bluuebunny/crossref_metadata_2025 huggingface dataset:
SnO2 Nanoparticle‐Coated ZnO Nanotube Arrays for High‐Performance Electrochemical Sensors
Authors: She Guangwei , Huang Xing , Jin Liangliang , Qi Xiaopeng , Mu Lixuan , Shi Wensheng
Published: August 2014

Novel 1D nanostructures offer new opportunities for improving the performance of electrochemical sensors. In this study, highly ordered 1D nanostructure array electrodes composed of SnO2 nanoparticle‐coated ZnO (SnO2@ZnO) nanotubes are designed and fabricated. The composite nanotube array architecture not only endows the electrochemical electrodes with large surface areas, but also allows electrons to be quickly transferred along the nanotubes. Modifying the SnO2@ZnO nanotube arrays with negatively charged polymer film and employing them as a working electrode, sensitive and selective electrochemical detection of an important neurotransmitter, i.e., dopamine, is realized via the cycle voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Interference from ascorbic acid can be successfully eliminated. The oxidative peak currents recorded from CV linearly depend on the dopamine concentrations from 0.1 to 100 μM with a sensitivity of 2.16 × 10−7 A μM−1 cm−2 and detection limit of 45.2 nM. Using the DPV technique, an improved sensitivity and detection limit of 1.94 × 10−6 A μM−1 cm−2 and 17.7 nM are respectively achieved. Moreover, the SnO2@ZnO nanotube array electrodes can be reused through simple ultrasonical cleaning and no obvious deterioration is observed in the performance.
Myb Permits Multilineage Airway Epithelial Cell Differentiation
Authors: Pan Jie-Hong , Adair-Kirk Tracy L. , Patel Anand C. , Huang Tao , Yozamp Nicholas S. , Xu Jian , Reddy E. Premkumar , Byers Derek E. , Pierce Richard A. , Holtzman Michael J. , Brody Steven L.
Published: August 2014

The epithelium of the pulmonary airway is specially differentiated to provide defense against environmental insults, but also subject to dysregulated differentiation that results in lung disease. The current paradigm for airway epithelial differentiation is a one-step program whereby a p63+ basal epithelial progenitor cell generates a ciliated or secretory cell lineage, but the cue for this transition and whether there are intermediate steps are poorly defined. Here, we identify transcription factor Myb as a key regulator that permits early multilineage differentiation of airway epithelial cells. Myb+ cells were identified as p63− and therefore distinct from basal progenitor cells, but were still negative for markers of differentiation. Myb RNAi treatment of primary-culture airway epithelial cells and Myb gene deletion in mice resulted in a p63− population with failed maturation of Foxj1+ ciliated cells as well as Scbg1a1+ and Muc5ac+ secretory cells. Consistent with these findings, analysis of whole genome expression of Myb-deficient cells identified Myb-dependent programs for ciliated and secretory cell differentiation. Myb+ cells were rare in human airways but were increased in regions of ciliated cells and mucous cell hyperplasia in samples from subjects with chronic obstructive pulmonary disease. Together, the results show that a p63− Myb+ population of airway epithelial cells represents a distinct intermediate stage of differentiation that is required under normal conditions and may be heightened in airway disease. Stem Cells  2014;32:3245–3256
The carbonate fuel cell—concept to reality
Authors: Farooque M.
Published: August 2014

The high temperature carbonate fuel cell is an ultraclean and high efficiency power generator. Its operating temperature, ∼550–650°C, is considered optimum to facilitate fast reaction kinetics, utilize waste heat efficiently, and at the same time allow use of commercial commodity construction materials and well‐established manufacturing processes which permit cell construction in large sizes. Also, the carbonate fuel cell can be equipped with the unique capability to generate hydrogen within the fuel cell from a hydrocarbon fuel allowing a simpler power plant system design. Because of these favorable attributes, the carbonate fuel cell is leading commercial deployment for clean distributed power. The carbonate fuel cell power plants are currently available in the size ranges 350 kW, 1.4 MW, and 2.8 MW. These plants are installed at numerous locations worldwide and have delivered 2.0 GWh of ultraclean electricity (as of mid‐December, 2013). Carbonate fuel cell technology and product status is described in this article. WIREs Energy Environ 2015, 4:178–188. doi: 10.1002/wene.124

This article is categorized under:

Fuel Cells and Hydrogen > Science and Materials
Urolithiasis in a captive group of Tammar wallabies (Macropus eugenii)
Authors: Liptovszky Mátyás , Sós Endre , Bende Balázs , Perge Edina , Molnár Viktor
Published: August 2014

Urolithiasis is a well‐known disease of the urogenital system in domestic animals, and it has also been described in captive and free‐ranging wildlife. This article reports 15 cases of urolithiasis in a captive group of Tammar wallabies (Macropus eugenii) between 2004 and 2011. The analyzed stones were composed of pure calcium carbonate (n = 5), calcium carbonate with traces of calcium phosphate (n = 6), carbonate apatite (n = 2), and carbonate apatite mixed with calcium oxalate (n = 2). In 12 out of 15 cases uroliths were situated only in the renal pelvis; in two cases they were found in the renal pelvis and the ureter; while in one case in the ureter only. No common infectious agents were identified either by microbiological or histopathological methods. Although the exact cause remains unknown, the repetitive occurrence of calcium carbonate urolithiasis suggests husbandry‐related causes. To the best of the authors' knowledge, this is the first report on recurrent appearance of urolithiasis in a captive group of Tammar wallabies. Zoo Biol. 33:455–458, 2014. © 2014 Wiley Periodicals Inc.
Identification of candidate genes required for susceptibility to powdery or downy mildew in cucumber
Authors: Schouten Henk J. , Krauskopf Julian , Visser Richard G. F. , Bai Yuling
Published: August 2014

Powdery mildew (PM, caused by Podosphaera fusca) and downy mildew (DM, caused by Pseudoperonospora cubensis) are important diseases of cucumber (Cucumis sativus). Breeding for resistance has been undertaken since the 1940s, but underlying resistance genes have not been functionally analysed yet. The published genome sequence of cucumber catalyses the search for such genes. Genetic studies have indicated that resistances to PM and DM in cucumber are often inherited recessively, which indicates the presence of susceptibility genes (S-genes). Therefore we analyzed the cucumber genome for homologs of functionally proven S-genes known from other plant species. We identified 13 MLO-like genes in cucumber, three of which cluster in Clade V, the clade that contains all known MLO-like susceptibility genes to powdery mildews in other dicots. The expression of one of these three genes, CsaMLO1, located on chromosome 1, was upregulated after PM inoculation. It co-localizes with a QTL for PM resistance previously identified. Also homologs of the susceptibility genes PMR4 and PMR5 are located at this QTL. The second MLO-like gene from Clade V (CsaMLO8) resides in a recessively inherited major QTL for PM resistance at the bottom of chromosome 5, together with a PMR6-like gene. Two major QTL for DM recessive resistance at the top of chromosome 5 co-localize with CsaDMR6-2, which is homologous to the DMR6 susceptibility gene in Arabidopsis. This study has identified several candidate genes for susceptibility to PM and DM in cucumber that may explain QTL for recessively inherited resistance, reported earlier.
Single Leg Squat Test and Its Relationship to Dynamic Knee Valgus and Injury Risk Screening
Authors: Ugalde Viviane , Brockman Chuck , Bailowitz Zach , Pollard Christine D.
Published: August 2014

Background

Lower extremity injuries are common in athletes. Valid tests to assess for risk of injury that are easily performed during a preparticipation sports physical examination are lacking. Two‐dimensional (2D) analysis of the drop‐jump test can identify athletes at risk, but it is too expensive and cumbersome to use in this setting.

Objective

To identify if those who perform a “positive”(abnormal postures) single leg squat (SLS) test also exhibit greater “dynamic valgus” on the 2D drop‐jump test. Our secondary purpose was to assess whether group differences in gender, age, or body mass index are evident between those who exhibit a positive SLS test result versus a negative SLS test result. Also, we wanted to determine any gender differences with the 2D drop‐jump test.

Design

A cross‐sectional study.

Setting

Private practice, preparticipation sports physical examinations.

Participants

A total of 142 middle school and high school athletes.

Methods

Participants performed a SLS test and a drop‐jump test during their preparticipation sports physical examination. Individuals were partitioned into groups based on the outcome of their SLS test (positive SLS group versus negative SLS group). Independent sample t‐tests were used to evaluate SLS group differences in the drop‐jump test, age, and body mass index, and the χ2 test was used to evaluate SLS group differences in gender (P ≤ .05).

Main Outcome Measurements

The SLS test and drop‐jump test.

Results

Seventy‐three of the 142 athletes (51%) had a positive SLS test result, whereas 69 athletes (49%) had a negative SLS test result. Individuals in the positive SLS group had a significantly lower knee‐hip ratio), indicative of greater dynamic knee valgus, than did those in the negative SLS group (P = .02). Individual characteristics between SLS groups including gender, age, and body mass index were similar.

Conclusion

The SLS test is a reasonable tool to use in preparticipation sports physical examinations to assess for dynamic knee valgus and the potential risk of lower extremity injury.
Transient Osteoporosis of Pregnancy of the Bilateral Hips in Twin Gestation: A Case Series
Authors: Reese Maria E. , Fitzgerald Colleen , Hynes Christina
Published: August 2014

Transient osteoporosis of pregnancy has been described as a rare, self‐limiting disease of unclear etiology that presents as severe pain, which typically affects pregnant women in their third trimester. We describe 3 cases of primigravid pregnant women with twin gestation who reported unilateral hip pain and who were diagnosed with transient osteoporosis of pregnancy of the hip by magnetic resonance imaging. These women were advised to undergo limited weight bearing and activity modification to minimize the risk of fracture. Each patient was able to proceed through her pregnancy, delivery, and postpartum course without complication, with symptom resolution, and return to unrestricted activity.
A history of the Allais paradox
Authors: HEUKELOM FLORIS
Published: August 2014

This article documents the history of the Allais paradox, and shows that underneath the many discussions of the various protagonists lay different, irreconcilable epistemological positions. Savage, like his mentor von Neumann and similar to economist Friedman, worked from an epistemology of generalized characterizations. Allais, on the other hand, like economists Samuelson and Baumol, started from an epistemology of exact descriptions in which every axiom was an empirical claim that could be refuted directly by observations. As a result, the two sides failed to find a common ground. Only a few decades later was the now so-called Allais paradox rediscovered as an important precursor when a new behavioural economic subdiscipline started to adopt the epistemology of exact descriptions and its accompanying falsifications of rational choice theory.
New species of the scale worm genus Pholoides (Polychaeta: Sigalionidae) from south-east Brazil
Authors: Padovanni Nathalia , Amaral Antonia Cecília Zacagnini
Published: August 2014

A new species of scale worm, Pholoides brasiliensis sp. nov., belonging to the family Sigalionidae, has been found in Espírito Santo, Rio de Janeiro and São Paulo States, south-east Brazil. The new species is mainly characterized by a long papilla in the subdistal region of the neuropodia and a prominent papilla on the ventral side of the tentaculophore. Pholoides remains species-poor compared to most Sigalionidae genera, and currently comprises four species.
New Materialisms, discourse analysis, and International Relations: a radical intertextual approach
Authors: LUNDBORG TOM , VAUGHAN-WILLIAMS NICK
Published: August 2014

This article investigates the recent ‘New Materialisms’ turn in social and political thought and asks what the potential theoretical and methodological significance might be for the study of International Relations (IR). To do so we return to debates about the theoretical status of discourse in IR as it is in this context that the question of materiality – particularly as it relates to language – has featured prominently in recent years. While the concept of discourse is increasingly narrow in IR, the ‘New Materialisms’ literature emphasises the political force of materiality beyond language and representation. However, a move to reprioritise the politics of materiality over that of language and representation is equally problematic since it perpetuates rather than challenges the notion of a prior distinction between language and materiality. In response, we draw on earlier poststructural thought in order to displace this dichotomy and articulate an extended understanding of what analysing ‘discourse’ might mean in the study of IR.
Arguing with law: strategic legal argumentation, US diplomacy, and debates over the International Criminal Court
Authors: BOWER ADAM
Published: August 2014

Recent studies have highlighted the instrumental use of language, wherein actors deploy claims to strategically pursue policy goals in the absence of persuasion or socialisation. Yet these accounts are insufficiently attentive to the social context in which an audience assesses and responds to strategic appeals. I present a theoretical account that highlights the distinctly powerful role of international law in framing strategic argumentation. Legalised discourses are especially legitimate because law is premised on a set of internally coherent practices that constitute actors and forms of action. I then illustrate the implications in a hard case concerning US efforts to secure immunities from International Criminal Court jurisdiction. Contrary to realist accounts of law as a tool of the powerful, I show that both pro- and anti-ICC diplomacy was channelled through a legal lens that imposed substantial constraints on the pursuit of policy objectives. Court proponents responded to US diplomatic pressure with their own legal arguments; this narrowed the scope of the exemptions, even as the Security Council temporarily conceded to US demands. While the US sought to marry coercion with argumentative appeals, it failed to generate a lasting change in global practice concerning ICC jurisdiction.
Representation of Women in the Parliament of the Weimar Republic: Evidence from Roll Call Votes
Authors: Debus Marc , Hansen Martin Ejnar
Published: August 2014

In modern democracies, the representation of voter interests and preferences is primarily the job of political parties and their elected officials. These patterns can, however, change when the issues that are at stake concern the interests of social groups represented by all relevant parties of a political system. In this article we focus on the behavior of female MPs in the parliament of Weimar Germany and, thus, on a parliament where legislative party discipline was very high. On the basis of a dataset containing information on the legislative voting behavior of MPs, we show that gender, even when controlling for a battery of further theoretically derived explanatory factors, had a decisive impact on the MPs' voting behavior on a law proposal to curb the spread of sexually transmitted diseases.
Comparative genomics reveals adaptations of a halotolerant thaumarchaeon in the interfaces of brine pools in the Red Sea
Authors: Kamanda Ngugi David , Blom Jochen , Alam Intikhab , Rashid Mamoon , Ba-Alawi Wail , Zhang Guishan , Hikmawan Tyas , Guan Yue , Antunes Andre , Siam Rania , El Dorry Hamza , Bajic Vladimir , Stingl Ulrich
Published: August 2014

The bottom of the Red Sea harbors over 25 deep hypersaline anoxic basins that are geochemically distinct and characterized by vertical gradients of extreme physicochemical conditions. Because of strong changes in density, particulate and microbial debris get entrapped in the brine-seawater interface (BSI), resulting in increased dissolved organic carbon, reduced dissolved oxygen toward the brines and enhanced microbial activities in the BSI. These features coupled with the deep-sea prevalence of ammonia-oxidizing archaea (AOA) in the global ocean make the BSI a suitable environment for studying the osmotic adaptations and ecology of these important players in the marine nitrogen cycle. Using phylogenomic-based approaches, we show that the local archaeal community of five different BSI habitats (with up to 18.2% salinity) is composed mostly of a single, highly abundant Nitrosopumilus-like phylotype that is phylogenetically distinct from the bathypelagic thaumarchaea; ammonia-oxidizing bacteria were absent. The composite genome of this novel Nitrosopumilus-like subpopulation (RSA3) co-assembled from multiple single-cell amplified genomes (SAGs) from one such BSI habitat further revealed that it shares ∼54% of its predicted genomic inventory with sequenced Nitrosopumilus species. RSA3 also carries several, albeit variable gene sets that further illuminate the phylogenetic diversity and metabolic plasticity of this genus. Specifically, it encodes for a putative proline-glutamate ‘switch’ with a potential role in osmotolerance and indirect impact on carbon and energy flows. Metagenomic fragment recruitment analyses against the composite RSA3 genome, Nitrosopumilus maritimus, and SAGs of mesopelagic thaumarchaea also reiterate the divergence of the BSI genotypes from other AOA.
Genetic Evidence of African Slavery at the Beginning of the Trans-Atlantic Slave Trade
Authors: Martiniano Rui , Coelho Catarina , Ferreira Maria Teresa , Neves Maria João , Pinhasi Ron , Bradley Daniel G.
Published: August 2014

An archaeological excavation in Valle da Gafaria (Lagos, Portugal), revealed two contiguous burial places outside the medieval city walls, dating from the 15th–17th centuries AD: one was interpreted as a Leprosarium cemetery and the second as an urban discard deposit, where signs of violent, unceremonious burials suggested that these remains may belong to slaves captured in Africa by the Portuguese. We obtained random short autosomal sequence reads from seven individuals: two from the latter site and five from the Leprosarium and used these to call SNP identities and estimate ancestral affinities with modern reference data. The Leprosarium site samples were less preserved but gave some probability of both African and European ancestry. The two discard deposit burials each gave African affinity signals, which were further refined toward modern West African or Bantu genotyped samples. These data from distressed burials illustrate an African contribution to a low status stratum of Lagos society at a time when this port became a hub of the European trade in African slaves which formed a precursor to the transatlantic transfer of millions.
Quantum cutting in nanoparticles producing two green photons
Authors: Lorbeer C. , Mudring A.-V.
Published: August 2014

Green quantum cutting can be achieved in nanoscale materials irrespective of a large surface and other killer traps.
Magnetically stabilized Fe8(μ4-S)6S8 clusters in Ba6Fe25S27
Authors: Stacey Timothy E. , Borg Christopher K. H. , Zavalij Peter J. , Rodriguez Efrain E.
Published: August 2014

We have prepared Ba6Fe25S27, and studied its magnetic properties and electronic structure. Using a combined DFT and molecular orbital based approach, we provide an interpretation of the bonding and stability within Ba6M25S27 (M = Fe, Co, Ni) and related M9S8 phases.
Synthesis and reactivity of coordinatively unsaturated halocarbonyl molybdenum PNP pincer complexes
Authors: de Aguiar Sara R. M. M. , Öztopcu Özgür , Stöger Berthold , Mereiter Kurt , Veiros Luis F. , Pittenauer Ernst , Allmaier Günter , Kirchner Karl
Published: August 2014

A series of six-coordinate neutral 16e halocarbonyl Mo(ii) complexes of the type [Mo(PNPMe-iPr)(CO)X2] (X = I, Br, Cl) were prepared and fully characterized.
Graphene oxide nanoribbons exhibit significantly greater toxicity than graphene oxide nanoplatelets
Authors: Khim Chng Elaine Lay , Chua Chun Kiang , Pumera Martin
Published: August 2014

Graphene oxide (GOs) has emerged in recent years as a versatile nanomaterial, demonstrating tremendous potential for multifunctional biomedical applications.
Polyphenylenes and the related copolymer membranes for electrochemical device applications
Authors: Zhang X. , Higashihara T. , Ueda M. , Wang L.
Published: August 2014

This review highlights recent advances in the development of polyphenylene-based ion exchange membranes for electrochemical device applications.
Defect mediated highly enhanced ultraviolet emission in P-doped ZnO nanorods
Authors: Sarkar Sanjit , Basak Durga
Published: August 2014

The enhancement in UVPL in hydrothermally grown P-doped ZnO is due to the formation of shallow acceptor PZn–2VZn complex defects.
Micelles consisting of choline phosphate-bearing Calix[4]arene lipids
Authors: Fujii Shota , Nishina Koichi , Yamada Shimpei , Mochizuki Shinichi , Ohta Noboru , Takahara Atsushi , Sakurai Kazuo
Published: August 2014

Choline phosphate bearing calix[4]arene based lipids form monodispersed micelles, and the micelles are taken up by cells through CP–PC interactions.
Hierarchical self-assembly of ‘hard–soft’ Janus particles into colloidal molecules and larger supracolloidal structures
Authors: Skelhon Thomas S. , Chen Yunhua , Bon Stefan A. F.
Published: August 2014

We demonstrate the self-assembly of ‘hard–soft’ micron-sized Janus particles into clusters in aqueous media. Upon the coalescence of the soft polymeric lobes, the newly formed clusters adopt a minimized surface area to volume ratio forming distinct microscopic supracolloidal structures.
Dealloyed PtCo hollow nanowires with ultrathin wall thicknesses and their catalytic durability for the oxygen reduction reaction
Authors: Huang Yan , Garcia Miguel , Habib Syed , Shui Jianglan , Wagner Frederick T. , Zhang Junliang , Jorné Jacob , Li James C. M.
Published: August 2014

Long PtCo hollow nanowires with ultrathin wall thicknesses of only 2–4 nm (to the best of our knowledge, these are the thinnest walls by similar methods) show significantly well-preserved durability for the oxygen reduction reaction.
EXAFS and FTIR studies of selenite and selenate sorption by alkoxide-free sol–gel generated Mg–Al–CO3 layered double hydroxide with very labile interlayer anions
Authors: Chubar Natalia
Published: August 2014

This work is the first theoretical explanation of why it is more difficult to sorb selenate than selenite.
High storage capacity and separation selectivity for C2 hydrocarbons over methane in the metal–organic framework Cu–TDPAT
Authors: Liu Kang , Ma Dingxuan , Li Baiyan , Li Yi , Yao Kexin , Zhang Zhijuan , Han Yu , Shi Zhan
Published: August 2014

We report an rht-type metal–organic framework (MOF) which exhibits a high adsorption capacity for C2 hydrocarbons and excellent selectivity over CH4. This MOF displays the highest reported C2H2–CH4 selectivity of 127.1 as well as a record high value for C2H4 adsorption enthalpy (49.5 kJ mol−1).
Application of human cell transformation assay on assessment of carcinogenic potential of river organic pollutants
Authors: Xing Xiumei , Zeng Xiaowen , Li Daochuan , Chen Liping , Zhu Xiaonian , He Zhini , Zhang Shixin , Ma Lu , Bai Qing , Zhang Zhengbao , Liu Caixia , Gao Chen , Li Jie , Sun Xin , Zheng Yuxin , Chen Wen , Xiao Yongmei
Published: August 2014

A human cell transformation assay was used to evaluate the carcinogenic potential of organic extracts of water pollutants collected from the Jialu River.
Precise indoor localisation technology based on TR‐FMM
Authors: Chen Guoping , Wang Li
Published: August 2014

Aiming to precisely locate a small mobile communication terminal in an indoor complex environment, a combination method, the time reversal‐fast marching method (TR‐FMM), is presented. The proposed method has been validated based on simulations in an indoor environment. The results demonstrate that it can build an excellent indoor channel model which is close to the actual environment. Localisation accuracy can be improved about 32.71 times than the regular TR method and the localisation error is 1.84 cm.
Development of EM‐CCD‐based X‐ray detector for synchrotron applications
Authors: Tutt J.H. , Hall D.J. , Soman M.R. , Holland A.D. , Warren A. , Connolley T. , Evagora A.M.
Published: August 2014

A high speed, low noise camera system for crystallography and X‐ray imaging applications is developed and successfully demonstrated. By coupling an electron‐multiplying (EM)‐CCD to a 3:1 fibre‐optic taper and a CsI(Tl) scintillator, it was possible to detect hard X‐rays. This novel approach to hard X‐ray imaging takes advantage of sub‐electron equivalent readout noise performance at high pixel readout frequencies of EM‐CCD detectors with the increase in the imaging area that is offered through the use of a fibre‐optic taper. Compared with the industry state of the art, based on CCD camera systems, a high frame rate for a full‐frame readout (50 ms) and a lower readout noise (<1 electron root mean square) across a range of X‐ray energies (6–18 keV) were achieved.
SVPWM strategy of post‐fault reconfigured dual inverter in open‐end winding motor drive systems
Authors: An Qun‐tao , Duan M.H. , Sun L. , Wang G.L.
Published: August 2014

A space vector pulse‐width modulation (SVPWM) strategy of the post‐fault reconfigured dual inverter in open‐end winding motor drive systems is discussed. The reconfigured dual H‐bridge inverter can produce the same distribution of space voltage vectors with the conventional two‐level inverters, but different switches are used to obtain these voltage vectors. A new seven‐segment SVPWM strategy suppressing the deadtime effect of insulated gate bipolar transistors in the same leg is presented, and its algorithm and implementation are discussed. The proposed method is validated by simulations and experiments.
Modelling of maximum power efficiency of charge pump circuits
Authors: Wong Oi‐Ying , Wong Hei , Tam Wing‐Shan , Kok Chi‐Wah
Published: August 2014

The loss estimation in a switched‐capacitor DC–DC converter has caused much controversy because of the uncertainty of the contribution of device parasitics to the power efficiency of a converter. Beginning from a simple equivalent circuit model, a closed‐form solution to the maximum achievable power efficiency of a converter in which both the effects of parasitic resistance and capacitance are taken into account is presented. It has been observed that the peak power efficiency of a Dickson charge pump depends mainly on the equivalent parasitic capacitance of a given technology and its operation mode, which is governed by the choices of the coupling capacitance, on‐resistance of the switch, as well as the operation frequency of the circuit.
Coplanar stripline‐fed compact UWB antenna
Authors: Roshna T.K. , Deepak U. , Sajitha V.R. , Mohanan P.
Published: August 2014

A novel compact coplanar stripline (CPS)‐fed antenna for ultra‐wideband (UWB) application is investigated. The proposed antenna consists of a staircase‐shaped radiator together with a shorted strip. The prototype is designed on a substrate of dielectric constant 4.4, with an overall size of 25 × 7 × 1.6 mm3. The antenna offers a 2:1 voltage standing wave ratio (VSWR) bandwidth from 3.1 to 11.4 GHz, with an average gain of 3 dBi and average radiation efficiency of 75% throughout the band. The measured group delay and transmission characteristics show that the proposed antenna is a good candidate for UWB communication systems.
Training data selection method for adaptive beamforming
Authors: Dai Baoquan , Wang Tong , Bai Tao , Wu Jianxin , Bao Zheng
Published: August 2014

A method for adaptively selecting training data is proposed to improve the performance of adaptive beamforming. The method first measures the contribution of each snapshot to the covariance matrix required by the beamforming using the sparse iterative covariance‐based estimation technique. Then, those snapshots making larger contributions are selected as the final training samples. The homogeneity of training samples can be improved significantly, and thus results in an evident performance improvement in adaptive beamforming. Simulation results demonstrate the effectiveness of the proposed method.
Weight updating floating‐gate synapse
Authors: Hindo T.
Published: August 2014

A novel floating‐gate synapse circuit is designed to update the weight in spike time dependent plasticity (STDP) system. The update of the weight is implemented through tunnelling and injection mechanisms using floating‐gate metal–oxide semiconductor field‐effect transistors. The importance of this circuit is for obtaining a storage mechanism for synaptic strength to implement the learning signal processing application on silicon. A novel floating‐gate synapse circuit and a new integrate‐and‐fire neuron model are described to implement weight updating in a STDP system.
Finite‐time consensus for second‐order multi‐agent systems with saturated control protocols
Authors: Zhao Yu , Duan Zhisheng , Wen Guanghui
Published: August 2014

This study investigates the distributed finite‐time consensus problem of networked agents with second‐order integrators. First of all, to achieve finite‐time consensus, a saturated protocol is proposed based on both relative position and relative velocity measurements. In light of the tools from homogeneous theory, it is theoretically shown that the proposed protocol will guarantee finite‐time consensus under bounded control inputs. Then, based only on the relative position measurements, an observer‐type protocol is developed and employed for achieving finite‐time consensus. Theoretical studies indicate that under the proposed algorithms, the states of the agents will achieve finite‐time consensus without velocity measurements. Finally, the effectiveness of the theoretical results is illustrated by numerical simulations.
Speckle filtering of ultrasound images using a modified non‐linear diffusion model in non‐subsampled shearlet domain
Authors: Gupta Deep , Anand Radhey Shyam , Tyagi Barjeev
Published: August 2014

Speckle filtering is of great interest for the ultrasound medical images in which various noises and artefacts are introduced because of various limitations of the acquisition systems and techniques. Speckle is a prime factor to degrade the quality and most importantly, texture information present in the ultrasound images. This study presents a despeckling method based on a modified non‐linear diffusion model and non‐subsampled shearlet transform (NSST). As a new image representation method with the different features of localisation, directionality and multiscale, the NSST is utilised to provide the effective representation of the image coefficients. The modified anisotropic diffusion is applied to the noisy coarser NSST coefficients to improve the denoising efficiency and preserve the edge features effectively. In the diffusion process, the non‐local pixel information is incorporated to evaluate the gradient of eight connected neighbouring pixels with an adaptive grey variance. The performance of the proposed method is evaluated for both the standard test and real ultrasound images. Experimental results show that the proposed method produces better results of noise suppression with the preservation of more edges compared with several existing methods.
Interval‐based analysis of pattern distortions in reflector antennas with bump‐like surface deformations
Authors: Rocca Paolo , Manica Luca , Massa Andrea
Published: August 2014

The effects on the radiated power pattern of localised defects (also called ‘bump‐like surface deformations’) in the surface of reflector antennas are studied with an innovative approach based on interval analysis (IA). By exploiting the features of the IA and the rules of the arithmetic for intervals, closed‐form relationships for the bounds (i.e. upper and lower values) of the power pattern are derived once bump‐like deformations with known locations and sizes, but unknown depths, are present. The sensitivity of the nominal power pattern and its features (i.e. sidelobe level, half‐power beamwidth and power peak) are analysed in the case of both single and multiple localised defects. Representative results from several numerical tests concerned with different sizes, locations and number of the surface deformations are reported and discussed to give the interested reader some insights on the capabilities and the effectiveness of the proposed IA‐based approach.
Shunt semi‐active power factor correction circuit for permanent magnet synchronous motor driver
Authors: Chern Tzuen‐Lih , Huang Tsung‐Mou
Published: August 2014

This study developed a shunt‐based, semi‐active power factor correction (PFC) circuit for a sensor‐less speed controller applicable in permanent magnet synchronous motors (PMSM). The objective of this novel approach is to increase the PF of the control circuit in order to improve the effectiveness of controlling the speed of the motor. The proposed circuit includes two parallel rectifiers capable of providing good PFC while maintaining simplicity. This study discusses the relevant theories, introduces the components and provides a simulation of the system. Experimental results, involving a sensor‐less PMSM rotary compressor for an air conditioning unit, demonstrate the efficacy of the proposed device over a wide range of speeds and duty times. The performance was further compared with two other circuits, the results of which prove that this system accomplished the objectives of the study.
Simultaneous fabrication of a through‐glass interconnect via and a bump using dry film resist and submicron gold particles
Authors: Mimatsu Hayata , Mizuno Jun , Shoji Shuichi , Kasahara Takashi , Shih Kailing , Nomura Kazuya , Kanehira Yukio , Ogashiwa Toshinori
Published: August 2014

A process for the simultaneous fabrication of through‐glass interconnect vias (TGVs) and gold (Au) bumps using dry film resist and submicron Au particles is proposed. A Ti/Pt/Au layer was sputtered on the top and bottom surfaces of glass vias to improve the adhesion between the glass substrate and submicron Au particles. The submicron Au particles filled the resist holes and glass vias fabricated by photolithography and by the two‐electrode method, respectively, and were then sintered. The height and diameter of the fabricated Au bumps were about 20–25 and 200 µm, respectively. The Ti/Pt/Au layer on the surface of the glass substrate was removed by Ar ion milling to isolate each bump electrically. The resistance of a single Au bump and TGV was evaluated using the four‐wire ohm method to be about 0.05 Ω. Furthermore, Au bump bonding was demonstrated. Fractured Au bumps and TGVs were observed by scanning electron microscopy after the bonded sample was peeled. It is expected that this fabrication process using a dry film resist and submicron Au particles will be useful in simple packaging processes to form glass interposer substrates or glass integrated circuit chips.
Performance and data analysis aspects of the new DIII-D monostatic profile reflectometer system
Authors: Zeng L. , Peebles W. A. , Doyle E. J. , Rhodes T. L. , Crocker N. , Nguyen X. , Wannberg C. W. , Wang G.
Published: August 2014

A new frequency-modulated profile reflectometer system, featuring a monostatic antenna geometry (using one microwave antenna for both launch and receive), has been installed on the DIII-D tokamak, providing a first experimental test of this measurement approach for profile reflectometry. Significant features of the new system are briefly described in this paper, including the new monostatic arrangement, use of overmoded, broadband transmission waveguide, and dual-polarization combination/demultiplexing. Updated data processing and analysis, and in-service performance aspects of the new monostatic profile reflectometer system are also presented. By using a raytracing code (GENRAY) to determine the approximate trajectory of the probe beam, the electron density (ne) profile can be successfully reconstructed with L-mode plasmas vertically shifted by more than 10 cm off the vessel midplane. Specifically, it is demonstrated that the new system has a capability to measure ne profiles with plasma vertical offsets of up to ±17 cm. Examples are also presented of accurate, high time and spatial resolution density profile measurements made over a wide range of DIII-D conditions, e.g., the measured temporal evolution of the density profile across a L-H transition.
Line strengths of rovibrational and rotational transitions within the ${\rm X}^3\Sigma \rm {^-}$X3Σ− ground state of NH
Authors: Brooke James S. A. , Bernath Peter F. , Western Colin M. , van Hemert Marc C. , Groenenboom Gerrit C.
Published: August 2014

A new line list for rovibrational and rotational transitions, including fine structure, within the NH ${\rm X}^3\Sigma \rm {^-}$X3Σ− ground state has been created. It contains line intensities in the form of Einstein A and f-values, for all possible bands up to v′ = 6, and for J up to between 25 and 44. The intensities are based on a new dipole moment function (DMF), which has been calculated using the internally contracted multi-reference configuration interaction method with an aug-cc-pV6Z basis set. The programs RKR1, LEVEL, and PGOPHER were used to calculate line positions and intensities using the most recent spectroscopic line position observations and the new DMF, including the rotational dependence on the matrix elements. The Hund's case (b) matrix elements from the LEVEL output (available as Supplement 1 of the supplementary material) have been transformed to the case (a) form required by PGOPHER. New relative intensities for the (1,0) band have been measured, and the calculated and observed Herman-Wallis effects are compared, showing good agreement. The line list (see Supplement 5 of the supplementary material) will be useful for the study of NH in astronomy, cold and ultracold molecular systems, and in the nitrogen chemistry of combustion.
Phase modulation mode of scanning ion conductance microscopy
Authors: Li Peng , Liu Lianqing , Wang Yuechao , Yang Yang , Zhang Changlin , Li Guangyong
Published: August 2014

This Letter reports a phase modulation (PM) mode of scanning ion conductance microscopy. In this mode, an AC current is directly generated by an AC voltage between the electrodes. The portion of the AC current in phase with the AC voltage, which is the current through the resistance path, is modulated by the tip-sample distance. It can be used as the input of feedback control to drive the scanner in Z direction. The PM mode, taking the advantages of both DC mode and traditional AC mode, is less prone to electronic noise and DC drift but maintains high scanning speed. The effectiveness of the PM mode has been proven by experiments.
Resummed memory kernels in generalized system-bath master equations
Authors: Mavros Michael G. , Van Voorhis Troy
Published: August 2014

Generalized master equations provide a concise formalism for studying reduced population dynamics. Usually, these master equations require a perturbative expansion of the memory kernels governing the dynamics; in order to prevent divergences, these expansions must be resummed. Resummation techniques of perturbation series are ubiquitous in physics, but they have not been readily studied for the time-dependent memory kernels used in generalized master equations. In this paper, we present a comparison of different resummation techniques for such memory kernels up to fourth order. We study specifically the spin-boson Hamiltonian as a model system bath Hamiltonian, treating the diabatic coupling between the two states as a perturbation. A novel derivation of the fourth-order memory kernel for the spin-boson problem is presented; then, the second- and fourth-order kernels are evaluated numerically for a variety of spin-boson parameter regimes. We find that resumming the kernels through fourth order using a Padé approximant results in divergent populations in the strong electronic coupling regime due to a singularity introduced by the nature of the resummation, and thus recommend a non-divergent exponential resummation (the “Landau-Zener resummation” of previous work). The inclusion of fourth-order effects in a Landau-Zener-resummed kernel is shown to improve both the dephasing rate and the obedience of detailed balance over simpler prescriptions like the non-interacting blip approximation, showing a relatively quick convergence on the exact answer. The results suggest that including higher-order contributions to the memory kernel of a generalized master equation and performing an appropriate resummation can provide a numerically-exact solution to system-bath dynamics for a general spectral density, opening the way to a new class of methods for treating system-bath dynamics.
Transcritical generation of nonlinear internal waves in the presence of background shear flow
Authors: Stastna Marek , Walter Ryan
Published: August 2014

While the occurrence of large amplitude internal waves in the Earth's natural bodies of water is widely documented, the generation of these waves remains an active area of exploration. We discuss numerical simulations of transcritical flows of a density stratified fluid with a dual focus on the role of a background shear current and transitions of the background current from super to subcritical. We demonstrate that the presence of a background shear can lead to the formation of large quasi-trapped regions of high vorticity over the downstream slope of the topography, but that this vorticity leads to only moderate perturbations of the underlying pycnocline, and hence that a wave and instability can co-exist for long times. Subsequently, we demonstrate the existence of hysteresis in the wave amplitude when the current is accelerated to supercritical then decelerated to subcritical, as opposed to accelerated to the subcritical value from rest. Finally, we explore situations in which the background shear is strong enough to preclude the formation of solitary-like waves, and discuss possible implications for the coastal ocean.
Complex time paths for semiclassical wave packet propagation with complex trajectories
Authors: Petersen Jakob , Kay Kenneth G.
Published: August 2014

The use of complex-valued trajectories in semiclassical wave packet methods can lead to problems that prevent calculation of the wave function in certain regions of the configuration space. We investigate this so-called bald spot problem in the context of generalized Gaussian wave packet dynamics. The analysis shows that the bald spot phenomenon is essentially due to the complex nature of the initial conditions for the trajectories. It is, therefore, expected to be a general feature of several semiclassical methods that rely on trajectories with such initial conditions. A bald region is created when a trajectory, needed to calculate the wave function at a given time, reaches a singularity of the potential energy function in the complex plane at an earlier, real time. This corresponds to passage of a branch point singularity across the real axis of the complex time plane. The missing portions of the wave function can be obtained by deforming the time path for the integration of the equations of motion into the complex plane so that the singularity is circumvented. We present examples of bald spots, singularity times, and suitable complex time paths for one-dimensional barrier transmission in the Eckart and Gaussian systems. Although the bald regions for the Eckart system are often localized, they are found to be semi-infinite for the Gaussian system. For the case of deep tunneling, the bald regions for both systems may encompass the entire portion of space occupied by the transmitted wave packet. Thus, the use of complex time paths becomes essential for a treatment of barrier tunneling.
Structure of single polythiophene molecules on Au(001) prepared by in situ UHV electrospray deposition
Authors: Förster Stefan , Widdra Wolf
Published: August 2014

Poly(3-hexylthiophene) (P3HT) adsorption on the quasihexagonally reconstructed Au(001) surface via differentially pumped electrospray deposition is reported. In situ scanning tunneling microscopy reveals a complex adsorption behaviour of P3HT. Weakly adsorbed chains are found which exhibit a 2D random coil like chain configuration across the reconstructed surface. Other molecules are constraint into a fully stretched configuration along the [110] high-symmetry directions of the square Au(001) lattice indicating a strong molecule-substrate interaction. This adsorption is accompanied by local lifting of the reconstruction underneath the polymer chains.
Polarization dependence of thermo-optic coefficients in polyimide films originating from chain orientation and residual thermal stress
Authors: Terui Yoshiharu , Ando Shinji
Published: August 2014

Control of polarization dependences of thermo-optic (TO) coefficients, i.e., the temperature dependence of birefringence (d(Δn)/dT), is critical issue for optical materials. Especially in active optical components like TO switches, polarization dependent behaviors are caused by d(Δn)/dT of materials. Origins of polarization dependence of TO coefficient were investigated for seven kinds of polyimide (PI) films in terms of main chain orientation and residual thermal stress. The values of d(Δn)/dT of PI films originated from chain orientation vary from nil to negative as the degrees of in-plane orientation increase. Magnitudes of d(Δn)/dT depend on intrinsic birefringences, second order orientation coefficients, and their temperature dependence. On the other hand, those of d(Δn)/dT originated from residual stress are negative for PI films exhibiting large in-plane coefficients of thermal expansion (CTE) and vary to zero as their CTE decreases due to reduced residual stress. d(Δn)/dT originating from chain orientation decreases as the degree of chain orientation increases, but that from residual thermal stress increases, which is the reason that no apparent trend was observed for the d(Δn)/dT of PI films adhering to Si substrates. Based on these examinations, the d(Δn)/dT of on-substrate PI films were successfully decreased to the levels of peeled PI films by incorporation of alicyclic structures in the main chains and/or the use of PI substrates whose CTEs are close to those of PI films.
Sign of the spin-polarization in cobalt-iron nitride films determined by the anisotropic magnetoresistance effect
Authors: Ito Keita , Kabara Kazuki , Sanai Tatsunori , Toko Kaoru , Imai Yoji , Tsunoda Masakiyo , Suemasu Takashi
Published: August 2014

We present the anisotropic magnetoresistance (AMR) properties in Fe4N, Co3FeN and Co4N epitaxial thin films grown on SrTiO3(001) substrates using molecular beam epitaxy. A negative AMR effect was observed in the Fe4N and Co3FeN films below 300 K. This behavior was attributed to the negative spin-polarizations of both the electrical conductivity and density of states at the Fermi level. The sign of the AMR ratio changed at ∼140 K in the Co4N film and was negative below 140 K. Diffraction lines corresponding to the (100) plane were clearly observed in the ϕ-2θχ (in-plane) x-ray diffraction patterns for the Fe4N and Co3FeN films but not for the Co4N film. This indicated that nitrogen atoms were present at the body center of each unit cell in the Fe4N and Co3FeN films, whereas they were lacking in the Co4N film. This assumption is discussed with energetic calculations using a spin density-functional theory.