bluuebunny/crossref_metadata_2025 huggingface dataset:
Sterbebegleitung in der stationären Altenpflege – Ergebnisse einer Expertenbefragung
Authors: Vogt Dominique
Published: August 2013

Einleitung

Aufgrund der demografischen Entwicklungen haben sich der Sterbeprozess und die Versorgung am Lebensende von alten und hochaltrigen Menschen in die Einrichtungen der stationären Altenpflege verlagert. Dadurch wird das Pflegepersonal häufiger mit Sterbesituationen konfrontiert und vor zusätzliche Herausforderungen gestellt. Ziel einer Expertenbefragung war es, die Gestaltung der Sterbebegleitung und palliativen Versorgung in der stationären Altenpflege vor dem Hintergrund der verkürzten Verweildauer zu analysieren.
Suizid infolge psychischer Erkrankungen
Authors: Haltenhof Horst , Ziegenbein Marc , Sieberer Marcel
Published: August 2013

Einleitung

Suizidales Verhalten hat es in der Menschheitsgeschichte schon immer gegeben. Dieser Beitrag liefert einen Überblick zur Suizidalität im Kontext psychischer Erkrankungen.
Luminescence chronology of the inland sand dunes from SE India
Authors: Reddy Dontireddy Venkat , Singaraju Vuddaraju , Mishra Rakesh , Kumar Devender , Thomas Puthusserry Joseph , Rao Karra Kameshwa , Singhvi Ashok Kumar
Published: August 2013

Records of past climate changes have been preserved variously on the earth's surface. Sand dunes are one such prominent imprint, and it is suggested that their presence is an indicator of periods of transition from arid to less arid phases. We report inland sand dunes from Andhra Pradesh (SE India) spread over an area of ~ 500 km2, ~ 75 km inland from the east coast. The dune sands are examined to understand their provenance, transportation, timing of sand aggradation and their relationship to past climates. The dune distribution, grain morphology and the grain-size studies on sands suggest an aeolian origin. Physiography of the study area, heavy mineral assemblage, and abundance of quartz in the parent rocks indicate that the dune sands are largely derived from first-order streams emanating from hills in the region and from weathering of the Nellore schist belt. It appears that the geomorphology and wind direction pattern both facilitated and restricted the dune aggradation and preservation to a limited area. OSL dating of 47 dune samples ranged from the present to ~ 50 ka, thereby suggesting a long duration of sand-dune aggradation and/or reworking history.
Globalization and the Near East: A Study of Cotton Market Integration in Egypt and Western Anatolia
Authors: Panza Laura
Published: August 2013

The Near East underwent a process of integration with the global economy during the second half of the nineteenth century. This article explores one aspect of this process, examining the linkages established between the cotton industries in Egypt and Western Anatolia, and the international cotton market during the first wave of globalization. We undertake a quantitative exploration of the pattern of price transmission between the Near East and the international cotton markets over this period, connecting changes in the nature of spatial market integration to major economic and political developments.
Genetic and genomic approaches for the discovery of parasite genes involved in antimalarial drug resistance
Authors: MWANGI JONATHAN M. , RANFORD-CARTWRIGHT LISA C.
Published: August 2013

The biggest threat to the war on malaria is the continued evolution of drug resistance by the parasite. Resistance to almost all currently available antimalarials now exists inPlasmodium falciparumwhich causes the most suffering among all human malaria parasites. Monitoring of antimalarial efficacy and the development and subsequent spread of resistance has become an important part in the treatment and control of malaria. With recent reports of reduced efficacy of artemisinin, the current recommended treatment for uncomplicated malaria, there is urgent need for better methods to recognize and monitor drug resistance for effective treatment. Molecular markers have become a welcome addition to complement the more laborious and costlyin vitroandin vivomethods that have traditionally been used to monitor drug resistance. However, there are currently no molecular markers for resistance to some antimalarials. This review highlights the role of the various genetic and genomic approaches that have been used in identifying the molecular markers that underlie drug resistance inP. falciparum. These approaches include; candidate genes, genetic linkage and genome-wide association studies. We discuss the requirements and limitations of each approach and use various examples to illustrate their contributions in identifying genomic regions of the parasite associated with antimalarial drug responses.
Barriers to mental health treatment: results from the WHO World Mental Health surveys
Authors: Andrade L. H. , Alonso J. , Mneimneh Z. , Wells J. E. , Al-Hamzawi A. , Borges G. , Bromet E. , Bruffaerts R. , de Girolamo G. , de Graaf R. , Florescu S. , Gureje O. , Hinkov H. R. , Hu C. , Huang Y. , Hwang I. , Jin R. , Karam E. G. , Kovess-Masfety V. , Levinson D. , Matschinger H. , O'Neill S. , Posada-Villa J. , Sagar R. , Sampson N. A. , Sasu C. , Stein D. J. , Takeshima T. , Viana M. C. , Xavier M. , Kessler R. C.
Published: August 2013

Background

To examine barriers to initiation and continuation of mental health treatment among individuals with common mental disorders.

Method

Data were from the World Health Organization (WHO) World Mental Health (WMH) surveys. Representative household samples were interviewed face to face in 24 countries. Reasons to initiate and continue treatment were examined in a subsample (n = 636 78) and analyzed at different levels of clinical severity.

Results

Among those with a DSM-IV disorder in the past 12 months, low perceived need was the most common reason for not initiating treatment and more common among moderate and mild than severe cases. Women and younger people with disorders were more likely to recognize a need for treatment. A desire to handle the problem on one's own was the most common barrier among respondents with a disorder who perceived a need for treatment (63.8%). Attitudinal barriers were much more important than structural barriers to both initiating and continuing treatment. However, attitudinal barriers dominated for mild-moderate cases and structural barriers for severe cases. Perceived ineffectiveness of treatment was the most commonly reported reason for treatment drop-out (39.3%), followed by negative experiences with treatment providers (26.9% of respondents with severe disorders).

Conclusions

Low perceived need and attitudinal barriers are the major barriers to seeking and staying in treatment among individuals with common mental disorders worldwide. Apart from targeting structural barriers, mainly in countries with poor resources, increasing population mental health literacy is an important endeavor worldwide.
Moving beyond ‘ageing in place’: older people's dislikes about their home and neighbourhood environments as a motive for wishing to move
Authors: HILLCOAT-NALLÉTAMBY SARAH , OGG JIM
Published: August 2013

Ageing in place has been promoted by policy makers as the optimal residential solution for later life, premised on older people's reluctance to contemplate relocation, their declining residential mobility and high levels of residential satisfaction. This paper takes a critical perspective to the notion of ageing in place by examining older people's dislikes about, rather than levels of satisfaction with their home and neighbourhood environments, and establishing whether such dislikes influence a desire to move. Analysis of the 2004 Living in Wales Survey shows that despite high levels of residential satisfaction, a significant proportion of older people do wish to move. Logistic regression results indicate this desire is strongly associated with dislikes about their immediate home environment, more than neighbourhood factors. Contemplating a move in later life may be shaped more by a desire to ‘attach’ to people, than to remain in situ to preserve an attachment to place.
Use of AIS Data to Characterise Marine Traffic Patterns and Ship Collision Risk off the Coast of Portugal
Authors: Silveira P.A.M. , Teixeira A.P. , Soares C. Guedes
Published: August 2013

This paper studies the risk of ship collision off the coast of Portugal based on Automatic Identification System (AIS) data, which is recorded and maintained by the Portuguese coastal Vessel Traffic Service (VTS) control centre (CCTMC). Computer programs for decoding, visualization and analysis of the AIS data have been developed. From analysis of the AIS data available, maritime traffic off the coast of Portugal is characterized and a statistical analysis of traffic in the Traffic Separation Schemes is provided. An algorithm has been developed to assess the risk profile and the relative importance of routes associated with ports. A method is proposed to calculate the collision risk from the assessment of the number of collision candidates by estimating future distances between ships based on their previous positions, courses and speeds, and comparing those distances with a defined collision diameter. Values of causation probability suggested in several studies are used to calculate the expected number of collisions in the period of time under investigation based on the number of collision candidates. The results of this study are then compared with the number of collisions that have occurred between 1997–2006, registered and maintained by the Portuguese Maritime Authority.
Non-extractable polyphenols, a major dietary antioxidant: occurrence, metabolic fate and health effects
Authors: Pérez-Jiménez Jara , Díaz-Rubio M. Elena , Saura-Calixto Fulgencio
Published: August 2013

Current research on dietary antioxidants misses the so-called non-extractable polyphenols (NEPP), which are not significantly released from the food matrix either by mastication, acid pH in the stomach or action of digestive enzymes, reaching the colon nearly intact. NEPP, not detected by the usual analytical procedures, are made up of macromolecules and single phenolic compounds associated with macromolecules. Therefore, NEPP are not included in food and dietary intake data nor in bioavailability, intervention or observational studies. The present paper aims to provide an overview of dietary NEPP – nature, occurrence in diet, metabolic fate and possible health effects. NEPP are a relevant fraction of dietary polyphenols exerting their main biological action in the colon, where they are extensively fermented by the action of microbiota, giving place to absorbable metabolites. NEPP exhibit different potential health-related properties, in particular in relation to gastrointestinal health, such as increases in antioxidant and antiproliferative capacities, reduction of intestinal tumorigenesis and modification of gene expression, as observed in different animal models. Further research into NEPP may provide a better understanding of the health effects of dietary antioxidants.
Nutritional strategies to counteract muscle atrophy caused by disuse and to improve recovery
Authors: Magne Hugues , Savary-Auzeloux Isabelle , Rémond Didier , Dardevet Dominique
Published: August 2013

Periods of immobilisation are often associated with pathologies and/or ageing. These periods of muscle disuse induce muscle atrophy which could worsen the pathology or elderly frailty. If muscle mass loss has positive effects in the short term, a sustained/uncontrolled muscle mass loss is deleterious for health. Muscle mass recovery following immobilisation-induced atrophy could be critical, particularly when it is uncompleted as observed during ageing. Exercise, the best way to recover muscle mass, is not always applicable. So, other approaches such as nutritional strategies are needed to limit muscle wasting and to improve muscle mass recovery in such situations. The present review discusses mechanisms involved in muscle atrophy following disuse and during recovery and emphasises the effect of age in these mechanisms. In addition, the efficiency of nutritional strategies proposed to limit muscle mass loss during disuse and to improve protein gain during recovery (leucine supplementation, whey proteins, antioxidants and anti-inflammatory compounds, energy intake) is also discussed.
Distribution modelling of Eleonora’s Falcon Falco eleonorae Géné, 1839 occurrence in its wintering grounds: a niche-based approach with satellite telemetry data
Authors: KASSARA CHRISTINA , FRIC JAKOB , SFENTHOURAKIS SPYROS
Published: August 2013

Eleonora’s Falcon is a long-distance migrant of the Palearctic region. In recent years, the advent of satellite telemetry has enabled a more detailed investigation of the species’s migratory and wintering periods. In this study, we model the distribution pattern of four Eleonora’s Falcons originating from Greece within their wintering grounds in Madagascar with the use of satellite telemetry data and a niche-based technique, Maxent. The model predicted few highly suitable areas for the occurrence of the species, restricted to elevated areas receiving large amounts of precipitation during the wintering period, containing patches of primary and degraded humid submontane forests as well as cultivation. Most of these areas occurred within the previously estimated home ranges of the four falcons, as well as of three falcons from another independent study. Taking into account the ongoing alterations in landscape structure that occur within the eastern rainforest region of Madagascar, we believe that it is imperative to better understand the ecological requirements of Eleonora’s Falcon. To this end, we recommend the application of Maxent in the study of habitat selection of the species that could be further refined with the inclusion of biotic interactions and seasonal resource availability.
The seasonal demand for multiple monies in Manchuria: re-examining Zhang Zuolin's government's economic policy during the 1920s
Authors: Kaminishi Miriam
Published: August 2013

This article reviews the political economy of Manchuria under the rule of Zhang Zuolin, which resulted in the economic instability that occurred during the winter of 1928. One can conjecture that the economic instability did not occur only because of the arbitrariness of the political and military regional government. The instability appears to be related to an ongoing seasonal demand for monies, which was relatively high between the months of September and March, since it corresponded to the period of commerce in soybeans − the region's main economic activity −, the migration of seasonal workers, and also the festive period of the Chinese New Year. The analysis was conducted based on primary materials published by the South Manchuria Railway Company, such as currency issuance and the variation of the exchange rate of the major currencies in circulation among foreign and Chinese currencies.
A syntactic approach for opinion mining on Spanish reviews
Authors: VILARES DAVID , ALONSO MIGUEL A. , GÓMEZ-RODRÍGUEZ CARLOS
Published: August 2013

We describe an opinion mining system which classifies the polarity of Spanish texts. We propose an NLP approach that undertakes pre-processing, tokenisation and POS tagging of texts to then obtain the syntactic structure of sentences by means of a dependency parser. This structure is then used to address three of the most significant linguistic constructions for the purpose in question: intensification, subordinate adversative clauses and negation. We also propose a semi-automatic domain adaptation method to improve the accuracy of our system in specific application domains, by enriching semantic dictionaries using machine learning methods in order to adapt the semantic orientation of their words to a particular field. Experimental results are promising in both general and specific domains.
‘Rules as Strict as Palestrina's’: The Regulation of Pitch and Rhythm in Ligeti's Requiem andLux aeterna
Authors: LEVY BENJAMIN R.
Published: August 2013

György Ligeti has stated that his micropolyphonic compositions were ‘governed by rules as strict as Palestrina's’ (Ligeti 1983, 14); some of these rules are preserved directly in his sketches and others can be derived from the compositions themselves. This article discusses the artistic context in which Ligeti developed systems of rules for individual compositions, and investigates in depth the composer's rules for the organization of pitch and rhythm in two of his seminal works from the 1960s, transmitting the explicit rules for pitch in sketches for the ‘De die judicii’ movement of the Requiem and uncovering implicit rules for rhythm inLux aeterna. By examining both the rules and their application in composition, with the exceptions that arise therein, we come to a better understanding of the aesthetic goals Ligeti's rules were devised to meet, and the balance of stricture and freedom that was essential to the composer's persona.
Republicans, Catholics and the West: Explaining the Strength of Religious School Aid Prohibitions
Authors: Hackett Ursula
Published: August 2013

In the current polarized political climate there is heightened attention paid to the American state constitutional provisions known as “Blaine Amendments” or “No-Aid Provisions” that were passed between 1835 and 1959 to prohibit public aid to religious schools. Judgments about No-Aid Provisions have largely been made by scholars on anad hocbasis using narrative-based historical accounts, emotive language and without clear classificatory criteria. Using content analysis this article constructs the first quantitative scale of No-Aid Provision strength and subjects it to statistical treatment to explain why some prohibitions are much stronger than others. It finds that larger Catholic populations, Republican dominance, and Federal Enabling Acts make No-Aid language more strident. In so doing this article adjudicates between competing explanations for No-Aid Provision strength in a way that illuminates the interaction of politics, religion and education in America.
An injectable hyaluronic acid/PEG hydrogel for cartilage tissue engineering formed by integrating enzymatic crosslinking and Diels–Alder “click chemistry”
Authors: Yu Feng , Cao Xiaodong , Li Yuli , Zeng Lei , Yuan Bo , Chen Xiaofeng
Published: August 2013

Injectable HA/PEG hydrogel was crosslinked by integrating the enzymatic crosslinking and Diels–Alder click chemistry and showed excellent shape recovery and anti-fatigue properties at a high compressive stress.
Controllability of fractional dynamical systems with prescribed controls
Authors: Krishnan Balachandran , Jayakumar Kokila
Published: August 2013

The present study deals with the controllability results for fractional dynamical systems with prescribed controls. Sufficient conditions for the controllability results of non‐linear fractional dynamical systems are obtained using Schauder's fixed point theorem and fractional calculus. Illustrative examples are presented.
Stability analysis for control systems with aperiodically sampled data using an augmented Lyapunov functional method
Authors: Zhang Chuan‐Ke , Jiang Lin , He Yong , Wu Henry , Wu Min
Published: August 2013

This study analyses the stability of aperiodically sampled‐data control systems with and without communication delays by using a new augmented Lyapunov functional method. Compared with most of existing methods that commonly require each term of a Lyapunov–Krasovskii functional (LKF) to be non‐negative, the proposed method waives this requirement by introducing an augmented term, which has zero value and zero derivative, into the LKF. Several stability criteria with less conservatism are obtained from the relaxation of constraint conditions for guaranteeing the non‐negativeness of the LKF. These criteria are extended to investigate the stability of the systems with polytopic uncertainties and the exponential stability of the system. Three numerical examples are given to show the effectiveness of the proposed method.
Robust consensus tracking of multi‐agent systems with uncertain Lur'e‐type non‐linear dynamics
Authors: Zhao Yu , Duan Zhisheng , Wen Guanghui , Chen Guanrong
Published: August 2013

This study addresses the robust consensus tracking problem of multi‐agent systems with uncertain Lur'e‐type non‐linear dynamics under a fixed topology. To achieve consensus tracking, a class of discontinuous control protocols are first proposed, which rely on the relative information among the neighbouring agents. Theoretical analysis indicates that the robust consensus tracking of uncertain Lur'e network can be achieved if the coupling strength and the control gain are both larger than the thresholds depending on some global information of the network. Then, an adaptive consensus tracking protocol is further designed to solve the robust consensus tracking problem as a modification of a fully distributed version without the need of any global information of the multi‐agent systems. Furthermore, as an expansion of the discontinuous protocols, a new class of continuous control laws are developed based on the boundary layer concept. Finally, a couple of examples are given to illustrate the effectiveness of the theoretical results.
Compensation mechanism of polarization-independent reflection structure based on two magneto-optical crystals and two mirrors
Authors: Zhao Guhao , Zhao Shanghong , Yao Zhoushi , Hao ChenLu , Meng Wen , Wang Xiang , Zhu Zhihang , Liu Feng
Published: August 2013

We provide, to our knowledge, the first experimental demonstration of polarization-independent reflection structure, which is based on two magneto-optical crystals with 90° rotatory angles and two mirrors without depolarization. The experiment shows that the polarization fidelity achieved about 99.98%. We also find out that even the rotatory angles of magneto-optical crystals are not 90°, when the two rotatory angles are near to 90°, the closer they are, the higher polarization fidelity is. This characteristic can be very important and useful for engineering implementation. It is also approved in theory and experiment.
Reexamination of thermal transport measurements of a low-thermal conductance nanowire with a suspended micro-device
Authors: Weathers Annie , Bi Kedong , Pettes Michael T. , Shi Li
Published: August 2013

An increasingly used technique for measuring the thermal conductance of a nanowire is based on a suspended micro-device with built-in resistance thermometers. In the past, the technique has been limited to samples with thermal conductance larger than 1 × 10−9 W/K because of temperature fluctuations in the sample environment and the presence of background heat transfer through residual gas molecules and radiation between the two thermometers. In addition, parasitic heat loss from the long supporting beams and asymmetry in the fabricated device results in two additional errors, which have been ignored in previous use of this method. To address these issues, we present a comprehensive measurement approach, where the device asymmetry is determined by conducting thermal measurements with two opposite heat flow directions along the nanowire, the background heat transfer is eliminated by measuring the differential heat transfer signal between the nanowire device and a reference device without a nanowire sample, and the parasitic heat loss from the supporting beams is obtained by measuring the average temperature rise of one of the beams. This technique is demonstrated on a nanofiber sample with a thermal conductance of 3.7 × 10−10 W/K, against a background conductance of 8.2 × 10−10 W/K at 320 K temperature. The results reveal the need to reduce the background thermal conductance in order to employ the micro-device to measure a nanowire sample with the thermal conductance less than 1 × 10−10 W/K.
Resonant frequency and damping of a coupled resonant system measured by apparent dissipation factor frequency spectra
Authors: Zuo Wenlong , Li Longfei , Yang Yuebin , Chen Lan , Zhang Jinxiu , Xiong Xiaomin
Published: August 2013

This paper proposes a novel scheme to study the resonance of a vibration mode of a complex system by investigating the apparent dissipation factor frequency spectrum (ADFFS) of another coupled vibration mode. We demonstrate that the resonant absorption peak in ADFFS of one vibration mode is proportional to the displacement amplitude square of another coupled vibration mode from both energy dissipation and dynamics. Two coupled micro-cantilevers are experimentally shown that the ADFFS of one micro-cantilever could be applied to obtain the resonant frequency and the damping of the other coupled micro-cantilever.
A scripted control system for autonomous hardware-timed experiments
Authors: Starkey P. T. , Billington C. J. , Johnstone S. P. , Jasperse M. , Helmerson K. , Turner L. D. , Anderson R. P.
Published: August 2013

We present the labscript suite, an open-source experiment control system for automating shot-based experiments and their analysis. Experiments are composed as Python code, which is used to produce low-level hardware instructions. They are queued up and executed on the hardware in real time, synchronized by a pseudoclock. Experiment parameters are manipulated graphically, and analysis routines are run as new data are acquired. With this system, we can easily automate exploration of parameter spaces, including closed-loop optimization.
A generic π* shape resonance observed in energy-dependent photoelectron angular distributions from two-colour, resonant multiphoton ionization of difluorobenzene isomers
Authors: Staniforth Michael , Daly Steven , Reid Katharine L. , Powis Ivan
Published: August 2013

We present new evidence for the existence of a near threshold π* shape resonance as a common feature in the photoionization of each isomer of difluorobenzene. Experimentally, this is revealed by significant changes in the anisotropy of the photoelectron angular distributions (PADs) following the ionization of the optically aligned S1 state of these molecules at varying photon energies. Continuum multiple scattering Xα calculations reproduce this behaviour well, and allow the visualisation of the continuum shape resonances. The resonances are unusually narrow in energy (<1 eV), but nevertheless appear to extend right down to the ionization thresholds—exactly the low energy range typically accessed in laser-based resonance enhanced multiphoton ionization (REMPI) schemes. The anticipation of such pronounced energy dependence in the PADs and cross-sections sought for other molecules, and an ability to accurately predict such features, should be important for the reliable application and interpretation of experiments involving REMPI probing of those molecules.
Problem of nonlinear coupled electromagnetic TE-TE wave propagation
Authors: Smirnov Yury G. , Valovik Dmitry V.
Published: August 2013

Propagation of two TE coupled electromagnetic waves in a nonlinear plane layer is considered. Nonlinearity in the layer is described by Kerr law. It is shown that a new nonlinear propagation regime exists for a pair of TE waves. The physical problem is reduced to a nonlinear two-parameter eigenvalue problem for a system of (nonlinear) ordinary differential equations. It is proved that TE and TE waves that form a (nonlinear) coupled TE-TE wave can propagate at different frequencies ω1, ω2 with different propagation constants γ1, γ2, respectively. These frequencies can be chosen independently. The existence of a surface coupled TE-TE wave is proved. Intervals of localization of coupled eigenvalues are found.
Investigation of ferroelectric properties and structural relaxation dynamics of polyvinylidene fluoride thin film via second harmonic generation
Authors: Jones J. , Zhu L. , Tolk N. , Mu R.
Published: August 2013

Second harmonic generation (SHG) laser spectroscopy has been demonstrated to be a powerful, sensitive, and non-destructive analytical technique to study crystalline phases, domain and molecular dipole orientations, and relaxation dynamics of ferroelectric polymeric thin films of polyvinylidene fluoride (PVDF). SHG also provides the detailed information at molecular levels and properties at interfaces. The current study of single layered PVDF polymer has shown that SHG can be further developed into an in situ, sensitive and quantitative tool to study ferroelectric polymeric thin film structures. We have used SHG to illustrate the decoupled so called αc− and β− relaxation dynamics processes in PVDF systems.
Extending the 3ω method: Thermal conductivity characterization of thin films
Authors: Bodenschatz Nico , Liemert André , Schnurr Sebastian , Wiedwald Ulf , Ziemann Paul
Published: August 2013

A lock-in technique for measurement of thermal conductivity and volumetric heat capacity of thin films is presented. The technique is based on the 3ω approach using electrical generation and detection of oscillatory heat along a thin metal strip. Thin films are deposited onto the backside of commercial silicon nitride membranes, forming a bilayer geometry with distinct thermal parameters. Stepwise comparison to an adapted heat diffusion model delivers these parameters for both layers. Highest sensitivity is found for metallic thin films.
Plasmon hybridization model generalized to conductively bridged nanoparticle dimers
Authors: Liu Lifei , Wang Yumin , Fang Zheyu , Zhao Ke
Published: August 2013

Charge transfer introduced by a conductive junction bridging a nanoparticle dimer can have a pronounced effect on the optical properties of the system. We have extended the plasmon hybridization model to include conductive junctions and charge transfer effects. From our model, we are able to derive all the plasmon resonances of the bridged dimer, including the charge transfer plasmon (CTP), and predict their trends when system parameters are varied. In particular, we find that CTP is a result of a sufficiently narrow monopole mode interacting with multipolar (including dipolar) modes. The screening arising from charge transfer induces a blueshift of the hybridized bonding dimer modes and decreases the electric field in the junction. Our model may serve as an important guide for optical properties of bridged nanoparticle aggregates.
How to spoil a good basis set for Rayleigh-Ritz calculations
Authors: Pupyshev Vladimir I. , Montgomery H. E.
Published: August 2013

For model quantum mechanical systems such as the harmonic oscillator and a particle in an impenetrable box, we consider the set of exact discrete spectrum functions and define the modified basis set by subtraction of the ground state wavefunction from all the other wavefunctions with some real weights. It is demonstrated that the modified set of functions is complete in the space of square integrable functions if and only if the series of the squared weights diverges. A similar, but nonequivalent criterion is derived for convergence of Rayleigh-Ritz ground state energy calculations to the exact ground state energy value with the basis set extension. Some numerical illustrations are provided which demonstrate a wide variety of possible situations for model systems.
Impact ionization of nitrogen in 4H- and 6H-SiC
Authors: Sankin V. I. , Petrov A. G. , Kaliteevski M.
Published: August 2013

A natural superlattice (NSL) in silicon carbide polytypes induces a miniband structure within the conduction band along the NSL axis C. It was found that the presence of NSL leads to an anisotropy of a nitrogen impurity impact ionization in SiC. For an electric field direction F∥C, the nitrogen impurity breakdown at temperature 4.2 K has not been observed up to the field 1.6 MV/cm for the polytype 6H-SiC. However, for the polytype 4H-SiC dependence breakdown field on impurity concentration demonstrates its usual behavior, which has also been observed for other semiconductor materials. Therewith, the impurity breakdown at the electric field perpendicular to the axis in 4H- and 6H-SiC demonstrates consistency with traditional conceptions. These results are explained theoretically.
Role of positively charged dust grains on dust acoustic wave propagation in presence of nonthermal ions
Authors: Sarkar Susmita , Maity Saumyen
Published: August 2013

An expression for ion current flowing to the dust grains is proposed, when dust charge is positive and the ions are nonthermal. Secondary electron emission has been considered as the source of positive charging of the dust grains. Investigation shows that presence of positively charged dust grains along with thermal electrons and nonthermal ions generate purely growing dust acoustic waves for both the cases of ion nonthermal parameter greater than one and less than one. In the later case, the growth is conditional.
Linear study of Rayleigh-Taylor instability in a diffusive quantum plasma
Authors: Momeni Mahdi
Published: August 2013

The linear Rayleigh-Taylor (RT) instability in an incompressible quantum plasma is investigated on the basis of quantum magnetohydrodynamic model. It is shown that the occurrence of RT instability depends on density-temperature inhomogeneity (characteristic lengths) on one hand, and the system layer size on the other. It is also observed that the combined effects of external magnetic field, diffusivity, and quantum pressure significantly modify the dispersion properties of system in both the parallel and perpendicular directions. For any case, the imaginary and real parts of dispersion relation are presented and the possibility and conditions for the instability growth rate are discussed.
Redox reactions with empirical potentials: Atomistic battery discharge simulations
Authors: Dapp Wolf B. , Müser Martin H.
Published: August 2013

Batteries are pivotal components in overcoming some of today's greatest technological challenges. Yet to date there is no self-consistent atomistic description of a complete battery. We take first steps toward modeling of a battery as a whole microscopically. Our focus lies on phenomena occurring at the electrode-electrolyte interface which are not easily studied with other methods. We use the redox split-charge equilibration (redoxSQE) method that assigns a discrete ionization state to each atom. Along with exchanging partial charges across bonds, atoms can swap integer charges. With redoxSQE we study the discharge behavior of a nano-battery, and demonstrate that this reproduces the generic properties of a macroscopic battery qualitatively. Examples are the dependence of the battery's capacity on temperature and discharge rate, as well as performance degradation upon recharge.
Analog and bipolar resistive switching in pn junction of n-type ZnO nanowires on p-type Si substrate
Authors: Chang Lee Seung , Hu Quanli , Baek Yoon-Jae , Jin Choi Young , Jung Kang Chi , Ho Lee Hyun , Yoon Tae-Sik
Published: August 2013

A pn junction consisting of n-type ZnO nanowires (NWs) on p-type Si substrate exhibits analog resistive switching dependent on the polarity of applied voltage before forming operation for the bipolar switching. The current-voltage curves of Ti/ZnO-NWs/ZnO-seed-layer/p+-Si substrate show diode characteristics with hysteresis in the reverse bias condition, presenting a gradually increasing and then saturated current with repeated voltage sweeps. The current is then further increased with sweeping –V and decreased during the subsequent +V sweep. This polarity-dependent analog switching remains the same during pulse measurement. The analog switching is thought to originate from gradual redistribution of oxygen vacancies, trapping and detrapping of charges in the ZnO NWs, which modulate the depletion width and space charge density. Consequently, the resistance of the pn junction is changed in an analog fashion. After the forming operation, bipolar switching is observed with a transition from high to low resistance states (SET) at +V and reverse transition (RESET) at –V, originating from the formation and rupture of filaments. These results demonstrate multiple features of the ZnO NWs based pn junction, including diode characteristics, analog-type resistive switching before forming operation, and digital-type bipolar switching after forming.
Electrical bistability in monolayers of cobalt-doped ZnO nanocrystals: Effect of alignment of their magnetic domains
Authors: Dey Sukumar , Pal Amlan J.
Published: August 2013

We grow a range of cobalt-doped ZnO nanocrystals, form a monolayer through electrostatic assembly approach, and characterize the nanostructures with a scanning tunneling microscope tip. The scanning tunneling spectroscopy results show electrical bistability, that is, presence of a low- and a high-conducting state, in such monolayers under application of a voltage pulse. The bistability depends on the content of cobalt in the nanocrystals. With the use of such ferromagnetic nanocrystals, we align the magnetization vector of the nanocrystals in a monolayer in order to study the effect of alignment of their magnetic domains on the electrical bistability. We observe that the transport gap of the nanocrystals decreases upon conductance switching. The gap decreases also due to alignment of the magnetic domains of the cobalt-doped nanocrystals. When the magnetically aligned nanocrystals undergo a conductance switching, the transport gap further decreases evidencing a correlation between the electrical bistability and the (change in) transport gap.
Single-photon emission in telecommunication band from an InAs quantum dot grown on InP with molecular-beam epitaxy
Authors: Liu X. , Akahane K. , Jahan N. A. , Kobayashi N. , Sasaki M. , Kumano H. , Suemune I.
Published: August 2013

We report on the experimental demonstration of a single-photon source based on an InAs quantum dot (QD) on InP grown by molecular-beam epitaxy emitting in the telecommunication band. We develop a method to reduce the QD density to prevent inter-dot coupling via tunneling through coupled excited states. A single InAs QD embedded in an as-etched pillar structure exhibits intense and narrow emission lines. Photon antibunching is clearly observed using superconducting single-photon detectors with high sensitivity, and further improvement of the generated single-photon purity is demonstrated with below-barrier-bandgap excitation.
Electrical performance of III-V gate-all-around nanowire transistors
Authors: Razavi Pedram , Fagas Giorgos
Published: August 2013

The performance of III-V inversion-mode and junctionless nanowire field-effect transistors are investigated using quantum simulations and are compared with those of silicon devices. We show that at ultrascaled dimensions silicon can offer better electrical performance in terms of short-channel effects and drive current than other materials. This is explained simply by suppression of source-drain tunneling due to the higher effective mass, shorter natural length, and the higher density of states in the confined channel. We also confirm that III-V junctionless nanowire transistors are more immune to short-channel effects than conventional inversion-mode III-V nanowire field-effect transistors.
Investigation of electrically induced migration of copper on graphene surfaces: Theory and experiments
Authors: Wang Tao , Yu Bin , Liu Yan , Jamal Deen M.
Published: August 2013

We study the physical adsorption of copper (Cu) atoms onto a graphene surface and their movement along an electric field (F) for a single Cu atom or cluster of Cu atoms using density functional theory. The increasing F can be used to overcome physical adsorption Van der Waals force to drive the movement of Cu atoms, rearrange charges in the system and create a fresh balance in which Cu atoms are trapped in other positions. Experiments confirm calculations of Cu atoms moving on graphene. Both calculations and experiments indicate potential reliability issues of the Cu/graphene contact for nanoscale graphene devices.
A simple, tunable, and highly sensitive radio-frequency sensor
Authors: Cui Yan , Sun Jiwei , He Yuxi , Wang Zheng , Wang Pingshan
Published: August 2013

We report a radio frequency (RF) sensor that exploits tunable attenuators and phase shifters to achieve high-sensitivity and broad band frequency tunability. Three frequency bands are combined to enable sensor operations from ∼20 MHz to ∼38 GHz. The effective quality factor (Qeff) of the sensor is as high as ∼3.8 × 106 with 200 μl of water samples. We also demonstrate the measurement of 2-proponal-water-solution permittivity at 0.01 mole concentration level from ∼1 GHz to ∼10 GHz. Methanol-water solution and de-ionized water are used to calibrate the RF sensor for the quantitative measurements.
On collisional diffusion in a stochastic magnetic field
Authors: Abdullaev S. S.
Published: August 2013

The effect of particle collisions on the transport in a stochastic magnetic field in tokamaks is investigated. The model of resonant magnetic perturbations generated by external coils at the plasma edge is used for the stochastic magnetic field. The particle collisions are simulated by a random walk process along the magnetic field lines and the jumps across the field lines at the collision instants. The dependencies of the local diffusion coefficients on the mean free path λmfp, the diffusion coefficients of field lines DFL, and the collisional diffusion coefficients, χ⊥ are studied. Based on these numerical data and the heuristic arguments, the empirical formula, Dr=χ⊥+v||DFL/(1+Lc/λmfp), for the local diffusion coefficient is proposed, where Lc is the characteristic length of order of the connection length lc=πqR0, q is the safety factor, R0 is the major radius. The formula quite well describes the results of numerical simulations. In the limiting cases, the formula describes the Rechester-Rosenbluth and Laval scalings.
Biaxial strain effect on the electronic and magnetic phase transitions in double perovskite La2FeMnO6: A first-principles study
Authors: Qian Yan , Wu Haiping , Kan ErJun , Lu Jian , Lu Ruifeng , Liu Yuzhen , Tan Weishi , Xiao Chuanyun , Deng Kaiming
Published: August 2013

The influence of biaxial strain on both the electronic and magnetic properties in double perovskite La2FeMnO6 is investigated by using density-functional calculations. The results show that La2FeMnO6 exhibits ferromagnetic semiconductor at ambient condition and turns into ferromagnetic half-metal under the whole tensile strain applied in this work, while the compound transfers into ferromagnetic metal under the compressive strain within −8% and into ferrimagnetic semiconductor with the compressive strain beyond −9%. For both ferromagnetic half-metallic and metallic La2FeMnO6, they exhibit very slight change in the electronic states and magnetic moments of the ions, comparing with those of the compound at ambient condition. The electronic configurations of Fe and Mn originating from the high-spin state Fe3+ and intermediate-spin state Mn3+ in ferromagnetic La2FeMnO6 emerge in the low-spin state and high-spin state in ferrimagnetic La2FeMnO6, respectively, when the compressive strain is beyond −9%.
Laterally self-ordered silicon-germanium islands with optimized confinement properties
Authors: Zabel Thomas , Sircar Narayan , Hauke Norman , Zweck Josef , Döblinger Markus , Kaniber Michael , Finley Jonathan J. , Abstreiter Gerhard , Arakawa Yasuhiko , Bougeard Dominique
Published: August 2013

We present an analysis of the electronic confinement properties of self-assembled islands forming via silicon and germanium co-deposition in molecular beam epitaxy. This approach allows the fabrication of laterally self-ordered three dimensional islands in the Stranski-Krastanow growth mode. Using a systematic structural analysis, we derive a realistic fit-parameter free island model for band structure simulations. A comparison between these band structure simulations and photoluminescence spectroscopy shows that such islands have a significant three dimensional spatial electron-hole wave function overlap. In addition, we show that this spatial wave function overlap overcompensates a weak wave function spreading in k-space.
A ferroelastic phase transition in Pb(Zr0.53Ti0.47)O3:Gd
Authors: Portelles J. , Fuentes J. , Durruthy-Rodríguez M. D. , Duarte A. , Raymond O. , Heiras J. , Cruz M. P. , Siqueiros J. M.
Published: August 2013

A study of a new ferroelastic phase transition in Pb(Zr0.53Ti0.47)O3:Gd detected at 144 °C, induced by Gd doping is presented. The existence of such phase transition is barely detectable in the permittivity vs. temperature curve; however, it is made evident through the analyses of the temperature coefficient of the resonant frequency Tkf dependence with temperature in the radial mode resonance spectrum. This coefficient has a sharp discontinuity at around 144 °C. Micro Raman spectra show that the Raman modes associated to Pb/Gd and (Zr/Ti)O6 positioned at 93.6 cm−1 E(1TO) and 144 cm−1 E(1LO) have a minimum in intensity around 140 °C. Besides the modes of the tetragonal structure, there are the modes at 67.3 and 77.8 cm−1 corresponding to a rhombohedral structure, appearing at all temperatures. The Raman intensity vs. temperature plots of the different modes shows a minimum around 140 °C that confirms the ferroelastic transition detected in the resonance spectrum.
Significant thickness dependence of the thermal resistance between few-layer graphenes
Authors: Ni Yuxiang , Chalopin Yann , Volz Sebastian
Published: August 2013

The inter-layer resistance in few layer graphene (FLG) is an unknown intrinsic property that affects the heat removal efficiency of FLG-based thermal devices. Here we present data that demonstrates the layer number dependence of the resistance between FLGs, by using molecular dynamics simulations. The resistance was found to decrease as the layer number increases. FLGs with larger thicknesses are proposed to be advantageous in heat spreading owing to their lower contact resistances. The observed properties do not depend on temperature, which is crucial for FLG based structures to retain a stable heat removal efficiency while working at a large temperature range.
A crowding factor model for the thermal conductivity of particulate composites at non-dilute limit
Authors: Ordonez-Miranda J. , Yang Ronggui , Alvarado-Gil J. J.
Published: August 2013

The effective thermal conductivity models for particulate composites are usually restricted to the dilute limit, with volumetric concentrations of particles typically less than 15%. By considering the particle interactions through a crowding factor, in this work, a new formula is developed to describe the thermal conductivity of composites with a dielectric matrix, for volume fractions of particles up to their maximum packing fraction. The crowding factor model is then applied to analyze two particulate composites with dielectric or metallic particles, where the effects of both interfacial thermal resistance and the electron-phonon coupling are taken into account. It is shown that the predictions of the proposed crowding factor model are larger than the ones predicted by the dilute-limit models, for composites with high volume fractions of particles, due to the particle interactions. The proposed crowding factor model extends the applicability of various thermal conductivity models for composites reported in the literature and its predictions are in good agreement with published experimental data.
Effects of Ga ion-beam irradiation on monolayer graphene
Authors: Wang Quan , Mao Wei , Ge Daohan , Zhang Yanmin , Shao Ying , Ren Naifei
Published: August 2013

The effects of Ga ion on the single layer graphene (SLG) have been studied by Raman spectroscopy (RS), SEM, and field-effect characterization. Under vacuum conditions, Ga ion-irradiation can induce disorders and cause red shift of 2D band of RS, rather than lattice damage in high quality SLG. The compressive strain induced by Ga ion decreases the crystalline size in SLG, which is responsible for the variation of Raman scattering and electrical properties. Nonlinear out-put characteristic and resistance increased are also found in the I-V measurement. The results have important implications during CVD graphene characterization and related device fabrication.