Rotational dynamics in the plastic-crystal phase of ethanol: Relevance for understanding the dynamics during the structural glass transition

The reorientational dynamics within the rotationally disordered cubic plastic phase of solid ethanol is investigated by means of the concurrent use of computer molecular dynamics and quasielastic neutron scattering. Motions involving widely different time scales are shown to take place above the calorimetric "glass transition" which is centered at Tg≈97 K. These correspond to well-defined reorientations belonging to the cubic point group. The dynamics of this solid exhibits features remarkably close to those of the supercooled liquid that can exist at the same temperature. Such similitude of dynamic behavior serves to provide some clues for the understanding of the nature of molecular motions at temperatures close to the canonical liquid→glass transitio

Joint Distribution of Distance and Angles in Finite Wireless Networks

Directional beamforming will play a paramount role in 5G and beyond networks in order to combat the higher path losses incurred at millimeter wave bands. Appropriate modeling and analysis of the angles and distances between transmitters and receivers in these networks are thus essential to understand performance and limiting factors. Most existing literature considers either infinite and uniform networks, where nodes are drawn according to a Poisson point process, or finite networks with the reference receiver placed at the origin of a disk. Under either of these assumptions, the distance and azimuth angle between transmitter and receiver are independent, and the angle follows a uniform distribution between $0$ and $2\pi$. Here, we consider a more realistic case of finite networks where the reference node is placed at any arbitrary location. We obtain the joint distribution between the distance and azimuth angle and demonstrate that these random variables do exhibit certain correlation, which depends on the shape of the region and the location of the reference node. To conduct the analysis, we present a general mathematical framework which is specialized to exemplify the case of a rectangular region. We then also derive the statistics for the 3D case where, considering antenna heights, the joint distribution of distance, azimuth and zenith angles is obtained. Finally, we describe some immediate applications of the present work, including the analysis of directional beamforming, the design of analog codebooks and wireless routing algorithms.Comment: 14 pages, 14 figure

Purely dynamical signature of the orientational glass transition

The dynamics of the freezing transition of the rotator phase crystal of ethanol into its orientational glass phase is monitored by measurements of molecular rotational components in the quasielastic neutron scattering spectrum. We demonstrate that phenomena observed at pico- and nanosecond scales can be mapped onto those shown by a model of infinitely thin hard needles rotating around body-centered-cubic lattice positions. As the model glass transition is of purely dynamical origin, our findings support the idea that the glass transition is purely dynamical and not associated with any thermodynamic phase transition.Dirección General de Investigación Científica y Técnica PB95-0075-C03-0

Role of low-frequency vibrations on sound propagation in glasses at intermediate temperature

We report measurements of the temperature dependence of the sound attenuation and the fractional change in sound velocity for the glass (G) and orientational-glass (OG) phases of polymorphic ethanol. Strikingly similar behaviors are found for both phases despite the OG's underlying crystal (bcc) lattice. Such similarity, which is also revealed in dielectric spectroscopy and inelastic neutron scattering measurements, suggests whole molecule small-angle librations as a common microscopic origin for a wide variety of "glassy" phenomena.Dirección General de Investigación Científica y Técnica PB95-0075-C03-0

ECOC 2018

Producción CientíficaA real end-to-end SDN based GPON scenario to provide a fast, efficient and accurate QoS management is proposed. It is designed to support a novel network management model that permits residential users to control their bandwidth network resources.Ministerio de Ciencia e Innovación (Projects TEC2014-53071-C3-2-P, TEC2015-71932-REDT, TEC2017-84423-C3-1-P and TEC2015-67834-R

The mechanism of the transpersulfuration reaction in a cysteine desulfurase-sulfur acceptor model system

Trabajo presentado en las 1as Jornadas Españolas de Biocatálisis, celebradas en Madrid (España) del 02 al 03 de julio de 2015.Escherichia coli CsdA cysteine desulfurase (the sulfur donor) and the CsdE sulfur acceptor are involved in biological sulfur trafficking, in iron-sulfur cluster assembly, and tRNA hypermodification [1] in the model bacterium Escherichia coli. CsdA and CsdE form a stable complex through a polar interface. Although mechanisms for the transfer of a sulfur moiety across protein-protein interfaces have been proposed based on the IscS-IscU and IscS-TusA structures [2,3], the flexibility of the catalytic Cys loops involved has precluded a high resolution view of the active-site geometry and chemical environment responsible to facilitate sulfur transfer. Here, we have used a combination of X-ray crystallography, solution NMR, biophysical and computational chemistry methods to unravel how CsdA provides a specific recognition platform for CsdE and how their complex organizes a composite functional reaction environment. A mechanistic view of sulfur transfer across protein-protein interfaces emerges from the structural analysis of the CSD system

Theorical analysis to explain the slow acceptance of the recent residential vertical trends in San José, Costa Rica

O artigo tem como objetivo avaliar o surgimento e evolução do mercado imobiliário costarriquenho com o intuito de desvendar o contexto do forte vínculo com a terra e, por conseguinte, propor uma explicação ao lento aceite das novas tendências residenciais verticais. A metodologia consiste em pesquisas de campo anuais entre 2011 e 2017, revisão de fotografias e uma revisão bibliográfica de autores marxistas costarriquenhos, brasileiros e internacionais, com a intenção de formular uma discussão teórica para mostrar como as mudanças nos modos de produção e na economia local fortaleceram a relação entre a população e sua terra. Utiliza-se um amplo recorte temporal desde o período colonial até a atualidade com o intuito de analisar como, ao longo da evolução do mercado imobiliário, as diferentes formas de moradia permitiram manter esse forte arraigo pela terra. Posteriormente aborda-se o tema da recente verticalização residencial de luxo e se realiza uma análise semântica dessa, com a intenção de entender a reação da população frente a uma proposta residencial sem acesso a jardim ou espaço ao ar livre. Conclui-se que, embora possam existir outros fatores, o forte arraigo pela terra pode ser considerado um dos motivos principais do lento aceite dos novos empreendimentos verticais na Costa Rica.This article aims to evaluate the emergence and evolution of the Costa Rican real estate market in order to unravel the context of the strong bond with the land and hence the slow acceptance of new residential vertical trends. The methodology consists of annual fieldworks between 2011 and 2017, a revision of some local antique urban photographs and a bibliographical review of Costa Rican, Brazilian and international Marxist authors, with the purpose of formulating a theoretical discussion to show how changes in the modes of production and the local economy strengthened the relationship between people and their land. A broad time frame is analyzed, from the colonial period until nowadays, in order to examine, how across the course of the evolution of the real estate market, the different forms of housing have adapted to preserve the strong attachment that the population has had for their land. Afterward, the issue of the recent emergence of luxury vertical buildings is addressed and a semantic analysis is done to examine the population´s response to the new residential proposal without access to open space. It is concluded the strong attachment to the land may be one of the main reasons for the slow acceptance of new vertical developments in Costa Rica, even though there might exist other factors.Universidad de Costa Rica/[]/UCR/Costa RicaUniversidade Federal de Santa Catarina/[]/UFSC/BrasilUCR::Vicerrectoría de Docencia::Ciencias Sociales::Facultad de Ciencias Sociales::Escuela de Geografí

Chitosan/Poly(Dllactide-Co-Glycolide) Scaffolds for Tis- sue Engineering

Abstract Chitosan/poly(DL-lactide-co-glycolide) (Ch/DL PLG) composite scaffolds were fabricated by freeze-drying lyophilization, and were evaluated and compared for use as a bone regeneration scaffold through measurements of the compression mechanical properties of the porous scaffolds. Also, In vitro cell culture of Sprague-Dawley rat's osteoblasts were used to evaluate the phenotype expression of cells in the scaffolds, characterizing the cellular adhesion, proliferation and alkaline phosphatase activity. The gene expression of osteocalcin, sialoprotein, alkaline phosphatase, Type I collagen and TGFb1 were confirmed in the samples; moreover, it was confirmed, the mineralization by IR spectra and EDS analysis. Our results thus show that Ch/DL PLG scaffolds are suitable for biological applications

Immediate effects of dasatinib on the migration and redistribution of naïve and memory lymphocytes associated with lymphocytosis in chronic myeloid leukemia patients

Introduction: Dasatinib is a dual SRC/ABL tyrosine kinase inhibitor used to treat chronic myeloid leukemia (CML) that is known to have unique immunomodulatory effects. In particular, dasatinib intake typically causes lymphocytosis, which has been linked to better clinical response. Since the underlying mechanisms are unknown and SRC family kinases are involved in many cell motility processes, we hypothesized that the movement and migration of lymphocytes is modulated by dasatinib. Patients, Materials and Methods: Peripheral blood samples from CML patients treated with second-line dasatinib were collected before and 2 h after the first dasatinib intake, and follow-up samples from the same patients 3 and 6 months after the start of therapy. The migratory capacity and phenotype of lymphocytes and differential blood counts before and after drug intake were compared for all study time-points. Results: We report here for the first time that dasatinib intake is associated with inhibition of peripheral blood T-cell migration toward the homeostatic chemokines CCL19 and CCL21, which control the trafficking toward secondary lymphoid organs, mainly the lymph nodes. Accordingly, the proportion of lymphocytes in blood expressing CCR7, the chemokine receptor for both CCL19 and CCL21, decreased after the intake including both naïve CD45RA+ and central memory CD45RO+ T-cells. Similarly, naïve B-cells diminished with dasatinib. Finally, such changes in the migratory patterns did not occur in those patients whose lymphocyte counts remained unchanged after taking the drug. Discussion: We, therefore, conclude that lymphocytosis induced by dasatinib reflects a pronounced redistribution of naïve and memory populations of all lymphocyte subsets including CD4+ and CD8+ T-cells and B-cells