829 research outputs found

    Correlations across horizons in quantum cosmology

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    Different spacetime regions separated by horizons are not related to each other. We know that this statement holds for classical spacetimes. In this paper we carry out a canonical quantization of a Kantowski-Sachs minisuperspace model whose classical solutions exhibit both an event horizon and a cosmological horizon in order to check whether the above statement also holds from the quantum gravitational point of view. Our analysis shows that in fact this is not the case: Quantum gravitational states with support in spacetime configurations that exclusively describe either the region between horizons or outside them are not consistent in the sense that there exist unitary operators describing a natural notion of evolution that connect them. In other words, unitarity is only preserved in this quantization when dealing with the whole spacetime and not in each region separately.Comment: 10 pages, 5 figure

    Sugerencias sobre el margen SO de Gondwana: Bioestratigrafía de conodontes y graptolitos del Ordovícico en bloques alóctonos de la mélange Rinconada, precordillera Argentina

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    The Rinconada Formation is a mélange that crops out in the eastern margin of the Argentine Precordillera, an exotic terrane accreted to Gondwana in Ordovician times. Its gravity-driven deposits have been studied by means of conodont and graptolite biostratigraphy, and complemented with stratigraphic analyses. 46 rock samples (85 kg total weight) were obtained from blocks of limestones and of carbonate-cemented quartz-arenites, and from limestone clasts included in conglomerate blocks and debrites. 16 of these samples were productive after standard laboratory acid procedures, yielding 561 conodont elements. The specimens occur in variable number per sample and are frequently fragmented, but they reveal the occurrence of phantom stratigraphic units in the Darriwilian of the Precordillera. Lithological and fossil evidence from the Rinconada Formation provide new constraints on the biostratigraphy, palaebiogeography and tectonostratigraphic history of the southwestern margin of Gondwana during the Ordovician to Lower Devonian times.La Formación Rinconada es una mélange que aflora en el margen oriental de la precordillera Argentina, parte de un terreno exótico acrecionado a Gondwana durante el Ordovícico. Los depósitos gravitacionales de la mélange se han estudiado mediante bioestratigrafía de conodontes y graptolitos, complementados con análisis estratigráficos. Con este fin se obtuvieron 46 muestras de roca (85 kg peso total) de bloques de caliza, de bloques de cuarzoarenitas con cemento carbonático, y de clastos de calizas incorporados en bloques de conglomerados y debritas. Luego del tratamiento estándar de laboratorio, 16 muestras fueron productivas, brindando 561 elementos de conodontes. Los especímenes se encuentran en número variable por muestra y frecuentemente fragmentados; aun así, permiten revelar la existencia de unidades estratigráficas fantasma en el Darriwiliano de la precordillera. La evidencia paleontológica y litológica de la Formación Rinconada brinda nuevos ajustes para el Ordovícico a Devónico Temprano en relación con la bioestratigrafía, paleobiogeografía e historia tectonoestratigráfica del margen sudoccidental de Gondwana.Fil: Voldman, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Alonso, Juan Luis. Universidad de Oviedo; EspañaFil: Fernández, Luis P.. Universidad de Oviedo; EspañaFil: Ortega, Gladys del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas, CIGEA and Museo de Paleontología, Universidad Nacional de Córdoba; ArgentinaFil: Albanesi, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Banchig, Aldo Lui. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; ArgentinaFil: Cardó, Raúl. Servicio Geológico y Minero Argentino, San Juan, Argentina; Argentin

    Characterization of a Functional NTPDase in the Endoplasmic Reticulum of Rat Submandibular Salivary Gland

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    Nucleotidase activity and Ca-uptake were characterized in endoplasmic reticulum (ER) enriched rat submandibular gland (SMG) microsomal preparations. (i) Ca-uptake had characteristics of an ER Ca-ATPase. (ii) Nucleotidase activity was equally stimulated by calcium, magnesium and manganese, but with different Km values. (iii) Specific inhibitors of P-type Ca-ATPases were ineffective on nucleotidase activity, demonstrating that this activity was not related to calcium uptake and did not correspond to classical Ca2+ pumps. (iv) ATP and UTP were more efficient substrates, whereas ADP and UDP were hydrolyzed at significantly slower rate. (v) Nucleotidase activity was sensitive to mild detergent solubilization and insensitive to ionophore addition. (vi) Nucleotidase activity was strongly inhibited by suramin, a nucleoside triphosphate diphosphohydrolase (NTPDase) inhibitor. (vii) Nucleotidase activity exponentially diminished as function of time. All these observations are consistent with a NTPDase identity. The presence of a NTPDase was demonstrated by immunohistochemistry in rat SMG. Immunoreactivity was stronger in ductal cells than in mucous and serous acini. Although this enzyme was observed in the plasma membrane, colocalization with the ER marker calnexin revealed a specific subcellular localization in this organelle of all three types of cell. The putative function of this NTPDase activity in salivary glands is discussed.Fil: Ostuni, M. A.. Inserm; Francia. Université Paris; Francia. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Egido, P.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Peranzi, G.. Inserm; Francia. Université Paris; FranciaFil: Alonso, Guillermo Luis. Universidad de Buenos Aires. Facultad de Odontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lacapere, J. J.. Inserm; Francia. Université Paris; FranciaFil: Gonzalez, D. A.. Inserm; Francia. Université Paris; Franci

    Nanogel Formation from Dilute Solutions of Clickable Elastin-like Recombinamers and its Dependence on Temperature: Two Fractal Gelation Modes

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    Producción CientíficaDiluted, complementary, click-reactive elastin-like recombinamer (ELR) solutions have been prepared and mixed at two different temperatures, one below and one above the characteristic transition temperature (Tt) of these chemically modified ELRs. FTIR measurements, size, aspect ratio, zeta potential, and microrheological measurements have been carried out on the nanostructures formed under these dilute conditions as a way to better understand the relationship between the final macroscopic properties of ELR-based hydrogels and the molecular conditions governing the initial stages of the chemical cross- linking process that occurs, especially its dependence on the preparation temperature relative to Tt. As a result, two different fractal modes of gel formation have been found at the two temperatures studied (above and below Tt). Thus, when the reaction mixture is prepared below Tt, essentially one-dimensional linear nanogels with a high aspect ratio are obtained. In contrast, 3D nanogels are formed above Tt, with spherical shapes predominating. These different structures seem to reflect the two molecular organizations of the single components of the mixture under these conditions, namely extended chains below Tt and a spherical arrangement above Tt. In addition to the interest in these nanogels as models for understanding the formation of microscopic structures and differential macroscopic properties under more conventional hydrogel-formation conditions, these nanogels are of interest because of their thermoresponsiveness and biocompatibility, which provide them with potential uses for drug delivery and other biomedical applications in living systems.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA244U13

    Quantum correlations across cosmological horizons

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    Presentación en Power Point: 18 diapositivasPeer reviewe

    Biweekly cetuximab in combination with FOLFOX-4 in the first-line treatment of wild-type KRASmetastatic colorectal cancer: final results of a phase II, open-label, clinical trial (OPTIMIX-ACROSS Study)

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    Background: This phase II study aims to evaluate the efficacy and safety of biweekly cetuximab in combination with oxaliplatin, leucovorin, and fluorouracil (FOLFOX-4) as first-line treatment of metastatic wild-type KRAS colorectal cancer. Methods: Previously untreated patients with wild-type KRAS tumours received biweekly cetuximab (500 mg/m2 on day 1) plus FOLFOX-4 (oxaliplatin 85 mg/m2 on day 1, leucovorin 200 mg/m2 on days 1 and 2, and fluorouracil as a 400 mg/m2 bolus followed by a 22-hour 600 mg/m2 infusion on day 1 and 2). Treatment was continued until disease progression, onset of unacceptable toxicities, metastases surgery, or discontinuation request. The primary endpoint was ORR. Results: The intention-to-treat population included 99 patients with a median age of 64.1 years (range, 34-82). The ORR was 60.6% (95% CI, 50.3% to 70.3%). The median follow-up was 17.8 months; the median OS and PFS were 20.8 and 10.1 months, respectively. Metastases from colorectal cancer were surgically resected in 26 (26.3%) patients, with complete resection achieved in 18 (69.2%) patients. Median PFS and OS in patients undergoing metastatic resection were 12.6 and 29.5 months, respectively. The most common grade 3-4 toxicities were neutropenia (32.3%), acne-like rash (15.2%) and diarrhoea (11.1%). Conclusions: The efficacy of the biweekly combination of cetuximab with FOLFOX-4 in patients with wild-type KRAS tumours supports the administration of cetuximab in a dosing regimen more convenient for patients and healthcare providers. The activity of the biweekly administration is similar to what has been reported for the weekly regimen. Reported toxicity was also consistent with the known toxicity profile of weekly cetuximab. Trial registration: EudraCT Number 20080069091

    Diseño de plan de acción en materia de seguridad e higiene industrial del trabajo para la prevención de factores de riesgos en áreas seleccionadas de la empresa Tritón Minera S.A.

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    Presenta un plan de acción en materia de seguridad e higiene industrial del trabajo que permite reducir los riesgos presente en algunas de las áreas de la empresa TRITON MINERA S.A entre el periodo de mayo a septiembre de 2011

    An Economic Analysis of the Environmental Impact of PM2.5 Exposure on Health Status in Three Northwestern Mexican Cities

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    Introduction: This study provides an economic assessment of the health effects due to exposure to particulate matter PM2.5 in three medium-size cities of northwestern Mexico: Los Mochis, Culiacan and Mazatlán. People in these cities are exposed to high pollutant concentrations that exceed limits suggested in domestic and international guidelines. PM2.5 is an air contaminant negatively associated with people’s health when is highly concentrated in the atmosphere; its diameter is below 2.5 µm and causes the air to appear hazy when levels are elevated. To account for the economic impact of air pollution, a Health Impact Assessment (HIA) was used by the means of the European Aphekom Project. We figured the cost-savings of complying with current environmental standards and computed gains in life expectancy, total avoidable premature mortality, preventable cardiovascular disease, and the economic costs of air pollution related to PM2.5. A formal analysis of air pollution epidemiology is not pursued in this paper. Results: The cost of reducing PM2.5 pollution associated with negative health outcomes was based on two different scenarios: Official Mexican Standard (NOM, Spanish acronym) and World Health Organization (WHO) environmental standards. The mean PM2.5 concentrations in 2017 were 22.8, 22.4 and 14.1 µg/m3 for Los Mochis, Mazatlán and Culiacan, respectively. Conclusions: The mean avoidable mortality for all causes associated to PM2.5 exposure in these cities was 638 for the NOM scenario (i.e., with a reduction to 12 µg/m3) compared to 739 for the WHO scenario (reduction to 10 µg/m3). Complying with the WHO guideline of 10 µg/m3 in annual PM2.5 mean would add up to 15 months of life expectancy at age 30, depending on the city. The mean economic cost per year of the PM2.5 effects on human life in these three cities was USD 600 million (NOM scenario) and USD 695 million (WHO scenario). Thus, effective public health and industrial policy interventions to improve air quality are socially advantageous and cost-saving to promote better health.S

    Low survival rate and muscle fiber-dependent aging effects in the McArdle disease mouse model

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    Survival rate; McArdle disease; Mouse modelTaxa de supervivència; Malaltia de McArdle; Model de ratolíTasa de supervivencia; Enfermedad de McArdle; Modelo de ratónMcArdle disease is an autosomal recessive disorder caused by the absence of the muscle glycogen phosphorylase, which leads to impairment of glycogen breakdown. The McArdle mouse, a model heavily affected by glycogen accumulation and exercise intolerance, was used to characterize disease progression at three different ages. The molecular and histopathological consequences of the disease were analyzed in five different hind-limb muscles (soleus, extensor digitorum longus, tibialis anterior, gastrocnemius and quadriceps) of young (8-week-old), adult (35-week-old) and old (70-week-old) mice. We found that McArdle mice have a high perinatal and post-weaning mortality. We also observed a progressive muscle degeneration, fibrosis and inflammation process that was not associated with an increase in muscle glycogen content during aging. Additionally, this progressive degeneration varied among muscle and fiber types. Finally, the lack of glycogen content increase was associated with the inactivation of glycogen synthase and not with compensatory expression of the Pygl and/or Pygb genes in mature muscle.ISCIII CD14/00032/Ministry of Economy and Competitiveness | Instituto de Salud Carlos III (Institute of Health Carlos III
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