bluuebunny/crossref_metadata_2025 huggingface dataset:
Qualitative comparative analysis and applied public policy analysis: New applications of innovative methods
Authors: Hudson John , Kühner Stefan
Published: November 2013

QCA based methods have grown in popularity in recent years. Standing between quantitative and qualitative research, in principle they help balance the breadth of analysis provided by quantitative data with the depth of case study knowledge provided by qualitative analysis. The challenge of mixing depth and breadth has always been a particularly acute one for policy based research. Proponents of QCA techniques suggest they are better placed to handle the diversity of policy provision found in different spatial entities than standard linear quantitative methods, while also able to allow for hypothesis testing based upon a fine grained analysis that is more systematic in approach than the techniques typically employed in standard qualitative analyses. The full potential of these methods for policy analysis has yet to be realised however. Partly this is because knowledge of these methods remains at the margins of the policy analysis community, particularly amongst practitioners undertaking applied policy analyses such as policy evaluations. In the introduction to this volume we first outline some of the key principles of QCA research before moving on to identify some of its key advantages. We round off by highlighting key themes explored by the papers included within the volume.
Locomotory capabilities in the Early Cretaceous ichthyosaurPlatypterygius australisbased on osteological comparisons with extant marine mammals
Authors: ZAMMIT MARIA , KEAR BENJAMIN P. , NORRIS RACHEL M.
Published: November 2013

Reconstructing the swimming capabilities of extinct marine tetrapods is critical for unravelling broader questions about their palaeobiology, palaeoecology and palaeobiogeography. Ichthyosaurs have long been the subject of such investigations because, alongside cetaceans, they are one of the few tetrapod lineages to achieve a highly specialized fish-like body plan. The dominant locomotory mode for the majority of derived, post-Triassic ichthyosaurs is hypothesized to have been caudal fin-driven propulsion. Limb-based swimming has however been suggested for some highly autapomorphic forms, such as the Cretaceous genusPlatypterygius, which has a remarkably robust humeral morphology and exceptionally broad paddle-like limbs. To evaluate this atypical lifestyle model, we conducted a comprehensive comparative osteological assessment ofPlatypterygiusin relation to extant marine mammals, whose analogous skeletal frameworks provide a structurally compatible selection of alternate propulsive strategies. Based on a proxy exemplar of the most completely known species,P. australisfrom the Early Cretaceous of Australia, the propodial shape, absence of functional elbow/knee joints, tightly interlocking carpals, hyperphalangy and extreme reduction of the pelvic girdle are most similar to cetaceans as opposed to pinnipeds or dugongs. There is no obvious structural consistency with aquatic mammals that use sustained forelimb-driven swimming. The exceptionally broad fore-paddle (a product of hyperdactyly) and extensive humeral muscle insertions might therefore have had a cetacean-like role in enhancing manoeuvrability and acceleration performance. We conclude that, despite its atypical features,P. australiswas most likely similar to other ichthyosaurs in using lateral sweeps of the tailfin to generate primary propulsive thrust.
Iron deficiency during pregnancy: the consequences for placental function and fetal outcome
Authors: McArdle Harry J. , Gambling Lorraine , Kennedy Christine
Published: November 2013

This review examines the importance of the placenta in iron metabolism during development and the effect of iron deficiency on maternal and fetal physiology. Iron is an essential micronutrient, required for a wide variety of biological processes. During pregnancy, the mother has to deplete her iron stores in order to provide the baby with adequate amounts. Trans-placental iron transfer involves binding transferrin (Tf)-bound iron to the Tf receptor, uptake into an endosome, acidification, release of iron through divalent metal transporter 1, efflux across the basolateral membrane through ferroportin and oxidation of Fe(II) by zyklopen. An additional haem transport system has been hypothesised, which may explain why certain gene knockouts are not lethal for the developing fetus. Iron deficiency is a common phenomenon during pregnancy, and the placenta adapts by up-regulating its transfer systems, maintaining iron at the expense of the mother. Despite these adaptations, deficiency cannot be completely prevented, and the offspring suffers both short- and long-term consequences. Some of these, at least, may arise from decreased expression of genes involved in the cell cycle and altered expression of transcription factors, such as c-myc, which in turn can produce, for example, kidneys with reduced numbers of nephrons. The mechanism whereby these changes are induced is not certain, but may simply be as a result of the reduced availability of iron resulting in decreased enzyme activity. Since these changes are so significant, and because some of the changes are irreversible, we believe that iron prophylaxis should be considered in all pregnancies.
Local cortical thinning links to resting-state disconnectivity in major depressive disorder
Authors: van Tol M.-J. , Li M. , Metzger C. D. , Hailla N. , Horn D. I. , Li W. , Heinze H. J. , Bogerts B. , Steiner J. , He H. , Walter M.
Published: November 2013

Background

Local structural and metabolic as well as inter-regional connectivity abnormalities have been implicated in the neuropathology of major depressive disorder (MDD). How local tissue properties affect intrinsic functional connectivity is, however, unclear. Using a cross-sectional, multi-modal imaging approach, we investigated the relationship between local cortical tissue abnormalities and intrinsic resting-state functional connectivity (RSFC) in MDD.

Method

A total of 20 MDD in-patients and 20 healthy controls underwent magnetic resonance imaging at 3 T for structural and functional imaging. Whole-brain cortical thickness was calculated and compared between groups. Regions with reduced cortical thickness defined seeds for subsequent whole-brain RSFC analyses. Contributions of structural tissue abnormalities on inter-regional RSFC were explicitly investigated.

Results

Lower cortical thickness was observed in MDD in the right dorsomedial prefrontal cortex (PFC), superior temporal gyrus/temporal pole, middle-posterior cingulate cortex, and dorsolateral PFC. No differences in local fractional amplitude of low-frequency fluctuations were observed. Lower thickness in patients' dorsomedial PFC further directly and selectively affected its RSFC with the precuneus, which was unaffected by symptom severity. No effects of cortical thickness in other regions showing abnormal thickness were observed to influence functional connectivity.

Conclusions

Abnormal cortical thickness in the dorsomedial PFC in MDD patients was observed to selectively and directly affect its intrinsic connectivity with the precuneus in MDD patients independent of depression severity, thereby marking a potential vulnerability for maladaptive mood regulation. Future studies should include an unmedicated sample and replicate findings using independent component analysis to test for morphometric effects on network integrity.
Pharmacological, experimental therapeutic, and transcranial magnetic stimulation treatments for compulsivity and impulsivity
Authors: Pallanti Stefano , Hollander Eric
Published: November 2013

Obsessive-compulsive disorder (OCD) has been recently drawn apart from anxiety disorder by the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) and clustered together with related disorders (eg, hoarding, hair pulling disorder, skin picking), which with it seems to share clinical and neurophysiological similarities. Recent literature has mainly explored brain circuitries (eg, orbitofrontal cortex, striatum), molecular pathways, and genes (eg, Hoxb8, Slitrk5, Sapap3) that represent the new target of the treatments; they also lead the development of new probes and compounds. In the therapeutic field, monotherapy with cognitive behavioral therapy (CBT) or selective serotonin reuptake inhibitors (SSRIs) is recommendable, but combination or augmentation with a dopaminergic or glutamatergic agent is often adopted. A promising therapy for OCD is represented by repetitive transcranial magnetic stimulation (rTMS), which is suitable to treat compulsivity and impulsivity depending on the protocol of stimulation and the brain circuitries targeted.
Hypochondriasis and obsessive-compulsive disorder in schizophrenic patients treated with clozapine vs other atypical antipsychotics
Authors: Grassi Giacomo , Poli Lorenzo , Cantisani Andrea , Righi Lorenzo , Ferrari Gabriella , Pallanti Stefano
Published: November 2013

Objective

The aim of the study was to investigate the prevalence rates of obsessive-compulsive disorder (OCD) and hypochondriasis in schizophrenic patients treated with atypical antipsychotics (AAPs) and to investigate the different comorbidity rates of OCD and hypochondriasis between clozapine-treated patients and patients treated with other AAPs.

Methods

We therefore recruited 60 schizophrenic patients treated with clozapine or other AAPs. We assessed the prevalence rates of OCD or OC symptoms and hypochondriasis or hypochondriac symptoms in the whole group of patients and in clozapine-treated patients versus patients treated with other AAPs.

Results

Schizophrenic patients had a higher comorbidity rate of OCD (26.6% vs 1–3%) and hypochondriasis (20% vs 1%) than the general population. These comorbidities were more frequent in schizophrenic patients treated with clozapine versus patients treated with other AAPs (36.7% vs 16.7% and 33.3% vs 6.7%). Clozapine-treated patients showed a higher mean Y-BOCS and HY-BOCS score when compared to patients treated with other AAPs (10.90 vs 5.90, p = .099; 15.40 vs 8.93, p = .166). A statistical significant correlation was found between the Y-BOCS and HY-BOCS scores of the whole group (r = .378, p = 0.03). Furthermore, we found an inverse correlation between the global level of functioning and the diagnosis of hypochondriasis (p = .048) and the severity of hypochondriac symptoms (p = .047).

Conclusions

Hypochondriasis could represent an important clinical feature of schizophrenic patients treated with atypical antipsychotics, and further research is needed in this field.
Organic management and legume presence maintained phosphorus bioavailability in a 17-year field crop experiment
Authors: Gallaher Courtney , Snapp Sieglinde S.
Published: October 2013

Legumes have been shown to enhance bioavailability of phosphorus (P) from sparingly soluble pools, yet this functional trait remains underutilized in agriculture, and is untested at decadal scales. Management and legume presence effects on temporal soil properties were evaluated in a 17-year field crop experiment using soil samples collected in 1992, 2000 and 2006. Management systems compared included: (1) conventional corn–soybean–wheat rotation (C–S–W), (2) organic (C–S–W+red clover), (3) alfalfa and (4) early successional field. To evaluate the effects of long-term management versus recent management (residues and P fertilizer) on P and bio-availability to soybean, subplots of soybean were established with and without P-fertilizer (30 kg P ha−1), and compared to subplots and main plot with the long-term system. We evaluated soil properties (C, total P, Bray extractable inorganic P, particulate organic matter phosphorus) and soybean P uptake, biomass and yield. Recent fertilizer P inputs had no detectable influence on soil P, and total soil P stayed stable at ~350 mg P kg−1, whereas inorganic P (Pi) declined from an initial value of 54 to an average of 35 mg P kg−1. A P balance was constructed and showed a net loss of −96.7 kg P ha−1 yr−1 for the organic system, yet Bray-Pi and soybean P uptake were maintained under organic production at similar levels to the conventional, fertilized system. Particulate organic matter P was 57, 82 and 128% higher in organic, alfalfa and successional treatments, respectively, compared to conventional. A similar pattern was observed for soil C, soybean yield and bioavailable P, which were 20–50% higher in the organic, alfalfa and successional systems relative to conventional. This study provides evidence that long-term management history influences bioavailability of P.
The Religion of the Nonreligious and the Politics of the Apolitical: The Transformation of Falun Gong from Healing Practice to Political Movement
Authors: Li Junpeng
Published: November 2013

This article applies the conflict-amplification model to the development of Falun Gong. Falun Gong emerged in the early 1990s as a health-enhancing practice and part of the state-sanctionedqigongmovement in China. Faced with increasing state suspicion ofqigongand fierce competition from other groups, it metamorphosed into a new religious movement in the mid-1990s. State efforts to keep Falun Gong out of the political realm had the effect of releasing the group's political potential and led to its campaign of “truth clarification,” which further alerted the state to its ideological challenge and capacity to mobilize. Through a process of mutual feedback, the antagonism between the two parties culminated in religious violence and in Falun Gong's transformation into a political movement. The organizational evolution of Falun Gong is an illustration of the religion of the nonreligious and the politics of the apolitical in an authoritarian state.
Building bridges across political divides: experiments on deliberative democracy in deeply divided Belgium
Authors: Caluwaerts Didier , Deschouwer Kris
Published: November 2013

In recent years, deliberative democracy has moved from a philosophical ideal into an empirical theory with numerous experiments testing the theoretical assumptions. Despite the wealth of evidence on the potential for deliberation, scholars have remained hesitant to test the theoretical premises under rather more adverse circumstances. This article, in contrast, tries to push deliberative scholarship to its edge by focusing on the viability of citizen deliberation in deeply divided societies. Our research questions are whether contact between citizens of competing segments undermines the potential for deliberation, and under which institutional conditions this is so. Based on a deliberative experiment in Belgium, in which we varied the group composition and the decision-making rule, we argue that decision rules are strong predictors of deliberative quality, but more importantly that the confrontation between citizens from both sides of the divide does not undermine the quality of deliberation. On the contrary even, our results indicate that the quality of intergroup deliberation is higher than that of intragroup deliberation, no matter what the rule.
Testing Measurement Invariance in Media Psychological Research
Authors: Kühne Rinaldo
Published: November 2013

Media psychology increasingly focuses on comparative research questions by comparing media use and media effects across different populations and across time. Such comparisons require that the constructs of interest be measured in the same way across populations – that is, invariant measures are required. However, this methodological issue has rarely been addressed in media psychology. In this article, we explain the concept of measurement invariance and illustrate how measurement invariance can be established to compare media use and media effects across populations and over time.
Toward an Integration of the Learning and Communication Perspectives in Computer-Supported Instructional Communication
Authors: Deiglmayr Anne , Paus Elisabeth , McCall Cade , Mullins Dejana , Berthold Kirsten , Wittwer Jörg , Krämer Nicole , Rummel Nikol
Published: November 2013

Research on computer-supported instructional communication (CSIC) involves the study of interactions between instructors, learners, and system components in computer-based learning environments. At least two strands of research can be identified that are crucial for the understanding of CSIC: From the learning perspective, rooted in cognitive and educational psychology, CSIC is analyzed with regard to its potential for promoting specific cognitive processes, and thus ultimately for improving learning. From the communication perspective, rooted in social psychology and communication science, CSIC is analyzed with regard to conditions that affect its effectiveness and efficiency. CSIC researchers face the challenge of integrating the two traditionally separate research strands and their distinct methodological frameworks. In turn, new methods and findings emerging from an integrative application of research methods are leading to new conceptual challenges regarding the causal mechanisms mediating between the interindividual and the intraindividual levels in CSIC. We provide examples of CSIC research that demonstrate successful methodological integration, and introduce open conceptual challenges.
Helping Behaviors During Video Game Play
Authors: Velez John A. , Ewoldsen David R.
Published: November 2013

Research suggests that video games are becoming a social activity. Previous research has neglected the complicated social context in which people now play video games. However, a growing body of literature suggests that playing violent video games cooperatively with others can attenuate their aggression-facilitating effects and increase prosocial behaviors between players. To better understand which types of social game play can foster helping behaviors between players and which players may be engaging in these helping behaviors during game play, the current study administered a survey to 252 students who self-identified as video game players. The results suggest that participants who reported playing cooperatively/competitively with other players were more likely to report engaging in helping behaviors during game play. Additionally, participants who reported being motivated to play specialized roles in group game play and have an altruistic personality were more likely to report engaging in helping behaviors during game play.
Thirteen follies and fallacies about alternative medicine
Authors: Ernst Edzard
Published: November 2013

Thirteen common misunderstandings about alternative medicine and the consequences for health.
Microevolution of Renibacterium salmoninarum: evidence for intercontinental dissemination associated with fish movements
Authors: Brynildsrud Ola , Feil Edward J , Bohlin Jon , Castillo-Ramirez Santiago , Colquhoun Duncan , McCarthy Una , Matejusova Iveta M , Rhodes Linda D , Wiens Gregory D , Verner-Jeffreys David W
Published: October 2013

Renibacterium salmoninarum is the causative agent of bacterial kidney disease, a major pathogen of salmonid fish species worldwide. Very low levels of intra-species genetic diversity have hampered efforts to understand the transmission dynamics and recent evolutionary history of this Gram-positive bacterium. We exploited recent advances in the next-generation sequencing technology to generate genome-wide single-nucleotide polymorphism (SNP) data from 68 diverse R. salmoninarum isolates representing broad geographical and temporal ranges and different host species. Phylogenetic analysis robustly delineated two lineages (lineage 1 and lineage 2); futhermore, dating analysis estimated that the time to the most recent ancestor of all the isolates is 1239 years ago (95% credible interval (CI) 444–2720 years ago). Our data reveal the intercontinental spread of lineage 1 over the last century, concurrent with anthropogenic movement of live fish, feed and ova for aquaculture purposes and stocking of recreational fisheries, whilst lineage 2 appears to have been endemic in wild Eastern Atlantic salmonid stocks before commercial activity. The high resolution of the SNP-based analyses allowed us to separate closely related isolates linked to neighboring fish farms, indicating that they formed part of single outbreaks. We were able to demonstrate that the main lineage 1 subgroup of R. salmoninarum isolated from Norway and the UK likely represent an introduction to these areas ∼40 years ago. This study demonstrates the promise of this technology for analysis of micro and medium scale evolutionary relationships in veterinary and environmental microorganisms, as well as human pathogens.
Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot
Authors: Weiss K. M. , Miguel-Sanchez J. , Elzerman J. M.
Published: November 2013

A pair of self-assembled InGaAs quantum dots filled with two electrons can act as a singlet-triplet spin qubit that is robust against nuclear spin fluctuations as well as charge noise. This results in a T2* coherence time two orders of magnitude longer than that of a single electron, provided the qubit is operated at a particular “sweet spot” in gate voltage. However, at this fixed operating point the ground-state splitting can no longer be tuned into resonance with e.g. another qubit, limiting the options for coupling multiple qubits. Here, we propose using a four-electron coupled quantum dot to implement a singlet-triplet qubit that features a magnetically tunable level splitting. As a first step towards full experimental realization of this qubit design, we use optical spectroscopy to demonstrate the tunability of the four-electron singlet-triplet splitting in a moderate magnetic field.
Double‐sided permanent‐magnet radial‐flux eddy‐current couplers: three‐dimensional analytical modelling, static and transient study, and sensitivity analysis
Authors: Mohammadi Sajjad , Mirsalim Mojtaba
Published: October 2013

Analytical models are widely utilised in the study and performance prediction of electric machines by providing fast, yet accurate solutions. By combining conventional magnetic equivalent circuit techniques with Faraday's and Ampere's laws, an analytical model for double‐sided permanent‐magnet radial‐flux eddy‐current couplers is presented that can easily handle complex geometries. The proposed approach is also capable of taking the three‐dimensional (3D) impacts into account. The characteristics and design considerations are also studied for a surface‐mounted permanent‐magnet structure. Moreover, the 2D and 3D finite‐element methods are employed to verify the results, as well as transient study of the device under two different scenarios. Finally, sensitivity analysis is carried out to investigate the influence of the design variables on the characteristics of the coupler, which provides valuable information in the current and future studies of such devices.
Modified current‐fed full‐bridge isolated power factor correction converter with low‐voltage stress
Authors: Trong Nha Quang , Chiu Huang‐Jen , Lo Yu‐Kang , Lin Chin‐Yu , Alam Mohammed Mahmood
Published: October 2013

One drawback of the conventional current‐fed full‐bridge (CFFB) power factor correction (PFC) converters is extremely high‐voltage spikes on metal oxide semiconductor field effect transistors (MOSFETs), which cause many problems such as high‐voltage high‐cost devices used, unreliability and burdensome magnetising components imposed. To overcome above shortcomings, a new isolated CFFB PFC converter featuring efficiency improvement, high input current quality and good common mode (CM) noise performance is proposed in this study. The voltage spikes are effectively eliminated by using a non‐dissipative clamping structure resulting of no‐loss consumption and low‐voltage MOSFETs used. Additionally, to evaluate the conducted electromagnetic interference behaviour, the differential mode loop and CM loop models are also presented. Two testing hardware systems with 180–240 V input, 380 V/1 kW output of the conventional CFFB PFC and proposed PFC were built and inspected to compare their performances. The experimental results showed that the proposed topology completely eliminated the voltage spike on MOSFETs. The efficiency was largely improved by utilising of high‐performance MOSFETs. In consequence, the experimental results reveal the preponderance of the proposed PFC converter to the previous researches on this topic.
Single transceiver‐based time division multiplexing multiple‐input–multiple‐output digital beamforming radar system: concepts and experiments
Authors: Tang Yue , Lu Yilong
Published: October 2013

This study presents a time division multiplexing (TDM) multiple‐input–multiple‐output (MIMO) digital beamforming (DBF) radar concept based on a single transceiver (one transmitter and one receiver). Compared with a conventional MIMO DBF radar system with M‐element transmitting array and N‐element receiving array, the proposed concept can reduce the number of transmitter/receivers from M + N to 2 for a drastic cost reduction. In addition to theoretical analysis and numerical simulation, an experimental TDM MIMO DBF radar demonstrator is realised and tested for verification using real data. Numerical analysis and experimental results show that the proposed concept can achieve considerable higher angular resolution at lower cost compared to conventional DBF radar concepts using the same antenna array with one‐way or two‐way beamforming.
Composition induced structure evolution and large strain response in ternary Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-SrTiO3 solid solution
Authors: Wang Feifei , Ming Leung Chung , Tang Yanxue , Wang Tao , Shi Wangzhou
Published: October 2013

A ternary perovskite lead-free solid solution Bi0.5Na0.5TiO3-Bi0.5K0.5TiO3-SrTiO3 was designed and fabricated using a conventional fabrication process. The temperature and composition dependence of the ferroelectric, dielectric, piezoelectric, and electromechanical properties were systematically investigated, and a schematic phase diagram was established. The introduction of the SrTiO3 was found to induce a structure evolution from the ferroelectric rhombohedra to ergodic relaxor pseudocubic phases. At a critical composition with SrTiO3 of 0.15, large strain level of ∼0.25% was obtained under a moderate field of 4.4 kV/mm at 0.1 Hz and the normalized strain reached up to 585 pm/V. Through the combination of the X-ray diffraction results with the piezoresponse force microscopy analysis, the composition induced structure evolution process and intrinsic mechanism responsible for the large strain response were discussed. The large strain level also makes the system quite promising for application to “on-off” actuators.
Dipolar Poisson-Boltzmann approach to ionic solutions: A mean field and loop expansion analysis
Authors: Levy Amir , Andelman David , Orland Henri
Published: November 2013

We study the variation of the dielectric response of ionic aqueous solutions as function of their ionic strength. The effect of salt on the dielectric constant appears through the coupling between ions and dipolar water molecules. On a mean-field level, we account for any internal charge distribution of particles. The dipolar degrees of freedom are added to the ionic ones and result in a generalization of the Poisson-Boltzmann (PB) equation called the Dipolar PB (DPB). By looking at the DPB equation around a fixed point-like ion, a closed-form formula for the dielectric constant is obtained. We express the dielectric constant using the “hydration length” that characterizes the hydration shell of dipoles around ions, and thus the strength of the dielectric decrement. The DPB equation is then examined for three additional cases: mixture of solvents, polarizable medium, and ions of finite size. Employing field-theoretical methods, we expand the Gibbs free-energy to first order in a loop expansion and calculate self-consistently the dielectric constant. For pure water, the dipolar fluctuations represent an important correction to the mean-field value and good agreement with the water dielectric constant is obtained. For ionic solutions we predict analytically the dielectric decrement that depends on the ionic strength in a nonlinear way. Our prediction fits rather well a large range of concentrations for different salts using only one fit parameter related to the size of ions and dipoles. A linear dependence of the dielectric constant on the salt concentration is observed at low salinity, and a noticeable deviation from linearity can be seen for ionic strength above 1 M, in agreement with experiments.
High-pressure polyol synthesis of ultrathin silver nanowires: Electrical and optical properties
Authors: Lee Eun-Jong , Chang Min-Hwa , Kim Youn-Soo , Kim Jin-Yeol
Published: November 2013

Silver nanowires whose diameters could be controlled in the range of 15–30 nm and lengths up to ∼20 μm were prepared by the high-pressure polyol method. The first step involved the formation of Ag nanoparticles by reducing silver nitrate in the presence of NaCl and KBr with ethylene glycol. At the growing step, the adjustable reaction pressure controls the diameter of the silver nanowires, which were in the range 15–22 nm when the pressure was 200 psi. These Ag nanowires showed an electrical conductivity of 0.4 × 105 S/cm, and the intensity of scattered light and the optical transmittance were largely improved.
Increasing the efficiency of a thermionic engine using a negative electron affinity collector
Authors: Ryan Smith Joshua
Published: November 2013

Most attention to improving vacuum thermionic energy conversion device (TEC) technology has been on improving electron emission with little attention to collector optimization. A model was developed to characterize the output characteristics of a TEC where the collector features negative electron affinity. According to the model, there are certain conditions for which the space charge limitation can be reduced or eliminated. The model is applied to devices comprised materials reported in the literature, and predictions of output power and efficiency are made, targeting the sub-1000 K hot-side regime. By slightly lowering the collector barrier height, an output power of around 1 kW, at ≥20% efficiency for a reasonably sized device (∼0.1 m2 emission area) can be achieved.
Micro-/macro-responses of a ferroelectric single crystal with domain pinning and depinning by dislocations
Authors: Wu H. H. , Wang J. , Cao S. G. , Chen L. Q. , Zhang T. Y.
Published: October 2013

Phase field simulations are conducted to investigate the micro-structural signature and the macro-response of a ferroelectric single crystal with domain pinning and depinning phenomena by dislocation arrays. It is shown that due to the presence of the dislocation arrays, a domain with polarizations antiparallel to an applied field can survive under the small amplitude of applied field. The residual domain serves as a pre-existing nucleus during the following macroscopic switching via only domain wall motion. The pinned domain will be depinned when the external electric field amplitude exceeds a critical value, which highly depends on the dislocation spacing in the dislocation array. Due to the pinning and depinning effect, an asymmetric hysteresis loop of polarization versus electric field might appear when a bias field is applied.
New insights into designing metallacarborane based room temperature hydrogen storage media
Authors: Bora Pankaj Lochan , Singh Abhishek K.
Published: November 2013

Metallacarboranes are promising towards realizing room temperature hydrogen storage media because of the presence of both transition metal and carbon atoms. In metallacarborane clusters, the transition metal adsorbs hydrogen molecules and carbon can link these clusters to form metal organic framework, which can serve as a complete storage medium. Using first principles density functional calculations, we chalk out the underlying principles of designing an efficient metallacarborane based hydrogen storage media. The storage capacity of hydrogen depends upon the number of available transition metal d-orbitals, number of carbons, and dopant atoms in the cluster. These factors control the amount of charge transfer from metal to the cluster, thereby affecting the number of adsorbed hydrogen molecules. This correlation between the charge transfer and storage capacity is general in nature, and can be applied to designing efficient hydrogen storage systems. Following this strategy, a search for the best metallacarborane was carried out in which Sc based monocarborane was found to be the most promising H2 sorbent material with a 9 wt.% of reversible storage at ambient pressure and temperature.
Gas feeding molecular phosphorous ion source for semiconductor implanters
Authors: Gushenets V. I. , Oks E. M. , Bugaev A. S. , Kulevoy T. V. , Hershcovitch A.
Published: October 2013

Phosphorus is a much used dopant in semiconductor technology. Its vapors represent a rather stable tetratomic molecular compound and are produced from one of the most thermodynamically stable allotropic forms of phosphorus—red phosphorus. At vacuum heating temperatures ranging from 325 °C, red phosphorus evaporates solely as P4 molecules (P4/P2 ∼ 2 × 105, P4/P ∼ 1021). It is for this reason that red phosphorus is best suited as a source of polyatomic molecular ion beams. The paper reports on experimental research in the generation of polyatomic phosphorus ion beams with an alternative P vapor source for which a gaseous compound of phosphorus with hydrogen – phosphine – is used. The ion source is equipped with a specially designed dissociator in which phosphine heated to temperatures close to 700 °C decomposes into molecular hydrogen and phosphorus (P4) and then the reaction products are delivered through a vapor line to the discharge chamber. Experimental data are presented reflecting the influence of the discharge parameters and temperature of the dissociator heater on the mass-charge state of the ion beam.
Cause of the fragile-to-strong transition observed in water confined in C-S-H gel
Authors: Monasterio Manuel , Jansson Helén , Gaitero Juan J. , Dolado Jorge S. , Cerveny Silvina
Published: November 2013

In this study, the rotational dynamics of hydration water confined in calcium-silicate-hydrate (C-S-H) gel with a water content of 22 wt.% was studied by broadband dielectric spectroscopy in broad temperature (110–300 K) and frequency (10−1–108 Hz) ranges. The C-S-H gel was used as a 3D confining system for investigating the possible existence of a fragile-to-strong transition for water around 220 K. Such transition was observed at 220 K in a previous study [Y. Zhang, M. Lagi, F. Ridi, E. Fratini, P. Baglioni, E. Mamontov and S. H. Chen, J. Phys.: Condens. Matter 20, 502101 (2008)] on a similar system, and it was there associated with a hidden critical point of bulk water. However, based on the experimental results presented here, there is no sign of a fragile-to-strong transition for water confined in C-S-H gel. Instead, the fragile-to-strong transition can be explained by a merging of two different relaxation processes at about 220 K.
Development of microwave ion source for industrial applications
Authors: Takahashi N. , Murata H. , Mitsubori H. , Sakuraba J. , Soga T. , Aoki Y. , Katoh T. , Saitoh Y. , Yamada K. , Ikenaga N. , Sakudo N.
Published: November 2013

A microwave ion source is one of the long-life ion sources. In this paper, we report on the characteristics of the extracted Ar ion beam produced by a microwave ion source under various conditions, in terms of magnetic flux distribution and mass flow, and the stability of the ion beam. The measured spectra show that, under the experimental condition, almost all of produced ions were Ar+ ions. For more than 6 h, the ion beam was stable.
Myths and verities in protein folding theories: From Frank and Evans iceberg-conjecture to explanation of the hydrophobic effect
Authors: Ben-Naim Arieh
Published: November 2013

Starting from the seminal article by Frank and Evans where the “iceberg formation” idea was first expressed, we follow the evolution of this idea to the explanation of the hydrophobic effect. We show that the idea of iceberg formation can provide an explanation to the entropy, and enthalpy of solvation of non-polar solutes in water, provided one first explains why a simple non-polar solute would form icebergs in the first place. Having done that, the questions regarding the outstanding large hydrophobic solvation Gibbs energy remains unexplained. This conclusion follows from the exact entropy-enthalpy-compensation pertaining to any structural changes induced in the solvent. We also comment on some misinterpretation of the partial molar heat capacity of non-polar solutes in water.
Immobilization of [60]fullerene on silicon surfaces through a calix[8]arene layer
Authors: Busolo Filippo , Silvestrini Simone , Armelao Lidia , Maggini Michele
Published: November 2013

In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.
Quasi-analytic study of scattering from optical plasmonic patch antennas
Authors: Ciracì Cristian , Britt Lassiter J. , Moreau Antoine , Smith David R.
Published: November 2013

We present an analytical treatment of the optical scattering from film-coupled nanocubes. Film-coupled nanoparticles are a convenient platform for the demonstration of a variety of fundamental plasmonic phenomena, including nonlocality and field enhancement, and can also serve as the basis for controlled reflectance surfaces. The nanocube geometry is particularly amenable to analysis, since the cubes behave in large part as plasmon resonant patch antennas, allowing the well-known patch antenna equations to be applied with some modifications. In particular, we make use of the plasmon dispersion relation to avoid direct calculation of the effective inductance per unit length—which would include kinetic inductance contributions—instead calculating the effective waveguide mode index to incorporate plasmonic contributions. We compare the analytically derived field enhancement and spectral characteristics of the film-coupled nanoparticles with those obtained from full-wave finite-element simulations.
Thermal conductivity measurements on individual vapor-grown carbon nanofibers and graphene nanoplatelets
Authors: Mahanta Nayandeep K. , Abramson Alexis R. , Howe Jane Y.
Published: November 2013

The thermal flash technique was utilized for measuring the thermal conductivity of vapor-grown carbon nanofibers and graphene nanoplatelets. The vapor-grown carbon nanofibers with stacked-cone morphology and heat treated to 1100 °C and 3000 °C were measured to have thermal conductivities of 1130 W/m K and 1715 W/m K, respectively. The physical dimensions of the constitutive cones determining the mean free path due to static phonon scattering were estimated to be ∼128 nm and ∼176 nm for the low and high heat treatment temperatures, respectively. Static scattering lengths shorter than the Umklapp scattering length indicate ballistic transport within individual cones and limit the thermal conductivities of the nanofibers. Additionally, nanoplatelets of few-layer oxygen intercalated graphene and multi-layer reduced graphene exhibited thermal conductivities of 776 W/m K and 2275 W/m K, respectively. The lower thermal conductivity of few-layer (∼3 layers) graphene is attributed to the presence of intercalating oxygen atoms which introduce covalent character to the interlayer interactions, acting as phonon scattering centers and hence reducing the phonon mean free path. The thermal conductivity measured for multi-layer graphene with ∼30–45 layers lies within range of the thermal conductivities previously reported for bulk graphite.
Comparative study of label-free electrochemical immunoassay on various gold nanostructures
Authors: Rafique S. , Gao C. , Li C. M. , Bhatti A. S.
Published: November 2013

Electrochemical methods such as amperometry and impedance spectroscopy provide the feasibility of label-free immunoassay. However, the performance of electrochemical interfaces varies with the shape of gold nanostructures. In the present work three types of gold nanostructures including pyramid, spherical, and rod-like nanostructures were electrochemically synthesized on the gold electrode and were further transformed into immunosensor by covalent binding of antibodies. As a model protein, a cancer biomarker, Carcinoembryonic Antigen (CEA) was detected using amperometric and impedimetric techniques on three nanostructured electrodes, which enabled to evaluate and compare the immunoassay's performance. It was found that all three immunosensors showed improved linear electrochemical response to the concentration of CEA compared to bare Au electrode. Among all the spherical gold nanostructure based immunosensors displayed superior performance. Under optimal condition, the immunosensors exhibited a limit of detection of 4.1 pg ml−1 over a concentration range of five orders of magnitude. This paper emphasizes that fine control over the geometry of nanostructures is essentially important for high-performance electrochemical immunoassay.
From the circular cylinder to the flat plate wake: The variation of Strouhal number with Reynolds number for elliptical cylinders
Authors: Radi Alexander , Thompson Mark C. , Sheridan John , Hourigan Kerry
Published: October 2013

The variation of Strouhal number with Reynolds number is quantified experimentally for a series of elliptical cylinders spanning aspect ratios between \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ar}}=1$\end{document}Ar=1, corresponding to a circular cylinder, and \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ar}}=0$\end{document}Ar=0, corresponding to a flat plate, over the Reynolds number range \documentclass[12pt]{minimal}\begin{document}$100 \leqslant \mbox{\textit {Re}}\leqslant 300$\end{document}100⩽Re⩽300. The widths of the spectral peaks in Fourier space at each Reynolds number, together with changes in the shape or continuity of the Strouhal number curves, provide information of underlying three-dimensional transitions. Whilst modified versions of the mode A and B transitions of a circular cylinder wake occur at aspect ratios above \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ar}}\approx 0.4$\end{document}Ar≈0.4, one major difference is observed for \documentclass[12pt]{minimal}\begin{document}$\mbox{\textit {Ar}}\lesssim 0.4$\end{document}Ar≲0.4. In a limited range of Reynolds numbers, the wake appears to re-laminarize after it has already undergone three-dimensional transition. This flow regime is characterized by a strictly periodic vortex shedding.
The Aharonov-Bohm effect with a twist: Electron transport through finite-width Möbius rings
Authors: Li Zehao , Ram-Mohan L. R.
Published: November 2013

The Aharonov-Bohm effect manifests itself in the interference of electron waves traveling through multiply-connected regions and the flux linked with the paths for the electron. Here, we consider the transmission of electrons in the presence of a magnetic field through a finite-width Möbius ring structure which displays a nontrivial topology. The results are compared with the transport through a flat annular ring and a cylindrical ring, with finite-width input and output contacts attached at the periphery in order to highlight the differences in the transmission and conductance patterns. We develop a model to account for the main features associated with the interference effects for propagating states on the Möbius ring. We demonstrate that the periodicity in the magnetic flux, in units of h/e, is weakly broken on 2D rings of finite width, so that the simple treatment proposed here is sufficient for interpreting results. The unusual states with half-integer values of ⟨Lz⟩ present on Möbius rings display a different characteristic in transmission. Such resonant states are in constructive interference for transmission at magnetic fields where the contribution from ordinary states with integer ⟨Lz⟩ is in destructive interference, and vice versa. This leads to an alternating dominance of the set of half-integer ⟨Lz⟩ states and the set of integer ⟨Lz⟩ states in transport with increasing magnetic fields. We calculate the conductance of the rings, using the Landauer-Büttiker formula, as a function of the magnetic field and the applied bias at contact reservoirs. The differences in the structures considered lend hope for possible for magnetic sensor applications.
Enhanced thermoelectric performance in Bi-doped p-type AgSbTe2 compounds
Authors: Mohanraman Rajeshkumar , Sankar Raman , Chou F. C. , Lee C. H. , Chen Yang-Yuan
Published: November 2013

The influence of bismuth (Bi) substitution on the thermoelectric properties of AgSbTe2 compounds was investigated and compared with the undoped AgSbTe2. The addition of Bi dopants not only resulted in a reduction in thermal conductivity but also markedly increased the thermopower in the Ag(Sb1−xBix)Te2 series. Additional phonon scatterings were created by Bi doping and led to a reduction of thermal conductivity. The lattice thermal conductivity is significantly reduced which could be ascribed to enhancement of phonon scattering by dopants with greater atomic weight. In addition, the thermopower was enhanced, which was attributed to the electron-filtering effects caused by the nanoscaled microstructures. Because of the extremely low thermal conductivity (0.48 Wm−1K−1) and moderate power factor of AgBi0.05Sb0.95Te2, a maximum ZT value of (1.04 ± 0.08) was reached at 570 K; yielding an enhancement of greater than 10% compared with an undoped AgSbTe2. this result shows promising thermoelectric properties in the medium temperature range.
Graphene nanomesh transistor with high on/off ratio and good saturation behavior
Authors: Berrada Salim , Hung Nguyen Viet , Querlioz Damien , Saint-Martin Jérôme , Alarcón Alfonso , Chassat Christophe , Bournel Arnaud , Dollfus Philippe
Published: November 2013

We investigate the device operation and performance of transistors based on a graphene nanomesh lattice. By means of numerical simulation, we show that this device architecture allows suppressing the chiral tunneling, which reduces drastically the off current and enhances the on/off ratio compared to the pristine graphene counterpart. Additionally, a good saturation of current can be reached in the thermionic regime of transport. Though reduced compared to the case of pristine transistors, the transconductance and the cutoff frequency are still high. Above all, the nanomesh transistors outperform their pristine graphene counterpart in terms of voltage gain and maximum oscillation frequency.
Widely tunable thermo-optic plasmonic bandpass filter
Authors: Lee Jongwon , Belkin Mikhail A.
Published: October 2013

We report thermally tunable optical bandpass filters based on long-range surface plasmon polariton waveguides. A thin gold stripe in the waveguide core is surrounded by dielectric layers with dissimilar refractive index dispersions and dissimilar thermo-optic coefficients. High filter transmission is achieved for a wavelength at which the refractive indices of the upper and lower cladding layers are identical, and this spectral point may be changed by varying the filter temperature. Experimentally, over 220 nm of bandpass tuning is achieved around 1550 nm wavelength by varying the device temperature from 19 to 27 °C.