Geologic Evolution and its relationship with the Epithermal Mineralization at the El Dorado-Monserrat Area, Deseado Massif, Santa Cruz, Argentina

En este trabajo se han estudiado las características litológicas y estructurales del área comprendida entre las Estancias El Dorado y Monserrat, Macizo del Deseado, Argentina y sus relaciones con la mineralización epitermal. La mineralización se hospeda en rocas volcánicas del Jurásico medio, correspondiente a la Formación Bajo Pobre, y se encuentra ligada genéticamente a la Formación Chon Aike (Jurásico medio-superior), la que se ha dividido en 4 subunidades conformadas por ignimbritas, megabrechas, depósitos de caída piroclástica y lavas acidas. La ubicación y distribución de estas litologías, junto con el análisis estructural han permitido explicar el desarrollo de los centros volcánicos (tipo caldera), su posterior fracturación y su relación con la mineralización epitermal.This paper deals with the litological and structural characteristics of the El Dorado-Monserrat area, Deseado Massif, Argentina, and its relationship with the epithermal mineralization. The mineralization is hosted by mid-Jurassic volcanic rocks of the Bajo Pobre Formation, and its origin is related to the Chon Aike Formation (mid-upper Jurassic), where four sub-units have been identified. These are composed by ignimbrites, megabreccias, piroclastic fall deposits, and volcanic flows. The location and distribution of the mentioned units together with the structural features of the region have allowed to explain the volcanic center (caldera type) development, its later regional fracturing, and how these episodes are related to the epithermal mineralization.Instituto de Recursos Minerale

Caracterización electroquímica de cuatro biomateriales metálicos de uso odontológico

ABSTRACT: The use of alloys with a minimum of 50% gold-content to minimize the potential of corrosion or galvanism in the implant- restoration interface has been suggested in the literature. However, long – term implications of placing two different kinds of metal at this level is still unknown. The purpose of this study was to perform the electrochemical characterization of four metallic biomaterials used in dentistry, to determine the possibility of corrosion among them when placed in contact during restorative procedures on implant fixtures. A prospective, descriptive, comparative, In - Vitro study was made for this purpose. Four types of metallic biomaterials were compared: commercially pure titanium using as a sample a Super CAT® implant (Lifecore Biomedical Inc., Chaska, MN); highly - noble alloy with a cast made from an UCLA abutment (Lifecore Biomedical Inc., Chaska, MN) with an IPS d.sing® 91 alloy (Williams, Ivoclar Vivadent AG, Liechtenstein); metal-base alloy with a cast made from an UCLA abutment with an IPS d.sing® 15 alloy; titanium alloy (Ti6Al4V) using a Lifecore COC® prosthetic abutment. The electrochemical characterization was made using a Bas Zahner potentiostat, with a three – electrode setup, obtaining three polarization curves for each group in its passive and non passive forms. The results showed that the titanium alloy had the best electrochemical behavior in both passive and non-passive state, which led to the smallest passive currents. The lowest corrosion potential was obtained for the metal-base alloy, because it had the highest passive currents.RESUMEN: En la literatura médica se ha sugerido el uso de aleaciones con un mínimo de 50% de contenido de oro para minimizar la corrosión en la unión implante-restauración. Sin embargo, las implicaciones clínicas a largo plazo de la colocación de dos metales diferentes en restauraciones sobre implantes es aún desconocido. El objetivo de este estudio es realizar la caracterización electroquímica de cuatro biomateriales metálicos de uso odontológico para determinar la posibilidad de corrosión entre ellos cuando se ponen en contacto durante los procedimientos restauradores sobre implantes. Se realizó un estudio in vitro de tipo descriptivo, prospectivo y comparativo. Se trabajó con cuatro tipos de biomateriales metálicos: titanio comercialmente puro, tomando como muestra un implante SuperCAT® de la casa Lifecore (Lifecore Biomedical Inc., Chaska, MN.); metal altamente noble, con un colado que se realizó a partir de un pilar plástico tipo UCLA® (Lifecore Biomedical Inc., Chaska, MN), con aleación IPS d.sign 91® (Williams, Ivoclar Vivadent AG, Liechtenstein); aleación de metal base con un colado que se realizó a partir de un pilar plástico tipo UCLA® con aleación IPS d.sign 15®, y aleación de titanio (Ti6Al 4V), usando un aditamento protésico tipo COC® de la casa comercial Lifecore. Se hizo la caracterización electroquímica de las cuatro aleaciones metálicas mediante un potenciostato Bas Zähner, con una celda de tres electrodos, usando como electrodo de referencia el electrodo de Ag/AgCl, obteniendo tres curvas de polarización para cada grupo en su forma pasivada y sin pasivar. La lectura de las curvas potenciodinámicas realizadas en este estudio, con cuatro biomateriales metálicos, y tomando como criterio el potencial de corrosión, concluye un excelente comportamiento para la aleación de titanio y de metales altamente nobles. La mejor combinación, teniendo en cuenta los criterios de potencial de corrosión y corriente a potenciales anódicos, se da con el titanio comercialmente puro y la aleación de titanio

Devenir maestro : narrativas desde el ser maestro en el territorio

RESUMEN: ¿Qué puede resultar de una práctica pedagógica en un contexto rural? ¿Qué cree usted que podría leer en el entramado de cartas compartidas por cuatro estudiantes? ¿Qué descubrirá en las historias de maestros que comprenden el territorio más allá de lo físico y lo vivencian desde sus construcciones simbólicas? ¿Qué reflexión se condensará en el acto de repensar conceptos como Maestro, Educación, Narrativa, Epístola y Territorio? Encontrarse aquí, dispuesto a leer o escribir, según sea su caso, es prepararse para una experiencia que lo conducirá, a través de lo biográfico-narrativo, para comprender la apuesta de cuatro estudiantes, de cuatro maestros en formación que le apuestan a una resignificación de la propia experiencia y a una reconfiguración de su ser maestro. Bienvenidos a esta experiencia que para nosotros (y esperamos, para ustedes), significa un proceso de constante reflexión, reconceptualización, repensamiento y construcción narrativa de nuestra formación académica y humana.ABSTRACT: What can result from a pedagogical practice in a rural context? What do you think you could read in a epistolary framework of four students? What will you discover in teacher’s stories who understand the territory beyond the physical and lives it from its symbolic constructions? What reflection will be condensed in the act of rethinking concepts such as Teacher, Education, Narrative, Epistle and Territory? To be here, willing to read and/or write, as the case may be, is to prepare for an experience that will lead you, through the biographical-narrative, to understand the bet of four students, of four teachers in training who bet on a resignification of their experience and a reconfiguration of their being master. Welcome to this experience that meaning for us (we hope you too), a constant reflection, reconceptualization, rethinking and narrative construction process of our academic and human formation

EL CONCEPTO DE AMBIENTE: ¿UN LENGUAJE COMUN ENTRE MUSEOS DE CIENCIAS E INSTITUCIONES EDUCATIVAS

En el sector educativo, la educación ambiental se ha venido incluyendo como una de las herramientas importantes dentro de las nuevas políticas internacionales. Partiendo de este hecho, se puede evidenciar en este artículo cómo los espacios de educación no formal como los Museos de Ciencias Naturales, pueden incidir en la construcción de un concepto de “ambiente” que trascienda de una dimensión físico-natural a una dimensión que haga participe al hombre y su cultura como variable importante en el cuidado y preservación de la naturaleza.Desde esta perspectiva, esta investigación pone de manifiesto las transformaciones en el concepto de ambiente que construyen los estudiantes del grado séptimo de la Institución Educativa Concejo de Bello, en la interacción con los discursos utilizados por los guías-mediadores de museos

Reporte Estabilidad Financiera - Primer Semestre de 2020

In the face of the multiple shocks currently experienced by the domestic economy (resulting from the drop in oil prices and the appearance of a global pandemic), the Colombian financial system is in a position of sound solvency and adequate liquidity. At the same time, credit quality has been recovering and the exposure of credit institutions to firms with currency mismatches has declined relative to previous episodes of sudden drops in oil prices. These trends are reflected in the recent fading of red and blue tonalities in the performance and credit risk segments of the risk heatmaps in Graphs A and B.1 Naturally, the sudden, unanticipated change in macroeconomic conditions has caused the appearance of vulnerabilities for short-term financial stability. These vulnerabilities require close and continuous monitoring on the part of economic authorities. The main vulnerability is the response of credit and credit risk to a potential, temporarily extreme macroeconomic situation in the context of: (i) recently increased exposure of some banks to household sector, and (ii) reductions in net interest income that have led to a decline in the profitability of the banking business in the recent past. Furthermore, as a consequence of greater uncertainty and risk aversion, occasional problems may arise in the distribution of liquidity between agents and financial markets. With regards to local markets, spikes have been registered in the volatility of public and private fixed income securities in recent weeks that are consistent with the behavior of the international markets and have had a significant impact on the liquidity of those instruments (red portions in the most recent past of some market risk items on the map in Graph A). In order to adopt a forward-looking approach to those vulnerabilities, this Report presents a stress test that evaluates the resilience of credit institutions in the event of a hypothetical scenario thatseeks to simulate an extreme version of current macroeconomic conditions. The scenario assumes a hypothetical negative growth that is temporarily strong but recovers going into the middle of the coming year and has extreme effects on credit quality. The results suggest that credit institutions have the ability to withstand a significant deterioration in economic conditions in the short term. Even though there could be a strong impact on credit, liquidity, and profitability under the scenario being considered, aggregate capital ratios would probably remain at above their regulatory limits over the horizon of a year. In this context, the recent measures taken by both Banco de la República and the Office of the Financial Superintendent of Colombia that are intended to help preserve the financial stability of the Colombian economy become highly relevant. In compliance with its constitutional objectives and in coordination with the financial system’s security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth functioning of the payment system. Juan José Echavarría Governo

Financial Stability Report - Second Semester of 2020

The Colombian financial system has not suffered major structural disruptions during these months of deep economic contraction and has continued to carry out its basic functions as usual, thus facilitating the economy's response to extreme conditions. This is the result of the soundness of financial institutions at the beginning of the crisis, which was reflected in high liquidity and capital adequacy indicators as well as in the timely response of various authorities. Banco de la República lowered its policy interest rates 250 points to 1.75%, the lowest level since the creation of the new independent bank in 1991, and provided ample temporary and permanent liquidity in both pesos and foreign currency. The Office of the Financial Superintendent of Colombia, in turn, adopted prudential measures to facilitate changes in the conditions for loans in effect and temporary rules for rating and loan-loss provisions. Finally, the national government expanded the transfers as well as the guaranteed credit programs for the economy. The supply of real credit (i.e. discounting inflation) in the economy is 4% higher today than it was 12 months ago with especially marked growth in the housing (5.6%) and commercial (4.7%) loan portfolios (2.3% in consumer and -0.1% in microloans), but there have been significant changes over time. During the first few months of the quarantine, firms increased their demands for liquidity sharply while consumers reduced theirs. Since then, the growth of credit to firms has tended to slow down, while consumer and housing credit has grown. The financial system has responded satisfactorily to the changes in the respective demands of each group or sector and loans may grow at high rates in 2021 if GDP grows at rates close to 4.6% as the technical staff at the Bank expects; but the forecasts are highly uncertain. After the strict quarantine implemented by authorities in Colombia, the turmoil seen in March and early April, which was evident in the sudden reddening of macroeconomic variables on the risk heatmap in Graph A,[1] and the drop in crude oil and coal prices (note the high volatility registered in market risk for the region on Graph A) the local financial markets stabilized relatively quickly. Banco de la República’s credible and sustained policy response played a decisive role in this stabilization in terms of liquidity provision through a sharp expansion of repo operations (and changes in amounts, terms, counterparties, and eligible instruments), the purchases of public and private debt, and the reduction in bank reserve requirements. In this respect, there is now abundant aggregate liquidity and significant improvements in the liquidity position of investment funds. In this context, the main vulnerability factor for financial stability in the short term is still the high degree of uncertainty surrounding loan quality. First, the future trajectory of the number of people infected and deceased by the virus and the possible need for additional health measures is uncertain. For that reason, there is also uncertainty about the path for economic recovery in the short and medium term. Second, the degree to which the current shock will be reflected in loan quality once the risk materializes in banks’ financial statements is uncertain. For the time being, the credit risk heatmap (Graph B) indicates that non-performing and risky loans have not shown major deterioration, but past experience indicates that periods of sharp economic slowdown eventually tend to coincide with rises in non-performing loans: the calculations included in this report suggest that the impact of the recession on credit quality could be significant in the short term. This is particularly worrying since the profitability of credit establishments has been declining in recent months, and this could affect their ability to provide credit to the real sector of the economy. In order to adopt a forward-looking approach to this vulnerability, this Report presents several stress tests that evaluate the resilience of the liquidity and capital adequacy of credit institutions and investment funds in the event of a hypothetical scenario that seeks to simulate an extreme version of current macroeconomic conditions. The results suggest that even though there could be strong impacts on the credit institutions’ volume of credit and profitability under such scenarios, aggregate indicators of total and core capital adequacy will probably remain at levels that are above the regulatory limits over the horizon of a year. At the same time, the exercises highlight the high capacity of the system's liquidity to face adverse scenarios. In compliance with its constitutional objectives and in coordination with the financial system's security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth operation of the payment systems. Juan José Echavarría Governo

Didactic strategy for the development of skills and abilities that facilitate the understanding of the mathematical modeling of ideal gases

ilustraciones, diagramas, tablasEn este trabajo se presenta la construcción e implementación de una propuesta didáctica de estrategias de enseñanza para la modelización matemática de la ley de los gases, para una población objetivo estudiantil de educación básica. El referente principal para esta propuesta se halla en la teoría constructivista del aprendizaje significativo crítico de Moreira. Desde esta perspectiva, la matemática es determinante a la hora de la enseñanza y el aprendizaje de la química. Ante las dificultades que se presentan en el aula con relación a la enseñanza surge la necesidad de dar respuesta a preguntas mediante un enfoque de investigación-acción. Como consecuencia, la transformación de su práctica pedagógica a través de la reflexión crítica le permite sistematizar su práctica, con el objetivo de reflexionarla y transformarla en acción. (Texto tomado de la fuente)This paper presents the construction and implementation of a didactic proposal of teaching strategies for the mathematical modeling of the gas law, for a target population of elementary school students. The main reference for this proposal is Moreira's constructivist theory of critical meaningful learning. From this perspective, mathematics is a determining factor in the teaching and learning of chemistry. Faced with the difficulties that arise in the classroom in relation to teaching, the need arises to answer questions through an action-research approach. Therefore, the transformation of their pedagogical practice through critical reflection allows to systematize their practice, with the aim of reflecting on it and transforming it into action.MaestríaMagíster en Enseñanza de las Ciencias Exactas y Naturalesinvestigación-acción pedagógica

Estudio económico a corto y largo plazo de una edificación aislada sísmicamente en su base mediante aisladores elastoméricos

102 páginasDiversos estudios realizados dan cuenta de las bondades que representa el uso de dispositivos de control de respuesta sísmica en estructuras. Esta investigación discute acerca de cómo se mejora el desempeño estructural con estos dispositivos, lo cual se traduce en la viabilidad económica de proyectos con aislamiento sísmico por sus beneficios en el corto y largo plazo. El objetivo de la investigación es realizar una estimación de los costos que implica la implementación de aisladores basales como dispositivos de control de respuesta sísmica, adicionalmente se destacan los beneficios en cuanto al desempeño de la estructura y la seguridad de los usuarios y los constructores. Se analizan cuatro estructuras hospitalarias tipo pórtico en concreto reforzado con capacidad de disipación de energía moderada (DMO) ubicadas en la ciudad de Medellín, dos de ellas de seis pisos con igual configuración geométrica salvo que una se concibe empotrada y la otra aislada en la base, las otras dos estructuras son de diez pisos con iguales condiciones estructurales. Se realiza el diseño de las estructuras empotradas bajo el Reglamento Colombiano de Construcción Sismo Resistente (NSR-10) y de las estructuras aisladas mediante la normativa Estadounidense FEMA 451 junto con la NSR-10. Posterior al diseño se realiza un análisis dinámico no lineal utilizando una serie de registros de aceleraciones de sismos importantes que han sucedido en la historia. Los resultados del análisis permiten determinar el índice de daño de los elementos estructurales mediante el método de Park & Ang, que finalmente conducen a cuantificar costos futuros por reparaciones debido a disminución en daño de elementos estructurales y lucro cesante de operación. Se concluye de la investigación que la implementación de aisladores elastómeros de núcleo de plomo favorecen la economía en el corto plazo por disminución en materiales (acero y concreto) y en el largo plazo porque se garantiza la vida útil de la estructura, no se incurre en lucro cesante por cese de actividades, se disminuyen las aceleraciones de piso y el daño en los elementos estructurales es considerablemente menor que en la estructura empotrada lo cual implica que disminuye el costo de reparaciones en la estructura. Esta investigación pretende incentivar el uso de dispositivos de control de respuesta sísmica dando cuenta de los beneficios que trae consigo esta tecnología, además del beneficio económico que se genera también es de suma importancia la seguridad e integridad de las personas que habitan, laboran o concurren las edificaciones aisladas y evitar calamidades debido a sismos.Several studies have realized the benefits involved in the use of devices for seismic response control in structures. This research discusses how the structural performance with these devices is improved, which results in the economic viability of projects with seismic isolation for its benefits in the short and long term. The aim of the research is to estimate the costs of implementing basal isolators as devices for seismic response control, further highlights the benefits in performance of the structure and safety of users and builders. Four gantry hospital structures in reinforced concrete are analyzed. They are located in the city of Medellín and have moderate energy dissipation capacity (DMO). Two of the structures have six floors with equal geometry, one is conceived with base isolation and the other one is a conventional structure. Two other ten floor structures with the same structural conditions are also analyzed. The design of the structures is made following the Colombian Earthquake Resistant Building Regulations (NSR-10) and the isolated structures following the American FEMA 451 standards as long as the NSR-10. Subsequent to the design, a nonlinear dynamic analysis is performed using a serie of accelerations records from important earthquakes that have happened in history. The results of the analysis allow determining the rate of damage to the structural elements by the Park & Ang method, finally leading to quantify future repair costs due to decreased damage of structural elements, and loss due to operating. It is concluded from the research that the implementation of lead core elastomeric isolators favor the economy in the short-term due to a decrease in materials (steel and concrete) and in the long term because the life of the structure is guaranteed, not incurred lost profits by stoppage, floor accelerations and damage to the structural elements decrease is considerably less than in-ground structure which implies that lowers the cost of repairs to the structure. This research aims to encourage the use of seismic response control devices realizing the benefits that this technology brings to the structure, in addition to the economic benefit generated, also very important the security and integrity of the people living, working or attend the isolated buildings and avoid disasters due to earthquakes.Modalidad: Trabajo de grado de pregrado exploratori

Costo de hospitalización domiciliaria como alternativa de la hospitalización institucional.periodo enero-diciembre de 2007

Objective: To evaluate the cost of hospital at home compared to hospital institution, taking into account the epidemiological profile and the days stay. Methods: A retrospective. longitudinal. conducted with patients of an insurance company with products like health insurance and prepaid~medicine. which made use of hospital and institutional home for the period January to December of 2007. Results: We found that the cost of home hospitalization is 18% of the total institutional cost of hospitalization. The difference was evaluated by epidemiological profile and number of days stay. Conclusions: The home care is an option to reduce the cost of care and allows the recovery of the patient in his environment.Objetivo: Valorar el costo del servicio de hospitalización domiciliaria en comparación a la hospitalización institucional, teniendo en cuenta el perfil epidemiológico y los días estancia. Métodos: Estudio descriptivo, retrospectivo, longitudinal, realizado con pacientes pertenecientes a una compañía de seguros con productos como pólizas de salud y medicina prepagada, que hicieron uso del servicio de hospitalización domiciliaria e institucional en el período comprendido entre enero - diciembre del año 2007. Resultados: Se encontró que el costo de la hospitalización domiciliaria es el 18 % del total del costo de la hospitalización institucional. Se evaluó la diferencia por perfil epidemiológico y por número de días estancia. Conclusiones: La hospitalización domiciliaria es una opción para disminuir el costo de la atención y permite la recuperación del paciente en su entorno

Utilidad del péptido natriurético cerebral en la evaluación de pacientes con falla cardiaca tratados con resincronización cardiaca y su correlación con la evolución clínica Utility of brain natriuretic peptide in patients with heart failure treated with cardiac re-synchronization and its correlation with clinical evolution

La terapia de resincronización cardiaca es una herramienta novedosa y efectiva para el tratamiento de los pacientes con falla cardiaca que no han respondido a medidas farmacológicas óptimas y que además tienen deterioro en su clase funcional y disincronía ventricular. Se ha demostrado que el péptido natriurético cerebral (BNP) determina de manera cuantitativa la severidad de la falla cardiaca y que su concentración sanguínea guarda correlación directamente proporcional con el grado de falla cardiaca. En este trabajo se hace una evaluación prospectiva de los niveles de BNP, función ventricular, clase funcional, evolución clínica, duración del QRS, caminata de seis minutos, hospitalización no programada y mortalidad en los pacientes, antes y a 3, 6 y 9 meses de seguimiento, luego del implante de la terapia de resincronización cardiaca. Se incluyó un total de 34 pacientes quienes se siguieron durante un promedio de nueve meses. Se demostró una disminución en los niveles de BNP (645 pg/mL, 320 pg/mL y 147 pg/mL preimplante, a 6 y 9 meses; p Cardiac resynchronization therapy (CRT) is a novel and effective tool for the treatment of patients with severe heart failure (HF), left ventricular systolic dysfunction and desynchrony, that have not responded to the optimal pharmacological therapy. It has been demonstrated that brain natriuretic peptide (BNP) quantitative determines severity of the HF and their blood levels keep direct proportional correlation to the severity of HF. We prospectively evaluated levels of brain natriuretic peptide (BNP), left ventricular function, New York Heart Association (NYHA) class, QRS duration, and 6-minute hall walk test in a group of patients before biventricular device implantation at 3-6 and 12 months of follow-up. Clinical evolution, not programmed hospitalization and mortality were also evaluated. A total of 34 patients were enrolled and followed for a mean of nine months. A decrease in BNP levels (645 pg/ml, 320 pg/ml and 147 pg/ml pre-implant, 6 months and 9 months respectively. p < 0.0001) was demonstrated; improvement in ventricular function (LVEF 23% vs. 31% p < 0.002), NYHA class (3.53 vs. 1.97 p < 0.0001), QRS duration (142 msec. vs. 116 msec. p < 0.0001) and 6-minute hall walk test (150 meters vs. 328 meters p < 0.0001). Hospitalization rate was 38% and mortality rate was 8.8%. Conclusions: levels of BNP in patients with CRT decrease significantly and keep relationship with the clinical, electrocardiographic and echocardiographic evolution of HF, being useful as prognostic marker and follow-up tool in these patients