bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Genomic Screening of a Saccharomyces cerevisiae Genomewide Mutant Collection Reveals Genes Required for Defense against Four Antimicrobial Peptides Derived from Proteins Found in Human Saliva
Authors: Lis Maciej , Bhatt Sanjay , Schoenly Nathan E. , Lee Anna Y. , Nislow Corey , Bobek Libuse A.
Published: December 2012

To compare the effects of four antimicrobial peptides (MUC7 12-mer, histatin 12-mer, cathelicidin KR20, and a peptide containing lactoferricin amino acids 1 to 11) on the yeast
Saccharomyces cerevisiae
, we employed a genomewide fitness screen of combined collections of mutants with homozygous deletions of nonessential genes and heterozygous deletions of essential genes. When an arbitrary fitness score cutoffs of 1 (indicating a fitness defect, or hypersensitivity) and −1 (indicating a fitness gain, or resistance) was used, 425 of the 5,902 mutants tested exhibited altered fitness when treated with at least one peptide. Functional analysis of the 425 strains revealed enrichment among the identified deletions in gene groups associated with the Gene Ontology (GO) terms “ribosomal subunit,” “ribosome biogenesis,” “protein glycosylation,” “vacuolar transport,” “Golgi vesicle transport,” “negative regulation of transcription,” and others. Fitness profiles of all four tested peptides were highly similar, particularly among mutant strains exhibiting the greatest fitness defects. The latter group included deletions in several genes involved in induction of the RIM101 signaling pathway, including several components of the ESCRT sorting machinery. The RIM101 signaling regulates response of yeasts to alkaline and neutral pH and high salts, and our data indicate that this pathway also plays a prominent role in regulating protective measures against all four tested peptides. In summary, the results of the chemical genomic screens of
S. cerevisiae
mutant collection suggest that the four antimicrobial peptides, despite their differences in structure and physical properties, share many interactions with
S. cerevisiae
cells and consequently a high degree of similarity between their modes of action.
Phase Diagrams Map the Properties of Antiviral Agents Directed against Hepatitis B Virus Core Assembly
Authors: Li Lichun , Chirapu Srinivas Reddy , Finn M. G. , Zlotnick Adam
Published: December 2012

Assembly effectors are small molecules that induce inappropriate virus capsid assembly to antiviral effect. To identify attributes of hepatitis B virus (HBV) assembly effectors, assembly reaction products (normal capsid, noncapsid polymer, intermediates, and free dimeric core protein) were quantified in the presence of three experimental effectors: HAP12, HAP13, and AT-130. Effectors bound stoichiometrically to capsid protein polymers, but not free protein. Thermodynamic and kinetic effects, not aberrant assembly, correlate with maximal antiviral activity.
Multilaboratory Approach to Preclinical Evaluation of Vaccine Immunogens for Placental Malaria
Authors: Fried Michal , Avril Marion , Chaturvedi Richa , Fernandez Pablo , Lograsso Joseph , Narum David , Nielsen Morten A. , Oleinikov Andrew V. , Resende Mafalda , Salanti Ali , Saveria Tracy , Williamson Kathryn , Dicko Alassane , Scherf Artur , Smith Joseph D. , Theander Thor G. , Duffy Patrick E.
Published: December 2012

Pregnancy malaria is caused by
Plasmodium falciparum
-infected erythrocytes that adhere to the placental receptor chondroitin sulfate A (CSA) and sequester in the placenta; women become resistant to pregnancy malaria as they acquire antiadhesion antibodies that target surface proteins of placental parasites. VAR2CSA, a member of the
P. falciparum
EMP1 variant surface antigen family, is the leading candidate for a pregnancy malaria vaccine. Because VAR2CSA is a high-molecular-weight protein, a vaccine based on the full-length protein may not be feasible. An alternative approach has been to develop a vaccine targeting individual Duffy binding-like (DBL) domains. In this study, a consortium of laboratories under the Pregnancy Malaria Initiative compared the functional activity of antiadhesion antibodies elicited by different VAR2CSA domains and variants produced in prokaryotic and eukaryotic expression systems. Antisera were initially tested against laboratory lines of maternal parasites, and the most promising reagents were evaluated in the field against fresh placental parasite samples. Recombinant proteins expressed in
Escherichia coli
elicited antibody levels similar to those expressed in eukaryotic systems, as did the two allelic forms of the DBL4 and DBL5 domains. The procedures developed for this head-to-head comparison will be useful for future evaluation and down-selection of malaria vaccine immunogens.
Fever of unknown origin in pregnancy: the need for a full history
Authors: Milne Kim , Dallard Tara , Douglas J Graham
Published: December 2012

A 26-year-old woman with 29 weeks gestation presented with headache, photophobia and fever. She had deranged liver function tests and low platelets on admission. Blood film, performed to look for haemolysis, revealed she hadPlasmodium vivaxmalaria, despite not having travelled to an endemic malaria area for over 1 year. The diagnosis was confirmed on PCR test performed in the HPA malaria reference laboratory in London and she was treated with chloroquine. She delivered a healthy baby at 33+3 weeks gestation, and once the patient and the baby had both tested negative for glucose-6-phospate dehydrogenase deficiency, she was given primaquine to clear the hypnozoite phase in the liver. This case highlights the importance of an extended travel history in a patient with fever of unknown origin and the difficulties of treating non-falciparum malaria in pregnancy.
Diagnosis and management of life-threatening hypermenorrhagia caused by uterine arteriovenous malformation secondary to surgical termination of pregnancy: video evidence!
Authors: Clarke Joseph Adam , Viswanatha Radhika Kashi , Hamid Rosol , Sankaranarayanan Subha
Published: December 2012

A 23-year-old lady presented with a 10-month history of multiple episodes of prolonged and erratic menstrual bleeding having undergone a surgical termination of pregnancy. Initially, pelvic ultrasound and hysteroscopy were found to be normal and for many months she was treated pharmacologically for dysfunctional uterine bleeding. She also tried both a copper-coil and MIRENA intrauterine system, which were both expelled due to heavy bleeding characterised by ‘a clot the size of two fists’. She required blood transfusions on multiple admissions, was forced to resign from her job and later became depressed. Under our care a transvaginal ultrasound scan showed a hypervascular region on the posterior uterine wall. An urgent hysteroscopy was performed due to her haemoglobin being 5.7 g/dl and revealed a pulsating lesion abutting the endometrium, which can be seen here on video. MR angiography confirmed an arteriovenous malformation and she was successfully treated with uterine artery embolisation.
Artificial microRNA (amiRNA) induced gene silencing in alfalfa (Medicago sativa)
Authors: Verdonk Julian C. , Sullivan Michael L.
Published: December 2012

Gene silencing is a powerful technique that allows the study of the function of specific genes by selectively reducing their transcription. Several different approaches can be used, however they all have in common the artificial generation of single stranded small ribonucleic acids (RNAs) that are utilized by the endogenous gene silencing machinery of the organism. Artificial microRNAs (amiRNA) can be used to very specifically target genes for silencing because only a short sequence of 21 nucleotides of the gene of interest is used. Gene silencing via amiRNA has been developed for Arabidopsis thaliana (L.) Heynh. and rice using endogenous microRNA (miRNA) precursors and has been shown to also work effectively in other dicot species using the arabidopsis miRNA precursor. Here, we demonstrate that the arabidopsis miR319 precursor can be used to silence genes in the important forage crop species alfalfa (Medicago sativa L.) by silencing the expression of a transgenic beta-glucuronidase (GUSPlus) target gene.
A comparison of enrichment and direct-plating methods for isolation of Listeria monocytogenes from surface water
Authors: Lyautey Emilie , Hartmann Alain , Lapen David R. , Topp Edward
Published: December 2012

Listeria monocytogenes is a facultative intracellular pathogen distributed in the environment. Reference isolation methods include an enrichment step. We compared 2 protocols: one based on enrichment and the other on direct plating, with respect to the efficiency of isolation of L. monocytogenes from surface water samples. From March to May 2006, 126 surface water samples were collected biweekly from 24 discrete sampling sites located in the South Nation River basin (Ontario). Presumptive Listeria spp. were isolated using the 2 methods, and L. monocytogenes isolates were confirmed based on colony morphology and amplification of 3 pathogenicity genes: iap, inlA, and hlyA. Listeria monocytogenes was detected in 31 water samples using the enrichment approach and in 27 using the direct-plating approach, with only 13 samples positive using both approaches. No correlation was observed between the ability of the enrichment procedure to fail in the detection of the pathogenic bacterium and the abundance of several indicator bacteria. The proportion of samples carrying isolates from serovar groups 1/2a, 3a; 1/2b, 3b, 7; 4b, 4d, 4e; and Listeria spp. was significantly different between the 2 approaches. This data indicate that a direct-plating approach would be suitable for the detection of L. monocytogenes in water samples, but that enrichment and direct-plating protocols both have specific biases.
A new set of reference genes for RT-qPCR assays in the yeast Dekkera bruxellensis
Authors: de Barros Pita Will , Leite Fernanda Cristina Bezerra , de Souza Liberal Anna Theresa , Pereira Luciana Filgueira , Carazzolle Marcelo Falsarella , Pereira Gonçalo Amarante , de Morais Marcos Antonio
Published: December 2012

The yeast Dekkera bruxellensis has been recently regarded as an important microorganism for bioethanol production owing to its ability to convert glucose, sucrose, and cellobiose to ethanol. The aim of this work was to validate a new set of reference genes for gene expression analysis by quantitative real-time PCR in D. bruxellensis and compare the influence of the method of choice for quantification of mRNA levels with the reliability of our data. Three candidate reference genes, DbEFA1, DbEFB1, and DbYNA1, were used in a quantitative analysis of 4 genes of interest, DbYNR1, DbTPS1, DbADH7, and DbUBA4, based on an approach for calculating the normalization factors by means of the geNorm applet. Each reference gene was also individually used for a [Formula: see text] (comparative Cq method) calculation of the relative expression of genes of interest. Our results showed that the 3 reference genes provided enough stability and were complementary to the normalization factors method in different culture conditions. This work was able to confirm the usefulness of a previously reported reference gene, EFA1/TEF1, and increased the set of possible reference genes in D. bruxellensis to 4. Moreover, this can improve the reliability of the analysis of the regulation of gene expression in the industrial yeast D. bruxellensis.
Effect of starvation, body size, and temperature on the onset of metamorphosis in Japanese eel (Anguilla japonica)
Authors: Okamura Akihiro , Yamada Yoshiaki , Mikawa Naomi , Horie Noriyuki , Tsukamoto Katsumi
Published: December 2012

We assessed the effects of starvation, body size, and water temperature on the onset of metamorphosis in leptocephali of Japanese eel ( Anguilla japonica Temminck and Schlegel, 1846) as determined by the morphological criteria of proportion, preanal length, and body depth to total length. Leptocephali of mean total length 55.6 mm that had been reared in captivity for 241 days from hatching were divided into unfed (n = 28) and fed (n = 30) groups in triplicate and reared for an additional 2 weeks. The mean percentage of larvae starting metamorphosis within 2 weeks was significantly higher in the unfed than in the fed groups (70% vs. 28.6%), suggesting that food deprivation acted as a cue for metamorphosis. The critical size for metamorphosis was a total length of 50–55 mm; smaller larvae did not start metamorphosis even in the absence of food, whereas larvae reaching that critical size were induced to undergo metamorphosis by starvation. The start of metamorphosis under unfed conditions was independent of diel-varying water temperature (day 23 °C; night 21–29 °C), suggesting a high plasticity in response to a wide range of environmental temperatures. These findings suggest methods for the efficient production of glass eels, as well as new insights into the mechanism of eel metamorphosis.
Assessment of the mode of action of polyhexamethylene biguanide against Listeria innocua by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis
Authors: Chadeau Elise , Dumas Emilie , Adt Isabelle , Degraeve Pascal , Noël Claude , Girodet Christophe , Oulahal Nadia
Published: December 2012

Polyhexamethylene biguanide (PHMB) is a cationic biocide. The antibacterial mode of action of PHMB (at concentrations not exceeding its minimal inhibitory concentration) upon Listeria innocua LRGIA 01 was investigated by Fourier transformed infrared spectroscopy and fluorescence anisotropy analysis. Fourier transformed infrared spectra of bacteria treated with or without PHMB presented some differences in the lipids region: the CH2/CH3 (2924 cm–1/2960 cm–1) band areas ratio significantly increased in the presence of PHMB. Since this ratio generally reflects membrane phospholipids and membrane microenvironment of the cells, these results suggest that PHMB molecules interact with membrane phospholipids and, thus, affect membrane fluidity and conformation. To assess the hypothesis of PHMB interaction with L. innocua membrane phospholipids and to clarify the PHMB mode of action, we performed fluorescence anisotropy experiments. Two probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and its derivative 1-[4-(trimethyl-amino)-phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH), were used. DPH and TMA-DPH incorporate inside and at the surface of the cytoplasmic membrane, respectively. When PHMB was added, an increase of TMA-DPH fluorescence anisotropy was observed, but no changes of DPH fluorescence anisotropy occurred. These results are consistent with the hypothesis that PHMB molecules perturb L. innocua LRGIA 01 cytoplasmic membrane by interacting with the first layer of the membrane lipid bilayer.
Effects of arsenic trioxide (As2O3) on airway remodeling in a murine model of bronchial asthma
Authors: Xu Zi-ping , Huo Jian-min , Sang Yu-lan , Kang Jian , Li Xue
Published: December 2012

We investigated the effects of arsenic trioxide (As2O3) as a possible approach for preventing airway remodeling in a murine model of bronchial asthma induced by ovalbumin (OVA) challenge. Forty Balb/c mice were randomly assigned to 1 of 4 groups (10 mice/group) as follows: controls (challenged with sterile saline inhalation only); OVA-challenged, no treatment; OVA-challenged, treated with dexamethasone; and OVA-challenged, treated with As2O3. All mice were sensitized by intraperitoneal injection with 10% OVA at 2 weeks prior to saline or OVA inhalation challenge. Challenges were for 8 weeks. After OVA challenge, typical asthma-like morphology changes in the bronchi and lung tissues were observed by hematoxylin–eosin staining and pulmonary function indices were reduced compared with controls. Changes in pulmonary indices and lung tissues were similar in the dexamethasone and As2O3 groups and were in between those of the untreated and control groups. Compared with the untreated group, transforming growth factor β1, vascular endothelial growth factor, and matrix metalloproteinase-9 protein levels and mRNA expression were decreased in lung tissues of the dexamethasone and As2O3 groups. Our results suggest that steroids and As2O3 can inhibit airway remodeling in chronic asthma by mechanisms related to inhibiting the expression of the 3 aforementioned mediators.
Chiral recognition of doxazosin enantiomers in 3 targets for therapy as well as adverse drug reactions in animal experiments
Authors: Zhao Ding , Duan Li-Hua , Wang Feng-Yu , Wang Miao , Lu Hai-Gang , Wu Zhi-Gang , Wang Xue , Ren Lei-Ming
Published: December 2012

Doxazosin used in benign prostatic hyperplasia has the side effects of causing hypotension and the risk of heart failure. The 3 targets of α1A-adrenoceptors (in the prostate), α1D-adrenoceptors (in the aorta), and an unknown mechanism (in the heart) are involved, respectively. We hypothesized that there is a chiral recognition of doxazosin enantiomers in the 3 targets. Using isolated rat aorta (α1D-adrenoceptors) and rabbit prostate (α1A-adrenoceptors), we examined pA2 and pKB values of doxazosin enantiomers. We observed chronotropic and inotropic effects of doxazosin enantiomers in isolated rat and rabbit heart tissues. (–)Doxazosin and (+)doxazosin produced a shift to the right of concentration–contraction curves for noradrenalin (aorta) and phenylephrine (prostate smooth muscle). The pA2 value of (–)doxazosin (8.625 ± 0.053) was smaller than (+)doxazosin (9.503 ± 0.051) in rat aorta, but their pKB values in rabbit prostate were the same. In rat and rabbit heart tissues, (+)doxazosin (3–30 µmol·L−1) significantly decreased atrial rate, and produced negative inotropic effects; however, (–)doxazosin did not affect the atrial rate, and produced positive inotropic effects in the atria. Thus, the chiral carbon atom of doxazosin does not affect its activity at the therapeutic target of α1A-adrenoceptors in the prostate, but significantly changes its blocking activity against α1D-adrenoceptors in the aorta, and produces opposite inotropic effects in the atria via an α1-adrenoceptor-independent mechanism.
Electrical field stimulation induces cardiac fibroblast proliferation through the calcineurin–NFAT pathway
Authors: Chen Qing-Qing , Zhang Wei , Chen Xiang-Fan , Bao Yun-Jian , Wang Jing , Zhu Wei-Zhong
Published: December 2012

Most cardiac diseases are associated with fibrosis. Calcineurin (CaN) is regulated by Ca2+/calmodulin (CaM). The CaN–NFAT (nuclear factor of activated T cell) pathway is involved in the process of cardiac diseases, such as cardiac hypertrophy, but its effect on myocardial fibrosis remains unclear. The present study investigates whether the CaN–NFAT pathway is involved in cardiac fibroblast (CF) proliferation induced by electrical field stimulation (EFS), which recently became a popular treatment for heart failure and cardiac tissue engineering. CF proliferation was evaluated by a cell survival assay (MTT) and cell counts. Myocardial fibrosis was assessed by collagen I and collagen III protein expression. Green fluorescent protein (GFP)-tagged NFAT was used to detect NFAT nuclear translocation. CF proliferation, myocardial fibrosis, CaN activity, and NFAT nuclear translocation were enhanced by EFS. More importantly, these effects were abolished by CaN inhibitors, dominant negative CaN (DN-CaN), and CaN gene silenced with siRNA. Furthermore, buffering intracellular Ca2+ with BAPTA-AM and blocking Ca2+ influx with nifedipine suppressed EFS-induced increase in intracellular Ca2+ and CF proliferation. These results suggested that the CaN–NFAT pathway mediates CF proliferation, and that the CaN–NFAT pathway might be a possible therapeutic target for EFS-induced myocardial fibrosis and cardiac tissue engineering.
Effect of dialkyl- [2-(1-oxa-3,4,9-triaza-fluoren-2-yl-methoxy)ethyl] amines on biogenic amines: new potential antidepressants
Authors: Venkatesham Akena , Rao J. Venkateshwar , Kumar K. Vijay , Sarangapani M. , Devarakonda Krishna
Published: December 2012

A thorough survey of the literature has revealed that indole derivatives have shown various central nervous system activities. This study aims to evaluate the antidepressant activity of the newly synthesized dialkyl- [2-(1-oxa-3,4,9-triaza-fluoren-2-yl-methoxy)ethyl] amines and their effect on biogenic amines. In this study, the synthesized compounds were assessed by in-vivo antidepressant models, by forced swim test and tail suspension test in mice and effect of synthesized compounds on biogenic amines in brain in a chronic unpredictable stress model. The test compounds have demonstrated significant (P < 0.05) reduced immobility duration in mice when compared with the control group animals. The reduced immobility displayed by mice indicates potential antidepressant activity. In this study, chronic unpredictable stress led to decreased monoamine levels in the cortex and hippocampus regions of the brain. With chronic administration of the investigated compounds there is an increased in monoamines in the brain, in the chronic unpredictable stress model. Decreased levels of monoamines induced by the chronic unpredictable stress induced model of depression, were normalized by treatment with the test compounds, which indicates potential antidepressant activity.
Oxidized LDL enhances stretch-induced smooth muscle cell proliferation through alterations in nuclear protein import
Authors: Chahine Mirna N. , Dibrov Elena , Blackwood David P. , Pierce Grant N.
Published: December 2012

Mechanical stress contributes to hypertension and atherosclerosis partly through the stimulation of vascular smooth muscle cell (VSMC) proliferation. Oxidized low density lipoprotein (oxLDL) is another important atherogenic factor that can increase VSMC proliferation. The purpose of this study was to investigate whether oxLDL could further enhance the proliferative action of mechanical stretch on VSMC, and to determine the mechanism responsible for this interaction. Because nuclear protein import is critical in regulating gene expression, transcription, and cell proliferation, its involvement in the mitogenic effects of oxLDL and mechanical stress was studied. OxLDL enhanced the proliferative effects of mechanical stretch on its own in rabbit aortic VSMC, and induced increases in the expression of HSP60 in an additive manner. Adenoviral-mediated overexpression of HSP60 induced increases in cell proliferation compared with uninfected VSMC. Mechanical stretch and oxLDL stimulated the rate of nuclear protein import in VSMC and increased the expression of nucleoporins. These effects were sensitive to inhibition of the MAPK pathway. We conclude that oxLDL and mechanical stretch have a synergistic effect on VSMC proliferation. This synergistic effect is induced through a stimulation of nuclear protein import via HSP60 and an activation of the MAPK pathway.
MEASUREMENTS OF COSMIC RAYS WITH ICETOP/ICECUBE: STATUS AND RESULTS
Authors: TAMBURRO ALESSIO
Published: December 2012

The IceCube Observatory at the South Pole is composed of a cubic kilometer scale neutrino telescope buried beneath the icecap and a square-kilometer surface water Cherenkov tank detector array known as IceTop. The combination of the surface array with the in-ice detector allows the dominantly electromagnetic signal of air showers at the surface and their high-energy muon signal in the ice to be measured in coincidence. This ratio is known to carry information about the nuclear composition of the primary cosmic rays. This paper reviews the recent results from cosmic-ray measurements performed with IceTop/IceCube: energy spectrum, mass composition, anisotropy, search for PeV γ sources, detection of high energy muons to probe the initial stages of the air shower development, and study of transient events using IceTop in scaler mode.
A REVIEW OF PARTICLE ASTROPHYSICS WITH ICECUBE
Authors: TABOADA IGNACIO
Published: December 2012

IceCube is a neutrino detector sensitive to energies above 10 GeV. IceCube operates by sensing the Cherenkov light from secondary particles produced in neutrino-matter interactions. One gigaton of highly transparent Antarctic ice is instrumented to achieve this goal. Designed to be modular, IceCube has been collecting data since construction began in 2005. Construction was completed in December 2010. The primary goal of IceCube is to observe astrophysical sources of neutrinos. We present here a summary of IceCube's recent results in atmospheric neutrinos, point sources, diffuse fluxes of neutrinos, cosmogenic neutrinos, a lack of correlation between neutrinos and Gamma Ray Bursts and the search for dark matter.
DARK ENERGY IN MODIFIED SUPERGRAVITY
Authors: KETOV SERGEI V. , WATANABE NATSUKI
Published: December 2012

We propose a supersymmetric extension of the dynamical dark energy function and the scalar (super)potential in [Formula: see text] supergravity. Our model is viable in the Einstein approximation, and also has an analytic (regular) scalar potential. The hidden sector responsible for spontaneous supersymmetry breaking is also given.
COMPLEX-MASS SCHEME AND PERTURBATIVE UNITARITY
Authors: BAUER T. , GEGELIA J. , JAPARIDZE G. , SCHERER S.
Published: December 2012

We derive cutting rules for loop integrals containing propagators with complex masses. Using a field-theoretical model of a heavy vector boson interacting with a light fermion, we demonstrate that the complex-mass scheme respects unitarity order by order in a perturbative expansion provided that the renormalized coupling constant remains real.
SOME REMARKS ON D-BRANES AND DEFECTS IN LIOUVILLE AND TODA FIELD THEORIES
Authors: SARKISSIAN GOR
Published: December 2012

In this paper, we analyze the Cardy–Lewellen equation in general diagonal model. We show that in these models it takes a simple form due to some general properties of conformal field theories, like pentagon equations and OPE associativity. This implies that the Cardy–Lewellen equation has a simple form also in nonrational diagonal models. We specialize our finding to the Liouville and Toda field theories. In particular, we prove that recently conjectured defects in Toda field theory indeed satisfy the cluster equation. We also derive the Cardy–Lewellen equation in all sl(n) Toda field theories and prove that the form of boundary states found recently in sl(3) Toda field theory holds in all sl(n) theories as well.
STOCHASTIC DYNAMICS OF DC AND AC DRIVEN DISLOCATION KINKS
Authors: VARDANYAN A. , KTEYAN A.
Published: December 2012

Dynamics of a pinned dislocation kink controlled by the acting DC and AC forces is studied analytically. The motion of the kink, described by sine-Gordon (sG) equation, is explored within the framework of McLaughlin–Scott perturbation theory. Assuming weakness of the acting AC force, the equation of motion of the dislocation kink in the pinning potential is linearized. Based on the equations derived, we study stochastic behavior of the kink, and determine the probability of its depinning. The dependencies of the depinning probability on DC and AC forces are analyzed in detail.
SPIN AND PSEUDOSPIN SYMMETRIES IN RELATIVISTIC TRIGONOMETRIC PÖSCHL–TELLER POTENTIAL WITH CENTRIFUGAL BARRIER
Authors: HAMZAVI M. , IKHDAIR S. M. , THYLWE K.-E.
Published: December 2012

Approximate analytical solutions of the Dirac equation with the trigonometric Pöschl–Teller (tPT) potential are obtained for arbitrary spin-orbit quantum number κ using an approximation scheme to deal with the spin-orbit coupling terms κ(κ±1)r-2. In the presence of exact spin and pseudo-spin (p-spin) symmetric limitation, the bound state energy eigenvalues and the corresponding two-component wave functions of the Dirac particle moving in the field of attractive and repulsive tPT potential are obtained using the parametric generalization of the Nikiforov–Uvarov (NU) method. The case of nonrelativistic limit is studied too.
PERTURBATIVE APPROACH TO DIATOMIC LATTICES
Authors: SOTO-EGUIBAR FRANCISCO , MOYA-CESSA HÉCTOR MANUEL
Published: December 2012

By using a small rotation approach, we show that it is possible to obtain well behaved perturbed solutions for the amplitude of the electromagnetic field propagating in a photonic waveguide array. This array mimics the propagation of a quasiparticle among the sites of an infinite one-dimensional chain.
Improvement of Electrical Contact Reliability by Conductive Polymer Coated Elastomer Structure in Woven Electronic Textiles
Authors: Yamashita Takahiro , Takamatsu Seiichi , Miyake Koji , Itoh Toshihiro
Published: December 2012

This article presents an improvement in the stability and durability of the electrical contacts employed in flexible devices. A coating of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) in form of a solid conductive layer on a silicone elastomer structure is employed in creating an electrical circuit embedded into the fabric of a woven electronic textile, where the coating serves as an electrical contact between weft and warp ribbons. When the contact load increases to 1 mN, then, due to the flexibility of the structure, an electric current begins to flow through the circuit. The structure can sextuplicate the life of the electrical contact.
Valence States of Rare-Earth Ions and Band Gaps in RBiBa2O6(R = La, Ce, Pr, Nd, Sm, Gd, Eu, and Dy) Photocatalysts
Authors: Matsushita Akiyuki , Nakane Takayuki , Naka Takashi , Isago Hiroaki , Yamada Yoshihiro , Yamada Yuh
Published: December 2012

We have measured magnetic susceptibility, powder X-ray diffraction (XRD), and diffuse reflectance spectra of RBiBa2O6(R = La, Ce, Pr, Nd, Sm, Gd, Eu, and Dy). The valences of the rare earth elements estimated from magnetic susceptibility were trivalent except CeBiBa2O6and PrBiBa2O6in which Ce and Pr were tetravalent. In PrBiBa2O6, a significant effect of crystal fields on magnetic susceptibility was observed below 200 K. The (111) reflection in XRD, which is evidence for the R3+–O–Bi5+ordering in the double-perovskite structure, was observed in all samples except CeBiBa2O6. In PrBiBa2O6, a weak (111) reflection was observed suggesting that a small amount of Pr3+ions were present. The band gaps estimated from their optical spectra were approximately 0.7 eV for CeBiBa2O6, 1.1 eV for PrBiBa2O6, and 1.4–1.7 eV for R3+BiBa2O6. Thus the band-gaps were closely related to the valences of RBiBa2O6. We discuss the relationship between these physical properties and the photocatalytic activities previously reported.
Effects of the Defects on the Thermoelectric Properties of Cu–In–Te Chalcopyrite-Related Compounds
Authors: Kosuga Atsuko , Higashine Ryosuke , Plirdpring Theerayuth , Matsuzawa Mie , Kurosaki Ken , Yamanaka Shinsuke
Published: December 2012

We prepared and investigated the thermoelectric properties of Cu0.4InTe2 at 310–710 K. The crystal structure of Cu0.4InTe2 was identical to that of CuIn3Te5, namely a tetragonal structure, space group P4̄2c, known as an ordered defect chalcopyrite. This structure is different from that of CuInTe2, which has a normal chalcopyrite structure. In comparison with CuInTe2, Cu0.4InTe2 showed inferior thermoelectric properties because a degradation in its electrical conductivity outweighed a reduction in its thermal conductivity. The maximum dimensionless figure of merit of Cu0.4InTe2 was 0.17 at 702 K.
Improved Light Extraction of GaN-Based Blue Light-Emitting Diodes with ZnO Nanorods on Transparent Ni/Al-Doped ZnO Current Spreading Layer
Authors: Lee Hee Kwan , Joo Dong Hyuk , Ko Yeong Hwan , Yeh Yunhae , Kim Yong Pyung , Yu Jae Su
Published: December 2012

We reported the light-extraction properties of InGaN/GaN multiple quantum wells blue light-emitting diodes (LEDs) with ZnO nanorod arrays (NRAs) on Ni/Al-doped ZnO (AZO) films as a current spreading layer (CSL). The Ni/AZO bilayer exhibited a high optical transmittance of ∼80% at λ∼460 nm. The electrical property of AZO films was improved by inserting a thin Ni layer, which leads to the better current–voltage characteristics of LEDs. The ZnO nanorods can be easily grown on the AZO surface of Ni/AZO CBL as the same materials by a simple wet chemical growth. For 450 ×450 µm2 LED with Ni/AZO CSL, the incorporation of ZnO NRAs into the AZO surface improved the light output power by ∼14% at 100 mA without causing any electrical degradation compared to the conventional LED without ZnO NRAs.
Photoluminescence Study of Deep Levels in CuInS2 Thin Films Grown by Sulfurization Using Ditertiarybutylsulfide
Authors: Liu Xiaohui , Dou Xiaoming , Sugiyama Mutsumi
Published: December 2012

Photoluminescence (PL) spectroscopy measurements are carried out to determine the deep defect levels of Cu-rich CuInS2 thin films prepared by sulfurization using ditertiarybutylsulfide [(t-C4H9)2S: DTBS]. Several PL emission peaks were detected at 1.07, 1.01, and 0.93 eV in Cu-rich CuInS2 thin films. These peaks are considered to be due to both donor–acceptor pair emission as well as transitions related to trap. On the basis of excitation power dependent and temperature dependent PL measurements, the defect levels are calculated. Copper interstitial (Cui) was determined to be the deep donor level, which is easier to create in samples prepared under Cu-rich conditions. A new trap level at 625 meV below the conduction band was found. Using these data and our previous study data, the intrinsic defects are easier to exist in what kind of CuInS2 thin films is analyzed, a complete defect levels diagram of CuInS2 thin films is also proposed.
A Light-Stabilization Mechanism of Anionic Oxonol Dyes for Digital Versatile Disks
Authors: Tanabe Mamoru , Yokoyama Hiroshi , Miyashita Yousuke
Published: December 2012

A light-stabilization mechanism of anionic oxonol dyes for digital versatile disks (DVDs) with 4,4'-bipyridinium cations was analyzed by time-resolved spectroscopy techniques. The analysis showed that for the amorphous solid film of the anionic oxonol dye without 4,4'-bipyridinium cations, the short-lived component with 1.4 ns lifetime and long-lived components with millisecond timescale lifetime were observed: the short-lived component was assigned to the lowest excited singlet state (S1) and the long-lived components were assigned to the lowest excited triplet state (T1) and the metastable photoisomer of the dye. On the other hand, for the amorphous solid film with 4,4'-bipyridinium cations, ultrafast forward (4 ps) and backward (50 ps) electron transfers were observed and the S1 state of the dye was quenched. It was concluded that the observed electron transfer improved the lightfastness of the oxonol dye.
Feasibility Study on Terahertz Imaging of Corrosion on a Cable Metal Shield
Authors: Komatsu Marina , Sato Ryo , Mizuno Maya , Fukunaga Kaori , Ohki Yoshimichi
Published: December 2012

The possibility of nondestructive diagnosis of corrosion on a metallic shielding layer in a power cable by time-domain imaging and spectroscopic measurements using terahertz waves was examined experimentally. First, absorbance was measured in a THz frequency range for copper oxide, basic copper carbonate, and copper chloride. Next, two copper plates, uncorroded and corroded, were placed in contact with each other horizontally, and a terahertz wave was scanned over them in order to get two-dimensional images. When the plate is corroded to form either basic copper carbonate or copper chloride, the intensity of reflected wave becomes lower than when the plate is uncorroded. It seems that the terahertz wave was scattered more on the surface of the corroded copper plate and was absorbed by the corrosion. Therefore, this research indicates the feasibility of nondestructive diagnosis to detect corrosion on a shield metal in a power cable.
100-Nanosecond-Level Square-Pulse Generation in a Ring Cavity with a Tellurite Single-Mode Fiber
Authors: Gao Weiqing , Liao Meisong , Kawashima Hiroyasu , Cheng Tonglei , Suzuki Takenobu , Ohishi Yasutake
Published: December 2012

We demonstrate the square-pulse generation in a ring cavity with a 207 m tellurite single-mode fiber. The stable square pulse with the wide full width at half maximum (FWHM) of 118 ns is formed by the nonlinear polarization switching in the cavity. The high nonlinearity and birefringence of the tellurite fiber play the key role during the square-pulse formation and the net normal dispersion is advantageous for stabilizing the square pulse. When the linear phase delay bias is set close to the polarization switching point, the third-order harmonic pulses and multiple packets are observed under different pump powers.
Monte Carlo Simulation of Magnetization Recovery in Two-Dimensional Ferromagnetic System after Ultrafast Pump Pulses
Authors: Fang WenXiao , En YunFei , Zhou Bin , Huang QinWen , Liu Xin , Chen YiQiang
Published: December 2012

The magnetization recovery of a two-dimensional ferromagnetic system after excitation by intensive ultrafast pump pulses is investigated by a Monte Carlo method with a focus on the evolution of domain structure and the magnetization in the equilibrium state. Our simulations can explain the effect of the pumping fluence on the recovery process. In particular, they reveal the importance of domain formation in the recently reported accumulation effect already found by the pump–probe magnetization hysteresis loop measurement of a metallic ferromagnetic film. In the framework of the model, it is predicted that by repeating pump pulses a sufficient number of times, the magnetization of the two-dimensional ferromagnetic system can be eliminated when the pump fluence is above a critical value.
Improvement of Surge Protection by Using an AlGaN/GaN-Based Metal–Semiconductor–Metal Two-Dimensional Electron Gas Varactor
Authors: Ferng Yi-Cherng , Chang Liann-Be , Das Atanu , Lin Ching-Chi , Cheng Chun-Yu , Kuei Ping-Yu , Chow Lee
Published: December 2012

In this paper, a varactor with metal–semiconductor–metal diodes on top of the (NH4)2S/P2S5-treated AlGaN/GaN two-dimensional electron gas epitaxial structure (MSM-2DEG) is proposed to the surge protection for the first time. The sulfur-treated MSM-2DEG varactor properties, including current–voltage (I–V), capacitance–voltage (C–V), and frequency response of the proposed surge protection circuit, are presented. To verify its capability of surge protection, we replace the metal oxide varistor (MOV) and resistor (R) in a state-of-the-art surge protection circuit with the sulfur-treated MSM-2DEG varactor under the application conditions of system-level surge tests. The measured results show that the proposed surge protection circuit, consisted of a gas discharge arrester (GDA) and a sulfur-treated MSM-2DEG varactor, can suppress an electromagnetic pulse (EMP) voltage of 4000 to 360 V, a reduction of 91%, whereas suppression is to 1780 V, a reduction of 55%, when using only a GDA.
Morphological Observations of Mesenchymal Stem Cell Adhesion to a Nanoperiodic-Structured Titanium Surface Patterned Using Femtosecond Laser Processing
Authors: Oya Kei , Aoki Shun , Shimomura Kazunori , Sugita Norihiko , Suzuki Kenji , Nakamura Norimasa , Fujie Hiromichi
Published: December 2012

It is known that the adhesive and anisotropic properties of cell-derived biomaterials are affected by micro- or nanoscale structures processed on culture surfaces. In the present study, the femtosecond laser processing technique was used to scan a laser beam at an intensity of approximately the ablation threshold level on a titanium surface for nanoscale processing. Microscopy observation revealed that the processed titanium exhibited a periodic-patterned groove structure at the surface; the width and depth of the groove were 292 ±50 and 99 ±31 nm, respectively, and the periodic pitch of the groove was 501 ±100 nm. Human synovium-derived mesenchymal stem cells were cultured on the surface at a cell density of 3.0×103cells/cm2after 4 cell passages. For comparison, the cells were also cultured on a nonprocessed titanium surface under the condition identical to that of the processed surface. Results revealed that the duration for cell attachment to the surface was markedly reduced on the processed titanium as compared with the nonprocessed titanium. Moreover, on the processed titanium, cell extension area significantly increased while cell orientation was aligned along the direction of the periodic grooves. These results suggest that the femtosecond laser processing improves the adhesive and anisotropic properties of cells by producing the nanoperiodic structure on titanium culture surfaces.
The Structure and Bonding State for Fullerene-Like Carbon Nitride Films with High Hardness Formed by Electron Cyclotron Resonance Plasma Sputtering
Authors: Kamata Tomoyuki , Niwa Osamu , Umemura Shigeru , Hirono Shigeru
Published: December 2012

We studied pure carbon films and carbon nitride (CN) films by using electron cyclotron resonance (ECR) sputtering. The main feature of this method is high density ion irradiation during deposition, which enables the pure carbon films to have fullerene-like (FL) structures without nitrogen incorporation. Furthermore, without substrate heating, the ECR sputtered CN films exhibited an enhanced FL microstructure and hardness comparable to that of diamond at intermediate nitrogen concentration. This microstructure consisted of bent and cross-linked graphene sheets where layered areas remarkably decreased due to increased sp3 bonding. Under high nitrogen concentration conditions, the CN films demonstrated extremely low hardness because nitrile bonding not only decreased the covalent-bonded two-dimensional hexagonal network but also annihilated the bonding there. By evaluating lattice images obtained by transmission electron microscopy and the bonding state measured by X-ray photoelectron spectroscopy, we classified the ECR sputtered CN films and offered phase diagram and structure zone diagram.
Formation of Thin Germanium Dioxide Film with a High-Quality Interface Using a Direct Neutral Beam Oxidation Process
Authors: Wada Akira , Zhang Rui , Takagi Shinichi , Samukawa Seiji
Published: December 2012

A damage-free and low-temperature neutral beam oxidation (NBO) process is used to directly form a thin germanium dioxide (GeO2) film. A GeO2 film with only a small amount of suboxide is formed even at a low substrate temperature of 300 °C because of the extremely low-activation-energy oxidation owing to bombardment with 5-eV-energy oxygen neutral beams. We combined the NBO process with hydrogen radical native oxide removal treatment to form high-quality GeO2 films, and our fabricated Al2O3/GeO2/Ge gate stack has an extremely low interface state density (D
it) of less than 1×1011 cm-2 eV-1.
Effect of Molecular Weight and Protection Ratio on Latent Image Fluctuation of Chemically Amplified Extreme Ultraviolet Resists
Authors: Kozawa Takahiro
Published: December 2012

Line edge roughness (LER) has been the most serious problem in the development of high-resolution lithography for manufacturing semiconductor devices. LER is caused by the stochastic effects in resist pattern formation. In this study, the effects of the molecular weight and protection ratio of a resist backbone polymer on latent image fluctuation were investigated by a Monte Carlo method. From the viewpoint of latent image fluctuation, a high molecular weight and a high protection ratio were found to be favorable for the reduction in LER.
Progress in Time-Resolved Photoemission Electron Microscopy at BL25SU, SPring-8: Radiofrequency Field Excitation of Magnetic Vortex Core Gyration
Authors: Ohkochi Takuo , Yamaguchi Akinobu , Kotsugi Masato , Hata Hiroshi , Goto Minori , Nozaki Yukio , Nakamura Tetsuya , Osawa Hitoshi , Kinoshita Toyohiko
Published: December 2012

We developed a system to carry out time-resolved photoemission electron microscopy under RF excitation at the BL25SU beamline in SPring-8. RF fields of up to ∼42 MHz could be applied to microsized magnetic disks with a power loss of less than 0.9 dB. We performed time-resolved real-space observations of the gyrotropic motion of the magnetic vortex core in Ni81Fe19 disks under an RF magnetic field. We confirmed that significant core gyrations can be seen only when the resonant frequency of the disks matches with the excitation frequency of the system.
Digest of ACM educational activities
Authors: Wilson Cameron , McGettrick Andrew , Timanovsky Yan
Published: December 2012

EduBits, your quarterly roundup of ACM educational activities, focuses on education policy and the way it affects the K--12 educational space. Cameron Wilson, Director of Public Policy for ACM, gives us a glimpse into the challenges of improving CS education throughout the U.S. He issues an important challenge to our community to get involved in K--12 scaling.
Fay
Authors: Erlingsson Úlfar , Peinado Marcus , Peter Simon , Budiu Mihai , Mainar-Ruiz Gloria
Published: December 2012

Fay is a flexible platform for the efficient collection, processing, and analysis of software execution traces. Fay provides dynamic tracing through use of runtime instrumentation and distributed aggregation within machines and across clusters. At the lowest level, Fay can be safely extended with new tracing primitives, including even untrusted, fully optimized machine code, and Fay can be applied to running user-mode or kernel-mode software without compromising system stability. At the highest level, Fay provides a unified, declarative means of specifying what events to trace, as well as the aggregation, processing, and analysis of those events.

We have implemented the Fay tracing platform for Windows and integrated it with two powerful, expressive systems for distributed programming. Our implementation is easy to use, can be applied to unmodified production systems, and provides primitives that allow the overhead of tracing to be greatly reduced, compared to previous dynamic tracing platforms. To show the generality of Fay tracing, we reimplement, in experiments, a range of tracing strategies and several custom mechanisms from existing tracing frameworks.

Fay shows that modern techniques for high-level querying and data-parallel processing of disagreggated data streams are well suited to comprehensive monitoring of software execution in distributed systems. Revisiting a lesson from the late 1960s [Deutsch and Grant 1971], Fay also demonstrates the efficiency and extensibility benefits of using safe, statically verified machine code as the basis for low-level execution tracing. Finally, Fay establishes that, by automatically deriving optimized query plans and code for safe extensions, the expressiveness and performance of high-level tracing queries can equal or even surpass that of specialized monitoring tools.
Frances
Authors: Sondag Tyler , Pokorny Kian L. , Rajan Hridesh
Published: December 2012

Students in all areas of computing require knowledge of the computing device including software implementation at the machine level. Several courses in computer science curricula address these low-level details such as computer architecture and assembly languages. For such courses, there are advantages to studying real architectures instead of simplified examples. However, real architectures and instruction sets introduce complexity that makes them difficult to grasp in a single semester course. Visualization techniques can help ease this burden, unfortunately existing tools are often difficult to use and consequently difficult to adopt in a course where time is already limited. To solve this problem, we present Frances. Frances graphically illustrates key differences between familiar high-level languages and unfamiliar low-level languages and also illustrates how familiar high-level programs behave on real architectures. Key to this tool is that we use a simple Web interface that requires no setup, easing course adoption hurdles. We also include several features that further enhance its usefulness in a classroom setting. These features include graphical relationships between high-level code and machine code, clearly illustrated step-by-step machine state transitions, color coding to make instruction behavior clear, and illustration of pointers. We have used Frances in courses and performed experimental evaluation. Our experiences with Frances in the classroom demonstrate its usability. Most notably, in our experimental setting, students with no computer architecture course experience were able to complete lessons using Frances with no guidance.