bluuebunny/crossref_metadata_2025 huggingface dataset:
Marcos de contestación y constitución urbana: la construcción de espacios de participación política en el concejo de Cuenca (siglo XV)
Authors: Jara Fuente José Antonio
Published: May 2012

Obéir ou désobéir, telle n’est pas la question. Face à l’essence de l’être, réduite à l’état binaire déclamé par Hamlet, le caractère accidentel de l’obéissance/ désobéissance admet une multiplicité de résultats en fonction des objectifs poursuivis par les acteurs sociaux et de la nature et forme des relations politiques qui les lient. Dans ce sens, la cité castillane, soumise au principe d’obéissance au roi, fut capable de produire tout un ensemble de catégories et de pratiques politiques moyennant lesquelles elle fut capable de s’introduire non seulement dans l’ample espace de construction politique qui s’étendait entre obéissance et désobéissance, mais aussi dans l’espace de défi nition et d’opérativité de l’obéissance elle-même. À travers l’étude du cas de la cité de Cuenca au XVe siècle, nous analyserons les modes de défi nition et d’opération de ce processus de négociation politique qui se trouve à la base du principe d’obéissance.
Afonso Henriques: do valor fundacional da desobediência
Authors: do Rosário Ferreira Maria
Published: May 2012

Le plus ancien récit en langue vernaculaire concernant le premier roi du Portugal, D. Afonso Henriques, a soulevé, au fil des temps, bien des perplexités concernant le héros qu’il dépeint et dont le manque d’exemplarité éthique n’est que trop évident. Il est dans notre propos de montrer que, à la lumière de la tradition narrative médiévale, le fondateur d’un royaume peut s’accommoder d’une personnalité ambiguë si toutefois ses fautes et sa capacité de les expier forment le ciment de la survie de la collectivité.
Obediencia y desobediencia en la literatura trovadoresca occitana medieval
Authors: Rossell Antoni
Published: May 2012

À partir d’une citation biblique de saint Paul et d’un article d’Aurelio Roncaglia sur un texte de Guillaume d’Aquitaine, l’obéissance dans les textes troubadouresques prend un caractère plus moral, éthique, et religieux qu’amoureux ou érotique. L’obéissance dans les textes masculins de la fin’amors revêt une intention culturelle et cognitive. Un aspect intéressant est la relation entre l’obéissance et la crainte, qui est incorporée dans une transgression religieuse. Toutefois, les textes féminins des trobairitz diffèrent des textes de troubadours en raison de leur dimension plus passionnelle et érotique.
L’obéissance ou la mise à l’épreuve chez Don Juan Manuel et Boccace
Authors: Garcia Michel
Published: May 2012

La obediencia de la esposa hacia su marido es un tema a menudo tratado en colecciones de cuentos y apólogos. Hemos elegido la historia de Griselda, última del Decamerón de Boccaccio. La comparamos primero con un texto castellano contemporáneo, el exemplum 27 del Conde Lucanor de Don Juan Manuel. Luego analizamos la revisión a la que la somete Petrarca al fi nal de su vida. Por fin, la situamos dentro de un contexto más amplio, en torno al Libro de Job, modelo siempre presente de una refl exión metafísica sobre la obediencia debida al Creador.
Le chevalier désobéissant dans la littérature arthurienne : modèle ou repoussoir ?
Authors: Laranjinha Ana Sofia
Published: May 2012

Le roman arthurien est un puissant champ de réflexion sur les rapports de pouvoir, étroits mais tendus, entre le roi et ses chevaliers. Dans Le Conte du Graal, le parcours de Perceval est fondé sur la désobéissance, mais il s’agit là d’un aspect de sa vitalité et de son excellence chevaleresque, qui l’oppose au courtois mais médiocre Gauvain, représentant de la cour arthurienne et de ses limites. Le neveu d’Arthur conserve son rôle et son caractère dans la première phase du cycle arthurien en prose, mais la naissance, dans la Suite du Merlin, du thème de la haine entre les lignages de Lot et Pellinor est à l’origine d’une métamorphose qui s’affirme dans la troisième phase de rédaction du Tristan en Prose et s’achève dans la Quête du Pseudo-Boron

(représentée par la Demanda portugaise), où le contraste entre un Gauvain courtois bien que malchanceux et un Gauvain félon découle d’une écriture en deux phases. Le discrédit dans lequel tombe la désobéissance s’explique par la hantise du désordre et de la fi n des temps qui marque la deuxième phase de rédaction de la Demanda.
Le marquis de Villena don Juan Pacheco (1419-1454), modèle de désobéissance seigneuriale, dans l’historiographie du règne d’Henri IV de Castille (1454-1474)
Authors: Carette Alice
Published: May 2012

Don Juan Pacheco fut le premier privado d’Henri IV de Castille, puis son ennemi le plus puissant. S’il soutint de nouveau le roi dans le confl it de succession contre Isabelle, le marquis de Villena, instigateur de la farsa de Ávila (1465), est néanmoins passé à la postérité comme une incarnation extrême de la désobéissance seigneuriale. Cet article montre comment l’historiographie du règne d’Henri IV, dans la continuité de la Segunda Partida d’Alphonse X, exprime la notion d’obéissance (obediençia) au roi, qui implique réciproquement, pour le souverain, le devoir de commander (mandar). Il analyse ensuite le discours des différents chroniqueurs, favorables au monarque ou non - Enríquez del Castillo et Pedro de Escavias ou Valera et Palencia, notamment - sur l’attitude de Pacheco envers le roi : désobéissance caractérisée pour les uns, duplicité pour les autres. Il montre enfin que, si tous déplorent l’inversion des fonctions de commandement et d’obéissance entre le privado et son monarque, ce constat est utilisé pour présenter Henri tantôt en tyran, tantôt en victime.
Apuntes para una historia lingüística del juramento en español medieval : el verbo jurar y otros verbos conexos
Authors: López Izquierdo Marta
Published: May 2012

Nous analysons dans ce travail l’expression du serment médiéval à travers l’étude des relations sémantiques, pragmatiques et discursives existant entre jurar, prometer et perjurar. Nous introduisons les notions de modulation, renfort et crédit pour rendre compte de la parenté entre les énoncés performatifs, assertifs et promissifs, considérés comme des actes de langage différents dans la théorie standard.
Spatial-symbolic Query Engine in Anatomy
Authors: Mejino J. L. V. , Detwiler L. T. , Franklin J. D. , Brinkley J. F. , Puget A.
Published: May 2012

Objectives: Currently, the primary means for answering anatomical questions such as ‘what vital organs would potentially be impacted by a bullet wound to the abdomen?’ is to look them up in textbooks or to browse online sources. In this work we describe a semantic web service and spatial query processor that permits a user to graphically pose such questions as joined queries over separately defined spatial and symbolic knowledge sources.

Methods: Spatial relations (e.g. anterior) were defined by two anatomy experts, and based on a 3-D volume of labeled images of the thorax, all the labeled anatomical structures were queried to retrieve the target structures for every query structure and every spatial relation. A web user interface and a web service were designed to relate existing symbolic information from the Foundational Model of Anatomy ontology (FMA) with spatial information provided by the spatial query processor, and to permit users to select anatomical structures and define queries.

Results: We evaluated the accuracy of results returned by the queries, and since there is no independent gold standard, we used two anatomy experts’ opinions as the gold standard for comparison. We asked the same experts to define the gold standard and to define the spatial relations. The F-measure for the overall evaluation is 0.90 for rater 1 and 0.56 for rater 2. The percentage of observed agreement is 99% and Cohen’s kappa coefficient reaches 0.51. The main source of disagreement relates to issues with the labels used in the dataset, and not with the tool itself.

Conclusions: In its current state the system can be used as an end-user application but it is likely to be of most use as a framework for building end-user applications such as displaying the results as a 3-D anatomical scene. The system promises potential practical utility for obtaining and navigating spatial and symbolic data.
Surgical Workflow Management Schemata for Cataract Procedures
Authors: Liebmann P. , Wiedemann P. , Meixensberger J. , Neumuth T.
Published: May 2012

Objective: Workflow guidance of surgical activities is a challenging task. Because of variations in patient properties and applied surgical techniques, surgical processes have a high variability. The objective of this study was the design and implementation of a surgical workflow management system (SWFMS) that can provide a robust guidance for surgical activities. We investigated how many surgical process models are needed to develop a SWFMS that can guide cataract surgeries robustly.

Methods: We used 100 cases of cataract surgeries and acquired patient-individual surgical process models (iSPMs) from them. Of these, randomized subsets iSPMs were selected as learning sets to create a generic surgical process model (gSPM). These gSPMs were mapped onto workflow nets as work-flow schemata to define the behavior of the SWFMS. Finally, 10 iSPMs from the disjoint set were simulated to validate the workflow schema for the surgical processes. The measurement was the successful guidance of an iSPM.

Results: We demonstrated that a SWFMS with a workflow schema that was generated from a subset of 10 iSPMs is sufficient to guide approximately 65% of all surgical processes in the total set, and that a subset of 50 iSPMs is sufficient to guide approx. 80% of all processes.

Conclusion: We designed a SWFMS that is able to guide surgical activities on a detailed level. The study demonstrated that the high inter-patient variability of surgical processes can be considered by our approach.
Polymorphic chloroplast microsatellite loci in Nelumbo (Nelumbonaceae)
Authors: Xue Jianhua , Wang Shuo , Zhou Shi‐Liang
Published: May 2012

• Premise of the study: To study population genetics, phylogeography, and hybridization of Nelumbo (Nelumbonaceae), chloroplast microsatellite markers were developed.

• Methods and Results: Seventeen microsatellite loci were identified from the chloroplast genomes of N. nucifera and N. lutea. Polymorphisms were assessed in three populations of N. nucifera and one population of N. lutea. Nine loci were found to be polymorphic in N. nucifera, and all 17 loci were found to be polymorphic in N. lutea. In N. nucifera, the number of alleles per locus ranged from two to six, and the unbiased haploid diversity per locus ranged from 0.198 to 0.790. In N. lutea, the number of alleles ranged from two to four, and the unbiased haploid diversity per locus ranged from 0.245 to 0.694.

• Conclusions: The identified chloroplast simple sequence repeat markers will be useful for the study of genetic diversity, phylogeography, and identification of Nelumbo cultivars.
Microsatellite primers for the endangered aquatic herb, Ottelia acuminata (Hydrocharitaceae)
Authors: Xu Chao , Du Zhi‐Yuan , Chen Jin‐Ming , Wang Qing‐Feng
Published: May 2012

• Premise of the study: Microsatellite primers were developed in the endangered aquatic herb, Ottelia acuminata, to characterize its genetic diversity and understand its population structure.

• Methods and Results: Eight polymorphic microsatellite markers were developed from two populations of O. acuminata in China. The number of alleles per locus ranged from one to 15; the observed and expected heterozygosities ranged from 0 to 0.885 and from 0 to 0.888, respectively, in the two populations. Selected loci also amplified successfully in O. sinensis.

• Conclusions: These microsatellite markers will facilitate further studies on the conservation genetics and evolutionary history of O. acuminata.
Les réseaux sur le marché du travail sud-africain
Authors: Ferrant Gaëlle
Published: May 2012

Résumé Les interactions sociales au sein des groupes ethniques peuvent expliquer les différences individuelles sur le marché du travail sud-africain : être entouré de pairs employés augmente la probabilité d’être employé et les salaires. Cet effet diffère par un effet de sélection : les femmes et les groupes ethniques discriminés sur le marché du travail bénéficient plus des effets de pairs. Les problèmes d’endogénéité et de simultanéité sont traités en utilisant les données agrégées au niveau de la province puis en instrumentant le réseau. L’importance des interactions sociales sur le marché du travail sud-africain indique qu’un multiplicateur social existe : tout choc serait amplifié avec une élasticité de 0,5.
Âge d'entrée à l'école, accumulation de capital humain et parcours scolaire
Authors: Fleury Nicolas
Published: May 2012

Résumé Cet article évalue économétriquement l’impact de l’âge d’entrée à l’école primaire sur l’accumulation individuelle de capital humain et les parcours scolaires pour le cas français. Nous exploitons l’expérience naturelle constituée de la variation du mois de naissance des individus et de la possibilité d’entrées tardives ou avancées à l’école, permettant de fortes variations de l’âge effectif d’entrée à l’école. Mobilisant l’enquête Formation et Qualification professionnelle, nous montrons que l’âge d’entrée n’a pas d’impact sur les indicateurs d’accumulation de capital humain (années d’éducation, niveau de diplôme), mais influence le parcours scolaire (indicateurs de redoublement ou de poursuite d’études techniques/professionnelles). Les estimations menées sur des échantillons séparés de femmes et d’hommes nuancent et précisent ces résultats.
Transferts de fonds des migrants en Afrique du Sud
Authors: Arestoff Florence , Kuhn Mélanie , Mouhoub El Mouhoud
Published: May 2012

Résumé Utllisant une enquête menée en 2006 auprès de 639 migrants africains présents à Johannesburg (Afrique du Sud), cet article analyse les déterminants des transferts de fonds dans le cas des migrations Sud-Sud. En plus des variables traditionnelles (revenu, âge, éducation du migrant, etc.), l’impact des conditions de départ du pays d’origine sur les transferts est analysé, ainsi que celui de variables subjectives (perception de richesse et attachement du migrant à son pays d’origine). Les résultats montrent qu’avoir fui son pays pour des raisons de violence réduit significativement la propension à transférer, tandis que l’attachement et la perception d’une situation économique meilleure dans le pays d’accueil favorisent les transferts.
Dimension temporelle et taux de change d'équilibre
Authors: López-Villavicencio Antonia , Mazier Jacques , Saadaoui Jamel
Published: May 2012

Résumé Dans un cadre théorique unifié introduit par López-Villavicencio et al. [2012], nous analysons les deux principaux modèles de taux de change d’équilibre, à savoir, le taux de change d’équilibre fondamental ( feer 1 ) et le taux de change d’équilibre comportemental ( beer 2 ). Afin de comprendre les interactions entre ces deux mesures, nous étudions en détail la dimension temporelle. Le cas des États-Unis illustrera notre analyse qui met en avant les changements structurels en matière de compétitivité, la dynamique des positions extérieures nettes et les effets de valorisation pour expliquer les divergences.
La volatilité des actions françaises sur le long terme
Authors: Le Bris David
Published: May 2012

Résumé La volatilité des actions françaises montre une forte instabilité depuis cent cinquante ans. Très faible avant la Première Guerre mondiale, elle augmente de façon continue durant l’entre-deux-guerres. Malgré la paix et la stabilité économique, la volatilité n’a jamais retrouvé ses niveaux d’avant 1914. Le niveau de la volatilité des actions semble lié à l’instabilité monétaire et à l’ampleur du déficit public.
Une évaluation économique du risque de modèle pour les investisseurs de long terme
Authors: Boucher Christophe , Hamidi Benjamin , Kouontchou Patrick , Maillet Bertrand
Published: May 2012

Résumé Les récents épisodes de turbulence financière sont venus remettre en cause la précision des mesures classiques de risque pour évaluer les risques extrêmes. Ces mesures de risques, telles que la v a r , sont devenues incontournables dans la gestion des risques et l’allocation d’actifs (Basak et Shapiro [2001] ; Monfort [2008]). Nous estimons le risque de modèle des mesures de risque et nous évaluons son impact sur l’allocation d’actifs optimale à différents horizons. Nos résultats montrent, sur des données longues américaines, une relation en U inversé entre notre mesure du risque de modèle sur les v a r historiques et l’horizon de l’agent représentatif, qui impacte sensiblement son allocation optimale.
Le coup médiatique
Authors: Champagne Patrick
Published: May 2012

Résumé Contre les approches réalistes et nominalistes , qui ont en commun d’oublier que ce n’est pas à l’analyste de dire ce qu’est et ce que n’est pas un événement, cet article s’attache à montrer que la définition de l’événement est précisément l’enjeu d’une lutte, et que c’est cette lutte qu’il importe de prendre pour objet. Le travail scientifique en la matière consiste alors à prendre en compte l’ensemble des acteurs sociaux qui sont en lutte pour imposer une certaine idée de ce qu’est censé être un événement. En l’occurrence, la notion d’événement est devenue fortement dépendante de l’industrie des médias ; elle est inhérente au fonctionnement même des salles de rédaction au point qu’on ne sait plus très bien si la presse « met en une » les événements qui existent indépendamment des journalistes ou si c’est le fait d’être mis en une qui contribue à faire ce qu’on appelle un événement. Les journalistes en effet ne sont pas de simples intermédiaires se bornant à diffuser et à commenter des événements qui existeraient en soi, en dehors d’eux, et qui seraient aisément saisissables. Ils ont leur propre conception de l’événement qui n’est pas celle de l’historien, de l’homme politique ou du citoyen ordinaire. Ils sont de plus soumis à la pression de ceux qui, parce qu’ils estiment que c’est leur intérêt, veulent que l’on parle d’eux dans les médias, et tentent, avec l’aide de conseillers en communication, de « faire événement ». Cela signifie qu’un journaliste, ou même un journal, ne peuvent pas décider à eux seuls de ce qui doit être considéré comme un « événement » : chacun, dans le champ journalistique, y contribue seulement à la mesure de la position qu’il occupe dans cet espace. Analysant de près comment ont été « faits » plusieurs événements médiatiques récents (campagne contre l’insécurité routière de 2003, l’affaire du RER D en 2004, notamment), cette étude démontre ainsi combien l’événement est le fait d’une construction collective qu’il faut rendre à ses logiques sociales.
Jack D. Ives y la geoecología de las áreas de montaña
Authors: González-Trueba J. J. , García-Ruiz J. M.
Published: May 2012

Se hace una breve presentación de la obra de Jack D. Ives, uno de los grandes protagonistas del desarrollo de los estudios de Geoecología en las áreas de montaña. Con sus trabajos en ambientes fríos y de montaña (Montañas Rocosas e Himalaya, especialmente), Jack D. Ives ha proporcionado una nueva perspectiva global en la que la forma en que se organizan los grupos humanos y sus actividades son factores decisivos para explicar la complejidad de los ambientes de montaña.
El origen de la geoecología de las áreas de montaña
Authors: Ives Jack D.
Published: May 2012

La geoecología de montaña, como sub-disciplina de la Geografía, entronca con la vida y trabajo de Carl Troll, quien, a su vez, fue inspirado por la filosofía y viajes de Alexander von Humboldt. Como presidente fundador de la comisión de la UGI sobre High Altitude Geoecology (1968), Troll colocó las bases para la investigación interdisciplinar e internacional de las montañas. Este trabajo presenta la evolución de la Comisión y sus estrechas relaciones con el Programa Hombre y Biosfera de UNESCO (1972-) y con el Proyecto de montaña de la Universidad de Naciones Unidas (1978-). Esto facilitó la inclusión de un capítulo sobre la montaña en AGENDA 21 durante la Cumbre de la Tierra de Río de Janeiro (UNCED), y la consiguiente designación de 2002 como el Año Internacional de las Montañas por parte de Naciones Unidas. En este sentido, la geoecología de montaña no sólo contribuyó a la investigación de las montañas del mundo sino que también empujó a la política en el esfuerzo por un desarrollo sostenible de la montaña y el bienestar de los habitantes de la montaña.
¿Puede la disponibilidad temporal de datos determinar el calentamiento percibido por las tribus nómadas de mongoles cerca de las montañas Khangai?
Authors: Venable N. B. H. , Fassnacht S. R. , Adyabadam G. , Tumenjargal S. , Fernández-Giménez M. , Batbuyan B.
Published: May 2012

Los cambios de temperatura pueden ser difíciles de inferir a partir de los cambios en los patrones de vegetación u otros cambios ecológicos. Sin embargo, el calentamiento se puede inferir a través de cambios en los hábitos de las personas que viven en estrecha relación con su entorno natural. Los pastores de las montañas de Mongolia central, cerca deKhangai, perciben una tendencia hacia el calentamiento en los últimos años. Ya que resulta difícil determinar el período de tiempo exacto durante el que se ha producido el calentamiento, se analizó la diferencia estadística de los cambios en función de la longitud de los datos y el período de registros utilizado en el análisis. Hemos utilizado los datos de temperatura de cinco estaciones meteorológicas con 50 años de registros (1961-2010). Se examinaron diferentes longitudes de registro (de 15 a 50 años) con períodos de inicio diferentes (1961 a 1986). Se comprobó que los cambios estadísticamente más significativos se registran en los períodos más largos y considerando las temperaturas mínimas medias anuales. También se encontró que un invierno muy frío, en particular (2009-2010) disminuyó la tendencia al calentamiento.
Tendencias recientes e índices de cambio climático de la temperatura y la precipitación en Andorra, Pirineos (1935-2008)
Authors: Esteban Vea P. , Prohom Duran M. , Aguilar E.
Published: May 2012

En este trabajo se muestran los resultados obtenidos del cálculo de las tendencias anuales y estacionales de la temperatura máxima, temperatura mínima y la precipitación en el Principado de Andorra (Pirineos) a partir del análisis de tres series climáticas situadas entre los 1140 y los 1645 m. Los cálculos de tendencia se han obtenido para el periodo 1935-2008 correspondiente a la longitud total de la series, así como para el sub-periodo 1950-2008. A partir de las mismas series a resolución diaria se han calculado los índices de cambio climático definidos por el ETCCDMI (Expert Teamfor Climate Change Detection Monitoring and Indices).
Los resultados confirman las tendencias detectadas regionalmente por otros organismos, tanto franceses como españoles. Así, se confirma el incremento significativo de la temperatura del aire para la temperatura máxima media anual (0.13 a 0.15 ºC / década), para la máxima estival (0,22 ºC / década), y la mínima estival (0.11 ºC / década). Dichas tendencias al incremento térmico se refuerzan cuando el análisis se centra en el sub-periodo 1950-2008. En cuanto a la precipitación, se obtienen tendencias decrecientes y estadísticamente significativas para el periodo 1935-2008 en la estación de Central y en verano (-5.4 %/década), mientras que este comportamiento se generaliza y refuerza si nos ceñimos al periodo 1950-2008.
Finalmente, los resultados del cálculo de los índices diarios del ETCCDMI confirman y detallan lo ya obtenido a más baja resolución. Así, los índices computados a partir de las series de temperatura indican un claro incremento de extremos asociados a días cálidos y un descenso de sus opuestos. En cuanto a los índices de precipitación, no se detecta ninguno con tendencia significativa para el periodo 1935-2008, mientras que varios de ellos sí que presentan valores decrecientes con significación estadística para el sub-periodo 1950-2008.
Observaciones del cambio ambiental del pastoralismo pirenaico: un estudio exploratorio en los Valles Occidentales de Aragón
Authors: Fernández-Giménez María E. , Fillat Federico
Published: May 2012

Las observaciones sobre el cambio medioambiental realizadas por usuarios locales pueden ser una importante fuente de información sobre las características medioambientales del pasado y del presente para complementar los estudios científicos y el monitoreo. En este estudio cualitativo documentamos observaciones sobre el cambio medioambiental realizadas por 27 ganaderos en los dos valles más occidentales de los Pirineos centro occidentales españoles. Resumen cambios climáticos relativos a la disminución del caudal de las fuentes de montaña y al aumento de la cubierta vegetal de matorrales y arbolado en las montañas. Las explicaciones sobre el aumento de arbolado difieren en los dos valles; sin embargo la mayoría de los ganaderos de ambos pueblos pensaban que la falta de presencia humana en las montañas contribuye a la invasión del matorral. Las observaciones de los ganaderos sobre los cambios medioambientales sugieren la necesidad de investigaciones adicionales sobre los cambios climáticos y de vegetación en los Pirineos y evidencian las potenciales contribuciones del conocimiento local de los ganaderos para el monitoreo medioambiental, la investigación y la gestión.
Corrosión a temperatura alta del acero ferrítico 9Cr-1Mo modificado P91, en atmósferas simuladas oxidantes-carburantes
Authors: Peña-Ballesteros D. Y. , Vásquez-Quintero C. , Laverde-Cataño D. , Serna G A.
Published: May 2012

La corrosión a temperatura alta en unidades de transformación de la industria química, petroquímica, carboquímica y termoeléctrica es de alto interés, debido a los costos generados por fallas repentinas causadas por el deterioro en las propiedades mecánicas de los metales, siendo la carburación de la matriz metálica el mecanismo de corrosión más importante produciendo pérdida de ductilidad y resistencia a la termofluencia. En esta investigación un acero 9Cr-1Mo modificado P91 se expuso a atmósferas simuladas oxidantes-carburantes simultáneas de mezclas gaseosas en equilibrio de CO, CO2, CH4, H2O y H2, similares a las producidas en los equipos de la industria de refinación, a temperaturas entre 550 y 750 oC. Se analizó la evolución microestructural de la matriz metálica, también el crecimiento, evolución y el comportamiento de capas de óxidos y carburadas, estableciéndose el mecanismo de deterioro del material y la extensión de daño para tiempos superiores a 700 h de exposición.
Loss of TNF Signaling Facilitates the Development of a Novel Ly-6Clow Macrophage Population Permissive for Leishmania major Infection
Authors: Fromm Phillip D. , Kling Jessica , Mack Matthias , Sedgwick Jonathon D. , Körner Heinrich
Published: May 2012

In the absence of TNF, the normally resistant C57BL/6 (B6.WT) strain develops a fatal, progressive form of leishmaniasis after infection with Leishmania major. It is not yet understood which TNF activity or the lack thereof is responsible for the dramatic progression of leishmaniasis in TNF-negative (B6.TNF−/−) mice. To elucidate the underlying mechanisms resulting in the fatal outcome of L. major infection in this gene-deficient mouse strain, we analyzed the monocytic component of the inflammatory infiltrate in the draining popliteal lymph node and the site of the infection using multicolor flow cytometry. The leukocytic infiltrate within the draining lymph node and footpad of B6.TNF−/− mice resembled that of B6.WT mice over the first 2 wk of cutaneous L. major infection. Thereafter, the B6.TNF−/− mice showed an increase of CD11c+Ly-6C+CCR2+ monocytic dendritic cells within the popliteal lymph node in comparison with B6.WT mice. This increase of inflammatory dendritic cells was paired with the accumulation of a novel CD11b+Ly-6ClowCCR2low population that was not present in B6.WT mice. This B6.TNF−/−- and B6.TNFR1−/−-specific cell population was CD115+Ly-6G−iNOS−, not apoptotic, and harbored large numbers of parasites.
Dimerization of NKp46 Receptor Is Essential for NKp46-Mediated Lysis: Characterization of the Dimerization Site by Epitope Mapping
Authors: Jaron-Mendelson Michal , Yossef Rami , Appel Michael Y. , Zilka Alon , Hadad Uzi , Afergan Fabian , Rosental Benyamin , Engel Stanislav , Nedvetzki Shlomo , Braiman Alex , Porgador Angel
Published: May 2012

NKp46 is a primary activating receptor of NK cells that is involved in lysis of target cells by NK cells. Previous studies showed that the membrane-proximal domain of NKp46 (NKp46D2) retained the binding of NKp46 to its ligands and is involved in lysis. We studied NKp46D2 by using a peptide-based epitope mapping approach and identified an NKp46D2-derived linear epitope that inhibited NKp46-mediated lysis. The epitope, designated as pep4 (aa 136–155), interacted with NKp46, and lysis by NK cells was inhibited by the presence of pep4. Through modeling and mutagenesis, we showed that pep4 could be involved in NKp46 homodimerization. R145 and D147 contribute to the function of pep4, and R145Q mutation in recombinant NKp46 reduced its binding to target cells. At the cellular level, fluorescent resonance energy transfer analysis revealed that pep4 is indeed involved in dimerization of cell membrane-associated NKp46. We suggest that the NKp46-derived pep4 site is part of the dimerization surface of NKp46 and that NKp46 dimerization contributes to NKp46-mediated lysis by NK cells.
Human CCR4+CCR6+Th17 Cells Suppress Autologous CD8+ T Cell Responses
Authors: Zhao Fei , Hoechst Bastian , Gamrekelashvili Jaba , Ormandy Lars A. , Voigtländer Torsten , Wedemeyer Heiner , Ylaya Kris , Wang Xin Wei , Hewitt Stephen M. , Manns Michael P. , Korangy Firouzeh , Greten Tim F.
Published: May 2012

The role of Th17 cells in cancer patients remains unclear and controversial. In this study, we have analyzed the phenotype of in vitro primed Th17 cells and further characterized their function on the basis of CCR4 and CCR6 expression. We show a novel function for a subset of IL-17–secreting CD4+ T cells, namely, CCR4+CCR6+Th17 cells. When cultured together, CCR4+CCR6+Th17 cells suppressed the lytic function, proliferation, and cytokine secretion of both Ag-specific and CD3/CD28/CD2-stimulated autologous CD8+ T cells. In contrast, CCR4−CCR6+ CD4+ T cells, which also secrete IL-17, did not affect the CD8+ T cells. Suppression of CD8+ T cells by CCR4+CCR6+Th17 cells was partially dependent on TGF-β, because neutralization of TGF-β in cocultures reversed their suppressor function. In addition, we also found an increase in the frequency of CCR4+CCR6+, but not CCR4−CCR6+ Th17 cells in peripheral blood of hepatocellular carcinoma patients. Our study not only underlies the importance of analysis of subsets within Th17 cells to understand their function, but also suggests Th17 cells as yet another immune evasion mechanism in hepatocellular carcinoma. This has important implications when studying the mechanisms of carcinogenesis, as well as designing effective immunotherapy protocols for patients with cancer.
Dendritic Cell-Specific Transcript: Dendritic Cell Marker and Regulator of TLR-Induced Cytokine Production
Authors: Hontelez Saartje , Ansems Marleen , Karthaus Nina , Zuidscherwoude Malou , Looman Maaike W. , Triantis Vassilis , Adema Gosse J.
Published: May 2012

Dendritic cells (DCs) are the professional APCs of the immune system that dictate the type and course of an immune response. Molecular understanding of DC biology is important for the design of DC-based immunotherapies and optimal clinical applications in vaccination settings. Previously, we isolated and characterized the cDNA-encoding dendritic cell-specific transcript (DC-SCRIPT; also known as ZNF366). DC-SCRIPT mRNA expression in the immune system was confined to DCs and was reported to be an early hallmark of DC differentiation. In this study, we demonstrate IL-4 to be the dominant factor for DC-SCRIPT expression in human monocyte-derived DCs. In addition, to our knowledge, we show for the first time endogenous DC-SCRIPT protein expression in human DCs both in vitro and in situ. DC-SCRIPT protein is detected early upon differentiation of monocytes into DCs and is also present in multiple freshly isolated DC subsets. Maturation of DCs with TLR ligands further increased DC-SCRIPT mRNA expression, suggesting a role in DC maturation. Indeed, small interfering RNA-mediated knockdown of DC-SCRIPT affected the cytokine response upon TLR stimulation. These DCs displayed enhanced IL-10 and decreased IL-12 production, compared with wild-type DCs. Silencing of IL-10 in DC-SCRIPT knockdown DCs rescued IL-12 expression, suggesting a primary role for DC-SCRIPT in the regulation of IL-10 production.
Glucocorticoids Relieve Collectin-Driven Suppression of Apoptotic Cell Uptake in Murine Alveolar Macrophages through Downregulation of SIRPα
Authors: McCubbrey Alexandra L. , Sonstein Joanne , Ames Theresa M. , Freeman Christine M. , Curtis Jeffrey L.
Published: May 2012

The lung environment actively inhibits apoptotic cell (AC) uptake by alveolar macrophages (AMøs) via lung collectin signaling through signal regulatory protein α (SIRPα). Even brief glucocorticoid (GC) treatment during maturation of human blood monocyte-derived or murine bone marrow-derived macrophages (Møs) increases their AC uptake. Whether GCs similarly impact differentiated tissue Møs and the mechanisms for this rapid response are unknown and important to define, given the widespread therapeutic use of inhaled GCs. We found that the GC fluticasone rapidly and dose-dependently increased AC uptake by murine AMøs without a requirement for protein synthesis. Fluticasone rapidly suppressed AMø expression of SIRPα mRNA and surface protein, and also activated a more delayed, translation-dependent upregulation of AC recognition receptors that was not required for the early increase in AC uptake. Consistent with a role for SIRPα suppression in rapid GC action, murine peritoneal Møs that had not been exposed to lung collectins showed delayed, but not rapid, increase in AC uptake. However, pretreatment of peritoneal Møs with the lung collectin surfactant protein D inhibited AC uptake, and fluticasone treatment rapidly reversed this inhibition. Thus, GCs act not only by upregulating AC recognition receptors during Mø maturation but also via a novel rapid downregulation of SIRPα expression by differentiated tissue Møs. Release of AMøs from inhibition of AC uptake by lung collectins may, in part, explain the beneficial role of inhaled GCs in inflammatory lung diseases, especially emphysema, in which there is both increased lung parenchymal cell apoptosis and defective AC uptake by AMøs.
Evaluation of central nervous system depressant activity of Cleome rutidosperma
Authors: Bose Anindya , Khuntia Anuradha , Gupta Jayanta Kumar , Si Sudam
Published: May 2012

The central nervous system (CNS) depressant activity of the ethanol extract (200 and 400 mg/kg) and its fractions (200 mg/kg each) of the aerial parts of Cleome rutidosperma was investigated in various models. The tested extract and its fractions showed significant (P<0.01) anxiolytic, anticonvulsant activity (in treating petit mal epilepsy) without any unwanted sedation effect. These findings justify the traditional use of this plant in CNS disorders.
Hematological Profile of Sickle Cell Disease from South Gujarat, India
Authors: Rao Sanjeev Shyam , Goyal Jagdish Prasad , Raghunath S. V. , Shah Vijay
Published: May 2012

The aim of this study was to determine hematological profile of sickle cell disease (SCD) from Surat, South Gujarat, India. This prospective cross-sectional study was conducted in the Department of Pediatrics and Sickle Cell Anemia Laboratory, Faculty of Pathology, Government Medical College, Surat, India, between July 2009 and December 2010. Patients included in this study were in their steady state for a long period of time without any symptoms related to SCD or other diseases which could affect the hematological parameters. Venous blood of all patients was collected in ethylenediaminetetraacetic acid and hematological indices were measured. Thirty-three subjects homozygous in all were studied for their hematological parameters for sickle cell anemia. Moderate to severe anemia, low mean cell volume and high foetal hemoglobin dominate the hematological profile of SCD children.
Pseudostress-Based Mixed Finite Element Methods for the Stokes Problem in ℝnwith Dirichlet Boundary Conditions. I: A Priori Error Analysis
Authors: Gatica Gabriel N. , Márquez Antonio , Sánchez Manuel A.
Published: May 2012

We consider a non-standard mixed method for the Stokes problem in ℝn,nЄ {2,3}, with Dirichlet boundary conditions, in which, after using the incompressibility condition to eliminate the pressure, the pseudostress tensor σ and the velocity vectorubecome the only unknowns. Then, we apply the Babuška-Brezzi theory to prove the well-posedness of the corresponding continuous and discrete formulations. In particular, we show that Raviart-Thomas elements of orderk≥0 for σ and piecewise polynomials of degreekforuensure unique solvability and stability of the associated Galerkin scheme. In addition, we introduce and analyze an augmented approach for our pseudostress-velocity formulation. The methodology employed is based on the introduction of the Galerkin least-squares type terms arising from the constitutive and equilibrium equations, and the Dirichlet boundary condition for the velocity, all of them multiplied by suitable stabilization parameters. We show that these parameters can be chosen so that the resulting augmented variational formulation is defined by a strongly coercive bilinear form, whence the associated Galerkin scheme becomes well posed for any choice of finite element subspaces. For instance, Raviart-Thomas elements of orderk≥0 for σ and continuous piecewise polynomials of degreek+1 forubecome a feasible choice in this case. Finally, extensive numerical experiments illustrating the good performance of the methods and comparing them with other procedures available in the literature, are provided.
A Cluster Dynamics Model For Accumulation Of Helium In Tungsten Under Helium Ions And Neutron Irradiation
Authors: Li Y. G. , Zhou W. H. , Ning R. H. , Huang L. F. , Zeng Z. , Ju X.
Published: May 2012

A cluster dynamics model based on rate theory has been developed to describe the accumulation and diffusion processes of helium in tungsten under helium implantation alone or synergistic irradiation with neutron, by involving different types of objects, adopting up-to-date parameters and complex reaction processes as well as considering the diffusion process along with depth. The calculated results under different conditions are in good agreement with experiments much well. The model describes the behavior of helium in tungsten within 2D space of defect type/size and depth on different ions incident conditions (energies and fluences) and material conditions (system temperature and existent sinks), by including the synergistic effect of helium-neutron irradiations and the influence of inherent sinks (dislocation lines and grain boundaries). The model, coded as IRadMat, would be universally applicable to the evolution of defects for ions/neutron irradiated on plasma-facing materials.
Elements of Mathematical Foundations for Numerical Approaches for Weakly Random Homogenization Problems
Authors: Anantharaman A. , Le Bris C.
Published: May 2012

This work is a follow-up to our previous work. It extends and complements, both theoretically and experimentally, the results presented there. Under consideration is the homogenization of a model of a weakly random heterogeneous material. The material consists of a reference periodic material randomly perturbed by another periodic material, so that its homogenized behavior is close to that of the reference material. We consider laws for the random perturbations more general than in. We prove the validity of an asymptotic expansion in a certain class of settings. We also extend the formal approach introduced in. Our perturbative approach shares common features with a defect-type theory of solid state physics. The computational efficiency of the approach is demonstrated.
Improvement on Spherical Symmetry in Two-Dimensional Cylindrical Coordinates for a Class of Control Volume Lagrangian Schemes
Authors: Cheng Juan , Shu Chi-Wang
Published: May 2012

In, Maire developed a class of cell-centered Lagrangian schemes for solving Euler equations of compressible gas dynamics in cylindrical coordinates. These schemes use a node-based discretization of the numerical fluxes. The control volume version has several distinguished properties, including the conservation of mass, momentum and total energy and compatibility with the geometric conservation law (GCL). However it also has a limitation in that it cannot preserve spherical symmetry for one-dimensional spherical flow. An alternative is also given to use the first order area-weighted approach which can ensure spherical symmetry, at the price of sacrificing conservation of momentum. In this paper, we apply the methodology proposed in our recent work to the first order control volume scheme of Maire in to obtain the spherical symmetry property. The modified scheme can preserve one-dimensional spherical symmetry in a two-dimensional cylindrical geometry when computed on an equal-angle-zoned initial grid, and meanwhile it maintains its original good properties such as conservation and GCL. Several two-dimensional numerical examples in cylindrical coordinates are presented to demonstrate the good performance of the scheme in terms of symmetry, non-oscillation and robustness properties.
A Unstructured Nodal Spectral-Element Method for the Navier-Stokes Equations
Authors: Chen Lizhen , Shen Jie , Xu Chuanju
Published: May 2012

An unstructured nodal spectral-element method for the Navier-Stokes equations is developed in this paper. The method is based on a triangular and tetrahedral rational approximation and an easy-to-implement nodal basis which fully enjoys the tensorial product property. It allows arbitrary triangular and tetrahedral mesh, affording greater flexibility in handling complex domains while maintaining all essential features of the usual spectral-element method. The details of the implementation and some numerical examples are provided to validate the efficiency and flexibility of the proposed method.
Numerical Simulation of a Three-Dimensional Fish-like Body Swimming with Finlets
Authors: Wang Shizhao , Zhang Xing , He Guowei
Published: May 2012

The swimming of a 3D fish-like body with finlets is numerically investigated at Re = 1000 (the Reynolds number is based on the uniform upstream flow and the length of the fish-like body). The finlets are simply modeled as thin rigid rectangular plates that undulate with the body. The wake structures and the flow around the caudal peduncle are studied. The finlets redirect the local flow across the caudal peduncle but the vortical structures in the wake are almost not affected by the finlets. Improvement of hydrodynamic performance has not been found in the simulation based on this simple model. The present numerical result is in agreement with that of the work of Nauen and Lauder [J. Exp. Biol., 204 (2001), pp. 2251-2263] and partially supports the hypothesis of Webb [Bull. Fish. Res. Bd. Can., 190 (1975), pp. 1-159].
Effects of Dzyaloshinsky-Moriya Interaction on Planar Rotator Model on Triangular Lattice
Authors: Sun Yun-Zhou , Yi Lin , Wang Jian-Sheng
Published: May 2012

The thermodynamic properties and some critical properties of the planar rotator model with chiral Dzyaloshinsky-Moriya (DM) interaction on triangular lattice are analyzed using a hybrid Monte Carlo method. It has been shown that there is a XY-like Berezinskii-Kosterlitz-Thouless (BKT) phase transition in this model. The ground state of this spiral system and the effects of size mismatch are also discussed.
Lattice Free Stochastic Dynamics
Authors: Sopasakis Alexandros
Published: May 2012

We introduce a lattice-free hard sphere exclusion stochastic process. The resulting stochastic rates are distance based instead of cell based. The corresponding Markov chain build for this many particle system is updated using an adaptation of the kinetic Monte Carlo method. It becomes quickly apparent that due to the lattice-free environment, and because of that alone, the dynamics behave differently than those in the lattice-based environment. This difference becomes increasingly larger with respect to particle densities/temperatures. The well-known packing problem and its solution (Palasti conjecture) seem to validate the resulting lattice-free dynamics.
Parareal in Time Simulation Of Morphological Transformation in Cubic Alloys with Spatially Dependent Composition
Authors: He Li-Ping , He Minxin
Published: May 2012

In this paper, a reduced morphological transformation model with spatially dependent composition and elastic modulus is considered. The parareal in time al-gorithm introduced by Lions et al. is developed for longer-time simulation. The fine solver is based on a second-order scheme in reciprocal space, and the coarse solver is based on a multi-model backward Euler scheme, which is fast and less expensive. Numerical simulations concerning the composition with a random noise and a discontinuous curve are performed. Some microstructure characteristics at very low temperature are obtained by a variable temperature technique.
Supersonic Flows with Nontraditional Transport Described by Kinetic Methods
Authors: Aristov V. V. , Frolova A. A. , Zabelok S. A.
Published: May 2012

A new class of supersonic nonequilibrium flows is studied on the basis of solving the Boltzmann and model kinetic equations with the aim to consider new non-linear structures in open systems and to study anomalous transfer properties in relaxation zones. The Unified Flow Solver is applied for numerical simulations. Simple gases and gases with inner degrees of freedom are considered. The experimental data related to the influence of the so-called optical lattices on the supersonic molecular beams are considered and numerical analysis of the nonequilibrium states obtained on this basis is made. The nonuniform relaxation problem with these distributions is simulated numerically and anomalous transport is confirmed. The conditions for strong changes of the temperature in the anomalous transfer zones are discussed and are realized in computations.
Analysis And Efficient Solution Of Stationary Schrödinger Equation Governing Electronic States Of Quantum Dots And Rings In Magnetic Field
Authors: Betcke Marta M. , Voss Heinrich
Published: May 2012

In this work the one-band effective Hamiltonian governing the electronic states of a quantum dot/ring in a homogenous magnetic field is used to derive a pair/quadruple of nonlinear eigenvalue problems corresponding to different spin orientations and in case of rotational symmetry additionally to quantum number -L•i. We show, that each of those pair/quadruple of nonlinear problems allows for the min-max characterization of its eigenvalues under certain conditions, which are satisfied for our examples and the common InAs/GaAs heterojunction. Exploiting the minmax property we devise efficient iterative projection methods simultaneously handling the pair/quadruple of nonlinear problems and thereby saving up to 40% of the computational time as compared to the nonlinear Arnoldi method applied to each of the problems separately.
A Well-Posed and Discretely Stable Perfectly Matched Layer for Elastic Wave Equations in Second Order Formulation
Authors: Duru Kenneth , Kreiss Gunilla
Published: May 2012

We present a well-posed and discretely stable perfectly matched layer for the anisotropic (and isotropic) elastic wave equations without first re-writing the governing equations as a first order system. The new model is derived by the complex coordinate stretching technique. Using standard perturbation methods we show that complex frequency shift together with a chosen real scaling factor ensures the decay of eigen-modes for all relevant frequencies. To buttress the stability properties and the robustness of the proposed model, numerical experiments are presented for anisotropic elastic wave equations. The model is approximated with a stable node-centered finite difference scheme that is second order accurate both in time and space.