1,201 research outputs found

    LAND USE-- A PERSPECTIVE FROM SCOTLAND

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    Land Economics/Use,

    Enhanced binding revisited for a spinless particle in non-relativistic QED

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    We consider a spinless particle coupled to a quantized Bose field and show that such a system has a ground state for two classes of short-range potentials which are alone too weak to have a zero-energy resonance

    Geomorphology, Sedimentary Structures, and Genesis of Dome Dunes in Western Canada

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    Dome dunes in four stabilized, inland dune fields in western Canada are predominantly composed of horizontal to low-angle cross-strata, indicating that slip face development was rare. Dip angles of lee side deposits decrease upward in the dome dunes. The spread of dip directions increases with elevation in the dunes, spanning 360° for topset deposits. Sedimentary structures indicative of moisture (adhesion laminae) and vegetation (scour surfaces) occur in the dunes and denivation features are also present. Sediment adhesion is responsible for the maintenance of the dome morphology. Sediment sorting within the dome dunes is poorer than in other local dune types in the vicinity, suggesting that less reworking/ineffective selective transport occurred and that the dome dunes are more efficient in retaining sediment. The rarity of slip face and grainfall deposits and the abundance of low angle deposits indicate that preferential accumulation of sediment at the top of the lee side did not occur. Development of domal morphology is a consequence of the inhibition of slip face development. In inland, relatively moist boreal environments, the primary factor limiting or precluding sediment accumulation at the crest of the dunes is a low rate of sedimentation.Les dunes en dôme situées dans des champs de dunes stabilisés à l'intérieur des terres sont en grande partie constituées de stratifications entrecroisées subhorizontales, indiquant ainsi un faible développement de la face sous le vent. L'angle de pendage du versant sous le vent tend à diminuer vers la partie supérieure des dunes. Les directions de pendage s'étalent avec l'altitude, jusqu'à 360° dans les dépôts sommitaux. On trouve dans ces dunes des structures sédimentaires indicatrices de la présence d'humidité (feuillets adhérents) et de végétation (surface d'affouillement) ainsi que des formes de dénivation. La préservation de la morphologie des dunes est attribuable à l'adhésivité des sédiments. La granulométrie des dunes en dôme n'est pas aussi complète que dans les autres types de dunes de la région, indiquant ainsi que le remaniement des sédiments et leur transport sélectif ont été moins efficaces et qu'il y a eu meilleure rétention des sédiments. La faible accumulation par écoulement granulaire et sur la face sous le vent et la forte accumulation par strates subhorizontales montrent qu'il n'y a pas eu de mise en place préférentielle de sédiments au sommet du versant sous le vent. L'élaboration de la morphologie en dôme est attribuable au faible développement de la face sous le vent. À l'intérieur des terres, en milieu boréal relativement humide, l'accumulation des sédiments est minime-au sommet des dunes, surtout en raison du faible taux de sédimentation.Kuppeldunen in vier stabilisierten Inlanddûnenfeldern in West-Kanada bestehen vor allem aus hori-zontalen bis gering geneigten Kreuzschichtungen, was darauf hinweist, dass abrutschende Entwicklung selten war. Die Neigungswinkel der Ablagerungen auf der Leeseite nehmen in den Kuppeldunen nach oben hin ab. Die Ausdehnung der Neigungsrichtungen nimmt mit der Hôhe der Dûnen zu, bis zu 360° in den hôchsten Ablagerungen. Es gibt in den Dùnen Sedimentstrukturen, die auf Feuchtigkeit (haftende Blatter) und Vegetation (Schleifoberflàchen) hinweisen, und auch Denivationserscheinungen sind vorhanden. Der Sedimentadhâsion wird die Erhaltung der Kuppelmorphologie zugeschrieben. Die Sedimentsortierung innerhalb der Kuppeldunen ist geringer als in anderen lokalen Dùnen-typen in der Nàhe, so dass man annimmt, dass weniger Umarbeitung/ ineffektiver selektiver Transport geschah und dass die Kuppeldunen erfolgreicher Sediment zurùckhalten. Das seltene Vorkommen abrutschender und kôrniger Ablagerungen und die Fùlle von gering geneigten Ablagerungen zeigen, dass bevorzugte Sedimentakkumulation an der Spitze der Leeseite nicht vorkam. Die Entwicklung der Kuppelmorphologie ergibt sich aus der Verhinderung abrutschender Entwicklung. Im Inland, in relativ feuchter nôrdlicher Umwelt ist der hauptsachliche Faktor der Begren-zung oder Verhinderung der Sedimentakkumulation an der Spitze der Dùnen eine niedrige Sedimentierungsrate

    Taxa de natalidade no rebanho bovino no Pantanal: nutrição, sanidade e genética.

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    No século XVIII com a decadência das lavras auríferas de Cuiabá, a população local passou a desenvolver a agricultura no vale do Guaporé e a pecuária na planície pantaneira, região salubre e com pastagens nativas de melhor qualidade para a criação de gado. No sentido norte-sul, todo o Pantanal foi ocupado pela pecuária de corte extensiva promovendo até as primeiras décadas do último século a indústria do charque e de outros subprodutos como crina, couro e extratos. A criação de gado floresceu tanto que na década de 40 representava 6% do rebanho nacional e 90% do então estado de Mato Grosso. Com o desenvolvimento da pecuária no Triângulo Mineiro e noroeste de São Paulo, o gado do Pantanal passou a ser comercializado "em pé" para aquelas regiões impulsionado, posteriormente, com a construção da estrada de ferro Noroeste do Brasil. A taxa de natalidade no rebanho nelorado em pastagens nativas no Pantanal está em torno de 55%, mas varia de 40% a 60% em função da proporção de fitofisionomias e do grau de propensão à inundação das invernadas. Períodos de seca melhoram o índice de natalidade em todo o Pantanal pela disponibilização de mais pastagens de melhor qualidade nas áreas baixas sujeitas a inundação. Outra característica da região é a idade tardia na primeira cria com aproximadamente quatro anos (Tullio, 1986; Pott et al., 1987a; Abreu et al., 2000). O objetivo deste trabalho é revisar os trabalhos publicados sobre o assunto.bitstream/item/79415/1/COT29.pd

    Contemporary Occupational Carcinogen Exposure and Bladder Cancer: A Systematic Review and Meta-analysis

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    Importance: Bladder cancer (BC) is a common disease. Despite manufacturing and legislative changes to workplace hygiene, many BCs still arise through occupational carcinogen exposure. Objective: To profile contemporary risks of occupational BC. Data Sources: A systematic review using PubMed, Medline, Embase, and Web of Science was performed in October 2012 (initial review) and May 2014 (final review) and was updated in June 2015. Study Selection: We identified 263 eligible articles. We excluded reports in which BC or occupation were not the main focus, and those with insufficient case, risk, or confidence interval data. We selected the most recent data from populations with multiple reports. Data Extraction and Synthesis: Reports were selected by 2 of us independently. We combined odds ratios and risk ratios (RRs) to provide pooled RRs, using maximally adjusted RRs in a random effects model. Heterogeneity and publication bias were assessed using I2 and Begg and Egger tests. Risk estimates were annotated by occupational class using Nordisk Yrkesklassificering, or Nordic Occupational Classification, and International Standard Classifications of Occupations (NYK and ISCO-1958) Codes. Main Outcomes and Measures: Occupations were profiled by BC incidence and mortality risk over time. After data collection, we detected a sex difference in these profiles and recorded this as a secondary outcome. Results: Meta-analysis revealed increased BC incidence in 42 of 61 occupational classes and increased BC-specific mortality in 16 of 40 occupational classes. Reduced incidence and mortality were seen in 6 of 61 and 2 of 40 classes, respectively. Risk varied with sex and was greatest in men (standardized incidence ratio, 1.03 [95% CI, 1.02-1.03]; P < .001]). From the 1960s to the 1980s, there was a steady decline in standarized incidence ratio (SIR) for both sexes. This trend reversed from the 1980s, as in the decade 2000 to 2010 the SIR increased to 1.13 (95% CI, 1.07-1.19) for men and 1.27 (95% CI, 1.12-1.43) for women. In contrast, mortality risk declined for both sexes from the 1960s to the 1990s. The overall risk of BC mortality was also greater for men (standardized mortality ratio [SMR], 1.32 [95% CI, 1.18-1.48]) than for women (SMR, 1.14 [95% CI, 0.80-1.63]). Limitations include possible publication bias, that reports stratify workers mostly by job title not task, that not all studies adjusted for smoking, and that the population was mostly derived from Western nations. Conclusions and Relevance: The profile of contemporary occupations with increased BC risk is broad and differs for incidence and mortality. Currently the incidence seems to be increasing, and this increase is occurring faster in women than men. Improved detection mechanisms and screening are possible reasons for this. Workers with aromatic amine exposure have the highest incidence, while those exposed to polycyclic aromatic hydrocarbons and heavy metals have the greatest mortality

    Binding threshold for the Pauli-Fierz operator

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    For the Pauli-Fierz operator with a short range potential we study the binding threshold as a function of the fine structure constant α\alpha and show that it converges to the binding threshold for the Schr\"odinger operator in the small α\alpha limit
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