bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vitro Human Immunodeficiency Virus Eradication by Autologous CD8+T Cells Expanded with Inactivated-Virus-Pulsed Dendritic Cells
Authors: Lu Wei , Andrieu Jean-Marie
Published: July 2002

Despite significant immune recovery with potent highly active antiretroviral therapy (HAART), eradication of human immunodeficiency virus (HIV) from the bodies of infected individuals represents a challenge. We hypothesized that an inadequate or inappropriate signal in virus-specific antigen presentation might contribute to the persistent failure to mount efficient anti-HIV immunity in most HIV-infected individuals. Here, we conducted an in vitro study with untreated (n= 10) and HAART-treated (n= 20) HIV type 1 (HIV-1) patients which showed that pulsing of monocyte-derived dendritic cells (DC) with aldrithiol-2-inactivated autologous virus resulted in the expansion of virus-specific CD8+T cells which were capable of killing HIV-1-infected cells and eradicating the virus from cultured patient peripheral blood mononuclear cells independently of the disease stages and HAART response statuses of the patients. This in vitro anti-HIV effect was further enhanced by the HIV protease inhibitor indinavir (at a nonantiviral concentration), which has been shown previously to be able to up-regulate directly patient T-cell proliferation following immune stimulation. However, following a 2-day treatment with culture supernatant derived from immune-activated T cells (which mimics an in vivo environment of HIV-disseminated and immune-activated lymphoid tissues), DC lost their capacity to present de novo inactivated-virus-derived antigens. These findings provide important information for understanding the establishment of chronic HIV infection and indicate a perspective for clinical use of DC-based therapeutic vaccines against HIV.
Kaposi's Sarcoma-Associated Herpesvirus Latent and Lytic Gene Expression as Revealed by DNA Arrays
Authors: Jenner Richard G. , Albà M. Mar , Boshoff Chris , Kellam Paul
Published: July 2002

Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) is associated with three human tumors, Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease. KSHV encodes a number of homologs of cellular proteins involved in the cell cycle, signal transduction, and modulation of the host immune response. Of the virus complement of over 85 open reading frames (ORFs), the expression of only a minority has been characterized individually. We have constructed a nylon membrane-based DNA array which allows the expression of almost every ORF of KSHV to be measured simultaneously. A PEL-derived cell line, BC-3, was used to study the expression of KSHV during latency and after the induction of lytic replication. Cluster analysis, which arranges genes according to their expression profile, revealed a correlation between expression and assigned gene function that is consistent with the known stages of the herpesvirus life cycle. Furthermore, latent and lytic genes thought to be functionally related cluster into groups. The correlation between gene expression and function also infers possible roles for KSHV genes yet to be characterized.
Rapid Appearance of Secondary Immune Responses and Protection from Acute CD4 Depletion after a Highly Pathogenic Immunodeficiency Virus Challenge in Macaques Vaccinated with a DNA Prime/Sendai Virus Vector Boost Regimen
Authors: Matano Tetsuro , Kano Munehide , Nakamura Hiromi , Takeda Akiko , Nagai Yoshiyuki
Published: July 2002

Heterologous prime/boost regimens are AIDS vaccine candidates because of their potential for inducing cellular immune responses. Here, we have developed a prime/boost regimen leading to rapid control of highly pathogenic immunodeficiency virus infection in macaques. The strategy, priming by an
env
and
nef
deletion-containing simian-human immunodeficiency virus (SHIV) proviral DNA followed by a single booster with a Gag-expressing Sendai virus (SeV-Gag), efficiently induced virus-specific T cells, which were maintained for more than 3 months until challenge. While all naive control macaques showed acute CD4
+
T-cell depletion at week 2 after an intravenous SHIV89.6PD challenge, all the macaques vaccinated with the prime/boost regimen were protected from depletion and showed greatly reduced peak viral loads compared with controls. Vaccination with the DNA alone or SeV-Gag alone was not enough to confer the consistent protection from the depletion, although it led to efficient secondary CD8
+
T-cell responses at week 2 after challenge. At week 1, a difference in the secondary responses between the protected and the unprotected macaques was clear; rapid augmentation of virus-specific CD8
+
T cells was detected in the former but not in the latter. Thus, our results indicate the importance of rapid secondary responses for reduction in the peak viral loads and protection from acute CD4
+
T-cell depletion.
Intracellular Signaling Molecules Activated by Epstein-Barr Virus for Induction of Interferon Regulatory Factor 7
Authors: Zhang Luwen , Wu Lihong , Hong Ke , Pagano Joseph S.
Published: July 2002

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP-1) is the principal oncogenic protein in the EBV transformation process. LMP-1 induces the expression of interferon regulatory factor 7 (IRF-7) and activates IRF-7 protein by phosphorylation and nuclear translocation. LMP-1 is an integral membrane protein with two regions in its C terminus that initiate signaling processes, the C-terminal activator regions 1 (CTAR-1) and CTAR-2. Here, genetic analysis of LMP-1 has determined that the PXQXT motif that governs the interaction between LMP-1 CTAR-1 and tumor necrosis factor receptor-associated factors (TRAFs) is needed to induce the expression of IRF-7. Mutations in the PXQXT motif in CTAR-1 that disrupt the interaction between LMP-1 and TRAFs abolished the induction of IRF-7. Also, dominant-negative mutants of TRAFs inhibited the induction of IRF-7 by CTAR-1. The last three amino acids (YYD) of CTAR-2 are also important for the induction of IRF-7. When both PXQXT and YYD were mutated (LMP-DM), the LMP-1 mutant failed to induce IRF-7. Also, LMP-DM blocked the induction of IRF-7 by wild-type LMP-1. These data strongly suggest that both CTAR-1 and CTAR-2 of LMP-1 independently induce the expression of IRF-7. In addition, NF-κB is involved in the induction of IRF-7. A superrepressor of IκB (sr-IκB) could block the induction of IRF-7 by LMP-1, and overexpression of NF-κB (p65 plus p50) could induce the expression of IRF-7. In addition, we have found that human IRF-7 is a stable protein, and sodium butyrate, a modifier of chromatin structure, induces IRF-7.
Persistence of Pathogenic Challenge Virus in Macaques Protected by Simian Immunodeficiency Virus SIVmacΔ
nef
Authors: Khatissian Emmanuel , Monceaux Valérie , Cumont Marie-Christine , Kieny Marie-Paule , Aubertin Anne-Marie , Hurtrel Bruno
Published: July 2002

Live attenuated simian immunodeficiency virus (SIV) is the most efficient vaccine yet developed in monkey models of human immunodeficiency virus infection. In all successful vaccine trials, attenuation was achieved by inactivating at least the
nef
gene. We investigated some virological and immunological characteristics of five rhesus macaques immunized with a
nef
-inactivated SIVmac251 molecular clone (SIVmac251Δ
nef
) and challenged 15 months later with the pathogenic SIVmac251 isolate. Three animals were killed 2 weeks postchallenge (p.c.) to search for the challenge virus and to assess immunological changes in various organs. The other two animals have been monitored up for 7 years p.c., with clinical and
nef
gene changes being noted. The animals killed showed no increase in viral load and no sign of a secondary immune response, although the challenged virus was occasionally detected by PCR. In one of the monkeys being monitored, the vaccine virus persisted and an additional deletion occured in
nef
. In the other monkey that was monitored, the challenge and the vaccine (Δ
nef
) viruses were both detected by PCR until a virus with a hybrid
nef
allele was isolated 48 months p.c. This
nef
hybrid encodes a 245-amino-acid protein. Thus, our results show (i) that monkeys were not totally protected against homologous virus challenge but controlled the challenge very efficiently in the absence of a secondary immune response, and (ii) that the challenge and vaccine viruses may persist in a replication-competent form for long periods after the challenge, possibly resulting in recombination between the two viruses.
Kaposi's Sarcoma-Associated Herpesvirus Can Productively Infect Primary Human Keratinocytes and Alter Their Growth Properties
Authors: Cerimele Francesca , Curreli Francesca , Ely Scott , Friedman-Kien Alvin E. , Cesarman Ethel , Flore Ornella
Published: July 2002

Previous studies have shown the presence of Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) DNA in endothelial cells, in keratinocytes in the basal layer of the epidermis overlying plaque-stage nodular lesions of cutaneous Kaposi's sarcoma (KS), and in the epithelial cells of eccrine glands within KS lesions. We infected primary cell cultures of human keratinocytes with KSHV/HHV8. At 6 days post infection, transcription of viral genes was detected by reverse transcriptase PCR (RT-PCR), and protein expression was documented by an immunofluorescence assay with an anti-LANA monoclonal antibody. To determine whether the viral lytic cycle was inducible by chemical treatment, KSHV/HHV8-infected keratinocytes were treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) and RT-PCR was performed to confirm the transcription of lytic genes such as open reading frame 26, (which encodes a capsid protein). Finally, to assess infectious viral production, other primary human cells (human umbilical vein endothelial cells), were infected with concentrated supernatant of KSHV-infected, TPA-induced keratinocytes and the presence of viral transcripts was confirmed by RT-PCR. The uninfected keratinocytes senesced 3 to 5 weeks after mock infection, while the KSHV/HHV8-infected keratinocytes continued to proliferate and to date are still in culture. However, 8 weeks after infection, viral genomes were no longer detectable by nested PCR. Although the previously KSHV/HHV8-infected keratinocytes still expressed epithelial markers, they acquired new characteristics such as contact inhibition loss, telomerase activity, anchorage-independent growth, and changes in cytokine production. These results show that KSHV/HHV8, like other herpesviruses, can infect and replicate in epithelial cells in vitro and suggest that in vivo these cells may play a significant role in the establishment of KSHV/HHV8 infection and viral transmission.
Reassortment In Vivo: Driving Force for Diversity of Human Rotavirus Strains Isolated in the United Kingdom between 1995 and 1999
Authors: Iturriza-Gómara Miren , Isherwood Beverley , Desselberger Ulrich , Gray Jim
Published: July 2002

The G and P genotypes of 3,601 rotavirus strains collected in the United Kingdom between 1995 and 1999 were determined (M. Iturriza-Gómara et al., J. Clin. Microbiol. 38:4394–4401, 2000). In 95.4% of the strains the most common G and P combinations, G1P[8], G2P[4], G3P[8], and G4P[8], were found. A small but significant number (2%) of isolates from the remaining strains were reassortants of the most common cocirculating strains, e.g., G1P[4] and G2P[8]. Rotavirus G9P[6] and G9P[8] strains, which constituted 2.7% of all viruses, were genetically closely related in their G components, but the P components of the G9P[8] strains were very closely related to those of cocirculating strains of the more common G types (G1, G3, and G4). In conclusion, genetic interaction by reassortment among cocirculating rotaviruses is not a rare event and contributes significantly to their overall diversity.
Temperature Dependence of Viscosity B-Coefficients of Aqueous Solutions of Chlorides of Na+, K+, Mg2+, Ca2+, Ba2+, Sr2+, Co2+, Ni2+, Cu2+ and Cr3+
Authors: Afzal Muhammad , Iqbal Muhammad J. , Ahmad Habib
Published: July 2002

The viscosity B-coefficients of the aqueous chlorides of Na+, K+, Mg2+, Ca2+, Ba2+, Sr2+, Co2+, Ni2+, Cu2+ and Cr3+ have been calculated from the parameters of an empirical equation of the form η = a0 exp(b0cM + d0cM2) and were found to be comparable with literature values. The variation of B-values with temperature between 20 - 50 °C has been described in terms of structure making/breaking behaviour of the cations.
Pyridinium Ions - New Probe for Basic Sites of Solid Acids
Authors: Kotrla Josef , Florián Jan , Kubelková Ludmila , Fraissard Jacques
Published: July 2002

The hydrogen bonding interactions of the pyridinium ion (PyH+) with the deprotonated skeleton of acid zeolites were studied using Fourier transform infrared (FTIR) spectroscopy and quantum chemical ab initio calculations. It was found that the frequency of the NH stretching vibration, n(NH), of the newly formed H-bond increases in the zeolite sequence HNaX < HY < HM ~ HZSM-5. This is related to decreasing basicity of the skeletal oxygens (basic sites conjugated to bridging hydroxyls). Therefore, pyridine can serve as a probe for the basic sites of acid zeolites. In this way it can complement the pyrrole probe, which is established for basicity monitoring of alkali-metal exchanged zeolites.
Condensation Reactions of 1,2,3,4-Tetrahydro-6-methyl-2,4-dioxo-5-pyrimidinecarbaldehyde
Authors: Bobáľ Pavel , Gažo Roman , Kada Rudolf , Ilavský Dušan , Prónayová Naďa , Zalibera Lubomír
Published: July 2002

Condensation reactions of 1,2,3,4-tetrahydro-6-methyl-2,4-dioxo-5-pyrimidinecarbaldehyde with nine acid derivatives containing an active methylene group are described. The obtained products were characterized by their IR, UV, 1H NMR, 13C NMR and mass spectra. The stereochemistry of selected products was studied by 1H and 13C NMR spectroscopy.
Effects of Medium and Substituents on Dissociationof 4,4'-Disubstituted Bis(benzenesulfon)imides
Authors: Ludwig Miroslav , Štverka Pavel
Published: July 2002

Ten 4,4'-disubstituted bis(arenesulfon)imides of the general formula XC6H4SO2NHSO2C6H4X have been synthesized and their structures confirmed by their 1H NMR spectra. Elemental analyses are presented for the compounds not yet described. The dissociation constants of these model substances have been measured potentiometrically in pyridine, dimethylformamide, methanol, ethanol, propylene carbonate, acetone, acetonitrile, 1,2-dichloroethane and tetramethylene sulfone. The pKHA values obtained have been correlated with three sets of the Hammett substituent constants and the results have been used to discuss the solvent and substituent effects on the dissociation of the compounds studied. Sulfonimides with electron-acceptor substituents behave as rather strong acids in some solvents (pyridine, dimethylformamide, methanol and ethanol), whereas normal substituent dependences are found in other solvents. The experimental data have also been interpreted with the help of the statistical methods based on latent variables. From the calculations it follows that only the first principal component, which correlates well with the substituent constant sets adopted, is statistically significant in describing the substituent effect on the acid-base process studied.
A Specific π-Ligand Transfer Reaction via Triple-Decker Sandwich Complex Intermediates
Authors: Böhm Dieter , Heinemann Frank , Hu Dongqi , Kummer Susanne , Zenneck Ulrich
Published: July 2002

Photochemically generated cationic cyclopentadienyl iron fragments [FeCp]+ allow a specific stacking reaction of [(t-Bu3C3P2)Fe(t-Bu2C2P3)]. This results in the transient formation of an unstable cationic Fe-Fe triple-decker sandwich complex which decomposes by deliberating the neutral sandwich complex [CpFe(t-Bu2C2P3)], and is stacked again by a second [FeCp]+-unit, yielding the moderately stable cationic triple-decker sandwich complex [CpFe(t-Bu2C2P3)FeCp]+ with a central mi-eta5:eta5-triphospholyl ligand. Air exposure or storage of solutions at room temperature leads to a destacking and the neutral triphosphaferrocene derivative [CpFe(t-Bu2C2P3)] is formed again almost quantitatively in respect to the pentaphospha-ferrocene educt.
Phase Stability of Hydrogen-Bonded Polymer Mixtures. III. Spinodal Diagrams
Authors: Pouchlý Julius , Živný Antonín , Sikora Antonín
Published: July 2002

Relations derived on the basis of the Barker-Guggenheim quasichemical theory were used for construction of spinodal diagrams (temperature versus composition) of a mixture of two polymers in which hydrogen bonds and other strong interactions exist. A function dependence of parameters of quasichemical equilibrium, η, was proposed, which has the form of the Boltzmann function at lower temperatures, but at higher temperatures corresponds to random mixing. The spinodal diagrams were constructed for several sets of dependences of η on temperature in a wide temperature range for different chain lengths, r, or for different values of the content of polar groups in one of the polymers. According to circumstances, the phase diagram shows one or two temperature regions of phase instability or the phase instability occurs in a certain range of composition at any temperature. Though the chain length was chosen equal for both polymers, the phase diagrams are asymmetric in the sense that the critical points are shifted towards that border of the diagram which corresponds to the component with a larger relative content of the polar group. The temperature range of phase instability is strongly influenced by small changes in the relative surface area of polar groups in the molecules.
Agroclavine Glycosylation
Authors: Křen Vladimír , Halada Petr , Sedmera Petr
Published: July 2002

Agroclavine was converted into its 1-hydroxymethyl derivative by condensation with formaldehyde and enzymatically glycosylated using β-galactosidase from Aspergillus oryzae.
Photoelectromotive Force (PEMF) Studies of [Fe(CN)5SCN]3- Complex Ions Adsorbed on Pb(SCN)2 Semiconductor Surfaces
Authors: Hennig Horst , Kokorakis Athanasios , Fränzle Stefan , Damm Cornelia , Müller Franz W. , Israel Gunter
Published: July 2002

Adsorbates of [Fe(CN)5SCN]3- complex ions on semiconducting Pb(SCN)2 surfaces were subject to photoelectromotive force (PEMF) investigations. Laser flash excitation of the adsorbates at 560 nm yields a weak PEMF signal due to spectral sensitization of the semiconductor Pb(SCN)2, not absorbing in the visible region. PEMF signals observed with laser flash excitation at 337 nm are explained by hole trapping accompanied with photoinduced redox reactions of the complex, when the number of flashes is increased.
(9H-Fluoren-9-ylidene)fluoromethyllithium, a Stabilized Fluoroalkenyl Carbanion. Preparation, Reactions, 13C and 19F NMR Spectra
Authors: Kvíčala Jaroslav , Pelter Andrew
Published: July 2002

(9H-Fluoren-9-ylidene)fluoromethyllithium (1) was prepared by a low-temperature transmetallation of bromo(9H-fluoren-9-ylidene)fluoromethane (2). Whereas the synthesis of unlabeled bromofluoroalkene 2a was based on Wittig-Horner reaction of fluorenone (3) with ethyl (diethoxyphosphoryl)fluoroacetate (4), (1-13C)-labeled compound 2b was obtained via an addition of labeled lithium 1-ethoxy-2-fluoro(2-13C)ethen-1-olate (5) to ketone 3. Fluoroethenyllithium 1 was found by a low-temperature 19F NMR spectroscopy to be stable up to -40 °C; it was reacted with the series of electrophiles, e.g. benzaldehyde (6), methyl iodide (7) or chloro(trimethyl)silane (8). 13C NMR experiments with (1-13C)-labeled 1a proved that fluorocarbenoid 1 is probably monomeric in THF solution in analogy to other halocarbenoids.
Drug related medical emergencies in the elderly: role of adverse drug reactions and non-compliance
Authors: Malhotra S , Karan R S , Pandhi P , Jain S
Published: July 2002

BACKGROUND

Adverse drug reactions and non-compliance are important causes of admissions in the elderly to medical clinics. The contribution of adverse drug reactions and non-compliance to admission by the medical emergency department was analysed.

METHODS

A total of 578 consecutive elderly patients admitted to the medical emergency department were interviewed to determine the percentage of admissions due to adverse drug reactions or non-compliance with medication regimens, their causes, consequences, and predictors.

Results

Eighty three (14.4%) of the 578 admissions were drug related: 39 (6.7%) caused by adverse drug reactions and 44 (7.6%) caused by non-compliance with medication. One hundred ninety two (33.2%) patients had a history of non-compliance. Factors associated with an increased risk of admission because of an adverse drug reaction were patients with diabetes or neoplasms, and patients using numerous different medications. Factors associated with a higher risk of hospitalisation because of non-compliance were poor recall of the medication regimen, seeing numerous physicians, female sex, polypharmacy, drug costs, and switching over to non-conventional forms of treatment.

Conclusion

Many elderly admissions are drug related, with non-compliance accounting for a substantial fraction of these. Elderly people at high risk of suffering a drug related medical emergency are identified and suitable interventions may be planned by the healthcare policymakers to target them.
Validation of seismic design parameters for wood-frame shearwall systems
Authors: Ceccotti Ario , Karacabeyli Erol
Published: July 2002

A methodology for assessment of seismic design parameters for a wood-frame shearwall system is developed, consisting of a test program of shearwalls and the application of nonlinear time history analyses to a four-storey wood-frame building that was designed to resist the seismic requirements for Vancouver, British Columbia. Analyses employed 22 selected earthquake accelerograms that were scaled upwards until an ultimate peak ground acceleration (Au) was reached where the shearwall reached a "near-collapse" state. The 22 values of Au were found to be greater than the "design" peak ground acceleration, indicating the adequacy of the current design procedures for the particular shearwalls investigated. The influence of gypsum wallboard on the behaviour of the shearwalls was also evaluated, and a new force modification factor "R" for walls composed of a mixture of wood-based and gypsum panels was proposed. The effect of flexibility of floor diaphragms was considered separately for a symmetric building and was found to have 5-30% reduction on the Au values obtained for the rigid diaphragm case.Key words: seismic design, earthquake loads, timber structures, wood shearwalls.
Improvements of electroosmotic consolidation of soft clays by minimizing power loss at electrodes
Authors: Lefebvre Guy , Burnotte Fabien
Published: July 2002

Although it appears promising in many laboratory studies, electroosmotic consolidation of soft clays is seldom used in practical applications. A study of well-documented case records of field applications illustrates the difficulty of transmitting the electrical potential to the soil deposit through the use of electrodes. An important amount of the electrical potential is indeed lost at the soilelectrode contact. The loss of potential at this point has been studied in a laboratory setup designed to reproduce the conditions existing in the field during electroosmotic consolidation. The laboratory results confirm that only about a third of the electrical potential applied at the electrodes is effectively transmitted to the soil and available for electroosmotic consolidation. Moreover, the laboratory studies have shown that a chemical treatment to increase the soil conductivity at the soilelectrode contact can double the electrical potential effectively transmitted to the soil and greatly improve the performance of electroosmotic consolidation.Key words: electroosmosis, soft clays, consolidation, potential loss, electrode treatment, soil improvement.
FINDING SMALLEST SUPERTREES UNDER MINOR CONTAINMENT
Authors: NISHIMURA NAOMI , RAGDE PRABHAKAR , THILIKOS DIMITRIOS M
Published: July 2002

The diversity of application areas relying on tree-structured data results in wide interest in algorithms which determine differences or similarities among trees. One way of measuring the similarity between trees is to find the smallest common superstructure or supertree, where common elements are typically defined in terms of a mapping or embedding. In the simplest case, a supertree will contain exact copies of each input tree, so that for each input tree, each vertex of a tree can be mapped to a vertex in the supertree such that each edge maps to the corresponding edge. More general mappings allow for the extraction of more subtle common elements captured by looser definitions of similarity.

We consider supertrees under the general mapping of minor containment. Minor containment generalizes both subgraph isomorphism and topological embedding; as a consequence of this generality, however, it is NP-complete to determine whether or not G is a minor of H, even for genreal trees. By focusing on trees of bounded degree, we obtain an O(n3) algorithm which determines the smallest tree T such that both of the input trees are minors of T, even when the trees are assumed to be unrooted and unordered.
A CHARACTERIZATION OF k-TH POWERS Pn,k OF PATHS IN TERMS OF k-TREES
Authors: Yamazaki Koich , Tani Sei'ichi , Nishino Tetsuro
Published: July 2002

Let G be a k-tree such that |{v ∈ V(G): degG(v) = k}| = 2, n = |V(G)| ≥ 2k + 2, and the maximum degree of G is at most 2k. In this paper, we will show that such a k-tree G is isomorphic to Pn,k. In this way, we give a new characterization of k-th power (i.e. Pn,k) of paths with n vertices in terms of k-trees.
AF FLOWS AND CONTINUOUS SYMMETRIES
Authors: BRATTELI O. , KISHIMOTO A.
Published: July 2002

We consider AF flows, i.e. one-parameter automorphism groups of a unital simple AF C*-algebra which leave invariant the dense union of an increasing sequence of finite-dimensional *-subalgebras, and derive two properties for these; an absence of continuous symmetry breaking and a kind of real rank zero property for the almost fixed points.
COVARIANT QED WITHOUT INDEFINITE METRIC
Authors: THIRRING W. , NARNHOFER N.
Published: July 2002

We construct for the linearized Higgs model a representation of the field operators in a Hilbert space ℋ with the following features:

ℋ has a positive definite metric but is nonseparable.

The vacuum is gauge invariant.

The gauge variant operators exist only in their exponentiated form as unitaries.

There is a subspace of ℋ where [Formula: see text] is represented by 0.
HILBERT SPACE REPRESENTATIONS OF THE GAUGE GROUPS OF SOME TWO DIMENSIONAL FIELD THEORIES
Authors: CAREY A. L. , WRIGHT J. D.
Published: July 2002

In this paper we show how the representation theory of gauge groups developed in [7] and [8] to study the massless Thirring model and representations of affine Lie algebras may be applied to the Schwinger model and to diagonal QCD 2. We also discusss how this sheds light on the currently unsolved problem of QCD 2 itself. We show how to construct operators which approximate the quantum fields of the respective models on Hilbert space, how to represent the local gauge groups by unitary operators, positivity of the n-point functions in a definite metric quantisation and how to determine the observables and vacuum structure. This analysis counterpoints the related work in [17] on the indefinite metric version of the Schwinger model.
TENSOR PRODUCT DECOMPOSITIONS FOR AFFINE KAC-MOODY ALGEBRAS
Authors: GOULD M. D.
Published: July 2002

The decomposition into irreducible modules is determined, for the tensor product of two arbitrary irreducible integrable highest weight modules, for an (untwisted) affine Kac-Moody algebra L. The result is applied to investigate full multiplicity regions and cyclic modules within the tensor product space for an affine Kac-Moody algebra. The tensor product decomposition into irreducible modules over L ⊕ Vir (Coset construction), Vir the Virasoro algebra, is also briefly investigated.
INFINITE, σ-FINITE, NON-W*, AW*-FACTORS
Authors: HAMANA MASAMICHI
Published: July 2002

Given any infinite cardinal κ and a κ-dimensional Hilbert space H, the set of all non-W*, AW*-factors, which can be completely isometrically embedded in B(H), is proved to have cardinality 22κ.
THE HAMMING ASSOCIATIVE MEMORY REVISITED
Authors: ANDRECUT M. , ALI M. K.
Published: July 2002

Here, we review the classical Hamming associative memory and we discuss a cellular implementation. We show how the patterns to be stored can be superimposed or enfolded onto a single memory element with exponential storage capacity and how these memory elements can be organized in a cellular network architecture suitable for pattern association.
(2+1)-AdS GRAVITY ON RIEMANN SURFACES
Authors: VALTANCOLI P.
Published: July 2002

We discuss a formalism for solving (2+1)-AdS gravity on Riemann surfaces. In the torus case the equations of motion are solved by two functions f and g, solutions of two independent O(2,1) sigma models, which are distinct because their first integrals contain a different time dependent phase factor. We then show that with the gauge choice [Formula: see text] the same couple of first integrals indeed solves exactly the Einstein equations for every Riemann surface. The XA= XA(xμ) polydromic mapping which extends the standard immersion of a constant curvature three-dimensional surface in a flat four-dimensional space to the case of external point sources or topology, is calculable with a simple algebraic formula in terms only of the two sigma model solutions f and g. A trivial time translation of this formalism allows us to introduce a new method which is suitable to study the scattering of black holes in (2+1)-AdS gravity.
AdS/CFT DUALITY AND CONFORMALITY FOR NON-ABELIAN ORBIFOLD
Authors: FRAMPTON PAUL H.
Published: July 2002

An outline of conformality approach to the gauge hierarchy is given including the use of non-abelian orbifolds to give unified model of the left-right type.
NOTE ON A POSITRONIUM MODEL FROM FLOW EQUATIONS IN FRONT-FORM DYNAMICS
Authors: TRITTMANN UWE
Published: July 2002

In this note we address the problem of solving for the positronium mass spectrum. We use front-form dynamics together with the method of flow equations. For a special choice of the similarity function, the calculations can be simplified by analytically integrating over the azimuthal angle. One obtains an effective Hamiltonian and we solve numerically for its spectrum. Comparing our results with different approaches we find encouraging properties concerning the cutoff dependence of the results.
MESOSCOPIC TRANSPORT THROUGH A QUANTUM-DOT-EMBEDDED AHARONOV–BOHM RING THREADED WITH AC FLUX
Authors: ZHAO HONG-KANG
Published: July 2002

The electron transporting through a mesoscopic ring embedded with one quantum dot and threaded by dc and ac magnetic fluxes is investigated by employing the Keldysh nonequilibrium Green function technique. The tunneling current and differential conductance are derived to show the Aharonov–Bohm-like effect induced by external magnetic fluxes. The multi-channel ring and multi-level quantum dot system is studied. The quenching and nonmonotone effects versus the magnitude of ac flux are revealed in differential conductance. This signifies that at some values of ac flux, the tunneling current may be suppressed or enhanced. The differential conductance oscillation and I-V characteristics are studied numerically at zero temperature. The aperiodically nonmonotonical conductance versus the magnitude of ac flux, multi-channel negative differential conductance, photon-electron pump effect are also observed.
NEW PERSPECTIVES IN THE APPLICATION OF THE DIFFUSION MONTE CARLO METHOD TO THE STUDY OF LIQUID 3He
Authors: BORONAT J. , CASULLERAS J.
Published: July 2002

With the standard techniques to deal with the sign problem in a diffusion Monte Carlo (DMC) calculation, i.e., fixed node (FN) and released node (RN), we have re-explored the application of DMC to the study of normal liquid 3 He at zero temperature. Our analysis points to the necessity of including optimized backflow correlations to quantitatively improve the FN-DMC results. The theoretical equation of state so obtained fits the experimental data for the energy, the pressure and the sound velocity. The upper bounds provided by the FN method are checked on the one hand by the application of RN, and on the other, by the inclusion of explicit three-body correlations in the backflow operator. Both calculations show negligible corrections with respect to the characteristic size of the statistical error.
ENERGY TRANSFER IN THE PERIDININ CHLOROPHYLL a PROTEIN OF AMPHIDINIUM CARTERAE STUDIED BY POLARIZED ABSORPTION MEASUREMENTS
Authors: LAMPOURA STEFANIA. S. , KRUEGER B. P. , VAN STOKKUM I. H. M. , SALVERDA J. M. , GRADINARU C. C. , RUTKAUSKAS D. , HILLER R. G. , VAN GRONDELLE R.
Published: July 2002

In this work we report the results of ultrafast transient absorption studies which examined energy transfer between carotenoids and chlorophylls in Peridinin-Chlorophyll-a-Protein (PCP) light harvesting complex from the dinoflagellate Amphidinium carterae. Global analysis of the isotropic decay reveals that the peridinin lifetime in PCP is 2.3±0.2 ps. This time constant is the peridinin- Chl a energy transfer, which is essentially entirely mediated by coupling of the peridinin S 1 and Chl a Q y transitions. Based on this lifetime we estimated an energy transfer timescale of ~2.4 ps and a peridinin- Chl a coupling of 46 cm -1. The magnitude of this coupling suggests a peridinin S 1 transition dipole moment of ~3 D . Global analysis of the depolarization measurements, shows, a small decrease in the depolarization from the initial 0.4 value to 0.36±0.03. This decrease occurs on the same timescale as the S2→S1 internal conversion, suggesting that either the S 1 transition dipole is oriented ~15° away from the S 2 transition dipole, or, that a small amount of peridinin S 2-peridinin S 2 energy transfer occurs in competition with internal conversion, or some combination of the two.
PHOTOPHYSICAL OVERVIEW OF EXCITATION ENERGY TRANSFER IN ORGANIC MOLECULAR ASSEMBLIES — A ROUTE TO STUDY BIO-MOLECULAR ARRAYS —
Authors: MATSUI A. H. , TAKESHIMA M. , MIZUNO K. , AOKI-MATSUMOTO T.
Published: July 2002

Excitonic processes in organic molecular crystals are discussed in terms of two parameters, the crystal size and the constituent molecule size. From the luminescence and absorption spectra of a series of aromatic molecular crystals we find a systematic change in exciton energy transport as functions of the size of crystal and its constituent molecule size. Characteristic features of bulk crystals and microcrystallites are as follows. (1) In bulk crystals exciton energy transport depends on the constituent molecule size. When molecules are small, the exciton energy transport occurs by free excitons, but when molecules are large free exciton transport disappears because excitons get self-trapped. (2) In microcrystallites, exciton energy transport depends on the crystallite size. When the size is larger than a critical one, excitons travel as quantum mechanical waves but when the size is smaller than the critical one the exciton waves get confined within the crystallite. The results are independent of the chemical species of constituent molecules and thus applicable to novel molecular arrays such as biological molecular arrays.
FORMATION OF SEMI-COHERENT INTERFACE IN TiSi2/Si STRUCTURE
Authors: LI S. , ZHANG L. , LIANG M. H. , SUN C. Q. , WIDJAJA S. , LEE Y. K.
Published: July 2002

The interfacial characteristics of the TiSi 2/ Si structure were investigated in detail. It was found that the semi-coherent formed with a certain disregistry which was periodically taken up by the misfit dislocations between every three (030)C49 planes. The semi-coherent interface dominated the interfacial structure in the material and was responsible to the wavy surface of TiSi 2/ Si structure. However, the interface accommodated higher energy was a favorable nucleation sites for the C54 phase. Its existence may enhance the C54 phase formation in the further thermal treatments.
MANY-BODY EFFECTS IN FRICTIONAL DRAG BETWEEN COUPLED TWO-DIMENSIONAL ELECTRON SYSTEMS
Authors: HU BEN YU-KUANG
Published: July 2002

Independently contacted coupled quantum wells separated by barriers which allow significant interlayer interactions but no tunneling have been fabricated. When current is passed through one layer, the interlayer interactions drag carriers in the second layer, resulting in a voltage response (for open circuits). The magnitude of the response gives a quantitative measure of the effective interlayer interactions and response functions of the system, and hence this is an excellent laboratory for the study of many-body phenomena in two-dimensional electron gases. We review the Boltzmann and Kubo formalisms for the theory of drag effects in coupled quantum wells and discuss three specific cases where many-body effects significantly affect the drag: (1) acoustic phonon-mediated drag, (2) large enhancements due to coupled plasmon modes, and (3) interplay of screening and Landau levels in large magnetic fields.
DX CENTERS IN AlGaN
Authors: McCLUSKEY M. D. , VAN de WALLE C. G. , JOHNSON N. M. , BOUR D. P. , KNEISSL M.
Published: July 2002

In this letter, recent theoretical and experimental investigations of DX centers in Al x Ga 1-x N are reviewed. Due to the technological importance of III–V nitride semiconductors, studies of deep-level defects in AlGaN have attracted a great deal of interest. Oxygen impurities form DX centers in GaN under hydrostatic pressure and in Al x Ga 1-x N alloys. For GaN under pressures greater than 20 GPa, the DX level emerges from the conduction band, leading to a decrease in the free-electron concentration. The localization of free carriers leads to a decrease in the far-infrared absorption and an increase in the LO Raman peak intensity. In Al x Ga 1-x N alloys, Hall effect and persistent photoconductivity measurements indicate that the DX state is energetically favorable for x>0.3. The experimental data for oxygen DX centers are in excellent agreement with first-principles calculations. Experiments have shown that silicon remains a shallow donor up to at least x=0.5 and theory indicates that it may remain shallow up to x=1.
CRITICAL CURRENT DEPENDENCE ON AXIAL STRAIN AT LN2 TEMPERATURE OF AG-CLAD BI(2223) TAPES
Authors: MAYO BEN DE
Published: July 2002

The critical currents (1 μvolt/cm criterion) or commercially supplied tapes of Bi2Sr2Ca2Cu3OX (Bi(2223)) in Ag were measured at LN2 temperature as axial stresses of up to 220 MPa were applied. The critical current decreased linearly with increasing strain up to the point or plastic deformation, whereupon it dropped discontinuously to less than 10% or the unstressed value. The resistivity of a pure silver sample was also tested at LN2 temperature it was constant with increasing stress up to (the same) point of plastic deformation; then it increased linearly. Youngs modulus and the yield strength at LN2 and room temperature are compared.
LOCAL STRUCTURE CHARACTERIZATION OF GADOLINIUM DOPED AMORPHOUS AND CRYSTALLINE ALUMINA
Authors: SIMON S.
Published: July 2002

The evolution of local structure during the transition from amorphous to crystalline states of gadolinium doped alumina is characterized by electron paramagnetic resonance (EPR). The EPR spectra of samples belonging to the (1 - x) Al 2 O 3x Gd 2 O 3 system, where x = 0.002, 0.01, 0.05 and 0.1, show that the gadolinium ions are relatively uniformly distributed in amorphous alumina granules prepared by sol–gel methods. First, gadolinium doped α-alumina appears on the surface of the γ-alumina granules where there are low coordinated (N < 6) gadolinium species. The transition from γ- to α-alumina is postponed by the presence of high coordinated gadolinium (N < 6) ions inside of γ-alumina granules.
ANGULAR MOMENTUM-PHASE WIGNER OPERATOR FOR DESCRIBING ELECTRONS IN UNIFORM MAGNETIC FIELDS
Authors: FAN HONGYI
Published: July 2002

By introducing the angular momentum-phase Wigner operator both in <λ| representation and <l,r| representation, which are respectively the eigenstates of position and angular momentum of an electron in a uniform magnetic field, we establish the angular momentum-phase Wigner function whose marginal distributions are physically meaningful.
RECOMBINATION PARAMETERS OF CdxI1-xSe EPITAXIAL LAYERS FROM THE PHOTOCONDUCTIVE EFFECT
Authors: CERBANIC GEORGETA , BURDA IOAN , SIMON SIMION
Published: July 2002

The study of lifetimes regarding the recombination of non-equilibrium carriers and their kinetics is essential in order to explain the recombination mechanisms in semiconductors. The study of recombination kinetics and lifetime values in CdSe epitaxial layers is the target of this paper. CdSe layers have been deposited on (0001) mica substrates by vapor epitaxial method. The epitaxial layers contain defects that induce gap states and specific recombination kinetics. The lifetimes were determined by photoconductive frequency-resolved spectroscopy (PCFRS), a usual method for such measurements. The lifetime spectra obtained show in all studied samples the presence of three types of recombinations: τ1 is due to band-to-band recombination, τ2 to surface recombination associated with chemical impurities and τ3 to surface recombination associated with structural defects. The lifetime measured as a function of the substrate temperature denotes a complex correlation between the crystal perfection and the growth temperature.
STRING PICTURE OF BOSE–EINSTEIN CONDENSATION
Authors: BUND S. , SCHAKEL A. M. J.
Published: July 2002

A nonrelativistic Bose gas is represented as a grand-canonical ensemble of fluctuating closed spacetime strings of arbitrary shape and length. The loops are characterized by their string tension and the number of times they wind around the imaginary time axis. At the temperature where Bose–Einstein condensation sets in, the string tension, being determined by the chemical potential, vanishes and the strings proliferate. A comparison with Feynman's description in terms of rings of cyclicly permuted bosons shows that the winding number of a loop corresponds to the number of particles contained in a ring.
MINIMUM UNCERTAINTY RELATION FOR CORRELATED ELECTRON STATE OF COOPER PAIR
Authors: FAN HONG-YI , LIN JING-XIAN
Published: July 2002

We point out that the BCS ground state of correlated electrons makes the uncertainty relation [Formula: see text] reach its minimum value, where [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] denote Cooper pair annihilation and creation operators, [Formula: see text] and z3 obey a closed pseudospin SU(2) Lie algebra. So, the BCS state is the state most approaching the "classical" situation.
SELF-ORGANIZATION AND NONLINEAR DYNAMICS OF NUCLEIC ACID–WATER SYSTEM
Authors: TOLSTORUKOV M. YE. , GATASH S. V.
Published: July 2002

We proceed our research on the physical modeling of the conformational transitions in the nucleic acid molecule during the water desorption–resorption cycle. The nucleic acid-water system is considered as an open system and simulated with a trigger model. The analysis of kinetic equations and the analysis based on the nonlinear master equations show the nontrivial bifurcation behavior of the system which leads to the multistability. This fact allows one to explain the hysteresis phenomena observed experimentally in the nucleic acid–water system by the presence of the metastable states. Besides, autowave processes, such as traveling fronts of a new conformation (trigger waves), oscillations are possible in the corresponding distributed parameter system, if the diffusion of the water molecules is taken into account. The problem of self-organization in the nucleic acid–water system is of great importance for revealing physical mechanisms of the functioning of nucleic acids and for many specific practical fields.
ORGANISATIONAL RULES AS AN ABSTRACTION FOR THE ANALYSIS AND DESIGN OF MULTI-AGENT SYSTEMS
Authors: ZAMBONELLI FRANCO , JENNINGS NICHOLAS R. , WOOLDRIDGE MICHAEL
Published: July 2002

Multi-agent systems can very naturally be viewed as computational organisations. For this reason, we believe organisational abstractions offer a promising set of metaphors and models that can be exploited in the analysis and design of such systems. To this end, the concept of role models is increasingly being used to specify and design multi-agent systems. However, this is not the full picture. In this paper we introduce three additional organisational concepts — organisational rules, organisational structures, and organisational patterns — and discuss why we believe they are necessary for the complete specification of computational organisations. In particular, we focus on the concept of organisational rules and introduce a formalism, based on temporal logic, to specify them. This formalism is then used to drive the definition of the organisational structure and the identification of the organisational patterns. Finally, the paper sketches some guidelines for a methodology for agent-oriented systems based on our expanded set of organisational abstractions.
AUTOMATIC CONVERSION FROM FIBONACCI REPRESENTATION TO REPRESENTATION IN BASE φ, AND A GENERALIZATION
Authors: FROUGNY CHRISTIANE , SAKAROVITCH JACQUES
Published: July 2002

Every positive integer can be written as a sum of Fibonacci numbers; it can also be written as a (finite) sum of (positive and negative) powers of the golden mean φ. We show that there exists a letter-to-letter finite two-tape automaton that maps the Fibonacci representation of any positive integer onto its φ-expansion, provided the latter is folded around the radix point. As a corollary, the set of φ-expansions of the positive integers is a linear context-free language. These results are actually proved in the more general case of quadratic Pisot units.

Résumé: Tout nombre entier positif peut s'écrire comme une somme de nombres de Fibonacci; tout entier peut également s'écrire comme une somme (finie) de puissances (positives et négatives) du "nombre d'or" φ. Nous montrons qu'il existe un automate à deux bandes, fini et lettre-à-lettre, qui envoie la représentation d'un entier en base de Fibonacci sur sa représentation dans la base φ modulo le fait qu'on a replié cette dernière autour du point décimal. On en déduit que l'ensemble des représentations des entiers en base φ est un langage context-free linéaire. Tous ces résultats sont en fait établis dans le cas général où la base considérée est un nombre de Pisot quadratique unitaire.
A SURGERY DESCRIPTION OF AN INTEGRAL HOMOLOGY THREE-SPHERE RESPECTING THE CASSON INVARIANT
Authors: ISHIWATA MAKIKO
Published: July 2002

In 1998, C. Lescop proved that any integral homology sphere with the Casson invariant zero can be obtained from S3 by surgery on a boundary link each component of which has a trivial Alexander polynomial. In this paper, we prove that for any integral homology sphere H, there exists an integer k such that H can be obtained from S3 by surgery on a boundary link each component of which has the Alexander polynomial 1+k(t½-t-½)2.