331 research outputs found
One-loop vertex integrals in heavy-particle effective theories
We give a complete analytical computation of three-point one-loop integrals
with one heavy propagator, up to the third tensor rank, for arbitrary values of
external momenta and masses.Comment: 10 pages, Latex, to appear in J. Phys.
Intermittency in Branching Processes
We study the intermittency properties of two branching processes, one with a
uniform and another with a singular splitting kernel. The asymptotic
intermittency indices, as well as the leading corrections to the asymptotic
linear regime are explicitly computed in an analytic framework. Both models are
found to possess a monofractal spectrum with . Relations with
previous results are discussed.Comment: 20 pages, UCLA93/TEP/2
Dependence of on Fermi momentum in ACCMM model
The Gaussian width of Fermi momentum, , is the most important
parameter of the ACCMM model, and its value is essential in the determination
of because the experimental analysis is allowed only at the
end-point region of inclusive semileptonic -decay spectrum. We extract the
value of as a function of . We also calculate the
parameter in the relativistic quark model using the variational
method, and obtain GeV which is much larger than the commonly
used value, GeV, in experimental analyses. When we use GeV instead of 0.3 GeV, the value of from ACCMM model is
increased by a factor 1.81, and can give a good agreement with Isgur {\it et
al.} model.Comment: 1. Section 2 has been revised by considering the fact that in the
real experimental situation the only measured quantity is the number of
events in the high region compared to the total semi- leptonic event
number. 2. The article by C. Greub and D. Wyler (Phys. Lett. B295 (1992) 293)
has been included in references, which reports a similar conclusion for the
value of (=566 MeV), even though they used the different
approach. 3. This article will be published in Z. Phys. C (1995
Baryon polarization in low-energy unpolarized meson-baryon scattering
We compute the polarization of the final-state baryon, in its rest frame, in
low-energy meson--baryon scattering with unpolarized initial state, in
Unitarized BChPT. Free parameters are determined by fitting total and
differential cross-section data (and spin-asymmetry or polarization data if
available) for , and scattering. We also compare our
results with those of leading-order BChPT
B --> pi and B --> K transitions in partially quenched chiral perturbation theory
We study the properties of the B-->pi and B-->K transition form factors in
partially quenched QCD by using the approach of partially quenched chiral
perturbation theory combined with the static heavy quark limit. We show that
the form factors change almost linearly when varying the value of the sea quark
mass, whereas the dependence on the valence quark mass contains both the
standard and chirally divergent (quenched) logarithms. A simple strategy for
the chiral extrapolations in the lattice studies with Nsea=2 is suggested. It
consists of the linear extrapolations from the realistically accessible quark
masses, first in the sea and then in the valence quark mass. From the present
approach, we estimate the uncertainty induced by such extrapolations to be
within 5%.Comment: Published versio
B-->pi and B-->K transitions in standard and quenched chiral perturbation theory
We study the effects of chiral logs on the heavy-->light pseudoscalar meson
transition form factors by using standard and quenched chiral perturbation
theory combined with the static heavy quark limit. The resulting expressions
are used to indicate the size of uncertainties due to the use of the quenched
approximation in the current lattice studies. They may also be used to assess
the size of systematic uncertainties induced by missing chiral log terms in
extrapolating toward the physical pion mass. We also provide the coefficient
multiplying the quenched chiral log, which may be useful if the quenched
lattice studies are performed with very light mesons.Comment: 33 pages, 8 PostScript figures, version to appear in PR
Male breast cancer
Male breast cancer (MBC) is a rare disease representing less than 1% of all breast cancers (BC) and less than 1% of cancers in men. Age at presentation is mostly in the late 60s. MBC is recognized as an estrogen-driven disease, specifically related to hyperestrogenism. About 20% of MBC patients have family history for BC. Mutations in BRCA1 and, predominantly, BRCA2, account for approximately 10% of MBC cases.
Because of its rarity, MBC is often compared with female BC (FBC). Based on age-frequency distribution, age-specific incidence rate patterns and prognostic factors profiles, MBC is considered similar to late-onset, postmenopausal estrogen/progesterone receptor positive (ER+/PR+) FBC. However, clinical and pathological characteristics of MBC do not exactly overlap FBC. Compared with FBC, MBC has been reported to occur later in life, present at a higher stage, and display lower histologic grade, with a higher proportion of ER+ and PR+ tumors.
Although rare, MBC remains a substantial cause for morbidity and mortality in men, probably because of its occurrence in advanced age and delayed diagnosis. Diagnosis and treatment of MBC generally is similar to that of FBC. Men tend to be treated with mastectomy rather than breast-conserving surgery. The backbone of adjuvant therapy or palliative treatment for advanced disease is endocrine, mostly tamoxifen.
Use of FBC-based therapy led to the observation that treatment outcomes for MBC are worse and that survival rates for MBC do not improve like FBC. These different outcomes may suggest a non-appropriate utilization of treatments and that different underlying pathogenetic mechanisms may exist between male and female BC
Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain
A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency of occurrence above 20% in coastal waters. In the results obtained until now, octylphenol, pentachlorobenzene, DEHP and TBT exceeded the annual average concentration (EQS-AAC), and only TBT surpassed the maximum allowable concentration (EQS-MAC). The most frequent contaminants determined in coastal waters were also present in WWTP effluents. (C) 2011 Elsevier Ltd. All rights reserved.Financial support from Conselleria de Medio Ambiente, Agua, Urbanismo y Vivienda de la Generalitat Valenciana (Application of Water Framework Directive 2000/60/EC on endocrine disruptors and priority substances in coastal areas in the Comunidad Valenciana) is gratefully acknowledged.Martà Ortega, N.; Aguado GarcÃa, D.; Segovia MartÃnez, L.; Bouzas Blanco, A.; Seco Torrecillas, A. (2011). Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain. Marine Pollution Bulletin. 62(3):615-625. doi:10.1016/j.marpolbul.2011.01.010S61562562
Molecular characterization of hepatitis B virus X gene in chronic hepatitis B patients
BACKGROUND: HBV-X protein is associated with the pathogenesis of HBV related diseases, specially in hepatocellular carcinomas of chronic patients. Genetic variability of the X gene includes genotypic specific variations and mutations emerging during chronic infection. Its coding sequence overlaps important regions for virus replication, including the basal core promoter. Differences in the X gene may have implications in biological functions of the protein and thus, affect the evolution of the disease. There are controversial results about the consequences of mutations in this region and their relationship with pathogenesis. The purpose of this work was to describe the diversity of HBV-X gene in chronic hepatitis patients infected with different genotypes, according to liver disease. METHODS: HBV-X gene was sequenced from chronic hepatitis B patient samples, analyzed by phylogeny and genotyped. Nucleotide and aminoacid diversity was determined calculating intragenetic distances. Mutations at 127, 130 and 131 aminoacids were considered in relation to liver disease. RESULTS: The most prevalent genotype detected in this cohort was F (F1 and F4), followed by D and A. Most of the samples corresponding to genotypes A and F1 were HBeAg(+) and for genotypes D and F4, HBeAg(−) samples were represented in a higher percentage. Intragenetic distance values were higher in HBeAg(−) than in positive samples for all genotypes, and lower in overlapped regions, compared to single codification ones. Nucleotide and aminoacid diversities were higher in HBeAg(−), than in HBeAg(+) samples. CONCLUSIONS: Independently of the infecting genotypes, mutations at any of 127, 130 and/or 131 aminoacid positions and HBeAg(−) status were associated with mild liver disease in this cohort
from the Hadron Energy Spectrum in Inclusive Semileptonic B Decays
A measurement of the hadron energy spectrum in inclusive semileptonic
decays is proposed as a viable method for extracting . Compared to
the traditional energy spectrum of the charged lepton, the hadron energy
spectrum exhibits kinematical advantages such as a wider energy window and a
larger signal branching fraction. It is emphasized that the hadron energy
spectrum method is most suited for symmetric factories, such as CLEO. The
hadron energy distribution is calculated in the approach of the Altarelli et
al. model and of the heavy-quark effective field theory. In both methods,
perturbative QCD corrections, the Fermi motion of the -quark in the
-meson, and the recoil momentum of the -meson (stemming from the
resonance) are taken into account. We have found excellent
agreement between the spectra calculated in both methods, especially in the
relevant kinematical region below the charmed meson threshold. The theoretical
error to , which is dominated by the uncertainty of the -quark
mass, is estimated to be at the level.Comment: 16 pages, 4 Figures included in the text (uses epsfig.sty), 1 tabl
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