92 resultados para MULTIPOLAR EXPANSION


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A main mechanism behind the change in European and North American societies in the second half of the 20th century is the educational expansion, i.e. the increase in educational opportunities and the higher demand for education. Whereas other abstract social processes like modernization have been widely theorized in social science literature, the educational expansion and its consequences in particular have not been well studied. Therefore the main aim of this compilation is to deal with the question of whether the demands of the educational reforms have been fulfilled and which other consequences the educational expansion has had. This book will focus on consequences of the educational expansion for individuals and their life courses as well as for the social structure and other societal areas such as culture and politics. Aspects that will be analysed in the light of educational expansion include participation in education, educational inequalities, labour market outcomes, educational returns, and gender differences as well as crime, life expectancy, and lifestyles. Countries analysed in the book include West European countries like Germany, France, Italy and Spain, East European countries (Hungary, Poland, and the Czech Republic) as well as the US.

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Major environmental events that fragment populations among multiple island habitats have potential to drive large-scale episodes of speciation and adaptive radiation. A recent palaeolimnological study of sediment cores indicated that Lake Malawi underwent major climate-driven desiccation events 75 000-135 000 years ago that lowered the water level to at least 580 m below the present state and severely reduced surface area. After this period, lake levels rose and stabilized, creating multiple discontinuous littoral rocky habitats. Here, we present evidence supporting the hypothesis that establishment and expansion of isolated philopatric rock cichlid populations occurred after this rise and stabilization of lake level. We studied the Pseudotropheus (Maylandia) species complex, a group with both allopatric and sympatric populations that differ in male nuptial colour traits and tend to mate assortatively. Using coalescent analyses based on mitochondrial DNA, we found evidence that populations throughout the lake started to expand and accumulate genetic diversity after the lake level rise. Moreover, most haplotypes were geographically restricted, and the greatest genetic similarities were typically among sympatric or neighbouring populations. This is indicative of limited dispersal and establishment of assortative mating among populations following the lake level rise. Together, this evidence is compatible with a single large-scale environmental event being central to evolution of spatial patterns of genetic and species diversity in P. (Maylandia) and perhaps other Lake Malawi rock cichlids. Equivalent climate-driven pulses of habitat formation and fragmentation may similarly have contributed to observed rapid and punctuated cladogenesis in other adaptive radiations.

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Meningioma is the most frequently observed primary brain tumour in cats. Usually, it is associated with an intracranial expansion with consequent brain compression, oedema and brain herniation. Typical features of feline intracranial meningiomas are hyperostosis of the adjacent bone and intratumoral mineralisation. We describe a 13-year-old male neutered cat with a 1-year history of behavioural change. At clinical and neurological examination the cat showed signs consistent with right-sided forebrain lesion. Magnetic resonance images showed a right-sided extra-axial contrast enhancing mass in the region of the frontotemporal lobe. The overlying bone of the calvarium showed a marked defect with extracranial expansion of the tissue. Surgery was performed and the tumour could be exposed by a right-sided temporal approach. After extension of the bony defect the mass could be removed properly. The cat recovered well from surgery and a 12-month follow-up showed no persistent neurological deficits. Histopathological assessment of the tumour revealed a transitional grade 1 meningioma. Despite osteolysis and extracranial expansion of the tumour differentials should include menigioma in feline intracranial neoplasms.

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Hydrodynamics can be consistently formulated on surfaces of arbitrary co-dimension in a background space-time, providing the effective theory describing long-wavelength perturbations of black branes. When the co-dimension is non-zero, the system acquires fluid-elastic properties and constitutes what is called a fluid brane. Applying an effective action approach, the most general form of the free energy quadratic in the extrinsic curvature and extrinsic twist potential of stationary fluid brane configurations is constructed to second order in a derivative expansion. This construction generalizes the Helfrich-Canham bending energy for fluid membranes studied in theoretical biology to the case in which the fluid is rotating. It is found that stationary fluid brane configurations are characterized by a set of 3 elastic response coefficients, 3 hydrodynamic response coefficients and 1 spin response coefficient for co-dimension greater than one. Moreover, the elastic degrees of freedom present in the system are coupled to the hydrodynamic degrees of freedom. For co-dimension-1 surfaces we find a 8 independent parameter family of stationary fluid branes. It is further shown that elastic and spin corrections to (non)-extremal brane effective actions can be accounted for by a multipole expansion of the stress-energy tensor, therefore establishing a relation between the different formalisms of Carter, Capovilla-Guven and Vasilic-Vojinovic and between gravity and the effective description of stationary fluid branes. Finally, it is shown that the Young modulus found in the literature for black branes falls into the class predicted by this approach - a relation which is then used to make a proposal for the second order effective action of stationary blackfolds and to find the corrected horizon angular velocity of thin black rings.