bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Genotypes of Influenza B Viruses Cocirculated in Taiwan in 2004 and 2005
Authors: Chen Guang-Wu , Shih Shin-Ru , Hsiao Mei-Ren , Chang Shih-Cheng , Lin Shu-Hung , Sun Chien-Fen , Tsao Kuo-Chien
Published: March 2007

An influenza B outbreak occurred in Taiwan in 2004 and 2005, during which both Victoria (Vic) and Yamagata (Ya) lineages cocirculated. This study examined 36 influenza B viral genomes isolated during the outbreak to reveal their reassortment patterns. According to the isolate groupings in phylogenetic analysis, we were able to categorize those 36 isolates as being of either the Victoria or Yamagata lineage for all eight influenza B virus genomic segments, except for the NS gene, in which clades A and B existed. Based on these groupings, three genome patterns clearly emerged, namely, pattern I (Vic+Vic+Ya+Vic+Ya+Ya+Ya+A, from segments 1 to 8), pattern II (Ya+Ya+Ya+Ya+Ya+Ya+Ya+B), and pattern III (Ya+Ya+Ya+Ya+Ya+Ya+Ya+A). According to the timeline of those isolates under investigation, it appears that pattern I and II viruses could have generated pattern III via reassortment of the NS gene. On the other hand, a genomewide comparison of all six pattern III Taiwanese viruses with 37 international influenza B viral genomes showed that two international strains, B/Oslo/71/04 and B/England/23/04, were consistently clustered with the pattern III viruses isolated in Taiwan in 2004 and 2005, suggesting that Taiwanese pattern III viruses might also have been imported due to their matching genomic composition.
CD81 Expression Is Important for the Permissiveness of Huh7 Cell Clones for Heterogeneous Hepatitis C Virus Infection
Authors: Akazawa Daisuke , Date Tomoko , Morikawa Kenichi , Murayama Asako , Miyamoto Michiko , Kaga Minako , Barth Heidi , Baumert Thomas F. , Dubuisson Jean , Wakita Takaji
Published: March 2007

Huh7 cells constitute a permissive cell line for cell culture of hepatitis C virus (HCV) particles. However, our Huh7 line shows limited permissiveness for HCV. Thus, in this study we set out to determine which host factors are important for conferring permissiveness. To analyze the limited permissiveness of our Huh7 cells, 70 clones were obtained after single-cell cloning of parental Huh7 cells. The cloned Huh7 cells exhibited various levels of HCV pseudoparticles and JFH-1 virus infection efficiency, and some clones were not permissive. A subgenomic replicon was then transfected into the cloned Huh7 cells. While the replication efficiencies differed among the cloned Huh7 cells, these efficiencies did not correlate with infectious permissibility. Flow cytometry showed that CD81, scavenger receptor class B type I, and low-density-lipoprotein receptor expression on the cell surfaces of the Huh7 clones differed among the clones. Interestingly, we found that all of the permissive cell clones expressed CD81 while the nonpermissive cell clones did not. To confirm the importance of CD81 expression for HCV permissiveness, CD81 was then transiently and stably expressed on a nonpermissive Huh7 cell clone, which was consequently restored to HCV infection permissiveness. Furthermore, permissiveness was down-regulated upon transfection of CD81 silencing RNA into a CD81-positive cell clone. In conclusion, CD81 expression is an important determinant of HCV permissiveness of Huh7 cell clones harboring different characteristics.
Independent Evolution of Human Immunodeficiency Virus Type 1
env
V1/V2 and V4/V5 Hypervariable Regions during Chronic Infection
Authors: Harrington Patrick R. , Nelson Julie A. E. , Kitrinos Kathryn M. , Swanstrom Ronald
Published: March 2007

Using DNA heteroduplex tracking assays, we characterized human immunodeficiency virus type 1
env
V4/V5 genetic populations in multiple blood plasma samples collected over an average of 7 months from 24 chronically infected human subjects. We observed complex and dynamic V4/V5 genetic populations in most subjects. Comparisons of V4/V5 and V1/V2 population changes over the course of the study showed that major shifts in genetic populations frequently occurred in one region but not the other, and these observations were independently confirmed in one subject by single-genome sequencing. These results suggest that the V1/V2 and V4/V5 regions of
env
often evolve independently during chronic infection.
Direct Evidence of Lower Viral Replication Rates In Vivo in Human Immunodeficiency Virus Type 2 (HIV-2) Infection than in HIV-1 Infection
Authors: MacNeil Adam , Sarr Abdoulaye Dieng , Sankalé Jean-Louis , Meloni Seema Thakore , Mboup Souleymane , Kanki Phyllis
Published: March 2007

Studies have shown that human immunodeficiency virus type 2 (HIV-2) is less pathogenic than HIV-1, with a lower rate of disease progression. Similarly, plasma viral loads are lower in HIV-2 infection, suggesting that HIV-2 replication is restricted in vivo in comparison to that of HIV-1. However, to date, in vivo studies characterizing replication intermediates in the viral life cycle of HIV-2 have been limited. In order to test the hypothesis that HIV-2 has a lower replication rate in vivo than HIV-1 does, we quantified total viral DNA, integrated proviral DNA, cell-associated viral mRNA, and plasma viral loads in peripheral blood samples from groups of therapy-naïve HIV-1-infected (
n
= 21) and HIV-2-infected (
n
= 18) individuals from Dakar, Senegal, with CD4
+
T-cell counts of >200/μl. Consistent with our previous findings, total viral DNA loads were similar between HIV-1 and HIV-2 and plasma viral loads were higher among HIV-1-infected individuals. Proportions of DNA in the integrated form were also similar between these viruses. In contrast, levels of viral mRNA were lower in HIV-2 infection. Our study indicates that HIV-2 is able to establish a stable, integrated proviral infection in vivo, but that accumulation of viral mRNA is attenuated in HIV-2 infection relative to that in HIV-1 infection. The differences in viral mRNA are consistent with the differences in plasma viral loads between HIV-1 and HIV-2 and suggest that lower plasma viral loads, and possibly the attenuated pathogenesis of HIV-2, can be explained by lower rates of viral replication in vivo.
A Shared Transcription Termination Signal on Negative and Ambisense RNA Genome Segments of Rift Valley Fever, Sandfly Fever Sicilian, and Toscana Viruses
Authors: Albariño César G. , Bird Brian H. , Nichol Stuart T.
Published: March 2007

The
Phlebovirus
genus (family
Bunyaviridae
) is composed of a diverse group of arboviruses that cause disease syndromes ranging from mild febrile illness to hemorrhagic fever with high fatality. Although antigenically similar, these viruses differ by approximately 25% at the genome level, and their ecologies, including geographic ranges, preferred vector species, and hosts, vary considerably. In contrast to other ambisense viruses, where RNA hairpin structures which serve as transcription termination signals are frequently found separating the opposite-sense open reading frames, no evidence of predicted high-energy hairpin structures was found at the ambisense junctions of phlebovirus S RNA segments. However, a conserved sequence motif was identified on both negative and ambisense genome segments that functions as a transcription termination signal for the N, NSs, and GPC mRNAs in three diverse phleboviruses, namely, Rift Valley fever, sandfly Sicilian, and Toscana viruses. The exact termination of nascent virus mRNA molecules was determined by 3′ rapid amplification of cDNA ends. Surprisingly, analysis of the termini of mRNAs from both S and M segments of these three viruses revealed that transcription termination occurred immediately upstream of a conserved sequence motif with the general features 3′-C
1-3
GUCG/A-5′. In contrast, no corresponding sequence motif was found in the L segments, and analysis indicated a “runoff” transcript approach to L mRNA termination. The absolute requirement of the identified transcription termination motif was demonstrated by using a highly efficient Rift Valley fever virus reverse genetics system to generate live recombinant viruses with S segments lacking the termination signal motif for the NP or NSs mRNA and showing that these recombinant viruses generated mRNAs that failed to terminate correctly.
Immunoadhesins Containing Pre-S Domains of Hepatitis B Virus Large Envelope Protein Are Secreted and Inhibit Virus Infection
Authors: Chai Ning , Gudima Severin , Chang Jinhong , Taylor John
Published: March 2007

Hepatitis B virus (HBV) replication produces three envelope proteins (L, M, and S) that have a common C terminus. L, the largest, contains a domain, pre-S1, not present on M. Similarly M contains a domain, pre-S2, not present on S. The pre-S1 region has important functions in the HBV life cycle. Thus, as an approach to studying these roles, the pre-S1 and/or pre-S2 sequences of HBV (serotype
adw
2, genotype A) were expressed as N-terminal fusions to the Fc domain of a rabbit immunoglobulin G chain. Such proteins, known as immunoadhesins (IA), were highly expressed following transfection of cultured cells and, when the pre-S1 region was present, >80% were secreted. The IA were myristoylated at a glycine penultimate to the N terminus, although mutation studies showed that this modification was not needed for secretion. As few as 30 amino acids from the N terminus of pre-S1 were both necessary and sufficient to drive secretion of IA. Even expression of pre-S1 plus pre-S2, in the absence of an immunoglobulin chain, led to efficient secretion. Overall, these studies demonstrate an unexpected ability of the N terminus of pre-S1 to promote protein secretion. In addition, some of these secreted IA, at nanomolar concentrations, inhibited infection of primary human hepatocytes either by hepatitis delta virus (HDV), a subviral agent that uses HBV envelope proteins, or HBV. These IA have potential to be part of antiviral therapies against chronic HDV and HBV, and may help understand the attachment and entry mechanisms used by these important human pathogens.
Short-term effects of a non-dieting lifestyle intervention program on weight management, fitness, metabolic risk, and psychological well-being in obese premenopausal females with the metabolic syndrome
Authors: Carroll Sean , Borkoles Erika , Polman Remco
Published: March 2007

Lifestyle modification has been widely acknowledged as the primary treatment for the metabolic syndrome (MetS). We examined the short-term effects of a non-dieting lifestyle intervention program, within the theoretical psychological framework of self-determination theory (SDT), on metabolic fitness and psychological well-being among premenopausal, clinically obese women. A secondary analysis of a randomized, controlled, 3 month, intensive, community-based lifestyle intervention study was performed on 31 pre-menopausal obese women with the MetS (56.4% of original study sample). These participants had been randomly allocated to a non-dieting lifestyle intervention group (n = 17) or waiting list control (n = 14). Among participants who completed repeat anthropometric and cardiorespiratory fitness measurements after 3 months intervention, the lifestyle intervention group showed a significant improvement in VO2 (mL·kg–1·min–1) compared with control (test for interaction, p = 0.003). No significant difference was found for body mass. Metabolic improvements were evident for diastolic blood pressure and high-density lipoprotein cholesterol in both groups. The lifestyle intervention group also showed significantly improved general psychological well-being compared with the control group (test for interaction, p = 0.0005). All of the psychological well-being subscales showed significant favourable changes in the intervention group as compared with controls. This short-term, non-dieting lifestyle intervention, consistent with the “Health at Every Size” (HAES) obesity treatment paradigm, significantly improved cardiorespiratory fitness and psychological well-being. Metabolic risk tended to improve after 3 months intervention with no significant difference in the resolution of the MetS between intervention and control participants.
SYSTEMATIC STUDY OF THESU(3)c⊗SU(4)L⊗U(1)XGAUGE SYMMETRY
Authors: PONCE WILLIAM A. , A. SÁNCHEZ LUIS
Published: February 2007

We carry out a systematic study of possible extensions of the standard model based on the gauge group SU (3)c⊗ SU (4)L⊗ U (1)X. We consider models with particles having exotic electric charges and also models which do not contain exotic electric charges in the gauge boson sector or in the fermion sector. For the first case an infinite number of models can, in principle, be constructed, while the restriction to non-exotic electric charges only allows for eight different anomaly-free models. Four of them are three-family models in the sense that anomalies cancel by an interplay between the three families, and another two are one-family models where anomalies cancel family by family as in the standard model. The remaining two are two-family models.
THE MSSM ON THE INTERVAL
Authors: VON GERSDORFF GERO
Published: February 2007

We review electroweak symmetry breaking in supersymmetric models with a compact fifth dimension, the interval. We show how boundary conditions for hypermultiplets can be obtained dynamically by brane mass terms, and present formulas for the spectrum in the presence of general bulk mass matrices. After giving a brief overview on the literature of models, we describe in detail a recently proposed model that at energies below the compactification scale reduces to the MSSM with a very peculiar superpartner spectrum.
DETERMINISTIC AND EVOLUTIONARY EXTRACTION OF DELTA-LOGNORMAL PARAMETERS: PERFORMANCE COMPARISON
Authors: DJIOUA MOUSSA , PLAMONDON RÉJEAN , DELLA CIOPPA ANTONIO , MARCELLI ANGELO
Published: February 2007

A theory, called the Kinematic Theory of Rapid Human Movement, was proposed a few years ago to analyze rapid human movements, called the Kinematic Theory of Rapid Human Movements, based on a delta-lognormal equation that globally describes the basic properties of the velocity profiles of an end-effector using seven parameters. This realistic model has been very useful for proposing original solutions to various pattern recognition problems (signature segmentation and verification, handwriting analysis and synthesis, etc.). Most of these applications rely on the use of an efficient algorithm to extract the delta-lognormal parameters from real data with the best possible fit. In this paper, we compare two such algorithms: a deterministic one, based on nonlinear regression, and a Breeder Genetic algorithm. The performance of these two algorithms and of their combinations are compared using the same artificial database, composed of analytical delta-lognormal profiles and their noisy versions (20 dB SNR). In the free-noise case, the analysis of the experimental results shows that the deterministic approach leads to better results than the evolutionary one, while under the extremely noisy conditions selected, the evolutionary approach seems to be less sensitive to noise, but is nevertheless less successful than the deterministic search.
INCORPORATING A WAVELET TRANSFORM INTO A SALIENCY-BASED METHOD FOR ONLINE HANDWRITING SEGMENTATION
Authors: DE STEFANO CLAUDIO , D'ELIA CIRO , DI FRECA ALESSANDRA SCOTTO , MARCELLI ANGELO
Published: February 2007

In the framework of a saliency-based approach for segmenting cursive handwriting into elementary strokes, we propose a smoothing technique based on the use of a Wavelet Transform to describe the electronic ink at different resolutions. According to such an approach, derived in analogy with those proposed in the literature for early visual tasks in primates, curvature maxima corresponding to actual segmentation points are separated from those produced by the different source of noise affecting the handwriting generation process. This is obtained by evaluating the curvature maxima at different levels of resolution, and by arranging them into a pyramidal structure, from which a saliency map is eventually achieved by combining the values across all possible scales. Such maps enjoy the property of exhibiting higher values in correspondence of regions of the original ink where curvature maxima survive along difference scales, thus indicating that those regions should correspond to the parts of the ink where two strokes join. Experiments performed by using both standard databases and one of online words collected in our laboratory, have shown high performance in terms of correct segmentation, stability and predictability of the results.
EXACTLY SOLVABLE PAIRING HAMILTONIANS
Authors: DUKELSKY J. , ERREA B. , LERMA H. S. , PITTEL S.
Published: February 2007

We review the development of the microscopic BCS theory of superconductivity and the exact solution of the pairing Hamiltonian given by Richardson in 1963. We then introduce the generalized Richardson-Gaudin exactly-solvable pairing models for SU(2) (pairing between like particles), SO(5) ( T =1 pairing) and SO(8) ( T =0,1 pairing) algebras.
PAIRING CORRELATIONS BEYOND THE MEAN FIELD
Authors: BENDER M. , DUGUET T.
Published: February 2007

We discuss dynamical pairing correlations in the context of configuration mixing of projected self-consistent mean-field states, and the origin of a divergence that might appear when such calculations are done using an energy functional in the spirit of a naive generalized density functional theory.
PAIRING AS A COLLECTIVE MODE
Authors: POMORSKI KRZYSZTOF
Published: February 2007

The collective pairing hamiltonian is obtained in the framework of the generator coordinate method using the Gaussian overlap approximation. A slightly modified BCS wave function is used as a generator function. The pairing gap parameter Δ and the gauge transformation angle ϕ are chosen as generator coordinates. This model gives not only an approximate particle-number projection but also the form of the ground state collective wave function in the (Δ, ϕ) plane. It was found that the most probable Δ does not corresponds to the minimum (Δ eq ) of the energy function E BCS (Δ) but it is systematically shifted towards smaller values than Δ eq . This effect is due to the strong dependence of the mass parameters on the pairing gap. The influence of the dynamics in the pairing degrees of freedom on the fission life-times as well as the quadrupole collective excitations is examined.
QUASILOCAL DENSITY FUNCTIONAL THEORY FOR NUCLEI INCLUDING PAIRING CORRELATIONS
Authors: VIÑAS X. , TSELYAEV V. I. , SOUBBOTIN V. B. , KREWALD S.
Published: February 2007

We propose first a generalization of the Density Functional Theory leading to single-particle equations of motion with a quasilocal mean-field operator containing a position-dependent effective mass and a spin-orbit potential. Ground-state properties of doubly magic nuclei are obtained within this framework using the Gogny D1S force and compared with the exact Hartree-Fock values. Next, extend the Density Functional Theory to include pairing correlations without formal violation of the particle-number condition. This theory, which is nonlocal, is simplified by a suitable quasilocal reduction. Some calculations to show the ability of this theory are presented.
RENORMALIZATION GROUP APPROACH TO THE PAIRING INSTABILITIES
Authors: DOMAŃSKI T. , DONABIDOWICZ A.
Published: February 2007

By means of the continuous unitary transformation similar to a general scheme of the Renormalization Group (RG) procedure we study the issue of symmetry breaking and pairing instability in the system of interacting fermions. Constructing a generalized version of the Bogoliubov transformation we show that formation of the fermion pairs and their superconductivity/superfluidity can appear at different temperatures. It is shown that strong quantum fluctuations can destroy the long-range order without breaking the fermion pairs which may still exist as incoherent and/or damped entities. Such unusual phase is characterized by a partial suppression of the density of states near the Fermi energy and by residual collective features like the sound-wave mode in the fermion pair spectrum.
HIGH-SPIN STRUCTURES AS THE PROBES OF PROTON-NEUTRON PAIRING
Authors: AFANASJEV A. V.
Published: February 2007

Rotating N = Z nuclei in the mass A = 58-80 region have been studied within the framework of isovector mean field theory. Available data is well and systematically described in the calculations. The present study supports the presence of strong isovector np pair field at low spin, which is, however, destroyed at high spin. No clear evidence for the existence of the isoscalar t = 0 np pairing has been found.
PARTICLE NUMBER CONSERVING APPROACH TO CORRELATIONS
Authors: SIEJA K. , HA T. L. , QUENTIN P. , BARAN A.
Published: February 2007

In the present work the so-called Higher Tamm-Dancoff Approximation method is presented for the generalized case of isovector and isoscalar residual interactions treated simultaneously. The role of different particle-hole excitations and of proton-neutron pairing correlations in the ground state of the self-conjugate 64 Ge nucleus is discussed.
PAIRING AND α-DECAY
Authors: BARAN A. , ŁOJEWSKI Z. , SIEJA K.
Published: February 2007

Nuclear pairing interaction plays a crucial role in both macroscopic-microscopic and fully macroscopic descriptions of nuclei. In the present study we discuss different pairing interactions (monopole and δ pairing forces) and the methods allowing for the particle number symmetry restoration in addition to the customary BCS treatment of pairing correlations in the context of α-decay half-lives for superheavy nuclei. The calculations are done in the macroscopic-microscopic framework for even-even nuclei with Z > 110.
COLLECTIVE PAIRING HAMILTONIAN IN A SELF-CONSISTENT APPROACH
Authors: PRÓCHNIAK L.
Published: February 2007

We present general results for mass parameters and a collective potential energy obtained by ATDHFB and GCM+GOA methods for a state dependent pairing interaction. We apply the ATDHFB method in the case of mean-field calculations with Skyrme interaction for the 128 Xe nucleus. Dependence of the collective Hamiltonian and its ground state on the strength of the δ pairing interaction is discussed.
CLUSTER MODEL VERSUS FERMI-FLUID APPROACH TO FISSION THEORY
Authors: KRAPPE H. J.
Published: February 2007

Landau's approach to the theory of nearly degenerate Fermi liquids allows to reduce an A fermion problem to that of just a few particle-hole excitations, thus making the treatment of many of these systems only possible. In contrast, the cluster model suggests to separate the A particles into two groups and study their relative motion, which incorporates a later corresponding binary split of the system in the very ansatz for the wave function. However, the proper antisymmetrization of the wave function makes it in practice impossible to apply this concept to any larger system. We show how the use of the nuclear correlation diagram allows to combine the idea of preformed clusters with the technical advantages of the Fermi fluid concept.
COLLECTIVE INERTIA AND FISSION BARRIERS WITHIN THE SKYRME-HARTREE-FOCK THEORY
Authors: BARAN A. , STASZCZAK A. , DOBACZEWSKI J. , NAZAREWICZ W.
Published: February 2007

Spontaneous fission barriers, quadrupole inertia tensor, and zero-point quadrupole correlation energy are calculated for 252,256,258 Fm in the framework of the self-consistent Skyrme-Hartree-Fock+BCS theory. Two ways of computing collective inertia are employed: the Gaussian Overlap Approximation to the Generator Coordinate Method and cranking ansatz. The Skyrme results are compared with those of the Gogny-Hartree-Fock-Bogolyubov model.
NUCLEI WITH TETRAHEDRAL SYMMETRY
Authors: DUDEK J. , DOBACZEWSKI J. , DUBRAY N. , GÓŹDŹ A. , PANGON V. , SCHUNCK N.
Published: February 2007

We discuss a point-group-theory based method of searching for new regions of nuclear stability. We illustrate the related strategy with realistic calculations employing the tetrahedral and the octahedral point groups. In particular, several nuclei in the Rare Earth region appear as excellent candidates to study the new mechanism.
NUCLEAR LEVEL DENSITY PARAMETER WITH YUKAWA FOLDED POTENTIAL
Authors: POMORSKI KRZYSZTOF , NERLO-POMORSKA BOŻENA , BARTEL JOHANN
Published: February 2007

The average dependence of the single-particle level-density parameter on mass number A, isospin and deformation is determined using the Yukawa folded mean-field potential for spherical and deformed nuclei at temperatures 0 ≤ T ≤ 5 MeV and elongations ranging from oblate shapes to the scission configuration of fissioning nuclei. The results are compared with similar estimates obtained previously using the relativistic mean-field theory, the Skyrme Hartree-Fock and the Thomas-Fermi approach.
BOSON APPROACH TO THE STRUCTURE OF A = 62 NUCLEI
Authors: KWASNIEWICZ EDWARD , HETMANIOK EDYTA
Published: February 2007

The procedure to transfer the description of a fermion system from the truncated shell model space built in terms of collective pairs onto a space of corresponding bosons has been discussed. The procedure has been applied to systems of six nucleons in the 1p0f shell under the assumption that valence nucleons occupy the 1p3/2, 1p1/2and 0f5/2orbitals while the 0f7/2subshell is closed. The boson Hamiltonian has been deduced from the shell-model one. The effects of the truncation of the boson Hamiltonian to one- and two-body terms have been examined.
A BILATTICE-BASED FRAMEWORK FOR HANDLING GRADED TRUTH AND IMPRECISION
Authors: DESCHRIJVER GLAD , ARIELI OFER , CORNELIS CHRIS , KERRE ETIENNE E.
Published: February 2007

We present a family of algebraic structures, called rectangular bilattices, which serve as a natural accommodation and powerful generalization to both intuitionistic fuzzy sets (IFSs) and interval-valued fuzzy sets (IVFSs). These structures are useful on one hand to clarify the exact nature of the relationship between the above two common extensions of fuzzy sets, and on the other hand provide an intuitively attractive framework for the representation of uncertain and potentially conflicting information. We also provide these structures with adequately defined graded versions of the basic logical connectives, and study their properties and relationships. Application potential and intuitive appeal of the proposed framework are illustrated in the context of preference modeling.
SOME GENERAL PROPERTIES OF A FUZZY SINGLE MACHINE SCHEDULING PROBLEM
Authors: KASPERSKI ADAM
Published: February 2007

In this paper a general formulation of a fuzzy single machine scheduling problem is proposed. Such notions as schedule, precedence relation and cost function in the fuzzy case are defined. The concept of f-regular function, being a generalization of a regular function, known from the classical theory of scheduling is introduced. A wide class of problems with f-regular cost functions is analyzed and some general properties of such problems are shown.
MODELLING DEPENDENCE IN DEMPSTER-SHAFER THEORY
Authors: MONNEY PAUL-ANDRE , CHAN MOSES
Published: February 2007

Belief functions can only be combined by Dempster's rule when they are based on independent items of evidence. This paper proposes a method for handling the case where there is some probabilistic dependence among the items of evidence. The method relies on compact representations of joint probability distributions on the assumption variables associated with the belief functions. These distributions are then used to compute degrees of support of hypotheses of interest. It is shown that the theory of hints is the appropriate general framework for this method.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: Kreinovich Vladik
Published: February 2007

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@utep.edu, or by regular mail to: V. Kreinovich, Department of Computer Science, University of Texas, El Paso, TX 79968, USA.
COMPONENTWISE SPLITTING METHODS FOR PRICING AMERICAN OPTIONS UNDER STOCHASTIC VOLATILITY
Authors: IKONEN SAMULI , TOIVANEN JARI
Published: March 2007

Efficient numerical methods for pricing American options using Heston's stochastic volatility model are proposed. Based on this model the price of a European option can be obtained by solving a two-dimensional parabolic partial differential equation. For an American option the early exercise possibility leads to a lower bound for the price of the option. This price can be computed by solving a linear complementarity problem. The idea of operator splitting methods is to divide each time step into fractional time steps with simpler operators. This paper proposes componentwise splitting methods for solving the linear complementarity problem. The basic componentwise splitting decomposes the discretized problem into three linear complementarity problems with tridiagonal matrices. These problems can be efficiently solved using the Brennan and Schwartz algorithm, which was originally introduced for American options under the Black and Scholes model. The accuracy of the componentwise splitting method is increased by applying the Strang symmetrization. The good accuracy and the computational efficiency of the proposed symmetrized splitting method are demonstrated by numerical experiments.
High-Sensitivity and High-Resolution Contact Hole Patterning by Enhanced-Wettability Developer
Authors: Shimada Hisayuki , Shimomura Shigeki , Hirose Kouichi , Ohmi Tadahiro
Published: February 2007

We have determined that high-sensitivity and high-resolution contact hole photoresist patterning can be achieved using an optimized combination of developer, added surfactant and ammonium chloride salt. The addition of surfactant improves the wettability of the developer to promote resist dissolution. The presence of ammonium chloride salt protects the sidewall of the contact hole resist pattern to achieve good pattern profile. The optimal developer can form contact hole patterns smaller than the illumination wavelength of the stepper without the use of phase shifting technology.
Fine Particle Inspection Down to 38 nm on Bare Wafer with Micro Roughness by Side-Scattering Light Detection
Authors: Minori Noguchi Minori Noguchi , Yukio Kembo Yukio Kembo
Published: February 2007

A system for detecting fine particles on LSI wafers is proposed. This system illuminates the wafer with a laser at a large angle of incidence, and uses a detector with a small pixel size. In this way, optical noise from the bare wafer is reduced, enabling the detection of standard 38-nm particles. Optical noise from a wafer surface is analyzed and shown to be caused by diffracted light. Simulation with a diffraction model indicates that the optical noise level is related to the wafer roughness. To detect fine particles with a high probability of 95%, a high illumination energy of 180 J is needed. With small pixels, a low illumination energy of 1.2 J will also detect small 50-nm particles, but with a low probability of 10%. This technique will be useful in monitoring the cleanliness of submicron LSI production.
Study of Submicron SrTiO3 Patterning
Authors: Aoki Hidemitsu , Hashimoto Toshiki , Ikawa Eiji , Kikkawa Takamaro , Takeuchi Kiyoshi , Yamamichi Shintaro , Sakuma Toshiyuki , Miyasaka Yoichi
Published: February 2007

Features of thin strontium titanate (SrTiO3) films are a high dielectric constant (εr) and chemical and structural stability. Submicron SrTiO3 patterning is necessary for realizing future planar dynamic random access memory (DRAM) structures to suppress parasitic capacitance. The etching technology and reaction with SrTiO3 film were investigated. It was found that the SrTiO3 film could be chemically etched by Cl2 and SF6 mixture gas, and 0.6 µm SrTiO3 patterns were etched by Cl2 with 10%-SF6 gases. In addition, the side wall deposition layer was removed by rinsing with CH3COOH, HNO3 and HF mixture solution.
The Lateral Electric Field Model for Substrate and Gate Current of Stressed SC-PMOSFET
Authors: Yang Kwang Sun , Park Jong Tae , Bong Ryul Kim Bong Ryul Kim
Published: February 2007

In this paper, we present the change of the lateral electric field distribution with the trapped electron charge and the analytical models for I
sub and I
g of stressed SC-PMOSFET in the saturation region. To derive the hot-electron-induced electric field in the damage region, Ko's box model is modified. Our modified field model can explain the reduction of the lateral electric field with the trapped electron charge and the decrease of I
sub and I
g of stressed SC-PMOSFET. The decreasing phenomenon of I
sub(max.) and I
g(max.) in relation to the calculated N
t and E
m during the stress time shows that there are decrease in I
sub(max.) and I
g(max.) with the increase in N
t and with the decrease in E
m. Calculated I
sub and I
g of stressed SC-PMOSFET using our modified lateral electric field agreed with experimental data.
Silicon Nitride Film for High-Mobility Thin-Film Transistor by Hybrid-Excitation Chemical Vapor Deposition
Authors: Shigeichi Yamamoto Shigeichi Yamamoto , Masatoshi Migitaka Masatoshi Migitaka
Published: February 2007

A hybrid-excitation technique was applied to nitrify amorphous silicon (a-Si:H) film surface using ammonia (NH3) gas and to deposit silicon nitride (SiN
x
) film using disilane (Si2H6) and NH3 gases for an a-Si:H thin-film transistor (TFT) at 280°C. With the use of this SiN
x
film as a gate insulator, a coplanar a-Si:H TFT with high field-effect electron mobility (5.3 cm2/(V·s)) was fabricated. This high electron mobility is considered to be due to three features as follows: (1) a good SiN
x
/a-Si:H interface created by the hybrid-excited nitrification of the a-Si:H film surface, (2) an ion-bombardment-free nitrogen-rich SiN
x
film fabricated by hybrid-excitation chemical vapor deposition (CVD) and (3) an a-Si:H film with less ion-bombardment damage. This hybrid-excited nitrification and the CVD effects on electrical properties of SiN
x
/(100)Si interface are also discussed.
Effects of Growth Parameters on Oxygen Incorporation into InGaAlP Grown by Metalorganic Chemical Vapor Deposition
Authors: Nishikawa Yukie , Mariko Suzuki Mariko Suzuki , Masaki Okajima Masaki Okajima
Published: February 2007

Oxygen incorporation into In0.5(Ga1-x
Al
x
)0.5P grown by metalorganic chemical vapor deposition has been quantitatively investigated as a function of growth parameters. The oxygen concentration (N
O) increased with increasing Al composition (x). Marked decreases in N
O for x=0.7 and 1.0 were observed as the V/III ratio (molar flow rate ratio of group-V to group-III sources) was increased, although N
O for x=0.7 was almost independent of the substrate temperature (T
S). Since N
O for x=1.0 was strongly affected by the amount of oxygen-containing species in trimethylaluminum (TMA), the origin of oxygen in InGaAlP is thought to be TMA. Net acceptor concentration (N
A-N
D) in Zn-doped InGaAlP for x=0.7 and 1.0 decreased with increasing N
O. Oxygen may act as a deep donor, compensating for Zn acceptors.
Single Electron Tunneling Observed in a 2D Tunnel Junction Array at Room Temperature
Authors: Nejoh Hitoshi , Aono Masakazu
Published: February 2007

A 2D tunnel junction array has been constructed using liquid crystal (LC) molecules. The LC molecules are aligned between PtPd islands on a substrate and these LC molecules-PtPd islands make tunnel junctions. The behavior of this junction array can be described in terms of single electron solitons. By voltage sourcing this 2D array, it shows the DC i-v curve characteristic of single-electron tunneling. Since the capacitance is so small (∼10-19 F), the Coulomb blockade can be observed even at room temperature, with a value of approximately 100 mV.
Photoreflectance Study of GaAs/GaAsP Strained-Barrier Quantum Well Structures
Authors: Yaguchi Hiroyuki , Zhang Xiong , Ota Kazunobu , Nagahara Masaki , Onabe Kentaro , Shiraki Yasuhiro , Ryoichi Ito Ryoichi Ito
Published: February 2007

GaAs/GaAs1-x
P
x
strained-barrier quantum well structures grown by metalorganic vapor phase epitaxy (MOVPE) have been investigated using photoreflectance (PR) spectroscopy. On the basis of the square-potential model, we have determined the band offsets at the heterojunction and their dependence on the phosphorus composition. It was found that in the GaAs/GaAs1-x
P
x
strained-barrier quantum well, the band offsets are almost linearly dependent on the phosphorus composition in the range of x≤0.23. In addition, it was derived that the conduction band offset ratio Q
c=0.57±0.05. This result is consistent with our previous study concerning GaAs/GaAsP “strained-well” quantum well structures.
Behavior of Misfit Dislocations in GaAs Epilayers Grown on Si at Low Temperature by Molecular Beam Epitaxy
Authors: Asai Koyu , Hisashi Katahama Hisashi Katahama , Yasunari Shiba Yasunari Shiba
Published: February 2007

The behavior of misfit dislocations in GaAs buffer layers grown on Si was investigated by the measurement of stresses using optical interferometry and X-ray diffraction. The buffer layers grown at 250°C with various thicknesses (0.05∼0.20 µm) were annealed at various temperatures (400∼600°C). The overlayers were grown at 300°C. With increasing annealing temperature or thickness, the stresses changed from compressive to tensile. The stress-free GaAs/Si wafer was produced with a 0.10-µm-thick buffer layer annealed at 500°C. These results indicate that in low-temperature growth, it is important to optimize both the annealing temperature and the thickness of the buffer layer. In addition, the asymmetric stresses were observed between [011] and [01̄1]. This asymmetry was caused by the difference in dislocation velocities or nucleation energies between α- and β-dislocations.
Charge-Balanced Heteroepitaxial Growth of GaAs on Si
Authors: Maehashi Kenzo , Shigehiko Hasegawa Shigehiko Hasegawa , Hisao Nakashima Hisao Nakashima
Published: February 2007

We propose charge-balanced heteroepitaxy, where the GaAs/Si interface is neutralized by inserting one monolayer of column II elements in place of the Ga atoms at the GaAs/Si interface. We have constructed this structure using Be atoms, and have investigated the initial stages of GaAs molecular beam epitaxial growth on this charge-balanced surface by high-energy electron diffraction, and ultraviolet and X-ray photoemission spectroscopy. These measurements reveal that the charge-balanced structure neutralizes the GaAs/Si interface, and the GaAs growth mode proceeds in a Stranski-Krastanow mode.
Plasma-Assisted Epitaxial Growth of P-Type ZnSe in Nitrogen-Based Plasma
Authors: Hamada Tomoji , Ono Takashi Hariu
Published: February 2007

P-type ZnSe films have been successfully grown by plasma-assisted epitaxy in nitrogen-based plasma, and the resistivity of the film was reduced to the order of 10 Ω·cm at room temperature. With a relatively low nitrogen gas flow rate of around 0.073 sccm, low-temperature photoluminescence intensities of donor-acceptor pair emission and acceptor-bound exciton emission from N-doped ZnSe were maximum with negligible deep-level emission at the partial pressure ratio P
N2/(P
H2+P
N2) of around 80%. Atomic nitrogen generated by the Penning effect around this partial pressure ratio was observed. It has been suggested that, while hydrogen improves the electronic property of ZnSe layers, excessive hydrogen can reduce the doping efficiency of shallow-acceptor nitrogen.
Photopumped Blue Lasers with ZnSSe-ZnMgSSe Double Heterostructure and Attempt at Doping in ZnMgSSe
Authors: Morinaga Yuko , Hiroyuki Okuyama Hiroyuki Okuyama , Katsuhiro Akimoto Katsuhiro Akimoto
Published: February 2007

We observed the lasing operation of ZnSSe-ZnMgSSe double heterostructure (DH) photopumped blue lasers up to 500 K. The wavelength at room temperature (RT) and threshold intensity at 300 K were 464.5 nm and 105 kW/cm2, respectively. Characteristic temperature (T
0) was estimated to be 170 K. These results indicate that this structure has good thermal stability. Both n-type and p-type doping in ZnMgSSe were successfully performed. Both n-type and p-type ZnMgSSe show good properties for fabricating laser diodes.
Teaching simple experimental design to undergraduates: do your students understand the basics?
Authors: Hiebert Sara M.
Published: February 2007

This article provides instructors with guidelines for teaching simple experimental design for the comparison of two treatment groups. Two designs with specific examples are discussed along with common misconceptions that undergraduate students typically bring to the experiment design process. Features of experiment design that maximize power and minimize the effects of interindividual variation, thus allowing reduction of sample sizes, are described. Classroom implementation that emphasizes student-centered learning is suggested, and thought questions, designed to help students discover and name the basic principles of simple experiment design for themselves, are included with an answer key.
What makes physiology hard for students to learn? Results of a faculty survey
Authors: Michael Joel
Published: February 2007

Teachers of physiology at all postsecondary levels were asked to participate in a survey about the possible sources of students’ difficulty in learning physiology. Sixty-three physiology teachers responded to the 18-question survey; 35 of the respondents also responded to a request for written comments about this issue prior to taking the survey. Three categories of possible factors contributing to physiology being hard to learn were defined: 1) the nature of the discipline, 2) the way it is taught, and 3) what students bring to the task of learning physiology. Respondents thought that characteristics of the discipline (it requires causal reasoning, it uses graphs and mathematics, and it is highly integrative) and characteristics of students (they believe that learning and memorizing are the same thing, they cannot or will do attempt to integrate, and they compartmentalize) were significantly more important than any aspect of teaching in making physiology hard to learn. Recommendations are offered in this article to help students deal with the sources of difficulty that were identified.
Modeling transmural heterogeneity of KATP current in rabbit ventricular myocytes
Authors: Michailova Anushka , Lorentz William , McCulloch Andrew
Published: March 2007

To investigate the mechanisms regulating excitation-metabolic coupling in rabbit epicardial, midmyocardial, and endocardial ventricular myocytes we extended the LabHEART model (Puglisi JL and Bers DM. Am J Physiol Cell Physiol 281: C2049–C2060, 2001). We incorporated equations for Ca2+ and Mg2+ buffering by ATP and ADP, equations for nucleotide regulation of ATP-sensitive K+ channel and L-type Ca2+ channel, Na+-K+-ATPase, and sarcolemmal and sarcoplasmic Ca2+-ATPases, and equations describing the basic pathways (creatine and adenylate kinase reactions) known to communicate the flux changes generated by intracellular ATPases. Under normal conditions and during 20 min of ischemia, the three regions were characterized by different INa, Ito, IKr, IKs, and IKp channel properties. The results indicate that the ATP-sensitive K+ channel is activated by the smallest reduction in ATP in epicardial cells and largest in endocardial cells when cytosolic ADP, AMP, PCr, Cr, Pi, total Mg2+, Na+, K+, Ca2+, and pH diastolic levels are normal. The model predicts that only KATP ionophore (Kir6.2 subunit) and not the regulatory subunit (SUR2A) might differ from endocardium to epicardium. The analysis suggests that during ischemia, the inhomogeneous accumulation of the metabolites in the tissue sublayers may alter in a very irregular manner the KATP channel opening through metabolic interactions with the endogenous PI cascade (PIP2, PIP) that in turn may cause differential action potential shortening among the ventricular myocyte subtypes. The model predictions are in qualitative agreement with experimental data measured under normal and ischemic conditions in rabbit ventricular myocytes.
Nitric oxide regulation of mitochondrial oxygen consumption II: molecular mechanism and tissue physiology
Authors: Cooper Chris E. , Giulivi Cecilia
Published: March 2007

Nitric oxide (NO) is an intercellular signaling molecule; among its many and varied roles are the control of blood flow and blood pressure via activation of the heme enzyme, soluble guanylate cyclase. A growing body of evidence suggests that an additional target for NO is the mitochondrial oxygen-consuming heme/copper enzyme, cytochrome c oxidase. This review describes the molecular mechanism of this interaction and the consequences for its likely physiological role. The oxygen reactive site in cytochrome oxidase contains both heme iron ( a3) and copper (CuB) centers. NO inhibits cytochrome oxidase in both an oxygen-competitive (at heme a3) and oxygen-independent (at CuB) manner. Before inhibition of oxygen consumption, changes can be observed in enzyme and substrate (cytochrome c) redox state. Physiological consequences can be mediated either by direct “metabolic” effects on oxygen consumption or via indirect “signaling” effects via mitochondrial redox state changes and free radical production. The detailed kinetics suggest, but do not prove, that cytochrome oxidase can be a target for NO even under circumstances when guanylate cyclase, its primary high affinity target, is not fully activated. In vivo organ and whole body measures of NO synthase inhibition suggest a possible role for NO inhibition of cytochrome oxidase. However, a detailed mapping of NO and oxygen levels, combined with direct measures of cytochrome oxidase/NO binding, in physiology is still awaited.
Distinct Vascular Conduction With Cortical Spreading Depression
Authors: Brennan Kevin C. , Beltrán-Parrazal Luis , López-Valdés Hector E. , Theriot Jeremy , Toga Arthur W. , Charles Andrew C.
Published: March 2007

Cortical spreading depression (CSD) is associated with significant vasodilatation and vasoconstriction, but the relationship between the cortical parenchymal and vascular phenomena remains poorly understood. We used optical intrinsic signal (OIS) imaging and electrophysiology to simultaneously examine the vascular and parenchymal changes that occur with CSD in anesthetized mice and rats. CSD was associated with a propagated multiphasic change in optical reflectance, with correlated negative DC shift in field potential. Dilatation of cortical surface arterioles propagated with a significantly greater intrinsic velocity than the parenchymal CSD wavefront measured by OIS and electrophysiology. Dilatation traveled in a circuitous pattern along individual arterioles, indicating specific vascular conduction as opposed to concentric propagation of a parenchymal signal. Arteriolar dilatation propagated into areas beyond the spread of parenchymal OIS and electrophysiological changes of CSD. Conversely, vasomotor activity could be experimentally dissociated from the parenchymal CSD wave. Frequent repetitive CSD evoked by continuous stimulation was associated with a reduced or absent arteriolar response despite preserved parenchymal OIS and electrophysiological changes. Similarly, dimethylsulfoxide at high concentrations (10%) inhibited arteriolar reactivity despite preserved parenchymal OIS and electrophysiological changes. These results suggest a mechanism, intrinsic to the vasculature, for propagation of vasodilatation associated with CSD. Distinct vascular conduction could be important for the pathogenesis of conditions that involve CSD, including migraine, stroke, and traumatic brain injury.