86 research outputs found
Combined influence of meso-scale circulation and bathymetry on the foraging behaviour of a diving predator, the king penguin (Aptenodytes patagonicus)
Investigating the responses of marine predators to environmental features is of key importance for understanding their foraging behaviour and reproductive success. In this study we examined the foraging behaviour of king penguins breeding at Kerguelen (southern Indian Ocean) in relation to oceanographic and bathymetric features within their foraging ambit. We used ARGOS and Global Positioning System tracking together with Time-Depth-Temperature-Recorders (TDR) to follow the at-sea movements of incubating and brooding king penguins. Combining the penguin behaviour with oceanographic data at the surface through satellite data and at depth through in-situ recordings by the TDRs enabled us to explore how these predators adjusted their horizontal and vertical foraging movements in response to their physical environment. Relating the observed behaviour and oceanographic patterns to local bathymetry lead to a comprehensive picture of the combined influence of bathymetry and meso-scale circulation on the foraging behaviour of king penguins.
During both breeding stages king penguins foraged in the area to the south-east of Kerguelen, where they explored an influx of cold waters of southern origin interacting with the Kerguelen Plateau bathymetry. Foraging in the Polar Front and at the thermocline was associated with high prey capture rates. However, foraging trip orientation and water mass utilization suggested that bathymetrically entrained cold-water features provided the most favourable foraging locations. Our study explicitly reports the exploration of bathymetry-related oceanographic features by foraging king penguins. It confirms the presence of Areas of Ecological Significance for marine predators on the Kerguelen Plateau, and suggests the importance of further areas related to the cold-water flow along the shelf break of the Kerguelen Plateau
How Differences in Property Taxes within Cities Affect Urban Sprawl?
This article attempts a formal analysis of the connection between the differentiated property tax rates within urban areas and urban spatial pattern in U.S. cities. We first develop a duocentric-city model where the Central Business District (CBD) is located at the origin while the Suburban Business District (SBD) is at the other end of the city. We show that the ratio between the property tax in the suburbs and in the center has an ambiguous impact on the size of the city. We then test this model empirically to determine this sign by using a dataset of effective property tax rates we developed using GIS techniques for central cities and suburbs in 445 urbanized areas. The empirical analysis estimates the link between these two variables by controlling for variables such as population, income, agricultural rent, commuting cost, climate, crime, and employment structure. Results from the empirical analyses suggest that a lower property tax rate in the suburbs in comparison to the central city is associated with more expansive urban growth and greater level of decentralization of population and employment
Myths and misconceptions about hypnosis and suggestion: Separating fact and fiction
We present 21 prominent myths and misconceptions about hypnosis in order to promulgate accurate information and to highlight questions for future research. We argue that these myths and misconceptions have (a) fostered a skewed and stereotyped view of hypnosis among the lay public, (b) discouraged participant involvement in potentially helpful hypnotic interventions, and (c) impeded the exploration and application of hypnosis in scientific and practitioner communities. Myths reviewed span the view that hypnosis produces a trance or special state of consciousness and allied myths on topics related to hypnotic interventions; hypnotic responsiveness and the modification of hypnotic suggestibility; inducing hypnosis; and hypnosis and memory, awareness, and the experience of nonvolition. By demarcating myth from mystery and fact from fiction, and by highlighting what is known as well as what remains to be discovered, the science and practice of hypnosis can be advanced and grounded on a firmer empirical footing
The Impact of Worker Effort on Public Sentiment Towards Temporary Migrants
Temporary and circular migration programs have been devised by many destination countries and supported by the European Commission as a policy to reduce welfare and social costs of immigration in destination countries. In this paper we present an additional reason for proposing temporary migration policies based on the characteristics of the foreign labor-effort supply. The level of effort exerted by migrants, which decreases over their duration in the host country, positively affects production, real wages and capital owners' profits. We show that the acceptance of job offers by migrants result in the displacement in employment of national workers. However it increases the workers' exertion, decreases prices and thus can counter anti-immigrant voter sentiment. Therefore, the favorable sentiment of the capital owners and the local population towards migrants may rise when temporary migration policies are adopted
Population dynamics in Germany: the role of immigration and population momentum
The effects of changes in rates of mortality, fertility, and migration depend not only on the age-specific patterns and levels of these rates, but on the age structure of the population. In order to remove the influences of the age structure and concentrate on the effects of the demographic rates themselves, a common practice is to analyze the influences of the rates for a standard age structure. This paper analyzes current and future population changes in Germany, using a stationary population equivalent model (SPE) that shows long-term effects of current fertility, mortality, and international migration patterns. Results indicate that the German population will eventually decline because of below replacement fertility, if net immigration does not counteract this decrease. This means, for instance, that the long-term stationary population levels for Germany will decrease by approximately 6.5 million during a decade in which current fertility, mortality, and international migration levels prevail. The paper also reports how various other assumptions for mortality, fertility, and international migration affect the SPE model for Germany. Copyright Springer Science+Business Media B.V. 2006German population change, International migration, Below replacement fertility, Mortality, Fertility,
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