bluuebunny/crossref_metadata_2025 huggingface dataset:
Superantigen Expression Is Driven by Both Mouse Mammary Tumor Virus Long Terminal Repeat-Associated Promoters in Transgenic Mice
Authors: Salmons Brian , Miethke Thomas , Wintersperger Stefan , Müller Mathias , Brem Gottfried , Günzburg Walter H.
Published: July 2002

In addition to the usual retroviral promoter, the mouse mammary tumor virus (MMTV) long terminal repeat carries a second promoter located in the U3 region. Here we show that both of these promoters are independently able to give rise to superantigen activity in transgenic mice. The ability of multiple MMTV promoters to drive superantigen expression underscores its importance in the virus life cycle.
Generation of Cytomegalovirus-Specific Human T-Lymphocyte Clones by Using Autologous B-Lymphoblastoid Cells with Stable Expression of pp65 or IE1 Proteins: a Tool To Study the Fine Specificity of the Antiviral Response
Authors: Retière Christelle , Prod'homme Virginie , Imbert-Marcille Berthe-Marie , Bonneville Marc , Vié Henri , Hallet Marie-Martine
Published: July 2002

Cytotoxic T lymphocytes (CTLs) play a central role in the control of persistent human cytomegalovirus (HCMV) infection in healthy virus carriers. Previous analyses of the specificity of HCMV-reactive CD8+CTLs drawn from in vitro models in which antigen-presenting cells were autologous fibroblasts infected with laboratory HCMV strains have shown focusing of CTL responses against the major tegument protein, pp65. By contrast, the 72-kDa major immediate-early protein (IE1) was identified as a minor target for this response. Here we have studied the fine specificity and T-cell-receptor features of T-cell clones generated against autologous B lymphoblastoid cell lines stably transfected with HCMV cDNA coding for either pp65 or a natural variant of IE1. This strategy allowed efficient generation of T-cell clones against IE1 and pp65 and led to the identification of several new IE1 and pp65 epitopes, including some located in polymorphic regions of IE1. Such an approach may provide relevant information about the characteristics of the CTL response to IE1 and the effect of viral polymorphism on the immune response against HCMV.
Identification of Two Sequences in the Cytoplasmic Tail of the Human Immunodeficiency Virus Type 1 Envelope Glycoprotein That Inhibit Cell Surface Expression
Authors: Bültmann Andreas , Muranyi Walter , Seed Brian , Haas Jürgen
Published: July 2002

During synthesis and export of protein, the majority of the human immunodeficiency virus type 1 (HIV-1) Env glycoprotein gp160 is retained in the endoplasmic reticulum (ER) and subsequently ubiquitinated and degraded by proteasomes. Only a small fraction of gp160 appears to be correctly folded and processed and is transported to the cell surface, which makes it difficult to identify negative sequence elements regulating steady-state surface expression of Env at the post-ER level. Moreover, poorly localized mRNA retention sequences inhibiting the nucleocytoplasmic transport of viral transcripts interfere with the identification of these sequence elements. Using two heterologous systems with CD4 or immunoglobulin extracellular/transmembrane domains in combination with the gp160 cytoplasmic domain, we were able to identify two membrane-distal, neighboring motifs,is1(amino acids 750 to 763) andis2(amino acids 764 to 785), which inhibited surface expression and induced Golgi localization of the chimeric proteins. To prove that these two elements act similarly in the homologous context of the Env glycoprotein, we generated a synthetic gp160 gene with synonymous codons, the transcripts of which are not retained within the nucleus. In accordance with the results in heterologous systems, an internal deletion of both elements considerably increased surface expression of gp160.
Simian Virus 40 Large-T-Antigen-Specific Rejection of mKSA Tumor Cells in BALB/c Mice Is Critically Dependent on both Strictly Tumor-Associated, Tumor-Specific CD8+Cytotoxic T Lymphocytes and CD4+T Helper Cells
Authors: Utermöhlen Olaf , Schulze-Garg Christine , Warnecke Gabriele , Gugel Roland , Löhler Jürgen , Deppert Wolfgang
Published: July 2002

Protective immunity of BALB/c mice immunized with simian virus 40 (SV40) large T antigen (TAg) against SV40-transformed, TAg-expressing mKSA tumor cells is critically dependent on both CD8+and CD4+T lymphocytes. By depleting mice of T-cell subsets at different times before and after tumor challenge, we found that at all times, CD4+and CD8+cells both were equally important in establishing and maintaining a protective immune response. CD4+cells do not contribute to tumor eradication by directly lysing mKSA cells. However, CD4+lymphocytes provide help to CD8+cells to proliferate and to mature into fully active cytotoxic T lymphocytes (CTL). Depletion of CD4+cells by a single injection of CD4-specific monoclonal antibody at any time from directly before injection of the vaccinating antigen to up to 7 days after tumor challenge inhibited the generation of cytolytic CD8+lymphocytes. T helper cells in this system secrete the typical Th-1 cytokines interleukin 2 (IL-2) and gamma interferon. Because in this system TAg-specific CD8+cells secrete only minute amounts of IL-2, it appears that T helper cells provide these cytokines for CD8+T cells. Moreover, this helper effect of CD4+T cells in mKSA tumor rejection in BALB/c mice does not simply improve the activity of TAg-specific CD8+CTL but actually enables them to mature into cytolytic effector cells. Beyond this activity, the presence of T helper cells is necessary even in the late phase of tumor cell rejection in order to maintain protective immunity. However, despite the support of CD4+T helper cells, the tumor-specific CTL response is so weak that only at the site of tumor cell inoculation and not in the spleen or in the regional lymph nodes can TAg-specific CTL be detected.
Sequence Requirements for Sindbis Virus Subgenomic mRNA Promoter Function in Cultured Cells
Authors: Wielgosz Matthew M. , Raju Ramaswamy , Huang Henry V.
Published: July 2002

The Sindbis virus minimal subgenomic mRNA promoter (spanning positions −19 to +5 relative to the subgenomic mRNA start site) is approximately three- to sixfold less active than the fully active −98 to +14 promoter region. We identified two elements flanking the −19 to +5 region which increase its transcription to levels comparable to the −98 to +14 region. These elements span positions −40 to −20 and +6 to +14 and act synergistically to enhance transcription. Nine different virus libraries were constructed containing blocks of five randomized nucleotides at various positions in the −40 to +14 region. On passaging these libraries in mosquito cells, a small subset of the viruses came to dominate the population. Sequence analysis at the population level and for individual clones revealed that in general, wild-type bases were preferred for positions −15 to +5 of the minimal promoter. Base mutagenesis experiments indicated that the selection of wild-type bases in this region was primarily due to requirements for subgenomic mRNA transcription. Outside of the minimal promoter, the −35 to −29 region contained four positions which also preferred wildtype bases. However, the remaining positions generally preferred non-wild-type bases. On passaging of the virus libraries on hamster cells, the −15 to +5 region again preferred the wild-type base but most of the remaining positions exhibited almost no base preference. The promoter thus consists of an essential central region from −15 to +5 and discrete flanking sites that render it fully active, depending on the host environment.
Human Cytomegalovirus US7, US8, US9, and US10 Are Cytoplasmic Glycoproteins, Not Found at Cell Surfaces, and US9 Does Not Mediate Cell-to-Cell Spread
Authors: Huber Mary T. , Tomazin Roman , Wisner Todd , Boname Jessica , Johnson David C.
Published: July 2002

Human cytomegalovirus (HCMV) expresses a large number of membrane proteins with unknown functions. One class of these membrane proteins apparently acts to allow HCMV to escape detection by the immune system. The best characterized of these are the glycoproteins encoded within the US2 to US11 region of the HCMV genome that mediate resistance to CD8
+
and CD4
+
T cells. US2, US3, US6, and US11 block various aspects of the major histocompatibility complex (MHC) class I and class II antigen presentation pathways, functioning in cytoplasmic membranes to cause retention, degradation, or mislocalization of MHC proteins. Distantly homologous genes in this region, US7, US8, US9, and US10, are not well characterized. Here, we report expression of the glycoproteins encoded by US7 to US10 by using replication-defective adenovirus (Ad) vectors. US7, US9, and US10 remained sensitive to endoglycosidase H and were exclusively or largely present in the endoplasmic reticulum (ER) as determined by confocal microscopy. US8 reached the Golgi apparatus and trans-Golgi network and was more quickly degraded. Previous studies suggested that US9 could localize to cell junctions and mediate cell-to-cell spread in ARPE-19 retinal epithelial cells. We found no evidence of US9 at cell junctions of HEC-1A epithelial cells. HCMV recombinants lacking US9 produced smaller plaques on ARPE-19 cell monolayers but also exhibited defects in virus replication compared with wild-type HCMV in these cells. Other HCMV recombinants constructed in a similar fashion that were able to express US9 also produced small plaques and some of these exhibited defects in production of infectious progeny in ARPE-19 cells. Thus, there was no correlation between defects in cell-to-cell spread (plaque size) and loss of expression of US9, and it is possible that US9
−
mutants produce smaller plaques because they produce fewer progeny. Together, our results do not support the hypothesis that US9 plays a direct role in HCMV cell-to-cell spread.
Antiviral Effects of Pyrrolidine Dithiocarbamate on Human Rhinoviruses
Authors: Gaudernak Elisabeth , Seipelt Joachim , Triendl Andrea , Grassauer Andreas , Kuechler Ernst
Published: July 2002

Human rhinoviruses (HRVs) are the predominant cause of the common cold. The frequency of HRV infections in industrial countries and the lack of effective therapeutical treatment underline the importance of research for new antiviral substances. As viral infections are often accompanied by the generation of oxidative stress inside the infected cells, several redox-active substances were tested as potential antivirals. In the course of these studies it was discovered that pyrrolidine dithiocarbamate (PDTC) is an extremely potent compound against HRV and poliovirus infection in cell culture. Besides the ability to dramatically reduce HRV production by interfering with viral protein expression, PDTC promotes cell survival and abolishes cytopathic effects in infected cells. PDTC also protects cells against poliovirus infection. These effects were highly specific, as several other antioxidants (vitamin C, Trolox, 2-mercaptoethanol, andN-acetyl-l-cysteine) are inactive against HRV infection. Synthesis of HRV proteins and cleavage of eucaryotic initiation factor 4G responsible for host cell shutoff of cellular protein synthesis are severely inhibited in the presence of PDTC.
Efficient Cleavage of Ribosome-Associated Poly(A)-Binding Protein by Enterovirus 3C Protease
Authors: Kuyumcu-Martinez N. Muge , Joachims Michelle , Lloyd Richard E.
Published: July 2002

Poliovirus (PV) causes a rapid and drastic inhibition of host cell cap-dependent protein synthesis during infection while preferentially allowing cap-independent translation of its own genomic RNA via an internal ribosome entry site element. Inhibition of cap-dependent translation is partly mediated by cleavage of an essential translation initiation factor, eIF4GI, during PV infection. In addition to cleavage of eIF4GI, cleavage of eIF4GII and poly(A)-binding protein (PABP) has been recently proposed to contribute to complete host translation shutoff; however, the relative importance of eIF4GII and PABP cleavage has not been determined. At times when cap-dependent translation is first blocked during infection, only 25 to 35% of the total cellular PABP is cleaved; therefore, we hypothesized that the pool of PABP associated with polysomes may be preferentially targeted by viral proteases. We have investigated what cleavage products of PABP are produced in vivo and the substrate determinants for cleavage of PABP by 2A protease (2A
pro
) or 3C protease (3C
pro
). Our results show that PABP in ribosome-enriched fractions is preferentially cleaved in vitro and in vivo compared to PABP in other fractions. Furthermore, we have identified four N-terminal PABP cleavage products produced during PV infection and have shown that viral 3C protease generates three of the four cleavage products. Also, 3C
pro
is more efficient in cleaving PABP in ribosome-enriched fractions than 2A
pro
in vitro. In addition, binding of PABP to poly(A) RNA stimulates 3C
pro
-mediated cleavage and inhibits 2A
pro
-mediated cleavage. These results suggest that 3C
pro
plays a major role in processing PABP during virus infection and that the interaction of PABP with translation initiation factors, ribosomes, or poly(A) RNA may promote its cleavage by viral 2A and 3C proteases.
Initial Interaction of Rotavirus Strains with
N
-Acetylneuraminic (Sialic) Acid Residues on the Cell Surface Correlates with VP4 Genotype, Not Species of Origin
Authors: Ciarlet Max , Ludert Juan E. , Iturriza-Gómara Miren , Liprandi Ferdinando , Gray James J. , Desselberger Ulrich , Estes Mary K.
Published: July 2002

We examined 41 human and animal rotavirus strains representative of all known P genotypes for their dependency on cellular
N
-acetylneuraminic (sialic) acid (SA) residues for infectivity. Our results showed that all rotaviruses studied, whether of animal or human origin, belonging to P genotypes [1], [2], [3], and [7] depended on SA residues on the cell surface for efficient infectivity but that all human and animal rotavirus strains representative of the remaining known P genotypes were SA independent. The SA residue requirement for efficient infectivity did not change for reassortant rotavirus strains with altered VP4-VP7 combinations. The initial interaction of rotavirus strains with SA residues on the cell surface correlated with VP4 genotype specifity, not with species of origin or VP7 G serotype specificity (
P
= 0.001;
r
2
= 1.00, Pearson's correlation coefficient). In addition to being a requirement for infectivity, the presence of SA residues on the cell surface is a requirement for efficient growth in cell culture; recognition of the association of specific P genotypes with the binding of rotavirus to SA residues will facilitate our understanding of the molecular basis of the early events of rotavirus-cell interactions in cell culture models and of pathogenicity in vivo.
Kinetics of Zinc(II) Reduction at the Hg Electrode in WaterEthanol Mixtures
Authors: Marczewska Barbara
Published: July 2002

The kinetics of the Zn(II)-Zn(Hg) electrode process was studied in water ethanol NaClO4 mixtures. Diffusion coefficients, formal potential and charge transfer rate constants were determined. The results are interpreted taking into account the change of the activation energy of the process.
Synthesis, Characterization and Crystal Structure of [Tetra-μ3-iodotetrakis{1'-(diphenylphosphino)ferrocenecarboxylic Acid-P}tetracopper(I)]-Acetic Acid (1 : 2)
Authors: Štěpnička Petr , Gyepes Róbert , Podlaha Jaroslav
Published: July 2002

The title compound was prepared by the reaction of 1'-(diphenylphosphino)ferrocenecarboxylic acid with copper(I) iodide in acetic acid. It has the tetrameric structure of the heterocubane type and all four monomeric units are crystallographically independent. The central Cu4I4 core is severely distorted from the Oh symmetry as a consequence of disparate radii of the atoms; however, this does not lead to transformation of the core into a stepped arrangement, the feature otherwise common for similar tetrameric structures. The ligand behaves as a monodentate phosphine and completes the approximately tetrahedral coordination polyhedron around copper(I). The carboxyl groups remain undissociated and uncoordinated but participate in intermolecular hydrogen bonding. Two carboxyl groups link the molecules of the tetramer into a zig-zag chain; the remaining two are bonded to molecules of solvating acetic acid which act as spacers between the chains. As expected, the geometry of the flexible ligand is remarkably influenced by the hydrogen bonding, the main conformation changes taking place at the P-C bonds and in the mutual arrangement of the cyclopentadienyl rings.
Towards Synthesis of Calysterols, Marine Sterols with Cyclopropene Moiety in the Side Chain: Synthesis of 26,27-Dinor-23H-isocalysterol
Authors: Kurek-Tyrlik Alicja , Minksztym Kazimierz , Wicha Jerzy
Published: July 2002

26,27-Dinor-23H-isocalysterol 24 has been synthesized in 19% yield (6 steps) from ethyl 6β-methoxy-3α,5-cyclo-5α-pregnan-21-oate (18). For construction of the side chain, alkylation of lithium salt of ester 18 with 1-bromo-1,2-dimethyl-c-3-iodomethyl-c-2-(trimethylsilyl)cyclopropane 16 was used. It has been shown that reduction of the ester group in position 21 and rearrangement of the 3,5-cyclosteroid system are compatible with the sidechain functionalities. It has been found that methylation of 1,1-dibromo-2-(trimethylsilyl)cyclopropane is accompanied by an rearrangement involving 1,2-migration of the trimethylsilyl group.
Possibilities of Decreasing Absorption of Water in Ion-Exchanger Catalysts
Authors: Jeřábek Karel , Prokop Zdeněk
Published: July 2002

Possibilities of decreasing the ability of strong-acid ion-exchanger catalysts to retain water were investigated in a case study of bisphenol A synthesis for to diminish effects of water as reaction product on the kinetics of the catalyzed reaction. It was found that partial thermal desulfonation or neutralization of about 30-40% acid groups with 2-aminoethanethiol can produce catalysts which exhibit, in the presence of technologically significant concentration of water, a higher activity in bisphenol A synthesis than conventional ion-exchanger catalysts.
Electrochemical Studies of the Stability of Copper β-Diketone Chelates
Authors: Mickler Wulfhard , Mönner Anke , Uhlemann Erhard
Published: July 2002

The voltammetric reduction of copper β-diketone chelates was used to get information on their complex stability. 1,1,1-Trifluoropentane-2,4-dione, pentane-2,4-dione, 1-phenylbutane-1,3-dione, 1,3-diphenylpropane-1,3-dione and 2,2,6,6-tetramethylheptane-3,5-dione were chosen as model ligands. The complexes were reduced in two separate steps the first of which proved to be reversible. The experimental data are suitable for calculation of the relative stability constants of corresponding Cu(I) and Cu(II) complexes. The data well correlate with the overall stability constants determined potentiometrically. The results were applied to some new hydrophobic β-diketones which are not accessible to potentiometric measurements.
Effect of Water Vapour on the Equilibrium Between CaO and COS in Coal Gas
Authors: Hartman Miloslav , Svoboda Karel , Trnka Otakar
Published: July 2002

The effectiveness of calcium oxide in the removal of carbonyl sulfide from coal gas is estimated by thermochemical computations. It is assumed that the gas phase composition is determined by the equilibria of the reactions of water vapour with calcium sulfide and carbonyl sulfide and by the water-gas-shift reaction. The proposed relationships can be employed in engineering considerations and calculations.
Voltammetric Study of N-Benzoylthiourea and Its N',N'-Disubstituted Derivatives as Possible Electrode Modifiers
Authors: Lubert Karl-Heinz , Beyer Lothar , Guttmann Markus
Published: July 2002

The voltammetric behavior of N-benzoylthiourea (BTU) and some of its N',N'-disubstituted derivatives is studied using glassy carbon and carbon paste electrodes in ethanolic solution. Irreversible reduction of the compounds takes place in a potential range between -0.5 and -1.1 V, where carbon surface groups are reduced as well. The products formed by reductive cleavage of the C-N bond of the amide group are oxidized in the subsequent positive scan at +0.5 V. Irreversible oxidation of the thiocarbonyl group of BTU (or its derivatives) takes place at about +1.0 V followed further by an oxidation of its N',N'-dialkyl and morpholine derivatives at more positive potentials. Oxidation current at +0.8 V is only observed in the case of the N',N'-diphenyl derivative. The oxidation current at +1.0 V depends linearly on the concentration of BTU (or its derivatives) and is suitable for their electroanalytical determination with carbon electrodes. The experimental results are compared with electrochemical behavior of related compounds. Furthermore, the influence of carbon surface states is discussed. It was concluded that N',N'-disubstituted derivatives of the BTU can be employed as modifying agents for carbon electrodes applicable in the potential range from +0.7 to -0.5 V.
Group 6 Metal Mixed Carbonyl Complexes with a Carboxyferrocenylphosphane
Authors: Lukešová Lenka , Ludvík Jiří , Císařová Ivana , Štěpnička Petr
Published: July 2002

A series of complexes [M(CO)5(Hdpf-κP)], where M = Cr (1), Mo (2) and W (3), and Hdpf is 1'-(diphenylphosphanyl)ferrocenecarboxylic acid, was obtained by thermally-induced (2) or photochemically-assisted (1, 3) displacement of carbon monoxide with Hdpf from the corresponding hexacarbonyl complexes. The complexes were characterized by NMR, UV-VIS and IR spectroscopies and further studied by cyclic voltammetry. The solid-state structure of complex 1 has been determined by single-crystal X-ray diffraction.
Choices without reasons: citizens' juries and policy evaluation
Authors: Price David
Published: July 2002

Citizens' juries are commended as a new technique for democratising health service reviews. Their usefulness is said to derive from a reliance on citizens' rational deliberation rather than on the immediate preferences of the consumer. The author questions the assertion of critical detachment and asks whether juries do in fact employ reason as a means of resolving fundamental disagreements about service provision. He shows that juries promote not so much a critically detached point of view as a particular evaluative framework suited to the bureaucratic idiom of social welfare maximisation. Reports of jury practice reveal a tendency among juries to suppress by non-rational means the everyday moral language of health care evaluation and substitute for it a system of thought in which it can be deemed permissible to deny treatment to sick people. The author concludes that juries are chiefly concerned with non-rational persuasion and because of this they are morally and democratically irrelevant. Juries are no substitute for voting when it comes to protecting the public from zealous minorities.
Vibration exposure, smoking, and vascular dysfunction
Authors: Cherniack Martin , Clive Jonathon , Seidner Adam
Published: July 2002

OBJECTIVES

Vibration white finger (VWF), also known as “occupational Raynaud's phenomenon”, is marked by arterial hyperresponsiveness and vasoconstriction during cold stimulation. The impact of tobacco use, and by extension stopping smoking, on the long term course of the disease has been inconclusively characterised. The objectives of this study included assessment of the impact of tobacco use on symptoms and on objective tests in shipyard workers exposed to vibration, and in gauging the natural history of the disorder after stopping exposure and changing smoking patterns.

METHODS

In a cross sectional investigation, 601 current and former users of pneumatic tools were evaluated subjectively for cold related vascular symptoms, and tested by cold challenge plethysmography. There was follow up and subsequent testing of 199 members of the severely effected subgroup of smokers and non-smokers, many of whom had stopped smoking in the interval between tests. Effects of smoking and stopping smoking on symptoms and plethsymographic results were assessed.

RESULTS

Symptoms and measured abnormal vascular responses related to cold were more severe in smokers than in non-smokers. Follow up of 199 severely effected members of the cohort, all removed from exposure for 2 years, indicated that smokers were almost twice as likely to have more severe vasospasm (test finger/control finger systolic blood pressure% (FSBP%) <30) than were non-smokers (−32.2%v17.4%). 53 Subjects who stopped smoking during the interval between tests improved, and were indistinguishable from non-smokers similarly exposed to vibration. Additional physiological benefits of stopping smoking were still apparent at further follow up examination, 1 year later. Improvements evident on plethysmography were not accompanied by improvements in symptoms, which were unaffected by smoking.

CONCLUSIONS

Smoking seems to delay physiological improvement in response to cold challenge in workers with VWF, after the end of exposure to vibration. Symptoms were less likely to improve over time than digital blood pressure, and were less affected by smoking.
Knowledge, attitude, practice, and toxicity symptoms associated with pesticide use among farm workers in the Gaza Strip
Authors: Yassin M M , Abu Mourad T A , Safi J M
Published: July 2002

Aims:To assess knowledge, attitude, practice, and toxicity symptoms associated with pesticide use and exposure among 189 farm workers in the Gaza Strip.

Methods:A cross section of agricultural farm workers in the Gaza Strip were asked to fill in a questionnaire on knowledge, attitudes, practice towards pesticide use, and associated toxicity symptoms.

Results:Farm workers reported high levels of knowledge on the health impact of pesticides (97.9%). Moderate to high levels of knowledge were recorded on toxicity symptoms related to pesticides. Most farm workers were aware of the protective measures to be used during applying pesticides. However, no one took precautions unless they knew about the measures. Burning sensation in eyes/face was the commonest symptom (64.3%). The prevalence of self reported toxicity symptoms was dependent on mixing and use of high concentrations of pesticides. The highest percentage of self reported toxicity symptoms was found among the farm workers who returned to sprayed fields within one hour of applying pesticides.

Conclusions:Farm workers in the Gaza Strip used pesticides extensively. Despite their knowledge about the adverse health impact of the pesticides, the use of protective measures was poor. Most had self reported toxicity symptoms, particularly the younger workers. It would be useful to minimise the use of pesticides and encourage alternative measures. Prevention and intervention programmes regarding the use of protective measures and monitoring the health status of farm workers should be implemented.
Fertilization dynamics in rainbow trout (Oncorhynchus mykiss): effect of male age, social experience, and sperm concentration and motility on in vitro fertilization
Authors: Liley N R , Tamkee P , Tsai R , Hoysak D J
Published: July 2002

We examine aspects of the fertilization dynamics of rainbow trout (Oncorhynchus mykiss) that may play a role in determining reproductive success of males of different age and status competing for spawning. There were no differences in the gonadosomatic indices and relative yields of milt of adult (3-year) and precocious (1-year) male rainbow trout collected from a wild population. The concentration of sperm in the milt of precocious males was higher than that of adult males. The duration of sperm motility was similar in the two groups of males and increased over the period of sampling. Interaction of a male with a nesting female caused an increase in milt yield, but did not affect sperm concentration, sperm motility, or fertilization rates. There was a sharp decline in fertilization rate 20 s or more after activation of the sperm or eggs by fresh water. Exposure to milt suspension for as little as 0.5 s resulted in fertilization of <27% of eggs. The short gamete longevity and the speed with which fertilization occurs indicate that the timing and position of sperm release may play a critical role in determining the reproductive success of males in competition for spawning with a single female.
An analytical approach towards determining the strength of FRP-reinforced/prestressed concrete beams
Authors: Salib Sameh R , Abdel-Sayed George , Grace Nabil
Published: July 2002

Non-corrosive fiber-reinforced polymers (FRP) are becoming a desirable replacement to steel bars in reinforcing/prestressing concrete structures. However, the difference between the two materials is not only related to the properties in the longitudinal direction of the bars as most of the current research work and design guidelines are concerned with. The properties in the transverse direction of the bars have basic differences, which may influence the beam strength and its mode of failure. This paper presents a comprehensive analytical modeling for evaluating the strength of concrete beams reinforced and (or) prestressed with FRP bars and the corresponding mode of failure. It takes into account significant parameters such as the crack path geometry, the crack width, and the properties of the bars in both longitudinal and transverse directions. The proposed analysis identifies any premature failure of beam due to the dowel failure of FRP reinforcement and determines the contribution of stirrups, if any, based on the number and actual tensile strain of the stirrups crossing the failure crack. A good agreement has been observed between the results of the developed model and the results of an experimental program conducted at the University of Windsor, as well as other published experimental programs.Key words: ACM, FRP, cracks, dowel action, reinforced concrete, strength.
Particle transport characteristics and filtration of granitic residual soils from the Korean peninsula
Authors: Lee I M , Park Y J , Reddi Lakshmi N
Published: July 2002

Weathered granitic residual soils, which are found in much of the Korean peninsula, pose unique challenges in terms of internal stability and filtration. The particle transport and filtration behavior of two extreme soil types, named Shinnae-dong and Poi-dong, are investigated in this paper. The erodibilities of the two soils are evaluated using constant flow-rate experiments on both undisturbed samples and samples with cylindrical holes. A comparison of the results from these experiments revealed the extent of particle redeposition and self-filtration in the internal erosion process. In spite of the differences in the mineralogical properties and engineering characteristics of the two soils, the size of the eroded particles from the two soils fell within the same range of 1100 µm. The two soils were coupled with filters, chosen according to the US Bureau of Reclamation's (USBR) filter criteria, to determine the efficiency of filters in minimizing erosion. It was found that the filters significantly minimized the erosion of the two base soils. However, the associated reductions in filter permeability are greater than one order of magnitude. Experiments using filters alone with particulate suspensions as the influents enabled the evaluation of a coefficient, λ, which could be used to characterize the particle retention capacities of the filters.Key words: particle transport, residual soils, filtration, drainage, Korean peninsula, soil filter criteria.
A facile methodology for the synthesis and detection of N7-guanine adduct of sulfur mustard as a biomarker
Authors: Rao Mula Kameswara , Bhadury Pinaki S , Sharma Mamta , Dangi Rajinder S , Bhaskar Appanabhotla S , Raza Syed K , Jaiswal Devendra K
Published: July 2002

A simple and convenient method has been developed for the synthesis of a N7-guanine adduct of sulfur mustard (SM), which can serve as an efficient biomarker for alleged exposure to SM. The adduct obtained in high yields (~78%) was characterized on the basis of its physical properties and spectral data. In addition, HPLC and LC-MS conditions have been standardized for the detection of the adduct in both in vitro and in vivo samples, which is useful for retrospective detection of exposure to SM in biological samples.Key words: sulfur mustard, biomarker, N7-guanine adduct, in vitro, in vivo, HPLC, LC-MS, electrospray, 2D NMR.
Fine-root decomposition and N dynamics in coniferous forests of the Pacific Northwest, U.S.A.
Authors: Chen Hua , Harmon Mark E , Sexton Jay , Fasth Becky
Published: July 2002

We examined the effects of species, initial substrate quality, and site differences (including temperature, precipitation, and soil N availability) on fine-root (<2 mm diameter) decomposition in litter bags and its N dynamics in Sitka spruce (Picea sitchensis (Bong) Carrière), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests in Oregon, U.S.A. Species significantly influenced fine-root mass loss during the first 2 years of decomposition. Over the same period, site differences had little impact on decomposition of fine roots. The percentage of initial mass remaining of decomposing fine roots fitted a single-exponential model. The decomposition rate constant (k) for all 15 species examined ranged from 0.172 year1 for Engelmann spruce (Picea engelmanni Parry ex Engelm.) to 0.386 year1 for Oregon ash (Fraxinus latifolia Benth.). Initial C quality indices (e.g., cellulose concentration, lignin concentration) of fine roots were correlated with fine-root decomposition rates. In contrast, initial N concentration and soil N availability were not correlated with fine-root decomposition rates. The rate of N released from decomposing roots was positively correlated with the initial N concentration of the fine roots. The data suggest that decomposing fine roots could release at least 20 kg N/ha annually in mature Douglas-fir forests of the Pacific Northwest.
Evaluation of mating dynamics in a lodgepole pine seed orchard using chloroplast DNA markers
Authors: Stoehr Michael U , Newton Craig H
Published: July 2002

Chloroplast DNA (cpDNA) markers were used to evaluate pollen dynamics in an operational lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard. High levels of cpDNA differentiation were obtained using six primer pairs specific to simple sequence repeat (SSR) and variable number tandem repeat (VNTR) loci dispersed around the lodgepole pine chloroplast genome. In 69 orchard parents genotypes, 46 multilocus haplotypes were detected with 31 of these being unique (i.e., having only one orchard parent). The number of variants (alleles) per locus ranged from two to seven with gene diversity levels of 0.44-0.72. Evaluation of wind-pollinated seedlots of 15 selected clones using these markers indicated low levels of selfing (2%) and pollen contamination (5%) but showed evidence of relatively high levels of differential male reproductive success.
NEW ANALYTIC RUNNING COUPLING IN QCD: HIGHER LOOP LEVELS
Authors: NESTERENKO A. V. , SOLOVTSOV I. L.
Published: July 2002

The properties of the new analytic running coupling are investigated at the higher loop levels. The expression for this invariant charge, independent of the normalization point, is obtained by invoking the asymptotic freedom condition. It is shown that at any loop level the relevant β-function has the universal behaviors at small and large values of the invariant charge. Due to this feature the new analytic running coupling possesses the universal asymptotics in both the ultraviolet and infrared regions irrespective of the loop level. The consistency of the model considered with the general definition of the QCD invariant charge is shown.
ELECTRON MASS OPERATOR IN A STRONG MAGNETIC FIELD
Authors: KUZNETSOV A. V. , MIKHEEV N. V. , OSIPOV M. V.
Published: July 2002

The electron mass operator in a strong magnetic field is calculated by summation of the leading log contributions in all orders of the perturbation theory. An influence of the strong field on the virtual photon polarization operator is taken into account. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation.
ALONGSIDE THE STANDARD MODEL: UNIFICATION VIA GEOMETRY
Authors: Avrin J. S.
Published: July 2002

A geometrical model (GM) featuring a visualizable reduction of the elementary particles and interactions down to common elements has been developed. As a consequence, a taxonomy of particles and various interactions emerge, all in consonance with the Standard Model (SM) of particle physics. However, the GM goes well beyond the SM, incorporating a number of fundamental phenomena and issues for which the latter has no explanation. Since the GMs largely diagramatic development cannot be displayed in this brief paper, only a summary of its conceptual basis and consequences is presented herein.
LIGHT-CONE FORM OF FIELD DYNAMICS IN AdS SPACE-TIME
Authors: METSAEV R. R.
Published: July 2002

Light-cone approach to field dynamics in AdS space-time is discussed.
PHASE LOCKING EFFECT OF PERSISTENT CURRENTS IN MESOSCOPIC ANDERSON–HUBBARD RINGS
Authors: TSOI F. Y. , LIANG SHI-DONG
Published: July 2002

The effects of the Anderson impurities as well as weak electron–electron interactions on the persistent current in a mesoscopic ring are studied by using the Anderson–Hubbard model. In this system, the single-particle energy spectrum possesses a flat b and and the s-d hybridization plays an interesting role in the phase dependence of the persistent current. In the weak s-d hybridization, the phases can be locked for different electron numbers. This phase locking effect originates from the existence of the flat band. In addition, it is found from the mean field approach that weak electron–electron interactions lead to the spin splitting of the energy b and and the shift of the electron number for the phase locking effect.
ARPES study of LSCO and PBCO: Electronic structure of the stripe phase and the 1/4-filled Cu-O chains
Authors: Mizokawa T. , Ino A. , Yoshida T. , Fujimori A. , Kim C. , Eisaki H. , Shen Z.-X. , Horii S. , Kakeshita T. , Uchida S. , Tomimoto K. , Tajima S. , Yamada Yuh
Published: July 2002

We have studied the electronic structure of the stripe phase in La 2-x Sr x CuO 4 (LSCO) and the Cu-O chains in PrBa 2 Cu 3 O 7 (Pr123) and PrBa 2 Cu 4 O 8 (Pr124) using angle-resolved photoemission spectroscopy (ARPES). In LSCO with x=0.12, the spectral feature near the Fermi level (EF) is almost flat from (π, 0) to (π, π/4), namely, along the stripe direction in LSCO. While the 1/4-filled chain in Pr123 has a band gap because of charge ordering, the metallic chain in Pr124 shows a dispersive feature which reaches EF at ~(π, π/4) and a flat feature near EF which is similar to that observed in the stripe phase of LSCO. Although Pr124 shows spectral-weight suppression near EF due to the instability toward charge ordering, the suppression is imperfect and Pr124 has a substantial spectral weight at EF probably due to the chain-chain coupling. This is in sharp contrast to LSCO with the perfect gap opening near (π, π/4). The difference between the stripe phase in LSCO and the coupled chains of Pr124 would be derived from the interaction between the stripe and the neighboring Cu spins which suppresses the charge ordering along the stripe.
MEAN FIELD, TWO-SITE CLUSTER, AND COMPUTER SIMULATION STUDY OF A NEMATOGENIC LATTICE-GAS MODEL
Authors: ROMANO S.
Published: July 2002

We have considered a classical lattice-gas model, consisting of a three-dimensional simple-cubic lattice, whose sites host three-component unit vectors; pairs of nearest-neighbouring sites interact via the nematogenic potential [Formula: see text] here P2(τ) denotes the second Legendre polynomial, νj = 0, 1 are occupation numbers, uj are unit vectors (classical spins), and ∊ is a positive quantity setting energy and temperature scales (i.e. T* = k B T/∊); the total Hamiltonian is given by [Formula: see text] where ∑{j<k} denotes sum over all distinct nearest-neighbouring pairs of lattice sites. The saturated-lattice version of this model defines the extensively studied Lebwohl–Lasher model, possessing a transition to an orientationally ordered phase at low temperature; according to available rigorous results, there exists a μ0 < 0, such that, for all μ > μ0, the system supports an ordering transition at a finite, μ-dependent, temperature. Continuing along the lines of our previous communication [S. Romano, Int. J. Mod. Phys.B14, 1195 (2000)], we present here a detailed study of the case μ = 0, using Monte Carlo simulation, Mean Field and Two Site Cluster treatments; the latter significantly improves the agreement with simulation results.
MULTILEVEL BLOCKING MONTE CARLO SIMULATIONS FOR QUANTUM DOTS
Authors: EGGER R. , MAK C. H.
Published: July 2002

This article provides an introduction to the ideas behind the multilevel blocking (MLB) approach to the fermion sign problem in path-integral Monte Carlo simulations, and also gives a detailed discussion of MLB results for quantum dots. MLB can turn the exponential severity of the sign problem into an algebraic one, thereby enabling numerically exact studies of otherwise inaccessible systems. Low-temperature simulation results for up to eight strongly correlated electrons in a parabolic 20 quantum dot are presented.
QUANTUM KINETIC THEORY FOR A BOSE-EINSTEIN CONDENSED ALKALI GAS
Authors: HOLLAND M. J. , COOPER J. , WALSER R.
Published: July 2002

The most salient features of the Bose-Einstein condensation of a magnetically confined alkali vapor is the diluteness of the gas and the extremely weak effective interactions. From a theoretical point of view, the interesting aspect is the potential formulation of the many-body quantum theory for a non-uniform and potentially non-equilibrium system founded entirely on microscopic physics. The crucial postulate is the rapid attenuation of many particle quantum correlations in the dilute system which can be motivated from universal considerations. In principle, it will be possible to provide direct comparison between theory and experiment over all temperature scales with no phenomenological parameters — a challenge facing the theoretical community in the near future. The dilute gas experiments provide an exciting stage on which to build bridges linking the theory of complex and collective phenomena in superconducting and superfluid systems, with the single particle microscopic physics described in quantum optics and laser physics.
INTERACTING ELECTRONS IN PARABOLIC QUANTUM DOTS: ENERGY LEVELS, ADDITION ENERGIES, AND CHARGE DISTRIBUTIONS
Authors: SCHREIBER MICHAEL , SIEWERT JENS , VOJTA THOMAS
Published: July 2002

We investigate the properties of interacting electrons in a parabolic confinement. To this end we numerically diagonalize the Hamiltonian using the Hartree-Fock based diagonalization method which is related to the configuration interaction approach. We study different types of interactions, Coulomb as well as short range. In addition to the ground state energy we calculate the spatial charge distribution and compare the results to those of the classical calculation. We find that a sufficiently strong screened Coulomb interaction produces energy level bunching for classical as well as for quantum-mechanical dots. Bunching in the quantum-mechanical system occurs due to an interplay of kinetic and interaction energy, moreover, it is observed well before reaching the limit of a Wigner crystal. It also turns out that the shell structure of classical and quantum mechanical spatial charge distributions is quite similar.
THEORETICAL STUDY ON THE PHOTOINDUCED DYNAMICS IN A MULTISTABLE ELECTRONIC SYSTEM
Authors: KOSHINO KAZUKI , OGAWA TETSUO
Published: July 2002

We theoretically discuss the photoinduced dynamics in multistable electronic systems, employing the photoinduced neutral-ionic (NI) transition in charge-transfer (CT) complexes as an example. On the NI transition temperature, a conventional picture of excitation in this material (CT exciton) does not hold; instead, the boundary between the two phases (NI domain wall) should be regarded as a basic excitation. After photoinjection of a microscopic ionic domain into the N phase, it grows into a large ionic domain through the band motion of NI domain waII. The domain extends at a constant speed, randomly choosing spins of transferred electrons.
METAL-OXYGEN-HYDROGEN SOLID SYSTEM OF CONTROLLED COMPOSITION: DIFFERENTIAL HEAT EFFECTS, KINETICS, AND MECHANISMS OF THE CuO → Cu4·OH2 GRADING
Authors: OSTROVSKII VICTORE E.
Published: July 2002

The process of fine-crystal CuO reduction by successive small portions of H 2 was studied through isothermal calorimetric, kinetic, adsorption-desorption, and stoichiometric measurements at 293-520 K and H 2 pressures up to 100 Pa under conditions when equilibrium within the solid was achieved at any instant. The CuO studied was in the form of the component of the CuO-ZnO-Al 2 O 3 system. The stoichiometry of the copper component reduced corresponded to Cu 4· OH 2.
A FED PROTOTYPE USING PATTERNED DLC THIN FILMS AS THE CATHODE
Authors: LI W. , FENG T. , MAO D. S. , WANG X. , LIU X. H. , ZOU S. C. , ZHU Y. K. , LI Q. , XU J. F. , JIN S. , ZHENG J. S.
Published: July 2002

In our study, diamond-like-carbon (DLC) thin films were prepared by filtered arc deposition (FAD), which provided a way to deposit DLC thin films on large areas at room temperature. Glass slides coated 100nm chromium or titanium thin films were used as cathode substrates. Millions of rectangular holes with sizes of 5 × 5μm were made on the DLC films using a routine patterning process. Here a special reactive ion beam etching method was applied to etch the DLC films. The anodes of the devices were made by electrophoretic deposition. ZnO:Zn phosphor (P15) was employed, which has a broad band bluish green (centered at 490nm). Before electrophoretic deposition, the anode substrates (ITO glass slides) had been patterned into 50 anode electrodes. In order to improve the adherence of phosphor layers, the as-deposited screens were treated in Na2SiO3 solution for 24h to add additional binder. A kind of matrix-addressed diode FED prototype was designed and packaged. 50-100μm-thick glass slides were used as spacers and getters were applied to maintain the vacuum after the exhaustion. The applied DC voltage was ranged in 0-3000V and much higher current density was measured in the cathode-patterned prototypes than the unpatterned ones during the test. As a result, characters could be well displayed.
GAUSSIAN ORTHOGONAL ENSEMBLE FOR THE LEVEL SPACING STATISTICS OF THE QUANTUM FOUR-STATE CHIRAL POTTS MODEL
Authors: ANGLÈS d'AURIAC J.-Ch. , DOMMANGE S. , MAILLLARD J.-M. , VIALLET C. M.
Published: July 2002

We have performed a Random Matrix Theory (RMT) analysis of the quantum four state chiral Potts chain for different sizes of the quantum chain up to eight sites, and for different unfolding methods. Our analysis shows that one generically has a Gaussian Orthogonal Ensemble statistics for the unfolded spectrum instead of the GUE statistics one could expect. Furthermore a change from the generic GOE distribution to a Poisson distribution occurs when the hamiltonian becomes integrable. Therefore, the RMT analysis can be seen as a detector of "higher genus integrability".