bluuebunny/crossref_metadata_2025 huggingface dataset:
De la notion degrammaire standarddans une optique diglossique du français
Authors: ZRIBI-HERTZ ANNE
Published: January 2013

Cet article cherche à préciser le schéma diglossique de description du français envisagé dans Zribi-Hertz (2011a), qui propose de représenter la compétence linguistique d'un francophone par deux grammaires internes en intersection, respectivement étiquetéesGrammaire StandardetGrammaire Dialectale. Quel est le statut de laGrammaire Standarddans ce schéma ? S'agit-il bien d'une grammaire interne, au sens où l'entend la grammaire générative ? Ou seulement d'une grammaire externe incarnant une norme imposée aux locuteurs par des grammairiens ? L'hypothèse ici défendue est que les deux grammaires sécantes du schéma diglossique doivent bien être des grammaires internes, mais que la Grammaire Standard interne, régie en tant que telle par le Principe de Cohérence présidant à toute grammaire interne, est à distinguer de la Norme Académique fixée de façon institutionnelle sur la base d'écrits attestés produits par des auteurs divers, et qui échappe de ce fait au Principe de Cohérence. L'argumentation de cet article s'appuie sur une étude de cas: les syntagmes nominaux sans nom lexical (DPSN) en français hexagonal moderne, dont les propriétés attestées ne sont pas prédites par la grammaire énoncée par la Norme Académique. Il est soutenu, sur la base de productions attestées récentes recueillies sur internet, que la grammaire académique souffre d'incohérences qui la rendent inapprenable (non intériorisable), et que les francophones ont donc mis en place une grammaire interne cohérente qu'ils intègrent aussi bien à leur Grammaire Dialectale qu'à leur Grammaire Standard.
Perspectives diglossique et variationnelle – Complémentarité ou incompatibilité? Quelques éclairages sociolinguistiques
Authors: BILLIEZ JACQUELINE , BUSON LAURENCE
Published: January 2013

L'hypothèse d'une diglossie française est-elle une voie opérante pour analyser et développer les compétences linguistiques de locuteurs, enfants ou adultes, francophones? Cet article se propose d'apporter des éclairages sociolinguistiques sur cette question aujourd'hui largement discutée, en linguistique comme en didactique du français.

Notre contribution articule plusieurs arguments pouvant appuyer, nuancer, voire contredire le bien-fondé de cette approche, dans une perspective à la fois sociolinguistique, psycholinguistique, et didactique.

En confrontant la perspective diglossique à la réalité des pratiques stylistiques d'enfants et d'adultes sur la base d'un corpus de données recueillies en situations formelles et informelles, nous montrons combien il est délicat d'aborder la variation en termes dichotomiques si l'on envisage l'ensemble des niveaux linguistiques engagés dans la communication et pas seulement quelques variables isolées caractéristiques de deux extrêmes du continuum stylistique.
Agricultural development and the industry life cycle on the Brazilian frontier
Authors: Hall Simon C. , Caviglia-Harris Jill
Published: January 2013

The occupation of the last remaining tropical forests has been an initiative of many developing nations that is debated by the global community due to impacts on soil erosion, biodiversity loss and contributions to global climate change. Arguments against development range from the irreversible nature of tropical deforestation to the synergistic losses associated with environmental degradation and continued poverty. The focus of this paper is to determine if evidence of market advancements and growth can be found in an Amazonian settlement, thus providing counter-evidence for the boom–bust pattern of development that has been predicted for much of the Amazon. Using panel survey data (for four survey waves between 1996 and 2009), we find trends that are consistent with the industrial life cycle, suggesting a pattern that is more consistent with growth, development and consolidation.
First clues to the existence of two input languages: Pragmatic and lexical differentiation in a bilingual child
Authors: NICOLADIS ELENA
Published: January 2013

While it is now commonly accepted that simultaneous bilingual children can differentiate their two languages from very early in development, it is still not very well understood how they come to understand that there are two languages in their input. The purpose of this study was to examine how a bilingual child might come to an understanding of the existence of two languages in terms of pragmatic differentiation (use of the appropriate language for the context) and lexical differentiation (use of translation equivalents). Using data from a Portuguese-English bilingual child from 1;0 to 1;6, this study showed that the child showed evidence of pragmatic differentiation before lexical differentiation. If these results are replicated, they suggest that bilingual children's understanding of the appropriate social use of their two languages may lead to an understanding that the translation equivalents in their vocabulary belong to two distinct input languages.
EPIDEMIC DYNAMICS ON RANDOM AND SCALE-FREE NETWORKS
Authors: BARTLETT J. , PLANK M. J.
Published: January 2013

Random networks were first used to model epidemic dynamics in the 1950s, but in the last decade it has been realized that scale-free networks more accurately represent the network structure of many real-world situations. Here we give an analytical and a Monte Carlo method for approximating the basic reproduction number${R}_{0} $of an infectious agent on a network. We investigate how final epidemic size depends on${R}_{0} $and on network density in random networks and in scale-free networks with a Pareto exponent of 3. Our results show that: (i) an epidemic on a random network has the same average final size as an epidemic in a well-mixed population with the same value of${R}_{0} $; (ii) an epidemic on a scale-free network has a larger average final size than in an equivalent well-mixed population if${R}_{0} \lt 1$, and a smaller average final size than in a well-mixed population if${R}_{0} \gt 1$; (iii) an epidemic on a scale-free network spreads more rapidly than an epidemic on a random network or in a well-mixed population.
Multi-modality: a new approach for the treatment of major depressive disorder
Authors: Richelson Elliott
Published: January 2013

Effective treatment with antidepressants is currently limited by factors that affect treatment compliance, including delay in onset of therapeutic effects and intolerable side-effects. Recent data suggest that use of antidepressant combinations with different mechanisms of action may be a better first-line strategy prior to augmentation with other drug classes. The rationale for this approach is that combining multiple pharmacological actions affecting multiple monoamine targets produces greater efficacy. Several new multi-modal compounds are in development and early results for the most advanced agents indicate shorter onset of therapeutic effects and improved tolerability. By modulating multiple receptors and transmitter systems, it is hoped that these new agents may also treat some of the associated symptoms of major depressive disorder, such as anxiety and cognitive dysfunction.
Anti-anhedonic activity of long-term lithium treatment in rats exposed to repeated unavoidable stress
Authors: Marchese Giovanna , Scheggi Simona , Secci Maria Elena , De Montis Maria Graziella , Gambarana Carla
Published: January 2013

Behavioural and neurochemical responses to palatable food exposure represent an index of hedonic competence. In rats, a palatable meal increases extra-neuronal dopamine levels in the nucleus accumbens shell (NAcS) that confers to it incentive salience and reinforcing value. Repeated stress exposure decreases dopamine output and impairs the NAcS dopaminergic response to palatable food and the competence to acquire a vanilla sugar (VS)-reinforced instrumental behaviour [VS-sustained appetitive behaviour (VAB)]. Moreover, chronic stress exposure disrupts reactivity to aversive stimuli. A 3-wk treatment with lithium, the gold-standard treatment in bipolar disorder, tonically reduces NAcS dopamine output and the reactivity to aversive stimuli. However, it does not affect the dopaminergic response to VS and the competence to acquire VAB. This study investigated whether repeated lithium administration is endowed with anti-anhedonic activity. The NAcS dopaminergic response to VS and the competence to acquire VAB and sucrose self-administration (SA), in terms of fixed-ratio (FR)1, FR5 and progressive ratio schedules of reinforcement, were studied in saline or lithium-treated groups of non-food-deprived rats exposed or not to repeated unavoidable stress. Chronic stress exposure impaired the NAcS dopaminergic response to VS, acquisition of VAB and sucrose SA, in terms of FR1 and FR5 schedules of reinforcement and breaking point score. Repeated lithium treatment restored these parameters to control group values, even when treatment began in rats already showing an anhedonia-like condition. Since the breaking point defines the reinforcement efficacy of a hedonic stimulus, the present data suggest that lithium treatment is endowed with anti-anhedonic activity in rats.
Dome Fuji Seeing -the Summer Results and the Future Winter-over Observations
Authors: Okita Hirofumi , Takato Naruhisa , Ichikawa Takashi , Bonner Colin S. , Ashley Michel C. B. , Storey John W. V. ,   the 51st and 52nd JARE Dome Fuji teams
Published: January 2013

We carried out the first seeing measurements at Dome Fuji in the 2010–2011 austral summer. From these observations, we found that the summer seeing at Dome Fuji was 1.2″ (mean), 1.1″ (median), 0.83″ (25th percentile) and 1.5″ (75th percentile), respectively. We also found that the seeing changed continuously and had a minimum around 0.7″ at ~18:00 hours daily. We compared the seeing with some weather parameters obtained from the 16 m mast, and found that the seeing had good correlations with atmosphere temperature and wind shear. These results suggest that the seeing is degraded by turbulence near the surface boundary layer. Because the data were obtained only over a short duration in summer, the general characteristics of Dome Fuji's seeing could not be evaluated. We plan to observe the seeing in winter with a stand-alone DIMM telescope. This new DIMM, which we named the Dome Fuji Differential Image Motion Monitor (DF–DIMM), will be installed at Dome Fuji in January 2013.
A CMB B-mode Search with Three Years of BICEP Observations
Authors: Bischoff Colin ,   for the BICEP Collaboration
Published: January 2013

The search for B-mode, or curl-type, polarization in the Cosmic Microwave Background is the most promising technique to constrain or detect primordial gravitational waves predicted by the theory of inflation. The Bicep telescope, which observed from the South Pole for three years from 2006 through 2008, is the first experiment specifically designed to target this signal. We review the observational motivations for inflation, the advantages of B-mode observations as a technique for detecting the gravitational wave background, and the design features of Bicep that optimize it for this search. The final analysis of all three seasons of Bicep data is in progress, representing a 50% increase in integration time compared to the result from Chiang et al. (2010). A preview of the three year result includes E-mode and B-mode maps, as well as the projected constraint on r, the tensor-to-scalar ratio.
CMB Polarization with BICEP2 and Keck-Array
Authors: Pryke Clement ,   for the BICEP2 and Keck-Array Collaborations
Published: January 2013

BICEP2 is an evolution from the highly successful BICEP CMB polarization experiment. In turn Keck-Array is an array of BICEP2 like receivers to achieve an additional increase in sensitivity. All these experiments are located at the South Pole in Antarctica and target the CMB B-mode polarization signal which is predicted to exist in many simpler models of Inflation at angular scales of several degrees. The design and performance of BICEP2 and Keck-Array is described and some preliminary polarization maps are presented.
The South Pole Telescope: Latest Results and Future Prospects
Authors: Benson Bradford ,   the SPT Collaboration (pole.uchicago.edu)
Published: January 2013

The South Pole Telescope is a 10 meter telescope optimized for sensitive, high-resolution measurements of the cosmic microwave background (CMB) anisotropy and millimeter-wavelength sky. In November 2011, the SPT completed the 2500 deg2 SPT-SZ survey. The survey has led to several major cosmological results, derived from measurements of the fine angular scale primary and secondary CMB anisotropies, the discovery of galaxy clusters via the Sunyaev-Zel'dovich (SZ) effect and the resulting mass-limited cluster catalog, and the discovery of a population of distant, dusty star forming galaxies (DSFGs). In January 2012, the SPT was equipped with a new polarization sensitive camera, SPTpol, which will enable detection of the contribution to the CMB polarization power spectrum from lensing by large scale structure (the so-called “lensing B-modes”) and, on larger angular scales, a detection or improved upper limit on the primordial inflationary signal (“gravitational-wave B-modes”), thereby constraining the energy scale of Inflation. Development is underway for SPT-3G, the third-generation camera for SPT. The SPT-3G survey will cross the threshold from statistical detection of B-mode CMB lensing to imaging the fluctuations at high signal-to-noise; enabling the separation of lensing and inflationary B-modes and improving the constraint on the sum of the neutrino masses Σmν to a level relevant for exploring the neutrino mass hierarchy.
Toward a 10,000-element B-Mode Experiment
Authors: Kuo Chao-Lin ,   for the BICEP3 and POLAR1 Collaborations
Published: January 2013

In this paper, we introduce two compact, large-throughput CMB polarimeter designs (POLAR1 and BICEP3). These pathfinder experiments will pave the way for a comprehensive multi-frequency South Pole B-mode survey that, when jointly analyzed with arcminute-scale polarization data, can conclusively answer the question whether there is an appreciable fraction (>1%) of the primordial perturbations in the form of tensor modes (gravitational waves).
The IceCube Neutrino Telescope
Authors: Gaisser Thomas K. ,   for the IceCube Collaboration
Published: January 2013

Construction of IceCube at the Amundsen-Scott South Pole Station was completed at the end of 2010 after eight construction seasons. The detector consists of 5,160 digital optical modules on 86 cables with 60 modules each, viewing in total a cubic kilometer of ice between 1,450 and 2,450 meters below the surface. IceCube includes a sub-array called DeepCore consisting of 8 special cables, and providing a more densely instrumented region with a lower energy threshold in the deep center of the array. IceCube also includes an air shower array called IceTop directly above the deep detector. Optical modules in all three components of the detector are fully integrated into a single data acquisition system. Data taking and analysis began during construction and continues with the completed detector. This paper describes recent results from IceCube.
The Exploration of the ISM from Antarctica
Authors: Wolfire Mark G.
Published: January 2013

Antarctica presents a unique environment for the exploration of the interstellar medium. The low column of water vapor opens windows for sub-mm and THz astronomy from ground and sub-orbital observatories while the stable atmosphere holds promise for THz interferometry. Various current and potentially future facilities occupy a niche not available to current space or stratospheric instruments. These allow line and continuum observations addressing key questions in e.g., star formation, galactic evolution, and the life-cycle of interstellar clouds. This review presents scientific questions that can be addressed by the suite of current and future Antarctic observatories.
Winterover scientists in Antarctic Astrophysics
Authors: Tothill N. F. H. , Martin C. L.
Published: January 2013

Astronomy in Antarctica is largely carried out in winter, and so winterover scientists are required to run the instruments. A winterover appointment is a unique opportunity for a scientist, but brings challenges for both the scientist and the larger instrument team. We give a brief review of how winterovers work and their experiences. Although recent projects have required less support from winterover scientists, we believe that they will be a feature of Antarctic astronomy and astrophysics into the future.
Astronomy from 80 Degrees North on Ellesmere Island, Canada
Authors: Steinbring Eric
Published: January 2013

Site testing carried out on Ellesmere Island over recent years has shown that mountainous coastal terrain there can provide high clear-sky fractions in the long dark season, with low precipitable water-vapour column and prospects for excellent seeing. This presents new possibilities for time-domain and survey-mode science in the northern hemisphere, allowing uninterrupted high-precision photometry in the optical/near-infrared, but also gains in the submillimetre/millimetre. Efforts underway at the Eureka research station, at 80 degrees latitude, are reviewed. This location provides year-round access to a nearby site being developed as a pathfinder observatory. A program of variable-star and transient searches involving a wide-field imaging system has begun, with some early results. Plans include extrasolar-planet hunting via transit surveys, and future directions are discussed.
Precision CMB measurements with long-duration stratospheric balloons: activities in the Arctic
Authors: de Bernardis P. , Masi S. ,   for the OLIMPO and LSPE teams
Published: January 2013

We report on the activities preparing long duration stratospheric flights, suitable for CMB (Cosmic Microwave Background) measurements, in the Arctic region. We focus on pathfinder flights, and on two forthcoming experiments to be flown from Longyearbyen (Svalbard islands): the OLIMPO Sunyaev-Zeldovich spectrometer, and the Large-Scale Polarization Explorer (LSPE).
Present and Future Observations of the Earthshine from Antarctica
Authors: Briot Danielle , Arnold Luc , Jacquemoud Stéphane
Published: January 2013

It is likely that images of Earth-like planets will be obtained in the next years. The first images will actually come down to single dots, in which biomarkers can be searched. Taking the Earth as a example of planet providing life, Earthshine observations showed that the spectral signature of photosynthetic pigments and atmospheric biogenic molecules was detectable, suggesting that, in principle, life on other planets could be detected on a global scale, if it is widely spread and distinguishable from known abiotic spectral signatures. As for the Earth, we already showed that the Vegetation Red Edge which is related to chlorophyll absorption features was larger when continents, versus oceans, were facing the Moon. It proved that an elementary mapping of a planet was even possible. In the frame of the LUCAS (LUmière Cendrée en Antarctique par Spectroscopie) project, the Earthshine has been measured in the Concordia Research Station (Dome C, Antarctica) long enough to observe variations corresponding to different parts of the Earth facing the Moon. An extension of this project, called LUCAS II, would allow long-term observations to detect seasonal variations in the vegetation signal. These data, together with precise measurements of the Earth's albedo, will help to validate a model of global and spectral albedo of our planet.
Progress and Results from the Chinese Small Telescope ARray (CSTAR)
Authors: Zhou Xu , Ashley M. C. B. , Cui Xiangqun , Feng Longlong , Gong Xuefei , Hu Jingyao , Jiang Zhaoji , Kulesa C. A. , Lawrence J. S. , Liu Genrong , Luong-Van D. M. , Ma Jun , Macri Lucas M. , Meng Zeyang , Moore A. M. , Qin Weijia , Shang Zhaohui , Storey J. W. V. , Sun Bo , Travouillon T. , Walker C. K. , Wang Jiali , Wang Lifan , Wang Lingzhi , Wang Songhu , Wu Jianghua , Wu Zhenyu , Xia Lirong , Yan Jun , Yang Ji , Yang Huigen , Yao Yongqiang , Yuan Xiangyan , York D. , Zhang Hui , Zhang Zhanhai , Zhou Jilin , Zhu Zhenxi , Zou Hu
Published: January 2013

In 2008 January the 24th Chinese expedition team successfully deployed the Chinese Small Telescope ARray (CSTAR) to Dome A, the highest point on the Antarctic plateau. CSTAR consists of four 14.5cm optical telescopes, each with a different filter (g, r, i and open) and has a 4.5°×4.5° field of view (FOV). Based on the CSTAR data, initial statistics of astronomical observational site quality and light curves of variable objects were obtained. To reach higher photometric quality, we are continuing to work to overcome the effects of uneven cirrus cloud cirrus, optical “ghosts” and intra-pixel sensitivity. The snow surface stability is also tested for further astronomical observational instrument and for glaciology studies.
Next Generation Deep 2μm Survey
Authors: Mould Jeremy
Published: January 2013

There is a major opportunity for the KDUST 2.5 m telescope to carry out the next generation IR survey. A resolution of 0.2 arcsec is obtainable from Dome A over a wide field. This opens a unique discovery space during the 2015–2025 decade.

A next generation 2μm survey will feed JWST with serendipitous targets for spectroscopy, including spectra and images of the first galaxies.
The SCAR Astronomy & Astrophysics from Antarctica Scientific Research Programme
Authors: Storey John W. V. , Abe Lyu , Andersen Michael , Anderson Philip , Burton Michael , Cui Xiangqun , Ichikawa Takashi , Karle Albrecht , Lloyd James , Masi Silvia , Steinbring Eric , Travouillon Tony , Tuthill Peter , Zhou HongYang
Published: January 2013

SCAR, the Scientific Committee on Antarctic Research, is, like the IAU, a committee of ICSU, the International Council for Science. For over 30 years, SCAR has provided scientific advice to the Antarctic Treaty System and made numerous recommendations on a variety of matters. In 2010, Astronomy and Astrophysics from Antarctica was recognized as one of SCAR's five Scientific Research Programs. Broadly stated, the objectives of Astronomy & Astrophysics from Antarctica are to coordinate astronomical activities in Antarctica in a way that ensures the best possible outcomes from international investment in Antarctic astronomy, and maximizes the opportunities for productive interaction with other disciplines. There are four Working Groups, dealing with site testing, Arctic astronomy, science goals, and major new facilities. Membership of the Working Groups is open to any professional working in astronomy or a related field.
Dome C site testing: long term statistics of integrated optical turbulence parameters at ground level
Authors: Aristidi E. , Agabi A. , Fossat E. , Ziad A. , Abe L. , Bondoux E. , Bouchez G. , Challita Z. , Jeanneaux F. , Mékarnia D. , Petermann D. , Pouzenc C.
Published: January 2013

We present long term site testing statistics based on DIMM and GSM data obtained at Dome C, Antarctica. These data have been collected on the bright star Canopus since the end of 2003. We give values of the integrated turbulence parameters in the visible (wavelength 500 nm). The median value we obtained for the seeing are 1.2 arcsec, 2.0 arcsec and 0.8 arcsec at respective elevations of 8m, 3m and 20m above the ground. The isoplanatic angle median value is 4.0 arcsec and the median outer scale is 7.5m. We found that both the seeing and the isoplanatic angle exhibit a strong dependence with the season (the seeing is larger in winter while the isoplanatic angle is smaller).
Design and field testing of the Fish-Eye lens for optical atmospheric observations
Authors: Syniavskyi Ivan , Ivanov Yuriy , Chernous Sergey , Sigernes Fred
Published: January 2013

The Fish-Eye lens MAO-08 is intended for observations of weak extended objects (aurora, twilight and dawn phenomena, stratospheric clouds, etc.) in narrow spectral bands with variable passband filters VARISPEC and in white light. It is valuable for astronomical observation for the target – background problem when we need to estimate the spectral transparence of the atmosphere. Besides having high power this lens can be used for meteor observations. It has been tested during the winter field conditions.
SCIDAR: an optical turbulence profiler for Dome A
Authors: Liu Li-Yong , Yao Yong-Qiang , Vernin Jean , Chadid Merieme , Wang Hong-Shuai , Wang Yi-Ping
Published: January 2013

This paper introduces a plan to detect turbulence profiles at Dome A with a Single Star Scidar (SSS), to enhance our understanding of the characteristics of the site. The development of a portable monitor for profiling vertical atmospheric optical turbulence and wind speed is presented. By analyzing the spatial auto and cross-correlation functions of very short exposure images of single star scintillation patterns, the SSS can provide the vertical profiles of turbulence intensity C2n(h) and wind speed V(h). A SSS prototype is already operational at Ali in Tibet which will be improved in order to become fully robotic and adapted to extreme weather conditions that prevail at Dome A in Antarctica.
SONG China project – participating in the global network
Authors: Deng Licai , Xin Yu , Zhang Xiaobin , Li Yan , Jiang Xiaojun , Wang Guomin , Wang Kun , Zhou Jilin , Yan Zhengzhou , Luo Zhiquan
Published: January 2013

SONG (Stellar Observations Network Goup) is a low-cost ground based international collaboration aimed at two cutting edge problems in contemporary astrophysics in the time-domain: 1) Direct diagnostics of the internal structure of stars and 2) looking for and studying extra solar planets, possibly in the habitable zone. The general plan is to set up a network of 1m telescopes uniformly distributed in geographic latitude (in both hemispheres). China jointed the collaboration (initiated by Danish astronomers) at the very beginning. In addition to SONG's original plan (http://song.phys.au.dk), the Chinese team proposed a parallel photometry subnet work in the northern hemisphere, namely 50BiN (50cm Binocular Network, previously known as mini-SONG), to enable a large field photometric capability for the network, therefore maximising the potential of the network platform. The network will be able to produce nearly continuous time series observations of a number of selected objects with high resolution spectroscopy (SONG) and accurate photometry (50BiN), and to produce ultra-high accuracy photometry in dense field to look for micro-lensing events caused by planetary systems. This project has great synergy with Chinese Astronomical activities in Antarctica (Dome A), and other similar networks (e.g. LCOGT). The plan and current status of the project are overviewed in this poster.
Electron-antineutrino disappearance seen by Daya Bay reactor neutrino experiment
Authors: Wang Ruiguang
Published: January 2013

The Daya Bay Reactor Neutrino Experiment has measured a non-zero value for the neutrino mixing angle θ13 with a significance of 7.7 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near and one far underground experimental halls. With a 116.8 kton-GWth-day live-time exposure in 139 days, 28,909 (205,308) electron-antineutrino candidates were detected at the far hall (near hall). The ratio of the observed to expected number of antineutrinos at the far hall is R = 0.944 ± 0.007 ± 0.003 (syst). A rate-only analysis finds sin22θ13 = 0.089 ± 0.010 (stat) ± 0.005 (syst) in a three-neutrino framework.
Test and Commissioning of the AST3-1 Control System
Authors: Li Xiaoyan , Wang Daxing
Published: January 2013

The first of three Antarctic Survey Telescopes (AST3-1), a 50/68cm Schmidt-like equatorial-mount telescope, is the first trackable Chinese telescope operating on the Antarctic plateau. It was installed at Dome A (80°22′, 77°21′E, 4,093m), the highest place on the Antarctic plateau, in 2012. The telescope is unmanned during night-time operations through the Austral winter. The telescope optics and mechanics, as well as the motors and position sensors, are exposed to a harsh environment. The mechanics is enclosed with a foldable tent-like dome to prevent snow, diamond dust and ice. While the control cabinet containing drive boxes, circuit board boxes, power converters and the Telescope Control Computer (TCC) is located inside the warm instrumental module. In about 15 weeks remote testing and commissioning, from January 24 when the expedition team left there to May 8, when the communication failed, we obtained images with the best FWHM of less than 2″. We also recorded the telescope movement performance and fine-tuned the dynamic properties of the telescope control system. Some experiences and lessons will be disscussed in this paper.
Classification of Quasars and Stars by Supervised and Unsupervised Methods
Authors: Zhang Yanxia , Zhao Yongheng , Zheng Hongwen , Wu Xue-bing
Published: January 2013

Targeting quasar candidates is always an important task for large spectroscopic sky survey projects. Astronomers never give up thinking out effective approaches to separate quasars from stars. The previous methods on this issue almost belong to supervised methods or color-color cut. In this work, we compare the performance of a supervised method – Support Vector Machine (SVM)– with that of an unsupervised method one-class SVM. The performance of SVM is better than that of one-class SVM. But one-class SVM is an unsupervised algorithm which is helpful to recognize rare or mysterious objects. Combining supervised methods with unsupervised methods is effective to improve the performance of a single classifier.
Multivariate Spatial Covariance Analysis of 99MTc-Exametazime SPECT Images in Dementia with Lewy Bodies and Alzheimer'S Disease: Utility in Differential Diagnosis
Authors: Colloby Sean J , Taylor John-Paul , Davison Christopher M , Lloyd Jim J , Firbank Michael J , McKeith Ian G , O'Brien John T
Published: January 2013

We examined 99mTc-exametazime brain blood flow single-photon emission computed tomography (SPECT) images using a spatial covariance analysis (SCA) approach to assess its diagnostic value in distinguishing dementia with Lewy bodies (DLB) from Alzheimer's disease (AD). Voxel SCA was simultaneously applied to a set of preprocessed images (AD, n = 40; DLB, n = 26), generating a series of eigenimages representing common intercorrelated voxels in AD and DLB. Linear regression derived a spatial covariance pattern (SCP) that discriminated DLB from AD. To investigate the diagnostic value of the model SCP, the SCP was validated by applying it to a second, independent, AD and DLB cohort (AD, n = 34; DLB, n = 29). Mean SCP expressions differed between AD and DLB ( F1,64 = 36.2, P < 0.001) with good diagnostic accuracy (receiver operating characteristic (ROC) curve area 0.87, sensitivity 81%, specificity 88%). Forward application of the model SCP to the independent cohort revealed similar differences between groups (F1,61 = 38.4, P < 0.001), also with good diagnostic accuracy (ROC 0.86, sensitivity 80%, specificity 80%). Multivariate analysis of blood flow SPECT data appears to be robust and shows good diagnostic accuracy in two independent cohorts for distinguishing DLB from AD.
Superiority of Preventive Antibiotic Treatment Compared with Standard Treatment of Poststroke Pneumonia in Experimental Stroke: A Bed to Bench Approach
Authors: Hetze Susann , Engel Odilo , Römer Christine , Mueller Susanne , Dirnagl Ulrich , Meisel Christian , Meisel Andreas
Published: January 2013

Stroke patients are prone to life-threatening bacterial pneumonia. Previous experimental stroke studies have demonstrated that preventive antibiotic treatment (PAT) improves outcome compared with placebo treatment, which however does not model the clinical setting properly. Here we investigate whether PAT is superior to the current clinical ‘gold standard’ for treating poststroke infections. Therefore, we modeled stroke care according to the current stroke guidelines recommending early antibiotic treatment after diagnosing infections. To reliably diagnose pneumonia in living mice, we established a general health score and a magnetic resonance imaging protocol for radiologic confirmation. Compared with standard treatment after diagnosis by these methods, PAT not only abolished pneumonia successfully but also improved general medical outcome. Both, preventive and standard antibiotic treatment using enrofloxacin improved survival in a similar way compared with placebo treatment. However, in contrast to standard treatment, only PAT improved functional outcome assessed by gait analysis. In conclusion, standard and preventive treatment approach reduced poststroke mortality, however at the cost of a worse neurologic outcome compared with preventive approach. These data support the concept of PAT for treating patients at risk for poststroke infections and warrant phase III trials to prove this concept in clinical setting.
State-specific heavy-atom effect on intersystem crossing processes in 2-thiothymine: A potential photodynamic therapy photosensitizer
Authors: Cui Ganglong , Fang Wei-hai
Published: January 2013

Thiothymidine has a potential application as a photosensitizer in cancer photodynamic therapy (PDT). As the chromophore of thiothymidine, 2-thiothymine exhibits ultrahigh quantum yield of intersystem crossing to the lowest triplet state T1 (ca. 100%), which contrasts with the excited-state behavior of the natural thymine that dissipates excess electronic energy via ultrafast internal conversion to the ground state. In this work, we employed high-level complete-active space self-consistent field and its second-order perturbation methods to explore the photophysical mechanism of a 2-thiothymine model. We have optimized the minimum energy structures in the low-lying seven electronic states, as well as ten intersection points. On the basis of the computed potential energy profiles and spin-orbit couplings, we proposed three competitive, efficient nonadiabatic pathways to the lowest triplet state T1 from the initially populated singlet state S2. The suggested mechanistic scenario explains well the recent experimental phenomena. The origin responsible for the distinct photophysical behaviors between thymine and 2-thiothymine is ascribed to the heavy-atom effect, which is significantly enhanced in the latter. Additionally, this heavy-atom effect is found to be state-specific, which could in principle be used to tune the photophysics of 2-thiothymine. The present high-level electronic structure calculations also contribute to understand the working mechanism of thiothymidine in PDT.
Critical-temperature/Peierls-stress dependent size effects in body centered cubic nanopillars
Authors: Min Han Seung , Feng Gang , Young Jung Joo , Joon Jung Hee , Groves James R. , Nix William D. , Cui Yi
Published: January 2013

The size-dependent plasticity of body centered cubic (bcc) metals is different from face centered cubic (fcc) metals: the size-effect exponent n varies for different bcc metal nanopillars (n = 0.8–1.0 for V, Nb; n = 0.3–0.5 for Ta, Mo, W). This inconsistency is first explained through a simple model based on the temperature-dependent Peierls stress. The bcc V nanopillars with a low critical temperature and Peierls stress showed a fcc-like size effect with n = 0.79, and our in-situ TEM compression study revealed that fcc-like dislocation starvation occurred in bcc V nanopillars, indicating that a small Peierls stress in V contributes to the fcc-like behavior.
Structure evolution and entropy change of temperature and magnetic field induced magneto-structural transition in Mn1.1Fe0.9P0.76Ge0.24
Authors: Yue Ming , Liu Danmin , Huang Qingzhen , Wang Tong , Hu Fengxia , Li Jingbo , Rao Guanghui , Shen Baogen , Lynn Jeffery W. , Zhang Jiuxing
Published: January 2013

The compound Mn1.1Fe0.9P0.76Ge0.24 has been studied using neutron powder diffraction (NPD), differential scanning calorimeter (DSC), and magnetic measurements, in order to clarify the nature of the magnetic and structural transition and measure the associated entropy change (ΔS). The strongly first order transition occurs from a paramagnetic (PM) to a ferromagnetic (FM) phase and can be induced either by temperature or by an applied magnetic field. Our investigations indicate that the two processes exhibit identical evolutions regarding the crystal and magnetic structures, indicating they should have the same entropy change. We, therefore, conclude that the ΔSDSC obtained by the DSC method (where the transition is temperature induced) is valid also for the magnetically induced transition, thus avoiding uncertainties connected with the magnetic measurements. We have obtained the ΔSDSC = 33.8 J/kg · K for this sample upon cooling, which would increase to 42.7 J/kg · K for a impurity-free and completely homogeneous sample. For comparison, the magnetic entropy changes (ΔSM) induced by magnetic field and calculated using the Maxwell relation yields a ΔSM = 46.5J/kg · K, 38% higher than ΔSDSC. These entropy results are compared and discussed.
Carrier density dependence of the magnetic properties in iron-doped Bi2Se3 topological insulator
Authors: Li H. , Song Y. R. , Yao Meng-Yu , Zhu Fengfeng , Liu Canhua , Gao C. L. , Jia Jin-Feng , Qian Dong , Yao X. , Shi Y. J. , Wu D.
Published: January 2013

The electronic and magnetic properties of iron-doped topological insulator Bi1.84−xFe0.16CaxSe3 single crystals were studied. By co-doping Fe and Ca atoms, ferromagnetic bulk states with different carrier density (from n-type to p-type) were obtained. Effective magnetic moments for each Fe atom was estimated as small as about 0.07μB. Magnetic and non-magnetic phases separation was observed in all samples. Our results suggest that the bulk ferromagnetism in Fe-doped Bi2Se3 is not intrinsic and regardless of carrier density.
Construction and performance of a dilution-refrigerator based spectroscopic-imaging scanning tunneling microscope
Authors: Singh U. R. , Enayat M. , White S. C. , Wahl P.
Published: January 2013

We report on the set-up and performance of a dilution-refrigerator based spectroscopic imaging scanning tunneling microscope. It operates at temperatures below 10 mK and in magnetic fields up to 14T. The system allows for sample transfer and in situ cleavage. We present first-results demonstrating atomic resolution and the multi-gap structure of the superconducting gap of NbSe2 at base temperature. To determine the energy resolution of our system we have measured a normal metal/vacuum/superconductor tunneling junction consisting of an aluminum tip on a gold sample. Our system allows for continuous measurements at base temperature on time scales of up to ≈170 h.
Classification of the ejection mechanisms of charged macromolecules from liquid droplets
Authors: Consta Styliani , Malevanets Anatoly
Published: January 2013

The relation between the charge state of a macromolecule and its ejection mechanism from droplets is one of the important questions in electrospray ionization methods. In this article, effects of solvent-solute interaction on the manifestation of the charge induced instability in a droplet are examined. We studied the instabilities in a prototype system of a droplet comprised of charged poly(ethylene glycol) and methanol, acetonitrile, and water solvents. We observed instances of three, previously only conjectured, [S. Consta, J. Phys. Chem. B 114, 5263 (2010)10.1021/jp912119v] mechanisms of macroion ejection. The mechanism of ejection of charged macroion in methanol is reminiscent of “pearl” model in polymer physics. In acetonitrile droplets, the instability manifests through formation of solvent spines around the solvated macroion. In water, we find that the macroion is ejected from the droplet through contiguous extrusion of a part of the chain. The difference in the morphology of the instabilities is attributed to the interplay between forces arising from the macroion solvation energy and the surface energy of the droplet interface. For the contiguous extrusion of a charged macromolecule from a droplet, we demonstrate that the proposed mechanism leads to ejection of the macromolecule from droplets with sizes well below the Rayleigh limit. The ejected macromolecule may hold charge significantly higher than that suggested by prevailing theories. The simulations reveal new mechanisms of macroion evaporation that differ from conventional charge residue model and ion evaporation mechanisms.
Analysis of second-harmonic generation by primary horizontal shear modes in layered planar structures with imperfect interfaces
Authors: Deng Mingxi , Xiang Yanxun
Published: January 2013

This paper describes modeling of second-harmonic generation by the primary horizontal shear (SH) mode propagation in layered planar structures with imperfect interfaces. Due to the elastic nonlinearity of the solid, there are second-order bulk driving forces in each solid layer and a second-order stress tensor at each surface/interface, accompanying the primary SH mode propagation. Within second-order perturbation, these bulk driving forces and stress tensors can be thought of as the excitation source of a series of double frequency Lamb modes (DFLMs) in terms of the approach of modal expansion analysis for waveguide excitation. The equation governing the expansion coefficient of each DFLM is developed. It is found that the expansion coefficient of each DFLM is directly coupled with the interfacial properties, characterized by the finite normal and tangential interfacial stiffnesses. Especially, the phase velocity mismatching between the primary SH mode and the DFLM, caused by the degradation of interface (with respect to the case of the perfect interface), can remarkably influence the efficiency of second-harmonic generation by the primary SH mode propagation. The potential is discussed of using the effect of second-harmonic generation by the primary SH mode propagation to evaluate the interfacial properties of layered structures.
Singularity formation and nonlinear evolution of a viscous vortex sheet model
Authors: Sohn Sung-Ik
Published: January 2013

We study Dhanak's model [J. Fluid Mech. 269, 265 (1994)]10.1017/S0022112094001552 of a viscous vortex sheet in the sharp limit, to investigate singularity formations and present nonlinear evolutions of the sheets. The finite-time singularity does not disappear by giving viscosity to the vortex sheet, but is delayed. The singularity in the sharp viscous vortex sheet is found to be different from that of the inviscid sheet in several features. A discontinuity in the curvature is formed in the viscous sheet, similarly as the inviscid sheet, but a cusp in the vortex sheet strength is less sharpened by viscosity. Exponential decay of the Fourier amplitudes is lost by the formation of the singularity, and the amplitudes of high wavenumbers exhibit an algebraic decay, while in the inviscid vortex sheet, the algebraic decay of the Fourier amplitudes is valid from fairly small wavenumbers. The algebraic decay rate of the viscous vortex sheet is approximately −2.5, independent of viscosity, which is the same rate as the asymptotic analysis of the inviscid sheet. Results for evolutions of the regularized vortex sheets show that the roll-up is weakened by viscosity, and the regularization parameter has more significant effects on the fine-structure of the core than does viscosity.
Mechanical properties of bilayer graphene with twist and grain boundaries
Authors: Zhang Junfeng , Zhao Jijun
Published: January 2013

We report the mechanical properties (including intrinsic strength, critical failure strain, and Young's modulus) of bilayer graphene with twist or grain boundaries from first-principles calculations. We find that the intrinsic strength and critical failure strain of a bilayer graphene are governed by the twist angle. If a bilayer graphene is formed by one perfect graphene sheet and another graphene monolayer with grain boundaries, its overall mechanical properties are dominated by the layer with grain boundaries. The larger grain boundary angle in bilayer graphene, the higher intrinsic strength it would possess because of the lower energy and shorter C-C bond lengths on the boundary. Owing to the interlayer van de Waals interaction, bilayer graphene with small grain boundary angle presents different behavior from monolayer graphene grain boundaries.
Electrical and interfacial properties of GaAs/GaSb metal-organic vapour phase epitaxy heterostructures
Authors: Parisini A. , Baldini M. , Gombia E. , Frigeri C. , Jakomin R. , Tarricone L.
Published: January 2013

The electrical properties of GaAs/GaSb heterojunctions grown by metal-organic vapour phase epitaxy were carefully investigated. The structures were formed by heavily p(Zn)-doped GaAs layers deposited on n(Te)-doped GaSb bulk crystal used as substrates. The current-voltage characteristics showed the formation of a GaSb p-n homojunction, which was expected to be induced by Zn diffusion into GaSb. Nevertheless, secondary ion mass spectrometry pointed out a small penetration depth of Zn atoms in the GaSb substrate, resulting unaffected by post-growth annealing processes. Electron beam induced current analysis demonstrated that the p-n junction interface was located more deeply into the substrate (∼1 μm). This result was confirmed by capacitance-voltage (C-V) and electrochemical C-V characterizations. Admittance spectroscopy led to attribute the change of conduction type from n to p in GaSb to the formation of additional shallow acceptor levels, activated by GaAs growth and post-growth thermal annealing processes. An attempt to explain the formation of the buried junction in terms of atomic interdiffusion is provided, in order to justify, from the microscopic point of view, the low diffusivity of Zn in GaSb, and the apparently uncorrelated depth of the p-n junction interface in the substrate.
A facile approach to enhance the high temperature stability of magnetite nanoparticles with improved magnetic property
Authors: Pati S. S. , Philip John
Published: January 2013

We study the effect of Zn2+ doping on crystal structure, magnetic properties, blocking and Curie temperatures, and the high temperature phase stability of magnetite nanoparticles under air and vacuum annealing. The Zn2+ doped nanoparticles (ZnxFe3−xO4 with x = 0, 0.2, 0.4, and 0.6) are prepared by simple co-precipitation technique and are characterized by high temperature X-ray powder diffraction (HTXRD), vibrating sample magnetometer, small angle X-ray scattering, thermogravimetry, differential scanning calorimetry (DSC), and transmission electron microscopy. Our HTXRD studies show that the decomposition temperature of pure magnetite (Fe3O4) in vacuum is increased by 300 °C (from 700 to 1000 °C), with 0.2 fraction of Zn2+ doping. The DSC studies under air environment also show that the γ-Fe2O3 to α-Fe2O3 phase transition temperature increases with the zinc fraction. The increase in transition temperature is attributed to the increase in the activation energy of the maghemite to hematite phase transition after the replacement of Fe3+ with larger diameter Zn2+ in the A site. Interestingly, the saturation magnetization increases from 61 to 69 emu/g upon 0.2 fraction of Zn2+, which augments the utility of the doped compound for practical applications. While the Curie temperature is found to increase with doping concentration, the blocking temperature shows an opposite trend. The blocking temperature values were found to be 262, 196, 144, and 153 K for 0, 0.2, 0.4, and 0.6 fraction of zinc, respectively. The reduction in TB is attributed to weak dipole–dipole interactions and local exchange coupling between nanoparticles. All the Zn2+ doped samples show superparamagnetic nature. These findings are extremely useful in producing superparamagnetic nanoparticles with enhanced magnetic properties for high temperature applications.