bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of virtual resistor in power electronic converter on subsynchronous oscillation damping
Authors: Rizqiawan Arwindra , Fujita Goro , Funabashi Toshihisa , Nomura Masakatsu
Published: October 2011

Virtual impedance concept provides the impedance effects without need to put real physically impedance in the circuit. In power system, oscillation will not occur as long as the impedance seen by turbine‐generator set is ‘passive’. In order to ensure the impedance is seen as ‘passive’ by the turbine‐generator set, a series resistor can be placed in the system. This paper proposes implementation of virtual resistor concept in grid connected power electronic converter to replaced the aforementioned series resistor, then analyze its impact on subsynchronous oscillation phenomena. It can be shown that virtual resistor can improve the negative region of converter input admittance. Moreover, it also gives us better damping in system involving grid connected inverter. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Design of PSO‐based fuzzy logic controller for single axis magnetic levitation system
Authors: Hussein Basheer Noaman , Sulaiman Nasri , Raja Ahmad R. K. , Marhaban Mohammad Hamiruce
Published: October 2011

In this paper, a particle swarm optimization (PSO) method is proposed to design an optimal robust fuzzy logic controller (FLC). The objective of this paper is to design a nonlinear optimal robust controller for the single axis magnetic levitation system with high accuracy. PSO algorithm is applied to search globally optimal parameters of FLCs. Three different FLCs are designed. First, proportional derivative (PD)‐like FLC. Second, the FLC is based on the PSO algorithm to find the optimal range of the eight linguistic membership functions (FLC1 with PSO algorithm). Finally, the FLC is based on the PSO algorithm to find the optimal range and shape of the four linguistic membership functions (FLC2 with PSO algorithm). The performances of three different FLCs are compared. Simulation results show that PSO‐based optimal FLCs find the optimal range and shape of the four linguistic membership functions and achieved better performance than the other proposed controllers, minimizing 48 fuzzy rules. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Attenuation of low dose methylmercury and glutamate induced‐cytotoxicity and tau phosphorylation by an N‐methyl‐D‐aspartate antagonist in human neuroblastoma (SHSY5Y) cells
Authors: Petroni Daniel , Tsai Jeffrey , Mondal Debasis , George William
Published: October 2011

Methylmercury (MeHg), a known neurotoxin, has been reported to alter glutamate homeostasis in the neuronal environment resulting in excitotoxicity. This study was conducted to investigate whether, and if so, under what conditions, that low dose MeHg would enhance the toxicity of glutamate and to what extent that blockade of NMDA receptors would alter MeHg and glutamate's toxicity in cultured neuroblastoma cells. Neuroblastoma cells (SH‐SY5Y) were used in a cell culture model to study effects of MeHg, glutamate (glu), a calcium chelator (BAPTA‐AM), and a noncompetitive NMDA antagonist, MK‐801 on cell growth, cell survival, and phosphorylation of tau protein, as a measure of cellular events associated with tauopathies. Exposure of cells to a combination of MeHg (50 nM) and glutamate (1 mM) resulted in both a greater decrease in cell viability as well as a greater induction in tau phosphorylation, as compared to exposures with MeHg and glutamate alone. MK‐801, an NMDA receptor antagonist, and the intracellular calcium chelator, BAPTA‐AM, both significantly inhibited tau hyperphosphorylation and protected cells from the effects of combination exposures to glutamate and MeHg. These results may indicate that exposure to even nontoxic levels of MeHg may prime neuronal cells to be more susceptible to neuronal injury from excitotoxicants such as glutamate and thus may increase the likelihood of neurological disease states. In conclusion, low‐dose MeHg‐induced toxicity may be related to an increase in the cellular response to glutamate and that NMDA receptor antagonists may provide a potential treatment for MeHg‐associated neurological diseases. © 2011 Wiley Periodicals, Inc. Environ Toxicol 28: 700–706, 2013.
Photocatalytic TiO2 films deposited by different methods
Authors: Vergöhl Michael , Althues Holger , Frach Peter , Glöß Daniel , Graumann Tobias , Hübner Christof , Neumann Frank , Neubert Thomas , Schottner Gerhard , Song Do‐Keun
Published: October 2011

Photocatalytic TiO2 layers are deposited with different methods available within the Fraunhofer Photocatalysis Alliance. These are: Magnetron sputtering, evaporation, sol‐gel, laquer coating, and CVD. The photocatalytic activity under UV illumination is determined by decomposition of stearic acid. The optical properties of the films are compared and discussed.
Ionenstrahlpolieren von feinoptischen Substraten
Authors: Nestler Matthias , Demmler Marcel , Zeuner Michael , Kiontke Sven
Published: October 2011

Die steigenden Anforderungen an die Polierfehlerkorrektur in der Optikindustrie führen zur Entwicklung von innovativen Anlagenkonzepten, die den hohen Standards gerecht werden und gleichzeitig effektive Durchsatzraten gewährleisten.

Die Autoren dieses Artikels präsentieren ein fortschrittliches neues Anlagensystem für den kommerziellen Optikmarkt, welches anlagentechnische Neuerungen mit einem ausgefeilten Prozessfluss verbindet. Einsparungen von unnötigen mechanischen Komponenten, der Einsatz einer Doppelschleuse und ein modifizierbarer Strahldurchmesser führen zu einer Bearbeitungsgenauigkeit besser als λ/50. Das Anlagensystem eignet sich für diverse Materialien in der Herstellung von optischen Bauteilen mit sphärischen und asphärischen Konturen sowie jeglichen Freiformflächen und ist mit einer eigens dafür entwickelten Software ausgestattet. [1]
The Northeast Arran Trough, the Corrie conundrum and the Highland Boundary Fault in the Firth of Clyde, SW Scotland
Authors: YOUNG G. M. , CALDWELL W. G. E.
Published: October 2011

Two strikingly different successions of Lower Carboniferous (mainly Tournaisian) sedimentary rocks are closely juxtaposed on the NE coast of the island of Arran, SW Scotland. Near the village of Corrie a thin succession (~ 17 m) of Tournaisian rocks is preserved, whereas in the neighbouring Fallen Rocks–Laggan area, correlative rocks are > 300 m in thickness. These contrasting successions are separated by the Laggan Fault, which is a landward extension of the submarine Brodick Bay Fault, marking the SW boundary of the Northeast Arran Trough. The contrasting thickness and stratigraphy of the two sequences of sedimentary rocks result from juxtaposition of shoulder and trough deposits along the Laggan–Brodick Bay Fault. Although originally a normal, basin-defining fault, later sinistral movements caused significant displacement of the NE Arran Trough, together with a segment of the Highland Boundary Fault, from their original positions. The most northerly occurrence of the Highland Boundary Fault on Arran is thought to be the truncated northern end of the Corloch Fault. To the SW the surface trace of the Highland Boundary Fault is largely obscured by a Palaeogene granite body but it is present on the west side of the island, near Dougrie. The Highland Boundary Fault appears to be displaced to the south, in Kilbrannan Sound, by a series of NW-trending sinistral transcurrent faults. Thus the ‘anomalous’ trend of the Highland Boundary Fault and narrowing of the Midland Valley of Scotland in the Firth of Clyde area may be explained by later fault movements and intrusion of the Palaeogene North Arran Granite Pluton.
Development of multiple-locus variable-number tandem-repeat analysis for rapid genotyping ofEhrlichia ruminantiumand its application to infectedAmblyomma variegatumcollected in heartwater endemic areas in Uganda
Authors: NAKAO RYO , MORRISON LIAM J. , ZHOU LIJIA , MAGONA JOSEPH W. , JONGEJAN FRANS , SUGIMOTO CHIHIRO
Published: October 2011

The rickettsial bacteriumEhrlichia ruminantiumis the causative agent of heartwater, a serious tick-borne disease in ruminants. The genetic diversity of organisms in the field will have implications for cross-protective capacities of any vaccine developed, and for an effective vaccine design strategy proper genotyping and understanding of existing genetic diversity in the field is necessary. We searched for variable-number tandem-repeat (VNTR) loci for use in a multi-locus VNTR analysis (MLVA). Sequencing analysis of 30 potential VNTRs using a panel of 17 reference strains from geographically diverse origins identified 12 VNTRs with allelic profiles differing between strains. Application of MLVA to 38E. ruminantium-infectedAmblyomma variegatumcollected from indigenous cattle in 6 different districts of Uganda identified 21 MLVA types. The discriminatory power of MLVA was greater than that ofmap1PCR-restriction fragment length polymorphism analysis, with which only 6 genotypes were obtained. The high discriminatory power as well as cost- effective performance of MLVA provide the potential for this technique to be applied in the future with respect to optimizing vaccine trials by identifying local strain diversity, and also raise the possibility of exploring the association betweenE. ruminantiumgenotypes and phenotypes such as pathological outcome in the ruminant host.
Digital platform-based multi-domain virtual prototype simulation on a high-speed parallel manipulator
Authors: Zhiyong Yang , Wenhao Feng , Jiang Wu , Tian Huang
Published: October 2011

This paper presents how to build an all-digital co-simulation platform of a mechtronic system so as to reduce the burden and error of system modeling. In the construction of a platform, a driving system, including a motor, a pulse-width modulation (PWM) and a controller, is simulated using Matlab/Simulink. The behavior of the mechanism is analyzed using the ADAMS software. By the proper interface function for the real-time communication between two parts of the models, a virtual working environment is established. Finally, a proportional integral derivative (PID) controller verifies the validity of the digital platform.
Carlson varieties and Chouinard's theorem
Authors: Andrews Robert C.
Published: October 2011

Chouinard, in [8], proved the following remarkable result.

Theorem. Let k be a field of characteristic p and G be any finite group. Then a (finitely generated left) kG-module is protective if and only if it is free on restriction to all the elementary abelian p-subgroups of G.
A model in which countable Fréchet α1-spaces are first countable
Authors: Dow Alan , Steprans Juris
Published: October 2011

Although this paper is concerned with answering a question in general topology about sequential convergence, the techniques used may be of greater interest to those interested in the structure of filters on ω. A point in a topological space is called an α1-point if whenever is a countable family of sequences converging to it, there is a sequence B, also converging to it, such that A\B is finite for each A ∈ . A space is α1 if each point of the space is an α1-point. Nyikos has shown that the existence of countable Fréchet α1-spaces which are not first countable follows from the assumption and has asked if it is consistent that no such space exists. It is not difficult to see that if there is an α1-space which is not first countable the there is also one with only one non-isolated point. Since, in answering Nyikos' question, we are only concerned with countable spaces, it follows that we are really dealing with certain types of filters on ω. The precise translation of the topological question to a filter theoretic one is contained in §2. The reader who is not interested in the details may wish to read only §2, the first half of §3 and §5.
A Tauberian theorem concerning Dirichlet series
Authors: Borwein David
Published: October 2011

It is shown that under certain general Tauberian conditions the asymptotic relationship

between two Dirichlet series implies the asymptotic relationship
Kasparov's technical lemma for b*-algebras
Authors: Hennings M. A.
Published: October 2011

It is found that Kasparov's technical lemma may be proved for b*-algebras by a generalization of the techniques used in recent proofs for the C*-algebra case. An application of this result enables us to prove a standard lifting problem for b*-algebras.
Metric Diophantine approximation and Hausdorff dimension on manifolds
Authors: Dodson M. M. , Rynne B. P. , Vickers J. A. G.
Published: October 2011

In this paper we discuss homogeneous Diophantine approximation of points on smooth manifolds M in ℝk. We begin with a brief survey of the notation and results. For any x,y ∈ℝk, let

.
A large deviation local limit theorem
Authors: Doney R. A.
Published: October 2011

The following elegant one-sided large deviation result is given by S. V. Nagaev in [2].

Theorem 0. Suppose that {Sn,n ≤ 0} is a random walk whose increments Xi are independent copies of X, where(X) = 0 and

Pr{X > x} ̃ x−αL(x) as x→ + ∞,

and where 1 < α < ∞ and L is slowly varying at ∞. Then for any ε > 0 and uniformly in x ≥ εn

Pr{Sn > x} ̃ n Pr{X > x} as n→∞.

It is the purpose of this note to point out that for lattice-valued random walks there is an analogous local limit theorem.
SOWING THE BLOOD WITH THE MAIZE: ZAPOTEC EFFIGY VESSELS AND AGRICULTURAL RITUAL
Authors: Sellen Adam T.
Published: October 2011

This paper examines how maize and blood were central elements in ancient Zapotec religious practices and how they were conceptually linked. I analyze the iconography of different types of Classic period Zapotec ceramic effigy vessels. Using a comparative approach, I identify elements that frequently appear on the urns, such as maize plants in different stages of growth, or representations of the milpa. Framing these observations with early colonial historical accounts and ethnographic studies, I suggest that the main theme involved in these ancient representations was fertility, maintained by a sacred pact forged between humans and their deities that required sacrifice through bloodletting. The drawing and offering of blood insured a cycle of sustained and abundant growth for their most important crop: maize. Though many advances have been made in recent years regarding Zapotec iconography, I will offer some new interpretations regarding specific forms represented on the urns.
SHIFTING PATTERNS OF OBSIDIAN EXCHANGE IN POSTCLASSIC OAXACA, MEXICO
Authors: Levine Marc N. , Joyce Arthur A. , Glascock Michael D.
Published: October 2011

In this paper, we present a diachronic analysis of obsidian procurement patterns during the Postclassic period in the Lower Río Verde region of Oaxaca. The study is based on x-ray fluorescence (XRF) and visual analysis of obsidian artifacts from excavated household contexts at Early Postclassic (a.d.800–1100) Río Viejo and Late Postclassic (a.d.1100–1522) Tututepec (Yucu Dzaa). We report the presence of at least six sources of obsidian imported to the lower Río Verde region in the Early Postclassic, whereas during the fourteenth and fifteenth centuries of the Late Postclassic, the local assemblage was dominated by obsidian from Pico de Orizaba and Pachuca. Changes in obsidian procurement patterns in the lower Río Verde region through time are interpreted in light of sociopolitical change at the local, regional, and macroregional scales. The study represents the most detailed analysis of Postclassic period obsidian exchange yet reported from Oaxaca.
KEEPING ABREAST OF THE MAYA: A STUDY OF THE FEMALE BODY IN MAYA ART
Authors: Stone Andrea J.
Published: October 2011

This paper discusses the importance of female breasts in gender construction in Maya art and explains artistic conventions and choices in their deployment. The visual analysis focuses on Late Classic pictorial vases and ceramic figurines. Rather than reflecting a natural body, the female breast was filtered through a cultural lens that drove its highly conceptual rendering in Maya art, mirrored in a breast hieroglyph. Through the principle of contrast, including morphology and absence vs. presence of breasts in specific pictorial contexts, Maya artists constructed female personae varying in age, class, supernatural status, and gender ambiguity. In order to flesh out the layered meaning of the breast, the paper turns to ethnographic studies of modern Maya medicine concerning the hot-cold system. It is argued that ethnographic data on women's bodies in medical discourse shed light on how the breast served as an index of age-based female stereotypes.
Plünnecke's Inequality
Authors: PETRIDIS GIORGIS
Published: October 2011

Plünnecke's inequality is a standard tool for obtaining estimates on the cardinality of sumsets and has many applications in additive combinatorics. We present a new proof. The main novelty is that the proof is completed with no reference to Menger's theorem or Cartesian products of graphs. We also investigate the sharpness of the inequality and show that it can be sharp for arbitrarily long, but not for infinite commutative graphs. A key step in our investigation is the construction of arbitrarily long regular commutative graphs. Lastly we prove a necessary condition for the inequality to be attained.
Direct Stimulation of Angiotensin II Type 2 Receptor Enhances Spatial Memory
Authors: Jing Fei , Mogi Masaki , Sakata Akiko , Iwanami Jun , Tsukuda Kana , Ohshima Kousei , Min Li-Juan , Steckelings Ulrike M , Unger Thomas , Dahlöf Björn , Horiuchi Masatsugu
Published: October 2011

We examined the possibility that direct stimulation of the angiotensin II type 2 (AT2) receptor by a newly generated direct AT2 receptor agonist, Compound 21 (C21), enhances cognitive function. Treatment with C21 intraperitoneal injection for 2 weeks significantly enhanced cognitive function evaluated by the Morris water maze test in C57BL6 mice, but this effect was not observed in AT2 receptor-deficient mice. However, C21-induced cognitive enhancement in C57BL6 mice was attenuated by coadministration of icatibant, a bradykinin B2 receptor antagonist. Administration of C21 dose dependently increased cerebral blood flow assessed by laser speckle flowmetry and hippocampal field-excitatory postsynaptic potential (f-EPSP) determined by electrophysiological techniques in C57BL6 mice. Furthermore, activation of the AT2 receptor by C21 promoted neurite outgrowth of cultured hippocampal neurons prepared from fetal transgenic mice expressing green fluorescent protein. Finally, we investigated the pathologic relevance of C21 for spatial learning using an Alzheimer's disease mouse model with intracerebroventricular injection of amyloid-β (1 to 40). We observed that treatment with C21 prevented cognitive decline in this model. These results suggest that a direct AT2 receptor agonist, C21, enhances cognitive function at least owing to an increase in CBF, enhancement of f-EPSP, and neurite outgrowth in hippocampal neurons.
Lack of Neuroprotection of Inhibitory Peptides Targeting Jun/JNK after Transient Focal Cerebral Ischemia in Spontaneously Hypertensive Rats
Authors: Gow William R , Campbell Kym , Meade Amanda J , Watt Paul M , Milech Nadia , Knuckey Neville W , Meloni Bruno P
Published: October 2011

In this study, we have assessed the ability of two TAT-fused peptides PYC36d-TAT and JNKI-1d-TAT (JNKI-1 or XG-102), which respectively inhibit jun proto-oncogene (c-Jun) and c-Jun N-terminal kinase (JNK) activation, to reduce infarct volume and improve functional outcome (adhesive tape removal) after transient focal cerebral ischemia in Spontaneously Hypertensive (SH) rats. PYC36d-TAT and JNKI-1d-TAT peptide batches used for experiments were tested in vitro and protected cortical neurons against glutamate excitotoxicity. Rats were treated intravenously with three different doses of PYC36d-TAT (7.7, 76, or 255 nmol/kg), JNKI-1d-TAT (255 nmol/kg), d-TAT peptide (255 nmol/kg), or saline (vehicle control), 10 minutes after reperfusion after 90 minutes of middle cerebral artery occlusion (MCAO). Contrary to other stroke models, no treatment significantly reduced infarct volume or improved functional score measurements compared with vehicle-treated animals when assessed 48 hours after MCAO. Additionally, assessment of the JNKI-1d-TAT peptide, when administered 1 or 2 hours after reperfusion after 90 minutes of MCAO, also did not improve histological or functional outcomes at 48 hours after occlusion. This study is the first to evaluate the efficacy of PYC36d-TAT and JNKI-1d-TAT using the SH rat, which has recently been shown to be more sensitive to AMPA receptor activation rather than to NMDA receptor activation after cerebral ischemia, and which may have contributed to the negative findings.
Visualization of co-localization in Aβ42-administered neuroblastoma cells reveals lysosome damage and autophagosome accumulation related to cell death
Authors: Soura Violetta , Stewart-Parker Maris , Williams Thomas L. , Ratnayaka Arjuna , Atherton Joe , Gorringe Kirsti , Tuffin Jack , Darwent Elisabeth , Rambaran Roma , Klein William , Lacor Pascale , Staras Kevin , Thorpe Julian , Serpell Louise C.
Published: October 2011

Aβ42 [amyloid-β peptide-(1–42)] plays a central role in Alzheimer's disease and is known to have a detrimental effect on neuronal cell function and survival when assembled into an oligomeric form. In the present study we show that administration of freshly prepared Aβ42 oligomers to a neuroblastoma (SH-SY5Y) cell line results in a reduction in survival, and that Aβ42 enters the cells prior to cell death. Immunoconfocal and immunogold electron microscopy reveal the path of the Aβ42 with time through the endosomal system and shows that it accumulates in lysosomes. A 24 h incubation with Aβ results in cells that have damaged lysosomes showing signs of enzyme leakage, accumulate autophagic vacuoles and exhibit severely disrupted nuclei. Endogenous Aβ is evident in the cells and the results of the present study suggest that the addition of Aβ oligomers disrupts a crucial balance in Aβ conformation and concentration inside neuronal cells, resulting in catastrophic effects on cellular function and, ultimately, in cell death.
Stepwise proteolytic activation of type I procollagen to collagen within the secretory pathway of tendon fibroblasts in situ
Authors: Canty-Laird Elizabeth G. , Lu Yinhui , Kadler Karl E.
Published: October 2011

Proteolytic cleavage of procollagen I to collagen I is essential for the formation of collagen fibrils in the extracellular matrix of vertebrate tissues. Procollagen is cleaved by the procollagen N- and C-proteinases, which remove the respective N- and C-propeptides from procollagen. Procollagen processing is initiated within the secretory pathway in tendon fibroblasts, which are adept in assembling an ordered extracellular matrix of collagen fibrils in vivo. It was thought that intracellular processing was restricted to the TGN (trans-Golgi network). In the present study, brefeldin A treatment of tendon explant cultures showed that N-proteinase activity is present in the resulting fused ER (endoplasmic reticulum)–Golgi compartment, but that C-proteinase activity is restricted to the TGN in embryonic chick tendon fibroblasts. In late embryonic and postnatal rat tail and postnatal mouse tail tendon, C-proteinase activity was detected in TGN and pre-TGN compartments. Preventing activation of the procollagen N- and C-proteinases with the furin inhibitor Dec-RVKR-CMK (decanoyl-Arg-Val-Lys-Arg-chloromethylketone) indicated that only a fraction of intracellular procollagen cleavage was mediated by newly activated proteinases. In conclusion, the N-propeptides are removed earlier in the secretory pathway than the C-propeptides. The removal of the C-propeptides in post-Golgi compartments most probably indicates preparation of collagen molecules for fibril formation at the cell–matrix interface.
β2‐Adrenergic receptor‐induced transactivation of epidermal growth factor receptor and platelet‐derived growth factor receptor via Src kinase promotes rat cardiomyocyte survival
Authors: Chen Hao , Ma Ning , Xia Jing , Liu Jinfen , Xu Zhiwei
Published: October 2011

Chronic stimulation of the β‐AR (adrenergic receptor) promotes apoptosis of cardiomyocytes, which is implicated in cardiac dysfunction. β1‐AR and β2‐AR are the main subtypes of β‐AR that exert distinct effects on the survival of cardiomyocytes. To clarify the physiological roles of β1‐AR and β2‐AR in cardiomyocytes, the effects of β1‐AR or β2‐AR knockdown on the survival of H9c2 cardiomyocytes was investigated. Knockdown of β2‐AR, but not β1‐AR, suppressed the phosphorylation of EGFR (epidermal growth factor receptor) and PDGFR (platelet‐derived growth factor receptor) induced by ISO (isoprenaline). The EGFR inhibitor, AG1478, attenuated ERK (extracellular‐signal‐regulated kinase) activation and partially decreased cell survival. Pretreatment with AG1296, a PDGFR inhibitor, abolished ISO‐induced Akt (also known as protein kinase B) phosphorylation and led to a decrease in cell viability. In addition, the Src tyrosine kinase inhibitor, PP2, blocked ISO‐mediated both Akt and ERK activation and heavily suppressed viability. Accordingly, in primary neonatal rat cardiomyocytes, the β2‐AR inhibitor, but not the β1‐AR inhibitor, abrogated the transactivation of EGFR and PDGFR, which was respectively related to Akt and ERK activation. The results show that β2‐AR transactivates PDGFR and EGFR, thereby promoting survival of cardiomyocytes.
Possible interaction between B1 retrotransposon‐containing sequences and βmajor globin gene transcriptional activation during MEL cell erythroid differentiation
Authors: Vizirianakis Ioannis S. , Tezias Sotirios S. , Amanatiadou Elsa P. , Tsiftsoglou Asterios S.
Published: October 2011

Repetitive sequences consist of >50% of mammalian genomic DNAs and among these SINEs (short interspersed nuclear elements), e.g. B1 elements, account for 8% of the mouse genome. In an effort to delineate the molecular mechanism(s) involved in the blockade of the in vitro differentiation program of MEL (murine erythroleukaemia) cells by treatment with methylation inhibitors, we detected a DNA region of 559 bp in chromosome 7 located downstream of the 3′‐end of the βmajor globin gene (designated B1‐559) with unique characteristics. We have fully characterized this B1‐559 region that includes a B1 element, several repeats of ATG initiation codons and consensus DNA‐binding sites for erythroid‐specific transcription factors NF‐E2 (nuclear factor‐erythroid‐derived 2), GATA‐1 and EKLF (erythroid Krüppel‐like factor). Fragments derived from B1‐559 incubated with nuclear extracts form protein complexes in both undifferentiated and differentiated MEL cells. Transient reporter‐gene experiments in MEL and human erythroleukaemia K‐562 cells with recombinant constructs containing B1‐559 fragments linked to HS‐2 (hypersensitive site‐2) sequences of human β‐globin gene LCR (locus control region) indicated potential cooperation upon erythropoiesis and globin gene expression. The possible interaction between the B1‐559 region and βmajor globin gene transcriptional activation upon execution of erythroid MEL cell differentiation programme is discussed.
Low-frequency modes of the benzoic acid dimer in chloroform observed by the optical Kerr effect
Authors: Yamaguchi Sayuri , Mazur Kamila , Heisler Ismael A. , Shirota Hideaki , Tominaga Keisuke , Meech Stephen R.
Published: October 2011

The low frequency Raman spectral density associated with the intermolecular hydrogen-bonding interaction of benzoic acid in chloroform was investigated through the ultrafast optically-heterodyne-detected optical Kerr effect. The low-frequency solute Raman spectrum was obtained by Fourier transform analysis and subtraction of the solvent spectrum from the solution spectrum. The resulting difference spectrum has a broad band below 150 cm−1 with a peak at around 80 cm−1. Previous studies of aromatic liquids suggest that the origin of such a low-frequency band is librational motion, although intermolecular hydrogen-bonding modes in benzoic acid may also contribute. To clarify these contributions to the low-frequency band, methyl benzoate was used to estimate the librational component; its structure is similar to benzoic acid, but it forms no intermolecular hydrogen bonds. Both librational and intermolecular modes were found to contribute to the low-frequency Raman spectrum of the dimer and thus can be separated. These experimental results were compared with the results of density functional theory calculations. In addition, the effect of deuteration on the Raman spectrum was also investigated.
Stresses in bi-material GaN assemblies
Authors: Suhir E.
Published: October 2011

Simple, easy-to-use, and physically meaningful analytical (“mathematical”) models are suggested for the assessment of the lattice- and thermal-mismatch stresses in bi-material semiconductor, and particularly GaN, assemblies. The developed models are used to evaluate and to compare these two types of stresses. It is concluded that, unless specially pre-engineered substrates are employed, even if a reasonably good lattice match takes place (as, e.g., in the case of a GaN film fabricated on a SiC substrate, when the lattice-mismatch strain is only about 3%), the lattice-mismatch stresses are still considerably higher than the thermal stresses. This is true even when the temperature change from the semiconductor growth temperature to a low (operation or testing) temperature is significant, and the thermal stresses are, therefore, the highest. The developed models can be used, before the actual experimentation and/or fabrication is carried out, to assess the merits and shortcomings of a particular GaN or another semiconductor crystal growth technology, as far as the expected stresses are concerned.
Efficient generation of fast ions from surface modulated nanostructure targets irradiated by high intensity short-pulse lasers
Authors: Andreev Alexander , Kumar Naveen , Platonov Konstantin , Pukhov Alexander
Published: October 2011

It’s shown that the imposition of sub-laser wavelength relief structures on the surface of mass-limited-targets results into several folds higher short-pulse laser absorption, and consequently the efficient generation of fast ions. The optimum relief parameters for enhanced short-pulse laser absorption and higher ion acceleration are estimated numerically by particle-in-cell simulations and then corroborated by analytical scalings. The stability of the pre-imposed surface modulation during the laser pulse foil interaction is also examined.
Thermal transport in double-wall carbon nanotubes using heat pulse
Authors: Chen Liang , Kumar Satish
Published: October 2011

Multi-wall carbon nanotubes (MWCNTs) are outstanding materials for diverse applications such as electrodes, interconnects, or thermal management. Deep understanding of the underlying thermal transport mechanism in MWCNTs is crucial to engineer their thermal properties for a specific application. This paper investigates the interfacial thermal interaction in double-wall carbon nanotubes (DWCNTs) using molecular dynamics simulation and compares the transport in DWCNT with that in single-wall carbon nanotubes (SWCNTs). The present study is based on the application of intense heat pulse in the middle of the CNTs and analysis of wavelike responses of energy propagation as well as the kinetic energy corresponding to the velocity components in the radial, tangential, and longitudinal directions of CNTs. The analysis shows that the leading wave packets corresponding to the tangential and longitudinal components propagate ballistically along the tube, while the radial components show diffusive behavior with slow propagation speed. However, the radial components can efficiently transfer energy between tubes of DWCNTs while the fast moving longitudinal components and tangential components are weak in the interfacial energy transfer. An appropriate understanding of the energy exchange between different layers of tubes will pave the path of the future design of MWCNT based pellets and composites.
Core size dependence of the confinement energies, barrier heights, and hole lifetimes in Ge-core/Si-shell nanocrystals
Authors: Neupane Mahesh R. , Lake Roger K. , Rahman Rajib
Published: October 2011

The effect of the Ge core size on the confinement energies, barrier heights, and hole lifetimes in spherical Ge/Si core-shell nanocrystals is studied using an atomistic, tight-binding model with an sp3d5s* basis including spin-orbit coupling. Nanocrystal diameters range from 11 nm to 17.5 nm with Ge core diameters ranging from 1 nm to 7.5 nm. With a Ge core diameter of ~4 nm, and a Si shell thickness of ≥3 nm, the thermionic barrier presented by the Si shell increases the hole lifetime by a factor of ~2×108 compared to the hole lifetime in an all-Si nanocrystal in SiO2. A retention lifetime of 10 years is obtained with a 3 nm Ge core and a 3 nm Si shell with a 3 nm SiO2 tunnel oxide.
Analysis of interfacial peeling in IC chip pick-up process
Authors: Peng Bo , Huang YongAn , Yin ZhouPing , Xiong YouLun
Published: October 2011

The IC chip–ejecting and pick-up process plays a critical role in advanced packages since the success ratio and productivity are determined by the delamination of the chip-on-substrate structure. The paper investigates analytically the interfacial peeling mechanism of a chip-on-substrate structure subjected to a transverse concentrated load resulting from ejecting needle from the fracture mechanics point of view. The effects of key factors, including chip size, initial crack length, and substrate material, are uncovered. Finite element calculations are performed to obtain the interfacial peeling energy-release rate by using virtual crack-closure technique with dummy nodes. Analytical formulas and numerical results match fairly well for the entire range of the chip length and the crack length. It is shown that the greater the ratio of length to thickness of the chip is, the smaller the energy-release rate is, and length is the more important factor than thickness to affect the peeling. It implies the interfacial peeling gets tougher for thin or big chips during the pick-up process. Second, as the crack grows, the peeling energy-release rate increases. Third, the softer the substrate is, the greater the peeling energy-release rate is under the action of a constant transverse load. For the pick-up of thin or big chips, in order to achieve high success rate and suppress damage to the chip, it is suggested that more compliant and thinner substrate be adopted, weaker adhesive strength be chosen, and multiple needles be used.
A simple profile-fitting method to determine the metastable and resonant densities in a cold atmospheric pressure argon plasma jet
Authors: Xiong Q. , Nikiforov A. , Britun N. , Snyders R. , Leys C. , Lu X.
Published: October 2011

A simple profile-fitting method is applied to determine the concentrations of metastable and resonant species in a cold atmospheric pressure argon plasma jet. This method is based on the analysis of the effect of self-absorption broadening on the profiles of spectral lines emitted from plasma. The Argon lines which correspond to transitions to metastable and resonant lower states were measured with high resolution optical emission spectroscopy. Fitting the measured line contours yields line-integrated densities (Nl × L) of metastable Ar(1s5) and Ar(1s3) of 1.2 × 1015 m−2 and 5.0 × 1014 m−2, respectively. For resonant species, it is difficult to perform a good density-estimation by fitting measured line contours because of the broad intrinsic resonant line shape and the low resonant densities in the plasma. Top-limits of 4.8 × 1015 m−2 and 7.2 × 1014 m−2 are estimated for resonant states Ar(1s2) and Ar(1s4), respectively. By comparing the fittings of metastable and resonant lines, it is found that the applicability of the profile-fitting routine is sensitive to the line-center optical thickness of emission lines (mainly determined by the lower states densities) and the sharpness of intrinsic line profiles of corresponding transitions.
Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge
Authors: Li Shou-Zhe , Wu Qi , Yan Wen , Wang Dezhen , Uhm Han S.
Published: October 2011

An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O2/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.
Microwave diagnostics of femtosecond laser-generated plasma filaments
Authors: Papeer J. , Mitchell C. , Penano J. , Ehrlich Y. , Sprangle P. , Zigler A.
Published: October 2011

We present a simple non-intrusive experimental method allowing a complete single shot temporal measurement of laser produced plasma filament conductivity. The method is based on filament interaction with low intensity microwave radiation in a rectangular waveguide. The suggested diagnostics allow a complete single shot temporal analysis of filament plasma decay with resolution better than 0.3 ns and high spatial resolution along the filament. The experimental results are compared to numerical simulations, and an initial electron density of 7 × 1016 cm−3 and decay time of 3 ns are obtained.
Thermodynamic study of benzocaine insertion into different lipid bilayers
Authors: Cascales J. J. López , Costa S. D. Oliveira , Porasso R. D.
Published: October 2011

Despite the general consensus concerning the role played by sodium channels in the molecular mechanism of local anesthetics, the potency of anaesthetic drugs also seems to be related with their solubility in lipid bilayers. In this respect, this work represents a thermodynamic study of benzocaine insertion into lipid bilayers of different compositions by means of molecular dynamics simulation. Thus, the free energy profiles associated with benzocaine insertion into symmetric lipid bilayers composed of different proportions of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylserine were studied. From the simulation results, a maximum in the free energy (ΔG) profile was measured in the region of the lipid/solution interface. This free energy barrier appears to be very much dependent on the lipid composition of the membrane. On the other hand, the minimum free energy (ΔG) within the bilayer remained almost independent of the lipid composition of the bilayer. By repeating the study at different temperatures, it was seen how the spontaneity of benzocaine insertion into the lipid bilayer is due to an increase in the entropy associated with the process.
Computational study of the interaction of indole-like molecules with water and hydrogen sulfide
Authors: Cabaleiro-Lago Enrique M. , Rodríguez-Otero Jesús , Peña-Gallego Ángeles
Published: October 2011

The characteristics of the interaction between water and hydrogen sulfide with indole and a series of analogs obtained by substituting the NH group of indole by different heteroatoms have been studied by means of ab initio calculations. In all cases, minima were found corresponding to structures where water and hydrogen sulfide interact by means of X–H···π contacts. The interaction energies for all these π complexes are quite similar, spanning from −13.5 to −18.8 kJ/mol, and exhibiting the stability sequence NH > CH2 ≈ PH > Se ≈ S > O, for both water and hydrogen sulfide. Though interaction energies are similar, hydrogen sulfide complexes are slightly favored over their water counterparts when interacting with the π cloud. σ-Type complexes were also considered for the systems studied, but only in the case of water complexes this kind of complexes is relevant. Only for complexes formed by water and indole, a significantly more stable σ-type complex was found with an interaction energy amounting to −23.6 kJ/mol. Oxygen and phosphorous derivatives also form σ-type complexes of similar stability as that observed for π ones. Despite the similar interaction energies exhibited by complexes with water and hydrogen sulfide, the nature of the interaction is very different. For π complexes with water the main contributions to the interaction energy are electrostatic and dispersive contributing with similar amounts, though slightly more from electrostatics. On the contrary, in hydrogen sulfide complexes dispersion is by far the main stabilizing contribution. For the σ-type complexes, the interaction is clearly dominated by the electrostatic contribution, especially in the indole-water complex.
Behavior of nitrogen atoms in SiC-SiO2 interfaces studied by electrically detected magnetic resonance
Authors: Umeda T. , Esaki K. , Kosugi R. , Fukuda K. , Ohshima T. , Morishita N. , Isoya J.
Published: October 2011

The microscopic behavior of nitrogen atoms in the SiO2-SiC interface regions of n-channel lateral 4 H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs) was studied using low-temperature electrically detected magnetic resonance spectroscopy and other techniques. The results show that nitrogen atoms eliminated shallow interface states observable at 20 K and further diffused into the channel region of the MOSFETs as shallow donors. These two behaviors enable nitrogen atoms to change the channel conductivity of SiC MOSFETs.
Q-switching in the electron backward-wave oscillator
Authors: Denisov G. G. , Kuzikov S. V. , Savilov A. V.
Published: October 2011

The use of Q-switching (periodical modulation of the feedback factor) is proposed for the electron backward-wave oscillator (BWO). This can be a way to realize regimes of a stable generation of periodical short high-power rf pulses with relatively high averaged efficiency. As compared to the conventional regime of the stable generation of a BWO with no feedback, in the Q-switched BWO the averaged electronic efficiency can be increased by an order of magnitude, whereas the peak power of output rf pulses is 40–50 times higher.
Secondary instability as cause of minor disruptions in density limit tokamak plasmas
Authors: Salzedas F. ,   JET EFDA Contributors
Published: October 2011

Experimental evidence was found in JET plasmas of a new instability at the onset of minor disruptions. This instability is observed during the growth of the well known m/n = 2/1 magnetic island and is localized close to it, behaving as a secondary instability to the island. The large heat fluxes towards the plasma edge, characteristic of minor disruptions, occur during the low rotation phase of the magnetic island at a time the amplitude of the secondary instability suffers a large increase. No poloidal or toroidal mode numbers could be assigned to the secondary instability.
Intrinsic and extrinsic dielectric responses of CaCu3Ti4O12 thin films
Authors: Rubinger C. P. L. , Moreira R. L. , Ribeiro G. M. , Matinaga F. M. , Autier Laurent S. , Mercey B. , Lobo R. P. S. M.
Published: October 2011

CaCu3Ti4O12 thin films were epitaxially grown on (001) LaAlO3 substrates by pulsed laser deposition under optimized growth conditions. The crystal structure and sample morphology were characterized by x-ray diffraction, AFM, TEM, ellipsometry, and Raman spectroscopy. The dielectric responses of the films were investigated in a large temperature range (5 to 375 K) by infrared reflectivity and impedance spectroscopies. The films exhibited a colossal dielectric response, with the dielectric permittivity reaching 104 at 100 Hz. The results obtained in a broad frequency range allowed us to investigate the behavior of intrinsic and extrinsic dielectric responses of this material. The room temperature centrosymmetrical cubic structure remains stable down to 5 K, though softening of the lower frequency infrared phonon modes indicates an incipient ferroelectric character. The radio frequency dielectric response reveals two relaxations of extrinsic origin, a primary higher frequency relaxation responsible for the colossal dielectric behavior and a secondary one of lower frequency. The activation energies of these processes are compatible with the presence of shallow defect levels created by oxygen vacancies.
Angle-resolved cathodoluminescence spectroscopy
Authors: Coenen Toon , Vesseur Ernst Jan R. , Polman Albert
Published: October 2011

We present a cathodoluminescence spectroscopy technique which combines deep subwavelength excitation resolution with angle-resolved detection capabilities. The cathodoluminescence emission is collected by a paraboloid mirror (effective NA = 0.96) and is projected onto a 2D CCD array. The azimuthal and polar emission pattern is directly deduced from the image. As proof of principle, we use the technique to measure the angular distribution of transition radiation from a single crystalline gold surface under 30 keV electron irradiation. We find that the experiment matches very well with theory, illustrating the potential of this technique for the characterization of photonic structures with deep subwavelength dimensions.
Elastic stiffness of single-crystalline FeSe measured by picosecond ultrasonics
Authors: Wen Yu-Chieh , Liao Yang-Chung , Chang Hsian-Hong , Mok Boon-How , Lee Yung-Chi , Huang Tzu-Wen , Yeh Kuo-Wei , Luo Jiu-Yong , Wang Ming-Jye , Sun Chi-Kuang , Wu Maw-Kuen
Published: October 2011

We report investigations on the elasticity of superconducting FeSe using picosecond ultrasonic technique. The tetragonal (001) FeSe thin film, deposited on a processed SrTiO3 substrate by the pulsed laser deposition, exhibits distinct c-axis preferred orientation and single-crystalline features as a result of the x-ray diffraction. The high-quality crystallinity thus enables quantitative examinations of anisotropic stiffness coefficients (C33) of FeSe, correlating to the interatomic interaction in the simplest iron-based superconductor. Our experiment indicates a room-temperature C33 of 40.9 ± 0.4 GPa and material stiffening of 4.3% at low temperatures, which can be explained by the weakening of anharmonic phonon–phonon interactions.
Dynamics near the threshold for blowup in the one-dimensional focusing nonlinear Klein-Gordon equation
Authors: Bizoń Piotr , Chmaj Tadeusz , Szpak Nikodem
Published: October 2011

We study dynamics near the threshold for blowup in the focusing nonlinear Klein-Gordon equation utt − uxx + u − |u|2αu = 0 on the line. Using mixed numerical and analytical methods we find that solutions starting from even initial data, fine-tuned to the threshold, are trapped by the static solution S for intermediate times. The details of trapping are shown to depend on the power α, namely, we observe fast convergence to S for α > 1, slow convergence for α = 1, and very slow (if any) convergence for 0 < α < 1. Our findings are complementary with respect to the recent rigorous analysis of the same problem (for α > 2) by Krieger, Nakanishi, and Schlag [“Global dynamics above from the ground state energy for the one-dimensional NLKG equation,” preprint arXiv:1011.1776 [math.AP]].
Quantum anomalous Hall effect in doped ternary chalcogenide topological insulators TlBiTe2 and TlBiSe2
Authors: Niu Chengwang , Dai Ying , Yu Lin , Guo Meng , Ma Yandong , Huang Baibiao
Published: October 2011

Ternary Chalcogenide TlBiTe2 and TlBiSe2 have been proved to be promising topological insulators. In the present work, the occurrence of quantum anomalous Hall effect for a model Hamiltonian with ferromagnetic order is predicted. The first-principle calculations reveal that Cr is the best candidate to induce the ferromagnetic order in the insulating phase among X (X = Ti, Cr, Fe, and Au). The magnetic order in insulating phase arises from the spin polarization of substitutional Cr atoms and the free carriers are not needed for the formation of the substantial ferromagnetic coupling. These are very significant for the dissipationless devices in spintronics.