ALBERT

Beschreibung: We estimate the contamination risks from the atmospheric dispersion of radionuclides released by severe nuclear power plant accidents using the ECHAM/Modular Earth Submodel System (MESSy) atmospheric chemistry (EMAC) atmospheric chemistry-general circulation model at high resolution (50 km). We present an overview of global risks and also a case study of nuclear power plants that are currently under construction, planned and proposed in the Eastern Mediterranean and Middle East, a region prone to earthquakes. We implemented continuous emissions from each location, making the simplifying assumption that all potential accidents release the same amount of radioactivity. We simulated atmospheric transport and decay, focusing on 137Cs and 131I as proxies for particulate and gaseous radionuclides, respectively. We present risk maps for potential surface layer concentrations, deposition and doses to humans from the inhalation exposure of 131I. The estimated risks exhibit seasonal variability, with the highest surface level concentrations of gaseous radionuclides in the Northern Hemisphere during winter.

Beschreibung: The long-lived pioneer species Pericopsis elata is one of the rare tropical timbers on the list of the Convention on International Trade of Endangered Species, supporting the need for accurate and reliable growth data. In one planted and one natural forest in the Democratic Republic of Congo, respectively four and 37 Pericopsis stem disks were collected. The tree-ring series of planted trees were used to confirm annual tree-ring formation. For the natural forest, a tree-ring chronology with 24 stem disks ranged from 1852 up to 2008. This chronology was compared with time-series of local precipitation, resulting in a significant correlation with the second half of the rainy season (September–November). This seasonal precipitation was related with sea surface temperatures of the West Indian Ocean. Higher precipitation during El Niño years corresponded with higher tree-ring indices but differences were not significant. In addition, pointer years were rare and did not have a consistent link with extreme climatic conditions. The existence of annual tree rings encourages further tree-ring analyses of P. elata and other flagship timber species in order to further document climate-growth responses and to provide the long-term framework that is needed for sustainable management planning.

Beschreibung: Publication date: 2014 Source: Procedia Environmental Sciences, Volume 22 Author(s): Herman van Os , Rien Herber , Bert Scholtens The decision-making process for subsurface activities in the Netherlands has been unable to cope with the driving forces related to social acceptance in several recently proposed subsurface activities. We therefore investigated the possibility to include the triangle of social acceptance in the decision-making process. Our conceptual model relates the stakeholders, their goals and the driving forces to each other. We developed a framework, which describes the interaction between eleven design criteria for a Decision Support System (DSS). This framework will enable us to design a better, from a social acceptance perspective, DSS for subsurface activities in the Netherlands. Since the goals addressed in the decision-making process are very broad and the stakeholders are quite diverse, a single uniform DSS is not able to provide a satisfactory solution. We therefore suggest to design a DSS that is matched with each class of social acceptance.

Beschreibung: Publication date: 2014 Source: Procedia Environmental Sciences, Volume 22 Author(s): Yoshie Inada , Shinobu Izumi , Motoya Koga , Shigehito Matsubara We are developing a planning support system for welfare urban design. If we quantify the optimal route (the route that is the easiest to pass through) for challenged people, we will be able to select the areas that require adjustment in terms of accessibility with greater efficiency. In this paper we report on our development of the prototype system to present an optimal route for wheelchair users, and also, the two workshops we had for evaluating the accuracy of the resulted optimal route.

Beschreibung: Publication date: 2014 Source: Procedia Environmental Sciences, Volume 22 Author(s): Erfaneh Allameh , Mohammadali Heidari , Bauke De Vries , Harry Timmermans , Mohammad Masoud , Farhang Mozaffar Almost everyone would agree that teleworking is increasingly growing; but beyond this broad statement, we know little about how people behave when they work at home and how they balance their work and life. User comfort and productivity cannot be addressed properly, without a deep understanding of usersʼ working behavior. This gap is even deeper when it comes to the domain of smart homes as new types of housing which aim to enhance working at home. Hence, more user-centered studies are needed to comprehend the interrelationships among housing, technology, daily life and the work activities. In this paper, we use the outputs of an experiment to model usersʼ work activities in a smart home. The experiment was conducted among 254 respondents, who were asked to explore a smart home in a virtual environment and then to arrange their daily activities including work related activities in the virtual smart home. A choice modeling approach, based on the Multinomial Logit Model (MNL), is applied to model how an individual works at a smart home given influential factors such as the individualsʼ socio-demographic profile and their current lifestyle. Two features of working in a smart home are covered in this paper, namely, “the integration of work activities with other daily activities” and “the location of work activities in the house”. The results give better insight into the future trends of working at home and the effects of smart homes on working behavior of people. The results can be used in further developments of both smart homes and teleworking.

Beschreibung: Publication date: 2014 Source: Procedia Environmental Sciences, Volume 22 Author(s): Jinhee Kim , Soora Rasouli , Harry Timmermans Hybrid choice models have been developed as an extension of discrete choice models, particularly multinomial logit models, in an attempt to include attitudinal variables. The quintessence of hybrid choice models is that a model of attitude formation is estimated and the estimated attitudes are added to the commonly used set of attributes in discrete choice models: attributes of the choice alternatives and socio-demographic variables. The most commonly applied model is based on linear specifications, both for the attitude model and the utility function. In this review paper, we discuss the principles underlying the hybrid choice model, summarize the specifications used in previous applications of the model and then continue discussing recent progress that added social influence to the model specification and replaced the linear specification of the utility function with a nonlinear function.

Beschreibung: Publication date: 2014 Source: Procedia Environmental Sciences, Volume 22 Author(s): Yountaik Leem , Sang Ho Lee , Jungho Yoon To overcome many difficulties in sustaining the satisfying quality of life for a large population 1 , urban spaces are evolving toward more efficient spaces by combination with ICTs (information and communication technologies) and raising the possibility to provide improved urban services which can enrich the quality of life of the citizen. In many cities over the world, a good number of public and private services in transportation, environment, urban safety from crime or disaster, health and other fields are designed and implemented with IT infrastructure. In spite of the expectation of cost-effective urban services based on the linkage between data and systems, obstructions in administrative and technical domains have made it difficult to be implemented. In this study, two advanced ICTs based urban services, which were developed by linkage and convergence of urban information and systems of Korea were introduced and analysed. The structural design of system convergence and data sharing scheme of Carbon Emission Monitoring System (CEMS) in Sejong City uses UIS (Urban Information System for local authorities), GIS data and other data provided by the public agencies, such as Korea Meteorological Administration for the monitoring and analysing the characteristics of the energy consumption of household 2 . Another system, Urban Integrated CCTV Control System (ICCS) in Anyang City, shows integrated CCTV networks for crime prevention, traffic control and public facility management to provide extended urban services, such as disaster prevention, police investigation and others. Qualitative and Quantitative effects analyses with technical and policy directions were suggested for the development and improvement of future urban services for a liveable city.

Beschreibung: Background: Bacterial wilt caused by Ralstonia solanacearum is a serious soil-borne disease of peanut (Arachis hypogaea L). The molecular basis of peanut response to R. solanacearum remains unknown. To understand the resistance mechanism behind peanut resistance to R. solanacearum, we used RNA-Seq to perform global transcriptome profiling on the roots of peanut resistant (R) and susceptible (S) genotypes under R. solanacearum infection. Results: A total of 4.95 x 108 raw sequence reads were generated and subsequently assembled into 271, 790 unigenes with an average length of 890 bp and a N50 of 1, 665 bp. 179, 641 unigenes could be annotated by public protein databases. The pairwise transcriptome comparsions of time course (6, 12, 24, 48 and 72 h post inoculation) were conducted 1) between inoculated and control samples of each genotype, 2) between inoculated samples of R and S genotypes. The linear dynamics of transcriptome profile was observed between adjacent samples for each genotype, two genotypes shared similar transcriptome pattern at early time points with most significant up regulation at 12 hour, and samples from R genotype at 24 h and S genotype at 48 h showed similar transcriptome pattern, significant differences of transcriptional profile were observed in pairwise comparisons between R and S genotypes. KEGG analysis showed that the primary metabolisms were inhibited in both genotypes and stronger inhibition in R genotype post inoculation. The defense related genes (R gene, LRR-RLK,cell wall genes, etc.) generally showed a genotype-specific down regulation and different expression between both genotypes. Conclusion: This transcriptome profiling provided the largest data set that explores the dynamic in crosstalk between peanut and R. solanacearum. The results suggested that the down-regulation of primary metabolism is contributed to the resistance difference between R and S genotypes. The genotype-specific expression pattern of defense related DEGs also contributed to the resistance difference between R and S genotype. This study will strongly contribute to better understand the molecular interaction between plant and R. solanacearum.

Beschreibung: Our aim is to explore general practitioners’ (GPs’) knowledge about EMF, and to assess whether different knowledge structures are related to the GPs’ concern about EMF. Random samples were drawn from lists of GPs in Germany in 2008. Knowledge about EMF was assessed by seven items. A latent class analysis was conducted to identify latent structures in GPs’ knowledge. Further, the GPs’ concern about EMF health risk was measured using a score comprising six items. The association between GPs’ concern about EMF and their knowledge was analysed using multiple linear regression. In total 435 (response rate 23.3%) GPs participated in the study. Four groups were identified by the latent class analysis: 43.1% of the GPs gave mainly correct answers; 23.7% of the GPs answered low frequency EMF questions correctly; 19.2% answered only the questions relating EMF with health risks, and 14.0% answered mostly “don’t know”. There was no association between GPs’ latent knowledge classes or between the number of correct answers given by the GPs and their EMF concern, whereas the number of incorrect answers was associated with EMF concern. Greater EMF concern in subjects with more incorrect answers suggests paying particular attention to misconceptions regarding EMF in risk communication.

Beschreibung: This study aims to explore the efficiency of using online education as an intervention measure to prevent occupational hazards in a clinical nursing setting. The subjects were 320 female nursing staff from two hospitals in Taiwan. The questionnaire results indicated that the subjects primarily experienced human factor occupational hazards, as well as psychological and social hazards. Specifically, 73.1% and 69.8% of the subjects suffered from poor sleep quality and low back pain, respectively. After web-based learning, the experimental group had higher post-test scores than the control group in terms of knowledge, attitudes, and practices (KAP). However, there was only a significant difference (p 〈 0.05) in their knowledge about the prevention of occupational hazards. It is suggested that an online discussion may enhance nursing staff’s participation in web-based learning, and further facilitate their comments on negative factors. The findings can highly promote nursing staff’s attitudes and practices toward preventing occupational hazards through web-based learning.

Beschreibung: Ambient particulate matters and temperature were reported to have additive effects over the respiratory disease hospital admissions and deaths. The purpose of this study is to discuss the interactive pulmonary toxicities of cold stress and fine particulate matter (PM2.5) exposure by estimating inflammation and oxidative stress responses. 48 Wistar male rats, matched by weight and age, were randomly assigned to six groups, which were treated with cold stress alone (0 °C, 10 °C, and 20 °C (Normal control)) and cold stresses plus PM2.5 exposures respectively. Cold stress alone groups were intratracheal instillation of 0.25 mL normal saline, while cold stress plus PM2.5 exposure groups were intratracheal instillation of 8 mg/0.25 mL PM2.5. These procedures were carried out for three times with an interval of 48 hours for each treatment. All rats were sacrificed after 48 hours of the third treatment. The bronchoalveolar lavage fluid (BALF) was collected for analyzing inflammatory cells and cytokines, and lung homogenate MDA was determined for oxidative stress estimation. Results showed higher level of total cell and neutrophil in the BALF of PM2.5 exposed groups (p 〈 0.05). Negative relationships between cold stress intensity and the level of tumor necrosis factor alpha (TNF-a), C-reactive protein (CRP) interleukin-6 (IL-6) and interleukin-8 (IL-8) in BALF were indicated in PM2.5 exposure groups. Exposure to cold stress alone caused significant increase of inflammatory cytokines and methane dicarboxylic aldehyde (MDA) and decline of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity only in 0 °C exposure group (p 〈 0.05). The two-way ANOVA found significant interactive effects between PM2.5 exposure and cold stress in the level of neutrophil, IL-6 and IL-8 and SOD activity (p 〈 0.05). These data demonstrated that inflammation and oxidative stress involved in the additive effect of PM2.5 exposure and cold stress on pulmonary toxicity, providing explanation for epidemiological studies on the health effect of ambient PM2.5 and cold stress.

Beschreibung: This paper presents a detailed description of an approach designed to investigate the application of the Health Impact Assessment (HIA) framework to assess the potential health impacts of climate change. A HIA framework has been combined with key climate change terminology and concepts. The fundamental premise of this framework is an understanding of the interactions between people, the environment and climate. The diversity and complexity of these interactions can hinder much needed action on the critical health issue of climate change. The objectives of the framework are to improve the methodology for understanding and assessing the risks associated with potential health impacts of climate change, and to provide decision-makers with information that can facilitate the development of effective adaptation plans. While the process presented here provides guidance with respect to this task it is not intended to be prescriptive. As such, aspects of the process can be amended to suit the scope and available resources of each project. A series of working tables has been developed to assist in the collation of evidence throughout the process. The framework has been tested in a number of locations including Western Australia, Solomon Islands, Vanuatu and Nauru.

Beschreibung: Publication date: Available online 12 November 2014 Source: Geoscience Frontiers Author(s): Wengang Zhang , Anthony T.C. Goh Piles are long, slender structural elements used to transfer the loads from the superstructure through weak strata onto stiffer soils or rocks. For driven piles, the impact of the piling hammer induces compression and tension stresses in the piles. Hence, an important design consideration is to check that the strength of the pile is sufficient to resist the stresses caused by the impact of the pile hammer. Due to its complexity, pile drivability lacks a precise analytical solution with regard to the phenomena involved. In situations where measured data or numerical hypothetical results are available, neural networks stand out in mapping the nonlinear interactions and relationships between the system's predictors and dependent responses. In addition, unlike most computational tools, no mathematical relationship assumption between the dependent and independent variables has to be made. Nevertheless, neural networks have been criticized for their long trial-and-error training process since the optimal configuration is not known a priori. This paper investigates the use of a fairly simple nonparametric regression algorithm known as multivariate adaptive regression splines (MARS), as an alternative to neural networks, to approximate the relationship between the inputs and dependent response, and to mathematically interpret the relationship between the various parameters. In this paper, the Back propagation neural network (BPNN) and MARS models are developed for assessing pile drivability in relation to the prediction of the Maximum compressive stresses (MCS), Maximum tensile stresses (MTS), and Blow per foot (BPF). A database of more than four thousand piles is utilized for model development and comparative performance between BPNN and MARS predictions. Graphical abstract

Beschreibung: Governments, tech giants and individuals must act together if we are to clamp down on threats and abuse in the digital world

Beschreibung: From body invasion Alien -style to hallucinogenic poisons and limpet mines, fungi have astonishingly creative ways of dispatching their foes

Beschreibung: Publication date: Available online 18 November 2014 Source: Geoscience Frontiers Author(s): Fei Gao , Lily Wang , Mudan Yin

Beschreibung: Publication date: Available online 20 November 2014 Source: Geoscience Frontiers Author(s): I.V. Ashchepkov , A.M. Logvinova , T. Ntaflos , L.F. Reimers , Z.V. Spetsius , N.V. Vladykin , D.S. Yudin , A.V. Travin , H. Downes , V.S. Palesskiy Heavy mineral concentrate and xenoliths from late autolithic breccia and porphyritic kimberlite of the Sytykanskaya pipe (Alakit field, Yakutia, Russia) were studied by EPMA and LA-ICPMS methods to obtain PTXfO 2 diagrams. Trends in P- Fe# - CaO - fO 2 for minerals from the porphyritic kimberlite show greater discontinuities than xenocrysts from the breccia. Xenoliths show the widest variation at all pressures. Protokimberlite systems are marked by ilmenite PT points that range from the lithosphere base (7.5 GPa) to a pyroxenite lens situated at intermediate depths (5 - 3.5 GPa) with increasing Cr because of AFC that formed two metasomatic groups with differing Fe#Ol (∼ 10-12 and 13-15). The first Opx-Gar-based mantle geotherm for the Alakit field based on 10 mineral associations is close to the 35 mW/m 2 geotherm at 6.5 GPa and 600 ° C, i.e. near to the Moho. The oxidation state for the megacrystalline ilmenites in the lithosphere base is higher than for other kimberlites in Yakutia. Calculated parental melts for clinopyroxene and garnet by xenocrysts from the breccia show highly inclined linear REE patterns with deep HFSE troughs similar to differentiated protokimberlite magmas. Melts calculated for metasomatic xenoliths have less inclined slopes without troughs in spider diagrams. Garnets reveal S-shaped REE patterns. Calculated melts for garnets from graphite-bearing Cr-websterites located mainly in middle part of the mantle column show slightly inclined convex REE patterns and Ba-Sr troughs with variable enrichment in Nb-Ta-U. The calculated parental melts for clinopyroxenes have inclined REE spectra with a depression in HFSE. Metasomatic clinopyroxenes have enriched patterns with Ba, Zr peaks. 40 Ar- 39 Ar analyses of dispersed phlogopites from the Alakit mantle xenoliths yield a Proterozoic (1154 Ma) age, corresponding to continental arc metasomatism. Alkaline and Ti-rich veins with alkali amphiboles close to richterite formed at ∼1015 Ma and mark a plume event in Rodinia mantle. The∼600-550 Ma stage relates to Rodinia break-up. The last metasomatic event near 385 Ma is related to the protokimberlite. Graphical abstract

Beschreibung: Charge generation in a typical intermediate connector, composed of “n-type doped layer/transition metal oxide (TMO)/hole transporting layer (HTL),” of a tandem organic light-emitting device (OLED) has recently been found to arise from charge transfer at the TMO/HTL interfaces. In this paper, we investigate the effect of hole injection barriers from intermediate connectors on the performance of tandem OLEDs. The hole injection barriers are caused by the offset of the highest occupied molecular orbital (HOMO) energy levels between HTLs contained in the intermediate connector and the top electroluminescence (EL) unit. We also find that although charge generation can occur at the interfaces between the TMO and a wide variety of HTLs of different HOMO values, an increase in the hole injection barrier however limits the electroluminescence efficiency of the top EL units. In the case of large hole injection barriers, significant charge accumulation in the HTLs makes the intermediate connector lose its functionality gradually over operating time, and limits device stability.

Beschreibung: Author(s): N. A. Sinitsyn We consider nonadiabatic transitions in explicitly time-dependent systems with Hamiltonians of the form Ĥ(t)=Â+B̂t+Ĉ/t, where t is time and Â, B̂, Ĉ are Hermitian N×N matrices. We show that in any model of this type, scattering matrix elements satisfy nontrivial exact constraints that follow fr... [Phys. Rev. A 90, 062509] Published Thu Dec 11, 2014

Beschreibung: Author(s): P. Szańkowski, M. Trippenbach, and J. Chwedeńczuk We demonstrate that memory in an N-qubit system subjected to decoherence, is a potential resource for the slowdown of the entanglement decay. We show that this effect can be used to retain the sub-shot-noise sensitivity of the parameter estimation in quantum interferometry. We calculate quantum Fish... [Phys. Rev. A 90, 063619] Published Thu Dec 11, 2014

Beschreibung: Author(s): J. Lam, C. J. Rennick, and T. P. Softley Near-threshold photodissociation of Br 2 from a supersonic beam produces slow bromine atoms that are trapped in the magnetic-field minimum formed between two opposing permanent magnets. Here we quantify the dominant trap-loss rate due to collisions with two sources of residual gas: the background lim... [Phys. Rev. A 90, 063419] Published Thu Dec 11, 2014

Beschreibung: Author(s): Y. Lutsyshyn, G. E. Astrakharchik, C. Cazorla, and J. Boronat We study the zero-temperature quantum phase transition between liquid and hcp solid 4 He. We use the variational method with a simple yet exchange-symmetric and fully explicit wave function. It is found that the optimized wave function undergoes spontaneous symmetry breaking and describes the quantum... [Phys. Rev. B 90, 214512] Published Thu Dec 11, 2014

Beschreibung: Author(s): L. Z. Deng, B. Lv, Z. Wu, Y. Y. Xue, W. H. Zhang, F. S. Li, L. L. Wang, X. C. Ma, Q. K. Xue, and C. W. Chu We report a detailed investigation on the superconductivity in eight 1–4 unit-cell (UC) FeSe films on SrTiO 3 substrates by measuring their magnetization and sheet resistance in a field between 5×10 −2 and 7×10 4  Oe over the last one and a half years as a function of temperature and frequency, from 2 t... [Phys. Rev. B 90, 214513] Published Thu Dec 11, 2014

Beschreibung: Author(s): Hiromi Otsuka We present an algorithm for Monte Carlo simulations of a nearest-neighbor spin-ice model based on its cluster representation. To assess its performance, we estimate a relaxation time, and find that, in contrast to the Metropolis algorithm, our algorithm does not develop spin freezing. Also, to demon... [Phys. Rev. B 90, 220406] Published Thu Dec 11, 2014

Beschreibung: Author(s): Hongbin Yao, Wei Guo, Mark R. Hoffmann, and Keli Han We demonstrate an efficient scheme for controlling the tunneling ionization of a H 2 + molecular ion. Our scheme is based on the idea that the tunneling ionization rate is highly dependent on the instantaneous magnitude of the electric field. By manipulating the relative phase of the synthesized 5-fs,... [Phys. Rev. A 90, 063418] Published Thu Dec 11, 2014

Beschreibung: Author(s): Wenkui Ding, Anqi Shi, J. Q. You, and Wenxian Zhang We numerically investigate the encoding and retrieval processes for quantum memory realized in a semiconductor quantum dot by focusing on the effect of inhomogeneously polarized nuclear spins whose polarization depends on the local hyperfine coupling strength. We find that the performance of quantum... [Phys. Rev. B 90, 235421] Published Thu Dec 11, 2014

Beschreibung: Author(s): Sam Morley-Short, Lawrence Rosenfeld, and Pieter Kok The study of quantum systems evolving from initial states to distinguishable, orthogonal final states is important for information processing applications such as quantum computing and quantum metrology. However, for most unitary evolutions and initial states the system does not evolve to an orthogo... [Phys. Rev. A 90, 062116] Published Thu Dec 11, 2014

Beschreibung: Author(s): Chaitanya Joshi, Patrik Öhberg, James D. Cresser, and Erika Andersson We investigate how to model Markovian evolution of coupled harmonic oscillators, each of them interacting with a local environment. When the coupling between the oscillators is weak, dissipation may be modeled using local Lindblad terms for each of the oscillators in the master equation, as is commo... [Phys. Rev. A 90, 063815] Published Thu Dec 11, 2014

Beschreibung: Author(s): Yoshihito Kuno, Keita Suzuki, and Ikuo Ichinose In this paper, we study an extended bosonic t-J model in an optical lattice, which describes two-component hard-core bosons with nearest-neighbor pseudospin interactions and, also, inter- and intraspecies dipole-dipole interactions. In particular, we focus on the case in which two-component hard-cor... [Phys. Rev. A 90, 063620] Published Thu Dec 11, 2014

Beschreibung: Author(s): Jixia Dai, Kristjan Haule, J. J. Yang, Y. S. Oh, S-W. Cheong, and Weida Wu Layered 5d transition metal dichalcogenide (TMD) IrTe 2 is distinguished from the traditional TMDs (such as NbSe 2 ) by the existence of multiple charge-density wave (CDW)-like stripe phases and superconductivity at low temperatures. Despite intensive studies, there is still no consensus on the physica... [Phys. Rev. B 90, 235121] Published Thu Dec 11, 2014

Beschreibung: Author(s): Martin Doškář, Jan Novák, and Jan Zeman The paper presents a concept to compress and synthesize complex material morphologies that is based on Wang tilings. Specifically, a microstructure is stored in a set of Wang tiles and its reconstruction is performed by means of a stochastic tiling algorithm. A substantial part of the study is devot... [Phys. Rev. E 90, 062118] Published Thu Dec 11, 2014

Beschreibung: Author(s): A. Le Yaouanc, L. Oliver, and J.-C. Raynal We pursue the group-theoretical method to study Isgur-Wise (IW) functions. We extend the general formalism, formerly applied to the baryon case j P =0 + (for Λ b →Λ c ℓν̅ ℓ ), to mesons with j P =1/2 - , i.e. B̅ →D(D (*) )ℓν. In this case, which is more involved from the angular momentum point of vi... [Phys. Rev. D 90, 114016] Published Thu Dec 11, 2014

Beschreibung: Author(s): D. Fuster, J. M. Conoir, and T. Colonius We study the influence of bubble-bubble interactions on the propagation of linear acoustic waves in bubbly liquids. Using the full model proposed by Fuster and Colonius [J. Fluid Mech. 688 , 253 (2011)JFLSA710.1017/jfm.2011.380], numerical simulations reveal that direct bubble-bubble interactions hav... [Phys. Rev. E 90, 063010] Published Thu Dec 11, 2014

Beschreibung: Author(s): Felix Yndurain Using ab initio methods based on the density functional theory, we study the magnetic properties of different point defects in graphene. We consider separately, atomic hydrogen, atomic fluorine, and single vacancies. The three defects have completely different magnetic properties. A local spin one-h... [Phys. Rev. B 90, 245420] Published Thu Dec 11, 2014

Beschreibung: Author(s): Kees Wapenaar In time-reversal acoustics, waves recorded at the boundary of a strongly scattering medium are sent back into the medium to focus at the original source position. This requires that the medium can be accessed from all sides. We discuss a focusing method for media that can be accessed from one side o... [Phys. Rev. E 90, 063202] Published Thu Dec 11, 2014

Beschreibung: Author(s): Alan Heavens, Raul Jimenez, and Licia Verde A measure of how galaxies are spatially distributed can be determined in a new, more robust way. [Phys. Rev. Lett. 113, 241302] Published Thu Dec 11, 2014

Beschreibung: Author(s): Ya-Bo Wu, Jun-Wang Lu, Wen-Xin Zhang, Cheng-Yuan Zhang, Jian-Bo Lu, and Fang Yu In the probe limit, we numerically construct a holographic p-wave superfluid model in the four-dimensional (4D) and five-dimensional (5D) anti-de Sitter black holes coupled to a Maxwell-complex vector field. We find that, for the condensate with the fixed superfluid velocity, the results are similar... [Phys. Rev. D 90, 126006] Published Thu Dec 11, 2014

Beschreibung: Author(s): Douglas Stanford and Leonard Susskind In this paper we refine a conjecture relating the time-dependent size of an Einstein-Rosen bridge (ERB) to the computational complexity of the dual quantum state. Our refinement states that the complexity is proportional to the spatial volume of the ERB. More precisely, up to an ambiguous numerical ... [Phys. Rev. D 90, 126007] Published Thu Dec 11, 2014

Beschreibung: Author(s): A. Ludwig, J. Maurer, B. W. Mayer, C. R. Phillips, L. Gallmann, and U. Keller We report the breakdown of the electric dipole approximation in the long-wavelength limit in strong-field ionization with linearly polarized few-cycle mid-infrared laser pulses at intensities on the order of 10 13   W/cm 2 . Photoelectron momentum distributions were recorded by velocity map imaging and ... [Phys. Rev. Lett. 113, 243001] Published Thu Dec 11, 2014

Beschreibung: Author(s): N. Y. Yao, C. R. Laumann, S. Gopalakrishnan, M. Knap, M. Müller, E. A. Demler, and M. D. Lukin Systems of strongly interacting dipoles offer an attractive platform to study many-body localized phases, owing to their long coherence times and strong interactions. We explore conditions under which such localized phases persist in the presence of power-law interactions and supplement our analytic... [Phys. Rev. Lett. 113, 243002] Published Thu Dec 11, 2014

Beschreibung: Spin-dependent transport properties in CoFe/MgO/n + -Si junctions were investigated by Hanle effect measurements and inelastic electron tunneling (IET) spectroscopy. The CoFe/MgO/n + -Si junctions examined in this study exhibited two different Hanle curves. In the low bias region, broad Hanle signals were mainly observed; in the high bias region, narrow Hanle signals were mainly observed. The d 2 I / dV 2 - V curves (which correspond to IET spectra) contain several peaks originating from phonon modes and other peaks originating from electron trap states. At the bias voltage where electron trap states are observed, Δ d 2 I / dV 2 depends on the magnetic field and the full width at half-maximum of the Δ d 2 I / dV 2 – H curves corresponds to that of the broad Hanle signals. These results indicate that electron trap states are located in the low energy region and cause a decrease in spin lifetime.

Beschreibung: We elucidate a strong room temperature stimulated emission (SE) of In 0.17 Ga 0.83 N epilayer grown by molecular beam epitaxy under the subpicosecond pulse excitation. The SE peak at 428 nm emerges on the higher energy side of the spontaneous emission in photoluminescence spectra when the excitation density exceeds the threshold of ∼3.68 mJ/cm 2 . Nondegenerate transient differential reflectivity measurements show that a multi-stage carrier thermalization from excited states to localized edge states and stimulated emission dominate the decay processes of photogenerated carriers under various excitation densities. Our results indicate that the existence of phonon bottleneck effect could result in a slow thermalization process in the InGaN material even under the condition of stimulated emission.

Beschreibung: The relationship between carrier concentration and donor atomic concentration has been determined in n -type Ge films doped with P. The samples were carefully engineered to minimize non-active dopant incorporation by using specially designed P(SiH 3 ) 3 and P(GeH 3 ) 3 hydride precursors. The in situ nature of the doping and the growth at low temperatures, facilitated by the Ge 3 H 8 and Ge 4 H 10 Ge sources, promote the creation of ultra-low resistivity films with flat doping profiles that help reduce the errors in the concentration measurements. The results show that Ge deviates strongly from the incomplete ionization expected when the donor atomic concentration exceeds N d  = 10 17  cm −3 , at which the energy separation between the donor and Fermi levels ceases to be much larger than the thermal energy. Instead, essentially full ionization is seen even at the highest doping levels beyond the solubility limit of P in Ge. The results can be explained using a model developed for silicon by Altermatt and coworkers, provided the relevant model parameter is properly scaled. The findings confirm that donor solubility and/or defect formation, not incomplete ionization, are the major factors limiting the achievement of very high carrier concentrations in n -type Ge. The commercially viable chemistry approach applied here enables fabrication of supersaturated and fully ionized prototypes with potential for broad applications in group-IV semiconductor technologies.

Beschreibung: We developed a T-gate technology based on selective wet etching yielding 200 nm wide T-gate structures used for fabrication of High Electron Mobility Transistors (HEMT). Major advantages of our process are the use of only standard photolithographic process and the ability to generate T-gate stacks. A HEMT fabricated on AlGaN/GaN/sapphire with gate length L g  = 200 nm and double-stacked T-gates exhibits 60 GHz cutoff frequency showing ten-fold improvement compared to 6 GHz for the same device with 2  μ m gate length. HEMTs with a double-level-T-gate (DLTG) structure exhibit up to 35% improvement of f max value compared to a single T-gate device. This indicates a significant reduction of skin effect losses in DLTG structure compared to its standard T-gate counterpart. These results agree with the theoretical predictions.

Beschreibung: This investigation analyzes the effect of vortex wakes on the Lagrangian displacement of particles induced by the passage of an obstacle in a two-dimensional incompressible and inviscid fluid. In addition to the trajectories of individual particles, we also study their drift and the corresponding total drift areas in the Föppl and Kirchhoff potential flow models. Our findings, which are obtained numerically and in some regimes are also supported by asymptotic analysis, are compared to the wakeless potential flow which serves as a reference. We show that in the presence of the Föppl vortex wake, some of the particles follow more complicated trajectories featuring a second loop. The appearance of an additional stagnation point in the Föppl flow is identified as a source of this effect. It is also demonstrated that, while the total drift area increases with the size of the wake for large vortex strengths, it is actually decreased for small circulation values. On the other hand, the Kirchhoff flow model is shown to have an unbounded total drift area. By providing a systematic account of the wake effects on the drift, the results of this study will allow for more accurate modeling of hydrodynamic stirring.

Beschreibung: The magnetic configuration of Mn 2 NiAl ribbon has been investigated. In contrast to Ni 2 MnAl, the compound Mn 2 NiAl with considerable disorder does exhibit ferromagnetism and, due to exchange interaction competition, both ferromagnetic and antiferromagnetic moment orientations can coexist between nearest neighbor Mn atoms. This is unexpected in Heusler alloys. Regarding the mechanism of the martensitic transformation in Mn 50 Ni 50− x Al x , it is found that increasing the Al content results in an unusual change in the lattice constant, a decrease of the transformation entropy change, and enhancement of the calculated electron localization. These results indicate that the p-d covalent hybridization between Mn (or Ni) and Al atoms gradually increases at the expense of the d-d hybridization between Ni and Mn atoms. This leads to an increased stability of the austenite phase and a decrease of the martensitic transformation temperature. For 11 ≤  x  ≤ 14, Mn 50 Ni 50− x Al x ferromagnetic shape memory alloys are obtained.

Beschreibung: Electrowetting (EW) has applications including displays, microactuation, miniaturized chemistry, adaptive optics, and energy harvesting—understanding the physics of EW junctions is of key importance. Here, the roles of semiconductor space-charge and electric double layer in continuous EW at an electrolyte-insulator-semiconductor junction are considered. A model is formulated in terms of experimental parameters—applied voltage, zero-bias wetting contact angle, semiconductor type and doping, insulator thickness and dielectric constant, and electrolyte concentration and dielectric constant. The model predicts, and experiments indicate, that the EW behavior is diminished for low concentration solutions (∼1–10 nM) and lowly doped silicon (10 14 –10 15  cm −3 ).

Beschreibung: The dynamics of the magnetic relaxation process during the sustainment of spheromak configurations at different helicity injection rates is studied. The three-dimensional activity is recovered using time-dependent resistive magnetohydrodynamic simulations. A cylindrical flux conserver with concentric electrodes is used to model configurations driven by a magnetized coaxial gun. Magnetic helicity is injected by tangential boundary flows. Different regimes of sustainment are identified and characterized in terms of the safety factor profile. The spatial and temporal behavior of fluctuations is described. The dynamo action is shown to be in close agreement with existing experimental data. These results are relevant to the design and operation of helicity injected devices, as well as to basic understanding of the plasma relaxation mechanism in quasi-steady state.