bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary Genetic Analysis of the Emergence of Epidemic
Vibrio cholerae
Isolates on the Basis of Comparative Nucleotide Sequence Analysis and Multilocus Virulence Gene Profiles
Authors: O'Shea Yvonne A. , Reen F. Jerry , Quirke Anne Marie , Boyd E. Fidelma
Published: October 2004

Vibrio cholerae
, the causative agent of cholera, is a natural inhabitant of the aquatic ecosystem. We examined a unique collection of
V. cholerae
clinical and environmental isolates of widespread geographic distribution recovered over a 60-year period to determine their evolutionary genetic relationships based on analysis of two housekeeping genes, malate dehydrogenase (
mdh
) and a chaperonin (
groEL
). In addition, the phylogenetic distribution of 12 regions associated with virulence was determined. Comparative sequence analysis of
mdh
revealed that all
V. cholerae
O1 and O139 serogroup isolates belonged to the same clonal lineage. Single-strand conformational polymorphism (SSCP) analysis of these O1 and O139 strains at
groEL
confirmed the presence of an epidemic clonal complex. Of the 12 virulence regions examined, only three regions,
Vibrio
seventh pandemic island 1 (VSP-I), VSP-II, and RS1, were absent from all classical
V. cholerae
isolates. Most
V. cholerae
El Tor biotype and O139 serogroup isolates examined encoded all 12 virulence regions assayed. Outside of
V. cholerae
O1/O139 serogroup isolates, only one strain, VO7, contained VSP-I. Two
V. cholerae
El Tor isolates, GP155 and 2164-78, lacked both VSP-I and VSP-II, and one El Tor isolate, GP43, lacked VSP-II. Five non-O1/non-O139 serogroup isolates had an
mdh
sequence identical to that of the epidemic O1 and O139 strains. These isolates, similar to classical strains, lack both VSP-I and VSP-II. Four of the 12 virulence regions examined were found to be present in all isolates:
hlyA
,
pilE
, MSHA and RTX. Among non-O1/non-O139 isolates, however, the occurrence of the additional eight regions was considerably lower. The evolutionary relationships and multilocus virulence gene profiles of
V. cholerae
natural isolates indicate that consecutive pandemic strains arose from a common O1 serogroup progenitor through the successive acquisition of new virulence regions.
Phylogeny, Clinical Associations, and Diagnostic Utility of the Pilin Subunit Gene (
sfpA
) of Sorbitol-Fermenting, Enterohemorrhagic
Escherichia coli
O157:H
−
Authors: Friedrich Alexander W. , Nierhoff Katja V. , Bielaszewska Martina , Mellmann Alexander , Karch Helge
Published: October 2004

The plasmid-borne
sfpA
gene encodes the pilin subunit in sorbitol-fermenting (SF) enterohemorrhagic
Escherichia coli
(EHEC) O157:H
−
. We investigated the distribution of
sfpA
among 600
E. coli
isolates comprising the complete
E. coli
standard reference (ECOR) and diarrheagenic
E. coli
(DEC) strain collections and clinical isolates associated with enteric disease.
sfpA
was detected in DEC3F SF EHEC O157:H
−
strain 493/89, each of 107 SF EHEC O157:H
−
clinical isolates, and 14 Shiga toxin-negative SF
E. coli
O157:H
−
strains which contained
eae
, which encodes γ-intimin, and
fliC
, which encodes the H7 antigen.
sfpA
was absent from all other strains, including the ECOR strain collection, all non-SF EHEC O157:H7 strains, and all
E. coli
O55:H7 strains (
E. coli
O55:H7 is the postulated ancestor of Shiga toxin-producing
E. coli
[STEC] O157). These results suggest that there was a single acquisition of the
sfpA
gene in the nonmotile SF
E. coli
O157 branch, presumably after the
eae
-encoding pathogenicity island (the locus of enterocyte effacement) was acquired and motility was lost. We then applied the
sfpA
PCR in combination with
rfb
O157
,
stx
, and
eae
PCRs to screen 636 stool samples from patients with diarrhea or hemolytic-uremic syndrome for SF STEC O157:H
−
. In 27 cases, the simultaneous presence of the
sfpA
,
eae
, and
rfb
O157
amplicons indicated the presence of SF
E. coli
O157:H
−
strains, and the result was subsequently confirmed by isolation. All but two of these strains possessed
stx
2
. None of the other stool samples was positive by the
sfpA
PCR; 59 of these stool samples contained EHEC O157:H7. The
sfpA
gene can be recommended as a target for screening for SF
E. coli
O157:H
−
.
Differential Expression of Secretory Aspartyl Proteinase Genes (
SAP1
-
10
) in Oral
Candida albicans
Isolates with Distinct Karyotypes
Authors: Tavanti Arianna , Pardini Giacomo , Campa Daniele , Davini Paola , Lupetti Antonella , Senesi Sonia
Published: October 2004

Two karyotypes of oral
Candida albicans
isolates, named b and c, constituted >80% of a collection from healthy carriers (22 b and 16 c isolates) and oral candidiasis patients who were either infected (31 b and 16 c isolates) or uninfected (13 b and 38 c isolates) with human immunodeficiency virus (HIV). The prevalence of the b and c karyotypes within HIV-positive and HIV-negative patients, respectively, who were suffering from oral candidiasis (
P
≤ 0.0001) suggested that these two types possessed different virulence potentials. Since
C. albicans
proteinases (Saps) are virulence factors in oral candidiasis, we evaluated whether the b and c karyotypes secreted different levels of Saps and expressed different patterns of Sap-encoding genes (
SAP1
-
10
). We found that the mean value of Sap activity was significantly lower (
P
= 0.003) in the commensal type than in the infectious b karyotype, whereas Sap activity in the commensal c type was as high as that registered for the infectious c strains. Marked differences in
SAP
mRNA expression were observed in commensal strains under non-Sap-inducing conditions, with all
SAP
genes being expressed only by strains with the c karyotype; interestingly, none of the commensal b strains expressed
SAP2
. In addition, while all of the
SAP1
-
10
genes were detectable under Sap-inducing conditions, the timing of their expression during growth differed significantly, with mRNAs of
SAP1
-
10
genes detected at 8 and 24 h postinoculation in c and b commensal strains, respectively. This provides the first evidence that commensal oral
C. albicans
isolates with distinct karyotypes are characterized by different patterns of
SAP1
-
10
gene expression and different levels of Sap secretion.
Genetic Diversity among Community Methicillin-Resistant
Staphylococcus aureus
Strains Causing Outpatient Infections in Australia
Authors: Coombs Geoffrey W. , Nimmo Graeme R. , Bell Jan M. , Huygens Flavia , O'Brien Frances G. , Malkowski Mary J. , Pearson Julie C. , Stephens Alex J. , Giffard Philip M.
Published: October 2004

Increasing reports of the appearance of novel nonmultiresistant methicillin-resistant
Staphylococcus aureus
MRSA (MRSA) strains in the community and of the spread of hospital MRSA strains into the community are cause for public health concern. We conducted two national surveys of unique isolates of
S. aureus
from clinical specimens collected from nonhospitalized patients commencing in 2000 and 2002, respectively. A total of 11.7% of 2,498 isolates from 2000 and 15.4% of 2,486 isolates from 2002 were MRSA. Approximately 54% of the MRSA isolates were nonmultiresistant (resistant to less than three of nine antibiotics) in both surveys. The majority of multiresistant MRSA isolates in both surveys belonged to two strains (strains AUS-2 and AUS-3), as determined by pulsed-field gel electrophoresis (PFGE) and resistogram typing. The 3 AUS-2 isolates and 10 of the 11 AUS-3 isolates selected for multilocus sequence typing (MLST) and staphylococcal chromosomal cassette
mec
(SCC
mec
) analysis were ST239-MRSA-III (where ST is the sequence type) and thus belonged to the same clone as the eastern Australian MRSA strain of the 1980s, which spread internationally. Four predominant clones of novel nonmultiresistant MRSA were identified by PFGE, MLST, and SCC
mec
analysis: ST22-MRSA-IV (strain EMRSA-15), ST1-MRSA-IV (strain WA-1), ST30-MRSA-IV (strain SWP), and ST93-MRSA-IV (strain Queensland). The last three clones are associated with community acquisition. A total of 14 STs were identified in the surveys, including six unique clones of novel nonmultiresistant MRSA, namely, STs 73, 93, 129, 75, and 80slv and a new ST. SCC
mec
types IV and V were present in diverse genetic backgrounds. These findings provide support for the acquisition of SCC
mec
by multiple lineages of
S. aureus
. They also confirm that both hospital and community strains of MRSA are now common in nonhospitalized patients throughout Australia.
Two Novel Real-Time Reverse Transcriptase PCR Assays for Rapid Detection of Bacterial Contamination in Platelet Concentrates
Authors: Dreier Jens , Störmer Melanie , Kleesiek Knut
Published: October 2004

The incidence of platelet bacterial contamination is approximately 1 per 2,000 units and has been acknowledged as the most frequent infectious risk from transfusion. In preliminary studies, the sterility of platelet concentrates (PCs) was tested with an automated bacterial blood culturing system and molecular genetic assays. Two real-time reverse transcriptase PCR (RT-PCR) assays performed in a LightCycler instrument were developed and compared regarding specificity and sensitivity by the use of different templates to detect the majority of the clinically important bacterial species in platelets. Primers and probes specific for the conserved regions of the eubacterial 23S rRNA gene or the
groEL
gene (encoding the 60-kDa heat shock protein Hsp60) were designed. During the development of the 23S rRNA RT-PCR, problems caused by the contamination of reagents with bacterial DNA were noted. Treatment with 8-methoxypsoralen and UV irradiation reduced the level of contaminating DNA. The sensitivity of the assays was greatly influenced by the enzyme system which was used. With r
Tth
DNA polymerase in a one-enzyme system, we detected 500 CFU of
Escherichia coli
or
Staphylococcus epidermidis
/ml. With a two-enzyme system consisting of Moloney murine leukemia virus RT and
Taq
DNA polymerase, we detected 16 CFU/ml. With
groEL
mRNA as the target of RT-PCR under optimized conditions, we detected 125 CFU of
E. coli
/ml, and no problems with false-positive results caused by reagent contamination or a cross-reaction with human nucleic acids were found. Furthermore, the use of mRNA as an indicator of viability was demonstrated. Here we report the application of novel real-time RT-PCR assays for the detection of bacterial contamination of PCs that are appropriate for transfusion services.
Comparison of Trends of Resistance Rates over 3 Years Calculated from Results for All Isolates and for the First Isolate of a Given Species from a Patient
Authors: Lee Sang-Oh , Cho Yong Kyun , Kim Sue-Yun , Lee Eun Sun , Park Shin Young , Seo Yiel-Hae
Published: October 2004

We compared trends of annual resistance rates calculated from results for all isolates and for the first isolate of
Staphylococcus aureus
,
Klebsiella pneumoniae
, and
Acinetobacter baumannii
per patient over a 3-year period from 2001 through 2003. Antimicrobial susceptibility results of inpatients were extracted from a computerized database. Annual resistance rates of a species were calculated by two methods: (i) from results for all isolates, even those from patients with multiple isolates in a given year and (ii) from results for the first isolate from a patient in a given year, regardless of susceptibility profile or specimen type. Rates of methicillin-resistant
S. aureus
(MRSA) did not differ among all isolates (79.9, 78.8 and 79.6%;
P
= 0.86), but decreased for the first isolate per patient (70.2, 65.7, and 64.1%;
P
= 0.006) over time. Annual duplication rates of methicillin-susceptible
S. aureus
(MSSA) decreased (39.6, 37.6, and 31.7%;
P
= 0.01), but those of MRSA increased significantly (64.3, 67.8, and 68.9%;
P
= 0.004). Rates of cefotaxime-resistant
K. pneumoniae
did not differ over time by either method, and rates of imipenem-resistant
A. baumannii
decreased over time by both methods. Duplication rates did not differ for either susceptible or resistant isolates of
K. pneumoniae
and
A. baumannii
. The trends in MRSA rate differed by the two methods because of the different proportion of duplicate isolates per year. MRSA rates might be increasingly overestimated for all isolates. These results suggest that the method of calculating results for the first isolate per patient may remove the effect of duplication, allowing the simple and unambiguous analysis of cumulative susceptibility rates.
Tobacco Agar, a New Medium for Differentiating
Candida dubliniensis
from
Candida albicans
Authors: Khan Zia U. , Ahmad Suhail , Mokaddas Eiman , Chandy Rachel
Published: October 2004

Isolates of
Candida dubliniensis
may be misidentified as
Candida albicans
in microbiological laboratories if only the germ tube and/or the chlamydospore test is used for identification to the species level. In this study, we have evaluated the efficacy of tobacco agar for the differentiation of
C. dubliniensis
from
C. albicans
. On this medium at 28°C, all 30
C. dubliniensis
isolates produced yellowish-brown colonies with hyphal fringes and abundant chlamydospores, whereas 54
C. albicans
isolates formed smooth, white-to-cream-colored colonies with no chlamydospore production. This medium provides a simple tool for presumptive differentiation of
C. dubliniensis
from
C. albicans
.
New Method for Laboratory Detection of AmpC β-Lactamases in
Escherichia coli
and
Klebsiella pneumoniae
Authors: Nasim K. , Elsayed S. , Pitout J. D. D. , Conly J. , Church D. L. , Gregson D. B.
Published: October 2004

A new cefoxitin-agar medium (CAM)-based assay was compared to the previously published modified three-dimensional (M3D) assay for the detection of AmpC production in
Escherichia coli
and
Klebsiella pneumoniae
. Clinical isolates of cefoxitin-resistant
E. coli
(
n
= 5) and
K. pneumoniae
(
n
= 7) and multiple control strains with and without AmpC enzymes were tested by both methods. The CAM method with 4 μg of cefoxitin/ml was equivalent to the M3D method for detecting AmpC production in
E. coli
and
K. pneumoniae
. This new method is easier to perform and interpret and allows for testing of multiple isolates on a single plate.
In Vitro Antifungal Susceptibility of
Cryptococcus gattii
Authors: Trilles Luciana , Fernández-Torres Belkys , dos Santos Lazéra Márcia , Wanke Bodo , Guarro Josep
Published: October 2004

We have determined the in vitro susceptibilities of 57 strains of
Cryptococcus gattii
to nine antifungal agents and have compared the MICs for these strains with those for
C. neoformans
. MICs were determined by a microdilution reference method. Albaconazole and ravuconazole (MICs of 0.04 and 0.05 μg/ml, respectively) showed the best activities. Micafungin showed no activity (MIC of >128 μg/ml). In general,
C. gattii
was less susceptible than
C. neoformans
to all drugs tested, with the exception of amphotericin B and flucytosine.
Species Distribution and Ribotype Diversity of
Burkholderia cepacia
Complex Isolates from French Patients with Cystic Fibrosis
Authors: Brisse Sylvain , Cordevant Christophe , Vandamme Peter , Bidet Philippe , Loukil Chawki , Chabanon Gérard , Lange Marc , Bingen Edouard
Published: October 2004

A total of 153
Burkholderia cepacia
strains obtained from 153 French patients with cystic fibrosis were identified as
Burkholderia multivorans
(51.6%) or
Burkholderia cenocepacia
(45.1%). Eighty-two genotypes were identified using PvuII and EcoRI ribotyping.
B. multivorans
genotype A (found in 32 French patients) and two other genotypes were also identified among isolates from Austrian, German, Italian, and Canadian patients.
Detection of Catheter-Related Bloodstream Infections by the Differential-Time-to-Positivity Method and Gram Stain-Acridine Orange Leukocyte Cytospin Test in Neutropenic Patients after Hematopoietic Stem Cell Transplantation
Authors: Krause R. , Auner H. W. , Gorkiewicz G. , Wölfler A. , Daxboeck F. , Linkesch W. , Krejs G. J. , Wenisch C. , Reisinger E. C.
Published: October 2004

For febrile neutropenic patients who received hematopoietic stem cell transplantation, the Gram stain-acridine orange leukocyte cytospin (AOLC) test and the differential-time-to-positivity method (DTP) were performed. As a diagnostic tool for catheter-related bloodstream infections in these patients, the Gram stain-AOLC test has a lower sensitivity than does the DTP method but acceptable positive and negative predictive values.
Multiplex Detection of Mutations in Clinical Isolates of Rifampin-Resistant
Mycobacterium tuberculosis
by Short Oligonucleotide Ligation Assay on DNA Chips
Authors: Deng Jiao-Yu , Zhang Xian-En , Lu Hong-Bing , Liu Qiang , Zhang Zhi-Ping , Zhou Ya-Feng , Xie Wei-Hong , Fu Zhi-Jun
Published: October 2004

A new approach, short-oligonucleotide-ligation assay on DNA chip (SOLAC), is developed to detect mutations in rifampin-resistant
Mycobacterium tuberculosis
. The method needs only four common probes to detect 15 mutational variants of the
rpoB
gene within 12 h. Fifty-five rifampin-resistant
M. tuberculosis
isolates were analyzed, resulting in 87.3% accuracy and 83.6% concordance relative to DNA sequencing.
Performance of the Binax NOW
Streptococcus pneumoniae
Urinary Antigen Assay for Diagnosis of Pneumonia in Children with Underlying Pulmonary Diseases in the Absence of Acute Pneumococcal Infection
Authors: Navarro David , García-Maset Leonor , Gimeno Concepción , Escribano Amparo , García-de-Lomas Juan
Published: October 2004

The performance of the Binax NOW immunochromatographic test for detecting
Streptococcus pneumoniae
antigen in urine specimens from 103 children presenting underlying pulmonary diseases with no recent pneumococcal infection was assessed. Our data indicate that this assay is unlikely to be useful for discriminating between children with and without pneumococcal pneumonia.
Routine Use of a Commercial Test, GLABRATA RTT, for Rapid Identification of
Candida glabrata
in Six Laboratories
Authors: Freydiere A. M. , Perry J. D. , Faure O. , Willinger B. , Tortorano A. M. , Nicholson A. , Peman J. , Verweij P. E.
Published: October 2004

When evaluated in six clinical laboratories from six countries with 1,174 fresh isolates, including 715
Candida glabrata
and 459 non-
C. glabrata
strains, GLABRATA RTT (Fumouze Diagnostics, Levallois Perret, France) yielded an overall sensitivity and an overall specificity of 95.8 and 98.9%, respectively. The results were consistent from one laboratory to another. The five false-positive results corresponded to
C. parapsilosis
(
n
= 2),
C. tropicalis
,
C. guilliermondii
, and
C. lusitaniae.
GLABRATA RTT allows a rapid, cost-effective, and reliable presumptive identification of
C. glabrata
.
HBsAg Seroclearance in Chinese Patients Receiving Lamivudine Therapy for Chronic Hepatitis B Virus Infection
Authors: Yuen Man-Fung , Wong Danny Ka-Ho , Yuan He-Jun , Sum Siu-Man , Lai Ching-Lung
Published: October 2004

We report two Chinese patients in whom lamivudine treatment resulted in HBsAg seroclearance. One patient received lamivudine, and another patient received 12-week famciclovir treatment followed by lamivudine. Lamivudine was maintained after HBeAg seroconversion. These two patients lost HBsAg at 24 and 27 months (ages, 23 and 19.3 years, respectively) and developed measurable titer of anti-HBs after 65 and 71 months of therapy, respectively. The liver biochemistry was normal after HBeAg seroconversion. The serum hepatitis B virus (HBV) DNA levels were undetectable (<200 copies/ml) both at the time of HBeAg seroconversion and at the last follow-up. Liver biopsy of one patient showed nearly normal histology, with undetectable intrahepatic total HBV DNA and covalently closed circular DNA. In conclusion, lamivudine therapy can result in HBsAg seroclearance at an early age even though the phenomenon is rare.
Detection of
Bartonella quintana
by Direct Immunofluorescence Examination of Blood Smears of a Patient with Acute Trench Fever
Authors: Foucault C. , Rolain J. M. , Raoult D. , Brouqui P.
Published: October 2004

We report a case of
Bartonella quintana
acute symptomatic infection in a homeless man, presenting as a typical trench fever.
B. quintana
has been retrieved in erythrocytes in large clusters and in erythroblasts. Direct immunofluorescence of blood smears allows a rapid diagnosis.
Issues in the reporting of epidemiological studies: a survey of recent practice
Authors: Pocock Stuart J , Collier Timothy J , Dandreo Kimberley J , de Stavola Bianca L , Goldman Marlene B , Kalish Leslie A , Kasten Linda E , McCormack Valerie A
Published: October 2004

Objectives
To review current practice in the analysis and reporting of epidemiological research and to identify limitations.

Design
Examination of articles published in January 2001 that investigated associations between risk factors/exposure variables and disease events/measures in individuals.

Setting
Eligible English language journals including all major epidemiological journals, all major general medical journals, and the two leading journals in cardiovascular disease and cancer.

Main outcome measure
Each article was evaluated with a standard proforma.

Results
We found 73 articles in observational epidemiology; most were either cohort or case-control studies. Most studies looked at cancer and cardiovascular disease, even after we excluded specialty journals. Quantitative exposure variables predominated, which were mostly analysed as ordered categories but with little consistency or explanation regarding choice of categories. Sample selection, participant refusal, and data quality received insufficient attention in many articles. Statistical analyses commonly used odds ratios (38 articles) and hazard/rate ratios (23), with some inconsistent use of terminology. Confidence intervals were reported in most studies (68), though use of P values was less common (38). Few articles explained their choice of confounding variables; many performed subgroup analyses claiming an effect modifier, though interaction tests were rare. Several investigated multiple associations between exposure and outcome, increasing the likelihood of false positive claims. There was evidence of publication bias.

Conclusions
This survey raises concerns regarding inadequacies in the analysis and reporting of epidemiological publications in mainstream journals.
CONSERVATION LAWS FOR THE CLASSICAL TODA FIELD THEORIES
Authors: HOHLER ERLING G. B. , OLAUSSEN KÅRE
Published: October 2004

Some explicit calculations of the conservation laws for classical (affine) Toda field theories, and some generlizations of these models are performed. We show that there is a huge class of generalized models which have an infinite set of conservation laws, with their integrated charges being in involution. Amongst these models we find that only the Am, and [Formula: see text] Toda field theories admit such conservation laws for spin-3. The explicit calculations of spin-4 and spin-5 conservation laws in the (affine) Toda models we presented. Our perhaps most interesting finding is that there exist conservation laws in the Am, models (m≥4) which have a different origin than the exponents of the corresponding affine theory or the energy-momentum tensor of a conformal theory.
COMMENTS ON THE STANDARD MODEL OF ELECTROWEAK INTERACTIONS
Authors: MACHET B.
Published: October 2004

The Standard Model of electroweak interactions is shown to include a gauge theory for the observed scalar and pseudoscalar mesons. This is done by exploiting the consequences of embedding the SU(2)L×U(1) group into the chiral group of strong interactions and by explicitly considering as composite the Higgs boson and its three companions inside the standard scalar four-plet. No extra scale of interaction is needed. Quantizing by the Feynman path integral reveals how, in the “Nambu-Jona-Lasinio approximation,” the quarks and the Higgs boson become unobservable, and the theory anomaly-free. Nevertheless, the “anomalous” couplings of the pseudoscalar mesons to gauge fields spring again from the constraints associated with their compositeness itself. This work is the complement of Ref. 1, where the leptonic sector was shown to be compatible with a purely vectorial theory and, consequently, to be also anomaly-free. The bond between quarks and leptons loosens.
STRUCTURE CONSTANTS OF THE D5, CHIRAL, MINIMAL MODEL
Authors: MCCABE J. , SAMI T. , WYDRO T.
Published: October 2004

The operator product algebra of the simplest chiral, minimal model, D5, in the ADE classification, is determined. The construction uses the Coulomb gas technique that was already employed in the nonchiral A series. This technique is supplemented by conformal blocks special to the D series. Explicit results for the structure constants of three-point correlations are given. They demonstrate that the ground state has a discrete symmetry, Z2.
OSCILLATIONS OF A NEUTRINO BACKGROUND: A FIELD-THEORETIC TREATMENT
Authors: D’OLIVO J.C. , NIEVES JOSÉ F.
Published: October 2004

We give a field-theoretic treatment of the behavior of mixed neutrinos in media such as the early universe or the core of a supernova, where the neutrinos themselves are part of the background. The contributions to the self-energy coming from the neutrino internal lines must be calculated in terms of the propagator corresponding to the neutrino modes in the medium, instead of the thermal free propagator. The use of the effective field associated with these modes allows us to express the neutrino densities in terms of the dynamical flavor amplitudes in precise form. We show how the damping terms in the Hamiltonian matrix that governs the flavor evolution are determined from the absorptive part of the self-energy. Our work extends the thermal-field-theory method to a nonlinear problem where it was thought not to be applicable, and provides a simpler alternative to the Boltzmann-type kinetic approach.
CALCULATION OF GROMOV-WITTEN INVARIANTS FOR CP3, CP4AND Gr(2, 4)
Authors: JINZENJI MASAO , SUN YI
Published: October 2004

Using the associativity relations of the topological sigma models with target spaces, CP3, CP4 and Gr (2, 4), we derive recursion relations of their correlation and evaluate them up to a certain order in the expansion over the instantons. The expansion coefficients are regarded as the number of rational curves in CP3, CP4 and Gr (2, 4) which intersect various types of submanifolds corresponding to the choice of BRST-invariant operators in the correlation functions.
THE LOW ENERGY EFFECTIVE LAGRANGIAN FOR PHOTON INTERACTIONS IN ANY DIMENSION
Authors: RITZ A. , DELBOURGO R.
Published: October 2004

The subject of low energy photon-photon scattering is considered in arbitrary-dimensional space-time and the interaction is widened to include scattering events involving an arbitrary number of photons. The effective interaction Lagrangian for these processes in QED has been determined in a manifestly invariant form. This generalization resolves the structure of the weak field Euler-Heisenberg Lagrangian and indicates that the component invariant functions have coefficients related not only to the space-time dimension but also to the coefficients of the Bernoulli polynomial.
PCAC CONSISTENCY: PION DECAYS OF KAON AND ETA MESONS
Authors: KARLSEN R.E. , SCADRON M.D. , CHOUDHURY S.R.
Published: October 2004

PCAC consistency is reviewed for K0→ππ and K→3π decays. It is then extended to η→3π decays. In all eight decays the PCAC-consistency amplitudes uniformly map out the observed amplitudes to within 5%.
MEAN FIELD DESCRIPTION OF THE FRACTIONAL QUANTUM HALL EFFECT NEAR ν=1/(2k+1)
Authors: CURNOE STEPHANIE , WEISS NATHAN
Published: October 2004

We study the nature of mean field solutions to the equations of motion of the Chern-Simons Landau-Ginzburg (CSLG) description of the fractional quantum Hall effect (FQHE). Beginning with the conventional description of this model at some chemical potential μ0 and magnetic field B corresponding to a “special” filling fraction ν=2πρ/ eB=1/n (n=1, 3, 5,…), we show that a deviation of µ in a finite range around μ0 does not change the mean field solution and thus the mean density of particles in the model. This result holds not only for the lowest energy mean field solution but also for the vortex excitations. The vortex configurations do not depend on µ in a finite range about μ0 in this model. However, when [Formula: see text] the lowest energy mean field solution describes a condensate of vortices (or antivortices). We give numerical examples of vortex and antivortex configurations and discuss the range of µ and ν over which the system of vortices is dilute.
BIG BANG NUCLEOSYNTHESIS: AN UPDATE
Authors: OLIVE KEITH A. , SCULLY SEAN T.
Published: October 2004

The current status of big bang nucleosynthesis is reviewed with an emphasis on the comparison between the observational determination of the light element abundances of D , 3 He , 4 He and 7 Li and the predictions from theory. In particular, we present new analyses for 4 He and 7 Li . Implications for physics beyond the standard model are also discussed. In addition, limits on the effective number of neutrino flavors are updated.
MULTISTRING VERTICES AND HYPERBOLIC KAC-MOODY ALGEBRAS
Authors: GEBERT R.W. , NICOLAI H. , WEST P.C.
Published: October 2004

Multistring vertices and the overlap identities which they satisfy are exploited to understand properties of hyperbolic Kac-Moody algebras, in particular E10. Since any such algebra can be embedded in the larger Lie algebra of physical states of an associated completely compactified subcritical bosonic string, one can in principle determine the root spaces by analyzing which (positive norm) physical states decouple from the N-string vertex. Consequently, the Lie algebra of physical states decomposes into a direct sum of the hyperbolic algebra and the space of decoupled states. Both these spaces contain transversal and longitudinal states. Longitudinal decoupling holds more generally, and may also be valid for uncompactified strings, with possible consequences for Liouville theory; the identification of the decoupled states simply amounts to finding the zeroes of certain “decoupling polynomials.” This is not the case for transversal decoupling, which crucially depends on special properties of the root lattice, as we explicitly demonstrate for a nontrivial root space of E10· Because the N-vertices of the compactified string contain the complete information about decoupling, all the properties of the hyperbolic algebra are encoded into them. In view of the integer grading of hyperbolic algebras such as E10 by the level, these algebras can be interpreted as interacting strings moving on the respective group manifolds associated with the underlying finite-dimensional Lie algebras.
NONCOMMUTATIVE GEOMETRY AND A DISCRETIZED VERSION OF KALUZA-KLEIN THEORY WITH A FINITE FIELD CONTENT
Authors: VIET NGUYEN AI , WALI KAMESHWAR C.
Published: October 2004

We consider a four-dimensional space-time supplemented by two discrete points assigned to a Z2-algebraic structure and develop the formalism of noncommutative geometry. By setting up a generalized vielbein, we study the metric structure. Metric-compatible torsion-free connection defines a unique finite field content in the model and leads to a discretized version of Kaluza-Klein theory. We study some special cases of this model that illustrate the rich and complex structure with massive modes and the possible presence of a cosmological constant.
REMARKS ON THE W PROPAGATOR AT THE RESONANCE
Authors: CASTRO G. LÓPEZ , LUCIO M. J.L. , PESTIEAU J.
Published: October 2004

We address the problem of properly defining the W± propagator in the resonance region. Particular attention is paid to the longitudinal piece of this propagator. We also discuss the related renormalization procedures and the unitarity property.
PION FORM FACTORS AT INTERMEDIATE MOMENTUM TRANSFER IN A COVARIANT APPROACH
Authors: SZCZEPANIAK ADAM , WILLIAMS ANTHONY G.
Published: October 2004

We study the pion electromagnetic and γ*+π0→γ transition form factors at intermediate momentum transfer. We calculate soft, nonperturbative corrections to the leading perturbative amplitudes which arise from the [Formula: see text] component of the pion wave function. We work in Minkowski space and use a Lorentz-covariant, gauge-invariant generalized perturbative integral representation for the [Formula: see text] amplitudes. For the transition form factor we find relative insensitivity to the detailed nonperturbative structure of the wave function for |q2|≳10 GeV 2, whereas considerable sensitivity is found for the electromagnetic form factor.
INTEGRABLE PERTURBATIONS OF CFT WITH COMPLEX PARAMETER: THE M3/5 MODEL AND ITS GENERALIZATIONS
Authors: RAVANINI F. , STANISHKOV M. , TATEO R.
Published: October 2004

By using the thermodynamic Bethe ansatz approach, we give evidence of the existence of both massive and massless behaviors for the ϕ2,1 perturbation of the M3,5 nonunitary minimal model, thus resolving apparent contradictions in the previous literature. The two behaviors correspond to changing the perturbing bare coupling constant from real values to imaginary ones. Generalizations of this picture to the whole class of nonunitary minimal models Mp,2p±1, perturbed by their least relevant operator, lead to a cascade of flows similar to that of unitary minimal models perturbed by ϕ1,3. Various aspects and generalizations of this phenomenon and the links with the Izergin–Korepin model are discussed.
CANONICAL QUANTIZATION OF THE DEGENERATE WESS–ZUMINO ACTION INCLUDING CHIRAL INTERACTION WITH GAUGE FIELDS
Authors: FROLOV S.A. , SLAVNOV A.A. , SOCHICHIU C.
Published: October 2004

A consistent quantization procedure for the chiral SU(3) gauge model in the presence of the SO(3)-invariant Wess–Zumino action is constructed. The physical content of the model is analyzed. As a simple example the 2D SU(2) gauge model with the degenerate Wess–Zumino action is also considered.
THE q-EUCLIDEAN ALGEBRA Uq(eN) AND THE CORRESPONDING q-EUCLIDEAN LATTICE
Authors: FIORE GAETANO
Published: October 2004

We present the Euclidean Hopf algebra Uq(eN) dual of [Formula: see text] and describe its fundamental Hilbert space representations,6 which turn out to be rather simple “lattice-regularized” versions of the classical ones, in the sense that the spectra of squared momentum components are discrete and the corresponding eigenfunctions normalizable. These representations can be regarded as describing a quantum system consisting of one free particle on the quantum Euclidean space. A suitable notion of the classical limit is introduced, so that we recover the classical continuous spectra and generalized (nonnormalizable) eigenfunctions in that limit.
IMPLICATIONS OF NONUNIVERSAL SOFT MASSES FOR GAUGE COUPLING UNIFICATION
Authors: ALTENDORFER RICHARD , KOBAYASHI TATSUO
Published: October 2004

We study the gauge coupling unification of the minimal supersymmetric standard model with nonuniversal soft scalar and gaugino masses. The unification scale of the gauge couplings is estimated for nonuniversal cases. It is sensitive to the nonuniversality. It turns out that these cases can be combined with the assumption of string unification, which leads to a prediction of sin 2 θW(MZ) and k1, the normalization of the U (1)Y generator. String unification predicts that k1=1.3–1.4. These values have nontrivial implications for string model building. Two-loop corrections are also calculated. Some of these cases exhibit a large discrepancy between experiment and string unification. We calculate string threshold corrections to explain the discrepancy.
PLUGGING THE GAUGE-FIXING INTO THE LAGRANGIAN
Authors: PONS J.M.
Published: October 2004

A complete analysis of the consequences of introducing a set of holonomic gauge-fixing constraints (to fix the dynamics) into a singular Lagrangian is performed. It is shown that in general the dynamical system originating from the reduced Lagrangian erases all the information regarding the first class constraints of the original theory, but retains the second class ones. It is proved that even though the reduced Lagrangian can be singular, it never possesses any gauge freedom. As an application, the example of n·A=0 gauges in electromagnetism is treated in full detail.
SPECTRUM DEGENERACY OF GENERAL (p=2)-PARASUPERSYMMETRIC QUANTUM MECHANICS AND PARASUPERSYMMETRIC TOPOLOGICAL INVARIANTS
Authors: MOSTAFAZADEH ALI
Published: October 2004

A thorough analysis of the general features of (p=2)-parasupersymmetric quantum mechanics is presented. It is shown that for both the Rubakov–Spiridonov (RS) formulation and the Beckers–Debergh (BD) formulation of (p=2)-parasupersymmetric quantum mechanics, the degeneracy structure of the energy spectrum can be derived using the defining parasuperalgebras. Thus the results of this article are independent of the details of the Hamiltonian. In fact, they are valid for arbitrary systems based on arbitrary-dimensional coordinate manifolds. In particular, the RS and BD systems possess identical degeneracy structures. For a subclass of RS (alternatively, BD) systems, a new topological invariant is introduced. This is a counterpart of the Witten index of supersymmetric quantum mechanics.
THE FERMION GENERATION PROBLEM IN THE GUST’S OF THE FREE WORLD SHEET FERMION FORMULATION
Authors: MASLIKOV A.A. , NAUMOV I.A. , VOLKOV G.G.
Published: October 2004

In the framework of the four-dimensional heterotic superstring with free fermions, we investigate the rank 8 grand unified string theories (GUST’s) which contain the SU (3)H gauge family symmetry, and develop some methods for building corresponding string models. We explicitly construct GUST’s with gauge symmetry G= SU (5)× U (1) × [ SU (3)× U (1)]H and G= SO (10)×[ SU (3)× U (1)]H ⊂ SO (16) or E(6)× SU (3)H ⊂ E(8), and consider the full massless spectrum for our string models. As the GUST’s originating from level 1 Kac–Moody algebra (KMA) contain only low-dimensional representations, we consider for the observable gauge symmetry the diagonal subgroup G sym of the rank 16 group G×G ⊂ SO (16)× SO (16) or ⊂ E(8)×E(8). We discuss the possible fermion matter and Higgs sectors in these theories. There has to exist “superweak” light chiral matter [Formula: see text] in the GUST’s under consideration. The understanding of quark and lepton mass spectra and family mixing leaves a possibility for the existence of an unusually low mass breaking scale of the SU (3)H family gauge symmetry (some TeV).
GENERALIZED WEIERSTRASS-ENNEPER INDUCING, CONFORMAL IMMERSIONS, AND GRAVITY
Authors: CARROLL ROBERT , KONOPELCHENKO BORIS
Published: October 2004

Basic quantities related to 2D gravity. such as Polyakov extrinsic action, Nambu-Goto action, geometrical action and the Euler characteristic, are studied using generalized Weierstrass-Enneper (GWE) inducing of surfaces in R3. Connection of the GWE inducing with conformal immersion is made and various aspects of the theory are shown to be invariant under the modified Veselov-Novikov hierarchy of flows. The geometry of [Formula: see text] surfaces (h ~ mean curvature) is shown to be connected with the dynamics of infinite- and finite-dimensional integrable systems. Connections with Liouville-Beltrami gravity are indicated.
MIRROR SYMMETRY AND AN EXACT CALCULATION OF AN (N–2)-POINT CORRELATION FUNCTION ON A CALABI-YAU MANIFOLD EMBEDDED IN CPN−1
Authors: JINZENJI MASAO , NAGURA MASARU
Published: October 2004

We consider an (N–2)-dimensional Calabi-Yau manifold which is defined as the zero locus of the polynomial of degree N (of the Fermat type) in CPN−1 and its mirror manifold. We introduce an (N–2)-point correlation function (generalized Yukawa coupling) and evaluate it both by solving the Picard-Fuchs equation for period integrals in the mirror manifold and by explicitly calculating the contribution of holomorphic maps of degree 1 to the Yukawa coupling in the Calabi-Yau manifold using the method of algebraic geometry. In enumerating the holomorphic curves in the general-dimensional Calabi-Yau manifolds, we extend the method of counting rational curves on the Calabi-Yau three-fold using the Shubert calculus on Gr (2, N). The agreement of the two calculations for the (N–2)-point function establishes “the mirror symmetry at the correlation function level” in the general-dimensional case.
NONCOMMUTATIVE GEOMETRY ON QUANTUM PHASE SPACE
Authors: REUTER M.
Published: October 2004

A noncommutative analog of the classical differential forms is constructed on the phase space of an arbitrary quantum system. The noncommutative forms are universal and are related to the quantum-mechanical dynamics in the same way as the classical forms are related to classical dynamics. They are constructed by applying the Weyl-Wigner symbol map to the differential envelope of the linear operators on the quantum-mechanical Hilbert space. This leads to a representation of the noncommutative forms considered by A. Connes in terms of multiscalar functions on the classical phase space. In an appropriate coincidence limit they define a quantum deformation of the classical tensor fields and both commutative and noncommutative forms can be studied in a unified framework. We interpret the quantum differential forms in physical terms and comment on their possible applications.
THE PROCESSES $ e^+e^- \to \mu^+\mu^- ,\mu ^- \to e^- \bar{\nu}_e \nu_\mu ,\mu ^- \to e^- \gamma $ AND HEAVY NEUTRINO DECAY IN THE MAGNETIC MODEL
Authors: ABAK M. , AYDIN C.
Published: October 2004

Calculating the differential cross section of the process e+e−→µ+µ−, differential decay probabilities of [Formula: see text] and heavy neutrino decays, we investigate the contribution of the transition magnetic moment to these processes in the magnetic model. We find that asymmetry arising from the interference of the electroweak amplitude with a small contribution is a result of the transition magnetic moment in the e+e−→µ+µ− process. We also obtain an upper limit for the transition magnetic moment of the heavy neutrino.
A GEOMETRIC REPRESENTATION FOR THE ABELIAN B-F TERM COUPLED TO NONTOPOLOGICAL FIELDS
Authors: GAITAN ROLANDO , LEAL LORENZO
Published: October 2004

The Abelian B-F term coupled to nontopological dynamical fields is quantized in a path- and surface-dependent representation that generalizes the loop representation. The gauge-invariant sector of the theory is shown to be labeled by equivalence classes of sets of paths and open surfaces that reflect the topological nature of the B-F interaction.
THE TWO-DIMENSIONAL STRINGY BLACK HOLE: A NEW APPROACH AND A NEW EFFECT
Authors: DE VEGA H.J. , MITTELBRUN J. RAMÍREZ , MEDRANO M. RAMÓN , SÁNCHEZ N.
Published: October 2004

The string propagation in the two-dimensional stringy black hole is investigated from a new approach. We completely solve the classical and quantum string dynamics in the Lorentzian and Euclidean regimes. In the Lorentzian case all the physics reduces to a massless scalar particle described by a Klein-Gordon type equation with a singular effective potential. The scattering matrix is found and it reproduces the results obtained by coset CFT techniques. It factorizes into two pieces: an elastic Coulombian amplitude and an absorption part. In both parts, an infinite sequence of imaginary poles in the energy appears. The generic features of string propagation in curved D-dimensional backgrounds (string stretching, fall into space-time singularities) are analyzed in the present case. A new physical phenomenon specific to the present black hole is found: the quantum renormalization of the speed of light. We find that [Formula: see text] where k is the integer in front of the WZW action. Only for k→∞ does this new effect disappear (although the conformal anomaly is present). We analyze all the classical Euclidean string solutions and exactly compute the quantum partition function. No critical Hagedorn temperature appears here.
PROBING LEPTON-NUMBER-VIOLATING COUPLINGS OF DOUBLY-CHARGED HIGGS BOSONS AT AN e−e− COLLIDER
Authors: GUNION JOHN F.
Published: October 2004

The doubly charged Higgs bosons Δ−− that are present in exotic Higgs representations can have lepton-number-violating couplings to e−e−. We discuss general constraints and phenomenology for the Δ−− and demonstrate that extremely small values for the e−e−→Δ−− coupling-squared (some 8 orders of magnitude smaller than the current limit) would produce observable signals for Δ−− production in direct s-channel production at an e−e− collider.
e−e−→W−W− MEDIATED BY HEAVY NEUTRINO FLAVORS
Authors: MINKOWSKI PETER
Published: October 2004

The lepton flavor violating reaction e−e−→W–W–, mediated by a set of heavy neutrino flavors extending minimally the standard model, is dominated at high energy in Born approximation by a single channel amplitude, scattering two left-handed incoming electrons into two outgoing longitudinally polarized standard W bosons. This amplitude depends universally on the Fermi constant and specifically on mass and mixing parameters of heayy neutrino flavors. It satisfies unitarity constraints and, if observed, is capable of revealing the CP-violating character of these parameters as interference patterns between heavy flavor contributions, provided their total number exceeds two. Cross section estimates are presented.
EXTENDED GAUGE MODELS AND e−e−→W−W− AT THE NLC
Authors: RIZZO THOMAS G.
Published: October 2004

We briefly discuss two possible manifestations of the lepton number violating reaction [Formula: see text] which probes the masses and mixings of heavy Majorana neutrinos, at the Next Linear Collider(NLC). Cross sections for this process are shown to be potentially quite large at center of mass energies of order 1–1.5 TeV.
EXPERIMENTATION AT e−e− LINEAR COLLIDERS
Authors: MARKIEWICZ THOMAS W.
Published: October 2004

The design of the interaction region for an e−e− collider will involve an understanding of beam-beam effects, detector backgrounds, and the constraints required to maintain very small beam spot sizes. This paper reviews progress in the design of the e+e− interaction region of the proposed SLAC X-band NLC as a base design for the e−e− detector.
COMMENTS ON THE POSSIBLE USE OF THE SLC AS AN e−e− COLLIDER
Authors: ERICKSON R.
Published: October 2004

In this letter, we discuss practical issues that must be addressed to reconfigure the SLAC Linear Collider as the first multi-GeV e−e− collider.
SPIN POLARIZATION BY EXTERNAL MAGNETIC FIELDS, AHARONOV-BOHM FLUX STRINGS, AND CHIRAL SYMMETRY BREAKING IN QED3
Authors: PARWANI RAJESH R.
Published: October 2004

In the first part, the induced vacuum spin around an Aharonov-Bohm flux string in massless three-dimensional QED is computed explicitly and the result is shown to agree with a general index theorem. A previous observation in the literature, that the presence of induced vacuum quantum numbers which are not periodic in the flux make an integral-flux AB string visible, is reinforced. In the second part, a recent discussion of chiral symmetry breaking by external magnetic fields in parity-invariant QED 3 and its relation to the induced spin in parity-noninvariant QED 3 is further elaborated. Finally, other vacuum polarization effects around flux tubes in different variants of QED, in three and four dimensions are mentioned.
UNIVERSAL ASPECTS OF TWO-DIMENSIONAL YANG-MILLS THEORY AT LARGE N
Authors: CRESCIMANNO MICHAEL , SCHNITZER HOWARD J.
Published: October 2004

We show that the large N partition functions and Wilson loop observables of two-dimensional Yang-Mills theories admit a universal functional form irrespective of the gauge group. We demonstrate that U(N) QCD 2 undergoes a large N, third order phase transition on the projective plane at an area coupling product of π2/2. We use this as a lemma to provide a direct transcription for the partition functions and phase portraits of Yang-Mills theory from the U(N) on RP 2 at large N to the other classical Lie groups on S2. We compute the expectation value of the Wilson loops in the fundamental representation for SO (N) and Sp (N) on the two-sphere. Finally we compare the strong and weak coupling limit of these expressions with those found elsewhere in the literature.