bluuebunny/crossref_metadata_2025 huggingface dataset:
Thin Pilus PilV Adhesins of Plasmid R64 Recognize Specific Structures of the Lipopolysaccharide Molecules of Recipient Cells
Authors: Ishiwa Akiko , Komano Teruya
Published: August 2003

IncI1 plasmid R64 encodes a type IV pilus called a thin pilus, which includes PilV adhesins. Seven different sequences for the C-terminal segments of PilV adhesins can be produced by shufflon DNA rearrangement. The expression of the seven PilV adhesins determines the recipient specificity in liquid matings of plasmid R64.
Salmonella enterica
serovar Typhimurium LT2 was recognized by the PilVA′ and PilVB′ adhesins, while
Escherichia coli
K-12 was recognized by the PilVA′, PilVC, and PilVC′ adhesins. Lipopolysaccharide (LPS) on the surfaces of recipient cells was previously shown to be the specific receptor for the seven PilV adhesins. To identify the specific receptor structures of LPS for various PilV adhesins, R64 liquid matings were carried out with recipient cells consisting of various
S. enterica
serovar Typhimurium LT2 and
E. coli
K-12
waa
mutants and their derivatives carrying various
waa
genes of different origins. From the mating experiments, including inhibition experiments, we propose that the GlcNAc(α1-2)Glc and Glc(α1-2)Gal structures of the LPS core of
S. enterica
serovar Typhimurium LT2 function as receptors for the PilVB′ and PilVC′ adhesins, respectively, while the PilVC′ receptor in the wild-type LT2 LPS core may be masked. We further propose that the GlcNAc(β1-7)Hep and Glc(α1-2)Glc structures of the LPS core of
E. coli
K-12 function as receptors for the PilVC and PilVC′ adhesins, respectively.
Definition of a Second
Bacillus subtilis pur
Regulon Comprising the
pur
and
xpt-pbuX
Operons plus
pbuG
,
nupG
(
yxjA
), and
pbuE
(
ydhL
)
Authors: Johansen Lars Engholm , Nygaard Per , Lassen Catharina , Agersø Yvonne , Saxild Hans H.
Published: August 2003

In
Bacillus subtilis
expression of genes or operons encoding enzymes and other proteins involved in purine synthesis is affected by purine bases and nucleosides in the growth medium. The genes belonging to the PurR regulon (
purR
,
purA
,
glyA
,
guaC
,
pbuO
,
pbuG
, and the
pur
,
yqhZ-folD
, and
xpt-pbuX
operons) are controlled by the PurR repressor, which inhibits transcription initiation. Other genes are regulated by a less-well-described transcription termination mechanism that responds to the presence of hypoxanthine and guanine. The
pur
operon and the
xpt-pbuX
operon, which were studied here, are regulated by both mechanisms. We isolated two mutants resistant to 2-fluoroadenine in which the
pur
operon and the
xpt-pbuX
operon are expressed at increased levels in a PurR-independent manner. The mutations were caused by deletions that disrupted a potential transcription terminator structure located immediately upstream of the
ydhL
gene. The 5′ part of the
ydhL
leader region contained a 63-nucleotide (nt) sequence very similar to the 5′ ends of the leaders of the
pur
and
xpt-pbuX
operons. Transcripts of these regions may form a common tandem stem-loop secondary structure. Two additional genes with potential leader regions containing the 63-nt sequence are
pbuG
, encoding a hypoxanthine-guanine transporter, and
yxjA
, which was shown to encode a purine nucleoside transporter and is renamed
nupG
. Transcriptional
lacZ
fusions and mutations in the 63-nt sequence encoding the possible secondary structures provided evidence that expression of the
pur
and
xpt-pbuX
operons and expression of the
ydhL
,
nupG
, and
pbuG
genes are regulated by a common mechanism. The new
pur
regulon is designated the XptR regulon. Except for
ydhL
, the operons and genes were negatively regulated by hypoxanthine and guanine.
ydhL
was positively regulated. The derived amino acid sequence encoded by
ydhL
(now called
pbuE
) is similar to the amino acid sequences of metabolite efflux pumps. When overexpressed, PbuE lowers the sensitivity to purine analogs. Indirect evidence indicated that PbuE decreases the size of the internal pool of hypoxanthine. This explains why the hypoxanthine- and guanine-regulated genes are expressed at elevated levels in a mutant that overexpresses
pbuE
.
Identification of a Differentially Expressed Oligopeptide Binding Protein (OppA2) in
Streptococcus uberis
by Representational Difference Analysis of cDNA
Authors: Taylor D. L. , Ward P. N. , Rapier C. D. , Leigh J. A. , Bowler L. D.
Published: August 2003

Streptococcus uberis
is an increasingly significant cause of intramammary infection in the dairy cow, presently responsible for approximately 33% of all cases of bovine mastitis in the United Kingdom. Following experimentally induced infection of the lactating mammary gland,
S. uberis
is found predominantly in the luminal areas of secretory alveoli and ductular tissue, indicating that much of the bacterial growth occurs in residual and newly synthesized milk. With the objective of identifying potential virulence determinants in a clinical isolate of
S. uberis
, we have used representational difference analysis of cDNA to identify genes that show modified expression in milk. We have identified a number of differentially expressed genes that may contribute to the overall pathogenicity of the organism. Of these, a transcript encoding a putative oligopeptide binding protein (OppA) was further characterized. We have found that
S. uberis
possesses two
oppA
-like open reading frames,
oppA1
and
oppA2
, which are up-regulated to different degrees following growth in milk. Mutants lacking either
oppA1
or
oppA2
are viable and have an increased resistance to the toxic peptide derivative aminopterin; however, only mutants lacking
oppA1
display a lower rate of growth in milk. In addition, expression of the
oppA
genes appears to be coordinated by different mechanisms. We conclude that the
oppA
genes encode oligopeptide binding proteins, possibly displaying different specificities, required for the efficient growth of
S. uberis
in milk.
Complete Genome Sequence of the Broad-Host-Range Vibriophage KVP40: Comparative Genomics of a T4-Related Bacteriophage
Authors: Miller Eric S. , Heidelberg John F. , Eisen Jonathan A. , Nelson William C. , Durkin A. Scott , Ciecko Ann , Feldblyum Tamara V. , White Owen , Paulsen Ian T. , Nierman William C. , Lee Jong , Szczypinski Bridget , Fraser Claire M.
Published: August 2003

The complete genome sequence of the T4-like, broad-host-range vibriophage KVP40 has been determined. The genome sequence is 244,835 bp, with an overall G+C content of 42.6%. It encodes 386 putative protein-encoding open reading frames (CDSs), 30 tRNAs, 33 T4-like late promoters, and 57 potential rho-independent terminators. Overall, 92.1% of the KVP40 genome is coding, with an average CDS size of 587 bp. While 65% of the CDSs were unique to KVP40 and had no known function, the genome sequence and organization show specific regions of extensive conservation with phage T4. At least 99 KVP40 CDSs have homologs in the T4 genome (Blast alignments of 45 to 68% amino acid similarity). The shared CDSs represent 36% of all T4 CDSs but only 26% of those from KVP40. There is extensive representation of the DNA replication, recombination, and repair enzymes as well as the viral capsid and tail structural genes. KVP40 lacks several T4 enzymes involved in host DNA degradation, appears not to synthesize the modified cytosine (hydroxymethyl glucose) present in T-even phages, and lacks group I introns. KVP40 likely utilizes the T4-type sigma-55 late transcription apparatus, but features of early- or middle-mode transcription were not identified. There are 26 CDSs that have no viral homolog, and many did not necessarily originate from
Vibrio
spp., suggesting an even broader host range for KVP40. From these latter CDSs, an NAD salvage pathway was inferred that appears to be unique among bacteriophages. Features of the KVP40 genome that distinguish it from T4 are presented, as well as those, such as the replication and virion gene clusters, that are substantially conserved.
Topology of RbsC, the Membrane Component of the
Escherichia coli
Ribose Transporter
Authors: Stewart Jeffrey B. , Hermodson Mark A.
Published: August 2003

The topology of RbsC, the membrane component of the ribose transporter in
Escherichia coli
, has been determined by using 34 single-cysteine mutants and a modified fluorescence labeling technique designated multiplex labeling. This technique gives topology, expression, and localization information for a membrane protein from a single batch of bacterial cells. The results indicate that RbsC contains 10 transmembrane-spanning helices, with the N and C termini being in the cytosol. This topology matches predictions from the latest prediction programs and the topology of the similar, recently crystallized membrane protein BtuC.
Yeast Two-Hybrid Studies on Interaction of Proteins Involved in Regulation of Nitrogen Fixation in the Phototrophic BacteriumRhodobacter capsulatus
Authors: Pawlowski Alice , Riedel Kai-Uwe , Klipp Werner , Dreiskemper Petra , Groß Silke , Bierhoff Holger , Drepper Thomas , Masepohl Bernd
Published: August 2003

Rhodobacter capsulatuscontains two PII-like proteins, GlnB and GlnK, which play central roles in controlling the synthesis and activity of nitrogenase in response to ammonium availability. Here we used the yeast two-hybrid system to probe interactions between these PII-like proteins and proteins known to be involved in regulating nitrogen fixation. Analysis of defined protein pairs demonstrated the following interactions: GlnB-NtrB, GlnB-NifA1, GlnB-NifA2, GlnB-DraT, GlnK-NifA1, GlnK-NifA2, and GlnK-DraT. These results corroborate earlier genetic data and in addition show that PII-dependent ammonium regulation of nitrogen fixation inR. capsulatusdoes not require additional proteins, like NifL inKlebsiella pneumoniae. In addition, we found interactions for the protein pairs GlnB-GlnB, GlnB-GlnK, NifA1-NifA1, NifA2-NifA2, and NifA1-NifA2, suggesting that fine tuning of the nitrogen fixation process inR. capsulatusmay involve the formation of GlnB-GlnK heterotrimers as well as NifA1-NifA2 heterodimers. In order to identify new proteins that interact with GlnB and GlnK, we constructed anR. capsulatusgenomic library for use in yeast two-hybrid studies. Screening of this library identified the ATP-dependent helicase PcrA as a new putative protein that interacts with GlnB and the Ras-like protein Era as a new protein that interacts with GlnK.
The Genome Sequence of
Yersinia pestis
Bacteriophage φA1122 Reveals an Intimate History with the Coliphage T3 and T7 Genomes
Authors: Garcia Emilio , Elliott Jeffrey M. , Ramanculov Erlan , Chain Patrick S. G. , Chu May C. , Molineux Ian J.
Published: August 2003

The genome sequence of bacteriophage φA1122 has been determined. φA1122 grows on almost all isolates of
Yersinia pestis
and is used by the Centers for Disease Control and Prevention as a diagnostic agent for the causative agent of plague. φA1122 is very closely related to coliphage T7; the two genomes are colinear, and the genome-wide level of nucleotide identity is about 89%. However, a quarter of the φA1122 genome, one that includes about half of the morphogenetic and maturation functions, is significantly more closely related to coliphage T3 than to T7. It is proposed that the yersiniophage φA1122 recombined with a close relative of the
Y. enterocolitica
phage φYeO3-12 to yield progeny phages, one of which became the classic T3 coliphage of Demerec and Fano (M. Demerec and U. Fano, Genetics
30:
119-136, 1945).
Cloning and Expression of the Gene for a Novel Protein from
Mycobacterium smegmatis
with Functional Similarity to Eukaryotic Calmodulin
Authors: Reddy Prasad T. , Prasad C. Rama , Reddy P. Hemalatha , Reeder Dennis , McKenney Keith , Jaffe Howard , Dimitrova Mariana N. , Ginsburg Ann , Peterkofsky Alan , Murthy P. Suryanarayana
Published: August 2003

A calmodulin-like protein (CAMLP) from
Mycobacterium smegmatis
was purified to homogeneity and partially sequenced; these data were used to produce a full-length clone, whose DNA sequence contained a 55-amino-acid open reading frame.
M. smegmatis
CAMLP, expressed in
Escherichia coli
, exhibited properties characteristic of eukaryotic calmodulin: calcium-dependent stimulation of eukaryotic phosphodiesterase, which was inhibited by the calmodulin antagonist trifluoperazine, and reaction with anti-bovine brain calmodulin antibodies. Consistent with the presence of nine acidic amino acids (16%) in
M. smegmatis
CAMLP, there is one putative calcium-binding domain in this CAMLP, compared to four such domains for eukaryotic calmodulin, reflecting the smaller molecular size (approximately 6 kDa) of
M. smegmatis
CAMLP. Ultracentrifugation and mass spectral studies excluded the possibility that calcium promotes oligomerization of purified
M. smegmatis
CAMLP.
Complete Nucleotide Sequence and Genetic Organization of the 210-Kilobase Linear Plasmid ofRhodococcus erythropolisBD2
Authors: Stecker Christiane , Johann Andre , Herzberg Christina , Averhoff Beate , Gottschalk Gerhard
Published: August 2003

The complete nucleotide sequence of the linear plasmid pBD2 fromRhodococcus erythropolisBD2 comprises 210,205 bp. Sequence analyses of pBD2 revealed 212 putative open reading frames (ORFs), 97 of which had an annotatable function. These ORFs could be assigned to six functional groups: plasmid replication and maintenance, transport and metalloresistance, catabolism, transposition, regulation, and protein modification. Many of the transposon-related sequences were found to flank the isopropylbenzene pathway genes. This finding together with the significant sequence similarities of theipbgenes to genes of the linear plasmid-encoded biphenyl pathway in other rhodococci suggests that theipbgenes were acquired via transposition events and subsequently distributed among the rhodococci via horizontal transfer.
Unique Degradation Signal for ClpCP inBacillus subtilis
Authors: Pan Qi , Losick Richard
Published: August 2003

Regulation of the cell-specific transcription factor σFin the spore-forming bacteriumBacillus subtilisinvolves the antisigma factor SpoIIAB. Contributing to the activation of σFis the degradation of SpoIIAB in a manner that depends on the protease ClpCP. Here we show that the three residues (LCN) located at the extreme C terminus of SpoIIAB are both necessary and sufficient for this degradation. We also report that the use of the LCN extension as a degradation signal for ClpCP is unique to SpoIIAB.
Polynucleotide Phosphorylase-Deficient Mutants ofPseudomonas putida
Authors: Favaro Rebecca , Dehò Gianni
Published: August 2003

In bacteria, polynucleotide phosphorylase (PNPase) is one of the main exonucleolytic activities involved in RNA turnover and is widely conserved. In spite of this, PNPase does not seem to be essential for growth if the organisms are not subjected to special conditions, such as low temperature. We identified the PNPase-encoding gene (pnp) ofPseudomonas putidaand constructed deletion mutants that did not exhibit cold sensitivity. In addition, we found that the transcription pattern ofpnpupon cold shock inP. putidawas markedly different from that inEscherichia coli. It thus appears thatpnpexpression control and the physiological roles in the cold may be different in different bacterial species.
Efflux of Cytoplasmically Acting Antibiotics from Gram-Negative Bacteria: Periplasmic Substrate Capture by Multicomponent Efflux Pumps Inferred from Their Cooperative Action with Single-Component Transporters
Authors: Palmer Michael
Published: August 2003

In gram-negative bacteria, coexpression of single- and multicomponent efflux pumps may result in multiplicative enhancement of the level of resistance against cytoplasmically acting antibiotics. Here, a simple model is presented to show that this cooperative effect can be accounted for only if substrate capture by the multicomponent efflux transporter occurs in the periplasm but not the cytosol.
Inactivation of
ompR
Promotes Precocious Swarming and
flhDC
Expression in
Xenorhabdus nematophila
Authors: Kim Dong-jin , Boylan Brian , George Nicholas , Forst Steven
Published: August 2003

The response regulator OmpR is involved in numerous adaptive responses to environmental challenges. The role that OmpR plays in swarming behavior and swarm-cell differentiation in the symbiotic-pathogenic bacterium
Xenorhabdus nematophila
was examined in this study. Swarming began 4 h sooner in an
ompR
mutant strain than in wild-type cells. Precocious swarming was correlated with elevated expression of
fliC
, early flagellation, and cell elongation. The level of
flhDC
mRNA was elevated during the early period of swarming in the
ompR
strain relative to the level in the wild type. These findings show that OmpR is involved in the temporal regulation of
flhDC
expression and flagellum production and demonstrate that this response regulator plays a role in the swarming behavior of
X. nematophila
.
Purification and Characterization of the Flagellar Basal Body of
Rhodobacter sphaeroides
Authors: Kobayashi K. , Saitoh T. , Shah D. S. H. , Ohnishi K. , Goodfellow I. G. , Sockett R. E. , Aizawa S.-I.
Published: August 2003

Flagellar hook-basal body (HBB) complexes were purified from
Rhodobacter sphaeroides
. The HBB was more acid labile but more heat stable than that of
Salmonella
species, and protein identification revealed that HBB components were expressed only from one of the two sets of flagellar gene clusters on the
R. sphaeroides
genome, under the heterotrophic growth conditions tested here.
High-Frequency Secondary Mutations after Suicide-Driven Allelic Exchange Mutagenesis in Extraintestinal Pathogenic
Escherichia coli
Authors: Johnson James R. , Lockman Hank A. , Owens Krista , Jelacic Srdjan , Tarr Phillip I.
Published: August 2003

Frequent unintended secondary mutations occurred in extraintestinal pathogenic
Escherichia coli
strains CP9, CFT073, and RS218 during suicide plasmid-mediated, putatively specific deletions of
hlyA
,
papG
allele III, and
iha
. Pulsed-field gel electrophoresis and PCR analyses demonstrated genomic alterations and/or unintended loss of defined virulence genes (
papG
, the F7-2
papA
allele,
iutA
,
sat
,
hlyD
, and
cnf
). Caution is warranted when attributing the observed phenotypic changes to the intended mutation.
Bacillus subtilis
Diacylglycerol Kinase (DgkA) Enhances Efficient Sporulation
Authors: Amiteye Samuel , Kobayashi Kazuo , Imamura Daisuke , Hosoya Shigeo , Ogasawara Naotake , Sato Tsutomu
Published: August 2003

The
sn
-1,2-diacylglycerol kinase homologue gene,
dgkA
, is a sporulation gene indispensable for the maintenance of spore stability and viability in
Bacillus subtilis
. After 6 h of growth in resuspension medium, the endospore morphology of the
dgkA
mutant by standard phase-contrast microscopy was normal; however, after 9 h, the endospores appeared mostly dark by phase-contrast microscopy, suggesting a defect in the spores. Moreover, electron microscopic studies revealed an abnormal cortex structure in mutant endospores 6 h after the onset of sporulation, an indication of cortex degeneration. In addition, a significant decrease in the dipicolinic acid content of mutant spores was observed. We also found that
dgkA
is expressed mainly during the vegetative phase. It seems likely that either the DgkA produced during growth prepares the cell for an essential step in sporulation or the enzyme persists into sporulation and performs an essential function.
FNR-Mediated Oxygen-Responsive Regulation of the
nrdDG
Operon of
Escherichia coli
Authors: Boston T. , Atlung T.
Published: August 2003

Transcription of the
nrdDG
operon, which encodes the class III nucleotide reductase, which is only active under anaerobic conditions, was strongly induced after a shift to anaerobiosis. The induction was completely dependent on the transcriptional activator FNR and was independent of the ArcA-ArcB two-component response regulator system. The
nrdD
transcript start site was mapped to a position immediately downstream of two FNR binding sites. Transcription of the other two nucleotide reductase operons,
nrdAB
and
nrdEF
, did not respond to oxygen conditions in a wild-type background, but
nrdAB
expression was increased in the
fnr
mutant under anaerobic conditions.
IS
1999
Increases Expression of the Extended-Spectrum β-Lactamase VEB-1 in
Pseudomonas aeruginosa
Authors: Aubert Daniel , Naas Thierry , Nordmann Patrice
Published: August 2003

The integron-borne
bla
VEB-1
gene encodes an extended-spectrum β-lactamase. This gene was associated mostly with IS
1999
and rarely with an additional IS
2000
element in
Pseudomonas aeruginosa
isolates from Thailand, whereas IS
1999
was only very rarely associated with
bla
VEB-1
in
Enterobacteriaceae
. Expression experiments and promoter study identified promoter sequences in IS
1999
that increased the expression of VEB-1 in
P. aeruginosa
.
Integration Site forStreptomycesPhage φBT1 and Development of Site-Specific Integrating Vectors
Authors: Gregory Matthew A. , Till Rob , Smith Margaret C. M.
Published: August 2003

Despite extensive similarities between the genomes of theStreptomycestemperate phages φC31 and φBT1, theattP-intloci are poorly conserved. Here we demonstrate that φBT1 integrates into a different attachment site than φC31. φBT1attBlies within SCO4848 encoding a 79-amino-acid putative integral membrane protein. Integration vectors based on φBT1 integrase were shown to have a broad host range and are fully compatible with those based on the φC31attP-intlocus.
Plasmid DNA Supercoiling and Survival in Long-Term Cultures of
Escherichia coli
: Role of NaCl
Authors: Conter Annie
Published: August 2003

The relationship between the survival of
Escherichia coli
during long-term starvation in rich medium and the supercoiling of a reporter plasmid (pBR322) has been studied. In aerated continuously shaken cultures,
E. coli
lost the ability to form colonies earlier in rich NaCl-free Luria-Bertani medium than in NaCl-containing medium, and the negative supercoiling of plasmid pBR322 declined more rapidly in the absence of NaCl. Addition of NaCl at the 24th hour restored both viability and negative supercoiling in proportion to the concentration of added NaCl. Addition of ofloxacin, a quinolone inhibitor of gyrase, abolished rescue by added NaCl in proportion to the ofloxacin added. This observation raises the possibility that cells had the ability to recover plasmid supercoiling even if nutrients were not available and could survive during long-term starvation in a manner linked, at least in part, to the topological state of DNA and gyrase activity.
Role for
Salmonella enterica
Enterobacterial Common Antigen in Bile Resistance and Virulence
Authors: Ramos-Morales Francisco , Prieto Ana I. , Beuzón Carmen R. , Holden David W. , Casadesús Josep
Published: August 2003

Passage through the digestive tract exposes
Salmonella enterica
to high concentrations of bile salts, powerful detergents that disrupt biological membranes. Mutations in the
wecD
or
wecA
gene, both of which are involved in the synthesis of enterobacterial common antigen (ECA), render
S. enterica
serovar Typhimurium sensitive to the bile salt deoxycholate. Competitive infectivity analysis of
wecD
and
wecA
mutants in the mouse model indicates that ECA is an important virulence factor for oral infection. In contrast, lack of ECA causes only a slight decrease in
Salmonella
virulence during intraperitoneal infection. A tentative interpretation is that ECA may contribute to
Salmonella
virulence by protecting the pathogen from bile salts.
Assessment and management of pain in infants
Authors: Mathew P J , Mathew J L
Published: September 2003

Infants, including newborn babies, experience pain similarly and probably more intensely than older children and adults. They are also at risk of adverse long term effects on behaviour and development, through inadequate attention towards pain relief in early life. However, the issue of analgesia in young babies has been largely neglected in most clinical settings, despite subjecting them to painful diagnostic and therapeutic procedures. Several therapeutic and preventive strategies, including systemic and local pharmacological and non-pharamacological interventions, are reported to be effective in relieving pain in infants. A judicious application of these interventions, backed by awareness and sensitivity to pain perception, on the part of the caregivers is likely to yield the best results. This article is a review of the mechanisms of pain perception, objective assessment, and management strategies of pain in infants.
Differential Cross-Sections for Higgs Production
Authors: Ravindran V. , Smith J. , van Neerven W. L.
Published: August 2003

We review recent theoretical progress in evaluating higher order QCD corrections to Higgs boson differential distributions at hadron–hadron colliders.
Ratio of Quark Masses in Duality Theories
Authors: Cleaver G. , Tanaka K.
Published: August 2003

We consider N=2 SU(2) Seiberg–Witten duality theory for models with N f =2 and N f =3 quark flavors. We investigate arbitrary large bare mass ratios between two or three quarks at the singular points. For N f =2 we explore large bare mass ratios corresponding to a singularity in the strong coupling region. For N f =3 we determine the location of both strong and weak coupling singularities that produce specific large bare mass ratios.
Fifth Force from Fifth Dimension: A Comparison Between Two Different Approaches
Authors: Dahia F. , Monte E. M. , Romero C.
Published: August 2003

We investigate the dynamics of particles moving in a spacetime augmented by one extra dimension in the context of the induced matter theory of gravity. We examine the appearance of a fifth force as an effect caused by the extra dimension and discuss two different approaches to the fifth force formalism. We then give two simple examples of application of both approaches by considering the case of a Ricci-flat warped-product manifold and a generalized Randall–Sundrum space.
Variation of the Relative Yield of Charged and Neutral B Mesons Across the ϒ(4S) Resonance
Authors: Voloshin M. B.
Published: August 2003

It is shown that the ratio of the production rates of the pairs B+B- and [Formula: see text] should experience a substantial and rapid variation with energy within the width of the ϒ(4S) resonance, crossing the value of one near the center of the resonance. This behavior is due to an interference of the rapidly changing with energy Breit–Wigner phase with the phase introduced in the wave function of charged mesons by their Coulomb interaction.
Landau–Zener Effect in Superfluid Nuclear Systems
Authors: Mirea M.
Published: August 2003

The Landau–Zener effect is generalized for many-body systems with pairing residual interactions. The microscopic equations of motion are obtained and the 14C decay of 223Ra spectroscopic factors are deduced. An asymmetric nuclear shape parametrization given by two intersected spheres is used. The single particle level scheme is determined in the frame of the superasymmetric two-center shell model. The deformation energy is computed in the microscopic–macroscopic approximation. The penetrabilities are obtained within the WKB approximation. The fine structure of the cluster decay analyzed in the frame of this formalism gives a very good agreement with the experimental ratio of partial half-lives for transition to the first excited state and to the ground state.
The Generation of a Non-Ideal Plasma by Shock Compression of High-Porosity SiO2-Aerogel
Authors: Fortov V. E. , Filimonov A. S. , Gryaznov V. K. , Nikolaev D. N. , Ternovoi V. Ya. , Keeler R. N.
Published: August 2003

By use of the shock loading method, non-ideal SiO 2-aerogel plasmas with shock velocity up to 13 km/s and temperatures in the range of 1–2.5 eV have been generated. Temperatures were measured using fast pyrometry techniques and thermodynamic parameters measured and calculated were compared with results of a set of plasma models.
Neutrino Mixing and the Minimal 3-3-1 Model
Authors: Gusso A. , de S. Pires C. A. , Rodrigues da Silva P. S.
Published: August 2003

In the minimal 3-3-1 model charged leptons come in a nondiagonal basis. Moreover, the Yukawa interactions of the model lead to a non-hermitian charged lepton mass matrix. In other words, the minimal 3-3-1 model presents a very complex lepton mixing. In view of this we check rigorously if the possible textures of the lepton mass matrices allowed by the minimal 3-3-1 model can lead or not to the neutrino mixing required by the recent experiments in neutrino oscillation.
On Consistence of Material Coupling in a GL(3, R) Gauge Formulation of Gravity
Authors: Gaitan Rolando
Published: August 2003

A covariant scheme for material coupling with GL (N,R) gauge formulation of gravity is studied. We revisit a known idea of a Yang–Mills type construction, where quadratical power of cosmological constant has to be considered in consistence with vacuum Einstein's gravity. Then, matter coupling with gravity is introduced and some constraints on fields and background appear. Finally, exploring the N=3 case we elucidate that introduction of auxiliary fields decreases the number of these constraints.
Higgs Phenomenon for the Graviton in AdS Space
Authors: Porrati M.
Published: August 2003

In this review, we summarize recent findings that show how standard 4D Einstein gravity coupled to a conformal field theory can become massive in anti de Sitter space. Key ingredients in this phenomenon are nonstandard "transparent" boundary condition given to the CFT fields and the fact that AdS space is not globally hyperbolic, due to the presence of a time-like boundary.
Astrophysics and Particle Physics in Space with the Alpha Magnetic Spectrometer
Authors: Lamanna Giovanni
Published: September 2003

The Alpha Magnetic Spectrometer (AMS) is a high energy particle physics experiment in space scheduled to be installed on the International Space Station (ISS) by 2006 for a three-year mission. After a precursor flight of a prototype detector on board of the NASA Space Shuttle in June 1998, the construction of the detector in its final configuration is started and it will be completed by 2004. The purpose of this experiment is to provide a high statistics measurement of charged particles and nuclei in rigidity range 0.5 GV to few TV and to explore the high-energy (> 1 GeV ) gamma-ray sky. In this paper we describe the detector layout and present an overview of the main scientific goals both in the domain of astrophysics: cosmic-ray origin, age and propagation and the exploration of the most energetic gamma-ray sources; and in the domain of astroparticle: the anti-matter and the dark matter searches.
Quark and Nuclear Matter in the Linear Chiral Meson Model
Authors: Berges J. , Jungnickel D.-U. , Wetterich C.
Published: August 2003

We present an analytical description of the phase transitions from a nucleon gas to nuclear matter and from nuclear matter to quark matter within the same model. The equation of state for quark and nuclear matter is encoded in the effective potential of a linear sigma model. We exploit an exact differential equation for its dependence upon the chemical potential μ associated to conserved baryon number. An approximate solution for vanishing temperature is used to discuss possible phase transitions as the baryon density increases. For a nucleon gas and nuclear matter we find a substantial density enhancement as compared to quark models which neglect the confinement to baryons. The results point out that the latter models are not suitable to discuss the phase diagram at low temperature.
Chiral Condensates in Quark and Nuclear Matter
Authors: Peng G. X. , Chiang H. C. , Ning P. Z. , Lombardo U. , Loewe M.
Published: August 2003

We present a novel treatment of calculating the in-medium quark condensates. The advantage of this approach is that one does not need to make further assumptions on the derivatives of model parameters with respect to the quark current mass. The normally accepted model-independent result in nuclear matter is naturally reproduced. The change of the quark condensate induced by interactions depends on the incompressibility of nuclear matter. When it is greater than 265 MeV, the density at which the condensate vanishes is higher than that from the linear extrapolation. For the chiral condensate in quark matter, a similar model-independent linear behavior is found at lower densities, which means that the decreasing speed of the condensate in quark matter is merely half of that in nuclear matter if the pion-nucleon sigma commutator is six times the average current mass of u and d quarks. The modification due to QCD-like interactions is found to slow the decreasing speed of the condensate, compared with the linear extrapolation.
One-Loop Renormalization of General Noncommutative Yang–Mills Field Model Coupled to Scalar and Spinor Fields
Authors: Buchbinder I. L. , Krykhtin V. A.
Published: August 2003

We study the theory of noncommutative U (N) Yang–Mills field interacting with scalar and spinor fields in the fundamental and the adjoint representations. We include in the action both the terms describing interaction between the gauge and the matter fields and the terms which describe interaction among the matter fields only. Some of these interaction terms have not been considered previously in the context of noncommutative field theory. We find all counterterms for the theory to be finite in the one-loop approximation. It is shown that these counterterms allow to absorb all the divergencies by renormalization of the fields and the coupling constants, so the theory turns out to be multiplicatively renormalizable. In case of 1PI gauge field functions the result may easily be generalized on an arbitrary number of the matter fields. To generalize the results for the other 1PI functions it is necessary for the matter coupling constants to be adapted in the proper way. In some simple cases this generalization for a part of these 1PI functions is considered.
A Quintessence Problem in Self-Interacting Brans–Dicke Theory
Authors: Chakraborty Subenoy , Chakraborty Narayan Chandra , Debnath Ujjal
Published: August 2003

A quintessence scalar field in self-interacting Brans–Dicke theory is shown to give rise to a nondecelerated expansion of the present universe for open, flat and closed models. Along with providing a nondecelerating solution, it can potentially solve the flatness problem too.
From a Mechanical Lagrangian to the Schrödinger Equation: A Modified Version of the Quantum Newton Law
Authors: Bouda A.
Published: August 2003

In the one-dimensional stationary case, we construct a mechanical Lagrangian describing the quantum motion of a nonrelativistic spinless system. This Lagrangian is written as a difference between a function T, which represents the quantum generalization of the kinetic energy and which depends on the coordinate x and the temporal derivatives of x up the third order, and the classical potential V(x). The Hamiltonian is then constructed and the corresponding canonical equations are deduced. The function T is first assumed to be arbitrary. The development of T in a power series together with the dimensional analysis allow us to fix univocally the series coefficients by requiring that the well-known quantum stationary Hamilton–Jacobi equation be reproduced. As a consequence of this approach, we formulate the law of the quantum motion representing a new version of the quantum Newton law. We also analytically establish the famous Bohm relation [Formula: see text] outside the framework of the hydrodynamical approach and show that the well-known quantum potential, although it is a part of the kinetic term, plays really the role of an additional potential as assumed by Bohm.
Toward Solving the Cosmological Constant Problem?
Authors: Corradini Olindo , Iglesias Alberto , Kakushadze Zurab
Published: August 2003

We discuss the cosmological constant problem in the context of higher codimension brane world scenarios with infinite-volume extra dimensions. In particular, by adding higher curvature terms in the bulk action we are able to find smooth solutions with the property that the four-dimensional part of the brane world-volume is flat for a range of positive values of the brane tension.
On the Emergence of the Microcanonical Description from a Pure State
Authors: Hari Dass N. D. , Kalyana Rama S. , Sathiapalan B.
Published: August 2003

We study, in general terms, the process by which a pure state can "self-thermalize" and appear to be described by a microcanonical density matrix. This requires a quantum mechanical version of the Gibbsian coarse graining that conceptually underlies classical statistical mechanics. We make use of some extra degrees of freedom that are necessary for this. Interaction between these degrees and the system can be understood as a process of resonant absorption and emission of "soft quanta." This intuitive picture allows one to state a criterion for when self thermalization occurs. This paradigm also provides a method for calculating the thermalization rate using the usual formalism of atomic physics for calculating decay rates. We contrast our prescription for coarse graining, which is somewhat dynamical, with the earlier approaches that are intrinsically kinematical. An important motivation for this study is the black hole information paradox.
Quarkonia-Glueball Structure of the Ground Pseudoscalar Mesons
Authors: Li De-Min , Ma Bing , Yu Hong
Published: August 2003

Considering corrections due to SU(3) flavor symmetry breaking, non-ideal ω - ϕ mixing, double OZI and electromagnetic amplitudes of J/ψ decays into a vector and a pseudo-scalar meson, and three-gluon-annihilation amplitudes of radiative decays of J/ψ into a pseudoscalar meson, we investigate two-photon decays of pseudoscalar mesons, radiative decays between pseudoscalar and vector mesons, decays of J/ψ into a vector and a pseudoscalar meson, and radiative decays of J/ψ into a pseudoscalar meson. The quarkonia-glueball structure of η, η′ and η(1440) is phenomenologically deduced from the fit to the updated world average data concerning the above mentioned decays. We find that η (η′) contains about 48.7%, 47.6%, 3.7% (32.9%, 48.8%, 18.3%) non-strange quarkonium, strange quarkonium and glueball components, respectively, and that η(1410) is mainly a glueball state (about 78% glueball component), mixed with 18.5% non-strange quarkonium and 3.5% strange quarkonium. We predict that Br (J/ψ→γη) : Br (J/ψ→γη′) : Br (J/ψ→γη(1410)) = 1.0:5.2:8.0, which can be tested at BEPC/BES with 50 million J/ψ events.
Seiberg–Witten Map for Noncommutative Super Yang–Mills Theory
Authors: Putz V. , Wulkenhaar R.
Published: August 2003

In this paper we derive the Seiberg–Witten map for noncommutative super Yang–Mills theory in Wess–Zumino gauge. Following (and using results of) hep-th/0108045 we split the observer Lorentz transformations into a covariant particle Lorentz transformation and a remainder which gives directly the Seiberg–Witten differential equations. These differential equations lead to a θ-expansion of the noncommutative super Yang–Mills action which is invariant under commutative gauge transformations and commutative observer Lorentz transformation, but not invariant under commutative supersymmetry transformations: The θ-expansion of noncommutative supersymmetry leads to a θ-dependent symmetry transformation. For this reason the Seiberg–Witten map of super Yang–Mills theory cannot be expressed in terms of superfields.
Vacuum Polarization by a Magnetic Flux of Special Cylindric Form
Authors: Drozdov I.
Published: August 2003

We consider the ground state energy of a spinor field in the background of a square well-shaped magnetic flux tube. We use the zeta-function regularization and express the ground state energy as an integral involving the Jost function of a two-dimensional scattering problem. We perform the renormalization by subtracting the contributions from first several heat kernel coefficients. The ground state energy is presented as a convergent expression suited for numerical evaluation. We discuss corresponding numerical calculations. Using the uniform asymptotic expansion of the special functions entering the Jost function we are able to calculate higher order heat kernel coefficients.
Logarithmic Corrections to the FRW Brane Cosmology from 5d Schwarzschild–de Sitter Black Hole
Authors: Nojiri Shin'ichi , Odintsov Sergei D. , Ogushi Sachiko
Published: August 2003

Thermodynamics of 5d SdS black hole is considered. Thermal fluctuations define the (sub-dominant) logarithmic corrections to black hole entropy and then to Cardy–Verlinde formula and to FRW brane cosmology. We demonstrate that logarithmic terms (which play the role of effective cosmological constant) change the behavior of 4d spherical brane in dS, SdS or Nariai bulk. In particularly, bounce Universe occurs or 4d dS brane expands to its maximum and then shrinks. The entropy bounds are also modified by next-to-leading terms. Out of braneworld context the logarithmic terms may suggest slight modification of standard FRW cosmology.
Optimal Renormalization-Group Improvement of R(s) via the Method of Characteristics
Authors: Elias V. , McKeon D. G. C. , Steele T. G.
Published: August 2003

We discuss the application of the method of characteristics to the renormalization-group equation for the perturbative QCD series within the electron–positron annihilation cross-section. We demonstrate how one such renormalization-group improvement of this series is equivalent to a closed-form summation of the first four towers of renormalization-group accessible logarithms to all orders of perturbation theory.
Deformed Exterior Algebra, Quons and their Coherent States
Authors: El Baz M. , Hassouni Y.
Published: August 2003

We review the notion of the deformation of the exterior wedge product. This allows us to construct the deformation of the algebra of exterior forms over a vector space and also over an arbitrary manifold. We relate this approach to the generalized statistics. We study quons, as a particular case of these generalized statistics. We also give their statistical properties.

A large part of the work is devoted to the problem of constructing coherent states for the deformed oscillators. We give a review of all the approaches existing in the literature concerning this point and enforce it with many examples.
Twisted Sectors and Chern–Simons Terms in M-Theory Orbifolds
Authors: Faux Michael , Lüst Dieter , Ovrut Burt A.
Published: August 2003

It is shown that the twisted sector spectrum, as well as the associated Chern–Simons interactions, can be determined on M-theory orbifold fixed planes that do not admit gravitational anomalies. This is demonstrated for the seven-planes arising within the context of an explicit R6 × S1/Z2 × T4/Z2 orbifold, although the results are completely general. Local anomaly cancellation in this context is shown to require fractional anomaly data that can only arise from a twisted sector on the seven-planes, thus determining the twisted spectrum up to a small ambiguity. These results open the door to the construction of arbitrary M-theory orbifolds, including those containing fixed four-planes which are of phenomenological interest.
An M-Theory Perspective on Heterotic K3 Orbifold Compactifications
Authors: Faux Michael , Lüst Dieter , Ovrut Burt A.
Published: August 2003

We analyze the structure of heterotic M-theory on K3 orbifolds by presenting a comprehensive sequence of M-theoretic models constructed on the basis of local anomaly cancellation. This is facilitated by extending the technology developed in our previous papers to allow one to determine "twisted" sector states in nonprime orbifolds. These methods should naturally generalize to four-dimensional models, which are of potential phenomenological interest.
Classical Solution of the Wave Equation
Authors: Sergeenko M. N.
Published: August 2003

The classical limit of wave quantum mechanics is analyzed. It is shown that the basic requirements of continuity and finiteness to the solution of the form ψ(x) = Aei ϕ (x) + Be-i ϕ (x), where [Formula: see text] and W(x) is the reduced classical action of the physical system, give the asymptote of the wave equation and general quantization condition for the action W(x), which yields the exact eigenvalues of the system.
Nonrelativistic Charged Particle-Magnetic Monopole Scattering in the Global Monopole Background
Authors: Cavalcanti de Oliveira A. L. , Bezerra de Mello E. R.
Published: August 2003

We analyze the nonrelativistic quantum scattering problem of a charged particle by an Abelian magnetic monopole in the background of a global monopole. In addition to the magnetic and geometric effects, we consider the influence of the electrostatic self-interaction on the charged particle. Moreover, for the specific case where the electrostatic self-interaction becomes attractive, the charged particle-monopole bound system can be formed and the respective energy spectrum is a hydrogen-like one.
Spatiotemporal Complexities at the Subnuclear Level of Matter
Authors: Meng Ta-Chung
Published: August 2003

It is pointed out that concepts and methods in Sciences of Complex Systems, especially those used in Finance and Economics and those closely related to Self-Organized Criticality (SOC) and/or Avalanche Dynamics are very useful in analyzing and in understanding phenomena at the subnuclear level of matter. A brief summary of the obtained results is presented in this talk: (A) Experimental evidences and theoretical arguments are given which show that spatiotemporal complexities in form of color-singlet gluon-clusters can be formed in hadrons as a consequence of SOC in systems of interacting soft gluons, and that the properties of such complexities can be probed experimentally by examining inelastic diffractive scattering. Simple analytical expressions for inelastic diffractive cross sections d2σ/dt d(Mx2/s) and dσ/dt are derived which are in good agreement with data. (B) It is shown that the existence of SOC in systems of gluons and quarks can be used, not only in probing the possible compositeness of quarks, but also in obtaining direct evidence for, or against, the existence of critical temperature and/or critical chemical potential in quark–gluon systems when hadrons are squeezed together. (C) It is observed that the fluctuations in rapidity distributions in the cosmic-ray data have much in common with the fluctuations associated with stock exchange. This conclusion is reached through a systematic data-analysis where detailed comparisons between the relevant quantities/distributions have been made. The striking similarity seems to suggest that they are complex phenomena of the same (fractal) nature.
Unique Physics Probes Using e- e-, e- γ and γγ Colliders
Authors: Gunion John F.
Published: August 2003

We summarize some of the unique physics capabilities of a e- e- collider and its companion facilities for e- γ and γγ collisions.
Slepton Flavor Physics at Linear Colliders
Authors: Dine Michael , Grossman Yuval , Thomas Scott
Published: August 2003

If low energy supersymmetry is realized in nature it is possible that a first generation linear collider will only have access to some of the superpartners with electroweak quantum numbers. Among these, sleptons can provide sensitive probes for lepton flavor violation through potentially dramatic lepton violating signals. Theoretical proposals to understand the absence of low energy quark and lepton flavor changing neutral currents are surveyed and many are found to predict observable slepton flavor violating signals at linear colliders. The observation or absence of such sflavor violation will thus provide important indirect clues to very high energy physics. Previous analyses of slepton flavor oscillations are also extended to include the effects of finite width and mass differences.