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Sample records for c71 dot bien

  1. Noam Chomsky, Le bien commun

    OpenAIRE

    Ferrand, Laure

    2014-01-01

    Le bien commun regroupe une série d’entretiens réalisés par le journaliste américain David Barsamian avec Noam Chomsky. Ils traitent essentiellement de l’approche politique et critique de Chomsky à travers les différents écrits qu’il a publiés et les conférences qu’il a données. Ainsi, nous retrouvons dans cet ouvrage les questions principales qui irriguent la pensée de l’auteur : l’économie capitaliste est-elle synonyme de liberté ? Les États-Unis - et plus largement les pays se caractérisan...

  2. Embargo de bienes y sociedad de gananciales

    OpenAIRE

    Gascón Inchausti, Fernando

    2001-01-01

    El trabajo contiene un análisis jurisprudencial de las dificultades dogmáticas y prácticas que genera el embargo de bienes pertenecientes a personas físicas casadas bajo el régimen económico de gananciales. Se distingue en función de si la deuda nació estando vigente la sociedad de gananciales o una vez disuelta, y también, por supuesto, en función del carácter privativo o ganancial del bien y de la deuda en virtud de la cual se ha despachado la ejecución.

  3. Estrategias para aprender a pensar bien

    OpenAIRE

    Monereo i Font, Carles,

    1995-01-01

    El autor explica con cierto detalle qué significa aprender a pensar bien y cómo hacer un uso apropiado del conocimiento que los alumnos poseen. En este sentido, expone algunas premisas, estrategias y procedimientos que contribuyen a ello.

  4. A two-directional synthesis of the C58-C71 fragment of palytoxin.

    Science.gov (United States)

    Hodgson, Robert; Nelson, Adam

    2004-02-01

    A two directional approach, in which asymmetric dihydroxylation and reduction reactions were used to control absolute configuration, was exploited in the preparation of a C(2)-symmetrical dipyranone. The homotopic dihydropyran (DHP) rings of this precursor were differentiated statistically using by a Prevost reaction and further functionalisation. A second Prevost reaction was used to functionalise the other DHP; global deprotection and peracetylation gave a protected version of the C(58)-C(71) fragment of palytoxin. Methods which might be of value in future synthetic work were developed for the stereoselective functionalisation of THP rings similar to those found in this fragment.

  5. El arte de vivir bien y dignamente

    Directory of Open Access Journals (Sweden)

    Aguinaga Benítez Oscar William

    1997-11-01

    Full Text Available

    Por tradición y a diferencia de otras culturas, nos han enseñado en la casa, escuela o colegio y mucho más en el trabajo a buscar amor, prosperidad, salud, felicidad y satisfacción en el exterior y jamás se nos ha hecho ver, ni se nos ha inculcado que la mayor riqueza está en el interior de cada uno de nosotros. Bien dice el doctor Dyer "se nos ha condicionado para creer que recibimos la gracia de la vida" y no para que disfrutemos de la inmortalidad de nuestro yo espiritual, se niega la opción de estar siempre acompañado de una energía que para muchos es lo divino y para otros es la conciencia.

  6. Modelización de los Bienes Públicos

    Directory of Open Access Journals (Sweden)

    Juan Carlos Aguado Franco

    2014-02-01

    Full Text Available En el contexto de los bienes públicos es bien conocida la posibilidad de que surja una ineficiencia económica debida a que los individuos puedan verse tentados a actuar como “free-riders”, mostrando una nula disposición a pagar, con la esperanza de que, si ese bien o servicio termina siendo suministrado a un individuo que lo pague, los demás van a poder disfrutarlo igualmente sin incurrir en ningún coste. Si todo el mundo obrase de esa manera, sin embargo, el bien público finalmente no sería suministrado para nadie, disminuyendo el bienestar de los interesados, salvo que el Estado decidiera hacerse cargo de su provisión. Aunque la comprensión de este planteamiento es inmediata, la plasmación en un modelo de esta realidad, sin embargo, no es tan sencilla. Así, dependerá de los supuestos adicionales que realicemos, tanto de la función de producción del bien público (véase al respecto por ejemplo, Sandler, 1992; Marwell y Oliver, 1993; Heckathorn, 1996 o Kollock, 1998 como de la interrelación existente entre los individuos interesados, lo que nos llevará a la consideración de distintos dilemas, como, entre otros, el del voluntario o el del altruista (Diekman, 1985; Rapoport, 1988; Heckathorn, 1991; Weesie, 1993; Goetze, 1994; Weesie, 1994. En este trabajo se examina la conveniencia de la aplicación de unos u otros modelos en función de las circunstancias presentes en cada caso particular. Palabras clave: bienes públicos, dilemas sociales.

  7. Propriété, biens publics mondiaux, bien(s commun(s : Une lecture des concepts économiques

    Directory of Open Access Journals (Sweden)

    Jérôme Ballet

    2008-03-01

    Full Text Available La notion de bien public mondial s’est développée ces dernières années. Elle renvoie à un dépassement ambigu de la notion usuelle dans la théorie économique de bien public. A cette occasion elle ouvre le débat sur l’équité en complément de l’efficience. De ce fait, la confrontation de cette nouvelle notion avec l’analyse de l’efficience des régimes de propriété s’impose. Par ailleurs, la confrontation avec la notion de bien commun, notion elle aussi en développement, éclaire l’enjeu autour de l’équité.Property, Global Public Goods, Common Good(s : A Lecture. The concept of global public good emerged these last years. It proposes, in an ambiguous way, to go beyond the usual concept of public good. Then, added to usual questions on efficiency, the debate on fairness becomes a stake. Confrontation with analysis on property rights command attention, Furthermore, confrontation with the concept of common good, also a developing concept, highlight stake around fairness.

  8. CONTROL DE INVENTARIO DE BIENES MUEBLES EN LA GERENCIA REGIONAL DE SALUD, AREQUIPA, 2010

    OpenAIRE

    REVILLA VELA, DELFINA LUISA

    2014-01-01

    VERIFICACIÓN EN EL CONTROL DE INVENTARIOS BIENES MUEBLES VERIFICACIÓN DE LA TASACIÓN EN EL CONTROL DE INVENTARIOS BIENES MUEBLES VERIFICACIÓN DE LA CODIFICACIÓN EN EL CONTROL DE INVENTARIOS BIENES MUEBLES VERIFICACIÓN DEL ETIQUETADO EN EL CONTROL DE INVENTARIOS BIENES MUEBLES VERIFICACIÓN DE LA REGULARIZACIÓN EN EL CONTROL DE INVENTARIOS BIENES MUEBLES VERIFICACIÓN DE LA CONCILIACIÓN EN EL CONTROL DE INVENTARIOS BIENES MUEBLES APRECIACIÓN GLOBAL SOBRE EL CONTROL DE INVENTARIO DE BIENES MUEBLE...

  9. Industrias de bienes de consumo buscan el éxito

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    José Ernesto Ramírez

    1987-04-01

    Full Text Available Requerimientos críticos para el éxito competitivo de las empresas, cuando se desarrolla su sistema de negocios: El caso de industrias seleccionadas de bienes de consumo en Colombia. Joseph Ganitsky Brandwayn. (Tesis de doctorado, Harvard University, School of Business Administration, 1974 University Microfilm International. Ann Arbor (Michigan. 1983, 317 páginas; 28 cuadros, 4 apéndices. (Disponible en la Biblioteca Luis Angel Arango.

  10. "Bien Común" base del desarrollo de las organizaciones

    OpenAIRE

    2007-01-01

    Texto correspondiente a la Clausura del Curso de Desarrollo Directivo de la Universidad de Alcalá El papel de la Universidad es orientarse al desarrollo de la persona y de su futuro. Y ello tiene lugar dentro de comunidades, corporaciones, empresas en las que su éxito depende de la capacidad individual y social de la creación de ¿bien común¿, que permite generar las bases para compartir. Sólo cuando hay una base compartida, este es el intangible por excelencia, pueden con...

  11. Outbreak of bullous impetigo caused by Staphylococcus aureus strains of phage type 3C/71 in a maternity ward linked to nasal carriage of a healthcare worker.

    Science.gov (United States)

    Piechowicz, Lidia; Garbacz, Katarzyna; Budzyńska, Anna; Dąbrowska-Szponar, Maria

    2012-01-01

    We describe an outbreak of bullous impetigo (BI) that occurred in a maternity unit and show phenotypic and genotypic properties and relatedness of isolated Staphylococcus aureus strains. Clinical material was obtained from 11 affected neonates. Additionally, nasal swabs from 67 healthy care workers (HCWs) as well as 107 environmental swabs were investigated. All isolates were screened for exfoliative toxin genes (eta, etb), antibiotic susceptibility and phage typed. Chromosomal DNA was genotyped by MLVF method and PCR/RFLP of coagulase gene were tested. Affected neonates were infected by two clusters of eta-positive S. aureus of phage type 3C/71: (1) MLVF type A isolates resistant only to penicillin, and (2) MLVF type B isolates resistant to penicillin and erythromycin/clindamycin. All isolates were susceptible to methicillin. We found 19 of 67 HCWs to be S. aureus nasal carriers. Two nasal isolates from HCWs were related to the outbreak on the basis of phage typing, PCR detection of eta/etb genes, antibiotyping and genotyping. Additionally, environmental swabs from the maternity unit revealed a 3C/71 S. aureus in the mattress of a baby bed. This is the first documented case of an outbreak of BI caused by phage type 3C/71 eta-positive strain of S. aureus.

  12. La desprotección de bienes culturales: Enajenación de bienes públicos; la descatalogación

    OpenAIRE

    Bermúdez Sánchez, Javier

    2015-01-01

    En principio la enajenación de bienes culturales de las Administraciones públicas está expresamente prohibida. Sin embargo, se ha planteado la posibilidad de descatalogar los bienes para proceder a continuación a su enajenación. La jurisprudencia es muy restrictiva al respecto, dado que califica como actuación reglada de la Administración el dejar sin efectos la catalogación de los bienes culturales, como asimismo la catalogación. A partir de la regulación y jurisprudencia solo...

  13. Los bienes comunes intangibles en el capitalismo cognitivo.

    Directory of Open Access Journals (Sweden)

    Álvaro Ramis Olivos

    2014-10-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 Este texto analizará críticamente la actual fase económica para mostrar la importancia de los bienes comunes intangibles. Sondea la tesis de un nuevo modo de producción «en ciernes», basado en la gestión colaborativa. Analiza los intangibles de acuerdo a su calidad y carácter. Compara los sistemas de patentes y derechos de propiedad intelectual que permiten su apropiación y las resistencias a su «comoditización» desde el software libre y las propuestas de flexibilización de derechos de autor. Advierte sobre el «fetichismo tecnológico» y propone un marco mínimo de discernimiento en dilemas vinculados a estas materias. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

  14. Flaring Activity from S5 0836+71 (4C71.07): What Can We Learn with Limited Multiwavelength Coverage?

    Science.gov (United States)

    Thompson, D. J.; Donato, D.; Akyuz, A.; Fuhrmann, L.; Sokolovsky, K.; Kurtanidze, O.

    2011-01-01

    After a long period of quiescence in gamma rays, blazar S5 0836+71 (4C71.07) flared in the Spring of 2011. We found only limited multiwavelength coverage of the source. An indication of correlated optical/gamma-ray variability is not surprising for a FSRQ like this one. Radio observations at high frequencies, however, had seen a flare in late 2010, with no apparent related gamma-ray activity. This case seems to differ from the traditional pattern of finding gamma-ray flares during times of rising radio emission.

  15. Ciberciudadanía, cultura y bienes públicos

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    Álvarez, J. Francisco

    2009-06-01

    Full Text Available Net society is provoking dramatic changes in several aspects of our daily life as cultural traits, business and the more disparages spheres of privacy and social life. We must attend both to freedom of access and to new services generation because of the peculiar form public goods are raising in the Net. To supersede individual capability limitations and to diffuse digital and cultural gaps, electronic government could be a cultural decisive tool in this phase of cibersociety enhancement. Technologies enhanced the human capabilities, as well as with the social actions and its framework, including cultural production and management. Technologies are also transforming the generation, reproduction and transmission of (social knowledge.La sociedad red transforma la vida cotidiana, las diversas manifestaciones culturales, los negocios, las esferas más diversas de la vida privada y social. La forma en que se generan los bienes públicos en la red exige una preocupación explícita por la libertad de acceso y la generación de nuevos servicios, que ayuden a superar limitaciones de los individuos y faciliten desdibujar las diversas brechas digitales y ciberculturales. El gobierno electrónico resulta culturalmente decisivo en esta fase de expansión de la cibersociedad. Las tecnologías amplían las capacidades humanas, expanden el espacio y las formas de acción social, incluidas la producción y gestión cultural. También producen cambios en las formas de generación, reproducción y transmisión del conocimiento (social.

  16. Economía institucional de un bien mayor

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    Óscar A. Alfonso Roa

    2007-12-01

    Full Text Available La provisión de los servicios de acueducto y alcantarillado en Colombia ha sido sometida, desde 1994, a una terapia consistente en la promoción de un modelo empresarial que se abre paso a costa de la estigmatización del municipio como mal prestador y como asignador ineficiente de unos recursos escasos. a quince años de operación del modelo empresarial y en desarrollo del Acto Legislativo 04 de 2007, el Gobierno nacional ha introducido otra reforma, en esta oportunidad al Sistema General de Participaciones, esgrimiendo en la exposición de motivos los mismos argumentos de antaño, cuando en verdad mediante la prestación directa de los municipios sólo se provee de estos servicios a una porción minoritaria de la población urbana del país. En la primera parte se discute la noción del agua potable como bien mayor y en la segunda se presenta una breve síntesis de la evolución institucional de la provisión del agua potable en colombia. en la tercera parte se discuten algunos rasgos centrales del proceso de urbanización de la población colombiana a la que se sirve con el servicio de acueducto mientras que en la última se analiza la coyuntura reciente con énfasis en la crítica a la reforma introducida por el acto Legislativo 04 de 2007. este artículo propone otros puntos de vista para criticar, además de la reforma en curso, las fallas de un esquema de provisión cifrado en un enfoque empresarial sometido a una inocua regulación, que no logra conciliar los intereses de ampliación de las ganancias de las empresas de servicios públicos con las aspiraciones sociales en materia de universalización y calidad de los servicios de acueducto y alcantarillado.

  17. Bien común y ética pública: Alcances y límites del concepto tradicional de bien común

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    Dorando J. Michelini

    2007-12-01

    Full Text Available Con el concepto de bien común se ha hecho referencia, a través de la historia, a aquellos bienes materiales e inmateriales que no se circunscriben a una persona sino que remiten a todos y cada uno de los miembros de la sociedad. Entre esos bienes suelen contarse elementos básicos para la supervivencia humana biológica, como el aire y el agua, pero también el derecho a participar en el usufructo de los bienes de la cultura. En algunos casos, el bien común es equiparado al bienestar general; en otros, a la suma de intereses particulares o al beneficio de la mayoría, como cuando se busca el mayor bien para el mayor número posible de individuos. Más allá de las diversas interpretaciones, la promoción del bien común sigue siendo en la actualidad un objetivo clave del Estado en el ideario democrático y un tema recurrente de la ética pública. En lo que sigue, se reconstruye críticamente el concepto tradicional de bien común, haciendo especial referencia a las obras de Platón, Aristóteles y Santo Tomas, con el fin de sentar bases para una nueva comprensión de la idea de bien común en sociedades pluralistas y democráticas.With the concept of commom good reference has been made, along history, to those material and immaterial goods which are not circumscribed to a person, but remit to each and every member of society. Among those goods, basic elements for biological human survival, such as air and water, are usually included, but also the right to participate of the profits of cultural goods. In some cases, commom good has been made equivalent to common wellfare; in others, to the summation of particular interests or to the benefit of the majority. Beyond the diverse interpretations, the promotion of common good continues at present to be a key aim of State in the democratic ideary and a recurrent issue in public ethics. In what follows, the concept of traditional common good has been reconstructed, making special reference to the

  18. "Vivir Bien" y pobreza multidimensional. ¿Es posible una conciliación conceptual?

    OpenAIRE

    Ahmed Eid; Javier Aliaga Lordemann

    2013-01-01

    Este documento explica cómo el concepto de Vivir Bien constituye un paradigma prevalente, no estructurado en todos los niveles paradigmáticos, lo que hace que no pueda considerarse como un paradigma de desarrollo sincrético y global. Además, los autores encuentran que si bien existe un vínculo entre el enfoque de capacidades y el concepto de Vivir Bien, una medición de éste, via un indicador de pobreza multidimensional, no es posible, dadas las complejidades intrínsecas en la postulación de u...

  19. Bien écrire en affaires savoir rédiger pour être lu et convaincre

    CERN Document Server

    Berrou, Jean-Paul

    1991-01-01

    Ce qu'il faut savoir pour bien rédiger ses écrits professionnels au travers d'une démarche méthodique pour bien organiser sa pensée en vue d'écrire efficacement, de conseils et de techniques pour être compris à coup sûr et être lu jusqu'au bout avec intérêt. Agrémenté de nombreux exemples concrets.

  20. Swift multi-wavelength observations of the high-redshift Blazar S5 0836+710 (4C 71.07)

    Science.gov (United States)

    Vercellone, Stefano; Romano, Patrizia; Raiteri, Claudia Maria; Acosta Pulido, Jose; Villata, Massimo; Carnerero Martin, Maria Isabel

    2016-04-01

    We present the preliminary results of a year-long Swift monitoring campaign of the high-redshift (z=2.172) flat-spectrum radio quasar (FSRQ) S5 0836+710 (4C 71.07). The campaign, based on one observation per month, 5 ks each observation, for 12 months, allowed us to investigate the synchrotron and nuclear emission contributions to the optical-UV frequency range of its spectral energy distribution and the X-ray spectral variations along a baseline of a year. We obtained a high-accuracy determination of UVOT magnitudes, an X-ray photon index with an uncertainty of the order of 5%, and well-sampled light curves both in the optical-UV and X-ray energy bands to study their possible modulations and correlations. Our study allowed us to exploit the unique Swift capabilities in terms of both simultaneous energy coverage and schedule flexibility. The Swift monitoring campaign was supported by observations by the GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) Collaboration, which provided radio, near-infrared, and optical photometric data as well as optical polarimetry. Moreover, a spectroscopic monitoring was obtained at the William Herschel Telescope (WHT) and the Nordic Optical Telescope (NOT). All these observations will allow us to obtain a comprehensive picture of the jet as well as of the nuclear source emission.

  1. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    Semiconductor quantum dots ("solid-state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra. Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dot states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  2. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    1999-01-01

    Semiconductor quantum dots ("solid state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra.Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dots states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  3. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...... and Middleton, 1995). A reminiscence conversation is a dynamic talk-in-interaction, which can produce valuable learning experience for the participants involved. Reminiscence talk contains rich, personal, historic data that can reveal and inform family members of an unknown past. In this seminar/chapter, we...... shall present a discursive approach, a methodology that captures the dynamics of reminiscence. We analyse collected conversational data of British family members reminiscing on their past as a joint family activity. Through such talk-in-interaction, the family members develop continuity within...

  4. TRASMISIÓN DE BIENES Y REGISTRO DE LA PROPIEDAD EN ESPAÑA (SEGUNDA PARTE

    Directory of Open Access Journals (Sweden)

    Joaquín Sánchez Cebrián

    2009-01-01

    Full Text Available La circulación de los bienes en el tráfico jurídico por la voluntad de los particulares es un tema crucial que interesa, no sólo a las partes del contrato, sino, a todos en general, y, en particular, a los acreedores del transmitente o del adquirente y a los terceros adquirentes de derechos sobre el bien. En este trabajo se analizará el régimen de trasmisión de los bienes por negocio inter vivos en el Derecho español, dentro del marco europeo, y con particular referencia a la trasmisión inmobiliaria. España adopta un peculiar sistema de trasmisión de los bienes porque se establecen reglas genéricas cuya aplicación se da con independencia de la naturaleza mueble o inmueble del bien; pero a su lado se superponen otras que tratan de fijar los efectos de la publicidad registral inmobiliaria. La coordinación entre dichas reglas produce un original resultado, que puede constituir el punto de encuentro de los diversos sistemas registrales europeos.

  5. Bienes públicos y cooperación regional para el desarrollo : Una nueva mirada

    OpenAIRE

    Sandler, Todd

    2013-01-01

    En el presente artículo se ofrece un nuevo enfoque sobre los bienes públicos y el papel que desempeñan en la promoción del desarrollo sustentable y la cooperación en el ámbito de América Latina. En primer lugar, se describen las características esenciales de los bienes públicos (no rivalidad y no exclusión de beneficios, y tecnología de agregación de la oferta pública) y su influencia en la prognosis de la provisión de bienes públicos regionales. Desde el punto de vista de la acción colectiva...

  6. La preservación de bienes culturales en el Colegio Nacional de Buenos Aires (UBA)

    OpenAIRE

    De Grazia, Amalia; Guidobono, Eugenia; Mayoni, María Gabriela; Wortley, Ana

    2010-01-01

    A partir del año 2007 se dio lugar en el Colegio Nacional de Buenos Aires, proyectos de Revalorización de Bienes Culturales enfocados en la recuperación de material didáctico. La misión de un Plan Integral de Preservación incluye los trabajos de documentación, conservación preventiva y restauración de los bienes culturales, así como la difusión de criterios utilizados y toda aquella información necesaria para el entendimiento de los procesos realizados. Uno de los objetivos fundamentales fue ...

  7. FacturaBien : Sistema de gestión de facturación y contabilidad

    OpenAIRE

    García Núñez, Marcos

    2015-01-01

    El presente documento describe en detalle el proyecto de desarrollo de una aplicación web de gestión, llamada 'FacturaBien'. Esta aplicación permite realizar todas las tareas asociadas a la gestión administrativa de la actividad empresarial de una manera eficiente y cómoda, automatizando un gran número de tareas. Aquest document descriu en detall el projecte de desenvolupament d'una aplicació web de gestió, anomenada 'FacturaBien'. Aquesta aplicació permet realitzar totes les tasques assoc...

  8. bien reconocida

    Directory of Open Access Journals (Sweden)

    N. Prat

    2015-01-01

    Full Text Available En el año 2014 se conmemora el décimo aniversario de la muerte del Profesor Ramón Margalef. En este artículo se hace un repaso a las publicaciones realizadas por el Dr. Margalef, que llegan a un total de 563 trabajos. La temática dominante de los mismos es la ecología acuática, tanto marina como de agua dulce, y mayormente centrados en los estudios de plancton. Sus trabajos están sobre todo publicados en castellano, en catalán y, en menor medida en inglés, en casi 100 revistas diferentes de todo tipo (desde revistas divulgativas a científicas. Destacan por número los artículos publicados en las revistas “Investigación Pesquera” y “Publicaciones del Instituto de Biología Aplicada”, aunque numéricamente los capítulos de libros y las actas de congresos dominan sus trabajos. De todos estos trabajos, 383 se encuentran citados en la “Web of Science” con un promedio cercano a las 100 citas por año, destacando su trabajo de 1978 sobre las formas de vida del fitoplancton, que sigue siendo muy citado (más de 50 citas por año y con tendencia incluso a crecer en el tiempo. Es destacable el poco conocimiento que se tiene de sus libros (con excepción del primero que publicó en inglés titulado “Perspectives in Ecological Theory”, de 1968. A pesar del gran reconocimiento internacional que tuvo Margalef en vida, hoy en día parece que su obra es en gran parte desconocida por los ecólogos del siglo XXI. Su nombre ha desaparecido de los libros de texto de ecología y una de sus grandes aportaciones a la ecología moderna (introducir la teoría de la información en Ecología y el índice de Shannon-Weaver como medida de diversidad no aparece en los manuales de ecología.

  9. VALORACIÓN ECONÓMICA DE BIENES AMBIENTALES POR BENEFICIARIOS CIRCUNDANTES Y NO CIRCUNDANTES

    Directory of Open Access Journals (Sweden)

    Mauricio G Villena

    2013-06-01

    Full Text Available La pregunta básica de investigación detrás de este trabajo es cómo difiere la valoración económica de un bien ambiental considerando beneficiarios circundantes (quienes viven cerca del bien en cuestión y no circundantes (quienes habitando el país donde se encuentra el bien, viven en poblaciones distantes y por tanto disfrutan esporádicamente de los beneficios provistos por el bien ambiental. En particular, en este documento se valora económicamente el Bosque de Algarrobos de la comunidad de Tiataco (Bolivia, realizando un análisis comparativo entre beneficiarios circundantes (familias residentes en la comunidad de Tiataco y beneficiarios no circundantes (familias residentes en la ciudad de Cochabamba, a 35 Km de Tiataco, a través del Método de Valoración Contingente con formato binario. Se estimaron medidas de cambio en el bienestar para ambos grupos, empleando estimaciones paramétricas y no paramétricas. Posteriormente, estas medidas se compararon estadísticamente por medio de la construcción de intervalos de confianza (entre estimaciones paramétricas y no paramétricas de cada población y entre ambas poblaciones. Por último, se identificaron los componentes del valor económico total que los beneficiarios tanto circundantes como no circundantes asignaron al bosque.

  10. Arrendamiento de bienes inmuebles, su tratamiento en el impuesto al valor agregado

    OpenAIRE

    Guarda, Pablo Alberto

    2012-01-01

    El presente trabajo intenta destacar el tratamiento brindado por el Impuesto al Valor Agregado (IVA) al arrendamiento o locación de bienes inmuebles, mostrando en detalle, las distintas modalidades llevadas a cabo en la práctica por locadores y locatarios. Fil: Guarda, Pablo Alberto. Universidad Nacional de Mar del Plata. Facultad de Ciencias Económicas y Sociales; Argentina.

  11. El reconocimiento de las personas con discapacidad. Posibilidad de acceso a los bienes culturales

    OpenAIRE

    Argento Nasser, Ana

    2010-01-01

    Este es un trabajo empírico-conceptual que procura analizar cómo es el real reconocimiento que tienen las personas con discapacidad a institucional. El presente artículo se centra, para delimitar el campo, en el reconocimiento que tienen a nivel cultural, específicamente en el acceso a los bienes culturales.

  12. Mental Health and Well-Being across the Military Spectrum (Bien-etre et sante mentale dans le milieu militaire)

    Science.gov (United States)

    2011-04-01

    Apr 2011 Mental Health and Well-Being across the Military Spectrum ( Bien -être et santé mentale dans le milieu militaire) Research and Technology...Spectrum ( Bien -être et santé mentale dans le milieu militaire) Papers presented at the RTO Human Factors and Medicine Panel (HFM) Symposium held in...research be conducted to demonstrate the usability of these technologies in real world settings. ES - 2 RTO-MP-HFM-205 Bien -être et santé

  13. Atributos característicos de las marcas de bienes de lujo Atributos característicos de las marcas de bienes de lujo

    Directory of Open Access Journals (Sweden)

    Carlos Mario Uribe Saldarriaga

    2006-06-01

    Full Text Available Este artículo presenta una síntesis de la investigación desarrollada por el autor como trabajode grado en el Magíster en Ciencias de la Administración de la Universidad EAFIT. La investigación se centra en la identificación y comprensión de los atributos que caracterizan a las marcas de bienes reconocidas como de lujo, mediante la aplicación de la metodología de investigación denominada análisis de contenido, a una muestra de conveniencia de sitios web de dichas marcas. La investigación se circunscribe al ámbito de estudio del mercadeo y utiliza sus diferentes conceptos para determinar tanto el marco de referencia como la caracterizaciónde los atributos de las marcas de bienes de lujo.This article is a synthesis of the research study conducted by the author as a requirement for the MSc in Management at EAFIT University. The objective in this research is to identify and understand the attributes that characterize brands, acknowledged as luxury goods. The content analysis was chosen as the research method for studying a convenience sample of luxury brand sites on the Internet.  This research study is developed in the marketing field, and its different concepts were adopted as the reference framework.

  14. Usurpaciones de bienes concejiles en Salamanca durante el Reinado de los Reyes Católicos

    Directory of Open Access Journals (Sweden)

    Clara Isabel LÓPEZ BENITO

    2009-12-01

    Full Text Available La realidad económica-social castellana de la Edad Moderna se caracterizó por ser fundamentalmente agraria. Un porcentaje muy elevado de la población activa del Reino trabajaba en el campo, y de él procedía el grueso de las rentas que sustentaban la vida nacional. En la mayoría de los municipios castellanos, junto a las posesiones particulares y junto a aquellas otras que teóricamente pertenecían al rey, existieron las llamadas "tierras concejiles" (o "comunitarias" como prefieren otros autores. Dentro de ellas había que distinguir los "bienes comunales", libremente aprovechados por los vecinos del término municipal, y los "bienes de propios", que el concejo alquilaba a particulares a cambio de una renta que resolvía diversos gastos de la Administración local.

  15. Le « bien-être animal », pourquoi pas ?

    OpenAIRE

    Priolon, Joël

    2011-01-01

    À moins d’être parfaitement insensible au sort réservé aux animaux sauvages ou domestiques, chacun de nous est intéressé par la question du bien-être animal. Être intéressé, et c’est d’emblée un point essentiel, n’implique pas de sombrer dans la passion. Posons donc ceci : la question du bien-être animal peut parfaitement être abordée de manière sereine, ce que Jocelyne Porcher semble nier dès son premier paragraphe ; mais nous ne nous laisserons pas enfermer dans ce type de stratagème rhétor...

  16. La publicidad de bien público y la educación sexual en Cuba

    OpenAIRE

    Hernández Alfonso, Eduardo Alejandro; Paz Enrique, Luis Ernesto

    2016-01-01

    La prevención es una premisa de la educación en salud cubana. Se plantean como objetivos del estudio identificar las características del diseño gráfico cubano para la prevención de las ITS y diseñar una propuesta de bien público basado en nuevos criterios estéticos. El estudio clasifica como investigación aplicada. Se utilizan métodos en los niveles teóricos y empíricos para la recogida de información. La investigación analiza las campañas de bien público orientadas a la prevención de las inf...

  17. EL PATRIMONIO COMO REPRESENTACIÓN COLECTIVA: LA INTANGIBILIDAD DE LOS BIENES CULTURALES

    Directory of Open Access Journals (Sweden)

    Javier Marcos Ar\\u00E9valo

    2012-01-01

    Full Text Available Enfocado desde la perspectiva de la antropología social, el artículo se estructura en torno a los conceptos de tradición, bienes culturales intangibles y representación de la memoria social. Desde planteamientos críticos el trabajo revisa textos fundamentales y analiza y valora los documentos que sobre patrimonio inmaterial ha hecho público la UNESCO en los últimos quince años.

  18. Santé et biens communs : un regard de juriste.

    Directory of Open Access Journals (Sweden)

    Isabelle Moine-Dupuis

    2010-11-01

    Full Text Available La santé constitue un domaine dans lequel les notions de bien commun ou de bien public mondial sont particulièrement pertinentes. Il faut cependant préciser de quels biens il est question. A titre d’exemple, le droit français comporte des notions susceptibles de qualifier le droit aux soins (comme droit inaliénable, ou le médicament, objet de propriété intellectuelle comme de propriété « traditionnelle ». Un droit international des biens de santé peut de la même manière être fondé sur un droit d’usage de chacun sur la molécule qui est la même dans le médicament générique et celui de marque. Une procédure d’accès équivalent aux produits, brevetés ou non, pourrait être mise en œuvre par principe dès la découverte, afin de parvenir rapidement à des prix équitables.Health is a field particularly suitable for notions as commons or public goods. It is necessary however to know which goods may be concerned. For instance, French lawyers use concepts which can be used in order to qualify right to care (as an inalienable right, or medicine as an object of intellectual property as well as “traditional” one. An international law for health goods could be also based on a right of use for each person on the molecule which is the same in the generic drug or in the patented one. A process of “equivalent access” to licensed or free products could be initiated, from the discovery itself to the use, in order to obtain rapidly fair prices.

  19. Sobre el desarrollo de la teoría de los bienes públicos locales

    Directory of Open Access Journals (Sweden)

    Miltón Samuel Camelo

    2015-12-01

    Full Text Available La teoría de los bienes públicos locales toma forma desde la concepciónde la hipótesis de Tiebout, que es el primer planteamiento que tuvo en cuentala dimensión espacial de los bienes públicos, y constituye un mecanismo para la revelación de las preferencias sobre este tipo de bienes. Este trabajo desarrolla la analogía entre el modelo de Tiebout y el modelo neoclásico como una herramienta de dirección del trabajo y no como fin mismo pues, de lo contrario, puede terminar en una discusión ideológica que no es pertinente. Se examina el desarrollo de la teoría a través de la revisión de tópicos relevantes y aportes que han enriquecido y complementado el modelo de Tiebout; y, finalmente, describe elementos esenciales que debe incorporar la teoría para que tenga un mayor poder explicativo.

  20. Producir conocimiento: una discusión entre la propiedad privada y los bienes comunes

    Directory of Open Access Journals (Sweden)

    Beatriz H. Amador Lesmes

    2014-02-01

    Full Text Available El artículo presenta un análisis sobre el fortalecimiento de los dispositivos globales de control en Colombia representados en los sistemas de información de Colciencias. Este hecho habría llevado a su naturalización en las prácticas de los investigadores condicionando las formas de investigar y producir conocimiento. Se busca señalar que estos dispositivos operan a favor de una racionalidad global hegemónica en la cual los bienes intelectuales se asumen y se tratan como bienes privados y objetos del mercado. Esta se contrasta con algunas prácticas emergentes donde la producción de bienes intelectuales se genera a partir de otras lógicas que comprenden el trabajo en relación con la cooperación y la creatividad, desde lo que Virno y Lazzarato llaman trabajo vivo, en especial a través de los usos de Internet.

  1. From DOT to Dotty

    CERN Document Server

    CERN. Geneva

    2017-01-01

    - Module types are interfaces, which can be abstracted. In this talk Martin will present DOT, a particularly simple calculus that can express systems following these principles. DOT has been developed as the foundation of the next version of Scala. He will also report on dotty, a new Scala compiler that implements the constructs of DOT in its core data structures and that uses the lessons learned to drive Scala’s evolution.

  2. OF THE COMMON GOOD TO THE COMMON GOOD OF HUMANITY. DE LOS BIENES COMUNES AL BIEN COMÚN DE LA HUMANIDAD.

    Directory of Open Access Journals (Sweden)

    François Houtart.

    2014-06-01

    éndum sobre el agua (uno de los bienes comunes en Italia, la Fundación Rosa Luxemburgo tomó la decisión de organizar una Conferencia sobre el concepto del Bien Común de la Humanidad, para promover una reflexión sobre los vínculos entre las dos nociones y de integrar las reivindicaciones y las luchas sociales para un cambio de sociedad, escenario en el que se enmarca éste artículo.

  3. Autorización para la venta de los bienes de propiedad de los menores de edad en sede notarial

    OpenAIRE

    Corrales León, Jaime Augusto

    2016-01-01

    Por disposición de la ley, los bienes del menor deben ser conservados ante la imposibilidad de su titular para decidir sobre los mismos; es así que el artículo 297 del Código Civil establece que “No se podrán enajenar ni hipotecar en caso alguno los bienes raíces del hijo, aún pertenecientes a su peculio profesional, sin autorización del juez, con conocimiento de causa”. Los padres quienes ejercen la patria potestad sobre el hijo menor de edad o aquel que administre los bienes por mandato ...

  4. DERECHO INTERNACIONAL PRIVADO Y CONVENIO UNIDROIT DE 24 DE JUNIO DE 1995 SOBRE BIENES CULTURALES ROBADOS O EXPORTADOS ILEGALMENTE

    OpenAIRE

    Calvo Caravaca, Alfonso Luis; Universidad Carlos III de Madrid.

    2004-01-01

    El presente estudio analiza el convenio sobre los bienes culturales ro- bados o exportados ilícitamente, hecho en Roma el 24 de junio de 1995 y elaborado por UNIDROIT. Dicho convenio traza un sistema jurídi- co para lograr la restitución de tales bienes por iniciativa de las partes interesadas o de los estados, según los casos, construyendo una nueva “cultura legal” sobre el tratamiento jurídico de los bienes culturales en los circuitos internacionales del artículo El alcance-espacial del con...

  5. Food as a source of dioxin exposure in the residents of Bien Hoa City, Vietnam.

    Science.gov (United States)

    Schecter, Arnold; Quynh, Hoang Trong; Pavuk, Marian; Päpke, Olaf; Malisch, Rainer; Constable, John D

    2003-08-01

    Recently, elevated dioxin levels, over 5 parts per trillion (ppt) 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), from Agent Orange was reported in 95% of 43 selected residents of Bien Hoa City, a city in southern Vietnam near a former air base used for Agent Orange-spraying missions. Agent Orange herbicide, contaminated with TCDD, was sprayed in Vietnam between 1962 and 1971 primarily for use as a defoliant. Typical blood TCCD levels are 2 ppt in Vietnamese, but levels are as high as 413 ppt in Bien Hoa City. Elevated TCDD was found in children born many years after Agent Orange spraying ended and in immigrants from non-Agent Orange-sprayed parts of Vietnam, which documented new exposures. Extremely elevated soil TCDD samples, over 1 million ppt, and elevated TCDD in sediment were found in some nearby areas such as Bien Hung Lake. The primary route of intake of almost all dioxins in humans is food. However, in our prior studies in Bien Hoa, food was unavailable for dioxin analysis so the route of intake was not confirmed. In the 1970s, while Agent Orange was still being sprayed, elevated human milk TCDD levels as high as 1850 were detected in milk from Vietnamese people living in Agent Orange-sprayed areas where consumption of fish was high. Furthermore, also in the 1970s, elevated TCDD levels (up to 810 ppt) were found in fish and shrimp from the same area as the milk donors. In the 1980s, we found elevated TCDD and also other organohalogen levels in human tissue, pork, fish, a turtle, and a snake in Southern Vietnam. For these reasons, we recently collected food from Bien Hoa and analyzed it for dioxins, polychlorinated biphenyls (PCBs), DDT and its metabolites, and other organochlorines. We found marked elevation of TCDD, the dioxin characteristic of Agent Orange, in some of the food products, including ducks with 276 ppt and 331 ppt wet weight, chickens from 0.031-15 ppt wet weight, fish from 0.063-65 ppt wet weight, and a toad with 56 ppt wet weight. Usual TCDD

  6. Los Bienes Destinados al Uso General: Tratamiento Contable en Diferentes Administraciones Locales Europeas

    Directory of Open Access Journals (Sweden)

    María Teresa Balaguer Coll

    2001-06-01

    Full Text Available Como respuesta a la necesidad de una mayor información para la gestión, los sistemas contables públicos han sido sometidos a un proceso general de reforma, especialmente en la administración local. Estas reformas afectan, entre otros, al tratamiento contable de los activos fijos. Dada la especial naturaleza que poseen algunos de estos activos, como es el caso de los bienes destinados a uso general, este artículo tiene por objeto analizar la problemática contable que tales bienes originan, mostrando diferentes posturas académicas y las prácticas contables de las entidades locales en diferentes países europeos. En general, se aprecia una clara tendencia a la presentación de mayor información sobre el activo fijo en los estados financieros, siendo el criterio de valoración más utilizado el coste histórico. Palabras clave: bienes de uso general, contabilidad pública, entidades locales europeas. ABSTRACT In response to the need for better management information, pubic sector accounting systems have been subjected to a general reform process, especially in local government. These reforms cover, among other things, accounting for capital assets. Given the special nature of some of these assets, such as community assets, this article aims to analyse the problematic roots of accounting, examining different academic positions as well as the accounting rules and practices of local authorities in different European countries. In general, there appears to be a clear tendency to present more information on capital assets in financial statements, with historic cost being the most utilised valuation criteria.

  7. Quantum Dots: Theory

    Energy Technology Data Exchange (ETDEWEB)

    Vukmirovic, Nenad; Wang, Lin-Wang

    2009-11-10

    This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

  8. El reconocimiento de los bienes de dominio público: El caso de los municipios portugueses

    Directory of Open Access Journals (Sweden)

    Susana Catarino Rua

    2016-02-01

    Full Text Available Objeto: Este trabajo tiene por objetivos analizar el mencionado en el POCAL (1999, en las NICSP del IPSASB y en diversas opiniones doctrinales con respecto al reconocimiento de los bienes de dominio público (BDP, así como verificar si existen problemas inherentes al reconocimiento de los BDP en Portugal, superables con la adopción de las NICSP. Diseño/metodología/Enfoque: Para este estudio, fue efectuada una revisión de literatura, de la posición del POCAL (1999, de las NICSP del IPSASB, y de la perspectiva doctrinal, con respecto al reconocimiento de los bienes de dominio público. Además, se realizó un estudio de la evolución de los valores de los bienes de dominio público, de los años 2006 a 2013, del total de los 308 municipios portugueses, para concluir acerca de la existencia de dificultades en el reconocimiento de estos activos y de la necesidad de adoptar los normativos internacionales. Aportaciones y Resultados: En algunos municipios portugueses, el proceso de inventario aún no está concluido, existiendo dificultades con respecto al reconocimiento de los BDP. Dichas dificultades resultan de que el POCAL (1999 no presenta los requisitos para el reconocimiento de los activos; problema superado en la NICSP nº 17 del IPSASB (2006b, que refiere esos requisitos. Adoptar un nuevo Sistema de Normalización Contable aplicable a la Administración Pública (SNC-AP, basado en las NICSP, puede ser la solución para dichas cuestiones, introduciendo criterios a considerar en el reconocimiento de los activos, que aseguren la comparabilidad de la información y de los valores del patrimonio de los municipios portugueses. Limitaciones: La inexistencia de criterios de reconocimiento a seguir por los municipios trae limitaciones al nivel de la comparabilidad de los valores de los diferentes componentes del activo presentados por los varios municipios. Valor añadido: Este trabajo nos enseña que, en Portugal, aún existen problemas con

  9. La promesa de compraventa de bienes inmuebles y el derecho de propiedad

    OpenAIRE

    Salazar Gaspar, Jimmy Roman

    2015-01-01

    El contrato de promesa de bienes inmuebles en la legislación ecuatoriana, es un instrumento fundamental e indispensable en el ámbito económico jurídico y social de las personas, por lo cual resulta evidente y necesario revisar la normativa y su aplicación en el derecho ecuatoriano. En los juzgados y Salas de administración de justicia existe un número alarmante de demandas por incumplimiento o ineficacia de la promesa de compraventa, que obedece a factores propios de los contratantes y a l...

  10. Priorización Ejidal De Criterios Sobre Bienes Públicos: El Caso De Caminos Rurales

    OpenAIRE

    Morales Flores, Francisco Javier; Martín Fernández, Susana; Cadena Iñiguez, Jorge

    2011-01-01

    En este artículo se fijó como objetivo definir las preferencias de la población sobre el mantenimiento de los caminos rurales como vías de flujo de bienes y servicios que usan cotidianamente, para ello se presenta un modelo de participación de la sociedad rural donde se integra la opinión de los beneficiarios en el mantenimiento de los caminos rurales basado en un proceso de análisis jerárquico que valora la importancia de criterios económicos, sociales y ambientales

  11. Die biene und ihre produkte in der kunst und im alltagsleben (Fruhchristliche und byzantinische Zeit

    Directory of Open Access Journals (Sweden)

    Liveri Angeliki

    2010-01-01

    Full Text Available Die vorliegende Arbeit ist in zwei Teile geteilt: den kunst- und kulturhistorischen Teil. Im ersten Teil werden Darstellungen uber Bienen Bienenzucht, Honig und Wachs seit der fruhchristlichen bis zur spatbyzantinischen Zeit vorgefuhrt. Daher ist es als Beitrag in der "Ikonographie" der Biene wahrend dieser Zeit zu verstehen. Im kulturhistorischen Teil werden Informationen uber die Bienenzucht, den Handel mit Honig und Wachs sowie ihre vielfaltige Anwendung von der byzantinischen Gesellschaft an Hand der primaren Quellen, des Standes der Forschung und der archaologischen Funden erwahnt. Damit ist erwunscht ein moglichst gutes Bild der byzantinischen Bienenzucht wieder zu geben und die Nutzung der Bienenprodukte in Byzanz anschaulich zu machen.

  12. Quantum Dot Solar Cells

    Science.gov (United States)

    Raffaelle, Ryne P.; Castro, Stephanie L.; Hepp, Aloysius; Bailey, Sheila G.

    2002-01-01

    We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

  13. Memoria sobre la Red de Estudio y Enseñanza Interdisciplinar del Gobierno del Bien Común

    OpenAIRE

    2015-01-01

    El presente trabajo en red docente ha servido para cuestionar y proponer la reformulación de la enseñanza y la investigación universitaria a partir del “gobierno del bien común”. Desde la Red se ha pretendido reformular el concepto de “bien público” como “bien común” para recalcar el uso común de dichos bienes y la necesidad de su conservación en buen estado para asegurar dicho uso, y evitar las peligrosas “privatizaciones encubiertas”. De ahí que nuestra Red a través de sus distintas discipl...

  14. Diálogos entre feminismos y Buen Vivir/Vivir Bien : distintas perspectivas, múltiples puntos de encuentro

    OpenAIRE

    2013-01-01

    Este artículo surge del diálogo entre distintos saberes y conocimientos, con el objetivo de identificar principalmente las convergencias entre el Buen Vivir/Vivir Bien y los feminismos latinoamericanos. Iniciamos este trabajo considerando las ideas centrales del enfoque del Buen Vivir/Vivir Bien y sus mecanismos de traducción concreta en las reformas constitucionales de Bolivia y Ecuador. Luego, nos detenemos en las confluencias –aunque identificando al...

  15. Vite et bien 1 A1/A2 : méthode rapide pour adultes

    CERN Document Server

    Miquel, Claire

    2009-01-01

    Vite et bien s'adresse à des adultes pressés et impatients de communiquer avec succès en français ! Le vocabulaire est simple et usuel et les thèmes, variés, pour faire face, efficacement, à toutes les situations de la vie quotidienne et professionnelle. Livre + CD audio et corrigés inclus. La méthode rapide Vite et bien 1 permet à la fois d'apprendre le français et de découvrir la réalité de la vie en France, les différences culturelles, le langage de la vie quotidienne, le tout en un temps record. En effet, le premier volume couvre, en vingt unités, les niveaux A1 et A2 du Cadre Européen de référence (CECR). Ainsi, en 100 à 120 heures de cours selon les publics, il sera possible d'acquérir une bonne base de grammaire et de vocabulaire, claire, simple, fonctionnelle, et de se sentir à l'aise dans la communication orale et écrite. L'ouvrage s'adresse aux vrais et et aux faux débutants, constituant donc un outil d'apprentissage et/ou de rafraîchissement des connaissances. Chacune des v...

  16. Restauración del Capital Natural: sin reservas no hay bienes ni servicios

    Directory of Open Access Journals (Sweden)

    J. Aronson

    2007-01-01

    Full Text Available Una de las ideas más innovadoras y atractivas que se están acuñando en la actualidad está relacionada con la necesidad que tiene la humanidad de preservar y manejar los recursos naturales o capital natural - remanente e invertir en la restauración del capital natural (RCN degradado para reincorporarlo a la cadena de bienes y servicios que la sociedad requiere. En este artículo, presentamos definiciones y conceptos básicos, para mostrar como la RCN es un enfoque más amplio en relación al propuesto en la restauración ecológica de ecosistemas naturales. Damos a conocer estudios de caso, como ejemplos del enfoque de la RCN, y su impacto sobre el suministro de bienes y servicios en Argentina, Colombia, México y Chile. Terminamos con una breve discusión y algunas recomendaciones para la investigación y el desarrollo de la RCN a nivel local, regional y global.

  17. El Régimen Fiscal de los bienes de la Iglesia durante el siglo IV

    OpenAIRE

    Santos Yanguas, Narciso

    2011-01-01

    El patrimonio de la Iglesia, aunque remonta en sus orígenes a las comunidades cristianas de los 3 primeros siglos, no tendría un reconocimiento oficial hasta la época de Constantino. A continuación lo consolidaría el emperador Constancio II mediante la aplicación de exenciones fiscales. Dicho patrimonio se incrementaría a través de la apropiación de los templos paganos y de sus bienes, a pesar de la fase de regresión que supone la época de Juliano (361-363). A lo largo del siglo IV el Códi...

  18. The global warming, public goods and carbon market; Calentamiento global, bienes publicos y mercado de carbono

    Energy Technology Data Exchange (ETDEWEB)

    Quadri de la Torre, Gabriel [EcoSecurities (Mexico)

    2007-07-15

    The global warming is an issue of the public goods, and demands an outstanding multilateral action, which must to ensure both efficiency and unchanging transition towards an economy of low intensity of carbon. The new system, which is going to replace the Kyoto Protocol, will have compromises for the developing countries and deep implication in the relative competitivity of the nations and companies. [Spanish] El calentamiento global es un problema de bienes publicos que exige una extraordinaria accion multilateral. Esta debe asegurar eficiencia y una transicion fluida hacia una economia de baja intensidad de carbono. El nuevo sistema que sucedera al Protocolo de Kyoto significara compromisos para los paises en vias de desarrollo, y tendra profundas implicaciones en la competitividad relativa de naciones y empresas.

  19. Evolución y factores del consumo de bienes duraderos en tiempos de crisis prolongadas

    Directory of Open Access Journals (Sweden)

    Víctor Omar Dabbagh Rollán

    2015-01-01

    Full Text Available En las llamadas sociedades de consumo, como es el caso de la española, el elemento sustentador de la misma es el propio consumo. Es por ello que se vuelve imprescindible en situaciones de crisis económica como la actual analizar cómo evoluciona el mismo y determinar qué factores intervienen en él con el fin de prever futuros comportamientos e, incluso, tomar medidas para incentivar aquellos que se considere más oportuno. En este estudio, a partir del estudio de la encuesta del Indicador de Confianza del Consumidor del CIS, se pretende analizar estos aspectos en el consumo de bienes duraderos que se realiza en España en los dos últimos años.

  20. Public health assessment of dioxin-contaminated fish at former US airbase, Bien Hoa, Vietnam.

    Science.gov (United States)

    Durant, James T; Boivin, Thomas G; Pohl, Hana R; Sinks, Thomas H

    2015-01-01

    Ponds at the former US airbase at Ben Hoa, Vietnam are contaminated with Agent Orange. The ponds had been used for aquaculture, and in all likelihood, fish from those ponds have been sold to the public. We assessed human exposure to 2,3,7,8-tetrachloro-dibenzo-dioxin (2,3,7,8-TCDD) in fish samples from the ponds. For on-base tilapia, muscle concentrations 2,3,7,8-TCDD ranged from 1.4 to 32.7 pg/g. Fat concentrations ranged from 73.3 to 3990 pg/g. Estimated human exposure doses exceed international guidelines and exceed 2,3,7,8-TCDD's lowest adverse effect levels. The Bien Hoa fishponds are a completed human pathway for TCDD exposure.

  1. Bienestar subjetivo, renta y bienes relacionales. Los determinantes de la felicidad en España

    Directory of Open Access Journals (Sweden)

    Iglesias Vázquez, Emma

    2013-12-01

    Full Text Available In the present paper we analyze the determinants of happiness proxying by subjective welfare. The main objective is twofold: on the one hand, to put to the test the Easterlin’s paradox (the lack of a direct relationship between income and subjective wellbeing at aggregate level and, on the other hand, to weight influence of relational goods in determining happiness. The analytical framework adopts the perspective of happiness economics and the empirical evidence is derived from the estimation of a microeconometric function of happiness applying a Logit model both when using cross sectional and panel data. The results show that in Spanish society income plays a secondary and subjective role, while other variables that are associated directly or indirectly to relational goods are revealed to be very important.En el presente trabajo se analizan los determinantes de la felicidad, entendida esta como satisfacción subjetiva revelada. El principal objetivo tiene un doble componente: por un lado, se trata de contrastar la paradoja de Easterlin para la sociedad española (ausencia de un vínculo directo entre el incremento de la renta per capita y la evolución del bienestar subjetivo revelado a nivel agregado y, por otro, evaluar el papel que desempeñan los bienes relacionales como determinantes de la felicidad. El marco analítico adoptado se encuadra dentro de la denominada happiness economics y la evidencia empírica se deriva de la estimación de una función microeconométrica de la felicidad aplicando un modelo Logit tanto en cortes temporales como en datos de panel. Los resultados obtenidos permiten concluir que en España el ingreso desempeña un papel secundario y subjetivo, mientras que se revelan como importantes las variables asociadas directa o indirectamente a los bienes relacionales.

  2. Codicia y bien público: los ministros de la Audiencia en la Lima seiscentista

    Directory of Open Access Journals (Sweden)

    de la Puente Brunke, José

    2006-04-01

    Full Text Available The Administration agent was a complex figure in Colonial Peru. This article aims to discuss that complexity, focusing its analysis on the Ministers of Lima’s Audiencia during the Seventeenth century. The concepts of greed (codicia and public good (bien público will be considered in that context, posing some ideas concerning the peculiar way of «selling» judicial posts, known as beneficio. The activities of some of the Audiencia’s Ministers in Lima will be discussed, trying to offer more references on their role in the viceregal society, as well as on their contemporaries’ perception regarding them.

    El presente artículo pretende ofrecer una visión de la complejidad de la figura del agente de la administración pública en el Perú virreinal, centrando su análisis en los ministros de la Audiencia de Lima en el siglo XVII. Como punto de partida, se presentan testimonios a través de los cuales se percibe la tensión entre la «codicia» y el «bien público», y en ese contexto se plantean algunas reflexiones sobre el beneficio de oficios de justicia. Luego se analizan las actividades de algunos de esos ministros en la Lima de entonces, y se busca ofrecer mayores referencias con respecto a su papel en la sociedad virreinal, y en cuanto a la visión que sobre ellos tenían sus contemporáneos.

  3. Graphene quantum dots

    CERN Document Server

    Güçlü, Alev Devrim; Korkusinski, Marek; Hawrylak, Pawel

    2014-01-01

    This book reflects the current status of theoretical and experimental research of graphene based nanostructures, in particular quantum dots, at a level accessible to young researchers, graduate students, experimentalists and theorists. It presents the current state of research of graphene quantum dots, a single or few monolayer thick islands of graphene. It introduces the reader to the electronic and optical properties of graphite, intercalated graphite and graphene, including Dirac fermions, Berry's phase associated with sublattices and valley degeneracy, covers single particle properties of

  4. La elasticidad precio del café mexicano: un modelo para una canasta de bienes, 1976-2000

    OpenAIRE

    2004-01-01

    Plantea el problema de la estimación de las elasticidades precio de la demanda marshalliana, para cualquier bien a partir de canastas de bienes interdependientes y se hace una aplicación al caso del café mexicano, en el periodo 1976-2000. Desde la formulación del concepto de elasticidad por Alfred Marshall en 1886 hasta la actualidad, se ha dado un notable desarrollo en los métodos de estimación. En este artículo se utilizó el Modelo de Demanda Casi Ideal (Almost Ideal Demand System o AIDS) q...

  5. Valuación de Bienes de Uso en el Marco de las Nuevas Normas Contables Profesionales

    OpenAIRE

    2005-01-01

    Respecto a la valuación de los Bienes de Uso el abandono de los valores corrientes, reemplazado por valores históricos, sacrifica los requisitos de aproximación a la realidad, verificabilidad y confiabilidad de la información. Al mismo tiempo, se contradice con Normas Internacionales de Contabilidad (IAS) hacia las que supuestamente buscaba armonizar, ya que éstas (IAS 16) admiten revalorizaciones y desvalorizaciones, con énfasis en mostrar, en todo momento, el fair value de los Bienes de Uso...

  6. Variables del capítulo IV en ISR para la enajenación de bienes inmuebles

    OpenAIRE

    Ochoa León, Jorge

    2011-01-01

    Nuestro trabajo pretende orientar e identificar cuales son las obligaciones y responsabilidades del contribuyente para calcular los impuestos que se causen, tanto en sus pagos provisionales como en la declaración anual, conforme a la ley del impuesto sobre la renta y las diversas disposiciones reglamentarias, que son aplicables en la enajenación de bienes inmuebles. En el cálculo del impuesto por la enajenación de bienes inmuebles, nos damos cuenta de que la responsabilidad no es solo del con...

  7. De las cenizas a la Red: el Periodismo como bien común

    Directory of Open Access Journals (Sweden)

    José Carlos Sendín Gutiérrez

    2014-11-01

    Full Text Available Sampedro nos ofrece y comparte –porque el libro se puede leer en partes también en la red– no sólo y fundamentalmente un alegato a favor del periodismo, sino además, una defensa de un nuevo poder ciudadano y de una nueva democracia. Desde las primeras líneas el lector se siente sacudido por el alto voltaje de los datos, los personajes y el análisis perspicaz de la transformación social que parece apuntarse, pero que hasta ahora nadie había sabido traducir en palabras. Palabras que a veces parecen querer levantar por las solapas al que lee, como diciendo, “entérate, está pasando ahora y es importante que lo descubras”, mientras desarrolla ideas a las que vuelve y recalca, pasados los capítulos, en un ejercicio circular que pretende dejar clara –y lo consigue– la tesis central: ya existe una nueva forma de periodismo entendido como bien común (sí, al igual que el agua o el aire que respiramos, libre, de código abierto y mancomunado. Aire nuevo para una sociedad desencantada, para un periodismo en busca de modelos y para unas aulas donde se forman los futuros profesionales en una universidad maltratada, pero quizá por ello, también sumida en la conformidad de un saber rutinario.

  8. Sociedad conyugal. partición: adjudicación de bien propio

    Directory of Open Access Journals (Sweden)

    Dora Bagdassarian

    2015-10-01

    Full Text Available El objeto del presente apunta al estudio, de la viabilidad y fundamentalmente a la naturaleza jurídica de la adjudicación de un bien propio de uno de los cónyuges, al otro, en la partición, en la hipótesis de la disolución de la sociedad conyugal. No obstante, para abordar el tema concreto consideramos necesario. algunas breves referendas a determinados aspectos de la sociedad conyugal y concretamente a la partición en general.Contenido: Introducción. Concepto de negocio jurídico. Partición. Ubicación de la partición en la clasificación de los negocios jurídicos. Efecto declarativo retroactivo de la partición. Aplicación del art.1151 C.C. a la partición de la sociedad conyugal. Presupuestos de la partición y de su efecto declarativo. Aplicación de lo expuesto al caso concreto

  9. Bien faire un cours, un exposé, une conférence

    CERN Document Server

    Brown, George

    1981-01-01

    Le livre de Georges Brown est un livre important pour deux raisons : - Parce qu'il propose à tous les formateurs et enseignants une approche méthodologique de la transmission orale des connaissances. En effet, il ne suffit pas de bien connaître son sujet pour le faire comprendre à son auditoire. Ce livre est conçu pour mener le lecteur pas à pas dans la découverte de son propre style d'explication, de ses points faibles et de ses points forts. - Parce qu'il permet au lecteur, grâce à la pratique des 45 exercices contenus dans l'ouvrage, de faire alterner la réflexion et la performance individuelle avec l'échange d'expériences et l'auto-évaluation des méthodes d'enseignement oral. Ce livre, qui possède toutes les qualités du pragmatisme anglo-saxon, met au service de la formation un outil essentiellement pratique. Il s'adresse donc à tous ceux qui donnent des cours, font des séminaires,ou ont à exposer leurs idées devant un auditoire. EXPLIQUER, C'EST D'ABORD SAVOIR COMMUNIQUER.

  10. Evolución reciente de la industria argentina de bienes de capital

    Directory of Open Access Journals (Sweden)

    RICARDO ORTIZ

    2013-05-01

    Full Text Available Este artículo busca identificar los principales rasgos del desempeño de la industria argentina de bienes de capital desde una perspectiva de mediano plazo. En particular, se hace eje en los aspectos distintivos de la trayectoria sectorial verificada durante la década de los noventa, cuando estuvo en plena vigencia el modelo neoliberal y se atacó al sector de muy diversas maneras y en la fase de la posconvertibilidad iniciada formalmente a comienzos del año 2002 y que dio lugar a un importante ciclo expansivo de la actividad económica con un rol destacado de la industria manufacturera. Abstract This paper aims to identify the main features of the performance of the argentine industry of capital goods from a medium-term perspective. In particular, the focus is placed upon the distinctive aspects of the sectorial trend verified during the nineties, when the neoliberal model was at its highest validity and the sector was attacked in many different ways and at the stage of “posconvertibilidad” formally initiated in early 2002, which led to a significant expansive cycle of the economic activity with an important role of the manufacturing sector.

  11. Vertical distribution of dioxins in soil of Bien Hoa airbase, Vietnam.

    Science.gov (United States)

    Huyen, Dang Thuong; Igarashi, Toshifumi; Shiraiwa, Takuya

    2015-01-01

    Bien Hoa airbase is a known dioxin-contaminated hotspot in Vietnam. The contamination occurred during the Vietnam War at the site where dioxins were transported, stored, sprayed, and spilled in the area. Dioxins, which are cancer inducing substances, may transfer from the soil to food crops and finally to human beings living around the area. Many surveys of dioxins in soil, water, organisms, and human have been carried out in this study area since 2002. In this paper vertical distribution of dioxins in undisturbed soil cores were examined. Twelve soil samples from three drilled cores were collected to analyze dioxin levels according to the standard Japanese analytical method. The results showed that the toxicity equivalency quantity (TEQ) in one soil sample at a depth of 2.6 m reached 3,300 pg-TEQ/g-dw. High TEQs were also observed in the clay layer. This anomaly of dioxin concentrations could be attributed to the affinity of dioxins for the clay layer. The isomer patterns in the soils were different from those in the soil of Hokkaido in that 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) was the most dominant in the soil sample. This indicates that the dioxins originate from a defoliant Agent Orange disposed at the site after the Vietnam War.

  12. Hexagonal graphene quantum dots

    KAUST Repository

    Ghosh, S.

    2016-12-05

    We study hexagonal graphene quantum dots, using density functional theory, to obtain a quantitative description of the electronic properties and their size dependence, considering disk and ring geometries with both armchair and zigzag edges. We show that the electronic properties of quantum dots with armchair edges are more sensitive to structural details than those with zigzag edges. As functions of the inner and outer radii, we find in the case of armchair edges that the size of the band gap follows distinct branches, while in the case of zigzag edges it changes monotonically. This behaviour is further analyzed by studying the ground state wave function and explained in terms of its localisation.

  13. Quantum dot solar cells

    CERN Document Server

    Wu, Jiang

    2013-01-01

    The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou

  14. Consumo de bienes culturales: reflexiones sobre un concepto y tres categorías para su análisis

    Directory of Open Access Journals (Sweden)

    Luz María Ortega Villa

    2009-01-01

    Full Text Available En este artículo se revisa la elaboración de lo que aquí se denomina consumo de bienes culturales como concepto alternativo al de consumo cultural. El artículo propone a la vez tres categorías de análisis para el objeto de estudio que el primer concepto define.

  15. Fuzzy Dot Structure of BG-algebras

    Directory of Open Access Journals (Sweden)

    Tapan Senapati

    2014-09-01

    Full Text Available In this paper, the notions of fuzzy dot subalgebras is introduced together with fuzzy normal dot subalgebras and fuzzy dot ideals of BG-algebras. The homomorphic image and inverse image are investigated in fuzzy dot subalgebras and fuzzy dot ideals of BG-algebras. Also, the notion of fuzzy relations on the family of fuzzy dot subalgebras and fuzzy dot ideals of BG-algebras are introduced with some related properties.

  16. Electron correlations in quantum dots

    CERN Document Server

    Tipton, D L J

    2001-01-01

    Quantum dot structures confine electrons in a small region of space. Some properties of semiconductor quantum dots, such as the discrete energy levels and shell filling effects visible in addition spectra, have analogies to those of atoms and indeed dots are sometimes referred to as 'artificial atoms'. However, atoms and dots show some fundamental differences due to electron correlations. For real atoms, the kinetic energy of electrons dominates over their mutual Coulomb repulsion energy and for this reason the independent electron approximation works well. For quantum dots the confining potential may be shallower than that of real atoms leading to lower electron densities and a dominance of mutual Coulomb repulsion over kinetic energy. In this strongly correlated regime the independent electron picture leads to qualitatively incorrect results. This thesis concentrates on few-electron quantum dots in the strongly correlated regime both for quasi-one-dimensional and two-dimensional dots in a square confining p...

  17. Marketing Ético como Fundamento del Bien Común en Organizaciones Humanas

    Directory of Open Access Journals (Sweden)

    Alejandro Fernández Baptista

    2014-01-01

    Full Text Available Los hombres poseen necesidades que deben ser satisfechas con el objeto de lograr una vida cónsona con los principios básicos de dignificación de la persona humana, alimento, vestido, medicamentos, comunicación, entretenimiento, transporte, entre otras, son algunas de las necesidades básicas que los seres humanos día tras día se esfuerzan por cubrir mediante el trabajo digno, utilizando para ello las potencialidades propias de cada quien. Las organizaciones modernas por medio del marketing como proceso administrativo, pretende lograr la satisfacción de tales necesidades por medio de la identificación oportuna de dichos requerimientos, elaborando productos y servicios que los satisfagan al crear una propuesta de valor superior a tales expectativas. Sin embargo, tal propuesta debería estar inmersa dentro de parámetros éticos y morales, las cuales garanticen la correcta utilización de cada uno de los elementos de la mezcla de mercadotecnia, producto, precio, promoción y la distribución. De esta manera los gerentes de marketing al momento de tomar decisiones éticas sobre estos tópicos, permitirían en desarrollo de organizaciones humanas promotoras del bien común dentro del contexto donde se desenvuelvanPalabras Clave: Marketing ético; Bien Común; Organizaciones Humanas. Marketing Ethical as the Foundation of the Common Wealth on Human OrganizationsAbstractThe people have needs that must be met for a life in keeping with the basic principles of dignification of the human person, food, clothing, medicines, communication, entertainment, transportation, among others, are some of the basic needs of human beings every day strive to cover using decent, using work of their own potential each person. Modern organizations marketing as administrative process aims at achieving the satisfaction of those needs in the timely identification of those requirements, developing products and services satisfying them to create a proposal for a value

  18. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small si

  19. El derecho a comer: Los alimentos como bien público global

    Directory of Open Access Journals (Sweden)

    Ausín, Txetxu

    2010-10-01

    Full Text Available Eating and drinking are essential needs of every human being in every culture and society, and its lack leads to obvious and objective damage. Therefore, food and water becomes moral in terms of universal human right to eat and drink, one of those rights that give and preserve life. However, humanity lives in a grave and intolerable situation of famine, due to structural factors such as international trade and financial policies, production of biofuels, and the abandonment of consumption agriculture, among others. This scenario requires a deep rethinking of public policy on food and drinking water, departing from its conceptualization as public goods, and not as mere commodities.

    Comer y beber son necesidades esenciales de todo ser humano, en toda cultura y sociedad, y su carencia produce, evidentemente, daños graves y objetivos. Por ello, el alimento y el agua potable devienen en exigencias morales universales en términos del derecho humano a comer y a beber, uno de esos derechos que dan y preservan la vida. Sin embargo, la humanidad vive sumida en una gravísima e intolerable situación de hambruna a la que contribuyen algunos factores estructurales como las políticas comerciales y financieras internacionales, la producción de biocombustibles y el abandono de la agricultura de consumo, entre otros. Este panorama obliga a una profunda reformulación de las políticas públicas sobre el alimento y el agua potable, que partan de su conceptualización como bienes públicos y no meras mercancías.

  20. Bienes rústicos de aprovechamiento público en la Valencia moderna

    Directory of Open Access Journals (Sweden)

    David BERNABÉ GIL

    2009-12-01

    Full Text Available RESUMEN: Analiza el presente trabajo diversos aspectos relacionados con los derechos de aprovechamiento público que confluían en los espacios rústicos no cultivados del antiguo Reino de Valencia, así como la naturaleza de los problemas que solía suscitar su atribución dominical, dada la frecuente superposición de instancias institucionales con pretensiones de control. A partir de la compleja tipología que la casuística al respecto —aún escasa y mal conocida— permite entrever, queda en evidencia el fuerte arraigo de los elementos de regulación municipal vigentes en el realengo, si bien en franco retroceso ante los tardíos intentos de control por el Real Patrimonio. En los señoríos, sin embargo, son los derechos del titular de la jurisdicción los que consiguen prevalecer, aunque no necesariamente por exclusión de los reconocidos a la comunidad.ABSTRACT: This study analyzes different aspects related to the rights of public usage with regard to uncultivated agricultural spaces in the ancient Kingdom of Valencia, as well as the nature of the problems normally arising from the conferring of their feudal status, due to the frequent superimposing of institutional requests to gain control. With regard to the complex typology that the corresponding casuistry (still scarce and hardly known suggests, we can highlight the fact that the elements of municipal regulation that existed within the state were well-established, although they were clearly in decline in the face of the Royal Trust's late attempts to gain control. However, as regards the estates, the ownership rights of the jurisdiction were the ones that finally prevailed, although not necessarily by excluding the rights of the community.

  1. Colloidal Double Quantum Dots.

    Science.gov (United States)

    Teitelboim, Ayelet; Meir, Noga; Kazes, Miri; Oron, Dan

    2016-05-17

    Pairs of coupled quantum dots with controlled coupling between the two potential wells serve as an extremely rich system, exhibiting a plethora of optical phenomena that do not exist in each of the isolated constituent dots. Over the past decade, coupled quantum systems have been under extensive study in the context of epitaxially grown quantum dots (QDs), but only a handful of examples have been reported with colloidal QDs. This is mostly due to the difficulties in controllably growing nanoparticles that encapsulate within them two dots separated by an energetic barrier via colloidal synthesis methods. Recent advances in colloidal synthesis methods have enabled the first clear demonstrations of colloidal double quantum dots and allowed for the first exploratory studies into their optical properties. Nevertheless, colloidal double QDs can offer an extended level of structural manipulation that allows not only for a broader range of materials to be used as compared with epitaxially grown counterparts but also for more complex control over the coupling mechanisms and coupling strength between two spatially separated quantum dots. The photophysics of these nanostructures is governed by the balance between two coupling mechanisms. The first is via dipole-dipole interactions between the two constituent components, leading to energy transfer between them. The second is associated with overlap of excited carrier wave functions, leading to charge transfer and multicarrier interactions between the two components. The magnitude of the coupling between the two subcomponents is determined by the detailed potential landscape within the nanocrystals (NCs). One of the hallmarks of double QDs is the observation of dual-color emission from a single nanoparticle, which allows for detailed spectroscopy of their properties down to the single particle level. Furthermore, rational design of the two coupled subsystems enables one to tune the emission statistics from single photon

  2. Problemática sobre la disponibilidad de los Bienes Jurídicos Individuales y Responsabilidades Emergentes

    Directory of Open Access Journals (Sweden)

    Ignacio Curbelo Solari

    2013-12-01

    Full Text Available Sobre el concepto de Disponibilidad. Concepto de Bien Jurídico y sus funciones. El Consentimiento. Breve Historia. Bienes Jurídicos Colectivos e Individuales. Naturaleza Jurídica del Consentimiento. Posición de Jescheck, Roxin y Muñoz Conde. Posición de los principales autores nacionales: Prof. Gonzalo Fernández, Miguel Langón, Germán Aller, Pedro Montano. Los requisitos del consentimiento. En la doctrina extranjeraEn la doctrina uruguaya El consentimiento presunto. Requisitos del consentimiento presunto.Relevancia del consentimiento en el Derecho Positivo. Derecho extranjero Derecho Uruguayo. Diversas situaciones. El art. 44 del CP. La Vida. El consentimiento y la responsabilidad de los médicos. Las intervenciones transexuales. La Eutanasia La ley 18.473 de Voluntad anticipada. La auto puesta en peligro.

  3. Análisis de los criterios de intervención en Bienes Eclesiásticos

    Directory of Open Access Journals (Sweden)

    María José González López

    2015-06-01

    Full Text Available En este artículo se analizan los criterios con los que se debe abordar la intervención en bienes culturales de procedencia eclesiástica en nuestro país a partir del análisis de los apartados específicos de la normativa dictada por el Estado Español y por la Santa Sede, así como en la concordada mediante acuerdos y convenios suscritos entre ambos.

  4. Environmental Health Risk Assessment of Dioxin Exposure through Foods in a Dioxin Hot Spot—Bien Hoa City, Vietnam

    OpenAIRE

    Tran Thi Tuyet-Hanh; Le Vu-Anh; Nguyen Ngoc-Bich; Thomas Tenkate

    2010-01-01

    This study used the Australian Environmental Health Risk Assessment Framework to assess the human health risk of dioxin exposure through foods for local residents in two wards of Bien Hoa City, Vietnam. These wards are known hot-spots for dioxin and a range of stakeholders from central government to local levels were involved in this process. Publications on dioxin characteristics and toxicity were reviewed and dioxin concentrations in local soil, mud, foods, milk and blood samples were used ...

  5. Nanocrystal quantum dots

    CERN Document Server

    Klimov, Victor I

    2010-01-01

    ""Soft"" Chemical Synthesis and Manipulation of Semiconductor Nanocrystals, J.A. Hollingsworth and V.I. Klimov Electronic Structure in Semiconductor Nanocrystals: Optical Experiment, D.J. NorrisFine Structure and Polarization Properties of Band-Edge Excitons in Semiconductor Nanocrystals, A.L. EfrosIntraband Spectroscopy and Dynamics of Colloidal Semiconductor Quantum Dots, P. Guyot-Sionnest, M. Shim, and C. WangMultiexciton Phenomena in Semiconductor Nanocrystals, V.I. KlimovOptical Dynamics in Single Semiconductor Quantum Do

  6. Quantum dot nanostructures

    Directory of Open Access Journals (Sweden)

    Mohamed Henini

    2002-06-01

    These sophisticated technologies for the growth of high quality epitaxial layers of compound semiconductor materials on single crystal semiconductor substrates are becoming increasingly important for the development of the semiconductor electronics industry. This article is intended to convey the flavor of the subject by focusing on the technology and applications of self-assembled quantum dots (QDs and to give an introduction to some of the essential characteristics.

  7. Predictors for dioxin accumulation in residents living in Da Nang and Bien Hoa, Vietnam, many years after Agent Orange use.

    Science.gov (United States)

    Pham, Diem T; Nguyen, Hang M; Boivin, Thomas G; Zajacova, Anna; Huzurbazar, Snehalata V; Bergman, Harold L

    2015-01-01

    Agent Orange (AO) was the main defoliant used by the US in Vietnam from 1961 to 1971; AO was contaminated with dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD). Three major dioxin “hot spots” remain from previous AO storage and use at former US bases at Bien Hoa, Da Nang, and Phu Cat, posing potential health risks for Vietnamese living on or near these hot spots. We evaluated potential risk factors contributing to serum TCDD levels in Vietnamese residents at and near contaminated sites in Da Nang and Bien Hoa, Vietnam. We used multiple linear regression to analyze possible associations of blood dioxin concentrations with demographic, socioeconomic, lifestyle, and dietary risk factors for residents living on or near these hot spots. For the Da Nang study, fish farming on the site, living on property flooded from monsoon rains, and age were among the factors showing significant positive associations with serum TCDD concentrations. For the Bien Hoa study, fish farmers working at this site and their immediate family members had significantly higher serum TCDD concentrations. Our results suggest that water-related activities, especially fish-farming, at the hot spots increased the risk of exposure to dioxin.

  8. Inter-dot coupling effects on transport through correlated parallel coupled quantum dots

    Indian Academy of Sciences (India)

    Shyam Chand; G Rajput; K C Sharma; P K Ahluwalia

    2009-05-01

    Transport through symmetric parallel coupled quantum dot system has been studied, using non-equilibrium Green function formalism. The inter-dot tunnelling with on-dot and inter-dot Coulomb repulsion is included. The transmission coefficient and Landaur–Buttiker like current formula are shown in terms of internal states of quantum dots. The effect of inter-dot tunnelling on transport properties has been explored. Results, in intermediate inter-dot coupling regime show signatures of merger of two dots to form a single composite dot and in strong coupling regime the behaviour of the system resembles the two decoupled dots.

  9. Ética de la convivencia en organizaciones del presente: Base fundamental para alcanzar el bien común

    Directory of Open Access Journals (Sweden)

    Cristina Seijo

    2014-01-01

    Full Text Available El propósito de esta investigación es establecer algunas consideraciones teóricas sobre la ética de la convivencia en las organizaciones de presente, de manera que la gerencia en estas organizaciones se perfile hacia la búsqueda del bien común, en este sentido, el estudio se basa en una metodología cualitativa, de tipo descriptiva y diseño no experimental, mediante un análisis documental, ubicada dentro del área de las Ciencias Sociales.En este sentido, el logro del bien común está asociado a alcanzar una vida en convivencia, esto significa lograr acuerdos mínimos a través del diálogo entre los ciudadanos de manera que se pueda establecer el respeto hacia el otro. La base de tales acuerdos será, necesariamente, la búsqueda del bienestar de la sociedad, es decir, el bien común. Esta idea justifica la necesidad de una ética común, la que conlleva al reconocimiento del otro, aceptar el bienestar del otro, aceptación del otro en nuestro sistema, para lograr la convivencia y alcanzar el bienestar o bien común.Palabras Clave: Ética de la convivencia; bien común; acuerdos mínimos. Ethics of the Living together in organizations of future: fundamental Base to reach the common goodAbstractThis research aims at advancing concepts regarding fellowship ethics in contemporary organizations, in order to organize management around common good practices. The achievement of the common good is thus associated to reaching fellowship, this is to achieve minimal consensus through dialog between citizens and strengthen respect to each other. The base of such consensus will be, necessarily, societal welfare, that is to say, the common good.Keywords: Ethics of the living; common good; minimal agreements.

  10. Economía, bienes públicos puros e Internet : revelando el caso del FLOSS (“Free/Libre Open Source Software” o “Software Libre y Software de Código Abierto”)

    OpenAIRE

    Soler Muñoz, Rafael

    2013-01-01

    Desde que Paul Samuelson publicase en 1954 su obra “The pure theory of public expenditure”, diferenciando los bienes económicos entre bienes públicos y bienes privados, ha existido controversia sobre la posibilidad de que los bienes públicos pudiesen encontrarse en estado "puro". En nuestra tesis exponemos, con el ejemplo del FLOSS (Free/Libre Open Source Software), como la existencia de bienes públicos puros tendría lugar cuando bienes digitales son distribuidos a través de redes "peer to pe...

  11. Single quantum dot nanowire photodetectors

    NARCIS (Netherlands)

    Van Kouwen, M.P.; Van Weert, M.H.M.; Reimer, M.E.; Akopian, N.; Perinetti, U.; Algra, R.E.; Bakkers, E.P.A.M.; Kouwenhoven, L.P.; Zwiller, V.

    2010-01-01

    We report InP nanowire photodetectors with a single InAsP quantum dot as light absorbing element. With excitation above the InP band gap, the nanowire photodetectors are efficient (quantum efficiency of 4%). Under resonant excitation of the quantum dot, the photocurrent amplitude depends on the line

  12. Retos para la política ambiental: el debate internacional sobre el comercio de bienes y servicios ambientales

    Directory of Open Access Journals (Sweden)

    Diego Alejandro Martínez Ballesteros

    2006-01-01

    Full Text Available Los lineamientos de la actual política ambiental nacional enfatizan la promoción y el aprovechamiento sostenible de bienes y servicios ambientales. A nivel internacional, el tema se está tratando en la Organización Mundial del Comercio, por el mandato de la Declaración Ministerial de Doha (2001. Así mismo, se encuentra tácitamente en la actual agenda del desarrollo. El debate ha girado alrededor de lograr un acuerdo sobre definiciones y criterios de bienes y servicios ambientales para el comercio. Se ha mantenido una visión restringida sobre estos ítems, que excluye apreciaciones integrales desde la economía ambiental. Los bienes y servicios relacionados con la biodiversidad y los que proporcionan los ecosistemas, que podrían interesar a los países ‘megadiversos’ como Colombia no ocupan el centro del debate. La ausencia y la pasividad en este debate pueden conllevar a la pérdida de beneficios y oportunidades de la utilización sostenible de los recursos naturales, en contravía con la intención de la actual política ambiental. Así mismo, los resultados que se logren en la OMC tendrán repercusiones en otros tratados comerciales bilaterales o regionales que celebre el país y en el nivel de autonomía sobre el control de recursos naturales estratégicos

  13. Retos para la política ambiental: el debate internacional sobre el comercio de bienes y servicios ambientales

    Directory of Open Access Journals (Sweden)

    Diego Alejandro Martínez Ballesteros

    2006-11-01

    Full Text Available Los lineamientos de la actual política ambiental nacional enfatizan la promoción y el aprovechamiento sostenible de bienes y servicios ambientales. A nivel internacional, el tema se está tratando en la Organización Mundial del Comercio, por el mandato de la Declaración Ministerial de Doha (2001. Así mismo, se encuentra tácitamente en la actual agenda del desarrollo. El debate ha girado alrededor de lograr un acuerdo sobre definiciones y criterios de bienes y servicios ambientales para el comercio. Se ha mantenido una visión restringida sobre estos ítems, que excluye apreciaciones integrales desde la economía ambiental. Los bienes y servicios relacionados con la biodiversidad y los que proporcionan los ecosistemas, que podrían interesar a los países ‘megadiversos’ como Colombia no ocupan el centro del debate. La ausencia y la pasividad en este debate pueden conllevar a la pérdida de beneficios y oportunidades de la utilización sostenible de los recursos naturales, en contravía con la intención de la actual política ambiental. Así mismo, los resultados que se logren en la OMC tendrán repercusiones en otros tratados comerciales bilaterales o regionales que celebre el país y en el nivel de autonomía sobre el control de recursos naturales estratégicos.

  14. La Protección Jurídica de los Bienes Culturales en el Derecho Español

    Directory of Open Access Journals (Sweden)

    Luis A. Anguita Villanueva

    2004-01-01

    Full Text Available RESUMEN El presente artículo trata de la protección de los bienes que manifiestan elementos o valores de la cultura española. Se define, primero, el concepto y el contenido normativo de los bienes culturales a la luz del derecho positivo, tanto nacional español como supranacional. Se revisan, luego, los antecedentes históricos de la protección de los bienes culturales en el Derecho español, para luego examinar el marco jurídico actual del patrimonio histórico, tanto desde la perspectiva de la normativa supranacional (UNESCO, el Consejo de Europa, la Unión Europea y el Convenio de UNIDROIT, como de la normativa nacional, expresada en la Constitución, el ordenamiento estatal y los ordenamientos autonómicos. El trabajo pone de relieve que la complejidad de la protección de los bienes culturales deriva, en parte, de la dificultad de definir o delimitar el concepto de cultura en la ciencia del Derecho y, por otro lado, de la división político-competencial que se diseña en España a través de la Constitución de 1978, que ha dado pie a una hipertrofia normativa, común a los países de modelo "federal" de distribución de competencias, que dificulta la aplicación por parte de los operadores jurídicos.ABSTRACT The article examines the status of objects which embody elements or values of the Spanish culture. First, the legal notion of cultural objects is defined, considering national and supranational law. We then review the historical background of the protection of cultural objects in Spanish law, turning next to the current legal framework for the protection of the historical patrimony, both from a supranational normative perspective (UNESCO, the Council of Europe, The European Union, and the UNIDROIT agreement, and the Spanish national law found in the Constitution, the national law, and the law of the autonomous regions. Throughout the article the notion is stressed that the complexity we find in the protection of cultural

  15. Evaluación del aprendizaje de adolescentes del proyecto Bebé Piénsalo Bien (BPB)

    OpenAIRE

    Velandía Pedraza, Ángela Lucía

    2013-01-01

    El presente documento es un estudio mixto con predominio cualitativo, cuyo objetivo es determinar los aspectos fundamentales del aprendizaje significativo presentes para el abordaje de los temas de maternidad y paternidad responsable en los grupos de adolescentes que participaron en el proyecto de Bebé Piénsalo Bien (BPB) en el colegio Técnico Internacional. Como instrumento se aplicó individualmente la misma encuesta que se aplicó a los adolescentes que participaron en el proyecto bebé piéns...

  16. Bienes públicos regionales para la fortificación de alimentos con micronutrientes en Centroamérica

    OpenAIRE

    Isabel Nieves; Nicté Ramírez; Alexa N. Monroy

    2012-01-01

    El proyecto de bienes públicos regionales (BPR) en fortificación masiva de alimentos de alto consumo que el BID co-financió en el 2007 para el conjunto de los siete países de la región, se diseñó bajo la premisa que a través de la cooperación transnacional se pueden potenciar los avances en el control de las deficiencias de micronutrientes prevalentes que, hasta entonces, se abordaban mayormente de manera individual.

  17. Observaciones sobre la opinión pública a partir de "El ciudadano bien informado"

    OpenAIRE

    Juárez, Benjamín

    2008-01-01

    Alfred Schutz se pregunta hasta qué punto tienen y pueden llegar las responsabilidades civiles. Antes de eso se pregunta por las preocupaciones e intereses del ciudadano y la importancia del pensamiento razonable anclado en la individualidad y en contraposición a la opinión desinformada de la masa. En este escrito se busca no tanto ni solamente responder a la inquietud de Schutz, sino darle historia y significado al problema que presenta. Se enuncia lo que se entiende por ciudadano bien infor...

  18. Perspectivas sobre la gobernanza de los bienes y la ciudadanía en la obra de Elinor Ostrom

    OpenAIRE

    Leticia Merino Pérez

    2014-01-01

    Este trabajo reflexiona sobre las principales aportaciones conceptuales y me - todológicas de la obra de Elinor Ostrom, con - siderando el contexto conceptual y político en que emergió y se desarrolló: la polémica con las hegemónicas tesis de Garret Hardin sobre la tragedia de los bienes comunes y la teo - ría de la elección racional. Analiza las ruptu - ras y continuidades de la obra de Ostrom en relación con distintos paradigmas dominantes en las ciencias sociales. Indica también que sus ap...

  19. Aristocracia local y trasvases de bienes en Liébana (siglo XIII. Revisión del problema

    Directory of Open Access Journals (Sweden)

    Rosana Vassallo

    2013-03-01

    Full Text Available El presente trabajo analiza los trasvases de bienes entre aristocracias locales y monasterios. Las donaciones pro anima, realizadas por los sectores destacados de la sociedad, quedaron vinculadas tradicionalmente a las necesidades espirituales de la aristocracia, reduciendo la actuación patrimonial del sector en un sentido unidireccional. El presente estudio pretende reubicar dichos trasvases en un juego más amplio de transacciones mutuas que sólo pueden ser entendidas apelando a las estrategias de reproducción social de los sujetos actuantes

  20. Bienes de titularidad pública: Patrimoniales y de dominio público. Una aproximación al sistema español

    Directory of Open Access Journals (Sweden)

    Luís Hernando Van-Strahlen-Fajardo

    2010-03-01

    Full Text Available Se realiza en este texto una aproximación puntual al régimen jurídico de los bienes de titularidad pública en España. Se comienza por la tradicional distinción entre bienes de dominio público y bienes patrimoniales o privados del Estado, donde se evidencia la ambigua frontera que separa al derecho público y al derecho privado. Luego se describen con mayor detenimiento las formas, las técnicas y los modos jurídicos para la adquisición, la enajenación, la cesión, la transferencia y la protección de los bienes de naturaleza patrimonial; así como una breve observación sobre una especie particular de estos últimos, que conforman el llamado patrimonio empresarial.

  1. Tout va bien ! méthode de français : cahier d'exercices 1

    CERN Document Server

    Augé, H; Marlhens, C; Martin, L

    2005-01-01

    Tout va bien ! est une méthode de français destinée aux grands adolescents et adultes débutants ou faux-débutants. Ses objectifs respectent scrupuleusement les recommandations du Cadre européen commun de référence pour les langues, comme en témoigne le portfolio qui accompagne le livre de l'élève. Tout va bien ! propose : Des supports et des situations de communication authentiques ou proches de l'authentique, permettant à l'élève de se sensibiliser aux différents registres et de découvrir certains aspects de la culture francophone tout autant que la langue. De très nombreuses activités visant l'acquisition des quatre compétences de communication et l'utilisation de stratégies spécifiques. Un travail sur la grammaire et le vocabulaire associés aux situations et au service de la communication faisant une large place à l'observation et à la réflexion. Une invitation régulière à l'évaluation, au travail an autonomie et à l'auto-évaluation.

  2. Tout va bien ! méthode de français : cahier d'exercices 2

    CERN Document Server

    Augé, H; Marlhens, C; Martin, L

    2005-01-01

    Tout va bien ! est une méthode de français destinée aux grands adolescents et adultes débutants ou faux-débutants. Ses objectifs respectent scrupuleusement les recommandations du Cadre européen commun de référence pour les langues, comme en témoigne le portfolio qui accompagne le livre de l'élève. Tout va bien ! propose : Des supports et des situations de communication authentiques ou proches de l'authentique, permettant à l'élève de se sensibiliser aux différents registres et de découvrir certains aspects de la culture francophone tout autant que la langue. De très nombreuses activités visant l'acquisition des quatre compétences de communication et l'utilisation de stratégies spécifiques. Un travail sur la grammaire et le vocabulaire associés aux situations et au service de la communication faisant une large place à l'observation et à la réflexion. Une invitation régulière à l'évaluation, au travail an autonomie et à l'auto-évaluation.

  3. Vivir bien, buen vivir: caminar con los dos pies (Living well, good living: walking with both feet

    Directory of Open Access Journals (Sweden)

    José María Tortosa

    2011-07-01

    Full Text Available ResumenEl texto recoge, a modo de introducción, una reflexión sobre el concepto del Buen Vivir/Vivir bien, los motivos de su relativo éxito en el contexto latinoamericano y su importancia tanto en el terreno simbólico como en su capacidad de revelar los errores del desarrollo en el sistema mundial. El Buen Vivir/Vivir Bien es un concepto en construcción, y de ahí la importancia de avanzar en la identificación de variables e indicadores que permitan su medición.AbstractAs an introduction, this text is a consideration on the concept of Good Living / Living Well, the reasons for its relative success in the Latin American context and its importance both as a symbolic field and its ability to reveal errors in the development in the global system. Good Living / Living Well is a concept under construction, hence the importance of progress in the identification of variables and indicators for its measurement.

  4. Ingénierie de la maintenance De la conception à l'exploitation d'un bien

    CERN Document Server

    Francastel, Jean-Claude

    2003-01-01

    La maintenance a évolué : d’abord confinée à l’entretien des équipements “réparer“ les pannes puis élargie à leur surveillance “prévoir” les pannes elle est intégrée aujourd’hui dès la phase de conception du produit avec notamment le concept de “maintenabilité” du produit. L’ingénierie de maintenance désigne ce processus d’accompagnement d’un bien industriel durant toutes les phases de son cycle de vie de la conception au démantèlement qui permet d’optimiser l’exploitation de ce bien et son coût global life cycle cost. Cet ouvrage décrit les différentes phases du cycle de vie en exposant les techniques qui permettent d’intégrer à chaque étape les concepts de maintenance.

  5. Quantum dots: Rethinking the electronics

    Science.gov (United States)

    Bishnoi, Dimple

    2016-05-01

    In this paper, we demonstrate theoretically that the Quantum dots are quite interesting for the electronics industry. Semiconductor quantum dots (QDs) are nanometer-scale crystals, which have unique photo physical, quantum electrical properties, size-dependent optical properties, There small size means that electrons do not have to travel as far as with larger particles, thus electronic devices can operate faster. Cheaper than modern commercial solar cells while making use of a wider variety of photon energies, including "waste heat" from the sun's energy. Quantum dots can be used in tandem cells, which are multi junction photovoltaic cells or in the intermediate band setup. PbSe (lead selenide) is commonly used in quantum dot solar cells.

  6. Quadra-Quantum Dots and Related Patterns of Quantum Dot Molecules: Basic Nanostructures for Quantum Dot Cellular Automata Application

    Directory of Open Access Journals (Sweden)

    Somsak Panyakeow

    2010-10-01

    Full Text Available Laterally close-packed quantum dots (QDs called quantum dot molecules (QDMs are grown by modified molecular beam epitaxy (MBE. Quantum dots could be aligned and cross hatched. Quantum rings (QRs created from quantum dot transformation during thin or partial capping are used as templates for the formations of bi-quantum dot molecules (Bi-QDMs and quantum dot rings (QDRs. Preferable quantum dot nanostructure for quantum computation based on quantum dot cellular automata (QCA is laterally close-packed quantum dot molecules having four quantum dots at the corners of square configuration. These four quantum dot sets are called quadra-quantum dots (QQDs. Aligned quadra-quantum dots with two electron confinements work like a wire for digital information transmission by Coulomb repulsion force, which is fast and consumes little power. Combination of quadra-quantum dots in line and their cross-over works as logic gates and memory bits. Molecular Beam Epitaxial growth technique called 'Droplet Epitaxy' has been developed for several quantum nanostructures such as quantum rings and quantum dot rings. Quantum rings are prepared by using 20 ML In-Ga (15:85 droplets deposited on a GaAs substrate at 390'C with a droplet growth rate of 1ML/s. Arsenic flux (7'8'10-6Torr is then exposed for InGaAs crystallization at 200'C for 5 min. During droplet epitaxy at a high droplet thickness and high temperature, out-diffusion from the centre of droplets occurs under anisotropic strain. This leads to quantum ring structures having non-uniform ring stripes and deep square-shaped nanoholes. Using these peculiar quantum rings as templates, four quantum dots situated at the corners of a square shape are regrown. Two of these four quantum dots are aligned either or, which are preferable crystallographic directions of quantum dot alignment in general.

  7. Hydrophobin-Encapsulated Quantum Dots.

    Science.gov (United States)

    Taniguchi, Shohei; Sandiford, Lydia; Cooper, Maggie; Rosca, Elena V; Ahmad Khanbeigi, Raha; Fairclough, Simon M; Thanou, Maya; Dailey, Lea Ann; Wohlleben, Wendel; von Vacano, Bernhard; de Rosales, Rafael T M; Dobson, Peter J; Owen, Dylan M; Green, Mark

    2016-02-01

    The phase transfer of quantum dots to water is an important aspect of preparing nanomaterials that are suitable for biological applications, and although numerous reports describe ligand exchange, very few describe efficient ligand encapsulation techniques. In this report, we not only report a new method of phase transferring quantum dots (QDs) using an amphiphilic protein (hydrophobin) but also describe the advantages of using a biological molecule with available functional groups and their use in imaging cancer cells in vivo and other imaging applications.

  8. Quantum Dots in Cell Biology

    OpenAIRE

    Barroso, Margarida M.

    2011-01-01

    Quantum dots are semiconductor nanocrystals that have broad excitation spectra, narrow emission spectra, tunable emission peaks, long fluorescence lifetimes, negligible photobleaching, and ability to be conjugated to proteins, making them excellent probes for bioimaging applications. Here the author reviews the advantages and disadvantages of using quantum dots in bioimaging applications, such as single-particle tracking and fluorescence resonance energy transfer, to study receptor-mediated t...

  9. Quantum dots in cell biology.

    Science.gov (United States)

    Barroso, Margarida M

    2011-03-01

    Quantum dots are semiconductor nanocrystals that have broad excitation spectra, narrow emission spectra, tunable emission peaks, long fluorescence lifetimes, negligible photobleaching, and ability to be conjugated to proteins, making them excellent probes for bioimaging applications. Here the author reviews the advantages and disadvantages of using quantum dots in bioimaging applications, such as single-particle tracking and fluorescence resonance energy transfer, to study receptor-mediated transport.

  10. Fuzzy dot ideals and fuzzy dot H-ideals of BCH-algebras

    Institute of Scientific and Technical Information of China (English)

    PENG Jia-yin

    2008-01-01

    The notions of fuzzy dot ideals and fuzzy dot H-ideals in BCH-algebras are intro duced,several appropriate examples are provided,and their some properties are investigated.The relations among fuzzy ideal,fuzzy H-ideal,fuzzy dot ideal and fuzzy dot H-ideals in BCH algebras are discussed,several equivalent depictions of fuzzy dot ideal are obtained. How to deal with the homomorphic image and inverse image of fuzzy dot ideals (fuzzy dot H-ideals) are studied. The relations between a fuzzy dot ideal (fuzzy dot H-ideal) in BCH-algebras and a fuzzy dot ideal (fuzzy dot H-ideal) in the product algebra of BCH-algebras are given.

  11. INDUSTRIA DE BIENES DE EQUIPO DE LA ECONOMÍA ESPAÑOLA: INSERCIÓN COMERCIAL Y CAMBIO ESTRUCTURAL

    Directory of Open Access Journals (Sweden)

    Fernando Luengo

    2011-01-01

    Full Text Available El texto examina el comercio exterior de la industria de bienes de equipo de la economía española en el entorno comunitario. Dicho análisis se realiza a partir de la evolución de un conjunto de indicadores reveladores de la calidad de la inserción comercial, el nivel tecnológico y la posición de gama. La principal conclusión es que, aun aceptando la diversidad de posiciones y trayectorias observadas en la industria, parece que ésta ocupa un espacio relativamente subordinado, instalada en segmentos de mercado de mediabaja tecnología y gama.

  12. Entendiendo el flujo de bienes intermedios en el nuevo siglo: hechos estilizados para explicar la especialización vertical

    OpenAIRE

    Domínguez, Juan Pablo

    2015-01-01

    El comercio mundial ha mostrado tasas de crecimiento constante durante los últimos 30 años. El proceso de globalización y la entrada al mercado de nuevas economías, como en el caso de China, ha dado una nueva dinámica del comercio en el sistema. Ésto ha tenido repercusiones en muchos ámbitos del mundo económico y político, muchos han acusado a China de tener competitividad "excesiva" en sus productos, que a su vez ha afectado a otras economías. Este trabajo analiza el flujo de bienes intermed...

  13. Single to quadruple quantum dots with tunable tunnel couplings

    Energy Technology Data Exchange (ETDEWEB)

    Takakura, T.; Noiri, A.; Obata, T.; Yoneda, J.; Yoshida, K. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Otsuka, T.; Tarucha, S. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); RIKEN, Center for Emergent Matter Science, 3-1 Wako-shi, Saitama 351-0198 (Japan)

    2014-03-17

    We prepare a gate-defined quadruple quantum dot to study the gate-tunability of single to quadruple quantum dots with finite inter-dot tunnel couplings. The measured charging energies of various double dots suggest that the dot size is governed by the gate geometry. For the triple and quadruple dots, we study the gate-tunable inter-dot tunnel couplings. For the triple dot, we find that the effective tunnel coupling between side dots significantly depends on the alignment of the center dot potential. These results imply that the present quadruple dot has a gate performance relevant for implementing spin-based four-qubits with controllable exchange couplings.

  14. Les Nations unies et les biens publics mondiaux : contributions historiques et défis à venir

    Directory of Open Access Journals (Sweden)

    Bruce Jenks

    2012-04-01

    Full Text Available Cet article explore la thèse selon laquelle la contribution la plus importante de l’Organisation des Nations unies (ONU à la production de biens publics mondiaux a été son rôle dans l’instauration d’espaces et de capacités permettant de créer des valeurs communes. Débutant par la Charte elle-même, l’auteur retrace l’évolution de cette contribution à travers différentes phases historiques. Il analyse l’impact de la mondialisation sur le rôle des Nations unies ; il identifie notamment la qualité de la perméabilité en tant que produit de la mondialisation, ce qui est essentiel à la compréhension des défis actuels auxquels font face les Nations unies et également au cœur du programme sur les biens publics mondiaux (BPM. L’article examine brièvement, sous cet angle, l’évolution du rôle des Nations unies dans les domaines de la paix et de la sécurité, des droits de l’homme et de la coopération au développement. En conclusion sont identifiés huit leviers de changement qui détermineront la faculté des Nations unies à contribuer de manière substantielle aux BPM : l’instauration de normes et de valeurs communes, la qualité de la direction, l’amélioration de la gouvernance, un réalignement institutionnel, des financements innovants, le renforcement de la consolidation des instruments juridiques, la concentration sur des points stratégiques et le pouvoir des réseaux.

  15. Transport and bioaccumulation of polychlorinated dibenzo-p-dioxins and dibenzofurans at the Bien Hoa Agent Orange hotspot in Vietnam.

    Science.gov (United States)

    Van Thuong, Nguyen; Hung, Nguyen Xuan; Mo, Nguyen Thi; Thang, Nguyen Manh; Huy, Pham Quang; Van Binh, Hoang; Nam, Vu Duc; Van Thuy, Nguyen; Son, Le Ke; Minh, Nguyen Hung

    2015-10-01

    The Bien Hoa airbase (south of Vietnam) is known as one of the Agent Orange hotspots which have been seriously contaminated by Agent Orange/dioxin during the Vietnam War. Hundreds of samples including soil, sediment and fish were collected at the Bien Hoa Agent Orange hotspot for assessment of the environmental contamination caused by dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The toxicity equivalency quotient (TEQ) concentration of PCDD/Fs in soil and sediment varied from 7.6 to 962,000 and 17 to 4860 pg/g dry wt, respectively, implying very high contamination of PCDD/Fs in several areas. PCDD/F levels in fish ranged between 1.8 and 288 pg/g TEQ wet wt and was generally higher than advisory guidelines for food consumption. 2,3,7,8-Tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TCDD) contributed 66-99 % of TEQ for most of the samples, suggesting 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) from Agent Orange as the major source of the contamination. The vertical transport of PCDD/Fs was observed in soil column with high TEQ levels above 1000 pg/g dry wt (Vietnamese limit for necessary remediation activities- TCVN 8183:2009 (2009)) even at a depth of 1.8 m. The vertical transport of PCDD/Fs has probably mainly taken place during the "Ranch Hand" defoliant spray activities due to the leaks and spills of phenoxy herbicides and solvents. The congener patterns suggest that transports of PCDD/Fs by weathering processes have led to their redistribution in the low-land areas. Also, an estimate for the total volume of contaminated soil requiring remediation to meet Vietnamese regulatory limits is provided.

  16. Optically active quantum dots

    Science.gov (United States)

    Gerard, Valerie; Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii K.

    2015-10-01

    The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.

  17. Le bien commun : une intention éthique entre la loi du marché et l’individualisme

    OpenAIRE

    Beauchemin, Jacques

    2016-01-01

    Considérer le bien commun du point de vue des objets qu’il recouvre conduit à considérer un ensemble de « biens sociaux » associés à la nature biologique, sociale et politique des individus en société. Or la définition du bien commun ne réside pas seulement dans les objets auxquels on peut l’associer mais surtout dans la capacité collective à faire de la société un projet éthique de vivre ensemble. Ainsi, l’atomisation de la société que provoquent la marchandisation et l’individualisme contre...

  18. La protección de bienes urbanos. Avances en la política pública de Medellín

    Directory of Open Access Journals (Sweden)

    Clara In��s Atehortúa-Arredondo

    2010-12-01

    Full Text Available La problemática de la protección de bienes en el país es una pregunta obligatoria para quienes tienen dentro de su labor el reconocimiento, la restitución y la reparación de las víctimas del desplazamiento forzado. Uno de los puntos que deben analizarse dentro de esta problemática es lo concerniente a la protección de bienes urbanos y cuya responsabilidad está en cabeza de los municipios. El desarrollo de una política pública por parte de la ciudad de Medellín para la protección de bienes es un avance significativo para la construcción de protocolos y para la reivindicación de derechos de quienes han abandonado por causa de la violencia o han sido despojados de sus viviendas en lo urbano.

  19. Bienes de titularidad pública: Patrimoniales y de dominio público. Una aproximación al sistema español

    OpenAIRE

    Luís Hernando Van-Strahlen-Fajardo

    2010-01-01

    Se realiza en este texto una aproximación puntual al régimen jurídico de los bienes de titularidad pública en España. Se comienza por la tradicional distinción entre bienes de dominio público y bienes patrimoniales o privados del Estado, donde se evidencia la ambigua frontera que separa al derecho público y al derecho privado. Luego se describen con mayor detenimiento las formas, las técnicas y los modos jurídicos para la adquisición, la enajenación, la cesión, la transferencia y la protecció...

  20. Chiral Graphene Quantum Dots.

    Science.gov (United States)

    Suzuki, Nozomu; Wang, Yichun; Elvati, Paolo; Qu, Zhi-Bei; Kim, Kyoungwon; Jiang, Shuang; Baumeister, Elizabeth; Lee, Jaewook; Yeom, Bongjun; Bahng, Joong Hwan; Lee, Jaebeom; Violi, Angela; Kotov, Nicholas A

    2016-02-23

    Chiral nanostructures from metals and semiconductors attract wide interest as components for polarization-enabled optoelectronic devices. Similarly to other fields of nanotechnology, graphene-based materials can greatly enrich physical and chemical phenomena associated with optical and electronic properties of chiral nanostructures and facilitate their applications in biology as well as other areas. Here, we report that covalent attachment of l/d-cysteine moieties to the edges of graphene quantum dots (GQDs) leads to their helical buckling due to chiral interactions at the "crowded" edges. Circular dichroism (CD) spectra of the GQDs revealed bands at ca. 210-220 and 250-265 nm that changed their signs for different chirality of the cysteine edge ligands. The high-energy chiroptical peaks at 210-220 nm correspond to the hybridized molecular orbitals involving the chiral center of amino acids and atoms of graphene edges. Diverse experimental and modeling data, including density functional theory calculations of CD spectra with probabilistic distribution of GQD isomers, indicate that the band at 250-265 nm originates from the three-dimensional twisting of the graphene sheet and can be attributed to the chiral excitonic transitions. The positive and negative low-energy CD bands correspond to the left and right helicity of GQDs, respectively. Exposure of liver HepG2 cells to L/D-GQDs reveals their general biocompatibility and a noticeable difference in the toxicity of the stereoisomers. Molecular dynamics simulations demonstrated that d-GQDs have a stronger tendency to accumulate within the cellular membrane than L-GQDs. Emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.

  1. Quantum-dot emitters in photonic nanostructures

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Stobbe, Søren; Lodahl, Peter

    2010-01-01

    The spontaneous emission from self-assembled semiconductor quantum dots is strongly influenced by the environment in which they are placed. This can be used to determine fundamental optical properties of the quantum dots as well as to manipulate and control the quantum-dot emission itself....

  2. Beer's law in semiconductor quantum dots

    CERN Document Server

    Adamashvili, G T

    2010-01-01

    The propagation of a coherent optical linear wave in an ensemble of semiconductor quantum dots is considered. It is shown that a distribution of transition dipole moments of the quantum dots changes significantly the polarization and Beer's absorption length of the ensemble of quantum dots. Explicit analytical expressions for these quantities are presented.

  3. Membrane analysis with amphiphilic carbon dots.

    Science.gov (United States)

    Nandi, Sukhendu; Malishev, Ravit; Parambath Kootery, Kaviya; Mirsky, Yelena; Kolusheva, Sofiya; Jelinek, Raz

    2014-09-14

    Newly-synthesized amphiphilic carbon dots were used for spectroscopic analysis and multicolour microscopic imaging of membranes and live cells. We show that Förster resonance energy transfer (FRET) occurred from the amphiphilic carbon dots to different membrane-associated fluorescence acceptors. The amphiphilic carbon dots enabled imaging of membrane disruption by the beta-amyloid peptide.

  4. Determinación de los precios implícitos en bienes inmuebles : una alternativa a la modelización hedónica

    OpenAIRE

    2004-01-01

    RESUMEN Recientemente un nuevo enfoque para estimar el valor de bienes inmuebles está siendo cada vez más usado. Para ello se usan atributos internos del bien, y externos, del entorno, pues ambos son percibidos de forma diferente en el mercado. Así pues, propiedades con nivel de precios similar son consideradas como claramente diferenciadas en los mercados inmobiliarios. Las técnicas de Inteligencia Arti cial proporcionan nuevas posibilidades, en comparación con la modelización econométrica ...

  5. Administración económica del distrito inquisitorial de Valencia: la receptoría de bienes confiscados (1482-1493)

    OpenAIRE

    Tomás Botella, Bernardo

    2016-01-01

    El objeto de esta tesis doctoral es la receptoría de bienes confiscados de la Inquisición de Valencia, su estructura burocrática y sus procedimientos de actuación sobre la sociedad valenciana bajomedieval. Esta oficina se encargaba de ejecutar el secuestro y confiscación del patrimonio de los herejes condenados, así como de gestionar y liquidar dichos bienes una vez incorporados al fisco regio. Además, se ha analizado la evolución institucional que experimentó el Santo Oficio durante el perio...

  6. "Penuria pauperum clamat".Discursos letrados sobre los bienes eclesiásticos (Siglos XII-XVI): doctrinas ideales y realidades típicas

    OpenAIRE

    Rafael M. Pérez García

    2014-01-01

    Este trabajo estudia los orígenes y el desarrollo de los discursos letrados sobre los bienes eclesiásticos entre los siglos XII y XVI. Generados en el marco de los procesos reformistas que se producen en la Iglesia durante este arco de tiempo, estos discursos acabaron conformando las mentalidades sociales sobre el clérigo ideal y su relación con los bienes materiales. This article studies the origins and development of the highbrow literature about the ecclesiastical properties...

  7. Costes de transacción vs costes de jerarquía en la provisión de bienes: Una interpretación smithiana

    OpenAIRE

    Trincado Aznar, Estrella

    2007-01-01

    En la teoría de Adam Smith, las jerarquías económicas nunca pueden reducir los costes de transacción del mercado. Para demostrarlo, el artículo estudia la definición de libertad Smithiana, que lleva a que cualquier imposición sobre la actividad independiente y creativa sea «costosa». También explica el tratamiento del tema de la provisión de bienes privados y públicos en la Riqueza de las Naciones. Por tanto, por un lado se describe la naturaleza de la empresa, que provee bienes privados, y p...

  8. Nanoscale quantum-dot supercrystals

    Science.gov (United States)

    Baimuratov, Anvar S.; Turkov, Vadim K.; Rukhlenko, Ivan D.; Baranov, Alexander V.; Fedorov, Anatoly V.

    2013-09-01

    We develop a theory allowing one to calculate the energy spectra and wave functions of collective excitations in twoand three-dimensional quantum-dot supercrystals. We derive analytical expressions for the energy spectra of twodimensional supercrystals with different Bravias lattices, and use them to analyze the possibility of engineering the supercrystals' band structure. We demonstrate that the variation of the supercrystal's parameters (such as the symmetry of the periodic lattice and the properties of the quantum dots or their environment) enables an unprecedented control over its optical properties, thus paving a way towards the development of new nanophotonics materials.

  9. El castellano bien templado

    OpenAIRE

    Sáenz, Miguel

    2009-01-01

    Este artículo se sirve de la música para establecer un paralelismo entre ésta y la traducción, pues si la traducción es una interpretación (musical) de un texto, puede haber innumerables traducciones válidas, pudiendo haber alguna “de referencia”. Además, se plantea que las facultades son como conservatorios donde los futuros traductores estudian técnicas y aprenden fundamentos teóricos (que compara con el solfeo, la armonía y la composición) y que las traducciones “envejecen” porque su es...

  10. Spin storage in quantum dot ensembles and single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Dominik

    2009-10-15

    This thesis deals with the investigation of spin relaxation of electrons and holes in small ensembles of self-assembled quantum dots using optical techniques. Furthermore, a method to detect the spin orientation in a single quantum dot was developed in the framework of this thesis. A spin storage device was used to optically generate oriented electron spins in small frequency selected quantum dot ensembles using circularly polarized optical excitation. The spin orientation can be determined by the polarization of the time delayed electroluminescence signal generated by the device after a continuously variable storage time. The degree of spin polarized initialization was found to be limited to 0.6 at high magnetic fields, where anisotropic effects are compensated. The spin relaxation was directly measured as a function of magnetic field, lattice temperature and s-shell transition energy of the quantum dot by varying the spin storage time up to 30 ms. Very long spin lifetimes are obtained with a lower limit of T{sub 1}=20 ms at B=4 T and T=1 K. A strong magnetic field dependence T{sub 1}{proportional_to}B{sup -5} has been observed for low temperatures of T=1 K which weakens as the temperature is increased. In addition, the temperature dependence has been determined with T{sub 1}{proportional_to}T{sup -1}. The characteristic dependencies on magnetic field and temperature lead to the identification of the spin relaxation mechanism, which is governed by spin-orbit coupling and mediated by single phonon scattering. This finding is qualitatively supported by the energy dependent measurements. The investigations were extended to a modified device design that enabled studying the spin relaxation dynamics of heavy holes in self-assembled quantum dots. The measurements show a polarization memory effect for holes with up to 0.1 degree of polarization. Furthermore, investigations of the time dynamics of the hole spin relaxation reveal surprisingly long lifetimes T{sub 1}{sup h

  11. El consumo de bienes religiosos. Una introducción económica al caso español

    Directory of Open Access Journals (Sweden)

    Brañas-Garza, Pablo

    2003-08-01

    Full Text Available This paper uses the Economic of Religion issues to explore Spanish religious behaviour. Under this microeconomic framework religious practise is considered "rational" using Azzi-Ehrenberg (1975 arguments: salvation, social and professional motives. We test if that hypotheses may explain Spanish religious activity. To this end we run descriptive and multivariate analysis that allows us to conclude the following: theoretical models well perform Spanish data; gender, ageing, family size and education are positive determinant of church-attendance; the influence of parents behaviour on children religious activity.

    Este trabajo explora el comportamiento religioso de los españoles desde el enfoque de la Economía de la Religión. En un marco microeconómico y utilizando los argumentos de Azzi- Ehrenberg (1975 —motivo salvación, consumo y profesional—, la práctica religiosa resulta racional. En esta investigación estudiamos si estas hipótesis pueden explicar el comportamiento religioso de los españoles. Para ello se realizan análisis descriptivos y multivariantes que nos permiten concluir que: los modelos teóricos explican bien los datos españoles; que el sexo, la edad, el tamaño de la familia y la educación son determinantes positivos de la asistencia a iglesia; que el ejemplo de los padres influye en la actividad religiosa actual de los hijos.

  12. Environmental health risk assessment of dioxin exposure through foods in a dioxin hot spot-Bien Hoa City, Vietnam.

    Science.gov (United States)

    Tuyet-Hanh, Tran Thi; Vu-Anh, Le; Ngoc-Bich, Nguyen; Tenkate, Thomas

    2010-05-01

    This study used the Australian Environmental Health Risk Assessment Framework to assess the human health risk of dioxin exposure through foods for local residents in two wards of Bien Hoa City, Vietnam. These wards are known hot-spots for dioxin and a range of stakeholders from central government to local levels were involved in this process. Publications on dioxin characteristics and toxicity were reviewed and dioxin concentrations in local soil, mud, foods, milk and blood samples were used as data for this risk assessment. A food frequency survey of 400 randomly selected households in these wards was conducted to provide data for exposure assessment. Results showed that local residents who had consumed locally cultivated foods, especially fresh water fish and bottom-feeding fish, free-ranging chicken, duck, and beef were at a very high risk, with their daily dioxin intake far exceeding the tolerable daily intake recommended by the WHO. Based on the results of this assessment, a multifaceted risk management program was developed and has been recognized as the first public health program ever to have been implemented in Vietnam to reduce the risks of dioxin exposure at dioxin hot-spots.

  13. Environmental Health Risk Assessment of Dioxin Exposure through Foods in a Dioxin Hot Spot—Bien Hoa City, Vietnam

    Directory of Open Access Journals (Sweden)

    Tran Thi Tuyet-Hanh

    2010-05-01

    Full Text Available This study used the Australian Environmental Health Risk Assessment Framework to assess the human health risk of dioxin exposure through foods for local residents in two wards of Bien Hoa City, Vietnam. These wards are known hot-spots for dioxin and a range of stakeholders from central government to local levels were involved in this process. Publications on dioxin characteristics and toxicity were reviewed and dioxin concentrations in local soil, mud, foods, milk and blood samples were used as data for this risk assessment. A food frequency survey of 400 randomly selected households in these wards was conducted to provide data for exposure assessment. Results showed that local residents who had consumed locally cultivated foods, especially fresh water fish and bottom-feeding fish, free-ranging chicken, duck, and beef were at a very high risk, with their daily dioxin intake far exceeding the tolerable daily intake recommended by the WHO. Based on the results of this assessment, a multifaceted risk management program was developed and has been recognized as the first public health program ever to have been implemented in Vietnam to reduce the risks of dioxin exposure at dioxin hot-spots.

  14. Créations graphiques réussissez vos brochures, logos, pages web, newsletters, flyers, et bien plus encore !

    CERN Document Server

    McWade, John

    2010-01-01

    Dans cet ouvrage, qui regroupe un florilège des meilleurs projets professionnels publiés dans son célèbre magazine de graphisme, Before & After, John McWade offre une présentation approfondie des principes de base du graphisme, avant de partager concrètement techniques et procédés. Dans un style simple et convivial, il analyse différentes créations graphiques abouties – brochures, lettres d'information, sites web, cartes de visite et autres supports visuels – et explique le pourquoi et le comment de leur réussite. À votre tour, inspirez-vous de ces exemples et employez ces mêmes techniques à l'envie pour améliorer vos propres documents. Vous apprendrez à: rogner des photos pour parfaire leur fonction et leur signification; attirer le regard du lecteur à l'emplacement souhaité à l'aide de huit solutions différentes; travailler sur les composants de base de la création graphique, tels que le trait, la forme, la direction, le mouvement, la mise à l'échelle, la couleur, et bien d'a...

  15. Los expedientes de incautación de bienes. El caso del partido judicial de Aracena (Huelva, 1936-1939

    Directory of Open Access Journals (Sweden)

    Pedro Jesús Feria Vázquez

    2009-12-01

    Full Text Available En este trabajo se expone cómo la justicia en el bando nacional durante la Guerra Civil fue una herramienta en manos de las tropas del general Franco, ejerciéndose una política de represión económica a fin de financiar los gastos de la guerra y del aparato estatal que iban construyendo. Es lo que podríamos denominar como represión económica, o cómo el franquismo, además de asesinar o encarcelar a los opositores, les despojó de sus bienes, con la intención de anularles completamente y de paso financiar su cruzada.____________________ABSTRACT:This work presents how during the Civil War justice in the nationalist camp was a tool in the hands of general Franco’s troops, who exercised a policy of economic repression in order to cover the costs of the war and the state apparatus they were creating. This is what we can call economical repression, or how Franco’s regime, in addition to assassinating or imprisoning the opponents, stripped them of all they had, with an intention to eliminate them completely and at the same time finance their own crusade.

  16. La sucesión a los bienes de Juan Antonio Llorente, en París

    Directory of Open Access Journals (Sweden)

    de la Lama, Enrique

    2003-06-01

    Full Text Available Llorente, one of the most famous critics of the Spanish Inquisition, «afrancesado » in top responsibility and well known in his own physical feature wich Goya made of him, died without leaving his last will. The present work studies in detail the notary documents referring to «succesio ab intestato», wich permit to know his library, his personal belongings as well as information about an illegitimate daughter born in France during his exile.

    Llorente, uno de los más afamados críticos de la Inquisición de España, afrancesado de alta responsabilidad y bien conocido en su mismo semblante físico por el retrato que le hizo Goya, falleció sin hacer testamento. El presente trabajo estudia detalladamente los documentos notariales de la sucesión «ab intestato», que permiten conocer su biblioteca y sus enseres personales, así como la noticia de una hija natural nacida en Francia durante su exilio.

  17. Polymer-coated quantum dots

    NARCIS (Netherlands)

    Tomczak, Nikodem; Liu, Rongrong; Vancso, Julius G.

    2013-01-01

    Quantum Dots (QDs) are semiconductor nanocrystals with distinct photophysical properties finding applications in biology, biosensing, and optoelectronics. Polymeric coatings of QDs are used primarily to provide long-term colloidal stability to QDs dispersed in solutions and also as a source of addit

  18. DOT strategies versus orbiter strategies

    NARCIS (Netherlands)

    Rutten, R.J.

    2001-01-01

    The Dutch Open Telescope is a high-resolution solar imager coming on-line at La Palma. The definition of the DOT science niche, strategies, and requirements resemble Solar Orbiter considerations and deliberations. I discuss the latter in the light of the former, and claim that multi-line observation

  19. Nuclear Spins in Quantum Dots

    NARCIS (Netherlands)

    Erlingsson, S.I.

    2003-01-01

    The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis, stro

  20. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-10

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  1. Variants, Layers of Authorial Intervention, and Texts in Lope de Vega’s La buena guarda and La encomienda bien guardada autograph manuscript

    Directory of Open Access Journals (Sweden)

    Stefania Capoia

    2014-01-01

    Full Text Available In this article I study, analyze and classify the variant readings and the different layers of authorial intervention that appear in Lope de Vega’s La buena guarda and La encomienda bien guardada manuscript. I contend that the second version of the work should be edited, a possibility thus far neglected by modern editors.

  2. Spin transport through quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Lima, A.T. da Cunha; Anda, Enrique V. [Pontificia Univ. Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil)

    2003-07-01

    Full text: We investigate the spin polarized transport properties of a nanoscopic device constituted by a quantum dot connected to two leads. The electrical current circulates with a spin polarization that is modulated via a gate potential that controls the intensity of the spin-orbit coupling, the Rashba effect. We study a polarized field-effect transistor when one of its parts is constituted by a small quantum dot, which energies are controlled by another gate potential operating inside the confined region. The high confinement and correlation suffered by the charges inside the dot gives rise to novel phenomena. We show that through the manipulation of the gate potential applied to the dot it is possible to control, in a very efficient way, the intensity and polarization of the current that goes along the system. Other crucial parameters to be varied in order to understand the behavior of this system are the intensity of the external applied electric and magnetic field. The system is represented by the Anderson Impurity Hamiltonian summed to a spin-orbit interaction, which describes the Rashba effect. To obtain the current of this out-of-equilibrium system we use the Keldysh formalism.The solution of the Green function are compatible with the Coulomb blockade regime. We show that under the effect of a external magnetic field, if the dot is small enough the device operates as a complete spin filter that can be controlled by the gate potential. The behavior of this device when it is injected into it a polarized current and modulated by the Rashba effect is as well studied. (author)

  3. Episodes of brittle deformation within the Dien Bien Phu Fault zone, Vietnam: Evidence from K-Ar age dating of authigenic illite

    Science.gov (United States)

    Bui, Hoang Bac; Ngo, Xuan Thanh; Khuong, The Hung; Golonka, Jan; Nguyen, Tien Dung; Song, Yungoo; Itaya, Tetsumaru; Yagi, Koshi

    2017-01-01

    Constraining the timing of fault zone origin and movement history is of fundamental geotectonic importance to understand the evolution and processes of the brittle fault structures. The authors present in this paper authigenic illite K-Ar age data from the fault gouge samples, collected from the Dien Bien Phu Fault (DBPF) in the Dien Bien province, Vietnam as well as in a major strike-slip fault zone in South-East Asia; all of which played important roles in the structural formation and geotectonic development of northwestern Vietnam. The gouge fault samples were separated into four grain-size fractions (groups, from 26 to 29 Ma and 130 Ma. The timing of the fault movements is defined at 26 ± 0.24 Ma, 29 ± 0.61 Ma, 130.1 ± 1.27 Ma and 130.7 ± 1.29 Ma. This indicates that the Dien Bien Phu Fault underwent two movements, first in the Early Cretaceous, with an age of about 130 Ma and second in the Oligocene (Paleogene), with an age of about 26-29 Ma. The ductile deformation of the DBPF terminated during the Early Cretaceous. These studies also indicate slow exhumation of the Dien Bien granitoid complex during the Cretaceous times. The Oligocene ages indicate that the DBPF had been reactivated by the SE extrusion and clock-wise rotation of the Indochina block, caused by the collision of the Indian and Eurasian plates. This tectonic event led to the DBPF brittle-sinistral movement, causing the exhumation phase along the fault. This movement period (ca. 26-29 Ma) is coexistent with 600-700 km sinistral shearing along the Red River-Ailao Shan fault. This is the first report determining the absolute age constraints of multi-activated tectonic events, affecting the Dien Bien Phu Fault using the K-Ar dating method for the gouge samples.

  4. Modelo para la inflación básica de bienes transables y no transables en Colombia

    Directory of Open Access Journals (Sweden)

    José Luis Torres Trespalacios

    2015-12-01

    Full Text Available En este trabajo se estiman modelos de corto plazo para pronosticar la inflación de bienes transables y no transables en Colombia. Estos modelos no existían en el Banco Central antes de 2004 y son de gran utilidad para la toma de decisiones de política monetaria. También se evalúan los beneficios, en términos de análisis y de capacidad pronóstico, de utilizar métodos que capturen la posible no linealidad de la curva de Phillips en los datos colombianos. Aunque existen diferentes razones que justifican una relación no lineal de corto plazo entre producto e inflación, cada una de ellas sugiere una forma diferente para la curva. Por esta razón, se utilizan redes neuronales artificiales (ANN y los mínimos cuadrados flexibles (FLS, procedimientos que tienen la gran ventaja de que no imponen de antemano ninguna forma funcional que pueda sesgar los resultados. Una vez se hace la estimación de los modelos de inflación de transables y de no transables, se comparan los pronósticos de estos dos modelos no lineales con los de dos estimaciones lineales , se analizan las funciones de impulso respuesta de cada uno de los modelos y además se realiza una prueba de no linealidad. Se encuentra que la curva de Phillips en Colombia podria ser no lineal y por tanto, resulta pertinente considerar modelos no lineales para su estimación. Finalmente, con estos modelos se intenta explicar el proceso de desinflación que ha vivido la economía colombiana en los últimos años tanto en la inflación de transables, como en la de no transables.

  5. Manipulación mediática, identidad juvenil y prostitución de un bien necesario

    Directory of Open Access Journals (Sweden)

    Alexander Mosquera

    2007-01-01

    Full Text Available Algo que identifi ca al joven de hoy es la telefonía móvil, una nueva tecnología que invade todas las esferas de lavida pública y privada, cuya presencia se hace sentir a través de una multiplicidad de “ring-tones”. Este trabajo tienecomo objetivo general describir la interrelación que se da entre la manipulación de los medios a través del discursopublicitario sobre celulares, la construcción de la identidad juvenil y la prostitución de lo que otrora fuera un bien necesariocomo el teléfono. Se abordó un corpus compuesto por varios avisos publicitarios que circularon en los diariosvenezolanos El Nacional, La Verdad y Panorama durante agosto de 2005, desde la perspectiva teórico-metodológicade la semiótica crítica de González de Ávila y de la semiótica de la cultura de Lotman. También se utilizaron algunosaportes de Magariños de Morentin relacionados con la semiótica de los mensajes publicitarios, así como los de Caro Almela, Bourdieu, Pasquali y Eco sobre los mass-media. Los resultados revelaron una manipulación mediática a través del discurso publicitario, dirigida a crear la urgente necesidad de poseer un celular, porque éste es el signo-mercancía con el cual se identifi ca el joven actual. Una conclusión preliminar indica que la no-posesión de ese aparato hace aparecer al joven como un “excluido” de ese mundo de la telefonía móvil.

  6. Carbon dots as antioxidants and prooxidants.

    Science.gov (United States)

    Christensen, Ingeborg Lie; Sun, Ya-Ping; Juzenas, Petras

    2011-10-01

    In this study we report the effect of classical CdSe/ZnS quantum dots and novel spherical carbon dots on generation of singlet oxygen and other reactive oxygen species (ROS) in aqueous solutions in vitro. Free radicals were initiated either chemically using 2,2'-azodiisobutyramidine dihydrochloride (AAPH) or by radiation with a blue light source emitting 390-470 nm (peak 420 nm). Two reagents, dihydrorhodamine 123 (Dhr123) and singlet oxygen sensor green (SOSG), were used as radical probes. Quantum dots and carbon dots inhibited oxidation of the radical probes under decomposition of AAPH. However, when subjected to the blue light both the quantum dots and carbon dots induced oxidation of Dhr123 to a greater extent than SOSG in water. Generation of singlet oxygen was remarkably enhanced in deuterium oxide solutions while oxidation of Dhr123 remained unchanged. For comparison, traditional photosensitizer protoporphyrin IX mainly induced oxidation of SOSG in water. In conclusion, upon external radiation carbon dots or quantum dots generate reactive oxygen species acting as prooxidants. Carbon dots or quantum dots also scavenge free radicals that are generated chemically by an azo compound. Such dual properties of these nanoparticles can be used for photodynamic and photocatalytic or antioxidant applications.

  7. Probing silicon quantum dots by single-dot techniques

    Science.gov (United States)

    Sychugov, Ilya; Valenta, Jan; Linnros, Jan

    2017-02-01

    Silicon nanocrystals represent an important class of non-toxic, heavy-metal free quantum dots, where the high natural abundance of silicon is an additional advantage. Successful development in mass-fabrication, starting from porous silicon to recent advances in chemical and plasma synthesis, opens up new possibilities for applications in optoelectronics, bio-imaging, photovoltaics, and sensitizing areas. In this review basic physical properties of silicon nanocrystals revealed by photoluminescence spectroscopy, lifetime, intensity trace and electrical measurements on individual nanoparticles are summarized. The fabrication methods developed for accessing single Si nanocrystals are also reviewed. It is concluded that silicon nanocrystals share many of the properties of direct bandgap nanocrystals exhibiting sharp emission lines at low temperatures, on/off blinking, spectral diffusion etc. An analysis of reported results is provided in comparison with theory and with direct bandgap material quantum dots. In addition, the role of passivation and inherent interface/matrix defects is discussed.

  8. Dot-in-Well Quantum-Dot Infrared Photodetectors

    Science.gov (United States)

    Gunapala, Sarath; Bandara, Sumith; Ting, David; Hill, cory; Liu, John; Mumolo, Jason; Chang, Yia Chung

    2008-01-01

    Dot-in-well (DWELL) quantum-dot infrared photodetectors (QDIPs) [DWELL-QDIPs] are subjects of research as potentially superior alternatives to prior QDIPs. Heretofore, there has not existed a reliable method for fabricating quantum dots (QDs) having precise, repeatable dimensions. This lack has constituted an obstacle to the development of uniform, high-performance, wavelength-tailorable QDIPs and of focal-plane arrays (FPAs) of such QDIPs. However, techniques for fabricating quantum-well infrared photodetectors (QWIPs) having multiple-quantum- well (MQW) structures are now well established. In the present research on DWELL-QDIPs, the arts of fabrication of QDs and QWIPs are combined with a view toward overcoming the deficiencies of prior QDIPs. The longer-term goal is to develop focal-plane arrays of radiationhard, highly uniform arrays of QDIPs that would exhibit high performance at wavelengths from 8 to 15 m when operated at temperatures between 150 and 200 K. Increasing quantum efficiency is the key to the development of competitive QDIP-based FPAs. Quantum efficiency can be increased by increasing the density of QDs and by enhancing infrared absorption in QD-containing material. QDIPs demonstrated thus far have consisted, variously, of InAs islands on GaAs or InAs islands in InGaAs/GaAs wells. These QDIPs have exhibited low quantum efficiencies because the numbers of QD layers (and, hence, the areal densities of QDs) have been small typically five layers in each QDIP. The number of QD layers in such a device must be thus limited to prevent the aggregation of strain in the InAs/InGaAs/GaAs non-lattice- matched material system. The approach being followed in the DWELL-QDIP research is to embed In- GaAs QDs in GaAs/AlGaAs multi-quantum- well (MQW) structures (see figure). This material system can accommodate a large number of QD layers without excessive lattice-mismatch strain and the associated degradation of photodetection properties. Hence, this material

  9. Brightness-equalized quantum dots

    Science.gov (United States)

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-10-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  10. Synthesis and applications of carbon dots

    OpenAIRE

    Nolan, Andrew Steven

    2015-01-01

    The use of non-invasive methods to visualise and monitor processes inside living organisms is vital in the understanding and diagnosis of disease. The work in this thesis details the synthesis and applications of a new imaging modality; carbon dots, whose inherent fluorescence and non-toxic nature makes them attractive alternatives to more traditional ‘quantum dots’. In this thesis, different methods of carbon dot synthesis were attempted in order to produce carbon dots of t...

  11. Colloidal quantum dots: synthesis, properties and applications

    Science.gov (United States)

    Brichkin, S. B.; Razumov, V. F.

    2016-12-01

    Key recent results obtained in studies of a new class of luminophores, colloidal quantum dots, are analyzed. Modern methods for the synthesis and post-synthetic treatment of colloidal quantum dots that make it possible to achieve record high quantum yield of luminescence and to modify their characteristics for specific applications are considered. Currently important avenues of research on colloidal quantum dots and the problems in and prospects for their practical applications in various fields are discussed. The bibliography includes 272 references.

  12. La economía social y solidaria como alternativa económica. Bienes comunes y democracia

    Directory of Open Access Journals (Sweden)

    Jaime Abad Montesinos

    2014-10-01

    Full Text Available Normal 0 21 MicrosoftInternetExplorer4 Resumen: El presente artículo trata de enmarcar la economía social y solidaria en el seno del actual debate producto de la crisis económica vigente, haciendo especial hincapié en las cuestiones relacionadas con los bienes comunes y la gestión democrática. La crisis presente ha puesto de manifiesto la necesidad de proponer modelos socio-económicos alternativos que aúnen democracia, compromiso social y sostenibilidad del medio ambiente. La economía social y solidaria, sin ser un programa homogéneo, está contribuyendo a proponer respuestas a algunos de los problemas actuales en materia de desempleo e integración social, revalorizando en los procesos económicos, no sólo los intercambios mercantiles, sino también los intereses sociales y los recursos naturales. Abstract:This article aims to enlighten the importance ofsolidary and social economy in the present discussion, whose importance has increased as a result of the current economic crisis, making a special emphasis on subjects such as commons goods and democratic management. The crisis has brought up the need for alternative socio-economical management models which must combine democracy, social commitment and environmental sustainability. Solidary and social economy, without being a homogeneous program, are proposing answers to some of the present problems related to unemployment and social integration, contributing to increase the value of economic processes, not only in commercial exchanges, but also the social interest and natural resources. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} /* Style Definitions */ table.MsoNormalTable {mso

  13. Thermoelectric energy harvesting with quantum dots.

    Science.gov (United States)

    Sothmann, Björn; Sánchez, Rafael; Jordan, Andrew N

    2015-01-21

    We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn toward quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.

  14. Activation of silicon quantum dots for emission

    Institute of Scientific and Technical Information of China (English)

    Huang Wei-Qi; Miao Xin-Jian; Huang Zhong-Mei; Liu Shi-Rong; Qin Chao-Jian

    2012-01-01

    The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs.From this point of view,we can build up radiative matter for emission.Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots.Our experimental results demonstrate that annealing is important in the treatment of the activation,and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots.

  15. Synthetic Developments of Nontoxic Quantum Dots.

    Science.gov (United States)

    Das, Adita; Snee, Preston T

    2016-03-03

    Semiconductor nanocrystals, or quantum dots (QDs), are candidates for biological sensing, photovoltaics, and catalysis due to their unique photophysical properties. The most studied QDs are composed of heavy metals like cadmium and lead. However, this engenders concerns over heavy metal toxicity. To address this issue, numerous studies have explored the development of nontoxic (or more accurately less toxic) quantum dots. In this Review, we select three major classes of nontoxic quantum dots composed of carbon, silicon and Group I-III-VI elements and discuss the myriad of synthetic strategies and surface modification methods to synthesize quantum dots composed of these material systems.

  16. POLARON IN CYLINDRICAL AND SPHERICAL QUANTUM DOTS

    Directory of Open Access Journals (Sweden)

    L.C.Fai

    2004-01-01

    Full Text Available Polaron states in cylindrical and spherical quantum dots with parabolic confinement potentials are investigated applying the Feynman variational principle. It is observed that for both kinds of quantum dots the polaron energy and mass increase with the increase of Frohlich electron-phonon coupling constant and confinement frequency. In the case of a spherical quantum dot, the polaron energy for the strong coupling is found to be greater than that of a cylindrical quantum dot. The energy and mass are found to be monotonically increasing functions of the coupling constant and the confinement frequency.

  17. Random Feature Maps for Dot Product Kernels

    CERN Document Server

    Kar, Purushottam

    2012-01-01

    Approximating non-linear kernels using feature maps has gained a lot of interest in recent years due to applications in reducing training and testing times of SVM classifiers and other kernel based learning algorithms. We extend this line of work and present low distortion embeddings for dot product kernels into linear Euclidean spaces. We base our results on a classical result in harmonic analysis characterizing all dot product kernels and use it to define randomized feature maps into explicit low dimensional Euclidean spaces in which the native dot product provides an approximation to the dot product kernel with high confidence.

  18. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

    2002-01-01

    -power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

  19. Dissipative tunneling in structures with quantum dots and quantum molecules

    OpenAIRE

    Dahnovsky, Yu. I.; Krevchik, V. D.; Semenov, M. B.; Yamamoto, K.; Zhukovsky, V. Ch.; Aringazin, A. K.; Kudryashov, E. I.; Mayorov, V. G.

    2005-01-01

    The problem of tunneling control in systems "quantum dot - quantum well" (as well as "quantum dot - quantum dot" or quantum molecule) and "quantum dot - bulk contact" is studied as a quantum tunneling with dissipation process in the semiclassical (instanton) approximation. For these systems temperature and correlation between a quantum dot radius and a quantum well width (or another quantum dot radius) are considered to be control parameters. The condition for a single electron blockade is fo...

  20. Negros y pardos propietarios de bienes raíces y de esclavos en el Buenos Aires de fines del período hispánico

    Directory of Open Access Journals (Sweden)

    Rosal, Miguel A.

    2001-12-01

    Full Text Available El trabajo pretende ilustrar un aspecto poco conocido dentro de la problemática afroporteña; nos referimos a la capacidad para adquirir bienes inmuebles —terrenos y casas— y esclavos que tenían los integrantes de la raza africana, en general de condición libre, pero también esclavizados, en el Buenos Aires tardocolonial, capacidad fundada sin duda en una significativa actividad laboral y, en especial, artesanal. En ese sentido, hacemos referencia a las características de los inmuebles, a los precios de los mismos, a su ubicación en el espacio urbano (distribución de los afroporteños según los barrios y, por último, a la participación de negros y blancos en el mercado porteño de compraventa de bienes raíces y de esclavos.

  1. “Jeneros de gusto y sobretodos ingleses”: el impacto cultural del consumo de bienes ingleses por la clase alta bogotana .

    Directory of Open Access Journals (Sweden)

    Ana Maria Otero Cleves.

    2009-05-01

    Full Text Available Este artículo analiza el impacto cultural del consumo de bienes Inglés por la clase alta de Bogotá durante el siglo XIX. Se sugiere que el consumo de productos Inglés después de la independencia del país fue uno de los principales mecanismos empleados por las clases altas para asegurar su posición social, así como para construir una nación moderna, de acuerdo a las normas europeas. Por lo tanto, el artículo analiza el papel que el consumo de bienes extranjeros en el proceso de construcción de la nación y la diferenciación social en el siglo XIX.

  2. Hacia una economía más humana: Tecnología en bienes vitales para reducir el costo de vida

    Directory of Open Access Journals (Sweden)

    Guillermo Runciman Saettone

    2014-11-01

    Full Text Available El presente estudio representa un ensayo que tiene como objetivo proponer lineamientos aplicables a la economía peruana para incrementar la productividad en la elaboración de los bienes vitales (agua segura, alimentos nutritivos, abrigo y techo y los servicios asociados a ellos. A juicio de los autores, estos son los bienes indispensables para emprender cualquier proyecto de vida del ser humano. En la aplicación, se presentan ejemplos de proyectos que permitirían lograr el objetivo en el Perú. Para ello, se toman en consideración aspectos geográficos determinantes; el desarrollo de la infraestructura de energía, transporte y sistemas hídricos; y la propuesta de un plan de desarrollo a nivel macroregional.

  3. Prolegómenos al vivir bien-buen vivir: una evaluación normativa y práctica

    Directory of Open Access Journals (Sweden)

    Edwin Cruz Rodríguez

    2015-06-01

    Full Text Available Este trabajo examina el concepto de vivir bien-buen vivir ponderando sus contribuciones y limitaciones. Esta cosmovisión tiene un horizonte normativo más ambicioso que el paradigma del desarrollo, pues apuesta por una concepción de la pobreza y la riqueza que no se reduce a la acumulación de bienes materiales, una economía que comprende sus efectos sobre la naturaleza y se centra en la satisfacción de necesidades, y una descolonización de los saberes. No obstante, se caracteriza por un déficit de operacionalización que se manifiesta en la dificultad para definir políticas concretas e indicadores de medición precisos.

  4. Palpitando la modernidad: el negocio de bienes raíces en Cali (Colombia a partir del caso de Jorge Garcés Borrero, 1900-1944

    Directory of Open Access Journals (Sweden)

    María Fernanda Erazo Obando

    2014-01-01

    Full Text Available El objetivo del presente artículo es analizar el movimiento de compra y venta de bienes raíces en Cali (Colombia durante la primera mitad del siglo XX. Para ello, se toma como referencia la empresa del comerciante Jorge Garcés Borrero, la cual, se enfocó principalmente en la ejecución de este tipo de negocios. Dicha empresa, a pesar de no haberse constituido legal y jurídicamente, presentó las características de una compañía como tal, generando importantes inversiones y ganancias a partir del mercado de bienes. Apoyados en fuentes notariales se explica el desarrollo de esta actividad comercial entre 1900-1944.

  5. Palpitando la modernidad: el negocio de bienes raíces en Cali (Colombia a partir del caso de Jorge Garcés Borrero, 1900-1944

    Directory of Open Access Journals (Sweden)

    María Fernanda Erazo Obando

    2014-07-01

    Full Text Available El objetivo del presente artículo es analizar el movimiento de compra y venta de bienes raíces en Cali (Colombia durante la primera mitad del siglo XX. Para ello, se toma como referencia la empresa del comerciante Jorge Garcés Borrero, la cual, se enfocó principalmente en la ejecución de este tipo de negocios. Dicha empresa, a pesar de no haberse constituido legal y jurídicamente, presentó las características de una compañía como tal, generando importantes inversiones y ganancias a partir del mercado de bienes. Apoyados en fuentes notariales se explica el desarrollo de esta actividad comercial entre 1900-1944.

  6. Fuentes de información para el diseño de un Sistema de Vigilancia e Inteligencia en el Registro Provincial de Bienes Culturales de Matanzas

    Directory of Open Access Journals (Sweden)

    Justa Bielka Cantillo González

    2007-01-01

    Full Text Available Por la importancia que reviste la conservación del Patrimonio Cultural, se identifican, con la utilización de herramientas estadísticas (Coeficiente de Concordancia de Kendall las fuentes de información relevantes, para el posterior diseño de un Sistema de Vigilancia e Inteligencia en el Registro Provincial de Bienes Culturales de la provincia de Matanzas

  7. Quantum Dot Spectrum Converters for Enhanced High Efficiency Photovoltaics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This research proposes to enhance solar cell efficiency, radiation resistance and affordability. The Quantum Dot Spectrum Converter (QDSC) disperses quantum dots...

  8. La América Latina y El Caribe en 1913 y 1925. Enfoque desde las importaciones de bienes de capital

    Directory of Open Access Journals (Sweden)

    Xavier Tafunell

    2008-01-01

    Full Text Available En este artículo estudiamos el desarrollo económico alcanzado por la totalidad de los Estados latinoamericanos y caribeños soberanos en 1913 y 1925 desde una perspectiva inédita en el estudio del conjunto de la región: las importaciones y la producción –que sumadas equivalen al consumo aparente– de bienes de capital. Asegurada la fiabilidad de las estadísticas del comercio exterior, procedemos a reconstruir las magnitudes de los bienes de capital adquiridos por las 20 repúblicas. También estimamos la producción interna. La nueva evidencia empírica pone de manifiesto las enormes diferencias existentes en el seno de la región en el consumo per cápita de bienes de capital al término de la primera oleada globalizadora. La comparación entre los niveles de 1913 y 1925 revela que, en general, la contienda mundial no favoreció el proceso de sustitución de importaciones de la región, pero no en todos los países por igual.

  9. El dominio público y los bienes públicos: Europa y América Latina. ¿El hijo sigue mirando al padre?

    Directory of Open Access Journals (Sweden)

    Sergio Chemás

    2015-12-01

    Full Text Available El estudio del derecho de los bienes públicos en América Latina y en Colombia es algo todavía poco desarrollado. Se sigue mirando hacia el derecho comparado para obtener respuestas, tal como un hijo mira a su padre, porque fue allá donde surgieron los grandes desarrollos del tema. El dominio público en Europa y América Latina es producto de un encuentro entre varias autoridades en el tema de los bienes públicos tanto de Europa como de América Latina. Esta reseña se divide en tres partes: i un breve análisis de derecho comparado frente al concepto de dominio público; ii la identificación de los contenidos más interesantes e innovadores de los regímenes de bienes públicos, y iii un ejercicio académico para que el lector lo desarrolle al leer el libro.

  10. Nitrogen-Doped Carbon Dots for "green" Quantum Dot Solar Cells.

    Science.gov (United States)

    Wang, Hao; Sun, Pengfei; Cong, Shan; Wu, Jiang; Gao, Lijun; Wang, Yun; Dai, Xiao; Yi, Qinghua; Zou, Guifu

    2016-12-01

    Considering the environment protection, "green" materials are increasingly explored for photovoltaics. Here, we developed a kind of quantum dots solar cell based on nitrogen-doped carbon dots. The nitrogen-doped carbon dots were prepared by direct pyrolysis of citric acid and ammonia. The nitrogen-doped carbon dots' excitonic absorption depends on the N-doping content in the carbon dots. The N-doping can be readily modified by the mass ratio of reactants. The constructed "green" nitrogen-doped carbon dots solar cell achieves the best power conversion efficiency of 0.79 % under AM 1.5 G one full sun illumination, which is the highest efficiency for carbon dot-based solar cells.

  11. Thick-shell nanocrystal quantum dots

    Science.gov (United States)

    Hollingsworth, Jennifer A.; Chen, Yongfen; Klimov, Victor I.; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  12. Optically active quantum-dot molecules.

    Science.gov (United States)

    Shlykov, Alexander I; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V; Rukhlenko, Ivan D

    2017-02-20

    Chiral molecules made of coupled achiral semiconductor nanocrystals, also known as quantum dots, show great promise for photonic applications owing to their prospective uses as configurable building blocks for optically active structures, materials, and devices. Here we present a simple model of optically active quantum-dot molecules, in which each of the quantum dots is assigned a dipole moment associated with the fundamental interband transition between the size-quantized states of its confined charge carriers. This model is used to analytically calculate the rotatory strengths of optical transitions occurring upon the excitation of chiral dimers, trimers, and tetramers of general configurations. The rotatory strengths of such quantum-dot molecules are found to exceed the typical rotatory strengths of chiral molecules by five to six orders of magnitude. We also study how the optical activity of quantum-dot molecules shows up in their circular dichroism spectra when the energy gap between the molecular states is much smaller than the states' lifetime, and maximize the strengths of the circular dichroism peaks by optimizing orientations of the quantum dots in the molecules. Our analytical results provide clear design guidelines for quantum-dot molecules and can prove useful in engineering optically active quantum-dot supercrystals and photonic devices.

  13. Research on Self-Assembling Quantum Dots.

    Science.gov (United States)

    1995-10-30

    0K. in a second phase of this contract we turned our efforts to the fabrication and studies of self assembled quantum dots . We first demonstrated a...method for producing InAs-GasAs self assembled quantum dots (SAD) using MBE. (AN)

  14. Double Acceptor Interaction in Semimagnetic Quantum Dot

    Directory of Open Access Journals (Sweden)

    A. Merwyn Jasper D. Reuben

    2011-01-01

    Full Text Available The effect of geometry of the semimagnetic Quantum Dot on the Interaction energy of a double acceptor is computed in the effective mass approximation using the variational principle. A peak is observed at the lower dot sizes as a magnetic field is increased which is attributed to the reduction in confinement.

  15. Quantum Dots Coupled to a Superconductor

    DEFF Research Database (Denmark)

    Jellinggaard, Anders Robert

    are tuned electrostatically. This includes tuning the odd occupation of the dot through a quantum phase transition, where it forms a singlet with excitations in the superconductor. We detail the fabrication of these bottom gated devices, which additionally feature ancillary sensor dots connected...

  16. Detecting the chirality for coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Cao Huijuan [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China); Hu Lian [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: huliancaohj@yahoo.com

    2008-04-21

    We propose a scheme to detect the chirality for a system consisting of three coupled quantum dots. The chirality is found to be determined by the frequency of the transition between chiral states under the chiral symmetry broken perturbation. The results are important to construct quantum gates and to demonstrate chiral entangle states in the triangle spin dots.

  17. Optical anisotropy in vertically coupled quantum dots

    DEFF Research Database (Denmark)

    Yu, Ping; Langbein, Wolfgang Werner; Leosson, Kristjan;

    1999-01-01

    We have studied the polarization of surface and edge-emitted photoluminescence (PL) from structures with vertically coupled In0.5Ga0.5As/GaAs quantum dots (QD's) grown by molecular beam epitaxy. The PL polarization is found to be strongly dependent on the number of stacked layers. While single...... number due to increasing dot size....

  18. Optical studies of capped quantum dots

    NARCIS (Netherlands)

    Wuister, S.F.

    2005-01-01

    This thesis describes the synthesis and spectroscopy of CdSe and CdTe semiconductor quantum dots (QDs). The first chapter gives an introduction into the unique size dependent properties of semiconductor quantum dots. Highly luminescent QDs of CdSe and CdTe were prepared via a high temperature method

  19. Optical Properties of Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Perinetti, U.

    2011-01-01

    This thesis presents different optical experiments performed on semiconductor quantum dots. These structures allow to confine a small number of electrons and holes to a tiny region of space, some nm across. The aim of this work was to study the basic properties of different types of quantum dots mad

  20. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  1. Biocompatible quantum dots for biological applications.

    Science.gov (United States)

    Rosenthal, Sandra J; Chang, Jerry C; Kovtun, Oleg; McBride, James R; Tomlinson, Ian D

    2011-01-28

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots.

  2. Quantum-dot supercrystals for future nanophotonics

    Science.gov (United States)

    Baimuratov, Anvar S.; Rukhlenko, Ivan D.; Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.

    2013-01-01

    The study of supercrystals made of periodically arranged semiconductor quantum dots is essential for the advancement of emerging nanophotonics technologies. By combining the strong spatial confinement of elementary excitations inside quantum dots and exceptional design flexibility, quantum-dot supercrystals provide broad opportunities for engineering desired optical responses and developing superior light manipulation techniques on the nanoscale. Here we suggest tailoring the energy spectrum and wave functions of the supercrystals' collective excitations through the variation of different structural and material parameters. In particular, by calculating the excitonic spectra of quantum dots assembled in two-dimensional Bravais lattices we demonstrate a wide variety of spectrum transformation scenarios upon alterations in the quantum dot arrangement. This feature offers unprecedented control over the supercrystal's electromagnetic properties and enables the development of new nanophotonics materials and devices.

  3. Blood Compatibility Evaluations of Fluorescent Carbon Dots.

    Science.gov (United States)

    Li, Sha; Guo, Zhong; Zhang, Yi; Xue, Wei; Liu, Zonghua

    2015-09-02

    Because of their unique advantages, fluorescent carbon dots are gaining popularity in various biomedical applications. For these applications, good biosafety is a prerequisite for their use in vivo. Studies have reported the preliminary biocompatibility evaluations of fluorescent carbon dots (mainly cytotoxicity); however, to date, little information is available about their hemocompatibility, which could impede their development from laboratory to bedside. In this work, we evaluated the hemocompatibility of fluorescent carbon dots, which we prepared by hydrothermal carbonization of α-cyclodextrin. The effects of the carbon dots on the structure and function of key blood components were investigated at cellular and molecular levels. In particular, we considered the morphology and lysis of human red blood cells, the structure and conformation of the plasma protein fibrinogen, the complement activation, platelet activation, and in vitro and in vivo blood coagulation. We found that the carbon dots have obvious concentration-dependent effects on the blood components. Overall, concentrations of the fluorescent carbon dots at ≤0.1 mg/mL had few adverse effects on the blood components, but at higher doses, the carbon dots impair the structure and function of the blood components, causing morphological disruptions and lysis of red blood cells, interference in the local microenvironments of fibrinogen, activation of the complement system, and disturbances in the plasma and whole blood coagulation function in vitro. However, the carbon dots tend to activate platelets only at low concentrations. Intravenous administration of the carbon dots at doses up to 50 mg/kg did not impair the blood coagulation function. These results provide valuable information for the clinical application of fluorescent carbon dots.

  4. Peptide dot immunoassay and immunoblotting: electroblotting from aluminum thin-layer chromatography plates and isoelectric focusing gels to activated nitrocellulose

    DEFF Research Database (Denmark)

    Bjerrum, O.J.; Holm, A.; Lauritzen, Edgar;

    1993-01-01

    Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins......Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins...

  5. Electron transport in quantum dots

    CERN Document Server

    2003-01-01

    When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the...

  6. Chiral quantum dot based materials

    Science.gov (United States)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii

    2014-05-01

    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  7. Quantum dots with single-atom precision.

    Science.gov (United States)

    Fölsch, Stefan; Martínez-Blanco, Jesús; Yang, Jianshu; Kanisawa, Kiyoshi; Erwin, Steven C

    2014-07-01

    Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.

  8. Avances y perspectivas del derecho para la restitución de bienes culturales a sus países de origen: el caso del patrimonio cultural quimbaya

    OpenAIRE

    Rengifo Lozano, Antonio José

    2013-01-01

    Con base en el estudio comparado de los casos de restitución de los Mármoles del Partenón, promovido por Grecia y del Patrimonio Cultural Quimbaya en Colombia, el presente artículo sustenta la tesis de que aunque el derecho para la restitución de bienes culturales se encuentra en etapa inicial de consolidación y, por tanto, de seguro tendrá muchos desarrollos en el futuro, existen en la actualidad bases jurídicas suficientes para hacer efectiva esa restitución, necesaria para realizar el l...

  9. La prescripción de bienes inmuebles y la garantía de los derechos patrimoniales de las personas

    OpenAIRE

    Salguero Real, Mayra Semira

    2012-01-01

    La presente tesis intitulada “La Prescripción de Bienes Inmuebles y la Garantía de los Derechos Patrimoniales de las Personas” se realiza como requisito previo a la obtención del título de Magister en Derecho Civil y Procesal Civil, desarrollada en cuatro capítulos, cuyo contenido se detalla a continuación. En el Capítulo I, aborda el problema que da lugar a esta investigación, esto es, la ausencia de procedimiento para la ejecución de los títulos escriturarios por la vía Ordinaria medi...

  10. Sobre los saberes culturales y el fenómeno "sentirse bien-sentirse mal" On cultural knowledge and the phenomenon "feel good-fell bad"

    Directory of Open Access Journals (Sweden)

    Virtudes Rodero Sánchez

    2010-09-01

    Full Text Available El objetivo del presente estudio es identificar los saberes culturales inmersos en el fenómeno "sentirse-bien, sentirse mal", en diferentes situaciones de cuidado. Se elaboró un estudio cualitativo con un enfoque fenomenológico interpretativo, mediante el análisis de 18 narrativas a partir de entrevistas en profundidad realizadas por alumnas del Máster en Ciencias de la Enfermería en diferentes contextos de cuidados. Las categorías identificadas fueron: (1 Cronicidad y concepto de sentirse bien-sentirse mal. En la cronicidad este concepto está íntimamente relacionado con la recuperación de las actividades de la vida diaria y es componente importante en la percepción individual del concepto "calidad de vida". (2 Momentos agudos de enfermedad y concepto de sentirse bien-sentirse mal. En el análisis de los relatos del paciente aparecieron aspectos esenciales del fenómeno "sentirse bien-sentirse mal" para aumentar la comprensión de aspectos universales de algunos de sus componentes. Destacar que el fenómeno está íntimamente relacionado con la recuperación de las actividades de la vida diaria, y es un mediador importante en la percepción individual del concepto "calidad de vida". El interés de cara al cuidado es distinguir sus componentes universales, contextualizarlos en la práctica, dentro de las singularidades que presenta cada persona, de modo que nos permita su potenciación. El resultado es un cambio en la experiencia sentida.The object of the present study is to identify cultural knowledges immersed in the feeling-well, feeling-bad phenomenon in different care settings. A qualitative study was undertaken using a phenomenological interpretation approach through a meta-analysis of 18 narratives of profound interviews undertaken by Nursing Science Master Degree Students in different care situations. The categories established were: (1 Chronicity and the concept of feeling well-feeling bad. In this category, this concept is

  11. Aguas dulces y derecho internacional : el agua como bien común y como derecho humano desde la perspectiva del desarrollo sostenible

    OpenAIRE

    2014-01-01

    Este trabajo tiene por objeto el análisis del régimen internacional de las aguas dulces como bien común y como derecho humano, desde una perspectiva del desarrollo sostenible. El análisis separado del régimen internacional de las aguas dulces compartidas y el régimen internacional del derecho humano al agua y al saneamiento nos permite detectar un cambio de paradigma en la regulación de la materia que puede apuntar una progresiva priorización de la garantía del DHAS y la gestió...

  12. El objeto de protección del derecho penal y el bien jurídico tutelado por el derecho penal en el estado social de derecho

    OpenAIRE

    2014-01-01

    El resumen es una presentación abreviada y precisa (la NTC 1486 de 2008 recomienda El presente texto, tiene como finalidad reconstruir la línea del pensamiento jurídico penal en torno al objeto de protección y la relación que este concepto guarda con el bien jurídico tutelado. Esta reconstrucción nos permitirá demostrar la inviabilidad de la teoría funcionalista de Gunter Jakobs frente al objeto de protección en un Estado Social de Derecho, democrático, participativo y pluralista, fundando en...

  13. LA LEY 4/2012, DE 6 DE JULIO, DE APROVECHAMIENTO POR TURNO DE BIENES DE USOS TURÍSTICOS: ¿NUEVO PRODUCTO TURÍSTICO?

    Directory of Open Access Journals (Sweden)

    Francisca Ramón Fernández

    2014-07-01

    Full Text Available Los productos turísticos adaptados a las TICs y a la combinación entre propiedad y arrendamiento ha sido objeto de legislación desde 1998. La mal denominada multipropiedad, también conocida como aprovechamiento por turno de bienes de usos turístico ha sido regulada recientemente, junto con otros contratos como los productos vacacionales de larga duración. En este trabajo exponemos su consideración como producto, así como los cambios introducidos en la Ley 4/2012, de 6 de julio, y su apertura al ámbito del turismo activo.

  14. ENTRE EL HUMANISMO Y EL MERCANTILISMO: EL BIEN COMÚN EN EL ABASTO DE CARNE DE CIUDAD DE MÉXICO, 1708-1716

    OpenAIRE

    Quiroz,Enriqueta

    2011-01-01

    En este artículo se analizan las prácticas políticas ejercidas por miembros del gobierno local en la ciudad de México a principios del siglo XVIII, en torno al abasto de carne. La idea es observar la búsqueda del bien común, pero asentado no solo en bases humanistas, sino también dentro de una política mercantilista, en la que los intereses económicos de la Corona pretenden confluir como en un solo cuerpo con los de sus súbditos.

  15. Scanning gate microscopy of ultra clean carbon nanotube quantum dots

    OpenAIRE

    Xue, Jiamin; Dhall, Rohan; Cronin, Stephen B.; LeRoy, Brian J.

    2015-01-01

    We perform scanning gate microscopy on individual suspended carbon nanotube quantum dots. The size and position of the quantum dots can be visually identified from the concentric high conductance rings. For the ultra clean devices used in this study, two new effects are clearly identified. Electrostatic screening creates non-overlapping multiple sets of Coulomb rings from a single quantum dot. In double quantum dots, by changing the tip voltage, the interactions between the quantum dots can b...

  16. Time-bin Entanglement from Quantum Dots

    CERN Document Server

    Weihs, Gregor; Predojević, Ana

    2016-01-01

    The desire to have a source of single entangled photon pairs can be satisfied using single quantum dots as emitters. However, we are not bound to pursue only polarization entanglement, but can also exploit other degrees of freedom. In this chapter we focus on the time degree of freedom, to achieve so-called time-bin entanglement. This requires that we prepare the quantum dot coherently into the biexciton state and also build special interferometers for analysis. Finally this technique can be extended to achieve time-bin and polarization hyper-entanglement from a suitable quantum dot.

  17. Fluorescent Quantum Dots for Biological Labeling

    Science.gov (United States)

    McDonald, Gene; Nadeau, Jay; Nealson, Kenneth; Storrie-Lomardi, Michael; Bhartia, Rohit

    2003-01-01

    Fluorescent semiconductor quantum dots that can serve as "on/off" labels for bacteria and other living cells are undergoing development. The "on/off" characterization of these quantum dots refers to the fact that, when properly designed and manufactured, they do not fluoresce until and unless they come into contact with viable cells of biological species that one seeks to detect. In comparison with prior fluorescence-based means of detecting biological species, fluorescent quantum dots show promise for greater speed, less complexity, greater sensitivity, and greater selectivity for species of interest. There are numerous potential applications in medicine, environmental monitoring, and detection of bioterrorism.

  18. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    . The main property of semiconductor quantum dots compared to bulk material or even quantum well structures is the discrete nature of the allowed states, which means that inversion of the medium can be obtained for very low electron densities. This has led to the fabrication of quantum dot lasers with record......-low threshold currents and amplifiers with record-high power levels. In this tutorial we will review the basic properties of quantum dots, emphasizing the properties which are important for laser and amplifier applications, as well as devices for all-optical signal processing. The high-speed properties...

  19. Electronic properties of aperiodic quantum dot chains

    Science.gov (United States)

    Korotaev, P. Yu.; Vekilov, Yu. Kh.; Kaputkina, N. E.

    2012-04-01

    The electronic spectral and transport properties of aperiodic quantum dot chains are investigated. The systems with singular continuous energy spectrum are considered: Thue-Morse chain, double-periodic chain, Rudin-Shapiro chain. The influence of electronic energy in quantum dot on the spectral properties, band structure, density of states and spectral resistivity, is discussed. Low resistivity regions correspond to delocalized states and these states could be current states. Also we discuss the magnetic field application as the way to tune electronic energy in quantum dot and to obtain metallic or insulating conducting states of the systems.

  20. Amplification Without Inversion in Semiconductor Quantum Dot

    Science.gov (United States)

    Hajibadali, A.; Abbasian, K.; Rostami, A.

    In this paper, we have realized amplification without inversion (AWI) in quantum dot (QD). A Y-type four-level system of InxGa1-xN quantum dot has been obtained and investigated for AWI. It has been shown that, with proper setting of control fields' amplitude, we can obtain reasonable gain. With proper setting of phase difference of control fields and probe field, we can obtain considerable gain in resonant wavelength. We have designed this system by solving the Schrödinger-Poisson equations for InxGa1-xN quantum dot in GaN substrate, self-consistently.

  1. Quantum Dots Investigated for Solar Cells

    Science.gov (United States)

    Bailey, Sheila G.; Castro, Stephanie L.; Raffaelle, Ryne P.; Hepp, Aloysius F.

    2001-01-01

    The NASA Glenn Research Center has been investigating the synthesis of quantum dots of CdSe and CuInS2 for use in intermediate-bandgap solar cells. Using quantum dots in a solar cell to create an intermediate band will allow the harvesting of a much larger portion of the available solar spectrum. Theoretical studies predict a potential efficiency of 63.2 percent, which is approximately a factor of 2 better than any state-of-the-art devices available today. This technology is also applicable to thin-film devices--where it offers a potential four-fold increase in power-to-weight ratio over the state of the art. Intermediate-bandgap solar cells require that quantum dots be sandwiched in an intrinsic region between the photovoltaic solar cell's ordinary p- and n-type regions (see the preceding figure). The quantum dots form the intermediate band of discrete states that allow sub-bandgap energies to be absorbed. However, when the current is extracted, it is limited by the bandgap, not the individual photon energies. The energy states of the quantum dot can be controlled by controlling the size of the dot. Ironically, the ground-state energy levels are inversely proportional to the size of the quantum dots. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Ba Wendi et al., in the early 1990's. The most studied quantum dots prepared by this method have been of CdSe. To produce these dots, researchers inject a syringe of the desired organometallic precursors into heated triocytlphosphine oxide (TOPO) that has been vigorously stirred under an inert atmosphere (see the following figure). The solution immediately begins to change from colorless to yellow, then orange and red/brown, as the quantum dots increase in size. When the desired size is reached, the heat is removed from the flask. Quantum dots of different sizes can be identified by placing them under a "black light" and observing the various color differences in

  2. Quantum dot heterojunction solar cells: the mechanism of device operation and impacts of quantum dot oxidation

    OpenAIRE

    Ihly, Rachelle

    2014-01-01

    This thesis explores the understanding of the chemistry and physics of colloidal quantum dots for practical solar energy photoconversion. Solar cell devices that make use of PbS quantum dots generally rely on constant and unchanged optical properties such that band gap energies remain tuned within the device. The design and development of unique experiments to ascertain mechanisms of optical band gap shifts occurring in PbS quantum dot thin-films exposed to air are discussed. The systematic s...

  3. La protección del “paisaje sonoro”: Los toques manuales de campanas y su declaración como Bien de Interés Cultural

    Directory of Open Access Journals (Sweden)

    Francisca Ramón Fernández

    2014-06-01

    Full Text Available En el presente trabajo analizamos la protección de los toques manuales de campanas y su declaración como Bien de Interés Cultural Inmaterial por parte de la legislación de patrimonio cultural valenciano. A través de la evolución histórica del bien podemos observar las razones de su protección y nos ha llevado a cuestionarnos si ha sido adecuado su consideración como paisaje sonoro, concepto muy alejado en el ámbito jurídico y que no es compartido plenamente. Siendo la primera vez que se protege este bien, resulta especialmente interesante la ampliación de la protección a los denominados elementos que forman parte del bien, como es el caso de las partituras.

  4. Tailoring Magnetism in Quantum Dots

    Science.gov (United States)

    Zutic, Igor; Abolfath, Ramin; Hawrylak, Pawel

    2007-03-01

    We study magnetism in magnetically doped quantum dots as a function of particle numbers, temperature, confining potential, and the strength of Coulomb interaction screening. We show that magnetism can be tailored by controlling the electron-electron Coulomb interaction, even without changing the number of particles. The interplay of strong Coulomb interactions and quantum confinement leads to enhanced inhomogeneous magnetization which persists at substantially higher temperatures than in the non-interacting case or in the bulk-like dilute magnetic semiconductors. We predict a series of electronic spin transitions which arise from the competition between the many-body gap and magnetic thermal fluctuations. Cond-mat/0612489. [1] R. Abolfath, P. Hawrylak, I. Zuti'c, preprint.

  5. Bienes y servicios ecosistémicos en la planificación y gestión de áreas urbanas consolidadas

    Directory of Open Access Journals (Sweden)

    Rafael Francesconi Latorre

    2014-06-01

    Full Text Available En el contexto de una planificación que declara privilegiar los elementos de la estructura ecológica, pero que podría comprometer la provisión de suelos para soportar coberturas que ofrezcan bienes y servicios ecosistémicos, se presenta un aporte a la discusión sobre cómo lograr un balance entre densificación y provisión de estos bienes y servicios, mediante la reconstrucción de la transformación de la cobertura de un segmento de la cuenca del río Fucha en Bogotá en un lapso de 77 años y la verificación de las relaciones de dicha transformación con los instrumentos de planificación y gestión. Los resultados obtenidos sugieren una regulación reactiva, con limitaciones para conducir la ocupación del territorio, de la que se puede esperar una acentuación de la aridez. Estos resultados sustentan las conclusiones sobre la necesidad de replantear la regulación sobre áreas consolidadas e introducir instrumentos de gestión de la cobertura.

  6. Gasto particularista en bienes públicos locales: índice de desviación Particularistic expenditure on local public goods: an index of deviation

    Directory of Open Access Journals (Sweden)

    María Alejandra Armesto

    2012-09-01

    Full Text Available El gasto particularista del gobierno se opone al gasto programático. Los dos tipos de medidas clasifican los beneficios de políticas como particularistas si son bienes exclusivos o si son explicados por variables políticas. Este artículo desarrolla un índice de gasto particularista en bienes públicos locales medido como desviación con respecto al programa. Se aplica el índice a la oferta de servicios básicos por administraciones subnacionales seleccionadas en México y Argentina. Se muestra que el índice corre menos riesgos de sobreestimar o subestimar el gasto particularista y el gasto programático que las medidas existentes.This article compares particularistic and programmed government spending. The two types of measures classify the benefits of policies as particularistic if they are exclusive goods or if they are determined by political variables. This article contains an index of particularistic expenditure on local public goods, measured as a deviation from the program. It applies this index to the supply of basic services from selected sub-national administrations in Mexico and Argentina. It shows that this index is less likely to over- or under-estimate particularistic and programmatic expenditure than existing measures.

  7. Retos para el desarrollo de una economía no convencional y perspectivas sobre la valoración de bienes ambientales

    Directory of Open Access Journals (Sweden)

    Alexander Martínez R.

    2010-12-01

    Full Text Available La teoría económica se ha dividido claramente en dos grandes narrativas: la economía convencional y la economía no convencional. La primera no solo se caracteriza por su arsenal matemático, sino también por su alta carga ideológica en la perspectiva del liberalismo económico. La segunda es una teoría en construcción, con sendos avances metodológicos y estudios de campo, pero aún se encuentra profundamente cuestionada por la epistemología positivista. Este ensayo pretende abreviar los temas más críticos de aquellas dos teorías económicas, con especial énfasis en los instrumentos analíticos de la economía convencional para valorar bienes ambientales (economía ambiental, y mostrar resumidamente los supuestos teóricos y fortalezas de la economía no convencional (bioeconomía en materia de valoración de bienes ambientales. Finalmente, se propone un modelo de interpretación del mercado que reestructura la noción de Valor Económico Total de la economía ambiental, en una perspectiva bioeconómica.

  8. La casa y el ajuar de la familia Coronel a través de un inventario de bienes del siglo XVI

    Directory of Open Access Journals (Sweden)

    De la Peña Barroso, Efrén

    2015-12-01

    Full Text Available In the last years we have been working on the person of don Abraham Seneor/Fernán Pérez Coronel and his offspring, mainly from his son Íñigo López Coronel. In this occasion we will focus on the structure of the dwelling house and the household goods of the family through an inventory made in Segovia in 1522. This document will allow us to know the wealth level, the shy investment in luxury goods and the list of part of the household goods of this important family of Segovian conversos.Desde hace ya varios años estamos trabajando en la figura de don Abraham Seneor/Fernán Pérez Coronel y su descendencia, sobre todo por la vía de su hijo Íñigo López Coronel. En esta ocasión, estudiaremos la estructura espacial de su casa, sus bienes muebles y el ajuar de esta rama familiar a través de un inventario de bienes realizado en sus «casas principales» de la ciudad de Segovia en el año 1522. Este inventario nos permitirá acercarnos a los niveles de riqueza, a la escasa inversión en productos de lujo y al conocimiento de gran parte del ajuar de esta importante familia de judeoconversos segovianos.

  9. La repercusión del valor razonable de los bienes inmuebles en la utilidad de los estados financieros: una nota de investigación

    Directory of Open Access Journals (Sweden)

    Andrés Navarro Galera

    2009-01-01

    Full Text Available La elección en la reciente reforma contable española del criterio de valor razonable en lugar del coste histórico como base de valoración para determinados activos ha generado cierta controversia. Este trabajo estudia la posible incidencia de la adopción del valor razonable para el registro contable de los bienes inmuebles sobre la relevancia y la fiabilidad de la información financiera. El estudio empírico está basado en una encuesta sobre las percepciones de 151 responsables de la contabilidad de empresas españolas del sector de la construcción sobre la utilidad y fiabilidad de la información financiera basada en el valor razonable. El análisis de los resultados nos ha permitido concluir que, respecto al coste histórico, los responsables de contabilidad perciben que el valor razonable de los bienes inmuebles generaría estados financieros más útiles para representar la imagen fiel del patrimonio de la empresa. No obstante, los encuestados conciben la información financiera bajo valor razonable como menos objetiva y verificable. Asimismo, hemos comprobado que el tamaño de la empresa puede influir en la opinión de la repercusión del valor razonable sobre la relevancia y fiabilidad de los estados financieros.

  10. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...

  11. Ge Quantum Dot Infrared Imaging Camera Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna Innovations Incorporated proposes to develop a high performance Ge quantum dots-based infrared (IR) imaging camera on Si substrate. The high sensitivity, large...

  12. Algunas consideraciones sobre el bien jurídico tutelado en los delitos sobre la ordenación del territorio en el Nuevo Código Penal Español

    Directory of Open Access Journals (Sweden)

    Diego Silva Forné

    2015-09-01

    Full Text Available  La ciencia penal contemporánea considera ~n su amplia mayoría como misión del Derecho Penal, la tutela de bienes jurídicos; en particular, su protección se despliega frente a las agresiones más graves de que son éstos objeto, ya que también en los restantes sectores del ordenamiento jurídico cabe la salvaguarda de los mismos (...Contenido: Precisiones previas. Nociones sobre el concepto de bien jurídico.Breve sinopsis de su evolución. Planteos actuales. Concepciones de carácter formal. Concepciones materiales. Teorías de fundamento constitucional. Teorías de concepto sociológico. Funciones de bien jurídico. Los bienes jurídicos colectivos. El bien jurídicoprotegido en los delitos sobre la ordenación del territorio. Conceptos conexos. Discusión sobre el bien jurídico tutelado.Consideraciones político-criminales.

  13. Start Shift of Individual Quantum Dots

    Science.gov (United States)

    1999-06-18

    We will here describe the results of the influence of electric field on InP quantum dots embedded in GalnP, lattice matched to GaAs. Experimental...details The sample we used was grown by metal-organic vapour phase epitaxy, and contained InP quantum dots in GanP, lattice matched to GaAs (n-type

  14. Exciton in type-II quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Ortega, J; Escorcia, R A [Universidad del Magdalena, A. A. 731, Santa Marta (Colombia); Mikhailov, I D, E-mail: jsierraortega@gmail.co [Universidad Industrial de Santander, A. A. 678, Bucaramanga (Colombia)

    2009-05-01

    We study the quantum-size effect and the influence of the external magnetic field on the exciton ground state energy in the type-II InP quantum disk, lens and pyramid deposited on a wetting layer and embedded in a GaInP matrix. We show that the charge distribution over and below quantum dot and wetting layer induced by trapped exciton strongly depends on the quantum dot morphology and the strength of the magnetic field.

  15. Random Feature Maps for Dot Product Kernels

    OpenAIRE

    Kar, Purushottam; Karnick, Harish

    2012-01-01

    Approximating non-linear kernels using feature maps has gained a lot of interest in recent years due to applications in reducing training and testing times of SVM classifiers and other kernel based learning algorithms. We extend this line of work and present low distortion embeddings for dot product kernels into linear Euclidean spaces. We base our results on a classical result in harmonic analysis characterizing all dot product kernels and use it to define randomized feature maps into explic...

  16. Chaotic quantum dots with strongly correlated electrons

    OpenAIRE

    Shankar, R.

    2007-01-01

    Quantum dots pose a problem where one must confront three obstacles: randomness, interactions and finite size. Yet it is this confluence that allows one to make some theoretical advances by invoking three theoretical tools: Random Matrix theory (RMT), the Renormalization Group (RG) and the 1/N expansion. Here the reader is introduced to these techniques and shown how they may be combined to answer a set of questions pertaining to quantum dots

  17. Dot-dye-immunoassay for the diagnosis of schistosomiasis mansoni

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Teles Rabello

    1992-06-01

    Full Text Available A new serological assay dot-dye-immunoassay (dot-DIA was evaluated for the diagnosis of schistosomiasis mansoni. This method consist of four steps: (a biding of antigens to a nitrocellulose membrane (NC; (b blocking of free sites of the NC; (c incubation in specific primary antibody; (d detection of primary antibody reactivity by color development using second antibody coupled to textile dyes. Sera from 82 individuals, 61 with Schistosoma mansoni eggs in the stool and 21 stool negative were tested by ELISA, dot-ELISA, and dotDIA. A high level of agreement between the methods tested was observed for all sera tested: ELISA x dot-ELISA: 95.1%, ELISA x dot-DIA: 92.7% and dot-ELISA x dot-DIA: 97.6%. In this study, dot-DIA proved to be a feasible, sensitive, rapid and practical test for the diagnosis of shcistosomiasis.

  18. Quantum-dot-in-perovskite solids

    KAUST Repository

    Ning, Zhijun

    2015-07-15

    © 2015 Macmillan Publishers Limited. All rights reserved. Heteroepitaxy - atomically aligned growth of a crystalline film atop a different crystalline substrate - is the basis of electrically driven lasers, multijunction solar cells, and blue-light-emitting diodes. Crystalline coherence is preserved even when atomic identity is modulated, a fact that is the critical enabler of quantum wells, wires, and dots. The interfacial quality achieved as a result of heteroepitaxial growth allows new combinations of materials with complementary properties, which enables the design and realization of functionalities that are not available in the single-phase constituents. Here we show that organohalide perovskites and preformed colloidal quantum dots, combined in the solution phase, produce epitaxially aligned \\'dots-in-a-matrix\\' crystals. Using transmission electron microscopy and electron diffraction, we reveal heterocrystals as large as about 60 nanometres and containing at least 20 mutually aligned dots that inherit the crystalline orientation of the perovskite matrix. The heterocrystals exhibit remarkable optoelectronic properties that are traceable to their atom-scale crystalline coherence: photoelectrons and holes generated in the larger-bandgap perovskites are transferred with 80% efficiency to become excitons in the quantum dot nanocrystals, which exploit the excellent photocarrier diffusion of perovskites to produce bright-light emission from infrared-bandgap quantum-tuned materials. By combining the electrical transport properties of the perovskite matrix with the high radiative efficiency of the quantum dots, we engineer a new platform to advance solution-processed infrared optoelectronics.

  19. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  20. Achats de biens et services des organisations internationales dans les pays industrialisés et les économies émergentes

    Directory of Open Access Journals (Sweden)

    Gilles Carbonnier

    2013-08-01

    Full Text Available Cet article examine l’évolution des achats de biens et services des organisations multilatérales auprès de fournisseurs établis dans les pays industrialisés et les économies émergentes. Il présente les résultats d’une étude empirique – première du genre – sur les facteurs explicatifs des inégalités entre pays. Les différences s’expliquent notamment par la force du secteur manufacturier et les relations d’affaires établies dans le passé. Les résultats laissent penser que les contributions versées par les pays donateurs peuvent avoir une influence positive sur les achats de biens et services, nonobstant le fait que les organisations multilatérales recourent à des procédures d’appels d’offres internationaux. La proximité géographique, les affinités culturelles et linguistiques et la présence dans le pays du siège d’une organisation multilatérale jouent également un rôle positif. Les achats de biens et services des agences multilatérales peuvent être considérés comme une retombée indirecte de l’aide publique au développement (APD. Alors que nombre d’entre eux font face à de sérieuses difficultés économiques et contraintes budgétaires, documenter un tel « retour sur investissement » peut contribuer à convaincre les décideurs politiques d’augmenter – ou simplement de ne pas réduire – les budgets d’APD. De tels arguments doivent toutefois demeurer marginaux par rapport aux questions centrales de la pertinence et l’efficacité de l’aide, et des performances des organisations multilatérales.

  1. Producción y percepción de bienes públicos en la lógica de la acción colectiva

    Directory of Open Access Journals (Sweden)

    Jordana, Jacint

    2007-04-01

    Full Text Available Public goods having different proprieties produce different problems of collective action. This hypothesis has been discussed from different analytical perspectives and we examine their arguments, aiming to deepen our theoretical understanding about the logic of collective action. In this paper we look for similarities and differences regarding their use of concepts and expected results. Simultaneously, we examine the link between different public goods and the interdependent behavior of individuals. To this purpose, we also revisit the connections between production functions and consumption types in the case of public goods, as a mean to explore the potential development of more elaborated models in the theory of collective action, and suggest that more empirical contrast of these models is needed. Finally, we argue the importance for theoretical discussions to include a discussion about the impact of perception in the collective action models, considering systematic deviations to rational choice, and conclude that no single theory may address all collective action problems, but systematic patterns of behavior may be identified and empirically confirmed.

    Bienes públicos con distintas propiedades generan problemas diferentes de acción colectiva. Esta hipótesis ha sido discutida, desde distintas perspectivas analíticas, con el objeto de profundizar teóricamente sobre la lógica de la acción colectiva. En este trabajo se revisan las aportaciones recientes a esta cuestión, analizando sus puntos de encuentro y sus divergencias en cuanto a conceptos y resultados esperados. Asimismo, se examina la relación entre tipos distintos de bienes públicos y el comportamiento interdependiente de los individuos. Con este fin, los vínculos entre las funciones de producción y las formas de consumo de bienes públicos también son considerados, ya que permite desarrollar modelos más ambiciosos sobre la lógica de la acción colectiva. Finalmente

  2. La opacidad de los acuerdos generales de bienes y servicios en España Opacity of general agreements on goods and services in Spain

    Directory of Open Access Journals (Sweden)

    Román Andrés Umaña Peña

    2006-06-01

    Full Text Available Objetivo: Explorar la intensidad del debate parlamentario sobre el Acuerdo General de Comercio de Servicios (AGCS asumido por España ante la Organización Mundial del Comercio (OMC, y compararla con la del Acuerdo General de Bienes (GATT. Métodos: Búsqueda sistemática y análisis del contenido de todas las iniciativas parlamentarias sobre AGCS y GATT realizadas entre 1979 y 2004 en el Congreso de los Diputados y el Senado. Se calculó la frecuencia y porcentaje de iniciativas parlamentarias de ambos temas, resultado de su tramitación y tipo de iniciativa. Resultados: Se presentaron 185 iniciativas parlamentarias sobre los acuerdos multilaterales de bienes y servicios, de las que 120 se referían al GATT, 8 al AGCS y 57 a ambos acuerdos. La mayoría de las iniciativas no fueron discutidas (GATT, 71%; GATS, 55,4% o estuvieron sujetas a un debate político en el que apenas se dieron intervenciones por parte de los grupos parlamentarios. Conclusiones: A pesar de las implicaciones del acuerdo multilateral de servicios para la política sanitaria española, éste se ha asumido con escaso debate parlamentario previo, incluso menos que en el caso de su homólogo sobre bienes. Se requiere en este tema una intensificación de la función de control al gobierno.Objective: To explore the intensity of the debate in the Spanish Parliament on the General Agreement on Trade in Services (GATS developed by Spain and the World Trade Organization, and to compare it with the debate on the General Agreement on Tariffs and Trade (GATT. Methods: A systematic search and content analysis were performed of all parliamentary initiatives on GATS and GATT undertaken from 1979 to 2004 in the Spanish Parliament and Senate. The frequency and percentages of initiatives on both issues were calculated, and the final result and kinds of initiative were analyzed. Results: A total of 185 initiatives were presented in the Spanish Parliament on these agreements, of which 120 were

  3. Advancements in the Field of Quantum Dots

    Science.gov (United States)

    Mishra, Sambeet; Tripathy, Pratyasha; Sinha, Swami Prasad.

    2012-08-01

    Quantum dots are defined as very small semiconductor crystals of size varying from nanometer scale to a few micron i.e. so small that they are considered dimensionless and are capable of showing many chemical properties by virtue of which they tend to be lead at one minute and gold at the second minute.Quantum dots house the electrons just the way the electrons would have been present in an atom, by applying a voltage. And therefore they are very judiciously given the name of being called as the artificial atoms. This application of voltage may also lead to the modification of the chemical nature of the material anytime it is desired, resulting in lead at one minute to gold at the other minute. But this method is quite beyond our reach. A quantum dot is basically a semiconductor of very tiny size and this special phenomenon of quantum dot, causes the band of energies to change into discrete energy levels. Band gaps and the related energy depend on the relationship between the size of the crystal and the exciton radius. The height and energy between different energy levels varies inversely with the size of the quantum dot. The smaller the quantum dot, the higher is the energy possessed by it.There are many applications of the quantum dots e.g. they are very wisely applied to:Light emitting diodes: LEDs eg. White LEDs, Photovoltaic devices: solar cells, Memory elements, Biology : =biosensors, imaging, Lasers, Quantum computation, Flat-panel displays, Photodetectors, Life sciences and so on and so forth.The nanometer sized particles are able to display any chosen colour in the entire ultraviolet visible spectrum through a small change in their size or composition.

  4. Submonolayer Quantum Dot Infrared Photodetector

    Science.gov (United States)

    Ting, David Z.; Bandara, Sumith V.; Gunapala, Sarath D.; Chang, Yia-Chang

    2010-01-01

    A method has been developed for inserting submonolayer (SML) quantum dots (QDs) or SML QD stacks, instead of conventional Stranski-Krastanov (S-K) QDs, into the active region of intersubband photodetectors. A typical configuration would be InAs SML QDs embedded in thin layers of GaAs, surrounded by AlGaAs barriers. Here, the GaAs and the AlGaAs have nearly the same lattice constant, while InAs has a larger lattice constant. In QD infrared photodetector, the important quantization directions are in the plane perpendicular to the normal incidence radiation. In-plane quantization is what enables the absorption of normal incidence radiation. The height of the S-K QD controls the positions of the quantized energy levels, but is not critically important to the desired normal incidence absorption properties. The SML QD or SML QD stack configurations give more control of the structure grown, retains normal incidence absorption properties, and decreases the strain build-up to allow thicker active layers for higher quantum efficiency.

  5. Quantum dots as biophotonics tools.

    Science.gov (United States)

    Cesar, Carlos L

    2014-01-01

    This chapter provides a short review of quantum dots (QDs) physics, applications, and perspectives. The main advantage of QDs over bulk semiconductors is the fact that the size became a control parameter to tailor the optical properties of new materials. Size changes the confinement energy which alters the optical properties of the material, such as absorption, refractive index, and emission bands. Therefore, by using QDs one can make several kinds of optical devices. One of these devices transforms electrons into photons to apply them as active optical components in illumination and displays. Other devices enable the transformation of photons into electrons to produce QDs solar cells or photodetectors. At the biomedical interface, the application of QDs, which is the most important aspect in this book, is based on fluorescence, which essentially transforms photons into photons of different wavelengths. This chapter introduces important parameters for QDs' biophotonic applications such as photostability, excitation and emission profiles, and quantum efficiency. We also present the perspectives for the use of QDs in fluorescence lifetime imaging (FLIM) and Förster resonance energy transfer (FRET), so useful in modern microscopy, and how to take advantage of the usually unwanted blinking effect to perform super-resolution microscopy.

  6. Electromechanical transition in quantum dots

    Science.gov (United States)

    Micchi, G.; Avriller, R.; Pistolesi, F.

    2016-09-01

    The strong coupling between electronic transport in a single-level quantum dot and a capacitively coupled nanomechanical oscillator may lead to a transition towards a mechanically bistable and blocked-current state. Its observation is at reach in carbon-nanotube state-of-art experiments. In a recent publication [Phys. Rev. Lett. 115, 206802 (2015), 10.1103/PhysRevLett.115.206802] we have shown that this transition is characterized by pronounced signatures on the oscillator mechanical properties: the susceptibility, the displacement fluctuation spectrum, and the ring-down time. These properties are extracted from transport measurements, however the relation between the mechanical quantities and the electronic signal is not always straightforward. Moreover the dependence of the same quantities on temperature, bias or gate voltage, and external dissipation has not been studied. The purpose of this paper is to fill this gap and provide a detailed description of the transition. Specifically we find (i) the relation between the current-noise and the displacement spectrum; (ii) the peculiar behavior of the gate-voltage dependence of these spectra at the transition; (iii) the robustness of the transition towards the effect of external fluctuations and dissipation.

  7. Quantum dots for terahertz generation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H C; Aslan, B; Gupta, J A; Wasilewski, Z R; Aers, G C; SpringThorpe, A J; Buchanan, M [Institute for Microstructural Sciences, National Research Council, Ottawa, K1A 0R6 (Canada)], E-mail: h.c.liu@nrc.ca

    2008-09-24

    Nanostructures made of semiconductors, such as quantum wells and quantum dots (QD), are well known, and some have been incorporated in practical devices. Here we focus on novel structures made of QDs and related devices for terahertz (THz) generation. Their potential advantages, such as low threshold current density, high characteristic temperature, increased differential gain, etc, make QDs promising candidates for light emitting applications in the THz region. Our idea of using resonant tunneling through QDs is presented, and initial results on devices consisting of self-assembled InAs QDs in an undoped GaAs matrix, with a design incorporating a GaInNAs/GaAs short period superlattice, are discussed. Moreover, shallow impurities are also being explored for possible THz emission: the idea is based on the tunneling through bound states of individual donor or acceptor impurities in the quantum well. Initial results on devices having an AlGaAs/GaAs double-barrier resonant tunneling structure are discussed.

  8. ¿Cómo acercar los bienes patrimoniales a los ciudadanos? Educación Patrimonial, un campo emergente en la gestión del patrimonio cultural

    Directory of Open Access Journals (Sweden)

    Zaida García Valecillo

    2009-01-01

    Lamentablemente en las sociedades contemporáneas éste se aleja de la memoria de los ciudadanos. Por ello la gestión patrimonial busca la participación de los actores sociales, en donde la Educación Patrimonial puede ser una herramienta importante en este proceso. Esto implica desarrollar bases teóricas y metodológicas específicas que involucren a los ciudadanos en la sustentabilidad de las comunidades y sus bienes patrimoniales. En tal sentido, proponemos analizar la educación patrimonial como un campo emergente, a través de cuatro dimensiones pedagógicas que permitan sistematizar sus alcances y estrategias. Para luego articular dichas dimensiones en tres áreas de actuación educativa.

  9. Perspectivas del crecimiento urbano: la actividad comercial minorista y el transporte de bienes en la Zona Metropolitana de Querétaro (México

    Directory of Open Access Journals (Sweden)

    Eduardo Betanzo-Quezada

    2015-01-01

    Full Text Available Se muestran las perspectivas del crecimiento urbano, la actividad comercial minorista y su relación transversal con el transporte de bienes en la Zona Metropolitana de Querétaro (México. Con una metodología de análisis de información estadística de tipo agregado, se examinan esos determinantes con el objetivo de revelar sus tendencias en la ciudad. El paralelismo encontrado en las tendencias de comportamiento de los determinantes examinados conduce a concluir que es cada vez más necesario conectar al transporte urbano de carga con la planeación económica y urbana, y ubicarlo dentro de las prioridades de las administraciones gubernamentales.

  10. Inorganic passivation and doping control in colloidal quantum dot photovoltaics

    KAUST Repository

    Hoogland, Sjoerd H.

    2012-01-01

    We discuss strategies to reduce midgap trap state densities in colloidal quantum dot films and requirements to control doping type and magnitude. We demonstrate that these improvements result in colloidal quantum dot solar cells with certified 7.0% efficiency.

  11. Photoluminescence of carbon dots from mesoporous silica

    Science.gov (United States)

    Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

    2016-09-01

    Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

  12. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    OpenAIRE

    Z. O. Lipatova; E. V. Kolobkova; V. A. Aseev

    2015-01-01

    Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been fou...

  13. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Leosson, K.; Birkedal, Dan

    2003-01-01

    We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot...... coherence. The inferred homogeneous line widths are significantly smaller than the line widths usually observed in the photoluminescence from single quantum dots indicating an additional inhomogeneours broadening mechanism in the latter....

  14. Quantum Dots and Their Multimodal Applications: A Review

    OpenAIRE

    Holloway, Paul H; Teng-Kuan Tseng; Lei Qian; Debasis Bera

    2010-01-01

    Semiconducting quantum dots, whose particle sizes are in the nanometer range, have very unusual properties. The quantum dots have band gaps that depend in a complicated fashion upon a number of factors, described in the article. Processing-structure-properties-performance relationships are reviewed for compound semiconducting quantum dots. Various methods for synthesizing these quantum dots are discussed, as well as their resulting properties. Quantum states and confinement of their excitons ...

  15. Filtering algorithm for dotted interferences

    Energy Technology Data Exchange (ETDEWEB)

    Osterloh, K., E-mail: kurt.osterloh@bam.de [Federal Institute for Materials Research and Testing (BAM), Division VIII.3, Radiological Methods, Unter den Eichen 87, 12205 Berlin (Germany); Buecherl, T.; Lierse von Gostomski, Ch. [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie, Walther-Meissner-Str. 3, 85748 Garching (Germany); Zscherpel, U.; Ewert, U. [Federal Institute for Materials Research and Testing (BAM), Division VIII.3, Radiological Methods, Unter den Eichen 87, 12205 Berlin (Germany); Bock, S. [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie, Walther-Meissner-Str. 3, 85748 Garching (Germany)

    2011-09-21

    An algorithm has been developed to remove reliably dotted interferences impairing the perceptibility of objects within a radiographic image. This particularly is a major challenge encountered with neutron radiographs collected at the NECTAR facility, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II): the resulting images are dominated by features resembling a snow flurry. These artefacts are caused by scattered neutrons, gamma radiation, cosmic radiation, etc. all hitting the detector CCD directly in spite of a sophisticated shielding. This makes such images rather useless for further direct evaluations. One approach to resolve this problem of these random effects would be to collect a vast number of single images, to combine them appropriately and to process them with common image filtering procedures. However, it has been shown that, e.g. median filtering, depending on the kernel size in the plane and/or the number of single shots to be combined, is either insufficient or tends to blur sharp lined structures. This inevitably makes a visually controlled processing image by image unavoidable. Particularly in tomographic studies, it would be by far too tedious to treat each single projection by this way. Alternatively, it would be not only more comfortable but also in many cases the only reasonable approach to filter a stack of images in a batch procedure to get rid of the disturbing interferences. The algorithm presented here meets all these requirements. It reliably frees the images from the snowy pattern described above without the loss of fine structures and without a general blurring of the image. It consists of an iterative, within a batch procedure parameter free filtering algorithm aiming to eliminate the often complex interfering artefacts while leaving the original information untouched as far as possible.

  16. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  17. AHE measurements of very thin films and nanosized dots

    NARCIS (Netherlands)

    Kikuchi, N.; Murillo, R.; Lodder, J.C.

    2005-01-01

    In this paper we present anomalous Hall effect analysis from very thin Co (0.5 nm) film, Co/Pt multilayers and large areas of nanosized dots as well as from a few magnetic dots having a diameter of 120 nm. The dot arrayis prepared from Co/Pt multilayer by using laser interference lithography (LIL) w

  18. Evidence for curvilinear interpolation from dot alignment judgements

    NARCIS (Netherlands)

    van Assen, MA; Vos, PG

    1999-01-01

    Visual interpolation between dots responsible for rectilinear versus curvilinear contour interpretation was examined with the psychophysical forced directional response (FDR) paradigm. Regular four-dot polygon segments, together with a target dot, were presented to the subjects for 150 ms. Subjects

  19. Toward structurally defined carbon dots as ultracompact fluorescent probes.

    Science.gov (United States)

    LeCroy, Gregory Ethan; Sonkar, Sumit Kumar; Yang, Fan; Veca, L Monica; Wang, Ping; Tackett, Kenneth N; Yu, Jing-Jiang; Vasile, Eugeniu; Qian, Haijun; Liu, Yamin; Luo, Pengju George; Sun, Ya-Ping

    2014-05-27

    There has been much discussion on the need to develop fluorescent quantum dots (QDs) as ultracompact probes, with overall size profiles comparable to those of the genetically encoded fluorescent tags. In the use of conventional semiconductor QDs for such a purpose, the beautifully displayed dependence of fluorescence color on the particle diameter becomes a limitation. More recently, carbon dots have emerged as a new platform of QD-like fluorescent nanomaterials. The optical absorption and fluorescence emissions in carbon dots are not bandgap in origin, different from those in conventional semiconductor QDs. The absence of any theoretically defined fluorescence color-dot size relationships in carbon dots may actually be exploited as a unique advantage in the size reduction toward having carbon dots serve as ultracompact QD-like fluorescence probes. Here we report on carbon dots of less than 5 nm in the overall dot diameter with the use of 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) molecules for the carbon particle surface passivation. The EDA-carbon dots were found to be brightly fluorescent, especially over the spectral range of green fluorescent protein. These aqueous soluble smaller carbon dots also enabled more quantitative characterizations, including the use of solution-phase NMR techniques, and the results suggested that the dot structures were relatively simple and better-defined. The potential for these smaller carbon dots to serve as fluorescence probes of overall sizes comparable to those of fluorescent proteins is discussed.

  20. Coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian;

    . An alternative approach is to couple the quantum dot directly to the propagating mode of a photonic waveguide. We demonstrate the coupling of single quantum dots to a photonic crystal waveguide using time-resolved spontaneous emission measurements. A pronounced effect is seen in the decay rates of dots coupled...

  1. Charged-Exciton Complexes in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2001-01-01

    It is known experimentally that stable charged-exciton complexes can exist in low-dimensional semiconductor nanostructures. Much less is known about the properties of such charged-exciton complexes since three-body problems are very difficult to be solved, even numerically. Here we introduce the correlated hyperspherical harmonics as basis functions to solve the hyperangular equation for negatively and positively charged excitons (trions) in a harmonic quantum dot. By using this method, we have calculated the energy spectra of the low-lying states of a charged exciton as a function of the radius of quantum dot. Based on symmetry analysis, the level crossover as the dot radius increases can be fully explained as the results of symmetry constraint.``

  2. Barrier Li Quantum Dots in Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    LIUYi-Min; LIXiao-Zhu; YANWen-Hong; BAOCheng-Guang

    2003-01-01

    The methods for the few-body system are introduced to investigate the states of the barrier Li quantum dots (QDs) in an arbitrary strength of magnetic field. The configuration, which consists of a positive ion located on the z-axis at a distaneed from the two-dimensional QD plane (the x-y plane) and three electrons in the dot plane bound by the positive ion, is called a barrier Li center. The system, which consists of three electrons in the dot plane bound by the ion,is called a barrier Li QD. The dependence of energy of the state of the barrier Li QD on an external magnetic field B and the distance d is obtained. The angular momentum L of the ground states is found to jump not only with the variation orB but also with d.

  3. Branch management into micropipeline joint dot

    Directory of Open Access Journals (Sweden)

    Dimitar Tyanev

    2011-11-01

    Full Text Available This paper considers problems related to hardware implementation of computational process with conditional jumps. Hardware refers to asynchronous pipeline organization at microoperational level. Exploration is dedicated to one of the tasks presented in (Tyanev, D., 2009 concerning to micropipeline controller design to control micropipeline stage into joint dot of branch algorithm. Joint dot is the point at which few preceding branches are combined. It appears inevitably into conditional jump structures and this is the reason for the actuality of its problem. Analysis of this new task is presented and request arbitration functioning principles are formulated for the incoming to joint dot requests. The arbiter is responsible for the fair choice on which depends steady peformance of separate pipeline brances. Paper also describes pipeline controller synthesis and analysis of its operation in two variants: about 2-phase and 4-phase data transfer protocol. The synthesized asynchronous arbiter scheme is invariant to the type of pipeline protocol.

  4. Angiogenic Profiling of Synthesized Carbon Quantum Dots.

    Science.gov (United States)

    Shereema, R M; Sruthi, T V; Kumar, V B Sameer; Rao, T P; Shankar, S Sharath

    2015-10-20

    A simple method was employed for the synthesis of green luminescent carbon quantum dots (CQDs) from styrene soot. The CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopy. The prepared carbon quantum dots did not show cellular toxicity and could successfully be used for labeling cells. We also evaluated the effects of carbon quantum dots on the process of angiogenesis. Results of a chorioallantoic membrane (CAM) assay revealed the significant decrease in the density of branched vessels after their treatment with CQDs. Further application of CQDs significantly downregulated the expression levels of pro-angiogenic growth factors like VEGF and FGF. Expression of VEGFR2 and levels of hemoglobin were also significantly lower in CAMs treated with CQDs, indicating that the CQDs inhibit angiogenesis. Data presented here also show that CQDs can selectively target cancer cells and therefore hold potential in the field of cancer therapy.

  5. Quantum Dots in Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Sollner, Immo Nathanael

    This Thesis is focused on the study of quantum electrodynamics in photonic crystal waveguides. We investigate the interplay between a single quantum dot and the fundamental mode of the photonic crystal waveguide. We demonstrate experimental coupling eciencies for the spontaneous emission...... into the mode exceeding 98% for emitters spectrally close to the band-edge of the waveguide mode. In addition we illustrate the broadband nature of the underlying eects, by obtaining coupling eciencies above 90% for quantum dots detuned from the band edge by as far as 20nm. These values are in good agreement...... quantum-dot-waveguide coupling. Such a structure is ideally suited for a number of applications in quantum information processing and among others we propose an on-chip spin-photon interface, a single photon transistor, and a deterministic cNOT gate....

  6. Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications.

    Science.gov (United States)

    Zheng, Xin Ting; Ananthanarayanan, Arundithi; Luo, Kathy Qian; Chen, Peng

    2015-04-08

    The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications.

  7. Resonant tunneling in graphene pseudomagnetic quantum dots.

    Science.gov (United States)

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  8. Cadmium telluride quantum dots advances and applications

    CERN Document Server

    Donegan, John

    2013-01-01

    Optical Properties of Bulk and Nanocrystalline Cadmium Telluride, Núñez Fernández and M.I. VasilevskiyAqueous Synthesis of Colloidal CdTe Nanocrystals, V. Lesnyak, N. Gaponik, and A. EychmüllerAssemblies of Thiol-Capped CdTe Nanocrystals, N. GaponikFörster Resonant Energy Transfer in CdTe Nanocrystal Quantum Dot Structures, M. Lunz and A.L. BradleyEmission of CdTe Nanocrystals Coupled to Microcavities, Y.P. Rakovich and J.F. DoneganBiological Applications of Cadmium Telluride Semiconductor Quantum Dots, A. Le Cign

  9. Polymers in Carbon Dots: A Review

    Directory of Open Access Journals (Sweden)

    Yiqun Zhou

    2017-02-01

    Full Text Available Carbon dots (CDs have been widely studied since their discovery in 2004 as a green substitute of the traditional quantum dots due to their excellent photoluminescence (PL and high biocompatibility. Meanwhile, polymers have increasingly become an important component for both synthesis and modification of CDs to provide polymeric matrix and enhance their PL property. Furthermore, critical analysis of composites of CDs and polymers has not been available. Herein, in this review, we summarized the use of polymers in the synthesis and functionalization of CDs, and the applications of these CDs in various fields.

  10. Bilayer graphene quantum dot defined by topgates

    Energy Technology Data Exchange (ETDEWEB)

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

    2014-06-21

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  11. Mitigation of quantum dot cytotoxicity by microencapsulation.

    Directory of Open Access Journals (Sweden)

    Amelia Romoser

    Full Text Available When CdSe/ZnS-polyethyleneimine (PEI quantum dots (QDs are microencapsulated in polymeric microcapsules, human fibroblasts are protected from acute cytotoxic effects. Differences in cellular morphology, uptake, and viability were assessed after treatment with either microencapsulated or unencapsulated dots. Specifically, QDs contained in microcapsules terminated with polyethylene glycol (PEG mitigate contact with and uptake by cells, thus providing a tool to retain particle luminescence for applications such as extracellular sensing and imaging. The microcapsule serves as the "first line of defense" for containing the QDs. This enables the individual QD coating to be designed primarily to enhance the function of the biosensor.

  12. Spectroscopic characteristics of carbon dots (C-dots) derived from carbon fibers and conversion to sulfur-bridged C-dots nanosheets.

    Science.gov (United States)

    Vinci, John C; Ferrer, Ivonne M; Guterry, Nathan W; Colón, Verónica M; Destino, Joel F; Bright, Frank V; Colón, Luis A

    2015-09-01

    We synthesized sub-10 nm carbon nanoparticles (CNPs) consistent with photoluminescent carbon dots (C-dots) from carbon fiber starting material. The production of different C-dots fractions was monitored over seven days. During the course of the reaction, one fraction of C-dots species with relatively high photoluminescence was short-lived, emerging during the first hour of reaction but disappearing after one day of reaction. Isolation of this species during the first hour of the reaction was crucial to obtaining higher-luminescent C-dots species. When the reaction proceeded for one week, the appearance of larger nanostructures was observed over time, with lateral dimensions approaching 200 nm. The experimental evidence suggests that these larger species are formed from small C-dot nanoparticles bridged together by sulfur-based moieties between the C-dot edge groups, as if the C-dots polymerized by cross-linking the edge groups through sulfur bridges. Their size can be tailored by controlling the reaction time. Our results highlight the variety of CNP products, from sub-10 nm C-dots to ~200 nm sulfur-containing carbon nanostructures, that can be produced over time during the oxidation reaction of the graphenic starting material. Our work provides a clear understanding of when to stop the oxidation reaction during the top-down production of C-dots to obtain highly photoluminescent species or a target average particle size.

  13. Photoluminescence studies of single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1999-01-01

    Semiconductor quantum dots are considered a promising material system for future optical devices and quantum computers. We have studied the low-temperature photoluminescence properties of single InGaAs quantum dots embedded in GaAs. The high spatial resolution required for resolving single dots...... to resolve luminescence lines from individual quantum dots, revealing an atomic-like spectrum of sharp transition lines. A parameter of fundamental importance is the intrinsic linewidth of these transitions. Using high-resolution spectroscopy we have determined the linewidth and investigated its dependence...... on temperature, which gives information about how the exciton confined to the quantum dot interacts with the surrounding lattice....

  14. The Influence of Formulating a Damping Solution on Dot Gain

    Directory of Open Access Journals (Sweden)

    Povilas Mikalainis

    2011-02-01

    Full Text Available Difference in dot gain using various additives to the damping solution was investigated on two offset web presses. Dot gain was measured using a densitometer and calculated considering CIE L*a*b* coordinates. It was found that while using a non alcohol additive instead of the alcohol one, dot gain became smaller and printing stability was lower. Changes in dot gain depend on the ink that may vary in colours. The influence of changes in dot gain on the colour was determined. Besides, it was found that differences in colour were unacceptable in many cases.Article in Lithuanian

  15. Photoluminescent carbon dots from 1,4-addition polymers.

    Science.gov (United States)

    Jiang, Zhiqiang; Nolan, Andrew; Walton, Jeffrey G A; Lilienkampf, Annamaria; Zhang, Rong; Bradley, Mark

    2014-08-25

    Photoluminescent carbon dots were synthesised directly by thermopyrolysis of 1,4-addition polymers, allowing precise control of their properties. The effect of polymer composition on the properties of the carbon dots was investigated by TEM, IR, XPS, elemental analysis and fluorescence analysis, with carbon dots synthesised from nitrogen-containing polymers showing the highest fluorescence. The carbon dots with high nitrogen content were observed to have strong fluorescence in the visible region, and culture with cells showed that the carbon dots were non-cytotoxic and readily taken up by three different cell lines.

  16. Electrically addressing a single self-assembled quantum dot

    CERN Document Server

    Ellis, D J P; Atkinson, P; Ritchie, D A; Shields, A J

    2006-01-01

    We report on the use of an aperture in an aluminum oxide layer to restrict current injection into a single self-assembled InAs quantum dot, from an ensemble of such dots within a large mesa. The insulating aperture is formed through the wet-oxidation of a layer of AlAs. Under photoluminescence we observe that only one quantum dot in the ensemble exhibits a Stark shift, and that the same single dot is visible under electroluminescence. Autocorrelation measurements performed on the electroluminescence confirm that we are observing emission from a single quantum dot.

  17. Sensitivity of quantum-dot semiconductor lasers to optical feedback.

    Science.gov (United States)

    O'Brien, D; Hegarty, S P; Huyet, G; Uskov, A V

    2004-05-15

    The sensitivity of quantum-dot semiconductor lasers to optical feedback is analyzed with a Lang-Kobayashi approach applied to a standard quantum-dot laser model. The carriers are injected into a quantum well and are captured by, or escape from, the quantum dots through either carrier-carrier or phonon-carrier interaction. Because of Pauli blocking, the capture rate into the dots depends on the carrier occupancy level in the dots. Here we show that different carrier capture dynamics lead to a strong modification of the damping of the relaxation oscillations. Regions of increased damping display reduced sensitivity to optical feedback even for a relatively large alpha factor.

  18. High-resolution photoluminescence studies of single semiconductor quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis;

    2000-01-01

    Semiconductor quantum dots, especially those formed by self-organized growth, are considered a promising material system for future optical devices [1] and the optical properties of quantum dot ensembles have been investigated in detail over the past years. Recently, considerable interest has...... developed in the study of single quantum dots, characterized by sharp atomic-like transition lines revealing their zero-dimensional density of states. Substantial information about the fundamental properties of individual quantum dots, as well as their interactions with other dots and the host lattice, can...

  19. A study of the lunisolar secular resonance $2\\dot{\\omega}+\\dot{\\Omega}=0$

    CERN Document Server

    Celletti, Alessandra

    2016-01-01

    The dynamics of small bodies around the Earth has gained a renewed interest, since the awareness of the problems that space debris can cause in the nearby future. A relevant role in space debris is played by lunisolar secular resonances, which might contribute to an increase of the orbital elements, typically of the eccentricity. We concentrate our attention on the lunisolar secular resonance described by the relation $2\\dot{\\omega}+\\dot{\\Omega}=0$, where $\\omega$ and $\\Omega$ denote the argument of perigee and the longitude of the ascending node of the space debris. We introduce three different models with increasing complexity. We show that the growth in eccentricity, as observed in space debris located in the MEO region at the inclination about equal to $56^\\circ$, can be explained as a natural effect of the secular resonance $2\\dot{\\omega}+\\dot{\\Omega}=0$, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  20. Conducta típica e imputación objetiva en el delito de alzamiento de bienes: una contribución normativista a la dogmática de los delitos de insolvencia

    OpenAIRE

    2014-01-01

    La tesis contiene un análisis dogmático del tipo de alzamiento de bienes, cuyos puntos de partida y conclusiones pueden extenderse a los demás tipos penales que se encuentran dentro del género de las insolvencias punibles. Se comienza por un estudio del estado de la cuestión que incluye el objeto de protección y la forma de afectación del bien jurídico, criticando las posturas dominantes de la doctrina como de la jurisprudencia. En segundo lugar se aborda el problema relativo a la natural...

  1. La Repercusión del Valor Razonable de los Bienes Inmuebles en la Utilidad de los Estados Financieros: Una Nota de Investigación

    Directory of Open Access Journals (Sweden)

    Andrés Navarro Galera

    2009-06-01

    Full Text Available La elección en la reciente reforma contable española del criterio de valor razonable en lugar del coste histórico como base de valoración para determinados activos ha generado cierta controversia. Este trabajo estudia la posible incidencia de la adopción del valor razonable para el registro contable de los bienes inmuebles sobre la relevancia y la fiabilidad de la información financiera. El estudio empírico está basado en una encuesta sobre las percepciones de 151 responsables de la contabilidad de empresas españolas del sector de la construcción sobre la utilidad y fiabilidad de la información financiera basada en el valor razonable. El análisis de los resultados nos ha permitido concluir que, respecto al coste histórico, los responsables de contabilidad perciben que el valor razonable de los bienes inmuebles generaría estados financieros más útiles para representar la imagen fiel del patrimonio de la empresa. No obstante, los encuestados conciben la información financiera bajo valor razonable como menos objetiva y verificable. Asimismo, hemos comprobado que el tamaño de la empresa puede influir en la opinión de la repercusión del valor razonable sobre la relevancia y fiabilidad de los estados financieros.The option in the recent Spanish regulation for fair value over historical cost, as the preferred measurement basis for some assets, has raised some controversy. This paper studies the effects on accounting information relevance and reliability of fair value accounting for investment properties. The empirical study is based on a questionnairebased survey of the perceptions of 151 Spanish accountants in the building industry about the usefulness and reliability of fair value accounting. The analysis of results allows us concluding that accountants perceive that the usefulness of financial statements increases when investment property is valued on a fair value basis, compared with a historical cost basis. However, respondents

  2. Ciencia prohibida... ciencia buscada (A propósito de La ciencia del bien y del mal de Javier Echeverría

    Directory of Open Access Journals (Sweden)

    Gómez Pin, Víctor

    2007-06-01

    Full Text Available A labyrinth was the infinite for Leibniz (who declares on several occasions that,as much from the angle of the infinite large as from that of the infinite small, infinity is nothing but a fiction in the attempts of thought to explain the phenomena. But another labyrinth was also for him the problem of the evilness, together with the correlative problem of goodness. Used, since he was a young mathematician, to the Leibnizian puzzle of the infinite, Javier Echeverría faces now the second labyrinth. And he approaches the subject by restoring the biblical myth of the tree that hides the mystery. Taken implicitly the opposite point of view that leads Kant to assert the intrinsic division of the reason, Echeverría, from the very title of his book, aims at goodness and evilness as effective goals for science. In this paper we discuss some implications of Echeverría’s bet.

    Un laberinto era el infinito para Leibniz (quien afirma en varias ocasiones que tanto lo infinitamente grande como lo infinitamente pequeño no son sino ficciones para el pensamiento que busca la explicación de los fenómenos pero laberinto era asimismo, para él, la cuestión del mal, indisociable de problema del bien. Curtido, desde sus años de joven matemático, en el leibniziano puzzle del infinito y el continuo, Javier Echeverría se confronta ahora al segundo laberinto. Y lo hace restaurando el bíblico relato del árbol cuyo fruto escondería el misterio. Tomando implícitamente una vía opuesta a la que conduce a la kantiana división de la razón, Echeverría apunta a hacer de la polaridad bien-mal objeto de efectiva ciencia. En este escrito discutimos alguna de las implicaciones de su apuesta.

  3. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Neetu, E-mail: singh.neetu1985@gmail.com; Kapoor, Avinashi [Department of Electronic Science, University of Delhi South Campus, New Delhi-110 021 (India); Kumar, Vinod [Department of Physics, University of the Free State, Bloemfontein, ZA9300 (South Africa); Mehra, R. M. [School of Engineering and Technology, Sharda University, Greater Noida-201 306, U.P. (India)

    2014-04-24

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  4. Bien rédiger

    CERN Document Server

    Humbert, Jean-Louis

    1992-01-01

    Vous avez à rédiger un rapport, un résumé, une note de service ou un compte rendu de réunion. Vous avez un examen écrit à préparer... Ce guide, enrichi de nombreux exercices, vous donne toutes les règles pour : . Formuler votre pensée . Structurer votre texte . Construire vos phrases . Choisir le mot juste.

  5. Optical Properties of Quantum-Dot-Doped Liquid Scintillators

    CERN Document Server

    Aberle, C; Weiss, S; Winslow, L

    2013-01-01

    Semiconductor nanoparticles (quantum dots) were studied in the context of liquid scintillator development for upcoming neutrino experiments. The unique optical and chemical properties of quantum dots are particularly promising for the use in neutrinoless double beta decay experiments. Liquid scintillators for large scale neutrino detectors have to meet specific requirements which are reviewed, highlighting the peculiarities of quantum-dot-doping. In this paper, we report results on laboratory-scale measurements of the attenuation length and the fluorescence properties of three commercial quantum dot samples. The results include absorbance and emission stability measurements, improvement in transparency due to filtering of the quantum dot samples, precipitation tests to isolate the quantum dots from solution and energy transfer studies with quantum dots and the fluorophore PPO.

  6. Producing Quantum Dots by Spray Pyrolysis

    Science.gov (United States)

    Banger, Kulbinder; Jin, Michael H.; Hepp, Aloysius

    2006-01-01

    An improved process for making nanocrystallites, commonly denoted quantum dots (QDs), is based on spray pyrolysis. Unlike the process used heretofore, the improved process is amenable to mass production of either passivated or non-passivated QDs, with computer control to ensure near uniformity of size.

  7. Enabling biomedical research with designer quantum dots

    NARCIS (Netherlands)

    Tomczak, N.; Janczewski, D.; Dorokhin, D.V.; Han, M-Y; Vancso, G.J.; Navarro, Melba; Planell, Josep A.

    2012-01-01

    Quantum Dots (QDs) are a new class of semiconductor nanoparticulate luminophores, which are actively researched for novel applications in biology and nanomedicine. In this review, the recent progress in the design and applications of QD labels for in vitro and in vivo imaging of cells is presented.

  8. Electron Scattering in Intrananotube Quantum Dots

    NARCIS (Netherlands)

    Buchs, G.; Bercioux, D.; Ruffieux, P.; Gröning, P.; Grabert, H.; Gröning, O.

    2009-01-01

    Intratube quantum dots showing particle-in-a-box-like states with level spacings up to 200 meV are realized in metallic single-walled carbon nanotubes by means of low dose medium energy Ar+ irradiation. Fourier-transform scanning tunneling spectroscopy compared to results of a Fabry-Perot electron r

  9. Quantum dot waveguides: ultrafast dynamics and applications

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2009-01-01

    In this paper we analyze, based on numerical simulations, the dynamics of semiconductor devices incorporating quantum dots (QDs). In particular we emphasize the unique ultrafast carrier dynamics occurring between discrete QD bound states, and its influence on QD semiconductor optical amplifiers...... (SOAs). Also the possibility of realizing an all-optical regenerator by incorporating a QD absorber section in an amplifier structure is discussed....

  10. Amphoteric CdSe nanocrystalline quantum dots.

    Science.gov (United States)

    Islam, Mohammad A

    2008-06-25

    The nanocrystal quantum dot (NQD) charge states strongly influence their electrical transport properties in photovoltaic and electroluminescent devices, optical gains in NQD lasers, and the stability of the dots in thin films. We report a unique electrostatic nature of CdSe NQDs, studied by electrophoretic methods. When we submerged a pair of metal electrodes, in a parallel plate capacitor configuration, into a dilute solution of CdSe NQDs in hexane, and applied a DC voltage across the pair, thin films of CdSe NQDs were deposited on both the positive and the negative electrodes. Extensive characterizations including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman studies revealed that the films on both the positive and the negative electrodes were identical in every respect, clearly indicating that: (1) a fraction (<1%) of the CdSe NQDs in free form in hexane solution are charged and, more importantly, (2) there are equal numbers of positive and negative CdSe NQDs in the hexane solution. Experiments also show that the number of deposited dots is at least an order of magnitude higher than the number of initially charged dots, indicating regeneration. We used simple thermodynamics to explain such amphoteric nature and the charging/regeneration of the CdSe NQDs.

  11. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  12. Decoherence in Nearly-Isolated Quantum Dots

    DEFF Research Database (Denmark)

    Folk, J.; M. Marcus, C.; Harris jr, J.

    2000-01-01

    Decoherence in nearly-isolated GaAs quantum dots is investigated using the change in average Coulomb blockade peak height upon breaking time-reversal symmetry. The normalized change in average peak height approaches the predicted universal value of 1/4 at temperatures well below the single...

  13. System and method for making quantum dots

    KAUST Repository

    Bakr, Osman M.

    2015-05-28

    Embodiments of the present disclosure provide for methods of making quantum dots (QDs) (passivated or unpassivated) using a continuous flow process, systems for making QDs using a continuous flow process, and the like. In one or more embodiments, the QDs produced using embodiments of the present disclosure can be used in solar photovoltaic cells, bio-imaging, IR emitters, or LEDs.

  14. Saturating optical resonances in quantum dots

    Science.gov (United States)

    Nair, Selvakumar V.; Rustagi, K. C.

    Optical bistability in quantum dots, recently proposed by Chemla and Miller, is studied in a two-resonance model. We show that for such classical electromagnetic resonances the applicability of a two-resonance model is far more restrictive than for those in atoms.

  15. Single Molecule Applications of Quantum Dots

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Elmelund; Jauffred, Liselotte; Brewer, Jonathan R.

    2013-01-01

    Fluorescent nanocrystals composed of semiconductor materials were first introduced for biological applications in the late 1990s. The focus of this review is to give a brief survey of biological applications of quantum dots (QDs) at the single QD sensitivity level. These are described as follows:...

  16. Carbon dots (C-dots) from cow manure with impressive subcellular selectivity tuned by simple chemical modification.

    Science.gov (United States)

    D'Angelis do E S Barbosa, Cintya; Corrêa, José R; Medeiros, Gisele A; Barreto, Gabrielle; Magalhães, Kelly G; de Oliveira, Aline L; Spencer, John; Rodrigues, Marcelo O; Neto, Brenno A D

    2015-03-23

    Improved cellular selectivity for nucleoli staining was achieved by simple chemical modification of carbon dots (C-dots) synthesized from waste carbon sources such as cow manure (or from glucose). The C-dots were characterized and functionalized (amine-passivated) with ethylenediamine, affording amide bonds that resulted in bright green fluorescence. The new modified C-dots were successfully applied as selective live-cell fluorescence imaging probes with impressive subcellular selectivity and the ability to selectively stain nucleoli in breast cancer cell lineages (MCF-7). The C-dots were also tested in four other cellular models and showed the same cellular selection in live-cell imaging experiments.

  17. Aspectos generales del régimen de los bienes del litoral marítimo. Competencias y limitaciones sobre el Derecho de propiedad

    Directory of Open Access Journals (Sweden)

    Sebastián Barreto Cifuentes

    2013-07-01

    Full Text Available El concepto de “propiedad”, tradicionalmente estudiado con la lógica del Derecho privado, ha sufrido cambios internos (la función social como núcleo esencial y externos (las limitaciones administrativas que hacen necesario estudiarlo con herramientas lógicas y metodológicas del Derecho público. Se debe considerar que un derecho absoluto e ilimitado no requiere mayor atención por parte de la disciplina del Derecho público. La armonización y articulación de los derechos del propietario con las competencias asignadas a las autoridades administrativas, exige una particular atención para proteger los derechos ciudadanos. En desarrollo de lo mencionado, se ha realizado un corto estudio sobre los bienes del litoral marítimo, en particular de las competencias asignadas a las autoridades administrativas sobre estas áreas, así como el límite de estas competencias. También se presentará el análisis de algunos casos reales y potenciales en los cuales se hace necesaria la aplicación de garantías procesales y sustanciales para el respeto de los derechos de los propietarios.

  18. Validación del Índice de Bien-estar Personal en personas con enfermedad renal crónica

    Directory of Open Access Journals (Sweden)

    Luís Manuel Mota de Sousa

    Full Text Available Objetivo: verificar las propiedades psicométricas del Índice de bien-estar personal (IBP en personas con enfermedad renal crónica en programa de hemodiálisis. Método: Se trata de un estudio metodológico. La muestra aleatoria es constituida por 171 personas con Enfermedad Renal Crónica (ERC sometida a hemodiálisis en dos clínicas en la región de Lisboa, Portugal. La recogida de datos fue realizada entre mayo y junio de 2015. Se evaluaron las propiedades psicométricas: validad (constructo, predictiva convergente, y discriminativa, confiabilidad por medio de la consistencia interna (α de Cronbach y estabilidad (Coeficiente de Correlación de Spearman-Brown y Coeficiente de Correlación Intraclasse (CCI. Resultados: El IBP presenta una dimensión ajustada a los datos. La satisfacción con la salud es lo que más contribuye para el IBP. Tiene validad convergente con Felicidad Subjetiva y Afecto Positivo y Afecto Negativo. Tiene poder discriminativo en la nacionalidad. El a Cronbach fue de 0,82. Teste Re-teste para cuestionario 0, 92 e CCI= 0,95, para entrevista 0,85 y CCI= 0,89. Conclusiones: La versión portuguesa del IBP es válida y reproducible en personas con ERC, tanto por cuestionario como por entrevista.

  19. Aspectos generales del régimen de los bienes del litoral marítimo. Competencias y limitaciones sobre el Derecho de propiedad

    Directory of Open Access Journals (Sweden)

    Sebastián Barreto Cifuentes

    2013-06-01

    Full Text Available El concepto de “propiedad”, tradicionalmente estudiado con la lógica del Derecho privado, ha sufrido cambios internos (la función social como núcleo esencial y externos (las limitaciones administrativas que hacen necesario estudiarlo con herramientas lógicas y metodológicas del Derecho público. Se debe considerar que un derecho absoluto e ilimitado no requiere mayor atención por parte de la disciplina del Derecho público. La armonización y articulación de los derechos del propietario con las competencias asignadas a las autoridades administrativas, exige una particular atención para proteger los derechos ciudadanos. En desarrollo de lo mencionado, se ha realizado un corto estudio sobre los bienes del litoral marítimo, en particular de las competencias asignadas a las autoridades administrativas sobre estas áreas, así como el límite de estas competencias. También se presentará el análisis de algunos casos reales y potenciales en los cuales se hace necesaria la aplicación de garantías procesales y sustanciales para el respeto de los derechos de los propietarios.

  20. Hacia una reconstrucción del diseño legislativo del inventario y avalúo de los bienes hereditarios en Cuba

    Directory of Open Access Journals (Sweden)

    Raúl José Vega Cardona

    2014-12-01

    Full Text Available El presente artículo parte de la necesidad de realizar un estudio sobre el contenido del inventario y avalúo como operación particional del caudal hereditario en Cuba, a raíz de las complejidades propias del instituto, las que no solo se manifiestan en el ámbito teórico doctrinal sino también en la configuración legal que del mismo hiciera el legislador cubano. En este sentido se aporta, a partir de una exposición doctrinal sobre el tema, un diagnóstico de las principales insuficiencias que en el ámbito sustantivo inciden en la deficitaria práctica de la determinación y valuación de los bienes hereditarios, y con ello el establecimiento de las posibles pautas que permitan perfeccionar el régimen jurídico de la institución objeto de análisis.

  1. Producción y consumo de bienes culturales: El caso de las artesanías urbanas de la Ciudad de Buenos Aires

    Directory of Open Access Journals (Sweden)

    Mónica B. Rotman

    2002-12-01

    Full Text Available Este artículo tiene por objeto reseñar algunos de los principales aspectos de un fenómeno cultural citadino: las artesanías urbanas feriales de la Ciudad de Buenos Aires. La problemática abordada contempla las instancias de la producción artesanal, la circulación de estos bienes con énfasis en las Ferias como sitios privilegiados del intercambio y ámbitos relevantes de sociabilidad y el consumo de artesanías. Consideramos que este tipo de producción, que constituye un fenómeno complejo, conforma una práctica cultural heterodoxa, recreando con códigos propios la sociabilidad híbrida que inducen las ciudades contemporáneas.The objective of this article is to outline some of the main aspects of an urban cultural phenomenon: the urban handicrafts from fairs in Buenos Aires city. The issues this paper addresses are handicraft production, the circulation of these goods with emphasis on fairs as privileged places of exchange, sociability and handicraft consumption. I consider this type of production a complex phenomena that shapes an heterodox cultural practice, recreating through its own codes the hybrid sociability that contemporary cities induce.

  2. Bienes básicos, mercancía patrón y tasa de ganancia en Piero Sraffa Basic goods, standard commodity and the rate of profit in Piero Sraffa

    Directory of Open Access Journals (Sweden)

    Supelano Sarmiento Alberto

    1996-06-01

    Full Text Available Este ensayo describe el papel de los bienes básicos y la mercancía patrón en el esquema de precios de producción propuesto por Piero Sraffa. Su tema central son los problemas relacionados con la interpretación de Homero Cuevas: la importancia de los bienes básicos y de los bienes de lujo en la determinación de los precios y la distribución del excedente; la composición y el papel de la mercancía patrón; las limitaciones de la distinción entre los dos tipos de bienes y del concepto de mercancía patrón y la supuesta imposibilidad de construir la mercancía patrón.This essay describes the role of basic goods and the standard commodity in the prices of production scheme proposed by Piero Sraffa. Its central theme concerns the problems related to the interpretation of Homero Cuevas: the importance of basic goods and luxury goods in the determination of prices and the distribution of the surplus; the composition and role of the standard commodity; the limitations of the distinction between the two types of goods and theconcept of standard commodity and the supposed impossibility of constructing the standard commodity.

  3. Entrapment in phospholipid vesicles quenches photoactivity of quantum dots

    Directory of Open Access Journals (Sweden)

    Generalov R

    2011-09-01

    Full Text Available Roman Generalov1,2, Simona Kavaliauskiene1, Sara Westrøm1, Wei Chen3, Solveig Kristensen2, Petras Juzenas11Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway; 2School of Pharmacy, University of Oslo, Oslo, Norway; 3Department of Physics, The University of Texas at Arlington, Arlington, TX, USAAbstract: Quantum dots have emerged with great promise for biological applications as fluorescent markers for immunostaining, labels for intracellular trafficking, and photosensitizers for photodynamic therapy. However, upon entry into a cell, quantum dots are trapped and their fluorescence is quenched in endocytic vesicles such as endosomes and lysosomes. In this study, the photophysical properties of quantum dots were investigated in liposomes as an in vitro vesicle model. Entrapment of quantum dots in liposomes decreases their fluorescence lifetime and intensity. Generation of free radicals by liposomal quantum dots is inhibited compared to that of free quantum dots. Nevertheless, quantum dot fluorescence lifetime and intensity increases due to photolysis of liposomes during irradiation. In addition, protein adsorption on the quantum dot surface and the acidic environment of vesicles also lead to quenching of quantum dot fluorescence, which reappears during irradiation. In conclusion, the in vitro model of phospholipid vesicles has demonstrated that those quantum dots that are fated to be entrapped in endocytic vesicles lose their fluorescence and ability to act as photosensitizers.Keywords: fluorescence lifetime, free radicals, liposomes, lipodots, reactive oxygen species

  4. Entrapment in phospholipid vesicles quenches photoactivity of quantum dots.

    Science.gov (United States)

    Generalov, Roman; Kavaliauskiene, Simona; Westrøm, Sara; Chen, Wei; Kristensen, Solveig; Juzenas, Petras

    2011-01-01

    Quantum dots have emerged with great promise for biological applications as fluorescent markers for immunostaining, labels for intracellular trafficking, and photosensitizers for photodynamic therapy. However, upon entry into a cell, quantum dots are trapped and their fluorescence is quenched in endocytic vesicles such as endosomes and lysosomes. In this study, the photophysical properties of quantum dots were investigated in liposomes as an in vitro vesicle model. Entrapment of quantum dots in liposomes decreases their fluorescence lifetime and intensity. Generation of free radicals by liposomal quantum dots is inhibited compared to that of free quantum dots. Nevertheless, quantum dot fluorescence lifetime and intensity increases due to photolysis of liposomes during irradiation. In addition, protein adsorption on the quantum dot surface and the acidic environment of vesicles also lead to quenching of quantum dot fluorescence, which reappears during irradiation. In conclusion, the in vitro model of phospholipid vesicles has demonstrated that those quantum dots that are fated to be entrapped in endocytic vesicles lose their fluorescence and ability to act as photosensitizers.

  5. Studies of silicon quantum dots prepared at different substrate temperatures

    Science.gov (United States)

    Al-Agel, Faisal A.; Suleiman, Jamal; Khan, Shamshad A.

    2017-03-01

    In this research work, we have synthesized silicon quantum dots at different substrate temperatures 193, 153 and 123 K at a fixed working pressure 5 Torr. of Argon gas. The structural studies of these silicon quantum dots have been undertaken using X-ray diffraction, Field Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopy (HRTEM). The optical and electrical properties have been studied using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Fluorescence spectroscopy and I-V measurement system. X-ray diffraction pattern of Si quantum dots prepared at different temperatures show the amorphous nature except for the quantum dots synthesized at 193 K which shows polycrystalline nature. FESEM images of samples suggest that the size of quantum dots varies from 2 to 8 nm. On the basis of UV-visible spectroscopy measurements, a direct band gap has been observed for Si quantum dots. FTIR spectra suggest that as-grown Si quantum dots are partially oxidized which is due exposure of as-prepared samples to air after taking out from the chamber. PL spectra of the synthesized silicon quantum dots show an intense peak at 444 nm, which may be attributed to the formation of Si quantum dots. Temperature dependence of dc conductivity suggests that the dc conductivity enhances exponentially by raising the temperature. On the basis above properties i.e. direct band gap, high absorption coefficient and high conductivity, these silicon quantum dots will be useful for the fabrication of solar cells.

  6. Los bienes de interés cultural de Gáldar (Canarias y el conjunto histórico “Plaza de Santiago” (1981-2006

    Directory of Open Access Journals (Sweden)

    Juan Sebastián López García

    2013-10-01

    Full Text Available En 1981, hace veinticinco años, la zona central de Gáldar fue declarada “Conjunto Histórico Artístico” con la denominación de Plaza de Santiago. Sin embargo no era el primer bien cultural que obtenía una distinción de este tipo, ya que Gáldar había sido pionera en 1949 con el yacimiento de El Agujero y La Guancha, primero de los de carácter arqueológico declarado en Canarias, al que seguiría en 1972 la Cueva Pintada. Hasta la década de los setenta prevalecieron los bienes arqueológicos, situación que se modificó en las dos últimas décadas del siglo XX después del reconocimiento de la Plaza de Santiago y su entorno. Junto con edificaciones religiosas también se incluyeron ejemplos de arquitectura doméstica, completándose con algunos yacimientos prehispánicos. Una particular circunstancia fue la declaración en 1993 del pago de Barranco Hondo de Abajo, lo que convertía a Gáldar en el primer municipio de Canarias que contaba con dos conjuntos históricos, siendo éste a la vez el primero de la comunidad autonóma con características rurales. De la relación de los declarados, si exceptuamos la mayoría de los de carácter arqueológico, buena parte son urbanos. Una característica es que se incluyen categorías variadas, incluyendo la existencia de una zona arqueológica junto a un conjunto histórico y varios monumentos (de arquitectura religiosa y doméstica. Este hecho es lógico si se tiene en cuenta la particularidad de Gáldar y su condición de núcleo histórico de superposición.Twenty five years ago, in 1981, the central zone of Galdar was declared an "Historic Artistic Site" with the name of Plaza de Santiago. But this was not the first cultural asset to obtain a distinction of this kind, as Galdar pioneered protection of this kind with the El Agujero and La Guancha site, the first archaeological site declared in the Canary Islands, followed by La Cueva Pintada, in 1972. Archaeological assets prevailed up

  7. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

    KAUST Repository

    Sun, Liangfeng

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

  8. Honor femenino y economía de bienes simbólicos en Maracaibo, Venezuela, a finales del siglo XIX (1880 – 1900

    Directory of Open Access Journals (Sweden)

    Luis Rincón Rubio

    2008-05-01

    Full Text Available Se presenta en este trabajo una aproximación antropológica a las representaciones culturales del honor femenino circulantes en la ciudad de Maracaibo, Venezuela, a finales del siglo XIX. La investigación realizada adopta un enfoque teórico-metodológico de corte estructuralista-constructivista, abordando el orden social como un sistema simbólico organizado según una lógica de la diferencia y partiendo de la premisa de que prácticas y representaciones están orientadas externamente por las estructuras objetivas de la sociedad, e internamente por esquemas de percepción, pensamiento y acción de origen social. Al tratarse de un trabajo de antropología histórica, los informantes fueron sustituidos por fuentes documentales ubicadas en diferentes archivos venezolanos. Se encuentra que las representaciones culturales del honor femenino en la sociedad en cuestión asociaban este concepto con la castidad sexual, reproduciendo esquemas culturales vigentes en la órbita del mundo occidental y proporcionando una lógica para el mantenimiento de relaciones desiguales de género y poder en la vida pública y privada de los marabinos. El capital social y el capital simbólico habrían sido componentes fundamentales del capital total de que se disponía entonces en la lucha cotidiana por la obtención de recursos y por el reconocimiento social, en una economía de bienes simbólicos que atribuía al parecer preferentemente a los hombres el trabajo oficial de conservación o incremento de dichas formas de capital.

  9. La evolución de las exportaciones de bienes de China: una visión panarómica = Chinese goods exports development: An overview

    Directory of Open Access Journals (Sweden)

    Ana Salvador Chamorro

    2013-12-01

    Full Text Available El proceso de reforma económica que ha experimentado la economía de China es uno de los fenómenos de mayor relevancia en la evolución de la Economía Mundial en los últimos treinta años y, sin duda, seguirá siéndolo en el futuro. Dentro de este proceso, la apertura al exterior, que el gobierno chino inició en 1978, ha situado al país en un lugar de máxima relevancia dentro de los flujos comerciales y financieros internacionales. En este contexto, el objetivo de este trabajo es intentar realizar un análisis general de la evolución del comercio exterior de China en las últimas décadas, prestando especial atención a sus exportaciones de bienes y poniendo énfasis en los cambios experimentados durante los últimos años.The process of economic reform that has experienced the Chinese economy is one of the most important events in the evolution of the World Economy in the past 30 years, and will undoubtedly remain so in the future. Within this economic reform, the opening process that the Chinese Government began in 1978, has put the country in a place of utmost importance in the international trade and financial flows. In this context, this paper try to perform an analysis of the evolution of China's foreign trade in recent decades, with particular attention to its exports and emphasizing the changes in recent years

  10. EL BESTIARIO DEL HISTORIADOR: LAS BIOGRAFÍAS DE "MONSTRUOS" DE BENJAMÍN VICUÑA MACKENNA Y LA IDENTIDAD LIBERAL COMO UN BIEN EN DISPUTA

    Directory of Open Access Journals (Sweden)

    Manuel Vicuña

    2008-06-01

    Full Text Available Este trabajo identifica y analiza una conjunto heterogéneo de textos (libros, artículos de prensa, folletos, diarios personales del historiador Benjamín Vicuña Mackenna, los cuales, si bien aluden a temáticas muy diversas, conforman una constelación de sentido marcada por el esfuerzo de apropiación de la identidad liberal, definida no en función de las disputas ideológicas con la Iglesia Católica y el Partido Conservador, sino con relación a la lucha por la libertad electoral y el ensanchamiento de la base de ejercicio de la soberanía popular, cualquiera fuera el signo político del gobierno en ejercicio. Para ello, indaga en obras de distintos periodos del historiador, así como en variados episodios de su biografía, con el propósito de contextualizar las circunstancias de producción de los textos de interés para el análisis.This article identifies and analyzes a heterogeneous body of texts (books, press articles, pamphlets and personal diaries authored by Chilean historian Benjamín Vicuña Mackenna. These texts form part of a single constellation of meaning characterized by the effort of appropriation of a liberal identity, although they concern different subjects and were intended for diverse readerships. This identity was not defined based on the disputes with the Catholic Church or by the Conservative Party. Instead identity was defined by taking into account the fight for electoral freedom and the democratizing effects of popular sovereignty. The article explores the works of Vicuña Mackenna and various episodes of his life to contextualize the circumstances of the texts analyzed.

  11. Composición de los hogares y niveles de gastos en bienes y servicios básicos en el departamento del cauca, Colombia

    Directory of Open Access Journals (Sweden)

    Andrés Mauricio Gómez Sánchez

    2016-03-01

    Full Text Available Éste documento tiene como objetivo caracterizar los hogares rurales y urbanos del departamento del Cauca, Colombia y clasificarlos según la tipología y el ciclo de vida del hogar, para establecer su relación con los niveles de gasto mínimo en bienes básicos, es decir, con los que definen los umbrales críticos de pobreza. Para tal efecto, se utiliza la Encuesta de Calidad de Vida de 2011 y se estiman modelos de análisis de varianza multifactoriales. Los resultados muestran, entre otros, que el tipo de hogar más frecuente, tanto en el área rural como la urbana, es el nuclear con hijos y los gastos mínimos básicos, en general, son en alimentos, vivienda y salud. Los rubros de educación y transporte presentan niveles más altos de consumo en los hogares urbanos que en los rurales. The main objective of this paper is to describe the rural and urban households of the Cauca department in Colombia. The idea is to classify the households according to their typology and household life cycle in order to establish their relation with the minimum levels of expenditure on basic goods, this means with the ones that define the critical poverty thresholds. For this end, the 2011 Quality of Life survey is used as well as multifactorial variance analysis. The results show that the most common type of household for both rural and urban areas is the nuclear type of household with children, showing usually a minimal basic expenditure on food, housing and health. Education and transportation present higher consump-tion levels at urban households.

  12. La evolución de las exportaciones de bienes de China: una visión panarómica = Chinese goods exports development: An overview

    Directory of Open Access Journals (Sweden)

    Ana Salvador Chamorro

    2014-07-01

    Full Text Available Resumen El proceso de reforma económica que ha experimentado la economía de China es uno de los fenómenos de mayor relevancia en la evolución de la Economía Mundial en los últimos treinta años y, sin duda, seguirá siéndolo en el futuro. Dentro de este proceso, la apertura al exterior, que el gobierno chino inició en 1978, ha situado al país en un lugar de máxima relevancia dentro de los flujos comerciales y financieros internacionales. En este contexto, el objetivo de este trabajo es intentar realizar un análisis general de la evolución del comercio exterior de China en las últimas décadas, prestando especial atención a sus exportaciones de bienes y poniendo énfasis en los cambios experimentados durante los últimos años. Abstract The process of economic reform that has experienced the Chinese economy is one of the most important events in the evolution of the World Economy in the past 30 years, and will undoubtedly remain so in the future. Within this economic reform, the opening process that the Chinese Government began in 1978, has put the country in a place of utmost importance in the international trade and financial flows. In this context, this paper try to perform an analysis of the evolution of China's foreign trade in recent decades, with particular attention to its exports and emphasizing the changes in recent years.

  13. Nanobeam photonic crystal cavity quantum dot laser

    CERN Document Server

    Gong, Yiyang; Shambat, Gary; Sarmiento, Tomas; Harris, James S; Vuckovic, Jelena

    2010-01-01

    The lasing behavior of one dimensional GaAs nanobeam cavities with embedded InAs quantum dots is studied at room temperature. Lasing is observed throughout the quantum dot PL spectrum, and the wavelength dependence of the threshold is calculated. We study the cavity lasers under both 780 nm and 980 nm pump, finding thresholds as low as 0.3 uW and 19 uW for the two pump wavelengths, respectively. Finally, the nanobeam cavity laser wavelengths are tuned by up to 7 nm by employing a fiber taper in near proximity to the cavities. The fiber taper is used both to efficiently pump the cavity and collect the cavity emission.

  14. Efficient Luminescence from Perovskite Quantum Dot Solids

    KAUST Repository

    Kim, Younghoon

    2015-11-18

    © 2015 American Chemical Society. Nanocrystals of CsPbX3 perovskites are promising materials for light-emitting optoelectronics because of their colloidal stability, optically tunable bandgap, bright photoluminescence, and excellent photoluminescence quantum yield. Despite their promise, nanocrystal-only films of CsPbX3 perovskites have not yet been fabricated; instead, highly insulating polymers have been relied upon to compensate for nanocrystals\\' unstable surfaces. We develop solution chemistry that enables single-step casting of perovskite nanocrystal films and overcomes problems in both perovskite quantum dot purification and film fabrication. Centrifugally cast films retain bright photoluminescence and achieve dense and homogeneous morphologies. The new materials offer a platform for optoelectronic applications of perovskite quantum dot solids.

  15. Mesoscopic Cavity Quantum Electrodynamics with Quantum Dots

    CERN Document Server

    Childress, L I; Lukin, M D

    2003-01-01

    We describe an electrodynamic mechanism for coherent, quantum mechanical coupling between spacially separated quantum dots on a microchip. The technique is based on capacitive interactions between the electron charge and a superconducting transmission line resonator, and is closely related to atomic cavity quantum electrodynamics. We investigate several potential applications of this technique which have varying degrees of complexity. In particular, we demonstrate that this mechanism allows design and investigation of an on-chip double-dot microscopic maser. Moreover, the interaction may be extended to couple spatially separated electron spin states while only virtually populating fast-decaying superpositions of charge states. This represents an effective, controllable long-range interaction, which may facilitate implementation of quantum information processing with electron spin qubits and potentially allow coupling to other quantum systems such as atomic or superconducting qubits.

  16. Energy level statistics of quantum dots.

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Woods Halley, J

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  17. Design of tunneling injection quantum dot lasers

    Institute of Scientific and Technical Information of China (English)

    JIA Guo-zhi; YAO Jiang-hong; SHU Yong-chun; WANG Zhan-guo

    2007-01-01

    To implement high quality tunneling injection quantum dot lasers,effects of primary factors on performance of the tunneling injection quantum dot lasers were investigated. The considered factors were tunneling probability,tunneling time and carriers thermal escape time from the quantum well. The calculation results show that with increasing of the ground-state energy level in quantum well,the tunneling probability increases and the tunneling time decreases,while the thermal escape time decreases because the ground-state energy levelis shallower. Longitudinal optical phonon-assisted tunneling can be an effective method to solve the problem that both the tunneling time and the thermal escape time decrease simultaneously with the ground-state energy level increasing in quantum well.

  18. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    R K Pandey; Manoj K Harbola; V Ranjan; Vijay A Singh

    2003-01-01

    Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as ‘artificial atoms’ by some, they are much larger (1 100 nm) than real atoms. One can study a variety of manyelectron effects in them, which are otherwise difficult to observe in a real atom. We have treated these effects within the local density approximation (LDA) and the Harbola–Sahni (HS) scheme. HS is free of the selfinteraction error of the LDA. Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of the size and shape dependence of the level spacing. Scaling laws for the Hubbard ‘’ are established.

  19. Energy level statistics of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tsau, C-Y [University of Wisconsin-Madison, Madison, WI 53706 (United States); Nghiem, Diu [University of Wisconsin-Madison, Madison, WI 53706 (United States); Joynt, Robert [University of Wisconsin-Madison, Madison, WI 53706 (United States); Halley, J Woods [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  20. Energy level statistics of quantum dots

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Halley, J. Woods

    2007-05-01

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  1. Light emission from Si quantum dots

    Directory of Open Access Journals (Sweden)

    Philippe M. Fauchet

    2005-01-01

    Full Text Available Si quantum dots (QDs as small as ∼2 nm in diameter have been synthesized by a variety of techniques. Because of quantum confinement and the elimination of bulk or surface defects, these dots can emit light from the near infrared throughout the visible with quantum efficiencies in excess of 10%. The luminescence wavelength range has been extended to longer wavelengths by the addition of light-emitting rare earths such as erbium (Er. Light-emitting devices (LEDs have been fabricated and their performances are starting to approach those of direct band gap semiconductor or organic LEDs. A search for a Si QD-based laser is even under way. The state-of-the-art in the materials science, physics, and device development of luminescent Si QDs is reviewed and areas of future research are pointed out.

  2. Peptide-Decorated Tunable-Fluorescence Graphene Quantum Dots.

    Science.gov (United States)

    Sapkota, Bedanga; Benabbas, Abdelkrim; Lin, Hao-Yu Greg; Liang, Wentao; Champion, Paul; Wanunu, Meni

    2017-03-22

    We report here the synthesis of graphene quantum dots with tunable size, surface chemistry, and fluorescence properties. In the size regime 15-35 nm, these quantum dots maintain strong visible light fluorescence (mean quantum yield of 0.64) and a high two-photon absorption (TPA) cross section (6500 Göppert-Mayer units). Furthermore, through noncovalent tailoring of the chemistry of these quantum dots, we obtain water-stable quantum dots. For example, quantum dots with lysine groups bind strongly to DNA in solution and inhibit polymerase-based DNA strand synthesis. Finally, by virtue of their mesoscopic size, the quantum dots exhibit good cell permeability into living epithelial cells, but they do not enter the cell nucleus.

  3. Single quantum dots fundamentals, applications, and new concepts

    CERN Document Server

    2003-01-01

    This book reviews recent advances in the exciting and rapid growing field of semiconductor quantum dots by contributions from some of the most prominent researchers in the field. Special focus is given to the optical and electronic properties of single quantum dots due to their potential applications in devices operating with single electrons and/or single photons. This includes quantum dots in electric and magnetic fields, cavity-quantum electrodynamics, nonclassical light generation, and coherent optical control of excitons. Single Quantum Dots also addresses various growth techniques as well as potential device applications such as quantum dot lasers, and new concepts like a single-photon source, and a single quantum dot laser.

  4. Principles of conjugating quantum dots to proteins via carbodiimide chemistry.

    Science.gov (United States)

    Song, Fayi; Chan, Warren C W

    2011-12-09

    The covalent coupling of nanomaterials to bio-recognition molecules is a critical intermediate step in using nanomaterials for biology and medicine. Here we investigate the carbodiimide-mediated conjugation of fluorescent quantum dots to different proteins (e.g., immunoglobulin G, bovine serum albumin, and horseradish peroxidase). To enable these studies, we developed a simple method to isolate quantum dot bioconjugates from unconjugated quantum dots. The results show that the reactant concentrations and protein type will impact the overall number of proteins conjugated onto the surfaces of the quantum dots, homogeneity of the protein-quantum dot conjugate population, quantum efficiency, binding avidity, and enzymatic kinetics. We propose general principles that should be followed for the successful coupling of proteins to quantum dots.

  5. Mode Competition in Dual-Mode Quantum Dots Semiconductor Microlaser

    CERN Document Server

    Chusseau, Laurent; Viktorovitch, P; Letartre, Xavier

    2013-01-01

    This paper describes the modeling of quantum dots lasers with the aim of assessing the conditions for stable cw dual-mode operation when the mode separation lies in the THz range. Several possible models suited for InAs quantum dots in InP barriers are analytically evaluated, in particular quantum dots electrically coupled through a direct exchange of excitation by the wetting layer or quantum dots optically coupled through the homogeneous broadening of their optical gain. A stable dual-mode regime is shown possible in all cases when quantum dots are used as active layer whereas a gain medium of quantum well or bulk type inevitably leads to bistable behavior. The choice of a quantum dots gain medium perfectly matched the production of dual-mode lasers devoted to THz generation by photomixing.

  6. Quantum Dots and Their Multimodal Applications: A Review

    Directory of Open Access Journals (Sweden)

    Paul H. Holloway

    2010-03-01

    Full Text Available Semiconducting quantum dots, whose particle sizes are in the nanometer range, have very unusual properties. The quantum dots have band gaps that depend in a complicated fashion upon a number of factors, described in the article. Processing-structure-properties-performance relationships are reviewed for compound semiconducting quantum dots. Various methods for synthesizing these quantum dots are discussed, as well as their resulting properties. Quantum states and confinement of their excitons may shift their optical absorption and emission energies. Such effects are important for tuning their luminescence stimulated by photons (photoluminescence or electric field (electroluminescence. In this article, decoupling of quantum effects on excitation and emission are described, along with the use of quantum dots as sensitizers in phosphors. In addition, we reviewed the multimodal applications of quantum dots, including in electroluminescence device, solar cell and biological imaging.

  7. Templated self-assembly of SiGe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dais, Christian

    2009-08-19

    This PhD thesis reports on the fabrication and characterization of exact aligned SiGe quantum dot structures. In general, SiGe quantum dots which nucleate via the Stranski-Krastanov growth mode exhibit broad size dispersion and nucleate randomly on the surface. However, to tap the full potential of SiGe quantum dots it is necessary to control the positioning and size of the dots on a nanometer length, e.g. for electronically addressing of individual dots. This can be realized by so-called templated self-assembly, which combines top-down lithography with bottom-up selfassembly. In this process the lithographically defined pits serve as pre-defined nucleation points for the epitaxially grown quantum dots. In this thesis, extreme ultraviolet interference lithography at a wavelength of e=13.4 nm is employed for prepatterning of the Si substrates. This technique allows the precise and fast fabrication of high-resolution templates with a high degree of reproducibility. The subsequent epitaxial deposition is either performed by molecular beam epitaxy or low-pressure chemical vapour deposition. It is shown that the dot nucleation on pre-patterned substrates depends strongly on the lithography parameters, e.g. size and periodicity of the pits, as well as on the epitaxy parameters, e.g. growth temperature or material coverage. The interrelations are carefully analyzed by means of scanning force microscopy, transmission electron microscopy and X-ray diffraction measurements. Provided that correct template and overgrowth parameters are chosen, perfectly aligned and uniform SiGe quantum dot arrays of different period, size as well as symmetry are created. In particular, the quantum dot arrays with the so far smallest period (35 nm) and smallest size dispersion are fabricated in this thesis. Furthermore, the strain fields of the underlying quantum dots allow the fabrication of vertically aligned quantum dot stacks. Combining lateral and vertical dot alignment results in three

  8. Ac response of a coupled double quantum dot

    Institute of Scientific and Technical Information of China (English)

    Xu Jie; W.Z. Shangguan; Zhan Shi-Chang

    2005-01-01

    The effect of phase-breaking process on the ac response of a coupled double quantum dot is studied in this paper based on the nonequilibrium Green function formalism. A general expression is derived for the ac current in the presence of electron-phonon interaction. The ac conductance is numerically computed and the results are compared with those in [Anatram M P and Datts S 1995 Phys. Rev. B 51 7632]. Our results reveal that the inter-dot electron tunnelling interplays with that between dots and electron reservoirs, and contributes prominently to the ac current when inter-dot tunnelling coupling is much larger than the tunnelling coupling between dots and electron reservoirs. In addition, the phase-breaking process is found to have a significant effect on the ac transport through the coupled double dot.

  9. Electric and Magnetic Interaction between Quantum Dots and Light

    DEFF Research Database (Denmark)

    Tighineanu, Petru

    a future challenge for the droplet-epitaxy technique. A multipolar theory of spontaneous emission from quantum dots is developed to explain the recent observation that In(Ga)As quantum dots break the dipole theory. The analysis yields a large mesoscopic moment, which contains magnetic-dipole and electric......-matter interaction of both electric and magnetic character. Our study demonstrates that In(Ga)As quantum dots lack parity symmetry and, as consequence, can be employed for locally probing the parity symmetry of complex photonic nanostructures. This opens the prospect for interfacing quantum dots with optical......The present thesis reports research on the optical properties of quantum dots by developing new theories and conducting optical measurements. We demonstrate experimentally singlephoton superradiance in interface-uctuation quantum dots by recording the temporal decay dynamics in conjunction...

  10. DLTS measurements on GaSb/GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hoegner, Annika; Nowozin, Tobias; Marent, Andreas; Bimberg, Dieter [Institut fuer Festkoerperphysik, TU Berlin (Germany); Tseng, Chi-Che [Institute of Photonics Technologies, NTHU (China); Lin, Shih-Yen [Institute of Optoelectronic Sciences, NTOU (China)

    2010-07-01

    Memory devices based on hole storage in self-organized quantum dots offer significant advantages with respect to storage time and scalability. Recently, we demonstrated a first prototype based on InAs/GaAs quantum dots at low temperatures. To enable feasible storage times at room temperature the localisation energy of the quantum dots has to be increased by using other material systems. A first step in this direction is the use of GaSb quantum dots within a GaAs matrix. We have characterized self-organized GaSb/GaAs quantum dots embedded into a n{sup +}p-diode structure. DLTS measurements on hole emission were conducted and yield a strong peak from which a mean emission energy of about 400 meV can be extracted. The reference sample without the quantum dots (containing only the wetting layer) shows no such peak.

  11. Quantum dot spectroscopy using a single phosphorus donor

    Science.gov (United States)

    Büch, Holger; Fuechsle, Martin; Baker, William; House, Matthew G.; Simmons, Michelle Y.

    2015-12-01

    Using a deterministic single P donor placed with atomic precision accuracy next to a nanoscale silicon quantum dot, we present a way to analyze the energy spectrum of small quantum dots in silicon by tunnel-coupled transport measurements. The energy-level structure of the quantum dot is observed as resonance features within the transport bias triangles when the donor chemical potential is aligned with states within the quantum dot as confirmed by a numeric rate equation solver SIMON. This technique allows us to independently extract the quantum dot level structure irrespective of the density of states in the leads. Such a method is useful for the investigation of silicon quantum dots in the few-electron regime where the level structure is governed by an intricate interplay between the spin- and the valley-orbit degrees of freedom.

  12. The Silicon:Colloidal Quantum Dot Heterojunction

    KAUST Repository

    Masala, Silvia

    2015-10-13

    A heterojunction between crystalline silicon and colloidal quantum dots (CQDs) is realized. A special interface modification is developed to overcome an inherent energetic band mismatch between the two semiconductors, and realize the efficient collection of infrared photocarriers generated in the CQD film. This junction is used to produce a sensitive near infrared photodetector. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Depleted Bulk Heterojunction Colloidal Quantum Dot Photovoltaics

    KAUST Repository

    Barkhouse, D. Aaron R.

    2011-05-26

    The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows for high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar devices. A record power conversion of 5.5% under simulated AM 1.5 illumination conditions is reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Pharmaceutical and biomedical applications of quantum dots.

    Science.gov (United States)

    Bajwa, Neha; Mehra, Neelesh K; Jain, Keerti; Jain, Narendra K

    2016-05-01

    Quantum dots (QDs) have captured the fascination and attention of scientists due to their simultaneous targeting and imaging potential in drug delivery, in pharmaceutical and biomedical applications. In the present study, we have exhaustively reviewed various aspects of QDs, highlighting their pharmaceutical and biomedical applications, pharmacology, interactions, and toxicological manifestations. The eventual use of QDs is to dramatically improve clinical diagnostic tests for early detection of cancer. In recent years, QDs were introduced to cell biology as an alternative fluorescent probe.

  15. Depleted bulk heterojunction colloidal quantum dot photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Barkhouse, D.A.R. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); IBM Thomas J. Watson Research Center, Kitchawan Road, Yorktown Heights, NY, 10598 (United States); Debnath, Ratan; Kramer, Illan J.; Zhitomirsky, David; Levina, Larissa; Sargent, Edward H. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Pattantyus-Abraham, Andras G. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Quantum Solar Power Corporation, 1055 W. Hastings, Ste. 300, Vancouver, BC, V6E 2E9 (Canada); Etgar, Lioz; Graetzel, Michael [Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Swiss Federal Institute of Technology, CH-1015 Lausanne (Switzerland)

    2011-07-26

    The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows for high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar devices. A record power conversion of 5.5% under simulated AM 1.5 illumination conditions is reported. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Barrier Engineered Quantum Dot Infrared Photodetectors

    Science.gov (United States)

    2015-06-01

    Advisor, Space Based Advanced Sensing and Protection //SIGNED// JOHN BEAUCHEMIN Chief Engineer, Spacecraft Technology Division Space Vehicles...QD based device can be further improved by planting the dots into a CE DWELL structure to reduce the operating bias while maintaining good...noteworthy low operating bias voltage indicates its feasibility for fabrication of FPA using commercially available silicon read-out circuits. Figure 3. (a

  17. Quantum-dot excitons in nanostructured environments

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Stobbe, Søren; Lodahl, Peter

    2011-01-01

    The interaction between light and quantum-dot (QD) excitons is strongly influenced by the environment in which the QD is placed. We have investigated the interaction by measuring the time-resolved spontaneous-emission rate of QD excitons in different nanostructured environments. Thereby, we have...... is demonstrated and the influence of disorder is discussed. The findings have a strong bearing on future nanophotonic devices....

  18. Quantum-dot excitons in nanostructured environments

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Stobbe, Søren; Lodahl, Peter

    2010-01-01

    The interaction between light and quantum-dot (QD) excitons is strongly influenced by the environment in which the QD is placed. We have investigated the interaction by measuring the time-resolved spontaneous-emission rate of QD excitons in different nanostructured environments. Thereby, we have...... is demonstrated and the influence of disorder is discussed. The findings have a strong bearing on future nanophotonic devices....

  19. The pinning effect in quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Monisha, P. J., E-mail: pjmonisha@gmail.com [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Mukhopadhyay, Soma [Department of Physics, D V R College of Engineering and Technology, Hyderabad-502285 (India)

    2014-04-24

    The pinning effect is studied in a Gaussian quantum dot using the improved Wigner-Brillouin perturbation theory (IWBPT) in the presence of electron-phonon interaction. The electron ground state plus one phonon state is degenerate with the electron in the first excited state. The electron-phonon interaction lifts the degeneracy and the first excited states get pinned to the ground state plus one phonon state as we increase the confinement frequency.

  20. Local Gate Control of a Carbon Nanotube Double Quantum Dot

    Science.gov (United States)

    2016-04-04

    Nanotube Double Quantum Dot N. Mason,*† M. J. Biercuk,* C. M. Marcus† We have measured carbon nanotube quantum dots with multiple electro- static gates and...used the resulting enhanced control to investigate a nano- tube double quantum dot. Transport measurements reveal honeycomb charge stability diagrams...This ability to control electron interactions in the quantum regime in a molecular conductor is important for applications such as quantum

  1. Gates controlled parallel-coupled bilayer graphene double quantum dot

    CERN Document Server

    Wang, Lin-Jun; Wei, Da; Cao, Gang; Tu, Tao; Xiao, Ming; Guo, Guang-Can; Chang, A M

    2011-01-01

    Here we report the fabrication and quantum transport measurements of gates controlled parallel-coupled bilayer graphene double quantum dot. It is shown that the interdot coupling strength of the parallel double dots can be effectively tuned from weak to strong regime by both the in-plane plunger gates and back gate. All the relevant energy scales and parameters of the bilayer graphene parallel-coupled double dot can be extracted from the honeycomb charge stability diagrams revealed through the transport measurements.

  2. Electron States of Few-Electron Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    戴振宏; 孙金祚; 张立德; 李作宏; 黄士勇; 隋鹏飞

    2002-01-01

    We study few-electron semiconductor quantum dots using the unrestricted Hartree-Fock-Roothaan method based on the Gaussian basis. Our emphasis is on the energy level calculation for quantum dots. The confinement potential in a quantum dot is assumed to be in a form of three-dimensional spherical finite potential well. Some valuable results, such as the rearrangement of the energy level, have been obtained.

  3. Aerial measurement error with a dot planimeter: Some experimental estimates

    Science.gov (United States)

    Yuill, R. S.

    1971-01-01

    A shape analysis is presented which utilizes a computer to simulate a multiplicity of dot grids mathematically. Results indicate that the number of dots placed over an area to be measured provides the entire correlation with accuracy of measurement, the indices of shape being of little significance. Equations and graphs are provided from which the average expected error, and the maximum range of error, for various numbers of dot points can be read.

  4. Local Quantum Dot Tuning on Photonic Crystal Chips

    CERN Document Server

    Faraon, Andrei; Fushman, Ilya; Stoltz, Nick; Petroff, Pierre; Vuckovic, Jelena

    2007-01-01

    Quantum networks based on InGaAs quantum dots embedded in photonic crystal devices rely on QDs being in resonance with each other and with the cavities they are embedded in. We developed a new technique based on temperature tuning to spectrally align different quantum dots located on the same chip. The technique allows for up to 1.8nm reversible on-chip quantum dot tuning.

  5. Exciton lifetime measurements on single silicon quantum dots.

    Science.gov (United States)

    Sangghaleh, Fatemeh; Bruhn, Benjamin; Schmidt, Torsten; Linnros, Jan

    2013-06-01

    We measured the exciton lifetime of single silicon quantum dots, fabricated by electron beam lithography, reactive ion etching and oxidation. The observed photoluminescence decays are of mono-exponential character with a large variation (5-45 μs) from dot to dot, even for the same emission energy. We show that this lifetime variation may be the origin of the heavily debated non-exponential (stretched) decays typically observed for ensemble measurements.

  6. Recent advances in carbon-based dots for electroanalysis.

    Science.gov (United States)

    Yulong, Ying; Xinsheng, Peng

    2016-04-25

    Carbon-based dots represent a new type of quantum dot with unique and well-defined properties owing to their quantum confinement and edge effects, which are widely employed in sensing, light-emitting diodes, nanomedicine, photocatalysis, electrocatalysis, bioimaging, etc. In this review, we update the latest research results of carbon-based dots in this rapidly evolving field of electroanalysis, place emphases on their applications as sensors and give future perspectives for developing more smart sensors.

  7. Production and targeting of monovalent quantum dots.

    Science.gov (United States)

    Seo, Daeha; Farlow, Justin; Southard, Kade; Jun, Young-Wook; Gartner, Zev J

    2014-10-23

    The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in biology, where clustering and the spatial organization of biomolecules is often the object of study. We describe here a protocol to produce monovalent quantum dots (mQDs) that can be accomplished in most biological research laboratories via a simple mixing of CdSe/ZnS core/shell QDs with phosphorothioate DNA (ptDNA) of defined length. After a single ptDNA strand has wrapped the QD, additional strands are excluded from the surface. Production of mQDs in this manner can be accomplished at small and large scale, with commercial reagents, and in minimal steps. These mQDs can be specifically directed to biological targets by hybridization to a complementary single stranded targeting DNA. We demonstrate the use of these mQDs as imaging probes by labeling SNAP-tagged Notch receptors on live mammalian cells, targeted by mQDs bearing a benzylguanine moiety.

  8. Interference and interactions in open quantum dots

    CERN Document Server

    Bird, J P; Ferry, D K; Moura, A P S; Lai, Y C; Indlekofer, K M

    2003-01-01

    In this report, we review the results of our joint experimental and theoretical studies of electron-interference, and interaction, phenomena in open electron cavities known as quantum dots. The transport through these structures is shown to be heavily influenced by the remnants of their discrete density of states, elements of which remain resolved in spite of the strong coupling that exists between the cavity and its reservoirs. The experimental signatures of this density of states are discussed at length in this report, and are shown to be related to characteristic wavefunction scarring, involving a small number of classical orbits. A semiclassical analysis of this behaviour shows it to be related to the effect of dynamical tunnelling, in which electrons are injected into the dot tunnel through classically forbidden regions of phase space, to access isolated regular orbits. The dynamical tunnelling gives rise to the formation of long-lived quasi-bound states in the open dots, and the many-body implications a...

  9. Probing relaxation times in graphene quantum dots

    Science.gov (United States)

    Volk, Christian; Neumann, Christoph; Kazarski, Sebastian; Fringes, Stefan; Engels, Stephan; Haupt, Federica; Müller, André; Stampfer, Christoph

    2013-01-01

    Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Here we report pulsed-gate transient current spectroscopy and relaxation time measurements of excited states in graphene quantum dots. This is achieved by an advanced device design that allows to individually tune the tunnelling barriers down to the low megahertz regime, while monitoring their asymmetry. Measuring transient currents through electronic excited states, we estimate a lower bound for charge relaxation times on the order of 60–100 ns. PMID:23612294

  10. Nonrenewal statistics in transport through quantum dots

    Science.gov (United States)

    Ptaszyński, Krzysztof

    2017-01-01

    The distribution of waiting times between successive tunneling events is an already established method to characterize current fluctuations in mesoscopic systems. Here, I investigate mechanisms generating correlations between subsequent waiting times in two model systems, a pair of capacitively coupled quantum dots and a single-level dot attached to spin-polarized leads. Waiting time correlations are shown to give insight into the internal dynamics of the system; for example they allow distinction between different mechanisms of the noise enhancement. Moreover, the presence of correlations breaks the validity of the renewal theory. This increases the number of independent cumulants of current fluctuation statistics, thus providing additional sources of information about the transport mechanism. I also propose a method for inferring the presence of waiting time correlations based on low-order current correlation functions. This method gives a way to extend the analysis of nonrenewal current fluctuations to the systems for which single-electron counting is not experimentally feasible. The experimental relevance of the findings is also discussed; for example reanalysis of previous results concerning transport in quantum dots is suggested.

  11. Thermoelectric study of dissipative quantum-dot heat engines

    Science.gov (United States)

    De, Bitan; Muralidharan, Bhaskaran

    2016-10-01

    This paper examines the thermoelectric response of a dissipative quantum-dot heat engine based on the Anderson-Holstein model in two relevant operating limits, (i) when the dot phonon modes are out of equilibrium, and (ii) when the dot phonon modes are strongly coupled to a heat bath. In the first case, a detailed analysis of the physics related to the interplay between the quantum-dot level quantization, the on-site Coulomb interaction, and the electron-phonon coupling on the thermoelectric performance reveals that an n -type heat engine performs better than a p -type heat engine. In the second case, with the aid of the dot temperature estimated by incorporating a thermometer bath, it is shown that the dot temperature deviates from the bath temperature as electron-phonon interaction in the dot becomes stronger. Consequently, it is demonstrated that the dot temperature controls the direction of phonon heat currents, thereby influencing the thermoelectric performance. Finally, the conditions on the maximum efficiency with varying phonon couplings between the dot and all the other macroscopic bodies are analyzed in order to reveal the nature of the optimum junction.

  12. Highly fluorescent xerogels with entrapped carbon dots for organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Quaranta, A., E-mail: quaranta@ing.unitn.it [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Carturan, S. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Campagnaro, A.; Dalla Palma, M. [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Giarola, M.; Daldosso, N. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy); Maggioni, G. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Mariotto, G. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy)

    2014-02-28

    Organically modified silicate thin film and bulk samples were prepared using [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMOS) as precursor with the addition of different amounts of AEAP-TMOS functionalized C-dots, prepared by reaction of AEAP-TMOS and citric acid at high temperature. The synthesis of surface functionalized C-dots was followed by Fourier Transform Infrared (FTIR) spectroscopy, and the C-dots optical properties were characterized by optical absorption and UV–vis fluorescence. Thin xerogel films and bulk samples were studied by FTIR, Raman and fluorescence spectroscopy. Intense blue-green emission was observed by UV excitation of functionalized C-dots. Carbon quantum dot (CQD) luminescence was preserved also in the xerogel matrices, and the energy transfer from the matrix to CQDs, which is a key characteristic for scintillation detectors, was investigated in the two systems. - Highlights: • Functionalized carbon dots were synthesized. • Carbon dots were dispersed in hybrid xerogel bulk and thin film. • Carbon dots exhibit a strong tunable blue luminescence. • Xerogels were characterized by FT-IR, Raman and fluorescence spectroscopies. • Energy transfer processes were evidenced between C-dots and xerogel matrix.

  13. Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    See, Gloria G. [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, Illinois 61801 (United States); Xu, Lu; Nuzzo, Ralph G. [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); Sutanto, Erick; Alleyne, Andrew G. [Mechanical Science and Engineering Department, University of Illinois at Urbana-Champaign, 154 Mechanical Engineering Building, Urbana, Illinois 61801 (United States); Cunningham, Brian T. [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, Illinois 61801 (United States); Department of Bioengineering, University of Illinois at Urbana-Champaign, 1270 Digital Computer Laboratory, MC-278, Urbana, Illinois 61801 (United States)

    2015-08-03

    Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the quantum dot material than application through drop-casting or spin coating. In addition, the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, which enables an 8× output enhancement and highly polarized emission from the photonic crystal structure.

  14. Multicolor Nitrogen-Doped Carbon Dots for Live Cell Imaging.

    Science.gov (United States)

    Du, Fengyi; Li, Jianan; Hua, Ye; Zhang, Miaomiao; Zhou, Zhou; Yuan, Jing; Wang, Jun; Peng, Wanxin; Zhang, Li; Xia, Sheng; Wang, Dongqing; Yang, Shiming; Xu, Wenrong; Gong, Aihua; Shao, Qixiang

    2015-05-01

    Doping carbon dots with nitrogen atoms considerably enhances their fluorescence properties. However, the mechanism by which the carbon dots are doped is not fully understood. We developed a facile bottom-up hydrothermal carbonization (HTC) process that uses glucose and glycine as precursors for the synthesis of photoluminescent nitrogen-doped carbon dots. The as-prepared nitrogen-doped carbon dots were mono-dispersed spherical particles with a diameter of -2.8 nm. The doped nitrogen atoms assumed pyridinic type and pyrrolic type configurations to participate in the nanocrystal structure of the carbon dots. It appeared that the nitrogen doping introduces a new internal structure. The aqueous solution of nitrogen-doped carbon dots showed excitation wavelength-dependent multicolor photoluminescence. Further, these nitrogen-doped carbon dots readily entered the cytoplasm of A549 cancer cells and showed no significant cytotoxicity. The internalized nitrogen-doped carbon dots were localized to the cell membrane and cytoplasm, particularly around the nucleus. Further, the as-prepared, biocompatible, nitrogen-doped carbon dots demonstrated the potential to be used as fluorescent probes for multicolor live cell labeling, tracking, and imaging.

  15. An Exciton Bound to a Neutral Donor in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    解文方

    2002-01-01

    The binding energies for an exciton (X) trapped in a two-dimensional quantum dot by a neutral donor have been calculated using the method of few-body physics for the heavy hole (σ= 0.196) and the light hole (σr = 0.707).We find that the (D0, X) complex confined in a quantum dot has in general a larger binding energy than those in a two-dimensional quantum well and a three-dimensional bulk semiconductor, and the binding energy increases with the decrease of the dot radius. At dot radius R →∞, we compare our calculated result with the previous results.

  16. Nonequilibrium Electron Transport Through a Quantum Dot from Kubo Formula

    Institute of Scientific and Technical Information of China (English)

    L(U) Rong; ZHANG Guang-Ming

    2005-01-01

    Based on the Kubo formula for an electron tunneling junction, we revisit the nonequilibrium transport properties through a quantum dot. Since the Fermi level of the quantum dot is set by the conduction electrons of the leads, we calculate the electron current from the left side by assuming the quantum dot coupled to the right lead as another side of the tunneling junction, and the other way round is used to calculate the current from the right side. By symmetrizing these two currents, an effective local density states on the dot can be obtained, and is discussed at high and low temperatures, respectively.

  17. Synthesis of CdSe Quantum Dots Using Fusarium oxysporum

    OpenAIRE

    Takaaki Yamaguchi; Yoshijiro Tsuruda; Tomohiro Furukawa; Lumi Negishi; Yuki Imura; Shohei Sakuda; Etsuro Yoshimura; Michio Suzuki

    2016-01-01

    CdSe quantum dots are often used in industry as fluorescent materials. In this study, CdSe quantum dots were synthesized using Fusarium oxysporum. The cadmium and selenium concentration, pH, and temperature for the culture of F. oxysporum (Fusarium oxysporum) were optimized for the synthesis, and the CdSe quantum dots obtained from the mycelial cells of F. oxysporum were observed by transmission electron microscopy. Ultra-thin sections of F. oxysporum showed that the CdSe quantum dots were pr...

  18. Advanced Architecture for Colloidal PbS Quantum Dot Solar Cells Exploiting a CdSe Quantum Dot Buffer Layer.

    Science.gov (United States)

    Zhao, Tianshuo; Goodwin, Earl D; Guo, Jiacen; Wang, Han; Diroll, Benjamin T; Murray, Christopher B; Kagan, Cherie R

    2016-09-22

    Advanced architectures are required to further improve the performance of colloidal PbS heterojunction quantum dot solar cells. Here, we introduce a CdI2-treated CdSe quantum dot buffer layer at the junction between ZnO nanoparticles and PbS quantum dots in the solar cells. We exploit the surface- and size-tunable electronic properties of the CdSe quantum dots to optimize its carrier concentration and energy band alignment in the heterojunction. We combine optical, electrical, and analytical measurements to show that the CdSe quantum dot buffer layer suppresses interface recombination and contributes additional photogenerated carriers, increasing the open-circuit voltage and short-circuit current of PbS quantum dot solar cells, leading to a 25% increase in solar power conversion efficiency.

  19. Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xiao; Wang, Hao; Yi, Qinghua; Wang, Yun; Cong, Shan; Zhao, Jie; Sun, Yinghui; Zou, Guifu, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Qian, Zhicheng [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, Jianwen; Xiong, Jie, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Hongmei [Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2015-11-16

    Due to the different emission mechanism between fluorescent carbon dots and semiconductor quantum dots (QDs), it is of interest to explore the potential emission in hetero-structured carbon dots/semiconducting QDs. Herein, we design carbon dots coated CdTe QDs (CDQDs) and investigate their inherent emission. We demonstrate switchable emission for the hetero-interactions of the CDQDs. Optical analyses indicate electron transfer between the carbon dots and the CdTe QDs. A heterojunction electron process is proposed as the driving mechanism based on N atom protonation of the carbon dots. This work advances our understanding of the interaction mechanism of the heterostructured CDQDs and benefits the future development of optoelectronic nanodevices with new functionalities.

  20. The Electron-Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIEWen-Fang; ZHUWu

    2003-01-01

    The energy spectra of low-lying states of an exciton in a single and a vertically coupled quantum dots are studied under the influence of a perpendicularly applied magnetic field. Calculations are made by using the method of numerical diagonalization of the Hamiltonian within the effective-mass approximation. We also calculated the binding energy of the ground and the excited states of an exciton in a single quantum dot and that in a vertically coupled quantum dot as a function of the dot radius for different vaJues of the distance and the magnetic field strength.

  1. The Electron-Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang; ZHU Wu

    2003-01-01

    The energy spectra of low-lying states of an exciton in a single and a vertically coupled quantum dots arestudied under the influence of a perpendicularly applied magnetic field. Calculations are made by using the method ofnumerical diagonalization of the Hamiltonian within the effective-mass approximation. We also calculated the bindingenergy of the ground and the excited states of an exciton in a single quantum dot and that in a vertically coupledquantum dot as a function of the dot radius for different values of the distance and the magnetic field strength.

  2. The Effectiveness of Family-Based DOTS versus Professional-Family Mix DOTS in Treating Smears Positive Tuberculosis

    Directory of Open Access Journals (Sweden)

    Hassan Yekrang Sis

    2014-07-01

    Full Text Available Background: The present study compared the effectiveness of Family-Based DOTS (FB-DOTS versus Professional-Family Mix DOTS (PFM-DOTS in smear positive tuberculosis (TB patients. Methods: This semi-experimental study was performed in Tuberculosis and Lung Diseases Research Center of Tabriz in 2011-2012, among 57 TB patients recruited into either FB-DOTS or PFM-DOTS groups. At the baseline of the study, knowledge of both patients and their supervisors were assessed while at the end point, smear and culture of sputum, quality of life, knowledge and satisfaction of the patients along with the knowledge and satisfaction of their super-visors were assessed. Results: The difference for sputum smear negative (culture was 16.2 (4.8% and 7.7(6.9% for the PFM-DOTS in comparison with FB DOTS by the end of the second and forth months of treatment, respectively. A significant difference was observed between the two groups in relation to knowledge, satisfaction (patients and supervisors and all four domains of quality of life: physical health (P=0.036, psychological health (P<0.001, social relations (P=0.026 and environmental health (P<0.001. Conclusion: The PFM-DOTS treatment strategy in which health experts follow the patients in their homes seems to be among most appropriate strategies in treating TB.

  3. El caso del embargo y los bienes fuera del comercio en la enseñanza del derecho en Colombia. ¿Un caso de ceguera por atención?

    Directory of Open Access Journals (Sweden)

    Carlos A. Delvasto P.

    2013-01-01

    Full Text Available Gran parte de la educación legal de Colombia por décadas ha enseñado que el embargo saca los bienes fuera del comercio, al punto que esta falsa asociación ha creado un punto ciego en la cultura legal. Ahora bien, pero y ¿qué determina la existencia de puntos ciegos y facilita la transmisión de falsas asociaciones? Bueno, en mi opinión, una respuesta para tener en mente es la manera como se enseña derecho en Colombia, pues si el profesor utiliza la cátedra magistral como metodología de enseñanza y tiene un sesgo conceptual, la probabilidad de detectar este se limita por fenómenos cognitivos como el caso de la ceguera por atención.

  4. Tunnel-coupled quantum dots: Atomistic Theory of Quantum Dot Molecules and Arrays

    Science.gov (United States)

    Bryant, Garnett W.; Aizpurua, J.; Jaskolski, W.; Zielinski, Michal

    2003-03-01

    Quantum dots are studied as artificial atoms for building novel artificial solids, as nanodevices in nanoelectronics, and as bio/nanohybrids. We present an atomistic tight-binding theory of coupled CdS nanocrystals and vertically and laterally coupled InAs self-assembled dots. Electron states of coupled dots follow the analogy of coupled dots as artificial molecules. Symmetric/antisymmetric pairs are formed with strongest coupling between states with high density at interdot interfaces. Complex coupling of hole states, with significant departures from the artificial molecule analogy, occurs because the coupling is determined by the hole envelope function and the hole atomic state. Some hole states couple to form symmetric/antisymmetric pairs. Other hole states couple through additional intermediate states to form two strongly split symmetric states and an antisymmetric state insensitive to coupling. These coupling effects lead to level reordering, changes in state symmetry, conversion of dark states to bright states and vice versa, and tailored polarization dependence.

  5. Fast synthesize ZnO quantum dots via ultrasonic method.

    Science.gov (United States)

    Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-05-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots.

  6. Single-photon superradiance from a quantum dot

    DEFF Research Database (Denmark)

    Tighineanu, Petru; Daveau, Raphaël Sura; Lehmann, Tau Bernstorff

    2016-01-01

    We report on the observation of single-photon superradiance from an exciton in a semiconductor quantum dot. The confinement by the quantum dot is strong enough for it to mimic a two-level atom, yet sufficiently weak to ensure superradiance. The electrostatic interaction between the electron and t...

  7. A Nanowire-Based Plasmonic Quantum Dot Laser.

    Science.gov (United States)

    Ho, Jinfa; Tatebayashi, Jun; Sergent, Sylvain; Fong, Chee Fai; Ota, Yasutomo; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2016-04-13

    Quantum dots enable strong carrier confinement and exhibit a delta-function like density of states, offering significant improvements to laser performance and high-temperature stability when used as a gain medium. However, quantum dot lasers have been limited to photonic cavities that are diffraction-limited and further miniaturization to meet the demands of nanophotonic-electronic integration applications is challenging based on existing designs. Here we introduce the first quantum dot-based plasmonic laser to reduce the cross-sectional area of nanowire quantum dot lasers below the cutoff limit of photonic modes while maintaining the length in the order of the lasing wavelength. Metal organic chemical vapor deposition grown GaAs-AlGaAs core-shell nanowires containing InGaAs quantum dot stacks are placed directly on a silver film, and lasing was observed from single nanowires originating from the InGaAs quantum dot emission into the low-loss higher order plasmonic mode. Lasing threshold pump fluences as low as ∼120 μJ/cm(2) was observed at 7 K, and lasing was observed up to 125 K. Temperature stability from the quantum dot gain, leading to a high characteristic temperature was demonstrated. These results indicate that high-performance, miniaturized quantum dot lasers can be realized with plasmonics.

  8. Exciton dephasing in single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis;

    2000-01-01

    . The homogeneous and inhomogeneous broadening of InGaAs quantum dot luminescence is of central importance for the potential application of this material system in optoelectronic devices. Recent measurements of MOCVD-grown InAs/InGaAs quantum dots indicate a large homogeneous broadening at room temperature due...

  9. Teaching Beginning Chemistry Students Simple Lewis Dot Structures

    Science.gov (United States)

    Nassiff, Peter; Czerwinski, Wendy A.

    2015-01-01

    Students beginning their initial study of chemistry often have a difficult time mastering simple Lewis dot structures. Textbooks show students how to manipulate Lewis structures by moving valence electron dots around the chemical structure so each atom has an octet or duet. However, an easier method of teaching Lewis structures for simple…

  10. Electron Energy Level Statistics in Graphene Quantum Dots

    NARCIS (Netherlands)

    De Raedt, H.; Katsnellson, M. I.; Katsnelson, M.I.

    2008-01-01

    Motivated by recent experimental observations of size quantization of electron energy levels in graphene quantum dots [7] we investigate the level statistics in the simplest tight-binding model for different dot shapes by computer simulation. The results are in a reasonable agreement with the experi

  11. Imaging vasculature and lymphatic flow in mice using quantum dots

    DEFF Research Database (Denmark)

    Ballou, Byron; Ernst, Lauren A.; Andreko, Susan

    2009-01-01

    Quantum dots are ideal probes for fluorescent imaging of vascular and lymphatic tissues. On injection into appropriate sites, red- and near-infrared-emitting quantum dots provide excellent definition of vasculature, lymphoid organs, and lymph nodes draining both normal tissues and tumors. We deta...

  12. Negative Trions Trapped by a Spherical Parabolic Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, a negatively charged exciton trapped by a spherical parabolic quantum dot has been investigated. The energy spectra of low-lying states are calculated by means of matrix diagonalization. The important feature of the low-lying states of the negatively charged excitons in a spherical quantum dot is obtained via an analysis of the energy spectra.

  13. 49 CFR 41.119 - DOT regulated buildings.

    Science.gov (United States)

    2010-10-01

    ... and additions to existing buildings will ensure that each DOT regulated building is designed and... section pertains to all new building projects for which development of detailed plans and specifications.... (d) For DOT regulated buildings a certification of compliance with the seismic design...

  14. Hybrid passivated colloidal quantum dot solids

    KAUST Repository

    Ip, Alex

    2012-07-29

    Colloidal quantum dot (CQD) films allow large-area solution processing and bandgap tuning through the quantum size effect. However, the high ratio of surface area to volume makes CQD films prone to high trap state densities if surfaces are imperfectly passivated, promoting recombination of charge carriers that is detrimental to device performance. Recent advances have replaced the long insulating ligands that enable colloidal stability following synthesis with shorter organic linkers or halide anions, leading to improved passivation and higher packing densities. Although this substitution has been performed using solid-state ligand exchange, a solution-based approach is preferable because it enables increased control over the balance of charges on the surface of the quantum dot, which is essential for eliminating midgap trap states. Furthermore, the solution-based approach leverages recent progress in metal:chalcogen chemistry in the liquid phase. Here, we quantify the density of midgap trap states in CQD solids and show that the performance of CQD-based photovoltaics is now limited by electrong-"hole recombination due to these states. Next, using density functional theory and optoelectronic device modelling, we show that to improve this performance it is essential to bind a suitable ligand to each potential trap site on the surface of the quantum dot. We then develop a robust hybrid passivation scheme that involves introducing halide anions during the end stages of the synthesis process, which can passivate trap sites that are inaccessible to much larger organic ligands. An organic crosslinking strategy is then used to form the film. Finally, we use our hybrid passivated CQD solid to fabricate a solar cell with a certified efficiency of 7.0%, which is a record for a CQD photovoltaic device. © 2012 Macmillan Publishers Limited. All rights reserved.

  15. Quantum dot density studies for quantum dot intermediate band solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Thomassen, Sedsel Fretheim; Zhou, Dayong; Vitelli, Stefano; Mayani, Maryam Gholami; Fimland, Bjoern-Ove; Reenaas, Turid Worren

    2010-07-01

    Quantum dots (QDs) have been an active area of research for many years and have been implemented in several applications, such as lasers and detectors. During the last years, some attempts have been made to increase the absorption and efficiency of solar cells by inserting QDs into the intrinsic region of pin solar cells. So far, these attempts have been successful in increasing the absorption, but not the cell efficiency. There are probably several reasons for this lack of efficiency increase, but we believe that one important reason is the low density of the implemented QDs. In this work, samples of single layer InAs QDs on n-GaAs(001) substrates have been grown by molecular beam epitaxy (MBE) and we have performed a systematic study of how deposition parameters affect the QD density. The aim is to achieve densities > 1011 cm-2. The nominal substrate temperature (360 - 500 deg. C), the InAs growth rate (0.085 - 1 ML/s) and thickness (2.0 - 2.8 ML) have been varied in a systematic way for two different deposition methods of InAs, i.e. continuous deposition or deposition with interruptions. In addition, we have for the continuous growth samples also varied the As-flux (0.5 - 6 centre dot10-6 torr). Scanning electron microscopy (SEM) has been the main characterization method to determine quantum dot sizes and densities, and atomic force microscopy (AFM) has been used for evaluation of the quantum dot heights. We find that the QD density increases with reduced growth temperature and that it is higher for samples grown continuously than for samples grown with growth interruptions. The homogeneity is also strongly affected by temperature, InAs deposition method and the As-flux. We have observed QD densities as high as 2.5 centre dot1011 cm-2 for the samples grown at the lowest growth temperatures. (Author)

  16. Silicon Quantum Dots for Quantum Information Processing

    Science.gov (United States)

    2013-11-01

    A. J. Ferguson , A. S. Dzurak, and R. G. Clark. Gate-defined quantum dots in intrinsic silicon. Nano Letters, 7(7), 2051 (2007). 4, 21, 44, 68, 99 132...B, 80(7), 075310 (2009). 66 [105] M. Field, C. Smith, M. Pepper , D. Ritchie, J. Frost, G. Jones, and D. Hasko. Measurements of Coulomb blockade with a...transistor as an integrated charge sensor. Applied Physics Letters, 97(26), 262113 (2010). 68, 74 [111] G. Podd, S. Angus, D. Williams, and A. Ferguson

  17. Graphene Quantum Dots for Theranostics and Bioimaging.

    Science.gov (United States)

    Schroeder, Kathryn L; Goreham, Renee V; Nann, Thomas

    2016-10-01

    Since their advent in the early 1990s, nanomaterials hold promise to constitute improved technologies in the biomedical area. In particular, graphene quantum dots (GQDs) were conjectured to produce new or improve current methods used for bioimaging, drug delivery, and biomarker sensors for early detection of diseases. This review article critically compares and discusses current state-of-the-art use of GQDs in biology and health sciences. It shows the ability of GQDs to be easily functionalised for use as a targeted multimodal treatment and imaging platform. The in vitro and in vivo toxicity of GQDs are explored showing low toxicity for many types of GQDs.

  18. Resonance fluorescence from a telecom-wavelength quantum dot

    CERN Document Server

    Al-Khuzheyri, R; Huwer, J; Santana, T S; Szymanska, J Skiba-; Felle, M; Ward, M B; Stevenson, R M; Farrer, I; Tanner, M G; Hadfield, R H; Ritchie, D A; Shields, A J; Gerardot, B D

    2016-01-01

    We report on resonance fluorescence from a single quantum dot emitting at telecom wavelengths. We perform high-resolution spectroscopy and observe the Mollow triplet in the Rabi regime--a hallmark of resonance fluorescence. The measured resonance-fluorescence spectra allow us to rule out pure dephasing as a significant decoherence mechanism in these quantum dots. Combined with numerical simulations, the experimental results provide robust characterisation of charge noise in the environment of the quantum dot. Resonant control of the quantum dot opens up new possibilities for on-demand generation of indistinguishable single photons at telecom wavelengths as well as quantum optics experiments and direct manipulation of solid-state qubits in telecom-wavelength quantum dots.

  19. Quantum dots in diagnostics and detection: principles and paradigms.

    Science.gov (United States)

    Pisanic, T R; Zhang, Y; Wang, T H

    2014-06-21

    Quantum dots are semiconductor nanocrystals that exhibit exceptional optical and electrical behaviors not found in their bulk counterparts. Following seminal work in the development of water-soluble quantum dots in the late 1990's, researchers have sought to develop interesting and novel ways of exploiting the extraordinary properties of quantum dots for biomedical applications. Since that time, over 10,000 articles have been published related to the use of quantum dots in biomedicine, many of which regard their use in detection and diagnostic bioassays. This review presents a didactic overview of fundamental physical phenomena associated with quantum dots and paradigm examples of how these phenomena can and have been readily exploited for manifold uses in nanobiotechnology with a specific focus on their implementation in in vitro diagnostic assays and biodetection.

  20. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    Directory of Open Access Journals (Sweden)

    Z. O. Lipatova

    2015-03-01

    Full Text Available Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been found to be dependent on the registration wavelength in the range from 450 to 700 nm. Obtained fluorophosphate glasses with CdS quantum dots can find their application as fluorescent materials with intensive luminescence band and long excited-state natural lifetime.

  1. Single-electron Spin Resonance in a Quadruple Quantum Dot

    Science.gov (United States)

    Otsuka, Tomohiro; Nakajima, Takashi; Delbecq, Matthieu R.; Amaha, Shinichi; Yoneda, Jun; Takeda, Kenta; Allison, Giles; Ito, Takumi; Sugawara, Retsu; Noiri, Akito; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2016-08-01

    Electron spins in semiconductor quantum dots are good candidates of quantum bits for quantum information processing. Basic operations of the qubit have been realized in recent years: initialization, manipulation of single spins, two qubit entanglement operations, and readout. Now it becomes crucial to demonstrate scalability of this architecture by conducting spin operations on a scaled up system. Here, we demonstrate single-electron spin resonance in a quadruple quantum dot. A few-electron quadruple quantum dot is formed within a magnetic field gradient created by a micro-magnet. We oscillate the wave functions of the electrons in the quantum dots by applying microwave voltages and this induces electron spin resonance. The resonance energies of the four quantum dots are slightly different because of the stray field created by the micro-magnet and therefore frequency-resolved addressable control of each electron spin resonance is possible.

  2. Colloidal-quantum-dot spasers and plasmonic amplifiers

    CERN Document Server

    Kress, Stephan J P; Rohner, Patrik; Kim, David K; Antolinez, Felipe V; Zaininger, Karl-Augustin; Jayanti, Sriharsha V; Richner, Patrizia; McPeak, Kevin M; Poulikakos, Dimos; Norris, David J

    2016-01-01

    Colloidal quantum dots are robust, efficient, and tunable emitters now used in lighting, displays, and lasers. Consequently, when the spaser, a laser-like source of surface plasmons, was first proposed, quantum dots were specified as the ideal plasmonic gain medium. Subsequent spaser designs, however, have required a single material to simultaneously provide gain and define the plasmonic cavity, an approach ill-suited to quantum dots and other colloidal nanomaterials. Here we develop a more open architecture that decouples the gain medium from the cavity, leading to a versatile class of quantum-dot-based spasers that allow controlled generation, extraction, and manipulation of plasmons. We first create high-quality-factor, aberration-corrected, Ag plasmonic cavities. We then incorporate quantum dots via electrohydrodynamic printing18,19 or drop-casting. Photoexcitation under ambient conditions generates monochromatic plasmons above threshold. This signal is extracted, directed through an integrated amplifier,...

  3. RKKY interaction in a chirally coupled double quantum dot system

    Energy Technology Data Exchange (ETDEWEB)

    Heine, A. W.; Tutuc, D.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover (Germany); Zwicknagl, G. [Institut für Mathematische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig (Germany); Schuh, D. [Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätstr. 31, 93053 Regensburg (Germany); Wegscheider, W. [Laboratorium für Festkörperphysik, ETH Zürich, Schafmattstr. 16, 8093 Zürich, Switzerland and Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätstr. 31, 93053 Regens (Germany)

    2013-12-04

    The competition between the Kondo effect and the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction is investigated in a double quantum dots system, coupled via a central open conducting region. A perpendicular magnetic field induces the formation of Landau Levels which in turn give rise to the so-called Kondo chessboard pattern in the transport through the quantum dots. The two quantum dots become therefore chirally coupled via the edge channels formed in the open conducting area. In regions where both quantum dots exhibit Kondo transport the presence of the RKKY exchange interaction is probed by an analysis of the temperature dependence. The thus obtained Kondo temperature of one dot shows an abrupt increase at the onset of Kondo transport in the other, independent of the magnetic field polarity, i.e. edge state chirality in the central region.

  4. Synthesis of biocompatible multicolor luminescent carbon dots for bioimaging applications

    Directory of Open Access Journals (Sweden)

    Nagaprasad Puvvada, B N Prashanth Kumar, Suraj Konar, Himani Kalita, Mahitosh Mandal and Amita Pathak

    2012-01-01

    Full Text Available Water-soluble carbon dots (C-dots were prepared through microwave-assisted pyrolysis of an aqueous solution of dextrin in the presence of sulfuric acid. The C-dots produced showed multicolor luminescence in the entire visible range, without adding any surface-passivating agent. X-ray diffraction and Fourier transform infrared spectroscopy studies revealed the graphitic nature of the carbon and the presence of hydrophilic groups on the surface, respectively. The formation of uniformly distributed C-dots and their luminescent properties were, respectively, revealed from transmission electron microscopy and confocal laser scanning microscopy. The biocompatible nature of C-dots was confirmed by a cytotoxicity assay on MDA-MB-468 cells and their cellular uptake was assessed through a localization study.

  5. Second-harmonic imaging of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;

    2000-01-01

    Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....

  6. Non-blinking quantum dot with a plasmonic nanoshell resonator

    Science.gov (United States)

    Ji, Botao; Giovanelli, Emerson; Habert, Benjamin; Spinicelli, Piernicola; Nasilowski, Michel; Xu, Xiangzhen; Lequeux, Nicolas; Hugonin, Jean-Paul; Marquier, Francois; Greffet, Jean-Jacques; Dubertret, Benoit

    2015-02-01

    Colloidal semiconductor quantum dots are fluorescent nanocrystals exhibiting exceptional optical properties, but their emission intensity strongly depends on their charging state and local environment. This leads to blinking at the single-particle level or even complete fluorescence quenching, and limits the applications of quantum dots as fluorescent particles. Here, we show that a single quantum dot encapsulated in a silica shell coated with a continuous gold nanoshell provides a system with a stable and Poissonian emission at room temperature that is preserved regardless of drastic changes in the local environment. This novel hybrid quantum dot/silica/gold structure behaves as a plasmonic resonator with a strong Purcell factor, in very good agreement with simulations. The gold nanoshell also acts as a shield that protects the quantum dot fluorescence and enhances its resistance to high-power photoexcitation or high-energy electron beams. This plasmonic fluorescent resonator opens the way to a new family of plasmonic nanoemitters with robust optical properties.

  7. Coherent Dynamics of Quantum Dots in Photonic-Crystal Cavities

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg

    deviations. Similar measurements on a quantum dot in a photonic-crystal cavity sow a Rabi splitting on resonance, while time-resolved measurements prove that the system is in the weak coupling regime. Whle tuning the quantum dot through resonance of the high-Q mode we observe a strong and surprisingly...... Successfully model the decay rates with a microscopic model that allows us to for the first time extract the effective phonon density of states, which we can model with bulk phonons. Studies on a quantum dot detuned from a low-Q mode of a photonic-crystal cavity show a high collection efficiency at the first......In this thesis we have performed quantum-electrodynamics experiments on quantum dots embedded in photonic-crystal cavities. We perform a quantitative comparison of the decay dynamics and emission spectra of quantum dots embedded in a micropillar cavity and a photonic-crystal cavity. The light...

  8. Homogeneous linewidth of self-assembled III-V quantum dots observed in single-dot photoluminescence

    DEFF Research Database (Denmark)

    Leosson, K.; Birkedal, Dan; Magnúsdóttir, Ingibjörg;

    2003-01-01

    We report photoluminescence emission from single self-assembled InAlGaAs quantum dots, which is broadened purely by dephasing processes. We observe linewidths as low as 6+/-3@meV at 10K, which agrees with the homogeneous linewidth derived from four-wave mixing experiments. By selecting dots that ...

  9. DotFETs: MOSFETs strained by a Single SiGE dot in a Low-Temperature ELA Technology

    NARCIS (Netherlands)

    Biasotto, C.

    2011-01-01

    The work presented in this thesis was performed in the context of the European Sixth Framework Program FP6 project “Disposable Dot Field Effect Transistor for High Speed Si Integrated Circuits”, referred to as the D-DotFET project. The project had the goal of realizing strain-enhanced mobility in CM

  10. Conflictos por la herencia de bienes vinculados: Mujeres nobles pleiteando Conflicts for the inheritance of linked goods: Noble women going to law

    Directory of Open Access Journals (Sweden)

    Marcela Correa Barboza

    2012-12-01

    Full Text Available La casa, el parentesco, la clientela son vínculos que estructuran a conjuntos de individuos relacionados entre ellos, permitiéndoles actuar como agentes sociales colectivos. En las sociedades alto-modernas, de carácter patriarcal, las mujeres se encontraban supeditadas a la autoridad del varón, siendo éste quien actuaba socialmente, estableciendo diferentes vínculos entre familias, parientes, etc; relaciones a las que las mujeres quedaban sujetas en gran medida. Sin embargo, la historia de las mujeres ha mostrado que ellas tenían un accionar muy activo, eran capaces de intervenir en los vínculos ya existentes de manera decisiva, entablaban alianzas y promovían importantes redes de relaciones, que muchas veces encabezaban. En los últimos veinte años, se han puesto de relieve nuevas fuentes y nuevas categorías que enriquecen los estudios y propician otras formas de mirar la documentación. La utilización de la categoría género en el análisis ha permitido redimensionar el lugar de las mujeres en la historia. En los casos que presentaremos y en los temas que abordaremos, podremos observar las formas en que las mujeres de la muy alta nobleza actúan como verdaderas cabeza de linajes, defendiendo intereses propios, pero sobre todo colectivos - los de su familia-, buscando en los vericuetos legales las formas de conseguir cierto patrimonio, de mantenerlo en su círculo más cercano y, al mismo tiempo, de aumentarlo si consideran la posibilidad de acceder a nuevos bienes a través de herencias, compras, intercambios, etc.The house, kinship, the clientele are links that structure to sets of individuals related to each other, enabling them to act as collective social agents. In high-modern societies, the patriarchal nature, women were subject to male authority, this being who acted socially, establishing links between different families, relatives, etc., relations which women were subject to a great extent. However, women's history has

  11. Cost Effectiveness of DOTS and Non—DOTS Strategies for Smear—Positive Pulmonary Tuberculosis in Beijing

    Institute of Scientific and Technical Information of China (English)

    XU-QUN; JINSHUI-GAO; 等

    2000-01-01

    The cost-effectiveness of DOTS(Directly Observed Treatment,short course)and nonDOTS strategies for smear-positive pulmonary tuberculosis in Beijing was evaluated.Cost calculation was based on the experses of drugs ,chest X-ray films,sputm smears and cultures for the patients.Effectiveness of the intervention was assessed in two aspects:direct benefits to the patients treated and indirect benefits to the others through reduced transmission of tuberculsis;disability adjusted life of year(DALY) was used as an index.The results showed that one DALY could be saved with 45.7 Yuan by DOTS and 471.4 Yuan by non-DOTS.DOTS is a good control strategy for smear-positive tuberculosis.

  12. Cost Effectiveness of DOTS and Non-DOTS Strategies for Smear-positive Pulmonary Tuberculosis in Beijing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The cost-effectiveness of DOTS (Directly Observed Treatment, short course) and non-DOTS strategies for smear-positive pulmonary tuberculosis in Beijing was evaluated. Cost calculation was based on the expenses of drugs, chest X-ray films, sputum smears and cultures for the patients. Effectiveness of the intervention was assessed in two aspects: direct benefits to the patients treated and indirect benefits to the others through reduced transmission of tuberculosis; disability adjusted life of year (DALY) was used as an index. The results showed that one DALY could be saved with 45.7 Yuan by DOTS and 471.4 Yuan by non-DOTS. DOTS is a good control strategy for smear-positive tuberculosis.

  13. Electrons, holes, and excitons in superlattice of cylindrical quantum dots with weakest coupling of quasiparticles between quantum dots layers

    CERN Document Server

    Tkach, N V; Zegrya, G G

    2002-01-01

    The theoretical investigation of the spectrum of electrons, holes, and excitons in the superlattice of cylindrical quantum dots with weakest coupling of quasiparticles between vertical layers of quantum dots is carried out. The calculations are fulfilled by the example of cylindrical quantum dots of beta-HgS introduced into beta-CdS as the superlattice. It is shown that electron and hole in such system form quasi-two-dimensional energy minibands, but excitons are described by the Sugano-Shinada model. The dependence of quasiparticle spectra on geometric parameters of the superlattice with cylindrical quantum dots is studied. It is shown that the position of minibands of all quasiparticles is very sensitive to variation of the quantum dot height

  14. Eléments traces dans le sérum des enfants malnutris et bien nourris vivants à Lubumbashi et Kawama dans un contexte d'un environnement de pollution minière

    Science.gov (United States)

    Musimwa, Aimée Mudekereza; Kanteng, Gray Wakamb; Kitoko, Hermann Tamubango; Luboya, Oscar Numbi

    2016-01-01

    Introduction La place des éléments traces métalliques essentiels en nutrition humaine ne peut plus être ignorée. Les déficits d'apports, les carences secondaires souvent sous – estimées, et les carences iatrogènes font le lit de pathologies telles que les infections et autres. D'où leurs dosages ont une importance particulière pour en évaluer la gravité et faciliter une prise en charge précoce ou améliorer le régime alimentaire. Cette étude a eu pour objectif de déterminer le profil sanguin en éléments traces (cuivre, sélénium, zinc, fer, chrome, cobalt, etc) chez les enfants malnutris et biens nourris dans un milieu minier à Lubumbashi. Méthodes Trois cents onze cas ont été colligés, 182 malnutris et 129 biens nourris, dans une étude descriptive transversale, effectuée de juillet 2013 à décembre 2014. Pour lequel un échantillonnage exhaustif a été réalisé. Le dosage des métaux dans le sérum s'est fait à l’ ICP-OES (spectrométrie de masse à plasma gon induit) au laboratoire de l'Office Congolais de Contrôle de Lubumbashi. Résultats Les oligoéléments essentiels (cuivre, zinc, sélénium et fer) se retrouvent à des concentrations très basses chez les enfants malnutris comme chez les biens nourris. L'arsenic, le cadmium, le magnésium et le manganèse se présentent à des concentrations normales par rapport aux valeurs de références chez les enfants biens nourris. L'antimoine, le chrome, le plomb et le cobalt se retrouvent élevés chez les malnutris et biens nourris. Le nickel est normal chez les malnutris et les biens nourris. Le magnésium, manganèse se sont présentés à des taux très bas chez les enfants malnutris. Conclusion Les enfants malnutris et biens nourris présentent une malnutrition aux oligo-éléments essentiels associés aux éléments traces métalliques. Ce qui permet de supposer qu'une carence en micronutriments essentiel favorise l'absorption des métaux lourds. PMID:27583075

  15. Colloidal Quantum Dot Photovoltaics: A Path Forward

    KAUST Repository

    Kramer, Illan J.

    2011-11-22

    Colloidal quantum dots (CQDs) offer a path toward high-efficiency photovoltaics based on low-cost materials and processes. Spectral tunability via the quantum size effect facilitates absorption of specific wavelengths from across the sun\\'s broad spectrum. CQD materials\\' ease of processing derives from their synthesis, storage, and processing in solution. Rapid advances have brought colloidal quantum dot photovoltaic solar power conversion efficiencies of 6% in the latest reports. These achievements represent important first steps toward commercially compelling performance. Here we review advances in device architecture and materials science. We diagnose the principal phenomenon-electronic states within the CQD film band gap that limit both current and voltage in devices-that must be cured for CQD PV devices to fulfill their promise. We close with a prescription, expressed as bounds on the density and energy of electronic states within the CQD film band gap, that should allow device efficiencies to rise to those required for the future of the solar energy field. © 2011 American Chemical Society.

  16. Colloidal quantum dot light-emitting devices

    Directory of Open Access Journals (Sweden)

    Vanessa Wood

    2010-07-01

    Full Text Available Colloidal quantum dot light-emitting devices (QD-LEDs have generated considerable interest for applications such as thin film displays with improved color saturation and white lighting with a high color rendering index (CRI. We review the key advantages of using quantum dots (QDs in display and lighting applications, including their color purity, solution processability, and stability. After highlighting the main developments in QD-LED technology in the past 15 years, we describe the three mechanisms for exciting QDs – optical excitation, Förster energy transfer, and direct charge injection – that have been leveraged to create QD-LEDs. We outline the challenges facing QD-LED development, such as QD charging and QD luminescence quenching in QD thin films. We describe how optical downconversion schemes have enabled researchers to overcome these challenges and develop commercial lighting products that incorporate QDs to achieve desirable color temperature and a high CRI while maintaining efficiencies comparable to inorganic white LEDs (>65 lumens per Watt. We conclude by discussing some current directions in QD research that focus on achieving higher efficiency and air-stable QD-LEDs using electrical excitation of the luminescent QDs.

  17. Quantum Computer Using Coupled Quantum Dot Molecules

    CERN Document Server

    Wu, N J; Natori, A; Yasunaga, H; Wu*, Nan-Jian

    1999-01-01

    We propose a method for implementation of a quantum computer using artificial molecules. The artificial molecule consists of two coupled quantum dots stacked along z direction and one single electron. One-qubit and two-qubit gates are constructed by one molecule and two coupled molecules, respectively.The ground state and the first excited state of the molecule are used to encode the |0> and |1> states of a qubit. The qubit is manipulated by a resonant electromagnetic wave that is applied directly to the qubit through a microstrip line. The coupling between two qubits in a quantum controlled NOT gate is switched on (off) by floating (grounding) the metal film electrodes. We study the operations of the gates by using a box-shaped quantum dot model and numerically solving a time-dependent Schridinger equation, and demonstrate that the quantum gates can perform the quantum computation. The operating speed of the gates is about one operation per 4ps. The reading operation of the output of the quantum computer can...

  18. Application of Quantum Dots in Biological Imaging

    Directory of Open Access Journals (Sweden)

    Shan Jin

    2011-01-01

    Full Text Available Quantum dots (QDs are a group of semiconducting nanomaterials with unique optical and electronic properties. They have distinct advantages over traditional fluorescent organic dyes in chemical and biological studies in terms of tunable emission spectra, signal brightness, photostability, and so forth. Currently, the major type of QDs is the heavy metal-containing II-IV, IV-VI, or III-V QDs. Silicon QDs and conjugated polymer dots have also been developed in order to lower the potential toxicity of the fluorescent probes for biological applications. Aqueous solubility is the common problem for all types of QDs when they are employed in the biological researches, such as in vitro and in vivo imaging. To circumvent this problem, ligand exchange and polymer coating are proven to be effective, besides synthesizing QDs in aqueous solutions directly. However, toxicity is another big concern especially for in vivo studies. Ligand protection and core/shell structure can partly solve this problem. With the rapid development of QDs research, new elements and new morphologies have been introduced to this area to fabricate more safe and efficient QDs for biological applications.

  19. Quantum dot imaging for embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Gambhir Sanjiv S

    2007-10-01

    Full Text Available Abstract Background Semiconductor quantum dots (QDs hold increasing potential for cellular imaging both in vitro and in vivo. In this report, we aimed to evaluate in vivo multiplex imaging of mouse embryonic stem (ES cells labeled with Qtracker delivered quantum dots (QDs. Results Murine embryonic stem (ES cells were labeled with six different QDs using Qtracker. ES cell viability, proliferation, and differentiation were not adversely affected by QDs compared with non-labeled control cells (P = NS. Afterward, labeled ES cells were injected subcutaneously onto the backs of athymic nude mice. These labeled ES cells could be imaged with good contrast with one single excitation wavelength. With the same excitation wavelength, the signal intensity, defined as (total signal-background/exposure time in millisecond was 11 ± 2 for cells labeled with QD 525, 12 ± 9 for QD 565, 176 ± 81 for QD 605, 176 ± 136 for QD 655, 167 ± 104 for QD 705, and 1,713 ± 482 for QD 800. Finally, we have shown that QD 800 offers greater fluorescent intensity than the other QDs tested. Conclusion In summary, this is the first demonstration of in vivo multiplex imaging of mouse ES cells labeled QDs. Upon further improvements, QDs will have a greater potential for tracking stem cells within deep tissues. These results provide a promising tool for imaging stem cell therapy non-invasively in vivo.

  20. Nano-laser on silicon quantum dots

    Science.gov (United States)

    Huang, Wei-Qi; Liu, Shi-Rong; Qin, Chao-Jian; Lü, Quan; Xu, Li

    2011-04-01

    A new conception of nano-laser is proposed in which depending on the size of nano-clusters (silicon quantum dots (QD)), the pumping level of laser can be tuned by the quantum confinement (QC) effect, and the population inversion can be formed between the valence band and the localized states in gap produced from the surface bonds of nano-clusters. Here we report the experimental demonstration of nano-laser on silicon quantum dots fabricated by nanosecond pulse laser. The peaks of stimulated emission are observed at 605 nm and 693 nm. Through the micro-cavity of nano-laser, a full width at half maximum of the peak at 693 nm can reach to 0.5 nm. The theoretical model and the experimental results indicate that it is a necessary condition for setting up nano-laser that the smaller size of QD (d nano-laser will be limited in the range of 1.7-2.3 eV generally due to the position of the localized states in gap, which is in good agreement between the experiments and the theory.

  1. Study of metallothionein-quantum dots interactions.

    Science.gov (United States)

    Tmejova, Katerina; Hynek, David; Kopel, Pavel; Krizkova, Sona; Blazkova, Iva; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene

    2014-05-01

    Nanoparticles have gained increasing interest in medical and in vivo applications. Metallothionein (MT) is well known as a maintainer of metal ions balance in intracellular space. This is due to high affinity of this protein to any reactive species including metals and reactive oxygen species. The purpose of this study was to determine the metallothionein-quantum dots interactions that were investigated by spectral and electrochemical techniques. CuS, CdS, PbS, and CdTe quantum dots (QDs) were analysed. The highest intensity was shown for CdTe, than for CdS measured by fluorescence. These results were supported by statistical analysis and considered as significant. Further, these interactions were analysed using gel electrophoresis, where MT aggregates forming after interactions with QDs were detected. Using differential pulse voltammetry Brdicka reaction, QDs and MT were studied. This method allowed us to confirm spectral results and, moreover, to observe the changes in MT structure causing new voltammetric peaks called X and Y, which enhanced with the prolonged time of interaction up to 6 h.

  2. Kondo effects in triangular triple quantum dots

    Science.gov (United States)

    Oguri, Akira; Numata, Takahide; Nisikawa, Yunori; Hewson, A. C.

    2009-03-01

    We study the conductance through a triangular triple quantum dot, which is connected to two noninteracting leads, using the numerical renormalization group (NRG). It is found that the system shows a variety of Kondo effects depending on the filling of the triangle. The SU(4) Kondo effect occurs at half-filling, and a sharp conductance dip due to a phase lapse appears in the gate-voltage dependence. Furthermore, when four electrons occupy the three sites on average, a local S=1 moment, which is caused by the Nagaoka mechanism, is induced along the triangle. The temperature dependence of the entropy and spin susceptibility of the triangle shows that this moment is screened by the conduction electrons via two separate stages at different temperatures. The two-terminal and four-terminal conductances show a clear difference at the gate voltages, where the SU(4) or the S=1 Kondo effects occur[1]. We will also discuss effects of deformations of the triangular configuration, caused by the inhomogeneity in the inter-dot couplings and in the gate voltages. [4pt] [1] T.Numata, Y.Nisikawa, A.Oguri, and A.C.Hewson: arXiv:0808.3496.

  3. Using quantum dot photoluminescence for load detection

    Science.gov (United States)

    Moebius, M.; Martin, J.; Hartwig, M.; Baumann, R. R.; Otto, T.; Gessner, T.

    2016-08-01

    We propose a novel concept for an integrable and flexible sensor capable to visualize mechanical impacts on lightweight structures by quenching the photoluminescence (PL) of CdSe quantum dots. Considering the requirements such as visibility, storage time and high optical contrast of PL quenching with low power consumption, we have investigated a symmetrical and an asymmetrical layer stack consisting of semiconductor organic N,N,N',N'-Tetrakis(3-methylphenyl)-3,3'-dimethylbenzidine (HMTPD) and CdSe quantum dots with elongated CdS shell. Time-resolved series of PL spectra from layer stacks with applied voltages of different polarity and simultaneous observation of power consumption have shown that a variety of mechanisms such as photo-induced charge separation and charge injection, cause PL quenching. However, mechanisms such as screening of external field as well as Auger-assisted charge ejection is working contrary to that. Investigations regarding the influence of illumination revealed that the positive biased asymmetrical layer stack is the preferred sensor configuration, due to a charge carrier injection at voltages of 10 V without the need of coincident illumination.

  4. Polymersomes containing quantum dots for cellular imaging

    Directory of Open Access Journals (Sweden)

    Camblin M

    2014-05-01

    Full Text Available Marine Camblin,1 Pascal Detampel,1 Helene Kettiger,1 Dalin Wu,2 Vimalkumar Balasubramanian,1,* Jörg Huwyler1,*1Division of Pharmaceutical Technology, 2Department of Chemistry, University of Basel, Basel, Switzerland*These authors contributed equally to this workAbstract: Quantum dots (QDs are highly fluorescent and stable probes for cellular and molecular imaging. However, poor intracellular delivery, stability, and toxicity of QDs in biological compartments hamper their use in cellular imaging. To overcome these limitations, we developed a simple and effective method to load QDs into polymersomes (Ps made of poly(dimethylsiloxane-poly(2-methyloxazoline (PDMS-PMOXA diblock copolymers without compromising the characteristics of the QDs. These Ps showed no cellular toxicity and QDs were successfully incorporated into the aqueous compartment of the Ps as confirmed by transmission electron microscopy, fluorescence spectroscopy, and fluorescence correlation spectroscopy. Ps containing QDs showed colloidal stability over a period of 6 weeks if stored in phosphate-buffered saline (PBS at physiological pH (7.4. Efficient intracellular delivery of Ps containing QDs was achieved in human liver carcinoma cells (HepG2 and was visualized by confocal laser scanning microscopy (CLSM. Ps containing QDs showed a time- and concentration-dependent uptake in HepG2 cells and exhibited better intracellular stability than liposomes. Our results suggest that Ps containing QDs can be used as nanoprobes for cellular imaging.Keywords: quantum dots, polymersomes, cellular imaging, cellular uptake

  5. Using quantum dot photoluminescence for load detection

    Directory of Open Access Journals (Sweden)

    M. Moebius

    2016-08-01

    Full Text Available We propose a novel concept for an integrable and flexible sensor capable to visualize mechanical impacts on lightweight structures by quenching the photoluminescence (PL of CdSe quantum dots. Considering the requirements such as visibility, storage time and high optical contrast of PL quenching with low power consumption, we have investigated a symmetrical and an asymmetrical layer stack consisting of semiconductor organic N,N,N′,N′-Tetrakis(3-methylphenyl-3,3′-dimethylbenzidine (HMTPD and CdSe quantum dots with elongated CdS shell. Time-resolved series of PL spectra from layer stacks with applied voltages of different polarity and simultaneous observation of power consumption have shown that a variety of mechanisms such as photo-induced charge separation and charge injection, cause PL quenching. However, mechanisms such as screening of external field as well as Auger-assisted charge ejection is working contrary to that. Investigations regarding the influence of illumination revealed that the positive biased asymmetrical layer stack is the preferred sensor configuration, due to a charge carrier injection at voltages of 10 V without the need of coincident illumination.

  6. Ultrashort Dynamics in Quantum Dot Waveguides: Theoretical Analysis and Experimental Investigations

    DEFF Research Database (Denmark)

    Gehrig, E.; Poel, Mike van der; Birkedal, Dan;

    2004-01-01

    Experimental pump-probe measurements and computational modeling on the basis of spatially resolved Quantum Dot Maxwell-Bloch equations allow identification of the processes underlying the ultrafast dot dynamics.......Experimental pump-probe measurements and computational modeling on the basis of spatially resolved Quantum Dot Maxwell-Bloch equations allow identification of the processes underlying the ultrafast dot dynamics....

  7. Highly tuneable hole quantum dots in Ge-Si core-shell nanowires

    Science.gov (United States)

    Brauns, Matthias; Ridderbos, Joost; Li, Ang; van der Wiel, Wilfred G.; Bakkers, Erik P. A. M.; Zwanenburg, Floris A.

    2016-10-01

    We define single quantum dots of lengths varying from 60 nm up to nearly half a micron in Ge-Si core-shell nanowires. The charging energies scale inversely with the quantum dot length between 18 and 4 meV. Subsequently, we split up a long dot into a double quantum dot with a separate control over the tunnel couplings and the electrochemical potential of each dot. Both single and double quantum dot configurations prove to be very stable and show excellent control over the electrostatic environment of the dots, making this system a highly versatile platform for spin-based quantum computing.

  8. Electric properties of Ge quantum dot embedded in Si matrix

    Institute of Scientific and Technical Information of China (English)

    MA Xi-ying; SHI Wei-lin

    2005-01-01

    The electric characteristics of Ge quantum dot grown by molecular beam epitaxy in Si matrix were investigated by admittance spectroscopy and deep level transient spectroscopy. The admittance spectroscopy measurements show that the activation energy of 0.341 eV can be considered as the emitting energy of hole from the ground state of the quantum dot. And the capacitance variation with temperature of the sample shows a platform at various frequencies with reverse bias 0.5 V, which indicates that the boundary of space charge region is located at the quantum dot layer where the large confined hole concentration blocks the further extension of space charge region. When the temperature increases from 120 K to 200 K, the holes in the dot emit out completely. The position of the platform shifting with the increase of the applied frequency shows the frequency effects of the charges in the quantum dot. The deep level transient spectroscopy results show that the charge concentration in the Ge quantum dot is a function of the pulse duration and the reverse bias voltage, the activation energy and capture cross-section of hole decrease with the increase of pulse duration due to the Coulomb charging effect. The valence-band offsets of hole in Ge dot obtained by admittance spectroscopy and deep level transient spectroscopy are 0.341 and 0.338 eV, respectively.

  9. Self-assembled InAs/GaAs quantum dots and quantum dot laser

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Systematic study of molecular beam epitaxy-grown self-assembled In(Ga)As/GaAs, InAlAs/AlGaAs/GaAs, and InAs/InAlAs/InP quantum dots (QDs) is demonstrated. By adjusting growth conditions, surprising alignment, preferential elongation, and pronounced sequential coalescence of dots under the specific condition are realized. Room-temperature (RT) continuous-wave (CW) lasing at the wavelength of 960 nm with output power of 1 W is achieved from vertical coupled InAs/GaAs QDs ensemble. The RT threshold current density is 218 A/cm2. An RT CW output power of 0.53 W ensures at least 3 000 h lasing (only drops 0.83 db). This is one of the best results ever reported.

  10. Standardization of the dot enzyme-lynked immunosorbent assay (dot-ELISA for experimental plague

    Directory of Open Access Journals (Sweden)

    Silvia M. L. Montenegro

    1993-03-01

    Full Text Available A dot enzyme linked immunosorbent assay (dot-ELISA was previously developed to detect specific antibodies in rabbits sera immunized against FIA protein obtained from Yersina pestis. This antigen was covalently linked onto the surface of dacron (polyethyleneterephthalate. Here, standard conditions are described for the optimization of this procedure: an amount of 20 ng of FIA protein was fixed onto dacron; anti-rabbit IgG peroxidase conjugate diluted 1:8,000 and 30% non-fat instant milk as blocking substance were used throughout the method. This procedure was compared with that employing nitrocellulose as solid-phase which showed to be more sensitive. However, the method based on dacron did not show false positive reactions against non-immunized rabbits sera at low antigen amount and diluted anti-IgG peroxidase conjugate.

  11. Self-assembled InAs/GaAs quantum dots and quantum dot laser

    Institute of Scientific and Technical Information of China (English)

    王占国; 刘峰奇; 梁基本; 徐波

    2000-01-01

    Systematic study of molecular beam epitaxy-grown self-assembled ln(Ga)As/GaAs, In-AlAs/AlGaAs/GaAs, and InAs/InAIAs/lnP quantum dots (QDs) is demonstrated. By adjusting growth conditions, surprising alignment, preferential elongation, and pronounced sequential coalescence of dots under the specific condition are realized. Room-temperature (RT) continuous-wave (CW) lasing at the wavelength of 960 nm with output power of 1 W is achieved from vertical coupled InAs/GaAs QDs ensemble. The RT threshold current density is 218 A/cm2. An RT CW output power of 0.53 W ensures at least 3 000 h lasing (only drops 0.83 db). This is one of the best results ever reported.

  12. Linewidth broadening of a quantum dot coupled to an off-resonant cavity

    CERN Document Server

    Majumdar, Arka; Kim, Erik; Englund, Dirk; Kim, Hyochul; Petroff, Pierre; Vuckovic, Jelena

    2010-01-01

    We study the coupling between a photonic crystal cavity and an off-resonant quantum dot under resonant excitation of the cavity or the quantum dot. Linewidths of the quantum dot and the cavity as a function of the excitation laser power are measured. We show that the linewidth of the quantum dot, measured by observing the cavity emission, is significantly broadened compared to the theoretical estimate. This indicates additional incoherent coupling between the quantum dot and the cavity.

  13. Charge sensing of a few-donor double quantum dot in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Watson, T. F., E-mail: tfwatson15@gmail.com; Weber, B.; Büch, H.; Fuechsle, M.; Simmons, M. Y., E-mail: michelle.simmons@unsw.edu.au [Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    2015-12-07

    We demonstrate the charge sensing of a few-donor double quantum dot precision placed with atomic resolution scanning tunnelling microscope lithography. We show that a tunnel-coupled single electron transistor (SET) can be used to detect electron transitions on both dots as well as inter-dot transitions. We demonstrate that we can control the tunnel times of the second dot to the SET island by ∼4 orders of magnitude by detuning its energy with respect to the first dot.

  14. Computation of energy states of hydrogenic quantum dot with two-electrons

    Science.gov (United States)

    Yakar, Y.; Özmen, A.; ćakır, B.

    2016-03-01

    In this study we have investigated the electronic structure of the hydrogenic quantum dot with two electrons inside an impenetrable potential surface. The energy eigenvalues and wavefunctions of the ground and excited states of spherical quantum dot have been calculated by using the Quantum Genetic Algorithm (QGA) and Hartree-Fock Roothaan (HFR) method, and the energies are investigated as a function of dot radius. The results show that as dot radius increases, the energy of quantum dot decreases.

  15. UV Nano Lights - Nonlinear Quantum Dot-Plasmon Coupling

    Science.gov (United States)

    2016-06-20

    AFRL-AFOSR-JP-TR-2016-0072 UV Nano-Lights - Nonlinear Quantum Dot-Plasmon Coupling Eric Waclawik QUEENSLAND UNIVERSITY OF TECHNOLOGY Final Report 06...Final 3.  DATES COVERED (From - To)  03 Feb 2014 to 02 Feb 2016 4.  TITLE AND SUBTITLE UV Nano-Lights - Nonlinear Quantum Dot-Plasmon Coupling 5a...SUBJECT TERMS Quantum Dots, Energy Conversion, Up-conversion, Modeling 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES

  16. Quantum Dots Microstructured Optical Fiber for X-Ray Detection

    Science.gov (United States)

    DeHaven, Stan; Williams, Phillip; Burke, Eric

    2015-01-01

    Microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide are presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dot application technique are discussed.

  17. Quantum dots microstructured optical fiber for x-ray detection

    Science.gov (United States)

    DeHaven, S. L.; Williams, P. A.; Burke, E. R.

    2016-02-01

    A novel concept for the detection of x-rays with microstructured optical fibers containing quantum dots scintillation material comprised of zinc sulfide nanocrystals doped with magnesium sulfide is presented. These quantum dots are applied inside the microstructured optical fibers using capillary action. The x-ray photon counts of these fibers are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The results of the fiber light output and associated effects of an acrylate coating and the quantum dots application technique are discussed.

  18. Imaging GABAc Receptors with Ligand-Conjugated Quantum Dots

    Directory of Open Access Journals (Sweden)

    Ian D. Tomlinson

    2007-01-01

    Full Text Available We report a methodology for labeling the GABAc receptor on the surface membrane of intact cells. This work builds upon our earlier work with serotonin-conjugated quantum dots and our studies with PEGylated quantum dots to reduce nonspecific binding. In the current approach, a PEGylated derivative of muscimol was synthesized and attached via an amide linkage to quantum dots coated in an amphiphilic polymer derivative of a modified polyacrylamide. These conjugates were used to image GABAC receptors heterologously expressed in Xenopus laevis oocytes.

  19. Infrared Focal Plane Arrays Based on Semiconductor Quantum Dots

    Science.gov (United States)

    2002-01-01

    studied in the framework of this, including the collaborating researchers in each of them, are detailed below: 1. “Ultra Small InAs/GaInP/ InP Quantum Dots ”: with...of detectors, which will be attached to Si based signal processors. D:\\FINAL REPORT.doc 4 Part 1 Ultra Small InAs/GaInP/ InP Quantum Dots The heights of...an ensemble of self-assembled InAs/GaAs or InAs/ InP quantum dots (QDs) are typically in the range of 10-30 monolayers [1]. Here, we report on InAs

  20. Temperature Studies of Single InP Quantum Dots

    Science.gov (United States)

    1999-06-18

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012858 TITLE: Temperature Studies of Single InP Quantum Dots DISTRIBUTION...34 QWR/QD.07 St Petersburg, Russia, June 14-18, 1999 © 1999 loffe Institute Temperature studies of single InP quantum dots Valdry Zwiller, Mats-Erik...Information on the size and geometry of our self-assembled InP Quantum Dots grown on GamnP lattice matched to GaAs has been published elsewhere -I

  1. Solvothermal synthesis of InP quantum dots.

    Science.gov (United States)

    Nag, Angshuman; Sarma, D D

    2009-09-01

    We report an efficient and fast solvothermal route to prepare highly crystalline monodispersed InP quantum dots. This solvothermal route, not only ensures inert atmosphere, which is strictly required for the synthesis of phase pure InP quantum dots but also allows a reaction temperature as high as 430 degrees C, which is otherwise impossible to achieve using a typical solution chemistry; the higher reaction temperature makes the reaction more facile. This method also has a judicious control over the size of the quantum dots and thus in tuning the bandgap.

  2. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot

    DEFF Research Database (Denmark)

    Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal;

    2016-01-01

    We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offer....... We notice that the emission spectra consist often of two peaks close in energy, which we explain with a comprehensive theory showing that the symmetry of the system plays a crucial role for the hole levels forming hybridized orbitals. Our results state that crystal phase quantum dots have promising...

  3. Emission redistribution from a quantum dot-bowtie nanoantenna

    OpenAIRE

    Regler, A.; Schraml, K.; Lyamkina, A.; Spiegl, M; Müller, K.; Vuckovic, J.; Finley, J. J.; Kaniber, M.

    2016-01-01

    We present a combined experimental and simulation study of a single self-assembled InGaAs quantum dot coupled to a nearby ($\\sim 25nm$) plasmonic antenna. Micro-photoluminescence spectroscopy shows a $\\sim 2.4\\times$ increase of intensity, which is attributed to spatial far-field redistribution of the emission from the quantum dot-antenna system. Power-dependent studies show similar saturation powers of $2.5\\mu W$ for both coupled and uncoupled quantum dot emission in polarization-resolved me...

  4. Electrostatically defined silicon quantum dots with counted antimony donor implants

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M., E-mail: msingh@sandia.gov; Luhman, D. R.; Lilly, M. P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87175 (United States); Pacheco, J. L.; Perry, D.; Garratt, E.; Ten Eyck, G.; Bishop, N. C.; Wendt, J. R.; Manginell, R. P.; Dominguez, J.; Pluym, T.; Bielejec, E.; Carroll, M. S. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2016-02-08

    Deterministic control over the location and number of donors is crucial to donor spin quantum bits (qubits) in semiconductor based quantum computing. In this work, a focused ion beam is used to implant antimony donors in 100 nm × 150 nm windows straddling quantum dots. Ion detectors are integrated next to the quantum dots to sense the implants. The numbers of donors implanted can be counted to a precision of a single ion. In low-temperature transport measurements, regular Coulomb blockade is observed from the quantum dots. Charge offsets indicative of donor ionization are also observed in devices with counted donor implants.

  5. PL Emission and Shape of Silicon Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The calculation results show that the bonding energy and electronic states of silicon quantum dots are different on various curved surfaces, for example, a Si-0-Si bridge bond on curved surface provides the localized levels in band gap and its bonding energy is shallower than that on facet. The red-shifting of PL spectra on smaller silicon quantum dots can be explained by curved surface effect. Experiments demonstrate that silicon quantum dots are activated for emission due to the localized levels provided in curved surface effect.About The Author: Zhong-Mei Huang,Master in Guizhou University.

  6. Magnetic quantum dot in two-dimensional topological insulators

    Science.gov (United States)

    Li, Guo; Zhu, Jia-Lin; Yang, Ning

    2017-03-01

    Magnetic quantum dots in two-dimensional band and topological insulators are studied by solving the modified Dirac model under nonuniform magnetic fields. The Landau levels split into discrete states with certain angular momentum. The states splitting from the zero Landau levels lie in the energy gap for topological insulators but are out of the gap for band insulators. It is found that the ground states oscillate between the spin-up and spin-down states when the magnetic field or the dot size changes. The oscillation manifests itself as changes of sign and strength of charge currents near the dot's edge.

  7. Dielectrophoretic Manipulation and Separation of Microparticles Using Microarray Dot Electrodes

    Directory of Open Access Journals (Sweden)

    Bashar Yafouz

    2014-04-01

    Full Text Available This paper introduces a dielectrophoretic system for the manipulation and separation of microparticles. The system is composed of five layers and utilizes microarray dot electrodes. We validated our system by conducting size-dependent manipulation and separation experiments on 1, 5 and 15 μm polystyrene particles. Our findings confirm the capability of the proposed device to rapidly and efficiently manipulate and separate microparticles of various dimensions, utilizing positive and negative dielectrophoresis (DEP effects. Larger size particles were repelled and concentrated in the center of the dot by negative DEP, while the smaller sizes were attracted and collected by the edge of the dot by positive DEP.

  8. Correlated Coulomb drag in capacitively coupled quantum-dot structures

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-01-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach which accounts for higher-order tunneling (cotunneling....... Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments...

  9. [Fluorescent carbon dots and the application in biomedicine].

    Science.gov (United States)

    Zhang, Shuang; Gao, Hui-Le; Shen, Shun; Wang, Wei-Liang; Qian, Jun

    2014-09-01

    As a new type of carbon nanomaterials, fluorescent carbon dots (fluorescent CDs) have many advantages when compared with the traditional fluorescent probes. They are photoluminescence stable and resistance to photo bleaching. Moreover, they are excellent in biocompatibility, low-toxic and easy to modify. All these above make them a promising optical image material as a probe in optical image. This article reviews structure, the common carbon sources, the preparation methods, and the light-emitting principles of the carbon dots. We also introduce the research progress of fluorescent carbon dots in biomedicine, and the problems need to be resolved in the study of fluorescent CDs.

  10. Wafer scale integration of catalyst dots into nonplanar microsystems

    DEFF Research Database (Denmark)

    Gjerde, Kjetil; Kjelstrup-Hansen, Jakob; Gammelgaard, Lauge;

    2007-01-01

    In order to successfully integrate bottom-up fabricated nanostructures such as carbon nanotubes or silicon, germanium, or III-V nanowires into microelectromechanical systems on a wafer scale, reliable ways of integrating catalyst dots are needed. Here, four methods for integrating sub-100-nm...... diameter nickel catalyst dots on a wafer scale are presented and compared. Three of the methods are based on a p-Si layer utilized as an in situ mask, an encapsulating layer, and a sacrificial window mask, respectively. All methods enable precise positioning of nickel catalyst dots at the end...

  11. Realization of electrically tunable single quantum dot nanocavities

    Energy Technology Data Exchange (ETDEWEB)

    Hofbauer, Felix Florian Georg

    2009-03-15

    We investigated the design, fabrication and optical investigation of electrically tunable single quantum dot-photonic crystal defect nanocavities operating in both the weak and strong coupling regimes of the light matter interaction. We demonstrate that the quantum confined Stark effect can be employed to quickly and reversibly switch the dot-cavity coupling, simply by varying a gate voltage. Our results show that exciton transitions from individual dots can be tuned by up to {proportional_to}4 meV relative to the nanocavity mode, before the emission quenches due to carrier tunneling escape from the dots. We directly probe spontaneous emission, irreversible polariton decay and the statistics of the emitted photons from a single-dot nanocavity in the weak and strong coupling regimes. New information is obtained on the nature of the dot-cavity coupling in the weak coupling regime and electrical control of zero dimensional polaritons is demonstrated for the first time. The structures investigated are p-i-n photodiodes consisting of an 180nm thick free-standing GaAs membrane into which a two dimensional photonic crystal is formed by etching a triangular lattice of air holes. Low mode volume nanocavities (V{sub mode}<1.6 ({lambda}/n){sup 3}) are realized by omitting 3 holes in a line to form L3 cavities and a single layer of InGaAs self-assembled quantum dots is embedded into the midpoint of the membrane. The nanocavities are electrically contacted via 35 nm thick p- and n-doped contact layers in the GaAs membrane. In the weak coupling regime, time resolved spectroscopy reveals a {proportional_to}7 x shortening of the spontaneous emission lifetime as the dot is tuned through the nanocavity mode, due to the Purcell effect. Upon strongly detuning the same quantum dot transition from the nanocavity mode we observe an additional {proportional_to}8 x lengthening of the spontaneous emission lifetime. These observations unequivocally highlight two regimes of dot

  12. Graphene mediated Stark shifting of quantum dot energy levels

    Science.gov (United States)

    Kinnischtzke, Laura; Goodfellow, Kenneth M.; Chakraborty, Chitraleema; Lai, Yi-Ming; Fält, Stefan; Wegscheider, Werner; Badolato, Antonio; Vamivakas, A. Nick

    2016-05-01

    We demonstrate an optoelectronic device comprised of single InAs quantum dots in an n-i-Schottky diode where graphene has been used as the Schottky contact. Deterministic electric field tuning is shown using Stark-shifted micro-photoluminescence from single quantum dots. The extracted dipole moments from the Stark shifts are comparable to conventional devices where the Schottky contact is a semi-transparent metal. Neutral and singly charged excitons are also observed in the well-known Coulomb-blockade plateaus. Our results indicate that graphene is a suitable replacement for metal contacts in quantum dot devices which require electric field control.

  13. Second Bound State of Biexcitons in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Eang

    2003-01-01

    The second bound state of the biexcitons in a quantum dot, with orbital angular momentum L = 1, is reported. By using the method of few-body physics, the binding energy spectra of the second bound state of a biexciton in a GaAs quantum dot with a parabolic confinement have been calculated as a function of the electron-to-hole mass ratio and the quantum dot size. The fact that the biexcitons have a second bound state may aid in the better understanding of their binding mechanism.

  14. Kondo effect in quantum dots and molecular devices

    Institute of Scientific and Technical Information of China (English)

    JIANG Lang; LI Hongxiang; HU Wenping; ZHU Daoben

    2005-01-01

    Kondo effect is a very important many-body phenomenon in condensed matter physics,which explains why the resistance increases as the temperature is lowered (usually <10 K) in dilute magnetic alloy, and why the conductance increases as temperature is decreased in quantum dots. This paper simply introduces equilibrium and non- equilibrium Kondo effects in quantum dots together with the Kondo effect in quantum dots with even number of electrons (when the singlet and triplet states are degenerate). Furthermore, Kondo effect in single atom/molecular transistors is introduced, which indicates a new way to study Kondo effect.

  15. Long lived coherence in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Birkedal, Dan; Leosson, Kristjan; Hvam, Jørn Märcher

    2001-01-01

    We report measurements of ultralong coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time of 372 ps, corresponding to a homogeneous linewidth of 3.5 mu eV, which is significantly smaller than the linewidth observed in single-dot...... luminescence. Time-resolved luminescence measurements show a lifetime of the dot ground state of 800 ps, demonstrating the presence of pure dephasing at finite temperature. The homogeneous width is lifetime limited only at temperatures approaching 0 K....

  16. Thermal Rectification Effect of an Interacting Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    CHEN Xue-Ou; DONG Bing; LEI Xiao-Lin

    2008-01-01

    @@ We investigate the nonlinear thermal transport properties of a single interacting quantum dot with two energy levels tunnel-coupled to two electrodes using nonequilibrium Green function method and Hartree-Fock decoupling approximation. In the case of asymmetric tunnel-couplings to two electrodes, for example, when the upper level of the quantum dot is open for transport, whereas the lower level is blocked, our calculations predict a strong asymmetry for the heat (energy) current, which shows that the quantum dot system may act as a thermal rectifier in this specific situation.

  17. Correlation effects in strain-induced quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, R.; DeVittorio, M.; Cingolani, R.; Molinari, E. [Ist. Nazionale per la Fisica della Materia (INFM) and Dipt. di Ingegneria dell' Innovazione, Univ. Lecce (Italy); Hohenester, U. [INFM and Dipt. di Fisica, Univ. Modena e Reggio E. (Italy); Lipsanen, H.; Tulkki, J. [Optoelectronics Lab. and Lab. of Computational Engineering, Helsinki Univ. of Technology (Finland); Ahopelto, J. [VTT Electronics (Finland); Uchida, K.; Miura, N. [Inst. for Solid State Physics, Univ. of Tokyo (Japan); Arakawa, Y. [Inst. of Industrial Science, Univ. of Tokyo (Japan)

    2001-03-08

    We report on Coulomb correlation effects in the luminescence of strain-induced quantum dots. In single dots, under low power excitation, we observe the rising of sharp lines associated to the formation of excitonic molecules. In the grand-ensemble, in magnetic fields up to 45 T, we observe Darwin-Fock states of the dots to merge into a unique Landau level, with a considerable reduction in the total diamagnetic shift due to the enhanced electron-hole correlation caused by the increased degeneracy of the state. (orig.)

  18. Effect of Intra-Dot Coulomb Interaction on Andreev Reflection in Normal-Metal/Quantum-Dot/Superconductor System

    Institute of Scientific and Technical Information of China (English)

    ZHU Yu; SUN Qing-Feng; LIN Tsung-Han

    2001-01-01

    We investigate the effect of intra-dot Coulomb interaction on the Andreev reflection in a normalmetal/quantum-dot/superconductor (N-QD-S) system with multiple levels in the quantum dot, in the regime where the intra-dot interacting constant is comparable to the energy gap of superconducting lead. By using nonequilibrium Green function method, the averaged occupation of electrons in the quantum dot and the Andreev reflection (AR) current are studied. Comparing to the case of non-interacting quantum dot, the system shows significant changes for the a two-step-like behavior; and the I-Vg shows two groups of peaks, separated by U and with equal heights, where Vg is the gate voltage and U denotes the intra-dot Coulomb interaction constant. (ii) For finite bias voltage, dips, superposed V ≥ U/2, extra AR current peaks occur between the two groups of the peaks. Besides, the properties of the heights of the AR current peaks are more complicated.``

  19. Silicon quantum dots for biological applications.

    Science.gov (United States)

    Chinnathambi, Shanmugavel; Chen, Song; Ganesan, Singaravelu; Hanagata, Nobutaka

    2014-01-01

    Semiconductor nanoparticles (or quantum dots, QDs) exhibit unique optical and electronic properties such as size-controlled fluorescence, high quantum yields, and stability against photobleaching. These properties allow QDs to be used as optical labels for multiplexed imaging and in drug delivery detection systems. Luminescent silicon QDs and surface-modified silicon QDs have also been developed as potential minimally toxic fluorescent probes for bioapplications. Silicon, a well-known power electronic semiconductor material, is considered an extremely biocompatible material, in particular with respect to blood. This review article summarizes existing knowledge related to and recent research progress made in the methods for synthesizing silicon QDs, as well as their optical properties and surface-modification processes. In addition, drug delivery systems and in vitro and in vivo imaging applications that use silicon QDs are also discussed.

  20. Quantum dots for next-generation photovoltaics

    Directory of Open Access Journals (Sweden)

    Octavi E. Semonin

    2012-11-01

    Full Text Available Colloidal quantum-confined semiconductor nanostructures are an emerging class of functional material that are being developed for novel solar energy conversion strategies. One of the largest losses in a bulk or thin film solar cell occurs within a few picoseconds after the photon is absorbed, as photons with energy larger than the semiconductor bandgap produce charge-carriers with excess kinetic energy, which is then dissipated via phonon emission. Semiconductor nanostructures, where at least one dimension is small enough to produce quantum confinement effects, provide new pathways for controlling energy flow and therefore have the potential to increase the efficiency of the primary photoconversion step. In this review, we provide the current status of research efforts towards utilizing the unique properties of colloidal quantum dots (nanocrystals confined in three dimensions in prototype solar cells and demonstrate that these unique systems have the potential to bypass the Shockley-Queisser single-junction limit for solar photon conversion.

  1. Preparation and Application of Fluorescent Carbon Dots

    Directory of Open Access Journals (Sweden)

    Jun Zuo

    2015-01-01

    Full Text Available Fluorescent carbon dots (CDs are a novel type of fluorescent nanomaterials, which not only possess the specific quantum confinement effects of nanomaterials due to the small size of nanomaterials, but also have good biocompatibility and high fluorescence. Meanwhile, fluorescence CDs overcome the shortcomings of high toxicity of traditional nanomaterials. Moreover, the preparation procedure of fluorescent CDs is simple and easy. Therefore, fluorescent CDs have great potential applied in photocatalysis, biochemical sensing, bioimaging, drug delivery, and other related areas. In this paper, recent hot researches on fluorescent CDs are reviewed and some problems in the progress of fluorescent CDs are also summarized. At last, a future outlook in this direction is presented.

  2. Quantum Dot Devices for Optical Signal Processing

    DEFF Research Database (Denmark)

    Chen, Yaohui

    . Additional to the static linear amplication properties, we focus on exploring the gain dynamics on the time scale ranging from sub-picosecond to nanosecond. In terms of optical signals that have been investigated, one is the simple sinusoidally modulated optical carrier with a typical modulation frequency...... range of 1-100 gigahertz. Our simulations reveal the role of ultrafast intradot carrier dynamics in enhancing modulation bandwidth of quantum dot semiconductor optical ampliers. Moreover, the corresponding coherent gain response also provides rich dispersion contents over a broad bandwidth. One...... important implementation is recently boosted by the research in slow light. The idea is to migrate such dynamical gain knowledge for the investigation of microwave phase shifter based on semiconductor optical waveguide. Our study reveals that phase shifting based on the conventional semiconductor optical...

  3. Wet electron microscopy with quantum dots.

    Science.gov (United States)

    Timp, Winston; Watson, Nicki; Sabban, Alon; Zik, Ory; Matsudaira, Paul

    2006-09-01

    Wet electron microscopy (EM) is a new imaging method with the potential to allow higher spatial resolution of samples. In contrast to most EM methods, it requires little time to perform and does not require complicated equipment or difficult steps. We used this method on a common murine macrophage cell line, IC-21, in combination with various stains and preparations, to collect high resolution images of the actin cytoskeleton. Most importantly, we demonstrated the use of quantum dots in conjunction with this technique to perform light/electron correlation microscopy. We found that wet EM is a useful tool that fits into a niche between the simplicity of light microscopy and the high spatial resolution of EM.

  4. Coherent spin dynamics in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Amand, T.; Senes, M.; Marie, X.; Renucci, P. [Laboratoire de Nanophysique, Magnetisme et Optoelectronique-LPMC, INSA, 135 avenue de Rangueil, 31077 Toulouse cedex 4 (France); Urbaszek, B. [Laboratoire de Nanophysique, Magnetisme et Optoelectronique-LPMC, INSA, 135 avenue de Rangueil, 31077 Toulouse cedex 4 (France); Department of Physics, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Krebs, O.; Laurent, S.; Voisin, P. [Laboratoire de Photonique et Nanostructures, route de Nozay, 91460 Marcoussis (France); Warburton, R.J. [Department of Physics, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2005-05-01

    The anisotropic exchange interaction (AEI) between electrons and holes is shown to play a central role in quantum dots (QDs) spin dynamics. In neutral QDs, AEI is at the origin of spin quantum beats observed under resonant excitation between the lowest energy doublet of linearly dipole-active eigenstates. In negatively charged QDs, AEI is at the origin of QD emission with opposite helicity to the optic al excitation, under non-resonant excitation conditions. Finally, the possibility of leaving a spin information in the system after recombination of the photo-injected electron-hole pair is discussed with respect to the type and the level of the doping. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. PREFACE: Quantum dots as probes in biology

    Science.gov (United States)

    Cieplak, Marek

    2013-05-01

    The recent availability of nanostructured materials has resulted in an explosion of research focused on their unique optical, thermal, mechanical and magnetic properties. Optical imagining, magnetic enhancement of contrast and drug delivery capabilities make the nanoparticles of special interest in biomedical applications. These materials have been involved in the development of theranostics—a new field of medicine that is focused on personalized tests and treatment. It is likely that multimodal nanomaterials will be responsible for future diagnostic advances in medicine. Quantum dots (QD) are nanoparticles which exhibit luminescence either through the formation of three-dimensional excitons or excitations of the impurities. The excitonic luminescence can be tuned by changing the size (the smaller the size, the higher the frequency). QDs are usually made of semiconducting materials. Unlike fluorescent proteins and organic dyes, QDs resist photobleaching, allow for multi-wavelength excitations and have narrow emission spectra. The techniques to make QDs are cheap and surface modifications and functionalizations can be implemented. Importantly, QDs could be synthesized to exhibit useful optomagnetic properties and, upon functionalization with an appropriate biomolecule, directed towards a pre-selected target for diagnostic imaging and photodynamic therapy. This special issue on Quantum dots in Biology is focused on recent research in this area. It starts with a topical review by Sreenivasan et al on various physical mechanisms that lead to the QD luminescence and on using wavelength shifts for an improvement in imaging. The next paper by Szczepaniak et al discusses nanohybrids involving QDs made of CdSe coated by ZnS and combined covalently with a photosynthetic enzyme. These nanohybrids are shown to maintain the enzymatic activity, however the enzyme properties depend on the size of a QD. They are proposed as tools to study photosynthesis in isolated

  6. La participación social en la protección y gestión de los bienes agrarios inscritos en la lista del patrimonio mundial : ejemplos de buenas prácticas y estrategias de futuro

    OpenAIRE

    Martínez Yáñez, Celia

    2015-01-01

    La participación de las personas y las comunidades que viven en lugares inscritos en la Lista del Patrimonio Mundial (o que se ven directamente afectadas por la inscripción) en la toma de decisiones respecto a su identificación, protección y gestión, es uno de los principales retos que debe afrontar la Convención de Patrimonio Mundial para alcanzar su anhelada credibilidad. Esta participación real y activa, exigible en todos los tipos de bienes culturales y naturales (independientemente de su...

  7. The using differences and contrasts of the French adverb bien、très and beaucoupp%法语副词bien,très,beaucoup用法的区别和比较

    Institute of Scientific and Technical Information of China (English)

    宋玉芳

    2010-01-01

    法语中有很多表示程度的副词,其中副词bien , très, beaucoup的用法对于初学者来说最容易混淆.本文首先对这三个词的各自的特殊用法分别做了分析举例.然后再两两加以比较区别,并通过例子来印证,加深印象.

  8. Tercer Premio del I Concurso de monólogos científicos de la Facultad de Ciencias del Mar y Ambientales. Saber comer para crecer muy bien. La teoría endosimbiótica

    OpenAIRE

    Rodríguez López, Jaime; Cabrera Castro, Remedios; López López, José Antonio; Albendín García, Gemma

    2015-01-01

    La teoría endosimbiótica fue propuesta por Lynn Margulis en 1967 y como tantas otras al principio no fue bien valorada por los científicos. Esta teoría plantea esencialmente que algunos de los orgánulos de las células eucariotas, en particular las mitocondrias y los plastos, fueron en su momento organismos procariontes de vida libre (bacterias), que probablemente tras haber sido fagocitadas no fueron digeridas llegando a formar parte y creando una relación dependiente de la célula que las fag...

  9. 78 FR 48868 - Proposed Cercla Administrative Cost Recovery Settlement; MassDOT, MassDOT Route 1 Right-of-Way...

    Science.gov (United States)

    2013-08-12

    ... AGENCY Proposed Cercla Administrative Cost Recovery Settlement; MassDOT, MassDOT Route 1 Right-of-Way...), concerning the MassDOT Route 1 Right-of-Way Site in Chelsea, Massachusetts with the following Settling Party... should refer to: In re: MassDOT Route 1 Right-of- Way Site, U.S. EPA Docket No.01-2013-0031. FOR...

  10. Charge-extraction strategies for colloidal quantum dot photovoltaics

    KAUST Repository

    Lan, Xinzheng

    2014-02-20

    The solar-power conversion efficiencies of colloidal quantum dot solar cells have advanced from sub-1% reported in 2005 to a record value of 8.5% in 2013. Much focus has deservedly been placed on densifying, passivating and crosslinking the colloidal quantum dot solid. Here we review progress in improving charge extraction, achieved by engineering the composition and structure of the electrode materials that contact the colloidal quantum dot film. New classes of structured electrodes have been developed and integrated to form bulk heterojunction devices that enhance photocharge extraction. Control over band offsets, doping and interfacial trap state densities have been essential for achieving improved electrical communication with colloidal quantum dot solids. Quantum junction devices that not only tune the optical absorption spectrum, but also provide inherently matched bands across the interface between p-and n-materials, have proven that charge separation can occur efficiently across an all-quantum-tuned rectifying junction. © 2014 Macmillan Publishers Limited.

  11. Advanced Epitaxial Lift-Off Quantum Dot Photovoltaic Devices Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a high-efficiency, triple-junction, epitaxial lift-off (ELO) solar cell by incorporating quantum dots (QDs) within the current-limiting...

  12. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  13. A fast "hybrid" silicon double quantum dot qubit

    CERN Document Server

    Shi, Zhan; Prance, J R; Gamble, John King; Koh, Teck Seng; Shim, Yun-Pil; Hu, Xuedong; Savage, D E; Lagally, M G; Eriksson, M A; Friesen, Mark; Coppersmith, S N

    2011-01-01

    We propose a quantum dot qubit architecture that has an attractive combination of speed and fabrication simplicity. It consists of a double quantum dot with one electron in one dot and two electrons in the other. The qubit itself is a set of two states with total spin quantum numbers $S^2=3/4$ ($S=\\half$) and $S_z = -\\half$, with the two different states being singlet and triplet in the doubly occupied dot. The architecture is relatively simple to fabricate, a universal set of fast operations can be implemented electrically, and the system has potentially long decoherence times. These are all extremely attractive properties for use in quantum information processing devices.

  14. Probing individual quantum dots: noise in self-assembled systems.

    Science.gov (United States)

    Vicaro, K O; Gutiérrez, H R; Seabra, A C; Schulz, P A; Cotta, M A

    2009-11-01

    In this work we explore the noise characteristics in lithographically-defined two terminal devices containing self-assembled InAs/InP quantum dots. The experimental ensemble of InAs dots show random telegraph noise (RTN) with tuneable relative amplitude-up to 150%-in well defined temperature and source-drain applied voltage ranges. Our numerical simulation indicates that the RTN signature correlates with a very low number of quantum dots acting as effective charge storage centres in the structure for a given applied voltage. The modulation in relative amplitude variation can thus be associated to the altered electrostatic potential profile around such centres and enhanced carrier scattering provided by a charged dot.

  15. Open quantum dots in graphene: Scaling relativistic pointer states

    Science.gov (United States)

    Ferry, D. K.; Huang, L.; Yang, R.; Lai, Y.-C.; Akis, R.

    2010-04-01

    Open quantum dots provide a window into the connection between quantum and classical physics, particularly through the decoherence theory, in which an important set of quantum states are not "washed out" through interaction with the environment-the pointer states provide connection to trapped classical orbits which remain stable in the dots. Graphene is a recently discovered material with highly unusual properties. This single layer, one atom thick, sheet of carbon has a unique bandstructure, governed by the Dirac equation, in which charge carriers imitate relativistic particles with zero rest mass. Here, an atomic orbital-based recursive Green's function method is used for studying the quantum transport. We study quantum fluctuations in graphene and bilayer graphene quantum dots with this recursive Green's function method. Finally, we examine the scaling of the domiant fluctuation frequency with dot size.

  16. Berry phase jumps and giant nonreciprocity in Dirac quantum dots

    Science.gov (United States)

    Rodriguez-Nieva, Joaquin F.; Levitov, Leonid S.

    2016-12-01

    We predict that a strong nonreciprocity in the resonance spectra of Dirac quantum dots can be induced by the Berry phase. The nonreciprocity arises in relatively weak magnetic fields and is manifest in anomalously large field-induced splittings of quantum dot resonances which are degenerate at B =0 due to time-reversal symmetry. This exotic behavior, which is governed by field-induced jumps in the Berry phase of confined electronic states, is unique to quantum dots in Dirac materials and is absent in conventional quantum dots. The effect is strong for gapless Dirac particles and can overwhelm the B -induced orbital and Zeeman splittings. A finite Dirac mass suppresses the effect. The nonreciprocity, predicted for generic two-dimensional Dirac materials, is accessible through Faraday and Kerr optical rotation measurements and scanning tunneling spectroscopy.

  17. Photolithographic process for the patterning of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Na, Young Joo; Park, Sang Joon; Lee, Sang Wha [Department of Chemical and Bioengineering, Kyungwon University, Seongnam-si, Gyeonggi-Do 461-701 (Korea, Republic of); Kim, Jong Sung [Department of Chemical and Bioengineering, Kyungwon University, Seongnam-si, Gyeonggi-Do 461-701 (Korea, Republic of)], E-mail: jskim@kyungwon.ac.kr

    2008-09-15

    Recently, quantum dots have been used as molecular probes substituting for conventional organic fluorophores. Quantum dots are stable against photobleaching and have more controllable emission bands, broader absorption spectra, and higher quantum yields. In this study, an array of ZnS-coated CdSe quantum dots on a slide glass has been prepared by photolithographic method. The array pattern was prepared using a positive photoresist (AZ1518) and developer (AZ351). The patterned glass was silanized with 3-aminopropyltriethoxysilane (APTES), and carboxyl-coated quantum dots were selectively attached onto the array pattern. The silanization was examined by measuring contact angle and the surface of the array pattern was analyzed using AFM and fluorescent microscope.

  18. Hydrogenic Donor in a Spherical Quantum Dot with Different Confinements

    Institute of Scientific and Technical Information of China (English)

    A. John Peter; K. Navaneethakrishnan

    2009-01-01

    Binding energies of a hydrogenic donor in a spherical GaAs quantum dot surrounded by Ga1-xAlxAs matrix are calculated. The results are presented for realistic barrier heights corresponding to different values of x (x < 0.4). The calculations are performed under two different conditions: (i) a spherical dot with square well confinement and (ii) a dot with parabolic potential well confinement. The results show that (i) the donor ionization energies are always higher under parabolic confinement as compared to a dot of the same radius under square well confinement and (ii) the oscillator strengths coupling ground state with excited states are two orders larger under parabolic confinement. Our results are in agreement with the results of other researchers.

  19. Optically induced magnetization in diluted magnetic quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    John Peter, A. [Government Arts College, Melur 625 106, Madurai (India)], E-mail: a_johnpeter@rediffmail.com; Lily Mary Eucharista, K. [Arul Anandar College, Karumathur 625 514, Madurai (India)

    2009-03-15

    We report the effect of intense laser field on donor impurities in a semimagnetic Cd{sub 1-x{sub in}}Mn{sub x{sub in}}Te/Cd{sub 1-x{sub out}}Mn{sub x{sub out}}Te quantum dot. The spin polaronic energy of different Mn{sup 2+} is evaluated for different dot radii using a mean field theory in the presence of laser field. Magnetization is calculated for various concentrations of Mn{sup 2+} ions with different dot sizes. Significant magnetization of Mn spins can be obtained through the formation of polarized exciton magnetic polarons (EMPs). A rapid decrease of the laser dressed donor ionization energy for different values of dot sizes with increasing field intensity is predicted. Also, it is found that the polarization of EMPs increases rapidly at higher excitation energies.

  20. A triple quantum dot based nano-electromechanical memory device

    Energy Technology Data Exchange (ETDEWEB)

    Pozner, R.; Lifshitz, E. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Solid State Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Peskin, U., E-mail: uri@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2015-09-14

    Colloidal quantum dots (CQDs) are free-standing nano-structures with chemically tunable electronic properties. This tunability offers intriguing possibilities for nano-electromechanical devices. In this work, we consider a nano-electromechanical nonvolatile memory (NVM) device incorporating a triple quantum dot (TQD) cluster. The device operation is based on a bias induced motion of a floating quantum dot (FQD) located between two bound quantum dots (BQDs). The mechanical motion is used for switching between two stable states, “ON” and “OFF” states, where ligand-mediated effective interdot forces between the BQDs and the FQD serve to hold the FQD in each stable position under zero bias. Considering realistic microscopic parameters, our quantum-classical theoretical treatment of the TQD reveals the characteristics of the NVM.

  1. Quantum Dots: An Experiment for Physical or Materials Chemistry

    Science.gov (United States)

    Winkler, L. D.; Arceo, J. F.; Hughes, W. C.; DeGraff, B. A.; Augustine, B. H.

    2005-01-01

    An experiment is conducted for obtaining quantum dots for physical or materials chemistry. This experiment serves to both reinforce the basic concept of quantum confinement and providing a useful bridge between the molecular and solid-state world.

  2. Type 2 quantum dots in Ge/Si system

    CERN Document Server

    Dvurechenskij, A V

    2001-01-01

    The results on the electronic structure of spatially indirect excitons, multiparticle excitonic complexes, and negative interband photoconductivity in arrays of Ge/Si type 2 quantum dots are presented. These data have been compared with the well known results for type 2 A sup I sup I sup I B sup V and A sup I sup I B sup V sup I -based heterostructures with quantum dots. Fundamental physical phenomena are found to be the result of an increase in the binding energy of excitons in quantum dots as compared with that of free excitons in bulk homogeneous materials; the shortwave shift of exciton transition energy at multiparticle complexes production (charges excitons, biexcitons), as well as the trapping of equilibrium carrier by localized states induced by the charged quantum dot electric field

  3. Phonon-assisted decoherence and tunneling in quantum dot molecules

    DEFF Research Database (Denmark)

    Grodecka-Grad, Anna; Foerstner, Jens

    2011-01-01

    We study the influence of the phonon environment on the electron dynamics in a doped quantum dot molecule. A non-perturbative quantum kinetic theory based on correlation expansion is used in order to describe both diagonal and off-diagonal electron-phonon couplings representing real and virtual...... processes with relevant acoustic phonons. We show that the relaxation is dominated by phonon-assisted electron tunneling between constituent quantum dots and occurs on a picosecond time scale. The dependence of the time evolution of the quantum dot occupation probabilities on the energy mismatch between...... the quantum dots is studied in detail. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)...

  4. Dephasing and hyperfine interaction in carbon nanotubes double quantum dots

    DEFF Research Database (Denmark)

    Reynoso, Andres Alejandro; Flensberg, Karsten

    2012-01-01

    We study theoretically the return probability experiment, which is used to measure the dephasing time T-2*, in a double quantum dot (DQD) in semiconducting carbon nanotubes with spin-orbit coupling and disorder-induced valley mixing. Dephasing is due to hyperfine interaction with the spins of the C......-13 nuclei. Due to the valley and spin degrees of freedom, four bounded states exist for any given longitudinal mode in the quantum dot. At zero magnetic field, the spin-orbit coupling and the valley mixing split those four states into two Kramers doublets. The valley-mixing term for a given dot...... is determined by the intradot disorder; this leads to (i) states in the Kramers doublets belonging to different dots being different, and (ii) nonzero interdot tunneling amplitudes between states belonging to different doublets. We show that these amplitudes give rise to new avoided crossings, as a function...

  5. A Novel Particle Detector: Quantum Dot Doped Liquid Scintillator

    Science.gov (United States)

    Winslow, Lindley; Conrad, Janet; Jerry, Ruel

    2010-02-01

    Quantum dots are semiconducting nanocrystals. When excited by light shorter then their characteristic wavelength, they re-emit in a narrow band around this wavelength. The size of the quantum is proportional to the characteristic wavelength so they can be tuned for many applications. CdS quantum dots are made in wavelengths from 360nm to 460nm, a perfect range for the sensitivity of photo-multiplier tubes. The synthesis of quantum dots automatically leaves them in toluene, a good organic scintillator and Cd is a particularly interesting material as it has one of the highest thermal neutron cross sections and has several neutrinoless double beta decay and double electron capture isotopes. The performance of quantum dot loaded scintillator compared to standard scintillators is measured and some unique properties presented. )

  6. Nonequilibrium electron transport through quantum dots in the Kondo regime

    DEFF Research Database (Denmark)

    Wölfle, Peter; Paaske, Jens; Rosch, Achim;

    2005-01-01

    Electron transport at large bias voltage through quantum dots in the Kondo regime is described within the perturbative renormalization group extended to nonequilibrium. The conductance, local magnetization, dynamical spin susceptibility and local spectral function are calculated. We show how the ...

  7. Carbon nanotube quantum dots as highly sensitive THz spectrometers

    Science.gov (United States)

    Rinzan, Mohamed; Jenkins, Greg; Drew, Dennis; Shafranjuk, Serhii; Barbara, Paola

    2012-02-01

    We show that carbon nanotube quantum dots (CNT-Dots) coupled to antennas are extremely sensitive, broad-band, terahertz quantum detectors. Their response is due to photon-assisted single-electron tunneling (PASET)[1], but cannot be fully understood with orthodox PASET models[2]. We consider intra-dot excitations and non-equilibrium cooling to explain the anomalous response. REFERENCES: [1] Y. Kawano, S. Toyokawa, T. Uchida and K. Ishibashi, THz photon assisted tunneling in carbon-nanotube quantum dots, Journal of Applied Physics 103, 034307 (2008). [2] P. K. Tien and J. P. Gordon, Multiphoton Process Observed in the Interaction of Microwave Fields with the Tunneling between Superconductor Films, Phys. Rev. 129, 647 (1963).

  8. Non-Markovian spontaneous emission from a single quantum dot

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg; Ates, Serkan; Lund-Hansen, Toke;

    2011-01-01

    We observe non-Markovian dynamics of a single quantum dot when tuned into resonance with a cavity mode. Excellent agreement between experiment and theory is observed providing the first quantitative description of such a system....

  9. Kondo effect for electron transport through an artificial quantum dot

    Institute of Scientific and Technical Information of China (English)

    Sun Ke-Wei; Xiong Shi-Jie

    2006-01-01

    We have calculated the transport properties of electron through an artificial quantum dot by using the numerical renormalization group technique in this paper.We obtain the conductance for the system of a quantum dot which is embedded in a one-dimensional chain in zero and finite temperature cases.The external magnetic field gives rise to a negative magnetoconductance in the zero temperature case.It increases as the external magnetic field increases.We obtain the relation between the coupling coefficient and conductance.If the interaction is big enough to prevent conduction electrons from tunnelling through the dot,the dispersion effect is dominant in this case.In the Kondo temperature regime,we obtain the conductivity of a quantum dot system with Kondo correlation.

  10. Using a quantum dot system to realize perfect state transfer

    Institute of Scientific and Technical Information of China (English)

    Li Ji; Wu Shi-Hai; Zhang Wen-Wen; Xi Xiao-Qiang

    2011-01-01

    There are some disadvantages to Nikolopoulos et al.'s protocol [Nikolopoulos G M,Petrosyan D and Lambropoulos P 2004 Europhys.Lett.65 297] where a quantum dot system is used to realize quantum communication.To overcome these disadvantages,we propose a protocol that uses a quantum dot array to construct a four-qubit spin chain to realize perfect quantum state transfer (PQST).First,we calculate the interaction relation for PQST in the spin chain.Second,we review the interaction between the quantum dots in the Heitler-London approach.Third,we present a detailed program for designing the proper parameters of a quantum dot array to realize PQST.

  11. Calculation of hyperfine interaction in spherical quantum dot

    Science.gov (United States)

    Yakar, Yusuf; Çakır, Bekir; Özmen, Ayhan

    2015-10-01

    In this study, we have calculated the unperturbed wavefunctions and energy eigenvalues of the ground and excited states of a spherical quantum dot, GaAs/AlxGa1-xAs, by using quantum genetic algorithm and Hartree-Fock Roothaan method. Hyperfine coupling constant and hyperfine energy of 1s, 2p, 3d and 4f levels are carried out as a function of dot radius. The results show that the hyperfine constant and hyperfine energy varies rapidly in the strong and medium confining regions as dot radius decreases. It is worth pointing out that dot radius, impurity charge and angular momentum have a strong influence on the hyperfine energy. It is also found that hyperfine energy and hyperfine splitting vary with aluminium concentration ratio x.

  12. [Louis Braille (1809-1852)--inventor of raised dots system].

    Science.gov (United States)

    Maciejewicz, Piotr; Kopacz, Dorota

    2005-01-01

    Louis Braille was born on January 4th 1809 in Coupvray, France. An injury to his eye at the age of three, resulted in total loss of vision. In 1819 he entered the Institute for Blind Youth in Paris. There he would live, study, and later teach. When he was fifteen, he developed system of reading and writing by means of raised dots, which is known today as Braille. The basis of the Braille system is known as a Braille cell. The cell is comprised of six dots numbered in a specific order. Each dot or combination of dots represents a letter of the alphabet. This Braille system has established itself internationally and formed the basic Braille for all languages.

  13. Carbon Dot Based Sensing of Dopamine and Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Upama Baruah

    2014-01-01

    Full Text Available We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascorbic acid, respectively. The quenching constants determined from Stern-Volmer plot were determined to be 5 × 10−4 and 1 × 10−4 for dopamine and ascorbic acid, respectively. A probable mechanism of quenching has been discussed in the paper.

  14. Electro-absorption of silicene and bilayer graphene quantum dots

    Science.gov (United States)

    Abdelsalam, Hazem; Talaat, Mohamed H.; Lukyanchuk, Igor; Portnoi, M. E.; Saroka, V. A.

    2016-07-01

    We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.

  15. Fabrication of quantum-dot devices in graphene

    Directory of Open Access Journals (Sweden)

    Satoshi Moriyama, Yoshifumi Morita, Eiichiro Watanabe, Daiju Tsuya, Shinya Uji, Maki Shimizu and Koji Ishibashi

    2010-01-01

    Full Text Available We describe our recent experimental results on the fabrication of quantum-dot devices in a graphene-based two-dimensional system. Graphene samples were prepared by micromechanical cleavage of graphite crystals on a SiO2/Si substrate. We performed micro-Raman spectroscopy measurements to determine the number of layers of graphene flakes during the device fabrication process. By applying a nanofabrication process to the identified graphene flakes, we prepared a double-quantum-dot device structure comprising two lateral quantum dots coupled in series. Measurements of low-temperature electrical transport show the device to be a series-coupled double-dot system with varied interdot tunnel coupling, the strength of which changes continuously and non-monotonically as a function of gate voltage.

  16. Probing of Unembedded Metallic Quantum Dots with Positrons

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, C G; Denison, A B; Weber, M H; Wilcoxon, J P; Woessner, S; Lynn, K G

    2003-08-01

    We employed the two detector coincident Doppler Broadening Technique (coPAS) to investigate Ag, Au and Ag/Au alloy quantum dots of varying sizes which were deposited in thin layers on glass slides. The Ag quantum dots range from 2 to 3 nm in diameter, while the Ag/Au alloy quantum dots exhibit Ag cores of 2 nm and 3 nm and Au shells of varying thickness. We investigate the possibility of positron confinement in the Ag core due to positron affinity differences between Ag and Au. We describe the results and their significance to resolving the issue of whether positrons annihilate within the quantum dot itself or whether surface and positron escape effects play an important role.

  17. Solution-Processed Nanocrystal Quantum Dot Tandem Solar Cells

    KAUST Repository

    Choi, Joshua J.

    2011-06-03

    Solution-processed tandem solar cells created from nanocrystal quantum dots with size-tuned energy levels are demonstrated. Prototype devices featuring interconnected quantum dot layers of cascaded energy gaps exhibit IR sensitivity and an open circuit voltage, V oc, approaching 1 V. The tandem solar cell performance depends critically on the optical and electrical properties of the interlayer. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Quantum state preparation in semiconductor dots by adiabatic rapid passage

    OpenAIRE

    Wu, Yanwen; Piper, I.M.; Ediger, M.; Brereton, P.; Schmidgall, E. R.; Hugues, M.; Hopkinson, M.; Phillips, R.T.

    2010-01-01

    Preparation of a specific quantum state is a required step for a variety of proposed practical uses of quantum dynamics. We report an experimental demonstration of optical quantum state preparation in a semiconductor quantum dot with electrical readout, which contrasts with earlier work based on Rabi flopping in that the method is robust with respect to variation in the optical coupling. We use adiabatic rapid passage, which is capable of inverting single dots to a specified upper level. We d...

  19. Lindblad theory of dynamical decoherence of quantum-dot excitons

    OpenAIRE

    Eastham, P. R.; Spracklen, A O; Keeling, Jonathan Mark James

    2013-01-01

    We use the Bloch-Redfield-Wangsness theory to calculate the effects of acoustic phonons in coherent control experiments where quantum-dot excitons are driven by shaped laser pulses. This theory yields a generalized Lindblad equation for the density operator of the dot, with time-dependent damping and decoherence due to phonon transitions between the instantaneous dressed states. It captures similar physics to the form recently applied to Rabi oscillation experiments [Ramsay et al., Phys. Rev....

  20. Coupled quantum dot-ring structures by droplet epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Somaschini, C; Bietti, S; Koguchi, N; Sanguinetti, S, E-mail: stefano.sanguinetti@unimib.it [L-NESS and Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy)

    2011-05-06

    The fabrication, by pure self-assembly, of GaAs/AlGaAs dot-ring quantum nanostructures is presented. The growth is performed via droplet epitaxy, which allows for the fine control, through As flux and substrate temperature, of the crystallization kinetics of nanometer scale metallic Ga reservoirs deposited on the surface. Such a procedure permits the combination of quantum dots and quantum rings into a single, multi-functional, complex quantum nanostructure.

  1. Progress in the toxicological researches for quantum dots

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Quantum dots (QDs) have received more and more attention as a novel example of nanomaterials. Due to their unique fluorescent characteristics,quantum dots have been successfully applied in biotech-nology and medicine applications. Recently,the toxicity and the potential environmental effects of QDs have become a research hotspot. In this paper,toxicological effects of QDs are reviewed,and the prospects and research directions are given based on the analysis of this research field.

  2. Programmable Periodicity of Quantum Dot Arrays with DNA Origami Nanotubes

    Science.gov (United States)

    2010-01-01

    To fabricate quantum dot arrays with programmable periodicity, functionalized DNA origami nanotubes were developed. Selected DNA staple strands were biotin-labeled to form periodic binding sites for streptavidin-conjugated quantum dots. Successful formation of arrays with periods of 43 and 71 nm demonstrates precise, programmable, large-scale nanoparticle patterning; however, limitations in array periodicity were also observed. Statistical analysis of AFM images revealed evidence for steric hindrance or site bridging that limited the minimum array periodicity. PMID:20681601

  3. Quantum Optics with Quantum Dots in Photonic Nanowires

    DEFF Research Database (Denmark)

    Gérard, J.-M.; Claudon, J.; Bleuse, J.;

    2011-01-01

    We review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices.......We review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices....

  4. Yellowish dots in the retina: a finding of ocular syphilis?

    OpenAIRE

    Renan Albert Mendonça Rodrigues; Heloisa Moraes do Nascimento; Cristina Muccioli

    2014-01-01

    Here we report the occurrence of pale yellowish perivascular preretinal dots in 12 patients with ocular syphilis. A case series of these patients was examined between March and October 2012 at the Uveitis Sector of Universidade Federal de São Paulo. After diagnostic confirmation of syphilis, fundus photographs and optical coherence tomography (OCT) were performed to verify the localization of the dots, and patients were treated with IV crystalline penicillin for 14 days. The study comprised 1...

  5. Ultrafast optical signal processing using semiconductor quantum dot amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    The linear and nonlinear properties of quantum dot amplifiers are discussed on the basis of an extensive theoretical model. These devices show great potential for linear amplification as well as ultrafast signal processing.......The linear and nonlinear properties of quantum dot amplifiers are discussed on the basis of an extensive theoretical model. These devices show great potential for linear amplification as well as ultrafast signal processing....

  6. Solution-processed nanocrystal quantum dot tandem solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Joshua J.; Lim, Yee-Fun [School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853 (United States); Wenger, Whitney N.; Hoffman, Rachel S.; Hanrath, Tobias [School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853 (United States); Luria, Justin; Marohn, John A. [Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853 (United States); Jasieniak, Jacek [CSIRO Materials Science and Engineering, Bayview Ave, Clayton, Victoria 3168 (Australia)

    2011-07-26

    Solution-processed tandem solar cells created from nanocrystal quantum dots with size-tuned energy levels are demonstrated. Prototype devices featuring interconnected quantum dot layers of cascaded energy gaps exhibit IR sensitivity and an open circuit voltage, V{sub oc}, approaching 1 V. The tandem solar cell performance depends critically on the optical and electrical properties of the interlayer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Optical phonons in Ge quantum dots obtained on Si(111)

    CERN Document Server

    Talochkin, A B

    2002-01-01

    The light combination scattering on the optical phonons in the Ge quantum dots, obtained on the Si surface of the (111) orientation through the molecular-beam epitaxy, is studied. The series of lines, connected with the phonon spectrum quantization, was observed. It is shown, that the phonon modes frequencies are well described by the elastic properties and dispersion of the voluminous Ge optical phonons. The value of the Ge quantum dots deformation is determined

  8. Quantum Entanglement of Quantum Dot Spin Using Flying Qubits

    Science.gov (United States)

    2015-05-01

    previously to optically isolate single quantum dots, and adopted a high NA confocal fiber setup that allows for single quantum dot resolution and the...960nm, to telecom wavelength (1.55 microns) for long distance transmission in fibers . Work toward these goals began with non QuEST support from...been to advance the frontier of quantum entangled semiconductor electrons using ultrafast optical techniques. The approach is based on

  9. Intraband Relaxation and Its Influences on Quantum Dot Lasers

    Institute of Scientific and Technical Information of China (English)

    DENG Sheng-Ling; HUANG Yong-Zhen; YU Li-Juan

    2005-01-01

    @@ A comprehensive two-level numerical model is developed to describe carrier distribution in a quantum-dot laser. Light-emission spectra with different intraband relaxation rates (2ps, 7.5ps and 20ps) are calculated and analysed to investigate the influence of relaxation rates on performance of the quantum-dot laser. The results indicate that fast intraband relaxation favours not only the ground state single mode operation but also the higher injection efficiency.

  10. Dynamical symmetries in Kondo tunneling through complex quantum dots.

    Science.gov (United States)

    Kuzmenko, T; Kikoin, K; Avishai, Y

    2002-10-07

    Kondo tunneling reveals hidden SO(n) dynamical symmetries of evenly occupied quantum dots. As is exemplified for an experimentally realizable triple quantum dot in parallel geometry, the possible values n=3,4,5,7 can be easily tuned by gate voltages. Following construction of the corresponding o(n) algebras, scaling equations are derived and Kondo temperatures are calculated. The symmetry group for a magnetic field induced anisotropic Kondo tunneling is SU(2) or SO(4).

  11. Quantum optics with quantum dots in photonic nanowires

    DEFF Research Database (Denmark)

    We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices.......We will review recent studies performed on InAs quantum dots embedded in GaAs photonic wires, which highlight the strong interest of the photonic wire geometry for quantum optics experiments and quantum optoelectronic devices....

  12. THz Electro-absorption Effect in Quantum Dots

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Monozon, Boris S.; Livshits, Daniil A.;

    2011-01-01

    Instantaneous electro-absorption effect in quantum dots, induced by electric field of THz pulse with 3 THz bandwidth is demonstrated in THz pump - optical probe experiment. This effect may be promising for Tbit/s wireless transmission systems.......Instantaneous electro-absorption effect in quantum dots, induced by electric field of THz pulse with 3 THz bandwidth is demonstrated in THz pump - optical probe experiment. This effect may be promising for Tbit/s wireless transmission systems....

  13. Spin-orbit-enhanced Wigner localization in quantum dots

    DEFF Research Database (Denmark)

    Cavalli, Andrea; Malet, F.; Cremon, J. C.;

    2011-01-01

    We investigate quantum dots with Rashba spin-orbit coupling in the strongly-correlated regime. We show that the presence of the Rashba interaction enhances the Wigner localization in these systems, making it achievable for higher densities than those at which it is observed in Rashba-free quantum...... dots. Recurring shapes in the pair distribution functions of the yrast spectrum, which might be associated with rotational and vibrational modes, are also reported....

  14. Progress in the toxicological researches for quantum dots

    Institute of Scientific and Technical Information of China (English)

    LI HongCheng; ZHOU QunFang; LIU Wei; YAN Bing; ZHAO Yibing; JIANG GuiBin

    2008-01-01

    Quantum dots (QDs) have Received more and more attention as a novel example of nanomaterials. Due to their unique fluorescent characteristics, quantum dots have been successfully applied in biotech-nology and medicine applications. Recently, the toxicity and the potential environmental effects of QDs have become a research hotspot. In this paper, toxicological effects of QDs are reviewed, and the prospects and research directions are given based on the analysis of this research field.

  15. Semiconductor Quantum Dots in Chemical Sensors and Biosensors

    OpenAIRE

    Nikos Chaniotakis; Frasco, Manuela F.

    2009-01-01

    Quantum dots are nanometre-scale semiconductor crystals with unique optical properties that are advantageous for the development of novel chemical sensors and biosensors. The surface chemistry of luminescent quantum dots has encouraged the development of multiple probes based on linked recognition molecules such as peptides, nucleic acids or small-molecule ligands. This review overviews the design of sensitive and selective nanoprobes, ranging from the type of target molecules to the optical ...

  16. Scalable quantum computer architecture with coupled donor-quantum dot qubits

    Science.gov (United States)

    Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

    2014-08-26

    A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

  17. Rhizopus stolonifer mediated biosynthesis of biocompatible cadmium chalcogenide quantum dots.

    Science.gov (United States)

    Mareeswari, P; Brijitta, J; Harikrishna Etti, S; Meganathan, C; Kaliaraj, Gobi Saravanan

    2016-12-01

    We report an efficient method to biosynthesize biocompatible cadmium telluride and cadmium sulphide quantum dots from the fungus Rhizopus stolonifer. The suspension of the quantum dots exhibited purple and greenish-blue luminescence respectively upon UV light illumination. Photoluminescence spectroscopy, X-ray diffraction, and transmission electron microscopy confirms the formation of the quantum dots. From the photoluminescence spectrum the emission maxima is found to be 424 and 476nm respectively. The X-ray diffraction of the quantum dots matches with results reported in literature. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay for cell viability evaluation carried out on 3-days transfer, inoculum 3×10(5) cells, embryonic fibroblast cells lines shows that more than 80% of the cells are viable even after 48h, indicating the biocompatible nature of the quantum dots. A good contrast in imaging has been obtained upon incorporating the quantum dots in human breast adenocarcinoma Michigan Cancer Foundation-7 cell lines.

  18. Colloidal quantum dot photovoltaics: The effect of polydispersity

    KAUST Repository

    Zhitomirsky, David

    2012-02-08

    The size-effect tunability of colloidal quantum dots enables facile engineering of the bandgap at the time of nanoparticle synthesis. The dependence of effective bandgap on nanoparticle size also presents a challenge if the size dispersion, hence bandgap variability, is not well-controlled within a given quantum dot solid. The impact of this polydispersity is well-studied in luminescent devices as well as in unipolar electronic transport; however, the requirements on monodispersity have yet to be quantified in photovoltaics. Here we carry out a series of combined experimental and model-based studies aimed at clarifying, and quantifying, the importance of quantum dot monodispersity in photovoltaics. We successfully predict, using a simple model, the dependence of both open-circuit voltage and photoluminescence behavior on the density of small-bandgap (large-diameter) quantum dot inclusions. The model requires inclusion of trap states to explain the experimental data quantitatively. We then explore using this same experimentally tested model the implications of a broadened quantum dot population on device performance. We report that present-day colloidal quantum dot photovoltaic devices with typical inhomogeneous linewidths of 100-150 meV are dominated by surface traps, and it is for this reason that they see marginal benefit from reduction in polydispersity. Upon eliminating surface traps, achieving inhomogeneous broadening of 50 meV or less will lead to device performance that sees very little deleterious impact from polydispersity. © 2012 American Chemical Society.

  19. Emission redistribution from a quantum dot-bowtie nanoantenna

    Science.gov (United States)

    Regler, Armin; Schraml, Konrad; Lyamkina, Anna A.; Spiegl, Matthias; Müller, Kai; Vuckovic, Jelena; Finley, Jonathan J.; Kaniber, Michael

    2016-07-01

    We present a combined experimental and simulation study of a single self-assembled InGaAs quantum dot coupled to a nearby (˜25 nm) plasmonic antenna. Microphotoluminescence spectroscopy shows a ˜2.4× increase of intensity, which is attributed to spatial far-field redistribution of the emission from the quantum dot-antenna system. Power-dependent studies show similar saturation powers of 2.5 μW for both coupled and uncoupled quantum dot emission in polarization-resolved measurements. Moreover, time-resolved spectroscopy reveals the absence of Purcell enhancement of the quantum dot coupled to the antenna as compared with an uncoupled dot, yielding comparable exciton lifetimes of τ˜0.5 ns. This observation is supported by numerical simulations, suggesting only minor Purcell-effects of antenna separations >25 nm. The observed increased emission from a coupled quantum dot-plasmonic antenna system is found to be in good qualitative agreement with numerical simulations and will lead to a better understanding of light-matter coupling in such semiconductor-plasmonic hybrid systems.

  20. Emission redistribution from a quantum dot-bowtie nanoantenna

    CERN Document Server

    Regler, A; Lyamkina, A; Spiegl, M; Müller, K; Vuckovic, J; Finley, J J; Kaniber, M

    2016-01-01

    We present a combined experimental and simulation study of a single self-assembled InGaAs quantum dot coupled to a nearby ($\\sim 25nm$) plasmonic antenna. Micro-photoluminescence spectroscopy shows a $\\sim 2.4\\times$ increase of intensity, which is attributed to spatial far-field redistribution of the emission from the quantum dot-antenna system. Power-dependent studies show similar saturation powers of $2.5\\mu W$ for both coupled and uncoupled quantum dot emission in polarization-resolved measurements. Moreover, time-resolved spectroscopy reveals the absence of Purcell-enhancement of the quantum dot coupled to the antenna as compared to an uncoupled dot, yielding comparable exciton lifetimes of $\\tau\\sim0.5ns$. This observation is supported by numerical simulations, suggesting only minor Purcell-effects of $25nm$. The observed increased emission from a coupled quantum dot-plasmonic antenna system is found to be in good qualitative agreement with numerical simulations and will lead to a better understanding o...

  1. Thermopower of few-electron quantum dots with Kondo correlations

    Science.gov (United States)

    Ye, Lvzhou

    2015-03-01

    The thermopower of few-electron quantum dots is crucially influenced by on-dot electron-electron interactions, particularly in the presence of Kondo correlations. We present a comprehensive picture which elucidates the underlying relations between the thermopower and the spectral density function of two-level quantum dots. The effects of various electronic states, including the Kondo states originating from both spin and orbital degrees of freedom, are clearly unraveled. With these insights, we have exemplified an effective and viable way to control the sign of thermopower of Kondo-correlated quantum dots. This is realized by tuning the temperature and by selecting the appropriate level spacing and Coulomb repulsion strength. Such a physical picture is affirmed by accurate numerical data obtained with a hierarchical equations of motion approach. Our understandings and findings provide useful insights into controlling the direction of electric (heat) current through a quantum dot by applying a temperature (voltage) gradient across the two coupling leads. This may have important implications for novel thermoelectric applications of quantum dots. The support from the Natural Science Foundation of China (Grants No. 21033008, No. 21233007, No. 21303175, and No. 21322305) and the Strategic Priority Research Program (B) of the CAS (XDB01020000) is gratefully appreciated.

  2. Carbon "Quantum" Dots for Fluorescence Labeling of Cells.

    Science.gov (United States)

    Liu, Jia-Hui; Cao, Li; LeCroy, Gregory E; Wang, Ping; Meziani, Mohammed J; Dong, Yiyang; Liu, Yuanfang; Luo, Pengju G; Sun, Ya-Ping

    2015-09-02

    The specifically synthesized and selected carbon dots of relatively high fluorescence quantum yields were evaluated in their fluorescence labeling of cells. For the cancer cell lines, the cellular uptake of the carbon dots was generally efficient, resulting in the labeling of the cells with bright fluorescence emissions for both one- and two-photon excitations from predominantly the cell membrane and cytoplasm. In the exploration on labeling the live stem cells, the cellular uptake of the carbon dots was relatively less efficient, though fluorescence emissions could still be adequately detected in the labeled cells, with the emissions again predominantly from the cell membrane and cytoplasm. This combined with the observed more efficient internalization of the same carbon dots by the fixed stem cells might suggest some significant selectivity of the stem cells toward surface functionalities of the carbon dots. The needs and possible strategies for more systematic and comparative studies on the fluorescence labeling of different cells, including especially live stem cells, by carbon dots as a new class of brightly fluorescent probes are discussed.

  3. Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kushwaha, Manvir S. [Department of Physics and Astronomy, Rice University, P.O. Box 1892, Houston, TX 77251 (United States)

    2014-12-15

    Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes) – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorption in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing) the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots: resulting into a blue (red) shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower) magneto-optical transitions survive even in the extreme instances. However, the intra-Landau level

  4. Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

    Directory of Open Access Journals (Sweden)

    Manvir S. Kushwaha

    2014-12-01

    Full Text Available Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorption in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding the size of the quantum dots: resulting into a blue (red shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower magneto-optical transitions survive even in the extreme instances. However, the intra

  5. Computer-automated tuning of semiconductor double quantum dots into the single-electron regime

    Science.gov (United States)

    Baart, T. A.; Eendebak, P. T.; Reichl, C.; Wegscheider, W.; Vandersypen, L. M. K.

    2016-05-01

    We report the computer-automated tuning of gate-defined semiconductor double quantum dots in GaAs heterostructures. We benchmark the algorithm by creating three double quantum dots inside a linear array of four quantum dots. The algorithm sets the correct gate voltages for all the gates to tune the double quantum dots into the single-electron regime. The algorithm only requires (1) prior knowledge of the gate design and (2) the pinch-off value of the single gate T that is shared by all the quantum dots. This work significantly alleviates the user effort required to tune multiple quantum dot devices.

  6. Electron Spin Dephasing and Decoherence by Interaction with Nuclear Spins in Self-Assembled Quantum Dots

    Science.gov (United States)

    Lee, Seungwon; vonAllmen, Paul; Oyafuso, Fabiano; Klimeck, Gerhard; Whale, K. Birgitta

    2004-01-01

    Electron spin dephasing and decoherence by its interaction with nuclear spins in self-assembled quantum dots are investigated in the framework of the empirical tight-binding model. Electron spin dephasing in an ensemble of dots is induced by the inhomogeneous precession frequencies of the electron among dots, while electron spin decoherence in a single dot arises from the inhomogeneous precession frequencies of nuclear spins in the dot. For In(x)Ga(1-x) As self-assembled dots containing 30000 nuclei, the dephasing and decoherence times are predicted to be on the order of 100 ps and 1 (micro)s.

  7. Photoluminescent carbon dots synthesized by microwave treatment for selective image of cancer cells.

    Science.gov (United States)

    Yang, Xudong; Yang, Xue; Li, Zhenyu; Li, Shouying; Han, Yexuan; Chen, Yang; Bu, Xinyuan; Su, Chunyan; Xu, Hong; Jiang, Yingnan; Lin, Quan

    2015-10-15

    In this work, a simple, low-cost and one-step microwave approach has been demonstrated for the synthesis of water-soluble carbon dots (C-dots). The average size of the resulting C-dots is about 4 nm. From the photoluminescence (PL) measurements, the C-dots exhibit excellent biocompatibility and intense PL with the high quantum yield (QY) at Ca. 25%. Significantly, the C-dots have excellent biocompatibility and the capacity to specifically target the cells overexpressing the folate receptor (FR). These exciting results indicate the as-prepared C-dots are promising biocompatible probe for cancer diagnosis and treatment.

  8. Imaging of Bacterial and Fungal Cells Using Fluorescent Carbon Dots Prepared from Carica papaya Juice.

    Science.gov (United States)

    Kasibabu, Betha Saineelima B; D'souza, Stephanie L; Jha, Sanjay; Kailasa, Suresh Kumar

    2015-07-01

    In this paper, we have described a simple hydrothermal method for preparation of fluorescent carbon dots (C-dots) using Carica papaya juice as a precursor. The synthesized C-dots show emission peak at 461 nm with a quantum yield of 7.0 %. The biocompatible nature of C-dots was confirmed by a cytotoxicity assay on E. coli. The C-dots were used as fluorescent probes for imaging of bacterial (Bacillus subtilis) and fungal (Aspergillus aculeatus) cells and emitted green and red colors under different excitation wavelengths, which indicates that the C-dots can be used as a promising material for cell imaging.

  9. Ground State Transitions in Vertically Coupled Four-Layer Single Electron Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    WANG An-Mei; XIE Wen-Fang

    2005-01-01

    We study a four-electron system in a vertically coupled four-layer quantum dot under a magnetic field by the exact diagonalization of the Hamiltonian matrix. We find that discontinuous ground-state energy transitions are induced by an external magnetic field. We find that dot-dot distance and electron-electron interaction strongly affect the low-lying states of the coupled quantum dots. The inter-dot correlation leads to some sequences of possible disappearances of ground state transitions, which are present for uncoupled dots.

  10. Ground State Transitions in Vertically Coupled Four-Layer Single Electron Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    WANGAn-Mei; XIEWen-Fang

    2005-01-01

    We study a four-electron system in a vertically coupled four-layer quantum dot under a magnetic field by the exact diagonalization of the Hamiltonian matr/x. We find that discontinuous ground-state energy transitions are induced by an external magnetic field. We find that dot-dot distance and electron-electron interaction strongly affect the low-lying states of the coupled quantum dots. The inter-dot correlation leads to some sequences of possible disappearances of ground state transitions, which are present for uncoupled dots.

  11. Observation of trapping and release of carriers in InGaAs/GaAs quantum dots by ultrafast THz spectroscopy

    DEFF Research Database (Denmark)

    Porte, Henrik; Jepsen, Peter Uhd; Daghestani, Nart;

    2009-01-01

    Depending on the photoexcitation wavelength, we either observe the trapping of the free carriers into quantum dots, or release of carriers from quantum dot ground state into conducting states of the quantum dot sample.......Depending on the photoexcitation wavelength, we either observe the trapping of the free carriers into quantum dots, or release of carriers from quantum dot ground state into conducting states of the quantum dot sample....

  12. The ten deadly mistakes of wanna-dots.

    Science.gov (United States)

    Kanter, R M

    2001-01-01

    Increasingly, it seems, there are just two types of companies left in the world: dot-coms, born on the Internet, and "wanna-dots," established organizations that are seeking to incorporate the Internet into their businesses. Some wanna-dots manage the deep mind-shift required to cross the digital divide. These are the pacesetters--the first movers and fast followers that exhibit organizational curiosity and the desire to innovate. But most wanna-dots are laggards; they don't rise to the challenge with the same resolve. In a global research effort involving more than 800 companies, the author uncovered so many wanna-dots making the same kinds of mistakes that it almost seemed they were following a How Not to Change guide. In this article, Kanter creates just such a guide, offering ten pieces of antiadvice that expose the tendency of wanna-dots to make only cosmetic changes when deep transformation is required. Beyond delineating what not to do, Kanter serves up two examples of wanna-dots that got it right. First, Williams-Sonoma, which successfully made up for a slow start to create a strong Web presence. Second, Honeywell, a pacesetter led by e-believers from the start, which still found the road to the Web a challenging one. For companies not born digital, the fundamental problem is change. And the real place to look for change is not on the Internet but inside your company--at your own organizational culture and your attitude toward change.

  13. Detection of CdSe quantum dot photoluminescence for security label on paper

    Science.gov (United States)

    Isnaeni, Sugiarto, Iyon Titok; Bilqis, Ratu; Suseno, Jatmiko Endro

    2016-02-01

    CdSe quantum dot has great potential in various applications especially for emitting devices. One example potential application of CdSe quantum dot is security label for anti-counterfeiting. In this work, we present a practical approach of security label on paper using one and two colors of colloidal CdSe quantum dot, which is used as stamping ink on various types of paper. Under ambient condition, quantum dot is almost invisible. The quantum dot security label can be revealed by detecting emission of quantum dot using photoluminescence and cnc machine. The recorded quantum dot emission intensity is then analyzed using home-made program to reveal quantum dot pattern stamp having the word 'RAHASIA'. We found that security label using quantum dot works well on several types of paper. The quantum dot patterns can survive several days and further treatment is required to protect the quantum dot. Oxidation of quantum dot that occurred during this experiment reduced the emission intensity of quantum dot patterns.

  14. Phase diagram and low temperature scenario for a triangular triple dot system

    Science.gov (United States)

    Xiong, Yong-Chen; Wang, Wei-Zhong; Yang, Jun-Tao; Luo, Shi-Jun

    2016-01-01

    We present a triangular triple quantum dot (TTQD) system with two dots connected parallelly to one conduction lead, and investigate the phase diagram, the electric transport, and the temperature-dependent magnetic moment at half filling. When the hopping between two connected dots t12 = 0, and those between the connected dots and the side dot are symmetric t13 = t23, two connected dots form a spin triplet due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediated by the dot-lead coupling and/or the hopping t13 (t23). For t13 = 0, the triplet is partially screened by the conduction leads at low temperature. Both the connected dots and the side dot contribute to the magnetic moment of the system. For any definite t13, the triplet is totally screened by the conduction leads and the side dot, and the two-stage Kondo effect occurs. When t12 increases beyond a critical t12c, two connected dots form a spin singlet and decouple from the side dot. In this case, the Kondo peak is strongly suppressed, indicating zero conductance, and only the localized side dot contribute to the magnetic moment at low temperature. When t13 ≠ t23, we find a crossover as t12 increases, contrast to the first order transition of the symmetric case. Numerical renormalization group technique and physical arguments are used to obtain a detailed understanding of these problems.

  15. Detection of CdSe quantum dot photoluminescence for security label on paper

    Energy Technology Data Exchange (ETDEWEB)

    Isnaeni,, E-mail: isnaeni@lipi.go.id; Sugiarto, Iyon Titok [Research Center for Physics, Indonesian Institute of Science, Building 442 Puspiptek Serpong, South Tangerang, Banten, Indonesia 15314 (Indonesia); Bilqis, Ratu; Suseno, Jatmiko Endro [Department of Physics, Diponegoro University, Jl. Prof. Soedarto, Tembalang, Semarang, Indonesia 50275 (Indonesia)

    2016-02-08

    CdSe quantum dot has great potential in various applications especially for emitting devices. One example potential application of CdSe quantum dot is security label for anti-counterfeiting. In this work, we present a practical approach of security label on paper using one and two colors of colloidal CdSe quantum dot, which is used as stamping ink on various types of paper. Under ambient condition, quantum dot is almost invisible. The quantum dot security label can be revealed by detecting emission of quantum dot using photoluminescence and cnc machine. The recorded quantum dot emission intensity is then analyzed using home-made program to reveal quantum dot pattern stamp having the word ’RAHASIA’. We found that security label using quantum dot works well on several types of paper. The quantum dot patterns can survive several days and further treatment is required to protect the quantum dot. Oxidation of quantum dot that occurred during this experiment reduced the emission intensity of quantum dot patterns.

  16. Photodynamic antibacterial effect of graphene quantum dots.

    Science.gov (United States)

    Ristic, Biljana Z; Milenkovic, Marina M; Dakic, Ivana R; Todorovic-Markovic, Biljana M; Milosavljevic, Momir S; Budimir, Milica D; Paunovic, Verica G; Dramicanin, Miroslav D; Markovic, Zoran M; Trajkovic, Vladimir S

    2014-05-01

    Synthesis of new antibacterial agents is becoming increasingly important in light of the emerging antibiotic resistance. In the present study we report that electrochemically produced graphene quantum dots (GQD), a new class of carbon nanoparticles, generate reactive oxygen species when photoexcited (470 nm, 1 W), and kill two strains of pathogenic bacteria, methicillin-resistant Staphylococcus aureus and Escherichia coli. Bacterial killing was demonstrated by the reduction in number of bacterial colonies in a standard plate count method, the increase in propidium iodide uptake confirming the cell membrane damage, as well as by morphological defects visualized by atomic force microscopy. The induction of oxidative stress in bacteria exposed to photoexcited GQD was confirmed by staining with a redox-sensitive fluorochrome dihydrorhodamine 123. Neither GQD nor light exposure alone were able to cause oxidative stress and reduce the viability of bacteria. Importantly, mouse spleen cells were markedly less sensitive in the same experimental conditions, thus indicating a fairly selective antibacterial photodynamic action of GQD.

  17. Advancing colloidal quantum dot photovoltaic technology

    Science.gov (United States)

    Cheng, Yan; Arinze, Ebuka S.; Palmquist, Nathan; Thon, Susanna M.

    2016-06-01

    Colloidal quantum dots (CQDs) are attractive materials for solar cells due to their low cost, ease of fabrication and spectral tunability. Progress in CQD photovoltaic technology over the past decade has resulted in power conversion efficiencies approaching 10%. In this review, we give an overview of this progress, and discuss limiting mechanisms and paths for future improvement in CQD solar cell technology.We briefly summarize nanoparticle synthesis and film processing methods and evaluate the optoelectronic properties of CQD films, including the crucial role that surface ligands play in materials performance. We give an overview of device architecture engineering in CQD solar cells. The compromise between carrier extraction and photon absorption in CQD photovoltaics is analyzed along with different strategies for overcoming this trade-off. We then focus on recent advances in absorption enhancement through innovative device design and the use of nanophotonics. Several light-trapping schemes, which have resulted in large increases in cell photocurrent, are described in detail. In particular, integrating plasmonic elements into CQD devices has emerged as a promising approach to enhance photon absorption through both near-field coupling and far-field scattering effects. We also discuss strategies for overcoming the single junction efficiency limits in CQD solar cells, including tandem architectures, multiple exciton generation and hybrid materials schemes. Finally, we offer a perspective on future directions for the field and the most promising paths for achieving higher device efficiencies.

  18. Multiplexed modular genetic targeting of quantum dots.

    Science.gov (United States)

    Saurabh, Saumya; Beck, Lauren E; Maji, Suvrajit; Baty, Catherine J; Wang, Yi; Yan, Qi; Watkins, Simon C; Bruchez, Marcel P

    2014-11-25

    While DNA-directed nanotechnology is now a well-established platform for bioinspired nanoscale assembly in vitro, the direct targeting of various nanomaterials in living biological systems remains a significant challenge. Hybrid biological systems with integrated and targeted nanomaterials may have interesting and exploitable properties, so methods for targeting various nanomaterials to precise biological locations are required. Fluorescence imaging has benefited from the use of nanoparticles with superior optical properties compared to fluorescent organic dyes or fluorescent proteins. While single-particle tracking (SPT) in living cells with genetically encoded proteins is limited to very short trajectories, the high photon output of genetically targeted and multiplexed quantum dots (QDs) would enable long-trajectory analysis of multiple proteins. However, challenges with genetic targeting of QDs limit their application in these experiments. In this report, we establish a modular method for targeting QD nanoparticles selectively to multiple genetically encoded tags by precomplexing QD-streptavidin conjugates with cognate biotinylated hapten molecules. This approach enables labeling and SPT of multiple genetically encoded proteins on living cells at high speed and can label expressed proteins in the cytosol upon microinjection into living cells. While we demonstrate labeling with three distinct QD conjugates, the approach can be extended to other specific hapten-affinity molecule interactions and alternative nanoparticles, enabling precise directed targeting of nanoparticles in living biological systems.

  19. Optical orientation in self assembled quantum dots

    CERN Document Server

    Stevens, G C

    2002-01-01

    We examined Zeeman splitting in a series of ln sub x Ga sub ( sub 1 sub - sub x sub ) As/GaAs self assembled quantum dots (SAQD's) with different pump polarisations. All these measurements were made in very low external magnetic fields where direct determination of the Zeeman splitting energy is impossible due to its small value in comparison to the photoluminescence linewidths. The use of a technique developed by M. J. Snelling allowed us to obtain the Zeeman splitting and hence the excitonic g-factors indirectly. We observed a linear low field splitting, becoming increasingly non-linear at higher fields. We attribute this non-linearity to field induced level mixing. It is believed these are the first low field measurements in these structures. A number of apparent nuclear effects in the Zeeman splitting measurements led us onto the examination of nuclear effects in these structures. The transverse and oblique Hanie effects then allowed us to obtain the sign of the electronic g-factors in two of our samples,...

  20. Advancing colloidal quantum dot photovoltaic technology

    Directory of Open Access Journals (Sweden)

    Cheng Yan

    2016-06-01

    Full Text Available Colloidal quantum dots (CQDs are attractive materials for solar cells due to their low cost, ease of fabrication and spectral tunability. Progress in CQD photovoltaic technology over the past decade has resulted in power conversion efficiencies approaching 10%. In this review, we give an overview of this progress, and discuss limiting mechanisms and paths for future improvement in CQD solar cell technology.We briefly summarize nanoparticle synthesis and film processing methods and evaluate the optoelectronic properties of CQD films, including the crucial role that surface ligands play in materials performance. We give an overview of device architecture engineering in CQD solar cells. The compromise between carrier extraction and photon absorption in CQD photovoltaics is analyzed along with different strategies for overcoming this trade-off. We then focus on recent advances in absorption enhancement through innovative device design and the use of nanophotonics. Several light-trapping schemes, which have resulted in large increases in cell photocurrent, are described in detail. In particular, integrating plasmonic elements into CQD devices has emerged as a promising approach to enhance photon absorption through both near-field coupling and far-field scattering effects. We also discuss strategies for overcoming the single junction efficiency limits in CQD solar cells, including tandem architectures, multiple exciton generation and hybrid materials schemes. Finally, we offer a perspective on future directions for the field and the most promising paths for achieving higher device efficiencies.