Science.gov

Sample records for estudio molecular del

  1. Preguntas y respuestas acerca del Estudio del

    Cancer.gov

    El Estudio del Tamoxifeno y Raloxifeno (STAR, por sus siglas en ingls) es un estudio clnico (un estudio de investigacin conducido con voluntarios) diseado para ver cómo el medicamento raloxifeno (Evista) se compara con el medicamento tamoxifeno (Nolvadex)

  2. Estudio fotométrico de emisiones moleculares del cometa Halley en la etapa de post-perihelio.

    NASA Astrophysics Data System (ADS)

    Sisteró, R. F.; Clariá, J. J.; Lapasset, E.

    Results from photoelectric photometry in molecular bands of comet Halley carried out at Bosque Alegre are presented. The largest emissions measured are those of molecules of C2, CN and C3 respectively.

  3. Síntesis: Resultados iniciales del Estudio Nacional de Ex

    Cancer.gov

    El 4 de noviembre de 2010, el Estudio Nacional de Exámenes de Pulmóndio a conocer resultados iniciales que indican que hubo 20% menos muertes por cáncer de pulmón entre los participantes del estudio evaluados con tomografía computarizada espiral de baja d

  4. 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.

  5. 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.

  6. 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.

  7. Se lanza Red Nacional de Estudios Clínicos del NCI

    Cancer.gov

    El Instituto Nacional del Cáncer (NCI) puso en marcha una nueva red de investigación de estudios clínicos con el objetivo de mejorar el tratamiento de más de 1,6 millones de estadounidenses que reciben un diagnóstico de cáncer cada año.

  8. 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

  9. 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

  10. 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.

  11. 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**.

  12. 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)

  13. Estudio del NCI revela que la obesidad extrema puede acortar la esperanza de vida hasta en 14 años

    Cancer.gov

    Los adultos con obesidad extrema tienen mayor riesgo de morir a edad más joven por cáncer y muchas otras causas entre ellas, enfermedades cardíacas, accidentes cerebrovasculares, diabetes y enfermedades del hígado y los riñones, según estudio del NCI.

  14. 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

  15. 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. PMID:25264397

  16. Resultados del Estudio Nacional de Colografía de Tomografía

    Cancer.gov

    Estudios anteriores encontraron que la colografía de tomografía computarizada, también conocida como colonoscopia virtual, era prometedora como método de examen selectivo de detección de cáncer colorrectal debido

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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.

  3. Estudio de Salud Agrícola

    Cancer.gov

    En 1993, científicos del Instituto Nacional del Cáncer, Instituto Nacional de Ciencias Ambientales y la Agencia de Protección Ambiental de Estados Unidos iniciaron un estudio conocido como Estudio de Salud Agrícola (AHS).

  4. Observaciones Fotometricas EN Bandas Moleculares del Cometa Halley

    NASA Astrophysics Data System (ADS)

    Claria, J. J.; Sistero, R. F.; Lapasset, E.

    1987-05-01

    Results from narrow-band photoelectric photometry of comet Halley after its perihelion passage are presented. The mean atmospheric extinction coefficients determined at Bosque Alegre for six bands between 3600 and 5200 Å are consistent with those of the UBV and DD0 systems. The largest fluxes measured successively correspond to the molecules of C2 , CN, and C3 . The CN emission is typically 70% of the one C2, while the one of C3 is about 20% . The observations show that : (i) There is no detectable contribution of molecular ions CO+ during the period in consideration. (ii) Between March 15 and 22 of 1986 there is a decrease in the proportion of molecules of C2,CN,andC3, with respect to the presence of dust indicate by the continuum. Similar decreases, observed with a P = 6d.1 ± 0d.2, coincide with disconnection events detected from Bosque Alegre and other observatories. If they correspond to the frequency of passage of magnetic solar sectors by the comet, a solar "synodic" rotation Pc = 4P = 24d.4±0d.8, with respect to the comet, is deduced. This value is in excellent agreement with the mean value of the apparent solar rotation with respect to the comet.

  5. 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.

  6. 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

  7. Molecular survey of hepatitis C virus in the touristic city of Mar del Plata, Argentina.

    PubMed

    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

  8. Screening for F508del as a first step in the molecular diagnosis of cystic fibrosis*,**

    PubMed Central

    Marson, Fernando Augusto de Lima; Bertuzzo, Carmen Silvia; Ribeiro, Maria Ângela Gonçalves de Oliveira; Ribeiro, Antônio Fernando; Ribeiro, José Dirceu

    2013-01-01

    OBJECTIVE: To determine the relevance of screening for the F508del mutation of the cystic fibrosis transmembrane conductance regulator gene as a first step in the genetic diagnosis of cystic fibrosis (CF) by associating the genotype with various clinical variables. METHODS: We evaluated 180 CF patients regarding the F508del mutation. The clinical data were obtained from the medical records of the patients and from interviews with their parents or legal guardians. RESULTS: Of the 180 patients studied, 65 (36.1%) did not carry the F508del mutation (group 0 [G0]), 67 (37.2%) were F508del heterozygous (G1), and 48 (26.7%) were F508del homozygous (G2). All three groups showed associations with the clinical variables. Homozygosis was associated with younger patients, younger age at CF diagnosis, and younger age at the first isolation of Pseudomonas aeruginosa (PA), as well as with higher prevalence of pancreatic insufficiency (PI) and non-mucoid PA (NMPA) colonization. In comparison with G1+G2 patients, G0 patients were older; first experienced clinical symptoms, digestive disease, and pulmonary disease at an older age; were older at CF diagnosis and at first PA isolation; and had a lower prevalence of PI and meconium ileus, as well as of colonization by NMPA, mucoid PA, and Burkholderia cepacia. In G1 patients, values were intermediate for age at CF diagnosis; age at first PA isolation, first pulmonary symptoms, and first clinical manifestations; MPA colonization; and OR for PI. CONCLUSIONS: The identification of F508del in 63.9% of the patients studied showed that this can be a useful tool as a first step in the genetic diagnosis of CF. The F508del genotype was associated with clinical severity of the disease, especially with the variables related to CF onset. PMID:23857699

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. Estudio Nacional de Exámenes de Pulmón: preguntas y respuestas

    Cancer.gov

    El Estudio Nacional de Exámenes de Pulmón (National Lung Screening Trial, NLST) es un estudio de exámenes selectivos de detección de cáncer de pulmón patrocinado por el Instituto Nacional del Cáncer (NCI) y llevado a cabo por la American College of Radiol

  14. 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

  15. Estudio de los Institutos Nacionales de la Salud indica que quienes toman café tienen un riesgo meno

    Cancer.gov

    Los adultos mayores que tomaron café, con o sin cafeína, tuvieron un riesgo menor de muerte en general que quienes no tomaron café, según un estudio llevado a cabo por investigadores del Instituto Nacional del Cáncer (NCI), parte de los Institutos Naciona

  16. 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.

  17. Resultados de estudio para cáncer de pulmón indica

    Cancer.gov

    El Instituto Nacional del Cáncer (NCI) da a conocer hoy resultados iniciales de un estudio de gran envergadura sobre métodos de detección para reducir el número de muertes por cáncer de pulmón al detectar cánceres en estadios relativamente iniciales.

  18. Integrated biophysical studies implicate partial unfolding of NBD1 of CFTR in the molecular pathogenesis of F508del cystic fibrosis.

    PubMed

    Wang, Chi; Protasevich, Irina; Yang, Zhengrong; Seehausen, Derek; Skalak, Timothy; Zhao, Xun; Atwell, Shane; Spencer Emtage, J; Wetmore, Diana R; Brouillette, Christie G; Hunt, John F

    2010-10-01

    The lethal genetic disease cystic fibrosis is caused predominantly by in-frame deletion of phenylalanine 508 in the cystic fibrosis transmembrane conductance regulator (CFTR). F508 is located in the first nucleotide-binding domain (NBD1) of CFTR, which functions as an ATP-gated chloride channel on the cell surface. The F508del mutation blocks CFTR export to the surface due to aberrant retention in the endoplasmic reticulum. While it was assumed that F508del interferes with NBD1 folding, biophysical studies of purified NBD1 have given conflicting results concerning the mutation's influence on domain folding and stability. We have conducted isothermal (this paper) and thermal (accompanying paper) denaturation studies of human NBD1 using a variety of biophysical techniques, including simultaneous circular dichroism, intrinsic fluorescence, and static light-scattering measurements. These studies show that, in the absence of ATP, NBD1 unfolds via two sequential conformational transitions. The first, which is strongly influenced by F508del, involves partial unfolding and leads to aggregation accompanied by an increase in tryptophan fluorescence. The second, which is not significantly influenced by F508del, involves full unfolding of NBD1. Mg-ATP binding delays the first transition, thereby offsetting the effect of F508del on domain stability. Evidence suggests that the initial partial unfolding transition is partially responsible for the poor in vitro solubility of human NBD1. Second-site mutations that increase the solubility of isolated F508del-NBD1 in vitro and suppress the trafficking defect of intact F508del-CFTR in vivo also stabilize the protein against this transition, supporting the hypothesize that it is responsible for the pathological trafficking of F508del-CFTR. PMID:20687163

  19. Integrated biophysical studies implicate partial unfolding of NBD1 of CFTR in the molecular pathogenesis of F508del cystic fibrosis

    PubMed Central

    Wang, Chi; Protasevich, Irina; Yang, Zhengrong; Seehausen, Derek; Skalak, Timothy; Zhao, Xun; Atwell, Shane; Spencer Emtage, J; Wetmore, Diana R; Brouillette, Christie G; Hunt, John F

    2010-01-01

    The lethal genetic disease cystic fibrosis is caused predominantly by in-frame deletion of phenylalanine 508 in the cystic fibrosis transmembrane conductance regulator (CFTR). F508 is located in the first nucleotide-binding domain (NBD1) of CFTR, which functions as an ATP-gated chloride channel on the cell surface. The F508del mutation blocks CFTR export to the surface due to aberrant retention in the endoplasmic reticulum. While it was assumed that F508del interferes with NBD1 folding, biophysical studies of purified NBD1 have given conflicting results concerning the mutation's influence on domain folding and stability. We have conducted isothermal (this paper) and thermal (accompanying paper) denaturation studies of human NBD1 using a variety of biophysical techniques, including simultaneous circular dichroism, intrinsic fluorescence, and static light-scattering measurements. These studies show that, in the absence of ATP, NBD1 unfolds via two sequential conformational transitions. The first, which is strongly influenced by F508del, involves partial unfolding and leads to aggregation accompanied by an increase in tryptophan fluorescence. The second, which is not significantly influenced by F508del, involves full unfolding of NBD1. Mg-ATP binding delays the first transition, thereby offsetting the effect of F508del on domain stability. Evidence suggests that the initial partial unfolding transition is partially responsible for the poor in vitro solubility of human NBD1. Second-site mutations that increase the solubility of isolated F508del-NBD1 in vitro and suppress the trafficking defect of intact F508del-CFTR in vivo also stabilize the protein against this transition, supporting the hypothesize that it is responsible for the pathological trafficking of F508del-CFTR. PMID:20687163

  20. Un estudio de los NIH indica que el consumo regular de aspirina podría reducir el riesgo de cáncer d

    Cancer.gov

    Las mujeres que toman aspirina diariamente podrían reducir el riesgo de cáncer de ovario en 20 por ciento, de acuerdo con un estudio realizado por científicos del Instituto Nacional del Cáncer (NCI), el cual forma parte de los Institutos Nacionales de la

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

    Cancer.gov

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

  2. 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.

  3. 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].

  4. 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 Central

    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

    2014-01-01

    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. PMID:25538099

  5. 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

    2015-02-01

    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. PMID:25538099

  6. 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.

  7. 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.

  8. Two molecular pathways (NMD and ERAD) contribute to a genetic epilepsy associated with the GABA(A) receptor GABRA1 PTC mutation, 975delC, S326fs328X.

    PubMed

    Kang, Jing-Qiong; Shen, Wangzhen; Macdonald, Robert L

    2009-03-01

    Approximately one-third of human genetic diseases are caused by premature translation-termination codon (PTC)-generating mutations. These mutations in sodium channel and GABA(A) receptor genes have been associated with idiopathic generalized epilepsies, but the cellular consequences of the PTCs on the mutant channel subunit biogenesis and function are unknown. The PTCs could result in translation of a truncated subunit, or more likely, trigger mRNA degradation through nonsense-mediated mRNA decay (NMD), thus preventing or reducing production of mutant subunit at the transcriptional level. The GABA(A) receptor alpha1 subunit mutation, 975delC, S326fs328X, is an autosomal dominant mutation associated with childhood absence epilepsy that generates a PTC in exon 8 of the 9 exon GABRA1 gene that is 74 bp upstream of intron 8. Using an intron 8-inclusion minigene that supports NMD, we demonstrated that mutant mRNA was substantially reduced, but not absent. Loss of mutant transcripts was blocked by ribosome inhibition or by silencing the NMD-essential gene hUPF-1. In both neurons and non-neuronal cells, the PTC caused substantial loss of mutant alpha1(S326fs328X) subunit mRNA through NMD with a minor portion of the mRNA escaping NMD and producing a mutant protein. The translated mutant protein had reduced stability due to endoplasmic reticulum associated degradation (ERAD) and had enhanced association with molecular chaperones. This study suggests that loss of mRNA due to activation of NMD and activation of ERAD by the mutant protein may contribute to epileptogenesis. The molecular mechanisms outlined here delineate a model for the pathogenesis of many PTC-generating mutations. PMID:19261879

  9. 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

  10. 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., (translator); 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.

  11. El NCI inicia un estudio para evaluar la utilidad de la secuenciación genética para mejorar los resu

    Cancer.gov

    El Instituto Nacional del Cáncer (NCI) lanzará este mes un estudio clínico piloto denominado M-PACT con la finalidad de evaluar si el tratamiento asignado según mutaciones genéticas específicas puede brindar beneficios a pacientes con tumores sólidos meta

  12. Resultado negativo de prueba del VPH es mejor predictor de riesgo bajo de cáncer de cuello uterino

    Cancer.gov

    De acuerdo con un estudio en el que participaron más de un millón de mujeres, los investigadores del NCI han determinado que el resultado negativo de una prueba para la detección del VPH proporciona mayor certeza o seguridad frente a riesgos futuros de cá

  13. 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.

  14. Clinical and laboratory update on the DEL variant.

    PubMed

    Nuchnoi, Pornlada; Thongbus, Jairak; Srisarin, Apapan; Kerdpin, Usanee; Prachayasittikul, Virapong

    2014-01-01

    Serological assays for the RhD blood group are based on detection of the RhD antigen on human red blood cells using a specific anti-D antibody. The weak expression of the RhD antigen in the DEL variant hinders the sensitivity of conventional serological assays. Evidence of anti-D immunization in patients with D-negativity who have received DEL-variant blood units has been reported in various populations. This observation has prompted the need for genetic epidemiological and clinical data on the DEL variant in the development of DEL molecular diagnostic testing. This review highlights the molecular features of the DEL variant, the clinical consequences of DEL-blood transfusion, and current approaches for detection of the DEL-variant for donor screening and transfusion. PMID:25316658

  15. 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

  16. Aspectos generales de los exámenes de detección del cáncer (PDQ®)—Versión para pacientes

    Cancer.gov

    Información sobre la medición de la eficacia de los exámenes de detección del cáncer y la evaluación de la solidez de las pruebas obtenidas en estudios de investigación de detección del cáncer.

  17. Aspectos generales de los exámenes de detección del cáncer (PDQ®)—Versión para profesionales de salud

    Cancer.gov

    Información sobre la medición de la eficacia de las pruebas de detección del cáncer y la evaluación de la solidez de las pruebas obtenidas en estudios de investigación de detección del cáncer.

  18. 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].

  19. Calcio y la prevención del cáncer

    Cancer.gov

    Hoja informativa que resume los resultados de estudios sobre el calcio y la prevención del cáncer. Incluye información sobre las recomendaciones dietéticas para calcio y la cantidad de calcio en los alimentos y en complementos de calcio.

  20. 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.

  1. [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.

  2. 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…

  3. 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.

  4. 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. PMID:27049633

  5. 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.

  6. 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

  7. Clinical and molecular genetic analysis of a Chinese family with congenital X-linked adrenal hypoplasia caused by novel mutation 1268delA in the DAX-1 gene*

    PubMed Central

    ZHANG, Zhe; FENG, Ye; YE, Dan; LI, Cheng-jiang; DONG, Feng-qin; TONG, Ying

    2015-01-01

    Congenital X-linked adrenal hypoplasia (AHC) is a rare disease characterized by primary adrenal insufficiency before adolescence and by hypogonadotropic hypogonadism (HHG) during adolescence. In this paper, we present a Chinese family with AHC. Two brothers, misdiagnosed with adrenal insufficiency of unknown etiology at the age of 9, were correctly diagnosed with AHC when delayed puberty, HHG, and testicular defects were observed. We investigated the clinical features and identified the dosage-sensitive sex reversal AHC critical region of the X chromosome gene 1 (DAX-1) mutation in this kindred. Direct sequencing of the DAX-1 gene revealed that the two siblings have a novel mutation (1268delA) of which their mother is a heterozygous carrier. This mutation causes a frameshift and a premature stop codon at position 436, encoding a truncated protein. It is important to increase knowledge of the mutational spectrum in genes related to this disease, linking phenotype to genotype. PMID:26537215

  8. Molecular dynamics

    SciTech Connect

    Ladd, A.J.C.

    1988-08-01

    The basic methodology of equilibrium molecular dynamics is described. Examples from the literature are used to illustrate how molecular dynamics has been used to resolve theoretical controversies, provide data to test theories, and occasionally to discover new phenomena. The emphasis is on the application of molecular dynamics to an understanding of the microscopic physics underlying the transport properties of simple fluids. 98 refs., 4 figs.

  9. 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.

  10. 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

  11. Molecular Haeckel.

    PubMed

    Elinson, Richard P; Kezmoh, Lorren

    2010-07-01

    More than a century ago, Ernst Haeckel created embryo drawings to illustrate the morphological similarity of vertebrate early embryos. These drawings have been both widely presented and frequently criticized. At the same time that the idea of morphological similarity was recently attacked, there has been a growing realization of molecular similarities in the development of tissues and organs. We have surveyed genes expressed in vertebrate embryos, and we have used them to construct drawings that we call Molecular Haeckels. The Molecular Haeckels emphasize that, based on gene expression, there is a greater similarity among vertebrate embryos than even Haeckel might have imagined. PMID:20549737

  12. "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.

  13. Molecular printing

    PubMed Central

    Braunschweig, Adam B.; Huo, Fengwei; Mirkin, Chad A.

    2014-01-01

    Molecular printing techniques, which involve the direct transfer of molecules to a substrate with submicrometre resolution, have been extensively developed over the past decade and have enabled many applications. Arrays of features on this scale have been used to direct materials assembly, in nanoelectronics, and as tools for genetic analysis and disease detection. The past decade has witnessed the maturation of molecular printing led by two synergistic technologies: dip-pen nanolithography and soft lithography. Both are characterized by material and substrate flexibility, but dip-pen nanolithography has unlimited pattern design whereas soft lithography has limited pattern flexibility but is low in cost and has high throughput. Advances in DPN tip arrays and inking methods have increased the throughput and enabled applications such as multiplexed arrays. A new approach to molecular printing, polymer-pen lithography, achieves low-cost, high-throughput and pattern flexibility. This Perspective discusses the evolution and future directions of molecular printing. PMID:21378889

  14. 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

  15. Molecular Spintronics using Molecular Nanomagnets

    NASA Astrophysics Data System (ADS)

    Wernsdorfer, Wolfgang

    2009-03-01

    A revolution in electronics is in view, with the contemporary evolution of two novel disciplines, spintronics and molecular electronics. A fundamental link between these two fields can be established using molecular magnetic materials and, in particular, single-molecule magnets [1], which combine the classic macroscale properties of a magnet with the quantum properties of a nanoscale entity. The resulting field, molecular spintronics aims at manipulating spins and charges in electronic devices containing one or more molecules. In this context, we want to fabricate, characterize and study molecular devices (molecular spin-transistor, molecular spin-valve and spin filter, molecular double-dot devices, carbon nanotube nano-SQUIDs, etc.) in order to read and manipulate the spin states of the molecule and to perform basic quantum operations. The talk will discuss this--still largely unexplored--field and present our the first important results [2,3].[4pt] [1] L. Bogani & W. Wernsdorfer, Nature Mat. 7, 179 (2008).[0pt] [2] J.-P. Cleuziou, W. Wernsdorfer, V. Bouchiat, T. Ondarcuhu, M. Monthioux, Nature Nanotech. 1, 53-59 (2006).[0pt] [3] N. Roch, S. Florens, V. Bouchiat, W. Wernsdorfer, F. Balestro, Nature 453, 633 (2008).

  16. 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.

  17. 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

  18. 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 Educational…

  19. Los NIH anuncian el lanzamiento de los estudios ALCHEMIST

    Cancer.gov

    Los Estudios sobre la Secuenciación e Identificación de Marcadores para el Mejoramiento de la Terapia Adjuvante para el Cáncer de Pulmón, ALCHEMIST, identificarán a pacientes con cáncer de pulmón en estadio inicial cuyos tumores tienen cambios genéticos.

  20. Cobertura de seguro y estudios clínicos

    Cancer.gov

    Información sobre los factores que las compañías de seguros médicos toman en cuenta a la hora de decidir si cubrirán los costos de los estudios clínicos y consejos para hacer gestiones con las compañías de seguros médicos.

  1. 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.

  2. 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

  3. Molecular Electronics

    NASA Astrophysics Data System (ADS)

    Petty, Michael

    The prospects of using organic materials in electronics and optoelectronics applications have attracted scientists and technologists since the 1970s. This field has become known as molecular electronics. Some successes have already been achieved, for example the liquid-crystal display. Other products such as organic light-emitting displays, chemical sensors and plastic transistors are developing fast. There is also a keen interest in exploiting technologies at the molecular scale that might eventually replace silicon devices. This chapter provides some of the background physics and chemistry to the interdisciplinary subject of molecular electronics. A review of some of the possible application areas for organic materials is presented and some speculation is provided regarding future directions.

  4. Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Wright, John D.

    1995-02-01

    This book describes the chemical and physical structure of molecular crystals, their optical and electronic properties, and the reactions between neighboring molecules in crystals. In the second edition, the author has taken into account research that has undergone extremely rapid development since the first edition was published in 1987. For instance, he gives extensive coverage to the applications of molecular materials in high-technology devices (e.g. optical communications, laser printers, photocopiers, liquid crystal displays, solar cells, and more). There is also an entirely new chapter on the recently discovered Buckminsterfullerene carbon molecule (C60) and organic non-linear optic materials.

  5. Il problema del litio.

    NASA Astrophysics Data System (ADS)

    D'Antona, F.

    1995-03-01

    Contents: 1. Introduzione. 2. La nucleosintesi del Big Bang. 3. Il litio nelle stelle di popolazione II. 4. I modelli stellari standard. 5. Il litio negli ammassi aperti. 6. Meccanismi di distruzione "non standard". 7. I modelli non-standard applicati alla popolazione II. 8. L'evoluzione Galattica del litio. 9. Quali stelle producono litio? 10. Il litio come elemento chiave per dare un nome agli oggetti stellari più minuscoli. 11. Conclusioni.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Molecular astrophysics

    NASA Astrophysics Data System (ADS)

    Herzberg, G.

    1989-01-01

    A brief history of Molecular Astrophysics is presented. The first molecules in space were identified in the 1920s in comets followed soon after by those in planetary atmospheres. The recent identification by MCKELLAR of the dimer of H 2, that is, (H 2) 2 in the atmosphere of Jupiter as well as the discovery, by DROSSART, MAILLARD, WATSON and others, of the H 3+ ion in the auroral zone of Jupiter are described. In this laboratory there is a continuing interest in interstellar molecules. Several molecules and molecular ions were observed by collaboration of laboratory spectroscopists and astronomers. Only the most recent ones are discussed. Also a few of the molecules not yet observed but likely to be observed are mentioned.

  11. 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

  12. 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.

  13. 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.

  14. 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

  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. 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

  17. Molecular clocks.

    PubMed

    Lee, Michael S Y; Ho, Simon Y W

    2016-05-23

    In the 1960s, several groups of scientists, including Emile Zuckerkandl and Linus Pauling, had noted that proteins experience amino acid replacements at a surprisingly consistent rate across very different species. This presumed single, uniform rate of genetic evolution was subsequently described using the term 'molecular clock'. Biologists quickly realised that such a universal pacemaker could be used as a yardstick for measuring the timescale of evolutionary divergences: estimating the rate of amino acid exchanges per unit of time and applying it to protein differences across a range of organisms would allow deduction of the divergence times of their respective lineages (Figure 1). PMID:27218841

  18. Molecular Mechanics

    PubMed Central

    Vanommeslaeghe, Kenno; Guvench, Olgun; MacKerell, Alexander D.

    2014-01-01

    Molecular Mechanics (MM) force fields are the methods of choice for protein simulations, which are essential in the study of conformational flexibility. Given the importance of protein flexibility in drug binding, MM is involved in most if not all Computational Structure-Based Drug Discovery (CSBDD) projects. This section introduces the reader to the fundamentals of MM, with a special emphasis on how the target data used in the parametrization of force fields determine their strengths and weaknesses. Variations and recent developments such as polarizable force fields are discussed. The section ends with a brief overview of common force fields in CSBDD. PMID:23947650

  19. Molecular replacement.

    PubMed

    Toth, Eric A

    2007-01-01

    As more protein structures are solved, the likelihood that current structural investigations will involve proteins for which there exists no homologous structure continually decreases. The extraction of phase information from diffraction experiments is one of several great barriers that crystallographers must overcome on the path to structure solution. One means to overcome this obstacle, the technique of molecular replacement, uses the structural similarity between proteins with similar sequences to give a good first estimate of the phases for the diffraction data of the protein of interest. The programs that execute this technique currently come in many flavors, from traditional Patterson-based methods, to stochastic searches in greater than three dimensions, to maximum likelihood-enhanced molecular replacement, each possessing unique advantages that can shake loose a recalcitrant solution. As crystallographers aim to solve larger macromolecular complexes that more faithfully depict the actors in cellular events, having existing phase information for parts of those biological machines will reinforce the technological advancements in data collection and structure solution that have already produced mammoth structures like the ribosome, yielding an ever-clearer picture of the inner workings of biology. PMID:17172763

  20. 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.

  1. 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

  2. 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; Juan Narbona); "The…

  3. 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.

  4. Qué tipos hay de estudios clínicos

    Cancer.gov

    Información sobre los diversos tipos de estudios clínicos de cáncer, como son los estudios de tratamiento, de prevención, de exámenes selectivos de detección, de cuidados médicos de apoyo y de cuidados paliativos.

  5. 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.

  6. 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.

  7. Atlas del Genoma del Cáncer: Antecedentes

    Cancer.gov

    El Atlas del Genoma del Cáncer es una iniciativa de los Institutos Nacionales de la Salud (NIH) para crear mapas multidimensionales completos de los cambios genómicos clave en los tipos y subtipos principales de cáncer.

  8. 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.

  9. Ácaros del mango

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Los ácaros constituyen un grupo abundante y diverso que ocupa diferentes hábitats en árboles frutales y la estructura y disposición del follaje y ramas del mango, contribuyen significativamente a que se presente gran diversidad de ácaros benéficos y dañinos asociados a esta especie frutal. En Colomb...

  10. 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.

  11. 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…

  12. 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.

  13. Study of apsidal motion in massive close binary systems. (Spanish Title: Estudio del movimiento apsidal en sistemas binarios masivos)

    NASA Astrophysics Data System (ADS)

    Ferrero, G.; Gamen, R.; Fernández-Lajús, E.

    In O+OB close binary systems, superior order momenta of the classical gravitational potential and general relativity effects produce a secular motion of the apsides. This phenomenon, together with theoretical stellar structure models, can be used to estimate the absolute masses of the system components, even for non-eclipsing binaries. We are conducting a spectroscopic study of eccentric close O+OB binaries in order to detect or confirm the existence of apsidal motion, determine its rate, and calculate the absolute masses of the stars. In this work we describe the current status of the project and present some preliminary results obtained for the systems iota Ori A, HD 93205, HD 152248, and HD 165052.

  14. Estudios interferométricos del campo magnético en regiones de formación estelar

    NASA Astrophysics Data System (ADS)

    Fernández López, M.; Stephens, I.; Segura-Cox, D.; Crutcher, R.; Looney, L. W.; Kwon, W.

    2015-08-01

    Currently, the possible role of magnetic fields in star formation processes is not clear. Despite the efforts made through single-dish observations, a stronger observational effort is required in order to broaden the sample of detections and acquire more insight into the morphology of the magnetic field at high-angular resolution scales. Here we present some results obtained from CARMA 1.25 mm continuum and spectral line polarization observations. The target of these observations were two accretion disks around a Class 0 (L1527) and a T Tauri (HL Tau) protostar and the massive star-forming region W3OH. We resolved the morphology of the magnetic field in both disks and, in W3OH, we achieved the first Zeeman detection ever made with an interferometer.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. [Progress in InDel as a new generation of genetic marker].

    PubMed

    Sun, Kuan; Zhang, Su-Hua; Zhu, Ru-Xin; Zhao, Shu-Min; Li, Cheng-Tao

    2013-04-01

    As forensic DNA typing experienced three generations of genetic marker researching stage, short tandem repeat (STR) has been widely used in forensic identification as a mature tool. Further exploration of the human genome led to the discovery of polymorphism markers of single nucleotide polymorphism (SNP) and Insertion/Deletion (InDel). InDel, which combines the desirable characteristics of previous genetic markers as a new type of genetic marker, has got extensive concern in fields like medical molecular biology and forensic biology. This paper generally reviews the history of research and the corresponding results of InDel along the line of time axis as well as the different aims of these research focusing on the progress in the multiple amplification system with several InDel as the genetic marker (autosomal or X chromosome) in forensic biology and anthropology. Finally, the direction of research in this field and the problems to be solved have been put forward. PMID:23930511

  20. 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

  1. 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.

  2. Progress in molecular SIMS

    SciTech Connect

    Borman, S.

    1987-04-15

    A review of sputtering and molecular ion emission is presented. New derivatization techniques have produced lower detection limits for molecular secondary ion mass spectrometry (SIMS). Spectra of representative organic compounds are presented.

  3. Se lanza Lung-MAP, el primer estudio de medicina de precisión de Red Nacional de Estudios Clínicos

    Cancer.gov

    Hoy se anunció el inicio de un estudio clínico denominado Protocolo Modelo para el Cáncer de Pulmón (Lung-MAP) en lo que constituye un esfuerzo de colaboración excepcional entre organizaciones públicas y privadas.

  4. Molecular electronics: Observation of molecular rectification

    SciTech Connect

    Waldeck, D.H.; Beratan, D.N. )

    1993-07-30

    The authors review some experiments in molecular rectification and their implication for commercial uses of molecular electronic devices. Two of the cases involve rectification by single molecules which consist of an electron donor on one side, an electron acceptor on the other side, and a bridge in between, coupled to electrodes. The third case involves rectification at a graphite electrode derivatized with a Cu phthalocyanine derivative, and probed with a Pt/Ir scanning tunneling microscope tip. Some potential applications of molecular devices are in high-density memory storage of holographic memory devices, neural networks, cellular automata, and chemical and biochemical sensors.

  5. Molecular Research in Aquaculture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular research and biotechnology have long been fields of study with applications useful to aquaculture and other animal sciences. Molecular Research in Aquaculture looks to provide an understanding of molecular research and its applications to the aquaculture industry in a format that allows in...

  6. Molecular Graphics and Chemistry.

    ERIC Educational Resources Information Center

    Weber, Jacques; And Others

    1992-01-01

    Explains molecular graphics, i.e., the application of computer graphics techniques to investigate molecular structure, function, and interaction. Structural models and molecular surfaces are discussed, and a theoretical model that can be used for the evaluation of intermolecular interaction energies for organometallics is described. (45…

  7. 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

  8. 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

  9. [Molecular epidemiology of cystic fibrosis in Tunisia].

    PubMed

    Messaoud, T; Bel Haj Fredj, S; Bibi, A; Elion, J; Férec, C; Fattoum, S

    2005-01-01

    Cystic fibrosis is the most frequent autosomal recessive genetic disease in North European population. This pathology seems to not be rare in Tunisia. On another hand, development of molecular biology techniques has largely contributed to implement the study of the different mutations in the CFTR gene where over 1,300 mutations were reported. Herein, we describe the strategy used to detect molecular defects responsible of cystic fibrosis on 390 children (383 families) in Tunisian population. Several techniques were performed for genotype diagnosis: DNA extraction was from peripheral blood. Polymerase chain reaction (PCR) and polyacylamide gel electrophoresis, and reverse dot blot procedures were used to detect known point mutations. Denaturant gradient gel electrophoresis (DGGE) were used in a next step searching for the unknown point mutations that are later identified by automated sequencing on ABIprism 310. This strategy allowed us to detect 17 different mutations located on the different exons of the CFTR gene. The most frequent was the F508del (50.74%) followed by three other mutations (G542X, W1282X and N1303K) known to be common in the Mediterranean area. For mutations (T665S, 2766 del8, F1166C, L1043R) were exclusively found, up to now, in the Tunisian population. Our results permitted to establish cystic fibrosis mutations and their distribution in Tunisia and to implement an appropriate prevention program of these diseases through the genetic council and prenatal diagnosis. PMID:16330381

  10. Molecular electrostatic potentials by systematic molecular fragmentation

    SciTech Connect

    Reid, David M.; Collins, Michael A.

    2013-11-14

    A simple method is presented for estimating the molecular electrostatic potential in and around molecules using systematic molecular fragmentation. This approach estimates the potential directly from the electron density. The accuracy of the method is established for a set of organic molecules and ions. The utility of the approach is demonstrated by estimating the binding energy of a water molecule in an internal cavity in the protein ubiquitin.

  11. 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.

  12. Standardized molecular typing.

    PubMed

    Müller, F M; Lischewski, A; Harmsen, D; Hacker, J

    1999-01-01

    Molecular typing methods are useful tools in molecular mycology. The results of these biotyping procedures may help to identify pathogenic strains in order to detect sources of nosocomial infection and for the investigation of epidemiological relationships. With respect to the facultative pathogen, Candida albicans, various methods such as pulse-field gel electrophoresis (PFGE), restriction fragment length polymorphism (RFLP), DNA fingerprinting methods and hybridization with repetitive DNA elements have been described as useful tools in molecular epidemiology. The previously described hybridization method with the Candida albicans specific CARE-2 probe and subsequent rehybridization with a molecular size marker is a standardized reproducible typing method for comparison of results obtained in different laboratories. In a larger epidemiological study conducted at the University Hospital of Würzburg analysing clinical C. albicans isolates, we were able to describe relationships between sequential patient isolates. These findings demonstrate that standardized molecular typing methods are a powerful tool in molecular mycology studies. PMID:10865907

  13. Atomic and molecular supernovae

    SciTech Connect

    Liu, W.

    1997-12-01

    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.

  14. 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.

  15. Vacunas contra los virus del papiloma humano

    Cancer.gov

    Una hoja informativa acerca de las vacunas contra los virus del papiloma humano (VPH) para prevenir infecciones con ciertos tipos de VPH, los cuales son la causa principal del cáncer de cuello del útero o cérvix.

  16. 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

  17. 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...

  18. Molecular Beacons in Diagnostics

    PubMed Central

    Kramer, Fred Russell

    2012-01-01

    Recent technical advances have begun to realize the potential of molecular beacons to test for diverse infections in clinical diagnostic laboratories. These include the ability to test for, and quantify, multiple pathogens in the same clinical sample, and to detect antibiotic resistant strains within hours. The design principles of molecular beacons have also spawned a variety of allied technologies. PMID:22619695

  19. Molecular biology of development

    SciTech Connect

    Davidson, E.H.; Firtel, R.A.

    1984-01-01

    This book is a compilation of papers presented at a symposium on the molecular biology of development. Topics discussed include: cytoplasmic localizations and pattern formations, gene expression during oogenesis and early development, developmental expression of gene families molecular aspects of plant development and transformation in whole organisms and cells.

  20. Estudios ALCHEMIST para el cáncer de pulmón en estadio inicial

    Cancer.gov

    ALCHEMIST comprende tres estudios clínicos integrados de medicina de precisión diseñados para identificar a personas con cáncer de pulmón en estadio inicial cuyos tumores tienen ciertos cambios genéticos poco comunes.

  1. Jóvenes con cáncer y supervivientes participan en estudio de oncofertilidad

    Cancer.gov

    Artículo sobre los esfuerzos que se realizan para conectar con pacientes jóvenes y lograr su participación en estudios clínicos para evaluar y remediar la esterilidad causada por el cáncer y su tratamiento.

  2. Molecular Characterization of β-Thalassemia Intermedia in Southeast Iran.

    PubMed

    Miri-Moghaddam, Ebrahim; Bahrami, Sara; Naderi, Majid; Bazi, Ali; Karimipoor, Morteza

    2016-06-01

    Inheritance of mild mutations within the β-globin gene and coinheritance of α-thalassemia (α-thal) are known as two important genetic modifiers in β-thalassemia (β-thal) intermedia (β-TI). We aimed to evaluate the spectrum of β- and α-thal mutations in β-TI patients in Southeast Iran. Common β- and α-globin gene mutations were detected by amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and multiplex gap-PCR, respectively. There were 26 male (57.8%) and 19 female (42.2%) patients. HBB: c.92 + 5T > C [IVS-I-5 (G > C)] and HBB: c.-138C + 1G > A [IVS-II-I (G > A)] represented the prevalent alleles with respective frequencies of 60.0 and 10.0%. Other β-globin mutations included HBB: c.-138C > T [-88 (C > T)], HBB: c.27_28insG [frameshift codons (FSC) 8/9 (+G)], HBB: c.46delT [codon 15 (-T)], HBB: c.93-22_95del (IVS-I, 25 del), and the 619 bp deletion (NG_000007.3: g.71609_72227del619). The predominant genotypic combinations were β(0)/β(0) (68.9%), β(0)/β(+ )(8.9%) and β(+)/β(+ )(2.2%). Coinheritance of α-thal was observed in 33.0% of the patients, with the -α(3.7) (rightward) (NG_000006.1: g.34164_37967del3804) as the most common deletion (86.0%). One patient was diagnosed with the -α(4.2) (leftward) (AF221717) and one with the - -(MED) (g.24664_41064del16401) deletions, while no patients carried the -(α)(20.5) (g.15164_37864del22701), α(-5 nt) (HBA2: c.95 + 2_95_6delTGAGG) or codon 19 (-G) (HBA2: c.56delG) mutations. The alleviating molecular mechanism was not explainable by β(+ )or concurrent α-thal in more than half of our β-TI patients. This encourages conducting more studies to identify other contributing factors, especially Hb F-inducing genetic modifiers. PMID:27117567

  3. 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.

  4. Fragment oriented molecular shapes.

    PubMed

    Hain, Ethan; Camacho, Carlos J; Koes, David Ryan

    2016-05-01

    Molecular shape is an important concept in drug design and virtual screening. Shape similarity typically uses either alignment methods, which dynamically optimize molecular poses with respect to the query molecular shape, or feature vector methods, which are computationally less demanding but less accurate. The computational cost of alignment can be reduced by pre-aligning shapes, as is done with the Volumetric-Aligned Molecular Shapes (VAMS) method. Here, we introduce and evaluate fragment oriented molecular shapes (FOMS), where shapes are aligned based on molecular fragments. FOMS enables the use of shape constraints, a novel method for precisely specifying molecular shape queries that provides the ability to perform partial shape matching and supports search algorithms that function on an interactive time scale. When evaluated using the challenging Maximum Unbiased Validation dataset, shape constraints were able to extract significantly enriched subsets of compounds for the majority of targets, and FOMS matched or exceeded the performance of both VAMS and an optimizing alignment method of shape similarity search. PMID:27085751

  5. Magnetomotive Molecular Nanoprobes

    PubMed Central

    John, Renu; Boppart, Stephen A.

    2012-01-01

    Tremendous developments in the field of biomedical imaging in the past two decades have resulted in the transformation of anatomical imaging to molecular-specific imaging. The main approaches towards imaging at a molecular level are the development of high resolution imaging modalities with high penetration depths and increased sensitivity, and the development of molecular probes with high specificity. The development of novel molecular contrast agents and their success in molecular optical imaging modalities have lead to the emergence of molecular optical imaging as a more versatile and capable technique for providing morphological, spatial, and functional information at the molecular level with high sensitivity and precision, compared to other imaging modalities. In this review, we discuss a new class of dynamic contrast agents called magnetomotive molecular nanoprobes for molecular-specific imaging. Magnetomotive agents are superparamagnetic nanoparticles, typically iron-oxide, that are physically displaced by the application of a small modulating external magnetic field. Dynamic phase-sensitive position measurements are performed using any high resolution imaging modality, including optical coherence tomography (OCT), ultrasonography, or magnetic resonance imaging (MRI). The dynamics of the magnetomotive agents can be used to extract the biomechanical tissue properties in which the nanoparticles are bound, and the agents can be used to deliver therapy via magnetomotive displacements to modulate or disrupt cell function, or hyperthermia to kill cells. These agents can be targeted via conjugation to antibodies, and in vivo targeted imaging has been shown in a carcinogen-induced rat mammary tumor model. The iron-oxide nanoparticles also exhibit negative T2 contrast in MRI, and modulations can produce ultrasound imaging contrast for multimodal imaging applications. PMID:21517766

  6. 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.

  7. Accelerated molecular dynamics methods

    SciTech Connect

    Perez, Danny

    2011-01-04

    The molecular dynamics method, although extremely powerful for materials simulations, is limited to times scales of roughly one microsecond or less. On longer time scales, dynamical evolution typically consists of infrequent events, which are usually activated processes. This course is focused on understanding infrequent-event dynamics, on methods for characterizing infrequent-event mechanisms and rate constants, and on methods for simulating long time scales in infrequent-event systems, emphasizing the recently developed accelerated molecular dynamics methods (hyperdynamics, parallel replica dynamics, and temperature accelerated dynamics). Some familiarity with basic statistical mechanics and molecular dynamics methods will be assumed.

  8. 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

  9. 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

  10. 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

  11. [Molecular diagnosis of mycobacteria].

    PubMed

    Kessler, Harald H

    2003-01-01

    Tuberculosis is one of the leading infectious diseases in the world. Using conventional methods, the isolation, identification, and drug susceptibility testing of Mycobacterium tuberculosis and other clinically important mycobacteria can take several weeks. During the past several years, molecular methods have been developed for direct detection, species identification, and drug susceptibility testing of mycobacteria. These methods can potentially reduce the diagnostic time from weeks to hours. For direct detection of Mycobacterium tuberculosis from clinical specimens, several molecular assays are commercially available today. They have been shown useful for the routine diagnostic laboratory. DNA probes and polymerase chain reaction-based sequencing have been widely used to identify mycobacterial species. Molecular methods have also been applied for the detection of mutations that confer drug resistance in mycobacteria. All in all, the future of clinical mycobacteriology appears to be heading toward direct detection, species identification and drug resistance determination using molecular methods. PMID:13677254

  12. 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.

  13. Molecular photoionization dynamics

    SciTech Connect

    Dehmer, Joseph L.

    1982-05-01

    This program seeks to develop both physical insight and quantitative characterization of molecular photoionization processes. Progress is briefly described, and some publications resulting from the research are listed. (WHK)

  14. Appendix II. Molecular Analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study of crop evolution, origins, and conservation entails the assessment of genetic variability with and between populations and species at different genetic, evolutionary, and taxonomic hierarchical levels. Molecular biology has greatly increased the amount of data and computational intensity...

  15. 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.

  16. 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)

  17. Ontologies for molecular biology.

    PubMed

    Schulze-Kremer, S

    1998-01-01

    Molecular biology has a communication problem. There are many databases using their own labels and categories for storing data objects and some using identical labels and categories but with a different meaning. A prominent example is the concept "gene" which is used with different semantics by major international genomic databases. Ontologies are one means to provide a semantic repository to systematically order relevant concepts in molecular biology and to bridge the different notions in various databases by explicitly specifying the meaning of and relation between the fundamental concepts in an application domain. Here, the upper level and a database branch of a prospective ontology for molecular biology (OMB) is presented and compared to other ontologies with respect to suitability for molecular biology (http:/(/)igd.rz-berlin.mpg.de/approximately www/oe/mbo.html). PMID:9697223

  18. 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.

  19. DelPhi: a comprehensive suite for DelPhi software and associated resources

    PubMed Central

    2012-01-01

    Background Accurate modeling of electrostatic potential and corresponding energies becomes increasingly important for understanding properties of biological macromolecules and their complexes. However, this is not an easy task due to the irregular shape of biological entities and the presence of water and mobile ions. Results Here we report a comprehensive suite for the well-known Poisson-Boltzmann solver, DelPhi, enriched with additional features to facilitate DelPhi usage. The suite allows for easy download of both DelPhi executable files and source code along with a makefile for local installations. The users can obtain the DelPhi manual and parameter files required for the corresponding investigation. Non-experienced researchers can download examples containing all necessary data to carry out DelPhi runs on a set of selected examples illustrating various DelPhi features and demonstrating DelPhi’s accuracy against analytical solutions. Conclusions DelPhi suite offers not only the DelPhi executable and sources files, examples and parameter files, but also provides links to third party developed resources either utilizing DelPhi or providing plugins for DelPhi. In addition, the users and developers are offered a forum to share ideas, resolve issues, report bugs and seek help with respect to the DelPhi package. The resource is available free of charge for academic users from URL: http://compbio.clemson.edu/DelPhi.php. PMID:22583952

  20. THE DARK MOLECULAR GAS

    SciTech Connect

    Wolfire, Mark G.; Hollenbach, David; McKee, Christopher F. E-mail: dhollenbach@seti.or

    2010-06-20

    The mass of molecular gas in an interstellar cloud is often measured using line emission from low rotational levels of CO, which are sensitive to the CO mass, and then scaling to the assumed molecular hydrogen H{sub 2} mass. However, a significant H{sub 2} mass may lie outside the CO region, in the outer regions of the molecular cloud where the gas-phase carbon resides in C or C{sup +}. Here, H{sub 2} self-shields or is shielded by dust from UV photodissociation, whereas CO is photodissociated. This H{sub 2} gas is 'dark' in molecular transitions because of the absence of CO and other trace molecules, and because H{sub 2} emits so weakly at temperatures 10 K molecular component. This component has been indirectly observed through other tracers of mass such as gamma rays produced in cosmic-ray collisions with the gas and far-infrared/submillimeter wavelength dust continuum radiation. In this paper, we theoretically model this dark mass and find that the fraction of the molecular mass in this dark component is remarkably constant ({approx}0.3 for average visual extinction through the cloud A-bar{sub V{approx_equal}}8) and insensitive to the incident ultraviolet radiation field strength, the internal density distribution, and the mass of the molecular cloud as long as A-bar{sub V}, or equivalently, the product of the average hydrogen nucleus column and the metallicity through the cloud, is constant. We also find that the dark mass fraction increases with decreasing A-bar{sub V}, since relatively more molecular H{sub 2} material lies outside the CO region in this case.

  1. 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.

  2. 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.

  3. 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.

  4. 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. PMID:26948350

  5. 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.

  6. Tierra del Fuego, Argentina, South America

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Mitre Peninsula is the easternmost tip of Tierra del Fuego, Argentina, (54.5S, 65.5W). Early winter snow can be seen on this south tip of the Andes Mountains. These same mountains continue underwater to Antarctica. The Strait of Magellan, separating the South American mainland from Tierra del Fuego is off the scene to the north and west, but the Strait of LeMaire, separating Tierra del Fuego from the Isla de los Estados can be seen.

  7. Artificial Molecular Machines.

    PubMed

    Balzani; Credi; Raymo; Stoddart

    2000-10-01

    The miniaturization of components used in the construction of working devices is being pursued currently by the large-downward (top-down) fabrication. This approach, however, which obliges solid-state physicists and electronic engineers to manipulate progressively smaller and smaller pieces of matter, has its intrinsic limitations. An alternative approach is a small-upward (bottom-up) one, starting from the smallest compositions of matter that have distinct shapes and unique properties-namely molecules. In the context of this particular challenge, chemists have been extending the concept of a macroscopic machine to the molecular level. A molecular-level machine can be defined as an assembly of a distinct number of molecular components that are designed to perform machinelike movements (output) as a result of an appropriate external stimulation (input). In common with their macroscopic counterparts, a molecular machine is characterized by 1) the kind of energy input supplied to make it work, 2) the nature of the movements of its component parts, 3) the way in which its operation can be monitored and controlled, 4) the ability to make it repeat its operation in a cyclic fashion, 5) the timescale needed to complete a full cycle of movements, and 6) the purpose of its operation. Undoubtedly, the best energy inputs to make molecular machines work are photons or electrons. Indeed, with appropriately chosen photochemically and electrochemically driven reactions, it is possible to design and synthesize molecular machines that do work. Moreover, the dramatic increase in our fundamental understanding of self-assembly and self-organizational processes in chemical synthesis has aided and abetted the construction of artificial molecular machines through the development of new methods of noncovalent synthesis and the emergence of supramolecular assistance to covalent synthesis as a uniquely powerful synthetic tool. The aim of this review is to present a unified view of the field

  8. 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

  9. Giant Molecular Magnetocapacitance

    SciTech Connect

    Wu, Yuning; Zhang, Xiaoguang; Cheng, Hai-Ping

    2013-01-01

    Capacitance of a nanoscale system is usually thought of having two contributions, a classical electrostatic contribution and a quantum contribution dependent on the density of states and/or molecular orbitals close to the Fermi energy. In this letter we demonstrate that in molecular nano-magnets and other magnetic nanoscale systems, the quantum part of the capacitance becomes spin-dependent, and is tunable by an external magnetic field. This molecular magnetocapacitance can be realized using single molecule nano-magnets and/or other nano-structures that have antiferromagnetic ground states. As a proof of principle, first-principles calculation of the nano-magnet [Mn3O(sao)3(O2CMe)(H2O)(py)3] shows that the charging energy of the high-spin state is 260 meV lower than that of the low-spin state, yielding a 6% difference in capacitance. A magnetic field of ~40T can switch the spin state, thus changing the molecular capacitance. A smaller switching field may be achieved using nanostructures with a larger moment. Molecular magnetocapacitance may lead to revolutionary device designs, e.g., by exploiting the Coulomb blockade magnetoresistance whereby a small change in capacitance can lead to a huge change in resistance.

  10. Cytogenetic and molecular abnormalities in chronic myelomonocytic leukemia

    PubMed Central

    Patnaik, M M; Tefferi, A

    2016-01-01

    Chronic myelomonocytic leukemia (CMML) is a clonal stem cell disorder associated with peripheral blood monocytosis and an inherent tendency to transform to acute myeloid leukemia. CMML has overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms. Clonal cytogenetic changes are seen in ~30%, whereas gene mutations are seen in >90% of patients. Common cytogenetic abnormalities include; trisomy 8, -Y, -7/del(7q), trisomy 21 and del(20q), with the Mayo–French risk stratification effectively risk stratifying patients based on cytogenetic abnormalities. Gene mutations frequently involve epigenetic regulators (TET2 ~60%), modulators of chromatin (ASXL1 ~40%), spliceosome components (SRSF2 ~50%), transcription factors (RUNX1 ~15%) and signal pathways (RAS ~30%, CBL ~15%). Of these, thus far, only nonsense and frameshift ASXL1 mutations have been shown to negatively impact overall survival. This has resulted in the development of contemporary, molecularly integrated (inclusive of ASXL1 mutations) CMML prognostic models, including Molecular Mayo Model and the Groupe Français des Myélodysplasies model. Better understanding of the prevalent genetic and epigenetic dysregulation has resulted in emerging targeted treatment options for some patients. The development of an integrated (cytogenetic and molecular) prognostic model along with CMML-specific response assessment criteria are much needed future goals. PMID:26849014

  11. Líneas Vitales: Programas y servicios del NCI

    Cancer.gov

    Artículos y videos sobre los programas y servicios del Instituto Nacional del Cáncer de la serie educativa Líneas Vitales del NCI, la cual está dirigida especialmente a poblaciones multiculturales.

  12. Control del cáncer y salud mundial: noticia del Instituto Nacional del Cáncer (NCI)

    Cancer.gov

    En combinación con una reunión de alto nivel de las Naciones Unidas sobre enfermedades no transmisibles en países en vías de desarrollo, el doctor Harold Varmus, director del NCI, y el doctor Ted L. Trimble, del NCI, han publicado un comentario en Science

  13. 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

  14. 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

  15. Primate molecular divergence dates.

    PubMed

    Steiper, Michael E; Young, Nathan M

    2006-11-01

    With genomic data, alignments can be assembled that greatly increase the number of informative sites for analysis of molecular divergence dates. Here, we present an estimate of the molecular divergence dates for all of the major primate groups. These date estimates are based on a Bayesian analysis of approximately 59.8 kbp of genomic data from 13 primates and 6 mammalian outgroups, using a range of paleontologically supported calibration estimates. Results support a Cretaceous last common ancestor of extant primates (approximately 77 mya), an Eocene divergence between platyrrhine and catarrhine primates (approximately 43 mya), an Oligocene origin of apes and Old World monkeys (approximately 31 mya), and an early Miocene (approximately 18 mya) divergence of Asian and African great apes. These dates are examined in the context of other molecular clock studies. PMID:16815047

  16. Molecular psychiatry of zebrafish.

    PubMed

    Stewart, A M; Ullmann, J F P; Norton, W H J; Parker, M O; Brennan, C H; Gerlai, R; Kalueff, A V

    2015-02-01

    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 central nervous system (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 molecular psychiatry research. PMID:25349164

  17. Porous Organic Molecular Materials

    SciTech Connect

    Tian, Jian; Thallapally, Praveen K.; McGrail, B. Peter

    2012-01-01

    Most nanoporous materials with molecular-scale pores are extended frameworks composed of directional covalent or coordination bonding, such as porous metal-organic frameworks and organic network polymers. By contrast, nanoporous materials comprised of discrete organic molecules, between which there are only weak non-covalent interactions, are seldom encountered. Indeed, most organic molecules pack efficiently in the solid state to minimize the void volume, leading to non-porous materials. In recent years, a significant number of nanoporous organic molecular materials, which may be either crystalline or amorphous, have been confirmed by the studies of gas adsorption and they are surveyed in this Highlight. In addition, the possible advantages of porous organic molecular materials over porous networks are discussed.

  18. 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

  19. Molecular subgroups of medulloblastoma

    PubMed Central

    Northcott, Paul A; Dubuc, Adrian M; Pfister, Stefan; Taylor, Michael D

    2014-01-01

    Recent efforts at stratifying medulloblastomas based on their molecular features have revolutionized our understanding of this morbidity. Collective efforts by multiple independent groups have subdivided medulloblastoma from a single disease into four distinct molecular subgroups characterized by disparate transcriptional signatures, mutational spectra, copy number profiles and, most importantly, clinical features. We present a summary of recent studies that have contributed to our understanding of the core medulloblastoma subgroups, focusing largely on clinically relevant discoveries that have already, and will continue to, shape research. PMID:22853794

  20. Molecular Umbrella Transport

    PubMed Central

    Mehiri, Mohamed; Chen, Wen-Hua; Janout, Vaclav; Regen, Steven L.

    2009-01-01

    The ability of a series of molecular umbrellas, derived from cholic acid, L-lysine, spermidine and Cascade Blue, to cross fluid liposomal membranes made from 1-palmitoyl-2-oleyol-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylglycerol (POPG) (95/5, mol/mol) has been determined. In sharp contrast to the clasic “size/lipophilicity” rule of membrane transport, those molecular umbrellas that were larger in size and less lipophilic crossed these liposomal membranes more readily. The likely origin for this unusual behavior is briefly discussed. PMID:19140686

  1. Circumstellar radio molecular lines

    NASA Technical Reports Server (NTRS)

    NGUYEN-QUANG-RIEU

    1987-01-01

    Radio molecular lines appear to be useful probes into the stellar environment. Silicon oxide masers provide information on the physical conditions in the immediate vicinity of the stellar photosphere. Valuable information on the physics operating in the envelope of IRC + 10216 was recently obtained by high sensitivity observations and detailed theoretical analyses. Infrared speckle interferometry in the molecular lines and in the continuum is helpful in the investigation of the inner region of the envelope. These techniques are discussed in terms of late-type star mass loss.

  2. Synthetic mechanochemical molecular swimmer.

    PubMed

    Golestanian, Ramin

    2010-07-01

    A minimal design for a molecular swimmer is proposed that is based on a mechanochemical propulsion mechanism. Conformational changes are induced by electrostatic actuation when specific parts of the molecule temporarily acquire net charges through catalyzed chemical reactions involving ionic components. The mechanochemical cycle is designed such that the resulting conformational changes would be sufficient for achieving low Reynolds number propulsion. The system is analyzed within the recently developed framework of stochastic swimmers to take account of the noisy environment at the molecular scale. The swimming velocity of the device is found to depend on the concentration of the fuel molecule according to the Michaelis-Menten rule in enzymatic reactions. PMID:20867483

  3. Molecular Pathology Informatics.

    PubMed

    Roy, Somak

    2015-06-01

    Molecular informatics (MI) is an evolving discipline that will support the dynamic landscape of molecular pathology and personalized medicine. MI provides a fertile ground for development of clinical solutions to bridge the gap between clinical informatics and bioinformatics. Rapid adoption of next generation sequencing (NGS) in the clinical arena has triggered major endeavors in MI that are expected to bring a paradigm shift in the practice of pathology. This brief review presents a broad overview of various aspects of MI, particularly in the context of NGS based testing. PMID:26065793

  4. 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.

  5. Molecular Engineering of DNA: Molecular Beacons

    PubMed Central

    Tang, Zhiwen; Yang, Chaoyong James; Kim, Youngmi; Fang, Xiaohong; Li, Wei; Wu, Yanrong; Medley, Colin D.; Cao, Zehui; Li, Jun; Colon, Patrick; Lin, Hui

    2009-01-01

    Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as fluorescent probes. Applications of MBs range from genetic screening, biosensor development, biochip construction, and the detection of single-nucleotide polymorphisms to mRNA monitoring in living cells. The inherent signal-transduction mechanism of MBs enables the analysis of target oligonucleotides without the separation of unbound probes. The MB stem–loop structure holds the fluorescence-donor and fluorescence-acceptor moieties in close proximity to one another, which results in resonant energy transfer. A spontaneous conformation change occurs upon hybridization to separate the two moieties and restore the fluorescence of the donor. Recent research has focused on the improvement of probe composition, intracellular gene quantitation, protein–DNA interaction studies, and protein recognition. PMID:19065690

  6. The Human 343delT HSPB5 Chaperone Associated with Early-onset Skeletal Myopathy Causes Defects in Protein Solubility.

    PubMed

    Mitzelfelt, Katie A; Limphong, Pattraranee; Choi, Melinda J; Kondrat, Frances D L; Lai, Shuping; Kolander, Kurt D; Kwok, Wai-Meng; Dai, Qiang; Grzybowski, Michael N; Zhang, Huali; Taylor, Graydon M; Lui, Qiang; Thao, Mai T; Hudson, Judith A; Barresi, Rita; Bushby, Kate; Jungbluth, Heinz; Wraige, Elizabeth; Geurts, Aron M; Benesch, Justin L P; Riedel, Michael; Christians, Elisabeth S; Minella, Alex C; Benjamin, Ivor J

    2016-07-15

    Mutations of HSPB5 (also known as CRYAB or αB-crystallin), a bona fide heat shock protein and molecular chaperone encoded by the HSPB5 (crystallin, alpha B) gene, are linked to multisystem disorders featuring variable combinations of cataracts, cardiomyopathy, and skeletal myopathy. This study aimed to investigate the pathological mechanisms involved in an early-onset myofibrillar myopathy manifesting in a child harboring a homozygous recessive mutation in HSPB5, 343delT. To study HSPB5 343delT protein dynamics, we utilize model cell culture systems including induced pluripotent stem cells derived from the 343delT patient (343delT/343delT) along with isogenic, heterozygous, gene-corrected control cells (WT KI/343delT) and BHK21 cells, a cell line lacking endogenous HSPB5 expression. 343delT/343delT and WT KI/343delT-induced pluripotent stem cell-derived skeletal myotubes and cardiomyocytes did not express detectable levels of 343delT protein, contributable to the extreme insolubility of the mutant protein. Overexpression of HSPB5 343delT resulted in insoluble mutant protein aggregates and induction of a cellular stress response. Co-expression of 343delT with WT prevented visible aggregation of 343delT and improved its solubility. Additionally, in vitro refolding of 343delT in the presence of WT rescued its solubility. We demonstrate an interaction between WT and 343delT both in vitro and within cells. These data support a loss-of-function model for the myopathy observed in the patient because the insoluble mutant would be unavailable to perform normal functions of HSPB5, although additional gain-of-function effects of the mutant protein cannot be excluded. Additionally, our data highlight the solubilization of 343delT by WT, concordant with the recessive inheritance of the disease and absence of symptoms in carrier individuals. PMID:27226619

  7. Instantánea del melanoma

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el melanoma; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  8. Instantánea del linfoma

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el linfoma; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  9. Instantánea del mieloma

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el mieloma; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  10. Instantánea del sarcoma

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el sarcoma; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  11. Biophysics of molecular gastronomy.

    PubMed

    Brenner, Michael P; Sörensen, Pia M

    2015-03-26

    Chefs and scientists exploring biophysical processes have given rise to molecular gastronomy. In this Commentary, we describe how a scientific understanding of recipes and techniques facilitates the development of new textures and expands the flavor palette. The new dishes that result engage our senses in unexpected ways. PAPERCLIP. PMID:25815978

  12. [Ortho-molecular nutrition].

    PubMed

    Martínez Bradshaw, Alejandro

    2005-03-01

    Ortho-molecular nutrition contemplates the deficiency of certain nutrients, not their deprivation, as the generator of short-term and long-term pathologies. By means of supplying these nutrients, an organism recovers. This method consists in building up an organism's functions by following the guides and indications provided by the organism itself. PMID:15871343

  13. 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.

  14. Atomic and Molecular Physics

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K.

    2005-01-01

    A symposium on atomic and molecular physics was held on November 18, 2005 at Goddard Space Flight Center. There were a number of talks through the day on various topics such as threshold law of ionization, scattering of electrons from atoms and molecules, muonic physics, positron physics, Rydberg states etc. The conference was attended by a number of physicists from all over the world.

  15. Molecular Detection of Sarcocystis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When people eat undercooked beef or pork containing viable Sarcocystis hominis or Sarcocystis suihominis, they can contract acute gastro-intestinal infections that culminate, about two weeks later, with the excretion of parasites infectious for cattle or swine, respectively. Molecular methods can p...

  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. Caroviologens: Towards molecular wires

    NASA Astrophysics Data System (ADS)

    Blanchard-Desce, M.; Arrhenius, T. S.; Dvolaïtzky, M.; Kugimiya, S.-I.; Lazrak, T.; Lehn, J.-M.

    1992-07-01

    Bispyridinium conjugated polyenes of different lengths and charges have been synthesized. Since they combine the features of carotenoids and of viologens, they have been termed caroviologens. Such molecules, possessing an extended conjugated chain fitted with polar electroactive endgroups, and having a length sufficient to span a lipid membrane could function as transmembrane electron channels, i.e., as molecular wires.

  19. 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…

  20. 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…

  1. Gymnastics of molecular chaperones.

    PubMed

    Mayer, Matthias P

    2010-08-13

    Molecular chaperones assist folding processes and conformational changes in many proteins. In order to do so, they progress through complex conformational cycles themselves. In this review, I discuss the diverse conformational dynamics of the ATP-dependent chaperones of the Hsp60, Hsp70, Hsp90, and Hsp100 families. PMID:20705236

  2. Molecular Stiffness of Selectins*

    PubMed Central

    Sarangapani, Krishna K.; Marshall, Bryan T.; McEver, Rodger P.; Zhu, Cheng

    2011-01-01

    During inflammation, selectin-ligand interactions provide forces for circulating leukocytes to adhere to vascular surfaces, which stretch the interacting molecules, suggesting that mechanical properties may be pertinent to their biological function. From mechanical measurements with atomic force microscopy, we analyzed the molecular characteristics of selectins complexed with ligands and antibodies. Respective stiffness of L-, E-, and P-selectins (4.2, 1.4, and 0.85 piconewton/nm) correlated inversely with the number (2, 6, and 9) of consensus repeats in the selectin structures that acted as springs in series to dominate their compliance. After reconstitution into a lipid bilayer, purified membrane P-selectin remained a dimer, capable of forming dimeric bonds with P-selectin glycoprotein ligand (PSGL)-1, endoglycan-Ig, and a dimeric form of a glycosulfopeptide modeled after the N terminus of PSGL-1. By comparison, purified membrane L- and E-selectin formed only monomeric bonds under identical conditions. Ligands and antibodies were much less stretchable than selectins. The length of endoglycan-Ig was found to be 51 ± 12 nm. These results provide a comprehensive characterization of the molecular stiffness of selectins and illustrate how mechanical measurements can be utilized for molecular analysis, e.g. evaluating the multimericity of selectins and determining the molecular length of endoglycan. PMID:21216951

  3. Soybean Molecular Genetic Diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A history of the various DNA marker types used in the assessment of molecular genetic diversity in soybean [Glycine max (L.) Merr.] is followed by a description of a number of studies on the assessment of genetic diversity. These studies include a review of reports on 1) the quantification and comp...

  4. 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)

  5. 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)

  6. 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.

  7. Molecular symmetry with quaternions.

    PubMed

    Fritzer, H P

    2001-09-01

    A new and relatively simple version of the quaternion calculus is offered which is especially suitable for applications in molecular symmetry and structure. After introducing the real quaternion algebra and its classical matrix representation in the group SO(4) the relations with vectors in 3-space and the connection with the rotation group SO(3) through automorphism properties of the algebra are discussed. The correlation of the unit quaternions with both the Cayley-Klein and the Euler parameters through the group SU(2) is presented. Besides rotations the extension of quaternions to other important symmetry operations, reflections and the spatial inversion, is given. Finally, the power of the quaternion calculus for molecular symmetry problems is revealed by treating some examples applied to icosahedral symmetry. PMID:11666072

  8. Carbyne: The Molecular Approach.

    PubMed

    Tykwinski, Rik R

    2015-12-01

    For the last 60+ years, the synthesis and study of cumulenes and polyynes have been the focus of a small, but dedicated, group of researchers. Many of the remarkable electronic, optical, and structural properties of cumulenes and polyynes had already been identified in the earliest reports. The molecular lengths achievable by the initial syntheses were, unfortunately, somewhat limited by synthetic methods available. For the past 15 years, we have worked toward expanding on the synthesis of cumulenes and polyynes through the development of new methods and stabilization motifs. As new compounds have become available, homologous series of cumulenes and polyynes have then been examined as a function of molecular length. While we are not yet there, we would like to eventually provide a general description of the sp-carbon allotrope carbyne, and this account presents some of our efforts toward this goal. PMID:26200096

  9. 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

  10. 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.

  11. Molecular inversion probe assay.

    PubMed

    Absalan, Farnaz; Ronaghi, Mostafa

    2007-01-01

    We have described molecular inversion probe technologies for large-scale genetic analyses. This technique provides a comprehensive and powerful tool for the analysis of genetic variation and enables affordable, large-scale studies that will help uncover the genetic basis of complex disease and explain the individual variation in response to therapeutics. Major applications of the molecular inversion probes (MIP) technologies include targeted genotyping from focused regions to whole-genome studies, and allele quantification of genomic rearrangements. The MIP technology (used in the HapMap project) provides an efficient, scalable, and affordable way to score polymorphisms in case/control populations for genetic studies. The MIP technology provides the highest commercially available multiplexing levels and assay conversion rates for targeted genotyping. This enables more informative, genome-wide studies with either the functional (direct detection) approach or the indirect detection approach. PMID:18025701

  12. Welding Molecular Crystals.

    PubMed

    Adolf, Cyril R R; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-12-16

    Both for fundamental and applied sciences, the design of complex molecular systems in the crystalline phase with strict control of order and periodicity at both microscopic and macroscopic levels is of prime importance for development of new solid-state materials and devices. The design and fabrication of complex crystalline systems as networks of crystals displaying task-specific properties is a step toward smart materials. Here we report on isostructural and almost isometric molecular crystals of different colors, their use for fabrication of core-shell crystals, and their welding by 3D epitaxial growth into networks of crystals as single-crystalline entities. Welding of crystals by self-assembly processes into macroscopic networks of crystals is a powerful strategy for the design of hierarchically organized periodic complex architectures composed of different subdomains displaying targeted characteristics. Crystal welding may be regarded as a first step toward the design of new hierarchically organized complex crystalline systems. PMID:26581391

  13. 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.

  14. An artificial molecular pump.

    PubMed

    Cheng, Chuyang; McGonigal, Paul R; Schneebeli, Severin T; Li, Hao; Vermeulen, Nicolaas A; Ke, Chenfeng; Stoddart, J Fraser

    2015-06-01

    Carrier proteins consume fuel in order to pump ions or molecules across cell membranes, creating concentration gradients. Their control over diffusion pathways, effected entirely through noncovalent bonding interactions, has inspired chemists to devise artificial systems that mimic their function. Here, we report a wholly artificial compound that acts on small molecules to create a gradient in their local concentration. It does so by using redox energy and precisely organized noncovalent bonding interactions to pump positively charged rings from solution and ensnare them around an oligomethylene chain, as part of a kinetically trapped entanglement. A redox-active viologen unit at the heart of a dumbbell-shaped molecular pump plays a dual role, first attracting and then repelling the rings during redox cycling, thereby enacting a flashing energy ratchet mechanism with a minimalistic design. Our artificial molecular pump performs work repetitively for two cycles of operation and drives rings away from equilibrium toward a higher local concentration. PMID:25984834

  15. Superposition State Molecular Dynamics.

    PubMed

    Venkatnathan, Arun; Voth, Gregory A

    2005-01-01

    The ergodic sampling of rough energy landscapes is crucial for understanding phenomena like protein folding, peptide aggregation, polymer dynamics, and the glass transition. These rough energy landscapes are characterized by the presence of many local minima separated by high energy barriers, where Molecular Dynamics (MD) fails to satisfy ergodicity. To enhance ergodic behavior, we have developed the Superposition State Molecular Dynamics (SSMD) method, which uses a superposition of energy states to obtain an effective potential for the MD simulation. In turn, the dynamics on this effective potential can be used to sample the configurational free energy of the real potential. The effectiveness of the SSMD method for a one-dimensional rough potential energy landscape is presented as a test case. PMID:26641113

  16. An artificial molecular pump

    NASA Astrophysics Data System (ADS)

    Cheng, Chuyang; McGonigal, Paul R.; Schneebeli, Severin T.; Li, Hao; Vermeulen, Nicolaas A.; Ke, Chenfeng; Stoddart, J. Fraser

    2015-06-01

    Carrier proteins consume fuel in order to pump ions or molecules across cell membranes, creating concentration gradients. Their control over diffusion pathways, effected entirely through noncovalent bonding interactions, has inspired chemists to devise artificial systems that mimic their function. Here, we report a wholly artificial compound that acts on small molecules to create a gradient in their local concentration. It does so by using redox energy and precisely organized noncovalent bonding interactions to pump positively charged rings from solution and ensnare them around an oligomethylene chain, as part of a kinetically trapped entanglement. A redox-active viologen unit at the heart of a dumbbell-shaped molecular pump plays a dual role, first attracting and then repelling the rings during redox cycling, thereby enacting a flashing energy ratchet mechanism with a minimalistic design. Our artificial molecular pump performs work repetitively for two cycles of operation and drives rings away from equilibrium toward a higher local concentration.

  17. 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

  18. Wholly Synthetic Molecular Machines.

    PubMed

    Cheng, Chuyang; Stoddart, J Fraser

    2016-06-17

    The past quarter of a century has witnessed an increasing engagement on the part of physicists and chemists in the design and synthesis of molecular machines de novo. This minireview traces the development of artificial molecular machines from their prototypes in the form of shuttles and switches to their emergence as motors and pumps where supplies of energy in the form of chemical fuel, electrochemical potential and light activation become a minimum requirement for them to function away from equilibrium. The challenge facing this rapidly growing community of scientists and engineers today is one of putting wholly synthetic molecules to work, both individually and as collections. Here, we highlight some of the recent conceptual and practical advances relating to the operation of wholly synthetic rotary and linear motors. PMID:26833859

  19. Molecular pathways in dystonia

    PubMed Central

    Bragg, D. Cristopher; Armata, Ioanna A.; Nery, Flavia C.; Breakefield, Xandra O.; Sharma, Nutan

    2011-01-01

    The hereditary dystonias comprise a set of diseases defined by a common constellation of motor deficits. These disorders are most likely associated with different molecular etiologies, many of which have yet to be elucidated. Here we discuss recent advances in three forms of hereditary dystonia, DYT1, DYT6 and DYT16, which share a similar clinical picture: onset in childhood or adolescence, progressive spread of symptoms with generalized involvement of body regions and a steady state affliction without treatment. Unlike DYT1, the genes responsible for DYT6 and DYT16 have only recently been identified, with relatively little information about the function of the encoded proteins. Nevertheless, recent data suggest that these proteins may fit together within interacting pathways involved in dopaminergic signaling, transcriptional regulation, and cellular stress responses. This review focuses on these molecular pathways, highlighting potential common themes among these dystonias which may serve as areas for future research. PMID:21134457

  20. Molecular water pumps.

    PubMed

    Zeuthen, T

    2000-01-01

    There is good evidence that cotransporters of the symport type behave as molecular water pumps, in which a water flux is coupled to the substrate fluxes. The free energy stored in the substrate gradients is utilized, by a mechanism within the protein, for the transport of water. Accordingly, the water flux is secondary active and can proceed uphill against the water chemical potential difference. The effect has been recognized in all symports studied so far (Table 1). It has been studied in details for the K+/Cl- cotransporter in the choroid plexus epithelium, the H+/lactate cotransporter in the retinal pigment epithelium, the intestinal Na+/glucose cotransporter (SGLT1) and the renal Na+/dicarboxylate cotransporter both expressed in Xenopus oocytes. The generality of the phenomenon among symports with widely different primary structures suggests that the property of molecular water pumps derives from a pattern of conformational changes common for this type of membrane proteins. Most of the data on molecular water pumps are derived from fluxes initiated by rapid changes in the composition of the external solution. There was no experimental evidence for unstirred layers in such experiments, in accordance with theoretical evaluations. Even the experimental introduction of unstirred layers did not lead to any measurable water fluxes. The majority of the experimental data supports a molecular model where water is cotransported: A well defined number of water molecules act as a substrate on equal footing with the non-aqueous substrates. The ratio of any two of the fluxes is constant, given by the properties of the protein, and is independent of the driving forces or other external parameters. The detailed mechanism behind the molecular water pumps is as yet unknown. It is, however, possible to combine well established phenomena for enzymes into a working model. For example, uptake and release of water is associated with conformational changes during enzymatic action; a

  1. Molecular Dynamics of Acetylcholinesterase

    SciTech Connect

    Shen, T Y.; Tai, Kaihsu; Henchman, Richard H.; Mccammon, Andy

    2002-06-01

    Molecular dynamics simulations are leading to a deeper understanding of the activity of the enzyme acetylcholinesterase. Simulations have shown how breathing motions in the enzyme facilitate the displacement of substrate from the surface of the enzyme to the buried active site. The most recent work points to the complex and spatially extensive nature of such motions and suggests possible modes of regulation of the activity of the enzyme.

  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. 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.

  4. MOLSCAT: MOLecular SCATtering

    NASA Astrophysics Data System (ADS)

    Hutson, Jeremy M.; Green, Sheldon

    2012-06-01

    MOLSCAT is a FORTRAN code for quantum mechanical (coupled channel) solution of the nonreactive molecular scattering problem and was developed to obtain collision rates for molecules in the interstellar gas which are needed to understand microwave and infrared astronomical observations. The code is implemented for various types of collision partners. In addition to the essentially exact close coupling method several approximate methods, including the Coupled States and Infinite Order Sudden approximations, are provided.

  5. Functional molecular ecological networks.

    PubMed

    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 CO(2) (eCO(2)) 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, CO(2) enrichment) experiment. Our results indicate that RMT is powerful in identifying functional molecular ecological networks in microbial communities. Both functional molecular ecological networks under eCO(2) and ambient CO(2) (aCO(2)) 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 eCO(2) and aCO(2), at the levels of the entire communities, individual functional gene categories/groups, and functional genes/sequences, suggesting that eCO(2) 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

  6. Moving beyond molecular mechanisms

    PubMed Central

    2015-01-01

    A major goal in cell biology is to bridge the gap in our understanding of how molecular mechanisms contribute to cell and organismal physiology. Approaches well established in the physical sciences could be instrumental in achieving this goal. A better integration of the physical sciences with cell biology will therefore be an important step in our quest to decipher how cells work together to construct a living organism. PMID:25601400

  7. Open boundary molecular dynamics

    NASA Astrophysics Data System (ADS)

    Delgado-Buscalioni, R.; Sablić, J.; Praprotnik, M.

    2015-09-01

    This contribution analyzes several strategies and combination of methodologies to perform molecular dynamic simulations in open systems. Here, the term open indicates that the total system has boundaries where transfer of mass, momentum and energy can take place. This formalism, which we call Open Boundary Molecular Dynamics (OBMD), can act as interface of different schemes, such as Adaptive Resolution Scheme (AdResS) and Hybrid continuum-particle dynamics to link atomistic, coarse-grained (CG) and continuum (Eulerian) fluid dynamics in the general framework of fluctuating Navier-Stokes equations. The core domain of the simulation box is solved using all-atom descriptions. The CG layer introduced using AdResS is located at the outer part of the open box to make feasible the insertion of large molecules into the system. Communications between the molecular system and the outer world are carried out in the outer layers, called buffers. These coupling preserve momentum and mass conservation laws and can thus be linked with Eulerian hydro- dynamic solvers. In its simpler form, OBMD allows, however, to impose a local pressure tensor and a heat flux across the system's boundaries. For a one component molecular system, the external normal pressure and temperature determine the external chemical potential and thus the independent parameters of a grand-canonical ensemble simulation. Extended ensembles under non-equilibrium stationary states can also be simulated as well as time dependent forcings (e.g. oscillatory rheology). To illustrate the robustness of the combined OBMD-AdResS method, we present simulations of star-polymer melts at equilibrium and in sheared flow.

  8. Communication: Molecular gears.

    PubMed

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

    2016-09-01

    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. PMID:27608981

  9. 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. PMID:24664921

  10. 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.

  11. Graphs in molecular biology

    PubMed Central

    Huber, Wolfgang; Carey, Vincent J; Long, Li; Falcon, Seth; Gentleman, Robert

    2007-01-01

    Graph theoretical concepts are useful for the description and analysis of interactions and relationships in biological systems. We give a brief introduction into some of the concepts and their areas of application in molecular biology. We discuss software that is available through the Bioconductor project and present a simple example application to the integration of a protein-protein interaction and a co-expression network. PMID:17903289

  12. 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

  13. Conceptual Considerations in Molecular Science

    ERIC Educational Resources Information Center

    Sawyer, Donald T.

    2005-01-01

    There are significant misconceptions within the chemical community and molecular science, particularly in the undergraduate curriculum and the associated textbooks. Some of the misconceptions are described, which give poor basis to understand molecular bonding and structure, and reaction mechanisms.

  14. Digitotalar dysmorphism: Molecular elucidation.

    PubMed

    Vorster, Anna Alvera; Beighton, Peter; Ramesar, Rajkumar Sewcharan

    2016-01-01

    Dominantly inherited digitotalar dysmorphism (DTD), which is characterised by flexion contractures of digits and 'rocker-bottom' feet due to a vertical talus, was first described in a South African family of European stock in 1972. We review the clinical manifestations and document the molecular basis for DTD in this prototype family. This family was restudied in 1995 and 2006 and biological specimens were obtained for molecular studies. Since the distal arthrogryposes (DAs) are genetically heterogeneous, an unbiased approach to mutation identification was undertaken through whole-exome next-generation sequencing of DNA from a single DTD-affected female. Venous blood specimens were obtained for DNA banking and subsequent molecular studies. Analysis of the nine genes that had previously been shown to cause DAs revealed a pathogenic mutation in exon nine of TNNT3. The presence of the p.(Arg63His) missense mutation at position 63 of TNNT3 was confirmed through direct cycle sequencing of genomic DNA in six affected family members for whom DNA had been archived. PMID:26915936

  15. Molecular Neuropathology of Gliomas

    PubMed Central

    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. PMID:19333441

  16. 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. PMID:25307570

  17. 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

  18. Molecular adsorption on graphene

    NASA Astrophysics Data System (ADS)

    Kong, Lingmei; Enders, Axel; Rahman, Talat S.; Dowben, Peter A.

    2014-11-01

    Current studies addressing the engineering of charge carrier concentration and the electronic band gap in epitaxial graphene using molecular adsorbates are reviewed. The focus here is on interactions between the graphene surface and the adsorbed molecules, including small gas molecules (H2O, H2, O2, CO, NO2, NO, and NH3), aromatic, and non-aromatic molecules (F4-TCNQ, PTCDA, TPA, Na-NH2, An-CH3, An-Br, Poly (ethylene imine) (PEI), and diazonium salts), and various biomolecules such as peptides, DNA fragments, and other derivatives. This is followed by a discussion on graphene-based gas sensor concepts. In reviewing the studies of the effects of molecular adsorption on graphene, it is evident that the strong manipulation of graphene’s electronic structure, including p- and n-doping, is not only possible with molecular adsorbates, but that this approach appears to be superior compared to these exploiting edge effects, local defects, or strain. However, graphene-based gas sensors, albeit feasible because huge adsorbate-induced variations in the relative conductivity are possible, generally suffer from the lack of chemical selectivity.

  19. Molecular adsorption on graphene.

    PubMed

    Kong, Lingmei; Enders, Axel; Rahman, Talat S; Dowben, Peter A

    2014-11-01

    Current studies addressing the engineering of charge carrier concentration and the electronic band gap in epitaxial graphene using molecular adsorbates are reviewed. The focus here is on interactions between the graphene surface and the adsorbed molecules, including small gas molecules (H(2)O, H(2), O(2), CO, NO(2), NO, and NH(3)), aromatic, and non-aromatic molecules (F4-TCNQ, PTCDA, TPA, Na-NH(2), An-CH(3), An-Br, Poly (ethylene imine) (PEI), and diazonium salts), and various biomolecules such as peptides, DNA fragments, and other derivatives. This is followed by a discussion on graphene-based gas sensor concepts. In reviewing the studies of the effects of molecular adsorption on graphene, it is evident that the strong manipulation of graphene's electronic structure, including p- and n-doping, is not only possible with molecular adsorbates, but that this approach appears to be superior compared to these exploiting edge effects, local defects, or strain. However, graphene-based gas sensors, albeit feasible because huge adsorbate-induced variations in the relative conductivity are possible, generally suffer from the lack of chemical selectivity. PMID:25287516

  20. 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. PMID:17303718

  1. 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

  2. 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 :

  3. 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

  4. Gonadal dysgenesis in del (18p) syndrome

    SciTech Connect

    Telvi, L.; Ion, A.; Fouquet, F.

    1995-07-17

    We report on a girl with syndromal gonadal dysgenesis and a de novo del (18p). Genetic factors controlling gonadal development are located not only on the X chromosome, but also on autosomes. The present case suggests that one of these genes is situated on 18p. We conclude that patients with del (18p) syndrome should be evaluated for gonadal dysgenesis. 16 refs., 3 figs.

  5. 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.

  6. 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. PMID:8744570

  7. 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. PMID:25284951

  8. 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

  9. Molecular ecological network analyses

    PubMed Central

    2012-01-01

    Background Understanding the interaction among different species within a community and their responses to environmental changes is a central goal in ecology. However, defining the network structure in a microbial community is very challenging due to their extremely high diversity and as-yet uncultivated status. Although recent advance of metagenomic technologies, such as high throughout sequencing and functional gene arrays, provide revolutionary tools for analyzing microbial community structure, it is still difficult to examine network interactions in a microbial community based on high-throughput metagenomics data. Results Here, we describe a novel mathematical and bioinformatics framework to construct ecological association networks named molecular ecological networks (MENs) through Random Matrix Theory (RMT)-based methods. Compared to other network construction methods, this approach is remarkable in that the network is automatically defined and robust to noise, thus providing excellent solutions to several common issues associated with high-throughput metagenomics data. We applied it to determine the network structure of microbial communities subjected to long-term experimental warming based on pyrosequencing data of 16 S rRNA genes. We showed that the constructed MENs under both warming and unwarming conditions exhibited topological features of scale free, small world and modularity, which were consistent with previously described molecular ecological networks. Eigengene analysis indicated that the eigengenes represented the module profiles relatively well. In consistency with many other studies, several major environmental traits including temperature and soil pH were found to be important in determining network interactions in the microbial communities examined. To facilitate its application by the scientific community, all these methods and statistical tools have been integrated into a comprehensive Molecular Ecological Network Analysis Pipeline (MENAP

  10. Molecular Mediators of Angiogenesis

    PubMed Central

    Ucuzian, Areck A.; Gassman, Andrew A.; East, Andrea T.; Greisler, Howard P.

    2010-01-01

    Angiogenesis, or the formation of new blood vessels from the preexisting vasculature, is a key component in numerous physiologic and pathologic responses and has broad impact in many medical and surgical specialties. In this review, we discuss the key cellular steps which lead to the neovascularization of tissues, and highlight the main molecular mechanisms and mediators in this process. We include discussions on proteolytic enzymes, cell/matrix interactions, pertinent cell signaling pathways, and end with a survey of the mechanisms which lead to the stabilization and maturation of neovasculatures. PMID:20061852

  11. Molecular biology and reproduction.

    PubMed

    McDonough, P G

    1999-03-01

    Modern molecular biology has provided unique insights into the fundamental understanding of reproductive disorders and the detection of microorganisms. The remarkable advances in DNA diagnostics have been expedited by the development of polymerase chain reaction (PCR) and the ability to isolate DNA and RNA from many different sources such as blood, saliva, hair roots, microscopic slides, paraffin-embedded tissue sections, clinical swabs, and even cancellous bone. These technical advances have been bolstered by the development of an increasing number of effective screening techniques to scan genomic DNA for unknown point mutations. The continued development of technology will ultimately result in automated DNA (desoxyribonucleic acid) diagnosis for the practicing clinician. The continuing expansion of information concerning the human genome will place an increasing emphasis on bioinformatics and the use of computer software for analyzing DNA sequences. With the automation of DNA diagnosis and the use of small samples (500 nanograms), the direct examination of the DNA of a patient, fetus, or microorganism will emerge as a definitive means of establishing the presence of the specific genetic change that causes disease. A knowledge of the precise pathology at the molecular level has and will provide important insights into the biochemical basis for many human diseases. A firm knowledge of the DNA alterations in disease and expression patterns of specific genes will provide for more directed therapeutic strategies. The refinement of vector technology and nuclear transplantion techniques will provide the opportunity for directed gene therapy to the early human embryo. This presentation is designed to acquaint the reader with current techniques of testing at the DNA level, prototype mutations in the reproductive sciences, new concepts in the molecular mechanisms of disease that affect reproduction, and therapeutic opportunities for the future. It is hoped that future

  12. Molecular mechanisms of epilepsy

    PubMed Central

    Staley, Kevin

    2015-01-01

    Decades of experimental work have established an imbalance of excitation and inhibition as the leading mechanism of the transition from normal brain function to seizure. In epilepsy, these transitions are rare and abrupt. Transition processes incorporating positive feedback, such as activity-dependent disinhibition, could provide these unique timing features. A rapidly expanding array of genetic etiologies will help delineate the molecular mechanism(s). This delineation will entail quite a bit of cell biology. The genes discovered to date are currently more remarkable for their diversity than their similarities. PMID:25710839

  13. 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.

  14. 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…

  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. 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…

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Multiscale reactive molecular dynamics

    PubMed Central

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

    2012-01-01

    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. PMID:23249062

  2. Towards graphyne molecular electronics.

    PubMed

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

    2015-01-01

    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. PMID:25699991

  3. 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.

  4. 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.

  5. Methods in Molecular Biophysics

    NASA Astrophysics Data System (ADS)

    Serdyuk, Igor N.; Zaccai, Nathan R.; Zaccai, Joseph

    2001-12-01

    Our knowledge of biological macromolecules and their interactions is based on the application of physical methods, ranging from classical thermodynamics to recently developed techniques for the detection and manipulation of single molecules. These methods, which include mass spectrometry, hydrodynamics, microscopy, diffraction and crystallography, electron microscopy, molecular dynamics simulations, and nuclear magnetic resonance, are complementary; each has its specific advantages and limitations. Organised by method, this textbook provides descriptions and examples of applications for the key physical methods in modern biology. It is an invaluable resource for undergraduate and graduate students of molecular biophysics in science and medical schools, as well as research scientists looking for an introduction to techniques beyond their specialty. As appropriate for this interdisciplinary field, the book includes short asides to explain physics aspects to biologists and biology aspects to physicists. Comprehensive coverage and up-to-date treatment of the latest physical methods in modern biology Each method includes a brief historical introduction, theoretical principles, applications, advantages and limitations, and concludes with a checklist of key ideas Interdisciplinary and accessible to biologists, physicists, and those with medical backgrounds

  6. 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).

  7. 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)

  8. Molecular basis of vaccination.

    PubMed

    Del Giudice, G; Pizza, M; Rappuoli, R

    1998-02-01

    Vaccines represent the most cost-effective means to prevent infectious diseases. Most of the vaccines which are currently available were developed long before the era of molecular biology and biotechnology. They were obtained following empirical approaches leading to the inactivation or to the attenuation of microorganisms, without any knowledge neither of the mechanisms of pathogenesis of the disease they were expected to protect from, nor of the immune responses elicited by the infectious agents or by the vaccine itself. The past two decades have seen an impressive progress in the field of immunology and molecular biology, which have allowed a better understanding of the interactions occurring between microbes and their hosts. This basic knowledge has represented an impetus towards the generation of better vaccines and the development of new vaccines. In this monograph we briefly summarize some of the most important biotechnological approaches that are currently followed in the development of new vaccines, and provide details on an approach to vaccine development: the genetic detoxification of bacterial toxins. Such an approach has been particularly successful in the rational design of a new vaccine against pertussis, which has been shown to be extremely efficacious and safe. It has been applied to the construction of powerful mucosal adjuvants, for administration of vaccines at mucosal surfaces. PMID:9789264

  9. 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

  10. 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. PMID:24860578

  11. 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…

  12. 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.

  13. Molecular modification of proanthocyanidins.

    PubMed

    Huo, Qing; Kong, Xiangye; Yang, Xiaofang; Wang, Yue; Ma, Lingling; Luo, Min; Xu, Diandou

    2016-07-01

    Regioselective enzymatic acylation of proanthocyanidin is proposed and investigated as a method by which to improve the solubility of proanthocyanidins in the oil phase and maintain its oxidation resistance. Experimental results indicate that butanol functions as the best solvent in the studied reaction, in which Lipase Novozym435 is used as biological catalyst enzyme and the molar ratio of lauric acid to proanthocyanidins is 4:1. To increase the esterification conversion, we propose the addition of molecular sieve at 5 h. The product was separated by TLC, and results indicate an optimal solvent ratio of ethyl acetate: petroleum ether: acetic acid = 2:3:0.5. This condition can effectively separate the ester and proanthocyanidins, achieving an esterification yield of 60.9%. PMID:27459598

  14. A molecular case report

    PubMed Central

    Kulesz-Martin, Molly; Lagowski, James; Olson, Susan; Wortham, Aaron; West, Toni; Thomas, George; Ryan, Christopher W.; Tyner, Jeffrey W.

    2013-01-01

    Current therapies for Renal Cell Carcinoma favor vascular endothelial growth factor receptor (VEGF-R) tyrosine kinase (TK) inhibitors (TKIs). In theory, these are most applicable in tumors that have lost VHL-with subsequent stabilization of HIF and upregulation of VEGF. A subset of patients harbor primary-refractory disease, as in this case, where there was no evidence for loss of VHL or chromosome 3p. We evaluated molecular targeted agents in viable tumor cells cultured from a patient’s clear cell renal cell carcinoma (RCC). Of 66 agents, only dasatinib, an inhibitor of Src tyrosine kinase, strongly reduced viability of the patient’s cultured kidney tumor cells. Immunostaining of the original primary tumor revealed strong positivity for VHL and Src protein expression. Functional evaluation of a patient’s tumor cells appears feasible in the setting of RCC. PMID:23192268

  15. 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. PMID:18246188

  16. Molecular genetics of alopecias.

    PubMed

    Ramot, Yuval; Zlotogorski, Abraham

    2015-01-01

    Recent developments in research methods and techniques, such as whole-exome and -genome sequencing, have substantially improved our understanding of genetic conditions. Special progress has been made in the field of genotrichoses, or hereditary hair diseases, a field that has been obscure for many years. The underlying genes for many of the monogenic hair diseases are now known. Additionally, complex analyses of large cohorts of patients have given us the first clues to the genes associated with polygenic hair disorders, such as androgenetic alopecia and alopecia areata. Thanks to these major findings, the sophisticated regulation of the morphogenesis, development and growth of hair follicles has begun to be revealed, and new players in this delicate molecular interplay have been exposed. PMID:26370647

  17. Molecular dynamics simulations

    SciTech Connect

    Alder, B.J.

    1985-07-01

    The molecular dynamics computer simulation discovery of the slow decay of the velocity autocorrelation function in fluids is briefly reviewed in order to contrast that long time tail with those observed for the stress autocorrelation function in fluids and the velocity autocorrelation function in the Lorentz gas. For a non-localized particle in the Lorentz gas it is made plausible that even if it behaved quantum mechanically its long time tail would be the same as the classical one. The generalization of Fick's law for diffusion for the Lorentz gas, necessary to avoid divergences due to the slow decay of correlations, is presented. For fluids, that generalization has not yet been established, but the region of validity of generalized hydrodynamics is discussed. 20 refs., 5 figs.

  18. Multiphotochromic molecular systems.

    PubMed

    Fihey, Arnaud; Perrier, Aurélie; Browne, Wesley R; Jacquemin, Denis

    2015-06-01

    Molecular systems encompassing more than one photochromic entity can be used to build highly functional materials, thanks to their potential multi-addressability and/or multi-response properties. Over the last decade, the synthesis and spectroscopic and kinetic characterisation as well as the modeling of a wide range of multiphotochromes have been achieved in a field that is emerging as a distinct branch of photochemistry. In this review, we provide an overview of the available multiphotochromic compounds which use a variety of photoactive building blocks, e.g., diarylethene, azobenzene, spiropyran, naphthopyran or fulgimide derivatives. Their efficiency in terms of multi-responsiveness is discussed and several strategies to circumvent the most common limitation (i.e., the loss of photochromism of one part) are described. PMID:25921433

  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. Gas Phase Molecular Dynamics

    SciTech Connect

    Hall, G.E.; Prrese, J.M.; Sears, T.J.; Weston, R.E.

    1999-05-21

    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 flee 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.

  1. 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

  2. Molecular probes for cardiovascular imaging.

    PubMed

    Liang, Grace; Nguyen, Patricia K

    2016-08-01

    Molecular probes provide imaging signal and contrast for the visualization, characterization, and measurement of biological processes at the molecular level. These probes can be designed to target the cell or tissue of interest and must be retained at the imaging site until they can be detected by the appropriate imaging modality. In this article, we will discuss the basic design of molecular probes, differences among the various types of probes, and general strategies for their evaluation of cardiovascular disease. PMID:27189171

  3. Time-resolved molecular imaging

    NASA Astrophysics Data System (ADS)

    Xu, Junliang; Blaga, Cosmin I.; Agostini, Pierre; DiMauro, Louis F.

    2016-06-01

    Time-resolved molecular imaging is a frontier of ultrafast optical science and physical chemistry. In this article, we review present and future key spectroscopic and microscopic techniques for ultrafast imaging of molecular dynamics and show their differences and connections. The advent of femtosecond lasers and free electron x-ray lasers bring us closer to this goal, which eventually will extend our knowledge about molecular dynamics to the attosecond time domain.

  4. 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.

  5. Molecular Hydrogen in Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Speck, Angela K.; Baldridge, Sean; Matsuura, Mikako

    2015-08-01

    Planetary Nebulae (PNe) have long played the role of laboratories for investigating atomic, molecular, dust and plasma physics, which have applications to diverse other astrophysical environments. In this presentation we will discuss clumpy structures within planetary nebulae that are the hosts to, and protectors of molecular gas in an otherwise forbidding ionized zone. We will present new observations of the molecular hydrogen emission from several PNe and discuss their implications for the formation, evolution and survival/demise of such molecular globules. The science behind dust and molecule formation and survival that apply to many other astronomical objects and places.

  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 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

  8. 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…

  9. From a single whole exome read to notions of clinical screening: primary ciliary dyskinesia and RSPH9 p.Lys268del in the Arabian Peninsula

    PubMed Central

    AlSaadi, Muslim M; Gaunt, Tom R; Boustred, Christopher R; Guthrie, Philip AI; Liu, Xuan; Lenzi, Luca; Rainbow, Lucille; Hall, Neil; Alharbi, Khalid K; Day, Ian NM

    2013-01-01

    SUMMARY Primary ciliary dyskinesia (PCD) is a genetic disorder, usually autosomal recessive, causing early respiratory disease and later subfertility. Whole exome sequencing may enable efficient analysis for locus heterogeneous disorders such as PCD. We whole exome sequenced one consanguineous Saudi Arabian with clinically diagnosed PCD and normal laterality, to attempt ab initio molecular diagnosis. We reviewed thirteen known PCD genes and potentially autozygous regions (extended homozygosity) for homozygous exon deletions, non-dbSNP codon, splice-site base variants or small indels. Homozygous non-dbSNP changes were also reviewed exome-wide. One single molecular read representing RSPH9 p.Lys268del was observed, with no wildtype reads, and a notable deficiency of mapped reads at this location. Among all observations, RSPH9 was the strongest candidate for causality. Searching unmapped reads revealed seven more mutant reads. Direct assay for p.Lys268del (MboII digest) confirmed homozygosity in the affected individual, then confirmed homozygosity in three siblings with bronchiectasis. Our finding in southwest Saudi Arabia indicates that p.Lys268del, previously observed in two Bedouin families (Israel, UAE) is geographically widespread in the Arabian Peninsula. Analogous with cystic fibrosis CFTR p.Phe508del, screening for RSPH9 p.Lys268del (which lacks sentinel dextrocardia) in those at risk would help in early diagnosis, tailored clinical management, genetic counselling and primary prevention. PMID:22384920

  10. Molecular digital pathology: progress and potential of exchanging molecular data.

    PubMed

    Roy, Somak; Pfeifer, John D; LaFramboise, William A; Pantanowitz, Liron

    2016-09-01

    Many of the demands to perform next generation sequencing (NGS) in the clinical laboratory can be resolved using the principles of telepathology. Molecular telepathology can allow facilities to outsource all or a portion of their NGS operation such as cloud computing, bioinformatics pipelines, variant data management, and knowledge curation. Clinical pathology laboratories can electronically share diverse types of molecular data with reference laboratories, technology service providers, and/or regulatory agencies. Exchange of electronic molecular data allows laboratories to perform validation of rare diseases using foreign data, check the accuracy of their test results against benchmarks, and leverage in silico proficiency testing. This review covers the emerging subject of molecular telepathology, describes clinical use cases for the appropriate exchange of molecular data, and highlights key issues such as data integrity, interoperable formats for massive genomic datasets, security, malpractice and emerging regulations involved with this novel practice. PMID:27471996

  11. 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…

  12. 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…

  13. Estudios de medicina de precisión para cáncer: empieza una nueva era

    Cancer.gov

    Avances en genómica, en exploraciones con imágenes, bioinformática y disciplinas relacionadas nos permiten diseñar estudios más pequeños, más rápidos y más inteligentes que incorporan los principios esenciales de la medicina de precisión.

  14. Molecular sensors for MEMS

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Yung

    Molecular sensors, known as pressure-sensitive paint and temperature-sensitive paint, are applied inside MEMS devices to obtain the internal and external flow fields. The spatial resolution for the PSP and TSP measurements has improved to 5 mum. The low-pressure PSP sensor has been investigated for use in MEMS measurements, with an application range from continuum flow to transition flow. PSP and TSP measurements in different micro devices have been obtained with the flow fields covering steady and unsteady, subsonic and supersonic flow. In microchannel measurements, the pressure distributions inside the microchannel have been obtained for Knudsen number from 0.006 to 0.8. Compressibility and rarefaction effects can be observed in the PSP data. Detailed information at the channel inlet was also collected to discuss the entrance effect for different flow regimes. For micronozzle experiments, four different micronozzles have been fabricated to study geometry effects at the micro scale. The pressure maps inside the micronozzle devices have been obtained with PSP sensors. A modified schlieren technique is used to compare the PSP results and investigate the shock wave behavior at high- and low-pressure conditions. Thick viscous layers in the micronozzle have been observed in the low-pressure measurements. For microjet impingements, heat transfer measurements have been collected with different microjet devices by using TSP sensors. For supersonic impinging microjet measurements, both pressure and temperature data have been obtained at different pressure ratios, impingement angles and impingement distances. Measurements reveal that the magnitude and number of shock cells decreases in the micro scale due to strong viscous effects. For microturbine measurements, averaged results of PSP and TSP measurements have been obtained for a rotation speed from 1300 to 4000 rpm. Phase-averaged results have been collected by using a laser triggering system at rotation speed of 1400 rpm

  15. 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.

  16. 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. PMID

  17. Molecular electronics under the microscope

    NASA Astrophysics Data System (ADS)

    2015-03-01

    The field of molecular electronics has developed significantly as experimental techniques to study charge transport through single molecules have become more reliable. Three Articles in this issue highlight how chemists can now better understand and control electronic properties at the molecular level.

  18. 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…

  19. 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)

  20. 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.

  1. Optically controllable molecular logic circuits

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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.

  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. 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.

  4. 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)

  5. Computationally Designed Molecularly Imprinted Materials

    NASA Astrophysics Data System (ADS)

    Pavel, Dumitru; Lagowski, Jolanta; Faid, Karim

    2004-03-01

    Molecular dynamics simulations were carried out for different molecular systems in order to predict the binding affinities, binding energies, binding distances and the active site groups between the simulated molecular systems and different bio-ligands (theophylline and its derivatives), which have been designed and minimized using molecular simulation techniques. The first simulated molecular systems consisted of a ligand and functional monomer, such as methacrylic acid and its derivatives. For each pair of molecular systems, (10 monomers with a ligand and 10 monomers without a ligand) a total energy difference was calculated in order to estimate the binding energy between a ligand and the corresponding monomers. The analysis of the simulated functional monomers with ligands indicates that the functional group of monomers interacting with ligands tends to be either COOH or CH2=CH. The distances between the ligand and monomer, in the most stable cases as indicated above, are between 2.0-4.5 Å. The second simulated molecular systems consisted of a ligand and a polymer. The polymers were obtained from monomers that were simulated above. And similar to monomer study, for each pair of molecular systems, (polymer with a ligand and polymer without a ligand) a total energy difference was calculated in order to estimate the binding energy between ligand and the corresponding polymer. The binding distance between the active site of a polymer and a ligand will also be discussed.

  6. Molecular imaging in ovarian cancer.

    PubMed

    Reyners, A K L; Broekman, K E; Glaudemans, A W J M; Brouwers, A H; Arts, H J G; van der Zee, A G J; de Vries, E G E; Jalving, M

    2016-04-01

    Ovarian cancer has a high mortality and novel-targeted treatment strategies have not resulted in breakthroughs for this disease. Insight into the molecular characteristics of ovarian tumors may improve diagnosis and selection of patients for treatment with targeted therapies. A potential way to achieve this is by means of molecular imaging. Generic tumor processes, such as glucose metabolism ((18)F-fluorodeoxyglucose) and DNA synthesis ((18)F-fluorodeoxythymidine), can be visualized non-invasively. More specific targets, such as hormone receptors, growth factor receptors, growth factors and targets of immunotherapy, can also be visualized. Molecular imaging can capture data on intra-patient tumor heterogeneity and is of potential value for individualized, target-guided treatment selection. Early changes in molecular characteristics during therapy may serve as early predictors of response. In this review, we describe the current knowledge on molecular imaging in the diagnosis and as an upfront or early predictive biomarker in patients with ovarian cancer. PMID:27141066

  7. 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

  8. 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. PMID:24600690

  9. Nucleic acid based molecular devices.

    PubMed

    Krishnan, Yamuna; Simmel, Friedrich C

    2011-03-28

    In biology, nucleic acids are carriers of molecular information: DNA's base sequence stores and imparts genetic instructions, while RNA's sequence plays the role of a messenger and a regulator of gene expression. As biopolymers, nucleic acids also have exciting physicochemical properties, which can be rationally influenced by the base sequence in myriad ways. Consequently, in recent years nucleic acids have also become important building blocks for bottom-up nanotechnology: as molecules for the self-assembly of molecular nanostructures and also as a material for building machinelike nanodevices. In this Review we will cover the most important developments in this growing field of nucleic acid nanodevices. We also provide an overview of the biochemical and biophysical background of this field and the major "historical" influences that shaped its development. Particular emphasis is laid on DNA molecular motors, molecular robotics, molecular information processing, and applications of nucleic acid nanodevices in biology. PMID:21432950

  10. Porphyrins as molecular nanomaterials

    NASA Astrophysics Data System (ADS)

    Faraon, Victor; Ion, Rodica-Mariana; Pop, Simona-Florentina; Van-Staden, Raluca; Van-Staden, Jacobus-Frederick

    2010-11-01

    Some pophyrins as molecular materials are discussed in this paper. Aggregates of these molecules have been known for some time to possess interesting properties. Their optical properties as isolated species in condensed phases have also recently become interesting, and their ability to form new hybrid materials, by mixing them with themselves or other molecules with different electron affinities and ionization potentials, now appears to be extremely attractive. Few porphyrin structures, 5,10,15,20-tetra-p-phenyl-porphyrin (TPP), 5,10,15,20-tetra-p-methoxy-phenyl-porphyrin (TMOPP), 5,10,15,20-tetra-p-tolyl-porphyrin (TTP), 5,10,15,20-tetra-p-sulphonato-phenyl-porphyrin (TSPP), have been synthesized in this paper. Some analytical investigations as UV-Vis spectrophotometry (UV-Vis), Fourier transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM) have been discussed as purity and stability criteria. Also, some considerations about their aggregation ability are discussed, and not in the last time, their capacity to generate porphyrin nanotubes.

  11. Molecular and Cellular Biophysics

    NASA Astrophysics Data System (ADS)

    Jackson, Meyer B.

    2006-01-01

    Molecular and Cellular Biophysics provides advanced undergraduate and graduate students with a foundation in the basic concepts of biophysics. Students who have taken physical chemistry and calculus courses will find this book an accessible and valuable aid in learning how these concepts can be used in biological research. The text provides a rigorous treatment of the fundamental theories in biophysics and illustrates their application with examples. Conformational transitions of proteins are studied first using thermodynamics, and subsequently with kinetics. Allosteric theory is developed as the synthesis of conformational transitions and association reactions. Basic ideas of thermodynamics and kinetics are applied to topics such as protein folding, enzyme catalysis and ion channel permeation. These concepts are then used as the building blocks in a treatment of membrane excitability. Through these examples, students will gain an understanding of the general importance and broad applicability of biophysical principles to biological problems. Offers a unique synthesis of concepts across a wide range of biophysical topics Provides a rigorous theoretical treatment, alongside applications in biological systems Author has been teaching biophysics for nearly 25 years

  12. Similarity of molecular shape.

    PubMed

    Meyer, A Y; Richards, W G

    1991-10-01

    The similarity of one molecule to another has usually been defined in terms of electron densities or electrostatic potentials or fields. Here it is expressed as a function of the molecular shape. Formulations of similarity (S) reduce to very simple forms, thus rendering the computerised calculation straightforward and fast. 'Elements of similarity' are identified, in the same spirit as 'elements of chirality', except that the former are understood to be variable rather than present-or-absent. Methods are presented which bypass the time-consuming mathematical optimisation of the relative orientation of the molecules. Numerical results are presented and examined, with emphasis on the similarity of isomers. At the extreme, enantiomeric pairs are considered, where it is the dissimilarity (D = 1 - S) that is of consequence. We argue that chiral molecules can be graded by dissimilarity, and show that D is the shape-analog of the 'chirality coefficient', with the simple form of the former opening up numerical access to the latter. PMID:1770379

  13. Molecular mechanisms of cancer.

    PubMed Central

    Koeffler, H. P.; McCormick, F.; Denny, C.

    1991-01-01

    Cancer is caused by specific DNA damage. Several common mechanisms that cause DNA damage result in specific malignant disorders: First, proto-oncogenes can be activated by translocations. For example, translocation of the c-myc proto-oncogene from chromosome 8 to one of the immunoglobulin loci on chromosomes 2, 14, or 22 results in Burkitt's lymphomas. Translocation of the c-abl proto-oncogene from chromosome 9 to the BCR gene located on chromosome 22 produces a hybrid BCR/ABL protein resulting in chronic myelogenous leukemia. Second, proto-oncogenes can be activated by point mutations. For example, point mutations of genes coding for guanosine triphosphate-binding proteins, such as H-, K-, or N-ras or G proteins, can be oncogenic as noted in a large variety of malignant neoplasms. Proteins from these mutated genes are constitutively active rather than being faithful second messengers of periodic extracellular signals. Third, mutations that inactivate a gene can result in tumors if the product of the gene normally constrains cellular proliferation. Functional loss of these "tumor suppressor genes" is found in many tumors such as colon and lung cancers. The diagnosis, classification, and treatment of cancers will be greatly enhanced by understanding their abnormalities at the molecular level. PMID:1815390

  14. 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}.

  15. MOLECULAR MECHANISMS OF PREECLAMPSIA

    PubMed Central

    Mutter, Walter P.; Karumanchi, S. Ananth

    2008-01-01

    Preeclampsia is a major cause of maternal, fetal, and neonatal mortality worldwide. The mechanisms that initiate preeclampsia in humans have been elusive, but some parts of the puzzle have begun to come together. A key discovery in the field was the realization that its major phenotypes, such as hypertension and proteinuria, are due to excess circulating soluble fms-like tyrosine kinase-1 (sFlt-1, also referred to as sVEGFR-1). sFlt-1 is an endogenous anti-angiogenic protein that is made by the placenta and acts by neutralizing the pro-angiogenic proteins vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). More recently, soluble endoglin, another circulating anti-angiogenic protein was found to synergize with sFlt1 and contribute to the pathogenesis of preeclampsia. Abnormalities in these circulating angiogenic proteins are not only present during clinical preeclampsia, but also antedate clinical symptoms by several weeks. This review will summarize our current understanding of the molecular mechanism of preeclampsia, with an emphasis on the recently characterized circulating anti-angiogenic proteins. PMID:17553534

  16. 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.

  17. Designing the molecular future.

    PubMed

    Schneider, Gisbert

    2012-01-01

    Approximately 25 years ago the first computer applications were conceived for the purpose of automated 'de novo' drug design, prominent pioneering tools being ALADDIN, CAVEAT, GENOA, and DYLOMMS. Many of these early concepts were enabled by innovative techniques for ligand-receptor interaction modeling like GRID, MCSS, DOCK, and CoMFA, which still provide the theoretical framework for several more recently developed molecular design algorithms. After a first wave of software tools and groundbreaking applications in the 1990s--expressly GROW, GrowMol, LEGEND, and LUDI representing some of the key players--we are currently witnessing a renewed strong interest in this field. Innovative ideas for both receptor and ligand-based drug design have recently been published. We here provide a personal perspective on the evolution of de novo design, highlighting some of the historic achievements as well as possible future developments of this exciting field of research, which combines multiple scientific disciplines and is, like few other areas in chemistry, subject to continuous enthusiastic discussion and compassionate dispute. PMID:22127731

  18. Molecular genetics of ependymoma

    PubMed Central

    Yao, Yuan; Mack, Stephen C.; Taylor, Michael D.

    2011-01-01

    Brain tumors are the leading cause of cancer death in children, with ependymoma being the third most common and posing a significant clinical burden. Its mechanism of pathogenesis, reliable prognostic indicators, and effective treatments other than surgical resection have all remained elusive. Until recently, ependymoma research was hindered by the small number of tumors available for study, low resolution of cytogenetic techniques, and lack of cell lines and animal models. Ependymoma heterogeneity, which manifests as variations in tumor location, patient age, histological grade, and clinical behavior, together with the observation of a balanced genomic profile in up to 50% of cases, presents additional challenges in understanding the development and progression of this disease. Despite these difficulties, we have made significant headway in the past decade in identifying the genetic alterations and pathways involved in ependymoma tumorigenesis through collaborative efforts and the application of microarray-based genetic (copy number) and transcriptome profiling platforms. Genetic characterization of ependymoma unraveled distinct mRNA-defined subclasses and led to the identification of radial glial cells as its cell type of origin. This review summarizes our current knowledge in the molecular genetics of ependymoma and proposes future research directions necessary to further advance this field. PMID:21959044

  19. A paramagnetic molecular voltmeter.

    PubMed

    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 (R(1)) and transverse (R(2)) relaxation rates were separated by applying lineshape analysis to progressive saturation spectra. The ratio of measured R(1) 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

  20. 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

  1. [Advances in Molecular Cloning].

    PubMed

    Ashwini, M; Murugan, S B; Balamurugan, S; Sathishkumar, R

    2016-01-01

    "Molecular cloning" meaning creation of recombinant DNA molecules has impelled advancement throughout life sciences. DNA manipulation has become easy due to powerful tools showing exponential growth in applications and sophistication of recombinant DNA technology. Cloning genes has become simple what led to an explosion in the understanding of gene function by seamlessly stitching together multiple DNA fragments or by the use of swappable gene cassettes, maximizing swiftness and litheness. A novel archetype might materialize in the near future with synthetic biology techniques that will facilitate quicker assembly and iteration of DNA clones, accelerating the progress of gene therapy vectors, recombinant protein production processes and new vaccines by in vitro chemical synthesis of any in silico-specified DNA construct. The advent of innovative cloning techniques has opened the door to more refined applications such as identification and mapping of epigenetic modifications and high-throughput assembly of combinatorial libraries. In this review, we will examine the major breakthroughs in cloning techniques and their applications in various areas of biological research that have evolved mainly due to easy construction of novel expression systems. PMID:27028806

  2. 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.

  3. 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.

  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. 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…

  6. Trapping cold molecular hydrogen.

    PubMed

    Seiler, Ch; Hogan, S D; Merkt, F

    2011-11-14

    Translationally cold H(2) molecules excited to non-penetrating |M(J)| = 3 Rydberg states of principal quantum number in the range 21-37 have been decelerated and trapped using time-dependent inhomogeneous electric fields. The |M(J)| = 3 Rydberg states were prepared from the X (1)Σ(+)(u)(v = 0, J = 0) ground state using a resonant three-photon excitation sequence via the B (1)Σ(+)(u)(v = 3, J = 1) and I (1)Π(g) (v = 0, J = 2) intermediate states and circularly polarized laser radiation. The circular polarization of the vacuum ultraviolet radiation used for the B ← X transition was generated by resonance-enhanced four-wave mixing in xenon and the degree of circular polarization was determined to be 96%. To analyse the deceleration and trapping experiments, the Stark effect in Rydberg states of molecular hydrogen was calculated using a matrix diagonalization procedure similar to that presented by Yamakita et al., J. Chem. Phys., 2004, 121, 1419. Particular attention was given to the prediction of zero-field positions of low-l states and of avoided crossings between Rydberg-Stark states with different values of |M(J)|. The calculated Stark maps and probabilities for diabatic traversal of the avoided crossings were used as input to Monte-Carlo particle-trajectory simulations. These simulations provide a quantitatively satisfactory description of the experimental data and demonstrate that particle loss caused by adiabatic traversals of avoided crossings between adjacent |M(J)| = 3 Stark states of H(2) is small at principal quantum numbers beyond n = 25. The main source of trap losses was found to be from collisional processes. Predissociation following the absorption of blackbody radiation is estimated to be the second most important trap-loss mechanism at room temperature, and trap loss by spontaneous emission is negligible under our experimental conditions. PMID:21818497

  7. Molecular imaging in atherosclerosis

    PubMed Central

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

    2010-01-01

    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

  8. 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.

  9. [Molecular Subtypes of Gastric Cancer].

    PubMed

    Hatogai, Ken; Doi, Toshihiko

    2016-03-01

    Gastric cancer has been classified based on the pathological characteristics including microscopic configuration and growth pattern. Although these classifications have been used in studies investigating prognosis and recurrence pattern, they are not considered for decisions regarding the therapeutic strategy. In the ToGA study, trastuzumab, an anti-HER2 monoclonal antibody, demonstrated clinical efficacy for gastric cancer with HER2 overexpression or HER2 gene amplification. Based on these findings of the ToGA study, the definition of HER2-positive gastric cancer was established. Thereafter, several molecular targeted agents, including agents targeting other receptor tyrosine kinases, have been investigated in gastric cancer. However, to date no biomarker, except HER2, has been established. Based on the recent technological development in the field of gene analysis, a comprehensive molecular evaluation of gastric cancer was performed as part of The Cancer Genome Atlas (TCGA) project, and a new molecular classification was proposed that divided gastric cancer into the following 4 subtypes: tumors positive for Epstein-Barr virus, microsatellite instability tumors, genomically stable tumors, and tumors with chromosomal instability. Each subtype has specific molecular alterations including gene mutation and amplification, DNA methylation, and protein overexpression. Additionally, some subtypes were suggested to be correlated with the clinicopathological characteristics or as targets of some molecular targeted agents that are currently under development. The new molecular classification is expected to be a roadmap for patient stratification and clinical trials on molecular targeted therapies in gastric cancer. PMID:27067842

  10. 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.

  11. 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

  12. Molecular wire and interface for bioelectronic molecular devices

    NASA Astrophysics Data System (ADS)

    Aizawa, M.; Khan, G. F.; Shinohara, H.; Ikariyama, Y.

    1992-07-01

    Protein molecules have successfully been incorporated in bioelectronic molecular devices through the molecular wire or interface of conducting polymer. Such enzymes as glucose oxidase and fructose dehydrogenase were adsorbed on the platinum electrode surface, which was followed by the electropolymerization of pyrrole to deposit an ultimately thin layer of polypyrrole on the electrode surface. Alcohol dehydrogenase was immobilized in a polypyrrole membrane with NAD and Meldora's blue in the similar manner on the electrode surface. The electron transfer from the electron transfer sites of these enzymes to the corresponding electrode has been promoted through the molecular wire. It has been demonstrated that the enzyme activity is modulated by changing the potential of the electrode with which the enzyme is connected through the molecular wire. On the basis of the electronic characteristics of these enzyme proteins the design principles of biomolecular electron devices have been proposed.

  13. Educational and Demographic Profile: Del Norte County.

    ERIC Educational Resources Information Center

    California Postsecondary Education Commission, 2004

    2004-01-01

    This profile uniquely presents a variety of educational and socioeconomic information for Del Norte County, nearby counties, and the state. The profile highlights the relationship between various factors that affect the economic well-being of individuals and communities. This presentation of information provides a framework for enhanced…

  14. Del Mod System. 1972 Annual Report.

    ERIC Educational Resources Information Center

    Purnell, Charlotte H.

    The overall aim of the Del Mod System is the improvement of science programs taught in Delaware schools; it is a working agreement among the University of Delaware, Delaware Technical and Community College, Delaware State College, State Department of Public Instruction, industry, and the schools. It was formed to bring about changes in science…

  15. Andrea del Sarto rehabilitated: a psychoanalytic emendation.

    PubMed

    Trosman, Harry

    2002-01-01

    Ernest Jones's "The Influence of Andrea del Sarto's Wife on His Art" (1913) is an early example of psychoanalysis applied to the study of a prominent painter. Greatly influenced by Freud's Leonardo da Vinci and a Memory of His Childhood, Jones gave excessive credence to Vasari's highly prejudicial account of the life of del Sarto, on which the study relied heavily. Jones attempted to account psychologically for the circumstance that del Sarto, though highly skilled and "faultless," was not the equal of the three preeminent masters of the Italian High Renaissance: Leonardo, Michelangelo, and Raphael. Jones's uncritical acceptance of the Vasari biography encouraged him to view Sarto's assumed deficiency as the result of excessive attachment to his wife, a pathological uxoriousness. A contemporary psychoanalytic perspective, with its emphasis on the emotive response of the analyst, requires us to pay attention to the evocative nature of the work of the artist, an approach Jones neglected. In an examination of several paintings, the artist's sensitivity to the position of the spectator is explored, as is the interest in involving the viewer spatially and emotionally. An appreciation for the viewer's position is consistent with a capacity for using projected internal objects for creative purposes. The presence of this capacity suggests a revised view of del Sarto's contribution to art and of his relationship with his wife. PMID:12580329

  16. 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.

  17. 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.

  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. Molecularly Regulated Reversible DNA Polymerization.

    PubMed

    Chen, Niancao; Shi, Xuechen; Wang, Yong

    2016-06-01

    Natural polymers are synthesized and decomposed under physiological conditions. However, it is challenging to develop synthetic polymers whose formation and reversibility can be both controlled under physiological conditions. Here we show that both linear and branched DNA polymers can be synthesized via molecular hybridization in aqueous solutions, on the particle surface, and in the extracellular matrix (ECM) without the involvement of any harsh conditions. More importantly, these polymers can be effectively reversed to dissociate under the control of molecular triggers. Since nucleic acids can be conjugated with various molecules or materials, we anticipate that molecularly regulated reversible DNA polymerization holds potential for broad biological and biomedical applications. PMID:27100911

  20. Time delay in molecular photoionization

    NASA Astrophysics Data System (ADS)

    Hockett, P.; Frumker, E.; Villeneuve, D. M.; Corkum, P. B.

    2016-05-01

    Time-delays in the photoionization of molecules are investigated. As compared to atomic ionization, the time-delays expected from molecular ionization present a much richer phenomenon, with a strong spatial dependence due to the anisotropic nature of the molecular scattering potential. We investigate this from a scattering theory perspective, and make use of molecular photoionization calculations to examine this effect in representative homonuclear and hetronuclear diatomic molecules, nitrogen and carbon monoxide. We present energy and angle-resolved maps of the Wigner delay time for single-photon valence ionization, and discuss the possibilities for experimental measurements.

  1. 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.

  2. 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.

  3. Nucleic acids and molecular biology

    SciTech Connect

    Eckstein, F.; Lilley, D.M.J.

    1988-01-01

    Molecular biology has always been a discipline of rapid development. Despite this the authors are presently experiencing a period of unprecedented proliferation of information in nucleic acid studies and molecular biology. These areas are intimately interwoven, so that each influences the other to their mutual benefit. The rapid growth in information leads to ever-increasing specialization. The authors present the series Nucleic Acids and Molecular Biology. It comprises focused review articles by active researchers who report on the newest developments in their areas of particular interest.

  4. Thermopower measurements in molecular junctions.

    PubMed

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

    2016-08-01

    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. PMID:27277330

  5. Molecular Hydrodynamics from Memory Kernels.

    PubMed

    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. PMID:27104730

  6. Molecular and phenotypic characterization of infectious bursal disease virus isolates.

    PubMed

    Dormitorio, T V; Giambrone, J J; Guo, K; Jackwood, D J

    2007-06-01

    Two infectious bursal disease viruses (IBDVs 1174 and V1) were isolated from IBDV-vaccinated broiler flocks in California and Georgia. These flocks had a history of subclinical immunosuppression. These isolates are commonly used in IBDV progeny challenge studies at Auburn, AL, as well as vaccine manufacturer's vaccine efficacy studies, because they come from populated poultry-producing states, and are requested by poultry veterinarians from those states. Nested polymerase chain reaction (PCR) generated viral genome products for sequencing. A 491-bp segment from the VP2 gene, covering the hypervariable region, from each isolate was analyzed and compared with previously sequenced isolates. Sequence analysis showed that they were more closely related to the Delaware (Del) E antigenic variant than they are to the Animal Health Plant Inspection Service (APHIS) standard, both at the nucleotide level (96%, 97%) and at the amino acid level (94%, 97%). Both isolates had the glutamine to lysine shift in amino acid 249 which has been reported to be critical in binding the virus neutralizing Mab B69. Phenotypic studies showed that both isolates produced rapid atrophy of the bursae and weight loss, without the edematous bursal phase, in 2-wk-old commercial broilers having antibody against IBDV. A progeny challenge study showed both isolates produced more atrophy of the bursae (less percentage of protection) than the Del E isolate. Molecular and phenotypic data of these important IBDV isolates help in the improved detection and control of this continually changing and important viral pathogen of chickens. PMID:17626491

  7. 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

  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. 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

  10. Investigating Evolutionary Questions Using Online Molecular Databases.

    ERIC Educational Resources Information Center

    Puterbaugh, Mary N.; Burleigh, J. Gordon

    2001-01-01

    Recommends using online molecular databases as teaching tools to illustrate evolutionary questions and concepts while introducing students to public molecular databases. Provides activities in which students make molecular comparisons between species. (YDS)

  11. Fabrication of molecular tension probes.

    PubMed

    Kim, Sung Bae; Fujii, Rika

    2016-01-01

    A unique bioluminescent imaging probe is introduced for illuminating molecular tension appended by protein-protein interactions (PPIs) of interest. A full-length luciferase is sandwiched between two proteins of interest via minimal flexible linkers. The ligand-activated PPIs append intramolecular tension to the sandwiched luciferase, boosting or dropping the enzymatic activity in a quantitative manner. This method guides construction of a new lineage of bioassays for determining molecular tension appended by ligand-activated PPIs. The summary of the method is: •Molecular tension appended by protein-protein interactions (PPI) is visualized with a luciferase.•Estrogen activities are quantitatively illuminated with the molecular tension probes.•Full-length Renilla luciferase enhances the optical intensities after bending by PPI. PMID:27222821

  12. 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.

  13. 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.

  14. 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...

  15. Imaging molecular orbitals using photoionization

    NASA Astrophysics Data System (ADS)

    Santra, Robin

    2006-10-01

    The interpretation of a recent experiment using high-order harmonic generation [Itatani et al., Nature 432 (2004) 867] as a measurement of the highest occupied molecular orbital of a molecule is conceptually problematic, even if the independent-particle picture is taken seriously. Guided by the relationship between the amplitude for one-photon-induced electron emission and the electron-ion recombination amplitude in the three-step model of high-order harmonic generation, it is argued that synchrotron-based photoionization might be a superior approach to imaging molecular orbitals. Within the Hartree-Fock independent-particle picture, the molecular-frame photoelectron angular distributions, measured as a function of photon energy, could be used to reconstruct all orbitals occupied in the Hartree-Fock ground state of the molecule investigated. It is suggested that laser alignment techniques could be employed to facilitate the measurement of the molecular-frame photoelectron angular distributions.

  16. Molecular Mechanism of Water Evaporation

    NASA Astrophysics Data System (ADS)

    Nagata, Yuki; Usui, Kota; Bonn, Mischa

    2015-12-01

    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.

  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 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....

  19. 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)

  20. 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)

  1. Emerging molecular phenotypes of asthma.

    PubMed

    Ray, Anuradha; Oriss, Timothy B; Wenzel, Sally E

    2015-01-15

    Although asthma has long been considered a heterogeneous disease, attempts to define subgroups of asthma have been limited. In recent years, both clinical and statistical approaches have been utilized to better merge clinical characteristics, biology, and genetics. These combined characteristics have been used to define phenotypes of asthma, the observable characteristics of a patient determined by the interaction of genes and environment. Identification of consistent clinical phenotypes has now been reported across studies. Now the addition of various 'omics and identification of specific molecular pathways have moved the concept of clinical phenotypes toward the concept of molecular phenotypes. The importance of these molecular phenotypes is being confirmed through the integration of molecularly targeted biological therapies. Thus the global term asthma is poised to become obsolete, being replaced by terms that more specifically identify the pathology associated with the disease. PMID:25326577

  2. Molecular Aggregation in Disodium Cromoglycate

    NASA Astrophysics Data System (ADS)

    Singh, Gautam; Agra-Kooijman, D.; Collings, P. J.; Kumar, Satyendra

    2012-02-01

    Details of molecular aggregation in the mesophases of the anti-asthmatic drug disodium cromoglycate (DSCG) have been studied using x-ray synchrotron scattering. The results show two reflections, one at wide angles corresponding to π-π stacking (3.32 å) of molecules, and the other at small angles which is perpendicular to the direction of molecular stacking and corresponds to the distance between the molecular aggregates. The latter varies from 35 - 41 å in the nematic (N) phase and 27 -- 32 å in the columnar (M) phase. The temperature evolution of the stack height, positional order correlations in the lateral direction, and orientation order parameter were determined in the N, M, and biphasic regions. The structure of the N and M phases and the nature of the molecular aggregation, together with their dependence on temperature and concentration, will be presented.

  3. 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. PMID:18393670

  4. 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).

  5. Fabrication of molecular tension probes

    PubMed Central

    Kim, Sung Bae; Fujii, Rika

    2016-01-01

    A unique bioluminescent imaging probe is introduced for illuminating molecular tension appended by protein–protein interactions (PPIs) of interest. A full-length luciferase is sandwiched between two proteins of interest via minimal flexible linkers. The ligand-activated PPIs append intramolecular tension to the sandwiched luciferase, boosting or dropping the enzymatic activity in a quantitative manner. This method guides construction of a new lineage of bioassays for determining molecular tension appended by ligand-activated PPIs. The summary of the method is: • Molecular tension appended by protein–protein interactions (PPI) is visualized with a luciferase. • Estrogen activities are quantitatively illuminated with the molecular tension probes. • Full-length Renilla luciferase enhances the optical intensities after bending by PPI. PMID:27222821

  6. 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. PMID:16504405

  7. Molecular Imaging in Genetic Medicine

    PubMed Central

    Jacob, Ayden; Van Gestel, Frederick; Yaghoubi, Shahriar

    2016-01-01

    The field of biomedical imaging has made significant advances in recent times. This includes extremely high-resolution anatomic imaging and functional imaging of physiologic and pathologic processes as well as novel modalities in optical imaging to evaluate molecular features within the cellular environment. The latter has made it possible to image phenotypic markers of various genotypes that are implicated in human development, behavior, and disease. This article discusses the role of molecular imaging in genetic and precision medicine.  PMID:27186447

  8. [Knowledgebases in postgenomic molecular biology].

    PubMed

    Lisitsa, A V; Shilov, B V; Evdokimov, P A; Gusev, S A

    2010-01-01

    Knowledgebases can become an effective tool essentially raising quality of information retrieval in molecular biology, promoting the development of new methods of education and forecasting of the biomedical R&D. Knowledge-based technologies should induce "paradigm shift" in the life science due to integrative focusing of research groups towards the challenges of postgenomic era. This paper debates concept of the knowledgebase, which exploits web usage mining to personalize the access of molecular biologist to the Internet resources. PMID:21328913

  9. 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

  10. Hydrogen storage in molecular compounds.

    PubMed

    Mao, Wendy L; Mao, Ho-Kwang

    2004-01-20

    At low temperature (T) and high pressure (P), gas molecules can be held in ice cages to form crystalline molecular compounds that may have application for energy storage. We synthesized a hydrogen clathrate hydrate, H(2)(H(2)O)(2), that holds 50 g/liter hydrogen by volume or 5.3 wt %. The clathrate, synthesized at 200-300 MPa and 240-249 K, can be preserved to ambient P at 77 K. The stored hydrogen is released when the clathrate is warmed to 140 K at ambient P. Low T also stabilizes other molecular compounds containing large amounts of molecular hydrogen, although not to ambient P, e.g., the stability field for H(2)(H(2)O) filled ice (11.2 wt % molecular hydrogen) is extended from 2,300 MPa at 300 K to 600 MPa at 190 K, and that for (H(2))(4)CH(4) (33.4 wt % molecular hydrogen) is extended from 5,000 MPa at 300 K to 200 MPa at 77 K. These unique characteristics show the potential of developing low-T molecular crystalline compounds as a new means for hydrogen storage. PMID:14711993

  11. Electron transport through molecular junctions

    NASA Astrophysics Data System (ADS)

    Zimbovskaya, Natalya A.; Pederson, Mark R.

    2011-12-01

    At present, metal-molecular tunnel junctions are recognized as important active elements in molecular electronics. This gives a strong motivation to explore physical mechanisms controlling electron transport through molecules. In the last two decades, an unceasing progress in both experimental and theoretical studies of molecular conductance has been demonstrated. In the present work we give an overview of theoretical methods used to analyze the transport properties of metal-molecular junctions as well as some relevant experiments and applications. After a brief general description of the electron transport through molecules we introduce a Hamiltonian which can be used to analyze electron-electron, electron-phonon and spin-orbit interactions. Then we turn to description of the commonly used transport theory formalisms including the nonequilibrium Green’s functions based approach and the approach based on the “master” equations. We discuss the most important effects which could be manifested through molecules in electron transport phenomena such as Coulomb, spin and Frank-Condon blockades, Kondo peak in the molecular conductance, negative differential resistance and some others. Bearing in mind that first principles electronic structure calculations are recognized as the indispensable basis of the theory of electron transport through molecules, we briefly discuss the main equations and some relevant applications of the density functional theory which presently is often used to analyze important characteristics of molecules and molecular clusters. Finally, we discuss some kinds of nanoelectronic devices built using molecules and similar systems such as carbon nanotubes, various nanowires and quantum dots.

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

    PubMed

    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

  13. Correction of human phospholamban R14del mutation associated with cardiomyopathy using targeted nucleases and combination therapy.

    PubMed

    Karakikes, Ioannis; Stillitano, Francesca; Nonnenmacher, Mathieu; Tzimas, Christos; Sanoudou, Despina; Termglinchan, Vittavat; Kong, Chi-Wing; Rushing, Stephanie; Hansen, Jens; Ceholski, Delaine; Kolokathis, Fotis; Kremastinos, Dimitrios; Katoulis, Alexandros; Ren, Lihuan; Cohen, Ninette; Gho, Johannes M I H; Tsiapras, Dimitrios; Vink, Aryan; Wu, Joseph C; Asselbergs, Folkert W; Li, Ronald A; Hulot, Jean-Sebastien; Kranias, Evangelia G; Hajjar, Roger J

    2015-01-01

    A number of genetic mutations is associated with cardiomyopathies. A mutation in the coding region of the phospholamban (PLN) gene (R14del) is identified in families with hereditary heart failure. Heterozygous patients exhibit left ventricular dilation and ventricular arrhythmias. Here we generate induced pluripotent stem cells (iPSCs) from a patient harbouring the PLN R14del mutation and differentiate them into cardiomyocytes (iPSC-CMs). We find that the PLN R14del mutation induces Ca(2+) handling abnormalities, electrical instability, abnormal cytoplasmic distribution of PLN protein and increases expression of molecular markers of cardiac hypertrophy in iPSC-CMs. Gene correction using transcription activator-like effector nucleases (TALENs) ameliorates the R14del-associated disease phenotypes in iPSC-CMs. In addition, we show that knocking down the endogenous PLN and simultaneously expressing a codon-optimized PLN gene reverses the disease phenotype in vitro. Our findings offer novel strategies for targeting the pathogenic mutations associated with cardiomyopathies. PMID:25923014

  14. 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

  15. 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

  16. 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

  17. 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.

  18. Design and Development of Molecular Imaging Probes

    PubMed Central

    Chen, Kai; Chen, Xiaoyuan

    2013-01-01

    Molecular imaging, the visualization, characterization and measurement of biological processes at the cellular, subcellular level, or even molecular level in living subjects, has rapidly gained importance in the dawning era of personalized medicine. Molecular imaging takes advantage of the traditional diagnostic imaging techniques and introduces molecular imaging probes to determine the expression of indicative molecular markers at different stages of diseases and disorders. As a key component of molecular imaging, molecular imaging probe must be able to specifically reach the target of interest in vivo while retaining long enough to be detected. A desirable molecular imaging probe with clinical translation potential is expected to have unique characteristics. Therefore, design and development of molecular imaging probe is frequently a challenging endeavor for medicinal chemists. This review summarizes the general principles of molecular imaging probe design and some fundamental strategies of molecular imaging probe development with a number of illustrative examples. PMID:20388106

  19. Grados de comprobación de estudios de terapias integrales (PDQ®)—Versión para profesionales de salud

    Cancer.gov

    Información acerca de cómo sopesar la fuerza de los datos probatorios obtenidos de los estudios de investigación sobre terapias integrales, alternativas y complementarias en seres humanos con cáncer.

  20. 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.

  1. 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).

  2. 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.

  3. 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

  4. Molecular abundances in the Sagittarius A molecular cloud

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Irvine, W. M.; Friberg, P.

    1992-01-01

    We have obtained column densities for HCO(+), HCO, HCS(+), C3H2, HC5N, SiO, OCS, HCOOH, CH3CH2OH, and CH3CCH toward Sgr A. The fractional abundance of SiO relative to molecular hydrogen in Sgr A is comparable to that for the Orion plateau, about 10 exp-7 to 10 exp -8, which may be a typical value for hot clouds. The abundances of HCO, CH3CH2OH, and CH3CCH all appear to be enhanced relative to other molecular clouds such as Sgr B2.

  5. Sanger Sequencing for BRCA1 c.68_69del, BRCA1 c.5266dup and BRCA2 c.5946del Mutation Screen on Pap Smear Cytology Samples

    PubMed Central

    Lee, Sin Hang; Zhou, Shaoxia; Zhou, Tianjun; Hong, Guofan

    2016-01-01

    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. PMID:26867194

  6. 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

    2016-01-01

    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. PMID:26867194

  7. Molecular classification of gastric cancer.

    PubMed

    Chia, N-Y; Tan, P

    2016-05-01

    Gastric cancer (GC), a heterogeneous disease characterized by epidemiologic and histopathologic differences across countries, is a leading cause of cancer-related death. Treatment of GC patients is currently suboptimal due to patients being commonly treated in a uniform fashion irrespective of disease subtype. With the advent of next-generation sequencing and other genomic technologies, GCs are now being investigated in great detail at the molecular level. High-throughput technologies now allow a comprehensive study of genomic and epigenomic alterations associated with GC. Gene mutations, chromosomal aberrations, differential gene expression and epigenetic alterations are some of the genetic/epigenetic influences on GC pathogenesis. In addition, integrative analyses of molecular profiling data have led to the identification of key dysregulated pathways and importantly, the establishment of GC molecular classifiers. Recently, The Cancer Genome Atlas (TCGA) network proposed a four subtype classification scheme for GC based on the underlying tumor molecular biology of each subtype. This landmark study, together with other studies, has expanded our understanding on the characteristics of GC at the molecular level. Such knowledge may improve the medical management of GC in the future. PMID:26861606

  8. Visualization of the Gödel universe

    NASA Astrophysics Data System (ADS)

    Buser, M.; Kajari, E.; Schleich, W. P.

    2013-01-01

    The standard model of modern cosmology, which is based on the Friedmann-Lemaître-Robertson-Walker metric, allows the definition of an absolute time. However, there exist (cosmological) models consistent with the theory of general relativity for which such a definition cannot be given since they offer the possibility for time travel. The simplest of these models is the cosmological solution discovered by Kurt Gödel, which describes a homogeneous, rotating universe. Disregarding the paradoxes that come along with the abolishment of causality in such space-times, we are interested in the purely academic question of how an observer would visually perceive the time travel of an object in Gödel's universe. For this purpose, we employ the technique of ray tracing, a standard tool in computer graphics, and visualize various scenarios to bring out the optical effects experienced by an observer located in this universe. In this way, we provide a new perspective on the space-time structure of Gödel's model.

  9. Genomic instability establishes dependencies on acquired gene regulatory networks: A novel role of p62 in myeloid malignancies with del(5q)

    PubMed Central

    Fang, Jing; Starczynowski, Daniel T

    2015-01-01

    MiR-146a deletion is a driving molecular event in del(5q) myeloid malignancies, which acquire dependency on a nuclear factor kappa B (NF-κB) regulatory network. p62, a neighboring haploid 5q gene, is induced by NF-κB and required to sustain TRAF6-mediated NF-κB activation. Interfering with p62/TRAF6 binding may have a therapeutic benefit in miR-146a–deficient leukemic cells. PMID:27308507

  10. 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.

  11. Molecular Architectonic on Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Barth, Johannes V.

    2007-05-01

    The engineering of highly organized systems from instructed molecular building blocks opens up new vistas for the control of matter and the exploration of nanodevice concepts. Recent investigations demonstrate that well-defined surfaces provide versatile platforms for steering and monitoring the assembly of molecular nanoarchitectures in exquisite detail. This review delineates the principles of noncovalent synthesis on metal substrates under ultrahigh vacuum conditions and briefly assesses the pertaining terminology—self-assembly, self-organization, and self-organized growth. It presents exemplary scanning-tunneling-microscopy observations, providing atomistic insight into the self-assembly of organic clusters, chains, and superlattices, and the metal-directed assembly of low-dimensional coordination architectures. This review also describes hierarchic-assembly protocols leading to intricate multilevel order. Molecular architectonic on metal surfaces represents a versatile rationale to realize structurally complex nanosystems with specific shape, composition, and functional properties, which bear promise for technological applications.

  12. Bioconjugate-Based Molecular Umbrellas

    PubMed Central

    Janout, Vaclav; Regen, Steven L.

    2009-01-01

    Molecular umbrellas are “amphomorphic” compounds that can produce a hydrophobic or a hydrophilic exterior when exposed to a hydrophobic or hydrophilic microenvironment, respectively. Such molecules are composed of two or more facial amphiphiles that are connected to a central scaffold. Molecular umbrellas that have been synthesized to date, using bile acids as umbrella “walls”, polyamines such as spermidine and spermine as scaffold material, and L-lysine as “branches”, have been found capable of transporting certain hydrophilic peptides, nucleotides, and oligonucleotides across liposomal membranes by passive diffusion. They have also have been shown to increase in the water solubility and hydrolytic stability of a hydrophobic drug, and to exhibit significant antiviral activity. The ability of a fluorescently-labeled molecular umbrella to readily enter live HeLa cells suggests that such conjugates could find use as drug carriers. PMID:19053303

  13. Molecular Processes in Biological Thermosensation

    PubMed Central

    Digel, I.; Kayser, P.; Artmann, G. M.

    2008-01-01

    Since thermal gradients are almost everywhere, thermosensation could represent one of the oldest sensory transduction processes that evolved in organisms. There are many examples of temperature changes affecting the physiology of living cells. Almost all classes of biological macromolecules in a cell (nucleic acids, lipids, proteins) can present a target of the temperature-related stimuli. This review discusses some features of different classes of temperature-sensing molecules as well as molecular and biological processes that involve thermosensation. Biochemical, structural, and thermodynamic approaches are applied in the paper to organize the existing knowledge on molecular mechanisms of thermosensation. Special attention is paid to the fact that thermosensitive function cannot be assigned to any particular functional group or spatial structure but is rather of universal nature. For instance, the complex of thermodynamic, structural, and functional features of hemoglobin family proteins suggests their possible accessory role as “molecular thermometers”. PMID:20130806

  14. Molecular diagnostics of neurodegenerative disorders

    PubMed Central

    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. PMID:26442283

  15. 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.

  16. Molecular spectroscopic analyses of gelatin

    NASA Astrophysics Data System (ADS)

    Ibrahim, Medhat; Mahmoud, Abdel Aziz; Osman, Osama; Abd El-Aal, Mohamed; Eid, May

    2011-10-01

    The molecular structure of gelatin was studied using Fourier transform infrared spectroscopy FTIR. The spectrum is subjected to deconvolution in order to elucidate the constituents of the molecular structure. B3LYP/6-31g** was used to study 13 amino acids then the scaled spectrum was compared to those of protein in order to describe the contribution of each amino acid into protein structure. A special interest was paid to the NH and C dbnd O region. The reactivity of each amino acid was studied in terms of some important physical parameters like total dipole moment and HOMO/LUMO which describe the interaction of amino acid with their surrounding molecules. Results indicated that B3LYP/6-31g** model is a suitable and precise method for studying molecular structure of protein.

  17. 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.

  18. 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.

  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. 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.

  1. Molecular SPECT Imaging: An Overview

    PubMed Central

    Khalil, Magdy M.; Tremoleda, Jordi L.; Bayomy, Tamer B.; Gsell, Willy

    2011-01-01

    Molecular imaging has witnessed a tremendous change over the last decade. Growing interest and emphasis are placed on this specialized technology represented by developing new scanners, pharmaceutical drugs, diagnostic agents, new therapeutic regimens, and ultimately, significant improvement of patient health care. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) have their signature on paving the way to molecular diagnostics and personalized medicine. The former will be the topic of the current paper where the authors address the current position of the molecular SPECT imaging among other imaging techniques, describing strengths and weaknesses, differences between SPECT and PET, and focusing on different SPECT designs and detection systems. Radiopharmaceutical compounds of clinical as well-preclinical interest have also been reviewed. Moreover, the last section covers several application, of μSPECT imaging in many areas of disease detection and diagnosis. PMID:21603240

  2. A Description of Del Mod and Its Final Evaluation, Final Report, Volume I.

    ERIC Educational Resources Information Center

    Purnell, Charlotte H.; Bolig, John R.

    This monograph presents an overview of five Del Mod System final reports, comments by the project director, financial structure of the Del Mod System, and descriptions of Del Mod Projects. The Del Mod System was concerned with changing the science and mathematics education programs in the state of Delaware. Between 1970 and 1976, Del Mod conducted…

  3. Molecular thermometry of energetic materials

    SciTech Connect

    Fishbine, B.H.; Lippert, T.; Dick, J.J.

    1997-07-01

    When a solid object with a velocity <1 km/s strikes a solid high explosive, the increase in the bulk temperature of the explosive is usually too low to thermally initiate it. It is believed, however, that the energy in the stress or shock wave created by the impact can heat individual microscopic regions that ignite and cause detonation. Although many mechanisms have been suggested for how the impact energy creates these hot spots, there has been no real-time observation of their growth at early times because of their small dimensions (estimated to be 0.1--10 {micro}m), the short times required for their growth (estimated to be 0.5 {micro}s--1 ms), and because their temperatures are too low (estimated to be <2,000 K) for them to radiate much energy in the visible. One possible way to observe early hot-spot growth is to measure temperature-dependent changes in the optical properties--absorbance, diffuse reflection, Raman spectra--of either the components of the explosive or of molecules attached to them. This temperature measurement technique is called molecular thermometry. Molecular thermometers can respond to heating within a few picoseconds with spatial resolution that can, in principle, approach the diameter of a single molecule. Temperatures as high as 900 C have been measured by molecular thermometers in laser-pulse-heated polymers. The authors discuss the literature pertaining to molecular thermometry, the effect of stress on the optical properties of some molecules that may be used as thermometers, and experiments that have used molecular thermometry to probe, on the picosecond time scale, shock excitation of the vibrational modes of molecules of energetic material. The authors also suggest ways to use molecular thermometers to observe hot-spot formation in PBX9501, a plastic-bonded explosive, subjected to impact.

  4. Molecular replacement: tricks and treats

    SciTech Connect

    Abergel, Chantal

    2013-11-01

    To be successful, molecular replacement relies on the quality of the model and of the crystallographic data. Some tricks that could be applied to the models or to the crystal to increase the success rate of MR are discussed here. Molecular replacement is the method of choice for X-ray crystallographic structure determination provided that suitable structural homologues are available in the PDB. Presently, there are ∼80 000 structures in the PDB (8074 were deposited in the year 2012 alone), of which ∼70% have been solved by molecular replacement. For successful molecular replacement the model must cover at least 50% of the total structure and the C{sub α} r.m.s.d. between the core model and the structure to be solved must be less than 2 Å. Here, an approach originally implemented in the CaspR server (http://www.igs.cnrs-mrs.fr/Caspr2/index.cgi) based on homology modelling to search for a molecular-replacement solution is discussed. How the use of as much information as possible from different sources can improve the model(s) is briefly described. The combination of structural information with distantly related sequences is crucial to optimize the multiple alignment that will define the boundaries of the core domains. PDB clusters (sequences with ≥30% identical residues) can also provide information on the eventual changes in conformation and will help to explore the relative orientations assumed by protein subdomains. Normal-mode analysis can also help in generating series of conformational models in the search for a molecular-replacement solution. Of course, finding a correct solution is only the first step and the accuracy of the identified solution is as important as the data quality to proceed through refinement. Here, some possible reasons for failure are discussed and solutions are proposed using a set of successful examples.

  5. Topology of molecular interaction networks.

    PubMed

    Winterbach, Wynand; Van Mieghem, Piet; Reinders, Marcel; Wang, Huijuan; de Ridder, Dick

    2013-01-01

    Molecular interactions are often represented as network models which have become the common language of many areas of biology. Graphs serve as convenient mathematical representations of network models and have themselves become objects of study. Their topology has been intensively researched over the last decade after evidence was found that they share underlying design principles with many other types of networks.Initial studies suggested that molecular interaction network topology is related to biological function and evolution. However, further whole-network analyses did not lead to a unified view on what this relation may look like, with conclusions highly dependent on the type of molecular interactions considered and the metrics used to study them. It is unclear whether global network topology drives function, as suggested by some researchers, or whether it is simply a byproduct of evolution or even an artefact of representing complex molecular interaction networks as graphs.Nevertheless, network biology has progressed significantly over the last years. We review the literature, focusing on two major developments. First, realizing that molecular interaction networks can be naturally decomposed into subsystems (such as modules and pathways), topology is increasingly studied locally rather than globally. Second, there is a move from a descriptive approach to a predictive one: rather than correlating biological network topology to generic properties such as robustness, it is used to predict specific functions or phenotypes.Taken together, this change in focus from globally descriptive to locally predictive points to new avenues of research. In particular, multi-scale approaches are developments promising to drive the study of molecular interaction networks further. PMID:24041013

  6. Topology of molecular interaction networks

    PubMed Central

    2013-01-01

    Molecular interactions are often represented as network models which have become the common language of many areas of biology. Graphs serve as convenient mathematical representations of network models and have themselves become objects of study. Their topology has been intensively researched over the last decade after evidence was found that they share underlying design principles with many other types of networks. Initial studies suggested that molecular interaction network topology is related to biological function and evolution. However, further whole-network analyses did not lead to a unified view on what this relation may look like, with conclusions highly dependent on the type of molecular interactions considered and the metrics used to study them. It is unclear whether global network topology drives function, as suggested by some researchers, or whether it is simply a byproduct of evolution or even an artefact of representing complex molecular interaction networks as graphs. Nevertheless, network biology has progressed significantly over the last years. We review the literature, focusing on two major developments. First, realizing that molecular interaction networks can be naturally decomposed into subsystems (such as modules and pathways), topology is increasingly studied locally rather than globally. Second, there is a move from a descriptive approach to a predictive one: rather than correlating biological network topology to generic properties such as robustness, it is used to predict specific functions or phenotypes. Taken together, this change in focus from globally descriptive to locally predictive points to new avenues of research. In particular, multi-scale approaches are developments promising to drive the study of molecular interaction networks further. PMID:24041013

  7. Comprension de los conceptos de los enlaces ionico y covalente en estudiantes universitarios del primer curso de quimica general

    NASA Astrophysics Data System (ADS)

    Ballesteros Benavides, Maria Elvira

    Para este trabajo utilizamos el estudio de casos cualitativo que se llevo a cabo en una universidad privada de Puerto Rico. Empleamos como unidad de analisis el concepto de enlace quimico, ionico y covalente. Los participantes fueron los estudiantes de la seccion nocturna del curso de Quimica General I. La investigacion se desarrollo por medio de dos entrevistas de persona a persona, observaciones de las expresiones no verbales y la hoja de identificacion de conceptos. Para la triangulacion tomamos en consideracion las preconcepciones erroneas, las concepciones alternativas y el mapa de conceptos de cada participante. Preparamos un mapa de conceptos para el enlace quimico validado por un comite de expertos. Tambien, elaboramos los mapas de conceptos de los participantes que sirvieron para varios propositos: conocer la estructura conceptual, expresar los logros, hacer comparaciones e identificar la presencia de concepciones alternativas. Entre los hallazgos encontramos que todos los participantes poseen conocimiento previo de los enlaces quimicos ionico y covalente y dentro de ese conocimiento existen preconcepciones erroneas mas numerosas para el enlace ionico. Al principio del semestre el 50% de los participantes demostraron tener "carencia fuerte de conceptos" tanto para el enlace ionico como para el covalente. Al finalizar el semestre encontramos en el 40% de los participantes concepciones alternativas tanto para el enlace ionico como para el covalente y el 90% no lograron distinguir un enlace del otro. Nuestras conclusiones fueron que los participantes sin distincion del aprovechamiento academico demostraron tener la tendencia de "carencia fuerte de conceptos" tanto para el enlace ionico como para el covalente, presentaron dificultad al integrar los conceptos de los enlaces quimicos ionico y covalente que se pusieron de manifiesto al dar los ejemplos. Las preconcepciones erroneas contribuyen en el desarrollo de las concepciones alternativas. Ademas, los

  8. 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.

  9. Molecular Similarity in Computer-Aided Molecular Design.

    NASA Astrophysics Data System (ADS)

    Hodgkin, Edward E.

    Available from UMI in association with The British Library. Requires signed TDF. The quantitative measurement of how similar one molecule is to another is investigated as a potential aid to molecular design. The work concentrates on the comparison of electronic properties of molecules, in particular electron density distribution, molecular electrostatic potential, molecular electric field and frontier orbital wavefunctions. A novel formula for molecular similarity has been devised and applied to these four properties. An approximate representation of valence electron density is used, based on the notion that charge distribution in a large molecule may be built from transferable contributions from its constituent functional groups. Each of these contributions consists of a series of first-order gaussian functions. The electrostatic potentials and electric fields used in the similarity calculations are computed from atom -centered partial charges. The frontier orbital wavefunction comparisons are performed using the extended Huckel method. The four measures of similarity are related to chemical and biological data and shown to have possible applications in the area of drug design.

  10. 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…

  11. 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.

  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. Molecular biology of pancreatic cancer.

    PubMed

    Belda-Iniesta, Cristóbal; Ibáñez de Cáceres, Immaculada; Barriuso, Jorge; de Castro Carpeño, Javier; González Barón, Manuel; Feliú, Jaime

    2008-09-01

    Pancreatic cancer is a leading cause of cancer death. This devastating disease has the horrible honour of close to equal incidence and mortality rates. Late diagnosis and a constitutive resistance to every chemotherapy approach are responsible for this scenario. However, molecular biology tools in cooperation with translational efforts have dissected several secrets that underlie pancreatic cancer. Progressive acquisition of malignant, invasive phenotypes from pre-malignant lesions, recent revelations on core signalling pathways and new targeted designed trials offer a better future for pancreatic cancer patients. This review will summarise recent advances in the molecular biology of pancreatic cancer. PMID:18796369

  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 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. PMID:26661240

  16. 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

  17. Molecular dynamics and protein function

    PubMed Central

    Karplus, M.; Kuriyan, J.

    2005-01-01

    A fundamental appreciation for how biological macromolecules work requires knowledge of structure and dynamics. Molecular dynamics simulations provide powerful tools for the exploration of the conformational energy landscape accessible to these molecules, and the rapid increase in computational power coupled with improvements in methodology makes this an exciting time for the application of simulation to structural biology. In this Perspective we survey two areas, protein folding and enzymatic catalysis, in which simulations have contributed to a general understanding of mechanism. We also describe results for the F1 ATPase molecular motor and the Src family of signaling proteins as examples of applications of simulations to specific biological systems. PMID:15870208

  18. A sampling of molecular dynamics

    NASA Astrophysics Data System (ADS)

    Sindhikara, Daniel Jon

    The sheer vastness of the number of computations required to simulate a biological molecule puts incredible pressure on algorithms to be efficient while maintaining sufficient accuracy. This dissertation summarizes various projects whose purposes address the large span of types of problems in molecular dynamics simulations of biological systems including: increasing efficiency, measuring convergence, avoiding pitfalls, and an application and analysis of a biological system. Chapters 3 and 4 deal with an enhanced sampling algorithm called "replica exchange molecular dynamics" which is designed to speed-up molecular dynamics simulations. The optimization of a key parameter of these simulations is analyzed. In these successive projects, it was found conclusively that maximizing "exchange attempt frequency" is the most efficient way to run a replica exchange molecular dynamics simulation. Chapter 5 describes an enhanced metric for convergence in parallel simulations called the normalized ergodic measure. The metric is applied to several properties for several replica exchange simulations. Advantages of this metric over other methods are described. Chapter 6 describes the implementation and optimization of an enhanced sampling algorithm similar to replica exchange molecular dynamics called multicanonical algorithm replica exchange molecular dynamics. The algorithm was implemented into a biomolecular simulation suite called AMBER. Additionally several parameters were analyzed and optimized. In Chapter 7, a pitfall in molecular dynamics is observed in biological systems that is caused by negligent use of a simulation's "thermostat". It was found that if the same pseudorandom number seed were used for multiple systems, they eventually synchronize. In this project, synchronization was observed in biological molecules. Various negative effects including corruption of data are pointed out. Chapter 8 describes molecular dynamics simulation of NikR, a homotetrameric nickel

  19. [Opportunity and challenge on molecular epidemiology].

    PubMed

    Duan, G C; Chen, S Y

    2016-08-10

    Molecular epidemiology, a branch of epidemiology, combines the theories and methods, both in epidemiology and molecular biology. Molecular epidemiology mainly focuses on biological markers, describing the distribution, occurrence, development and prognosis of diseases at the molecular level. The completion of Human Genome Project and rapid development of Precision Medicine and Big Data not only offer the new development opportunities but also bring about a higher demand and new challenge for molecular epidemiology. PMID:27539332

  20. 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.

  1. Molecular outflows in starburst nuclei

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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 disk with mid-plane density n0 ˜ 200-1000 cm-3 and scale height 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 a SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  2. 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…

  3. 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)

  4. Molecular mobility on graphene nanoroads

    PubMed Central

    Jafary-Zadeh, Mehdi; Zhang, Yong-Wei

    2015-01-01

    We study molecular mobility on a graphene nanoroad (GNRD), a pristine graphene strip embedded in between two hydrogenated graphene domains serving as a nanoscale pathway for transporting admolecules. Our molecular dynamics simulations using a prototype physisorbed C60 admolecule demonstrate that the proposed GNRD is able to confine the diffusive motion of the admolecule within the nanoroad up to a certain temperature, depending on its width and edge type. Within the confinement regime, the width and edge-type of the GNRD also play an important role in the molecular motion. Specifically, when the GNRD width is narrower than the admolecule diameter, the admolecule performs one-dimensional hopping motion along the nanoroad. When the GNRD width is larger than the admolecule diameter, the admolecule moves only along one of its edges at low temperatures, and shuffle between two edges at high temperatures. We further show the admolecule motion on the zigzag-edged GRND is faster than that on the armchair-edged GRND with the same width and at the same temperature. These results can be well explained by analysing the potential energy surfaces of the systems. Since such hydrogenated graphene nanostructures have been experimentally realized, our results provide a valuable reference for constructing molecular conveyor circuits. PMID:26242303

  5. 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.

  6. Molecular Regionalization of the Diencephalon

    PubMed Central

    Martinez-Ferre, Almudena; Martinez, Salvador

    2012-01-01

    The anatomic complexity of the diencephalon depends on precise molecular and cellular regulative mechanisms orchestrated by regional morphogenetic organizers at the neural tube stage. In the diencephalon, like in other neural tube regions, dorsal and ventral signals codify positional information to specify ventro-dorsal regionalization. Retinoic acid, Fgf8, BMPs, and Wnts signals are the molecular factors acting upon the diencephalic epithelium to specify dorsal structures, while Shh is the main ventralizing signal. A central diencephalic organizer, the zona limitans intrathalamica (ZLI), appears after neurulation in the central diencephalic alar plate, establishing additional antero-posterior positional information inside diencephalic alar plate. Based on Shh expression, the ZLI acts as a morphogenetic center, which cooperates with other signals in thalamic specification and pattering in the alar plate of diencephalon. Indeed, Shh is expressed first in the basal plate extending dorsally through the ZLI epithelium as the development proceeds. Despite the importance of ZLI in diencephalic morphogenesis the mechanisms that regulate its development remain incompletely understood. Actually, controversial interpretations in different experimental models have been proposed. That is, experimental results have suggested that (i) the juxtaposition of the molecularly heterogeneous neuroepithelial areas, (ii) cell reorganization in the epithelium, and/or (iii) planar and vertical inductions in the neural epithelium, are required for ZLI specification and development. We will review some experimental data to approach the study of the molecular regulation of diencephalic regionalization, with special interest in the cellular mechanisms underlying planar inductions. PMID:22654731

  7. 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)

  8. 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

    2015-05-01

    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

  9. Thermoelectric efficiency of molecular junctions

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    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.

  10. 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.

  11. 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. PMID:27420149

  12. 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.

  13. Molecular diagnosis of intrahepatic cholangiocarcinoma

    PubMed Central

    Haga, Hiroaki; Patel, Tushar

    2015-01-01

    Intrahepatic cholangiocarcinomas (iCCA) are primary intrahepatic malignancies originating from biliary epithelia. While both hepatocellular cancer and iCCA can present as mass lesions within the liver, these cancers are distinct in their morphology, etiology, pathology, natural history and response to therapy. There is a need for accurate and sensitive molecular markers for the diagnosis of iCCA. Recent advances in elucidating molecular and genetic characteristics of iCCA offer the potential of molecular-based diagnosis of iCCA. Specific genetic mutations of IDH1/2, BAP1, p53, and KRAS, FGFR gene fusions and alterations in microRNA have all been described in iCCA. Although there are no accurate serum or biliary biomarkers currently available for diagnosis of iCCA, several potential candidates have been identified. Knowledge of specific genetic or molecular abnormalities offers potential for individualized approaches for the treatment of patients with iCCA in the future. PMID:25267595

  14. Molecular pathogenesis of intrahepatic cholangiocarcinoma.

    PubMed

    Andersen, Jesper B

    2015-02-01

    Cholangiocarcinoma (CCA) is an orphan cancer of the hepatobiliary tract, the incidence of which has increased in the past decade. The molecular pathogenesis of this treatment-refractory disease is poorly understood. Desmoplasia is a key causal feature of CCA; however, a majority of tumors develop with no apparent etiological background. The impact of the stromal compartment on tumor progression as well as resistance to therapy is in vogue, and the epithelial-stromal crosstalk may present a target for novel treatment strategies. As such, the complexity of tumor cellularity and the molecular mechanisms underlying the diversity of growth patterns of this malignancy remain a clinical concern. It is crucial to advance our present understanding of the molecular pathogenesis of CCA to improve current clinical strategies and patient outcome. This will facilitate the delineation of patient subsets and individualization for precision therapies. Many questions persevere as to the evolutionary process and cellular origin of the initial transforming event, the context of intratumoral plasticity and the causal driver action. Next-generation sequencing has begun to underline the persistent alterations, which may be the trigger of acquired drug resistance, and the cause of metastasis and disease recurrence. A complex issue that remains is to account for the heterogeneous pool of "backseat" aberrations, which in chromosomal proximity to the causative variant are likely to influence, for example, drug response. This review explores the recent advances in defining the molecular pathways implicated in the development of this devastating disease and, which present putative clinical strategies. PMID:25174625

  15. 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…

  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 detection technologies for arboviruses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arthropod-borne animal viruses (arboviruses) cause significant livestock and economic losses to world agriculture. This paper discusses the current and potential impact of these viruses, as well as the current and developing molecular diagnostic tools for these emerging and re-emerging insect transm...

  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. Targeted molecular imaging in oncology.

    PubMed

    Yang, David J; Kim, E Edmund; Inoue, Tomio

    2006-01-01

    Improvement of scintigraphic tumor imaging is extensively determined by the development of more tumor specific radiopharmaceuticals. Thus, to improve the differential diagnosis, prognosis, planning and monitoring of cancer treatment, several functional pharmaceuticals have been developed. Application of molecular targets for cancer imaging, therapy and prevention using generator-produced isotopes is the major focus of ongoing research projects. Radionuclide imaging modalities (positron emission tomography, PET; single photon emission computed tomography, SPECT) are diagnostic cross-sectional imaging techniques that map the location and concentration of radionuclide-labeled radiotracers. 99mTc- and 68Ga-labeled agents using ethylenedicysteine (EC) as a chelator were synthesized and their potential uses to assess tumor targets were evaluated. 99mTc (t1/2 = 6 hr, 140 keV) is used for SPECT and 68Ga (t1/2 = 68 min, 511 keV) for PET. Molecular targets labeled with Tc-99m and Ga-68 can be utilized for prediction of therapeutic response, monitoring tumor response to treatment and differential diagnosis. Molecular targets for oncological research in (1) cell apoptosis, (2) gene and nucleic acid-based approach, (3) angiogenesis (4) tumor hypoxia, and (5) metabolic imaging are discussed. Numerous imaging ligands in these categories have been developed and evaluated in animals and humans. Molecular targets were imaged and their potential to redirect optimal cancer diagnosis and therapeutics were demonstrated. PMID:16485568

  20. 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…

  1. 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

  2. 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.

  3. An invitation to molecular magnetism.

    PubMed

    Pinkowicz, Dawid; Chorazy, Szymon; Stefańczyk, Olaf

    2011-01-01

    Molecular magnetism is a new and extremely fascinating field on the borders of chemistry, physics and materials science. The design and synthesis of molecule-based magnets requires the chemist to exert considerable control over the molecules to arrange them appropriately. It also demands the development of new theories to explain the complex magneto-structural behaviour of these intriguing solids. Molecular magnetism is still at a very early stage of development. The main challenge is to increase the strength of the magnetic interactions between spin carriers so the resulting materials can be usable at room temperature. However molecular magnets exhibit true potential to become multifunctional materials. They show some considerable advantages over conventional magnets: optical transparency, chemical sensitivity and low weight to name just a few. The following article is not a complete review of the field. Its aim is rather to show how beautiful and versatile magnetic molecular solids can be, and to encourage the in-depth study of the subject. PMID:21805910

  4. Molecularly imprinted polymers for mycotoxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecularly imprinted polymers (MIPs) are a class of synthetic receptors capable of selective recognition of analytes. Recent developments in imprinting technology have made it possible to apply this technology in a range of applications, including mycotoxin detection. Structure-activity relations...

  5. Predicting Nonspecific Ion Binding Using DelPhi

    PubMed Central

    Petukh, Marharyta; Zhenirovskyy, Maxim; Li, Chuan; Li, Lin; Wang, Lin; Alexov, Emil

    2012-01-01

    Ions are an important component of the cell and affect the corresponding biological macromolecules either via direct binding or as a screening ion cloud. Although some ion binding is highly specific and frequently associated with the function of the macromolecule, other ions bind to the protein surface nonspecifically, presumably because the electrostatic attraction is strong enough to immobilize them. Here, we test such a scenario and demonstrate that experimentally identified surface-bound ions are located at a potential that facilitates binding, which indicates that the major driving force is the electrostatics. Without taking into consideration geometrical factors and structural fluctuations, we show that ions tend to be bound onto the protein surface at positions with strong potential but with polarity opposite to that of the ion. This observation is used to develop a method that uses a DelPhi-calculated potential map in conjunction with an in-house-developed clustering algorithm to predict nonspecific ion-binding sites. Although this approach distinguishes only the polarity of the ions, and not their chemical nature, it can predict nonspecific binding of positively or negatively charged ions with acceptable accuracy. One can use the predictions in the Poisson-Boltzmann approach by placing explicit ions in the predicted positions, which in turn will reduce the magnitude of the local potential and extend the limits of the Poisson-Boltzmann equation. In addition, one can use this approach to place the desired number of ions before conducting molecular-dynamics simulations to neutralize the net charge of the protein, because it was shown to perform better than standard screened Coulomb canned routines, or to predict ion-binding sites in proteins. This latter is especially true for proteins that are involved in ion transport, because such ions are loosely bound and very difficult to detect experimentally. PMID:22735539

  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. Distinción Empírica Entre Engagement y Trabajolismo en Enfermeras Hospitalarias de Japón: Efecto Sobre la Calidad del Sueño y el Desempeño Laboral

    PubMed Central

    Kubota, Kazumi; Shimazu, Akihito; Kawakami, Norito; Takahashi, Masaya; Nakata, Akinori; Schaufeli, Wilmar B.

    2016-01-01

    Objetivo El objetivo de este estudio es demostrar la distinción entre engagement y trabajolismo, estudiando su relación con la calidad del sueño y el desempeño laboral. Método Un total de 447 enfermeras de 3 hospitales de Japón fueron entrevistadas mediante un cuestionario autoadministrado que incluía la escala Utrecht (UWES, Utrecht Work Engagement Scale), la Escala de Adicción al Trabajo Holandesa (DUWAS, Dutch Workaholism Scale), preguntas sobre la calidad del sueño (7 ítems) con respecto a (1) dificultad para conciliar el sueño, (2) dificultad para mantener el sueño, (3) despertar temprano por la mañana, (4) dormirse o tomar siestas durante el día, (5) somnolencia diurna excesiva en el trabajo, (6) dificultad para despertarse por la mañana, y (7) despertar cansado en la mañana, y el Cuestionario sobre Salud y Desempeño (CSD) de la Organización Mundial de la Salud. Resultados Los modelos de ecuaciones estructurales demostraron que el engagement se relaciona positivamente con la calidad del sueño y el rendimiento laboral, mientras que el trabajolismo tiene una relación negativa con la calidad del sueño y el desempeño laboral. Conclusión Los resultados indican que el engagement y el trabajolismo son conceptualmente diferentes. El primero tiene una connotación positiva, mientras que el segundo se asocia de manera negativa al bienestar (buena calidad del sueño y buen rendimiento en el trabajo). PMID:26752805

  8. Huave de San Mateo del Mar, Oaxaca (Huave of San Mateo del Mar, Oaxaca).

    ERIC Educational Resources Information Center

    Mexico Coll. (Mexico City)

    This document is one of 17 volumes on indigenous Mexican languages and is the result of a project undertaken by the Archivo de Lenguas Indigenas de Mexico. This volume contains information on Huave, an indigenous language of Mexico spoken in San Mateo del Mar, in the state of Oaxaca. The objective of collecting such a representative sampling of…

  9. 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

  10. 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)

  11. 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.

  12. HTMD: High-Throughput Molecular Dynamics for Molecular Discovery.

    PubMed

    Doerr, S; Harvey, M J; Noé, Frank; De Fabritiis, G

    2016-04-12

    Recent advances in molecular simulations have allowed scientists to investigate slower biological processes than ever before. Together with these advances came an explosion of data that has transformed a traditionally computing-bound into a data-bound problem. Here, we present HTMD, a programmable, extensible platform written in Python that aims to solve the data generation and analysis problem as well as increase reproducibility by providing a complete workspace for simulation-based discovery. So far, HTMD includes system building for CHARMM and AMBER force fields, projection methods, clustering, molecular simulation production, adaptive sampling, an Amazon cloud interface, Markov state models, and visualization. As a result, a single, short HTMD script can lead from a PDB structure to useful quantities such as relaxation time scales, equilibrium populations, metastable conformations, and kinetic rates. In this paper, we focus on the adaptive sampling and Markov state modeling features. PMID:26949976

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

    PubMed Central

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

    2013-01-01

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

  14. 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

  15. 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. PMID:27010817

  16. 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

  17. Instantánea del sarcoma de Kaposi

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el sarcoma de Kaposi; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  18. Pastoral del Nino: Bringing the Abundant Life to Paraguayan Children

    ERIC Educational Resources Information Center

    Austin, Ann Berghout; Aquino, Cyle; Burro, Elizabeth

    2007-01-01

    Pastoral del Nino is transforming children's lives in rural Paraguay. Part of Pastoral Social (Catholic Social Services), Pastoral del Nino's primary focus is to bring "vida en abundancia" (the abundant life) to families by ensuring that mothers survive childbirth and children reach their first birthdays. In addition, the organization promotes…

  19. 75 FR 11104 - Del Norte Resource Advisory Committee (RAC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-10

    ... Forest Service Del Norte Resource Advisory Committee (RAC) AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Del Norte Resource Advisory Committee (RAC) will meet in Crescent City... and Designated Federal Official roles and (5) review operational guidelines; (6) selection of...

  20. Research and Evaluation Within the Del Mod System.

    ERIC Educational Resources Information Center

    Bolig, John R.

    Described is the Del Mod System, its inception, the fundings associated with it, and its objectives. A number of projects have already been completed and implemented. This monograph describes the evaluations of such projects and of the Del Mod systems-approach to science education. The area of evaluation and the method of data collection (with…

  1. 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...

  2. Instantánea del cáncer colorrectal

    Cancer.gov

    Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer colorrectal; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

  3. 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

  4. Molecular beam mass spectrometer development

    NASA Technical Reports Server (NTRS)

    Brock, F. J.; Hueser, J. E.

    1976-01-01

    An analytical model, based on the kinetics theory of a drifting Maxwellian gas is used to determine the nonequilibrium molecular density distribution within a hemispherical shell open aft with its axis parallel to its velocity. The concept of a molecular shield in terrestrial orbit above 200 km is also analyzed using the kinetic theory of a drifting Maxwellian gas. Data are presented for the components of the gas density within the shield due to the free stream atmosphere, outgassing from the shield and enclosed experiments, and atmospheric gas scattered off a shield orbiter system. A description is given of a FORTRAN program for computating the three dimensional transition flow regime past the space shuttle orbiter that employs the Monte Carlo simulation method to model real flow by some thousands of simulated molecules.

  5. Metallic, magnetic and molecular nanocontacts.

    PubMed

    Requist, Ryan; Baruselli, Pier Paolo; Smogunov, Alexander; Fabrizio, Michele; Modesti, Silvio; Tosatti, Erio

    2016-06-01

    Scanning tunnelling microscopy and break-junction experiments realize metallic and molecular nanocontacts that act as ideal one-dimensional channels between macroscopic electrodes. Emergent nanoscale phenomena typical of these systems encompass structural, mechanical, electronic, transport, and magnetic properties. This Review focuses on the theoretical explanation of some of these properties obtained with the help of first-principles methods. By tracing parallel theoretical and experimental developments from the discovery of nanowire formation and conductance quantization in gold nanowires to recent observations of emergent magnetism and Kondo correlations, we exemplify the main concepts and ingredients needed to bring together ab initio calculations and physical observations. It can be anticipated that diode, sensor, spin-valve and spin-filter functionalities relevant for spintronics and molecular electronics applications will benefit from the physical understanding thus obtained. PMID:27272139

  6. Driving Mechanisms for Molecular Outflows

    NASA Astrophysics Data System (ADS)

    Downes, Turlough P.

    Molecular outflows are observed to be closely associated with star formation. The cumulative momentum and the momentum injection rate in these outflows are important parameters in theories of star formation. The cumulative momentum in an outflow is a measure of the feed-back from star formation on molecular cloud turbulence. The level of turbulence in a cloud also effects the formation of further stars and, indeed, the survival of the cloud itself (e.g. [15]). In addition the rate of injection of momentum is an important constraint for theoretical models of outflows from young stars [10, 18]. Hence, while these outflows are interesting in themselves, it is also critical to understand their origin and behaviour as part of the general study of how stars themselves form.

  7. Molecular diagnostic tests for microsporidia.

    PubMed

    Ghosh, Kaya; Weiss, Louis M

    2009-01-01

    The Microsporidia are a ubiquitous group of eukaryotic obligate intracellular parasites which were recognized over 100 years ago with the description of Nosema bombycis, a parasite of silkworms. It is now appreciated that these organisms are related to the Fungi. Microsporidia infect all major animal groups most often as gastrointestinal pathogens; however they have been reported from every tissue and organ, and their spores are common in environmental sources such as ditch water. Several different genera of these organisms infect humans, but the majority of infections are due to either Enterocytozoon bieneusi or Encephalitozoon species. These pathogens can be difficult to diagnose, but significant progress has been made in the last decade in the development of molecular diagnostic reagents for these organisms. This report reviews the molecular diagnostic tests that have been described for the identification of the microsporidia that infect humans. PMID:19657457

  8. Molecular Approaches to Malaria 2000.

    PubMed

    Cowman, Alan F.; Cooke, Brian M.

    2000-04-01

    For more than 20 years now, Australia has been officially free of endemic malaria, but this devastating disease once again made a major impact on the continent in February 2000 when Melbourne hosted Australia's first major international conference on 'Molecular Approaches to Malaria' (Lorne, Australia, 2-5 February 2000). The global research effort toward our increased understanding of the pathogenesis and control of malaria in the post-genomics era was discussed and debated at length over 4 days packed with science encompassing molecular biology, cell biology, clinical studies, genomics, vaccines and pathogenic mechanisms. More than 260 researchers from 18 countries worldwide participated in this interdisciplinary meeting which comprised 57 oral presentations and 122 posters. Here we summarize some presentations pertinent to the field of drug action and resistance. Copyright 2000 Harcourt Publishers Ltd. PMID:11498369

  9. Molecular imaging in cervical cancer.

    PubMed

    Khan, Sairah R; Rockall, Andrea G; Barwick, Tara D

    2016-06-01

    Despite the development of screening and of a vaccine, cervix cancer is a major cause of cancer death in young women worldwide. A third of women treated for the disease will recur, almost inevitably leading to death. Functional imaging has the potential to stratify patients at higher risk of poor response or relapse by improved delineation of disease extent and tumor characteristics. A number of molecular imaging biomarkers have been shown to predict outcome at baseline and/or early during therapy in cervical cancer. In future this could help tailor the treatment plan which could include selection of patients for close follow up, adjuvant therapy or trial entry for novel agents or adaptive clinical trials. The use of molecular imaging techniques, FDG PET/CT and functional MRI, in staging and response assessment of cervical cancer is reviewed. PMID:26859085

  10. Symmetry breaking in molecular ferroelectrics.

    PubMed

    Shi, Ping-Ping; Tang, Yuan-Yuan; Li, Peng-Fei; Liao, Wei-Qiang; Wang, Zhong-Xia; Ye, Qiong; Xiong, Ren-Gen

    2016-07-11

    Ferroelectrics are inseparable from symmetry breaking. Accompanying the paraelectric-to-ferroelectric phase transition, the paraelectric phase adopting one of the 32 crystallographic point groups is broken into subgroups belonging to one of the 10 ferroelectric point groups, i.e. C1, C2, C1h, C2v, C4, C4v, C3, C3v, C6 and C6v. The symmetry breaking is captured by the order parameter known as spontaneous polarization, whose switching under an external electric field results in a typical ferroelectric hysteresis loop. In addition, the responses of spontaneous polarization to other external excitations are related to a number of physical effects such as second-harmonic generation, piezoelectricity, pyroelectricity and dielectric properties. Based on these, this review summarizes recent developments in molecular ferroelectrics since 2011 and focuses on the relationship between symmetry breaking and ferroelectricity, offering ideas for exploring high-performance molecular ferroelectrics. PMID:27051889

  11. 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

  12. 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

  13. Integration methods for molecular dynamics

    SciTech Connect

    Leimkuhler, B.J.; Reich, S.; Skeel, R.D.

    1996-12-31

    Classical molecular dynamics simulation of a macromolecule requires the use of an efficient time-stepping scheme that can faithfully approximate the dynamics over many thousands of timesteps. Because these problems are highly nonlinear, accurate approximation of a particular solution trajectory on meaningful time intervals is neither obtainable nor desired, but some restrictions, such as symplecticness, can be imposed on the discretization which tend to imply good long term behavior. The presence of a variety of types and strengths of interatom potentials in standard molecular models places severe restrictions on the timestep for numerical integration used in explicit integration schemes, so much recent research has concentrated on the search for alternatives that possess (1) proper dynamical properties, and (2) a relative insensitivity to the fastest components of the dynamics. We survey several recent approaches. 48 refs., 2 figs.

  14. Metallic, magnetic and molecular nanocontacts

    NASA Astrophysics Data System (ADS)

    Requist, Ryan; Baruselli, Pier Paolo; Smogunov, Alexander; Fabrizio, Michele; Modesti, Silvio; Tosatti, Erio

    2016-06-01

    Scanning tunnelling microscopy and break-junction experiments realize metallic and molecular nanocontacts that act as ideal one-dimensional channels between macroscopic electrodes. Emergent nanoscale phenomena typical of these systems encompass structural, mechanical, electronic, transport, and magnetic properties. This Review focuses on the theoretical explanation of some of these properties obtained with the help of first-principles methods. By tracing parallel theoretical and experimental developments from the discovery of nanowire formation and conductance quantization in gold nanowires to recent observations of emergent magnetism and Kondo correlations, we exemplify the main concepts and ingredients needed to bring together ab initio calculations and physical observations. It can be anticipated that diode, sensor, spin-valve and spin-filter functionalities relevant for spintronics and molecular electronics applications will benefit from the physical understanding thus obtained.

  15. Molecular dissociation in dilute gas

    SciTech Connect

    Renfrow, S.N.; Duggan, J.L.; McDaniel, F.D. |

    1999-06-01

    The charge state distributions (CSD) produced during molecular dissociation are important to both Trace Element Accelerator Mass Spectrometry (TEAMS) and the ion implantation industry. The CSD of 1.3{endash}1.7 MeV SiN{sup +}, SiMg{sup +}, SiMn{sup +}, and SiZn{sup +} molecules have been measured for elements that do not form atomic negative ions (N, Mg, Mn, and Zn) using a NEC Tandem Pelletron accelerator. The molecules were produced in a Cs sputter negative ion source, accelerated, magnetically analyzed, and then passed through an N{sub 2} gas cell. The neutral and charged breakups where analyzed using an electrostatic deflector and measured with particle detectors. Equilibrium CSD were determined and comparisons made between molecular and atomic ion data. {copyright} {ital 1999 American Institute of Physics.}

  16. 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. PMID:27073108

  17. 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.

  18. Molecular Diagnostic Tests for Microsporidia

    PubMed Central

    Ghosh, Kaya; Weiss, Louis M.

    2009-01-01

    The Microsporidia are a ubiquitous group of eukaryotic obligate intracellular parasites which were recognized over 100 years ago with the description of Nosema bombycis, a parasite of silkworms. It is now appreciated that these organisms are related to the Fungi. Microsporidia infect all major animal groups most often as gastrointestinal pathogens; however they have been reported from every tissue and organ, and their spores are common in environmental sources such as ditch water. Several different genera of these organisms infect humans, but the majority of infections are due to either Enterocytozoon bieneusi or Encephalitozoon species. These pathogens can be difficult to diagnose, but significant progress has been made in the last decade in the development of molecular diagnostic reagents for these organisms. This report reviews the molecular diagnostic tests that have been described for the identification of the microsporidia that infect humans. PMID:19657457

  19. 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

  20. 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.

  1. Infrared molecular emissions from comets

    NASA Technical Reports Server (NTRS)

    Weaver, H. A.; Mumma, M. J.

    1983-01-01

    The possibility of detecting IR molecular line emission from cometary parent molecules is explored. Due to the non-LTE conditions in the inner coma and the large amount of near IR solar flux, IR fluorescence will be a significant source of cometary emission and, in fact, will dominate the grain radiation in a sufficiently high resolution instrument. The detection of this line emission will be difficult due to absorption in the terrestrial atmosphere, but it appears possible to measure cometary H2O emission from airplane altitudes. As IR molecular line emission represents one of the few promising methods of detecting cometary parent molecules directly, further research on this problem should be vigorously pursued.

  2. Exciton coupling in molecular crystals

    NASA Technical Reports Server (NTRS)

    Ake, R. L.

    1976-01-01

    The implications of perfect exciton coupling and molecular vibrations were investigated, as well as the effect they have on the lifetime of singlet and triplet excitons coupled in a limiting geometry. Crystalline bibenzyl, Cl4Hl4, provided a situation in which these mechanisms involving exciton coupling can be studied in the limit of perfect coupling between units due to the crystal's geometry. This geometry leads to a coupling between the two halves of the molecule resulting in a splitting of the molecular excited states. The study reported involves an experimental spectroscopic approach and begins with the purification of the bibenzyl. The principal experimental apparatus was an emission spectrometer. A closed cycle cryogenic system was used to vary the temperature of the sample between 20 K and 300 K. The desired results are the temperature-dependent emission spectra of the bibenzyl; in addition, the lifetimes and quantum yields measured at each temperature reveal the effect of competing radiationless processes.

  3. Molecular Mechanism of TRP Channels

    PubMed Central

    Zheng, Jie

    2013-01-01

    Transient receptor potential (TRP) channels are cellular sensors for a wide spectrum of physical and chemical stimuli. They are involved in the formation of sight, hearing, touch, smell, taste, temperature, and pain sensation. TRP channels also play fundamental roles in cell signaling and allow the host cell to respond to benign or harmful environmental changes. As TRP channel activation is controlled by very diverse processes and, in many cases, exhibits complex polymodal properties, understanding how each TRP channel responds to its unique forms of activation energy is both crucial and challenging. The past two decades witnessed significant advances in understanding the molecular mechanisms that underlie TRP channels activation. This review focuses on our current understanding of the molecular determinants for TRP channel activation. PMID:23720286

  4. 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

  5. [Molecular imaging in neurological diseases].

    PubMed

    Reimold, M; la Fougère, C

    2016-07-01

    In neurodegeneration and in neuro-oncology, the standard imaging procedure, magnetic resonance imaging (MRI), shows limited sensitivity and specificity. Molecular imaging with specific positron-emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers allows various molecular targets and metabolic processes to be assessed and is thus a valuable adjunct to MRI. Two important examples are referred to here: amino acid transport for neuro-oncological issues, and the recently approved PET tracers for detecting amyloid depositions during the preclinical stage of Alzheimer's disease. This review discusses the clinical relevance and indications for the following nuclear medicine imaging procedures: amyloid PET, (18)F-fluorodeoxyglucose (FDG)-PET, and dopamine transporter (DaT)-SPECT for the diagnosis of dementia and the differential diagnosis of Parkinson's disease, in addition to amino acid PET for the diagnosis of brain tumors and somatostatin receptor imaging in meningioma. PMID:27306201

  6. Molecular abnormalities in Ewing's sarcoma.

    PubMed

    Burchill, Susan Ann

    2008-10-01

    Ewing's sarcoma is one of the few solid tumors for which the underlying molecular genetic abnormality has been described: rearrangement of the EWS gene on chromosome 22q12 with an ETS gene family member. These translocations define the Ewing's sarcoma family of tumors (ESFT) and provide a valuable tool for their accurate and unequivocal diagnosis. They also represent ideal targets for the development of tumor-specific therapeutics. Although secondary abnormalities occur in over 80% of primary ESFT the clinical utility of these is currently unclear. However, abnormalities in genes that regulate the G(1)/S checkpoint are frequently described and may be important in predicting outcome and response. Increased understanding of the molecular events that arise in ESFT and their role in the development and maintenance of the malignant phenotype will inform the improved stratification of patients for therapy and identify targets and pathways for the design of more effective cancer therapeutics. PMID:18925858

  7. 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.

  8. 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.

  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 Genetics of Tooth Development

    PubMed Central

    Bei, Marianna

    2009-01-01

    Organogenesis depends upon a well-ordered series of inductive events involving coordination of molecular pathways that regulate the generation and patterning of specific cell types. Key questions in organogenesis involve the identification of the molecular mechanisms by which proteins interact to organize distinct pattern formation and cell fate determination. Tooth development is an excellent context for investigating this complex problem because of the wealth of information emerging from studies of model organisms and human mutations. Since there are no obvious sources of stem cells in adult human teeth, any attempt to create teeth de novo will likely require the re-programming of other cell types. Thus, the fundamental understanding of the control mechanisms responsible for normal tooth patterning in the embryo will help us understand cell fate specificity and may provide valuable information towards tooth organ regeneration. PMID:19875280

  11. Double Potoionization of Molecular Hydrogen

    NASA Astrophysics Data System (ADS)

    Vanroose, Wim

    2006-05-01

    We report a complete numerical solution of the Schr"odinger equation for the double photoionization of H2, a process where a single photon emits two electrons. The results suggest that the distribution of photoelectrons emitted from aligned molecules reflects electron correlation effects that are purely molecular in origin. It confirms recent experimental results in experiments on oriented hydrogen molecules. These experiments observed that the ejection pattern of the electrons depends sensitively on the bond distance between the two nuclei as well as the orientation with respect to the polarization of the photon. We give an overview of the numerical methods we used to solve the exact Schrodinger equation for this problem. We also discuss the different molecular effect we observe in our calculations and compare with experimental observations

  12. 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.

  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. Isolation of Sphaerotilus-Leptothrix strains from iron bacteria communities in Tierra del Fuego wetlands.

    PubMed

    Schmidt, Bertram; Sánchez, Leandro A; Fretschner, Till; Kreps, Gastón; Ferrero, Marcela A; Siñeriz, Faustino; Szewzyk, Ulrich

    2014-11-01

    Sheath-forming iron- and manganese-depositing bacteria belonging to the Sphaerotilus-Leptothrix group (SLG) are widespread in natural and artificial water systems. Known requirements for their growth include the presence of organic substrates and molecular oxygen. High concentrations of reduced iron or manganese, although not necessary for most species, make their growth a noticeable phenomenon. Such microbial communities have been studied mostly in the Northern Hemisphere. Here, we present descriptions of diverse ochre-depositing microbial communities in Tierra del Fuego, Argentina, using a combined approach of microscopical examination, clone library construction and cultivation focused on SLG bacteria. To date, only few SLG type strains are available. The present work increases the number and diversity of cultivated SLG bacteria by obtaining isolates from biofilms and sediment samples of wetlands in Tierra del Fuego. Thirty isolates were selected based on morphological features such as sheath formation and iron/manganese deposition. Five operational taxonomic units (OTUs) were deduced. Sequencing of 16S rRNA genes showed that one OTU is identical to the Leptothrix mobilis Feox-1(T) -sequence while the four remaining OTUs show similarity values related to previously described type strains. Similarity values ranged from 96.5% to 98.8%, indicating possible new species and subspecies. PMID:25098830

  15. Molecular Analyses of Transgenic Plants.

    PubMed

    Trijatmiko, Kurniawan Rudi; Arines, Felichi Mae; Oliva, Norman; Slamet-Loedin, Inez Hortense; Kohli, Ajay

    2016-01-01

    One of the major challenges in plant molecular biology is to generate transgenic plants that express transgenes stably over generations. Here, we describe some routine methods to study transgene locus structure and to analyze transgene expression in plants: Southern hybridization using DIG chemiluminescent technology for characterization of transgenic locus, SYBR Green-based real-time RT-PCR to measure transgene transcript level, and protein immunoblot analysis to evaluate accumulation and stability of transgenic protein product in the target tissue. PMID:26614292

  16. Molecular Mechanisms of Arterial Stiffening

    PubMed Central

    Cecelja, Marina; Chowienczyk, Phil

    2016-01-01

    Stiffening of large arteries is a hallmark of vascular aging and one of the most important determinants of the age-related increase in blood pressure and cardiovascular disease events. Despite a substantial genetic component, the molecular mechanisms underlying phenotypic variability in arterial stiffness remain unknown. Previous genetic studies have identified several genetic variants that are associated with measures of arterial stiffness. Here, we review the relevant advances in the identification of pathways underlying arterial stiffness from genomic studies. PMID:27493903

  17. [Molecular diagnosis of primary immunodeficiencies].

    PubMed

    García Rodríguez, M C; López Granados, E; Cambronero Martínez, R; Ferreira Cerdán, A; Fontán Casariego, G

    2001-01-01

    Knowledge of the molecular defects responsible for some primary immunodeficiency diseases (PIDs) offers undoubted advantages in establishing a reliable diagnosis. Such knowledge would allow us not only to establish a prognosis but also to instigate the most appropriate therapy. After molecular diagnosis, some patients could benefit from gene therapy. However, apart from the diagnosis of the disease, molecular biological techniques also enable more reliable identification of carriers and, when suggested by the family history and when the familial defect is already known, prenatal diagnosis will also be possible, thus establishing the earliest possible treatment. Using the single-stranded conformational polymorphism technique followed by direct sequencing, we found 22 different mutations in 22 patients from unrelated families and with a phenotype compatible with x-linked agammaglobulinemia. Fourteen of these are new, previously undescribed mutations and the remaining eight are already included in the data base (http://www.uta.fi/imt/bioinfo/Btkbase). Analysis of the female carrier was performed in all the mothers and the mutation was de novo in only one patient. Study of the BtK gene enabled differential diagnosis with common variable immunodeficiency disease in some patients who showed absent or very low lymphocyte B counts as well as forms of autosomal recessive agammaglobulinemia. Using the same techniques, we were able to identify mutations in the CD40 ligand gene in three families in which one of the members had clinical and biological phenotype compatible with X-linked hyper-IgM. Molecular diagnosis was very useful in identifying carriers in these families as well as in making the differential diagnosis among patients with common variable immunodeficiency disease. Purely on this were we able to provide appropriate genetic counseling. PMID:11434883

  18. EAACI Molecular Allergology User's Guide.

    PubMed

    Matricardi, P M; Kleine-Tebbe, J; Hoffmann, H J; Valenta, R; Hilger, C; Hofmaier, S; Aalberse, R C; Agache, I; Asero, R; Ballmer-Weber, B; Barber, D; Beyer, K; Biedermann, T; Bilò, M B; Blank, S; Bohle, B; Bosshard, P P; Breiteneder, H; Brough, H A; Caraballo, L; Caubet, J C; Crameri, R; Davies, J M; Douladiris, N; Ebisawa, M; EIgenmann, P A; Fernandez-Rivas, M; Ferreira, F; Gadermaier, G; Glatz, M; Hamilton, R G; Hawranek, T; Hellings, P; Hoffmann-Sommergruber, K; Jakob, T; Jappe, U; Jutel, M; Kamath, S D; Knol, E F; Korosec, P; Kuehn, A; Lack, G; Lopata, A L; Mäkelä, M; Morisset, M; Niederberger, V; Nowak-Węgrzyn, A H; Papadopoulos, N G; Pastorello, E A; Pauli, G; Platts-Mills, T; Posa, D; Poulsen, L K; Raulf, M; Sastre, J; Scala, E; Schmid, J M; Schmid-Grendelmeier, P; van Hage, M; van Ree, R; Vieths, S; Weber, R; Wickman, M; Muraro, A; Ollert, M

    2016-05-01

    The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients. PMID:27288833

  19. An antilock molecular braking system.

    PubMed

    Sun, Wei-Ting; Huang, Shou-Ling; Yao, Hsuan-Hsiao; Chen, I-Chia; Lin, Ying-Chih; Yang, Jye-Shane

    2012-08-17

    A light-driven molecular brake displaying an antilock function is constructed by introducing a nonradiative photoinduced electron transfer (PET) decay channel to compete with the trans (brake-off) → cis (brake-on) photoisomerization. A fast release of the brake can be achieved by deactivating the PET process through addition of protons. The cycle of irradiation-protonation-irradiation-deprotonation conducts the brake function and mimics the antilock braking system (ABS) of vehicles. PMID:22853709

  20. Molecular aspects of charm physics

    SciTech Connect

    Fernandez, F.; Ortega, P. G.; Entem, D. R.

    2013-03-25

    We study the influence of possible molecular structures in the charmonium spectrum. We focus on the 0{sup ++}, 1{sup ++} and 1{sup --} sectors. In the first one we coupled the 2{sup 3}P{sub 0}cc pair with DD, J/{psi}{omega}, D{sub s}D{sub s} and J/{psi}{phi} channels and we obtain two states compatibles with the X(3945) and the Y(3940). In the second one we couple the 2{sup 3}P{sub 1}cc state with the DD{sup *} channel and we obtain a dressed state compatible with the X(3940) and a new state that we assign to the X(3872). In the third one we include the 3{sup 3}S{sub 1} and 2{sup 3}D{sub 1} charmonium states coupled to DD, DD{sup *}, D{sup *}D{sup *}, D{sub s}D{sub s}, D{sub s}D{sup *}s and D{sup *}{sub s}D{sup *}{sub s}. In this calculation we obtain a new molecular state that could be the G(3900) or the controversial Y(4008) and two cc states dressed by the molecular components assigned to the {psi}(4040) and the {psi}(4160). Finally we perform a calculation in the five quark sector where we can describe the {Lambda}{sub c}(2940){sup +} as a ND{sup *} molecular state and predict a {Lambda}{sub b}(6248){sup +} state.