bluuebunny/crossref_metadata_2025 huggingface dataset:
The Social Study of Human Rights.A Review Essay
Authors: Niezen Ronald
Published: June 2011

It is noteworthy—and at the same time a bit disappointing in a what-took-so-long sort of way—that a recent innovation in the study of human rights should involve a focus on the lives of the people directly affected by them. To explain this delay of the obvious would probably call for a review of the persistent influence of Kantian transcendentalism, the quasi-utopian search for ideal justice, and the inherently abstract nature of law in its quest for impartiality. A similar effort could be applied toward fully understanding the changed circumstances that encouraged the shift toward practical realism. It would have to take into account the surprisingly late elaboration and popularization of human rights instruments, the proliferation of transnational NGOs that act on new opportunities to exercise moral and political influence, and the growing reach of new technologies of information and communication (necessary tools for the emergence of transnational NGOs). All of these developments have raised the prominence of legal issues and strategies among those once considered isolated and, in varying degrees, uncivilized. But whatever the dominant trends might once have been, and whatever new, enabling circumstances have recently emerged, there can be little doubt that over the last several decades a shift has taken place in the study of human rights toward practical or applied realism, with a focus on ordinary actors.
Fixers in Motion.A Conversation
Authors: Jeffrey Craig , Philliou Christine , Rogers Douglas , Shryock Andrew
Published: June 2011

Since taking the editorial helm ofCSSHin 2006, I have watched several intellectual trends shift and gather momentum. Postsocialist and postcolonial studies are merging into a more generalized interest in the politics of empire. Critical impulses once associated with the “post” approaches have found their way into studies of secularism, conversion, translation, and state effects. Increasingly, these topics are analyzed as transregional processes that operate across religious and political logics. In 2009, our firstCSSHConversation dealt with matters of tolerance and conversion in the Ottoman Empire, and in 2010 we filled an entire issue with essays on secularism (52-3). In each case, the ground we explored was contested, but themes of governmentality and moral transformation were central, and the terms of debate were broadly shared.
Genomic resources for improving food legume crops
Authors: KUMAR J. , PRATAP A. , SOLANKI R. K. , GUPTA D. S. , GOYAL A. , CHATURVEDI S. K. , NADARAJAN N. , KUMAR S.
Published: June 2011

Food legumes are the main source of dietary protein for a large part of the world's population, and also play an important role in maintaining soil fertility through nitrogen fixation. However, legume yields and production are often limited by large genotype×environment (G×E) interactions that influence the expression of agronomically important, complex quantitative traits. Consequently, genetic improvement has been slower than expected. Molecular marker technology enables genetic dissection of such complex traits, allowing breeders to identify genomic regions on the chromosome that have main effects or interactive effects. A number of genomic resources have been developed in several legume species during the last two decades, and provide a platform for exploiting marker technology. The present paper reviews the available genomic resources in food legumes: linkage maps, high-throughput sequencing technologies, expression sequence tag (EST) databases, genome sequences, DNA chips, targeting induced local lesions in genomes (TILLING), bacterial artificial chromosome (BAC) libraries and others. It also describes how these resources are being used to tag and map genes/quantitative trait loci (QTLs) for domesticated and other agronomically important traits. This information is important to genetic improvement efforts aiming at improving food and nutrition security worldwide.
A Roman Engineer's Tales
Authors: Cuomo Serafina
Published: June 2011

This article is an exercise in the historiography of ancient technical artefacts, beginning from the examination of a second-centurya.d.cippus inscribed with the story of a Roman engineer, Nonius Datus, who designed and supervised the construction of an aqueduct in Algeria. The first section looks at the aqueduct from the point of view of the history of engineering. The second traces the history of the inscription as a document in the debate about imperialism and technology. In the third section, the focus is on what Datus himself was trying to communicate. The conclusion makes a case for considering ancient technical artefacts from multiple perspectives.
Extreme value theory and return time statistics for dispersing billiard maps and flows, Lozi maps and Lorenz-like maps
Authors: GUPTA CHINMAYA , HOLLAND MARK , NICOL MATTHEW
Published: June 2011

In this paper we establish extreme value statistics for observations on a class of hyperbolic systems: planar dispersing billiard maps and flows, Lozi maps and Lorenz-like maps. In particular, we show that for time series arising from Hölder observations on these systems which are maximized at generic points the successive maxima of the time series are distributed according to the corresponding extreme value distributions for independent identically distributed processes. These results imply an exponential law for the hitting and return time statistics of these dynamical systems.
Global Democratization: Soup, Society, or System?
Authors: Dryzek John S.
Published: June 2011

Ideas about the presence, absence, and growth of democracy in global politics take different forms. After surveying the basic justifications for global democracy, three frames for making sense of the significance of particular developments and proposals are canvassed. “Soup” involves the proliferation of democratic practices, though the consequences of this proliferation for the overall shape of international politics remain open. “Society” stresses the democratization of processes that affect constitutive norms and discourses. “System” identifies differentiated yet ordered parts, geared to the production of collective outcomes. The soup framing is undemanding yet limited. System provides a way to pinpoint democratic deficiencies and possibilities, but its requirements can be highly demanding, and it leaves open the question of normative integration. Understanding global democratization requires both society and system framings.
Coronary stenting for a muscular bridge in a patient with hypertrophic obstructive cardiomyopathy
Authors: Walters Darren L. , Aroney Con N. , Radford Dorothy J.
Published: June 2011

A young woman with hypertrophic cardiomyopathy presented with intractable chest pain due to a myocardial bridge over the left anterior descending artery, producing severe compression during systole. Percutaneous intracoronary stenting was performed. The patient, however, developed severe and diffuse restenosis within 30 days of the procedure. Myotomy may provide a more effective treatment option for such patients with symptomatic myocardial bridging.
Coding guidelines for Prolog
Authors: COVINGTON MICHAEL A. , BAGNARA ROBERTO , O'KEEFE RICHARD A. , WIELEMAKER JAN , PRICE SIMON
Published: June 2011

Coding standards and good practices are fundamental to a disciplined approach to software projects irrespective of programing languages being employed. Prolog programing can benefit from such an approach, perhaps more than programing in other languages. Despite this, no widely accepted standards and practices seem to have emerged till now. The present paper is a first step toward filling this void: It provides immediate guidelines for code layout, naming conventions, documentation, proper use of Prolog features, program development, debugging, and testing. Presented with each guideline is its rationale and, where sensible options exist, illustrations of the relative pros and cons for each alternative. A coding standard should always be selected on a per-project basis, based on a host of issues pertinent to any given programing project; for this reason the paper goes beyond the mere provision of normative guidelines by discussing key factors and important criteria that should be taken into account when deciding on a full-fledged coding standard for the project.
Effects of Male Anxiety Chemosignals on the Evaluation of Happy Facial Expressions
Authors: Zernecke Rebekka , Haegler Katrin , Kleemann Anna Maria , Albrecht Jessica , Frank Tilman , Linn Jennifer , Brückmann Hartmut , Wiesmann Martin
Published: June 2011

The communication of chemosensory alarm signals is well explored in mammals. In humans the effects of anxiety substances might seem to be less important due to their high-developed visual system, and their sophisticated ability to communicate via speech and body language. Nevertheless, an increasing number of studies suggest an effect of chemosignals of anxiety on human physiology and behavior. In the present study two kinds of human sweat were collected from 21 males during a bicycle workout and a visit of a high rope course, and were then applied to 15 different healthy male participants during an emotion evaluation task. Participants were instructed to rate emotional male faces of different morphing levels (neutral-happy) by using a visual analog scale under exposure of three different samples (exercise sweat, anxiety sweat, and control material). Our study revealed that men rated happy faces as less happy under the influence of anxiety sweat compared to the exercise and the control conditions; significant differences were demonstrated only for ambiguous emotional faces. In conclusion, chemosignals of anxiety comprised in human sweat are communicated between males; they diminish the evaluation of ambiguous happy male facial expressions in men and thereby influence the perception of emotional faces.
Cardiac and Electrophysiological Responses to Valid and Invalid Feedback in a Time-Estimation Task
Authors: Mies G. W. , Van der Veen F. M. , Tulen J. H. M. , Hengeveld M. W. , Van der Molen M. W.
Published: June 2011

This study investigated the cardiac and electrophysiological responses to feedback in a time-estimation task in which feedback-validity was manipulated. Participants across a wide age range had to produce 1 s intervals followed by positive and negative feedback that was valid or invalid (i.e., related or unrelated to the preceding time estimate). Performance results showed that they processed the information provided by the feedback. Negative feedback was associated with a transient cardiac slowing only when feedback was valid. Correct adjustments after valid negative feedback were associated with a more pronounced cardiac slowing. Validity did not affect the feedback-related negativity (FRN), except when remedial action was taken into account. The FRN and cardiac response to feedback decreased with advancing age, but performance did not. The current pattern of findings was interpreted to suggest that the FRN and cardiac response signal “alert” and that the cardiac response, but not the FRN, is implicated in the mechanisms invoked in remedial action.
Suspension and near‐bed load sediment transport processes above a migrating, sand‐rippled bed under shoaling waves
Authors: Hurther D. , Thorne Peter D.
Published: June 2011

The present study focuses on the fine‐scale flow and sand transport processes above onshore migrating ripples below skewed surface gravity waves in the shoaling zone. A set of acoustic instruments was deployed in the shoaling region of the large‐scale wave channel at Canal d'Investigacío i Experimatacío Marítima, Universitat Poltiècnica de Catalunya, Barcelona, Spain, in order to provide high‐resolution velocity and sediment concentration profiles with an acoustic concentration and velocity profiler (ACVP). Measurements are analyzed relative to the positions of the measured nonmoving sand bed and the interface separating the suspension from the near‐bed load layer. This interface is detected here by the application of a novel acoustic bed echo detection method. Furthermore, the use of the dual‐frequency inversion proposed in the work of Hurther et al. (2011) allows for the calculation of the sediment concentration profile across both the suspension and near‐bed load layers. The sand bed was covered by quasi‐two‐dimensional suborbital ripples migrating onshore. As proposed by O'Donoghue et al. (2006), the occurrence of quasi‐two‐dimensional ripples is attributed to the fine‐size sand ofD50= 250μm used in the present study under full‐scale forcing conditions. In order to determine the effect of shoaled wave skewness on the ripple vortex entrainment and sediment transport, the instantaneous and mean measurements of the flow, sediment concentration, and sediment flux along the ripple profile are discussed in terms of (1) the occurrence of ripple vortex entrainment on either side of the ripple crest; (2) the wave velocity phase lagging driven by the ripple vortex entrainment process and the turbulent bed friction effects in the wave boundary layer; (3) phase lagging between velocity and maximum concentration and sediment flux events; (4) the structure of bed friction and ripple‐driven turbulence across the suspension and the near‐bed load layers; and (5) the streaming components. The results on these aspects strongly support that the wave velocity skewness effect under shoaling waves is fairly similar to the one obtained in skewed oscillatory water tunnel flows. Furthermore, it is found that the onshore‐oriented net bed load sediment transport is at the origin of the onshore ripple migration. This flux is roughly twice as much as the opposite offshore‐oriented net suspension flux dominated by the ripple vortex entrainment processes.
The oral metagenome in health and disease
Authors: Belda-Ferre Pedro , Alcaraz Luis David , Cabrera-Rubio Raúl , Romero Héctor , Simón-Soro Aurea , Pignatelli Miguel , Mira Alex
Published: June 2011

The oral cavity of humans is inhabited by hundreds of bacterial species and some of them have a key role in the development of oral diseases, mainly dental caries and periodontitis. We describe for the first time the metagenome of the human oral cavity under health and diseased conditions, with a focus on supragingival dental plaque and cavities. Direct pyrosequencing of eight samples with different oral-health status produced 1 Gbp of sequence without the biases imposed by PCR or cloning. These data show that cavities are not dominated by Streptococcus mutans (the species originally identified as the ethiological agent of dental caries) but are in fact a complex community formed by tens of bacterial species, in agreement with the view that caries is a polymicrobial disease. The analysis of the reads indicated that the oral cavity is functionally a different environment from the gut, with many functional categories enriched in one of the two environments and depleted in the other. Individuals who had never suffered from dental caries showed an over-representation of several functional categories, like genes for antimicrobial peptides and quorum sensing. In addition, they did not have mutans streptococci but displayed high recruitment of other species. Several isolates belonging to these dominant bacteria in healthy individuals were cultured and shown to inhibit the growth of cariogenic bacteria, suggesting the use of these commensal bacterial strains as probiotics to promote oral health and prevent dental caries.
Factors Predicting Nongenetic Variability in Body Weight Gain Induced by a High‐Fat Diet in Inbred C57BL/6J Mice
Authors: Zhang Li‐Na , Morgan David G. , Clapham John C. , Speakman John R.
Published: June 2011

Inbred C57BL/6J mice displayed large individual variations in weight gain when fed a high‐fat diet (HFD). The objective of this study was to examine whether this predominantly nongenetic variability could be predicted by relevant baseline features and to explore whether variations in these significant features were influenced during pregnancy and/or lactation. Fat mass (FM), fat‐free mass (FFM), food intake (FI), resting metabolic rate (RMR), physical activity (PA), and body temperature (Tb) were all evaluated at baseline in 60 mice (aged 10–12 weeks) before HFD feeding. Regression analyses showed that baseline FM was a strong positive predictor of weight gain between 4 and 16 weeks of HFD. Baseline PA was negatively associated with weight gain at week 8, 12, and 16, and baseline FFM had a positive effect at week 12 and 16. In a second experiment, 40 female mice were mated and litter sizes (LS) were manipulated on day 3 of lactation. Weaning weight and postweaning growth rate (GR) had positive impacts on FM and FFM at age 9 weeks (FM, P = 0.001; FFM, P < 0.001: n = 97). Lactation LS had a negative effect on weaning weight and a positive effect on postweaning GR. In conclusion, our results show that obesity induced by HFD was associated with a higher baseline FM, a higher baseline FFM and a lower baseline PA level before the exposure of HFD. Two of these traits (FM and FFM) were influenced by lactation LS via weaning weight and postweaning GR.
Beverage vs. Solid Fruits and Vegetables: Effects on Energy Intake and Body Weight
Authors: Houchins Jenny A. , Burgess John R. , Campbell Wayne W. , Daniel James R. , Ferruzzi Mario G. , McCabe George P. , Mattes Richard D.
Published: June 2011

Beverage consumption has been implicated in weight gain, but questions remain about the veracity of the association, whether the relationship is causal and what property of beverages is responsible. It was hypothesized that food form is the most salient attribute. Thus, a randomized controlled trial of food form was conducted. Energy‐matched beverage or solid forms of fruits and vegetables were provided to 34, lean or overweight/obese adults for two 8‐week periods with a 3‐week washout interspersed. Dietary compensation was incomplete (beverage 53% solid 78%) and body weight increased after the beverage (1.95 ± 0.33 kg) (77% fat mass) and solid (1.36 ± 0.30 kg) (85% fat mass) treatments (both P < 0.0005). Differences between food forms were not significant. The lean group had the highest dietary compensation (119%) and no significant weight change (0.84 ± 0.53 kg) after consuming the solid fruits and vegetables whereas the overweight/obese group had lower compensation and significant weight gain during the solid arm (46%, 1.77 ± 0.32 kg, P < 0.0001). In contrast, incomplete dietary compensation and weight gain occurred in both the lean (43%, 1.61 ± 0.44 kg, P = 0.003) and overweight/obese (61%, 2.22 ± 0.47 kg, P < 0.0005) groups during the beverage arm. Secondary analyses revealed the obese group gained more weight than the lean and overweight groups during the beverage intervention (P = 0.024). These data demonstrate energy consumed as beverages may be especially problematic for weight gain. They also indicate that advice to increase fruit and vegetable consumption should emphasize total energy intake because the additional energy contributed may promote weight gain, especially among overweight and obese individuals.
A Randomized Pilot Trial of a Full Subsidy vs. a Partial Subsidy for Obesity Treatment
Authors: Tsai Adam G. , Felton Sue , Hill James O. , Atherly Adam J.
Published: June 2011

Intensive obesity treatment is mandated by federal health care reform but is costly. A partial subsidy for obesity treatment could lower the cost of treatment, without reducing its efficacy. This study sought to test whether a partial subsidy for obesity treatment would be feasible, as compared to a fully subsidized intervention. The study was a pilot randomized trial. Participants (n = 50) were primary care patients with obesity and at least one comorbid condition (diabetes, hypertension, dyslipidemia, or obstructive sleep apnea). Each participant received eight weight loss counseling visits as well as portion‐controlled foods for weight loss. Participants were randomized to full subsidy or partial subsidy (2 vs. 1 meal per day provided). The primary outcome was weight change after 4 months. Secondary outcomes included changes in blood pressure, waist circumference, and health‐related quality of life. Participants in the full and partial subsidy groups lost 5.9 and 5.3 kg, equivalent to 5.3% and 5.1% of initial weight, respectively (P = 0.71). Changes in secondary outcomes were similar in the two groups. A partial subsidy was feasible and induced a clinically similar amount of weight loss, compared to a full subsidy. Large‐scale testing of economic incentives for weight control is merited given the federal mandate to offer weight loss counseling to obese patients.
Weight Perceptions Among Overweight and Obese Women: A US‐Mexico Binational Perspective
Authors: Guendelman Sylvia , Ritterman‐Weintraub Miranda L. , Fernald Lia C.H. , Kaufer‐Horwitz Martha
Published: June 2011

We examined actual and perceived weight in nationally representative cohorts of adults in Mexico (n = 9,527) and the United States (n = 855) using data from the National Health and Nutrition Examination Survey (waves 2001–2006) and Mexican National Health and Nutrition Survey (2006). Actual weight was assessed by health technicians using BMI and perceived weight was collected through self‐report. The prevalence of overweight or obesity (OO) in Mexican women was 72% and in Mexican‐American women was 71%. OO Mexican‐American women were more likely than OO Mexican women to label themselves as “overweight” (86% vs. 64%, P < 0.001), and this difference was significant while controlling for socio‐demographic and weight‐related variables. Among OO women from both populations, those who had been told by a health provider that they were OO were much more likely to perceive themselves as such (odds ratio = 5.3; 95% confidence intervals: 3.8–7.3). Significantly fewer OO women in Mexico than in the United States (13% vs. 42%, P < 0.0001) recalled having been screened for obesity by their health care provider. Weight misperceptions were common in both populations but more prevalent in Mexico, and low screening by health providers may be an important contributor to poor weight control in both countries.
Impact of High‐Fat Diet and Obesity on Energy Balance and Fuel Utilization During the Metabolic Challenge of Lactation
Authors: Wahlig Jessica L. , Bales Elise S. , Jackman Matthew R. , Johnson Ginger C. , McManaman James L. , MacLean Paul S.
Published: June 2011

The effects of obesity and a high‐fat (HF) diet on whole body and tissue‐specific metabolism of lactating dams and their offspring were examined in C57/B6 mice. Female mice were fed low‐fat (LF) or HF diets before and throughout pregnancy and lactation. HF‐fed mice were segregated into lean (HF‐Ln) and obese (HF‐Ob) groups before pregnancy by their weight gain response. Compared to LF‐Ln dams, HF‐Ln, and HF‐Ob dams exhibited a greater positive energy balance (EB) and increased dietary fat retention in peripheral tissues (P < 0.05). HF‐Ob dams had greater dietary fat retention in liver and adipose compared to HF‐Ln dams (P < 0.05). De novo synthesized fat was decreased in tissues and milk from HF‐fed dams compared to LF‐Ln dams (P < 0.05). However, less dietary and de novo synthesized fat was found in the HF‐Ob mammary glands compared to HF‐Ln (P < 0.05). Obesity was associated with reduced milk triglycerides relative to lean controls (P < 0.05). Compared to HF diet alone obesity has additional adverse affects, impairing both lipid metabolism as well as milk fat production. Growth rates of LF‐Ln litters were lower than HF‐Ln and HF‐Ob litters (P < 0.05). Total energy expenditure (TEE) of HF‐Ob litters was reduced relative to HF‐Ln litters, whereas their respiratory exchange ratios (RERs) were increased (P < 0.05). Collectively these data show that consumption of a HF diet significantly affects maternal and neonatal metabolism and that maternal obesity can independently alter these responses.
A microfluidic-based neurotoxin concentration gradient for the generation of an in vitro model of Parkinson’s disease
Authors: Seidi Azadeh , Kaji Hirokazu , Annabi Nasim , Ostrovidov Serge , Ramalingam Murugan , Khademhosseini Ali
Published: June 2011

In this study, we developed a miniaturized microfluidic-based high-throughput cell toxicity assay to create an in vitro model of Parkinson’s disease (PD). In particular, we generated concentration gradients of 6-hydroxydopamine (6-OHDA) to trigger a process of neuronal apoptosis in pheochromocytoma PC12 neuronal cell line. PC12 cells were cultured in a microfluidic channel, and a concentration gradient of 6-OHDA was generated in the channel by using a back and forth movement of the fluid flow. Cellular apoptosis was then analyzed along the channel. The results indicate that at low concentrations of 6-OHDA along the gradient (i.e., approximately less than 260 μM), the neuronal death in the channel was mainly induced by apoptosis, while at higher concentrations, 6-OHDA induced neuronal death mainly through necrosis. Thus, this concentration appears to be useful for creating an in vitro model of PD by inducing the highest level of apoptosis in PC12 cells. As microfluidic systems are advantageous in a range of properties such as throughput and lower use of reagents, they may provide a useful approach for generating in vitro models of disease for drug discovery applications.
Evolution of nanostructure, defect-free photoluminescence and enhanced photoconductivity of oxidized Zn films
Authors: Koshy Obey , Khadar M. Abdul
Published: June 2011

Nanostructured zinc oxide thin films were prepared by the oxidation of nanostructured zinc films deposited on glass substrates by thermal evaporation of metallic zinc in an atmosphere of nitrogen. The films were oxidized at different temperatures. X-ray diffraction was used to study the structural transformations of the films with oxidation temperature. Atomic force microscopy images of surface morphology of the films revealed the kinetics of aggregation of the grains as the oxidation temperature was increased. Raman spectra of the samples contained a surface mode at ∼482 cm−1 showing characteristics of fine grain size. UV-Visible absorption spectra of the samples showed a blueshift of bandgap in comparison with that of bulk ZnO crystals. The photoluminescence emission spectra of the samples were free from defect related emissions. The increase in oxidation temperature of these samples caused a narrowing of the photoluminescent emission band in the UV region and an increase in the UV photocurrent. The ratio of maximum photocurrent to dark current was found to increase from 100 to 2000 as the oxidation temperature of the films increased from 350 to 500 showing an enhanced photoconductivity. The increased photocurrent was attributed to the interconnected grain structure of the ZnO samples oxidized at higher temperature.
Cis-trans isomerization in the S1 state of acetylene: Identification of cis-well vibrational levels
Authors: Merer Anthony J. , Steeves Adam H. , Baraban Joshua H. , Bechtel Hans A. , Field Robert W.
Published: June 2011

A systematic analysis of the S1-trans (${\rm \tilde A}$Ã1Au) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment of at least part of every single vibrational state or polyad up to a vibrational energy of 4200 cm–1. Four observed vibrational levels remain unassigned, for which no place can be found in the level structure of the trans-well. The most prominent of these lies at 46 175 cm−1. Its 13C isotope shift, exceptionally long radiative lifetime, unexpected rotational selection rules, and lack of significant Zeeman effect, combined with the fact that no other singlet electronic states are expected at this energy, indicate that it is a vibrational level of the S1-cis isomer (${\rm \tilde A}$Ã1A2). Guided by ab initio calculations [J. H. Baraban, A. R. Beck, A. H. Steeves, J. F. Stanton, and R. W. Field, J. Chem. Phys. 134, 244311 (2011)]10.1063/1.3570823 of the cis-well vibrational frequencies, the vibrational assignments of these four levels can be established from their vibrational symmetries together with the 13C isotope shift of the 46 175 cm−1 level (assigned here as cis-3161). The S1-cis zero-point level is deduced to lie near 44 900 cm−1, and the ν6 vibrational frequency of the S1-cis well is found to be roughly 565 cm−1; these values are in remarkably good agreement with the results of recent ab initio calculations. The 46 175 cm−1 vibrational level is found to have a 3.9 cm−1 staggering of its K-rotational structure as a result of quantum mechanical tunneling through the isomerization barrier. Such tunneling does not give rise to ammonia-type inversion doubling, because the cis and trans isomers are not equivalent; instead the odd-K rotational levels of a given vibrational level are systematically shifted relative to the even-K rotational levels, leading to a staggering of the K-structure. These various observations represent the first definite assignment of an isomer of acetylene that was previously thought to be unobservable, as well as the first high resolution spectroscopic results describing cis-trans isomerization.
The effect of disorder on the valley-dependent transport in zigzag graphene nanoribbons
Authors: Zhang Ying-Tao , Sun Qing-feng , Xie X. C.
Published: June 2011

We investigate the electron transport through a zigzag graphene nanoribbon with a staggered sublattice potential and a certain asymmetric boundary potential. By using the tight binding model to combine with the nonequilibrium Green’s function theory and the Landauer–Büttiker formalism, the energy band structure, conductance, and conductance fluctuation are calculated. We find that an energy gap opens up due to the inversion symmetry breaking by the staggered sublattice potential. By further tuning the boundary potential, the gapless valley-dependent edge states are achieved in which the carriers with the different valleys on a given boundary propagate in opposite directions. Furthermore, we study the effect of long range disorder on the transport properties of the valley-dependent edge states. The results show that the conductance plateau 4e2/h contributed by the edge states can be maintained well in a broad range of disorder strength for low-density disorder, indicating the robustness of the valley-dependent transport. In addition, the conductance fluctuation is also studied, and the fluctuation almost vanishes at weak disorder. On the other hand, at intermediate disorder strength with the system in the diffusive regime, the universal conductance fluctuation is exhibited. The conductance fluctuation is independent of various parameters, e.g., the ribbon width, the disorder range, and the disorder density.
First results from the modular multi-channel dispersion interferometer at the TEXTOR tokamak
Authors: Dreier H. , Bagryansky P. , Baumgarten N. , Biel W. , Lambertz H. T. , Lehnen M. , Lizunov A. , Solomakhin A.
Published: June 2011

At the TEXTOR tokamak in Jülich, Germany, a modular dispersion interferometer was installed and operated for the first time. Equipped with four lines of sight, the line-integrated density could be measured in parallel at different major radii with a resolution of better than 3 × 1017 m−2. This paper will describe the setup and show the first measurement results. Among others, it was possible to detect the evolution of a disruption with a time resolution of 4 μs. The movement of the runaway beam following the disruption could be resolved spatially and temporarily.
A Zeeman slower design with permanent magnets in a Halbach configuration
Authors: Cheiney P. , Carraz O. , Bartoszek-Bober D. , Faure S. , Vermersch F. , Fabre C. M. , Gattobigio G. L. , Lahaye T. , Guéry-Odelin D. , Mathevet R.
Published: June 2011

We describe a simple Zeeman slower design using permanent magnets. Contrary to common wire-wound setups, no electric power and water cooling are required. In addition, the whole system can be assembled and disassembled at will. The magnetic field is however transverse to the atomic motion and an extra repumper laser is necessary. A Halbach configuration of the magnets produces a high quality magnetic field and no further adjustment is needed. After optimization of the laser parameters, the apparatus produces an intense beam of slow and cold 87Rb atoms. With typical fluxes of (1–5) × 1010 atoms/s at 30 m s−1, our apparatus efficiently loads a large magneto-optical trap with more than 1010 atoms in 1 s, which is an ideal starting point for degenerate quantum gas experiments.
Characteristics of Al substituted nanowires fabricated by self-aligned growth for future large scale integration interconnects
Authors: Kudo Hiroshi , Kurahashi Teruo
Published: June 2011

Substituted Al nanowires for use in future large scale integration interconnects were fabricated by self-aligned growth. The resistivity of an Al substituted nanowire 80 nm in width, 100 nm in height, and 20 μm in length was 4.7 μΩ cm, which is 48% lower than that of an Al nanowire with the same dimensions fabricated using a bottom-up approach. The variation in the resistivity was in a narrow range (14%) over a Si wafer. The TEM imaging revealed that the Al substituted nanowire had a bamboo-like structure with grains larger than 1.6 μm. The electromigration activation energy was 0.72 eV, which is comparable to that of a pure Al wire with a bamboo-like structure. The product of the critical current density and wire length was 1.3 × 103 A/cm at 250 °C; 2.1 times higher than that of a pure Al wire with a polycrystalline structure. The acceleration of electromigration due to current density was 2.0, indicating that incubation time dominates electromigration lifetime. The prolonged incubation time observed in the electromigration test is attributed to the reduction in electromigration-induced mass transport due to the microstructure of the Al substituted nanowire. Even the formation of a small void immediately after incubation may be a fatal defect for nanoscale Al wires.
A semi-discrete scheme for solving nonlinear hyperbolic-type partial integro-differential equations using radial basis functions
Authors: Avazzadeh Z. , Rizi Z. Beygi , Ghaini F. M. Maalek , Loghmani G. B.
Published: June 2011

In this paper, we propose an effective numerical method for solving nonlinear Volterra partial integro-differential equations. These equations include the partial differentiations of an unknown function and the integral term containing the unknown function as the “memory” of system. Radial basis functions and finite difference method as the main techniques play the important role to reduce a nonlinear partial integro-differential equation to a linear system of equations. Some examples are demonstrated to describe the method. Numerical results confirm the validity and efficiency of the presented method.
Interlayer exchange coupling in GaN-based diluted magnetic semiconductor multilayers studied by first-principles calculations
Authors: Luo M. , Tang Z. , Zhu Z. Q. , Chu J. H.
Published: June 2011

Interlayer exchange coupling (IEC) in a series model diluted magnetic semiconductor (DMS) multilayer consisting of two magnetic (Ga, M)N (M = Mn or Cu) layers separated by non-doped or Mg-doped GaN non-magnetic spacers has been studied by first-principles calculations. The effects of the spacer thickness and of the hole doping to the IEC were studied systematically. It is observed that (1) without Mg doping, the IEC between two magnetic (Ga, M)N (M = Mn or Cu) layers is always ferromagnetic, which is clarified as an intrinsic character of the Ruderman–Kittle–Kasuya–Yoshida interaction in a two dimensional gaped system; (2) with Mg doping into the GaN spacer, the IEC is tunable from ferromagnetic to antiferromagnetic by varying the spacer’s thickness and the dopant’s site. It is found that the significant hybridization between the Cu and Mg dopants contributes considerable density of states around the Fermi energy level and thus enhances the magnetic interaction between the Cu-doped magnetic layers, indicating that Cu is a better dopant for device application of the GaN-based DMS multilayers.
Decoherence and surface hopping: When can averaging over initial conditions help capture the effects of wave packet separation?
Authors: Subotnik Joseph E. , Shenvi Neil
Published: June 2011

Fewest-switches surface hopping (FSSH) is a popular nonadiabatic dynamics method which treats nuclei with classical mechanics and electrons with quantum mechanics. In order to simulate the motion of a wave packet as accurately as possible, standard FSSH requires a stochastic sampling of the trajectories over a distribution of initial conditions corresponding, e.g., to the Wigner distribution of the initial quantum wave packet. Although it is well-known that FSSH does not properly account for decoherence effects, there is some confusion in the literature about whether or not this averaging over a distribution of initial conditions can approximate some of the effects of decoherence. In this paper, we not only show that averaging over initial conditions does not generally account for decoherence, but also why it fails to do so. We also show how an apparent improvement in accuracy can be obtained for a fortuitous choice of model problems, even though this improvement is not possible, in general. For a basic set of one-dimensional and two-dimensional examples, we find significantly improved results using our recently introduced augmented FSSH algorithm.
Polarized Raman spectroscopic study on the solvent state of glassy LiCl aqueous solutions and the state of relaxed high-density amorphous ices
Authors: Suzuki Yoshiharu , Tominaga Yasunori
Published: June 2011

We measure polarized OH-stretching Raman spectra of the glassy lithium chloride aqueous solutions (LiClaq solutions) and the relaxed high-density amorphous ices (HDA). The totally OH symmetric vibrational mode around 3100 cm−1 (g1 mode) for the glassy LiClaq solutions of 14.3 mol% and the g1 mode for the glassy LiClaq solution of 10.0 mol% seem to be similar to the g1 mode for HDA at high pressure and the g1 mode for HDA at 1 atm, respectively. This indicates that the solvent state of glassy LiClaq solution relates to the state of HDA and that the attenuation of the salt effect on water is equivalent to the attenuation of the pressure effect on water. This suggests a possibility that the hydration in electrolyte aqueous solution may relate to high-density liquid water.
Bandgap engineering of sol-gel synthesized amorphous Zn1−xMgxO films
Authors: Wei M. , Boutwell R. C. , Mares J. W. , Scheurer A. , Schoenfeld W. V.
Published: June 2011

Amorphous Zn1−xMgxO (α-Zn1−xMgxO) ternary alloy thin films across the full compositional range were synthesized by a low-cost sol-gel method on quartz substrates. The amorphous property of the α-Zn1−xMgxO films was verified by x-ray diffraction, and atomic force microscopy revealed a smooth surface with sub-nanometer root-mean square roughness. The current phase segregation issue limiting application of crystalline Zn1−xMgxO with 38% < x < 75% was completely eliminated by growing amorphous films. Optical transmission measurements showed high transmissivity of more than 90% in the visible and near infrared regions, with optical bandgap tunability from 3.3 eV to more than 6.5 eV by varying the Mg content.
Ultrafast magnetization dynamics in magnetic tunneling junctions
Authors: Zou Xiaojing , Xiao Gang
Published: June 2011

To understand the dynamic magnetic properties and its relationship to ultrafast field sensing, we performed micromagnetic simulations on actual MgO-based magnetic tunneling junction (MTJ) structures. The results indicate that an MTJ with a larger aspect ratio yields a smaller response time under a sudden change of an external magnetic field. Such an effect is mainly due to the coherent rotation from the central cores inside the junction element. Damping coefficient is shown to play an important role in ultrafast sensing and the optimal value need to be a few times larger than typical values found in common ferromagnetically soft materials. Our calculations further show that the response time can be reduced by increasing the free layer thickness and/or its saturation magnetization. Finally, we have obtained the dependence of intrinsic resonance frequency on the sensor size while keeping the same aspect ratio.
Trigonal distortion of topologically confined channels in bilayer graphene
Authors: Núñez A. S. , Suárez Morell E. , Vargas P.
Published: June 2011

In this work, we show that the trigonal warping of the electronic bands in bilayer graphene dramatically modifies the behavior of the topologically confined one-dimensional modes due to an inhomogeneous bias that changes sign across a channel. Up to four zero modes are present, depending on the orientation of the channel, these zero modes are related to a fractionalization of the topological charge due to the trigonal warping.
Electrical control of reversible and permanent magnetization reorientation for magnetoelectric memory devices
Authors: Wu Tao , Bur Alexandre , Wong Kin , Zhao Ping , Lynch Christopher S. , Amiri Pedram Khalili , Wang Kang L. , Carman Gregory P.
Published: June 2011

We report giant reversible and permanent magnetic anisotropy reorientation between two perpendicular easy axes in a magnetoelectric polycrystalline Ni thin film and (011) oriented [Pb(Mg1/3Nb2/3)O3](1−x)-[PbTiO3]x (PMN-PT) heterostructure. The PMN-PT is partially poled prior to Ni film deposition to provide a remanent strain bias. Following Ni deposition and full poling of the sample, two giant remanent strains of equal and opposite values are used to reversibly and permanently reorient the magnetization state of the Ni film. These experimental results are integrated into micromagnetic simulation to demonstrate the usefulness of this approach for magnetoelectric based magnetic random access memory.
Direct observation of amplified spontaneous emission of surface plasmon polaritons at metal/dielectric interfaces
Authors: Chen Yu-Hui , Li Jiafang , Ren Ming-Liang , Wang Ben-Li , Fu Jin-Xin , Liu Si-Yun , Li Zhi-Yuan
Published: June 2011

We report on direct observation of amplified spontaneous emission (ASE) of surface plasmon polaritons (SPPs) at the interface of a silver film and a gain medium. Based on a typical Kretschmann configuration incorporated with Rhodamine 6G molecules, the growing ASE spectra of SPPs have been clearly identified by carefully conducting a pump-dependent angle-resolved spectral measurement. Spectral narrowing effects induced by the SPP amplification are also demonstrated. The observed phenomena are helpful in understanding the fundamental interactions between SPPs and gain medium, which could enable wide applications on plasmonic sources and sensors.
Enhanced infrared light harvesting of inorganic nanocrystal photovoltaic and photodetector on graphene electrode
Authors: Lin Chih-Cheng , Wang Di-Yan , Tu Kun-Hua , Jiang You-Ting , Hsieh Meng-Hsiang , Chen Chia-Chun , Chen Chun-Wei
Published: June 2011

We demonstrate an enhancement of infrared light harvesting of inorganic PbS nanocrystal photovoltaic and photodetector devices based on the transparent graphene electrode. Due to high infrared transparency of the graphene electrode with respect to indium tin oxide (ITO), the infrared photoresponse of the graphene-based device is superior to the ITO-based counterpart, in spite of a higher sheet resistance of the graphene electrode. The outstanding infrared characteristics of the devices based on the graphene electrode make it a promising candidate for infrared optoelectronic applications such as solar cells, imaging and sensing, or optical communication.
The effects of charge injection in single-wall carbon nanotubes studied by charge-induced absorption
Authors: Kennedy W. Joshua , Vardeny Z. Valy
Published: June 2011

We studied direct charge injection in a heterogeneous film of single-wall carbon nanotubes using the technique of charge-induced absorption. We found that the injected charges screen the excitons in the semiconducting tubes, reducing their binding energy and transferring oscillator strength from the exciton transitions to free carriers. These effects parallel those of the electrochemical doping in the same samples.
Evaluation of the transient potential drop of a four-point probe
Authors: Bowler J. R.
Published: June 2011

The time-dependent voltage across the pick-up electrodes of a four point probe has been determined analytically for a transient current pulse injected into a thick conductive plate modeled as a half-space. This is a step towards analyzing more complex transient four point probe signals from measurements on inhomogeneous conductors. Potential applications include the evaluation of depth-dependent conductivity profiles in metals and semiconductors. The analysis of homogeneous conductors shows how the signals are characterized by a time constant of the drive current and additional time constants dependent on the electromagnetic material properties and electrode spacings.
An optical-coding method to measure particle distribution in microfluidic devices
Authors: Wu Tsung-Feng , Mei Zhe , Pion-Tonachini Luca , Zhao Chao , Qiao Wen , Arianpour Ashkan , Lo Yu-Hwa
Published: June 2011

We demonstrated an optical coding method to measure the position of each particle in a microfluidic channel. The technique utilizes a specially designed pattern as a spatial mask to encode the forward scattering signal of each particle. From the waveform of the forward scattering signal, one can obtain the information about the particle position and velocity. The technique enables us to experimentally investigate the complex relations between particle positions within the microfluidic channel and flow conditions and particle sizes. The method also produces insight for important phenomenon in microfluidic and lab-on-a-chip devices such as inertial focusing, Dean flow, flow confinement, etc.
Uncertainty and Confidence in Visual Perception
Authors: Mamassian P
Published: June 2011

Visual perception is often seen as an inference problem where uncertainty comes from ambiguities in the world (eg, the two 3D interpretations of the Necker cube), noise in the world (eg, identifying a scene behind falling snowflakes), or noise in the visual system (eg, synaptic noise). Uncertainty not only influences our performance in visual perception tasks (eg, how well can we discriminate between two orientations) but also our confidence in being able to perform these tasks (how well can we predict our performance). We present here the results of three psychophysical experiments that illustrate how uncertainty weakens our perception and how it can determine our confidence in our perceptual decisions. In the first experiment on stereopsis, we show that the same level of uncertainty can lead to very different levels of performance depending on the context. In the next two experiments on orientation discrimination, we show that objective confidence judgments are correlated with discrimination performance and that these confidence judgments are not just based on some visibility cues in the stimulus. Overall, these results open the door for a thorough investigation of the processing of uncertainty by the visual system.
The Vertical Horopter is Not Adaptable and is Not Adaptive for Viewing Along the Ground
Authors: Banks M
Published: June 2011

Helmholtz speculated that the pitch of the vertical horopter is an adaptation for perceiving 3D structure along the ground. We examined this claim by asking whether the horopter is adaptable (ie, whether it is different for people of different heights and whether it can be changed in response to distorting lenses) and whether it's adaptive (ie, whether it really is suited for perceiving along the ground). We find that it is not adaptable in that the pitch of the vertical horopter is not correlated with height and in that it does not change in response to one week of altered visual experience. We also find that it is not adaptive for viewing along the ground because the vertical horopter is a convex curve rather than a line. We speculate that it is adaptive for other aspects of natural viewing.