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Sample records for estudio molecular del

  1. Estudio del CH interestelar

    NASA Astrophysics Data System (ADS)

    Olano, C.; Lemarchand, G.; Sanz, A. J.; Bava, J. A.

    El objetivo principal de este proyecto consiste en el estudio de la distribución y abundancia del CH en nubes interestelares a través de la observación de las líneas hiperfinas del CH en 3,3 GHz. El CH es una molécula de amplia distribución en el espacio interestelar y una de las pocas especies que han sido observadas tanto con técnicas de radio como ópticas. Desde el punto de vista tecnológico se ha desarrollado un cabezal de receptor que permitirá la realización de observaciones polarimétricas en la frecuencia de 3,3 GHz, con una temperatura del sistema de 60 K y un ancho de banda de 140 MHz, y que será instalado en el foco primario de la antena parabólica del IAR. El cabezal del receptor es capaz de detectar señales polarizadas, separando las componentes de polarización circular derecha e izquierda. Para tal fin el cabezal consta de dos ramas receptoras que amplificarán la señal y la trasladarán a una frecuencia más baja (frecuencia intermedia), permitiendo de esa forma un mejor transporte de la señal a la sala de control para su posterior procesamiento. El receptor además de tener características polarimétricas, podrá ser usado en el continuo y en la línea, utilizando las ventajas observacionales y de procesamiento de señal que actualmente posee el IAR.

  2. Estudio multifrecuencia del flujo bipolar-molecular asociado con la proto-estrella VLA 1623

    NASA Astrophysics Data System (ADS)

    Artur de la Villarmois, E.; Merlo, D. C.; Gómez, M.

    In this work; we present a multi-wavelength study of the bipolar molecular outflow associated with the VLA 1623 proto-star (age 10 yrs). We analyze images obtained by Spitzer as well as other images from the literature. We identify 32 H (2.12 m) emission knots and 25 objects predominantly emitting in the [4.5] m band; usually known as EGOs (Extended Green Objects). Seven of these emissions are new EGO candidates; five of which have 2.12 m counter-parts. We compare the morphology of the emissions at 2.12 m and [4.5] m with the bipolar molecular outflow; finding an excellent agreement. The emissions are quasi-regularly spaced. We determine a dynamical time of 194.3 yrs between consecutive knots; which agrees with the lapse of time between eruptive FU Orionis events. This suggests that events of this type experimented by the central source might be the cause of the intermittency in the detected emissions. FULL TEXT IN SPANISH

  3. Estudio del sistema simbiótico AR Pavonis

    NASA Astrophysics Data System (ADS)

    Quiroga, C.; Brandi, E.; Ferrer, O.; García, L.; Barbá, R.

    Se presenta un estudio espectroscópico y polarimétrico de la binaria eclipsante AR Pavonis a partir de observaciones obtenidas con el telescopio de 2.15 m. del CASLEO (San Juan). El estudio de la naturaleza del sistema se realizó a través del análisis de algunos espectros reunidos entre los años 1990 y 1995 y de datos polarimétricos correspondientes al intervalo 1995 y 1997. El análisis espectroscópico indica que AR Pav está compuesta por una gigante roja M3.7 y una componente caliente compacta, con una temperatura mayor a 90000 K y una luminosidad del orden de 500Lsolar. A lo largo del período orbital, las variaciones observadas en flujo y en velocidades radiales, reflejan que las emisiones permitidas se forman en una región que rodea la componente caliente. El estudio de la polarización lineal de AR Pav indica que además de una componente interestelar, existe una componente intrínseca del sistema que varía temporalmente y con la longitud de onda de la luz polarizada. El distinto comportamiento del grado de polarización y del ángulo de posición observado en fases diferentes, sugiere que distintos mecanismos pueden estar actuando, dependiendo de la región de scattering observado a lo largo de la línea de la visual.

  4. Estudio multifrecuencia del medio interestelar cercano a HD 192281

    NASA Astrophysics Data System (ADS)

    Arnal, E. M.; Cappa, C.; Cichowolski, S.; Pineault, S.; St-Louis, N.

    Una de las causas que modifica la estructura y dinámica del medio interestelar es la acción que los vientos de las estrellas de gran masa ejercen sobre el mismo. En este trabajo, mediante el uso de datos interferométricos obtenidos en la banda de radio en la transición de 21-cm del Hidrógeno neutro y de imágenes de la emisión de continuo en las bandas de 408 y 1420 MHz, de imágenes HIRES del satélite IRAS en 60 y 100 micrones, y de observaciones de continuo obtenidas con radiotelescopios de disco simple en 2695, 4850 y 8350 MHz se ha realizado un estudio multifrecuencia de los efectos que los vientos estelares de HD 192281, una estrella de tipo espectral O5 Vn((f))p, han tenido sobre el medio interestelar que rodea a la misma.

  5. Estudio multifrecuencia del medio interestelar cercano a HD 192281

    NASA Astrophysics Data System (ADS)

    Arnal, E. M.; Cappa, C. E.; Cichowolski, S.; Pineault, S.; St-Louis, N.

    Una de las causas que modifica la estructura y dinámica del medio interestelar es la acción que los vientos de las estrellas de gran masa ejercen sobre el mismo. En este trabajo, mediante el uso de datos interferométricos obtenidos en la banda de radio en la transición de λ˜21-cm del hidrógeno neutro y de imágenes de la emisión de continuo en las bandas de 408 y 1420 MHz, de imágenes HIRES del satélite IRAS en 60 y 100μm, y de observaciones de continuo obtenidas con radiotelescopios de disco simple en 2695, 4850 y 8350 MHz se ha realizado un estudio multifrecuencia de los efectos que los vientos estelares de HD 192281, una estrella de tipo espectral O5,Vn((f))p, han tenido sobre el medio interestelar que rodea a la misma.

  6. Estudio teórico del CO2. Orbitales de valencia y del ``core''

    NASA Astrophysics Data System (ADS)

    Olalla Gutiérrez, E.

    Hemos calculado las intensidades de las transiciones E1 a los miembros de las series de Rydberg con origen en los orbitales ``no enlazantes'' del dióxido de carbono, especie de conocida relevancia atmosférica. Se han computado, asimismo, los continuos de fotoionización correspondientes a los distintos canales de ionización, representándolos como densidad espectral de fuerza de oscilador frente a la energía del fotón incidente; mostramos los resultados df/dE para la fotoionización total de esta especie en el intervalo 15-60 eV. Todos los cálculos se han llevado a cabo mediante la formulación Molecular del Método de los Orbitales de Defecto Cuántico, MQDO [1,2]. La calidad de los resultados que presentamos se ha evaluado en base a la comparación con los datos, tanto experimentales como teóricos, disponibles en la bibliografía. El acuerdo encontrado es altamente satisfactorio

  7. La implantacion del enfoque constructivista en el aula de ciencia: Estudio de caso multiple

    NASA Astrophysics Data System (ADS)

    Arroyo Betancourt, Luz I.

    Esta investigacion estudia la implantacion del enfoque constructivista en tres aulas de ciencia del contexto puertorriqueno. Se auscultaron las practicas educativas que utilizan maestras consideradas constructivistas y la correspondencia de sus practicas educativas con los elementos esenciales de la didactica que proponen los teoricos de los planteamientos constructivistas. Se ausculto, ademas, a que vision del enfoque constructivista responden las expresiones de las maestras acerca de su practica educativa y como compara con su quehacer, a la luz de los elementos esenciales de las visiones constructivistas piagetiana, social y radical. Se utilizo el diseno de estudio descriptivo de caso multiple. El estudio se baso en entrevistas a profundidad, revision de documentos y observacion no participativa a la sala de clases. El contexto fueron tres escuelas publicas de la Region Educativa de San Juan, una elemental, una intermedia y una superior. Los resultados confirmaron que la transicion hacia el enfoque constructivista es un proceso que toma tiempo, dedicacion y la participacion en adiestramientos y readiestramientos acerca del nuevo enfoque. Las maestras coinciden en la mayoria de las practicas educativas que utilizan para implantar el enfoque constructivista de ensenanza y difieren en algunas debido, probablemente, a que han tenido que adaptarlas a los correspondientes niveles de ensenanza: elemental, intermedio y superior. Dos de las maestras planifican por conceptos generadores, mientras que una de ellas planifica siguiendo la guia que recibe del Departamento de Educacion. Difieren ademas, en el enfasis que confieren al inquirir cientifico. Con relacion a la correspondencia entre la vision manifestada por las maestras a la luz de las visiones piagetiana, social y radical, aparentemente, las preguntas del protocolo de entrevistas no lograron evocar la informacion con suficiente profundidad, por lo que la investigadora tuvo que inferir las visiones de las

  8. Estudio multiespectral del remanente de supernova W 28

    NASA Astrophysics Data System (ADS)

    Dubner, G.; Velázquez, P.; Castelletti, G.

    Se presentan observaciones en continuo de radio con muy alta resolución angular y sensibilidad del remanente de supernova (RSN) W28. Las observaciones fueron realizadas con el interferómetro Very Large Array (Estados Unidos), en las configuraciones C y D, en 1415 y 324 MHz. Por la gran extensión de este remanente (diámetro ~ 1o), las observaciones en 1415 MHz se realizaron en modo mosaico, combinando 48 apuntamientos diferentes en una única imagen. En ambas frecuencias los datos se procesaron con el agregado de observaciones de menor resolución angular, a fin de recuperar información en todas las frecuencias espaciales y obtener estimaciones precisas de densidad de flujo. Las imágenes resultantes muestran por primera vez la presencia de extensiones con forma de arco, cuya naturaleza se investiga. Las observaciones en radio se comparan con una imagen óptica de W28, y con la emisión en rayos X, observada con el satélite ROSAT. Este remanente muestra una clara morfología híbrida, tipo cáscara en frecuencias de radio y de centro lleno en las bandas óptica y de rayos X blandos.

  9. Estudio ab initio del mecanismo de la reacción HSO + O3

    NASA Astrophysics Data System (ADS)

    Nebot Gil, I.

    La reacción entre el radical HSO y el ozono ha sido ampliamente estudiada desde el punto de vista experimental debido a la importancia que tiene el radical HSO en la oxidación de los compuestos de azufre reductores y a que puede contribuir a la producción de H2SO4 [1-4]. Se realizaron diversos estudios teóricos sobre la cinética de la reacción entre el radical HSO y el ozono. La reacción del HSO con el ozono presenta tres canales diferentes : HSO + O3 &rightarrow &HSO2 + O2 &rightarrow &HS + 2 O2 &rightarrow &SO + OH + O2 La controversia existente entre los grupos experimentales sobre cuál de las tres vías es la predominante, se ha resuelto mediante un estudio teórico de todas ellas utilizando métodos ab initio. La estructura de todos los reactivos, productos, intermedios y estados de transición ha sido optimizada a nivel ab initio utilizando los métodos UMP2 /6-31G** y QCISD/6-31G**.

  10. Study of the Local Horizon. (Spanish Title: Estudio del Horizonte Local.) Estudo do Horizonte Local

    NASA Astrophysics Data System (ADS)

    Ros, Rosa M.

    2009-12-01

    The study of the horizon is fundamental to easy the first observations of the students at any education center. A simple model, to be developed in each center, allows to easy the study and comprehension of the rudiments of astronomy. The constructed model is presented in turn as a simple equatorial clock, other models (horizontal and vertical) may be constructed starting from it. El estudio del horizonte es fundamental para poder facilitar las primeras observaciones de los alumnos en un centro educativo. Un simple modelo, que debe realizarse para cada centro, nos permite facilitar el estudio y la comprensión de los primeros rudimentos astronómicos. El modelo construido se presenta a su vez como un sencillo modelo de reloj ecuatorial y a partir de él se pueden construir otros modelos (horizontal y vertical). O estudo do horizonte é fundamental para facilitar as primeiras observações dos alunos num centro educativo. Um modelo simples, que deve ser feito para cada centro, permite facilitar o estudo e a compreensão dos primeiros rudimentos astronômicos. O modelo construído apresenta-se, por sua vez, como um modelo simples de relógio equatorial e a partir dele pode-se construir outros modelos (horizontal e vertical)

  11. Presentación del estudio “Links” de hombres que tienes sexo con hombres en Buenos Aires, Argentina

    PubMed Central

    Carballo-Diéguez, Alex; Ávila, María M; Balán, Iván C.; Marone, Rubén; Pando, María A.; Barreda, Victoria

    2011-01-01

    Resumen Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos (“teteras”), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA. PMID:25264397

  12. Presentación del estudio "Links" de hombres que tienes sexo con hombres en Buenos Aires, Argentina.

    PubMed

    Carballo-Diéguez, Alex; Avila, María M; Balán, Iván C; Marone, Rubén; Pando, María A; Barreda, Victoria

    2011-03-01

    Estudios previos en Buenos Aires reportaron altas prevalencias de HIV entre HSH, con valores que oscilan entre 9 y 14% durante casi 10 años de continuo testeo. El objetivo principal de este estudio fue la evaluación de factores relacionados al comportamiento de alto riesgo para transmisión del HIV entre HSH entre los que se incluyen el conocimiento y factores emocionales, socioculturales y ambientales. Por otro lado se realizó la estimación de prevalencia e incidencia de HIV utilizando RDS (Respondent Driven Sampling), así como la presencia de otras infecciones de transmisión sexual. Por último se evaluaron los hábitos de testeo para HIV indagando que factores facilitan o impiden su realización. El estudio constó de dos fases, en primer lugar una fase cualitativa y posteriormente una fase cuantitativa con una duración total de 4 años y medio. Durante la fase cualitativa se realizaron 44 entrevistas individuales en profundidad, 8 grupos focales y 10 observaciones etnográficas (hoteles, baños públicos ("teteras"), cines pornográficos, fiestas privadas, dark rooms y discotecas). Durante la fase cuantitativa del estudio se realizó el reclutamiento de 500 participantes que provinieron de la Ciudad Autónoma de Buenos Aires, así como del Gran Buenos Aires. El reclutamiento se comenzó con 16 participantes llamados semillas. Se realizó el diagnóstico de infección por HIV, hepatitis B y C (HBV y HCV), Treponema pallidum, Virus Papiloma Humano (HPV) y Chlamidias. La colaboración establecida entre los grupos de trabajo enfocados en áreas diversas posibilitó el abordaje conjunto de nuevas estrategias de investigación antes no exploradas en nuestro país. Los resultados más relevantes de esta investigación serán progresivamente publicados en sucesivos números de Actualizaciones en SIDA.

  13. El contexto de la familia y el vecindario en la salud de los ancianos del estudio EPESE hispano

    PubMed Central

    Reyes-Ortiz, Carlos A.; Camacho, María E.; Eschbach, Karl; Markides, Kyriakos S.

    2014-01-01

    RESUMEN En este artículo se discute el papel de la familia y el vecindario en la salud de los ancianos méjico-americanos del estudio EPESE (Established Populations for Epidemiologic Studies of the Elderly) hispano. La paradoja epidemiológica consiste en que, a pesar de estar en desventaja socioeconómica, los ancianos hispanos tienen mortalidad relativamente menor que los ancianos de raza blanca. Esto es especialmente cierto cuando el anciano vive en los vecindarios donde hay un porcentaje alto de méjico-americanos. La familia también juega un papel importante en estos ancianos al disminuir el riesgo de institucionalización o de morbilidad. Asimismo, el estrés originado en problemas económicos o al depender económicamente de la familia, habiendo inmigrado en edades tardías, puede sobrepasar la capacidad de amortiguamiento del estrés y afectar la salud del anciano méjico-americano. PMID:25190897

  14. Estudio del comportamiento tribologico y de las interacciones de superficie de nuevos nanofluidos ionicos

    NASA Astrophysics Data System (ADS)

    Espinosa Rodriguez, Tulia

    tribocorrosion processes. The formation of a coating layer on magnesium alloys from phosphonate imidazolium ionic liquids by immersion and by chronoamperometry has been described. The new coatings reduce the abrasive wear in the magnesium-aluminium alloy but they are not effective in the magnesium-zinc alloy, which prevent the formation of continuous coatings. Los liquidos ionicos son sales liquidas a temperatura ambiente o bajas temperaturas que presentan excelentes propiedades fisico-quimicas. En el presente trabajo se estudian como lubricantes en problemas tribologicos complejos como la lubricacion de metales contra si mismos, el desarrollo de lubricantes base agua y de nuevas superficies autolubricadas. Cuando no es posible reducir la friccion y desgaste mediante lubricacion, como en las aleaciones de magnesio, los liquidos ionicos se han estudiado como precursores de recubrimientos protectores. Se han determinado las interacciones superficiales y los procesos de corrosion sobre cobre y sobre acero con diferentes liquidos ionicos proticos y aproticos para desarrollar nuevos lubricantes y aditivos. En el contacto cobre/cobre, excepto el liquido ionico protico derivado del oleato, todos los liquidos ionicos estudiados presentan mejor comportamiento tribologico que el lubricante comercial Polialfaolefina 6. En el contacto acero/zafiro, los nuevos liquidos ionicos proticos son buenos lubricantes cuando se utilizan en estado puro, y, como aditivos en agua, generan peliculas adsorbidas sobre la superficie del metal reduciendo la friccion y el desgaste tras la evaporacion del agua. Para evitar el periodo de alta friccion inicial en presencia de agua, se han generado peliculas superficiales de liquido ionico sobre el acero en condiciones estaticas. El mejor comportamiento lubricante tanto en el contacto cobre/cobre como en el contacto acero/zafiro se obtiene para el liquido ionico protico derivado del anion adipato, con dos grupos carboxilicos. Las interacciones de los grupos

  15. Estudio del comportamiento acustico de recubrimientos de suelo derivados de la madera

    NASA Astrophysics Data System (ADS)

    Gadea Borrell, Jose Maria

    This work describes a study of the vibroacoustic behaviour of laminate flooring and is partly accomplished by means of an experimental method somewhat simpler than that normally used at the present time and partly by a hybrid FEM-FDTD numerical method that reproduces the proposed experiment. The experimental configuration records the sounds emitted by laminate floors when impacted and the numerical method allows the sound produced by the laminate floor to be determined before installation by previously reproducing its sound. The registers obtained from both methods are evaluated from the psychoacoustic perspective with the aim of determining the relevant parameters involved in their perception, and thus provide a method of distinguishing the effect of the different component materials on the sound produced by this type of floor covering. In the field of building acoustics, with which this work is involved, laminate flooring is seen as a good solution for deadening the noise of impacts. This question has now become important due to stricter building acoustic regulations (DB-HR Proteccion frente al ruido" del Codigo Tecnico de la Edificacion, CTE). Laminate floors possess the advantage that they can be installed over existing floor coverings. Their lightness, which adds little additional strain to structures, and the fact that they are easy to fit, make them an attractive solution at the present time and gives them promising prospects for the future. Of the different types available, synthetic laminate floors are now the most popular by far in almost all types of building and for this reason research is being carried out on the users' opinion of their quality and convenience. Among the factors that affect the latter quality is their acoustic behaviour as regards both the insulation of sound transmitted to neighbouring rooms and the sound reflected from the floor in the room in which it is installed. The conclusions reached in this work are related to the latter

  16. Estudio numerico y experimental del proceso de soldeo MIG sobre la aleacion 6063--T5 utilizando el metodo de Taguchi

    NASA Astrophysics Data System (ADS)

    Meseguer Valdenebro, Jose Luis

    improvement on mechanical properties in aluminum metal joint. Los procesos de soldadura por arco electrico representan unas de las tecnicas mas utilizadas en los procesos de fabricacion de componentes mecanicos en la industria moderna. Los procesos de soldeo por arco se han adaptado a las necesidades actuales, haciendose un modo de fabricacion flexible y versatil. Los resultados obtenidos numericamente en el proceso de soldadura son validados experimentalmente. Los principales metodos numericos mas empleados en la actualidad son tres, metodo por diferencias finitas, metodos por elementos finitos y metodo por volumenes finitos. El metodo numerico mas empleado para el modelado de uniones soldadas, es el metodo por elementos finitos, debido a que presenta una buena adaptacion a las condiciones geometricas y de contorno ademas de que existe una diversidad de programas comerciales que utilizan el metodo por elementos finitos como base de calculo. Este trabajo de investigacion presenta un estudio experimental de una union soldada mediante el proceso MIG de la aleacion de aluminio 6063-T5. El metodo numerico se valida experimentalmente aplicando el metodo de los elementos finitos con el programa de calculo ANSYS. Los resultados experimentales obtenidos son: las curvas de enfriamiento, el tiempo critico de enfriamiento t4/3, geometria del cordon, microdurezas obtenidas en la union soldada, zona afectada termicamente y metal base, dilucion del proceso, areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Los resultados numericos son: las curvas del ciclo termico, que representan tanto el calentamiento hasta alcanzar la temperatura maxima y un posterior enfriamiento. Se calculan el tiempo critico de enfriamiento t4/3, el rendimiento termico y se representa la geometria del cordon obtenida experimentalmente. La zona afectada termicamente se obtiene diferenciando las zonas que se encuentran a diferentes temperaturas, las areas criticas intersecadas entre las

  17. Estudio del Hidrógeno neutro en dirección al remanente de supernova W28

    NASA Astrophysics Data System (ADS)

    Dubner, G.; Velazquez, P.; Green, A.; Goss, W. M.; Reynoso, E.

    Se presenta un relevamiento del hidrógeno neutro alrededor del remanente de supernova W28 realizado con el radiotelescopio australiano de Parkes. Se analizan rasgos de emisión y absorción. Se muestra la existencia de estructuras anulares asociadas con el remanente. Se compara la distribución del hidrógeno neutro con la ubicación de máseres de OH detectados en la línea de 1720 MHz.

  18. Un nuevo estudio del cúmulo abierto Tr 14 en la región de Carina

    NASA Astrophysics Data System (ADS)

    García, B.; Malaroda, S.; Levato, H.; Morrell, N.

    Presentamos nuevos datos espectroscópicos de 9 objetos entre los miembros más brillantes de Tr 14. Hemos medido un total de 80 nuevos espectrogramas para contribuir a la determinación de la real naturaleza de estos objetos desde el punto de vista de la duplicidad. Del nuevo material debemos concluir que la mayoría de las estrellas en la muestra son simples. Sin embargo existen algunos objetos cuyo seguimiento debe continuar ya que no nos es posible efectuar conclusiones definitivas con el presente material.

  19. Incentivos para atraer y retener personal de salud de zonas rurales del Perú: un estudio cualitativo

    PubMed Central

    Huicho, Luis; Canseco, Francisco Díez; Lema, Claudia; Miranda, J. Jaime; Lescano, Andrés G.

    2014-01-01

    El objetivo fue identificar incentivos de atracción y retención en zonas rurales y distantes de Ayacucho, Perú. Fueron realizadas entrevistas en profundidad con 80 médicos, enfermeras, obstetras y técnicos (20 por grupo) de las zonas más pobres y con 11 funcionarios. No existen políticas sistemáticas de atracción y retención de personal de salud en Ayacucho. Los principales incentivos, en orden de importancia, fueron mejoras salariales, oportunidades de formación y capacitación, estabilidad laboral y nombramiento, mejoras en infraestructura y equipos, e incremento del personal. Se mencionaron también mejoras en la vivienda y alimentación, mayor cercanía con la familia y reconocimiento por el sistema de salud. Existen coincidencias y singularidades entre los distintos grupos sobre los incentivos clave para estimular el trabajo rural, que deben considerarse al diseñar políticas públicas. Las iniciativas del Estado deben comprender procesos rigurosos de monitoreo y evaluación, para asegurar que las mismas tengan el impacto deseado. PMID:22488318

  20. Asociación de la adherencia a la dieta mediterránea al inicio del embarazo y riesgo de gastrosquisis en la descendencia: un estudio de casos-controles

    PubMed Central

    Cánovas-Conesa, A.; Gomariz-Peñalver, V.; Sánchez-Sauco, M.F.; Vega, D.C. Jaimes; Ortega-García, J.A.; García, M.J. Aranda; Marín, J.L. Delgado; Ascanio, A. Trujillo; Hernández, F. López; Jimenez, J.I. Ruiz; de Paco Matallana, C.; Soldin, O.P.; Solís, M. Sánchez

    2016-01-01

    Resumen Objetivos El objetivo de este estudio fue estudiar la asociación de la adherencia a la dieta mediterránea materna al inicio del embarazo y el riesgo de gastrosquisis en la descendencia. Métodos Estudio de casos-control. 11 casos incidentes de gastrosquisis en la Región de Murcia de 2007 a 2012 y 34 controles concurrentes. Cuestionario validado de Frecuencia Alimentaria (CFA) sobre la dieta periconcepcional de 98 ítems realizado ‘cara a cara’ en el momento del diagnóstico. Factores confundidores: tabaquismo, expositión a cannabis/marihuana, edad materna y paterna, índice de masa corporal, ingresos económicos y nivel de estudios. Estudio descriptivo y regresión logística multivariable. Resultados Las madres de niños con gastrosquisis son más jóvenes (20,8 años; IC 95% 17,3–24,2) y su dieta tiene un menor aporte calórico, de grasas saturadas y monoinsaturadas y de proteínas que los controles. Odds Ratio (OR) en el modelo multivariable controlado por los factores confundidores: edad materna (años) 0,70 (IC95% 0,51–0,96); ácidos grasos monoinsaturados (oleico, g) 0,79 (IC95% 0,65–0,97) y consumo de vegetales (raciones/semana) 0,70 (IC95% 0,48–1,00). Conclusiones Una dieta materna rica en ácido oleico y productos vegetales podría contribuir a prevenir el riesgo de oclusión vascular de las arterias onfalomesentéricas, disminuyendo el riesgo de gastrosquisis. PMID:23833926

  1. Molecular Survey of Hepatitis C Virus in the Touristic City of Mar Del Plata, Argentina

    PubMed Central

    Culasso, Andrés C. A.; Elizalde, Mercedes; Campos, Rodolfo H.; Barbini, Luciana

    2012-01-01

    The global epidemiology of Hepatitis C Virus (HCV) may be roughly described by two groups of genotypes: the worldwide distributed ones (subtypes 1a, 1b, 2a and 3a, among others) and the endemic ones (subtypes 4a, 5a, 6a, among others). Epidemiological and population dynamic studies of the worldwide distributed genotypes have shown that subtypes 1a and 3a are common among intravenous drug users (IDUs) and that they are also in expansion in some countries. The molecular survey of HCV provides some clues about the epidemiological status of the infections in a local scale and the phylogenetic and demographic reconstruction analyses complement this study by inferring whether the infections of certain subtypes are in a steady state or expanding. Here, a molecular survey of the HCV variants that circulate in the touristic city of Mar del Plata (Buenos Aires, Argentina) was performed in samples obtained from 42 patients. The subtypes detected were 1a (32 patients), 3a (8 patients) and 1b (2 patients). The demographic history of subtype 1a inferred using the sequence data showed an exponential growth in the 1990′s. The period of viral expansion was delayed compared with that observed for the same genotype in other countries where the transmission was associated with IDUs. Also, the phylogeographic analysis of HCV-1a showed a statistically significant association between the location of the samples and the phylogeny, which may be the result of the local transmission of HCV in the city. The molecular analysis helped in the description of the complex epidemiological context of a touristic city, and pointed out that some sanitary measures should be taken in order to reduce the transmission of HCV (and maybe of HIV) among IDUs. PMID:23028605

  2. Molecular epidemiology and genetic diversity of hepatitis B virus in Mar del Plata city, Argentina.

    PubMed

    Barbini, Luciana; Elizalde, Mercedes; Torres, Carolina; Campos, Rodolfo

    2013-10-01

    The aim of this work was to describe the current molecular epidemiology and genetic diversity of HBV in Mar del Plata, an important Argentinean touristic city. The phylogenetic analysis of 29 HBV DNA positive serum samples showed that F1b was the predominant subgenotype (sgt, 62.1%), followed by sgt A2 (13.8%) and sgt F4, gt D and gt G (6.9% each). Among anti-HBc IgM positive samples, 75.0% were sgt F1b, followed by sgt F4 (12.5%), sgt A2 (6.25%) and sgt D (6.25%). Three recombinant full length genomes were found: two G/F1b (some of the first gt G detected in Argentina) and one F4/D2. The circulation of clinical important mutations in the city was described. Mutations at the HBsAg were detected in 34.5% of the analyzed samples, associated with laboratory diagnosis and antiviral treatment failures, immune escape and hepatocellular carcinoma. Most of the samples presented wild type BCP/PC sequences. Coalescence analysis for the most prevalent sgt F1b estimated that the diversification mainly occured during mid '90s and the tMRCA was estimated in 1987. Finally, the high presence of the autochthonous sgt F1b, associated with the anti-HBc IgM positive infection and its present-day diversification process, shows the strong impact of internal human migratory movements into the current population of Mar del Plata.

  3. Estudio fotométrico y espectroscópico de dos cúmulos abiertos jóvenes del disco con apariencia globular

    NASA Astrophysics Data System (ADS)

    Piatti, A. E.; Clariá, J. J.; Bica, E.

    Se presentan y discuten resultados obtenidos en el CASLEO y en el Observatorio de Las Campanas de dos cúmulos abiertos compactos con apariencia globular: Westerlund1 (BH197), ubicado en dirección hacia el centro galáctico, y Westerlund2. A partir de espectroscopía CCD integrada de ambos e imágenes CCD en las bandas VI obtenidas para el primero de ellos, se derivan sus parámetros fundamentales y se examinan sus apariencias estructurales. Se encuentra que Westerlund1 es un cúmulo joven (7 ± 3 millones de años), ubicado sobre el plano galáctico a 1.0 ± 0.4 kpc del sol, en una región caracterizada por una absorción excepcionalmente elevada (Av~=13.0 mag), en tanto que Westerlund2 es también un cúmulo joven (4-6 millones de años) ubicado sobre el plano, en una región afectada por una absorción menor (Av~=5.7 mag). Desde el punto de vista estructural, Westerlund 1 se presenta como uno de los pocos cúmulos abiertos jóvenes de la Galaxia con apariencia tipicamente globular, en contraste con los cúmulos azules de las Nubes de Magallanes en los cuales la apariencia globular constituye un fenómeno común. Westerlund2, aunque menos rico en estrellas, puede también ser incluído dentro de esta interesante clase de objetos.

  4. Del Xq23 in a mosaic Turner female: molecular and cytogenetic studies.

    PubMed

    Mesa-Cornejo, V M; García-Cruz, D; Monroy-Jaramillo, N; Vásquez, A I; Dávalos, N O; Galaviz, C; Kofman, S

    2001-01-01

    We report a Turner patient aged 22 years with a 45,X/46,X,del(X)(q23) karyotype. Late replication studies showed preferential inactivation of the deleted X chromosome; FISH studies with a probe for total human telomeres showed hybridisation signal in the telomeres on both the normal and the deleted X chromosomes. Microsatellite analysis in the proposita and her family permitted us to conclude to the maternal origin of the deleted X chromosome, and to detect using the marker DXS1106 (Xq22) a probable meiotic recombination event above the breakage point suggesting that the deletion occurred underneath this point. The mild Turner stigmata may be explained by the 45,X cell line, and the gonadal dysgenesis probably by a partial deletion of the gonadal dysgenesis region Xq13-q23 (excluding Xq22).

  5. Estudio teórico de moléculas de interés en Astrofísica: compuestos binarios policarbonados

    NASA Astrophysics Data System (ADS)

    Largo-Cabrerizo, A.

    Se han detectado en el espacio distintos compuestos binarios policarbonados (que se pueden formular como CnX), algunos de ellos con elementos de la primera fila del sistema periódico, pero también existen otros que contienen elementos de la segunda fila, como azufre o silicio. La información experimental sobre estos últimos compuestos es escasa, por lo que los estudios teóricos son especialmente valiosos en este campo. En esta comunicación presentaremos los avances mas recientes que sobre el tema ha realizado nuestro grupo. Incidiremos particularmente en dos aspectos. En primer lugar resumiremos los estudios en los que hemos intentado proporcionar información estructural sobre carburos metálicos formados por sodio, magnesio, aluminio o calcio, que pueda ser de ayuda a la hora de caracterizar estas moléculas en laboratorio como paso previo a su eventual detección en el espacio. Un aspecto importante dentro de este primer apartado es el análisis de las propiedades moleculares en función del tamaño del sistema (cuantificado en el numero de átomos de carbono) con el objeto de intentar sistematizar su estudio. En segundo lugar comentaremos brevemente algunos de los estudios realizados sobre posibles reacciones que pueden ser vías de síntesis de este tipo de compuestos en el medio interestelar.

  6. Predictive Value of Molecular Drug Resistance Testing of Mycobacterium tuberculosis Isolates in Valle del Cauca, Colombia

    PubMed Central

    García, Pamela K.; Nieto, Luisa Maria; van Soolingen, Dick

    2013-01-01

    Previous evaluations of the molecular GenoType tests have promoted their use to detect resistance to first- and second-line antituberculosis drugs in different geographical regions. However, there are known geographic variations in the mutations associated with drug resistance in Mycobacterium tuberculosis, and especially in South America, there is a paucity of information regarding the frequencies and types of mutations associated with resistance to first- and second-line antituberculosis drugs. We therefore evaluated the performance of the GenoType kits in this region by testing 228 M. tuberculosis isolates in Colombia, including 134 resistant and 94 pansusceptible strains. Overall, the sensitivity and specificity of the GenoType MTBDRplus test ranged from 92 to 96% and 97 to 100%, respectively; the agreement index was optimal (Cohen's kappa, >0.8). The sensitivity of the GenoType MTBDRsl test ranged from 84 to 100% and the specificity from 88 to 100%. The most common mutations were katG S315T1, rpoB S531L, embB M306V, gyrA D94G, and rrs A1401G. Our results reflect the utility of the GenoType tests in Colombia; however, as some discordance still exists between the conventional and molecular approaches in resistance testing, we adhere to the recommendation that the GenoType tests serve as early guides for therapy, followed by phenotypic drug susceptibility testing for all cases. PMID:23658272

  7. Clinical and molecular cytogenetic studies in ten patients with hematological malignancies characterized by t(20;21)(q11;q11) resulted from del(20q).

    PubMed

    Wu, Chunxiao; Zhang, Jun; Bai, Shuxiao; Yao, Jianxin; Qiu, Huiying; Xue, Yongquan; Chen, Suning; Wu, Yafang; Shen, Juan; Pan, Jinlan

    2016-10-01

    This study reports 10 patients with hematological malignances with t(20;21)(q11;q11) resulting from del(20q) (for example, der(20)del(20)(q11q13)t(20;21)(q11;q11) and der(21)t(20;21)(q11;q11)) and described their clinical features and the possible prognostic significance of this abnormality. The t(20;21)(q11;q11) was a rare but recurrent abnormality secondary to del(20q) besides i(20q-). The frequency of der(20)del(20)(q11q13)t(20;21)(q11;q11) among our patients with del(20q) was 2.4%. It was considered that the 20q deletion preceded translocation with chromosome 21. This abnormality is often cryptic, occurs predominantly in older men and is observed most often in myelodysplastic syndromes. Patients with this abnormality have an unfavorable prognosis, similar to patients with i(20q-). The molecular consequences of der(20)del(20)(q11q13)t(20;21)(q11;q11) may be different from patients with i(20q-). To the best of our knowledge this is the largest dataset published to date.

  8. Apoyo a Estudios Geodinamicos con GPS en Guatemala

    NASA Astrophysics Data System (ADS)

    Robles, V. R.

    2013-05-01

    El Instituto Geografico Nacional de Guatemala implemento 17 estaciones GNSS en el año 2009, como un proyecto de credito mixto de donacion de equipamiento del Gobierno de Suiza, el cual, este equipamiento de estaciones CORS GNSS es un sistema de recepción y transmisión de datos crudos GPS RInex que utiliza la tecnologia Spider Web de Leica, asi mismo este sistema esta sirviendo para el espablecimiento de un marco geodesico nacional de coordenadas geodesicas oficiales, el cual se calculan u obtienen las velocidades en tiempos temporales programados de las 17 Estaciones CORS. La infraestructura del marco geodesico de Guatemala esta sirviendo de base para las aplicaciones de estudios geodinamicos como el monitoreo de del desplazamiento de las placas tectonicas por medio de un estudio que se inicio en el año de 1999, llamado medicion con GPS el sistema de Fallas de los rios Polochic Motagua de Guatemala, tambien para un estudio que se implemento para deformación de corteza terrestre local en un Volcan Activo de Guatemala llamado Pacaya. Para el estudio de medicion con GPS en el sistema de falla de los Rios del polochic Motagua se implementaron 16 puntos para medir con GPS de dos frecuencias en el año de 1999, el cual, tres puntos son estaciones geodesicas CORS IGS llamados GUAT, ELEN y HUEH, despues en el año de 2003 se hizo otra medicion en un total de 20 puntos, que permitió calcular las velocidades de desplazamieinto de los puntos en mención, usando como referencia el modelo NUVEL 1A de DeMets de la placa de Norteamerica. Este estudio fue en cooperación internacional por la universidad de Nice de Francia y el IGNde Francia. Para el estudio del monitoreo con GPS del volcan activo de Guatemala, se implementaron cuatro puntos al rededor del volcan, el cual, se realizan cuatro mediciones al año, que permiten determinar axialmente la distancias entre los puntos, y rebisar estadisticamente cual es el comportamiento de las distancias en funcion del tiempo, si

  9. A Reappraising of Cosmography: the Interface Between Astronomical and Geographic Studies. (Breton Title: Releitura do Conceito de Cosmografia: a Interface Entre os Estudos Astronômicos e Geográficos.) Una Relectura del Concepto de Cosmografía: la Interfase Entre los Estudios Astronómicos y Geográficos

    NASA Astrophysics Data System (ADS)

    Azevedo Sobreira, Paulo Henrique

    2012-12-01

    The concept of "Cosmography" is in disuse since the 80s of the last century, but the astronomical themes previously discussed in the school subjects of Geography and Cosmography remain in current textbooks. The use of term "Cosmography" was rescued in this research, and the study of its re-signification prompted the appearance of the term Geographic Cosmography. The Geographic Cosmography is a field of studies of the Geography, whose set of knowledge and skills is predominantly scholar. It studies the interface between terrestrial and celestial knowledge, and assigns a geographic significance to them. It examines human and natural relationships with Sidereal Space and its consequences for society and nature. O conceito de "Cosmografia" está em desuso desde os anos 80 do século XX, mas os temas astronômicos anteriormente abordados nas disciplinas escolares de Cosmografia e de Geografia permanecem nos atuais livros didáticos. O uso do termo "Cosmografia" foi resgatado nesta pesquisa e o estudo de sua ressignificação proporcionou o surgimento do termo Cosmografia Geográfica. A Cosmografia Geográfica é um campo de estudos da Geografia, cujo conjunto de conhecimentos e habilidades é predominantemente escolar. Estuda a interface entre os conhecimentos terrestres e os celestes e lhes atribui significância geográfica. Analisa as relações humanas e naturais com o Espaço Sideral e suas consequências para a sociedade e a natureza.

    Aunque el concepto de "Cosmografía" no se usa desde la década de los '80 del siglo pasado, los temas astronómicos que se enseñaban anteriormente en las asignaturas escolares de Cosmografía y de Geografía permanecen en los actuales libros didácticos. El uso del término "Cosmografía" fue rescatado en esta investigación y el estudio de su resignificación proporcionó el surgimiento del término Cosmografía Geográfica. La Cosmografía Geográfica es un campo de estudio de la Geografía, donde

  10. [β-hydroxy-β-methylbutyrate as a dietary supplement (II): cell and molecular mechanism of action].

    PubMed

    Manjarrez-Montes-de-Oca, Rafael; Torres-Vaca, Mateo; González-Gallego, Javier; Alvear-Ordenes, Ildefonso

    2014-11-27

    Introducción: En los últimos años el -hidroxi--metilbutirato (HMB) ha sido foco de diversas investigaciones que le atribuyen un efecto sobre la disminución de la proteólisis muscular y un incremento de la masa muscular. Por tanto, se han realizado estudios centrados en los mecanismos celulares y moleculares responsables de dichos efectos. Objetivos: Los objetivos de la presente revisión son: conocer el metabolismo del HMB, así como su absorción y excreción; estudiar la posible toxicidad del HMB; e identificar los mecanismos celulares y moleculares de acción del HMB cuando se utiliza como suplemento nutricional. Métodos: Se utilizaron las bases de datos Web of Science, Pubmed y SportDiscus para realizar la búsqueda de artículos. Los resultados se dividieron en dos partes; en este artículo se presentan los resultados referentes a los mecanismos de acción del HMB. Resultados: No existen suficientes datos que apoyen que la ingesta de HMB incremente la síntesis de colesterol en el músculo. Es posible que existan efectos positivos en el metabolismo muscular a través de la vía mTOR y del sistema ubiquitin-proteasoma, aunque no se conoce su mecanismo de acción. Probablemente, el HMB eleva los niveles sanguíneos de hidroxibutirato y esto podría explicar sus principales efectos sobre la disminución de la proteólisis muscular. Conclusiones: De acuerdo a nuestros resultados, la posibilidad de justificar la acción del HMB a través de la vía del beta-hidroxibutirato abre una interesante línea de investigación para futuros estudios.

  11. Estudio dinámico de un potencial perturbador dependiente de dos parámetros

    NASA Astrophysics Data System (ADS)

    Miloni, O.; Brunini, A.

    El objeto del presente trabajo consiste en el estudio dinámico de un sistema dinámico caracterizado por la función hamiltoniana correspondiente a un satélite planetario perturbado por la acción del Sol y del achatamiento del planeta madre. Cuando dicha Hamiltoniana se promedia respecto de los términos de corto período, esta queda con dos grados de libertad, y su estudio puede ser realizado con las herramientas clásicas de la dinámica no-lineal. Se tratará de determinar regiones regulares y caóticas de movimiento. En el caso de estas últimas, es de particular interés la determinación de su orígen.

  12. Estudio de seeing en la zona del Cerro Champaqui (I)

    NASA Astrophysics Data System (ADS)

    Diaz, R. J.; Eikenberry, S.; Scott, J.; Levato, H.; Firpo, V.; Farina, C.; Piroddi, D.; Jamud, N.; Bosch, G.; Mudrik, A.; Guzzo, P.; Donoso, V.; Recabarren, P.; Seifer, E.

    We report the results of the most recent seeing feasibility study performed in the region of Cerro Champaqui (2800m) at the mountain range of Sierras Grandes at the Province of Cordoba. We also describe the high frequency DIMM device built for this and other seeing samplings obtained at the provinces of San Juan; San Luis and Cordoba. This work is part of a long term project started in 2006; in search of sites of very low turbulence and suited for near infrared telescopes with active and adaptive optics. Two of the sites have been monitored during a total of 46 nights distributed in six months of the period 2011-2012. The preliminary results suggest the existence of `sub-arcsecond' seeing conditions during extended periods of time in at least one location in the mountain range in the SW of Cordoba and NE of San Luis provinces. FULL TEXT IN SPANISH

  13. The R215W mutation in NBS1 impairs {gamma}-H2AX binding and affects DNA repair: molecular bases for the severe phenotype of 657del5/R215W Nijmegen breakage syndrome patients

    SciTech Connect

    Masi, Alessandra di Viganotti, Mara; Polticelli, Fabio; Ascenzi, Paolo; Tanzarella, Caterina; Antoccia, Antonio

    2008-05-09

    Nijmegen breakage syndrome (NBS) is a genetic disorder characterized by chromosomal instability and hypersensitivity to ionising radiation. Compound heterozygous 657del5/R215W NBS patients display a clinical phenotype more severe than the majority of NBS patients homozygous for the 657del5 mutation. The NBS1 protein, mutated in NBS patients, contains a FHA/BRCT domain necessary for the DNA-double strand break (DSB) damage response. Recently, a second BRCT domain has been identified, however, its role is still unknown. Here, we demonstrate that the R215W mutation in NBS1 impairs histone {gamma}-H2AX binding after induction of DNA damage, leading to a delay in DNA-DSB rejoining. Molecular modelling reveals that the 215 residue of NBS1 is located between the two BRCT domains, affecting their relative orientation that appears critical for {gamma}-H2AX binding. Present data represent the first evidence for the role of NBS1 tandem BRCT domains in {gamma}-H2AX recognition, and could explain the severe phenotype observed in 657del5/R215W NBS patients.

  14. Overdominance effect of the bovine ghrelin receptor (GHSR1a)-DelR242 locus on growth in Japanese Shorthorn weaner bulls: heterozygote advantage in bull selection and molecular mechanisms.

    PubMed

    Komatsu, Masanori; Sato, Yoichi; Negami, Tatsuki; Terada, Tohru; Sasaki, Osamu; Yasuda, Jumpei; Arakawa, Aisaku; Yoshida, Chikara; Takahashi, Hideaki; Malau-Aduli, Aduli E O; Suzuki, Keiichi; Shimizu, Kentaro

    2014-12-23

    Ghrelin and the ghrelin receptor (GHSR1a) are involved in growth hormone secretion, food intake, and several other important functions. Ghrelin acts on GHSR1a and induces signal transduction via the Gαq subunit. In our previous study, we identified the DelR242 (3R) allele, a truncated 3-arginine residue (3R) [major type: 4 arginine residues (4R)] of the third intracellular loop of GHSR1a, with a high frequency in Japanese Shorthorn bulls (0.43) but with a low frequency in other cattle breeds (0.00-0.09). To further investigate the reasons for the higher frequency of the 3R allele, we performed several experiments. In this study, we found a significant sex difference in the frequency of the 3R allele. Statistical analysis revealed a significant overdominance effect of the DelR242 locus on growth in Japanese Shorthorn weaner bulls. However, additive/dominance/overdominance effects of the 3R allele on carcass traits in adult steers and dams were not significant. The mode of the overdominance effect was estimated to be solely controlled by the single DelR242 locus without any other linked loci using linkage disequilibrium analysis in GHSR1a. These results indicated that 4R/3R heterozygotes had a selective advantage in weaner bulls because of their higher average daily gain than homozygotes. We discussed possible molecular mechanisms involved in the overdominance effect of the DelR242 locus on these traits in weaner bulls using a structural model of the complex consisting of a GHSR1a dimer and Gαq.

  15. Estudio de la fotoabsorción y fotoionización de la molécula de alta relevancia atmosférica no a través de los estados Rydberg con la metodología MQDO

    NASA Astrophysics Data System (ADS)

    Bustos, E.; Velasco, A. M.; Martín, I.; Lavín, C.

    Los procesos de fotoionización son de una importancia fundamental [1] y encuentran aplicación en un gran número de contextos científicos: Astrofísica [2], química de las radiaciones, biología. Los investigadores de dichos campos, necesitan de valores de fiables de secciones eficaces para la fotoionización parcial, la Fotoabsorción, así como para los procesos de fotofragmentación en amplios intervalos espectrales, particularmente en estudios de modelización [3-5]. En este trabajo se ha centrado la atención sobre el oxido nítrico, que se ha considerado apropiado y relevante por varios motivos: por el trascendental papel que representa en la física y química de la alta atmosfera [6], aparte de por estar íntimamente relacionado con los problemas de contaminación. Los procesos de recombinación disociativa [7] del NO, donde los estados Rydberg se encuentran directamente implicados, son relevantes, por ejemplo, en las regiones E y F de la ionosfera [7]. En este trabajo se estudia la fotoionización del NO desde el estado fundamental con la versión molecular del método del orbital de defecto cuántico (MQDO). Para ello se calcula el diferencial de las fuerzas de oscilador parciales que constituyen los canales de fotoionización del NO desde el estado fundamental. La continuidad del diferencial de fuerza de oscilador calculada a través del umbral de fotoionización, esto es, en las regiones del espectro discreta y del continua, se adopta como criterio de calidad la escasez de datos comparativos [8].

  16. Macrobenthos and multi-molecular markers as indicators of environmental contamination in a South American port (Mar del Plata, Southwest Atlantic).

    PubMed

    Albano, Mariano J; da Cunha Lana, Paulo; Bremec, Claudia; Elías, Rodolfo; Martins, César C; Venturini, Natalia; Muniz, Pablo; Rivero, Silvia; Vallarino, Eduardo A; Obenat, Sandra

    2013-08-15

    We evaluated benthic habitat quality along a presumed contamination gradient in the Mar del Plata port (Southwestern Atlantic) by coupling biological and chemical proxies in a multidisciplinary approach. Organic matter and photosynthetic pigment contents were higher in silty-clay bottoms of the inner port sites. Levels of all fecal steroids decreased from the inner sites to the port inlet. High concentrations of coprostanol in the inner sites seemed to derive from a permanent population of sea lions rather than from sewage outfalls due to coprostanol/epicoprostanol ratio (IV) values <2.5. PAHs levels were also higher in the inner sector, related to both biomass combustion and petroleum combustion associated to local marine traffic. High disturbance and low ecological status were reflected in low benthic diversity and high AMBI values in the inner sites.

  17. Estudio del hidrógeno neutro alrededor del remanente de la supernova de Tycho

    NASA Astrophysics Data System (ADS)

    Reynoso, E. M.; Velázquez, P. F.; Dubner, G.

    With the aim of studying the interstellar gas around Tycho's supernova remnant (SNR), we have analyzed HI 21 cm high resolution data. The high resolution image reveals that this SNR is placed inside a hollowed structure, being the highest density region closest to the NE edge of the remnant. This neutral gas concentration would explain the Balmer emission associated with this SNR observed in the optical range (Smith et al. 1991, ApJ 375, 652). The HI density gradient observed in the surrounding of this SNR does not account for the different expansion rates observed along the shell (Reynoso et al. 1997, ApJ 491, in press). This fact would be suggestive that those variations are intrinsic to the explosion and that the influence of the ambient medium is still not important on the dynamical evolution of the schock front, as expected for young SNRs. We have detected HI structures at higher velocities, whose connection with this SNR is uncertain

  18. Molecular characterization of a patient with an interstitial 1q deletion [del(1)(q24.1q25.3)] and distinctive skeletal abnormalities.

    PubMed

    Descartes, Maria; Hain, Julie Zenger; Conklin, Michael; Franklin, Judy; Mikhail, Fady M; Lachman, Ralph S; Nolet, Serge; Messiaen, Ludwine M

    2008-11-15

    Here we report on a patient with an interstitial deletion on the long(q) arm of chromosome 1 who presents with a unique constellation of anomalies including brachydactyly type E, Müllerian agenesis, growth hormone deficiency, as well as other abnormalities. We present the clinical details of this patient's presentation, the skeletal findings, and provide characterization of the deletion at the molecular level. We postulate that these skeletal anomalies are distinctive to 1q deletions involving the 1q24q25 region.

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

    NASA Astrophysics Data System (ADS)

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

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

  20. Delineation of the dup5q phenotype by molecular cytogenetic analysis in a patient with dup5q/del 5p (cri du chat).

    PubMed

    Levy, Brynn; Dunn, Teresa M; Kern, Jeffrey H; Hirschhorn, Kurt; Kardon, Nataline B

    2002-03-15

    An infant girl presented with multiple congenital abnormalities and a distinctive mewing cry. Her karyotype was 46,XX,add5p. Chromosome analysis on the mother revealed an apparently balanced pericentric inversion of chromosome 5, with the precise position of the breakpoints not clearly discernable by GTG banding, 46,XX,inv(5)(p15.2/3?q35.1?). Fluorescence in situ hybridization (FISH) studies using a commercial cri du chat probe (D5S721,D5S23) revealed signals on both the normal and derivative chromosomes. Telomeric probes specific for 5p and 5q were used to confirm the pericentric inversion in the mother and demonstrated the loss of the terminal 5p region and a duplication of the terminal 5q region in the proband. The imbalance on chromosome 5 in the patient was further defined using comparative genomic hybridization (CGH), which revealed a loss of material from 5p15.3 --> pter and a gain of 5q34 --> qter. The presence of the cat-like cry appears to be the only specific feature that can be linked to the loss of 5p material. The remaining dysmorphic features of this infant appear to be due specifically to the duplication of the 5q sequences. The combination of FISH, CGH, and cytogenetics has confirmed that the characteristic cry of the cri du chat syndrome is due to the deletion of the most distal part of the classic del 5p region. More importantly, our investigation has defined the duplication of 5q34 --> qter as a distinct clinical phenotype.

  1. Estudio de los Efectos Gravitomagnéticos en Cuerpos Masivos Rotantes

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  2. [Molecular response with triple therapy in patients with chronic myeloid leukemia].

    PubMed

    López-Arroyo, José Luis; Rico-Ramos, Héctor Joel; Portillo-García, Mireya Leticia

    2014-01-01

    INTRODUCCIÓN: la leucemia mieloide crónica es un trastorno mieloproliferativo provocado por la translocación t (9;22)(q34;q11). El mesilato de imatinib es un inhibidor de la tirosina cinasa útil en el tratamiento de la leucemia mieloide crónica. El objetivo de este estudio fue evaluar la respuesta molecular mayor a los 12 meses con esquema terapéutico triple, analizar la evolución de los pacientes, así como la toxicidad general y la hematológica. MÉTODOS: estudio observacional longitudinal en pacientes con leucemia mieloide crónica, tratados con interferón pegilado alfa 2a subcutáneo (90 μg/semana por cuatro semanas) + imatinib oral (800 mg/día por 30 días) + citarabina subcutánea (20 mg/m2 de superficie corporal del día 1 al 10). Se analizaron las respuestas hematológica y molecular a los 12 meses.

  3. Providing Meaningful Learning for Students of the Sixth Grade of Middle School: a Study on the Moon Phases. (Breton Title: Propiciando Aprendizagem Significativa Para Alunos do Sexto Ano do Ensino Fundamental: um Estudo sobre as Fases da Lua.) Propiciando el Aprendizaje Significativo Para Alumnos del Sexto Nivel de la Educación General Básica: un Estudio sobre Las Fases de la Luna

    NASA Astrophysics Data System (ADS)

    Darroz, Luiz Marcelo; Samudio Pérez, Carlos Ariel; da Rosa, Cleci Werner; Heineck, Renato

    2012-07-01

    We relate in this article a didactic experience studying the moon phases with a group of middle school students of a private school of the municipality of Passo Fundo, RS. Based on David Ausubel's Meaningful Learning Theory, we have sought to develop a proposal following a didactic model which simulates the phases of the Moon, as based on the previous conceptions of the students. The signs of learning were evidenced by means of memory registries of the activity. From the obtained results we believe that the proposal achieved its goals, since the students were able to identify, differentiate and transfer the phenomenon of the moon phases to new contexts. Thus, it is concluded that a methodology focused on a meaningful content for the students is fundamental to the construction and genuine grasping of what is being learned. Neste artigo, relata-se uma experiência didática de estudo das fases da Lua com uma turma do 6° ano do Ensino Fundamental, de uma escola privada do município de Passo Fundo, RS. Tendo como fundamentação teórica a Teoria da Aprendizagem Significativa de David Ausubel, buscou-se desenvolver a proposta a partir de um modelo didático que simula as fases da Lua e com base nas concepções prévias dos estudantes. Os indícios da aprendizagem foram constatados através de registros de memórias da atividade. Pelos resultados apresentados, acredita-se que a proposta alcançou seus objetivos, uma vez que os estudantes conseguiram identificar, diferenciar e transferir o fenômeno das fases da Lua para novos contextos. Assim, conclui-se que uma metodologia com enfoque em um conteúdo significativo ao estudante é fundamental para a construção e compreensão genuína do que está sendo aprendido. En este artículo se relata una experiencia didáctica de estudio de las fases de la Luna con una clase de 6º año de la educación general básica de una escuela privada del municipio de Passo Fundo, RS. Teniendo como fundamentación teórica la Teor

  4. Molecular analysis of the Smith-Magenis syndrome: a possible contiguous-gene syndrome associated with del(17)(p11.2).

    PubMed Central

    Greenberg, F; Guzzetta, V; Montes de Oca-Luna, R; Magenis, R E; Smith, A C; Richter, S F; Kondo, I; Dobyns, W B; Patel, P I; Lupski, J R

    1991-01-01

    We undertook clinical evaluation (32 cases) and molecular evaluation (31 cases) of unrelated patients affected with Smith-Magenis syndrome (SMS) associated with an interstitial deletion of band p11.2 of chromosome 17. Patients were evaluated both clinically and electrophysiologically for peripheral neuropathy, since markers showing close linkage to one form of Charcot-Marie-Tooth disease (CMT1A) map to this chromosomal region. The common clinical findings were broad flat midface with brachycephaly, broad nasal bridge, brachydactyly, speech delay, and hoarse, deep voice. Fifty-five percent of the patients showed clinical signs (e.g., decreased or absent deep tendon reflexes, pes planus or pes cavus, decreased sensitivity to pain, and decreased leg muscle mass) suggestive of peripheral neuropathy. However, unlike patients with CMT1A, these patients demonstrated normal nerve conduction velocities. Self-destructive behaviors, primarily onychotillomania and polyembolokoilamania, were observed in 67% of the patients, and significant symptoms of sleep disturbance were observed in 62%. The absence of REM sleep was demonstrated by polysomnography in two patients. Southern analysis indicated that most patients were deleted for five 17p11.2 markers--FG1 (D17S446), 1516 (D17S258), pYNM67-R5 (D17S29), pA10-41 (D17S71), and pS6.1-HB2 (D17S445)--thus defining a region which appears to be critical to SMS. The deletion was determined to be of paternal origin in nine patients and of maternal origin in six patients. The apparent random parental origin of deletion documented in 15 patients suggests that genomic imprinting does not play a role in the expression of the SMS clinical phenotype. Our findings suggest that SMS is likely a contiguous-gene deletion syndrome which comprises characteristic clinical features, developmental delay, clinical signs of peripheral neuropathy, abnormal sleep function, and specific behavioral anomalies. Images Figure 2 Figure 3 PMID:1746552

  5. Vigilando la Calidad del Agua de los Grandes Rios de la Nacion: El Programa NASQAN del Rio Grande (Rio Bravo del Norte)

    USGS Publications Warehouse

    Lurry, Dee L.; Reutter, David C.; Wells, Frank C.; Rivera, M.C.; Munoz, A.

    1998-01-01

    La Oficina del Estudio Geologico de los Estados Unidos (U.S. Geological Survey, 0 USGS) ha monitoreado la calidad del agua de la cuenca del Rio Grande (Rio Bravo del Norte) desde 1995 como parte de la rediseiiada Red Nacional para Contabilizar la Calidad del Agua de los Rios (National Stream Quality Accounting Network, o NASOAN) (Hooper and others, 1997). EI programa NASOAN fue diseiiado para caracterizar las concentraciones y el transporte de sedimento y constituyentes quimicos seleccionados, encontrados en los grandes rios de los Estados Unidos - incluyendo el Misisipi, el Colorado y el Columbia, ademas del Rio Grande. En estas cuatro cuencas, el USGS opera actualmente (1998) una red de 40 puntos de muestreo pertenecientes a NASOAN, con un enfasis en cuantificar el flujo en masa (la cantidad de material que pasa por la estacion, expresado en toneladas por dial para cada constituyente. Aplicacando un enfoque consistente, basado en la cuantificacion de flujos en la cuenca del Rio Grande, el programa NASOAN esta generando la informacion necesaria para identificar fuentes regionales de diversos contaminantes, incluyendo sustancias qui micas agricolas y trazas elementos en la cuenca. EI efecto de las grandes reservas en el Rio Grande se puede observar segun los flujos de constituyentes discurren a 10 largo del rio. EI analisis de los flujos de constituyentes a escala de la cuenca proveera los medios para evaluar la influencia de la actividad humana sobre las condiciones de calidad del agua del Rio Grande.

  6. Calidad de Imagen del Telescopio UNAM212

    NASA Astrophysics Data System (ADS)

    Cobos, F. J.; Teiada de Vargas, C.

    1987-05-01

    El telescopio UNAM2l2, del Observatorio Astronómico Nacional, situado en la Sierra de San Pedro Mártir (Baja California, México), cumplira en un futuro muy cercano siete años de uso para fines de investigación astronómica. Aunque en este tiempo no se ha efectuado un estudio sistemático acerca de su comportamiento óptico y de los factores que influyen en la calidad de las imágenes, se han realizado pruebas diversas, estudios parciales y reuniones especificas, cuyos resultados no siempre se han difundido ampliamente y generalmente no se han presentado por escrito. Es por ello que hemos creido necesario intentar una recopilación de la información existente para poder con ella establecer un diagnóstjco que, aunque no sea definitivo, sirva de base para futuros trabajos tendientes a optimizar el comportamiento óptico del telescopio. Es evidente que un buen número de las conclusiones que se presentan son resultado del trabajo de muchas personas ó de esfuerzos colectivos. Asimismo, hemos tratado de localizar información bibliográfica que pueda ser de utilidad. Nuestro objetivo primordial ha consistido en centrarnos en la óptica del telescopio y su calidad, pero también se han considerado otros aspectos que puedan afectar las imágenes obtenidas tales como: celda del primario, `seeing' local y externo, flexiones posibles en la estructura mecánica del telescopio, etc.

  7. Estudio Sobre Portadores Cronicos de Salmonellas en Manipuladores de Alimentos de la Ciudad de Iquitos (Study of Chronic Salmonella Carriers in Food Handlers in the City of Iquitos)

    DTIC Science & Technology

    1990-01-01

    manipuladores de alimentos en estudio. 779 (77.90%) fueron del sexo femcnino y 221 (22.10%) del sexo masculino. siendo el mayor porcentaje mujeres (234 - 30.04...papel de ios portadlores cr6- Woos en 460 mujeres dadas de alt. del hospital de Chile, encontrandose 34 porta- dores o sea 7.4 % excediindose las...4 sujetos 3.6 % portadores cr6nicos de Salmoncilas. 1S0 En Argentina 1974, se inves:,16 la frecuencia de Saiimoncilas en 146 manipulado- res de

  8. Clinical and molecular evidence of the consumption of broccoli, glucoraphanin and sulforaphane in humans.

    PubMed

    Conzatti, Adriana; Fróes, Fernanda Carolina Telles da Silva; Schweigert Perry, Ingrid Dalira; Souza, Carolina Guerini de

    2014-11-30

    Introducción: El sulforafano (SFN) es un isotiocianato derivado de la glucorafanina (GRA), encontrada en gran cantidad especialmente en el brócolis. Su consumo está asociado a un menor riesgo de infarto del miocardio y de cáncer. Además, sus efectos están siendo estudiados en enfermedades neurodegenerativas, diabetes y aterosclerosis, casi siempre utilizando modelos animales y cultivos celulares. Objetivos: Debido a los resultados prometedores del compuesto SFN, esta revisión buscó investigar evidencias ya documentadas en intervenciones con brócoli, GRA y SFN en humanos. Métodos: Se realizó una búsqueda en las bases de datos PubMed y Biblioteca Virtual en Salud, por dos investigadores independientes, utilizando los descriptores “broccoli” o “glucoraphanin” o “sulforaphane”, que debían constar en el título o resumen del trabajo. Se incluyeron ensayos clínicos randomizados realizados en humanos, publicados en inglés y portugués entre 2003 y 2013, y que consideraron como desenlaces de interés parámetros clínicos y moleculares de daño celular. Resultados: Se seleccionaron 17 estudios y el tipo de intervención predominante fueron brotes de brócoli. Los resultados más consistentes fueron obtenidos con los parámetros clínicos glicemia y perfil lipídico y los parámetros moleculares de estrés oxidativo, que presentaron mejora después de la intervención. Se encontraron evidencias menos sólidas respeto a la disminución de la inflamación, de la colonización por Helicobacter pylori y protección contra cáncer. Conclusión: Aunque relevantes, las evidencias del uso de brócoli, GRA y SFN en humanos son limitadas, siendo necesarios más estudios de intervención para avaluar los desenlaces de forma más consistente y producir conclusiones mejor fundamentadas.

  9. Poblacion estelar joven embebida en la nube molecular galactica asociada a la fuente IRAS 18236-1205

    NASA Astrophysics Data System (ADS)

    Romero, Ricardo Retes

    2008-06-01

    En esta tesis presento una metodología de seleccion y estudio de la población estelar embebida en la nube molecular galactica asociada a la fuente IRAS 18236-1205. La fuente IRAS posee colores de region Ultra Compacta HII (UCHII) y tiene deteccióon en monosulfuro de carbono (CS), trazador molecular de alta densidad, lo cual da la posibilidad de definir la nube molecular asociada hacia esta region. Lo anterior muestra que esta es buena candidata a región de formación estelar masiva. La metodología de seleccion de la población embebida, est à basada por una parte, en la distribución del gas molecular monoxido de carbono (13CO) asociado a la fuente IRAS, nube molecular seleccionada del mapeo Galactic Ring Survey (GRS) realizado en 13CO. Otros pasos de la seleccion, se basan en los diagramas color-color y color-magnitud con datos del cercano infrarrrojo de 2MASS. Para el estudio de la componente estelar se usaron los catalogos de fuentes puntuales en el cercano, medio y lejano infrarrojo de 2MASS, SPITZER e IRAS, respectivamente. De los diagramas color-color y color-magnitud, usando datos de 2MASS, se construyo un criterio fotométrico para identificar los objetos estelares j ovenes embebidos en la region molecular. Aplicando modelos a la distribución espectral de energía (SED) de algunos ellos, se encontraron parametros estelares de objetos estelares j ovenes embebidos de masa intermedia y alta. Adicionalmente, se encontro un objeto de masa ´ intermedia no identifiado por el catalogo de 2MASS y su efecto sobre el medio interestelar, emision en la banda de [4.5] μm de IRAC-Spitzer asociado a un outflow. Dos de los objetos seleccionados por el criterio fotometrico resultaron ser objetos estelares jovenes de alta e intermedia masa (B1V/B2V y B8V/A0V respectivamente), los cuales deben estar asociados a la emision radiativa responsable de los colores de región UC HII. Otro objeto estelar joven de baja masa (F0V/F5V) fue encontrado en la region de estudio

  10. Estudio comparativo de las moléculas isovalentes de interés atmosférico CF3Cl y CF3Br y sus correspondientes halógenos aislados Cl y Br.

    NASA Astrophysics Data System (ADS)

    Mayor, E.; Velasco, A. M.; Martín, I.; Lavín, C.

    Los estados Rydberg moleculares han suscitado en los últimos años un creciente interés entre los espectroscopistas experimentales, motivado en parte por el desarrollo de nuevas técnicas espectroscópicas capaces de investigar estos estados altamente excitados electrónicamente. Los procesos de fotoabsorción que implican estados Rydberg en los derivados halogenados del metano son de gran importancia, debido a su abundancia en la atmósfera y a sus implicaciones medioambientales. Por ello, la obtención de datos relativos a sus fuerzas de oscilador es de gran interés. En este trabajo se aborda el estudio de dichas propiedades para las moléculas isovalentes CF3Cl y CF3Br. Ambas moléculas presentan idéntica estructura electrónica para el estado fundamental por lo que se espera que sus espectros Rydberg presenten grandes similitudes, en ausencia de perturbaciones. Por ello y dada la escasez de datos relativos a fuerzas de oscilador, hemos establecido la corrección de nuestros resultados en base a las analogías esperadas en las intensidades espectrales correspondientes a transiciones análogas. Por otro lado, Novak y col. [1] han encontrado experimentalmente un marcado carácter atómico en el espectro correspondiente a estas moléculas, siendo muy similar a los de los átomos de Cl y Br. Por ello en el presente trabajo, además de establecer la comparación entre ambas moléculas hemos buscado las similitudes con sus respectivos halógenos. Los cálculos relativos a las especies moleculares se han realizado utilizando la Metodología Molécular de Orbítales de Defecto Cuántico (MQDO) [2], mientras que para el estudio de los átomos de Cl y Br se empleó la versión relativista del método (RQDO) [3].

  11. Magnetismo Molecular (Molecular Magentism)

    SciTech Connect

    Reis, Mario S; Moreira Dos Santos, Antonio F

    2010-07-01

    The new synthesis processes in chemistry open a new world of research, new and surprising materials never before found in nature can now be synthesized and, as a wonderful result, observed a series of physical phenomena never before imagined. Among these are many new materials the molecular magnets, the subject of this book and magnetic properties that are often reflections of the quantum behavior of these materials. Aside from the wonderful experience of exploring something new, the theoretical models that describe the behavior these magnetic materials are, in most cases, soluble analytically, which allows us to know in detail the physical mechanisms governing these materials. Still, the academic interest in parallel this subject, these materials have a number of properties that are promising to be used in technological devices, such as in computers quantum magnetic recording, magnetocaloric effect, spintronics and many other devices. This volume will journey through the world of molecular magnets, from the structural description of these materials to state of the art research.

  12. Estudio de distintos modelos de protuberancias solares

    NASA Astrophysics Data System (ADS)

    Cirigliano, D.; Rovira, M.; Mauas, P.

    En este trabajo presentamos perfiles de líneas del CaII, MgII y HeI calculados para distintos modelos de protuberancias, y los comparamos con observaciones obtenidas por los satélites OSO 8 y SOHO. Para obtener las poblaciones de los distintos niveles de los átomos, utilizamos un código numérico que combina las ecuaciones de transporte de radiación y equilibrio estadístico en un único sistema de ecuaciones no lineal. Los modelos básicos que consideramos para las protuberancias consisten en placas homogéneas y unidimensionales apoyadas sobre la superficie del Sol. Dichas placas se hallan estratificadas en hebras y los modelos difieren entre sí en la temperatura y ancho de la placa, en la presión a la cual se halla el plasma y en el número de hebras. A partir de estos modelos se investiga cada uno de estos parámetros libres y como influyen en la atmósfera de las protuberancias solares y en el perfil de línea de cada especie estudiada, con el objetivo de determinar las condiciones en las que se halla el material atmosférico de estas protuberancias.

  13. [Dynamic study of small metallic clusters]; Estudio Dinamico de Pequenos Agregados Metalicos

    SciTech Connect

    Lopez, M.J.; Jellinek, J.

    1995-12-31

    We present a brief introduction to computer simulation techniques (particularly to classical molecular dynamics) and their application to the study of the thermodynamic properties of a material system. The basic concepts are illustrated in the study of structural and energetic properties such as the liquid-solid transition and the fragmentation of small clusters of nickel. [Espanol] Presentamos una breve introducci{acute o}n de las t{acute e}cnicas de simulaci{acute o}n por ordenador (en particular de la Din{acute a}mica Molecular cl{acute a}sica) y de su aplicaci{acute o}n al estudio de las propiedades termodin{acute a}micas de un sistema material. Los conceptos b{acute a}sicos se ilustran en el estudio de las propieades estructurales y energ{acute e}ticas, as{acute i} como de la transici{acute o}n de fase s{acute o}lido-l{acute i}quido y de las fragmentaciones de peque{tilde n}os agregados de n{acute i}quel.

  14. Estudio de un microcable de par trenzado para la comunicacion y lectura del modulo de pixeles del experimento CMS

    NASA Astrophysics Data System (ADS)

    Oliveros Tautiva, Sandra Jimena

    The Compact Muon Solenoid (CMS) is one of the two most important experiments at the Large Hadron Collider (LHC). The pixel detector is the component closest to the collision in CMS and it receives large doses of radiation which will affect its performance. The pixel detector will be replaced by a new one after four years. The aim is to reduce material in the sensitive zone of the new pixel detector, which leads to the implementation of a type of micro twisted pair cable that will replace the existing kapton cables and some connections will be eliminated. The purpose of this work was to study the viability of using these micro twisted pair cables in the existing 40 MHz analog readout. The electrical parameters of micro cables were determined, and operational tests were performed in a module using these cables for communicating and reading. Three different lengths of micro cables were used, 1.0, 1.5 and 2.0 m, in order to compare test results with those obtained using the kapton cable. It was found that the use of these cables does not affect the programming and reading of the pixels in one module, so the micro cables are viable to be used in place of the kapton cables.

  15. Estudio del campo ocupacional del traductor en Santiago de Chile (A Study of Opportunities for Professional Translators in Santiago, Chile).

    ERIC Educational Resources Information Center

    Cabrera, Ileana; And Others

    A study of translation as a profession in Chile covered two areas: a diagnostic study of the real need for literary, scientific, and technical translations, and a followup study of graduates of the translation degree program at the Catholic Pontifical University of Chile (Santiago). The analysis considered the relationship between the need for…

  16. Estudio comparativo de cúmulos abiertos ricos en estrellas masivas

    NASA Astrophysics Data System (ADS)

    Baume, G.; Feinstein, A.; Vázquez, R. A.

    Los cúmulos abiertos muy jóvenes proveen valiosa información sobre las teorías de evolución estelar. No obstante, no se conoce mucho sobre los miembros mas débiles de estos objetos. Se llevaron a cabo entonces, estudios detallados (fotometría CCD-UBVI y polarimetría) en los cúmulos abiertos: Tr 14, Cr 272, Stok 16, NGC 6231, NGC 3293 y HM 1. Se realizó entonces un análisis comparativo entre ellos y con los objetos Pismis 20 (Vázquez et al. 1995) y NGC 5606 (Vázquez et al. 1994). En particular, se analizó la secuencia principal inferior de los distintos cúmulos, se estudió la extinción interestelar y las propiedades del polvo, se determinaron las correspondientes IMF, y se estudió la forma en que se distribuyen las estrellas menos masivas en relación con las más masivas. Como conclusiones del trabajo se puede decir que se han redeterminado con mayor precisión las distancias y las edades de los objetos bajo estudio, se han hallado varias estrellas con alta probabilidad de estar en fase de contracción y se ha notado una dispersión de edad entre las estrellas más brillantes y las menos brillantes (confirmando la idea de que la formación estelar no es simultánea ni independiente de la masa). Además, se han encontrado que las pendientes de las IMFs de estos objetos son más planas que la de las estrellas de campo y las de cúmulos más evolucionados, siendo comparable con las halladas en objetos jóvenes de la Nube Mayor de Magallanes (Will et al. 1996).

  17. Molecular breeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of molecular and genomic tools to assist selection of parents or progeny has become an integral part of modern cotton breeding. In this chapter, the basic components of molecular cotton breeding are described. These components include: molecular marker development, genetic and physical map const...

  18. Molecular Plasmonics.

    PubMed

    Wilson, Andrew J; Willets, Katherine A

    2016-06-12

    In this review, we survey recent advances in the field of molecular plasmonics beyond the traditional sensing modality. Molecular plasmonics is explored in the context of the complex interaction between plasmon resonances and molecules and the ability of molecules to support plasmons self-consistently. First, spectroscopic changes induced by the interaction between molecular and plasmonic resonances are discussed, followed by examples of how tuning molecular properties leads to active molecular plasmonic systems. Next, the role of the position and polarizability of a molecular adsorbate on surface-enhanced Raman scattering signals is examined experimentally and theoretically. Finally, we introduce recent research focused on using molecules as plasmonic materials. Each of these examples is intended to highlight the role of molecules as integral components in coupled molecule-plasmon systems, as well as to show the diversity of applications in molecular plasmonics.

  19. Primer estudio completo en rayos X del resto de supernova Puppis A.

    NASA Astrophysics Data System (ADS)

    Luna, G. J. M.; Dubner, G.; Loiseau, N.; Rodriguez-Pascual, P.; Smith, M. J. S.; Giacani, E.; Castelletti, G.

    Using new data obtained with XMM-Newton and archive data obtained with Chandra; we created the deepest and most complete image ever produced of the supernova renmant Puppis A in soft; medium and hard X-rays. Here we present the image and a precisse determation of basic parameters as well as a spectral study of the complete remmant using data of the intervening absorbing column. FULL TEXT IN SPANISH

  20. Estudio de eventos dinámicos en ondas milimétricas

    NASA Astrophysics Data System (ADS)

    Cristiani, G.; Martínez, G.; Raulin, J. P.; Giménez de Castro, G.; Rovira, M.

    El estudio de la actividad solar con el telescopio para ondas submilimétricas (SST), nos permite, por vez primera, trabajar con una resolución temporal de milisegundos. Este hecho ha permitido observar emisión nunca antes comprobada, pulsos o flashes extremadamente rápidos provenientes de las regiones activas, los cuales parecen preanunciar fulguraciones en dichas regiones. Se muestra, como ejemplo, una fulguración observada con el telescopio HASTA en Hα, y los pulsos rápidos que la preceden observados con el SST. Para cuantificar la influencia de la atmósfera terrestre en los datos registrados, se está estudiando la variabilidad temporal de las opacidades a las frecuecias de trabajo (212 y 405 Ghz), es decir los rangos de tiempo para los cuales la opacidad puede variar apreciablemente. Con este fin se calcula la eficiencia de cada canal multiplicada por la temperatura del Sol a estas frecuencias (estas son conocidas con una incerteza del 20 %). Se muestran los resultados obtenidos para cada canal, en donde se grafica este producto como función de la opacidad.

  1. Molecular pharmacognosy.

    PubMed

    Huang, LuQi; Xiao, PeiGen; Guo, LanPing; Gao, WenYuan

    2010-06-01

    This article analyzes the background and significance of molecular pharmacognosy, including the molecular identification of medicinal raw materials, phylogenetic evolution of medicinal plants and animals, evaluation and preservation of germplasm resources for medicinal plants and animals, etiology of endangerment and protection of endangered medicinal plants and animals, biosynthesis and bioregulation of active components in medicinal plants, and characteristics and the molecular bases of top-geoherbs.

  2. Acerca del moho

    EPA Pesticide Factsheets

    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

  3. Molecular motors

    NASA Astrophysics Data System (ADS)

    Allemand, Jean François Desbiolles, Pierre

    2015-10-01

    How do we move? More precisely, what are the molecular mechanisms that can explain that our muscles, made of very small components can move at a osopic scale? To answer these questions we must introduce molecular motors. Those motors are proteins, or small protein assemblies that, in our cells, transform chemical energy into mechanical work. Then, like we could do for a oscopic motor, used in a car or in a fan, we are going to study the basic behavior of these molecular machines, present what are their energy sources, calculate their power, their yield. If molecular motors are crucial for our oscopic movements, we are going to see that they are also essential to cellular transport and that considering the activity of some enzymes as molecular motors bring some interesting new insights on their activity.

  4. Molecular Descriptors

    NASA Astrophysics Data System (ADS)

    Consonni, Viviana; Todeschini, Roberto

    In the last decades, several scientific researches have been focused on studying how to encompass and convert - by a theoretical pathway - the information encoded in the molecular structure into one or more numbers used to establish quantitative relationships between structures and properties, biological activities, or other experimental properties. Molecular descriptors are formally mathematical representations of a molecule obtained by a well-specified algorithm applied to a defined molecular representation or a well-specified experimental procedure. They play a fundamental role in chemistry, pharmaceutical sciences, environmental protection policy, toxicology, ecotoxicology, health research, and quality control. Evidence of the interest of the scientific community in the molecular descriptors is provided by the huge number of descriptors proposed up today: more than 5000 descriptors derived from different theories and approaches are defined in the literature and most of them can be calculated by means of dedicated software applications. Molecular descriptors are of outstanding importance in the research fields of quantitative structure-activity relationships (QSARs) and quantitative structure-property relationships (QSPRs), where they are the independent chemical information used to predict the properties of interest. Along with the definition of appropriate molecular descriptors, the molecular structure representation and the mathematical tools for deriving and assessing models are other fundamental components of the QSAR/QSPR approach. The remarkable progress during the last few years in chemometrics and chemoinformatics has led to new strategies for finding mathematical meaningful relationships between the molecular structure and biological activities, physico-chemical, toxicological, and environmental properties of chemicals. Different approaches for deriving molecular descriptors here reviewed and some of the most relevant descriptors are presented in

  5. Molecular Astrophysics

    NASA Astrophysics Data System (ADS)

    Hartquist, T. W.

    2005-07-01

    Part I. Molecular Clouds and the Distribution of Molecules in the Milky Way and Other Galaxies: 1. Molecular clouds in the Milky Way P. Friberg and A. Hjalmarson; 2. Molecules in galaxies L. Blitz; Part II. Diffuse Molecular Clouds: 3. Diffuse cloud chemistry E. F. Van Dishoeck; 4. Observations of velocity and density structure in diffuse clouds W. D. Langer; 5. Shock chemistry in diffuse clouds T. W. Hartquist, D. R. Flower and G. Pineau des Forets; Part III. Quiescent Dense Clouds: 6. Chemical modelling of quiescent dense interstellar clouds T. J. Millar; 7. Interstellar grain chemistry V. Buch; 8. Large molecules and small grains in astrophysics S. H. Lepp; Part IV. Studies of Molecular Processes: 9. Molecular photoabsorption processes K. P. Kirby; 10. Interstellar ion chemistry: laboratory studies D. Smith, N. G. Adams and E. E. Ferguson; 11. Theoretical considerations on some collisional processes D. R. Bates; 12. Collisional excitation processes E. Roueff; 13. Neutral reactions at Low and High Temperatures M. M. Graff; Part V. Atomic Species in Dense Clouds: 14. Observations of atomic species in dense clouds G. J. Melnick; 15. Ultraviolet radiation in molecular clouds W. G. Roberge; 16. Cosmic ray induced photodissociation and photoionization of interstellar molecules R. Gredel; 17. Chemistry in the molecular cloud Barnard 5 S. B. Charnley and D. A. Williams; 18. Molecular cloud structure, motions, and evolution P. C. Myers; Part VI. H in Regions of Massive Star Formation: 19. Infrared observations of line emission from molecular hydrogen T. R. Geballe; 20. Shocks in dense molecular clouds D. F. Chernoff and C. F. McKee; 21. Dissociative shocks D. A. Neufeld; 22. Infrared molecular hydrogen emission from interstellar photodissociation regions A. Sternberg; Part VII. Molecules Near Stars and in Stellar Ejecta: 23. Masers J. M. Moran; 24. Chemistry in the circumstellar envelopes around mass-losing red giants M. Jura; 25. Atoms and molecules in supernova 1987a R

  6. [Active interventions in hypercholesteroloemia patients with high cardiovascular risk in primary care; estudio ESPROCOL].

    PubMed

    Tárraga López, Pedro J; García-Norro Herreros, F J; Tárraga Marcos, Loreto; Solera Albero, Juan; González López, Esteban; Ruiz García, Antonio; Pallarés Carratalá, Vicente; Castro Navarro, José Luis; Alins Presas, Josep; Panisello Royo, Josefa María

    2015-06-01

    Introducción: la hipercolesterolemia es uno de los principales factores de riesgo modificables de la enfermedad cardiovascular (ECV). Su reducción disminuye la morbimortalidad por cardiopatía isquémica y ECV en general, en prevención primaria y, especialmente, en prevención secundaria. Objetivo: comprobar si una práctica clínica protocolizada e intensiva permite vencer la inercia y alcanzar el objetivo terapéutico (OT) de c-LDL < 100 mg/dL en pacientes de alto riesgo asistidos en Atención Primaria (AP) de nuestro país. Metodología: estudio epidemiológico, prospectivo, multicentrico, realizado en centros de AP de diferentes CC. AA. Mediante muestreo consecutivo se incluyeron 310 pacientes de alto riesgo cardiovascular (diabéticos o con ECV establecida), tratados previamente con estatinas, que no alcanzaban el OT de c-LDL. Resultados: los sujetos del estudio tenían una edad media de 65,2 años, de los que el 60,32 % eran varones. El 41,64 % presentaban un EVC previo, infarto agudo de miocardio (20,33 %), angina (16,07 %), ictus/AIT (9,19 %), artropatía (5,25 %), diabetes (70,87 %), hipertensión (71,01 %) y obesidad abdominal (69,62 %). El 43,57 % (IC95 %: 37,21; 50,08) de los pacientes que realizaron la segunda visita (241) consiguieron el OT. El 62,50 % (IC95 %: 55,68; 68,98) de los que realizaron la tercera (216) consiguieron el OT. Finalmente, el 77,56 % (IC95 %: 72,13; 83,08) de los pacientes que realizaron la última visita (205) consiguieron el OT. A lo largo del estudio hubo una reducción de los niveles de c-LDL desde los 135,6 mg/dL en la visita basal, 107,4 mg/dL en la segunda visita, 97,3 mg/dL en la tercera visita, hasta los 90,7 mg/dL en la visita final (p < 0,0001). El incremento de c-HDL entre la visita basal (50,9 mg/dL) y la final (53,6 mg/dL) también fue significativo (p = 0,013). Conclusiones: la reevaluación e intensificación del tratamiento en pacientes de alto riesgo cardiovascular atendidos en Atención Primaria, aplicando

  7. Estudios sobre Educacion, 2002 (Studies on Education, 2002).

    ERIC Educational Resources Information Center

    Estudios sobre Educacion, 2002

    2002-01-01

    This journal, which provides abstracts of its articles mostly in Spanish and a few in English, contains studies (estudios) and notes (notas) about educational issues, as well as relevant book reviews (recensiones). Studies in this issue (No. 3, 2002) are: "Unprotected Time of Early Adolescence and Intergenerational Relations: A New…

  8. Percepcion de los profesores universitarios acerca del concepto cultura cientifica y de sus implicaciones en el nuevo bachillerato del Recinto de Rio Piedras de la Universidad de Puerto Rico

    NASA Astrophysics Data System (ADS)

    Ramos Pastrana, Nilsa

    El Senado Academico del Recinto de Rio Piedras de la Universidad de Puerto Rico aprobo en el ano academico 2005-2006 la Certificacion 46, que contiene los lineamientos de un nuevo bachillerato. Este nuevo bachillerato introdujo cambios significativos en el curriculo tradicional. Entre ellos se encuentra la reduccion del componente de educacion general y el de Ciencias Biologicas en particular. La reduccion de creditos en el componente de Ciencias Biologicas ha obligado a reevaluar el concepto de cultura cientifica que desarrollan esos cursos. El proposito del estudio consistio en auscultar las percepciones de los profesores de las Facultades de Administracion de Empresas, Humanidades, Ciencias Sociales, Ciencias Naturales, Educacion y Estudios Generales del Recinto de Rio Piedras de la Universidad de Puerto Rico en torno al concepto de cultura cientifica, los contenidos disciplinares del curso de Ciencias Biologicas y la reduccion de creditos en el nuevo bachillerato. Las preguntas que guiaron la investigacion fueron: ¿cuales son las percepciones que tienen los profesores de las Facultades de Administracion de Empresas, Ciencias Sociales, Estudios Generales, Ciencias Naturales, Humanidades y Educacion, en torno al concepto de cultura cientifica y los contenidos disciplinares del curso de Ciencias Biologicas? ¿cuales son las percepciones que tienen los profesores de Ciencias Biologicas en torno al concepto cultura cientifica y los contenidos disciplinares del curso de Ciencias Biologicas? ¿existen diferencias significativas por facultad, genero, experiencia, rango y nombramiento en las percepciones que tienen los profesores del Recinto de Rio Piedras de la Universidad de Puerto Rico sobre los elementos que caracterizan la cultura cientifica y los contenidos biologicos que deben tener los egresados del Recinto? ¿que implicaciones curriculares tienen estos testimonios en el desarrollo del concepto de cultura cientifica en el nuevo bachillerato? Para realizar la

  9. Molecular fountain.

    SciTech Connect

    Strecker, Kevin E.; Chandler, David W.

    2009-09-01

    A molecular fountain directs slowly moving molecules against gravity to further slow them to translational energies that they can be trapped and studied. If the molecules are initially slow enough they will return some time later to the position from which they were launched. Because this round trip time can be on the order of a second a single molecule can be observed for times sufficient to perform Hz level spectroscopy. The goal of this LDRD proposal was to construct a novel Molecular Fountain apparatus capable of producing dilute samples of molecules at near zero temperatures in well-defined user-selectable, quantum states. The slowly moving molecules used in this research are produced by the previously developed Kinematic Cooling technique, which uses a crossed atomic and molecular beam apparatus to generate single rotational level molecular samples moving slowly in the laboratory reference frame. The Kinematic Cooling technique produces cold molecules from a supersonic molecular beam via single collisions with a supersonic atomic beam. A single collision of an atom with a molecule occurring at the correct energy and relative velocity can cause a small fraction of the molecules to move very slowly vertically against gravity in the laboratory. These slowly moving molecules are captured by an electrostatic hexapole guiding field that both orients and focuses the molecules. The molecules are focused into the ionization region of a time-of-flight mass spectrometer and are ionized by laser radiation. The new molecular fountain apparatus was built utilizing a new design for molecular beam apparatus that has allowed us to miniaturize the apparatus. This new design minimizes the volumes and surface area of the machine allowing smaller pumps to maintain the necessary background pressures needed for these experiments.

  10. Agregación de para-H2 en chorros supersónicos: del dímero al sólido

    NASA Astrophysics Data System (ADS)

    María Fernández, José

    En este trabajo se mostrarán los estudios de expansiones supersónicas de para-H2 desde toberas criogénicas, realizados en el laboratorio de Fluidodinámica Molecular del IEM. Hemos registrado los espectros Raman de dichas expansiones en el intervalo de frecuencias de 4145 a 4162 cm-1, próximo a la línea Q(0) del monómero no rotante H2, a 4161.18 cm-1. En el espectro Raman, además de la línea Q(0) del monómero, se observan unos picos débiles, que, por su comportamiento con la temperatura de la tobera y la distancia a la misma, asignamos a la transición homóloga en agregados de p-H2. Dependiendo de las condiciones, se observan agregados pequeños (de 2 a 13 moléculas de p-H2), agregados medios y masivos, y se llega incluso al líquido y al sólido. Las asignaciones se apoyan en un modelo sencillo, basado en la perturbación, debida al potencial intermolecular, de los estados vibracionales v=0 y v=1 en los agregados de p-H2. Se mostrarán detalles de la instalación experimental, ejemplos de los espectros obtenidos en diversas condiciones, y detalles de la interpretación cuantitativa.

  11. "Estudio tribologico de aceros para moldes. Aplicacion al moldeo por inyeccion de polibutilentereftalato reforzado con fibra de vidrio"

    NASA Astrophysics Data System (ADS)

    Martinez Mateo, Isidoro Jose

    fabricacion del molde, tienen una gran influencia sobre su comportamiento en servicio a lo largo de la vida util del molde. En la primera parte del presente estudio, a partir de ensayos punzon sobre disco, se ha determinado la relacion entre la resistencia al desgaste y la dureza de aceros para moldes obtenidos a partir de bloques de gran espesor, estudiando los principales mecanismos de desgaste que tienen lugar. A continuacion, con el fin de determinar el dano superficial que sufren los aceros para moldes en condiciones reales de inyeccion, se han estudiado distintos tipos de aceros utilizados comercialmente en moldes de inyeccion de polimeros y materiales compuestos, seleccionando las condiciones de operacion para determinar la variacion de la rugosidad superficial del acero en funcion del material inyectado, del numero de operaciones sucesivas de inyeccion y de la orientacion del flujo de inyeccion, mediante tecnicas de perfilometria optica y microscopia electronica de barrido. Ademas del dano superficial sufrido por el acero con el numero de piezas inyectadas, tambien se ha determinado la evolucion de la rugosidad superficial de los materiales inyectados, polibutilentereftalato (PBT) puro y materiales compuestos derivados de PBT por adicion de un 20 o un 50% en peso de fibra de vidrio. En el caso de las piezas inyectadas, se ha caracterizado su microestructura en funcion del flujo de inyeccion y de la densidad de fibra, se han determinado sus propiedades termicas y dinamico-mecanicas, asi como la variacion de la rugosidad superficial de las piezas inyectadas con el numero de operaciones de inyeccion y con la geometria de las distintas secciones de las piezas. Finalmente, se ha evaluado la resistencia a la abrasion de PBT reforzado con un 50% de fibra, en funcion del numero de piezas inyectadas y de la direccion de rayado con respecto a la orientacion del flujo de inyeccion.

  12. Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: High-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bed

    NASA Technical Reports Server (NTRS)

    Kenig, F.; Damste, J. S.; Frewin, N. L.; Hayes, J. M.; De Leeuw, J. W.

    1995-01-01

    The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to recover sulphur-bound lipids from the polar and asphaltene fractions. Carbon isotopic compositions (delta vs PDB) of free hydrocarbons and of S-bound hydrocarbons were also measured. Relationships between these carbon skeletons, precursor biolipids, and the organisms producing them could then be examined. Concentrations of S-bound lipids and free hydrocarbons and their delta values were plotted vs depth in the marl bed and the profiles were interpreted in terms of variations in source organisms, 13 C contents of the carbon source, and environmentally induced changes in isotopic fractionation. The overall range of delta values measured was 24.7%, from -11.6% for a component derived from green sulphur bacteria (Chlorobiaceae) to -36.3% for a lipid derived from purple sulphur bacteria (Chromatiaceae). Deconvolution of mixtures of components deriving from multiple sources (green and purple sulphur bacteria, coccolithophorids, microalgae and higher plants) was sometimes possible because both quantitative and isotopic data were available and because either the free or S-bound pool sometimes appeared to contain material from a single source. Several free n-alkanes and S-bound lipids appeared to be specific products of upper-water-column primary producers (i.e. algae and cyanobacteria). Others derived from anaerobic photoautotrophs and from heterotrophic protozoa (ciliates), which apparently fed partly on Chlorobiaceae. Four groups of n-alkanes produced by algae or cyanobacteria were also recognized based on systematic variations of abundance and isotopic composition with depth. For hydrocarbons probably derived from microalgae, isotopic variations are well correlated with

  13. Molecular gastronomy

    NASA Astrophysics Data System (ADS)

    This, Hervé

    2005-01-01

    For centuries, cooks have been applying recipes without looking for the mechanisms of the culinary transformations. A scientific discipline that explores these changes from raw ingredients to eating the final dish, is developing into its own field, termed molecular gastronomy. Here, one of the founders of the discipline discusses its aims and importance.

  14. Extensión del Formalismo de Orbitales de Defecto Cuántico al tratamiento del efecto Stark (SQDO).

    NASA Astrophysics Data System (ADS)

    Menéndez, J. M.; Martín, I.; Velasco, A. M.

    El estudio experimental de las interacciones de átomos Rydberg altamente excitados con campos eléctricos ha experimentado un creciente interés durante las dos últimas décadas debido, en gran medida, al desarrollo de nuevas técnicas para crear y estudiar átomos Rydberg en el laboratorio. Acompañando a estas nuevas técnicas experimentales, es necesario el desarrollo de modelos teóricos que nos permitan contrastar sus medidas y conocer mejor los fundamentos de los mismos. Desde el punto de vista teórico el conocimiento del desdoblamiento de los niveles energéticos de un átomo en función de la magnitud del campo eléctrico aplicado (lo que se conoce como mapa Stark) es el mejor punto de partida para la descripción del sistema y un prerrequisito fundamental para el cálculo de distintas propiedades atómicas en presencia del campo eléctrico tales como intensidades de transición, umbrales de ionización de campo eléctrico, tiempos de vida, posición y anchura de cruces evitados, etc. En este trabajo presentamos la adaptación del método de orbitales de defecto cuántico [1,2,3] al tratamiento del efecto Stark (SQDO) [4] y su aplicación al cálculo de los desdoblamientos energéticos y fuerzas de oscilador de estados Rydberg en los átomos de Li, Na y K. El propósito de este estudio es, por un lado, desarrollar métodos fiables para la determinación de propiedades atómicas en presencia de campos eléctricos y, por otro, mostrar la fiabilidad de las funciones de onda QDO en la descripción del efecto Stark en sistemas atómicos.

  15. Molecular Thermometry

    PubMed Central

    McCabe, Kevin M.; Hernandez, Mark

    2010-01-01

    Conventional temperature measurements rely on material responses to heat, which can be detected visually. When Galileo developed an air expansion based device to detect temperature changes, Santorio, a contemporary physician, added a scale to create the first thermometer. With this instrument, patients’ temperatures could be measured, recorded and related to changing health conditions. Today, advances in materials science and bioengineering provide new ways to report temperature at the molecular level in real time. In this review the scientific foundations and history of thermometry underpin a discussion of the discoveries emerging from the field of molecular thermometry. Intracellular nanogels and heat sensing biomolecules have been shown to accurately report temperature changes at the nano-scale. Various systems will soon provide the ability to accurately measure temperature changes at the tissue, cellular, and even sub-cellular level, allowing for detection and monitoring of very small changes in local temperature. In the clinic this will lead to enhanced detection of tumors and localized infection, and accurate and precise monitoring of hyperthermia based therapies. Some nanomaterial systems have even demonstrated a theranostic capacity for heat-sensitive, local delivery of chemotherapeutics. Just as early thermometry moved into the clinic, so too will these molecular thermometers. PMID:20139796

  16. Molecular Imprinting

    NASA Astrophysics Data System (ADS)

    Dufaud, V.; Bonneviot, L.

    Our senses of smell and taste are able to recognise molecules selectively, to the point where they can even discriminate between different chiral states. This property, called molecular recognition, is essential to all forms of life [1]. It is based on the principle of a specific interaction between a receptor or host and a target molecule, which will be identified among a multitude of others, then selectively adsorbed. If the host is endowed with reactive functions, the attached molecule may be transported or transformed. Enzymes are the archetypal host molecules exploiting the idea of molecular recognition. Their complexation sites comprise a hydrophobic pocket with definite shape within which amino acid residues are located in a precisely defined way. The combined effect of these different characteristics underlies not only the affinity for some specific substrate, but also the transformation of this substrate into the desired product [2]. In fact, the phenomena actually brought into play are much more involved, being made up of an ensemble of physicochemical events that act together in a cooperative way, either simultaneously or sequentially, and in which the molecular processes are difficult to follow in detail.

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

    NASA Astrophysics Data System (ADS)

    Delgado, Isabel C.

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

  18. Espectroscopia del Cometa Halley

    NASA Astrophysics Data System (ADS)

    Naranjo, O.; Fuenmayor, F.; Ferrin, L.; Bulka, P.; Mendoza, C.

    1987-05-01

    Se reportan observaciones espectroscópicas del cometa Halley. Los espectros fueron tomados usando el espectrógrafo del telescopio reflector de 1 metro del Observatorio Nacional de Venezuela. Se utilizó óptica azul, con una red de difracción de 600 lineas/min, obteniéndose una dispersión de 74.2 A/mm y una resolución de 2.5 A, en el rango espectral de 3500 a 6500 A. Seis placas fueron tomadas con emulsión IIa-O y dos con IIa-D. Los tiempos de exposición fueron entre 10 y 150 minutos. El cometa se encontraba entre 0.70 y 1.04 UA del Sol, y entre 1.28 y 0.73 UA de la Tierra. Las emisiones más prominentes en el espectro, son las del CN, C2, y C3. Otras emisiones detectadas corresponden a CH, NH2 y Na. Los espectros muestran un fuerte continuo, indicando un contenido significativo de polvo. Se detectó mayor intensidad del contínuo, en la dirección anti solar, lo cual es evidencia de la cola de polvo.

  19. Molecular Plasmonics.

    PubMed

    Lauchner, Adam; Schlather, Andrea E; Manjavacas, Alejandro; Cui, Yao; McClain, Michael J; Stec, Grant J; García de Abajo, F Javier; Nordlander, Peter; Halas, Naomi J

    2015-09-09

    Graphene supports surface plasmons that have been observed to be both electrically and geometrically tunable in the mid- to far-infrared spectral regions. In particular, it has been demonstrated that graphene plasmons can be tuned across a wide spectral range spanning from the mid-infrared to the terahertz. The identification of a general class of plasmonic excitations in systems containing only a few dozen atoms permits us to extend this versatility into the visible and ultraviolet. As appealing as this extension might be for active nanoscale manipulation of visible light, its realization constitutes a formidable technical challenge. We experimentally demonstrate the existence of molecular plasmon resonances in the visible for ionized polycyclic aromatic hydrocarbons (PAHs), which we reversibly switch by adding, then removing, a single electron from the molecule. The charged PAHs display intense absorption in the visible regime with electrical and geometrical tunability analogous to the plasmonic resonances of much larger nanographene systems. Finally, we also use the switchable molecular plasmon in anthracene to demonstrate a proof-of-concept low-voltage electrochromic device.

  20. Molecular spintronics.

    PubMed

    Sanvito, Stefano

    2011-06-01

    The electron spin made its debut in the device world only two decades ago but today our ability of detecting the spin state of a moving electron underpins the entire magnetic data storage industry. This technological revolution has been driven by a constant improvement in our understanding on how spins can be injected, manipulated and detected in the solid state, a field which is collectively named Spintronics. Recently a number of pioneering experiments and theoretical works suggest that organic materials can offer similar and perhaps superior performances in making spin-devices than the more conventional inorganic metals and semiconductors. Furthermore they can pave the way for radically new device concepts. This is Molecular Spintronics, a blossoming research area aimed at exploring how the unique properties of the organic world can marry the requirements of spin-devices. Importantly, after a first phase, where most of the research was focussed on exporting the concepts of inorganic spintronics to organic materials, the field has moved to a more mature age, where the exploitation of the unique properties of molecules has begun to emerge. Molecular spintronics now collects a diverse and interdisciplinary community ranging from device physicists to synthetic chemists to surface scientists. In this critical review, I will survey this fascinating, rapidly evolving, field with a particular eye on new directions and opportunities. The main differences and challenges with respect to standard spintronics will be discussed and so will be the potential cross-fertilization with other fields (177 references).

  1. Molecular paleontology.

    PubMed

    Marota, I; Rollo, F

    2002-01-01

    Molecular paleontology, i.e., the recovery of DNA from ancient human, animal, and plant remains is an innovative research field that has received progressively more attention from the scientific community since the 1980s. In the last decade, the field was punctuated by claims which aroused great interest but eventually turned out to be fakes--the most famous being the sequence of dinosaur DNA later shown to be of human origin. At present, the discipline is characterized by some certainties and many doubts. We know, for example, that we have reasonable chances to recover authentic DNA from a mammoth carcass, while our chances are negligible (or nonexistent) in the case of a dynastic mummy from Egypt. On the other hand, though we are developing convincing models of DNA decay in bone, we are not yet able to predict whether a certain paleontological or archeological site will yield material amenable to DNA analysis. This article reviews some of the most important and promising investigations using molecular paleontology approaches, such as studies on the conservation of DNA in human bone, the quest for ancient DNA in permafrost-frozen fauna, the Tyrolean iceman, and the Neandertals.

  2. Molecular Fountain

    NASA Astrophysics Data System (ADS)

    Cheng, Cunfeng; van der Poel, Aernout P. P.; Jansen, Paul; Quintero-Pérez, Marina; Wall, Thomas E.; Ubachs, Wim; Bethlem, Hendrick L.

    2016-12-01

    The resolution of any spectroscopic or interferometric experiment is ultimately limited by the total time a particle is interrogated. Here we demonstrate the first molecular fountain, a development which permits hitherto unattainably long interrogation times with molecules. In our experiments, ammonia molecules are decelerated and cooled using electric fields, launched upwards with a velocity between 1.4 and 1.9 m/s and observed as they fall back under gravity. A combination of quadrupole lenses and bunching elements is used to shape the beam such that it has a large position spread and a small velocity spread (corresponding to a transverse temperature of <10 μ K and a longitudinal temperature of <1 μ K ) when the molecules are in free fall, while being strongly focused at the detection region. The molecules are in free fall for up to 266 ms, making it possible, in principle, to perform sub-Hz measurements in molecular systems and paving the way for stringent tests of fundamental physics theories.

  3. The novel c.247_249delTTC (p.F83del) GJB2 mutation in a family with prelingual sensorineural deafness.

    PubMed

    Petersen, Michael B; Grigoriadou, Maria; Koutroumpe, Maria; Kokotas, Haris

    2012-07-01

    Non-syndromic hearing loss is one of the most common hereditary determined diseases in human, and the disease is a genetically heterogeneous disorder. Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of non-syndromic recessive hearing impairment in many countries and are largely dependent on ethnic groups. Due to the high frequency of the c.35delG GJB2 mutation in the Greek population, we have previously suggested that Greek patients with sensorineural, non-syndromic deafness should be tested for the c.35delG mutation and the coding region of the GJB2 gene should be sequenced in c.35delG heterozygotes. Here we present on the clinical and molecular genetic evaluation of a family suffering from prelingual, sensorineural, non-syndromic deafness. A novel c.247_249delTTC (p.F83del) GJB2 mutation was detected in compound heterozygosity with the c.35delG GJB2 mutation in the proband and was later confirmed in the father, while the mother was homozygous for the c.35delG GJB2 mutation. We conclude that compound heterozygosity of the novel c.247_249delTTC (p.F83del) and the c.35delG mutations in the GJB2 gene was the cause of deafness in the proband and his father.

  4. Molecular Modeling

    NASA Astrophysics Data System (ADS)

    Holmes, Jon L.

    1999-06-01

    Molecular modeling has trickled down from the realm of pharmaceutical and research laboratories into the realm of undergraduate chemistry instruction. It has opened avenues for the visualization of chemical concepts that previously were difficult or impossible to convey. I am sure that many of you have developed exercises using the various molecular modeling tools. It is the desire of this Journal to become an avenue for you to share these exercises among your colleagues. It is to this end that Ron Starkey has agreed to edit such a column and to publish not only the description of such exercises, but also the software documents they use. The WWW is the obvious medium to distribute this combination and so accepted submissions will appear online as a feature of JCE Internet. Typical molecular modeling exercise: finding conformation energies. Molecular Modeling Exercises and Experiments is the latest feature column of JCE Internet, joining Conceptual Questions and Challenge Problems, Hal's Picks, and Mathcad in the Chemistry Curriculum. JCE Internet continues to seek submissions in these areas of interest and submissions of general interest. If you have developed materials and would like to submit them, please see our Guide to Submissions for more information. The Chemical Education Resource Shelf, Equipment Buyers Guide, and WWW Site Review would also like to hear about chemistry textbooks and software, equipment, and WWW sites, respectively. Please consult JCE Internet Features to learn more about these resources at JCE Online. Email Announcements Would you like to be informed by email when the latest issue of the Journal is available online? when a new JCE Software title is shipping? when a new JCE Internet article has been published or is available for Open Review? when your subscription is about to expire? A new feature of JCE Online makes this possible. Visit our Guestbook to learn how. When

  5. Molecular Biosignatures

    NASA Astrophysics Data System (ADS)

    Summons, Roger E.; Albrecht, Pierre; McDonald, Gene; Moldowan, J. Michael

    2008-03-01

    Life, as we know it, is based on carbon chemistry operating in an aqueous environment. Living organisms process chemicals, make copies of themselves, are autonomous and evolve in concert with the environment. All these characteristics are driven by, and operate through, carbon chemistry. The carbon chemistry of living systems is an exact branch of science and we have detailed knowledge of the basic metabolic and reproductive machinery of living organisms. We can recognise the residual biochemicals long after life has expired and otherwise lost most life-defining features. Carbon chemistry provides a tool for identifying extant and extinct life on Earth and, potentially, throughout the Universe. In recognizing that certain distinctive compounds isolable from living systems had related fossil derivatives, organic geochemists coined the term biological marker compound or biomarker (e.g. Eglinton et al. in Science 145:263-264, 1964) to describe them. In this terminology, biomarkers are metabolites or biochemicals by which we can identify particular kinds of living organisms as well as the molecular fossil derivatives by which we identify defunct counterparts. The terms biomarker and molecular biosignature are synonymous. A defining characteristic of terrestrial life is its metabolic versatility and adaptability and it is reasonable to expect that this is universal. Different physiologies operate for carbon acquisition, the garnering of energy and the storage and processing of information. As well as having a range of metabolisms, organisms build biomass suited to specific physical environments, habitats and their ecological imperatives. This overall ‘metabolic diversity’ manifests itself in an enormous variety of accompanying product molecules (i.e. natural products). The whole field of organic chemistry grew from their study and now provides tools to link metabolism (i.e. physiology) to the occurrence of biomarkers specific to, and diagnostic for, particular kinds

  6. Estudio de la estructura logica utilizada en la ensenanza y el aprendizaje de los conceptos sobre el comportamiento de gases en el curso introductorio de quimica a nivel universitario

    NASA Astrophysics Data System (ADS)

    Costa Diaz, Agnes

    El estudio que se presenta es de caracter cualitativo, un estudio multicasos donde se estudia la estructura logica utilizada por cuatro (4) profesores universitarios que ensenan el curso introductorio de quimica, en la planificacion, presentacion y evaluacion del tema sobre el comportamiento de los gases. Se utilizaron varias fuentes de informacion como: cuestionarios de profesores y estudiantes, entrevistas, grabaciones videomagnetofonicas, materiales didacticos y una prueba conceptual, entre otros. La informacion recopilada fue analizada de acuerdo al orden logico del contenido presentado, el estilo de ensenanza del profesor, las tecnicas y estrategias utilizadas para el desarrollo de destrezas de pensamiento, el ambiente fisico en el salon de clase y los instrumentos de evaluacion y avaluo. El estudio demuestra que lo que los profesores piensan y planifican para hacer sus presentaciones no necesariamente es lo que ocurre en el salon de clases. El desarrollo de destrezas de pensamiento, que constituye una prioridad de los profesores, no se elaboran efectivamente. El uso de las estrategias de resolucion de problemas numericos predomino. La participacion del estudiante en el salon de clases fue limitada y no se logro demostrar el desarrollo de las destrezas de pensamiento deseadas. Aunque los profesores tienen su propio estilo de ensenanza, el orden logico del contenido presentado en clase fue el mismo o siguio muy de cerca el orden establecido por el libro de texto. Los profesores utilizaron preferentemente la tiza y la pizarra para sus presentaciones y la dinamica en el salon de clases fue esencialmente tradicional. Los profesores hicieron su presentacion y los estudiantes copiaron pasivamente la informacion. Las evaluaciones de los estudiantes fueron esencialmente, pruebas escritas de seleccion multiple de acuerdo con el estilo en que se les enseno. El avaluo fue casi inexistente. La prueba conceptual administrada revela un aprendizaje pobre en los conceptos mas

  7. Estudios sobre Educacion, 2002 (Studies on Education, 2002).

    ERIC Educational Resources Information Center

    Estudios sobre Educacion, 2002

    2002-01-01

    This scholarly journal deals with the study of education. Articles in this second issue are: "La Vertebracion Academica de la Formacion Inicial del Profesorado" (The Academic Backbone of the Initial Formation of Teachers) (Jose M. Esteve); "Deficiencia Visual en el Nino" (Visual Deficiency in the Young Child) (Feli Peralta;…

  8. Prevalencia y factores de riesgo para infecciones del tracto urinario de inicio en la comunidad causadas por Escherichia coli productor de betalactamasas de espectro extendido en Colombia

    PubMed Central

    Blanco, Victor M.; Maya, Juan J.; Correa, Adriana; Perenguez, Marcela; Muñoz, Juan S.; Motoa, Gabriel; Pallares, Christian J.; Rosso, Fernando; Matta, Lorena; Celis, Yamile; Garzon, Martha; Villegas, y María V.

    2016-01-01

    RESUMEN Introducción Las infecciones del tracto urinario (ITU) son frecuentes en la comunidad. Sin embargo, la información de aislamientos resistentes en este contexto es limitada en Latinoamérica. Este estudio tiene como objetivo determinar la prevalencia y los factores de riesgo asociados con ITU de inicio en la comunidad (ITU-IC) causadas por Escherichia coli productor de betalactamasas de espectro extendido (BLEE) en Colombia. Materiales y métodos Entre agosto y diciembre de 2011 se realizó un estudio de casos y controles en 3 instituciones de salud de tercer nivel en Colombia. Se invitó a participar a todos los pacientes admitidos a urgencias con diagnóstico probable de ITU-IC, y se les pidió una muestra de orina. En los aislamien-tos de E. coli se realizaron pruebas confirmatorias para BLEE, susceptibilidad antibiótica, caracterización molecular (PCR en tiempo real para genes bla, repetitive element palindromic PCR [rep-PCR], multilocus sequence typing [MLST] y factores de virulencia por PCR). Se obtuvo información clínica y epidemiológica, y posteriormente se realizó el análisis estadístico. Resultados De los 2.124 pacientes seleccionados, 629 tuvieron un urocultivo positivo, en 431 de estos se aisló E. coli, 54 fueron positivos para BLEE y 29 correspondieron a CTX-M-15. La mayoría de los aislamientos de E. coli productor de BLEE fueron sensibles a ertapenem, fosfomicina y amikacina. La ITU complicada se asoció fuertemente con infecciones por E. coli productor de BLEE (OR = 3,89; IC 95%: 1,10–13,89; p = 0,03). E. coli productor de CTX-M-15 mostró 10 electroferotipos diferentes; de estos, el 65% correspondieron al ST131. La mayoría de estos aislamientos tuvieron 8 de los 9 factores de virulencia analizados. Discusión E. coli portador del gen blaCTX-M-15 asociado al ST131 sigue siendo frecuente en Colombia. La presencia de ITU-IC complicada aumenta el riesgo de tener E. coli productor de BLEE, lo cual debe tenerse en cuenta para ofrecer

  9. Medición de densidades medias de meteoritos: test del método de inmersión

    NASA Astrophysics Data System (ADS)

    Steren, G.

    Se evaluó una técnica simple para medir las densidades medias de meteoritos, basada en el Método de Arquímedes y que utiliza cuentas de vidrio de 40μ en lugar de un fluído esto presenta la ventaja de no ser intrusivo ni químicamente reactivo (D.Britt and G.Consolmagno, 1996, B.A.A.S.28,1106). El estudio, realizado en junio de este año por participantes de la VI Escuela de Verano del Observatorio del Vaticano, empleó 37 muestras de la colección del Observatorio del Vaticano, de las cuales 26 eran Condritas, 1 Pallasita y 1 Howardita; algunas de ellas ya habian sido estudiadas por otras técnicas aunque también se incluyeron muestras no estudiadas anteriormente.

  10. Nanoparticulas basadas en complejos de Fe(II) con transicion de espin: sintesis, caracterizacion y aplicaciones en electronica molecular

    NASA Astrophysics Data System (ADS)

    Monrabal Capilla, Maria

    Esta tesis doctoral esta organizada en 5 capitulos y esta destinada al estudio de sistemas de Fe (II) que presentan el fenomeno de la transicion de espin a escala nanometrica. El capitulo 1 contiene una introduccion general sobre materiales moleculares multifuncionales, destacando aquellos ejemplos mas importantes. Por otro lado, se explicara el fenomeno de la transicion de espin, tratando aspectos conceptuales, los antecedentes mas importantes y la situacion actual. En el capitulo 2 se describen los diferentes procesos existentes para la obtencion de diferentes tipos de nanoparticulas. Ademas, se presenta la sintesis y caracterizacion de nanoparticulas del polimero de coordinacion unidimensional [Fe(Htrz)2(trz)]BF4, obtenidas mediante el metodo de micelas inversas. Estas nanoparticulas, con una estrecha distribucion de tamanos centrada alrededor de los 11 nm, presentan una transicion de espin muy abrupta, con un ancho ciclo de histeresis termica de unos 40K. En el capitulo 3 se describe el proceso de modificacion del tamano de las nanoparticulas descritas en el capitulo anterior, llevado a cabo variando la proporcion de surfactante/H2O en el medio. Ademas, con el objetivo de modificar las propiedades magneticas de las nanoparticulas obtenidas en el capitulo 2, se lleva a cabo la sintesis de nanoparticulas de polimeros de la misma familia del [Fe(Htrz)2(trz)]BF4. En concreto se sintetizaron 3 nuevos tipos de nanoparticulas basadas en el polimero [Fe(Htrz)1-x(NH2trz)x](ClO4)2, siendo x = 0.05, 0.15 y 0.3, en cada caso. Estas nanoparticulas siguen presentando una estrecha distribucion de tamanos y una transicion de espin muy abrupta y con un ancho ciclo de histeresis. Ademas, se observa que este ciclo se desplaza a temperaturas mas proximas a la temperatura ambiente a medida que se aumenta el porcentaje de 4-amino-1, 2, 4- triazol en la muestra. Pero al mismo tiempo se produce una disminucion de la anchura de este ciclo. Por ultimo, en este capitulo se presenta la

  11. PFI-ZEKE (Pulsed Field Ionization-Zero Electron Kinetic Energy) para el estudio de iones

    NASA Astrophysics Data System (ADS)

    Castaño, F.; Fernández, J. A.; Basterretxea, A. Longarte. F.; Sánchez Rayo, M. N.; Martínez, R.

    descubierta, que va en contra de lo esperado en otros sistemas físicos y que consiste en que los altos estados Rydberg de átomos, moléculas y sus complejos de van der Waals (o de los iones) tienen tiempos de vida de centenas de μ s. En resumen, el experimento y la espectroscopía ZEKE consiste en excitar un átomo, molécula o cluster sucesivamente a dos estados excitados selectivos de manera que el final sea un estado Rydberg. A continuación se aplica un campo eléctrico variable que lo ioniza y después de un cierto retraso se aplica un campo eléctrico de extracción, tanto para el electrón como para el ión. El espectro de los iones, es un espectro ZEKE. Hay varias alternativas para hacer este último proceso. El estudio de la espectroscopía y propiedades de iones y sus clusters requiere el conocimiento detallado de la espectroscopía de la molécula neutra, los estados Rydberg, de los confórmeros y sus complejos. Todo ello implica el haber estudiado los sistemas por LIF, REMPI y doble resonancia (hole burning IR-UV, UV-UV). Además solo es posible interpretar los resultados y obtener la información contenida en los espectros con ayuda de cálculos cuánticos ab initio. Hasta el momento hemos aplicado tanto el ZEKE como el conjunto de técnicas mencionadas anteriormente, a varias molécula de interés químico general como anilina y sus derivados, así como sus complejos con agua y amoniaco. Sin embargo, el método es muy versátil y puede aplicarse a iones de átomos, iones múltiples, moléculas sencillas y sus clusters así como a sus semi-reacciones. Como ejemplo de uno de estos espectros PFI-ZEKE se presenta aquí el caso del amonibenzonitrilo, ABN y solamente en su estado fundamental. En la conferencia se presentarán espectros ZEKE del ABN y moléculas similares en estados vibracionales intermedios (islas de estabilidad), así como la determinación de potenciales de ionización precisos, energías de enlace de compuestos del ión con varios disolventes y

  12. A novel compound heterozygous mutation (35delG, 363delC) in the Connexin 26 gene causes non-syndromic autosomal recessive hearing loss.

    PubMed

    Onsori, Habib; Rahmati, Mohammad; Fazli, Davood

    2014-01-01

    Mutations in the Connexin 26 (Cx26) gene are a common cause of hereditary hearing loss in different populations. In the present study, an Iranian patient with bilateral hearing loss underwent molecular analysis for the causative mutation. DNA studies were performed for the Cx26 gene by PCR and sequencing methods. We describe a novel compound heterozygous mutation (35delG, 363delC) in the Cx26 gene that is strongly associated with congenital non-syndromic hearing loss (NSHL).

  13. Aplicación del Teorema de Nekhorochev para tiempos de estabilidad en Mecánica Celeste

    NASA Astrophysics Data System (ADS)

    Miloni, O.; Núñez, J.; Brunini, A.

    En Mecánica Celeste, uno de los problemas centrales consiste en la determinación de los tiempos de estabilidad. El teorema de Nekhorochev proporciona un método para dicho estudio, para un sistema determinado por un hamiltoniano descripto en las variables acción-ángulo. El trabajo consiste en la acotación tanto del potencial perturbador y de la matriz hessiana del hamiltoniano integrable para determinar luego el tiempo de estabilidad de dicho sistema, donde por estabilidad se entiende la separación en norma infinito en el espacio de las acciones.

  14. Inventario mundial de la calidad del carbon mineral (WoCQI) [The world coal quality inventory (WoCQI)

    USGS Publications Warehouse

    Finkelman, R.B.; Lovern, V.S.

    2001-01-01

    Los oficiales encargados de la politica comercial de cada pais requieren informacion clara y precisa sobre el recurso del carbon mineral, particularmente sobre sus propiedades y caracteristicas, para tomar decisiones bien fundamentadas con respecto al mejor uso de los recursos naturales, necesidades de importacion y oportunidades de exportacion, objetivos de politica interna y externa, oportunidades de transferencia tecnologica, posibilidades de inversion externa, estudios ambientales y de salud, y asuntos relacionados con el uso de productos secundarios y su disposicion.

  15. Los plaguicidas y la contaminacion del medio ambiente Venezolano

    USGS Publications Warehouse

    Stickel, L.F.; Stickel, W.H.

    1972-01-01

    RESUMEN DE RECOMENDACIONES Recomendaciones para el Programa de Investigacion: 1. Establecer un sistema de muestreo biologico para detectar los niveles tendencias de los productos quimicos toxicos en un peque?o numero de si tios representativos. 2. Mantener continua vigilancia de la contaminacion ambiental, mediante la seleccion acertadamente dirigida de las zonas afectadas y de las fuentes de contaminacion. 3. Realizar estudios acerca de las poblaciones de animales silvestres, y del exito de los procesos reproductivos de las especies o grupos clayes de animales que se consideran mas gravemente afectados. 4. Preparar recomendaciones para una accion gubernamental de proteccion al hombre, a la fauna silvestre y al medio ambiente. Recomendaciones para la Accion Administrativa: 1. Establecer limites a la tolerancia de los residuos de plaguicidas en los alimentos. Constituye una medida clave para disminuir la contaminacion ambiental. 2. Establecer normas de calidad del agua para las corrientes, represas, la gos y otros cuerpos. Es la segunda medida clave para reducir la contaminacion del ambiente 3. Exigir un tratamiento adecuado de los efluentes industriales, especialmente antes de que se construyan las nuevas plantas. 4. Exigir a los agricultores que en el uso de plaguicidas sigan los consejos tecnicos autorizados y negar a los vendedores el derecho a recomendar productos por su cuenta. 5. Tomar medidas para recoger y eliminar los recipientes y sobrantes de los plaguicidas.

  16. Primeros resultados sobre el estudio de oscilaciones no radiales

    NASA Astrophysics Data System (ADS)

    Córsico, A.; Benvenuto, O. G.

    En el Observatorio de La Plata se ha comenzado a elaborar un código de pulsaciones el cual resuelve el problema de las oscilaciones no radiales en el caso adiabático. Dicho código está basado en la técnica de diferencias finitas ampliamente usado en cálculos de estructura y evolución estelar. En este trabajo se presentan los primeros resultados encontrados aplicando el código mencionado al caso de una polítropa de índice n=3. Se presentan los valores de las autofrecuencias y las autofunciones para diferentes modos de pulsación de dicha configuración politrópica. En un futuro próximo, se aplicará este programa al estudio de las pulsaciones no radiales de estrellas enanas blancas.

  17. Estudio polarimétrico de NGC 104 (47 Tucanae)

    NASA Astrophysics Data System (ADS)

    Forte, J. C.; Bassino, L. P.; Vega, E. I.; Cellone, S.; Pellizza, L.; Méndez, M.

    Se presentan observaciones polarimétricas en el Visual y sin filtro para 72 estrellas, 14 zonas de referencia y el núcleo del cúmulo globular NGC 104. Las medidas, hechas en el CASLEO con el nuevo polarimétro CASPROF, muestran un comportamiento complejo que incluye: a) dos componentes de polarización a lo largo de la visual; b) signos de envolturas polvorientas en 8 de 10 estrellas variables de largo período pertenecientes al cúmulo c) media docena de estrellas con alta polarización residual (P> 0.20 %) originada probablemente en scattering. Estas estrellas se encuentran próximas a una estructura extendida, coincidente con la región central del cúmulo, detectada en observaciones IRAS. Las observaciones son consistentes con la presencia de pequeñas cantidades de polvo originada en procesos de pérdida de masa.

  18. Molecular Spintronics

    NASA Astrophysics Data System (ADS)

    Sanvito, Stefano

    2010-03-01

    In organic molecules and molecular solids the weak spin-orbit and hyperfine interactions result in extremely long spin-lifetimes reaching up to the second mark. However the same are characterized by a generally poor mobility, so that the spin-diffusion lengths are rather short. These peculiar characteristics position organic molecules in a unique space within Spintronics and one should envision applications where the spins are manipulated close to where they are injected [1]. In this contribution I will review the current state of the art of the theory of spin-transport and manipulation in organic molecules. I will start the discussion by presenting a new mechanism, the electrostatic spin crossover effect, for manipulating electrically the magnetic state of a molecules without calling for current-driven spin-transfer torques [2]. This is based on the fact that the different spin states of a molecule Stark-shift differently and it is mostly effective when inversion symmetry is broken. Then I will move to discuss the consequences of such an effect on the transport properties of a molecule presenting two magnetic centers and demonstrate that there exist a critical voltage at which the current becomes temperature-independent [3]. Finally I will present results for spin-transport in Mn12 and demonstrate that the magnetic state of the molecule can be read electrically with a single I-V read-out obtained by using non-magnetic electrodes [4]. [4pt] [1] G. Szulczewski, S. Sanvito and J.M.D. Coey, Nature Materials 8, 693 (2009).[0pt] [2] N. Baadji, M. Piacenza, T. Tugsuz, F. Della Sala, G. Maruccio and S. Sanvito, Nature Materials 8, 813 (2009).[0pt] [3] S.K. Shukla and S. Sanvito, Phys. Rev. B, in press; also at arXiv:0905.1607.[0pt] [4] C.D. Pemmaraju, I. Rungger and S. Sanvito, Phys. Rev. B 80, 104422 (2009).

  19. Molecular Electronic Terms and Molecular Orbital Configurations.

    ERIC Educational Resources Information Center

    Mazo, R. M.

    1990-01-01

    Discussed are the molecular electronic terms which can arise from a given electronic configuration. Considered are simple cases, molecular states, direct products, closed shells, and open shells. Two examples are provided. (CW)

  20. The molecular matching problem

    NASA Technical Reports Server (NTRS)

    Kincaid, Rex K.

    1993-01-01

    Molecular chemistry contains many difficult optimization problems that have begun to attract the attention of optimizers in the Operations Research community. Problems including protein folding, molecular conformation, molecular similarity, and molecular matching have been addressed. Minimum energy conformations for simple molecular structures such as water clusters, Lennard-Jones microclusters, and short polypeptides have dominated the literature to date. However, a variety of interesting problems exist and we focus here on a molecular structure matching (MSM) problem.

  1. Aplicación de la metodología Molecular de Orbitales de Defecto Cuántico (MQDO) al cálculo de intensidades vibrónicas y vidas medias de niveles vibracionales

    NASA Astrophysics Data System (ADS)

    María Velasco Sanz, Ana

    Desde que se formuló, en 1996, la metodología Molecular de Orbitales de Defecto Cuántico (MQDO) [1], se han obtenido datos de calidad relativos a intensidades de bandas electrónicas que implican estados Rydberg para una gran variedad de sistemas moleculares [2]. Animados por los buenos resultados obtenidos, recientemente hemos abordado el estudio de transiciones vibrónicas, es decir aquellas que ocurren entre estados vibracionales que pertenecen a distintos estados Rydberg electrónicos. Como prototipo adecuado para nuestros propósitos hemos elegido la molécula de NO, importante en la química de la atmósfera, y para la cual existen en la bibliografía datos experimentales de calidad suficiente para contrastar la validez de nuestros resultados. En concreto, hemos calculado las fuerzas de oscilador y coeficientes de Einstein para transiciones electrónicas y vibrónicas de las principales bandas del NO, al igual que vidas medias radiativas de niveles vibracionales de dicha molécula. Las propiedades estudiadas son esenciales para la comprensión de los aspectos teóricos de los procesos físicos básicos relativos a la dispersión electrónica en moléculas heteronucleares con capas abiertas. Además, valores fiables de probabilidades de transición moleculares tienen importantes aplicaciones en Astrofísica, en la modelización de procesos fotodinámicos moleculares, etc., al igual que para evaluar más profundamente la validez de nuestra metodología teórica.

  2. Nevado del Huila, Columbia

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Nevado del Huila Volcano in Colombia is actually a volcanic chain running north to south, capped by a glacier. With peaks ranging in height from 2,600 to 5,780 meters (8,530 to 18,960 feet), Nevado del Huila is a stratovolcano composed of alternating layers of hardened lava, solidified ash, and volcanic rocks. Its first recorded eruption occurred in the mid-sixteenth century. The long-dormant volcano erupted again in mid-April 2007. A few months before the eruption, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of Nevado del Huila, on February 23, 2007. In this image, the bright white area just east of the central summit is ice. Immediately west of the summit are bare rocks, appearing as blue-gray. West of those rocks, white reappears, but this patch of white results from clouds hovering in the nearby valley. In the east, the colors turn to brown (indicating bare rock) and bright green (indicating vegetation). ASTER photographed Nevado del Huila near the end of a long phase of quietude. On April 17, 2007, local authorities recorded seismic activity associated with rock fracturing on the volcano's central summit, according to the ReliefWeb Website. Activity intensified the following day with an eruption and mudflows, forcing thousands of nearby residents to evacuate. As the Associated Press reported, the eruption caused avalanches and floods that wiped away both houses and bridges. It marked the volcano's first recorded eruption since the Spanish colonized the area five centuries earlier. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

  3. Percepcion Del Crimen Cibernetico y la Confianza en la Asignacion de Recursos Para Combatirlo: Un Estudio Multisectorial en Puerto Rico

    ERIC Educational Resources Information Center

    Rivera Vazquez, Juan C.

    2012-01-01

    Cyber crime is a term used to describe the abuse and misuse of a computer system where it is at a loss for someone across the world. It also refers to crimes committed by, or with computers via the Internet or only accessing a computer, is to steal or manipulate information of a company or a person and to use as a means for traditional such as…

  4. Influencia de diferentes ecuaciones de transformacion del sistema UBVal RGU en el estudio fotometrico de cumulos galacticos.

    NASA Astrophysics Data System (ADS)

    Huestamendia Aparicio, G.

    Three-colour photometry of ten open clusters in the RGU system has been carried out. The calibration sequence has been defined using the Buser's transformation equations between the UBV and RGU systems, while in earlier works the Steinlin's formulae have been used. The results have been compared with those given in these works. Some differences have been found in G, G-R and U-G as a function of the spectral type and the interstellar absorption. They have a systematic character.

  5. Estudio general de la region del Lago Titicaca evaluando en forma preliminar un sistema de analisis interactivo de imagenes multiespectrales

    USGS Publications Warehouse

    Brockmann, C.E.; Carter, William D.

    1976-01-01

    ERTS-1 digital data in the form of computer compatible tapes provide the geoscientist with an unusual opportunity to test the maximum flexibility of the satellite system using interactive computers, such as the General Electric Image 100 System. Approximately 9 hours of computer and operator time were used to analyze the Lake Titicaca image, 1443-14073, acquired 9 October 1973. The total area of the lake and associate wetlands was calculated and found to be within 3 percent of previous measurements. The area was subdivided by reflectance characteristics employing cluster analysis of all 4 bands and later compared with density values of band 4. Reflectance variations may be attributed to surface roughness, water depth and bottom characteristics, turbidity, and floating matter. Wetland marsh vegetation, vegetation related to ground-water effluents, natural grasses, and farm crops were separated by cluster analysis. Sandstone, limestone, sand dunes, and several volcanic rock types were similarly separated and displayed by assigned colors and extended through the entire scene. Waste dumps of the Matilde Zinc Mine and smaller mine workings were tentatively identified by signature analysis. Histograms of reflectance values and map printouts were automatically obtained as a record of each of the principal themes. These themes were also stored on a work tape for later display and photographic record as well as to serve in training. The Image 100 System is rapid, extremely flexible and very useful to the investigator in identifying subtle features that may not be noticed by conventional image analysis. The entire scene, which covers 34,225 km2, was analyzed at a scale of 1:600,000, and portions at 1:98,000 and 1:25,000, during a 9-hour period at a rental cost of $250 per hour. Costs to the user can be reduced by restricting its uses to specific areas, objectives, and procedures, rather than undertaking a complete analysis of a total scene.

  6. Caracterización del sistema fotométrico del VVV para el estudio de la subestructura en nuestra galaxia

    NASA Astrophysics Data System (ADS)

    Santucho, V.; Gurovich, S.; Dominguez, M.; Minniti, D.; Soto, M.; Amôres, E. B.

    In this work we calculate colour transformation equations between the VVV and 2MASS filters for bulge field stars. Our method involves matching stars from both surveys and include cuts to ensure that only sources with the best photometry are included in the calibration. Our bivariate weighted fits show that the transformation equations depend on galactic coordinates, so we provide local transformation calibrations, for each Tile. FULL TEXT IN SPANISH

  7. On molecular graph comparison.

    PubMed

    Melo, Jenny A; Daza, Edgar

    2011-06-01

    Since the last half of the nineteenth century, molecular graphs have been present in several branches of chemistry. When used for molecular structure representation, they have been compared after mapping the corresponding graphs into mathematical objects. However, direct molecular comparison of molecular graphs is a research field less explored. The goal of this mini-review is to show some distance and similarity coefficients which were proposed to directly compare molecular graphs or which could be useful to do so.

  8. Understanding molecular structure from molecular mechanics.

    PubMed

    Allinger, Norman L

    2011-04-01

    Molecular mechanics gives us a well known model of molecular structure. It is less widely recognized that valence bond theory gives us structures which offer a direct interpretation of molecular mechanics formulations and parameters. The electronic effects well-known in physical organic chemistry can be directly interpreted in terms of valence bond structures, and hence quantitatively calculated and understood. The basic theory is outlined in this paper, and examples of the effects, and their interpretation in illustrative examples is presented.

  9. Deficiency of developmental endothelial locus-1 (Del-1) aggravates bleomycin-induced pulmonary fibrosis in mice.

    PubMed

    Kang, Yoon-Young; Kim, Dong-Young; Lee, Seung-Hwan; Choi, Eun Young

    2014-03-07

    Pulmonary fibrosis is a lung disease wherein lung parenchyma is gradually and irreversibly replaced with collagen. The molecular pathogenesis of pulmonary fibrosis is not fully understood and the only effective treatment available is lung transplantation. To test if Del-1, an endogenous anti-inflammatory molecule, may be implicated in the development of pulmonary fibrosis, we induced pulmonary fibrosis in wild type (WT) and Del-1(-/-) mice by intratracheal administration of bleomycin. Del-1 expression in the lung was decreased in the WT mice treated with bleomycin compared to control mice. In addition, bleomycin-induced pulmonary fibrosis increased collagen deposition and TGF-β production in the lung of Del-1(-/-) mice. Finally, Del-1(-/-) mice treated with bleomycin displayed higher weight loss and greater mortality than did WT mice identically treated. These findings suggest that Del-1 may negatively regulate development of pulmonary fibrosis. Further delineation of a role for Del-1 in the development of pulmonary fibrosis will broaden our understanding of the molecular pathogenesis of this disease and hopefully help develop potential therapeutics.

  10. Molecular implementation of molecular shift register memories

    NASA Technical Reports Server (NTRS)

    Beratan, David N. (Inventor); Onuchic, Jose N. (Inventor)

    1991-01-01

    An electronic shift register memory (20) at the molecular level is described. The memory elements are based on a chain of electron transfer molecules (22) and the information is shifted by photoinduced (26) electron transfer reactions. Thus, multi-step sequences of charge transfer reactions are used to move charge with high efficiency down a molecular chain. The device integrates compositions of the invention onto a VLSI substrate (36), providing an example of a molecular electronic device which may be fabricated. Three energy level schemes, molecular implementation of these schemes, optical excitation strategies, charge amplification strategies, and error correction strategies are described.

  11. Estudio de la envoltura fría en presencia de un campo magnético en estrellas tempranas

    NASA Astrophysics Data System (ADS)

    Montero, M. F.; Platzeck, A. M.

    En el estudio de la distribución espacial de la densidad en torno a estrellas tempranas, al menos en dos coordenadas, se consideran en general ``escenarios" cualitativos. Existen sólo dos modelos calculados a partir de la ecuación de conservación de momento: el de Poeckert y Marlborough (Astroph. Journal 220, 940, 1978) y el de Ringuelet e Iglesias (Astroph. Journal 369, 463, 1991). El primero es isotermo considerando campo gravitatorio y fuerza centrífuga. El segundo, resuelve un caso no isotermo en equilibrio hidrostático teniendo en cuenta los campos gravitatorios, de radiación y magnético. En esta comunicación presentamos el análisis, que se deriva de los resultados de Ringuelet e Iglesias para el caso hidrostático, de la estructura de líneas de campo magnético. A continuación estudiamos la forma en que se modifica la distribución espacial de la densidad en la envoltura fría, cuando se tiene en cuenta el movimiento del plasma.

  12. Estudio de la influencia de la refrigeracion con aire de forma natural e inducida en el comportamiento de instalaciones fotovoltaicas

    NASA Astrophysics Data System (ADS)

    Mazon Hernandez, Rocio

    panels are analysed to compare and select the best configuration. The presented research provides a deep knowledge of how they work as well as information and results for an improvement in future designs of building integrated photovoltaic systems. Este estudio se centra en analizar la influencia negativa de la temperatura en la produccion electrica de paneles fotovoltaicos al estar emplazados sobre cubierta de acero, como sucede en naves industriales y sobre un invernadero. Se estudian diferentes configuraciones que permitan refrigerar los paneles, reduciendo su temperatura y mejorar su rendimiento. Para abordar este problema, se han construido dos instalaciones experimentales, fieles a plantas solares en funcionamiento. Una instalacion engloba dos paneles fotovoltaicos sobre estructura fija al suelo. Uno de los paneles esta integrado sobre una superficie paralela y metalica. Entre ambas superficies existe un espacio que posibilita circular aire, permitiendo refrigerar el panel por conveccion natural, o conveccion forzada impulsando el aire con un ventilador. El otro panel, libre por su cara posterior y se ha considerado de referencia. Se ha estudiado el comportamiento del panel integrado sobre cubierta para diferentes secciones de aire y velocidades inducidas, comparandolo con el panel de referencia. Se ha desarrollado un modelo experimental que nos permite determinar la temperatura del panel en funcion de las variables que influyen en su refrigeracion. Adicionalmente, se han analizado los datos de una planta solar en funcionamiento, con paneles de igual caracteristicas, obteniendo correlaciones entre la temperatura del panel y las variables electricas y comparandolos con las obtenidas en la instalacion experimental. La segunda instalacion experimental reproduce parte de una instalacion solar sobre un invernadero, formada por cuatro paneles fotovoltaicos colocados sobre el plastico del invernadero, existiendo un canal divergente entre ambas superficies. Se estudia la

  13. Molecular Epidemiology of Epidemic Severe Malaria Caused by Plasmodium vivax in the State of Amazonas, Brazil

    DTIC Science & Technology

    2005-01-01

    Suarez, C.F., Florez, C., del Portillo, H.A.; Andrade, L.E. Direct Submission to NCBI gene bank. Submitted 03-JAN-1997. Laboratorio de Biologia Molecular ...display a currently valid OMB control number. 1. REPORT DATE 2005 2. REPORT TYPE 3. DATES COVERED - 4. TITLE AND SUBTITLE Molecular ...statement The author hereby certifies that the use of any copyrighted material in the thesis manuscript entitled: “ Molecular Epidemiology of

  14. Estudio teórico de la desorción de Na y K de SiO2 estimulada por la acción de fotones o electrones

    NASA Astrophysics Data System (ADS)

    Domínguez Ariza, D.; López, N.; Illas, F.; Pacchioni, G.; Madey, T. E.

    Se ha estudiado el mecanismo de generación de sodio y potasio atómico a partir de muestras de SiO2 utilizando cálculos basados tanto en la teoría del funcional de la densidad como en métodos post-Hartree Fock, así como en el método de cluster para modelar el sólido. Como consecuencia del estudio se han propuesto distintos caminos posibles para la desorción, estimulada por la acción de fotones o electrones, de sodio y potasio desde el óxido de silicio, proporcionando por lo tanto una explicación a la atmósfera tenue de sodio y potasio de La Luna.

  15. Fotometría CCD en el campo del cúmulo abierto Ruprecht 58

    NASA Astrophysics Data System (ADS)

    Giorgi, E. E.; Vázquez, R. A.; Seggewiss, W.; Ostrov, P.; Solivella, G. R.

    La región de Vela-Puppis contiene varios cúmulos cuyo estudio puede brindarnos información acerca de la cinemática y el estado evolutivo de la población estelar en las zonas externas del disco galáctico. A través de observaciones CCD en los filtros UBV en el campo del cúmulo abierto Ruprecht 58 (α2000= 8h 14m 41s, δ2000=-31o 57'), se han determinado por primera vez los parámetros fundamentales de este cúmulo tales como distancia, enrojecimiento y edad. Se analiza también la estructura de su secuencia principal y la presencia de gigantes y binarias.

  16. [Programme review of somatropin deficit in pediatrics at the Hospital Universitario Virgen del Rocío].

    PubMed

    Lavaredas, A; de la Puerta, R; Álvarez del Vayo, C

    2013-01-01

    Objetivo: Elaborar una revisión del programa de déficit de somatropina aplicado en pediatría en el Hospital Universitario Virgen del Rocío, utilizando dos grupos de pacientes, los diagnosticados con déficit de esta hormona y los nacidos pequeños para edad gestacional, con la intención de evaluar su efectividad en el primer año de tratamiento. Método: Realización de un estudio retrospectivo de la cohorte de pacientes en tratamiento con la hormona del crecimiento bajo los diagnósticos mencionados, con metodología observacional y transversal, a los cuales se aplicó un análisis estadístico con el programa Statistical Package for Social Sciences®. Resultados: Tras inicio del tratamiento la velocidad de crecimiento y la talla aumentaron y la edad ósea se aproximó a la edad cronológica. En los dos grupos tratados, en el primer año de tratamiento fueron los pacientes del sexo femenino con edad comprendida entre los 0 a 12 años con déficit de la hormona del crecimiento que respondieron mejor a la terapéutica establecida. Conclusiones: Pudimos observar que el tratamiento instituido se presentó altamente efectivo en ambos grupos de pacientes, permitiendo obtener un aumento favorable de estatura.

  17. Del(15q) is a recurrent “minor route” cytogenetic abnormality in the clonal evolution of chronic myelogenous leukemia

    PubMed Central

    Yin, C. Cameron; Abruzzo, Lynne V.; Qiu, Xiaoyan; Apostolidou, Effrosyni; Cortes, Jorge E.; Medeiros, L. Jeffrey; Lu, Gary

    2014-01-01

    Del(15q) is known to occur in acute leukemias, but has been described rarely in chronic myelogenous leukemia (CML). We describe five cases of CML associated with del(15q). There were four men and one woman. Bone marrow aspirate smears demonstrated increased blasts in all cases at the time of del(15q) detection, showing accelerated phase in two and myeloid blast phase in three. Conventional cytogenetic analysis showed t(9;22) and del(15q), as well as other inconsistent clonal abnormalities. All patients received imatinib mesylate, four received additional chemotherapy, and two underwent allogeneic stem cell transplantation (ASCT). For the three patients who did not receive ASCT, one died, one was in persistent blast phase, and one was in clinical remission with molecular evidence of residual disease, 16, 6, and 34 months after identification of del(15q), respectively. For the two patients who underwent ASCT, one died and one was in clinical remission with molecular evidence of disease, 15 and 64 months after identification of del(15q), respectively. Our findings indicate that del(15q) is a recurrent cytogenetic abnormality that may be seen either at initial presentation of advanced disease or emerge during disease progression. Del(15q) appears to be associated with a poor prognosis in CML. PMID:19480932

  18. Comportamiento del Helio en estrellas químicamente peculiares

    NASA Astrophysics Data System (ADS)

    Malaroda, S. M.; López García, Z.; Leone, F.; Catalano, F.

    Las estrellas químicamente peculiares (CP) se caracterizan por tener deficiencias y sobreabundancias de algunos elementos químicos de hasta 106 veces la abundancia solar. Además presentan variaciones en las líneas espectrales. Se piensa que ello se debe a que los campos magnéticos presentes en este tipo de estrellas son principalmente dipolares, con un eje de simetría diferente del eje de rotación. La distribución de los elementos sobreabundantes y deficientes no es homogénea sobre la superficie estelar y las variaciones observadas serían una consecuencia directa de la rotación estelar. Entre los elementos con abundancia anómala se encuentra el Helio, cuyas líneas tienen intensidades que no son consistentes con una abundancia normal, que no puede ser determinada del modo usual, o sea, considerando una atmósfera con composición solar. Con el fin de determinar la abundancia de este elemento, se inició un estudio de estrellas anómalas de Helio, Hew y He strong. Además se determinarán las abundancias de otros elementos anómalos como ser el Si, Cr, Mg, Mn y Fe. Las mismas se determinan del modo tradicional, o sea: a) medida de los anchos equivalentes de las líneas de los distintos elementos analizados; b) adopción de la temperatura efectiva, gravedad y abundancia del Helio; c) cálculo del modelo de atmósfera d) comparación con las observaciones y reinicio de un proceso iterativo hasta lograr un acuerdo entre todos los parámetros analizados. Las observaciones se llevaron a cabo en el Complejo Astronómico El Leoncito. Se observaron setenta y ocho estrellas anómalas de Helio. En este momento se está procediendo a calcular las abundancias correspondientes a los distintos elementos químicos. Para ello se hace uso de los modelos de Kurucz, ATLAS9. Los cálculos NLTE de las líneas de Helio se llevan a cabo con el programa MULTI y se compararán con los realizados con el programa WIDTH9 de Kurucz (LTE), con el objeto de resaltar la importancia de

  19. Molecular similarity measures.

    PubMed

    Maggiora, Gerald M; Shanmugasundaram, Veerabahu

    2011-01-01

    Molecular similarity is a pervasive concept in chemistry. It is essential to many aspects of chemical reasoning and analysis and is perhaps the fundamental assumption underlying medicinal chemistry. Dissimilarity, the complement of similarity, also plays a major role in a growing number of applications of molecular diversity in combinatorial chemistry, high-throughput screening, and related fields. How molecular information is represented, called the representation problem, is important to the type of molecular similarity analysis (MSA) that can be carried out in any given situation. In this work, four types of mathematical structure are used to represent molecular information: sets, graphs, vectors, and functions. Molecular similarity is a pairwise relationship that induces structure into sets of molecules, giving rise to the concept of chemical space. Although all three concepts - molecular similarity, molecular representation, and chemical space - are treated in this chapter, the emphasis is on molecular similarity measures. Similarity measures, also called similarity coefficients or indices, are functions that map pairs of compatible molecular representations that are of the same mathematical form into real numbers usually, but not always, lying on the unit interval. This chapter presents a somewhat pedagogical discussion of many types of molecular similarity measures, their strengths and limitations, and their relationship to one another. An expanded account of the material on chemical spaces presented in the first edition of this book is also provided. It includes a discussion of the topography of activity landscapes and the role that activity cliffs in these landscapes play in structure-activity studies.

  20. Molecular similarity measures.

    PubMed

    Maggiora, Gerald M; Shanmugasundaram, Veerabahu

    2004-01-01

    Molecular similarity is a pervasive concept in chemistry. It is essential to many aspects of chemical reasoning and analysis and is perhaps the fundamental assumption underlying medicinal chemistry. Dissimilarity, the complement of similarity, also plays a major role in a growing number of applications of molecular diversity in combinatorial chemistry, high-throughput screening, and related fields. How molecular information is represented, called the representation problem, is important to the type of molecular similarity analysis (MSA) that can be carried out in any given situation. In this work, four types of mathematical structure are used to represent molecular information: sets, graphs, vectors, and functions. Molecular similarity is a pairwise relationship that induces structure into sets of molecules, giving rise to the concept of a chemistry space. Although all three concepts molecular similarity, molecular representation, and chemistry space are treated in this chapter, the emphasis is on molecular similarity measures. Similarity measures, also called similarity coefficients or indices, are functions that map pairs of compatible molecular representations, that is, representations of the same mathematical form, into real numbers usually, but not always, lying on the unit interval. This chapter presents a somewhat pedagogical discussion of many types of molecular similarity measures, their strengths and limitations, and their relationship to one another.

  1. Engineering molecular machines

    NASA Astrophysics Data System (ADS)

    Erman, Burak

    2016-04-01

    Biological molecular motors use chemical energy, mostly in the form of ATP hydrolysis, and convert it to mechanical energy. Correlated thermal fluctuations are essential for the function of a molecular machine and it is the hydrolysis of ATP that modifies the correlated fluctuations of the system. Correlations are consequences of the molecular architecture of the protein. The idea that synthetic molecular machines may be constructed by designing the proper molecular architecture is challenging. In their paper, Sarkar et al (2016 New J. Phys. 18 043006) propose a synthetic molecular motor based on the coarse grained elastic network model of proteins and show by numerical simulations that motor function is realized, ranging from deterministic to thermal, depending on temperature. This work opens up a new range of possibilities of molecular architecture based engine design.

  2. Workshop on molecular animation.

    PubMed

    Bromberg, Sarina; Chiu, Wah; Ferrin, Thomas E

    2010-10-13

    From February 25 to 26, 2010, in San Francisco, the Resource for Biocomputing, Visualization, and Informatics (RBVI) and the National Center for Macromolecular Imaging (NCMI) hosted a molecular animation workshop for 21 structural biologists, molecular animators, and creators of molecular visualization software. Molecular animation aims to visualize scientific understanding of biomolecular processes and structures. The primary goal of the workshop was to identify the necessary tools for producing high-quality molecular animations, understanding complex molecular and cellular structures, creating publication supplementary materials and conference presentations, and teaching science to students and the public. Another use of molecular animation emerged in the workshop: helping to focus scientific inquiry about the motions of molecules and enhancing informal communication within and between laboratories.

  3. Workshop on Molecular Animation

    PubMed Central

    Bromberg, Sarina; Chiu, Wah; Ferrin, Thomas E.

    2011-01-01

    Summary February 25–26, 2010, in San Francisco, the Resource for Biocomputing, Visualization and Informatics (RBVI) and the National Center for Macromolecular Imaging (NCMI) hosted a molecular animation workshop for 21 structural biologists, molecular animators, and creators of molecular visualization software. Molecular animation aims to visualize scientific understanding of biomolecular processes and structures. The primary goal of the workshop was to identify the necessary tools for: producing high quality molecular animations, understanding complex molecular and cellular structures, creating publication supplementary materials and conference presentations, and teaching science to students and the public. Another use of molecular animation emerged in the workshop: helping to focus scientific inquiry about the motions of molecules and enhancing informal communication within and between laboratories. PMID:20947014

  4. Case Study: del Amo Bioventing

    EPA Science Inventory

    The attached presentation discusses the fundamentals of bioventing in the vadose zone. The basics of bioventing are presented. The experience to date with the del Amo Superfund Site is presented as a case study.

  5. [Guideline for the assessment of clinical research proposals. Comisión Nacional de Investigación Científica del Instituto Mexicano del Seguro Social].

    PubMed

    Mejía-Aranguré, Juan Manuel; Grijalva-Otero, Israel; Majluf-Cruz, Abraham; Cruz-López, Miguel; Núñez-Enríquez, Juan Carlos; Salamanca-Gómez, Fabio Abdiel

    2013-01-01

    Antecedentes: la investigación médica es una herramienta fundamental para lograr el avance de la ciencia al mejorar las acciones encaminadas a proteger, promover y restaurar la salud del individuo y de la sociedad en general. Las tres características imprescindibles para que un protocolo de investigación sea autorizado son: relevancia científica, calidad técnica y el cumplimiento de los aspectos éticos. Material y métodos: estudio retrospectivo efectuado con base en la búsqueda específica en Pubmed, Medline, Ovid y Google Scholar con los términos: peer review, research proposals, review and protocols and reviewers. Debido a que no se identificó ningún artículo que refiriera específicamente los criterios para evaluar protocolos de investigación clínica, se hizo un consenso entre los vocales de la Comisión Nacional de Investigación Científica del Instituto Mexicano del Seguro Social, que está integrada por investigadores titulares de la institución, todos pertenecientes al Sistema Nacional de Investigadores. Se discutieron los criterios que debieran componer una revisión adecuada y cuáles debieran ser los rubros que deben incluirse en el análisis. Resultados: se integraron los criterios específicos que le permitirán al revisor de un protocolo de investigación realizar una crítica con bases metodológicas aceptadas por un consenso de investigadores. Conclusiones: un revisor debe ser considerado como un promotor del avance del conocimiento científico que, mediante sus comentarios y su dictamen, permite que los investigadores incrementen la calidad de sus protocolos de investigación.

  6. Estudio epidemiológico de sucesos traumáticos, trastorno de estrés post-traumático y otros trastornos psiquiátricos en una muestra representativa de Chile

    PubMed Central

    Pérez Benítez, Carlos I.; Vicente, Benjamin; Zlotnick, Caron; Kohn, Robert; Johnson, Jennifer; Valdivia, Sandra; Rioseco, Pedro

    2010-01-01

    RESUMEN Durante la década de 1990 en los Estados Unidos (EU), el conocimiento sobre el trastorno de estrés post-traumático (TEPT) evolucionó de estudios específicos en un principio, sobre veteranos de guerra y sobre víctimas de desastres, a estudios epidemiológicos más tarde, sin embargo, la epidemiología del TEPT en países en desarrollo ha sido un área poco estudiada hasta ahora. Los expertos en el área de trauma han propuesto que los sucesos traumáticos que ocurren en la niñez son más perjudiciales para la salud mental que aquellos que ocurren más tarde en la vida. Este trabajo revisa los resultados de un estudio epidemiológico llevado a cabo en Chile. Específicamente, se revisan los resultados sobre las tasas de prevalencia del TEPT, traumas asociados más frecuentemente con él, así como la comorbilidad de este trastorno con otros trastornos psiquiátricos a lo largo de la vida. Igualmente se analizaron las diferencias del TEPT en cada sexo, así como la exposición a traumas en una muestra representativa de chilenos. Además se comparó la prevalencia de trastornos psiquiátricos en personas que sufrieron su primer trauma durante la niñez, durante la edad adulta, o que no reportaron traumas durante su vida. En estos estudios epidemiológicos se usaron módulos del TEPT y trastorno de personalidad antisocial (TPA) de la entrevista diagnóstica siguiendo los criterios del DSM-III-R (DIS–III-R). Para evaluar el resto de los trastornos psiquiátricos se usó la Entrevista Diagnóstica Internacional Compuesta (CIDI). Estos instrumentos fueron administrados en tres ciudades chilenas a 2390 personas mayores de 15 años. Para estimar los errores estándares (EE) debido al diseño de la muestra y a la necesidad de ajuste se usó el método Taylor de linearización seriada. También se usó un análisis de regresión logística para examinar la relación entre el TEPT, los factores demográficos de riesgo y el tipo de trauma. Además se utilizó la

  7. Molecular modelling and molecular dynamics of CFTR.

    PubMed

    Callebaut, Isabelle; Hoffmann, Brice; Lehn, Pierre; Mornon, Jean-Paul

    2017-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) protein is a member of the ATP-binding cassette (ABC) transporter superfamily that functions as an ATP-gated channel. Considerable progress has been made over the last years in the understanding of the molecular basis of the CFTR functions, as well as dysfunctions causing the common genetic disease cystic fibrosis (CF). This review provides a global overview of the theoretical studies that have been performed so far, especially molecular modelling and molecular dynamics (MD) simulations. A special emphasis is placed on the CFTR-specific evolution of an ABC transporter framework towards a channel function, as well as on the understanding of the effects of disease-causing mutations and their specific modulation. This in silico work should help structure-based drug discovery and design, with a view to develop CFTR-specific pharmacotherapeutic approaches for the treatment of CF in the context of precision medicine.

  8. Atomic and molecular supernovae

    NASA Technical Reports Server (NTRS)

    Liu, Weihong

    1997-01-01

    Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

  9. Cirugía de los trastornos del comportamiento: el estado del arte

    PubMed Central

    Yampolsky, Claudio; Bendersky, Damián

    2014-01-01

    Introducción: La cirugía de los trastornos del comportamiento (CTC) se está convirtiendo en un tratamiento más común desde el desarrollo de la neuromodulación. Métodos: Este artículo es una revisión no sistemática de la historia, indicaciones actuales, técnicas y blancos quirúrgicos de la CTC. Dividimos su historia en 3 eras: la primera comienza en los inicios de la psicocirugía y termina con el desarrollo de las tícnicas estereotácticas, cuando comienza la segunda era. Ésta se caracteriza por la realización de lesiones estereotácticas. Nos encontramos transitando la tercera era, que comienza cuando la estimulación cerebral profunda (ECP) comienza a ser usada en CTC. Resultados: A pesar de los errores graves cometidos en el pasado, hoy en día, la CTC está renaciendo. Los trastornos psiquiátricos que se más frecuentemente se tratan con cirugía son: depresión refractaria, trastorno obsesivo-compulsivo y síndrome de Tourette. Además, algunos pacientes con agresividad fueron tratados quirúrgicamente. Hay varios blancos estereotácticos descriptos para estos trastornos. La estimulación vagal puede ser usada también para depresión. Conclusión: Los resultados de la ECP en estos trastornos parecen alentadores. Sin embargo, se necesitan más estudios randomizados para establecer la efectividad de la CTC. Debe tenerse en cuenta que una apropiada selección de pacientes nos ayudará a realizar un procedimiento más seguro así como también a lograr mejores resultados quirúrgicos, conduciendo a la CTC a ser más aceptada por psiquiatras, pacientes y sus familias. Se necesita mayor investigación en varios temas como: fisiopatología de los trastornos del comportamiento, indicaciones de CTC y nuevos blancos quirúrgicos. PMID:25165612

  10. El libro del Relogio del Palacio de las Horas

    NASA Astrophysics Data System (ADS)

    Morales, J. D.

    2009-08-01

    This paper resume the investigation entitled ``El libro del Relogio del Palacio de las Horas''. That consist in an edition of the original text of the book of the Clock of the Palace of the Hours from the Books of the knowledge of Astronomy of Alfonso X (Manuscript 156, Complutense University). And a description of the astronomical functionality of the Clock of the Palace of the Hours. It includes a geometric description of the positional astronomy on which the operation of the Palace is based.

  11. Open Source Molecular Modeling

    PubMed Central

    Pirhadi, Somayeh; Sunseri, Jocelyn; Koes, David Ryan

    2016-01-01

    The success of molecular modeling and computational chemistry efforts are, by definition, dependent on quality software applications. Open source software development provides many advantages to users of modeling applications, not the least of which is that the software is free and completely extendable. In this review we categorize, enumerate, and describe available open source software packages for molecular modeling and computational chemistry. PMID:27631126

  12. Molecular Typing and Differentiation

    EPA Science Inventory

    In this chapter, general background and bench protocols are provided for a number of molecular typing techniques in common use today. Methods for the molecular typing and differentiation of microorganisms began to be widely adopted following the development of the polymerase chai...

  13. Interstellar molecular clouds.

    PubMed

    Bally, J

    1986-04-11

    The interstellar medium in our galaxy contains matter in a variety of states ranging from hot plasma to cold and dusty molecular gas. The molecular phase consists of giant clouds, which are the largest gravitationally bound objects in the galaxy, the primary reservoir of material for the ongoing birth of new stars, and the medium regulating the evolution of galactic disks.

  14. Molecular imaging in endoscopy

    PubMed Central

    Hoetker, Michael S

    2013-01-01

    Molecular imaging focuses on the molecular signature of cells rather than morphological changes in the tissue. The need for this novel type of imaging arises from the often difficult detection and characterization especially of small and/or premalignant lesions. Molecular imaging specifically visualizes biological properties of a lesion and might thereby be able to close diagnostic gaps, e.g. when differentiating hyperplastic from neoplastic polyps or detecting the margins of intraepithelial neoplastic spread. Additionally, not only the detection and discrimination of lesions could be improved: based on the molecular features identified using molecular imaging, therapy regimens could be adjusted on the day of diagnosis to allow for personalized medicine and optimized care for each individual patient. PMID:24917945

  15. Multifunctionality in molecular magnetism.

    PubMed

    Pinkowicz, Dawid; Czarnecki, Bernard; Reczyński, Mateusz; Arczyński, Mirosław

    2015-01-01

    Molecular magnetism draws from the fundamental ideas of structural chemistry and combines them with experimental physics resulting in one of the highest profile current topics, namely molecular materials that exhibit multifunctionality. Recent advances in the design of new generations of multifunctional molecular magnets that retain the functions of the building blocks and exhibit non-trivial magnetic properties at higher temperatures provide promising evidence that they may be useful for the future construction of nanoscale devices. This article is not a complete review but is rather an introduction into thefascinating world of multifunctional solids with magnetism as the leitmotif. We provide a subjective selection and discussion of the most inspiring examples of multifunctional molecular magnets: magnetic sponges, guest-responsive magnets, molecular magnets with ionic conductivity, photomagnets and non-centrosymmetric and chiral magnets.

  16. Crystalline molecular flasks.

    PubMed

    Inokuma, Yasuhide; Kawano, Masaki; Fujita, Makoto

    2011-05-01

    A variety of host compounds have been used as molecular-scale reaction vessels, protecting guests from their environment or restricting the space available around them, thus favouring particular reactions. Such molecular 'flasks' can endow guest molecules with reactivities that differ from those in bulk solvents. Here, we extend this concept to crystalline molecular flasks, solid-state crystalline networks with pores within which pseudo-solution-state reactions can take place. As the guest molecules can spontaneously align along the walls and channels of the hosts, structural changes in the substrates can be directly observed by in situ X-ray crystallography during reaction. Recently, this has enabled observation of the molecular structures of transient intermediates and other labile species, in the form of sequential structural snapshots of the chemical transformation. Here, we describe the principles, development and applications of crystalline molecular flasks.

  17. Determinación del perfil instrumental del EBASIM

    NASA Astrophysics Data System (ADS)

    Nieva, M. F.; Rodriguez, M. V.; Pintado, O. I.

    Se calcula el perfil instrumental para el telescopio de 2,15m del CASLEO con EBASIM. Para ello se usaron flats de cielo y el espectro solar FTS de Kurucz. El método, que se puede utilizar para otras configuraciones instrumentales, es convolucionar ambos espectros para obtener los coeficientes de corrección.

  18. Molecular Population Genetics

    PubMed Central

    Casillas, Sònia; Barbadilla, Antonio

    2017-01-01

    Molecular population genetics aims to explain genetic variation and molecular evolution from population genetics principles. The field was born 50 years ago with the first measures of genetic variation in allozyme loci, continued with the nucleotide sequencing era, and is currently in the era of population genomics. During this period, molecular population genetics has been revolutionized by progress in data acquisition and theoretical developments. The conceptual elegance of the neutral theory of molecular evolution or the footprint carved by natural selection on the patterns of genetic variation are two examples of the vast number of inspiring findings of population genetics research. Since the inception of the field, Drosophila has been the prominent model species: molecular variation in populations was first described in Drosophila and most of the population genetics hypotheses were tested in Drosophila species. In this review, we describe the main concepts, methods, and landmarks of molecular population genetics, using the Drosophila model as a reference. We describe the different genetic data sets made available by advances in molecular technologies, and the theoretical developments fostered by these data. Finally, we review the results and new insights provided by the population genomics approach, and conclude by enumerating challenges and new lines of inquiry posed by increasingly large population scale sequence data. PMID:28270526

  19. Molecular Population Genetics.

    PubMed

    Casillas, Sònia; Barbadilla, Antonio

    2017-03-01

    Molecular population genetics aims to explain genetic variation and molecular evolution from population genetics principles. The field was born 50 years ago with the first measures of genetic variation in allozyme loci, continued with the nucleotide sequencing era, and is currently in the era of population genomics. During this period, molecular population genetics has been revolutionized by progress in data acquisition and theoretical developments. The conceptual elegance of the neutral theory of molecular evolution or the footprint carved by natural selection on the patterns of genetic variation are two examples of the vast number of inspiring findings of population genetics research. Since the inception of the field, Drosophila has been the prominent model species: molecular variation in populations was first described in Drosophila and most of the population genetics hypotheses were tested in Drosophila species. In this review, we describe the main concepts, methods, and landmarks of molecular population genetics, using the Drosophila model as a reference. We describe the different genetic data sets made available by advances in molecular technologies, and the theoretical developments fostered by these data. Finally, we review the results and new insights provided by the population genomics approach, and conclude by enumerating challenges and new lines of inquiry posed by increasingly large population scale sequence data.

  20. EDITORIAL: Molecular Imaging Technology

    NASA Astrophysics Data System (ADS)

    Asai, Keisuke; Okamoto, Koji

    2006-06-01

    'Molecular Imaging Technology' focuses on image-based techniques using nanoscale molecules as sensor probes to measure spatial variations of various species (molecular oxygen, singlet oxygen, carbon dioxide, nitric monoxide, etc) and physical properties (pressure, temperature, skin friction, velocity, mechanical stress, etc). This special feature, starting on page 1237, contains selected papers from The International Workshop on Molecular Imaging for Interdisciplinary Research, sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) in Japan, which was held at the Sendai Mediatheque, Sendai, Japan, on 8 9 November 2004. The workshop was held as a sequel to the MOSAIC International Workshop that was held in Tokyo in 2003, to summarize the outcome of the 'MOSAIC Project', a five-year interdisciplinary project supported by Techno-Infrastructure Program, the Special Coordination Fund for Promotion of Science Technology to develop molecular sensor technology for aero-thermodynamic research. The workshop focused on molecular imaging technology and its applications to interdisciplinary research areas. More than 110 people attended this workshop from various research fields such as aerospace engineering, automotive engineering, radiotechnology, fluid dynamics, bio-science/engineering and medical engineering. The purpose of this workshop is to stimulate intermixing of these interdisciplinary fields for further development of molecular sensor and imaging technology. It is our pleasure to publish the seven papers selected from our workshop as a special feature in Measurement and Science Technology. We will be happy if this issue inspires people to explore the future direction of molecular imaging technology for interdisciplinary research.

  1. Molecular gearing systems

    SciTech Connect

    Gakh, Andrei A.; Sachleben, Richard A.; Bryan, Jeff C.

    1997-11-01

    The race to create smaller devices is fueling much of the research in electronics. The competition has intensified with the advent of microelectromechanical systems (MEMS), in which miniaturization is already reaching the dimensional limits imposed by physics of current lithographic techniques. Also, in the realm of biochemistry, evidence is accumulating that certain enzyme complexes are capable of very sophisticated modes of motion. Complex synergistic biochemical complexes driven by sophisticated biomechanical processes are quite common. Their biochemical functions are based on the interplay of mechanical and chemical processes, including allosteric effects. In addition, the complexity of this interplay far exceeds that of typical chemical reactions. Understanding the behavior of artificial molecular devices as well as complex natural molecular biomechanical systems is difficult. Fortunately, the problem can be successfully resolved by direct molecular engineering of simple molecular systems that can mimic desired mechanical or electronic devices. These molecular systems are called technomimetics (the name is derived, by analogy, from biomimetics). Several classes of molecular systems that can mimic mechanical, electronic, or other features of macroscopic devices have been successfully synthesized by conventional chemical methods during the past two decades. In this article we discuss only one class of such model devices: molecular gearing systems.

  2. Molecular gearing systems

    DOE PAGES

    Gakh, Andrei A.; Sachleben, Richard A.; Bryan, Jeff C.

    1997-11-01

    The race to create smaller devices is fueling much of the research in electronics. The competition has intensified with the advent of microelectromechanical systems (MEMS), in which miniaturization is already reaching the dimensional limits imposed by physics of current lithographic techniques. Also, in the realm of biochemistry, evidence is accumulating that certain enzyme complexes are capable of very sophisticated modes of motion. Complex synergistic biochemical complexes driven by sophisticated biomechanical processes are quite common. Their biochemical functions are based on the interplay of mechanical and chemical processes, including allosteric effects. In addition, the complexity of this interplay far exceeds thatmore » of typical chemical reactions. Understanding the behavior of artificial molecular devices as well as complex natural molecular biomechanical systems is difficult. Fortunately, the problem can be successfully resolved by direct molecular engineering of simple molecular systems that can mimic desired mechanical or electronic devices. These molecular systems are called technomimetics (the name is derived, by analogy, from biomimetics). Several classes of molecular systems that can mimic mechanical, electronic, or other features of macroscopic devices have been successfully synthesized by conventional chemical methods during the past two decades. In this article we discuss only one class of such model devices: molecular gearing systems.« less

  3. Molecular shape sorting using molecular organic cages.

    PubMed

    Mitra, Tamoghna; Jelfs, Kim E; Schmidtmann, Marc; Ahmed, Adham; Chong, Samantha Y; Adams, Dave J; Cooper, Andrew I

    2013-04-01

    The energy-efficient separation of chemical feedstocks is a major sustainability challenge. Porous extended frameworks such as zeolites or metal-organic frameworks are one potential solution to this problem. Here, we show that organic molecules, rather than frameworks, can separate other organic molecules by size and shape. A molecular organic cage is shown to separate a common aromatic feedstock (mesitylene) from its structural isomer (4-ethyltoluene) with an unprecedented perfect specificity for the latter. This specificity stems from the structure of the intrinsically porous cage molecule, which is itself synthesized from a derivative of mesitylene. In other words, crystalline organic molecules are used to separate other organic molecules. The specificity is defined by the cage structure alone, so this solid-state 'shape sorting' is, uniquely, mirrored for cage molecules in solution. The behaviour can be understood from a combination of atomistic simulations for individual cage molecules and solid-state molecular dynamics simulations.

  4. Potential molecular wires and molecular alligator clips

    NASA Astrophysics Data System (ADS)

    Schumm, Jeffry S.; Pearson, Darren L.; Jones, LeRoy, II; Hara, Ryuichiro; Tour, James M.

    1996-12-01

    The synthesis of oligo(2-ethylphenylene-ethynylene)s, oligo(2-(0957-4484/7/4/023/img1-ethylheptyl)phenylene-ethynylene)s, and oligo(3-ethylthiophene-ethynylene)s is described via an iterative divergent convergent approach. Synthesized were the monomer, dimer, tetramer, octamer and 16-mer of the oligo(3-ethylthiophene-ethynylene)s and oligo(2-0957-4484/7/4/023/img1-ethylheptyl)phenylene-ethynylene)s. The 16-mers are 100 Å and 128 Å long, respectively. At each stage in the iteration, the length of the framework doubles. Only three sets of reaction conditions are needed for the entire iterative synthetic sequence; an iodination, a protodesilylation, and a Pd/Cu-catalyzed cross coupling. The oligomers were characterized spectroscopically and by mass spectrometry. The optical properties are presented which show the stage of optical absorbance saturation. The size exclusion chromatography values for the number average weights, relative to polystyrene, illustrate the tremendous differences in the hydrodynamic volume of these rigid rod oligomers versus the random coils of polystyrene. These differences become quite apparent at the octamer stage. The preparation of thiol-protected end groups is described. These may serve as molecular alligator clips for adhesion to gold surfaces. These oligomers may act as molecular wires in molecular electronic devices and they also serve as useful models for understanding related bulk polymers.

  5. Estudio de la formación de galaxias espirales en un modelo de agregación jerárquica

    NASA Astrophysics Data System (ADS)

    Tissera, P.; Saiz, A.; Dominguez-Tenreiro, R.

    El estudio de formación de galaxias espirales ha llevado al desarrollo de numerosos modelos teóricos (e.g. White & Rees 1978). En la actualidad, el modelo más aceptado predice la formación de una galaxia espiral a partir del colapso disipativo del gas en el pozo de potencial de un halo oscuro, conservando su momento angular específco (Fall & Efstathiou 1980). En los últimos años, ha sido posible realizar simulaciones numéricas hidrodinámicas, las cuales describen la evolución conjunta de la materia oscura y los bariones. Estos experimentos han señalado la dificultad de formar estructuras discoidales con propiedades consistentes con las observaciones, en modelos de agregación jerárquica. El problema principal se origina en la pérdida catastrófica de momento angular de la componente disipativa, durante el proceso de ensamblaje de los objetos, a través de la fusión de subestructura (Navarro & Steinmetz 1997). Estos experimentos no incluían procesos de formación estelar. En este trabajo, se expondrán resultados de simulaciones hidrodinámicas cosmológicas, incluyendo formación estelar (Tissera et al 1997), donde ha sido posible reproducir objetos discoidales con contrapartida observacional. El elemento fundamental ha sido la formación de bulbos estelares, los cuales han evitado la pérdida catastrófica de momento angular de los bariones. Se encontró que los discos exponenciales puramente gaseosos son altamente inestables y suceptibles de generar barras, responsables de la pérdida de momento angular y la caída violenta del gas hacia la región central. Estas inestabilidades son fácilmente inducidas durante interacciones y fusiones con objetos vecinos (Barnes & Hernquist 1996). Un bulbo estelar (o un objeto masivo y compacto) estabiliza el disco ante perturbaciones externas, asegurándole un potencial simétrico (Sellwood & Moore 1998, Van der Bosch 1998). En este caso, el gas en el disco no pierde completamente su momento angular intr

  6. Molecularly Imprinted Membranes

    PubMed Central

    Trotta, Francesco; Biasizzo, Miriam; Caldera, Fabrizio

    2012-01-01

    Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40–50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that molecular imprinted membranes (i.e., polymer thin films) that show recognition properties at molecular level of the template molecule are used in their formation. Different procedures and potential application in separation processes and catalysis are reported. The influences of different parameters on the discrimination abilities are also discussed. PMID:24958291

  7. [Molecular diagnostics in neuropathology].

    PubMed

    Dietmaier, W; Lorenz, J; Riemenschneider, M J

    2015-03-01

    As in only few other areas of oncology, molecular markers in neurooncology have become an integral part of clinical decision-making. This development is driven by a bustling scientific activity exploring the molecular basis and pathogenesis of human brain tumors. In addition, a high percentage of brain tumor patients are included in clinical studies in which molecular markers are assessed and linked with clinical informativeness. First steps towards more differentiated therapeutic strategies against brain tumors have thus been taken. The implementation in the clinical and diagnostic routine requires a detailed knowledge and a close collaboration between all medical disciplines involved.

  8. Molecularly imprinted membranes.

    PubMed

    Trotta, Francesco; Biasizzo, Miriam; Caldera, Fabrizio

    2012-07-19

    Although the roots of molecularly imprinted polymers lie in the beginning of 1930s in the past century, they have had an exponential growth only 40-50 years later by the works of Wulff and especially by Mosbach. More recently, it was also proved that molecular imprinted membranes (i.e., polymer thin films) that show recognition properties at molecular level of the template molecule are used in their formation. Different procedures and potential application in separation processes and catalysis are reported. The influences of different parameters on the discrimination abilities are also discussed.

  9. Evaluacion de los recursos potenciales del petroleo y gas, en Centro y Suramerica [Evaluation of potential petroleum and gas resources in Central and South America

    USGS Publications Warehouse

    Schenk, C.S.

    2001-01-01

    El Servicio Geológico de los Estados Unidos (USGS, por sus siglas en inglés) completó recientemente un estudio evaluativo de recursos potenciales de petróleo y gas en 130 provincias de petróleo seleccionadas en diferentes partes del mundo (USGS, 2000). De estas 130 provincias, 23 se encuentran en Suramérica, Centroamérica, y la región del Caribe (fig. 1). El estudio comprendió desde las provincias de petróleo establecidas con un largo historial de producción, como la Cuenca de Maracaibo, hasta las provincias fronterizas de poca o ninguna producción, como la Cuenca de Guyana-Suriname. No todas las provincias con historial de producción o con potencial de producción fueron evaluadas en el Estudio Evaluativo USGS 2000. Al presente, el USGS está evaluando muchas de las provincias restantes de petróleo y gas, en Centro y Suramérica. En cada provincia hemos (1) definido geológicamente el total de los sistemas de petróleo, (2) definido las unidades evaluadas que forman parte de todos los sistemas de petróleo, y (3) evaluado el volumen potencial de petróleo y gas convencional en cada unidad evaluada. Definimos un total de 26 sistemas de petróleo y 55 unidades evaluadas en las 23 provincias

  10. Molecular Machines: Nanoscale gadgets

    NASA Astrophysics Data System (ADS)

    Garcia-Garibay, Miguel A.

    2008-06-01

    Meeting their biological counterparts halfway, artificial molecular machines embedded in liquid crystals, crystalline solids and mesoporous materials are poised to meet the demands of the next generation of functional materials.

  11. Are there molecular signatures?

    SciTech Connect

    Bennett, W.P.

    1995-10-01

    This report describes molecular signatures and mutational spectrum analysis. The mutation spectrum is defined as the type and location of DNA base change. There are currently about five well documented cases. Mutations and radon-associated tumors are discussed.

  12. Atomic & Molecular Interactions

    SciTech Connect

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  13. Natural Product Molecular Fossils.

    PubMed

    Falk, Heinz; Wolkenstein, Klaus

    2017-01-01

    The natural products synthesized by organisms that were living a long time ago gave rise to their molecular fossils. These can consist of either the original unchanged compounds or they may undergo peripheral transformations in which their skeletons remain intact. In cases when molecular fossils can be traced to their organismic source, they are termed "geological biomarkers".This contribution describes apolar and polar molecular fossils and, in particular biomarkers, along the lines usually followed in organic chemistry textbooks, and points to their bioprecursors when available. Thus, the apolar compounds are divided in linear and branched alkanes followed by alicyclic compounds and aromatic and heterocyclic molecules, and, in particular, the geoporphyrins. The polar molecular fossils contain as functional groups or constituent units ethers, alcohols, phenols, carbonyl groups, flavonoids, quinones, and acids, or are polymers like kerogen, amber, melanin, proteins, or nucleic acids. The final sections discuss the methodology used and the fundamental processes encountered by the biomolecules described, including diagenesis, catagenesis, and metagenesis.

  14. Nonequilibrium molecular dynamics

    SciTech Connect

    Hoover, W.G. . Dept. of Applied Science Lawrence Livermore National Lab., CA )

    1990-11-01

    The development of nonequilibrium molecular dynamics is described, with emphasis on massively-parallel simulations involving the motion of millions, soon to be billions, of atoms. Corresponding continuum simulations are also discussed. 14 refs., 8 figs.

  15. Mistakes and Molecular Evolution.

    ERIC Educational Resources Information Center

    Trevors, J. T.

    1998-01-01

    Examines the role mistakes play in the molecular evolution of bacteria. Discusses the interacting physical, chemical, and biological factors that cause changes in DNA and play a role in prokaryotic evolution. (DDR)

  16. Molecular Motors from DNA

    NASA Astrophysics Data System (ADS)

    Turberfield, Andrew

    2013-03-01

    DNA is a wonderful material for nanoscale construction: its self-assembly can be programmed by making use of its information-carrying capability and its hybridization or hydrolysis can be used as to provide energy for synthetic molecular machinery. With DNA it is possible to design and build three-dimensional scaffolds, to attach molecular components to them with sub-nanometre precision-and then to make them move. I shall describe our work on autonomous, biomimetic molecular motors powered by chemical fuels and the use of synthetic molecular machinery to control covalent chemical synthesis. I shall demonstrate bipedal motors whose operation depends on the coordination of the chemomechanical cycles of two separate catalytic centres and burnt bridges motors that can be programmed to navigate networks of tracks. I shall also discuss the use of kinesin motor proteins to power synthetic devices.

  17. [Molecular diagnostics in pathology].

    PubMed

    Stenzinger, A; Penzel, R; Endris, V; Weichert, W

    2013-05-01

    Tissue-based molecular diagnostics is a fast growing diagnostic field, which already complements morphologic classifications in many cases. Pathology based molecular diagnosis is performed almost exclusively on paraffin embedded material and always in conjunction with histopathology. Besides the classic field of tissue based detection of pathogenic organisms such as bacteria, viruses and fungi, molecular diagnostics of tumor tissue is one of the current hot topics in oncology. In this context the detection of predictive molecular biomarkers, such as specific mutations, allows patient stratification for individually tailored treatment strategies and thereby is one of the key components of individualized patient care in oncology. The rapidly growing number of clinically relevant predictive biomarkers together with impressive technical advances, specifically the development of massive parallel sequencing, will modify the care of patients with malignant diseases. Pathology, therefore, has returned in the very center of interdisciplinary patient care.

  18. Nearby Molecular Hydrogen

    NASA Technical Reports Server (NTRS)

    Lebrun, F.

    1984-01-01

    If the gas-to-dust ratio is sufficiently uniform throughout the local interstellar medium, galaxy counts may provide a useful probe of the large scale structure of the interstellar gas. This idea substantiated by gamma ray observations led to the discovery of nearby molecular cloud complexes. The reddening studies indicate that one of them lies between 80 and 140 pc from the Sun. From CO observations, its molecular mass is estimated to be a few 1000 stellar mass units.

  19. Introductory molecular genetics

    SciTech Connect

    Edwards-Moulds, J.

    1986-01-01

    This book begins with an overview of the current principles of genetics and molecular genetics. Over this foundation, it adds detailed and specialized information: a description of the translation, transcription, expression and regulation of DNA and RNA; a description of the manipulation of genetic material via promoters, enhancers, and gene splicing; and a description of cloning techniques, especially those for blood group genes. The last chapter looks to the impact of molecular genetics on transfusion medicine.

  20. Open source molecular modeling.

    PubMed

    Pirhadi, Somayeh; Sunseri, Jocelyn; Koes, David Ryan

    2016-09-01

    The success of molecular modeling and computational chemistry efforts are, by definition, dependent on quality software applications. Open source software development provides many advantages to users of modeling applications, not the least of which is that the software is free and completely extendable. In this review we categorize, enumerate, and describe available open source software packages for molecular modeling and computational chemistry. An updated online version of this catalog can be found at https://opensourcemolecularmodeling.github.io.

  1. Molecular diagnosis of genodermatoses.

    PubMed

    Wessagowit, Vesarat

    2013-01-01

    The progress of molecular genetics helps clinicians to prove or exclude a suspected diagnosis for a vast and yet increasing number of genodermatoses. This leads to precise genetic counselling, prenatal diagnosis and preimplantation genetic haplotyping for many inherited skin conditions. It is also helpful in such occasions as phenocopy, late onset and incomplete penetrance, uniparental disomy, mitochondrial inheritance and pigmentary mosaicism. Molecular methods of two genodermatoses are explained in detail, i.e. genodermatoses with skin fragility and neurofibromatosis type 1.

  2. Molecularly Imprinted Ionomers

    DTIC Science & Technology

    2002-04-05

    ion selective electrodes and ion selective optical sensors using a modified version of the molecular imprinting technique. The modification is a...materials may be the means to realize this goal. An additional application of metal ion imprinted polymers is as sensors . The ability to detect a...been shown to have dramatic effects on polymer properties. The benefits of ionic crosslinking on molecular imprinting are two-fold. First, ionic

  3. Molecular Electronic Shift Registers

    NASA Technical Reports Server (NTRS)

    Beratan, David N.; Onuchic, Jose N.

    1990-01-01

    Molecular-scale shift registers eventually constructed as parts of high-density integrated memory circuits. In principle, variety of organic molecules makes possible large number of different configurations and modes of operation for such shift-register devices. Several classes of devices and implementations in some specific types of molecules proposed. All based on transfer of electrons or holes along chains of repeating molecular units.

  4. Molecular biology in physiology

    SciTech Connect

    Chien, S.; Gargus, J.J.

    1987-08-01

    The aim of this symposium on molecular biology in physiology was to introduce molecular biology to physiologists who had relatively little exposure to the new developments in this field, so that they can become conversant on this topic and contribute to the advancement of physiology by incorporating molecular biological approaches as a part of their research arsenal. This report is a review of the symposium, which consisted of two four-part sessions. Each session had four papers. After the discussion of the basic concepts, terminology, and methodology used in molecular biology, it was shown how these basic principles have been applied to the study of the genes encoding two membrane proteins that have important transport functions (band 3 and ATPase). The second half of the symposium consisted of papers on the state-of-the-art developments in the application of molecular biology to the studies of the atrial natriuretic factor and renin genes, adenylate cyclase-coupled adrenergic receptors, acetylcholine receptors and sodium channel, and long-term and short-term memories. The ultimate goal is that these examples will provide an impetus for the opening of new frontiers of research in physiology by taking advantage of the tools developed from recent advances in molecular biology.

  5. PREFACE: Molecular nanomachines

    NASA Astrophysics Data System (ADS)

    Comtet, Geneviève; Dujardin, Gérald

    2006-08-01

    The concept of molecular nanomachines has become a reality in the past few years in organic and supramolecular chemistry, in biochemistry and in atom-scale manipulation with the scanning tunnelling microscope (STM). In chemistry, molecules can be designed and synthesized to have specific electrical, mechanical, optical or reactive properties. In biochemistry, single natural biomolecules can be isolated and activated as nanomachines. In atom-scale manipulation, the STM can be used to power and to control the operation of individual molecules as molecular nanomachines. The fields of chemical synthesis, biomolecular machines and atom-scale manipulations, have each developed as a separate entity. However, mutual integration of these different research fields appears to be a very fruitful approach for the future of molecular nanomachines. This special section of Journal of Physics: Condensed Matter is the follow-up to a meeting held in Les Houches (France) on 17-21 January 2005 on molecular nanomachines. The section aims to contribute to the readers’ understanding by giving a clear overview of the principal issues of molecular nanomachines. We hope that it will facilitate new collaborations between researchers from these different fields, so necessary for the integrated development of molecular nanomachines.

  6. Molecular classification of gliomas.

    PubMed

    Masui, Kenta; Mischel, Paul S; Reifenberger, Guido

    2016-01-01

    The identification of distinct genetic and epigenetic profiles in different types of gliomas has revealed novel diagnostic, prognostic, and predictive molecular biomarkers for refinement of glioma classification and improved prediction of therapy response and outcome. Therefore, the new (2016) World Health Organization (WHO) classification of tumors of the central nervous system breaks with the traditional principle of diagnosis based on histologic criteria only and incorporates molecular markers. This will involve a multilayered approach combining histologic features and molecular information in an "integrated diagnosis". We review the current state of diagnostic molecular markers for gliomas, focusing on isocitrate dehydrogenase 1 or 2 (IDH1/IDH2) gene mutation, α-thalassemia/mental retardation syndrome X-linked (ATRX) gene mutation, 1p/19q co-deletion and telomerase reverse transcriptase (TERT) promoter mutation in adult tumors, as well as v-raf murine sarcoma viral oncogene homolog B1 (BRAF) and H3 histone family 3A (H3F3A) aberrations in pediatric gliomas. We also outline prognostic and predictive molecular markers, including O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation, and discuss the potential clinical relevance of biologic glioblastoma subtypes defined by integration of multiomics data. Commonly used methods for individual marker detection as well as novel large-scale DNA methylation profiling and next-generation sequencing approaches are discussed. Finally, we illustrate how advances in molecular diagnostics affect novel strategies of targeted therapy, thereby raising new challenges and identifying new leads for personalized treatment of glioma patients.

  7. Workshop on Molecular Evolution

    NASA Technical Reports Server (NTRS)

    Cummings, Michael P.

    2004-01-01

    Molecular evolution has become the nexus of many areas of biological research. It both brings together and enriches such areas as biochemistry, molecular biology, microbiology, population genetics, systematics, developmental biology, genomics, bioinformatics, in vitro evolution, and molecular ecology. The Workshop provides an important contribution to these fields in that it promotes interdisciplinary research and interaction, and thus provides a glue that sticks together disparate fields. Due to the wide range of fields addressed by the study of molecular evolution, it is difficult to offer a comprehensive course in a university setting. It is rare for a single institution to maintain expertise in all necessary areas. In contrast, the Workshop is uniquely able to provide necessary breadth and depth by utilizing a large number of faculty with appropriate expertise. Furthermore, the flexible nature of the Workshop allows for rapid adaptation to changes in the dynamic field of molecular evolution. For example, the 2003 Workshop included recently emergent research areas of molecular evolution of development and genomics.

  8. Interstellar molecular clouds

    NASA Astrophysics Data System (ADS)

    Bally, J.

    1986-04-01

    The physical properties of the molecular phase of the interstellar medium are studied with regard to star formation and the structure of the Galaxy. Most observations of molecular clouds are made with single-dish, high-surface precision radio telescopes, with the best resolution attainable at 0.2 to 1 arcmin; the smallest structures that can be resolved are of order 10 to the 17th cm in diameter. It is now believed that: (1) most of the mass of the Galaxy is in the form of giant molecular clouds; (2) the largest clouds and those responsible for most massive star formation are concentrated in spiral arms; (3) the molecular clouds are the sites of perpetual star formation, and are significant in the chemical evolution of the Galaxy; (4) giant molecular clouds determine the evolution of the kinematic properties of galactic disk stars; (5) the total gas content is diminishing with time; and (6) most clouds have supersonic internal motions and do not form stars on a free-fall time scale. It is concluded that though progress has been made, more advanced instruments are needed to inspect the processes operating within stellar nurseries and to study the distribution of the molecular clouds in more distant galaxies. Instruments presently under construction which are designed to meet these ends are presented.

  9. Molecular toxicity of nanomaterials.

    PubMed

    Chang, Xue-Ling; Yang, Sheng-Tao; Xing, Gengmei

    2014-10-01

    With the rapid developments in the fields of nanoscience and nanotechnlogy, more and more nanomaterials and their based consumer products have been used into our daily life. The safety concerns of nanomaterials have been well recognized by the scientific community and the public. Molecular mechanism of interactions between nanomaterials and biosystems is the most essential topic and final core of the biosafety. In the last two decades, nanotoxicology developed very fast and toxicity phenomena of nanomaterials have been reported. To achieve better understanding and detoxication of nanomaterials, thorough studies of nanotoxicity at molecular level are important. The interactions between nanomaterials and biomolecules have been widely investigated as the first step toward the molecular nanotoxicology. The consequences of such interactions have been discussed in the literature. Besides this, the chemical mechanism of nanotoxicology is gaining more attention, which would lead to a better design of nontoxic nanomaterials. In this review, we focus on the molecular nanotoxicology and explore the toxicity of nanomaterials at molecular level. The molecular level studies of nanotoxicology are summarized and the published nanotoxicological data are revisited.

  10. Nanotechnology Review: Molecular Electronics to Molecular Motors

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash (Technical Monitor)

    1998-01-01

    Reviewing the status of current approaches and future projections, as already published in scientific journals and books, the talk will summarize the direction in which computational and experimental nanotechnologies are progressing. Examples of nanotechnological approaches to the concepts of design and simulation of carbon nanotube based molecular electronic and mechanical devices will be presented. The concepts of nanotube based gears and motors will be discussed. The above is a non-technical review talk which covers long term precompetitive basic research in already published material that has been presented before many US scientific meeting audiences.

  11. Phylogenetic molecular function annotation

    NASA Astrophysics Data System (ADS)

    Engelhardt, Barbara E.; Jordan, Michael I.; Repo, Susanna T.; Brenner, Steven E.

    2009-07-01

    It is now easier to discover thousands of protein sequences in a new microbial genome than it is to biochemically characterize the specific activity of a single protein of unknown function. The molecular functions of protein sequences have typically been predicted using homology-based computational methods, which rely on the principle that homologous proteins share a similar function. However, some protein families include groups of proteins with different molecular functions. A phylogenetic approach for predicting molecular function (sometimes called "phylogenomics") is an effective means to predict protein molecular function. These methods incorporate functional evidence from all members of a family that have functional characterizations using the evolutionary history of the protein family to make robust predictions for the uncharacterized proteins. However, they are often difficult to apply on a genome-wide scale because of the time-consuming step of reconstructing the phylogenies of each protein to be annotated. Our automated approach for function annotation using phylogeny, the SIFTER (Statistical Inference of Function Through Evolutionary Relationships) methodology, uses a statistical graphical model to compute the probabilities of molecular functions for unannotated proteins. Our benchmark tests showed that SIFTER provides accurate functional predictions on various protein families, outperforming other available methods.

  12. Phylogenetic molecular function annotation

    PubMed Central

    Engelhardt, Barbara E; Jordan, Michael I; Repo, Susanna T; Brenner, Steven E

    2010-01-01

    It is now easier to discover thousands of protein sequences in a new microbial genome than it is to biochemically characterize the specific activity of a single protein of unknown function. The molecular functions of protein sequences have typically been predicted using homology-based computational methods, which rely on the principle that homologous proteins share a similar function. However, some protein families include groups of proteins with different molecular functions. A phylogenetic approach for predicting molecular function (sometimes called “phylogenomics”) is an effective means to predict protein molecular function. These methods incorporate functional evidence from all members of a family that have functional characterizations using the evolutionary history of the protein family to make robust predictions for the uncharacterized proteins. However, they are often difficult to apply on a genome-wide scale because of the time-consuming step of reconstructing the phylogenies of each protein to be annotated. Our automated approach for function annotation using phylogeny, the SIFTER (Statistical Inference of Function Through Evolutionary Relationships) methodology, uses a statistical graphical model to compute the probabilities of molecular functions for unannotated proteins. Our benchmark tests showed that SIFTER provides accurate functional predictions on various protein families, outperforming other available methods. PMID:20664722

  13. Mal del pinto in Mexico*

    PubMed Central

    Marquez, Francisco; Rein, Charles R.; Arias, Oswaldo

    1955-01-01

    This report deals with the geographical distribution, prevalence, epidemiology, etiology, serological, clinical, and histopathological features, and treatment of mal del pinto, or pinta, in Mexico. Repository penicillin preparations (PAM and Panbiotic) have been found highly effective in the treatment of this endemic, non-venereal treponematosis. ImagesFIG. 1FIG. 2FIG. 3FIG. 4FIG. 5FIG. 6FIG. 7FIG. 8 PMID:13260889

  14. DNA based molecular motors

    NASA Astrophysics Data System (ADS)

    Michaelis, Jens; Muschielok, Adam; Andrecka, Joanna; Kügel, Wolfgang; Moffitt, Jeffrey R.

    2009-12-01

    Most of the essential cellular processes such as polymerisation reactions, gene expression and regulation are governed by mechanical processes. Controlled mechanical investigations of these processes are therefore required in order to take our understanding of molecular biology to the next level. Single-molecule manipulation and force spectroscopy have over the last 15 years been developed into extremely powerful techniques. Applying these techniques to the investigation of proteins and DNA molecules has led to a mechanistic understanding of protein function on the level of single molecules. As examples for DNA based molecular machines we will describe single-molecule experiments on RNA polymerases as well as on the packaging of DNA into a viral capsid-a process that is driven by one of the most powerful molecular motors.

  15. Molecular modeling of peptides.

    PubMed

    Kuczera, Krzysztof

    2015-01-01

    This article presents a review of the field of molecular modeling of peptides. The main focus is on atomistic modeling with molecular mechanics potentials. The description of peptide conformations and solvation through potentials is discussed. Several important computer simulation methods are briefly introduced, including molecular dynamics, accelerated sampling approaches such as replica-exchange and metadynamics, free energy simulations and kinetic network models like Milestoning. Examples of recent applications for predictions of structure, kinetics, and interactions of peptides with complex environments are described. The reliability of current simulation methods is analyzed by comparison of computational predictions obtained using different models with each other and with experimental data. A brief discussion of coarse-grained modeling and future directions is also presented.

  16. Molecular neuropathology of gliomas.

    PubMed

    Riemenschneider, Markus J; Reifenberger, Guido

    2009-01-01

    Gliomas are the most common primary human brain tumors. They comprise a heterogeneous group of benign and malignant neoplasms that are histologically classified according to the World Health Organization (WHO) classification of tumors of the nervous system. Over the past 20 years the cytogenetic and molecular genetic alterations associated with glioma formation and progression have been intensely studied and genetic profiles as additional aids to the definition of brain tumors have been incorporated in the WHO classification. In fact, first steps have been undertaken in supplementing classical histopathological diagnosis by the use of molecular tests, such as MGMT promoter hypermethylation in glioblastomas or detection of losses of chromosome arms 1p and 19q in oligodendroglial tumors. The tremendous progress that has been made in the use of array-based profiling techniques will likely contribute to a further molecular refinement of glioma classification and lead to the identification of glioma core pathways that can be specifically targeted by more individualized glioma therapies.

  17. [Molecular diagnosis of ADPKD].

    PubMed

    Scolari, Francesco; Savoldi, Gianfranco; Mazza, Cinzia; Izzi, Claudia

    2016-01-01

    Most patients with ADPKD do not need molecular genetic testing. When indicated, Sanger sequencing is the most commonly used technique. When a pathogenic mutation is not identified by Sanger, multiplex ligation-dependent probe amplification analysis (MLPA) should be performed to detect gene rearrangement (insertion or deletion). The next generation sequencing (NGS) techniques can provide high-throughput and comprehensive diagnostic screening at lower cost. Finally, in the future, targeted (TS) or whole exome sequencing (WES) will likely play a role in the molecular diagnostics of ADPKD. Molecular genetic testing is indicated in several conditions: no family history; equivocal/atypical renal imaging; marked discordant disease within family; early and severe PKD; reproductive counseling and pre-implantation genetic diagnosis; related living donor transplantation.

  18. Molecular vibrational energy flow

    NASA Astrophysics Data System (ADS)

    Gruebele, M.; Bigwood, R.

    This article reviews some recent work in molecular vibrational energy flow (IVR), with emphasis on our own computational and experimental studies. We consider the problem in various representations, and use these to develop a family of simple models which combine specific molecular properties (e.g. size, vibrational frequencies) with statistical properties of the potential energy surface and wavefunctions. This marriage of molecular detail and statistical simplification captures trends of IVR mechanisms and survival probabilities beyond the abilities of purely statistical models or the computational limitations of full ab initio approaches. Of particular interest is IVR in the intermediate time regime, where heavy-atom skeletal modes take over the IVR process from hydrogenic motions even upon X H bond excitation. Experiments and calculations on prototype heavy-atom systems show that intermediate time IVR differs in many aspects from the early stages of hydrogenic mode IVR. As a result, IVR can be coherently frozen, with potential applications to selective chemistry.

  19. Stueckelberg and Molecular Physics

    NASA Astrophysics Data System (ADS)

    Lacki, Jan

    The first period of E. C. G. Stueckelberg's scientific career was marked by important contributions he made to molecular physics.1 After publishing his thesis in 1927 in Basel [1] Stueckelberg joined the prestigious Palmer Physical Laboratory in Princeton where he worked under the guidance of Karl Taylor Compton, brother of Arthur Holly Compton. Stueckelberg owed this position devoted several papers to problems of molecular physics. Stueckelberg had the benefit at Princeton of exchanges with other gifted members of the Palmer Physical Laboratory, Philip M. Morse and E. U. Condon among others.3 to a recommendation by A. Sommerfeld.2 In this stimulating environment, he devoted several papers to problems of molecular physics. Stueckelberg had the benefit at Princeton of exchanges with other gifted members of the Palmer Physical Laboratory, Philip M. Morse and E. U. Condon among others.3

  20. Applications of Molecular Imaging

    PubMed Central

    Galbán, Craig; Galbán, Stefanie; Van Dort, Marcian; Luker, Gary D.; Bhojani, Mahaveer S.; Rehemtualla, Alnawaz; Ross, Brian D.

    2015-01-01

    Today molecular imaging technologies play a central role in clinical oncology. The use of imaging techniques in early cancer detection, treatment response and new therapy development is steadily growing and has already significantly impacted clinical management of cancer. In this chapter we will overview three different molecular imaging technologies used for the understanding of disease biomarkers, drug development, or monitoring therapeutic outcome. They are (1) optical imaging (bioluminescence and fluorescence imaging) (2) magnetic resonance imaging (MRI), and (3) nuclear imaging (e.g, single photon emission computed tomography (SPECT) and positron emission tomography (PET)). We will review the use of molecular reporters of biological processes (e.g. apoptosis and protein kinase activity) for high throughput drug screening and new cancer therapies, diffusion MRI as a biomarker for early treatment response and PET and SPECT radioligands in oncology. PMID:21075334

  1. La salud en personas con discapacidad intelectual en España: estudio europeo POMONA-II

    PubMed Central

    Martínez-Leal, Rafael; Salvador-Carulla, Luis; Gutiérrez-Colosía, Mencía Ruiz; Nadal, Margarida; Novell-Alsina, Ramón; Martorell, Almudena; González-Gordón, Rodrigo G.; Mérida-Gutiérrez, M. Reyes; Ángel, Silvia; Milagrosa-Tejonero, Luisa; Rodríguez, Alicia; García-Gutiérrez, Juan C.; Pérez-Vicente, Amado; García-Ibáñez, José; Aguilera-Inés, Francisco

    2011-01-01

    Introducción Estudios internacionales demuestran que existe un patrón diferenciado de salud y una disparidad en la atención sanitaria entre personas con discapacidad intelectual (DI) y población general. Objetivo Obtener datos sobre el estado de salud de las personas con DI y compararlos con datos de población general. Pacientes y métodos Se utilizó el conjunto de indicadores de salud P15 en una muestra de 111 sujetos con DI. Los datos de salud encontrados se compararon según el tipo de residencia de los sujetos y se utilizó la Encuesta Nacional de Salud 2006 para comparar estos datos con los de la población general. Resultados La muestra con DI presentó 25 veces más casos de epilepsia y el doble de obesidad. Un 20% presentó dolor bucal, y existió una alta presencia de problemas sensoriales, de movilidad y psicosis. Sin embargo, encontramos una baja presencia de patologías como la diabetes, la hipertensión, la osteoartritis y la osteoporosis. También presentaron una menor participación en programas de prevención y promoción de la salud, un mayor número de ingresos hospitalarios y un uso menor de los servicios de urgencia. Conclusiones El patrón de salud de las personas con DI difiere del de la población general, y éstas realizan un uso distinto de los servicios sanitarios. Es importante el desarrollo de programas de promoción de salud y de formación profesional específicamente diseñados para la atención de personas con DI, así como la implementación de encuestas de salud que incluyan datos sobre esta población. PMID:21948011

  2. Development and Utilization of InDel Markers to Identify Peanut (Arachis hypogaea) Disease Resistance

    PubMed Central

    Liu, Lifeng; Dang, Phat M.; Chen, Charles Y.

    2015-01-01

    Peanut diseases, such as leaf spot and spotted wilt caused by Tomato Spotted Wilt Virus, can significantly reduce yield and quality. Application of marker assisted plant breeding requires the development and validation of different types of DNA molecular markers. Nearly 10,000 SSR-based molecular markers have been identified by various research groups around the world, but less than 14.5% showed polymorphism in peanut and only 6.4% have been mapped. Low levels of polymorphism limit the application of marker assisted selection (MAS) in peanut breeding programs. Insertion/deletion (InDel) markers have been reported to be more polymorphic than SSRs in some crops. The goals of this study were to identify novel InDel markers and to evaluate the potential use in peanut breeding. Forty-eight InDel markers were developed from conserved sequences of functional genes and tested in a diverse panel of 118 accessions covering six botanical types of cultivated peanut, of which 104 were from the U.S. mini-core. Results showed that 16 InDel markers were polymorphic with polymorphic information content (PIC) among InDels ranged from 0.017 to 0.660. With respect to botanical types, PICs varied from 0.176 for fastigiata var., 0.181 for hypogaea var., 0.306 for vulgaris var., 0.534 for aequatoriana var., 0.556 for peruviana var., to 0.660 for hirsuta var., implying that aequatoriana var., peruviana var., and hirsuta var. have higher genetic diversity than the other types and provide a basis for gene functional studies. Single marker analysis was conducted to associate specific marker to disease resistant traits. Five InDels from functional genes were identified to be significantly correlated to tomato spotted wilt virus (TSWV) infection and leaf spot, and these novel markers will be utilized to identify disease resistant genotype in breeding populations. PMID:26617627

  3. Substructured multibody molecular dynamics.

    SciTech Connect

    Grest, Gary Stephen; Stevens, Mark Jackson; Plimpton, Steven James; Woolf, Thomas B. (Johns Hopkins University, Baltimore, MD); Lehoucq, Richard B.; Crozier, Paul Stewart; Ismail, Ahmed E.; Mukherjee, Rudranarayan M. (Rensselaer Polytechnic Institute, Troy, NY); Draganescu, Andrei I.

    2006-11-01

    We have enhanced our parallel molecular dynamics (MD) simulation software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator, lammps.sandia.gov) to include many new features for accelerated simulation including articulated rigid body dynamics via coupling to the Rensselaer Polytechnic Institute code POEMS (Parallelizable Open-source Efficient Multibody Software). We use new features of the LAMMPS software package to investigate rhodopsin photoisomerization, and water model surface tension and capillary waves at the vapor-liquid interface. Finally, we motivate the recipes of MD for practitioners and researchers in numerical analysis and computational mechanics.

  4. Molecular Rotors as Switches

    PubMed Central

    Xue, Mei; Wang, Kang L.

    2012-01-01

    The use of a functional molecular unit acting as a state variable provides an attractive alternative for the next generations of nanoscale electronics. It may help overcome the limits of conventional MOSFETd due to their potential scalability, low-cost, low variability, and highly integratable characteristics as well as the capability to exploit bottom-up self-assembly processes. This bottom-up construction and the operation of nanoscale machines/devices, in which the molecular motion can be controlled to perform functions, have been studied for their functionalities. Being triggered by external stimuli such as light, electricity or chemical reagents, these devices have shown various functions including those of diodes, rectifiers, memories, resonant tunnel junctions and single settable molecular switches that can be electronically configured for logic gates. Molecule-specific electronic switching has also been reported for several of these device structures, including nanopores containing oligo(phenylene ethynylene) monolayers, and planar junctions incorporating rotaxane and catenane monolayers for the construction and operation of complex molecular machines. A specific electrically driven surface mounted molecular rotor is described in detail in this review. The rotor is comprised of a monolayer of redox-active ligated copper compounds sandwiched between a gold electrode and a highly-doped P+ Si. This electrically driven sandwich-type monolayer molecular rotor device showed an on/off ratio of approximately 104, a read window of about 2.5 V, and a retention time of greater than 104 s. The rotation speed of this type of molecular rotor has been reported to be in the picosecond timescale, which provides a potential of high switching speed applications. Current-voltage spectroscopy (I-V) revealed a temperature-dependent negative differential resistance (NDR) associated with the device. The analysis of the device I–V characteristics suggests the source of the

  5. Visualizing molecular unidirectional rotation

    NASA Astrophysics Data System (ADS)

    Lin, Kang; Song, Qiying; Gong, Xiaochun; Ji, Qinying; Pan, Haifeng; Ding, Jingxin; Zeng, Heping; Wu, Jian

    2015-07-01

    We directly visualize the spatiotemporal evolution of a unidirectional rotating molecular rotational wave packet. Excited by two time-delayed polarization-skewed ultrashort laser pulses, the cigar- or disk-shaped rotational wave packet is impulsively kicked to unidirectionally rotate as a quantum rotor which afterwards disperses and exhibits field-free revivals. The rich dynamics can be coherently controlled by varying the timing or polarization of the excitation laser pulses. The numerical simulations very well reproduce the experimental observations and intuitively revivify the thoroughgoing evolution of the molecular rotational wave packet of unidirectional spin.

  6. Molecular environmental geochemistry

    NASA Astrophysics Data System (ADS)

    O'Day, Peggy A.

    1999-05-01

    The chemistry, mobility, and bioavailability of contaminant species in the natural environment are controlled by reactions that occur in and among solid, aqueous, and gas phases. These reactions are varied and complex, involving changes in chemical form and mass transfer among inorganic, organic, and biochemical species. The field of molecular environmental geochemistry seeks to apply spectroscopic and microscopic probes to the mechanistic understanding of environmentally relevant chemical processes, particularly those involving contaminants and Earth materials. In general, empirical geochemical models have been shown to lack uniqueness and adequate predictive capability, even in relatively simple systems. Molecular geochemical tools, when coupled with macroscopic measurements, can provide the level of chemical detail required for the credible extrapolation of contaminant reactivity and bioavailability over ranges of temperature, pressure, and composition. This review focuses on recent advances in the understanding of molecular chemistry and reaction mechanisms at mineral surfaces and mineral-fluid interfaces spurred by the application of new spectroscopies and microscopies. These methods, such as synchrotron X-ray absorption and scattering techniques, vibrational and resonance spectroscopies, and scanning probe microscopies, provide direct chemical information that can elucidate molecular mechanisms, including element speciation, ligand coordination and oxidation state, structural arrangement and crystallinity on different scales, and physical morphology and topography of surfaces. Nonvacuum techniques that allow examination of reactions in situ (i.e., with water or fluids present) and in real time provide direct links between molecular structure and reactivity and measurements of kinetic rates or thermodynamic properties. Applications of these diverse probes to laboratory model systems have provided fundamental insight into inorganic and organic reactions at

  7. Molecular tectonics: from simple tectons to complex molecular networks.

    PubMed

    Hosseini, Mir Wais

    2005-04-01

    Molecular networks in the crystalline phase are infinite periodic molecular assemblies formed under self-assembly conditions between self-complementary or complementary tectons. These millimeter-size structures may be regarded as hypermolecules formed by supramolecular synthesis using reversible intertecton interactions. Molecular tectonics, based on molecular recognition events and their iteration, is the approach dealing with design and preparation of molecular networks in the solid state. In this Account, an overview of the rational behind this approach is presented. A variety of molecular networks based on van der Waals interactions and hydrogen and coordination bonding possessing diverse connectivity and topology are discussed.

  8. Photoionization of molecular clusters

    NASA Astrophysics Data System (ADS)

    Andres, R. P.; Calo, J. M.

    1981-12-01

    An experimental apparatus consisting of a novel multiple expansion cluster source coupled with a molecular beam system and photoionization mass spectrometer has been designed and constructed. This apparatus has been thoroughly tested and preliminary measurements of the growth kinetics of water clusters and the photoionization cross section of the water dimer have been carried out.

  9. Reading the Molecular Clock.

    ERIC Educational Resources Information Center

    McKean, Kevin

    1983-01-01

    Suggesting that the evolutionary record may be written in proteins and genes, discusses research in which species are compared by immunology, DNA, and radioimmunoassay. Molecular studies show that DNA from humans and chimps is 98 percent identical, a degree of similarity usually occurring only among animals of the same genus. (JN)

  10. Molecular Adsorber Coating

    NASA Technical Reports Server (NTRS)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  11. Polypeptides Based Molecular Electronics

    DTIC Science & Technology

    2008-10-06

    can be nanoengineer/ nanoassemble individual building blocks at the molecular level, atom by atom, to form conducting channel towards realization of...properties of the self-assembled interconnects are characterized as well. These peptides can be nanoengineer/ nanoassemble individual building blocks at

  12. Clickable molecularly imprinted nanoparticles.

    PubMed

    Xu, Changgang; Ye, Lei

    2011-06-07

    Terminal alkynyl and azide groups are introduced on the surface of molecularly imprinted core-shell nanoparticles using precipitation polymerization. These clickable groups enable simple nanoparticle conjugation and surface modification under mild reaction conditions, opening new opportunities for nanoparticle-based assays and chemical sensing.

  13. The molecular universe

    NASA Astrophysics Data System (ADS)

    Tielens, A. G. G. M.

    2013-07-01

    Molecular absorption and emission bands dominate the visible, infrared, and submillimeter spectra of most objects with associated gas. These observations reveal a surprisingly rich array of molecular species and attest to a complex chemistry taking place in the harsh environment of the interstellar medium of galaxies. Molecules are truly everywhere and an important component of interstellar gas. This review surveys molecular observations in the various spectral windows and summarizes the chemical and physical processes involved in the formation and evolution of interstellar molecules. The rich organic inventory of space reflects the multitude of chemical processes involved that, on the one hand, build up molecules an atom at a time and, on the other hand, break down large molecules injected by stars to smaller fragments. Both this bottom-up and the trickle-down chemistry are reviewed. The emphasis is on understanding the characteristics of complex polycyclic aromatic hydrocarbon molecules and fullerenes and their role in chemistry as well as the intricate interaction of gas-phase ion-molecule and neutral-neutral reactions and the chemistry taking place on grain surfaces in dense clouds in setting the organic inventory of regions of star and planet formation and their implications for the chemical history of the Solar System. Many aspects of molecular astrophysics are illustrated with recent observations of the HIFI instrument on the Herschel Space Observatory.

  14. Molecular Models in Biology

    ERIC Educational Resources Information Center

    Goodman, Richard E.

    1970-01-01

    Describes types of molecular models (ball-and-stick, framework, and space-filling) and evaluates commercially available kits. Gives instructions for constructive models from polystyrene balls and pipe-cleaners. Models are useful for class demonstrations although not sufficiently accurate for research use. Illustrations show biologically important…

  15. Making Molecular Borromean Rings

    ERIC Educational Resources Information Center

    Pentecost, Cari D.; Tangchaivang, Nichol; Cantrill, Stuart J.; Chichak, Kelly S.; Peters, Andrea J.; Stoddart, Fraser J.

    2007-01-01

    A procedure that requires seven 4-hour blocks of time to allow undergraduate students to prepare the molecular Borromean rings (BRs) on a gram-scale in 90% yield is described. The experiment would serve as a nice capstone project to culminate any comprehensive organic laboratory course and expose students to fundamental concepts, symmetry point…

  16. Molecular contributions to conservation

    USGS Publications Warehouse

    Haig, Susan M.

    1998-01-01

    Recent advances in molecular technology have opened a new chapter in species conservation efforts, as well as population biology. DNA sequencing, MHC (major histocompatibility complex), minisatellite, microsatellite, and RAPD (random amplified polymorphic DNA) procedures allow for identification of parentage, more distant relatives, founders to new populations, unidentified individuals, population structure, effective population size, population-specific markers, etc. PCR (polymerase chain reaction) amplification of mitochondrial DNA, nuclear DNA, ribosomal DNA, chloroplast DNA, and other systems provide for more sophisticated analyses of metapopulation structure, hybridization events, and delineation of species, subspecies, and races, all of which aid in setting species recovery priorities. Each technique can be powerful in its own right but is most credible when used in conjunction with other molecular techniques and, most importantly, with ecological and demographic data collected from the field. Surprisingly few taxa of concern have been assayed with any molecular technique. Thus, rather than showcasing exhaustive details from a few well-known examples, this paper attempts to present a broad range of cases in which molecular techniques have been used to provide insight into conservation efforts.

  17. Molecular ion photofragment spectroscopy

    SciTech Connect

    Bustamente, S.W.

    1983-11-01

    A new molecular ion photofragment spectrometer is described which features a supersonic molecular beam ion source and a radio frequency octapole ion trap interaction region. This unique combination allows several techniques to be applied to the problem of detecting a photon absorption event of a molecular ion. In particular, it may be possible to obtain low resolution survey spectra of exotic molecular ions by using a direct vibrational predissociation process, or by using other more indirect detection methods. The use of the spectrometer is demonstrated by measuring the lifetime of the O/sub 2//sup +/(/sup 4/..pi../sub u/) metastable state which is found to consist of two main components: the /sup 4/..pi../sub 5/2/ and /sup 4/..pi../sub -1/2/ spin components having a long lifetime (approx. 129 ms) and the /sup 4/..pi../sub 3/2/ and /sup 4/..pi../sub 1/2/ spin components having a short lifetime (approx. 6 ms).

  18. Molecular fMRI

    PubMed Central

    Bartelle, Benjamin B.; Barandov, Ali

    2016-01-01

    Comprehensive analysis of brain function depends on understanding the dynamics of diverse neural signaling processes over large tissue volumes in intact animals and humans. Most existing approaches to measuring brain signaling suffer from limited tissue penetration, poor resolution, or lack of specificity for well-defined neural events. Here we discuss a new brain activity mapping method that overcomes some of these problems by combining MRI with contrast agents sensitive to neural signaling. The goal of this “molecular fMRI” approach is to permit noninvasive whole-brain neuroimaging with specificity and resolution approaching current optical neuroimaging methods. In this article, we describe the context and need for molecular fMRI as well as the state of the technology today. We explain how major types of MRI probes work and how they can be sensitized to neurobiological processes, such as neurotransmitter release, calcium signaling, and gene expression changes. We comment both on past work in the field and on challenges and promising avenues for future development. SIGNIFICANCE STATEMENT Brain researchers currently have a choice between measuring neural activity using cellular-level recording techniques, such as electrophysiology and optical imaging, or whole-brain imaging methods, such as fMRI. Cellular level methods are precise but only address a small portion of mammalian brains; on the other hand, whole-brain neuroimaging techniques provide very little specificity for neural pathways or signaling components of interest. The molecular fMRI techniques we discuss have particular potential to combine the specificity of cellular-level measurements with the noninvasive whole-brain coverage of fMRI. On the other hand, molecular fMRI is only just getting off the ground. This article aims to offer a snapshot of the status and future prospects for development of molecular fMRI techniques. PMID:27076413

  19. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Marina Del Rey, CA. 80.1118... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del...

  20. La utilizacion de los mapas conceptuales en la ensenanza de biologia y su efecto sobre el dominio del proceso de fotosintesis en los estudiantes universitarios

    NASA Astrophysics Data System (ADS)

    Gonzalez Rivera, Maria M.

    Se investigo el efecto de los mapas conceptuales sobre el dominio del proceso de fotosintesis en estudiantes universitarios. La investigacion utilizo dos estrategias: mapas conceptuales individuales y mapas conceptuales colaborativos, con el fin de investigar si existen diferencias significativas en el dominio del proceso de fotosintesis. El analisis de los datos incluyo aspectos cualitativos y cuantitativos. Se desprende del estudio que el 80% de los estudiantes describen la utilizacion de los mapas conceptuales como una experiencia beneficiosa. El 70% de los estudiantes expreso que los mapas conceptuales son utiles en el aprendizaje del proceso de fotosintesis y el 61% indico que facilitan la comprension de los conceptos. Los hallazgos mas importantes del analisis cuantitativo indican que los estudiantes que utilizaron los mapas conceptuales mejoraron significativamente su desempeno en la posprueba global. Se utilizo la prueba Mann-Whitney para investigar si existian diferencias significativas en la posprueba y preprueba global, el valor de W = 1945.0, para un valor p de 0.00, lo cual establece diferencias significativas. Para determinar si existian diferencias significativas entre la posprueba y preprueba del grupo individual, se realizo la prueba nuevamente. El valor de W correspondio a 490.5, que es significativo, con un valor p de 0.00. Se concluye que existen diferencias significativas entre la ejecucion de la posprueba y preprueba del grupo individual. Los datos proveen suficiente evidencia para sostener que los estudiantes que utilizaron la estrategia de mapas conceptuales individuales mejoraron el dominio del proceso de fotosintesis significativamente. Se realizo nuevamente la prueba para los resultados de posprueba y preprueba del grupo colaborativo. El valor de W correspondio a 446 con un valor p de 0.00. Se concluyo que existen diferencias significativas entre la ejecucion de la posprueba y preprueba del grupo colaborativo. Finalmente, se efectuo una

  1. [Molecular abnormalities in lymphomas].

    PubMed

    Delsol, G

    2010-11-01

    Numerous molecular abnormalities have been described in lymphomas. They are of diagnostic and prognostic value and are taken into account for the WHO classification of these tumors. They also shed some light on the underlying molecular mechanisms involved in lymphomas. Overall, four types of molecular abnormalities are involved: mutations, translocations, amplifications and deletions of tumor suppressor genes. Several techniques are available to detect these molecular anomalies: conventional cytogenetic analysis, multicolor FISH, CGH array or gene expression profiling using DNA microarrays. In some lymphomas, genetic abnormalities are responsible for the expression of an abnormal protein (e.g. tyrosine-kinase, transcription factor) detectable by immunohistochemistry. In the present review, molecular abnormalities observed in the most frequent B, T or NK cell lymphomas are discussed. In the broad spectrum of diffuse large B-cell lymphomas microarray analysis shows mostly two subgroups of tumors, one with gene expression signature corresponding to germinal center B-cell-like (GCB: CD10+, BCL6 [B-Cell Lymphoma 6]+, centerine+, MUM1-) and a subgroup expressing an activated B-cell-like signature (ABC: CD10-, BCL6-, centerine-, MUM1+). Among other B-cell lymphomas with well characterized molecular abnormalies are follicular lymphoma (BCL2 deregulation), MALT lymphoma (Mucosa Associated Lymphoid Tissue) [API2-MALT1 (mucosa-associated-lymphoid-tissue-lymphoma-translocation-gene1) fusion protein or deregulation BCL10, MALT1, FOXP1. MALT1 transcription factors], mantle cell lymphoma (cycline D1 [CCND1] overexpression) and Burkitt lymphoma (c-Myc expression). Except for ALK (anaplastic lymphoma kinase)-positive anaplastic large cell lymphoma, well characterized molecular anomalies are rare in lymphomas developed from T or NK cells. Peripheral T cell lymphomas not otherwise specified are a heterogeneous group of tumors with frequent but not recurrent molecular abnormalities

  2. Some Stereochemical Principles from Polymers: Molecular Symmetry and Molecular Flexibility

    ERIC Educational Resources Information Center

    Price, Charles C.

    1973-01-01

    Discusses the use of the properties of polyethylene, polypropylene, polyisobutylene, and their three epoxides to illustrate the relationships of entropy to molecular properties and the concepts of molecular chirality, geometry, and flexibility. (CC)

  3. FORT Molecular Ecology Laboratory

    USGS Publications Warehouse

    Oyler-McCance, Sara J.; Stevens, P.D.

    2011-01-01

    The mission of the U.S. Geological Survey (USGS) at the Fort Collins Science Center Molecular Ecology Laboratory is to use the tools and concepts of molecular genetics to address a variety of complex management questions and conservation issues facing the management of the Nation's fish and wildlife resources. Together with our partners, we design and implement studies to document genetic diversity and the distribution of genetic variation among individuals, populations, and species. Information from these studies is used to support wildlife-management planning and conservation actions. Current and past studies have provided information to assess taxonomic boundaries, inform listing decisions made under the Endangered Species Act, identify unique or genetically depauperate populations, estimate population size or survival rates, develop management or recovery plans, breed wildlife in captivity, relocate wildlife from one location to another, and assess the effects of environmental change.

  4. Molecular psychiatry of zebrafish

    PubMed Central

    Stewart, Adam Michael; Ullmann, Jeremy F.P.; Norton, William H.J.; Brennan, Caroline H.; Parker, Matthew O.; Gerlai, Robert; Kalueff, Allan V.

    2014-01-01

    Due to their well-characterized neural development and high genetic homology to mammals, zebrafish (Danio rerio) have emerged as a powerful model organism in the field of biological psychiatry. Here, we discuss the molecular psychiatry of zebrafish, and its implications for translational neuroscience research and modeling CNS disorders. In particular, we outline recent genetic and technological developments allowing for in-vivo examinations, high-throughput screening and whole-brain analyses in larval and adult zebrafish. We also summarize the application of these molecular techniques to the understanding of neuropsychiatric disease, outlining the potential of zebrafish for modeling complex brain disorders, including attention-deficit/hyperactivity disorder (ADHD), aggression, post-traumatic stress and substance abuse. Critically evaluating the advantages and limitations of larval and adult fish tests, we suggest that zebrafish models become a rapidly emerging new field in modern biological psychiatry research. PMID:25349164

  5. Molecular processes in comets

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1988-01-01

    The transition dipole moments of the c 3 Pi u - a 3 Sigma g +, i 3 Pi g - c 3 Pi u, and i 3 Pi g - b 3 Sigma u + transitions of molecular hydrogen were calculated over a wide range of internuclear distances R. Calculations of the emission spectra are nearing completion. Substantial progress was made in the calculation of the absorption coefficient of a colliding pair of hydrogen atoms in the binary encounter approximation. Detailed calculations were performed on the continuum emission arising from the excitation of the a 3 sigma g + state of H2 by the impact of electrons of various energies. Each curve is labelled by the electron energy in electron volts. The strong emission near Lyman alpha is interesting in that it is produced by excitation of molecular hydrogen.

  6. An Artificial Molecular Transporter

    PubMed Central

    Schäfer, Christian; Ragazzon, Giulio; Colasson, Benoit; La Rosa, Marcello; Silvi, Serena

    2015-01-01

    Abstract The transport of substrates is one of the main tasks of biomolecular machines in living organisms. We report a synthetic small‐molecule system designed to catch, displace, and release molecular cargo in solution under external control. The system consists of a bistable rotaxane that behaves as an acid–base controlled molecular shuttle, whose ring component bears a tether ending with a nitrile group. The latter can be coordinated to a ruthenium complex that acts as the load, and dissociated upon irradiation with visible light. The cargo loading/unloading and ring transfer/return processes are reversible and can be controlled independently. The robust coordination bond ensures that the cargo remains attached to the device while the transport takes place. PMID:27308223

  7. Interactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Schroeder, Daniel V.

    2015-03-01

    Physics students now have access to interactive molecular dynamics simulations that can model and animate the motions of hundreds of particles, such as noble gas atoms, that attract each other weakly at short distances but repel strongly when pressed together. Using these simulations, students can develop an understanding of forces and motions at the molecular scale, nonideal fluids, phases of matter, thermal equilibrium, nonequilibrium states, the Boltzmann distribution, the arrow of time, and much more. This article summarizes the basic features and capabilities of such a simulation, presents a variety of student exercises using it at the introductory and intermediate levels, and describes some enhancements that can further extend its uses. A working simulation code, in html5 and javascript for running within any modern Web browser, is provided as an online supplement.

  8. Templated quasicrystalline molecular layers

    NASA Astrophysics Data System (ADS)

    Smerdon, Joe; Young, Kirsty; Lowe, Michael; Hars, Sanger; Yadav, Thakur; Hesp, David; Dhanak, Vinod; Tsai, An-Pang; Sharma, Hem Raj; McGrath, Ronan

    2014-03-01

    Quasicrystals are materials with long range ordering but no periodicity. We report scanning tunneling microscopy (STM) observations of quasicrystalline molecular layers on five-fold quasicrystal surfaces. The molecules adopt positions and orientations on the surface consistent with the quasicrystalline ordering of the substrate. Carbon-60 adsorbs atop sufficiently-separated Fe atoms on icosahedral Al-Cu-Fe to form a unique quasicrystalline lattice whereas further C60 molecules decorate remaining surface Fe atoms in a quasi-degenerate fashion. Pentacene (Pn) adsorbs at tenfold-symmetric points around surface-bisected rhombic triacontahedral clusters in icosahedral Ag-In-Yb. These systems constitute the first demonstrations of quasicrystalline molecular ordering on a template. EPSRC EP/D05253X/1, EP/D071828/1, UK BIS.

  9. Molecular biology of potyviruses.

    PubMed

    Revers, Frédéric; García, Juan Antonio

    2015-01-01

    Potyvirus is the largest genus of plant viruses causing significant losses in a wide range of crops. Potyviruses are aphid transmitted in a nonpersistent manner and some of them are also seed transmitted. As important pathogens, potyviruses are much more studied than other plant viruses belonging to other genera and their study covers many aspects of plant virology, such as functional characterization of viral proteins, molecular interaction with hosts and vectors, structure, taxonomy, evolution, epidemiology, and diagnosis. Biotechnological applications of potyviruses are also being explored. During this last decade, substantial advances have been made in the understanding of the molecular biology of these viruses and the functions of their various proteins. After a general presentation on the family Potyviridae and the potyviral proteins, we present an update of the knowledge on potyvirus multiplication, movement, and transmission and on potyvirus/plant compatible interactions including pathogenicity and symptom determinants. We end the review providing information on biotechnological applications of potyviruses.

  10. Molecular diagnosis of onychomycosis.

    PubMed

    Petinataud, D; Berger, S; Contet-Audonneau, N; Machouart, M

    2014-12-01

    Onychomycosis is a frequent cause of nail infections due to dermatophytes. Molds and yeast may also be responsible of these pathologies. Antifungal treatments are frequently given without a mycological diagnosis, partly because of the requisite time for obtaining the biological results. The mycological diagnosis requires a direct microscopic examination and a culture in order to accurately identify the fungal genus and species. Nevertheless, this conventional diagnosis is often time consuming due to the delay of fungal cultures and presents disadvantages that make it not sufficient enough to give a precise and confident response to the clinicians. Therefore additional tests have been developed to help distinguish onychomycosis from other nail disorders. Among them, molecular biology techniques offer modern and rapid tools to improve traditional microbiological diagnosis. In this review, we first present the conventional diagnosis methods for onychomycosis and then we describe the main molecular biology tools and the currently available commercial kits that allow a rapid detection of the pathology.

  11. Primer on molecular genetics

    SciTech Connect

    Not Available

    1992-04-01

    This report is taken from the April 1992 draft of the DOE Human Genome 1991--1992 Program Report, which is expected to be published in May 1992. The primer is intended to be an introduction to basic principles of molecular genetics pertaining to the genome project. The material contained herein is not final and may be incomplete. Techniques of genetic mapping and DNA sequencing are described.

  12. Molecular-beam scattering

    SciTech Connect

    Vernon, M.F.

    1983-07-01

    The molecular-beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces. Chapter 1 reports results of a low-energy (0.2 kcal/mole) elastic-scattering study of the He-Ar pair potential. The purpose of the study was to accurately characterize the shape of the potential in the well region, by scattering slow He atoms produced by expanding a mixture of He in N/sub 2/ from a cooled nozzle. Chapter 2 contains measurements of the vibrational predissociation spectra and product translational energy for clusters of water, benzene, and ammonia. The experiments show that most of the product energy remains in the internal molecular motions. Chapter 3 presents measurements of the reaction Na + HCl ..-->.. NaCl + H at collision energies of 5.38 and 19.4 kcal/mole. This is the first study to resolve both scattering angle and velocity for the reaction of a short lived (16 nsec) electronic excited state. Descriptions are given of computer programs written to analyze molecular-beam expansions to extract information characterizing their velocity distributions, and to calculate accurate laboratory elastic-scattering differential cross sections accounting for the finite apparatus resolution. Experimental results which attempted to determine the efficiency of optically pumping the Li(2/sup 2/P/sub 3/2/) and Na(3/sup 2/P/sub 3/2/) excited states are given. A simple three-level model for predicting the steady-state fraction of atoms in the excited state is included.

  13. Molecular Vaccines for Malaria

    DTIC Science & Technology

    2010-01-01

    is a p:micularly elegant example of molecular design applied to a recombi nant prote in , combining rational antigen choice (the vaccine uses a major...ing list of examples concordant with these principles. One is rhe ex istence of cryptic epitopes- normally immunologically silent epitopes rhar when...to divert· the immune response from cryptic epitopes formed by the potential binding site lying within the groove,l7 AMAI illustrates the barrier

  14. Atomic and molecular theory

    SciTech Connect

    Inokuti, Mitio.

    1990-01-01

    The multifaceted role of theoretical physics in understanding the earliest stages of radiation action is discussed. Scientific topics chosen for the present discourse include photoabsorption, electron collisions, and ionic collisions, and electron transport theory, Connections of atomic and molecular physics with condensed-matter physics are also discussed. The present article includes some historical perspective and an outlook for the future. 114 refs., 3 figs.

  15. Molecular Biology of Archaebacteria

    DTIC Science & Technology

    1988-03-31

    elucidate at the molecular level some of the features that make archaebacteria unique and distinguish them from eubacteria and eucaryotes. Three types...regulate translation of the mRNA by a mechanism similar to that employed in eubacteria . Thus halophilic archaebacteria retain the same gene order and...possibly also the same regulatory mechanism for controlling ribosomal protein synthesis that is found in eubacteria . Ribosomal protein structure: The

  16. [Hereditary deafness: molecular genetics].

    PubMed

    Hardelin, Jean-Pierre; Denoyelle, Françoise; Levilliers, Jacqueline; Simmler, Marie-Christine; Petit, Christine

    2004-03-01

    This article outlines recent advances in explaining hereditary deafness in molecular terms, focusing on isolated (i.e. nonsyndromic) hearing loss. The number of genes identified (36 to date) is growing rapidly. However, difficulties inherent in genetic linkage analysis, coupled with the possible involvement of environmental causes, have so far prevented the characterization of the main genes causative or predisposing to the late-onset forms of deafness.

  17. Molecular opacities for exoplanets

    PubMed Central

    Bernath, Peter F.

    2014-01-01

    Spectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanets are reviewed based on existing measurements and model predictions for hot Jupiters and super-Earths. Molecular opacities needed to simulate astronomical observations can be obtained from laboratory measurements, ab initio calculations or a combination of the two approaches. This discussion article focuses mainly on laboratory measurements of hot molecules as needed for exoplanet spectroscopy. PMID:24664921

  18. Linear artificial molecular muscles.

    PubMed

    Liu, Yi; Flood, Amar H; Bonvallet, Paul A; Vignon, Scott A; Northrop, Brian H; Tseng, Hsian-Rong; Jeppesen, Jan O; Huang, Tony J; Brough, Branden; Baller, Marko; Magonov, Sergei; Solares, Santiago D; Goddard, William A; Ho, Chih-Ming; Stoddart, J Fraser

    2005-07-13

    Two switchable, palindromically constituted bistable [3]rotaxanes have been designed and synthesized with a pair of mechanically mobile rings encircling a single dumbbell. These designs are reminiscent of a "molecular muscle" for the purposes of amplifying and harnessing molecular mechanical motions. The location of the two cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings can be controlled to be on either tetrathiafulvalene (TTF) or naphthalene (NP) stations, either chemically ((1)H NMR spectroscopy) or electrochemically (cyclic voltammetry), such that switching of inter-ring distances from 4.2 to 1.4 nm mimics the contraction and extension of skeletal muscle, albeit on a shorter length scale. Fast scan-rate cyclic voltammetry at low temperatures reveals stepwise oxidations and movements of one-half of the [3]rotaxane and then of the other, a process that appears to be concerted at room temperature. The active form of the bistable [3]rotaxane bears disulfide tethers attached covalently to both of the CBPQT(4+) ring components for the purpose of its self-assembly onto a gold surface. An array of flexible microcantilever beams, each coated on one side with a monolayer of 6 billion of the active bistable [3]rotaxane molecules, undergoes controllable and reversible bending up and down when it is exposed to the synchronous addition of aqueous chemical oxidants and reductants. The beam bending is correlated with flexing of the surface-bound molecular muscles, whereas a monolayer of the dumbbell alone is inactive under the same conditions. This observation supports the hypothesis that the cumulative nanoscale movements within surface-bound "molecular muscles" can be harnessed to perform larger-scale mechanical work.

  19. Handbook of molecular lasers

    NASA Astrophysics Data System (ADS)

    Cheo, Peter K.

    The technology and applications of molecular lasers (MLs) are examined in chapters contributed by leading experts. Topics addressed include ML emission spectra, CO2 TEA lasers, RF-discharge-excited CO2 lasers, high-energy short-pulse CO2 lasers, high-power electron-beam-controlled CO2 lasers, HF/DF chemical lasers, optically pumped FIR MLs, and transients and instabilities in FIR MLs. Extensive diagrams, drawings, graphs, photographs, and tables of numerical data are provided.

  20. Communication: Molecular gears.

    PubMed

    Burnell, E Elliott; de Lange, Cornelis A; Meerts, W Leo

    2016-09-07

    The (1)H nuclear magnetic resonance spectrum of hexamethylbenzene orientationally ordered in the nematic liquid crystal ZLI-1132 is analysed using covariance matrix adaptation evolution strategy. The spectrum contains over 350 000 lines with many overlapping transitions, from which four independent direct dipolar couplings are obtained. The rotations of the six methyl groups appear to be correlated due to mutual steric hindrance. Adjacent methyl groups show counter-rotating or geared motion. Hexamethylbenzene thus behaves as a molecular hexagonal gear.

  1. Molecular opacities for exoplanets.

    PubMed

    Bernath, Peter F

    2014-04-28

    Spectroscopic observations of exoplanets are now possible by transit methods and direct emission. Spectroscopic requirements for exoplanets are reviewed based on existing measurements and model predictions for hot Jupiters and super-Earths. Molecular opacities needed to simulate astronomical observations can be obtained from laboratory measurements, ab initio calculations or a combination of the two approaches. This discussion article focuses mainly on laboratory measurements of hot molecules as needed for exoplanet spectroscopy.

  2. Functional Molecular Ecological Networks

    PubMed Central

    Zhou, Jizhong; Deng, Ye; Luo, Feng; He, Zhili; Tu, Qichao; Zhi, Xiaoyang

    2010-01-01

    Biodiversity and its responses to environmental changes are central issues in ecology and for society. Almost all microbial biodiversity research focuses on “species” richness and abundance but not on their interactions. Although a network approach is powerful in describing ecological interactions among species, defining the network structure in a microbial community is a great challenge. Also, although the stimulating effects of elevated CO2 (eCO2) on plant growth and primary productivity are well established, its influences on belowground microbial communities, especially microbial interactions, are poorly understood. Here, a random matrix theory (RMT)-based conceptual framework for identifying functional molecular ecological networks was developed with the high-throughput functional gene array hybridization data of soil microbial communities in a long-term grassland FACE (free air, CO2 enrichment) experiment. Our results indicate that RMT is powerful in identifying functional molecular ecological networks in microbial communities. Both functional molecular ecological networks under eCO2 and ambient CO2 (aCO2) possessed the general characteristics of complex systems such as scale free, small world, modular, and hierarchical. However, the topological structures of the functional molecular ecological networks are distinctly different between eCO2 and aCO2, at the levels of the entire communities, individual functional gene categories/groups, and functional genes/sequences, suggesting that eCO2 dramatically altered the network interactions among different microbial functional genes/populations. Such a shift in network structure is also significantly correlated with soil geochemical variables. In short, elucidating network interactions in microbial communities and their responses to environmental changes is fundamentally important for research in microbial ecology, systems microbiology, and global change. PMID:20941329

  3. Molecularly Imprinted Biodegradable Nanoparticles

    PubMed Central

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization. PMID:28071745

  4. Molecular basis of alcoholism.

    PubMed

    Most, Dana; Ferguson, Laura; Harris, R Adron

    2014-01-01

    Acute alcohol intoxication causes cellular changes in the brain that last for hours, while chronic alcohol use induces widespread neuroadaptations in the nervous system that can last a lifetime. Chronic alcohol use and the progression into dependence involve the remodeling of synapses caused by changes in gene expression produced by alcohol. The progression of alcohol use, abuse, and dependence can be divided into stages, which include intoxication, withdrawal, and craving. Each stage is associated with specific changes in gene expression, cellular function, brain circuits, and ultimately behavior. What are the molecular mechanisms underlying the transition from recreational use (acute) to dependence (chronic)? What cellular adaptations result in drug memory retention, leading to the persistence of addictive behaviors, even after prolonged drug abstinence? Research into the neurobiology of alcoholism aims to answer these questions. This chapter will describe the molecular adaptations caused by alcohol use and dependence, and will outline key neurochemical participants in alcoholism at the molecular level, which are also potential targets for therapy.

  5. Thermoelectricity in molecular junctions.

    PubMed

    Reddy, Pramod; Jang, Sung-Yeon; Segalman, Rachel A; Majumdar, Arun

    2007-03-16

    By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 +/- 2.1 microvolts per kelvin (muV/K), +12.9 +/- 2.2 muV/K, and +14.2 +/- 3.2 muV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction in these heterojunctions, whereas the Au Fermi level position for Au-BDT-Au junctions was identified to be 1.2 eV above the highest occupied molecular orbital level of BDT. The ability to study thermoelectricity in molecular junctions provides the opportunity to address these fundamental unanswered questions about their electronic structure and to begin exploring molecular thermoelectric energy conversion.

  6. Molecularly Imprinted Biodegradable Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  7. Molecularly Imprinted Biodegradable Nanoparticles.

    PubMed

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-10

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  8. Fluorinated benzalkylsilane molecular rectifiers

    PubMed Central

    Lamport, Zachary A.; Broadnax, Angela D.; Harrison, David; Barth, Katrina J.; Mendenhall, Lee; Hamilton, Clayton T.; Guthold, Martin; Thonhauser, Timo; Welker, Mark E.; Jurchescu, Oana D.

    2016-01-01

    We report on the synthesis and electrical properties of nine new alkylated silane self-assembled monolayers (SAMs) – (EtO)3Si(CH2)nN = CHPhX where n = 3 or 11 and X = 4-CF3, 3,5-CF3, 3-F-4-CF3, 4-F, or 2,3,4,5,6-F, and explore their rectification behavior in relation to their molecular structure. The electrical properties of the films were examined in a metal/insulator/metal configuration, with a highly-doped silicon bottom contact and a eutectic gallium-indium liquid metal (EGaIn) top contact. The junctions exhibit high yields (>90%), a remarkable resistance to bias stress, and current rectification ratios (R) between 20 and 200 depending on the structure, degree of order, and internal dipole of each molecule. We found that the rectification ratio correlates positively with the strength of the molecular dipole moment and it is reduced with increasing molecular length. PMID:27897250

  9. Molecular biology of hearing

    PubMed Central

    Stöver, Timo; Diensthuber, Marc

    2012-01-01

    The inner ear is our most sensitive sensory organ and can be subdivided into three functional units: organ of Corti, stria vascularis and spiral ganglion. The appropriate stimulus for the organ of hearing is sound, which travels through the external auditory canal to the middle ear where it is transmitted to the inner ear. The inner ear houses the hair cells, the sensory cells of hearing. The inner hair cells are capable of mechanotransduction, the transformation of mechanical force into an electrical signal, which is the basic principle of hearing. The stria vascularis generates the endocochlear potential and maintains the ionic homeostasis of the endolymph. The dendrites of the spiral ganglion form synaptic contacts with the hair cells. The spiral ganglion is composed of neurons that transmit the electrical signals from the cochlea to the central nervous system. In recent years there has been significant progress in research on the molecular basis of hearing. An increasing number of genes and proteins related to hearing are being identified and characterized. The growing knowledge of these genes contributes not only to greater appreciation of the mechanism of hearing but also to a deeper understanding of the molecular basis of hereditary hearing loss. This basic research is a prerequisite for the development of molecular diagnostics and novel therapies for hearing loss. PMID:22558056

  10. Molecular Classification of Medulloblastoma

    PubMed Central

    KIJIMA, Noriyuki; KANEMURA, Yonehiro

    2016-01-01

    Medulloblastoma (MB) is one of the most frequent malignant brain tumors in children. The current standard treatment regimen consists of surgical resection, craniospinal irradiation, and adjuvant chemotherapy. Although these treatments have the potential to increase the survival of 70–80% of patients with MB, they are also associated with serious treatment-induced morbidity. The current risk stratification of MB is based on clinical factors, including age at presentation, metastatic status, and the presence of residual tumor following resection. In addition, recent genomic studies indicate that MB consists of at least four distinct molecular subgroups: WNT, sonic hedgehog (SHH), Group 3, and Group 4. WNT and SHH MBs are characterized by aberrations in the WNT and SHH signaling pathways, respectively. WNT MB has the best prognosis compared to the other MBs, while SHH MB has an intermediate prognosis. The underlying signaling pathways associated with Group 3 and 4 MBs have not been identified. Group 3 MB is frequently associated with metastasis, resulting in a poor prognosis, while Group 4 is sometimes associated with metastasis and has an intermediate prognosis. Group 4 is the most frequent MB and represents 35% of all MBs. These findings suggest that MB is a heterogeneous disease, and that MB subgroups have distinct molecular, demographic, and clinical characteristics. The molecular classification of MBs is redefining the risk stratification of patients with MB, and has the potential to identify new therapeutic strategies for the treatment of MB. PMID:27238212

  11. Fluorinated benzalkylsilane molecular rectifiers

    NASA Astrophysics Data System (ADS)

    Lamport, Zachary A.; Broadnax, Angela D.; Harrison, David; Barth, Katrina J.; Mendenhall, Lee; Hamilton, Clayton T.; Guthold, Martin; Thonhauser, Timo; Welker, Mark E.; Jurchescu, Oana D.

    2016-11-01

    We report on the synthesis and electrical properties of nine new alkylated silane self-assembled monolayers (SAMs) – (EtO)3Si(CH2)nN = CHPhX where n = 3 or 11 and X = 4-CF3, 3,5-CF3, 3-F-4-CF3, 4-F, or 2,3,4,5,6-F, and explore their rectification behavior in relation to their molecular structure. The electrical properties of the films were examined in a metal/insulator/metal configuration, with a highly-doped silicon bottom contact and a eutectic gallium-indium liquid metal (EGaIn) top contact. The junctions exhibit high yields (>90%), a remarkable resistance to bias stress, and current rectification ratios (R) between 20 and 200 depending on the structure, degree of order, and internal dipole of each molecule. We found that the rectification ratio correlates positively with the strength of the molecular dipole moment and it is reduced with increasing molecular length.

  12. An InDel-based linkage map of hot pepper (Capsicum annuum).

    PubMed

    Li, Weipeng; Cheng, Jiaowen; Wu, Zhiming; Qin, Cheng; Tan, Shu; Tang, Xin; Cui, Junjie; Zhang, Li; Hu, Kailin

    Two independent pepper (Capsicum annuum) genomes were published recently, opening a new era of molecular genetics research on pepper. However, pepper molecular marker technologies are still mainly focusing on the simple sequence repeats derived from public database or genomic library. The development and application of the third generation marker system such as single nucleotide polymorphisms, structure variations as well as insertion/deletion polymorphisms (InDels) is still in its infancy. In the present study, we developed InDel markers for pepper genetic mapping with the convenience of two whole-genome re-sequenced inbred lines BA3 (C. annuum) and B702 (C. annuum). A total of 154,519 and 149,755 InDel (1-5 bp) sites were identified for BA3 and B702, respectively, by the alignment of re-sequencing reads to Zunla-1 reference genome. Then, 14,498 InDel sites (only 4 and 5 bp) that are different between BA3 and B702 were predicted. Finally, within a random set of 1,000 primer pairs, 251 InDel markers were validated and mapped onto a linkage map using F2 population derived from the intraspecific cross BA3 × B702. The first InDel-based map, named as BB-InDel map, consisted of 12 linkage groups, covered a genetic distance of 1,178.01 cM and the average distance between bin markers was 5.01 cM. Compared to the Zunla-1 reference physical map, high consistency was observed on all 12 chromosomes, and the total length of scaffold anchored and physical distance covered by this map was 299.66 and 2,558.68 Mb, respectively, which accounted for 8.95 and 76.38 % of the Zunla-1 reference genome (3.35 Gb), respectively. Furthermore, 37 scaffolds (total length of 36.21 Mb) from the pseudo-chromosome (P0) of the current genome assembly were newly assigned to the corresponding chromosomes by 40 InDel markers. Thus, this map provided good genome coverage and would be useful for basic and applied research in pepper.

  13. Calidad del aire interior en las escuelas

    EPA Pesticide Factsheets

    EPA ha desarrollado el Programa de Herramientas de Calidad del Aire Interior para las Escuelas para reducir la exposición a los contaminantes ambientales en las mismas a través de la adopción voluntaria de las prácticas para manejar la calidad del aire int

  14. Molecular and clinical study of 61 Angelman syndrome patients

    SciTech Connect

    Saitoh, Shinji; Harada, Naoki; Jinno, Yoshihiro; Niikawa, Norio; Imaizumi, Kiyoshi; Kuroki, Yoshikazu; Fukushima; Yoshimitsu; Sugimoto, Tateo; Renedo, Monica

    1994-08-15

    We analyzed 61 Angelman syndrome (AS) patients by cytogenetic and molecular techniques. On the basis of molecular findings, the patients were classified into the following 4 groups: familial cases without deletion, familial cases with submicroscopic deletion, sporadic cases with deletion, and sporadic cases without deletion. Among 53 sporadic cases, 37 (70%) had molecular deletion, which commonly extended from D15S9 to D15S12, although not all deletions were identical. Of 8 familial cases, 3 sibs from one family had a molecular deletion involving only 2 loci, D15S10 and GABRB3, which define the critical region for AS phenotypes. The parental origin of deletion, both in sporadic and familial cases, was exclusively maternal and consistent with a genomic imprinting hypothesis. Among sporadic and familial cases without deletion, no uniparental disomy was found and most of them were shown to inherit chromosomes 15 from both parents (biparental inheritance). A discrepancy between cytogenetic and molecular deletion was observed in 14 (26%) of 53 patients in whom cytogenetic analysis could be performed. Ten (43%) of 23 patients with a normal karyotype showed a molecular deletion, and 4 (13%) of 30 patients with cytogenetic deletion, del(15) (q11q13), showed no molecular deletion. Most clinical manifestations, including neurological signs and facial characteristics, were not distinct in each group except for hypopigmentation of skin or hair. Familial cases with submicroscopic deletion were not associated with hypopigmentation. These findings suggested that a gene for hypopigmentation is located outside the critical region of AS and is not imprinted. 37 refs., 2 figs., 4 tabs.

  15. Catalysts for Change: Three Case Studies of Quality Education Worldwide = Catalizadores del Cambio: Tres Casos de Estudio sobre la Educacion de Calidad en el Mundo

    ERIC Educational Resources Information Center

    Puriefoy, Wendy D.

    2007-01-01

    Public education is the cornerstone of democracy and is absolutely fundamental to a democratic, civil and prosperous society. Beyond the boundaries of the United States, other countries are working to provide quality education to their children through civil society institutions. In particular, there are three extraordinary organizations in Peru,…

  16. Experiencias de Vida de la Mujer Adulta: Estudio de Caso de Lideres en Desarrollo del Programa de Administracion y Supervision Educativa

    ERIC Educational Resources Information Center

    Morales-Roman, Gildrette M.

    2012-01-01

    Since the twentieth century to present, the role of women in society has undergone fundamental changes. Women, today, has assumed many different task and new roles, becoming part of professional workforce and increasing level of education by aspiring a higher education gaining access to leadership positions. The purpose of this qualitative…

  17. La Aplicacion de las Bases de Datos al Estudio Historico del Espanol (The Application of Databases to the Historical Study of Spanish).

    ERIC Educational Resources Information Center

    Nadal, Gloria Claveria; Lancis, Carlos Sanchez

    1997-01-01

    Notes that the employment of databases to the study of the history of a language is a method that allows for substantial improvement in investigative quality. Illustrates this with the example of the application of this method to two studies of the history of Spanish developed in the Language and Information Seminary of the Independent University…

  18. An economic prefeasibility study of geothermal energy development at Platanares, Honduras. Estudio economico de prefactibilidad del desarrollo de energia geotermica en Platanares, Honduras

    SciTech Connect

    Trocki, L.K.

    1989-09-01

    The expected economic benefits from development of a geothermal power plant at Platanares in the Department of Copan, Honduras are evaluated in this report. The economic benefits of geothermal plants ranging in size from a 10-MW plant in the shallow reservoir to a 20-, 30-, 55-, or 110-MW plant in the assumed deeper reservoir were measured by computing optimal expansion plans for each size of geothermal plant. Savings are computed as the difference in present value cost between a plan that contains no geothermal plant and one that does. Present value savings in millions of 1987 dollars range from $25 million for the 10-MW plant to $110 million for the 110-MW plant -- savings of 6% to 25% over the time period 1988 through 2008. 8 refs., 9 figs., 6 tabs.

  19. THE CALIFORNIA MOLECULAR CLOUD

    SciTech Connect

    Lada, Charles J.; Lombardi, Marco; Alves, Joao F. E-mail: mlombard@eso.or

    2009-09-20

    We present an analysis of wide-field infrared extinction maps of a region in Perseus just north of the Taurus-Auriga dark cloud complex. From this analysis we have identified a massive, nearby, but previously unrecognized, giant molecular cloud (GMC). Both a uniform foreground star density and measurements of the cloud's velocity field from CO observations indicate that this cloud is likely a coherent structure at a single distance. From comparison of foreground star counts with Galactic models, we derive a distance of 450 +- 23 pc to the cloud. At this distance the cloud extends over roughly 80 pc and has a mass of {approx} 10{sup 5} M{sub sun}, rivaling the Orion (A) molecular cloud as the largest and most massive GMC in the solar neighborhood. Although surprisingly similar in mass and size to the more famous Orion molecular cloud (OMC) the newly recognized cloud displays significantly less star formation activity with more than an order of magnitude fewer young stellar objects than found in the OMC, suggesting that both the level of star formation and perhaps the star formation rate in this cloud are an order of magnitude or more lower than in the OMC. Analysis of extinction maps of both clouds shows that the new cloud contains only 10% the amount of high extinction (A{sub K} > 1.0 mag) material as is found in the OMC. This, in turn, suggests that the level of star formation activity and perhaps the star formation rate in these two clouds may be directly proportional to the total amount of high extinction material and presumably high density gas within them and that there might be a density threshold for star formation on the order of n(H{sub 2}) {approx} a few x 10{sup 4} cm{sup -3}.

  20. Molecular proxies for paleoclimatology

    NASA Astrophysics Data System (ADS)

    Eglinton, Timothy I.; Eglinton, Geoffrey

    2008-10-01

    We summarize the applications of molecular proxies in paleoclimatology. Marine molecular records especially are proving to be of value but certain environmentally persistent compounds can also be measured in lake sediments, loess deposits and ice cores. The fundamentals of this approach are the molecular parameters, the compound abundances and carbon, hydrogen, nitrogen and oxygen isotopic contents which can be derived by the analysis of sediment extracts. These afford proxy measures which can be interpreted in terms of the conditions which control climate and also reflect its operation. We discuss two types of proxy; those of terrigenous and those of aquatic origin, and exemplify their application in the study of marine sediments through the medium of ten case studies based in the Atlantic, Mediterranean and Pacific Oceans, and in Antarctica. The studies are mainly for periods in the present, the Holocene and particularly the last glacial/interglacial, but they also include one study from the Cretaceous. The terrigenous proxies, which are measures of continental vegetation, are based on higher plant leaf wax compounds, i.e. long-chain (circa C 30) hydrocarbons, alcohols and acids. They register the relative contributions of C 3 vs. C 4 type plants to the vegetation in the source areas. The two marine proxies are measures of sea surface temperatures (SST). The longer established one, (U 37K') is based on the relative abundances of C 37 alkenones photosynthesized by unicellular algae, members of the Haptophyta. The newest proxy (TEX 86) is based on C 86 glycerol tetraethers (GDGTs) synthesized in the water column by some of the archaeal microbiota, the Crenarchaeota.

  1. VMD: visual molecular dynamics.

    PubMed

    Humphrey, W; Dalke, A; Schulten, K

    1996-02-01

    VMD is a molecular graphics program designed for the display and analysis of molecular assemblies, in particular biopolymers such as proteins and nucleic acids. VMD can simultaneously display any number of structures using a wide variety of rendering styles and coloring methods. Molecules are displayed as one or more "representations," in which each representation embodies a particular rendering method and coloring scheme for a selected subset of atoms. The atoms displayed in each representation are chosen using an extensive atom selection syntax, which includes Boolean operators and regular expressions. VMD provides a complete graphical user interface for program control, as well as a text interface using the Tcl embeddable parser to allow for complex scripts with variable substitution, control loops, and function calls. Full session logging is supported, which produces a VMD command script for later playback. High-resolution raster images of displayed molecules may be produced by generating input scripts for use by a number of photorealistic image-rendering applications. VMD has also been expressly designed with the ability to animate molecular dynamics (MD) simulation trajectories, imported either from files or from a direct connection to a running MD simulation. VMD is the visualization component of MDScope, a set of tools for interactive problem solving in structural biology, which also includes the parallel MD program NAMD, and the MDCOMM software used to connect the visualization and simulation programs. VMD is written in C++, using an object-oriented design; the program, including source code and extensive documentation, is freely available via anonymous ftp and through the World Wide Web.

  2. Molecular mechanisms of etoposide

    PubMed Central

    Montecucco, Alessandra; Zanetta, Francesca; Biamonti, Giuseppe

    2015-01-01

    Etoposide derives from podophyllotoxin, a toxin found in the American Mayapple. It was first synthesized in 1966 and approved for cancer therapy in 1983 by the U.S. Food and Drug Administration (Hande, 1998[25]). Starting from 1980s several studies demonstrated that etoposide targets DNA topoisomerase II activities thus leading to the production of DNA breaks and eliciting a response that affects several aspects of cell metabolisms. In this review we will focus on molecular mechanisms that account for the biological effect of etoposide. PMID:26600742

  3. Switchable molecular magnets

    PubMed Central

    SATO, Osamu

    2012-01-01

    Various molecular magnetic compounds whose magnetic properties can be controlled by external stimuli have been developed, including electrochemically, photochemically, and chemically tunable bulk magnets as well as a phototunable antiferromagnetic phase of single chain magnet. In addition, we present tunable paramagnetic mononuclear complexes ranging from spin crossover complexes and valence tautomeric complexes to Co complexes in which orbital angular momentum can be switched. Furthermore, we recently developed several switchable clusters and one-dimensional coordination polymers. The switching of magnetic properties can be achieved by modulating metals, ligands, and molecules/ions in the second sphere of the complexes. PMID:22728438

  4. [Molecular physiology of aging].

    PubMed

    Khavinson, V Kh; Morozov, V G; Malinin, V V

    2001-01-01

    The article is dedicated to the analysis of the peptide bioregulators role in molecular mechanisms of ageing and age-related pathology development. There has been put forward the concept of peptide regulation of ageing based on the priority data of authors long-term investigations on inhibition of involution processes in organs and tissues developed with age and restoration of specific proteins synthesis in cells under the influence of natural and synthetic peptide bioregulators. The prospects of peptide bioregulators employment in gerontological practice are being discussed in the paper with the purpose of treatment and prevention of age-associated pathology and human longevity increase.

  5. Switchable molecular magnets.

    PubMed

    Sato, Osamu

    2012-01-01

    Various molecular magnetic compounds whose magnetic properties can be controlled by external stimuli have been developed, including electrochemically, photochemically, and chemically tunable bulk magnets as well as a phototunable antiferromagnetic phase of single chain magnet. In addition, we present tunable paramagnetic mononuclear complexes ranging from spin crossover complexes and valence tautomeric complexes to Co complexes in which orbital angular momentum can be switched. Furthermore, we recently developed several switchable clusters and one-dimensional coordination polymers. The switching of magnetic properties can be achieved by modulating metals, ligands, and molecules/ions in the second sphere of the complexes.

  6. Molecular Toxicology of Chromatin

    DTIC Science & Technology

    1992-01-01

    FINAL 01 Jan 89 TO 31 Dec 91 4. ITL ANO SUS Y, L RE %UMAS MOLECULAR TOXICOLOGY OF CHROMATIN AFOSR-89-0231 PE - 61102F AUT PR - 2312 TA - A5 Dr Ernest Kun...Waterbury, CT), 2-mercaptoethanol, NAD+, NADPH, nucleo- tides, sodium tungstate , hydrogen peroxide, Tris and MES buffers from Sigma (St. Louis, MO...ml) with sodium tungstate (5.93 g, in 20 ml H20) for 1.5 h followed by extraction of the green product into ethyl acetate, washing with 0.1 N HCl, and

  7. Supported Molecular Matrix Electrophoresis.

    PubMed

    Matsuno, Yu-Ki; Kameyama, Akihiko

    2015-01-01

    Mucins are difficult to separate using conventional gel electrophoresis methods such as SDS-PAGE and agarose gel electrophoresis, owing to their large size and heterogeneity. On the other hand, cellulose acetate membrane electrophoresis can separate these molecules, but is not compatible with glycan analysis. Here, we describe a novel membrane electrophoresis technique, termed "supported molecular matrix electrophoresis" (SMME), in which a porous polyvinylidene difluoride (PVDF) membrane filter is used to achieve separation. This description includes the separation, visualization, and glycan analysis of mucins with the SMME technique.

  8. Molecular origin of friction

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Zhang, Tao; Hu, Yuanzhong

    2004-01-01

    The wearless friction originating from molecular interactions has been discussed in this paper. We find that the frictional properties are closely related to the structural match of two surfaces in relative motion. For the surfaces with incommensurate structure and week inter-surface interaction, zero static and kinetic friction can be achieved. In a sliding considered as in a quasi-static state, the energy dissipation initiates when interfacial particles move in a discontinuous fashion, which gives rise to a finite kinetic friction. The state of superlubricity is a result of computer simulations, but the prediction will encourage people to look for a technical approach to realizing the state of super low friction.

  9. [Breast self-examination in users of the Instituto Mexicano del Seguro Social from Teapa, Tabasco, Mexico].

    PubMed

    Córdova-Cadena, Samuel; González-Pozos, Patricia Vanessa; Zavala-González, Marco Antonio

    2015-01-01

    Objetivo: determinar la proporción de mujeres de 40 años o más que se realizan correctamente autoexploración mamaria en la Unidad Médica Familiar 18 del Instituto Mexicano del Seguro Social, en Teapa, Tabasco, México, en el año 2011. Métodos: estudio transversal, de un universo de 1457 mujeres del que se obtuvo una muestra probabilística de 127, seleccionadas sistematizadamente. Se incluyeron variables sociodemográficas, antecedentes heredofamiliares de cáncer de mama y la evaluación de la técnica de autoexploración. La información fue obtenida de expedientes clínicos y listas de cotejo. Se obtuvo estadística descriptiva. Resultados: La edad media fue de 52.7 ± 9.3 con un intervalo de confianza de 40-80 años. La escolaridad predominante fue la primaria con 35.4 %. Hubo antecedente heredofamiliar de tumor maligno de las mamas en 11 %. La madre fue el familiar más frecuente con este antecedente (42.9 %). Hubo una correcta autoexploración mamaria en 0.8 %. Conclusiones: la proporción de mujeres que realizan correctamente la autoexploración mamaria es alarmantemente baja. No se encontraron factores asociados. Se requieren intervenciones educativas para corregir el problema.

  10. Epidemiological surveillance of ovine hydatidosis in Tierra del Fuego, Patagonia Argentina, 1997-1999.

    PubMed

    Zanini, Fabián; Gonzalo, Roberto; Pérez, Héctor; Aparici, Inés; Soto, Ximena; Guerrero, Juvenal; Cerrone, Gloria; Elissondo, Celina

    2006-06-15

    ). This is the first time that a molecular analysis was performed for the E. granulosus isolates from Tierra del Fuego.

  11. MOLECULAR VACUUM PUMP

    DOEpatents

    Eckberg, E.E.

    1960-09-27

    A multiple molecular vacuum pump capable of producing a vacuum of the order of 10/sup -9/ mm Hg is described. The pump comprises a casing of an aggregate of paired and matched cylindrical plates, a recessed portion on one face of each plate concentrically positioned formed by a radially extending wall and matching the similarly recessed portion of its twin plate of that pair of plates and for all paired and matched plates; a plurality of grooves formed in the radially extending walls of each and all recesses progressing in a spiral manner from their respective starting points out at the periphery of the recess inwardly to the central area; a plurality of rotors rotatably mounted to closely occupy the spaces as presented by the paired and matched recesses between all paired plates; a hollowed drive-shaft perforated at points adjacent to the termini of all spiral grooves; inlet ports at the starting points of all grooves and through all plates at common points to each respectively; and a common outlet passage presented by the hollow portion of the perforated hollowed drive-shaft of the molecular pump. (AEC)

  12. The Molecular Atlas Project

    NASA Astrophysics Data System (ADS)

    Silverberg, Jesse; Yin, Peng

    The promise of super-resolution microscopy is a technology to discover new biological mechanisms that occur at smaller length scales then previously observable. However, with higher-resolution, we generally lose the larger spatial context of the image itself. The Molecular Atlas Project (MAP) directly asks how these competing interests between super-resolution imaging and broader spatially contextualized information can be reconciled. MAP enables us to acquire, visualize, explore, and annotate proteomic image data representing 7 orders of magnitude in length ranging from molecular (nm) to tissue (cm) scales. This multi-scale understanding is made possible by combining multiplexed DNA-PAINT, a DNA nanotechnology approach to super-resolution imaging, with ``big-data'' strategies for information management and image visualization. With these innovations combined, MAP enables us to explore cell-specific heterogeneity in ductal carcinoma for every cellin a cm-sized tissue section, analyze organoid growth for advances in high-throughput tissue-on-a-chip technology, and examine individual synapses for connectome mapping over extremely wide areas. Ultimately, MAP is a fundamentally new way to interact with multiscale biophysical data.

  13. Multiscale reactive molecular dynamics

    NASA Astrophysics Data System (ADS)

    Knight, Chris; Lindberg, Gerrick E.; Voth, Gregory A.

    2012-12-01

    Many processes important to chemistry, materials science, and biology cannot be described without considering electronic and nuclear-level dynamics and their coupling to slower, cooperative motions of the system. These inherently multiscale problems require computationally efficient and accurate methods to converge statistical properties. In this paper, a method is presented that uses data directly from condensed phase ab initio simulations to develop reactive molecular dynamics models that do not require predefined empirical functions. Instead, the interactions used in the reactive model are expressed as linear combinations of interpolating functions that are optimized by using a linear least-squares algorithm. One notable benefit of the procedure outlined here is the capability to minimize the number of parameters requiring nonlinear optimization. The method presented can be generally applied to multiscale problems and is demonstrated by generating reactive models for the hydrated excess proton and hydroxide ion based directly on condensed phase ab initio molecular dynamics simulations. The resulting models faithfully reproduce the water-ion structural properties and diffusion constants from the ab initio simulations. Additionally, the free energy profiles for proton transfer, which is sensitive to the structural diffusion of both ions in water, are reproduced. The high fidelity of these models to ab initio simulations will permit accurate modeling of general chemical reactions in condensed phase systems with computational efficiency orders of magnitudes greater than currently possible with ab initio simulation methods, thus facilitating a proper statistical sampling of the coupling to slow, large-scale motions of the system.

  14. Molecular phylogenetics before sequences

    PubMed Central

    Ragan, Mark A; Bernard, Guillaume; Chan, Cheong Xin

    2014-01-01

    From 1971 to 1985, Carl Woese and colleagues generated oligonucleotide catalogs of 16S/18S rRNAs from more than 400 organisms. Using these incomplete and imperfect data, Carl and his colleagues developed unprecedented insights into the structure, function, and evolution of the large RNA components of the translational apparatus. They recognized a third domain of life, revealed the phylogenetic backbone of bacteria (and its limitations), delineated taxa, and explored the tempo and mode of microbial evolution. For these discoveries to have stood the test of time, oligonucleotide catalogs must carry significant phylogenetic signal; they thus bear re-examination in view of the current interest in alignment-free phylogenetics based on k-mers. Here we consider the aims, successes, and limitations of this early phase of molecular phylogenetics. We computationally generate oligonucleotide sets (e-catalogs) from 16S/18S rRNA sequences, calculate pairwise distances between them based on D2 statistics, compute distance trees, and compare their performance against alignment-based and k-mer trees. Although the catalogs themselves were superseded by full-length sequences, this stage in the development of computational molecular biology remains instructive for us today. PMID:24572375

  15. Molecular Epidemiology of Amebiasis

    PubMed Central

    Ali, Ibne Karim M.; Clark, C. Graham; Petri, William A.

    2008-01-01

    Entamoeba histolytica, the causative agent of human amebiasis, remains a significant cause of morbidity and mortality in developing countries and is responsible for up to 100,000 deaths worldwide each year. Entamoeba dispar, morphologically indistinguishable from E. histolytica, is more common in humans in many parts of the world. Similarly Entamoeba moshkovskii, which was long considered to be a free-living ameba, is also morphologically identical to E. histolytica and E. dispar, and is highly prevalent in some E. histolytica endemic countries. However, the only species to cause disease in humans is E. histolytica. Most old epidemiological data on E. histolytica are unusable as the techniques employed do not differentiate between the above three Entamoeba species. Molecular tools are now available not only to diagnose these species accurately but also to study intra-species genetic diversity. Recent studies suggest that only a minority of all E. histolytica infections progress to development of clinical symptoms in the host and there exist population level differences between the E. histolytica strains isolated from the asymptomatic and symptomatic individuals. Nevertheless the underlying factors responsible for variable clinical outcome of infection by E. histolytica remain largely unknown. We anticipate that the recently completed E. histolytica genome sequence and new molecular techniques will rapidly advance our understanding of the epidemiology and pathogenicity of amebiasis. PMID:18571478

  16. Molecular enzymology of lipoxygenases.

    PubMed

    Ivanov, Igor; Heydeck, Dagmar; Hofheinz, Katharina; Roffeis, Jana; O'Donnell, Valerie B; Kuhn, Hartmut; Walther, Matthias

    2010-11-15

    Lipoxygenases (LOXs) are lipid peroxidizing enzymes, implicated in the pathogenesis of inflammatory and hyperproliferative diseases, which represent potential targets for pharmacological intervention. Although soybean LOX1 was discovered more than 60years ago, the structural biology of these enzymes was not studied until the mid 1990s. In 1993 the first crystal structure for a plant LOX was solved and following this protein biochemistry and molecular enzymology became major fields in LOX research. This review focuses on recent developments in molecular enzymology of LOXs and summarizes our current understanding of the structural basis of LOX catalysis. Various hypotheses explaining the reaction specificity of different isoforms are critically reviewed and their pros and cons briefly discussed. Moreover, we summarize the current knowledge of LOX evolution by profiling the existence of LOX-related genomic sequences in the three kingdoms of life. Such sequences are found in eukaryotes and bacteria but not in archaea. Although the biological role of LOXs in lower organisms is far from clear, sequence data suggests that this enzyme family might have evolved shortly after the appearance of atmospheric oxygen on earth.

  17. Towards graphyne molecular electronics.

    PubMed

    Li, Zhihai; Smeu, Manuel; Rives, Arnaud; Maraval, Valérie; Chauvin, Remi; Ratner, Mark A; Borguet, Eric

    2015-02-20

    α-Graphyne, a carbon-expanded version of graphene ('carbo-graphene') that was recently evidenced as an alternative zero-gap semiconductor, remains a theoretical material. Nevertheless, using specific synthesis methods, molecular units of α-graphyne ('carbo-benzene' macrocycles) can be inserted between two anilinyl (4-NH2-C6H4)-anchoring groups that allow these fragments to form molecular junctions between gold electrodes. Here, electrical measurements by the scanning tunnelling microscopy (STM) break junction technique and electron transport calculations are carried out on such a carbo-benzene, providing unprecedented single molecule conductance values: 106 nS through a 1.94-nm N-N distance, essentially 10 times the conductance of a shorter nanographenic hexabenzocoronene analogue. Deleting a C4 edge of the rigid C18 carbo-benzene circuit results in a flexible 'carbo-butadiene' molecule that has a conductance 40 times lower. Furthermore, carbo-benzene junctions exhibit field-effect transistor behaviour when an electrochemical gate potential is applied, opening the way for device applications. All the results are interpreted on the basis of theoretical calculations.

  18. Evolution of molecular clouds

    NASA Technical Reports Server (NTRS)

    Sevenster, M.

    1993-01-01

    The evolution of interstellar molecular hydrogen was studied, with a special interest for the formation and evolution of molecular clouds and star formation within them, by a two-dimensional hydrodynamical simulation performed on a rectangular grid of physical sizes on the order of 100 pc. It is filled with an initial density of approx. 1 cm(exp -3), except for one cell (approx. 1 pc(exp 2)) at the center of the grid where an accretion core of 1-10(exp 3) solar masses is placed. The grid is co-moving with the gridcenter that is on a circular orbit around the Galactic center and that also is the guiding center of epicyclic approximation of orbits of the matter surrounding it. The initial radial velocity is zero; to account for differential rotation the initial tangential velocity (i.e. the movement around the galactic center) is proportional to the radial distance to the grid center. The rate is comparable to the rotation rate at the Local Standard of Rest. The influence of galactic rotation is noticed by spiral or elliptical forms, but on much longer time scales than self gravitation and cooling processes. Density and temperature are kept constant at the boundaries and no inflow is allowed along the tangential boundaries.

  19. Towards graphyne molecular electronics

    NASA Astrophysics Data System (ADS)

    Li, Zhihai; Smeu, Manuel; Rives, Arnaud; Maraval, Valérie; Chauvin, Remi; Ratner, Mark A.; Borguet, Eric

    2015-02-01

    α-Graphyne, a carbon-expanded version of graphene (‘carbo-graphene’) that was recently evidenced as an alternative zero-gap semiconductor, remains a theoretical material. Nevertheless, using specific synthesis methods, molecular units of α-graphyne (‘carbo-benzene’ macrocycles) can be inserted between two anilinyl (4-NH2-C6H4)-anchoring groups that allow these fragments to form molecular junctions between gold electrodes. Here, electrical measurements by the scanning tunnelling microscopy (STM) break junction technique and electron transport calculations are carried out on such a carbo-benzene, providing unprecedented single molecule conductance values: 106 nS through a 1.94-nm N-N distance, essentially 10 times the conductance of a shorter nanographenic hexabenzocoronene analogue. Deleting a C4 edge of the rigid C18 carbo-benzene circuit results in a flexible ‘carbo-butadiene’ molecule that has a conductance 40 times lower. Furthermore, carbo-benzene junctions exhibit field-effect transistor behaviour when an electrochemical gate potential is applied, opening the way for device applications. All the results are interpreted on the basis of theoretical calculations.

  20. Molecular mechanisms in gliomagenesis.

    PubMed

    Hulleman, Esther; Helin, Kristian

    2005-01-01

    Glioma, and in particular high-grade astrocytoma termed glioblastoma multiforme (GBM), is the most common primary tumor of the brain. Primarily because of its diffuse nature, there is no effective treatment for GBM, and relatively little is known about the processes by which it develops. Therefore, in order to design novel therapies and treatments for GBM, research has recently intensified to identify the cellular and molecular mechanisms leading to GBM formation. Modeling of astrocytomas by genetic manipulation of mice suggests that deregulation of the pathways that control gliogenesis during normal brain development, such as the differentiation of neural stem cells (NSCs) into astrocytes, might contribute to GBM formation. These pathways include growth factor-induced signal transduction routes and processes that control cell cycle progression, such as the p16-CDK4-RB and the ARF-MDM2-p53 pathways. The expression of several of the components of these signaling cascades has been found altered in GBM, and recent data indicate that combinations of mutations in these pathways may contribute to GBM formation, although the exact mechanisms are still to be uncovered. Use of novel techniques including large-scale genomics and proteomics in combination with relevant mouse models will most likely provide novel insights into the molecular mechanisms underlying glioma formation and will hopefully lead to development of treatment modalities for GBM.

  1. Molecular control of oogenesis.

    PubMed

    Sánchez, Flor; Smitz, Johan

    2012-12-01

    Oogenesis is a complex process regulated by a vast number of intra- and extra-ovarian factors. Oogonia, which originate from primordial germ cells, proliferate by mitosis and form primary oocytes that arrest at the prophase stage of the first meiotic division until they are fully-grown. Within primary oocytes, synthesis and accumulation of RNAs and proteins throughout oogenesis are essential for oocyte growth and maturation; and moreover, crucial for developing into a viable embryo after fertilization. Oocyte meiotic and developmental competence is gained in a gradual and sequential manner during folliculogenesis and is related to the fact that the oocyte grows in interaction with its companion somatic cells. Communication between oocyte and its surrounding granulosa cells is vital, both for oocyte development and for granulosa cells differentiation. Oocytes depend on differentiated cumulus cells, which provide them with nutrients and regulatory signals needed to promote oocyte nuclear and cytoplasmic maturation and consequently the acquisition of developmental competence.The purpose of this article is to summarize recent knowledge on the molecular aspects of oogenesis and oocyte maturation, and the crucial role of cumulus-cell interactions, highlighting the valuable contribution of experimental evidences obtained in animal models. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

  2. Molecular Comb Development

    SciTech Connect

    Ferrell, T.L.; Thundat, G.T.; Witkowski, C.E., III

    2007-07-17

    This CRADA was developed to enable ORNL to assist Protein Discovery, Inc. to develop a novel biomolecular separation system based on an ORNL patent application 'Photoelectrochemical Molecular Comb' by Thundat, Ferrell, and Brown. The Molecular Comb concept is based on creating light-induced charge carriers at a semiconductor-liquid interface, which is kept at a potential control such that a depletion layer is formed in the semiconductor. Focusing light from a low-power illumination source creates electron-hole pairs, which get separated in the depletion layer. The light-induced charge carriers reaching the surface attract oppositely charged biomolecules present in the solution. The solution is a buffer solution with very small concentrations of biomolecules. As the focused light is moved across the surface of the semiconductor-liquid interface, the accumulated biomolecules follow the light beam. A thin layer of gel or other similar material on the surface of the semiconductor can act as a sieving medium for separating the biomolecules according to their sizes.

  3. Quantum molecular master equations

    NASA Astrophysics Data System (ADS)

    Brechet, Sylvain D.; Reuse, Francois A.; Maschke, Klaus; Ansermet, Jean-Philippe

    2016-10-01

    We present the quantum master equations for midsize molecules in the presence of an external magnetic field. The Hamiltonian describing the dynamics of a molecule accounts for the molecular deformation and orientation properties, as well as for the electronic properties. In order to establish the master equations governing the relaxation of free-standing molecules, we have to split the molecule into two weakly interacting parts, a bath and a bathed system. The adequate choice of these systems depends on the specific physical system under consideration. Here we consider a first system consisting of the molecular deformation and orientation properties and the electronic spin properties and a second system composed of the remaining electronic spatial properties. If the characteristic time scale associated with the second system is small with respect to that of the first, the second may be considered as a bath for the first. Assuming that both systems are weakly coupled and initially weakly correlated, we obtain the corresponding master equations. They describe notably the relaxation of magnetic properties of midsize molecules, where the change of the statistical properties of the electronic orbitals is expected to be slow with respect to the evolution time scale of the bathed system.

  4. Photoinduced diffusion molecular transport

    NASA Astrophysics Data System (ADS)

    Rozenbaum, Viktor M.; Dekhtyar, Marina L.; Lin, Sheng Hsien; Trakhtenberg, Leonid I.

    2016-08-01

    We consider a Brownian photomotor, namely, the directed motion of a nanoparticle in an asymmetric periodic potential under the action of periodic rectangular resonant laser pulses which cause charge redistribution in the particle. Based on the kinetics for the photoinduced electron redistribution between two or three energy levels of the particle, the time dependence of its potential energy is derived and the average directed velocity is calculated in the high-temperature approximation (when the spatial amplitude of potential energy fluctuations is small relative to the thermal energy). The thus developed theory of photoinduced molecular transport appears applicable not only to conventional dichotomous Brownian motors (with only two possible potential profiles) but also to a much wider variety of molecular nanomachines. The distinction between the realistic time dependence of the potential energy and that for a dichotomous process (a step function) is represented in terms of relaxation times (they can differ on the time intervals of the dichotomous process). As shown, a Brownian photomotor has the maximum average directed velocity at (i) large laser pulse intensities (resulting in short relaxation times on laser-on intervals) and (ii) excited state lifetimes long enough to permit efficient photoexcitation but still much shorter than laser-off intervals. A Brownian photomotor with optimized parameters is exemplified by a cylindrically shaped semiconductor nanocluster which moves directly along a polar substrate due to periodically photoinduced dipole moment (caused by the repetitive excited electron transitions to a non-resonant level of the nanocylinder surface impurity).

  5. Molecular defects in Sanfilippo syndrome type B (mucopolysaccharidosis IIIB).

    PubMed

    Beesley, C E; Jackson, M; Young, E P; Vellodi, A; Winchester, B G

    2005-01-01

    Sanfilippo syndrome type B (mucopolysaccharidosis IIIB) is an autosomal recessive disease that is caused by the deficiency of the lysosomal enzyme alpha-N-acetylglucosaminidase (NAGLU). NAGLU is involved in the degradation of the glycosaminoglycan (GAG) heparan sulphate, and a deficiency results in the accumulation of partially degraded GAGs inside lysosomes. Early clinical symptoms include hyperactivity, aggressiveness and delayed development, followed by progressive mental deterioration, although there are a small number of late-onset attenuated cases. The gene for NAGLU has been fully characterized and we report the molecular analysis of 18 Sanfilippo B families. In total, 34 of the 36 mutant alleles were characterized in this study and 20 different mutations were identified including 8 novel changes (R38W, V77G, 407-410del4, 703delT, A246P, Y335C, 1487delT, E639X). The four novel missense mutations were transiently expressed in Chinese hamster ovary cells and all were shown to decrease the NAGLU activity markedly, although A246P did produce 12.7% residual enzyme activity.

  6. [Causes of maternal mortality in the Instituto Mexicano del Seguro Social, period 2009-2012].

    PubMed

    Ruíz-Rosas, Roberto Aguli; Cruz-Cruz, Polita Rocío

    2014-01-01

    Introducción: la razón de muerte materna (RMM) ha disminuido lentamente, no obstante que la OMS se propuso reducirla en un 75 % en el período de 1990 a 2015. Por esto es necesario continuar con el análisis de las causas para reforzar e innovar líneas de acción y así disminuir las muertes maternas en nuestro país. Métodos: estudio retrospectivo en el que se incluyeron casos de muerte materna que ocurrieron de 2009 a 2012, por causa directa e indirecta. La información se obtuvo del expediente de muerte materna, el cual es un documento oficial del IMSS. La definición de muerte materna utilizada fue la emitida por la OMS. Las muertes indirectas se agruparon según la décima revisión de la Clasificación Internacional de Enfermedades (CIE-10). Se utilizó estadística descriptiva. Resultados: la RMM en el IMSS ha disminuido en forma lenta pero constante, pues en el 2012 se obtuvo la RMM más baja en la institución (26.4). Sin embargo, la preeclampsia severa-eclampsia y la hemorragia obstétrica ocuparon el primero y segundo lugar. Como causa indirecta, las enfermedades del sistema cardiovascular, y las neoplasias malignas ocuparon los primeros lugares sin subestimar las cifras de las patologías respiratorias, digestivas y endocrinas. Conclusiones: es necesario proseguir con los esfuerzos para disminuir la RMM en todos los niveles de atención médica. Es prioritario continuar con la educación y consejería preconcepcional a mujeres en edad fértil y fortalecer las acciones en la planificación familiar.

  7. Detection of the deltaF508 (F508del) mutation of the cystic fibrosis gene by surface plasmon resonance and biosensor technology.

    PubMed

    Feriotto, G; Lucci, M; Bianchi, N; Mischiati, C; Gambari, R

    1999-01-01

    In the present paper, we applied surface plasmon resonance (SPR) and biosensor technologies for biospecific interaction analysis (BIA) to detect deltaF508 mutation (F508del) of the cystic fibrosis transmembrane regulator (CFTR) gene in both homozygous as well as heterozygous human subjects. The proposed method is divided into three major steps. The first step is the immobilization on a SA5 sensor chip of two biotinylated oligonucleotide probes (one normal, N-508, and the other mutant, deltaF508) that are able to hybridize to the CFTR gene region involved in F508del mutation. The second step consists of the molecular hybridization between the oligonucleotide probes immobilized on the sensor chips and (1) wild-type or mutant oligonucleotides, as well as (2) single-stranded DNA obtained by asymmetric polymerase chain reaction (PCR), performed using genomic DNA from normal individuals and from F508del heterozygous and F508del homozygous patients. The third, and most important, step consists of the evaluation of differential stabilities of DNA/DNA molecular complexes generated after hybridization of normal and deltaF508 probes immobilized on the sensor chips. The results obtained strongly suggest that the proposed procedure employing SPR technology enables a one-step, nonradioactive protocol for the molecular diagnosis of F508del mutation of the CFTR gene. This approach could be of interest in clinical genetics, as the hybridization step is oftenly required to detect microdeletions present within PCR products.

  8. Light and redox switchable molecular components for molecular electronics.

    PubMed

    Browne, Wesley R; Feringa, Ben L

    2010-01-01

    The field of molecular and organic electronics has seen rapid progress in recent years, developing from concept and design to actual demonstration devices in which both single molecules and self-assembled monolayers are employed as light-responsive components. Research in this field has seen numerous unexpected challenges that have slowed progress and the initial promise of complex molecular-based computers has not yet been realised. Primarily this has been due to the realisation at an early stage that molecular-based nano-electronics brings with it the interface between the hard (semiconductor) and soft (molecular) worlds and the challenges which accompany working in such an environment. Issues such as addressability, cross-talk, molecular stability and perturbation of molecular properties (e.g., inhibition of photochemistry) have nevertheless driven development in molecular design and synthesis as well as our ability to interface molecular components with bulk metal contacts to a very high level of sophistication. Numerous groups have played key roles in progressing this field not least teams such as those led by Whitesides, Aviram, Ratner, Stoddart and Heath. In this short review we will however focus on the contributions from our own group and those of our collaborators, in employing diarylethene based molecular components.

  9. Produccion Gaseosa del Cometa Halley: Erupciones Y Fotodisociacion del Radical OH

    NASA Astrophysics Data System (ADS)

    Silva, A. M.; Mirabel, I. F.

    1990-11-01

    RESUMEN:En este trabajo informamos la detecci6n de 20 erupciones en la li'nea de =18cm (1667MHz) del radical OH en el Cometa Halley.Las observaciones incluyen todos los monitoreos existentes y se extienden desde 120 dias antes del perihelio hasta 90 dias despues.Se detectan bruscos crecimientos en el flujo medido,hasta un factor 1O,seguidos por decaimientos lentos asociados con la fotodisociaci6n del OH. Se obtuvieron valores para el tiempo de vida fotoquimico del OH y del H2O basandose en el modelo desarrollado previamente por Silva(1988). Esos tiempos de vida estan de acuerdo con predicciones teoricas y con las observaciones en el Ultravioleta, y los resultados, los que son fuertemente dependientes de la velocidad heliocentrica del Coineta (variando hasta un factor 6), han sido calculados para varios rangos de velocidad entre +28 y -28 km/seg. Key wo'L :

  10. Assessment of Molecular Modeling & Simulation

    SciTech Connect

    2002-01-03

    This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.

  11. Functional Rescue of F508del-CFTR Using Small Molecule Correctors

    PubMed Central

    Molinski, Steven; Eckford, Paul D. W.; Pasyk, Stan; Ahmadi, Saumel; Chin, Stephanie; Bear, Christine E.

    2012-01-01

    High-throughput screens for small molecules that are effective in “correcting” the functional expression of F508del-CFTR have yielded several promising hits. Two such compounds are currently in clinical trial. Despite this success, it is clear that further advances will be required in order to restore 50% or greater of wild-type CFTR function to the airways of patients harboring the F508del-CFTR protein. Progress will be enhanced by our better understanding of the molecular and cellular defects caused by the F508del mutation, present in 90% of CF patients. The goal of this chapter is to review the current understanding of defects caused by F508del in the CFTR protein and in CFTR-mediated interactions important for its biosynthesis, trafficking, channel function, and stability at the cell surface. Finally, we will discuss the gaps in our knowledge regarding the mechanism of action of existing correctors, the unmet need to discover compounds which restore proper CFTR structure and function in CF affected tissues and new strategies for therapy development. PMID:23055971

  12. Molecular biology references.

    PubMed

    2003-05-01

    Many of the units in this manual describe methods and techniques for the cloning, expression, and structural analysis of neural genes and proteins. We assume that users of these protocols have at least some introductory background in recombinant DNA technology (or are working with a collaborator who does); therefore, we have not provided comprehensive coverage of all of these topics, but rather have concentrated on presenting selected techniques that will be of the most interest and use to the general neuroscience laboratory. More comprehensive coverage of these topics can be found in Current Protocols in Molecular Biology (CPMB), which is extensively cross-referenced throughout this manual. These cross-references are summarized in this appendix.

  13. Molecular pathogenesis of emphysema.

    PubMed

    Taraseviciene-Stewart, Laimute; Voelkel, Norbert F

    2008-02-01

    Emphysema is one manifestation of a group of chronic, obstructive, and frequently progressive destructive lung diseases. Cigarette smoking and air pollution are the main causes of emphysema in humans, and cigarette smoking causes emphysema in rodents. This review examines the concept of a homeostatically active lung structure maintenance program that, when attacked by proteases and oxidants, leads to the loss of alveolar septal cells and airspace enlargement. Inflammatory and noninflammatory mechanisms of disease pathogenesis, as well as the role of the innate and adaptive immune systems, are being explored in genetically altered animals and in exposure models of this disease. These recent scientific advances support a model whereby alveolar destruction resulting from a coalescence of mechanical forces, such as hyperinflation, and more recently recognized cellular and molecular events, including apoptosis, cellular senescence, and failed lung tissue repair, produces the clinically recognized syndrome of emphysema.

  14. Molecular pathogenesis of emphysema

    PubMed Central

    Taraseviciene-Stewart, Laimute; Voelkel, Norbert F.

    2008-01-01

    Emphysema is one manifestation of a group of chronic, obstructive, and frequently progressive destructive lung diseases. Cigarette smoking and air pollution are the main causes of emphysema in humans, and cigarette smoking causes emphysema in rodents. This review examines the concept of a homeostatically active lung structure maintenance program that, when attacked by proteases and oxidants, leads to the loss of alveolar septal cells and airspace enlargement. Inflammatory and noninflammatory mechanisms of disease pathogenesis, as well as the role of the innate and adaptive immune systems, are being explored in genetically altered animals and in exposure models of this disease. These recent scientific advances support a model whereby alveolar destruction resulting from a coalescence of mechanical forces, such as hyperinflation, and more recently recognized cellular and molecular events, including apoptosis, cellular senescence, and failed lung tissue repair, produces the clinically recognized syndrome of emphysema. PMID:18246188

  15. GAS PHASE MOLECULAR DYNAMICS

    SciTech Connect

    SEARS,T.J.; HALL,G.E.; PRESES,J.M.; WESTON,R.E.,JR.

    1999-06-09

    The goal of this research is the understanding of elementary chemical and physical processes important in the combustion of fossil fuels. Interest centers on reactions involving short-lived chemical intermediates and their properties. High-resolution, high-sensitivity, laser absorption methods are augmented by high temperature flow-tube reaction kinetics studies with mass-spectrometric sampling. These experiments provide information on the energy levels, structures and reactivity of molecular free radical species and, in turn, provide new tools for the study of energy flow and chemical bond cleavage in the radicals in chemical systems. The experimental work is supported by theoretical and computational work using time-dependent quantum wavepacket calculations that provide insights into energy flow between the vibrational modes of the molecule. The work of group members Fockenberg and Muckerman is described in separate abstracts of this volume.

  16. Molecular mechanisms of carcinogenesis

    SciTech Connect

    Hall, E.J.

    1997-03-01

    The possibility that chromosomal changes are responsible for neoplasia was proposed in the early years of this century. A combination of improved cytogenetics and the advent of recombinant technology has settled the issue. As recently as 20 years ago, however, the genetic and molecular basis of familiar predisposition to cancer were a mystery, and it is only in the last few years that light has been shed on a few specific types of malignancies. As the genetic basis of human cancer had been documented, a number of genes have been identified as functioning either as oncogenes which act in a dominant fashion to promote tumor growth when mutated, or as tumor suppressor genes which act in a recessive fashion.

  17. [Molecular genetics of hypercholesterolemia].

    PubMed

    Schwarzová, Lucie

    2016-01-01

    The review focuses on the molecular background of an inborn error of lipid metabolism -familial hypercholesterolemia. FH describes a group of genetic defects resulting in severe elevations of blood cholesterol levels and increased risk of premature coronary heart disease. Most cases are due to the mutations decreasing and/or destroying the function of the LDL receptor (85-90 % of cases), smaller portion of cases is caused by defects in the gene encoding the ligand for LDL receptor - apolipoprotein B-100 (5-10 %). Less than 5 % of cases has gain-of-function station of the PCSK9 gene that increases the rate of degradation of the LDL receptor molecules. Autosomal recessive form of the disease, caused by the mutations in LDLR adaptor protein 1 gene, is extremely rare.Key words: APOB - familial hypercholesterolemia - LDLR - LDLRAP1 - PCSK9.

  18. Methods in molecular cardiology

    PubMed Central

    de Theije, C.C.; de Windt, L.J.; Doevendans, P.A.

    2002-01-01

    Sequencing is one the major breakthroughs in molecular cardiology. The development of this technique has made it possible to determine the exact order of the nucleotides in DNA. The exact order is relevant for the formation of proteins, through the genetic code. Sequencing is even more important for the identification of genetic variation and disease-causing mutations. The elucidation of the human genome is based on the continuous improvement of this technique, reducing the cost and increasing efficiency. Initially, complex chemical reactions were performed using isotopes to unravel the base sequence in genes. Nowadays, fluorescent capillary-based techniques are available to determine the genetic information. Here, the historical development of the technique is described. In addition, examples are provided on how sequencing is used in clinical medicine. ImagesFigure 2Figure 3Figure 8Figure 9 PMID:25696079

  19. Molecular Dynamics Calculations

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The development of thermodynamics and statistical mechanics is very important in the history of physics, and it underlines the difficulty in dealing with systems involving many bodies, even if those bodies are identical. Macroscopic systems of atoms typically contain so many particles that it would be virtually impossible to follow the behavior of all of the particles involved. Therefore, the behavior of a complete system can only be described or predicted in statistical ways. Under a grant to the NASA Lewis Research Center, scientists at the Case Western Reserve University have been examining the use of modern computing techniques that may be able to investigate and find the behavior of complete systems that have a large number of particles by tracking each particle individually. This is the study of molecular dynamics. In contrast to Monte Carlo techniques, which incorporate uncertainty from the outset, molecular dynamics calculations are fully deterministic. Although it is still impossible to track, even on high-speed computers, each particle in a system of a trillion trillion particles, it has been found that such systems can be well simulated by calculating the trajectories of a few thousand particles. Modern computers and efficient computing strategies have been used to calculate the behavior of a few physical systems and are now being employed to study important problems such as supersonic flows in the laboratory and in space. In particular, an animated video (available in mpeg format--4.4 MB) was produced by Dr. M.J. Woo, now a National Research Council fellow at Lewis, and the G-VIS laboratory at Lewis. This video shows the behavior of supersonic shocks produced by pistons in enclosed cylinders by following exactly the behavior of thousands of particles. The major assumptions made were that the particles involved were hard spheres and that all collisions with the walls and with other particles were fully elastic. The animated video was voted one of two

  20. W3 molecular cloud

    SciTech Connect

    Thronson, H.A.,JR.; Lada, C.J.; Hewagama, T.

    1985-10-01

    Extensive J = 1 to 0 (C-12)(O-16) and (C-13)(O-16) observations of the W3 molecular cloud and the surrounding region are presented and discussed. The velocity structure in the region is strongly suggestive of a model of large-scale, externally induced star formation. It is shown that star formation occurred in W3 and the nearby star-forming region W3(OH) after the gas within which they lie was swept up by the expanding W4 ionization front. Two condensations dominate the mass structure of the core of W3, one associated with IRS 4 and the other with IRS 5 and 1. A velocity difference between the two condensations is interpreted as indicating the two sources actually are discrete knots. 31 references.

  1. Molecular Diagnosis for Breast Malignancy

    DTIC Science & Technology

    1997-07-01

    AD GRANT NUMBER DAMD17-94-J-4033 TITLE: Molecular Diagnosis for Breast Malignancy PRINCIPAL INVESTIGATOR: Wen-Tien Chen, Ph.D. CONTRACTING...Biomedical Laboratories. - Signature -^yjgf Wen-Tien Chen, Ph.D. Page 4 Molecular diagnosis for breast malignancy (1) FRONT COVER: (2) SF 298...June 8-9, 1995 (abstract). Chen, W.-T, Goldstein LA, Pineiro-Sänchez M, Howard L, Ghersi G, Salamone M, Flessate D, Yeh Y. 1977. " Molecular Diagnosis for

  2. Molecular Cloning of Adenosinediphosphoribosyl Transferase.

    DTIC Science & Technology

    1987-09-08

    ACCESSION NO.D,. 03261102F 2312 A~5 11. TITLE (include Securqt Classification) 0 Molecular Cloning of Adenosinediphosphoribosyl Transferase 12. PERSONAL...I’:- AFOSR.Tlt. 8 7 - 0 9 8,2 0IL * pi AFOSR- 85 -0377 PROGRESS REPORT Molecular Cloning of Adenosinediphosphoribosyl Transferase 5." Period of...Pharmacology and the Cardiovascular Research Institute September 8, 1987 .’, 5.’- "’S ". -f, AFOSR - 85 -0377 PROGRESS REPORT Molecular Cloning of

  3. Molecular biology of atherosclerosis

    PubMed Central

    Mannarino, Elmo; Pirro, Matteo

    2008-01-01

    The traditional view of atherosclerosis as a pathological lipid deposition within the artery wall has been redefined by a more complex concept of an ongoing inflammatory disease. The atherosclerotic process is initiated when cardiovascular risk factors, through a chemical, mechanical or immunological insult, activate and/or injury the endothelium, thus contributing to endothelial dysfunction and fragmentation. This triggers a cascade of inflammatory reactions, in which monocytes, macrophages, T lymphocytes, vascular smooth muscle cells actively participate. Particularly, atherosclerotic lesions have been seen to have increased expression of T helper-1 cells together with increased levels of the T helper-1 related pro-inflammatory cytokines. Along with pro-inflammatory cytokines, other molecular factors involved in atherosclerosis appearance, progression and complication include chemokines, growth factors, vasoactive substances, enzymes, apoptosis signals and many others. Many of these molecular factors are both involved as possible markers of the atherosclerotic disease activity and burden, but may also play a crucial role in the pathogenesis of the disease. In recent years, the discovery of progenitor cells of myeloid origin has offered the prospect of merging the most recent theories on the pathogenesis of atherosclerosis with the evolving concept of a role of these progenitor cells in the repair of the injured vessel wall and the neovascularisation of ischemic tissues. This review summarizes current knowledge about the biology of atherosclerosis with emphasis on the mechanisms of endothelial damage and repair and on the concept that the turnover and replacement of endothelial cells is a major determinant in the maintenance of vascular integrity. PMID:22460847

  4. [Neurocience in the Junta para Ampliación de Estudios].

    PubMed

    Díaz, Alfredo Baratas

    2007-01-01

    The development of the Neurociencias in the Spain at the first third of the 20th century had a strong histological and pathological component. The work of Santiago Ramon and Cajal and Luis Simarro was continued by some excellent disciples: Nicolas Achúcarro, Gonzalo Rodriguez Lafora, Fernando de Castro, etc. Some of them had to make compatible diverse occupations, even the professional exercise of psychiatry, before obtaining a modest - but stable - position of investigation. In spite of some misalignments in the institutional development of the centers and the personal biographical ups and downs, the Junta para Ampliación de Estudios was the great institution that fomented the international formation of the investigators and equipped to them with the means to develop its work.

  5. New clinical and molecular insights on Barth syndrome

    PubMed Central

    2013-01-01

    Background Barth syndrome (BS) is an X-linked infantile-onset cardioskeletal disease characterized by cardiomyopathy, hypotonia, growth delay, neutropenia and 3-methylglutaconic aciduria. It is caused by mutations in the TAZ gene encoding tafazzin, a protein involved in the metabolism of cardiolipin, a mitochondrial-specific phospholipid involved in mitochondrial energy production. Methods Clinical, biochemical and molecular characterization of a group of six male patients suspected of having BS. Three patients presented early with severe metabolic decompensation including respiratory distress, oxygen desaturation and cardiomyopathy and died within the first year of life. The remaining three patients had cardiomyopathy, hypotonia and growth delay and are still alive. Cardiomyopathy was detected during pregnancy through a routine check-up in one patient. All patients exhibited 3-methylglutaconic aciduria and neutropenia, when tested and five of them also had lactic acidosis. Results We confirmed the diagnosis of BS with sequence analysis of the TAZ gene, and found five new mutations, c.641A>G p.His214Arg, c.284dupG (p.Thr96Aspfs*37), c.678_691del14 (p.Tyr227Trpfs*79), g.8009_16445del8437 and g.[9777_9814del38; 9911-?_14402del] and the known nonsense mutation c.367C>T (p.Arg123Term). The two gross rearrangements ablated TAZ exons 6 to 11 and probably originated by non-allelic homologous recombination and by Serial Replication Slippage (SRS), respectively. The identification of the breakpoints boundaries of the gross deletions allowed the direct detection of heterozygosity in carrier females. Conclusions Lactic acidosis associated with 3-methylglutaconic aciduria is highly suggestive of BS, whilst the severity of the metabolic decompensation at disease onset should be considered for prognostic purposes. Mutation analysis of the TAZ gene is necessary for confirming the clinical and biochemical diagnosis in probands in order to identify heterozygous carriers and

  6. Interface-assisted molecular spintronics

    NASA Astrophysics Data System (ADS)

    Raman, Karthik V.

    2014-09-01

    Molecular spintronics, a field that utilizes the spin state of organic molecules to develop magneto-electronic devices, has shown an enormous scientific activity for more than a decade. But, in the last couple of years, new insights in understanding the fundamental phenomena of molecular interaction on magnetic surfaces, forming a hybrid interface, are presenting a new pathway for developing the subfield of interface-assisted molecular spintronics. The recent exploration of such hybrid interfaces involving carbon based aromatic molecules shows a significant excitement and promise over the previously studied single molecular magnets. In the above new scenario, hybridization of the molecular orbitals with the spin-polarized bands of the surface creates new interface states with unique electronic and magnetic character. This study opens up a molecular-genome initiative in designing new handles to functionalize the spin dependent electronic properties of the hybrid interface to construct spin-functional tailor-made devices. Through this article, we review this subject by presenting a fundamental understanding of the interface spin-chemistry and spin-physics by taking support of advanced computational and spectroscopy tools to investigate molecular spin responses with demonstration of new interface phenomena. Spin-polarized scanning tunneling spectroscopy is favorably considered to be an important tool to investigate these hybrid interfaces with intra-molecular spatial resolution. Finally, by addressing some of the recent findings, we propose novel device schemes towards building interface tailored molecular spintronic devices for applications in sensor, memory, and quantum computing.

  7. Molecular Epidemiology of Foodborne Pathogens

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Brown, Eric; Knabel, Stephen J.

    The purpose of this chapter is to describe the basic principles and advancements in the molecular epidemiology of foodborne pathogens. Epidemiology is the study of the distribution and determinants of infectious diseases and/or the dynamics of disease transmission. The goals of epidemiology include the identification of physical sources, routes of transmission of infectious agents, and distribution and relationships of different subgroups. Molecular epidemiology is the study of epidemiology at the molecular level. It has been defined as "a science that focuses on the contribution of potential genetic and environmental risk factors, identified at the molecular level, to the etiology, distribution and prevention of diseases within families and across populations".

  8. Interface-assisted molecular spintronics

    SciTech Connect

    Raman, Karthik V.

    2014-09-15

    Molecular spintronics, a field that utilizes the spin state of organic molecules to develop magneto-electronic devices, has shown an enormous scientific activity for more than a decade. But, in the last couple of years, new insights in understanding the fundamental phenomena of molecular interaction on magnetic surfaces, forming a hybrid interface, are presenting a new pathway for developing the subfield of interface-assisted molecular spintronics. The recent exploration of such hybrid interfaces involving carbon based aromatic molecules shows a significant excitement and promise over the previously studied single molecular magnets. In the above new scenario, hybridization of the molecular orbitals with the spin-polarized bands of the surface creates new interface states with unique electronic and magnetic character. This study opens up a molecular-genome initiative in designing new handles to functionalize the spin dependent electronic properties of the hybrid interface to construct spin-functional tailor-made devices. Through this article, we review this subject by presenting a fundamental understanding of the interface spin-chemistry and spin-physics by taking support of advanced computational and spectroscopy tools to investigate molecular spin responses with demonstration of new interface phenomena. Spin-polarized scanning tunneling spectroscopy is favorably considered to be an important tool to investigate these hybrid interfaces with intra-molecular spatial resolution. Finally, by addressing some of the recent findings, we propose novel device schemes towards building interface tailored molecular spintronic devices for applications in sensor, memory, and quantum computing.

  9. Estudio espectroscópico de la simbiótica CD-43o14304

    NASA Astrophysics Data System (ADS)

    García, L. G.; Brandi, E.; Ferrer, O. E.; Barbá, R.

    En base a un monitoreo espectroscópico de estrellas simbióticas del hemisferio sur, realizado entre 1990 y 1997, se han reunido espectros en intermedia y alta resolución de la simbiótica CD-43o14304. Se trata de un sistema binario compuesto por una enana blanca y una gigante tipo K5 con un período orbital recientemente determinado, de 1448 días. Por primera vez se analiza el comportamiento espectral del objeto en un amplio rango espectral (3700-10000 Å) y en función de las fases orbitales observadas. Se interpretan las velocidades radiales de las emisiones y absorciones presentes y las variaciones en los perfiles estructurados de las líneas de Balmer y en el resto de las emisiones.

  10. Targeted re-sequencing analysis of 25 genes commonly mutated in myeloid disorders in del(5q) myelodysplastic syndromes

    PubMed Central

    Fernandez-Mercado, Marta; Burns, Adam; Pellagatti, Andrea; Giagounidis, Aristoteles; Germing, Ulrich; Agirre, Xabier; Prosper, Felipe; Aul, Carlo; Killick, Sally; Wainscoat, James S.; Schuh, Anna; Boultwood, Jacqueline

    2013-01-01

    Interstitial deletion of chromosome 5q is the most common chromosomal abnormality in myelodysplastic syndromes. The catalogue of genes involved in the molecular pathogenesis of myelodysplastic syndromes is rapidly expanding and next-generation sequencing technology allows detection of these mutations at great depth. Here we describe the design, validation and application of a targeted next-generation sequencing approach to simultaneously screen 25 genes mutated in myeloid malignancies. We used this method alongside single nucleotide polymorphism-array technology to characterize the mutational and cytogenetic profile of 43 cases of early or advanced del(5q) myelodysplastic syndromes. A total of 29 mutations were detected in our cohort. Overall, 45% of early and 66.7% of advanced cases had at least one mutation. Genes with the highest mutation frequency among advanced cases were TP53 and ASXL1 (25% of patients each). These showed a lower mutation frequency in cases of 5q- syndrome (4.5% and 13.6%, respectively), suggesting a role in disease progression in del(5q) myelodysplastic syndromes. Fifty-two percent of mutations identified were in genes involved in epigenetic regulation (ASXL1, TET2, DNMT3A and JAK2). Six mutations had allele frequencies <20%, likely below the detection limit of traditional sequencing methods. Genomic array data showed that cases of advanced del(5q) myelodysplastic syndrome had a complex background of cytogenetic aberrations, often encompassing genes involved in myeloid disorders. Our study is the first to investigate the molecular pathogenesis of early and advanced del(5q) myelodysplastic syndromes using next-generation sequencing technology on a large panel of genes frequently mutated in myeloid malignancies, further illuminating the molecular landscape of del(5q) myelodysplastic syndromes. PMID:23831921

  11. Molecular characteristics of some commercial high-molecular-weight hyaluronans.

    PubMed

    Soltés, L; Mendichi, R; Lath, D; Mach, M; Bakos, D

    2002-10-01

    Commercially available hyaluronan (HA) samples were investigated by the method of size exclusion chromatography (SEC). The fractions eluted from the SEC column were on-line molecularly characterized by using a multi-angle laser light scattering (MALLS) photometer. Along with the SEC-MALLS technique, the high-molecular-weight HA biopolymers were (off-line) analyzed by capillary viscometry.

  12. Molecular Weight and Molecular Weight Distributions in Synthetic Polymers.

    ERIC Educational Resources Information Center

    Ward, Thomas Carl

    1981-01-01

    Focuses on molecular weight and molecular weight distributions (MWD) and models for predicting MWD in a pedagogical way. In addition, instrumental methods used to characterize MWD are reviewed with emphasis on physical chemistry of each, including end-group determination, osmometry, light scattering, solution viscosity, fractionation, and…

  13. Molecular rheology of perfluoropolyether lubricant via nonequilibrium molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Guo, Qian; Chung, Pil Seung; Chen, Haigang; Jhon, Myung S.

    2006-04-01

    Molecular rheology of perfluoropolyether (PFPE) systems is particularly important in designing effective lubricants that control the friction and wear in tribological applications. Using the coarse-grained, bead-spring model, equilibrium molecular dynamics based on the Langevin equation in a quiescent flow was first employed to examine the nanostructure of PFPE. Further, by integrating the modified Langevin equation and imposing the Lees-Edwards boundary condition, nonequilibrium molecular dynamics of steady shear was investigated. We observe that the shear viscosity of PFPE system depends strongly on molecular architecture (e.g., molecular weight and endgroup functionality) and external conditions (e.g., temperature and shear rate). Our study of the flow activation energy/entropy and their correlations with nanostructure visualization showed that the PFPE structure was substantially modified.

  14. Tratamiento Quirúrgico de los Meningiomas del Foramen Óptico, Técnicay Resultados de una Serie de 18 Pacientes

    PubMed Central

    Goldschmidt, Ezequiel; Ajler, Pablo; Campero, Álvaro; Landriel, Federico; Sposito, Maximiliano; Carrizo, Antonio

    2014-01-01

    Introducción: los meningiomas del foramen óptico producen un rápido deterioro de la función visual aún cuando su tamaño es pequeño, por eso su diagnóstico y manejo difiere del resto de los meningiomas clinoideos. El propósito de este estudio es presentar la técnica y los resultados de nuestro manejo quirúrgico de meningiomas foraminales (MF). Pacientes y Métodos: se llevó a cabo una revisión de las historias clínicas de 47 pacientes con meningiomas primarios intraorbitarios. Se realizaron 52 cirugías en los pacientes con MF. Se empleó una craneotomía fronto-orbitaria, seguida de una descompresión extradural del canal óptico, resección del componente intraorbitario y exploración intradural del nervio óptico. Resultados: de los 12 pacientes con MF que presentaban la visión conservada, la agudeza visual fue preservada en 7 casos, mejoró en 2, y empeoró en 3. En 18 pacientes, el principal síntoma fue exoftalmos y en 35 pacientes ceguera unilateral. Ocurrieron 6 recurrencias, 2 a 10 años después de la resección quirúrgica. Cinco de ellos fueron reoperados. Se indicó radioterapia después de la recurrencia en 3 pacientes. Conclusión: el manejo de los MF continúa siendo controvertido y frecuentemente se propone un tratamiento conservador. Basados en nuestros hallazgos de frecuente extensión intracraneal, proponemos realizar una resección total o subtotal del tumor, preservando el nervio óptico en pacientes con visión prequirúrgica conservada. PMID:25165616

  15. Molecular study of patients with auditory neuropathy.

    PubMed

    Carvalho, Guilherme Machado De; Ramos, Priscila Zonzini; Castilho, Arthur Menino; Guimarães, Alexandre Caixeta; Sartorato, Edi Lúcia

    2016-07-01

    Auditory neuropathy is a type of hearing loss that constitutes a change in the conduct of the auditory stimulus by the involvement of inner hair cells or auditory nerve synapses. It is characterized by the absence or alteration of waves in the examination of brainstem auditory evoked potentials, with otoacoustic and/or cochlear microphonic issues. At present, four loci associated with non‑syndromic auditory neuropathy have been mapped: Autosomal recessive deafness‑9 [DFNB9; the otoferlin (OTOF) gene] and autosomal recessive deafness‑59 [DFNB59; the pejvakin (PJVK) gene], associated with autosomal recessive inheritance; the autosomal dominant auditory neuropathy gene [AUNA1; the diaphanous‑3 (DIAPH3) gene]; and AUNX1, linked to chromosome X. Furthermore, mutations of connexin 26 [the gap junction β2 (GJB2) gene] have also been associated with the disease. OTOF gene mutations exert a significant role in auditory neuropathy. In excess of 80 pathogenic mutations have been identified in individuals with non‑syndromic deafness in populations of different origins, with an emphasis on the p.Q829X mutation, which was found in ~3% of cases of deafness in the Spanish population. The identification of genetic alterations responsible for auditory neuropathy is one of the challenges contributing to understand the molecular bases of the different phenotypes of hearing loss. Thus, the present study aimed to investigate molecular changes in the OTOF gene in patients with auditory neuropathy, and to develop a DNA chip for the molecular diagnosis of auditory neuropathy using mass spectrometry for genotyping. Genetic alterations were investigated in 47 patients with hearing loss and clinical diagnosis of auditory neuropathy, and the c.35delG mutation in the GJB2 gene was identified in three homozygous patients, and the heterozygous parents of one of these cases. Additionally, OTOF gene mutations were tracked by complete sequencing of 48 exons, although these results

  16. [Genetics and the Junta para Ampliación de Estudios e Investigaciones Científicas].

    PubMed

    Peláez, Raquel Alvarez

    2007-01-01

    The aim of this paper is to show the essential paper developed by the Junta para Ampliación de Estudios in the origin of the Spanish genetics, using for that the most relevant researchers of the time, and between them two women, Jimena Fernández de la Vega and Käte Pariser.

  17. First Steps in the Development of the Inventario de Comportamiento de Estudio: The Spanish Version of the Study Behavior Inventory

    ERIC Educational Resources Information Center

    Bliss, Leonard B.; Vinay, Diana Maria Alejandra

    2004-01-01

    The Inventario de Comportamiento de Estudio (ICE), a Spanish version of the Study Behavior Inventory (SBI), was developed and tested using 594 undergraduate students at la Universidad de las Americas, in the state of Puebla, Mexico. A team of bilingual specialists was assembled to produce a translation that might be generic enough to be understood…

  18. First Steps in the Development of the "Inventario de Comportamiento de Estudio": The Spanish Version of the "Study Behavior Inventory."

    ERIC Educational Resources Information Center

    Bliss, Leonard B.; And Others

    The Inventario de Comportamiento de Estudio (ICE), a Spanish translation of the Study Behavior Inventory (SBI) was developed and tested using a group of 594 undergraduate students from randomly selected classes at a private comprehensive university in Mexico. Both instruments were designed to assess the study behaviors of students in institutions…

  19. HIV Molecular Immunology 2015

    SciTech Connect

    Yusim, Karina; Korber, Bette Tina; Brander, Christian; Barouch, Dan; de Boer, Rob; Haynes, Barton F.; Koup, Richard; Moore, John P.; Walker, Bruce D.; Watkins, David

    2016-04-05

    The scope and purpose of the HIV molecular immunology database: HIV Molecular Immunology is a companion volume to HIV Sequence Compendium. This publication, the 2015 edition, is the PDF version of the web-based HIV Immunology Database (http://www.hiv.lanl.gov/ content/immunology/). The web interface for this relational database has many search options, as well as interactive tools to help immunologists design reagents and interpret their results. In the HIV Immunology Database, HIV-specific B-cell and T-cell responses are summarized and annotated. Immunological responses are divided into three parts, CTL, T helper, and antibody. Within these parts, defined epitopes are organized by protein and binding sites within each protein, moving from left to right through the coding regions spanning the HIV genome. We include human responses to natural HIV infections, as well as vaccine studies in a range of animal models and human trials. Responses that are not specifically defined, such as responses to whole proteins or monoclonal antibody responses to discontinuous epitopes, are summarized at the end of each protein section. Studies describing general HIV responses to the virus, but not to any specific protein, are included at the end of each part. The annotation includes information such as cross-reactivity, escape mutations, antibody sequence, TCR usage, functional domains that overlap with an epitope, immune response associations with rates of progression and therapy, and how specific epitopes were experimentally defined. Basic information such as HLA specificities for T-cell epitopes, isotypes of monoclonal antibodies, and epitope sequences are included whenever possible. All studies that we can find that incorporate the use of a specific monoclonal antibody are included in the entry for that antibody. A single T-cell epitope can have multiple entries, generally one entry per study. Finally, maps of all defined linear epitopes relative to the HXB2 reference proteins

  20. Molecular Processes in Comets

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1998-01-01

    The research focused on molecular hydrogen and its response to ultraviolet radiation, photoelectron impact excitation and X-ray radiation and on the interpretation of the ultraviolet spectra of the Jupiter dayglow and auroras. A systematic effort was made to obtain reliable rate coefficients for rovibrational energy transfer of H2, particularly in collisions with hydrogen atoms. We carried out elaborate quantum-mechanical calculations of the scattering of H and H2 on what had been characterized as a reliable potential energy surface of the H3 molecular system. These calculations took into account reactive channels and rate coefficients for ortho-para transitions were obtained. Quantal calculations are too complex to be applied to all the possible rovibrational transitions and we turned to a semi-classical method. With it we calculated rate coefficients for transitions, reactive and non-reactive, for all the rovibrational levels. We carried out the calculations for three of the available H3 potential energy surfaces. We discovered an unexpected sensitivity of the rate coefficients for the non-reactive channels to the potential energy surface. This discovery stimulated more thorough investigations of the potential energy surface elsewhere and to the construction of a new surface. We have used it in further semi-classical calculations in work that will shortly be 2 completed and which, together with new quantum-mechanical calculations should comprise a set of reliable rate coefficients that can be used in discussions of H2 on the Jovian planets. We carried out a detailed study of the Jovian ultraviolet dayglow. There has been a long-running argument about the dayglow on Jupiter. There are two sources of excitation: fluorescence and photoelectron impact excitation. It had been argued that a third source "the electron glow" was needed to bring theory and observation into agreement. We believe we have shown conclusively that the third source is unnecessary. We have

  1. [PREVALENCE OF METABOLIC SYNDROME AMONG THE STAFF OF UNIVERSIDAD INTERNACIONAL DEL ECUADOR, HEADQUARTERS, PERIOD 2014-2015].

    PubMed

    Viteri Holguín, María Paula; Castro Burbano, José

    2015-12-01

    Introducción: el síndrome metabólico es un conjunto de alteraciones metabólicas que incrementan el riesgo de desarrollar diabetes tipo 2 y enfermedades cardiovasculares. Existen varios criterios para su diagnóstico, entre ellos los más utilizados son el de la Federación Internacional de Diabetes (IDF) y el del Panel de Tratamiento de Adultos III (ATP III). Un tratamiento oportuno puede evitar las complicaciones asociadas y mejorar la calidad y esperanza de vida del paciente, que debe ser enfocado a realizar modificaciones en el estilo de vida, como una alimentación saludable y actividad física regular. Objetivo: determinar la prevalencia de síndrome metabólico según los criterios de diagnóstico de la Federación Internacional de Diabetes (IDF) y del Panel de Tratamiento de Adultos III (ATP III). Metodología: es un estudio de corte transversal en el cual participaron 128 personas (55 mujeres y 73 hombres) de entre 18 y 75 años de edad, a quienes se les realizó una historia nutricional, medidas antropométricas y exámenes bioquímicos. Resultados: la prevalencia de exceso de peso fue del 63% (sobrepeso 48% y obesidad 15%). La prevalencia de síndrome metabólico según IDF fue 15,6% y según ATPIII 14,8%. Conclusiones: en el personal evaluado, es evidente la alta prevalencia de exceso de peso y síndrome metabólico, por lo que es prioritario trabajar en la implementación de medidas preventivas para detener su progresión y el desarrollo de complicaciones cardiometabólicas.

  2. Optically controllable molecular logic circuits

    SciTech Connect

    Nishimura, Takahiro Fujii, Ryo; Ogura, Yusuke; Tanida, Jun

    2015-07-06

    Molecular logic circuits represent a promising technology for observation and manipulation of biological systems at the molecular level. However, the implementation of molecular logic circuits for temporal and programmable operation remains challenging. In this paper, we demonstrate an optically controllable logic circuit that uses fluorescence resonance energy transfer (FRET) for signaling. The FRET-based signaling process is modulated by both molecular and optical inputs. Based on the distance dependence of FRET, the FRET pathways required to execute molecular logic operations are formed on a DNA nanostructure as a circuit based on its molecular inputs. In addition, the FRET pathways on the DNA nanostructure are controlled optically, using photoswitching fluorescent molecules to instruct the execution of the desired operation and the related timings. The behavior of the circuit can thus be controlled using external optical signals. As an example, a molecular logic circuit capable of executing two different logic operations was studied. The circuit contains functional DNAs and a DNA scaffold to construct two FRET routes for executing Input 1 AND Input 2 and Input 1 AND NOT Input 3 operations on molecular inputs. The circuit produced the correct outputs with all possible combinations of the inputs by following the light signals. Moreover, the operation execution timings were controlled based on light irradiation and the circuit responded to time-dependent inputs. The experimental results demonstrate that the circuit changes the output for the required operations following the input of temporal light signals.

  3. Teaching Molecular Biology with Microcomputers.

    ERIC Educational Resources Information Center

    Reiss, Rebecca; Jameson, David

    1984-01-01

    Describes a series of computer programs that use simulation and gaming techniques to present the basic principles of the central dogma of molecular genetics, mutation, and the genetic code. A history of discoveries in molecular biology is presented and the evolution of these computer assisted instructional programs is described. (MBR)

  4. Classical and molecular genetic mapping

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A brief history of classical genetic mapping in soybean [Glycine max (L.) Merr.] is described. Detailed descriptions are given of the development of molecular genetic linkage maps based upon various types of DNA markers Like many plant and animal species, the first molecular map of soybean was bas...

  5. Chemical evolution of molecular clouds

    NASA Technical Reports Server (NTRS)

    Prasad, Sheo S.; Tarafdar, Sankar P.; Villere, Karen R.; Huntress, Wesley T., Jr.

    1987-01-01

    The principles behind the coupled chemical-dynamical evolution of molecular clouds are described. Particular attention is given to current problems involving the simplest species (i.e., C. CO, O2, and H2) in quiescent clouds. The results of a comparison made between the molecular abundances in the Orion ridge and the hot core (Blake, 1986) are presented.

  6. The Molecular Basis of Evolution.

    ERIC Educational Resources Information Center

    Wilson, Allan C.

    1985-01-01

    Discovery that mutations accumulate at steady rates over time in the genes of all lineages of plants and animals has led to new insights into evolution at the molecular and organismal levels. Discusses molecular evolution, examining deoxyribonuclei acid (DNA) sequences, morphological distances, and codon rate of change. (DH)

  7. Molecular ecology of aquatic microbes

    SciTech Connect

    1994-12-31

    Abstracts of reports are presented from a meeting on Molecular Ecology of Aquatic Microbes. Topics included: opportunities offered to aquatic ecology by molecular biology; the role of aquatic microbes in biogeochemical cycles; characterization of the microbial community; the effect of the environment on aquatic microbes; and the targeting of specific biological processes.

  8. Teaching Molecular 3-D Literacy

    ERIC Educational Resources Information Center

    Richardson, David C.; Richardson, Jane S.

    2002-01-01

    This article describes how the use of interactive molecular graphics makes a unique and important contribution to student learning of biochemistry and molecular biology at any level. These authors developed the concept of the kinemage (from "kinetic image"), a different way of organizing computer graphics that is aimed explicitly at the…

  9. Recent patents on molecular cytogenetics.

    PubMed

    Iourov, Ivan Y; Vorsanova, Svetlana G; Yurov, Yuri B

    2008-01-01

    The questions surrounding patenting of DNA sequences encoding specific proteins are relatively well reviewed in the available literature. However, neither applications nor molecular cytogenetic techniques, which use these sequences as a probe, have been reviewed in the light of the patenting. Furthermore, the patenting of the use of numerous probes, which are produced on different types of repetitive genome elements (i.e. satellite DNA or telomeric DNA sequences) and those generated by chromosome microdissection has not been reviewed. Molecular cytogenetic techniques are one of the most applied in current bioscience (as to June 2007, over 40,000 papers in browseable scientific databases mention one or several molecular cytogenetic techniques). Therefore, reviewing recent patents in this field is of general interest for numerous researchers in different areas of biology and medicine. Here, we address world-wide patents on DNA sequences used as molecular cytogenetic probes and molecular cytogenetic techniques to define current state and perspectives of this biomedical direction.

  10. Molecular beacon sequence design algorithm.

    PubMed

    Monroe, W Todd; Haselton, Frederick R

    2003-01-01

    A method based on Web-based tools is presented to design optimally functioning molecular beacons. Molecular beacons, fluorogenic hybridization probes, are a powerful tool for the rapid and specific detection of a particular nucleic acid sequence. However, their synthesis costs can be considerable. Since molecular beacon performance is based on its sequence, it is imperative to rationally design an optimal sequence before synthesis. The algorithm presented here uses simple Microsoft Excel formulas and macros to rank candidate sequences. This analysis is carried out using mfold structural predictions along with other free Web-based tools. For smaller laboratories where molecular beacons are not the focus of research, the public domain algorithm described here may be usefully employed to aid in molecular beacon design.

  11. Molecular chaperones and neuronal proteostasis

    PubMed Central

    Smith, Heather L.; Li, Wenwen; Cheetham, Michael E.

    2015-01-01

    Protein homeostasis (proteostasis) is essential for maintaining the functionality of the proteome. The disruption of proteostasis, due to genetic mutations or an age-related decline, leads to aberrantly folded proteins that typically lose their function. The accumulation of misfolded and aggregated protein is also cytotoxic and has been implicated in the pathogenesis of neurodegenerative diseases. Neurons have developed an intrinsic protein quality control network, of which molecular chaperones are an essential component. Molecular chaperones function to promote efficient folding and target misfolded proteins for refolding or degradation. Increasing molecular chaperone expression can suppress protein aggregation and toxicity in numerous models of neurodegenerative disease; therefore, molecular chaperones are considered exciting therapeutic targets. Furthermore, mutations in several chaperones cause inherited neurodegenerative diseases. In this review, we focus on the importance of molecular chaperones in neurodegenerative diseases, and discuss the advances in understanding their protective mechanisms. PMID:25770416

  12. Floating orbital molecular dynamics simulations.

    PubMed

    Perlt, Eva; Brüssel, Marc; Kirchner, Barbara

    2014-04-21

    We introduce an alternative ab initio molecular dynamics simulation as a unification of Hartree-Fock molecular dynamics and the floating orbital approach. The general scheme of the floating orbital molecular dynamics method is presented. Moreover, a simple but sophisticated guess for the orbital centers is provided to reduce the number of electronic structure optimization steps at each molecular dynamics step. The conservation of total energy and angular momentum is investigated in order to validate the floating orbital molecular dynamics approach with and without application of the initial guess. Finally, a water monomer and a water dimer are simulated, and the influence of the orbital floating on certain properties like the dipole moment is investigated.

  13. Electrostatic interactions in molecular materials

    NASA Astrophysics Data System (ADS)

    Painelli, Anna; Terenziani, Francesca

    2004-03-01

    Non-additive collective behavior appears in molecular materials as a result of intermolecular interactions. We present a model for interacting polar and polarizable molecules that applies to different supramolecular architectures of donor-π-acceptor molecules. We follow a bottom-up modeling strategy: the detailed analysis of spectroscopic data of solvated molecules leads to the definition of a simple two-state model for the molecular units. Classical electrostatic interactions are then introduced to model molecular clusters. The molecular properties are strickingly affected by supramolecular interactions, as demonstrated by spectroscopic studies. Brand new phenomena, like phase transitions and multielectron transfer, with no counterpart at the molecular level are observed as direct consequences of electrostatic intermolecular interactions.

  14. Molecular force spectroscopy on cells.

    PubMed

    Liu, Baoyu; Chen, Wei; Zhu, Cheng

    2015-04-01

    Molecular force spectroscopy has become a powerful tool to study how mechanics regulates biology, especially the mechanical regulation of molecular interactions and its impact on cellular functions. This force-driven methodology has uncovered a wealth of new information of the physical chemistry of molecular bonds for various biological systems. The new concepts, qualitative and quantitative measures describing bond behavior under force, and structural bases underlying these phenomena have substantially advanced our fundamental understanding of the inner workings of biological systems from the nanoscale (molecule) to the microscale (cell), elucidated basic molecular mechanisms of a wide range of important biological processes, and provided opportunities for engineering applications. Here, we review major force spectroscopic assays, conceptual developments of mechanically regulated kinetics of molecular interactions, and their biological relevance. We also present current challenges and highlight future directions.

  15. Photoacoustic molecular imaging

    NASA Astrophysics Data System (ADS)

    Kiser, William L., Jr.; Reinecke, Daniel; DeGrado, Timothy; Bhattacharyya, Sibaprasad; Kruger, Robert A.

    2007-02-01

    It is well documented that photoacoustic imaging has the capability to differentiate tissue based on the spectral characteristics of tissue in the optical regime. The imaging depth in tissue exceeds standard optical imaging techniques, and systems can be designed to achieve excellent spatial resolution. A natural extension of imaging the intrinsic optical contrast of tissue is to demonstrate the ability of photoacoustic imaging to detect contrast agents based on optically absorbing dyes that exhibit well defined absorption peaks in the infrared. The ultimate goal of this project is to implement molecular imaging, in which Herceptin TM, a monoclonal antibody that is used as a therapeutic agent in breast cancer patients that over express the HER2 gene, is labeled with an IR absorbing dye, and the resulting in vivo bio-distribution is mapped using multi-spectral, infrared stimulation and subsequent photoacoustic detection. To lay the groundwork for this goal and establish system sensitivity, images were collected in tissue mimicking phantoms to determine maximum detection depth and minimum detectable concentration of Indocyanine Green (ICG), a common IR absorbing dye, for a single angle photoacoustic acquisition. A breast mimicking phantom was constructed and spectra were also collected for hemoglobin and methanol. An imaging schema was developed that made it possible to separate the ICG from the other tissue mimicking components in a multiple component phantom. We present the results of these experiments and define the path forward for the detection of dye labeled Herceptin TM in cell cultures and mice models.

  16. Molecular factors in migraine

    PubMed Central

    Kowalska, Marta; Prendecki, Michał; Kozubski, Wojciech; Lianeri, Margarita; Dorszewska, Jolanta

    2016-01-01

    Migraine is a common neurological disorder that affects 11% of adults worldwide. This disease most likely has a neurovascular origin. Migraine with aura (MA) and more common form - migraine without aura (MO) – are the two main clinical subtypes of disease. The exact pathomechanism of migraine is still unknown, but it is thought that both genetic and environmental factors are involved in this pathological process. The first genetic studies of migraine were focused on the rare subtype of MA: familial hemiplegic migraine (FHM). The genes analysed in familial and sporadic migraine are: MTHFR, KCNK18, HCRTR1, SLC6A4, STX1A, GRIA1 and GRIA3. It is possible that migraine is a multifactorial disease with polygenic influence. Recent studies have shown that the pathomechanisms of migraine involves both factors responsible for immune response and oxidative stress such as: cytokines, tyrosine metabolism, homocysteine; and factors associated with pain transmission and emotions e.g.: serotonin, hypocretin-1, calcitonin gene-related peptide, glutamate. The correlations between genetic variants of the HCRTR1 gene, the polymorphism 5-HTTLPR and hypocretin-1, and serotonin were observed. It is known that serotonin inhibits the activity of hypocretin neurons and may affect the appearance of the aura during migraine attack. The understanding of the molecular mechanisms of migraine, including genotype-phenotype correlations, may contribute to finding markers important for the diagnosis and treatment of this disease. PMID:27191890

  17. Reverse engineering molecular hypergraphs.

    PubMed

    Rahman, Ahsanur; Poirel, Christopher L; Badger, David J; Estep, Craig; Murali, T M

    2013-01-01

    Analysis of molecular interaction networks is pervasive in systems biology. This research relies almost entirely on graphs for modeling interactions. However, edges in graphs cannot represent multiway interactions among molecules, which occur very often within cells. Hypergraphs may be better representations for networks having such interactions, since hyperedges can naturally represent relationships among multiple molecules. Here, we propose using hypergraphs to capture the uncertainty inherent in reverse engineering gene-gene networks. Some subsets of nodes may induce highly varying subgraphs across an ensemble of networks inferred by a reverse engineering algorithm. We provide a novel formulation of hyperedges to capture this uncertainty in network topology. We propose a clustering-based approach to discover hyperedges. We show that our approach can recover hyperedges planted in synthetic data sets with high precision and recall, even for moderate amount of noise. We apply our techniques to a data set of pathways inferred from genetic interaction data in S. cerevisiae related to the unfolded protein response. Our approach discovers several hyperedges that capture the uncertain connectivity of genes in relevant protein complexes, suggesting that further experiments may be required to precisely discern their interaction patterns. We also show that these complexes are not discovered by an algorithm that computes frequent and dense subgraphs.

  18. Cisplatin nephrotoxicity: molecular mechanisms

    PubMed Central

    Hanigan, Marie H.; Devarajan, Prasad

    2007-01-01

    Summary Cisplatin is one of the most widely used chemotherapeutic agents for the treatment of several human malignancies. The efficacy of cisplatin is dose dependent, but the significant risk of nephrotoxicity frequently hinders the use of higher doses to maximize its antineoplastic effects. Several advances in our understanding of the biochemical and molecular mechanisms underlying cisplatin nephrotoxicity have recently emerged, and are reviewed in this article. Evidence is presented for distinct mechanisms of cisplatin toxicity in actively dividing tumor cells versus the normally quiescent renal proximal tubular epithelial cells. The unexpected role of gamma-glutamyl transpeptidase in cisplatin nephrotoxicity is elucidated. Recent studies demonstrating the ability of proximal tubular cells to metabolize cisplatin to a nephrotoxin are reviewed. The evidence for apoptosis as a major mechanism underlying cisplatin-induced renal cell injury is presented, along with the data exploring the role of specific intracellular pathways that may mediate the programmed cell death. The information gleaned from this review may provide critical clues to novel therapeutic interventions aimed at minimizing cisplatin-induced nephrotoxicity while enhancing its antineoplastic efficacy. PMID:18185852

  19. Radically enhanced molecular recognition

    NASA Astrophysics Data System (ADS)

    Trabolsi, Ali; Khashab, Niveen; Fahrenbach, Albert C.; Friedman, Douglas C.; Colvin, Michael T.; Cotí, Karla K.; Benítez, Diego; Tkatchouk, Ekaterina; Olsen, John-Carl; Belowich, Matthew E.; Carmielli, Raanan; Khatib, Hussam A.; Goddard, William A.; Wasielewski, Michael R.; Stoddart, J. Fraser

    2010-01-01

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication.

  20. Molecular processes in comets

    NASA Technical Reports Server (NTRS)

    Dalgarno, A.

    1993-01-01

    Classical trajectory calculations of the cross sections for vibrational and rotational energy exchange in direct and reactive collisions of hydrogen atoms and hydrogen molecules have been carried out. To test the sensitivity, three potential energy surfaces have been used. For the exchange transitions which occur at small internuclear distances, the rate coefficients for the three surfaces agree quite well. For the direct transitions, there are significant differences for the pure rotational transitions from j=0 to 2 and from j=1 to j=3 in which there is no change in vibration. For higher j the differences tend to disappear, suggesting that the rotational angular momentum can couple to the orbital angular momentum to overcome the centrifugal barrier. Complete numerically exact quantum mechanical calculations for the process in which vJ changes have been performed. Dr. M. A'Hearn has provided data on the fluorescent population of the NH rotational and fine-structure levels from which we should be able to predict accurate photodissociation lifetimes. The distribution rate of C2 is being investigated. A review of H3(+) in terrestrial and extraterrestrial environments was prepared for a volume of Advances in Atomic, Molecular and Optical Physics.

  1. A Paramagnetic Molecular Voltmeter

    PubMed Central

    Surek, Jack T.; Thomas, David D.

    2008-01-01

    We have developed a general electron paramagnetic resonance (EPR) method to measure electrostatic potential at spin labels on proteins to millivolt accuracy. Electrostatic potential is fundamental to energy-transducing proteins like myosin, because molecular energy storage and retrieval is primarily electrostatic. Quantitative analysis of protein electrostatics demands a site-specific spectroscopic method sensitive to millivolt changes. Previous electrostatic potential studies on macromolecules fell short in sensitivity, accuracy and/or specificity. Our approach uses fast-relaxing charged and neutral paramagnetic relaxation agents (PRAs) to increase nitroxide spin label relaxation rate solely through collisional spin exchange. These PRAs were calibrated in experiments on small nitroxides of known structure and charge to account for differences in their relaxation efficiency. Nitroxide longitudinal (R1) and transverse (R2) relaxation rates were separated by applying lineshape analysis to progressive saturation spectra. The ratio of measured R1 increases for each pair of charged and neutral PRAs measures the shift in local PRA concentration due to electrostatic potential. Voltage at the spin label is then calculated using the Boltzmann equation. Measured voltages for two small charged nitroxides agree with Debye-Hückel calculations. Voltage for spin-labeled myosin fragment S1 also agrees with calculation based on the pK shift of the reacted cysteine. PMID:17964835

  2. Rigid molecular foams

    SciTech Connect

    Steckle, W.P. Jr.; Mitchell, M.A.; Aspen, P.G.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Organic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability, and processing. Rigid molecular foams or {open_quotes}organic zeolites{close_quotes} would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with dichloroxylene (DCX) as the pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15 g/cc to 0.75 g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and the crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m{sup 2}/g with pore sizes ranging from 6 {angstrom} to 2,000 {angstrom}.

  3. The Use of Blogs in English Language Learning: A Study of Student Perceptions (El uso de bitácoras o "blogs" en el aprendizaje del idioma inglés: un estudio sobre las percepciones del estudiante)

    ERIC Educational Resources Information Center

    Ahluwalia, Gurleen; Gupta, Deepti; Aggarwal, Deepak

    2011-01-01

    In this article we present an investigation that focused on the students' perception of using Blogs as a means to supplement in-class language learning activities. Blogs are easy to manage and enable students to publish their work in a chronological manner. They help students to engage in online exchanges and promote learner autonomy. This study…

  4. Abrahán Enseña astronomía: el prototipo bíblico del estudio del cómputo en las abadías Benedictinas de Cava de' Tirreni y Ripoll.

    NASA Astrophysics Data System (ADS)

    Castiñeiras González, M. A.

    In two miscellanies of computus from the abbeys of Cava de' Tirreni (XI century) and Santa María de Ripoll (XII century) an interesting illumination with the patriarch Abraham teaching three Egyptian disciples in secrets of cosmos was represented. The image, not documented in the Vulgata, is derived from a Jewish-Hellenistic tradition that presented Hebrews preceding Egyptians and Greeks in scientific knowledge. The representation of this subject is related to the teaching of astronomy in the Benedictine abbeys to determine the times (horas canonicae) and dates of Easter. But the Isidore's text which accompanies the illumination explains its real meaning: thanks to astrology, that had even practiced by Abraham, magicians were able to determine the birth of Christ. However this event put an end to superstition and was the beginning of Christian time.

  5. Intertextual Sexual Politics: Illness and Desire in Enrique Gomez Carrillo's "Del amor", "del dolor y del vicio" and Aurora Caceres's "La rosa muerta"

    ERIC Educational Resources Information Center

    LaGreca, Nancy

    2012-01-01

    This study explores the intertextuality between Aurora Caceres's "La rosa muerta" (1914) and the novel "Del amor, del dolor y del vicio" (1898) by her ex-husband, Enrique Gomez Carrillo. Caceres strategically mentions Gomez Carrillo's novel in "La rosa muerta" to invite a reading of her work in dialogue with his. Both narratives follow the sexual…

  6. Developing market class specific InDel markers from next generation sequence data in Phaseolus vulgaris L.

    PubMed Central

    Moghaddam, Samira Mafi; Song, Qijian; Mamidi, Sujan; Schmutz, Jeremy; Lee, Rian; Cregan, Perry; Osorno, Juan M.; McClean, Phillip E.

    2013-01-01

    Next generation sequence data provides valuable information and tools for genetic and genomic research and offers new insights useful for marker development. This data is useful for the design of accurate and user-friendly molecular tools. Common bean (Phaseolus vulgaris L.) is a diverse crop in which separate domestication events happened in each gene pool followed by race and market class diversification that has resulted in different morphological characteristics in each commercial market class. This has led to essentially independent breeding programs within each market class which in turn has resulted in limited within market class sequence variation. Sequence data from selected genotypes of five bean market classes (pinto, black, navy, and light and dark red kidney) were used to develop InDel-based markers specific to each market class. Design of the InDel markers was conducted through a combination of assembly, alignment and primer design software using 1.6× to 5.1× coverage of Illumina GAII sequence data for each of the selected genotypes. The procedure we developed for primer design is fast, accurate, less error prone, and higher throughput than when they are designed manually. All InDel markers are easy to run and score with no need for PCR optimization. A total of 2687 InDel markers distributed across the genome were developed. To highlight their usefulness, they were employed to construct a phylogenetic tree and a genetic map, showing that InDel markers are reliable, simple, and accurate. PMID:24860578

  7. Developing market class specific InDel markers from next generation sequence data in Phaseolus vulgaris L.

    PubMed

    Moghaddam, Samira Mafi; Song, Qijian; Mamidi, Sujan; Schmutz, Jeremy; Lee, Rian; Cregan, Perry; Osorno, Juan M; McClean, Phillip E

    2014-01-01

    Next generation sequence data provides valuable information and tools for genetic and genomic research and offers new insights useful for marker development. This data is useful for the design of accurate and user-friendly molecular tools. Common bean (Phaseolus vulgaris L.) is a diverse crop in which separate domestication events happened in each gene pool followed by race and market class diversification that has resulted in different morphological characteristics in each commercial market class. This has led to essentially independent breeding programs within each market class which in turn has resulted in limited within market class sequence variation. Sequence data from selected genotypes of five bean market classes (pinto, black, navy, and light and dark red kidney) were used to develop InDel-based markers specific to each market class. Design of the InDel markers was conducted through a combination of assembly, alignment and primer design software using 1.6× to 5.1× coverage of Illumina GAII sequence data for each of the selected genotypes. The procedure we developed for primer design is fast, accurate, less error prone, and higher throughput than when they are designed manually. All InDel markers are easy to run and score with no need for PCR optimization. A total of 2687 InDel markers distributed across the genome were developed. To highlight their usefulness, they were employed to construct a phylogenetic tree and a genetic map, showing that InDel markers are reliable, simple, and accurate.

  8. Estrellas jóvenes en la nube molecular del Camaleón II

    NASA Astrophysics Data System (ADS)

    Chavero, C.; Mazzalay, X.; Paz, D.; Quinzio, B.; Racca, G.; Sales, L.; Stasyszyn, F.; Ahumada, A.; Gómez, M.

    We present optical spectra of three candidate young stellar objects in the Chamaeleon II dark cloud. The observations were carried out at the CASLEO with the REOSC (DS) spectrograph, covering a spectral range between 5000 < λ < 8000 Å. These objects were selected from two lists of candidate young stars proposed by Larson et al. (1998, A&A 337:465) and Voung et al. (2001, A&A 379:208) based on the infrared excesses. We find Hα in emission in two of the three objects. This is an indicator of the pre-main sequence evolutionary state of a star. In addition, for one of the objects with Hα in emission we detect the TiO absorption bands (6180 and 7100 Å), characteristic of the M spectral type. The nature of the third object remains uncertain and higher signal to noise spectra are required to clarify its evolutionary status.

  9. Molecular imaging in atherosclerosis.

    PubMed

    Glaudemans, Andor W J M; Slart, Riemer H J A; Bozzao, Alessandro; Bonanno, Elena; Arca, Marcello; Dierckx, Rudi A J O; Signore, Alberto

    2010-12-01

    Atherosclerosis is the major cause of cardiovascular disease, which still has the leading position in morbidity and mortality in the Western world. Many risk factors and pathobiological processes are acting together in the development of atherosclerosis. This leads to different remodelling stages (positive and negative) which are both associated with plaque physiology and clinical presentation. The different remodelling stages of atherosclerosis are explained with their clinical relevance. Recent advances in basic science have established that atherosclerosis is not only a lipid storage disease, but that also inflammation has a fundamental role in all stages of the disease. The molecular events leading to atherosclerosis will be extensively reviewed and described. Further on in this review different modalities and their role in the different stages of atherosclerosis will be discussed. Non-nuclear invasive imaging techniques (intravascular ultrasound, intravascular MRI, intracoronary angioscopy and intravascular optical coherence tomography) and non-nuclear non-invasive imaging techniques (ultrasound with Doppler flow, electron-bean computed tomography, coronary computed tomography angiography, MRI and coronary artery MR angiography) will be reviewed. After that we focus on nuclear imaging techniques for detecting atherosclerotic plaques, divided into three groups: atherosclerotic lesion components, inflammation and thrombosis. This emerging area of nuclear imaging techniques can provide measures of biological activity of atherosclerotic plaques, thereby improving the prediction of clinical events. As we will see in the future perspectives, at present, there is no special tracer that can be called the diagnostic tool to diagnose prospective stroke or infarction in patients. Nevertheless, we expect such a tracer to be developed in the next few years and maybe, theoretically, it could even be used for targeted therapy (in the form of a beta-emitter) to combat

  10. Nanoparticles for molecular imaging.

    PubMed

    Sheng, Yang; Liao, Lun De; Thakor, Nitish V; Tan, Mei Chee

    2014-10-01

    Imaging techniques have been instrumental in the visualization of fundamental biological processes, identification and diagnosis of diseased states and the development of structure-function relationships at the cellular, tissue and anatomical levels. Together with the advancements made in imaging techniques, complementary chemical compounds, also known as imaging probes or contrast agents, are developed to improve the visibility of the image by enhancing sensitivity, and for the identification and quantitation of specific molecular species or structures. Extensive studies have been conducted to explore the use of inorganic nanoparticles which exhibit magnetic and optical properties unique to the nano regime so as to enhance the signals sensitivity for magnetic resonance and fluorescent imaging. These physical properties are tailored by controlling the size, shape and surface properties of nanoparticles. In addition, surface modification of nanoparticles is often required to improve its stability, compatibility and functionality. Surfactants, surface-active agents, have been used to engineer the surface characteristics of nanoparticles to improved particle stability and functionality. Surfactants enhance nanoparticle stability through the reduction of surface energy, and by acting as a barrier to agglomeration through either steric hindrance or repulsive electrostatic forces. Coupling of nanoparticles with biomolecules such as antibodies or tumor targeting peptides are enabled by the presence of functional groups (e.g., carboxyl or amine groups) on surfactants. This paper provides an overview of the chemistry underlying the synthesis and surface modification of nanomaterials together with a discussion on how the physical properties (e.g., magnetic, absorption and luminescent) can be controlled. The applications of these nanoparticles for magnetic resonance, fluorescent and photoacoustic imaging techniques that do not rely on ionizing radiation are also covered in

  11. HIV Molecular Immunology 2014

    SciTech Connect

    Yusim, Karina; Korber, Bette Tina Marie; Barouch, Dan; Koup, Richard; de Boer, Rob; Moore, John P.; Brander, Christian; Haynes, Barton F.; Walker, Bruce D.

    2015-02-03

    HIV Molecular Immunology is a companion volume to HIV Sequence Compendium. This publication, the 2014 edition, is the PDF version of the web-based HIV Immunology Database (http://www.hiv.lanl.gov/content/immunology/). The web interface for this relational database has many search options, as well as interactive tools to help immunologists design reagents and interpret their results. In the HIV Immunology Database, HIV-specific B-cell and T-cell responses are summarized and annotated. Immunological responses are divided into three parts, CTL, T helper, and antibody. Within these parts, defined epitopes are organized by protein and binding sites within each protein, moving from left to right through the coding regions spanning the HIV genome. We include human responses to natural HIV infections, as well as vaccine studies in a range of animal models and human trials. Responses that are not specifically defined, such as responses to whole proteins or monoclonal antibody responses to discontinuous epitopes, are summarized at the end of each protein section. Studies describing general HIV responses to the virus, but not to any specific protein, are included at the end of each part. The annotation includes information such as crossreactivity, escape mutations, antibody sequence, TCR usage, functional domains that overlap with an epitope, immune response associations with rates of progression and therapy, and how specific epitopes were experimentally defined. Basic information such as HLA specificities for T-cell epitopes, isotypes of monoclonal antibodies, and epitope sequences are included whenever possible. All studies that we can find that incorporate the use of a specific monoclonal antibody are included in the entry for that antibody. A single T-cell epitope can have multiple entries, generally one entry per study. Finally, maps of all defined linear epitopes relative to the HXB2 reference proteins are provided.

  12. Molecular Pharmacology of Phytocannabinoids.

    PubMed

    Turner, Sarah E; Williams, Claire M; Iversen, Leslie; Whalley, Benjamin J

    2017-01-01

    Cannabis sativa has been used for recreational, therapeutic and other uses for thousands of years. The plant contains more than 120 C21 terpenophenolic constituents named phytocannabinoids. The Δ(9)-tetrahydrocannabinol type class of phytocannabinoids comprises the largest proportion of the phytocannabinoid content. Δ(9)-tetrahydrocannabinol was first discovered in 1971. This led to the discovery of the endocannabinoid system in mammals, including the cannabinoid receptors CB1 and CB2. Δ(9)-Tetrahydrocannabinol exerts its well-known psychotropic effects through the CB1 receptor but this effect of Δ(9)-tetrahydrocannabinol has limited the use of cannabis medicinally, despite the therapeutic benefits of this phytocannabinoid. This has driven research into other targets outside the endocannabinoid system and has also driven research into the other non-psychotropic phytocannabinoids present in cannabis. This chapter presents an overview of the molecular pharmacology of the seven most thoroughly investigated phytocannabinoids, namely Δ(9)-tetrahydrocannabinol, Δ(9)-tetrahydrocannabivarin, cannabinol, cannabidiol, cannabidivarin, cannabigerol, and cannabichromene. The targets of these phytocannabinoids are defined both within the endocannabinoid system and beyond. The pharmacological effect of each individual phytocannabinoid is important in the overall therapeutic and recreational effect of cannabis and slight structural differences can elicit diverse and competing physiological effects. The proportion of each phytocannabinoid can be influenced by various factors such as growing conditions and extraction methods. It is therefore important to investigate the pharmacology of these seven phytocannabinoids further, and characterise the large number of other phytocannabinoids in order to better understand their contributions to the therapeutic and recreational effects claimed for the whole cannabis plant and its extracts.

  13. Aceptabilidad del diagnóstico rápido casero para HIV entre hombres gay y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires.

    PubMed

    Balán, Iván C; Carballo-Diéguez, Alex; Marone, Rubén O; Pando, María A; Barreda, Victoria; Avila, María M

    2011-03-01

    El uso del diagnóstico rápido para HIV en Argentina, así como otros países de Latinoamérica, ha sido limitado hasta el momento. Este trabajo reporta los resultados provenientes de un estudio cualitativo realizado entre hombres gays y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires, Argentina. El objetivo principal del mismo fue conocer las ventajas y desventajas que los hombres G&HSH perciben en relación al diagnóstico rápido casero para HIV. Se realizaron ocho grupos focales con 73 participantes en los cuales se discutió acerca de las ventajas y desventajas del uso de los diagnósticos rápidos. Las respuestas fueron codificadas utilizando un programa para análisis de datos cualitativos (NVivo) y analizadas temáticamente. Los participantes describieron numerosas ventajas sobre el uso del diagnóstico rápido casero, aunque algunos reportaron importantes preocupaciones dentro de las cuales se destaca la posibilidad de impulsos suicidas si alguien recibe un resultado positivo estando solo. En términos generales se observó una gran aceptabilidad para el uso del diagnóstico rápido si el mismo es realizado por personal de salud en lugares acondicionados para este fin.

  14. Aceptabilidad del diagnóstico rápido casero para HIV entre hombres gay y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires

    PubMed Central

    Balán, Iván C.; Carballo-Diéguez, Alex; Marone, Rubén O.; Pando, María A.; Barreda, Victoria; Ávila, María M.

    2011-01-01

    Resumen El uso del diagnóstico rápido para HIV en Argentina, así como otros países de Latinoamérica, ha sido limitado hasta el momento. Este trabajo reporta los resultados provenientes de un estudio cualitativo realizado entre hombres gays y otros hombres que tienen sexo con hombres (G&HSH) de la Ciudad de Buenos Aires, Argentina. El objetivo principal del mismo fue conocer las ventajas y desventajas que los hombres G&HSH perciben en relación al diagnóstico rápido casero para HIV. Se realizaron ocho grupos focales con 73 participantes en los cuales se discutió acerca de las ventajas y desventajas del uso de los diagnósticos rápidos. Las respuestas fueron codificadas utilizando un programa para análisis de datos cualitativos (NVivo) y analizadas temáticamente. Los participantes describieron numerosas ventajas sobre el uso del diagnóstico rápido casero, aunque algunos reportaron importantes preocupaciones dentro de las cuales se destaca la posibilidad de impulsos suicidas si alguien recibe un resultado positivo estando solo. En términos generales se observó una gran aceptabilidad para el uso del diagnóstico rápido si el mismo es realizado por personal de salud en lugares acondicionados para este fin. PMID:25284951

  15. Advances in multimodal molecular imaging.

    PubMed

    Auletta, Luigi; Gramanzini, Matteo; Gargiulo, Sara; Albanese, Sandra; Salvatore, Marco; Greco, Adelaide

    2017-03-01

    Preclinical molecular imaging is an emerging field. Improving the ability of scientists to study the molecular basis of human pathology in animals is of the utmost importance for future advances in all fields of human medicine. Moreover, the possibility of developing new imaging techniques or of implementing old ones adapted to the clinic is a significant area. Cardiology, neurology, immunology and oncology have all been studied with preclinical molecular imaging. The functional techniques of photoacoustic imaging (PAI), fluorescence molecular tomography (FMT), positron emission tomography (PET), and single photon emission computed tomography (SPECT) in association with each other or with the anatomic reference provided by computed tomography (CT) as well as with anatomic and functional information provided by magnetic resonance (MR) have all been proficiently applied to animal models of human disease. All the above-mentioned imaging techniques have shown their ability to explore the molecular mechanisms involved in animal models of disease. The clinical translatability of most of the techniques motivates the ongoing study of their possible fields of application. The ability to combine two or more techniques allows obtaining as much information as possible on the molecular processes involved in pathologies, reducing the number of animals necessary in each experiment. Merging molecular probes compatible with various imaging technique will further expand the capability to achieve the best results.

  16. Diffractive molecular-orbital tomography

    NASA Astrophysics Data System (ADS)

    Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang

    2017-03-01

    High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.

  17. Molecular tools for chemical biotechnology

    PubMed Central

    Galanie, Stephanie; Siddiqui, Michael S.; Smolke, Christina D.

    2013-01-01

    Biotechnological production of high value chemical products increasingly involves engineering in vivo multi-enzyme pathways and host metabolism. Recent approaches to these engineering objectives have made use of molecular tools to advance de novo pathway identification, tunable enzyme expression, and rapid pathway construction. Molecular tools also enable optimization of single enzymes and entire genomes through diversity generation and screening, whole cell analytics, and synthetic metabolic control networks. In this review, we focus on advanced molecular tools and their applications to engineered pathways in host organisms, highlighting the degree to which each tool is generalizable. PMID:23528237

  18. EVOLUTIONARY FOUNDATIONS FOR MOLECULAR MEDICINE

    PubMed Central

    Nesse, Randolph M.; Ganten, Detlev; Gregory, T. Ryan; Omenn, Gilbert S.

    2015-01-01

    Evolution has long provided a foundation for population genetics, but many major advances in evolutionary biology from the 20th century are only now being applied in molecular medicine. They include the distinction between proximate and evolutionary explanations, kin selection, evolutionary models for cooperation, and new strategies for tracing phylogenies and identifying signals of selection. Recent advances in genomics are further transforming evolutionary biology and creating yet more opportunities for progress at the interface of evolution with genetics, medicine, and public health. This article reviews 15 evolutionary principles and their applications in molecular medicine in hopes that readers will use them and others to speed the development of evolutionary molecular medicine. PMID:22544168

  19. Photoelectron photoion molecular beam spectroscopy

    SciTech Connect

    Trevor, D.J.

    1980-12-01

    The use of supersonic molecular beams in photoionization mass spectroscopy and photoelectron spectroscopy to assist in the understanding of photoexcitation in the vacuum ultraviolet is described. Rotational relaxation and condensation due to supersonic expansion were shown to offer new possibilities for molecular photoionization studies. Molecular beam photoionization mass spectroscopy has been extended above 21 eV photon energy by the use of Stanford Synchrotron Radiation Laboratory (SSRL) facilities. Design considerations are discussed that have advanced the state-of-the-art in high resolution vuv photoelectron spectroscopy. To extend gas-phase studies to 160 eV photon energy, a windowless vuv-xuv beam line design is proposed.

  20. Molecular Hydrodynamics from Memory Kernels

    NASA Astrophysics Data System (ADS)

    Lesnicki, Dominika; Vuilleumier, Rodolphe; Carof, Antoine; Rotenberg, Benjamin

    2016-04-01

    The memory kernel for a tagged particle in a fluid, computed from molecular dynamics simulations, decays algebraically as t-3 /2 . We show how the hydrodynamic Basset-Boussinesq force naturally emerges from this long-time tail and generalize the concept of hydrodynamic added mass. This mass term is negative in the present case of a molecular solute, which is at odds with incompressible hydrodynamics predictions. Lastly, we discuss the various contributions to the friction, the associated time scales, and the crossover between the molecular and hydrodynamic regimes upon increasing the solute radius.

  1. Thermopower measurements in molecular junctions.

    PubMed

    Rincón-García, Laura; Evangeli, Charalambos; Rubio-Bollinger, Gabino; Agraït, Nicolás

    2016-08-07

    The measurement of thermopower in molecular junctions offers complementary information to conductance measurements and is becoming essential for the understanding of transport processes at the nanoscale. In this review, we discuss the recent advances in the study of the thermoelectric properties of molecular junctions. After presenting the theoretical background for thermoelectricity at the nanoscale, we review the experimental techniques for measuring the thermopower in these systems and discuss the main results. Finally, we consider the challenges in the application of molecular junctions in viable thermoelectric devices.

  2. NASA Applications of Molecular Nanotechnology

    NASA Technical Reports Server (NTRS)

    Globus, Al; Bailey, David; Han, Jie; Jaffe, Richard; Levit, Creon; Merkle, Ralph; Srivastava, Deepak

    1998-01-01

    Laboratories throughout the world are rapidly gaining atomically precise control over matter. As this control extends to an ever wider variety of materials, processes and devices, opportunities for applications relevant to NASA's missions will be created. This document surveys a number of future molecular nanotechnology capabilities of aerospace interest. Computer applications, launch vehicle improvements, and active materials appear to be of particular interest. We also list a number of applications for each of NASA's enterprises. If advanced molecular nanotechnology can be developed, almost all of NASA's endeavors will be radically improved. In particular, a sufficiently advanced molecular nanotechnology can arguably bring large scale space colonization within our grasp.

  3. Interference-based molecular transistors

    PubMed Central

    Li, Ying; Mol, Jan A.; Benjamin, Simon C.; Briggs, G. Andrew D.

    2016-01-01

    Molecular transistors have the potential for switching with lower gate voltages than conventional field-effect transistors. We have calculated the performance of a single-molecule device in which there is interference between electron transport through the highest occupied molecular orbital and the lowest unoccupied molecular orbital of a single molecule. Quantum interference results in a subthreshold slope that is independent of temperature. For realistic parameters the change in gate potential required for a change in source-drain current of two decades is 20 mV, which is a factor of six smaller than the theoretical limit for a metal-oxide-semiconductor field-effect transistor. PMID:27646692

  4. Introduction to Accelerated Molecular Dynamics

    SciTech Connect

    Perez, Danny

    2012-07-10

    Molecular Dynamics is the numerical solution of the equations of motion of a set of atoms, given an interatomic potential V and some boundary and initial conditions. Molecular Dynamics is the largest scale model that gives unbiased dynamics [x(t),p(t)] in full atomistic detail. Molecular Dynamics: is simple; is 'exact' for classical dynamics (with respect to a given V); can be used to compute any (atomistic) thermodynamical or dynamical properties; naturally handles complexity -- the system does the right thing at the right time. The physics derives only from the interatomic potential.

  5. Conformational Transitions in Molecular Systems

    NASA Astrophysics Data System (ADS)

    Bachmann, M.; Janke, W.

    2008-11-01

    Proteins are the "work horses" in biological systems. In almost all functions specific proteins are involved. They control molecular transport processes, stabilize the cell structure, enzymatically catalyze chemical reactions; others act as molecular motors in the complex machinery of molecular synthetization processes. Due to their significance, misfolds and malfunctions of proteins typically entail disastrous diseases, such as Alzheimer's disease and bovine spongiform encephalopathy (BSE). Therefore, the understanding of the trinity of amino acid composition, geometric structure, and biological function is one of the most essential challenges for the natural sciences. Here, we glance at conformational transitions accompanying the structure formation in protein folding processes.

  6. [Molecular diagnosis of melanocytic tumors].

    PubMed

    Bauer, J

    2016-01-01

    Melanoma therapy has undergone a paradigm shift. Classic chemotherapies with poor treatment responses have been replaced by modern immune checkpoint blockades and targeted therapies with excellent responses. The latter require precise diagnosis of mutations in the melanoma genome as molecular targets for the small molecules. The diagnosis of melanomas has also been supplemented by molecular techniques. Differential diagnosis of melanoma and melanoma simulators such as atypical Spitz nevi can be supported by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). Here we review the indications and methods for molecular diagnosis of melanocytic tumors.

  7. Molecularly sensitive optical coherence tomography.

    PubMed

    Bredfeldt, Jeremy S; Vinegoni, Claudio; Marks, Daniel L; Boppart, Stephen A

    2005-03-01

    Molecular contrast in optical coherence tomography (OCT) is demonstrated by use of coherent anti-Stokes Raman scattering (CARS) for molecular sensitivity. Femtosecond laser pulses are focused into a sample by use of a low-numerical-aperture lens to generate CARS photons, and the backreflected CARS signal is interferometrically measured. With the chemical selectivity provided by CARS and the advanced imaging capabilities of OCT, this technique may be useful for molecular contrast imaging in biological tissues. CARS can be generated and interferometrically measured over at least 600 microm of the depth of field of a low-numerical-aperture objective.

  8. Molecularly doped metals.

    PubMed

    Avnir, David

    2014-02-18

    The many millions of organic, inorganic, and bioorganic molecules represent a very rich library of chemical, biological, and physical properties that do not show up among the approximately 100 metals. The ability to imbue metals with any of these molecular properties would open up tremendous potential for the development of new materials. In addition to their traditional features and their traditional applications, metals would have new traits, which would merge their classical virtues such as conductivity and catalytic activity with the diverse properties of these molecules. In this Account, we describe a new materials methodology, which enables, for the first time, the incorporation and entrapment of small organic molecules, polymers, and biomolecules within metals. These new materials are denoted dopant@metal. The creation of dopant@metal yields new properties that are more than or different from the sum of the individual properties of the two components. So far we have developed methods for the doping of silver, copper, gold, iron, palladium, platinum, and some of their alloys, as well as Hg-Ag amalgams. We have successfully altered classical metal properties (such as conductivity), induced unorthodox properties (such as rendering a metal acidic or basic), used metals as heterogeneous matrices for homogeneous catalysts, and formed new metallic catalysts such as metals doped with organometallic complexes. In addition, we have created materials that straddle the border between polymers and metals, we have entrapped enzymes to form bioactive metals, we have induced chirality within metals, we have made corrosion-resistant iron, we formed efficient biocidal materials, and we demonstrated a new concept for batteries. We have developed a variety of methods for synthesizing dopant@metals including aqueous homogeneous and heterogeneous reductions of the metal cations, reductions in DMF, electrochemical entrapments, thermal decompositions of zerovalent metal carbonyls

  9. Exercises in Molecular Computing

    PubMed Central

    2014-01-01

    Conspectus The successes of electronic digital logic have transformed every aspect of human life over the last half-century. The word “computer” now signifies a ubiquitous electronic device, rather than a human occupation. Yet evidently humans, large assemblies of molecules, can compute, and it has been a thrilling challenge to develop smaller, simpler, synthetic assemblies of molecules that can do useful computation. When we say that molecules compute, what we usually mean is that such molecules respond to certain inputs, for example, the presence or absence of other molecules, in a precisely defined but potentially complex fashion. The simplest way for a chemist to think about computing molecules is as sensors that can integrate the presence or absence of multiple analytes into a change in a single reporting property. Here we review several forms of molecular computing developed in our laboratories. When we began our work, combinatorial approaches to using DNA for computing were used to search for solutions to constraint satisfaction problems. We chose to work instead on logic circuits, building bottom-up from units based on catalytic nucleic acids, focusing on DNA secondary structures in the design of individual circuit elements, and reserving the combinatorial opportunities of DNA for the representation of multiple signals propagating in a large circuit. Such circuit design directly corresponds to the intuition about sensors transforming the detection of analytes into reporting properties. While this approach was unusual at the time, it has been adopted since by other groups working on biomolecular computing with different nucleic acid chemistries. We created logic gates by modularly combining deoxyribozymes (DNA-based enzymes cleaving or combining other oligonucleotides), in the role of reporting elements, with stem–loops as input detection elements. For instance, a deoxyribozyme that normally exhibits an oligonucleotide substrate recognition region is

  10. Molecular Simulations in Astrobiology

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael A.; Schweighofer, Karl; Chipot, Christophe; New, Michael H.

    2000-01-01

    One of the main goals of astrobiology is to understand the origin of cellular life. The most direct approach to this problem is to construct laboratory models of protocells. Such efforts, currently underway in the NASA Astrobiology Program, are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures that are capable of performing protocellular functions. Many of these functions, such as importing nutrients, capturing energy and responding to changes in the environment, are carried out by proteins bound to membranes. We use computer simulations to address the following questions about these proteins: (1) How do small proteins self-organize into ordered structures at water-membrane interfaces and insert into membranes? (2) How do peptides form membrane-spanning structures (e.g. channels)? (3) By what mechanisms do such structures perform their functions? The simulations are performed using the molecular dynamics method. In this method, Newton's equations of motion for each atom in the system are solved iteratively. At each time step, the forces exerted on each atom by the remaining atoms are evaluated by dividing them into two parts. Short-range forces are calculated in real space while long-range forces are evaluated in reciprocal space, using a particle-mesh algorithm which is of order O(NInN). With a time step of 2 femtoseconds, problems occurring on multi-nanosecond time scales (10(exp 6)-10(exp 8) time steps) are accessible. To address a broader range of problems, simulations need to be extended by three orders of magnitude, which requires algorithmic improvements and codes scalable to a large number of processors. Work in this direction is in progress. Two series of simulations are discussed. In one series, it is shown that nonpolar peptides, disordered in water, translocate to the nonpolar interior of the membrane and fold into helical structures (see Figure). Once in the membrane, the peptides

  11. Exercises in molecular computing.

    PubMed

    Stojanovic, Milan N; Stefanovic, Darko; Rudchenko, Sergei

    2014-06-17

    CONSPECTUS: The successes of electronic digital logic have transformed every aspect of human life over the last half-century. The word "computer" now signifies a ubiquitous electronic device, rather than a human occupation. Yet evidently humans, large assemblies of molecules, can compute, and it has been a thrilling challenge to develop smaller, simpler, synthetic assemblies of molecules that can do useful computation. When we say that molecules compute, what we usually mean is that such molecules respond to certain inputs, for example, the presence or absence of other molecules, in a precisely defined but potentially complex fashion. The simplest way for a chemist to think about computing molecules is as sensors that can integrate the presence or absence of multiple analytes into a change in a single reporting property. Here we review several forms of molecular computing developed in our laboratories. When we began our work, combinatorial approaches to using DNA for computing were used to search for solutions to constraint satisfaction problems. We chose to work instead on logic circuits, building bottom-up from units based on catalytic nucleic acids, focusing on DNA secondary structures in the design of individual circuit elements, and reserving the combinatorial opportunities of DNA for the representation of multiple signals propagating in a large circuit. Such circuit design directly corresponds to the intuition about sensors transforming the detection of analytes into reporting properties. While this approach was unusual at the time, it has been adopted since by other groups working on biomolecular computing with different nucleic acid chemistries. We created logic gates by modularly combining deoxyribozymes (DNA-based enzymes cleaving or combining other oligonucleotides), in the role of reporting elements, with stem-loops as input detection elements. For instance, a deoxyribozyme that normally exhibits an oligonucleotide substrate recognition region is

  12. Visiting the Gödel universe.

    PubMed

    Grave, Frank; Buser, Michael

    2008-01-01

    Visualization of general relativity illustrates aspects of Einstein's insights into the curved nature of space and time to the expert as well as the layperson. One of the most interesting models which came up with Einstein's theory was developed by Kurt Gödel in 1949. The Gödel universe is a valid solution of Einstein's field equations, making it a possible physical description of our universe. It offers remarkable features like the existence of an optical horizon beyond which time travel is possible. Although we know that our universe is not a Gödel universe, it is interesting to visualize physical aspects of a world model resulting from a theory which is highly confirmed in scientific history. Standard techniques to adopt an egocentric point of view in a relativistic world model have shortcomings with respect to the time needed to render an image as well as difficulties in applying a direct illumination model. In this paper we want to face both issues to reduce the gap between common visualization standards and relativistic visualization. We will introduce two techniques to speed up recalculation of images by means of preprocessing and lookup tables and to increase image quality through a special optimization applicable to the Gödel universe. The first technique allows the physicist to understand the different effects of general relativity faster and better by generating images from existing datasets interactively. By using the intrinsic symmetries of Gödel's spacetime which are expressed by the Killing vector field, we are able to reduce the necessary calculations to simple cases using the second technique. This even makes it feasible to account for a direct illumination model during the rendering process. Although the presented methods are applied to Gödel's universe, they can also be extended to other manifolds, for example light propagation in moving dielectric media. Therefore, other areas of research can benefit from these generic improvements.

  13. [La Junta para Ampliación de Estudios and the development of Spanish psychology].

    PubMed

    Carpintero, Helio; Herrero, Fania

    2007-01-01

    During the last decades of the XIXth century, there was an awakening of consciousness for the need of a Spanish cultural renovation, of which one of the aims was to create and develop a Spanish science, resembling the scientific models already established in more advanced countries. There was a desire of Europeanization. Since it was a global social objective, it was necessary to start from the educator's training. In this climate the Junta para Ampliación de Estudios e Investigaciones Científicas, appeared. The role that the Junta played in Spanish research and in the innovation in the Psychopedagogical field through the first third of the XXth century was extremely important. The Junta's policy of scholarship was one of its most substantial achievements, for it made possible that the country reached in a few decades (1907-1936) the European scientific and psychological level. The relations among Spanish teachers and the Institute J.J. Rousseau is to highlighted, as "Geneva School" was to influence deeply the further development of psychology in Spain.

  14. Radio-Observaciones del OH EN la Coma del Cometa Halley Desde EL Hemisferio Sur

    NASA Astrophysics Data System (ADS)

    Silva, A. M.; Bajaja, E.; Morras, R.; Cersosimo, J. C.; Martin, M. C.; Arnal, E. M.; Poppel, W. G. L.; Colomb, F. R.; Mazzaro, J.; Olalde, J. C.; Boriakoff, V.; Mirabel, I. F.

    1987-05-01

    Se utilizó una antena de 30 metros del Instituto Argentino de Radioastronomía para observaciones diarias Cf ebrero a abril de 1986) de la transición en 1667 MHz ( λ = 18 cm) del OH en la coma del cometa Halley. De las observaciones realizadas se concluye: 1) El número promedio de moléculas de OH en la coma durante 37 días de observación fue de (8.9±3.5)x1034 moléculas, lo que implica una tasa de producción promedio de OH de 1.8x1029 moléculas seg-1 y consecuentemente una pérdida de masa promedio de 17±6 toneladas seg-1 . Este valor está de acuerdo con las mediciones realizadas por las sondas Vega y Giotto. 2) El monitoreo desde el lAR revela la existencia de variaciones bruscas en los flujos de absorción del OH. Estas variaciones son consistentes con los modelos que representan la producción gaseosa a partir de ejecciones y/o desprendimientos discretos de materia congelada del núcleo. 3) Las variaciones en la densidad de flujo son consistentes con las estimaciones de los tiem- pos de vida medios del H2O y del OH en presencia del campo de radiación solar. 4) Se encuentra una correlación entre la intensidad del flujo absorbido y anisotropías en Ia dinamica de la coma.

  15. Manual del McVCO 1999

    USGS Publications Warehouse

    McChesney, P.J.

    1999-01-01

    El McVCO es un generador de frecuencias basado en un microcontrolador que reemplaza al oscilador controlado por voltaje (VCO) utilizado en telemetría analógica de datos sísmicas. Acepta señales de baja potencia desde un sismómetro y produce una señal subportadora modulada en frecuencia adecuada para enlaces telefónicos o vía radio a un lugar remoto de recolección de datos. La frecuencia de la subportadora y la ganancia pueden ser seleccionadas mediante un interruptor. Tiene la opción de poder operar con dos canales para la observación con ganancia alta y baja. El McVCO fue diseñado con el propósito de mejorar la telemetría analógica de las señales dentro de la Pacific Northwest Seismograph Network (PNSN) (Red Sismográfica del Noroeste del Pacífico). Su desarrollo recibió el respaldo del Programa de Geofísica de la Universidad de Washington y del "Volcano Hazards and Earthquake Hazards programs of the United States Geological Survey (USGS) (Programa de Investigaciones de Riesgos Volcánicos y Programa de Investigaciones de Riesgos Sísmicos de los EEUU). Cientos de instrumentos se han construido e instalado. Además de utilizarlo el PNSN, el McVCO es usado por el Observatorio Vulcanológico de Alaska para monitorear los volcanes aleutianos y por el USGS Volcano Disaster Assistance Program (Programa de Ayuda en las Catástrofes Volcánicas del USGS) para responder a crisis volcánicas en otros países. Este manual cubre el funcionamiento del McVCO, es una referencia técnica para aquellos que necesitan saber con más detalle cómo funciona el McVCO, y cubre una serie de temas que requieren un trato explícito o que derivan del despliegue del instrumento.

  16. [Revista de Gastroenterologia del Peru: 25 years].

    PubMed

    Celestino Fernández, Alvaro

    2005-01-01

    In this article is described in a very summarized form the history of the Revista de Gastroenterología del Perú (RGP) that dates from the same origins of the Sociedad de Gastroenterología del Perú, when based in October 30 of 1952 already glimpse the presence of the RGP as the official organ for the publication for studies of doctors of the society or foreign guests. We spent 29 years, and this idea becomes reality; and today the RGP turns to their XXV anniversary. The RGP, to locate itself as the Peruvian medical publication best reputation.

  17. Computer representation of molecular surfaces

    SciTech Connect

    Max, N.L.

    1981-07-06

    This review article surveys recent work on computer representation of molecular surfaces. Several different algorithms are discussed for producing vector or raster drawings of space-filling models formed as the union of spheres. Other smoother surfaces are also considered.

  18. Molecular imaging with engineered physiology

    PubMed Central

    Desai, Mitul; Slusarczyk, Adrian L.; Chapin, Ashley; Barch, Mariya; Jasanoff, Alan

    2016-01-01

    In vivo imaging techniques are powerful tools for evaluating biological systems. Relating image signals to precise molecular phenomena can be challenging, however, due to limitations of the existing optical, magnetic and radioactive imaging probe mechanisms. Here we demonstrate a concept for molecular imaging which bypasses the need for conventional imaging agents by perturbing the endogenous multimodal contrast provided by the vasculature. Variants of the calcitonin gene-related peptide artificially activate vasodilation pathways in rat brain and induce contrast changes that are readily measured by optical and magnetic resonance imaging. CGRP-based agents induce effects at nanomolar concentrations in deep tissue and can be engineered into switchable analyte-dependent forms and genetically encoded reporters suitable for molecular imaging or cell tracking. Such artificially engineered physiological changes, therefore, provide a highly versatile means for sensitive analysis of molecular events in living organisms. PMID:27910951

  19. Computerized molecular modeling of carbohydrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Computerized molecular modleing continues to increase in capability and applicability to carbohydrates. This chapter covers nomenclature and conformational aspects of carbohydrates, perhaps of greater use to carbohydrate-inexperienced computational chemists. Its comments on various methods and studi...

  20. Molecular similarity and property similarity.

    PubMed

    Barbosa, Frédérique; Horvath, Dragos

    2004-01-01

    This paper reviews the main efforts undertaken up to date in order to understand, rationalize and apply the similarity principle (similar compounds=>similar properties) as a computational tool in modern drug discovery. The best suited mathematical expression of this classical working hypothesis of medicinal chemistry needs to be carefully chosen (out of the virtually infinite possible implementations in terms of molecular descriptors and molecular similarity metrics), in order to achieve an optimal validation of the hypothesis that molecules that are neighbors in the Structural Space will also display similar properties. This overview will show why no single "absolute" measure of molecular similarity can be conceived, and why molecular similarity scores should be considered tunable tools that need to be adapted to each problem to solve.

  1. Molecular imaging applications for immunology.

    PubMed

    Hildebrandt, Isabel Junie; Gambhir, Sanjiv Sam

    2004-05-01

    The use of multimodality molecular imaging has recently facilitated the study of molecular and cellular events in living subjects in a noninvasive and repetitive manner to improve the diagnostic capability of traditional assays. The noninvasive imaging modalities utilized for both small animal and human imaging include positron emission tomography (PET), single photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound, and computed tomography (CT). Techniques specific to small-animal imaging include bioluminescent imaging (BIm) and fluorescent imaging (FIm). Molecular imaging permits the study of events within cells, the examination of cell trafficking patterns that relate to inflammatory diseases and metastases, and the ability to rapidly screen new drug treatments for distribution and effectiveness. In this paper, we will review the current field of molecular imaging assays (especially those utilizing PET and BIm modalities) and examine how they might impact animal models and human disease in the field of clinical immunology.

  2. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L.; Naruse, Y.

    1992-03-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows ``inventory by difference`` for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  3. Molecular Sieve Regeneration System (MSRS)

    SciTech Connect

    Nasise, J.E.; Anderson, J.L. ); Naruse, Y. )

    1992-01-01

    A Molecular Sieve Regeneration System (MSRS) was added to the existing Tritium Waste Treatment system (TWT) within the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. The Department of Energy (DOE) no longer allows inventory by difference'' for radioactive wastes that are to be buried. The MSRS was designed and built to comply with this requirement. Within the TWT, water is generated by the catalytic conversion of hydrogen isotopes and removed by molecular sieve trapping prior to release to the environment. Molecular sieve regeneration is required to remove the trapped water and to rejuvenate the beds. The MSRS permits the collection and direct tritium assay of regenerated tritiated water from molecular sieve beds. This paper describes the MSRS in detail and how it is interfaced with the TWT.

  4. Molecular dermatology comes of age.

    PubMed

    Has, Cristina; Sitaru, Cassian

    2013-01-01

    Groundbreaking advances on the molecular and cellular physiological and physiopathological skin processes, including the complete sequencing of the genome of several species and the increased availability of gene-modified organisms, paved the way to firmly establishing molecular approaches and methods in experimental, translational, and clinical dermatology. As a result, newly developed experimental ex vivo assays and animal models prove exquisite tools for addressing fundamental physiological cutaneous processes and pathogenic mechanisms of skin diseases. A plethora of new findings that were generated using these experimental tools serve as a strong basis for intense translational research efforts aiming at developing new, specific, and sensitive diagnostic tests and efficient "personalized" therapies with less side-effects. Consequently, a broad array of molecular diagnostic tests and therapies for a wide spectrum of skin diseases ranging from genodermatoses through skin neoplasms, allergy, inflammatory and autoimmune diseases, are already routinely used in the clinical dermatology practice. This article highlights several major developments in molecular experimental and clinical dermatology.

  5. Biological and biomimetic molecular machines.

    PubMed

    Huang, Tony J; Juluri, Bala K

    2008-02-01

    The evolution of life facilitates the creation of biological molecular machines. In these so-called 'nanomachines,' nature elegantly shows that when precisely organized and assembled, simple molecular mechanical components can link motions efficiently from the nanometer scale to the macroscopic world, and achieve complex functions such as powering skeletal muscles, synthesizing ATP and producing DNA/RNA. Inspired by nature, researchers are creating artifical molecular machines with tailored structures and properties, with the aim of realizing man-made active nanosystems that operate with the same efficiency and complexity as biological nanomachines. It is anticipated that in the not-too-distant future, unique applications of biological and biomimetic molecular machines will emerge in areas such as biochemical instrumentation and nanomedicine.

  6. Apparatus for molecular weight separation

    DOEpatents

    Smith, Richard D.; Liu, Chuanliang

    2001-01-01

    The present invention relates generally to an apparatus and method for separating high molecular weight molecules from low molecular weight molecules. More specifically, the invention relates to the use of microdialysis for removal of the salt (low molecular weight molecules) from a nucleotide sample (high molecular weight molecules) for ESI-MS analysis. The dialysis or separation performance of the present invention is improved by (1) increasing dialysis temperature thereby increasing desalting efficiency and improving spectrum quality; (2) adding piperidine and imidazole to the dialysis buffer solution and reducing charge states and further increasing detection sensitivity for DNA; (3) using low concentrations (0-2.5 mM NH4OAc) of dialysis buffer and shifting the DNA negative ions to higher charge states, producing a nearly 10-fold increase in detection sensitivity and a slightly decreased desalting efficiency, (4) conducting a two-stage separation or (5) any combination of (1), (2), (3) and (4).

  7. Molecular imaging with engineered physiology.

    PubMed

    Desai, Mitul; Slusarczyk, Adrian L; Chapin, Ashley; Barch, Mariya; Jasanoff, Alan

    2016-12-02

    In vivo imaging techniques are powerful tools for evaluating biological systems. Relating image signals to precise molecular phenomena can be challenging, however, due to limitations of the existing optical, magnetic and radioactive imaging probe mechanisms. Here we demonstrate a concept for molecular imaging which bypasses the need for conventional imaging agents by perturbing the endogenous multimodal contrast provided by the vasculature. Variants of the calcitonin gene-related peptide artificially activate vasodilation pathways in rat brain and induce contrast changes that are readily measured by optical and magnetic resonance imaging. CGRP-based agents induce effects at nanomolar concentrations in deep tissue and can be engineered into switchable analyte-dependent forms and genetically encoded reporters suitable for molecular imaging or cell tracking. Such artificially engineered physiological changes, therefore, provide a highly versatile means for sensitive analysis of molecular events in living organisms.

  8. Molecular Biology of Nitrogen Fixation

    ERIC Educational Resources Information Center

    Shanmugam, K. T.; Valentine, Raymond C.

    1975-01-01

    Reports that as a result of our increasing knowledge of the molecular biology of nitrogen fixation it might eventually be possible to increase the biological production of nitrogenous fertilizer from atmospheric nitrogen. (GS)

  9. Molecular Mechanism of Water Evaporation.

    PubMed

    Nagata, Yuki; Usui, Kota; Bonn, Mischa

    2015-12-04

    Evaporation is the process by which water changes from a liquid to a gas or vapor, and is a key step in Earth's water cycle. At the molecular level, evaporation requires breaking at least one very strong intermolecular bond between two water molecules at the interface. Despite the importance of this process the molecular mechanism by which an evaporating water molecule gains sufficient energy to escape from the surface has remained elusive. Here, we show, using molecular dynamics simulations at the water-air interface with polarizable classical force field models, that the high kinetic energy of the evaporated water molecule is enabled by a well-timed making and breaking of hydrogen bonds involving at least three water molecules at the interface, the recoil of which allows one of the molecules to escape. The evaporation of water is thus enabled by concerted, ultrafast hydrogen-bond dynamics of interfacial water, and follows one specific molecular pathway.

  10. Visualization of Molecular Orbitals: Formaldehyde

    ERIC Educational Resources Information Center

    Olcott, Richard J.

    1972-01-01

    Describes a computer program that plots a solid" representation of molecular orbital charge density which can be used to analyze wave functions of molecules. Illustrated with diagrams for formaldehyde. (AL)

  11. Molecular Advancements in Forensic Odontology.

    PubMed

    Babu Rs, A; Rose, D

    2015-05-11

    Forensic odontology explores the field of human identification through dental tissues in cases where there is destruction of body tissues in criminal investigations and mass disasters. Forensic odontology involves dentists participating in legal and criminal issues. Parameters such as age and gender identification are important in identifying the person or persons. Over the last two decades, the molecular aspect of forensic sciences has increased, and these molecular techniques now provide a novel approach to forensic odontology. Molecular advancements in science like DNA analysis has extended the range of forensic dentistry as teeth possess the character of resistance toward physical or chemical aggressions. Teeth provide the abundant space for DNA, and hence teeth represent an excellent source of genomic DNA. The present paper focusses on molecular advancements in the field of forensic odontology.

  12. Microfluidic technology for molecular diagnostics.

    PubMed

    Robinson, Tom; Dittrich, Petra S

    2013-01-01

    Molecular diagnostics have helped to improve the lives of millions of patients worldwide by allowing clinicians to diagnose patients earlier as well as providing better ongoing therapies. Point-of-care (POC) testing can bring these laboratory-based techniques to the patient in a home setting or to remote settings in the developing world. However, despite substantial progress in the field, there still remain many challenges. Progress in molecular diagnostics has benefitted greatly from microfluidic technology. This chapter aims to summarise the more recent advances in microfluidic-based molecular diagnostics. Sections include an introduction to microfluidic technology, the challenges of molecular diagnostics, how microfluidic advances are working to solve these issues, some alternative design approaches, and detection within these systems.

  13. [Molecular monitoring of myeloid leukemia].

    PubMed

    Kiss, Richárd; Király, Attila Péter; Gaál-Weisinger, Júlia; Marosvári, Dóra; Gángó, Péter Ambrus; Demeter, Judit; Bödör, Csaba

    2017-03-08

    The last fifteen years brought a revolution both in treatment and diagnostics of chronic myeloid leukemia. Nowadays, the main method for monitoring of the disease is molecular monitoring with real-time PCR technology which can indicate treatment modification. With the development of the international scale and inter-laboratory standardization the residual tumor mass can be measured accurately and the results are comparable between the different laboratories. By the growing experience in the field of molecular responses we can now accurately predict treatment outcome early on with the so called early molecular response and BCR-ABL1 kinetics, allowing the selection of the best TKI with the treatment-free remission representing real option of the near future. Nevertheless, further advancements can be expected, including the workflow automatization and detection of even deeper molecular responses.

  14. Molecular tools used in agriculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A summary of molecular tools used for research in agriculture were presented. Examples of DNA sequencing, library preparation, use of fingerprinting for pathogens and plant crops, high throughput sequencing, whole-genome amplification, reporter genes, and other methods....

  15. Molecularly imprinted materials: synthesis, properties, applications

    NASA Astrophysics Data System (ADS)

    Lisichkin, Georgii V.; Krutyakov, Yu A.

    2006-10-01

    This review is devoted to the method of molecular imprinting. The physicochemical fundamentals and mechanisms of covalent and non-covalent molecular imprinting aimed at the development of organic polymeric sorbents capable of molecular recognition are considered. Attention is focused on the preparation of molecular imprints on mineral supports. The mechanisms of molecular recognition in adsorption are discussed. Application fields of materials with molecular imprints are briefly surveyed.

  16. Increasing the Endoplasmic Reticulum Pool of the F508del Allele of the Cystic Fibrosis Transmembrane Conductance Regulator Leads to Greater Folding Correction by Small Molecule Therapeutics

    PubMed Central

    Chung, W. Joon; Goeckeler-Fried, Jennifer L.; Havasi, Viktoria; Chiang, Annette; Rowe, Steven M.; Plyler, Zackery E.; Hong, Jeong S.; Mazur, Marina; Piazza, Gary A.; Keeton, Adam B.; White, E. Lucile; Rasmussen, Lynn; Weissman, Allan M.; Denny, R. Aldrin; Brodsky, Jeffrey L.; Sorscher, Eric J.

    2016-01-01

    Small molecules that correct the folding defects and enhance surface localization of the F508del mutation in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) comprise an important therapeutic strategy for cystic fibrosis lung disease. However, compounds that rescue the F508del mutant protein to wild type (WT) levels have not been identified. In this report, we consider obstacles to obtaining robust and therapeutically relevant levels of F508del CFTR. For example, markedly diminished steady state amounts of F508del CFTR compared to WT CFTR are present in recombinant bronchial epithelial cell lines, even when much higher levels of mutant transcript are present. In human primary airway cells, the paucity of Band B F508del is even more pronounced, although F508del and WT mRNA concentrations are comparable. Therefore, to augment levels of “repairable” F508del CFTR and identify small molecules that then correct this pool, we developed compound library screening protocols based on automated protein detection. First, cell-based imaging measurements were used to semi-quantitatively estimate distribution of F508del CFTR by high content analysis of two-dimensional images. We evaluated ~2,000 known bioactive compounds from the NIH Roadmap Molecular Libraries Small Molecule Repository in a pilot screen and identified agents that increase the F508del protein pool. Second, we analyzed ~10,000 compounds representing diverse chemical scaffolds for effects on total CFTR expression using a multi-plate fluorescence protocol and describe compounds that promote F508del maturation. Together, our findings demonstrate proof of principle that agents identified in this fashion can augment the level of endoplasmic reticulum (ER) resident “Band B” F508del CFTR suitable for pharmacologic correction. As further evidence in support of this strategy, PYR-41—a compound that inhibits the E1 ubiquitin activating enzyme—was shown to synergistically enhance F508del rescue by C

  17. Increasing the Endoplasmic Reticulum Pool of the F508del Allele of the Cystic Fibrosis Transmembrane Conductance Regulator Leads to Greater Folding Correction by Small Molecule Therapeutics.

    PubMed

    Chung, W Joon; Goeckeler-Fried, Jennifer L; Havasi, Viktoria; Chiang, Annette; Rowe, Steven M; Plyler, Zackery E; Hong, Jeong S; Mazur, Marina; Piazza, Gary A; Keeton, Adam B; White, E Lucile; Rasmussen, Lynn; Weissman, Allan M; Denny, R Aldrin; Brodsky, Jeffrey L; Sorscher, Eric J

    2016-01-01

    Small molecules that correct the folding defects and enhance surface localization of the F508del mutation in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) comprise an important therapeutic strategy for cystic fibrosis lung disease. However, compounds that rescue the F508del mutant protein to wild type (WT) levels have not been identified. In this report, we consider obstacles to obtaining robust and therapeutically relevant levels of F508del CFTR. For example, markedly diminished steady state amounts of F508del CFTR compared to WT CFTR are present in recombinant bronchial epithelial cell lines, even when much higher levels of mutant transcript are present. In human primary airway cells, the paucity of Band B F508del is even more pronounced, although F508del and WT mRNA concentrations are comparable. Therefore, to augment levels of "repairable" F508del CFTR and identify small molecules that then correct this pool, we developed compound library screening protocols based on automated protein detection. First, cell-based imaging measurements were used to semi-quantitatively estimate distribution of F508del CFTR by high content analysis of two-dimensional images. We evaluated ~2,000 known bioactive compounds from the NIH Roadmap Molecular Libraries Small Molecule Repository in a pilot screen and identified agents that increase the F508del protein pool. Second, we analyzed ~10,000 compounds representing diverse chemical scaffolds for effects on total CFTR expression using a multi-plate fluorescence protocol and describe compounds that promote F508del maturation. Together, our findings demonstrate proof of principle that agents identified in this fashion can augment the level of endoplasmic reticulum (ER) resident "Band B" F508del CFTR suitable for pharmacologic correction. As further evidence in support of this strategy, PYR-41-a compound that inhibits the E1 ubiquitin activating enzyme-was shown to synergistically enhance F508del rescue by C18, a small

  18. Molecular dynamics simulation of pyridine

    NASA Astrophysics Data System (ADS)

    Trumpakaj, Zygmunt; Linde, Bogumił

    2015-04-01

    Molecular Dynamics (MD) simulations are used for the investigation of molecular motions in pyridine in the temperature range 20-480 K under normal pressure. The results obtained are analyzed within the frame of the Mori Zwanzig memory function formalism. An analytical approximation of the first memory function K(t) is applied to predict some dependences on temperature. Experimental results of the Rayleigh scattering of depolarized light from liquid pyridine are used as the main base for the comparison.

  19. Data warehousing in molecular biology.

    PubMed

    Schönbach, C; Kowalski-Saunders, P; Brusic, V

    2000-05-01

    In the business and healthcare sectors data warehousing has provided effective solutions for information usage and knowledge discovery from databases. However, data warehousing applications in the biological research and development (R&D) sector are lagging far behind. The fuzziness and complexity of biological data represent a major challenge in data warehousing for molecular biology. By combining experiences in other domains with our findings from building a model database, we have defined the requirements for data warehousing in molecular biology.

  20. Atomic and Molecular Databases, VAMDC

    NASA Astrophysics Data System (ADS)

    Dubernet, M. L.; Zwölf, C. M.; Moreau, N.; Ba, Y. A.

    2016-10-01

    The VAMDC Consortium is a worldwide consortium which federates Atomic and Molecular databases through an e-science infrastructure and a political organisation. About 90% of the inter-connected databases handle data that are used for the interpretation of spectra and for the modeling of media of many fields of astrophysics. This paper presents how the VAMDC Consortium is organised in order to publish atomic and molecular data for astrophysics.

  1. Molecular basis of lymphokine action

    SciTech Connect

    Webb, D.R. ); Pierce, C.W. ); Cohen, S. )

    1987-01-01

    This book contains over 30 selections. Some of the titles are: Regulation of IL2 and related genes at the mRNA level; Molecular biology of Interleukin-3; Isolation and characterization of mouse and human cDNA clones encoding IL-4 and IgA-Enhancing Factor/Esoinophil CSF (IL-5); Molecular cloning and characterization of the human gene for Interleukin-3 (IL-3); and Soluble immune response suppressor (SIRS) mediated inhibition of cell division.

  2. Molecular Spiders in One Dimension

    PubMed Central

    Antal, Tibor; Krapivsky, P. L.; Mallick, Kirone

    2008-01-01

    Molecular spiders are synthetic bio-molecular systems which have “legs” made of short single-stranded segments of DNA. Spiders move on a surface covered with single-stranded DNA segments complementary to legs. Different mappings are established between various models of spiders and simple exclusion processes. For spiders with simple gait and varying number of legs we compute the diffusion coefficient; when the hopping is biased we also compute their velocity. PMID:19079565

  3. Chopped molecular beam multiplexing system

    NASA Technical Reports Server (NTRS)

    Adams, Billy R. (Inventor)

    1986-01-01

    The integration of a chopped molecular beam mass spectrometer with a time multiplexing system is described. The chopping of the molecular beam is synchronized with the time intervals by a phase detector and a synchronous motor. Arithmetic means are generated for phase shifting the chopper with respect to the multiplexer. A four channel amplifier provides the capacity to independently vary the baseline and amplitude in each channel of the multiplexing system.

  4. Molecular machinery built from DNA

    NASA Astrophysics Data System (ADS)

    Bath, Jonathan; Turberfield, Andrew J.

    2013-03-01

    DNA can be used as both construction material and fuel for molecular motors. Systems of motors and tracks can be constructed and movement of the motor along the track can be directly observed. The path that a taken by a motor as it navigates a network of tracks can be programmed by instructions that are added externally or carried by the motor itself. Such systems might be used as part molecular assembly lines that can be dynamically reconfigured in response to changing demands.

  5. Dynamic molecular graphs: "hopping" structures.

    PubMed

    Cortés-Guzmán, Fernando; Rocha-Rinza, Tomas; Guevara-Vela, José Manuel; Cuevas, Gabriel; Gómez, Rosa María

    2014-05-05

    This work aims to contribute to the discussion about the suitability of bond paths and bond-critical points as indicators of chemical bonding defined within the theoretical framework of the quantum theory of atoms in molecules. For this purpose, we consider the temporal evolution of the molecular structure of [Fe{C(CH2 )3 }(CO)3 ] throughout Born-Oppenheimer molecular dynamics (BOMD), which illustrates the changing behaviour of the molecular graph (MG) of an electronic system. Several MGs with significant lifespans are observed across the BOMD simulations. The bond paths between the trimethylenemethane and the metallic core are uninterruptedly formed and broken. This situation is reminiscent of a "hopping" ligand over the iron atom. The molecular graph wherein the bonding between trimethylenemethane and the iron atom takes place only by means of the tertiary carbon atom has the longest lifespan of all the considered structures, which is consistent with the MG found by X-ray diffraction experiments and quantum chemical calculations. In contrast, the η(4) complex predicted by molecular-orbital theory has an extremely brief lifetime. The lifespan of different molecular structures is related to bond descriptors on the basis of the topology of the electron density such as the ellipticities at the FeCH2 bond-critical points and electron delocalisation indices. This work also proposes the concept of a dynamic molecular graph composed of the different structures found throughout the BOMD trajectories in analogy to a resonance hybrid of Lewis structures. It is our hope that the notion of dynamic molecular graphs will prove useful in the discussion of electronic systems, in particular for those in which analysis on the basis of static structures leads to controversial conclusions.

  6. Molecular Detection of Antimicrobial Resistance

    PubMed Central

    Fluit, Ad C.; Visser, Maarten R.; Schmitz, Franz-Josef

    2001-01-01

    The determination of antimicrobial susceptibility of a clinical isolate, especially with increasing resistance, is often crucial for the optimal antimicrobial therapy of infected patients. Nucleic acid-based assays for the detection of resistance may offer advantages over phenotypic assays. Examples are the detection of the methicillin resistance-encoding mecA gene in staphylococci, rifampin resistance in Mycobacterium tuberculosis, and the spread of resistance determinants across the globe. However, molecular assays for the detection of resistance have a number of limitations. New resistance mechanisms may be missed, and in some cases the number of different genes makes generating an assay too costly to compete with phenotypic assays. In addition, proper quality control for molecular assays poses a problem for many laboratories, and this results in questionable results at best. The development of new molecular techniques, e.g., PCR using molecular beacons and DNA chips, expands the possibilities for monitoring resistance. Although molecular techniques for the detection of antimicrobial resistance clearly are winning a place in routine diagnostics, phenotypic assays are still the method of choice for most resistance determinations. In this review, we describe the applications of molecular techniques for the detection of antimicrobial resistance and the current state of the art. PMID:11585788

  7. Molecular chaperones and photoreceptor function

    PubMed Central

    Kosmaoglou, Maria; Schwarz, Nele; Bett, John S.; Cheetham, Michael E.

    2008-01-01

    Molecular chaperones facilitate and regulate protein conformational change within cells. This encompasses many fundamental cellular processes: including the correct folding of nascent chains; protein transport and translocation; signal transduction and protein quality control. Chaperones are, therefore, important in several forms of human disease, including neurodegeneration. Within the retina, the highly specialized photoreceptor cell presents a fascinating paradigm to investigate the specialization of molecular chaperone function and reveals unique chaperone requirements essential to photoreceptor function. Mutations in several photoreceptor proteins lead to protein misfolding mediated neurodegeneration. The best characterized of these are mutations in the molecular light sensor, rhodopsin, which cause autosomal dominant retinitis pigmentosa. Rhodopsin biogenesis is likely to require chaperones, while rhodopsin misfolding involves molecular chaperones in quality control and the cellular response to protein aggregation. Furthermore, the specialization of components of the chaperone machinery to photoreceptor specific roles has been revealed by the identification of mutations in molecular chaperones that cause inherited retinal dysfunction and degeneration. These chaperones are involved in several important cellular pathways and further illuminate the essential and diverse roles of molecular chaperones. PMID:18490186

  8. Molecular Simulations in Astrobiology

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Wilson, Michael A.; Schweighofer, Karl; Chipot, Christophe; New, Michael H.; Vincenzi, Donald L. (Technical Monitor)

    2001-01-01

    One of the main goals of astrobiology is to understand the origin of cellular life. In the absence of any record of the earliest ancestors of contemporary cells, protocells, the most direct way to test our understanding of their characteristics is to construct laboratory models of protocells. Such efforts, currently underway in the NASA Astrobiology Program, are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures and developing designs of molecules that are capable of performing protocellular functions. Many of these functions, such as importing nutrients, capturing and storing energy, and responding to changes in the environment, are carried out by proteins bound to membranes. We use computer simulations to address the following, questions about these proteins: (1) How do small proteins (peptides) organize themselves into ordered structures at water-membrane interfaces and insert into membranes? (2) How do peptides aggregate to form membrane-spannin(y structures (e.g., channels)? (3) By what mechanisms do such aggregates perform their functions? The simulations are performed using the molecular dynamics (MD) method. In this method, Newton's equations of motion for each atom in the system are solved iteratively. At each time step, the forces exerted on each atom by the remaining atoms are evaluated by dividing them into two parts. Short-range forces are calculated directly in real space while long-range forces are evaluated in reciprocal space, usually using a particle-mesh algorithm which is of order O(NlnN). Currently, a time step of 2 femtoseconds is typically used, thereby making studies of problems occurring on multi-nanosecond time scales (10(exp 6) - 10(exp 8) time steps) accessible. To address a broader range of problems, simulations need to be extended by three orders of magnitude. Such an extension requires both algorithmic improvements and codes scalable to a large number of parallel

  9. Molecular Beam Epitaxy of

    NASA Astrophysics Data System (ADS)

    Hsieh, Kuan Hsiung

    Ga(,0.48)In(,0.52)As recently emerges as a promising material for high speed applications. It also has a direct bandgap with gap energy suitable for optical applications. It is the purpose of this thesis to grow high quality Ga(,0.47)In(,0.53)As, lattice-matched Al(,0.48)In(,0.52)As and heterojunction structures by molecular beam epitaxy technique for applications in the areas of modulation-doped high mobility devices and internal photoemission Schottky diodes for infrared detection. Single crystal Al metal deposition on GaInAs by MBE is also studied for its electrical properties. Mobility enhancement has been demonstrated in modulation-doped structures at low temperatures. Very high mobilities were obtained: 10,900 cm('2)/Vs at room temperature, 55,500 cm('2)/Vs at 77K and 70,200 cm('2)/Vs at 10K with corresponding two-dimensional electron gas densities greater than 1 x 10('12) l/cm('2). The quality of Ga(,0.47)In(,0.53)As and the parallel conduction in this material are the limiting factors in its mobility. A new ohmic contact phenomenon has been observed in the MBE single crystal Al metal on Ga(,0.47)In(,0.53)AS samples. Its contact resistivity is measured to be as small as 1 x 10('-6) (OMEGA)-cm('2). The Fermi-level pinning near the conduction band edge might be caused by the interface defects. A planar doping technique has been employed to enhance the built-in barrier height to a value of about 0.5 eV in the single crystal Al on n-p('+)-n-Ga(,0.47)In(,0.52)As structures. This novel quasi-Schottky diode also shows a forward ideal factor of 1.03. As for optical detectors, four kinds of diodes were made for internal photoemission studies: Au Schottky on Ga(,0.47)In(,0.53)As in the wavelength range of 1.9 (mu)m to 2.5 (mu)m, Au Schottky on Al(,0.48)In(,0.52)As in 1.1 (mu)m to 2.0 (mu)m range, single crystal Al on (Al(,0.8)Ga(,0.2))(,0.48)In(,0.52)As with improved quantum yields and lastly a Ga(,0.47)In(,0.53)As/Al(,0.48)In(,0.52)As heterojunction with a measured

  10. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Marina Del Rey, CA. 80.1118 Section 80.1118 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light...

  11. Hopeful (protein InDel) monsters?

    PubMed

    Tóth-Petróczy, Agnes; Tawfik, Dan S

    2014-06-10

    In this issue of Structure, Arpino and colleagues describe in atomic detail how a protein stomachs a deletion within a helix, an event that rarely occurs in nature or in the lab. Can insertions and deletions (InDels) trigger dramatic structural transitions?

  12. Molecular genetics study of deafness in Brazil: 8-year experience.

    PubMed

    de Oliveira, Camila Andréa; Alexandrino, Fabiana; Christiani, Thalita Vitachi; Steiner, Carlos Eduardo; Cunha, José Luiz Rosemberis; Guerra, Andréa Trevas Maciel; Sartorato, Edi Lúcia

    2007-07-15

    Hereditary hearing loss is a complex disorder that involves a large number of genes. In developed countries, 1 in 1,000 children is born with deafness severe enough to require special education services, and about 60% of the cases of isolated deafness have a genetic origin. Although more than 100 genes for hearing loss are known currently, only a few are routinely tested in the clinical practice. In this study, we present our findings from the molecular diagnostic screening of the GJB2 and GJB3 genes, del(GJB6-D13S1,830) and del(GJB6-D13S1,854) deletions in the GJB6 gene, Q829X mutation in the otoferlin gene (OTOF) and, the A1,555G and A7,445G mutations in the mitochondrial genome over an 8-year period. Mutations analysis in the previously mentioned genes and mutations was performed on 645 unrelated Brazilian patients with hearing loss who fell into two different testing groups. Different mutations in the GJB2 gene were responsible for most of cases studied, but deletions in the GJB6 gene as well as mitochondrial mutations were also found. While most cases of hearing loss in this country are due to environmental factors, the genetic etiology of deafness will increasingly be determined as more genetic tests become available.

  13. Temperature Evolution of Molecular Clouds in the Central Molecular Zone

    NASA Astrophysics Data System (ADS)

    Krieger, Nico; Ott, Jürgen; Walter, Fabian; Kruijssen, J. M. Diederik; Beuther, Henrik

    2017-01-01

    We infer the absolute time dependence of kinematic gas temperature along a proposed orbit of molecular clouds in the Central Molecular Zone (CMZ) of the Galactic Center (GC). Ammonia gas temperature maps are one of the results of the ``Survey of Water and Ammonia in the Galactic Center'' (SWAG, PI: J. Ott); the dynamical model of molecular clouds in the CMZ was taken from Kruijssen et al. (2015). We find that gas temperatures increase as a function of time in both regimes before and after the cloud passes pericenter on its orbit in the GC potential. This is consistent with the recent proposal that pericenter passage triggers gravitational collapse. Other investigated quantities (line width, column density, opacity) show no strong sign of time dependence but are likely dominated by cloud-to-cloud variations.

  14. Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.

    NASA Astrophysics Data System (ADS)

    Muñoz-Caro, Guillermo Manuel

    Las nubes moleculares son regiones de formación de estrellas, con temperaturas cinéticas entre 10-50 K y densidades de 103-106 átomos cm-3. Su materia está formada por gas y polvo interestelar. Estas partículas de polvo están cubiertas por una fina capa de hielo, de unos 0.01 μm, que contiene H2O y a menudo CO, CO2, CH3OH y NH3. El hielo es presumiblemente irradiado por fotones ultravioleta y rayos cósmicos en las zonas poco profundas de las nubes moleculares y las regiones circunestelares. En un sistema de vacío, P ˜ 10-7 mbar, simulamos la deposición de hielo a partir de 10 K y la irradiación ultravioleta por medio de una lámpara de descarga de hidrógeno activada con microondas. La evolución del hielo se observa por medio de un espectrómetro infrarrojo. De este modo es posible determinar la composición del hielo observado en el medio interestelar y predecir la presencia de moléculas aún no detectadas en el espacio, que han sido producto del procesamiento del hielo en nuestros experimentos. También es posible calentar el sistema hasta temperatura ambiente para sublimar el hielo depositado. Cuando el hielo ha sido previamente irradiado, se observa un residuo compuesto por moléculas orgánicas complejas, algunas prebióticas, como varios ácidos carboxílicos, aminas, amidas, ésteres y en menor proporción moléculas heterocíclicas y aminoácidos. Algunas de estas moléculas podrían detectarse en estado gaseoso por medio de observaciones milimétricas y de radio. También podrían estar presentes en el polvo cometario, cuyo análisis químico está planeado por las misiones Stardust y Rosetta. Mientras tanto, nuestro grupo está llevando a cabo el análisis de partículas de polvo interplanetario (IDPs), algunas de las cuales pueden ser de origen cometario. Al igual que ocurre con los productos obtenidos por irradiación del hielo en nuestros experimentos, algunas IDPs son ricas en material orgánico que contiene oxígeno.

  15. Molecular Tracers of Turbulent Shocks in Giant Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Pon, Andy; Johnstone, D. I.; Kaufman, M. J.

    2013-01-01

    Molecular clouds exhibit large linewidths, which are usually interpreted as being due to supersonic turbulence. This turbulence plays a key role in many theories of star formation, as it is believed to help support and fragment molecular clouds. Current numerical MHD simulations show that the turbulent energy of a molecular cloud dissipates on the order of a crossing time, but do not explicitly follow how this energy is released. We have run models of C-type shocks, based on Kaufman & Neufeld (1996), propagating into gas with densities near 1000 cm3 at velocities of a few km/s, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with the dissipation of turbulent energy in shocks within molecular clouds. Combining these shock models and estimates for the rate of turbulent energy dissipation (Basu & Murali 2001), we produce synthetic CO spectra and predict those line emissions that will be observable with current and upcoming observational facilities, such as Herschel, SOFIA, ALMA, and CCAT. We compare our synthetic shock spectra to the photodissociation region (PDR) models of Kaufman et al. (1999) and show that mid-J CO lines (e.g., CO J = 7 to 6) from molecular clouds illuminated by standard interstellar radiation fields are dominated by emission from shocked gas. We also present Herschel observations of these shock tracing lines. References: Basu, S. & Murali, C. 2001, ApJ, 551, 743 Kaufman, M. J. & Neufeld, D. A. 1996, ApJ, 456, 250 Kaufman, M. J., Wolfire, M. G., Hollenbach, D. J., & Luhman, M. L. 1999, ApJ, 527, 795

  16. EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces

    NASA Astrophysics Data System (ADS)

    Weinelt, Martin; von Oppen, Felix

    2012-10-01

    In nature, molecules exploit interaction with their environment to realize complex functionalities on the nanometer length scale. Physical, chemical and/or biological specificity is frequently achieved by the switching of molecules between microscopically different states. Paradigmatic examples are the energy production in proton pumps of bacteria or the signal conversion in human vision, which rely on switching molecules between different configurations or conformations by external stimuli. The remarkable reproducibility and unparalleled fatigue resistance of these natural processes makes it highly desirable to emulate nature and develop artificial systems with molecular functionalities. A promising avenue towards this goal is to anchor the molecular switches at surfaces, offering new pathways to control their functional properties, to apply electrical contacts, or to integrate switches into larger systems. Anchoring at surfaces allows one to access the full range from individual molecular switches to self-assembled monolayers of well-defined geometry and to customize the coupling between molecules and substrate or between adsorbed molecules. Progress in this field requires both synthesis and preparation of appropriate molecular systems and control over suitable external stimuli, such as light, heat, or electrical currents. To optimize switching and generate function, it is essential to unravel the geometric structure, the electronic properties and the dynamic interactions of the molecular switches on surfaces. This special section, Molecular Switches at Surfaces, collects 17 contributions describing different aspects of this research field. They analyze elementary processes, both in single molecules and in ensembles of molecules, which involve molecular switching and concomitant changes of optical, electronic, or magnetic properties. Two topical reviews summarize the current status, including both challenges and achievements in the field of molecular switches on

  17. Molecular modeling of inelastic electron transport in molecular junctions

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Kula, Mathias; Luo, Yi

    2008-09-01

    A quantum chemical approach for the modeling of inelastic electron tunneling spectroscopy of molecular junctions based on scattering theory is presented. Within a harmonic approximation, the proposed method allows us to calculate the electron-vibration coupling strength analytically, which makes it applicable to many different systems. The calculated inelastic electron transport spectra are often in very good agreement with their experimental counterparts, allowing the revelation of detailed information about molecular conformations inside the junction, molecule-metal contact structures, and intermolecular interaction that is largely inaccessible experimentally.

  18. Molecular outflows in the Monoceros OB1 molecular cloud

    NASA Technical Reports Server (NTRS)

    Margulis, Michael; Lada, Charles J.; Snell, Ronald L.

    1988-01-01

    Observations of J = 1-0 emission from CO in nine suspected molecular outflows in the Monoceros OB1 molecular cloud are presented. It is found that, if the five sources which are confirmed to be outflows conserve momentum as they evolve, they will sweep up at least 0.6 percent of the mass of the entire cloud before coming into pressure equilibrium with the ambient gas. This number indicates that it should take at most 160 episodes of similar outflow activity in order to sweep up the bulk of the Mon OB1 cloud to highly supersonic speeds.

  19. Organic-based molecular switches for molecular electronics.

    PubMed

    Fuentes, Noelia; Martín-Lasanta, Ana; Alvarez de Cienfuegos, Luis; Ribagorda, Maria; Parra, Andres; Cuerva, Juan M

    2011-10-05

    In a general sense, molecular electronics (ME) is the branch of nanotechnology which studies the application of molecular building blocks for the fabrication of electronic components. Among the different types of molecules, organic compounds have been revealed as promising candidates for ME, due to the easy access, great structural diversity and suitable electronic and mechanical properties. Thanks to these useful capabilities, organic molecules have been used to emulate electronic devices at the nanoscopic scale. In this feature article, we present the diverse strategies used to develop organic switches towards ME with special attention to non-volatile systems.

  20. Molecular diagnostics: Molecular Med Tri-Con 2013.

    PubMed

    Klein, Roger D

    2013-07-01

    The 20th annual Molecular Med Tri-Con conference, sponsored by Cambridge Health Institute (MA, USA), consisted of over 250 presentations within five parallel 'channels': 'Diagnostics, Therapeutics, Clinical, Informatics and Cancer', along with five preliminary symposia, 15 short courses, a plenary keynote session entitled 'Personalized Oncology - Fulfilling the Promise for Today's Patients' and a keynote panel entitled, 'Emerging Technologies and Industry Perspectives'. Over 3000 individuals from academia, clinical laboratories and industry were in attendance. This article will focus on the Keynote Session of 'Molecular Diagnostics' track within the Diagnostics Channel.

  1. Identificación de los miembros del cúmulo NGC 2516

    NASA Astrophysics Data System (ADS)

    de Elía, G. C.; Orellana, R. B.

    El cúmulo abierto NGC 2516 (α = 7h 58m y δ = -60o 45') tiene una edad de, aproximadamente, 150 Myr. El análisis de este sistema es particularmente importante en el Hemisferio Sur debido a su abundancia de estrellas peculiares y muy estudiado aplicando técnicas fotométricas, pero muy poco analizado desde el punto de vista astrométrico. A partir de una placa obtenida en el Observatorio Astronómico de La Plata y observaciones más actuales, nos hemos abocado al estudio de los movimientos propios de este cúmulo con el fin de determinar la pertenencia al mismo de las estrellas del campo de dicho cúmulo. Luego de llevar a cabo la determinación de los movimientos propios de todas las estrellas a partir de las posiciones obtenidas de la placa existente en el Observatorio de La Plata de 1914 y leídas con la MAMA en París, las observaciones realizadas con el círculo meridiano de San Fernando que se encuentra en el Observatorio Félix Aguilar de San Juan y las posiciones existentes en los catálogos AC 2000, Tycho, USNO y UCAC, programamos el método de Vasilevsky y Sanders para determinar la pertenencia de las estrellas de la región al cúmulo en cuestión. En un paso posterior, se realizó una modificación al método anterior para la determinación de los miembros. En esta modificación se consideró la densidad de las estrellas del cúmulo y la densidad de estrellas de campo. Esto permitió evaluar la pertenencia, no sólo a partir del movimiento propio de las estrellas, sino también a partir de la posición de las mismas con respecto al centro del cúmulo. También se consideró la dependencia de los parámetros con la magnitud. Los resultados así obtenidos fueron comparados con otras investigaciones de movimientos propios de la región del cúmulo. El movimiento propio absoluto del cúmulo fue comparado con el obtenido a partir de los catálogos estelares. Se encontró que los resultados coincidían para estrellas brillantes (magnitud más brillante que

  2. Contribuciones tecnicas para la medida de la contaminacion electromagnetica de microondas. Estudio en diversas poblaciones

    NASA Astrophysics Data System (ADS)

    Segura Garcia, Jaume

    La contaminacion ambiental por campos electromagneticos ha resultado ser en estos ultimos anos uno de los problemas mas acuciantes del panorama tecnologico y de salud publica. En el primero de los casos porque las inversiones realizadas son enormes y en el segundo porque cada vez es mayor el numero de articulos, "technical reports" e informes medicos que afirman la existencia de una cierta causalidad, aunque sea debil, entre los campos electromagneticos y ciertos cuadros sintomatologicos. En nuestro caso, hemos dedicado bastantes esfuerzos a investigar el llamado "sindrome de radiofrecuencia / microondas", denominado asi en la literatura cientifica por presentarse en operarios de estaciones de radar y en trabajadores de potentes emisoras de radio y television. En esta memoria presentamos un resumen del trabajo realizado durante los ultimos anos en la medida de la contaminacion electromagnetica ambiental asociado a las comunicaciones inalambricas. En ella se recogen los fundamentos fisicos y propiedades de las ondas electromagneticas, la tecnologia empleada en los sistemas de telefonia celular y los antecedentes relativos a la investigacion de la interaccion de las ondas electromagneticas con organismos vivos. Se desarrolla un procedimiento de medida que ha conducido a la elaboracion de los primeros "mapas de radiofrecuencia" similares, en el aspecto descriptivo, a los mapas de ruido desarrollados en el area de la contaminacion acustica. Por ultimo, se analiza la respuesta subjetiva de los residentes, personas que viven en el entorno de cobertura de las estaciones base de telefonia movil y que se ven sometidos a determinados niveles de radiacion electromagnetica, con el fin de situar este fenomeno al nivel que le corresponde en el ambito de la respuesta subjetiva ciudadana.

  3. Molecular imprinting: perspectives and applications.

    PubMed

    Chen, Lingxin; Wang, Xiaoyan; Lu, Wenhui; Wu, Xiaqing; Li, Jinhua

    2016-04-21

    Molecular imprinting technology (MIT), often described as a method of making a molecular lock to match a molecular key, is a technique for the creation of molecularly imprinted polymers (MIPs) with tailor-made binding sites complementary to the template molecules in shape, size and functional groups. Owing to their unique features of structure predictability, recognition specificity and application universality, MIPs have found a wide range of applications in various fields. Herein, we propose to comprehensively review the recent advances in molecular imprinting including versatile perspectives and applications, concerning novel preparation technologies and strategies of MIT, and highlight the applications of MIPs. The fundamentals of MIPs involving essential elements, preparation procedures and characterization methods are briefly outlined. Smart MIT for MIPs is especially highlighted including ingenious MIT (surface imprinting, nanoimprinting, etc.), special strategies of MIT (dummy imprinting, segment imprinting, etc.) and stimuli-responsive MIT (single/dual/multi-responsive technology). By virtue of smart MIT, new formatted MIPs gain popularity for versatile applications, including sample pretreatment/chromatographic separation (solid phase extraction, monolithic column chromatography, etc.) and chemical/biological sensing (electrochemical sensing, fluorescence sensing, etc.). Finally, we propose the remaining challenges and future perspectives to accelerate the development of MIT, and to utilize it for further developing versatile MIPs with a wide range of applications (650 references).

  4. Fabrication and Characterization of Molecular Electronic Devices.

    PubMed

    Kim, Youngsang; Song, Hyunwook

    2015-02-01

    The concept of molecular electronic devices is utilizing single molecules or molecular monolayers as active electronic components. Rapid advances in technology have enabled us to engineer molecular electronic devices with diverse functionalities. This review article emphasizes on experimental aspects of electronic devices made with single molecules or molecular monolayers, with a primary focus on the characterization and manipulation of charge transport.

  5. [Pertussis in Mexico, an epidemiological overview. A study of 19 years at the Instituto Mexicano del Seguro Social].

    PubMed

    Pérez-Pérez, Gabriela Fidela; Rojas-Mendoza, Teresita; Cabrera-Gaytán, David Alejandro; Grajales-Muñiz, Concepción

    2015-01-01

    Introducción: La infección por Bordetella pertussis ha sido un problema de salud pública en varios países desarrollados y en vías de desarrollo. El objetivo de este estudio fue describir el panorama epidemiológico de los casos de síndrome coqueluchoide y tos ferina del subsistema especial de vigilancia epidemiológica de 1992 a 2011en una población con seguridad social. Métodos: Se obtuvieron los casos del subsistema especial de vigilancia epidemiológica de tos ferina de 1992 a 2011. Se hizo análisis univariado de tasas, razones y proporciones. Se determinó prueba de Wilson para proporciones a un valor alfa del 0.05, t de Student para diferencia de medias. Resultados: Se aprecian ciclos epidémicos, cada tres a cinco años, la incidencia basal promedio, sin contar los años epidémicos, se considera de 0.1 casos confirmados por cada 100 000 derechohabientes adscritos a medicina familiar, la mayor incidencia se registró en 1997 y 2009. Los más afectados han sido los menores de 1 año de edad y en brotes, la enfermedad se presentó en edades mayores. Conclusión: Durante el periodo se observan ciclos epidémicos intermedios de 5 y 3 años, la presentación de la edad es consistente en otros países.

  6. Combinación de Valores de Longitud del Día (LOD) según ventanas de frecuencia

    NASA Astrophysics Data System (ADS)

    Fernández, L. I.; Arias, E. F.; Gambis, D.

    El concepto de solución combinada se sustenta en el hecho de que las diferentes series temporales de datos derivadas a partir de distintas técnicas de la Geodesia Espacial son muy disimiles entre si. Las principales diferencias, fácilmente detectables, entre las distintas series son: diferente intervalo de muestreo, extensión temporal y calidad. Los datos cubren un período reciente de 27 meses (julio 96-oct. 98). Se utilizaron estimaciones de la longitud del día (LOD) originadas en 10 centros operativos del IERS (International Earth Rotation Service) a partir de las técnicas GPS (Global Positioning System) y SLR (Satellite Laser Ranging). La serie temporal combinada así obtenida se comparó con la solución EOP (Parámetros de la Orientación Terrestre) combinada multi-técnica derivada por el IERS (C04). El comportamiento del ruido en LOD para todas las técnicas mostró ser dependiente de la frecuencia (Vondrak, 1998). Por esto, las series dato se dividieron en ventanas de frecuencia, luego de haberles removido bies y tendencias. Luego, se asignaron diferentes factores de peso a cada ventana discriminando por técnicas. Finalmente estas soluciones parcialmente combinadas se mezclaron para obtener la solución combinada final. Sabemos que la mejor solución combinada tendrá una precisión menor que la precisión de las series temporales de datos que la originaron. Aun así, la importancia de una serie combinada confiable de EOP, esto es, de una precisión aceptable y libre de sistematismos evidentes, radica en la necesidad de una base de datos EOP de referencia para el estudio de fenómenos geofísicos que motivan variaciones en la rotación terrestre.

  7. Molecular biomimetics: nanotechnology through biology

    NASA Astrophysics Data System (ADS)

    Sarikaya, Mehmet; Tamerler, Candan; Jen, Alex K.-Y.; Schulten, Klaus; Baneyx, François

    2003-09-01

    Proteins, through their unique and specific interactions with other macromolecules and inorganics, control structures and functions of all biological hard and soft tissues in organisms. Molecular biomimetics is an emerging field in which hybrid technologies are developed by using the tools of molecular biology and nanotechnology. Taking lessons from biology, polypeptides can now be genetically engineered to specifically bind to selected inorganic compounds for applications in nano- and biotechnology. This review discusses combinatorial biological protocols, that is, bacterial cell surface and phage-display technologies, in the selection of short sequences that have affinity to (noble) metals, semiconducting oxides and other technological compounds. These genetically engineered proteins for inorganics (GEPIs) can be used in the assembly of functional nanostructures. Based on the three fundamental principles of molecular recognition, self-assembly and DNA manipulation, we highlight successful uses of GEPI in nanotechnology.

  8. Molecular separation method and apparatus

    DOEpatents

    Villa-Aleman, E.

    1996-04-09

    A method and apparatus are disclosed for separating a gaseous mixture of chemically identical but physically different molecules based on their polarities. The gaseous mixture of molecules is introduced in discrete quantities into the proximal end of a porous glass molecular sieve. The molecular sieve is exposed to microwaves to excite the molecules to a higher energy state from a lower energy state, those having a higher dipole moment being excited more than those with a lower energy state. The temperature of the sieve kept cold by a flow of liquid nitrogen through a cooling jacket so that the heat generated by the molecules colliding with the material is transferred away from the material. The molecules thus alternate between a higher energy state and a lower one, with the portion of molecules having the higher dipole moment favored over the others. The former portion can then be extracted separately from the distal end of the molecular sieve. 2 figs.

  9. Molecular separation method and apparatus

    DOEpatents

    Villa-Aleman, Eliel

    1996-01-01

    A method and apparatus for separating a gaseous mixture of chemically identical but physically different molecules based on their polarities. The gaseous mixture of molecules is introduced in discrete quantities into the proximal end of a porous glass molecular. The molecular sieve is exposed to microwaves to excite the molecules to a higher energy state from a lower energy state, those having a higher dipole moment being excited more than those with a lower energy state. The temperature of the sieve kept cold by a flow of liquid nitrogen through a cooling jacket so that the heat generated by the molecules colliding with the material is transferred away from the material. The molecules thus alternate between a higher energy state and a lower one, with the portion of molecules having the higher dipole moment favored over the others. The former portion can then be extracted separately from the distal end of the molecular sieve.

  10. Molecular Modeling of Thermosetting Polymers

    NASA Astrophysics Data System (ADS)

    Patnaik, Soumya; Varshney, Vikas; Farmer, Barry

    2008-03-01

    In this work we present molecular modeling of thermosetting polymers with special emphasis on building atomistic models. Different approaches to building highly cross-linked polymer networks starting from un-crosslinked systems are discussed. A multi-step procedure for relaxing the molecular topology during crosslinking was proposed which allows for minimizing the increase in the residual internal stresses with increasing degree of crosslinking. This methodology was applied to epoxy based thermosets and several materials properties such as density, Young's modulus, glass transition temperature, thermal expansion coefficient and volume shrinkage during curing were calculated and found to be in good agreement with experimental results. Along with the materials properties, the simulations also highlighted the distribution of molecular weight build up and inception of gel point during the network formation.

  11. Molecular Pathogenesis of Hepatocellular Carcinoma

    PubMed Central

    Ho, Daniel Wai-Hung; Lo, Regina Cheuk-Lam; Chan, Lo-Kong; Ng, Irene Oi-Lin

    2016-01-01

    The pathogenesis of hepatocellular carcinoma (HCC) is a multistep process involving the progressive accumulation of molecular alterations pinpointing different molecular and cellular events. The next-generation sequencing technology is facilitating the global and systematic evaluation of molecular landscapes in HCC. There is emerging evidence supporting the importance of cancer metabolism and tumor microenvironment in providing a favorable and supportive niche to expedite HCC development. Moreover, recent studies have identified distinct surface markers of cancer stem cell (CSC) in HCC, and they also put forward the profound involvement of altered signaling pathways and epigenetic modifications in CSCs, in addition to the concomitant drug resistance and metastasis. Taken together, multiple key genetic and non-genetic factors, as well as liver CSCs, result in the development and progression of HCC. PMID:27781201

  12. Energy Ordering of Molecular Orbitals

    PubMed Central

    2016-01-01

    Orbitals are invaluable in providing a model of bonding in molecules or between molecules and surfaces. Most present-day methods in computational chemistry begin by calculating the molecular orbitals of the system. To what extent have these mathematical objects analogues in the real world? To shed light on this intriguing question, we employ a photoemission tomography study on monolayers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) grown on three Ag surfaces. The characteristic photoelectron angular distribution enables us to assign individual molecular orbitals to the emission features. When comparing the resulting energy positions to density functional calculations, we observe deviations in the energy ordering. By performing complete active space calculations (CASSCF), we can explain the experimentally observed orbital ordering, suggesting the importance of static electron correlation beyond a (semi)local approximation. On the other hand, our results also show reality and robustness of the orbital concept, thereby making molecular orbitals accessible to experimental observations. PMID:27935313

  13. Physical conditions in molecular clouds

    NASA Technical Reports Server (NTRS)

    Evans, Neal J., II

    1989-01-01

    Recent developments have complicated the picture of the physical conditions in molecular clouds. The discoveries of widespread emission from high-J lines of CD and 12-micron IRAS emission have revealed the presence of considerably hotter gas and dust near the surfaces of molecular clouds. These components can complicate interpretation of the bulk of the cloud gas. Commonly assumed relations between column density or mean density and cloud size are called into question by conflicting results and by consideration of selection effects. Analysis of density and density structure through molecular excitation has shown that very high densities exist in star formation regions, but unresolved structure and possible chemical effects complicate the interpretation. High resolution far-IR and submillimeter observations offer a complementary approach and are beginning to test theoretical predictions of density gradients in clouds.

  14. Molecular imaging in cancer treatment

    PubMed Central

    Michalski, Mark H.

    2010-01-01

    The success of cancer therapy can be difficult to predict, as its efficacy is often predicated upon characteristics of the cancer, treatment, and individual that are not fully understood or are difficult to ascertain. Monitoring the response of disease to treatment is therefore essential and has traditionally been characterized by changes in tumor volume. However, in many instances, this singular measure is insufficient for predicting treatment effects on patient survival. Molecular imaging allows repeated in vivo measurement of many critical molecular features of neoplasm, such as metabolism, proliferation, angiogenesis, hypoxia, and apoptosis, which can be employed for monitoring therapeutic response. In this review, we examine the current methods for evaluating response to treatment and provide an overview of emerging PET molecular imaging methods that will help guide future cancer therapies. PMID:20661557

  15. [Molecular targets in colon cancer].

    PubMed

    Borner, M M

    2006-04-01

    Colorectal cancer is the second leading cause of cancer death in Switzerland. The nihilism that dominated the treatment of these patients for decades has been replaced by a measure of enthusiasm, given recent therapeutic advances. New anticancer drugs such as irinotecan and oxaliplatin have changed the standard chemotherapy treatment of metastatic colorectal cancer. However, the real hype has come from molecular targeted therapy. Identification of cellular processes characteristic of colon cancer has permitted therapeutic targeting with favorable therapeutic index. Inhibition of the epidermal growth factor receptor in the clinic has provided proof of principle that interruption of signal transduction cascades in patients has therapeutic potential. Angiogenesis, especially the vascular endothelial growth factor pathway, has been proven to be another highly successful molecular target. In this article, we will review molecular targets, which are under active clinical investigation in colon cancer.

  16. Molecular diagnostics of neurodegenerative disorders.

    PubMed

    Agrawal, Megha; Biswas, Abhijit

    2015-01-01

    Molecular diagnostics provide a powerful method to detect and diagnose various neurological diseases such as Alzheimer's and Parkinson's disease. The confirmation of such diagnosis allows early detection and subsequent medical counseling that help specific patients to undergo clinically important drug trials. This provides a medical pathway to have better insight of neurogenesis and eventual cure of the neurodegenerative diseases. In this short review, we present recent advances in molecular diagnostics especially biomarkers and imaging spectroscopy for neurological diseases. We describe advances made in Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD), and finally present a perspective on the future directions to provide a framework for further developments and refinements of molecular diagnostics to combat neurodegenerative disorders.

  17. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  18. Molecular biology of nuclear autoantigens.

    PubMed

    Saitta, M R; Keene, J D

    1992-05-01

    This article provides a historical overview of the application of molecular and immunologic techniques to the analysis of autoantigenic structure and function, as well as to autoantibody recognition of protein and nucleic acid autoantigens. Examples presented here illustrate the role of autoantibodies as tools in the elucidation of the autoimmune components of cellular ribonucleoproteins. In turn, the subsequent molecular dissection of autoantigenic ribonucleoproteins has advanced understanding of autoantibody specificities. The nature of autoantibodies reactive with various proteins and nucleic acids will be the subject of the following articles in this issue. Taken together, these studies of antibody-antigen interactions that arise during the autoimmune response have revealed novel mechanisms of molecular recognition within the RNP autoantigens. These findings are of general importance for understanding basic cellular processes and have contributed to our knowledge of the underlying mechanisms of immunoregulatory abnormalities that arise in autoimmune diseases.

  19. Molecular morphology of cyanobacterial phycobilisomes

    SciTech Connect

    Siegelman, H.W.; Kycia, J.H.

    1982-09-01

    Phycobilisomes were isolated from several cyanobacteria following cell lysis with Triton X-100. They were purified by phosphate precipitation and hydrophobic-interaction chromatography. Their phycobiliprotein compositions were quantitatively determined by application of sets of simultaneous absorbance equations to gel chromatographic separations of the chromoproteins. Phycobilisomes purified from several cyanobacteria had characteristic elution times on agarose gel chromatography. Combining electron microscope observations of phycobilisome structure, phycobiliprotein composition, and agarose gel chromatography estimates of molecular weight permitted the calculation of many details of phycobilisome molecular structure. Complementary chromatic adaptation resulted in a change of phycobilisome composition and structure. The polypeptide compositions of phycobilisomes were examined by sodium dodecyl sulfate-agarose gel chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The phycobilisomes were composed of phycobilipeptides derived from the constituent phycobiliproteins. Higher molecular-weight phycobilipeptide aggregates were also observed. The dominant forces responsible for the maintenance of phycobilisome structure are concluded to be hydropohobic interactions.

  20. Molecular Analysis of Cystic Fibrosis Patients in Hungary – An Update to the Mutational Spectrum

    PubMed Central

    Ivády, Gergely; Koczok, Katalin; Madar, Laszlo; Gombos, Eva; Toth, Izabella; Gyori, Klaudia; Balogh, István

    2015-01-01

    Summary Background In this study the authors present an update to the CFTR mutation profile in Hungary, utilizing data from a selected cohort of 45 cystic fibrosis (CF) patients from different regions of the country. Methods Depending on the preceding analysis, four different mutation detection methods were used. A commercial assay targeting the most common CF-causing mutations was performed as the first test followed by an allele specific PCR for CFTRdele2,3(21kb), Sanger sequencing and MLPA analysis of the coding region of the CFTR gene. Results In our recent study 27 different mutations were detected, including 2 novel ones (c.1037_1038insA and c.1394C>T). Besides F508del (c.1521_1523delCTT), the following mutations were found at a frequency of ≥ 4.0%: W1282X (c.3846G>A), N1303K (c.3909C>G), CFTRdele2,3(21kb) (c.54-5940_273+10250del21kb) and 2184insA (c.2052_2053insA). In addition, four mutations (G542X, Y1092X, 621+1G>T, and 2143delT) were found in more than one allele. Conclusions The updated database of Hungarian mutations not only enables to increase the efficiency of the existing diagnostic approach, but also provides a further refined basis for the introduction of the molecular newborn screening (NBS) program in Hungary.

  1. Molecular modeling of heterogeneous catalysis

    NASA Astrophysics Data System (ADS)

    Gislason, Jason Joseph

    A novel method for modeling heterogeneous catalysis was developed to further facilitate the understanding of catalytic reactor mechanisms. The method employs molecular dynamics simulations, statistical mechanical, and Unity Bond Index - Quadratic Exponential Potential (UBI-QEP) calculations to calculate the rate constants for reactions on metal surfaces. The primary difficulty of molecular dynamics simulations on metal surfaces has been the lack of reliable reactive potential energy surfaces. We have overcome this through the development of the Normalized Bond Index - Reactive Potential Function (NBI-RPF), which can accurately describe the reaction of adsorbates on metal surfaces. The first calculations of rate constants for a reaction on a metal surface using molecular dynamics simulations are presented. This method is applied to the determination of the mechanism for selective hydrogenation of acetylene in an ethylene rich flow. It was determined that the selectivity for acetylene hydrogenation is attributable to the higher reactivity of acetylene versus ethylene with respect to hydrogenation by molecular hydrogen. It was shown that hydrogen transfer from the carbonaceous layer to acetylene or ethylene is insignificant in the hydrogenation process. Molecular dynamics simulations and molecular mechanics calculations were used to determine the diffusion rate constants for dimethylnaphthalene isomers is mordenite. 2,6-dimethylnaphthalene and 2,7-dimethylnaphthalene were found to have similar diffusion rate constants. Grand canonical Monte Carlo calculations were performed on the competitive adsorption of 2,6-dimethylnaphthalene and 2,7-dimethylnaphthalene in type X zeolites exchanged individually with barium, calcium, potassium, and rubidium ions, calcium exchanged MCM-22, and hydrogen form mordenite (MOR), X zeolite, Y zeolite, hypBEB, ZSM- 12, and MCM-22. These calculations showed that barium exchanged X zeolite was the most selective toward 2

  2. Molecular Endotyping of Pulmonary Fibrosis.

    PubMed

    Goodwin, Amanda T; Jenkins, Gisli

    2016-01-01

    Idiopathic pulmonary fibrosis (IPF) is a devastating and incurable progressive fibrotic lung condition associated with a significant disease burden. In recent years there has been an exponential increase in the number of preclinical and clinical studies performed in IPF. IPF is defined according to rigid diagnostic criteria; hence, a significant subset of patients with unclassifiable disease has been excluded from these studies. The traditional diagnostic classification of all progressive fibrotic lung diseases uses specific clinical, radiological, and histopathological features to define each condition. However, the considerable heterogeneity within each form of pulmonary fibrosis has raised the possibility of distinct pathophysiological mechanisms culminating in a common phenotype. Thus, the classification of fibrotic lung diseases according to the driving molecular mechanisms rather than specific user-defined histopathological and radiological features could improve several aspects of clinical care. Discoveries from basic science research have defined multiple complex molecular pathways involved in the pathogenesis of pulmonary fibrosis that may provide markers for the molecular endotyping of this disease. In addition, these molecular pathways have revealed potential therapeutic targets. Reclassifying progressive fibrotic lung diseases according to molecular endotypes may allow for more accurate assessment of prognosis and individualized treatment. Furthermore, recent developments that have been applied to a narrow group of patients with IPF may be applicable to those with other progressive fibrotic lung diseases. This review presents the latest developments from translational research in this area and explains how molecular endotyping could revolutionize the diagnosis, stratification, and treatment of pulmonary fibrosis.

  3. Molecular Modeling of Estrogen Receptor Using Molecular Operating Environment

    ERIC Educational Resources Information Center

    Roy, Urmi; Luck, Linda A.

    2007-01-01

    Molecular modeling is pervasive in the pharmaceutical industry that employs many of our students from Biology, Chemistry and the interdisciplinary majors. To expose our students to this important aspect of their education we have incorporated a set of tutorials in our Biochemistry class. The present article describes one of our tutorials where…

  4. Studies on molecular recognition of thymidines with molecularly imprinted polymers

    NASA Astrophysics Data System (ADS)

    Chen, Zhen-He; Luo, Ai-Qin; Sun, Li-Quan

    2009-07-01

    Molecularly imprinted polymers (MIPs) with excellent molecular recognition ability have been used in chemical sensors, chromatographic separation and biochemical analyses. Thymidine is an important part of DNA for biomolecular recognition and the intermediate of many medicines. The polymers imprinted with the template of thymidine and 5'-Otosylthymidine have been prepared, using a non-proton solvent, acetonitrile as the porogen. Direct imprinting with thymidine could not form strong molecular interaction sites in this system. Relative MIPs were obtained by bulk polymerization and their adsorption capacities were investigated. The adsorption capacities of MIP (P2) and nonimprinted polymer (P20) for thymidine are 0.120 mg•g-1and 0.103 mg•g-1, respectively. The imprinting factor is 1.17. As 5'-O-tosylthymidine is more soluble than thymidine moiety in acetonitrile and give rise to more sites of molecular recognition. The results demonstrated that the imprinted polymers were able to bind and recognize thymidine moderately in acetonitrile. MIPs imprinted with 5'-O-tosylthymidine like nature enzymes displayed some recognition ability to its analogues. The insoluble derivatives in the non-proton solvent can be an effective template to prepare efficient imprinting recognition sites.

  5. Molecular pathophysiology of cerebral edema

    PubMed Central

    Gerzanich, Volodymyr; Simard, J Marc

    2015-01-01

    Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema. PMID:26661240

  6. Model Pores of Molecular Dimension

    PubMed Central

    Quinn, J. A.; Anderson, J. L.; Ho, W. S.; Petzny, W. J.

    1972-01-01

    Extremely uniform pores of near molecular dimension can be formed by the irradiation-etching technique first demonstrated by Price and Walker. The technique has now been developed to the stage where it can be used to fabricate model membranes for examining the various steric, hydrodynamic, and electrodynamic phenomena encountered in transport through molecular-size pores. Methods for preparing and characterizing membranes with pores as small as 25 A (radius) are described in this paper. Results on pore size determination via Knudsen gas flow and electrolyte conduction are compared. Pore wall modification by monolayer deposition is also discussed. PMID:4339801

  7. Molecular mechanisms of neurite extension.

    PubMed Central

    Valtorta, F; Leoni, C

    1999-01-01

    The extension of neurites is a major task of developing neurons, requiring a significant metabolic effort to sustain the increase in molecular synthesis necessary for plasma membrane expansion. In addition, neurite extension involves changes in the subsets of expressed proteins and reorganization of the cytomatrix. These phenomena are driven by environmental cues which activate signal transduction processes as well as by the intrinsic genetic program of the cell. The present review summarizes some of the most recent progress made in the elucidation of the molecular mechanisms underlying these processes. PMID:10212488

  8. Molecular pathophysiology of cerebral edema.

    PubMed

    Stokum, Jesse A; Gerzanich, Volodymyr; Simard, J Marc

    2016-03-01

    Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema.

  9. Molecular Biomarkers of Knee Pathology.

    PubMed

    Cuellar, Vanessa; Strauss, Eric

    2017-01-01

    The identification of biomarkers has become increasingly important in our fundamental understanding of the molecular basis for disease and subsequently in the advancement of modern medicine. Biomarkers have been identified in a plethora of normal and pathologic conditions and are most often found in blood, tissue, or synovial fluid. Orthopaedic research has more recently focused on biomarkers of cartilage and joint diseases, with an emphasis on understanding the molecular underpinnings of their pathophysiology. This article focuses on the biomarkers identified to date in several select knee pathologies and how further research can contribute to new diagnostic tools and targeted therapeutics.

  10. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  11. Molecular Motors and Stochastic Models

    NASA Astrophysics Data System (ADS)

    Lipowsky, Reinhard

    The behavior of single molecular motors such as kinesin or myosin V, which move on linear filaments, involves a nontrivial coupling between the biochemical motor cycle and the stochastic movement. This coupling can be studied in the framework of nonuniform ratchet models which are characterized by spatially localized transition rates between the different internal states of the motor. These models can be classified according to their functional relationships between the motor velocity and the concentration of the fuel molecules. The simplest such relationship applies to two subclasses of models for dimeric kinesin and agrees with experimental observations on this molecular motor.

  12. Molecular catalytic coal liquid conversion

    SciTech Connect

    Stock, L.M.; Yang, Shiyong

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  13. Cardiotoxicity of Molecularly Targeted Agents

    PubMed Central

    Hedhli, Nadia; Russell, Kerry S

    2011-01-01

    Cardiac toxicity of molecularly targeted cancer agents is increasingly recognized as a significant side effect of chemotherapy. These new potent therapies may not only affect the survival of cancer cells, but have the potential to adversely impact normal cardiac and vascular function. Unraveling the mechanisms by which these therapies affect the heart and vasculature is crucial for improving drug design and finding alternative therapies to protect patients predisposed to cardiovascular disease. In this review, we summarize the classification and side effects of currently approved molecularly targeted chemotherapeutics. PMID:22758623

  14. Water in dense molecular clouds

    NASA Technical Reports Server (NTRS)

    Wannier, P. G.; Kuiper, T. B. H.; Frerking, M. A.; Gulkis, S.; Pickett, H. M.; Wilson, W. J.; Pagani, L.; Lecacheux, A.; Encrenaz, P.

    1991-01-01

    The G.P. Kuiper Airborne Observatory (KAO) was used to make initial observations of the half-millimeter ground-state transition of water in seven giant molecular clouds and in two late-type stars. No significant detections were made, and the resulting upper limits are significantly below those expected from other, indirect observations and from several theoretical models. The implied interstellar H2O/CO abundance is less than 0.003 in the cores of three giant molecular clouds. This value is less than expected from cloud chemistry models and also than estimates based on HDO and H3O(+) observations.

  15. [MOLECULAR ASPECTS OF BRUCELLA PERSISTENCE].

    PubMed

    Kulakov Yu K

    2016-01-01

    Brucellosis is a dangerous zoonotic disease of animals and humans caused by bacteria of the genus Brucella, which are able to survive, multiply, and persist in host cells. The review is devoted to the Brucella species persistence connected to the molecular mechanisms of escape from innate and adaptive immunity of the host and active interaction of effector proteins of the type IV secretion system with the host's signaling pathways. Understanding of the molecular mechanisms used by Brucella for the intracellular persistence in the host organism can allow us to develop new and effective means for the prevention and treatment of chronic brucellosis infection.

  16. Electrostatics at the molecular level

    NASA Astrophysics Data System (ADS)

    Zürcher, Ulrich

    2017-01-01

    In molecular systems, positive and negative charges are separated, making them ideal systems to examine electrostatic interactions. The attractive force between positive and negative charges is balanced by repulsive ‘forces’ that are quantum-mechanical in origin. We introduce an ‘effective’ potential energy that captures the repulsion; it allows us to obtain fairly accurate estimates of the bonding properties of molecular systems. We use units (e.g., kcal mol-1 for energy) that emphasize the relevance of electrostatics to macroscopic behavior.

  17. Disseminated Medulloblastoma in a Child with Germline BRCA2 6174delT Mutation and without Fanconi Anemia

    PubMed Central

    Xu, Jingying; Margol, Ashley Sloane; Shukla, Anju; Ren, Xiuhai; Finlay, Jonathan L.; Krieger, Mark D.; Gilles, Floyd H.; Couch, Fergus J.; Aziz, Meraj; Fung, Eric T.; Asgharzadeh, Shahab; Barrett, Michael T.; Erdreich-Epstein, Anat

    2015-01-01

    Medulloblastoma, the most common malignant brain tumor in children, occurs with increased frequency in individuals with Fanconi anemia who have biallelic germline mutations in BRCA2. We describe an 8-year-old child who had disseminated anaplastic medulloblastoma and a deleterious heterozygous BRCA2 6174delT germline mutation. Molecular profiling was consistent with Group 4 medulloblastoma. The posterior fossa mass was resected and the patient received intensive chemotherapy and craniospinal irradiation. Despite this, the patient succumbed to a second recurrence of his medulloblastoma, which presented 8 months after diagnosis as malignant pleural and peritoneal effusions. Continuous medulloblastoma cell lines were isolated from the original tumor (CHLA-01-MED) and the malignant pleural effusion (CHLA-01R-MED). Here, we provide their analyses, including in vitro and in vivo growth, drug sensitivity, comparative genomic hybridization, and next generation sequencing analysis. In addition to the BRCA2 6174delT, the medulloblastoma cells had amplification of MYC, deletion at Xp11.2, and isochromosome 17, but no structural variations or overexpression of GFI1 or GFI1B. To our knowledge, this is the first pair of diagnosis/recurrence medulloblastoma cell lines, the only medulloblastoma cell lines with BRCA2 6174delT described to date, and the first reported case of a child with medulloblastoma associated with a germline BRCA2 6174delT who did not also have Fanconi anemia. PMID:26380221

  18. Evaluación de la utilidad diagnóstica de la versión española del cuestionario al informador «AD8»☆

    PubMed Central

    Pardo, C. Carnero; de la Vega Cotarelo, R.; Alcalde, S. López; Aparicio, C. Martos; Carrillo, R. Vílchez; Gavilán, E. Mora; Galvin, J.E.

    2012-01-01

    Introducción El AD8 es un cuestionario al informador breve que puede ser autoaplicado y facilita la identificación de deterioro cognitivo (DC); nuestro objetivo es evaluar la utilidad diagnóstica (UD) de una versión española. Material y métodos Estudio transversal en una muestra clínica de díadas paciente/ informador, 330 sujetos con sospecha de DC o demencia (DEM) y 71 controles. Se ha evaluado la consistencia interna (α de Cronbach) y la validez (correlaciones parciales con estadio GDS, Fototest e índice funcional [IF]). La UD se ha evaluado para no DC vs DC (GDS 3–4) por medio del área bajo la curva ROC (aROC) y se ha considerado mejor punto de corte aquel que hacía máximo el índice de Youden. Resultados En la muestra, 105 no tenían DC, 99 tenían DC sin DEM y 203 DEM. La consistencia interna es alta (α 0,90, IC del 95%, 0,89–0,92), al igual que las correlaciones con GDS (r = 0,72, p < 0,001), Fototest (r = −0,61, p < 0,001) e IF (r = 0,59, p < 0,001). El aROC del AD8 es 0,90 (IC del 95%, 0,86–0,93), sin diferencia significativa con la del Fototest (aROC 0,93, IC del 95%, 0,89–0,96); el mejor punto de corte es 3/4 con sensibilidad de 0,93 (IC del 95%, 0,88–0,96), especificidad de 0,81 (IC del 95%, 0,72–0,88) y el 88,8% de las clasificaciones correctas. El uso conjunto de AD8 y Fototest mejora de forma significativa la UD de ambos (aROC 0,96, IC del 95%, 0,93–0,98, p < 0,05). Conclusiones La versión española del AD8 conserva las cualidades psicométricas y la UD de la versión original; su uso combinado con el Fototest mejora de forma significativa la UD de ambos. PMID:22652137

  19. Del Norte means north to recycling

    SciTech Connect

    Aquino, J.T.

    1998-06-01

    Del Norte Regional Recycling and Transfer Station is owned by the city of Oxnard, California and operated by BLT Enterprises, Inc. The Del Norte facility--located in southwestern Ventura County about an hour northwest of Los Angeles--processes polyethylene terephthalate (PET) and high-density polyethylene (HDPE) plastic containers, aluminum, steel, glass, old corrugated containers (OCC), newspapers, computer printout paper, white and colored ledger paper, coated book, supermix paper, telephone books, and old magazines. According to the company, there has been virtually no community opposition to the site. The facility has few neighbors, and those are agricultural. To keep the community relationship strong, the facility`s design and location all but eliminated odor and noise complaints. The building was designed against the prevailing wind pattern, and BLT processes odorous material fast. A misting system installed for dust suppression also can be used with a solution for odor control should the need arise.

  20. The Molecular Basis of Development.

    ERIC Educational Resources Information Center

    Gehring, Walter J.

    1985-01-01

    Basic architecture of embryo development appears to be under homeobox control (a short stretch of DNA). Outlines research on this genetic segment in fruit flies which led to identification of this control on the embryo's spatial organization. Indicates that molecular mechanisms underlying development may be much more universal than previously…

  1. Small Molecular as SIRT Modulators.

    PubMed

    Yao, Lei; Xu, Xiangming; Chen, Kai

    2016-06-19

    Sirtuins are class III histone deacetylases, they involve in many important biological functions. Small molecules that can modulate sirtuin activity have been shown to have potential for treating many human diseases. In the article, recent development of small molecular as SIRT modulators has been reviewed.

  2. Molecular signatures of major depression.

    PubMed

    Cai, Na; Chang, Simon; Li, Yihan; Li, Qibin; Hu, Jingchu; Liang, Jieqin; Song, Li; Kretzschmar, Warren; Gan, Xiangchao; Nicod, Jerome; Rivera, Margarita; Deng, Hong; Du, Bo; Li, Keqing; Sang, Wenhu; Gao, Jingfang; Gao, Shugui; Ha, Baowei; Ho, Hung-Yao; Hu, Chunmei; Hu, Jian; Hu, Zhenfei; Huang, Guoping; Jiang, Guoqing; Jiang, Tao; Jin, Wei; Li, Gongying; Li, Kan; Li, Yi; Li, Yingrui; Li, Youhui; Lin, Yu-Ting; Liu, Lanfen; Liu, Tiebang; Liu, Ying; Liu, Yuan; Lu, Yao; Lv, Luxian; Meng, Huaqing; Qian, Puyi; Sang, Hong; Shen, Jianhua; Shi, Jianguo; Sun, Jing; Tao, Ming; Wang, Gang; Wang, Guangbiao; Wang, Jian; Wang, Linmao; Wang, Xueyi; Wang, Xumei; Yang, Huanming; Yang, Lijun; Yin, Ye; Zhang, Jinbei; Zhang, Kerang; Sun, Ning; Zhang, Wei; Zhang, Xiuqing; Zhang, Zhen; Zhong, Hui; Breen, Gerome; Wang, Jun; Marchini, Jonathan; Chen, Yiping; Xu, Qi; Xu, Xun; Mott, Richard; Huang, Guo-Jen; Kendler, Kenneth; Flint, Jonathan

    2015-05-04

    Adversity, particularly in early life, can cause illness. Clues to the responsible mechanisms may lie with the discovery of molecular signatures of stress, some of which include alterations to an individual's somatic genome. Here, using genome sequences from 11,670 women, we observed a highly significant association between a stress-related disease, major depression, and the amount of mtDNA (p = 9.00 × 10(-42), odds ratio 1.33 [95% confidence interval [CI] = 1.29-1.37]) and telomere length (p = 2.84 × 10(-14), odds ratio 0.85 [95% CI = 0.81-0.89]). While both telomere length and mtDNA amount were associated with adverse life events, conditional regression analyses showed the molecular changes were contingent on the depressed state. We tested this hypothesis with experiments in mice, demonstrating that stress causes both molecular changes, which are partly reversible and can be elicited by the administration of corticosterone. Together, these results demonstrate that changes in the amount of mtDNA and telomere length are consequences of stress and entering a depressed state. These findings identify increased amounts of mtDNA as a molecular marker of MD and have important implications for understanding how stress causes the disease.

  3. Molecular Foundry, Berkeley, California (Revised)

    SciTech Connect

    Carlisle, N.

    2008-03-01

    This case study provides information on the Molecular Foundry, which incorporates Labs21 principles in its design and construction. The design includes many of the strategies researched at Lawrence Berkeley Laboratory for energy efficient cleanroom and data centers. The result is an energy efficient high-performing sustainable laboratory.

  4. A Molecular Basis of Cancer.

    ERIC Educational Resources Information Center

    Weinberg, Robert A.

    1983-01-01

    Discusses the molecular basis of cancer, focusing on genetics of the disease. Indicates that human cancers are initiated by oncogenes (altered versions of normal genes) and that in one case the critical alteration is a single point mutation that changes one amino acid in the protein encoded by the gene. (JN)

  5. [Quality control in molecular microbiology].

    PubMed

    Orta Mira, Nieves; Guna Serrano, María Remedio; Gimeno Cardona, Concepción; Pérez, José L

    2008-07-01

    The term quality assurance (QA) refers to the quality control activities related to analytical procedures performed in the clinical microbiology laboratory. QA should include both external and internal quality assessment. Application of quality control tools in molecular microbiology assays is crucial to ensure the accuracy of results and appropriate patient management. External quality control is used for laboratory intercomparisons, detection of random and systematic errors, evaluation of the suitability of some reagents or commercial diagnostic kits, and continuing education. The External Quality Control Program of the Spanish Society of Infectious Diseases and Clinical Microbiology includes quality control procedures for molecular microbiology, as well as specific programs for quantitative determination of the viral load of human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV), two highly important molecular markers in clinical settings due to their prognostic value and utility as a treatment guide. Internal quality control allows random and systematic errors to be detected through the inclusion of quality control samples in the assays performed in the laboratory, equipment monitoring, and audit. Evaluation of all molecular microbiology assays before their inclusion in the daily routine work of the laboratory is of utmost importance.

  6. Molecular Size and Raoult's Law.

    ERIC Educational Resources Information Center

    Kovac, Jeffrey

    1985-01-01

    The concept of an ideal solution is ordinarily introduced in freshman chemistry by means of Raoult's Law, which states that the vapor pressure of a volatile component of a solution is proportional to its mole fraction. The relationship of this law to molecular size is discussed. (JN)

  7. Thermoelectric efficiency of molecular junctions.

    PubMed

    Perroni, C A; Ninno, D; Cataudella, V

    2016-09-21

    Focus of the review is on experimental set-ups and theoretical proposals aimed to enhance thermoelectric performances of molecular junctions. In addition to charge conductance, the thermoelectric parameter commonly measured in these systems is the thermopower, which is typically rather low. We review recent experimental outcomes relative to several junction configurations used to optimize the thermopower. On the other hand, theoretical calculations provide estimations of all the thermoelectric parameters in the linear and non-linear regime, in particular of the thermoelectric figure of merit and efficiency, completing our knowledge of molecular thermoelectricity. For this reason, the review will mainly focus on theoretical studies analyzing the role of not only electronic, but also of the vibrational degrees of freedom. Theoretical results about thermoelectric phenomena in the coherent regime are reviewed focusing on interference effects which play a significant role in enhancing the figure of merit. Moreover, we review theoretical studies including the effects of molecular many-body interactions, such as electron-vibration couplings, which typically tend to reduce the efficiency. Since a fine tuning of many parameters and coupling strengths is required to optimize the thermoelectric conversion in molecular junctions, new theoretically proposed set-ups are discussed in the conclusions.

  8. Molecular outflows in starburst nuclei

    NASA Astrophysics Data System (ADS)

    Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-12-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disc with mid-plane density n0 ˜ 200-1000 cm-3 and scaleheight z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that an SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  9. Fluctuation Relations for Molecular Motors

    NASA Astrophysics Data System (ADS)

    Lacoste, David; Mallick, Kirone

    This review is focused on the application of specific fluctuation relations, such as the Gallavotti-Cohen relation, to ratchet models of a molecular motor. A special emphasis is placed on two-state models such as the flashing ratchet model. We derive the Gallavotti-Cohen fluctuation relation for these models and we discuss some of its implications.

  10. Molecular Ecology of Drinking Water

    EPA Science Inventory

    The presentation consists of examples of molecular research: –Detection and control (removal and/or inactivation) of microbes in drinking source waters –Changing microbial quality of water during distribution and storage –Detection and identification of microbial agents, incl...

  11. Papillomaviruses: Molecular and clinical aspects

    SciTech Connect

    Howley, P.M.; Broker, T.R.

    1985-01-01

    This book contains nine sections, each consisting of several papers. The section headings are : Papillomaviruses and Human Genital Tract Diseases;Papillomaviruses and Human Cutaneous Diseases, Papillomaviruses and Human Oral and Laryngeal Diseases;Therapeutic Approaches to Papillomavirus Infections;Animal Papillomaviruses;Molecular Biology;Transcription, Replication, and Genome Organization;Epithelial Cell Culture;Papillomavirus Transformation;and Viral Vectors.

  12. Scaffolding Learning from Molecular Visualizations

    ERIC Educational Resources Information Center

    Chang, Hsin-Yi; Linn, Marcia C.

    2013-01-01

    Powerful online visualizations can make unobservable scientific phenomena visible and improve student understanding. Instead, they often confuse or mislead students. To clarify the impact of molecular visualizations for middle school students we explored three design variations implemented in a Web-based Inquiry Science Environment (WISE) unit on…

  13. Sarcoidosis, cancer and molecular mimicry.

    PubMed

    Tchernev, G; Wollina, U

    2013-01-01

    Molecular mimicry seems to be the most important factor for the heterogeneous clinical presentation and the immunopathogenesis of sarcoidosis. Molecular mimicry may occur as a result of altered activity of oncogenes. This can lead to crossed-type mediated body reactions targeting structurally similar sections or regions from the tissue homeostasis. Available data suggest that structural analogy between tissue and foreign or de novo-appearing peptides is not always reliable. Nevertheless, lack of amino acid identity between the tissue and the de novo-generated tumour antigens does not exclude the phenomenon of molecular mimicry as the major generator of sarcoidosis. There is growing evidence of the mimicry phenomena, caused not only by the similarity between the amino acids but also between the elements which connect segments in the immunological cascade and which may also be affected by external factors. Molecular mimicry may occur between two identified peptides having similar antigenic surfaces (transitory or not), in the absence of a primary homology in amino acid sequence. As far as tumour antigens are concerned, a structural analogy to the de novo-appearing tumour antigens is more likely than transitory imitation resulting from the additional interference of other physical forces. Further research should be performed to confirm, or reject, the transitory imitation thesis or hypothesis.

  14. Alligator clips to molecular dimensions

    NASA Astrophysics Data System (ADS)

    Prokopuk, Nicholas; Son, Kyung-Ah

    2008-09-01

    Techniques for fabricating nanospaced electrodes suitable for studying electron tunneling through metal-molecule-metal junctions are described. In one approach, top contacts are deposited/placed on a self-assembled monolayer or Langmuir-Blodgett film resting on a conducting substrate, the bottom contact. The molecular component serves as a permanent spacer that controls and limits the electrode separations. The top contact can be a thermally deposited metal film, liquid mercury drop, scanning probe tip, metallic wire or particle. Introduction of the top contact can greatly affect the electrical conductance of the intervening molecular film by chemical reaction, exerting pressure, or simply migrating through the organic layer. Alternatively, vacant nanogaps can be fabricated and the molecular component subsequently inserted. Strategies for constructing vacant nanogaps include mechanical break junction, electromigration, shadow mask lithography, focused ion beam deposition, chemical and electrochemical plating techniques, electron-beam lithography, and molecular and atomic rulers. The size of the nanogaps must be small enough to allow the molecule to connect both leads and large enough to keep the molecules in a relaxed and undistorted state. A significant advantage of using vacant nanogaps in the construction of metal-molecule-metal devices is that the junction can be characterized with and without the molecule in place. Any electrical artifacts introduced by the electrode fabrication process are more easily deconvoluted from the intrinsic properties of the molecule.

  15. Instructional Technology and Molecular Visualization

    ERIC Educational Resources Information Center

    Appling, Jeffrey R.; Peake, Lisa C.

    2004-01-01

    The effect of intervening use of molecular visualization software was tested on 73 first-year general chemistry students. Pretests and posttests included both traditional multiple-choice questions and model-building activities. Overall students improved after working with the software, although students performed less well on the model-building…

  16. Theoretical Studies of Molecular Spectra

    NASA Technical Reports Server (NTRS)

    McKay, Christopher (Technical Monitor); Freedman, Richard S.

    2002-01-01

    This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

  17. Molecular Signatures of Major Depression

    PubMed Central

    Cai, Na; Chang, Simon; Li, Yihan; Li, Qibin; Hu, Jingchu; Liang, Jieqin; Song, Li; Kretzschmar, Warren; Gan, Xiangchao; Nicod, Jerome; Rivera, Margarita; Deng, Hong; Du, Bo; Li, Keqing; Sang, Wenhu; Gao, Jingfang; Gao, Shugui; Ha, Baowei; Ho, Hung-Yao; Hu, Chunmei; Hu, Jian; Hu, Zhenfei; Huang, Guoping; Jiang, Guoqing; Jiang, Tao; Jin, Wei; Li, Gongying; Li, Kan; Li, Yi; Li, Yingrui; Li, Youhui; Lin, Yu-Ting; Liu, Lanfen; Liu, Tiebang; Liu, Ying; Liu, Yuan; Lu, Yao; Lv, Luxian; Meng, Huaqing; Qian, Puyi; Sang, Hong; Shen, Jianhua; Shi, Jianguo; Sun, Jing; Tao, Ming; Wang, Gang; Wang, Guangbiao; Wang, Jian; Wang, Linmao; Wang, Xueyi; Wang, Xumei; Yang, Huanming; Yang, Lijun; Yin, Ye; Zhang, Jinbei; Zhang, Kerang; Sun, Ning; Zhang, Wei; Zhang, Xiuqing; Zhang, Zhen; Zhong, Hui; Breen, Gerome; Wang, Jun; Marchini, Jonathan; Chen, Yiping; Xu, Qi; Xu, Xun; Mott, Richard; Huang, Guo-Jen; Kendler, Kenneth; Flint, Jonathan

    2015-01-01

    Summary Adversity, particularly in early life, can cause illness. Clues to the responsible mechanisms may lie with the discovery of molecular signatures of stress, some of which include alterations to an individual’s somatic genome. Here, using genome sequences from 11,670 women, we observed a highly significant association between a stress-related disease, major depression, and the amount of mtDNA (p = 9.00 × 10−42, odds ratio 1.33 [95% confidence interval [CI] = 1.29–1.37]) and telomere length (p = 2.84 × 10−14, odds ratio 0.85 [95% CI = 0.81–0.89]). While both telomere length and mtDNA amount were associated with adverse life events, conditional regression analyses showed the molecular changes were contingent on the depressed state. We tested this hypothesis with experiments in mice, demonstrating that stress causes both molecular changes, which are partly reversible and can be elicited by the administration of corticosterone. Together, these results demonstrate that changes in the amount of mtDNA and telomere length are consequences of stress and entering a depressed state. These findings identify increased amounts of mtDNA as a molecular marker of MD and have important implications for understanding how stress causes the disease. PMID:25913401

  18. Measurement Frontiers in Molecular Biology

    NASA Astrophysics Data System (ADS)

    Laderman, Stephen

    2009-03-01

    Developments of molecular measurements and manipulations have long enabled forefront research in evolution, genetics, biological development and its dysfunction, and the impact of external factors on the behavior of cells. Measurement remains at the heart of exciting and challenging basic and applied problems in molecular and cell biology. Methods to precisely determine the identity and abundance of particular molecules amongst a complex mixture of similar and dissimilar types require the successful design and integration of multiple steps involving biochemical manipulations, separations, physical probing, and data processing. Accordingly, today's most powerful methods for characterizing life at the molecular level depend on coordinated advances in applied physics, biochemistry, chemistry, computer science, and engineering. This is well illustrated by recent approaches to the measurement of DNA, RNA, proteins, and intact cells. Such successes underlie well founded visions of how molecular biology can further assist in answering compelling scientific questions and in enabling the development of remarkable advances in human health. These visions, in turn, are motivating the interdisciplinary creation of even more comprehensive measurements. As a further and closely related consequence, they are motivating innovations in the conceptual and practical approaches to organizing and visualizing large, complex sets of interrelated experimental results and distilling from those data compelling, informative conclusions.

  19. Molecular dynamics of silicon indentation

    NASA Astrophysics Data System (ADS)

    Kallman, J. S.; Hoover, W. G.; Hoover, C. G.; de Groot, A. J.; Lee, S. M.; Wooten, F.

    1993-04-01

    We use nonequilibrium molecular dynamics to simulate the elastic-plastic deformation of silicon under tetrahedral nanometer-sized indentors. The results are described in terms of a rate-dependent and temperature-dependent phenomenological yield strength. We follow the structural change during indentation with a computer technique that allows us to model the dynamic simulation of diffraction patterns.

  20. Circadian rhythms and molecular noise

    NASA Astrophysics Data System (ADS)

    Gonze, Didier; Goldbeter, Albert

    2006-06-01

    Circadian rhythms, characterized by a period of about 24h, are the most widespread biological rhythms generated autonomously at the molecular level. The core molecular mechanism responsible for circadian oscillations relies on the negative regulation exerted by a protein on the expression of its own gene. Deterministic models account for the occurrence of autonomous circadian oscillations, for their entrainment by light-dark cycles, and for their phase shifting by light pulses. Stochastic versions of these models take into consideration the molecular fluctuations that arise when the number of molecules involved in the regulatory mechanism is low. Numerical simulations of the stochastic models show that robust circadian oscillations can already occur with a limited number of mRNA and protein molecules, in the range of a few tens and hundreds, respectively. Various factors affect the robustness of circadian oscillations with respect to molecular noise. Besides an increase in the number of molecules, entrainment by light-dark cycles, and cooperativity in repression enhance robustness, whereas the proximity of a bifurcation point leads to less robust oscillations. Another parameter that appears to be crucial for the coherence of circadian rhythms is the binding/unbinding rate of the inhibitory protein to the promoter of the clock gene. Intercellular coupling further increases the robustness of circadian oscillations.

  1. Space station molecular sieve development

    NASA Technical Reports Server (NTRS)

    Chang, C.; Rousseau, J.

    1986-01-01

    An essential function of a space environmental control system is the removal of carbon dioxide (CO2) from the atmosphere to control the partial pressure of this gas at levels lower than 3 mm Hg. The use of regenerable solid adsorbents for this purpose was demonstrated effectively during the Skylab mission. Earlier sorbent systems used zeolite molecular sieves. The carbon molecular sieve is a hydrophobic adsorbent with excellent potential for space station application. Although carbon molecular sieves were synthesized and investigated, these sieves were designed to simulate the sieving properties of 5A zeolite and for O2/N2 separation. This program was designed to develop hydrophobic carbon molecular sieves for CO2 removal from a space station crew environment. It is a first phase effort involved in sorbent material development and in demonstrating the utility of such a material for CO2 removal on space stations. The sieve must incorporate the following requirements: it must be hydrophobic; it must have high dynamic capacity for carbon dioxide at the low partial pressure of the space station atmosphere; and it must be chemiclly stable and will not generate contaminants.

  2. Cancer Stratification by Molecular Imaging

    PubMed Central

    Weber, Justus; Haberkorn, Uwe; Mier, Walter

    2015-01-01

    The lack of specificity of traditional cytotoxic drugs has triggered the development of anticancer agents that selectively address specific molecular targets. An intrinsic property of these specialized drugs is their limited applicability for specific patient subgroups. Consequently, the generation of information about tumor characteristics is the key to exploit the potential of these drugs. Currently, cancer stratification relies on three approaches: Gene expression analysis and cancer proteomics, immunohistochemistry and molecular imaging. In order to enable the precise localization of functionally expressed targets, molecular imaging combines highly selective biomarkers and intense signal sources. Thus, cancer stratification and localization are performed simultaneously. Many cancer types are characterized by altered receptor expression, such as somatostatin receptors, folate receptors or Her2 (human epidermal growth factor receptor 2). Similar correlations are also known for a multitude of transporters, such as glucose transporters, amino acid transporters or hNIS (human sodium iodide symporter), as well as cell specific proteins, such as the prostate specific membrane antigen, integrins, and CD20. This review provides a comprehensive description of the methods, targets and agents used in molecular imaging, to outline their application for cancer stratification. Emphasis is placed on radiotracers which are used to identify altered expression patterns of cancer associated markers. PMID:25749472

  3. Procesamiento Digital de Imagenes del Cometa Halley

    NASA Astrophysics Data System (ADS)

    Ferrin, L.; Fuenmayor, F.; Naranjo, O.; Bulka, P.; Mendoza, C.

    1987-05-01

    Se reportan observaciones fotográficas del cometa Halley, obtenidas con los telescopios Schmidt de 1-m del CIDA, y de 35 cms de la ULA. Se hicieron exposiciones desde 2 segundos a 30 minutos y se utilizaron emulsiones IIa-O, 103a-F, y 103a-D, guladas manualmente 0 automaticámente. Las imágenes fueron digitalizadas con el microdensitómetro PDS, y procesadas con el sistema HACIENDA del CCIBM. Se experimentó con la Transformada de Fourier en dos dimensiones, y con la aplicación de filtros de paso alto y bajo. Se encontró que el metodo de "autocorrelación" es el mejor para separar "la vegetación" de "la montaña". Se aplicaron diversas técnicas a fin de cubrir ambos extremos: a) enfatizar detalles débiles en la cola, y b) penetrar en las regiones más intensas de la coma. Se lograron ambos objetivos. Detalles en la cola permitieron determinar velocidades de propagación de unos 50 a 90 kms/ seg. Se pudieron detectar no menos de tres perturbaciones en "Y", y una en 5? Co de Cisne). Se cree que las primeras están asociadas a eventos de desconexión. Se puede separar la cola de gas de la de polvo. Las fotos de color permiten enfatizar diferentes regiones espectrales con mayor claridad aún. El "balance" del color puede ser hecho con la computadora.

  4. Rotaxane-based molecular muscles.

    PubMed

    Bruns, Carson J; Stoddart, J Fraser

    2014-07-15

    CONSPECTUS: More than two decades of investigating the chemistry of bistable mechanically interlocked molecules (MIMs), such as rotaxanes and catenanes, has led to the advent of numerous molecular switches that express controlled translational or circumrotational movement on the nanoscale. Directed motion at this scale is an essential feature of many biomolecular assemblies known as molecular machines, which carry out essential life-sustaining functions of the cell. It follows that the use of bistable MIMs as artificial molecular machines (AMMs) has been long anticipated. This objective is rarely achieved, however, because of challenges associated with coupling the directed motions of mechanical switches with other systems on which they can perform work. A natural source of inspiration for designing AMMs is muscle tissue, since it is a material that relies on the hierarchical organization of molecular machines (myosin) and filaments (actin) to produce the force and motion that underpin locomotion, circulation, digestion, and many other essential life processes in humans and other animals. Muscle is characterized at both microscopic and macroscopic length scales by its ability to generate forces that vary the distance between two points at the expense of chemical energy. Artificial muscles that mimic this ability are highly sought for applications involving the transduction of mechanical energy. Rotaxane-based molecular switches are excellent candidates for artificial muscles because their architectures intrinsically possess movable filamentous molecular components. In this Account, we describe (i) the different types of rotaxane "molecular muscle" architectures that express contractile and extensile motion, (ii) the molecular recognition motifs and corresponding stimuli that have been used to actuate them, and (iii) the progress made on integrating and scaling up these motions for potential applications. We identify three types of rotaxane muscles, namely, "daisy

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

    NASA Astrophysics Data System (ADS)

    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).

  6. Light-driven artificial molecular machines

    NASA Astrophysics Data System (ADS)

    Zheng, Yue Bing; Hao, Qingzhen; Yang, Ying-Wei; Kiraly, Brian; Chiang, I.-Kao; Huang, Tony Jun

    2010-08-01

    Artificial molecular machines represent a growing field of nanoscience and nanotechnology. Stimulated by chemical reagents, electricity, or light, artificial molecular machines exhibit precisely controlled motion at the molecular level; with this ability molecular machines have the potential to make significant impacts in numerous engineering applications. Compared with molecular machines powered by chemical or electrical energy, light-driven molecular machines have several advantages: light can be switched much faster, work without producing chemical waste, and be used for dual purposes-inducing (writing) as well as detecting (reading) molecular motions. The following issues are significant for light-driven artificial molecular machines in the following aspects: their chemical structures, motion mechanisms, assembly and characterization on solid-state surfaces. Applications in different fields of nanotechnology such as molecular electronics, nano-electro-mechanical systems (NEMS), nanophotonics, and nanomedicine are envisaged.

  7. Molecular Testing for Gastrointestinal Cancer

    PubMed Central

    Lee, Hye Seung; Kim, Woo Ho; Kwak, Yoonjin; Koh, Jiwon; Bae, Jeong Mo; Kim, Kyoung-Mee; Chang, Mee Soo; Han, Hye Seung; Kim, Joon Mee; Kim, Hwal Woong; Chang, Hee Kyung; Choi, Young Hee; Park, Ji Y.; Gu, Mi Jin; Lhee, Min Jin; Kim, Jung Yeon; Kim, Hee Sung; Cho, Mee-Yon

    2017-01-01

    With recent advances in molecular diagnostic methods and targeted cancer therapies, several molecular tests have been recommended for gastric cancer (GC) and colorectal cancer (CRC). Microsatellite instability analysis of gastrointestinal cancers is performed to screen for Lynch syndrome, predict favorable prognosis, and screen patients for immunotherapy. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor has been approved in metastatic CRCs with wildtype RAS (KRAS and NRAS exon 2–4). A BRAF mutation is required for predicting poor prognosis. Additionally, amplification of human epidermal growth factor receptor 2 (HER2) and MET is also associated with resistance to EGFR inhibitor in metastatic CRC patients. The BRAF V600E mutation is found in sporadic microsatellite unstable CRCs, and thus is helpful for ruling out Lynch syndrome. In addition, the KRAS mutation is a prognostic biomarker and the PIK3CA mutation is a molecular biomarker predicting response to phosphoinositide 3-kinase/AKT/mammalian target of rapamycin inhibitors and response to aspirin therapy in CRC patients. Additionally, HER2 testing should be performed in all recurrent or metastatic GCs. If the results of HER2 immunohistochemistry are equivocal, HER2 silver or fluorescence in situ hybridization testing are essential for confirmative determination of HER2 status. Epstein-Barr virus–positive GCs have distinct characteristics, including heavy lymphoid stroma, hypermethylation phenotype, and high expression of immune modulators. Recent advances in next-generation sequencing technologies enable us to examine various genetic alterations using a single test. Pathologists play a crucial role in ensuring reliable molecular testing and they should also take an integral role between molecular laboratories and clinicians. PMID:28219002

  8. Ultrasonic attenuation in molecular crystals

    NASA Astrophysics Data System (ADS)

    Perrin, Bernard

    1981-11-01

    It is now well established from an experimental point of view that, concerning the ultrasonic attenuation, molecular crystals exhibit a specific behavior among dielectric crystals. This fact suggests the presence of a relaxation process. Liebermann, who has introduced this field, has proposed a way to analyze this problem and in particular has given an expression for the ultrasonic absorption coefficient in terms of a relaxation time and some thermodynamic quantities. In contrast to Liebermann's approach, a solid-state viewpoint is presented here, and it is shown that this ultrasonic relaxation can be taken into account in the framework of Akhieser's theory. A general expression of the ultrasonic absorption coefficient is calculated in terms of the phonon collision operator using the Boltzmann-equation approach of Woodruff and Ehrenreich. The collision-time approximation widely used in dielectric crystals fails in molecular crystals for which the presence of slow relaxation times in the collision operator prevents the thermalization of the whole set of phonons and gives rise to an ultrasonic relaxation. Thus a more suitable approximation is suggested here, which leads to a new expression of the ultrasonic attenuation valid in molecular crystals. Different forms of this expression are discussed, and comparison with Liebermann's expression used in most of the previous papers shows that the present treatment takes better account of the anisotropy of the solid state. The fit of experimental results obtained for some ionic-molecular crystals also shows that the expression derived here gives better agreement than does Liebermann's. Finally, it is shown that in the framework of the present treatment and under rather general conditions, the anisotropy affects primarily the magnitude of the ultrasonic absorption due to the molecular relaxation, but it does not affect its frequency dependence.

  9. Sanger Sequencing for BRCA1 c.68_69del, BRCA1 c.5266dup and BRCA2 c.5946del Mutation Screen on Pap Smear Cytology Samples.

    PubMed

    Lee, Sin Hang; Zhou, Shaoxia; Zhou, Tianjun; Hong, Guofan

    2016-02-08

    Three sets of polymerase chain reaction (PCR) primers were designed for heminested PCR amplification of the target DNA fragments in the human genome which include the site of BRCA1 c.68_69del, BRCA1 c.5266dup and BRCA2 c.5946del respectively, to prepare the templates for direct Sanger sequencing screen of these three founder mutations. With a robust PCR mixture, crude proteinase K digestate of the fixed cervicovaginal cells in the liquid-based Papanicolaou (Pap) cytology specimens can be used as the sample for target DNA amplification without pre-PCR DNA extraction, purification and quantitation. The post-PCR products can be used directly as the sequencing templates without further purification or quantitation. By simplifying the frontend procedures for template preparation, the cost for screening these three founder mutations can be reduced to about US $200 per test when performed in conjunction with human papillomavirus (HPV) assays now routinely ordered for cervical cancer prevention. With this projected price structure, selective patients in a high-risk population can be tested and each provided with a set of DNA sequencing electropherograms to document the absence or presence of these founder mutations in her genome to help assess inherited susceptibility to breast and ovarian cancer in this era of precision molecular personalized medicine.

  10. [The scientific progress of the "Clinica del Lavoro Luigi Devoto" as seen through the contents of the journal "La Medicina del Lavoro". ].

    PubMed

    Foà, V; Camerino, Donatella

    2003-01-01

    On occasion of the Centenary of the "Clinica del Lavoro Luigi Devoto", its researchers suggested that awareness of its historical identity and scientific development should constitute the basis for the future of the Institution. The directors of the Institute who have succeeded one to the other over the years have left a vivid report of the vast amount of work developed in several research fields and also of the original results achieved with significant impact on the scientific community and on society. Content analysis of "La Medicina del Lavoro" allowed us to shed light on strong bonds existing between manufacturing techniques, work organization and health, in the different political and social periods in which they developed. Many actions have been defined and several research subjects have been renewed (according to current demands and new methodological possibilities) between the past and the present, nevertheless many new approaches need to be taken in the fields of epidemiology, indoor air quality, ergophthalmology, muskuloskeletal disorders, environmental and molecular toxicology, and further research will be undertaken thanks to the potential of this discipline for the future. The aim of this report is also to express our thanks to all the medical and non-medical staff who have made their contribution over 100 years of engagement.

  11. A Comparison of Molecular Vibrational Theory to Huckel Molecular Orbital Theory.

    ERIC Educational Resources Information Center

    Keeports, David

    1986-01-01

    Compares the similar mathematical problems of molecular vibrational calculations (at any intermediate level of sophistication) and molecular orbital calculations (at the Huckel level). Discusses how the generalizations of Huckel treatment of molecular orbitals apply to vibrational theory. (TW)

  12. EDITORIAL: Focus on Molecular Electronics FOCUS ON MOLECULAR ELECTRONICS

    NASA Astrophysics Data System (ADS)

    Scheer, Elke; Reineker, Peter

    2008-06-01

    The notion 'molecular electronics' has been used more frequently since the 1970s and summarizes a series of physical phenomena and ideas for their application in connection with organic molecules, oligomers, polymers, organic aggregates and solids. The properties studied in this field were connected to optical and electrical phenomena, such as optical absorption, fluorescence, nonlinear optics, energy transport, charge transfer, electrical conductance, and electron and nuclear spin-resonance. The final goal was and is to build devices which can compete or surpass some aspects of inorganic semiconductor devices. For example, on the basis of organic molecules there exist rectifiers, transistors, molecular wires, organic light emitting diodes, elements for photovoltaics, and displays. With respect to applications, one aspect of the organic materials is their broad variability and the lower effort and costs for their processability. The step from microstructures to the investigation of nanostructures is a big challenge also in this field and has lead to what nowadays is called molecular electronics in its narrow sense. In this field the subjects of the studies are often single molecules, e.g. single molecule optical spectroscopy, electrical conductance, i.e. charge transport through a single molecule, the influence of vibrational degrees of freedom, etc. A challenge here is to provide the techniques for addressing in a reproducible way the molecular scale. In another approach small molecular ensembles are studied in order to avoid artefacts from particular contact situations. The recent development of the field is presented in [1-8]. In this Focus Issue we present new results in the field of 'molecular electronics', both in its broad and specialized sense. One of the basic questions is the distribution of the energy levels responsible for optical absorption on the one hand and for the transport of charge on the other. A still unanswered question is whether the Wannier

  13. Nuevas observaciones de 3C10 con el VLA*: estudio de la expansión

    NASA Astrophysics Data System (ADS)

    Reynoso, E. M.; Moffett, D. A.:; Dubner, G. M.; Giacani, E. B.; Reynolds, S. P.; Goss, W. M.; Dickel, J.

    Se presentan nuevos resultados sobre la expansión del remanente de la supernova de Tycho a lo largo de un intervalo de 10.9 años, comparando nuevas observaciones tomadas con el VLA a 1375 y 1635 MHz durante 1994 y 1995, con observaciones previas realizadas entre 1983 y 1984 (Dickel y col. ~1991 AJ 101, 2151), usando las mismas configuraciones, anchos de banda, calibradores y tiempos de integración. El coeficiente de expansión se calcula para sectores radiales de 4o de ancho cada uno, ajustando la correlación cruzada de las derivadas de los perfiles promedio para cada época. A partir de la expansión medida, se estima el índice (parámetro de expansión) de la ley potencial R∝ tm como m≡ d ln R/d ln t . Este valor se compara con coeficientes teóricos para diferentes fases evolutivas de remanentes de supernova.

  14. Concepciones Alternativas de "Fotosintesis" en estudiantes Universitarios del curso basico de Biologia y posibles correcciones con el Modelo Educativo MODEF

    NASA Astrophysics Data System (ADS)

    De Jesus Roman, Sandra

    Concepciones Alternativas de Fotosíntesis en estudiantes Universitariosdel curso básico de Biología y posibles correcciones con el Modelo Educativo MODEF El modelo educativo para la enseñanza de Fotosíntesis (MODEF) se implantó para trabajar el problema de las concepciones alternativas (CA) en un curso de Biología General. Se evaluaron los resultados en cuanto al logro del aprendizaje significativo. La pregunta central de la investigación fue: ¿Cómo aporta el modelo educativo en la didáctica y comprensión del tema de fotosíntesis? Se efectuó una investigación acción con una fase cuantitativa y una cualitativa. Para la fase cuantitativa se elaboró una prueba para determinar las concepciones alternativas, se validó y se sometió a los estudiantes que participaron en el estudio antes y después de ofrecer la unidad de metabolismo celular. Los participantes eran estudiantes de primer año de la Universidad de Puerto Rico en Bayamón (UPRB). Se llevó a cabo un análisis de consistencia interna de la prueba mediante el método Alfa de Cronbach. Se analizaron las contestaciones a cada pregunta mediante la prueba de Ji cuadrado de contingencia, se efectuó la prueba de t y el coeficiente r de Pearson. La fase cualitativa incluyó la observación participativa de la investigadora- profesora, las reflexiones de los estudiantes y la información de las entrevistas semi-estructuradas que se realizaron a tres estudiantes del curso. El análisis se llevó a cabo mediante el Modelo de Wolcott. Se trabajaron diez CA de las cuales siete fueron corregidas mediante el Modelo MODEF. Las actividades más importantes para el proceso de aprendizaje incluyeron el trabajo de investigación o búsqueda de información para hacer una presentación digital, la elaboración de tablas, los mapas de conceptos, el uso de visuales o videos y las analogías para explicar conceptos o procesos. En conclusión: se recomienda el uso del Modelo MODEF para la discusión del tema de

  15. Nonlinear vibrational excitations in molecular crystals molecular mechanics calculations

    NASA Astrophysics Data System (ADS)

    Pumilia, P.; Abbate, S.; Baldini, G.; Ferro, D. R.; Tubino, R.

    1992-03-01

    The coupling constant for vibrational solitons χ has been examined in a molecular mechanics model for acetanilide (ACN) molecular crystal. According to A.C. Scott, solitons can form and propagate in solid acetanilide over a threshold energy value. This can be regarded as a structural model for the spines of hydrogen bond chains stabilizing the α helical structure of proteins. A one dimensional hydrogen bond chain of ACN has been built, for which we have found that, even though experimental parameters are correctly predicted, the excessive rigidity of the isolated chain prevents the formation of a localized distortion around the excitation. Yet, C=O coupling value with softer lattice modes could be rather high, allowing self-trapping to take place.

  16. Fragment Molecular Orbital Nonadiabatic Molecular Dynamics for Condensed Phase Systems.

    PubMed

    Nebgen, Ben; Prezhdo, Oleg V

    2016-09-15

    A method for efficiently simulating nonadiabatic molecular dynamics (NAMD) of nanoscale and condensed phase systems is developed and tested. The electronic structure, including force and nonadiabatic coupling, are obtained with the fragment molecular orbital (FMO) approximation, which provides significant computational savings by splitting the system into fragments and computing electronic properties of each fragment subject to the external field due to other all other fragments. The efficiency of the developed technique is demonstrated by studying the effect of explicit solvent molecules on excited state relaxation in the Fe(CO)4 complex. The relaxation in the gas phase occurs on a 50 fs time scale, which is in excellent agreement with previously recorded femtosecond pump-probe spectroscopy. Adding a solvation shell of ethanol molecules to the simulation results in an increase in the excited state lifetime to 100 fs, in agreement with recent femtosecond X-ray spectroscopy measurements.

  17. Available Instruments for Analyzing Molecular Dynamics Trajectories

    PubMed Central

    Likhachev, I. V.; Balabaev, N. K.; Galzitskaya, O. V.

    2016-01-01

    Molecular dynamics trajectories are the result of molecular dynamics simulations. Trajectories are sequential snapshots of simulated molecular system which represents atomic coordinates at specific time periods. Based on the definition, in a text format trajectory files are characterized by their simplicity and uselessness. To obtain information from such files, special programs and information processing techniques are applied: from molecular dynamics animation to finding characteristics along the trajectory (versus time). In this review, we describe different programs for processing molecular dynamics trajectories. The performance of these programs, usefulness for analyses of molecular dynamics trajectories, strong and weak aspects are discussed. PMID:27053964

  18. Molecular Modeling of Water Interfaces: From Molecular Spectroscopy to Thermodynamics.

    PubMed

    Nagata, Yuki; Ohto, Tatsuhiko; Backus, Ellen H G; Bonn, Mischa

    2016-04-28

    Understanding aqueous interfaces at the molecular level is not only fundamentally important, but also highly relevant for a variety of disciplines. For instance, electrode-water interfaces are relevant for electrochemistry, as are mineral-water interfaces for geochemistry and air-water interfaces for environmental chemistry; water-lipid interfaces constitute the boundaries of the cell membrane, and are thus relevant for biochemistry. One of the major challenges in these fields is to link macroscopic properties such as interfacial reactivity, solubility, and permeability as well as macroscopic thermodynamic and spectroscopic observables to the structure, structural changes, and dynamics of molecules at these interfaces. Simulations, by themselves, or in conjunction with appropriate experiments, can provide such molecular-level insights into aqueous interfaces. In this contribution, we review the current state-of-the-art of three levels of molecular dynamics (MD) simulation: ab initio, force field, and coarse-grained. We discuss the advantages, the potential, and the limitations of each approach for studying aqueous interfaces, by assessing computations of the sum-frequency generation spectra and surface tension. The comparison of experimental and simulation data provides information on the challenges of future MD simulations, such as improving the force field models and the van der Waals corrections in ab initio MD simulations. Once good agreement between experimental observables and simulation can be established, the simulation can be used to provide insights into the processes at a level of detail that is generally inaccessible to experiments. As an example we discuss the mechanism of the evaporation of water. We finish by presenting an outlook outlining four future challenges for molecular dynamics simulations of aqueous interfacial systems.

  19. Morphology, geology and geochemistry of the "Salar del Gran Bajo del Gualicho" (Rio Negro, Argentina)

    USGS Publications Warehouse

    Angelucci, A.; Barbieri, M.; Brodtkorb, A.; Ciccacci, S.; Civitelli, G.; De Barrio, R.; Di, Filippo M.; Fredi, P.; Friedman, I.; Lombardi, S.; Schalamuk, A.I.; Toro, B.

    1996-01-01

    A multidisciplinary study of the Gran Bajo del Gualicho area (Rio Negro - Argentina) was carried out; the aim was to delineate its geological and geomorphological evolution and to estabilish the genesis of salts filling the depression. Climatic conditions were analized first to individuate their role in the present morphogenetic processes; moreover the main morphological features of present landscape were examined as well as the stratigraphy of the outcropping formations, and of the Gran Bajo del Gualicho Formation in particular. Finally, a possible geomorphological evolution of the studied area was traced. Geophysical analyses allowed to estabilish that the paleosurface shaped on the crystalline basement is strongly uneven and shows evidence of the strong tectonic phases it underwent. The result of isotope analyses confirmed that the salt deposits on the Gran Bajo del Gualicho bottom were produced by fresh water evaporation, while strontium isotope ratio suggested that such waters were responsible for solubilization of more ancient evaporitic deposits.

  20. Propagation Modeling and Analysis of Molecular Motors in Molecular Communication.

    PubMed

    Chahibi, Youssef; Akyildiz, Ian F; Balasingham, Ilangko

    2016-10-24

    Molecular motor networks (MMNs) are networks constructed from molecular motors to enable nanomachines to perform coordinated tasks of sensing, computing, and actuation at the nano- and micro- scales. Living cells are naturally enabled with this same mechanism to establish point-to-point communication between different locations inside the cell. Similar to a railway system, the cytoplasm contains an intricate infrastructure of tracks, named microtubules, interconnecting different internal components of the cell. Motor proteins, such as kinesin and dynein, are able to travel along these tracks directionally, carrying with them large molecules that would otherwise be unreliably transported across the cytoplasm using free diffusion. Molecular communication has been previously proposed for the design and study of MMNs. However, the topological aspects of MMNs, including the effects of branches, have been ignored in the existing studies. In this paper, a physical end-to-end model for MMNs is developed, considering the location of the transmitter node, the network topology, and the receiver nodes. The end-to-end gain and group delay are considered as the performance measures, and analytical expressions for them are derived. The analytical model is validated by Monte-Carlo simulations and the performance of MMNs is analyzed numerically. It is shown that, depending on their nature and position, MMN nodes create impedance effects that are critical for the overall performance. This model could be applied to assist the design of artificial MMNs and to study cargo transport in neurofilaments to elucidate brain diseases related to microtubule jamming.

  1. Propagation Modeling and Analysis of Molecular Motors in Molecular Communication.

    PubMed

    Chahibi, Youssef; Akyildiz, Ian F; Balasingham, Ilangko

    2016-12-01

    Molecular motor networks (MMNs) are networks constructed from molecular motors to enable nanomachines to perform coordinated tasks of sensing, computing, and actuation at the nano- and micro- scales. Living cells are naturally enabled with this same mechanism to establish point-to-point communication between different locations inside the cell. Similar to a railway system, the cytoplasm contains an intricate infrastructure of tracks, named microtubules, interconnecting different internal components of the cell. Motor proteins, such as kinesin and dynein, are able to travel along these tracks directionally, carrying with them large molecules that would otherwise be unreliably transported across the cytoplasm using free diffusion. Molecular communication has been previously proposed for the design and study of MMNs. However, the topological aspects of MMNs, including the effects of branches, have been ignored in the existing studies. In this paper, a physical end-to-end model for MMNs is developed, considering the location of the transmitter node, the network topology, and the receiver nodes. The end-to-end gain and group delay are considered as the performance measures, and analytical expressions for them are derived. The analytical model is validated by Monte-Carlo simulations and the performance of MMNs is analyzed numerically. It is shown that, depending on their nature and position, MMN nodes create impedance effects that are critical for the overall performance. This model could be applied to assist the design of artificial MMNs and to study cargo transport in neurofilaments to elucidate brain diseases related to microtubule jamming.

  2. La estructura dinámica del cinturón de Kuiper interior y la formación de Urano y Neptuno

    NASA Astrophysics Data System (ADS)

    Melita, M. D.; Brunini, A.

    De acuerdo a los más recientes estudios sobre la formación de Urano y Neptuno, éstos podrían haber sufrido una importante migración radial hacia el exterior, debido al intercambio de momento angular con los planetesimales presentes en esa región durante las últimas etapas de la formación del Sistema Solar. Esta migración radial habría tenido importantes consecuencias sobre la presente estructura dinámica del cinturón cometario de Kuiper. Tal como lo reflejan las observaciones, la mayoría de los cuerpos observados en el cinturón de Kuiper se encuentran en resonancia de movimientos medios exteriores con Neptuno, hecho que también se refleja en la presente órbita de Plutón. En el presente trabajo se estudia tanto numérica como analíticamente la influencia de la variación de las masas de Urano y Neptuno durante el proceso de migración sobre las probabilidades de captura en algunas de las resonancias exteriores de Neptuno. Se estudia también la influencia de encuentros gravitacionales mutuos sobre la estabilidad de las órbitas resonantes. Este estudio ofrece argumentos de plausibilidad para explicar por qué ninguno de los objetos descubiertos en el cinturón de Kuiper se encontraría en la resonancia 2:1.

  3. Molecular robots with sensors and intelligence.

    PubMed

    Hagiya, Masami; Konagaya, Akihiko; Kobayashi, Satoshi; Saito, Hirohide; Murata, Satoshi

    2014-06-17

    CONSPECTUS: What we can call a molecular robot is a set of molecular devices such as sensors, logic gates, and actuators integrated into a consistent system. The molecular robot is supposed to react autonomously to its environment by receiving molecular signals and making decisions by molecular computation. Building such a system has long been a dream of scientists; however, despite extensive efforts, systems having all three functions (sensing, computation, and actuation) have not been realized yet. This Account introduces an ongoing research project that focuses on the development of molecular robotics funded by MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan). This 5 year project started in July 2012 and is titled "Development of Molecular Robots Equipped with Sensors and Intelligence". The major issues in the field of molecular robotics all correspond to a feedback (i.e., plan-do-see) cycle of a robotic system. More specifically, these issues are (1) developing molecular sensors capable of handling a wide array of signals, (2) developing amplification methods of signals to drive molecular computing devices, (3) accelerating molecular computing, (4) developing actuators that are controllable by molecular computers, and (5) providing bodies of molecular robots encapsulating the above molecular devices, which implement the conformational changes and locomotion of the robots. In this Account, the latest contributions to the project are reported. There are four research teams in the project that specialize on sensing, intelligence, amoeba-like actuation, and slime-like actuation, respectively. The molecular sensor team is focusing on the development of molecular sensors that can handle a variety of signals. This team is also investigating methods to amplify signals from the molecular sensors. The molecular intelligence team is developing molecular computers and is currently focusing on a new photochemical technology for accelerating DNA

  4. A molecular dawn for biogeochemistry

    USGS Publications Warehouse

    Zak, D.R.; Blackwood, C.B.; Waldrop, M.P.

    2006-01-01

    Biogeochemistry is at the dawn of an era in which molecular advances enable the discovery of novel microorganisms having unforeseen metabolic capabilities, revealing new insight into the underlying processes regulating elemental cycles at local to global scales. Traditionally, biogeochemical inquiry began by studying a process of interest, and then focusing downward to uncover the microorganisms and metabolic pathways mediating that process. With the ability to sequence functional genes from the environment, molecular approaches now enable the flow of inquiry in the opposite direction. Here, we argue that a focus on functional genes, the microorganisms in which they reside, and the interaction of those organisms with the broader microbial community could transform our understanding of many globally important biogeochemical processes. ?? 2006 Elsevier Ltd. All rights reserved.

  5. Proteomics, nanotechnology and molecular diagnostics.

    PubMed

    Johnson, Christopher J; Zhukovsky, Nikolay; Cass, Anthony E G; Nagy, Judit M

    2008-02-01

    Sequencing of the human genome opened the way to the exploration of the proteome and this has lead to the identification of large numbers of proteins in complex biological samples. The identification of diagnostic patterns in samples taken from patients to aid diagnosis is in the early stages of development. The solution to many of the technical challenges in proteomics and protein based molecular diagnostics will be found in new applications of nanomaterials. This review describes some of the physical and chemical principles underlying nanomaterials and devices and outlines how they can be used in proteomics; developments which are establishing nanoproteomics as a new field. Nanoproteomics will provide the platform for the discovery of next generation biomarkers. The field of molecular diagnostics will then come of age.

  6. Molecular biology of gastric cancer.

    PubMed

    Cervantes, A; Rodríguez Braun, E; Pérez Fidalgo, A; Chirivella González, I

    2007-04-01

    Despite its decreasing incidence overall, gastric cancer is still a challenging disease. Therapy is based mainly upon surgical resection when the tumour remains localised in the stomach. Conventional chemotherapy may play a role in treating micrometastatic disease and is effective as palliative therapy for recurrent or advanced disease. However, the knowledge of molecular pathways implicated in gastric cancer pathogenesis is still in its infancy and the contribution of molecular biology to the development of new targeted therapies in gastric cancer is far behind other more common cancers such as breast, colon or lung. This review will focus first on the difference of two well defined types of gastric cancer: intestinal and diffuse. A discussion of the cell of origin of gastric cancer with some intriguing data implicating bone marrow derived cells will follow, and a comprehensive review of different genetic alterations detected in gastric cancer, underlining those that may have clinical, therapeutic or prognostic implications.

  7. Visualization Software for Molecular Assemblies

    PubMed Central

    Goddard, Thomas D; Ferrin, Thomas E

    2007-01-01

    Summary Software for viewing three-dimensional models and maps of viruses, ribosomes, filaments and other molecular assemblies is advancing on many fronts. New developments include molecular representations that offer better control over level of detail, lighting that improves the perception of depth, and two-dimensional projections that simplify data interpretation. Programmable graphics processors offer quality, speed and visual effects not previously possible, while 3D printers, haptic interaction devices, and auto-stereo displays show promise in more naturally engaging our senses. Visualization methods are developed by diverse groups of researchers with differing goals: experimental biologists, database developers, computer scientists, and package developers. We survey recent developments and problems faced by the developer community in bringing innovative visualization methods into widespread use. PMID:17728125

  8. Molecular-specific urokinase antibodies

    NASA Technical Reports Server (NTRS)

    Atassi, M. Zouhair (Inventor); Morrison, Dennis R. (Inventor)

    2009-01-01

    Antibodies have been developed against the different molecular forms of urokinase using synthetic peptides as immunogens. The peptides were synthesized specifically to represent those regions of the urokinase molecules which are exposed in the three-dimensional configuration of the molecule and are uniquely homologous to urokinase. Antibodies are directed against the lysine 158-isoleucine 159 peptide bond which is cleaved during activation from the single-chain (ScuPA) form to the bioactive double chain (54 KDa and 33 KDa) forms of urokinase and against the lysine 135 lysine 136 bond that is cleaved in the process of removing the alpha-chain from the 54 KDa form to produce the 33 KDa form of urokinase. These antibodies enable the direct measurement of the different molecular forms of urokinase from small samples of conditioned medium harvested from cell cultures.

  9. Hierarchical analysis of molecular spectra

    SciTech Connect

    Davis, M.J.

    1996-03-01

    A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obtain any other way as well as an understanding of intramolecular energy transfer time scales, mechanisms, and pathways. The methodology has been applied to several problems: transition state spectroscopy, intramolecular energy transfer in highly excited molecules, high-resolution overtone spectroscopy, and the nature of the classical-quantum correspondence when there is classical chaos (``quantum chaos``).

  10. Molecular model for chirality phenomena.

    PubMed

    Latinwo, Folarin; Stillinger, Frank H; Debenedetti, Pablo G

    2016-10-21

    Chirality is a hallmark feature for molecular recognition in biology and chemical physics. We present a three-dimensional continuum model for studying chirality phenomena in condensed phases using molecular simulations. Our model system is based upon a simple four-site molecule and incorporates non-trivial kinetic behavior, including the ability to switch chirality or racemize, as well as thermodynamics arising from an energetic preference for specific chiral interactions. In particular, we introduce a chiral renormalization parameter that can locally favor either homochiral or heterochiral configurations. Using this model, we explore a range of chirality-specific phenomena, including the kinetics of chiral inversion, the mechanism of spontaneous chiral symmetry breaking in the liquid, chirally driven liquid-liquid phase separation, and chiral crystal structures.

  11. Molecular Recognition and Ligand Association

    NASA Astrophysics Data System (ADS)

    Baron, Riccardo; McCammon, J. Andrew

    2013-04-01

    We review recent developments in our understanding of molecular recognition and ligand association, focusing on two major viewpoints: (a) studies that highlight new physical insight into the molecular recognition process and the driving forces determining thermodynamic signatures of binding and (b) recent methodological advances in applications to protein-ligand binding. In particular, we highlight the challenges posed by compensating enthalpic and entropic terms, competing solute and solvent contributions, and the relevance of complex configurational ensembles comprising multiple protein, ligand, and solvent intermediate states. As more complete physics is taken into account, computational approaches increase their ability to complement experimental measurements, by providing a microscopic, dynamic view of ensemble-averaged experimental observables. Physics-based approaches are increasingly expanding their power in pharmacology applications.

  12. Molecular Imaging of Ovarian Cancer

    PubMed Central

    Sharma, Sai Kiran; Nemieboka, Brandon; Sala, Evis; Lewis, Jason S.; Zeglis, Brian M.

    2016-01-01

    Ovarian cancer is the most lethal gynecologic malignancy and the fifth leading cause of cancer-related death in women. Over the past decade, medical imaging has played an increasingly valuable role in the diagnosis, staging, and treatment planning of the disease. In this “Focus on Molecular Imaging” review, we seek to provide a brief yet informative survey of the current state of the molecular imaging of ovarian cancer. The article is divided into sections according to modality, covering recent advances in the MR, PET, SPECT, ultrasound, and optical imaging of ovarian cancer. Although primary emphasis is given to clinical studies, preclinical investigations that are particularly innovative and promising are discussed as well. Ultimately, we are hopeful that the combination of technologic innovations, novel imaging probes, and further integration of imaging into clinical protocols will lead to significant improvements in the survival rate for ovarian cancer. PMID:27127223

  13. Molecular etiology of idiopathic cardiomyopathy

    PubMed Central

    Arimura, T; Hayashi, T; Kimura, A

    2007-01-01

    Summary Idiopathic cardiomyopathy (ICM) is a primary cardiac disorder associated with abnormalities of ventricular wall thickness, size of ventricular cavity, contraction, relaxation, conduction and rhythm. Over the past two decades, molecular genetic analyses have revealed that mutations in the various genes cause ICM and such information concerning the genetic basis of ICM enables us to speculate the pathogenesis of this heterogeous cardiac disease. This review focuses on the molecular pathogenesis, i.e., genetic abnormalities and functional alterations due to the mutations especially in sarcomere/cytoskeletal components, in three characteristic features of ICM, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and restrictive cardiomyopathy (RCM). Understanding the functional abnormalities of the sarcomere/cytoskeletal components, in ICM, has unraveled the function of these components not only as a contractile unit but also as a pivot for transduction of biochemical signals. PMID:18646564

  14. Seebeck effect in molecular junctions.

    PubMed

    Zimbovskaya, Natalya A

    2016-05-11

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  15. Seebeck effect in molecular junctions

    NASA Astrophysics Data System (ADS)

    Zimbovskaya, Natalya A.

    2016-05-01

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  16. The evolution of molecular clouds

    NASA Technical Reports Server (NTRS)

    Shu, Frank H.; Lizano, Susana

    1988-01-01

    The problem of the structure and evolution of molecular clouds is reviewed, with particular emphasis given to the relationship with star formation. The basic hypothesis is that magnetic fields are the primary agents for supporting molecular clouds, although damped Alfven waves may play an important role in the direction parallel to the field lines. This picture naturally leads to a conception of 'bimodal star formation'. It is proposed that high-mass stars form from the overall gravitational collapse of a supercritical cloud, whereas low-mass stars form from small individual cores that slowly condense by ambipolar diffusion from a more extended envelope until they pass the brink of graviational instability and begin to collapse dynamically from 'inside-out'. The evidence that the infall stage of protostellar evolution is terminated by the development of a powerful stellar wind is reviewed.

  17. Variational Approach to Molecular Kinetics.

    PubMed

    Nüske, Feliks; Keller, Bettina G; Pérez-Hernández, Guillermo; Mey, Antonia S J S; Noé, Frank

    2014-04-08

    The eigenvalues and eigenvectors of the molecular dynamics propagator (or transfer operator) contain the essential information about the molecular thermodynamics and kinetics. This includes the stationary distribution, the metastable states, and state-to-state transition rates. Here, we present a variational approach for computing these dominant eigenvalues and eigenvectors. This approach is analogous to the variational approach used for computing stationary states in quantum mechanics. A corresponding method of linear variation is formulated. It is shown that the matrices needed for the linear variation method are correlation matrices that can be estimated from simple MD simulations for a given basis set. The method proposed here is thus to first define a basis set able to capture the relevant conformational transitions, then compute the respective correlation matrices, and then to compute their dominant eigenvalues and eigenvectors, thus obtaining the key ingredients of the slow kinetics.

  18. Carbon Nanotubes: Molecular Electronic Components

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1997-01-01

    The carbon Nanotube junctions have recently emerged as excellent candidates for use as the building blocks in the formation of nanoscale molecular electronic networks. While the simple joint of two dissimilar tubes can be generated by the introduction of a pair of heptagon-pentagon defects in an otherwise perfect hexagonal graphene sheet, more complex joints require other mechanisms. In this work we explore structural characteristics of complex 3-point junctions of carbon nanotubes using a generalized tight-binding molecular-dynamics scheme. The study of pi-electron local densities of states (LDOS) of these junctions reveal many interesting features, most prominent among them being the defect-induced states in the gap.

  19. Fluorescence applications in molecular neurobiology

    PubMed Central

    Taraska, Justin W.; Zagotta, William N.

    2012-01-01

    Summary Macromolecules drive the complex behavior of neurons. For example, channels and transporters control the movements of ions across membranes, SNAREs direct the fusion of vesicles at the synapse, and motors move cargo throughout the cell. Understanding the structure, assembly, and conformational movements of these and other neuronal proteins is essential to understanding the brain. Developments in fluorescence have allowed the architecture and dynamics of proteins to be studied in real time and in a cellular context with great accuracy. In this review, we cover classic and recent methods for studying protein structure, assembly, and dynamics with fluorescence. These methods include fluorescence and luminescence resonance energy transfer, single molecule bleaching analysis, intensity measurements, co-localization microscopy, electron transfer, and bi-molecular complementation analysis. We present the principles of these methods, highlight recent work that uses the methods, and discuss a framework for interpreting results as they apply to molecular neurobiology. PMID:20434995

  20. Molecular control of facial morphology

    PubMed Central

    Liu, B.; Rooker, S.M.; Helms, J.A.

    2010-01-01

    We present a developmental perspective on the concept of phylotypic and phenotypic stages of craniofacial development. Within Orders of avians and mammals, a phylotypic period exists when the morphology of the facial prominences is minimally divergent. We postulate that species-specific facial variations arise as a result of subtle shifts in the timing and the duration of molecular pathway activity (e.g., heterochrony), and present evidence demonstrating a critical role for Wnt and FGF signaling in this process. The same molecular pathways that shape the vertebrate face are also implicated in craniofacial deformities, indicating that comparisons between and among animal species may represent a novel method for the identification of human craniofacial disease genes. PMID:19747977