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Sample records for c71 dot bien

  1. La Terre, notre bien commun

    Directory of Open Access Journals (Sweden)

    Arnaud Berthoud

    2008-03-01

    Full Text Available La Terre nous fait découvrir aujourd’hui une forme de responsabilité à l’égard de l’humanité toute entière. Quelle sorte de chose est donc la Terre lorsque nous usons de ce terme sous ses formes variées et que nous tentons de nous hisser au niveau de ce fait historique nouveau et de notre inquiétude à son sujet ? Je propose cette réponse générale : la Terre nous apparaît comme ce qui a été, est et sera toujours la chose la plus vaste à laquelle s’attache notre bien commun, parce qu’elle est le support, le fondement ou la base visible d’une vie que chacun éprouve intérieurement, selon un lien immédiat avec quelques semblables et comme le bien dont nous savons, comme le disait Maître Eckhart (1948, p.148, que « de tous les biens aucun ne nous est plus cher et plus désirable ». C’est cette réponse que je tente de développer en précisant successivement sous l’inspiration d’Aristote quelques traits relatifs au bien commun dont la Terre serait le support le plus vaste et sous l’inspiration biblique quelques remarques relatives au lien vivant qui nous attache à nos semblables et dont la Terre serait la base visible la plus claire. Je dirais alors que dans le premier cas la Terre est saisie comme un objet économique et que dans le second cas la Terre est saisie comme un objet religieux. J’essayerai dans la conclusion de rapporter ces deux types de propos l’un à l’autre.

  2. Electronic Structures and Optical Properties of Phenyl C71 Butyric Acid Methyl Esters

    Directory of Open Access Journals (Sweden)

    Cai-Rong Zhang

    2013-01-01

    Full Text Available Phenyl C71 butyric acid methyl ester (PC71BM has been adopted as electron acceptor materials in bulk heterojunction solar cells with relatively higher power conversion efficiency. The understanding of the mechanism and performance for the devices based upon PC71BM requires the information of conformations, electronic structures, optical properties, and so forth. Here, the geometries, IR and Raman, electronic structures, polarizabilities, and hyperpolarizabilities of PC71BM isomers are studied by using density functional theory (DFT; the absorption and excitation properties are investigated via time-dependent DFT with B3LYP, PBE0, and CAM-B3LYP functionals. The calculated results show that [6,6]PC71BM is more stable than [5,6]PC71BM due to the lower total energy. The vibrational modes of the isomers at IR and Raman peaks are quite similar. As to absorption properties, CAM-B3LYP functional is the suitable functional for describing the excitations of PC71BM because the calculated results with CAM-B3LYP functional agree well with that of the experiment. The analysis of transition configurations and molecular orbitals demonstrated that the transitions at the absorption maxima in UV/Vis region are localized π-π* transitions in fullerenes cages. Furthermore, the larger isotropic polarizability of PC71BM indicates that the response of PC71BM to applied external electric field is stronger than that of PC61BM, and therefore resulting into better nonlinear optical properties.

  3. Los bienes culturales como patrimonio educativo

    OpenAIRE

    Panciroli, Chiara

    2016-01-01

    Resumen: El patrimonio y los lugares que lo acogen, conservan, y exponen (entendiendo el museo como una referencia particular), se convierten progresivamente en espacios que revisten un papel estratégico, sobre todo en términos formativos. Se trata de una función formativa que se ha construido y se sigue definiendo con la historia de los museos y la individuación de los diferentes sentidos del bien objeto. El museo, considerado como el escenario final para la transmisión y comunicación del co...

  4. Biens communs, biens publics mondiaux et propriété. Introduction au dossier.

    Directory of Open Access Journals (Sweden)

    Bruno Boidin

    2008-03-01

    Full Text Available Nous proposons d’esquisser les différents enjeux liés au croisement des notions de biens communs et de propriété dans une économie mondialisée. Dans un premier temps un cadrage terminologique est présenté autour de termes juridiques qui font écho à des notions courantes dans l’analyse économique ; il s’agit de montrer l’intérêt d’articuler plusieurs disciplines autour de la question des liens entre biens communs et propriété. Dans un deuxième temps, quelques éclairages sont donnés sur les différentes conceptions des biens communs et des biens publics dits mondiaux ; on cherche ici à souligner à la fois la diversité, voire l’hétérogénéité des approches mais aussi les convergences entre celles-ci. Des perspectives sont ensuite initiées autour des contributions croisées que peuvent apporter les approches institutionnalistes, éthiques et d’économie politique.This article tackles the question of the links between the concepts of common goods and property in the context of globalisation. First we try to define theses different notions in the fields of law and economics. Our aim is to demonstrate the importance of pluridisciplinary approaches to analyse this links. Then we present various conceptions of common goods and public goods, to underline divergences and convergences. Finally we propose some perspectives offered by different heterodox approaches, in particular institutionalism, ethics and political economy.

  5. 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.

  6. Encuentro: François Houtart: "de los bienes comunes al bien común de la humanidad"

    OpenAIRE

    Houtart, François

    2014-01-01

    El presente artículo, relaciona la transcripción de la conferencia que Francois Hourtart ofreció en la Ciudad de Medellín Colombia, en el año 2015 cuyo tema desarrollado fue: "De los bienes comunes, al bien común de la humanidad". This article relates the transcript of the conference Hourtart Francois offered in the city of Medellin Colombia, in 2015 developed the theme was: "In the commons, at the common good of humanity"

  7. El mercado de bienes ilegales: el caso de la droga

    National Research Council Canada - National Science Library

    Becker, Gary S; Murphy, Kevin M; Grossman, Michael

    2006-01-01

    ... de las elasticidades. Cuando la demanda y la oferta no son muy elasticas, no paga hacer cumplir la prohibicion a menos que el valor social sea negativo. Tambien muestra que un impuesto monetario reduce la produccion e incrementa el precio mas que la represion optima del bien si fuera ilegal, aunque algunos productores vayan a la clandestinidad para evadir el im...

  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. Vivir bien, entre utopía y realidad

    Directory of Open Access Journals (Sweden)

    Kepa Artaraz

    2013-01-01

    Full Text Available Los paradigmas dominantes del bienestar siguen empeñándose en entender lo que este término significa. De igual manera, los diseñadores de políticas públicas ( policy makers se empeñan en hacer realidad las visiones dominantes de bienestar. este artículo examina la noción del bienestar adoptada recientemente por la constitución boliviana. se da gran relevancia a las nociones indígenas de «vivir bien», concepto que podría traducirse como «vivir bien en grupo» bajo los principios de sociabilidad y la promoción de valores de reciprocidad. adoptado por los bolivianos en su Constitución de 2009 como uno de los valores fundamentales, el artículo explora la contribución que puede hacer a las nociones de bienestar. sostiene que «vivir bien» constituye progreso en nuestras nociones de bienestar por el énfasis que hace el concepto en las relaciones armónicas, no solo en la sociedad, sino también con la naturaleza (la pachamama —nuestra Madre tierra—, brindando un nexo con la sostenibilidad que las actuales concepciones de bienestar a menudo no logran.

  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. Reconsiderando las tecnologías sociales como bienes comunes

    Directory of Open Access Journals (Sweden)

    Ariel Vercelli

    2010-05-01

    Full Text Available En este artículo se describen las relaciones que se plantean entre las regulaciones sobre bienes materiales e intelectuales y las “tecnologías sociales”. Para ello, se utilizan algunas herramientas teórico-metodológicas provenientes del análisis socio-técnico y se aprovechan desarrollos conceptuales referidos a la caracterización de los “bienes comunes”. El artículo es parte de un ejercicio teórico donde las tecnologías sociales se consideran como bienes comunes. Con ello se busca problematizar el carácter jurídico-político que pueden adquirir algunas tecnologías sociales y, a su vez, analizar posibles formas de privatización y apropiación que éstas podrían sufrir por parte de corporaciones comerciales y Estados. In this article, the author describes relations proposed between the regulation of material and intellectual goods and the “social technologies.” To that end, theoretical-methodological tools from social-technical analysis are used, and conceptual developments related to the characterization of “common goods” are applied. The article is part of a theoretical exercise in which social technologies are taken to be common goods. For that purpose, the legal-political character that some social technologies may acquire is problematized, and, at the same time possible forms of privatization and appropriation that these might undergo by private business or the state are analyzed.

  13. SYSTÉMATIQUE DES VALEURS DE BIEN (ADVERBE) EN FRANCAIS CONTEMPORAIN

    OpenAIRE

    Peroz, Pierre

    1991-01-01

    We know that the adverb bien ("well" in English) varies in meaning depending on given contexts. However it will be out of place to stipulate that there are different sorts of bien. Bien always reveals the same operation whatever the context: the calculation of the relation between a given occurrence of a propriety P and a reference value p. The different values of bien constitute a system. Two principles underline all these values: firstly the subjective or temporal origin of p, secondly the ...

  14. El mercado de bienes ilegales: el caso de la droga

    Directory of Open Access Journals (Sweden)

    Becker , Gary S.

    2006-12-01

    Full Text Available Este artículo examina los costos de reducir el consumo de un bien declarando ilegal su producción y castigando a los productores ilegales. Las drogas son el ejemplo más destacado. Cuanto más inelástica es la demanda o la oferta, mayor es el incremento del costo social de reducir la producción con mayor represión. Así, el gasto público óptimo de capturar y condenar a los proveedores ilegales no sólo depende de la diferencia entre los valores social y privado del consumo sino también de las elasticidades. Cuando la demanda y la oferta no son muy elásticas, no paga hacer cumplir la prohibición a menos que el valor social sea negativo. También muestra que un impuesto monetario reduce la producción e incrementa el precio más que la represión óptima del bien si fuera ilegal, aunque algunos productores vayan a la clandestinidad para evadir el impuesto monetario. Los impuestos al consumo y las restricciones a las cantidades no son equivalentes cuando la represión tiene costos

  15. DOT's CAFE rulemaking analysis.

    Science.gov (United States)

    2013-02-13

    Presentation discusses what DOT needs to consider in setting CAFE standards. How DOT's use of the CAFE Compliance and Effects Modeling System helps to analyze potential CAFE Standards. How DOT might approach the next round of CAFE standards for model...

  16. PAC et environnement : les biens publics en agriculture

    OpenAIRE

    Desjeux, Yann; Dupraz, Pierre; Thomas, Alban

    2011-01-01

    Les réformes successives de la politique agricole commune (PAC) depuis les années 1990 ont progressivement introduit les questions environnementales dans ses objectifs. Cependant, la PAC reste une politique sectorielle d’adaptation de l’outil de production et de soutien au revenu agricole. Les mesures agri-environnementales (MAE) de la PAC constituent l’instrument le plus ciblé sur les contributions de l’agriculture à l’environnement, mais elles sont dotées d’un budget relativement modeste, s...

  17. 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;}

  18. Los bienes de consumo como mecanismo de mediacion de la reproduccion cultural de las mujeres negras

    National Research Council Canada - National Science Library

    Silva de Oliveira, Josiane; David Vieira, Francisco Giovanni

    2009-01-01

    .... Nuestro objetivo, en esta investigacion, es entender como las mujeres negras utilizan el consumo como mecanismo de reproduccion cultural, proveyendo de significados a los bienes consumidos para...

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

    OpenAIRE

    Mauricio G. Villena; Ericka Y Lafuente

    2013-01-01

    La pregunta básica de investigación detrás de este trabajo es cómo difiere la va-loración económica de un bien ambiental considerando beneficiarios circundantes(quienes viven cerca del bien en cuestión) y no circundantes (quienes habitan-do el país donde se encuentra el bien, viven en poblaciones distantes y por tantodisfrutan esporádicamente de los beneficios provistos por el bien ambiental). Enparticular, en este documento se valora económicamente el Bosque de Algarrobosde la comunidad de T...

  20. 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...

  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. Ciberciudadanía, cultura y bienes públicos

    Directory of Open Access Journals (Sweden)

    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.

  3. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    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......Reminiscence is a self-reflecting process on past events and experiences. Not only does it enable past experiences to be brought to light through talk, but it also creates an affective environment, which allows participants to explore and construct a representation of the self (Buchanan...... 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...

  4. Pluralismo y bien común en el derecho constitucional

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    Pablo Nuevo

    2004-01-01

    Full Text Available En el presente artículo, el profesor Pablo Nuevo analiza las consecuencias que el abandono de la doctrina del bien común tiene en el derecho constitucional, a partir del estudio de la incoporación de valores al ordenamiento jurídico que realiza la Constitución Española de 1978. Esta incorporación parecería dotar de contenido material a la Constitución, que pasa a estar al servicio de la dignidad de la persona y de los valores de justicia, libertad, igualdad y pluralismo político. No obstante esta positivación de un orden axiológico, a juicio de Nuevo, el entendiminiento que el Tribunal Constitucional ha realizado del valor pluralismo contribuye a debilitar el propio Estado constitucional pues el Tribunal, de la mano del principio democrático y de la soberanía popular, ha interpretado el valor pluralismo como relativismo, negando a los valores un fundamento más allá del consenso. Entender el pluralismo como igual legitimidad de toda representación del hombre y del mundo, que funda un derecho a seguir dicha concepción en todos los aspectos de la vida social, favorece que los postulados de la Constitución sean entendidos como significantes sin significado, debiendo éste ser construido a partir del principio mayoritario, lo que conduce tanto al debilitamiento de los derechos fundamentales, como a la progresiva erosión de las condiciones sociales en que puede favorecer el Estado constitucional. Como subraya el autor, el Estado moderno vive de presupuestos que no puede crear, pero sí en todo caso destruir. De igual manera, para el profesor el constitucionalismo liberal, pluralista e individualista de nuestros tiempos, carece de herramientas conceptuales para solucionar las aporías que plantea las sociedades occidentales de nuestro tiempo, que se debaten entre el miedo al Leviatán y la inseguridad de un mundo anómico. El autor sostiene que solo con una vuelta a la ley natural es posible ordenar la vida política de manera que

  5. 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.

  6. Repensando los bienes comunes: análisis socio-técnico sobre la construcción y regulación de los bienes comunes

    OpenAIRE

    Ariel Vercelli; Hernán Thomas

    2008-01-01

    El presente artículo analiza los bienes comunes desde una perspectiva socio-técnica. Puntualmente, invita a repensarlos en función de algunos cambios tecnológicos recientes. A partir de esta perspectiva es posible observar cómo los bienes comunes son parte de un proceso continuo de luchas, negociaciones y redefiniciones políticas entre diferentes grupos de actores. Analiza como estas luchas políticas son parte de un proceso de co-construcción entre el diseño tecnológico y las nuevas formas de...

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

    National Research Council Canada - National Science Library

    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...

  8. El bien vivir: ¿cuidado de la salud o proyecto vital? Segunda parte

    Directory of Open Access Journals (Sweden)

    Leonardo Viniegra Velázquez

    2016-07-01

    Se arguye acerca de la superioridad de proyectos vitales altruistas en la consecución del bien vivir comunitario, sobre los afanes centrados en la preservación y el cuidado de la salud que favorecen el individualismo, la pasividad y el statu quo. La búsqueda del “bien morir” es el mejor ejemplo de la influencia benéfica de este tipo de proyectos en el cuidado de la salud.

  9. 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.

  10. Une mesure différente du bien-être : l'indice du bonheur national ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Une mesure différente du bien-être : l'indice du bonheur national brut du Bhoutan 2010. La demande de mesures novatrices, mais rigoureuses, du bien-être national allant au-delà du produit national brut ne cesse de croître. ... Réglementation du marché du travail en Chine : politiques en matière de salaire minimum.

  11. Les femmes actives sur les marchés peuvent voir leur bien-être s ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    6 juin 2016 ... La participation des femmes aux marchés du bétail peut entraîner une amélioration de leur bien-être et de celui de leur famille. ... Les femmes actives sur les marchés peuvent voir leur bien-être s'améliorer ... Parmi les problèmes observés figure l'absence de droits à la terre, au travail et aux capitaux.

  12. [Influence of unilayered and multilayered liposomes containing fatty-acid complex Bien upon phagocyte activity in rat alveolar macrophages].

    Science.gov (United States)

    Bushmakina, I M; Martynova, M A; Kniazeva, E V

    2014-01-01

    The phagocyte activity of rat alveolar macrophages and their primary culture under the interaction with liposomes containing unsaturated fatty acid complex Bien has been studied in vitro. Quantitative dependence of the phagocyte number and phagocyte factor on the liposomal Bien concentration were estimated. Comparative analysis of the effects of multilayered and unilayered liposomes with Bien upon cell suspension has been carried out.

  13. 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.

  14. From DOT to Dotty

    CERN Multimedia

    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.

  15. La valorisation économique du bien-être animal : une application au cas du porc

    OpenAIRE

    Latouche, Karine

    2003-01-01

    L'adoption des directives européennes imposant la prise en compte du bien-être des animaux dans les élevages pose la question de la valeur monétaire accordée à l'attribut respect du bien-être d'un produit animal donné sur le marché. La définition du bien-être animal retenue dans ce travail est celle imposée par la réglementation européenne, à savoir le respect des animaux selon certains critères imposés dans les différents textes, indépendamment de toute conséquence sur le produit final. D'ab...

  16. Bien-être, perception et quotidien : une mise en perspective heuristique

    OpenAIRE

    Grésillon, Lucile

    2008-01-01

    Cet article présente une réflexion tirée d’un doctorat intitulé « Sentir Paris : bien-être et valeurs des lieux » qui avait pour objet de recherche de déterminer la valeur des lieux à partir du bien-être que les habitants y éprouvent. Le quotidien, espace-temps caractérisé par son ordinaire, est propice au bien-être mais il n’est pas sans l’amoindrir ni le conditionner. Malgré cette ambivalence, en quoi ce quotidien se révèle-t-il heuris­tique par rapport à cette recherche ? Le contexte scien...

  17. 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...

  18. 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.

  19. Hybrid Double Quantum Dots

    DEFF Research Database (Denmark)

    Sherman, D.; Yodh, J. S.; Albrecht, S. M.

    2016-01-01

    Epitaxial semiconductor-superconductor hybrid materials are an excellent basis for studying mesoscopic and topological superconductivity, as the semiconductor inherits a hard superconducting gap while retaining tunable carrier density. Here, we investigate double-quantum-dot devices made from InA...... that the individual dots host weakly hybridized Majorana modes....

  20. Synthesis of quantum dots

    Science.gov (United States)

    McDaniel, Hunter

    2017-10-17

    Common approaches to synthesizing alloyed quantum dots employ high-cost, air-sensitive phosphine complexes as the selenium precursor. Disclosed quantum dot synthesis embodiments avoid these hazardous and air-sensitive selenium precursors. Certain embodiments utilize a combination comprising a thiol and an amine that together reduce and complex the elemental selenium to form a highly reactive selenium precursor at room temperature. The same combination of thiol and amine acts as the reaction solvent, stabilizing ligand, and sulfur source in the synthesis of quantum dot cores. A non-injection approach may also be used. The optical properties of the quantum dots synthesized by this new approach can be finely tuned for a variety of applications by controlling size and/or composition of size and composition. Further, using the same approach, a shell can be grown around a quantum dot core that improves stability, luminescence efficiency, and may reduce toxicity.

  1. El CIESPAL cambió para bien mi visión profesional

    Directory of Open Access Journals (Sweden)

    Juan Carlos Peña Gutiérrez

    2010-09-01

    Full Text Available El autor es un becario del CIESPAL (1989 quien da cuenta pormenorizada de la extraordinaria experiencia que obtuvo en el Curso Taller sobre "Producción de Programas Informativos para la radio", cambiando para bien la visión profesional que le dio grandes satisfacciones en su natal Bolivia.

  2. El sumo bien kantiano: el objeto construído de la ley moral

    Directory of Open Access Journals (Sweden)

    Alonso Villarán

    2016-01-01

    Full Text Available El presente artículo tiene tres objetivos: a. compilar las críticas planteadas en contra del sumo bien kantiano (un mundo donde la virtud es premiada con felicidad; b. elaborar una revisión crítica de las respectivas defensas; y c. desarrollar una nueva defensa, con énfasis en el problema de derivación (según el cual el sumo bien no se deriva de la ley moral. Respecto al primero punto, el artículo muestra que son al menos cinco los problemas que amenazan la doctrina: heteronomía, derivación, imposibilidad, irrelevancia y dualismo. Respecto al segundo, el artículo revela que las múltiples defensas elaboradas en nombre del sumo bien son fuente, a su vez, de otros problemas, como los de incompletitud, ilusión, injusticia, deslealtad y escisión. Respecto al tercer y principal punto, y empezando por la derivación, el artículo propone ver al sumo bien como el objeto construido de la ley moral. Resuelto el problema de derivación, el artículo ofrece breves respuestas a los otros problemas en juego. El artículo también traduce por primera vez, del inglés al español, fragmentos de importantes publicaciones sobre el sumo bien.

  3. 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.

  4. Quantum dot molecules

    CERN Document Server

    Wu, Jiang

    2014-01-01

    This book reviews recent advances in the exciting and rapidly growing field of quantum dot molecules (QDMs). It offers state-of-the-art coverage of novel techniques and connects fundamental physical properties with device design.

  5. 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

  6. Dimensión social del tráfico ilícito de bienes culturales

    OpenAIRE

    García, Tania

    2012-01-01

    Cadena de involucrados en el TIBC. Huaqueros y coleccionistas. Régimen de tenencia de tierra y sitios arqueológicos. Colecciones arqueológicas registradas por el INPC. Blanqueo de bienes. Seguridad ciudadana y tráfico ilícito de bienes culturales. Universidad Tecnológica de El Salvador

  7. 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.

  8. Les dépenses Publiques : quel optimum pour un bien être social ?

    OpenAIRE

    Benloulou, Salim-badreddine

    2014-01-01

    L’objectif de ce travail étant de présenter un cadre d’analyse montrant la relation éventuellement existante entre les dépenses publiques et le bien-être social en Algérie. La présente étude comporte un cadre théorique ayant trait à la définition des concepts et outils de calculs et d’évaluation de l’indice du bien-être rapporté à l’Algérie. Globalement, les résultats montrent qu’il existe un lien positif et significatif entre l’augmentation des dépenses publiques et le b...

  9. Le point sur les indices du bien-être national | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    21 janv. 2011 ... Par exemple, il ne tient pas compte des biens échangés dans l'économie non structurée ou clandestine — un secteur de taille dans les pays en développement — ni de la valeur des services bénévoles, des stages non rémunérés, du travail des aidants à domicile et des travaux de bricolage.

  10. Libéralisation du commerce des biens et services TIC : enjeux et ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Libéralisation du commerce des biens et services TIC : enjeux et implications pour la mise en oeuvre de politiques publiques en Afrique de l'Ouest. En Afrique de l'Ouest, les entreprises du secteur privé des technologies d'information et de la communication (TIC) ont démontré leur capacité à créer des emplois et à stimuler ...

  11. 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.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Miltón Samuel Camelo

    2009-12-01

    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.

  14. 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.

  15. Double quantum dot memristor

    Science.gov (United States)

    Li, Ying; Holloway, Gregory W.; Benjamin, Simon C.; Briggs, G. Andrew D.; Baugh, Jonathan; Mol, Jan A.

    2017-08-01

    Memristive systems are generalizations of memristors, which are resistors with memory. In this paper, we present a quantum description of quantum dot memristive systems. Using this model we propose and experimentally demonstrate a simple and practical scheme for realizing memristive systems with quantum dots. The approach harnesses a phenomenon that is commonly seen as a bane of nanoelectronics, i.e., switching of a trapped charge in the vicinity of the device. We show that quantum dot memristive systems have hysteresis current-voltage characteristics and quantum jump-induced stochastic behavior. While our experiment requires low temperatures, the same setup could, in principle, be realized with a suitable single-molecule transistor and operated at or near room temperature.

  16. Hexagonal graphene quantum dots

    KAUST Repository

    Ghosh, Sumit

    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.

  17. 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

  18. 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.

  19. Efecto del TLC Colombia – Chile en la balanza comercial (bienes) de Colombia: 2010 – 2013

    OpenAIRE

    Urrutia Tinjaca, Sandra Marcela; Vargas Pulido, William Ernesto

    2016-01-01

    Determinando el efecto del Tratado de Libre Comercio Colombia – Chile, en el crecimiento de la balanza comercial (bienes) de Colombia, en el periodo comprendido entre 2010 – 2013, se evidenció que los dos países presentan sectores productivos similares. Las dos economías en la actualidad tienen TLC firmado con Estados Unidos y la Unión Europea, asimismo forman parte de grupos económicos como la ALADI. En este documento se analizó cómo ha sido el comportamiento de la economía colombiana, al ha...

  20. 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

  1. Nueve variaciones para un bastidor bien tensado : Fragmento, cuerpo y pintura en Ernesto Deira

    OpenAIRE

    Maddonni, Alejandra

    2014-01-01

    En el presente texto se reflexiona acerca de la producción del artista argentino Ernesto Deira (1928-1986) a la luz de algunas características que hacen al arte contemporáneo. Tomando como disparador el políptico Nueve variaciones para un bastidor bien tensado (1965), se presentan algunos de sus elementos constitutivos –el cuerpo fragmentado, cosificado y desmaterializado; la indeterminación, la repetición, la seriación, el exceso y el desplazamiento–, como poderosos antecedentes de lo que oc...

  2. El bien vivir: ¿cuidado de la salud o proyecto vital? Segunda parte

    OpenAIRE

    Leonardo Viniegra Velázquez

    2016-01-01

    El sentido de la vida, la razón profunda del anhelo de vivir y la motivación para actuar en consecuencia, es el antecedente del proyecto vital (PV). Se argumenta cómo la lucha por la dignidad es el verdadero derrotero de superación de la condición humana y el eje de PV que aspiran al bien vivir. El PV que se propone es una aventura cognitiva que trasciende el consumismo, el individualismo y la pasividad en la búsqueda de otro mundo hospitalario e incluyente, donde tenga viabilidad la super...

  3. 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.

  4. Bitcoin: Documentos electrónicos para el intercambio de bienes y servicios

    OpenAIRE

    García Alejo, Luis Antonio

    2016-01-01

    [ES] Al hablar de Bitcoin no se hace alusión simplemente a una única cosa, al bien digital como tal, sino que nos referimos también al protocolo de envío y recepción de mensajes, basado en Open Source, a la red P2P (Par- a- par) y las propias criptomonedas (Bitcoins). Su creador, bajo el seudónimo de Satoshi Nakamoto, pretendía crear un proyecto con un objetivo principal: que las transacciones económicas entre dos personas no necesiten de un organismo central o ningún tipo de intermediario. E...

  5. Adolescentes intelectualmente bien dotados. Una investigación en la provincia de Toledo.

    OpenAIRE

    Hume Figueroa, Miriam; Sánchez Núñez, María Trinidad

    2004-01-01

    Este artículo sintetiza los resultados de una investigación sobre identificación de alumnos intelectualmente bien dotados de 1º de E.S.O. en la provincia de Toledo, que comienza en mayo de 1993 y que todavía está en curso. Mediante el método de filtrado o screening aplicamos la prueba Matrices Progresivas de Raven a casi 6.000 alumnos del curso mencionado. Escogimos la franja de alumnos que se situaba muy por encima de la media, según los resultados de dicha prueba, para realizar un estudio m...

  6. El bien vivir: ¿cuidado de la salud o proyecto vital? Primera parte

    OpenAIRE

    Viniegra-Velázquez, Leonardo

    2016-01-01

    En este trabajo sobre del bien vivir —aspiración humana universal y fin último en el ideal de la atención a la salud— se confrontan dos opciones para su consecución: cuidado de la salud y proyecto vital. Se inicia con un recuento de las expresiones de la degradación humana en el mundo actual propiciada por las desigualdades sociales, cuya intensidad y omnipresencia revelan una quiebra civilizatoria. Con este marco se argumenta cómo la medicalización de la vida, que reduce el cuidado de la sal...

  7. La obsolescencia programada en el bien de consumo y la dinámica del mercado

    OpenAIRE

    Espeleta Rios, Ana Milena

    2017-01-01

    Las economías mundiales en proceso de recuperación, con grandes fábricas y una dotación mano de obra altamente productiva, demandaban del mercado un mayor nivel de consumo. Este entorno propició el cambio de foco económico hacia una sociedad de consumo. En este escenario se desarrolla la Obsolescencia Programada como una saludable insatisfacción en cuanto a hacer las cosas menos bien de lo que pueden hacerse con la intención de aumentar la rotación de los productos en mano de los consumidores...

  8. RedDots Replayed

    DEFF Research Database (Denmark)

    Kinnunen, Tomi; Sahidullah, Md; Falcone, Mauro

    2017-01-01

    the protection of text-dependent ASV systems from replay attacks in the face of variable recording and playback conditions. Derived from the re-recording of the original RedDots database, the effort is aligned with that in text-dependent ASV and thus well positioned for future assessments of replay spoofing...

  9. 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

  10. White dots do matter

    DEFF Research Database (Denmark)

    Soeken, Mathias; Thomsen, Michael Kirkedal

    2013-01-01

    Toffoli circuits. We also show how to use these rules to derive more complex formulas. The major difference compared to existing approaches is the use of negative controls (white dots), which significantly increases the algebraic strength. We show how existing optimisation approaches can be adapted...

  11. 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...

  12. Le facteur XII de la coagulation: bien plus qu’un stabilisant de la fibrine

    Science.gov (United States)

    Messaoudi, N.; Lamaalmi, F.; Chakour, M.; Belmekki, A.; Naji, M.

    2011-01-01

    Summary Les Auteurs considèrent le rôle du facteur XIII de la coagulation dans la cicatrisation. Identifié depuis 1923, le rôle du facteur XIII ou le facteur stabilisant de la fibrine dans la coagulation a été bien élucidé. Son rôle dans la cicatrisation suggéré dès 1960 est méconnu par les hématologistes et les médecins prenant en charge les brûlés. Les Auteurs se proposent de mettre la lumière sur ce rôle, qui reste encore mystérieux et mérite d’être élucidé. PMID:21991236

  13. 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.

  14. El bien vivir: ¿cuidado de la salud o proyecto vital? Primera parte

    Directory of Open Access Journals (Sweden)

    Leonardo Viniegra-Velázquez

    2016-03-01

    La influencia de la medicalización en el modo de vivir ha convertido la obsesión por estar sano y el horror a la enfermedad en un medio de control social al servicio del poder que mantiene y profundiza las desigualdades; de ahí su promoción incesante. Se arguye cómo esa preocupación por la salud, lejos de aproximar al bien vivir, introduce por senderos de angustia, inseguridad y desasosiego. Al final, se hacen consideraciones sobre los inconvenientes de que el cuidado de la salud polarice la atención y las energías vitales de los profesionales de la salud y de los usuarios de los servicios, y se descuide la responsabilidad ética, que atañe a todos, de la búsqueda de un mundo hospitalario e incluyente.

  15. 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.

  16. LA RESPONSABILIDAD DEL PRODUCTOR POR GARANTÍAS DE BIENES Y SERVICIOS EN EL DERECHO COLOMBIANO

    Directory of Open Access Journals (Sweden)

    Juan Carlos Villalba Cuéllar

    2013-01-01

    Full Text Available La responsabilidad del productor por la garantía de calidad e idoneidad de los productos se rige hoy en día como una subespecie de responsabilidad en materia de protección al consumidor que tiene unos matices especiales. El presente escrito aborda teóricamente la responsabilidad del productor por garantías de bienes y servicios con el fin de delimitar sus características y alcances, y además diferenciarla de algunas figuras tradicionales del derecho privado, tales como la obligación de saneamiento por vicios ocultos y la garantía de buen funcionamiento del Código de Comercio colombiano.

  17. 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

  18. 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.

  19. 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.

  20. Stochastic clustered-dot dithering

    Science.gov (United States)

    Ostromoukhov, Victor; Hersch, Roger D.

    1999-10-01

    A new technique for building stochastic clustered-dot screens is being proposed. A large dither matrix comprising thousands of stochastically laid out screen dots is constructed by first laying out the screen dot centers. Screen dot centers are obtained by placing discrete disks of a chosen radius at free cell locations when traversing the dither array cells according to either a discretely rotated Hilbert space-filling curve or a random space-filling curve. After Delauney triangulation of the screen dot centers, the maximal surface of each screen dot is computed and isointensity regions are created. This isointensity map is converted into an antialiased gray scale image, i.e., into an array of preliminary threshold values. These threshold values are renumbered to obtain the threshold values of the final dither threshold array. By changing the disk radius, the screen dot size can be adapted to the characteristics of particular printing devices. Larger screen dots may improve the one reproduction of printers having important dot gain.

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

    Directory of Open Access Journals (Sweden)

    Beatriz Brozzú

    2005-12-01

    Full Text Available 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.

  2. Le paysage dans l’action publique : du patrimoine au bien commun

    Directory of Open Access Journals (Sweden)

    Anne Sgard

    2010-09-01

    Full Text Available Le paysage est dorénavant partie prenante des politiques publiques locales, souvent affiché au cœur même du projet de territoire. Cependant le débat reste largement ouvert dès lors qu’il s’agit de préciser à quoi « sert le paysage » et de lui associer une/des valeurs particulières, susceptibles de porter et de légitimer la problématique paysagère au cours du montage du projet. Ce texte part du constat que deux termes sont de manière récurrente associés au paysage, le patrimoine et, plus récemment, le bien commun, et se propose d’interroger cette orientation du discours sur le paysage. La pratique et le cadre juridique français, tendent à enfermer le paysage dans un registre avant tout patrimonial, privilégiant une logique de protection. L’expression de bien commun pose question : est-ce un équivalent de patrimoine, une facilité de langage portée par la mode, ou un apport innovant qui permet de réinterroger la place du paysage dans le débat et les méthodes d’intervention? Revenant sur les cadres théoriques de la réflexion sur les biens communs et sur sa diffusion actuelle dans l’ensemble des sciences sociales et environnementales, ce texte cherchera à identifier ce qu’elle peut apporter à la compréhension de la place du paysage dans les projets, en mettant notamment l’accent sur la question de l’accessibilité et de la négociation.The landscape is now part of local public policies, often displayed at the very heart of territorial projects. But the debate remains wide open when it comes to specifying what should be the use of “landscape" and to determine with which particular value, in order to legitimize the thematic of landscape in the building of the territorial project. This text is based on the observation that two notions are consistently associated with landscape: heritage and, more recently, common good. We propose to examine the effect of these notions on the contemporary discourses

  3. Red Dot Basal Cell Carcinoma

    Science.gov (United States)

    2017-01-01

    Red dot basal cell carcinoma, a distinctive morphologic variant of basal cell carcinoma that presents as a small red macule (dot) or papule, is described on a woman’s thigh. A high index of suspicion is necessary to consider the diagnosis since the tumor mimics a telangiectasia or an angioma. PMID:28670359

  4. 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.

  5. Evolución de los bienes comunales en el siglo XV

    Directory of Open Access Journals (Sweden)

    José Luis MARTÍN MARTÍN

    2009-12-01

    Full Text Available En las sociedades donde predomina de manera abrumadora la dedicación agropecuaria, las grandes transformaciones de tipo demográfico, social o económico, deben reflejarse de modo claro en la organización del espacio. Parece por eso muy probable que los profundos cambios que se observan durante el siglo XV tengan su incidencia en aquellos elementos productivos más flexibles, que no estaban sujetos a una titularidad personal o familiar, sino en provecho amplio, abierto, de toda la colectividad. Los bienes comunales constituían una especie de reserva de la que ciudades, villas y aldeas disponían según las competencias que tuvieran asumidas, de acuerdo con la tipología y funciones que leyes y costumbres atribuían a cada una de ellas, y según lo permitiera el juego de necesidades y capacidad de decisión que se articulara en cada lugar. Por eso la relación entre ambos tipos de fenómenos no es directa, se desvía hacia otros sectores o aparece con manifestaciones distintas según momentos o zonas.

  6. 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.

  7. 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

  8. 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.

  9. ENAJENACIÓN DE BIENES COMUNALES Y COLONIZACIÓN RURAL EN REQUENA. SIGLO XVIII

    Directory of Open Access Journals (Sweden)

    Juan Piqueras Haba

    2010-01-01

    Full Text Available Durante el siglo XVIII tuvo lugar en el municipio de Requena un proceso de colonización agraria por establecimiento de familias sobre unos territorios hasta entonces prácticamente deshabitados. El poblamiento y la misma colonización fue hecha a expensas de los bienes omunales, dehesas y montes blancos, gestionados por el Concejo de la villa de Requena, cuyos responsables no sólo malvendieron y toleraron la usurpación particular de los terrenos oncejiles, sino que fueron parte interesada en la misma, hasta el punto de acaparar la mayor parte de las tierras baldías. Al mismo tiempo el reparto, la enajenación y la adquisición de las dehesas concejiles por varias docenas de colonos dieron origen a que sobre aquellas fértiles tierras se desarrollaran luego muchas de las aldeas que hoy componen el paisaje rural del término. En menos de un siglo el ayuntamiento quedó privado de más de 60.000 hectáreas, de las que unas 20.000 fueron ganadas para la agricultura por colonos labradores cuyo número aumentó de sólo 80 en 1667 a 161 en 1731 y a 752 en 1831.

  10. Interventional Audiology to Address Hearing Health Care Disparities: Oyendo Bien Pilot Study.

    Science.gov (United States)

    Marrone, Nicole; Ingram, Maia; Somoza, Maria; Jacob, Daisey Sánchez; Sanchez, Adriana; Adamovich, Stephanie; Harris, Frances P

    2017-05-01

    Interventional audiology, specifically community-based outreach, can connect people with the hearing health care system. Community-based participatory research methods were applied in two phases of research to: (1) investigate the needs of families affected by hearing loss in a rural Arizona community on the U.S.-Mexico border; and (2) evaluate an outreach program on hearing health. The needs assessment included interviews with persons with hearing loss and focus groups with family members and the greater community. The needs assessment revealed that despite perceived severity of hearing loss, help-seeking for audiologic care was limited due to barriers, stigma, and low self-efficacy. Results informed development of a community-based pilot study conducted as part of an academic-community partnership between audiology, public health, and community health workers of a federally qualified health center. An outreach program, Oyendo Bien (hearing wellness), a 5-week, Spanish-language health education program for older adults (n = 21) incorporated communication strategies and behavioral change techniques. Postprogram focus groups revealed increased self-efficacy and decreased stigma. After 1 year, 7 of 9 participants with hearing loss contacted for follow-up had sought some form of hearing-related health care. Future research should further investigate interventional audiology approaches to address health disparities.

  11. Établir le bien-fondé du libre accès à la recherche | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    « La recherche devrait être un bien public », affirme Erika Malich, titulaire d'une bourse de recherche du CRDI en 2016. « Peu importe à quel point elle est rigoureuse et peu importe l'importance des conclusions, la recherche ne parle pas d'elle-même. »

  12. 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

  13. 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.

  14. DOT Official County Highway Map

    Data.gov (United States)

    Minnesota Department of Natural Resources — The County Highway Map theme is a scanned and rectified version of the original MnDOT County Highway Map Series. The cultural features on some of these maps may be...

  15. Marvelous applications of quantum dots.

    Science.gov (United States)

    Cheki, M; Moslehi, M; Assadi, M

    2013-05-01

    Nanotechnology is developed to convert research, prevention, and treatment of cancer through the novel diagnostic imaging techniques and therapies. In particular, the imaging nanotechnology has gained substantial momentum in recent years. The main progress in nanotechnology has led to the production of novel fluorescent probes named quantum dots (QDs). Quantum dots develop a revolution in the molecular tagging processes within research, in vivo and in vitro studies. Due to unique physical and chemical features of QD probes, new possible techniques of early cancer detection and therapeutic management are being surveyed. Quantum dots have also dissolved many of the restrictions of organic fluorophores and are a talented option as a research tool. This review addresses on the present status of research, preclinical applications and also future visions of quantum dots.  

  16. PennDOT : fact book

    Science.gov (United States)

    2008-06-01

    PennDOT was created in 1970 when the former : Department of Highways was merged with transportation related : functions from the Departments of Revenue, : Commerce, Community Affairs and Military Affairs. With : an annual budget of about $5.4 billion...

  17. Implementace hry Dots and Boxes

    OpenAIRE

    Balko, Martin

    2010-01-01

    Title: Dots and Boxes implementation Author: Martin Balko Department: Department of Applied Mathematics Supervisor: RNDr. Ondřej Pangrác, Ph.D. Supervisor's email address: Abstract: The presented thesis deals with the analysis of a popular logical game Dots and Boxes and its generalized versions. It focuses on the different methods and algorithms of opponent's artificial intelligence. The result of the work is implementation of the generalized version of this game in w...

  18. 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.

  19. Clinical application and evaluation of the Bien diagnostic criteria for Rasmussen encephalitis.

    Science.gov (United States)

    Olson, Heather E; Lechpammer, Mirna; Prabhu, Sanjay P; Ciarlini, Pedro D S C; Poduri, Annapurna; Gooty, Vasu D; Anjum, Muhammad W; Gorman, Mark P; Loddenkemper, Tobias

    2013-10-01

    The 2005 diagnostic criteria for Rasmussen encephalitis (RE) are based on seizures, clinical deficits, electroencephalography (EEG), neuroimaging, and pathology (Brain, 128, 2005, 451). We applied these criteria to patients evaluated for RE and epilepsy surgery controls to determine the sensitivity, specificity, and positive and negative predictive values (PPVs, NPVs) using pathology as the gold standard. We identified patients evaluated for RE based on medical records from 1993 to 2011. Fifty-two control patients with refractory epilepsy, unilateral magnetic resonance imaging (MRI) changes, and biopsies were selected from an epilepsy surgery database from matching years. Patients meeting all three of group A and/or two of three group B criteria were classified as meeting full criteria (positive). Patients not meeting full criteria were classified as negative. When available, pathology findings were re-reviewed with neuropathologists, and MRI imaging was re-reviewed with a neuroradiologist. RE was considered in the differential diagnosis for 82 patients, of whom 35 had biopsies. Twenty patients met full criteria (positive) without another explanation, including seven for whom biopsy was required to meet criteria and one in whom another etiology was identified. Two patients met full criteria but had another explanation. Thirty-five met partial criteria (negative), of whom 14 had another etiology identified. Twenty-five met no criteria (negative). The diagnostic criteria had a sensitivity of 81% with four false negatives (criteria-negative, biopsy-positive) when compared to pathology as a gold standard. Five false positives (criteria positive, biopsy negative) had identifiable alternate diagnoses. The 2005 Bien clinical diagnostic criteria for RE have reasonably high sensitivity and specificity and good clinical-pathologic correlation in most cases. We suggest modification of the criteria to allow inclusion of cases with well-described but less common features

  20. 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.

  1. Depuración doctrinal e idea del bien en el liberalismo político de John Rawls

    OpenAIRE

    Fernández Manzano, Juan Antonio

    2015-01-01

    Nos ocupamos de analizar si el empleo de una idea del bien en Rawls es compatible con la pretensión de elaborar una concepción reductivamente política, alejada de compromisos doctrinales. Para ello analizamos cuál es la idea del bien que Rawls em-plea, en qué contextos la utiliza y qué justificaciones aporta con el fin de averiguar si la pretensión de una reducción política es posible. El trabajo aporta argumentos para considerar que la noción de lo reductivamente político y la presunta depur...

  2. La idea de los bienes comunes en el sistema internacional: ¿renacimiento o extinción?

    Directory of Open Access Journals (Sweden)

    María-Cecilia Añaños

    2014-01-01

    Full Text Available La idea de los bienes comunes ha experimentado en los últimos años un renacimiento gracias a las investigaciones realizadas principalmente en las ciencias económicas, y a su presencia en creaciones intelectuales. Mas su existencia en el sistema internacional sigue siendo exigua y controvertida, sobre todo tratándose de espacios o recursos comunes globales que actualmente parecen someterse a las tendencias globales de privatización y comercialización. El presente trabajo se ocupará de esclarecer, en qué medida este sistema internacional reconoce la idea de los bienes comunes en los recursos globales y si cabe referirse a su renacimiento a este nivel.

  3. Stability of quantum dots in live cells

    Science.gov (United States)

    Zhu, Zheng-Jiang; Yeh, Yi-Cheun; Tang, Rui; Yan, Bo; Tamayo, Joshua; Vachet, Richard W.; Rotello, Vincent M.

    2011-12-01

    Quantum dots are highly fluorescent and photostable, making them excellent tools for imaging. When using these quantum dots in cells and animals, however, intracellular biothiols (such as glutathione and cysteine) can degrade the quantum dot monolayer, compromising function. Here, we describe a label-free method to quantify the intracellular stability of monolayers on quantum dot surfaces that couples laser desorption/ionization mass spectrometry with inductively coupled plasma mass spectrometry. Using this new approach we have demonstrated that quantum dot monolayer stability is correlated with both quantum dot particle size and monolayer structure, with appropriate choice of both particle size and ligand structure required for intracellular stability.

  4. Imaging and Manipulating Energy Transfer Among Quantum Dots at Individual Dot Resolution.

    Science.gov (United States)

    Nguyen, Duc; Nguyen, Huy A; Lyding, Joseph W; Gruebele, Martin

    2017-06-27

    Many processes of interest in quantum dots involve charge or energy transfer from one dot to another. Energy transfer in films of quantum dots as well as between linked quantum dots has been demonstrated by luminescence shift, and the ultrafast time-dependence of energy transfer processes has been resolved. Bandgap variation among dots (energy disorder) and dot separation are known to play an important role in how energy diffuses. Thus, it would be very useful if energy transfer could be visualized directly on a dot-by-dot basis among small clusters or within films of quantum dots. To that effect, we report single molecule optical absorption detected by scanning tunneling microscopy (SMA-STM) to image energy pooling from donor into acceptor dots on a dot-by-dot basis. We show that we can manipulate groups of quantum dots by pruning away the dominant acceptor dot, and switching the energy transfer path to a different acceptor dot. Our experimental data agrees well with a simple Monte Carlo lattice model of energy transfer, similar to models in the literature, in which excitation energy is transferred preferentially from dots with a larger bandgap to dots with a smaller bandgap.

  5. 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.

  6. Inter-dot coupling effects on transport through correlated parallel ...

    Indian Academy of Sciences (India)

    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. Keywords. Coupled quantum dots ...

  7. Transport through graphene quantum dots

    Science.gov (United States)

    Güttinger, J.; Molitor, F.; Stampfer, C.; Schnez, S.; Jacobsen, A.; Dröscher, S.; Ihn, T.; Ensslin, K.

    2012-12-01

    We review transport experiments on graphene quantum dots and narrow graphene constrictions. In a quantum dot, electrons are confined in all lateral dimensions, offering the possibility for detailed investigation and controlled manipulation of individual quantum systems. The recently isolated two-dimensional carbon allotrope graphene is an interesting host to study quantum phenomena, due to its novel electronic properties and the expected weak interaction of the electron spin with the material. Graphene quantum dots are fabricated by etching mono-layer flakes into small islands (diameter 60-350 nm) with narrow connections to contacts (width 20-75 nm), serving as tunneling barriers for transport spectroscopy. Electron confinement in graphene quantum dots is observed by measuring Coulomb blockade and transport through excited states, a manifestation of quantum confinement. Measurements in a magnetic field perpendicular to the sample plane allowed to identify the regime with only a few charge carriers in the dot (electron-hole transition), and the crossover to the formation of the graphene specific zero-energy Landau level at high fields. After rotation of the sample into parallel magnetic field orientation, Zeeman spin splitting with a g-factor of g ≈ 2 is measured. The filling sequence of subsequent spin states is similar to what was found in GaAs and related to the non-negligible influence of exchange interactions among the electrons.

  8. Ultrafast spectroscopy of quantum dots

    CERN Document Server

    Foo, E

    2001-01-01

    exchange-correlation interactions among the confined carriers inside the dots are suggested to be responsible. A density functional calculation for BGR of the ground state transition shows good agreement with our experimental results, especially in the high dot occupancy regime. Many-particle state scattering gives rise to large homogeneous spectral broadening of the PL peaks, from which an intradot relaxation time approx 300 fs is estimated. This observation supports the results obtained by direct excitation of carriers within the QDs. Femtosecond time-resolved photoluminescence measured by frequency up-conversion has been used to investigate carrier dynamics in InAs/GaAs self-assembled quantum dots (QDs). Our results reveal ultrafast carrier relaxation and sequential state filling. Carrier relaxation is proposed to occur by Auger-type processes, and the sequential state filling suggests that intradot relaxation is much faster than carrier capture from the InAs wetting layer. Measurements obtained by direct ...

  9. 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....

  10. 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

  11. 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.

  12. 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

  13. 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

  14. La idea de los bienes comunes en el sistema internacional: ¿renacimiento o extinción?

    OpenAIRE

    María Cecilia, Añaños Meza

    2014-01-01

    La idea de los bienes comunes ha experimentado en los últimos años un renacimiento gracias a las investigaciones realizadas principalmente en las ciencias económicas, y a su presencia en creaciones intelectuales. Mas su existencia en el sistema internacional sigue siendo exigua y controvertida, sobre todo tratándose de espacios o recursos comunes globales que actualmente parecen someterse a las tendencias globales de privatización y comercialización. El presente trabajo se ocupará de esclarec...

  15. La transmisión de la propiedad en la ejecución forzosa sobre bienes inmuebles

    OpenAIRE

    Murga Fernández, Juan Pablo

    2015-01-01

    La tesis doctoral tiene por objeto el análisis de los todos los problemas suscitados por la transmisión de la propiedad en el marco de los procesos de ejecución forzosa sobre bienes inmuebles. El proceso de ejecución forzosa constituye una pieza clave en el conjunto del Derecho de obligaciones, ya que a través del mismo se consigue la efectiva satisfacción de los derechos de crédito que puedan verse eventualmente lesionados, cristalizando de este modo el esencial principio de la responsabilid...

  16. El bien jurídico protegido en los delitos urbanísticos. Una propuesta de lege ferenda

    OpenAIRE

    Martín Pardo, Antonio

    2015-01-01

    El presente trabajo de investigación tiene por objeto el intento de realizar una propuesta convincente de bien jurídico protegido en el ámbito de los delitos urbanísticos. Dicha propuesta se realiza, como señala el título, desde una perspectiva de lege ferenda y, por tanto, desligada en un principio del concreto tenor literal de los tipos existentes en el Código penal. En el ámbito que nos ocupa, el de la ordenación territorial y el urbanismo hace ya veinte años que existen estos delitos ...

  17. Los propios y bienes de comunidad en la provincia de Tlaxcala durante la aplicacion de las Reformas Borbonicas, 1787-1804

    National Research Council Canada - National Science Library

    Bustamante Lopez, Carlos

    2010-01-01

    El articulo analiza a traves de los bienes propios y de comunidad en la provincia de tlaxcala, cual fue el impacto que en dicho patrimonio del cabildo indio y de los pueblos, respectivamente, tuvieron...

  18. Hyperdense dots mimicking microcalcifications : Mammographic findings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Hyeon; Park, Jeong Mi; Goo, Hyun Woo; Bang, Sun Woo [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    1996-12-01

    To differentiate fine hyperdense dots mimicking microcalcifications from true microcalcifications on mammography. Mammograms showing hyperdense dots in ten patients (mean age, 59 years) were evaluated. Two radiologists were asked to differentiate with the naked eye the hyperdense dots seen on ten mammograms and proven microcalcifications seen on ten mammograms. Densitometry was also performed for all lesions and the contrast index was calculated. The shape and distribution of the hyperdense dots were evaluated and enquires were made regarding any history of breast disease and corresponding treatment. Biopsies were performed for two patients with hyperdense dots. Two radiologists made correct diagnoses in 19/20 cases(95%). The contrast index was 0.10-0.88 (mean 0.58) for hyperdense dots and 0.02-0.45 (mean 0.17) for true microcalcifications. The hyperdense dots were finer and homogeneously rounder than the microcalcifications. Distribution of the hyperdense dots was more superficial in subcutaneous fat (seven cases) and subareolar area (six cases). All ten patients with hyperdense dots had history of mastitis and abscesses and had been treated by open drainage (six cases) and/or folk remedy (four cases). In eight patients, herb patches had been attached. Biopsies of hyperdense dots did not show any microcalcification or evidence of malignancy. These hyperdense dots were seen mainly in older patients. Their characteristic density, shape, distribution and clinical history makes differential diagnosis from true microcalcifications easy and could reduce unnecessary diagnostic procedures such as surgical biopsy.

  19. Optophononics with Coupled Quantum Dots

    Science.gov (United States)

    2014-02-18

    single InAs/GaAs quantum dots. Phys. Rev. B 68, 233301 (2003). 9. Bennemann, K.-H. & Ketterson, J. B. (eds), Superconductivity : Conventional and...superlattices. Science 338, 935–939 (2012). 17. Kim, J.-H. et al. Coherent phonons in carbon nanotubes and graphene . Chem. Phys. 413, 55–80 (2013). 18

  20. 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

  1. 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.

  2. Polymer-coated quantum dots

    NARCIS (Netherlands)

    Tomczak, N.; Liu, Rongrong; Vancso, Gyula J.

    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

  3. 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,

  4. Silicon quantum dots: surface matters

    NARCIS (Netherlands)

    Dohnalová, K.; Gregorkiewicz, T.; Kůsová, K.

    2014-01-01

    Silicon quantum dots (SiQDs) hold great promise for many future technologies. Silicon is already at the core of photovoltaics and microelectronics, and SiQDs are capable of efficient light emission and amplification. This is crucial for the development of the next technological frontiers—silicon

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. De Bienes de la Nación a Monumentos nacionales : Romanticismo y Patrimonio arquitectónico en Portugal

    Directory of Open Access Journals (Sweden)

    María Helena Maia

    2006-01-01

    Full Text Available Este artículo trata de la construcción de la noción de Patrimonio Arquitectónico en Portugal entre 1825 y 1880, período elegido por corresponder con aquél donde se define y consolida el proyecto de preservación romántico. De este modo, a partir del problema generado por la integración en los Bienes de la Nación de la voluminosa masa de bienes muebles e inmuebles, los «bienes nacionales», que hasta entonces habían estado mayoritariamente en poder de las Ordenes Religiosas y que incluían un elevado porcentaje de aquello que hoy se considera el patrimonio nacional. Se procura no solo comprender la evolución del cuadro patrimonial, sino también la de los discursos sobre el tema, la legislación promulgada y las prácticas efectivas de definición y salvaguardia de ese conjunto de edificios que, en este período, con el desarrollo de la consciencia patrimonial, se transforman en Monumentos Nacionales.This paper deals with the construction of the notion of Architectural Heritage in Portugal between 1825 and 1880, when the romantic «preservation project» was defined and consolidated. Having as a starting point the problem generated by the integration in the property of the Nation of a voluminous mass of properties, the so-called «national properties», that had until then been in the ownership of Religious Orders and include a high percentage of what is today considered our national heritage, we try not only to understand the evolution of the constitution of our architectural heritage, but also the several speeches on the subject, the promulgated legislation and the existing practices of definition and safeguard of this set of buildings that, at this time and due to the development of the consciousness of our heritage, were turned into National Monuments.

  10. 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

  11. Quantum Dot Light Emitting Diode

    Energy Technology Data Exchange (ETDEWEB)

    Keith Kahen

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  12. Quantum Dot Light Emitting Diode

    Energy Technology Data Exchange (ETDEWEB)

    Kahen, Keith

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  13. Entre los caminos A y B elijo el incierto C: El bien, el mal y los dilemas éticos

    OpenAIRE

    Cláudio, Victor

    2009-01-01

    En este artículo partimos de las definiciones de Bien y de Mal que nos ofrece la filosofía para la interpretación de los dilemas éticos en la práctica de la Psicología. Subrayamos que, como referencia en el proceso de decisión subyacente a la resolución de los dilemas éticos, los psicólogos tienen además del Código Deontológico nacional, el Meta-Código de Ética europeo, sus principios morales, éticos y sus emociones. Se discuten algunos dilemas éticos que tienen lugar en la práctica ...

  14. bien entendu’ vs ‘naturellement’: deux façons de désubjectiviser le dire

    Directory of Open Access Journals (Sweden)

    Elena Vladimirskaia

    2011-06-01

    Full Text Available Our study focuses on how the discourse markers (DM participate in the construction of discursive alterity. In our approach, the DM builds, for an assertion, a guarantor with its own semantics, which is the semantics of the lexical element constituting the basis of DM. Naturellement and bien entendu build referential value which ”disempowers” the speaker as a guarantor of his words. This desubjectivation is realized differently in each case analyzed, and is determined by the semantic identity of the DM. In this article we analyze how the DM build modulated commitment of the speaker in his role as the guarantor, convened by the semantics of the DM in the ”disresponsibilization” of the speaker as a guarantor of his own words.

  15. Los desafíos ambientales o la tragedia actual de los bienes comunes en la era del neoimperilismo

    Directory of Open Access Journals (Sweden)

    Gregorio Mesa Cuadros

    2006-01-01

    Full Text Available Este artículo desarrolla de manera preliminar algunos de los principales desafíos ambientales que aquejan a la sociedad contemporánea. Para ello, abordo la discusión desde tres momentos, el primero, como introducción, trata de presentar la tragedia actual de los bienes comunes en la era neoimperial y su más cercana idea: el econeocapitalismo; el segundo, algunos enunciados sobre varios de los principales desafíos ambientales ligados a la globalización econeocapitalista, y el tercero, a manera de conclusión, lo que nos queda: el papel de la academia y una nueva ética ambiental que interroga tanto a la política como al derecho.

  16. Quantum dots: lasers and amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Bimberg, Dieter; Ledentsov, Nikolai [Institut fuer Festkoerperphysik, PN5-2, Technische Universitaet Berlin, Hardenbergstrasse 36, 10623 (Germany)

    2003-06-25

    Continuous wave room-temperature output power of {approx} 3 W for edge emitters and of 1.2 mW for vertical-cavity surface-emitting lasers is realized for GaAs-based devices using InAs quantum dots (QDs) operating at 1.3 {mu}m. Characteristic temperatures up to 170 K below 330 K are realized. Simultaneously, differential efficiency exceeds 80% for these devices. Lasers emitting up to 12 W at 1140-1160 nm are useful as pump sources for Tm{sup 3+}-doped fibres for frequency up-conversion to 470 nm. Both types of lasers show transparency current densities of 6 A cm{sup -2} per dot layer, {eta}{sub int} = 98% and {alpha}{sub i} around 1.5 cm{sup -1}. Long operation lifetimes (above 3000 h at 50 deg C heatsink temperature at 1.5 W CW) and improved radiation hardness as compared to quantum well (QW) devices are manifested. Cut-off frequencies of about 10 GHz at 1100 nm and 6 GHz at 1300 nm and low {alpha} factors resulting in reduced filamentation and improved M{sup 2} values in single-mode operation are realized. Quantum dot semiconductor optical amplifiers (QD SOAs) demonstrate gain recovery times of 120-140 fs, 4-7 times faster than bulk/QW SOAs. The breakthrough became possible due to the development of self-organized growth in QD technology. (topical review)

  17. DISEÑO DE TARIFAS DE BIENES PÚBLICOS LOCALES. CONSIDERACIONES EN TORNO AL CASO DEL AGUA POTABLE

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Gómez Prado

    2013-10-01

    Full Text Available El recurso agua se constituye como un bien de primera necesidad, que no ha sido valorado de manera adecuada. Su valor no contempla los beneficios que genera en términos de bienestar, salud, económicos y ambientales, entre otros. No se explota de manera correcta, desperdiciándolo y contaminándolo indiscriminadamente.En últimas fechas se ha acentuado la discusión sobre la problemática de la disponibilidad del agua, y aunque en algunas regiones se presenta un escenario poco pesimista, es cierto que este recurso no se utiliza adecuadamente; es decir, el problema radica en su gestión y tarifación.El presente trabajo plantea una serie de propuestas metodológicas para asignar un valor tarifario económicamente eficiente al agua potable; se determinará el precio del recurso hídrico mediante la metodología de análisis de los costos reales de producción, intentando asignar un precio que permita solventar los costos medios de producción de largo plazo, así como utilidades que permitan reinversión ante incrementos futuros de la demanda sin afectar el precio.Valga señalar que la asignación de precios al recurso hídrico no se constituye en sí misma como una finalidad; se trata, más bien de la antesala del financiamiento del desarrollo local.

  18. 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.

  19. Barrier Engineered Quantum Dot Infrared Photodetectors

    Science.gov (United States)

    2015-06-01

    AFRL-RV-PS- AFRL-RV-PS- TR-2015-0111 TR-2015-0111 BARRIER ENGINEERED QUANTUM DOT INFRARED PHOTODETECTORS Sanjay Krishna Center for High Technology...2011 – 22 May 2012 4. TITLE AND SUBTITLE Barrier Engineered Quantum Dot Infrared Photodetectors 5a. CONTRACT NUMBER FA9453-12-1-0336 5b. GRANT...is Unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT To investigate barrier engineered designs to reduce the dark current in quantum dot infrared

  20. Today's DOT and the quest for more accountable organizational structures.

    Science.gov (United States)

    2005-12-01

    This study investigates the impact of DOT organizational structures on effective transportation planning and performance. A review of the 50 state DOT authorizing statutes and DOT organizational charts found minimal differences in organizational stru...

  1. LA TEORÍA GENERAL DE LA TRASMISIÓN DE BIENES Y EL REGISTRO DE LA PROPIEDAD EN ESPAÑA

    Directory of Open Access Journals (Sweden)

    Joaquín Sánchez Cebrián

    2008-01-01

    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 lo bienes, porque se establecen reglas genéricas aplicables con independencia de la naturaleza mueble o inmueble del bien; y junto a ellas, 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.

  2. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  3. Quantum dots for quantum information technologies

    CERN Document Server

    2017-01-01

    This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.

  4. Preparation of tin oxide quantum dots

    Science.gov (United States)

    Fauzi, N. F. S. M.; Kamarulzaman, N.; Kasim, M. F.; Chayed, N. F.; Aziz, N. D. A.

    2017-09-01

    Quantum dots are interesting nanostructures with have novel physical and chemical characteristics. It is not an easy task to obtain quantum dots because materials tend to agglomerate. In this work, SnO2 quantum dots have been successfully synthesized via a simple and low cost method which is the sol-gel method. Thermal analysis of the precursors were carried out using a Simultaneous Thermogravimetric Analyzer (STA). The annealed samples were characterized using X-Ray Diffraction (XRD) for phase studies. Finally, the crystallite size and morphology of tin oxide quantum dots were determined using Field Emission Scanning Electron Microscopy (FESEM).

  5. 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.

  6. Transmission and scarring in graphene quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang Liang; Lai Yingcheng; Ferry, David K; Akis, Richard; Goodnick, Stephen M [Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287 (United States)

    2009-08-26

    We study electronic transport in quantum-dot structures made of graphene. Focusing on the rectangular dot geometry and utilizing the non-equilibrium Green's function to calculate the transmission in the tight-binding framework, we find significant fluctuations in the transmission as a function of the electron energy. The fluctuations are correlated with the formation of quantum scarring states, or pointer states in the dot. Both enhancement and suppression of transmission have been observed. As the size of the quantum dot is increased, more scarring states can be formed, leading to stronger transmission or conductance fluctuations.

  7. Mixed-quantum-dot solar cells.

    Science.gov (United States)

    Yang, Zhenyu; Fan, James Z; Proppe, Andrew H; Arquer, F Pelayo García de; Rossouw, David; Voznyy, Oleksandr; Lan, Xinzheng; Liu, Min; Walters, Grant; Quintero-Bermudez, Rafael; Sun, Bin; Hoogland, Sjoerd; Botton, Gianluigi A; Kelley, Shana O; Sargent, Edward H

    2017-11-06

    Colloidal quantum dots are emerging solution-processed materials for large-scale and low-cost photovoltaics. The recent advent of quantum dot inks has overcome the prior need for solid-state exchanges that previously added cost, complexity, and morphological disruption to the quantum dot solid. Unfortunately, these inks remain limited by the photocarrier diffusion length. Here we devise a strategy based on n- and p-type ligands that judiciously shifts the quantum dot band alignment. It leads to ink-based materials that retain the independent surface functionalization of quantum dots, and it creates distinguishable donor and acceptor domains for bulk heterojunctions. Interdot carrier transfer and exciton dissociation studies confirm efficient charge separation at the nanoscale interfaces between the two classes of quantum dots. We fabricate the first mixed-quantum-dot solar cells and achieve a power conversion of 10.4%, which surpasses the performance of previously reported bulk heterojunction quantum dot devices fully two-fold, indicating the potential of the mixed-quantum-dot approach.

  8. 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...

  9. Los Actos de Administración Ordinaria y Extraordinaria de los bienes temporales de Institutos Religiosos. Del CIC17 al CIC83

    OpenAIRE

    Garceranth Ramos, S.J., P. Ismael Arturo

    2017-01-01

    La administración de los bienes temporales de la Iglesia viene tratada enel CIC83, Libro V, Título II, los cc. 1273 – 1289 y, en relación con losbienes de los Institutos Religiosos se deben tener en cuenta también loscc.636 – 638. El mismo tema de la administración de los bienes eclesiásticos se encuentra en el CIC17 en el Libro III, Parte VI, Título XXVIII, cc. 1518 – 1528 y, en cuanto a los bienes de los Institutos Religiosos, se aplican las normas canónicas del Libro II, Parte II, Título X...

  10. Au petit bonheur du dire : note sur le traitement du « bien dire » en analyse pragmatique du discours

    OpenAIRE

    Auchlin, Antoine

    2009-01-01

    Indépendamment des variations de goût auxquelles sont soumises les évaluations particulières de bien dire, c'est à leur dimension générique d'expérience langagière positive que l'article s'intéresse. Il propose de traiter le bien dire comme un cas particulier de réussite énonciative, déterminé par diverses contraintes, dont certaines (thématique, énonciative) sont brièvement discutées. L'article suppose que, en tant que cas de réussite énonciative, le bien dire fait l'objet d'une intuition pr...

  11. 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.

  12. La Propuesta de Directiva relativa a determinados aspectos de los contratos de compraventa en línea y otras ventas de bienes a distancia

    OpenAIRE

    Arroyo i Amayuelas, Esther

    2016-01-01

    [spa] Con la estrategia del Mercado Único Digital, la Comisión ha dejado atrás el CESL y, en su lugar, ha desdoblado sus contenidos en dos Propuestas de Directivas, una para el comercio online y a distancia de bienes y otra para el de contenidos digitales, que tienen carácter de máximos. Este artículo es un análisis de la Propuesta de Directiva relativa a determinados aspectos de los contratos de compraventa en línea y otras ventas a distancia de bienes. A pesar de las novedades que aporta, n...

  13. Les effets du management participatif sur le bien être, la productivité du travailleur et l'efficacité économique de l'entreprise.

    OpenAIRE

    Mahieu, Geoffrey

    2017-01-01

    Le présent travail s’intéresse à la problématique du management participatif à travers deux questions de recherche, à savoir : dans quelle mesure le management participatif influe-t-il sur le bien-être du travailleur et dans quelle mesure le management participatif influe-t-il sur la productivité des travailleurs et sur l’efficacité économique de l’entreprise ? En matière de bien-être, différentes thématiques sont exposées : la santé, la reconnaissance, le cadre relationnel, les conditions de...

  14. Competitividad de la industria de bienes de equipo de España y Alemania (1993-2008): ventaja absoluta y costes relativos

    OpenAIRE

    Boundi Chraki, Fahd

    2014-01-01

    El presente trabajo realizará un análisis comparativo del sector de bienes de equipo de España y Alemania, con el objeto de desentrañar los determinantes de la competitividad de esta industria. La hipótesis central es la siguiente: la industria de bienes de equipo de Alemania es más competitiva debido a su mayor productividad real y sus menores costes relativos. De este modo, se partirá de la teoría clásica y marxiana de la formación de los precios, y el modelo de las ventajas absolutas de An...

  15. L'évolution de la gestion des organisations et son impact sur la communication et le bien-être des travailleurs

    OpenAIRE

    Maron, Marie

    2017-01-01

    Le milieu de travail peut épanouir comme il peut engendrer certaines souffrances chez les sujets humains. De nombreux facteurs peuvent influencer le bien-être du travailleur: les individus (les collègues, la hiérarchie, les personnes externes à l’entreprise), les contraintes de travail, le sens du travail, l'exercice du pouvoir, etc. La santé au travail est devenue un enjeu important des relations sociales en entreprise. Cependant, quid de la dimension de la communication au sujet du bien-êtr...

  16. EL "PASS THROUGH" DEL TIPO DE CAMBIO EN LOS PRECIOS DE BIENES TRANSABLES Y NO TRANSABLES EN COSTA RICA

    Directory of Open Access Journals (Sweden)

    Jorge León Murillo

    2002-12-01

    Full Text Available Este trabajo estima el coeficiente de pass through del tipo de cambio en los precios de bienes transables y no transables en Costa Rica, para el corto y el largo plazo. Se utiliza el análisis de mínimos cuadrados para estimar los coeficientes, y se explora la dinámica de ajuste de los modelos utilizando el análisis de vectores auto regresivo. Dentro de los principales resultados del modelo se encontró un coeficiente de pass through para los bienes transables de 13% en el corto plazo y de 68% en el largo plazo; para los bienes no transables, el pass through es de 10% y 52% en el corto y largo plazo respectivamente. En el largo plazo se incluye un 7% de pass through indirecto producto del efecto de los precios de los transables en los de no transables. El estudio de la dinámica de ajuste de los precios de transables y no transables ante un choque del tipo de cambio mostró una duración de 17 y 27 meses respectivamente. Además se realizaron pruebas de causalidad de Granger y estabilidad del modelo. La primera mostró una relación de precedencia entre las variaciones de tipo de cambio e inflación, y entre inflación de los transables y de los no transables. La segunda evidencia un cambio estructural en el modelo de los no transables entre fines de 1995 e inicio de 1996. AbstractThis paper estimates short run and long run coefficients of exchange rate pass through in to the prices of tradable and non tradable goods in Costa Rica. The coefficients are estimated by OLS. A VAR analysis is conducted in order to estimate the dynamic process between exchange rate and inflation. Granger causality test and a stability test are conducted too. The short run pass through coefficients are 13% and 10%, for tradable and non tradable goods respectively and the long run coefficients are 68% and 52% in the same order. There is a second stage pass through of 7% included in the long run coefficient for non tradable goods. The dynamic analysis shows that the

  17. Adiabatic pumping through interacting quantum dots

    OpenAIRE

    Splettstoesser, Janine; Governale, Michele; König, Jürgen; Fazio, Rosario

    2005-01-01

    We present a general formalism to study adiabatic pumping through interacting quantum dots. We derive a formula that relates the pumped charge to the local, instantaneous Green function of the dot. This formula is then applied to the infinite-U Anderson model both for weak and strong tunnel-coupling strengths.

  18. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

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

    2002-01-01

    We have produced GaAs-based quantum-dot edge-emitting lasers operating at 1.16 mu m with record-low transparency current, high output power, and high internal quantum efficiencies. We have also realized GaAs-based quantum-dot lasers emitting at 1.3 mu m, both high-power edge emitters and low...

  19. Thick-shell nanocrystal quantum dots

    Science.gov (United States)

    Hollingsworth, Jennifer A [Los Alamos, NM; Chen, Yongfen [Eugene, OR; Klimov, Victor I [Los Alamos, NM; Htoon, Han [Los Alamos, NM; Vela, Javier [Los Alamos, NM

    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.

  20. 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

  1. 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...

  2. Effect of temperature on quantum dots

    Indian Academy of Sciences (India)

    MAHDI AHMADI BORJI

    2017-07-12

    Jul 12, 2017 ... applications. Quantum dot semiconductor lasers, due to the discrete density of states, low threshold current and temperature dependence, high optical gain and quan- tum efficiency and high modulation speed, ... elastic properties of neighbour materials, lattice mis- match, and geometry of the quantum dot ...

  3. Surround-gated vertical nanowire quantum dots

    NARCIS (Netherlands)

    Van Weert, M.H.M.; Den Heijer, M.; Van Kouwen, M.P.; Algra, R.E.; Bakkers, E.P.A.M.; Kouwenhoven, L.P.; Zwiller, V.

    2010-01-01

    We report voltage dependent photoluminescence experiments on single indium arsenide phosphide (InAsP) quantum dots embedded in vertical surround-gated indium phosphide (InP) nanowires. We show that by tuning the gate voltage, we can access different quantum dot charge states. We study the

  4. 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

  5. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 26; Issue 1. Many electron effects in ... Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as 'artificial atoms' by some, ... Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of ...

  6. 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...

  7. Exciton in closed and opened quantum dot

    Directory of Open Access Journals (Sweden)

    M.V.Tkach

    2007-01-01

    Full Text Available The theory of exciton spectrum in spherically symmetric states for the three- shell closed spherical quantum dot is proposed. The evolution of the exciton spectrum while varying the outer well thickness from zero (stationary spectrum of single closed spherical quantum dot to infinity (quasistationary spectrum of a single open spherical quantum dot is investigated. The mechanism of damping (semiwidth of quasistationary states due to the redistribution over the energy levels of probability of exciton location in the space of two inner shells of nanosystem is studied. It is shown that the three shell closed spherical quantum dot of a rather big thickness of the outer well quite sufficiently and exactly reflects the basic properties of the quasistationary exciton spectrum in a single open spherical quantum dot.

  8. Biocompatible Quantum Dots for Biological Applications

    Science.gov (United States)

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

    2011-01-01

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, sizetunable, 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. PMID:21276935

  9. 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Hole spin relaxation in quantum dots

    Science.gov (United States)

    Woods, L. M.; Reinecke, T. L.; Kotlyar, R.

    2004-03-01

    We present results for relaxation of the spin of a hole in a cylindrical quantum dot due to acoustic phonon assisted spin flips at low temperatures with an applied magnetic field. The hole dispersion is calculated by numerical diagonalization of the Luttinger Hamiltonian and applying perturbation theory with respect to the magnetic field, and the hole-phonon coupling is described by the Bir-Pikus Hamiltonian. We find that the decoherence time for hole spins for dots ≲20 nm is on the order of 10-8 s. This is several orders smaller than the decoherence time due to phonon assisted processes for electron spins in similar dots and is comparable to the total decoherence time of an electron spin in a quantum dot, which is controlled by the hyperfine interaction with nuclei. We obtain the dependence of the relaxation rate of the hole spin on dot size and hole mass.

  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. Las escuelas públicas rurales: entre el bien común y la exclusión

    Directory of Open Access Journals (Sweden)

    Rosa VÁZQUEZ RECIO

    2016-01-01

    Full Text Available Las escuelas rurales han desempeñado un papel muy importante en la historia de la educación, ya que han dado respuesta a una población que, por las condiciones de origen –contexto rural-, difícilmente hubieran tenido acceso a este bien común. Estas escuelas han sido subestimadas o, en todo caso, han sido consideradas escuelas de segunda clase respecto a las escuelas urbanas. Esta jerarquía responde al imaginario social de valorar más lo urbano que lo rural, y de esperar más –eficiencia social- de la población y escuela urbanas que de las rurales. A ello hay que añadir el impacto del discurso neoliberal en las escuelas rurales que, de un modo u otro, tiende a reforzar el determinismo social en pro de la conquista de la excelencia. Las políticas educativas actuales están poniendo al límite a las escuelas rurales, casi a la espera de su propia muerte. Pese a ello, su valor educativo no puede ser silenciado.

  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. 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.

  15. 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...

  16. 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.

  17. Ingreso y bienes de la población de edad media y avanzada en México*

    Science.gov (United States)

    Wong, Rebeca; Espinoza, Mónica

    2017-01-01

    Resumen El propósito de este artículo es resumir el monto y los tipos de ingreso que percibe y bienes que posee la población de edad media y avanzada en México. Se usan datos de la nueva Encuesta Nacional sobre Salud y Envejecimiento en México (Enasem) 2001, un estudio prospectivo de panel con representación nacional de las personas de 50 años de edad y más. Los resultados confirman las hipótesis formuladas: la distribución del ingreso y la riqueza están sesgadas en favor de ciertos grupos, sobre todo aquéllos con mayor educación; la composición de la riqueza se da principalmente en forma no financiera y el apoyo familiar es una fuente de ingreso importante; la asociación entre riqueza y salud es positiva en general, lo cual es consistente con la literatura internacional. Además se encuentra que la riqueza acumulada está distribuida más equitativamente que el ingreso, y se concluye que el indicador de riqueza ofrece una dimensión de análisis adicional al ingreso, con potencial para contribuir a los estudios del bienestar de la población en edad media y avanzada en México. PMID:29386981

  18. 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...

  19. 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.

  20. Quantum dots: lasers and amplifiers

    CERN Document Server

    Bimberg, D

    2003-01-01

    Continuous wave room-temperature output power of approx 3 W for edge emitters and of 1.2 mW for vertical-cavity surface-emitting lasers is realized for GaAs-based devices using InAs quantum dots (QDs) operating at 1.3 mu m. Characteristic temperatures up to 170 K below 330 K are realized. Simultaneously, differential efficiency exceeds 80% for these devices. Lasers emitting up to 12 W at 1140-1160 nm are useful as pump sources for Tm sup 3 sup + -doped fibres for frequency up-conversion to 470 nm. Both types of lasers show transparency current densities of 6 A cm sup - sup 2 per dot layer, eta sub i sub n sub t = 98% and alpha sub i around 1.5 cm sup - sup 1. Long operation lifetimes (above 3000 h at 50 deg C heatsink temperature at 1.5 W CW) and improved radiation hardness as compared to quantum well (QW) devices are manifested. Cut-off frequencies of about 10 GHz at 1100 nm and 6 GHz at 1300 nm and low alpha factors resulting in reduced filamentation and improved M sup 2 values in single-mode operation are ...

  1. 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...

  2. 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.

  3. Marca registrada ... reflexiones sobre el uso de las marcas comerciales, el consumo y la comercializacion de bienes en el mundo rural Argentino

    National Research Council Canada - National Science Library

    Lluch, Andrea

    2013-01-01

    ... de comercializacion y en la definicion de pautas de consumo en areas rurales. El articulo tambien analiza el impacto de estos procesos en las practicas y perfiles de los comerciantes minoristas, asi como en los sistemas de distribucion de bienes de consumo genericos (en particular, alimentos y bebidas).

  4. Inter-dot coupling effects on transport through correlated parallel ...

    Indian Academy of Sciences (India)

    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 ...

  5. 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.

  6. Investigation on DOT guided FMT: Whether the FMT image quality is robust to the priori DOT information?

    Science.gov (United States)

    Wang, Daifa; Bai, Jing

    2009-01-01

    The fluorescence molecular tomography (FMT) image quality could be improved significantly with reconstructed optical properties using diffuse optical tomography (DOT). However, different DOT algorithms and different constraint parameters usually lead to DOT images of obvious different image quality. In this paper, simulation experiment results demonstrate that the FMT image quality is robust to the great variation in DOT image quality.

  7. X-H{center_dot}{center_dot}{center_dot}{pi} and X-H{center_dot}{center_dot}{center_dot}N hydrogen bonds - Acetylene and hydrogen cyanide as proton acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Domagala, Malgorzata, E-mail: mdomagala@uni.lodz.pl [Department of Chemistry, University of Lodz, ul.Pomorska 149/153, 90-236 Lodz (Poland); Grabowski, Slawomir J., E-mail: slagra@uni.lodz.pl [Department of Chemistry, University of Lodz, ul.Pomorska 149/153, 90-236 Lodz (Poland)

    2009-09-18

    The hydrogen-bonded systems were considered where acetylene or hydrogen cyanide acts as a proton acceptor and different proton donating molecules are taken into account. The B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) calculations were performed for the systems considered; for HCN{center_dot}{center_dot}{center_dot}HF and C{sub 2}H{sub 2}{center_dot}{center_dot}{center_dot}HF complexes various levels of approximation were applied up to CCSD(T)/6-311++G(3df,3pd)//CCSD/6-311++G(3df,3pd). The Quantum Theory of 'Atoms in Molecules' (QTAIM) was also applied. It was found that {pi}-electrons of acetylene might act as the proton accepting centers and the found complex conformations are T-shaped ones. For hydrogen cyanide molecule the nitrogen atom acts as the proton acceptor center but not {pi}-electrons. The characteristics of the bond critical points were also considered for the analyzed interactions and numerous correlations were found between geometrical, energetic and QTAIM parameters. The decomposition of the interaction energy for the systems analyzed was also applied.

  8. Moment of inertia in elliptical quantum dots

    Science.gov (United States)

    Serra, Llorenç; Puente, Antonio; Lipparini, Enrico

    The moment of inertia of deformed quantum dots and its experimental relevance in relation to the dot spectroscopic features is theoretically investigated. A strong link to the low-energy orbital current mode that manifests in the magnetic dipole (M1) spectrum is stressed. The moment of inertia is obtained by solving the cranked Kohn-Sham equations within the local-spin-density approximation and the results discussed in comparison with the predictions of an analytical non-interacting model. The results as a function of deformation and size indicate that the existence of spin transitions in the dot ground state has an important effect on the moment of inertia.

  9. Odd triplet superconductivity in ultrasmall quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Stephan; Koenig, Juergen [Theoretische Physik, Universitaet Duisburg-Essen and CENIDE (Germany); Sothmann, Bjoern [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg (Germany)

    2016-07-01

    We report on the possibility to create odd frequency Cooper pairs in proximized interacting quantum dots attached to ferromagnetic leads. Spin blockade effects together with induced superconductivity allow electron pairs with same spin at different times to carry superconducting correlations. Besides the conventional finite singlet pairing amplitude on the dot, only odd frequency triplet pairing is possible here. This is in contrast to the double dot case. We demonstrate how the order parameter for odd-frequency triplet pairing as well as the differential Andreev conductance are influenced when tuning gate and/or bias voltages, the angle of magnetizations of the leads and the coupling to the nearby superconductor.

  10. Excitonic quasimolecules in nanosystems of quantum dots

    Science.gov (United States)

    Pokutnyi, Sergey I.

    2017-09-01

    The theory of excitonic quasimolecules (biexcitons) (formed of spatially separated electrons and holes) in a nanosystem that consists of semiconductor quantum dots synthesized in a borosilicate glass matrix is presented. It is shown that exciton quasimolecule formation is of a threshold character and is possible in nanosystem, if the spacing between the quantum dots surfaces is larger than a certain critical spacing. It was found that the binding energy of the singlet ground state of an exciton quasimolecule, consisting of two semiconductor quantum dots is a significant large values, larger than the binding energy of the biexciton in a semiconductor single crystal by almost two orders of magnitude.

  11. 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.

  12. Analysis list: DOT1L [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DOT1L Pluripotent stem cell + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/DOT1...L.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/DOT1L.5.tsv http://dbarchive.biosc...iencedbc.jp/kyushu-u/hg19/target/DOT1L.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/DOT1L.Plu

  13. Parallel carbon nanotube quantum dots and their interactions

    OpenAIRE

    Goss K.; Leijnse M.; Smerat S.; Wegewijs M.R.; Schneider C.M.; Meyer C

    2012-01-01

    We present quantum transport measurements of interacting parallel quantum dots formed in the strands of a carbon nanotube rope. In this molecular quantum dot system, transport is dominated by one quantum dot, while additional resonances from parallel side dots appear, which exhibit a weak gate coupling. This differential gating effect provides a tunability of the quantum dot system with only one gate electrode and provides control over the carbon nanotube strand that carries the current. By t...

  14. 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...

  15. Quaternary basin formation along the Dien Bien Phu fault zone and its neotectonic implication of northwestern Vietnam

    Science.gov (United States)

    Lai, K.; Chen, Y.; Chung, L.; Li, P.; Lam, D.

    2006-12-01

    The Dien Bien Phu (DBP) fault zone is one of the most conspicuous fault systems in the Indochina, extending over a distance of 150 km from Yunnan, China through the NW Vietnam into Laos. Recent Global Positioning system (GPS) data in China yielded that the present clockwise rotation of the southeastern Tibet block geologically corresponds to a region of left-lateral strike-slip faults, such as the Xianshuihe-Xiaojang fault and Dien Bien Phu fault, which appear to have accommodated clockwise rotation; whereas other GPS data from the network of Southeast Asia proposed that Indochina constitutes a stable tectonic block moving approximately east with respect to Eurasia. Although above GPS data show insignificant differential motion along DBP fault, active sinistral slip can be identified by clear geomorphic features, focal solutions and seismicity distribution in a NNE-striking zone parallel to the fault zone. Mapping of surface fault traces along the DBP fault zone using field outcrops, geophysical data, and geomorphologic features recognized by the aerial photos, SRTM, ASTER imageries and derived digital elevation models shows that virtually all active faults are reactivated structures sub-parallel to chronostratigraphic boundary. Along the DBF fault, three larger basins have been developed by different kinematics from north to south. The northern one at Chan Nua is rhomboidal in shape with a dimension of 2.5 km?.5 km, which can be defined as a pull-apart basin resulted by the strike-slip motion of the DBP fault. The fault configuration associated with the central one changes to two parallel sinistral and sinistral-normal faults forming a narrow subsiding weak zone (10 km?.5 km) filled with Quaternary deposits. The southern one is, however, created by that the main DBP fault bends the strike from NNE to NE where branches out a sinistral- normal fault with N-striking controlling a half-graben basin (17 km? km) filled with Quaternary deposits about 200 m in depth above

  16. Formations of magnetic vortices in a chain array of triangle Py dots and an isosceles triangle Py dot

    Science.gov (United States)

    Miyata, M.; Kiseki, K.; Yakata, S.; Wada, H.; Kimura, T.

    2012-04-01

    We have studied the magnetic domain structures in a magneto-statically-coupled chain array of the triangle dots and an isosceles triangle dot by means of magnetic force microscopy (MFM). Despite the strong magneto-static interaction in the chain array of the dots, each triangle dot takes a single vortex structure. The chirality of each dot is found to behave similarly to that for the isolated triangle dot. We also demonstrated that single-vortex and double-vortex structures with the desired chiralities can be stabilized in an isosceles triangle dot.

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

    Directory of Open Access Journals (Sweden)

    José Luis Torres Trespalacios

    2007-06-01

    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.

  18. Thermoelectric transport through quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Merker, Lukas Heinrich

    2016-06-30

    In this thesis the thermoelectric properties (electrical conductance, Seebeck coefficient and thermal conductance)of quantum dots described by the Anderson impurity model have been investigated by using the numerical renormalization group (NRG) method. In order to make accurate calculations for thermoelectric properties of quantum impurity systems, a number of recent developments and refinements of the NRG have been implemented. These include the z-averaging and Campo discretization scheme, which enable the evaluation of physical quantities on an arbitrary temperature grid and at large discretization parameter Λ and the full density matrix (FDM) approach, which allows a more accurate calculation of spectral functions and transport coefficients. The implementation of the z-averaging and Campo discretization scheme has been tested within a new method for specific heats of quantum impurities. The accuracy of this new method was established by comparison with the numerical solution of the Bethe-ansatz equations for the Anderson model. The FDM approach was implemented and tested within a new approach to the calculation of impurity contributions to the uniform susceptibilities. Within this method a non-negligible contribution from the ''environmental'' degrees of freedom needs to be taken into account to recover the correct susceptibility, as shown by comparison with the Bethe-ansatz approach. An accurate method to calculate the conductance of a quantum dot is implemented, enabling the extraction of the Fermi liquid scaling coefficients c{sub T} and c{sub B} to high accuracy, being able to verify the results of the renormalized super perturbation theory approach (within its regime of validity). The method was generalized to higher order moments of the local level spectral function. This, as well as reduction of the SU(2) code to the U(1) symmetry, enabled the investigation of the effect of a magnetic field on the thermoelectric properties of quantum

  19. Phonon impact on optical control schemes of quantum dots: Role of quantum dot geometry and symmetry

    Science.gov (United States)

    Lüker, S.; Kuhn, T.; Reiter, D. E.

    2017-12-01

    Phonons strongly influence the optical control of semiconductor quantum dots. When modeling the electron-phonon interaction in several theoretical approaches, the quantum dot geometry is approximated by a spherical structure, though typical self-assembled quantum dots are strongly lens-shaped. By explicitly comparing simulations of a spherical and a lens-shaped dot using a well-established correlation expansion approach, we show that, indeed, lens-shaped dots can be exactly mapped to a spherical geometry when studying the phonon influence on the electronic system. We also give a recipe to reproduce spectral densities from more involved dots by rather simple spherical models. On the other hand, breaking the spherical symmetry has a pronounced impact on the spatiotemporal properties of the phonon dynamics. As an example we show that for a lens-shaped quantum dot, the phonon emission is strongly concentrated along the direction of the smallest axis of the dot, which is important for the use of phonons for the communication between different dots.

  20. Quantum Phase Transitions in Quantum Dots

    OpenAIRE

    Rau, I. G.; Amasha, S.; Oreg, Y.; Goldhaber-Gordon, D.

    2013-01-01

    This review article describes theoretical and experimental advances in using quantum dots as a system for studying impurity quantum phase transitions and the non-Fermi liquid behavior at the quantum critical point.

  1. Double quantum dots defined in bilayer graphene

    Science.gov (United States)

    Żebrowski, D. P.; Peeters, F. M.; Szafran, B.

    2017-07-01

    Artificial molecular states of double quantum dots defined in bilayer graphene are studied with the atomistic tight-binding method and its low-energy continuum approximation. We indicate that the extended electron wave functions have opposite parities on sublattices of the layers and that the ground-state wave-function components change from bonding to antibonding with the interdot distance. In the weak-coupling limit, the one most relevant for quantum dots defined electrostatically, the signatures of the interdot coupling include, for the two-electron ground state, formation of states with symmetric or antisymmetric spatial wave functions split by the exchange energy. In the high-energy part of the spectrum the states with both electrons in the same dot are found with the splitting of energy levels corresponding to simultaneous tunneling of the electron pair from one dot to the other.

  2. 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...

  3. 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...

  4. Carbon Quantum Dots for Zebrafish Fluorescence Imaging

    National Research Council Canada - National Science Library

    Kang, Yan-Fei; Li, Yu-Hao; Fang, Yang-Wu; Xu, Yang; Wei, Xiao-Mi; Yin, Xue-Bo

    2015-01-01

    Carbon quantum dots (C-QDs) are becoming a desirable alternative to metal-based QDs and dye probes owing to their high biocompatibility, low toxicity, ease of preparation, and unique photophysical properties...

  5. Preparation and Application of Fluorescent Carbon Dots

    National Research Council Canada - National Science Library

    Zuo, Jun; Jiang, Tao; Zhao, Xiaojing; Xiong, Xiaohong; Xiao, Saijin; Zhu, Zhiqiang

    2015-01-01

      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...

  6. Nanomaterials: Earthworms lit with quantum dots

    Science.gov (United States)

    Tilley, Richard D.; Cheong, Soshan

    2013-01-01

    Yeast, bacteria and fungi have been used to synthesize a variety of nanocrystals. Now, the metal detoxification process in the gut of an earthworm is exploited to produce biocompatible cadmium telluride quantum dots.

  7. Micromagnetic Simulations of Submicron Cobalt Dots

    Energy Technology Data Exchange (ETDEWEB)

    Parker, G.J.; Cerjan, C.

    1999-08-30

    Numerical simulations of submicron Co extruded elliptical dots were performed to illustrate the relative importance of different physical parameters on the switching behavior in the easy direction. Shape, size, magnetic moment magnitude and crystalline anisotropy, both magnitude and distribution, were varied. The simulation includes calculation of the magnetostatic, exchange and crystalline anisotropy fields on a structured mesh using finite difference techniques. The smooth boundary of the dots are accurately represented by use of the Embedded Curve Boundary method.

  8. 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.

  9. Quantum dots and spin qubits in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Recher, Patrik; Trauzettel, Bjoern, E-mail: precher@physik.uni-wuerzburg.de, E-mail: trauzettel@physik.uni-wuerzburg.de [Institut fuer Theoretische Physik und Astrophysik, University of Wuerzburg, 97074 Wuerzburg (Germany)

    2010-07-30

    This is a review on graphene quantum dots and their use as a host for spin qubits. We discuss the advantages but also the challenges to use graphene quantum dots for spin qubits as compared to the more standard materials like GaAs. We start with an overview of this young and fascinating field and then discuss gate-tunable quantum dots in detail. We calculate the bound states for three different quantum dot architectures where a bulk gap allows for confinement via electrostatic fields: (i) graphene nanoribbons with armchair boundaries, (ii) a disc in single-layer graphene, and (iii) a disc in bilayer graphene. In order for graphene quantum dots to be useful in the context of spin qubits, one needs to find reliable ways to break the valley degeneracy. This is achieved here, either by a specific termination of graphene in (i) or in (ii) and (iii) by a magnetic field, without the need of a specific boundary. We further discuss how to manipulate spin in these quantum dots and explain the mechanism of spin decoherence and relaxation caused by spin-orbit interaction in combination with electron-phonon coupling, and by hyperfine interaction with the nuclear-spin system. (topical review)

  10. Semiconductor Quantum Dots with Photoresponsive Ligands.

    Science.gov (United States)

    Sansalone, Lorenzo; Tang, Sicheng; Zhang, Yang; Thapaliya, Ek Raj; Raymo, Françisco M; Garcia-Amorós, Jaume

    2016-10-01

    Photochromic or photocaged ligands can be anchored to the outer shell of semiconductor quantum dots in order to control the photophysical properties of these inorganic nanocrystals with optical stimulations. One of the two interconvertible states of the photoresponsive ligands can be designed to accept either an electron or energy from the excited quantum dots and quench their luminescence. Under these conditions, the reversible transformations of photochromic ligands or the irreversible cleavage of photocaged counterparts translates into the possibility to switch luminescence with external control. As an alternative to regulating the photophysics of a quantum dot via the photochemistry of its ligands, the photochemistry of the latter can be controlled by relying on the photophysics of the former. The transfer of excitation energy from a quantum dot to a photocaged ligand populates the excited state of the species adsorbed on the nanocrystal to induce a photochemical reaction. This mechanism, in conjunction with the large two-photon absorption cross section of quantum dots, can be exploited to release nitric oxide or to generate singlet oxygen under near-infrared irradiation. Thus, the combination of semiconductor quantum dots and photoresponsive ligands offers the opportunity to assemble nanostructured constructs with specific functions on the basis of electron or energy transfer processes. The photoswitchable luminescence and ability to photoinduce the release of reactive chemicals, associated with the resulting systems, can be particularly valuable in biomedical research and can, ultimately, lead to the realization of imaging probes for diagnostic applications as well as to therapeutic agents for the treatment of cancer.

  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. 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. BIEN-ÊTRE EN LYCÉE PROFESSIONNEL ET AVENIR ENVISAGÉ : Le cas des élèves préparant le bac professionnel

    OpenAIRE

    Lemistre, Philippe

    2017-01-01

    National audience; L'objectif de cet article est d'étudier le bien-être des lycéens professionnels, en lien avec les perspectives post-bac qu'ils envisagent. Après une discussion sur les approches disciplinaires du bien-être, les investigations ont été menées à partir d'une enquête réalisée en 2014 dans cinq lycées professionnels pour 963 lycéens de première et terminale (hors apprentissage). Quatre scores ont été constitués, chacun se rapportant à un registre spécifique : « conditions scolai...

  14. 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.

  15. Concepción del bien común en el pensamiento de Salvador Cisneros Betancourt: fundamento ético de un pensamiento político

    Directory of Open Access Journals (Sweden)

    Lic. Yudith Sotomayor-Gil

    2015-10-01

    Full Text Available Este trabajo se centra en el tratamiento teórico y desarrollo histórico de la categoría ética de bien común y su presencia, como fundamento, en el pensamiento político de Salvador Cisneros Betancourt, figura notoria y controversial de la historia de Cuba. Este tema, que se revela como continuidad de la tradición ética en que se sostiene el pensamiento cubano desde su momento fundacional, no ha recibido un tratamiento sistemático en la literatura filosófica cubana actual. El análisis de los documentos, en especial los que se inscriben entre 1902 y 1914, permite apreciar que, aunque no la aborde de forma explícita, la concepción del bien común permea el quehacer intelectual de Cisneros en esos años.

  16. Cristianos y mudéjares ante la conversión de 1502 : mercedes a moros, mercedes de bienes de moros

    Directory of Open Access Journals (Sweden)

    Pablo Ortega Rico

    2011-01-01

    Full Text Available Estudio del proceso de conversión de los mudéjares castellanos en 1502 atendiendo especialmente a las fórmulas de atracción desarrolladas por la Monarquía y los concejos a través de la entrega de mercedes a los nuevos conversos, y a las transformaciones en la titularidad de la propiedad de las mezquitas y «bienes comunes» asociadas al proceso de disolución de aljamas operado.This study examines the conversion process of Castilian Mudejars in 1502. We will specifically focus on the incentives developed by the Monarchy and town councils through grants to new converts as well as the changes in ownership of mosques and property ascribed to them (bienes comunes associated with the disintegration of the Mudejar communities.

  17. Bien-être au travail, une approche centrée sur la cohérence de rôle.

    OpenAIRE

    Robert, N.

    2007-01-01

    Dans un contexte où le monde du travail semble se durcir, il peut paraître paradoxal de voir émerger la notion de bien-être au travail. Elle est cependant de plus en plus utilisée, mais en analysant ce à quoi elle renvoie pour ceux qui s'y référent, on constate que les points de vue sont assez différents. Cette note scientifique et technique est une réflexion théorique dont l'objectif est double. Elle propose d'une part quelques clés permettant de clarifier ce que recouvre la notion de bien-ê...

  18. “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.

  19. 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.

  20. Micromagnetic calculations of Co dots: domain configuration, stability, and inter-dot coupling

    Science.gov (United States)

    Yu, Chengtao; Pearson, John; Li, Dongqi

    2002-03-01

    We have carried out micromagnetic simulations with a public code [1] to investigate the stability of single domain vs. vortex states in hexagonal Co dots of 10-900 nm in diameter and 1-40 nm in thickness, as well as the magnetostatic interactions among dots. The ground state of an isolated dot is determined to be single-domain for small dots, i.e., magneto-static coupling within a dot-pair introduces a uniaxial anisotropy with easy axis along the pair direction, which corresponds to 5 Oe at a pair distance of 640 nm, and increases to 270 Oe when two dots connect to each other. The results are compared to the experimental results of our self-assembled Co dots and dot chains [2]. * Work supported by DOE BES-MS under #W-31-109-ENG-38. 1. M.J. Donahue and D.G. Porter, http://math.nist.gov/oommf. 2. Chengtao Yu, Dongqi Li, J. Pearson, and S. Bader, Appl. Phys. Lett. 78, 1228 (2001); ibid. 79 (in press).

  1. Quatre éléments clés pour favoriser la santé et le bien-être pour tous ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    14 sept. 2017 ... Les 17 objectifs de développement durable (ODD) sont ambitieux et mettent le bien-être de la population mondiale à l'avant-plan. Ils ont été adoptés par 194 pays au mois de septembre 2015. Mettant plus particulièrement l'accent sur la santé, l'ODD no 3 aura une influence sur l'atteinte des 16 autres ODD ...

  2. Los bienes humanos básicos y la fundamentación del derecho. Un estudio de la propuesta de john finnis Basic Human Goods and the

    Directory of Open Access Journals (Sweden)

    Marina Dandois

    2014-01-01

    Full Text Available Este trabajo busca dilucidar en qué medida la explicación sobre los bienes humanos básicos ofrecida por el iusfilósofo australiano John Finnis puede ser de utilidad para dar cuenta del fenómeno jurídico actual. Ello así, dada la incorporación en la mayoría de los textos constitucionales ocidentales de derechos fundamentales —en muchos casos recogidos como principios— y de sistemas de control de constitucionalidad, que supone reconocer, entre otras cosas, que los sistemas jurídicos no solo están formados por reglas, sino también por principios capaces de dirigir la acción como Derecho directamente aplicable y que la validez de las reglas del sistema depende no sólo de su corrección formal, sino también de su compatibilidad con los derechos fundamentales recogidos constitucionalmente. Para ello, en primer lugar se desarrollará la noción de bienes humanos básicos y los caracteres que aquellos comparten – autoevidentes, pre-morales y fundamentales. Luego se tendrán en cuenta los diversos desafíos que pueden planteárseles a los bienes humanos básicos en lo que respecta a ser todos ellos igualmente autoevidentes, pre-morales y fundamentales, y se sugerirán posibles respuestas a dichas objeciones. De este estudio se arribará a una conclusión sobre la idoneidad de los bienes humanos básicos para constituir puntos de partida irreductibles, inderivables y directivos, que permitan formular el conjunto de estándares morales generales de los que se nutren los principios constitucionales.

  3. Computational intelligence applied to the growth of quantum dots

    Science.gov (United States)

    Singulani, Anderson P.; Vilela Neto, Omar P.; Aurélio Pacheco, Marco C.; Vellasco, Marley B. R.; Pires, Maurício P.; Souza, Patrícia L.

    2008-11-01

    We apply two computational intelligence techniques, namely, artificial neural network and genetic algorithm to the growth of self-assembled quantum dots. The method relies on an existing database of growth parameters with a resulting quantum dot characteristic to be able to later obtain the growth parameters needed to reach a specific value for such a quantum dot characteristic. The computational techniques were used to associate the growth input parameters with the mean height of the deposited quantum dots. Trends of the quantum dot mean height behavior as a function of growth parameters were correctly predicted and the growth parameters required to minimize the quantum dot mean height were provided.

  4. 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.

  5. 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.

  6. Dot gain compensation in the blue noise mask

    Science.gov (United States)

    Yao, Meng; Parker, Kevin J.

    1995-04-01

    Frequency modulated (FM) halftoning or 'stochastic screening,' has attracted a great deal of attention in the printing industry in recent years. It has several advantages over conventional halftoning. But one serious problem that arises in FM halftoning is dot gain. One approach to stochastic screening uses a specially constructed halftone screen, the blue noise mask (BNM), to produce an unstructured and visually appealing pattern of halftone dots at any gray level. In this paper, we will present methods to correct dot gain with the BNM. Dot gain is related to the area-to-perimeter ration of printed spots. We can exploit this feature in different ways. At a medium level, a B>NM pattern will have 'connected' as well as 'isolated' dots. Normally, as we build down BNM patterns to lower levels, a specific number of white dots will be replace by black dots. Since connected white dots are more likely to be picked than isolated white dots, this will results in substantial dot gain because of the increasing number of isolated white dots. We show that it is possible to constrain the process of constructing a BNM such that isolated dots are preferentially removes, thus significantly reducing dot gain in a BNM.

  7. Corrélats du bien-être chez les Canadiens présentant des troubles de l’humeur ou d'anxiété

    Directory of Open Access Journals (Sweden)

    H. Orpana

    2016-01-01

    Full Text Available Introduction : Notre objectif visait à étudier les variables liées au bien-être, mesurées par une autoévaluation de la santé mentale (AESM très positive et une satisfaction élevée à l’égard de la vie (SV chez des adultes canadiens (âgés de 18 ans et plus présentant un trouble de l’humeur ou d'anxiété. Méthodologie : Nous avons utilisé des données nationales représentatives tirées de l’Enquête sur les personnes ayant une maladie chronique au Canada – Composante des troubles de l’humeur et d’anxiété (EPMCC-TAH de 2014 afin de décrire l’association entre bien-être et comportements d’autogestion (activité physique, sommeil et méditation ainsi que stress, adaptation et soutien social perçus. Nous avons eu recours à une régression logistique multivariée pour modéliser la relation entre ces facteurs et les mesures du bien-être. Résultats : Environ une personne sur trois atteinte d’un trouble de l’humeur ou d’anxiété a fait état d'une AESM positive. Les modèles de régression logistique ont révélé que plusieurs caractéristiques, comme un âge plus avancé, une autoévaluation de la santé générale positive, des limitations fonctionnelles moins nombreuses ainsi que la perception d’un moindre stress à l’égard de la vie, de meilleures capacités d’adaptation et d’un plus grand soutien social, étaient associées à des niveaux de bien-être plus élevés. Les comportements d’autogestion (entamer une activité physique, méditer, adopter de saines habitudes de sommeil et atteindre un certain nombre d’heures de sommeil chaque nuit n’étaient pas significativement associés à des mesures du bien-être dans notre modèle multivarié. Conclusion : Les adultes canadiens souffrant de troubles de l’humeur ou d'anxiété qui ont déclaré percevoir un niveau de stress plus faible, un plus grand soutien social et une meilleure capacité d’adaptation étaient plus susceptibles de

  8. AlInAs quantum dots

    Science.gov (United States)

    Gaisler, A. V.; Derebezov, I. A.; Gaisler, V. A.; Dmitriev, D. V.; Toropov, A. I.; Kozhukhov, A. S.; Shcheglov, D. V.; Latyshev, A. V.; Aseev, A. L.

    2017-01-01

    A system of quantum dots on the basis of AlxIn1-xAs/AlyGa1-y As solid solutions has been studied. The usage of broadband AlxIn1-x solid solutions as the basis of quantum dots makes it possible to expand considerably the spectral emission range into the short-wave region, including the wavelength region near 770 nm being of interest for the design of aerospace systems of quantum cryptography. The optical characteristics of single AlxIn1-xAs quantum dots grown according to the Stranski-Krastanov mechanism are studied by the cryogenic microphotoluminescence method. The fine structure of exciton states of quantum dots is studied in the wavelength region near 770 nm. It is shown that the splitting of exciton states is comparable with the natural width of exciton lines, which is of great interest for the design of emitters of pairs of entangled photons on the basis of AlxAs1-x quantum dots.

  9. Electrostatically confined trilayer graphene quantum dots

    Science.gov (United States)

    Mirzakhani, M.; Zarenia, M.; Vasilopoulos, P.; Peeters, F. M.

    2017-04-01

    Electrically gating of trilayer graphene (TLG) opens a band gap offering the possibility to electrically engineer TLG quantum dots. We study the energy levels of such quantum dots and investigate their dependence on a perpendicular magnetic field B and different types of stacking of the graphene layers. The dots are modeled as circular and confined by a truncated parabolic potential which can be realized by nanostructured gates or position-dependent doping. The energy spectra exhibit the intervalley symmetry EKe(m ) =-EK'h(m ) for the electron (e ) and hole (h ) states, where m is the angular momentum quantum number and K and K ' label the two valleys. The electron and hole spectra for B =0 are twofold degenerate due to the intervalley symmetry EK(m ) =EK'[-(m +1 ) ] . For both ABC [α =1.5 (1.2) for large (small) R ] and ABA (α =1 ) stackings, the lowest-energy levels show approximately a R-α dependence on the dot radius R in contrast with the 1 /R3 one for ABC-stacked dots with infinite-mass boundary. As functions of the field B , the oscillator strengths for dipole-allowed transitions differ drastically for the two types of stackings.

  10. Thermoelectric properties of hexagonal graphene quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yonghong, E-mail: yhyan@fudan.edu.cn [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Liang, Qi-Feng [Department of Physics, Shaoxing University, Shaoxing 312000 (China); Zhao, Hui [Department of Physics, Tongji University, Shanghai 200092 (China); Wu, Chang-Qin [Department of Physics, Fudan University, Shanghai 200433 (China)

    2012-02-27

    By using the atomistic nonequilibrium Green's function method, we investigate the thermoelectric properties of graphene nanoribbons in the presence of two constrictions (or hexagonal graphene quantum dots). With decreasing widths of the constrictions, the thermal conductance of the nanoribbon can be reduced largely while S{sup 2}G{sub e} (S is the Seebeck coefficient and G{sub e} is the electronic conductance) remains still high as compared with the results of the pristine nanoribbon. Thus, the thermoelectric figure of merit ZT can be enhanced largely. In fact, in the presence of narrowest constrictions the ZT values of the zigzag quantum dots can exceed one at room temperature, while the ZT values of the armchair quantum dots may be close to one, depending on the size of the dot. -- Highlights: ► We study thermoelectric properties of hexagonal graphene quantum dots. ► By point contacts to two leads, the thermal conductance can be reduced greatly while keeping the power factor still high. ► Thermoelectric figure of merit (ZT) can exceed unity.

  11. Analysis of MoDOT communication and outreach effectiveness

    Science.gov (United States)

    2008-07-01

    Personal interviews were held with MoDOT personnel to assess MoDOTs current communication practices and existing customer segmentation practices. Focus groups were then held to help gauge the effectiveness of existing communication practices and t...

  12. 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.

  13. TxDOT administration research : tasks completed in FY2009.

    Science.gov (United States)

    2010-01-01

    Texas Department of Transportation (TxDOT) Project 0-6581-TI, TxDOT Administration : Research, encompasses multiple tasks that explore and support administrative aspects of : transportation research. : The project term began in October 2008 and has b...

  14. Surface treatment of nanocrystal quantum dots after film deposition

    Science.gov (United States)

    Sykora, Milan; Koposov, Alexey; Fuke, Nobuhiro

    2015-02-03

    Provided are methods of surface treatment of nanocrystal quantum dots after film deposition so as to exchange the native ligands of the quantum dots for exchange ligands that result in improvement in charge extraction from the nanocrystals.

  15. Few-quantum-dot lasing in photonic crystal nanocavities

    DEFF Research Database (Denmark)

    Liu, Jin; Ates, Serkan; Stobbe, Søren

    2012-01-01

    A very smooth lasing transition in photonic crystal nanocavities with embedded quantum dots is observed and compared to the theory. Decay rate measurements reveal that only a few quantum dots are feeding the cavity....

  16. 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.

  17. 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....

  18. Modulation Response of Semiconductor Quantum Dot Nanocavity Lasers

    DEFF Research Database (Denmark)

    Lorke, Michael; Nielsen, Torben Roland; Mørk, Jesper

    2011-01-01

    The modulation response of quantum-dot based nanocavity devices is investigated using a semiconductor theory. We show that high modulation bandwidth is achieved even in the presence of inhomogeneous broadening of the quantum dot ensemble.......The modulation response of quantum-dot based nanocavity devices is investigated using a semiconductor theory. We show that high modulation bandwidth is achieved even in the presence of inhomogeneous broadening of the quantum dot ensemble....

  19. Carbon quantum dots and a method of making the same

    Science.gov (United States)

    Zidan, Ragaiy; Teprovich, Joseph A.; Washington, Aaron L.

    2017-08-22

    The present invention is directed to a method of preparing a carbon quantum dot. The carbon quantum dot can be prepared from a carbon precursor, such as a fullerene, and a complex metal hydride. The present invention also discloses a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride and a polymer containing a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride.

  20. A roadmap towards habitable exoplanets by the Blue Dots Initiative

    Science.gov (United States)

    Coudé du Foresto, V.

    2011-11-01

    This paper is an abridged version of the report produced by the Blue Dots initiative, whose activities include the elaboration of a roadmap towards the spectroscopic characterization of habitable exoplanets. The full version of the Blue Dots report can be downloaded at http://www.blue-dots.net/spip.php?article105. While the roadmap will need to be updated regularly, it is expected that the methodology developed within Blue Dots will provide a durable framework for the elaboration of future revisions.

  1. Fluorescent carbon nanomaterials: "quantum dots" or nanoclusters?

    Science.gov (United States)

    Dekaliuk, Mariia O; Viagin, Oleg; Malyukin, Yuriy V; Demchenko, Alexander P

    2014-08-14

    Despite many efforts, the mechanisms of light absorption and emission of small fluorescent carbon nanoparticles (C-dots) are still unresolved and are a subject of active discussion. In this work we address the question as to whether the fluorescence is a collective property of these nanoparticles or they are composed of assembled individual emitters. Selecting three types of C-dots with "violet", "blue" and "green" emissions and performing a detailed study of fluorescence intensity, lifetime and time-resolved anisotropy as a function of excitation and emission wavelengths together with the effect of viscogen and dynamic fluorescence quencher, we demonstrate that the C-dots represent assemblies of surface-exposed fluorophores. They behave as individual emitters, display electronic anisotropy, do not exchange their excited-state energies via homo-FRET and possibly display sub-nanosecond intra-particle mobility.

  2. Magnon cotunneling through a quantum dot

    Science.gov (United States)

    Karwacki, Łukasz

    2017-11-01

    I consider a single-level quantum dot coupled to two reservoirs of spin waves (magnons). Such systems have been studied recently from the point of view of possible coupling between electronic and magnonic spin currents. However, usually weakly coupled systems were investigated. When coupling between the dot and reservoirs is not weak, then higher order processes play a role and have to be included. Here I consider cotunneling of magnons through a spin-occupied quantum dot, which can be understood as a magnon (spin) leakage current in analogy to leakage currents in charge-based electronics. Particular emphasis has been put on investigating the effect of magnetic field and temperature difference between the magnonic reservoirs.

  3. 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.

  4. 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.

  5. Electron-hole confinement symmetry in silicon quantum dots

    NARCIS (Netherlands)

    Müller, F.; Mueller, Filipp; Konstantaras, Georgios; Spruijtenburg, P.C.; van der Wiel, Wilfred Gerard; Zwanenburg, Floris Arnoud

    2015-01-01

    We report electrical transport measurements on a gate-defined ambipolar quantum dot in intrinsic silicon. The ambipolarity allows its operation as either an electron or a hole quantum dot of which we change the dot occupancy by 20 charge carriers in each regime. Electron−hole confinement symmetry is

  6. 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 detail...... methods for use with commercially available quantum dots and discuss common difficulties....

  7. 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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Magnetoconductivity of quantum dots with Rashba interaction

    Science.gov (United States)

    Lipparini, E.; Barranco, M.; Malet, F.; Pi, M.

    2009-03-01

    We address the magnetoconductivity of a quantum dot with Rashba spin-orbit interaction within linear-response theory. As a consequence of the generalized Kohn’s theorem, the magnetoconductivity of the dot is zero when the spin-orbit coupling is neglected. The inclusion of the spin-orbit interaction violates the mentioned theorem and gives rise to a nonzero magnetoconductivity. We derive a simple expression for this quantity valid up to the second order in the Rashba parameter. In the limit of vanishing lateral confinement, i.e., for a quantum well, a similar calculation yields the quantum Hall-effect result.

  9. Covalent functionalized black phosphorus quantum dots

    Science.gov (United States)

    Scotognella, Francesco; Kriegel, Ilka; Sassolini, Simone

    2018-01-01

    Black phosphorus (BP) nanostructures enable a new strategy to tune the electronic and optical properties of this atomically thin material. In this paper we show, via density functional theory calculations, the possibility to modify the optical properties of BP quantum dots via covalent functionalization. The quantum dot selected in this study has chemical formula P24H12 and has been covalent functionalized with one or more benzene rings or anthracene. The effect of functionalization is highlighted in the absorption spectra, where a red shift of the absorption is noticeable. The shift can be ascribed to an electron delocalization in the black phosphorus/organic molecule nanostructure.

  10. Dot probe performance in two specific phobias.

    Science.gov (United States)

    Wenzel, A; Holt, C S

    1999-11-01

    The present study applied MacLeod, Mathews & Tata's (1986) dot probe attentional deployment methodology to individuals with specific phobias. Attentional deployment towards spider-related, blood-related, positive, negative, and neutral words was examined. Individuals with either spider phobia (N = 13) or blood/injury phobia (N = 14) and non-anxious controls (N = 14) completed the dot probe attentional deployment task. Individuals with specific phobias did not demonstrate an attentional bias towards phobia-related stimuli relevant to their particular fears. Semantic-based information processing paradigms may not be sufficiently potent to demonstrate biased performance towards threatening stimuli in individuals with mild specific phobias who are otherwise healthy.

  11. 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

  12. Mitigation of quantum dot cytotoxicity by microencapsulation.

    Science.gov (United States)

    Romoser, Amelia; Ritter, Dustin; Majitha, Ravish; Meissner, Kenith E; McShane, Michael; Sayes, Christie M

    2011-01-01

    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.

  13. 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.

  14. Potential clinical applications of quantum dots

    Science.gov (United States)

    Medintz, Igor L; Mattoussi, Hedi; Clapp, Aaron R

    2008-01-01

    The use of luminescent colloidal quantum dots in biological investigations has increased dramatically over the past several years due to their unique size-dependent optical properties and recent advances in biofunctionalization. In this review, we describe the methods for generating high-quality nanocrystals and report on current and potential uses of these versatile materials. Numerous examples are provided in several key areas including cell labeling, biosensing, in vivo imaging, bimodal magnetic-luminescent imaging, and diagnostics. We also explore toxicity issues surrounding these materials and speculate about the future uses of quantum dots in a clinical setting. PMID:18686776

  15. Spin qubits in graphene quantum dots

    OpenAIRE

    Trauzettel, Björn; Bulaev, Denis V.; Loss, Daniel; Burkard, Guido

    2006-01-01

    We propose how to form spin qubits in graphene. A crucial requirement to achieve this goal is to find quantum dot states where the usual valley degeneracy in bulk graphene is lifted. We show that this problem can be avoided in quantum dots based on ribbons of graphene with semiconducting armchair boundaries. For such a setup, we find the energies and the exact wave functions of bound states, which are required for localized qubits. Additionally, we show that spin qubits in graphene can not on...

  16. 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.

  17. Improved dot size uniformity and luminescense of InAs quantum dots on InP substrate

    Science.gov (United States)

    Qiu, Y.; Uhl, D.

    2002-01-01

    InAs self-organized quantum dots have been grown in InGaAs quantum well on InP substrates by metalorganic vapor phase epitaxy. Atomic Force Microscopy confirmed of quantum dot formation with dot density of 3X10(sup 10) cm(sup -2). Improved dot size uniformity and strong room temperature photoluminescence up to 2 micron were observed after modifying the InGaAs well.

  18. Solution-Processable ZnO/Carbon Quantum Dots Electron Extraction Layer for Highly Efficient Polymer Solar Cells.

    Science.gov (United States)

    Zhang, Ruqin; Zhao, Min; Wang, Zhongqiang; Wang, Zongtao; Zhao, Bo; Miao, Yanqin; Zhou, Yingjuan; Wang, Hua; Hao, Yuying; Chen, Guo; Zhu, Furong

    2018-01-26

    In this work, we report the effort to develop high-efficiency inverted polymer solar cells (PSCs) by applying a solution-processable bilayer ZnO/carbon quantum dots (C-QDs) electron extraction layer (EEL). It is shown that the use of the bilayer EEL helps to suppress the exciton quenching by passivating the ZnO surface defects in the EEL, leading to an enhanced exciton dissociation, reduced charge recombination and more efficient charge extraction probability, and thereby achieving high power conversion efficiency (PCE). The inverted PSCs, based on the blend of poly{4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} and [6,6]-phenyl C71-butyric acid methyl ester, possess a significant improvement in PCE of ∼9.64%, which is >27% higher than that of a control cell (∼7.59%). The use of a bilayer ZnO/C-QD EEL offers a promising approach for attaining high-efficiency inverted PSCs.

  19. 49 CFR 40.13 - How do DOT drug and alcohol tests relate to non-DOT tests?

    Science.gov (United States)

    2010-10-01

    ... respects. (b) DOT tests must take priority and must be conducted and completed before a non-DOT test is... a blood or urine specimen collected by the employee's physician or a DNA test result purporting to... 49 Transportation 1 2010-10-01 2010-10-01 false How do DOT drug and alcohol tests relate to non...

  20. 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...

  1. AVANCES Y PERSPECTIVAS DEL DERECHO PARA LA RESTITUCIÓN DE BIENES CULTURALES A SUS PAÍSES DE ORIGEN EL CASO DEL PATRIMONIO CULTURAL

    Directory of Open Access Journals (Sweden)

    Antonio José Rengifo Lozano

    2008-01-01

    Partenón, promovido por Grecia y del patrimonio cultural quimbaya en Colombia, la presente ponencia 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 legitimo derecho de los pueblos a conocer, apreciar, disfrutar y difundir el patrimonio expresión de su identidad, de su cultura y de su historia.

  2. Propuesta de una estrategia de negocios para la comercialización en línea de bienes y servicios culturales

    OpenAIRE

    Angulo Ruiz, Manuel; Gil Tommee, Rebeca

    2011-01-01

    Tesis de maestría -- Universidad de Costa Rica. Posgrado en Administración y Dirección de Empresas. Maestría Profesional en Administración y Dirección de Empresas con énfasis en Finanzas, 2011 El objetivo general del trabajo es elaborar una estrategia de negocios para la creación de una tienda en línea que sea financieramente sostenible y se convierta en la empresa líder en comercializar bienes y servicios culturales procedentes de museos y entidades culturales en América Latina, en un per...

  3. Ingresos y bienes en la vejez, un acercamiento a la configuración de la seguridad económica de los adultos mayores mexiquenses

    Directory of Open Access Journals (Sweden)

    Mariana MADRIGAL-MARTÍNEZ

    2010-01-01

    Full Text Available El propósito del artículo es establecer la conformación de la seguridad económica de la población adulta mayor mexiquense con base en las fuentes de ingreso y bienes a las que tiene acceso. Los resultados de la encuesta ESEDEM 2008 comprueban la hipótesis de que la seguridad económica está fuertemente relacionada con el perfil sociodemográfico del adulto mayor y muestra serias desventajas para los grupos que presentan características asociadas con mayores niveles de exclusión.

  4. Medición simplificada del nivel socioeconómico en encuestas breves: propuesta a partir de acceso a bienes y servicios

    OpenAIRE

    Juan Pablo Gutiérrez; Rodrigo Díaz-Acosta; Andrey Ryo Shiba-Matsumoto

    2015-01-01

    Objetivo. Desarrollar un indicador socioeconómico para encuestas breves que permita una clasificación en relación con un criterio poblacional y que resulte parsimonioso. Material  métodos. Se generó un indicador socioeconómico a partir de variables dicotómicas de bienes y servicios. Se obtuvo la correlación de los resultados obtenidos de la Encuesta Nacional de Ingresos y Gastos en los Hogares ENIGH con los de una encuesta breve y se les comparó con los de un indicador construido a partir de ...

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

    OpenAIRE

    Mónica B. Rotman

    2016-01-01

    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 prod...

  6. Juan XXIII y la encíclica Pacem in terris: La relación entre bien común y subsidiaridad

    OpenAIRE

    Guitián, G. (Gregorio)

    2014-01-01

    El autor conmemora la figura de Juan XXIII presentando una reflexión sobre la unidad entre bien común y subsidiaridad en Pacem in terris, su última encíclica social. Pacem in terris aparece como un buen ejemplo de la unidad e inseparabilidad de los principios de la Doctrina Social de la Iglesia. El artículo se ocupa también de las referencias al orden divino y señala la presencia de un trasfondo tomista en la encíclica. Además, el autor hace algunos comentarios sobre el carácter innovador de ...

  7. 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

  8. Análisis, diseño y desarrollo de un portal administrable para empresas dedicadas a la actividad de bienes raíces

    OpenAIRE

    Manzo Zamora, Cecilia; Rugel Mora, Priscila; Vargas Jaramillo, Katty; Freire Cobo, Lenin Eduardo

    2009-01-01

    Viendo las necesidades actuales del mercado inmobiliario hemos decidido desarrollar un Portal administrable para llevar a cabo el negocio de bienes raíces a través del Internet, el cual tendrá el nombre de InmoSoft y será vendido a las principales inmobiliarias de la provincia. El Portal estará enfocado a diferentes fases del negocio, tales como: Clientes de la Inmobiliaria (registro de datos de los futuros clientes, consulta de los inmuebles), Agentes Vendedores (registro de cada una de ...

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

    Directory of Open Access Journals (Sweden)

    Alessandra eCelletti

    2016-03-01

    Full Text Available 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 thenearby future. A relevant role in space debris is played by lunisolarsecular resonances, which might contribute to an increase of the orbitalelements, typically of the eccentricity. We concentrate our attention onthe lunisolar secular resonance described by the relation$2dot{omega}+dot{Omega}=0$, where $omega$ and $Omega$ denotethe 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 $2dot{omega}+dot{Omega}=0$, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  10. Generation of singlet oxygen and other radical species by quantum dot and carbon dot nanosensitizers

    Science.gov (United States)

    Generalov, Roman; Christensen, Ingeborg L.; Chen, Wei; Sun, Ya-Ping; Kristensen, Solveig; Juzenas, Petras

    2009-06-01

    Medicinal applications of luminescent semiconductor quantum dots are of growing interest. In spite of the fact that their fabrication and imaging applications have been extensively investigated for the last decade, very little is documented on photodynamic action of quantum dots. In this study we demonstrate generation of singlet oxygen and other radical species upon exposure of quantum dots to blue light and therapeutic red light. Extent of radical production can be readily modified by antioxidants. Lay and scientific communities are two sites concerning potential hazards and enthusiastic applications of nanotechnology. Synthesis of quantum dots composed of less toxic materials is of great interest. A new candidate is a ubiquitous element carbon, which on nanoscale exhibits strong photoluminescence.

  11. Lateral excitonic switching in vertically stacked quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Jarzynka, Jarosław R.; McDonald, Peter G.; Galbraith, Ian [Institute of Photonics and Quantum Sciences, SUPA, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Shumway, John [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

    2016-06-14

    We show that the application of a vertical electric field to the Coulomb interacting system in stacked quantum dots leads to a 90° in-plane switching of charge probability distribution in contrast to a single dot, where no such switching exists. Results are obtained using path integral quantum Monte Carlo with realistic dot geometry, alloy composition, and piezo-electric potential profiles. The origin of the switching lies in the strain interactions between the stacked dots hence the need for more than one layer of dots. The lateral polarization and electric field dependence of the radiative lifetimes of the excitonic switch are also discussed.

  12. 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. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. 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

  14. Mecanismos de exclusión de los pueblos originarios en los discursos y representaciones del Buen Vivir ecuatoriano y el Vivir Bien boliviano: el tutelaje y la desapropiación simbólica

    National Research Council Canada - National Science Library

    Pérez-Gañán, R

    2017-01-01

    This article have tried to take a close look at the (re)construction of identity among the indigenous populations with regards to State discourses and practices in the Ecuadorian Buen Vivir and the Bolivian Vivir Bien...

  15. 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.

  16. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    Energy Technology Data Exchange (ETDEWEB)

    Barettin, Daniele, E-mail: Daniele.Barettin@uniroma2.it; Auf der Maur, Matthias [Department of Electronic Engineering, University of Rome “Tor Vergata,” Via del Politecnico 1, 00133, Rome (Italy); De Angelis, Roberta; Prosposito, Paolo; Casalboni, Mauro [Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1 00133 Rome, Italy and INSTM, Unitá di ricerca dell' Universitá di Roma “Tor Vergata,” Via della Ricerca Scientifica 1, 00133, Rome (Italy); Pecchia, Alessandro [CNR-ISMN, via Salaria Km. 29.300, 00017 Monterotondo, Rome (Italy)

    2015-03-07

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In{sub 0.48}Ga{sub 0.52 }P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k{sup →}·p{sup →} bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots.

  17. Annealing-induced change in quantum dot chain formation mechanism

    Directory of Open Access Journals (Sweden)

    Tyler D. Park

    2014-12-01

    Full Text Available Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  18. Annealing-induced change in quantum dot chain formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Park, Tyler D.; Colton, John S.; Farrer, Jeffrey K. [Department of Physics and Astronomy, Brigham Young University, Provo UT 84602 (United States); Yang, Haeyeon [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Kim, Dong Jun [IPG Photonics Corporation, Oxford, MA 01540 (United States)

    2014-12-15

    Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  19. Spin-wave excitations in quantum dots

    Science.gov (United States)

    Lipparini, Enrico; Serra, Llorenç

    1998-03-01

    The transverse response function for a quantum dot in a uniform magnetic field B is calculated using current-density-functional theory. The poles corresponding to the ΔLz=+/-1 and ΔSz=+/-1 spin waves are investigated as a function of B.

  20. Orbital current mode in elliptical quantum dots

    Science.gov (United States)

    Serra, Llorenç; Puente, Antonio; Lipparini, Enrico

    1999-11-01

    An orbital current mode peculiar to deformed quantum dots is theoretically investigated; first by using a simple model that makes it possible to analytically interpret its main characteristics, and second, by numerically solving the microscopic equations of time evolution after an initial perturbation within the time-dependent local-spin-density approximation. Results for different deformations and sizes are shown.

  1. Competing interactions in semiconductor quantum dots

    NARCIS (Netherlands)

    van den Berg, R.; Brandino, G.P.; El Araby, O.; Konik, R.M.; Gritsev, V.; Caux, J.S.

    2014-01-01

    We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free-induction decay and spin-echo simulations

  2. 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...

  3. 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.

  4. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    Semiconductor quantum dots are often described as "artificial atoms": They are small nanometre-sized structures in which electrons only are allowed to exist at certain discrete levels due to size quantization, thus allowing the engineering of fundamental properties such as the coupling to light. ...

  5. Assembling quantum dots via critical Casimir forces

    NARCIS (Netherlands)

    Marino, E.; Kodger, T.E.; Hove, J.B. ten; Velders, A.H.; Schall, P.

    2016-01-01

    Programmed assembly of colloidal inorganic nanocrystal superstructures is crucial for the realization of future artificial solids as well as present optoelectronic applications. Here, we present a new way to assemble quantum dots reversibly using binary solvents. By tuning the temperature and

  6. Doppler broadening effects in plasmonic quantum dots

    Science.gov (United States)

    Alves, R. A.; Silva, Nuno A.; Costa, J. C.; Gomes, M.; Guerreiro, A.

    2017-08-01

    In this paper we analyse the effects of the Doppler shift on the optical response of a nanoplasmonic system. Through the development of a simplified model based on the Hydrodynamic Drude model we analyse the response of a quantum dot embed in a moving fluid, predicting the Doppler broadening and the shift of the spectral line.

  7. 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...

  8. Quantum-dot infrared photodetectors: a review

    Science.gov (United States)

    Stiff-Roberts, Adrienne D.

    2009-04-01

    Quantum-dot infrared photodetectors (QDIPs) are positioned to become an important technology in the field of infrared (IR) detection, particularly for high-temperature, low-cost, high-yield detector arrays required for military applications. High-operating temperature (>=150 K) photodetectors reduce the cost of IR imaging systems by enabling cryogenic dewars and Stirling cooling systems to be replaced by thermo-electric coolers. QDIPs are well-suited for detecting mid-IR light at elevated temperatures, an application that could prove to be the next commercial market for quantum dots. While quantum dot epitaxial growth and intraband absorption of IR radiation are well established, quantum dot non-uniformity remains as a significant challenge. Nonetheless, state-of-the-art mid-IR detection at 150 K has been demonstrated using 70-layer InAs/GaAs QDIPs, and QDIP focal plane arrays are approaching performance comparable to HgCdTe at 77 K. By addressing critical challenges inherent to epitaxial QD material systems (e.g., controlling dopant incorporation), exploring alternative QD systems (e.g., colloidal QDs), and using bandgap engineering to reduce dark current and enhance multi-spectral detection (e.g. resonant tunneling QDIPs), the performance and applicability of QDIPs will continue to improve.

  9. 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...

  10. Enabling biomedical research with designer quantum dots

    NARCIS (Netherlands)

    Tomczak, N.; Janczewski, D.; Dorokhin, D.V.; Han, M-Y; Vancso, Gyula 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.

  11. Electron Spins in Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Hanson, R.

    2005-01-01

    This thesis describes a series of experiments aimed at understanding and controlling the behavior of the spin degree of freedom of single electrons, confined in semiconductor quantum dots. This research work is motivated by the prospects of using the electron spin as a quantum bit (qubit), the basic

  12. 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

  13. Ostwald's ripening of nanostructures with quantum dots

    CERN Document Server

    Vengrenovich, R D; Yarema, S V

    2001-01-01

    The scenario of quantum dots shaping during ripening three-dimensional islands obtained by heteroepitaxy in a Stranski-Krastanow mode, is offered. It is shown that throughout the growth of dislocations with their subsequent separation from the island bottom, the size distribution function becomes narrower with noticeable diminishing the dispersion. The possible reasons for signal attenuation of Ostwald's ripening islands are analyzed

  14. Competitive performance of carbon "quantum" dots in optical bioimaging.

    Science.gov (United States)

    Cao, Li; Yang, Sheng-Tao; Wang, Xin; Luo, Pengju G; Liu, Jia-Hui; Sahu, Sushant; Liu, Yamin; Sun, Ya-Ping

    2012-01-01

    Carbon-based "quantum" dots or carbon dots are surface-functionalized small carbon nanoparticles. For bright fluorescence emissions, the carbon nanoparticles may be surface-doped with an inorganic salt and then the same organic functionalization. In this study, carbon dots without and with the ZnS doping were prepared, followed by gel-column fractionation to harvest dots of 40% and 60% in fluorescence quantum yields, respectively. These highly fluorescent carbon dots were evaluated for optical imaging in mice, from which bright fluorescence images were obtained. Of particular interest was the observed competitive performance of the carbon dots in vivo to that of the well-established CdSe/ZnS QDs. The results suggest that carbon dots may be further developed into a new class of high-performance yet nontoxic contrast agents for optical bioimaging.

  15. Optical properties of quantum-dot-doped liquid scintillators.

    Science.gov (United States)

    Aberle, C; Li, J J; Weiss, S; Winslow, L

    2013-10-14

    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.

  16. Three-dimensional Si/Ge quantum dot crystals.

    Science.gov (United States)

    Grützmacher, Detlev; Fromherz, Thomas; Dais, Christian; Stangl, Julian; Müller, Elisabeth; Ekinci, Yasin; Solak, Harun H; Sigg, Hans; Lechner, Rainer T; Wintersberger, Eugen; Birner, Stefan; Holý, Vaclav; Bauer, Günther

    2007-10-01

    Modern nanotechnology offers routes to create new artificial materials, widening the functionality of devices in physics, chemistry, and biology. Templated self-organization has been recognized as a possible route to achieve exact positioning of quantum dots to create quantum dot arrays, molecules, and crystals. Here we employ extreme ultraviolet interference lithography (EUV-IL) at a wavelength of lambda = 13.5 nm for fast, large-area exposure of templates with perfect periodicity. Si(001) substrates have been patterned with two-dimensional hole arrays using EUV-IL and reactive ion etching. On these substrates, three-dimensionally ordered SiGe quantum dot crystals with the so far smallest quantum dot sizes and periods both in lateral and vertical directions have been grown by molecular beam epitaxy. X-ray diffractometry from a sample volume corresponding to about 3.6 x 10(7) dots and atomic force microscopy (AFM) reveal an up to now unmatched structural perfection of the quantum dot crystal and a narrow quantum dot size distribution. Intense interband photoluminescence has been observed up to room temperature, indicating a low defect density in the three-dimensional (3D) SiGe quantum dot crystals. Using the Ge concentration and dot shapes determined by X-ray and AFM measurements as input parameters for 3D band structure calculations, an excellent quantitative agreement between measured and calculated PL energies is obtained. The calculations show that the band structure of the 3D ordered quantum dot crystal is significantly modified by the artificial periodicity. A calculation of the variation of the eigenenergies based on the statistical variation in the dot dimensions as determined experimentally (+/-10% in linear dimensions) shows that the calculated electronic coupling between neighboring dots is not destroyed due to the quantum dot size variations. Thus, not only from a structural point of view but also with respect to the band structure, the 3D ordered

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Edwin Cruz Rodríguez

    2014-09-01

    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.******This article examines the concept of live well-good living, by analyzing its contributions and limitations. This worldview has a normative horizon more ambitious than the development paradigm, as it wagers for a poverty and wealth conception that is not limited to the accumulation of material goods, but it is an economy aware of its effects on nature and the satisfaction of needs and the decolonizing of knowledge. Nevertheless, it is characterized by an operationalization deficit that is shown through the difficulty to establish specific policies and accurate indicators of measurement.

  2. Personal, particular y político: la producción del bien público en la práctica política cotidiana

    Directory of Open Access Journals (Sweden)

    Victoria Ortiz de Rozas

    Full Text Available Resumo El objetivo del artículo es estudiar, a través de la actividad de quienes ocupan cargos políticos, las prácticas concretas que intervienen en la producción del “bien público”, entendido como la distribución de los bienes públicos hacia los ciudadanos. El interés surge de la tensión entre el comportamiento ideal de los políticos –según reglas universales y públicamente orientadas- y una práctica concreta que implica tener en cuenta problemáticas de ciudadanos y grupos sociales determinados, así como los propios intereses políticos. Se cuestiona la relación entre impersonalidad e interés público, planteando que la distribución personalizada de los bienes públicos no supone necesariamente su apropiación privada. Se presenta el estudio empírico de la actividad cotidiana de diferentes políticos con distintos cargos electivos, pertenecientes al partido gobernante, en la provincia de Santiago del Estero, cuyo régimen político ha sido caracterizado por la importancia de las relaciones personales y la politización de la burocracia. Siguiendo una estrategia metodológica cualitativa- que recurre a las técnicas de las entrevistas en profundidad y a la observación no participante; se reconstruye su actividad política cotidiana y las nociones de los políticos sobre sus propias prácticas; prestando atención a las formas de vinculación con los ciudadanos y con otros políticos y funcionarios. El artículo muestra que las tareas de los políticos provinciales, involucran el contacto personalizado tanto con los ciudadanos, como con funcionarios de distintos niveles de la administración pública, que les permiten viabilizar la distribución de bienes públicos hacia sus representados; actividades principalmente de carácter informal. Se muestra que, aunque los objetos de sus acciones sean ciudadanos y grupos territoriales determinados –lejos de la ciudadanía concebida en forma abstracta-, ello no es

  3. Hubble's View of Little Blue Dots

    Science.gov (United States)

    Kohler, Susanna

    2018-02-01

    The recent discovery of a new type of tiny, star-forming galaxy is the latest in a zoo of detections shedding light on our early universe. What can we learn from the unique little blue dots found in archival Hubble data?Peas, Berries, and DotsGreen pea galaxies identified by citizen scientists with Galaxy Zoo. [Richard Nowell Carolin Cardamone]As telescope capabilities improve and we develop increasingly deeper large-scale surveys of our universe, we continue to learn more about small, faraway galaxies. In recent years, increasing sensitivity first enabled the detection of green peas luminous, compact, low-mass (10 billion solar masses; compare this to the Milky Ways 1 trillion solar masses!) galaxies with high rates of star formation.Not long thereafter, we discovered galaxies that form stars similarly rapidly, but are even smaller only 330 million solar masses, spanning less than 3,000 light-years in size. These tiny powerhouses were termed blueberries for their distinctive color.Now, scientists Debra and Bruce Elmegreen (of Vassar College and IBM Research Division, respectively) report the discovery of galaxies that have even higher star formation rates and even lower masses: little blue dots.Exploring Tiny Star FactoriesThe Elmegreens discovered these unique galaxies by exploring archival Hubble data. The Hubble Frontier Fields data consist of deep images of six distant galaxy clusters and the parallel fields next to them. It was in the archival data for two Frontier Field Parallels, those for clusters Abell 2744 and MAS J0416.1-2403, that the authors noticed several galaxies that stand out as tiny, bright, blue objects that are nearly point sources.Top: a few examples of the little blue dots recently identified in two Hubble Frontier Field Parallels. Bottom: stacked images for three different groups of little blue dots. [Elmegreen Elmegreen 2017]The authors performed a search through the two Frontier Field Parallels, discovering a total of 55 little blue dots

  4. Quantum dot-sized organic fluorescent dots for long-term cell tracing

    Science.gov (United States)

    Li, Kai; Tang, Ben Zhong; Liu, Bin

    2014-03-01

    Fluorescence techniques have been extensively employed to develop non-invasive methodologies for tracking and understanding complex biological processes both in vitro and in vivo, which is of high importance in modern life science research. Among a variety of fluorescent probes, inorganic semiconductor quantum dots (QDs) have shown advantages in terms of better photostability, larger Stokes shift and more feasible surface functionalization. However, their intrinsic toxic heavy metal components and unstable fluorescence at low pH greatly impede the applications of QDs in in vivo studies. In this work, we developed novel fluorescent probes that can outperform currently available QD based probes in practice. Using conjugated oligomer with aggregation-induced emission characteristics as the fluorescent domain and biocompatible lipid-PEG derivatives as the encapsulation matrix, the obtained organic dots have shown higher brightness, better stability in biological medium and comparable size and photostability as compared to their counterparts of inorganic QDs. More importantly, unlike QD-based probes, the organic fluorescent dots do not blink, and also do not contain heavy metal ions that could be potentially toxic when applied for living biosubstrates. Upon surface functionalization with a cell-penetrating peptide, the organic dots greatly outperform inorganic quantum dots in both in vitro and in vivo long-term cell tracing studies, which will be beneficial to answer crucial questions in stem cell/immune cell therapies. Considering the customized fluorescent properties and surface functionalities of the organic dots, a series of biocompatible organic dots will be developed to serve as a promising platform for multifarious bioimaging tasks in future.

  5. Nonequilibrium transport of helical Luttinger liquids through a quantum dot

    Science.gov (United States)

    Chao, Sung-Po; Silotri, Salman A.; Chung, Chung-Hou

    2013-08-01

    We study a steady-state nonequilibrium transport between two interacting helical edge states of a two-dimensional topological insulator, described by helical Luttinger liquids, through a quantum dot. For a noninteracting dot, the current is obtained analytically by including the self-energy correction to the dot's Green function. For an interacting dot, we use the equation-of-motion method to study the influence of weak on-site Coulomb interaction on the transport. We find the metal-to-insulator quantum phase transition for attractive or repulsive interactions in the leads when the magnitude of the interaction strength characterized by a charge sector Luttinger parameter K goes beyond a critical value. The critical Luttinger parameter Kcr depends on the hopping strengths between the dot and the leads, as well as the energy level of the dot with respect to the Fermi levels of the leads, ranging from the weak-interaction regime for the dot level off-resonance to the strong-interaction regime for the dot in resonance with the equilibrium Fermi level. Near the transition, there are various singular behaviors of current noise, dot density of state, and the decoherence rate (inverse of lifetime) of the dot, which are briefly discussed.

  6. Imaging Electrons in Few-Electron Quantum Dots

    Science.gov (United States)

    Fallahi, P.; Hanson, M.

    2005-03-01

    Single-electron quantum dots are important candidates for quantum information processing. We have developed a new technique to image electrons inside a single-electron quantum dot in the Coulomb blockade regime, using a scanning probe microscope (SPM) at liquid He temperatures (1). A single-electron quantum dot was formed in a two-dimensional electron gas (2DEG) inside a GaAs/AlGaAs heterostructure by surface gates. Spatial images of an electron inside the dot were obtained by fixing the tip voltage and recording the dot conductance while scanning the SPM tip above the quantum dot. The images show a ring of increased conductance about the center of the dot, where the dot conductance is on the Coulomb blockade conductance peak between 0 and 1 electrons. Simulations show that this technique can be used to extract the wavefunction of electrons inside the dot if the tip perturbation is narrower than the wave function (2). A charged SPM tip promised to be a useful tool for manipulating electrons in quantum dot circuits. 1) P. Fallahi, A.C. Bleszynski, et al submitted to Nanoletters. 2) P. Fallahi, et al Proc. 27 Int. Conf. on Physics and Semiconductors (ICPS27), Flagstaff, July 26-30, 2004, in press. *This work was supported at Harvard University by DARPA DAAD19-01-1-0659 and by the NSEC, NSF PHY-01-17795, and at UCSB by QUEST NSF Science and Technology Center.

  7. ¿Serían la Guardia, Tutela y Curatela Bienes Jurídicos Penales? Un Análisis Crítico de los Arts. 248 y 249 del CP a la Luz de la Exclusiva Protección de Bienes Jurídicos

    Directory of Open Access Journals (Sweden)

    Gerson Faustino Rosa

    2015-12-01

    Full Text Available El presente trabajo tiene por objeto el análisis crítico y la explotación de un importante problema político-criminal de la actualidad: la criminalización de conductas que afrontan la guarda, la tutela y la curatela en el Código Penal, en sus artículos 248 y 249, lo que ya no tiene sentido ante la actual función del sistema penal, criticándose la actividad desenfrenada del Poder Legislativo, que produce ley espenales que no protegen bien jurídico alguno,oque salvaguardan bienes pasibles de protección por otras esferas del Derecho, valiéndose de la fuerza simbólico-comunicativa del Derecho Penal de forma desnecesaria, ampliando demasiadamente el alcance de la pena criminal, hasta el punto de vulgarizar todo el sistema jurídico penalenrazón de su uso indiscriminado. Paraello, enprimer plano,este estudio trata de la política criminal relativa a la libre planificación familiar, criticando la intervención estatal en cuestiones familiares, como ocurre en el Código Penal de 1940, destacando la necesidad de respetarse los principios de intervención mínima y de proporcionalidad antes de que el legislador se valga de la injerencia penal para la protección de cualquier bien jurídico. Más adelante, se presenta la importancia del bien jurídico-penal, con énfasis en la familia como bien jurídico categorial, especialmente la guardia, tutela y curatela, supuestamente lesionadas por los delitos de los artículos 248 y 249 del Código Penal. Así, se analizan brevemente los tipos penales citados, criticándose dicha criminalización, teniéndose en cuenta que tales tipos son subsidiarios, perfectamente prescindibles en el ordenamiento jurídico-penal y pasibles de salvaguardia por el Derecho Civil, que en la solución de los conflictos familiares se muestra mucho más eficaz que la intervención penal.

  8. 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

  9. DotKnot: pseudoknot prediction using the probability dot plot under a refined energy model

    Science.gov (United States)

    Sperschneider, Jana; Datta, Amitava

    2010-01-01

    RNA pseudoknots are functional structure elements with key roles in viral and cellular processes. Prediction of a pseudoknotted minimum free energy structure is an NP-complete problem. Practical algorithms for RNA structure prediction including restricted classes of pseudoknots suffer from high runtime and poor accuracy for longer sequences. A heuristic approach is to search for promising pseudoknot candidates in a sequence and verify those. Afterwards, the detected pseudoknots can be further analysed using bioinformatics or laboratory techniques. We present a novel pseudoknot detection method called DotKnot that extracts stem regions from the secondary structure probability dot plot and assembles pseudoknot candidates in a constructive fashion. We evaluate pseudoknot free energies using novel parameters, which have recently become available. We show that the conventional probability dot plot makes a wide class of pseudoknots including those with bulged stems manageable in an explicit fashion. The energy parameters now become the limiting factor in pseudoknot prediction. DotKnot is an efficient method for long sequences, which finds pseudoknots with higher accuracy compared to other known prediction algorithms. DotKnot is accessible as a web server at http://dotknot.csse.uwa.edu.au. PMID:20123730

  10. 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.

  11. Quantum Dot Devices for Optical Signal Processing

    DEFF Research Database (Denmark)

    Chen, Yaohui

    with other semiconductor materials. The understanding of such properties is important in order to improve the performance of existing devices and to trigger the development of new semiconductor devices for dierent optical signal processing functionalities in the future. We present a detailed quantum dot...... and the continuum. Additional to the conventional time-domain modeling scheme, a small-signal perturbation analysis has been used to assist the investigation of harmonic modulation properties. The static properties of quantum dot devices, for example high saturation power, have been quantitatively analyzed....... 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...

  12. 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.

  13. 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.

  14. Silicon Quantum Dots for Quantum Information Processing

    Science.gov (United States)

    2013-11-01

    16 2.2.2 Si/SiGe Heterostructures . . . . . . . . . . . . . . . . . . . 18 2.2.3 Silicon Nanowires ...Recently, silicon MOS, silicon/silicon- germanium (Si/SiGe) heterostructures and silicon nanowire architectures have also achieved spin manipulation and...Churchill, D. J. Reilly, J. Xiang, C. M. Lieber, and C. M. Marcus. A Ge/Si heterostructure nanowire -based double quantum dot with integrated charge

  15. Transverse dipole spin modes in quantum dots

    Science.gov (United States)

    Lipparini, E.; Barranco, M.; Emperador, A.; Pi, M.; Serra, Ll.

    1999-09-01

    We have carried out a systematic analysis of the transverse dipole spin response of a large-size quantum dot within time-dependent current density functional theory. Results for magnetic fields corresponding to integer filling factors are reported, as well as a comparison with the longitudinal dipole spin response. As in the two-dimensional electron gas, the spin response at high-spin magnetization is dominated by a low-energy transverse mode.

  16. Spin response of unpolarized quantum dots

    Science.gov (United States)

    Serra, L.; Lipparini, E.

    1997-12-01

    The spin response function for electrons confined in a quantum dot is studied within the time-dependent local spin density approximation (TDLSDA) of density functional theory. In the long-wavelength regime we predict the existence of a low-energy collective dipole (ell = 1) spin mode. The evolution with electron number of the spin response is studied and compared with that of the density response. Predictions for the static dipole polarizability are given.

  17. Plasmon assisted photonic crystal quantum dot sensors

    Science.gov (United States)

    Shenoi, R. V.; Ramirez, D. A.; Sharma, Y.; Attaluri, R. S.; Rosenberg, J.; Painter, O. J.; Krishna, S.

    2007-09-01

    We report Quantum Dot Infrared Detectors (QDIP) where light coupling to the self assembled quantum dots is achieved through plasmons occurring at the metal-semiconductor interface. The detector structure consists of an asymmetric InAs/InGaAs/GaAs dots-in-a-well (DWELL) structure and a thick layer of GaAs sandwiched between two highly doped n-GaAs contact layers, grown on a semi-insulating GaAs substrate. The aperture of the detector is covered with a thin metallic layer which along with the dielectric layer confines light in the vertical direction. Sub-wavelength two-dimensional periodic patterns etched in the metallic layer covering the aperture of the detector and the active region creates a micro-cavity that concentrate light in the active region leading to intersubband transitions between states in the dot and the ones in the well. The sidewalls of the detector were also covered with metal to ensure that there is no leakage of light into the active region other than through the metal covered aperture. An enhanced spectral response when compared to the normal DWELL detector is obtained despite the absence of any aperture in the detector. The spectral response measurements show that the Long Wave InfraRed (LWIR) region is enhanced when compared to the Mid Wave InfraRed (MWIR) region. This may be due to coupling of light into the active region by plasmons that are excited at the metal-semiconductor interface. The patterned metal-dielectric layers act as an optical resonator thereby enhancing the coupling efficiency of light into the active region at the specified frequency. The concept of plasmon-assisted coupling is in principle technology agnostic and can be easily integrated into present day infrared sensors.

  18. Biomedical and biological applications of quantum dots.

    Science.gov (United States)

    Abbasi, Elham; Kafshdooz, Tayebeh; Bakhtiary, Mohsen; Nikzamir, Nasrin; Nikzamir, Nasim; Nikzamir, Mohammad; Mohammadian, Mozhdeh; Akbarzadeh, Abolfazl

    2016-05-01

    Quantum dots (QDs) as colloidal nanocrystalline semiconductors have exceptional photophysical properties, due to their quantum confinement effects. Depending on their sizes and chemical compositions, QDs emit different wavelengths over a broad range of the light spectrum, from visible to infrared. QDs are typically extensively used for optical applications due to their high extinction coefficient. This article reviews biomedical applications of QDs, especially the application of QDs in cell targeting, delivery, diagnostics, cancer therapy, and imaging for cancer research.

  19. 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.

  20. Dark pulse quantum dot diode laser.

    Science.gov (United States)

    Feng, Mingming; Silverman, Kevin L; Mirin, Richard P; Cundiff, Steven T

    2010-06-21

    We describe an operating regime for passively mode-locked quantum dot diode laser where the output consists of a train of dark pulses, i.e., intensity dips on a continuous background. We show that a dark pulse train is a solution to the master equation for mode-locked lasers. Using simulations, we study stability of the dark pulses and show they are consistent with the experimental results.

  1. 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.

  2. Biocompatible yogurt carbon dots: evaluation of utilization for medical applications

    Science.gov (United States)

    Dinç, Saliha; Kara, Meryem; Demirel Kars, Meltem; Aykül, Fatmanur; Çiçekci, Hacer; Akkuş, Mehmet

    2017-09-01

    In this study, carbon dots (CDs) were produced from yogurt, a fermented milk product, via microwave-assisted process (800 W) in 30 min without using any additional chemical agents. Yogurt CDs had outstanding nitrogen and oxygen ratios. These dots were monodisperse and about 2 nm sized. The toxicological assessments of yogurt carbon dots in human cancer cells and normal epithelial cells and their fluorescence imaging in living cell system were carried out. Yogurt carbon dots had intense fluorescent signal under confocal microscopy and good fluorescence stability in living cell system. The resulting yogurt carbon dots exhibited high biocompatibility up to 7.1 mg/mL CD concentration which may find utilization in medical applications such as cellular tracking, imaging and drug delivery. Yogurt carbon dots have potential to be good diagnostic agents to visualize cancer cells which may be developed as a therapeutic carrier.

  3. Collective Rabi dynamics of electromagnetically coupled quantum-dot ensembles

    Science.gov (United States)

    Glosser, Connor; Shanker, B.; Piermarocchi, Carlo

    2017-09-01

    Rabi oscillations typify the inherent nonlinearity of optical excitations in quantum dots. Using an integral kernel formulation to solve the three-dimensional Maxwell-Bloch equations in ensembles of up to 104 quantum dots, we observe features in Rabi oscillations due to the interplay of nonlinearity, nonequilibrium excitation, and electromagnetic coupling between the dots. This approach allows us to observe the dynamics of each dot in the ensemble without resorting to spatial averages. Our simulations predict synchronized multiplets of dots that exchange energy, dots that dynamically couple to screen the effect of incident external radiation, localization of the polarization due to randomness and interactions, as well as wavelength-scale regions of enhanced and suppressed polarization.

  4. Non-equilibrium Josephson current through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Pala, M.G. [IMEP-MINATEC (UMR CNRS/INPG/UJF), Grenoble (France); Governale, M.; Koenig, J. [Inst. fuer Theoretische Physik III, Ruhr-Univ. Bochum (Germany)

    2007-07-01

    We study transport through a quantum dot weakly coupled to both normal and superconducting leads. To this aim, we generalize a diagrammatic real-time transport theory to account for superconductivity in the leads. In particular, we consider a system consisting of a quantum dot tunnel coupled to one normal and two superconducting leads. A finite voltage can be applied between the normal and the superconducting leads to drive the dot out of equilibrium. The dot is described by a single, spin-degenerate level, with arbitrary Coulomb repulsion U. The tunnel coupling to the superconducting leads induces a coherent superposition of the empty and doubly occupied dot states (proximity effect). In turn, this may mediate a Josephson current between the two superconductors. We find a situation in which the Josephson current is switched on due to the interplay of Coulomb interaction and non-equilibrium in the dot. (orig.)

  5. Non-equilibrium transport in a series of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qingqiang; Xiong Shijie [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2006-11-15

    We investigate non-equilibrium transport properties in a series of quantum dots in which the Kondo resonance is influenced by the coupling between dots. Based on the Anderson Hamiltonian in the strongly interacting limit, we show the splitting of the Kondo resonance at the Fermi surface and the appearance of negative differential conductance when the magnitude of the interdot coupling is in the order of the coupling between the dots and the leads. We illustrate the relationship between the negative differential conductance and the local densities of states at the dots under different biases. We also show the profile of energies of dots in the series when a finite bias is applied. Furthermore, the differences in transport properties between even and odd numbers of quantum dots in the series are investigated.

  6. 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.

  7. Quantum Dots and Their Multimodal Applications: A Review

    Science.gov (United States)

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

    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 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.

  8. Central dot sign in entities other than Caroli disease

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, T.; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Minami, Manabu

    1997-11-01

    The purpose of this study was to describe central dot sign (tiny dots with strong contrast enhancement of the portal vein within dilated hepatic bile ducts on computed tomography) in entities other than Caroli disease, especially in peribiliary cysts with or without autosomal-dominant polycystic kidney disease. Computed tomography in 74 cases of peribiliary cysts and 134 cases of other liver diseases and states possibly showing central dot sign were retrospectively reviewed to examine the central dot sign. In three cases of peribiliary cysts, some part of the liver showed strongly enhanced portal radicles surrounded completely or partially by low-attenuation, enlarged peribiliary cysts, presenting ``central dot sign`` on contrast-enhanced computed tomography. We suggest that in addition to Caroli disease, some other entities and diseases of the liver may demonstrate central dot sign and this sign should not be considered a specific finding of Caroli disease. (author)

  9. 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.

  10. Research Progress of Photoanodes for Quantum Dot Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    LI Zhi-min

    2017-08-01

    Full Text Available This paper presents the development status and tendency of quantum dot sensitized solar cells. Photoanode research progress and its related technologies are analyzed in detail from the three ways of semiconductor thin films, quantum dot co-sensitization and quantum dot doping, deriving from the approach that the conversion efficiency can be improved by photoanode modification for quantum dot sensitized solar cells. According to the key factors which restrict the cell efficiency, the promising future development of quantum dot sensitized solar cells is proposed,for example,optimizing further the compositions and structures of semiconductor thin films for the photoanodes, exploring new quantum dots with broadband absorption and developing high efficient techniques of interface modification.

  11. 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

  12. 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.

  13. 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...

  14. 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

  15. Discriminación de género en el acceso a bienes y servicios en el tráfico mercantil entre privados

    Directory of Open Access Journals (Sweden)

    María Angustias Díaz Gómez

    2015-06-01

    Full Text Available La Directiva 2004/113/CE, y la Ley Orgánica 3/2007 que la traspone representan un avance en el Derecho antidiscriminatorio por razón de género y en concreto al suministro de bienes y servicios. En este trabajo nos centramos en el acceso a los ofertados desde el sector privado de la economía. Apuntamos a la deficiente incorporación en España de algunas disposiciones de la Directiva; a la necesidad de superar el recurso a la nulidad como principal solución de controversias; así como a la conveniencia de que la regulación antidiscriminatoria de derecho privado reciba un tratamiento legislativo transversal, para así hacer eficaz el derecho a la igualdad y el propio derecho del mercado en áreas tan relevantes como la competencia desleal.

  16. ¿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.

  17. Ambivalencias de la migración y el retorno en contextos rurales de Chiapas: Entre las multas y el bien común

    Directory of Open Access Journals (Sweden)

    Germán MARTÍNEZ VELASCO

    2017-01-01

    Full Text Available Convertirse en migrante internacional en el ámbito de una comunidad indígena chiapaneca entra en tensión con los sistemas normativos que en nombre del bien común reclaman participación de sus miembros. Rehusar a cubrir tareas civiles será aceptado mediante el pago de una multa por el candidato a emigrar. De ahí la existencia de esta instancia comunitaria en la regulación de la migración. El retorno pasa por la calificación comunitaria, además de que las iniciativas de los retornados se ven limitadas. Todo lo anterior ocurre en comunidades, en donde la membresía a una comunidad entraña un lazo de identificación cultural.

  18. 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.

  19. Activités humaines, technologies et bien-être : 7e conférence de psychologie ergonomique (EPIQUE) : Bruxelles, 10-12 juillet 2013

    OpenAIRE

    Van De Weerdt, Corinne; Govaere, Virginie; Marc, Jacques

    2014-01-01

    National audience; Ce congrès avait pour but de traiter plusieurs questions d'actualité sur le thème des activités humaines, des technologies et du bien-être, en lien direct avec le travail, en rassemblant la communauté des chercheurs menant des études dans le domaine de la psychologie ergonomique et de l'ergonomie. Les travaux présentés, issus de recherches nationales et internationales, se réfèrent à l'activité humaine telle qu'elle se déploie dans l'activité de travail et l'usage de techno...

  20. In situ electron-beam polymerization stabilized quantum dot micelles.

    Science.gov (United States)

    Travert-Branger, Nathalie; Dubois, Fabien; Renault, Jean-Philippe; Pin, Serge; Mahler, Benoit; Gravel, Edmond; Dubertret, Benoit; Doris, Eric

    2011-04-19

    A polymerizable amphiphile polymer containing PEG was synthesized and used to encapsulate quantum dots in micelles. The quantum dot micelles were then polymerized using a "clean" electron beam process that did not require any post-irradiation purification. Fluorescence spectroscopy revealed that the polymerized micelles provided an organic coating that preserved the quantum dot fluorescence better than nonpolymerized micelles, even under harsh conditions. © 2011 American Chemical Society

  1. Transcending binary logic by gating three coupled quantum dots.

    Science.gov (United States)

    Klein, Michael; Rogge, S; Remacle, F; Levine, R D

    2007-09-01

    Physical considerations supported by numerical solution of the quantum dynamics including electron repulsion show that three weakly coupled quantum dots can robustly execute a complete set of logic gates for computing using three valued inputs and outputs. Input is coded as gating (up, unchanged, or down) of the terminal dots. A nanosecond time scale switching of the gate voltage requires careful numerical propagation of the dynamics. Readout is the charge (0, 1, or 2 electrons) on the central dot.

  2. Quantum dot blueing and blinking enables fluorescence nanoscopy.

    Science.gov (United States)

    Hoyer, Patrick; Staudt, Thorsten; Engelhardt, Johann; Hell, Stefan W

    2011-01-12

    We demonstrate superresolution fluorescence imaging of cells using bioconjugated CdSe/ZnS quantum dot markers. Fluorescence blueing of quantum dot cores facilitates separation of blinking markers residing closer than the diffraction barrier. The high number of successively emitted photons enables ground state depletion microscopy followed by individual marker return with a resolving power of the size of a single dot (∼12 nm). Nanoscale imaging is feasible with a simple webcam.

  3. Sub-monolayer quantum dots in confinement enhanced dots-in-a-well heterostructure

    Science.gov (United States)

    Sengupta, S.; Kim, J. O.; Barve, A. V.; Adhikary, S.; Sharma, Y. D.; Gautam, N.; Lee, S. J.; Noh, S. K.; Chakrabarti, S.; Krishna, S.

    2012-05-01

    We have investigated optical properties and device performance of sub-monolayer quantum dots infrared photodetector with confinement enhancing (CE) barrier and compared with conventional Stranski-Krastanov quantum dots with a similar design. This quantum dots-in-a-well structure with CE barrier enables higher quantum confinement and increased absorption efficiency due to stronger overlap of wavefunctions between the ground state and the excited state. Normal incidence photoresponse peak is obtained at 7.5 μm with a detectivity of 1.2 × 1011 cm Hz1/2 W-1 and responsivity of 0.5 A/W (77 K, 0.4 V, f/2 optics). Using photoluminescence and spectral response measurements, the bandstructure of the samples were deduced semi-empirically.

  4. Influence of semiconductor-dielectric transition border on the electron states in spherical quantum dots.

    CERN Document Server

    Ghazaryan, E M; Sarkisyan, H A

    2002-01-01

    Electron states in spherical quantum dots are studied, taking into account boundary conditions. The threshold habit of level appearance inside the quantum dots is revealed. The electron energy dependences on the quantum dots radius and confinement potential height

  5. 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.

  6. Imaging ligand-gated ion channels with quantum dots

    Science.gov (United States)

    Tomlinson, I. D.; Orndorff, Rebecca L.; Gussin, Hélène; Mason, John N.; Blakely, Randy D.; Pepperberg, David R.; Rosenthal, Sandra J.

    2007-02-01

    In this paper we report two different methodologies for labeling ligand-gated receptors. The first of these builds upon our earlier work with serotonin conjugated quantum dots and our studies with pegilated quantum dots to reduce non specific binding. In this approach a pegilated derivative of muscimol was synthesized and attached via an amide linkage to quantum dots coated in an amphiphillic polymer derivative of poly acrylamide. These conjugates were used to image the GABA C receptor in oocytes. An alternative approach was used to image tissue sections to study nicotinic acetylcholine receptors in the neuro muscular junction with biotinylated Bungerotoxin and streptavidin coated quantum dots.

  7. Core–shell quantum dots: Properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, D., E-mail: vasudevand@rediffmail.com [Electrodics and electrocatalysis division, CSIR-CECRI, Karaikudi 630006 (India); Gaddam, Rohit Ranganathan [Amity Institute of Nanotechnology, Amity University, Noida 201301 (India); Trinchi, Adrian; Cole, Ivan [CSIRO Materials Science and Engineering, Clayton South MDC, 3169 (Australia)

    2015-07-05

    Fluorescent quantum dots (QDs) are semiconducting nanocrystals (NCs) that find numerous applications in areas, such as bio labelling, sensors, lasers, light emitting diodes and medicine. Core–shell quantum dots were developed to improve the photoluminescence efficiency of single quantum dots. Capping their surface with organic ligands as well as their extraction into aqueous media enables their use in sensing applications. The current review highlights the importance and applications of core shell quantum dots as well as their surface modifications and applications in the field of medicine and as sensors for chemical and biochemical analysis.

  8. 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.

  9. Una interpretación metodológica sobre la incorporación de los bienes y servicios culturales al análisis económico

    Directory of Open Access Journals (Sweden)

    Luis Fernando Aguado Quintero

    2012-01-01

    Full Text Available Los bienes y servicios culturales son insumos para ‘producir’ el bien básico de ocio denominado experiencia cultural, en el marco de las ‘funciones de producción’ de los hogares. El origen de esta modelación se puede rastrear desde el pensamiento económico, en el papel otorgado a los bienes y servicios culturales en su contribución a vivir agradablemente, y la dificultad inherente en dos procesos: la medición del valor y la formación del gusto, por lo que a prestigiosos economistas estos les parecieron bienes de escaso interés. Y, desde el análisis económico, en la discusión que incorpora al ocio como objeto de análisis. El artículo contribuye a la literatura de la economía de la cultura integrando en forma coherente y comprensiva el pensamiento económico con el análisis económico a partir del caso concreto de los bienes culturales.

  10. A multifunctional ribonuclease A-conjugated carbon dot cluster nanosystem for synchronous cancer imaging and therapy

    OpenAIRE

    Liu, Huiyang; Wang, Qin; Shen, Guangxia; Zhang, Chunlei; Li, Chao; Ji, Weihang; Wang, Chun; Cui, Daxiang

    2014-01-01

    Carbon dots exhibit great potential in applications such as molecular imaging and in vivo molecular tracking. However, how to enhance fluorescence intensity of carbon dots has become a great challenge. Herein, we report for the first time a new strategy to synthesize fluorescent carbon dots (C-dots) with high quantum yields by using ribonuclease A (RNase A) as a biomolecular templating agent under microwave irradiation. The synthesized RNase A-conjugated carbon dots (RNase A@C-dots) exhibited...

  11. 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 are not affected by local field fluctuations and using high-energy excitation, we avoid additional sources of linewidth broadening typically present in single-dot photoluminescence spectra. We observe a strong LO-phonon coupling in InAlGaAs and InGaAs dots, which becomes the dominating contribution...

  12. ¿qué papel juega la definición de la eudaimonía en la concepción del bien humano de aristóteles?

    OpenAIRE

    Velásquez, Beatríz Alejandra

    2012-01-01

    Aristóteles propone una concepción del bien humano que determina (hasta con un cierto grado de precisión) cómo hemos de ser, actuar y en general vivir. Tal concepción se logra, según él, definiendo el bien humano, y en EN 1.7 lo define como “una actividad del alma según la virtud”. Esta definición no brinda información acerca de cómo ser y actuar, por lo que parece no contener la concepción esperada del bien, lo cual sí logra la teoría de la virtud presentada en libros posteriores. ¿Qué papel...

  13. La doctrine kantienne du bien et du souverain bien.

    OpenAIRE

    Giraud, Thomas

    2013-01-01

    Even though the question of the highest good and what it consists in lay at the basis of the Ancients ' moral systems, it seems to have gone out of fashion in the Modern era. However, according to Kant, man cannot will anything but under the idea of good and, in order to be able to bring the series of his ends to a close, he needs to conceive the idea of an unconditioned end of his, the "highest good". By tackling the problem of the universal meaning of human life, Kant pays tribute to an anc...

  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. Anisotropic Pauli spin blockade in hole quantum dots

    NARCIS (Netherlands)

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

    2016-01-01

    We present measurements on gate-defined double quantum dots in Ge-Si core-shell nanowires, which we tune to a regime with visible shell filling in both dots. We observe a Pauli spin blockade and can assign the measured leakage current at low magnetic fields to spin-flip cotunneling, for which we

  16. Andreev molecules in semiconductor nanowire double quantum dots

    NARCIS (Netherlands)

    Su, Zhaoen; Tacla, Alexandre B.; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R.; Bakkers, E.P.A.M.; Daley, Andrew J.; Pekker, David; Frolov, Sergey M.

    2017-01-01

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum

  17. A Multi-Channel Speckle Imaging System for the DOT

    NARCIS (Netherlands)

    Sütterlin, P.; Hammerschlag, R.H.; Bettonvil, F.C.M.; Rutten, R.J.; Skomorovsky, V.I.; Domyshev, G.N.

    1995-01-01

    The Dutch Open Telescope (DOT) had its initial observing campaign in September 1999. Although only a simple video system was used, the results demonstrated the excellent high-resolution capabilities of the combination of the open-telescope concept, the DOT optics, the La Palma site, and the

  18. A Multi-Chanel Speckle Imaging for the DOT

    NARCIS (Netherlands)

    Sütterlin, P.; Hammerschlag, R.H.; Bettonvil, F.C.M.; Rutten, R.J.; Skomorovsky, V.I.; Domyshev, G.N.

    2000-01-01

    The Dutch Open Telescope (DOT) had its initial observing campaighn in September 1999. Alhough only a simple video system was used, the results demonstrated the excellent high-resolution capabilities of the combination of the open-teloscope concept, the DOT optics, the remaining image degradation due

  19. Electron transport and coherence in semiconductor quantum dots and rings

    NARCIS (Netherlands)

    Van der Wiel, W.G.

    2002-01-01

    A number of experiments on electron transport and coherence in semiconductor vertical and lateral quantum dots and semiconductor rings is described. Quantum dots are often referred to as "artificial atoms", because of their similarities with real atoms. Examples of such atom-like properties that

  20. Andreev molecules in semiconductor nanowire double quantum dots.

    Science.gov (United States)

    Su, Zhaoen; Tacla, Alexandre B; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Daley, Andrew J; Pekker, David; Frolov, Sergey M

    2017-09-19

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum dots are defined by gate voltages in indium antimonide nanowires. High transparency superconducting niobium titanium nitride contacts are made to each of the dots in order to induce superconductivity, as well as probe electron transport. Andreev bound states induced on each of dots hybridize to define Andreev molecular states. The evolution of these states is studied as a function of charge parity on the dots, and in magnetic field. The experiments are found in agreement with a numerical model.Quantum dots in a nanowire are one possible approach to creating a solid-state quantum simulator. Here, the authors demonstrate the coupling of electronic states in a double quantum dot to form Andreev molecule states; a potential building block for longer chains suitable for quantum simulation.

  1. Behavior of optical bistability in multifold quantum dot molecules

    Science.gov (United States)

    Hamedi, H. R.; Mehmannavaz, M. R.

    2015-02-01

    We analyze the optical bistability (OB) behavior in a multifold quantum dot (QD) molecule composed of five quantum dots controlled by the tunneling coupling. It is shown that the optical bistability can strongly be affected by the tunneling inter-dot coupling coefficients as well as detuning parameters. In addition, we find that the rate of an incoherent pump field has a leading role in modification of the OB threshold. We then generalize our analysis to the case of multifold quantum dot molecules where the number of the quantum dots is N (with a center dot and N-1 satellite dots). We compare the OB features that could occur in a multifold QD system consist of three (N= ), four (N=\\text{4} ), and five (N = 5) quantum dots. We realize that the OB threshold increases as the number of satellite QDs increases. Such controllable optical bistability in multiple QD molecules may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.

  2. The Wigner molecule in a 2D quantum dot

    OpenAIRE

    Akman, N.; Tomak, M.

    1999-01-01

    The charge density and pair correlation function of three interacting electrons confined within a two-dimensional disc-like hard wall quantum dot are calculated by full numerical diagonalization of the Hamiltonian. The formation of a Wigner-molecule in the form of equilateral triangular configuration for electrons is observed as the size of the dot is increased.

  3. MnDOT Library strategic plan : final report.

    Science.gov (United States)

    2017-06-01

    MnDOTs Senior Leadership asked MnDOT Library to develop a Strategic Plan that identifies and reviews the challenges facing the Library over the next five years to better address the evolving needs of the department and users. The strategic plan is...

  4. Electron spin and charge in semiconductor quantum dots

    NARCIS (Netherlands)

    Elzerman, J.M.

    2004-01-01

    In this thesis, the spin and charge degree of freedom of electrons in semiconductor lateral and vertical quantum dots are experimentally investigated. The lateral quantum dot devices are defined in a two-dimensional electron gas (2DEG) below the surface of a GaAs/AlGaAs heterostructure, by metallic

  5. Synthesis of Cesium Lead Halide Perovskite Quantum Dots

    Science.gov (United States)

    Shekhirev, Mikhail; Goza, John; Teeter, Jacob D.; Lipatov, Alexey; Sinitskii, Alexander

    2017-01-01

    Synthesis of quantum dots is a valuable experiment for demonstration and discussion of quantum phenomena in undergraduate chemistry curricula. Recently, a new class of all-inorganic perovskite quantum dots (QDs) with a formula of CsPbX[subscript 3] (X = Cl, Br, I) was presented and attracted tremendous attention. Here we adapt the synthesis of…

  6. 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 offe...

  7. Stark effect and polarizability of graphene quantum dots

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm

    2017-01-01

    The properties of graphene quantum dots can be manipulated via lateral electric fields. Treating electrons in such structures as confined massless Dirac fermions, we derive an analytical expression for the quadratic Stark shift valid for arbitrary angular momentum and quantum dot size. Moreover, we...

  8. 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

  9. Ultrafast gain and index dynamics in quantum dot amplifiers

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Mørk, Jesper

    1999-01-01

    The ultrafast dynamics of gain and refractive index in an InAs/GaAs quantum dot amplifier are investigated at room temperature. The gain is observed to recover with a 90 fs time constant, ruling out problems of slow carrier capture into the dots, and making this component promising for high...

  10. 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 lum...

  11. 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 dev...

  12. Biexciton in nanoheterostructures of germanium quantum dots

    Science.gov (United States)

    Pokutnyi, Sergey I.

    2017-06-01

    The theory of biexciton (formed from spatially separated electrons and holes) in a nanosystem consisting of double quantum dots (QDs) of germanium synthesized in a silicon matrix is presented. It is shown that the major contribution to the biexciton binding energy is made by the energy of the exchange interaction of electrons with holes and this contribution is much more substantial than the contribution of the energy of Coulomb interaction between the electrons and holes. The position of the biexciton state energy band depends both on the mean radius of the QDs and the distance between their surfaces, which enables one to purposefully control it by varying these parameters of the nanostructure.

  13. Protease sensing using nontoxic silicon quantum dots

    Science.gov (United States)

    Cheng, Xiaoyu; McVey, Benjamin F. P.; Robinson, Andrew B.; Longatte, Guillaume; O'Mara, Peter B.; Tan, Vincent T. G.; Thordarson, Pall; Tilley, Richard D.; Gaus, Katharina; Justin Gooding, John

    2017-08-01

    Herein is presented a proof-of-concept study of protease sensing that combines nontoxic silicon quantum dots (SiQDs) with Förster resonance energy transfer (FRET). The SiQDs serve as the donor and an organic dye as the acceptor. The dye is covalently attached to the SiQDs using a peptide linker. Enzymatic cleavage of the peptide leads to changes in FRET efficiency. The combination of interfacial design and optical imaging presented in this work opens opportunities for use of nontoxic SiQDs relevant to intracellular sensing and imaging.

  14. Self-polarization in spherical quantum dot

    Directory of Open Access Journals (Sweden)

    Stojanović Dušanka P.

    2015-01-01

    Full Text Available The electronic structures of CdS quantum dot (QD with dielectric mismatch are calculated. Poisson equation is solved analitically in case of point charge placed inside semiconductor sphere embeded in dielectric matrix in case of different values of the dielectric permittivity of QD and matrix. The validity of the effective mass approximation for the conduction band is assumed. Schrödinger equation for one electron is solved analitically. On the basis of the Poisson equation solution self potential is examined and used as perturbation to calculate the self-polarization effect.

  15. Polymorphic Architectures of Graphene Quantum Dots.

    Science.gov (United States)

    Kim, Sejung; Song, Youngjun; Heller, Michael J

    2017-08-01

    A systematic strategy for designing structured nanomaterials is demonstrated through self-assembly of graphene quantum dots. The approach reveals that graphene derivatives at the nanoscale assemble into various architectures of nanocrystals in a binary solution system. The shapes of the nanocrystals continue to evolve in terms of the intimate association of organic molecules with the dispersion medium, obtaining a high index faceted superlattice. This facile synthetic process provides a versatile strategy for designing particles to new structured materials systems, exploiting the crystallization of layered graphitic carbon structures within single crystals. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

  17. Quantum Dots in Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Sollner, Immo Nathanael

    of this Thesis we discuss a novel type of photonic crystal waveguide and show its applications for on-chip quantum information processing. This structure was designed for the ecient mapping of two orthogonal circular dipole transitions to dierent propagation paths of the emitted photon, i.e. exhibits chiral...... 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....

  18. 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.

  19. 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

  20. 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.

  1. Non-Markovian coherent feedback control of quantum dot systems

    Science.gov (United States)

    Xue, Shibei; Wu, Rebing; Hush, Michael R.; Tarn, Tzyh-Jong

    2017-03-01

    In this paper we present a non-Markovian coherent feedback scheme for decoherence suppression in single quantum dot systems. The feedback loop is closed via a quantum tunnelling junction between the natural source and drain baths of the quantum dot. The exact feedback-controlled non-Markovian Langevin equation is derived for describing the dynamics of the quantum dot. To deal with the nonlinear memory function in the Langevin equation, we analyse the Green’s function-based root locus, from which we show that the decoherence of the quantum dot can be suppressed via increasing the feedback coupling strength. The effectiveness of decoherence suppression induced by non-Markovian coherent feedback is demonstrated by a single quantum dot example bathed with Lorentzian noises.

  2. 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......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...... with second-order correlation measurements and a theoretical model. We measure an oscillator strength of up to 960:8 and an average quantum eciency of (94:83:0)%. This enhanced light-matter coupling is known as the giant oscillator strength of quantum dots, which is shown to be equivalent to superradiance. We...

  3. Stochastic clustered-dot screen design for improved smoothness

    Science.gov (United States)

    Gupta, Madhur; Goyal, Puneet; Fischer, Mani; Staelin, Carl; Kashti, Tamar; Shacham, Omri; Allebach, Jan

    2011-01-01

    Printers employing electrophotographic technology typically use clustered-dot screening to avoid potential artifacts caused by unstable dot rendering. Periodic clustered-dot screens are quite smooth, but also suffer from periodic moiŕe artifacts due to interference with other color channels. Stochastic, clustered-dot screens provide an alternative solution. In this paper, we introduce a new approach for stochastic, clustered-dot screen design based on Direct Binary Search (DBS). The method differs from the conventional DBS in its use of a modified cost metric which was derived in an earlier work from using different filters in the initialization and update phases of DBS. The objective of the chosen approach is to design screen for improved print smoothness by generating a homogeneous distribution of compact, uniformly-sized clusters. The results include halftone of a screened folded-ramp, compared against a screen designed with a previous method.

  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. 3D super-resolution imaging with blinking quantum dots

    Science.gov (United States)

    Wang, Yong; Fruhwirth, Gilbert; Cai, En; Ng, Tony; Selvin, Paul R.

    2013-01-01

    Quantum dots are promising candidates for single molecule imaging due to their exceptional photophysical properties, including their intense brightness and resistance to photobleaching. They are also notorious for their blinking. Here we report a novel way to take advantage of quantum dot blinking to develop an imaging technique in three-dimensions with nanometric resolution. We first applied this method to simulated images of quantum dots, and then to quantum dots immobilized on microspheres. We achieved imaging resolutions (FWHM) of 8–17 nm in the x-y plane and 58 nm (on coverslip) or 81 nm (deep in solution) in the z-direction, approximately 3–7 times better than what has been achieved previously with quantum dots. This approach was applied to resolve the 3D distribution of epidermal growth factor receptor (EGFR) molecules at, and inside of, the plasma membrane of resting basal breast cancer cells. PMID:24093439

  6. 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......The homogeneous linewidth of excitonic transitions is a parameter of fundamental physical importance. In self-assembled quantum dot systems, a strong inhomogeneous broadening due to dot size fluctuations masks the homogeneous linewidth associated with transitions between individual states...... to fast dephasing. We present an investigation of the low-temperature homogeneous linewidth of individual PL lines from MBE-grown In0.5Ga0.5As/GaAs quantum dots....

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

    DEFF Research Database (Denmark)

    Madsen, Kristian Høeg

    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...... 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...

  8. Germanium based electrostatic quantum dots: design and characterization.

    Science.gov (United States)

    Mazzeo, Giovanni; Yablonovitch, Eli; Jiang, Hong-Wen

    2010-03-01

    While the less mature Germanium technology requires an extra effort for the realization of single electron quantum dots, unique properties of Germanium rich heterostructures together with spin coherence times comparable to Silicon, can justify the development of such new technology. We report our progresses on the formation of electrostatic quantum dots in Germanium. We employ an MOS-like structure with no modulation doping already successfully proven in Silicon devices. A two level gate stack is used: the top gate is positively biased to attract electrons while the lowers gates are negatively biased to form the quantum dot and attract holes in a transistor channel, used to detect the electrons in the adjacent quantum dot. Finite Element Method simulations are used to prove the concept of this hybrid holes-transistor/electron-QD device and estimate the sensitivity of the charge detection. Preliminary characterizations of quantum dot devices built with this structure are reported.

  9. Visible-Light-Activated Bactericidal Functions of Carbon "Quantum" Dots.

    Science.gov (United States)

    Meziani, Mohammed J; Dong, Xiuli; Zhu, Lu; Jones, Les P; LeCroy, Gregory E; Yang, Fan; Wang, Shengyuan; Wang, Ping; Zhao, Yiping; Yang, Liju; Tripp, Ralph A; Sun, Ya-Ping

    2016-05-04

    Carbon dots, generally defined as small carbon nanoparticles with various surface passivation schemes, have emerged as a new class of quantum-dot-like nanomaterials, with their optical properties and photocatalytic functions resembling those typically found in conventional nanoscale semiconductors. In this work, carbon dots were evaluated for their photoinduced bactericidal functions, with the results suggesting that the dots were highly effective in bacteria-killing with visible-light illumination. In fact, the inhibition effect could be observed even simply under ambient room lighting conditions. Mechanistic implications of the results are discussed and so are opportunities in the further development of carbon dots into a new class of effective visible/natural light-responsible bactericidal agents for a variety of bacteria control applications.

  10. Relaxation of a Hole Spin in a Quantum Dot.

    Science.gov (United States)

    Woods, L. M.; Reinecke, T. L.; Kotlyar, R.

    2004-03-01

    Theoretical results for relaxation of the spin of a hole in cylindrical quantum dots due to acoustic phonon assisted flips at low temperatures with an applied magnetic field are presented. The hole dispersion is calculated by numerical diagonalization of the Luttinger Hamiltonian and applying perturbation theory with respect to the magnetic field,and the hole-phonon coupling is described by the Bir-Pikus Hamiltonian. We find that the decoherence time for hole spins for dots < ˜ 20 nm is on the order of 10-8 s. This is several orders smaller than the decoherence time due to phonon assisted processes for electron spins in similar dots and is comparable to the total decoherence time of an electron spin in a quantum dot, which is controlled by the hyperfine interaction with nuclei. We obtain the dependence of the relaxation rate of the hole spin on dot size, hole mass.

  11. Carbon dots based FRET for the detection of DNA damage.

    Science.gov (United States)

    Kudr, Jiri; Richtera, Lukas; Xhaxhiu, Kledi; Hynek, David; Heger, Zbynek; Zitka, Ondrej; Adam, Vojtech

    2017-06-15

    Here, we aimed our attention at the synthesis of carbon dots (C-dots) with the ability to interact with DNA to suggest an approach for the detection of DNA damage. Primarily, C-dots modified with amine moieties were synthesized using the one-step microwave pyrolysis of citric acid in the presence of diethylenetriamine. The C-dots showed strong photoluminescence with a quantum yield of 4%. In addition, the C-dots (2.8±0.8nm) possessed a good colloidal stability and exhibited a positive surface charge (ζ=36mV) at a neutral pH. An interaction study of the C-dots and the DNA fragment of λ bacteriophage was performed, and the DNA binding resulted in changes to the photoluminescent and absorption properties of the C-dots. A binding of the C-dots to DNA was also observed as a change to DNA electrophoretic mobility and a decreased ability to intercalate ethidium bromide (EtBr). Moreover, the Förster (or fluorescence) resonance energy transfer (FRET) between the C-dots and EtBr was studied, in which the C-dots serve as an excitation energy donor and the EtBr serves as an acceptor. When DNA was damaged using ultraviolet (UV) radiation (λ=254nm) and hydroxyl radicals, the intensity of the emitted photoluminescence at 612nm significantly decreased. The concept was proved on analysis of the genomic DNA from PC-3 cells and DNA isolated from melanoma tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Luminescent GdVO4:Sm3+ quantum dots enhance power conversion efficiency of bulk heterojunction polymer solar cells by Förster resonance energy transfer

    Science.gov (United States)

    Bishnoi, Swati; Gupta, Vinay; Sharma, Chhavi; Haranath, D.; Naqvi, Sheerin; Kumar, Mahesh; Sharma, Gauri D.; Chand, Suresh

    2016-07-01

    In this work, we report enhanced power conversion efficiency (PCE) of bulk heterojunction polymer solar cells by Förster resonance energy transfer (FRET) from samarium-doped luminescent gadolinium orthovanadate (GdVO4:Sm3+) quantum dots (QDs) to polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) polymer. The photoluminescence emission spectrum of GdVO4:Sm3+ QDs overlaps with the absorption spectrum of PTB7, leading to FRET from GdVO4:Sm3+ to PTB7, and significant enhancements in the charge-carrier density of excited and polaronic states of PTB7 are observed. This was confirmed by means of femtosecond transient absorption spectroscopy. The FRET from GdVO4:Sm3+ QDs to PTB7 led to a remarkable increase in the power conversion efficiency (PCE) of PTB7:GdVO4:Sm3+:PC71BM ([6,6]-phenyl-C71-butyric acid methyl ester) polymer solar cells. The PCE in optimized ternary blend PTB7:GdVO4:Sm3+:PC71BM (1:0.1:1.5) is increased to 8.8% from 7.2% in PTB7:PC71BM. This work demonstrates the potential of rare-earth based luminescent QDs in enhancing the PCE of polymer solar cells.

  13. Optical studies on a single GaAs laterally coupled quantum dot in comparison with an uncoupled quantum dot

    Science.gov (United States)

    Kim, Heedae; Song, Jin Dong

    2018-01-01

    We performed spectroscopy studies on a single GaAs laterally coupled quantum dot and an uncoupled quantum dot. Photoluminescence spectra confirmed the presence of optical coupling in the coupled quantum dot through dipole-dipole interactions. The optical coupling was investigated in terms of the integrated photoluminescence intensities and redshift of emission energies as the excitation power was increased. The excitation intensity was increased with linearly polarized light in the lateral coupling direction 1 1 bar 0 , which resulted in excitons X1 and X2 of the coupled quantum dot showing a clear photoluminescence peak shift to lower energy with drastically different power factors. These results were obtained by integrating the PL spectrum and comparing it to that of a single quantum dot. We also found that the decay rates of X1 and X2 in the coupled quantum dot increased significantly as a consequence of overlap of electron and hole wavefunctions extended via optical coupling in individual dots of the coupled quantum dot system.

  14. 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

  15. Corot, une mission bien remplie

    Science.gov (United States)

    Baglin, Annie; Belkacem, Kevin; Chaintreuil, Sylviane; Deleuil, Magali; Lam-Trong, Thien

    2017-03-01

    The CoRoT mission developped since 1993 was dedicated to the observation of ultra high precision measurements of the variations of stellar fluxed on long and continuous durations. His two major objectives were the detection of stellar oscillations and of extrasolar planets. A a pionnier mission, it had to invent several methods and to built the successive steps of the data treatment. They are rapidly described. The low cost 'CNES Petites Missions" programme imposed severe contraints on the instrument concept (Organisation and management, choice of the detectors, of the orbit, reduction of all parasite lights) which have been and will be guides for new generation projects. Some scientific highlights are then presented on both programmes, as for instance the use of the seismic tool as an indicator of the structure and evolution of the Galaxy, the first detection of a super-Earth, and the first precise characterisation of a brown dwarf . CoRoT has opened several avenues in instrumentation as well as science. It is shown how some aspects of this heritage have been used in the design and development of its two major heiress: CHEOPS to be launched in 2018 and the more ambitious PLATO, to be launched in 2025.

  16. 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.

  17. Macular pseudohaemorrhage secondary to Allen Dot artefact.

    Science.gov (United States)

    Michaels, Luke; Alexander, Philip; Newsom, Richard

    2015-01-05

    A 34-year-old highly myopic (-11.00 D) woman presented to eye clinic with a 3 day history of right eye paracentral blurring. Visual acuities were 6/6 bilaterally. Clinical examination was normal. Fundus photography showed the classic appearance of a macular haemorrhage. This is a recognised complication of high myopia and would have accounted for the patient's symptoms. However, further photography showed that the haemorrhage seemed to 'jump' around the fundus and was even present in the fellow eye. The apparent haemorrhage was revealed to be an imaging artefact. The 'Allen Dot' is a 6 mm black mask incorporated into retinal cameras to reduce reflection. Rarely, in highly myopic eyes, optical artefact can result. To the best of our knowledge, we are the first in the literature to report artefacts from the Allen Dot masquerading as ophthalmic disease. This case re-iterates the importance of clinical examination, especially in high myopes, given the current trend towards virtual clinics. 2015 BMJ Publishing Group Ltd.

  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. 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.

  20. Quantum dots for lasers, amplifiers and computing

    Energy Technology Data Exchange (ETDEWEB)

    Bimberg, Dieter [Technische Universitaet Berlin, Hardenbergstr. 36, 10623, Berlin (Germany)

    2005-07-07

    For InAs-GaAs based quantum dot lasers emitting at 1300 nm, digital modulation showing an open eye pattern up to 12 Gb s{sup -1} at room temperature is demonstrated, at 10 Gb s{sup -1} the bit error rate is below 10{sup -12} at -2 dB m receiver power. Cut-off frequencies up to 20 GHz are realised for lasers emitting at 1.1 {mu}m. Passively mode-locked QD lasers generate optical pulses with repetition frequencies between 5 and 50 GHz, with a minimum Fourier limited pulse length of 3 ps. The uncorrelated jitter is below 1 ps. We use here deeply etched narrow ridge waveguide structures which show excellent performance similar to shallow mesa structures, but a circular far field at a ridge width of 1 {mu}m, improving coupling efficiency into fibres. No beam filamentation of the fundamental mode, low a-factors and strongly reduced sensitivity to optical feedback are observed. QD lasers are thus superior to QW lasers for any system or network. Quantum dot semiconductor optical amplifier (QD SOAs) demonstrate gain recovery times of 120-140 fs, 4-7 times faster than bulk/QW SOAs, and a net gain larger than 0.4 dB/(mm*QD-layer) providing us with novel types of booster amplifiers and Mach-Zehnder interferometers. These breakthroughs became possible due to systematic development of self-organized growth technologies.

  1. 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.

  2. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. 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.

  4. 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.

  5. Photostable fluorescent organic dots with aggregation-induced emission (AIE dots) for noninvasive long-term cell tracing

    Science.gov (United States)

    Li, Kai; Qin, Wei; Ding, Dan; Tomczak, Nikodem; Geng, Junlong; Liu, Rongrong; Liu, Jianzhao; Zhang, Xinhai; Liu, Hongwei; Liu, Bin; Tang, Ben Zhong

    2013-01-01

    Long-term noninvasive cell tracing by fluorescent probes is of great importance to life science and biomedical engineering. For example, understanding genesis, development, invasion and metastasis of cancerous cells and monitoring tissue regeneration after stem cell transplantation require continual tracing of the biological processes by cytocompatible fluorescent probes over a long period of time. In this work, we successfully developed organic far-red/near-infrared dots with aggregation-induced emission (AIE dots) and demonstrated their utilities as long-term cell trackers. The high emission efficiency, large absorptivity, excellent biocompatibility, and strong photobleaching resistance of the AIE dots functionalized by cell penetrating peptides derived from transactivator of transcription proteins ensured outstanding long-term noninvasive in vitro and in vivo cell tracing. The organic AIE dots outperform their counterparts of inorganic quantum dots, opening a new avenue in the development of fluorescent probes for following biological processes such as carcinogenesis.

  6. Acuerdos de pesca en los lagos de Tarapoto: Alternativa de gestión para los bienes comunes en la Amazonia colombiana

    Directory of Open Access Journals (Sweden)

    Catalina Trujillo Osorio

    2017-09-01

    Full Text Available Se presentan las experiencias de gestión de recursos pesqueros en resguardos indígenas del Amazonas colombiano y los resultados y limitaciones del proceso adelantado para la construcción de acuerdos comunitarios de pesca. Se usó la metodología de investigación-acción-participación respondiendo al objetivo de crear estrategias para contrarrestar los problemas de agotamiento del recurso pesquero de los lagos de Tarapoto en el resguardo Ticoya y consolidar estrategias propias para fortalecer la capacidad de gobernanza interna del recurso pesquero dentro del territorio indígena. Se encontró que los acuerdos de pesca actúan como instituciones que regulan y optimizan el uso de bienes comunes de libre acceso, y consolidan la capacidad de gobernanza en territorios indígenas. Se concluye que la consolidación de un sistema propio de gestión debe ir más allá del control del recurso, evidenciando los esfuerzos locales por adoptar sistemas de manejo alternativo que se integren al modo de vida indígena y a los modelos de producción tradicional.

  7. El puerto como territorio: ¿un espacio excepcional o un bien común? Discutiendo la deficiencia en el gobierno del puerto

    Directory of Open Access Journals (Sweden)

    Eric Foulquier

    2012-02-01

    Full Text Available Durante los últimos veinte años, el espacio portuario ha sufrido una verdadera transición. Poco a poco, el modelo de gestión conocido como «Landlord port» se impone como modelo dominante de gestión portuaria en el mundo. En varios países, el Estado concede los terminales a operadores privados y transforma el estatuto de las Autoridades Portuarias. Estas siguen siendo los pilotos de la estrategia de desarrollo portuario, pero pierden toda prerrogativa en materia de explotación. Este retroceso del Estado coloca el espacio portuario en una situación paradójica, entre misión de interés general y defensa de intereses privados. ¿Todavía podemos considerar el puerto como un bien común? Dos visiones de esta comunidad pueden ser enunciadas: una visión económica, una visión cívica.

  8. Medición simplificada del nivel socioeconómico en encuestas breves: propuesta a partir de acceso a bienes y servicios

    Directory of Open Access Journals (Sweden)

    Juan Pablo Gutiérrez

    2015-07-01

    Full Text Available Objetivo. Desarrollar un indicador socioeconómico para encuestas breves que permita una clasificación en relación con un criterio poblacional y que resulte parsimonioso. Material  métodos. Se generó un indicador socioeconómico a partir de variables dicotómicas de bienes y servicios. Se obtuvo la correlación de los resultados obtenidos de la Encuesta Nacional de Ingresos y Gastos en los Hogares ENIGH con los de una encuesta breve y se les comparó con los de un indicador construido a partir de un conjunto mayor de variables. Resultados. La concordancia para los quintiles 1, 2, 3, 4 y 5 del indicador amplio y el parsimonioso son 94, 94, 82, 83 y 89%, respectivamente. El coeficiente de correlación por angos de Spearman fue de 0.85. Conclusiones. El indicador parsimonioso propuesto captura la heterogeneidad del nivel socioeconómico en la encuesta probada. Se sugiere su uso para encuestas breves debido a sus ventajas: a se elabora con variables dicotómicas; b las variables base no implican el cumplimiento de algún supuesto estadístico; c es fácilmente calculado, y d se puede utilizar para comparar grupos.

  9. 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.

  10. 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.

  11. 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.

  12. Pulse train amplification and regeneration based on semiconductor quantum dots waveguide

    DEFF Research Database (Denmark)

    Chen, Yaohui; Öhman, Filip; Mørk, Jesper

    2008-01-01

    We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides.......We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides....

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

    NARCIS (Netherlands)

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

    2016-01-01

    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

  14. Scaling of the Coulomb Energy Due to Quantum Fluctuations in the Charge on a Quantum Dot

    DEFF Research Database (Denmark)

    Molenkamp, L. W; Flensberg, Karsten; Kemerink, M.

    1995-01-01

    The charging energy of a quantum dot is measured through the effect of its potential on the conductance of a second dot. This technique allows a measurement of the scaling of the dot's charging energy with the conductance of the tunnel barriers leading to the dot. We find that the charging energy...

  15. Ivonne Farah H. / Luciano Vasapollo (Coordinadores), Vivir Bien: ¿Paradigma no capitalista?, Universidad Mayor de San Andrés(CIDES-UMSA) y Departamento de Economía de la Universidad de Roma La Sapienza, 2011, 437 p

    National Research Council Canada - National Science Library

    Perea Sandoval, Carlos

    2013-01-01

    ... recíproca con la naturaleza y las demás formas de vida, en el camino de la ética del bien común. La construcción de este modelo ético se constituye en una prioridad ya que desde el mismo es posible determinar caminos...

  16. Preparation of carbon quantum dots based high photostability luminescent membranes.

    Science.gov (United States)

    Zhao, Jinxing; Liu, Cui; Li, Yunchuan; Liang, Jiyuan; Liu, Jiyan; Qian, Tonghui; Ding, Jianjun; Cao, Yuan-Cheng

    2017-06-01

    Urethane acrylate (UA) was used to prepare carbon quantum dots (C-dots) luminescent membranes and the resultants were examined with FT-IR, mechanical strength, scanning electron microscope (SEM) and quantum yields (QYs). FT-IR results showed the polyurethane acrylate (PUA) prepolymer -C = C-vibration at 1101 cm-1 disappeared but there was strong vibration at1687cm-1 which was contributed from the-C = O groups in cross-linking PUA. Mechanical strength results showed that the different quantity of C-dots loadings and UV-curing time affect the strength. SEM observations on the cross-sections of the membranes are uniform and have no structural defects, which prove that the C-dots are compatible with the water-soluble PUA resin. The C-dot loading was increased from 0 to 1 g, the maximum tensile stress was nearly 2.67 MPa, but the tensile strain was decreased from 23.4% to 15.1% and 7.2% respectively. QYs results showed that the C-dots in the membrane were stable after 120 h continuous irradiation. Therefore, the C-dots photoluminescent film is the promising material for the flexible devices in the future applications. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Imaging and magnetotransport in superconductor/magnetic dot arrays

    Science.gov (United States)

    Silevitch, D. M.; Reich, D. H.; Chien, C. L.; Field, S. B.; Shtrikman, H.

    2001-06-01

    Magnetoresistance and scanning Hall probe microscopy studies of Nb-film/Ni-dot structures are reported. The dots act as pinning sites for superconducting vortices. The transport measurements focus on the effects of introducing disorder into the positions of the pinning lattice near the superconducting critical temperature Tc in structures with 250 nm diameter Ni dots randomized about an ideal square lattice with lattice constant a=560 nm. Features observable in the ordered arrays at higher multiples of the matching field H0=Φ0/a2 are washed out in the disordered arrays, but those at H0 remain. Scanning Hall probe microscope images were taken of the vortex configurations at fields up to 1.2H0 in ordered arrays of 1-μm-diameter dots on a 5.2 μm×4 μm rectangular lattice. These show that despite the relatively weak pinning of the magnetic dots, ordering commensurate with the dot lattice occurs even for fields below H0. Both transport and imaging studies point to the importance of interstitial vortices in determining the properties of superconductor/magnetic dot arrays.

  18. Enhanced thermoelectric properties in boron nitride quantum-dot

    Directory of Open Access Journals (Sweden)

    Changning Pan

    Full Text Available We have investigated the ballistic thermoelectric properties in boron nitride quantum dots by using the nonequilibrium Green’s function approach and the Landauer transport theory. The result shows that the phonon transport is substantially suppressed by the interface in the quantum dots. The resonant tunneling effect of electron leads to the fluctuations of the electronic conductance. It enhances significantly the Seebeck coefficient. Combined with the low thermal conductance of phonon, the high thermoelectric figure of merit ZT ∼0.78 can be obtained at room temperature T = 300 K and ZT ∼0.95 at low temperature T = 100 K. It is much higher than that of graphene quantum dots with the same geometry parameters, which is ZT ∼0.29 at room temperature T = 300 K and ZT ∼0.48 at low temperature T = 100 K. The underlying mechanism is that the boron nitride quantum dots possess higher thermopower and lower phonon thermal conductance than the graphene quantum dots. Thus the results indicate that the thermoelectric properties of boron nitride can be significantly enhanced by the quantum dot and are better than those of graphene. Keywords: Thermoelectric properties, Boron nitride quantum dot, Electron transport, Phonon transport

  19. Atomically precise, coupled quantum dots fabricated by cleaved edge overgrowth

    Science.gov (United States)

    Wegscheider, W.; Schedelbeck, G.; Bichler, M.; Abstreiter, G.

    Recent progress in the fabrication of quantum dots by molecular beam epitaxy along three directions in space is reviewed. The optical properties of different sample structures consisting of individual quantum dots, pairs of coupled dots as well as of linear arrays of dots are studied by microscopic photoluminescence spectroscopy. The high degree of control over shape, composition and position of the 7×7×7 nm3 size GaAs quantum dots, which form at the intesection of three orthogonal quantum wells, allows a detailed investigation of the influence of coupling between almost identical zero-dimensional objects. In contrast to the inhomogeneously broadened quantum well and quantum wire signals originating from the complex twofold cleaved edge overgrowth structure, the photoluminescence spetrum of an individual quantum dot exhibits a single sharp line (full width at half maximum denomination "artificial atoms" for the quantum dots. It is further demonstrated that an "artifical molecule", characterized by the existence of bonding and antibonding states can be assembled from two of such "artificial atoms". The coupling strength between the "artificial atoms" is adjusted by the "interatomic" distance and is reflected in the energetic separation of the bonding and antibonding levels and the linewidths of the corresponding interband transitions.

  20. Detection of bioconjugated quantum dots passivated with different ligands for bio-applications.

    Science.gov (United States)

    Singh, Gurpal; Zaidi, Neelam Hazoor; Soni, Udit; Gautam, Manoj; Jackeray, Richa; Singh, Harpal; Sapra, Sameer

    2011-05-01

    Bioconjugation of quantum dots has resulted in a significant increase in resolution of biological fluorescent labeling. This intrinsic property of quantum dots can be utilized for sensitive detection of target analytes with high sensitivity; including pathogenic bacteria and cancer monitoring. The quantum dots and quantum dot doped silica nanoparticles exhibit prominent emission peaks when excited at 400 nm but on conjugation to model rabbit antigoat antibodies exhibit diminished intensity of emission peak at 600 nm. It shows that photoluminescence intensity of conjugated quantum dots and quantum dot doped silica nanoparticles could permit the detection of bioconjugation. Samples of conjugated and unconjugated quantum dots and quantum dot doped silica nanoparticles were subjected to enzyme linked immunosorbent assay for further confirmation of bioconjugation. In the present study ligand exchange, bioconjugation, fluorescence detection of bioconjugated quantum dots and quantum dot doped silica nanoparticles and further confirmation of bioconjugation by enzyme linked immunosorbent assay has been described.

  1. Image enhancement for increased dot-counting efficiency in FISH.

    Science.gov (United States)

    Shah, Shishir

    2007-11-01

    The most commonly used molecular cytogenetic technique is fluorescence in situ hybridization (FISH). It has been widely applied in many areas of diagnosis and research, including pre-natal and post-natal screening of chromosomal aberrations, pre-implantation genetic diagnosis, cancer cytogenetics, gene mapping, molecular pathology and developmental molecular biology. The analysis of FISH images consists of detecting fluorescent dots, after which the number of dots per cell can be counted or their relative positions can be measured. A major impediment in the analysis of FISH specimens is signal (dot) quality, which is influenced by the hybridization efficiency and/or the sensitivity of the camera that records the images. In this paper, we present an approach to improve the efficiency of detecting fluorescent signals in FISH images by recovering the radiance map of the camera. This allows us to generate a high-dynamic-range image wherein an extended range of the sample radiance captured by the camera can be visualized at distinct intensity values. The resulting higher-order numeric complexity of the transformed image is adjusted (or simplified) by examining the intensity distribution in each of the three colour channels (red, green and blue), and remapping the intensity values to generate a high-contrast image with a lower-order (compressed) dynamic range. The remapping is based on a criterion that optimizes the detection of the hybridized signals, allowing attenuation of saturated intensity values while amplifying low-intensity signals. A simple dot-counting algorithm is used to automatically process 2000 FISH images. The images are taken for lymphocytes from cultured blood specimens for cytogenetic testing. Images are manually analyzed by an expert to obtain ground truth for dot counts. A quantitative analysis is performed by comparing results of automated dot detection on images before and after enhancement with the developed algorithms. In addition, common errors

  2. Diffusion Monte Carlo study of circular quantum dots

    Science.gov (United States)

    Pederiva, Francesco; Umrigar, C. J.; Lipparini, E.

    2000-09-01

    We present ground- and excited-state energies obtained from diffusion Monte Carlo (DMC) calculations, using accurate multiconfiguration wave functions, for N electrons (N<=13) confined to a circular quantum dot. We compare the density and correlation energies to the predictions of local spin density approximation (LSDA) theory and Hartree-Fock (HF) theory, and analyze the electron-electron pair-correlation functions. The DMC estimated change in electrochemical potential as a function of the number of electrons in the dot is compared to that from LSDA and HF calculations. Hund's first rule is found to be satisfied for all dots except N=4 for which there is a near degeneracy.

  3. [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.

  4. 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.

  5. State hybridization shapes the photocurrent in triple quantum dot nanojunctions

    Energy Technology Data Exchange (ETDEWEB)

    Beltako, Katawoura; Cavassilas, Nicolas; Michelini, Fabienne [Universités Aix Marseille et Toulon, CNRS, IM2NP, UMR 7334, 13288 Marseille (France)

    2016-08-15

    We investigated a prototype of a quantum dot based photodetector made of a dot absorber interconnected with two lateral dot filters in contact with semiconducting leads. Using the nonequilibrium Green's function technique, we found that there are two opposite evolutions of the photocurrent in the vicinity of the tunnel resonance for such a kind of nanodevice. This evolution depends on where the strongest hybridization of states happens, and hence still reveals a quantum effect. If the filter states hybridize more with the absorber states than the ones of the leads, the photocurrent shows a maximum at the tunnel resonance, while it is minimized in the opposite case.

  6. 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.

  7. 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.

  8. Electron transport in InAs nanowire quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Fuhrer, Andreas [Nanometer Structure Consortium, Lund Universtity, Box 118, S-221 00 Lund (Sweden); School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Fasth, Carina; Samuelson, Lars [Nanometer Structure Consortium, Lund Universtity, Box 118, S-221 00 Lund (Sweden)

    2008-07-01

    We investigate electron transport in single and double quantum dots defined in catalytically grown InAs nanowires containing down to a single electron. We determine g-factor and strength of the spin-orbit interaction directly from excited state measurements in these few electron quantum dots. Using local gates to deplete homogeneous InAs nanowires offers a high degree of tunability for defining double quantum dots. Here we show that such systems are ideally suited to manipulate single spins and charges for electron pumping, charge read-out and spin manipulation applications.

  9. Tunable RKKY interaction in a double quantum dot nanoelectromechanical device

    Science.gov (United States)

    Parafilo, A. V.; Kiselev, M. N.

    2018-01-01

    We propose a realization of mechanically tunable Ruderman-Kittel-Kasuya-Yosida interaction in a double quantum dot nanoelectromechanical device. The coupling between spins of two quantum dots suspended above a metallic plate is mediated by conduction electrons. We show that the spin-mechanical interaction can be driven by a slow modulation of charge density in the metallic plate. We propose to use Stückelberg oscillations as a sensitive tool for detection of the spin and charge states of the coupled quantum dots. Theory of mechanical back action induced by a dynamical spin-spin interaction is discussed.

  10. 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......) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multi-electron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters...... on Coulomb drag in CQD systems....

  11. 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...

  12. 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

  13. Photon-mediated interaction between distant quantum dot circuits.

    Science.gov (United States)

    Delbecq, M R; Bruhat, L E; Viennot, J J; Datta, S; Cottet, A; Kontos, T

    2013-01-01

    Engineering the interaction between light and matter is an important goal in the emerging field of quantum opto-electronics. Thanks to the use of cavity quantum electrodynamics architectures, one can envision a fully hybrid multiplexing of quantum conductors. Here we use such an architecture to couple two quantum dot circuits. Our quantum dots are separated by 200 times their own size, with no direct tunnel and electrostatic couplings between them. We demonstrate their interaction, mediated by the cavity photons. This could be used to scale up quantum bit architectures based on quantum dot circuits or simulate on-chip phonon-mediated interactions between strongly correlated electrons.

  14. 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.

  15. Long coherence times in self-assembled semiconductor quantum dots

    DEFF Research Database (Denmark)

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

    2002-01-01

    We report measurements of ultra-long 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 mueV, 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. 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...... is obtained by exciting and detecting the photoluminescence through a microscope objective which is located inside the cryostat. Furthermore, e-beam lithography and mesa etching have been used to reduce the size of the detection area to a few hundred nanometers in diameter. These techniques allow us...

  17. Competitive Performance of Carbon “Quantum” Dots in Optical Bioimaging

    OpenAIRE

    Li Cao, Sheng-Tao Yang, Xin Wang, Pengju G. Luo, Jia-Hui Liu, Sushant Sahu, Yamin Liu, Ya-Ping Sun

    2012-01-01

    Carbon-based “quantum” dots or carbon dots are surface-functionalized small carbon nanoparticles. For bright fluorescence emissions, the carbon nanoparticles may be surface-doped with an inorganic salt and then the same organic functionalization. In this study, carbon dots without and with the ZnS doping were prepared, followed by gel-column fractionation to harvest dots of 40% and 60% in fluorescence quantum yields, respectively. These highly fluorescent carbon dots were evaluate...

  18. Competitive Performance of Carbon “Quantum” Dots in Optical Bioimaging

    OpenAIRE

    Cao, Li; Yang, Sheng-Tao; Wang, Xin; Luo, Pengju G.; Liu, Jia-Hui; Sahu, Sushant; Liu, Yamin; Sun, Ya-Ping

    2012-01-01

    Carbon-based “quantum” dots or carbon dots are surface-functionalized small carbon nanoparticles. For bright fluorescence emissions, the carbon nanoparticles may be surface-doped with an inorganic salt and then the same organic functionalization. In this study, carbon dots without and with the ZnS doping were prepared, followed by gel-column fractionation to harvest dots of 40% and 60% in fluorescence quantum yields, respectively. These highly fluorescent carbon dots were evaluated for optica...

  19. 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

  20. Semiconductor quantum dot-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Jianjun Tian

    2013-10-01

    Full Text Available Semiconductor quantum dots (QDs have been drawing great attention recently as a material for solar energy conversion due to their versatile optical and electrical properties. The QD-sensitized solar cell (QDSC is one of the burgeoning semiconductor QD solar cells that shows promising developments for the next generation of solar cells. This article focuses on recent developments in QDSCs, including 1 the effect of quantum confinement on QDSCs, 2 the multiple exciton generation (MEG of QDs, 3 fabrication methods of QDs, and 4 nanocrystalline photoelectrodes for solar cells. We also make suggestions for future research on QDSCs. Although the efficiency of QDSCs is still low, we think there will be major breakthroughs in developing QDSCs in the future.

  1. Excitonic physics in a Dirac quantum dot

    Science.gov (United States)

    Raca, V.; Milovanović, M. V.

    2017-11-01

    We present a description of vacuum polarization in a circular Dirac quantum dot in two spatial dimensions assuming α —the relative strength of the Coulomb interaction small enough to render an approximation with a single electron (hole) lowest energy level relevant. Applying this approximation, we find that for αc≈1.05 the lowest level is half filled irrespective of the number of flavors that are present. The ground state can be represented as a superposition of particular (even number) excitonic states which constitute an excitonic cloud that evolves in a crossover manner. The ground state is degenerate with an intervalley excitonic state at αc≈1.05 , a critical strength, that in our approximation marks a point with single electron and exciton resonances.

  2. Quantum-dot based photonic quantum networks

    Science.gov (United States)

    Lodahl, Peter

    2018-01-01

    Quantum dots (QDs) embedded in photonic nanostructures have in recent years proven to be a very powerful solid-state platform for quantum optics experiments. The combination of near-unity radiative coupling of a single QD to a photonic mode and the ability to eliminate decoherence processes imply that an unprecedent light–matter interface can be obtained. As a result, high-cooperativity photon-emitter quantum interfaces can be constructed opening a path-way to deterministic photonic quantum gates for quantum-information processing applications. In the present manuscript, I review current state-of-the-art on QD devices and their applications for quantum technology. The overarching long-term goal of the research field is to construct photonic quantum networks where remote entanglement can be distributed over long distances by photons.

  3. 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. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Tellurium quantum dots: Preparation and optical properties

    Science.gov (United States)

    Lu, Chaoyu; Li, Xueming; Tang, Libin; Lai, Sin Ki; Rogée, Lukas; Teng, Kar Seng; Qian, Fuli; Zhou, Liangliang; Lau, Shu Ping

    2017-08-01

    Herein, we report an effective and simple method for producing Tellurium Quantum dots (TeQDs), zero-dimensional nanomaterials with great prospects for biomedical applications. Their preparation is based on the ultrasonic exfoliation of Te powder dispersed in 1-methyl-2-pyrrolidone. Sonication causes the van der Waals forces between the structural hexagons of Te to break so that the relatively coarse powder breaks down into nanoscale particles. The TeQDs have an average size of about 4 nm. UV-Vis absorption spectra of the TeQDs showed an absorption peak at 288 nm. Photoluminescence excitation (PLE) and photoluminescence (PL) are used to study the optical properties of TeQDs. Both the PLE and PL peaks revealed a linear relationship against the emission and excitation energies, respectively. TeQDs have important potential applications in biological imaging and catalysis as well as optoelectronics.

  5. Electronic levels of cubic quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Aristone, Flavio [Federal De Mato Grosso Do Sul Univ., Campo Grande (Brazil); Sanchez-Dehesa, Jose [Autonoma De Madrid Univ., Madrid (Spain); Marques, Gilmar E. [Federal De Sao Carlos Univ., Sao Carlos (Brazil)

    2003-09-01

    We introduce an efficient variational method to solve the three-dimensional Schroedinger equation for any arbitrary potential V(x,y,z). The method uses a basis set of localized functions which are build up as products of one-dimensional cubic {beta}-splines. We calculated the energy levels of GaAs/AlGaAs cubic quantum dots and make a comparison with the results from two well-known simplification schemes based on a decomposition of the full potential problem into three separate one-dimensional problems. We show that the scheme making a sequential decomposition gives eigenvalues in better agreement with the ones obtained variationally, but an exact solution is necessary when looking for highly precise values.

  6. Biosensing with Luminescent Semiconductor Quantum Dots

    Directory of Open Access Journals (Sweden)

    Hedi Mattoussi

    2006-08-01

    Full Text Available Luminescent semiconductor nanocrystals or quantum dots (QDs are a recentlydeveloped class of nanomaterial whose unique photophysical properties are helping tocreate a new generation of robust fluorescent biosensors. QD properties of interest forbiosensing include high quantum yields, broad absorption spectra coupled to narrow sizetunablephotoluminescent emissions and exceptional resistance to both photobleaching andchemical degradation. In this review, we examine the progress in adapting QDs for severalpredominantly in vitro biosensing applications including use in immunoassays, asgeneralized probes, in nucleic acid detection and fluorescence resonance energy transfer(FRET - based sensing. We also describe several important considerations when workingwith QDs mainly centered on the choice of material(s and appropriate strategies forattaching biomolecules to the QDs.

  7. Semiconductor quantum dot-inorganic nanotube hybrids.

    Science.gov (United States)

    Kreizman, Ronen; Schwartz, Osip; Deutsch, Zvicka; Itzhakov, Stella; Zak, Alla; Cohen, Sidney R; Tenne, Reshef; Oron, Dan

    2012-03-28

    A synthetic route for preparation of inorganic WS(2) nanotube (INT)-colloidal semiconductor quantum dot (QD) hybrid structures is developed, and transient carrier dynamics on these hybrids are studied via transient photoluminescence spectroscopy utilizing several different types of QDs. Measurements reveal efficient resonant energy transfer from the QDs to the INT upon photoexcitation, provided that the QD emission is at a higher energy than the INT direct gap. Charge transfer in the hybrid system, characterized using QDs with band gaps below the INT direct gap, is found to be absent. This is attributed to the presence of an organic barrier layer due to the relatively long-chain organic ligands of the QDs under study. This system, analogous to carbon nanotube-QD hybrids, holds potential for a variety of applications, including photovoltaics, luminescence tagging and optoelectronics.

  8. Electron states in semiconductor quantum dots.

    Science.gov (United States)

    Dhayal, Suman S; Ramaniah, Lavanya M; Ruda, Harry E; Nair, Selvakumar V

    2014-11-28

    In this work, the electronic structures of quantum dots (QDs) of nine direct band gap semiconductor materials belonging to the group II-VI and III-V families are investigated, within the empirical tight-binding framework, in the effective bond orbital model. This methodology is shown to accurately describe these systems, yielding, at the same time, qualitative insights into their electronic properties. Various features of the bulk band structure such as band-gaps, band curvature, and band widths around symmetry points affect the quantum confinement of electrons and holes. These effects are identified and quantified. A comparison with experimental data yields good agreement with the calculations. These theoretical results would help quantify the optical response of QDs of these materials and provide useful input for applications.

  9. Recent advances in quantum dot surface chemistry.

    Science.gov (United States)

    Hines, Douglas A; Kamat, Prashant V

    2014-03-12

    Quantum dot (QD) surface chemistry is an emerging field in semiconductor nanocrystal related research. Along with size manipulation, the careful control of QD surface chemistry allows modulation of the optical properties of a QD suspension. Even a single molecule bound to the surface can introduce new functionalities. Herein, we summarize the recent advances in QD surface chemistry and the resulting effects on optical and electronic properties. Specifically, this review addresses three main issues: (i) how surface chemistry affects the optical properties of QDs, (ii) how it influences the excited state dynamics, and (iii) how one can manipulate surface chemistry to control the interactions between QDs and metal oxides, metal nanoparticles, and in self-assembled QD monolayers.

  10. Double quantum dots in carbon nanotubes

    Science.gov (United States)

    von Stecher, Javier; Wunsch, Bernhard; Lukin, Mikhail; Demler, Eugene; Rey, Ana Maria

    2010-03-01

    We study the behavior of few-electrons confined in a double-well quantum dot in semiconducting carbon nanotubes. These carbon nanostructures exhibit richer physics than GaAs ones due to the additional valley degree of freedom. We calculate and characterize the low energy eigenstates in the presence of a magnetic field and double-well detuning. Spin-orbit coupling lifts the spin and valley degeneracy and, in the presence of exchange interactions, leads, at small detunings and weak magnetic fields, to a spin-valley antisymmetric two-electron ground state which is not a pure spin-singlet state. At large detuning, the strong Coulomb interactions accessible in carbon nanotubes can substantially modify the non-interacting eigenstates via higher orbital-level mixing. The latter manifest in current transport experiments by the disappearance of the Pauli blockade.

  11. 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.

  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. 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

  14. 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.

  15. 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

  16. Electrical And Optical Properties Of Colloidal Quantum Dots And Quantum Dot Networks: Role Of Surface States And Using Biomolecular Links In Network Assembly

    National Research Council Canada - National Science Library

    Stroscio, Michael A; Dutta, Mitra; Ramadurai, Dinakar; Shi, Peng; Li, Yang; Alexson, Dimitri; Kohanpour, Babak; Sethuraman, Akil; Saini, Vikas; Raichura, Amit; Yang, Jianyong

    2004-01-01

    .... Absorption spectra and photoluminescence (PL) spectra of colloidal cadmium sulfide (CdS) quantum dots are analyzed to investigate the role of surface states in determining the electrical and optical properties of these semiconductor quantum dots...

  17. Enhanced Photoelectrochemical Response of Zn-Dotted Hematite

    Directory of Open Access Journals (Sweden)

    Saroj Kumari

    2007-01-01

    Full Text Available Photoelectrochemical response of thin films of α-Fe2O3, Zn doped α-Fe2O3, and Zn dots deposited on doped α-Fe2O3 prepared by spray pyrolysis has been studied. Samples of Zn dots were prepared using thermal evaporation method by evaporating Zn through a mesh having pore diameter of 0.7 mm. The presence of Zn-dotted islands on doped α-Fe2O3 surface exhibited significantly large photocurrent density as compared to other samples. An optimum thickness of Zn dots ∼230 Å is found to give enhanced photoresponse. The observed results are analyzed with the help of estimated values of resistivity, band gap, flatband potential, and donor density.

  18. 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...

  19. 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.

  20. WisDOT statewide customer satisfaction survey : [project brief].

    Science.gov (United States)

    2013-03-01

    The Wisconsin Department of Transportation (WisDOT) is a major public agency with numerous customers utilizing a variety of services and programs to support the entire statewide multimodal transportation system. The department also houses the Divisio...

  1. 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.

  2. 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.

  3. Quenched dynamics of entangled states in correlated quantum dots

    Science.gov (United States)

    Maslova, N. S.; Arseyev, P. I.; Mantsevich, V. N.

    2017-10-01

    The time evolution of an initially prepared entangled state in the system of coupled quantum dots has been analyzed by means of two different theoretical approaches: equations of motion for all orders localized electron correlation functions, considering interference effects, and kinetic equations for the pseudoparticle occupation numbers with constraint on the possible physical states. Results obtained by means of different approaches were carefully analyzed and compared to each other. Revealing a direct link between concurrence (degree of entanglement) and quantum dots pair correlation functions allowed us to follow the changes of entanglement during the time evolution of the coupled quantum dots system. It was demonstrated that the degree of entanglement can be controllably tuned during the time evolution of quantum dots system.

  4. 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.

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

    DEFF Research Database (Denmark)

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

    is coupled efficiently to a single enhanced mode. One popular approach has been to couple single quantum dots to a nanocavity but a limiting factor in this configuration is that in order to apply the photon it should subsequently be coupled out of the cavity, reducing the overall efficiency significantly....... 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......Efficient and high quality single-photon sources is a key element in quantum information processing using photons. As a consequence, much current research is focused on realizing all-solid-state nanophotonic single-photon sources. Single photons can be harvested with high efficiency if the emitter...

  6. Quantum Dots in the Therapy: Current Trends and Perspectives.

    Science.gov (United States)

    Pohanka, Miroslav

    2017-01-01

    Quantum dots are an emerging nanomaterial with broad use in technical disciplines; however, their application in the field of biomedicine becomes also relevant and significant possibilities have appeared since the discovery in 1980s. The current review is focused on the therapeutic applications of quantum dots which become an emerging use of the particles. They are introduced as potent carriers of drugs and as a material well suited for the diagnosis of disparate pathologies like visualization of cancer cells or pathogenic microorganisms. Quantum dots toxicity and modifications for the toxicity reduction are discussed here as well. Survey of actual papers and patents in the field of quantum dots use in the biomedicine is provided. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  7. 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...

  8. [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.

  9. Growth parameter optimization for fast quantum dot SESAMs.

    Science.gov (United States)

    Maas, D J H C; Bellancourt, A-R; Hoffmann, M; Rudin, B; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U

    2008-11-10

    Semiconductor saturable absorber mirrors (SESAMs) using quantum dot (QD) absorbers exhibit a larger design freedom than standard quantum well absorbers. The additional parameter of the dot density in combination with the field enhancement allows for an independent control of saturation fluence and modulation depth. We present the first detailed study of the effect of QD growth parameters and post growth annealing on the macroscopic optical SESAM parameters, measuring both nonlinear reflectivity and recombination dynamics. We studied a set of self-assembled InAs QD-SESAMs optimized for an operation wavelength around 960 nm with varying dot density and growth temperature. We confirm that the modulation depth is controlled by the dot density. We present design guidelines for QD-SESAMs with low saturation fluence and fast recovery, which are for example important for modelocking of vertical external cavity surface emitting lasers (VECSELs).

  10. Best Practices from WisDOT Mega and ARRA Projects

    Science.gov (United States)

    2012-03-01

    Since 2004 WisDOT has developed a number of new techniques, methods, processes and procedures for management of two new : types of transportation projects: Mega projects and projects funded through the American Recovery and Reinvestment Act of ...

  11. MnDOT research program strategic plan 2017-2022.

    Science.gov (United States)

    2017-03-01

    In response to the top transportation trends in Minnesota, and opportunities and challenges facing its transportation system, MnDOT has developed this five-year Research Program Strategic Plan (2017 2022) to take stock of its research portfolio, ...

  12. 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.

  13. Florida DOT Orlando ITS World Congress Vehicle Awareness Device

    Data.gov (United States)

    Department of Transportation — Florida DOT (FDOT) installed Vehicle Awareness Devices (VADs) on a set of Lynx transit buses as part of a demonstration for the ITS World Congress held in Orlando in...

  14. Dot-Projection Photogrammetry and Videogrammetry of Gossamer Space Structures

    Science.gov (United States)

    Pappa, Richard S.; Black, Jonathan T.; Blandino, Joseph R.; Jones, Thomas W.; Danehy, Paul M.; Dorrington, Adrian A.

    2003-01-01

    This paper documents the technique of using hundreds or thousands of projected dots of light as targets for photogrammetry and videogrammetry of gossamer space structures. Photogrammetry calculates the three-dimensional coordinates of each target on the structure, and videogrammetry tracks the coordinates versus time. Gossamer structures characteristically contain large areas of delicate, thin-film membranes. Examples include solar sails, large antennas, inflatable solar arrays, solar power concentrators and transmitters, sun shields, and planetary balloons and habitats. Using projected-dot targets avoids the unwanted mass, stiffness, and installation costs of traditional retroreflective adhesive targets. Four laboratory applications are covered that demonstrate the practical effectiveness of white-light dot projection for both static-shape and dynamic measurement of reflective and diffuse surfaces, respectively. Comparisons are made between dot-projection videogrammetry and traditional laser vibrometry for membrane vibration measurements. The paper closes by introducing a promising extension of existing techniques using a novel laser-induced fluorescence approach.

  15. 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.

  16. Coal as an abundant source of graphene quantum dots

    National Research Council Canada - National Science Library

    Ye, Ruquan; Xiang, Changsheng; Lin, Jian; Peng, Zhiwei; Huang, Kewei; Yan, Zheng; Cook, Nathan P; Samuel, Errol L G; Hwang, Chih-Chau; Ruan, Gedeng; Ceriotti, Gabriel; Raji, Abdul-Rahman O; Martí, Angel A; Tour, James M

    2013-01-01

    .... Here we report a facile approach to synthesize tunable graphene quantum dots from various types of coal, and establish that the unique coal structure has an advantage over pure sp2-carbon allotropes...

  17. Electro-absorption of silicene and bilayer graphene quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Abdelsalam, Hazem, E-mail: hazem.abdelsalam@etu.u-picardie.fr [Laboratory of Condensed Matter Physics, University of Picardie, Amiens 80039 (France); Department of Theoretical Physics, National Research Center, Cairo 12622 (Egypt); Talaat, Mohamed H. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Lukyanchuk, Igor [Laboratory of Condensed Matter Physics, University of Picardie, Amiens 80039 (France); L. D. Landau Institute for Theoretical Physics, Moscow (Russian Federation); Portnoi, M. E. [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Saroka, V. A., E-mail: v.saroka@exeter.ac.uk [School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk (Belarus)

    2016-07-07

    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.

  18. Open quantum dots in graphene: Scaling relativistic pointer states

    Energy Technology Data Exchange (ETDEWEB)

    Ferry, D K; Huang, L; Yang, R; Lai, Y-C; Akis, R, E-mail: ferry@asu.ed [School of Electrical, Computer, and Energy Engineering and Center for Solid State Electronics Research, Arizona State University, Tempe, AZ 85287-5706 (United States)

    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 'ashed 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.

  19. Graphene quantum dots as the electrolyte for solid state supercapacitors

    National Research Council Canada - National Science Library

    Zhang, Su; Li, Yutong; Song, Huaihe; Chen, Xiaohong; Zhou, Jisheng; Hong, Song; Huang, Minglu

    2016-01-01

    We propose that graphene quantum dots (GQDs) with a sufficient number of acidic oxygen-bearing functional groups such as -COOH and -OH can serve as solution- and solid- type electrolytes for supercapacitor...

  20. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M [Ithaca, NY; Edel, Joshua B [Brookline, MA; Samiee, Kevan T [Ithaca, NY; Craighead, Harold G [Ithaca, NY

    2008-07-29

    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.

  1. Electronic structure of double Ge quantum dots in Si

    Science.gov (United States)

    Yakimov, A. I.

    2012-09-01

    Theoretical investigations of the electronic structure of elastically stressed double Ge quantum dots in Si performed in the six-band kp approximation with the Bir-Pikus Hamiltonian and with the configuration interaction method are reviewed. The existence of the antibonding ground state of holes has been revealed. It has been found that, when quantum dots approach each other, the exchange energy of two-particle states has a minimum at the point of the intersection of bonding and antibonding levels; the singlet and triplet states at this point are degenerate. For the lowest spin singlet, it has been revealed that Coulomb correlations in the motion of two holes are manifested in the localization of the two-particle wavefunction at opposite quantum dots when the distance between the dots increases. It has been shown that the degree of entanglement of the singlet quantum states reaches 50% in the case of the manifestation of such spatial correlations.

  2. 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....

  3. Longitudinal modes of quantum dots in magnetic fields

    Science.gov (United States)

    Serra, Ll.; Pi, M.; Emperador, A.; Barranco, M.; Lipparini, E.

    The far infrared longitudinal spin and density responses of two-dimensional quantum dots are discussed within local spin-density functional theory. The influence of a partial spin polarization, induced by a perpendicular static magnetic field, is taken into account in the coupling of spin and density channels. As an illustrative application, the case of a dot made of 5 electrons in parabolic confinement is discussed.

  4. Noise and saturation properties of semiconductor quantum dot optical amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved.......We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved....

  5. 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....

  6. 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....

  7. Ultrafast optical properties of lithographically defined quantum dot amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Miaja-Avila, L.; Verma, V. B.; Mirin, R. P.; Silverman, K. L. [Quantum Electronics and Photonics Division, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Coleman, J. J. [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States)

    2014-02-10

    We measure the ultrafast optical response of lithographically defined quantum dot amplifiers at 40 K. Recovery of the gain mostly occurs in less than 1 picosecond, with some longer-term transients attributable to carrier heating. Recovery of the absorption proceeds on a much longer timescale, representative of relaxation between quantum dot levels and carrier recombination. We also measure transparency current-density in these devices.

  8. Quantum Dot Semiconductor Optical Amplifiers - Physics and Applications

    OpenAIRE

    Berg, Tommy Winther; Mørk, Jesper

    2004-01-01

    This thesis describes the physics and applications of quantum dot semiconductor optical amplifiers based on numerical simulations. These devices possess a number of unique properties compared with other types of semiconductor amplifiers, which should allow enhanced performance of semiconductor devices in communication systems in the future. The basic properties of quantum dot devices are investigated, especially regarding the potential of realizing amplification and signal processing without ...

  9. Localization in Artificial Disorder - Two Coupled Quantum Dots

    Science.gov (United States)

    Brodsky, Misha

    2000-03-01

    We study electron additions in 2D quantum dots of varying sizes and over a wide range of electron densities using Single Electron Capacitance Spectroscopy. For high electron densities in dots of any size, we observe a conventional pattern of nearly periodic Coulomb blockade. However, the addition spectra of electron droplets larger than 0.2 micron diameter and below a critical electron density (n_0=1x10^11cm-2 in all of our dots) are highly nonperiodic and contain pairs and bunches: two or more successive electrons can enter the dot at nearly the same energy; they show almost no sign of repelling each other. Application of high perpendicular magnetic field increases n_0, creating a sharp boundary between periodic and "paired" parts of the addition spectrum. Previously, we hypothesized that disorder and electron interactions within the low-density dot split it into two spatially separate droplets, and pairing arises once this localization occurs. Now we create a dot with a potential profile that contains two minima separated by a barrier. Our studies conclusively demonstrate that under precisely the same conditions for observation of the paired electron additions, a low-density electron droplet inside the dot indeed splits up into smaller fragments, each residing in a disorder minimum. We find that the two electrons added as a pair actually enter into spatially distinct regions within a dot, and we measure the remnant residual interaction between the fragments. Surprisingly, it displays nearly complete independence on the strength of the applied field for fields larger than required for the localization transition. While there exists no theory explaining the observed transition or the pairing phenomenon, recent numerical simulations display results similar to some of our data.cond- mat/9909220

  10. Gain recovery dynamics and limitations in quantum dot amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Bischoff, Svend; Magnúsdóttir, Ingibjörg

    2001-01-01

    gain recovery in a quantum dot amplifier, and it is thus not yet clear what the limiting processes for the device response are. We present the results of a comprehensive theoretical model, which agrees well with the experimental results, and indicates the importance of slow recovery of higher energy...... levels. The model used is of the rate-equation type with three energy levels: ground state (GS) and excited state (ES) dot levels and a wetting layer...

  11. High-Temperature Luminescence Quenching of Colloidal Quantum Dots

    OpenAIRE

    Zhao, Y.; Riemersma, C.; Pietra, F; de Mello Donega, C.; Meijerink, A.

    2012-01-01

    Thermal quenching of quantum dot (QD) luminescence is important for application in luminescent devices. Systematic studies of the quenching behavior above 300 K are, however, lacking. Here, high-temperature (300–500 K) luminescence studies are reported for highly efficient CdSe core–shell quantum dots (QDs), aimed at obtaining insight into temperature quenching of QD emission. Through thermal cycling (yoyo) experiments for QDs in polymer matrices, reversible and irreversible luminescence quen...

  12. Programmable Periodicity of Quantum Dot Arrays with DNA Origami Nanotubes

    OpenAIRE

    Bui, Hieu; Onodera, Craig; Kidwell, Carson; Tan, Yerpeng; Graugnard, Elton; Kuang, Wan; Lee, Jeunghoon; Knowlton, William B.; Yurke, Bernard; Hughes, William L.

    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 h...

  13. On the density of states of circular graphene quantum dots

    Science.gov (United States)

    Chau Nguyen, H.; Nguyen, Nhung T. T.; Nguyen, V. Lien

    2017-10-01

    We suggest a simple approach to calculate the local density of states that effectively applies to any structure created by an axially symmetric potential on a continuous graphene sheet such as circular graphene quantum dots or rings. Calculations performed for the graphene quantum dot studied in a recent scanning tunneling microscopy measurement (Gutierrez et al 2016 Nat. Phys. 12 1069-75) show an excellent experimental-theoretical agreement.

  14. Noncovalently silylated carbon nanotubes decorated with quantum dots

    OpenAIRE

    Bottini, Massimo; Magrini, Andrea; Dawson, Marcia I.; Rosato, Nicola; Bergamaschi, Antonio; Mustelin, Tomas

    2007-01-01

    A nanoassembly of single-walled carbon nanotubes coated by a thin layer of silica followed by quantum dots was prepared. That the quantum dots retained their photoluminescent properties after deposition onto the silylated carbon nanotubes suggests that the thin layer of silica prevented the quenching of the fluorescence by the nanotubes. This fluorescent nanoassembly represents an excellent building block for photoelectric and optical devices and biological nanoprobes.

  15. 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.

  16. Universal decay cascade model for dynamic quantum dot initialization

    OpenAIRE

    Kashcheyevs, Vyacheslavs; Kaestner, Bernd

    2009-01-01

    Dynamic quantum dots can be formed by time-dependent electrostatic potentials in nanoelectronic devices, such as gate- or surface-acoustic-wave-driven electron pumps. Ability to control the number of captured electrons with high precision is required for applications in fundamental metrology and quantum information processing. In this work we propose and quantify a scheme to initialize quantum dots with a controllable number of electrons. It is based on the stochastic decrease in the electron...

  17. Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications

    Science.gov (United States)

    Wen, Lin; Qiu, Liping; Wu, Yongxiang; Hu, Xiaoxiao; Zhang, Xiaobing

    2017-01-01

    Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided. PMID:28788080

  18. Magnetization reversal in circular vortex dots of small radius.

    Science.gov (United States)

    Goiriena-Goikoetxea, M; Guslienko, K Y; Rouco, M; Orue, I; Berganza, E; Jaafar, M; Asenjo, A; Fernández-Gubieda, M L; Fernández Barquín, L; García-Arribas, A

    2017-08-10

    We present a detailed study of the magnetic behavior of Permalloy (Ni80Fe20 alloy) circular nanodots with small radii (30 nm and 70 nm) and different thicknesses (30 nm or 50 nm). Despite the small size of the dots, the measured hysteresis loops manifestly display the features of classical vortex behavior with zero remanence and lobes at high magnetic fields. This is remarkable because the size of the magnetic vortex core is comparable to the dot diameter, as revealed by magnetic force microscopy and micromagnetic simulations. The dot ground states are close to the border of the vortex stability and, depending on the dot size, the magnetization distribution combines attributes of the typical vortex, single domain states or even presents features resembling magnetic skyrmions. An analytical model of the dot magnetization reversal, accounting for the large vortex core size, is developed to explain the observed behavior, providing a rather good agreement with the experimental results. The study extends the understanding of magnetic nanodots beyond the classical vortex concept (where the vortex core spins have a negligible influence on the magnetic behavior) and can therefore be useful for improving emerging spintronic applications, such as spin-torque nano-oscillators. It also delimits the feasibility of producing a well-defined vortex configuration in sub-100 nm dots, enabling the intracellular magneto-mechanical actuation for biomedical applications.

  19. Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications.

    Science.gov (United States)

    Wen, Lin; Qiu, Liping; Wu, Yongxiang; Hu, Xiaoxiao; Zhang, Xiaobing

    2017-07-28

    Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided.

  20. 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.