bluuebunny/crossref_metadata_2025 huggingface dataset:
A Delta–Sigma modulator-based heterodyne FMCW radar for short-range applications
Authors: Feger Reinhard , Ng Herman Jalli , Pfeffer Clemens , Stelzer Andreas
Published: March 2014

We present a heterodyne frequency-modulated continuous-wave (FMCW) radar, applicable in short-range applications. Owing to a modulation of the transmit (TX) signal, the intermediate frequency (IF) signal can be shifted away from zero frequency to reduce the influence of dc-offsets and low-frequency disturbances like, e.g. flicker noise existing in components like mixers, amplifiers and analog-to-digital converters. The presented system is based on E-band transceivers realized in SiGe technology, which are fully integrated with antennas in a plastic package. A sinusoidal modulation of the TX signal is realized by a binary phase-shift keying modulator, which is controlled by a Delta–Sigma sequence. The choice of a sinusoidal modulation allows to reuse signal processing blocks which are typically available in FMCW radars. Measurements show that the achievable signal-to-noise ratio is comparable to a homodyne realization since the Delta–Sigma noise can be filtered in the IF stage. Experiments with a bandwidth of 8 GHz demonstrate measurements down to 12 cm with standard deviations of the measured ranges lower than 60 µm. Compared to a homodyne realization the blocking distance could be reduced by approximately 40 mm.
Die Entwicklung und Validierung eines evidenzbasierten Kompetenzmodells effektiver Führung (LEaD: Leadership Effectiveness and Development)
Authors: Schmidt-Huber Marion , Dörr Stefan , Maier Günter W.
Published: March 2014

Die Entwicklung von Führungskräften und die dazu erforderliche Diagnostik von Führungskompetenzen stellen zentrale Inhalte jeder HR-Strategie dar. Viele Unternehmen greifen dabei insbesondere in der Diagnostik auf selbst entwickelte Instrumente zurück, ohne die Vielfalt praxisrelevanter Erkenntnisse der Führungsforschung zu berücksichtigen. Mit dem LEaD-Kompetenzmodell wurde im deutschen Raum einer der ersten Versuche unternommen, den Ansatz des evidenzbasierten Managements auf die Entwicklung eines praxisrelevanten Kompetenzmodells für Führungsaufgaben anzuwenden. Dieser Beitrag beschreibt den Prozess der theoretischen Herleitung und inhaltlichen iterativen Konzeption, skizziert die Inhalte des Kompetenzmodells und berichtet zentrale Ergebnisse der empirischen Studien (Interviewstudie, Prototypizitätsstudie, Pretest und Validierungsstudie). Die Ergebnisse der Validierungsstudie (N = 720) zur Konstrukt- und Kriteriumsvalidierung und inkrementellen Validität zeigen, dass das theoriebasierte Kompetenzmodell und zugehörige Diagnoseinstrument effektives Führungsverhalten reliabel und valide beschreiben und erfassen können.
Familienstatus, mütterliche Belastung, dysfunktionales Erziehungsverhalten und kindliche Auffälligkeiten
Authors: Kliem Sören , Foran Heather , Hahlweg Kurt
Published: March 2014

In der Bundesrepublik Deutschland wächst fast jedes fünfte Kind in einer 1-Elternfamilie auf. Alleinerziehende Mütter und deren Kinder sind dabei häufig von erhöhten psychischen Belastungen bzw. Auffälligkeiten betroffen. Für eine gezielte Unterstützung ist die Kenntnis des Wirkzusammenhangs zwischen dem Familienstatus und der kindliche Belastung von großer Bedeutung. In der vorliegenden Untersuchung soll der Einfluss der mütterlichen Belastung und des dysfunktionalen Erziehungsverhalten im Rahmen einer multiplen Mediationsanalyse überprüft werden. Hierfür wurden die Angaben von n = 60 alleinerziehenden Müttern und n = 219 Müttern aus 2-Elternfamilien analysiert. Es zeigte sich, dass der Einfluss des Familienstatus auf die kindlichen Auffälligkeiten vollständig durch die psychische Belastung der Mütter mediiert wurde; das dysfunktionale Erziehungsverhalten mediierte seinerseits partiell den Zusammenhang der mütterlichen Belastung und der kindlichen Auffälligkeiten. Schlussfolgernd konnten Ansatzpunkte für zielgruppenorientierte Interventionsmaßnahmen identifiziert werden. Diese sollten sich dabei stärker an der elterlichen Belastung und weniger am Familienstatus selbst orientieren.
Zwangsstörungen im Kindes- und Jugendalter
Authors: Jans Thomas , Reichert Andreas
Published: March 2014

Zwangsstörungen zählen mit einer Prävalenz von 1 bis 2 % zu den häufigeren Störungen im Kindes- und Jugendalter. Komorbide Störungen sind regelhaft vorhanden und die psychosozialen Beeinträchtigungen sind oftmals gravierend. Trotz guter Behandelbarkeit der Zwangsstörung gestaltet sich der Langzeitverlauf bei einem bedeutsamen Teil der Betroffenen insgesamt ungünstig. Der vorliegende Beitrag gibt eine selektive Übersicht zu Definition und Klassifikation, Epidemiologie, Symptomatik, Komorbidität, Diagnostik und Verlauf der Zwangsstörung im Jugendalter.
Personal and Vicarious Embarrassability
Authors: Thompson Trevor
Published: March 2014

Although distinct vicarious embarrassability (VE) and personal embarrassability (PE) dimensions have emerged in factor analytic research, few studies have compared theoretically relevant correlates to explore potential differences in underlying mechanisms. The current study sought to determine whether PE was best accounted for by a social evaluation model, and VE by emotional empathy. Four fifty three undergraduates completed embarrassability, emotional empathy, and social evaluation trait measures. Factor analysis with oblique rotation produced two correlated (r = .37) PE and VE factors. Multiple regression did not provide absolute support for two distinct underlying models, with fear of negative evaluation and emotional empathy significant predictors of both embarrassability factors. However, public self-consciousness and perceived social competence were predictive only of PE. These results suggest common mechanisms could underlie PE and VE, but that a negative perception and heightened awareness of one’s social image could confer a unique vulnerability to PE.
Depictions of Injuries and Safety Gear Usage in the World’s Most Popular Video Games
Authors: Karazsia Bryan , Muller Adam
Published: March 2014

Throughout the world, nearly 4 million children die annually as a result of an unintentional injury. From the perspectives of cultivation theory and social learning theory, children’s risk for injury may be influenced by a variety of sources, including media. Previous research suggests that many media sources, including television programs and popular movies, display risky behaviors and a general disregard for safety. The present study added to this literature by quantifying the extent to which a popular form of media, video games, displays injury events and appropriate utilization of safety gear. Research assistants coded trailers of the world’s most popular video games across 13 different genres. Acceptable reliability estimates across assistants were obtained, and results revealed that many video games do not portray safety restraint devices, helmets, or other safety gear. Less than 3% of games show primary characters wearing safety restraint devices while they are driving a vehicle, and helmets are rarely displayed when characters ride bicycles or skateboards. Significant differences in the portrayal of injury events and safety gear usage emerged across Entertainment Software Rating Board ratings. Implications for the video game industry are discussed.
Exemplification 2.0
Authors: Peter Christina , Rossmann Constanze , Keyling Till
Published: March 2014

The Internet in general, and social network sites in particular, provide great potential for communicating health issues. Different forms of online social information, such as user comments and likes, might foster the effectiveness of these communication channels. However, it is unclear whether these types of information affect people’s perceptions and judgments of health issues. Combining exemplification theory with research into online social information, we conducted a 2 × 3 × 2 experiment to address this question. We presented our participants (N = 577) with a discussion of influenza vaccination on mock-up of a Facebook page and varied the direct social information (user comments) and additional indirect social information (comment likes and post likes) given, to assess the impact on individuals’ perceptions of public behavior and risk, and on their personal attitudes and behavioral intentions. Our results showed that the participants relied on direct but not indirect social information when forming judgments.
NK cell recognition of unconventional ligands
Authors: Huntington Nicholas D
Published: March 2014

The March 2014 issue contains a Special Feature on NK cell recognition of unconventional ligands. Natural Killer (NK) cells are bone marrow derived lymphocytes capable of mediating rapid effector responses following pathogen detection in mammals. The name “Natural Killer” derives from the ability of these cells to spontaneously lyse a large range of leukemia cell lines in vitro without prior sensitization. The reviews included in this Special Feature of Immunology and Cell Biology highlight the multifaceted roles of NK cells in detecting unconventional ligands and countering a large range of pathogens and malignancies. Covering a range of topics, including the way adhesion molecules and activating receptors are central to NK cell recognition of their targets, the reviews also highlight some of the challenges that lie ahead in harnessing NK cell function and advancing NK cell immunotherapy strategies to persistent infection, cancer and bone marrow transplantation. Immunology and Cell Biology thanks the coordinator of this Special Feature – Nicholas Huntington – for his planning and input. Further background information on this important topic is available through the accompanying web focus which links to related articles from across Nature Publishing Group.
Size and frequency of natural forest disturbances and the Amazon forest carbon balance
Authors: Espírito-Santo Fernando D.B. , Gloor Manuel , Keller Michael , Malhi Yadvinder , Saatchi Sassan , Nelson Bruce , Junior Raimundo C. Oliveira , Pereira Cleuton , Lloyd Jon , Frolking Steve , Palace Michael , Shimabukuro Yosio E. , Duarte Valdete , Mendoza Abel Monteagudo , López-González Gabriela , Baker Tim R. , Feldpausch Ted R. , Brienen Roel J.W. , Asner Gregory P. , Boyd Doreen S. , Phillips Oliver L.
Published: March 2014

Forest inventory studies in the Amazon indicate a large terrestrial carbon sink. However, field plots may fail to represent forest mortality processes at landscape-scales of tropical forests. Here we characterize the frequency distribution of disturbance events in natural forests from 0.01 ha to 2,651 ha size throughout Amazonia using a novel combination of forest inventory, airborne lidar and satellite remote sensing data. We find that small-scale mortality events are responsible for aboveground biomass losses of ~1.28 Pg C y−1 over the entire Amazon region. We also find that intermediate-scale disturbances account for losses of ~0.01 Pg C y−1, and that the largest-scale disturbances as a result of blow-downs only account for losses of ~0.003 Pg C y−1. Simulation of growth and mortality indicates that even when all carbon losses from intermediate and large-scale disturbances are considered, these are outweighed by the net biomass accumulation by tree growth, supporting the inference of an Amazon carbon sink.
Rheological decoupling at the Moho and implication to Venusian tectonics
Authors: Azuma Shintaro , Katayama Ikuo , Nakakuki Tomoeki
Published: March 2014

Plate tectonics is largely responsible for material and heat circulation in Earth, but for unknown reasons it does not exist on Venus. The strength of planetary materials is a key control on plate tectonics because physical properties, such as temperature, pressure, stress and chemical composition, result in strong rheological layering and convection in planetary interiors. Our deformation experiments show that crustal plagioclase is much weaker than mantle olivine at conditions corresponding to the Moho in Venus. Consequently, this strength contrast may produce a mechanical decoupling between the Venusian crust and interior mantle convection. One-dimensional numerical modeling using our experimental data confirms that this large strength contrast at the Moho impedes the surface motion of the Venusian crust and, as such, is an important factor in explaining the absence of plate tectonics on Venus.
Nanodiamond
Authors:   Royal Society of Chemistry
Published: March 2014

The exceptional mechanical, optical, surface and biocompatibility properties of nanodiamond have gained it much interest. Exhibiting the outstanding bulk properties of diamond at the nanoscale in the form of a film or small particle makes it an inexpensive alternative for many applications.

Nanodiamond is the first comprehensive book on the subject. The book reviews the state of the art of nanodiamond films and particles covering the fundamentals of growth, purification and spectroscopy and some of its diverse applications such as MEMS, drug delivery and biomarkers and biosensing. Specific chapters include the theory of nanodiamond, diamond nucleation, low temperature growth, diamond nanowires, electrochemistry of nanodiamond, nanodiamond flexible implants, and cell labelling with nanodiamond particles.

Edited by a leading expert in nanodiamonds, this is the perfect resource for those new to, and active in, nanodiamond research and those interested in its applications.
Nanodiamond Purification
Authors: Osswald Sebastian
Published: March 2014

Detonation nanodiamond (ND) is one of only a few nanomaterials that can be produced on an industrial scale. Unfortunately, the high content of non-diamond species in the detonation soot (e.g., amorphous and graphitic carbon, metal and metal oxides) prohibits a direct use of the as-produced material in most applications, making the purification one of the most critical steps in ND production. The selection of proper purification conditions requires detailed knowledge of the composition of the powders and the nature of impurities contained within. The development of efficient purification methods, therefore, relies on the availability of suitable characterization methods able to assess and quantify the purity of ND powders. At this point in time, there exists no individual purification step able to remove all impurities present in ND powders. Studies reported in the literature suggest that a combination of acid and air purification currently yields the highest purity levels, while minimizing losses in the diamond phase. Although much progress has been made in the development of efficient and economical purification methods over recent years, several challenges remain. In the short run the most critical step towards widespread utilization of ND is the standardization of the purity assessment. A standardized evaluation of ND purity will then allow for a direct comparison of the effectiveness of existing purification methods in collaboration with process complexity and treatment cost.
Low-temperature Growth of Nanocrystalline Diamond Films in Surface-wave Plasma
Authors: Tsugawa Kazuo , Hasegawa Masataka
Published: March 2014

We have developed a low-temperature growth technique (400 °C or lower) via microwave plasma chemical vapor deposition (CVD) for nanocrystalline diamond (NCD) films using surface-wave plasmas, whereas a substrate temperature of over 400 °C is necessary for conventional diamond CVD. Using this technique, NCD films still grow at a substrate temperature below 100 °C. This enables a wide selection of substrate material, including steel and plastics, to be used. The NCD growth in the surface-wave plasma exhibits a temperature-insensitive growth rate (activation energy =0.07 eV), which indicates a different growth mechanism from that of conventional diamond growth. The analysis of the size distribution of the diamond crystals in the NCD films implies diamond nucleation in the plasma, which is invoked by a low-electron temperature (2–3 eV) of the surface-wave plasma over the growth region. This gas-phase nucleation enables the low-temperature growth of NCD. The NCD film deposited in the surface-wave plasma exhibits high transparency and high tribological performance originating from its small surface roughness and large power-law exponent. The transparency for visible light of NCD films of 500 nm thickness on glass substrates reaches 90%. NCD films deposited on stainless steel substrates exhibit good tribological properties in air at room temperature without any lubrication, particularly a low friction coefficient (<0.1) and a low aggression strength against the stainless steel counterpart (specific wear rate ∼ 109 mm3 mN−1).
P-type and N-type Conductivity in Nanodiamond Films
Authors: Williams Oliver A.
Published: March 2014

Nanodiamond films can exhibit wildly variable carrier transport mechanisms depending on the crystallite size, grain boundary volume fraction, dopant and dopant concentrations. Films constituting larger grain sizes (>30 nm) tend to exhibit higher intrinsic resistivity and follow conventional transport mechanisms, such as band transport, intermediate variable range hopping and metallic conductivity with increasing dopant concentration. At very high doping concentrations and low temperatures they can be superconducting. Smaller grain size films (<30 nm) generally exhibit lower intrinsic resistivity and mostly variable range hopping transport due to a high density of states within the bandgap. These films tend to have higher optical absorption coefficients than those with larger grains sizes.
Superconductivity in Nanostructured Boron-doped Diamond and its Application to Device Fabrication
Authors: Mandal Soumen , Bautze Tobias , Bäuerle Christopher
Published: March 2014

The widely known allotropes of carbon are graphite, diamond and amorphous carbon. Out of these, in its natural form graphite is an electrical conductor, while the other two are insulators. Among the insulating forms, diamond is of particular interest to many professionals because of its exceptional hardness and brilliance. Apart from that, diamond also becomes an interesting material when doped with boron. Above a critical doping concentration doped diamond shows superconductivity with a high critical field. In this chapter we will present our work on nanofabricated boron-doped diamond. We show that diamond is an excellent candidate for making quantum devices, like SQUIDs, which retain its operational properties at magnetic fields as high as 4 T, independent of field direction. We will also present results that demonstrate that this material is also an excellent candidate for making superconducting nanomechanical systems.
All-diamond Electrochemical Devices: Fabrication, Properties, and Applications
Authors: Yang Nianjun , Smirnov Waldemar , Hees Jakob
Published: March 2014

Boron-doped diamond is an ideal material as an electrode for electrochemical and biochemical sensing applications. In this chapter we summarize the fabrication, properties, and applications of all-diamond electrochemical devices. Several devices fabricated in our lab are shown in detail, including all-diamond ultra-microelectrode arrays, nanoelectrode arrays, and atomic force microscope–scanning electrochemical microscope (AFM-SECM) tips.
Charge-transfer-featured materials—promising hosts for fabrication of efficient OLEDs through triplet harvesting via triplet fusion
Authors: Zhou Jie , Chen Ping , Wang Xu , Wang Yan , Wang Yi , Li Feng , Yang Minghui , Huang Yan , Yu Junsheng , Lu Zhiyun
Published: March 2014

An ICT-featured compound with a small ΔEST but a lower lying 3ππ* state than 3CT state is demonstrated to show P-type rather than E-type delay fluorescence, and is a quite promising OLED host.
sp3C–H bond alkylation of ketones with alkenes via ruthenium(ii) catalysed dehydrogenation of alcohols
Authors: Li Bin , Darcel Christophe , Dixneuf Pierre H.
Published: March 2014

The sp3C–H bond alkylation of 2-pyridylethanols upon reaction with alkenes, with a [RuCl2(arene)]2 catalyst and Cu(OAc)2·H2O proceeds via a tandem dehydrogenation/alkylation with alkenes of the resulting ketone.
Preferential site substitution of Eu3+ions in Ca10(PO4)6Cl2nanoparticles obtained using a microwave stimulated wet chemistry technique
Authors: Pazik Robert , Nedelec Jean-Marie , Wiglusz Rafal J.
Published: March 2014

The Eu3+doped Ca10(PO4)6Cl2nanocrystalline powders were synthesized using a microwave stimulated technique. It is demonstrated that for low concentration Ca(ii) (A) site is preferentially substituted whereas increase of Eu3+above 2 mol% results in domination of the Eu3+cations located at Ca(i) (B) site.
Optical methods for sensing and imaging oxygen: materials, spectroscopies and applications
Authors: Wang Xu-dong , Wolfbeis Otto S.
Published: March 2014

Optical probes along with smart polymers and spectroscopies are now widely used to sense oxygenviafiber optics, planar sensors, or nanosensors, often in combination with imaging.
Catalyst-free direct arylsulfonylation of N-arylacrylamides with sulfinic acids: a convenient and efficient route to sulfonated oxindoles
Authors: Wei Wei , Wen Jiangwei , Yang Daoshan , Du Juan , You Jinmao , Wang Hua
Published: March 2014

A catalyst-free procedure has been developed for the construction of sulfonated oxindoles via direct arylsulfonylation of activated alkenes with sulfinic acids.
Hierarchical structures of olefinic blocky copolymer/montmorillonite nanocomposites with collapsed and intercalated clay layers
Authors: Tong Zai-Zai , Zhou Bing , Huang Jie , Xu Jun-Ting , Fan Zhi-Qiang
Published: March 2014

Hierarchical structures of two types of nanocomposite at different scales were characterized by various techniques.
Collaborative Planning Using Universal Design for Learning
Authors: Ralabate Patti Kelly , Currie-Rubin Rachel , Boucher Alyssa , Bartecchi Jennifer
Published: March 2014

Speech language pathologists (SLPs) working in inclusive classrooms bring a different orientation toward developing student goals and delivering language instruction than do general education classroom teachers. It is critical for SLPs and classroom teachers to find cohesive ways of addressing students’ needs while also teaching to high-level state standards. This article discusses Universal Design for Learning, a framework derived from research on neurodiversity and the learning sciences, which accepts learner variability as a strength to be leveraged, not a challenge to be overcome. Further, this article explores the ways in which SLPs can use the Universal Design for Learning framework to leverage their knowledge of student learning needs and language development to work in complementary ways with classroom teachers, set appropriate goals for their students in conjunction with the classroom teacher, and allow both SLPs and classroom teachers to attend to the variability of all their students.
Speech-Language Pathologists and Inclusive Service Delivery: What Are the First Steps?
Authors: Zurawski Lyndsey Pollack
Published: March 2014

Changing service delivery models can be difficult for a variety of reasons. The expanding roles and responsibilities of school-based speech-language pathologists (SLPs) along with the implementation of Common Core State Standards (CCSS) only create more pressure. Implementation of the CCSS does not have to be an anxiety driven task. School-based SLPs can accept the challenge of providing inclusive-based services to meet the diverse needs of the SLPs caseload while providing educationally relevant services.
Adaptive fuzzy decentralised output feedback control of pure‐feedback large‐scale stochastic non‐linear systems with unknown dead zone
Authors: Sui Shuai , Tong Shaocheng , Li Yongming
Published: March 2014

In this study, a robust adaptive fuzzy decentralised backstepping output feedback control approach is proposed for a class of uncertain non‐linear stochastic large‐scale systems in pure‐feedback form. The non‐linear large‐scale systems under study have unknown non‐linear functions, unknown dead‐zone and immeasurable states. Fuzzy logic systems are used to approximate the unknown non‐linear functions, and a K‐filters state observer is designed for estimating the unmeasured states. Based on the information of the bounds of the dead‐zone slopes as well as treating the time‐varying inputs coefficients as a system uncertainty, a robust adaptive fuzzy decentralised output feedback control approach is constructed via the backstepping recursive design technique. It is shown that the proposed control approach can guarantee that all the signals of the resulting closed‐loop system are semi‐globally uniformly ultimately bounded in probability, and the observer errors and the output of the system can be regulated to a small neighbourhood of the origin by choosing design parameters appropriately. A simulation example is provided to show the effectiveness of the proposed approach.
Nonlinear response time-dependent density functional theory combined with the effective fragment potential method
Authors: Zahariev Federico , Gordon Mark S.
Published: March 2014

This work presents an extension of the linear response TDDFT/EFP method to the nonlinear-response regime together with the implementation of nonlinear-response TDDFT/EFP in the quantum-chemistry computer package GAMESS. Included in the new method is the ability to calculate the two-photon absorption cross section and to incorporate solvent effects via the EFP method. The nonlinear-response TDDFT/EFP method is able to make correct qualitative predictions for both gas phase values and aqueous solvent shifts of several important nonlinear properties.
More than the sum of its parts: Coarse-grained peptide-lipid interactions from a simple cross-parametrization
Authors: Bereau Tristan , Wang Zun-Jing , Deserno Markus
Published: March 2014

Interfacial systems are at the core of fascinating phenomena in many disciplines, such as biochemistry, soft-matter physics, and food science. However, the parametrization of accurate, reliable, and consistent coarse-grained (CG) models for systems at interfaces remains a challenging endeavor. In the present work, we explore to what extent two independently developed solvent-free CG models of peptides and lipids—of different mapping schemes, parametrization methods, target functions, and validation criteria—can be combined by only tuning the cross-interactions. Our results show that the cross-parametrization can reproduce a number of structural properties of membrane peptides (for example, tilt and hydrophobic mismatch), in agreement with existing peptide-lipid CG force fields. We find encouraging results for two challenging biophysical problems: (i) membrane pore formation mediated by the cooperative action of several antimicrobial peptides, and (ii) the insertion and folding of the helix-forming peptide WALP23 in the membrane.
Sm(Co1−xNix)5 ordered alloy thin films formed on Cr(100) single-crystal underlayers
Authors: Yanagawa Takato , Hotta Yusuke , Yamada Makoto , Ohtake Mitsuru , Kirino Fumiyoshi , Futamoto Masaaki
Published: March 2014

Sm17(Co1−xNix)83 (at. %, x = 0, 0.2, 0.8, and 1) alloy thin films are deposited on Cr(100) single-crystal underlayers at temperatures ranging between 100 and 500 °C by molecular beam epitaxy. The effects of substrate temperature and Ni/Co composition on the film growth behavior and the detailed resulting structure are investigated. Formation of epitaxial RT5 (R: rare earth metal, T: transition metal) ordered crystals is, respectively, recognized for the films with x of 0, 0.2, 0.8, and 1 deposited at temperatures higher than 400, 400, 300, and 300 °C, whereas the films deposited below the respective temperatures consist of amorphous phases. The order degree increases with increasing the substrate temperature and the Ni content. The order degrees of films with x of 0, 0.2, 0.8, and 1 deposited at 500 °C are 0.6, 0.7, 0.8, and 0.9, respectively. A replacement of Co site in SmCo5 structure with Ni atom is useful for enhancing the formation of RT5 ordered phase.
Frozen density embedding with non-integer subsystems’ particle numbers
Authors: Fabiano Eduardo , Laricchia Savio , Sala Fabio Della
Published: March 2014

We extend the frozen density embedding theory to non-integer subsystems’ particles numbers. Different features of this formulation are discussed, with special concern for approximate embedding calculations. In particular, we highlight the relation between the non-integer particle-number partition scheme and the resulting embedding errors. Finally, we provide a discussion of the implications of the present theory for the derivative discontinuity issue and the calculation of chemical reactivity descriptors.
Intense terahertz emission from intrinsic Josephson junctions by external heat control
Authors: Asai Hidehiro , Kawabata Shiro
Published: March 2014

A practical method for realizing intense terahertz (THz) emission from intrinsic Josephson junctions (IJJs) by utilizing external local-heating is proposed and demonstrated theoretically. An artificial temperature distribution induced by local heating strongly excites Josephson plasma waves inside IJJs. Accordingly, the emission power of the THz wave is enhanced drastically, and it can reach the order of mW. Our result indicates that the use of local heat control is a powerful method to realize practical solid-state THz-emitters based on IJJs.
Unraveling chaotic attractors by complex networks and measurements of stock market complexity
Authors: Cao Hongduo , Li Ying
Published: March 2014

We present a novel method for measuring the complexity of a time series by unraveling a chaotic attractor modeled on complex networks. The complexity index R, which can potentially be exploited for prediction, has a similar meaning to the Kolmogorov complexity (calculated from the Lempel–Ziv complexity), and is an appropriate measure of a series' complexity. The proposed method is used to research the complexity of the world's major capital markets. None of these markets are completely random, and they have different degrees of complexity, both over the entire length of their time series and at a level of detail. However, developing markets differ significantly from mature markets. Specifically, the complexity of mature stock markets is stronger and more stable over time, whereas developing markets exhibit relatively low and unstable complexity over certain time periods, implying a stronger long-term price memory process.
Scaling of chaos in strongly nonlinear lattices
Authors: Mulansky Mario
Published: March 2014

Although it is now understood that chaos in complex classical systems is the foundation of thermodynamic behavior, the detailed relations between the microscopic properties of the chaotic dynamics and the macroscopic thermodynamic observations still remain mostly in the dark. In this work, we numerically analyze the probability of chaos in strongly nonlinear Hamiltonian systems and find different scaling properties depending on the nonlinear structure of the model. We argue that these different scaling laws of chaos have definite consequences for the macroscopic diffusive behavior, as chaos is the microscopic mechanism of diffusion. This is compared with previous results on chaotic diffusion [M. Mulansky and A. Pikovsky, New J. Phys. 15, 053015 (2013)], and a relation between microscopic chaos and macroscopic diffusion is established.
Polymorphic structure evolution and large piezoelectric response of lead-free (Ba,Ca)(Zr,Ti)O3 ceramics
Authors: Tian Ye , Chao Xiaolian , Jin Li , Wei Lingling , Liang Pengfei , Yang Zupei
Published: March 2014

The polymorphic structure evolution of (Ba,Ca)(Zr,Ti)O3 piezoelectric ceramics was investigated by analysis of the in situ X-ray diffraction and dielectric spectra. The results indicated that a confined orthorhombic (O) phase region induced by the approach of the rhombohedral (R) and tetragonal (T) phases existed in an extremely narrow temperature range of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 composition. The electric properties near the O–T phase boundaries of (Ba0.95Ca0.05)(Zr0.05Ti0.95)O3 and (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 were compared. The results suggested that the confined O phase region is an important factor that contributes to the extremely large piezoelectric response.
Understanding the impact of Tc and Hk variation on signal-to-noise ratio in heat-assisted magnetic recording
Authors: Li Hai , Zhu Jian-Gang
Published: March 2014

In this work, we present a micromagnetic study on the signal-to-noise ratio (SNR) impacts of Curie temperature, Tc, variation and anisotropy field, Hk, variation in FePt media for heat assisted magnetic recording. Results show that the SNR is much more sensitive to Tc variation than to Hk variation. The study shows the two causes yield different noise characteristics. The nature of the noise due to Tc variation is dominated by transition jitter whereas Hk variation increases erasure-after-write, resulting in both transition jitter and amplitude variation.
Temperature dependence of refractive indices for 4H- and 6H-SiC
Authors: Xu Chunhua , Wang Shunchong , Wang Gang , Liang Jingkui , Wang Shanpeng , Bai Lei , Yang Junwei , Chen Xiaolong
Published: March 2014

The refractive indices of 4H- and 6H-SiC single crystals at wavelengths of 404.7, 435.8, 480.0, 546.1, 587.5, 643.8, 706.5, 852.1, 1014.0, 1529.6, and 2325.4 nm are carefully measured from 293 to 493 K by the method of minimum deviation. We find that ordinary (no) and extraordinary (ne) refractive indices for both crystals increase with the elevated temperature. The temperature-dependent Sellmeier equations of refractive indices for 4H- and 6H-SiC are obtained and then thermo-optic coefficients (TOCs) are derived. The TOCs diminish very quickly at visible light region and become less dependent in the infrared light region. Such changing trends of TOCs can be explained by single-oscillator approximation. The results may provide the important reference value for designing the optoelectronic and nonlinear optical devices based on SiC.
Calculating field emission current in nanodiodes—A multi-group formalism with space charge and exchange-correlation effects
Authors: Biswas Debabrata , Kumar Raghwendra
Published: March 2014

Inclusion of electron-electron interaction is essential in nano-diodes to understand the underlying physical phenomenon and tailor devices accordingly. However, both space charge and exchange-correlation interaction involve electrons at different energies and hence a self-consistent multi-energy-group solution of the Schrödinger-Poisson system is required. It is shown here that the existence of a limiting density-dependent potential at low applied voltages allows calculation of the field emission current. Despite additional interactions, a Fowler-Nordheim behaviour is observed. It is also found that the exchange-correlation potential dominates at these voltages in nanogaps and possibly leads to a higher turn-on voltage.
A new Bi0.5Na0.5TiO3 based lead-free piezoelectric system with calculated end-member Bi(Zn0.5Hf0.5)O3
Authors: Liu Feng , Wahyudi Olivia , Li Yongxiang
Published: March 2014

The phase structure, dielectric and piezoelectric properties of a new lead-free piezoelectric system (1 − x)Bi0.5Na0.5TiO3–xBi(Zn0.5Hf0.5)O3 [(1 − x)BNT–xBZH, x = 0, 0.01, 0.02, 0.03, and 0.04] were investigated. The structure of Bi(Zn0.5Hf0.5)O3 was calculated using first-principles method and (1 − x)BNT–xBZH ceramics were fabricated by conventional solid-state process. At room temperature, a morphotropic phase boundary (MPB) from rhombohedral to pseudocubic is identified near x = 0.02 by the analysis of X-ray diffraction patterns. The ceramics with MPB near room temperature exhibit excellent electrical properties: the Curie temperature, maximum polarization, remnant polarization, and coercive field are 340 °C, 56.3 μC/cm2, 43.5 μC/cm2, and 5.4 kV/mm, respectively, while the maximum positive bipolar strain and piezoelectric coefficient are 0.09% and 92 pC/N, respectively. In addition, a linear relationship between the MPB phase boundary composition and the calculated tetragonality of non-BNT end-member was demonstrated. Thus, this study not only shows a new BNT-based lead-free piezoelectric system but also suggest a new way to predict the composition at MPB a priori when designing new lead-free piezoelectric system.
Analysis of permeability for transient two-phase flow in fractal porous media
Authors: Tan Xiao-Hua , Li Xiao-Ping , Liu Jian-Yi , Zhang Guang-Dong , Zhang Lie-Hui
Published: March 2014

A relative permeability model for transient two-phase flow in fractal porous media is derived based on the fractal characteristics of pore size distribution and the assumption that porous media consists of capillary bundles. The functions in this model are tortuosity fractal dimension, pore fractal dimension, and maximum and minimum pore diameters. Every parameter has clear physical meaning without the use of empirical constants. Good agreement between model predictions and experimental data is obtained, the sensitive parameters that influence the relative permeability are specified and their effects on relative permeability are discussed.
Spin and charge thermopower of resonant tunneling diodes
Authors: Nicolau Javier H. , Sánchez David
Published: March 2014

We investigate thermoelectric effects in quantum well systems. Using the scattering approach for coherent conductors, we calculate the thermocurrent and thermopower both in the spin-degenerate case and in the presence of giant Zeeman splitting due to magnetic interactions in the quantum well. We find that the thermoelectric current at linear response is maximal when the well level is aligned with the Fermi energy and is robust against thermal variations. Furthermore, our results show a spin voltage generation in response to the applied thermal bias, giving rise to large spin Seebeck effects tunable with external magnetic fields, quantum well tailoring, and background temperature.
On the limits to Ti incorporation into Si using pulsed laser melting
Authors: Mathews Jay , Akey Austin J. , Recht Daniel , Malladi Girish , Efstathiadis Harry , Aziz Michael J. , Warrender Jeffrey M.
Published: March 2014

Fabrication of p-Si(111) layers with Ti levels well above the solid solubility limit was achieved via ion implantation of 15 keV 48Ti+ at doses of 1012 to 1016 cm−2 followed by pulsed laser melting using a Nd:YAG laser (FWHM = 6 ns) operating at 355 nm. All implanted layers were examined using cross-sectional transmission electron microscopy, and only the 1016 cm−2 Ti implant dose showed evidence of Ti clustering in a microstructure with a pattern of Ti-rich zones. The liquid phase diffusivity and diffusive velocity of Ti in Si were estimated to be 9 × 10−4 cm2/s and (2 ± 0.5) × 104 m/s, respectively. Using these results the morphological stability limit for planar resolidification of Si:Ti was evaluated, and the results indicate that attaining sufficient concentrations of Ti in Si to reach the nominal Mott transition in morphologically stable plane-front solidification should occur only for velocities so high as to exceed the speed limits for crystalline regrowth in Si(111).
Spaser based on Fano resonance in a rod and concentric square ring-disk nanostructure
Authors: Huo Y. Y. , Jia T. Q. , Zhang Y. , Zhao H. , Zhang S. A. , Feng D. H. , Sun Z. R.
Published: March 2014

This paper reports a spaser based on Fano resonance of a plasmonic nanostructure consisting of a rod and concentric square ring-disk structure coated with a layer of gain media. The amplification of the dark quadrupolar mode at the Fano resonance wavelength causes the spaser with a high Purcell factor of 3.24 × 107, a high signal to noise ratio of 4.4 × 106, and a lower threshold of 0.02086. These significant optical properties are attributed to the greatly enhanced spontaneous emission and depressed radiation loss supported by the strong localized dark mode at the Fano resonance wavelength.
Dependence of the flux-creep activation energy on current density and magnetic field for a Ca10(Pt3As8)[(Fe1−xPtx)2As2]5 single crystal
Authors: Ge J. , Gutierrez J. , Li J. , Yuan J. , Wang H.-B. , Yamaura K. , Takayama-Muromachi E. , Moshchalkov V. V.
Published: March 2014

We have performed detailed ac susceptibility measurements to investigate the vortex dynamics in a Ca10(Pt3As8)[(Fe1−xPtx)2As2]5 single crystal as a function of temperature, frequency, ac amplitude, and dc field. The field dependence of the activation energy U is derived in the framework of thermally activated flux creep theory, yielding a power law dependence of U ∼ Hα with α≈ −1.0 for H above 0.30 T, while below 0.3 T U is independent of the field. The activation energy reaches 104 K at low fields, suggesting strong pinning in the material. The nonlinear function of the activation energy vs. the current density is determined, which shows logarithmic dependence U(J)∝lnJ.
A spin light emitting diode incorporating ability of electrical helicity switching
Authors: Nishizawa N. , Nishibayashi K. , Munekata H.
Published: March 2014

Fabrication and optical characteristics of a spin light-emitting-diode (spin-LED) having dual spin-injection electrodes with anti-parallel magnetization configuration are reported. Alternating a current between the two electrodes using a computer-driven current source has led us to the observation of helicity switching of circular polarization at the frequency of 1 kHz. Neither external magnetic fields nor optical delay modulators were used. Sending dc-currents to both electrodes with appropriate ratio has resulted in continuous variation of circular polarization between the two opposite helicity, including the null polarization. These results suggest that the tested spin-LED has the feasibility of a monolithic light source whose circular polarization can be switched or continuously tuned all electrically.
Magnonic band gaps in two-dimension magnonic crystals with diffuse interfaces
Authors: Wang Qi , Zhang Huaiwu , Ma Guokun , Tang Xiaoli , Liao Yulong , Zhong Zhiyong
Published: March 2014

In this paper, the plane wave method is extended to include the diffuse interface in the calculation of the dispersion of spin waves in two-dimension magnonic crystals. The diffuse interfaces with linear and sinusoidal profiles of variation in the spontaneous magnetization and exchange constant are considered and the effects of the thicknesses and profiles of diffuse interfaces on the magnonic band gaps are investigated. The results show that the thicknesses and profiles of diffuse interfaces are clearly seen to play a significant role in determining the size and position of the magnonic band gaps in the both square and triangular lattices in the exchange interaction regime. The smooth (linear or sinusoidal) interface does not lead to disappearance of the band gaps, instead it may lead to larger band gaps than those in the model with sharp (infinitely thin) diffuse interface under certain conditions.
Photo-modulated thin film transistor based on dynamic charge transfer within quantum-dots-InGaZnO interface
Authors: Liu Xiang , Yang Xiaoxia , Liu Mingju , Tao Zhi , Dai Qing , Wei Lei , Li Chi , Zhang Xiaobing , Wang Baoping , Nathan Arokia
Published: March 2014

The temporal development of next-generation photo-induced transistor across semiconductor quantum dots and Zn-related oxide thin film is reported in this paper. Through the dynamic charge transfer in the interface between these two key components, the responsibility of photocurrent can be amplified for scales of times (∼104 A/W 450 nm) by the electron injection from excited quantum dots to InGaZnO thin film. And this photo-transistor has a broader waveband (from ultraviolet to visible light) optical sensitivity compared with other Zn-related oxide photoelectric device. Moreover, persistent photoconductivity effect can be diminished in visible waveband which lead to a significant improvement in the device's relaxation time from visible illuminated to dark state due to the ultrafast quenching of quantum dots. With other inherent properties such as integrated circuit compatible, low off-state current and high external quantum efficiency resolution, it has a great potential in the photoelectric device application, such as photodetector, phototransistor, and sensor array.
Spin-lattice dynamics simulation of external field effect on magnetic order of ferromagnetic iron
Authors: Chui C. P. , Zhou Yan
Published: March 2014

Modeling of field-induced magnetization in ferromagnetic materials has been an active topic in the last dozen years, yet a dynamic treatment of distance-dependent exchange integral has been lacking. In view of that, we employ spin-lattice dynamics (SLD) simulations to study the external field effect on magnetic order of ferromagnetic iron. Our results show that an external field can increase the inflection point of the temperature. Also the model provides a better description of the effect of spin correlation in response to an external field than the mean-field theory. An external field has a more prominent effect on the long range magnetic order than on the short range counterpart. Furthermore, an external field allows the magnon dispersion curves and the uniform precession modes to exhibit magnetic order variation from their temperature dependence.
Crystal structure and physical properties of Mo2B: First-principle calculations
Authors: Zhou Dan , Wang Jingshu , Cui Qiliang , Li Quan
Published: March 2014

Several decades ago, Mo2B was assumed to have an Al2Cu-type structure with I4/mcm space group. Using ab initio phonon calculations, we identify the earlier proposed Al2Cu-type structure is dynamically unstable at ambient pressure. An energetically more favorable phase with the tetragonal I4/m structure was then predicted by employing frozen-phonon technique. The currently predicted I4/m phase is mechanically and dynamically stable and energetically more favorable than that of the earlier proposed Al2Cu-type structure. The electronic structures calculations indicate that Mo2B is a metal with several bands crossing the Fermi level. Our analysis indicates that the three-dimensional network of the covalent Mo-B bond is responsible for the ultra-incompressible property of Mo2B.
How biological vision succeeds in the physical world
Authors: Purves Dale , Monson Brian B. , Sundararajan Janani , Wojtach William T.
Published: March 2014

Biological visual systems cannot measure the properties that define the physical world. Nonetheless, visually guided behaviors of humans and other animals are routinely successful. The purpose of this article is to consider how this feat is accomplished. Most concepts of vision propose, explicitly or implicitly, that visual behavior depends on recovering the sources of stimulus features either directly or by a process of statistical inference. Here we argue that, given the inability of the visual system to access the properties of the world, these conceptual frameworks cannot account for the behavioral success of biological vision. The alternative we present is that the visual system links the frequency of occurrence of biologically determined stimuli to useful perceptual and behavioral responses without recovering real-world properties. The evidence for this interpretation of vision is that the frequency of occurrence of stimulus patterns predicts many basic aspects of what we actually see. This strategy provides a different way of conceiving the relationship between objective reality and subjective experience, and offers a way to understand the operating principles of visual circuitry without invoking feature detection, representation, or probabilistic inference.