Science.gov

Sample records for radicales libres mediante

  1. Detección y estudio mediante Fluorescencia Inducida por Láser de radicales libres formados por Disociación Multifotónica Infrarroja

    NASA Astrophysics Data System (ADS)

    Santos, M.; Díaz, L.; Torresano, J. A.; Rubio, L.; Samoudi, B.

    Una de las principales aplicaciones actuales de los procesos de disociación multifotónica inducidos por radiación láser infrarroja (DMI) es la producción de radiales libres, con el fin de estudiar sus propiedades cinéticas y espectroscópicas. La disociación de moléculas poliatómicas en el IR con láseres de CO2 tiene lugar desde la superficie de energía molecular mas baja y conduce generalmente a la formación de fragmentos en el estado electrónico fundamental, con diversos grados de excitación vibracional. En el Grupo de Procesos Multifotónicos del Instituto de Estructura de la Materia del C.S.I.C. hemos puesto a punto la técnica de Fluorescencia Inducida por Láser (LIF) para la detección y análisis en tiempo real de los fragmentos producidos en la DMI inducida mediante uno o dos campos láseres de diferentes longitudes de onda. Objetivos de nuestro trabajo han sido el estudio de los canales de disociación mayoritarios y de las especies transitoria producidas, así como de la distribución de energía interna con que éstas son generadas. En particular hemos detectado mediante LIF las especies: C2, CF, CH, SiH2, CF2, CH2, SiHCl, y CF3 a partir de la disociación de, entre otras, las siguientes moléculas: C2H3Br, C3F6, C4H8Si, C2H5ClSi y CH5ClSi. En este trabajo presentamos algunos de los resultados obtenidos mediante el estudio por LIF de estos radicales: estudio temporal de la señal LIF obtenida con determinación de tiempos de vida, espectros de excitación y fluorescencia, temperaturas vibracionales de formación, variación de la intensidad LIF con el tiempo de retraso entre los láseres de disociación y prueba, etc.

  2. "Entre libre" dans la classe ("Entre Libre" in the Classroom).

    ERIC Educational Resources Information Center

    Compte, Carmen

    1987-01-01

    In an interview, two teachers describe and discuss their different classroom use of the same set of instructional materials for "Entre Libre" and compare the results. Activities include role playing, music, and reporting. (MSE)

  3. Comment on "Radicalicity: A scale to compare reactivities of radicals" (Chem. Phys. Lett. 618 (2015) 99-101)*

    DOE PAGESBeta

    Poutsma, Marvin L.

    2016-04-21

    The recently proposed term radicalicity was described as a measure of the reactivity of a free radical Q*, i.e., a kinetic quantity. Here it is shown that in fact it is simply a frame-shifted version of the well-known bond dissociation energy, a thermodynamic quantity. Hence its use is discouraged.

  4. LIBRE Model: Engagement Styles in Counseling

    ERIC Educational Resources Information Center

    Guerra, Norma S.

    2007-01-01

    Engagement is essential for the processing of information. It is presented here as 2 points along a continuum: initial attention (primary self-presentation) and sustained attention (continued self-regulation). The LIBRE (Listen, Identify, Brainstorm, Reality Test, Encourage) Stick Figure Tool (N. S. Guerra, 2003) provides a graphic organizer for…

  5. Libre: A Framework for Sharing and Discovering Science Data

    NASA Astrophysics Data System (ADS)

    Lacy, J.; Duerr, R. E.

    2010-12-01

    To enable peer review and re-use, data must be publicly shareable and discoverable. The Libre project within the NSIDC, in conjunction with other members of the Federation of Earth Science Information Partners and the Polar Information Commons, provides a framework for collaborative publishing of open science data. This talk describes the Libre framework as a model for “freeing” science data. Libre uses technologies such as Atom feeds to enable syndication of data sets and services. Open Search services allow the feeds to be discovered. An aggregator, like a news reader, provides notice for new or changed data sets and services. With these technologies, the Libre project provides both open-source tooling and a road map for similar efforts in other fields.

  6. LiBr passivation effect of porous nanocrystalline hydrogenated silicon

    NASA Astrophysics Data System (ADS)

    Amor, Sana Ben; Haddadi, Ikbel; Seif, El Whibi; Daik, Ridha; Bousbih, Rabaa; Dimassi, Wissem; Ezzaouia, Hatem

    2015-12-01

    Nanocrystalline hydrogenated silicon (nc-Si:H) films were deposited on a p-type silicon substrate by plasma enhanced chemical vapor deposition (PECVD), using SiH4 and H2 as reactive gases. Porous (nc-Si:H) layers were afterward obtained and immersed in a lithium bromide (LiBr) aqueous solution in order to enhance their optical and electrical properties for a potential solar cells application. A decrease in the reflectivity to about 9% for Li/porous nc-Si:H layer deposited at 75 sccm against an increase in the minority carrier lifetime were obtained. We correlate these results to the change in crystalline characteristics and chemical composition of the layers in order to understand the effect of LiBr coating on nc-Si:H Through optical and electrical characterization we have demonstrated the possibility of using such LiBr treatment to improve the properties of porous nc-Si:H.

  7. Reform in Spanish Education: The Institucion Libre de Ensenanza.

    ERIC Educational Resources Information Center

    Valis, Noel M.

    This document examines the development and influence of the Free Institute of Education (Institucion Libre de Ensenanza) and of its founder, Don Francisco Giner de los Rios, in late nineteenth century Spain. Founded in 1876 against a background of repression and reimposition of state-controlled education during the Bourbon Restoration the…

  8. Magnetic stratigraphy of Peralkaline Volcanism in Sierra Libre, Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Olguin-Villa, A. E.; Stock, J. M.; Vidal-Solano, J. R.

    2011-12-01

    Middle Miocene (~12 Ma) magmatism in NW Mexico was dominated by the appearance of anorogenic liquids associated with the Proto-Gulf of California. These correspond to a few occurrences of mafic volcanic rocks with transitional signatures (geochemically) and to a larger silicic volcanic event of peralkaline affinity. The silicic event is primarily composed of a large ignimbritic deposit widely recognized in Baja California as the Tuff of San Felipe (TSF), and in Sonora as the Hermosillo Ignimbrite. These are correlated by a number of characteristics including a unique low-inclination, reversed magnetization, probably associated with a field transition or a geomagnetic excursion within a reversed polarity subchron at 11.531-11.935 Ma (base of C5r.3r; Cande and Kent, 1995). Thick sections of deposits of this peralkaline volcanism crop out at Sierra Libre, geographically located ~45 km south of Hermosillo, Sonora. In this locality, a ~180m thick stack of middle Miocene volcanic units (both pyroclastic and lavas) were sampled for paleomagnetic studies focusing on the magnetic stratigraphy of a set of 9 units (7 to 12 cores per unit) from El Galindro Canyon, which represents the thickest volcanic pile genetically related to Tuff of San Felipe and Hermosillo ignimbrite. Previous studies indicated that the anomalous magnetization from TSF could be either an excursion or a reversal transition - its age is unconstrained except by direct radiological isotopes and relative stratigraphy. But most excursions recorded in high-deposition rate lakebeds, and less often in volcanic piles, trace simple "there-and-back" paths away from and returning to the ordinary geomagnetic secular variation locus for an age. By contrast, the Sierra Libre magnetizations wander erratically in declination and inclination, without following a simple sequential ''Path''. Polarity reversal transitions recorded in high-deposition rate lakebeds do behave that way. We therefore interpret TSF (and remarkably

  9. LIBRE Stick Figure Tool: A Graphic Organizer to Foster Self-Regulated Social Cognitive Problem Solving

    ERIC Educational Resources Information Center

    Guerra, Norma S.

    2009-01-01

    Graphic organizers are powerful visual tools. The representation provides dimension and relationship to ideas and a framework for organization and elaboration. The LIBRE Stick Figure Tool is a graphic organizer for the problem-solving application of the LIBRE Model counseling approach. It resembles a "stick person" and offers the teacher and…

  10. Crawling The Web for Libre: Selecting, Integrating, Extending and Releasing Open Source Software

    NASA Astrophysics Data System (ADS)

    Truslove, I.; Duerr, R. E.; Wilcox, H.; Savoie, M.; Lopez, L.; Brandt, M.

    2012-12-01

    Libre is a project developed by the National Snow and Ice Data Center (NSIDC). Libre is devoted to liberating science data from its traditional constraints of publication, location, and findability. Libre embraces and builds on the notion of making knowledge freely available, and both Creative Commons licensed content and Open Source Software are crucial building blocks for, as well as required deliverable outcomes of the project. One important aspect of the Libre project is to discover cryospheric data published on the internet without prior knowledge of the location or even existence of that data. Inspired by well-known search engines and their underlying web crawling technologies, Libre has explored tools and technologies required to build a search engine tailored to allow users to easily discover geospatial data related to the polar regions. After careful consideration, the Libre team decided to base its web crawling work on the Apache Nutch project (http://nutch.apache.org). Nutch is "an open source web-search software project" written in Java, with good documentation, a significant user base, and an active development community. Nutch was installed and configured to search for the types of data of interest, and the team created plugins to customize the default Nutch behavior to better find and categorize these data feeds. This presentation recounts the Libre team's experiences selecting, using, and extending Nutch, and working with the Nutch user and developer community. We will outline the technical and organizational challenges faced in order to release the project's software as Open Source, and detail the steps actually taken. We distill these experiences into a set of heuristics and recommendations for using, contributing to, and releasing Open Source Software.

  11. Commande optimale à flux libre des machines asynchrones

    NASA Astrophysics Data System (ADS)

    Biedinger, J. M.; Poullain, S.; Yvon, J. P.

    1992-01-01

    The subject of this paper is the optimal control with unconstrained flux of an induction motor being considered as a distributed parameter system described by a nonlinear diffusion equation. This approach allows to describe the electrodynamic state of the motor by taking into account, in a natural way, the influence of saturation and eddy-currents, as well as the nonlinearities due to the variable flux operation. Equations are approximated via a finite element formulation which leads to a finite dimensional dynamical system to which the techniques of optimal control may be applied. The generality of the methodology allows to treat various criteria. The objective aimed in this paper is to force the motor torque to follow a given input, especially under initially demagnetized conditions and with, naturally, constraints on the currents. For this purpose the criterion will be chosen as a norm of the difference between the electromagnetic torque and a given reference torque. Numerical simulations are presented for the case of a squirrel-cage rotor and for a solid iron rotor. Results are compared with those deduced from strategies based on lumped-parameter models. Torque responses obtained with field-oriented control method adapted to the case of flux-variable operation are also presented. Finally a modification of the criterion is proposed for identifying the command which allows to obtain the larger torque during transient states. Dans cet article on traite le problème du contrôle optimal à flux libre d'un moteur asynchrone considéré comme un système à paramètres répartis gouverné par une équation de diffusion non linéaire. Cette approche permet de décrire l'état électrodynamique de la machine en prenant naturellement en compte les effets de la saturation et des courants induits, ainsi que les non-linéarités liées au fonctionnement à flux variable. La formulation éléments finis est utilisée pour traduire le problème continu sous la forme d

  12. Preservice Teachers' Problem Solving: A Study of Problem Identification and Engagement Style Using the LIBRE Model

    ERIC Educational Resources Information Center

    Castro-Villarreal, Felicia; Guerra, Norma S.

    2012-01-01

    In this study, we examine 122 preservice teachers' reported problems and assessed engagement styles using the LIBRE model stick figure. Qualitative and descriptive data were gathered using (1) a qualitative problem-solving activity to identify preservice teachers' problems and engagement preferences and (2) descriptive analyses to depict and…

  13. Libre Systems: Making Data and Software More Available Through Re-usable Components

    NASA Astrophysics Data System (ADS)

    Lewis, S.; Lacy, J.; Reed, S.; Truslove, I.; Lopez, L.; McNulty, M.; Wu, H.; Duerr, R. E.

    2011-12-01

    With the amount of stored data increasing at an exponential rate, it is becoming increasingly important for scientists and data managers to find effective ways to allow users to discover and use data effectively. Sharing software tools to assist in this effort is also becoming more vital in making this a reality. The National Snow and Ice Data Center's Libre project is solving this by creating a system of components including an aggregator, which will allow users to find data and services matching specified criteria more easily. While making it flexible enough to ingest metadata from various sources is important, it is also important to make the concepts and actual software components available to others who wish to make their data and services more discoverable and accessible. The Libre system is designed to make this a reality, by componentizing the underlying mechanisms and thus allowing the pieces to be shared and reused by those who need them. These components can then be tailored to meet specific needs, allowing the individual data providers to avoid wasteful duplication of effort, and focus more on making their data available to the world. This componentization would also allow the data providers to replace specific pieces with other software if desired, while still preserving the overall functionality of the system. When finished, the various components of the Libre system will be released to the open source community, facilitating the easy inclusion and modification of the system, and allowing users to discover data and services more easily.

  14. Absorption characteristics of lithium bromide (LiBr) solution constrained by superhydrophobic nanofibrous structures

    SciTech Connect

    Isfahani, RN; Moghaddam, S

    2013-08-01

    An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at a LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.

  15. 2012 International Conference on Medical Physics and Biomedical Engineering Thermal Economic Analysis on LiBr Refrigeration -Heat Pump System Applied in CCHP System

    NASA Astrophysics Data System (ADS)

    Zhang, CuiZhen; Yang, Mo; Lu, Mei; Zhu, Jiaxian; Xu, Wendong

    LiBr refrigeration cooling water contains a lot of low-temperature heat source, can use this part of the heat source heat boiler feed water. This paper introduced LiBr refrigeration - heat pump system which recovery heat of the LiBr refrigeration cooling water by heat pump system to heat the feed water of boiler. Hot economic analysis on the system has been performed based on the experimental data. Results show that LiBr refrigeration-heat pump system brings 26.6 percent decrease in primary energy rate consumption comparing with the combined heat and power production system(CHP) and separate generation of cold;

  16. LiBr treated porous silicon used for efficient surface passivation of crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Zarroug, Ahmed; Haddadi, Ikbel; Derbali, Lotfi; Ezzaouia, Hatem

    2015-04-01

    A simple but effective passivation method of both front and rear surfaces using porous silicon (PS) has been developed. This paper investigates the effect of LiBr on the passivation of PS. The immersion of as-etched PS in dilute LiBr solution followed by an annealing in an infrared furnace, under a controlled atmosphere at different temperatures, led to the passivation of the PS layer and the improvement of the electronic properties of the crystalline silicon substrates. The influence of substrate temperature was investigated, since the processed wafers were found to be sensitive to heat, which in turn was optimized to have a gettering effect. The bromide of lithium can effectively saturate dangling bonds and hence contributed to the formation of a stable passivation film, at both front and back surfaces. Such a reaction was found to have a beneficial effect on the passivation process of the PS layer grown on both sides. The obtained results exhibited a significant improvement of the minority carrier lifetime, which is an important parameter that defines the quality of crystalline silicon substrates, and an apparent enhancement of its photoluminescence (PL). The internal quantum efficiency was investigated and found to be significantly improved. The qualitative effect of the above-mentioned procedure proved a significant enhancement of the electronic quality of the treated substrates.

  17. Free/Libre Open Source Software Implementation in Schools: Evidence from the Field and Implications for the Future

    ERIC Educational Resources Information Center

    Lin, Yu-Wei; Zini, Enrico

    2008-01-01

    This empirical paper shows how free/libre open source software (FLOSS) contributes to mutual and collaborative learning in an educational environment. Unlike proprietary software, FLOSS allows extensive customisation of software to support the needs of local users better. This also allows users to participate more proactively in the development…

  18. LiCl Dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

    DOEpatents

    Ko, Suk M.

    1980-01-01

    This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system.

  19. LiCl dehumidifier LiBr absorption chiller hybrid air conditioning system with energy recovery

    SciTech Connect

    Ko, S.M.

    1980-06-03

    This invention relates to a hybrid air conditioning system that combines a solar powered LiCl dehumidifier with a LiBr absorption chiller. The desiccant dehumidifier removes the latent load by absorbing moisture from the air, and the sensible load is removed by the absorption chiller. The desiccant dehumidifier is coupled to a regenerator and the desiccant in the regenerator is heated by solar heated hot water to drive the moisture therefrom before being fed back to the dehumidifier. The heat of vaporization expended in the desiccant regenerator is recovered and used to partially preheat the driving fluid of the absorption chiller, thus substantially improving the overall COP of the hybrid system. 4 figs.

  20. Group Maintenance Behaviors of Core and Peripherial Members of Free/Libre Open Source Software Teams

    NASA Astrophysics Data System (ADS)

    Scialdone, Michael J.; Li, Na; Heckman, Robert; Crowston, Kevin

    Group Maintenance is pro-social, discretionary, and relation-building behavior that occurs between members of groups in order to maintain reciprocal trust and cooperation. This paper considers how Free/libre Open Source Software (FLOSS) teams demonstrate such behaviors within the context of e-mail, as this is the primary medium through which such teams communicate. We compare group maintenance behaviors between both core and peripheral members of these groups, as well as behaviors between a group that remains producing software today and one which has since dissolved. Our findings indicate that negative politeness tactics (those which show respect for the autonomy of others) may be the most instrumental group maintenance behaviors that contribute to a FLOSS group’s ability to survive and continue software production.

  1. Fractured bodies and diseased societies: medicalizing Quebec in Cité libre.

    PubMed

    Robert, Julie

    2011-01-01

    This essay seeks to rationalize and explain the evolution of medical rhetoric in Cité libre by looking at trends in the journal's use of tropes of illness and disease. Through a combination of broad content analysis and close readings, it contrasts how individual metaphors create the impression of a sickening nation and the manner in which these metaphors collectively, albeit paradoxically, act as a national allegory of cure for mid-twentieth-century Quebec's social ills in general, and specifically for its pathological inferiority complex. By examining how the journal uses medical metaphors and specifically how the writers employed the trope of the body politic to illustrate Quebec's national failings, the essay demonstrates how Quebec challenges the rhetorical stability of the age-old metaphor as it attempts to solve, but also creates, problems within Quebec's articulation of its own nationhood. PMID:21910268

  2. Effect of B-Mo-W Complex Inhibitor on Corrosion of Mild Steel in 55% LiBr Solution

    NASA Astrophysics Data System (ADS)

    Li, Jielan; Liang, Chenghao; Huang, Naibao

    2015-11-01

    The inhibition effects of B-Mo-W complex inhibitor on corrosion of mild steel in 55% LiBr solution were investigated using weight-loss method, electrochemistry tests, SEM, EDX, and XRD. The ingredients of B-Mo-W complex inhibitor included organic phosphonic acid B, Na2MoO4, and Na2WO4. The results revealed that B-Mo-W complex inhibitor was capable of inhibiting the corrosion of mild steel in 55% LiBr solution, exhibiting high inhibition efficiencies around 97.7%. B-Mo-W complex inhibitor promoted the formation of a protective passive film composed of Fe, Mo, W, and O elements. The passive film decreased the corrosion rate, improved the electrochemistry performance, and enhanced anti-corrosion ability of mild steel.

  3. Physics of lithium bromide (LiBr) solution dewatering through vapor venting membranes

    SciTech Connect

    Isfahani, RN; Fazeli, A; Bigham, S; Moghaddam, S

    2014-01-01

    The physics of water desorption from a lithium bromide (LiBr) solution flow through an array of microchannels capped by a porous membrane is studied. The membrane allows the vapor to exit the flow and retains the liquid. Effects of different parameters such as wall temperature, solution and vapor pressures, and solution mass flux on the desorption rate were studied. Two different mechanisms of desorption are analyzed. These mechanisms consisted of: (1) direct diffusion of water molecules out of the solution and their subsequent flow through the membrane and (2) formation of water vapor bubbles within the solution and their venting through the membrane. Direct diffusion was the dominant desorption mode at low surface temperatures and its magnitude was directly related to the vapor pressure, the solution concentration, and the heated wall temperature. Desorption at the boiling regime was predominantly controlled by the solution flow pressure and mass flux. Microscale visualization studies suggested that at a critical mass flux, some bubbles are carried out of the desorber through the solution microchannels rather than being vented through the membrane. Overall, an order of magnitude higher desorption rate compare to a previous study on a membrane-based desorber was achieved. Published by Elsevier Ltd.

  4. Le consentement libre et éclairé aux soins en psychiatrie

    PubMed Central

    Neilson, Grainne; Chaimowitz, Gary

    2015-01-01

    Résumé Le patient a le droit d’être informé sur les soins de santé qui lui sont proposés et de participer activement à la prise de décisions relativement à ces soins. Le respect de la dignité et de l’autonomie de la personne passe par le respect de son droit de prendre des décisions à propos de ses soins psychiatriques, notamment de refuser un traitement, pour autant qu’elle soit apte à prendre des décisions. Il importe que le psychiatre connaisse les fondements éthiques du consentement libre et éclairé et les exigences prévues par le droit en cette matière, y compris la jurisprudence. Le consentement n’est pas immuable, pouvant changer avec le temps, au fil de l’évolution des conditions et des circonstances. Par conséquent, le consentement doit être un processus continu.

  5. Free/Libre Open Source Software in Health Care: A Review

    PubMed Central

    Schmuhl, Holger; Demski, Hans

    2014-01-01

    Objectives To assess the current state of the art and the contribution of Free/Libre Open Source Software in health care (FLOSS-HC). Methods The review is based on a narrative review of the scientific literature as well as sources in the context of FLOSS-HC available through the Internet. All relevant available sources have been integrated into the MedFLOSS database and are freely available to the community. Results The literature review reveals that publications about FLOSS-HC are scarce. The largest part of information about FLOSS-HC is available on dedicated websites and not in the academic literature. There are currently FLOSS alternatives available for nearly every specialty in health care. Maturity and quality varies considerably and there is little information available on the percentage of systems that are actually used in health care delivery. Conclusions The global impact of FLOSS-HC is still very limited and no figures on the penetration and usage of FLOSS-HC are available. However, there has been a considerable growth in the last 5 to 10 years. While there where only few systems available a decade ago, in the meantime many systems got available (e.g., more than 300 in the MedFLOSS database). While FLOSS concepts play an important role in most IT related sectors (e.g., telecommunications, embedded devices) the healthcare industry is lagging behind this trend. PMID:24627814

  6. Estudio de NIH indica que la actividad física en tiempo libre alarga la vida tanto como 4,5 años

    Cancer.gov

    La actividad física en tiempo libre está asociada con una expectativa de vida más larga, aun en un grado de actividad relativamente bajo e independientemente del peso corporal, de acuerdo con un estudio llevado a cabo por un equipo de investigadores del I

  7. The Presence of the British Education Model in Spain: Reception through the Institución Libre De Enseñanza

    ERIC Educational Resources Information Center

    Fernández-Soria, Juan Manuel

    2014-01-01

    Spain suffered a severe political and moral crisis in the final years of the nineteenth century and the first third of the twentieth. Pedagogues and politicians belonging to the "Institución Libre de Enseñanza" (ILE), or those close to it, did not consider it possible to regenerate the country without attending to education and Britain…

  8. The Synergism Between Heat and Mass Transfer Additive and Advanced Surfaces in Aqueous LiBr Horizontal Tube Absorbers

    SciTech Connect

    Miller, W.A.

    1999-03-24

    Experiments were conducted in a laboratory to investigate the absorption of water vapor into a falling-film of aqueous lithium bromide (LiBr). A mini-absorber test stand was used to test smooth tubes and a variety of advanced tube surfaces placed horizontally in a single-row bundle. The bundle had six copper tubes; each tube had an outside diameter of 15.9-mm and a length of 0.32-m. A unique feature of the stand is its ability to operate continuously and support testing of LiBr brine at mass fractions {ge} 0.62. The test stand can also support testing to study the effect of the failing film mass flow rate, the coolant mass flow rate, the coolant temperature, the absorber pressure and the tube spacing. Manufacturers of absorption chillers add small quantities of a heat and mass transfer additive to improve the performance of the absorbers. The additive causes surface stirring which enhances the transport of absorbate into the bulk of the film. Absorption may also be enhanced with advanced tube surfaces that mechanically induce secondary flows in the falling film without increasing the thickness of the film. Several tube geometry's were identified and tested with the intent of mixing the film and renewing the interface with fresh solution from the tube wall. Testing was completed on a smooth tube and several different externally enhanced tube surfaces. Experiments were conducted over the operating conditions of 6.5 mm Hg absorber pressure, coolant temperatures ranging from 20 to 35 C and LiBr mass fractions ranging from 0.60 through 0.62. Initially the effect of tube spacing was investigated for the smooth tube surface, tested with no heat and mass transfer additive. Test results showed the absorber load and the mass absorbed increased as the tube spacing increased because of the improved wetting of the tube bundle. However, tube spacing was not a critical factor if heat and mass transfer additive was active in the mini-absorber. The additive dramatically affected

  9. Conversion of rat liver S-adenosyl-L-methionine synthetase from high-Mr form to low-Mr form by LiBr.

    PubMed

    Cabrero, C; Alemany, S

    1988-02-10

    Rat liver S-adenosyl-L-methionine synthetase exists in two forms which are, respectively, a dimer and a tetramer of an Mr 48,500 subunit. The high-molecular-mass form is converted into the low-molecular-mass form by incubation with 1.4 M LiBr. The kinetic properties of the low-molecular-mass form obtained by LiBr treatment are the same as those obtained with the low-molecular-mass S-adenosyl-L-methionine synthetase form purified from rat liver cytosol. These results demonstrate that the differences in specific activity and regulatory properties of the high-molecular-mass and the low-molecular-mass S-adenosyl-L-methionine synthetase forms are due to their different polymeric states. PMID:2827780

  10. Modélisation du bruit des jets turbulents libres et subsoniques à température ambiante

    NASA Astrophysics Data System (ADS)

    Béchara, W.; Lafon, P.; Candel, S. M.

    1993-03-01

    Based on the theoretical model of Goldstein for a round free jet, we establish analytical expressions (G_a model) for the noise radiation from a turbulent jet, depending on the local statistical properties of the flow. These characteristics are calculated by solving the Reynolds average Navier-Stokes equations with a numerical code based on a K - \\varepsilon turbulence closure model. A comparison between the numerical results and the experimental data for a simple jet and two coaxial jets shows that this model correctly predicts the evolution of the acoustic radiation. The G_a model developed in the case of axisymmetric turbulence superimposed over a mean flow is found to be more suitable than the Ribner model associated to an isotropic turbulence. A comparison between differents models issued from Lighthill theory, shows that the G_a model yields the best directivity of the acoustic intensity at high jet exit velocities. À partir du modèle théorique proposé initialement par Goldstein pour un jet libre turbulent circulaire, on établit des expressions analytiques (modèle G_a) permettant le calcul du bruit émis à partir des grandeurs statistiques locales du jet turbulent. Ces grandeurs sont estimées par résolution des équations de Navier-Stokes moyennées à l'aide d'un code numérique de turbulence utilisant un modèle de fermeture de type K - \\varepsilon. La comparaison entre les résultats numériques obtenus et les données expérimentales, pour un jet simple et deux jets coaxiaux, montre que ce modèle estime correctement l'évolution des grandeurs acoustiques étudiées. Les calculs indiquent que le modèle G_a développé pour une turbulence axisymétrique convectée par un écoulement moyen est mieux adapté que celui de Ribner associé à une turbulence isotrope. De plus, une comparaison entre différents modèles basés sur la théorie de Lighthill indique que le modèle G_a donne la meilleure directivité de l'intensité acoustique aux

  11. Normative data for the Rappel libre/Rappel indicé à 16 items (16-item Free and Cued Recall) in the elderly Quebec-French population.

    PubMed

    Dion, Mélissa; Potvin, Olivier; Belleville, Sylvie; Ferland, Guylaine; Renaud, Mélanie; Bherer, Louis; Joubert, Sven; Vallet, Guillaume T; Simard, Martine; Rouleau, Isabelle; Lecomte, Sarah; Macoir, Joël; Hudon, Carol

    2015-01-01

    Performance on verbal memory tests is generally associated with socio-demographic variables such as age, sex, and education level. Performance also varies between different cultural groups. The present study aimed to establish normative data for the Rappel libre/Rappel indicé à 16 items (16-item Free and Cued Recall; RL/RI-16), a French adaptation of the Free and Cued Selective Reminding Test (Buschke, 1984; Grober, Buschke, Crystal, Bang, & Dresner, 1988). The sample consisted of 566 healthy French-speaking older adults (50-88 years old) from the province of Quebec, Canada. Normative data for the RL/RI-16 were derived from 80% of the total sample (normative sample) and cross-validated using the remaining participants (20%; validation sample). The effects of participants' age, sex, and education level were assessed on different indices of memory performance. Results indicated that these variables were independently associated with performance. Normative data are presented as regression equations with standard deviations (symmetric distributions) and percentiles (asymmetric distributions). PMID:24815338

  12. Ajuste de parámetros libres en teorías de campos camaleones a partir de espectros de nubes moleculares galácticas y experimentos terrestres

    NASA Astrophysics Data System (ADS)

    Teppa Pannia, F. A.; Landau, S. J.

    Resultados recientes, basados en el análisis de espectros moleculares de nubes galácticas a través del método del amoníaco, han arrojado nuevos límites sobre la variación del parámetro adimensional μ=m_e /m_p. Los resultados indican Δ μ/μ = (μ_{obs}-μ_{lab})/μ_{lab}= (2.2± 0.4_{est} ±0.3_{sist}) times 10 ^{-8}, en acuerdo con una variación no nula de dicha cantidad (Levshakov et al. 2010). En este trabajo, motivado por los datos astronómicos, estudiamos la solución lineal del modelo teórico fenomenológico de campo escalar camaleón, presentado por Mota y Shaw (2007), que predice variaciones en μ. Con el fin de cotejar estas predicciones con los resultados observacionales, utilizamos datos de experimentos terrestres que testean violaciones al Principio de Equivalencia para analizar el valor de los parámetros libres presentes en el modelo. El trabajo realizado muestra que la solución estudiada no se puede ajustar a los datos experimentales, sugiriendo que el modelo lineal debe ser descartado para explicar las observaciones astronómicas. FULL TEXT IN SPANISH

  13. Determinación de la orientación global SAO-Hipparcos mediante una expansión en armónicos vectoriales

    NASA Astrophysics Data System (ADS)

    Cionco, R. G.; Vucetich, H.; Orellana, R.; Arias, E. F.

    En base a las diferencias de posición y movimientos propios de 101352 estrellas con posición SAO observadas por HIPPARCOS y utilizando la naturaleza vectorial de esas diferencias, determinamos 6 parámetros de orientación global (3 de rotación y 3 de desplazamiento axial), para los sistemas de referencia asociados a los marcos mencionados, mediante una descomposición en serie de armónicos vectoriales ortogonales.

  14. Interprétation cohérente du coefficient de Poisson négatif rapporté dans des multicouches métalliques : rôle du paramètre libre de contrainte

    NASA Astrophysics Data System (ADS)

    Badawi, K. F.; Goudeau, Ph.; Durand, N.

    1998-04-01

    étermination expérimentale par la méthode des sin^2Psi de la référence (paramètre libre de contrainte) servant de base au calcul des déformations. Nous montrons alors que l'introduction du paramètre du matériau massif comme référence est une hypothèse irréaliste dans le cas des films minces et multicouches (W et Ag/Ni) qui peut conduire à des résultats erronés et en total désaccord avec ceux obtenus par d'autres techniques. Ainsi, l'anomalie élastique au niveau du coefficient de Poisson soulevée par certains auteurs dans la littérature n'est pas imputable à la structure elle-même mais à l'analyse qui est faite des données expérimentales obtenues par diffraction des rayons X.

  15. Numerical modeling of incline plate LiBr absorber

    NASA Astrophysics Data System (ADS)

    Karami, Shahram; Farhanieh, Bijan

    2011-03-01

    Among major components of LiBr-H2O absorption chillers is the absorber, which has a direct effect on the chillier size and whose characteristics have significant effects on the overall efficiency of absorption machines. In this article, heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water-cooled incline plate absorber in the Reynolds number range of 5 < Re < 150 is performed numerically. The boundary layer assumptions are used for the mass, momentum and energy transport equations and the fully implicit finite difference method is employed to solve the governing equations. Dependence of lithium bromide aqueous properties to the temperature and concentration is employed as well as dependence of film thickness to vapor absorption. An analysis for linear distribution of wall temperature condition carries out to investigate the reliability of the present numerical method through comparing with previous investigation. The effect of plate angle on heat and mass transfer parameters is investigated and the results show that absorption mass flux and heat and mass transfer coefficient increase as the angle of the plate increase. The main parameters of absorber design, namely Nusselt and Sherwood numbers, are correlated as a function of Reynolds Number and the plate angle.

  16. Actividades al Aire Libre (Outdoor Activities). OBIS/Mini-Corps.

    ERIC Educational Resources Information Center

    California Univ., Berkeley. Lawrence Hall of Science.

    The all-Spanish version of the Outdoor Biology Instructional Strategies (OBIS)/Mini-Corps Outdoor Activities set contains twenty education and recreational activities which provide a variety of outdoor biological experiences and incorporate language skills into outdoor education. Prepared especially for use by migrant children aged 10-15 in a…

  17. Actividades al Aire Libre (Outdoor Activities). OBIS/Mini-Corps.

    ERIC Educational Resources Information Center

    California Univ., Berkeley. Lawrence Hall of Science.

    Prepared specifically for use in one-week outdoor summer camp programs for migrant children aged 10-15, the twenty bilingual (Spanish and English) educational and recreational activities in the Outdoor Biology Instructional Strategies (OBIS)/Mini-Corps package have been revised to develop language skills as well as an awareness of the outdoor…

  18. Libre: Freeing Polar Data in an Information Commons

    NASA Astrophysics Data System (ADS)

    Duerr, R. E.; Parsons, M. A.

    2010-12-01

    As noted in the session description “The polar regions are at the forefront of modern environmental change, currently experiencing the largest and fastest changes in climate and environment”. Wise use of resources, astute management of our environment, improved decision support, and effective international cooperation on natural resource and geopolitical issues require a deeper understanding of, and an ability to predict change and its impact. Understanding and knowledge are built on data and information, yet polar information is scattered, scarce, and sporadic. Rapid change demands rapid data access. We envision a system where investigators quickly expose their data to the world and share them, without restriction, through open protocols on the Internet. A single giant, central archive is not practical for all polar data held around the world. Instead, we seek a collaborative, virtual space, where scientific data and information could be shared ethically and with minimal constraints. Inspired by the Antarctic Treaty of 1959 that established the Antarctic as a global commons to generate greater scientific understanding, the International Council of Science leads the Polar Information Commons (PIC). The PIC, engendered by the International Polar Year (IPY) and work on the IPY data policy, serves as an open, virtual repository for vital scientific data and information. An international network of scientific and data management organizations concerned with the scientific quality, integrity, and stewardship of data is developing the PIC. The PIC utilizes the Science Commons Protocol for Implementing Open Access Data, including establishment of community norms to encourage appropriate contributions to and use of PIC content. Data descriptions (metadata) are not necessarily registered in formal repositories or catalogues. They may simply be exposed to search engines or broadcast through syndication services such as RSS or Atom. The data are labeled or branded as part of the PIC and are, therefore, open for use without restriction. The PIC label also alerts data centers around the world to new polar data. These data centers then assess and acquire important data for formal archiving, curation, and access through national and global data systems. The intent is to enable rapid data access without qualification, while establishing a process for long-term preservation and stewardship of critical data. This paper will review the ethical and legal basis for sharing polar data and information, as well as the technologies being employed to make the PIC a reality.

  19. Educacion al Aire Libre: Libro de Actividades II = Outdoor Education: Student Activity Book II.

    ERIC Educational Resources Information Center

    Ada, Alma Flor, Comp.; And Others

    Divided into four sections, the book includes activities for students to do before camp, on the way to camp, at camp, and after camp. Activities to do before camp include writing proverbs, tongue twisters, riddles, poems, and stories. Activities to do on the way to camp include singing songs and reading a map. The words to the following songs are…

  20. Direct molecular diffusion and micro-mixing for rapid dewatering of LiBr solution

    SciTech Connect

    Bigham, S; Isfahani, RN; Moghaddam, S

    2014-03-01

    A slow molecular diffusion rate often limits the desorption process of an absorbate molecule from a liquid absorbent. To enhance the desorption rate, the absorbent is often boiled to increase the liquid vapor interfacial area. However, the growth of bubbles generated during the nucleate boiling process still remains mass-diffusion limited. Here, it is shown that a desorption rate higher than that of boiling can be achieved, if the vapor absorbent interface is continuously replenished with the absorbate-rich solution to limit the concentration boundary layer growth. The study is conducted in a LiBr-water-solution, in which the water molecules' diffusion rate is quite slow. The manipulation of the vapor solution interface concentration distribution is enabled by the mechanical confinement of the solution flow within microchannels, using a hydrophobic vapor-venting membrane and the implementation of microstructures on the flow channel's bottom wall. The microstructures stretch and fold the laminar streamlines within the solution film and produce vortices. The vortices continuously replace the concentrated solution at the vapor solution interface with the water-rich solution brought from the bottom and middle of the flow channel. The physics of the process is described using a combination of experimental and numerical studies. Published by Elsevier Ltd.

  1. A Case Study of an Induction Year Teacher's Problem-Solving Using the LIBRE Model Activity

    ERIC Educational Resources Information Center

    Guerra, Norma S.; Flores, Belinda Bustos; Claeys, Lorena

    2009-01-01

    Background: A federally-funded program at the University of Texas at San Antonio adopted a holistic problem solving mentoring approach for novice teachers participating in an accelerated teacher certification program. Aims/focus of discussion: To investigate a novice teacher's problem-solving activity through self-expression of challenges and…

  2. Design improvements in LiBr absorption chillers for solar applications

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Bourne, J. R.; Ben-Dror, J.; Kimchi, Y.; Vardi, I.

    1981-02-01

    The present article describes a theoretical evaluation of two design improvements made in a lithium bromide absorption chiller which contribute substantially to its performance in solar application. One is the addition of a solution preheater which allows for a considerable reduction in generator size and cost, and improves performance at part load. The other is the addition of an auxiliary generator which enables the chiller to operate at nominal capacity or higher at all times, while utilizing to a maximum the solar radiation available at the time, however small. This is an effective solution to the problem of backup required in all solar-powered systems. The evaluation has been performed by computer simulation and results are presented for the performance of the unit with different configurations of the above systems. The results indicate the limitations on the part of the load to be supplied by the preheater. They point toward the advantage of using an auxiliary generator in a separate shell from the solar-powered generator and with a separate condenser. Operating curves for the chiller with the design improvements are given.

  3. "Lucha Libre" and Cultural Icons: Identity Formation for Student Success at HSIs

    ERIC Educational Resources Information Center

    Natividad, Nicholas D.

    2015-01-01

    This chapter examines the importance of culturally relevant imagery and representation and identity development curriculum for college students. It calls for higher education institutions to embrace cultural strengths as an asset rather than a deficit.

  4. Meningococco B: controllo di due focolai epidemici mediante vaccinazione

    PubMed Central

    2014-01-01

    Riassunto La problematica di un efficace approccio vaccinale nei confronti del Meningococco B (MenB) è stata superata identificando con la metodica della "reverse vaccinology" alcuni antigeni capaci di indurre una risposta verso la maggior parte dei ceppi di MenB circolanti nel mondo. Il nuovo vaccino MenB a 4 componenti (4CMenB) è stato autorizzato in Europa, Australia e Canada, ed è entrato nei calendari di immunizzazione pediatrica internazionali: Australia, Canada, UK. In Italia, le prime regioni che hanno raccomandato la vaccinazione contro il MenB sono state Basilicata e Puglia. La gestione di epidemie/focolai epidemici richiede la messa in atto di una risposta rapida da parte delle autorità sanitarie nei confronti di una emergenza sanitaria ad elevato impatto, anche emotivo, sulla popolazione, come recentemente dimostrato in due università americane. Alla dichiarazione di focolaio epidemico in atto, in entrambi i contesti si è attivata una procedura per l'uso del vaccino 4CMenB non ancora autorizzato negli USA. È stato così possibile organizzare gli interventi di profilassi attiva nei due campus universitari, adottando il primo impiego su larga scala del nuovo vaccino 4CMenB e conseguendo, in tempi relativamente brevi, elevati tassi di copertura vaccinale. A fronte di circa 14000 studenti immunizzati con almeno una dose, non è stata segnalata alcuna problematica di eventi avversi conseguenti all'immunizzazione; ad oggi non si sono verificati casi nei soggetti che hanno ricevuto il vaccino. Come conseguenza dei due focolai descritti, è oggi in corso la valutazione da parte dell'FDA per l'estensione dell'uso del vaccino 4CMenB negli Stati Uniti negli adolescenti e giovani adulti. PMID:25916017

  5. Traduccion automatica mediante el ordenador (Automatic Translation Using a Computer).

    ERIC Educational Resources Information Center

    Bueno, Julian L.

    This report on machine translation contains a brief history of the field; a description of the processes involved; a discussion of systems currently in use, including three software packages on the market (Teaching Assistant, Translate, and Globalink); reflections on implications for teaching; observations of results obtained when elements of…

  6. Problem Identification and Task Engagement Using the LIBRE Problem Solving Tool: A Case Study of Three Bilingual Teacher Candidates

    ERIC Educational Resources Information Center

    Guerra, Norma; Castro-Villarreal, Felicia; Cheatham, Nicholas; Claeys, Lorena

    2014-01-01

    Bilingual Latino students engage multiple languages, cultures and environments as they pursue educational and professional goals. For this underrepresented group, pursuing a post-secondary degree is a "lucha" (fight) to negotiate the complex interplay of historical, educational, and cultural variables and achieve academic success.…

  7. Measured performance of a 3-ton LiBr absorption water chiller and its effect on cooling system operation

    NASA Technical Reports Server (NTRS)

    Namkoong, D.

    1976-01-01

    A 3-ton lithium bromide absorption water chiller was tested for a number of conditions involving hot-water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It is concluded that a 3-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  8. What Are They Learning? Pre-and Post-Assessment Surveys for LIBR 1100, Introduction to Library Research

    ERIC Educational Resources Information Center

    Hufford, Jon R.

    2010-01-01

    Articles reporting the experiences of librarians in assessing what students are learning in information literacy classes are as of yet not as well represented in the professional literature as they should be. This is especially the case for library skills courses that are for-credit. Librarians who have experience assessing student learning should…

  9. Measured performance of a 3 ton LiBr absorption water chiller and its effect on cooling system operation

    NASA Technical Reports Server (NTRS)

    Namkoong, D.

    1976-01-01

    A three ton lithium bromide absorption water chiller was tested for a number of conditions involving hot water input, chilled water, and the cooling water. The primary influences on chiller capacity were the hot water inlet temperature and the cooling water inlet temperature. One combination of these two parameters extended the output to as much as 125% of design capacity, but no combination could lower the capacity to below 60% of design. A cooling system was conceptually designed so that it could provide several modes of operation. Such flexibility is needed for any solar cooling system to be able to accommodate the varying solar energy collection and the varying building demand. It was concluded that a three-ton absorption water chiller with the kind of performance that was measured can be incorporated into a cooling system such as that proposed, to provide efficient cooling over the specified ranges of operating conditions.

  10. IT Policies for Development: Analysis and Recommendations of Free Libre Open Source Software Initiatives of the Bolivarian Republic of Venezuela

    ERIC Educational Resources Information Center

    Maldonado Rangel, Edgar A.

    2009-01-01

    In recent years the two concepts of economic development and technological advancement have become entwined so that they have, in many cases, come to mean the same thing. For countries seeking economic development through engagement with the Information Economy, policies supporting technological development claim privileged positions in national…

  11. Extension de la méthode de Kármán-Pohlhausen aux régimes transitoires de convection libre, pour Pr>0,6

    NASA Astrophysics Data System (ADS)

    Polidori, Guillaume; Mladin, Emilia-Cerna; de Lorenzo, Thierry

    This work is devoted to the unsteady free laminar convection theory applied to a heated isoflux vertical plate by using the integral Kármán-Pohlhausen approach. To overcome complexities due to transient integral method, the analysis assumes that the ratio of both velocity and temperature layers is only Prandtl number dependent during the transient phase. Comparisons with results from the differential method seem to validate the proposed modeling which is carried out for the range Pr>0.6.

  12. Listen-Identify-Brainstorm-Reality-Test-Encourage (LIBRE) Problem-Solving Model: Addressing Special Education Teacher Attrition through a Cognitive-Behavioral Approach to Teacher Induction

    ERIC Educational Resources Information Center

    Guerra, Norma S.; Hernandez, Art; Hector, Alison M.; Crosby, Shane

    2015-01-01

    Special education teacher attrition rates continue to challenge the profession. A cognitive-behavioral problem-solving approach was used to examine three alternative certification program special education teachers' professional development through a series of 41 interviews conducted over a 2-year period. Beginning when they were novice special…

  13. Roads to Success in the Belgian French Community's Higher Education System: Predictors of Dropout and Degree Completion at the Université Libre De Bruxelles

    ERIC Educational Resources Information Center

    Arias Ortiz, Elena; Dehon, Catherine

    2013-01-01

    In this paper we study the factors that influence both dropout and (4-year) degree completion throughout university by applying the set of discrete-time methods for competing risks in event history analysis, as described in Scott and Kennedy (2005). In the French-speaking Belgian community, participation rates are very high given that higher…

  14. Tips for Parents on Keeping Children Drug Free = Consejos para Los Padres Sobre Como Mantener a Los Hijos Libres de La Droga.

    ERIC Educational Resources Information Center

    Department of Education, Washington, DC. Office of Intergovernmental and Interagency Affairs.

    Research shows that recent trends in youth drug use have stabilized; however, the rates of use remain at high levels. It has been shown that the earlier drug use is initiated, the more likely a person is to develop drug problems later in life. Youth substance abuse may lead to many other problems that affect not only the child, but also the…

  15. Representations of Cooperative Interactions and Their Development in Preschoolers (Representation des composantes de la cooperation au prescolaire dans des situations ludiques libres).

    ERIC Educational Resources Information Center

    Garnier, Catherine

    Six groups of children 2- to 4-years-old were videotaped and interviewed during five 30-minute free play sessions for the purpose of investigating the evolution of children's conceptions of the process of cooperation. Children's answers were organized into six themes, each of which described some aspect of cooperative activity. For each theme,…

  16. Analyse spectroscopique d'etoiles naines blanches riches en hydrogene (DA): vers des modeles d'atmosphere ameliores sans parametres libres

    NASA Astrophysics Data System (ADS)

    Tremblay, Pier-Emmanuel

    2011-01-01

    The goal of this thesis is to refine and to understand better the spectroscopic method, which compares optical spectra of hydrogen-atmosphere white dwarfs (DA) with synthetic spectra to determine the atmospheric parameters (effective temperature and surface gravity). Our approach rests mainly on the development of improved model spectra, which come themselves from DA model atmospheres. We present a new grid of DA synthetic spectra with the first consistent implementation of the non-ideal gas theory of Hummer & Mihalas and the unified theory of Stark broadening from Vidal, Cooper & Smith. This allows for an adequate treatment of the quenching effects in Balmer lines, without the need of a free parameter. We show that these improved spectra predict surface gravities that are much more stable as a function of the effective temperature. We then study the long-standing problem that surface gravities in cool DA stars are significantly higher than those found in hotter DA white dwarfs. The hypothesis of Bergeron et al., according to which the atmospheres are contaminated by small amounts of helium, is constrained with observations. Using high-resolution spectra collected at the Keck in Hawaii, we find superior limits on the helium abundances in the atmospheres that are nearly 10 times lower than those required to sustain the Bergeron et al. scenario. The grid of spectra calculated in this work is then applied to a new spectroscopic analysis of the DA in the SDSS. Our careful analysis allows us to define a cleaner sample and to identify a large number of double degenerates. We find that a cutoff at a signal-to-noise ratio ≳ 15 optimizes the size and quality of the sample for computing the average mass, for which we find a value of 0.613 M⊙ . Finally, eight new 3D white dwarf models with a radiative-hydrodynamics treatment of the convection are presented. We also calculated models with the same physics, except for a treatment of the convection with the standard mixing-length theory. A differential analysis between these two sets of models shows that the 3D models predict considerably lower surface gravities. We conclude that the high-log g problem in cool DA white dwarfs is caused by a weakness in the mixing-length theory. Subject headings: stars: atmospheres --- stars: structure and evolution --- white dwarfs --- line profiles --- convection

  17. Mejora de la escuela mediante informacion (Data-Driven School Improvement). ERIC Digest.

    ERIC Educational Resources Information Center

    Johnson, James H.

    With accurate information, educators are better able to make effective decisions. Besides being used to assess student performance, a complete program of data collection and use can also show educators how management skills, individual learning styles, and other elements affect student achievement. This digest in Spanish provides an overview of…

  18. Determinacion de periodos fundamentales del suelo mediante vibraciones ambientales en el municipio de Humacao, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Cintron Aponte, Rommel

    La tecnica de Nakamura ha sido utilizada a nivel mundial para determinar periodos fundamentales del suelo. La tecnica consiste en calcular y graficar cocientes espectrales H/V de vibraciones ambientales registradas sobre el suelo. Mediciones de vibraciones ambientales fueron tomadas en 151 lugares dentro del municipio de Humacao, localizado al este de Puerto Rico. Los datos se procesaron utilizando espectros de Fourier y espectros de potencia. La tecnica fue validada al compararla con los resultados de cocientes espectrales H/V de registros de sismos debiles y tambien con una modelacion numerica realizada con datos de un ensayo "downhole". Las graficas de los cocientes espectrales H/V fueron divididas en casos y grupos, los cuales dependen de la facilidad para identificar el periodo fundamental pico y amplitudes en frecuencias menores de 1 Hz, respectivamente. Los resultados obtenidos con ambos espectros fueron comparados y se concluye que los mismos se complementan para proveer resultados mas confiables. Se crearon mapas de periodos fundamentales, factores de amplitud, isoperiodos y clasificacion sismica de sitio. Los mapas de isoperiodos fueron realizados en las zonas mas pobladas sobre depositos de suelo. El mapa de periodos fundamentales del suelo mostro buena correlacion con la geologia local. El mapa de clasificacion sismica derivado de periodos de sitio fue comparado con el mapa de clasificacion sismica derivado de barrenos geotecnicos. El mapa de clasificacion obtenido de periodos puede sobreestimar un poco algunas clasificaciones del suelo. Sin embargo, este mapa puede proveer un estimado aproximado de la velocidad de onda de corte promedio del suelo hasta una profundidad de 100 pies (30 metros).

  19. The Investigation of Mass Transfer in the Karasu Karstic Aquifer, Konya, Turkey

    NASA Astrophysics Data System (ADS)

    Ozdemir, Adnan; Nalbantcilar, Tahir

    2002-09-01

    In this study, the changes in the chemical composition of the groundwater along a flow path were examined by using the water samples collected from unconfined, semi-confined and confined parts of the Karasu karstic aquifer. It was determined that transport of bicarbonate, calcium, and magnesium was dominant in unconfined and semi-confined parts of the aquifer, whereas calcite and dolomite precipitate in the confined parts. On the other hand, gypsum dissolution is present in all parts of the aquifer. In addition, the computed saturation indices explain the occurrences and precipitation of travertines in the Goksu Valley, which is the discharge area for the aquifer. Résumé. Les modifications de la composition chimique de l'eau souterraine le long d'un axe d'écoulement ont été étudiées à partir d'échantillons prélevés dans les parties libres, semi-captives et captives de l'aquifère karstique de Karasu. On a mis en évidence que le transport de carbonate, de calcium et de magnésium est prépondérant dans les parties libres et semi-captives de l'aquifère, alors que la calcite et la dolomite précipitent dans les parties captives. En outre, la dissolution du gypse se produit dans toutes les parties de l'aquifère. Par ailleurs, les indices de saturation calculés rendent compte de l'existence et de la précipitation des travertins dans la vallée du Göksu, qui est la zone de décharge de cet aquifère. Resumen. En este estudio, se han examinado los cambios de composición química en las aguas subterráneas a lo largo de una línea de corriente mediante el análisis de muestras recogidas en partes libres, semiconfinadas y cautivas del acuífero cárstico de Karasu. Se ha determinado que el transporte de bicarbonato, calcio y magnesio es dominante en las zonas libres y semiconfinadas, mientras que la calcita y la dolomita precipitan en las zonas confinadas. Por otro lado, la disolución de yesos ocurre en todo el ámbito del acuífero. Además, los

  20. Neurobiología del autismo y TDAH mediante técnicas de neuroimagen: divergencias y convergencias

    PubMed Central

    Proal, Erika; Olvera, Jorge González; Blancas, Aurea S.; Chalita, Pablo J.; Castellanos, F. Xavier

    2013-01-01

    En el área clínica algunos síntomas del trastorno por déficit de atención e hiperactividad (TDAH), se presentan en los pacientes con trastorno del espectro autista (TEA). Se ha demostrado que existen alteraciones en circuitos cerebrales que impactan en fallas cognitivas y de comportamiento específicas de cada uno de estos trastornos. Sin embargo, han sido poco estudiados los correlatos cerebrales que hay detrás tanto de las similitudes como de las diferencias sintomatológicas. En la presente revisión se analizaron los estudios meta-analíticos existentes estructurales y funcionales en TDAH y TEA. Por un lado, se observaron convergencias en circuitos como el dorsal atencional, de funciones ejecutivas, visual, somatomotor y circuito de activación por defecto. Estas similitudes posiblemente explican las manifestaciones comórbidas entre los trastornos como la falla en la integración de información, motricidad fina y procesos atencionales específicos. Por otro lado, específicamente en el TDAH se observan déficits en el circuito de recompensa y ventral atencional, sistemas involucrados en la medición de efectos de reforzamiento y monitoreo atencional. En TEA los circuitos más afectados fueron los implicados en procesos de cognición social y lenguaje. En conclusión, existen correlatos neuronales en TEA que explican las manifestaciones clínicas tanto convergentes como divergentes presentes en TDAH. PMID:23897144

  1. Una prueba empírica de generadores de nümeros pseudoaleatorios mediante un proceso de decaimiento exponencial

    NASA Astrophysics Data System (ADS)

    Coronel-Brizio, H. F.; Hernández-Montoya, A. R.; Jiménez-Montaño, M. A.; Mora-Forsbach, L. E.

    2007-10-01

    Empirical tests for pseudorandom number generators based on the use of processes or physical models have been successfuly used and are considered as complementary to theoretical test of randomness. In this work a statistical methodology for evaluating the quality of pseudorandom number generators is presented. The method is illustrated in the context of the so-called exponential decay process, using some pseudorandom number generators commonly used in physics.

  2. IDEA: Ensenanza de romances espanoles mediante la musica y el arte (IDEA: Teaching Spanish "Romances" Through Music and Art).

    ERIC Educational Resources Information Center

    Garcia Glick, Beatriz

    1999-01-01

    Terrell's natural approach suggests that such interactive activities as music and art induce and improve student communication in language learning. Explanation of the method's steps uses the poem "Abenamar" as an example. The teacher first presents the work in historical context, then reads the work accompanied by visual aids, then reads to music…

  3. Cálculo del esfuerzo ideal de metales nobles mediante primeros principios en la dirección <100>

    NASA Astrophysics Data System (ADS)

    Bautista-Hernández, A.; López-Fuentes, M.; Pacheco-Espejel, V.; Rivas-Silva, J. F.

    2005-04-01

    We present calculations of the ideal strength on the < 100 > direction for noble metals (Cu, Ag and Au), by means of first principles calculations. First, we obtain the structural parameters (cell parameters, bulk modulus) for each studied metal. We deform on the < 100 > direction calculating the total energy and the stress tensor through the Hellman-Feynman theorem, by the relaxation of the unit cell in the perpendicular directions to the deformation one. The calculated cell constants differ 1.3 % from experimental data. The maximum ideal strength are 29.6, 17 and 19 GPa for Cu, Ag and Au respectively. Meanwhile, the calculated elastic modulus are 106 (Cu), 71 (Ag), and 45 GPa (Au) and are in agreement with the experimental values for polycrystalline samples. The values of maximum strength are explained by the optimum volume values due to the atomic radius size for each element.

  4. [A comparison of the performances between healthy older adults and persons with Alzheimer's disease on the Rey auditory verbal learning test and the Test de rappel libre/rappel indicé 16 items].

    PubMed

    Drolet, Valérie; Vallet, Guillaume T; Imbeault, Hélène; Lecomte, Sarah; Limoges, Frédérique; Joubert, Sven; Rouleau, Isabelle

    2014-06-01

    The aim of this research was to compare the performances of healthy elderly (n=40) and individuals with Alzheimer's disease (AD, n=40) on the RL/RI 16, a French adaptation of the Free and cued selective reminding test (FCSRT) and on the Rey auditory verbal learning test (RAVLT). These two verbal episodic memory tests are frequently used in clinical practice in French-speaking populations. Results showed that the RAVLT demonstrated a slightly better sensitivity and sensibility than the RL/RI 16. The RAVLT allowed to classify participants of the two groups without any overlap. Moreover, no floor effect was observed in the RAVLT in AD and ceiling effects were less pronounced in normal controls that in the RL/RI 16. Results observed in the RL/RI 16 showed important ceiling effects and a decline in performance on free recall throughout trials in AD patients. Nonetheless, the latter tool was less sensitive to recency effects than the RAVLT and may thus provide a more realistic view of the long-term memory performance of these patients. The semantic cues provided in the RL/RI 16 appeared to increase intrusions in AD whereas the interference list in the RAVLT was the first source of false recognitions in both healthy elderly and AD. In conclusion, this paper demonstrates both the advantages and disadvantages of these two tools in the evaluation of episodic memory in elderly with and without cognitive deficits. PMID:24939409

  5. Modelo Pedagogico de Educacion Primaria para Adultos: Manual para el Asesor de Estudiantes Libres. Primera Parte (A Pedagogical Model for Adult Primary Education: Manual for the Student Advisor. Part One).

    ERIC Educational Resources Information Center

    Instituto Nacional para la Educacion de los Adultos, Mexico City (Mexico).

    This guide, part of a Mexican series of instructional materials, is intended for advisors of students participating in an adult education program offered through public and private organizations in communities in Mexico. The first part of the program comprises Spanish and math; the second, education for family life, education for community life,…

  6. Effects of radiation on carbapenems

    NASA Astrophysics Data System (ADS)

    Tepe, Semra; Polat, Mustafa; Korkmaz, Mustafa

    In the present work, effects of gamma radiation on solid meropenem trihydrate (MPT), which is the active ingredient of carbapenem antibiotics, were investigated by electron spin resonance (ESR) spectroscopy. Irradiated MPT presents an ESR spectrum consisting of many resonance peaks. Heights measured with respect to the spectrum baseline of these resonance peaks were used to explore the evolutions of the radicalic species responsible for the experimental spectrum under different conditions. Variations of the denoted 11 peak heights with microwave power, sample temperature and applied radiation doses and decay of the involved radicalic species at room and at high temperatures were studied. On the basis of the results derived from these studies, a molecular model consisting of the presence of four different radicalic species was proposed, and spectroscopic parameters of these species were calculated through spectrum simulation calculations. The dosimetric potential of MPT was also explored and it was concluded that MPT presents the characteristics of normal and accidental dosimetric materials.

  7. Can a Pb/SCIFI calorimeter survive the SSC

    SciTech Connect

    Hertzog, D.W.; Hughes, S.A.; Reimer, P.E.; Tayloe, R.L. ); Johnson, K.F. ); Majewski, S.; Zorn, C.; Zorn, M. )

    1990-01-01

    A scintillating fiber based electromagnetic calorimeter module built from radiation-hard materials has been tested in a beam capable of delivering both low and high currents of monoenergetic electrons. Energy resolution and light output measurements were made following high-dose exposures. The procedure was repeated until the resolution of the detector decreased from an initial value of 6.9%{radical}E to 14.0%{radical}E and the pulse height dropped by a factor of 11. After four weeks, the detector was retested. Partial recovery was observed in the light output which returned to approximately 52% of its original value. The resolution recovered to a value of 8.8%{radical}E. The tests are described. 9 refs., 4 figs.

  8. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    NASA Astrophysics Data System (ADS)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both

  9. Experiencias, Sentido y Significado de la Consejeria en Justicia Social a Nivel Universitario: Estudio de Caso Cualitativo Mediante Tres Narrativas De Consejeros Profesionales en Educacion Superior

    ERIC Educational Resources Information Center

    Santiago Tosado, Virginia

    2012-01-01

    The purpose of the study was to understand and profoundly describe the nature of social justice practice, as is comes up from the experience of three professional counselors whose working settings are the academic arena. Detailed descriptions are presented concerning the meanings and sense of counseling for social justice, as the interviews…

  10. Desarrollo de la Escala sobre el Estigma Relacionado con el VIH/SIDA para Profesionales de la Salud mediante el uso de métodos mixtos123

    PubMed Central

    Varas-Díaz, Nelson; Neilands, Torsten B.; Guilamo-Ramos, Vincent; Cintrón Bou, Francheska N.

    2009-01-01

    El estigma relacionado con el VIH/SIDA continúa siendo un obstáculo para la prevención primaria y secundaria del VIH. Las consecuencias para las personas que viven con la enfermedad han sido muy documentadas y continúan siendo una gran preocupación para las personas que proveen servicios de salud y para aquellas que investigan el tema. Estas consecuencias son preocupantes cuando el estigma emana de profesionales de la salud porque se puede limitar el acceso a los servicios. Uno de los principales obstáculos para la investigación del estigma relacionado con el VIH en Puerto Rico es la falta de instrumentos cuantitativos para evaluar las manifestaciones del estigma entre profesionales de la salud. El objetivo principal de este estudio fue desarrollar y probar las propiedades psicométricas de una escala sobre el estigma relacionado con el VIH/SIDA culturalmente apropiada para personas que proveen servicios de salud puertorriqueñas y desarrollar una versión corta de la escala que pudiera usarse en escenarios clínicos con tiempo limitado. El instrumento desarrollado estuvo basado en evidencia cualitativa recopilada entre profesionales y estudiantes de profesiones de la salud puertorriqueños/as (n=80) y administrado a una muestra de 421 profesionales de la salud en adiestramiento. La escala contenía 12 dimensiones del estigma relacionado con el VIH/SIDA. El análisis cuantitativo corroboró 11 de ellas, teniendo como resultado un instrumento con validez y confiabilidad satisfactoria. Estas dimensiones, a su vez, fueron subcomponentes de un factor de estigma general superior. PMID:20333258

  11. Ajuste de espectros integrados de cúmulos estelares de la Nube Mayor de Magallanes mediante el código Starlight

    NASA Astrophysics Data System (ADS)

    Minniti, J. H.; Vega, L. R.; Ahumada, A. V.; Clariá, J. J.

    2015-08-01

    The fit of synthetic spectra has proved to be a powerful tool for determining astrophysical parameters of stellar clusters (SCs). Such methodology is particularly useful to treat integrated spectra of extragalactic SCs. In this work, we present the results obtained by applying this technique to a sample of SCs belonging to the Large Magellanic Cloud (LMC) observed from CASLEO, and using the starlight code. The fitting of the data was performed by means of evolutive--synthesis models of simple--stellar populations of different ages and metallicities, based on the MILESM stellar libraries. The integrated spectra of 34 SCs of the LMC were fitted in order to obtain the age and metallicity of each object. This study also presents a comparison between the properties derived from those fittings and the method of confrontation of our observations with spectral templates of well known ages.

  12. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    NASA Astrophysics Data System (ADS)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both methods of identification, it is possible to distinguish between valid observations and observational artifacts. Furthermore, the method allows for the selection of objects of interest for follow-up observations, in order to determine their nature.

  13. Captura de amonio procedente de estiercol mediante membranas permeables de gases (capture of ammonnia from turkey manure using gas-permeable membranes)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper, written in Spanish, describes the capture and recovery of gaseous ammonia from turkey manure using gas-permeable membranes technology with formation of stabilized ammonium salts. Bench experiments were carried out in Maryland using a pilot prototype system with turkey litter inside contr...

  14. Calibración del retardo ionosférico en observaciones astrométricas y geodésicas a partir de observaciones GPS

    NASA Astrophysics Data System (ADS)

    Brunini, C.; Kleusberg, A.; Arias, E. F.; de Biasi, M. S.

    Los parámetros astrométricos y geodésicos de precisión se determinan hoy mediante la observación con técnicas espaciales (VLBI, GPS y LSR). Las técnicas VLBI y GPS operan en la banda de microondas y en ella la ionósfera terrestre es dispersiva. Las señales que provienen de las radiofuentes y de los satélites atraviesan la ionósfera, donde el índice de refracción difiere de la unidad en una cantidad que es proporcional a la densidad de electrones libres e inversamente proporcional al cuadrado de la frecuencia de la onda portadora. Actualmente el International GPS Service for Geodynamics (IGS) mantiene operacional una red global integrada por más de 50 estaciones equipadas con receptores GPS de alta performance; las observaciones diarias son accesibles a los usuarios mediante ftp. La posibilidad de utilizar estas observaciones en un monitoreo continuo de la ionósfera fue señalada por diversos autores, razón por la cual en los últimos años se ha invertido un significativo esfuerzo en la producción de mapas ionosféricos regionales y globales. En el presente trabajo se utilizan 28 estaciones cuyas observaciones mapean la mayor parte de la ionósfera global. Los resultados obtenidos demuestran la posibilidad de obtener mapas ionosféricos globales con una resolución de medio día y con una precisión de (1.5 nseg (rms)). Dichos mapas proveen valores medios globales para el intervalo ajustado. Los residuos del ajuste por mínimos cuadrados constituyen una señal a partir de la cual pueden estudiarse mejor las variaciones geográficas de la ionósfera y las componentes estadísticas de su variación temporal.

  15. Surface Tension Characteristics of Aqueous Lithium Bromide Solution with Alcoholic Surfactant

    NASA Astrophysics Data System (ADS)

    Sasaki, Naoe; Ogawa, Kiyoshi

    At present, the combination of aqueous lithium bromide (LiBr) solution as an absorbent and water as a refrigerant have widely been used as the working fluid for absorption refrigerating machines. In order to obtain absorption enhancement of water vapor into the LiBr solution by Marangoni convection, an alcoholic surfactant is being added in the LiBr solution. In that case, the surface tension of the LiBr solution with the surfactant plays an important role for the vapor absorption. In this study, the surface tensions of the LiBr solution with several alcoholic surfactants such as 1-butanol, 1-hexanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 1-heptanol, 1-octanol and 2-ethyl-1-hexanol were measured by Wilhelmy plate method. As a result, the surface tensions of 50 wt% LiBr solution with several surfactants were obtained over the LiBr solution temperature range from 298 K to 318 K and the surfactant concentration range from 0 to 104 ppm by mass. The measured surface tension has decreased with the increasing number of carbons included in the surfactant at constant concentration, and the surface tension has increased with the increasing temperature of 50 wt% LiBr solution. The surface tension increase of 1-octanol became greater than any other surfactant used in this work. The effective carbon number of the surfactant for the absorption enhancement was in the range from 7 to 8.

  16. Electromagnetic and hadron calorimeters in the MIPP experiment

    SciTech Connect

    Nigmanov, T.S.; Gustafson, H.R.; Longo, M.J.; Park, H.K.; Rajaram, D.; Dukes, C.; Lu, L.C.; Materniak, C.; Nelson, K.; Norman, A.; Meyer, H.; /Fermilab /Harvard U. /Indiana U. /Iowa U. /Purdue U.

    2008-10-01

    The purpose of the MIPP experiment is to study the inclusive production of photons, pions, kaons, and nucleons in {pi}, K, and p interactions on various targets using beams from the Main Injector at Fermilab. The function of the calorimeters is to measure the production of forward-going neutrons and photons. The electromagnetic calorimeter consists of 10 lead plates interspersed with proportional chambers. It was followed by the hadron calorimeter with 64 steel plates interspersed with scintillator. The data presented were collected with a variety of targets and beam momenta from 5 to 120 GeV/c. The energy calibration of both calorimeters with electrons, pions, kaons, and protons is discussed. The resolution for electrons was found to be 0.27/{radical}E, and for hadrons the resolution was 0.554/{radical}E with a constant term of 2.6%. The performance of the calorimeters was tested on a neutron sample.

  17. Encouraging Teenagers to Improve Speaking Skills through Games in a Colombian Public School (Motivación de adolescentes para mejorar su expresión oral mediante el juego en un colegio público colombiano)

    ERIC Educational Resources Information Center

    León, William Urrutia; Cely, Esperanza Vega

    2010-01-01

    Our project was implemented with tenth grade students of a public school located in the Usme Zone in Bogotá. We decided to develop this action research project because we were concerned about our students' difficulties when attempting to speak English. They felt inhibited with activities that involved oral interaction mainly because they were…

  18. Fostering Intercultural Communicative Competence through Reading Authentic Literary Texts in an Advanced Colombian EFL Classroom: A Constructivist Perspective (Desarrollo de la competencia comunicativa intercultural mediante la lectura de textos literarios auténticos: una perspectiva constructivista)

    ERIC Educational Resources Information Center

    Gómez, Luis Fernando R.

    2012-01-01

    This article describes an action research experience carried out in an advanced English as a foreign language classroom of the language program at a university in Bogotá, Colombia, in 2010. The study proposes the inclusion of authentic literary texts in the English as a foreign language classroom through the implementation of four constructivist…

  19. "La Evaluacion de la Actuacion Oral de los Hispanoparlantes Bilingues Mediante las Directrices de ACTFL (Evaluation of the Oral Presentation of the Bilingual Spanish Speaking Professionals by Moderators of the ACTFL).

    ERIC Educational Resources Information Center

    Alonso, Esther

    1997-01-01

    Discusses the validity of a rating scale created by the American Council on the Teaching of Foreign Languages for the purpose of measuring the oral language proficiency of bilingual professionals who are speakers of English and Spanish. Notes that this scale measures various levels of competence and features of an individual's speech. (14…

  20. Self-Access Language Learning: Students' Perceptions of and Experiences within This New Mode of Learning (Aprendizaje de idiomas mediante la modalidad de autoacceso: percepciones y experiencias de los estudiantes)

    ERIC Educational Resources Information Center

    Herrera Díaz, Luz Edith

    2012-01-01

    With the aim of fostering autonomy in learning, both innovations, the self-access centre and the mode of learning derived from it, were adopted in the context of the study (Language Centre in the University of Veracruz, Mexico). Based on a case study, I have adopted a qualitative perspective to do this research, which aimed to know how the…

  1. El rol de Ia colaboracion y el Modelo de Aprendizaje Basado en Proyectos (ABPr) mediante el lente de la Teoria de Actividad (CHAT): un estudio de caso con estudiantes de 9no grado

    NASA Astrophysics Data System (ADS)

    Delgado, Isabel C.

    Los modelos de eensenanza y aprendizaje constructivistas conceptualizan el aprendizaje como un proceso activo. El modelo de Aprendizaje Basado en Proyectos (ABPr) se distingue por una serie de componentes, entre los cuales se destaca el aspecto colaborativo y cooperativo como un reto al momento de su implantacion. Son pocas las investigaciones que se concentran en este aspecto del modelo. En este estudio, se analizaron las diversas interacciones que surgen durante la implantacion de una unidad curricular sobre el tema de Geologia de Puerto Rico, la cual se diseno con el modelo ABPr cuyo enfoque es orientacion a proyectos. Particularmente, se examinaron las interacciones sociales que surgen entre los pares y entre pares y docente durante el proceso de planificacion y desarrollo de los productos finales, al igual que las interacciones entre los estudiantes y el material didactico en estas etapas del modelo. La investigacion es de tipo cualitativo e incorpora como diseno el estudio de caso. Las diversas interacciones constituyen la unidad de analisis. En el estudio participaron 19 estudiantes de 9no grado, a quienes se organizaron en 5 grupos colaborativos por temas de interes (Pangea, Placas tectonicas, Volcanes, Tsunamis y Terremotos). Las tecnicas que se utilizaron para recopilar los datos fueron: observaciones participativas, grupos focales y analisis de documentos (cuadernos reflexivos y respuestas de los estudiantes a la pregunta central del proyecto). Para el analisis de los datos se aplico la teoria de actividad (CHAT) que concentra la unidad de analisis en la actividad humana en un contexto particular. Los resultados del estudio senalan que las interacciones entre pares, entre pares y docente, asi como entre estudiantes y material didactico son fundamentales en el proceso de aprendizaje. Una mayor interaccion entre pares durante las etapas de planificar y desarrollar los productos finales de la unidad, promueve una mejor comprension de los conceptos de la unidad, segun evidencia los productos finales del ABPr. La interaccion con el docente es muy importante para mediar los conflictos y desacuerdos que surgen como parte de las interacciones entre pares. Por lo tanto, el uso de diversas estrategias de andamiaje por parte del docente durante las reuniones de los grupos colaborativos es esencial para el exito del modelo ABPr.

  2. The Impact of Conferencing Assessment on EFL Students' Grammar Learning (Impacto de la evaluación mediante conferencias en el aprendizaje de la gramática en estudiantes de inglés como lengua extranjera)

    ERIC Educational Resources Information Center

    Baleghizadeh, Sasan; Zarghami, Zahra

    2012-01-01

    This article reports on a study that was carried out in order to examine the impact of conferencing assessment on students' learning of English grammar. Forty-two Iranian intermediate university students were randomly assigned to an experimental and a control group. The participants in the experimental group took part in four individual and…

  3. Planificación Neuroquirúrgica con Software Osirix

    PubMed Central

    Jaimovich, Sebastián Gastón; Guevara, Martin; Pampin, Sergio; Jaimovich, Roberto; Gardella, Javier Luis

    2014-01-01

    Introducción: La individualidad anatómica es clave para reducir el trauma quirúrgico y obtener un mejor resultado. Actualmente, el avance en las neuroimágenes ha permitido objetivar esa individualidad anatómica, permitiendo planificar la intervención quirúrgica. Con este objetivo, presentamos nuestra experiencia con el software Osirix. Descripción de la técnica: Se presentan 3 casos ejemplificadores de 40 realizados. Caso 1: Paciente con meningioma de la convexidad parasagital izquierda en área premotora; Caso 2: Paciente con macroadenoma hipofisario, operada previamente por vía transeptoesfenoidal en otra institución con una resección parcial; Caso 3: Paciente con lesiones en pedúnculo cerebeloso medio bilateral. Se realizó la planificación prequirúrgica con el software OsiriX, fusionando y reconstruyendo en 3D las imágenes de TC e IRM, para analizar relaciones anatómicas, medir distancias, coordenadas y trayectorias, entre otras funciones. Discusión: El software OsiriX de acceso libre y gratuito permite al cirujano, mediante la fusión y reconstrucción en 3D de imágenes, analizar la anatomía individual del paciente y planificar de forma rápida, simple, segura y económica cirugías de alta complejidad. En el Caso 1 se pudo analizar las relaciones del tumor con las estructuras adyacentes para minimizar el abordaje. En el Caso 2 permitió comprender la anatomía post-operatoria previa del paciente, para determinar la trayectoria del abordaje transnasal endoscópico y la necesidad de ampliar su exposición, logrando la resección tumoral completa. En el Caso 3 permitió obtener las coordenadas estereotáxicas y trayectoria de una lesión sin representación tomográfica. Conclusión: En casos de no contar con costosos sistemas de neuronavegación o estereotáxia el software OsiriX es una alternativa a la hora de planificar la cirugía, con el objetivo de disminuir el trauma y la morbilidad operatoria. PMID:25165617

  4. Libraries in Texas: MedlinePlus

    MedlinePlus

    ... this page, please enable JavaScript. Amarillo Texas Tech University Health Sciences Center Harrington Library of the Health ... parrish_medical_libr.asp El Paso Texas Tech University Health Sciences Center at El Paso Gallo Library ...

  5. 1. GENERAL STREET VIEW LOOKING SOUTH ON CONVENT AVE. FROM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. GENERAL STREET VIEW LOOKING SOUTH ON CONVENT AVE. FROM INTERSECTION OF SOUTH CONVENT AVE. AND WEST KENNEDY ST. - Barrio Libre, West Kennedy & West Seventeenth Streets, Meyer & Convent Avenues, Tucson, Pima County, AZ

  6. 2. GENERAL STREET VIEW LOOKING WEST ON KENNEDY ST. FROM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. GENERAL STREET VIEW LOOKING WEST ON KENNEDY ST. FROM INTERSECTION OF SOUTH CONVENT AVE. AND WEST KENNEDY ST. - Barrio Libre, West Kennedy & West Seventeenth Streets, Meyer & Convent Avenues, Tucson, Pima County, AZ

  7. 3. GENERAL STREET VIEW LOOKING WEST ON KENNEDY FROM JUST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. GENERAL STREET VIEW LOOKING WEST ON KENNEDY FROM JUST SOUTH OF SOUTH CONVENT AVE. AND WEST KENNEDY ST. - Barrio Libre, West Kennedy & West Seventeenth Streets, Meyer & Convent Avenues, Tucson, Pima County, AZ

  8. 6. GENERAL VIEW LOOKING SOUTHWEST TO REAR OF HOUSES FROM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. GENERAL VIEW LOOKING SOUTHWEST TO REAR OF HOUSES FROM SOUTH OF 432-436 SOUTH CONVENT AVE. TO OTHER SIDE OF BLOCK. - Barrio Libre, West Kennedy & West Seventeenth Streets, Meyer & Convent Avenues, Tucson, Pima County, AZ

  9. Is the basal area of maize internodes involved in borer resistance?

    PubMed Central

    2011-01-01

    Background To elucidate the role of the length of the internode basal ring (LIBR) in resistance to the Mediterranean corn borer (MCB), we carried out a divergent selection program to modify the LIBR using two maize synthetic varieties (EPS20 and EPS21), each with a different genetic background. We investigated the biochemical mechanisms underlying the relationship between the LIBR and borer resistance. Selection to lengthen or shorten the LIBR was achieved for each synthetic variety. The resulting plants were analyzed to determine their LIBR response, growth, yield, and borer resistance. Results In the synthetic variety EPS20 (Reid germplasm), reduction of the LIBR improved resistance against the MCB. The LIBR selection was also effective in the synthetic variety EPS21 (non-Reid germplasm), although there was no relationship detected between the LIBR and MCB resistance. The LIBR did not show correlations with agronomic traits such as plant height and yield. Compared with upper sections, the internode basal ring area contained lower concentrations of cell wall components such as acid detergent fiber (ADF), acid detergent lignin (ADL), and diferulates. In addition, some residual 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3-(4H)-one (DIMBOA), a natural antibiotic compound, was detected in the basal area at 30 days after silking. Conclusion We analyzed maize selections to determine whether the basal area of maize internodes is involved in borer resistance. The structural reinforcement of the cell walls was the most significant trait in the relationship between the LIBR and borer resistance. Lower contents of ADF and ADL in the rind of the basal section facilitated the entry of larvae in this area in both synthetic varieties, while lower concentrations of diferulates in the pith basal section of EPS20 facilitated larval feeding inside the stem. The higher concentrations of DIMBOA may have contributed to the lack of correlation between the LIBR and borer resistance in

  10. Effect of Surfactant Supplying with Refrigerant Vapor on Absorption Enhancement

    NASA Astrophysics Data System (ADS)

    Gao, Hongtao; Matsuzaki, Tetsuya; Wang, Jianfeng; Hihara, Eiji

    For the absorption of water vapor into the aqueous lithium bromide solution, eight-carbon alcohol additives such as 2-ethyl-1-hexanolhave been commonly used to improve the absorption process. However, as additives six-carbon and seven-carbon alcohols were not been tested experimentally very much. In present study, absorption of water vapor into the 62 wt% LiBr solution with several six-carbon and seven carbon alcohol additives such as 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-hexanol, 2 , 4-dimethyl-3-pentanol, 4-heptanol, 2-heptanol and 1-heptanol were investigated by using a simple stagnant pool absorber. Besides using the conventional method which mixing additive into LiBr solution, vapor phase adding method was experimented. Surface tensions of aqueous LiBr solution with different surfactant also were measured by Welhelmy plate method. Absorption of water vapor into the LiBr solution with 2-ethyl-1-hexanol and 1-heptanol were also experimented in falling film absorber by vapor phase adding method. The result showed that the lower the surface tension of LiBr aqueous solution with an additive, the better the effect of absorption enhancement by the corresponding additive, and vapor phase adding method is effective for the absorption of water vapor into the LiBr aqueous solution.

  11. Intelligent Detector Design

    SciTech Connect

    Graf, N.; Cassell, R.; Johnson, T.; McCormick, J.; Magill, S.; Kuhlmann, S.; /Argonne

    2007-02-13

    At a future e+e- linear collider, precision measurements of jets will be required in order to understand physics at and beyond the electroweak scale. Calorimetry will be used with other detectors in an optimal way to reconstruct particle 4-vectors with unprecedented precision. This Particle Flow Algorithm (PFA) approach is seen as the best way to achieve particle mass resolutions from dijet measurements in the range of {approx} 30%/{radical}E, resulting in innovative methods for choosing the calorimeter technology and optimizing the detector design.

  12. Influence of Alpha-Beams with Energy of 30 MeV on Wave Propagation in the Belousov-Zhabotinsky Reaction

    SciTech Connect

    Artamonov, D. N.; Priselkova, A. B.; Spassky, A. V.; Trukhanov, K. A.

    2007-11-26

    The generation of leading centers was observed in an oscillatory reaction of the Belousov-Zhabotinsky type under the action of collimated radiation with high linear energy transfer. Threshold values of the absorbed dose for the generation and complete quenching of autowaves were estimated. For modeling the effect of hard ionizing radiation on the Belousov-Zhabotinsky reaction, we proposed a modified radicalator model taking into account the interaction of reactants with {sup {center_dot}}OH radical, which is produced in the course of irradiation as a result of the radiolysis of water.

  13. The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

    SciTech Connect

    Keyhani, M; Miller, W A

    1999-11-14

    Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller's capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.

  14. Humectant use in the cathodic protection of reinforced concrete

    SciTech Connect

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Russell, James H.; Bullard, Sophie J.; Cramer, Stephen D.; Collins, W.K.; Bennett, J.E.; Laylor, H.M.

    2000-11-01

    Use of humectants to improve the thermal-sprayed zinc anode performance during the cathodic protection (CP) of reinforced concrete was examined. A humectant is a hygroscopic material. It is applied onto the surface of the zinc anode to keep the concrete-anode interface moist and a good conductor. The thermodynamics of humectants are discussed. Laboratory results are presented on the effects of using lithium bromide (LiBr) and lithium nitrate (LiNO{sub 3}) as humectants in galvanic cathodic protection (GCP) and impressed current cathodic protection (ICCP) systems, in high and low relative humidities, and on new and previously electrochemically aged CP systems. LiNO{sub 3} and LiBr promoted more effective CP performance. Both improved the performance of aged slabs, suggesting that application of humectants onto existing CP systems would be of benefit. Microscopy showed that humectant-treated slabs develop the same cement-reaction zone, zinc anode structures as untreated slabs. Microscopy of LiBr-treated slabs revealed that the highest concentration of bromide was in the reaction zone. In GCP tests, LiBr was more effective than LiNO{sub 3}. In accelerated ICCP tests, LiNO{sub 3} was more effective than LiBr. It was surmised that bromide could be oxidized in the high-voltage accelerated ICCP tests. At the lower impressed currents of most installed ICCP systems, LiBr may perform as well as or better than LiNO{sub 3}.

  15. Humectant use in the cathodic protection of reinforced concrete

    SciTech Connect

    Holcomb, G.R.; Covino, B.S. Jr.; Russell, J.H.; Bullard, S.J.; Cramer, S.D.; Collins, W.K.; Bennett, J.E.; H.M. Laylor

    2000-03-01

    The use of humectants to improve the thermal-sprayed zinc anode performance during the cathodic protection (CP) of reinforced concrete is examined. A humectant is a hygroscopic material. It is applied onto the surface of the zinc anode to keep the concrete-anode interface moist and a good conductor. The thermodynamics of humectants are discussed. Laboratory results are presented on the effects of using LiBr and LiNO{sub 3} as humectants in galvanic (GCP) and impressed current (ICCP) systems, in high and low relative humidities, and on new and previously electrochemically aged CP systems. LiNO{sub 3} and LiBr promoted more effective CP performance. Both improved the performance of aged slabs, suggesting that application of humectants onto existing CP systems would be of benefit. Microscopy showed that humectant-treated slabs develop the same cement-reaction zone-zinc anode structures as untreated slabs. Microscopy of LiBr-treated slabs revealed that the highest concentration of bromide was in the reaction zone. In GCP tests, LiBr was more effective than LiNO{sub 3}. In accelerated ICCP tests, LiNO{sub 3} was more effective than LiBr. It was surmised that bromide could be oxidized in the high-voltage accelerated ICCP tests. At the lower impressed currents of most installed ICCP systems, LiBr may perform as well as or better than LiNO{sub 3}.

  16. Communication: An unusual halogen-bonding motif: the LiBr···BrF dimer as a model system.

    PubMed

    McDowell, Sean A C; Joseph, Jerelle A

    2012-11-01

    A stable complex, LiBr···BrF, is predicted in which the negative Br atom of LiBr is anchored to the Br atom of BrF by a halogen bond, while the positively charged Li atom interacts with the lone pair electron density on the Br atom of BrF in a direction roughly perpendicular to the halogen bond. As far as we are aware, this is the first reported instance of an atom of one diatomic molecule (Br of BrF) being bonded to two different, oppositely charged atoms (Li and Br) of another diatomic molecule (LiBr). Other less stable dimers of LiBr and BrF were predicted and compared with this novel complex. PMID:23145710

  17. Modeling of Liquid Film along Absorber Cylinders in an Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Yamanaka, Tomofumi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional liquid film model of LiBr solution falling along absorber cylinders has been studied to obtain boundary conditions for computing vapor flow in the absorber-evaporator of an absorption chiller. The model was established based on the assumptions that LiBr concentration and temperature profiles in the liquid film obey the third order polynomial expressions. It was indicated that mass flux and absorbed heat on the liquid surface can be calculated with simple numerical computations on the present analytical model. The overall heat transfer coefficient and total absorbed mass per second calculated with the present liquid film model was compared with experimental data for validation. The results calculated with the present model showed good agreement with the experimental data. Then, it was concluded the present model was useful enough for determining surface conditions on the LiBr liquid film around absorber cylinders.

  18. ESR Study on Irradiated Ascorbic Acid Single Crystal

    SciTech Connect

    Tuner, H.; Korkmaz, M.

    2007-04-23

    Food irradiation is a 'cold' process for preserving food and has been established as a safe and effective method of food processing and preservation after more than five decades of research and development. The small temperature increase, absence of residue and effectiveness of treatment of pre-packed food are the main advantages. In food industry, ascorbic acid and its derivatives are frequently used as antioxidant agents. However, irradiation is expected to produces changes in the molecules of food components and of course in the molecules of the agents added as preservation agents such as ascorbic acid. These changes in the molecular structures could cause decreases in the antioxidant actions of these agents. Therefore, the radiation resistance of these agents must be known to determine the amount of radiation dose to be delivered. Electron spin resonance (ESR) is one of the leading methods for identification of intermediates produced after irradiation. ESR spectrum of irradiated solid powder of ascorbic acid is fairly complex and determinations of involved radical species are difficult. In the present work, single crystals of ascorbic acid irradiated by gamma radiation are used to determine molecular structures of radiation induced radicalic species and four radicalic species related in pair with P21 crystal symmetry are found to be responsible from experimental ESR spectrum of gamma irradiated single crystal of ascorbic acid.

  19. Espectroscopía de Microondas en Jets Supersónicos

    NASA Astrophysics Data System (ADS)

    Alonso, J. L.; López, J. C.; Lesarri, A.; Blanco, S.; Sanz, M. E.; Mata, S.; Cocinero, J. E.; Sánchez, R.

    Complejos con Enlace de Hidrógeno. El entorno de bajas temperaturas de una expansión supersónica es un excelente laboratorio para estudiar el comportamiento conformacional de los complejos con enlace de hidrógeno. Nuestro grupo ha observado por vez primera enlaces de hidrógeno axial y ecuatorial en los complejos de tetrahidropirano, sulfuro de pentametileno y sulfuro de trimetileno con HCl y HF [1-6] generados en las expansiones adiabáticas en He, Ne o Ar y caracterizados por espectroscopía de microondas con transformadas de Fouier. Existe controversia a la hora de considerar a las interacciones C-H\\cdotsO como enlaces de hidrógeno o como simples interacciones de van der Waals. Las interacciones C-H\\cdotsO han sido estudiadas en el dímero del dimetil eter generado en la expansión supersónica y caracterizado por espectroscopía de microondas [7]. Estas interacciones se han analizado en los complejos formados entre los alcanos sustituidos del trifluorometano y difluorometano con oxirano [8] caracterizándose la existencia de interacciones C-F\\cdotsH-C que contribuyen a la estabilización de estos complejos. Ablación Láser: Estructura de Aminoácidos. Los aminoácidos poseen puntos de fusión elevados (>200oC) y se presentan en fases condensadas como formas dipolares (+H3N-CH(R)-COO-) distintas de las neutras de las cadenas polipéptidas. Con el fin de obtener la estructura de estas formas neutras es necesario experimentar en fase gas, en un entorno libre de interacciones como el de una expansión supersónica. Para solventar el problema de su baja presión de vapor, se ha diseñado un nuevo instrumento que combina la espectroscopía de microondas en jet supersónicos con técnicas de ablación láser [9] que evita los métodos de vaporización por calentamiento que conducen a la descomposición de los aminoácidos. Diversos confórmeros de los aminoácidos naturales de la prolina [10], valina [11], cis- y trans- hidroxiprolina, serina, cisteina, ldots

  20. Exploring Reflective Teaching through Informed Journal Keeping and Blog Group Discussion in the Teaching Practicum (Exploración de la enseñanza reflexiva en la práctica docente a través de la escritura informada de diarios y de discusiones grupales mediante "blogs")

    ERIC Educational Resources Information Center

    Insuasty, Edgar Alirio; Zambrano Castillo, Lilian Cecilia

    2010-01-01

    This article reports the findings of a study which examined how student teachers could be empowered as more reflective practitioners through journal keeping and blog group discussions. It was carried out with six student teachers who developed their practicum over six months. Data were collected through journals, blogs, metaphors, conferences and…

  1. Improving Eleventh Graders' Reading Comprehension through Text Coding and Double Entry Organizer Reading Strategies (Mejoramiento de la comprensión lectora de estudiantes de grado once mediante las estrategias de lectura de codificación de texto y organizador de doble entrada)

    ERIC Educational Resources Information Center

    Mahecha, Rocío; Urrego, Stella; Lozano, Erika

    2011-01-01

    In this article we report on an innovation project developed with a group of eleventh graders at a public school in Bogotá. Its aim was to encourage students to improve reading comprehension of texts in English. It was conducted taking into account students' needs, interests and level of English. To do it, we implemented two reading…

  2. New Educational Environments Aimed at Developing Intercultural Understanding while Reinforcing the Use of English in Experience-Based Learning (Nuevos entornos educativos destinados a desarrollar la comprensión intercultural y a reforzar el uso del inglés mediante el aprendizaje basado en experiencias)

    ERIC Educational Resources Information Center

    Bruguier, Leonard R.; Greathouse Amador, Louise M.

    2012-01-01

    New learning environments with communication and information tools are increasingly accessible with technology playing a crucial role in expanding and reconceptualizing student learning experiences. This paper reviews the outcome of an innovative course offered by four universities in three countries: Canada, the United States, and Mexico. Course…

  3. A Computer Simulation Using Spreadsheets for Learning Concept of Steady-State Equilibrium

    ERIC Educational Resources Information Center

    Sharda, Vandana; Sastri, O. S. K. S.; Bhardwaj, Jyoti; Jha, Arbind K.

    2016-01-01

    In this paper, we present a simple spreadsheet based simulation activity that can be performed by students at the undergraduate level. This simulation is implemented in free open source software (FOSS) LibreOffice Calc, which is available for both Windows and Linux platform. This activity aims at building the probability distribution for the…

  4. SITE CHARACTERIZATION LIBRARY: VOLUMN 1 (RELEASE 2.5)

    EPA Science Inventory

    This CD-ROM, Volume 1, Release 2.5, of EPA's National Exposure Research Laboratory (NERL - Las Vegas) Site Characterization Library, contains additional electronic documents and computer programs related to the characterization of hazardous waste sites. EPA has produced this libr...

  5. CHARACTERIZATION AND PHYSICAL MAPPING OF MAIZE BAC LIBRARIES USING HIGH DENSITY BAC FILTER HYBRIDIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A HindIII and an EcoRI maize BAC library have been constructed from maize inbred line B73. Use of both libraries to make a physical map should minimize the under representation of certain genomic regions caused by the use of a particular restriction enzyme. High-density filter sets from the two libr...

  6. Preguntas frecuentes SmokefreeTXT | Smokefree Español

    Cancer.gov

    Reciba gratuitamente estímulos para dejar de fumar, consejos y recomendaciones 24 horas al día, los 7 días de la semana en su celular con SmokefreeTXT en Español. Envíe LIBRE al 47848 para suscríbirse.

  7. Lithium disulfide battery

    DOEpatents

    Kaun, Thomas D.

    1988-01-01

    A negative electrode limited secondary electrochemical cell having dense FeS.sub.2 positive electrode operating exclusively on the upper plateau, a Li alloy negative electrode and a suitable lithium-containing electrolyte. The electrolyte preferably is 25 mole percent LiCl, 38 mole percent LiBr and 37 mole percent KBr. The cell may be operated isothermally.

  8. Stable lithium electrodeposition in salt-reinforced electrolytes

    NASA Astrophysics Data System (ADS)

    Lu, Yingying; Tu, Zhengyuan; Shu, Jonathan; Archer, Lynden A.

    2015-04-01

    Development of high-energy lithium-based batteries that are safe remains a challenge due to the non-uniform lithium electrodeposition during repeated charge and discharge cycles. We report on the effectiveness of lithium bromide (LiBr) salt additives in a common liquid electrolyte (i.e. propylene carbonate (PC)) on the stability of lithium electrodeposition. From galvanostatic cycling measurements, we find that the presence of LiBr in PC provides more than 20-fold enhancement in cell lifetime over the control LiTFSI/PC electrolyte. Batteries containing 30 mol% LiBr additive in the electrolytes are able to cycle stably for at least 1.8 months with no observations of cell failure. From galvanostatic polarization measurements, an electrolyte containing 30 mol% LiBr shows a maximum improvement in lifetime. The formation of uneven lithium electrodeposits is significantly suppressed by the Br-containing SEI layers, evidenced by impedance spectra, post-mortem SEM and XPS analyses. The study also concludes that good solubility of halogenated salts is not necessary for achieving the observed improvements in cell lifetime.

  9. Speech of italian ambassador

    SciTech Connect

    2008-04-09

    L'ambassadeur italien (nom?)fait un discours sur l'aspect de la recherche au Cern, une organisation internationale qui a comme but la connaissance dans sa forme la plus pure et libre d'un intérêt planétaire. Il remet un prix au DG C.Rubbia qui lui remercie en français

  10. Are Dropout and Degree Completion in Doctoral Study Significantly Dependent on Type of Financial Support and Field of Research?

    ERIC Educational Resources Information Center

    van der Haert, Margaux; Arias Ortiz, Elena; Emplit, Philippe; Halloin, Véronique; Dehon, Catherine

    2014-01-01

    In this article, the determinants of "time to dropout" from doctoral studies and "time to PhD completion" are studied using a discrete-time competing risks survival analysis for a sample of 3092 doctoral candidates from the Université libre de Bruxelles. Not surprisingly, results show that students supported with research…

  11. Palabras clave SmokefreeTXT | Smokefree Español

    Cancer.gov

    Reciba gratuitamente estímulos para dejar de fumar, consejos y recomendaciones 24 horas al día, los 7 días de la semana en su celular con SmokefreeTXT en Español. Envíe LIBRE al 47848 para suscríbirse.

  12. Examining Value Change in MOOCs in the Scope of Connectivism and Open Educational Resources Movement

    ERIC Educational Resources Information Center

    Ozturk, Hayriye Tugba

    2015-01-01

    Massive Open Online Courses (MOOCs) came to prominence with Open Educational Resources Movement (OERM). It was based upon the idea of libre in removal of some permission barriers and gratis in removing the price barrier (Suber, 2008) in learning resources. In line with the theoretical underpinnings of OERM, MOOCs embody primary characteristics of…

  13. Speech of italian ambassador

    ScienceCinema

    None

    2011-04-25

    L'ambassadeur italien (nom?)fait un discours sur l'aspect de la recherche au Cern, une organisation internationale qui a comme but la connaissance dans sa forme la plus pure et libre d'un intérêt planétaire. Il remet un prix au DG C.Rubbia qui lui remercie en français

  14. New concept of enhanced monitoring station for urban air application

    NASA Astrophysics Data System (ADS)

    Allegrini, Ivo; Febo, Antonio; Giliberti, Claudia

    1995-05-01

    An advanced monitoring station was set up in the center of Milan, Italy. It is made up of several instruments for the measurement of atmospheric pollutants, including a DOAS system which is able to provide information of the time evolution of several primary and secondary atmospheric pollutants. A radioactivity monitor provides information about the time evolution of Radon daughters, thereby providing information about the evolution of the boundary layer. It is shown that pollution by primary pollutants can be described through a very simple model based on Radon observation. Secondary pollutants, like ozone and nitrogen dioxide can also be described by the same model. Observation in strong advective condition and during stability periods show that the presence of large concentration of nitrogen dioxide is due to radicalic processes which are also responsible for the formation of formaldehyde. The role of nitrous acid in the formation of radicals is also discussed.

  15. Lithiase géante sur enterocystoplastie

    PubMed Central

    Elmortaji, Khalid; Elomri, Ghassane; Bennani, Saad; Rabii, Redouane; Aboutaib, Rachid; Meziane, Fethi

    2014-01-01

    La formation des lithiases est une complication fréquente des entérocystoplasties après cystectomie radicale pour tumeur de vessie infiltrante. Le délai d'apparition dépend des facteurs de risque favorisants notamment les infections urinaires. Néanmoins la survenue de lithiase géante sur néovessie reste exceptionnelle, seulement 5 cas ont été rapportés dans la littérature. Nous rapportons dans ce travail, le cas d'une lithiase géante compliquant une entérocystoplastie chez un malade suivi pour tumeur de vessie infiltrante. PMID:25932070

  16. Characteristic of Absorption Heat Transfer using LiBr+LiI Solution

    NASA Astrophysics Data System (ADS)

    Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

    LiBr-H20 absorption chiller is widely used in Japan, and many research have been made for absorption characteristic in terms of enhancing heat transfer. Another study have been performed for widening working range with higher crystallization limits, and it was reported that adding LiI salt to LiBr-H20 working fluid provide about 5 [mass%] higher crystallization limit under the condition of absorption pressure range. It is necessary to reveal absorption heat transfer performance to utilize this working fluid pair for absorption chiller. In this study absorption heat transfer characteristic was investigated for horizontal and vertical tube. As a result, it was found that heat transfer coefficient increased as mass flow rate of solution increased and mass concentration of solution decrease and that these characteristic were almost the same as LiBr solution, though this solution gave slightly less heat transfer coefficient than LiBr solution.

  17. Visualization of thermal behavior of fluid by laser holographic interferometry

    NASA Astrophysics Data System (ADS)

    Kurosaki, Y.; Kashiwagi, T.

    1990-01-01

    Visualization of four phenomena associated with thermal and fluid flow fields effectively using laser holographic interferometry are reviewed: airflow in a narrow passage between louver arrays, steam absorption into an aqueous solution of LiBr, Marangoni convection effect of steam absorption into a solution with the addition of high molecular weight alcohol, and pressure distribution on a plate induced by air-jet impingement. The observation result obtained in the first case is useful for designing louvered fins used in a heat exchanger. In the second case, the mass diffusivity of water into a solution of LiBr is shown to be measurable. In the third case, the effect of Marangoni convection on steam absorption is both qualitatively and quantitatively elucidated. The last case is a new visualization method of fluctuating pressure on a wall that can be used to resolve eddy-motion behavior near a wall.

  18. Country watch: Peru.

    PubMed

    Mazzotti, G

    1995-01-01

    In 1991-1992, Via Libre, a nongovernmental organization (NGO), developed an information program for the general public in Lima using a portable pavilion. The metallic structure is 32 square meters and houses 30 posters with prevention messages. Collaboration with another NGO, Instituto Generacion, resulted in the production of a 7 minute video of basic information that is shown continuously at the pavilion. Facilitators distribute printed materials. Occasionally, a third NGO, Asociacion Germinal, provides street clowns who carry prevention messages to accompany the exhibit. Due to positive public response, the exhibit became "The Information Traveling Pavilion" in 1993; the exhibit has traveled to more than seven cities throughout Peru. Via Libre staff provide local health workers with information update courses and counseling workshops in order to respond to increased public demands for information and support following the activities. 75 private enterprises have provided support for the program. Radio and television collaborate in publicizing the activities. PMID:12289835

  19. Experimental study of evaporation of horizontal films of water-salt solutions

    NASA Astrophysics Data System (ADS)

    Elistratov, S. L.; Morozov, V. S.

    2015-01-01

    The present studies were carried out for the horizontal films (thin layers) of water and water solutions of NaCl, CaCl2, LiCl, and LiBr with different solubility characteristics, as well as with specific features of formation and decay of water hydrates. Required volume of solution Vo of given weight concentration ξo, preliminary heated to the working surface temperature, was put in one step on the horizontal bottom of the bowl, heated to working temperature tCT, by means of volume batchers Thermo Scientific. After evaporation completion, the final mass of solution and form of their residue were registered. At the final stage of evaporation formation of NaCl crystals and water hydrates of CaCl2 · 2H2O, LiCl · H2O, and LiBr · 2H2O occurred.

  20. Quasicharacteristic radiation of relativistic electrons at orientation motion in lithium halides crystals along charged planes and axes

    NASA Astrophysics Data System (ADS)

    Maksyuta, N. V.; Vysotskii, V. I.; Efimenko, S. V.

    2016-07-01

    The paper deals with the investigation of the orientation motion of relativistic electrons in charged (111) planes and charged [110] axes of lithium halides ionic crystals of LiF, LiCl, LiBr and LiI. On the basis of these investigations the spectra of quasicharacteristic radiation for the electron beams with various Lorentz-factors both in planar and axial cases have been calculated numerically.

  1. VizieR Online Data Catalog: Polarisation of a sample of late M dwarfs (Morin+, 2010)

    NASA Astrophysics Data System (ADS)

    Morin, J.; Donati, J.-F.; Petit, P.; Delfosse, X.; Forveille, T.; Jardine, M. M.

    2010-06-01

    We have collected 174 pairs of Stokes I (unpolarised) and V (circularly polarised) spectra with ESPaDOnS at CFHT (2003ASPC..307...41D) between June 2006 and July 2009. All spectra were reduced using the Libre-Esprit pipeline, and the mean I and V line profiles were extracted using the Least-Squares Deconvolution (LSD) technique (Donati et al., 1997MNRAS.291..658D). (3 data files).

  2. Violación del Principio de Equivalencia en Teorías con Dilatón de Cuerdas

    NASA Astrophysics Data System (ADS)

    Landau, S. J.; Sisterna, P. D.; Vucetich, H.

    Se estudian las violaciones al Principio de Equivalencia en Teorías con Dilatón de Cuerdas. En estos modelos, algunas de las constantes fundamentales dependen del espacio y del tiempo. Se muestra que los experimentos de caída libre no tienen aún precisión como para poner límites a los parámetros de la teoría.

  3. Baja California, Mexico

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Sunglint on the surface of the Sea of Cortez near the island of Tiburon (28.5 N, 112.5W) reveals intricate patterns of internal waves under the placid surface. Mexico's state of Sonora and the Sonora Desert is on the mainland and the state of Baja California consists of the entire peninsula. The large bay on the Pacific side of Baja is Laguna Ojo de Libre (Bay of Whales) which is a breeding area for the Pacific Grey Whales.

  4. Lithium bromide chiller technology in gas processing

    SciTech Connect

    Huey, M.A.; Leppin, D.

    1995-12-31

    Lithium Bromide (LiBr) Absorption Chillers have been in use for more than half a century, mainly in the commercial air conditioning industry. The Gas Research Institute and EnMark Natural Gas Company co-funded a field test to determine the viability of this commercial air conditioning technology in the gas industry. In 1991, a 10 MMCFC natural gas conditioning plant was constructed in Sherman, Texas. The plant was designed to use a standard, off-the-shelf chiller from Trane with a modified control scheme to maintain tight operating temperature parameters. The main objective was to obtain a 40 F dewpoint natural gas stream to meet pipeline sales specifications. Various testing performed over the past three years has proven that the chiller can be operated economically and on a continuous basis in an oilfield environment with minimal operation and maintenance costs. This paper will discuss how a LiBr absorption chiller operates, how the conditioning plant performed during testing, and what potential applications are available for LiBr chiller technology.

  5. Evaluation of potential performance additives for the advanced lithium bromide chiller

    SciTech Connect

    Reiner, R.H.; Del Cul, W.; Perez-Blanco, H.; Ally, M.R.; Zaltash, A.

    1991-04-01

    The effectiveness and stability of potential heat-and-mass transfer (performance) additives for an advanced lithium bromide (LiBr) chiller were evaluated in a series of experimental studies. These studies of additive effectiveness and stability were necessary because many currently used performance additives decompose at the high generator temperatures (220{degrees}C to 260{degrees}C) desired for this particular advanced LiBr chiller. For example, one common performance additive, 2-ethyl-l-hexanol (2EH), reacts with the corrosion inhibitor, lithium chromate (Li{sub 2}CrO{sub 4}), even at moderate generator temperatures ({ge}180{degrees}C). These stability problems can be mitigated by using less reactive corrosion inhibitors such as lithium molybdate (Li{sub 2}MoO{sub 4}) and by using more stable performance additives such as 1-heptanol (HEP) or 1H,1H,7H-dodecafluoro-1-heptanol (DFH). There seems to be a trade-off between additive stability and effectiveness: the most effective performance additives are not the most stable additives. These studies indicate that HEP or DFH may be effective additives in the advanced LiBr chiller if Li{sub 2}MoO{sub 4} is used as a corrosion inhibitor.

  6. Application of the groundwater-balance equation to indicate interbasin and vertical flow in two semi-arid drainage basins, Mexico

    NASA Astrophysics Data System (ADS)

    Carrillo-Rivera, J. J.

    2000-09-01

    coeficiente de almacenamiento (S). En particular, la ecuación de balance de agua subterránea proporciona resultados poco fiables cuando el flujo vertical es ignorado o no puede ser evaluado de forma adecuada. El flujo vertical se identifica por un incremento de temperatura del agua subterránea, que puede llegar a superar la temperatura ambiental en hasta 23 °C. La presencia de fallas regionales y las extracciones pueden favorecer el flujo vertical. Cuando éste es ignorado, aumenta la incertidumbre en la estimación del coeficiente de almacenamiento mediante un balance de agua subterránea. El valor obtenido con este médodo (S=0,19) es característico de acuíferos libres, pero resulta varios órdenes de magnitud mayor que el que sería esperable teniendo en cuenta las condiciones hidrogeológicas. Estos hallazgos son útiles para evaluar si los recursos de agua subterránea están siendo "sobreexplotados". Las conclusiones obtenidas son instructivas de cara a la aplicación de modelos numéricos de flujo transitorio que no consideran el flujo vertical por densidad.

  7. Spatial neural modulation transfer function of human foveal visual system for equiluminous chromatic gratings.

    PubMed

    Rovamo, J M; Kankaanpää, M I; Hallikainen, J

    2001-06-01

    To determine the spatial modulation transfer function (MTF) of the human foveal visual system for equiluminous chromatic gratings we measured contrast sensitivity as a function of retinal illuminance for spatial frequencies of 0.125-4 c/deg with equiluminous red-green and blue-yellow gratings. Contrast sensitivity for chromatic gratings first increased with luminance, obeying the Rose-DeVries law, but then the increase saturated and contrast sensitivity became independent of light level, obeying Weber's law. Critical retinal illuminance (I(c)) marking the transition point between the laws was found to be independent of spatial frequency at 165 phot. td. According to our detection model of human spatial vision the MTF of the retina and subsequent neural visual pathways (P(c)) is directly proportional to radicalI(c). Hence, P(c) is independent of spatial frequency, reflecting the lack of precortical lateral inhibition for equiluminous chromatic stimuli in spatiochromatically opponent retinal ganglion cells and dLGN neurons. PMID:11348648

  8. Radiosensitivities of parabens and characterization of the radical species induced in this class of antimicrobial agents after gamma irradiation

    NASA Astrophysics Data System (ADS)

    Üstündaǧ, Ilknur; Korkmaz, Özden

    Radiosensitivities of methyl, ethyl, propyl and butyl parabens and sodium salts of methyl and propyl parabens (hereafter, MP, EP, PP, BP, SMP and SPP, respectively) were investigated by monitoring, through electron spin resonance (ESR) spectroscopy, the evolution under different experimental conditions of characteristic features of the radicalic species produced upon irradiation by gamma radiation. While ESR spectra of the studied parabens consisted of the sum of broad and narrow resonance lines of different microwave saturation and thermal characteristics, those of sodium salts appeared to consist of the sum of two overlapping narrow resonance lines. Radical species presented different room and high-temperature decay characteristics, depending on the extent of the cage effect created by the lattice networks on these species. A model based on the presence of two radical species presenting different spectroscopic and kinetic features described best the experimental data collected for parabens and their sodium salts. Radiation yields of the studied parabens towards gamma radiation were calculated to be low (G≤10-2), providing the opportunity of using these antimicrobial agents in food, cosmetics and drugs to be sterilized by radiation without much loss from their antimicrobial activities.

  9. Association grossesse et pseudomyxome péritonéal secondaire à une tumeur mucineuse borderline de l’ovaire: à propos d’un cas et revue de la littérature

    PubMed Central

    Jayi, Sofia; Fatemi, Hind; Bouguern, Hakima; Chaara, Hikmat; Melhouf, My Abdelilah

    2012-01-01

    Les tumeurs mucineuses de l’ovaire représentent 20% des tumeurs épithéliales. La forme borderline en est une entité particulière et est de survenue rare particulièrement au cours de la grossesse (1/10 000 à 1/50 000). Nous rapportons le cas d’une patiente de 35 ans G4P3, présentant une grossesse de 22SA associée à une tumeur ovarienne droite gélatineuse, rompue avec implants péritonéaux, dont l’examen extemporané de l’annexectomie a trouvé une tumeur mucineuse au minimum borderline. Une chirurgie radicale a été faite avec à l’étude histologique définitive: une tumeur ovarienne mucineuse borderline avec tératome mature et pseudomyxome péritonéal. A travers ce cas rare et à la lumière d’une revue de la littérature nous insistons sur les caractéristiques épidémiologiques diagnostiques, thérapeutiques et pronostiques de cette rare entité tout en précisant les particularités de son association avec la grossesse. PMID:23330030

  10. Mechanism of heating of pre-formed plasma electrons in relativistic laser-matter interaction

    SciTech Connect

    Paradkar, B. S.; Krasheninnikov, S. I.; Beg, F. N.

    2012-06-15

    The role of the longitudinal ambipolar electric field, present inside a pre-formed plasma, in electron heating and beam generation is investigated by analyzing single electron motion in the presence of one electromagnetic plane wave and 'V' shaped potential well (constant electric field) in a one dimensional slab approximation. It is shown that for the electron confined in an infinite potential well, its motion becomes stochastic when the ratio of normalized laser electric field a{sub 0}, to normalized longitudinal electric field E{sub z}, exceeds unity, i.e., a{sub 0}/E{sub z} Greater-Than-Or-Equivalent-To 1. For a more realistic potential well of finite depth, present inside the pre-formed plasma, the condition for stochastic heating of electrons gets modified to 1 Less-Than-Or-Equivalent-To a{sub 0}/E{sub z} Less-Than-Or-Equivalent-To {radical}(L), where L is the normalized length of the potential well. The energy of electron beam leaving such a potential well and entering the solid scales {approx}a{sub 0}{sup 2}/E{sub z}, which can exceed the laser ponderomotive energy ({approx}a{sub 0}) in the stochastic regime.

  11. A Possible Prebiotic Peptide Formation from Glycinamide and Related Compounds

    NASA Astrophysics Data System (ADS)

    Yanagawa, Hiroshi; Nishizawa, Masato; Kojima, Kiyotsugu

    1984-12-01

    We examined an experimental approach to the genesis of protocells in the primeval sea. Glycine polymers with an average chain length of 12 were formed from glycinamide in fluctuating systems (pH 7.2, 80°C, 20 cycles). The resulting glycine polymers gave aggregated leaflet-like structures. A solution of the glycine polymers provided stacked disc-shaped structures in the presence of LiBr and gave sheet structures in the presence of dichloroacetic acid. The shapes of these organized structures were correlated with their molecular structures.

  12. PyGlobal: A toolkit for automated compilation of DFT-based descriptors.

    PubMed

    Nath, Shilpa R; Kurup, Sudheer S; Joshi, Kaustubh A

    2016-06-15

    Density Functional Theory (DFT)-based Global reactivity descriptor calculations have emerged as powerful tools for studying the reactivity, selectivity, and stability of chemical and biological systems. A Python-based module, PyGlobal has been developed for systematically parsing a typical Gaussian outfile and extracting the relevant energies of the HOMO and LUMO. Corresponding global reactivity descriptors are further calculated and the data is saved into a spreadsheet compatible with applications like Microsoft Excel and LibreOffice. The efficiency of the module has been accounted by measuring the time interval for randomly selected Gaussian outfiles for 1000 molecules. © 2016 Wiley Periodicals, Inc. PMID:26990776

  13. State-of-the-Art Review on Crystallization Control Technologies for water/LiBr Absorption Heat Pumps

    SciTech Connect

    Wang, Kai; Abdelaziz, Omar; Kisari, Padmaja; Vineyard, Edward Allan

    2011-01-01

    The key technical barrier to using water/lithium bromide (LiBr) as the working fluid in aircooled absorption chillers and absorption heat-pump systems is the risk of crystallization when the absorber temperature rises at fixed evaporating pressure. This article reviews various crystallization control technologies available to resolve this problem: chemical inhibitors, heat and mass transfer enhancement methods, thermodynamic cycle modifications, and absorption system-control strategies. Other approaches, such as boosting absorber pressure and J-tube technology, are reviewed as well. This review can help guide future efforts to develop water/LiBr air-cooled absorption chillers and absorption heatpump systems.

  14. Calculation tool for transported geothermal energy using two-step absorption process

    DOE Data Explorer

    Kyle Gluesenkamp

    2016-02-01

    This spreadsheet allows the user to calculate parameters relevant to techno-economic performance of a two-step absorption process to transport low temperature geothermal heat some distance (1-20 miles) for use in building air conditioning. The parameters included are (1) energy density of aqueous LiBr and LiCl solutions, (2) transportation cost of trucking solution, and (3) equipment cost for the required chillers and cooling towers in the two-step absorption approach. More information is available in the included public report: "A Technical and Economic Analysis of an Innovative Two-Step Absorption System for Utilizing Low-Temperature Geothermal Resources to Condition Commercial Buildings"

  15. Ni-Catalyzed Enantioselective C-Acylation of α-Substituted Lactams.

    PubMed

    Hayashi, Masaki; Bachman, Shoshana; Hashimoto, Satoshi; Eichman, Chad C; Stoltz, Brian M

    2016-07-27

    A new strategy for catalytic enantioselective C-acylation to generate α-quaternary-substituted lactams is reported. Ni-catalyzed three-component coupling of lactam enolates, benzonitriles, and aryl halides produces β-imino lactams that then afford β-keto lactams by acid hydrolysis. Use of a readily available Mandyphos-type ligand and addition of LiBr enable the construction of quaternary stereocenters on α-substituted lactams to form β-keto lactams in up to 94% ee. PMID:27373124

  16. Evaluation of alkali bromide salts for potential pyrochemical applications

    SciTech Connect

    Tripathy, P.K.; Gutknecht, T.Y.; Herrmann, S.D.; Fredrickson, G.L.; Lister, T.E.

    2013-07-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr{sub 3} (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973 K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673 K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electro-deposit high purity RE metals at comparatively lower operating temperatures. (authors)

  17. Structure of protein surfactant complexes as studied by small-angle neutron scattering and dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Chodankar, S.; Aswal, V. K.; Hassan, P. A.; Wagh, A. G.

    2007-08-01

    The structure of protein-surfactant complexes of bovine serum albumin (BSA) and sodium dodecyl sulfate (SDS) has been studied using small-angle neutron scattering (SANS) and dynamic light scattering (DLS). SANS data indicate that addition of BSA to micellar surfactant solution leads to the formation of a complex that has a fractal structure. The fractal structure has been evaluated using a necklace model considering that the micelle-like aggregates are randomly distributed around the polypeptide chain. We have observed that the structure of protein-surfactant complex is independent of the size of micelles in their pure surfactant solutions. The SDS micelle size was varied using salts LiBr or/and NaBr, where SDS forms larger micelles in presence of NaBr than LiBr. The fractal dimension and the extent of the complex as well as the size and number of micelles attached to the complex have been determined. The micelle-like aggregates bound to protein in the complex are spherical with a much smaller aggregation number than those in pure surfactant solutions. DLS measurements support the above results on the protein-surfactant complexes as obtained using SANS.

  18. Evaluation of Alkali Bromide Salts for Potential Pyrochemical Applications

    SciTech Connect

    Prabhat K. Tripathy; Steven D. Herrmann; Guy L. Fredrickson; Tedd E. Lister; Toni Y. Gutknecht

    2013-10-01

    Transient techniques were employed to study the electrochemical behavior, reduction mechanism and transport properties of REBr3 (RE - La, Nd and Gd) in pure LiBr, LiBr-KBr (eutectic) and LiBr-KBr-CsBr (eutectic) melts. Gd(III) showed a reversible single step soluble-insoluble exchange phenomenon in LiBr melt at 973K. Although La (III), Nd(III) and Gd(III) ions showed reversible behavior in eutectic LiBr-KBr melts, these ions showed a combination of temperature dependent reversible and pseudo-reversible behavior. While both La(III) and Gd(III) showed one step reduction, the reduction of Nd(III) was observed to be a two step process. La metal could be electrodeposited from the ternary electrolyte at a temperature of 673K. Various electrochemical measurements suggest that both binary and ternary bromide melts can potentially be used to electrodeposit high purity RE metals at comparatively lower operating temperatures.

  19. Moving beyond the limits of mass transport in liquid absorbent microfilms through the implementation of surface-induced vortices

    SciTech Connect

    Bigham, S; Yu, DZ; Chugh, D; Moghaddam, S

    2014-02-01

    The slow diffusion of an absorbate molecule into an absorbent often makes the absorption process a rate-limiting step in many applications. In cases involving an absorbate with a high heat of phase change, such as water absorption into a LiBr (lithium bromide) solution, the absorption rate is further slowed due to significant heating of the absorbent. Recently, it has been demonstrated that constraining a LiBr solution film by a hydrophobic porous structure enables manipulation of the solution flow thermohydraulic characteristics. Here, it is shown that mass transport mode in a constrained laminar solution flow can be changed from diffusive to advective. This change in mode is accomplished through stretching and folding the laminar streamlines within the solution film via the implementation of micro-scale features on the flow channel surface. The process induces vortices within the solution film, which continuously bring concentrated solution from the bottom and middle of the solution channel to its interface with the vapor phase, thus leading to a significant enhancement in the absorption rate. The detailed physics of the involved transport processes is elucidated using the LBM (Lattice Boltzmann Method). Published by Elsevier Ltd.

  20. [Not Available].

    PubMed

    Grao-Cruces, Alberto; Loureiro, Nuno; Fernández-Martínez, Antonio; Mota, Jorge

    2016-01-01

    Introducción y objetivos: examinar la asociación del apoyo de los padres y de los amigos con diferentes intensidades de actividad física durante el tiempo libre de adolescentes españoles de ambos sexos.Métodos: un total 352 adolescentes españoles (51.70% chicos; 12-16 años) cumplimentaron el International Physical Activity Questionnarie for Adolescents y un cuestionario validado sobre apoyo social. Se realizaron análisis de regresión linear ajustados por edad.Resultados: el apoyo social de padres y amigos influyó positivamente sobre los niveles de actividad física vigorosa que los adolescentes españoles realizan durante su tiempo libre (β=.226 y β=.285 en chicos y β=.167 y β=.181 en chicas, para el apoyo de padres y amigos respectivamente) y sobre los de intensidad moderada en el caso de las chicas (β=.195 y β=.200, respectivamente).Conclusiones: el apoyo de padres y amigos contribuye a los niveles de actividad física moderada o vigorosa en adolescentes españoles. PMID:27571649

  1. Hydrodynamic characteristics of the western Doñana Region (area of El Abalario), Huelva, Spain

    NASA Astrophysics Data System (ADS)

    Trick, Thomas; Custodio, Emilio

    approximately 0.4-0.6 of that calculated with a soil-balance model. The cross section model was used to study the effect of groundwater ion on water-table depth by subtracting the contribution of vertical flow, calculated by a well-hydraulics formula, to the semiconfined deep aquifer. The result was a decrease in phreatic evapotranspiration, flow into La Rocina Creek, and lagoon-inundation frequency. Replacement of the eucalyptus forest with native vegetation may raise water-table levels and even reactivate old tributaries to La Rocina Creek. La région de Doñana, située dans le sud ouest de l'Espagne, comprend une importante réserve naturelle avec des zones humides, affectée par l'activité humaine. L'exploitation de vastes plantations d'eucalyptus pendant les années 50 et l'usage plus récent des nappes souterraines pour l'irrigation et l'alimentation en eau des centres touristiques côtiers ont modifié le système de flux d'eau souterraine dans cette zone. La présente étude a été réalisée dans le secteur occidental, appelé El Abalario. Ce secteur consiste en une légère élévation située entre l'Océan Atlantique et la ravine de La Rocina. Une couverture variable de sables éoliens, formant une haute crête dunaire côtière, recouvre des sédiments detritiques plio-quaternaires, déposés eux même sur des sables siliceux lesquels reposent à leur tour sur des marnes. Près de la base se trouvent des sables grossiers et des graviers d'origine deltaïque, dont l'épaisseur varie spatialement. Le flux d'eau souterraine est conditionné par l'aquifère semi confinés des graviers et des sables grossiers. Le niveau phréatique de l'aquifère libre des sables fluvio-marins est peu profond, excepté sous les dunes. On y trouve souvent des petites lagunes temporaires peu profondes. Le flux de l'eau souterraine a été simulé dans une section verticale pour vérifier le modèle hydrogéologique conceptuel et la sensibilité aux variations des paramètres. Le mod

  2. Production and fragmentation of the D sup *0 charm meson in e sup + e sup minus annihilations at radical s = 29 GeV

    SciTech Connect

    Low, H.L.

    1987-01-01

    In this thesis, the neutral vector charm meson D{sup *0} has been studied. The data, corresponding to an integrated luminosity of 300 pb{sup {minus}1}, were collected using the High Resolution Spectrometer (HRS). The HRS is located at the PEP e{sup +}e{sup {minus}} storage ring at the Stanford Linear Accelerator Center. The detector subsystems relevant to the analysis are the seventeen layer drift chamber system and the barrel calorimeter system. Both of these devices are located within a solenoidal magnetic field of 1.62 Tesla. The charged particle momentum resolution is {sigma}{sub p}/p {approx} 6 {times} 10{sup {minus}3}p (p in GeV) for the momentum range used in this analysis. The electromagnetic energy resolution of the barrel shower counter system is {sigma}{sub E}/E {approx} 0.16/{radical}E (E in GeV). The radiative decay of the D{sup {asterisk}0} into a scalar charm meson, D{sup 0}, and a photon, {gamma}, where the D{sup 0} decays into a kaon and a pion (K{sup {minus}} {pi}{sup +}) has been observed. The production cross section in units of the point cross section is 0.63 {plus minus} 0.22 for fractional energy Z {ge} 0.5. This results is compared with the result form the JADE collaboration. The fragmentation function is compared with that of the D{sup *+} meson, also measured with the HRS.

  3. Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling.

    PubMed

    Aberg, Anna Cristina; Frykberg, Gunilla Elmgren; Halvorsen, Kjartan

    2010-04-01

    Most falls in older people are due to loss of balance during everyday locomotion, e.g., when initiating walking from sitting; sit-to-walk (STW). It has been considered that the broader stride width in walking that is seen in many people with fear of falling (FoF) does not increase stability, but could be predictive of future falls because of increased medio-lateral (ML) velocity of the body centre of mass (CoM). This study was aimed to examine step-, velocity- and stability-related parameters, focusing on ML stability, in STW performance of people with and without FoF. Ten subjects with FoF and 10 matched controls, aged > or = 70 years, were included. Kinematic and kinetic data were collected in a laboratory. Stability parameters were calculated from a formula implying that the vertical projection of the CoM extrapolated by adding its velocity times a factor radicall/g (height of inverted pendulum divided by gravity) should fall within the base of support (BoS). A related spatial margin of stability (SMoS), defined as the minimum distance from the extrapolated CoM (XCoM) to the boundaries of the BoS, was also calculated. In the phase 'seat-off-second-toe-off', the FoF group had significantly (p<0.05) shorter and broader steps, lower forward but similar ML CoM velocity, and broader CoM and XCoM widths. The FoF group therefore exhibited a disproportionately large sideways velocity compared to the controls. This indicates that STW may be a hazardous transfer for older people with FoF, which should be relevant in assessment and training aimed at preventing falls. PMID:20189390

  4. [In Process Citation].

    PubMed

    Guzmán-Mercado, Elizabeth; Vásquez-Garibay, Edgar M; Troyo-Sanroman, Rogelio; Romero-Velarde, Enrique

    2016-01-01

    Objetivo: identificar los hábitos alimentarios de adolescentes embarazadas en cuatro estados civiles diferentes: casada, cohabita con una pareja, soltera sin pareja y soltera con una pareja. Métodos: en estudio transversal, se incluyeron 321 adolescentes embarazadas de 13-19 años que acudieron al Hospital Civil de Guadalajara Dr. Juan I Menchaca, Guadalajara (Jalisco, México). Se encontraban sanas, en cualquier trimestre del embarazo y pertenecían a un nivel socioe-conómico bajo o medio-bajo. El estado civil se estratificó en: casadas; en unión libre; soltera con una pareja y soltera sin pareja. Se incluyeron datos socio-demográficos, económicos y de hábitos de alimentación. Se utilizaron pruebas de ANOVA, pruebas post-hoc para Chi 2 , razón de momios y modelos de regresión logística. Resultados: la frecuencia de las adolescentes casadas fue de 9,3%, 59,8% en unión libre, 15,3% eran solteras sin pareja y 15,6% solteras con pareja. La baja escolaridad (RM 2,6 [1,5-4,4]) y la ocupación en el hogar (RM 4,47 [1,99-10,0]) predominaron entre las adolescentes en unión libre; la ocupación en el hogar (RM 0,28 [0,127-0,61]) y cenar sin compañía (RM 4,12 [1,62-10,8]) fueron significativamente más frecuentes en adolescentes sin pareja. El consumo de verduras fue menor en las adolescentes casadas y en quienes cohabitaban con pareja; el consumo de frijoles y pan dulce fue menor en adolescentes embarazadas casadas. Conclusión: debido a que ciertas variables y hábitos de alimentación mostraron diferencias entre los grupos es pertinente analizar las adolescentes embarazadas de acuerdo a su estado civil. PMID:27238777

  5. Association entre les hormones sexuelles, les marqueurs de remodelage osseux et la densité minérale osseuse chez des femmes ménopausées d'origine marocaine (étude transversale)

    PubMed Central

    El Maataoui, Aissam; Biaz, Asmae; El Boukhrissi, Fatima; El Machtani, Si; Dami, Abdellah; Bouhsain, Sanae; Bamou, Youssef; El Maghraoui, Abdellah; Ouzzif, Zhor

    2015-01-01

    Introduction Le présent travail se propose d’étudier la relation entre les hormones sexuelles, notamment l’œstradiol et l'indice de l’œstradiol libre, le sulfate de déhydroépiandrosterone et la sex hormone binding globulin, les marqueurs de remodelage osseux et la densité minérale osseuse chez une population de femmes marocaine ménopausées. Méthodes Il s'agit d'une étude transversale, menée sur une période de 6 mois d'octobre 2012 à fin avril 2013 et ayant fait participer deux cent deux (202). Résultats L’œstradiol et l'indice d’œstradiol libre (IEL) ont montré une corrélation négative respectivement à l'ostéocalcine (OC), à la crosslaps (β-CTX) et l'OC (p<0.001). La sulfate de déhydroepiandrosterone S-DHEA a été corrélée positivement à l'OC (p<0.001), alors que e taux sérique de la sex hormone binding globulin (SHBG) l'a été corrélé à la β-CTX et l'OC (p<0.001). Par ailleurs, une corrélation positive a été établie entre la densité minérale osseuse (DMO) au col de fémur et le poids, l'indice de masse corporelle (IMC), l'IEL et la S-DHEA. Une corrélation négative a été retrouvée entre la DMO au col de fémur d'une part et l’âge, la DDR, la SHBG, la β-CTX et l'OC d'une autre part. Conclusion Le présent travail montre que l'augmentation de l’âge et la diminution de l’œstradiol libre expliquent la diminution de la DMO au niveau du col du fémur, alors que l'augmentation du taux sérique de la SHBG et la diminution du poids expliquent la diminution de la DMO au rachis lombaire. PMID:26848353

  6. Low-frequency collective dynamics in deep eutectic solvents of acetamide and electrolytes: A femtosecond Raman-induced Kerr effect spectroscopic study

    NASA Astrophysics Data System (ADS)

    Biswas, Ranjit; Das, Anuradha; Shirota, Hideaki

    2014-10-01

    In this study, we have investigated the ion concentration dependent collective dynamics in two series of deep eutectic solvent (DES) systems by femtosecond Raman-induced Kerr effect spectroscopy, as well as some physical properties, e.g., shear viscosity (η), density (ρ), and surface tension (γ). The DES systems studied here are [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] and [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] with f = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. γ of these DES systems shows near insensitivity to f, while ρ shows a moderate dependence on f. Interestingly, η exhibits a strong dependence on f. In the low-frequency Kerr spectra, obtained via the Fourier transform of the collected Kerr transients, a characteristic band at ˜70 cm-1 is clear in [0.78CH3CONH2 + 0.22{f LiBr + (1 - f )LiNO3}] DES especially at the larger f. The band is attributed to the intermolecular hydrogen bond of acetamide. Because of less depolarized Raman activities of intermolecular/interionic vibrational motions, which are mostly translational (collision-induced or interaction-induced) motions, of spherical ions, the intermolecular hydrogen-bonding band is clearly observed. In contrast, the intermolecular hydrogen-bonding band is buried in the other intermolecular/interionic vibrational motions, which includes translational and reorientational (librational) motions and their cross-terms, in [0.75CH3CONH2 + 0.25{f KSCN + (1 - f )NaSCN}] system. The first moment (M1) of the intermolecular/interionic vibrational band in these DES systems is much higher than that in typical neutral molecular liquids and shows a weak but contrasting dependence on the bulk parameter sqrt {γ /ρ }. The time constants for picosecond overdamped Kerr transients in both the DES systems, which are obtained on the basis of the analysis fitted by a triexponential function, are rather insensitive to f for both the DES systems, but all the three time constants (fast: ˜1-3 ps; intermediate: ˜7-20 ps; and

  7. Continued investigations of the occurrence of water in Pahute Mesa emplacement holes

    SciTech Connect

    Hershey, R.L.; Brikowski, T.H.

    1995-04-01

    Periodically, water has been observed in emplacement boreholes drilled for underground testing of nuclear weapons at Pahute Mesa, Nevada Test Site, and is often at levels elevated above the predicted local water table. Water which may provide a means to transport residual radionuclides away from weapon tests may originate as fluids introduced during drilling, from naturally perched groundwater draining into the borehole, or from penetration of the local groundwater table. Lithium-bromide (Li-Br) tracer is being used to evaluate both the origin and movement of these borehole waters. The drilling fluid used to drill the final 100 meters of borehole U-19bh was chemically labeled with LiBr tracer. Lack of significant increase in borehole Br inventory over time indicates that standing water in U-9bh is not returned drilling fluid. Possible sources for the standing water are drilling fluid infiltrated above the bottom 100 in or natural water from a perched or shallower-than-expected saturated zone. The minimum detectable Darcy velocity of water passing through U-19bh is 0.3 m/yr. Borehole U-19bk has a water level approximately 50 in above the predicted pre-drilling water level. Initial water samples were collected from U-19bk to characterize the borehole water quality prior to adding the tracer. The major-ion analytical results of U-19bk along with historical water quality analyses of Water Well 20 and water well UE-19c show that all three waters are similar in character and therefore the water in U-19bk may be either residual drilling fluids originating from Water Well 20 and UE-19c or naturally occurring Pahute Mesa groundwater. LiBr tracer was added to the U-19bk borehole and samples for tracer analysis were collected one month later. For the one month period, no detectable loss of Br was observed. Over this short time period, the minimum detectable Darcy velocity is 10.6 m/yr.

  8. Ostéchondromatose synoviale de l'articulation carpo-métacarpienne du pouce chez une patiente atteinte d'un lupus érythémateux systémique

    PubMed Central

    Loukil, Hanen; Frikha, Faten; Snoussi, Mouna; Garbaa, Saida; Salah, Raida Ben; Bahloul, Zouhir

    2015-01-01

    L'ostéchondromatose synoviale est une métaplasie du tissu synovial. Elle engendre de petites masses cartilagineuses qui font saillie à la face interne de la synoviale, puis, se pédiculisent et enfin s'en détachent en développant des chondromes libres. On en distingue deux formes d'ostéchondromatose, la forme primitive, qui est rare, et la forme secondaire plus fréquente dont l'origine est généralement l'arthrose. Nous rapportons un cas d'ostéchondromatose synoviale de l'articulation carpo-métacarpienne du pouce chez une patiente atteinte d'un lupus érythémateux systémique. PMID:26918080

  9. Political Economy, the Internet and FL/OSS Development

    NASA Astrophysics Data System (ADS)

    Mansell, Robin; Berdou, Evangelia

    Despite the growing amount of research on Free/Libre/Open Source Software (FL/OSS) development, there is little insight into how structural factors associated with institutions influence the patterns of software developer activity in this area. This article examines some of the dynamics of the development of this type of software and the extent to which these dynamics are associated with features of the gift economy as is frequently suggested in the literature. Drawing on an empirical analysis of contributors to the GNOME FL/OSS project, we suggest that greater attention should be given to the emergence of a mixed economy in which features of the exchange economy come to the fore with implications for the power relationships among those contributing to FL/OSS.

  10. Hemispherand-Strapped Calix[4]pyrrole: An Ion-pair Receptor for the Recognition and Extraction of Lithium Nitrite.

    PubMed

    He, Qing; Zhang, Zhan; Brewster, James T; Lynch, Vincent M; Kim, Sung Kuk; Sessler, Jonathan L

    2016-08-10

    The hemispherand-strapped calix[4]pyrrole (1) acts as an ion pair receptor that exhibits selectivity for lithium salts. In organic media (CD2Cl2 and CD3OD, v/v, 9:1), receptor 1 binds LiCl with high preference relative to NaCl, KCl, and RbCl. DFT calculations provided support for the observed selectivity. Single crystal structures of five different lithium ion-pair complexes of 1 were obtained. In the case of LiCl, a single bridging water molecule between the lithium cation and chloride anion was observed, while tight contact ion pairs were observed in the case of the LiBr, LiI, LiNO3, and LiNO2 salts. Receptor 1 proved effective as an extractant for LiNO2 under both model solid-liquid and liquid-liquid extraction conditions. PMID:27442768

  11. Development of rechargeable lithium-bromine batteries with lithium ion conducting solid electrolyte

    NASA Astrophysics Data System (ADS)

    Takemoto, Koshin; Yamada, Hirotoshi

    2015-05-01

    Electrochemical performances of a prototype lithium-bromine battery (LBB) employing a solid electrolyte is investigated. The discharge capacity decreases with repeating charge/discharge cycles. Electrochemical impedance analysis reveals that the capacity fading is mainly due to increase in the interfacial resistance between an aqueous active material solution and a solid electrolyte. Based on the results of symmetric cells and structural analysis of the surface of the solid electrolyte immersed in Br2 solutions, it is suggested that a Li+-depletion layer is formed on the surface of the solid electrolyte as a result of contact with bromine. Addition of tetraethylammonium bromide (TEABr) depresses the interfacial resistance, which results in improved cycleability. LBB with 1.0 M LiBr and 0.25 M TEABr shows discharge capacity of 139 mAh/g-LiBr and Coulombic efficiency of 99.6% at 5th cycle.

  12. Fundamental Study of Absorption Cycle without Electric Solution Pump

    NASA Astrophysics Data System (ADS)

    Tsujimori, Atsushi; Sato, Kazuo; Nakao, Kazushige; Ohgushi, Tetsuro; Katsuta, Masafumi

    The absorption refrigerant cycle has been used in Japan, as energy shortage problem is more and more serious and environmental protection is of increasing importance. This type of air conditioner and chiller consume less electric power input than the electric one. However, the absorption refrigerator of large cooling capacity consumes some electric power with the required facility. Then in this research, the absorption cycle without the electric solution pump is proposed using a capillary pump and the possibility of making this cycle running using LiBr solution as a working fluid is investigated. As a result, it was found that the absorption cycle could be reached using a capillary wick in the generator to circulate the refrigerant and kept the strong and weak solution low pressure.

  13. Estudio de los Efectos Gravitomagnéticos en Cuerpos Masivos Rotantes

    NASA Astrophysics Data System (ADS)

    Velandia Heredia, N.; Tejeiro, J. M.

    2008-03-01

    A partir del estudio de los Efectos Gravitomagnéticos en cuerpos masivos rotantes, planteamos la expresión para medir el desfase en el tiempo, para diferentes observadores, que se dan cuando viajan dos rayos de luz por una guía de onda o de manera libre (geodésicas), en el plano azimutal y en el plano polar. Con lo anterior queremos abordar el experimento tipo Michelson y Morley, de forma que podamos involucrar el valor de la densidad del momento angular (a) en el retraso temporal para los dos haces de luz que viajan por los brazos del interferómetro, cuando este último es ubicado en el plano ecuatorial.

  14. Teaching Astronomy in non-formal education: stars workshop

    NASA Astrophysics Data System (ADS)

    Hernán-Obispo, M.; Crespo-Chacón, I.; Gálvez, M. C.; López-Santiago, J.

    One of the fields in which teaching Astronomy is more demanded is non-formal education. The Stars Workshop we present in this contribution consisted on an introduction to Astronomy and observation methods. The main objectives were: to know the main components of the Universe, their characteristics and the scales of size and time existing between them; to understand the movement of the different celestial objects; to know the different observational techniques; to value the different historical explanations about the Earth and the position of Humanity in the Universe. This Stars Workshop was a collaboration with the Escuela de Tiempo Libre Jumavi, which is a school dedicated to the training and non-formal education in the leisure field.

  15. Hydrophobication and characterisation of O-acetyl-galactoglucomannan for papermaking and barrier applications.

    PubMed

    Kisonen, Victor; Eklund, Patrik; Auer, Markku; Sjöholm, Rainer; Pranovich, Andrey; Hemming, Jarl; Sundberg, Anna; Aseyev, Vladimir; Willför, Stefan

    2012-05-01

    Norway spruce O-acetyl-galactoglucomannans (GGM) are water-soluble hemicelluloses that have potential to be produced in large scale as a side product of the mechanical pulping industry or by hot-water extraction of wood. Chemical modification is often needed to tailor such water-soluble polysaccharides into industrially valuable compounds. In this work, treatment of GGM with butyric and benzoic anhydride in pyridine/dimethylformamide rendered GGM derivatives, which were hydrophobic and partially soluble in organic solvents. The degree of substitution can be adjusted by varying the quantity of the reagent and reaction temperature. The dn/dc value for the benzoyl ester of GGM was determined in 0.05 M LiBr DMSO in order to obtain accurate molar mass analysis with SEC-MALLS-RI. Novel substances with adjusted hydrophobicity can thus be prepared on one step synthesis from natural hemicelluloses, which then showed a slight increase in the molar mass upon esterification. PMID:22370176

  16. Glyme-lithium salt phase behavior.

    PubMed

    Henderson, Wesley A

    2006-07-01

    Phase diagrams are reported for glyme mixtures with simple lithium salts. The glymes studied include monoglyme (DME), diglyme, triglyme, and tetraglyme. The lithium salts include LiBETI, LiAsF6, LiI, LiClO4, LiBF4, LiCF3SO3, LiBr, LiNO3, and LiCF3CO2. The phase diagrams clearly illustrate how solvate formation and thermophysical properties are dictated by the ionic association strength of the salt (i.e., the properties of the anions) and chain length of the solvating molecules. This information provides critical predictive capabilities for solvate formation and ionic interactions common in organometallic reagents and battery electrolytes. PMID:16805630

  17. Abort Options for Human Lunar Missions between Earth Orbit and Lunar Vicinity

    NASA Technical Reports Server (NTRS)

    Condon, Gerald L.; Senent, Juan S.; Llama, Eduardo Garcia

    2005-01-01

    Apollo mission design emphasized operational flexibility that supported premature return to Earth. However, that design was tailored to use expendable hardware for short expeditions to low-latitude sites and cannot be applied directly to an evolutionary program requiring long stay times at arbitrary sites. This work establishes abort performanc e requirements for representative onorbit phases of missions involvin g rendezvous in lunar-orbit, lunar-surface and at the Earth-Moon libr ation point. This study submits reference abort delta-V requirements and other Earth return data (e.g., entry speed, flight path angle) and also examines the effect of abort performance requirements on propul sive capability for selected vehicle configurations.

  18. [Health and primary education in the regenerationist ideology at the open educational institution].

    PubMed

    Ballester, R; Perdiguero, E

    1998-01-01

    The objective of this work is to reconstruct the discourse of the authors who published about issues establishing links between health and primary education in the Boletin de la Institucion Libre de Ensenanza at the time of the Spanish colonial crisis in 1898. This source has been chosen due to its relevance to Spanish pedagogical renovation. Physical education was taken as a model for analysis for two reasons: firstly, it is the aspect that received the most attention; secondly, it became the engine for change in the renovation programme. In addition, its holistic nature was intended to lead to the new citizen that was needed by the country after the loss of the colonies. PMID:11620570

  19. From university research to commercial product (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mathuis, Philip

    2016-03-01

    Ovizio Imaging Systems, a quantitative microscopic imaging spin-off of the Université Libre de Bruxelles, Belgium, was founded in the beginning of 2010 by Philip Mathuis, Serge Jooris, Prof. Frank Dubois and Dr. Catherine Yourassowky. The company has launched a range of specialized microscopy instruments for quantitative imaging mainly focused on the bioprocessing and diagnostics fields within the life sciences market. During my talk I will present the story of how an idea, emerged from the research labs of the University made it to a manufactured and sold product. The talk will look at many aspects of entrepreneurship and setting up a company, finding the funding for the project, attracting people, industrialization and product design and commercialization. It will also be focused on choices one has to make during the start-up phase and methodologies that can be applied in many different settings.

  20. Performance Analysis of XCPC Powered Solar Cooling Demonstration Project

    NASA Astrophysics Data System (ADS)

    Widyolar, Bennett K.

    A solar thermal cooling system using novel non-tracking External Compound Parabolic Concentrators (XCPC) has been built at the University of California, Merced and operated for two cooling seasons. Its performance in providing power for space cooling has been analyzed. This solar cooling system is comprised of 53.3 m2 of XCPC trough collectors which are used to power a 23 kW double effect (LiBr) absorption chiller. This is the first system that combines both XCPC and absorption chilling technologies. Performance of the system was measured in both sunny and cloudy conditions, with both clean and dirty collectors. It was found that these collectors are well suited at providing thermal power to drive absorption cooling systems and that both the coinciding of available thermal power with cooling demand and the simplicity of the XCPC collectors compared to other solar thermal collectors makes them a highly attractive candidate for cooling projects.

  1. Atomsk: A tool for manipulating and converting atomic data files

    NASA Astrophysics Data System (ADS)

    Hirel, Pierre

    2015-12-01

    We present a libre, Open Source command-line program named Atomsk, that aims at creating and manipulating atomic systems for the purposes of ab initio calculations, classical atomistic calculations, and visualization, in the areas of computational physics and chemistry. The program can run on GNU/Linux, Apple Mac OS X, and Microsoft Windows platforms. Many file formats are supported, allowing for easy conversion of atomic configuration files. The command-line options allow to construct supercells, insert point defects (vacancies, interstitials), line defects (dislocations, cracks), plane defects (stacking faults), as well as other transformations. Several options can be applied consecutively, allowing for a comprehensive workflow from a unit cell to the final atomic system. Some modes allow to construct complex structures, or to perform specific analysis of atomic systems.

  2. Performance of thermal-sprayed zinc anodes treated with humectants in cathodic protection systems

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Russell, James H.; Bennett, John E.; Milius, John K.; Cryer, Curtis B.; Soltesz, Steven M.

    2001-01-01

    Thermal-sprayed Zn anodes are used for impressed current cathodic protection (ICCP) systems in Oregon's reinforced concrete coastal bridges to minimize corrosion damage. Thermal-sprayed Zn performs well as an ICCP anode but the voltage requirement can increase with increasing electrochemical age. It also performs well as a galvanic (GCP) anode but current output can decrease with increasing electrochemical age. Past research has shown that increasing moisture at the Zn anode-concrete interface improves the operation of the thermal-sprayed Zn anode. Humectants, hygroscopic materials that are applied to the surface of the Zn-anode, can increase the moisture at the zinc-concrete interface, thereby improving the performance and extending the anode service life. Results are given for humectant-treated (LiBr and LiNO3) thermal-sprayed Zn anodes used in the laboratory electrochemical aging studies and in field studies on the Yaquina Bay Bridge, Oregon, USA.

  3. Les vies de Galilée

    SciTech Connect

    2009-11-26

    Qu'est-ce que l'astronomie? A quoi sert-elle ? Qui était Galilée ? Une soirée avec Fiami, auteur et dessinateur autour des vies de Galilée, titre de son nouvel ouvrage. Galilée y joue le protagoniste ou le complice de grandes découvertes à différentes époques et sous divers profils : Galilée à Babylone (-568) | Galilée à Alexandrie (-197) | Galilée en Inde (499) | Galilée à Venise (1609) | Galilée et Halley (1705) | Galilée revient (2009) Dans le cadre de l'année mondiale de l'astronomie. » Tout public » Entrée libre » Réservation groupes au +41 (0)22 767 76 76

  4. The Andrea Levialdi Fellowship

    NASA Astrophysics Data System (ADS)

    Fieschi, Roberto

    My first encounter with Cuba dates back to winter 1967-1968 at the Cultural Congress of La Havana, a very large international event to promote greater understanding of the reality of the Cuban Revolution. In fact the person invited was my friend and colleague Andrea Levialdi (Andrea already knew Cuba and loved it) who, unable to participate, allowed me to go in her place. So I landed at the airport of the "first free country in Latin America" with the delegation of the Italian Communist Party. In Havana I met other Italian physicists whom I already knew, among them Bruno Vitale and Daniele Amati. They, like me, were embarrassed by the generous hospitality of `Havana Libre,' especially in a country which was going through such difficulties. Despite our best efforts we did not succeed in receiving a more modest welcome.

  5. Development of a solar powered residential air conditioner (General optimization)

    NASA Technical Reports Server (NTRS)

    Lowen, D. J.

    1976-01-01

    A commercially available 3-ton residential Lithium Bromide (LiBr) absorption air conditioner was modified for use with lower temperature solar heated water. The modification included removal of components such as the generator, concentration control chamber, liquid trap, and separator; and the addition of a Chrysler designed generator, an off-the-shelf LiBr-solution pump. The design goal of the modified unit was to operate with water as the heat-transfer fluid at a target temperature of 85 C (185 F), 29.4 C (85 F) cooling water inlet, producing 10.5 kW (3 tons) of cooling. Tests were performed on the system before and after modification to provide comparative data. At elevated temperatures (96 C, 205 F), the test results show that Lithium Bromide was carried into the condenser due to the extremely violent boiling and degraded the evaporator performance.

  6. Lithium halide monolayers: Structural, electronic and optical properties by first principles study

    NASA Astrophysics Data System (ADS)

    Safari, Mandana; Maskaneh, Pegah; Moghadam, Atousa Dashti; Jalilian, Jaafar

    2016-09-01

    Using first principle study, we investigate the structural, electronic and optical properties of lithium halide monolayers (LiF, LiCl, LiBr). In contrast to graphene and other graphene-like structures that form hexagonal rings in plane, these compounds can form and stabilize in cubic shape interestingly. The type of band structure in these insulators is identified as indirect type and ionic nature of their bonds are illustrated as well. The optical properties demonstrate extremely transparent feature for them as a result of wide band gap in the visible range; also their electron transitions are indicated for achieving a better vision on the absorption mechanism in these kinds of monolayers.

  7. Les vies de Galilée

    ScienceCinema

    None

    2011-10-06

    Qu'est-ce que l'astronomie? A quoi sert-elle ? Qui était Galilée ? Une soirée avec Fiami, auteur et dessinateur autour des vies de Galilée, titre de son nouvel ouvrage. Galilée y joue le protagoniste ou le complice de grandes découvertes à différentes époques et sous divers profils : Galilée à Babylone (-568) | Galilée à Alexandrie (-197) | Galilée en Inde (499) | Galilée à Venise (1609) | Galilée et Halley (1705) | Galilée revient (2009) Dans le cadre de l'année mondiale de l'astronomie. » Tout public » Entrée libre » Réservation groupes au +41 (0)22 767 76 76

  8. A computer simulation using spreadsheets for learning concept of steady-state equilibrium

    NASA Astrophysics Data System (ADS)

    Sharda, Vandana; Sastri, O. S. K. S.; Bhardwaj, Jyoti; Jha, Arbind K.

    2016-03-01

    In this paper, we present a simple spreadsheet based simulation activity that can be performed by students at the undergraduate level. This simulation is implemented in free open source software (FOSS) LibreOffice Calc, which is available for both Windows and Linux platform. This activity aims at building the probability distribution for the possible macro-states of a system. This has been achieved by randomly sampling the configuration space consisting of all the possible microstates and determining the corresponding macrostate for each of the samples, which is akin to Monte-Carlo simulation. This simulation could act as a very useful tool in engaging students for learning the concepts of microstates, macrostates and steady state equilibrium, once the ideas have been introduced in the classroom. Further, the effect of the number of particles on the quality of steady state equilibrium achieved demonstrates the idea of thermodynamic limit.

  9. Development of a double-effect air conditioner-heater (deach) phase 2. Final report, January 1989-December 1989

    SciTech Connect

    De Vuono, A.C.; Landstrom, D.K.; Osborne, R.L.; Christensen, R.N.; Flanigan, L.

    1992-12-01

    The report describes the results of Phase II of a multi-phase project to develop a high-efficiency, gas-fired, residential size air-conditioner/heater based on a double-effect, absorption cycle using LiBr and water as working fluids. The results discussed include experimental and analytical analysis of various options for key components and subsystems including absorber, direct expansion evaporator, solution heat exchangers and burner/generator subsystem. The thermodynamic model used to evaluate various system design tradeoffs is also discussed. The results of the Phase II effort provided the basis for full-scale, integrated breadboard testing to be conducted in Phase III of the project.

  10. Simple solution for a complex problem: proanthocyanidins, galloyl glucoses and ellagitannins fit on a single calibration curve in high performance-gel permeation chromatography.

    PubMed

    Stringano, Elisabetta; Gea, An; Salminen, Juha-Pekka; Mueller-Harvey, Irene

    2011-10-28

    This study was undertaken to explore gel permeation chromatography (GPC) for estimating molecular weights of proanthocyanidin fractions isolated from sainfoin (Onobrychis viciifolia). The results were compared with data obtained by thiolytic degradation of the same fractions. Polystyrene, polyethylene glycol and polymethyl methacrylate standards were not suitable for estimating the molecular weights of underivatized proanthocyanidins. Therefore, a novel HPLC-GPC method was developed based on two serially connected PolarGel-L columns using DMF that contained 5% water, 1% acetic acid and 0.15 M LiBr at 0.7 ml/min and 50 °C. This yielded a single calibration curve for galloyl glucoses (trigalloyl glucose, pentagalloyl glucose), ellagitannins (pedunculagin, vescalagin, punicalagin, oenothein B, gemin A), proanthocyanidins (procyanidin B2, cinnamtannin B1), and several other polyphenols (catechin, epicatechin gallate, epicallocatechin gallate, amentoflavone). These GPC predicted molecular weights represented a considerable advance over previously reported HPLC-GPC methods for underivatized proanthocyanidins. PMID:21930278

  11. A packed bed dehumidifier/regenerator for solar air conditioning with liquid desiccants

    NASA Astrophysics Data System (ADS)

    Factor, H. M.; Grossman, G.

    1980-01-01

    A packed column air-liquid contactor has been studied in application to air dehumidification and regeneration in solar air conditioning with liquid desiccants. A theoretical model has been developed to predict the performance of the device under various operating conditions. Computer simulations based on the model are presented which indicate the practical range of air to liquid flux ratios and associated changes in air humidity and desiccant concentration. An experimental apparatus has been constructed and experiments performed with Monoethylene Glycol (MEG) and Lithium Bromide as desiccants. MEG experiments have yielded inaccurate results and have pointed out some practical problems associated with the use of Glycols. LiBr experiments show very good agreement with the theoretical model. Preheating of the air is shown to greatly enhance desiccant regeneration. The packed column yields good results as a dehumidifier/regenerator, provided pressure drop can be reduced with the use of suitable packing.

  12. Subjeans Condensations due to a Thermal Instability

    NASA Astrophysics Data System (ADS)

    Opher, R.; Valio, A.

    1990-11-01

    RESUMEN. Las observaciones recientes muestran que las nubes moleculares no son homogeneas, sino que tienen condensaciones. Se observa que estas condensaciones estan libres gravitacionalmente. C6mo se forman estas condensaciones? Sugerimos explicar estas conden sac jones como debidas a que la inestabilidad termica ayuda a la gravedad. Se estudi6 una funci5n de enfriamiento por gramo de la forma general A p T , en donde p y T son la densidad y la temperatura. Estamos interesados en el valor maximo de para la cual el colapso ocurre. Se estudiaron varios mode- los. Nuestros resultados indican que los valores de comparables con aquellos sugeridos por la literatura (1 < son suficientes para provocar el colapso de masas inferiores a la masa de Jeans por medio de inestabilidad termica, ayudada por gravedad y asi se forman las condensaciones libres gravitacionalmente. ABSTRACT: Recent observations show that molecular clouds are not homogeneous, but clumpy. Some clumps are observed to be gravitationally unbound. How did these clumps then form? We suggest explaining these condensation as due to thermal instability aiding gravit y The cooling function per gram studied is of the general form A p T,where pand T are the density and temperature, respectively. We are interested in the maximum value of for which collapse still occurs. Various models are studied. Our results indicate that values comparable to those suggested in the literature (1 < %< 2) are sufficient to trigger the collapse of subjeans masses by thermal instability, when aided by gravity, and form the observed gravitationally unbound clumps. Keq o : HYDRODYNAMICS - INTERSTELLAR CLOUDS

  13. Application of Tracer-Injection Techniques to Demonstrate Surface-Water and Ground-Water Interactions Between an Alpine Stream and the North Star Mine, Upper Animas River Watershed, Southwestern Colorado

    USGS Publications Warehouse

    Wright, Winfield G.; Moore, Bryan

    2003-01-01

    Tracer-injection studies were done in Belcher Gulch in the upper Animas River watershed, southwestern Colorado, to determine whether the alpine stream infiltrates into underground mine workings of the North Star Mine and other nearby mines in the area. The tracer-injection studies were designed to determine if and where along Belcher Gulch the stream infiltrates into the mine. Four separate tracer-injec-tion tests were done using lithium bromide (LiBr), optical brightener dye, and sodium chloride (NaCl) as tracer solu-tions. Two of the tracers (LiBr and dye) were injected con-tinuously for 24 hours, one of the NaCl tracers was injected continuously for 12 hours, and one of the NaCl tracers was injected over a period of 1 hour. Concentration increases of tracer constituents were detected in water discharging from the North Star Mine, substantiating a surface-water and ground-water connection between Belcher Gulch and the North Star Mine. Different timing and magnitude of tracer breakthroughs indicated multiple flow paths with different residence times from the stream to the mine. The Pittsburgh and Sultan Mines were thought to physically connect to the North Star Mine, but tracer breakthroughs were inconclusive in water from these mines. From the tracer-injection tests and synoptic measure-ments of streamflow discharge, a conceptual model was devel-oped for surface-water and ground-water interactions between Belcher Gulch and the North Star Mine. This information, combined with previous surface geophysical surveys indicat-ing the presence of subsurface voids, may assist with decision-making process for preventing infiltration and for the remedia-tion of mine drainage from these mines.

  14. Modelisations des effets de surface sur les jets horizontaux subsoniques d'hydrogene et de methane

    NASA Astrophysics Data System (ADS)

    Gomez, Luis Fernando

    Le developpement des codes et de normes bases sur une methodologie scientifique requiert la capacite de predire l'etendue inflammable de deversements gazeux d'hydrogene sous differentes conditions. Des etudes anterieures ont deja etabli des modeles bases sur les lois de conservation de la mecanique des fluides basees sur des correlations experimentales qui permettent de predire la decroissance de la concentration et de la vitesse d'un gaz le long de l'axe d'un jet libre vertical. Cette etude s'interesse aux effets de proximite a une surface horizontale parallele sur un jet turbulent. Nous nous interessons a son impact sur l'etendue du champ de la concentration et sur l'enveloppe inflammable en particulier. Cette etude est comparative : l'hydrogene est compare au methane. Ceci permet de degager l'influence des effets de difference de la densite sur le comportement du jet, et de comparer le comportement de l'hydrogene aux correlations experimentales, qui ont ete essentiellement etablies pour le methane. Un modele decrivant l'evolution spatio-temporelle du champ de concentration du gaz dilue est propose, base sur la mecanique des fluides computationnelle. Cette approche permet de varier systematiquement les conditions aux frontieres (proximite du jet a la surface, par exemple) et de connaitre en detail les proprietes de l'ecoulement. Le modele est implemente dans le code de simulations par volumes finis de FLUENT. Les resultats des simulations sont compares avec les lois de similitudes decoulant de la theorie des jets d'ecoulements turbulents libres ainsi qu'avec les resultats experimentaux disponibles. L'effet de la difference des masses molaires des constituantes du jet et des constituantes du milieu de dispersion est egalement etudie dans le contexte du comportement d'echelle de la region developpee du jet.

  15. Effects of electrolyte salts on the performance of Li-O2 batteries

    SciTech Connect

    Nasybulin, Eduard N.; Xu, Wu; Engelhard, Mark H.; Nie, Zimin; Burton, Sarah D.; Cosimbescu, Lelia; Gross, Mark E.; Zhang, Jiguang

    2013-02-05

    It is well known that the stability of nonaqueous electrolyte is critical for the rechargeable Li-O2 batteries. Although stability of many solvents used in the electrolytes has been investigated, considerably less attention has been paid to the stability of electrolyte salt which is the second major component. Herein, we report the systematic investigation of the stability of seven common lithium salts in tetraglyme used as electrolytes for Li-O2 batteries. The discharge products of Li-O2 reaction were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy. The performance of Li-O2 batteries was strongly affected by the salt used in the electrolyte. Lithium tetrafluoroborate (LiBF4) and lithium bis(oxalato)borate (LiBOB) decompose and form LiF and lithium borates, respectively during the discharge of Li-O2 batteries. Several other salts, including lithium bis(trifluoromethane)sulfonamide (LiTFSI), lithium trifluoromethanesulfonate (LiTf), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4) , and lithium bromide (LiBr) led to the discharge products which mainly consisted of Li2O2 and only minor signs of decomposition of LiTFSI, LiTf, LPF6 and LiClO4 were detected. LiBr showed the best stability during the discharge process. As for the cycling performance, LiTf and LiTFSI were the best among the studied salts. In addition to the instability of lithium salts, decomposition of tetraglyme solvent was a more significant factor contributing to the limited cycling stability. Thus a more stable nonaqueous electrolyte including organic solvent and lithium salt still need to be further developed to reach a fully reversible Li-O2 battery.

  16. Super-Maxwellian helium evaporation from pure and salty water

    NASA Astrophysics Data System (ADS)

    Hahn, Christine; Kann, Zachary R.; Faust, Jennifer A.; Skinner, J. L.; Nathanson, Gilbert M.

    2016-01-01

    Helium atoms evaporate from pure water and salty solutions in super-Maxwellian speed distributions, as observed experimentally and modeled theoretically. The experiments are performed by monitoring the velocities of dissolved He atoms that evaporate from microjets of pure water at 252 K and 4-8.5 molal LiCl and LiBr at 232-252 K. The average He atom energies exceed the flux-weighted Maxwell-Boltzmann average of 2RT by 30% for pure water and 70% for 8.5m LiBr. Classical molecular dynamics simulations closely reproduce the observed speed distributions and provide microscopic insight into the forces that eject the He atoms from solution. Comparisons of the density profile and He kinetic energies across the water-vacuum interface indicate that the He atoms are accelerated by He-water collisions within the top 1-2 layers of the liquid. We also find that the average He atom kinetic energy scales with the free energy of solvation of this sparingly soluble gas. This free-energy difference reflects the steeply decreasing potential of mean force on the He atoms in the interfacial region, whose gradient is the repulsive force that tends to expel the atoms. The accompanying sharp decrease in water density suppresses the He-water collisions that would otherwise maintain a Maxwell-Boltzmann distribution, allowing the He atom to escape at high energies. Helium is especially affected by this reduction in collisions because its weak interactions make energy transfer inefficient.

  17. Introduzione al Laboratorio di Fisica

    NASA Astrophysics Data System (ADS)

    Ciullo, Giuseppe

    La Fisica (dal greco τὰ ϕυσικὰ: le cose naturali) si pone l'obiettivo di descrivere e prevedere il comportamento dei fenomeni naturali, nonché degli apparati e degli strumenti, che hanno reso e rendono la nostra vita più comoda ed efficiente. Tale obiettivo viene perseguito mediante un'attenta osservazione dei fenomeni, con una conseguente schematizzazione dell'osservazione, per fornire una conoscenza della realtà oggettiva, affidabile, verificabile e condivisibile.

  18. Observacion y anatisis de la varlacton de parametros geofisicos de un pozo ubicado en el piedemonte lIanero

    NASA Astrophysics Data System (ADS)

    Montano Mejia, Felix Humberto

    2001-12-01

    Este articulo presenta el desarrollo de instrumentacion especializada que se diseiio y se puso en funcionamiento con el fin de real izar la observacion y el anal isis de la variacion de parametres geofisicos de un pozo ubicado en el piedemonte llanero. La instrumentacion esta compuesta por una estacion remota para el registro multipararnetro y una estacion local en la cual se analizan los registros bajados de la estacion remota mediante la interrogacion periodica.

  19. Facteurs de risque de l'inobservance thérapeutique chez les patients schizophrènes: étude cas- témoins'

    PubMed Central

    Aarab, Chadya; Elghazouani, Fatima; Aalouane, Rachid; Rammouz, Ismail

    2015-01-01

    Les progrès réalisés dans le traitement de la schizophrénie n'ont jusqu'ici pas modifié de manière radicale l'importance de l'adhésion des patients à leur médication. L'objectif de ce travail est d'identifier les facteurs de risque de l'abandon du traitement sur un échantillon marocain de malades schizophrènes. C'est une étude transversale menée au centre psychiatrique universitaire de Fès sur une période de 4 mois. Les malades inclus présentaient une schizophrénie ou un trouble schizo-affectif, sélectionnés en deux groupes observant et non observant. L’évaluation de l'observance a été faite par un hétéro-questionnaire comprenant une liste de causes d'abandon du traitement avec des réponses par oui ou non et à l'aide de l’échelle MARS (Medication Adherence Rating Scale). Le traitement statistique des résultats a été réalisé par le logiciel Epi Info version 3.5.1. On a recruté 164 participants, 112 étaient des malades non observants à leur traitement (cas) et 52 patients bien observants (témoins). L’âge moyen est 31 ans, avec une prédominance masculine. Les facteurs de risque d'inobservance thérapeutique sont: l’âge jeune, le sexe masculin, le célibat, les troubles addictifs. Les principales raisons d'abandon du traitement sont le changement fréquent du médecin, le manque d'informations sur la maladie, un mauvais insight et les effets secondaires des antipsychotiques. Le groupe de schizophrènes non adhérents à leur traitement pharmacologique avait un score élevé à l’échelle MARS dans 80% cas. Ces résultats doivent être pris en considération par le personnel soignant pour optimiser l'observance thérapeutique chez les patients souffrant de schizophrénie. PMID:26161196

  20. The Endangered Arctic, the Arctic as Resource Frontier: Canadian News Media Narratives of Climate Change and the North.

    PubMed

    Stoddart, Mark C J; Smith, Jillian

    2016-08-01

    The Arctic is one of the most radically altered parts of the world due to climate change, with significant social and cultural impacts as a result. Using discourse network analysis and qualitative textual analysis of articles published in the Globe and Mail and National Post during the period 2006 to 2010, we identify and analyze key frames that interpret the implications of climate change on the Arctic. We examine Canadian national news media coverage to ask: How does the Arctic enter media coverage of climate change? Is there evidence of a climate justice discourse in relation to regional disparities in the risks and harms of climate change between northern and southern Canada? Climate change in the Arctic is often framed through the lens of Canadian national interests, which downplays climate-related social impacts that are already occurring at subnational political and geographical scales. L'Arctique est une des régions du monde la plus radicalement altérée par le changement climatique, menant comme résultat des importants changements sociaux et culturels. En utilisant l'analyse des réseaux de discours ainsi que l'analyse textuelle qualitative des articles publiés dans le Globe and Mail et le National Post de 2006 à 2010, nous identifions and analysons des cadres clés qui servent à interpréter les conséquences du changement climatique dans l'Arctique. Nous examinons la couverture des médias nationaux canadiens pour pouvoir demander : comment est-ce que l'Arctique s'insère dans la couverture médiatique du changement climatique? Est-ce qu'il y a de la preuve d'un discours de la justice climatique en relation des disparités régionales des risques et méfaits du changement climatique entre le Canada du nord et du sud? Le changement climatique dans l'Arctique est souvent encadré à travers le prisme des intérêts nationaux canadiens, ce qui minimise les impacts sociaux reliés au climat qui se produisent actuellement aux échelons sous

  1. Radio-chimiothérapie adjuvante des adénocarcinomes gastriques: à propos de 34 cas et d'une revue de la literature

    PubMed Central

    James, Laurianne; Dossou, Sepos; Bellfiq, Sarah; Irigo, Joëlle; Ogandaga, Etienne; Mouden, Karima; Loughmari, Saïda; Filali, Dounia; El Majjaoui, Sanaa; Kebdani, Tayeb; Ahid, Samir; Benjafaar, Nourredine

    2014-01-01

    Notre étude consistera en l’évaluation du pronostic des patients porteurs d'un adénocarcinome gastrique opérés et traités par radio-chimiothérapie adjuvante en technique conformationnelle. Entre Janvier 2007 et Décembre 2011, 34 patients ont reçu après une chirurgie radicale (R0 ou R1), un à trois cycles de 5-Fluoro-uracile associé à de l'Elvorine en adjuvant, suivi d'une radio-chimiothérapie selon le même protocole à la dose de 45Gy, puis de deux cycles de chimiothérapie à un mois d'intervalle après la radio-chimiothérapie concomitante. Dans le groupe d’étude, il y avait 34 patients d’âge médian 50 ans (47-58), avec un sexe ratio (H/F) de 2,4. Une chirurgie de type R1 a été réalisée dans 26,5% des cas, et 53% des patients étaient de stade III-IV. Le rapport nombres de ganglions positifs, sur nombre de ganglions prélevés étaient > 0,4 dans 26,5% des cas. Durant le traitement mené à terme, une neutropénie de grade III a été observée chez quatre patients, avec des troubles digestifs (nausées, vomissement, ou diarrhée) de grade I/II dans la majorité des cas. Après un suivi médian de 20 mois, 70,6% des patients étaient en survie sans rechute, et 29,4% ont présenté une récidive métastatique; la survie globale à 5 ans était de 35,4% et la survie sans progression de 58,7%. La radio-chimiothérapie concomitante postopératoire pourrait être un régime efficace et sûre chez les patients ayant bénéficié d'une gastrectomie à visée curative dans le cancer de l'estomac localement avancé. PMID:25709728

  2. Le goitre plongeant à Tlemcen dans l'ouest algérien: aspect clinique et thérapeutique de 1996-2014

    PubMed Central

    Mesli, Smain Nabil; Regagba, Derbali; Tidjane, Anisse; Bouallou, Fouad; Abi-Ayad, Chakib

    2015-01-01

    La définition du goitre plongeant, la plus couramment employée, est tout goitre ne siégeant pas dans la région cervicale en position opératoire. Le but d’évaluer sa prise en charge, en insistant plus particulièrement sur les examens préopératoires, les difficultés chirurgicales et les complications postopératoire. Etude rétrospective étalée sur 16 ans; portant sur 50 cas colligés au service de chirurgie viscérale du CHU Tlemcen. L'intervention a consisté en une thyroïdectomie totale par voie cervicale dans 94% des cas. Ont été notées essentiellement, les hématomes, des paralysies récurentiels et les hypoparathyroïdie. L’âge moyen est de 54,76 ±11,992 ans Le caractère plongeant du goitre à été retrouvé chez 52% (n = 26) par une échographie thyroïdienne. Le scanner cervico-thoracique était pratiqué chez 25 patients 50%. Il a permis de confirmer le caractère plongeant du goitre. Tous nos patients ont bénéficié eu un geste radicale (thyroïdectomie totale n = 45, 90%), alors que 5 patients (10%) ayant déjà ont eu un geste sur la thyroïde, ont subi une totalisation. L'examen histologique à confirmé la bénignité dans 48 cas 96%. Trois patients (6%) avaient une paralysie récurentielle transitoire et un cas (2%) de paralysie récurentielle persistante. L'hypoparathyroïdie transitoire était notée chez (14%). Les goitres plongeants représentent une éventualité assez fréquente. Souvent révélés à l'occasion d'un examen clinique. L'examen tomodensitométrique qui permet l'exploration des espaces peu accessibles à l'imagerie conventionnelle. L'imagerie par résonance magnétique nucléaire paraît constituer une technique d'avenir. PMID:26405494

  3. Les sarcomes des tissus mous: à propos de 33 cas

    PubMed Central

    Abdou, Jiddou; Elkabous, Mustapha; M'rabti, Hind; Errihani, Hassan

    2015-01-01

    L'objectif de cette étude est de rapporter les particularités épidémiologiques, cliniques, histologiques, thérapeutiques et évolutives des sarcomes des tissus mous à l'Institut National d'Oncologie et de définir les facteurs influençant la survie des patients. C'est une étude rétrospective de 33 cas de sarcome des tissus mous, colligés entre janvier 2008 et décembre 2010. Les critères d’éligibilité étaient un âge supérieur à 16 ans, une épreuve histologique d'un sarcome des tissus mous à l'exclusion des tumeurs stromales gastro-intestinales (GIST). Les items recueillis étaient: épidémiologiques, cliniques, histologiques, Radiologiques, et thérapeutiques. Des analyses univariées puis multivariées ont été réalisées à la recherche de facteurs influençant la survie à 2 ans. Il s'agit de 33 cas, 17 Hommes et 16 Femmes, l’âge moyen était de 43,21 ans (Extrêmes= 18-76 ans). La tumeur était localisée aux extrémités dans 24 cas (72,72%). Le type histologique prédominant était le Liposarcome dans 9 cas (27,27%). Le stade tumoral était localisé dans 25 cas (75,8%), métastatique dans 8 cas (24,2%). Vingt-cinq tumeurs ont été traitées chirurgicalement dont 21 cas (84%) de chirurgie conservatrice et 4 cas (16%) de chirurgie radicale. La radiothérapie a été réalisée chez 10 patients (30,3%). La chimiothérapie a été faite chez 20 patients. En analyse univariée les facteurs pronostiques étaient l’âge (p=0,03) et le stade tumoral (p=0,09). L’âge et le stade tumoral sont des facteurs pronostiques influençant la survie des sarcomes des tissus mous. PMID:27022434

  4. Late Miocene (Proto-Gulf) Extension and Magmatism on the Sonoran Margin

    NASA Astrophysics Data System (ADS)

    Gans, P.; MacMillan, I.; Roldan-Quintana, J.

    2003-12-01

    Constraints on the magnitude and character of late Miocene (Proto-Gulf) deformation on the Sonoran margin of the Gulf of California extensional province are key to understanding how and when Baja California was captured by the Pacific plate and how strain was partitioned during the early stages of this transtensional rift system. Our new geologic mapping in southwestern Sonora and 40Ar/39Ar dating of pre-, syn-, and post-tectonic volcanic units indicate that late Miocene deformation and volcanic activity were largely restricted to a NW-trending, 100-120 km wide belt adjacent to the coast. Inboard of this belt, NW-SE extension is mainly older (>15 Ma) and occurred in an intra-arc or back-arc setting. Proto-Gulf deformation within the coastal belt was profoundly transtensional, with NW-striking, dextral strike slip faults operating in concert with N-S and NNE-striking normal and oblique slip faults to produce an inferred NW or NNW tectonic transport direction. The total amount of late Miocene NW directed dextral shear within the coastal belt is still poorly constrained, but may exceed 100 km. The locus of deformation and volcanic activity migrated westward or northwestward within the Sonoran coastal belt. in the eastern portion (Sierra Libre and Sierra El Bacatete) major volcanic activity commenced at ˜13.0 Ma and peaked at 12.0 Ma, and major faulting and tilting is bracketed between 12.0 and 10.6 Ma. Further west in the Sierra El Aguaje/San Carlos region, major volcanic activity commenced at 11.5 Ma and peaked at 10.5 Ma, and most faulting and tilting is bracketed between 10.7 and 9.3 Ma. On the coastal mountains northwest of San Carlos, rift related faulting and tilting continued after 8.5 Ma. Voluminous late Miocene (13-8 Ma) volcanic rocks within the Sonoran coastal belt were erupted from numerous centers (e.g. Sierra Libre, Guaymas, Sierra El Aguaje). These thick volcanic sections are compositionally diverse (basalt to rhyolite, with abundant dacite and

  5. Heterogeneity of equilibrium molten globule state of cytochrome c induced by weak salt denaturants under physiological condition.

    PubMed

    Rahaman, Hamidur; Alam Khan, Md Khurshid; Hassan, Md Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

    2015-01-01

    While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N. PMID:25849212

  6. ALHAMBRA-survey: a new tool for photo-z calibrations in absence of spec-z information

    NASA Astrophysics Data System (ADS)

    Molino Benito, A.; Benitez Lozano, N.; The Alhambra-Team

    2013-05-01

    La estimación de los desplazamientos al rojo (redshift) de las galaxias, derivados mediante fotometría multi-banda, se conoce con el nombre de photometric redshifts (photo-z). Es bien sabido que la precisión alcanzable por estas técnicas puede verse incrementada si se dispone de una muestra espectroscópica de galaxias (cuyos redshifts (spec-z) sean conocidos) con la que re-calibrar los puntos cero fotométricos. (Coe et al. 2006, Ilbert et al. 2008, Molino et al. 2012 in prep). ALHAMBRA-survey, que es un cartografiado extragaláctico (de ˜4 grados cuadrados) dedicado a la realización de un estudio de la evolución de las propiedades y contenido del Universo (Moles et al. 2005, 2008), presenta solapamientos parciales con otros cartografiados espectroscópicos ya existentes con el objetivo de validar y mejorar la precisión de sus photo-z. Sin embargo, dada la variabilidad fotométrica entre sus campos, resulta ineficiente extrapolar las correcciones de punto cero, introduciendo sesgos de inhomogeneidad en la precisión de los resultados. En este trabajo se presenta una nueva metodología que permite mejorar la calibración de los puntos cero fotométricos mediante la utilización de la información estadística proporcionada por los propios photo-z. Mediante esta técnica resulta posible no sólo mejorar la precisión de las estimaciones sino, además, soslayar la necesidad de obtener grandes muestras espectroscópicas.

  7. [In Process Citation].

    PubMed

    Schnettler, Berta; Höger, Yesly; Orellana, Ligia; Sepúlveda, José; Salinas-Oñate, Natalia; Lobos, Germán; Grunert, Klaus G

    2016-01-01

    Objetivo: caracterizar tipologías de estudiantes universitarios según la percepción de los hábitos alimentarios de sus familias. Material y método: se aplicó un cuestionario a una muestra no probabilística de 372 estudiantes de ambos géneros de la Universidad de La Frontera, Chile. El instrumento incluyó: Cuestionario de Hábitos Alimentarios Familiares (FEHQ), Satisfaction with Life Scale (SWLS), Satisfaction with Food-related Life (SWFL) y la Escala de Recursos Familiares (FRS). Se consultó peso y estatura aproximada, así como variables sociodemográficas. Resultados: mediante análisis factorial exploratorio (AFE) se detectaron tres factores en el FEHQ: importancia de la alimentación para los miembros de la familia, cohesión en las comidas familiares y presión por comer. Mediante AFE se detectaron dos factores en la FRS: apoyo intangible y tangible. Mediante análisis factorial confirmatorio se validó la estructura del FEHQ y de la FRS con aceptables niveles de bondad de ajuste. Mediante análisis clúster se distinguieron cuatro tipologías que difirieron significativamente en las puntuaciones de los componentes del FEHQ y de la FRS, puntajes de la SWLS y SWFL, índice de masa corporal, género y nivel socioeconómico. Las tipologías con mayores puntuaciones en "cohesión en las comidas familiares" reportan mayor apoyo intangible de sus familias y superiores puntuaciones en la SWLS y SWFL. Conclusiones: los resultados muestran que la frecuencia y la importancia asignada a las comidas en familia se asocian positivamente con el apoyo familiar percibido, especialmente en recursos intangibles, así como también con la satisfacción global con la vida y en el dominio de la alimentación. PMID:27238812

  8. [In Process Citation].

    PubMed

    Valdivielso Cortázar, E; Prieto Martínez, C; Fernández-Urién Sainz, I; Vila Costas, J J; Jiménez Pérez, F J; Guerra Lacunza, A

    2016-01-01

    La pancreatitis autoinmune (PAI) es una patología poco frecuente, aunque con una creciente incidencia en países orientales, si bien esto podría deberse a una mayor tasa de detección. Puede asociarse a otras patologías autoinmunes, y se ha descrito su asociación con la enfermedad sistémica por IgG4. La clínica es variada y el tratamiento habitualmente es médico, mediante corticoides.Se describe un caso clínico diagnosticado.Palabras clave. Pancreatitis autoinmune. IgG4. PMID:27125615

  9. Código árbol paralelizado para simulaciones astrofísicas. Experimentos de encuentros de galaxias compuestas

    NASA Astrophysics Data System (ADS)

    Viturro, H. R.; Carpintero, D. D.

    Se describe la implementación de un código árbol octal paralelizado desarrollado por los autores. Este código permite la integración del problema de N--cuerpos simultáneamente en varias computadoras (``cluster''), lo que permite desarrollar altas velocidades de cálculo. Se muestran los resultados de algunas integraciones de encuentros entre galaxias de disco con bulbo y halo, generadas mediante algoritmos no utilizados hasta el momento en este campo.

  10. Novel ternary molten salt electrolytes for intermediate-temperature sodium/nickel chloride batteries

    NASA Astrophysics Data System (ADS)

    Li, Guosheng; Lu, Xiaochuan; Coyle, Christopher A.; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.; Yang, Zhenguo

    2012-12-01

    The sodium-nickel chloride (ZEBRA) battery is operated at relatively high temperature (250-350 °C) to achieve adequate electrochemical performance. Reducing the operating temperature in the range of 150200 °C can not only lead to enhanced cycle life by suppressing temperature-related degradations, but also allow the use of lower cost materials for construction. To achieve adequate electrochemical performance at lower operating temperatures, reduction in ohmic losses is required, including the reduced ohmic resistance of β″-alumina solid electrolyte (BASE) and the incorporation of low melting point secondary electrolytes. In present work, planar-type Na/NiCl2 cells with a thin BASE (600 μm) and low melting point secondary electrolyte were evaluated at reduced temperatures. Molten salts used as secondary electrolytes were fabricated by the partial replacement of NaCl in the standard secondary electrolyte (NaAlCl4) with other lower melting point alkali metal salts such as NaBr, LiCl, and LiBr. Electrochemical characterization of these ternary molten salts demonstrated improved ionic conductivity and sufficient electrochemical window at reduced temperatures. Furthermore, Na/NiCl2 cells with 50 mol% NaBr-containing secondary electrolyte exhibited reduced polarizations at 175 °C compared to the cell with the standard NaAlCl4 catholyte. The cells also exhibited stable cycling performance even at 150 °C.

  11. La enumeración de la soltería femenina en los censos de población: sesgo y propuesta de corrección

    PubMed Central

    McCaa, Robert; Esteve, Albert; Garcia, Joan

    2013-01-01

    Esta investigación tiene como objetivo investigar el efecto que la disolución de las uniones consensuales tiene en los niveles de soltería que proporciona el Censo de Población, niveles derivados de la variable estado civil. Para ello comparamos los datos censales con los de la Encuestas de Demografía y Salud (de ahora en adelante DHS) en aquellos países y años para los que disponemos de ambas fuentes en el mismo año o años adyacentes (Bolivia, Brasil, Colombia y Perú). Los resultados muestran claramente que las proporciones de nunca unidas derivadas de la variable censal ’Estado civil’ son sistemáticamente más elevadas que las estimadas a partir de las DHS. La razón de esta sobreestimación obedece al hecho de que personas que estuvieron en unión libre en el pasado se declaran solteras en el momento del Censo. La elevada proporción de mujeres solteras que tienen hijos según el Censo es una prueba de ello y a su vez una solución efectiva para corregir el sesgo. PMID:25593515

  12. Open Source Approach to Urban Growth Simulation

    NASA Astrophysics Data System (ADS)

    Petrasova, A.; Petras, V.; Van Berkel, D.; Harmon, B. A.; Mitasova, H.; Meentemeyer, R. K.

    2016-06-01

    Spatial patterns of land use change due to urbanization and its impact on the landscape are the subject of ongoing research. Urban growth scenario simulation is a powerful tool for exploring these impacts and empowering planners to make informed decisions. We present FUTURES (FUTure Urban - Regional Environment Simulation) - a patch-based, stochastic, multi-level land change modeling framework as a case showing how what was once a closed and inaccessible model benefited from integration with open source GIS.We will describe our motivation for releasing this project as open source and the advantages of integrating it with GRASS GIS, a free, libre and open source GIS and research platform for the geospatial domain. GRASS GIS provides efficient libraries for FUTURES model development as well as standard GIS tools and graphical user interface for model users. Releasing FUTURES as a GRASS GIS add-on simplifies the distribution of FUTURES across all main operating systems and ensures the maintainability of our project in the future. We will describe FUTURES integration into GRASS GIS and demonstrate its usage on a case study in Asheville, North Carolina. The developed dataset and tutorial for this case study enable researchers to experiment with the model, explore its potential or even modify the model for their applications.

  13. Refinement of nano-structured fibroin thin films by near-IR pulsed laser deposition from targets consolidated with autogenous binder.

    PubMed

    Nakayama, S; Nozaki, R; Senna, M

    2008-01-01

    Silk fibroin (SF) powders were mixed with an autogenous binder from a natural cocoon after degumming with Na(2)CO(3) and liquefied with LiBr. An all-fibroin ablation target, SLT, obtained from the mixture after compression at ambient temperature, was compared with those without autogenous binder, SWT, or with a simple, non-autogenous binder, hydroxypropyl methylcellulose, SHT. The targets were then irradiated by a 1064 nm laser beam to obtain nano-structured thin films of fibroin by pulsed laser deposition (PLD) on Si (100). The properties of PLD films were examined mainly by atomic force microscope (AFM) or scanning electron microscope (SEM) for microstructures and morphology. By using an autogenous binder, significant increase was observed in the rate of nanofilm deposition with simultaneous decrease in the fraction of large debris. Size reduction of smallest protein units (SPUs) was also recognized by AFM. The autogenous binder turned out to be significantly superior over conventional, non-autogenous ones. PMID:18544238

  14. Hartree-Fock limit values of multipole moments, polarizabilities, and hyperpolarizabilities for atoms and diatomic molecules

    NASA Astrophysics Data System (ADS)

    Kobus, Jacek

    2015-02-01

    Recently it has been demonstrated that the finite difference Hartree-Fock method can be used to deliver highly accurate values of electric multipole moments together with polarizabilities αz z,Az ,z z , and hyperpolarizabilities βz z z, γz z z,Bz z ,z z , for the ground states of various atomic and diatomic systems. Since these results can be regarded as de facto Hartree-Fock limit values their quality is of the utmost importance. This paper reexamines the use of the finite field method to calculate these electric properties, discusses its accuracy, and presents an updated list of the properties for the following atoms and diatomic molecules: H-, He, Li, Li+,Li2 +,Li-,Be2 + , Be, B+,C2 + , Ne, Mg2 +, Mg, Al+,Si2 + , Ar, K+,Ca2 +,Rb+,Sr2 +,Zr4 +,He2 , Be2,N2,F2,O2 , HeNe, LiH2 +, LiCl, LiBr, BH, CO, FH, NaCl, and KF. The potential energy curves and the dependence of the electric properties on the internuclear distance is also studied for He2,LiH+,Be2 , and HeNe systems.

  15. Des proprietes de l'etat normal du modele de Hubbard bidimensionnel

    NASA Astrophysics Data System (ADS)

    Lemay, Francois

    Depuis leur decouverte, les etudes experimentales ont demontre que les supra-conducteurs a haute temperature ont une phase normale tres etrange. Les proprietes de ces materiaux ne sont pas bien decrites par la theorie du liquide de Fermi. Le modele de Hubbard bidimensionnel, bien qu'il ne soit pas encore resolu, est toujours considere comme un candidat pour expliquer la physique de ces composes. Dans cet ouvrage, nous mettons en evidence plusieurs proprietes electroniques du modele qui sont incompatibles avec l'existence de quasi-particules. Nous montrons notamment que la susceptibilite des electrons libres sur reseau contient des singularites logarithmiques qui influencent de facon determinante les proprietes de la self-energie a basse frequence. Ces singularites sont responsables de la destruction des quasi-particules. En l'absence de fluctuations antiferromagnetiques, elles sont aussi responsables de l'existence d'un petit pseudogap dans le poids spectral au niveau de Fermi. Les proprietes du modele sont egalement etudiees pour une surface de Fermi similaire a celle des supraconducteurs a haute temperature. Un parallele est etabli entre certaines caracteristiques du modele et celles de ces materiaux.

  16. Characterization of reactive tracers for C-wells field experiments 1: Electrostatic sorption mechanism, lithium

    SciTech Connect

    Fuentes, H.R.; Polzer, W.L.; Essington, E.H.; Newman, B.D.

    1989-11-01

    Lithium (Li{sup +}) was introduced as lithium bromide (LiBr), as a retarded tracer for experiments in the C-wells complex at Yucca Mountain, Nevada Test Site, Nevada. The objective was to evaluate the potential of lithium to sorb predominately by physical forces. lithium was selected as a candidate tracer on the basis of high solubility, good chemical and biological stability, and relatively low sorptivity; lack of bioaccumulation and exclusion as a priority pollutant in pertinent federal environmental regulations; good analytical detectability and low natural background concentrations; and a low cost Laboratory experiments were performed with suspensions of Prow Pass cuttings from drill hole UE-25p{number_sign}1 at depths between 549 and 594 m in J-13 water at a pH of approximately 8 and in the temperature range of 25{degree}C to 45{degree}C. Batch equilibrium and kinetics experiments were performed; estimated thermodynamic constants, relative behavior between adsorption and desorption, and potentiometric studies provided information to infer the physical nature of lithium sorption.

  17. Electrode-active material for electrochemical batteries and method of preparation

    SciTech Connect

    Varma, R.

    1987-08-18

    A method is described of preparing a battery electrode comprising providing an electrode-active material selected from chalogen-containing compounds of Ni, Fe, Pb, Co, Cu and mixtures thereof for a positive electrode and selected from the group consisting of Li, Na, K, Ca, Mg, Mn, Zn, Cd, Cu, Si, Al, Pb and alloys thereof for the negative electrode, mixing a ligand in the form of an electrically conductive polymer with the electrode-active material wherein the polymer is present in the range of from about 2% by weight to about 5% by weight of the electrode-active material, to provide metal ion or negative ion vacancies in the range of from about 0.05 to about 0.1 atom percent, the ligands for a positive electrode being selected from the class consisting of polyacetylene polymers having molecular weights in excess of 10,000 and cyclic polyamide with 3-5 functional groups. The ligands for a negative electrode are selected from the class consisting of tertiary butyl cyclohexyl-15-crown-5, TTF-TCNQ, and polymers of polyethylene oxide and one or more of LiCF/sub 3/SO/sub 3/, LiBr, Na/sub 2/S, and NaCN, mixing a binder with the electrode-active material and polymer, and forming the mixed electrode-active material and polymer and binder into a battery electrode.

  18. Effect of Forest Age on Rainwater Infiltration in the Lowland Humid Tropics

    NASA Astrophysics Data System (ADS)

    Kempema, E. W.; Mojica, A.; Litt, G.; Carey, A. M.; Ogden, F. L.

    2015-12-01

    We are working in the headwaters of the Rio Agua Salud catchment in central Panama to test the hypothesis that varying land uses, including time since afforestation, have significant impacts on rainfall infiltration, runoff generation and groundwater recharge. Increased infiltration and groundwater recharge during the wet season may result in increased groundwater flow during the dry season, the "sponge effect hypothesis". We irrigate a 6m by 2m test plot with slightly saline water at varying applied rainfall intensities using an ARS-type rainfall simulator, which has an oscillating boom mounted 2m above the forest floor, and four spray nozzles. We install 10cm tall lawn edging at the bottom of the test plot to direct surface water runoff to a small flume where runoff rates are recorded over time. In addition, we use time lapse ERI (electrical resistivity imaging) to map the vertical and downslope flow paths. We add NaCl to the applied water at a concentration of 200 mg/l, tagged with 10 mg/l LiBr as a salinity/conductivity contrast. Because ERI is highly sensitivity to changes in the electrical conductivity of soils and solute, we obtain a clear time-lapse image of flow path and bulk flow velocities. In this presentation we compare and contrast results of observations collected in an actively grazed cattle pasture adjacent ~10-12 year and >25 year old secondary forest plots using data collected during the 2015 wet season.

  19. Novel ternary molten salt electrolytes for intermediate-temperature sodium/nickel chloride batteries

    SciTech Connect

    Li, Guosheng; Lu, Xiaochuan; Coyle, Christopher A.; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.; Yang, Zhenguo

    2012-12-15

    The sodium–nickel chloride (ZEBRA) battery is operated at relatively high temperature (250–350 °C) to achieve adequate electrochemical performance. Reducing the operating temperature in the range of 150200 °C can not only lead to enhanced cycle life by suppressing temperature-related degradations, but also allow the use of lower cost materials for construction. To achieve adequate electrochemical performance at lower operating temperatures, reduction in ohmic losses is required, including the reduced ohmic resistance of β"-alumina solid electrolyte (BASE) and the incorporation of low melting point secondary electrolytes. In present work, planar-type Na/NiCl2 cells with a thin BASE (600 μm) and low melting point secondary electrolyte were evaluated at reduced temperatures. Molten salts used as secondary electrolytes were fabricated by the partial replacement of NaCl in the standard secondary electrolyte (NaAlCl4) with other lower melting point alkali metal salts such as NaBr, LiCl, and LiBr. Electrochemical characterization of these ternary molten salts demonstrated improved ionic conductivity and sufficient electrochemical window at reduced temperatures. Furthermore, Na/NiCl2 cells with 50 mol% NaBr-containing secondary electrolyte exhibited reduced polarizations at 175 °C compared to the cell with the standard NaAlCl4 catholyte. Finally, the cells also exhibited stable cycling performance even at 150 °C.

  20. HYBRIDCHECK: software for the rapid detection, visualization and dating of recombinant regions in genome sequence data.

    PubMed

    Ward, Ben J; van Oosterhout, Cock

    2016-03-01

    HYBRIDCHECK is a software package to visualize the recombination signal in large DNA sequence data set, and it can be used to analyse recombination, genetic introgression, hybridization and horizontal gene transfer. It can scan large (multiple kb) contigs and whole-genome sequences of three or more individuals. HYBRIDCHECK is written in the r software for OS X, Linux and Windows operating systems, and it has a simple graphical user interface. In addition, the r code can be readily incorporated in scripts and analysis pipelines. HYBRIDCHECK implements several ABBA-BABA tests and visualizes the effects of hybridization and the resulting mosaic-like genome structure in high-density graphics. The package also reports the following: (i) the breakpoint positions, (ii) the number of mutations in each introgressed block, (iii) the probability that the identified region is not caused by recombination and (iv) the estimated age of each recombination event. The divergence times between the donor and recombinant sequence are calculated using a JC, K80, F81, HKY or GTR correction, and the dating algorithm is exceedingly fast. By estimating the coalescence time of introgressed blocks, it is possible to distinguish between hybridization and incomplete lineage sorting. HYBRIDCHECK is libré software and it and its manual are free to download from http://ward9250.github.io/HybridCheck/. PMID:26394708

  1. Efficacité de la riboflavine dans la prévention de la migraine pédiatrique

    PubMed Central

    Sherwood, Michelle; Goldman, Ran D.

    2014-01-01

    Résumé Question Le taux des diagnostics de migraine chez les enfants est à la hausse. La riboflavine comme option de rechange aux agents pharmacologiques traditionnels est-elle efficace et sécuritaire pour la prévention de la migraine chez les enfants? Réponse Parce que la migraine est un problème très commun durant l’enfance et l’adolescence et contribue souvent à un fardeau considérable de la maladie, on s’intéresse de plus en plus à d’autres options que la prévention pharmacologique traditionnelle. On s’attendrait à ce que d’autres médicaments en vente libre soient moins toxiques, mieux tolérés et aient moins d’effets secondaires. Quelques études auprès d’adultes démontrent que la riboflavine (vitamine B2) pourrait diminuer la fréquence des migraines. Il est devenu une pratique habituelle de recommander que les enfants essaient la riboflavine pour prévenir la migraine; par ailleurs, la recherche sur l’utilisation de la riboflavine chez les enfants n’est pas concluante.

  2. Detection of urban O3, NO2, H2CO, and SO2 using Fourier transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Vandaele, Ann Carine; Carleer, M.; Colin, R.; Simon, Paul C.

    1993-02-01

    Concentrations of SO2, NO2, H2CO, and O3 have been measured regularly since October 1990 at the urban site of the Campus of the Universite Libre de Bruxelles, using the differential optical absorption spectroscopy (DOAS) technique associated with a Fourier Transform Spectrometer. The experimental set up has already been described elsewhere (Vandaele et al., 1992). It consists of a source (either a high pressure xenon lamp or a tungsten filament) and an 800 m long path system. The spectra are recorded in the 26,000 - 38,000 cm-1 and 14,000 - 30,000 cm-1 spectral regions, at the dispersion of 7.7 cm-1. The analytical method of the DOAS technique is based on the fact that in atmospheric measurements, it is impossible to obtain an experimental blank spectrum. Therefore, the Beer-Lambert law has to be rewritten as: I equals I'oen(Delta (sigma) d) where I is the measured intensity, Io the measured intensity from which all absorption structures have been removed, n the concentration, d the optical path length, and (Delta) (sigma) the differential absorption cross section of the molecule. Numerous methods for determining I'o exist. Fourier transform filtering has been used in this work. This method defines I'o as the inverse Fourier transform of the lower frequencies portion of the power spectrum of the experimental data. A least squares procedure is then applied in order to determine the concentration of the desired molecules.

  3. When Halides Come to Lithium Niobate Nanopowders Purity and Morphology Assistance.

    PubMed

    Lamouroux, Emmanuel; Badie, Laurent; Miska, Patrice; Fort, Yves

    2016-03-01

    The preparation of pure lithium niobate nanopowders was carried out by a matrix-mediated synthesis approach. Lithium hydroxide and niobium pentachloride were used as precursors. The influence of the chemical environment was studied by adding lithium halide (LiCl or LiBr). After thermal treatment of the precursor mixture at 550 °C for 30 min, the morphology of the products was obtained from transmission electron microscopy and dynamic light scattering, whereas the crystallinity and phase purity were characterized by X-ray diffraction and UV-visible and Raman spectroscopies. Our results point out that the chemical environment during lithium niobate formation at 550 °C influences the final morphology. Moreover, direct and indirect band-gap energies have been determined from UV-visible spectroscopy. Their values for the direct-band-gap energies range from 3.97 to 4.36 eV with a slight dependence on the Li/Nb ratio, whereas for the indirect-band-gap energies, the value appears to be independent of this ratio and is 3.64 eV. No dependence of the band-gap energies on the average crystallite and nanoparticle sizes is observed. PMID:26859157

  4. Enhancement in ionic conductivity on solid polymer electrolytes containing large conducting species

    NASA Astrophysics Data System (ADS)

    Praveen, D.; Damle, Ramakrishna

    2016-05-01

    Solid Polymer Electrolytes (SPEs) lack better conducting properties at ambient temperatures. Various methods to enhance their ionic conductivity like irradiation with swift heavy ions, γ-rays, swift electrons and quenching at low temperature etc., have been explored in the literature. Among these, one of the oldest methods is incorporation of different conducting species into the polymer matrix and/or addition of nano-sized inert particles into SPEs. Various new salts like LiBr, Mg(ClO4)2, NH4I etc., have already been tried in the past with some success. Also various nanoparticles like Al2O3, TiO2 etc., have been tried in the past. In this article, we have investigated an SPE containing Rubidium as a conducting species. Rubidium has a larger ionic size compared to lithium and sodium ions which have been investigated in the recent past. In the present article, we have investigated the conductivity of large sized conducting species and shown the enhancement in the ionic conductivity by addition of nano-sized inert particles.

  5. An Open Architecture for Distributed Malware Collection and Analysis

    NASA Astrophysics Data System (ADS)

    Cavalca, Davide; Goldoni, Emanuele

    Honeynets have become an important tool for researchers and network operators. However, the lack of a unified honeynet data model has impeded their effectiveness, resulting in multiple unrelated data sources, each with its own proprietary access method and format. Moreover, the deployment and management of a honeynet is a time-consuming activity and the interpretation of collected data is far from trivial. HIVE (Honeynet Infrastructure in Virtualized Environment) is a novel highly scalable automated data collection and analysis architecture we designed. Our infrastructure is based on top of proven FLOSS (Free, Libre and Open Source) solutions, which have been extended and integrated with new tools we developed. We use virtualization to ease honeypot management and deployment, combining both high-interaction and low-interaction sensors in a common infrastructure. We also address the need for rapid comprehension and detailed data analysis by harnessing the power of a relational database system, which provides centralized storage and access to the collected data while ensuring its constant integrity. This chapter presents our malware data collection architecture, offering some insight in the structure and benefits of a distributed virtualized honeynet and its development. Finally, we present some techniques for the active monitoring of centralized botnets we integrated in HIVE, which allow us to track the menaces evolution and timely deploy effective countermeasures.

  6. Gas-Microjet Reactive Scattering: Collisions of HCl and DCl with Cool Salty Water.

    PubMed

    Faust, Jennifer A; Sobyra, Thomas B; Nathanson, Gilbert M

    2016-02-18

    Liquid microjets provide a powerful means to investigate reactions of gases with salty water in vacuum while minimizing gas-vapor collisions. We use this technique to explore the fate of gaseous HCl and DCl molecules impinging on 8 molal LiCl and LiBr solutions at 238 K. The experiments reveal that HCl or DCl evaporate infrequently if they become thermally accommodated at the surface of either solution. In particular, we observe minimal thermal desorption of HCl following HCl collisions and no distinct evidence for rapid, interfacial DCl→HCl exchange following DCl collisions. These results imply that surface thermal motions are not generally strong enough to propel momentarily trapped HCl or DCl back into the gas phase before they ionize and disappear into solution. Instead, only HCl and DCl molecules that scatter directly from the surface escape entry. These recoiling molecules transfer less energy upon collision to LiBr/H2O than to LiCl/H2O, reflecting the heavier mass of Br(-) than of Cl(-) in the interfacial region. PMID:26828574

  7. Cycle Analysis using Exhaust Heat of SOFC and Turbine Combined Cycle by Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Takezawa, Shinya; Wakahara, Kenji; Araki, Takuto; Onda, Kazuo; Nagata, Susumu

    A power generating efficiency of solid oxide fuel cell (SOFC) and gas turbine combined cycle is fairly high. However, the exhaust gas temperature of the combined cycle is still high, about 300°C. So it should be recovered for energy saving, for example, by absorption chiller. The energy demand for refrigeration cooling is recently increasing year by year in Japan. Then, we propose here a cogeneration system by series connection of SOFC, gas turbine and LiBr absorption chiller to convert the exhaust heat to the cooling heat. As a result of cycle analysis of the combined system with 500kW class SOFC, the bottoming single-effect absorption chiller can produce the refrigerating capacity of about 120kW, and the double-effect absorption chiller can produce a little higher refrigerating capacity of about 130kW without any additional fuel. But the double-effect absorption chiller became more expensive and complex than the single-effect chiller.

  8. Development of Small Gas-fired Ammonia Absorption Air Conditioner for Residential Use

    NASA Astrophysics Data System (ADS)

    Sawada, Takashi; Yamamoto, Yoshiaki; Kobayashi, Hirotake; Shimaoka, Takaharu; Kawahara, Michinori; Uedono, Norio

    Due to the global environmental problems, the usage of natural refrigerants, such as water, ammonia, and hydrocarbons, are examined widely. Especially, absorption heat pump system using ammonia and water is penetrated widely for residential use in the U.S. and Europe, because it is easy to make the air-cooled system and to perform with high COP for heating. Authors have been developing an ammonia/water heat pump system for residential use. This system is driven by natural gas and supplies chilled water for cooling and hot water for heating. The results of performance tests indicated 6.8kW for cooling capacity and 10.3kW for heating capacity. And, some indexes which were related the charge of ammonium and the weight of the out-door unit, were compared with the same item of other equipments, such as, gas-fired LiBr absorption air-conditioners and gas engine driven heat pumps for residential use. The objective of this paper is to introduce the specifications and performance test results of the latest model, and to evaluate the performance of this heat pump system.

  9. Solar absorption cooling plant in Seville

    SciTech Connect

    Bermejo, Pablo; Pino, Francisco Javier; Rosa, Felipe

    2010-08-15

    A solar/gas cooling plant at the Engineering School of Seville (Spain) was tested during the period 2008-2009. The system is composed of a double-effect LiBr + water absorption chiller of 174 kW nominal cooling capacity, powered by: (1) a pressurized hot water flow delivered by mean of a 352 m{sup 2} solar field of a linear concentrating Fresnel collector and (2) a direct-fired natural gas burner. The objective of the project is to indentify design improvements for future plants and to serve as a guideline. We focused our attention on the solar collector size and dirtiness, climatology, piping heat losses, operation control and coupling between solar collector and chiller. The daily average Fresnel collector efficiency was 0.35 with a maximum of 0.4. The absorption chiller operated with a daily average coefficient of performance of 1.1-1.25, where the solar energy represented the 75% of generator's total heat input, and the solar cooling ratio (quotient between useful cooling and insolation incident on the solar field) was 0.44. (author)

  10. Crystallization Temperature of Aqueous Lithium Bromide Solutions at Low Evaporation Temperature

    SciTech Connect

    Kisari, Padmaja; Wang, Kai; Abdelaziz, Omar; Vineyard, Edward Allan

    2010-01-01

    Water- aqueous Lithium Bromide (LiBr) solutions have shown superior performance as working fluid pairs for absorption refrigeration cycles. Most of the available literature (e.g. ASHRAE Handbook of Fundamentals, etc.) provide crystallization behavior down to only 10 C. The typical evaporating temperature for an absorption chiller system is usually lower than 10 C. Hence, it is essential to have an accurate prediction of the crystallization temperature in this range in order to avoid crystallization during the design phase. We have therefore conducted a systematic study to explore the crystallization temperatures of LiBr/Water solutions that fall below an evaporating temperature of 10 C. Our preliminary studies revealed that the rate of cooling of the sample solution influences the crystallization temperature; therefore we have performed a quasi steady test where the sample was cooled gradually by reducing the sample temperature in small steps. Results from this study are reported in this paper and can be used to extend the data available in open literature.

  11. Compact heat and mass exchangers of the plate fin type in thermal sorption systems: Application in an absorption heat pump with the working pair CH3OH-LiBr/ZnBr2

    NASA Astrophysics Data System (ADS)

    Becker, Harry

    The possible application of Compact Heat and Mass Exchangers (CHME) in a gas fired Absorption Heat Pump (AHP) for domestic heating is studied. The above mentioned heat and mass exchangers are of the plate type. The space between the parallel and plain plates is filled up with corrugated plates of a certain height. The plain and finned plates are stacked and welded together. This gives a heat and mass exchanger which is very compact, expressed by a high area density (m2/m3). This leads to heat and mass transfer processes with small temperature and concentration differences. For testing purposes a pilot plant was built using the above type of components in order to test their heat and/or mass transfer performance. Only the generator is of the Shell And Tube (SAT) type. As the working pair, CH3OH - LiBr/ ZnBr2 was chosen, with the alcohol as the solvent and the salt mixture as the absorbent. This leads to sub atmospheric working pressures with only solvent in the vapor phase. Three series of experiments have been carried out, during which the input parameters were varied over a certain range. It is concluded that the plate fin CHMES are very suitable for application in an AHP for domestic heating purposes.

  12. Catalyst activation, deactivation, and degradation in palladium-mediated Negishi cross-coupling reactions.

    PubMed

    Böck, Katharina; Feil, Julia E; Karaghiosoff, Konstantin; Koszinowski, Konrad

    2015-03-27

    Pd-mediated Negishi cross-coupling reactions were studied by a combination of kinetic measurements, electrospray-ionization (ESI) mass spectrometry, (31)P NMR and UV/Vis spectroscopy. The kinetic measurements point to a rate-determining oxidative addition. Surprisingly, this step seems to involve not only the Pd catalyst and the aryl halide substrate, but also the organozinc reagent. In this context, the ESI-mass spectrometric observation of heterobimetallic Pd-Zn complexes [L2 PdZnR](+) (L=S-PHOS, R=Bu, Ph, Bn) is particularly revealing. The inferred presence of these and related neutral complexes with a direct Pd-Zn interaction in solution explains how the organozinc reagent can modulate the reactivity of the Pd catalyst. Previous theoretical calculations by González-Pérez et al. (Organometallics- 2012, 31, 2053) suggest that the complexation by the organozinc reagent lowers the activity of the Pd catalyst. Presumably, a similar effect also causes the rate decrease observed upon addition of ZnBr2 . In contrast, added LiBr apparently counteracts the formation of Pd-Zn complexes and restores the high activity of the Pd catalyst. At longer reaction times, deactivation processes due to degradation of the S-PHOS ligand and aggregation of the Pd catalyst come into play, thus further contributing to the appreciable complexity of the title reaction. PMID:25709062

  13. Molecular beam studies of HCl dissolution and dissociation in cold salty water.

    PubMed

    Brastad, Susan M; Nathanson, Gilbert M

    2011-05-14

    Gas-liquid scattering experiments are used to explore collisions and reactions of HCl and DCl with 12 mol% LiBr solutions of H(2)O and D(2)O at 208-218 K. These ∼6 M aqueous salt solutions have vapor pressures just below 0.01 Torr, requiring special consideration of the effects of gas-vapor collisions. We find that impinging HCl molecules readily equilibrate on the surface of the solution even at incident energies of 90 kJ mol(-1). Approximately 90% of the thermalized HCl molecules dissolve and dissociate for long times in the cold salty solution, while the remaining 10% desorb from the surface intact. There is no evidence for rapid, interfacial conversion of HCl into DCl, in striking contrast to previous observations of distinct submicrosecond DCl→HCl exchange in collisions of DCl with salty glycerol at 292 K. These results indicate that cold salty water efficiently captures impinging HCl molecules and suppresses interfacial proton exchange, most likely because of the long interaction times of the HCl molecules in contact with the cold surface and because of facile transport of H(+) and Cl(-) from the interfacial region into the bulk solution. PMID:21347480

  14. Ice VII from aqueous salt solutions: From a glass to a crystal with broken H-bonds.

    PubMed

    Klotz, S; Komatsu, K; Pietrucci, F; Kagi, H; Ludl, A-A; Machida, S; Hattori, T; Sano-Furukawa, A; Bove, L E

    2016-01-01

    It has been known for decades that certain aqueous salt solutions of LiCl and LiBr readily form glasses when cooled to below ≈160 K. This fact has recently been exploited to produce a « salty » high-pressure ice form: When the glass is compressed at low temperatures to pressures higher than 4 GPa and subsequently warmed, it crystallizes into ice VII with the ionic species trapped inside the ice lattice. Here we report the extreme limit of salt incorporation into ice VII, using high pressure neutron diffraction and molecular dynamics simulations. We show that high-pressure crystallisation of aqueous solutions of LiCl∙RH2O and LiBr∙RH2O with R = 5.6 leads to solids with strongly expanded volume, a destruction of the hydrogen-bond network with an isotropic distribution of water-dipole moments, as well as a crystal-to-amorphous transition on decompression. This highly unusual behaviour constitutes an interesting pathway from a glass to a crystal where translational periodicity is restored but the rotational degrees of freedom remaining completely random. PMID:27562476

  15. PLUME-FEATHER, Referencing and Finding Software for Research and Education

    NASA Astrophysics Data System (ADS)

    Bénassy, O.; Caron, C.; Ferret-Canape, C.; Cheylus, A.; Courcelle, E.; Dantec, C.; Dayre, P.; Dostes, T.; Durand, A.; Facq, A.; Gambini, G.; Geahchan, E.; Helft, C.; Hoffmann, D.; Ingarao, M.; Joly, P.; Kieffer, J.; Larré, J.-M.; Libes, M.; Morris, F.; Parmentier, H.; Pérochon, L.; Porte, O.; Romier, G.; Rousse, D.; Tournoy, R.; Valeins, H.

    2014-06-01

    PLUME-FEATHER is a non-profit project created to Promote economicaL, Useful and Maintained softwarEFor theHigher Education And THE Research communities. The site references software, mainly Free/Libre Open Source Software (FLOSS) from French universities and national research organisations, (CNRS, INRA...), laboratories or departments as well as other FLOSS software used and evaluated by users within these institutions. Each software is represented by a reference card, which describes origin, aim, installation, cost (if applicable) and user experience from the point of view of an academic user for academic users. Presently over 1000 programs are referenced on PLUME by more than 900 contributors. Although the server is maintained by a French institution, it is open to international contributions in the academic domain. All contained and validated contents are visible to anonymous public, whereas (presently more than 2000) registered users can contribute, starting with comments on single software reference cards up to help with the organisation and presentation of the referenced software products. The project has been presented to the HEP community in 2012 for the first time [1]. This is an update of the status and a call for (further) contributions.

  16. PLUME-FEATHER, Referencing and Finding Software for Research and Education

    NASA Astrophysics Data System (ADS)

    Hoffmann, Dirk; Romier, Geneviève

    2012-12-01

    PLUME-FEATHER is a non-profit project created to Promote economicaL, Useful and Maintained softwarE For the Higher Education And THE Research communities. The site references software, mainly Free/Libre Open Source Software (FLOSS) from French universities and national research organisations, (CNRS, INRA…), laboratories or departments as well as other FLOSS software used and evaluated by users within these institutions. Each software is represented by a reference card, which describes origin, aim, installation, cost (if applicable) and user experience from the point of view of an academic user for academic users. Presently over 1000 programs are referenced on PLUME. Although the server is maintained by a french institution, it is completely open to international contributions in the academic domainb. All contained and validated contents are visible to anonymous public, whereas registered users can contribute, starting with comments on single software reference cards up to help with the organisation and presentation of the referenced software products. This first presentation is call for (further) contributions from the HEP community.

  17. Economic feasibility and performance study of a solar-powered absorption cycle using some aqueous salt solutions

    SciTech Connect

    Malik, I.H.; Siddiqui, M.A.

    1997-02-01

    Economic analyses of solar collectors, for optimizing generator temperatures in the absorption cycle using aqueous solutions of LiBr, LiBr-ZnBr{sub 2}, LiBr-ZnBr{sub 2}-LiCl, and LiBr-ZnCl{sub 2}-CaBr{sub 2} salts, have been carried out for a wide range of the operating conditions. Ordinary collectors with two glass covers and evacuated-tubular collectors have been selected as the sources of energy for providing hot liquid in the generator of the absorption cycle. Of the four solutions, as the working fluids in the absorption cycles, those having better coefficients of performance are the LiBr/H{sub 2}O at the low evaporator temperatures, and the (LiBr-ZnBr{sub 2}-LiCl)/H{sub 2}O as well as the (LiBr-ZnCl{sub 2}-CaBr{sub 2})/H{sub 2}O at the high evaporator temperatures. Similarly, costs of the solar collectors are low, at low evaporation temperatures for the LiBr/H{sub 2}O and at high temperatures for the other two solutions: the (LiBr-ZnBr{sub 2})/H{sub 2}O, on the other hand, have relatively low COP and high operating costs.

  18. Abortion in Chile: the practice under a restrictive regime.

    PubMed

    Casas, Lidia; Vivaldi, Lieta

    2014-11-01

    This article examines, from a human rights perspective, the experience of women, and the practices of health care providers regarding abortion in Chile. Most abortions, as high as 100,000 a year, are obtained surreptitiously and clandestinely, and income and connections play a key role. The illegality of abortion correlates strongly with vulnerability, feelings of guilt and loneliness, fear of prosecution, physical and psychological harm, and social ostracism. Moreover, the absolute legal ban on abortion has a chilling effect on health care providers and endangers women's lives and health. Although misoprostol use has significantly helped to prevent greater harm and enhance women's agency, a ban on sales created a black market. Against this backdrop, feminists have taken action in aid of women. For instance, a feminist collective opened a telephone hotline, Linea Aborto Libre (Free Abortion Line), which has been crucial in informing women of the correct and safe use of misoprostol. Chile is at a crossroads. For the first time in 24 years, abortion law reform seems plausible, at least when the woman's life or health is at risk and in cases of rape and fetal anomalies incompatible with life. The political scenario is unfolding as we write. Congressional approval does not mean automatic enactment of a new law; a constitutional challenge is highly likely and will have to be overcome. PMID:25555764

  19. Numerical modeling of thermocapillary two-phase flows with evaporation using a two-scalar approach for heat transfer

    NASA Astrophysics Data System (ADS)

    Ma, C.; Bothe, D.

    2013-01-01

    A one-field model is derived from the sharp interface continuum mechanical balances for two-phase evaporative and thermocapillary flows. Emphasis is put on a clear distinction of the different velocities at the interface which appear due to phase transfer. The one-field model is solved numerically within a Finite Volume scheme and the interface is captured using an extended Volume of Fluid method, where the interface is reconstructed linearly with the PLIC technique. The numerical heat transfer is based on a two-scalar approach where two separate temperature fields are used for the temperature inside the two phases. This results in an accurate treatment of the interfacial heat transfer, specifically the interface temperature which is crucial numerically, both for evaporation and thermocapillarity. The method is validated for two-phase heat conduction, with analytical solution in case of no evaporation and with experimental measurement in case of incorporated evaporation effect. The method is applied to realistic cases dealing with non-uniformly heated thin liquid films, i.e. liquid films on (i) structured heated substrates and (ii) locally heated substrates. The numerical predictions in terms of flow pattern, surface deformation, temperature and velocity are compared with experiments conducted at the Université Libre de Bruxelles for (i) and at the Technische Universität Darmstadt for (ii). Qualitative agreement is achieved and shows the potential of this approach to simulate thermocapillary flows with dynamically deformable interfaces combined with evaporation.

  20. Bioclimatic profile and potential distribution of the Mesopotamian harvestman Discocyrtus testudineus (Holmberg, 1876) (Opiliones, Gonyleptidae).

    PubMed

    Acosta, Luis E

    2014-01-01

    The geographic range of the Neotropical harvestman Discocyrtus testudineus (Holmberg, 1876) (Gonyleptidae) is addressed by determining the species' bioclimatic profile and modeling its potential distribution. Analysis was performed on a record set of 71 localities, including literature records and 34 new localities reported here. The bioclimatic profile was characterized through extreme, median and dispersion features of the values of 19 bioclimatic variables across the record set. Predictive models were built with the presence-only methods MAXENT and, secondarily, BIOCLIM. Discocyrtus testudineus is a typical Mesopotamian harvestman, spreading across a wide region along the middle and lower Paraná River in subtropical / temperate Argentina, and extending, more or less continuously, up to the central province of Córdoba. Apparently diverging records (Paso de los Libres, on the Uruguay River, and Quilmes, on the southern coast of Rio de la Plata) proved to be predictable, even if suppressed from the dataset. Comparisons of cumulative frequencies curves and dispersion features (box-plots) were made with Discocyrtus dilatatus Sørensen, 1884 and Gryne orensis (Sørensen, 1884), other Mesopotamian species for which bioclimatic data are available. The relative importance of the bioclimatic variables used for modeling was also estimated. PMID:24989746

  1. The oxidative degradation of barley β-glucan in the presence of ascorbic acid or hydrogen peroxide.

    PubMed

    Mäkelä, Noora; Sontag-Strohm, Tuula; Maina, Ndegwa Henry

    2015-06-01

    Cereal β-glucans are polysaccharides with health benefits that have been linked to their ability to increase luminal viscosity. However, the functional properties of cereal β-glucans may be diminished by the susceptibility of this polysaccharide to oxidative degradation. In this study, barley β-glucan was oxidised with hydrogen peroxide or ascorbic acid and the oxidative degradation of β-glucan was investigated using both asymmetrical flow field-flow fractionation (AsFlFFF) with aqueous solvent and high performance size exclusion chromatography (HPSEC) with LiBr in DMSO as the solvent. Oxidation was shown to cause degradation of β-glucan, the reaction being faster when oxidised with hydrogen peroxide compared with ascorbic acid. Both HPSEC and AsFlFFF showed comparable results as long as aggregates (only observed in AsFlFFF) were not included in the integration. The compact aggregates observed in oxidised samples suggest oxidation driven interactions between β-glucan molecules. PMID:25843872

  2. All-Integrated Bifunctional Separator for Li Dendrite Detection via Novel Solution Synthesis of a Thermostable Polyimide Separator.

    PubMed

    Lin, Dingchang; Zhuo, Denys; Liu, Yayuan; Cui, Yi

    2016-08-31

    Safe operation is crucial for lithium (Li) batteries, and therefore, developing separators with dendrite-detection function is of great scientific and technological interest. However, challenges have been encountered when integrating the function into commercial polyolefin separators. Among all polymer candidates, polyimides (PIs) are prominent due to their good thermal/mechanical stability and electrolyte wettability. Nevertheless, it is still a challenge to efficiently synthesize PI separators, let alone integrate additional functions. In this work, a novel yet facile solution synthesis was developed to fabricate a nanoporous PI separator. Specifically, recyclable LiBr was utilized as the template for nanopores creation while the polymer was processed at the intermediate stage. This method proves not only to be a facile synthesis with basic lab facility but also to have promising potential for low-cost industrial production. The as-synthesized PI separator exhibited excellent thermal/mechanical stability and electrolyte wettability, the latter of which further improves the ionic conductivity and thus battery rate capability. Notably, stable full-cell cycling for over 200 cycles with a PI separator was further achieved. Based on this method, the fabrication of an all-integrated PI/Cu/PI bifunctional separator for dendrite detection can be fulfilled. The as-fabricated all-integrated separators prove efficient as early alarms of Li penetration, opening up the opportunity for safer battery design by separator engineering. PMID:27498838

  3. Investigations on the phase equilibria of some hydride ion conducting electrolyte systems and their application for hydrogen monitoring in sodium coolant

    NASA Astrophysics Data System (ADS)

    Joseph, Kitheri; Sujatha, K.; Nagaraj, S.; Mahendran, K. H.; Sridharan, R.; Periaswami, G.; Gnanasekaran, T.

    2005-09-01

    Electrochemical meters for measuring hydrogen levels in liquid sodium need thermodynamically stable hydride ion conducting electrolytes. In order to identify electrolytes that have high hydride ion conductivity, phase diagram of systems consisting of low melting compounds such as CaCl 2-LiCl, SrBr 2-LiBr, SrBr 2-SrHBr and CaBr 2-CaHBr were investigated by differential scanning calorimetry and their phase diagrams established. Using these information and supplementary information on effects of addition of alkaline earth hydride to these systems, potential electrolytes were tested for their use in electrochemical meters. Meters were constructed using electrolytes with (i) 22mol%SrCl 2-12.2mol%CaCl 2-54.5mol%LiCl-11.3mol%CaHCl, (ii) 70mol%LiCl-16mol%CaHCl-14mol%CaCl 2 and (iii) 40mol%CaHBr-60mol%CaBr 2 compositions. Output of meters that had Li ions in liquid phase electrolyte showed non-linearity at low hydrogen levels. Output of meters using CaBr 2-40mol%CaHBr solid showed linearity in the concentration range of 50-250 ppb in sodium.

  4. Oxidative properties and chemical stability of fluoronanotubes in matrixes of binary inorganic compounds.

    PubMed

    Peng, Haiqing; Gu, Zhenning; Liu, Yu; Chiang, Ivana W; Smalley, Richard E; Hauge, Robert H; Khabashesku, Valery N; Margrave, John L

    2003-01-01

    The chemical stability of fluoronanotubes in selected solid inorganic matrixes has been studied by initially mixing and mechanically grinding the components and subsequently heating them at temperatures ranging from 35 to 600 degrees C. The inorganic compounds selected for matrixes included halides (KBr, KI, Lil, LiBr, LiCl, NaCl, Znl2), oxides (Li2O, Fe2O3, PbO, MnO), lithium peroxide (Li2O2), potassium superoxide (KO2), sulfides (Li2S and ZnS), zinc selenide (ZnSe), lithium nitride (Li3N), and aluminum phosphide (AIP). Solid products, resulting from the proceeding chemical reactions, were analyzed by X-ray diffraction, Raman spectroscopy, and SEM/EDX elemental analysis. Gaseous and volatile products were identified with the help of the TGA/MS technique. Experimental data presented in this paper provide clear evidence that fluoronanotubes are not chemically inert toward the solid matrixes studied and exhibit significant oxidative properties in the redox reactions occurring under various temperatures, depending on the nature of the inorganic compound. PMID:12908234

  5. The GenABEL Project for statistical genomics

    PubMed Central

    Karssen, Lennart C.; van Duijn, Cornelia M.; Aulchenko, Yurii S.

    2016-01-01

    Development of free/libre open source software is usually done by a community of people with an interest in the tool. For scientific software, however, this is less often the case. Most scientific software is written by only a few authors, often a student working on a thesis. Once the paper describing the tool has been published, the tool is no longer developed further and is left to its own device. Here we describe the broad, multidisciplinary community we formed around a set of tools for statistical genomics. The GenABEL project for statistical omics actively promotes open interdisciplinary development of statistical methodology and its implementation in efficient and user-friendly software under an open source licence. The software tools developed withing the project collectively make up the GenABEL suite, which currently consists of eleven tools. The open framework of the project actively encourages involvement of the community in all stages, from formulation of methodological ideas to application of software to specific data sets. A web forum is used to channel user questions and discussions, further promoting the use of the GenABEL suite. Developer discussions take place on a dedicated mailing list, and development is further supported by robust development practices including use of public version control, code review and continuous integration. Use of this open science model attracts contributions from users and developers outside the “core team”, facilitating agile statistical omics methodology development and fast dissemination. PMID:27347381

  6. Cathodic Protection of the Yaquina Bay Bridge

    SciTech Connect

    Bullard, Sophie J.; Cramer, Stephen D.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Laylor, H.M.; Cryer, C.B.

    2001-02-01

    The Yaquina Bay Bridge in Newport, Oregon, was designed by Conde B. McCullough and built in 1936. The 3,223-foot (982 m) structure is a combination of concrete arch approach spans and a steel through arch over the shipping channel. Cathodic protection is used to prevent corrosion damage to the concrete arches. The Oregon Department of Transportation (Oregon DOT) installed a carbon anode coating (DAC-85) on two of the north approach spans in 1985. This anode was operated at a current density of 6.6 mA/m2(0.6 mA/ft2). No failure of the conductive anode was observed in 1990, five years after application, or in 2000, 15 years after application. Thermal-sprayed zinc anodes 20 mils (0.5 mm) thick were applied to half the south approach spans beginning in 1990. Thermal-sprayed zinc anodes 15 mils (0.4 mm) thick were applied to the remaining spans in 1996. These anodes were operated at a current density of 2.2 mA/m2(0.2 mA/ft2). In 1999, four zones on the approach spans were included in a two-year field trial of humectants to improve zinc anode performance. The humectants LiNO3 and LiBr were applied to two zones; the two adjacent zones were left untreated as controls. The humectants substantially reduced circuit resistance compared to the controls.

  7. Size exclusion chromatography for analyses of fibroin in silk: optimization of sampling and separation conditions

    NASA Astrophysics Data System (ADS)

    Pawcenis, Dominika; Koperska, Monika A.; Milczarek, Jakub M.; Łojewski, Tomasz; Łojewska, Joanna

    2014-02-01

    A direct goal of this paper was to improve the methods of sample preparation and separation for analyses of fibroin polypeptide with the use of size exclusion chromatography (SEC). The motivation for the study arises from our interest in natural polymers included in historic textile and paper artifacts, and is a logical response to the urgent need for developing rationale-based methods for materials conservation. The first step is to develop a reliable analytical tool which would give insight into fibroin structure and its changes caused by both natural and artificial ageing. To investigate the influence of preparation conditions, two sets of artificially aged samples were prepared (with and without NaCl in sample solution) and measured by the means of SEC with multi angle laser light scattering detector. It was shown that dialysis of fibroin dissolved in LiBr solution allows removal of the salt which destroys stacks chromatographic columns and prevents reproducible analyses. Salt rich (NaCl) water solutions of fibroin improved the quality of chromatograms.

  8. Ice VII from aqueous salt solutions: From a glass to a crystal with broken H-bonds

    PubMed Central

    Klotz, S.; Komatsu, K.; Pietrucci, F.; Kagi, H.; Ludl, A.-A.; Machida, S.; Hattori, T.; Sano-Furukawa, A.; Bove, L. E.

    2016-01-01

    It has been known for decades that certain aqueous salt solutions of LiCl and LiBr readily form glasses when cooled to below ≈160 K. This fact has recently been exploited to produce a « salty » high-pressure ice form: When the glass is compressed at low temperatures to pressures higher than 4 GPa and subsequently warmed, it crystallizes into ice VII with the ionic species trapped inside the ice lattice. Here we report the extreme limit of salt incorporation into ice VII, using high pressure neutron diffraction and molecular dynamics simulations. We show that high-pressure crystallisation of aqueous solutions of LiCl∙RH2O and LiBr∙RH2O with R = 5.6 leads to solids with strongly expanded volume, a destruction of the hydrogen-bond network with an isotropic distribution of water-dipole moments, as well as a crystal-to-amorphous transition on decompression. This highly unusual behaviour constitutes an interesting pathway from a glass to a crystal where translational periodicity is restored but the rotational degrees of freedom remaining completely random. PMID:27562476

  9. Monitoring of leachate at a test road using treated fly ash from municipal solid waste incinerator.

    PubMed

    François, D; Criado, C

    2007-01-31

    A treatment process for municipal solid waste incinerator fly ash has been jointly developed by the Université Libre in Brussels and the Solvay company. This experimental process has led to an experimental project with a multi-disciplinary team from Solvay along with several companies and organisations, plus support from the ADEME agency. After a laboratory assessment of the treated fly ash (TFA), its environmental properties and the optimal fields of application in road construction, as part of the Revasol project, a full-scale analysis was organised for both environmental and mechanical purposes. A test section using TFA was designed in order to collect percolation water; TFA was used as a road base component (a cement-bound graded aggregate containing 12% TFA). A reference section with the same structure was also built using natural materials. After a description of the treatment process and the test road design, the main TFA characteristics are presented. Then, the environmental behaviour of both sections over a 1-year period following construction is detailed: infiltration, leachate quality, cumulative release. This monitoring effort highlights not only the evolution in TFA behaviour, but also the general permeability of the road structure to various external influences. PMID:16621275

  10. Sequential automated fusion/extraction chromatography methodology for the dissolution of uranium in environmental samples for mass spectrometric determination.

    PubMed

    Milliard, Alex; Durand-Jézéquel, Myriam; Larivière, Dominic

    2011-01-17

    An improved methodology has been developed, based on dissolution by automated fusion followed by extraction chromatography for the detection and quantification of uranium in environmental matrices by mass spectrometry. A rapid fusion protocol (<8 min) was investigated for the complete dissolution of various samples. It could be preceded, if required, by an effective ashing procedure using the M4 fluxer and a newly designed platinum lid. Complete dissolution of the sample was observed and measured using standard reference materials (SRMs) and experimental data show no evidence of cross-contamination of crucibles when LiBO(2)/LiBr melts were used. The use of a M4 fusion unit also improved repeatability in sample preparation over muffle furnace fusion. Instrumental issues originating from the presence of high salt concentrations in the digestate after lithium metaborate fusion was also mitigated using an extraction chromatography (EXC) protocol aimed at removing lithium and interfering matrix constituants prior to the elution of uranium. The sequential methodology, which can be performed simultaneously on three samples, requires less than 20 min per sample for fusion and separation. It was successfully coupled to inductively coupled plasma mass spectrometry (ICP-MS) achieving detection limits below 100 pg kg(-1) for 5-300 mg of sample. PMID:21167982

  11. Effect of salts on the electrospinning of poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Stanger, Jonathan J.; Tucker, Nick; Staiger, Mark; Kirwan, Kerry; Coles, Stuart; Jacobs, Daniel; Larsen, Nigel

    2009-07-01

    Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept of a virtual orifice. The increase in the final fibre diameter is explained by considering the charge distribution in the jet when it behaves like a conductor compared to when it behaves like an insulator. Both mechanisms result from the increase in conductivity of the PVOH solution without significantly modifying other solution properties when salt is added.

  12. The Surface Structure of Concentrated Aqueous salt Solutions

    SciTech Connect

    Sloutskin,E.; Baumert, J.; Ocko, B.; Kuzmenko, I.; Checco, A.; Tamam, L.; Ofer, E.; Gog, T.; Deutsch, M.

    2007-01-01

    The surface-normal electron density profile {rho}{sub s}(z) of concentrated aqueous salt solutions of RbBr, CsCl, LiBr, RbCl, and SrCl{sub 2} was determined by x-ray reflectivity (XR). For all but RbBr and SrCl{sub 2} {rho}{sub s}(z) increases monotonically with depth z from {rho}{sub s}(z)=0 in the vapor (z<0) to {rho}{sub s}(z) = {rho}{sub b} of the bulk (z>0) over a width of a few angstroms. The width is commensurate with the expected interface broadening by thermally excited capillary waves. Anomalous (resonant) XR of RbBr reveals a depletion at the surface of Br{sup -} ions to a depth of {approx}10 A. For SrCl{sub 2}, the observed {rho}{sub s}(z)>{rho}{sub b} may imply a similar surface depletion of Cl{sup -} ions to a depth of a few angstroms. However, as the deviations of the XRs of RbBr and SrCl{sub 2} from those of the other solutions are small, the evidence for a different ion composition in the surface and the bulk is not strongly conclusive. Overall, these results contrast earlier theoretical and simulational results and nonstructural measurements, where significant surface layering of alternate, oppositely charged, ions is concluded.

  13. [Simon Morelot (1751-1809). A pharmacist out of the common].

    PubMed

    Flahaut, Jean

    2005-01-01

    He was born in a family of pharmacists of Beaune. He was a pharmacist in Paris, successively in four different places. He played an important part in the life of the Collège de pharmacie, which became in 1793 the Société libre des Pharmaciens de Paris. In the school of pharmacy, which was conducted by this Society, he had large charges in the administration and the teaching. With these offices, he was obliged to leave his pharmacy and to live in the school, Arbalètre street. In 1803, this school was replaced by a State school, and he was deprived of these functions. He joined in the armies of Napoléon, and successively was: a pharmacist of first class at Brest, a pharmacist in chief during the campaign of Prussia and Poland, and in the end major pharmacist in the army of Spain. He died in Cataluna in 1809, as a result of an "adynamic" fever. He wrote four important books, between 1800 and 1809, dedicated to pharmacy and to natural sciences, which gave a large view of the teaching he had previously made. PMID:17152869

  14. Kinetics and mechanism of monomolecular heterolysis of framework compounds. IV. Ionization of 1-adamantyl iodide in propylene carbonate

    SciTech Connect

    Ponomareva, E.A.; Tarasenko, P.V.; Yurchenko, A.G.; Dvorko, G.F.

    1987-09-10

    The heterolysis of 1-iodoadamantane in propylene carbonate was studied preparatively and kinetically; v = k (1-AdI), k/sub 25/ = 2.50 x 10/sup -8/ sec/sup -1/, ..delta..H/sup does not equal/ = 90.9 kJ/mole, ..delta..S/sup does not equal/ = -85.5 J/mole x deg. Additions of water, LiClO/sub 4/, and Et/sub 4/N/sup +/ClO/sub 4//sup -/ increase and additions of Et/sub 4/N/sup +/I/sup -/, LiBr, Et/sub 4/N/sup +/Br..sqrt.., Bu/sub 4/N/sup +/Br/sup -/, Et/sup 4/N/sup +/Cl/sup -/, LiPic, and Et/sub 4/N/sup +/Pic/sup -/ reduce the reaction rate. It is suggested that a sterically separated ion pair is formed in the rate-controlling stage and is quickly transformed into a solvent-separated ion pair, which then gives the reaction products. The negative salt effect is due to the action of the salt on the sterically separated ion pair.

  15. The IceCube Astrophysics Masterclass: Bringing Authentic Research to Teachers and Students

    NASA Astrophysics Data System (ADS)

    Madsen, J.; Bravo Gallart, S.; Demerit, J.; Madsen, M.

    2014-12-01

    The IceCube Astrophysics MasterClass (icecube.wisc.edu/masterclass) is based on the highly successful International masterclasses developed for high school students and teachers by the International Particle Physics Outreach Group (www.physicsmasterclasses.org/). The idea is to work with local teachers to identify highly motivated and engaged students who want to learn more about science research and the people who do it. An intensive one day program was put together at multiple sites with an opportunity for the students and teachers who attended to connect virtually to discuss their research results, and get a report from the winterovers at the South Pole. In the spring of 2014, the IceCube Collaboration held its first masterclass with approximately 100 students in total at 5 sites---Universität Mainz (Germany), University of Delaware in Newark (US), Université Libre de Bruxelles and Vrije Universiteit Brussels (Belgium), and the Wisconsin IceCube Particle Astrophysics Center at the University of Wisconsin-Madison (US). The students looked through IceCube data and performed analyses that led to the first evidence for high-energy astrophysical neutrinos. A description of the resources developed for the class, tactics used to recruit students and teachers, and the evaluation of the first course will be presented. The structure of the day can be readily generalized for other topics and disciplines.

  16. The GenABEL Project for statistical genomics.

    PubMed

    Karssen, Lennart C; van Duijn, Cornelia M; Aulchenko, Yurii S

    2016-01-01

    Development of free/libre open source software is usually done by a community of people with an interest in the tool. For scientific software, however, this is less often the case. Most scientific software is written by only a few authors, often a student working on a thesis. Once the paper describing the tool has been published, the tool is no longer developed further and is left to its own device. Here we describe the broad, multidisciplinary community we formed around a set of tools for statistical genomics. The GenABEL project for statistical omics actively promotes open interdisciplinary development of statistical methodology and its implementation in efficient and user-friendly software under an open source licence. The software tools developed withing the project collectively make up the GenABEL suite, which currently consists of eleven tools. The open framework of the project actively encourages involvement of the community in all stages, from formulation of methodological ideas to application of software to specific data sets. A web forum is used to channel user questions and discussions, further promoting the use of the GenABEL suite. Developer discussions take place on a dedicated mailing list, and development is further supported by robust development practices including use of public version control, code review and continuous integration. Use of this open science model attracts contributions from users and developers outside the "core team", facilitating agile statistical omics methodology development and fast dissemination. PMID:27347381

  17. Actividad funcional cerebral en estado de reposo: REDES EN CONEXIÓN

    PubMed Central

    Proal, Erika; Alvarez-Segura, Mar; de la Iglesia-Vayá, Maria; Martí-Bonmatí, Luis; Castellanos, F. Xavier

    2015-01-01

    Resumen El análisis de la conectividad funcional mediante resonancia magnética funcional (RMf) puede llevarse a cabo durante la realización de una tarea, la percepción de un estímulo o en estado de reposo. Estos análisis han demostrado su fiabilidad y reproducibilidad con diferentes enfoques (matemáticos, estadísticos, físicos) para seleccionar los vóxeles activados. El estudio de la señal de baja frecuencia en la actividad cerebral a través del contraste BOLD en estado de reposo ha revelado patrones de actividad cortical sincronizados, permitiendo describir la arquitectura funcional intrínseca del cerebro humano. La comunidad científica internacional dispone de recursos compartidos que contribuirán mediante este análisis de RMf en estado de reposo a la obtención de diagnósticos y tratamientos más precisos y avanzados en el campo de las neurociencias. PMID:21365601

  18. [Not Available].

    PubMed

    Fernández Castillo, Rafael; Cañadas de la Fuente, Gustavo R; Cañadas de la Fuente, Guillermo A; De la Fuente Solana, Emilia Inmaculada; Esteban de la Rosa, Rafael José; Bravo Soto, Juan

    2016-01-01

    Introducción: la obesidad y el sobrepeso presentan efectos adversos sobre la salud, lo que contribuye a la aparición de enfermedades metabólicas y cardiovasculares que ponen en peligro la integridad del injerto.Objetivo: investigar la influencia del IMC pretrasplante renal sobre el funcionamiento del injerto renal al año de trasplante mediante el estudio de cuatro métodos distintos de medir la filtración glomerular.Material y métodos: en este trabajo se ha seguido a 1.336 pacientes de ambos sexos trasplantados renales; se les realizaron mediciones pretrasplante y postrasplante de parámetros bioquímicos, mediciones antropométricas y función renal mediante medidas de filtrado glomerular.Resultados: a mayor índice de masa corporal pretrasplante se produce una disminución del filtrado glomerular medido por cuatro métodos distintos, así como mayor porcentaje de rechazos.Conclusiones: un IMC elevado pretrasplante contribuye a la disfunción del injerto, a una disminución del filtrado glomerular y a complicaciones del injerto en el primer año postrasplante. PMID:27571669

  19. Adenomyose utérine, étude clinique et thérapeutique: à propos de 87 cas

    PubMed Central

    Kdous, Moez; Ferchiou, Monia; Zhioua, Fethi

    2015-01-01

    Le but de notre étude est l'analyse des différents aspects épidémiologiques, cliniques, paracliniques et thérapeutiques de l'adénomyose. Il s'agit d'une étude rétrospective sur 87 patientes ayant bénéficié d'une hystérectomie pour des raisons diverses (hors prolapsus) entre le 1er janvier 2000 et 31 décembre 2006 et dont l’étude histologique de la pièce opératoire a révélé la présence d'adénomyose. 586 hystérectomies (hors prolapsus) ont été réalisées pendant la même période d’étude, soit une fréquence de l'adénomyose sur pièce opératoire de 14.85%. L'age moyen de nos patientes est de 43.97 ans (extrêmes: 26-64 ans). 29.88% d'entres-elles sont ménopausées et 41.37% avaient des antécédents de traumatisme utérin. La symptomatologie a été dominée par les ménometrorragies (82.77%) et les douleurs pelviennes (71.22%). Le diagnostic préopératoire a été suspecté sur les données de l'hystéroscopie dans 63.22% des cas, de l'hystérographie dans 58.46% des cas et de l’échographie transvaginale dans 40.5% des cas. Une chirurgie radicale a été indiquée de première intention dans 57 cas, après échec du traitement médical dans 16 cas et après échec d'une réduction endométriale dans 14 cas. L'analyse histologique des pièces d'hystérectomie trouve des myomes associés dans 32.18% des cas, une hyperplasie de l'endomètre dans 13.79%, des polypes dans 5.74% et une atrophie de l'endomètre dans 3.44%. L'adénomyose, maladie énigmatique, échappe toujours à une stratégie thérapeutique bien codifiée, et demeure étroitement liée à l'hystérectomie. Son dépistage chez des femmes de plus en plus jeunes et à des stades moins avancés pourrait éviter l’évolution systématique vers les traitements radicaux. PMID:26834926

  20. Grupos españoles de cálculos ab initio de moléculas de interés astrofísico

    NASA Astrophysics Data System (ADS)

    Yáñez, M.

    Pocos campos de la química están tan bien adaptados a la modelización por medio de los métodos teóricos de la Química Cuántica como la Astroquímica y la Química de la Atmósfera, donde las interacciones moleculares son, generalmente, lo suficientemente pequeñas para que el modelo de molécula aislada funcione muy bien. En España son varios los grupos teóricos que dedican su esfuerzo de investigación, o parte de él, al estudio de moléculas o procesos de interés en Astrofísica o en atmósferas planetarias. Presentaremos diferentes ejemplos paradigmáticos de esta actividad en la que se exploran desde aspectos estructurales, hasta aspectos espectroscópicos y dinámicos. Entre los últimos, cabe destacar estudios en los que se demuestra la importancia de procesos a dos estados, prohibidos por espín, en la formación astrofísica de diversos derivados de interés. En el tratamiento espectroscópico se han hecho esfuerzos interesantes, que han aunado teoría y experimento, en el estudio de sistemas relevantes desde el punto de vista atmosférico, como los hidratos de ácido nítrico, o el tratamiento espectroscópico de moléculas no rígidas. No menos interesantes son los estudios de fotoabsorción de radicales o de procesos multifotónicos. Son particularmente abundantes los estudios dedicados a la reactividad específica de sistemas de interés astrofísico o atmosférico, con el objetivo de esclarecer vías de formación de determinados compuestos o de proporcionar mecanismos que permitan identificar las etapas reactivas limitantes de reacciones de interés en esos medios y sobre los que no existía información previa. Así, por ejemplo, se han publicado interesantes estudios sobre la formación o propiedades de compuestos de fósforo, de silico o de azufre o sobre mecanismos de reacción en los que intervienen el ozono, el radical nitrato, el radical OH u otras especies. Finalmente, son también particularmente relevantes los estudios que varios

  1. Structure-property relationships of flexible polyurethane foams

    NASA Astrophysics Data System (ADS)

    Aneja, Ashish

    This study examined several features of flexible polyurethane foams from a structure-property perspective. A major part of this dissertation addresses the issue of connectivity of the urea phase and its influence on mechanical and viscoelastic properties of flexible polyurethane foams and their plaque counterparts. Lithium salts (LiCl and LiBr) were used as additives to systematically alter the phase separation behavior, and hence the connectivity of the urea phase at different scale lengths. Macro connectivity, or the association of the large scale urea rich aggregates typically observed in flexible polyurethane foams was assessed using SAXS, TEM, and AFM. These techniques showed that including a lithium salt in the foam formulation suppressed the formation of the urea aggregates and thus led to a loss in the macro level connectivity of the urea phase. WAXS and FTIR were used to demonstrate that addition of LiCl or LiBr systematically disrupted the local ordering of the hard segments within the microdomains, i.e., it led to a reduction of micro level connectivity or the regularity in segmental packing of the urea phase. Based on these observations, the interaction of the lithium salt was thought to predominantly occur with the urea hard segments, and this hypothesis was confirmed using quantum mechanical calculations. Another feature of this research investigated model trisegmented polyurethanes based on monofunctional polyols, or "monos", with water-extended toluene diisocyanate (TDI) based hard segments. The formulations of the monol materials were maintained similar to those of flexible polyurethane foams with the exceptions that the conventional polyol was substituted by an oligomeric monofunctional polyether of ca. 1000 g/mol molecular weight. Plaques formed from these model systems were shown to be solid materials even at their relatively low molecular weights of 3000 g/mol and less, AFM phase images, for the first time, revealed the ability of the hard

  2. Etude de quelques fonctionnelles du mouvement brownien et de certaines propriétés de la diffusion unidimensionnelle en milieu aléatoire

    NASA Astrophysics Data System (ADS)

    Monthus, Cécile

    This paper deals with functionals of Brownian motion that appear in various contexts, and with some properties of anomalous diffusion in a one-dimensional random environment. Section 2 explains why path integrals provide a powerful framework to compute probability distribution of functionals of Brownian motion. This approach is used to study winding properties of planar Brownian motion. Section 3 is devoted to an exponential functional of Brownian motion, which arise in particular in the study of transport properties of classical diffusion in a one-dimensional disordered system of finite length. This functional belongs to the field of multiplicative stochastic processes. Cet article porte sur l'étude des distributions de probabilité de quelques fonctionnelles du mouvement brownien qui interviennent dans divers contextes physiques. Le paragraphe 2 présente une méthode d'intégrale de chemin qui relieles distributions de probabilité de certaines fonctionnelles du mouvement brownien, à des fonctions de Green euclidiennes de la mécanique quantique. Cette approche permet notamment d'étudier certaines propriétés d'enroulementdu mouvement brownien plan, qu'il soit libre ou soumis à l'action d'un potentiel extérieur. Les fonctions d'échelle et les formes des lois asymptotiques à grand temps de l'enroulement autour d'un point dépendent des propriétés spectrales de basse énergied'une famille d'hamiltoniens contenant un potentiel vecteur de type Aharonov-Bohm.Le paragraphe 3 a pour l'objet l'étude de la loi de probabilité d'une fonctionnelle exponentielle du mouvement brownien qui intervient dans le cadnG de la diffusion unidimensionnelle aléatoire. Celle-ci apparaît notamment lorsque l'on s'intéresse à la distribution du flux de particules quitraverse un échantillon désordonné de taille finie, lorsque les particules diffusent classiquement, sous l'action d'une force aléatoire gelée distribuée comme un bruit blanc gaussien. Le spectre de

  3. Taxonomía de asteroides y cometas basada en los espectros de Lyapunov

    NASA Astrophysics Data System (ADS)

    Tancredi, G.; Motta, V.; Froeschlé, C.

    Estudiaremos dos familias de objetos que sufren encuentros cercanos con planetas, a saber: la familia de cometas de Júpiter (JF) y los asteroides cercanos a la Tierra (NEAs). El movimiento de estos objetos es caótico en una escala de tiempo corta. Más aún, debido a los cambios erráticos en los elementos orbitales, la comparación de los valores actuales da poca información acerca de la posible vinculación dinámica entre los objetos de una misma familia. Calculamos una estimación finita de los Exponentes Característicos de Lyapunov (LCE), los llamamos Indicadores Característicos de Lyapunov (LCI) para ambas familias y analizamos las características del espacio de fase donde tiene lugar el movimiento de estos objetos. Integrando en un período suficientemente largo (e.g. 20000 años), encontramos que el LCI alcanza un valor cuasi-constante. La mayoría de los miembros de ambas familias muestran una concentración de los tiempos de Lyapunov (inverso del LCI) de alrededor de 50-100 años (Tancredi, 1995, Astron & Astrop., 299, 288). La concentración de los tiempos de Lyapunov es mayor para la familia de Júpiter que para los NEAs. Entre estos últimos, la menor dispersión se da para aquellos que cruzan la órbita de la Tierra. Se demostró que el espectro de los `indicadores locales' (Froeschlé et. al., 1990, Cel. Mec. 56, 307) o ``números de estiramiento'' (Voglis and Contopoulos, 1994, J. Phys. A 26, 4899) (relacionados con el LCI) son invariantes y nos dan una información más completa sobre el comportamiento caótico. Mediante la comparación de espectros discutimos la similitud entre los objetos de una misma familia y analizamos las diferentes posibles rutas al caos. Los espectros se clasifican mediante la comparación de los momentos de las distribuciones de los `números de estiramiento'. Aplicamos un método de agrupamiento jerárquico (Zappala et. al., 1990, Astron. J. 100, 2030) para identificar ``familias'' de espectros (grupos de espectros

  4. Estudio teórico de la distribución catiónica en la capa octaédrica de silicatos laminares

    NASA Astrophysics Data System (ADS)

    Hernández-Laguna, A.

    Los silicatos laminares son unos minerales de gran extensión en la corteza de nuestro y otros planetas, y se ha detectado su presencia en masas de partículas de polvo interplanatario. Están formados por láminas estructuradas en una capa tetraedros de sílice y una de octaédros de oxihidroxido de aluminio. Según el número de capas y la disposición aparecen distintos minerales. Además, también pueden aparecer distintos minerales como consecuencia de la substitución isomórfica de cationes en la capas, en particular, Al(III) por Si en la capa tetraédrica y Fe(III) y/o Mg(II) por Al(III) en la octaédrica. Cuando el catión substituyente presenta un estado de oxidación más bajo que al que substituye genera carga negativa que tiene que neutralizarse con cationes que se disponen en el espacio interlaminar. En este trabajo vamos a estudiar, mediante distintos métodos computacionales, las distribuciones de dichos cationes de substitución en la capa octaédrica de silicatos laminares 2:1 (dos capas tetraédricas y en medio una octaédrica), en particular, en los minerales esmectitas e ilitas. En primer lugar, estudiaremos la distribución de dichos cationes en la capa octaédrica en un modelo de gas reticular por el método de Monte Carlo, minimizando el número de pares de cationes Al, Fe y Mg de nuestro modelo con respecto a los procedentes de resultados espectroscópicos de muestras de minerales. Posteriormente, y mediante un modelo de potenciales empíricos, estudiamos la energética de las distribuciones binarias en dichos minerales, generando unos potenciales de interacción intercambio a dos y tres cationes (extrapolables a cualquier filosilicato) que son la base para una investigación Monte Carlo-"simulated-annealing" en la que se encuentran las transiciones de fase y las estructuras ordenadas, dependiendo dichas estructuras y la temperatura de cambio de fase de la de la naturaleza y concentración de los cationes de substitución. También se han

  5. [Not Available].

    PubMed

    San Mauro Martín, Ismael; Cevallos, Vanesa; Pina Ordúñez, Diana; Garicano Vilar, Elena

    2016-01-01

    Introducción: existen alteraciones frecuentes en la alimentación de la población infantil femenina, y especialmente en atletas de deportes estéticos por la presión ejercida para mantener un cuerpo.Objetivos: evaluar los aspectos nutricionales, antropométricos y la percepción del peso de niñas que realizan gimnasia rítmica frente a un grupo control.Métodos: estudio descriptivo comparativo. Se compararon 25 niñas gimnastas con 25 niñas no gimnastas (control). Se realizó una valoración antropométrica, mediante protocolo ISAK, y nutricional, mediante un registro dietético de siete días; así como una valoración cuantitativa y cualitativa de la ingesta alimentaria, mediante el software DIAL. Se rellenó un cuestionario de hábitos y sobre la percepción de su peso corporal.Resultados: los datos antropométricos no presentaron diferencias significativas entre ambos grupos, excepto en los pliegues cutáneos y el porcentaje de grasa, el cual era estadísticamente inferior en gimnastas. La ingesta energética (1.413 ± 283 Kcal/día) de las gimnastas era inferior a la recomendada por la Food and Nutrition Board de acuerdo a su edad. La distribución de los macronutrientes cumplía con los valores normales establecidos (10-30% proteínas, 45-65% hidratos, 20-35% grasas). El 32% de las gimnastas y el 36,4% de las niñas control consideraron que les gustaría pesar menos.Conclusión: teniendo en cuenta la intensa actividad de las gimnastas, sus requerimientos energéticos deberían ajustarse a ello, ya que esto contribuirá a su desarrollo y crecimiento y a una mejor ejecución del ejercicio. En la muestra estudiada, el consumo de alimentos de las gimnastas se aleja de una alimentación equilibrada. No se observaron comportamientos diferentes en la percepción del peso entre ambos grupos. PMID:27571660

  6. Anévrismes de l'aorte abdominale sous-rénale rompus: aspects chirurgicaux à Dakar: à propos de 6 observations

    PubMed Central

    Dieng, Papa Adama; Diop, Momar Sokhna; Ba, Papa Salmane; Diatta, Souleymane; Gaye, Magaye; Sow, Ndeye Fatou; Diagne, Papa Amath; Sene, Etienne Birame; Ciss, Amadou Gabriel; Ndiaye, Assane; Ndiaye, Mouhamadou

    2015-01-01

    La rupture des anévrismes de l'aorte est une situation catastrophique. La chirurgie ouverte et le traitement endovasculaire sont débattus comme option. Dans cette étude sont évaluées les modalités du traitement chirurgical et ses résultats sur 6 malades opérés pour rupture d'un anévrysme de l'aorte abdominale sous-rénale. Dans 4 cas, il s'agissait d'une « rupture contenue » dans le péritoine pariétal postérieur, avec un hématome péri vertébral. Dans les 2 autres cas, il s'agissait d'une rupture en péritoine libre. Tous les malades avaient bénéficié après contrôle de l'hémostase d'une mise à plat de l'anévrisme suivie de greffe d'une prothèse aortique. Des complications précoces étaient notées chez 2 patients à type d'insuffisance rénale aigue et de poussée hypertensive. La mortalité opératoire était de 16,66%. La morbi-motalité des anévrismes rompus de l'aorte abdominale est particulièrement élevée, d'où la nécessité d'un dépistage précoce des patients à risque et l'introduction de la chirurgie endovasculaire. PMID:26587142

  7. Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

    NASA Astrophysics Data System (ADS)

    Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit

    2014-03-01

    Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (Tg) of these DEs are ˜195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ˜100-150 K above their individual Tgs. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH3CONH2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.

  8. Medium decoupling of dynamics at temperatures ˜100 K above glass-transition temperature: A case study with (acetamide + lithium bromide/nitrate) melts

    NASA Astrophysics Data System (ADS)

    Guchhait, Biswajit; Daschakraborty, Snehasis; Biswas, Ranjit

    2012-05-01

    Time-resolved fluorescence Stokes shift and anisotropy measurements using a solvation probe in [0.78CH3CONH2 + 0.22{f LiBr + (1-f) LiNO3}] melts reveal a strong decoupling of medium dynamics from viscosity. Interestingly, this decoupling has been found to occur at temperatures ˜50-100 K above the glass transition temperatures of the above melt at various anion concentrations (fLiBr). The decoupling is reflected via the following fractional viscosity dependence (η) of the measured average solvation and rotation times (⟨τs⟩ and ⟨τr⟩, respectively): ⟨τx⟩ ∝ (η/T)p (x being solvation or rotation), with p covering the range, 0.20 < p < 0.70. Although this is very similar to what is known for deeply supercooled liquids, it is very surprising because of the temperature range at which the above decoupling occurs for these molten mixtures. The kinship to the supercooled liquids is further exhibited via p which is always larger for ⟨τr⟩ than for ⟨τs⟩, indicating a sort of translation-rotation decoupling. Multiple probes have been used in steady state fluorescence measurements to explore the extent of static heterogeneity. Estimated experimental dynamic Stokes shift for coumarin 153 in these mixtures lies in the range, 1000 < Δνt/cm-1 < 1700, and is in semi-quantitative agreement with predictions from our semi-molecular theory. The participation of the fluctuating density modes at various length-scales to the observed solvation times has also been investigated.

  9. Comparison study of five different display modalities for whole slide images in surgical pathology and cytopathology in Europe

    NASA Astrophysics Data System (ADS)

    D'Haene, Nicky; Maris, Calliope; Rorive, Sandrine; Moles Lopez, Xavier; Rostang, Johan; Marchessoux, Cédric; Pantanowitz, Liron; Parwani, Anil V.; Salmon, Isabelle

    2013-03-01

    User experience with viewing images in pathology is crucial for accurate interpretation and diagnosis. With digital pathology, images are being read on a display system, and this poses new types of questions: such as what is the difference in terms of pixelation, refresh lag or obscured features compared to an optical microscope. Is there a resultant change in user performance in terms of speed of slide review, perception of adequacy and quality or in diagnostic confidence? A prior psychophysical study was carried out comparing various display modalities on whole slide imaging (WSI) in pathology at the University of Pittsburgh Medical Center (UPMC) in the USA. This prior study compared professional and non-professional grade display modalities and highlighted the importance of using a medical grade display to view pathological digital images. This study was duplicated in Europe at the Department of Pathology in Erasme Hospital (Université Libre de Bruxelles (ULB)) in an attempt to corroborate these findings. Digital WSI with corresponding glass slides of 58 cases including surgical pathology and cytopathology slides of varying difficulty were employed. Similar non-professional and professional grade display modalities were compared to an optical microscope (Olympus BX51). Displays ranged from a laptop (DELL Latitude D620), to a consumer grade display (DELL E248WFPb), to two professional grade monitors (Eizo CG245W and Barco MDCC-6130). Three pathologists were selected from the Department of Pathology in Erasme Hospital (ULB) in Belgium to view and interpret the pathological images on these different displays. The results show that non-professional grade displays (laptop and consumer) have inferior user experience compared to professional grade monitors and the optical microscope.

  10. Frequency-Comb Referenced Spectroscopy of νb{4} and νb{5} Hot Bands in the νb{1}+νb{3} Combination Band of C2H2

    NASA Astrophysics Data System (ADS)

    Twagirayezu, Sylvestre; Cich, Matthew; Sears, Trevor; McRaven, C.; Hall, Gregory

    2015-06-01

    Doppler-free transition frequencies for νb{4} and νb{5} hot bands in the band of C2H2 have been measured using saturation dip spectroscopy with an extended cavity diode laser referenced to a frequency comb. The frequency accuracy of the measured transitions, as judged from line shape model fits and the spectrometer stability, is better than 30 kHz. This is some 2-3 orders of magnitude improvement on the accuracy and precision of previous measurements of the line positions derived from the analysis of high-resolution Fourier transform infrared absorption spectra. The data were analyzed by determining the upper state energies, using known lower state level positions, and fitting them to a J(J+1) polynomial expansion to identify perturbations. The results reveal that the upper rotational energy level structure is mostly regular but suffers J-localized perturbations causing level shifts between one and several hundred MHz. These perturbations are due to accidental near degeneracies with energy levels of the same J and larger bending vibrational excitation. Acknowledgements: We are most grateful to Prof. D.S Perry (U. of Akron) and Prof. M. Herman (U. Libre de Bruxelles) for providing us with detailed results from their work and helpful discussions. Work at Brookhaven National Laboratory is funded by the Division of Chemical Sciences, Geosciences and Biosciences within the Offices of Basic Energy Sciences, Office of Sciences, U.S. Department of Energy under Contract Nos. DE-AC02-98CH10886 and DE-SC0012704.