449 research outputs found
Addition theorems for spin spherical harmonics. II Results
Based on the results of part I, we obtain the general form of the addition
theorem for spin spherical harmonics and give explicit results in the cases
involving one spin- and one spin- spherical harmonics with ,
1, 3/2, and , 1. We obtain also a fully general addition theorem for
one scalar and one tensor spherical harmonic of arbitrary rank. A variety of
bilocal sums of ordinary and spin spherical harmonics are given in explicit
form, including a general explicit expression for bilocal spherical harmonics
Addition theorems for spin spherical harmonics. I Preliminaries
We develop a systematic approach to deriving addition theorems for, and some
other bilocal sums of, spin spherical harmonics. In this first part we
establish some necessary technical results. We discuss the factorization of
orbital and spin degrees of freedom in certain products of Clebsch-Gordan
coefficients, and obtain general explicit results for the matrix elements in
configuration space of tensor products of arbitrary rank of the position and
angular-momentum operators. These results are the basis of the addition
theorems for spin spherical harmonics obtained in part II
Multiplicity Distributions and Rapidity Gaps
I examine the phenomenology of particle multiplicity distributions, with
special emphasis on the low multiplicities that are a background in the study
of rapidity gaps. In particular, I analyze the multiplicity distribution in a
rapidity interval between two jets, using the HERWIG QCD simulation with some
necessary modifications. The distribution is not of the negative binomial form,
and displays an anomalous enhancement at zero multiplicity. Some useful
mathematical tools for working with multiplicity distributions are presented.
It is demonstrated that ignoring particles with pt<0.2 has theoretical
advantages, in addition to being convenient experimentally.Comment: 24 pages, LaTeX, MSUHEP/94071
Sources of experimental errors in the observation of nanoscale magnetism
It has been recently reported that some non-magnetic materials in bulk state,
exhibit magnetic behavior at the nanscale due to surface and size effects. The
experimental observation of these effects is based on the measurement of very
small magnetic signals. Thus, some spurious effects that are not critical for
bulk materials with large magnetic signals may become important when measuring
small signals (typically below 0.0001 emu). Here, we summarize some sources of
these small magnetic signals that should be considered when studying this new
nanomagnetismComment: 16 pages, 10 figure
Effect of physical activity, nutritional education, and consumption of extra virgin olive oil on lipid, physiological and anthropometric profiles in a pediatric population
BACKGROUND. The aim of this study was to determine the effects of nutritional education and vigorous physical activity on health-related parameters. METHODS. The sample group consisted of 134 children from 5 rurally located schools. Participants were divided between 5 different experimental groups: control group (CG), physical activity group (PA), nutritional education group (NE), combined intervention group (PA+NE), and a combined intervention group with additional substitution of normally used oil for extra virgin olive oil (EVOO; PA+NE+EVOO). The intervention consisted of 60 minute sessions of physical activity held twice a week as well as nutritional education sessions held over 6 months. RESULTS. Students in the groups receiving physical activity reduced their fat percentage and increased their muscle mass post intervention. At post-test the lipid profile improved in all intervention groups. The proportion of macronutrients and dietary cholesterol improved in the groups receiving nutritional education. The post-test comparison showed significantly lower fat percentage, sum of skinfolds and waist circumference in NE relative to CG and PA relative to CG. Diastolic blood pressure and glycaemia were significantly lower in PA+NE+EVOO relative to CG. CONCLUSION. A school-based program consisting of nutritional education or nutritional education plus a physical activity program showed a positive effect on health-related parameters in children
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
The interplay of intrinsic and extrinsic bounded noises in genetic networks
After being considered as a nuisance to be filtered out, it became recently
clear that biochemical noise plays a complex role, often fully functional, for
a genetic network. The influence of intrinsic and extrinsic noises on genetic
networks has intensively been investigated in last ten years, though
contributions on the co-presence of both are sparse. Extrinsic noise is usually
modeled as an unbounded white or colored gaussian stochastic process, even
though realistic stochastic perturbations are clearly bounded. In this paper we
consider Gillespie-like stochastic models of nonlinear networks, i.e. the
intrinsic noise, where the model jump rates are affected by colored bounded
extrinsic noises synthesized by a suitable biochemical state-dependent Langevin
system. These systems are described by a master equation, and a simulation
algorithm to analyze them is derived. This new modeling paradigm should enlarge
the class of systems amenable at modeling.
We investigated the influence of both amplitude and autocorrelation time of a
extrinsic Sine-Wiener noise on: the Michaelis-Menten approximation of
noisy enzymatic reactions, which we show to be applicable also in co-presence
of both intrinsic and extrinsic noise, a model of enzymatic futile cycle
and a genetic toggle switch. In and we show that the
presence of a bounded extrinsic noise induces qualitative modifications in the
probability densities of the involved chemicals, where new modes emerge, thus
suggesting the possibile functional role of bounded noises
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
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