bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of Streptococcus pneumoniae Serotypes That Cause Parapneumonic Empyema in Turkey
Authors: Ceyhan Mehmet , Ozsurekci Yasemin , Gürler Nezahat , Ozkan Sengul , Sensoy Gulnar , Belet Nursen , Hacimustafaoglu Mustafa , Celebi Solmaz , Keser Melike , Dinleyici Ener Cagri , Alhan Emre , Baki Ali , Oner Ahmet Faik , Uzun Hakan , Kurugol Zafer , Aycan Ahmet Emre , Gurbuz Venhar , Karadag Oncel Eda , Celik Melda , Ozkaya Parlakay Aslinur
Published: May 2013

Streptococcus pneumoniaeis the most common etiological cause of complicated pneumonia, including empyema. In this study, we investigated the serotypes ofS. pneumoniaethat cause empyema in children. One hundred fifty-six children who were diagnosed with pneumonia complicated with empyema in 13 hospitals in seven geographic regions of Turkey between 2010 and 2012 were included in this study. Pleural fluid samples were collected by thoracentesis and tested for 14 serotypes/serogroups using a Bio-Plex multiplex antigen detection assay. The serotypes ofS. pneumoniaewere specified in 33 of 156 samples. The mean age ± the standard deviation of the 33 patients was 6.17 ± 3.54 years (range, 0.6 to 15 years). All of the children were unvaccinated according to the vaccination reports. Eighteen of the children were male, and 15 were female. The serotypes of the non-7-valent pneumococcal conjugated vaccine (non-PCV-7), serotype 1, serotype 5, and serotype 3, were detected in eight (14.5%), seven (12.7%), and five (9.1%) of the samples, respectively. Serotypes 1 and 5 were codetected in two samples. The remaining non-PCV-7 serotypes were 8 (n= 3), 18 (n= 1), 19A (n= 1), and 7F/A (n= 1). PCV-7 serotypes 6B, 9V, 14, 19F, and 23F were detected in nine (16.3%) of the samples. The potential serotype coverages of PCV-7, PCV-10, and PCV-13 were 16.3%, 45.4%, and 60%, respectively. Pediatric parapneumonic empyema continues to be an important health problem despite the introduction of conjugated pneumococcal vaccines. Active surveillance studies are needed to monitor the change inS. pneumoniaeserotypes that cause empyema in order to have a better selection of pneumococcal vaccines.
Comparison of a Real-Time PCR Method with Serology and Blood Smear Analysis for Diagnosis of Human Anaplasmosis: Importance of Infection Time Course for Optimal Test Utilization
Authors: Schotthoefer A. M. , Meece J. K. , Ivacic L. C. , Bertz P. D. , Zhang K. , Weiler T. , Uphoff T. S. , Fritsche T. R.
Published: May 2013

Anaplasmosis and ehrlichiosis are emerging tick-borne diseases with clinically similar presentations caused by closely related pathogens. Currently, laboratories rely predominantly on blood smear analysis (for the detection of intracellular morulae) and on serologic tests, both of which have recognized limitations, for diagnostic purposes. We compared the performance of a published real-time PCR assay that incorporates melt curve analysis to differentiate
Anaplasma
and
Ehrlichia
species with blood smear and serologic methods in an upper Midwest population. Overall, 38.5% of the specimens selected for evaluation had one or more tests that were positive for anaplasmosis. The PCR positivity for all specimens was maximal (21.2%; 29/137) during the early acute phase of illness (0 to 4 days since illness onset) and significantly less frequent (11.5%; 20/174) during later phases (>4 days since illness onset). All positive specimens were
Anaplasma phagocytophilum
; no
Ehrlichia
species were identified. The real-time PCR detected 100% of infections that were detected by blood smear analysis (14/14) and broadened the detection window from a maximum of 14 days for smear positivity to 30 days for PCR. Additional infections were detected by real-time PCR in 12.9% (11/85) of smear-negative patients. There was poor agreement between the real-time PCR assay and serologic test results: 19.8% (19/96) and 13.7% (29/212) of seropositive and -negative patients, respectively, were PCR positive. Seropositivity increased with increasing days of illness, demonstrating that serologic detection methods are best utilized during presumed convalescence. Our results indicate that the optimal performance and utilization of laboratory tests for the diagnosis of anaplasmosis require knowledge regarding time of symptom onset or days of illness.
Identification of Rare Pathogenic Bacteria in a Clinical Microbiology Laboratory: Impact of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry
Authors: Seng Piseth , Abat Cedric , Rolain Jean Marc , Colson Philippe , Lagier Jean-Christophe , Gouriet Frédérique , Fournier Pierre Edouard , Drancourt Michel , La Scola Bernard , Raoult Didier
Published: May 2013

During the past 5 years, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) has become a powerful tool for routine identification in many clinical laboratories. We analyzed our 11-year experience in routine identification of clinical isolates (40 months using MALDI-TOF MS and 91 months using conventional phenotypic identification [CPI]). Among the 286,842 clonal isolates, 284,899 isolates of 459 species were identified. The remaining 1,951 isolates were misidentified and required confirmation using a second phenotypic identification for 670 isolates and using a molecular technique for 1,273 isolates of 339 species. MALDI-TOF MS annually identified 112 species, i.e., 36 species/10,000 isolates, compared to 44 species, i.e., 19 species/10,000 isolates, for CPI. Only 50 isolates required second phenotypic identifications during the MALDI-TOF MS period (i.e., 4.5 reidentifications/10,000 isolates) compared with 620 isolates during the CPI period (i.e., 35.2/10,000 isolates). We identified 128 bacterial species rarely reported as human pathogens, including 48 using phenotypic techniques (22 using CPI and 37 using MALDI-TOF MS). Another 75 rare species were identified using molecular methods. MALDI-TOF MS reduced the time required for identification by 55-fold and 169-fold and the cost by 5-fold and 96-fold compared with CPI and gene sequencing, respectively. MALDI-TOF MS was a powerful tool not only for routine bacterial identification but also for identification of rare bacterial species implicated in human infectious diseases. The ability to rapidly identify bacterial species rarely described as pathogens in specific clinical specimens will help us to study the clinical burden resulting from the emergence of these species as human pathogens, and MALDI-TOF MS may be considered an alternative to molecular methods in clinical laboratories.
Identification of
cis
-Acting Nucleotides and a Structural Feature in West Nile Virus 3′-Terminus RNA That Facilitate Viral Minus Strand RNA Synthesis
Authors: Davis William G. , Basu Mausumi , Elrod Elizabeth J. , Germann Markus W. , Brinton Margo A.
Published: May 2013

The 3′-terminal nucleotides (nt) of West Nile virus (WNV) genomic RNA form a penultimate 16-nt small stem-loop (SSL) and an 80-nt terminal stem-loop (SL). These RNA structures are conserved in divergent flavivirus genomes. A previous
in vitro
study using truncated WNV 3′ RNA structures predicted a putative tertiary interaction between the 5′ side of the 3′-terminal SL and the loop of the SSL. Although substitution or deletion of the 3′ G (nt 87) within the SSL loop, which forms the only G-C pair in the predicted tertiary interaction, in a WNV infectious clone was lethal, a finding consistent with the involvement in a functionally relevant pseudoknot interaction, extensive mutagenesis of nucleotides in the terminal SL did not identify a
cis
-acting pairing partner for this SSL 3′ G. However, both the sequence and the structural context of two adjacent base pairs flanked by symmetrical internal loops in the 3′-terminal SL were shown to be required for efficient viral RNA replication. Nuclear magnetic resonance analysis confirmed the predicted SSL and SL structures but not the tertiary interaction. The SSL was previously reported to contain one of three eEF1A binding sites, and G87 in the SSL loop was shown to be involved in eEF1A binding. The nucleotides at the bottom part of the 3′-terminal SL switch between 3′ RNA-RNA and 3′-5′ RNA-RNA interactions. The data suggest that interaction of the 3′ SL RNA with eEF1A at three sites and a unique metastable structural feature may participate in regulating structural changes in the 3′-terminal SL.
Host IQGAP1 and Ebola Virus VP40 Interactions Facilitate Virus-Like Particle Egress
Authors: Lu Jianhong , Qu Yonggang , Liu Yuliang , Jambusaria Rakesh , Han Ziying , Ruthel Gordon , Freedman Bruce D. , Harty Ronald N.
Published: May 2013

We have identified host IQGAP1 as an interacting partner for Ebola virus (EBOV) VP40, and its expression is required for EBOV VP40 virus-like particle (VLP) budding. IQGAP1 is involved in actin cytoskeletal remodeling during cell migration and formation of filopodia. The physical interaction and the functional requirement for IQGAP1 in EBOV VP40 VLP egress link virus budding to the cytoskeletal remodeling machinery. Consequently, this interaction represents a novel target for development of therapeutics to block budding and transmission of filoviruses.
Prime/Boost Immunization with DNA and Adenoviral Vectors Protects from Hepatitis D Virus (HDV) Infection after Simultaneous Infection with HDV and Woodchuck Hepatitis Virus
Authors: Fiedler Melanie , Kosinska Anna , Schumann Alexandra , Brovko Olena , Walker Andreas , Lu Mengji , Johrden Lena , Mayer Anja , Wildner Oliver , Roggendorf Michael
Published: May 2013

Hepatitis D virus (HDV) superinfection of hepatitis B virus (HBV) carriers causes severe liver disease and a high rate of chronicity. Therefore, a vaccine protecting HBV carriers from HDV superinfection is needed. To protect from HDV infection an induction of virus-specific T cells is required, as antibodies to the two proteins of HDV, p24 and p27, do not neutralize the HBV-derived envelope of HDV. In mice, HDV-specific CD8+and CD4+T cell responses were induced by a DNA vaccine expressing HDV p27. In subsequent experiments, seven naive woodchucks were immunized with a DNA prime and adenoviral boost regimen prior to simultaneous woodchuck hepatitis virus (WHV) and HDV infection. Five of seven HDV-immunized woodchucks were protected against HDV infection, while acute self-limiting WHV infection occurred as expected. The two animals with the breakthrough had a shorter HDV viremia than the unvaccinated controls. The DNA prime and adenoviral vector boost vaccination protected woodchucks against HDV infection in the setting of simultaneous infection with WHV and HDV. In future experiments, the efficacy of this protocol to protect from HDV infection in the setting of HDV superinfection will need to be proven.
Structural Changes in Dengue Virus When Exposed to a Temperature of 37°C
Authors: Fibriansah Guntur , Ng Thiam-Seng , Kostyuchenko Victor A. , Lee Jaime , Lee Sumarlin , Wang Jiaqi , Lok Shee-Mei
Published: May 2013

Previous binding studies of antibodies that recognized a partially or fully hidden epitope suggest that insect cell-derived dengue virus undergoes structural changes at an elevated temperature. This was confirmed by our cryo-electron microscopy images of dengue virus incubated at 37°C, where viruses change their surface from smooth to rough. Here we present the cryo-electron microscopy structures of dengue virus at 37°C. Image analysis showed four classes of particles. The three-dimensional (3D) map of one of these classes, representing half of the imaged virus population, shows that the E protein shell has expanded and there is a hole at the 3-fold vertices. Fitting E protein structures into the map suggests that all of the interdimeric and some intradimeric E protein interactions are weakened. The accessibility of some previously found cryptic epitopes on this class of particles is discussed.
The Adenovirus L4-22K Protein Has Distinct Functions in the Posttranscriptional Regulation of Gene Expression and Encapsidation of the Viral Genome
Authors: Guimet Diana , Hearing Patrick
Published: May 2013

The adenovirus L4-22K protein is multifunctional and critical for different aspects of viral infection. Packaging of the viral genome into an empty capsid absolutely requires the L4-22K protein to bind to packaging sequences in cooperation with other viral proteins. Additionally, the L4-22K protein is important for the temporal switch from the early to late phase of infection by regulating both early and late gene expression. To better understand the molecular mechanisms of these key functions of the L4-22K protein, we focused our studies on the role of conserved pairs of cysteine and histidine residues in the C-terminal region of L4-22K. We found that mutation of the cysteine residues affected the production of infectious progeny virus but did not interfere with the ability of the L4-22K protein to regulate viral gene expression. These results demonstrate that these two functions of L4-22K may be uncoupled. Mutation of the histidine residues resulted in a mutant with a similar phenotype as a virus deficient in the L4-22K protein, where both viral genome packaging and viral gene expression patterns were disrupted. Interestingly, both mutant L4-22K proteins bound to adenovirus packaging sequences, indicating that the paired cysteine and histidine residues do not function as a zinc finger DNA binding motif. Our results reveal that the L4-22K protein controls viral gene expression at the posttranscriptional level and regulates the accumulation of the L4-33K protein, another critical viral regulator, at the level of alternative pre-mRNA splicing.
Impact of income inequality on life expectancy in a highly unequal developing country: the case of Brazil
Authors: Rasella Davide , Aquino Rosana , Barreto Mauricio Lima
Published: May 2013

Background

Few studies have analysed the effects of income inequality on health in developing countries, particularly during economic growth, reduction of social disparities and reinforcement of the welfare and healthcare system. We evaluated the association between income inequality and life expectancy in Brazil, including the effect of social and health interventions, in the period 2000–2009.

Methods

A panel dataset was created for the 27 Brazilian states over the referred time period. Multivariable linear regressions were performed using fixed-effects estimation with heteroscedasticity and serial correlation robust SEs. Models were fitted for life expectancy as a dependent variable, using the Gini index or a percentile income dispersion ratio as the main independent variable, and for demographic, socioeconomic and healthcare-related determinants as covariates.

Results

The Gini index, as the other measure of income inequality, was negatively associated with life expectancy (p<0.05), even after adjustment for all the socioeconomic and health-related covariates. The Family Health Program, the main primary healthcare (PHC) programme of the country, was positively associated with life expectancy (p<0.05).

Conclusions

In recent years, effective social policies have enabled Brazil to partially reduce absolute poverty and income inequality, contributing—together with PHC—to decreasing death rates in the population. Reducing income inequality may represent an important step towards improving health and increasing life expectancy, particularly in developing countries where inequalities are high.
Identification of a new reovirus causing substantial losses in broiler production in France, despite routine vaccination of breeders
Authors: Troxler S. , Rigomier P. , Bilic I. , Liebhart D. , Prokofieva I. , Robineau B. , Hess M.
Published: May 2013

Numerous cases of tenosynovitis appeared in France causing high morbidity in free‐range and standard broilers. The main clinical findings were lameness, stunting and non‐uniform bodyweights. Although the natural mortality was low, the economic losses due to birds that had to be removed from the flock prematurely, downgrading of carcases and lower average weights at slaughter were substantial. Postmortem examinations, bacteriological, virological and serological examination confirmed the aetiology of avian orthoreovirus (ARV)‐induced tenosynovitis. The isolated ARVs were analysed serologically and genetically. Sequencing of σC RT‐PCR products and phylogenetic analysis revealed a new type of ARV. The virus was not neutralised in serum neutralisation test using monovalent sera from vaccinated chickens. Together with the flock data, epidemiology of these recent reovirus outbreaks in France was reconstructed. It is concluded that these reovirus isolates differ serologically and genetically from the well described reovirus isolates used in commercial vaccines which were not capable of preventing the disease. The outbreaks resulted in substantial losses in broilers from vaccinated breeders.
Space–time diagram approach in derivation of Lienard–Wiechert potential for a moving point charge
Authors: Dikshit Biswaranjan
Published: May 2013

In classical electrodynamics, electric and magnetic fields at a point due to moving charges are calculated from the electric scalar potential and magnetic vector potential. For a moving point charge, this potential is known as Lienard–Wiechert potential and is derived in many different ways in textbooks. In this paper, we derive the retarded Lienard–Wiechert potential in a new graphical manner using space–time diagrams so that the derivation becomes more appealing and we can visualize the reason for the presence of an additional velocity-dependant factor in the denominator of the expression for the Lienard–Wiechert potential. The derivation is valid even for charged particles moving at relativistic speeds.
FINITE TIME BLOW UP OF FOURTH-ORDER WAVE EQUATIONS WITH NONLINEAR STRAIN AND SOURCE TERMS AT HIGH ENERGY LEVEL
Authors: SHEN JIHONG , YANG YANBING , CHEN SHAOHUA , XU RUNZHANG
Published: May 2013

In this paper, we study the initial boundary value problem for fourth-order wave equations with nonlinear strain and source terms at high energy level. We prove that, for certain initial data in the unstable set, the solution with arbitrarily positive initial energy blows up in finite time.
TWO-PION PRODUCTION IN ELECTRON-POLARIZED PROTON SCATTERING
Authors: AHMADOV A. I. , KURAEV E. A. , BYSTRITSKIY YU. M.
Published: May 2013

The process of two-pion production in the electron-polarized proton scattering is investigated. In the Weizsäcker–Williams approximation the differential spectral distributions and the spin-momentum correlations are considered. The spin correlation effects caused by ρ-meson widths are estimated to be of an order of several per cent. Both channels of the π+π- and π+π0 creation are considered. The effects of intermediate excited baryons are not considered. The spectral distributions on pion energy fractions in polarized and unpolarized cases are presented analytically and numerically.
TEXTURE ZEROS FOR DIRAC NEUTRINOS AND CURRENT EXPERIMENTAL TESTS
Authors: LIU XUE-WEN , ZHOU SHUN
Published: May 2013

The Daya Bay and RENO reactor neutrino experiments have revealed that the smallest neutrino mixing angle is in fact relatively large, i.e. θ13 ≈9°. Motivated by this exciting progress, we perform a systematic study of the neutrino mass matrix Mν with one or two texture zeros, in the assumption that neutrinos are Dirac particles. Among 15 possible patterns with two texture zeros, only three turn out to be favored by current neutrino oscillation data at the 3σ level. Although all the six patterns with one texture zero are compatible with the experimental data at the 3σ level, the parameter space of each pattern is strictly constrained. Phenomenological implications of Mν on the leptonic CP violation and neutrino mass spectrum are explored, and the stability of texture zeros against the radiative corrections is also discussed.
COMBINATORIAL KNOT FLOER HOMOLOGY AND DOUBLE BRANCHED COVERS
Authors: DOUROUDIAN FATEMEH
Published: May 2013

Using a Heegaard diagram for the pullback of a knot K ⊂ S3 in its double branched cover Σ2(K), we give a combinatorial proof for the invariance of the associated knot Floer homology over ℤ.
PERTURBED KEPLER PROBLEM IN GENERAL RELATIVITY WITH QUATERNIONS
Authors: NEMES F. , MIKÓCZI B.
Published: May 2013

The motion of binary star systems is re-examined in the presence of perturbations from the theory of general relativity. To handle the singularity of the Kepler problem, the equation of motion is regularized and linearized with quaternions. In this way first-order perturbation results are derived using the quaternion-based approach.
SHORT DISTANCE REPULSION AMONG BARYONS
Authors: AOKI SINYA , BALOG JANOS , DOI TAKUMI , INOUE TAKASHI , WEISZ PETER
Published: May 2013

We review recent investigations on the short distance behaviors of potentials among baryons, which are formulated through the Nambu–Bethe–Salpeter (NBS) wave function. After explaining the method to define the potentials, we analyze the short distance behavior of the NBS wave functions and the corresponding potentials by combining the operator product expansion (OPE) and a renormalization group (RG) analysis in the perturbation theory (PT) of QCD. These analytic results are compared with numerical results obtained in lattice QCD simulations.
NUMBER-PROJECTED ELECTRIC QUADRUPOLE MOMENTS OF EVEN–EVEN PROTON-RICH NUCLEI IN THE ISOVECTOR PAIRING CASE
Authors: DOUICI M. , ALLAL N. H. , FELLAH M. , BENHAMOUDA N. , OUDIH M. R.
Published: May 2013

An expression of the number-projected electric quadrupole moment Q2 has been established in the isovector pairing case using the SBCS discrete projection before variation method. It has been verified that this expression reduces to the pairing between like-particles one at the limit when the np pairing gap parameter Δ np goes to zero. The convergence of the projection method has been numerically tested and a fast convergence has been observed. The electric quadrupole moment has been numerically calculated for some even–even proton-rich nuclei such as 16 ≤ Z ≤ 56 and 0 ≤ (N-Z) ≤ 4. The single-particle energies and eigen-states used are those of a Woods–Saxon mean-field. The np pairing effect on Q2 has been studied either before and after the projection; it seems that it is somewhat small since the relative discrepancies do not exceed 12%. Moreover, the np pairing effect is roughly the same in both situations. However, it has been shown that this effect diminishes with increasing values of (N-Z). The projection effect on Q2 has also been studied when including, or not, the np pairing correlations. It appears that this effect is slightly less important in the np pairing case than when only the pairing between like-particles is considered.
A NOTE ON THE DOUBLE IMPACT ON CVA FOR CDS: WRONG-WAY RISK WITH STOCHASTIC RECOVERY
Authors: LI HUI
Published: May 2013

Current CVA modeling framework has ignored the impact of stochastic recovery rate. Due to the possible negative correlation between default and recovery rate, stochastic recovery rate could have a doubling effect on wrong-way risk. In the case of a payer CDS, when counterparty defaults, the CDS value could be higher due to default contagion while the recovery rate may also be lower if the economy is in a downturn. Using our recently proposed model of correlated stochastic recovery in the default time Gaussian copula framework, we demonstrate this double impact on wrong-way risk in the CVA calculation for a payer CDS. We also present a new form of Gaussian copula that correlates both default time and recovery rate.
ANALYTICAL PERTURBATION METHOD FOR CALCULATION OF SHELLS BASED ON 2D PADÉ APPROXIMANTS
Authors: ANDRIANOV IGOR VASIL'EVICH , OLEVS'KYY VICTOR ISAAKOVICH , AWREJCEWICZ JAN
Published: May 2013

Calculations of nonlinear displacements and vibrations of inhomogeneous loaded shells with developable principal surface by means of different analytical methods are represented. It is shown that solutions to these methods are the expansions of exact solution in the Taylor series for an independent variable, and in the particular case — for the powers of a natural parameter. A method that provides a polynomial asymptotic approximation of the exact solution of the general form and its meromorphic continuation based on 1D and 2D Padé approximations is proposed. Calculations of nonlinear deformation and stability of elastic flexible circular cylindrical shell under uniform external pressures and of free oscillations of simply supported stringer shell demonstrate the efficiency and accuracy of the proposed method.
ANALYSIS OF CHAOTIC VIBRATIONS OF FLEXIBLE PLATES USING FAST FOURIER TRANSFORMS AND WAVELETS
Authors: AWREJCEWICZ J. , KRYSKO A. V. , KUTEPOV I. E. , ZAGNIBORODA N. A. , ZHIGALOV M. V. , KRYSKO V. A.
Published: May 2013

In this paper chaotic vibrations of flexible plates of infinite length are studied. The Kirchhoff–Love hypotheses are used to derive the nondimensional partial differential equations governing the plate dynamics. The finite difference method (FDM) and finite element method (FEM) are applied to validate the numerical results. The numerical analysis includes both standard (time histories, fast Fourier Transform, phase portraits, Poincaré sections, Lyapunov exponents) as well as wavelet-based approaches. The latter one includes the so called Gauss 1, Gauss 8, Mexican Hat and Morlet wavelets. In particular, various plate dynamical regimes including the periodic, quasi-periodic, sub-harmonic, chaotic vibrations as well as bifurcations of the plate are illustrated and studied. In addition, the convergence of numerical results obtained via different wavelets is analyzed.
INVESTIGATION OF SELECTED MECHANICAL SYSTEMS BY RECURRENCE PLOTS METHOD
Authors: IWANIEC JOANNA
Published: May 2013

Recurrence of states, in the meaning that states are arbitrary close after some time, is a fundamental property of deterministic dynamical systems and is typical of nonlinear or chaotic systems. The main idea of the recurrence plots (RPs) method consists in revealing all the times when the phase space trajectory of the dynamical system visits roughly the same area in the phase space. Such recurrence of states is marked within a two-dimensional matrix with ones and zeros. Graphical representation of such a matrix is known in the literature as a recurrence plot. The paper concerns results of research into dynamic properties and determinism of selected mechanical systems. In order to analyze measured responses (time histories) of the considered systems with the use of the recurrence plots, the phase space of these systems was reconstructed by delay embedding. The smallest sufficient embedding dimensions were estimated with the use of the false nearest neighbors algorithm. For the purposes of time delay determining the method of mutual information function was used. All the necessary computations were performed with the use of the CRP Toolbox for MATLAB.
ON OSCILLATIONS OF AERODYNAMIC PENDULUM
Authors: SELYUTSKIY YURY D. , SAMSONOV VITALY A. , ANDRONOV PETR R.
Published: May 2013

Dynamics of an aerodynamic pendulum in steady airflow is studied using different modeling approaches: phenomenological model, where the unsteady effects are simulated using an oscillator attached to the pendulum, and modified method of discrete vortices (MMDV). It is shown that behavior of the pendulum according to the attached oscillator model agrees with data given by MMDV for a wide enough range of parameter values, and the applicability domain of the attached oscillator model is larger than that of the traditional quasi-steady approach. Stability of the "along the flow" equilibrium is studied depending on system parameters. It is shown, in particular, that this equilibrium loses its stability when the moment of inertia of the pendulum increases, if the rotation point is located in a certain range of distances upstream from the center of pressure.
VARIETY OF THE CASES OF INTEGRABILITY IN DYNAMICS OF A SYMMETRIC 2D-, 3D- AND 4D-RIGID BODY IN A NONCONSERVATIVE FIELD
Authors: SHAMOLIN MAXIM V.
Published: May 2013

A vast number of papers are devoted to studying the complete integrability of equations of four-dimensional rigid-body motion. Although in studying low-dimensional equations of motion of quite concrete (two- and three-dimensional) rigid bodies in a nonconservative force field, the author arrived at the idea of generalizing the equations to the case of a four-dimensional rigid body in an analogous nonconservative force field. As a result of such a generalization, the author obtained the variety of cases of integrability in the problem of body motion in a resisting medium that fills the four-dimensional space in the presence of a certain tracing force that allows one to reduce the order of the general system of dynamical equations of motion in a methodical way.
A COMPARATIVE STUDY OF SEISMIC STABILITY OF COUPLED ARCH DAM-FOUNDATION-RESERVOIR SYSTEMS USING INFINITE ELEMENTS AND VISCOUS BOUNDARY MODELS
Authors: HARIRI-ARDEBILI M. A. , MIRZABOZORG H.
Published: May 2013

In the present paper, a direct time domain procedure is used for dynamic structural stability analysis of the dam-reservoir-foundation coupled system in 3D space considering the impact of the ground motion duration. The foundation medium is assumed to be massed and infinite elements are used for modeling the semi-infinite medium of the foundation. The nonlinear behavior of mass concrete is modeled using the coaxial rotating smeared crack approach with the ability of cracking at Gaussian points. The reservoir is assumed to be compressible and is modeled using fluid finite elements. In order to investigate the effects of the ground motion duration on dynamic stability of the coupled system, a set of artificially-generated ground motions with different duration but the same intensities are used to analyze the system. It is found that the responses of the system with the massed foundation including either infinite elements or viscous boundary on the far-end face of the foundation are the same. Using the massless foundation leads to conservative stresses within dam body. Implementation of the infinite elements leads to decreasing crack profile of the concrete dam compared to the massless model; however higher duration ground motions lead to more damage in both models.
RELATIVE EQUILIBRIUM STATES AND DIMENSIONS OF FIBERWISE INVARIANT MEASURES FOR RANDOM DISTANCE EXPANDING MAPS
Authors: SIMMONS DAVID , URBAŃSKI MARIUSZ
Published: May 2013

We show that the Gibbs states (known from [10] to be unique) of Hölder continuous potentials and random distance expanding maps coincide with relative equilibrium states of those potentials, proving in particular that the latter exist and are unique. In the realm of conformal expanding random maps, we prove that given an ergodic (globally) invariant measure with a given marginal, for almost every fiber the corresponding conditional measure has dimension equal to the ratio of the relative metric entropy and the Lyapunov exponent. Finally we show that there is exactly one invariant measure whose conditional measures are of full dimension. It is the canonical Gibbs state.
INFORMATIONAL CONSTRAINTS-DRIVEN ORGANIZATION IN GOAL-DIRECTED BEHAVIOR
Authors: VAN DIJK SANDER G. , POLANI DANIEL
Published: May 2013

We study goal-directed behavior in the light of informationally constrained cognition. In a formal information-theoretical model, based on a description of goal-directed behavior as a family of Markov Decision Processes, we study lower bounds of constraints on the information about a goal needed to generate behavior that achieves such a goal at a certain level of optimality. We assume a working memory that operates on this minimally relevant goal information and study the necessary dynamics of in and out flow of information for such a working memory. Finally, we formally analyze explicit constraints on goal information pathways as information bottlenecks. Our results show that intrinsic and behavioral organizations, such as ritualized behavior, salient sub-goals, and natural abstractions, appear as a result of the studied informational constraints. We argue that a closed approach to generate a family of organizational concepts in a coherent way by systematically applying cognitive constraints as taken in this work can constitute an important step toward guiding self-organization.
(Invited) Challenges of Graphene Growth on Silicon Carbide
Authors: Yakimova Rositsa , Yazdi G. Reza , Iakimov Tihomir , Eriksson Jens , Darakchieva Vanya
Published: May 2013

One of the main challenges in the fabrication of device quality graphene is the achievement of large area monolayer graphene that is processing compatible. Here, the impact of the substrate properties on the thickness uniformity and electronic characteristics for epitaxial graphene on SiC produced by high temperature sublimation has been evidenced and discussed. Several powerful techniques have been used to collect data, among them large scale ellipsometry mapping has been demonstrated for the first time. The study is covering all three SiC polytype, e.g. 4H-, 6H- and 3C-SiC in order to reveal eventual peculiarities that have to be controlled during graphene growth. The advantage of the cubic polytype is unambiguously demonstrated.
(Invited) Graphene Nanoribbon Growth and Dual-Gated Graphene Transistors
Authors: Sato Shintaro , Hayashi Kenjiro , Nakaharai Shu , Yokoyama Naoki
Published: May 2013

We first describe self-organizing graphene ribbon formation by chemical vapor deposition. Graphene ribbons can be formed only on narrow twin crystal regions with a (001) or high-index surface sandwiched between Cu crystals having (111) surfaces. At a relatively low CH4 pressure in Ar/H2, graphene is preferentially nucleated and formed on twin crystals. The preferential nucleation is probably caused by a difference in surface-dependent adsorption energies of reactants. In the second part, we describe newly developed dual-gated graphene transistors. We found that a transistor with a graphene channel irradiated with He ions can have a transport gap up to 380 meV. We then made dual-gated transistors using such a channel and obtained an on-off ratio of 103 at 200 K. The device has a channel region between the dual gates, and the polarity of the transistor can be electrostatically reversed by flipping the bias polarity of one of the dual gates.
(Invited) InGaSb MOSFET Channel on Metamorphic Buffer: Materials, Interfaces and Process Options
Authors: Greene Andrew , Madisetti Shailesh , Nagaiah P. , Tokranov Vadim , Yakimov Michael , Moore R. , Oktyabrsky Serge
Published: May 2013

High quality bulk GaSb and InGaSb quantum wells grown on GaAs substrates were MBE grown using a AlGaSb(As) metamorphic buffer layers to reduce dislocation density down to 107cm-2. Strained In0.36Ga0.64Sb quantum wells with a biaxial compressive strain of 1.8% showed the highest mobility of 1020 cm2/Vs and a low sheet resistance of 3.9 kΩ/sq. at hole sheet at hole density of 1.9x1012 cm-2. Buried channel design with an AlGaSb top barrier improved hole mobility by only 30% compared to surface QW channels. Improving the interface trap density down to 1012 cm-2eV-1 was realized using an amorphous Si layer (in-situ gate oxide) or an InAs layer (ex-situ gate) as a gate passivation. p++-GaSb epitaxial contact layers were developed and showed the leakage current of ~0.1 mA/cm2 not affected by growth defects. Critical elements of "gate-last" InGaSb MOSFET fabrication process were developed utilizing an InAs etch stop layer to avoid high temperature processing of the gate stack.
(Invited) Structural and Optical Properties of Si/Ge Nanowire Heterojunctions
Authors: Tsybeskov Leonid , Chang H.-Y. , Mala Selina , Kamins Ted I. , Wu Xiaohua , Lockwood David J.
Published: May 2013

In crystalline, dislocation-free, Si/Ge nanowire (NW) axial heterojunctions grown using the vapor-liquid-solid (VLS) technique, transmission electron microscopy (TEM) photoluminescence (PL) and Raman spectroscopy reveal a SiGe alloy transition layer with preferential chemical composition and strain. In addition to the lattice mismatch, strain due to the difference in Si and Ge thermal expansion is observed. We find, in agreement with theoretical predictions, that the strain can be partially relived by lateral nanowire expansion in the vicinity of the Si/Ge heterojunction. In addition to the observed nanowire lateral expansion, the lattice mismatched induced strain could be relaxed by other mechanisms including intermixing, formation of structural defects and partial amorphization. The conclusions are supported by analytical TEM measurements.
Semi-Metal Nanowire Transistors from First Principle Calculations
Authors: Ansari Lida , Fagas Giorgos , Greer James C.
Published: May 2013

Bandgap engineering in semimetal nanowires can be utilized to form a field effect transistor (FET) near atomic dimensions and eliminates the need for doping in the transistor’s source, channel, or drain. For sufficiently small wire diameters the metallic behaviour of the semimetal is lost and a bandgap is induced. Using a full quantum mechanical description of the semi metal nanowires, we are able to demonstrate that the design of adopant-free, mono material confinement modulated gap transistors (CMGT) which unlike conventional FETs does not require dopant atoms to define different device regions. This overcomes a primary obstacle to fabricating sub-5 nm transistors, enabling aggressive scaling to near atomic limits.
Effect of Moisture on Electrical and Reliability Characteristics for Dense and Porous Low-k Dielectrics
Authors: Cheng Yi-Lung , Huang Jun-Fu , Chang Wei-Yuan , Chang Yu-Min , Leu Jihperng (Jim)
Published: May 2013

The effect of absorbed moisture on the electrical and reliability characteristics of the low-k dielectrics was investigated in this study. The experimental results indicate that the porous low-k dielectrics would absorb more moisture as compared to the dense low-k dielectrics. This absorbed moisture degrades the electrical and reliability performance of the low-k dielectrics. A higher temperature anneals at 400oC is needed to decompose physically-adsorbed water, which is benefit to restore reliability performance. On the other hand, the chemically-adsorbed moisture seems to be difficult to be removed by a 400oC annealing, causing a degraded TDDB performance.
Gold-Free InAlN/GaN Schottky Gate HEMT On Si (111) Substrate with ZrO2 Passivation
Authors: Kyaw Lwin Min , Liu Yi , Bera Milan Kumar , Ngoo Yi Jie , Tripathy Sudhiranjan , Chor Eng Fong
Published: May 2013

The electrical properties of Ti/Al/Ni/W (25/200/50/100 nm) ohmic contact and Ni/W (350/50 nm) Schottky contact to InAlN/GaN HEMT grown on high resistive Si (111) substrate are reported in this study. The specific contact resistivity of Ti/Al/Ni/W contacts has been investigated as a function of annealing temperature and Ti/Al thickness ratio, and has achieved the lowest value of 1.06×10-6 Ω∙cm2 after annealing at 900 oC in vacuum. The maximum Schottky barrier height of the Ni/W (350/50 nm) contact achieved is 0.72 eV at room temperature. With ZrO2 passviation, the InAlN/GaN-on-Si HEMT exhibits a higher extrinsic transconductance of 160 mS/mm (by ~33.3%) and a lower on-resistance of 10 Ω/mm (by ~16.7%) than that without passivation.
Nonradiative Recombination Mechanism in Phosphor-Free GaN-Based Nanowire White Light Emitting Diodes and the effect of Ammonium Sulfide Surface Passivation
Authors: Nguyen Hieu Pham Trung , Djavid Mehrdad , Mi Zetian
Published: May 2013

We report on a detailed investigation of nonradiative recombination processes in InGaN/GaN dot-in-a-wire white light emitting diodes (LEDs) grown by molecular beam epitaxy. It is observed that, for such nanowire LEDs, the peak quantum efficiency occurs at relatively high injection current levels of >100 A/cm2, compared to those of conventional InGaN/GaN quantum well blue LEDs. Through detailed simulation studies, it is concluded that, Shockley-Read-Hall nonradiative recombination, due to the presence of surface states and defects, plays a dominant role on the nanowire LED performance. We have further shown that such nonradiative recombination can be greatly reduced when the nanowire LEDs are treated by ammonium sulfide solution ((NH4)2Sx, 40-48% concentration), which can lead to a much faster increasing trend of quantum efficiency vs. injection current, compared to the unpassivated devices.
InGaN LEDs Grown on Patterned Sapphire Substrates with Modified Top-Tip Cone Shapes
Authors: Hsueh Hsu-Hung , Ou Sin-Liang , Cheng Chiao-Yang , Wuu Dong-Sing , Horng Ray-Hua
Published: May 2013

The GaN-based light emitting diodes (LEDs) were grown on the cone-shaped patterned sapphire substrates (PSSs) by metal-organic chemical vapor deposition. To enhance the epilayer quality and optoelectronic performance of LEDs, the PSSs were further wet etched to form the modified top-tip cone shapes. After the wet etching process, some dry-etched induced damage on sapphire surface generated in the PSS fabrication process could be removed, leading to a higher crystal quality in epilayer and better device performance. As the wet etching time was increased to 3 min, the LED grown on the cone-shaped PSS had 53% and 8% improvement in light output (@ 20 mA) compared to that on conventional sapphire substrate (CSS) and the cone-shaped PSS without wet etching, respectively. It indicates that the technique of the modification in PSS shape has a high potential in LEDs application.
Electrodeposited Wide-Bandgap Semiconducting ZnO and CuSCN Thin Films and Nanowires for Interface Engineering of Polymer Solar Cells
Authors: Chappaz-Gillot Cyril , Berson Solenn , Sanchez Sylvia , Salazar Raul , Lechêne Balthazar , Aldakov Dmitry , Delaye Vincent , Guillerez Stéphane , Ivanova Valentina
Published: May 2013

The polymer solar cells (PSCs) have been developed as a promising low-cost renewable energy. The best PSC is composed of a polymer donor layer and a fullerene acceptor bulk-heterojunction (BHJ) composite sandwiched between a transparent conductive oxide, and a metal electrode. In this manuscript we report on the integration of the electrodeposited ZnO and CuSCN in PSCs as electron (ETL) and hole (HTL) transporting layers. We developed inverted polymeric photovoltaic devices based on electrodeposited ZnO ETL with power conversion efficiency (PCE) of 3.3% on glass substrates and remarkably good stability under AM1.5 illumination for an active surface area of 0.28 cm2. Electrodeposited CuSCN nanowires are proposed as new HTL in conventional PSCs and a PCE of 5.1% with low-bandgap polymer active layer was obtained. The appropriate selection of the ETL and the HTL and the method for their preparation is crucial to obtain high-performance of PSCs.
Very Low Electron Density in Undoped Enhancement-Mode Si/SiGe Two-Dimensional Electron Gases with Thin SiGe Cap Layers
Authors: Huang Chiao-Ti , Li Jiun-Yun , Sturm James C.
Published: May 2013

We report the lowest electron density (4.9×1010 cm-2 and 1.1×1011 cm-2) and high mobility (~400,000 cm2/Vs and ~200,000 cm2/Vs) of undoped enhancement-mode Si/SiGe two-dimensional electron gases comparing to samples previously reported with similar thin SiGe cap thickness (55nm and 27nm). The dominant scattering mechanism over a wide range of two-dimensional electron density in both samples is the scattering from remote charges at oxide/silicon interface. In addition, a clear metal-insulator transition is observed in the sample with a 27-nm SiGe cap.
Evaluation of Stress Induced by Plasma Assisted ALD SiN Film
Authors: Nagata Kohki , Nagasaka Masaya , Yamaguchi Takuya , Ogura Atsushi , Oji Hiroshi , Son Jin-Young , Hirosawa Ichiro , Watanabe Y. , Hirota Y.
Published: May 2013

Stresses characteristic induced by silicon nitride thin film formed using plasma assisted atomic layer deposition were investigated. SiN films were deposited using batch-type ALD equipment. Stresses were evaluated by UV-Raman spectroscopy, and SiN densities and chemical bonding states were evaluated by X-ray reflectometry and hard X-ray photoelectron spectroscopy, respectively. The stresses induced by SiN films were influenced by the film density and chemical bonding states. It could be controlled by optimization of process temperature. In addition, thermal stability and in-plane fluctuation of stress were also discussed. It was indicated that P-ALD technique has high in-plane uniformity of stress and higher stress comparing with conventional thermal ALD.
Deposited ALD SiO2 High-k/Metal Gate Interface for High Voltage Analog and I/O Devices on Next Generation Alternative Channels and FINFET Device Structures
Authors: Siddiqui Shahab , Chowdhury Murshed M , Brodsky Maryjane , Rahim Nilufa , Dai Min , Krishnan Siddarth , Fugardi Steve , Wu Ernest , Chou Anthony , Narasimha Shreesh , Li Jinghong , Mcstay Kevin , Linder Barry , Maciejewski Edward , Rettmann Ryan , Mittl Steven , Kwon Unoh , Narayanan Vijay , Henson William , Schepis Dominic , Chudzik Michael
Published: May 2013

A highly reliable SiO2 deposited by atomic layer deposition (ALD) as a gate dielectric interface layer with high-k/metal gate (HKMG) in high voltage I/O field effect transistor (FETs) for advanced technologies has been demonstrated. Improved process control, better gate oxide conformality, superior dielectric reliability (over CVD SiO2), and equivalent uniformity and reliability compared to thermal oxide proves its usefulness for FinFET/ETSOI I/O devices. In addition, use of ALD SiO2 with novel interface layer results in reduced interfacial regrowth on SiGe channel, which when coupled with post deposition nitridation and annealing optimization for optimal performance, is an attractive oxide optimization option for alternate channel architectures.
A Study of Polysilicon Gate Etch Uniformity in 300 mm Silicon Wafers
Authors: Lau Wai Shing , Yang Peizhen , Siah Soh Yun
Published: May 2013

Experimental data show that the polysilicon gate length tends to be smaller in the middle of the silicon wafer and also at the silicon wafer edge. This can be seen from electrical measurement data of MOS transistors in a row along a diameter of the wafer. In-line CD (critical dimension) data will also be presented to support the above claim. Physical mechanisms responsible for the experimental observation will be provided. Possible existence of plasma instability during the polysilicon gate etch process will also be discussed.
Visualization of Plasma Etching Damage of Si Using Room Temperature Spectroscopic Photoluminescence
Authors: Jang Jian Shiu-Ko , Jeng Chih-Cherng , Wang Ting-Chun , Huang Chih-Mu , Wang Ying-Lang , Yoo Woo Sik
Published: May 2013

Room temperature photoluminescence (RTPL) spectroscopy was proposed as an in-line plasma-induced-damage (PID) visualization technique. As an application example, ~200 and ~600 nm thick oxide films on 300 mm wafers (SiO2/Si) grown by plasma enhanced chemical deposition (PECVD) were plasma etched under different etching and bias radio frequency (RF) power conditions. Oxide etch rate, oxide uniformity and RTPL spectra/intensity were measured and characterized under three excitation wavelengths (532, 650 and 827 nm) with different probing depths. A distinct pattern of PIDs was observed representative of showerhead patterns, common to a typical plasma etching system. Visualization of PIDs was successfully done by multiwavelength RTPL spectroscopy.