997 resultados para Drama, Radio, American.
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A health consultation is a verbal or written response from ATSDR or ATSDR’s Cooperative Agreement Partners to a specific request for information about health risks related to a specific site, a chemical release, or the presence of hazardous material. In order to prevent or mitigate exposures, a consultation may lead to specific actions, such as restricting use of or replacing water supplies; intensifying environmental sampling; restricting site access; or removing the contaminated material. In addition, consultations may recommend additional public health actions, such as conducting health surveillance activities to evaluate exposure or trends in adverse health outcomes; conducting biological indicators of exposure studies to assess exposure; and providing health education for health care providers and community members. This concludes the health consultation process for this site, unless additional information is obtained by ATSDR or ATSDR’s Cooperative Agreement Partner which, in the Agency’s opinion, indicates a need to revise or append the conclusions previously issued.
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Abstract The Northwestern edge of the modern Caribbean Plate, located in central Middle America (S-Guatemala to N-Costa Rica), is characterized by a puzzle of oceanic and continental terranes that belonged originally to the Pacific façade of North America. South of the Motagua Fault Zone, the actual northern strike slip boundary of the Caribbean Plate, three continental slivers (Copán, Chortis s. str. and Patuca) are sandwiched between two complex suture zones that contain HP/LT mafic and ultramafic oceanic rocks: The Motagua Mélanges to the North, extensively studied in the last ten years and the' newly defined Mesquito Composite Oceanic Terrane (MCOT) to the South. No modem geological data were available for the oceanic terrane located in the southern part of the so called continental "Chortis Block". Classically, the southern limit of this block with the Caribbean Large Igneous Province (CLIP) was placed at a hypothetical fault line connecting the main E-W fault in the Santa Elena Peninsula (N-Costa Rica) with the Hess Escarpment. However, our study in eastern Nicaragua and northwestern Costa Rica evidences an extensive assemblage of oceanic upper mantle and crustal rocks outcropping between the Chortis/Patuca continental blocks and the CLIP. They comprise collided and accreted exotic terranes of Pacific origin recording a polyphased tectonic history. We distinguish: 1- The MCOT that comprises a Late Triassic to Early Cretaceous puzzle of oceanic crust and arc-derived rocks set in a serpentinite matrix, and 2- The Manzanillo and Nicoya Terranes that are made of Cretaceous plateau-like rocks associated with oceanic sediments older than the CLIP. This study has been focused on the rocks of the MCOT. The MCOT comprises the southern half of the former "Chortis Block" and is defined by 4 comer localities characterized by ultramafic and mafic oceanic rocks of Late Triassic, Jurassic and Early Cretaceous age: 1- The Siuna Serpentinite Mélange (NE-Nicaragua), 2- The El Castillo Mélange (Nicaragua/Costa Rica border), 3- DSDP Legs 67 and 84 (Guatemala fore-arc basin), and 4- The Santa Elena Peridiotite (NW-Costa Rica). The Siuna Serpentinite Mélange (SSM) is a HP/LT subduction zone mélange set in a serpentinite matrix that contains oceanic crust and arc-related greenschist to blueschist/eclogite facies metamafic and metasedimentary blocks. Middle Jurassic (Bajocian-Bathonian) radiolarites are found in original sedimentary contact with arc-derived greenstones. Late Jurassic black detrital chert possibly formed in a marginal (fore-arc?) basin shortly before subduction. A phengite 40Ar/39Ar -cooling age dates the exhumation of the high pressure rocks as 139 Ma. The El Castillo Mélange (ECM) is composed of serpentinite matrix with OIB metabasalts and Late Triassic (Rhaetian) red and green radiolarite blocks. Recent studies of the DSDP Legs 67/84 show that the Guatemala/Nicaragua fore-arc basin is composed of a pile of ultramafic, mafic (OIB-like) and arc related rocks with ages ranging from Late Triassic to Campanian. Finally, the Santa Elena peridiotites that mark the limit of the MCOT with the Manzanillo/Nicoya Terranes and correspond to an association of ultramafic rocks that comprise peridiotites, dunites and chromites of abyssal and fore-arc origin. The SSM is the result of a collision between a Middle Jurassic island arc and the Patuca Terrane, a fragment of the Western N-American active continental margin. The Siuna Mélange (SSM) and the South Montagna Mélange share common characteristics with the Pacific N-American suture zone (E-Franciscan and Vizcaino mélanges), in particular, the Mesozoic ages of HP/LT metamorphic and the arc-derived blocks. For us, these mélanges imply an originally continuous, but slightly diachronous suture that affected the entire W-American active margin. It may imply the arrival and collision of an exotic intraoceanic arc (Guerrero-Phoenix) related to the origin of the Pacific Plate that initiated as a back arc basin of this arc. The present disposition of the fragments of this suture zone is the result of a northward shift of the active left-lateral strike slip motion between the N-American and the Caribbean Plates. Résumé Le coin nord-ouest de la Plaque Caraïbe moderne se trouve en Amérique Centrale, entre le sud du Guatemala et le nord du Costa Rica. Cette région est composée d'un puzzle de terrains océaniques et continentaux dont les origines se situent sur la façade pacifique de l'Amérique du Nord. Au sud de la faille de Motagua, la limite septentrionale actuelle, décrochante, de la Plaque Caraïbe, se trouvent 3 copeaux continentaux (Copàn, Chortis s. str. et Patuca) coincés entre deux zones de suture complexes à roches mafiques et ultramafiques qui ont subi un métamorphisme de haute pression/basse température (HP/LT). Il s'agit des Mélanges de Motagua au nord, largement étudiés ces dernières années, et du Mesquito Composite Oceanic Terrane (MCOT), récemment défini par nous, au sud. En vue de l'absence de données géologiques modernes concernant les terrains océaniques qui se trouvent dans la partie sud du "Chortis Block" considérée comme continentale, nous avons dédié cette étude à cette région. Classiquement, la limite méridionale entre le "Chortis Block" et la "Caribbean Large Igneous Province" (CLIP) a été associée à une faille hypothétique reliant la faille E-W de Santa Elena (nord du Costa Rica) à l'Escarpement de Hess. Notre étude au Nicaragua oriental et au Costa Rica nord-occidental a révélé l'existence de larges terrains composés d'assemblages de roches mantéliques et océaniques qui se placent entre les blocs continentaux Chortis/Patuca et le CLIP. Ces assemblages révèlent des terrains collisionnés et accrétés d'origine pacifique enregistrant une histoire tectonique polyphasée. Nous distinguons: 1- Le MCOT, un puzzle de roches océaniques d'arc d'âge Triassique supérieur au Crétacée inférieur, 2- Les terrains de Manzanillo et de Nicoya, des morceaux de plateaux océaniques associés à des sédiments océaniques plus âgés que le CLIP. Cette étude se focalisera sur les roches du MCOT. Le MCOT occupe la moitié sud de l'ancien "Chortis Block" et peut se définir par 4 localités de référence qui montrent des roches mafiques et ultramafiques océaniques d'âges compris entre le Trias supérieur et le Crétacée inférieur. 1- Le Siuna Serpentinite Mélange (NE-Nicaragua), 2- Le El Castillo Mélange (Nicaragua/Costa Rica border), 3- Le DSDP Legs 67/84 (Guatemala fore-arc basin) et 4- La Santa Elena Peridiotite (nord-ouest du Costa Rica). Le Siuna Serpentinite Mélange (SSM) est un mélange de subduction HP/BT dans une matrice de serpentinite. On y trouve des éléments de croûte océanique et d'arc insulaire en faciès de schistes verts et schistes bleus. Des radiolarites du Jurassique moyen se trouvent en contact sédimentaire sur des roches vertes d'arc. En revanche, des cherts noirs détritiques datent du Jurassique supérieur et sont probablement issus d'un bassin marginal (fore-arc ?) peu avant leur subduction, car un âge 40Ar/39Ar de refroidissement des phengites date l'exhumation des roches de haute pression à 139 Ma. Le Mélange d'El Castillo (ECM) est constitué d'une matrice serpentinitique et contient des blocs de metabasaltes OIB et des blocs de radiolarites du Trias terminal. Des études récentes ont repris les roches forées lors des DSDP Legs 67 et 84 et montrent que le soubassement du bassin d'avant-arc du Guatemala-Nicaragua est composé de roches ultramafiques et mafiques (OIB et arc), dont les âges isotopiques vont du Trias au Crétacé supérieur. Finalement, les péridiotites de Santa Elena forment la limite sud du MCOT par rapport aux terrains de Manzanillo et Nicoya. Elles contiennent des serpentinites et localement des dunites et chromites à affinité abyssale et de fore-arc. Le SSM témoigne d'une collision entre un arc insulaire d'âge Jurassique moyen et le Patuca Terrane, un fragment de la marge active nord-américaine. Le SSM et le South Motagua Mélange ont des caractéristiques en commun avec les zones de suture de la façade pacifique de l'Amérique du nord (E-Franciscan et Vizcaino mélanges), notamment les âges Mésozoïques du métamorphisme HP/BT et les blocs de roches d'arc. Ce fait nous conduit à penser qu'il s'agit d'une grande zone de suture qui était à l'origine continue sur toute la marge ouest-américaine, mais légèrement diachrone. Cette suture implique l'arrivée et la collision d'un arc intraocéanique exotique (Guerrero-Phoenix) qui est à l'origine de la Plaque Pacifique qui s'ouvrait en back arc par rapport à celui-ci. La disposition actuelle des fragments de cette suture est due à la migration vers le nord du décrochement actif senestre entre la Plaque nord-américaine et la Plaque Caraïbe. K. Flores, 2009 Mesozoic oceanic terranes of southern central America Résumé Grand Public La présente thèse est le résultat de travaux de terrain effectués de 2005 à 2008 au nord-est et au sud du Nicaragua et au nord du Costa Rica, en Amérique Centrale, des analyses pétrologiques et géochimiques en laboratoire ainsi que de la modélisation de l'évolution géodynamique. La région étudiée se situe en bordure nord - ouest de la Plaque Caraïbe moderne. Dans la majorité des publications récentes cette région est représentée comme un vaste bloc continental (le "Bloc Chortis") qui serait limité, (i) au nord, par la faille décrochante de Motagua, la limite actuelle entre la Plaque Nord-Américaine et la Plaque Caraïbe, et (ii) au sud, par une suture hypothétique qui se trouverait aux confins entre le Nicaragua et le Costa Rica. La région du Costa Rica a été considérée presque entièrement comme une partie du Plateau Caraïbe ("Caribbean Large Igneous Province" (CLIP)). L'étude détaillée des affleurements nous a permis de mettre en évidence : - Au nord-est du Nicaragua (Siuna) : Des roches océaniques datées du Jurassique moyen, grâce aux faunes à radiolaires qui ont été extraites des radiolarites rouges. Ces roches ont subi un métamorphisme de haute pression typique des zones de collision. L'étude radio-isotopique Ar/Ar a permis de dater la collision du Crétacé basal (139 Ma). - Au sud du Nicaragua : Des roches océaniques d'âge Trias terminal (200 millions d'années), également datées à l'aide de faunes à radiolaires. Il s'agit actuellement des roches océaniques les plus anciennes connues de l'Amérique Centrale. - L'étude géochimique et les âges des fossiles démontrent que le tiers septentrional du Costa Rica possède un soubassement construit d'au moins deux terrains (Nicoya et Manzanillo), qui ont des caractéristiques de Plateau océanique (Nicoya) et d'arc volcanique du Crétacé moyen (Manzanillo). Ces deux terrains sont plus anciens que le CLIP. En conclusion, nous constatons que la région étudiée est constituée d'un puzzle de 3 blocs continentaux et d'un vaste terrain océanique composite que nous appelons Mesquito Composite Oceanic Terrane (MCOT). En plus, nous définissons les terrains de Nicoya et de Manzanillo comme plus âgés et distincts du CLIP. Le MCOT est caractérisé par la présence de roches du manteau supérieur (les serpentinites) et de la croûte océanique, ainsi que des morceaux d'arcs, d'âge allant du Trias supérieur au Crétacé. Ce terrain est comparable à d'autres zones de suture de la façade pacifique de l'Amérique du nord, notamment en ce qui concerne les âges Mésozoïques, le métamorphisme de haute pression et l'association de roches mantéliques et crustales océaniques. Ce fait nous conduit à penser qu'il s'agit d'une grande zone de suture qui était à l'origine continue sur toute la marge ouest-américaine. Cette suture implique l'arrivée et la collision d'un arc infra-océanique exotique qui serait à l'origine de la Plaque Pacifique qui se serait ouverte en bassin d'arrière arc par rapport à celui-ci. La disposition actuelle des fragments de cette suture est due à la migration vers le nord du décrochement actif senestre entre la Plaque nord-américaine et la Plaque Caraïbe.
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Wars are often associated with a rhetoric of renewal or new beginnings. This essay explores this claim through the lens of civil religion and a recent book by Carolyn Marvin and David Ingle, Blood Sacrifice and the Nation, which combines Emile Durkheim with Réné Girard in proposing that modern national cohesion depends on blood sacrifice. I unpack some of the paradoxes raised by this theory of national renewal in the context of 9/11, with a special focus on the sacred status of the flag and the special attention given to uniformed serviceman in the American body politic.
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Contains information about the staff and athletes of the Iowa Hawkeyes Track and Field team for the 1984/85 academic school year. Also includes past year's results, team records, quick facts and schedule.
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Entrevista a Radio Nikosia
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The objective of this work was to assess the performance of panel clones under crowns resistant to South American leaf blight (Microcyclus ulei). The experiment was carried out with 18 panel clones crown-budded with Hevea pauciflora x H. guianensis, in a Xanthic Ferralsol (Oxisol) in Manaus, AM, Brazil. The following parameters were evaluated: dry rubber yield, plant nutritional status, and anatomical and physiological characteristics of the latex vessels. In the first three years of evaluation, the panel clones IAN 2878, IAN 2903, CNS AM 7905, CNS AM 7905 P1, and PB 28/59 showed the highest dry rubber yield potential, while the clones IAN 6158, IAN 6590, and IAN 6515 should not be recommended for crown budding. Higher potassium and copper foliar content in panel clones were associated to an increase in dry rubber yield. The simultaneous evaluation of anatomical and physiological characteristics of latex is fundamental for the selection of panel clones in the Amazon region. Crown budding is an efficient technology for South American leaf blight management in endemic regions.
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Award-winning
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American English exhibits a great dialectal diversity, easily perceived in lexicon; so that questions are raised about which regionalisms are part of the mythical SAE and which are not. A small sample of regionalisms is checked against three standard dictionaries in order to determine the role regionalisms play in SAE.
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The objective of this work was to assess the possible transport of cyanogenic glycosides from leaves of rubber tree crown clones (Hevea spp.) resistant to South American leaf blight to the trunk of the panel clones in which they are grafted. The cyanogenic potential (HCNp) of the crown clones was determined in the trunk bark, at different distances from the cambium, and its gradient was evaluated along the trunk. The correlation between the HCNp of the crown leaves and that of the trunk bark was also evaluated. HCNp determined in leaves showed a wide range variation in the species studied as crown clones, with the lowest values registered in H. nitida clones, and the highest ones in H. rigidifolia. In the trunk bark, the tissue layer nearer the cambium showed higher HCNp values. A positive basipetal gradient was observed along the trunk, i.e., there was an increase in HCNp from the apex toward the base. Although the grafted crowns influence the cyanogenic potential of the trunk bark of panel clones, the absence of correlation between the HCNp of the leaves and trunk bark indicates that the crown is not the main source of the cyanogenic glycosides found in the trunk.
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Cognitive radio is a wireless technology aimed at improvingthe efficiency use of the radio-electric spectrum, thus facilitating a reductionin the load on the free frequency bands. Cognitive radio networkscan scan the spectrum and adapt their parameters to operate in the unoccupiedbands. To avoid interfering with licensed users operating on a givenchannel, the networks need to be highly sensitive, which is achieved byusing cooperative sensing methods. Current cooperative sensing methodsare not robust enough against occasional or continuous attacks. This articleoutlines a Group Fusion method that takes into account the behavior ofusers over the short and long term. On fusing the data, the method is basedon giving more weight to user groups that are more unanimous in their decisions.Simulations have been performed in a dynamic environment withinterferences. Results prove that when attackers are present (both reiterativeor sporadic), the proposed Group Fusion method has superior sensingcapability than other methods.
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Cognitive radio networks (CRN) sense spectrum occupancy and manage themselves to operate in unused bands without disturbing licensed users. The detection capability of a radio system can be enhanced if the sensing process is performed jointly by a group of nodes so that the effects of wireless fading and shadowing can be minimized. However, taking a collaborative approach poses new security threats to the system as nodes can report false sensing data to force a wrong decision. Providing security to the sensing process is also complex, as it usually involves introducing limitations to the CRN applications. The most common limitation is the need for a static trusted node that is able to authenticate and merge the reports of all CRN nodes. This paper overcomes this limitation by presenting a protocol that is suitable for fully distributed scenarios, where there is no static trusted node.
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Spectrum is an essential resource for the provision of mobile services. In order to control and delimit its use, governmental agencies set up regulatory policies. Unfortunately, such policies have led to a deficiency of spectrum as only few frequency bands are left unlicensed, and these are used for the majority of new emerging wireless applications. One promising way to alleviate the spectrum shortage problem is adopting a spectrum sharing paradigm in which frequency bands are used opportunistically. Cognitive radio is the key technology to enable this shift of paradigm.Cognitive radio networks are self-organized systems in which devices cooperate to use those spectrum ranges that are not occupied by licensed users. They carry out spectrum sensing in order to detect vacant channels that can be used for communication. Even though spectrum sensing is an active area of research, an important issue remains unsolved: the secure authentication of sensing reports. Not providing security enables the input of false data in the system thus empowering false results. This paper presents a distributed protocol based on wireless physical layer security, symmetric cryptography and one-way functions that allows determining a final sensing decision from multiple sources in a quick and secure way, as well as it preserves users¿ privacy.
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Spectrum scarcity demands thinking new ways tomanage the distribution of radio frequency bands so that its use is more effective. The emerging technology that can enable this paradigm shift is the cognitive radio. Different models fororganizing and managing cognitive radios have emerged, all with specific strategic purposes. In this article we review the allocation spectrum patterns of cognitive radio networks andanalyse which are the common basis of each model.We expose the vulnerabilities and open challenges that still threaten the adoptionand exploitation of cognitive radios for open civil networks.
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Cognitive radio networks sense spectrum occupancyand manage themselves to operate in unused bands without disturbing licensed users. Spectrum sensing is more accurate if jointly performed by several reliable nodes. Even though cooperative sensing is an active area of research, the secureauthentication of local sensing reports remains unsolved, thus empowering false results. This paper presents a distributed protocol based on digital signatures and hash functions, and ananalysis of its security features. The system allows determining a final sensing decision from multiple sources in a quick and secure way.