Manejo responsable de los desechos radiactivos en la Universidad de Costa Rica

The Radiation Safety Program (RSP) of the University of Costa Rica established in 1990, handles the radioactive waste generated at the University. A centralized storage waste room is used by the Atomic, Nuclear and Molecular Research Center, Health Research Institute, Molecular and Cellular Biology Research Center and the Environmental Contamination Research Center. The RSP has pre-storage procedures, internal controls, protocols for storage, withdrawal of sources and discharges to the environment, according to national and international legislation. The main radionuclides in liquid and solid wastes are P32, I125, S35 y C14; which after a storage period will be disposed of as exempted materials. The waste room also permanently stores sources with the following radionuclides Cs137, U238, Th232, Sr90, Ra226, Cd109, Cf252 and Am241. It has 96 permanent sources and 52 that will be disposed of. The RSP allows the University to have a centralized facility for the safe management of all radioactive waste generated locally. 

On the data-driven description of lattice materials mechanics

In the emerging field of mechanical metamaterials, using periodic lattice structures as a primary ingredient is relatively frequent. However, the choice of aperiodic lattices in these structures presents unique advantages regarding failure, e.g., buckling or fracture, because avoiding repeated patterns prevents global failures, with local failures occurring in turn that can beneficially delay structural collapse. Therefore, it is expedient to develop models for computing efficiently the effective mechanical properties in lattices from different general features while addressing the challenge of presenting topologies (or graphs) of different sizes. In this paper, we develop a deep learning model to predict energetically-equivalent mechanical properties of linear elastic lattices effectively. Considering the lattice as a graph and defining material and geometrical features on such, we show that Graph Neural Networks provide more accurate predictions than a dense, fully connected strategy, thanks to the geometrically induced bias through graph representation, closer to the underlying equilibrium laws from mechanics solved in the direct problem. Leveraging the efficient forward-evaluation of a vast number of lattices using this surrogate enables the inverse problem, i.e., to obtain a structure having prescribed specific behavior, which is ultimately suitable for multiscale structural optimization problems

La enseñanza de la Historia de Cuba: un reto para la Universidad Médica

Introduction: the teaching of the History of Cuba has been a priority for the Cuban revolution, a premise for its ideological support, a basic condition to defend the unity of our people in such a way that it is included in all levels of education in our country and guarantees that our children and youngsters incorporate it since their early ages, first through notions and representations and then through its laws and regularities, that is why the history of Cuba, like no other discipline, has this advantage. Objective: to deep into the influence of the media and its negative impact on the teaching of the History of Cuba at the Medical University. Method: it was performed an exhaustive analysis of several historical issues related to the programs of Cuban History that are taught in our schools and located on digital sites like Wikipedia, which is one of the mostly used by our students. Development: for the analysis it was chosen the Wikipedia digital site and the sample included 10 Historical facts from the ones discussed in our classes, and none of them is properly treated. Conclusions: the use of digital sites can not be the first or the only option to be used by our students for their preparation in the History of Cuba even though sometimes it seems to be easier.Introducción: la enseñanza de la Historia de Cuba ha constituido una prioridad para la revolución cubana, una premisa para el sostén ideológico de la misma, una condición básica para defender la unidad de nuestro pueblo. De tal modo que incluida en todos los niveles de enseñanza en nuestro país va garantizando que nuestros niños y jóvenes la incorporen desde edades tempranas, primero a través de nociones y representaciones y luego a través de sus leyes y regularidades, por lo que la Historia de Cuba como ninguna otra disciplina tiene esta ventaja.Objetivo: profundizar en la influencia de los medios de información y su repercusión negativa en la enseñanza de la Historia de Cuba en la universidad médica.Método: se realizó una revisión exhaustiva de varios temas históricos relacionados con los programas de Historia de Cuba que se imparten en nuestra enseñanza que están ubicados en sitios digitales como Wikipedia que es uno de los más utilizados por nuestros estudiantes.Desarrollo: se escogió como sitio para el análisis el sitio digital Wikipedia y se tomaron como muestra 10 hechos históricos de los que tratamos en nuestras clases, y de ellos ninguno trata adecuadamente.Conclusiones: el uso de los sitios digitales no puede ser ni la primera, ni la única  opción que utilicen nuestros estudiantes,  para la preparación en las asignaturas de Historia de Cuba aunque en ocasiones parezca más  fácil

Restoration of Adiponectin Pulsatility in Severely Obese Subjects After Weight Loss

Diurnal variations of adiponectin levels have been studied in normal-weight men and in diabetic and nondiabetic obese subjects, but no data have been reported in obese subjects after weight loss. We collected blood samples at 1-h intervals over 24 h from seven severely obese subjects before and after massive weight loss consequent to surgical operation (bilio-pancreatic diversion [BPD]) to measure adiponectin, insulin, glucose, and cortisol levels. Insulin sensitivity was assessed by euglycemic-hyperinsulinemic clamp (M value). Studies of diurnal variations and pulsatility of adiponectin, insulin, and cortisol were performed. The pulsatility index (PI) of adiponectin increased after BPD from 0.04 to 0.11 μg/min (P = 0.01). Insulin PI significantly increased after the operation (1.50 vs. 1.08 pmol · l–1 · min–1, P = 0.01), while cortisol PI did not significantly change. The adiponectin clearance rate changed from 0.001 ± 10−4 · min−1 before BPD to 0.004 ± 8 · 10−4 · min−1 after BPD (P = 0.03). Insulin clearance increased from 0.006 ± 6 · 10−4 · min−1 before BPD to 0.009 ± 4 · 10−4 · min−1 after BPD (P = 0.02). The M value doubled after surgery (27.08 ± 8.5 vs. 53.34 ± 9.3 μmol · kgFFM−1 · min−1; P < 0.001) becoming similar to the values currently reported for normal-weight subjects. In conclusion, in formerly severely obese subjects, weight loss paired with the reversibility of insulin resistance restores homeostatic control of the adiponectin secretion, contributing to the reduction of cardiovascular risk already described in these patients

Predictors of weight loss and reversal of comorbidities in malabsorptive bariatric surgery

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Underwater Communication Using Acoustic Parametric Arrays

[EN] This paper presents a study of different types of parametric signals with application to submarine acoustic telecommunications. In all of them, the carrier frequency is 200 kHz, which corresponds to that resonation of the transducer under study, while they differ by the different modulations they present. In this sense, we study modulations with sweeps (4 to 40 kHz), in which represent binary codes (zeros and ones), getting closer to the application in acoustic telecommunications. The different properties of the transmitting signals in terms of communication speed, directivity, efficiency and power needed are discussed as well.We acknowledge the financial support of Plan Estatal de Investigación, ref. FPA2015-65150-C3-2-P (MINECO/FEDER), and of the Generalitat Valenciana, Grant PrometeoII/2014/079.Ardid Ramírez, M.; Campo-Valera, MM.; Tortosa, DD.; Felis-Enguix, I.; Llorens Alvarez, CD.; Martínez Mora, JA. (2018). Underwater Communication Using Acoustic Parametric Arrays. Proceedings. 2(139):1-7. https://doi.org/10.3390/ecsa-4-04907S17213

Massive Weight Loss Decreases Corticosteroid-Binding Globulin Levels and Increases Free Cortisol in Healthy Obese Patients An adaptive phenomenon?

OBJECTIVE—Obesity, insulin resistance, and weight loss have been associated with changes in hypothalamic-pituitary-adrenal (HPA) axis. So far, no conclusive data relating to this association are available. In this study, we aim to investigate the effects of massive weight loss on cortisol suppressibility, cortisol-binding globulin (CBG), and free cortisol index (FCI) in formerly obese women. RESEARCH DESIGN AND METHODS—Ten glucose-normotolerant, fertile, obese women (BMI >40 kg/m2, aged 38.66 ± 13.35 years) were studied before and 2 years after biliopancreatic diversion (BPD) when stable weight was achieved and were compared with age-matched healthy volunteers. Cortisol suppression was evaluated by a 4-mg intravenous dexamethasone suppression test (DEX-ST). FCI was calculated as the cortisol-to-CBG ratio. Insulin sensitivity was measured by an euglycemic-hyperinsulinemic clamp, and insulin secretion was measured by a C-peptide deconvolution method. RESULTS—No difference was found in cortisol suppression after DEX-ST before or after weight loss. A decrease in ACTH was significantly greater in control subjects than in obese (P = 0.05) and postobese women (P ≤ 0.01) as was the decrease in dehydroepiandrosterone (P ≤ 0.05 and P ≤ 0.01, respectively). CBG decreased from 51.50 ± 12.76 to 34.33 ± 7.24 mg/l (P ≤ 0.01) following BPD. FCI increased from 11.15 ± 2.85 to 18.16 ± 6.82 (P ≤ 0.05). Insulin secretion decreased (52.04 ± 16.71 vs. 30.62 ± 16.32 nmol/m−2; P ≤ 0.05), and insulin sensitivity increased by 163% (P ≤ 0.0001). Serum CBG was related to BMI (r0 = 0.708; P = 0.0001), body weight (r0 = 0.643; P = 0.0001), body fat percent (r0 = 0.462; P = 0.001), C-reactive protein (r0 = 0.619; P = 0.004), and leptin (r0 = 0.579; P = 0.007) and negatively to M value (r0 = −0.603; P = 0.005). CONCLUSIONS—After massive weight loss in morbidly obese subjects, an increase of free cortisol was associated with a simultaneous decrease in CBG levels, which might be an adaptive phenomenon relating to environmental changes. This topic, not addressed before, adds new insight into the complex mechanisms linking HPA activity to obesity

Simulación y diseño de un sensor acústico piezoeléctrico para detección de partículas

[EN] Bubble chambers used in detectors for detecting dark matter use piezoelectric sensors in order to detect and discriminate the acoustic signals from bubbles growth in the superheated liquid when a particle interaction occurs. The Research Group in Applied Acoustics to Astroparticles Detection from UPV developed a particle detector, whose acoustic sensors are attached to the outer walls of the chamber. In order to optimize the operation of the sensor, both analytical and numerical models are developed, as well as experimental tests for characterization of sensors design were performed. The results of these studies allows a particular design criterion for the construction of such sensor for future dark matter bubble chamber detectors.[ES] Las cámaras de burbujas empleadas en los detectores para la detección de materia oscura, utilizan sensores piezoeléctricos para detectar y discriminar las señales acústicas emitidas por las burbujas que se generan a partir de la interacción de partículas con el fluido sobrecalentado presente en el interior de dicha cámara. El grupo de Investigación en Acústica Aplicada a la Detección de Astropartículas de la UPV ha desarrollado un modelo de detector de partículas, cuyos sensores acústicos se encuentran pegados en las paredes exteriores de la cámara. Con el objetivo de entender el comportamiento y optimizar el funcionamiento del sensor, se desarrollan modelos analíticos y numéricos, así como pruebas experimentales para su caracterización. Los resultados de estos estudios permiten tener un criterio de diseño para la adecuada construcción de tales sensores en futuras cá- maras de burbujas para la detección de materia oscuraCampo-Valera, MM.; Ardid Ramírez, M.; Felis-Enguix, I.; Martínez Mora, JA. (2018). Simulación y diseño de un sensor acústico piezoeléctrico para detección de partículas. Revista de Acústica. 49(1-2):11-18. http://hdl.handle.net/10251/102342S1118491-

Influence of Maternal Obesity on Insulin Sensitivity and Secretion in Offspring

OBJECTIVE—The purpose of this study was to clarify the effects of maternal obesity on insulin sensitivity and secretion in offspring