bluuebunny/crossref_metadata_2025 huggingface dataset:
Intra- and Intercellular Trafficking of the Foamy Virus Auxiliary Bet Protein
Authors: Lecellier Charles-Henri , Vermeulen Wim , Bachelerie Françoise , Giron Marie-Lou , Saïb Ali
Published: July 2002

The Bet protein of foamy viruses (FVs) is an auxiliary protein encoded by the 3′ end of the viral genome. Although its function during the viral replication cycle is still unknown, Bet seems to play a key role in the establishment and/or maintenance of viral persistence, representing the predominant viral protein detected during chronic infection. To clarify the function of this viral protein, the subcellular distribution of Bet from the prototypic human foamy virus (HFV) was examined. We report here that this protein is distributed in both the cytoplasm and the nucleus of HFV-infected or Bet-transfected cells. The nuclear targeting results from the presence of a bipartite nuclear localization signal at the C-terminal region, sufficient to direct heterologous reporter proteins to the nucleus. Since HFV Bet spreads between cells, we show here that the secreted protein targets the nuclei of recipient cells. HFV Bet follows an unconventional route to exit the cell since its secretion is not affected by brefeldin A, a drug which disrupts the trafficking between the endoplasmic reticulum and the Golgi complex. Finally, these inter- and intracellular movements were also observed for the equine foamy virus Bet protein, strongly suggesting that these remarkable features are conserved among FVs.
Exploiting the Natural Diversity in Adenovirus Tropism for Therapy and Prevention of Disease
Authors: Havenga M. J. E. , Lemckert A. A. C. , Ophorst O. J. A. E. , van Meijer M. , Germeraad W. T. V. , Grimbergen J. , van den Doel M. A. , Vogels R. , van Deutekom J. , Janson A. A. M. , de Bruijn J. D. , Uytdehaag F. , Quax P. H. A. , Logtenberg T. , Mehtali M. , Bout A.
Published: July 2002

Since targeting of recombinant adenovirus vectors to defined cell types in vivo is a major challenge in gene therapy and vaccinology, we explored the natural diversity in human adenovirus tissue tropism. Hereto, we constructed a library of Ad5 vectors carrying fibers from other human serotypes. From this library, we identified vectors that efficiently infect human cells that are important for diverse gene therapy approaches and for induction of immunity. For several medical applications (prenatal diagnosis, artificial bone, vaccination, and cardiovascular disease), we demonstrate the applicability of these novel vectors. In addition, screening cell types derived from different species revealed that cellular receptors for human subgroup B adenoviruses are not conserved between rodents and primates. These results provide a rationale for utilizing elements of human adenovirus serotypes to generate chimeric vectors that improve our knowledge concerning adenovirus biology and widen the therapeutic window for vaccination and many different gene transfer applications.
Nef-Mediated Downregulation of CD4 Enhances Human Immunodeficiency Virus Type 1 Replication in Primary T Lymphocytes
Authors: Lundquist Christopher A. , Tobiume Minoru , Zhou Jing , Unutmaz Derya , Aiken Christopher
Published: July 2002

The accessory protein Nef plays a crucial role in primate lentivirus pathogenesis. Nef enhances human immunodeficiency virus type 1 (HIV-1) infectivity in culture and stimulates viral replication in primary T cells. In this study, we investigated the relationship between HIV-1 replication efficiency in CD4
+
T cells purified from human blood and two various known activities of Nef, CD4 downregulation and single-cycle infectivity enhancement. Using a battery of reporter viruses containing point mutations in
nef
, we observed a strong genetic correlation between CD4 downregulation by Nef during acute HIV-1 infection of activated T cells and HIV-1 replication efficiency in T cells. In contrast, HIV-1 replication ability was not significantly correlated with the ability of Nef to enhance single-cycle virion infectivity, as determined by using viruses produced in cells lacking CD4. These results demonstrate that CD4 downregulation by Nef plays a crucial role in HIV-1 replication in activated T cells and underscore the potential for the development of therapies targeting this conserved activity of Nef.
Synthesis and Allylic Oxidation of 2,3-Dehydro-9β-benzoyloxy-β-agarofuran
Authors: Chen Xin , Nan Fajun , Xiong Zhaoming , Shao Sichang , Li Tongshuang , li Yulin
Published: July 2002

2,3-Dehydro-9β-benzoyloxy-β-agarofuran (VI), possible precursor of (+/-)-triptogelin G-2 (I), has been synthesized through a twelve-step procedure, allylic oxidation of which with various oxidative reagents has also been investigated, and three unusual oxidized products, ketoaldehyde X, peroxide XI, and ketone XII, were isolated.
Separation of Lead, Cadmium, and Iron in Analyses of Soil Samples
Authors: Svoboda Ladislav , Šafařík Tomáš , Schmidt Uwe
Published: July 2002

The conditions of sorption of chloride complexes of Pb2+, Cd2+, Fe2+, and Fe3+ ions from media of hydrochloric acid have been studied with a strongly basic anion exchanger - Ostion LG AT. The experiments used an exchanger microcolumn connected with atomic absorption spectrometer as a selective detector of metal ions. From the relation found between retention of the ions studied and hydrochloric acid concentration, conditions of separation have been suggested and used for separations of small amounts of lead and cadmium from many times higher amounts of iron and aluminium in soil extract before determination of both the foreign metals by means of AAS method. The yield of separation exceeded 95%.
Synthesis of New [1,3]Diazaheterocyclo[2',1':2,3][1,3,5]thiadiazino[4,5-f]purine Ring Systems
Authors: Hesek Dušan , Rybár Alfonz , Alföldi Juraj , Bella Juraj , Pätoprstý Vladimír
Published: July 2002

A simple method for preparation of the title ring systems 3a-3d starting from 7-chloromethyl-8-chloro-1,3-dimethyl-7H-purine-2,6(1H,3H)-dione (1) and cyclic isothioureas 2 is described. First, alkylation of the mercapto group of compound 2 took place to give 7-isothiuronium derivative 5, which in turn cyclized to the final product 3 in alkaline medium.
Study of Self Oscillatory Belousov-Zhabotinsky Systems Under the Perturbation of External EMF
Authors: Jayalakshmi Venkatanarayanan , Balasubramanian Natesan , Ramaswamy Renganathan
Published: July 2002

An examination of the current and potential oscillations in the self oscillatory Belousov-Zhabotinsky system under the application of external EMF is presented for the first time. The system involves Mn(II) as the metal ion catalyst and malic acid/citric acid/malonic acid as the substrate. External EMF shifts the oscillatory profile to the higher potential range by the magnitude of applied EMF. The amplitude of current oscillations increases with the magnitude of external EMF. The behaviour of the system with and without a complexing agent (tetrasodium pyrophosphate) is rationalised in terms of individual steps involved in the overall reaction.
Extraction of Tartaric Acid with Trialkylamine
Authors: Tomovska Radmila , Poposka Filimena , Volaufová Eva , Heyberger Aleš , Procházka Jaroslav
Published: July 2002

Extraction equilibria in the system aqueous solution of D-tartaric acid/solution of trialkylamine in binary diluent at 25 °C have been investigated. The amine used was a mixture of trialkylamines with C7-C9 alkyls, the diluent was a mixture hydrocarbon (n-heptane, kerosene) and a modifier (octan-1-ol, isodecanol, methyl isobutyl ketone). The effect of solvent composition on equilibrium was investigated and the experimental results were correlated using a mathematical model that takes into account chemical reactions involved in acid/amine complex formation, and the nonspecific effects of the nonideality of the system.
Accuracy Assessment of the ROHF-CCSD(T) Calculationsof Dipole Moments of Small Radicals
Authors: Urban Miroslav , Neogrády Pavel , Raab Juraj , Diercksen Geerd H. F.
Published: July 2002

Dipole moments of a series of radicals, OH, NO, NS, SF, SO, PO, ClO, CN, LiO, NO2, and ClO2 were calculated by the Coupled Cluster CCSD(T) method with the single determinant restricted open shell Hartree-Fock (ROHF) reference. For all molecules theoretical dipole moments were carefully compared to experimental values. The size and the quality of the basis set were systematically improved. Spin adaptation in the ROHF-CCSD(T) method, largest single and double excitation amplitudes and the T1 diagnostics were considered as indicators in the quality assessment of calculated dipole moments. For most molecules the accuracy within 0.01-0.03 D was readily obtained. For ClO and CN the spin adaptation was necessary - its contribution was as large as 0.03-0.045 D. Large deviation from experiment is observed for OH in its A2Σ+ excited state (0.135 D) and especially for LiO in its 2Π ground state (0.22 D). No indication of the failure of theoretical calculations was found which leads to the conclusion that, even if there is still a space for the improvement of theoretical calculations, experimental values should be reconsidered.
Partial Oxidation of Methane on Silica-Supported Vanadia Catalysts. The Relevance of Catalyst BET Area and Gas-Phase Activation
Authors: Cardoso José Hilton , Bañares Miguel A. , Bueno Jose M. Correa , Fierro Jose L. G.
Published: July 2002

Silica-supported vanadium oxide catalysts with different BET areas have been used in partial oxidation of methane to formaldehyde. The BET area of the silica support not only plays an important role in the activation of methane but also in promoting the degradation of reaction intermediates. A reaction scheme is proposed where HCHO and CO2 are primary products, whereas CO is a secondary product from the degradation of formaldehyde and hydrocarbons. A large BET area led to degradation of hydrocarbons to CO, whereas on low-BET-area catalysts, this side reaction is partially inhibited with the simultaneous formation of C2 hydrocarbons. The general trend observed is that the activity decreases with decreasing BET areas. Gas-phase reactivity increases the initial activation of methane, but does not increase the degradation of reaction intermediates as much as surface area does thus providing a selective activation for methane.
Quaternary Pyridinium Ketoximes - New Efficient Micellar Hydrolytic Catalysts
Authors: Cibulka Radek , Hampl František , Kotoučová Hana , Mazáč Jiří , Liška František
Published: July 2002

A series of quaternized alkyl pyridyl ketoximes was synthesized and tested as micellar hydrolytic catalysts. 2- And 4-[1-(hydroxyimino)tridecyl]-1-methylpyridinium bromides were surprisingly efficient, most probably due to the location of their nucleophilic hydroxyimino group below the micellar surface. Absorbance of the reaction mixture vs time plots exhibited remarkable positive deviation from the first-order kinetics when hydrolysis of 4-nitrophenyl phosphates was catalyzed by 1-dodecyl-3-[1-(hydroxyimino)ethyl]- or 3-[1-(hydroxyimino)tridecyl]-1-methylpyridinium bromide.
Electrochemical Reductions of Methyl Azinyl Ketoximes on Mercury
Authors: Cibulka Radek , Liška František , Ludvík Jiří
Published: July 2002

Electroreductions of hydroxyimino group of methyl hetaryl (pyridin-2-yl, pyridazin-3-yl, pyrimidin-2-yl, pyrimidin-4-yl, pyrazinyl) ketoximes on mercury electrodes were studied using dc polarography, coulometry and preparative electrolysis. Depending on pH, double- protonated, single-protonated and neutral forms of the ketoximes are transformed in a four-electron reduction to the corresponding amine. The second nitrogen in the diazine ketoximes facilitates reduction of the oxime group in comparison with methyl pyridin-2-yl ketoxime. Reducibility of the oximes correlates with the enhancement of their hydrolytic activity towards 4-nitrophenyl acetate. The reduction of the heteroaromatic ring in the diazine ketoximes proceeds at more negative potentials than the reduction of the oxime group.
Recurring Molecular Alignment Induced by Pulsed Nonresonant Laser Fields
Authors: Cai Long , Friedrich Břetislav
Published: July 2002

We examine the rotational wavepackets created by the nonadiabatic interaction of a linear molecule with a pulsed nonresonant laser field. We map out the recurrences of the wavepackets and of the concomitant alignment as a function of the duration and intensity of the laser pulse. We derive an analytic solution to the time-dependent Schrödinger equation in the short-pulse limit and find it to agree quantitatively with our numerical computations. This indicates that the recurrences are favored under an impulsive transfer of action from the radiative field to the molecule. The recurring wavepackets afford field-free alignment of the molecular axis.
Embolisation of a traumatic aneurysm of the posterior circumflex humeral artery in a volleyball player: Figure 1
Authors: Vlychou M , Spanomichos G , Chatziioannou A , Georganas M , Zavras G M
Published: July 2002

Repetitive minor vascular injuries caused by physical activity in athletes may lead to ischaemia of the upper extremities. In volleyball players in particular, traumatic aneurysm of the posterior circumflex humeral artery has been reported to be a cause of ischaemia of the arm and hand. Such an aneurysm is described here; it was treated successfully with endovascular embolisation.
Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence
Authors: Citarda F , Tomaselli G , Capocaccia R , Barcherini S , Crespi M , Group The Italian Multicentre Study
Published: July 2002

BACKGROUND

Colorectal cancer is one of the leading causes of death from cancer in Western countries. Removal of adenomas is based on the assumption that it could lead to a reduction in the incidence of colorectal cancer, as demonstrated by the National Polyp Study in the USA. A critical issue is whether the benefit observed in clinical trials can also be observed in standard clinical practice. To address the issue, a multicentre Italian collaborative study was organised.

METHODS

The study cohort comprised 1693 subjects of both sexes, aged 40–69 years, enrolled between 1980 and 1987 following a total colon examination (TCE) (that is, total colonoscopy or colonoscopy and double contrast barium enema), with removal of at least one adenoma larger than 5 mm in diameter. Exclusion criteria were genetic syndromes, previous adenomas or colorectal cancer, previous colonic resection, inflammatory bowel disease, or sessile adenomas more than 3 cm in diameter. Follow up ended in December 1996 by TCE or telephone interview, and review of the medical records, clinical files, or death certificates. Incidence ratios for colorectal cancer were compared with expected age and sex specific incidences in the Italian general population.

RESULTS

Follow up data were obtained for 97.3% of cases for a total of 14 211 person/years. Mean follow up was 10.5 years. Six colorectal cancer cases (four in males, two in females) at various stages were ascertained (one at 29 months, two at five years, one at seven years, one at eight years, and one at 10 years from the index examination). The number of cancers expected in the reference population was 17.7 for an incidence ratio of 0.34 (confidence interval 0.23–0.63; p<0.01).

CONCLUSIONS

Colonoscopic polypectomy substantially reduced the incidence of colorectal cancer in the cohort compared with that expected in the general population. These results are of particular relevance considering that those with adenomas are at increased risk of colorectal cancer and that this retrospective study was performed on data obtained in standard clinical practice. This observation strengthens the concept of effective population screening in view of the fact that adenomatous polyps are the most frequent neoplastic outcome of screening and their removal is associated with a decrease in the incidence of colorectal cancer.
The serodiagnosis of infection withSalmonella typhi
Authors: Chart H , Cheesbrough J S , Waghorn D J
Published: July 2002

Background/Aims—The serodiagnosis of infection withSalmonella typhi,using the Widal agglutination assay, relies on patients' antibodies to the O=9,12 lipopolysaccharide (LPS) antigens, H=d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection withS typhi.In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens.

Methods—The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation ofS typhi,ViI Bhatnagar variant strain (S typhi, ViI).Sera used in the study comprised 73 from patients who were culture positive forS typhi,10 from patients who were culture positive for other species ofSalmonellanot expressing a Vi antigen (namely,S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly,orS mbandaka), and eight from healthy blood donors.

Results—Agglutination titres of ≥ 1/40 were detected toS typhiViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies toS. typhiViI in all eight control sera and seven sera from patients infected withS bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley.

Conclusions—Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections withS typhishould be based on the detection of antibodies to both the O=9,12 LPS antigen and the H=d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid.
Occupational risk of Lyme disease: an epidemiological review
Authors: Piacentino J D , Schwartz B S
Published: July 2002

Lyme disease is the most common vector borne disease in the United States. Since the early 1980s, a large body of literature has evaluated the occupational risk of Lyme disease. The availability of a new vaccine to prevent Lyme disease makes it necessary for occupational health professionals to make decisions regarding the occupational risk of the disease among employees.
Epidemiological study to investigate potential interaction between physical and psychosocial factors at work that may increase the risk of symptoms of musculoskeletal disorder of the neck and upper limb
Authors: Devereux J J , Vlachonikolis I G , Buckle P W
Published: July 2002

Objectives: To investigate potential interactions between physical and psychosocial risk factors in the workplace that may be associated with symptoms of musculoskeletal disorder of the neck and upper limb.

Methods: 891 of 1514 manual handlers, delivery drivers, technicians, customer services computer operators, and general office staff reported on physical and psychosocial working conditions and symptoms of neck and upper limb disorders using a self administered questionnaire (59% return rate). Of the 869 valid questionnaire respondents, 564 workers were classified in to one of four exposure groups: high physical and high psychosocial, high physical and low psychosocial, low physical and high psychosocial, and low physical and low psychosocial. Low physical and low psychosocial was used as an internal reference group. The exposure criteria were derived from the existing epidemiological literature and models for physical and psychosocial work factors. The frequency and amplitude of lifting and the duration spent sitting while experiencing vibration were used as physical exposure criteria. Ordinal values of mental demands, job control, and social support with managers and coworkers were used as psychosocial exposure criteria.

Results: In the multivariate analyses, the highest and significant increase in risk was found in the high physical and high psychosocial exposure group for symptoms of hand or wrist and upper limb disorders after adjusting for years at the job, age, and sex. A potential interaction effect was found for the symptoms of the hand or wrist and upper limb disorders but not for the neck symptoms.

Conclusion: This study showed that workers highly exposed to both physical and psychosocial workplace risk factors were more likely to report symptoms of musculoskeletal disorders than workers highly exposed to one or the other. The results suggest an interaction between physical and psychosocial risk factors in the workplace that increased the risk of reporting symptoms in the upper limbs. Psychosocial risk factors at work were more important when exposure to physical risk factors at work were high than when physical exposure was low. Ergonomic intervention strategies that aim to minimise the risks of work related musculoskeletal disorders of the upper limb should not only focus on physical work factors but also psychosocial work factors.
Ecological restoration of land with particular reference to the mining of metals and industrial minerals: A review of theory and practice
Authors: Cooke J A , Johnson M S
Published: July 2002

Mining causes the destruction of natural ecosystems through removal of soil and vegetation and burial beneath waste disposal sites. The restoration of mined land in practice can largely be considered as ecosystem reconstruction  the reestablishment of the capability of the land to capture and retain fundamental resources. In restoration planning, it is imperative that goals, objectives, and success criteria are clearly established to allow the restoration to be undertaken in a systematic way, while realizing that these may require some modification later in light of the direction of the restoration succession. A restoration planning model is presented where the presence or absence of topsoil conserved on the site has been given the status of the primary practical issue for consideration in ecological restoration in mining. Examples and case studies are used to explore the important problems and solutions in the practice of restoration in the mining of metals and minerals. Even though ecological theory lacks general laws with universal applicability at the ecosystem level of organization, ecological knowledge does have high heuristic power and applicability to site-specific ecological restoration goals. However, monitoring and management are essential, as the uncertainties in restoration planning can never be overcome. The concept of adaptive management and the notion that a restored site be regarded as a long-term experiment is a sensible perspective. Unfortunately, in practice, the lack of post-restoration monitoring and research has meant few opportunities to improve the theory and practice of ecological restoration in mining. Key words: restoration, rehabilitation, revegetation, mining, succession, ecological theory.
Do abiotic mechanisms determine interannual variability in length-at-age of juvenile Arcto-Norwegian cod?
Authors: Ottersen Geir , Helle Kristin , Bogstad Bjarte
Published: July 2002

For the large Arcto-Norwegian stock of cod (Gadus morhua L.) in the Barents Sea, year-to-year variability in growth is well documented. Here three hypotheses for the observed inverse relation between abundance and the mean length-at-age of juveniles (ages 14) are suggested and evaluated. Based on comprehensive data, we conclude that year-to-year differences in length-at-age are mainly determined by density-independent mechanisms during the pelagic first half year of the fishes' life. Enhanced inflow from the southwest leads to an abundant cohort at the 0-group stage being distributed farther east into colder water masses, causing lower postsettlement growth rates. We can not reject density-dependent growth effects related to variability in food rations, but our data do not suggest this to be the main mechanism. Another hypothesis suggests that lower growth rates during periods of high abundance are a result of density-dependent mechanisms causing the geographic range of juveniles to extend eastwards into colder water masses. This is rejected mainly because year-to-year differences in mean length are established by age 2, which is too early for movements over large distances.
Determination of relative survival of two stocked walleye populations and resident natural-origin fish by microsatellite DNA parentage assignment
Authors: Eldridge William H , Bacigalupi Marc D , Adelman Ira R , Miller Loren M , Kapuscinski Anne R
Published: July 2002

Walleye (Stizostedion vitreum) from two northern Minnesota spawning stations (Pike River, Hudson Bay drainage, and Little Cutfoot Sioux Lake, Mississippi River drainage) simultaneously stocked as fry into five southern Minnesota lakes had different survival rates. One year after stocking, Pike River walleye were more abundant than their original proportion of 46.5% of the stocked fish, but by the end of their second summer, neither population had a clear survival advantage. In the three lakes where walleye were consistently sampled, natural-origin walleye that descended from previous stockings significantly increased in percent of all sampled walleye over the study (P = 0.001). The unmarked and untagged stocked fish (N = 566) were assigned to their source population by comparing their genotypes at nine microsatellite DNA loci to the known genotypes of the parent pairs crossed in a hatchery (parentage assignment). Fish not assigned to a parent pair were considered to be the product of natural reproduction (N = 177) by previously stocked fish. Simulations indicated that natural-origin walleye were sufficiently excluded from assignment to stocked fish parent pairs so as not to bias the comparison. Parentage assignment is a powerful population discrimination tool if genotypes are known for all parent pairs from all but one putative source.
Risk analysis in environmental systems
Authors: Shakshuki Elhadi , Ponnambalam Kumaraswamy , Wodaj Tassew
Published: July 2002

Uncertainty is an inherent feature of environmental systems, which makes probabilistic models important. Environmental risk assessment is an important but time consuming task. For large-scale systems, use of linear systems with uncertainty information on parameters and inputs is one of the few possible methods to assess risk. To estimate risk, it is necessary to have at least the first two moments of output variables. This paper describes an efficient method developed for second-moment analysis of linear systems with uncertain coefficients. The main objective is to provide the means and the variances of the output and to provide efficient formulation and automation of the moment equations. This method is demonstrated in two real-world applications of environmental modeling.Key words: uncertainty, second-moment methods, risk analysis, reliability, linear systems.
Field and material-specific simulated distribution system testing as aids to understanding trihalomethane formation in distribution systems
Authors: Brereton J A , Mavinic D S
Published: July 2002

The evolution of disinfection by-products (DBP) in drinking water is triggered at the initial point of disinfectant application and, in most cases, continues to some extent throughout the distribution system. A comprehensive study using an extensive field monitoring program, together with an improved simulated distribution system (SDS) test, is presented, in which the effects of increased chlorine demand exerted by internal pipe walls are included in the evaluation of potential DBP exposure to the public. In the field study, comparing both pre-formed trihalomethane (THM) and THM formation potential among several distribution system locations eliminated inherent uncertainties associated with the complexities of network hydraulics, leaving exposure to the internal pipe environment as the primary factor of interest. Findings in this paper confirm the reliability of using the material-specific SDS (MS-SDS) test as a better representation of DBP evolution in a real distribution system. In the case study, the increased chlorine demand of unlined cast-iron results in lower levels of trihalomethanes than those dictated by testing the finished water alone. The MS-SDS test is readily adaptable for pilot-plant studies where real distribution system conditions are inaccessible.Key words: chloroform, disinfection by-products, distribution systems, field monitoring, simulated distribution system.
Friction velocity and power law velocity profile in smooth and rough shallow open channel flows
Authors: Balachandar R , Blakely D , Bugg J
Published: July 2002

This paper examines the mean velocity profiles in shallow, turbulent open channel flows. Velocity measurements were carried out in flows over smooth and rough beds using a laser-Doppler anemometer. One set of profiles, composed of 29 velocity distributions, was obtained in flows over a polished smooth aluminum plate. Three sets of profiles were obtained in flows over rough surfaces. The rough surfaces were formed by two sizes of sand grains and a wire mesh. The flow conditions over the rough surface are in the transitional roughness state. The measurements were obtained along the centerline of the flume at three different Froude numbers (Fr ~ 0.3, 0.8, 1.0). The lowest Froude number was selected to obtain data in the range of most other open channel testing programs and to represent a low subcritical Froude number. For each surface, the Reynolds number based on the boundary layer momentum thickness was varied from about 600 to 3000. In view of the recent questions concerning the applicability of the log-law and the debate regarding log-law versus power law, the turbulent inner region of the boundary layer is inspected. The fit of one type of power law for shallow flows over a smooth surface is considered. The appropriateness of extending this law to flows over rough surfaces is also examined. Alternate methods for determining the friction velocity of flows over smooth and rough surfaces are considered and compared with standard methods currently in use.Key words: power law, open channel flow, velocity profile, surface roughness.
Lactoferrin-binding proteins inBifidobacterium bifidum
Authors: Kim Woan-Sub , Tanaka Tetsuya , Kumura Haruto , Shimazaki Kei-ichi
Published: July 2002

Lactoferrin is an iron-binding glycoprotein and its bacteriostatic and bactericidal effects on gram-positive and gram-negative bacteria are well known. On the other hand, it is known that certain kinds of lactic acid bacteria are resistant to its antibacterial effects. Moreover, it is reported that lactoferrin promotes the growth of bifidobacteria in in vitro and in vivo experiments. In our experiments, lactoferrin-binding protein was found both in the membrane and cytosolic fractions of Bifidobacterium bifidum Bb-11. The bifidobacteria were grown in anaerobic conditions with lactobacilli MRS broth containing cysteine, harvested by centrifugation, and processed by sonication. The lactoferrin-binding proteins on the PVDF-membrane transferred after SDS-PAGE were detected by far-Western (western-Western) method using biotinylated lactoferrin and streptavidin-labelled horse radish peroxidase. The molecular weights of the lactoferrin binding protein detected in the membrane fraction were estimated to be 69 kDa and those in cytosolic fractions were 20, 35, 50, and 66 kDa.Key words: lactoferrin, Bifidobacterium, lactic acid bacteria, binding protein.
Pathogens and insects in a pristine forest ecosystem: the Sierra San Pedro Martir, Baja, Mexico
Authors: Maloney Patricia E , Rizzo David M
Published: July 2002

We determined the incidence of pathogens and insects across mixed-conifer stands in the Sierra San Pedro Martir (SSPM) of northern Baja, Mexico, to assess the role of pests in a pristine forest ecosystem. We also determined the spatial distribution of the two most common pests, mistletoe, Phoradendron pauciflorum Torrey, and the fir engraver, Scolytus ventralis LeConte, of white fir (Abies concolor (Gord. & Glend.) Lindl.) across a 25-ha grid to assess spread and what host and pest variables were related. In these open parklike stands the mean tree density was 160 trees/ha, of which 58% were trees >20 cm diameter at breast height (DBH). In these low-density, mixed-aged stands we found that mixed-conifer species were well represented with no one species being completely dominant. Percent cumulative mortality for the SSPM was 12.7%, ranging from 2 to 24%, with the greatest amount of mortality occurring in the larger size classes, trees [Formula: see text]50 cm DBH. Multiple linear regression analysis showed that 78% of the mortality we observed was explained by pathogens and bark beetles (r2 = 0.78, P = 0.0001, F = 84). Mean pest incidence for Jeffrey pine (Pinus jeffreyi Grev. & Balf. in A. Murray), white fir, and sugar pine (Pinus lambertiana Dougl.) was 21, 88, and 2%, respectively. We found a number of relationships among host and pest variables, as well as a pathogen insect interaction, and across the SSPM we found that nonhost species may be interfering in certain hostpest interactions. Spatial patterns from the 25-ha grid survey revealed that both P. pauciflorum and S. ventralis incidence were widespread. Phoradendron pauciflorum showed no spatial structure across the 25 ha but S. ventralis showed some degree of spatial structuring across the survey area. We also found that mistletoe severity was negatively correlated with regeneration of white fir. In pristine forests, pathogens and insects influence mortality and regeneration success, affecting stand structure and composition.
RESOURCE ESTIMATION ALGORITHM UNDER IMPRECISENESS USING INCLUSION SCHEDULING
Authors: CHANTRAPORNCHAI CHANTANA , TONGSIMA SISSADES
Published: July 2002

In this paper, we propose a resource estimation algorithm which considers imprecise system characteristics and multiple design attributes. The algorithm is based on a polynomial-time process called inclusion scheduling. Inclusion scheduling takes imprecise system information and generates an averagely good schedule with respect to a design goal. The schedule is associated with various properties. These information are used to determine the initial resource bounds subject to the design goal. Experimental results showing the effectiveness of the approach by comparing the design configuration generated by the traditional algorithm and the approach are presented.
ON DYNAMIC TASK SCHEDULING FOR FPGA-BASED SYSTEMS
Authors: DIESSEL OLIVER , ELGINDY HOSSAM
Published: July 2002

The development of FPGAs that can be programmed to implement custom circuits by modifying memory has inspired researchers to investigate how FPGAs can be used as a computational resource in systems designed for high performance applications. When such FPGA–based systems are composed of arrays of chips or chips that can be partially reconfigured, the programmable array space can be partitioned among several concurrently executing tasks. If partition sizes are adapted to the needs of tasks, then array resources become fragmented as tasks with varying requirements are processed. Tasks may end up waiting despite their being sufficient, albeit fragmented resources available. We examine the problem of repartitioning the system (rearranging a subset of the executing tasks) at run–time in order to allow waiting tasks to enter the system sooner. In this paper, we introduce the problems of identifying and scheduling feasible task rearrangements when tasks are moved by reloading. It is shown that both problems are NP–complete. We develop two very different heuristic approaches to finding and scheduling suitable rearrangements. The first method, known as Local Repacking, attempts to minimize the size of the subarray needing rearrangement. Candidate subarrays are repacked using known bin packing algorithms. Task movements are scheduled so as to minimize delays to their execution. The second approach, called Ordered Compaction, constrains the movements of tasks in order to efficiently identify and schedule feasible rearrangements. The heuristics are compared by time complexity and resulting system performance on simulated task sets. The results indicate that considerable scheduling advantages are to be gained for acceptable computational effort. However, the benefits may be jeopardized by delays to moving tasks when the average cost of reloading tasks becomes significant relative to task service periods. We indicate directions for future research to mitigate the cost of moving executing tasks.
A UNIFIED APPROACH TO RESOLVENT EXPANSIONS AT THRESHOLDS
Authors: JENSEN ARNE , NENCIU GHEORGHE
Published: July 2002

Results are obtained on resolvent expansions around zero energy for Schrödinger operators H=-Δ+V(x) on L2(Rm), where V(x) is a sufficiently rapidly decaying real potential. The emphasis is on a unified approach, valid in all dimensions, which does not require one to distinguish between ∫V(x)dx=0 and ∫V(x)dx≠0 in dimensions m=1,2. It is based on a factorization technique and repeated decomposition of the Lippmann–Schwinger operator. Complete results are given in dimensions m=1 and m=2.
EVOLUTION OF CENTRAL MOMENTS FOR A GENERAL-RELATIVISTIC BOLTZMANN EQUATION: THE CLOSURE BY ENTROPY MAXIMIZATION
Authors: BANACH ZBIGNIEW , LARECKI WIESLAW
Published: July 2002

Beginning from the relativistic Boltzmann equation in a curved space-time, and assuming that there exists a fiducial congruence of timelike world lines with four-velocity vector field u, it is the aim of this paper to present a systematic derivation of a hierarchy of closed systems of moment equations. These systems are found by using the closure by entropy maximization. Our concepts are primarily applied to the formalism of central moments because if an alternative and more familiar theory of covariant moments is taken into account, then the method of maximum entropy is ill-defined in a neighborhood of equilibrium states. The central moments are not covariant in the following sense: two observers looking at the same relativistic gas will, in general, extract two different sets of central moments, not related to each other by a tensorial linear transformation. After a brief review of the formalism of trace-free symmetric spacelike tensors, the differential equations for irreducible central moments are obtained and compared with those of Ellis et al. [Ann. Phys. (NY)150 (1983) 455]. We derive some auxiliary algebraic identities which involve the set of central moments and the corresponding set of Lagrange multipliers; these identities enable us to show that there is an additional balance law interpreted as the equation of balance of entropy. The above results are valid for an arbitrary choice of the Lorentzian metric g and the four-velocity vector field u. Later, the definition of u as in the well-known theory of Arnowitt, Deser, and Misner is proposed in order to construct a hierarchy of symmetric hyperbolic systems of field equations. Also, the Eckart and Landau–Lifshitz definitions of u are discussed. Specifically, it is demonstrated that they lead, in general, to the systems of nonconservative equations.
TYPE OF 3-MANIFOLDS AND ADDITION OF RELATIVISTIC KINKS
Authors: SHASTRI A. R. , ZVENGROWSKI P.
Published: July 2002

The type of a closed, connected, orientable 3-manifold M was first considered in the classification of relativistic kinks over the space-time 4-manifold M × R. In this paper theorems are developed relating the type of M to H1 (M; Z), which lead to the determination of the type of large families of 3-manifolds. The relation of type to connected sum is established, and the connected sum is also used to define addition of kinks. The kink addition is related to the sum of the kink numbers, as well as addition in the bordism group Ω3(P3).
SEMI-CLASSICAL ANALYSIS FOR TOTAL CROSS-SECTIONS OF MAGNETIC SCHRÖDINGER OPERATORS IN TWO DIMENSIONS
Authors: TAMURA HIDEO
Published: July 2002

We define total scattering cross-sections for magnetic Schrödinger operators in two dimensions and prove the shadow scattering (the quantum total cross-sections double the classical ones in the semi-classical limit) under some assumptions.
RIGOROUS RESULTS FOR THE GINZBURG-LANDAU EQUATIONS ASSOCIATED TO A SUPERCONDUCTING FILM IN THE WEAK κ LIMIT
Authors: BOLLEY CATHERINE , HELFFER BERNARD
Published: July 2002

In continuation with our preceding paper [10] concerning the superconducting film, we present in this article rigorous results concerning the superheating in the weak κ limit. The principal result is an important step toward the rigorous proof of a formula due to P. De Gennes [26] . This paper is complementary to our paper [11] where numerical results are presented and approximate models are discussed. Most of the results have been announced in [12] and [13].
A DETAILED ACCOUNT OF ALAIN CONNES’ VERSION OF THE STANDARD MODEL IV
Authors: KASTLER DANIEL , SCHÜCKER THOMAS
Published: July 2002

We give a detailed account of the computation of the Yang-Mills action for the Connes-Lott model with general coupling constant in the commutant of the K-cycle. This leads to tree-approximation results amazingly compatible with experiment, yielding a first indication on the Higgs mass.
Some Mathematical Problems Related to Classical-Quantum Interactions
Authors: Olkiewicz R.
Published: July 2002

A mathematical model describing the interaction between classical and quantum systems is proposed. The discrete case of a counter as well as the continuous case of the SQUID-tank model are discussed.
SU(n)-CHERN–SIMONS INVARIANTS OF SEIFERT FIBERED 3-MANIFOLDS
Authors: NISHI HARUKO
Published: July 2002

We derive the formula for the Chern–Simons invariants of irrreducible SU(n)-flat connections on the Seifert fibered 3-manifolds. As an example, we calculate the values explicitly for the Seifert fibered 3-manifold S3/Γ, where Γ is a finite subgroup of SU(2).
GENERALIZED OPTIMAL VELOCITY MODEL FOR TRAFFIC FLOW
Authors: SAWADA SHIRO
Published: July 2002

A generalized optimal velocity model is analyzed, where the optimal velocity function depends not only on the headway of each car but also the headway of the immediately preceding one. The stability condition of the model is derived by considering a small perturbation around the homogeneous flow solution. The effect of the generalized optimal velocity function is also confirmed with numerical simulations, by examining the hysteresis loop in the headway-velocity phase space, and the relation between the flow and density of cars. In the model with a specific parameter choice, it is found that an intermediate state appears for the movement of cars, where the car keeps a certain velocity whether the headway is short or long. This phenomenon is different from the ordinary stop-and-go state.
LEADER-BASED CONSENSUS
Authors: MOSTEFAOUI A. , RAYNAL M.
Published: July 2002

It is now well recognized that consensus is a fundamental problem one has to solve to implement reliable applications on top of unreliable asynchronous distributed systems prone to failures. It has been shown that this problem cannot be solved if the underlying asynchronous system does not satisfy additional assumptions. This paper presents a new consensus protocol based on a leader oracle (denoted Ω in the litterature). Although this protocol uses asynchronous rounds, it is not based on the rotating coordinator paradigm. As a consequence, it does not suffer from drawbacks inherent to ♢S-based consensus protocols that explicity use this paradigm. As Ω and ♢S are equivalent, the proposed protocol does not require assumptions stronger or weaker than the ones abstracted in ♢S. Hence, it also requires f < n/2 (where n is the number of processes and f an upper bound on the number of processes that may crash). From a design point of view, the proposed protocol is surprisingly simple. From an efficiency point of view, it allows the processes to agree in a single round when the oracle provides the processes with the same leader (a common case in practice). It is also shown that the time and message costs of the protocol can be reduced when f < n/3. Moreover, when, in addition to the leader oracle, the system is equipped with a random oracle, the proposed protocol can be extended to provide a hybrid consensus protocol at no additional message cost.
$\Lambda_{\lc{b}}\rightarrow
\Lambda+D^0(\bar D^0)$ DECAYS AND CP-VIOLATION
Authors: FAYYAZUDDIN
Published: July 2002

It is shown that interference of the amplitudes for the decays Λb→ΛD and [Formula: see text] gives rise to CP-violation.
THE HIGH ENERGY EMISSION MORPHOLOGIES AND PHASE-RESOLVED SPECTRA OF PULSARS
Authors: CHENG K. S. , KO S. F. , LIE H. Y. , ZHANG L.
Published: July 2002

There has been much progress in detecting and understanding high-energy (~1 keV–10 GeV) radiation from rotation powered pulsars. Strong evidence indicates that the nonthermal radiation is emitted from the outer magnetosphere. The local properties in the magnetosphere, e.g. retarded relativistic effect, the strength of the magnetic field, radius of curvature, soft photon density, time of flight for photons etc., make the observed light curves and spectra of high energy radiation from pulsars not only depend on pulsar parameters, i.e. the stellar rotation period and the dipole magnetic field, but also depend on the inclination angle and the view angle. Three-dimensional outer magnetospheric models must be used to understand the complicated observed high energy emission morphologies and phase-dependent spectra of pulsars. Some basic properties of pulsars, recent observed results and other pulsar related phenomena are also reviewed.
GENERALIZED GAUGE THEORIES AND THE WEINBERG–SALAM MODEL WITH DIRAC–KÄHLER FERMIONS
Authors: KAWAMOTO NOBORU , UMETSU HIROSHI , TSUKIOKA TAKUYA
Published: July 2002

We extend the previously proposed generalized gauge theory formulation of the Chern–Simons type and topological Yang–Mills type actions into Yang–Mills type actions. We formulate gauge fields and Dirac–Kähler matter fermions by all degrees of differential forms. The simplest version of the model which includes only zero and one-form gauge fields accommodated with the graded Lie algebra of SU (2|1) supergroup leads the Weinberg–Salam model. Thus the Weinberg–Salam model formulated by noncommutative geometry is a particular example of the present formulation.
PERFORMANCE STUDIES OF THE DØ PRESHOWER DETECTOR
Authors: HOU S.
Published: July 2002

The DØ preshower detector has been tested with cosmic ray muons. We report results on the light yields for minimum ionizing particles and the spatial resolution. The detection efficiency and noise contamination are also investigated.
HEAVY FLAVOUR PHYSICS AT HERA — A SURVEY
Authors: BUSSEY P. J.
Published: July 2002

At the HERA collider at DESY, high energy electron and positron beams interact with proton beams. A review is presented of the variety of ways in which these collisions produce final states containing charm and beauty quarks.
ON THE $\bar{d}/\bar{u}$ ASYMMETRY AND PARTON DISTRIBUTIONS
Authors: DALEO ALEJANDRO , GARCIA CANAL CARLOS A. , NAVARRO GABRIELA A. , SASSOT RODOLFO
Published: July 2002

We discuss the impact of different measurements of the [Formula: see text] asymmetry in the extraction of parametrizations of parton distribution functions.
THE VIRTUAL BLACK HOLE IN 2D QUANTUM GRAVITY AND ITS RELEVANCE FOR THE S-MATRIX
Authors: GRUMILLER DANIEL
Published: July 2002

As shown recently 2d quantum gravity theories — including spherically reduced Einstein-gravity — after an exact path integral of its geometric part can be treated perturbatively in the loops of (scalar) matter. Obviously the classical mechanism of black hole formation should be contained in the tree approximation of the theory. This is shown to be the case for the scattering of two scalars through an intermediate state which by its effective black hole mass is identified as a "virtual black hole". We discuss the lowest order tree vertex for minimally and non-minimally coupled scalars and find a non-trivial finite S-matrix for gravitational s-wave scattering in the latter case.