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Sample records for termo-radiosensibilidad del precursor

  1. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I.-Development of the in vivo culture and effects induced by the hyperthermia; Termo-radiosensibilidad del precursor hematopoyetico que origina las series granulocitica y macrofaga de raton. I.- Desarrollo del cultivo in vivo y efectos producidos por la hipertermia

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    Bueren, J. A.; Nieto, M.

    1983-07-01

    The present report shows the agar diffusion chamber technique for culturing granulocyte- macrophage precursor cells, obtained from mice bone marrow. Diffusion chambers containing the bone marrow suspension are implanted intraperitoneally Into mice and constitute a compartment which avoids the migration of cells, but allows the transit of the mouse biological fluxes, necessary for the cellular proliferation. By means of this technique, we studied the lethal effects of the hyperthermia on the precursors and their capacity to repair sublethal damage. (Author) 129 refs.

  2. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I I . - X- irradiation effects and influence of hyperthermia on the radiosensitivity; Termo-radiosensibilidad del precursor hematopoyetico que origina las series granulocitica y macrofaga de raton. II. - Efectos producidos por la radiacion X e influencia de la hipertermia sobre la radiosensibilidad celular

    Energy Technology Data Exchange (ETDEWEB)

    Bueren, J. A.; Nieto, M.

    1983-07-01

    The effects of the X-irradiation on the viability of the granulocyte-macrophage precursors, has been determined by means of the agar diffusion chamber culture technique. The results show the high radiosensitivity of these cells, with survival parameter similar to those previously reported in the literature about different granulocyte-macrophage precursors. When a hyperthermic treatment is performed prior to the X-irradiation, a radiosensitization phenomenon is observed due to the synergism existent between hyperthermia and X rays on the lethality of the precursors. (Authors) 37 refs.

  3. Internacional Situacionista, un movimiento precursor del 'Performance Art'

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    Celia Balbina Fernández Consuegra

    2014-10-01

    Full Text Available El gran pecado de este movimiento conocido como Internacional Situacionista fue intentar destruir el orden establecido, el simulacro de nuestra realidad, construido y manipulado a través de los medios de información. Inclusivo, desde sus orígenes en los años cuarenta, este movimiento como ningún otro contemplaba todas las formas de creación: plástica, teatro, performance, cine, fotografía, literatura, poesía, tocando la política, la moral, y la vida misma. Sus conceptos ideológicos, elaborados de manera clara en sus numerosos textos, denuncian la brutal alineación que produce la sociedad de consumo, proponiendo una serie de estrategias para la liberación del individuo, bases que giran alrededor de la creación de situaciones. La situaciones fueron actos efímeros, auténticos, irrepetibles y por ello, imposibles de mercantilizar. Una de sus situaciones fue la acción contra la asamblea de críticos de arte internacionales en 1958. Las situaciones generadas dentro del movimiento sentaron las bases para acuñar el término Performance Art en los años setenta. 

  4. Miguel del Barco, naturalista y precursor de la Geografía moderna

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    Héctor Ochoterena Fuentes

    1981-01-01

    The scientific panorama of New Spain in the eighteenth century is concisely revised in order to situate the work of Miguel del Barco as a naturalist. The fossiliferous localities mentioned by this author and the reflections which led him to deduce the emersion of the Californian peninsula are treated with detail. Because of his work, analyzed from a geografical point of view, he can be considered as a precursor of this science.

  5. Miguel del Barco, naturalista y precursor de la Geografía moderna

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    Héctor Ochoterena Fuentes

    1981-01-01

    Full Text Available The scientific panorama of New Spain in the eighteenth century is concisely revised in order to situate the work of Miguel del Barco as a naturalist. The fossiliferous localities mentioned by this author and the reflections which led him to deduce the emersion of the Californian peninsula are treated with detail. Because of his work, analyzed from a geografical point of view, he can be considered as a precursor of this science.

  6. William Stanley Jevons: Precursor del pensamiento económico neoconservador

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    Emmanuel Borgucci

    2006-01-01

    Full Text Available El siguiente ensayo tiene el objetivo de demostrar que el pensamiento económico neoconservador (neoliberal no nació con las ideas que en materia económica porponían los teóricos de la oferta, las expectativas racionales, los monetaristas o los seguidores de la nueva hacienda pública conservadora. La economía neoconservadora tuvo en W.S. Jevons a uno de sus precursores más importantes. Esta afirmación se sustenta en tres razones: Su método de estudio, sus aportaciones en el campo de su teoría del intercambio, los precios relativos y su teoría del trabajo. Se concluye, que el discurso económico propuesto por W.S. Jevons contribuyó de manera decisiva al desarrollo y consolidación de un tipo de pensamiento económico que privilegia el uso del análisis formal y que se adapta a la forma moderna de hacer negocios en el mundo capitalista.

  7. Precursores del "consenso": itinerarios de algunas ideas en Brasil y Argentina, 1961-1991

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    Hernán Ramírez

    2010-12-01

    Full Text Available Nos proponemos seguir, analizando al Instituto de Pesquisas e Estudos Sociais, la Fundación de Investigaciones Económicas Latinoamericanas y la Fundación Mediterránea, algunos caminos recorridos por precursores de las políticas implementadas en Brasil y Argentina como pertenecientes al "Consenso de Washington", que han sido consecuencia de un lento proceso estructural abierto con la crisis del modelo desarrollista y del fordismo, lo que llevó al quiebre del Estado y a una mayor concentración económica que demandaban respuestas de un arsenal teórico y técnico diferente, ahora procuradas por grupos empresariales y cuadros técnicos que concomitantemente a su enraizamiento local se insertarían en redes internacionales, en su mayoría alentados y supervisados por instituciones estadunidenses y multilaterales, y que encontraron en los gobiernos autoritarios un medio de eliminar sus antiguos o potenciales competidores, permitiendo que un cuerpo común de ideas surgiese, hiciese pie y conquistase legitimidad.We intend to continue, analyzing the Instituto de Pesquisas e Estudos Sociais, the Fundación de Investigaciones Económicas Latinoamericanas and the Fundación Mediterránea, some paths itineraries by precursors of the policies implemented in Brazil and Argentina as belonging to the "Washington Consensus", which have been the result of a slow open section with the crisis of the developmental model and Fordism, which led to the breakdown of the state and greater economic, demanding answers from a different theoretical and technical arsenal, now procured by groups business and technical executives who concomitantly to its local roots in international networks would be inserted, mostly encouraged and monitored by North-American institutions and multilateral agencies, and they found in authoritarian governments to eliminate half its former or potential competitors, allowing a common body of ideas arise, would make walking and conquer

  8. Entrevista radial a Eugenio Espejo como precursor del periodismo en el Ecuador.

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    Chávez Rodríguez, Jacqueline Alexandra; Fernández Pincay, Yuri Elizabeth

    2016-01-01

    The communicative product "Radio interview to Eugenio Espejo as Precursor of Journalism in Ecuador" aims to convey a different and dynamic the story about the beginning of journalism in our country, from the first paper entitled "Primicias de la Cultura de Quito" in 1792. This radio production has been prepared under a comprehensive literature research paper the same as have studied and written about the life of this character. It has also taken into account the Lati...

  9. Esbozo para una biografía del precursor Pedro Fermín Vargas

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    Guillermo Hernández de Alba

    1979-04-01

    Full Text Available Dos siglos corridos desde su nacimiento, más de uno y medio de la proclamación de la Independencia Nacional, han sido necesarios para que la memoria de Pedro Fermín de Vargas sea públicamente restituida a su patria, que al conocer y estudiar su vida extraordinaria lo celebrará entre los precursores de su libertad, lo admirará por la excelencia de su clara inteligencia y de su formación intelectual y le dará sitio de honor en los anales de su historia económica porque es capaz de proyectar, con arte de visionario, el estudio perfecto de la producción nacional y la distribución de su riqueza latente.

  10. Juan de Mariana. Heredero de la escuela de Salamanca y precursor del liberalismo

    OpenAIRE

    Fernández Álvarez, Ángel Manuel

    2015-01-01

    Juan de Mariana (1536-1624) fue un autor español de la orden de los jesuitas que destacó por escribir el primer libro moderno de historia de España. Por encargo del rey Felipe II, publicó en latín Historia de rebus Hispaniae en 1592 y su propia traducción al español con el título Historia general de España en 1601. Esta investigación doctoral tiene como objetivo analizar sus principales obras de economía política De Rege et Regis Institutione (1599) y De Monetae Mutatione (1609), junto con su...

  11. EFECTO DEL CONTENIDO DE SODIO EN LA OBTENCIÓN DE Na+ -B-ALÚMINA UTILIZANDO EL MÉTODO DE PRECURSOR POLIMÉRICO

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    VANESSA RUIZ

    2011-01-01

    Full Text Available En este trabajo se muestran los resultados obtenidos al emplear el metodo de precursor polimerico (Pechini para sintetizar polvos ceramicos de Na + B Àalumina, utilizando sales inorganicas, tomando como parametro de estudio la cantidad inicial del precursor de sodio y su efecto sobre la fase cristalina obtenida al final del proceso. Los polvos fueron caracterizados utilizando espectroscopia Infrarroja (FTIR, Difraccion de Rayos X (DRX y Microscopia Electronica de Barrido (MEB. Se encontro que el efecto de la cantidad de sodio inicial en la muestra es determinante en la naturaleza del producto final obtenido. Utilizando la cantidad estequiometrica de NaOH requerida, para la obtencion del compuesto NaAl11O17, se obtuvo al final del proceso (1450oC a-alumina y B-alumina y/o Na2Al2xO3x1 en muestras tratadas termicamente entre 1000oC y 1350oC. Cuando se uso una mayor cantidad de NaOH, muestra no estequiometrica, se obtuvo un solido con el compuesto NaAl11O17 como fase mayoritaria.

  12. Entre indios e inmigrantes: el pensamiento nacionalista y los precursores del folklore en la antropología argentina del cambio del siglo (XIX-XX

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    De Jong, Ingrid

    2005-08-01

    Full Text Available The objective of this article is to analyze the influence of ideas of culturalist nationalism in the configuration of studies of folklore in Argentine anthropology at the turn of the 20th Century. Following the production of leading researchers of folklore during this period allows us to detect the focus of the essentialist conception of the underlying nationality, as well as the the importance given to the indigenous and Spanish contributions to the «creole essence» as conceived by society´s elite sectors as the ethnic foundations of nationality.

    El artículo tiene como objetivo el análisis de la influencia de las ideas del nacionalismo culturalista en la configuración de los estudios de folklore en la antropología argentina durante las décadas que rodean la transición del siglo XIX al XX. El seguimiento de la producción de los principales investigadores en folklore en este período permite detectar la concepción esencialista de la nacionalidad subyacente a sus enfoques, así como las operaciones de jerarquización de los aportes indios y españoles a la «esencia criolla» concebida por los sectores de elite como fundamento étnico de la nacionalidad.

  13. Carbón activado: evaluación de nuevos precursores y del proceso de activación con dióxido de carbono

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    Plaza Recobert, Minerva

    2015-01-01

    Los resultados obtenidos han mostrado como el CO2 es un agente activante apropiado y muy versátil para la generación de una amplia variedad de carbones activados. De este modo, con una adecuada selección de la materia prima y el tratamiento de la misma, se puede controlar el desarrollo del tamaño de porosidad deseado durante el proceso de activación con CO2: carbones microporosos, carbones mesoporosos y carbones con meso y macroporosidad. La evaluación de dos nuevos precursores lignocelulósic...

  14. Evaluación y conducta recomendada en presencia de precursores vítreorretinianos del desprendimiento de retina

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    Ceija Molina Cisneros

    Full Text Available Los cambios y las variaciones anatómicas vítreorretinianas predisponen al desprendimiento de retina regmatógeno, por lo que su conocimiento es de vital importancia para el tratamiento adecuado de los pacientes. Por ello se decidió realizar una revisión acerca de los elementos más importantes al respecto, con el objetivo de actualizar los conocimientos existentes sobre el tema. Estos precursores comprenden tres entidades que, por su fisiopatología, pueden estar presentes en la historia natural de esta afección: Desprendimiento de vítreo posterior, degeneraciones periféricas y desgarro de retina (sintomáticos y asintomáticos. Además, algunas situaciones de riesgo como la cirugía de catarata, la capsulotomía posterior con YAG-láser, los traumatismos y la miopía alta pueden favorecer también al desprendimiento de retina. Estos precursores, por lo general, se hacen más evidentes después de los 40 años, sin predilección por sexo o características raciales y están muy relacionadas con cambios vítreos o su licuefacción. El conocimiento básico y actualizado de estas entidades, así como de los factores de riesgo asociados al desprendimiento de retina es importante para el adecuado manejo y el control de las complicaciones. En la revisión se describen con claridad los pilares fundamentales para el diagnóstico y tratamiento de este tipo de situaciones clínicas.

  15. Modificación química del precursor de titanio para obtener soles estables de silice – titania: Uso de acetilacetona

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    Rodríguez-Páez, J. E.

    2004-02-01

    Full Text Available Sol-gel processing has become a well established technique for producing ceramic powders or glasses. This processing has been utilized to synthesize several interesting systems, e.g. the SiO2 – TiO2 system. A major concern in the stable multicomponent geles is that the hydrolysis and condensation velocities are diferent for each precursor, TEOS and Ti(OBu4 in this work. The chemical control of these reactions is currently performed by adding complexing reagents that react with metal alkoxides at a molecular level, giving rise to new molecular precursors of different structure, reactivity and functionanality. This paper shows that stable TEOS – Ti(OBu4 – H2O sol can be reproducibly prepared in the presence of acetylacetone. We shall then show that the acac behaves as a ligand, directly bonded to the titanium ion. Thus the formation of precipitate is avoided. Infra-red spectroscopy (FTIR and viscosity measures were used to demostrated this behaviour of the system.

    La técnica Sol-Gel se ha utilizado para sintetizar una serie de sistemas multicomponentes, entre ellos SiO2 – TiO2. El mayor problema en la obtención de geles multicomponentes estables es la desigual velocidad de hidrólisis y condensación que presentan los alcóxidos precursores de los cationes de interés. En este trabajo se muestra cómo adicionando acetilacetona, acacH, al sistema TEOS – Ti(OBu4 – H2O se puede obtener un sol estable. Se tomaron diferentes concentraciones de los precursores de silicio y titanio y una sola concentración de acacH. Se utilizó espectroscopia infrarroja, FTIR, para identificar los grupos funcionales presentes en el sistema y además se midió regularmente la viscosidad para determinar cualitativamente el avance de la policondensación del sistema.

  16. Analytical control of the synthesis of the trithio and its precursors by gas chromatography; Control por cromatografia en fase gaseosa de la sintesis del trithion y de sus precursores

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    Gonzalez Moreno, M. P.; Perez Garcia, M. M.; Angoso Marina, M.

    1979-07-01

    The synthesis of pesticide Trithio and its precursors has been controlled by G.L. selecting the best separation conditions and responses. The following columns have been used: 20% FFAP on chromo sorb W (a.w.) D.M.C.S. for organophosphate precursor glass column of 5 % Silicone SE-30 on chromo sorb G (a.w.) D.H.C.S. for S-(p-chlorophenyl-chloro methyl) and 12 % Silicone SE-30 modified with 8 % of Neopentyl-glicolsuccinate for Trithio. The relative retention times, retention indices and relative responses for. Trithio and its precursors have been calculated. (Author) 9 refs.

  17. Efecto de la naturaleza del precursor sobre las caracteristicas de las nanoparticulas de SnO2 sintetizadas Effect of the precursor's nature on characteristics of synthesized SnO2 nanoparticles

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    Carlos E. Ararat-Ibarguen

    2007-01-01

    Full Text Available Tin oxide (SnO2 is widely used in industry as raw material for electronic devices, plating of different types of materials, for dyes and pigments, for electroplating, heterogeneous catalysis, etc. In this work SnO2 was obtained by a controlled precipitation method with special attention to the effects the tin precursor has on the microstructure of the final product. The most appropriate pH for obtaining SnO2 with the rutile structure as the main phase is 6.25 for SnCl2 and 6.40 for SnSO4. After heat treatment at 600 °C, particles of nanometric order (~10 - 30 nm approx were obtained. The characterization of the solid phase was made by X-ray diffraction (XRD, thermal analysis (DTA/TG, transmission electron microscopy (TEM and Fourier transformed infrared spectroscopy (FTIR.

  18. El FGF2 como regulador de la actividad mitogénica de precursores neurales en el nicho celular del cerebro embrionario de ratón

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    Lamus Molina, José Francisco

    2016-01-01

    A lo largo de la vida del individuo, las células precursoras neurales se encuentran alojadas en microentornos especializados conocidos como nichos germinales neurogénicos, que garantizan su mantenimiento y posibilitan la generación de nuevas neuronas, experimentando su momento de máxima actividad neurogénica durante el desarrollo. El fluido cerebroespinal embrionario (eCSF) ha sido identificado como uno de los elementos esenciales del nicho neurogénico del cerebro embrionario, contactando de ...

  19. Las Instrucciones del año XIII: Artigas como precursor constitucional de la integración económica y social regional

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    Luis Benjamín Manzoni Rubio

    2015-10-01

    Full Text Available Iniciamos el presente trabajo pensando en un concepto nietzscheano sobre el estudio de la historia, según el cual; "el pasado no debe ser interpretado más que por un presente más fuerte que él", Y que para nosotros, tiene la significación de poner en primer plano la importancia de la adecuada ubicación temporal del intérprete y de su punto de vista personal, siempre que sea el resultado del más libre examen y esté avalado por un método rigurosamente empírico. (...Contenido: Introducción. Método de interpretación historiográfica predominante. Justificación del enfoque propuesto en ciencia del derecho constitucional. Algunas nociones provisionales y elementales sobre federalismo institucional, descentralización política eintegración económica y de sus relaciones e implicancias. El federalismo rioplatense: sus principales antecedentes y causas determinantes. Examen estructural de las instrucciones orientales : la doble relación de instrumentalidad descentralización política-integración económica-consolidación del estado nacional federal. Algunas conclusiones provisionales

  20. Correlación clínico patológica del cáncer cervical y precursores en una población de Lima periférica

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    Victoria Valer

    2005-06-01

    Full Text Available Objetivo: Determinar la prevalencia y los factores de riesgo del cáncer cervical y sus precursores en un grupo poblacional, con especial énfasis en el manejo de la enfermedad cervical preinvasiva. Diseño: Estudio prospectivo y descriptivo no aleatorio. Materiales y Métodos: Estudio realizado durante el año 2003, en mujeres del Centro de Salud de Piedra Liza (San Juan de Lurigancho en 120 pacientes con diagnóstico citológico de ASC, AGC, L-SIL, H-SIL y carcinoma; se realizó biopsia de las lesiones cervicales en 49 casos, para confirmar el diagnóstico citológico y correlacionarlo con el cuadro clínico y la colposcopia. Resultados: De los 120 casos de estudio citológico, 14 (11,5% fueron ASC; 67 (56% L-SIL, 34 (29% H-SIL, 3 (2,5% carcinoma escamoso y 2 (2% adenocarcinoma. De 49 biopsias, 12 casos fueron L-SIL, 32 H-SIL, 3 carcinoma escamoso invasor y 2 adenocarcinoma cervical, uno de ellos in situ. Conclusiones: Los resultados citológicos muestran que las lesiones escamosas intraepiteliales y el carcinoma cervical tuvieron alta prevalencia en este grupo poblacional.

  1. El trabajo precursor de Lluís Folch i Torres en la evaluación psicológica pericial del menor

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    Sáiz Roca, Milagros

    2009-01-01

    La Revolución industrial y su derivación en el aumento de la necesidad de mano de obra como consecuencia de la manufactura, produjeron, como es sabido, un tránsito del medio rural al medio urbano y de un país a otro, en busca de fortuna. La densidad poblacional se incrementó de tal manera, en algunos núcleos urbanos, que saturó el mercado de trabajo y aumentó el nivel de pobreza, haciendo proliferar un panorama donde el niño abandonado, que se buscaba la vida con delitos menores, era frecuent...

  2. Precursors and BRST symmetry

    Science.gov (United States)

    de Boer, Jan; Freivogel, Ben; Kabir, Laurens; Lokhande, Sagar F.

    2017-07-01

    In the AdS/CFT correspondence, bulk information appears to be encoded in the CFT in a redundant way. A local bulk field corresponds to many different non-local CFT operators (precursors). We recast this ambiguity in the language of BRST symmetry, and propose that in the large N limit, the difference between two precursors is a BRST exact and ghost-free term. This definition of precursor ambiguities has the advantage that it generalizes to any gauge theory. Using the BRST formalism and working in a simple model with global symmetries, we re-derive a precursor ambiguity appearing in earlier work. Finally, we show within this model that the obtained ambiguity has the right number of parameters to explain the freedom to localize precursors within different spatial regions of the boundary order by order in the large N expansion.

  3. Earthquakes: hydrogeochemical precursors

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    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  4. Preparation of thin films, with base to precursor materials of type Cu-In-Se elaborated by electrodeposition for the solar cells elaboration; Preparacion de peliculas delgadas, con base a materiales precursores del tipo Cu-In-Se, elaboradas por electrodeposito para la elaboracion de celdas solares

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.M. [Centro de Investigaciones en Energia, Universidad Nacional Autonoma de Mexico. Av. Xochicalco s/n. 62580 Temixco, Morelos (Mexico)

    1999-11-01

    Thin films of chalcogenide compounds are promising because they have excellent optoelectronic characteristics to be applied in solar cells. In particular, CuInSe{sub 2} and Cd Te thin films have shown high solar to electrical conversion efficiency. However, this efficiency is limited by the method of preparation, in this case, physical vapor deposition techniques are used. In order to increase the area of deposition t is necessary to use chemical methods, for example, electrodeposition technique. In this paper, the preparation of Cu-In-Se precursors thin films by electrochemical method is reported. These precursors were used to build solar cells with 7.9 % of efficiency. (Author)

  5. Wilson loops as precursors

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, Leonard [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States); Toumbas, Nicolaos [Department of Physics, Stanford University, Stanford, California 94305-4060 (United States)

    2000-02-15

    There is substantial evidence that string theory on AdS{sub 5}xS{sub 5} is a holographic theory in which the number of degrees of freedom scales as the area of the boundary in Planck units. Precisely how the theory can describe bulk physics using only surface degrees of freedom is not well understood. A particularly paradoxical situation involves an event deep in the interior of the bulk space. The event must be recorded in the (Schroedinger picture) state vector of the boundary theory long before a signal, such as a gravitational wave, can propagate from the event to the boundary. In a previous paper with Polchinski, we argued that the ''precursor'' operators which carry information stored in the wave during the time when it vanishes in a neighborhood of the boundary are necessarily non-local. In this paper we argue that the precursors cannot be products of local gauge invariant operators such as the energy momentum tensor. In fact gauge theories have a class of intrinsically non-local operators which cannot be built from local gauge invariant objects. These are the Wilson loops. We show that the precursors can be identified with Wilson loops whose spatial size is dictated by the UV-IR connection. (c) 2000 The American Physical Society.

  6. Behavior of Electrochemically Prepared CuInSe{sub 2} as Photovoltaic Absorber in thin Film Solar Cells; Comportamiento del CuInSe{sub 2} Basado en Precursores Electrodepositados como Absorbente Fotovoltaico en Celulas Solares de Lamina Delgada

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C.; Martinez, M. A.; Dona, J. M.; Herrero, J.; Gutierrez, M. T. [Ciemat.Madrid (Spain)

    2000-07-01

    Two different objective have been pursued in the present investigation: (1) optimization of the CuInSe{sub 2} preparation parameters from electrodeposited precursors, and (2) evaluation of their photovoltaic behavior by preparing and enhancing Mo/CuInSe{sub 2}/CdS/TCO devices. When Cu-In-Se precursors are directly electrodeposited, the applied potential fit is essential to improve the photovoltaic performance. Suitable absorbers have been also obtained by evaporing an In layer onto electrodeposited Cu-Se precursors. In this case, the substrate temperature during evaporation determines the CuInSe{sub 2} quality. Similar results have been reached by substituting typical Mo-Coated glass substrates by flexible Mo foils. Different TCO tested (ZnO and ITO) have been found equivalent as front electrical contact in the devices. Solar cell performance can be improved by annealing in air at 200 degree centigree. (Author) 46 refs.

  7. Peeling without precursors

    Science.gov (United States)

    Lister, John; Skinner, Dominic; Large, Tim

    2017-11-01

    The peeling by fluid injection of an elastic sheet away from a substrate is often regularised by invoking a thin prewetting film or a low-viscosity phase in the tip. Here we analyse fluid-driven peeling without such precursors, and consider an elastic sheet either bonded to, or simply laid on, an elastic substrate. To resolve the `elastic contact-line problem' that arises from viscous flow and beam theory, we determine the near-tip behaviour from lubrication theory coupled to the full equations of elasticity and fracture. The result is a law for the tip propagation speed in terms of the remote loading and the toughness of the sheet-substrate bonding (which might be zero). There are distinct modes of failure, according to whether there is slip ahead of the fluid front. The propagation-speed law gives rise to new similarity solutions for the spread of a fluid-filled blister in different regimes.

  8. Identified EM Earthquake Precursors

    Science.gov (United States)

    Jones, Kenneth, II; Saxton, Patrick

    2014-05-01

    Many attempts have been made to determine a sound forecasting method regarding earthquakes and warn the public in turn. Presently, the animal kingdom leads the precursor list alluding to a transmission related source. By applying the animal-based model to an electromagnetic (EM) wave model, various hypotheses were formed, but the most interesting one required the use of a magnetometer with a differing design and geometry. To date, numerous, high-end magnetometers have been in use in close proximity to fault zones for potential earthquake forecasting; however, something is still amiss. The problem still resides with what exactly is forecastable and the investigating direction of EM. After a number of custom rock experiments, two hypotheses were formed which could answer the EM wave model. The first hypothesis concerned a sufficient and continuous electron movement either by surface or penetrative flow, and the second regarded a novel approach to radio transmission. Electron flow along fracture surfaces was determined to be inadequate in creating strong EM fields, because rock has a very high electrical resistance making it a high quality insulator. Penetrative flow could not be corroborated as well, because it was discovered that rock was absorbing and confining electrons to a very thin skin depth. Radio wave transmission and detection worked with every single test administered. This hypothesis was reviewed for propagating, long-wave generation with sufficient amplitude, and the capability of penetrating solid rock. Additionally, fracture spaces, either air or ion-filled, can facilitate this concept from great depths and allow for surficial detection. A few propagating precursor signals have been detected in the field occurring with associated phases using custom-built loop antennae. Field testing was conducted in Southern California from 2006-2011, and outside the NE Texas town of Timpson in February, 2013. The antennae have mobility and observations were noted for

  9. PRECURSOR FLARES IN OJ 287

    Energy Technology Data Exchange (ETDEWEB)

    Pihajoki, P.; Berdyugin, A.; Lindfors, E.; Reinthal, R.; Sillanpaeae, A.; Takalo, L. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-21500 Piikkioe (Finland); Valtonen, M.; Nilsson, K. [Finnish Centre for Astronomy with ESO, University of Turku, FI-21500 Piikkioe (Finland); Zola, S.; Koziel-Wierzbowska, D. [Astronomical Observatory, Jagiellonian University, ul. Orla 171, PL-30-244 Krakow (Poland); Liakos, A. [Department of Astrophysics, Astronomy and Mechanics, University of Athens, GR 157 84 Zografos, Athens, Hellas (Greece); Drozdz, M.; Winiarski, M.; Ogloza, W. [Mount Suhora Observatory, Pedagogical University, ul. Podchorazych 2, PL-30-084 Krakow (Poland); Provencal, J. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Santangelo, M. M. M. [O.A.C. Osservatorio Astronomico di Capannori, Via di Valle, I-55060 Vorno, Capannori (Italy); Salo, H. [Department of Physical Sciences, University of Oulu, P.O. Box 3000, FI-90014 University of Oulu (Finland); Chandra, S.; Ganesh, S.; Baliyan, K. S., E-mail: popiha@utu.fi [Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India); and others

    2013-02-10

    We have studied three most recent precursor flares in the light curve of the blazar OJ 287 while invoking the presence of a precessing binary black hole in the system to explain the nature of these flares. Precursor flare timings from the historical light curves are compared with theoretical predictions from our model that incorporate effects of an accretion disk and post-Newtonian description for the binary black hole orbit. We find that the precursor flares coincide with the secondary black hole descending toward the accretion disk of the primary black hole from the observed side, with a mean z-component of approximately z{sub c} = 4000 AU. We use this model of precursor flares to predict that precursor flare of similar nature should happen around 2020.96 before the next major outburst in 2022.

  10. PAGOSA Sample Problem. Elastic Precursor

    Energy Technology Data Exchange (ETDEWEB)

    Weseloh, Wayne N. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Clancy, Sean Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-03

    A PAGOSA simulation of a flyer plate impact which produces an elastic precursor wave is examined. The simulation is compared to an analytic theory for the Mie-Grüneisen equation of state and an elastic-perfectly-plastic strength model.

  11. Preparation of superconductor precursor powders

    Science.gov (United States)

    Bhattacharya, Raghunath; Blaugher, Richard D.

    1995-01-01

    A process for the preparation of a precursor metallic powder composition for use in the subsequent formation of a superconductor. The process comprises the steps of providing an electrodeposition bath comprising an electrolyte medium and a cathode substrate electrode, and providing to the bath one or more soluble salts of one or more respective metals, such as nitrate salts of thallium, barium, calcium, and copper, which are capable of exhibiting superconductor properties upon subsequent appropriate treatment. The bath is continually energized to cause the metallic particles formed at the electrode to drop as a powder from the electrode into the bath, and this powder, which is a precursor powder for superconductor production, is recovered from the bath for subsequent treatment. The process permits direct inclusion of thallium in the preparation of the precursor powder, and yields an amorphous product mixed on an atomic scale to thereby impart inherent high reactivity. Superconductors which can be formed from the precursor powder include pellet and powder-in-tube products.

  12. The Innate Lymphoid Cell Precursor.

    Science.gov (United States)

    Ishizuka, Isabel E; Constantinides, Michael G; Gudjonson, Herman; Bendelac, Albert

    2016-05-20

    The discovery of tissue-resident innate lymphoid cell populations effecting different forms of type 1, 2, and 3 immunity; tissue repair; and immune regulation has transformed our understanding of mucosal immunity and allergy. The emerging complexity of these populations along with compounding issues of redundancy and plasticity raise intriguing questions about their precise lineage relationship. Here we review advances in mapping the emergence of these lineages from early lymphoid precursors. We discuss the identification of a common innate lymphoid cell precursor characterized by transient expression of the transcription factor PLZF, and the lineage relationships of innate lymphoid cells with conventional natural killer cells and lymphoid tissue inducer cells. We also review the rapidly growing understanding of the network of transcription factors that direct the development of these lineages.

  13. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  14. Obtención de silicatos de calcio empleando como precursores residuos sólidos. Influencia del mezclado de reactivos en fase seca o fase húmeda

    Directory of Open Access Journals (Sweden)

    Corpas Iglesias, F. A.

    2011-02-01

    Full Text Available The suitability of re-using residues marble, remaining from cutting marble, as a source of calcium-oxide, as well as the resultant ashes from the combustion of the wastes generated in the process of manufacturing boards from derivates of wood, as a source of silica, as raw material for the production of calcium silicate products has been determined. First of all, the influence of water has been studied in the initial phase of mixing residues. Marble and ashes have been mixed in molar relation CaO:SiO2 of 1:1 using two different ways: using a planetary ball mill (while in solid state or agitating at 90 ºC (2 h using a 60 wt% of water (while in humid state. Later, both mixtures were sintered at 1100 ºC (24 h. In order to use the obtained calcium-silicates as ceramic insulating thermal materials, the samples were compressed at 15 Tm obtaining bricks from which the technological properties have been studied. The ceramic materials obtained from mixing the residues in dry phase, as well as those obtained in the wet phase, can be used as thermal insulators, showing values of conductivity of 0.18 and 0.12 w/m2K, with an elevated resistance to compressive strength.

    Se ha determinado la posibilidad de reutilizar los residuos procedentes del corte de mármol, como fuente de óxido de calcio, y las cenizas resultantes de la combustión de los residuos generados en el proceso de fabricación de tableros de derivados de madera, como fuente de sílice. A partir de ambas materias primas, se obtienen silicatos de calcio. Se ha estudiado la influencia de agua en la fase inicial de mezclado de los residuos. Para ello mármol y cenizas se han mezclado en relación molar CaO:SiO2 1:1, en una primera ruta, en fase seca, empleando un molino de bolas, o en una segunda ruta, en fase húmeda, mediante agitación a 90 ºC (2 h empleando un 60 % en peso de agua. Posteriormente, ambas mezclas se sinterizan a 1100 ºC (24 h. Con

  15. Dinámica espacio-temporal de organismos precursores de marea roja en la costa Pacífica de América del Norte y Centroamérica

    Directory of Open Access Journals (Sweden)

    A.P Sierra-Beltrán

    2004-09-01

    Full Text Available La región costera del Pacífico de Centro y Norte America ha sido afectada de manera frecuente por fenómenos que se denominan proliferaciones algales nocivas o en inglés, "Harmful Algal Blooms" (HAB. A pesar de la gran cantidad de efectos en la salud pública, las actividades económicas y el medio ambiente, aún existe una abrumadora carencia de información en el tema. Esto no permite establecer si las causas principales de este evidente aumento en el número e intensidad de los eventos son naturales o antropogénicas. La incrementada utilización de las zonas costeras para actividades humanas encuentra paralelo en el denominado cambio climático, lo que dificulta discriminar entre la posible influencia de estos dos fenómenos. Series de datos de larga duración en regiones reducidas, así como las observaciones esporádicas realizadas cuando se presenta algún evento, nos permite comparar regímenes climáticos, condiciones geográficas, disponibilidad de nutrientes (incluyendo la eutroficación y parámetros oceanográficos que promueven o permiten el desarrollo y mantenimiento de las proliferaciones, haciendo evidentes cambios drásticos en la biodiversidad y la biogeografía de los organismos productores de HABThe Pacific coast of Central and North America has long been and still is impacted by the flourishing of microalgal populations known as Harmful Algal Blooms (HABs. The organisms that have caused recent HABs episodes in the region are among others, Gymnodinium catenatum, Pyrodinium bahamense var. compressum, and recently Cochlodinium cf. catenatum. In spite of the accumulated effects on the human health, the economic activities and the environment, scarce information is available on the subject. The augmented use of coastal zones for human activities is also paralleled by increased awareness of global climate changes. Thus, it is not an easy task to discriminate anthropogenic or natural phenomena, or both, as the major driving

  16. Precursor missions to interstellar exploration.

    Science.gov (United States)

    Wallace, R. A.

    This paper summarizes material developed over a three-month period by a JPL team of mission architects/analysts and advanced technology developers for presentation to NASA Headquarters in the summer of 1998. A preliminary mission roadmap is suggested that leads to the exploration of star systems within 40 light years of our Solar System. The precursor missions include technology demonstrations as well as missions that return significant new knowledge about the space environment reached. Three propulsion technology candidates are selected on the basis of allowing eventual travel to the nearest star taking 10 years. One of the three propulsion technologies has a near term version applicable to early missions (prior to 2010) - the solar sail. Using early sail missions other critical supporting technologies can be developed that will later enable Interstellar travel. Example precursor missions are sail demonstration missions, including a solar storm warning mission demonstrating a simple sail, a solar polar imaging mission using an intermediate sail, and a 200-AU Heliosphere Explorer mission using an advanced solar sail. Mission and technology strategy, science return, and potential mission spin-offs are described.

  17. Premarital precursors of marital infidelity.

    Science.gov (United States)

    Allen, Elizabeth S; Rhoades, Galena Kline; Stanley, Scott M; Markman, Howard J; Williams, Tamara; Melton, Jessica; Clements, Mari L

    2008-06-01

    Premarital precursors of infidelity were evaluated in a sample of 72 couples (N = 144) who were taking part in a longitudinal study of marriage. Premarital self-report and observational data were compared for couples who experienced infidelity and those who did not experience infidelity in the first years of marriage. Couples in which the male engaged in marital infidelity were characterized, premaritally, by significantly lower male sexual satisfaction, lower male positive communication, and higher female invalidation, whereas couples in which the female went on to engage in infidelity were characterized, premaritally, by significantly lower levels of female positive communication, higher levels of male and female negative communication, and higher levels of male and female invalidation. Implications of the findings for future research on the prediction and prevention of infidelity are discussed.

  18. Precursor/product antiport in bacteria

    NARCIS (Netherlands)

    Poolman, B.

    1990-01-01

    Many microorganisms metabolize their substrates (precursors) only partially and excrete the products of the metabolism into the medium. Although uptake of precursor and exit of product can proceed as two independent steps, there is increasing evidence that these processes are often linked and that

  19. Synthesis and structures of metal chalcogenide precursors

    Science.gov (United States)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

    1990-01-01

    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  20. Lesões precursoras do câncer cervicouterino: evolução histórica e subsídios para consulta de enfermagem ginecológica Lesiones precursoras del cáncer cervical-útero: evolución histórica consolidando la consulta de enfermería ginecológica Cervical-uterine cancer precursor lesions: historical evolution supporting the gynecological nursing consultation

    Directory of Open Access Journals (Sweden)

    Maria Cristina de Melo Pessanha Carvalho

    2010-09-01

    Full Text Available Estudo emergido de recorte de dissertação de mestrado, ilustrando a evolução histórica das lesões precursoras do câncer cervicouterino (LPCCU. Trata-se da história das LPCCU, delineando a relevância do conhecimento para prática do enfermeiro na área da saúde da mulher. O conceito de LPCCU inicia-se a partir do século XIX, dando início aos estudos das células alteradas. Objetivo: descrever as diversas fases da evolução histórica das alterações cervicais. Estudo qualitativo, descritivo-analítico, recorte temporal no período de 1940 a 2008. Dados levantados mediante bibliografia de fonte primária e recurso BIREME. Pontuaram-se as classificações que já existiram, destacando a Nomenclatura Brasileira, importante para corresponder às necessidades e o perfil da saúde das mulheres do Brasil. Este estudo é o ponto de partida para respaldar as práticas de consulta de enfermagem ginecológica com abordagens educativas, contemplando a população feminina em ações preventivas e incentivo ao tratamento.Estudio emergido de recorte de disertación de máster, ilustrando la evolución histórica de las lesiones precursoras del cáncer cervical-uterino (LPCCU. Se trata de la historia de las LPCCU, delineando la relevancia del conocimiento para la práctica del enfermero en cuidados en la salud de la mujer. El concepto de LPCCU se inicia a partir del siglo XIX, empezando los estudios de las células alteradas. Como objetivo: describir las diversas fases históricas de las alteraciones cervicales. Estudio cualitativo, descriptivo-analítico, recorte temporal en el período de 1940 hasta 2008. Datos acrecentados mediante bibliografía de fuente primaria y recurso BIREME. Se puntuó las diferentes clasificaciones que ya existieron, conde destaque para la nomenclatura brasileña, importante para corresponder a las necesidades y el perfil de la salud de las mujeres del Brasil. Esto estudio es el ponto de partida para respaldar las pr

  1. Precursor Parameter Identification for IGBT Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — Precursor parameters have been identified to enable development of a prognostic approach for insulated gate bipolar transistors (IGBT). The IGBT were subjected to...

  2. Progress in molecular precursors for electronic materials

    Energy Technology Data Exchange (ETDEWEB)

    Buhro, W.E. [Washington Univ., St. Louis, MO (United States)

    1996-09-01

    Molecular-precursor chemistry provides an essential underpinning to all electronic-materials technologies, including photovoltaics and related areas of direct interest to the DOE. Materials synthesis and processing is a rapidly developing field in which advances in molecular precursors are playing a major role. This article surveys selected recent research examples that define the exciting current directions in molecular-precursor science. These directions include growth of increasingly complex structures and stoichiometries, surface-selective growth, kinetic growth of metastable materials, growth of size-controlled quantum dots and quantum-dot arrays, and growth at progressively lower temperatures. Continued progress in molecular-precursor chemistry will afford precise control over the crystal structures, nanostructures, and microstructures of electronic materials.

  3. Biochemical Removal of HAP Precursors From Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.; Tucker, L.; Richards, J.

    1997-07-01

    This project addresses DOE`s interest in advanced concepts for controlling emissions of air toxics from coal-fired utility boilers. We are determining the feasibility of developing a biochemical process for the precombustion removal of substantial percentages of 13 inorganic hazardous air pollutant (HAP) precursors from coal. These HAP precursors are Sb, As, Be, Cd, Cr, Cl, Co, F, Pb, Hg, Mn, Ni, and Se. Although rapid physical coal cleaning is done routinely in preparation plants, biochemical processes for removal of HAP precursors from coal potentially offer advantages of deeper cleaning, more specificity, and less coal loss. Compared to chemical processes for coal cleaning, biochemical processes potentially offer lower costs and milder process conditions. Pyrite oxidizing bacteria, most notably Thiobacillusferrooxidans, are being evaluated in this project for their ability to remove HAP precursors from U.S. coals.

  4. Rapid synthesis of macrocycles from diol precursors

    DEFF Research Database (Denmark)

    Wingstrand, Magnus; Madsen, Charlotte Marie; Clausen, Mads Hartvig

    2009-01-01

    A method for the formation of synthetic macrocycles with different ring sizes from diols is presented. Reacting a simple diol precursor with electrophilic reagents leads to a cyclic carbonate, sulfite or phosphate in a single step in 25-60% yield. Converting the cyclization precursor to a bis-ele......-electrophilic iodide or aldehyde enables preparation of a cyclic sulfide and amine, respectively, the latter using a double reductive amination to induce ring closure....

  5. Acoustic precursor wave propagation in viscoelastic media.

    Science.gov (United States)

    Zhu, Guangran Kevin; Mojahedi, Mohammad; Sarris, Costas D

    2014-03-01

    Precursor field theory has been developed to describe the dynamics of electromagnetic field evolution in causally attenuative and dispersive media. In Debye dielectrics, the so-called Brillouin precursor exhibits an algebraic attenuation rate that makes it an ideal pulse waveform for communication, sensing, and imaging applications. Inspired by these studies in the electromagnetic domain, the present paper explores the propagation of acoustic precursors in dispersive media, with emphasis on biological media. To this end, a recently proposed causal dispersive model is employed, based on its interpretation as the acoustic counterpart of the Cole¿Cole model for dielectrics. The model stems from the fractional stress¿strain relation, which is consistent with the empirically known frequency power-law attenuation in viscoelastic media. It is shown that viscoelastic media described by this model, including human blood, support the formation and propagation of Brillouin precursors. The amplitude of these precursors exhibits a sub-exponential attenuation rate as a function of distance, actually being proportional to z(-p), where z is the distance traveled within the medium and 0.5

    precursors identified in this work facilitate the design of optimal waveforms for propagation in complex media, creating new possibilities for acoustic-pulse-based communication and imaging systems.

  6. Cockayne syndrome b maintains neural precursor function.

    Science.gov (United States)

    Sacco, Raffaele; Tamblyn, Laura; Rajakulendran, Nishani; Bralha, Fernando N; Tropepe, Vincent; Laposa, Rebecca R

    2013-02-01

    Neurodevelopmental defects are observed in the hereditary disorder Cockayne syndrome (CS). The gene most frequently mutated in CS, Cockayne Syndrome B (CSB), is required for the repair of bulky DNA adducts in transcribed genes during transcription-coupled nucleotide excision repair. CSB also plays a role in chromatin remodeling and mitochondrial function. The role of CSB in neural development is poorly understood. Here we report that the abundance of neural progenitors is normal in Csb(-/-) mice and the frequency of apoptotic cells in the neurogenic niche of the adult subependymal zone is similar in Csb(-/-) and wild type mice. Both embryonic and adult Csb(-/-) neural precursors exhibited defective self-renewal in the neurosphere assay. In Csb(-/-) neural precursors, self-renewal progressively decreased in serially passaged neurospheres. The data also indicate that Csb and the nucleotide excision repair protein Xpa preserve embryonic neural stem cell self-renewal after UV DNA damage. Although Csb(-/-) neural precursors do not exhibit altered neuronal lineage commitment after low-dose UV (1J/m(2)) in vitro, neurons differentiated in vitro from Csb(-/-) neural precursors that had been irradiated with 1J/m(2) UV exhibited defective neurite outgrowth. These findings identify a function for Csb in neural precursors. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Nozzle designs with pitch precursor ablatives

    Science.gov (United States)

    Blevins, H. R.; Bedard, R. J.

    1976-01-01

    Recent developments in carbon phenolic ablatives for solid rocket motor nozzles have yielded a pitch precursor carbon fiber offering significant raw material availability and cost saving advantages as compared to conventional rayon precursor material. This paper discusses the results of an experimental program conducted to assess the thermal performance and characterize the thermal properties of pitch precursor carbon phenolic ablatives. The end result of this program is the complete thermal characterization of pitch fabric, pitch mat, hybrid pitch/rayon fabric and pitch mat molding compound. With these properties determined an analytic capability now exists for predicting the thermal performance of these materials in rocket nozzle liner applications. Further planned efforts to verify material performance and analytical prediction procedures through actual rocket motor firings are also discussed.

  8. Ceramic fibers from Sol-Gel precursors

    Energy Technology Data Exchange (ETDEWEB)

    Glaubitt, W.; Sporn, D.; Jahn, R. [Fraunhofer Institut fuer Silicatforschung, Wuerzburg (Germany)

    1995-09-01

    Powderless methods for the preparation of continuously spirmable alumina, mullite, spinel, yttrium alumina garnet (YAG) and lead zirconium titanate (PZT) precursors are presented. The Al containing solutions are based on alcoholysis, carboxylation and hydrolysis reactions, which are described in detail. In addition, a synthesis route for the preparation of piezoelectric PZT long fibers has also been developed. This novel PZT precursor contains lead subcarboxylate and zirconium titanium oxohydroxocarboxylate. In all cases, continuously spinnable precursors which have been extruded with velocities up to 200 m/min, have been obtained. Gel fibers of several kilometer length could be drawn directly from sols. After drying, pyrolysis and sintering, each of the {alpha}-Al{sub 2}O{sub 3}, mullite. spinel, YAG and PZT, fibers have been obtained.

  9. Elicitation and precursor feeding influence phenolic acids ...

    African Journals Online (AJOL)

    Plant cell cultures have been industrially used for the synthesis of secondary metabolites. Different elicitors, [jasmonic acid (JA), salicylic acid (SA) and ethephone (E)] and precursors [shicimic acid (SH) and phenylalanine (PHE)] were independently used to enhance the synthesis of phenolics in suspension cultures of Vitis ...

  10. Biochemical Removal of HAP Precursors from Coal

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Gregory J

    1997-05-12

    Column biooxidation tests with Kentucky coal confirmed results of earlier shake flask tests showing significant removal from the coal of arsenic, selenium, cobalt, manganese, nickel and cadmium. Rates of pyrite biooxidation in Kentucky coal were only slightly more than half the rates found previously for Indiana and Pittsburgh coals. Removal of pyrite from Pittsburgh coal by ferric ion oxidation slows markedly as ferrous ions accumulate in solution, requiring maintenance of high redox potentials in processes designed for removal of pyrite and hazardous air pollutant (HAP) precursors by circulation of ferric solutions through coal. The pyrite oxidation rates obtained in these tests were used by Unifield Engineering to support the conceptual designs for alternative pyrite and HAP precursor bioleaching processes for the phase 2 pilot plant. Thermophilic microorganisms were tested to determine if mercury could be mobilized from coal under elevated growth temperatures. There was no evidence for mercury removal from coal under these conditions. However, the activity of the organisms may have liberated mercury physically. It is also possible that the organisms dissolved mercury and it readsorbed to the clay preferentially. Both of these possibilities are undergoing further testing. The Idaho National Engineering and Environmental Laboratory's (INEEL) slurry column reactor was operated and several batches of feed coal, product coal, waste solids and leach solutions were submitted to LBL for HAP precursor analysis. Results to date indicate significant removal of mercury, arsenic and other HAP precursors in the combined physical-biological process.

  11. Sol-gel precursors and products thereof

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  12. Conformal Dynamics of Precursors to Fracture

    OpenAIRE

    Barra, Felipe; Herrera, Mauricio; Procaccia, Itamar

    2002-01-01

    An exact integro-differential equation for the conformal map from the unit circle to the boundary of an evolving cavity in a stressed 2-dimensional solid is derived. This equation provides an accurate description of the dynamics of precursors to fracture when surface diffusion is important. The solution predicts the creation of sharp grooves that eventually lead to material failure via rapid fracture. Solutions of the new equation are demonstrated for the dynamics of an elliptical cavity and ...

  13. Calculations of precursor propagation in dispersive dielectrics.

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, Larry Donald

    2003-08-01

    The present study is a numerical investigation of the propagation of electromagnetic transients in dispersive media. It considers propagation in water using Debye and composite Rocard-Powles-Lorentz models for the complex permittivity. The study addresses this question: For practical transmitted spectra, does precursor propagation provide any features that can be used to advantage over conventional signal propagation in models of dispersive media of interest? A companion experimental study is currently in progress that will attempt to measure the effects studied here.

  14. PRECURSORS OF EARTHQUAKES: VLF SIGNALSIONOSPHERE IONOSPHERE RELATION

    Directory of Open Access Journals (Sweden)

    Mustafa ULAS

    2013-01-01

    Full Text Available lot of people have died because of earthquakes every year. Therefore It is crucial to predict the time of the earthquakes reasonable time before it had happed. This paper presents recent information published in the literature about precursors of earthquakes. The relationships between earthquakes and ionosphere are targeted to guide new researches in order to study further to find novel prediction methods.

  15. Microstructure of doped barium titanate prepared from polymeric precursors

    Directory of Open Access Journals (Sweden)

    Stojanovic, B. D.

    2002-02-01

    Full Text Available Barium titanate is used extensively as a dielectric in ceramic capacitors, particularly due to its high dielectric constant and low dielectric loss characteristics. It can be made semiconducting by addition of certain dopants and by proper modification of grains and grain boundary properties obtaining very interesting characteristics for various applications. The synthesis method and sintering regime have a strong influence on properties of obtained barium titanate ceramics. Doped barium titanate was prepared with Nb+5 and Y+3 ions as donor dopants, and with Mn+2 ions as acceptor dopant by polymeric precursors method. By this procedure nanosized powders were obtained after calcination. Sintering was performed in the temperature range of 1290ºC to 1380ºC. The microstructure of doped BaTiO3 was performed using scanning electron microscopy. The influence of dopants and sintering temperature on grain size was analysed.

    El titanato de bario se usa extensamente como dieléctrico en condensadores cerámicos, debido principalmente a su elevada constante dieléctrica y a sus bajas pérdidas dieléctricas. Puede hacerse semiconductor mediante la adición de ciertos dopantes y a través de modificaciones adecuadas de las propiedades de los granos y los bordes de grano se obtienen características muy interesantes para muchas aplicaciones. El método de síntesis y el régimen de sinterización tienen una fuerte influencia sobre las propiedades del titanato de bario cerámico. El titanato de bario dopado con Nb5+ y Y3+ como dopantes donores y con Mn2+ como dopante aceptor se preparó mediante el método de precursores poliméricos. Mediante este procedimiento se obtuvieron polvos nanométricos después de la etapa de calcinación. La sinterización se realizó en el intervalo de temperaturas entre 1290ºC y 1380ºC. La microestructura del BaTiO3 dopado se estudió usando microscopía electrónica de barrido. Se analizó la influencia de los

  16. Cellular kinetics of perivascular MSC precursors.

    Science.gov (United States)

    Chen, William C W; Park, Tea Soon; Murray, Iain R; Zimmerlin, Ludovic; Lazzari, Lorenza; Huard, Johnny; Péault, Bruno

    2013-01-01

    Mesenchymal stem/stromal cells (MSCs) and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

  17. Cellular Kinetics of Perivascular MSC Precursors

    Directory of Open Access Journals (Sweden)

    William C. W. Chen

    2013-01-01

    Full Text Available Mesenchymal stem/stromal cells (MSCs and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

  18. Ionospheric precursors for crustal earthquakes in Italy

    Directory of Open Access Journals (Sweden)

    L. Perrone

    2010-04-01

    Full Text Available Crustal earthquakes with magnitude 6.0>M≥5.5 observed in Italy for the period 1979–2009 including the last one at L'Aquila on 6 April 2009 were considered to check if the earlier obtained relationships for ionospheric precursors for strong Japanese earthquakes are valid for the Italian moderate earthquakes. The ionospheric precursors are based on the observed variations of the sporadic E-layer parameters (h'Es, fbEs and foF2 at the ionospheric station Rome. Empirical dependencies for the seismo-ionospheric disturbances relating the earthquake magnitude and the epicenter distance are obtained and they have been shown to be similar to those obtained earlier for Japanese earthquakes. The dependences indicate the process of spreading the disturbance from the epicenter towards periphery during the earthquake preparation process. Large lead times for the precursor occurrence (up to 34 days for M=5.8–5.9 tells about a prolong preparation period. A possibility of using the obtained relationships for the earthquakes prediction is discussed.

  19. Use of plankton-derived vitamin B1 precursors, especially thiazole-related precursor, by key marine picoeukaryotic phytoplankton.

    Science.gov (United States)

    Paerl, Ryan W; Bouget, Francois-Yves; Lozano, Jean-Claude; Vergé, Valérie; Schatt, Philippe; Allen, Eric E; Palenik, Brian; Azam, Farooq

    2017-03-01

    Several cosmopolitan marine picoeukaryotic phytoplankton are B1 auxotrophs requiring exogenous vitamin B1 or precursor to survive. From genomic evidence, representatives of picoeukaryotic phytoplankton (Ostreococcus and Micromonas spp.) were predicted to use known thiazole and pyrimidine B1 precursors to meet their B1 demands, however, recent culture-based experiments could not confirm this assumption. We hypothesized these phytoplankton strains could grow on precursors alone, but required a thiazole-related precursor other the well-known and extensively tested 4-methyl-5-thiazoleethanol. This hypothesis was tested using bioassays and co-cultures of picoeukaryotic phytoplankton and bacteria. We found that specific B1-synthesizing proteobacteria and phytoplankton are sources of a yet-to-be chemically identified thiazole-related precursor(s) that, along with pyrimidine B1 precursor 4-amino-5-hydroxymethyl-2-methylpyrimidine, can support growth of Ostreococcus spp. (also Micromonas spp.) without B1. We additionally found that the B1-synthesizing plankton do not require contact with picoeukaryotic phytoplankton cells to produce thiazole-related precursor(s). Experiments with wild-type and genetically engineered Ostreococcus lines revealed that the thiazole kinase, ThiM, is required for growth on precursors, and that thiazole-related precursor(s) accumulate to appreciable levels in the euphotic ocean. Overall, our results point to thiazole-related B1 precursors as important micronutrients promoting the survival of abundant phytoplankton influencing surface ocean production and biogeochemical cycling.

  20. Meat flavor precursors and factors influencing flavor precursors--A systematic review.

    Science.gov (United States)

    Khan, Muhammad Issa; Jo, Cheorun; Tariq, Muhammad Rizwan

    2015-12-01

    Flavor is the sensory impression sensed by taste and smell buds and is a leading factor determining the meat quality and purchasing decision of the consumer. Meat flavor is characteristic of volatiles produced as a result of reactions of non-volatile components that are induced thermally. The water soluble compounds having low molecular weight and meat lipids are important precursors of cooked meat flavor. The Maillard reaction, lipid oxidation, and vitamin degradation are leading reactions during cooking which develop meat flavor from uncooked meat with little aroma and bloody taste. The pre-slaughter and postmortem factors like animal breed, sex, age, feed, aging and cooking conditions contribute to flavor development of cooked meat. The objective of this review is to highlight the flavor chemistry, meat flavor precursors and factors affecting meat flavor precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Amorphous Alloy: Promising Precursor to Form Nanoflowerpot

    Directory of Open Access Journals (Sweden)

    Guo Lan

    2014-01-01

    Full Text Available Nanoporous copper is fabricated by dealloying the amorphous Ti2Cu alloy in 0.03 M HF electrolyte. The pore and ligament sizes of the nanoporous copper can be readily tailored by controlling the dealloying time. The as-prepared nanoporous copper provides fine and uniform nanoflowerpots to grow highly dispersed Au nanoflowers. The blooming Au nanoflowers in the nanoporous copper flowerpots exhibit both high catalytic activity and stability towards the oxidation of glucose, indicating that the amorphous alloys are ideal precursors to form nanoflowerpot which can grow functional nanoflowers.

  2. Convection and Mixing in Classical Novae Precursors

    Science.gov (United States)

    Dursi, L. J.; Calder, A. C.; Alexakis, A.; Truran, J. W.; Zingale, M.; Times, F. X.; Ricker, P. M.; Fryxell, B.; Olson, K.; Rosner, R.; MacNeice, P.

    2002-06-01

    To explain observed abundances from classical nova outbursts, and to help explain their energetics, nova models must incorporate a mechanism that will dredge up the heavier white dwarf material into the lighter accreted atmosphere. One proposed mechanism relies on the fluid motions from an early convective phase to do the mixing. We present recent work investigating two aspects of this mechanism. We examine results from two-dimensional simulations of classical nova precursor models that demonstrate the beginning of a convective phase during the `simmering' of a nova precursor. We use a new hydrostatic equilibrium hydrodynamics module recently developed for the adaptive-mesh code FLASH. The two-dimensional models are based on the one-dimensional models of Ami Glasner (Glasner et al. 1997), and were evolved with FLASH from a pre-convective state to the onset of convection. The onset of convection induces a velocity field near the C,O/H,He interface, which can then cause mixing through interactions with gravity waves. We show results from simulations of these wind-wave interactions, and estimate whether the `wind' caused by the convection could induce sufficient dredge-up to power a classical novae. This research has been supported by the US. Department of Energy under grant no. B341495 to the ASCI Flash Center at the University of Chicago

  3. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    Directory of Open Access Journals (Sweden)

    Peter Hesemann

    2014-04-01

    Full Text Available The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA, mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  4. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    Science.gov (United States)

    Hesemann, Peter; Nguyen, Thy Phung; Hankari, Samir El

    2014-01-01

    The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS) recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA), mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches. PMID:28788602

  5. Functional Nanoporous Polymers from Block Copolymer Precursors

    DEFF Research Database (Denmark)

    Guo, Fengxiao

    applications as, e.g., membranes for separation and purification, templates for nanostructured materials, sensors, substrates for catalysis, low dielectric constant materials, photonic materials, and depots for controlled drug delivery. The development of nanoporous polymers with well controlled pore wall......Abstract Self-assembly of block copolymers provides well-defined morphologies with characteristic length scales in the nanometer range. Nanoporous polymers prepared by selective removal of one block from self-assembled block copolymers offer great technological promise due to their many potential...... functionalities remains a great challenge due to the limitation of available polymer synthesis and the nanoscale confinement of the porous cavities. The main topic of this thesis is to develop methods for fabrication of functional nanoporous polymers from block copolymer precursors. A method has been developed...

  6. Ancient engineers' inventions precursors of the present

    CERN Document Server

    Rossi, Cesare

    2017-01-01

    This book describes the inventions and designs of ancient engineers who are the precursors of the present. The period ranges mainly from 300 B.C. to 1600 A.D. with several exceptions. Many of the oldest inventions are documented by archaeological finds, often very little known, mainly from Pompeii, Herculaneum and Stabiae and reveal a surprising modernity in their conception. Most of the inventions presented in the first four parts of the book were conceived up to the late Roman Empire and may be considered as milestones, each in their respective field. The fifth part concentrates on more recent centuries. The sixth part deals with some building construction techniques. Generally, for each of the presented inventions, three elements of research and reference are provided: written documents (the classics), iconic references (coins, bas-reliefs, etc.) and archaeological findings. The authors did not write this book for engineers only; hence they describe all the devices without assuming wide technical knowledge...

  7. Budget of ozone and precursors over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Roemer, M.G.M.; Bosman, R.; Thijsse, T.; Builtjes, P.J.H.; Esser, P. [IMW-TNO, Delft (Netherlands); Beck, J.P. [RIVM-LLO, Bilthoven (Netherlands); Vosbeek, M. [KEMA, Arnhem (Netherlands)

    1997-12-31

    A three dimensional model for the European boundary layer (the LOTOS model) was used to calculate the budget of ozone and precursors over Europe. For two summer months (July and August) in 1990 the net chemical production of ozone is about 21 Tg/m. By dry deposition 17 Tg/m is lost and transport accounts for a net export of 4 Tg/m into the free troposphere. Large differences in chemical ozone production occur for different regions in Europe. Though the ozone efficiency in terms of ozone produced per NO{sub x} molecule oxidised is much lower in western Europe than elsewhere in Europe the ozone chemically produced per unit area is the highest in western Europe due to the high NO{sub x} emission in this region. (orig.)

  8. The intramolecular click reaction using 'carbocontiguous' precursors.

    Science.gov (United States)

    Patil, Pravin C; Luzzio, Frederick A

    2017-07-20

    The synthesis and utilization of all carbon-chain 'carbocontiguous' azidoalkynyl precursors for an intramolecular click reaction is described. The substrates contain both azidoalkyl and ethynylmethyl groups which are conjoined by a 2-(phenylsulfonylmethyl)-4,5-diphenyloxazole lynchpin and are suitably disposed for ring closure. On promotion by copper salts, a number of cyclic click products having the 1,4-disubstituted endo-fused triazole component and the 4,5-diphenyloxazole component are obtained. In one case, removal of the phenylsulfonylmethyl group from the substrate prior to cyclization gave the 1,5-disubstituted exo-fused triazole. The utilization of CuSO4/sodium ascorbate system appears to be the optimal conditions for closure/cyclization and afforded the cyclized products in yields of 84-95%.

  9. Precursor conditions related to Zimbabwe's summer droughts

    Science.gov (United States)

    Nangombe, Shingirai; Madyiwa, Simon; Wang, Jianhong

    2018-01-01

    Despite the increasing severity of droughts and their effects on Zimbabwe's agriculture, there are few tools available for predicting these droughts in advance. Consequently, communities and farmers are more exposed, and policy makers are always ill prepared for such. This study sought to investigate possible cycles and precursor meteorological conditions prior to drought seasons that could be used to predict impending droughts in Zimbabwe. The Single Z-Index was used to identify and grade drought years between 1951 and 2010 according to rainfall severity. Spectral analysis was used to reveal the cycles of droughts for possible use of these cycles for drought prediction. Composite analysis was used to investigate circulation and temperature anomalies associated with severe and extreme drought years. Results indicate that severe droughts are more highly correlated with circulation patterns and embedded weather systems in the Indian Ocean and equatorial Pacific Ocean than any other area. This study identified sea surface temperatures in the average period June to August, geopotential height and wind vector in July to September period, and air temperature in September to November period as precursors that can be used to predict a drought occurrence several months in advance. Therefore, in addition to sea surface temperature, which was identified through previous research for predicting Zimbabwean droughts, the other parameters identified in this study can aid in drought prediction. Drought cycles were established at 20-, 12.5-, 3.2-, and 2.7-year cycles. The spectral peaks, 12.5, 3.2, and 2.7, had a similar timescale with the luni-solar tide, El Niño Southern Oscillation and Quasi Biennial Oscillation, respectively, and hence, occurrence of these phenomena have a possibility of indicating when the next drought might be.

  10. Precursors to glycogen in ovine fetuses

    Energy Technology Data Exchange (ETDEWEB)

    Levitsky, L.L.; Paton, J.B.; Fisher, D.E. (Univ. of Chicago, IL (USA))

    1988-11-01

    Postprandial hepatic glycogenesis in the adult animal is now felt to proceed largely through gluconeogenic pathways rather than directly from glucose. The ovine fetus, like the mature sheep, lacks specific hepatic glucokinase. Therefore, the authors examined the role of lactate as a fetal glycogenic precursor in seven chronically catheterized 125-day sheep fetuses. Fetuses were infused with L-(U-{sup 14}C)lactate and D-(3-{sup 3}H)glucose, while maternal glucose was maintained at 50 mg/dl. Mean fetal hepatic glycogen specific activity ({mu}Ci/mg {times} 10{sup 3}) was 0.82 {plus minus} 0.08 for {sup 14}C and 2.6 {plus minus} 0.4 for {sup 3}H, whereas fetal renal glycogen specific activity was 0.46 {plus minus} 0.22 for {sup 14}C and 0.78 {plus minus} 0.16 for {sup 3}H. In contrast, ({sup 14}C)glucose specific activity was undetectable in blood and mean ({sup 3}H)glucose specific activity was 8.9 {plus minus} 1.3 {mu}Ci/mg {times} 10{sup 3}. The least detectable specific activity of ({sup 14}C)glucose did not differ significantly from the ({sup 14}C)glycogen enrichment in liver, whereas ({sup 3}H)glucose specific activity was significantly greater than ({sup 3}H)glycogen enrichment. The authors conclude that glycogenesis from glucose is partly through the indirect gluconeogenic route and that lactate may be a glycogenic precursor in the ovine fetus.

  11. Preparation of boron nitride fiber by organic precursor method

    Directory of Open Access Journals (Sweden)

    Yingying Zhou

    Full Text Available In this paper, boron nitride polymer precursor was made by boric acid, melamine, twelve sodium alkyl sulfate as raw materials and pure water as medium which is heated to 70 °C. Boron nitride precursor polymer was soluble in formic acid solution. The boron nitride precursor can be electrostatically spun at the voltage in 23 kV and the distance between the positive and negative poles is 15 cm. The formed fiber is very uniform. The properties of the precursors were analyzed through electron microscope, infrared spectrum, X-ray and ultraviolet spectrum. The aim of the job is to got the precursor of BN and spun it. Keywords: Melamine, Boric acid, Boron nitride precursor, Electrostatic spinning

  12. Eruption precursors: Manifestations and strategies for detection

    Science.gov (United States)

    Poland, Michael; Pritchard, Matthew

    2017-04-01

    The past several decades have seen a rapid increase in volcano monitoring and modeling capabilities. Diverse arrays of instrument networks can detect a variety of pre-, co-, and post-eruptive phenomena, and remote sensing observations are available across a range of spatial, temporal, and spectral resolutions. A growing class of models, based on the physics of magmatic systems, are making use of these expanding datastreams, providing probabilistic assessments of such parameters as magma supply, volatile content, and eruption duration. To what extent, however, do these developments heighten our ability to identify eruption precursors? The advent of better data and new models provides an opportunity to reexamine our understanding of pre-eruption unrest, as well as our ability to detect and recognize it as such. An idealized model of the buildup to a volcanic eruption might include magma ascent from a deep source region and accumulation in the mid- to upper crust in the preceding months to years. The process might be manifested by surface inflation and deep long-period earthquakes, and accompanied by an increase in CO2 emissions. As magma continues to accumulate, distal volcano-tectonic earthquakes may result as stress builds on nearby faults, H2S emissions may increase as sulfur in a shallow reservoir is hydrolyzed by groundwater, and fumarole and spring temperatures may increase and show changes in chemistry. In the days to hours before an eruption, sudden changes in the rate and style of earthquakes (including repeating earthquakes and tremor) and deformation may occur as the magma reservoir ruptures and magma moves laterally or vertically. Phreatic eruptions might result as ascending magma comes into contact with groundwater, and SO2 emissions might increase as the path between the magma and surface dries out. How often does such a sequence actually occur? Relatively few volcanoes are comprehensively monitored prior to obvious expressions of unrest, so this is not

  13. Frog Swarms: Earthquake Precursors or False Alarms?

    Directory of Open Access Journals (Sweden)

    Rachel A. Grant

    2013-10-01

    Full Text Available In short-term earthquake risk forecasting, the avoidance of false alarms is of utmost importance to preclude the possibility of unnecessary panic among populations in seismic hazard areas. Unusual animal behaviour prior to earthquakes has been reported for millennia but has rarely been scientifically documented. Recently large migrations or unusual behaviour of amphibians have been linked to large earthquakes, and media reports of large frog and toad migrations in areas of high seismic risk such as Greece and China have led to fears of a subsequent large earthquake. However, at certain times of year large migrations are part of the normal behavioural repertoire of amphibians. News reports of “frog swarms” from 1850 to the present day were examined for evidence that this behaviour is a precursor to large earthquakes. It was found that only two of 28 reported frog swarms preceded large earthquakes (Sichuan province, China in 2008 and 2010. All of the reported mass migrations of amphibians occurred in late spring, summer and autumn and appeared to relate to small juvenile anurans (frogs and toads. It was concluded that most reported “frog swarms” are actually normal behaviour, probably caused by juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre

  14. Observations of Precursor Breakdown Prior to Intracloud Lightning Discharges

    Science.gov (United States)

    Rison, W.; Krehbiel, P. R.; Thomas, R. J.; Brown, M. F.

    2009-12-01

    Using the New Mexico Tech VHF Lightning Mapping Array (LMA) we have detected weak precursor discharges occurring up to a few tens of seconds before the initiation of normal polarity intracloud (IC) lightning discharges. With the very sensitive LMA installed at White Sands Missile Range (WSMR) in south central New Mexico, we observe low-power VHF precursor events in about 10% of lightning discharges. Most of the precursors occur within horizontal distances of about 200 meters of the locations of the initial LMA sources observed in the subsequent discharges, with altitudes about the same as the altitudes of the initial LMA sources. Most precursors consist of a single LMA source, indicating that the duration of the RF emission is less than the 80 μs time window of the WSMR LMA. Occasionally, a given precursor event lasts for up to 400 μs. For most discharges with precursors, only one precursor is observed, occurring anywhere from a few hundred milliseconds to 30 seconds before the discharge. For some flashes, more precursors are observed, several seconds apart. In a few cases, some of the precursor sources are several kilometers from the initial LMA source. In these cases, the leader channels of the ensuing discharge propagate from the flash initiation point to the horizontal locations of the distant precursors. The precursors apparently occur in the regions of the highest pre-discharge fields in the cell, indicating high field regions before the lightning discharge. The precursors are observed only at altitudes of about 8 to 10 km, corresponding to the region between the mid-level negative and upper positive storm charges. We have not observed precursors at altitudes in the 5 to 7 km range, corresponding to the region below the mid-level negative charge where CG discharges are initiated. The altitude dependence of the precursors may result from the fact that breakdown is easier to initiate at lower pressures. Because of RF emission restrictions at WSMR, the

  15. Precursors to Interstellar Shocks of Solar Origin

    Science.gov (United States)

    Gurnett, D. A.; Kurth, W. S.; Stone, E. C.; Cummings, A. C.; Krimigis, S. M.; Decker, R. B.; Ness, N. F.; Burlaga, L. F.

    2015-12-01

    On or about 2012 August 25, the Voyager 1 spacecraft crossed the heliopause into the nearby interstellar plasma. In the nearly three years that the spacecraft has been in interstellar space, three notable particle and field disturbances have been observed, each apparently associated with a shock wave propagating outward from the Sun. Here, we present a detailed analysis of the third and most impressive of these disturbances, with brief comparisons to the two previous events, both of which have been previously reported. The shock responsible for the third event was first detected on 2014 February 17 by the onset of narrowband radio emissions from the approaching shock, followed on 2014 May 13 by the abrupt appearance of intense electron plasma oscillations generated by electrons streaming outward ahead of the shock. Finally, the shock arrived on 2014 August 25, as indicated by a jump in the magnetic field strength and the plasma density. Various disturbances in the intensity and anisotropy of galactic cosmic rays were also observed ahead of the shock, some of which are believed to be caused by the reflection and acceleration of cosmic rays by the magnetic field jump at the shock, and/or by interactions with upstream plasma waves. Comparisons to the two previous weaker events show somewhat similar precursor effects, although differing in certain details. Many of these effects are very similar to those observed in the region called the "foreshock" that occurs upstream of planetary bow shocks, only on a vastly larger spatial scale.

  16. Histologic precursors of gastrointestinal tract malignancy.

    Science.gov (United States)

    Haber, Marian M

    2002-06-01

    Precursor lesions in the GIT include flat dysplasias, adenomas, dysplasia superimposed on nonneoplastic polyps, endocrine cell dysplasia, ACF, and condyloma accuminatum. Interobserver variability can be a problem in reporting dysplasia, and ancillary techniques including flow cytometry, image analysis, proliferation markers, and examination for p53 expression can help in this task. Squamous dysplasia seen in the esophagus and anus is graded on either a two-tiered or three-tiered system largely based on the extent of mucosal involvement. Glandular dysplasia is morphologically similar whether seen as an adenomatous polyp or within the setting of Barrett's esophagus, atrophic gastritis, or idiopathic inflammatory bowel disease. The distinction between LGD and HGD in glandular mucosa is based on the severity of cytologic and architectural distortion. Type I dysplasia is the classic adenomatous pattern seen most commonly and recognized by the presence of elongate hyperchromatic stratified nuclei. Type II, the nonadenomatous variant, contains vesicular nuclei and alteration in nuclear size and shape. Nonantral endocrine dysplasia in the stomach is seen in the setting of corporal predominant atrophic chronic gastritis and Zollinger-Ellison syndrome with Multiple Endocrine Neoplasia syndrome type I. Condyloma accuminatum is a HPV-related lesion most commonly seen in men practicing anal intercourse. Superimposed squamous dysplasia can be seen with HGD most frequently in the HIV-positive population. Recognition of the different classification systems of dysplasia, the most frequent settings in which these lesions are found, and their natural history is important for all practicing gastroenterologists and pathologists.

  17. Enzymatic synthesis of vitamin B6 precursor

    Directory of Open Access Journals (Sweden)

    Prlainović Nevena Ž.

    2013-01-01

    Full Text Available 3-Cyano-4-ethoxymethyl-6-methyl-2-pyridone is an important precursor in the synthesis of vitamin B6, obtained in the addition reaction between 2-cyanoacetamide and 1-ethoxy-2,4-pentanedione catalyzed by lipase from Candida rugosa (triacylglycerol ester hydrolases, EC 3.1.1.3. This work shows new experimental data and mathematical modeling of lipase catalyzed synthesis of 3-cyano-4-ethoxymethyl-6-methyl-2-pyridone, starting from 1-ethoxy-2,4-pentanedione and 2-cyanoacetamide. Kinetic measurements were done at 50 oC with enzyme concentration of 1.2 % w/v. Experimental results were fitted with two kinetic models: the ordered bi-ter and ping-pong bi-ter model, and the initial rates of the reaction were found to correlate best with a ping-pong bi-ter mechanism with inhibition by 2-cyanoacetamide. Obtained specificity constants indicated that lipase from C. rugosa had higher affinity towards 1-ethoxy-2,4-pentanedione and less bulky substrates. [Projekat Ministarstva nauke Republike Srbije, br. 172013, br. III 46010 and br. 172049

  18. Assimilation of NAD(+) precursors in Candida glabrata.

    Science.gov (United States)

    Ma, Biao; Pan, Shih-Jung; Zupancic, Margaret L; Cormack, Brendan P

    2007-10-01

    The yeast pathogen Candida glabrata is a nicotinamide adenine dinucleotide (NAD(+)) auxotroph and its growth depends on the environmental supply of vitamin precursors of NAD(+). C. glabrata salvage pathways defined in this article allow NAD(+) to be synthesized from three compounds - nicotinic acid (NA), nicotinamide (NAM) and nicotinamide riboside (NR). NA is salvaged through a functional Preiss-Handler pathway. NAM is first converted to NA by nicotinamidase and then salvaged by the Preiss-Handler pathway. Salvage of NR in C. glabrata occurs via two routes. The first, in which NR is phosphorylated by the NR kinase Nrk1, is independent of the Preiss-Handler pathway. The second is a novel pathway in which NR is degraded by the nucleosidases Pnp1 and Urh1, with a minor role for Meu1, and ultimately converted to NAD(+) via the nicotinamidase Pnc1 and the Preiss-Handler pathway. Using C. glabrata mutants whose growth depends exclusively on the external NA or NR supply, we also show that C. glabrata utilizes NR and to a lesser extent NA as NAD(+) sources during disseminated infection.

  19. Precursors to suicidality and violence on antidepressants

    DEFF Research Database (Denmark)

    Bielefeldt, Andreas Ø; Danborg, Pia B; Gøtzsche, Peter C

    2016-01-01

    OBJECTIVE: To quantify the risk of suicidality and violence when selective serotonin and serotonin-norepinephrine reuptake inhibitors are given to adult healthy volunteers with no signs of a mental disorder. DESIGN: Systematic review and meta-analysis. MAIN OUTCOME MEASURE: Harms related to suici......OBJECTIVE: To quantify the risk of suicidality and violence when selective serotonin and serotonin-norepinephrine reuptake inhibitors are given to adult healthy volunteers with no signs of a mental disorder. DESIGN: Systematic review and meta-analysis. MAIN OUTCOME MEASURE: Harms related...... to suicidality, hostility, activation events, psychotic events and mood disturbances. SETTING: Published trials identified by searching PubMed and Embase and clinical study reports obtained from the European and UK drug regulators. PARTICIPANTS: Double-blind, placebo-controlled trials in adult healthy volunteers...... that reported on suicidality or violence or precursor events to suicidality or violence. RESULTS: A total of 5787 publications were screened and 130 trials fulfilled our inclusion criteria. The trials were generally uninformative; 97 trials did not report the randomisation method, 75 trials did not report any...

  20. A fission-powered interstellar precursor mission

    Energy Technology Data Exchange (ETDEWEB)

    Lipinski, Ronald J.; Lenard, Roger X.; Wright, Steven A. [Sandia National Laboratories, MS-1146, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States)] West, John L. [Jet Propulsion Laboratory, MS-301-490, Pasadena, California 91109-8099 (United States)

    1999-01-01

    An {open_quotes}interstellar precursor mission{close_quotes} lays the groundwork for eventual interstellar exploration by studying the interstellar medium and by stretching technologies that have potential application for eventual interstellar exploration. The numerous scientific goals for such a mission include generating a 3-D stellar map of our galaxy, studying Kuiper-belt and Oort cloud objects, and observing distant objects using the sun{close_quote}s gravitational lens as the primary of an enormous telescope. System equations are developed for a space tug which propels a 2500-kg scientific payload to 550 astronomical units in about 20 years. The tug to transport this payload uses electric propulsion with an lsp of 15,000 seconds and a fission reactor with a closed Brayton cycle to generate the electricity. The optimal configuration may be to thrust for only about 6 years and then coast for the remaining 14 years. This spacecraft does not require any physics breakthroughs or major advances in technology. The fission power system can be engineered and built by drawing upon known technologies developed for related systems over the past 40 years. The tug system would eventually reach 1000 a.u in 33 years, and would have adequate power to relay large amounts of data throughout its journey. {copyright} {ital 1999 American Institute of Physics.}

  1. A Fission-Powered Interstellar Precursor Mission

    Energy Technology Data Exchange (ETDEWEB)

    Lenard, R.X.; Lipinski, R.J.; West, J.L.; Wright, S.A.

    1998-10-28

    An 'interstellar precursor mission' lays the groundwork for eventual interstellar exploration by studying the interstellar medium and by stretching technologies that have potential application for eventual interstellar exploration. The numerous scientific goals for such a mission include generating a 3-D stellar map of our galaxy, studying Kuiper-belt and Oort cloud objects, and observing distant objects using the sun's gravitational lens as the primary of an enormous telescope. System equations are developed for a space tug which propels a 2500-kg scientific payload to 550 astronomical units in about 20 years. The tug to transport this payload uses electric propulsion with an Isp of 15,000 seconds and a fission reactor with a closed Brayton cycle to genemte the electricity. The optimal configuration may be to thrust for only about 6 years and then coast for the remaining 14 pars. This spacecraft does not require any physics breakthroughs or major advances in technology. The fission power syslem can be engineered and built by drawing upon known technologies developed for relatgd systems over the past 40 years. The tug system would eventually reach 1000 a.u in 33 years, and would have adequate power to relay large amounts of data throughout its journey.

  2. Innate lymphoid cells, precursors and plasticity.

    Science.gov (United States)

    Gronke, Konrad; Kofoed-Nielsen, Michael; Diefenbach, Andreas

    2016-11-01

    Innate lymphoid cells (ILC) have only recently been recognized as a separate entity of the lymphoid lineage. Their subpopulations share common characteristics in terms of early development and major transcriptional circuitry with their related cousins of the T cell world. It is currently hypothesized that ILCs constitute an evolutionary older version of the lymphoid immune system. They are found at all primary entry points for pathogens such as mucosal surfaces of the lung and gastrointestinal system, the skin and the liver, which is the central contact point for pathogens that breach the intestinal barrier and enter the circulation. There, ILC contribute to the first line defense as well as to organ homeostasis. However, ILC are not only involved in classical defense tasks, but also contribute to the organogenesis of lymphoid organs as well as tissue remodeling and even stem cell regeneration. ILC may, therefore, implement different functions according to their emergence in ontogeny, their development and their final tissue location. We will review here their early development from precursors of the fetal liver and the adult bone marrow as well as their late plasticity in adaptation to their environment. Copyright © 2016 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.

  3. The Amyloid Precursor Protein Controls PIKfyve Function.

    Directory of Open Access Journals (Sweden)

    Zita Balklava

    Full Text Available While the Amyloid Precursor Protein (APP plays a central role in Alzheimer's disease, its cellular function still remains largely unclear. It was our goal to establish APP function which will provide insights into APP's implication in Alzheimer's disease. Using our recently developed proteo-liposome assay we established the interactome of APP's intracellular domain (known as AICD, thereby identifying novel APP interactors that provide mechanistic insights into APP function. By combining biochemical, cell biological and genetic approaches we validated the functional significance of one of these novel interactors. Here we show that APP binds the PIKfyve complex, an essential kinase for the synthesis of the endosomal phosphoinositide phosphatidylinositol-3,5-bisphosphate. This signalling lipid plays a crucial role in endosomal homeostasis and receptor sorting. Loss of PIKfyve function by mutation causes profound neurodegeneration in mammals. Using C. elegans genetics we demonstrate that APP functionally cooperates with PIKfyve in vivo. This regulation is required for maintaining endosomal and neuronal function. Our findings establish an unexpected role for APP in the regulation of endosomal phosphoinositide metabolism with dramatic consequences for endosomal biology and important implications for our understanding of Alzheimer's disease.

  4. Cystic precursors to invasive pancreatic cancer

    Science.gov (United States)

    Matthaei, Hanno; Schulick, Richard D.; Hruban, Ralph H.; Maitra, Anirban

    2011-01-01

    Improvements in the sensitivity and quality of cross-sectional imaging have led to increasing numbers of patients being diagnosed with cystic lesions of the pancreas. In parallel, clinical, radiological, pathological and molecular studies have improved the systems for classifying these cysts. Patients with asymptomatic serous cystic neoplasms can be managed conservatively with regular monitoring; however, the clinical management of patients with intraductal papillary mucinous neoplasms and mucinous cystic neoplasms is far more challenging, as it is difficult to determine whether these lesions will progress to malignancy. Fortunately, prospective studies have helped to establish that proposed clinical and radiological criteria (the Sendai guidelines) can be used to guide the care of patients with cystic lesions of the pancreas. Despite this progress in imaging and clinical guidelines, sensitive and specific tests have not yet been developed that can reliably predict the histology and biological properties of a cystic lesion. Such biomarkers are urgently needed, as noninvasive precursors of pancreatic cancer are curable, while the vast majority of invasive pancreatic adenocarcinomas are not. PMID:21383670

  5. Low Temperature Catalyst Assisted Pyrolysis of Polymer Precursors ...

    Indian Academy of Sciences (India)

    34

    the organic compounds into high-performance carbon. PAN is one of the most widely used polymer precursors for commercial carbon materials manufacturing including fibers, films and activated carbons [3-5]. To convert PAN into carbon, the precursor has to be first stabilized at. 250-300 °C in oxygen atmosphere followed ...

  6. 21 CFR 1308.47 - Control of immediate precursors.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Control of immediate precursors. 1308.47 Section 1308.47 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE SCHEDULES OF CONTROLLED SUBSTANCES Hearings § 1308.47 Control of immediate precursors. Pursuant to section 201(e) of the Act (21 U.S...

  7. Precursors to Aggression Are Evident by 6 Months of Age

    Science.gov (United States)

    Hay, Dale F.; Waters, Cerith S.; Perra, Oliver; Swift, Naomi; Kairis, Victoria; Phillips, Rebecca; Jones, Roland; Goodyer, Ian; Harold, Gordon; Thapar, Anita; van Goozen, Stephanie

    2014-01-01

    We tested the hypothesis that developmental precursors to aggression are apparent in infancy. Up to three informants rated 301 firstborn infants for early signs of anger, hitting and biting; 279 (93%) were assessed again as toddlers. Informants' ratings were validated by direct observation at both ages. The precursor behaviours were…

  8. Comparison studies of ozone precursors in Phoenix, Arizona

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, C.; Guyton, J.; Lee, C.P. [Arizona Dept. of Environmental Quality, Phoenix, AZ (United States); Parmar, S. [Atmospheric Analysis and Consulting Co., Ventura, CA (United States)

    1994-12-31

    This paper will present the comparison of the ozone precursors monitoring program for Phoenix, Arizona during 1992 and 1993. Specific details and methodologies will be presented involving collection of air samples and analysis of speciated measurements for reactive VOC and carbonyl precursors responsible for ozone formation. Quality control and quality assurance techniques will also be discussed.

  9. Geometrizing configurations. Heinrich Hertz and his mathematical precursors

    DEFF Research Database (Denmark)

    Lützen, Jesper

    1999-01-01

    A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics......A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics...

  10. A critical review of Electric Earthquake Precursors

    Directory of Open Access Journals (Sweden)

    F. Vallianatos

    2001-06-01

    Full Text Available The generation of transient electric potential prior to rupture has been demonstrated in a number of laboratory experiments involving both dry and wet rock specimens. Several different electrification effects are responsible for these observations, but how these may scale up co-operatively in large heterogeneous rock volumes, to produce observable macroscopic signals, is still incompletely understood. Accordingly, the nature and properties of possible Electric Earthquake Precursors (EEP are still inadequately understood. For a long time observations have been fragmentary, narrow band and oligo-parametric (for instance, the magnetic field was not routinely measured. In general, the discrimination of purported EEP signals relied on "experience" and ad hoc empirical rules that could be shown unable to guarantee the validity of the data. In consequence, experimental studies have produced a prolific variety of signal shape, complexity and duration but no explanation for the apparently indefinite diversity. A set of inconsistent or conflicting ideas attempted to explain such observations, including different concepts about the EEP source region (near the observer or at the earthquake focus and propagation (frequently assumed to be guided by peculiar geoelectric structure. Statistics was also applied to establish the "beyond chance" association between presumed EEP signals and earthquakes. In the absence of well constrained data, this approach ended up with intense debate and controversy but no useful results. The response of the geophysical community was scepticism and by the mid-90's, the very existence of EEP was debated. At that time, a major re-thinking of EEP research began to take place, with reformulation of its queries and objectives and refocusing on the exploration of fundamental concepts, less on field experiments. The first encouraging results began to appear in the last two years of the 20th century. Observation technologies are mature

  11. PRECOMBUSTION REMOVAL OF HAZARDOUS AIR POLLUTANT PRECURSORS

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2000-10-09

    In response to growing environmental concerns reflected in the 1990 Clean Air Act Amendment (CAAA), the United States Department of Energy (DOE) sponsored several research and development projects in late 1995 as part of an initiative entitled Advanced Environmental Control Technologies for Coal-Based Power Systems. The program provided cost-shared support for research and development projects that could accelerate the commercialization of affordable, high-efficiency, low-emission, coal-fueled electric generating technologies. Clean coal technologies developed under this program would serve as prototypes for later generations of technologies to be implemented in the industrial sector. In order to identify technologies with the greatest potential for commercial implementation, projects funded under Phase I of this program were subject to competitive review by DOE before being considered for continuation funding under Phase II. One of the primary topical areas identified under the DOE initiative relates to the development of improved technologies for reducing the emissions of air toxics. Previous studies have suggested that many of the potentially hazardous air pollutant precursors (HAPPs) occur as trace elements in the mineral matter of run-of-mine coals. As a result, these elements have the potential to be removed prior to combustion at the mine site by physical coal cleaning processes (i.e., coal preparation). Unfortunately, existing coal preparation plants are generally limited in their ability to remove HAPPs due to incomplete liberation of the mineral matter and high organic associations of some trace elements. In addition, existing physical coal cleaning plants are not specifically designed or optimized to ensure that high trace element rejections may be achieved.

  12. Study on Nuclear Accident Precursors Using AHP and BBN

    Directory of Open Access Journals (Sweden)

    Sujin Park

    2014-01-01

    Full Text Available Most of the nuclear accident reports used to indicate the implicit precursors which are not easily quantified as underlying factors. The current Probabilistic Safety Assessment (PSA is capable of quantifying the importance of accident causes in limited scope. It was, therefore, difficult to achieve quantifiable decision-making for resource allocation. In this study, the methodology which facilitates quantifying these precursors and a case study were presented. First, four implicit precursors have been obtained by evaluating the causality and hierarchy structure of various accident factors. Eventually, it turned out that they represent the lack of knowledge. After four precursors are selected, subprecursors were investigated and their cause-consequence relationship was implemented by Bayesian Belief Network (BBN. To prioritize the precursors, the prior probability is initially estimated by expert judgment and updated upon observations. The pair-wise importance between precursors is calculated by Analytic Hierarchy Process (AHP and the results are converted into node probability tables of the BBN model. Using this method, the sensitivity and the posterior probability of each precursor can be analyzed so that it enables making prioritization for the factors. We tried to prioritize the lessons learned from Fukushima accident to demonstrate the feasibility of the proposed methodology.

  13. Potencial del Agua del suelo

    Directory of Open Access Journals (Sweden)

    Bustamante Heliodoro

    1986-12-01

    Full Text Available La energía potencial del agua presenta diferencias de un punto del suelo a otro; esas diferencias son las que originan el movimiento del agua de acuerdo a la tendencia universal de la materia en el sentido de moverse de donde la energía potencial es mayor a donde dicha energía es menor. En el suelo el agua en consecuencia se mueve hacia donde su energía decrece hasta lograr su estado de equilibrio. Se desprende entonces que la cantidad de energía potencial absoluta contenida en el agua, no es importante por sí misma, sino por su relación con la energía en diferentes lugares dentro del suelo. El concepto Potencial de agua del suelo es un criterio para esta energía.

  14. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  15. Precursor Parameter Identification for Insulated Gate Bipolar Transistor (IGBT) Prognostics

    Data.gov (United States)

    National Aeronautics and Space Administration — Precursor parameters have been identified to enable development of a prognostic approach for insulated gate bipolar transistors (IGBT). The IGBT were subjected to...

  16. Precursor composites for oxygen dispersion hardened silver sheathed superconductor composites

    Science.gov (United States)

    Podtburg, Eric R.

    1999-01-01

    An oxide superconductor composite having improved texture and durability. The oxide superconductor composite includes an oxide superconductor phase substantially surrounded with/by a noble metal matrix, the noble metal matrix comprising a metal oxide in an amount effective to form metal oxide domains that increase hardness of the composite. The composite is characterized by a degree of texture at least 10% greater than a comparable oxide superconductor composite lacking metal oxide domains. An oxide superconducting composite may be prepared by oxidizing the precursor composite under conditions effective to form solute metal oxide domains within the silver matrix and to form a precursor oxide in the precursor alloy phase; subjecting the oxidized composite to a softening anneal under conditions effective to relieve stress within the noble metal phase; and converting the oxide precursor into an oxide superconductor.

  17. Terrorist Precursor Crimes: Issues and Options for Congress

    National Research Council Canada - National Science Library

    O'Neil, Siobhan

    2007-01-01

    ... not. Terrorist precursor crimes, offenses committed to facilitate a particular attack or promote a terrorist campaign's objectives, are thought to be often carried out far away from the primary theater...

  18. Solvothermal Molecular Precursor Routes to Semiconductor Film and Crystal Growth

    National Research Council Canada - National Science Library

    Gillan, Edward

    2002-01-01

    .... Reactions were run in toluene, THF, and under solvent free conditions. An in situ precursor synthesis and decomposition resulted in GaN nanoparticles from simple starting materials (GaCl(3) and NaN(3...

  19. Conditions for the differentiation of melanocyte-precursor cells from ...

    African Journals Online (AJOL)

    Conditions for the differentiation of melanocyte-precursor cells from human cord blood-derived mesenchymal stem cells. Jienny Lee, Jongsung Lee, Kyungbaeg Roh, Myeong-Ok Kim, Ju-Duck Kim, Deokhoon Park ...

  20. Optimization of precursor powders for manufacturing Bi-2223/Ag tapes

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C H [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Yoo, J M [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Ko, J W [Materials Engineering Department, Korea Institute of Machinery and Materials, 66 Sangnam-Dong, Changwon (Korea, Republic of); Chung, H S [Department of Molecular Science and Technology, Ajou University (Korea, Republic of); Qiao, G W [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China)

    2003-01-01

    The phase assemblage and particle sizes of precursor powders have been optimized in a sequence for fabricating Ag/BSCCO-2223 composite tapes. Firstly, an optimal calcination temperature was determined based on the experimental results. Then, the precursors calcined at the optimal temperature were ball-milled for different dwell times to obtain varied particle sizes. The effects of both the phase assemblages and particle sizes of the precursor powder on the phase formation, microstructure and transport J{sub c} of Bi-2223/Ag tapes have been investigated. The results show that the precursor phase assemblage has a large impact on the reaction routes, microstructure, and J{sub c} property. Meanwhile, a fine powder is beneficial for the grain growth, alignment, and J{sub c} enhancement in fully reacted tapes. The best J{sub c} was achieved in the tape made from the powder after optimizing the phase assemblage and particle size.

  1. Unconsumed precursors and couplers after formation of oxidative hair dyes

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Søsted, Heidi; Johansen, Jeanne Duus

    2006-01-01

    Contact allergy to hair dye ingredients, especially precursors and couplers, is a well-known entity among consumers having hair colouring done at home or at a hairdresser. The aim of the present investigation was to estimate consumer exposure to some selected precursors (p-phenylenediamine, toluene......-2,5-diamine) and couplers (3-aminophenol, 4-aminophenol, resorcinol) of oxidative hair dyes during and after hair dyeing. Concentrations of unconsumed precursors and couplers in 8 hair dye formulations for non-professional use were investigated, under the conditions reflecting hair dyeing. Oxidative...... hair dye formation in the absence of hair was investigated using 6 products, and 2 products were used for experimental hair dyeing. In both presence and absence of hair, significant amounts of unconsumed precursors and couplers remained in the hair dye formulations after final colour development. Thus...

  2. Optimization of precursor powders for manufacturing Bi-2223/Ag tapes

    Science.gov (United States)

    Jiang, C. H.; Yoo, J. M.; Ko, J. W.; Chung, H. S.; Qiao, G. W.

    2003-01-01

    The phase assemblage and particle sizes of precursor powders have been optimized in a sequence for fabricating Ag/BSCCO-2223 composite tapes. Firstly, an optimal calcination temperature was determined based on the experimental results. Then, the precursors calcined at the optimal temperature were ball-milled for different dwell times to obtain varied particle sizes. The effects of both the phase assemblages and particle sizes of the precursor powder on the phase formation, microstructure and transport Jc of Bi-2223/Ag tapes have been investigated. The results show that the precursor phase assemblage has a large impact on the reaction routes, microstructure, and Jc property. Meanwhile, a fine powder is beneficial for the grain growth, alignment, and Jc enhancement in fully reacted tapes. The best Jc was achieved in the tape made from the powder after optimizing the phase assemblage and particle size.

  3. On the possible involvement of bovine serum albumin precursor in ...

    Indian Academy of Sciences (India)

    biotin affinity chromatography and mass finger printing analysis technique, herein we report the identification of a 70 kDa size protein (bovine serum albumin precursor, BSAP) which binds strongly with lipoplexes and may play role in lipofection ...

  4. Supply of precursors for carotenoid biosynthesis in plants.

    Science.gov (United States)

    Rodríguez-Concepción, Manuel

    2010-12-01

    Carotenoids are isoprenoids of industrial and nutritional interest produced by all photosynthetic organisms, including plants. Too often, the metabolic engineering of plant carotenogenesis has been obstructed by our limited knowledge on how the endogenous pathway interacts with other related metabolic pathways, particularly with those involved in the production of isoprenoid precursors. However, recent discoveries are providing new insights into this field. All isoprenoids derive from prenyl diphosphate precursors. In the case of carotenoids, these precursors are produced predominantly by the methylerythritol 4-phosphate (MEP) pathway in plants. This review focuses on the progress in our understanding of how manipulation of the MEP pathway impacts carotenoid biosynthesis and on the discoveries underlining the central importance of coordinating the supply of MEP-derived precursors with the biosynthesis of carotenoids and other derived isoprenoids. Copyright © 2010 Elsevier Inc. All rights reserved.

  5. Depression Often a Precursor to Falls in Elderly People

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_165985.html Depression Often a Precursor to Falls in Elderly People ... 26, 2017 FRIDAY, May 26, 2017 (HealthDay News) -- Depression appears to raise the risk of falls in ...

  6. Ras signal triggers β-Amyloid Precursor Protein (APP) expression

    OpenAIRE

    Mora, Natalia; Santa Bárbara Ruiz, Paula; Ferreira, Nuno; Serras, Florenci

    2013-01-01

    It has recently been discovered that the Drosophila β-amyloid protein precursor like (Appl) gene, the ortholog of the human β-Amyloid Precursor Protein (APP) gene, is transcriptionally activated by receptor tyrosine kinase activity that involves Ras/MAPK signaling in vivo. This regulation is specifically controlled in photoreceptor neurons of the Drosophila retina. This suggests that some cases of Alzheimer disease, those which have been associated with high expression of the APP gene, may in...

  7. Synthesis of new diverse macrocycles from diol precursors

    DEFF Research Database (Denmark)

    Madsen, Charlotte Marie; Hansen, Martin; Thrane, Marie V.

    2010-01-01

    The formation of a library of diverse macrocycles with different ring sizes from two easily accessible building blocks is presented. Reacting diol precursors with electrophilic reagents lead to 17-membered sulfites and 19-membered malonates in 34–79% yield. Double-reductive amination of dialdehyde...... analogs of the diol precursors leads to 15-membered amines in yields ranging from 9 to 60%, reflecting large differences in reactivity based on steric environment....

  8. Structural organization of precursors of thermolysin-like proteinases.

    Science.gov (United States)

    Demidyuk, Ilya V; Gasanov, Eugene V; Safina, Dina R; Kostrov, Sergey V

    2008-09-01

    The primary structures of the full-length precursors of thermolysin-like proteinases (TLPs) were systemically analyzed. Structural comparison of the precursor amino-terminal regions (ATRs) removed during maturation allowed us to divide the family into two groups: peptidases with short (about 50 amino acids) and long (about 200 amino acids) ATRs. The accumulation of mutations in the ATRs of both types proved to correlate with that in the catalytic domains. No classical signal peptides were identified in the short ATRs, but they contained a conserved PPL-motif near the initiation methionine. The functional role of the short ATRs and PPL-motif is currently unclear. The C-terminal regions (CTRs) of TLP precursors, which are often removed during maturation, too, are found in about a half of precursors with long ATRs, but occur more rarely in precursors with short ATRs. CTRs in TLP precursors contain previously identified conserved domains typical for many other proteins and likely underlie the interaction with high molecular weight substrates.

  9. About the Purification Route of Ionic Liquid Precursors

    Directory of Open Access Journals (Sweden)

    Massimo De Francesco

    2017-03-01

    Full Text Available In this work a purification route of precursors for ionic liquids tailored to electrochemical energy storage systems is reported and described. The study was carried out on the N-butyl-N-methylpyrrolidinium bromide (PYR14Br precursor, which represents the intermediate product of the synthesis process of the N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonylimide (PYR14TFSI hydrophobic ionic liquid. The target is to develop an easy and cost-effective approach for efficiently purifying several kinds of ionic liquid precursors and determining their purity content. The PYR14Br precursor was synthesized through an eco-friendly preparation procedure, which requires water as the only processing solvent, and purified through sorbent materials, such as activated charcoal and alumina. The effect of the treatment/nature/content of sorbents and processing temperature/time was investigated. The impurity content was detected by UV-VIS spectrophotometry measurements. Additionally, a correlation between the measured absorbance and the content of impurities within the precursor was obtained. The purity level of the precursor was seen to play a key role in the electrochemical performance of the ionic liquids.

  10. del alcoholismo

    Directory of Open Access Journals (Sweden)

    Rodrigo Arias Duque

    2005-01-01

    Full Text Available Desde el punto de vista farmacológico, es importante comprender qué es el alcohol y cómo actúa en el organismo. No existe una causa simple, sino una interacción complicada de factores neuroquímicos, fisiológicos, psicológicos y sociales que originan y desarrollan esta grave enfermedad fármaco-dependiente. La acción psicofisiológica y farmacodinámica del alcohol es fundamentalmente depresiva, por la reducción de la transmisión sináptica en el sistema nervioso humano. Es un hecho conocido que el consumo excesivo de alcohol causa una disfunción aguda y crónica del cerebro, produciendo trastornos en el sistema nervioso central, presentando alteraciones en la memoria y en las funciones intelectuales como cálculo, comprensión y aprendizaje. A nivel hepático tiene lugar, en su mayoría, el metabolismo del alcohol, produciéndose un hígado graso alcohólico, aumentando el tamaño, terminando en necrosis e inflamación grave del hígado; esto se llama hepatitis alcohólica, y si se sigue consumiendo alcohol se desarrollará la cirrosis. El alcohol también ha estado relacionado con alteraciones del miocardio; se ha constatado en animales de experimentación sanos que tanto la velocidad de contracción del músculo cardiaco y su máxima tensión disminuyen en presencia del alcohol, como consecuencia, la fuerza de cada contracción y el aumento de presión en el ventrículo izquierdo son menores, perdiendo eficacia el corazón como bomba.

  11. Procedimiento de preparación de la forma metalosilicato de materiales tipo-MWW utilizando materiales deslaminados como precursores y su uso

    OpenAIRE

    Corma, Avelino; Moliner Marín, Manuel

    2012-01-01

    La presente invención se refiere a un proceso de síntesis de la forma metalosilicato de materiales tipo-MWW que comprende, al menos, los siguientes pasos: i) Preparación del precursor MWW pura sílice calentando una mezcla que comprende, al menos, un compuesto orgánico que actúa como agente director de estructura orgánico (ADEO), al menos una fuente de silicio y agua, entre otros compuestos que puedan ser necesarios (como por ejemplo aniones fluoruro); seguido de la recuperación del sólido...

  12. Experimental analysis of precursors to severe problem behavior.

    Science.gov (United States)

    Fritz, Jennifer N; Iwata, Brian A; Hammond, Jennifer L; Bloom, Sarah E

    2013-01-01

    Some individuals engage in both mild and severe forms of problem behavior. Research has shown that when mild behaviors precede severe behaviors (i.e., the mild behaviors serve as precursors), they can (a) be maintained by the same source of reinforcement as severe behavior and (b) reduce rates of severe behavior observed during assessment. In Study 1, we developed an objective checklist to identify precursors via videotaped trials for 16 subjects who engaged in problem behavior and identified at least 1 precursor for every subject. In Study 2, we conducted separate functional analyses of precursor and severe problem behaviors for 8 subjects, and obtained correspondence between outcomes in 7 cases. In Study 3, we evaluated noncontingent reinforcement schedule thinning plus differential reinforcement of alternative behavior to reduce precursors, increase appropriate behavior, and maintain low rates of severe behavior during 3 treatment analyses for 2 subjects. Results showed that this treatment strategy was effective for behaviors maintained by positive and negative reinforcement. © Society for the Experimental Analysis of Behavior.

  13. Quantification of erythroid and granulocytic precursor cells in plateletpheresis residues

    Energy Technology Data Exchange (ETDEWEB)

    Abboud, C.N.; Brennan, J.K.; Lichtman, M.A.; Nusbacher, J.

    1978-01-01

    Mononuclear cell fractions of human blood and plateletpheresis residues were compared for their content of hemopoietic precursor cells. Erythroid burst-forming units (BFU-E) averaged 560 +- 130 per ml of blood and granulocyte--monocyte colony forming units (CFU-C) averaged 240 +- 90 per ml blood. Estimates based on a blood volume of 7% of body weight indicate that the total blood pools of BFU-E and CFU-C are about 3.5 x 10/sup 6/ and 1.5 x 10/sup 6/ cells respectively. Sequential studies were performed over 3 days following one plateletpheresis in 4 donors. CFU-C and BFU-E approximately doubled between 48 and 72 hours after a plateletpheresis. During this time there was no significant alteration in the percent of null, T or B lymphocytes in blood. Thus, plateletpheresis appears to lead to a mobilization of precursor cells, which results in a transient increase in their concentration in blood. Therefore, pheresis 48 to 72 hours after an initial short-term procedure could harvest much larger numbers of precursor cells. Moreover, such techniques would put blood precursor cell content of plateletpheresis residues within reach of the precursor cell content in the volume of human marrow used for transplantation.

  14. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy.

    Directory of Open Access Journals (Sweden)

    Daniel Rodríguez-Martínez

    Full Text Available Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE, a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80% and yield (>70%. Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies.

  15. Anise oil as para-methoxyamphetamine (PMA) precursor.

    Science.gov (United States)

    Waumans, Dieter; Bruneel, Noël; Tytgat, Jan

    2003-04-23

    These days, MDMA is one of the most popular drugs of abuse. Due to its illegality, MDMA and its chemical precursors are watched by governmental organizations in many countries. To avoid conflicts with legal instances, underground chemists have tried to market several new unregulated amphetamine analogues, such as 4-MTA. Para-methoxyamphetamine (PMA), on the other hand, is regulated by law but its precursors are easily obtained since they are cheap and unwatched. This article presents such a case, namely the large scale synthesis of PMA using anethole, a main constituent of anise oil, as precursor. Anethole has been converted to its phenyl acetone analogue via peracid oxidation, while PMA itself has been synthesized using this ketone as precursor in the Leuckart synthesis. The synthesis of PMA using anethole as starting product has been investigated applying GC/MS and GC-HSPME/MS techniques, hereby discovering new specific (4-methoxyphenol) and already identified synthesis impurities (4-methyl-5-(4-methoxyphenyl)pyrimidine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzyl methyl ketimine, 1-(4-methoxyphenyl)-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, 1-(4-methoxyphenyl)-N-methyl-N-(2-(4-methoxyphenyl)-1-methylethyl-2-propanamine, N-(beta-4-methoxyphenylisopropyl)-4-methoxybenzaldimine). The new impurity 4-methoxyphenol is specific for the application of a peracid oxidation method where anethole is used as precursor.

  16. Thioamides as false melanin precursors. Studies in murine melanomas

    Energy Technology Data Exchange (ETDEWEB)

    Olander, K.; Larsson, B.; Dencker, L. (Department of Toxicology, University of Uppsala, Sweden)

    1983-01-01

    Melanotic melanomas show a high rate of melanin synthesis. Foreign substances that are accepted as precursors in the formation of melanin may therefore be useful in the diagnosis and therapy of malignant melanotic melanomas, if labelled with suitable radionuclides. We have earlier reported that 2-thiouracil is incorporated in melanotic melanomas, apparently as a false melanin precursor. In the present study it is shown that methimazole and 5-iodo-2-thiouracil are as well accepted as melanin precursors. 5-Iodo-2-thiouracil is of special interest, since iodine has many clinically useful radioisotopes. The chemical properties that characterize substances which are incorporated as false precursors into melanin are discussed. A free sulfur ligand of the thioamides (2-thiouracil, 5-iodo-2-thiouracil, methimazole and thiourea are all incorporated into melanin) seems to be essential and the link between these substances and the melanin. Uracil (which lacks sulfur) and 2-benzylthiouracil (where the sulfur is blocked with a benzyl group) do not attach to melanin. Our conclusion therefore is that the thioureylene structure is the smallest common molecular fragment of the false melanin precursors.

  17. Cryopreservation of GABAergic Neuronal Precursors for Cell-Based Therapy

    Science.gov (United States)

    2017-01-01

    Cryopreservation protocols are essential for stem cells storage in order to apply them in the clinic. Here we describe a new standardized cryopreservation protocol for GABAergic neural precursors derived from the medial glanglionic eminence (MGE), a promising source of GABAergic neuronal progenitors for cell therapy against interneuron-related pathologies. We used 10% Me2SO as cryoprotectant and assessed the effects of cell culture amplification and cellular organization, as in toto explants, neurospheres, or individualized cells, on post-thaw cell viability and retrieval. We confirmed that in toto cryopreservation of MGE explants is an optimal preservation system to keep intact the interneuron precursor properties for cell transplantation, together with a high cell viability (>80%) and yield (>70%). Post-thaw proliferation and self-renewal of the cryopreserved precursors were tested in vitro. In addition, their migration capacity, acquisition of mature neuronal morphology, and potency to differentiate into multiple interneuron subtypes were also confirmed in vivo after transplantation. The results show that the cryopreserved precursor features remained intact and were similar to those immediately transplanted after their dissection from the MGE. We hope this protocol will facilitate the generation of biobanks to obtain a permanent and reliable source of GABAergic precursors for clinical application in cell-based therapies against interneuronopathies. PMID:28122047

  18. Subcellular Distribution of Glutathione Precursors in Arabidopsis thaliana

    Science.gov (United States)

    Koffler, Barbara Eva; Maier, Romana; Zechmann, Bernd

    2011-01-01

    Abstract Glutathione is an important antioxidant and has many important functions in plant development, growth and defense. Glutathione synthesis and degradation is highly compartment-specific and relies on the subcellular availability of its precursors, cysteine, glutamate, glycine and γ-glutamylcysteine especially in plastids and the cytosol which are considered as the main centers for glutathione synthesis. The availability of glutathione precursors within these cell compartments is therefore of great importance for successful plant development and defense. The aim of this study was to investigate the compartment-specific importance of glutathione precursors in Arabidopsis thaliana. The subcellular distribution was compared between wild type plants (Col-0), plants with impaired glutathione synthesis (glutathione deficient pad2-1 mutant, wild type plants treated with buthionine sulfoximine), and one complemented line (OE3) with restored glutathione synthesis. Immunocytohistochemistry revealed that the inhibition of glutathione synthesis induced the accumulation of the glutathione precursors cysteine, glutamate and glycine in most cell compartments including plastids and the cytosol. A strong decrease could be observed in γ-glutamylcysteine (γ-EC) contents in these cell compartments. These experiments demonstrated that the inhibition of γ-glutamylcysteine synthetase (GSH1) – the first enzyme of glutathione synthesis – causes a reduction of γ-EC levels and an accumulation of all other glutathione precursors within the cells. PMID:22050910

  19. Fluid Mechanics of Lean Blowout Precursors in Gas Turbine Combustors

    Directory of Open Access Journals (Sweden)

    T. M. Muruganandam

    2012-03-01

    Full Text Available Understanding of lean blowout (LBO phenomenon, along with the sensing and control strategies could enable the gas turbine combustor designers to design combustors with wider operability regimes. Sensing of precursor events (temporary extinction-reignition events based on chemiluminescence emissions from the combustor, assessing the proximity to LBO and using that data for control of LBO has already been achieved. This work describes the fluid mechanic details of the precursor dynamics and the blowout process based on detailed analysis of near blowout flame behavior, using simultaneous chemiluminescence and droplet scatter observations. The droplet scatter method represents the regions of cold reactants and thus help track unburnt mixtures. During a precursor event, it was observed that the flow pattern changes significantly with a large region of unburnt mixture in the combustor, which subsequently vanishes when a double/single helical vortex structure brings back the hot products back to the inlet of the combustor. This helical pattern is shown to be the characteristic of the next stable mode of flame in the longer combustor, stabilized by double helical vortex breakdown (VBD mode. It is proposed that random heat release fluctuations near blowout causes VBD based stabilization to shift VBD modes, causing the observed precursor dynamics in the combustor. A complete description of the evolution of flame near the blowout limit is presented. The description is consistent with all the earlier observations by the authors about precursor and blowout events.

  20. Influence of the Precursor on Cerium Distribution over Alumina

    Science.gov (United States)

    Appel, Lucia G.; Appel, Lucia G.; Eon, J. G.; Schmal, M.

    1997-09-01

    The Ce/Al2O3 catalysts were prepared with Ce(NO3)3, (NH4)2Ce(NO3)6 and with cerium acethylacetonate precursors over alumina, by impregnation and grafting, respectively. Results have shown that the CeO2 surface area of the catalysts with the nitrate precursors is very similar but much higher on the catalysts with the acethylacetonate after grafting. The reducibility of this catalyst is better than of the catalysts with the nitrate precursor. TPR results indicate a reduction of CeO2, the formation of CeAlO3 and Ce2O3. The experimental condition employed here allows to attain saturation over alumina which is probably due to steric effects of the Ce(Acet)3 molecules.

  1. Thin film solar cells by selenization sulfurization using diethyl selenium as a selenium precursor

    Science.gov (United States)

    Dhere, Neelkanth G.; Kadam, Ankur A.

    2009-12-15

    A method of forming a CIGSS absorber layer includes the steps of providing a metal precursor, and selenizing the metal precursor using diethyl selenium to form a selenized metal precursor layer (CIGSS absorber layer). A high efficiency solar cell includes a CIGSS absorber layer formed by a process including selenizing a metal precursor using diethyl selenium to form the CIGSS absorber layer.

  2. Culturas del Mundo

    DEFF Research Database (Denmark)

    Benwell, Ann Fenger; Costa, Alberto; Waehle, Espen

    2006-01-01

    ’Culturas del mundo. Colecciones del Museo Nacional de Dinamarca’ with Ann Fenger Benwell in Culturas del Mundo. Colecciones del Museo Nacional de Dinamarca, ed. Silvia Sauquet, Fundación "la Caixa", Barcelona 2006, pp. 31-39......’Culturas del mundo. Colecciones del Museo Nacional de Dinamarca’ with Ann Fenger Benwell in Culturas del Mundo. Colecciones del Museo Nacional de Dinamarca, ed. Silvia Sauquet, Fundación "la Caixa", Barcelona 2006, pp. 31-39...

  3. Isolation of Oct4-expressing extraembryonic endoderm precursor cell lines.

    Directory of Open Access Journals (Sweden)

    Bisrat G Debeb

    Full Text Available BACKGROUND: The extraembryonic endoderm (ExEn defines the yolk sac, a set of membranes that provide essential support for mammalian embryos. Recent findings suggest that the committed ExEn precursor is present already in the embryonic Inner Cell Mass (ICM as a group of cells that intermingles with the closely related epiblast precursor. All ICM cells contain Oct4, a key transcription factor that is first expressed at the morula stage. In vitro, the epiblast precursor is most closely represented by the well-characterized embryonic stem (ES cell lines that maintain the expression of Oct4, but analogous ExEn precursor cell lines are not known and it is unclear if they would express Oct4. METHODOLOGY/PRINCIPAL FINDINGS: Here we report the isolation and characterization of permanently proliferating Oct4-expressing rat cell lines ("XEN-P cell lines", which closely resemble the ExEn precursor. We isolated the XEN-P cell lines from blastocysts and characterized them by plating and gene expression assays as well as by injection into embryos. Like ES cells, the XEN-P cells express Oct4 and SSEA1 at high levels and their growth is stimulated by leukemia inhibitory factor, but instead of the epiblast determinant Nanog, they express the ExEn determinants Gata6 and Gata4. Further, they lack markers characteristic of the more differentiated primitive/visceral and parietal ExEn stages, but exclusively differentiate into these stages in vitro and contribute to them in vivo. CONCLUSIONS/SIGNIFICANCE: Our findings (i suggest strongly that the ExEn precursor is a self-renewable entity, (ii indicate that active Oct4 gene expression (transcription plus translation is part of its molecular identity, and (iii provide an in vitro model of early ExEn differentiation.

  4. Generation of Vibrationally Excited HCP from a Stable Synthetic Precursor

    Science.gov (United States)

    Hull, Alexander W.; Jiang, Jun; Erickson, Trevor J.; Womack, Carrie; Nava, Matthew; Cummins, Christopher; Field, Robert W.

    2015-06-01

    HCP belongs to a class of reactive small molecules with much interest to spectroscopists. It bears certain similarities to HCN, including a strong {A}(bent) - {X}(linear) ultraviolet transition, associated with the HCP-HPC isomerization pathway. HCP has traditionally been generated by the in situ reaction of PH_3 and acetylene. In this talk, we will discuss a recently developed synthetic precursor molecule, 1,1-((triphenylphosphoranylidene)methyl)-9,10-phosphanoanthracene. At temperatures above 200 degrees Celsius, this precursor is thought to release HCP in a vibrationally excited state. We will present preliminary spectra on this system obtained by LIF and chirped pulse millimeter wave spectroscopy.

  5. Differentiation of Mouse Embryonic Stem Cells into Ventral Foregut Precursors

    DEFF Research Database (Denmark)

    Rothová, Michaela; Hölzenspies, Jurriaan J; Livigni, Alessandra

    2016-01-01

    Anterior definitive endoderm (ADE), the ventral foregut precursor, is both an important embryonic signaling center and a unique multipotent precursor of liver, pancreas, and other organs. Here, a method is described for the differentiation of mouse embryonic stem cells (mESCs) to definitive...... endoderm with pronounced anterior character. ADE-containing cultures can be produced in vitro by suspension (embryoid body) culture or in a serum-free adherent monolayer culture. ESC-derived ADE cells are committed to endodermal fates and can undergo further differentiation in vitro towards ventral foregut...

  6. Non-PGM cathode catalysts for fuel cell application derived from heat treated heteroatomic amines precursors

    Science.gov (United States)

    Serov, Alexey; Halevi, Barr; Artyushkova, Kateryna; Atanassov, Plamen B; Martinez, Ulises A

    2017-04-25

    A method of preparing M-N--C catalysts utilizing a sacrificial support approach and inexpensive and readily available polymer precursors as the source of nitrogen and carbon is disclosed. Exemplary polymer precursors include non-porphyrin precursors with no initial catalytic activity. Examples of suitable non-catalytic non-porphyrin precursors include, but are not necessarily limited to low molecular weight precursors that form complexes with iron such as 4-aminoantipirine, phenylenediamine, hydroxysuccinimide, ethanolamine, and the like.

  7. Carbon molecular sieve membranes prepared from porous fiber precursor

    NARCIS (Netherlands)

    Barsema, J.N.; van der Vegt, N.F.A.; Koops, G.H.; Wessling, Matthias

    2002-01-01

    Carbon molecular sieve (CMS) membranes are usually prepared from dense polymeric precursors that already show intrinsic gas separation properties. The rationale behind this approach is that the occurrence of any kind of initial porosity will deteriorate the final CMS performance. We will show that

  8. Do glycine-extended hormone precursors have clinical significance?

    DEFF Research Database (Denmark)

    Rehfeld, Jens Frederik

    2014-01-01

    and clinical effects of glycine-extended precursors for most other amidated hormones than gastrin and cholecystokinin (CCK). The idea of glycine-extended peptides as independent messengers was interesting. But clinical science has to move ahead from ideas that cannot be supported at key points after decades...

  9. Students' Perception of Continuous Assessment as a Precursor to ...

    African Journals Online (AJOL)

    Using student test to analysed the data, results indicated that there is significant difference between the perception of students from highly educated parents and those from low education homes to Continuous Assessment as a precursor to academic performance; here is significant difference between the perception of male ...

  10. Uche Okeke as A Precursor of Contemporary Nigerian Art Education

    African Journals Online (AJOL)

    user

    2013-07-07

    Jul 7, 2013 ... Introduction. The history of art Education in Nigeria is still rather inadequately and ... who made woodcarvings and furniture in his time, (Nwanna, 2004). Okonkwo & Akhogba: Uche Okeke as a Precursor of Contemporary Nigerian Art. Education .... visual art section, Refugee Affairs Committee. Experiment ...

  11. A study on precursors leading to geomagnetic storms using artificial ...

    Indian Academy of Sciences (India)

    Space weather prediction involves advance forecasting of the magnitude and onset time of major geomag- netic storms on Earth. In this paper, we discuss the development of an artificial neural network-based model to study the precursor leading to intense and moderate geomagnetic storms, following halo coronal.

  12. Production of jet fuel precursor monoterpenoids from engineered Escherichia coli

    DEFF Research Database (Denmark)

    Mendez-Perez, Daniel; Alonso-Gutierrez, Jorge; Hu, Qijun

    2017-01-01

    pathway. Monoterpene production at high levels required not only optimization of GPP production but also a basal level of FPP to maintain growth. The optimized strains produced two jet fuel precursor monoterpenoids 1,8-cineole and linalool at the titer of 653mg/L and 505mg/L, respectively, in batch...

  13. Precursors to numeracy in kindergartners with specific language impairment

    NARCIS (Netherlands)

    Kleemans, M.A.J.; Segers, P.C.J.; Verhoeven, L.T.W.

    2011-01-01

    The present study investigated to what extent children with specific language impairment (SLI) differ in their early numeracy skills, when compared to normal language achieving (NLA) children. It was also explored which precursors were related to the early numeracy skills in both groups. Sixty-one

  14. The miR-10 microRNA precursor family

    DEFF Research Database (Denmark)

    Tehler, Disa; Høyland-Kroghsbo, Nina Molin; Lund, Anders H

    2011-01-01

    The miR-10 microRNA precursor family encodes a group of short non-coding RNAs involved in gene regulation. The miR-10 family is highly conserved and has sparked the interest of many research groups because of the genomic localization in the vicinity of, coexpression with and regulation of the Hox...

  15. A study on precursors leading to geomagnetic storms using artificial ...

    Indian Academy of Sciences (India)

    Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagneticstorms on Earth. In this paper, we discuss the development of an artificial neural network-basedmodel to study the precursor leading to intense and moderate geomagnetic storms, following halo coronalmass ...

  16. Use of Internet Facilities and Metadata as Precursors to Electronic ...

    African Journals Online (AJOL)

    The study examined use of internet facilities and metadata as precursors to electronic resource cataloguing in selected academic libraries in South-West Nigeria. Six University libraries were randomly selected. One hundred (100) respondents comprising current cataloguers and those who had worked as cataloguers were ...

  17. College Student Stress: A Predictor of Eating Disorder Precursor Behaviors

    Science.gov (United States)

    Shelton, Virginia L.; Valkyrie, Karena T.

    2010-01-01

    Eating disorders are compulsive behaviors that can consume a person's life to the point of becoming life threatening. Previous research found stress associated with eating disorders. College can be a stressful time. If stress predicted precursor behaviors to eating disorders, then counselors would have a better chance to help students sooner. This…

  18. Observations on the Influence of Precursor Conformations on Macrocyclization Reactions

    DEFF Research Database (Denmark)

    Hammershøj, Peter; Beldring, Klavs; Nielsen, Anders R.

    2016-01-01

    macrocyclization to afford a mixture of diastereomeric sulfites, subjection of the other precursor to identical reaction conditions resulted in the isolation of the linear dichloride. We hypothesize that there is a difference in the ability of the two molecules to adopt a conformation that is germane...

  19. Measurement of excitation energy of neutron-rich precursor fragments

    Science.gov (United States)

    Mosby, Michelle Anthea

    Projectile fragmentation forms the basis for beam production at radioactive beam facilities such as the National Superconducting Cyclotron Laboratory (NSCL), yet uncertainties remain about the specifics of the production mechanism. For example, very little is known about the excitation energy of the precursors of the observed final fragments. In the present work, isotopes of sodium, neon, and fluorine produced in the fragmentation of a 32 Mg beam at 86 MeV/nucleon in a beryllium target, ranging in mass loss from DeltaA = 3--12, were observed and the coincident neutrons were detected using the Modular Neutron Array (MoNA). Neutron hit multiplicity in MoNA was compared to output from the statistical evaporation model PACE which was passed through a GEANT4 simulation to account for detector response with a X2v analysis. The neutron hit multiplicity distributions were used to determine the mass loss and excitation energy of the precursor fragments created in the fast step of the reaction. The mass loss and excitation energy were compared to abrasion/ablation models and an internuclear cascade model, ISABEL. For sodium and neon observed fragments, a single precursor mass was found, with a wide range of high excitation energies, up to 60 MeV. Observed fluorine isotopes were also found to have high excitation energies, ranging from 40--80 MeV, but with some variation in precursor mass.

  20. The isoprenoid-precursor dependence of Plasmodium spp

    NARCIS (Netherlands)

    van der Meer, Jan-Ytzen; Hirsch, Anna K. H.

    2012-01-01

    Due to the increase in resistance of Plasmodium spp. against available antimalarials, there is a need for new, effective and innovative drugs. The non-mevalonate pathway for the biosynthesis of the universal isoprenoid precursors, which is absent in humans, is suggested as an attractive source of

  1. Manganite perovskite ceramics, their precursors and methods for forming

    Science.gov (United States)

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  2. Intermediate obtained from photoionization, serving as precursor for ...

    African Journals Online (AJOL)

    In this article, we have introduced an intermediate benzyl carbocation (formed as a result of photoionization) which serves as precursor for the synthesis of Schiff's base. Lifetimes of many carbocations were determined from our laboratory. During the determination of the lifetimes, our endeavor was to obtain a carbocation ...

  3. On the possible involvement of bovine serum albumin precursor in ...

    Indian Academy of Sciences (India)

    2014-01-27

    Jan 27, 2014 ... mass finger printing analysis technique, herein we report the identification of a 70 kDa size protein (bovine serum albumin precursor, BSAP) .... Total cytoplasmic proteins from CHO cells were isolated using conventional cell ..... 2002 HIV-1 integration in the human genome favors active genes and local ...

  4. Laser microdissection of sensory organ precursor cells of Drosophila microchaetes.

    Directory of Open Access Journals (Sweden)

    Eulalie Buffin

    Full Text Available BACKGROUND: In Drosophila, each external sensory organ originates from the division of a unique precursor cell (the sensory organ precursor cell or SOP. Each SOP is specified from a cluster of equivalent cells, called a proneural cluster, all of them competent to become SOP. Although, it is well known how SOP cells are selected from proneural clusters, little is known about the downstream genes that are regulated during SOP fate specification. METHODOLOGY/PRINCIPAL FINDINGS: In order to better understand the mechanism involved in the specification of these precursor cells, we combined laser microdissection, toisolate SOP cells, with transcriptome analysis, to study their RNA profile. Using this procedure, we found that genes that exhibit a 2-fold or greater expression in SOPs versus epithelial cells were mainly associated with Gene Ontology (GO terms related with cell fate determination and sensory organ specification. Furthermore, we found that several genes such as pebbled/hindsight, scabrous, miranda, senseless, or cut, known to be expressed in SOP cells by independent procedures, are particularly detected in laser microdissected SOP cells rather than in epithelial cells. CONCLUSIONS/SIGNIFICANCE: These results confirm the feasibility and the specificity of our laser microdissection based procedure. We anticipate that this analysis will give new insight into the selection and specification of neural precursor cells.

  5. Sobre algunos precursores de la práctica farmacéutica en Cuba Cuba: On some precursors of pharmaceutical practice

    Directory of Open Access Journals (Sweden)

    José Antonio López Espinosa

    2009-12-01

    Full Text Available Se presentan las semblanzas de algunos de los primeros profesionales que ejercieron la ciencia farmacéutica en Cuba. Los datos que sirvieron de fuente para preparar esta obra de referencia se extrajeron en principio de varios documentos inéditos del período colonial y de otras publicaciones que vieron la luz con posterioridad. Dicha información se procesó de modo conveniente para sacar de las sombras los nombres de estos hombres que no deben ser desconocidos por las generaciones actuales y futuras de los que se consagran a esta profesión. El presente trabajo, que aspira a cumplir ese propósito, trata asimismo de constituirse en modesto tributo a su memoria.In present paper are showed the features of some of the first professional precursors of Pharmacy Science in Cuba. Previously, data as source to prepare this reference work were searched from some unpublished documents from colonial period and from other subsequent publications. Such information was processed in a suitable way to extract from the anonymity the name of these men that must no be unknown by present and future generations of that devoted to this profession. Present paper wants to fulfill this objective and to be a modest tribute to their memory.

  6. Whole-cell fungal transformation of precursors into dyes

    Directory of Open Access Journals (Sweden)

    Jarosz-Wilkołazka Anna

    2010-07-01

    Full Text Available Abstract Background Chemical methods of producing dyes involve extreme temperatures and unsafe toxic compounds. Application of oxidizing enzymes obtained from fungal species, for example laccase, is an alternative to chemical synthesis of dyes. Laccase can be replaced by fungal biomass acting as a whole-cell biocatalyst with properties comparable to the isolated form of the enzyme. The application of the whole-cell system simplifies the transformation process and reduces the time required for its completion. In the present work, four fungal strains with a well-known ability to produce laccase were tested for oxidation of 17 phenolic and non-phenolic precursors into stable and non-toxic dyes. Results An agar-plate screening test of the organic precursors was carried out using four fungal strains: Trametes versicolor, Fomes fomentarius, Abortiporus biennis, and Cerrena unicolor. Out of 17 precursors, nine were transformed into coloured substances in the presence of actively growing fungal mycelium. The immobilized fungal biomass catalyzed the transformation of 1 mM benzene and naphthalene derivatives in liquid cultures yielding stable and non-toxic products with good dyeing properties. The type of fungal strain had a large influence on the absorbance of the coloured products obtained after 48-hour transformation of the selected precursors, and the most effective was Fomes fomentarius (FF25. Whole-cell transformation of AHBS (3-amino-4-hydroxybenzenesulfonic acid into a phenoxazinone dye was carried out in four different systems: in aqueous media comprising low amounts of carbon and nitrogen source, in buffer, and in distilled water. Conclusions This study demonstrated the ability of four fungal strains belonging to the ecological type of white rot fungi to transform precursors into dyes. This paper highlights the potential of fungal biomass for replacing isolated enzymes as a cheaper industrial-grade biocatalyst for the synthesis of dyes and other

  7. Escenarios del arte bizantino

    National Research Council Canada - National Science Library

    Pablo C Díaz

    2017-01-01

    ... clásico greco-romano, y la recuperación del mundo bizantino, además del retraso de casi un siglo, viene marcada por la diferencia entre la luminosidad del primer renacimiento meridional y las brumas del humanismo casi barroco del luterano...

  8. Activación de la neurogénesis por el CSF-E en precursores neurales de ratón adulto

    OpenAIRE

    Madrigal Fernández, Miguel Ángel

    2012-01-01

    La activación de la neurogénesis a partir de células progenitoras del cerebro de mamíferos adultos abre una expectativa terapéutica en el campo de la neuroregeneración que requiere un control del proceso de neurogénesis y maduración funcional a partir de los Precursores Neurales. La evolución ontogénica de la composición y propiedades del “Nicho Neurogénico” conduce a una neurogénesis muy limitada en el adulto, que puede ser debida a una carencia de estímulos neurogénicos. El CSF es un factor...

  9. Production of activated carbon from a new precursor: Molasses

    Science.gov (United States)

    Legrouri, K.; Ezzine, M.; Ichcho, S.; Hannache, H.; Denoyel, R.; Pailler, R.; Naslain, R.

    2005-03-01

    Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulfuric acid, followed by carbonization. The adsorption capacity, the BET surface area, and the pore volume of the activated carbon were determined. The micropore volume was assessed by Dubinin- Radushkevich (DR) equation. The activated materials are mainly microporous and show the type I isotherm of the Brunauer classification for nitrogen adsorption. The activation in steam yielded a carbon that contains both micropores and supermicropores. Analysis of the nitrogen isotherm by BET and DR methods established that most of obtained carbons are highly microporous, with high surface areas (≥ 1200 m2/g) and very low mesoporosity.

  10. Ceramic fibers from Si-B-C polymer precursors

    Science.gov (United States)

    Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

    1993-01-01

    Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

  11. Structural basis for precursor protein-directed ribosomal peptide macrocyclization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kunhua; Condurso, Heather L.; Li, Gengnan; Ding, Yousong; Bruner, Steven D. (Florida)

    2016-11-11

    Macrocyclization is a common feature of natural product biosynthetic pathways including the diverse family of ribosomal peptides. Microviridins are architecturally complex cyanobacterial ribosomal peptides that target proteases with potent reversible inhibition. The product structure is constructed via three macrocyclizations catalyzed sequentially by two members of the ATP-grasp family, a unique strategy for ribosomal peptide macrocyclization. Here we describe in detail the structural basis for the enzyme-catalyzed macrocyclizations in the microviridin J pathway of Microcystis aeruginosa. The macrocyclases MdnC and MdnB interact with a conserved α-helix of the precursor peptide using a novel precursor-peptide recognition mechanism. The results provide insight into the unique protein–protein interactions that are key to the chemistry, suggest an origin for the natural combinatorial synthesis of microviridin peptides, and provide a framework for future engineering efforts to generate designed compounds.

  12. PREPARATION OF TANTALUM CARBIDE FROM AN ORGANOMETALLIC PRECURSOR

    Directory of Open Access Journals (Sweden)

    SOUZA C. P.

    1999-01-01

    Full Text Available In this work we have synthesized an organometallic oxalic precursor from tantalum oxide. This oxide was solubilized by heating with potassium hydrogen sulfate. In order to precipitate Ta2O5.nH2O, the fused mass obtained was dissolved in a sulfuric acid solution and neutralized with ammonia. The hydrated tantalum oxide precipitated was dissolved in an equimolar solution of oxalic acid/ammonium oxalate. The synthesis and the characterization of the tantalum oxalic precursor are described. Pyrolysis of the complex in a mixture of hydrogen and methane at atmospheric pressure was studied. The gas-solid reaction made it possible to obtain tantalum carbide, TaC, in the powder form at 1000oC. The natural sintering of TaC powder in an inert atmosphere at 1400°C during 10 hours, under inert atmosphere made it possible to densify the carbide to 96% of the theoretical value.

  13. Metacognitive Precursors: An Analysis in Children with Different Disabilities

    Directory of Open Access Journals (Sweden)

    María Consuelo Sáiz Manzanares

    2017-10-01

    Full Text Available The analysis of Metacognitive skills is a key element to guide the learning process. Current research has shown the initiation of these skills from an early age. The present study had two aims: (1 to validate a Scale Measuring Precursor Metacognitive Skills (SMPMS in children with diverse disabilities, and (2 to study possible significant different between different disabilities in precursor metacognitive skill use. We worked with 87 children with different disabilities, with an average age range of 24–37 months. The results have shown high indicators of reliability and validity of the SMPMS. We isolated two factors related to cognitive and metacognitive and self-regulation skills response to an adult. We also found significant differences in the acquisition of metacognitive and self-regulation skills among children with global developmental retardation as compared to children with expressive language and comprehension disability.

  14. Polyimide/polyamideimide composites from different polyimide precursors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.B. [Chonnam National University, Kwangju (Korea); Choi, Y.H. [Kumho Industry Ltd., Kwangju (Korea); Yim, B.T.; Park, J.S. [Kumho Petroleum Chemical Co., Taejeon (Korea)

    2001-03-01

    The various compositions of polyimide (PI)/polyamideimide (PAI) composites were prepared by heat treatment of the solvent cast PI precursors/PAI blends. The optical micrographs showed that a good compatibility was observed between poly(amic acid) (PAA) and PAI, but in the case of PAME/PAI mixtures, a phase separation apparently occurred due to the absence of ionic and/ or H{sub b}onding forces. Regardless of PI precursors, the similar tensile properties were observed. The tensile modulus of the composites were higher than that of the neat polyimide. The X-ray diffraction patterns of the composites showed that the chain rearrangement of PI was increased due to the plasticizing effect of PAI, which has lower glass transition temperature than that of PI, during thermal imidization process. (author)., 14 refs., 1 tab., 8 figs.

  15. Antarctic new particle formation from continental biogenic precursors

    Directory of Open Access Journals (Sweden)

    E.-M. Kyrö

    2013-04-01

    Full Text Available Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN. The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

  16. Creep and slip: Seismic precursors to the Nuugaatsiaq landslide (Greenland)

    Science.gov (United States)

    Poli, Piero

    2017-09-01

    Precursory signals to material's failure are predicted by numerical models and observed in laboratory experiments or using field data. These precursory signals are a marker of slip acceleration on weak regions, such as crustal faults. Observation of these precursory signals of catastrophic natural events, such as earthquakes and landslides, is necessary for improving our knowledge about the physics of the nucleation process. Furthermore, observing such precursory signals may help to forecast these catastrophic events or reduce their hazard. I report here the observation of seismic precursors to the Nuugaatsiaq landslide in Greenland. Time evolution of the detected precursors implies that an aseismic slip event is taking place for hours before the landslide, with an exponential increase of slip velocity. Furthermore, time evolution of the precursory signals' amplitude sheds light on the evolution of the fault physics during the nucleation process.

  17. J. B. Watson y la Publicidad, los Inicios de la Psicología del Consumidor

    Directory of Open Access Journals (Sweden)

    FELIPE PARRADO CORREDOR

    2013-01-01

    Full Text Available La investigación del comportamiento de las personas frente a los productos y servicios se remonta a los inicios del siglo XX y J. B. Watson es uno de sus principales precursores. Watson ofreció un curso de psicología aplicada titulado Psicología de la Publicidad, introdujo en varias empresas las técnicas experimentales para el mercadeo de sus productos y, tras su retiro de la vida académica, se vinculó a la agencia de publicidad Walter Thompson, donde desarrolló campañas masivas con los mismos principios de las reacciones emocionales condicionadas. En este ensayo se expone la importancia del trabajo de Watson en la psicología de la publicidad, como precursor de los desarrollos científicos de la psicología del consumidor.

  18. Review of Dolomite as Precursor of Geopolymer Materials

    OpenAIRE

    Azimi E.A.; Abdullah M.M.A.B.; Ming L.Y.; Yong H.C.; Hussin K.; Aziz I.H.

    2016-01-01

    Geopolymer is an environmentally friendly cementitious binder that does not require the existence of ordinary Portland cement (OPC). Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Previous commonly used materials include fly ash, clay and slag. The used of dolomite as precursor material in geopolymer field is still new and at the early stage of study. Only a few researchers have done studies on dolo...

  19. Effect of precursors on flavonoid production by Hydrocotyle ...

    African Journals Online (AJOL)

    Callus tissue of Hydrocotyle bonariensis was initiated from the leaf of H. bonariensis treated with 2 mg/l of 2,4-dichlorophenoxyacetic acid (2,4-D) and 1 mg/l kinetin. The culture was kept at 25°C, under light (cool white fluorescent tubes, 1200 lux). To optimize the precursors to increase the production of flavonoid, different ...

  20. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  1. Hemopoietic cell precursor responses to erythropoietin in plasma clot cultures

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, W.L.

    1979-01-01

    The time dependence of the response of mouse bone marrow cells to erythropoietin (Ep) in vitro was studied. Experiments include studies on the Ep response of marrow cells from normal, plethoric, or bled mice. Results with normal marrow reveal: (1) Not all erythroid precursors (CFU-E) are alike in their response to Ep. A significant number of the precursors develop to a mature erythroid colony after very short Ep exposures, but they account for only approx. 13% of the total colonies generated when Ep is active for 48 hrs. If Ep is active more than 6 hrs, a second population of erythroid colonies emerges at a nearly constant rate until the end of the culture. Full erythroid colony production requires prolonged exposure to erythropoietin. (2) The longer erythropoietin is actively present, the larger the number of erythroid colonies that reach 17 cells or more. Two distinct populations of immediate erythroid precursors are also present in marrow from plethoric mice. In these mice, total colony numbers are equal to or below those obtained from normal mice. However, the population of fast-responding CFU-E is consistently decreased to 10 to 20% of that found in normal marrow. The remaining colonies are formed from plethoric marrow at a rate equal to normal marrow. With increasing Ep exposures, the number of large colonies produced increases. From the marrow of bled mice, total erythroid colony production is equal to or above that of normal marrow. Two populations of colony-forming cells are again evident, with the fast-responding CFU-E being below normal levels. The lack of colonies from this group was compensated in bled mice by rapid colony production in the second population. A real increase in numbers of precursors present in this pool increased the rate of colony production in culture to twice that of normal marrow. The number of large colonies obtained from bled mice was again increased as the Ep exposure was lengthened. (ERB)

  2. Hydroxycinnamic acid ethyl esters as precursors to ethylphenols in wine.

    Science.gov (United States)

    Hixson, Josh L; Sleep, Nicola R; Capone, Dimitra L; Elsey, Gordon M; Curtin, Christopher D; Sefton, Mark A; Taylor, Dennis K

    2012-03-07

    A method for determining ethyl coumarate and ethyl ferulate in wine using GC-MS with deuterium-labeled analogues has been developed and used to measure the evolution of these two esters during the production of two commercial monovarietal red wines, cv. Grenache and Shiraz. During fermentation, the concentration of ethyl coumarate rose from low levels to 0.4 mg/L in Grenache and 1.6 mg/L in Shiraz wines. These concentrations then increased further during barrel aging to 1.4 and 3.6 mg/L, respectively. The concentration of ethyl ferulate was much lower, reaching a maximum of only 0.09 mg/L. Conversion of ethyl coumarate and ethyl ferulate to their corresponding ethylphenols was observed during fermentations of a synthetic medium with two strains of Dekkera bruxellensis (AWRI 1499 and AWRI 1608), while a third (strain AWRI 1613) produced no ethylphenols at all from these precursors. Strains AWRI 1499 and 1608 produced 4-ethylphenol from ethyl coumarate in 68% and 57% yields, respectively. The corresponding yields of 4-ethylguaiacol from ethyl ferulate were much lower, 7% and 3%. Monitoring of ethyl coumarate and ethyl ferulate concentration during the Dekkera fermentations showed that the selectivity for ethylphenol production according to yeast strain and the precursor was principally a result of variation in esterase activity. Consequently, ethyl coumarate can be considered to be a significant precursor to 4-ethylphenol in wines affected by these two strains of Brettanomyces/Dekkera yeast, while ethyl ferulate is not an important precursor to 4-ethylguaiacol.

  3. Spectroscopy Study of Synthetic Forsterite Obtained from Zeolite Precursors

    OpenAIRE

    Kosanović, Cleo; Stubičar, Nada; Tomašić, N.; Stubičar, M.; Subotić, Boris; Gajović, Andreja; Sekovanić, L.

    2008-01-01

    Important ceramics materials are prepared from aluminosilicate based precursors using novel methods, offering at the same time a better control over many important properties. Forsterite, due to its good refractoriness with melting point at 2163 K, excellent electrical insulation properties even at high temperatures, low dielectric permittivity, thermal expansion and chemical stability, is a material of interest to engineers and designers especially as an active medium for tuneable laser and ...

  4. Acrylonitrile, an advantageous precursor to synthesize nitrogen doped carbon nanotubes

    Science.gov (United States)

    Aguilar-Elguézabal, A.; Román-Aguirre, M.; De la Torre, L.; Zaragoza, E. A.

    2017-05-01

    The nitrogen doped carbon nanotubes present specific characteristics that offer better performance than pure carbon nanotubes for application like biomedicine, hydrogen adsorption and electrocataytic devices. This work present a simple method to obtain well-aligned nitrogen doped multi wall carbon nanotubes, which present open channels with diameter around 50 nm. These carbon nanotubes are obtained using acrylonitrile as carbon and nitrogen source, which offers some advantages on the use of other precursors like ammonia, pyridine, benzylamine, acetonitrile or melamine.

  5. Current Development in Isoprenoid Precursor Biosynthesis and Regulation

    OpenAIRE

    Chang, Wei-chen; Song, Heng; Liu, Hung-wen; Liu, Pinghua

    2013-01-01

    Isoprenoids are one of the largest classes of natural products and all of them are constructed from two precursors, isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP). For decades, the mevalonic acid (MVA) pathway was proposed to be the only IPP and DMAPP biosynthetic pathway. This review summarizes the newly discovered IPP and DMAPP production pathways since late 1990s, their distribution among different kingdoms, and their roles in secondary metabolite production...

  6. Development of techniques for tagging precursor and essential chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  7. LWIR hyperspectral imaging application and detection of chemical precursors

    Science.gov (United States)

    Lavoie, Hugo; Thériault, Jean-Marc; Bouffard, François; Puckrin, Eldon; Dubé, Denis

    2012-10-01

    Detection and identification of Toxic industrial chemicals (TICs) represent a major challenge to protect and sustain first responder and public security. In this context, passive Hyperspectral Imaging (HSI) is a promising technology for the standoff detection and identification of chemical vapors emanating from a distant location. To investigate this method, the Department of National Defense and Public Safety Canada have mandated Defense Research and Development Canada (DRDC) - Valcartier to develop and test Very Long Wave Infrared (VLWIR) HSI sensors for standoff detection. The initial effort was focused to address the standoff detection and identification of toxic industrial chemicals (TICs), surrogates and precursors. Sensors such as the Improved Compact ATmospheric Sounding Interferometer (iCATSI) and the Multi-option Differential Detection and Imaging Fourier Spectrometer (MoDDIFS) were developed for this application. This paper presents the sensor developments and preliminary results of standoff detection and identification of TICs and precursors. The iCATSI and MoDDIFS sensors are based on the optical differential Fourier-transform infrared (FTIR) radiometric technology and are able to detect, spectrally resolve and identify small leak at ranges in excess of 1 km. Results from a series of trials in asymmetric threat type scenarios are reported. These results serve to establish the potential of passive standoff HSI detection of TICs, precursors and surrogates.

  8. Spectroscopy Study of Synthetic Forsterite Obtained from Zeolite Precursors

    Directory of Open Access Journals (Sweden)

    Subotić, B.

    2008-02-01

    Full Text Available Important ceramics materials are prepared from aluminosilicate based precursors using novel methods, offering at the same time a better control over many important properties. Forsterite, due to its good refractoriness with melting point at 2163 K, excellent electrical insulation properties even at high temperatures, low dielectric permittivity, thermal expansion and chemical stability, is a material of interest to engineers and designers especially as an active medium for tuneable laser and is also a material of interest to SOFC (Solid oxide fuel cells manufacturers. The aim of this study is to investigate the synthesis of crystalline forsterite using different zeolite precursors previously activated by ball milling. Synthetic forsterite was synthesized from different zeolite precursors and MgO combining highenergy ball milling and thermal treatment of the mixture under determined conditions of time and temperature for each operation. In this research are studied the solid-state phase transformations taking place at temperatures below 1273 K. The obtained products were characterized using different spectroscopy techniques in comparison with surface analysis method and X-ray diffraction.

  9. Il dono del racconto

    DEFF Research Database (Denmark)

    Polito, Paola

    1998-01-01

    L'articolo indaga a vari livelli strutturali del romanzo "Il coraggio del pettirosso" (rete metaforica, dialogismo diegetico, dialogismo come fenomeno di voce, strategie discorsive messe in atto dalla voce narrante, stile colloquiale) la complessa realizzazione testuale del genere narrativo...

  10. Precursor Analysis for Flight- and Ground-Based Anomaly Risk Significance Determination

    Science.gov (United States)

    Groen, Frank

    2010-01-01

    This slide presentation reviews the precursor analysis for flight and ground based anomaly risk significance. It includes information on accident precursor analysis, real models vs. models, and probabilistic analysis.

  11. Liquid precursor for deposition of indium selenide and method of preparing the same

    Science.gov (United States)

    Curtis, Calvin J.; Miedaner, Alexander; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S.; Hersh, Peter A.; Eldada, Louay; Stanbery, Billy J.

    2015-09-22

    Liquid precursors containing indium and selenium suitable for deposition on a substrate to form thin films suitable for semiconductor applications are disclosed. Methods of preparing such liquid precursors and method of depositing a liquid precursor on a substrate are also disclosed.

  12. Pig epidermal growth factor precursor contains segments that are highly conserved among species

    DEFF Research Database (Denmark)

    Jørgensen, P E; Jensen, L.G.; Sørensen, B S

    1998-01-01

    The 53-aa polypeptide epidermal growth factor (EGF) is synthesized as a 1200-aa precursor. The non-EGF part of the precursor is very long compared with EGF, and can therefore be expected to have a biological role of its own. We have sequenced cDNA of the pig EGF precursor and compared a 668-aa...

  13. del cambio

    Directory of Open Access Journals (Sweden)

    Alejandro Canales

    2006-01-01

    Full Text Available El artículo analiza las propuestas y los compromisos en materia de cobertura y de financiamiento en el periodo 2000-2006. En particular, revisa las modificaciones y los ajustes de los tres principales documentos en los que se expresaron las iniciativas: el de la Asociación Nacional de Universidades e Instituciones de Educación Superior, el del equipo de la transición y el programa sectorial. Los resultados muestran que las cifras de atención a la demanda educativa e inversión quedaron lejos de las metas autoimpuestas por el gobierno federal y que será necesario realizar mayores esfuerzos para atender tales desafíos.

  14. Molecular analysis of precursor lesions in familial pancreatic cancer.

    Directory of Open Access Journals (Sweden)

    Tatjana Crnogorac-Jurcevic

    Full Text Available With less than a 5% survival rate pancreatic adenocarcinoma (PDAC is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical.We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses.Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic

  15. Radiative precursors driven by converging blast waves in noble gases

    Energy Technology Data Exchange (ETDEWEB)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s{sup −1} blast waves through gases of densities of the order 10{sup −5} g cm{sup −3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  16. del, Einstein, Mach, Gamow, and Lanczos: Gödel's remarkable excursion into cosmology

    Science.gov (United States)

    Rindler, Wolfgang

    2009-06-01

    This article is an expanded version of a talk given at the International Symposium Celebrating the 100th Birthday of Kurt Gödel (Vienna, 2006). It seeks to trace the path which led this preeminent mathematical logician to discover one of the famous results of General Relativity, the rotating Gödel Universe. This universe has some remarkable properties, which gave the philosophers plenty to worry about. It allows a person to travel into his own past, with all the ensuing causal paradoxes; it allows no unique temporal ordering of events; and though Gödel's Universe is rigid and infinite, the Foucault pendulum planes everywhere in it rotate in unison, a clear affront to adherents of Mach's Principle. We also discuss some lesser known precursors in the field, who just missed discovering Gödel's universe. While the article gives all the necessary derivations in simplified form (for example, of the metric and its geodesics), much of it should be accessible to the general reader, who can simply skip most of the mathematics. [Reprinted, with permission, from Kurt Gödel and the Foundations of Mathematics: Horizons of Truth, edited by Matthias Baaz, Christos H. Papadimitriou, Dana S. Scott, Hilary Putnam, and Charles L. Harper, Jr. (Cambridge U. P., New York, 2009).

  17. Patterned Fluorescence Images with Indigo Precursors in Polymer Film

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Bora; Oh, Eun Hae; Lee, Chan Woo; Kim, Jongman [Hanyang Univ., Seoul (Korea, Republic of)

    2013-04-15

    We have developed a new strategy for the generation of patterned fluorescence images in polymer film. A fluorescent acetyl protected indole 6 was transformed to a nonfluorescent indigo dye 7 by UV irradiation. In addition, a t-Boc protected fluorescent indigo molecule 8 was also converted to a nonfluorescent indigo derivative 7 under a chemical amplification condition. Photomasked UV irradiation of the precursor molecules allowed efficient generation of patterned fluorescence images in polymer film. The strategy described in current investigation is believed to be an important addition to the fluorescent patterning technology.

  18. Gelcasting polymeric precursors for producing net-shaped graphites

    Science.gov (United States)

    Klett, James W.; Janney, Mark A.

    2005-02-15

    The present invention discloses a method for molding complex and intricately shaped high density monolithic carbon, carbon-carbon, graphite, and thermoplastic composites using gelcasting technology. The method comprising a polymeric carbon precursor, a solvent, a dispersant, an anti-foaming agent, a monomer system, and an initiator system. The components are combined to form a suspension which is poured into a mold and heat-treated to form a thermoplastic part. The thermoplastic part can then be further densified and heat-treated to produce a high density carbon or graphite composite. The present invention also discloses the products derived from this method.

  19. Hydrogeochemical precursors of strong earthquakes in Kamchatka: further analysis

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2001-01-01

    Full Text Available For many years, ion and gas content data have been collected from the groundwater of three deep wells in the southern area of the Kamchatka peninsula, Russia. In the last ten years, five earthquakes with M > 6.5 have occurred within 250 km of the wells. In a previous study, we investigated the possibility that the hydrogeochemical time series contained precursors. The technique used was to assume that each signal with an amplitude of three times the standard deviation is an irregularity and we then defined anomalies as irregularities occurring simultaneously in the data for more than one parameter at each well. Using this method, we identified 11 anomalies with 8 of them being possible successes and 3 being failures as earthquake precursors. Precursors were obtained for all five earthquakes that we considered. In this paper, we allow for the cross-correlation found between the gas data sets and in some cases, between the ion data sets. No cross-correlation has been found between gas and ion content data. Any correlation undermines the idea that an anomaly might be identified from irregularities appearing simultaneously on different parameters at each site. To refine the technique, we re-examine the hydrogeochemical data and define as anomalies those irregularities occurring simultaneously only in the data of two or more uncorrelated parameters. We then restricted the analysis to the cases of just the gas content data and the ion content data. In the first case, we found 6 successes and 2 failures, and in the second case, we found only 3 successes. In the first case, the precursors appear only for three of the five earthquakes we considered, and in the second case, only for two, but these are the earthquakes nearest to the wells. Interestingly, it shows that when a strict set of rules for defining an anomaly is used, the method produces only successes and when less restrictive rules are used, earthquakes further from the well are implicated, but

  20. Anomalous astronomical time-latitude residuals: a potential earthquake precursor

    Science.gov (United States)

    Hu, Hui; Su, You-Jin; Gao, Yi-Fei; Wang, Rui

    2016-09-01

    The geophysical mechanism behind astronomical time-latitude residuals (ATLR) are discussed. The photoelectric astrolabe at Yunnan Observatory (YO) observed apparent synchronous anomalous ATLR before the Wenchuan M8.0 earthquake (EQ) in May 12, 2008 and the Lushan M7.0 EQ n April 20, 2013. We compared the ATLR from the YO photoelectric astrolabe and EQ data since 1976. Anomalous ATLR was observed before several strong EQs in the Yunnan Province. We believe the photoelectric astrolabe can be used to predict strong EQs and the anomalous ATLR are a potential EQ precursor.

  1. Multifunctional Silica Nanoparticles Modified via Silylated-Decaborate Precursors

    Directory of Open Access Journals (Sweden)

    Fatima Abi-Ghaida

    2015-01-01

    Full Text Available A new class of multifunctional silica nanoparticles carrying boron clusters (10-vertex closo-decaborate and incorporating luminescent centers (fluorescein has been developed as potential probes/carriers for potential application in boron neutron capture therapy (BNCT. These silica nanoparticles were charged in situ with silylated-fluorescein fluorophores via the Stöber method and their surface was further functionalized with decaborate-triethoxysilane precursors. The resulting decaborate dye-doped silica nanoparticles were characterized by TEM, solid state NMR, DLS, nitrogen sorption, elemental analysis, and fluorescence spectroscopy.

  2. Endophytic fungi as a source of biofuel precursors.

    Science.gov (United States)

    Santos-Fo, Florisvaldo; Fill, Taicia Pacheco; Nakamura, Joanita; Monteiro, Marcos Roberto; Rodrigues-Fo, Edson

    2011-07-01

    Endophytic fungi, isolated from a number of different species of tropical plants, were investigated for lipid biodiesel precursor production. The extracts produced from liquid cultures of these fungi were subjected to acidcatalyzed transesterification reactions with methanol producing methyl esters and then analyzed through chromatographic (GC-FID) and spectrometric techniques (MS, NMR ¹H). The European Standard Method, EN 14103, was used for the quantification of methyl esters extracted from the fungi of the species and genera studied. Xylariaceous fungi exhibited the highest concentrations of methyl esters (91%), and hence may be a promising source for biofuel.

  3. Insect pheromones and precursors in female African elephant urine.

    Science.gov (United States)

    Goodwin, Thomas E; Eggert, Mindy S; House, Sam J; Weddell, Margaret E; Schulte, Bruce A; Rasmussen, L E L

    2006-08-01

    Using automated solid-phase dynamic extraction and gas chromatography-mass spectrometry, our search for urinary chemical signals from ovulatory female African elephants (Loxodonta africana) has revealed the bark beetle aggregation pheromones frontalin, exo-brevicomin, and endo-brevicomin, as well as their precursors and the aphid alarm pheromones (E,E)-alpha-farnesene and (E)-beta-farnesene. Enantiomeric ratios for brevicomins have been determined. Prior discovery of common insect/elephant pheromones in Asian elephants, namely, (Z)-7-dodecenyl acetate and frontalin, suggests that the present findings may yield valuable insights into chemical communication among African elephants.

  4. Ionospheric parameters as the precursors of disturbed geomagnetic conditions

    Science.gov (United States)

    Blagoveshchensky, D. V.; Sergeeva, M. A.; Kozlovsky, A.

    2017-12-01

    Geomagnetic storms and substorms are the principal elements of the disturbed Space Weather conditions. The aim of the study was to reveal the ionospheric precursors that can be used to forecast geomagnetic disturbance beginning. To study the ionospheric processes before, during and after magnetic storms and substorms data from Sodankylä Geophysical Observatory was used (geomagnetic coordinates: 64.1oN, 119.2oE). In earlier works the Main Effect (ME) was revealed for substorms. It consists of the following steps: (a) the increase of critical frequency foF2 from its quiet median before and during the substorm growth phase, four-five hours before To moment that is the moment of the expansion phase onset, (b) the foF2 decrease to the level lower than its median just after To and until Te that is the moment of the end of the expansion phase, (c) the issue ;a; repeated during the recovery phase (d) two bell-shape spikes in the cutoff frequency values foEs: first spike occurs three hours before To, second spike - during the expansion phase within the interval between To and Te. In the present work it is shown that ME manifestations can be used as precursors of magnetic substorms at high-latitudes (geomagnetic latitudes 50oN-65oN). In particular, the foF2 growth some hours before To can be used as a precursor of substorm development. The first foEs bell-shaped spike also can be used for short-term forecasting, two-three hours in advance of a substorm. Furthermore, the storms between 2008 and 2012 were studied. It was revealed that the similar ME also takes place in the case of magnetic storms but within the different time scale. More specifically, the first ME maximum in foF2 values occurs one-two days before the storm beginning and can be used as its precursor. In addition, the foEs spike takes place approximately ten hours before a storm and also can be used for the prediction of the storm beginning.

  5. Polymer precursors for SiC ceramic materials

    Science.gov (United States)

    Litt, Morton H.

    1986-01-01

    Work on precursor polymers to SiC was performed, concentrating on polymers made from decamethyl cyclohexasilyene units. The initial approach was to synthesize mixed diphenyl decamethyl cyclohexasilane, dephenylate, and polymerize. This produced polymers which had yields of up to 50 percent SiC. (Theoretical yield is 75 percent). The present approach is to make the polymer through the intermediate trans-1,4-diphenyl decamethyl cyclohexasilane. This should produce a crystalline polymer and high strength fibers. These will be thermally decomposed to SiC fibers. This requires new chemistry which is currently being studied.

  6. Ion Propulsion - An Enabling Technology for Interstellar Precursor Missions

    Science.gov (United States)

    Fearn, D. G.

    In this paper it is shown that an advanced form of gridded ion thruster, employing a 4-grid ion extraction and acceleration system, can provide a velocity increment and specific impulse of interest to interstellar precursor missions, extending to a few hundred astronomical units from the sun. In this it is assumed that a nuclear power source is available with a mass-to-power ratio of 15 to 35 kg/kW and an output of several tens of kW. Mission durations are of about 25 years and the velocity increment provided exceeds 37 km/s.

  7. Superhydrophobic Ceramic Coatings by Solution Precursor Plasma Spray

    Science.gov (United States)

    Cai, Yuxuan; Coyle, Thomas W.; Azimi, Gisele; Mostaghimi, Javad

    2016-04-01

    This work presents a novel coating technique to manufacture ceramic superhydrophobic coatings rapidly and economically. A rare earth oxide (REO) was selected as the coating material due to its hydrophobic nature, chemical inertness, high temperature stability, and good mechanical properties, and deposited on stainless steel substrates by solution precursor plasma spray (SPPS). The effects of various spraying conditions including standoff distance, torch power, number of torch passes, types of solvent and plasma velocity were investigated. The as-sprayed coating demonstrated a hierarchically structured surface topography, which closely resembles superhydrophobic surfaces found in nature. The water contact angle on the SPPS superhydrophobic coating was up to 65% higher than on smooth REO surfaces.

  8. Precursors for liver gluconeogenesis in periparturient dairy cows

    DEFF Research Database (Denmark)

    Larsen, Mogens; Kristensen, Niels Bastian

    2013-01-01

    The review is based on a compiled data set from studies quantifying liver release of glucose concomitant with uptake of amino acids (AA) and other glucogenic precursors in periparturient dairy cows. It has become dogma that AAs are significant contributors to liver gluconeogenesis in early....... The quantitative data on liver metabolism of AA do not support the hypothesis that the rapid post partum increase in net liver release of glucose is supported by increased utilisation of AA for gluconeogenesis. Only alanine is likely to contribute to liver release of glucose through its role in the inter...

  9. Persistence of perfluoroalkyl acid precursors in AFFF-impacted groundwater and soil.

    Science.gov (United States)

    Houtz, Erika F; Higgins, Christopher P; Field, Jennifer A; Sedlak, David L

    2013-08-06

    Several classes of polyfluorinated chemicals that are potential precursors to the perfluorinated carboxylates and sulfonates are present in aqueous film-forming foams (AFFF). To assess the persistence of these AFFF-derived precursors, groundwater, soil, and aquifer solids were obtained in 2011 from an unlined firefighter training area at a U.S. Air Force Base where AFFF was regularly used between 1970 and 1990. To measure the total concentration of perfluorinated carboxylate and sulfonate precursors in archived AFFF formulations and AFFF-impacted environmental samples, a previously developed assay that uses hydroxyl radical to oxidize precursors to perfluorinated carboxylates was adapted for these media. This assay was employed along with direct measurement of 22 precursors found in AFFF and a suite of other poly- and perfluoroalkyl substances (PFASs). On a molar basis, precursors accounted for 41-100% of the total concentration of PFASs in archived AFFF formulations. In the training area, precursors measured by the oxidation assay accounted for an average of 23% and 28% of total PFASs (i.e., precursors and perfluorinated carboxylates and sulfonates) in groundwater and solids samples, respectively. One precursor in AFFF, perfluorohexane sulfonamide amine, was observed on several highly contaminated soil and aquifer solids samples, but no other precursors present in AFFF formulations were detected in any samples at this field site. Suspected intermediate transformation products of precursors in AFFF that were directly measured accounted for approximately half of the total precursor concentration in samples from the training site. The fraction of PFASs consisting of perfluorinated carboxylates and sulfonates was greater in groundwater and solid samples than in any archived AFFF formulations, suggesting that much of the mass of precursors released at the site was converted to perfluorinated carboxylates and sulfonates. The precursors that have persisted at this site

  10. Perfluoroalkyl Acids (PFAAs) and Selected Precursors in the Baltic Sea Environment: Do Precursors Play a Role in Food Web Accumulation of PFAAs?

    Science.gov (United States)

    Gebbink, Wouter A; Bignert, Anders; Berger, Urs

    2016-06-21

    The present study examined the presence of perfluoroalkyl acids (PFAAs) and selected precursors in the Baltic Sea abiotic environment and guillemot food web, and investigated the relative importance of precursors in food web accumulation of PFAAs. Sediment, water, zooplankton, herring, sprat, and guillemot eggs were analyzed for perfluoroalkane sulfonic acids (PFSAs; C4,6,8,10) and perfluoroalkyl carboxylic acids (PFCAs; C6-15) along with six perfluoro-octane sulfonic acid (PFOS) precursors and 11 polyfluoroalkyl phosphoric acid diesters (diPAPs). FOSA, FOSAA and its methyl and ethyl derivatives (Me- and EtFOSAA), and 6:2/6:2 diPAP were detected in sediment and water. While FOSA and the three FOSAAs were detected in all biota, a total of nine diPAPs were only detected in zooplankton. Concentrations of PFOS precursors and diPAPs exceeded PFOS and PFCA concentrations, respectively, in zooplankton, but not in fish and guillemot eggs. Although PFOS precursors were present at all trophic levels, they appear to play a minor role in food web accumulation of PFOS based on PFOS precursor/PFOS ratios and PFOS and FOSA isomer patterns. The PFCA pattern in fish could not be explained by the intake pattern based on PFCAs and analyzed precursors, that is, diPAPs. Exposure to additional precursors might therefore be a dominant exposure pathway compared to direct PFCA exposure for fish.

  11. Initiation of Convection in a Classical Nova Precursor

    Science.gov (United States)

    Dursi, L. J.; Calder, A. C.; Ricker, P. M.; Truran, J. W.; Zingale, M.; Fryxell, B.; Olson, K.; Rosner, R.; Timmes, F. X.; Tufo, H.; MacNeice, P.

    2001-12-01

    Classical Novae result from the explosive thermonuclear burning of material accreted from a companion star onto the surface of a white dwarf. Observed abundances and explosion energies estimated from observations indicate that there must be significant mixing of the heavier material of the white dwarf (C/O) into the lighter accreted material (H/He). Accordingly, nova models must incorporate a mechanism that will dredge up the heavier white dwarf material, and fluid motions from an early convection phase is one proposed mechanism. We present results from two-dimensional simulations of classical nova precursor models that demonstrate the beginning of a convective phase during the `simmering' of a Nova precursor. We use a new hydrostatic equilibrium hydrodynamics module recently developed for the adaptive-mesh code FLASH. The two-dimensional models are based on the one-dimensional models of Ami Glasner (Glasner et al. 1997), and were evolved with FLASH from a pre-convective state to the onset of convection. In addition, we present the details of the hydrostatic equilibrium module and the hydrostatic boundary conditions used in the simulations. This research has been supported by the U.S. Department of Energy under grant no. B341495 to the ASCI Flash Center at the University of Chicago.

  12. An Accident Precursor Analysis Process Tailored for NASA Space Systems

    Science.gov (United States)

    Groen, Frank; Stamatelatos, Michael; Dezfuli, Homayoon; Maggio, Gaspare

    2010-01-01

    Accident Precursor Analysis (APA) serves as the bridge between existing risk modeling activities, which are often based on historical or generic failure statistics, and system anomalies, which provide crucial information about the failure mechanisms that are actually operative in the system and which may differ in frequency or type from those in the various models. These discrepancies between the models (perceived risk) and the system (actual risk) provide the leading indication of an underappreciated risk. This paper presents an APA process developed specifically for NASA Earth-to-Orbit space systems. The purpose of the process is to identify and characterize potential sources of system risk as evidenced by anomalous events which, although not necessarily presenting an immediate safety impact, may indicate that an unknown or insufficiently understood risk-significant condition exists in the system. Such anomalous events are considered accident precursors because they signal the potential for severe consequences that may occur in the future, due to causes that are discernible from their occurrence today. Their early identification allows them to be integrated into the overall system risk model used to intbrm decisions relating to safety.

  13. The NAD(+) precursor nicotinamide riboside decreases exercise performance in rats.

    Science.gov (United States)

    Kourtzidis, Ioannis A; Stoupas, Andreas T; Gioris, Ioannis S; Veskoukis, Aristidis S; Margaritelis, Nikos V; Tsantarliotou, Maria; Taitzoglou, Ioannis; Vrabas, Ioannis S; Paschalis, Vassilis; Kyparos, Antonios; Nikolaidis, Michalis G

    2016-01-01

    Nicotinamide adenine dinucleotide (NAD(+)) and its phosphorylated form (NADP(+)) are key molecules in ubiquitous bioenergetic and cellular signaling pathways, regulating cellular metabolism and homeostasis. Thus, supplementation with NAD(+) and NADP(+) precursors emerged as a promising strategy to gain many and multifaceted health benefits. In this proof-of-concept study, we sought to investigate whether chronic nicotinamide riboside administration (an NAD(+) precursor) affects exercise performance. Eighteen Wistar rats were equally divided in two groups that received either saline vehicle or nicotinamide riboside at a dose of 300 mg/kg body weight/day for 21 days via gavage. At the end of the 21-day administration protocol, both groups performed an incremental swimming performance test. The nicotinamide riboside group showed a tendency towards worse physical performance by 35 % compared to the control group at the final 10 % load (94 ± 53 s for the nicotinamide riboside group and 145 ± 59 s for the control group; P = 0.071). Our results do not confirm the previously reported ergogenic effect of nicotinamide riboside. The potentially negative effect of nicotinamide riboside administration on physical performance may be attributed to the pleiotropic metabolic and redox properties of NAD(+) and NADP(+).

  14. Advanced accident sequence precursor analysis level 2 models

    Energy Technology Data Exchange (ETDEWEB)

    Galyean, W.J.; Brownson, D.A.; Rempe, J.L. [and others

    1996-03-01

    The U.S. Nuclear Regulatory Commission Accident Sequence Precursor program pursues the ultimate objective of performing risk significant evaluations on operational events (precursors) occurring in commercial nuclear power plants. To achieve this objective, the Office of Nuclear Regulatory Research is supporting the development of simple probabilistic risk assessment models for all commercial nuclear power plants (NPP) in the U.S. Presently, only simple Level 1 plant models have been developed which estimate core damage frequencies. In order to provide a true risk perspective, the consequences associated with postulated core damage accidents also need to be considered. With the objective of performing risk evaluations in an integrated and consistent manner, a linked event tree approach which propagates the front end results to back end was developed. This approach utilizes simple plant models that analyze the response of the NPP containment structure in the context of a core damage accident, estimate the magnitude and timing of a radioactive release to the environment, and calculate the consequences for a given release. Detailed models and results from previous studies, such as the NUREG-1150 study, are used to quantify these simple models. These simple models are then linked to the existing Level 1 models, and are evaluated using the SAPHIRE code. To demonstrate the approach, prototypic models have been developed for a boiling water reactor, Peach Bottom, and a pressurized water reactor, Zion.

  15. AMYPdb: A database dedicated to amyloid precursor proteins

    Directory of Open Access Journals (Sweden)

    Delamarche Christian

    2008-06-01

    Full Text Available Abstract Background Misfolding and aggregation of proteins into ordered fibrillar structures is associated with a number of severe pathologies, including Alzheimer's disease, prion diseases, and type II diabetes. The rapid accumulation of knowledge about the sequences and structures of these proteins allows using of in silico methods to investigate the molecular mechanisms of their abnormal conformational changes and assembly. However, such an approach requires the collection of accurate data, which are inconveniently dispersed among several generalist databases. Results We therefore created a free online knowledge database (AMYPdb dedicated to amyloid precursor proteins and we have performed large scale sequence analysis of the included data. Currently, AMYPdb integrates data on 31 families, including 1,705 proteins from nearly 600 organisms. It displays links to more than 2,300 bibliographic references and 1,200 3D-structures. A Wiki system is available to insert data into the database, providing a sharing and collaboration environment. We generated and analyzed 3,621 amino acid sequence patterns, reporting highly specific patterns for each amyloid family, along with patterns likely to be involved in protein misfolding and aggregation. Conclusion AMYPdb is a comprehensive online database aiming at the centralization of bioinformatic data regarding all amyloid proteins and their precursors. Our sequence pattern discovery and analysis approach unveiled protein regions of significant interest. AMYPdb is freely accessible 1.

  16. Silicone Resin Applications for Ceramic Precursors and Composites

    Directory of Open Access Journals (Sweden)

    Masaki Narisawa

    2010-06-01

    Full Text Available This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

  17. High-quality CdTe films from nanoparticle precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, D.L.; Pehnt, M.; Urgiles, E. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    In this paper the authors demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 {Angstrom} diameter) onto substrates at elevated temperatures (T = 280-440{degrees}C) with no further thermal treatment. These films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of {approx}0.1-0.3 {mu}m for film sprayed at 400{degrees}C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.

  18. Applications of Anomaly Detection and Precursor Identification in Airspace Operations

    Science.gov (United States)

    Matthews, Bryan L.

    2017-01-01

    As we continue to advance the U.S. National Airspace into the next generation of air traffic, we face challenges in both increase in complexity, as well as, a significant growth in traffic volume. Addressing these challenges, while maintaining the same level of safety is an important application of data mining. Because of these significant shifts in airspace design and usage there is a need to identify current and emergent safety risks along with their potential precursors. In recent years NASA has made advancements in developing scalable methods to address this effort in the Big Data paradigm. Multiple kernel anomaly detection approaches have been employed on both surveillance radar data and flight operational quality assurance data to identify operationally significant safety risks. Additionally, events have been explored with a recently developed precursor identification tool to discover states that reveal an increased probability of a safety event. These tools can be used to discover emerging safety risks that may not be currently monitored, which allows for mitigation tactics to be employed and ultimately make the overall airspace safer. This talk will discuss an overview of these methods and a discussion of the findings.

  19. Lunar precursor effects in the solar wind and terrestrial magnetosphere

    Science.gov (United States)

    Halekas, J. S.; Poppe, A. R.; Farrell, W. M.; Delory, G. T.; Angelopoulos, V.; McFadden, J. P.; Bonnell, J. W.; Glassmeier, K. H.; Plaschke, F.; Roux, A.; Ergun, R. E.

    2012-05-01

    The two ARTEMIS probes observe significant precursor activity upstream from the Moon, when magnetically connected to the dayside lunar surface. The most common signature consists of high levels of whistler wave activity near half of the electron cyclotron frequency. This precursor activity extends to distances of many thousands of km, in both the solar wind and terrestrial magnetosphere. In the magnetosphere, electrons reflect from a combination of magnetic and electrostatic fields above the lunar surface, forming loss cone distributions. In the solar wind they generally form conics, as a result of reflection from an obstacle moving with respect to the plasma frame (just as at a shock). The anisotropy associated with these reflected electrons provides the free energy source for the whistlers, with cyclotron resonance conditions met between the reflected source population and Moonward-propagating waves. These waves can in turn affect incoming plasma, and we observe significant perpendicular electron heating and plasma density depletions in some cases. In the magnetosphere, we also observe broadband electrostatic modes driven by beams of secondary electrons and/or photoelectrons accelerated outward from the surface. We also occasionally see waves near the ion cyclotron frequency in the magnetosphere. These lower frequency waves, which may result from the presence of ions of lunar origin, modulate the whistlers described above, as well as the electrons. Taken together, our observations suggest that the presence of the Moon leads to the formation of an upstream region analogous in many ways to the terrestrial electron foreshock.

  20. Novel drug delivery strategies for porphyrins and porphyrin precursors

    Science.gov (United States)

    Morrow, D. I. J.; Donnelly, R. F.

    2009-06-01

    superficial lesions, such as actinic keratosis. In addition, photodynamic antimicrobial chemotherapy (PACT) is attracting increasing interest for the treatment of infection. However, delivery strategies for topical PDT and PACT are still based on application of rather simplistic cream and solution formulations, with little consideration given to thermodynamics, targeting or the physicochemical properties of the active agent. Purpose-designed dosage forms for topical delivery of aminolevulinic acid or its esters include creams containing penetration enhancers and/or iron chelators, pressure sensitive patches and bioadhesive patches. Such systems aim to enhance drug delivery across the stratum corneum and keratinised debris overlying neoplastic lesions and improve subsequent protoporphyrin IX (PpIX) production. The alternative to using porphyrin precursors is the use of pre-formed photosensitisers. However, owing to their relatively high molecular weights, conventional topical application is not appropriate. Innovative strategies, such as the use of needle-free injections and microneedle arrays, bypass the stratum corneum, enabling rapid and targeted delivery not only porphyrin precursors but also pre-formed photosensitisers. This presentation will review drug delivery work published to date in the fields of PDT and PACT. In addition, the benefits of employing the latest advances in pharmaceutical technology will be highlighted.

  1. Precursors in cancer epidemiology: aligning definition and function.

    Science.gov (United States)

    Wacholder, Sholom

    2013-04-01

    A precursor of a disease is a definable pathologic state that progresses directly to disease without a known intermediate step and whose presence substantially increases the likelihood of disease. Precancers, or precursors of cancer, can help provide detail about the dynamic pathogenesis process before clinical disease. Thereby, ascertainment of properly defined precancers can increase precision of estimates and power in epidemiologic and clinical studies. Besides providing targets for direct treatment and improving tools for risk assessment in screening programs, precancers can help establish temporal ordering of cause and effect; can identify relatively homogeneous subsets of cancer that have passed through a given precancer state; and provide a basis for choosing high-risk individuals for detailed longitudinal study. Although the most appropriate definition of the precancer will vary with its function in particular research or clinical applications, the proportion of cancers that progress from the precancer and risk of cancer progressing from the precancer can be important measures of the value of a precancer in translational efforts.

  2. Procedimiento de preparación de la forma titanosilicato de la zeolita MWW utilizando MWW pura sílice como precursor y su uso

    OpenAIRE

    Corma, Avelino; Moliner Marín, Manuel

    2012-01-01

    La presente invención se refiere a un proceso de síntesis de la forma metalosilicato de la zeolita MWW que comprende, al menos, los siguientes pasos: i) Preparación del precursor MWW pura sílice calentando una mezcla que comprende, al menos, un compuesto orgánico que actúa como agente director de estructura orgánico (ADEO), al menos una fuente de silicio y agua, entre otros compuestos que puedan ser necesarios (como por ejemplo aniones fluoruro); seguido de la recup...

  3. Prediction of viral microRNA precursors based on human microRNA precursor sequence and structural features.

    Science.gov (United States)

    Kumar, Shiva; Ansari, Faraz A; Scaria, Vinod

    2009-08-20

    MicroRNAs (small approximately 22 nucleotide long non-coding endogenous RNAs) have recently attracted immense attention as critical regulators of gene expression in multi-cellular eukaryotes, especially in humans. Recent studies have proved that viruses also express microRNAs, which are thought to contribute to the intricate mechanisms of host-pathogen interactions. Computational predictions have greatly accelerated the discovery of microRNAs. However, most of these widely used tools are dependent on structural features and sequence conservation which limits their use in discovering novel virus expressed microRNAs and non-conserved eukaryotic microRNAs. In this work an efficient prediction method is developed based on the hypothesis that sequence and structure features which discriminate between host microRNA precursor hairpins and pseudo microRNAs are shared by viral microRNA as they depend on host machinery for the processing of microRNA precursors. The proposed method has been found to be more efficient than recently reported ab-initio methods for predicting viral microRNAs and microRNAs expressed by mammals.

  4. Context-dependent autoprocessing of human immunodeficiency virus type 1 protease precursors.

    Directory of Open Access Journals (Sweden)

    ChihFeng Tien

    Full Text Available HIV-1 protease autoprocessing is responsible for liberation of free mature protease (PR from the Gag-Pol polyprotein precursor. A cell-based model system was previously developed to examine the autoprocessing mechanism of fusion precursors carrying the p6*-PR miniprecursor sandwiched between various proteins or epitopes. We here report that precursor autoprocessing is context-dependent as its activity and outcomes can be modulated by sequences upstream of p6*-PR. This was exemplified by the 26aa maltose binding protein (MBP signal peptide (SigP when placed at the N-terminus of a fusion precursor. The mature PRs released from SigP-carrying precursors are resistant to self-degradation whereas those released from SigP-lacking fusion precursors are prone to self-degradation. A H69D mutation in PR abolished autoprocessing of SigP-containing fusion precursors whereas it only partially suppressed autoprocessing of fusion precursors lacking SigP. An autoprocessing deficient GFP fusion precursor with SigP exhibited a subcellular distribution pattern distinct from the one without it in transfected HeLa cells. Furthermore, a SigP fusion precursor carrying a substitution at the P1 position released the mature PR and PR-containing fragments that were different from those released from the precursor carrying the same mutation but lacking SigP. We also examined autoprocessing outcomes in viral particles produced by a NL4-3 derived proviral construct and demonstrated the existence of several PR-containing fragments along with the mature PR. Some of these resembled the SigP precursor autoprocessing outcomes. This finding of context-dependent modulation reveals the complexity of precursor autoprocessing regulation that most likely accompanies sequence variation imposed by the evolution of the upstream Gag moiety.

  5. El proyecto del Centro Cultural del Bicentenario

    OpenAIRE

    García Zuñiga, Federico

    2009-01-01

    El proyecto del Centro Cultural del Bicentenario (CCB) en el Palacio de Correos de la Ciudad Autónoma de Buenos Aires, Argentina, es una de las mayores intervenciones a realizar sobre el patrimonio edilicio argentino en las últimas décadas. El Edificio, declarado Monumento Histórico Nacional mediante Decreto 262/97, fue construido entre los años 1908 y 1928, a partir de un proyecto del arquitecto francés Norbert Maillart, autor de los Tribunales y del Colegio Nacional Buenos Aires ambos en la...

  6. Disturbances in LF radio-signals as seismic precursors

    Directory of Open Access Journals (Sweden)

    S. P. Kingsley

    2001-06-01

    Full Text Available Low Frequency (LF radio signals lie in the band 30-300 kHz. Monitoring equipment able to measure the electric strength of such signals, at field sites with very low noise levels, were designed and assembled in Italy. From 1993 onwards, the electric field strength of the MCO (216 kHz, France broadcasting station has been measured at two sites in Central Italy. At the end of 1996, radio signals from the CLT (189 kHz, Italy and the CZE (270 kHz, Czech Republic broadcasting stations were included in the measurements. During this monitoring period, evident attenuation of the electric field strength in some of the radio signals was observed at some of the receivers. The duration of the attenuation observed was several days and so it could have been related to particular meteorological conditions. On the other hand, this phenomenon could also represent precursors of moderate (3.0 =M =3.5 earthquakes that occurred near the receivers (within 50 km along the transmitter-receiver path. In this case it is possible that some local troposphere defocusing of the radio signals, produced by the pre-seismic processes, might have occurred. These observations were related only to moderate earthquakes and in these cases it may be that suitable meteorological conditions are needed to observe the effect. During February-March 1998 at one measuring site, we observed a significant increase in the CZE electric field strength. Unfortunately, the data of the other receiver could not be used in this case because of frequent interruptions in the recordings. The increase might have been a precursor of a strong earthquake (M = 5.3 that occurred on March 26, 1998 in the Umbria-Marche zone at a location over 100 km from the receiver, but which lay along the transmitter-receiver path. In this case, it is possible that an ionospheric disturbance, produced by the pre-seismic processes, might have occurred. If this pre-seismic behaviour of the LF signals could be confirmed then this

  7. Maturation of HIV envelope glycoprotein precursors by cellular endoproteases.

    Science.gov (United States)

    Moulard, M; Decroly, E

    2000-11-10

    The entry of enveloped viruses into its host cells is a crucial step for the propagation of viral infection. The envelope glycoprotein complex controls viral tropism and promotes the membrane fusion process. The surface glycoproteins of enveloped viruses are synthesized as inactive precursors and sorted through the constitutive secretory pathway of the infected cells. To be infectious, most of the viruses require viral envelope glycoprotein maturation by host cell endoproteases. In spite of the strong variability of primary sequences observed within different viral envelope glycoproteins, the endoproteolytical cleavage occurs mainly in a highly conserved domain at the carboxy terminus of the basic consensus sequence (Arg-X-Lys/Arg-Arg downward arrow). The same consensus sequence is recognized by the kexin/subtilisin-like serine proteinases (so called convertases) in many cellular substrates such as prohormones, proprotein of receptors, plasma proteins, growth factors and bacterial toxins. Therefore, several groups of investigators have evaluated the implication of convertases in viral envelope glycoprotein cleavage. Using the vaccinia virus overexpression system, furin was first shown to mediate the proteolytic maturation of both human immunodeficiency virus (HIV-1) and influenza virus envelope glycoproteins. In vitro studies demonstrated that purified convertases directly and specifically cleave viral envelope glycoproteins. Although these studies suggested the participation of several enzymes belonging to the convertases family, recent data suggest that other protease families may also participate in the HIV envelope glycoprotein processing. Their role in the physiological maturation process is still hypothetical and the molecular mechanism of the cleavage is not well documented. Crystallization of the hemagglutinin precursor (HA0) of influenza virus allowed further understanding of the molecular interaction between viral precursors and the cellular endoproteases

  8. Review of Dolomite as Precursor of Geopolymer Materials

    Directory of Open Access Journals (Sweden)

    Azimi E.A.

    2016-01-01

    Full Text Available Geopolymer is an environmentally friendly cementitious binder that does not require the existence of ordinary Portland cement (OPC. Geopolymer has many excellent advantages, including high early strength, low shrinkage, good thermal resistance and good chemical resistance. Previous commonly used materials include fly ash, clay and slag. The used of dolomite as precursor material in geopolymer field is still new and at the early stage of study. Only a few researchers have done studies on dolomite in geopolymer. Dolomite (CaMg(CO32 is abundant and generally inexpensive natural minerals. The possible use of these bulk calcium carbonate materials in improving the mechanical properties of geopolymers will therefore be of great interest. This paper summarizes some research outcomes on dolomite in geopolymer along with the potential of dolomite as geopolymer composites.

  9. Precursor Events Involving Plasmas Structures Around Collapsing Black Holes Binaries

    Science.gov (United States)

    Medvedev, M.; Coppi, B.

    2017-10-01

    The plasma structures that can exist around black hole binaries can sustain intrinsic plasma collective modes that have characteristic low frequencies related to the particle rotation frequencies around the binary system. As the collapse approaches, with the loss of angular momentum by emission of gravitational waves from the binary system we have suggested that the frequency of the fluctuating component of the gravitational potential can go through that of the intrinsic modes of the surrounding plasma structure and lead to a sharp amplification of them. Then the precursor to the event reported in Ref., tentatively identified by the Agile X- γ-ray observatory may be associated with the high energy radiation emission due to the fields produced by excitation of the proposed plasma modes. M. Tavani is thanked for bringing Ref. to our attention while Ref. was being completed. Sponsored in part by the U.S. DoE.

  10. Proteomic analysis of osteogenic differentiation of dental follicle precursor cells

    DEFF Research Database (Denmark)

    Morsczeck, Christian; Petersen, Jørgen; Völlner, Florian

    2009-01-01

    Recently, there has been an increased interest in unravelling the molecular mechanisms and cellular pathways controlling the differentiation and proliferation of human stem cell lines. Proteome analysis has proven to be an effective approach to comprehensive analysis of the regulatory network...... of differentiation. In the present study we applied 2-DE combined with capillary-LC-MS/MS analysis to profile differentially regulated proteins upon differentiation of dental follicle precursor cells (DFPCs). Out of 115 differentially regulated proteins, glutamine synthetase, lysosomal proteinase cathepsin B....... The bioinformatic analyses suggest that proteins associated with cell cycle progression and protein metabolism were down-regulated and proteins involved in catabolism, cell motility and biological quality were up-regulated. These results display the general physiological state of DFPCs before and after osteogenic...

  11. On the clinical significance of cutaneous melanoma′s precursors

    Directory of Open Access Journals (Sweden)

    Giuseppe Noto

    2012-01-01

    Full Text Available We can identify three main groups of cutaneous pigmented lesions that could be represented as melanoma precursors: (a congenital melanocytic nevi, (b dysplastic or atypical nevi, and (c acquired melanocytic nevi. The occurrence of melanoma in small and intermediate congenital melanocytic nevi is very uncommon, but there is a high risk in large congenital melanocytic nevi, in particular those arising in the so-called "bathing trunk" distribution. It is very important to distinguish the familial dysplastic nevus syndrome, which is a strong risk factor for cutaneous melanoma, from not familial (sporadic dysplastic nevus, in which the risk for melanoma would depend on the total number of melanocytic nevi, phototype, and on the relationship to environmental factors.

  12. On the clinical significance of cutaneous melanoma's precursors

    Science.gov (United States)

    Noto, Giuseppe

    2012-01-01

    We can identify three main groups of cutaneous pigmented lesions that could be represented as melanoma precursors: (a) congenital melanocytic nevi, (b) dysplastic or atypical nevi, and (c) acquired melanocytic nevi. The occurrence of melanoma in small and intermediate congenital melanocytic nevi is very uncommon, but there is a high risk in large congenital melanocytic nevi, in particular those arising in the so-called “bathing trunk” distribution. It is very important to distinguish the familial dysplastic nevus syndrome, which is a strong risk factor for cutaneous melanoma, from not familial (sporadic) dysplastic nevus, in which the risk for melanoma would depend on the total number of melanocytic nevi, phototype, and on the relationship to environmental factors. PMID:23130279

  13. Hybrid biosynthesis of roseobacticides from algal and bacterial precursor molecules.

    Science.gov (United States)

    Seyedsayamdost, Mohammad R; Wang, Rurun; Kolter, Roberto; Clardy, Jon

    2014-10-29

    Roseobacticides regulate the symbiotic relationship between a marine bacterium (Phaeobacter inhibens) and a marine microalga (Emiliania huxleyi). This relationship can be mutualistic, when the algal host provides food for the bacteria and the bacteria produce growth hormones and antibiotics for the algae, or parasitic, when the algae senesce and release p-coumaric acid. The released p-coumaric acid causes the bacteria to synthesize roseobacticides, which are nM-μM toxins for the algae. We examined the biosynthesis of roseobacticides and report that all roseobacticide precursors play critical roles during the mutualist phase of the symbiosis. Roseobacticides are biosynthesized from the algal growth promoter, the major food molecule provided by the algal cells, and the algal senescence signal that initiates the mutualist-to-parasite switch. Thus, molecules that are beneficial during mutualism are diverted to the synthesis of toxins during parasitism. A plausible mechanism for assembling roseobacticides from these molecules is proposed.

  14. Single Source Precursors for Thin Film Solar Cells

    Science.gov (United States)

    Banger, Kulbinder K.; Hollingsworth, Jennifer A.; Harris, Jerry D.; Cowen, Jonathan; Buhro, William E.; Hepp, Aloysius F.

    2002-01-01

    The development of thin film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. At NASA GRC we have focused on the development of new single source precursors (SSP) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD (chemical vapor deposition) process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV (photovoltaic) devices.

  15. Resonant infrared pulsed laser deposition of a polyimide precursor

    Energy Technology Data Exchange (ETDEWEB)

    Dygert, N L; Schriver, K E; Jr, R F Haglund [Department of Physics and Astronomy and W M Keck Foundation Free-Electron Laser Centre, Vanderbilt University, Nashville TN 37235 (United States)

    2007-04-15

    Poly(amic acid) (PAA), a precursor to polyimide, was successfully deposited on substrates without reaching curing temperature, by resonant infrared pulsed laser ablation. The PAA was prepared by dissolving pyromellitic dianhydride and 4, 4' oxidianiline in the polar solvent Nmethyl pyrrolidinone (NMP). The PAA was deposited in droplet-like morphologies when ablation occurred in air, and in string-like moieties in the case of ablation in vacuum. In the as-deposited condition, the PAA was easily removed by washing with NMP; however, once cured thermally for thirty minutes, the PAA hardened, indicating the expected thermosetting property. Plume shadowgraphy showed very clear contrasts in the ablation mechanism between ablation of the solvent alone and the ablation of the PAA, even at low concentrations. A Wavelength dependence in plume velocity was also observed.

  16. Mission and system concepts for Mars robotic precursor missions

    Science.gov (United States)

    Scoon, George E. N.; Hechler, Martin

    1993-01-01

    Mission and system design concepts reflecting the status at about the midpoint of the Marsnet phase A study are reported. The objective of Marsnet is to place three to four small stations (approximately 80 kg) on the surface of Mars to perform scientific measurements in the areas of geophysics (seismology), geology, geochemistry, mineralogy, meteorology, and exobiology. The ESA Landers will constitute part of a global network to which NASA is planning to contribute up to 16 other stations. The Mars Global Network may be seen as a precursor to the exploration of Mars by mobile vehicles in terms of its scientific measurements. But, also, some aspects of mission and system design addressed may be applicable to more complex robotic missions to Mars, for example, the development and testing of feasible probe delivery concepts; the design of low mass, low power components, and solar arrays suited for the Mars environment; and the development of a low complexity mobile instrument deployment device.

  17. Effects of Roughness and Inertia on Precursors to Frictional Sliding

    Science.gov (United States)

    Robbins, Mark O.; Salerno, K. Michael

    2012-02-01

    Experiments show that when a PMMA block on a surface is normally loaded and driven by an external shear force, contact at the interface is modified in discrete precursor slips prior to steady state sliding.[1] Our simulations use an atomistic model of a rough two-dimensional block in contact with a flat surface to investigate the evolution of stress and displacement along the contact between surfaces. The talk will show how local and global stress conditions govern the initiation of interfacial cracks as well as the spatial extension of the cracked region. Inertia also plays an important role in determining the number and size of slips before sliding and influences the distribution of stresses at the interface. Finally, the geometry of surface asperities also influences the interfacial evolution and the total friction force. The relationship between the interfacial stress state and rupture velocity will also be discussed. [1] S.M. Rubinstein, G. Cohen and J. Fineberg, PRL 98, 226103 (2007)

  18. Synthesis of S-doped graphene by liquid precursor.

    Science.gov (United States)

    Gao, Hui; Liu, Zheng; Song, Li; Guo, Wenhua; Gao, Wei; Ci, Lijie; Rao, Amrita; Quan, Weijin; Vajtai, Robert; Ajayan, Pulickel M

    2012-07-11

    Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene's lattice and mainly formed linear nanodomains, which was proved by elemental analysis, high resolution transmission microscopy and Raman spectra. Measurements on S-doped graphene field-effect transistors (G-FETs) revealed that S-doped graphene exhibited lower conductivity and distinctive p-type semiconductor properties compared with those of pristine graphene. Our approach has produced a new member in the family of graphene based materials and is promising for producing graphene based devices for multiple applications.

  19. alpha-Melanocyte-stimulating-hormone precursors in the pig pituitary

    DEFF Research Database (Denmark)

    Fenger, M

    1986-01-01

    The occurrence of intermediates from the processing of ACTH-(1-39) [adrenocorticotropic hormone-(1-39)] to alpha-melanocyte-stimulating hormone was investigated in normal pig pituitaries by the use of sensitive and specific radioimmunoassays for ACTH-(1-13), ACTH-(1-14), ACTH-(1-13)-NH2 and ACTH-(1......-39). Fractionation by reverse-phase h.p.l.c. revealed ACTH(1-17) and their acetylated analogues. The intermediate lobe contained NO-diacetyl-ACTH-(1-13)-NH2, N-acetyl-ACTH-(1-13)-NH2 and ACTH-(1-13)-NH2. In addition, the corresponding ACTH-(1-14) peptides (the glycine-extended precursor of the amidated peptides...

  20. Are saponins and sapogenins precursors of prednisolone? Preliminary results

    Directory of Open Access Journals (Sweden)

    Giuseppe Federico Labella

    2015-11-01

    Full Text Available The transformation of cortisol into prednisolone in cattle faeces was demonstrated and provided by literature, given the structural similarity of prednisolone with cortisol. In this study, we evaluated a possible neo-formation of prednisolone, as results of a faecal or environmental contamination. A saponine, α-solanine, and a sapogenin, diosgenin, were selected as possible precursors. A simple method without extraction was applied. The analyses were performed by HPLC–MSn to evaluate the possible transformations. The results showed that prednisolone was detected in the faecal suspension spiked with diosgenin at t= 8h, while cortisol was also detected at t = 24h in the sample of faeces spiked with α-solanine. In the feed and in the control samples, no transformations were observed.

  1. Selecting membranes for removing NOM and DBP precursors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, P.; Ruiz, H. (CH2M Hill, Santa Ana, CA (United States)); Thompson, K.; Spangenberg, C. (Irvine Ranch Water District, CA (United States))

    1994-12-01

    A membrane filtration pilot plant was operated for one year to evaluate the removal of natural organic matter and disinfection by-product precursors from a highly colored groundwater in Orange County, California. Two nanofiltration (NF) membranes--a traditional softening membrane and a high-permeability, charged membrane--were selected for pilot-scale testing based on bench-scale tests of eight NF and ultrafiltration membranes. The high-permeability NF membrane demonstrated superior organics removal at very high recovery and flux. It also allowed most inorganic constituents to pass through. The concentrate of low total dissolved solids reduced inorganic fouling and made concentrate reuse possible. The article also presents preliminary design criteria and a cost opinion for full-scale treatment facilities.

  2. Calibrations for studies of neutron-rich precursor fragments

    Science.gov (United States)

    Mazza, Maria; Parkhurst, Rachel; Wilensky, Samuel; Mosby, Michelle; Stephenson, Sharon; Rogers, Warren; MoNA Collaboration Collaboration

    2015-10-01

    Heavy ion collisions at relativistic energies produce the radioactive beams used at nuclear structure facilities worldwide. However, there are still unanswered questions about the reaction mechanism of projectile fragmentation and the specific roles that ablation, evaporation, and abrasion play. Using the projectile fragmentation of a 32Mg beam at 86 MeV/u on a natural Beryllium target at the National Superconducting Cyclotron Laboratory (NSCL), our experimental goal is to better understand the excitation energy and the momentum distribution of the precursors of the observed final fragments (neon, sodium, and fluorine). A suite of charged particle detectors in conjunction with the Modular Neutron Array (MoNA) allows us to analyze both the charged final fragments as well as the coincident neutrons. Detector calibration results and preliminary results will be presented. This material is based upon work supported by the National Science Foundation under Grants PHY-1205537.

  3. Ceria Nanotube Formed by Sacrificed Precursors Template through Oswald Ripening.

    Science.gov (United States)

    Pang, Laixue; Wang, Xiaoying; Tang, Xinde

    2015-01-01

    Controllable preparation of ceria nanotube was realized by hydrothermal treatment of Ce(OH)CO3 precursors. The gradually changing morphologies and microstructures of cerium oxide were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. A top-down path is illuminated to have an insight to the morphological transformation from nanorod to nanotube by adjusting the reaction time. The growth process is investigated by preparing a series of intermediate morphologies during the shape evolution of CeO2 nanostructure based on the scanning electron microscopy image observation. On the basis of the time-dependent experimental observation, the possible formation mechanism related to oriented attachment and Oswald ripening was proposed, which might afford some guidance for the synthesis of other inorganic nanotubes.

  4. Ceria Nanotube Formed by Sacrificed Precursors Template through Oswald Ripening.

    Directory of Open Access Journals (Sweden)

    Laixue Pang

    Full Text Available Controllable preparation of ceria nanotube was realized by hydrothermal treatment of Ce(OHCO3 precursors. The gradually changing morphologies and microstructures of cerium oxide were characterized by X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. A top-down path is illuminated to have an insight to the morphological transformation from nanorod to nanotube by adjusting the reaction time. The growth process is investigated by preparing a series of intermediate morphologies during the shape evolution of CeO2 nanostructure based on the scanning electron microscopy image observation. On the basis of the time-dependent experimental observation, the possible formation mechanism related to oriented attachment and Oswald ripening was proposed, which might afford some guidance for the synthesis of other inorganic nanotubes.

  5. Analysis of Amyloid Precursor Protein function in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Doris Kretzschmar

    2016-07-01

    Full Text Available The Amyloid precursor protein (APP has mainly been investigated in connection with its role in Alzheimer’s disease due to its cleavage resulting in the production of the Aβ peptides that accumulate in the plaques characteristic for this disease. However, APP is an evolutionary conserved protein that is not only found in humans but also in many other species, including Drosophila, suggesting an important physiological function. Besides Aβ, several other fragments are produced by the cleavage of APP; large secreted fragments derived from the N-terminus and a small intracellular C-terminal fragment. Although these fragments have received much less attention than Aβ, a picture about their function is finally emerging. In contrast to mammals, which express three APP family members, Drosophila expresses only one APP protein called Amyloid Precursor Protein-like or APPL. Therefore APPL functions can be studied in flies without the complication that other APP family members may have redundant functions. Flies lacking APPL are viable but show defects in neuronal outgrowth in the central and peripheral nervous system in addition to synaptic changes. Furthermore, APPL has been connected with axonal transport functions. In the adult nervous system, APPL, and more specifically its secreted fragments, can protect neurons from degeneration. APPL cleavage also prevents glial death. Lastly, APPL was found to be involved in behavioural deficits and in regulating sleep/activity patterns. This review, will describe the role of APPL in neuronal development and maintenance and briefly touch on its emerging function in circadian rhythms while an accompanying review will focus on its role in learning and memory formation.

  6. Using Groundwater physiochemical properties for assessing potential earthquake precursor

    Science.gov (United States)

    Inbar, Nimrod; Reuveni, Yuval; Anker, Yaakov; Guttman, Joseph

    2017-04-01

    Worldwide studies reports pre-seismic, co-seismic and post-seismic reaction of groundwater to earthquakes. The unique hydrological and geological situation in Israel resulted in relatively deep water wells which are located close to seismically active tectonic plate boundary. Moreover, the Israeli experience show that anomalies may occurs 60-90 minutes prior to the seismic event (Guttman et al., 2005; Anker et al., 2016). Here, we try to assess the possible connection between changes in physiochemical parameters of groundwater and earthquakes along the Dead Sea Transform (DST) region. A designated network of monitoring stations was installed in MEKOROT abandoned deep water wells, continuously measuring water table, conductivity and temperature at a sampling rate of 1 minute. Preliminary analysis compares changes in the measured parameters with rain events, tidal effects and earthquake occurrences of all measured magnitudes (>2.5Md) at monitoring area surroundings. The acquired data set over one year recorded simultaneous abrupt changes in several wells which seems disconnected from standard hydrological occurrences such as precipitation, abstraction or tidal effects. At this stage, our research aims to determine and rationalize a baseline for "normal response" of the measured parameters to external occurrences while isolating those cases in which "deviations" from that base line is recorded. We apply several analysis techniques both in time and frequency domain with the measured signal as well as statistical analysis of several measured earthquake parameters, which indicate potential correlations between earthquakes occurrences and the measured signal. We show that at least in one seismic event (5.1 Md) a potential precursor may have been recorded. Reference: Anker, Y., N. Inbar, A. Y. Dror, Y. Reuveni, J. Guttman, A. Flexer, (2016). Groundwater response to ground movements, as a tool for earthquakes monitoring and a possible precursor. 8th International Conference

  7. The Genetic Evolution of Melanoma from Precursor Lesions.

    Science.gov (United States)

    Shain, A Hunter; Yeh, Iwei; Kovalyshyn, Ivanka; Sriharan, Aravindhan; Talevich, Eric; Gagnon, Alexander; Dummer, Reinhard; North, Jeffrey; Pincus, Laura; Ruben, Beth; Rickaby, William; D'Arrigo, Corrado; Robson, Alistair; Bastian, Boris C

    2015-11-12

    The pathogenic mutations in melanoma have been largely catalogued; however, the order of their occurrence is not known. We sequenced 293 cancer-relevant genes in 150 areas of 37 primary melanomas and their adjacent precursor lesions. The histopathological spectrum of these areas included unequivocally benign lesions, intermediate lesions, and intraepidermal or invasive melanomas. Precursor lesions were initiated by mutations of genes that are known to activate the mitogen-activated protein kinase pathway. Unequivocally benign lesions harbored BRAF V600E mutations exclusively, whereas those categorized as intermediate were enriched for NRAS mutations and additional driver mutations. A total of 77% of areas of intermediate lesions and melanomas in situ harbored TERT promoter mutations, a finding that indicates that these mutations are selected at an unexpectedly early stage of the neoplastic progression. Biallelic inactivation of CDKN2A emerged exclusively in invasive melanomas. PTEN and TP53 mutations were found only in advanced primary melanomas. The point-mutation burden increased from benign through intermediate lesions to melanoma, with a strong signature of the effects of ultraviolet radiation detectable at all evolutionary stages. Copy-number alterations became prevalent only in invasive melanomas. Tumor heterogeneity became apparent in the form of genetically distinct subpopulations as melanomas progressed. Our study defined the succession of genetic alterations during melanoma progression, showing distinct evolutionary trajectories for different melanoma subtypes. It identified an intermediate category of melanocytic neoplasia, characterized by the presence of more than one pathogenic genetic alteration and distinctive histopathological features. Finally, our study implicated ultraviolet radiation as a major factor in both the initiation and progression of melanoma. (Funded by the National Institutes of Health and others.).

  8. Destrucció dels "boscos animals" del fons del mar

    OpenAIRE

    Rossi, Sergio

    2014-01-01

    L'anomenat "bosc animal", compost per gorgònies, coralls, esponges i altres organismes que viuen fixos al fons del mar, és un ecosistema amb importants funcions dins el conjunt dels oceans que està en seriós declivi a tot el planeta. La pesca, i concretament la pesca d'arrossegament, és la principal pertorbació d'aquests ecosistemes, ja que "escombra" el fons del mar i el despulla de flora i fauna. Aquest article intenta explicar els principals motius de la seva ràpida desaparició i degradaci...

  9. The control of N-nitrosodimethylamine, Halonitromethane, and Trihalomethane precursors by Nanofiltration.

    Science.gov (United States)

    Ersan, Mahmut S; Ladner, David A; Karanfil, Tanju

    2016-11-15

    Nanofiltration (NF) is a promising technology for removing precursors of disinfection byproducts (DBPs) from source waters prior to oxidant addition in water treatment. The aims of this study were to investigate (i) the removal efficiencies of N-nitrosodimethylamine (NDMA), halonitromethane (HNM), and trihalomethane (THM) precursors by NF membranes from different source water types (i.e. surface water, wastewater impacted surface water, and municipal and industrial wastewater treatment effluents), (ii) the impact of membrane type, and (iii) the effects of background water components (i.e., pH, ionic strength, and Ca(2+)) on the removal of selected DBP precursors from different source waters. The results showed the overall precursor removal efficiencies were 57-83%, 48-87%, and 72-97% for NDMA, HNM, and THM precursors, respectively. The removal of NDMA precursors decreased with the increases in average molecular weight cut off and negative surface charge of NF membranes tested, while the removal of THM precursors was slightly affected. pH changes increased the removal of NDMA precursors, but pH did not affect the removal of THM and HNM precursors in municipal WWTP effluent. On the other hand, pH changes had little or no effect on DBP removal from industrial WWTP effluent. In addition, regardless of the membrane type or background water type/characteristics, ionic strength did not show any impact on DBP precursor removals. Lastly, an increase in Ca(2+) concentration enhanced the removal of NDMA precursors while a slight decrease and no effect was observed for THM and HNM precursors, respectively, in municipal WWTP effluent. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. A Protocol for Isolation and Enriched Monolayer Cultivation of Neural Precursor Cells from Mouse Dentate Gyrus

    OpenAIRE

    Babu, Harish; Claasen, Jan-Hendrik; Kannan, Suresh; Rünker, Annette E.; Palmer, Theo; Kempermann, Gerd

    2011-01-01

    In vitro assays are valuable tools to study the characteristics of adult neural precursor cells under controlled conditions with a defined set of parameters. We here present a detailed protocol based on our previous original publication (Babu et al., 2007) to isolate neural precursor cells from the hippocampus of adult mice and maintain and propagate them as adherent monolayer cultures. The strategy is based on the use of Percoll density gradient centrifugation to enrich precursor cells from ...

  11. A protocol for isolation and enriched monolayer cultivation of neural precursor cells from mouse dentate gyrus

    OpenAIRE

    Harish eBabu; Jan-Hendrik eClaasen; Jan-Hendrik eClaasen; Jan-Hendrik eClaasen; Suresh eKannan; Annette E. Rünker; Theo ePalmer; Gerd eKempermann; Gerd eKempermann

    2011-01-01

    In vitro assays are valuable tools to study the characteristics of adult neural precursor cells under controlled conditions with a defined set of parameters. We here present a detailed protocol based on our previous original publication (Babu et al., Enriched monolayer precursor cell cultures from micro-dissected adult mouse dentate gyrus yield functional granule cell-like neurons, PLoS One 2007, 2:e388) to isolate neural precursor cells from the hippocampus of adult mice and maintain and pro...

  12. Bartonellosis, Cultivo del Tejido del Verrucoma

    OpenAIRE

    Cuadra, Manuel; Laboratorio de Virología Facultad de Medicina Universidad Nacional Mayor de San Marcos Lima, Perú

    2014-01-01

    Ha sido obtenida “in vitro” la multiplicación de las células del Verrucoma. No pudo ser localizada la Bartonella bacilliformis, ni ningún otro germen, en los cultivos (microscopía y cultivos); ni pudo ser aislada del paciente mediante hemocultivo y cultivo de fragmentos de verrucoma.

  13. Residual gas analysis of volatile impurities in halide precursors for scintillator crystals

    Science.gov (United States)

    Swider, S.; Motakef, S.; Datta, A.; Higgins, W. M.

    2013-09-01

    Alkaline-earth halides can be made into bright scintillators if purity is maintained during synthesis and growth. In order to investigate precursor purity, beaded halide precursors were heated under vacuum and evolved gas was assessed by residual gas spectroscopy. These precursors included cesium chloride, lithium chloride, yttrium chloride, cerium chloride, strontium iodide, europium iodide, barium bromide, and europium bromide. Water and CO2 desorption, sulfur release, argon release, and halide dissociation was observed in samples. Triply-oxidized precursors showed multiple paths to decomposition. The data inform approaches toward purification and growth.

  14. Lipid profiling by multiple precursor and neutral loss scanning driven by the data-dependent acquisition

    DEFF Research Database (Denmark)

    Schwudke, Dominik; Oegema, Jeffrey; Burton, Lyle

    2006-01-01

    Data-dependent acquisition of MS/MS spectra from lipid precursors enables to emulate the simultaneous acquisition of an unlimited number of precursor and neutral loss scans in a single analysis. This approach takes full advantage of rich fragment patterns in tandem mass spectra of lipids and enab......Data-dependent acquisition of MS/MS spectra from lipid precursors enables to emulate the simultaneous acquisition of an unlimited number of precursor and neutral loss scans in a single analysis. This approach takes full advantage of rich fragment patterns in tandem mass spectra of lipids...

  15. Non-invasive method for in vivo detection of chlorophyll precursors

    DEFF Research Database (Denmark)

    Kristiansen, Kim Anker; Khrouchtchova, Anastassia; Stenbæk, Anne

    2009-01-01

    Traditionally chlorophyll (Chl) and Chl precursors have been studied in vitro or in leaf tissue at low temperature. These methods are destructive and make it impossible to work with the same individual plant later on. In this paper we present a method for in vivo detection of Chl and its precursors...... in seedling plants which can be rescued for further studies. Multi-photon microscopy, which we show to be more reliable in vivo than UV-laser microscopy, is used to detect precursors in the biosynthetic pathway leading to Chl. The sensitivity and ability to distinguish different precursors with this system...

  16. Summary of ceramic pigments by polymer precursors Pechini method; Sintese de pigmentos ceramicos pelo metodo dos precursores polimericos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, E.M. da; Galvao, S.B.; Paskocimas, C.A., E-mail: everlania_siva@yahoo.com.b [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2010-07-01

    In this work were synthesized nitrate chromium nitrate and iron-doped titanium oxide by the polymeric precursor method, for application as ceramic pigments. The stains were developed between the temperatures 700 deg C to 1000 deg C, in green for chromium oxide and orange for iron. Noticing an increase of its opacity by increasing temperature. Characterization by thermogravimetry (TG) showed strong thermo decomposition from 355 deg C for the chromium oxide and thermo decomposition gradual for the iron. By analysis of X-ray diffraction revealed the formation of crystalline phases as Iron Titanate (FeTiO3) and Chrome Titanate (CrTiO3), respectively. The scanning electron microscopy showed the formation of rounded particles for both oxides. Thus, the synthesized oxides were within the requirements to be applied as pigments and shown to be possible to propose its use in ceramic materials. (author)

  17. Acerca del moho

    Science.gov (United States)

    El moho forma parte del medio ambiente natural. Afuera del hogar, el moho juega un papel en la naturaleza al desintegrar materias organicas tales como las hojas que se han caido o los arboles muertos. El moho puede crecer adentro del hogar cuando las espor

  18. Large precursor tolerance database search - a simple approach for estimation of the amount of spectra with precursor mass shifts in proteomic data.

    Science.gov (United States)

    Weng, Rueyhung Roc; Chu, Lichieh Julie; Shu, Hung-Wei; Wu, Timothy H; Chen, Mengchieh Claire; Chang, Yuwei; Tsai, Yihsuan Shannon; Wilson, Michael C; Tsay, Yeou-Guang; Goodlett, David R; Ng, Wailap Victor

    2013-10-08

    Mass measurement and precursor mass assignment are independent processes in proteomic data acquisition. Due to misassignments to C-13 peak, or for other reasons, extensive precursor mass shifts (i.e., deviations of the measured from calculated precursor neutral masses) in LC-MS/MS data obtained with the high-accuracy LTQ-Orbitrap mass spectrometers have been reported in previous studies. Although computational methods for post-acquisition reassignment to monoisotopic mass have been developed to curate the MS/MS spectra prior to database search, a simpler method for estimating the fraction of spectra with precursor mass shift so as to determine whether the data require curation remains desirable. Here, we provide the evidence that an easy approach, which applies a large precursor tolerance (2.1Da or higher) in SEQUEST search against a forward and decoy protein sequence database and then filters the data with PeptideProphet peptide identification probability (p≥0.9), could detect most of the MS/MS spectra containing inaccurate precursor masses. Furthermore, through the implementation of artificial mass shifts on 4000 randomly selected MS/MS spectra, which originally had accurate precursor mass assigned by the mass spectrometers, we demonstrated that the accuracy of the precursor mass has almost negligible influence on the efficacy and fidelity of peptide identification. Integral precursor mass shift is a known problem and thus proteomic data should be handled and analyzed properly to avoid losing important protein identification and/or quantification information. A quick and easy approach for estimating the number of MS/MS spectra with inaccurate precursor mass assignments would be helpful for evaluating the performance of the instrument, determining whether the data requires curation prior to database search or should be searched with specific search parameter(s). Here we demonstrated most of the MS/MS spectra with inaccurate mass assignments (integral or non

  19. Possible earthquake precursors revealed by LF radio signals

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2001-01-01

    Full Text Available Among radio signals, low frequency (LF radio signals lie in the band between 30–300 kHz. Monitoring equipment with the ability to measure the electric strength of such signals at field sites, were designed and assembled in Italy. From 1993 onwards, the electric field strength of the MCO (216 kHz, France broadcasting station has been collecting measurements at two sites in central Italy that were chosen according to very low noise levels. At the end of 1996, radio signals from the CLT (189 kHz, Italy and CZE (270 kHz, Czech Republic broadcasting stations were included in the measurements. Meteorological data from central Italy were also collected over the same time period in order to study the influence of weather conditions on the experimental measurements. During the monitoring period, we observed some evident attenuation of the electric field strength in some of the radio signals at some of the receivers. The duration of the attenuation observed was several days, so it could possibly be related to particular meteorological conditions. On the other hand, this phenomenon might represent precursors of moderate (3.0 M 3.5 earthquakes that occurred near the receivers (within 50 km along the transmitter-receiver path. In this case, it is possible that the pre-seismic processes could have produced irregularities in the troposphere, such as ducts, reflecting layers and scattering zones, so that some local troposphere defocusing of the radio signals might have occurred. These observations were related only to moderate earthquakes and in these cases, suitable meteorological conditions were probably needed to observe the effect. Between February – March 1998, we observed at one measuring site, a significant increase in the CZE electric field strength. Unfortunately, we could not use the data of the other receiver in this case, due to frequent interruptions in the data set. The increase might have been a precursor of the strong seismic sequence (M = 5

  20. An ESA precursor mission to human exploration of the Moon

    Science.gov (United States)

    Carpenter, James; Fisackerly, Richard; Houdou, Berengere; Pradier, Alain; de Rossa, Diego; Vanoutryve, Benjamin; Jojaghaian, Aliac; Espinasse, Sylvie; Gardini, Bruno

    2010-05-01

    The coming decades will once again see humans on the surface of the Moon. Unlike the Apollo missions of the 1960s this new lunar exploration will be an international effort, with long duration missions and a goal to pave the way for further human expansion into the solar system. Ensuring the success and sustainability of this exploration poses significant challenges for all involved. ESA is currently preparing its first contribution to this international lunar exploration effort; a lunar lander mission, which will be a precursor to a future, Ariane V launched, ESA cargo and logistics capability to the Moon. The precursor mission will demonstrate soft precision landing with hazard avoidance capabilities, which will be required by a future cargo lander. In addition the mission can be applied as a preparation for future human exploration activities and help to ensure the sustainability of future exploration efforts. Activities have included Phase A and B1 mission design studies and technology development activities (both reported in another paper) and the definition of mission objectives and a model payload. The mission objectives have been derived by the Lunar Exploration Definition Team, a group derived of European specialists in various areas of exploration related science and technology, supported by ESA. Major inputs to the definition process were the 195 responses received to a request for information for potential payload contributions to the mission. The group was tasked with establishing how such a mission could best prepare for future human exploration. It was determined that the mission's goal should be to enable sustainable exploration and objectives were identified within a number of themes: health, habitation, resources, mobility and scientific preparations for future human activities. Investigations seek to characterise the lunar environment (e.g. radiation, dust etc.) and its effects and the properties of a landing site (potential resources, geological

  1. NASA Accident Precursor Analysis Handbook, Version 1.0

    Science.gov (United States)

    Groen, Frank; Everett, Chris; Hall, Anthony; Insley, Scott

    2011-01-01

    accident precursors by evaluating anomaly occurrences for their system safety implications and, through both analytical and deliberative methods used to project to other circumstances, identifying those that portend more serious consequences to come if effective corrective action is not taken. APA builds upon existing safety analysis processes currently in practice within NASA, leveraging their results to provide an improved understanding of overall system risk. As such, APA represents an important dimension of safety evaluation; as operational experience is acquired, precursor information is generated such that it can be fed back into system safety analyses to risk-inform safety improvements. Importantly, APA utilizes anomaly data to predict risk whereas standard reliability and PRA approaches utilize failure data which often is limited and rare.

  2. Ozone treatment affects pigment precursor metabolism in pine seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Shamay, Y.; Raskin, V.I.; Marder, J.B.; Schwartz, A. [the Hebrew Univ. of Jerusalem, Dept. of Agricultural Botany, Rehovot (Israel); Steinberger, H.E. [The Hebrew Uiv. of Jerusalem, Inst. of Earth Sciences, Jerusalem (Israel); Brandis, A.S. [The Weizmann Inst. of Science, Dept. of Plant Sciences, Rehovot (Israel)

    2001-07-01

    Five-week-old seedlings of Pinus halepensis Mill. and Pinus brutia Ten. were exposed to air polluted with ozone (O{sub 3}) (250 nl l{sup -)}, 12 h day{sup -1} for 4 days) or to ambient air containing ca 10-20 nl l{sup -)} O{sub 3}, in the light (180 {mu}mol m{sup -2} s{sup -1} photosynthetic photon flux density [PPFD], 12 h day{sup -1}) and then fed for 24 h in the light (100 {mu}mol m{sup -2} s{sup -1} PPFD) with various radioactive precursors of chlorophyll (Chl) and carotene biosynthesis: 5-[4-{sup 14}C]-aminolevulinic acid ({sup 14}C-ALA), L-[{sup 14}C(U)]-glutamic acid ({sup 14}C-Glu), or D,L-[2-{sup 14}C]-mevalonic acid ({sup 14}C-MVA). Pigments were then extracted from cotyledons and fully expanded needles. Chl a and carotene were separated by thin-layer chromatography and high-performance liquid chromatography and their specific activities were determined. {sup 14}C-ALA and {sup 14}C-Glu labels were incorporated into Chl a and carotene. Exposure to O{sub 3} did not inhibit incorporation of {sup 14}C-ALA into Chl a molecules, but hydrolysis of Chl a showed that O{sub 3} inhibited phytol labelling of Chl a. Labelling of carotene was also inhibited by O{sub 3}, but not when {sup 14}C-MVA was used as the label. These data suggest that O{sub 3} treatment inhibits (directly or indirectly) the biosynthesis of isoprenoids from products of ALA and Glu metabolism in the plastid, but not from MVA in the cytosol. This inhibition was more prominent when {sup 14}C-ALA was used as the label than when {sup 14}C-Glu was the labelling precursor. A significant increase in pheophorbide a, a tetrapyrrole component of Chl a labelling, and a concomitant decrease in phytol labelling was observed following incubation of O{sub 3}-treated pine seedlings with {sup 14}C-ALA and {sup 14}C-Glu. Stronger inhibition of carotene biosynthesis and activation of Chl a tetrapyrrole labelling by {sup 14}C-ALA (in comparison with {sup 14}C-Glu) indicated that exposure to O{sub 3} inhibits the

  3. Los nudos del sistema

    OpenAIRE

    Cuéllar-Garza, José L.

    2000-01-01

    Pieza central del antiguo régimen; pacto, acuerdo o trato con algunos actores decisivos del sistema político susceptible de ser revisado; forma cultural de relaciones de poder o de intercambio; pirámide de organizaciones o estructura sectorial: ¿qué tan invisible sigue siendo, qué tan montada sigue estando la pirámide del corporativismo mexicano antes y después del 2 de julio de 2000? Este fenómeno constituye el eje central de las reflexiones del presente ensayo. En torno al mismo, se pres...

  4. Manuel Larraín y la conciencia eclesial latinoamericana: Visión y legado de un precursor

    Directory of Open Access Journals (Sweden)

    Fernando Berríos

    2009-01-01

    Full Text Available Manuel Larraín Errázuriz, obispo de Talca, Chile, entre 1938 y 1966, es una de las principales figuras de la Iglesia latinoamericana del siglo XX y uno de los más importantes precursores del Concilio Vaticano II en este continente, sobre todo por su actitud de apertura a los desafíos y complejidades del mundo moderno desde una profunda fidelidad al Evangelio. El artículo busca destacar su aporte, en ese horizonte, a la conformación de una conciencia eclesial auténticamente latinoamericana. La primera parte es una presentación del catolicismo chileno tradicional en que él se formó y que más tarde se abriría a perspectivas más amplias por diversos influjos históricos. La segunda parte se refiere a cuatro grandes temas y circunstancias en los que Manuel Larraín jugó un destacado rol como pastor, forjando así esa conciencia eclesial que ha quedado como su principal legado. El texto concluye con una breve reflexión sobre este legado y sobre los desafíos que él plantea hasta hoy a la Iglesia del continente.Manuel Larraín Errázuriz, bishop of Talca, Chile, between 1938 and 1966, is one of the principal figures of the Latin American Church in the 20th century, and one of the most important forerunners of Vatican Council II on this continent, above all for the openness of his attitude while facing the challenges and complexities of the modern world from a position of deep faithfulness to the Gospel. This article seeks to emphasize his contribution, on that horizon, to the conformation of an authentically Latin American ecclesial consciousness. The first part of this article is a presentation of the traditional Chilean Catholicism in which he was brought up and which, later on, would open itself to wider perspectives thanks to different historical influences. The second part refers to four great themes and the circumstances in which Manuel Larraín played an important role as pastor, thus forging that ecclesial consciousness which

  5. Fabricación y comportamiento de espumas de aluminio con diferente densidad a partir de un precursor AlSi12

    Directory of Open Access Journals (Sweden)

    Gutiérrez-Vázquez, J. A.

    2010-06-01

    Full Text Available Closed cell aluminium foams were prepared by powder metallurgical method in three different ranges of density using AlSi12 precursor. The objective has been to determine by means of tests the effect that has the density of these materials regarding its mechanical behaviour. The used precursor contained 0.4% of foaming agent of titanium hydride (TiH2, mixed with aluminum and silicon in appropriate amounts to achieve the commercial composition of the AlSi12 precursor. Once cut the samples thermal treatments of foaming were made of 630 °C to 750 °C, by 3 to 20 minutes. The best solidification conditions were determined to avoid the collapse by means of forced air. The samples were prepared with the same weight to different densities, having itself obtained that the best mechanical behaviour was achieved in the high density foams, of 0.70 to 0.81 g/cm3.

    Se han fabricado espumas de aluminio de poro cerrado, de tres diferentes rangos de densidad, utilizando un precursor AlSi12 producido por pulvimetalurgia. El objetivo ha sido determinar el efecto que tiene la densidad de estos materiales respecto a su comportamiento mecánico. El precursor utilizado contenía un 0,4 % de hidruro de titanio (TiH2 como agente espumante, mezclado con aluminio y silicio en cantidades adecuadas para lograr la composición comercial del precursor AlSi12. Una vez cortadas las muestras, se efectuaron tratamientos térmicos de espumación entre 630 y 750 °C, a tiempos de espumación variables entre 3 y 20 min. Se determinaron las mejores condiciones de solidificación para evitar el colapso mediante aire forzado. Las muestras se prepararon con el mismo peso a diferentes densidades, habiéndose obtenido, que el mejor comportamiento mecánico se lograba en las espumas de mayor densidad, comprendidas entre 0,70 y 0,81 g/cm3.

  6. Ubiquilin 1 modulates amyloid precursor protein trafficking and Abeta secretion.

    Science.gov (United States)

    Hiltunen, Mikko; Lu, Alice; Thomas, Anne V; Romano, Donna M; Kim, Minji; Jones, Phill B; Xie, Zhongcong; Kounnas, Maria Z; Wagner, Steven L; Berezovska, Oksana; Hyman, Bradley T; Tesco, Giuseppina; Bertram, Lars; Tanzi, Rudolph E

    2006-10-27

    Ubiquilin 1 (UBQLN1) is a ubiquitin-like protein, which has been shown to play a central role in regulating the proteasomal degradation of various proteins, including the presenilins. We recently reported that DNA variants in UBQLN1 increase the risk for Alzheimer disease, by influencing expression of this gene in brain. Here we present the first assessment of the effects of UBQLN1 on the metabolism of the amyloid precursor protein (APP). For this purpose, we employed RNA interference to down-regulate UBQLN1 in a variety of neuronal and non-neuronal cell lines. We demonstrate that down-regulation of UBQLN1 accelerates the maturation and intracellular trafficking of APP, while not interfering with alpha-, beta-, or gamma-secretase levels or activity. UBQLN1 knockdown increased the ratio of APP mature/immature, increased levels of full-length APP on the cell surface, and enhanced the secretion of sAPP (alpha- and beta-forms). Moreover, UBQLN1 knockdown increased levels of secreted Abeta40 and Abeta42. Finally, employing a fluorescence resonance energy transfer-based assay, we show that UBQLN1 and APP come into close proximity in intact cells, independently of the presence of the presenilins. Collectively, our findings suggest that UBQLN1 may normally serve as a cytoplasmic "gatekeeper" that may control APP trafficking from intracellular compartments to the cell surface. These findings suggest that changes in UBQLN1 steady-state levels affect APP trafficking and processing, thereby influencing the generation of Abeta.

  7. Cathepsins B and L differentially regulate amyloid precursor protein processing.

    Science.gov (United States)

    Klein, Donna M; Felsenstein, Kevin M; Brenneman, Douglas E

    2009-03-01

    Previous studies have shown that cathepsins control amyloid beta (Abeta) levels in chromaffin cells via a regulated secretory pathway. In the present study, this concept was extended to investigations in primary hippocampal neurons to test whether Abeta release was coregulated by cathepsins and electrical activity, proposed components of a regulated secretory pathway. Inhibition of cathepsin B (catB) activity with CA074Me or attenuation of catB expression through small interfering RNA produced decreases in Abeta release, similar to levels produced with suppression of beta-site APP-cleaving enzyme 1 (BACE1) expression. To test whether the catB-dependent release of Abeta was linked to ongoing electrical activity, neurons were treated with tetrodotoxin (TTX) and CA074Me. These comparisons demonstrated no additivity between decreases in Abeta release produced by TTX and CA074Me. In contrast, pharmacological inhibition of cathepsin L (catL) selectively elevated Abeta42 levels but not Abeta40 or total Abeta. Mechanistic studies measuring C-terminal fragments of amyloid precursor protein (APP) suggested that catL elevated alpha-secretase activity, thereby suppressing Abeta42 levels. The mechanism of catB-mediated regulation of Abeta release remains unclear but may involve elevation of beta-secretase. In summary, these studies provide evidence for a significant alternative pathway for APP processing that involves catB and activity-dependent release of Abeta in a regulated secretory pathway for primary neurons.

  8. Sulfate radicals enable a non-enzymatic Krebs cycle precursor.

    Science.gov (United States)

    Keller, Markus A; Kampjut, Domen; Harrison, Stuart A; Ralser, Markus

    2017-03-13

    The evolutionary origins of the Krebs cycle (tricarboxylic acid cycle) are not currently clear. Despite the existence of a simple non-enzymatic Krebs cycle catalyst being dismissed only a few years ago as 'an appeal to magic', citrate and other intermediates have since been discovered on a carbonaceous meteorite and do interconvert non-enzymatically. To identify a metabolism-like non-enzymatic Krebs cycle catalyst, we used combinatorial, quantitative high-throughput metabolomics to systematically screen iron and sulfate compounds in a reaction mixture that orients on the typical components of Archaean sediment. Krebs cycle intermediates were found to be stable in water and in the presence of most molecule species, including simple iron sulfate minerals. However, in the presence of sulfate radicals generated from peroxydisulfate, the intermediates underwent 24 interconversion reactions. These non-enzymatic reactions covered the critical topology of the oxidative Krebs cycle, the glyoxylate shunt and the succinic-semialdehyde pathway. Assembled in a chemical network, the reactions achieved over 90% carbon recovery. Our results show that a non-enzymatic precursor of the Krebs cycle is biologically sensible, efficient, and forms spontaneously in the presence of sulfate radicals.

  9. Learning from Trending, Precursor Analysis, and System Failures

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, R. W. [Idaho National Laboratory, Idaho Falls, ID (United States); Duffey, R. B. [Idaho National Laboratory, Idaho Falls, ID (United States)

    2015-11-01

    Models of reliability growth relate current system unreliability to currently accumulated experience. But “experience” comes in different forms. Looking back after a major accident, one is sometimes able to identify previous events or measurable performance trends that were, in some sense, signaling the potential for that major accident: potential that could have been recognized and acted upon, but was not recognized until the accident occurred. This could be a previously unrecognized cause of accidents, or underestimation of the likelihood that a recognized potential cause would actually operate. Despite improvements in the state of practice of modeling of risk and reliability, operational experience still has a great deal to teach us, and work has been going on in several industries to try to do a better job of learning from experience before major accidents occur. It is not enough to say that we should review operating experience; there is too much “experience” for such general advice to be considered practical. The paper discusses the following: 1. The challenge of deciding what to focus on in analysis of operating experience. 2. Comparing what different models of learning and reliability growth imply about trending and precursor analysis.

  10. The Effect of a Cosmic Ray Precursor in SN 1006?

    Science.gov (United States)

    Rakowski, Cara E.; Laming, J. Martin; Hwang, Una; Eriksen, Kristoffer A.; Ghavamian, Parviz; Hughes, John P.

    2011-07-01

    Like many young supernova remnants, SN 1006 exhibits what appear to be clumps of ejecta close to or protruding beyond the main blast wave. In this Letter, we examine three such protrusions along the east rim. They are semi-aligned with ejecta fingers behind the shock-front and exhibit emission lines from O VII and O VIII. We first interpret them in the context of an upstream medium modified by the saturated non-resonant Bell instability which enhances the growth of Rayleigh-Taylor instabilities when advected post-shock. We discuss their apparent periodicity if the spacing is determined by properties of the remnant or by a preferred size scale in the cosmic ray precursor. We also briefly discuss the alternative that these structures have an origin in the ejecta structure of the explosion itself. In this case, the young evolutionary age of SN 1006 would imply density structure within the outermost layers of the explosion with potentially important implications for deflagration and detonation in thermonuclear supernova explosion models.

  11. Selective Behaviour of Honeybees in Acquiring European Propolis Plant Precursors.

    Science.gov (United States)

    Isidorov, Valery A; Bakier, Sławomir; Pirożnikow, Ewa; Zambrzycka, Monika; Swiecicka, Izabela

    2016-06-01

    Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly.

  12. Chemical precursors to zinc sulfide: ZnS whisker synthesis

    Science.gov (United States)

    Guiton, T. A.; Czekaj, C. L.; Rau, M. S.; Geoffroy, G. L.; Pantano, C. G.

    1988-07-01

    Currently, Chemical Vapor Deposition (CVD) derived zinc sulfide is one of the most widely used infrared optical window materials. Unfortunately, for numerous applications it does not possess optimum mechanical properties. To fabricate infrared transmitting ZnS/ZnS composites requires the development of high aspect ratio, micron sized ZnS whiskers. Although larger ZnS single crystals and whiskers have been made by a variety of high temperature routes, alternative routes have been sought for greater ZnS whisker morphology control. Low temperature organometallic routes are attractive for this purpose. The precursor compound used in this study is the known pentameric species (EtZn(SBut))5. One of the most successful routes involves the reaction of (EtZn(SBU sup t))5 with hydrogen sulfide at ambient or sub-ambient temperature to yield a precipitate which is subsequently heated under flowing H2S at 500 C to yield a mixture of sub-micron particles and single-crystal ZnS whiskers. Transmission electron micrographs of the (EtZn(SBU sup t))5 products indicate that the ZnS morphology is critically dependent on the rate of H2S reaction. Corresponding X-ray/electron diffraction, electron microscopy, elemental analysis, NMR and infrared spectroscopies have been conducted. A summary of the chemical methods, product characterization results, and proposed synthesis mechanisms are presented.

  13. Nonlinear softening as a predictive precursor to climate tipping.

    Science.gov (United States)

    Sieber, Jan; Thompson, J Michael T

    2012-03-13

    Approaching a dangerous bifurcation, from which a dynamical system such as the Earth's climate will jump (tip) to a different state, the current stable state lies within a shrinking basin of attraction. Persistence of the state becomes increasingly precarious in the presence of noisy disturbances. We argue that one needs to extract information about the nonlinear features (a 'softening') of the underlying potential from the time series to judge the probability and timing of tipping. This analysis is the logical next step if one has detected a decrease of the linear decay rate. If there is no discernible trend in the linear analysis, nonlinear softening is even more important in showing the proximity to tipping. After extensive normal-form calibration studies, we check two geological time series from palaeo-climate tipping events for softening of the underlying well. For the ending of the last ice age, where we find no convincing linear precursor, we identify a statistically significant nonlinear softening towards increasing temperature.

  14. A five-factor model of developmental personality pathology precursors.

    Science.gov (United States)

    Verbeke, Lize; De Caluwé, Elien; De Clercq, Barbara

    2017-04-01

    There is growing consensus that the dimensional structure of early personality pathology can be organized within a similar framework as in adults (De Clercq, De Fruyt, Van Leeuwen, & Mervielde, 2006; Tromp & Koot, 2008). From this perspective, the Dimensional Personality Symptom Itempool (DIPSI) was recently expanded from a 4- to a 5-dimensional trait structure (Verbeke & De Clercq, 2014), including Disagreeableness, Emotional Instability, Introversion, Compulsivity, and Oddity. This developmental maladaptive trait structure is in need of further research, however, before it can be accepted as a valid framework for describing early manifestations of personality dysfunction. By use of exploratory structural equation modeling (ESEM) analyses, the current study explored the fit of the 5-factor DIPSI framework across 4 different samples (N = 1456), and replicated 5 higher-order factors that demonstrated scalar invariance across age and metric invariance across informants and clinical status. These results underscore the robustness of 5 underlying dimensions of personality pathology at a young age and highlight adequate psychometric properties of the proposed DIPSI measure for describing childhood personality pathology precursors. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  15. HI-SCALE Nanoparticle Composition and Precursors Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James [Univ. of California, Irvine, CA (United States); Stark, Harald [Aerodyne Research, Inc., Billerica, MA (United States); Browne, Eleanor [Univ. of Colorado, Boulder, CO (United States); Hanson, David [Augsburg College, Minneapolis, MN (United States)

    2017-06-15

    From 21 August to 27 September, 2016, during the second Intensive Operational Period (IOP) of the Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecoystems (HI-SCALE) field campaign, a suite of instruments were placed in the Guest Instrument Facility (GIF) at the Central Facility of the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site in Lamont, Oklahoma. The goal of these measurements was to fully characterize the formation and evolution of atmospheric aerosol particles through measurements of gas-phase precursor and ambient nanoparticle composition. Specifically, we sought to: 1. investigate the role of acid-base chemistry in new-particle growth through measurements of ammonia and amines as well as organic and inorganic acids in both atmospheric nanoparticles and the gas phase; 2. investigate the contribution of other surface-area or volume-controlled processes to nanoparticle formation and growth, such as the uptake of extremely low volatility organic compounds (ELVOCs); 3. evaluate the performance of a new instrument being developed with funding from the DOE Small Business Innovation Research (SBIR) program for measuring gas-phase amines and related compounds; and 4. together with colleagues measuring on the ground and onboard the ARM Gulfstream-1 (G-1) aircraft during HI-SCALE, create a comprehensive data set related to new particle formation and growth that can be used in modeling efforts by the research team as well as DOE collaborators.

  16. Isolation, characterization, and aggregation of a structured bacterial matrix precursor.

    Science.gov (United States)

    Chai, Liraz; Romero, Diego; Kayatekin, Can; Akabayov, Barak; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

    2013-06-14

    Biofilms are surface-associated groups of microbial cells that are embedded in an extracellular matrix (ECM). The ECM is a network of biopolymers, mainly polysaccharides, proteins, and nucleic acids. ECM proteins serve a variety of structural roles and often form amyloid-like fibers. Despite the extensive study of the formation of amyloid fibers from their constituent subunits in humans, much less is known about the assembly of bacterial functional amyloid-like precursors into fibers. Using dynamic light scattering, atomic force microscopy, circular dichroism, and infrared spectroscopy, we show that our unique purification method of a Bacillus subtilis major matrix protein component results in stable oligomers that retain their native α-helical structure. The stability of these oligomers enabled us to control the external conditions that triggered their aggregation. In particular, we show that stretched fibers are formed on a hydrophobic surface, whereas plaque-like aggregates are formed in solution under acidic pH conditions. TasA is also shown to change conformation upon aggregation and gain some β-sheet structure. Our studies of the aggregation of a bacterial matrix protein from its subunits shed new light on assembly processes of the ECM within bacterial biofilms.

  17. Molecular crystals as precursors for poly-nitrogen

    Science.gov (United States)

    Borstad, Gustav; Ciezak-Jenkins, Jennifer

    The application of pressure to matter results in dramatic modifications of its properties. The compression of molecular crystals first eliminates ``empty'' space between the molecules. It then alters the electron density distribution, favoring the increase of atomic coordination and the formation of polymers. The polymerization of low-Z compounds into covalently-bonded networks in three dimensions tend to generate materials characterized by superconductivity, super-hardness, and high-energy density.1 Poly-nitrogen (analogous to diamond) has been synthesized under extreme conditions above 100 GPa and 2000 K in diamond anvil cells, but could not be recovered to ambient conditions.2 A useful form of poly-nitrogen would have to be synthesized at low-pressure with enhanced stability at ambient conditions. The changes in the intermolecular and intramolecular interactions with pressure play a crucial role in the synthesizing and stabilizing of the structure as well as in tuning its properties. In this talk, we provide Raman and x-ray diffraction data on nitrogen-containing compound biuret and compare it to work on other possible poly-nitrogen precursors. During this project, coauthor GB was supported in part by an appointment to the Postdoctoral Research Program at the US Army Research Laboratory administered by the Oak Ridge Associated Universities.

  18. Synthesis and Mechanism of Tetracalcium Phosphate from Nanocrystalline Precursor

    Directory of Open Access Journals (Sweden)

    Jianguo Liao

    2014-01-01

    Full Text Available Tetracalcium phosphate (TTCP, Ca4(PO42O was prepared by the calcination of coprecipitated mixture of nanoscale hydroxyapatite (HA, Ca10(PO46(OH2 and calcium carbonate crystal (CaCO3, followed by cooling in the air or furnace. The effect of calcination temperature on crystal structure and phase composition of the coprecipitation mixture was characterized by transmission electron microscope (TEM, thermal analysis-thermogravimetry (DTA-TG, X-ray diffraction (XRD, Fourier transform-infrared spectroscopy (FT-IR, and Raman spectroscopy (RS. The obtained results indicated that the synthesized mixture consisted of nanoscale HA and CaCO3 with uniform distribution throughout the composite. TTCP was observed in the air quenching samples when the calcination temperature was above 1185°C. With the increase of the calcination temperature, the amount of the intermediate products in the air quenching samples decreased and cannot be detected when calcination temperature reached 1450°C. Unexpectedly, the mixture of HA and calcium oxide was observed in the furnace cooling samples. Clearly, the calcination temperature and cooling methods are critical for the synthesis of high-purity TTCP. The results indicate that the nanosize of precursors can decrease the calcination temperature, and TTCP can be calcinated by low temperature.

  19. Alterations in hippocampal myelin and oligodendrocyte precursor cells during epileptogenesis.

    Science.gov (United States)

    Luo, Yuanyuan; Hu, Qiao; Zhang, Qian; Hong, Siqi; Tang, Xiaoju; Cheng, Li; Jiang, Li

    2015-11-19

    Recent reports have described damage to myelinated fibers in the central nervous system (CNS) in patients with temporal lobe epilepsy (TLE) and animal models. However, only limited data are available on the dynamic changes that occur in myelinated fibers, oligodendrocytes (which are myelin-forming cells), and oligodendrocyte precursor cells (OPCs), which are a reservoir of new oligodendrocytes, in the hippocampus throughout epileptogenesis. The current study was designed to examine this issue using a rat model of lithium-pilocarpine-induced epilepsy. Electroencephalography (EEG), immunofluorescence, and Western blot analysis showed that the loss of myelin and oligodendrocytes in the rat hippocampus began during the acute stage of epileptogenesis, and the severity of this loss increased throughout epileptogenesis. Accompanying this loss of myelin and oligodendrocytes, OPCs in the rat hippocampus became activated and their populations increased during several phases of epileptogenesis (the acute, latent and chronic phases). The transcription factors olig1 and olig2, which play crucial roles in regulating OPC proliferation, differentiation and remyelination, were up-regulated during the early phases (the acute and latent phases) followed by a sharp decline in their expression during the chronic and late chronic phases. This study is the first to confirm the loss of myelin and oligodendrocytes during lithium-pilocarpine-induced epileptogenesis accompanied by a transient increase in the number of OPCs. Prevention of the loss of myelin and oligodendrocytes may provide a novel treatment strategy for epilepsy. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Sentinel-5 Precursor: First Copernicus Atmospheric Mission Ready for Launch

    Science.gov (United States)

    McMullan, Kevin; Nett, Herbert; Fehr, Thorsten; Ingmann, Paul

    2016-08-01

    Sentinel-5 Precursor (S-5P) will be the first of a series of atmospheric missions to be launched within the European Commission's Copernicus (former GMES) Programme. With the current launch window mid October - mid November 2016 and a nominal lifetime of 7 years S-5P is expected to provide continuity in the availability of global atmospheric data products between its predecessor missions SCIAMACHY (Envisat) and OMI (AURA) and the future Sentinel-4 and -5 series.S-5P will deliver unique data regarding the sources and sinks of trace gases with a focus on the lower Troposphere including the planet boundary layer. Due to its enhanced spatial, temporal and spectral sampling capabilities, as compared to its predecessors.The S-5P satellite will carry a single payload, TROPOMI (TROPOspheric Monitoring Instrument) which is jointly developed by The Netherlands and ESA. Covering spectral channels in the UV, visible, near- and short-wave infrared it will measure various key species including tropospheric/stratospheric ozone, NO2, SO2, CO, CH4, CH2O as well as cloud and aerosol parameters.The S-5P Project has successfully passed the Ground Segment Acceptance Review (GS-AR) and the satellite level Qualification Acceptance Review (QAR) in March and April 2016, respectively. Remaining pre-launch tasks focus on the detailed planning of Phase E1 activities and the training of the operations teams.

  1. Role of Drosophila Amyloid Precursor Protein in Memory Formation

    Directory of Open Access Journals (Sweden)

    Thomas Preat

    2016-12-01

    Full Text Available The amyloid precursor protein (APP is a membrane protein engaged in complex proteolytic pathways. APP and its derivatives have been shown to play a central role in Alzheimer’s disease (AD, a progressive neurodegenerative disease characterized by memory decline. Despite huge effort from the research community, the primary cause of AD remains unclear, making it crucial to better understand the physiological role of the APP pathway in brain plasticity and memory. Drosophila melanogaster is a model system well-suited to address this issue. Although relatively simple, the fly brain is highly organized, sustains several forms of learning and memory, and drives numerous complex behaviors. Importantly, molecules and mechanisms underlying memory processes are conserved from flies to mammals. The fly encodes a single non-essential APP homolog named APP-Like (APPL. Using in vivo inducible RNA interference strategies, it was shown that APPL knockdown in the mushroom bodies—the central integrative brain structure for olfactory memory—results in loss of memory. Several APPL derivatives, such as secreted and full-length membrane APPL, may play different roles in distinct types of memory phases. Furthermore, overexpression of Drosophila amyloid peptide exacerbates the memory deficit caused by APPL knockdown, thus potentiating memory decline. Data obtained in the fly support the hypothesis that APP acts as a transmembrane receptor, and that disruption of its normal function may contribute to cognitive impairment during early AD.

  2. Dry Powder Precursors of Cubic Liquid Crystalline Nanoparticles (cubosomes)

    Science.gov (United States)

    Spicer, Patrick T.; Small, William B.; Small, William B.; Lynch, Matthew L.; Burns, Janet L.

    2002-08-01

    Cubosomes are dispersed nanostructured particles of cubic phase liquid crystal that have stimulated significant research interest because of their potential for application in controlled-release and drug delivery. Despite the interest, cubosomes can be difficult to fabricate and stabilize with current methods. Most of the current work is limited to liquid phase processes involving high shear dispersion of bulk cubic liquid crystalline material into sub-micron particles, limiting application flexibility. In this work, two types of dry powder cubosome precursors are produced by spray-drying: (1) starch-encapsulated monoolein is produced by spray-drying a dispersion of cubic liquid crystalline particles in an aqueous starch solution and (2) dextran-encapsulated monoolein is produced by spray-drying an emulsion formed by the ethanol-dextran-monoolein-water system. The encapsulants are used to decrease powder cohesion during drying and to act as a soluble colloidal stabilizer upon hydration of the powders. Both powders are shown to form (on average) 0.6 μm colloidally-stable cubosomes upon addition to water. However, the starch powders have a broader particle size distribution than the dextran powders because of the relative ease of spraying emulsions versus dispersions. The developed processes enable the production of nanostructured cubosomes by end-users rather than just specialized researchers and allow tailoring of the surface state of the cubosomes for broader application.

  3. Silicon deposition in nanopores using a liquid precursor

    Science.gov (United States)

    Masuda, Takashi; Tatsuda, Narihito; Yano, Kazuhisa; Shimoda, Tatsuya

    2016-11-01

    Techniques for depositing silicon into nanosized spaces are vital for the further scaling down of next-generation devices in the semiconductor industry. In this study, we filled silicon into 3.5-nm-diameter nanopores with an aspect ratio of 70 by exploiting thermodynamic behaviour based on the van der Waals energy of vaporized cyclopentasilane (CPS). We originally synthesized CPS as a liquid precursor for semiconducting silicon. Here we used CPS as a gas source in thermal chemical vapour deposition under atmospheric pressure because vaporized CPS can fill nanopores spontaneously. Our estimation of the free energy of CPS based on Lifshitz van der Waals theory clarified the filling mechanism, where CPS vapour in the nanopores readily undergoes capillary condensation because of its large molar volume compared to those of other vapours such as water, toluene, silane, and disilane. Consequently, a liquid-specific feature was observed during the deposition process; specifically, condensed CPS penetrated into the nanopores spontaneously via capillary force. The CPS that filled the nanopores was then transformed into solid silicon by thermal decomposition at 400 °C. The developed method is expected to be used as a nanoscale silicon filling technology, which is critical for the fabrication of future quantum scale silicon devices.

  4. The HIV Tat protein affects processing of ribosomal RNA precursor

    Directory of Open Access Journals (Sweden)

    Bellenchi Gian

    2008-06-01

    Full Text Available Abstract Background Inside the cell, the HIV Tat protein is mainly found in the nucleus and nucleolus. The nucleolus, the site of ribosome biogenesis, is a highly organized, non-membrane-bound sub-compartment where proteins with a high affinity for nucleolar components are found. While it is well known that Tat accumulates in the nucleolus via a specific nucleolar targeting sequence, its function in this compartment it still unknown. Results To clarify the significance of the Tat nucleolar localization, we induced the expression of the protein during oogenesis in Drosophila melanogaster strain transgenic for HIV-tat gene. Here we show that Tat localizes in the nucleoli of Drosophila oocyte nurse cells, where it specifically co-localizes with fibrillarin. Tat expression is accompanied by a significant decrease of cytoplasmic ribosomes, which is apparently related to an impairment of ribosomal rRNA precursor processing. Such an event is accounted for by the interaction of Tat with fibrillarin and U3 snoRNA, which are both required for pre-rRNA maturation. Conclusion Our data contribute to understanding the function of Tat in the nucleolus, where ribosomal RNA synthesis and cell cycle control take place. The impairment of nucleolar pre-rRNA maturation through the interaction of Tat with fibrillarin-U3snoRNA complex suggests a process by which the virus modulates host response, thus contributing to apoptosis and protein shut-off in HIV-uninfected cells.

  5. Microplasma copolymerization of amine and Si containing precursors

    Energy Technology Data Exchange (ETDEWEB)

    Bashir, M., E-mail: m.bashir@comsats.edu.pk [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom); Rees, Julia M.; Bashir, S. [School of Mathematics and Statistics, Hicks Building, Hounsfield Road, University of Sheffield, S3 7RH (United Kingdom); Zimmerman, William B. [Department of Chemical and Biological Engineering and Kroto Research Institute, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2014-08-01

    We report a technique of microplasma copolymerization for depositing a stable amino functional film on the inner walls of a glass microcapillary. The monomers ethylenediamine (EDA), 3 aminopropyltriethoxysilane (APTS) and hexamethyldisiloxane (HMDSO) were used as organic precursors for copolymerization. The ratio of the monomer mixture in the plasma was precisely fed using an original technique of liquid injection and helical mixing. The coatings obtained from EDA–HMDSO were found to be more stable than those produced using EDA and APTS. The films were characterized using X-ray photoelectron, Fourier transform infrared and UV–vis spectroscopy, atomic force microscopy and growth rate measurements. The hydrophobic and hydrophilic characteristics of the films were analyzed through water contact angle and surface free energy measurements. The stability of the coatings formed using this method in aqueous media indicated that they could be utilized for biological and microfluidic applications. - Highlights: • An atmospheric pressure microplasma was generated in a rectangular glass capillary. • Surface coating of capillary was performed using microplasma copolymerization. • Monomer ratios were manipulated via liquid injection and helical mixing. • Films were studied in detail using standard characterization techniques. • The stability of the coating was observed by immersing the films in deionized water.

  6. Utilization of Mineral Wools as Alkali-Activated Material Precursor

    Directory of Open Access Journals (Sweden)

    Juho Yliniemi

    2016-04-01

    Full Text Available Mineral wools are the most common insulation materials in buildings worldwide. However, mineral wool waste is often considered unrecyclable because of its fibrous nature and low density. In this paper, rock wool (RW and glass wool (GW were studied as alkali-activated material precursors without any additional co-binders. Both mineral wools were pulverized by a vibratory disc mill in order to remove the fibrous nature of the material. The pulverized mineral wools were then alkali-activated with a sodium aluminate solution. Compressive strengths of up to 30.0 MPa and 48.7 MPa were measured for RW and GW, respectively, with high flexural strengths measured for both (20.1 MPa for RW and 13.2 MPa for GW. The resulting alkali-activated matrix was a composite-type in which partly-dissolved fibers were dispersed. In addition to the amorphous material, sodium aluminate silicate hydroxide hydrate and magnesium aluminum hydroxide carbonate phases were identified in the alkali-activated RW samples. The only crystalline phase in the GW samples was sodium aluminum silicate. The results of this study show that mineral wool is a very promising raw material for alkali activation.

  7. Sentinel-5 Precursor: Preparing the first Copernicus Atmospheric Mission

    Science.gov (United States)

    Nett, Herbert; McMullan, Kevin; Ingmann, Paul; Fehr, Thorsten

    2015-11-01

    Sentinel-5 Precursor (S-5P) will be the first of a series of atmospheric missions to be launched within the European Commission's Copernicus (former GMES) Programme. With a planned launch in 2016 and a nominal lifetime of 7 years S-5P is expected to provide continuity in the availability of global atmospheric data products between its predecessor missions SCIAMACHY (Envisat) and OMI (AURA) and the future Sentinel-4 and -5 series. The latter will comprise payload instruments on board the operational satellites MTG-S (S-4, geostationary component) and MetOp Second Generation (S-5, polar orbiting component), the first units of which will be launched in the 2020-2021 timeframe.The S-5P satellite will carry a single payload, TROPOMI (TROPOspheric Monitoring Instrument) which is jointly developed by The Netherlands and ESA. Covering spectral channels in the UV, visible, near- and short-wave infrared it will measure various key species including tropospheric/stratospheric ozone, NO2, SO2, CO, CH4, CH2O as well as cloud and aerosol parameters.

  8. Sentinel-5 Precursor: Global Monitoring of Atmospheric Trace Gases & Aerosols

    Science.gov (United States)

    Nett, Herbert; McMullan, Kevin; Ingmann, Paul

    2013-04-01

    ESA's Sentinel 5 Precursor (S5P) Mission will form part of the Space Component under the Global Monitoring for Environment and Security (GMES) initiative. It represents a preparatory project for the GMES atmospheric missions that comprise both a geo-stationary (Sentinel-4 / part of MTG-S payload) and a polar orbiting (Sentinel-5 / MetOp Second Generation) component. In view of the planned launch date of around 2020 for the first S-4 MTG-S and MetOp-SG spacecrafts, respectively, S5P (launch: mid 2015) shall minimize gaps in the availability of global atmospheric data products as provided by its predecessor missions SCIAMACHY (Envisat) and OMI (AURA). The satellite's single payload instrument, TROPOMI (TROPOspheric Monitoring Instrument), is jointly developed by The Netherlands and ESA. Covering spectral channels located in the UV, visible, near- and short-wave infrared it will measure various key species including stratospheric ozone, as well as NO2, SO2, CO, CH4, CH2O and aerosols, specifically in the lower Troposphere. The envisaged formation flying with NASA's Suomi NPP satellite will allow use of high spatial resolution imager data for enhanced cloud clearing of the observational data specifically in the short-wave infrared range. An outline of the Sentinel-5P mission objectives will be given. The status of development activities, covering Spacecraft and the Ground Segment will be presented.

  9. Accident sequence precursor analysis level 2/3 model development

    Energy Technology Data Exchange (ETDEWEB)

    Lui, C.H. [Nuclear Regulatory Commission, Washington, DC (United States); Galyean, W.J.; Brownson, D.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [and others

    1997-02-01

    The US Nuclear Regulatory Commission`s Accident Sequence Precursor (ASP) program currently uses simple Level 1 models to assess the conditional core damage probability for operational events occurring in commercial nuclear power plants (NPP). Since not all accident sequences leading to core damage will result in the same radiological consequences, it is necessary to develop simple Level 2/3 models that can be used to analyze the response of the NPP containment structure in the context of a core damage accident, estimate the magnitude of the resulting radioactive releases to the environment, and calculate the consequences associated with these releases. The simple Level 2/3 model development work was initiated in 1995, and several prototype models have been completed. Once developed, these simple Level 2/3 models are linked to the simple Level 1 models to provide risk perspectives for operational events. This paper describes the methods implemented for the development of these simple Level 2/3 ASP models, and the linkage process to the existing Level 1 models.

  10. Formation of titanosilicate precursors of an active adsorption phase

    Science.gov (United States)

    Kuznetsova, T. F.; Ivanets, A. I.; Katsoshvili, L. L.

    2017-04-01

    Micro-mesoporous titanosilicate precursors of the active absorption phase of a composite ceramic membrane are synthesized, and their textural and adsorption properties are investigated by means of low-temperature nitrogen adsorption/desorption. Low-temperature isotherms of nitrogen adsorption/desorption are analyzed using the BET, Langmuir, comparative t-plot, Barrett-Joyner-Halenda, and density functional theory methods. It is found that at high contents of silicon(IV) oxide, the resulting xerogels have surface areas of 656 and 890 m2/g according to the BET and Langmuir approaches, respectively, while the micropores' inner and outer surfaces are 453 and 466 m2/g, respectively, according to the t-plot. According to the DFT distributions, the mesopore diameters of a sample can be adjusted in the range of 3-9 nm. By analyzing the type of capillary condensation hysteresis in the adsorption/desorption isotherms, it is shown that the pores in the samples are very bottle-like, even though their shape may be different in reality. It is found that in samples with high contents of titanium(IV) oxide, the pore throats are blocked during adsorbate desorption, due to the percolation effect. It is assumed that the stabilization of particles of titanium(IV) oxide by amorphous layers of silica protects the texture of titanosilicate xerogels from full contraction and the coalescence of particles during heat treatment ranging from 393 to 923 K.

  11. Precursors of Executive Function in Infants With Sickle Cell Anemia

    Science.gov (United States)

    Hogan, Alexandra M.; Telfer, Paul T.; Kirkham, Fenella J.; de Haan, Michelle

    2013-01-01

    Executive dysfunction occurs in sickle cell anemia, but there are few early data. Infants with sickle cell anemia (n = 14) and controls (n = 14) performed the “A-not-B” and Object Retrieval search tasks, measuring precursors of executive function at 9 and 12 months. Significant group differences were not found. However, for the A-not-B task, 7 of 11 sickle cell anemia infants scored in the lower 2 performance categories at 9 months, but only 1 at 12 months (P = .024); controls obtained scores at 12 months that were statistically comparable to the scores they had already obtained at 9 months. On the Object Retrieval task, 9- and 12-month controls showed comparable scores, whereas infants with sickle cell anemia continued to improve (P = .027); at 9 months, those with lower hemoglobin oxygen saturation passed fewer trials (R s = 0.670, P = .024) and took longer to obtain the toy (R s = –0.664, P = .013). Subtle delays in acquiring developmental skills may underlie abnormal executive function in childhood. PMID:22859700

  12. Defining the cellular precursors to human breast cancer

    Science.gov (United States)

    Keller, Patricia J.; Arendt, Lisa M.; Skibinski, Adam; Logvinenko, Tanya; Klebba, Ina; Dong, Shumin; Smith, Avi E.; Prat, Aleix; Perou, Charles M.; Gilmore, Hannah; Schnitt, Stuart; Naber, Stephen P.; Garlick, Jonathan A.; Kuperwasser, Charlotte

    2012-01-01

    Human breast cancers are broadly classified based on their gene-expression profiles into luminal- and basal-type tumors. These two major tumor subtypes express markers corresponding to the major differentiation states of epithelial cells in the breast: luminal (EpCAM+) and basal/myoepithelial (CD10+). However, there are also rare types of breast cancers, such as metaplastic carcinomas, where tumor cells exhibit features of alternate cell types that no longer resemble breast epithelium. Until now, it has been difficult to identify the cell type(s) in the human breast that gives rise to these various forms of breast cancer. Here we report that transformation of EpCAM+ epithelial cells results in the formation of common forms of human breast cancer, including estrogen receptor-positive and estrogen receptor-negative tumors with luminal and basal-like characteristics, respectively, whereas transformation of CD10+ cells results in the development of rare metaplastic tumors reminiscent of the claudin-low subtype. We also demonstrate the existence of CD10+ breast cells with metaplastic traits that can give rise to skin and epidermal tissues. Furthermore, we show that the development of metaplastic breast cancer is attributable, in part, to the transformation of these metaplastic breast epithelial cells. These findings identify normal cellular precursors to human breast cancers and reveal the existence of a population of cells with epidermal progenitor activity within adult human breast tissues. PMID:21940501

  13. Are Nuclear Star Clusters the Precursors of Massive Black Holes?

    Directory of Open Access Journals (Sweden)

    Nadine Neumayer

    2012-01-01

    Full Text Available We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 106M⊙, if any. We also derive new upper limits for nuclear star cluster masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following. (1 The MBH-σ relation cannot flatten at low masses, but may steepen. (2 The MBH-Mbulge relation may well flatten in contrast. (3 The MBH-Sersic n relation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in the MBH-Sersic n relation seem to be dwarf elliptical galaxies. When plotting MBH versus MNC we find three different regimes: (a nuclear cluster dominated nuclei, (b a transition region, and (c black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratio MBH/MNC grows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.

  14. Genetic Alterations in Presumptive Precursor Lesions of Breast Carcinomas

    Directory of Open Access Journals (Sweden)

    Michaela Aubele

    2002-01-01

    Full Text Available The hypothetical multistep model of breast carcinogenesis suggests a transition from normal epithelium to invasive carcinoma via intraductal hyperplasia (without and with atypia and in situcarcinoma. These presumptive precursor lesions are currently defined by their histological features, and their prognosis is imprecisely estimated from indirect epidemiological evidence. Cytogenetic and molecular‐genetic analysis of these lesions give evidence for an accumulation of various genetic alterations during breast tumorigenesis. Using immuno‐histochemistry overexpression of the c‐erbB‐2 oncogene was found in ductal carcinoma in situ(DCIS, but not in atypical intraductal hyperplasia (AIDH and intraductal hyperplasia (IDH. An expression of mutant p53 tumor suppressor gene as well as expression of cyclin D1 was identified in DCIS. In IDH lesions loss of heterozygosity (LOH at various loci could be identified, and comparative genomic hybridization (CGH and fluorescence in situhybridization (FISH studies delivered evidence for DNA amplification on chromosomal region 20q13 in the early stage of IDH. However, little is currently known about genetic alterations in those premalignant lesions, and the chronology of genetic alterations and histopathological changes during carcinogenesis is mainly undiscovered. Figure 1 can be viewed in colour on http://www.esacp.org/acp/2002/24‐23/aubele.htm

  15. Precursor ion exclusion for enhanced identification of plasma biomarkers.

    Science.gov (United States)

    Wu, Wells W; Shen, Rong-Fong; Park, Sung-Soo; Martin, Bronwen; Maudsley, Stuart

    2012-06-01

    Our study aims to establish a plasma biomarker analysis workflow, with fewer fractionation steps, for enhanced identification of plasma biomarkers by precursor ion exclusion (PIE). Plasma samples were depleted for highly abundant proteins, then further fractionated by molecular weight (MW), before trypsinization for LTQ-Orbitrap mass analysis. Data-dependent acquisition (DDA) was used for baseline analysis. PIE involves the re-injection of samples with exclusion of the previously identified peptides. We compared analyses using multiple PIE iterations, compared to DDA, for plasma interrogation A higher percentage of unique plasma peptides was identified with PIE, compared to DDA. The first PIE iteration reveals an increase of 75-112% more peptides than the DDA method alone. PIE can interrogate complex plasma samples with the percentage of peptides identified successively increasing with even ≥4 iterations. The total number of peptides identified increases rapidly across the first three PIE iterations and then continues more slowly up to nine iterations. Iterative injections with PIE resulted in many more peptide identifications in plasma samples of varying degrees of complexity, compared to re-injections using similar DDA parameters. PIE methods may therefore expand our ability to recover plasma peptides for plasma biomarker discovery. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Liquid precursor films spreading on chemically patterned substrates

    Science.gov (United States)

    Checco, Antonio

    2008-03-01

    We study the spreading of nonvolatile liquid squalane on chemically patterned nanostripes by using non-contact Atomic Force Microscopy (NC-AFM). The substrates are octadecylthrichlorosilane(OTS)-coated silicon wafers chemically patterned on multiple length-scales using a combination of UV and AFM oxidative lithographies. This process allows us to locally convert the terminal methyl groups of the OTS surface (non-wettable) into carboxylic acid groups (wettable) without affecting considerably the substrate roughness (squalane spreads across this ``microfluidic network'' starting from the large lines eventually reaching the nanolines (50 to 500 nm-wide). NC-AFM is used to image the morphology of the liquid as it spreads across the nanolines. We find that the liquid thickness on the nanolines grows with time (up to ˜10 nm) according to a power-law with exponent ˜1. These preliminary results suggest that the spreading dynamics of laterally-confined liquids slightly differs, as expected, from the one of laterally homogeneous precursor films. We compare our findings to recent theoretical predictions of confined liquid flow and also discuss its relevance to nanofluidics.

  17. Vaporization of a mixed precursors in chemical vapor deposition for YBCO films

    Science.gov (United States)

    Zhou, Gang; Meng, Guangyao; Schneider, Roger L.; Sarma, Bimal K.; Levy, Moises

    1995-01-01

    Single phase YBa2Cu3O7-delta thin films with T(c) values around 90 K are readily obtained by using a single source chemical vapor deposition technique with a normal precursor mass transport. The quality of the films is controlled by adjusting the carrier gas flow rate and the precursor feed rate.

  18. Detecting the onset of bifurcations and their precursors from noisy data

    Energy Technology Data Exchange (ETDEWEB)

    Omberg, Larsson [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Royal Institute of Technology (KTH), Stockholm, (Sweden); Dolan, Kevin [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Neiman, Alexander [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States); Moss, Frank [Center for Neurodynamics, University of Missouri at St. Louis, St. Louis, Missouri 63121 (United States)

    2000-05-01

    We study the problem of the detection of noise-induced precursors of periodic motion instabilities in stochastic dynamical systems. In particular, we concentrate on the period-doubling bifurcation. We have developed a statistical method to detect the onset of bifurcations and their precursors based on the previously established topological recurrence technique. (c) 2000 The American Physical Society.

  19. Specificity of leaf mitochondrial and chloroplast processing systems for nuclear-encoded precursor proteins.

    Science.gov (United States)

    Whelan, J; Knorpp, C; Harmey, M A; Glaser, E

    1991-02-01

    The specificity of the mitochondrial and chloroplast processing enzymes for the nuclear-encoded precursor proteins was investigated. Mitochondrial precursor proteins of the Nicotiana plumbaginifolia and the Neurospora crassa beta subunits of F1-ATPase and the Neurospora Rieske FeS precursor protein were processed to the correct mature size by matrix extracts isolated from spinach leaves, yeast, rat liver and beef heart. The mitochondrial extracts failed to process chloroplast precursor proteins of the stromal small subunit of ribulose 1,5-bisphosphate carboxylase and the thylakoid 33 kDa protein of the oxygen-evolving complex. Both mitochondrial F1 beta precursors were specifically processed by a soluble stromal extract from chloroplasts. However, no processing of the Rieske FeS precursor protein was observed under the same conditions with the chloroplast extract. The cleavage of the mitochondrial F1 beta precursors by the chloroplast extract was shown to be sensitive to the metal chelators EDTA and ortho-phenanthroline. The cleavage site of the mitochondrial F1 beta precursor by the chloroplast soluble extract appears to be located at the N-terminus.

  20. Plasma glutamine is a minor precursor for the synthesis of citrulline: A multispecies study

    Science.gov (United States)

    Glutamine is considered the main precursor for citrulline synthesis in many species, including humans. The transfer of 15N from 2[15N]-glutamine to citrulline has been used as evidence for this precursor-product relationship. However, work in mice has shown that nitrogen and carbon tracers follow di...

  1. The theory of planned behavior: Precursors of marijuana use in early adolescence?

    NARCIS (Netherlands)

    Malmberg, M.; Overbeek, G.J.; Vermulst, A.A.; Monshouwer, K.; Vollebergh, W.A.M.; Engels, R.C.M.E.

    2012-01-01

    Background: Precursors of marijuana use in early adolescence are largely unknown because studies generally focus on marijuana use among older adolescents or adults. Methods: In this study, we examined precursors of marijuana use in a sample of 1023 Dutch early adolescents (aged 11-14 at Time 1) who

  2. Bulk and Surface Structures of Palladium-Modified Copper-Zinc Oxides ex Hydroxycarbonate Precursors

    NARCIS (Netherlands)

    López Granados, M.; Melián-Cabrera, I.; Fierro, J.L.G.

    2002-01-01

    (Pd)-Cu-Zn ex hydroxycarbonate precursors were prepared and characterized by several bulk and surface techniques. A palladium-free Cu-Zn precursor (CZ) was prepared by coprecipitation. Two Pd-Cu-Zn samples were prepared by coprecipitation (PCZ-CP) and sequential precipitation (PCZ-SP). It is shown

  3. Mechanistic modeling study on process optimization and precursor utilization with atmospheric spatial atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Zhang; He, Wenjie; Duan, Chenlong [State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Chen, Rong, E-mail: rongchen@mail.hust.edu.cn [State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Shan, Bin [State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

    2016-01-15

    Spatial atomic layer deposition (SALD) is a promising technology with the aim of combining the advantages of excellent uniformity and conformity of temporal atomic layer deposition (ALD), and an industrial scalable and continuous process. In this manuscript, an experimental and numerical combined model of atmospheric SALD system is presented. To establish the connection between the process parameters and the growth efficiency, a quantitative model on reactant isolation, throughput, and precursor utilization is performed based on the separation gas flow rate, carrier gas flow rate, and precursor mass fraction. The simulation results based on this model show an inverse relation between the precursor usage and the carrier gas flow rate. With the constant carrier gas flow, the relationship of precursor usage and precursor mass fraction follows monotonic function. The precursor concentration, regardless of gas velocity, is the determinant factor of the minimal residual time. The narrow gap between precursor injecting heads and the substrate surface in general SALD system leads to a low Péclet number. In this situation, the gas diffusion act as a leading role in the precursor transport in the small gap rather than the convection. Fluid kinetics from the numerical model is independent of the specific structure, which is instructive for the SALD geometry design as well as its process optimization.

  4. Precursors of ribosomal RNA in yeast nucleus : Biosynthesis and relation to cytoplasmic ribosomal RNA

    NARCIS (Netherlands)

    Sillevis Smitt, W.W.; Vlak, J.M.; Schiphof, R.; Rozijn, Th.H.

    In vivo methylated precursors of ribosomal RNA in yeast have been characterized on acrylamide gels. The initial ribosomal precursor in the yeast nucleus is a 37S RNA component, which is processed to a nuclear 28S RNA. Both the 37S and the 28S RNA components are important constituents of the yeast

  5. FT-IR and 29 Si-NMR for evaluating aluminium silicate precursors for geopolymers

    NARCIS (Netherlands)

    Valcke, S.L.A.; Pipilikaki, P.; Fischer, H.R.; Verkuijlen, M.H.W.; Eck, E.R.H.

    2014-01-01

    Geopolymers are systems of inorganic binders that can be used for sustainable, cementless concrete and are formed by alkali activation of an aluminium–silicate precursor (often secondary resources like fly ash or slag). The type of aluminium– silicate precursor and its potential variations within

  6. Effects of Peer Mediation on Preschoolers' Compliance and Compliance Precursors

    Science.gov (United States)

    Beaulieu, Lauren; Hanley, Gregory P.; Roberson, Aleasha A.

    2013-01-01

    We used a multiple baseline design across participants to evaluate the effects of teaching 4 typically developing preschoolers to attend to their names and to a group call (referred to as "precursors") on their compliance with typical classroom instructions. We then measured the extent to which the effects on both precursors and…

  7. Validation of Measures of Biosocial Precursors to Borderline Personality Disorder: Childhood Emotional Vulnerability and Environmental Invalidation

    Science.gov (United States)

    Sauer, Shannon E.; Baer, Ruth A.

    2010-01-01

    Linehan's biosocial theory suggests that borderline personality disorder (BPD) results from a transaction of two childhood precursors: emotional vulnerability and an invalidating environment. Until recently, few empirical studies have explored relationships between these theoretical precursors and symptoms of the disorder. Psychometrically sound…

  8. Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.X., E-mail: zexin.yu@utbm.fr [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Ma, Y.Z., E-mail: yangzhou.ma@outlook.com [School of Materials Science and Engineering, Anhui University of Technology, Ma’anshan 243002 (China); Zhao, Y.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France); Huang, J.B.; Wang, W.Z. [Key Lab of Safety Science of Pressurized System, Ministry of Education, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Moliere, M.; Liao, H.L. [Univ Bourgogne Franche Comte, CNRS, Lab ICB, UMR 6303, Site UTBM, F-90010 Belfort (France)

    2017-08-01

    Highlights: • C-axis preferential oriented grown ZnO films were firstly deposited via SPPS with different solutions. • ZnO films were hydrophobic due to cauliflower and honeycomb-like surface morphologies with high surface specific area. • Gas detecting performance of (002) plane oriented ZnO was predicted and compared by “first principle calculation method”. - Abstract: Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P{sub (002).} It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the “first principle calculation method” and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have

  9. Algunas aclaraciones acerca del conocimiento del singular.

    Directory of Open Access Journals (Sweden)

    Carlos Llano Cifuentes

    2013-11-01

    Full Text Available Llano tries to explain the main purpose of El Conocimiento del Singular, showing how the individuals about which the book is concerned are basically human individuals: people as decision makers.

  10. Impacto del manejo del ecosistema del pastizal en la fertilidad natural y sostenibilidad del suelo

    Directory of Open Access Journals (Sweden)

    A. Senra

    2009-01-01

    Full Text Available Sobre la base de resultados, principalmente de Cuba, el objetivo del presente trabajo fue estudiar el impacto del manejo del ecosistema del pastizal, en condiciones del trópico estacional -en sistemas de explotación bovina- para conocer sus efectos en la sostenibilidad y eficiencia del pastizal y el suelo. Se discute el efecto del manejo del pastizal en la compactación, y el escurrimiento e infiltración del agua, así como la erosión pluvial de los suelos. Se señalan los impactos positivos de la inclusión de los árboles multipropósito en los pastizales y sus efectos en disminuir las radiaciones solares y evaporación en el suelo, así como suavizar el ambiente. Se indican índices fundamentales para el control sistemático de la sostenibilidad y eficiencia en los sistemas de explotación bovina con base de pastos; se enfatiza el papel decisivo del hombre en garantizar adecuadas tecnologías de manejo y su ajuste a las condiciones de explotación. Se llega a conclusiones y recomendaciones que podrán ayudar a la recuperación, sostenibilidad y eficiencia de la ganadería en nuestras condiciones.

  11. Historia deldel = History of Padel

    OpenAIRE

    Sánchez-Alcaraz Martínez, Bernardino Javier

    2013-01-01

    El presente trabajo resume la historia del deporte deldel. Existen dos versiones sobre el origen deldel. La primera versión relaciona los antecedentes deldel con los de otros deportes de raqueta como el tenis o el bádminton, siendo su origen común el jeu de la paume francés. Posteriormente, surgen variantes en Estados Unidos como el Paddle Tennis y el Platform Tennis, siendo versiones reducidas del tenis, pero con elementos muy comunes al pádel actual. La segunda versión, aprobada po...

  12. SULL'ORIGINE DEL ROMBO DEL TUONO

    Directory of Open Access Journals (Sweden)

    g. zanotelli

    1951-06-01

    Full Text Available Si interpretano le cause fisiche di due fra le più singolari caratteristichedel rombo del tuono, e cioè la sua lunga persistenza ed iltimbro eminentemente ricco di suoni bassi. Per quanto altri autoriavessero in passato localizzato l'origine di questi fatti in svariate edoccasionali circostanze di ambiente, si è potuto dimostrare teoricamentenel presente lavoro come gli ammassi di goccioline di acqua checostituiscono le formazioni nuvolose esercitino una riflessione selettivasulle onde sonore incidenti: precisamente tale riflessione avviene inmisura apprezzabile solo per le componenti della perturbazione sonora,originata dallo scoppio del fulmine, di frequenza inferiore acerte due frequenze di taglio, proprie, l'ima del fenomeno di alternacondensazione ed evaporazione delle goccioline sotto l'azione delle variazionidi pressione sonora, e l'altra del parziale trascinamento dellegoccioline stesse nel moto dell'onda sonora per effetto della viscositàdell'aria. In base a questi risultati e tenuta anche presente la eventualitàdi più riflessioni successive si giustifica come, a causa dellabassa velocità del suono nell'atmosfera e della relativamente grandedistanza delle nubi, il rumore del tuono possa persistere a lungo; sipuò inoltre prevedere che il timbro sonoro debba farsi sempre piùcupo, via via che il rimbombo si prolunga.

  13. Novel precursors for the deposition of rare earth oxides; Neuartige Precursor zur Abscheidung von Selten-Erd-Oxiden

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, Mareike

    2010-02-22

    During this work rare earth solvates with nitrate and perchlorate anions have been investigated. All compounds have been structurally characterized and analyzed using thermal gravimetric analysis. The decomposition residues were analyzed using powder diffraction methods. Almost all compounds showed a characteristically intense exothermic decomposition step during the thermal decomposition, most likely caused by an intramolecular redox reaction between the nitrate or perchlorate anion respectively and the organic solvent molecules. The nitrates RE(NO{sub 3}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 2} (RE = Sm, Eu) were isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. The known compound group of dimethoxyethane solvates was then expanded with RE(NO{sub 3}){sub 3}(O{sub 2}C{sub 4}H{sub 10}) (RE = La, Sm, Eu). Considering the possible use as precursor material the already described neodymium compound is also discussed. The thermal decomposition of these compounds yields the respective cubic rare earth oxide and shows the typical intense exothermic decomposition reaction. A variety of different precursor system based on nitrate solvates for the deposition of rare earth oxide layers on a silicon surface was developed and investigated in collaboration with the group of Prof. Dr. Al-Shamery (Univ. Oldenburg). Ultra thin films on a H-Si(111) surface were obtained via the deposition of the precursor, which was dissolved in organic solvents. An oxide layer was detected after the heating of the sample. The film thickness was measured as < 10 nm, whereas the thickness of the film was controlled by the concentration of the precursor solution. Sm(ClO{sub 4}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 3} was isolated and characterized for the first time as the intermediate of the dehydration reaction with trimethyl orthoformate. Eu(ClO{sub 4}){sub 3}(CH(OCH{sub 3}){sub 3}){sub 2}(MeOH){sub 2} was obtained without

  14. Advanced accident sequence precursor analysis level 1 models

    Energy Technology Data Exchange (ETDEWEB)

    Sattison, M.B.; Thatcher, T.A.; Knudsen, J.K.; Schroeder, J.A.; Siu, N.O. [Idaho National Engineering Lab., Idaho National Lab., Idaho Falls, ID (United States)

    1996-03-01

    INEL has been involved in the development of plant-specific Accident Sequence Precursor (ASP) models for the past two years. These models were developed for use with the SAPHIRE suite of PRA computer codes. They contained event tree/linked fault tree Level 1 risk models for the following initiating events: general transient, loss-of-offsite-power, steam generator tube rupture, small loss-of-coolant-accident, and anticipated transient without scram. Early in 1995 the ASP models were revised based on review comments from the NRC and an independent peer review. These models were released as Revision 1. The Office of Nuclear Regulatory Research has sponsored several projects at the INEL this fiscal year to further enhance the capabilities of the ASP models. Revision 2 models incorporates more detailed plant information into the models concerning plant response to station blackout conditions, information on battery life, and other unique features gleaned from an Office of Nuclear Reactor Regulation quick review of the Individual Plant Examination submittals. These models are currently being delivered to the NRC as they are completed. A related project is a feasibility study and model development of low power/shutdown (LP/SD) and external event extensions to the ASP models. This project will establish criteria for selection of LP/SD and external initiator operational events for analysis within the ASP program. Prototype models for each pertinent initiating event (loss of shutdown cooling, loss of inventory control, fire, flood, seismic, etc.) will be developed. A third project concerns development of enhancements to SAPHIRE. In relation to the ASP program, a new SAPHIRE module, GEM, was developed as a specific user interface for performing ASP evaluations. This module greatly simplifies the analysis process for determining the conditional core damage probability for a given combination of initiating events and equipment failures or degradations.

  15. Distinct amyloid precursor protein processing machineries of the olfactory system.

    Science.gov (United States)

    Kim, Jae Yeon; Rasheed, Ameer; Yoo, Seung-Jun; Kim, So Yeun; Cho, Bongki; Son, Gowoon; Yu, Seong-Woon; Chang, Keun-A; Suh, Yoo-Hun; Moon, Cheil

    2018-01-01

    Processing of amyloid precursor protein (APP) occurs through sequential cleavages first by β-secretase and then by the γ-secretase complex. However, abnormal processing of APP leads to excessive production of β-amyloid (Aβ) in the central nervous system (CNS), an event which is regarded as a primary cause of Alzheimer's disease (AD). In particular, gene mutations of the γ-secretase complex-which contains presenilin 1 or 2 as the catalytic core-could trigger marked Aβ accumulation. Olfactory dysfunction usually occurs before the onset of typical AD-related symptoms (eg, memory loss or muscle retardation), suggesting that the olfactory system may be one of the most vulnerable regions to AD. To date however, little is known about why the olfactory system is affected so early by AD prior to other regions. Thus, we examined the distribution of secretases and levels of APP processing in the olfactory system under either healthy or pathological conditions. Here, we show that the olfactory system has distinct APP processing machineries. In particular, we identified higher expressions levels and activity of γ-secretase in the olfactory epithelium (OE) than other regions of the brain. Moreover, APP c-terminal fragments (CTF) are markedly detected. During AD progression, we note increased expression of presenilin2 of γ-secretases in the OE, not in the OB, and show that neurotoxic Aβ*56 accumulates more quickly in the OE. Taken together, these results suggest that the olfactory system has distinct APP processing machineries under healthy and pathological conditions. This finding may provide a crucial understanding of the unique APP-processing mechanisms in the olfactory system, and further highlights the correlation between olfactory deficits and AD symptoms. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Is Monoglucosyldiacylglycerol a Precursor to Monogalactosyldiacylglycerol in All Cyanobacteria?

    Science.gov (United States)

    Sato, Naoki

    2015-10-01

    Monogalactosyldiacylglycerol (MGDG) is ubiquitous in the photosynthetic membranes of cyanobacteria and chloroplasts. It is synthesized by galactosylation of diacylglycerol (DAG) in the chloroplasts, whereas it is produced by epimerization of monoglucosyldiacylglycerol (GlcDG) in at least several cyanobacteria that have been analyzed such as Synechocystis sp. PCC 6803. A previous study, however, showed that the mgdE gene encoding the epimerase is absent in some cyanobacteria such as Gloeobacter violaceus, Thermosynechococcus elongatus and Acaryochloris marina. In addition, the N-terminal 'fatty acid hydroxylase' domain is lacking in the MgdE protein of Prochlorococcus marinus. These problems may cast doubt upon the general (or exclusive) role of MgdE in the epimerization of GlcDG to MGDG in cyanobacteria. In addition, GlcDG is usually present at a very low level, and the structural determination of endogenous GlcDG has not been accomplished with cyanobacterial samples. In this study, I determined the structure of GlcDG from Anabaena variabilis by (1)H- and (13)C-nuclear magnetic resonance (NMR) spectroscopy. I then showed that G. violaceus, T. elongatus, A. marina and P. marinus contain GlcDG. In all cases, GlcDG consisted of fewer unsaturated molecular species than MGDG, providing further evidence that GlcDG is a precursor to MGDG. The conversion of GlcDG to MGDG was also demonstrated by radiolabeling and chase experiments in G. violaceus and P. marinus. These results demonstrate that all the analyzed cyanobacteria contain GlcDG, which is converted to MGDG, and suggest that an alternative epimerase is required for MGDG synthesis in these cyanobacteria. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. The ether lipid precursor hexadecylglycerol protects against Shiga toxins.

    Science.gov (United States)

    Bergan, Jonas; Skotland, Tore; Lingelem, Anne Berit Dyve; Simm, Roger; Spilsberg, Bjørn; Lindbäck, Toril; Sylvänne, Tuulia; Simolin, Helena; Ekroos, Kim; Sandvig, Kirsten

    2014-11-01

    Shiga toxin-producing Escherichia coli bacteria cause hemorrhagic colitis and hemolytic uremic syndrome in humans. Currently, only supportive treatment is available for diagnosed patients. We show here that 24-h pretreatment with an ether lipid precursor, the alkylglycerol sn-1-O-hexadecylglycerol (HG), protects HEp-2 cells against Shiga toxin and Shiga toxin 2. Also the endothelial cell lines HMEC-1 and HBMEC are protected against Shiga toxins after HG pretreatment. In contrast, the corresponding acylglycerol, DL-α-palmitin, has no effect on Shiga toxicity. Although HG treatment provides a strong protection (~30 times higher IC₅₀) against Shiga toxin, only a moderate reduction in toxin binding was observed, suggesting that retrograde transport of the toxin from the plasma membrane to the cytosol is perturbed. Furthermore, endocytosis of Shiga toxin and retrograde sorting from endosomes to the Golgi apparatus remain intact, but transport from the Golgi to the endoplasmic reticulum is inhibited by HG treatment. As previously described, HG reduces the total level of all quantified glycosphingolipids to 50-70% of control, including the Shiga toxin receptor globotriaosylceramide (Gb3), in HEp-2 cells. In accordance with this, we find that interfering with Gb3 biosynthesis by siRNA-mediated knockdown of Gb3 synthase for 24 h causes a similar cytotoxic protection and only a moderate reduction in toxin binding (to 70% of control cells). Alkylglycerols, including HG, have been administered to humans for investigation of therapeutic roles in disorders where ether lipid biosynthesis is deficient, as well as in cancer therapy. Further studies may reveal if HG can also have a therapeutic potential in Shiga toxin-producing E. coli infections.

  18. Analysis of peripheral amyloid precursor protein in Angelman Syndrome.

    Science.gov (United States)

    Erickson, Craig A; Wink, Logan K; Baindu, Bayon; Ray, Balmiki; Schaefer, Tori L; Pedapati, Ernest V; Lahiri, Debomoy K

    2016-09-01

    Angelman Syndrome is a rare neurodevelopmental disorder associated with significant developmental and communication delays, high risk for epilepsy, motor dysfunction, and a characteristic behavioral profile. While Angelman Syndrome is known to be associated with the loss of maternal expression of the ubiquitin-protein ligase E3A gene, the molecular sequelae of this loss remain to be fully understood. Amyloid precursor protein (APP) is involved in neuronal development and APP dysregulation has been implicated in the pathophysiology of other developmental disorders including fragile X syndrome and idiopathic autism. APP dysregulation has been noted in preclinical model of chromosome 15q13 duplication, a disorder whose genetic abnormality results in duplication of the region that is epigenetically silenced in Angelman Syndrome. In this duplication model, APP levels have been shown to be significantly reduced leading to the hypothesis that enhanced ubiquitin-protein ligase E3A expression may be associated with this phenomena. We tested the hypothesis that ubiquitin-protein ligase E3A regulates APP protein levels by comparing peripheral APP and APP derivative levels in humans with Angelman Syndrome to those with neurotypical development. We report that APP total, APP alpha (sAPPα) and A Beta 40 and 42 are elevated in the plasma of humans with Angelman Syndrome compared to neurotypical matched human samples. Additionally, we found that elevations in APP total and sAPPα correlated positively with peripheral brain derived neurotrophic factor levels previously reported in this same patient cohort. Our pilot report on APP protein levels in Angelman Syndrome warrants additional exploration and may provide a molecular target of treatment for the disorder. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  19. Kininogens: More than cysteine protease inhibitors and kinin precursors.

    Science.gov (United States)

    Lalmanach, Gilles; Naudin, Clément; Lecaille, Fabien; Fritz, Hans

    2010-11-01

    Two kininogens are found in mammalian sera: HK (high molecular weight kininogen) and LK (low molecular weight kininogen) with the exception of the rat which encompasses a third kininogen, T-Kininogen (TK). Kininogens are multifunctional glycosylated molecules related to cystatins (clan IH, family I25). They harbor three cystatin domains but only two of them are tight-binding inhibitors of cysteine cathepsins. HK and LK, but not TK, are precursors of potent peptide hormones, the kinins, which are released proteolytically by tissue and plasma kallikreins. Besides these classical features novel functions of kininogens have been recently discovered; they are described in the second part of this review. HKa, which corresponds to the kinin-free two-chain HK and its isolated domain D5 (kininostatin), possesses angiostatic and pro-apoptotic properties, inhibits the proliferation of endothelial cells and participates in the regulation of angiogenesis. Moreover, some HK-derived peptides display potent and broad-spectrum microbicidal properties against both Gram-positive and Gram-negative bacteria, and thus may offer a promising alternative to conventional antibiotic therapy. Of seminal interest, a kininogen-derived peptide inhibits activation of the contact phase system of coagulation and protects mice with invasive Streptococcus pyogenes infection from pulmonary lesions. On the other hand, TK is a biomarker of aging at the end of lifespan of elderly rats. However, although TK has been initially identified as an acute phase reactant, and earlier known as alpha-l-acute phase globulin, the increase of TK in liver and plasma is not known to relate to any inflammatory event during the senescence process. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  20. Precursors to melanoma and their mimics: nevi of special sites.

    Science.gov (United States)

    Elder, David E

    2006-02-01

    Melanocytic nevi, which are benign tumors of melanocytes, may have occasional cosmetic significance but, for the most part, they are important only in relation to melanoma. Nevi are the most important simulants of melanoma, both clinically and histologically, and can usually be reliably distinguished from melanomas using published criteria. Some lesions are characterized by greater degrees of atypia and may be more difficult to diagnose. Dysplastic nevi are among the most important simulants of melanoma. Nevi may also be important as potential precursors of melanoma; however, most nevi are stable and will not progress to malignancy. Nevi are vastly more common than melanomas and the rate of progression of individual lesions is very low. Therefore, nevi are not as a rule managed by wholesale excision to prevent melanoma. Nevi are also important as risk markers, identifying individuals at greater risk of developing melanoma in the future. Dysplastic nevi and, to a lesser extent, common acquired and congenital nevi are among the most important melanoma risk markers. Nevi of special sites have been identified as nevi that may show atypical features suggestive of a dysplastic nevus or of a melanoma. However, they are not risk markers and they are not malignancies. Nevi of genital skin, acral skin, and flexural skin are among the most important 'nevi of special sites'. It is important, in considering the differential diagnosis of a lesion in a special site, to avoid overcalling such a lesion as a melanoma or a dysplastic nevus because this could lead to excessive treatment. Conversely, it is important to avoid undercalling a lesion that is a dysplastic nevus or a melanoma as a nevus of special sites, because in this circumstance a patient could lose the opportunity either for surveillance to recognize a developing melanoma at an early, curable stage, or for definitive treatment of an established malignancy. In this monograph, dysplastic nevi and nevi of special sites are

  1. PIE DESCALZO DEL INDIGENA DEL AMAZONAS

    Directory of Open Access Journals (Sweden)

    Valentín Malagón

    1985-12-01

    Full Text Available

    Dentro del trabajo que se está llevando a cabo en el servicio de ortopedia el Hospital Infantil de Bogotá, sobre la "Evolución de la postura del niño colombiano", trabajo iniciado hace ya más de cuatro años y algunas de cuyas características han sido descritas en comunicaciones anteriores, se creyó muy pertinente conocer ciertos detalles relacionados con la estructura y función del pie descalzo, lo cual permitiría hacer una serie de comparaciones entre éste y el pie del colombiano calzado, considerado como "normal" en la presente época. Hasta ahora se han examinado 4.013 individuos normales en el resto de Colombia. Por muchas razones se escogió a laAmazonía Colombiana, y dentro de ésta la zona de Leticia, como centro de este estudio.

    Se seleccionaron 294 historias de otros tantos nativos del Amazonas que tuvieron como hecho fundamental y común, el no haberse calzado nunca: correspondían a 154 hombres y 140 mujeres. Sus edades fluctuaron entre un mes de vida y 60 años de edad. Los grupos de edades se distribuyeron así: 136 menores de 10 años; 96 entre 11 y 20 años; 39 entre 21 y 30 años; 11 entre 31 y 40 años y 12 mayores de 41 años. El grupo estudiado procedía de 4 conglomerados indígenas: Arara: 41, Kilómetro 6:32, San Sebastián: 37 y Nazaret 84. (Figura 1. Se tomó el peso y la talla de los indígenas, así como medidas de la longitud de los pies; su anchura, la altura del dedo gordo, del quinto dedo y del empeine; el perímetro del antepie y del postpie; se estudió el arco longitudinal, la torsión tibial, el ángulo fémorotibial y los movimientos de rotación de la cadera. Se tomaron huellas plantares y en 50 de estos individuos, se realizaron radiografías de los pies, con y sin apoyo...

  2. Lu2O3-SiO2-ZrO2 Coatings for Environmental Barrier Application by Solution Precursor Plasma Spraying and Influence of Precursor Chemistry

    Science.gov (United States)

    Darthout, Émilien; Quet, Aurélie; Braidy, Nadi; Gitzhofer, François

    2014-02-01

    As environmental barrier coatings are subjected to thermal stress in gas turbine engines, the introduction of a secondary phase as zircon (ZrSiO4) is likely to increase the stress resistance of Lu2Si2O7 coatings generated by induction plasma spraying using liquid precursors. In a first step, precursor chemistry effect is investigated by the synthesis of ZrO2-SiO2 nanopowders by induction plasma nanopowder synthesis technique. Tetraethyl orthosilicate (TEOS) as silicon precursor and zirconium oxynitrate and zirconium ethoxide as zirconium precursors are mixed in ethanol and produce a mixture of tetragonal zirconia and amorphous silica nanoparticles. The use of zirconium ethoxide precursor results in zirconia particles with diameter below 50 nm because of exothermic thermal decomposition of the ethoxide and its high boiling point with respect to solvent, while larger particles are formed when zirconium oxynitrate is employed. The formation temperature of zircon from zirconia and silica oxides is found at 1425 °C. Second, coatings are synthesized in Lu2O3-ZrO2-SiO2 system. After heat treatment, the doping effect of lutetium on zirconia grains totally inhibits the zircon formation. Dense coatings are obtained with the use of zirconium ethoxide because denser particles with a homogeneous diameter distribution constitute the coating.

  3. Correlation of precursor and product ions in single-stage high resolution mass spectrometry. A tool for detecting diagnostic ions and improving the precursor elemental composition elucidation.

    Science.gov (United States)

    Borràs, S; Kaufmann, A; Companyó, R

    2013-04-15

    Monitoring of common diagnostic fragments is essential for recognizing molecules which are members of a particular compound class. Up to now, unit resolving tandem quadrupole mass spectrometers, operating in the precursor ion scan mode, have been typically used to perform such analysis. By means of high-resolution mass spectrometry (HRMS) a much more sensitive and selective detection can be achieved. However, using a single-stage HRMS instrument, there is no unequivocal link to the corresponding precursor ion, since such instrumentation does not permit a previous precursor selection. Thus, to address this limitation, an in silico approach to locate precursor ions, based on diagnostic fragments, was developed. Implemented as an Excel macro, the algorithm rapidly assembles and surveys exact mass data to provide a list of feasible precursor candidates according to the correlation of the chromatographic peak shape profile and other additional filtering criteria (e.g. neutral losses and isotopes). The macro was tested with two families of veterinary drugs, sulfonamides and penicillins, which are known to yield diagnostic product ions when fragmented. Data sets obtained from different food matrices (fish and liver), both at high and low concentration of the target compounds, were investigated in order to evaluate the capabilities and limitations of the reported approach. Finally, other possible applications of this technique, such as the elucidation of elemental compositions based on product ions and corresponding neutral losses, were also presented and discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Teleopio del Pueblo

    Directory of Open Access Journals (Sweden)

    Paul Little

    2015-01-01

    Full Text Available Temas trascendentes de este número son Historia del Nuevo Periodismo, Derecho Social a la información y La televisión: Teleopio del pueblo. Se agregan otros como la investigación en el trabajo popular, LA mujer rural , El audiovisual en el Ecuador y Cambios en la comunicación a raíz del NOMIC.

  5. Psicodrama del duelo.

    OpenAIRE

    José Antonio Espina Barrio; Marisol Filgueira Bouza

    1997-01-01

    La pérdida de rituales agrava y alarga la reacción del duelo. Se define el Psicodrama Antropológico y su intervención en el proceso del duelo. El Psicodrama Focal del Duelo es una psicoterapia breve centrada en el proceso de Duelo. Se comentan varios casos y resultados. Se concluye con un programa sencillo para el duelo en Atención Primaria.

  6. Fractura triple del complejo suspensorio del hombro

    Directory of Open Access Journals (Sweden)

    Eraclio Delgado Rifá

    2015-06-01

    Full Text Available El complejo suspensorio del hombro es una estructura sumamente importante, compuesta por un anillo de huesos y tejidos blandos. Las lesiones aisladas de este complejo anatómico son frecuentes y no afectan su estabilidad. La interrupción doble conduce a la inestabilidad de esta estructura y usualmente requiere tratamiento quirúrgico. La triple interrupción, por su parte, es sumamente rara y es encontrada en casos de trauma de alta energía a menudo en asociación con otras lesiones. Se presenta una triple lesión del complejo suspensorio del hombro en un paciente de 46 años de edad, con una fractura de la glenoides, del acromion tipo III de Kuhn y de la coracoides tipo II de Ogawa. En este caso, la fractura del acromion fue tratada con fijación percutánea con alambres de Kirschner, por tener asociado lesiones de partes blandas que contraindicaron la reducción abierta. La fractura de la glenoides y de la apófisis coracoides fueron tratadas conservadoramente. Después de 6 meses de evolución, el paciente tuvo un resultado funcional aceptable, con una abducción de 90 grados, los 30 grados de rotación externa y 70 de rotación interna, además asintomático y consolidación de todas las fracturas. A pesar de ser catalogada de una lesión grave del cinturón escapular y estar asociada a otras lesiones se obtuvo un resultado satisfactorio al final del tratamiento.

  7. Concepto del Derecho Mercantil

    OpenAIRE

    Morelli C., Francisco

    2014-01-01

    No existe nada más difícil en el campo del Derecho Mercantil que pretender dar un concepto orgánico del mismo. La razón fundamental de esta imposibilidad  estriba precisamente en la falta de concordancia entre el derecho mercantil y el derecho de comercio. Una definición que considera el derecho mercantil como la parte del derecho privado encargada de regular las relaciones que se derivan del comercio, como lo hacen todas las definiciones clásicas,  pecaría de un doble defecto que la harían i...

  8. Associations between musical abilities and precursors of reading in preschool aged children

    Science.gov (United States)

    Degé, Franziska; Kubicek, Claudia; Schwarzer, Gudrun

    2015-01-01

    The association between music and language, in particular, the overlap in their processing results in the possibility to use one domain for the enhancement of the other. Especially in the preschool years music may be a valuable tool to train language abilities (e.g., precursors of reading). Therefore, detailed knowledge about associations between musical abilities and precursors of reading can be of great use for designing future music intervention studies that target language-related abilities. Hence, the present study investigated the association between music perception as well as music production and precursors of reading. Thereby, not only phonological awareness, the mostly studied precursor of reading, was investigated, but also other precursors were examined. We assessed musical abilities (production and perception) and precursors of reading (phonological awareness, working memory, and rapid retrieval from long-term memory) in 55 preschoolers (27 boys). Fluid intelligence was measured and controlled in the analyses. Results showed that phonological awareness, working memory, and rapid retrieval from long-term memory were related to music perception as well as to music production. Our data suggest that several precursors of reading were associated with music perception as well as music production. PMID:26347687

  9. Marine bacterial transparent exopolymer particles (TEP) and TEP precursors: Characterization and RO fouling potential

    KAUST Repository

    Li, Sheng

    2015-10-31

    This paper investigated the characteristics and membrane fouling potential of bacterial transparent exopolymer particles (TEP)/TEP precursors released from two marine bacteria, Pseudidiomarina homiensis (P. homiensis) and Pseudoalteromonas atlantica (P. atlantica), isolated from the Red Sea. Results showed that both bacteria grew at the similar rate, but the production of TEP/TEP precursors from P. atlantica was higher than that from P. homiensis. During the 168. h of incubation time, production rates of TEP/TEP precursors from P. atlantica and P. homiensis were 0.30 and 0.08 xanthan gum eq. mg/L-h, respectively. Isolated bacterial TEP precursors were mainly biopolymer, and P. atlantica produced a significantly higher concentration of biopolymer than that produced by P. homiensis. TEP/TEP precursors from both marine bacteria possessed protein-like material and were very similar in composition to previously reported foulants isolated from a fouled reverse osmosis (RO) membrane. Bacterial TEP/TEP precursors mostly consisted of aliphatic hydrocarbon from amino acids and amide group carbon of proteins (around 55%). Bacterial TEP precursors caused obvious fouling on RO membranes, which may create an ideal environment for bacteria attachment and promote to biofouling.

  10. Nicotinamide Riboside Is a Major NAD+ Precursor Vitamin in Cow Milk.

    Science.gov (United States)

    Trammell, Samuel Aj; Yu, Liping; Redpath, Philip; Migaud, Marie E; Brenner, Charles

    2016-05-01

    Nicotinamide riboside (NR) is a recently discovered NAD(+) precursor vitamin with a unique biosynthetic pathway. Although the presence of NR in cow milk has been known for more than a decade, the concentration of NR with respect to the other NAD(+) precursors was unknown. We aimed to determine NAD(+) precursor vitamin concentration in raw samples of milk from individual cows and from commercially available cow milk. LC tandem mass spectrometry and isotope dilution technologies were used to quantify NAD(+) precursor vitamin concentration and to measure NR stability in raw and commercial milk. Nuclear magnetic resonance (NMR) spectroscopy was used to test for NR binding to substances in milk. Cow milk typically contained ∼12 μmol NAD(+) precursor vitamins/L, of which 60% was present as nicotinamide and 40% was present as NR. Nicotinic acid and other NAD(+) metabolites were below the limits of detection. Milk from samples testing positive for Staphylococcus aureus contained lower concentrations of NR (Spearman ρ = -0.58, P = 0.014), and NR was degraded by S. aureus Conventional milk contained more NR than milk sold as organic. Nonetheless, NR was stable in organic milk and exhibited an NMR spectrum consistent with association with a protein fraction in skim milk. NR is a major NAD(+) precursor vitamin in cow milk. Control of S. aureus may be important to preserve the NAD(+) precursor vitamin concentration of milk. © 2016 American Society for Nutrition.

  11. Associations between musical abilities and precursors of reading in preschool aged children.

    Science.gov (United States)

    Degé, Franziska; Kubicek, Claudia; Schwarzer, Gudrun

    2015-01-01

    The association between music and language, in particular, the overlap in their processing results in the possibility to use one domain for the enhancement of the other. Especially in the preschool years music may be a valuable tool to train language abilities (e.g., precursors of reading). Therefore, detailed knowledge about associations between musical abilities and precursors of reading can be of great use for designing future music intervention studies that target language-related abilities. Hence, the present study investigated the association between music perception as well as music production and precursors of reading. Thereby, not only phonological awareness, the mostly studied precursor of reading, was investigated, but also other precursors were examined. We assessed musical abilities (production and perception) and precursors of reading (phonological awareness, working memory, and rapid retrieval from long-term memory) in 55 preschoolers (27 boys). Fluid intelligence was measured and controlled in the analyses. Results showed that phonological awareness, working memory, and rapid retrieval from long-term memory were related to music perception as well as to music production. Our data suggest that several precursors of reading were associated with music perception as well as music production.

  12. Precursors to potential severe core damage accidents: 1994, a status report. Volume 22: Appendix I

    Energy Technology Data Exchange (ETDEWEB)

    Belles, R.J.; Cletcher, J.W.; Copinger, D.A.; Vanden Heuvel, L.N. [Oak Ridge National Lab., TN (United States); Dolan, B.W.; Minarick, J.W. [Oak Ridge National Lab., TN (United States)]|[Science Applications International Corp., Oak Ridge, TN (United States)

    1995-12-01

    Nine operational events that affected eleven commercial light-water reactors (LWRs) during 1994 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 {times} 10{sup {minus}6}. These events were identified by computer-screening the 1994 licensee event reports from commercial LWRs to identify those that could be potential precursors. Candidate precursors were then selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters and regional offices to ensure that the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969--1981 and 1984--1993 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for events. This document is bound in two volumes: Vol. 21 contains the main report and Appendices A--H; Vol. 22 contains Appendix 1.

  13. Precursors to potential severe core damage accidents: 1997 -- A status report. Volume 26

    Energy Technology Data Exchange (ETDEWEB)

    Belles, R.J.; Cletcher, J.W.; Copinger, D.A.; Muhlheim, M.D. [Oak Ridge National Lab., TN (United States); Dolan, B.W.; Minarick, J.W. [Science Applications International Corp., Oak Ridge, TN (United States)

    1998-11-01

    This report describes the five operational events in 1997 that affected five commercial light-water reactors (LWRs) and that are considered to be precursors to potential severe core damage accidents. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 {times} 10{sup {minus}6}. These events were identified by first computer-screening the 1997 licensee event reports from commercial LWRs to identify those events that could be precursors. Candidate precursors were selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters to ensure that the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969--1996 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for the events.

  14. Precursors to potential severe core damage accidents: 1995 A status report

    Energy Technology Data Exchange (ETDEWEB)

    Belles, R.J.; Cletcher, J.W.; Copinger, D.A. [and others

    1997-04-01

    Ten operational events that affected 10 commercial light-water reactors during 1995 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 x 10{sup {minus}6}. These events were identified by first computer-screening the 1995 licensee event reports from commercial light-water reactors to identify those events that could potentially be precursors. Candidate precursors were selected and evaluated in a process similar to that used in previous assessments. Selected events underwent engineering evaluation that identified, analyzed, and documented the precursors. Other events designated by the Nuclear Regulatory Commission (NRC) also underwent a similar evaluation. Finally, documented precursors were submitted for review by licensees and NRC headquarters and regional offices to ensure the plant design and its response to the precursor were correctly characterized. This study is a continuation of earlier work, which evaluated 1969-1981 and 1984-1994 events. The report discusses the general rationale for this study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for the events.

  15. Associations between musical abilities and precursors of reading in preschool aged children

    Directory of Open Access Journals (Sweden)

    Franziska eDegé

    2015-08-01

    Full Text Available The association between music and language, in particular, the overlap in their processing results in the possibility to use one domain for the enhancement of the other. Especially in the preschool years music may be a valuable tool to train language abilities (e.g., precursors of reading. Therefore, detailed knowledge about associations between musical abilities and precursors of reading can be of great use for designing future music intervention studies that target language-related abilities. Hence, the present study investigated the association between music perception as well as music production and precursors of reading. Thereby, not only phonological awareness, the mostly studied precursor of reading, was investigated, but also other precursors were examined. We assessed musical abilities (production and perception and precursors of reading (phonological awareness, working memory, and rapid retrieval from long-term memory in 55 preschoolers (27 boys. Fluid intelligence was measured and controlled in the analyses. Results showed that phonological awareness, working memory, and rapid retrieval from long-term memory were related to music perception as well as to music production. Our data suggest that several precursors of reading were associated with music perception as well as music production.

  16. Biochemical removal of HAP precursors from coal. Quarterly technical report, October 1, 1996--December 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.J.

    1997-01-01

    This fifth quarterly report covers the period of October through December of 1996. Results are presented of pyrite and HAP precursor removal from Kentucky No. 9 coal in shake flasks and from Indiana No. 5 coal in columns. With Kentucky coal, rates of pyrite oxidation were about 6% per day, and significant As, Co, Cd, Mn, and Ni were removed from the coal. These same five HAP precursors also were significantly removed from Indiana No. 5 coal. Additionally, test results are presented of pyrite and HAP precursor removal from Indiana No. 5 and Pittsburgh No. 8 coal using high initial concentrations of ferric ions. These tests showed faster depyritization of coal than in previous tests done with low initial ferric ion concentrations. In addition, faster and more extensive removal of Cd, Co, Mn, and Ni from Indiana No. 5 coal occurred under high ferric conditions. High solution ferric ion concentration are expected in any biodepyritization process due to progressive biooxidation of pyrite to ferric sulfate. Ferric ions are probably the primary oxidant of pyrite and many of the HAP precursors in coal. Analysis of HAP precursors in Stockton Coal, used by PETC in HAP precursor combustion-mass balance test, was done and compared to PETC analytical data. The INEL slurry column reactor was operated in several shake down runs to prepare for complete HAP precursor removal-mass balance tests. Good separation of coal from ash-forming minerals was observed in these tests.

  17. Mutagenesis of nisin's leader peptide proline strongly modulates export of precursor nisin.

    Science.gov (United States)

    Plat, Annechien; Kuipers, Anneke; Crabb, Joe; Rink, Rick; Moll, Gert N

    2017-03-01

    The lantibiotic nisin is produced by Lactococcus lactis as a precursor peptide comprising a 23 amino acid leader peptide and a 34 amino acid post-translationally modifiable core peptide. We previously demonstrated that the conserved FNLD part of the leader is essential for intracellular enzyme-catalyzed introduction of lanthionines in the core peptide and also for transporter-mediated export, whereas other positions are subject to large mutational freedom. We here demonstrate that, in the absence of the extracellular leader peptidase, NisP, export of precursor nisin via the modification and transporter enzymes, NisBTC, is strongly affected by multiple substitutions of the leader residue at position -2, but not by substitution of positions in the vicinity of this site. Export levels of precursor nisin increased by more than 70% for position -2 mutants Asp, Thr, Ser, Trp, Lys, Val and decreased more than 70% for Cys, His, Met. In a strain with leader peptidase, the Pro-2Lys and Pro-2Asp precursor nisins were less efficiently cleaved by NisP than wild type precursor nisin. Taken together, the wild type precursor nisin with a proline at position -2 allows balanced export and cleavage efficiencies by precursor nisin's transporter and leader peptidase.

  18. An optimized In–CuGa metallic precursors for chalcopyrite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jun-feng, E-mail: junfeng.han@cnrs-imn.fr [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Department of Physics, Peking University, Beijing 100871 (China); Liao, Cheng [Department of Physics, Peking University, Beijing 100871 (China); Chengdu Green Energy and Green Manufacturing Technology R and D Center, Chengdu, Sichuan Province 601207 (China); Jiang, Tao; Xie, Hua-mu; Zhao, Kui [Department of Physics, Peking University, Beijing 100871 (China); Besland, M.-P. [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France)

    2013-10-31

    We report a study of CuGa–In metallic precursors for chalcopyrite thin film. CuGa and In thin films were prepared by DC sputtering at room temperature. Due to low melting point of indium, the sputtering power on indium target was optimized. Then, CuGa and In multilayers were annealed at low temperature. At 120 °C, the annealing treatment could enhance diffusion and alloying of CuGa and In layers; however, at 160 °C, it caused a cohesion and crystalline of indium from the alloy which consequently formed irregular nodules on the film surface. The precursors were selenized to form copper indium gallium selenide (CIGS) thin films. The morphological and structural properties were investigated by scanning electron microscopy, X-ray diffraction and Raman spectra. The relationships between metallic precursors and CIGS films were discussed in the paper. A smooth precursor layer was the key factor to obtain a homogeneous and compact CIGS film. - Highlights: • An optimized sputtered indium film • An optimized alloying process of metallic precursor • An observation of nodules forming on the indium film and precursor surface • An observation of cauliflower structure in copper indium gallium selenide film • The relationship between precursor and CIGS film surface morphology.

  19. The control of disinfection byproducts and their precursors in biologically active filtration processes.

    Science.gov (United States)

    Liu, Chao; Olivares, Christopher I; Pinto, Ameet J; Lauderdale, Chance V; Brown, Jess; Selbes, Meric; Karanfil, Tanju

    2017-11-01

    While disinfection provides hygienically safe drinking water, the disinfectants react with inorganic or organic precursors, leading to the formation of harmful disinfection byproducts (DBPs). Biological filtration is a process in which an otherwise conventional granular filter is designed to remove not only fine particulates but also dissolved organic matters (e.g., DBP precursors) through microbially mediated degradation. Recently, applications of biofiltration in drinking water treatment have increased significantly. This review summarizes the effectiveness of biofiltration in removing DBPs and their precursors and identifies potential factors in biofilters that may control the removal or contribute to formation of DBP and their precursors during drinking water treatment. Biofiltration can remove a fraction of the precursors of halogenated DBPs (trihalomethanes, haloacetic acids, haloketones, haloaldehydes, haloacetonitriles, haloacetamides, and halonitromethanes), while also demonstrating capability in removing bromate and halogenated DBPs, except for trihalomethanes. However, the effectiveness of biofiltration mediated removal of nitrosamine and its precursors appears to be variable. An increase in nitrosamine precursors after biofiltration was ascribed to the biomass sloughing off from media or direct nitrosamine formation in the biofilter under certain denitrifying conditions. Operating parameters, such as pre-ozonation, media type, empty bed contact time, backwashing, temperature, and nutrient addition may be optimized to control the regulated DBPs in the biofilter effluent while minimizing the formation of unregulated emerging DBPs. While summarizing the state of knowledge of biofiltration mediated control of DBPs, this review also identifies several knowledge gaps to highlight future research topics of interest. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Opioid precursor protein isoform is targeted to the cell nuclei in the human brain

    DEFF Research Database (Denmark)

    Kononenko, Olga; Bazov, Igor; Watanabe, Hiroyuki

    2017-01-01

    Neuropeptide precursors are traditionally viewed as proteins giving rise to small neuropeptide molecules. Prodynorphin (PDYN) is the precursor protein to dynorphins, endogenous ligands for the κ-opioid receptor. We here describe two novel splicing variants of human PDYN mRNA. Expression of one...... isolated from human striatum using fluorescence-activated nuclei sorting, and by immunofluorescence staining and confocal microscopy in the human caudate nucleus. These results along with the presence of putative NLS in other neuropeptide precursors raise questions of the nuclear localization is a general...

  1. Mitigation of organic laser damage precursors from chemical processing of fused silica.

    Science.gov (United States)

    Baxamusa, S; Miller, P E; Wong, L; Steele, R; Shen, N; Bude, J

    2014-12-01

    Increases in the laser damage threshold of fused silica have been driven by the successive elimination of near-surface damage precursors such as polishing residue, fractures, and inorganic salts. In this work, we show that trace impurities in ultrapure water used to process fused silica optics may be responsible for the formation of carbonaceous deposits. We use surrogate materials to show that organic compounds precipitated onto fused silica surfaces form discrete damage precursors. Following a standard etching process, solvent-free oxidative decomposition using oxygen plasma or high-temperature thermal treatments in air reduced the total density of damage precursors to as low as silica.

  2. A case of withdrawal from the GHB precursors gamma-butyrolactone and 1,4-butanediol.

    Science.gov (United States)

    Schneir, A B; Ly, B T; Clark, R F

    2001-07-01

    We describe a case of withdrawal from the gamma hydroxybutyric acid (GHB) precursors gamma butyrolactone and 1,4-butanediol. Symptoms included visual hallucinations, tachycardia, tremor, nystagmus, and diaphoresis. Administration of benzodiazepines and phenobarbital successfully treated the withdrawal symptoms. As predicted from the metabolism of gamma butyrolactone and 1,4-butanediol to GHB, the symptoms were nearly identical to those reported from GHB withdrawal. Because GHB is now illegal in the United States, individuals have begun abusing the legal and easier to acquire GHB precursors. More frequent cases of both abuse and withdrawal from these GHB precursors can be expected.

  3. Correlation of precursor and product ions in single-stage high resolution mass spectrometry. A tool for detecting diagnostic ions and improving the precursor elemental composition elucidation

    Energy Technology Data Exchange (ETDEWEB)

    Borràs, S. [Departament de Química Analítica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona (Spain); Kaufmann, A., E-mail: anton.kaufmann@klzh.ch [Official Food Control Authority, Fehrenstrasse 15, 8032 Zürich (Switzerland); Companyó, R. [Departament de Química Analítica, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona (Spain)

    2013-04-15

    Highlights: ► We are describing a technique to spot ions which are derived from each other. ► Single stage high resolution data is used. ► This “in silicon” technique is compared to conventional precursor scan. ► Some applications for this technique are presented. -- Abstract: Monitoring of common diagnostic fragments is essential for recognizing molecules which are members of a particular compound class. Up to now, unit resolving tandem quadrupole mass spectrometers, operating in the precursor ion scan mode, have been typically used to perform such analysis. By means of high-resolution mass spectrometry (HRMS) a much more sensitive and selective detection can be achieved. However, using a single-stage HRMS instrument, there is no unequivocal link to the corresponding precursor ion, since such instrumentation does not permit a previous precursor selection. Thus, to address this limitation, an in silico approach to locate precursor ions, based on diagnostic fragments, was developed. Implemented as an Excel macro, the algorithm rapidly assembles and surveys exact mass data to provide a list of feasible precursor candidates according to the correlation of the chromatographic peak shape profile and other additional filtering criteria (e.g. neutral losses and isotopes). The macro was tested with two families of veterinary drugs, sulfonamides and penicillins, which are known to yield diagnostic product ions when fragmented. Data sets obtained from different food matrices (fish and liver), both at high and low concentration of the target compounds, were investigated in order to evaluate the capabilities and limitations of the reported approach. Finally, other possible applications of this technique, such as the elucidation of elemental compositions based on product ions and corresponding neutral losses, were also presented and discussed.

  4. Retrospective analysis for detecting seismic precursors in groundwater argon content

    Directory of Open Access Journals (Sweden)

    P. F. Biagi

    2004-01-01

    interpretation of the Kamchatkian anomalies as precursors.

  5. HAPs-Rx: Precombustion Removal of Hazardous Air Pollutant Precursors

    Energy Technology Data Exchange (ETDEWEB)

    David J. Akers; Clifford E. Raleigh

    1998-03-16

    CQ Inc. and its project team members--Howard University, PrepTech Inc., Fossil Fuel Sciences, the United States Geological Survey (USGS), and industry advisors--are applying mature coal cleaning and scientific principles to the new purpose of removing potentially hazardous air pollutants from coal. The team uniquely combines mineral processing, chemical engineering, and geochemical expertise. This project meets more than 11 goals of the U.S. Department of Energy (DOE), the National Energy Strategy, and the 1993 Climate Change Action Plan. During this project: (1) Equations were developed to predict the concentration of trace elements in as-mined and cleaned coals. These equations, which address both conventional and advanced cleaning processes, can be used to increase the removal of hazardous air pollutant precursors (HAPs) by existing cleaning plants and to improve the design of new cleaning plants. (2) A promising chemical method of removing mercury and other HAPs was developed. At bench-scale, mercury reductions of over 50 percent were achieved on coal that had already been cleaned by froth flotation. The processing cost of this technology is projected to be less than $3.00 per ton ($3.30 per tonne). (3) Projections were made of the average trace element concentration in cleaning plant solid waste streams from individual states. Average concentrations were found to be highly variable. (4) A significantly improved understanding of how trace elements occur in coal was gained, primarily through work at the USGS during the first systematic development of semiquantitative data for mode of occurrence. In addition, significant improvement was made in the laboratory protocol for mode of occurrence determination. (5) Team members developed a high-quality trace element washability database. For example, the poorest mass balance closure for the uncrushed size and washability data for mercury on all four coals is 8.44 percent and the best is 0.46 percent. This indicates an

  6. Measurements of Ozone Precursors in the Lake Tahoe Basin, USA

    Science.gov (United States)

    Zielinska, B.; Bytnerowicz, A.; Gertler, A.; McDaniel, M.; Rayne, S.; Burley, J. D.

    2014-12-01

    Lake Tahoe, located at 6,225 ft. (1,897 m) in the Sierra Nevada mountain range, is the largest alpine lake in North America. Known for the clarity of its water and the panorama of surrounding mountains on all sides, Lake Tahoe is a prime tourist attraction in the California - Nevada area. However, the Lake Tahoe Basin is facing significant environmental pollution problems, including declining water clarity and air quality issues. During the period of July 21 - 26, 2012, we conducted a field study in the Basin designed to characterize the precursors and pathways of secondary pollutant formation, including ozone and secondary organic aerosol (SOA). Four sites were selected; two were located at high elevations (one each on the western and eastern sides of the Basin) and two were positioned near the Lake level. Ozone and NO/NO2 concentrations were continuously measured. With a resolution of several hours over a 6-day sampling period canister samples were collected for detailed speciation of volatile organic compounds (VOC), 2,4-dinitrophenylhydrazine (DNPH) impregnated Sep-Pak cartridges for analysis of carbonyl compounds, PM2.5 Teflon and quartz filter samples for determination of mass, organic and elemental carbon (OC/EC) concentrations and speciation of organic compounds. Whereas the concentrations of lower molecular weight (mw) C2 - C3 hydrocarbons were generally the highest at all sampling sites, ranging from 25 to 76% of the total measured VOC (over 70 species from C2 to C10), the concentrations of biogenic hydrocarbons, isoprene and α-pinene were significant, ranging from 1.4 to 26% and 1.5 to 30%, respectively, of the total VOC. For comparison, the sum of benzene, toluene, ethylbenzene and xylenes (BTEX) constituted from 2.5 to 37% of the total VOC. All four sites showed maximum ozone concentrations in the range of 60 ppb. However, the lower sites show a pronounced diurnal pattern (i.e. maximum concentrations during the daytime hours, 0900 to 1700, with

  7. Small Lunar Lander - A Near Term Precursor Mission

    Science.gov (United States)

    Soppa, Uwe; Kyr, Peter; Bolz, Joerg; Bischof, Bernd

    In preparation of the Ministerial Conference in November 2008, the European Space Agency is currently developing a roadmap leading to the capability to sustain long term planetary exploration missions and manned missions to Moon and Mars. Embedded in the cornerstone missions of today's European planetary exploration program, which are marked by the two robotic Exo-Mars and Mars Sample Return missions, ESA has defined a Small Lunar Landing Mission serving as a precursor mission allowing to validate key enabling technologies for planetary exploration, while providing a scientific platform to Lunar exploration at the same time. In reply for the call for missions fitting into the mission time frame ranging from 2014 through 2016, EADS Astrium has proposed a Lunar Lander which can be launched by a Soyuz Fregat, combined with a programmatic planning with the goal being ready to fly within the given time. In the meantime, a European lunar exploration program has gained momentum such that the goals of the proposed mission have been expanded towards the preparation of technologies required for the logistics of lunar exploration including transportation to the Moon and back, building and supporting large scale outposts up to permanently manned bases. These key functions are the capability of autonomous, soft and precision landing, the Rendez-Vous in lunar orbit, plus the provision of surface mobility for science and logistic operations. The paper will first present the concept of the proposed Lunar Landing mission, describe the technical design and programmatic planning, and put it into context of the Mars Sample Return mission. The spacecraft shall be launched into the GTO by a Soyuz Fregat from the Kourou Space Center, and travel to the Moon from there on direct, 5 days transfer trajectory. The spacecraft is a single stage lander with the capability to autonomously perform all operations from launcher separation down to the lunar surface. A lunar rover shall provide

  8. Review on hydroxylamine, a precursor to amino-acids

    Science.gov (United States)

    Lemaire, Jean Louis

    2015-08-01

    Does life on earth come from interstellar space (IS)?It has been recently demonstrated that part of the terrestrial water is of IS origin [Cleeves et al. Science 2014]. This raises the question whether materials like amino-acids or their pre-biotic molecular precursors could have been formed and brought to earth in the same way than water. Another question is whether these molecules were formed in the gas phase or through reactions on the surface/volume of ice-covered grains. This may then have occurred in the vicinity of proto-stellar cores or deep into a pristine dense molecular clouds at very low temperatures.As far as bio-related molecules are concerned, chemistry with nitrogen-bearing molecules (like NH3 and NO) is involved. I review recent experimental work showing that hydroxylamine (NH2OH) could be formed either by surface or by volume reactions in conditions close to those prevailing in dense media. They use either electron-UV irradiation of water-ammonia ices [Zheng & Kaiser JCPA 2010] or successive hydrogenation of solid nitric oxide[Congiu, Fedoseev & al. ApJL.2012] or the simple oxidation of ammonia [He, Vidali, Lemaire & Garrod, ApJ, 2015] or the reaction of ammonia with hydroxyl radicals in a rare gas matrix [Zins & Krim, 2014, 69th ISMS]. A step further, the synthesis of the simplest amino-acids, glycine (NH2CH2COOH) and L- or D-alanine (NH2CH3CHCOOH) has already been obtained via reactions in the gas phase involving NH2OH+ [Blagojevic & al. MNRAS 2003].In addition to several earlier models demonstrating that the formation of all these molecules is possible in the gas phase, a new recent three-phase gas-grain chemical kinetics model of hot cores [Garrod ApJ 2013] shows that the results of ammonia oxidation we obtain are plausible by surface/volume reactions.Although none of the aforementioned molecules (except glycine in a sample of cometary origin) has been yet detected in the IS, they all are considered by many observers and modelers as likely

  9. TROPOMI on the Copernicus Sentinel 5 Precursor: Launched?

    Science.gov (United States)

    Levelt, P.; Veefkind, J. P.; Kleipool, Q.; Ludewig, A.; Aben, I.; De Vries, J.; Loyola, D. G.; Richter, A.; Van Roozendael, M.; Siddans, R.; Tamminen, J.; Wagner, T.; Nett, H.

    2016-12-01

    The Copernicus Sentinel 5 Precursor (S5P) is the first of the European Sentinels satellites dedicated to monitoring of the atmospheric composition. S5P is planned for launch in the 4thquarter of 2016; hopefully in time for the AGU Fall Meeting! The mission objectives of S5P are to monitor air quality, climate and the ozone layer, in the time period between 2017 and 2023. S5P will fly in a Sun-synchronized polar orbit with a 13:30 hr local equator crossing time. The single payload of the S5P mission is TROPOspheric Monitoring Instrument (TROPOMI), which is developed by The Netherlands in cooperation with the European Space Agency (ESA). TROPOMI is a nadir viewing shortwave spectrometer that measures in the UV-visible wavelength range (270-500 nm), the near infrared (710-770 nm) and the shortwave infrared (2314-2382 nm). TROPOMI will have an unprecedented spatial resolution of 7x7 km2at nadir. The spatial resolution is combined with a wide swath to allow for daily global coverage. The TROPOMI/S5P geophysical (Level 2) operational data products include nitrogen dioxide, carbon monoxide, ozone (total column, tropospheric column & profile), methane, sulfur dioxide, formaldehyde and aerosol and cloud parameters. The main heritage for TROPOMI comes from OMI on EOS Aura and SCIAMACHY on Envisat. Many of the lessons learned in these missions have resulted in design improvements for TROPOMI. One of the most striking features is the high spatial resolution of 7x7 km2at nadir. The high spatial resolution serves two goals: (1) emissions sources can be detected with a higher accuracy and (2) the number of cloud-free ground pixels will increase substantially. The higher spatial resolution is also combined with a significantly higher signal-to-noise ratio per ground pixel, compared to OMI. This will further enhance the capabilities of TROPOMI to detect small emissions sources. The S5P will fly in a so-called loose formation with the U.S. Suomi NPP (National Polar

  10. Utilizing online monitoring of water wells for detecting earthquake precursors

    Science.gov (United States)

    Reuveni, Y.; Anker, Y.; Inbar, N.; Yellin-Dror, A.; Guttman, J.; Flexer, A.

    2015-12-01

    be regarded as a reliable precursor, cross-correlating several anomalies can indicate to an imminent earthquake, with high degree of certainty.

  11. Identification of a novel type of processing sites in the precursor for the sea anemone neuropeptide Antho-RFamide (

    DEFF Research Database (Denmark)

    Schmutzler, C; Darmer, D; Diekhoff, D

    1992-01-01

    Neuropeptides are synthesized as large precursor proteins that undergo posttranslational cleavages and modifications to produce bioactive peptides. Here, we have cloned two closely related precursor proteins for the sea anemone neuropeptide Antho-RFamide (......Neuropeptides are synthesized as large precursor proteins that undergo posttranslational cleavages and modifications to produce bioactive peptides. Here, we have cloned two closely related precursor proteins for the sea anemone neuropeptide Antho-RFamide (...

  12. El efecto perverso del simulacro del consumo

    Directory of Open Access Journals (Sweden)

    Paulo De Tarso Riccordi

    2015-01-01

    Full Text Available Los domingos las Redes Globo y S.B.T. retienen entre el 60 y 70% de la audiencia nacional de Brasil. El autor resume la distribución de la pauta publicitaria entre los medios. Los marginados de la economía pueden acceder al consumo a través del simulacro televisivo o de la apropiación violenta. La televisión es uno de los componentes del proceso Deseo-Frustración-Revuelta, que forma parte de la historia urbana contemporánea de Brasil. El acceso casi mágico al producto publicitario, el simulacro del consumo que ofrecen los programas tipo "Silvio Santos" los múltiples sorteos y loterías oficiales y clandestinas, simultáneamente apaciguan y exaltan el deseo de consumir lo inaccesible.

  13. La luz del origen del universo

    Directory of Open Access Journals (Sweden)

    Casas, Alberto

    2015-10-01

    Full Text Available Penzias and Wilson discovered the cosmic microwave background, a luminous echo of the Big Bang, in 1965. The amount of information encoded in this relic of the early universe is truly extraordinary. At present, the most precise data about the origin and structure of the universe comes from the study of this primordial light, the full potential of which has yet to be explored.En 1965 se descubrió el fondo de radiación de microondas, un eco luminoso de la Gran Explosión (Big Bang. La cantidad de información contenida en esta reliquia del universo primitivo es verdaderamente extraordinaria. En la actualidad los datos más precisos sobre el origen y estructura del universo provienen del estudio de esta luz primigenia, que aún no ha sido explorada en todo su potencial.

  14. El desarrollo del libro álbum en Colombia: 1970 – 2008

    Directory of Open Access Journals (Sweden)

    Zully Pardo

    2010-03-01

    Full Text Available El desarrollo del libro álbum en Colombia es el tema principal del presente artículo en el que se expone, de manera muy general, el auge y desarrollo de la literatura infantil colombiana a partir de la década de los ochenta, haciendo hincapié en las colecciones nacionales de libro ilustrado y libro-álbum. Se exponen los trabajos precursores de este género, y las editoriales que marcaron una pauta, así como un panorama general de la situación actual.

  15. HACIA LA BÚSQUEDA DEL VERDADERO 1/IPÓL/TO UNAN VE

    OpenAIRE

    Gargurevich, Juan; Facultad de Letras y Ciencias Humanas de la Universidad Nacional Mayor de San Marcos

    2014-01-01

    Hipólito Unanue, gran personaje de la historia del Perú, tiene una biografía que merece ser revisada a profundidad y sin las concesiones tradicionales, aplicando métodos que nos ensefía la nueva historiografía. La psicohistoria de Erik Erikson es una propuesta que el autor aplica a la agitada vida del notable precursor, prócer y constructor de la República. Se abren así nuevas interrogantes sobre su actuación.

  16. El equilibrio del consumidor

    OpenAIRE

    León Rodríguez, Mª Dolores; Fernández Pérez, Ana Mª

    2008-01-01

    Obtencin de la recta presupuestaria de un consumidor. Definición y características de las Curvas de indiferencia. Concepto de relación marginal de sustitución. Obtención del equilibrio del consumidor

  17. Displasias del seno

    Directory of Open Access Journals (Sweden)

    Ernesto Andrade Valderrama

    1971-04-01

    Full Text Available En general, las Displasias no se presentan antes de la iniciación del estímulo Gonadal y tienden a desaparecer con el climaterio. Se definen entonces como las afecciones benignas del Seno, de origen endocrino.

  18. Elementos del sistema electoral del Congreso Mexicano

    OpenAIRE

    Medina García, Aldo; Cervantes Bravo, Irina

    2013-01-01

    El presente artículo es un estudio de los componentes del sistema electoral, diseñado por el legislador mexicano para integrar al parlamento federal. Estudio desarrollado a sabiendas de la importancia que reviste el sistema electoral como un medio que permite a los ciudadanos convertir su voto expresado en las urnas en escaños a favor de determinado candidato o partido. En dicho análisis tomamos en cuenta la evolución constitucional del sistema electoral mexicano, la participación de las fuer...

  19. En busca del ancestro : Arte constructivo y cantería escultórica inca

    OpenAIRE

    González De Nava, Enrique F.

    2006-01-01

    Fueron muchos los artistas europeos y americanos, precursores, iniciadores o herederos del arte moderno que, en la soledad de sus búsquedas-soledad autoasumida a la que se vieron arrojados por la bancarrota de la tradición renacentista- detectaron una filiación en modalidades extrañas a la corriente que se constituyera en Italia y en Flandes durante el siglo XV Facultad de Bellas Artes

  20. Avatares del comunicador complejo y fluido. Del perfil del comunicador social y otros devenires (Sandra Massoni)

    OpenAIRE

    Mariana Mascotti

    2016-01-01

    Avatares del comunicador complejo y fluido. Del perfil del comunicador social y otros devenires Sandra MASSONI — Editorial: Ediciones CIESPAL. Quito, Ecuador Año: 2016 Páginas: 212 ISBN: 978-9978-55-141-7

  1. Cobalt-lanthanum catalyst precursors for ammonia synthesis: determination of calcination temperature and storage conditions

    Directory of Open Access Journals (Sweden)

    Zybert Magdalena

    2017-06-01

    Full Text Available A thermal decomposition of a cobalt-lanthanum catalyst precursor containing a mixture of cobalt and lanthanum compounds obtained by co-precipitation were studied using thermal analysis coupled with mass spectrometry (TG-MS. Studies revealed that the calcination in air at 500°C is sufficient to transform the obtained cobalt precipitate into Co3O4, but it leads to only partial decomposition of lanthanum precipitate. In order to obtain Co/La catalyst precursor containing La2O3 the calcination in air at the temperature about 800°C is required. However, it is unfavorable from the point of view of textural properties of the catalyst precursor. A strong effect of storage conditions on the phase composition of the studied cobalt-lanthanum catalyst precursor, caused by the formation of lanthanum hydroxide and lanthanum carbonates from La2O3 when contacting with air, was observed.

  2. Altered β-Amyloid Precursor Protein Isoforms in Mexican Alzheimer’s Disease Patients

    Directory of Open Access Journals (Sweden)

    V. J. Sánchez-González

    2006-01-01

    Full Text Available Objective: To determine the β-amyloid precursor protein (βAPP isoforms ratio as a risk factor for Alzheimer’s Disease and to assess its relationship with demographic and genetic variables of the disease.

  3. The effect of precursor powder size on the microstructure and integranular properties of Bi2223 superconductors

    Directory of Open Access Journals (Sweden)

    I. Abdolhosseini

    2006-09-01

    Full Text Available  We have studied the effect of precursor powder size on the microstructure and intergranular behavior of polycrystalline Bi2223 superconductors using the XRD, SEM, electrical resistivity and AC susceptibility techniques. Polycrystalline Bi2223 superconductors were prepared from the powders with different milling times. The XRD results show that by decreasing the precursor powder size the Bi2223 phase fraction increases. It was found that the grain size and grain connectivity improved by decreasing the precursor powder size. Analysis of the temperature dependence of the AC susceptibility near the transition temperature (Tc has been done employing Beans critical state model. The observed variation of intergranular critical current densities (Jc with temperature indicates that the decreasing of precursor powder size in the Bi2223 system cases an increase in the intergranular critical current density.

  4. [Precursors and propeptides of neurotrophic factors as the modulators of biological activity of its mature forms].

    Science.gov (United States)

    Rafieva, L M; Shubin, A V; Gasanov, E V

    2012-01-01

    Here, we review the problems of neurotrophic factors' folding, the role of its precursors (proneurotrophins) and the contribution of elements deleted during its maturation (propeptides) in biological functioning of these growth factors.

  5. Investigation of isotopic linkages between precursor materials and the improvised high explosive product hexamethylene triperoxide diamine

    NARCIS (Netherlands)

    Lock, C.M.; Brust, G.M.H.; Breukelen, M. van; Dalmolen, J.; Koeberg, M.; Stoker, D.A.

    2012-01-01

    The results of isotope ratio mass spectrometry (IRMS) on hexamethylene triperoxide diamine (HMTD) and its precursor hexamethylenetetramine (hexamine) is presented. HMTD was prepared from hexamine using several different sources of hexamine under both controlled laboratory conditions and in field

  6. Searching and detecting earthquake geochemical precursors in CO2-rich groundwaters from Galicia, Spain

    National Research Council Canada - National Science Library

    PÉREZ, NEMESIO M; HERNÁNDEZ, P. A; IGARASHI, G; TRUJILLO, I; NAKAI, S; SUMINO, H; WAKITA, H

    2008-01-01

    ...), and these events changed the seismic hazard map used for the building code in Spain. Searching for earthquake precursors of these seismic events was performed, and precursory geochemical signatures of the 1995 and 1997 Galicia earthquakes were detected...

  7. Atomic layer deposition by reaction of molecular oxygen with tetrakisdimethylamido-metal precursors

    Energy Technology Data Exchange (ETDEWEB)

    Provine, J, E-mail: jprovine@stanford.edu; Schindler, Peter; Torgersen, Jan; Kim, Hyo Jin [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Karnthaler, Hans-Peter [Physics of Nanostructured Materials, University of Vienna, 1090 Vienna (Austria); Prinz, Fritz B. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-01-15

    Tetrakisdimethylamido (TDMA) based precursors are commonly used to deposit metal oxides such as TiO{sub 2}, ZrO{sub 2}, and HfO{sub 2} by means of chemical vapor deposition and atomic layer deposition (ALD). Both thermal and plasma enhanced ALD (PEALD) have been demonstrated with TDMA-metal precursors. While the reactions of TDMA-type precursors with water and oxygen plasma have been studied in the past, their reactivity with pure O{sub 2} has been overlooked. This paper reports on experimental evaluation of the reaction of molecular oxygen (O{sub 2}) and several metal organic precursors based on TDMA ligands. The effect of O{sub 2} exposure duration and substrate temperature on deposition and film morphology is evaluated and compared to thermal reactions with H{sub 2}O and PEALD with O{sub 2} plasma.

  8. On the precursors to the 2011 Tohoku earthquake: crustal movements and electromagnetic signatures

    Directory of Open Access Journals (Sweden)

    Makoto Kamiyama

    2016-03-01

    Full Text Available We compare the precursory behaviour of crustal movements with electromagnetic signatures for the 2011 off the Pacific Coast of Tohoku earthquake. First, we present the Global Positioning System (GPS data on the co-seismic variations and pre-seismic precursors (medium-term, short-term and imminent precursors. Then, we will review recently published results on electromagnetic precursors, including mainly short-term subionospheric very low frequency (VLF/LF propagation anomaly, ultralow frequency (ULF magnetic field depression and ULF/extremely low frequency (ELF atmospheric radiation. Finally, we examine the relationship between the crustal movements and electromagnetic phenomena. We conclude that at least short-term electromagnetic precursors are closely correlated in time with the corresponding crustal movements. This seems to provide evidence on the link between lithospheric and electromagnetic processes. Some discussions will be given on the possible mechanism of this link.

  9. Migratory appendicular muscles precursor cells in the common ancestor to all vertebrates.

    Science.gov (United States)

    Okamoto, Eri; Kusakabe, Rie; Kuraku, Shigehiro; Hyodo, Susumu; Robert-Moreno, Alexandre; Onimaru, Koh; Sharpe, James; Kuratani, Shigeru; Tanaka, Mikiko

    2017-11-01

    In amniote embryos, skeletal muscles in the trunk are derived from epithelial dermomyotomes, the ventral margin of which extends ventrally to form body wall muscles. At limb levels, ventral dermomyotomes also generate limb-muscle precursors, an Lbx1-positive cell population that originates from the dermomyotome and migrates distally into the limb bud. In elasmobranchs, however, muscles in the paired fins were believed to be formed by direct somitic extension, a developmental pattern used by the amniote body wall muscles. Here we re-examined the development of pectoral fin muscles in catsharks, Scyliorhinus, and found that chondrichthyan fin muscles are indeed formed from Lbx-positive muscle precursors. Furthermore, these precursors originate from the ventral edge of the dermomyotome, the rest of which extends towards the ventral midline to form body wall muscles. Therefore, the Lbx1-positive, de-epithelialized appendicular muscle precursors appear to have been established in the body plan before the divergence of Chondrichthyes and Osteichthyes.

  10. Cognitive and linguistic precursors to numeracy in kindergarten: Evidence from first and second language learners

    NARCIS (Netherlands)

    Kleemans, M.A.J.; Segers, P.C.J.; Verhoeven, L.T.W.

    2011-01-01

    The present study investigated the role of cognitive and linguistic precursors to early numeracy skills to examine the interrelations between the development of linguistic and numeracy skills. General intelligence, working memory, phonological awareness, grammatical ability, and early numeracy

  11. Precursors to potential severe core damage accidents. A status report, 1982--1983

    Energy Technology Data Exchange (ETDEWEB)

    Forester, J.A.; Mitchell, D.B.; Whitehead, D.W. [and others

    1997-04-01

    This study is a continuation of earlier work that evaluated 1969-1981 and 1984-1994 events affecting commercial light-water reactors. One-hundred nine operational events that affected 51 reactors during 1982 and 1983 and that are considered to be precursors to potential severe core damage are described. All these events had conditional probabilities of subsequent severe core damage greater than or equal to 1.0 x 10{sup {minus}6}. These events were identified by first computer screening the 1982-83 licensee event reports from commercial light-water reactors to select events that could be precursors to core damage. Candidates underwent engineering evaluation that identified, analyzed, and documented the precursors. This report discusses the general rationale for the study, the selection and documentation of events as precursors, and the estimation of conditional probabilities of subsequent severe core damage for the events.

  12. Review of solution precursor spray techniques applied to obtain ceramic films and coatings

    OpenAIRE

    Pawlowski, Lech; Pawłowski, Lech

    2014-01-01

    International audience; The review describes the techniques of film and coatings deposition using solution as a feedstock. After a short description of the processes of: (i) spray pyrolysis; (ii) solution precursor plasma spray (SPPS); and, (iii) solution precursor high velocity oxy-fuel, some properties of solution feedstock are discussed. The properties include the chemical composition of solutions used to synthesize typical coatings, which determine the flow of solution in a pipeline and i...

  13. Method for the preparation of carbon fiber from polyolefin fiber precursor, and carbon fibers made thereby

    Science.gov (United States)

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2015-08-04

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  14. B-Amyloid Precursor Protein Staining of the Brain in Sudden Infant and Early Childhood Death

    DEFF Research Database (Denmark)

    Jensen, Lisbeth Lund; Banner, Jytte; Ulhøi, Benedicte Parm

    2013-01-01

    To develop and validate a scoring method for assessing β-amyloid precursor protein (APP) staining in cerebral white matter and to investigate the occurrence, amount and deposition pattern based on the cause of death in infants and young children.......To develop and validate a scoring method for assessing β-amyloid precursor protein (APP) staining in cerebral white matter and to investigate the occurrence, amount and deposition pattern based on the cause of death in infants and young children....

  15. Vegfc Regulates Bipotential Precursor Division and Prox1 Expression to Promote Lymphatic Identity in Zebrafish

    DEFF Research Database (Denmark)

    Koltowska, Katarzyna; Lagendijk, Anne Karine; Pichol-Thievend, Cathy

    2015-01-01

    Lymphatic vessels arise chiefly from preexisting embryonic veins. Genetic regulators of lymphatic fate are known, but how dynamic cellular changes contribute during the acquisition of lymphatic identity is not understood. We report the visualization of zebrafish lymphatic precursor cell dynamics...... cell becomes lymphatic and progressively upregulates Prox1, and the other downregulates Prox1 and remains in the vein. Vegfc drives cell division and Prox1 expression in lymphatic daughter cells, coupling signaling dynamics with daughter cell fate restriction and precursor division....

  16. Conglomeración de precursores de tensión arterial elevada en adolescentes

    Directory of Open Access Journals (Sweden)

    Carlos M. Arango

    2014-09-01

    Conclusión: La conglomeración de dos o más precursores se asoció de manera significativa con la tensión arterial elevada, hallazgos que indican que se requieren intervenciones para reducir la presencia y acumulación de los precursores estudiados y así prevenir la adquisición de cifras de tensión arterial elevada en los adolescentes de Montería.

  17. Precursors to the Development of Anxiety Disorders in Young Children with Autism Spectrum Disorder

    Science.gov (United States)

    2015-10-01

    AWARD NUMBER: W81XWH-14-1-0527 TITLE: Precursors to the Development of Anxiety Disorders in Young Children with Autism Spectrum Disorder ...AND SUBTITLE 5a. CONTRACT NUMBER Precursors to the Development of Anxiety Disorders in Young Children with Autism Spectrum Disorder 5b. GRANT...focused on early detection and prevention of anxiety disorders in young children with ASD. II. Keywords Autism, Anxiety, Sensory Over-Responsivity

  18. Human iPSC-Derived GABA Ergic Precursor Cell Therapy for Chronic Epilepsy

    Science.gov (United States)

    2015-10-01

    AWARD NUMBER: W81XWH-14-1-0558 TITLE: Human iPSC-Derived GABA-Ergic Precursor Cell Therapy for Chronic Epilepsy PRINCIPAL INVESTIGATOR: Ashok K...AND SUBTITLE 5a. CONTRACT NUMBER Human iPSC-Derived GABA-Ergic Precursor Cell Therapy for Chronic Epilepsy 5b. GRANT NUMBER W81XWH-14-1-0558 5c...exhibiting chronic temporal lobe epilepsy (TLE) would: (1) greatly diminish the frequency and intensity of spontaneous recurrent seizures (SRS, Specific

  19. Proximal visceral endoderm and extraembryonic ectoderm regulate the formation of primordial germ cell precursors

    Directory of Open Access Journals (Sweden)

    Hayashi Katsuhiko

    2007-12-01

    Full Text Available Abstract Background The extraembryonic tissues, visceral endoderm (VE and extraembryonic ectoderm (ExE are known to be important for the induction of primordial germ cells (PGCs in mice via activation of the bone morphogenetic protein (BMP signalling pathway. We investigated whether the VE and ExE have a direct role in the specification of PGCs, or in an earlier event, namely the induction of the PGC precursors in the proximal posterior epiblast cells. Results We cultured embryonic day (E 5.75 to E7.0 mouse embryos in an explant-assay with or without extraembryonic tissues. The reconstituted pieces of embryonic and extraembryonic tissues were assessed for the formation of both PGC precursors and specified PGCs. For this, Blimp1:gfp and Stella:gfp transgenic mouse lines were used to distinguish between PGC precursors and specified PGC, respectively. We observed that the VE regulates formation of an appropriate number of PGC precursors between E6.25–E7.25, but it is not essential for the subsequent specification of PGCs from the precursor cells. Furthermore, we show that the ExE has a different role from that of the VE, which is to restrict localization of PGC precursors to the posterior part of the embryo. Conclusion We show that the VE and ExE have distinct roles in the induction of PGC precursors, namely the formation of a normal number of PGC precursors, and their appropriate localization during early development. However, these tissues do not have a direct role during the final stages of specification of the founder population of PGCs.

  20. Associations between musical abilities and precursors of reading in preschool aged children

    OpenAIRE

    Franziska eDegé; Claudia eKubicek; Gudrun eSchwarzer

    2015-01-01

    The association between music and language, in particular, the overlap in their processing results in the possibility to use one domain for the enhancement of the other. Especially in the preschool years music may be a valuable tool to train language abilities (e.g., precursors of reading). Therefore, detailed knowledge about associations between musical abilities and precursors of reading can be of great use for designing future music intervention studies that target language-related abiliti...

  1. Polymorphism of a polymer precursor: metastable glycolide polymorph recovered via large scale high-pressure experiments

    DEFF Research Database (Denmark)

    Hutchison, Ian B.; Delori, Amit; Wang, Xiao

    2015-01-01

    Using a large volume high-pressure press a new polymorph of an important precursor for biomedical polymers was isolated in gram quantities and used to seed crystallisation experiments at ambient pressure.......Using a large volume high-pressure press a new polymorph of an important precursor for biomedical polymers was isolated in gram quantities and used to seed crystallisation experiments at ambient pressure....

  2. Comparison of atopic cough with cough variant asthma: is atopic cough a precursor of asthma?

    OpenAIRE

    Fujimura, M; Ogawa, H.; Nishizawa, Y.; Nishi, K.

    2003-01-01

    Background: We have described a group of patients who present with isolated chronic bronchodilator resistant non-productive cough with an atopic constitution, eosinophilic tracheobronchitis, and airway cough receptor hypersensitivity without bronchial hyperresponsiveness, which we have termed "atopic cough". Although cough variant asthma (in which the cough responds to bronchodilators) is recognised as a precursor of typical asthma, it is not known whether atopic cough is also a precursor of ...

  3. Method for the preparation of carbon fiber from polyolefin fiber precursor

    Energy Technology Data Exchange (ETDEWEB)

    Naskar, Amit Kumar; Hunt, Marcus Andrew; Saito, Tomonori

    2017-11-28

    Methods for the preparation of carbon fiber from polyolefin fiber precursor, wherein the polyolefin fiber precursor is partially sulfonated and then carbonized to produce carbon fiber. Methods for producing hollow carbon fibers, wherein the hollow core is circular- or complex-shaped, are also described. Methods for producing carbon fibers possessing a circular- or complex-shaped outer surface, which may be solid or hollow, are also described.

  4. Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shafarman, William N. [Univ. of Delaware, Newark, DE (United States)

    2015-10-12

    This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phase agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.

  5. Polysialic acid bioengineering of neuronal cells by N-acyl sialic acid precursor treatment.

    Science.gov (United States)

    Pon, Robert A; Biggs, Nancy J; Jennings, Harold J

    2007-03-01

    The inherent promiscuity of the polysialic acid (PSA) biosynthetic pathway has been exploited by the use of exogenous unnatural sialic acid precursor molecules to introduce unnatural modifications into cellular PSA, and has found applications in nervous system development and tumor vaccine studies. The sialic acid precursor molecules N-propionyl- and N-butanoyl-mannosamine (ManPr, ManBu) have been variably reported to affect PSA biosynthesis ranging from complete inhibition to de novo production of modified PSA, thus illustrating the need for further investigation into their effects. In this study, we have used a monoclonal antibody (mAb) 13D9, specific to both N-propionyl-PSA and N-butanoyl-PSA (NPrPSA and NBuPSA), together with flow cytometry, to study precursor-treated tumor cells and NT2 neurons at different stages of their maturation. We report that both ManPr and ManBu sialic acid precursors are metabolized and the resultant unnatural sialic acids are incorporated into de novo surface sialylglycoconjugates in murine and human tumor cells and, for the first time, in human NT2 neurons. Furthermore, neither precursor treatment deleteriously affected endogenous PSA expression; however, with NT2 cells, PSA levels were naturally downregulated as a function of their maturation into polarized neurons independent of sialic acid precursor treatment.

  6. Four residues of propeptide are essential for precursor folding of nattokinase.

    Science.gov (United States)

    Jia, Yan; Cao, Xinhua; Deng, Yu; Bao, Wei; Tang, Changyan; Ding, Hanjing; Zheng, Zhongliang; Zou, Guolin

    2014-11-01

    Subtilisin propeptide functions as an intramolecular chaperone that guides precursor folding. Nattokinase, a member of subtilisin family, is synthesized as a precursor consisting of a signal peptide, a propeptide, and a subtilisin domain, and the mechanism of its folding remains to be understood. In this study, the essential residues of nattokinase propeptide which contribute to precursor folding were determined. Deletion analysis showed that the conserved regions in propeptide were important for precursor folding. Single-site and multi-site mutagenesis studies confirmed the role of Tyr10, Gly13, Gly34, and Gly35. During stage (i) and (ii) of precursor folding, Tyr10 and Gly13 would form the part of interface with subtilisin domain. While Gly34 and Gly35 connected with an α-helix that would stabilize the structure of propeptide. The quadruple Ala mutation, Y10A/G13A/G34A/G35A, resulted in a loss of the chaperone function for the propeptide. This work showed the essential residues of propeptide for precursor folding via secondary structure and kinetic parameter analyses. © The Author 2014. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.

  7. Synthesis and characterization of a boron-containing precursor for ZrB{sub 2} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Tao, X.Y.; Xiang, Z.; Zhou, S.; Zhu, Y. [China Univ. of Mining and Technology, Xuzhou (China). School of Materials Science and Engineering; Qiu, W.; Zhao, T. [Chinese Academy of Sciences, Beijing (China). Lab. of Advanced Polymer Materials

    2016-07-01

    A precursor for ZrB{sub 2} ceramic was successfully synthesized in a chemical reaction between polyzirconoxanesal (PZS) and boric acid. The molecular structure of the precursor, thermal properties and the pyrolysis behavior of the precursor were investigated. The results showed that the as-synthesized precursor was a polymer based on Zr-O-C-B bonds. The precursor was stable in air atmosphere and soluble in common organic solvents. The ceramic yield of the precursor at 1200 C was around 65.5 % under N{sub 2} atmosphere. The derived ceramics obtained at 1200 C were composed of B{sub 2}O{sub 3}, ZrO{sub 2} and carbon. When the temperature was increased up to 1300 C, peaks of ZrC emerged owing to carbothermal reduction. m-ZrO{sub 2} and t-ZrO{sub 2} disappeared when the pyrolysis temperature was increased to above 1400 C. ZrB{sub 2} became the predominant phase when the pyrolysis temperature was increased up to 1500 C.

  8. La crisi del diritto del lavoro

    Directory of Open Access Journals (Sweden)

    Alessandro Garilli

    2012-01-01

    Full Text Available Riassunto - L’Autore ripercorre in chiave critica l’evoluzione delle politiche legislative in materia di lavoro, alla luce dell’attuale fase di crisi economico finanziaria. Nell’esaminare i principali interventi normativi attuati da inizio secolo, l’Autore mette in evidenza le scelte di metodo e gli elementi di continuità che accomunano i vari provvedimenti, individuandoli nell’affannosa ricerca del punto di equilibrio tra flessibilità e garantismo. La riflessione si chiude con alcuni interrogativi sulle ultime linee di riforma del mercato del lavoro e con l’auspicio che, anche al cospetto delle imprescindibili ragioni dell’economia, il diritto del lavoro possa continuare a svolgere il proprio tradizionale ruolo di disciplina di tutela della persona.   Abstract - The author analyzes, with a critically oriented approach, the development of the employment law, in the light of the current economic and financial crisis. In examining the main regulatory measures implemented since the beginning of the century, the author highlights the methodological choices and the elements of continuity that unite the various measures, focusing them in a hard research of a point of balance between flexibility and security. The discussion concludes with some questions about the last lines of the reform of the labor market and with the hope that, even in the face of compelling reasons of economy, labor law can continue to play its traditional role of governing the protection of person.

  9. Elementos del sistema electoral del Congreso Mexicano

    Directory of Open Access Journals (Sweden)

    Aldo Medina García

    2013-07-01

    Full Text Available El presente artículo es un estudio de los componentes del sistema electoral, diseñado por el legislador mexicano para integrar al parlamento federal. Estudio desarrollado a sabiendas de la importancia que reviste el sistema electoral como un medio que permite a los ciudadanos convertir su voto expresado en las urnas en escaños a favor de determinado candidato o partido. En dicho análisis tomamos en cuenta la evolución constitucional del sistema electoral mexicano, la participación de las fuerzas minoritarias en la integración del Senado y de la Cámara de Diputados, la división que se hace del territorio en circunscripciones electorales, la barrera electoral que se fija a los partidos políticos para acceder a la representación en el Parlamento, la fórmula de asignación que se aplica a la votación obtenida, para finalmente concluir que el sistema electoral mexicano es esencialmente mayoritario aun cuando se vista de proporcional.

  10. Elementos del sistema electoral del Congreso Mexicano

    Directory of Open Access Journals (Sweden)

    Aldo Medina García

    2013-08-01

    Full Text Available El presente artículo es un estudio de los componentes del sistema electoral, diseñado por el legislador mexicano para integrar al parlamento federal. Estudio desarrollado a sabiendas de la importancia que reviste el sistema electoral como un medio que permite a los ciudadanos convertir su voto expresado en las urnas en escaños a favor de determinado candidato o partido. En dicho análisis tomamos en cuenta la evolución constitucional del sistema electoral mexicano, la participación de las fuerzas minoritarias en la integración del Senado y de la Cámara de Diputados, la división que se hace del territorio en circunscripciones electorales, la barrera electoral que se fija a los partidos políticos para acceder a la representación en el Parlamento, la fórmula de asignación que se aplica a la votación obtenida, para finalmente concluir que el sistema electoral mexicano es esencialmente mayoritario aun cuando se vista de proporcional.

  11. OBJETIVO DEL DESARROLLO DEL MILENIO 7

    Directory of Open Access Journals (Sweden)

    Margarita M. Pérez O.

    2013-10-01

    Full Text Available Los Objetivos de Desarrollo del Milenio, también conocidos como los Objetivos del Milenio, constituyeron las metas finales que aprobaron los dirigentes mundiales, 189 jefes de estado y de gobierno en la Cumbre del Milenio de las Naciones Unidas celebrada en Nueva York en el año 2000, en la cual los Estados miembros de la organización reafirmaron su compromiso de luchar por un mundo en el que el desarrollo sostenible y la eliminación de la pobreza tuvieran máxima prioridad1 . En la cumbre se definió la Declaración del Milenio, la cual detalla los objetivos, principios, valores, metas y acciones para erradicar la pobreza Mundial hacia el año 2015, todos ellos ratificados con alto interés y acción estratégica de carácter global, como marco para la medición de los progresos en materia de desarrollo.

  12. Los conquistadores del oro

    Directory of Open Access Journals (Sweden)

    José María de Heredia

    1967-11-01

    Full Text Available Este grandioso poema - el más monumental en la obra poética del príncipe parnasiano francés José Maria de Heredia-- aparece al final de todas las ediciones de LES TROPHEES, en seis capítulos de pareados alejandrinos: desde la primera (Lemerre, París, 1893 hasta la última, la suntuosa de Ferroud, ilustrada con acuarelas de Solomko (París, 1927. Es un testimonio relumbrante del apasionado interés y amor del poeta por el mundo occidental" en que naciera hijo de cubano y de francesa.

  13. Aspectos quirales del grafeno

    OpenAIRE

    H Torres-Silva; López-Bonilla,J.L

    2011-01-01

    El grafeno, una alotropía del carbono, es un logro de los avances de la nanotecnología. Siendo una nanoestructura, este componente estructural del grafito posee propiedades que lo han convertido en un potencial sustituto del silicio en el diseño y fabricación de circuitos integrados. Este artículo resume sus orígenes, posibilidades teóricas, así como sus propiedades prácticas. Se presentan aspectos teóricos de quiralidad en el grafeno, específicamente una teoría quiral para el grafeno, vincul...

  14. Diarrea del viajero

    OpenAIRE

    Melissa Beraun-Villa; Luis Manuel Valdez

    2013-01-01

    La diarrea del viajero es una de las condiciones que con mayor frecuencia afecta a los viajeros de países industrializados que visitan las zonas tropicales y subtropicales del planeta. El 20 a 50% de viajeros se van afectar por esta condición, siendo en ocasiones tan severa como para afectar los planes del viajero en la quinta parte de pacientes. El cuadro se manifiesta por la aparición de diarrea asociada a síntomas entéricos como dolor abdominal, nauseas, vómitos y en caso de diarrea inflam...

  15. Los sofismas del Naturalismo

    OpenAIRE

    Castillo Vegas, Juan

    2013-01-01

    Vamos a tratar de demostrar en el presente análisis que la verdadera falacia no se da en el iusnaturalismo sino en el naturalismo, por entender la naturaleza humana de una forma distorsionada. De este modo el iusnaturalismo es un aspecto del racionalismo, o mejor del intelectualismo, en el ámbito del Derecho, que ha ido despojando a los diversos modos de entender la naturaleza humana de los distintos errores que históricamente se le iban adhiriendo.   ABSTRACT We will try to show in this an...

  16. Hipertrofia del proceso coronoideo

    OpenAIRE

    Moretti, E.; I.O. Cal; M. Galetto; L. Londoño; Blanco, R.

    2014-01-01

    Entre las principales causas de la reducción progresiva y sin dolor de la apertura bucal en pacientes jóvenes, se encuentra la denominada hipertrofia del proceso coronoideo. Se trata de una patología secundaria a la elongación anormal del proceso coronoideo por el crecimiento del hueso que provoca una alteración mecánica al abrir la boca. Presentamos nuestra experiencia con la recogida de 5 casos clínicos.

  17. Del Pasadismo al Futurismo

    OpenAIRE

    Agudo-Martínez, M. J.

    2003-01-01

    Uno de los habituales prejuicios a la hora de abordar el análisis del movimiento futurista, al igual que sucede con el constructivismo, es la consideración del contexto político en el que se desarrollaron ambas vanguardias. Sin embargo, y dejando a un lado un enfoque del arte con finalidad política de signo diverso, habría que insistir en el hecho de que posiblemente sean tanto el futurismo italiano como el constructivismo ruso, los movimientos que con mayor entusiasmo se manifestaron, en un ...

  18. La muerte del mito

    OpenAIRE

    Sánchez-Biosca, Vicente

    1990-01-01

    Habría de ser de nuevo John Ford quien sentenciará la defunción del western en cuanto mito, su imposibilidad de construirse en el vacío de la historia. Y habría de ser en uno de los más lúcidos films de la historia del cine: The Man who shot Liberty Valance (El hombre que mató a Liberty Valance, 1962). Todo en este film posee un reverso: un viaje en ferrocarril abre paso al pueblecito de Shinbone. Pero, en el interior del relato, otro emprendido por el antes pionero y ho...

  19. Tratamiento del pie equino

    OpenAIRE

    Robles, Fernanda

    2012-01-01

    El pie equino varo es una patología frecuente en los pacientes con Encefalopatía crónica no evolutiva (ECNE).Se observó que existe una mayor frecuencia en el sexo masculino. Se realizó un estudio descriptivo, comparativo y secundario, durante el periodo de septiembre del 2006 a septiembre del 2011, con un total de 125 pacientes con Ecne, de los cuales se encontraron 101 con pie equino varo congénito. Objetivo: observar los resultados obtenidos en la rehabilitación del pie equino, en niños de ...

  20. Hipertrofia del proceso coronoideo

    Directory of Open Access Journals (Sweden)

    E. Moretti

    2014-06-01

    Full Text Available Entre las principales causas de la reducción progresiva y sin dolor de la apertura bucal en pacientes jóvenes, se encuentra la denominada hipertrofia del proceso coronoideo. Se trata de una patología secundaria a la elongación anormal del proceso coronoideo por el crecimiento del hueso que provoca una alteración mecánica al abrir la boca. Presentamos nuestra experiencia con la recogida de 5 casos clínicos.

  1. La intuición del análisis de redes de los militares españoles durante la guerra del Rif como método de lucha contra el contrabando de armas

    Directory of Open Access Journals (Sweden)

    Julián Antonio Paniagua López

    2016-06-01

    Full Text Available En este artículo se explica una de las estrategias que empleó el ejército español durante la guerra del Rif (1919-1926 para vigilar y evitar el contrabando de mercancías. Consistió en la vigilancia de determinados puntos y el camino que los unía, pero el sistema no estaba basado en el mapa concreto del territorio, sino en lo que en la actualidad se entiende como análisis de redes sociales, cuya primera obra propiamente dicha usando ese método fue publicada en 1934. Obviamente no fue una elaboración teórica ni sistemática en el análisis, sino una intuición del método, porque es muy improbable que los militares españoles de esa época hubieran recibido la formación correspondiente en la teoría matemática de grafos. Sin embargo, debido a la precisión de la información del contenido de los vínculos de cada nodo, la distinción de cuatro tipos de nodos y a la elaboración del gráfico, este trabajo debe ser considerado como precursor del método, al mismo nivel que el de otros precursores de la época

  2. "Storms of crustal stress" and AE earthquake precursors

    Directory of Open Access Journals (Sweden)

    G. P. Gregori

    2010-02-01

    Colfiorito – and (maybe in 2002 also the Molise earthquake can be reckoned to this "storm". During the "storm", started in 2008, the l'Aquila earthquake occurred.

    Additional logical analysis envisages the possibility of distinguishing some kind of "elementary" constituents of a "crustal storm", which can be briefly called "crustal substorms". The concept of "storm" and "substorm" is a common logical aspect, which is shared by several phenomena, depending on their common intrinsic and primary logical properties that can be called lognormality and fractality. Compared to a "crustal storm", a "crustal substorm" is likely to be reckoned to some specific seismic event. Owing to brevity purposes, however, the discussion of "substorms" is given elsewhere.

    AE is an effective tool for monitoring these phenomena, and other processes that are ongoing within the crust. Eventually they result to be precursors of some more or less violent earthquake. It should be stressed, however, that the target of AE monitoring is diagnosing the Earth's crust. In contrast, earthquake prediction implies a much different perspective, which makes sense only by means of more detailed multiparametric monitoring. An AE array can provide real physical information only about the processes that are objectively ongoing inside different and contiguous large slabs of the crust. The purpose is to monitor the stress propagation that crosses different regions, in order to envisage where and when it can eventually trigger a catastrophe of the system. The conclusion is that continental – or planetary – scale arrays of AE monitoring stations, which record a few different AE frequencies, appear to be the likely first step for diagnosing the evolution of local structures preceding an earthquake. On the other hand, as it is well known, the magnitude of the shock is to be related to the elastic energy stored in

  3. TP53 suppression promotes erythropoiesis in del(5q) MDS, suggesting a targeted therapeutic strategy in lenalidomide-resistant patients

    Science.gov (United States)

    Caceres, Gisela; McGraw, Kathy; Yip, Bon Ham; Pellagatti, Andrea; Johnson, Joseph; Zhang, Ling; Liu, Kenian; Zhang, Lan Min; Fulp, William J.; Lee, Ji-Hyun; Al Ali, Najla H.; Basiorka, Ashley; Smith, Larry J.; Daugherty, F. Joseph; Littleton, Neil; Wells, Richard A.; Sokol, Lubomir; Wei, Sheng; Komrokji, Rami S.; Boultwood, Jacqueline; List, Alan F.

    2013-01-01

    Stabilization of p53 in erythroid precursors in response to nucleosomal stress underlies the hypoplastic anemia in myelodysplastic syndromes (MDS) with chromosome 5q deletion [del(5q)]. We investigated whether cenersen, a clinically active 20-mer antisense oligonucleotide complementary to TP53 exon10, could suppress p53 expression and restore erythropoiesis in del(5q) MDS. Cenersen treatment of ribosomal protein S-14-deficient erythroblasts significantly reduced cellular p53 and p53-up-regulated modulator of apoptosis expression compared with controls, accompanied by a significant reduction in apoptosis and increased cell proliferation. In a two-stage erythroid differentiation assay, cenersen significantly suppressed nuclear p53 in bone marrow CD34+ cells isolated from patients with del(5q) MDS, whereas erythroid burst recovery increased proportionally to the magnitude of p53 suppression without evidence of del(5q) clonal suppression (r = −0.6; P = 0.005). To explore the effect of p53 suppression on erythropoiesis in vivo, dexamethasone, a glucocorticoid receptor-dependent p53 antagonist, was added to lenalidomide treatment in eight lower-risk, transfusion-dependent, del(5q) MDS patients with acquired drug resistance. Transfusion independence was restored in five patients accompanied by expansion of erythroid precursors and decreased cellular p53 expression. We conclude that targeted suppression of p53 could support effective erythropoiesis in lenalidomide-resistant del(5q) MDS. PMID:24043769

  4. Improved method for measuring transparent exopolymer particles (TEP) and their precursors infresh and saline water

    KAUST Repository

    Villacorte, Loreen O.

    2015-03-01

    Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and biological fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane fouling.

  5. Brainworkers: Trabajadores del conocimiento

    Directory of Open Access Journals (Sweden)

    Óscar Abellón García

    2004-02-01

    Full Text Available Los trabajadores del conocimiento realizan trabajos que requieren el empleo de la inteligencia, de la facultad de entender: son intelectuales. Se crecen ante los problemas complejos, aprecian la dificultad de la abstracción simplificada, juegan con modelos de realidades virtuales, razonan con transversalidad e intuición, son creativos e innovadores, transfieren informaciones y conceptos, en redes que vinculan conocimientos y amistades; manifiestan, en ese sentido, un espíritu renacentista. La mejor novedad que aporta el trabajador del conocimiento es su alto estado de alerta, su buen manejo de la información y por lo mismo es un guía en adaptación a los cambios del entorno. Las crisis de sectores son precisamente una prueba del funcionamiento ecosistémico de los procesos de cambio.

  6. Las identidades del dinero

    Directory of Open Access Journals (Sweden)

    CELSO SÁNCHEZ CAPDEQUÍ

    2005-01-01

    Full Text Available A lo largo del trabajo se ha pretendido desvelar los momentos sociales y simbólicos que constituyen la extensa biografía del dinero. En ausencia de una racionalidad económica diferenciada, el dinero nace, de forma no deliberada, en el templo bajo la atmósfera sacrificial, comparece en la modernidad como medio técnico que representa la esperanza del individuo propietario en la bonhomía del mercado como elemento pacificador de las costumbres sociales, y arriba a nuestra posmodernidad como fin en sí mismo que, convertido en bit desmaterializado, aspira a no dejar de circular por el nuevo espacio virtual.

  7. Diario del General Santander

    Directory of Open Access Journals (Sweden)

    Guillermo Hernández De Alba

    1963-06-01

    Full Text Available El doctor Rafael Martínez Briceño, eminente médico legista y abogado con notables títulos en la cultura colombiana como humanista y bibliófilo de rara erudición, posee una de las bibliotecas privadas más ricas del país, donde están representados en ediciones príncipes o rarísimas, los ingenios del Renacimiento y de la cultura universal del Barroco, así como las más raras ediciones impresas en hispanoamérica a partir del siglo XVI, especialmente relacionadas con las letras neogranadinas y colombianas.

  8. Actividad del virus del oeste del Nilo y otros flavivirus en cinco departamentos del Caribe colombiano

    Directory of Open Access Journals (Sweden)

    Jaime Álvarez

    2010-04-01

    Full Text Available El virus del oeste del Nilo (VON y el virus de la encefalitis de San Luis (VESL pertenece a la familia Flaviviridae, género Flavivirus y hacen parte del serocomplejo de la encefalitis japonesa (1. Estos virus se encuentran distribuidos en Estados Unidos, centro América y suramerica (2. Son mantenidos en la naturaleza en un ciclo enzoótico ave-mosquito-ave. Humanos, équidos y otros vertebrados se infectan por la picadura de mosquitos del genero Culex principalmente (1,2. En humanos se han identificado y descrito nuevos modos de transmisión de VON incluyendo infección a través de productos sanguíneos contaminados (3, transplante de órganos (4, transmisión a través de la leche materna (5, transmisión intrauterina (6, y exposición ocupacional (7.

  9. Preferencias del Turista

    Directory of Open Access Journals (Sweden)

    Jose Luis Leiva Olivencia

    2015-01-01

    Full Text Available Actualmente existen aplicaciones orientadas al turismo basadas en realidad aumentada, pero no integran técnicas de recomendación. Este articulo describe RAMCAT (Realidad Aumentada Móvil Contextual Aplicada al Turismo un modelo de guía turística, que recomienda puntos de interés, teniendo en cuenta factores como preferencias personales y atributos contextuales. Se presentan los componentes teóricos de la arquitectura propuesta, así como sus características, destacando la integración de diferentes sistemas de recomendación, que permiten añadir nuevos motores en el futuro. El articulo se centra en describir sus funcionalidades y el modulo correspondiente al sistema de recomendación basado en el perfil del turista. Otra característica importante del sistema propuesto es la retroalimentación del mismo mediante calificaciones del turista y su trazabilidad.

  10. Los muertos del Floreanismo

    Directory of Open Access Journals (Sweden)

    Enrique Ayala Mora

    2008-06-01

    Full Text Available El artículo analiza el crimen político durante las primeras décadas de vida de la República del Ecuador. Específicamente centra su estudio en el período dominado por la figura de Juan José Flores, primer presidente del Ecuador. La inestabilidad política, la precariedad de las alianzas entre las élites regionales, la crisis económica generada por las guerras de Independencia, las conspiraciones y la violencia que caracterizaron al período de surgimiento de las repúblicas andinas hicieron del crimen político un “vicio de nacimiento”. El asesinato del general Antonio José de Sucre, la muerte de los miembros de la sociedad El Quiteño Libre, el homicidio de Juan Otamendi, entre otros, hicieron patente esta característica.

  11. Niveles del aprendizaje organizacional

    OpenAIRE

    Garzón Castrillón, Manuel Alfonso

    2005-01-01

    En la propuesta de modelo de aprendizaje organizacional (AO), la segunda variable se denomina niveles del aprendizaje organizacional ; los niveles de aprendizaje que contemplamos para nuestra investigación son: individual, de equipo, organizacional e interorganizacional.

  12. La flecha del tiempo

    Directory of Open Access Journals (Sweden)

    César Gutiérrez Tapia

    2006-01-01

    Full Text Available El concepto del tiempo es muy importante en las ciencias naturales, especialmente en la Física. Entenderlo es muycomplejo ya que involucra una serie deproblemas que requieren de un análisis particular. Por ejemplo, definir la objetividad del tiempo, su dirección y métrica, elconcepto de “simultaneidad’’, entre otros. En este trabajo veremos que el concepto de ladirección del tiempo (flecha del tiempo no es posible plantearlo sin recurrir a la relación causa-efecto en el proceso irreversible de laevolución de la naturaleza y que el espacio-tiempo es una forma fundamental de la existencia de la materia.

  13. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available La millonaria contratación del futbolista David Beckham, un fenómeno del mercado, ha provocado cuestionamientos a los que se busca respuesta. Es tema de análisis el por qué el betseller "Harry Potter" ha causado tanta conmoción en la opinión pública. Respecto al periodista cibernético, se señalan los contornos del presente y atisban las posibilidades del futuro de esta nueva profesión. El tratamiento de los mitos de la prensa, los temores de la Ley mordaza venezolana y la brutalidad de los video juegos e Internet son temas de enorme interés. Se comenta las pocas veces que la prensa reflexiona sobre la comunicación corporal y la anorexia.

  14. Proceso de activación de precursores carbonosos esféricos y fibrosos para la retención en fase gas de compuestos orgánicos volátiles

    OpenAIRE

    Romero Anaya, Aroldo José

    2013-01-01

    Los compuestos orgánicos volátiles (COV) constituyen uno de los grupos de contaminantes atmosféricos más importantes, incluso a concentraciones bajas, por sus efectos nocivos. En el medio ambiente estos compuestos intervienen en la destrucción de la capa de ozono, son precursores de oxidantes fotoquímicos y son agentes responsables de la lluvia ácida y del cambio climático. Además, Las COV provocan enfermedades como el cáncer y mutaciones a nivel genético. Generalmente, los COV se producen en...

  15. Desarrollo del potencial humano

    Directory of Open Access Journals (Sweden)

    Hernando Bernal

    2015-01-01

    Full Text Available La actual coyuntura del mundo es la creación de un enorme y unitario mercado mundial. El desarrollo del potencial humano debe ser una prioridad de toda la sociedad. Es el único camino hacia la revolución de la esperanza.Intenta responder a la interrogante de si ¿Esta preparada la América Latina para ingresar al mercado mundial de los 90?

  16. Metafisica del cyberspace

    OpenAIRE

    Rossi, Diego

    2014-01-01

    Il titolo della tesi, Metafisica del cyberspace, intende la metafisica in una duplice accezione: il candidato, infatti, mira ad una comprensione dell’essenza metafisica di quel fenomeno che è indicato come cyberspace, provando, contemporaneamente, a decostruire l’impianto metafisico, tecnico, che finora ha condotto, generalmente, la trattazione del sistema info-mediatico della rete. Il lavoro si sviluppa in due ampie sezioni. La prima si concentra sul Denkweg heideggeriano, con il duplice ...

  17. Envejecimiento del sistema circadiano

    National Research Council Canada - National Science Library

    Lucas-Sánchez, Alejandro; Martinez-Nicolas, Antonio; Escames, Germaine; de Costa, Jorge

    2012-01-01

    ... este reloj interno se denomina sistema circadiano. Cuando a los organismos se les aísla del ambiente, sus ritmos difieren ligeramente de 24 horas, de ahí la denominación circa-diano . Por ello, para su correcto funcionamiento, el sistema requiere que se le ponga en hora cada día. Este sistema, al igual que el resto de órganos y sistemas del organism...

  18. El financiamiento del terrorismo

    OpenAIRE

    Díaz Molina, Jenory

    2008-01-01

    El sector financiero aplica actualmente medidas preventivas contra el delito de lavado de dinero. Hoy día es necesario ampliar esos controles para abarcar también el delito de financiamiento del terro - rismo, tomando en consideración las similitudes y diferencias entre ambos. Costa Rica recientemente tipificó el delito de financiamiento del te rrorismo con el fin de cumplir con compromisos internacionales

  19. Il problema del litio.

    Science.gov (United States)

    D'Antona, F.

    1995-03-01

    Contents: 1. Introduzione. 2. La nucleosintesi del Big Bang. 3. Il litio nelle stelle di popolazione II. 4. I modelli stellari standard. 5. Il litio negli ammassi aperti. 6. Meccanismi di distruzione "non standard". 7. I modelli non-standard applicati alla popolazione II. 8. L'evoluzione Galattica del litio. 9. Quali stelle producono litio? 10. Il litio come elemento chiave per dare un nome agli oggetti stellari più minuscoli. 11. Conclusioni.

  20. Filogenia del pie humano

    OpenAIRE

    Albiol Ferrer, Josep Maria

    1981-01-01

    El pie es un sistema complejo, estadio filogenético de una evolución, sometido permanentemente a tensiones musculares mantenedoras del equilibrio. La historia del ple humano empieza en cierta época muy lejana, calculada en unos 350 mi­llones de años, cuando, el primer anfibio emer­gió de la superfície de las aguas...

  1. Del excentrismo formalista al principio del montaje

    OpenAIRE

    Sánchez-Biosca, Vicente

    1994-01-01

    J.Mª Pozuelo sostenía que la contribución fundamental de la OPOIAZ consistió en la rentabilidad del término teórico desautomatización oponiéndolo al de mero desvío. Esta consideración de conjunto puede ponerse en relación con el fenómeno que se ha dado en llamar 'crisis de la literariedad'. Con esta expresión se levanta acta de la decadencia producida desde finales de los años sesenta del paradigma formalista de cuño inmanentista en beneficio de una multiplicidad de paradigmas que Darío Villa...

  2. El horror antes del horror

    OpenAIRE

    Jiménez-Varea, Jesús

    2009-01-01

    El autor de este ensayo precisa la definición y alcance del género del horror y establece qué elementos del mismo se trasfunden en las primeras historietas del siglo XX y cómo se deslizan y transforman en algunos personajes de los cómics americanos previos a la gran proliferación del género en los comic books.

  3. Carta del Editor

    Directory of Open Access Journals (Sweden)

    Luis Eladio Proaño

    2015-01-01

    Full Text Available El artículo de fondo busca esclarecer una posible manipulación de la información por parte del gobierno de Aznar sobre el ataque terrorista del 11 de marzo en Madrid, cuál fue la participación de los partidos políticos y cual la reacción del pueblo español. En otro tema se resalta la actividad cumplida por el CIESPAL en sus 45 años de labor. El tema de la lectura y el libro es abordado ante la aparición del e-book. Se habla sobre el ciberperiodismo, la prensa gratuita, las nuevas modalidades de programación en la radio dirigida a todos los públicos. En el cine se analiza "La pasión de Cristo" y el lauro que el festival de Cannnes otorgó a Fahrenheit 9/11. Desde la óptica de la informática agrega dos temas de actualidad: Los derechos digitales y el control del ciberespacio, más la penetración del Internet.

  4. el Valle del Cauca

    Directory of Open Access Journals (Sweden)

    Carlos Humberto Ortiz

    2007-01-01

    Full Text Available Este artículo se enfoca en la identi- ficación de aquellos factores estructurales que explican la pérdida de dinamismo económico de largo plazo en Colombia y, en particular, en el Valle del Cauca. Se examina la competitividad del Valle en relación con Colombia y con el resto del mundo. Se cuestiona la insistencia en una estrategia exportadora como dinamizadora del desarrollo económico. Se identifica que una gran parte de la población está excluida de los beneficios del desarrollo económico. Para construir un modelo de desarrollo que incluya a esta población se recomienda recuperar la senda de la industrialización, invertir en el capital humano (educación de alta calidad, salud, salubridad y nutrición, e invertir en infraestructura. La participación del Estado en estas inversiones sociales es necesaria para disminuir la desigualdad y aumentar el crecimiento económico.

  5. Gerencia del cuidado-gerencia del servicio

    Directory of Open Access Journals (Sweden)

    Marta Palmet Jiménez

    2016-01-01

    Full Text Available La gerencia de este siglo debe estar plenamente identificada con la administración para planear, organizar, decidir y obtener resultados definidos, evaluados y alcanzados a través de las personas. Para poder gerenciar el cuidado se debe saber administrar. El objetivo de enfermería es cuidar; el objetivo de la gerencia es la conducción de la producción de bienes o servicios en las organizaciones. La gerencia del cuidado implica: motivación, creatividad, responsabilidad y ética por parte del cuidador y de quien cuida, claridad de actitud frente al ser y al qué hacer por parte del cuidador. Se puede concluir que la gerencia (administración, el cuidado (producto de calidad, el servicio (valor intangible, querer servir son un trinomio que deben ir de la mano de manera integrada para el logro de los objetivos propuestos por la organización de salud y de enfermería.

  6. Evaluation of putative precursors of key 'reductive' compounds in wines post-bottling.

    Science.gov (United States)

    Bekker, Marlize Z; Wilkes, Eric N; Smith, Paul A

    2018-04-15

    Precursors to hydrogen sulfide (H2S), methanethiol (MeSH), ethanethiol (EtSH), and dimethyl sulfide (DMS) were assessed in wines post-bottling, and the percent yield of VSCs from each precursor determined. Cysteine (Cys) and glutathione (GSH) were associated with small increases in H2S concentrations, with a maximum yield of 0.18% and 1.3%, respectively. Greater yields of H2S were obtained from the combined Cys/GSH and copper treatments in white wine. Copper, acting on unknown precursors, was associated with large increases in H2S in Shiraz wines. Dimethyl disulfide and methyl thioacetate were important precursors to MeSH, and produced maximum yields of 72% and 33%, respectively. Ethyl thioacetate was a key precursor to EtSH, with a maximum yield of 39% obtained. Copper and pH were important in modulating MeSH and EtSH accumulation in wines. A maximum yield of 23% of DMS from S-methylmethionine was obtained, with dimethyl sulfoxide producing significantly less DMS with a maximum yield of only 9.4%. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Precursor of the Laughlin state of hard-core bosons on a two-leg ladder

    Science.gov (United States)

    Petrescu, Alexandru; Piraud, Marie; Roux, Guillaume; McCulloch, I. P.; Le Hur, Karyn

    2017-07-01

    We study hard core bosons on a two-leg ladder lattice under the orbital effect of a uniform magnetic field. At densities which are incommensurate with flux, the ground state is a Meissner state, or a vortex state, depending on the strength of the flux. When the density is commensurate with the flux, analytical arguments predict the possibility to stabilize a ground state of central charge c =1 , which is a precursor of the two-dimensional Laughlin state at ν =1 /2 . This differs from the coupled wire construction of the Laughlin state in that there exists a nonzero backscattering term in the edge Hamiltonian. By using a combination of bosonization and density matrix renormalization group (DMRG) calculations, we construct a phase diagram versus density and flux from local observables and central charge. We delimit the region where the finite-size ground state displays signatures compatible with this precursor to the Laughlin state. We show how bipartite charge fluctuations allow access to the Luttinger parameter for the edge Luttinger liquid corresponding to the precursor Laughlin state. The properties studied with local observables are confirmed by the long distance behavior of correlation functions. Our findings are consistent with an exact-diagonalization calculation of the many body ground state transverse conductivity in a thin torus geometry for parameters corresponding to the precursor Laughlin state. The model considered is simple enough such that the precursor to the Laughlin state could be realized in current ultracold atom, Josephson junction array, and quantum circuit experiments.

  8. Rejection of pharmaceutically-based N-nitrosodimethylamine precursors using nanofiltration.

    Science.gov (United States)

    Woods, Gwen C; Sadmani, A H M Anwar; Andrews, Susan A; Bagley, David M; Andrews, Robert C

    2016-04-15

    N-Nitrosodimethylamine (NDMA) is a disinfection by-product (DBP) with many known precursors such as amine-containing pharmaceuticals that can enter the environment via treated wastewater. Reverse osmosis and tight nanofiltration membranes (MW cutoff treatment technologies that demonstrate high removal of many compounds, but at relatively high energy costs. Looser membranes (>200 Da) may provide sufficient removal of a wide range of contaminants with lower energy costs. This study examined the rejection of pharmaceuticals that are known NDMA precursors (∼300 Da) using nanofiltration (MW cutoff ∼350 Da). MQ water was compared to two raw water sources, and results illustrated that NDMA precursors (as estimated by formation potential testing) were effectively rejected in all water matrices (>84%). Mixtures of pharmaceuticals vs. single-spiked compounds were found to have no impact on rejection from the membranes used. The use of MQ water vs. surface waters illustrated that natural organic matter, colloids, and inorganic ions present did not significantly impact the rejection of the amine-containing pharmaceuticals. This study illustrates that NDMA formation potential testing can be effectively used for assessing NDMA precursor rejection from more complex samples with multiple and/or unknown NDMA precursors present, such as wastewater matrices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. CXCR6 Expression Is Important for Retention and Circulation of ILC Precursors

    Directory of Open Access Journals (Sweden)

    Sylvestre Chea

    2015-01-01

    Full Text Available Innate lymphoid cells are present at mucosal sites and represent the first immune barrier against infections, but what contributes to their circulation and homing is still unclear. Using Rag2−/−Cxcr6Gfp/+ reporter mice, we assessed the expression and role of CXCR6 in the circulation of ILC precursors and their progeny. We identify CXCR6 expressing ILC precursors in the bone marrow and characterize their significant increase in CXCR6-deficient mice at steady state, indicating their partial retention in the bone marrow after CXCR6 ablation. Circulation was also impaired during embryonic life as fetal liver from CXCR6-deficient embryos displayed decreased numbers of ILC3 precursors. When injected, fetal CXCR6-deficient ILC3 precursors also fail to home and reconstitute ILC compartments in vivo. We show that adult intestinal ILC subsets have heterogeneous expression pattern of CXCR6, integrin α4β7, CD62L, CD69, and CD44, with ILC1 and ILC3 being more likely tissue resident lymphocytes. Intestinal ILC subsets were unchanged in percentages and numbers in both mice. We demonstrate that the ILC frequency is maintained due to a significant increase of ILC peripheral proliferation, as well as an increased proliferation of the in situ ILC precursors to compensate their retention in the bone marrow.

  10. Preparation and characterization of nano-cellulose with new shape from different precursor.

    Science.gov (United States)

    Maiti, Sonakshi; Jayaramudu, J; Das, Kunal; Reddy, Siva Mohan; Sadiku, Rotimi; Ray, Suprakas Sinha; Liu, Dagang

    2013-10-15

    Three different precursor materials - 1. China cotton, 2. South African cotton, 3. Waste tissue papers were used to produce nano-cellulose by acid hydrolysis route. No chemical pretreatment has been done for the production of nano-cellulose from these precursors. Prepared nano-cellulose and their corresponding precursor materials were characterized by transmission electron microscopy (TEM), particle size analysis, X-ray diffraction (XRD) study, thermo gravimetric analysis (TGA), differential scanning calorimetric (DSC) analysis and Fourier transformed infra red (FTIR) spectroscopy. A comparative study of the characteristics was done with the properties of raw materials and with that of nano-cellulose. Shape and size of the nano cellulose generally depends on nature of the precursor and hydrolysis condition. Morphology study of nano-cellulose from different sources revealed range of length from 50 to 200 nm and diameter from 10 to 90 nm. Higher thermal stability and crystallinity of nano-cellulose were observed compared to that of precursor from TGA/DSC study. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Contribution of constitutively proliferating precursor cell subtypes to dentate neurogenesis after cortical infarcts

    Directory of Open Access Journals (Sweden)

    Oberland Julia

    2010-11-01

    Full Text Available Abstract Background It is well known that focal ischemia increases neurogenesis in the adult dentate gyrus of the hippocampal formation but the cellular mechanisms underlying this proliferative response are only poorly understood. We here investigated whether precursor cells which constitutively proliferate before the ischemic infarct contribute to post-ischemic neurogenesis. To this purpose, transgenic mice expressing green fluorescent protein (GFP under the control of the nestin promoter received repetitive injections of the proliferation marker bromodeoxyuridine (BrdU prior to induction of cortical infarcts. We then immunocytochemically analyzed the fate of these BrdU-positive precursor cell subtypes from day 4 to day 28 after the lesion. Results Quantification of BrdU-expressing precursor cell populations revealed no alteration in number of radial glia-like type 1 cells but a sequential increase of later precursor cell subtypes in lesioned animals (type 2a cells at day 7, type 3 cells/immature neurons at day 14. These alterations result in an enhanced survival of mature neurons 4 weeks postinfarct. Conclusions Focal cortical infarcts recruit dentate precursor cells generated already before the infarct and significantly contribute to an enhanced neurogenesis. Our findings thereby increase our understanding of the complex cellular mechanisms of postlesional neurogenesis.

  12. P120-Catenin Regulates Early Trafficking Stages of the N-Cadherin Precursor Complex.

    Directory of Open Access Journals (Sweden)

    Diana P Wehrendt

    Full Text Available It is well established that binding of p120 catenin to the cytoplasmic domain of surface cadherin prevents cadherin endocytosis and degradation, contributing to cell-cell adhesion. In the present work we show that p120 catenin bound to the N-cadherin precursor, contributes to its anterograde movement from the endoplasmic reticulum (ER to the Golgi complex. In HeLa cells, depletion of p120 expression, or blocking its binding to N-cadherin, increased the accumulation of the precursor in the ER, while it decreased the localization of mature N-cadherin at intercellular junctions. Reconstitution experiments in p120-deficient SW48 cells with all three major isoforms of p120 (1, 3 and 4 had similar capacity to promote the processing of the N-cadherin precursor to the mature form, and its localization at cell-cell junctions. P120 catenin and protein tyrosine phosphatase PTP1B facilitated the recruitment of the N-ethylmaleimide sensitive factor (NSF, an ATPase involved in vesicular trafficking, to the N-cadherin precursor complex. Dominant negative NSF E329Q impaired N-cadherin trafficking, maturation and localization at cell-cell junctions. Our results uncover a new role for p120 catenin bound to the N-cadherin precursor ensuring its trafficking through the biosynthetic pathway towards the cell surface.

  13. Nondestructive Examination (NDE) Detection and Characterization of Degradation Precursors, Technical Progress Report for FY 2012

    Energy Technology Data Exchange (ETDEWEB)

    Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.; Prowant, M.S.; Coble, J.B.; Griffin, J.W.; Pitman, S.G.; Dahl, M.E.; Kafentzis, T.A.; Roosendaal, T.J.

    2012-09-01

    The overall objective of this project was to investigate the effectiveness of nondestructive examination (NDE) technology in detecting material degradation precursors by initiating and growing cracks in selected materials and using NDE methods to measure crack precursors prior to the onset of cracking. Nuclear reactor components are subject to stresses over time that are not precisely known and that make the life expectancy of components difficult to determine. To prevent future issues with the operation of these plants because of unforeseen failure of components, NDE technology is needed that can be used to identify and quantify precursors to macroscopic degradation of materials. Some of the NDE methods being researched as possible solutions to the precursor detection problem are magnetic Barkhausen noise, nonlinear ultrasonics, acoustic emission, eddy current measurements, and guided wave technology. In FY12, the objective was to complete preliminary assessment of advanced NDE techniques for sensitivity to degradation precursors, using prototypical degradation mechanisms in laboratory-scale measurements. This present document reports on the deliverable that meets the following milestone: M3LW-12OR0402143 – Report detailing an initial demonstration on samples from the crack-initiation tests will be provided (demonstrating acceleration of the work).

  14. Time-Resolved WAXD and FTIR Studies on Imidization-Induced Molecular Ordering in Polyimide Precursors

    Science.gov (United States)

    Ree, Moonhor; Shin, Tae Joo; Lee, Byeongdu; Wang, Xiaodong; Youn, Hwa Shik; Lee, Ki-Bong

    2000-03-01

    In general, aromatic polyimides are not melt-processable and not soluble in common solvents so that they are always processed in their soluble precursor forms and followed by imidization. Most poyimide precursors are poorly ordered in the solid state but molecular ordering develops during imidization. In this study, the imidization-induced molecular ordering in precursors of PMDA-ODA polyimide was examined in detail by time-resolved wide-angle X-ray diffraction using synchrotron radiation source at Pohang Accelerator Laboratory while the degree of imidization was monitored by time-resolved FT-IR spectroscopy. The imidization was conducted isothermally and non-isothermally over 20-400 C under nitrogen atmosphere. The imidization behavior was dependent on the precursor types: polyamic acid started to imidize at 120 C while polyamic diethyl ester began to imidize at 190 C. The molecular ordering was strongly dependent on the degree of imidization: the molecular ordering was found to be developed as the imidization began. The molecular ordering behavior will be discussed in detail with considering precursor types and their imidization kinetics. [This study was supported in part by the Ministry of Industry and the Ministry of Science & Technology (G7 Project Program) and by POSCO].

  15. Export of Precursor tRNAIle from the Nucleus to the Cytoplasm in Human Cells.

    Directory of Open Access Journals (Sweden)

    Min Wei

    Full Text Available In the current concept, tRNA maturation in vertebrate cells, including splicing of introns, trimming of 5' leader and 3' trailer, and adding of CCA, is thought to occur exclusively in the nucleus. Here we provide evidence to challenge this concept. Unspliced intron-containing precursor tRNAIle was identified in Human Immunodeficiency Virus type 1 (HIV-1 virions, which are synthesized in the cytoplasm. Northern blot, confocal microscopy and quantitative RT-PCR further verified enrichment of this unspliced tRNAIle within the cytoplasm in human cells. In addition to containing an intron, the cytoplasmic precursor tRNAIle also contains a short incompletely processed 5´ leader and a 3´ trailer, which abundance is around 1000 fold higher than the nuclear precursor tRNAIle with long 5' leader and long 3' trailer. In vitro data also suggest that the cytoplasmic unspliced end-immature precursor tRNAIle could be processed by short isoform of RNase Z, but not long isoform of RNase Z. These data suggest that precursor tRNAs could export from the nucleus to the cytoplasm in human cells, instead of be processed only in the nucleus.

  16. A protocol for isolation and enriched monolayer cultivation of neural precursor cells from mouse dentate gyrus

    Directory of Open Access Journals (Sweden)

    Harish eBabu

    2011-07-01

    Full Text Available In vitro assays are valuable tools to study the characteristics of adult neural precursor cells under controlled conditions with a defined set of parameters. We here present a detailed protocol based on our previous original publication (Babu et al., Enriched monolayer precursor cell cultures from micro-dissected adult mouse dentate gyrus yield functional granule cell-like neurons, PLoS One 2007, 2:e388 to isolate neural precursor cells from the hippocampus of adult mice and maintain and propagate them as adherent monolayer cultures. The strategy is based on the use of Percoll density gradient centrifugation to enrich precursor cells from the micro-dissected dentate gyrus. Based on the expression of Nestin and Sox2, a culture-purity of more than 98% can be achieved. The cultures are expanded under serum-free conditions in Neurobasal A medium with addition of the mitogens EGF and FGF2 as well as the supplements Glutamax-1 and B27. Under differentiation conditions, the precursor cells reliably generate approximately 30% neurons with appropriate morphological, molecular and electrophysiological characteristics that might reflect granule cell properties as their in vivo counterpart. We also highlight potential modifications to the protocol.

  17. Biosynthesis of poly(3-hydroxybutyrate) copolymers by Azotobacter chroococcum 7B: A precursor feeding strategy.

    Science.gov (United States)

    Bonartsev, A P; Zharkova, I I; Yakovlev, S G; Myshkina, V L; Mahina, T K; Voinova, V V; Zernov, A L; Zhuikov, V A; Akoulina, E A; Ivanova, E V; Kuznetsova, E S; Shaitan, K V; Bonartseva, G A

    2017-02-07

    A precursor feeding strategy for effective biopolymer producer strain Azotobacter chroococcum 7B was used to synthesize various poly(3-hydroxybutyrate) (PHB) copolymers. We performed experiments on biosynthesis of PHB copolymers by A. chroococcum 7B using various precursors: sucrose as the primary carbon source, various carboxylic acids and ethylene glycol (EG) derivatives [diethylene glycol (DEG), triethylene glycol (TEG), poly(ethylene glycol) (PEG) 300, PEG 400, PEG 1000] as additional carbon sources. We analyzed strain growth parameters including biomass and polymer yields as well as molecular weight and monomer composition of produced copolymers. We demonstrated that A. chroococcum 7B was able to synthesize copolymers using carboxylic acids with the length less than linear 6C, including poly(3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate) (PHB-4MHV) using Y-shaped 6C 3-methylvaleric acid as precursor as well as EG-containing copolymers: PHB-DEG, PHB-TEG, PHB-PEG, and PHB-HV-PEG copolymers using short-chain PEGs (with n ≤ 9) as precursors. It was shown that use of the additional carbon sources caused inhibition of cell growth, decrease in polymer yields, fall in polymer molecular weight, decrease in 3-hydroxyvalerate content in produced PHB-HV-PEG copolymer, and change in bacterial cells morphology that were depended on the nature of the precursors (carboxylic acids or EG derivatives) and the timing of its addition to the growth medium.

  18. Kinetic and Surface Study of Single-Walled Aluminosilicate Nanotubes and Their Precursors

    Directory of Open Access Journals (Sweden)

    Mauricio Molina

    2013-03-01

    Full Text Available The structural and surface changes undergone by the different precursors that are produced during the synthesis of imogolite are reported. The surface changes that occur during the synthesis of imogolite were determined by electrophoretic migration (EM measurements, which enabled the identification of the time at which the critical precursor of the nanoparticles was generated. A critical parameter for understanding the evolution of these precursors is the isoelectric point (IEP, of which variation revealed that the precursors modify the number of active ≡Al-OH and ≡Si-OH sites during the formation of imogolite. We also found that the IEP is displaced to a higher pH level as a consequence of the surface differentiation that occurs during the synthesis. At the same time, we established that the pH of the reaction (pHrx decreases with the evolution and condensation of the precursors during aging. Integration of all of the obtained results related to the structural and surface properties allows an overall understanding of the different processes that occur and the products that are formed during the synthesis of imogolite.

  19. Apparent absence of a benign precursor lesion: Implications for the pathogenesis of malignant melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Ross, P.M. (Rockefeller Univ., New York, NY (USA))

    1989-09-01

    This review relates concepts derived from the study of chemically induced skin cancer in animal models to the pathogenesis of malignant melanoma in humans. Most chemically induced experimental cancers in animals, including melanomas in rodents, arise within a benign precursor lesion. The initiation-promotion-progression sequence is a central concept in animal models for carcinogenesis. Many human melanomas appear to arise from epidermal melanocytes, with no associated precursor lesion. This article considers why there is no apparent precursor in many human melanomas and the consequences of this absence. Melanocyte physiology and factors that govern escape from defenses such as DNA repair, local tissue environment, and immunity presumably influence melanocyte conversion to melanoma. These factors may determine the absence of a precursor lesion in primary melanomas. In addition, it is possible that some human melanomas arise by cellular mechanisms different from those causing cancer in rodent models. Both molecular and prospective clinical studies will be required to explain this apparent paradox in the pathogenesis of melanoma. A similar approach may help to explain the origin of basal cell carcinoma and perhaps other human cancers that appear to arise directly from normal cells. From a clinical point of view, the absence of an identifiable, benign precursor lesion requires even greater emphasis on melanoma prevention. Research on mechanisms of ultraviolet carcinogenesis indicates that appropriate postexposure treatments may be useful in preventing long-term consequences of sunburn, including melanoma. 69 references.

  20. Growth and phase stabilization of HfO 2 thin films by ALD using novel precursors

    Science.gov (United States)

    Niinistö, Jaakko; Mäntymäki, Miia; Kukli, Kaupo; Costelle, Leila; Puukilainen, Esa; Ritala, Mikko; Leskelä, Markku

    2010-01-01

    HfO 2 thin films were grown at temperatures between 250 and 400 °C by atomic layer deposition using novel cyclopentadienyl-alkylamido precursors, namely CpHf(NMe 2) 3 and (CpMe)Hf(NMe 2) 3 (Cp, cyclopentadienyl=C 5H 5). Ozone was used as the oxygen source. The self-limiting growth mode was verified at 300 °C with a growth rate of 0.7-0.8 Å/cycle, depending on the precursor. Thermal decomposition started to have an effect on the growth mechanism at temperatures near 350 °C. As compared to the widely applied Hf(NEtMe) 4 precursor, these novel precursors with higher thermal stability resulted in HfO 2 films with lower impurity contents. The carbon and hydrogen contents below 0.5 and 1.0 at.%, respectively, were characterized for films deposited at 300 °C from both novel precursors. The 50-nm-thick HfO 2 films deposited at 300 °C or above were crystallized in mixture of monoclinic and cubic or tetragonal phases. Doping with low amounts of yttrium and subsequent annealing of 7-nm-thick film on TiN stabilized the preferred high-permittivity cubic or tetragonal phases, resulting in low capacitance equivalent thickness and leakage current density.

  1. Application of a global proteomic approach to archival precursor lesions: deleted in malignant brain tumors 1 and tissue transglutaminase 2 are upregulated in pancreatic cancer precursors

    DEFF Research Database (Denmark)

    Cheung, Wang; Darfler, Marlene M; Alvarez, Hector

    2008-01-01

    ,534 peptides corresponding to 523 unique proteins. A subset of 25 proteins was identified that had previously been reported as upregulated in pancreatic cancer. Immunohistochemical analysis for two of these, deleted in malignant brain tumors 1 (DMBT1) and tissue transglutaminase 2 (TGM2), confirmed......BACKGROUND: Pancreatic cancer is an almost uniformly fatal disease, and early detection is a critical determinant of improved survival. A variety of noninvasive precursor lesions of pancreatic adenocarcinoma have been identified, which provide a unique opportunity for intervention prior to onset...... of invasive cancer. Biomarker discovery in precursor lesions has been hampered by the ready availability of fresh specimens, and limited yields of proteins suitable for large scale screening. METHODS: We utilized Liquid Tissue, a novel technique for protein extraction from archival formalin-fixed material...

  2. Análisis del uso del precedente en fallos del Tribunal Contencioso Administrativo del Valle del Cauca

    Directory of Open Access Journals (Sweden)

    Alexander Atehortúa Rizo

    2007-12-01

    Full Text Available Desde 1991 la jurisdicción contenciosa administrativa es la encargada de emitir las sentencias que involucran responsabilidad estatal por fallas en la prestación de servicios públicos. Este artículo presenta la metodología y resultados de una investigación encaminada a examinar las líneas jurisprudenciales adoptadas por el Tribunal Contencioso Administrativo del Valle del Cauca en su tratamiento a demandas contra el Estado, especialmente en casos de perjuicios económicos debido a la crisis del cooperativismo y de responsabilidad por la muerte de reclusos en centros penitenciarios

  3. La imagen del pase.

    Directory of Open Access Journals (Sweden)

    Hernando Bernal.

    1999-11-01

    Full Text Available A partir de un texto del poeta Octavio Paz llamado «La imagen», se busca proseguir la equivalencia entre las imágenes de la poesía y la función que ellas tienen para el poeta, y el fantasma fundamental y su función para el analizante que está en el momento del pase. Se parte de la idea de que la poesía busca entrar en el ser así como el psicoanálisis tiene como finalidad apuntar al corazón del ser del sujeto. Se hace entonces una distinción del concepto de «ser» para el psicoanálisis, haciendo alusión también al discurso de la filosofía. Esclarecido el sentido de lo que es el «ser» para el psicoanálisis, se aborda de lleno – entre otras cosas, relacionadas con la experiencia del pase específicamente- la equivalencia entre la definición que hace Octavio Paz de «La Imagen» y el momento del pase en el análisis de un sujeto, imagen que, al igual que el mito para la filosofía, las leyes para la ciencia y el matema para el psicoanálisis, se constituyen en los instrumentos con los que cada una de estas disciplinas horadan en lo real.

  4. Elastic precursor wave decay in shock-compressed aluminum over a wide range of temperature

    Science.gov (United States)

    Austin, Ryan A.

    2018-01-01

    The effect of temperature on the dynamic flow behavior of aluminum is considered in the context of precursor wave decay measurements and simulations. In this regard, a dislocation-based model of high-rate metal plasticity is brought into agreement with previous measurements of evolving wave profiles at 300 to 933 K, wherein the amplification of the precursor structure with temperature arises naturally from the dislocation mechanics treatment. The model suggests that the kinetics of inelastic flow and stress relaxation are governed primarily by phonon scattering and radiative damping (sound wave emission from dislocation cores), both of which intensify with temperature. The manifestation of these drag effects is linked to low dislocation density ahead of the precursor wave and the high mobility of dislocations in the face-centered cubic lattice. Simulations performed using other typical models of shock wave plasticity do not reproduce the observed temperature-dependence of elastic/plastic wave structure.

  5. Discontinuous ZrO sub 2 fiber - Precursor solution chemistry-morphology relationship

    Energy Technology Data Exchange (ETDEWEB)

    Jada, S.S.; Bauer, J.F.

    1990-10-01

    Discontinuous ZrO{sub 2} fibers were produced by a rotary fiberization process using no added polymeric or organic viscosity modifiers to optimize spinning. Water-soluble fiber precursor powders derived from pH-modified solutions were utilized to achieve the requisite control of physical properties of the product. Detailed chemical and structural characterization of the precursor in solution and after sintering temperatures up to 850 C showed a high concentration of Zr-O-Zr bonding and corresponding low residual carbon (acetate) for samples derived from solution pH 6.58. During sintering the objective was to remove organic contaminates at very early stages of precursor fiber pyrolysis to gain control over phase transformation/composition and grain growth. Analysis of resulting spun fibers indicated that pH conditions can result in the formation of low temperature densified polycrystalline fibers comprised of a uniform distribution of fine-grained ZrO{sub 2}. 25 refs.

  6. Precursor models construction at preschool education: an approach to improve scientific education in the classroom

    Directory of Open Access Journals (Sweden)

    SABRINA PATRICIA CANEDO- IBARRA

    2010-07-01

    Full Text Available This study aimed to explore young children scientific precursor models construction and how the designed teaching strategy was successful for improving science learning at preschool in a social context. We describe how 6 years old children built a precursor model of flotation based on density. The exploratory study used a qualitative data collection and analysis following a pre-interview, instructional process and post-interview design. On analyzing children’s answers after the instructional period, we realized that several children were led to both the construction of a precursor model and a general qualitative upgrade in reasoning. We conclude that learning activities were effective and that the approach used in this study may help expand and improve teaching and learning of scientific concepts in preschool education

  7. T cell precursor migration towards beta 2-microglobulin is involved in thymus colonization of chicken embryos

    DEFF Research Database (Denmark)

    Dunon, D; Kaufman, J; Salomonsen, J

    1990-01-01

    beta 2-microglobulin (beta 2m) attracts hemopoietic precursors from chicken bone marrow cells in vitro. The cell population responding to beta 2m increases during the second period of thymus colonization, which takes place at days 12-14 of incubation. The precursors from 13.5 day old embryos were...... isolated after migration towards beta 2m in vitro and shown to be able to colonize a 13 day old thymus in ovo, where they subsequently acquire thymocyte markers. In contrast these beta 2m responsive precursors did not colonize embryonic bursa, i.e. differentiate into B lymphocytes. During chicken...... embryogenesis, peaks of beta 2m transcripts and of free beta 2m synthesis can only be detected in the thymus. The peak of free beta 2m synthesis in the thymus and the increase of beta 2m responding bone marrow cells both occur concomitantly with the second wave of thymus colonization in chicken embryo, facts...

  8. Cross-Correlation Earthquake Precursors in the Hydrogeochemical and Geoacoustic Signals for the Kamchatka Peninsula

    CERN Document Server

    Ryabinin, G V; Polyakov, Yu S; Timashev, S F

    2012-01-01

    We propose a new type of earthquake precursor based on the analysis of correlation dynamics between geophysical signals of different nature. The precursor is found using a two-parameter cross-correlation function introduced within the framework of flicker-noise spectroscopy, a general statistical physics approach to the analysis of time series. We consider an example of cross-correlation analysis for water salinity time series, an integral characteristic of the chemical composition of groundwater, and geoacoustic emissions recorded at the G-1 borehole on the Kamchatka peninsula in the time frame from 2001 to 2003, which is characterized by a sequence of three groups of significant seismic events. We found that cross-correlation precursors took place 27, 31, and 35 days ahead of the strongest earthquakes for each group of seismic events, respectively. At the same time, precursory anomalies in the signals themselves were observed only in the geoacoustic emissions for one group of earthquakes.

  9. Direct Genesis of Functional Rodent and Human Schwann Cells from Skin Mesenchymal Precursors

    Directory of Open Access Journals (Sweden)

    Matthew P. Krause

    2014-07-01

    Full Text Available Recent reports of directed reprogramming have raised questions about the stability of cell lineages. Here, we have addressed this issue, focusing upon skin-derived precursors (SKPs, a dermally derived precursor cell. We show by lineage tracing that murine SKPs from dorsal skin originate from mesenchymal and not neural crest-derived cells. These mesenchymally derived SKPs can, without genetic manipulation, generate functional Schwann cells, a neural crest cell type, and are highly similar at the transcriptional level to Schwann cells isolated from the peripheral nerve. This is not a mouse-specific phenomenon, since human SKPs that are highly similar at the transcriptome level can be made from neural crest-derived facial and mesodermally derived foreskin dermis and the foreskin SKPs can make myelinating Schwann cells. Thus, nonneural crest-derived mesenchymal precursors can differentiate into bona fide peripheral glia in the absence of genetic manipulation, suggesting that developmentally defined lineage boundaries are more flexible than widely thought.

  10. A review on remotely sensed land surface temperature anomaly as an earthquake precursor

    Science.gov (United States)

    Bhardwaj, Anshuman; Singh, Shaktiman; Sam, Lydia; Joshi, P. K.; Bhardwaj, Akanksha; Martín-Torres, F. Javier; Kumar, Rajesh

    2017-12-01

    The low predictability of earthquakes and the high uncertainty associated with their forecasts make earthquakes one of the worst natural calamities, capable of causing instant loss of life and property. Here, we discuss the studies reporting the observed anomalies in the satellite-derived Land Surface Temperature (LST) before an earthquake. We compile the conclusions of these studies and evaluate the use of remotely sensed LST anomalies as precursors of earthquakes. The arrival times and the amplitudes of the anomalies vary widely, thus making it difficult to consider them as universal markers to issue earthquake warnings. Based on the randomness in the observations of these precursors, we support employing a global-scale monitoring system to detect statistically robust anomalous geophysical signals prior to earthquakes before considering them as definite precursors.

  11. Treatment of Lignin Precursors to Improve their Suitability for Carbon Fibers: A Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Ryan [GrafTech International Holdings Inc.; Naskar, Amit [Oak Ridge National Laboratory; Gallego, Nidia [Oak Ridge National Laboratory; Dai, Xuliang [GrafTech International Holdings Inc.; Hausner, Andrew [GrafTech International Holdings Inc.

    2015-04-17

    Lignin has been investigated as a carbon fiber precursor since the 1960s. Although there have been a number of reports of successful lignin-based carbon fiber production at the lab scale, lignin-based carbon fibers are not currently commercially available. This review will highlight some of the known challenges, and also the reported methods for purifying and modifying lignin to improve it as a precursor. Lignin can come from different sources (e.g. hardwood, softwood, grasses) and extraction methods (e.g. organosolv, kraft), meaning that lignin can be found with a diversity of purity and structure. The implication of these conditions on lignin as carbon fiber precursor is not comprehensively known, especially as the lignin landscape is evolving. The work presented in this review will help guide the direction of a project between GrafTech and ORNL to develop lignin carbon fiber technology, as part of a cooperative agreement with the DOE Advanced Manufacturing Office.

  12. Preparation of Lanthanum Zirconate Coatings by the Solution Precursor Plasma Spray

    Science.gov (United States)

    Wang, W. Z.; Coyle, T.; Zhao, D.

    2014-06-01

    Solution precursor plasma spray (SPPS) can synthesize powders and deposit the coatings synchronously. The lanthanum zirconate coatings are deposited by SPPS in the present study, and the dense coating can be obtained through changing the precursor solution. The addition of urea can change the heat exchange process for some precursor mixtures. However, almost no effect can be found on the microstructure of powder and coating by the addition of urea. The extra heat energy caused by the addition of urea is so small, as compared with the heat input by the present plasma jet, so that the heating effect can be ignored. The porosity of coatings increase when the LaCl3·7H2O instead of La(NO3)3·6H2O reacts with Zr(CH3CO2)4.

  13. Endogenous peptide profile for elucidating biosynthetic processing of the ghrelin precursor.

    Science.gov (United States)

    Tsuchiya, Takashi; Iwakura, Hiroshi; Minamino, Naoto; Kangawa, Kenji; Sasaki, Kazuki

    2017-09-02

    Ghrelin is an orexigenic peptide primarily produced by gastric endocrine cells. The biosynthetic cleavage site of ghrelin has been well documented, but how its downstream region undergoes proteolytic processing remains poorly explored. Here, we provide the first snapshot of endogenous peptides from the ghrelin precursor by profiling the secretopeptidome of cultured mouse ghrelin-producing cells during exocytosis. Mapping of MS/MS sequenced peptides to the precursor highlighted three atypical monobasic processing sites, including the established C-terminus of ghrelin and the N-terminal cleavage site for obestatin, a putative 23-amino-acid C-terminally amidated peptide. However, we found that mouse obestatin does not occur in the form originally reported, but that a different amidation site is used to generate a shorter peptide. These data can be extended to study and characterize the precursor-derived peptides located downstream of ghrelin in different biological contexts. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Transcription factor Runx1 is pro-neurogenic in adult hippocampal precursor cells.

    Directory of Open Access Journals (Sweden)

    Hirokazu Fukui

    Full Text Available Transcription factor Runx1 (Runt Related Transcription Factor 1, plays an important role in the differentiation of hematopoetic stem cells, angiogenesis and the development of nociceptive neurons. These known functions have in common that they relate to lineage decisions. We thus asked whether such role might also be found for Runx1 in adult hippocampal neurogenesis as a process, in which such decisions have to be regulated lifelong. Runx1 shows a widespread low expression in the adult mouse brain, not particularly prominent in the hippocampus and the resident neural precursor cells. Isoforms 1 and 2 of Runx1 (but not 3 to 5 driven by the proximal promoter were expressed in hippocampal precursor cells ex vivo, albeit again at very low levels, and were markedly increased after stimulation with TGF-β1. Under differentiation conditions (withdrawal of growth factors Runx1 became down-regulated. Overexpression of Runx1 in vitro reduced proliferation, increased survival of precursor cells by reducing apoptosis, and increased neuronal differentiation, while slightly reducing dendritic morphology and complexity. Transfection with dominant-negative Runx1 in hippocampal precursor cells in vitro did not result in differences in neurogenesis. Hippocampal expression of Runx1 correlated with adult neurogenesis (precursor cell proliferation across BXD recombinant strains of mice and covarying transcripts enriched in the GO categories "neural precursor cell proliferation" and "neuron differentiation". Runx1 is thus a plausible candidate gene to be involved in regulating initial differentiation-related steps of adult neurogenesis. It seems, however, that the relative contribution of Runx1 to such effect is complementary and will explain only small parts of the cell-autonomous pro-differentiation effect.

  15. Improved method for measuring transparent exopolymer particles (TEP) and their precursors in fresh and saline water.

    Science.gov (United States)

    Villacorte, Loreen O; Ekowati, Yuli; Calix-Ponce, Helga N; Schippers, Jan C; Amy, Gary L; Kennedy, Maria D

    2015-03-01

    Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and biological fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane fouling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Uncertainty and variability in atmospheric formation of PFCAs from fluorotelomer precursors

    Science.gov (United States)

    Thackray, Colin P.; Selin, Noelle E.

    2017-04-01

    Perfluoroalkyl carboxylic acids (PFCAs) are environmental contaminants that are highly persistent, bio-accumulative, and have been detected along with their atmospheric precursors far from emissions sources. The importance of precursor emissions as an indirect source of PFCAs to the environment is uncertain. Modeling studies have used degradation mechanisms of differing complexities to estimate the atmospheric production of PFCAs, and these differing mechanisms lead to quantitatively different yields of PFCAs under differing atmospheric conditions. We evaluate PFCA formation with the most complete degradation mechanism to date, to our knowledge, using a box model analysis to simulate the atmospheric chemical fate of fluorotelomer precursors to long-chain PFCAs. In particular, we examine the variability in PFCA formation in different chemical environments, and estimate the uncertainty in PFCA formation due to reaction rate constants. We calculate long-chain PFCA formation theoretical maximum yields for the degradation of fluorotelomer precursor species at a representative sample of atmospheric conditions from a three-dimensional chemical transport model, and estimate uncertainties in such calculations for urban, ocean, and Arctic conditions using polynomial chaos methods. We find that atmospheric conditions farther from pollution sources have both higher capacities to form long-chain PFCAs and higher uncertainties in those capacities. Our calculations of theoretical maximum yields indicate that under typical Northern Hemisphere conditions, less than 10 % of emitted precursor may reach long-chain PFCA end products. This results in a possible upper bound of 2-50 t year-1 of long-chain PFCA (depending on quantity of emitted precursor) produced in the atmosphere via degradation of fluorotelomer products. However, transport to high-yield areas could result in higher yields. While the atmosphere is a potentially growing source of long-chain PFCAs in the Arctic, oceanic

  17. Norepinephrine directly activates adult hippocampal precursors via β3 adrenergic receptors

    Science.gov (United States)

    Jhaveri, Dhanisha J.; Mackay, Eirinn W.; Hamlin, Adam S.; Marathe, Swananda V.; Nandam, L. Sanjay; Vaidya, Vidita A.; Bartlett, Perry F.

    2010-01-01

    Adult hippocampal neurogenesis is a critical form of cellular plasticity that is greatly influenced by neural activity. Among the neurotransmitters that are widely implicated in regulating this process are serotonin and norepinephrine, levels of which are modulated by stress, depression and clinical antidepressants. However, studies to date have failed to address a direct role for either neurotransmitter in regulating hippocampal precursor activity. Here we show that norepinephrine but not serotonin directly activates self-renewing and multipotent neural precursors, including stem cells, from the hippocampus of adult mice. Mechanistically, we provide evidence that β3 adrenergic receptors, which are preferentially expressed on a Hes5-expressing precursor population in the subgranular zone (SGZ), mediate this norepinephrine-dependent activation. Moreover, intrahippocampal injection of a selective β3 adrenergic receptor agonist in vivo increases the number of proliferating cells in the SGZ. Similarly, systemic injection of the β adrenergic receptor agonist isoproterenol not only results in enhancement of proliferation in the SGZ but also leads to an increase in the percentage of nestin/glial fibrillary acidic protein double-positive neural precursors in vivo. Finally, using a novel ex vivo ‘slice-sphere’ assay that maintains an intact neurogenic niche, we demonstrate that antidepressants that selectively block the reuptake of norepinephrine, but not serotonin, robustly increase hippocampal precursor activity via β adrenergic receptors. These findings suggest that the activation of neurogenic precursors and stem cells via β3 adrenergic receptors could be a potent mechanism to increase neuronal production, providing a putative target for the development of novel antidepressants. PMID:20164362

  18. Photochemical CVD of Ru on functionalized self-assembled monolayers from organometallic precursors

    Science.gov (United States)

    Johnson, Kelsea R.; Arevalo Rodriguez, Paul; Brewer, Christopher R.; Brannaka, Joseph A.; Shi, Zhiwei; Yang, Jing; Salazar, Bryan; McElwee-White, Lisa; Walker, Amy V.

    2017-02-01

    Chemical vapor deposition (CVD) is an attractive technique for the metallization of organic thin films because it is selective and the thickness of the deposited film can easily be controlled. However, thermal CVD processes often require high temperatures which are generally incompatible with organic films. In this paper, we perform proof-of-concept studies of photochemical CVD to metallize organic thin films. In this method, a precursor undergoes photolytic decomposition to generate thermally labile intermediates prior to adsorption on the sample. Three readily available Ru precursors, CpRu(CO)2Me, (η3-allyl)Ru(CO)3Br, and (COT)Ru(CO)3, were employed to investigate the role of precursor quantum yield, ligand chemistry, and the Ru oxidation state on the deposition. To investigate the role of the substrate chemistry on deposition, carboxylic acid-, hydroxyl-, and methyl-terminated self-assembled monolayers were used. The data indicate that moderate quantum yields for ligand loss (φ ≥ 0.4) are required for ruthenium deposition, and the deposition is wavelength dependent. Second, anionic polyhapto ligands such as cyclopentadienyl and allyl are more difficult to remove than carbonyls, halides, and alkyls. Third, in contrast to the atomic layer deposition, acid-base reactions between the precursor and the substrate are more effective for deposition than nucleophilic reactions. Finally, the data suggest that selective deposition can be achieved on organic thin films by judicious choice of precursor and functional groups present on the substrate. These studies thus provide guidelines for the rational design of new precursors specifically for selective photochemical CVD on organic substrates.

  19. The elastic precursor behavior of tantalum under dynamic loading, its implications and modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Jow-Lian (Washington State University)

    2010-03-01

    When elastic-plastic materials, such as metals, are subjected to moderately high strain rates or dynamic loadings, the plastic stress wave trails behind the elastic wave because of its slower wave speed. Due to the inherent time-dependent nature of the plastic deformation, the elastic precursor generally loads the material to a metastable elastic state at a stres level that is higher than the static strength of the material. This metastable state gradually relaxes to the equilibrium state and the relaxation results in the so-called precursor decay. In a recent work by Asay et al. (J. Appl. Phys., 2009), the inelastic response of annealed and cold-rolled pure polycrystalline tantalum at intermediate strain rates ({approx} 106/sec) was experimentally characterized with ramp wave loading. It was found that the precursor of the annealed tantalum showed little decay over a propagation distance of 6 mm even though the peak precursor stress was well above the static strength of the mateiral. The precursor for the cold-rolled sample was more dispersive and did not exhibit the characteristics depicted by the annealed samples. In this study, a constitutive model based on the concept of dislocation motion and generation was developed to gain insights into this somewhat unusual precursor behavior, particularly for the annealed samples, and the possible underlying deformation mechanisms for tantalum. Despite its simplicity, the model worked quite well for both the annealed and cold-rolled materials. The tantalum studied here essentially exhibits strong rate sensitivity and this behavior is modeled through the low dislocation density and the strong stress dependence of the dislocation velocity. Both of these contributions may be related to the low mobility of the screw dislocations in bcc metals. This low mobility may result from its extended, three-dimensional core structure.

  20. Transcriptomic identification of starfish neuropeptide precursors yields new insights into neuropeptide evolution.

    Science.gov (United States)

    Semmens, Dean C; Mirabeau, Olivier; Moghul, Ismail; Pancholi, Mahesh R; Wurm, Yannick; Elphick, Maurice R

    2016-02-01

    Neuropeptides are evolutionarily ancient mediators of neuronal signalling in nervous systems. With recent advances in genomics/transcriptomics, an increasingly wide range of species has become accessible for molecular analysis. The deuterostomian invertebrates are of particular interest in this regard because they occupy an 'intermediate' position in animal phylogeny, bridging the gap between the well-studied model protostomian invertebrates (e.g. Drosophila melanogaster, Caenorhabditis elegans) and the vertebrates. Here we have identified 40 neuropeptide precursors in the starfish Asterias rubens, a deuterostomian invertebrate from the phylum Echinodermata. Importantly, these include kisspeptin-type and melanin-concentrating hormone-type precursors, which are the first to be discovered in a non-chordate species. Starfish tachykinin-type, somatostatin-type, pigment-dispersing factor-type and corticotropin-releasing hormone-type precursors are the first to be discovered in the echinoderm/ambulacrarian clade of the animal kingdom. Other precursors identified include vasopressin/oxytocin-type, gonadotropin-releasing hormone-type, thyrotropin-releasing hormone-type, calcitonin-type, cholecystokinin/gastrin-type, orexin-type, luqin-type, pedal peptide/orcokinin-type, glycoprotein hormone-type, bursicon-type, relaxin-type and insulin-like growth factor-type precursors. This is the most comprehensive identification of neuropeptide precursor proteins in an echinoderm to date, yielding new insights into the evolution of neuropeptide signalling systems. Furthermore, these data provide a basis for experimental analysis of neuropeptide function in the unique context of the decentralized, pentaradial echinoderm bauplan. © 2016 The Authors.

  1. Las carreras del futuro

    Directory of Open Access Journals (Sweden)

    Luis Piscoya Hermoza

    2011-07-01

    Full Text Available La primera década del siglo XXI ha estado signada por un énfasis en los estudiosde prospectiva, los mismos que, a partir de procesos de complejizacióny articulación de la sociedad planetaria como son la digitalización, el progresivodeterioro del medio ambiente, la necesidad del cambio de la matriz energéticay la globalización del mercado, han ensayado hipótesis para identificar lastendencias que se fortalecerán y profundizarán durante las próximas décadas.Desde el punto de vista metodológico, existen muchas maneras de clasificarlaspara conceptualizarlas y entenderlas mejor. Sin embargo, considerando lanaturaleza de esta edición nos proponemos enfocar directamente aquellas queestán estrechamente ligadas a la formación universitaria.Naturalmente, no pensamos que estamos ante tendencias inevitables en lamedida que epistemológicamente la creencia en leyes históricas deterministases insostenible y la práctica social nos muestra que la construcción del futuroes nuestra responsabilidad y siempre rebasa las mejores previsiones.

  2. La universidad del futuro

    Directory of Open Access Journals (Sweden)

    FERNANDO SANCÉN CONTRERAS

    2013-01-01

    Full Text Available El trabajo señala la necesidad de reconstruir la Universidad, dado el dinamismo que muestra la ciencia y la sociedad, pues trae consigo cambios sustanciales en la visión del mundo y en el aumento del poder del hombre sobre la naturaleza. Se analizan los supuestos epistemológicos de la universidad tradicional y se propone una nueva explicación del conocimiento humano, enfatizando el conocimiento científico. Postula una docencia fundada en las propiedades de la ciencia, cuyo método inductivo basado en los paradigmas vigentes: analítico, crítico, pragmático, ofrece una herramienta para la docencia, la investigación y la difusión de la cultura. Se propone una educación centrada en el sujeto que se hace a sí mismo (etopoiética y que insiste en el proceso de auto-creación del individuo y de la sociedad.

  3. Apostillas acerca del postrabajo

    Directory of Open Access Journals (Sweden)

    Arturo Torrecilla

    2000-04-01

    Full Text Available El más reciente debate en torno al postrabajo transforma la herencia de los dos ciclos que le precedieron desde los años setenta. El primero se correspondía con la crítica de la división social y técnica de labores informada por una filosofía de la alienación o bien por una rectificación de la arquitectónica marxista pero salvaguardando la promesa laborista del buen trabajo. El segundo ciclo hacía eco del rechazo a las cadenas de montaje fordistas y se abría al horizonte de la abolición del trabajo salarial, manteniendo sin embargo el abolengo del sujeto unitario de la historia. La presente escena asume una densidad mayor, producto del encuentro entre las nuevas tecnologías informacionales, las discusiones en el ámbito de la sociología y la antropología, de la tecnología y la ciencia, junto al dueto que inaugura el posmodernismo.

  4. Dalt del tren

    Directory of Open Access Journals (Sweden)

    Jaume Subirana

    2001-11-01

    Full Text Available Ens consta que la saviesa popular hi toca més del que a aquest temps d’enquestes, telèfons mòbils i targetes de crèdit li ve de gust admetre, per això em fa gràcia, en veure la pausada però continuada intrusió de la cultura catalana a Internet, recordar les cançons de quan era petit: “Dalt del tren, tots anem-hi dalt del tren, hi ha lloc per tota la gent”, dèiem, i “El tren pinxo de Banyoles és el més bonic que hi ha, ple de llaunes i cassoles i barrets de capellà”. I resulta que per una vegada a la vida hem pujat, efectivament, dalt del tren que passava per l’estació de Catalunya i en cinc anys hem passat de gairebé res a prou pàgines amb un contingut, a més, apreciable i, sobretot, a un petit teixit de persones i institucions que han entès la importància de la revolució comunicativa que Internet representa i que hi teixeixen i projecten webs amb el convenciment dels conversos.

  5. del Estado Aragua

    Directory of Open Access Journals (Sweden)

    Joselys Cintia Zerpa

    2008-01-01

    Full Text Available Diagnostica la situación actual de los bienes que conforman al patrimonio histórico-cultural del Municipio Zamora, Estado Aragua, Venezuela. La Investigación es descriptiva y de campo, comprendió la elaboración de un inventario de los bienes inmuebles, festividades religiosas y manifestaciones artesanales del municipio. Se estudiaron la condición física y uso actual de estos bienes y los planes y proyectos existentes. Analizó el marco normativo que los rige. Se obtuvo la opinión de los representantes de organismos públicos relacionados con la actividad turística del Municipio, de los visitantes, cronistas e historiadores. Aportes: La mayoría de los bienes se encuentran en buen estado de conservación, Las manifestaciones culturales, festividades y la artesanía se desarrollan periódicamente pero no son aprovechadas turísticamente, Se determinó que existe un marco normativo para tales bienes y No existen propuestas actuales referentes a estos bienes. Se reflejó el interés de los sectores institucional y privado para la incorporación de estos bienes a la oferta turística del Municipio y del Estado

  6. La espiral del mestizaje

    Directory of Open Access Journals (Sweden)

    Guillermo Cervantes

    2009-01-01

    Full Text Available El presente ensayo explora el papel jugado por el mestizaje como instrumento para forjar una identidad nacional en México; donde lo indígena convive y se fusiona con lo europeo, en la persecución y construcción de algo entendido propiamente como mexicano. Partiendo desde la época colonial en la Nueva España, abordaremos el papel concedido al indígena mexicano y su lenta inclusión en la sociedad mediante la adopción de prácticas consideradas como occidentales y civilizadas en detrimento de sus prácticas indígenas tradicionales, consideradas primitivas y atrasadas, como medio de asimilación. Fenómeno que más tarde habría de proponer al mestizo como estereotipo de la identidad nacional mexicana durante el siglo XIX; y que culminaría en su consolidación a principios del siglo XX. Así mismo se aborda la percepción del mestizaje como medio de civilización en la idiosincrasia del mexicano y del méxico-americano para culminar con una evolución de la constante búsqueda de lo occidental, esta vez mediante la asimilación al modo de vida estadounidense, como continuación del proceso civilizatorio entendido como mestizaje

  7. APOSTILLAS ACERCA DEL POSTRABAJO

    Directory of Open Access Journals (Sweden)

    Arturo Torrecilla

    2000-01-01

    Full Text Available El más reciente debate en torno al postrabajo transforma la herencia de los dos ciclos que le precedieron desde los años setenta. El primero se correspondía con la crítica de la división social y técnica de labores informada por una filosofía de la alienación o bien por una rectificación de la arquitectónica marxista pero salvaguardando la promesa laborista del buen trabajo. El segundo ciclo hacía eco del rechazo a las cadenas de montaje fordistas y se abría al horizonte de la abolición del trabajo salarial, manteniendo sin embargo el abolengo del sujeto unitario de la historia. La presente escena asume una densidad mayor, producto del encuentro entre las nuevas tecnologías informacionales, las discusiones en el ámbito de la sociología y la antropología, de la tecnología y la ciencia, junto al dueto que inaugura el posmodernismo.

  8. Gestión del riesgo del cambio (segunda parte Gestión del riesgo del cambio (segunda parte

    Directory of Open Access Journals (Sweden)

    Juan Pablo Zorrilla

    2007-07-01

    Full Text Available Segunda parte del artículo acerca del uso de futuros sobre el tipo de cambio. Esta continuación abarca estrategias, definiciones, metodología y explicaciones sobre todo lo relacionado con el Ratio de cobertura de los futuros y la aparición del riesgo base.Segunda parte del artículo acerca del uso de futuros sobre el tipo de cambio. Esta continuación abarca estrategias, definiciones, metodología y explicaciones sobre todo lo relacionado con el Ratio de cobertura de los futuros y la aparición del riesgo base.

  9. PRESENTE Y FUTURO DEL DERECHO DEL TRABAJO: BREVE HISTORIA JURÍDICA DEL DERECHO DEL TRABAJO EN COLOMBIA

    Directory of Open Access Journals (Sweden)

    Iván Daniel Jaramillo Jassir

    2010-11-01

    Full Text Available El acontecimiento jurídico del siglo XX, sin duda, lo constituye el nacimiento y consolidación de una disciplina jurídica que tiene por objeto regular la relación capital-trabajo en forma autónoma. El presente escrito tiene como finalidad describir las vicisitudes del nacimiento del derecho del trabajo y los procesos que han enmarcado la evolución de esta rama del derecho así como una descripción de las tendencias que experimenta esta disciplina en el inicio del siglo XXI.

  10. InSAR Measurement of Precursor and Post-Collapse Sinkhole Subsidence

    Science.gov (United States)

    Holley, Rachel; McCormack, Harry; Larkin, Hayley; Wooster, Michael; Thomas, Adam

    2016-08-01

    Sinkholes occur across the world, often posing an obvious hazard to communities, infrastructure and the environment. Regions prone to sinkhole formation can often be identified; however prediction of exact sinkhole locations and occurrences is exceedingly difficult. This case study from Wink, in the Permian Basin of Texas, demonstrates how InSAR can measure both precursor and post-collapse deformation associated with sinkholes. ERS, ALOS PALSAR and Sentinel-1A datasets are used to show precursor signals at least nine years before sinkhole formation, and post-collapse effects continuing over several decades. The rate of deformation is variable, but reaches many tens of centimetres per year during some periods.

  11. A C78 fullerene precursor: toward the direct synthesis of higher fullerenes.

    Science.gov (United States)

    Amsharov, Konstantin Yu; Jansen, Martin

    2008-04-04

    A C78 fullerene related structure (of C78:1 and C78:4, the last undiscovered C78 IPR isomer) has been synthesized and investigated as a pyrolytic precursor. The pyrolysis of precursor containing all 78 carbon atoms in the required positions and 93 of the 117 C-C bonds, needed for fullerene formation, showed selectivity for C78 fullerene formation. In independent experiments it has been shown that the flash pyrolysis of C78 fullerene is not affected by Stone-Wales rearrangement and loss of C2 fragments and, thus, is very promising for the synthesis of individual isomers of higher fullerenes.

  12. Backbone resonance assignments of the micro-RNA precursor binding region of human TRBP.

    Science.gov (United States)

    Benoit, Matthieu P M H; Plevin, Michael J

    2013-10-01

    TAR-RNA binding protein (TRBP) is a multidomain human protein involved in micro-RNA (miRNA) biogenesis. TRBP is a component of both the Dicer complex, which processes precursor miRNAs, and the RNA-induced silencing complex-loading complex. In addition, TRBP is implicated in the human immunodeficiency virus replication cycle and interferon-protein kinase R activity. TRBP contains 3 double-stranded RNA binding domains the first two of which have been shown to interact with miRNA precursors. Here we present the backbone resonance assignments and secondary structure of residues 19-228 of human TRBP2.

  13. Revealing the Formation of Copper Nanoparticles from a Homogeneous Solid Precursor by Electron Microscopy

    DEFF Research Database (Denmark)

    van den Berg, Roy; Elkjær, Christian Fink; Gommes, Cedric J.

    2016-01-01

    -and-growth scenario involving autocatalytic reduction of the copper phyllosilicate followed by diffusion-limited or reaction-limited growth of the copper nanoparticles. The plate-like structure of the precursor restricted the diffusion of copper and the autocatalytic reduction limited the probability for secondary...... nucleation. The combination of a uniform size of precursor particles and the autocatalytic reduction thus offers means to synthesize nanoparticles with well-defined sizes in large amounts. In this way, in situ observations made by electron microscopy provide mechanistic and kinetic insights...

  14. Unprocessed foot-and-mouth disease virus capsid precursor displays discontinuous epitopes involved in viral neutralization.

    OpenAIRE

    Sáiz, J C; Cairó, J; Medina, M.; Zuidema, D.; Abrams, C; Belsham, G.J.; Domingo, E; Vlak, J.M.

    1994-01-01

    A foot-and-mouth disease virus (FMDV) cDNA cassette containing sequences encoding the capsid precursor P1, peptide 2A and a truncated 2B (abbreviated P1-2A) of type C FMDV, has been modified to generate the authentic amino terminus and the myristoylation signal. This construct has been used to produce a recombinant baculovirus (AcMM53) which, upon infection of Spodoptera frugiperda insect cells, expressed a recombinant P1-2A precursor with a high yield. This polyprotein reacted with neutraliz...

  15. Enhanced production of scleroglucan by Sclerotium rolfsii MTCC 2156 by use of metabolic precursors.

    Science.gov (United States)

    Survase, Shrikant A; Saudagar, Parag S; Singhal, Rekha S

    2007-01-01

    The aim of this work was to study the effect of addition of different amino acids and sugar nucleotides as metabolic precursors on the production of scleroglucan. A maximum yield of 20.00 g/l and 22.32 g/l was obtained with optimized media supplemented with L-lysine (1.1 mM) and uridine mono-phosphate (UMP), respectively as compared to 16.52 g/l scleroglucan achieved with the control in the absence of metabolic precursors.

  16. Formation and Human Risk of Carcinogenic Heterocyclic Amines Formed from Natural Precursors in Meat

    Energy Technology Data Exchange (ETDEWEB)

    Knize, M G; Felton, J S

    2004-11-22

    A group of heterocyclic amines that are mutagens and rodent carcinogens form when meat is cooked to medium and well-done states. The precursors of these compounds are natural meat components: creatinine, amino acids and sugars. Defined model systems of dry-heated precursors mimic the amounts and proportions of heterocyclic amines found in meat. Results from model systems and cooking experiments suggest ways to reduce their formation and, thus, to reduce human intake. Human cancer epidemiology studies related to consumption of well-done meat products are listed and compared.

  17. Synthesis of higher sugars as precursors for the synthesis of chiral polyhydroxylated macrocyclic lactones

    Directory of Open Access Journals (Sweden)

    MARGARET HABASH-MARINO

    2000-07-01

    Full Text Available A general method for the synthesis of higher sugars that can be used as precursors for the synthesis of polyhydroxylated macrocyclic lactones (macrolides was described. The extension of the carbohydrate chain of a hexopyranose was effected at its C(6 hydroxymethyl carbon by coupling of two carbohydrate precursors via Wittig reaction. In this way 6,7-dideoxy-2,3,4,5,8,9,10-hepta-O-methyl-11-O-triphenylme-thyl-D-arabino-D-glucoundecanose diethyl dithioacetal (1 was synthesized as a model compound.

  18. Physical Property of Magnesium Doped Barium Hexaferrite Particles By Citrate Precursor Route In Presence Of Surfactants

    Science.gov (United States)

    Paladiya, Snehal; Chauhan, C. C.; Jotania, R. B.

    2010-12-01

    M-type Barium Magnesium hexaferrite with the composition BaMg2Fe10O19 was successfully prepared with and without surfactant by using a citrate precursor route. The obtained precursors were calcined at various temperatures. The crystalline structure, phase analysis and particle size were investigated by using X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) techniques. It is observed that the surfactant addition controls the microstructure of the formed Barium Magnesium hexaferrite particles and the type of surfactant plays a crucial role in deciding the morphology of particles.

  19. Deciphering the Enigma of Lignification: Precursor Transport, Oxidation, and the Topochemistry of Lignin Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Liu C. J.

    2012-03-01

    Plant lignification is a tightly regulated complex cellular process that occurs via three sequential steps: the synthesis of monolignols within the cytosol; the transport of monomeric precursors across plasma membrane; and the oxidative polymerization of monolignols to form lignin macromolecules within the cell wall. Although we have a reasonable understanding of monolignol biosynthesis, many aspects of lignin assembly remain elusive. These include the precursors transport and oxidation, and the initiation of lignin polymerization. This review describes our current knowledge of the molecular mechanisms underlying monolignol transport and oxidation, discusses the intriguing yet least-understood aspects of lignin assembly, and highlights the technologies potentially aiding in clarifying the enigma of plant lignification.

  20. Synthesis and characterization of zirconium diboride precursor based on polycentric bridge bonds

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Zhengfang, E-mail: xiezhengfang@163.com; Deng, Xiaojun, E-mail: dengxiaoj1314@163.com; Suo, Xingwen, E-mail: suoxw@126.com; Zhou, Ting, E-mail: ztcs51@126.com; Gou, Yanzi, E-mail: y.gou2012@hotmail.com

    2015-06-01

    Zirconium diboride (ZrB{sub 2}) is one of the most important ultrahigh temperature ceramics (UHTCs). ZrB{sub 2} precursor was synthesized with bis(cyclopentadienyl)zirconium dihydride (Cp{sub 2}ZrH{sub 2}) and borane-dimethyl sulfide complex (BH{sub 3}·S(CH{sub 3}){sub 2}). The influences of molar ratio of reactants and reaction temperature on the solubility of the as-synthesized precursors were investigated. The molecular structure of the precursor, pyrolysis behavior, and the composition of the derived ceramics were investigated by X-ray photoelectron spectroscopy (XPS), Fourier Transformed Infrared Spectroscopy (FT IR), Raman Spectroscopy (RMS), {sup 1}H Nuclear Magnetic Resonance Spectroscopy ({sup 1}H NMR), {sup 11}B Nuclear Magnetic Resonance Spectroscopy ({sup 11}B NMR), Thermogravimetric-Mass Spectroscopy (TG-MS), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), respectively. The results showed that, the precursor was an oligomer based on Zr–H–B polycentric bridge bonds with molecular weight of 750 and formula as (Cp{sub 2}Zr(BH{sub 4}){sub 2}){sub 3}. The precursor would probably further polymerize under vacuum or at high temperature and lead to an insoluble polymer. The ceramic yield of the precursor at 1000 °C was around 66% under N{sub 2} atmosphere. After pyrolyzed at 1800 °C, the derived ceramics were composed of h-ZrB{sub 2}, ZrC, and free carbon with a formula as ZrB{sub 1.38}C{sub 2.18}. - Highlights: • ZrB{sub 2} precursor based on Zr–H–B polycentric bridge bonds was synthesized. • The ceramic yield of the precursor at 1000 °C was around 66% under N{sub 2} atmosphere. • After pyrolyzed at 1800 °C, the derived ceramics were composed of h-ZrB{sub 2}, ZrC and free carbon with a formula as ZrB{sub 1.38}C{sub 2.18}.

  1. En defensa del arte del performance

    Directory of Open Access Journals (Sweden)

    Guillermo Gómez-Peña

    2005-12-01

    Full Text Available ¿Qué es "exactamente" el arte del performance? Y ¿qué es lo que hace a un artista de performance ser, pensar y actuar como tal? En este texto, intentaré responder estas preguntas de manera elíptica, creando un bosquejo poético de un performero parado sobre el mapa del arte del performance en el nuevo siglo, según como yo lo percibo. Para ser congruente con mi propia práctica estética, al tiempo que intento responder a estas espinosas preguntas, atravesaré constantemente las fronteras entre la teoría y la crónica; entre los escabrosos terrenos de lo personal y lo social (entre el "yo" y el "nosotros", con la esperanza de descubrir algunas encrucijadas y puentes interesantes. Trataré de escribir con toda la pasión, el valor y la claridad que pueda, aún que la naturaleza resbaladiza y en permanente transformación de este 'campo' nos dificulta en extremo trazar definiciones simplistas.What does it mean performance art? What does it make a performance artist to think, be and act as such? In this text, I will try to answer these questions in a somewhat elliptic fashion, as if it were a poetic essay of a performer standing over the map of performance art in the new century, as I perceive it. In order to be consistent with my own aesthetic practice, at the same time that I attempt to answer these thorny questions, I will constantly cross the frontiers between theory and chronicle; between the frightening fields of the personal and the social ( between "I" and "we", hoping to discover some interesting bridges and crossroads. I will write with all possible passion, value and clarity though the sliding nature and constant transformation of this 'field' make it extremely difficult to come with simplistic definitions.

  2. Holocene North Atlantic Deep Water variability through a centennial-scale study of its precursor watermasses

    Science.gov (United States)

    Hall, I.; Bianchi, G.; Evans, J.; Cortijo, E.; Keigwin, L.; Schonfeld, J.

    2003-04-01

    significant ISOW perturbations during the 8.2 event is found, both and C. wuellerstorfi stable isotopic records display the sharpest Holocene deviation from mean values at ~7.5-7.3 ka. Regionally, this corresponds with significant peaks in IRD sedimentation and precipitation/mean annual air temperature during the Holocene. Planktonic del18O (G. bulloides) and grain size records suggest a cooling of surface waters and slowing down of ISOW corresponding with the Little Ice Age. We also present our initial integration of the radiocarbon-dated record of NEAP-4K with the equivalent proxy records from the other three localities based on a provisional correlation while we await the results on 30 further dates. These preliminary data allow a qualitative assessment of the relative contribution that each individual precursor watermass makes towards the composite NADW flow. Such evidence should help in making a more accurate identification of the source(s) and processes involved in Holocene thermohaline instability.

  3. Fractura triple del complejo suspensorio del hombro

    OpenAIRE

    Eraclio Delgado Rifá; Héctor Gabriel Díaz Carrillo; Manuel Miranda Digón

    2015-01-01

    El complejo suspensorio del hombro es una estructura sumamente importante, compuesta por un anillo de huesos y tejidos blandos. Las lesiones aisladas de este complejo anatómico son frecuentes y no afectan su estabilidad. La interrupción doble conduce a la inestabilidad de esta estructura y usualmente requiere tratamiento quirúrgico. La triple interrupción, por su parte, es sumamente rara y es encontrada en casos de trauma de alta energía a menudo en asociación con otras lesiones. Se presenta ...

  4. Dignidad y autodeterminacion fisica como fundamento del estatuto del paciente

    National Research Council Canada - National Science Library

    Gomez Sanchez, Yolanda

    2011-01-01

    ... con los derechos de las personas. Se analizan los conceptos de dignidad y libertad individual como fundamentos necesarios del estatuto del paciente y se defiende que la libertad de la persona se manifiesta en el ambito biome-dico...

  5. Aberraciones citogeneticas en cultivos primarios del epitelio superficial del ovario

    National Research Council Canada - National Science Library

    Chuaire-Noack, Lilian; Rondon-Lagos, Sandra; Ramirez-Corredor, Amparo; Ibanez-Pinilla, Milciades; Ramirez-Clavijo, Sandra

    2010-01-01

    El objetivo del presente trabajo fue determinar la presencia de anormalidades cromosomicas en cultivos primarios de celulas del epitelio superficial ovarico en mujeres de diferentes edades, sin antecedentes de cancer...

  6. Mouse ES cell-derived cardiac precursor cells are multipotent and facilitate identification of novel cardiac genes

    National Research Council Canada - National Science Library

    Christoforou, Nicolas; Miller, Ronald A; Hill, Christine M; Jie, Chunfa C; McCallion, Andrew S; Gearhart, John D

    2008-01-01

    Although the differentiation of ES cells to cardiomyocytes has been firmly established, the extent to which corresponding cardiac precursor cells can contribute to other cardiac populations remains unclear...

  7. In situ Precursor-Template Route to Semi-Ordered NaNbO3 Nanobelt Arrays.

    Science.gov (United States)

    Wu, Junshu; Xue, Dongfeng

    2011-12-01

    We exploited a precursor-template route to chemically synthesize NaNbO3 nanobelt arrays. Na7(H3O)Nb6O19·14H2O nanobelt precursor was firstly prepared via a hydrothermal synthetic route using Nb foil. The aspect ratio of the precursor is controllable facilely depending on the concentration of NaOH aqueous solution. The precursor was calcined in air to yield single-crystalline monoclinic NaNbO3 nanobelt arrays. The proposed scheme for NaNbO3 nanobelt formation starting from Nb metal may be extended to the chemical fabrication of more niobate arrays.

  8. La cuadratura del plato

    OpenAIRE

    Ángeles Mora

    2012-01-01

    Una de las cosas que el Jurado del X Premio de Poesía Vicente Núñez destacó de este libro fue “su exquisito tratamiento del lenguaje”. Y desde luego lo es, es exquisito su tratamiento del lenguaje pero no porque utilice un lenguaje exquisito o excelso sino porque sabe arrancarle al lenguaje de todos los días, a las palabras sencillas, toda la carga poética de emoción e iluminación que llevan dentro. Mónica Doña nos dice que en su libro ha querido huir de un lirismo que muchas veces resulta fa...

  9. La persistencia del subalterno

    Directory of Open Access Journals (Sweden)

    John Beverley

    2002-10-01

    Full Text Available Este trabajo es el texto literal de una ponencia presentada en un panel sobre los estudios culturales latinoamericanos en el congreso de LASA en 2001 en Washington DC. Representa la posición desarrollada en el trabajo colectivo del llamado Grupo de Estudios Subalternos Latinoamericano, desde nuestra fundación en 1992 hasta la disolución del grupo en 2001, que sirve como pretexto introductorio para la ponencia. Los otros participantes en el panel eran Walter Mignolo, representando los estudios poscoloniales, Néstor García Canclini y John Kraniauskas, representando los estudios culturales, y Nelly Richard representando la llamada crítica cultural. El trabajo dialoga y debate con cada una de estas posiciones respectivamente desde el punto de vista específico de los estudios subalternos. Concluye con un llamado a una crítica del saber académico en sí.

  10. LA PERSISTENCIA DEL SUBALTERNO

    Directory of Open Access Journals (Sweden)

    John Beverley

    2002-01-01

    Full Text Available Este trabajo es el texto literal de una ponencia presentada en un panel sobre los estudios culturales latinoamericanos en el congreso de LASA en 2001 en Washington DC. Representa la posición desarrollada en el trabajo colectivo del llamado Grupo de Estudios Subalternos Latinoamericano, desde nuestra fundación en 1992 hasta la disolución del grupo en 2001, que sirve como pretexto introductorio para la ponencia. Los otros participantes en el panel eran Walter Mignolo, representando los estudios poscoloniales, Néstor García Canclini y John Kraniauskas, representando los estudios culturales, y Nelly Richard representando la llamada crítica cultural. El trabajo dialoga y debate con cada una de estas posiciones respectivamente desde el punto de vista específico de los estudios subalternos. Concluye con un llamado a una crítica del saber académico en sí.

  11. Enfermedad Diverticular del Colon

    OpenAIRE

    Gonzalo López Escobar

    1991-01-01

    Los divertículos del colon han sido reconocidos por varios observadores desde hace más de un siglo, pero en su mayor parte se trataba de casos aislados, hoy se la considera como la enfermedad del siglo XX, la de la era moderna y de los países industrializados y de avanzada tecnología (5,18,33).

    Según el diccionario de la Real Academia Española (11), divertículo, del latín, diverticulum, quiere decir desviación de un camino; y desde el punto de vista anatómico, apénd...

  12. En busca del concepto de gerencia del cuidado

    Directory of Open Access Journals (Sweden)

    Ligia Teresa Mora-Delgado

    2005-12-01

    Full Text Available Este articulo, presenta los conceptos de gerencia del cuidado de enfermería, desarrollado por las enfermeras profesionales que laboran en le Empresa social del estado Hospital Universitario Erasmo Meoz de las Ciudad de Cúcuta, desde su desempeño en la asistencia, administración y docencia. Se pretende además precisar los elementos gerenciales, sociales, humanísticos y éticos que deben hacer parte del concepto de gerencia del cuidado.

  13. EL PALACIO DEL MARQUÉS DEL ARCO: LA MADUREZ DEL PLATERESCO SEGOVIANO

    OpenAIRE

    Rodríguez de Antonio, Francisco de Paula

    2011-01-01

    En las postrimerías del siglo XV y durante el primer tercio del siglo XVI se produce en Segovia un proceso de transformación socioeconómico que culmina en un modelo social nuevo, más complejo, que adopta un nuevo lenguaje arquitectónico. El palacio del Marqués del Arco ejemplifica de manera singular el empleo de este nuevo lenguaje. El análisis del palacio incide en las particularidades urbanas, las alteraciones tipológicas respecto de otros modelos, el estudio estereotómico del patio; aunque...

  14. La Esencia del marketing

    OpenAIRE

    López-Pinto Ruíz, Bernardo

    2001-01-01

    Una de las finalidades más importantes de toda empresa es el beneficio. En la actualidad, el modo de conseguir más beneficio ya no es únicamente "incrementar el volumen de ventas", sino que la finalidad del beneficio se persigue a través de la satisfacción del cliente, mediante las herramientas de que dispone la dirección comercial, planificando un marketing adecuado al mercado en el que se desea incidir. Este trabajo pretende dar a conocer de forma generalizada y sintética los principales as...

  15. Desarrollo Integral del Escolar

    OpenAIRE

    Cañas Giraldo, Camilo Augusto

    2014-01-01

    La pediatría comprende cinco grupos de edades cuyos patrones de crecimiento, requerimientos nutricionales, comportamientos biológicos, y sobretodo comportamiento psicoafectivo, son diferentes. En la Carta de la Salud de febrero de 2013, la Dra. Patricia Montes había explicado el desarrollo del niño pre-escolar. En esta ocasión la Carta de la Salud versará sobre el desarrollo del niño escolar. Esta etapa se caracteriza por la creatividad y la ingeniosidad, pues p...

  16. Plasticidad del sistema nervioso

    Directory of Open Access Journals (Sweden)

    L. M. Garcia-Segura

    1976-06-01

    Full Text Available En este trabajo se revisan los conocimientos más recientes sobre el fenómeno de la plasticidad del sistéma nervioso, tanto a nivel morfológico como a nivel fisiológico y molecular. Se estudian los cambios morfólogicos y fisiológicos de las neuronas frente a la experiencia. Tambien se considera la adaptación molecular del sistéma nervioso a la información que recibe como la base de todo tipo de plasticidad.

  17. Infecciones del tracto urinario

    OpenAIRE

    Andrés Wurgaft, K.

    2010-01-01

    La infección del tracto urinario (ITU), con sus múltiples presentaciones clínicas, está entre las enfermedades infecciosas más frecuentes, tanto en pacientes ambulatorios como hospitalizados. El uso del examen de orina completa y de urocultivo debe ser racional. La bacteriuria asintomática no debe ser buscada ni tratada, en parte porque esto favorece el desarrollo de bacterias resistentes a antibióticos. Distintos cuadros clínicos requieren de distintas duraciones de terapia antibiótica, y ta...

  18. Lo siniestro del enigma.

    OpenAIRE

    Victoria Eugenia Diaz.

    1999-01-01

    En "El nacimiento de la filosofía griega", Giorgio Colli nos muestra una faceta tenebrosa del enigma. El dios Apolo, de naturaleza ilimitada, insondable, caprichosa, plantea al hombre enigmas que lo enfrentan con el sufrimiento y con la muerte. Allí, Edipo se confronta con enigmas enviados por el dios en los que se pone en juego su propia existencia. Tiempo después, en el transcurrir del siglo XX, reaparece una nueva forma de este dios arbitrario y arrogante: el desaparecedor de personas, ese...

  19. El malestar del pensamiento

    OpenAIRE

    José Luis Pardo

    2006-01-01

    El presente texto es una reflexión en torno a la crisis de la representación utilizando como clave hermenéutica el proyecto político de la modernidad tardoindustrial: el llamado "estado de bienestar" ( Welfare State), que en la era globalizada muestra su obsolescencia como renuncia a la contabilidad del sufrimiento, pero cuyo continuado simulacro ha generado un paradojal "estado de malestar". A partir de esta propuesta se desarrolla un paralelo entre Las Meninas de Velázquez y la portada del ...

  20. Storia del pensiero matematico

    CERN Document Server

    Kline, Morris

    1999-01-01

    Costruita con l'intento di presentare le idee oltre ai protagonisti della matematica, questa storia ha il duplice pregio dell'esaustività e della chiarezza. Essa prevede infatti vari livelli di lettura: lo specialista vi trova una messe di dati, fonti e spunti di ricerca, mentre lo studente ha a disposizione un formidabile strumento di consultazione e sintesi. L'arco temporale coperto è vasto: dalla Mesopotamia a Euclide, da Fibonacci all'invenzione del calcolo infinitesimale, da Gauss a Poincare, con un'appendice dedicata agli sviluppi piu recenti scritta appositamente per la prima edizione italiana del 1991, nei «Manuali» Einaudi.

  1. Voz del anciano

    OpenAIRE

    Sarrasqueta-Sáenz, L. (Laura); Marques-Girbau, M. (Margarita); Ruba, D. (David); Fernandez-Gonzalez, S. (Secundino)

    2006-01-01

    La vejez es en sí un fenómeno biológico que no implica necesariamente una enfermedad. Los fenómenos biológicos del envejecimiento se inician en edades muy tempranas y tiene la capacidad de modificarse, preveerse y compensarse. La educación y la preparación para posibles deterioros debe de ser contemplada desde un plano preventivo. En el ser humano la aparición del lenguaje y su vehículo habitual, la voz; representó la posibilidad de aumentar su longevidad. El deterioro...

  2. Los chicos del Mundial

    OpenAIRE

    Gómez, Reynaldo Claudio

    2008-01-01

    Quisiera apelar al lector, sobre todo al joven lector, para que admita una licencia en este artículo, y también a los editores: prefiero elegir un tono personal para refe- renciar el Mundial 78, más que avanzar desde un criterio académico o científico. Para los que atravesamos los 40 de edad, el Mundial 78 constituye uno de esos hechos que la literatura y la costumbre gustan de denominar como "significativo". También se ocupan del término, con el pasar del tiempo, la dignidad y la m...

  3. Panorama histórico del libro ilustrado y el libro-álbum en la literatura infantil colombiana

    OpenAIRE

    Pardo Chacón, Zully

    2014-01-01

    El desarrollo del libro ilustrado para niños en Colombiaes el tema principal del presente artículo, en el que seexponen, de manera muy general, el auge y el desarrollode la literatura infantil colombiana haciendo énfasisen la década de 1980 y en algunas de las coleccionesnacionales de libro ilustrado y libro-álbum. Se exponenlos trabajos precursores de este género y las editorialesque marcaron una pauta, así como un panorama generalde la situación actual.

  4. Ag-functionalized carbon molecular-sieve membranes based on polyelectrolyte/polyimide blend precursors

    NARCIS (Netherlands)

    Barsema, J.N.; van der Vegt, N.F.A.; Koops, G.H.; Wessling, Matthias

    2005-01-01

    We prepared dense flat-sheet Ag-functionalized carbon molecular-sieve (CMS) membranes from blends of P84 co-polyimide and a sulfonated poly(ether ether ketone) with a Ag+ counterion (AgSPEEK). These blends offer the possibility of producing new functionalized precursor structures, which were

  5. Enrichment of skin-derived neural precursor cells from dermal cell populations by altering culture conditions.

    Science.gov (United States)

    Bayati, Vahid; Gazor, Rohoullah; Nejatbakhsh, Reza; Negad Dehbashi, Fereshteh

    2016-01-01

    As stem cells play a critical role in tissue repair, their manipulation for being applied in regenerative medicine is of great importance. Skin-derived precursors (SKPs) may be good candidates for use in cell-based therapy as the only neural stem cells which can be isolated from an accessible tissue, skin. Herein, we presented a simple protocol to enrich neural SKPs by monolayer adherent cultivation to prove the efficacy of this method. To enrich neural SKPs from dermal cell populations, we have found that a monolayer adherent cultivation helps to increase the numbers of neural precursor cells. Indeed, we have cultured dermal cells as monolayer under serum-supplemented (control) and serum-supplemented culture, followed by serum free cultivation (test) and compared. Finally, protein markers of SKPs were assessed and compared in both experimental groups and differentiation potential was evaluated in enriched culture. The cells of enriched culture concurrently expressed fibronectin, vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors as compared to control culture. In addition, they possessed a multipotential capacity to differentiate into neurogenic, glial, adipogenic, osteogenic and skeletal myogenic cell lineages. It was concluded that serum-free adherent culture reinforced by growth factors have been shown to be effective on proliferation of skin-derived neural precursor cells (skin-NPCs) and drive their selective and rapid expansion.

  6. Artemisinin and sesquiterpene precursors in dead and green leaves of Artemisia annua L. crops

    NARCIS (Netherlands)

    Lommen, W.J.M.; Elzinga, S.; Verstappen, F.W.A.; Bouwmeester, H.J.

    2007-01-01

    This paper analyses the accumulation and concentrations of the antimalarial artemisinin in green and dead leaves of Artemisia annua crops in two field experiments. Concentration differences were analysed as being determined by (a) the total production of artemisinin plus its upstream precursors

  7. In vivo MRI evaluation of anabolic steroid precursor growth effects in a guinea pig model

    Science.gov (United States)

    Tang, Haiying; Vasselli, Joseph R.; Tong, Christopher; Heymsfield, Steven B.; Wu, Ed X.

    2015-01-01

    Anabolic steroids are widely used to increase skeletal muscle (SM) mass and improve physical performance. Some dietary supplements also include potent steroid precursors or active steroid analogs such as nandrolone. Our previous study reported the anabolic steroid effects on SM in a castrated guinea pig model with SM measured using a highly quantitative magnetic resonance imaging (MRI) protocol. The aim of the current study was to apply this animal model and in vivo MRI protocol to evaluate the growth effects of four widely used over-the-counter testosterone and nandrolone precursors: 4-androstene-3 17-dione (androstenedione), 4-androstene-3β 17β-diol (4-androsdiol), 19-nor-4-androstene-3β-17β-diol (bolandiol) and 19-nor-4-androstene-3 17-dione (19-norandrostenedione). The results showed that providing precursor to castrated male guinea pigs led to plasma steroid levels sufficient to maintain normal SM growth. The anabolic growth effects of these specific precursors on individual and total muscle volumes, sexual organs, and total adipose tissue over a 10-week treatment period, in comparison with those in the respective positive control testosterone and nandrolone groups, were documented quantitatively by MRI. PMID:19463691

  8. Solid state photochemistry. Subpanel A-2(a): Design of molecular precursors for electronic materials

    Energy Technology Data Exchange (ETDEWEB)

    Wells, R.L. [Duke Univ., Durham, NC (United States)

    1996-09-01

    Recent achievements of synthetic chemistry in the field of electronic materials are presented in three categories; viz, precursor design for improved processing, new chemistry for selective growth, and new growth techniques. This is followed by a discussion of challenges and opportunities in two general areas designated as composition and structure, and growth and processing.

  9. Structural and magnetic properties of nanocrystalline FeNiMioB precursor

    NARCIS (Netherlands)

    Vojtanik, P; Matejko, R; Varga, R; Ocelik, Vaclav; Baryakhtar, VG

    2001-01-01

    The magnetic and structural properties of amorphous Fe40Ni39Mo4B18 alloy which is a precursor of new nanocrystalline material have been investigated. Differential scanning calorimetry (DSC) and the temperature dependence of resistivity were used to determine the structural stability and the

  10. A second pathway to degrade pyrimidine nucleic acid precursors in eukaryotes

    DEFF Research Database (Denmark)

    Andersen, Gorm; Bjornberg, Olof; Polakova, Silvia

    2008-01-01

    Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces kluyv...... of the eukaryotic or prokaryotic genes involved in pyrimidine degradation described to date....

  11. Increased Soluble EGF after Ischemis is Accompanied by a Decrease in Membrane-Associated Precursors

    Science.gov (United States)

    1993-01-01

    1761. 1949. release of biologically active EGF from its membrane- i!i, Jorgensen. U.. E. Nexo , and S. S. Poulsen. Thv- niumnbru•nt, bound precursors...S. S. Poulsen, and E. Nexo . eral nephrectomy (21). The levels of mRNA for HGF as The urinaryv excrewi,,n of epidermal grn,,h tac or hnei . raTa, well

  12. Copper(II) complex as a precursor for formation of cyano-bridged ...

    Indian Academy of Sciences (India)

    chemsci

    Copper(II) complex as a precursor for formation of cyano-bridged pentanuclear Fe. III. -Cu. II bimetallic assembly: Synthesis, characterization, crystal structure and antibacterial ... Single-crystal X-ray analysis indicated that 2 crystallized in the monoclinic system with ..... maximum absorption band at 431nm was assigned to.

  13. Characterization of Porcine Ventral Mesencephalic Precursor Cells following Long-Term Propagation in 3D Culture

    Directory of Open Access Journals (Sweden)

    Pia S. Jensen

    2012-01-01

    Full Text Available The potential use of predifferentiated neural precursor cells for treatment of a neurological disorder like Parkinson’s disease combines stem cell research with previous experimental and clinical transplantation of developing dopaminergic neurons. One current obstacle is, however, the lack of ability to generate dopaminergic neurons after long-term in vitro propagation of the cells. The domestic pig is considered a useful nonprimate large animal model in neuroscience, because of a better resemblance of the larger gyrencephalic pig brain to the human brain than the commonly used brains of smaller rodents. In the present study, porcine embryonic (28–30 days, ventral mesencephalic precursor cells were isolated and propagated as free-floating neural tissue spheres in medium containing epidermal growth factor and fibroblast growth factor 2. For passaging, the tissue spheres were cut into quarters, avoiding mechanical or enzymatic dissociation in order to minimize cellular trauma and preserve intercellular contacts. Spheres were propagated for up to 237 days with analysis of cellular content and differentiation at various time points. Our study provides the first demonstration that porcine ventral mesencephalic precursor cells can be long-term propagated as neural tissue spheres, thereby providing an experimental 3D in vitro model for studies of neural precursor cells, their niche, and differentiation capacity.

  14. A two-step genetic study on quantitative precursors of coronary ...

    Indian Academy of Sciences (India)

    A two-step genetic study on quantitative precursors of coronary artery disease in a homogeneous Indian population: Case–control association discovery and validation by transmission-disequilibrium test. SANJUKTA MALLIK and PARTHA P MAJUMDER http://www.ias.ac.in/jbiosci. (a). J. Biosci. 36(5), December 2011, ...

  15. Revealing the Formation of Copper Nanoparticles from a Homogeneous Solid Precursor by Electron Microscopy

    NARCIS (Netherlands)

    van den Berg, Roy; Elkjaer, Christian F; Gommes, Cedric J; Chorkendorff, Ib; Sehested, Jens; de Jongh, Petra E; de Jong, Krijn P; Helveg, Stig

    2016-01-01

    The understanding of processes leading to the formation of nanometer-sized particles is important for tailoring of their size, shape and location. The growth mechanisms and kinetics of nanoparticles from solid precursors are, however, often poorly described. Here we employ transmission electron

  16. Methods for conversion of lignocellulosic-derived products to transportation fuel precursors

    Science.gov (United States)

    Lilga, Michael A.; Padmaperuma, Asanga B.

    2017-10-03

    Methods are disclosed for converting a biomass-derived product containing levulinic acid and/or gamma-valerolactone to a transportation fuel precursor product containing diesel like hydrocarbons. These methods are expected to produce fuel products at a reduced cost relative to conventional approaches.

  17. In vitro generation of motor neuron precursors from mouse embryonic stem cells using mesoporous nanoparticles

    DEFF Research Database (Denmark)

    Garcia-Bennett, Alfonso E; König, Niclas; Abrahamsson, Ninnie

    2014-01-01

    Aim: Stem cell-derived motor neurons (MNs) are utilized to develop replacement strategies for spinal cord disorders. Differentiation of embryonic stem cells into MN precursors involves factors and their repeated administration. We investigated if delivery of factors loaded into mesoporous...

  18. Precursor of pion condensation: The softening of the quasi-elastic peak

    Science.gov (United States)

    Alberico, W. M.; Ericson, M.; Molinari, A.

    1980-05-01

    The phase transition of pion condensation is heralded in the disordered phase by an increase in the life time of the fluctuations for the staggered magnetization. This precursor phenomenon entails, in ordinary nuclei, a showing down of the nuclear quasi-elastic response when observed with spin-sensitive probes. Permanent address: Istituto di Fisica Teorica dell'Università di Torino, Turin, Italy.

  19. Accelerated evolution of the pituitary adenylate cyclase-activating polypeptide precursor gene during human origin

    DEFF Research Database (Denmark)

    Wang, Yin-Qiu; Qian, Ya-Ping; Yang, Su

    2005-01-01

    a strong functional constraint during the course of evolution. However, through comparative sequence analysis, we demonstrated that the PACAP precursor gene underwent an accelerated evolution in the human lineage since the divergence from chimpanzees, and the amino acid substitution rate in humans...

  20. Demonstration of 20 pharmaceuticals and personal care products (PPCPs) as nitrosamine precursors during chloramine disinfection.

    Science.gov (United States)

    Shen, Ruqiao; Andrews, Susan A

    2011-01-01

    The worldwide detection of pharmaceuticals and personal care products (PPCPs) in the aquatic environment and drinking water has been a cause for concern in recent years. The possibility for concurrent formation of nitrosamine DBPs (disinfection by-products) during chloramine disinfection has become another significant concern for delivered drinking water quality because of their potent carcinogenicity. This study demonstrates that a group of PPCPs containing amine groups can serve as nitrosamine precursors during chloramine disinfection. Molar yields higher than 1% are observed for eight pharmaceuticals, with ranitidine showing the strongest potential to form N-nitrosodimethylamine (NDMA). The molar conversion increases with the Cl(2):N mass ratio, suggesting that dichloramine is relevant to the formation of NDMA from these precursors. Although the trace level of PPCPs in the environment suggests that they may not account for the majority of nitrosamine precursors during the disinfection process, this study demonstrates a connection between the transformation of PPCPs and the formation of nitrosamines during chloramine disinfection. This both expands the pool of potential nitrosamine precursors, and provides a possible link between the presence of trace levels of certain PPCPs in drinking water sources and potential adverse health effects. Copyright © 2010 Elsevier Ltd. All rights reserved.