bluuebunny/crossref_metadata_2025 huggingface dataset:
A Single Amino Acid Alteration in the Human Parainfluenza Virus Type 3 Hemagglutinin-Neuraminidase Glycoprotein Confers Resistance to the Inhibitory Effects of Zanamivir on Receptor Binding and Neuraminidase Activity
Authors: Murrell Matthew T. , Porotto Matteo , Greengard Olga , Poltoratskaia Natalia , Moscona Anne
Published: July 2002

Entry and fusion of human parainfluenza virus type 3 (HPF3) requires interaction of the viral hemagglutinin-neuraminidase (HN) glycoprotein with its sialic acid receptor. 4-Guanidino-2,4-dideoxy-2,3-dehydro-
N
-acetylneuraminic acid (4-GU-DANA; zanamivir), a sialic acid transition-state analog designed to fit the influenza virus neuraminidase catalytic site, possesses antiviral activity at nanomolar concentrations in vitro. We have shown previously that 4-GU-DANA also inhibits both HN-mediated binding of HPF3 to host cell receptors and HN's neuraminidase activity. In the present study, a 4-GU-DANA-resistant HPF3 virus variant (ZM1) was generated by serial passage in the presence of 4-GU-DANA. ZM1 exhibited a markedly fusogenic plaque morphology and harbored two HN gene mutations resulting in two amino acid alterations, T193I and I567V. Another HPF3 variant studied in parallel, C-0, shared an alteration at T193 and exhibited similar plaque morphology but was not resistant to 4-GU-DANA. Neuraminidase assays revealed a 15-fold reduction in 4-GU-DANA sensitivity for ZM1 relative to the wild type (WT) and C-0. The ability of ZM1 to bind sialic acid receptors was inhibited 10-fold less than for both WT and C-0 in the presence of 1 mM 4-GU-DANA. ZM1 also retained infectivity at 15-fold-higher concentrations of 4-GU-DANA than WT and C-0. A single amino acid alteration at HN residue 567 confers these 4-GU-DANA-resistant properties. An understanding of ZM1 and other escape variants provides insight into the effects of this small molecule on HN function as well as the role of the HN glycoprotein in HPF3 pathogenesis.
Cellular Membrane-Binding Ability of the C-Terminal Cytoplasmic Domain of Human Immunodeficiency Virus Type 1 Envelope Transmembrane Protein gp41
Authors: Chen Steve S.-L. , Lee Sheau-Fen , Wang Chin-Tien
Published: July 2002

The amphipathic α-helices located in the cytoplasmic tail of the envelope (Env) transmembrane glycoprotein gp41 of human immunodeficiency virus type 1 have been implicated in membrane association and cytopathicity. Deletion of the last 12 amino acids in the C terminus of this domain severely impairs infectivity. However, the nature of the involvement of the cytoplasmic tail in Env-membrane interactions in cells and the molecular basis for the defect in infectivity of this mutant virus are still poorly understood. In this study we examined the interaction of the cytoplasmic tail with membranes in living mammalian cells by expressing a recombinant cytoplasmic tail fragment and anEscherichia coliβ-galactosidase/cytoplasmic tail fusion protein, both of them lacking gp120, the gp41 ectodomain, and the transmembrane region. We found through cell fractionation, in vivo membrane flotation, and confocal immunofluorescence studies that the cytoplasmic tail contained determinants to be routed to a perinuclear membrane region in cells. Further mapping showed that each of the three lentivirus lytic peptide (LLP-1, LLP-2, and LLP-3) sequences conferred this cellular membrane-targeting ability. Deletion of the last 12 amino acids from the C terminus abolished the ability of the LLP-1 motif to bind to membranes. High salt extraction, in vitro transcription and translation, and posttranslational membrane binding analyses indicated that the β-galactosidase/LLP fusion proteins were inserted into membranes via the LLP sequences. Subcellular fractionation and confocal microscopy studies revealed that each of the LLP motifs, acting in a position-independent manner, targeted non-endoplasmic reticulum (ER)-associated β-galactosidase and enhanced green fluorescence protein to the ER. Our study provides a basis for the involvement of the gp41 cytoplasmic tail during Env maturation and also supports the notion that the membrane apposition of the C-terminal cytoplasmic tail plays a crucial role in virus-host interaction.
The R3 Region, One of Three Major Repetitive Regions of Human Herpesvirus 6, Is a Strong Enhancer of Immediate-Early Gene U95
Authors: Takemoto Masaya , Shimamoto Takuya , Isegawa Yuji , Yamanishi Koichi
Published: July 2002

An immediate-early (IE) gene of human herpesvirus 6 (HHV-6), U95, has similarity at the amino acid level to the murine cytomegalovirus (MCMV) IE2 gene and is related to the human cytomegalovirus (HCMV) US22 gene family. Sequence analyses of U95 cDNA clones revealed that the transcription start site was located about 1.6 kbp upstream of the putative initiating ATG and that the transcript consisted of two exons. A single intron extended from nucleotides 142589 to 144229, which contained ORF U94. A protein with a molecular mass of about 120 kDa was translated from this cDNA clone in an in vitro transcription-translation assay. The transcription start site was found to be 220 bp downstream of the R3 region by primer extension analysis. HHV-6 has three repetitive elements, R1, R2, and R3, in or near the IE-A locus. R3 is composed of 24 copies of a 104- to 107-bp sequence element, which contains multiple putative binding sites for cellular transcription factors such as AP2 and NF-κB, and its biological significance has yet to be elucidated. The region between −710 and +46 relative to the transcription start site of U95 was analyzed in this study. Deletion from −710 to −396, corresponding to three copies of an R3 unit, decreased the promoter activity by 15-fold, and coexpression of IκBα(S32A/S36A) repressed it to almost the same level. Electrophoretic mobility shift assays showed that NF-κB family members p50 and c-Rel bound to NF-κB sites derived from the R3 region. These results demonstrate that R3 strongly enhances the U95 promoter activity and that NF-κB and binding sites for NF-κB in the R3 region play an important role in its activation. Because U95 promoter activity correlated with the number of R3 units, which each contained an NF-κB site, the repetitive organization of R3 is important for regulating U95 transcription.
Functional and Antigenic Characterization of Human, Rhesus Macaque, Pigtailed Macaque, and Murine DC-SIGN
Authors: Baribaud Frédéric , Pöhlmann Stefan , Sparwasser Tim , Kimata Monica T. Yu , Choi Yang-Kyu , Haggarty Beth S. , Ahmad Navid , Macfarlan Todd , Edwards Terri G. , Leslie George J. , Arnason Jon , Reinhart Todd A. , Kimata Jason T. , Littman Dan R. , Hoxie James A. , Doms Robert W.
Published: July 2002

DC-SIGN, a type II membrane protein with a C-type lectin binding domain that is highly expressed on mucosal dendritic cells (DCs) and certain macrophages in vivo, binds to ICAM-3, ICAM-2, and human and simian immunodeficiency viruses (HIV and SIV). Virus captured by DC-SIGN can be presented to T cells, resulting in efficient virus infection, perhaps representing a mechanism by which virus can be ferried via normal DC trafficking from mucosal tissues to lymphoid organs in vivo. To develop reagents needed to characterize the expression and in vivo functions of DC-SIGN, we cloned, expressed, and analyzed rhesus macaque, pigtailed macaque, and murine DC-SIGN and made a panel of monoclonal antibodies (MAbs) to human DC-SIGN. Rhesus and pigtailed macaque DC-SIGN proteins were highly similar to human DC-SIGN and bound and transmitted HIV type 1 (HIV-1), HIV-2, and SIV to receptor-positive cells. In contrast, while competent to bind virus, murine DC-SIGN did not transmit virus to receptor-positive cells under the conditions tested. Thus, mere binding of virus to a C-type lectin does not necessarily mean that transmission will occur. The murine and macaque DC-SIGN molecules all bound ICAM-3. We mapped the determinants recognized by a panel of 16 MAbs to the repeat region, the lectin binding domain, and the extreme C terminus of DC-SIGN. One MAb was specific for DC-SIGN, failing to cross-react with DC-SIGNR. Most MAbs cross-reacted with rhesus and pigtailed macaque DC-SIGN, although none recognized murine DC-SIGN. Fifteen of the MAbs recognized DC-SIGN on DCs, with MAbs to the repeat region generally reacting most strongly. We conclude that rhesus and pigtailed macaque DC-SIGN proteins are structurally and functionally similar to human DC-SIGN and that the reagents that we have developed will make it possible to study the expression and function of this molecule in vivo.
Functional Impairment of Simian Immunodeficiency Virus-Specific CD8+T Cells during the Chronic Phase of Infection
Authors: Vogel Thorsten U. , Allen Todd M. , Altman John D. , Watkins David I.
Published: July 2002

In an attempt to determine why high frequencies of circulating virus-specific CD8+T cells are unable to control human immunodeficiency virus and simian immunodeficiency virus (SIV) replication, we assessed the functional nature of SIV-specific CD8+lymphocytes. After vaccination and early after infection, nearly all tetramer-staining CD8+cells produced gamma interferon in response to their specific stimulus. However, by 4 months postinfection with pathogenic SIVmac239, signs of functional impairment in the CD8+T-cell compartment were detected which might prevent these T cells from efficiently controlling the infection during the chronic phase.
Interferons Mediate Terminal Differentiation of Human Cortical Thymic Epithelial Cells
Authors: Vidalain Pierre-Olivier , Laine David , Zaffran Yona , Azocar Olga , Servet-Delprat Christine , Wild T. Fabian , Rabourdin-Combe Chantal , Valentin Hélène
Published: July 2002

In the thymus, epithelial cells comprise a heterogeneous population required for the generation of functional T lymphocytes, suggesting that thymic epithelium disruption by viruses may compromise T-cell lymphopoiesis in this organ. In a previous report, we demonstrated that in vitro, measles virus induced differentiation of cortical thymic epithelial cells as characterized by (i) cell growth arrest, (ii) morphological and phenotypic changes, and (iii) apoptotis as a final step of this process. In the present report, we have analyzed the mechanisms involved. First, measles virus-induced differentiation of thymic epithelial cells is shown to be strictly dependent on beta interferon (IFN-β) secretion. In addition, transfection with double-stranded RNA, a common intermediate of replication for a broad spectrum of viruses, is reported to similarly mediate thymic epithelial cell differentiation through IFN-β induction. Finally, we demonstrated that recombinant IFN-α, IFN-β, or IFN-γ was sufficient to induce differentiation and apoptosis of uninfected thymic epithelial cells. These observations suggested that interferon secretion by either infected cells or activated leukocytes, such as plasmacytoid dendritic cells or lymphocytes, may induce thymic epithelium disruption in a pathological context. Thus, we have identified a new mechanism that may contribute to thymic atrophy and altered T-cell lymphopoiesis associated with many infections.
Persistence and Fitness of Multidrug-Resistant Human Immunodeficiency Virus Type 1 Acquired in Primary Infection
Authors: Brenner Bluma G. , Routy Jean-Pierre , Petrella Marco , Moisi Daniela , Oliveira Maureen , Detorio Mervi , Spira Bonnie , Essabag Vidal , Conway Brian , Lalonde Richard , Sekaly Rafick-Pierre , Wainberg Mark A.
Published: July 2002

This study examines the persistence and fitness of multidrug-resistant (MDR) viruses acquired during primary human immunodeficiency virus infection (PHI). In four individuals, MDR infections persisted over the entire study period, ranging from 36 weeks to 5 years, in the absence of antiretroviral therapy. In stark contrast, identified source partners in two cases showed expected outgrowth of wild-type (WT) virus within 12 weeks of treatment interruption. In the first PHI case, triple-class MDR resulted in low plasma viremia (1.6 to 3 log copies/ml) over time compared with mean values obtained for an untreated PHI group harboring WT infections (4.1 to 4.3 log copies/ml). Increasing viremia in PHI patient 1 at week 52 was associated with the de novo emergence of a protease inhibitor-resistant variant through a recombination event involving the original MDR virus. MDR infections in two other untreated PHI patients yielded viremia levels typical of the untreated WT group. A fourth patient's MDR infection yielded low viremia (<50 to 500 copies/ml) for 5 years despite his having phenotypic resistance to all antiretroviral drugs in his treatment regimen. In two of these PHI cases, a rebound to higher levels of plasma viremia only occurred when the M184V mutation in reverse transcriptase could no longer be detected and, in a third case, nondetection of M184V was associated with an inability to isolate virus. To further evaluate the fitness of MDR variants acquired in PHI, MDR and corresponding WT viruses were isolated from index and source partners, respectively. Although MDR viral infectivity (50% tissue culture infective dose) was comparable to that observed for WT viruses, MDR infections in each case demonstrated 2-fold and 13- to 23-fold reductions in p24 antigen and reverse transcriptase enzymatic activity, respectively. In dual-infection competition assays, MDR viruses consistently demonstrated a marked replicative disadvantage compared with WT virus. These results indicate that MDR viruses that are generated following PHI can establish persistent infections as dominant quasispecies despite their impaired replicative competence.
B7 Costimulation Plays an Important Role in Protection from Herpes Simplex Virus Type 2-Mediated Pathology
Authors: Thebeau Lydia G. , Morrison Lynda A.
Published: July 2002

We have used mice lacking both B7-1 and B7-2 costimulation molecules (B7KO) to investigate the effects of B7 costimulation on herpes simplex virus type 2 (HSV-2) pathogenesis. B7KO mice infected intravaginally with virulent HSV-2 showed more severe genital and neurologic disease and higher mortality rates than their wild-type counterparts. These results suggest that B7 costimulation molecules play an important role in the development of primary immune responses protective against HSV-2.
In Vivo Interference of Rous Sarcoma Virus Budding by
cis
Expression of a WW Domain
Authors: Patnaik Akash , Wills John W.
Published: July 2002

For all enveloped viruses, the actual mechanism by which nascent virus particles separate or “pinch off” from the cell surface is largely unknown. In the case of retroviruses, the Gag protein drives the budding process, and the virus release step is directed by the late (L) assembly domain within Gag. A PPPPY motif within the L domain of Rous sarcoma virus (RSV) was previously characterized as being critical for the release of virions and shown to interact in vitro with the WW domain of Yes-associated protein (Yap). To determine whether WW domain-L domain interactions can occur in vivo, we attempted to interfere with the host cell machinery normally recruited to the site of budding by inserting this WW domain in different locations within Gag. At a C-terminal location, the WW
Yap
domain had no effect on budding, suggesting that the intervening I domains (which provide the major region of Gag-Gag interaction) prevent its access to the L domain. When positioned on the other side of the I domains closer to the L domain, the WW
Yap
domain resulted in a dramatic interference of particle release, and confocal microscopy revealed a block to budding on the plasma membrane. Budding was restored by attachment of the heterologous L domain of human immunodeficiency virus type 1 Gag, which does not bind WW
Yap
. These findings suggest that
cis
expression of WW domains can interfere with RSV particle release in vivo via specific, high-affinity interactions at the site of assembly on the plasma membrane, thus preventing host factor accessibility to the L domain and subsequent virus-cell separation. In addition, they suggest that L domain-specific host factors function after Gag proteins begin to interact.
Parametrization of the Scaling Factor in the Quasi-Relativistic INDO Method Based on the Equilibrium Geometries and Vibrational Frequencies of Electroneutral Closed-Shell XY4 Molecules Possessing the Td Symmetry
Authors: Turi Nagy Ladislav , Liška Marek , Tunega Daniel
Published: July 2002

The parameter K in the quasi-relativistic INDO (QR-INDO) relation hiAjBcore = 1/2 K Si,j (βiA + βjB) was optimized by applying the QR-INDO method to the optimization of the geometries and calculation of vibrational wavenumbers of 36 molecules of the XY4 type with X = C, Si, Ti, Ge, Zr, Sn, Hf and Pb, and Y = H, F, Cl, Br and I. The calculations were performed for 10 values of K uniformly spaced across the region of 1.1 to 2.0. The optimum value with which the best fit of the bond lengths and vibrational frequencies was achieved was K = 1.5. This is very close to the value of 1.4 recommended in the literature. The study was performed using recent tabulated gas-phase data. The application of the variable scaling approximation approach was found generally unsuitable.
Diffusion Dialysis of Sulfuric Acid in a Batch Cell
Authors: Palatý Zdeněk , Žáková Alena
Published: July 2002

The paper deals with the diffusion dialysis of sulfuric acid into water in a batch cell with a Neosepta-AFN anionselective membrane. The transport of sulfuric acid through the membrane has been quantified with respect to the dissociation of the acid by the dialysis coefficients for HSO4- and SO42- ions. These coefficients have been determined by numerical integration of the basic differential equation describing the time dependence of sulfuric acid concentration in the dialysis cell with subsequent optimization of dialysis coefficients. Moreover, the membrane permeability coefficients for HSO4- and SO42- ions and nondissociated sulfuric acid have been determined by the modified method of the Wilson diagram using the data about mass transfer in liquid for the given geometrical arrangement of cell.
Certain Problems with the Application of Stochastic Diffusion Processes for the Description of Chemical Engineering Phenomena. Numerical Simulation of One-Dimensional Diffusion Process
Authors: Hasal Pavel , Kudrna Vladimír
Published: July 2002

Some problems are analyzed arising when a numerical simulation of a random motion of a large ensemble of diffusing particles is used to approximate the solution of a one-dimensional diffusion equation. The particle motion is described by means of a stochastic differential equation. The problems emerging especially when the diffusion coefficient is a function of spatial coordinate are discussed. The possibility of simulation of various kinds of stochastic integral is demonstrated. It is shown that the application of standard numerical procedures commonly adopted for ordinary differential equations may lead to erroneous results when used for solution of stochastic differential equations. General conclusions are verified by numerical solution of three stochastic differential equations with different forms of the diffusion coefficient.
Catalytic Hydrogenation of Acetophenone Over Ruthenium Catalysts
Authors: Červený Libor , Dobrovolná Zuzana , Bělohlav Zdeněk , Klusoň Petr
Published: July 2002

Catalytic hydrogenation of acetophenone in ethanol was studied by using 5 wt.% Ru supported on active carbon, alumina, and titania. Parameters of kinetic equations (reaction rate constants and adsorption coefficients) were evaluated and the influence of the support on the reaction course was discussed. An enhanced selectivity of Ru/TiO2 towards carbonyl group hydrogenation with respect to the hydrogenation of the aromatic ring was confirmed.
Interaction of HIV Tat Peptides With tRNAPhe from Yeast
Authors: Buskiewicz Iwona , Giel-Pietraszuk Malgorzata , Mucha Piotr , Rekowski Piotr , Kupryszewski Gotfryd , Barciszewska Miroslawa Z.
Published: July 2002

We present data on the interaction of arginine-rich peptides of human immunodeficiency virus (HIV-Tat) with tRNAPhe of Saccharomyces cerevisiae. We have found that tRNA forms complexes with the Tat1 peptide of amino acid sequence GRKKRRQRRRA and its mutants where R is replaced by D-arginine, citrulline or ornithine. The structure of tRNA-Tat1 complex was probed by specific RNases digestions and Pb2+-induced cleavage of phosphodiester bond of guanosine. The nucleotide sequence UGGG located in the dihydrouridine loop of tRNAPhe binds to Tat peptide and therefore is specifically protected against RNases and is not hydrolyzed by Pb2+ ion. It seems that the peptide-RNA complex formation depends on direct recognition of guanine moieties of tRNA with arginine residues. These interactions are similar to those observed in many DNA-protein complexes, but are different from those previously observed for TAR RNA-Tat complexes.
Effect of Liquid Axial Mixing on Local kLa Values in Individual Stages of Multiple-Impeller Vessel
Authors: Moucha Tomáš , Linek Václav , Sinkule Jiří
Published: July 2002

The effect of the liquid phase axial mixing on rlocalr kLa values, measured by dynamic pressure method (DPM), in individual stages of multiple-impeller vessel is evaluated. The data measured by the DPM in our previous papers are corrected for this effect. Various calculation methods for kLa in the upper stages based on single-impeller vessel correlations are compared.
Free Convective Mass Transfer at Down-Pointing Isosceles Triangles of Varying Inclination
Authors: Krýsa Josef , Iino Fukuya , Wragg Anthony A.
Published: July 2002

Free convective mass transfer at down-pointing triangular surfaces of different length and down-facing inclination was investigated using the limiting diffusion current technique of mass transfer measurement. The mass transfer rate was observed to be higher for a down-pointing triangular inclined surface over the entire range of inclination than that for an inclined rectangular surface because of the different rleading edger condition. A mass transfer correlation for down-facing inclined triangular surfaces of different length was found to be ShL = 0.774(RaL cos θ)0.25 for the RaL cos θ range from 2 . 106 to 2 . 1011.
Nickel(0) and Palladium(0) Complexes with (Z,Z)-Ph2PCH2C(t-Bu)=N-N=C(t-Bu)CH2PPh2. Alkyne-to-Alkenyl Conversion in [Pd(MeOCOCCCOOMe){(Z,Z)-Ph2PCH2C(t-Bu)=N-N=C(t-Bu)CH2PPh2}]
Authors: Čermák Jan , Šabata Stanislav , Blechta Vratislav , Shaw Bernard L.
Published: July 2002

Novel zero-valent metal complexes [ML2{(Z,Z)-Ph2PCH2C(t-Bu)=N-N=C(t-Bu)CH2PPh2}] (M = Ni, L = CO, t-BuNC) with the azine diphosphine chelating in a nine-membered ring were prepared. The nickel dicarbonyl complex was found to be in an equilibrium with its isomer containing (E,Z)-chelated azine diphosphine, the equilibrium being on the side of the (Z,Z)-isomer below 60 °C. A similar palladium complex (M = Pd, L2 = CH3OCOC≡CCOOCH3) prepared earlier was found to undergo a rearrangement with simultaneous alkyne-to-alkenyl conversion of the acetylenedicarboxylate dimethyl ester ligand.
Genetic alterations and growth pattern in biliary duct carcinomas: loss of heterozygosity at chromosome 5q bears a close relation with polypoid growth
Authors: Hidaka E , Yanagisawa A , Seki M , Setoguchi T , Kato Y
Published: July 2002

Biliary duct carcinomas (BDCs) are relatively rare and the carcinogenic mechanisms underlying their induction are poorly understood. There are two growth patterns, polypoid and non-polypoid infiltrative type, but little information is available concerning the relation between growth pattern and genetic alterations. A comparative study was therefore conducted to clarify if differences in genetic changes, including loss of heterozygosity (LOH) at 5q, 9p, 17p, and 18q, and K-ras mutations exist between polypoid and non-polypoid infiltrative type BDCs. LOH analysis was performed using microsatellite markers and K-ras point mutations were analysed by dot blot hybridisation. The incidences of changes for polypoid and non-polypoid infiltrative types were 73% and 26% on 5q, 63% and 59% on 9p, 55% and 50% on 17p, and 20% and 18% on 18q, and 25% and 27% for K-ras mutations. Most importantly, we found the frequency of 5qLOH to be significantly higher with polypoid growth than in the non-polypoid infiltrative type (p<0.05), especially in extrahepatic duct carcinomas (p<0.05). The incidences of other genetic alterations (LOH at 9p, 17p, and 18q, and K-ras mutations) showed similar rates with both tumour types. The present data suggest that 5qLOH may have a close relation with polypoid growth in BDCs.
School smoking policies and smoking prevalence among adolescents: multilevel analysis of cross-sectional data from Wales
Authors: Moore Laurence , Roberts Chris , Tudor-Smith Chris
Published: July 2002

OBJECTIVE

To examine the association between school smoking policies and smoking prevalence among pupils.

DESIGN

Multilevel analysis of cross-sectional data from surveys of schools and pupils.

SETTING

55 secondary schools in Wales.

SUBJECTS

55 teachers and 1375 pupils in year 11 (aged 15–16).

MAIN OUTCOME MEASURES

Self-reported smoking behaviour.

RESULTS

The prevalence of daily smoking in schools with a written policy on smoking for pupils, teachers, and other adults, with no pupils or teachers allowed to smoke anywhere on the school premises, was 9.5% (95% confidence interval (CI) 6.1% to 12.9%). In schools with no policy on pupils' or teachers' smoking, 30.1% (95% CI 23.6% to 36.6%) of pupils reported daily smoking. In schools with an intermediate level of smoking policy, 21.0% (95% CI 17.8% to 24.2%) smoked every day. School smoking policy was associated with school level variation in daily smoking (p = 0.002). In multilevel analysis, after adjusting for pupils' sex, parents' and best friends' smoking status, parental expectations, and alienation from school, there was less unexplained school level variation, but school smoking policy remained significant (p = 0.041). The association of smoking policy with weekly smoking was weaker than for daily smoking, and not significant after adjustment for pupil level variables. Both daily and weekly smoking prevalence were lower in schools where pupils' smoking restrictions were always enforced. Enforcement of teacher smoking restrictions was not significantly associated with pupils' smoking.

CONCLUSIONS

This study demonstrates an association between policy strength, policy enforcement, and the prevalence of smoking among pupils, after having adjusted for pupil level characteristics. These findings suggest that the wider introduction of comprehensive school smoking policies may help reduce teenage smoking.
On the Super-Unitarity of Discrete Series Representations of Orthosymplectic Lie Superalgebras
Authors: El Gradechi Amine M.
Published: July 2002

We investigate the notion of super-unitarity from a functional analytic point of view. For this purpose we consider examples of explicit realizations of a certain type of irreducible representations of low rank orthosymplectic Lie superalgebras which are super-unitary by construction. These are the so-called superholomorphic discrete series representations of osp (1/2,ℝ) and osp (2/2,ℝ) which we recently constructed using a ℤ2–graded extension of the orbit method. It turns out here that super-unitarity of these representations is a consequence of the self-adjointness of two pairs of anticommuting operators which act in the Hilbert sum of two Hilbert spaces each of which carrying a holomorphic discrete series representation of su (1,1) such that the difference of the respective lowest weights is [Formula: see text]. At an intermediate stage, we show that the generators of the considered orthosymplectic Lie superalgebras can be realized either as matrix-valued first order differential operators or as first order differential superoperators. Even though the former realization is less convenient than the latter from the computational point of view, it has the advantage of avoiding the use of anticommuting Grassmann variables, and is moreover important for our analysis of super-unitarity. The latter emphasizes the fundamental role played by the atypical (or degenerate) superholomorphic discrete series representations of osp (2/2,ℝ) for the super-unitarity of the other representations considered in this work, and shows that the anticommuting (unbounded) self-adjoint operators mentioned above anticommute in a proper sense, thus connecting our work with the analysis of supersymmetric quantum mechanics.
CHAOTIC BEHAVIOR AND CHAOS CONTROL FOR A CLASS OF COMPLEX PARTIAL DIFFERENTIAL EQUATIONS
Authors: MAHMOUD G. M. , ABDUSALAM H. A. , FARGHALY A. A. M.
Published: July 2002

Systems of complex partial differential equations, which include the famous nonlinear Schrödinger, complex Ginzburg–Landau and Nagumo equations, as examples, are important from a practical point of view. These equations appear in many important fields of physics. The goal of this paper is to concentrate on this class of complex partial differential equations and study the fixed points and their stability analytically, the chaotic behavior and chaos control of their unstable periodic solutions. The presence of chaotic behavior in this class is verified by the existence of positive maximal Lyapunov exponent.The problem of chaos control is treated by applying the method of Pyragas. Some conditions on the parameters of the systems are obtained analytically under which the fixed points are stable (or unstable).
KINETICS OF MUON CATALYZED FUSION IN D/T/H MIXTURE CONSIDERING MUON TRANSFER FROM HYDROGEN ISOTOPES TO HELIUM ISOTOPES
Authors: HATEF A. , HOSEINI MOTLAGH S. N. , NIAD H.
Published: July 2002

In this paper the kinetics of Muon Catalyzed Fusion (μCF) in H/D/T mixture, considering the muon transfer from hydrogen isotopes (p,d,t) to helium isotopes (3 He , 4 He ) in the range of temperatures of 300 K < T < 1300 K at the density of Φ = 1 LHD, is presented. Calculation of cycling rate in different branches of fusion such as dtμ, ptμ, pdμ, ddμ, ttμ and energy gain showed that in certain physical conditions, the H/D/T mixture is comparable to D/T one. Finally the results of this research are compared with the experimental results reported by other researchers; and good agreements were found.
A CLASS OF EXACT SOLUTIONS OF THE TIME-DEPENDENT SCHRÖDINGER EQUATION WITH TIME-DEPENDENT MASS
Authors: SCHULZE-HALBERG AXEL
Published: July 2002

We obtain a large class of solvable potentials and the corresponding exact solutions of the time-dependent Schrödinger equation with time-dependent mass by transforming it into an equation of telegraphy.
AN EXPERIMENTALIST'S VIEW OF NEUTRINO OSCILLATIONS
Authors: DE SANTO ANTONELLA
Published: July 2002

Neutrinos, and primarily neutrino oscillations, have undoubtedly been one of the most exciting topics in the field of high-energy physics over the past few years. The existence of neutrino oscillations would require an extension of the currently accepted description of sub-nuclear phenomena beyond the Standard Model. Compelling evidence of new physics, which seems to be pointing towards neutrino oscillations, is coming from the solar neutrino deficit and from the atmospheric neutrino anomaly. More controversial effects have been observed with artificially produced neutrinos. The present experimental status of neutrino oscillations is reviewed, as well as the planned future experimental programme, which, it is hoped, will solve most of the outstanding puzzles.
Probing the Infrared Structure of Gauge Theories: A Padé-Approximant Approach
Authors: Chishtie F. A. , Elias V. , Miransky V. A. , Steele T. G.
Published: July 2002

Padé-approximant treatments of the known terms of the QCD β-function are seen to develop possible infrared fixed point structure only if the number of fermion flavours is sufficiently large. This flavour threshold is seen to be between six and nine flavours, depending upon both the specific choice of approximant as well as on the presently-unknown five-loop β-function contribution. Below this flavour threshold, Padé approximants based upon the QCD β-function manifest the same infrared attractor structure as that which characterizes the exact NSVZ β-function of supersymmetric gluodynamics. Such infrared attractor structure is also seen to characterize Padé-approximant treatments of vector SU(N) gauge theory in the large N limit, suggesting common infrared dynamics for the strong and weak phases of this theory.
DIFFEOMORPHISM, HAMILTONIAN CONSTRAINTS AND MANDELSTAM IDENTITIES OVER EXTENDED KNOT FAMILIES $\{\psi_i\}_2^2$ AND $\{\psi_i\}_3^4$
Authors: SHAO D. , NODA H. , SHAO L. , SHAO C. G.
Published: July 2002

The calculations of the extended knot families [Formula: see text] and [Formula: see text] to satisfy the diffeomorphism constraint, Hamiltonian constraint and Mandelstam identities are given in the extended loop representation.
SOME PROPERTIES OF THE TRANSVERSE ELASTIC WAVES IN QUASIPERIODIC STRUCTURES
Authors: TUTOR J. , VELASCO V. R.
Published: July 2002

We have studied the integrated density of states and fractal dimension of the transverse elastic waves spectrum in quasiperiodic systems following the Fibonacci, Thue–Morse and Rudin–Shapiro sequences. Due to the finiteness of the quasiperiodic generations, in spite of the high number of materials included, we have studied the possible influence of the boundary conditions, infinite periodic or finite systems, together with that of the different ways to generate the constituent blocks of the quasiperiodic systems, on the transverse elastic waves spectra. No relevant differences have been found for the different boundary conditions, but the different ways of generating the building blocks produce appreciable consequences in the properties of the transverse elastic waves spectra of the quasiperiodic systems studied here.
FIRST OBSERVATION OF DYNAMIC INTENSITY BORROWING INDUCED BY COHERENT MOLECULAR VIBRATIONS IN J-AGGREGATES REVEALED BY SUB-5-FS SPECTROSCOPY
Authors: KANO HIDEAKI , SAITO TAKASHI , UEKI AKIKATSU , KOBAYASHI TAKAYOSHI
Published: July 2002

Sub-5-fs spectroscopy of porphyrin J-aggregates reveals for the first time coherent molecular vibration coupled to the Frenkel exciton. The oscillations with the frequency of 244cm-1 are described by a plus-cosine function for bleaching and a minus-cosine function for induced absorption. The coherent oscillation is explained by a modulated transition dipole moment, which is due to the transfer of an oscillator strength from the intense B-band to the weak Q-band through the ruffling mode with 244cm-1-frequency.
Relationship between Conductivity and Phase Coherence Length in Cuprates
Authors: ALMASAN C. C. , LEVIN G. A. , CIMPOIASU E. , STEIN T. , ZHANG C. L. , DEANDRADE M. C. , MAPLE M. B. , ZHENG HONG , PAULIKAS A. P. , VEAL B. W.
Published: July 2002

The large (102–105) and strongly temperature dependent resistive anisotropy η=(σab/σc)1/2 of cuprates perhaps holds the key to understanding their normal state in-plane σab and out-of-plane σc conductivities. It can be shown that η is determined by the ratio of the phase coherence lenghts ℓi in the respective directions: [Formula: see text]. In layered crystals in which the out-of-plane transport is incoherent, ℓc is fixed, equal to the interlayer spacing. As a result, the T-dependence of η is determined by that of ℓab, and vice versa, the in-plane phase coherence lenght can be obtained directly by measuring the resistive anisotropy. We present data for hole-doped YBa2Cu3Oy (6.3<y<6.9) and Y1-xPrxBa2O7-δ(0<x≤0.55) and show that σcb of crystals with different doping levels can be well described by a two parameter universal function of the in-plane phase coherence length. In the electron-doped Nd2-xCexCuO4-y, the dependence σab(η) indicates a crossover from incoherent transport in the c-direction.
DISSIPATION IN GRANULAR Bi1.7Pb0.3Sr2Ca2Cu3Ox
Authors: BHALLA G. L.
Published: July 2002

Dissipation in high-T c superconducting Bi 1.7 Pb 0.3 Sr 2 Ca 2 Cu 3 O x samples in different magnetic fields has been investigated in terms of the modified Ambegaokar–Halperin theory. Our observed dissipation behaviour in the transition region is well described on this model by employing two exponents instead of one. Curiously, each resistance–temperature curve seems to possess mainly two different regions, which, we believe, can be accounted for in terms of order parameter fluctuations and vortex dynamics. A new dissipation mechanism transition temperature T BP has been observed, across which one dissipation mechanism possibly changes over to another mechanism.
GAUSSIAN DOMINATION IN A QUANTUM SYSTEM OF NONLINEAR OSCILLATORS
Authors: CORGINI M. , SANKOVICH D. P.
Published: July 2002

A quantum system of nonlinear oscillators is considered. Within the framework of Berezin's functional integral we prove the gaussian domination at finite temperature for some values of the chemical potential. Upper and lower bounds for the average number of particles with momentum p are derived.
LEVEL STABILITY OF THE QUANTUM DOTS WITH IMPURITY
Authors: HUANG YUNG-SHENG , LIAW SY-SANG
Published: July 2002

An atom located at the center of the constant spherical potential is adopted as a simple model for a quantum dot with impurity. We find that, under this model, the stability of the energy levels of a quantum dot with impurity can be controlled by adjusting either the size or the band gap of the quantum dot.
STABLE STATIONARY SOLUTIONS IN REACTION–DIFFUSION SYSTEMS CONSISTING OF A 1-D ARRAY OF BISTABLE CELLS
Authors: NIZHNIK LEONID P. , NIZHNIK IRINA L. , HASLER MARTIN
Published: July 2002

In this paper we present the construction of stable stationary solutions in reaction–diffusion systems consisting of a 1-D array of bistable cells with a cubic nonlinearity and with a cubic-like piecewise-linear nonlinearity. Some periodic solutions, kinks, solitons are considered. While it is known that spatial chaos arises in such systems with small coupling constants, we show the existence of spatial chaos for an arbitrary value of the cell coupling constant, in the case of the piecewise-linear nonlinearity. The value of the spatial entropy is found. We also show the existence of stable spatially periodic (pattern) solutions that persist for large coupling constants.
BIFURCATION ANALYSIS OF TIME-DELAY CONTROL SYSTEMS WITH SATURATION
Authors: PAGANO DANIEL J. , PONCE ENRIQUE , ARACIL JAVIER
Published: July 2002

A frequency domain approach to the bifurcation analysis of time-delay SISO control systems with saturation is proposed. Generic bifurcations to be expected for these systems are emphasized. The main goal is to give a classification of system behavior modes that are relevant for stability studies, reaching a global perspective of the parameter space. The classification is obtained through the bifurcation analysis, which is implemented by frequency domain methods that are well known to the control systems engineers. Some specific cases are analyzed with this methodology. The theoretical results are in agreement with numerical simulations.
DECISION AND SEPARABILITY PROBLEMS FOR BAUMSLAG–SOLITAR SEMIGROUPS
Authors: JACKSON DAVID A.
Published: July 2002

We show that the semigroups Sk,ℓhaving semigroup presentations  are residually finite and finitely separable. Generally, these semigroups have finite separating images which are finite groups and other finite separating images which are semigroups of order-increasing transformations on a finite partially ordered set. These semigroups thus have vastly different residual and separability properties than the Baumslag–Solitar groups which contain them.
NEW INVARIANTS FOR GROUPS
Authors: CRUICKSHANK D. A. , PRIDE S. J.
Published: July 2002

The aim of this paper is to begin the development of a theory of higher-dimensional Alexander ideals for groups. The classical Alexander ideals of a finitely generate group take the form of an ascending chain of ideals in a commutative ring. For a group of type FPn, we define a group invariant in every dimension up to n, also in the form of a chain of ideals, the ideals in dimension 1 being precisely the chain of Alexander ideals. We show how these invariants can be calculated for certain groups, such as R. Thompson's group, (relatively) aspherical groups and graphs of groups, and we demonstrate that the higher-dimension invariants can distinguish groups which the classical Alexander ideals cannot.

We also define Alexander-type ideals for modules as well as a number of secondary group invariants in the form of polynomials and 'ranks', which are connected with work of Swan, Hattori and Stallings, K. S. Brown and Lustig. Finally, we explain how this theory can be extended to monoids.
COMPUTATIONAL COMPLEXITY OF TERM-EQUIVALENCE
Authors: BERGMAN CLIFFORD , JUEDES DAVID , SLUTZKI GIORA
Published: July 2002

Two algebraic structures with the same universe are called term-equivalent if they have the same clone of term operations. We show that the problem of determining whether two finite algebras of finite similarity type are term-equivalent is complete for deterministic exponential time.
FORBIDDEN MOVES UNKNOT A VIRTUAL KNOT
Authors: KANENOBU TAIZO
Published: July 2002

We show that any virtual knot can be deformed into a trivial knot by a finite sequence of generalized Reidemeister moves and "forbidden moves". We also show that a Δ-unknotting operation is realized by a finite sequence of generalized Reidemeister moves and "forbidden moves".
ONE PARAMETER SOLUTION OF SPHERICALLY SYMMETRIC ACCRETION IN VARIOUS PSEUDO-SCHWARZSCHILD POTENTIALS
Authors: SARKAR AVEEK , DAS TAPAS K.
Published: July 2002

In this paper we have solved the hydrodynamic equations governing the spherically symmetric isothermal accretion (wind) onto (away from) compact objects using various pseudo-Schwarzschild potentials. These solutions are essentially one parameter solutions in a sense that all relevant dynamical as well as thermodynamic quantities for such a flow could be obtained (with the assumption of a one-temperature fluid) if only one flow parameter (temperature of the flow T) is given. Also we have investigated the transonic behaviour of such a flow and showed that for a given T, transitions from subsonic to the supersonic branch of accretion (wind) takes place at different locations depending on the potentials used to study the flow and we have identified these transition zones for flows in various such potentials.
CMB ANISOTROPY AND POLARIZATION MEASUREMENTS WITH RATAN-600
Authors: NASELSKY P. , NOVIKOV I. , PARIJSKIJ YU. , TCIBULEV P.
Published: July 2002

Some aspects of the Cosmological Gene project and the possibilities of the measurements of the Cosmic Microwave Background (CMB) anisotropy and polarization using the radio-telescope RATAN-600 (Special Astrophysical Observatory) are discussed. We study different strategies of the measurements and present main parameters of the antenna beam for these strategies at the frequency diapason ν=1–30 GHz. We simulate Cosmological Gene observations using a standard Cold Dark Matter cosmological model. We quantify the distortions of the primordial CMB-signal in the RATAN-600 scans by the atmosphere emission, foreground and noise in RATAN-600 scans.

We emphasize that RATAN-600 is the unique instrument which allows the investigation of anisotropy and polarization of the CMB and investigate foreground and noise up to the multipole numbers l ∝ 105.
INTERMITTENCY IN 4.5A AND 14.5A GeV/c28Si-NUCLEUS INTERACTIONS
Authors: BARI W. , AHMAD N. , KHAN M. M. , AHMAD SHAKEEL , ZAFAR M. , IRFAN M.
Published: July 2002

The occurrence of intermittent patterns in 14.5 A GeV/c 28 Si -nucleus interactions is examined in terms of Scaled Factorial Moments (SFMs), introduced by Bialas and Peschanski. Further, to examine the dependence of various interesting characteristics of SFMs on incident energy, the data on 4.5 A GeV/c 28 Si -nucleus collisions available in our laboratory are analyzed. Interestingly, log-log plots between rapidity interval δη and the qth order factorial moment Fq for both the energies exhibit linear behavior indicating thereby the presence of intermittency in the interactions investigated. Moreover, to look at the fractal nature of the particle emitting sources, variation of the fractal dimensions, dq with the order of the moment is investigated. Finally, study of the variation of λq [=(ϕq+1)/q)] with the order of the moment, q indicates a possibility of non-thermal phase transition in certain types of events
MOLECULES AT SURFACES AND INTERFACES STUDIED USING VIBRATIONAL SPECTROSCOPIES AND RELATED TECHNIQUES
Authors: DUMAS P. , WELDON M. K. , CHABAL Y. J. , WILLIAMS G. P.
Published: July 2002

Recent developments in the major experimental vibrational-spectroscopic techniques (i.e. infrared absorption, Raman scattering, high resolution electron loss, helium atom scattering and sum frequency generation) are reviewed and illustrated with selected results. Particular emphasis is given to two important topics which have attracted much attention in recent years: (i) the complex surface reactions taking place on technologically relevant surfaces and interfaces, and (ii) vibrational dynamics with emphasis on energy dissipation at surfaces.
Long-Term Results After Policization for Congenital Hand Deformities
Authors: Ogino Toshihiko , Ishii Seiichi
Published: July 2002

Thirteen patients — 18 hands — have been treated with pollicization and could be followed-up for 2 years to 19 years with an average of 7.9 years. Surgery was performed according to the Buck-Gramcko method. The mean age at the time of pollicization was 1.7 years. The parents were satisfied with the cosmetic results in all cases, and they were satisfied with the functional results in all except 4 hands. At follow-up, all patients could use the pollicized digit for pinch. Excellent pinch function has been achieved in 11 hands, good in 2, and fair in 1. The average percent pinch strength compared to the opposite hand was 55%. Association of a radial club hand and contracture of the pollicized digit and other fingers seemed to influence the postoperative pinch function.
ADAPTIVE SCHEMES FOR REDUCING POWER CONSUMPTION OF MOBILE DATA HANDSETS
Authors: CHEN RONG-JAYE , LIN TING-YU , LIN YI-BING
Published: July 2002

This paper describes a threshold-based wake-up mechanism to reduce the battery power consumption of a mobile data handset. The threshold approach switches the system into the sleep mode when the memory queue for arriving packets is empty, and switches on the system when the number of packets in the memory queue is above a threshold value. We propose several adaptive schemes capable of dynamically selecting the threshold value for the threshold approach. An adaptive algorithm adjusts the threshold value based on a pre-defined packet-dropping probability, for which the switch-on rate is kept reasonably small to maintain the actual packet-dropping probability as close as the pre-defined value.

Two strategies are used in the adaptive algorithm to adjust the threshold value: binary-division and fixed-amount. Two calculation strategies are considered to measure the packet-dropping probability: window-averaging and leaky-bucket integration (LBI). Our study indicates that the binary-division strategy outperforms the fixed-amount strategy in adjusting the threshold value. Furthermore, with proper setting, the LBI strategy outperforms the window-averaging strategy.
Origins of granular memory in model sandpiles
Authors: Barker G. C. , Mehta Anita
Published: July 2002

We describe a lattice model for intermittent flow in granular materials. This model includes degrees of freedom, related to lattice grain orientations, that are additional to those associated with the coupled dynamics of columns of lattice grains. We have explored the development of granular structures in model piles and shown that the surface dynamics of lattice grains is strongly linked to relaxations of granular structures in the pile. The coupling is shown to lead to two distinct avalanche morphologies in model piles that have been disturbed from their steady state. The change of behaviour is explained in terms of the statistical properties of surface instabilities.