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Search Results: 1 - 10 of 55633 matches for " David Gomez "
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Changes in Human Hair Induced by UV- and Gamma Irradiation  [PDF]
Ervin Palma, David Gomez, Eugene Galicia, Viktor Stolc, Yuri Griko
Advances in Bioscience and Biotechnology (ABB) , 2016, DOI: 10.4236/abb.2016.71003
Abstract: The effect of UV- and 137Cs gamma radiation on the structural and chemical integrity of human hair was studied to determine the feasibility of using human hair as a non-invasive biomarker of radiation exposure to ionized gamma- and non-ionized UV-radiation. Steady state tryptophan (Trp) fluorescence and chemical analytical methods were used to evaluate the molecular integrity of Trp fluorophores and SH-groups in hair proteins and to assess the radiation induced damage quantitatively. It was found that human hair fibers were progressively damaged by exposure to both UV- and ionized gamma radiation. Damage to the hair was evidenced by a decrease in the fluorescence intensity as a result of observed depletion of the amino acid tryptophan as well as significant reduction in a number of free SH-groups in hair proteins. Hair damage was dose-dependent for exposures between 0 and 10.0 Gy and 0 - 20 J/cm2 of UV-radiation. Additional results demonstrate that hair-fibers exposed to gamma rays, with much higher quantum energy than UV, undergo a smaller extent of changes in Trp fluorescence than when exposed to lower or equal energy of UV-irradiation. The stable Trp fluorophore appears to be extremely sensitive to UV-radiation in contrast to the ionized gamma radiation whose damage is originated from the reaction of free radicals and direct deposition of energy. We conclude that fluorescence spectroscopy represents a useful tool in the quantitative evaluation of the radiation exposure and could also be used for the rapid and non-invasive assessment of radiation dose i.e. biodosimeter. The approach is simple, non-invasive and appears to have considerable potential that enables quantitative evaluation of radiation dose exposure in a single hair fiber.
Bridging knowledge: reflections on crossing the boundaries between long-term care and support
David McDaid,Alarcos Cieza,Ana Rico Gomez
International Journal of Integrated Care , 2009,
Methicillin-Resistant Staphylococcus aureus SCCmec Type and Its Association with Clinical Presentation, Severity, and Length of Stay among Patients with Complicated Skin and Skin Structure Infections  [PDF]
Eric Gomez, Tom Chiang, Patricia A. Hogan, Daniela E. Myers, David B. Huang
Advances in Infectious Diseases (AID) , 2014, DOI: 10.4236/aid.2014.42017

Data from a prospective, randomized, open-label, active-controlled, multicenter, Phase 4 study comparing oral or intravenous linezolid with intravenous vancomycin for treatment of complicated skin and soft-tissue infections caused by methicillin resistant Staphylococcus aureus was used to determine the association between staphylococcal cassette chromosome mec (SCCmec) type and patient’s clinical presentation, infection severity, intravenous therapy duration and length of stay (LOS). Compared to SCCmec types I, II, and III, SCCmec type IV, PVL+ was associated with more frequent presentation of abscesses, lower severity scores, and shorter intravenous therapy duration and LOS in both treatment groups.

Two novel classes of solvable many-body problems of goldfish type with constraints
Francesco Calogero,David Gomez-Ullate
Physics , 2007, DOI: 10.1088/1751-8113/40/20/007
Abstract: Two novel classes of many-body models with nonlinear interactions "of goldfish type" are introduced. They are solvable provided the initial data satisfy a single constraint (in one case; in the other, two constraints): i. e., for such initial data the solution of their initial-value problem can be achieved via algebraic operations, such as finding the eigenvalues of given matrices or equivalently the zeros of known polynomials. Entirely isochronous versions of some of these models are also exhibited: i.e., versions of these models whose nonsingular solutions are all completely periodic with the same period.
Asymptotically isochronous systems
Francesco Calogero,David Gomez-Ullate
Physics , 2007, DOI: 10.2991/jnmp.2008.15.4.5
Abstract: Mechanisms are elucidated underlying the existence of dynamical systems whose generic solutions approach asymptotically (at large time) isochronous evolutions: all their dependent variables tend asymptotically to functions periodic with the same fixed period. We focus on two such mechanisms, emphasizing their generality and illustrating each of them via a representative example. The first example belongs to a recently discovered class of integrable indeed solvable many-body problems. The second example consists of a broad class of (generally nonintegrable) models obtained by deforming appropriately the well-known (integrable and isochronous) many-body problem with inverse-cube two-body forces and a one-body linear ("harmonic oscillator") force.
Dynamical systems on infinitely sheeted Riemann surfaces
Yuri N. Fedorov,David Gomez-Ullate
Physics , 2006, DOI: 10.1016/j.physd.2007.02.001
Abstract: This paper is part of a program that aims to understand the connection between the emergence of chaotic behaviour in dynamical systems in relation with the multi-valuedness of the solutions as functions of complex time $\tau$. In this work we consider a family of systems whose solutions can be expressed as the inversion of a single hyperelliptic integral. The associated Riemann surface ${\mathcal R}$ is known to be an infinitely sheeted covering of the complex time plane, ramified at an infinite set of points whose projection in the $\tau$-plane is dense. The main novelty of this paper is that the geometrical structure of these infinitely sheeted Riemann surfaces is described in great detail, which allows to study global properties of the flow such as asymptotic behaviour of the solutions, periodic orbits and their stability or sensitive dependence on initial conditions. The results are then compared with a numerical integration of the equations of motion. Following the recent approach of Calogero, the real time trajectories of the system are given by paths on $\mathcal R$ that are projected to a circle on the complex plane $\tau$. Due to the branching of $\mathcal R$, the solutions may have different periods or may not be periodic at all.
Sources of stochasticity in constitutive and autoregulated gene expression
Rahul Marathe,David Gomez,Stefan Klumpp
Quantitative Biology , 2012, DOI: 10.1088/0031-8949/2012/T151/014068
Abstract: Gene expression is inherently noisy as many steps in the read-out of the genetic information are stochastic. To disentangle the effect of different sources of stochasticity in such systems, we consider various models that describe some processes as stochastic and others as deterministic. We review earlier results for unregulated (constitutive) gene expression and present new results for a gene controlled by negative autoregulation with cell growth modeled by linear volume growth.
Villareal Carlos,Buelvas David,Moron Lina,Gomez Esperanza
Investigaciones Andina , 2008,
Abstract: Antecedents: whooping cough is an acute respiratory disease that is highly contagious, particularly within confined areas such as family units or shared domestic spaces. In February 2008 an outbreak of whooping cough was reported and cases of the respiratory illness corroborated by epidemiological analysis. Of these cases a certain number had not received a certified vaccine, in addition to which they lacked the sufficient clinical and epidemiological detail to determine the nature of the illness. Methods: a field study of a cross section of the population was undertaken. The nature of the case was confirmed in the laboratory and by epidemiological analysis. At the same time an eradication plan was implemented at an institutional and national level, a policy of mass vaccination was instigated and a process for monitoring the coverage of the vaccinations across the population was rapidly introduced. Chemical prophylactic antidotes were also introduced. Results: one case was confirmed by the laboratory and 4 by epidemiological analysis. The incubation period was established at =16.2 days; the total households affected was 33% (5/15). Of the 52 houses visited 42 were declared safe, there was no sign of child absenteeism in the institutions visited and 100% coverage was recorded across the state. Of the 24170 cases that were registered and attended to, 3227 had compatible diagnoses, 17 were marked as likely cases of whooping cough and 7 were followed up in investigation. Conclusions: there are difficulties in detecting cases of whooping cough and not enough incidents are reported to SIVIGILA, laboratory diagnosis, which could isolate the bacteria is problematic. It is indispensable that all health institutions raise awareness of the condition and that the resources of the public health laboratories be improved.
A new method for scoring active sweat glands
Gomez David S.,Mariani Urio,Leirner Adolfo A.,Mazzetto Marcelo
Clinics , 2005,
An Extension of Bochner's Problem: Exceptional Invariant Subspaces
David Gomez-Ullate,Niky Kamran,Robert Milson
Physics , 2008, DOI: 10.1016/j.jat.2009.11.002
Abstract: A classical result due to Bochner characterizes the classical orthogonal polynomial systems as solutions of a second-order eigenvalue equation. We extend Bochner's result by dropping the assumption that the first element of the orthogonal polynomial sequence be a constant. This approach gives rise to new families of complete orthogonal polynomial systems that arise as solutions of second-order eigenvalue equations with rational coefficients. The results are based on a classification of exceptional polynomial subspaces of codimension one under projective transformations.
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