bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maxwell–Chern–Simons Q-balls
Authors: Deshaies-Jacques M , MacKenzie R 
Published: July 2007

We examine the energetics of Q-balls in Maxwell–Chern–Simons theory in two space dimensions. Whereas gauged Q-balls are unallowed in this dimension in the absence of a Chern–Simons term due to a divergent electromagnetic energy, the addition of a Chern–Simons term introduces a gauge-field mass and renders finite the otherwise-divergent electromagnetic energy of the Q-ball. Similar to the case of gauged Q-balls , Maxwell–Chern–Simons Q-balls have a maximal charge. The properties of these solitons are studied as a function of the parameters of the model considered, using a numerical technique known as relaxation. The results are compared to expectations based on qualitative arguments. PACS Nos.: 11.10.Lm, 11.10.–z, 11.15.Kc
Is there new physics in B decays?
Authors: Datta A 
Published: July 2007

Rare decays of the B meson are sensitive to new physics effects. Several experimental results on these decays have been difficult to understand within the Standard Model (SM) though more precise measurements and a better understanding of SM theory predictions are needed before any firm conclusions can be drawn. In this note we try to understand the present data assuming the presence of new physics. We find that the data points to new physics of an extended Higgs sector and we present a two-Higgs-doublet model with a 2–3 flavor symmetry in the down-type quark sector that can explain the deviations from the Standard Model reported in several rare B decays. PACS Nos.: 11.30.Er, 11.30.Hv, and 13.20.He
Convergence issues in baryon chiral perturbation theory for the reaction π + N → 2π + N
Authors: Mobed N , Zhang J , Singh D 
Published: July 2007

We study the reaction π + N → 2π + N within the framework of heavy-baryon chiral perturbation theory of chiral order three. We find that contributions from amplitudes of chiral order three are large and play an essential role in reproducing the experimental data. In addition, we evaluate a polarization observable (target asymmetry) for the transverse polarization of the proton target and find that the asymmetry is generally small for the reaction under consideration. PACS Nos.: 25.80.Hp, 13.75.Gx, 11.30.Rd, 11.10.Ef
Nonseparability of continuously measured quantum systems in the classical limit
Authors: Ghose S , Sanders B C , Alsing P M , Deutsch I H 
Published: July 2007

We analyze the question of separability in a continuously measured quantum system as it approaches the classical limit. We show that the record of position measurements can approach the classical limit even when the system is described by highly nonseparable states. In particular, in systems with a chaotic classical limit, chaos can work to enhance the entanglement in the system in the classical regime. This coexistence of nonclassical states and classical dynamics can be understood by analyzing the conditioned evolution of the measured system and the conditions for the quantum-to-classical transition. PACS Nos.: 03.65.Ta, 03.65.Ud, 03.67.Mn, 05.45.Mt, 03.67.–a
Reflection and refraction of thermo-viscoelastic waves at the interface between two micropolar viscoelastic media without energy dissipation
Authors: Othman M I , Song Y Q 
Published: July 2007

Reflection and refraction of a plane harmonic wave at the interface between two viscoelastic media are studied under generalized thermo-viscoelastic theory. Using potential function, the governing equations reduce to two fourth-order ifferential equations. Coefficient ratios of reflection and refraction of different waves with the angle of incidence are obtained using continuous boundary conditions. By numerical calculations, the variation of coefficient ratios of reflection and refraction with the angle of incidence are illustrated graphically for aluminium–epoxy and magnesium crystal micropolar viscoelastic materials. Also, the effects of viscous and micropolar elastic are illustrated by numerical results in the theory of thermo-viscoelasticity without energy dissipation. PACS No.: 62.20.Dc
Experimental and theoretical basis of Lamb waves and their applications in material sciences
Authors: Sadler J , Maev R Gr 
Published: July 2007

The subject of Lamb waves contains a vast field of literature comprising many individual topics, with the current focus being the effective creation and use of Lamb waves in the fields of material characterization and nondestructive evaluation (NDE). This review chooses to focus on the more recent literature dealing with Lamb waves, giving introductions to a variety of topics. Because of the large amount of literature dealing with Lamb waves, many of the sections of this paper could themselves be expanded into their own literature review. This review begins with a brief introduction of Lamb waves comparing them to the acoustic bulk wave, and Rayleigh wave, and outlines the physics of a guided wave. It discusses the advantages of using guided waves, and theoretical techniques to model Lamb waves. In addition, the review discusses some of the various methods for the detection and creation of Lamb waves; techniques to detect, identify, and extract the mode from the acoustic signal; the use of Lamb waves in material characterization; flaw detection and flaw measurement; and finally examines the scattering of Lamb waves at plate ends and joints. While much of this work is experimentally based in nature, this review has attempted to also include theoretical work when possible. PACS Nos.: 43.90.+v, 81.70.Cv
Nematodes as a source of total coliforms in a distribution system
Authors: Locas Annie , Barbeau Benoit , Gauthier Vincent 
Published: July 2007

In a distribution system of a large North American city, recurring total coliforms and atypical coliforms were detected at the exit (distribution pumps) of a storage reservoir. The presence of total coliforms and atypical coliforms was noted when the pumps were in operation and the water temperature was higher than 18 °C. The total coliform and atypical coliform concentrations at the volute pump casings ranged from 0 to 93.5 colony forming units (cfu)/100 mL. Significant concentrations of nematodes were also detected at this sampling location, averaging 12.0 nematodes/L in 2001 and 17.4 nematodes/L in 2002. The hypothesis that coliforms were released from the nematodes during their transit through the high-pressure pump was tested by recovering nematodes by filtering large volumes of water and grinding the nematodes in the laboratory, using various techniques. Total coliform and heterotrophic bacteria concentrations ranged from 0 to 27 cfu/nematode and 0 to 643 cfu/nematode, respectively. The origin of the nematodes was traced back to the sand filters located at the two water treatment plants. The importance of invertebrates in the distribution system should not be dismissed and the associated health risks, if any, should be assessed.
Site-directed mutagenesis studies to probe the role of specific residues in the external loop (L3) of OmpF and OmpC porins in susceptibility ofSerratia marcescensto antibiotics
Authors: Begic Sanela , Worobec Elizabeth A. 
Published: July 2007

Serratia marcescens is a nosocomial bacterium with natural resistance to a broad spectrum of antibiotics, making treatment challenging. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, controlled in part by OmpF and OmpC porin proteins. To investigate the direct role of these porins in the diffusion of antibiotics across the outer membrane, we have created an ompF–ompC porin-deficient strain of S. marcescens. A considerable similarity between the S. marcescens porins and those from other members of Enterobacteriaceae was detected by sequence alignment, with the exception of a change in a conserved region of the third external loop (L3) of the S. marcescens OmpC protein. Serratia marcescens OmpC has aspartic acid instead of glycine in position 112, methionine instead of aspartic acid in position 114, and glutamine in position 124, while in S. marcescens OmpF this is a glycine at position 124. To investigate the role of amino acid positions 112, 114, and 124 and how the observed changes within OmpC porin may play a part in pore permeability, 2 OmpC sites were altered in the Enterobacteriaceae consensus (D112G and M114D) through site-directed mutagenesis. Also, Q124G in OmpC, G124Q in OmpF, and double mutants of these amino acid residues were constructed. Antibiotic accumulation assays and minimal inhibitory concentrations of the strains harboring the mutated porins were performed, while liposome swelling experiments were performed on purified porins. Our results demonstrate that the amino acid at position 114 is not responsible for either antibiotic size or ionic selection, the amino acid at position 112 is responsible for size selection only, and position 124 is involved in both size and ionic selection.
Replacing the general energy-coupling proteins of the phospho-enol-pyruvate:sugar phosphotransferase system ofSalmonella typhimuriumwith fructose-inducible counterparts results in the inability to utilize nonphosphotransferase system sugars
Authors: Sutrina Sarah L. , Inniss Patricia I. , Lazarus Leslie-Ann , Inglis Lizette , Maximilien Jacqueline 
Published: July 2007

A Salmonella typhimurium mutant lacking Enzyme I and HPr, general proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), but producing homologues EIFructoseand FPr constitutively, did not grow in minimal medium supplemented with non-PTS sugars (melibiose, glycerol, and maltose) in the absence of any trace of Luria–Bertani broth; adding cyclic AMP allowed growth. On melibiose, rapid growth began only when melibiose permease activity had reached a threshold level. Wild-type cultures reached this level within about 2 h, but the mutant only after a 12–14 h lag period, and then only when cyclic AMP had been added to the medium. On a mixture of melibiose and a PTS sugar, permease was undetectable in either the wild type or mutant until the PTS sugar had been exhausted. Permease then appeared, increasing with time, but in the mutant it never reached the threshold allowing rapid growth on melibiose unless cyclic AMP had been added. On rich medium supplemented with melibiose or glycerol, the mutant produced lower (30%) levels of melibiose permease or glycerol kinase compared with the wild type. We propose that poor phosphorylation of the regulatory protein Enzyme IIAGlucose, leading to constitutive inducer exclusion and catabolite repression in this strain, accounts for these results.
Occurrence of antibiotic-resistant bacteria and endotoxin associated with the land application of biosolids
Authors: Brooks J.P. , Maxwell S.L. , Rensing C. , Gerba C.P. , Pepper I.L. 
Published: July 2007

The purpose of this study was to determine the prevalence of antibiotic-resistant bacteria and endotoxin in soil after land application of biosolids. Soil was collected over a 15 month period following land application of biosolids, and antibiotic resistance was ascertained using clinically relevant antibiotic concentrations. Ampicillin, cephalothin, ciprofloxacin, and tetracycline resistance were all monitored separately for any changes throughout the 15 month period. Endotoxin soil concentrations were monitored using commercially available endotoxin analysis reagents. Overall, land application of biosolids did not increase the percentage of antibiotic-resistant culturable bacteria above background soil levels. Likewise, land application of biosolids did not significantly increase the concentration of endotoxin in soil. This study determined and established a baseline understanding of the overall effect that land application of biosolids had on the land-applied field with respect to antibiotic-resistant bacterial and endotoxin soil densities.
Biology and taxonomy ofBacillus cereus,Bacillus anthracis, andBacillus thuringiensis
Authors: Vilas-Bôas G.T. , Peruca A.P.S. , Arantes O.M.N. 
Published: July 2007

Three species of the Bacillus cereus group (Bacillus cereus, Bacillus anthracis , and Bacillus thuringiensis ) have a marked impact on human activity. Bacillus cereus and B. anthracis are important pathogens of mammals, including humans, and B. thuringiensis is extensively used in the biological control of insects. The microbiological, biochemical, and genetic characteristics of these three species are reviewed, together with a discussion of several genomic studies conducted on strains of B. cereus group. Using bacterial systematic concepts, we speculate that to understand the taxonomic relationship within this group of bacteria, special attention should be devoted also to the ecology and the population genetics of these species.
Cold-stress-altered phosphorylation of EF-Tu in the cyanobacterium Anabaena sp. strain PCC 7120
Authors: El-Fahmawi Bassam , Owttrim George W. 
Published: July 2007

Growth of prokaryotes at reduced temperature results in the formation of a cold-adapted ribosome through association with de novo synthesized polypeptides. In vitro and in vivo phosphorylation studies combined with affinity purification and mass spectrometry identified that the phosphorylation status of translation elongation factor EF-Tu was altered in response to cold stress in the photosynthetic, Gram-negative cyanobacterium Anabaena sp. strain PCC 7120. In response to a temperature downshift from 30 to 20 °C, EF-Tu was rapidly and transiently hyperphosphorylated during the acclimation phase followed by a reduction in phosphorylation below background levels in response to prolonged exposure. EF-Tu was identified as a phosphothreonine protein. Unexpectedly, ribosomal protein S2 was also observed to be a phosphoprotein continuously phosphorylated during cold stress. The phosphorylation status of EF-Tu has previously been associated with translational regulation in other systems, with a reduction in translation elongation occurring in response to phosphorylation. These results provide evidence for a novel mechanism by which translation is initially downregulated in response to cold stress in Anabaena.
Virus occurrence in municipal groundwater sources in Quebec, Canada
Authors: Locas Annie , Barthe Christine , Barbeau Benoit , Carrière Annie , Payment Pierre 
Published: July 2007

A 1 year study was undertaken on groundwater that was a source of drinking water in the province of Quebec, Canada. Twelve municipal wells (raw water) were sampled monthly during a 1 year period, for a total of 160 samples. Using historic data, the 12 sites were categorized into 3 groups: group A (no known contamination), group B (sporadically contaminated by total coliforms), and group C (historic and continuous contamination by total coliforms and (or) fecal coliforms). Bacterial indicators (total coliform, Escherichia coli , enteroccoci), viral indicators (somatic and male-specific coliphages), total culturable human enteric viruses, and noroviruses were analyzed at every sampling site. Total coliforms were the best indicator of microbial degradation, and coliform bacteria were always present at the same time as human enteric viruses. Two samples contained human enteric viruses but no fecal pollution indicators (E. coli, enterococci, or coliphages), suggesting the limited value of these microorganisms in predicting the presence of human enteric viruses in groundwater. Our results underline the value of historic data in assessing the vulnerability of a well on the basis of raw water quality and in detecting degradation of the source. This project allowed us to characterize the microbiologic and virologic quality of groundwater used as municipal drinking water sources in Quebec.
Development of 2 types of competitive enzyme-linked immunosorbent assay for detecting antibodies to the rinderpest virus using a monoclonal antibody for a specific region of the hemagglutinin protein
Authors: Khamehchian S. , Madani R. , Rasaee M.J. , Golchinfar F. , Kargar R. 
Published: July 2007

A competitive enzyme-linked immunosorbent assay (C-ELISA) has been developed and standardized for the detection of antibodies to the rinderpest virus (RPV) in sera from cattle, sheep, and goats. The test is specific for rinderpest because it does not detect antibodies to peste-des-petits-ruminants virus (PPRV). The test depends on the ability of the monoclonal antibody (MAb) directed against the hemagglutinin (H) protein of RPV to compete with the binding of RPV antibodies in the positive serum to the H protein of this virus. This MAb recognized a region from amino acids 575 to 583 on the H protein of RPV that is unique to the RPV H protein and is not present on the hemagglutinin-neuraminidase protein of PPRV. Another C-ELISA (peptide C-ELISA) was set up using this specific region as an antigen. A threshold value of 64.4% inhibition was established for the RPV C-ELISA, with 90 known RPV-negative and 30 RPV-positive serum samples. Using common serum samples, a cutoff value of 43.0% inhibition for the peptide C-ELISA was established. Based on statistical analysis, the overall sensitivity and specificity of the RPV C-ELISA, relative to those of a commercial kit, were found to be 90.00% and 103.33%, respectively. However, the sensitivity and specificity of the peptide C-ELISA were found to be 180.00% and 73.33%, respectively. Although a common MAb in 2 new C-ELISA systems was used, variation in their percent inhibition, due to the use of different antigens, was observed. Taking into consideration the difference in percent inhibition of the 2 described assays and the commercial kit (50%), it was found that the RPV C-ELISA and the peptide C-ELISA are more specific and sensitive tools than the commercial kit for assessing herd immune status and for epidemiologic surveillance.
Cellular functions and transcriptional regulation of a third thioredoxin from Schizosaccharomyces pombe
Authors: Kim Su-Jung , Jung Eui-Man , Jung Hyun-Joo , Song Yun Seon , Park Eun-Hee , Lim Chang-Jin 
Published: July 2007

The structural gene encoding a third thioredoxin (Trx) homologue, TRX3, of the fission yeast Schizosaccharomyces pombe was characterized and its regulation was studied. The determined DNA sequence encoded a putative 290 amino acid sequence of Trx with a molecular mass of 31 889 Da. The TRX3 mRNA level was increased in S. pombe cells harboring plasmid pTRX3, suggesting that the cloned TRX3 gene was functional. Yeast cultures harbouring plasmid pTRX3 exhibited shorter generation times and higher survival on solid minimal media plates incorporating mercury chloride (0.01 mmol/L) or hydrogen peroxide (1 mmol/L) compared with control cultures. Yeast cells containing extra copies of TRX3, but not TRX1 and TRX2, gave rise to lower reactive oxygen species levels than control cells. Oxidative stress owing to hydrogen peroxide and menadione enhanced the synthesis of β-galactosidase from the TRX3–lacZ fusion gene in Pap1-positive cells but not in Pap1-negative cells. The TRX3 mRNA level was increased by oxidative stress only in Pap1-positive cells. Basal expression of the TRX3 gene also depended on Pap1. We concluded that S. pombe TRX3 is linked with yeast growth and oxidative stress response, with its expression being regulated by oxidative stress in a Pap1-dependent manner.
Genetic variation of growth rhythm traits in the limits of a latitudinal cline in Scots pine
Authors: Notivol E. , García-Gil M. R. , Alía R. , Savolainen O. 
Published: July 2007

Scots pine ( Pinus sylvestris L.) has the widest distribution of pine species and the populations are locally adapted to very different environmental conditions. Adaptive traits such as those related to growth are optimal for understanding adaptation of populations to local conditions in widely distributed forest species. A study of the timing of growth during the first growing period of families in four populations from the latitudinal limits of the distribution range was conducted. Individual growth curves were fitted, and a set of variables related to growth rhythm and timing of budset was obtained for genetic analyses. Pooled heritabilities across populations were very high for most of the traits (0.43–1.09), and population differentiation for growth variables showed high values as well (QST= 0.19–0.71). Phenotypic correlations were higher than genetic ones, and most of them were positives. Even no general patterns of additive variances were found, the high additive genetic variance obtained (14% ± 8%, mean ± SE) suggests that additive genetic variance is not the limiting factor for adaptation to a new optimum within much of the range for these traits. Changes in means, additive genetic variances, and additive genetic coefficient of variation by population are also discussed.
The reduction of organic-layer depth by wildfire in the North American boreal forest and its effect on tree recruitment by seed
Authors: Greene David F. , Macdonald S. Ellen , Haeussler Sybille , Domenicano Susy , Noël Josée , Jayen Karelle , Charron Isabelle , Gauthier Sylvie , Hunt Simon , Gielau E. Trent , Bergeron Yves , Swift Lynn 
Published: July 2007

We compared prefire and postfire organic-layer depths in boreal forest types (14 fires) across Canada, and examined tree recruitment as a function of depth. There was extensive within-stand variation in depth, much of it due to clustering of thinner organic layers around boles. There were no significant differences in postfire organic-layer depth among sites with different prefire forest species composition, but sites in the eastern boreal region had thicker postfire organic layers than those in the western boreal region. Mean organic-layer depth was much greater in intact stands than after fires; overall, fire reduced organic-layer depth by 60%, largely because of increases in the area of thin (<3 cm) organic layers (1% in intact stands vs. 40% in postfire stands). There was more variation in organic-layer depth within postfire than within prefire stands; notably, some areas in postfire stands were deeply combusted, while adjacent parts were only lightly combusted. We speculate that the diminished role of energy loss to latent heat around tree boles increased organic-layer consumption around tree boles. Seedlings were clustered around burned tree bases, where organic layers were thinner, and the dependence of a species on thin organic layers was an inverse function of seed size.
Effects of logging in the southern boreal peatlands of Manitoba, Canada
Authors: Locky David A. , Bayley Suzanne E. 
Published: July 2007

To evaluate changes in surface water chemistry, peat, and the plant community in logged peatlands, we compared plots in 1–4 year old (class I) and 9–12 year old (class II) clearcuts with plots in wooded controls. Indicator species were significantly different between wooded and clear-cut plots but not between clear-cut plot age classes. Surface waters in class I clearcuts had significantly higher temperature and nutrients compared with controls, and this was attributed to warming of the soil, which resulted in faster decomposition and greater nutrient availability. Hummocks, important peatland plant microhabitats, were reduced in height in all clearcuts because of compaction and abrasion. These abiotic changes caused a shift in the plant community. Total plant diversity was approximately 30% higher on clearcuts and consisted primarily of herbs, particularly grasses. However, bryophyte and lichen diversity and cover was greatest in wooded controls. Picea mariana (Mill.) BSP regeneration was not compromised by clear-cutting and was greater in class II clearcuts. Greater diversity and cover of Salix species in class II clearcuts suggests stable shrub community formation, which may be persistent and may slow succession. The use of appropriate equipment to minimize site disturbances while the ground is frozen may reduce long-term shifts in the plant community.