930 resultados para Abelhas sem ferrão


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BACKGROUND: The magnitude of risk conferred by the interaction between tobacco and alcohol use on the risk of head and neck cancers is not clear because studies have used various methods to quantify the excess head and neck cancer burden. METHODS: We analyzed individual-level pooled data from 17 European and American case-control studies (11,221 cases and 16,168 controls) participating in the International Head and Neck Cancer Epidemiology consortium. We estimated the multiplicative interaction parameter (psi) and population attributable risks (PAR). RESULTS: A greater than multiplicative joint effect between ever tobacco and alcohol use was observed for head and neck cancer risk (psi = 2.15; 95% confidence interval, 1.53-3.04). The PAR for tobacco or alcohol was 72% (95% confidence interval, 61-79%) for head and neck cancer, of which 4% was due to alcohol alone, 33% was due to tobacco alone, and 35% was due to tobacco and alcohol combined. The total PAR differed by subsite (64% for oral cavity cancer, 72% for pharyngeal cancer, 89% for laryngeal cancer), by sex (74% for men, 57% for women), by age (33% for cases <45 years, 73% for cases >60 years), and by region (84% in Europe, 51% in North America, 83% in Latin America). CONCLUSIONS: Our results confirm that the joint effect between tobacco and alcohol use is greater than multiplicative on head and neck cancer risk. However, a substantial proportion of head and neck cancers cannot be attributed to tobacco or alcohol use, particularly for oral cavity cancer and for head and neck cancer among women and among young-onset cases.

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Mittakaavaa ei määritelty.

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On y remarque : Factums pour et contre Philippe de Buisine, docteur régent et doyen de la Faculté de décret, impr. (fol. 3, 11, etc.) ; — Discours de Philippe DE BUISINE, 1656, etc., in-4°, impr. (fol. 26, 29, 40) ; — « Franciscus DE ROYE, antecessor Andegavensis, ad capit. super specula 28 de privil. et excess. privil. apud Greg., ubi Apologeticus pro omnibus Galliarum antecessoribus, contra Parisienses canonici juris professores », Angers, Pierre Avril, 1665, in-4° de 58 pages, impr. (fol. 56) ; — « Pro omnibus Franciae antecessoribus praescriptio adversus canonistas Parisienses... », Bourges, Jean Toubeau, 1665, in-4° de 36 pages, impr. (fol. 118) ; — « Protrepticum ad Regem et omnes per Europam principes de usu et necessitate juris civilis Romanorum et ejus in integrum restituendi rationibus sive in Academiis sive in Tribunalibus », Bourges, Jean Toubeau, 1666, in-4° de 13 pages, impr. (fol. 136) ; — Copie d'un acte de Louis XIV, 1655 (fol. 158) ; — « Statuta Facultatis medicinae Parisiensis, 1660 », in-16 de 104 pages, impr. (fol. 164) ; — Factums et autres pièces imprimées concernant François Blondel, docteur régent en la Faculté de médecine, 1666 (fol. 217, etc.), — notamment : « Francisci BLONDELI, doctoris medici Parisiensis, ad clarissimum virum Petrum Alliot, Barroducaeum, ducis a Lotharingia consiliarium et medicum ordinarium, epistola de nuntio profligati sine ferro et igne carcinomatis, ducibus itineris Hippocrate et Galeno, nunc nuper ab eodem misso ad chirurgiae studiosos », 1666, in-4° de 38 pages, impr. (fol. 231) ; — « Antonii MENJOTII, consiliarii et medici regii, epistola apologetica de variis sectis amplectendis, ejusdemque epistolae adversus Hadriani Scauri ineptias defensio », 1666, in-4° de 32 pages, impr. (fol. 287) ; — Suite d'épigrammes et autres pièces de vers, en latin, concernant principalement des médecins, in-4°, impr. (fol. 303) ; — « ALETHOPHANIS archiatri ad Jacobum Thevartum, ex-medicum Parisiensem et R. M., hoc est reum manifestarium violati sacramenti nec non corruptae artis, epistola..., Eleutheris, typis notoriis, anno 1655 », in-4° de 35 pages, impr. (fol. 317) ; — « Lettre écrite à Monsieur Oldenburg, gentilhomme anglois et secrétaire de l'Académie royalle d'Angleterre, par Jean DENIS, docteur en médecine et professeur ez mathématiques, touchant les différens qui sont arrivez à l'occasion de la transfusion du sang », 1668, in-4° de 12 pages, impr. (fol. 336) ; — « Statuta honorandae nationis gallicanae », in-4° de 27 pages, impr. (fol. 345) ; — « Demande des docteurs de Sorbonne aux héritiers du cardinal de Richelieu, tant pour achever les bastimens de l'église et du collège, que pour l'entretien desdicts bastimens, à quoy a esté accordé 60.000 livres pour l'entretien des bastimens » (fol. 359) ; — « Fondatio et statuta Collegii et capellanie Cenomanensis pro pauperibus dioeceseos Cenomanicae, ut studeant in alma Universitate Parisiensi et secundum decreta ipsius vitam degant », in-8° de 45 pages, impr. (fol. 371) ; — « Contrat entre R. P. Charles de Beaumanoir, évesque du Mans, et les Jésuites du Collège de Clermont, par lequel une chapelle et un collège fondé par l'éminentissime cardinal de Luxembourg, pour entretenir des pauvres boursiers en l'Université de Paris, sont vendus et achetez à prix d'argent » [1625], in-8° de 24 pages (fol. 395) ; — « De statu Andegavensis Academiae Papirii MASSONI rectoris oratio... », 1571, in-8° de 16 pages non chiffrées, impr. (fol. 407) ; — « Sorbona instaurata, seu illustrissimo cardinali D. Joanni Armando de Richelieu, provisori Sorbonae, actio gratiarum Joannis FILESACI, doctoris theologi sorbonici », 1629, in-4° de 35 pages, impr. (fol. 415), — et « Gratulatio illustrissimi cardinalis », 1629, in-4° de 3 pages, impr. (fol. 432) ; — « Déclaration du Roy, portant establissement d'une Académie et Collège royal en la ville de Richelieu et les privilèges attribuez à icelle, ensemble les statuts et règlemens de ladite Académie », 1641, in-4° de 22 pages, impr. (fol. 435), — et copie manuscrite (fol. 679) ; — « La Fondation du Collège Mazarini » [1661], in-4° de 16 pages, impr. (fol. 447) ; — « Concordat fait entre MM. les exécuteurs de la fondation du Collège... Mazarini, et les religieux de la Congrégation de saint Maur, pour l'union de l'abbaye de S. Michel en l'Herm », Paris, Antoine Vitré, 1669, in-4° de 15 pages, impr. (fol. 455) ; — Pièces concernant le Collège d'Harcourt : Factum in-4°, impr. (fol. 463), — et « Statuta venerabilis Collegii Harcuriani », statuts de 1311, s. l. n. d., in-4° de 16 pages, impr. (fol. 503) ; — Pièces sur les « petites écoles », notamment : Acte orig. de Louis XIV, 6 mai 1675 (fol. 513), — et « Mémoires justificatifs des conclusions de l'Université sur le fait des petites escoles » (fol. 515) ; — Censure de l'Historia Universitatis Parisiensis de Du Boulay : « Excerpta ex opere M. Caesaris Egasse cognomento Bullaei, aliàs du Boulay, quod inscribitur : Historia Universitatis Parisiensis, contra fidem et sacram doctrinam », s. d., in-folio de 53 pages, impr. (fol. 526), — et « Notae ad censuram editam nomine Facultatis theologiae in opus quod inscribitur : Historia Universitatis Parisiensis » [1667], in-4° de 12 pages, impr. (fol. 552) ; — Copie d'un acte de Philippe VI de Valois, « certa gratia facta scolaribus Universitatis Aurelianensis », 1337 (fol. 581) ; — « Johannis ROBERTI, antecessorum Aurelianensium ordinis decani et consiliarii regii, de Aurelianensi juris utriusque schola instauranda oratio... », Orléans, Olivier Boynard, 1582, in-4° de 16 feuillets, impr. (fol. 586) ; — « Francisci GALTERI, Parisini, pro Academia oratio, habita pridie idus januarii, in aula Harcuriana... », 1597, in-16 de 42 pages, impr. (fol. 606) ; — Pièces concernant les messagers de l'Université (fol. 632, etc.) ; — Requête de l'Université contre les Jésuites (fol. 641) ; — « Mémoire pour l'establissement de quatre chaires de professeurs de théologie en l'Université d'Angers » (fol. 657).

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Gestión del conocimiento

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This thesis describes two different approaches for the preparation of polynuclear clusters with interesting structural, magnetic and optical properties. Firstly, exploiting p-tert-butylcalix[4]arene (TBC4) macrocycles together with selected Ln(III) ions for the assembly of emissive single molecule magnets, and secondly the preparation and coordination of a chiral mpmH ligand with selected 3d transition metal ions, working towards the discovery of chiral polynuclear clusters. In Project 1, the coordination chemistry of the TBC4 macrocycle together with Dy(III) and Tb(III) afforded two Ln6[TBC4]2 complexes that have been structurally, magnetically and optically characterized. X-ray diffraction studies reveal that both complexes contain an octahedral core of Ln6 ions capped by two fully deprotonated TBC4 macrocycles. Although the unit cells of the two complexes are very similar, the coordination geometries of their Ln(III) ions are subtly different. Variable temperature ac magnetic susceptibility studies reveal that both complexes display single molecule magnet (SMM) behaviour in zero dc field and the energy barriers and associated pre-exponential factors for each relaxation process have been determined. Low temperature solid state photoluminescence studies reveal that both complexes are emissive; however, the f-f transitions within the Dy6 complex were masked by broad emissions from the TBC4 ligand. In contrast, the Tb(III) complex displayed green emission with the spectrum comprising four sharp bands corresponding to 5D4 → 7FJ transitions (where J = 3, 4, 5 and 6), highlighting that energy transfer from the TBC4 macrocycle to the Tb(III) ion is more effective than to Dy. Examples of zero field Tb(III) SMMs are scarce in the chemical literature and the Tb6[TBC4]2 complex represents the first example of a Tb(III) dual property SMM assembled from a p-tert-butylcalix[4]arene macrocycle with two magnetically derived energy barriers, Ueff of 79 and 63 K. In Project 2, the coordination of both enantiomers of the chiral ligand, α-methyl-2-pyridinemethanol (mpmH) to Ni(II) and Co(II) afforded three polynuclear clusters that have been structurally and magnetically characterized. The first complex, a Ni4 cluster of stoichiometry [Ni4(O2CCMe3)4(mpm)4]·H2O crystallizes in a distorted cubane topology that is well known in Ni(II) cluster chemistry. The final two Co(II) complexes crystallize as a linear mixed valence trimer with stoichiometry [Co3(mpm)6]·(ClO4)2, and a Co4 mixed valence complex [Co(II)¬2Co(III)2(NO3)2(μ-mpm)4(ONO2)2], whose structural topology resembles that of a defective double cubane. All three complexes crystallize in chiral space groups and circular dichroism experiments further confirm that the chirality of the ligand has been transferred to the respective coordination complex. Magnetic susceptibility studies reveal that for all three complexes, there are competing ferro- and antiferromagnetic exchange interactions. The [Co(II)¬2Co(III)2(NO3)2(μ-mpm)4(ONO2)2] complex represents the first example of a chiral mixed valence Co4 cluster with a defective double cubane topology.

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The present work is an attempt to understand the characteristics of high energy ball milling on the structural, electrical and magnetic properties of some normal spinets in the ultra fine regime, Magnetism and magnetic materials have been a fascinating subject for the mankind ever since the discovery of lodestone. Since then, man has been applying this principle of magnetism to build devices for various applications. Magnetism can be classified broadly into five categories. They are diamagnetic, paramagnetic, ferromagnetic antiferromagnetic and ferrimagnetic. Of these, ferro and ferri magnetic materials assume great commercial importance due to their unique properties like appropriate magnetic characteristics, high resistivity and low eddy current losses. The emergence of nanoscience and nanotechnology during the last decade had its impact in the field of magnetism and magnetic materials too. Now, it is common knowledge that materials synthesized in the nanoregime exhibit novel and superlative properties with respect to their coarser sized counterparts in the micron regime. These studies reveal that dielectric properties can be varied appreciably by high-energy ball milling in nanosized zinc ferrites produced by coprecipitation method. A semi conducting behaviour was observed in these materials with the Oxygen vacancies acting as the main charge carrier for conduction, which was produced at the time of coprecipitation and milling. Thus through this study, it was possible to successfully investigate the finite size effects on the structural, electrical and magnetic properties of normal spinels in the ultra fine regime

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Research on transition-metal nanoalloy clusters composed of a few atoms is fascinating by their unusual properties due to the interplay among the structure, chemical order and magnetism. Such nanoalloy clusters, can be used to construct nanometer devices for technological applications by manipulating their remarkable magnetic, chemical and optical properties. Determining the nanoscopic features exhibited by the magnetic alloy clusters signifies the need for a systematic global and local exploration of their potential-energy surface in order to identify all the relevant energetically low-lying magnetic isomers. In this thesis the sampling of the potential-energy surface has been performed by employing the state-of-the-art spin-polarized density-functional theory in combination with graph theory and the basin-hopping global optimization techniques. This combination is vital for a quantitative analysis of the quantum mechanical energetics. The first approach, i.e., spin-polarized density-functional theory together with the graph theory method, is applied to study the Fe$_m$Rh$_n$ and Co$_m$Pd$_n$ clusters having $N = m+n \leq 8$ atoms. We carried out a thorough and systematic sampling of the potential-energy surface by taking into account all possible initial cluster topologies, all different distributions of the two kinds of atoms within the cluster, the entire concentration range between the pure limits, and different initial magnetic configurations such as ferro- and anti-ferromagnetic coupling. The remarkable magnetic properties shown by FeRh and CoPd nanoclusters are attributed to the extremely reduced coordination number together with the charge transfer from 3$d$ to 4$d$ elements. The second approach, i.e., spin-polarized density-functional theory together with the basin-hopping method is applied to study the small Fe$_6$, Fe$_3$Rh$_3$ and Rh$_6$ and the larger Fe$_{13}$, Fe$_6$Rh$_7$ and Rh$_{13}$ clusters as illustrative benchmark systems. This method is able to identify the true ground-state structures of Fe$_6$ and Fe$_3$Rh$_3$ which were not obtained by using the first approach. However, both approaches predict a similar cluster for the ground-state of Rh$_6$. Moreover, the computational time taken by this approach is found to be significantly lower than the first approach. The ground-state structure of Fe$_{13}$ cluster is found to be an icosahedral structure, whereas Rh$_{13}$ and Fe$_6$Rh$_7$ isomers relax into cage-like and layered-like structures, respectively. All the clusters display a remarkable variety of structural and magnetic behaviors. It is observed that the isomers having similar shape with small distortion with respect to each other can exhibit quite different magnetic moments. This has been interpreted as a probable artifact of spin-rotational symmetry breaking introduced by the spin-polarized GGA. The possibility of combining the spin-polarized density-functional theory with some other global optimization techniques such as minima-hopping method could be the next step in this direction. This combination is expected to be an ideal sampling approach having the advantage of avoiding efficiently the search over irrelevant regions of the potential energy surface.

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Resumen basado en el de la publicación

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L’ús de colorants alimentaris pot ser controvertit, ja que la seva presència s’associa amb problemes provocats pel seu consum a llarg termini, o perquè es tem que siguin emprats per dissimular deficiències en la qualitat del producte. Aquesta preocupació és una tendència creixent entre els consumidors i ha portat a moltes empreses del sector alimentari a revisar la formulació dels seus productes i substituir, sempre que sigui econòmica i tecnològicament possible, els colorants artificials per colorants naturals. L’hemoglobina procedent de la sang dels escorxadors industrials podria ser una font important de colorant vermell natural degut a les grans quantitats generades diàriament. A més, s' evitaria que anés a parar a les aigües residuals. El seu ús com a colorant vermell natural queda supeditada al fet de trobar alguna substància o sistema capaç de protegir-la de l’oxidació durant el procés de deshidratació i el posterior període d’emmagatzematge ja que l’hemoglobina és poc estable i es poden produir canvis en el seu color. Inicialment l’hemoglobina presenta un color vermell brillant. La seva desoxigenació comporta un canvi a color porpra. I l’oxidació del ferro confereix a la molècula un indesitjable color marró. En l’estudi que aquí es presenta es pretén estabilitzar el color de l’hemoglobina de sang porcina tant durant la seva deshidratació per atomització com durant l’emmagatzematge a temperatura ambient de la pols obtinguda afegint al concentrat d’hemoglobina, prèviament a la deshidratació, combinacions de diferents substàncies que puguin actuar de manera complementària en l’estabilització del ferro hèmic enfront la seva oxidació. L’objectiu d’aquest treball és determinar si la seva combinació amb agents antioxidants comporta una millora en l’estabilització de la forma reduïda de l’hemoglobina tant durant la deshidratació per atomització com durant l’emmagatzematge de la pols a temperatura ambient

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Con el objetivo de realizar un acercamiento preciso al tema migratorio y de Derechos Humanos y de comprender de manera global la complejidad y variables que intervienen, esta investigación estudiará el caso de Argentina y Bolivia en el periodo de 1997 y 2008, tiempo durante el cual surge la cooperación de actores tanto internos como externos que le dan importancia al control de fenómenos migratorios. Igualmente, se analizará la forma en la que el problema migratorio incide en la violación de los Derechos Humanos, como segunda variable, demostrando que es un problema que afecta las relaciones bilaterales.

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La seguridad siempre ha sido uno de los temas más importantes en la política internacional. Por ello, este trabajo pretende explicar algunos aspectos que han llevado al establecimiento del Mando militar de las fuerzas armadas de los Estados Unidos (AFRICOM) conforme a determinados intereses en materia de seguridad de Estados Unidos en África. Así, puntualiza el proceso de creación del AFRICOM, muestra los antecedentes históricos que marcaron su instauración, establece cuáles son los intereses, en materia de seguridad, de Estados Unidos en África, y el control de las amenazas a partir de la creación del AFRICOM y por último, analiza las reacciones que suscitó la creación del Comando. Ello, con el fin de determinar cuáles son las percepciones y críticas al respecto. Esto incluye, el análisis de un último interés de seguridad de Estados Unidos en África, la seguridad energética.

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El propósito central, se basa en el análisis de factibilidad de la implantación de un clúster de papa, a razón de los estudios realizados que indican la importancia del producto para la región al constituirse como el principal cultivo dentro del sector agrícola. No obstante, la participación del producto se sitúa en las últimas posiciones dentro de la Provincia de Almeidas, reflejando la débil gestión de los recursos necesarios para el cultivo. Finalmente, se propone la aplicación de la Metodología del Marco Lógico para esquematizar de manera precisa las acciones que podrían estimular la importancia de este proyecto, en aras de un desarrollo sistémico regional.

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Comunicando saberes es una propuesta de formación en artes y cultura que se articula en una región específica del País: el Departamento del Guaviare. A partir de la apropiación de “campos de expresiones y de conocimientos”, es decir, saberes colectivos y vigentes de los diferentes pueblos y regiones representados en este Departamento, se propone su reedificación (la creación), y su tránsito al plano de las significaciones colectivas (la comunicación). En esta propuesta formativa, el acto pedagógico no sólo deberá coincidir, suscitar y adaptarse a los procesos creativos conducidos o espontáneos que supone la actividad artística, sino que deberá poner en marcha otras estrategias tendientes a movilizar los conocimientos que luego se llevarán al acto formativo, a ampliar y mejorar la producción creativa, y activar las relaciones y el tránsito de las creaciones a la sociedad.