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Search Results: 1 - 10 of 214450 matches for " Pérez-Rubio "
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Charmed Baryon Spectroscopy from lattice QCD for $N_f = 2 + 1$ flavours
Paula Pérez-Rubio
Physics , 2013,
Abstract: In recent years, several charmed baryons have been discovered, with more states likely to be found in the future. We investigate the spectra of singly and doubly charmed baryons on the lattice. The spin J=1/2 and J=3/2 states are calculated for both positive and negative parity.
Non-perturbative running of the coupling from four flavour lattice QCD with staggered quarks
Paula Pérez-Rubio,Stefan Sint
Physics , 2010,
Abstract: Using the Schr\"odinger functional (SF) with a single staggered fermion field we calculate the SF coupling in four-flavour QCD for a wide range of energies and lattice sizes up to $L/a=16$. Preliminary results for the continuum extrapolation of the step-scaling function are presented. To reduce cutoff effects, one-loop ${\rm O}(a)$ improvement has been implemented. Various cross checks are made possible by the use of two independent sets of lattices with either $T=L+a$ or $T=L-a$.
Charmed baryon spectroscopy and light flavour symmetry from lattice QCD
Gunnar Bali,Sara Collins,Paula Pérez-Rubio
Physics , 2015, DOI: 10.1103/PhysRevD.92.034504
Abstract: We determine the ground state and first excited state masses of singly and doubly charmed spin 1/2 and 3/2 baryons with positive and negative parity. Configurations with $N_f=2+1$ non-perturbatively improved Wilson-clover fermions were employed, with the same quark action also being used for the valence quarks, including the charm. The spectrum is calculated for pion masses in the range $M_\pi \sim 259-460$ MeV at a lattice spacing $a\sim 0.075$ fm. Finite volume effects are studied comparing lattices with two different linear spatial extents ($1.8\,{\rm fm}$ and $2.4\,{\rm fm}$). The physical point is approached from the SU(3) limit keeping the flavour averaged light quark mass fixed. The baryon masses are extrapolated using expansions in the strange-light quark mass difference. Most particles fall into the expected SU(3) multiplets with well constrained extrapolations, the exceptions having a possibly more complex internal structure. Overall agreement is found with experiment for the masses and splittings of the singly charmed baryons. As part of the calculation an analysis of the lower lying charmonium, $D$ and $D_s$ spectra was performed in order to assess discretisation errors. The gross spectra are reproduced, including the $D^*_{s0}$, $D_{s1}$ and $D_1$ mesons, while at this single lattice spacing hyperfine splittings come out $10-20$ MeV too low.
Charmed hadron spectroscopy on the lattice for $N_f=2+1$ flavours
Gunnar Bali,Sara Collins,Paula Pérez-Rubio
Physics , 2012, DOI: 10.1088/1742-6596/426/1/012017
Abstract: We study the spectra of charmonia, charmed mesons, singly and doubly charmed baryons using Lattice QCD, with 2+1 flavours of fermions. In the case of mesons, we include higher spin states, while for baryons, both positive and negative parity channels were investigated. By means of the variational method, we were able to extract a clean signal from the correlation functions and information about the excited states.
An O(a) modified lattice set-up of the Schr?dinger functional in SU(3) gauge theory
Paula Pérez-Rubio,Stefan Sint,Shinji Takeda
Physics , 2011,
Abstract: The set-up of the QCD Schr\"odinger functional (SF) on the lattice with staggered quarks requires an even number of points $L/a$ in the spatial directions, while the Euclidean time extent of the lattice, $T/a$, must be odd. Identifying a unique renormalisation scale, $L=T$, is then only possible up to O($a$) lattice artefacts. In this article we study such lattices in the pure SU(3) gauge theory, where we can also compare to the standard set-up. We consider the SF coupling as obtained from the variation of an SU(3) Abelian and spatially constant background field. The O($a$) lattice artefacts can be cancelled by the existing O($a$) boundary counterterm. However, its coefficient, $\ct$, differs at the tree-level from its standard value, so that one first needs to re-determine the induced background gauge field. The perturbative one-loop correction to the coupling allows to determine $\ct$ to one-loop order. A few numerical simulations serve to demonstrate that residual cutoff effects in the step scaling function are small in both cases, $T=L\pm a$ and comparable to the standard case with $T=L$.
Evaluación de la adecuación de las estancias en un hospital de tercer nivel Evaluation of the appropriateness of stays in a third level hospital
A. Pérez-Rubio,S. Santos,F. J. Luquero,S. Tamames
Anales del Sistema Sanitario de Navarra , 2007,
Abstract: Fundamento: The Appropriateness Evaluation Protocol (AEP) se ha mostrado como una herramienta útil para la revisión de la utilización de los recursos hospitalarios. El objetivo de este trabajo es conocer la proporción de ingresos y estancias inadecuadas, así como sus causas, en pacientes hospitalizados en el Hospital Clínico Universitario de Valladolid (HCUV). Material y métodos: Estudio observacional analítico de cohortes retrospectivo. El período de estudio ha sido de un a o (2004). Se seleccionó una muestra de 1.630 ingresos. La definición de caso, las variables de interés y el modelo de recogida de datos se han llevado a cabo conforme al AEP. Se han analizado las principales variables mediante un análisis basal y las posibles relaciones entre ellas. Resultados: El 54% de los ingresos presentaron al menos un día de estancia inadecuada, siendo la tasa de inadecuación global del 34,17%. Entre las causas responsables de la inadecuación, el 68,9% de los ingresos presentaron al menos un criterio englobado dentro de la responsabilidad del médico o del hospital, y el 51,3% debido a retrasos en el desarrollo del estudio o tratamiento. Conclusiones: La utilización de métodos de identificación del uso inapropiado como el AEP presenta aplicaciones tanto en planificación como en gestión hospitalaria, al permitir identificar problemas hospitalarios causantes de demoras, principalmente problemas de tipo organizativo, permitiendo el desarrollo de intervenciones encaminadas a la reducción del uso inapropiado. Background: The Appropriateness Evaluation Protocol (AEP) has proved to be a useful tool for reviewing the utilisation of hospital resources. The aim of this article is to determine the proportion of inappropriate admissions and stays, as well as their causes, in patients hospitalised in the Hospital Clínico Universitario de Valladolid (HCUV). Material and methods: A retrospective, analytical, observational, cohort study. The period of study was one year (2004). A sample of 1,630 admissions was gathered. Case definition, variables of interest and the model of data gathering were carried out in accordance with the AEP. The principal variables were analysed by means of a basal analysis and the possible relations between them. Results: Fifty-four percent of the admissions showed at least one day of inappropriate stay, with the global rate of inappropriateness being 34.17%. Amongst the causes responsible for inappropriateness, 68.9% of admissions showed at least one criterion falling under the responsibility of the doctor or the hospital, and 51.3% were due to dela
Preclinical evaluation of azathioprine plus buthionine sulfoximine in the treatment of human hepatocarcinoma and colon carcinoma
Borja Hernández-Breijo,Jorge Monserrat,Sara Ramírez-Rubio,Eva P Cuevas
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i34.3899
Abstract: AIM: To evaluate the efficacy and the safety of azathioprine (AZA) and buthionine sulfoximine (BSO) by localized application into HepG2 tumor in vivo. METHODS: Different hepatoma and colon carcinoma cell lines (HepG2, HuH7, Chang liver, LoVo, RKO, SW-48, SW-480) were grown in minimal essencial medium supplemented with 10% fetal bovine serum and 1% antibiotic/antimycotic solution and maintained in a humidified 37 °C incubator with 5% CO2. These cells were pretreated with BSO for 24 h and then with AZA for different times. We examined the effects of this combination on some proteins and on cellular death. We also studied the efficacy and the safety of AZA (6 mg/kg per day) and BSO (90 mg/kg per day) in HepG2 tumor growth in vivo using athymic mice. We measured safety by serological markers such as aminotransferases and creatine kinase. RESULTS: The in vitro studies revealed a new mechanism of action for the AZA plus BSO combination in the cancer cells compared with other thiopurines (6-mercaptopurine, 6-methylmercaptopurine, 6-thioguanine and 6-methylthioguanine) in combination with BSO. The cytotoxic effect of AZA plus BSO in HepG2 cells resulted from necroptosis induction in a mitochondrial-dependent manner. From kinetic studies we suggest that glutathione (GSH) depletion stimulates c-Jun amino-terminal kinase and Bax translocation in HepG2 cells with subsequent deregulation of mitochondria (cytochrome c release, loss of membrane potential), and proteolysis activation leading to loss of membrane integrity, release of lactate dehydrogenase and DNA degradation. Some of this biochemical and cellular changes could be reversed by N-acetylcysteine (a GSH replenisher). In vivo studies showed that HepG2 tumor growth was inhibited when AZA was combined with BSO. CONCLUSION: Our studies suggest that a combination of AZA plus BSO could be useful for localized treatment of hepatocellular carcinoma as in the currently used transarterial chemoembolization method.
Evaluación de la adecuación de las estancias en un hospital de tercer nivel
Pérez-Rubio,A.; Santos,S.; Luquero,F. J.; Tamames,S.; Cantón,B.; Castrodeza,J.J.;
Anales del Sistema Sanitario de Navarra , 2007, DOI: 10.4321/S1137-66272007000100003
Abstract: background: the appropriateness evaluation protocol (aep) has proved to be a useful tool for reviewing the utilisation of hospital resources. the aim of this article is to determine the proportion of inappropriate admissions and stays, as well as their causes, in patients hospitalised in the hospital clínico universitario de valladolid (hcuv). material and methods: a retrospective, analytical, observational, cohort study. the period of study was one year (2004). a sample of 1,630 admissions was gathered. case definition, variables of interest and the model of data gathering were carried out in accordance with the aep. the principal variables were analysed by means of a basal analysis and the possible relations between them. results: fifty-four percent of the admissions showed at least one day of inappropriate stay, with the global rate of inappropriateness being 34.17%. amongst the causes responsible for inappropriateness, 68.9% of admissions showed at least one criterion falling under the responsibility of the doctor or the hospital, and 51.3% were due to delays in the development of study or treatment. conclusions: the utilisation of methods of identification of inappropriate use such as aep show applications both in planning and in hospital management, by making it possible to identify hospital problems causing delays, principally problems of an organisational type, making it possible to develop interventions aimed at reducing inappropriate use.
Dise?o e implementación de una red de sensores para la adquisición de variables relacionadas con la vigilancia estructural de puentes
Flórez-Rubio,David Magín; Otálora-Sánchez,Camilo; Páez-Rueda,Carlos Iván;
Ingeniería y Universidad , 2009,
Abstract: this article details the design and implementation of a sensor network for structural surveillance of bridges. such network was piloted at the césar gaviria trujillo viaduct in the department of risaralda, colombia. results were successful in terms of solution and reliability of the network.
Dise o e implementación de una red de sensores para la adquisición de variables relacionadas con la vigilancia estructural de puentes
David Magín Flórez-Rubio,Camilo Otálora-Sánchez,Carlos Iván Páez-Rueda
Ingeniería y Universidad , 2009,
Abstract: This article details the design and implementation of a sensor network for structural surveillance of bridges. Such network was piloted at the César Gaviria Trujillo Viaduct in the department of Risaralda, Colombia. Results were successful in terms of solution and reliability of the network.
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