Human oocytes and zygotes are ready for ultra-fast vitrification after 2 minutes of exposure to standard CPA solutions

Vitrification of human oocytes and embryos in different stages of development is a key element of daily clinical practice of in vitro fertilization treatments. Despite the cooling and warming of the cells is ultra-fast, the procedure as a whole is time consuming. Most of the duration is employed in a long (8–15 minutes), gradual or direct exposure to a non-vitrifying cryoprotectant solution, which is followed by a short exposure to a more concentrated vitrifying solution. A reduction in the duration of the protocols is desirable to improve the workflow in the IVF setting and reduce the time of exposure to suboptimal temperature and osmolarity, as well as potentially toxic cryoprotectants. In this work it is shown that this reduction is feasible. In silico (MatLab program using two-parameter permeability model) and in vitro observations of the oocytes’ osmotic behaviour indicate that the dehydration upon exposure to standard cryoprotectant solutions occurs very fast: the point of minimum volume of the shrink-swell curve is reached within 60 seconds. At that point, intracellular water ejection is complete, which coupled with the permeation of low molecular weight cryoprotectants results in similar intracellular and extracellular solute concentrations. This shows that prolonging the exposure to the cryoprotectant solutions does not improve the cytosolic glass forming tendency and could be avoided. To test this finding, human oocytes and zygotes that were donated for research were subjected to a shortened, dehydration-based protocol, consisting of two consecutive exposures of one-minute to two standard cryoprotectant solutions, containing ethylene glycol, dimethyl sulfoxide and sucrose. At the end of this two-minute dehydration protocol, the critical intracellular solute concentration necessary for successful vitrification was attained, confirmed by the post-warming survival and ability to resume cytokinesis of the cells. Further studies of the developmental competency of oocytes and embryos would be necessary to determine the suitability of this specific dehydration protocol for clinical practice, but based on our results, short times of exposure to increasingly hypertonic solutions could be a more time-efficient strategy to prepare human oocytes and embryos for vitrification

Puente Cañas

En la carretera de Trinidad a Cienfuegos, provincia de Las Villas (Cuba), se ha construido un puente isostático sobre el río Cañas, de hormigón pretensado, de tres tramos, cuya sección transversal es celular de tres tabiques formando un doble cajón. Los dos tramos laterales o accesos al central, de 15,5 m de luz cada uno, se han construido en voladizo respecto a los dos apoyos centrales. El tramo central salva un vano de 76 m

ESTADOS FINANCIEROS: COMPETENCIA CONTABLE BÁSICA EN LA FORMACIÓN DE CONTADORES PÚBLICOS AUTORIZADOS

This article addresses, from the theoretical point of view and through the approaches of different authors, what are the financial statements, which are the best known and who are their users; as a basic competence in the professional training of public accountants in Panama. For the design of the proposal, a literature review was carried out through two phases, a convergent one that consisted of searches in Google Scholar using as keywords: "Financial statements and accounting competencies", without time restrictions. Those selected documents were re-filtered using the relevance of the approaches between conceptions and the usefulness given to users as a criterion. Subsequently, the analysis of the filtered documents was carried out and coincidences between them were identified. A correct analysis of the financial state of the company guides the decision making of the current situation of the company: investment, financing, action plans; as well as predicting its future performance.En el presente artículo se aborda, desde el punto de vista teórico y a través de los planteamientos de diferentes autores, qué son los estados financieros, cuáles son los más conocidos y quiénes son sus usuarios; como competencia básica en la formación profesional de contadores públicos en Panamá. Para el análisis documental se realizó una revisión de literatura mediante dos fases, una convergente que consistió en búsquedas en Google Académico utilizando como palabras clave: “Estados financieros y competencias contables”, sin restricciones de tiempo. La fase divergente consistió en la selección de los documentos cuyos títulos y resúmenes tuvieran mayor relación con concepciones y descripciones de estados financieros en formación profesional. Esos documentos se volvieron a filtrar utilizando como criterio la utilidad dado para los usuarios. Un correcto análisis del estado financiero de la empresa orienta la toma de decisiones de la situación actual de la empresa: inversión, financiamiento, planes de acción; así como predecir el desempeño futuro de la misma. &nbsp

Spatial wave intensity correlations in quasi-one-dimensional wires

Spatial intensity correlations between waves transmitted through random media are analyzed within the framework of the random matrix theory of transport. Assuming that the statistical distribution of transfer matrices is isotropic, we found that the spatial correlation function can be expressed as the sum of three terms, with distinctive spatial dependences. This result coincides with the one obtained in the diffusive regime from perturbative calculations, but holds all the way from quasi-ballistic transport to localization. While correlations are positive in the diffusive regime, we predict a transition to negative correlations as the length of the system decreases.Comment: 10 pages, 3 figures. Submitted to Physical Review Letter

A discussion on the origin of quantum probabilities

We study the origin of quantum probabilities as arising from non-Boolean propositional-operational structures. We apply the method developed by Cox to non distributive lattices and develop an alternative formulation of non-Kolmogorovian probability measures for quantum mechanics. By generalizing the method presented in previous works, we outline a general framework for the deduction of probabilities in general propositional structures represented by lattices (including the non-distributive case).Fil: Holik, Federico Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; ArgentinaFil: Sáenz, Manuel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Plastino, Ángel Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Las Islas Baleares. Departamento de Física. Instituto de Física Interdisciplinar y Sistemas Complejos; España. Consejo Superior de Investigaciones Científicas. Instituto de Física Interdisciplinar y Sistemas Complejos; Españ