Some Finite Size Effects in Simulations of Glass Dynamics

We present the results of a molecular dynamics computer simulation in which we investigate the dynamics of silica. By considering different system sizes, we show that in simulations of the dynamics of this strong glass former surprisingly large finite size effects are present. In particular we demonstrate that the relaxation times of the incoherent intermediate scattering function and the time dependence of the mean squared displacement are affected by such finite size effects. By compressing the system to high densities, we transform it to a fragile glass former and find that for that system these types of finite size effects are much weaker.Comment: 12 pages of RevTex, 4 postscript figures available from W. Ko

Accidentes laborales en veterinarios rurales

El ejercicio de la Veterinaria está asociado a numerosos riesgos ocupacionales. Los objetivos de este trabajo fueron estimar la frecuencia de veterinarios rurales que tuvieron accidentes laborales (AL), describir tipo de lesión y elementos involucrados, factores asociados y ausencia laboral. Se desarrolló un censo en veterinarios rurales (N= 741) que asistieron a reuniones obligatorias de capacitación continua. La tasa de respuesta a un cuestionario estructurado anónimo fue del 75.8% (n= 562). El análisis de los datos incluyó: χ2, t de Student, correlación de Pearson y regresión logística. El 97,1% había sufrido accidentes durante el ejercicio profesional, el 59,6% había requerido atención médica y el 81,4% padecía alguna dolencia derivada de su trabajo. El 52,1% tuvo al menos un día de ausencia laboral debido a accidentes de trabajo (37,9 ± 51,7 días). Sexo, edad y antigüedad profesional estuvieron significativamente asociados con la ocurrencia de AL in labore. en el análisis bivariante, pero no en el multivariante, probablemente debido al muy bajo número de entrevistados que no sufrieron AL. Algunas características de los profesionales, unida a la especial naturaleza de los pacientes, la existencia de instalaciones inapropiadas para ejercer la práctica clínica en condiciones de campo y la necesidad de trasladarse en vehículos automotores para entrar en contacto con los pacientes pueden contribuir para que esta profesión tenga un alto riesgo laboral

Breakup of 17^{17}F on 208^{208}Pb near the Coulomb barrier

Angular distributions of oxygen produced in the breakup of $^{17}$F incident on a $^{208}$Pb target have been measured around the grazing angle at beam energies of 98 and 120 MeV. The data are dominated by the proton stripping mechanism and are well reproduced by dynamical calculations. The measured breakup cross section is approximately a factor of 3 less than that of fusion at 98 MeV. The influence of breakup on fusion is discussed.Comment: 7 pages, 8 figure

Evaluation of metabolic and biochemical blood parameters in lactating cows with Cystic Ovarian Disease

The aim of the study was to determine and evaluate different blood parameters associated to energetic, protein, mineral and liver metabolic processes together with productive and reproductive parameters in dairy cows of Santa Fe province (Argentina) that were diagnosed with cystic ovarian disease (COD). Lactating Argentine Holstein cows from five dairy herds with spontaneous COD (n= 80) diagnosed by ultrasound and control cows (n= 124) were included in the study. Blood samples were obtained from all cows to determine serum concentrations of: growth hormone, insulin-like growth factor (IGF-1), insulin, aspartate aminotransferase, alkalin phosphatase, gamma glutamiltransferase, albumin, total proteins, albumin: globulin ratio, total and direct bilirrubin, ?-hidroxibutirate, colesterol, glucose, urea, creatinin, calcium, phosphorus and magnesium. Serum concentrations of insulin and IGF-1 were lower (P<0.05) in COD than control cows. No significant differences among groups were observed in any other variables studied, however, the calving to conception interval was higher in cows with COD compared to controls. These results allowed us to conclude that there would be an association between blood concentrations of IGF-1 and insulin and COD that, ultimately, compromise the reproductive performance of the cow.Fil: Cattaneo, L. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Cátedra de Teriogenología. Santa Fe, ArgentinaFil: Barberis, F.C. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Cátedra de Teriogenología. Santa Fe, ArgentinaFil: Stangaferro, M.L. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Cátedra de Teriogenología. Santa Fe, ArgentinaFil: Signorini, M.L. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. ArgentinaFil: Signorini, M.L. CONICET. ArgentinaFil: Ruiz, M.F. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Hospital de Salud Animal. Santa Fe, ArgentinaFil: Zimmermann, R. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Hospital de Salud Animal. Santa Fe, ArgentinaFil: Bo, G.A. Instituto de Reproducción Animal Córdoba (IRAC). ArgentinaFil: Hein, G.J. CONICET - Universidad Nacional del Litoral. Instituto de Ciencias Veterinarias del Litoral (ICiVet-Litoral). Esperanza, ArgentinaFil: Ortega, H.H. CONICET - Universidad Nacional del Litoral. Instituto de Ciencias Veterinarias del Litoral (ICiVet-Litoral). Esperanza, ArgentinaEl objetivo de este trabajo fue determinar y evaluar indicadores bioquímicos sanguíneos asociados a procesos metabólicos energéticos, proteicos, minerales y de funcionalidad hepática, junto con parámetros productivos y reproductivos en vacas lecheras que fueron diagnosticadas con enfermedad quística ovárica (COD) y controles. Se emplearon vacas Holando Argentino en lactancia de 5 rebaños de la provincia de Santa Fe (Argentina) que presentaban COD (n= 80) diagnosticada mediante ultrasonografía y controles clínicamente sanas (n= 124). De las vacas se obtuvo sangre coccígea para determinar las concentraciones séricas de las hormonas de crecimiento (GH), factor de crecimiento similar a la insulina-1 (IGF-1) e insulina, la actividad sérica de AST, FA, GGT y las concentraciones séricas de albúmina, proteínas totales, relación albúmina: globulinas, bilirrubina total y directa, ?-hidroxibutirato, colesterol, glucosa, urea, creatinina, calcio, fósforo y magnesio. Las concentraciones séricas de insulina e IGF-1 fueron menores (P<0,05) en las vacas con COD que en las controles. No se observaron diferencias significativas (P>0,05) entre ambos grupos en las demás variables séricas y productivas evaluadas, sin embargo, el intervalo parto-concepción fue mayor en vacas que presentaron COD. Los resultados nos permitieron concluir que habría una asociación entre los valores séricos de IGF-1 e insulina y la COD, y que ésta comprometería el futuro reproductivo de las vacas

Testing Mode-Coupling Theory for a Supercooled Binary Lennard-Jones Mixture II: Intermediate Scattering Function and Dynamic Susceptibility

We have performed a molecular dynamics computer simulation of a supercooled binary Lennard-Jones system in order to compare the dynamical behavior of this system with the predictions of the idealized version of mode-coupling theory (MCT). By scaling the time $t$ by the temperature dependent $\alpha$-relaxation time $\tau(T)$, we find that in the $\alpha$-relaxation regime $F(q,t)$ and $F_s(q,t)$, the coherent and incoherent intermediate scattering functions, for different temperatures each follows a $q$-dependent master curve as a function of scaled time. We show that during the early part of the $\alpha$-relaxation, which is equivalent to the late part of the $\beta$-relaxation, these master curves are well approximated by the master curve predicted by MCT for the $\beta$-relaxation. This part is also fitted well by a power-law, the so-called von Schweidler law. We show that the effective exponent $b'$ of this power-law depends on the wave vector $q$ if $q$ is varied over a large range. The early part of the $\beta$-relaxation regime does not show the critical decay predicted by MCT. The $q$-dependence of the nonergodicity parameter for $F_{s}(q,t)$ and $F(q,t)$ are in qualitative agreement with MCT. On the time scale of the late $\alpha$-relaxation the correlation functions show a Kohlrausch-Williams-Watt behavior (KWW). The KWW exponent $\beta$ is significantly different from the effective von Schweidler exponent $b'$. At low temperatures the $\alpha$-relaxation time $\tau(T)$ shows a power-law behavior with a critical temperature that is the same as the one found previously for the diffusion constant [Phys. Rev. Lett. {\bf 73}, 1376 (1994)]. The critical exponent of this power-law and the von Schweidler exponent $b'$ fulfill the connection proposed by MCT between these two quantities. We also show that theComment: 28 Pages of REVTEX, Figures available from W. Ko

Trends in methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections: effect of the MRSA "search and isolate" strategy in a hospital in Italy with hyperendemic MRSA

Abstract OBJECTIVE: To evaluate the secular trends in MRSA BSIs after the introduction of a nosocomial MRSA control intervention. DESIGN: Before-after study. SETTING: An 850-bed community hospital with an ICU and vascular surgery, neurosurgery, bone marrow transplantation, and AIDS units. MRSA is endemic at this hospital; the prevalence of methicillin resistance among patients with S. aureus infection is greater than 50%. PATIENTS: Among all inpatients, MRSA BSI was identified, its origin defined, and incidence rates calculated by ward and origin. INTERVENTION: A MRSA control program was implemented based on active surveillance cultures to identify MRSA-colonized patients, followed by isolation using contact precautions. Incidence rates of MRSA BSI during the intervention (i.e., July 1, 1997, to December 31, 2001) and preintervention (i.e., January 1, 1996, to June 30, 1997) periods were compared. RESULTS: Sixty-nine MRSA BSIs were identified. When compared with the preintervention period, the incidence rate of MRSA BSI was reduced from 0.64 to 0.30 per 1000 admissions (RR, 0.46; CI95, 0.25-0.87; P = .02) during the intervention period. The impact was greater in the ICU, with an 89% reduction (RR, 0.11; CI95, 0.01-0.98; P = .03), and for CVC-associated MRSA BSIs, with an 82% decrease (RR, 0.17; CI95, 0.05-0.55; P = .002). Methicillin resistance among S. aureus blood isolates decreased from 46% to 17% (RR, 0.36; CI95, 0.22-0.62; P = .0002). CONCLUSION: A reduction in MRSA bacteremia is achievable through use of the MRSA "search and isolate" intervention even in a hospital with high rates of endemic MRSA