG , ZHOU JIANG
Published: November 2013

Let${ \mathbb{K} }^{m\times n} $denote the set of all$m\times n$matrices over a skew field$ \mathbb{K} $. In this paper, we give a necessary and sufficient condition for the existence of the group inverse of$P+ Q$and its representation under the condition$PQ= 0$, where$P, Q\in { \mathbb{K} }^{n\times n} $. In addition, in view of the natural characters of block matrices, we give the existence and representation for the group inverse of$P+ Q$and$P+ Q+ R$under some conditions, where$P, Q, R\in { \mathbb{K} }^{n\times n} $.
Shared decision making in palliative cancer care: a literature review
Authors: Feuz C.
Published: November 2013

Background

Patients require information to make informed decisions and consent to medical treatment. Shared decision making (SDM) is a methodology that promotes a patient-centred approach to informed consent and demonstrates respect for autonomy

Purpose

The purpose of this paper is to critically review the legal and ethical issues relevant to Canadian and UK informed consent and SDM practices and how these processes relate to current palliative care practices, with a particular emphasis on radiation therapy.

Methodology

A review of the English literature from 2003 to 2013 was performed using the databases PubMed (NML), OVID Medline and Google Scholar.

Results and Conclusions

The literature identifies that palliative cancer patients desire the opportunity to be involved with decision-making discussions, which has shown to increase knowledge and result in better health-related outcomes. However, ethical and legal issues regarding the practicality of including this patient population in SDM discussions raises questions about validity of consent. For SDM to be considered a valid methodology to obtain informed consent, open and honest communication between the patient and multidisciplinary team is essential. Treatment options for palliative cancer patients are often complex and SDM allows healthcare professionals and patients to exchange information and negotiate feasible treatment options based on medical expertise and patient preferences.

Legal frameworks have defined current standards of practice for various healthcare professions, including radiation therapy. Radiation therapists, as members of the multidisciplinary team, are currently key contributors in providing information to patients regarding the radiotherapy process. Individuals working within advanced practice roles have the ability to develop skills once considered to be within medical domains and have begun to incorporate the delegated act of obtaining informed consent into practice which has shown to increase professional autonomy, accountability and improves patient-centred care.
Tapping the crowds for research funding
Authors: Weigmann Katrin
Published: November 2013

Scientists are exploring crowdfunding as a potential new source of cash for their research.
Identification of telomere-associated molecules by engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP)
Authors: Fujita Toshitsugu , Asano Yoshinori , Ohtsuka Junko , Takada Yoko , Saito Kazunobu , Ohki Rieko , Fujii Hodaka
Published: November 2013

Biochemical analysis of molecular interactions in specific genomic regions requires their isolation while retaining molecular interactions in vivo. Here, we report isolation of telomeres by engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) using a transcription activator-like (TAL) protein recognizing telomere repeats. Telomeres recognized by the tagged TAL protein were immunoprecipitated with an antibody against the tag and subjected to identification of telomere-binding molecules. enChIP-mass spectrometry (enChIP-MS) targeting telomeres identified known and novel telomere-binding proteins. The data have been deposited to the ProteomeXchange with identifier PXD000461. In addition, we showed that RNA associated with telomeres could be isolated by enChIP. Identified telomere-binding molecules may play important roles in telomere biology. enChIP using TAL proteins would be a useful tool for biochemical analysis of specific genomic regions of interest.
Determination of cocaine, its metabolites and pyrolytic products by LC-MS using a chemometric approach
Authors: Pereira Andrea Garcia , D'Avila Felipe Bianchini , Ferreira Pâmela C. Lukasewicz , Holler Marcelo Gatteli , Limberger Renata Pereira , Fröehlich Pedro Eduardo
Published: November 2013

A method to assay cocaine, its metabolites, pyrolytic products and adulterant levamisole was developed and validated by liquid chromatography-mass spectrometry (LC-MS) using a chemometric approach including a two-level factorial design and face-centered central composite design (FCCCD) to achieve the optimization.
A ratiometric and colorimetric luminescent thermometer over a wide temperature range based on a lanthanide coordination polymer
Authors: Cui Yuanjing , Zou Wenfeng , Song Ruijing , Yu Jiancan , Zhang Wenqian , Yang Yu , Qian Guodong
Published: November 2013

A lanthanide coordination polymer Tb0.957Eu0.043cpda was synthesized as a ratiometric and colorimetric luminescent thermometer.
RAM function is dependent on Kapβ2-mediated nuclear entry
Authors: Gonatopoulos-Pournatzis Thomas , Cowling Victoria H.
Published: November 2013

Eukaryotic gene expression is dependent on the modification of the first transcribed nucleotide of pre-mRNA by the addition of the 7-methylguanosine cap. The cap protects transcripts from exonucleases and recruits complexes which mediate transcription elongation, processing and translation initiation. The cap is synthesized by a series of reactions which link 7-methylguanosine to the first transcribed nucleotide via a 5′ to 5′ triphosphate bridge. In mammals, cap synthesis is catalysed by the sequential action of RNGTT (RNA guanylyltransferase and 5′-phosphatase) and RNMT (RNA guanine-7 methyltransferase), enzymes recruited to RNA pol II (polymerase II) during the early stages of transcription. We recently discovered that the mammalian cap methyltransferase is a heterodimer consisting of RNMT and the RNMT-activating subunit RAM (RNMT-activating mini-protein). RAM activates and stabilizes RNMT and thus is critical for cellular cap methylation and cell viability. In the present study we report that RNMT interacts with the N-terminal 45 amino acids of RAM, a domain necessary and sufficient for maximal RNMT activation. In contrast, smaller components of this RAM domain are sufficient to stabilize RNMT. RAM functions in the nucleus and we report that nuclear import of RAM is dependent on PY nuclear localization signals and Kapβ2 (karyopherin β2) nuclear transport protein.
Angular‐partitioned spin image descriptor for robust 3D facial landmark detection
Authors: Choi K.‐S. , Kim D.‐H.
Published: November 2013

Spin images have been widely used for representing local three‐dimensional (3D) shapes in 3D object recognition and 3D facial landmark detection. An improved spin image descriptor is proposed which enhances shape discrimination performance significantly over the spin image. By generating several sub‐spin images for angular‐partitioned subspaces, the description of unique angular features within local surfaces can be offered. The experimental results show that the proposed angular‐partitioned spin image enhances the localisation accuracy of facial landmarks by 47% and detection reliability by 33% as compared to the spin image.
Swap time‐aware garbage collection policy for NAND flash‐based swap system
Authors: Lin M.W. , Chen S.Y.
Published: November 2013

A swap time‐aware garbage collection (STGC) policy for the NAND flash‐based swap system is proposed, which focuses on reducing the cleaning cost and improving the degree of wear‐levelling. STGC calculates the cleaning index value of each block to select a victim block and the normalised value of the elapsed swap time of each valid page within the victim blocks to identify the hot valid page and cold valid page. Trace‐driven simulations with a synthetic trace show that the STGC outperforms the existing garbage collection policies.
Person re‐identification by multi‐statistics on pyramid of covariance matrices
Authors: Zeng Ming Yong , Wu Zemin , Tian Chang , Fu Yi , Zhang Feng Xia
Published: November 2013

A novel and efficient covariance‐based method for person re‐identification is proposed. The approach exploits three colourspaces and intensity gradients as covariance features and extracts multiple statistical feature vectors from the pyramid of region covariance matrices. The distance measure of the covariance pyramid is designed to be the weighted combination of four vectorised statistical features by cascading on the covariance pyramid. The method is compared with the state‐of‐the‐art methods using a benchmark dataset and is demonstrated to outperform other state‐of‐the‐art methods.
Parity‐check multiplicity in binary cyclic codes
Authors: Arul V. , Frost G. , Jung D.
Published: November 2013

Tests to determine the multiplicity of (1 + x) in a polynomial in 𝔽2[x] are provided. The primary application is to detect decode failure in binary BCH codes whose generator polynomial includes multiple factors of (1 + x).
Frequency comb from 500 Hz to 2 THz by optical rectification in zinc telluride
Authors: Hagmann M.J. , Henage T.E. , Azad A.K. , Taylor A.J. , Yarotski D.A.
Published: November 2013

Optical rectification of ultrafast laser pulses is widely used to generate THz radiation. Here, the microwave frequency comb generated by optical rectification with a ZnTe(100) crystal and a mode‐locked ultrafast laser has been measured, showing that the harmonics are at integer multiples of the pulse repetition rate of the laser (500 Hz). Strong correlations of the peak powers of the simultaneously measured THz spectrum and the measurements of the microwave frequency comb near 7.5 GHz suggest that they have a common origin.
High‐efficiency rectifier using composite right‐/left‐handed transmission line
Authors: Choi S. , Lim S.
Published: November 2013

A novel high‐efficiency rectifier using a composite right‐/left‐handed (CRLH) transmission line (TL) is proposed for 900 MHz wireless power transmission applications. The open‐ended CRLH TL stub replaces the bandpass filter (BPF) of a conventional rectifier and has a small size as compared to the traditional BPF. The open‐ended CRLH TL stub is designed to suppress the second and third harmonics and to match the fundamental frequency to 50 Ω impedance. The maximum RF‐to‐DC conversion efficiency of the proposed rectifier is 69.9% at an input power of 50 mW and a load of 1.8 kΩ. A design procedure based on the phase response of a CRLH TL is presented and validated by simulated and measurement results.
Thermal conductivity of bulk and nanowire InAs, AlN, and BeO polymorphs from first principles
Authors: Li Wu , Mingo Natalio
Published: November 2013

We compute the thermal conductivity of the alternative zincblende (ZB) and wurtzite (WZ) phases of InAs, AlN, and BeO. The bulk thermal conductivity of the ZB phase of BeO is predicted to be even higher than that of its WZ phase (the highest amongst all ceramics used in electronic technology). Our calculations agree well with the available experimental measurements for bulk ZB InAs, WZ AlN, WZ BeO, and WZ and ZB InAs nanowires, and we provide predictions for the remaining cases. The predicted good thermal conductor ZB BeO might have interesting applications in improved heat sinks for high performance semiconductor electronics.
Thermal transport in boron nitride nanotorus—towards a nanoscopic thermal shield
Authors: Loh G. C. , Baillargeat D.
Published: November 2013

Nanotori, or nanorings, are topological variants of nanotubes and are conceived to have different properties from their tubular form. In this study, the toroidal arrangement of boron nitride is introduced. Using classical molecular dynamics simulations, the thermal behaviour (thermal conductivity and thermal stability) of the boron nitride nanotorus and its relationship with the structural characteristics are investigated. Its circumferential thermal rectification strength displays a linear dependence on the bending coefficient of the nanostructure. Surface kinks are relatively inconsequential on its circumferential mode of conduction, as compared to its axial sense. The circumferential conductivity in the diffusive regime is calculated to be approximately 10 W/m K, while the axial conductivity is more than tenfold of this value. All nanotori with different toroidal characters show excellent thermal stability at extremely high temperatures approaching 3400 K. With consideration to its favourable properties, a thermal shield made up of a parallel row of nanotori is proposed as a nanoscale thermal insulation device.
Quantum photovoltaics in wire-dot-wire junctions
Authors: Berbezier Aude , Michelini Fabienne
Published: November 2013

We developed an effective tight-binding modeling for photovoltaic junctions made of a finite quantum dot chain connected to two semi-infinite quantum wires. We simulated I-V responses under resonant monochromatic illumination in the case of a two-dot junction by means of the Green's function technique. We thus showed a striking property in these dot-wire architectures: the photocurrent increases under bias.
The 25 mA continuous-wave surface-plasma source of H− ions
Authors: Belchenko Yu. , Gorbovsky A. , Sanin A. , Savkin V.
Published: November 2013

The ion source with the Penning geometry of electrodes producing continuous-wave beam of H− ions with current up to 25 mA was developed. Several improvements were introduced to increase source intensity, reliability, and lifetime. The collar around the emission aperture increases the electrons filtering. The apertures’ diameters of the ion-optical system electrodes were increased to generate the beam with higher intensity. An optimization of electrodes’ temperature was performed.
Precision phase control for the radio frequency system of K500 superconducting cyclotron at Variable Energy Cyclotron Centre, Kolkata
Authors: Som Sumit , Ghosh Surajit , Seth Sudeshna , Mandal Aditya , Paul Saikat , Roy Suprakash
Published: November 2013

Variable Energy Cyclotron Centre (VECC) has commissioned K500 Superconducting cyclotron (SCC) based on MSU and Texas A&M university cyclotrons. The radio frequency (RF) system of SCC has been commissioned with the stringent requirement of various RF parameters. The three-phase RF system of Superconducting cyclotron has been developed in the frequency range 9–27 MHz with amplitude and phase stability of 100 ppm and ±0.1°, respectively. The phase control system has the option to change the relative phase difference between any two RF cavities and maintain the phase stability within ±0.1° during round-the-clock cyclotron operation. The said precision phase loop consists of both analogue In-phase/Quadrature modulator to achieve faster response and also Direct Digital Synthesis based phase shifter to achieve wide dynamic range as well. This paper discusses detail insights into the various issues of phase control for the K500 SCC at VECC, Kolkata.
Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers
Authors: Appel Markus , Spehr Tinka Luise , Wipf Robert , Moers Christian , Frey Holger , Stühn Bernd
Published: November 2013

We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol−1) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.
A compact bipolar pulse-forming network-Marx generator based on pulse transformers
Authors: Zhang Huibo , Yang Jianhua , Lin Jiajin , Yang Xiao
Published: November 2013

A compact bipolar pulse-forming network (PFN)-Marx generator based on pulse transformers is presented in this paper. The high-voltage generator consisted of two sets of pulse transformers, 6 stages of PFNs with ceramic capacitors, a switch unit, and a matched load. The design is characterized by the bipolar pulse charging scheme and the compact structure of the PFN-Marx. The scheme of bipolar charging by pulse transformers increased the withstand voltage of the ceramic capacitors in the PFNs and decreased the number of the gas gap switches. The compact structure of the PFN-Marx was aimed at reducing the parasitic inductance in the generator. When the charging voltage on the PFNs was 35 kV, the matched resistive load of 48 Ω could deliver a high-voltage pulse with an amplitude of 100 kV. The full width at half maximum of the load pulse was 173 ns, and its rise time was less than 15 ns.
Phase space gradient of dissipated work and information: A role of relative Fisher information
Authors: Yamano Takuya
Published: November 2013

We show that an information theoretic distance measured by the relative Fisher information between canonical equilibrium phase densities corresponding to forward and backward processes is intimately related to the gradient of the dissipated work in phase space. We present a universal constraint on it via the logarithmic Sobolev inequality. Furthermore, we point out that a possible expression of the lower bound indicates a deep connection in terms of the relative entropy and the Fisher information of the canonical distributions.
Repulsive interactions of a lipid membrane with graphene in composite materials
Authors: Phan Anh D. , Hoang Trinh X. , Phan The-Long , Woods Lilia M.
Published: November 2013

The van der Waals interaction between a lipid membrane and a substrate covered by a graphene sheet is investigated using the Lifshitz theory. The reflection coefficients are obtained for a layered planar system submerged in water. The dielectric response properties of the involved materials are also specified and discussed. Our calculations show that a graphene covered substrate can repel the biological membrane in water. This is attributed to the significant changes in the response properties of the system due to the monolayer graphene. It is also found that the van der Waals interaction is mostly dominated by the presence of graphene, while the role of the particular substrate is secondary.
Violation of the mass-action law in dilute chemical systems
Authors: Brogioli Doriano
Published: November 2013

The mass-action law, which predicts the rates of chemical reactions, is widely used for modeling the kinetics of the chemical reactions and their stationary states, also for complex chemical reaction networks. However, violations of the mass-action equations have been reported in various cases: in confined systems with a small number of molecules, in non-ideally-stirred systems, when the reactions are limited by the diffusion, at high concentrations of reactants, or in chemical reaction networks with marginally stable mass-action equations. In this paper, I describe a new mechanism, leading to the violation of the mass-action equations, that takes place at a low concentration of at least one of the reactants; in this limit, the reaction rates can be easily inferred from the chemical reaction network. I propose that this mechanism underlies the replication stability of the hypercycles, a class of chemical reaction networks hypothetically connected with abiogenesis. I provide two simple examples of chemical reaction networks in which the mechanism leading to the violation of the mass-action law is present. I study the two chemical reaction networks by means of a simulation performed with a cellular automaton model. The results have a general validity and represent a limitation of the validity of the mass-action law, which has been overlooked up to now in the studies about the chemical reaction networks.
High-pressure Raman spectroscopy of phase change materials
Authors: Hsieh Wen-Pin , Zalden Peter , Wuttig Matthias , Lindenberg Aaron M. , Mao Wendy L.
Published: November 2013

We used high-pressure Raman spectroscopy to study the evolution of vibrational frequencies of the phase change materials (PCMs) Ge2Sb2Te5, GeSb2Te4, and SnSb2Te4. We found that the critical pressure for triggering amorphization in the PCMs decreases with increasing vacancy concentration, demonstrating that the presence of vacancies, rather than differences in the atomic covalent radii, is crucial for pressure-induced amorphization in PCMs. Compared to the as-deposited amorphous phase, the pressure-induced amorphous phase has a similar vibrational spectrum but requires much lower laser power to transform into the crystalline phase, suggesting different kinetics of crystallization, which may have implications for applications of PCMs in non-volatile data storage.
Surface excitons on a ZnO (000-1) thin film
Authors: Kuehn S. , Friede S. , Sadofev S. , Blumstengel S. , Henneberger F. , Elsaesser T.
Published: November 2013

Elementary excitations at the polar (000-1) surface of a 20 nm pseudomorphically grown ZnO thin film are examined by steady state and time-resolved photoluminescence spectroscopy at low temperature. We control the density of emission centers through the deposition of prototypical organic molecules with a carboxylic acid anchor group by the Langmuir-Blodgett technique. Knowledge of the precise film thickness, defect concentrations and number density of deposited molecules leads us to associate the surface exciton emission to defect-related localization centers that are generated through a photochemical process.
The bonding, charge distribution, spin ordering, optical, and elastic properties of four MAX phases Cr2AX (A = Al or Ge, X = C or N): From density functional theory study
Authors: Li Neng , Mo Yuxiang , Ching Wai-Yim
Published: November 2013

In this work, we assess a full spectrum of properties (chemical bonding, charge distribution, spin ordering, optical, and elastic properties) of Cr2AC (A = Al, Ge) and their hypothetical nitride counterparts Cr2AN (A = Al, Ge) based on density functional theory calculations. The calculated total energy values indicate that a variety of spin ordering of these four compounds depending on interlayer-interactions between M-A and M-X within the sublattice, which is supported by bonding analysis. MAX phase materials are discovered to possess exotic magnetic properties which indicates that these materials could serve as promising candidates for novel layered magnetic materials for various electronic and spintronic applications. Further analysis of optical properties for two polarization vectors of Cr2AX shows that the reflectivity is high in the visible-ultraviolet region up to ∼15 eV suggesting Cr2AX as a promising candidate for use as a coating material. The elastic coefficients (Cij) and bulk mechanical properties [bulk modulus (K), shear modulus (G), Young's modulus (E), Poisson's ratio (η), and Pugh ratio (G/K)] of these four Cr2AX compounds are also calculated and analyzed, which pave the way to predict or design new MAX phases that are less brittle or tougher by having a lower G/K value or higher η.

At the request of the authors and editor, this article is being retracted effective 14 March 2014.
Six-dimensional quantum dynamics study for the dissociative adsorption of HCl on Au(111) surface
Authors: Liu Tianhui , Fu Bina , Zhang Dong H.
Published: November 2013

The six-dimensional quantum dynamics calculations for the dissociative chemisorption of HCl on Au(111) are carried out using the time-dependent wave-packet approach, based on an accurate PES which was recently developed by neural network fitting to density functional theory energy points. The influence of vibrational excitation and rotational orientation of HCl on the reactivity is investigated by calculating the exact six-dimensional dissociation probabilities, as well as the four-dimensional fixed-site dissociation probabilities. The vibrational excitation of HCl enhances the reactivity and the helicopter orientation yields higher dissociation probability than the cartwheel orientation. A new interesting site-averaged effect is found for the title molecule-surface system that one can essentially reproduce the six-dimensional dissociation probability by averaging the four-dimensional dissociation probabilities over 25 fixed sites.
Note: Production of a mercury beam with an electron cyclotron resonance ion source
Authors: Vondrasek R. , Pardo R. , Scott R.
Published: November 2013

An electron cyclotron resonance ion source has been utilized to produce mercury beams with intensities of 4.5 eμA of 202Hg29+ and 3.0 eμA of 202Hg31+ from natural abundance mercury metal. The production technique relies on the evaporation of liquid mercury into the source plasma vacuum region and utilizes elemental mercury instead of a volatile organic compound as the neutral feed material.
Structure disorder degree of polysilicon thin films grown by different processing: Constant C from Raman spectroscopy
Authors: Wang Quan , Zhang Yanmin , Hu Ran , Ge Daohan , Ren Naifei
Published: November 2013

Flat, low-stress, boron-doped polysilicon thin films were prepared on single crystalline silicon substrates by low pressure chemical vapor deposition. It was found that the polysilicon films with different deposition processing have different microstructure properties. The confinement effect, tensile stresses, defects, and the Fano effect all have a great influence on the line shape of Raman scattering peak. But the effect results are different. The microstructure and the surface layer are two important mechanisms dominating the internal stress in three types of polysilicon thin films. For low-stress polysilicon thin film, the tensile stresses are mainly due to the change of microstructure after thermal annealing. But the tensile stresses in flat polysilicon thin film are induced by the silicon carbide layer at surface. After the thin film doped with boron atoms, the phenomenon of the tensile stresses increasing can be explained by the change of microstructure and the increase in the content of silicon carbide. We also investigated the disorder degree states for three polysilicon thin films by analyzing a constant C. It was found that the disorder degree of low-stress polysilicon thin film larger than that of flat and boron-doped polysilicon thin films due to the phase transformation after annealing. After the flat polysilicon thin film doped with boron atoms, there is no obvious change in the disorder degree and the disorder degree in some regions even decreases.
Heterojunction band offsets and dipole formation at BaTiO3/SrTiO3 interfaces
Authors: Balaz Snjezana , Zeng Zhaoquan , Brillson Leonard J.
Published: November 2013

We used a complement of photoemission and cathodoluminescence techniques to measure formation of the BaTiO3 (BTO) on SrTiO3 (STO) heterojunction band offset grown monolayer by monolayer by molecular beam epitaxy. X-ray photoemission spectroscopy (XPS) provided core level and valence band edge energies to monitor the valence band offset in-situ as the first few crystalline BTO monolayers formed on the STO substrate. Ultraviolet photoemission spectroscopy (UPS) measured Fermi level positions within the band gap, work functions, and ionization potentials of the growing BTO film. Depth-resolved cathodoluminescence spectroscopy measured energies and densities of interface states at the buried heterojunction. Kraut-based XPS heterojunction band offsets provided evidence for STO/BTO heterojunction linearity, i.e., commutativity and transitivity. In contrast, UPS and XPS revealed a large dipole associated either with local charge transfer or strain-induced polarization within the BTO epilayer.
True green semipolar InGaN-based laser diodes beyond critical thickness limits using limited area epitaxy
Authors: Hardy Matthew T. , Wu Feng , Shan Hsu Po , Haeger Daniel A. , Nakamura Shuji , Speck James S. , DenBaars Steven P.
Published: November 2013

Semipolar oriented laser diodes (LDs) have fundamental advantages over c-plane oriented LDs, however, the thickness and composition of InGaN waveguiding layers and AlGaN cladding are limited by the onset of stress relaxation via threading dislocation glide on the c-plane slip system. Limited area epitaxy minimizes misfit dislocation (MD) formation by preventing pre-existing TDs from entering a patterned mesa. We examine the effects of mesa height and facet evolution for LAE grown strained layers. Significant MD formation was suppressed by at least a factor of four for Al0.1Ga0.9N/GaN superlattices, enabling AlGaN-clad structures similar to those used in c-plane LDs. We then demonstrate AlGaN-clad blue (456 nm) LDs with threshold current density (Jth) of 4.5 kA/cm2 and GaN-clad true green (523 nm) LDs with Jth of 12 kA/cm2. TEM measurements of the green LD confirm reduction of MD densities with reduction of MD run length. LAE is effective for improving the optical confinement factor of semipolar LDs and offers a glimpse of the design space that may soon be available using low TD density bulk GaN substrates.
Identification of several propagation regimes for terahertz surface waves guided by planar Goubau lines
Authors: Gacemi D. , Degiron A. , Baillergeau M. , Mangeney J.
Published: November 2013

We report on the experimental and numerical characterization of planar Goubau lines in the terahertz frequency range. We demonstrate the existence of three propagation regimes that depend on the ratio between the thickness of the dielectric slab and the operation wavelength. Although two of these regimes are dispersive, it is possible to mitigate this undesirable property by a judicious choice of the materials used to fabricate the structures. As an example, we show that Au planar Goubau lines supported by thin layers of Kapton have very interesting characteristics including a modest dispersion coefficient (0.28 ps/mm) and low losses (<0.4 mm−1) up to 0.8 THz.
Note: Transient negative ions as initiators of oxygen fixation in <20 eV electron-irradiated DNA
Authors: Massey Sylvain , Bass Andrew D. , Sanche Léon
Published: November 2013

This note represents a significant addition to our previous manuscript [N. Mirsaleh-Kohan, A. D. Bass, P. Cloutier, S. Massey, and L. Sanche, J. Chem. Phys. 136, 235104 (2012)] where we demonstrated that enhancements in the electron stimulated desorption yields of O− and OH− from O2 exposed DNA samples were due to the reactions of O2 with electron-induced damage sites within the DNA. Here, we investigate the attachment of O2 to electron-irradiated DNA as a function of electron energy and find a local maximum for O2 attachment to DNA at ∼11.4 eV. This reaction is likely initiated by the production of transient negative ions that dissociate to form RCHx−1• radicals. This work is thus relevant to our understanding of how O2 modulates radiation induced damage in cellular DNA and upon the question of the radio-sensitization of cells during, for example, radiotherapy.
Increasing the creation yield of shallow single defects in diamond by surface plasma treatment
Authors: Osterkamp Christian , Scharpf Jochen , Pezzagna Sebastien , Meijer Jan , Diemant Thomas , Jürgen Behm Rolf , Naydenov Boris , Jelezko Fedor
Published: November 2013

Single Nitrogen-Vacancy (NV) centers in diamond close to the crystal surface are very promising magnetic field sensors with very high sensitivity. Here, we report the enhanced creation of very shallow (less than 3 nm below the diamond surface) NV centers by using fluorine and oxygen plasma treatment. We observe a four fold increase—from 0.11% to about 0.45% in the production yield when the sample surface is terminated with fluorine or oxygen atoms. This effect is explained by the stabilization of the NV's negative charge state which is influenced by the various defects present on the diamond surface.