21,729 research outputs found
Television: Peer-To-Peer’s Next Challenger
The entertainment industry has obsessed over the threat of peer-to-peer file sharing since the introduction of Napster in 1999. The sharing of television content may present a compelling case for fair use under the long-standing Betamax decision. Some argue that television sharing is fundamentally different than the distribution of music or movies since television is often distributed for free over public airwaves. However, a determination of fair use is unlikely because of the fundamental differences between recording a program and downloading it, recent regulation to suppress unauthorized content distribution and shifts in the television market brought on by new technology
Conservation of Lactuca watsoniana Trelease, an Azorean priority species : phylogenetics, population genetics and propagation
Tese de Doutoramento, Biologia, 28 de maio de 2018, Universidade dos Açores.Lactuca watsoniana Trel., é uma herbácea perene, endémica do Arquipélago dos Açores. Localmente denominada de “Alfacinha”, pode ser encontrada em quatro das nove ilhas do Arquipélago dos Açores (Faial, Pico, Terceira e São Miguel), estando possivelmente extinta da ilha de São Jorge. O tamanho total estimado das populações é de 500 a 2000 indivíduos, mas observações recentes no campo indicam que poderão ser menos de 500 indivíduos. Considerada como taxon prioritário na Directiva Habitats (Annex B-II) bem como na Convenção de Berna em termos de conservação e está listada como ameaçada (EN B2ab (i, ii, iii); C2a(i)) na Lista Vermelha da IUCN 2017. Atualmente, a Lactuca watsoniana encontra-se restrita a zonas húmidas, ravinas profundas e estreitas, crateras zonas declivosas, prados naturais de Festuca, matos de Erica e florestas de Juniperus entre 600-800 m. Está ameaçada por perda e degradação de habitat, resultante de expansão dos pastos, invasão por espécies exóticas, introdução de herbívoros e distúrbio de áreas sensíveis por turistas e locais. Neste trabalho investigaram-se os seguintes tópicos: i) propagação vegetativa por sementes; ii) genética de populações; e iii) filogenética e filogeografia. Foi estabelecido um protocolo eficaz e exequível para propagação por via seminal, germinando as sementes com 0.1 mg l-1 GA3, ethephon, e um filtro de luz vermelha e um regime de temperatura alterna de 15/10°C, com um fotoperíodo de 12 horas. Este protocolo permitiu a produção de centenas de plântulas viáveis que foram replantadas na população de origem. Dada a necessidade de proceder ao reforço das populações naturais em algumas ilhas, pretendeu-se definir se existiam riscos de contaminação genética resultante da troca de material entre as diferentes ilhas, para isso estudou-se a estrutura e variabilidade genética das populações, usando 8 microssatélites nucleares, desenvolvidos especificamente para a L. watsoniana. Os resultados mostraram uma clara separação entre as várias ilhas dos Açores, estando a maior variação genética dentro das populações (55.0%), mas com níveis relativamente altos de variação entre os clusters (27.3%). Evidenciando um grau de diferenciação entre as populações elevado e fluxo genético com valores inferiores a 1, bem como a existência de isolamento e barreiras geográficas. De modo a clarificar a posição taxonómica da L. watsoniana, nomeadamente em relação a espécies próximas da Europa, Norte da América e de outros Arquipélagos da Macaronésia (Canárias), recorremos a marcadores moleculares nucleares (ITS) e quatro do cloroplasto. Na análise das sequências combinadas de ITS e do cloroplasto (Parsimónia, Máxima verosimilhança e Inferência Baeysiana) o taxon dos Açores, mostrou a existência de um padrão filogeográfico através do arquipélago, com a presença de 5 haplótipos distintos para a L. watsoniana, quatro endémicos em apenas uma ilha (Faial, Pico, Terceira e São Miguel) e um haplótipo com informação genética partilhada do Faial e Pico, bem como uma relação filogenética, bem suportada, com as Lactuca Norte Americanas.ABSTRACT: Lactuca watsoniana Trel., is a perennial herb, endemic to the Azores archipelago. Locally called "Alfacinha", the species is restricted to only four of the nine islands of the archipelago (São Miguel, Terceira, Pico and Faial) and is possibly extinct in São Jorge Island. Estimates of its total population size are 500 to 2,000 individuals, but recent field observations indicate that it can be fewer than 500 individuals. It is therefore considered a priority species for conservation and was listed as endangered on the IUCN Red List 2017. Furthermore, it was included in Annex II of the EC Habitats Directive and is protected under the Berne Convention. Lactuca watsoniana is currently restricted to the steep slopes of craters and ravines in temperate juniper rain forest between 600-800 m of altitude. The species is threatened by habitat loss and degradation resulting from changes in land use, namely expansion of pasture, invasion by exotic species, consumption by introduced herbivores and disturbance of sensitive areas by tourists and locals.
In this thesis, we investigated the following topics: i) seed propagation; ii) population genetics; and iii) phylogenetics and phylogeography. We established and efficient and feasible seed propagation protocol by germinating the seeds germinate seeds with 0.1 mg l-1 GA3, ethephon, a red-light filter and a temperature regime of 15/10°C, and 12 hours’ photoperiod. This protocol allowed producing hundreds of viable seedlings that were reintroduced in the source population. Given the need to reinforce natural populations in some of the islands, we aimed to find out if any outbreeding risks existed, resulting from material exchanges between the different islands. For that, we studied the genetic structure and variability of the populations, using eight nuclear microsatellites, developed specifically, for Lactuca watsoniana. Our findings showed a clear separation among the islands, with the largest proportion of genetic variation found within populations (55.0%) but with relatively high levels of genetic variation both among clusters (27.3%). Furthermore, a high variability between the populations, a gene flow value below one, and the presence of geographical isolation and barriers were estimated. In order to clarify the taxonomic position of L. watsoniana, namely the phylogeographic and phylogenetic relationship with the morphologically similar species from Europe, North America and the geographically close taxa from the Canary Islands, we used one nuclear region (ITS) and four chloroplast markers. Parsimony, Maximum likelyhood and Bayesian Inference analyses were conducted and revealed a strongly supported monophyletic Lactuca clade, and a clear separation of Macaronesian endemic Lactuca in sister clades. Lactuca watsoniana, endemic to Azores, showed a phylogeographic pattern across the archipelago, with the presence of five different haplotypes for L. watsoniana: four single island endemics (Faial, Pico, Terceira e São Miguel) and one occurring on both Faial and Pico and a strongly supported phylogenetic relationship with North America Lactuca.Fundo Regional da Ciência pelo financiamento da Bolsa de Doutoramento (M3.1.2/F/032/2011 e FEDER funds through the Operational Programme for Competitiveness Factors - COMPETE
Cross-Nativity Marriages and Human Capital Levels of Children
A common perception about immigrant assimilation is that association with natives necessarily speeds the process by which immigrants become indistinguishable from natives. Using 2000 Census data, this paper casts doubt on this presumption by examining the effect of an immigrant's marriage to a native, a measure of social integration, on dropout rates of children from these marriages. Although second-generation immigrants with one native parent generally have lower dropout rates than those with two foreign-born parents, the relationship reverses when steps are taken to control for observable and unobservable background characteristics. That is, immigrants that marry natives have children that are more likely to dropout of high school than immigrants that marry other immigrants. Moreover, gender differences in the effect of marriage to a native disappear in specifications which control for the endogeneity of the marriage decision.immigration, intermarriage, education
I’ll marry you if you get me a job: cross-nativity marriages and immigrant employment rates
This paper tests whether marriage to a native affects the probability that an immigrant is employed. We provide a theoretical background which explains how marriage to a native may positively or negatively affect an immigrant’s employment probability. Utilizing the 2000 U.S. Census, we first look at the effect of cross-nativity marriages on employment using a linear probability model. Then, we estimate a two stage least squares model instrumenting for cross-nativity marriages using local marriage market conditions. Results from a linear probability model controlling for the usual measures of human capital and immigrant assimilation suggest that marriage to a native increases the employment probability of an immigrant by
approximately 5 percentage points. When controlling for the endogeneity of the intermarriage decision, marriage to a native increases the employment probability by about 11 percentage points. We provide alternative explanations and suggest policy implications
Real estate market and the relevance of local features in a hedonic prices quantil-spatial analysis – the case of Belo Horizonte – Brazil
The main motivation of this paper is to identify how relevant the localization of a specific estate is in its market value. Furthermore, it aims to understand better how economic aspects influence and are influenced by urban space. In order to do so, a myriad of concepts is drawn from a variety of fields of science: from geography to architecture, from urbanism to economics, as well as methodologies, which are borrowed from statistics, econometrics and geoprocessing. The proposal of the paper follows the hedonic prices function literature, but suggests that a synthesis of the perception of urban amenities can be expressed by the element of the neighbourhood (as proposed by Lynch, 1997). A number of models are presented, tested and commented. The one with the best fit is the spatial error-lag (Anselin, 1988) specified with a ranking of neighbourhood income. A quantil analysis adds considerably to the understanding of the model.real estate market, neighbourhoods, spatial econometrics, quantil analysis, Belo Horizonte
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