bluuebunny/crossref_metadata_2025 huggingface dataset:
Human interleukin‐6 induces human herpesvirus‐8 replication in a body cavity‐based lymphoma cell line
Authors: Song Jian , Ohkura Takako , Sugimoto Masamichi , Mori Yasuko , Inagi Reiko , Yamanishi Koichi , Yoshizaki Kazuyuki , Nishimoto Norihiro
Published: October 2002

Human herpesvirus‐8 (HHV‐8) is etiologically associated with Kaposi's sarcoma (KS), body cavity‐based lymphoma (BCBL), and multicentric Castleman's disease (MCD). These HHV‐8‐associated diseases arise predominantly in acquired immunodeficiency syndrome (AIDS) patients. Human interleukin‐6 (huIL‐6) elevated in the serum of AIDS patients is suggested to stimulate the growth of KS and BCBL and to augment the symptoms of MCD. To determine whether huIL‐6 stimulates HHV‐8 replication directly, expression of the HHV‐8 ORF‐50 immediate‐early gene (transcription activator) and ORF‐26 late lytic gene (a capsid protein) was assessed in a BCBL‐1 cell line stimulated by huIL‐6 by means of real‐time reverse transcription‐polymerase chain reaction. huIL‐6 induced both ORF‐50 and ORF‐26 expression, and the maximal ORF‐50 expression appeared earlier than that of ORF‐26. The data indicate that huIL‐6 reactivates HHV‐8 in BCBL‐1 cells through inducing ORF‐50. We also confirmed the previously reported activities of HHV‐8‐encoded huIL‐6 homologue (viral interleukin‐6 [vIL‐6]) on human immunodeficiency virus (HIV) replication in U1 cell line and huIL‐6 production by MT‐4 T cells, and utilizing monoclonal antibodies to the huIL‐6 receptor components, we elucidated that gp130 is the signaling molecule necessary for these vIL‐6 activities. These data suggest the possible existence of interaction between HIV and HHV‐8 via IL‐6, and that the blockade of IL‐6 signal by anti‐IL‐6R antibody or anti‐gp130 antibody can constitute a strategy to treat HIV/HHV‐8 dually infected patients. J. Med. Virol. 68:404–411, 2002. © 2002 Wiley‐Liss, Inc.
The woodchuck interferon‐α system: Cloning, family description, and biologic activity
Authors: Berraondo Pedro , García‐Navarro Raquel , González‐Aseguinolaza Gloria , Vales África , Blanco‐Urgoiti Begoña , Larrea Esther , Riezu‐Boj José Ignacio , Prieto Jesús , Ruiz Juan
Published: October 2002

Interferon‐α (IFN‐α) is a key element in the defense against viral infection because, in addition to a direct antiviral effect, it exhibits potent immunostimulatory activity. To investigate the function of this cytokine in the woodchuck model of chronic hepatitis B, the woodchuck IFN‐α gene (IFNA) family was cloned and examined. The data indicate that this is a multigenic family from which 12 IFNA functional sequences and four pseudogene sequences were isolated. The overall identity of the amino acid sequence among the members of the woodchuck IFN‐α family is 85%, and the identity with the IFN‐α family from other species such as mice and humans is 50%. The analysis of hepatic expression of IFNA genes showed that wIFNA5a was the subtype transcribed preferentially in the woodchuck liver. The wIFNA genes transcribed in the liver were tested in an eukaryotic expression system and were found to enhance 2–5‐oligoadenylate synthetase (2–5‐OAS) mRNA levels and to posses a potent antiviral activity. Cloning of woodchuck IFNA genes will allow testing diverse forms of IFN‐α delivery as well as different combination therapies in woodchuck hepatitis virus infection, thus providing useful information for the design of new strategies for the treatment of patients with chronic hepatitis B. J. Med. Virol. 68:424–432, 2002. © 2002 Wiley‐Liss, Inc.
Kinetics and mechanism of the reaction of para‐chlorophenyl aryl chlorophosphates with anilines in acetonitrile
Authors: Lee Hai Whang , Guha Arun Kanti , Lee Ikchoon
Published: October 2002

The kinetics and mechanism of the nucleophilic substitution reactions of p‐chlorophenyl aryl chlorophosphates (2) with anilines are investigated in acetonitrile at 55°C. Relatively large magnitudes of ρX and βX values are indicative of a large degree of bond making in the TS. Smaller magnitudes of ρX (0.20 for X = H) and ρXY (−0.30) than those for the corresponding reactions with phenyl aryl chlorophosphates (1) (ρX = 0.54 for X = H and ρXY = −1.31) are interpreted to indicate partial electron loss, or shunt, towards the electron acceptor equatorial ligand (p‐ClC6H4O‐) in the bipyramidal pentacoordinated transition state. The inverse secondary kinetic isotope effects (kH/kD = 0.64–0.87) involving deuterated aniline (ND2C6H4X) nucleophiles, and small ΔH‡ and large negative ΔS‡ are obtained. These results are consistent with a concerted nucleophilic substitution mechanism. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 632–637, 2002
Fluorescent in situ hybridization (FISH) reveals frequent and recurrent numerical and structural abnormalities in hepatoblastoma with no informative karyotype
Authors: Surace C. , Leszl A. , Perilongo G. , Rocchi M. , Basso G. , Sainati L.
Published: October 2002

Background

Hepatoblastoma (HB) is the most frequent malignant liver tumor in children. The few cytogenetic studies available indicate that HB is associated with recurring trisomies of chromosomes 2, 8, and 20; recurrent t(1;4) (q12;q34) has been reported in few cases. The abnormalities of chromosome 1q are relatively frequent and usually lead to overexpression of 1q material. A cluster of breakpoints is located at the level of bands 1q12 and 1q21. More work is needed to clarify their real incidence and prognostic significance. Cytogenetic analysis is limited by the requirement of suitable cells in metaphase. A different method that increases analysis sensitivity is fluorescent in situ hybridization (FISH).

Procedure

We studied 10 cases of HB with no informative karyotype (normal karyotype or no metaphases). FISH was performed by the standard method, using cytospins and imprints obtained from frozen or cytogenetic samples of direct cultures. Alpha‐satellite probes for centromeric DNA were used for chromosomes 2, 8, and 20 analysis; rearrangement of region 1q12‐21 was detected with BAC (bacterial artificial chromosome) probe bA79E5.

Results

We detected at least one trisomic clone in 5/10 of these cases. Trisomy 20 was the most frequently detected abnormality, followed by trisomy of the chromosomes 2 and 8. Analysis of 1q12 band revealed that the rearrangement of 1q usually is in pericentromeric heterochromatin, it was present in 5/10 of studied cases.

Conclusion

FISH analysis is recommended in all cases of HB with no informative karyotype to gain more information regarding the frequent trisomies encountered and their significance. Med Pediatr Oncol 2002;39:536–539. © 2002 Wiley‐Liss, Inc.
A time‐stepping method for stiff multibody dynamics with contact and friction
Authors: Anitescu Mihai , Potra Florian A.
Published: October 2002

We define a time‐stepping procedure to integrate the equations of motion of stiff multibody dynamics with contact and friction. The friction and non‐interpenetration constraints are modelled by complementarity equations. Stiffness is accommodated by a technique motivated by a linearly implicit Euler method. We show that the main subproblem, a linear complementarity problem, is consistent for a sufficiently small time step h. In addition, we prove that for the most common type of stiff forces encountered in rigid body dynamics, where a damping or elastic force is applied between two points of the system, the method is well defined for any time step h. We show that the method is stable in the stiff limit, unconditionally with respect to the damping parameters, near the equilibrium points of the springs. The integration step approaches, in the stiff limit, the integration step for a system where the stiff forces have been replaced by corresponding joint constraints. Simulations for one‐ and two‐dimensional examples demonstrate the stable behaviour of the method. Published in 2002 by John Wiley & Sons, Ltd.
Living radical graft polymerization of methyl methacrylate to polyethylene film with typical and reverse atom transfer radical polymerization
Authors: Yamamoto Katsuhiro , Miwa Youhei , Tanaka Hiroyuki , Sakaguchi Masato , Shimada Shigetaka
Published: October 2002

Nickel‐mediated atom transfer radical polymerization (ATRP) and iron‐mediated reverse ATRP were applied to the living radical graft polymerization of methyl methacrylate onto solid high‐density polyethylene (HDPE) films modified with 2,2,2‐tribromoethanol and benzophenone, respectively. The number‐average molecular weight (Mn) of the free poly(methyl methacrylate) (PMMA) produced simultaneously during grafting grew with the monomer conversion. The weight‐average molecular weight/number‐average molecular weight ratio (Mw/Mn) was small (<1.4), indicating a controlled polymerization. The grafting ratio showed a linear relation with Mn of the free PMMA for both reaction systems. With the same characteristics assumed for both free and graft PMMA, the grafting was controlled, and the increase in grafting ratio was ascribed to the growing chain length of the graft PMMA. In fact, Mn and Mw/Mn of the grafted PMMA chains cleaved from the polyethylene substrate were only slightly larger than those of the free PMMA chains, and this was confirmed in the system of nickel‐mediated ATRP. An appropriate period of UV preirradiation controlled the amount of initiation groups introduced to the HDPE film modified with benzophenone. The grafting ratio increased linearly with the preirradiation time. The graft polymerizations for both reaction systems proceeded in a controlled fashion. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3350–3359, 2002
1,4‐Addition polymerization of 1,4‐bis(4‐benzylpyridinium)butadiyne triflate in a dipolar aprotic solvent
Authors: Iwase Yoichiro , Kondo Koichi , Kamada Kenji , Ohta Koji
Published: October 2002

1,4‐Bis(4‐benzylpyridinium)butadiyne triflate was aggregated in dimethylformamide and spontaneously converted into the 1,4‐addition type of polydiacetylene. The polymerization took place in a dipolar aprotic solvent with a large dielectric constant that could enhance the aggregation of the ionic diacetylene salt through the electrostatic interaction. The molecular weight of the diacetylene was leveled off after 30 h at 80 °C to reach 1.5 × 104 (number‐average molecular weight) that consisted of the 1,4‐addition type of polydiacetylene similar to polydiacetylenes obtained in the conventional solid‐state polymerization. Electron spin resonance spectra revealed that diradicals were generated at the earlier state aggregation to give rise to a solution polymerization. The UV spectra also suggested the presence of the activated aggregation associated with the polymerization as well as the eximer emission spectra. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3534–3541, 2002
Molluscicidal and antifungal activity of Erigeron speciosus steam distillate
Authors: Meepagala Kumudini M , Sturtz George , Wise David , Wedge David E
Published: October 2002

The steam‐distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode, Bolbophorus confusus, that infests and causes severe infections in pond‐raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated antifungal activity in the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals toxic to P trivolvis. The bioactive compounds methyl 2Z, 8Z‐deca‐2,8‐diene‐4,6‐diynoate and its 2E, 8E isomer were isolated by bioassay‐guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy.

© 2002 Society of Chemical Industry
Neutralization of neutrophin‐3 in the ventral tegmental area or nucleus accumbens differentially modulates cocaine‐induced behavioral plasticity in rats
Authors: Freeman Antoinette Y. , Pierce R. Christopher
Published: October 2002

These experiments were designed to assess the influence of neurotrophin‐3 (NT‐3) and brain‐derived neurotrophic factor (BDNF) in the mesoaccumbens dopamine system on the initiation of behavioral sensitization to cocaine. A neutralizing antibody for NT‐3, BDNF or their vehicle was administered into the ventral tegmental area (VTA) or nucleus accumbens prior to each of four daily injections of 15 mg/kg cocaine. Behavioral sensitization was operationally defined as a significant increase in the behavioral response to cocaine relative to the first daily injection. Results indicated that the NT‐3 antibody had differential effects when administered into the VTA or nucleus accumbens. Intra‐VTA microinjection of anti‐NT‐3 resulted in enhanced sensitization to repeated cocaine injections in that the cocaine‐induced behavioral response in the anti‐NT‐3 group was significantly greater than the vehicle group following the second and third daily injections of cocaine. Administration of anti‐NT‐3 into the nucleus accumbens increased the behavioral response to cocaine over all 4 days of cocaine administration, with no sensitization of this behavioral response. In contrast, pretreatment with anti‐BDNF into the VTA or nucleus accumbens had no influence on the initiation of behavioral sensitization to cocaine. Taken together, these data indicate that neutralization of NT‐3 in the VTA enhances cocaine‐induced behavioral sensitization, while administration of the NT‐3 antibody into the nucleus accumbens increases the hyperactive behavioral response induced by cocaine but impairs the further development of behavioral sensitization. Synapse 46:57–65, 2002. © 2002 Wiley‐Liss, Inc.
New Genes for Phylogenetic Studies of Lichenized Fungi: Glyceraldehyde-3-Phosphate Dehydrogenase and Beta-Tubulin Genes
Authors: Myllys Leena , Stenroos Soili , Thell Arne
Published: October 2002

Primers for amplification and sequencing of partial glyceraldehyde-3-phosphate dehydrogenase (gpd) gene were designed for lichenized fungi. The 5’ gpd primer is most probably fungal specific, since a BLAST search in GenBank found identical sequences only from ascomycetous taxa, whereas the 3’ gpd primer was more universal. Utility of the gpd primers and previously designed beta-tubulin primers was tested in nine lichen taxa. Both the gpd and beta-tubulin primer pairs amplified in most of the taxa examined: the gpd primers generated a c. 1100 nucleotide fragment, whereas the PCR product obtained from the beta-tubulin primers was c. 900 nucleotides long. The gpd amplification products of Cladonia arbuscula and C. rangiferina were sequenced and both were found to contain three introns, the length of which varied between 49 to 83 nucleotides. To examine the applicability of gpd sequences in resolving relationships within Ascomycota, trees were calculated from 22 fungal gpd sequences obtained from GenBank together with the two Cladonia sequences using parsimony jackknifing. The gpd tree was compared with the SSU rDNA tree of the respective species (or genera). A similar analysis of the beta-tubulin gene was not performed, because only a few beta-tublin sequences from the same taxa were available in GenBank. The gpd tree was well resolved but in conflict with the SSU rDNA tree. In contrast to the SSU rDNA tree, the gpd tree did not support the monophyly of the Ascomycota. Analysis of the combined data set produced a tree very similar to that of the SSU rDNA data. However, the relationship of Lecanorales to the other orders remained unresolved. Even though gpd and beta-tubulin are highly conserved proteins, the third codon positions and introns are variable and both genes have the potential for inferring phylogenetic relationships at the lower taxonomic levels in the lichenized fungi. The two genes may be useful even below species level, depending on the species investigated.
Maternal deaths associated with cesarean section in Enugu, Nigeria
Authors: Ozumba B.C , Anya S.E
Published: October 2002

Maternal deaths from cesarean sections in Nigeria are exceptionally high and result from avoidable causes such as hemorrhagic shock, sepsis and hypertensive disorders in pregnancy. Increased involvement of specialists in the care and improved intra and post‐operative management of cases are advocated to reduce the high maternal mortality rate.
Multisensory integration for spatial orientation in trait anxiety subjects: absence of visual dependence
Authors: Viaud-Delmon I. , Berthoz A. , Jouvent R.
Published: October 2002

Studies suggest a greater reliance on visual information for maintaining balance in anxious subjects. Nevertheless, links between this supposed preferred visual processing and spatial orientation have not yet been evaluated. Two groups of subjects differing in their level of trait anxiety were formed. Equipped with a head-mounted visual display, they learned a virtual corridor using passive translation but active rotation, both with normal and with two different conflicting sensory conditions. After two visual navigation trials in the corridor, they were blindfolded and asked to reproduce the same trajectory from memory. In addition, subjects drew a map of the remembered corridor. Anxious subjects were comparable to non-anxious subjects when asked to reproduce the trajectory from memory, but exhibited a deficit when drawing a map of the corridor they were in. The results do not support the hypothesis that anxious subjects use preferentially one type of sensory cue over another for spatial orientation, but instead manifest difficulties in constructing more global representations of space.
Surface coatings for fluxless soldering of copper
Authors: Liu Changqing , Hutt David A.
Published: October 2002

The solder interconnection of components to printed circuit boards normally utilises a flux to enable the efficient removal of oxide layers from the metals to be joined. While this produces a strong metallurgical bond, the flux residue left behind after the soldering process can be detrimental to the long‐term performance of the product. Therefore, after assembly, a cleaning process is often employed to remove the residue, however, this incurs extra financial and environmental costs. In this work, organic coatings have been used to preserve copper surfaces in an oxide free state, enabling fluxless soldering to take place. These coatings, if stored appropriately, were found to be effective in preventing the oxidation of copper for several weeks, however, they are readily displaced by the soldering process allowing the active copper surface to be wetted. Wetting balance testing and surface analysis have been used to assess the preservation of copper coupons following storage in air.
QUANTUM-LIOUVILLE AND LANGEVIN EQUATIONS FOR GRAVITATIONAL RADIATION DAMPING
Authors: HABA Z. , KLEINERT H.
Published: October 2002

From a forward–backward path integral, we derive a master equation for the emission and absorption of gravitons by a massive quantum object in a heat bath of gravitons. Such an equation could describe the collapse phenomena of dense stars. We also present a useful approximate Langevin equation for such a system.
Evaluation of Aquatic Environment by Polyaromatic Hydrocarbon Concentration and Induction of EROD Activity in HepG2 Cells
Authors: Nagashima Hiroshi , Ono Yoshiro , Sekiguchi Motochika
Published: October 2002

Environmental contamination by polyaromatic hydrocarbons (PAHs) and dioxin-like compounds was evaluated by chemical analysis and biological tests. Though soils and road dust samples revealed more potent biological activities than incinerator ashes, the contribution of PAHs were low.
A New Class of High-Performance Red-Fluorescent Dyes for Organic Electroluminescent Devices, [7-Diethylamino-3-(2-thienyl)chromen-2-ylidene]-2,2-dicyanovinylamine and {10-(2-Thienyl)-2,3,6,7-tetrahydro-1H,5H-chromeno[8,7,6-ij]quinolizin-11-ylidene}-2,2-dicyanovinylamine
Authors: Yu Junsheng , Shirota Yasuhiko
Published: October 2002

A new and better generation of red-fluorescent dyes based on a chromene-2-ylidene moiety, [7-diethylamino-3-(2-thienyl)chromen-2-ylidene]-2,2-dicyanovinylamine (ACY) and {10-(2-thienyl)-2,3,6,7-tetrahydro-1H,5H-chromeno[8,7,6-ij]quinolizin-11-ylidene}-2,2-dicyanovinylamine (CQY), has been designed and synthesized, and has been proven to function as excellent red-emitting dopants in high-performance red-emitting organic electroluminescent devices.
Crystal Structure of a Luminescent Complex Sm(HTH)3Phen
Authors: Guo Junfang , Fu Lianshe , Li Huanrong , Zheng Youxuan , Liu Fengyi , Meng Qingguo , Wang Jun , Zhang Hongjie
Published: October 2002

The crystal structure of Sm(HTH)3Phen [HTH: 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)-1,3-hexanedione, Phen: 1,10-Phenanthroline] has been determined by single crystal X-ray diffraction and the coordination geometry of Sm atom is a dodecahedron. The complex can give the characteristic luminescence of Sm3+ upon UV excitation.
1/r
-potential without charge
Authors: Buchner K.
Published: September 2002

In order to get geodesically complete Reißner–Nordstrøm space–times, it is necessary to identify pairs of singular points. This can be done in such a way that “wormholes” are created which generate electric field lines without any charge. Finally, it is shown that it is possible to glue this space–time not in the singularities r=0, but at some r>0. The surface energy generated by this gluing is exotic, but tends to zero in the limit r→0.
Thermodynamic Quantities for the Ionization Reactions of Buffers
Authors: Goldberg Robert N. , Kishore Nand , Lennen Rebecca M.
Published: September 2002

This review contains selected values of thermodynamic quantities for the aqueous ionization reactions of 64 buffers, many of which are used in biological research. Since the aim is to be able to predict values of the ionization constant at temperatures not too far from ambient, the thermodynamic quantities which are tabulated are the pK, standard molar Gibbs energy ΔrG∘, standard molar enthalpy ΔrH°, and standard molar heat capacity change ΔrCp∘ for each of the ionization reactions at the temperature T=298.15 K and the pressure p=0.1 MPa. The standard state is the hypothetical ideal solution of unit molality. The chemical name(s) and CAS registry number, structure, empirical formula, and molecular weight are given for each buffer considered herein. The selection of the values of the thermodynamic quantities for each buffer is discussed.
Enthalpies of Sublimation of Organic and Organometallic Compounds. 1910–2001
Authors: Chickos James S. , Acree William E.
Published: September 2002

A compendium of sublimation enthalpies, published within the period 1910–2001 (over 1200 references), is reported. A brief review of the temperature adjustments for the sublimation enthalpies from the temperature of measurement to the standard reference temperature, 298.15 K, is included, as are recently suggested values for several reference materials. Sublimation enthalpies are included for organic, organometallic, and a few inorganic compounds.
Semiclassical generalization of the Darboux–Christoffel formula
Authors: Littlejohn Robert G. , Wright Paul
Published: September 2002

The Darboux–Christoffel formula is a closed-form expression for the kernel of the operator that projects onto the first N of a system of one-dimensional polynomials, orthonormal with respect to some weighting function. It is a key element in the theory of Gaussian integration and in the theory of discrete variable representation or Lagrangian mesh methods for diagonalizing quantum Hamiltonians of a few degrees of freedom. The one-dimensional Darboux–Christoffel formula turns out to have a generalization that is valid in a semiclassical or asymptotic sense for a wider class of orthonormal functions than orthonormal polynomials. This class consists of the bound eigenfunctions of one-dimensional Hamiltonians with time-reversal invariance, such as kinetic-plus-potential Hamiltonians. It also has certain generalizations involving the unbound eigenfunctions of such Hamiltonians.
d
-dimensional Lévy flights: Exact and asymptotic
Authors: Garoni T. M. , Frankel N. E.
Published: September 2002

The analytic and asymptotic properties of the spherically symmetric d-dimensional Lévy stable probability density function, pαd(r), are discussed in detail. These isotropic stable probability density functions (pdfs) are analogous to the one-dimensional symmetric Lévy stable pdfs previously studied by the present authors [J. Math. Phys. 43, 2670 (2002)]. We construct a hypergeometric representation of pαd(r) when α is rational, and find a number of new representations of pαd(r) in terms of special functions for various values of d and α. A recursion relation is found between pαd(r) and pαd+2(r), which, in particular, implies there exists a simple map between pα1(r) and pα3(r). As in our previous paper, we discuss the properties of pαd(r) for both the cases α⩽2 and α>2. We demonstrate the existence of intricate exponentially small series in the large r asymptotics of pαd(r) when α is an integer, which are dominant when α is even. We explicitly construct this beyond all orders expansion of pαd(r) for arbitrary integral α and d.
Extensive form of equilibrium nonextensive statistics
Authors: Wang Qiuping A. , Le Méhauté Alain
Published: September 2002

It is argued that, in nonextensive statistical mechanics with Tsallis entropy, the factorization of compound probability over subsystems is a consequence of the existence of thermodynamic equilibrium in the composite system and should be respected by all exact calculations concerning equilibrium subsystems. Using nonadditive energy satisfying this factorization, we propose an additive formalism of nonextensive statistical mechanics with additive q-deformed physical quantities and exponential distributions. This formalism leads to exact quantum gas distributions different from those given by factorization approximation with additive energy. The fermion distribution of the present work shows similar characteristics to the distribution of strongly correlated electrons given by numerical analysis with the Kondo t-J model.
Multipole expansion of a plane wave
Authors: Torres del Castillo G. F. , Hernández-Moreno F. J.
Published: September 2002

The spherical components of the multipole expansion of a plane wave with arbitrary spin are obtained in terms of spin-weighted spherical harmonics. It is shown that the expansion coefficients are essentially spin-weighted spherical harmonics evaluated at the direction of propagation of the wave.
The peculiarity of a negative coordinate axis in dyonic solutions of noncommutative N=4 super Yang–Mills
Authors: Misra Aalok
Published: September 2002

We show that in the neighborhood of a negative coordinate axis, the U(1) sector of the static dyonic solutions to the noncommutative U(4) N=4 super Yang–Mills (SYM) can be consistently decoupled from the SU(4) to all orders in the noncommutativity parameter. We show the above decoupling in two ways. First, we show the noncommutative dyon being the same as the commutative dyon, is a consistent solution to noncommutative equations of motion in the abovementioned region of noncommutative space. Second, as an example of decoupling of a non-null U(1) sector, we also obtain a family of solutions with nontrivial U(1) components for all components of the gauge field in the same region of noncommutative space. In both cases, the SU(4) and U(1) components separately satisfy the equations of motion.
Twistor representation of null two-surfaces
Authors: Ilyenko Kostyantin
Published: September 2002

We present a twistor description for null two-surfaces (null strings) in four-dimensional Minkowski space–time. The Lagrangian density for a variational principle is taken as a surface-forming null bivector. The proposed formulation is reparametrization invariant and free of any algebraic and differential constraints. The spinor formalism of Cartan–Penrose allows us to derive a nonlinear evolution equation for the world-sheet coordinate xa(τ,σ). An example of null two-surface given by the two-dimensional self-intersection (caustic) of a null hypersurface is studied.
On three-dimensional coupled bosons
Authors: Turgut O. Teoman
Published: September 2002

In this work we study two complex scalar fields coupled through a quadratic interaction in 2+1 dimensions using the method of bilinears as suggested by Rajeev [Int. J. Mod. Phys. A 9, 5583 (1994)]. The resulting theory can be formulated as a classical theory. We study the linear approximation, and show that there is a possible bound state in a range of coupling constants.
Direct calculation of thermodynamic quantities for the Heisenberg model
Authors: Kato Go , Wadati Miki
Published: September 2002

The XXX Heisenberg model is studied at finite temperature. The free energy is derived without recourse to thermal Bethe ansatz method and quantum transfer matrix method. The result perfectly agrees with the free energy derived by thermal Bethe ansatz method. An explicit expression of the cluster expansion coefficient in arbitrary order is presented for the first time.
Separation of variables and exact solution of the Klein–Gordon and Dirac equations in an open universe
Authors: Villalba Vı́ctor M. , Catalá Esteban Isasi
Published: September 2002

We solve the Klein–Gordon and Dirac equations in an open cosmological universe with a partially horn topology in the presence of a time dependent magnetic field. Since the exact solution cannot be obtained explicitly for arbitrary time dependence of the field, we discuss the asymptotic behavior of the solutions with the help of the relativistic Hamilton–Jacobi equation.
On the magnetohydrodynamic Kelvin–Helmholtz instability driven by a nonuniform ion drift
Authors: Vranješ J. , Tanaka M. Y.
Published: September 2002

An analytical study of the stability of perturbations propagating along a nonuniform ion drift, which includes both the E×B and the ion diamagnetic drifts, in a magnetohydrodynamic plasma immersed in a nonuniform magnetic field, is presented. The behavior of stable and unstable modes is studied in the case when the shear flow is described by an analytical tanh(x)-type ion drift. A threshold for the wave-number is obtained analytically and a perturbative analysis is performed around the threshold. It is shown that modes with wave-numbers that are less than the threshold gain energy from the shear flow and are therefore unstable, which is in agreement with well-known instability criteria obtained numerically.
Precision matched solution of the coupled beam envelope equations for a periodic quadrupole lattice with space charge
Authors: Lee Edward P.
Published: September 2002

The coupled Kapchinskij–Vladimirskij (K–V) envelope equations for a charged particle beam transported by a periodic system of quadrupoles with self-consistent space charge force have previously been solved by various approximate methods, with accuracy ranging from 1% to 10%. A new method of solution is introduced here, which is based on a double expansion of the beam envelope functions in powers of the focal strength and either the beam’s emittance or its dimensionless perveance. This method results in accuracy better than 0.1% for typical lattice and beam parameters when carried through one consistent level of approximation higher than employed in previous work. Several useful quantities, such as the values of the undepressed tune and the beam’s perveance in the limit of vanishing emittance, are represented by very rapidly converging power series in the focal strength, with an accuracy of 0.01% or better.
Drift wave vortices in multicomponent plasmas
Authors: Gogoi G. , Goswami K. S.
Published: September 2002

The effect of negative ions in the dynamics of the drift vortex in inhomogeneous plasma is analytically studied. It is found that when the drift velocity is not constant, vortex solutions exist only in the short wavelength region. It is observed that the gradient of drift velocity is responsible for the formation of monopole vortices.
Forward and backward stimulated Brillouin scattering in a nonuniform plasma
Authors: Cohen B. I. , McKinstrie C. J. , Startsev E. A.
Published: September 2002

The simultaneous forward and backward stimulated Brillouin scattering of a laser beam in a nonuniform plasma is studied. Analytical solutions of the steady-state nonlinear equations are presented, and the dependencies of the forward and backward scattering on the physical parameters and the noise boundary conditions are assessed.
Geometric quantization of time-dependent completely integrable Hamiltonian systems
Authors: Fiorani E. , Giachetta G. , Sardanashvily G.
Published: September 2002

A time-dependent completely integrable Hamiltonian system is quantized with respect to time-dependent action-angle variables near an instantly compact regular invariant manifold. Its Hamiltonian depends only on action variables, and has a time-independent countable energy spectrum.
Hamiltonian structures on foliations
Authors: Vaisman Izu
Published: September 2002

We discuss Hamiltonian structures of the Gelfand–Dorfman complex of projectable vector fields and differential forms on a foliated manifold. Such a structure defines a Poisson structure on the algebra of foliated functions, and embeds the given foliation into a larger, generalized foliation with presymplectic leaves. In a so-called tame case, the structure is induced by a Poisson structure of the manifold. Cohomology spaces and classes relevant to geometric quantization are also considered.
On the node in the current density profile during current peaking in a sawtooth oscillation
Authors: Chu T. K.
Published: September 2002

The measured location of current node in sawtooth oscillation, rn, by Soltwisch et al. can be explained by employing the principle of minimum energy dissipation and current conservation within the q=1 surface (at r1). djφ/dq0=0 requires rn/r1=[q0/(1+q0)]1/2.
Time-dependent solution for a star immersed in a background radiation
Authors: Liu Hongya , Zhang Qiuyang
Published: September 2002

We study a time-dependent and spherically symmetric solution with a starlike source. We show that this solution can be interpreted as an exterior solution of a contracting star which has a decreasing temperature and is immersed in a homogenous and isotropic background radiation. Distribution of the temperature in the fields and close-to-Schwarzschild approximation of the solution are studied. By identifying the radiation with the cosmic background one, we find that the close-to-Schwarzschild approximate solution is valid in a wide range in our solar system. Possible experimental tests of the solution are discussed briefly.
Finite-dimensional Lie algebras of order F
Authors: Rausch de Traubenberg M. , Slupinski M. J.
Published: September 2002

F-Lie algebras are natural generalizations of Lie algebras (F=1) and Lie superalgebras (F=2). When F>2 not many finite-dimensional examples are known. In this article we construct finite-dimensional F-Lie algebras F>2 by an inductive process starting from Lie algebras and Lie superalgebras. Matrix realizations of F-Lie algebras constructed in this way from su(n),sp(2n) so(n) and sl(n|m), osp(2|m) are given. We obtain nontrivial extensions of the Poincaré algebra by Inönü–Wigner contraction of certain F-Lie algebras with F>2.
Hamiltonian flow associated with a two-dimensional map
Authors: Saito Satoru , Shudo Akira , Yamamoto Jun-ichi , Yoshida Katsuhiko
Published: September 2002

For a given differentiable map (x,y)→(X(x,y),Y(x,y)), which has an inverse, we show that there exists a Hamiltonian flow in which x plays the role of the time variable while y is fixed.
Complex velocity transformations and the Bisognano–Wichmann theorem for quantum fields acting on Krein spaces
Authors: Gottschalk Hanno
Published: September 2002

It is proven that in indefinite metric quantum field theory there exists a dense set of analytic vectors for the generator of the one parameter group of x0–x1 velocity transformations. This makes it possible to define complex velocity transformations also for the indefinite metric case. In combination with the results of Bros, Epstein, and Moschella [Commun. Math. Phys. 196, 535–570 (1998)], proving Bisognano–Wichmann (BW) analyticity within the linear program, one then obtains a suitable generalization of the BW theorem for local, relativistic quantum fields acting on Krein spaces (“quantum fields with indefinite metric”).
Exponential factors and Darbouxian first integrals of the Lorenz system
Authors: Zhang Xiang
Published: September 2002

In this article we characterize all the exponential factors and the Darbouxian first integrals for the Lorenz system ẋ=s(y−x),  ẏ=rx−y−xz,  ż=−bz+xy. In the proofs, we use the weight homogeneous polynomials and the method of characteristic curves for solving linear partial differential equations.
Thermal instability analysis of different types of density limits in DIII-D gas fueled, high-mode discharges
Authors: Stacey W. M. , Petrie T. W. , Osborne T. H.
Published: September 2002

High density, gas fueled, high confinement mode, DIII-D [Luxon, Anderson, Batty et al., Plasma Physics and Controlled Nuclear Fusion Research 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. 1, p. 159] shots that were limited in density buildup by: (1) an H–L (high-to-low confinement mode) transition apparently triggered by a core X-point MARFE (multifaceted asymmetric radiation from edge), following the thermal instability sequence of detachment-divertor MARFE-core X-point MARFE; (2) a density limit apparently triggered by large scale core magnetohydrodynamic activity; and (3) an H–L transition apparently triggered by excessive radiated power from the plasma core are analyzed. The presence or absence of a MARFE was correctly predicted by thermal instability theory. A sharp edge temperature gradient was identified as an important factor inhibiting the usual detachment-MARFE sequence in DIII-D and thus leading to the achievement of higher density.
Unified theory of monochromatic and broadband modulational and decay instabilities of Langmuir waves
Authors: Robinson P. A. , Cairns Iver H. , Smith N. I.
Published: September 2002

Modulational and decay instabilities driven by pump Langmuir waves are investigated using a nonlinear dispersion equation that incorporates both classes of instability simultaneously, along with the effects of finite bandwidth of the pump. A rational-function approximation of the plasma density response is then introduced to convert this equation into polynomial form. The resulting equation is used to explore the five instability types: decay, modulational, subsonic modulational, supersonic modulational, and modified decay. Growth rates, corresponding wave numbers, stability boundaries, and instability thresholds for the various instabilities are obtained analytically and verified numerically. In the case of a monochromatic pump the results generalize and clarify the limits of validity of many results in the literature. For broadband pumps, existing results for the growth rate of decay instabilities are reproduced, and it is confirmed that broadband modulational and subsonic-modulational interactions are necessarily stable. New results for the behavior of supersonic modulational instabilities are found, and it is also shown that both supersonic modulational and modified decay instabilities have random phase counterparts, the former conclusion contrasting with implications in the literature. The parameter-space transition between modulational and decay instability classes is found to be much sharper than between instability types within either of these classes.
Presheath/sheath model with secondary electron emission from two parallel walls
Authors: Ahedo E.
Published: September 2002

A macroscopic model of the interaction of a plasma with two parallel, electron-emitting walls is presented. Zero Debye-length and total thermalization of the secondary electron emission (SEE) are assumed. The SEE is treated as a free beam within each thin, collisionless sheath, but as part of a single electron population within the presheath. Plasma models with three and two species result in sheath and presheath, respectively. The ion flow at the presheath/sheath transition is sonic, and the sound speed there determines the relation between the temperature of the confined electron populations in sheath and presheath. For the general case of a plasma flowing axially between two annular walls the complete dimensionless solution depends on five parameters. Potential drops in the presheath can be larger than in the sheaths, mainly when charge-saturation is reached in the sheath or for a large effective ion friction in the presheath. The losses of plasma current to the walls are determined totally by the presheath problem, whereas the sheath problem and wall material determine the energy lost by impacting particle. Energy losses change drastically from zero SEE to a SEE yield about 100% when the charge-saturated regime is reached.
Collisionless reconnection of magnetic field lines in dusty plasmas
Authors: Jovanović D. , Shukla P. K.
Published: September 2002

Stability of a thin current sheet in an inhomogeneous dusty plasma is investigated. A new mechanism for the collisionless reconnection of the magnetic field is found. It is associated with the linear instability of a surface shear-Alfvén mode which exists at the boundary between two plasma regions with different orientations of the sheared magnetic field. This new mode is possible only in dusty plasmas in which the electron and ion densities are inhomogeneous and different from each other. The dispersion properties of the surface mode are found to be strongly dependent on the spatial profile of the current sheet. The unstable linear mode is found in the case of a current sheet with steep edges. It is identified as the bending- (or kink-) mode, whose electrostatic and vector potentials, φ and Az, are symmetric and antisymmetric functions, respectively. In such a plasma configuration, the surface tearing mode (φ-antisymmetric, Az-symmetric) cannot propagate as an eigenmode. It arises only as a forced mode through the resonant coupling with the bending mode and the local convective cell. The increment of the bending/tearing instability is estimated from the second-order contribution of the resonance.
A bidirectional Kaup–Kupershmidt equation and directionally dependent solitons
Authors: Dye J. M. , Parker A.
Published: September 2002

Exact multisoliton solutions are obtained for the bidirectional Kaup–Kupershmidt equation that was reported in a recent paper [J. Math. Phys. 42, 2567 (2001)]—this fills the gap that was left in the prior study. These solutions are found to possess the same remarkable, and unusual, property as the solitary-wave solution; namely, their wave profiles are directionally dependent. In particular, solitons are presented which describe multiple “head-on” collisions between single- and double-humped solitary waves. Explicit expressions are given for the first few multisoliton solutions and a procedure is described for constucting the general N-soliton by iteration on the solitons of lower order.
Becchi–Rouet–Stora–Tyutin quantization of histories electrodynamics
Authors: Noltingk Duncan
Published: September 2002

This article is a continuation of earlier work where a classical history theory of pure electrodynamics was developed in which the history fields have five components. The extra component is associated with an extra constraint, thus enlarging the gauge group of histories electrodynamics. In this article we quantize the classical theory developed previously by two methods. First we quantize the reduced classical history space to obtain a reduced quantum history theory. Second we quantize the classical BRST-extended history space, and use the Becchi–Rouet–Stora–Tyutin charge to define a “cohomological” quantum history theory. Finally, we show that the reduced history theory is isomorphic (as a history theory) to the cohomological history theory.
The two-dimensional hydrogen atom revisited
Authors: Parfitt D. G. W. , Portnoi M. E.
Published: September 2002

The bound-state energy eigenvalues for the two-dimensional Kepler problem are found to be degenerate. This “accidental” degeneracy is due to the existence of a two-dimensional analog of the quantum-mechanical Runge–Lenz vector. Reformulating the problem in momentum space leads to an integral form of the Schrödinger equation. This equation is solved by projecting the two-dimensional momentum space onto the surface of a three-dimensional sphere. The eigenfunctions are then expanded in terms of spherical harmonics, and this leads to an integral relation in terms of special functions which has not previously been tabulated. The dynamical symmetry of the problem is also considered, and it is shown that the two components of the Runge–Lenz vector in real space correspond to the generators of infinitesimal rotations about the respective coordinate axes in momentum space.
Laser Mégajoule irradiation uniformity for direct drive
Authors: Canaud B. , Fortin X. , Dague N. , Bocher J. L.
Published: September 2002

In the context of the direct-drive Laser-Mégajoule (LMJ) fusion-research program, the characteristic long-wavelength nonuniformities produced by irradiating a pellet with multiple overlapping laser beams are studied with or without imperfections coming from power imbalance and pointing errors. The intensity profiles are modeled by super-Gaussian shapes. The beam pattern which minimizes the intrinsic LMJ nonuniformity is determined. It is shown the LMJ beam placement creates untractable nonuniformities from even modes. The laser imperfections create odd and low modes of nonuniformity which can dominate the even modes.
Extended Leibovich–Roberts equation in rarefied plasmas
Authors: Ballai Istvan , Zhugzhda Yuzef D.
Published: September 2002

Weakly nonlinear magnetoacoustic waves in thin magnetic flux tubes are investigated in rarefied plasmas when an anisotropic kinetic pressure is taken into account. The parallel and perpendicular pressures are defined by two polytropic pressure laws. This model can be considered as a natural extension of the magnetohydrodynamics approximation when the plasma is rarefied. The dispersion relation for slow surface sausage waves propagating in magnetically embedded flux tubes in the presence of pressure anisotropy is used to derive the extended Leibovich–Roberts equation in rarefied and anisotropic plasmas. The properties and limitations of this equation are discussed.
Nonlinear electrostatic oscillations in a thermal dusty plasma
Authors: Houili H. , Tribeche M. , Aoutou K.
Published: September 2002

Stationary nonlinear one-dimensional electrostatic oscillations in a plasma containing a cold beam of dust grains along with warm beams of electrons and ions are considered. It is found that the thermal effects do not affect the qualitative nature of the solutions already given by the authors, for a cold model, in a previous work [M. Tribeche et al., Phys. Plasmas 9, 419 (2002)]. Nevertheless, it is found that only negative potential structures associated with the nonlinear localized waves can exist in such a dusty plasma model.
Hall effect in noncommutative coordinates
Authors: Dayi Ömer F. , Jellal Ahmed
Published: September 2002

We consider electrons in uniform external magnetic and electric fields which move on a plane whose coordinates are noncommuting. Spectrum and eigenfunctions of the related Hamiltonian are obtained. We derive the electric current whose expectation value gives the Hall effect in terms of an effective magnetic field. We present a receipt to find the action which can be utilized in path integrals for noncommuting coordinates. In terms of this action we calculate the related Aharonov–Bohm phase and show that it also yields the same effective magnetic field. When magnetic field is strong enough this phase becomes independent of magnetic field. Measurement of it may give some hints on spatial noncommutativity. The noncommutativity parameter θ can be tuned such that electrons moving in noncommutative coordinates are interpreted as either leading to the fractional quantum Hall effect or composite fermions in the usual coordinates.