55 research outputs found

    Black holes in Einstein-Gau\ss -Bonnet-dilaton theory

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    Generalizations of the Schwarzschild and Kerr black holes are discussed in an astrophysically viable generalized theory of gravity, which includes higher curvature corrections in the form of the Gauss-Bonnet term, coupled to a dilaton. The angular momentum of these black holes can slightly exceed the Kerr bound. The location and the orbital frequency of particles in their innermost stable circular orbits can deviate significantly from the respective Kerr values. Study of the quasinormal modes of the static black holes gives strong evidence that they are mode stable against polar and axial perturbations. Future gravitational wave observations should improve the current bound on the Gauss-Bonnet coupling constant, based on observations of the low-mass x-ray binary A 0620-00.Comment: 8 pages, 7 figure

    Síndrome compartimental por extravasación de líquidos en paciente pediátrico, reporte de un caso y revisión de la literatura.: Compartment syndrome due to liquid extravasation in a pediatric patient. Case report and bibliographic review

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    Extravasation Compartment Syndrome (SCE) is an infrequent pathology, with an incidence of 0,01-6,5%, whom 1,8-11% are children. Communication in children is usually difficult, with high risk of development of SCE. A case about a 9 month old male patient with an over-infected viral pneumonia and a triggered SCE is presented. He received compartmental decompression of right forearm and right hand; however he presented mild sequelae. Treatment of extravasation injury is not always sufficient enough. Mild-to-moderate complications or SCE can be presented. Recognizing clinical manifestations and risk factors and the use of auxiliary studies is fundamental for a good diagnosis and as prevention in children. Faciotomies, gold standard for treatment, are not completely safe, and have an impact on morbidity. Early protocols against extravasation, early examination by surgeon and investigation about SCE in chil-dren are recommended.El S√≠ndrome Compartimental por Extravasaci√≥n (SCE) es una patolog√≠a poco frecuente, con una incidencia de 0,01-6,5%, 1.8-11% en ni√Īos. En ni√Īos peque√Īos la comunicaci√≥n es dif√≠cil y aumenta el riego de desarrollo de SCE. Se presenta un caso de un masculino de 9 meses de edad, con Neumon√≠a viral sobreinfectada que desencadena SCE; recibi√≥ descompresi√≥n compartimental del antebrazo y mano derecha; con desarrollo de secuelas leves. Aplicar tratamiento para lesi√≥n por extravasaci√≥n no siempre es suficiente; existen complicaciones leves-moderadas o SCE. Reconocer manifestaciones cl√≠nicas y factores de riesgo es fundamental para el diagn√≥stico, con estudios auxiliares como precauci√≥n en ni√Īos. La faciotom√≠a, tratamiento est√°ndar de oro; no es inocua e impacta en la morbilidad. Se recomiendan protocolos oportunos para extravasaci√≥n, valoraci√≥n temprana por cirujano, investigaciones en pediatr√≠a

    Dise√Īo de mezclas de hormigones autocompactantes con alto contenido de adiciones minerales y √°ridos de diferentes naturaleza para desempe√Īo en ambientes altamente agresivos

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    [EN] The advances in the use of self-compacting concrete (SCC) increases its consumption in construction materials. The SCC has ease of placement and refinement of the microstructure due to the increase of the volume of paste and fines thus improving the resistance to the penetration of aggressive agents. Therefore, its use is not limited to usual scenarios but focusing also to environments with severe operating conditions as is the case of energy transport infrastructures, often located in remote and extreme places. These conditions of application and location restrict the type of materials to be used in the design of concrete: type of aggregates, type of cement, use of supplementary cementitious materials (SCM), etc. The development of SCC also must imply an increase in the sustainability of the construction process by promoting the use of binders with mineral additions and limestone filler , in order to reduce the total cement content (due to the reduction of CO2 emissions associated to cement production) thus decreasing their environmental footprint. However, the incorporation of SCM implies the need to ensure compatibility with the chemical additives, superplasticizers, while maintaining the fresh state properties. Another relevant factor is the type and characteristics of aggregates that significantly affect the workability of concrete. The aggregates provide an improvement in performance in a hardened state, but in some cases they modify the consistency losing the self-compactibility of the concrete.The aim of this study is to evaluate the influence of the composition of the mixture components on the fresh and hardened properties of the SCC: 1) Interaction of the additives with cements with high mineral addition content (50%) of slag and fly ash; 2) the effect of the use of mixtures of aggregates with different origin, shape and composition that provide the special properties required concentrated solar power plants. Mixtures of aggregates, limestone, basalt and crushed Clinker have been considered along with additives that promote flowability, water reducers and density enhancement. Robust SCCs can be developed with high stability suitable for CSP application.[ES] El presente estudio se centra en el desarrollo de dosificaciones de hormigones autocompactantes (HAC) para ser empleados en la construcci√≥n de infraestructuras de almacenamiento de energ√≠a t√©rmica. En el estudio se han considerado tres aspectos b√°sicos: 1) selecci√≥n del cemento √≥ptimo (Binario con 50% escorias de alto horno y ternario con 20% de escorias de alto horno y 20% de cenizas volantes), 2) √°ridos de altas prestaciones t√©rmicas: calizo, bas√°ltico y Clinker de cemento, y 3) combinaci√≥n de aditivos para mejorar las caracter√≠sticas de trabajabilidad, fluidez y tiempo abierto. El dise√Īo de los hormigones se ha realizado en dos etapas: i) utilizando el m√©todo de morteros equivalentes, ii) HAC de altas prestaciones t√©rmicas. Se ha establecido el m√©todo de morteros equivalentes como una herramienta de apoyo en la fase preliminar del estudio, en el desarrollo del hormig√≥n. La compatibilidad de los diferentes tipos de aditivos con los cementos binarios y ternarios con alto contenido en adiciones minerales ha sido comprobada en los morteros equivalentes. Siempre la cantidad del aditivo superplastificante / Reductor de agua (SP/RA) es menor que el aditivo para mejorar la trabajabilidad (SP/T) y complementado con la Nano-s√≠lice (NS) usada adem√°s como modulador de viscosidad. El √°rido bas√°ltico mejora la fluidez, aumenta la densidad y resistencia, pero complica la trabajabilidad. El √°rido calizo aporta docilidad y baja la densidad. El √°rido de clinker mejora la trabajabilidad y aumenta la densidad. El filler calizo (FC) mejora la compacidad aunque en detrimento de las resistencias.Este estudio ha sido financiado parcialmente por el Proyecto LORCENIS, Project ID 685445 de la Comisi√≥n Europea dentro H2020. Los autores agradecen a la empresa Dyckerhoff por el suministro del cemento usado en este proyecto y a la empresa SIKA en el suministro de los aditivos.Puentes Mojica, J.; Calvo, J.; Alonso Alonso, M. (2018). Dise√Īo de mezclas de hormigones autocompactantes con alto contenido de adiciones minerales y √°ridos de diferentes naturaleza para desempe√Īo en ambientes altamente agresivos. En HAC 2018. V Congreso Iberoamericano de hormig√≥n autocompactable y hormigones especiales. Editorial Universitat Polit√®cnica de Val√®ncia. 177-186. https://doi.org/10.4995/HAC2018.2018.6324OCS17718

    Análisis de la educación ambiental en bogota en la zona 16 puente aranda

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    La contaminaci√≥n ambiental en nuestras √°reas urbanas y rurales constituyen una problem√°tica de inter√©s social el d√≠a de hoy, pues el responsable del deterioro de los habitas, entendido este como el entorno en el que la poblaci√≥n desarrolla la totalidad de sus actividades, la vivienda adecuada y la disponibilidad de sus servicios p√ļblicos en la vivienda constituyen componentes fundamentales para el ejercicio del derecho a un h√°bitat seguro y saludable. Adem√°s de las condiciones ambientales de la ciudad de Bogot√° y del pa√≠s, es el ser humano quien es responsable de sus acciones en los per√≠metros tanto urbanos como rurales. Por ello es importante que las entidades educativas, en todos sus diferentes grados intensifiquen y/o fortalezcan su curriculum o pensum del √°rea de Educaci√≥n Ambiental, o que el modelo pedag√≥gico actual sea revisado y se estructure con procesos de ense√Īanza decisivos, enmarcados hacia el medio ambiente, con el compromiso de todos individuos esta educaci√≥n debe estar orientada al desarrollo sostenible y buscando un mejoramiento en la calidad de vida de los ciudadanos. Lo anterior con el fin de transmitir una serie de valores y h√°bitos que conlleven a las futuras generaciones al respeto por nuestros recursos naturales y el ambiente. Dicha educaci√≥n ambiental debe ser replicada a nuestros familiares y conciudadanos, por todos y cada uno de los alumnos de las diferentes instituciones educativas, con una verdadera conciencia ambiental irradie el amor y respeto por nuestros recursos naturales y el ambiente. Lo anterior en corresponsabilidad como ciudadanos con las instituciones estatales, encargadas tambi√©n de la educaci√≥n ambiental y el control de medio ambiente en el Distrito Capital √°rea urbana y rural.Environmental pollution in our urban and rural areas becomes a problem of social interest today, since it is responsible for the habitat‚Äôs deterioration, understood as the environment in which the population develops all of its activities, adequate housing and the availability of its public services constitute fundamental components for the exercise of the right to a safe and healthy habitat. In addition to the environmental conditions of Bogot√° city and the country, it is the human being who is responsible for their actions in both urban and rural perimeters. For this reason, it is important that educational entities, in all their different degrees, intensify and/or strengthen their curriculum or pensum in the Environmental Education area, or the review of the current pedagogical model and restructuration with processes of decisive teaching, framed towards the environment, with the commitment of all individuals, this education must be oriented to the sustainable development and seeking an improvement in the quality of life of citizens. The foregoing in order to transmit a series of values and habits that lead future generations to respect our natural resources and the environment. This environmental education must be replicated to our relatives and fellow citizens, by each and every one of the students of the different educational institutions, with a true environmental conscience radiating love and respect for our natural resources and the environment. The foregoing in co-responsibility as citizens with state institutions, also in charge of environmental education and environmental control in the Capital District, urban and rural areas

    Utilization of Plant Refuses as Component of Heavy Metal Ion Sensors in Water Samples

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    Waste materials like fruit and vegetable refuses were utilized as component of sensors capable of detecting heavy metals like lead ions and mercury ions by electrochemical method. The ability of the fabricated sensors to detect the presence of heavy metals was analyzed using electrochemical methods like cyclic voltammetry and differential pulse anodic stripping voltammetry. Results showed that the fabricated electrode were able to detect the presence of mercury and lead ions in aqueous solutions

    The reaction mechanism of metallo-beta-lactamases is tuned by the conformation of an active site mobile loop

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    Carbapenems are "last resort" ő≤-lactam antibiotics used to treat serious and life-threatening health care-associated infections caused by multidrug-resistant Gram-negative bacteria. Unfortunately, the worldwide spread of genes coding for carbapenemases among these bacteria is threatening these life-saving drugs. Metallo-ő≤-lactamases (Mő≤Ls) are the largest family of carbapenemases. These are Zn(II)-dependent hydrolases that are active against almost all ő≤-lactam antibiotics. Their catalytic mechanism and the features driving substrate specificity have been matter of intense debate. The active sites of Mő≤Ls are flanked by two loops, one of which, loop L3, was shown to adopt different conformations upon substrate or inhibitor binding, and thus are expected to play a role in substrate recognition. However, the sequence heterogeneity observed in this loop in different Mő≤Ls has limited the generalizations about its role. Here, we report the engineering of different loops within the scaffold of the clinically relevant carbapenemase NDM-1. We found that the loop sequence dictates its conformation in the unbound form of the enzyme, eliciting different degrees of active-site exposure. However, these structural changes have a minor impact on the substrate profile. Instead, we report that the loop conformation determines the protonation rate of key reaction intermediates accumulated during the hydrolysis of different ő≤-lactams in all Mő≤Ls. This study demonstrates the existence of a direct link between the conformation of this loop and the mechanistic features of the enzyme, bringing to light an unexplored function of active-site loops on Mő≤Ls.Fil: Palacios, Antonela Rocio. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Cient√≠fico Tecnol√≥gico Conicet - Rosario. Instituto de Biolog√≠a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioqu√≠micas y Farmac√©uticas. Instituto de Biolog√≠a Molecular y Celular de Rosario; ArgentinaFil: Mojica, Mar√≠a F.. Case Western Reserve University; Estados UnidosFil: Giannini, Estefan√≠a. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Cient√≠fico Tecnol√≥gico Conicet - Rosario. Instituto de Biolog√≠a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioqu√≠micas y Farmac√©uticas. Instituto de Biolog√≠a Molecular y Celular de Rosario; ArgentinaFil: Taracila, Magdalena A.. Case Western Reserve University; Estados Unidos. Louis Stokes Veterans Affairs Medical Center; Estados UnidosFil: Bethel, Christopher R.. Louis Stokes Veterans Affairs Medical Center; Estados UnidosFil: Alzari, Pedro M.. Institut Pasteur de Paris; FranciaFil: Otero, Lisandro Horacio. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Oficina de Coordinaci√≥n Administrativa Parque Centenario. Instituto de Investigaciones Bioqu√≠micas de Buenos Aires. Fundaci√≥n Instituto Leloir. Instituto de Investigaciones Bioqu√≠micas de Buenos Aires; ArgentinaFil: Klinke, Sebastian. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Oficina de Coordinaci√≥n Administrativa Parque Centenario. Instituto de Investigaciones Bioqu√≠micas de Buenos Aires. Fundaci√≥n Instituto Leloir. Instituto de Investigaciones Bioqu√≠micas de Buenos Aires; ArgentinaFil: Llarrull, Leticia Irene. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Cient√≠fico Tecnol√≥gico Conicet - Rosario. Instituto de Biolog√≠a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioqu√≠micas y Farmac√©uticas. Instituto de Biolog√≠a Molecular y Celular de Rosario; ArgentinaFil: Bonomo, Robert A.. Case Western Reserve University; Estados UnidosFil: Vila, Alejandro Jose. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas. Centro Cient√≠fico Tecnol√≥gico Conicet - Rosario. Instituto de Biolog√≠a Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioqu√≠micas y Farmac√©uticas. Instituto de Biolog√≠a Molecular y Celular de Rosario; Argentin

    In Vitro Susceptibility to Ceftazidime/Avibactam and Comparators in Clinical Isolates of Enterobacterales from Five Latin American Countries

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    Background: High rates of resistance to third-generation cephalosporins and carbapenems in Enterobacterales have been reported in Latin America. Ceftazidime/avibactam (CZA) is the combination of a third-generation cephalosporin and a non-ő≤-lactam ő≤-lactamase inhibitor, which hasshown activity against isolates producing class A, C and D ő≤-lactamases. Herein, we evaluated the activity of CZA and comparators against clinical isolates of Enterobacterales in Latin America. Methods: The activity of CZA and comparators was evaluated against clinical isolates of Enterobacterales from Argentina, Brazil, Chile, Colombia and Mexico that were collected between January 2016 andOctober 2017. One specific phenotypic subset was evaluated. A carbapenem non-susceptible (CNS) phenotype was defined as any isolate displaying a minimum inhibitory concentration (MIC) ‚Č•1 mg/L for ertapenem. Results: CZA was active against 95.8% of all isolates and 77.5% of CNS isolates. Fosfomycin (FOS) and tigecycline (TGC) were the second most active antibiotics with 93.4% ofEnterobacterales being susceptible. Conclusions: The results of this study underline the potential therapeutic role of CZA in Latin AmericaFil: Appel, Tobias Manuel. Universidad El Bosque; ColombiaFil: Mojica, Maria Fernanda. Universidad El Bosque; ColombiaFil: De La Cadena, Elsa. Universidad El Bosque; ColombiaFil: Pallares, Cristian. Universidad El Bosque; ColombiaFil: Radice, Marcela Alejandra. Universidad de Buenos Aires. Facultad de Farmacia y Bioqu√≠mica. Departamento de Microbiolog√≠a, Inmunolog√≠a y Biotecnolog√≠a. C√°tedra de Microbiolog√≠a; Argentina. Consejo Nacional de Investigaciones Cient√≠ficas y T√©cnicas; ArgentinaFil: Casta√Īeda M√©ndez, Paulo. Hospital M√©dica Sur; M√©xicoFil: Jaime-Villal√≥n, Diego. Hospital San Angel; M√©xicoFil: Gales, Ana. Universidade de Sao Paulo; BrasilFil: Munita, Jose. No especif√≠ca;Fil: Villegas, Maria. Universidad El Bosque; Colombi
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