5,302 research outputs found
Topological BF Theories in 3 and 4 Dimensions
In this paper we discuss topological BF theories in 3 and 4 dimensions.
Observables are associated to ordinary knots and links (in 3 dimensions) and to
2-knots (in 4 dimensions). The vacuum expectation values of such observables
give a wide range of invariants. Here we consider mainly the 3-dimensional
case, where these invariants include Alexander polynomials, HOMFLY polynomials
and Kontsevich integrals.Comment: 25 pages, latex, no figures. Transmission problems have been solve
A Generalization of Chetaev's Principle for a Class of Higher Order Non-holonomic Constraints
The constraint distribution in non-holonomic mechanics has a double role. On
one hand, it is a kinematic constraint, that is, it is a restriction on the
motion itself. On the other hand, it is also a restriction on the allowed
variations when using D'Alembert's Principle to derive the equations of motion.
We will show that many systems of physical interest where D'Alembert's
Principle does not apply can be conveniently modeled within the general idea of
the Principle of Virtual Work by the introduction of both kinematic constraints
and variational constraints as being independent entities. This includes, for
example, elastic rolling bodies and pneumatic tires. Also, D'Alembert's
Principle and Chetaev's Principle fall into this scheme. We emphasize the
geometric point of view, avoiding the use of local coordinates, which is the
appropriate setting for dealing with questions of global nature, like
reduction.Comment: 27 pages. Journal of Mathematical Physics (to zappear
Suppression of Dimer Correlations in the Two-Dimensional - Heisenberg Model: an Exact Diagonalization Study
We present an exact diagonalization study of the ground state of the
spin-half model. Dimer correlation functions and the susceptibility
associated to the breaking of the translational invariance are calculated for
the and the clusters. These results -- especially when
compared to the one dimensional case, where the occurrence of a dimerized phase
for large enough frustration is well established -- suggest either a
homogeneous spin liquid or, possibly, a dimerized state with a rather small
order parameter
Use of complementary and alternative medicine (CAM) in cancer patients. An italian multicenter survey
INTRODUCTION:
Complementary and Alternative Medicine (CAM) include a wide range of products (herbs, vitamins, minerals, and probiotics) and medical practices, developed outside of the mainstream Western medicine. Patients with cancer are more likely to resort to CAM first or then in their disease history; the potential side effects as well as the costs of such practices are largely underestimated.
PATIENTS AND METHOD:
We conducted a descriptive survey in five Italian hospitals involving 468 patients with different malignancies. The survey consisted of a forty-two question questionnaire, patients were eligible if they were Italian-speaking and receiving an anticancer treatment at the time of the survey or had received an anticancer treatment no more than three years before participating in the survey.
RESULTS:
Of our patients, 48.9% said they use or have recently used CAM. The univariate analysis showed that female gender, high education, receiving treatment in a highly specialized institute and receiving chemotherapy are associated with CAM use; at the multivariate analysis high education (Odds Ratio, (OR): 1.96 95% Confidence Interval, CI, 1.27-3.05) and receiving treatment in a specialized cancer center (OR: 2.75 95% CI, 1.53-4.94) were confirmed as risk factors for CAM use.
CONCLUSION:
Roughly half of our patients receiving treatment for cancer use CAM. It is necessary that health professional explore the use of CAM with their cancer patients, educate them about potentially beneficial therapies in light of the limited available evidence of effectiveness, and work towards an integrated model of health-care provision
Study of shock waves generation, hot electron production and role of parametric instabilities in an intensity regime relevant for the shock ignition
We present experimental results at intensities relevant to Shock Ignition
obtained at the sub-ns Prague Asterix Laser System in 2012 . We studied shock waves
produced by laser-matter interaction in presence of a pre-plasma. We used a first beam at
1ω (1315 nm) at 7 × 10 13 W/cm 2 to create a pre-plasma on the front side of the target and
a second at 3ω (438 nm) at ∼ 10 16 W/cm 2 to create the shock wave. Multilayer targets
composed of 25 (or 40 μm) of plastic (doped with Cl), 5 μm of Cu (for Kα diagnostics)
and 20 μm of Al for shock measurement were used. We used X-ray spectroscopy of Cl
to evaluate the plasma temperature, Kα imaging and spectroscopy to evaluate spatial and
spectral properties of the fast electrons and a streak camera for shock breakout measurements.
Parametric instabilities (Stimulated Raman Scattering, Stimulated Brillouin Scattering and
Two Plasmon Decay) were studied by collecting the back scattered light and analysing its
spectrum. Back scattered energy was measured with calorimeters. To evaluate the maximum
pressure reached in our experiment we performed hydro simulations with CHIC and DUED
codes. The maximum shock pressure generated in our experiment at the front side of the
target during laser-interaction is 90 Mbar. The conversion efficiency into hot electrons was
estimated to be of the order of ∼ 0.1% and their mean energy in the order ∼50 keV.
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributio
SEOM clinical guideline for the diagnosis and treatment of gastric cancer (GC) and gastroesophageal junction adenocarcinoma (GEJA) (2019)
Gastric cancer (GC) is the fifth most common cancer worldwide with a varied geographic distribution and an aggressive behavior. In Spain, it represents the sixth cause of cancer death. In Western countries, the incidence is decreasing slightly, with an increase in gastroesophageal junction adenocarcinoma (GEJA), a different entity that we separate specifically in the guideline. Molecular biology advances have been done recently, but do not yet lead to the choice in treatment approach except in advanced disease with overexpression of HER2. Endoscopic resection in very early stage, perioperative chemotherapy in locally advanced tumors and preliminary immune therapy resulting in advanced disease are the main treatment innovations in the GC/GEJA treatment. We describe the different evidences and recommendations following the statements of the American College of Physicians
Programmable models of growth and mutation of cancer-cell populations
In this paper we propose a systematic approach to construct mathematical
models describing populations of cancer-cells at different stages of disease
development. The methodology we propose is based on stochastic Concurrent
Constraint Programming, a flexible stochastic modelling language. The
methodology is tested on (and partially motivated by) the study of prostate
cancer. In particular, we prove how our method is suitable to systematically
reconstruct different mathematical models of prostate cancer growth - together
with interactions with different kinds of hormone therapy - at different levels
of refinement.Comment: In Proceedings CompMod 2011, arXiv:1109.104
The gradient flow running coupling with twisted boundary conditions
We study the gradient flow for Yang-Mills theories with twisted boundary
conditions. The perturbative behavior of the energy density is used to define a running coupling at a scale given by the
linear size of the finite volume box. We compute the non-perturbative running
of the pure gauge coupling constant and conclude that the technique is
well suited for further applications due to the relatively mild cutoff effects
of the step scaling function and the high numerical precision that can be
achieved in lattice simulations. We also comment on the inclusion of matter
fields.Comment: 27 pages. LaTe
Higgs decay with monophoton + MET signature from low scale supersymmetry breaking
We study the decay of a standard model-like Higgs boson into a gravitino and
a neutralino, which subsequently decays promptly into another gravitino and a
photon. Such a decay can be important in scenarios where the supersymmetry
breaking scale is of the order of a few TeV, and in the region of low
transverse momenta of the photon, it may provide the dominant contribution to
the final state with a photon and two gravitinos. We estimate the relevant
standard model backgrounds and the prospects for discovering this Higgs decay
through a photon and missing transverse energy signal at the LHC in terms of a
simplified model. We also give an explicit model with manifest, but
spontaneously broken, supersymmetry in which the usual MSSM soft terms are
promoted to supersymmetric operators involving a dynamical goldstino
supermultiplet. This model can give rise to a SM-like CP-even neutral Higgs
particle with a mass of 125 GeV, without requiring substantial radiative
corrections, and with couplings sufficiently large for a signal discovery
through the above mentioned Higgs decay channel with the upcoming data from the
LHC.Comment: 28 pages, 5 figures, 4 tables; v2: updated to JHEP version,
references adde
Conversion of the Mycotoxin Patulin to the Less Toxic Desoxypatulinic Acid by the Biocontrol Yeast Rhodosporidium kratochvilovae Strain LS11
Se describe en este artículo el descubrimiento de la degradación de la micotoxina patulina por una levaduraThe infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived
products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial
microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic
incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the
mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the
biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by
nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After
R. kratochvilovae LS11 had been incubated in the presence of 13C-labeled patulin, label was traced to desoxypatulinic acid, thus
proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than
patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The
lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional
groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway
that is also a detoxification process
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