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Search Results: 1 - 10 of 291 matches for " Jake Reschke "
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Velocity addition formulas in Robertson-Walker spacetimes
David Klein,Jake Reschke
Mathematics , 2015, DOI: 10.1063/1.4926352
Abstract: Universal velocity addition formulas analogous to the well-known formula in special relativity are found for four geometrically defined relative velocities in a large class of Robertson-Walker spacetimes. Explicit examples are given. The special relativity result is recovered as a special case, and it is shown that the spectroscopic relative velocity, in contrast to three other geometric relative velocities, follows the same addition law as in special relativity for comoving observers in Robertson-Walker cosmologies.
Distinguished Line Bundles for Complex Surface Automorphisms
Paul Reschke
Mathematics , 2012,
Abstract: We equate dynamical properties (e.g., positive entropy, existence of a periodic curve) of complex projective surface automorphisms with properties of the pull-back actions of such automorphisms on line bundles. We use the properties of the cohomological actions to describe the measures of maximal entropy for automorphisms with positive entropy.
Salem Numbers and Automorphisms of Complex Surfaces
Paul Reschke
Mathematics , 2012,
Abstract: For two-dimensional complex tori, we characterize the set of all values of positive entropy that arise from automorphisms. For K3 surfaces, we give suffcient conditions for a positive value to be the entropy of some automorphism.
Salem Numbers and Abelian Surface Automorphisms
Paul Reschke
Mathematics , 2014,
Abstract: We classify two-dimensional complex tori admitting automorphisms with positive entropy in terms of the entropies they exhibit. For each possible positive value of entropy, we describe the set of two-dimensional complex tori admitting automorphisms with that entropy.
On the complex dynamics of birational surface maps defined over number fields
Mattias Jonsson,Paul Reschke
Mathematics , 2015,
Abstract: We show that any birational selfmap of a complex projective surface that has dynamical degree greater than one and is defined over a number field automatically satisfies the Bedford-Diller energy condition after a suitable birational conjugacy. As a consequence, the complex dynamics of the map is well-behaved. We also show that there is a well-defined canonical height function.
Cohomological conditions on endomorphisms of projective varieties
Holly Krieger,Paul Reschke
Mathematics , 2015,
Abstract: We characterize possible periodic subvarieties for surjective endomorphisms of complex abelian varieties in terms of the eigenvalues of the cohomological actions induced by the endomorphisms, extending previous work in this direction by Pink and Roessler. By applying our characterization to induced endomorphisms on Albanese varieties, we draw conclusions about the dynamics of surjective endomorphisms for a broad class of projective varieties. We also analyze several classes of surjective endomorphisms that are distinguished by properties of their cohomological actions.
Lower Semi-Continuity of Entropy in a Family of K3 Surface Automorphisms
Paul Reschke,Bar Roytman
Mathematics , 2015,
Abstract: We compute entropies in a large family of K3 surface automorphisms in (P^1)^3. In keeping with a result by Xie, we find that the entropies vary in a lower semi-continuous manner as the Picard ranks of the K3 surfaces vary.
Experience of cumulative effects assessment in the UK
Piper Jake
Spatium , 2004, DOI: 10.2298/spat0410041p
Abstract: Cumulative effects assessment (CEA) is a development of environmental impact assessment which attempts to take into account the wider picture of what impacts may affect the environment as a result of either multiple or linear projects, or development plans. CEA is seen as a further valuable tool in promoting sustainable development. The broader canvas upon which the assessment is made leads to a suite of issues such as complexity in methods and assessment of significance, the desirability of co-operation between developers and other parties, new ways of addressing mitigation and monitoring. After outlining the legislative position and the process of CEA, this paper looks at three cases studies in the UK where cumulative assessment has been carried out - the cases concern wind farms, major infrastructure and off-shore developments.
Lessons from a Pluralist Approach to a Wicked Policy Issue
Jake Chapman
Integral Review , 2010,
Abstract: The most difficult policy issues are those where there are profound disagreements about what is wrong, what should be done, and how things work. This paper describes a pluralist approach, based on the soft systems methodology, to youth nuisance on deprived estates in Manchester, UK, where there were profound disagreements between the agencies involved. When there are disagreements about the nature of the problem, its causes, or about how the system of interest actually functioned, a pluralist approach is required, and this is provided by Checkland’s soft systems approach. When the disagreements involve conflicts of value, it is necessary to adopt an adaptive approach that fosters change in the values, beliefs or behaviour of those involved. In the spectrum of public sector agencies involved, five different perspectives of agencies were identified, their descriptions indicating the need for the pluralist approach taken. The project was an experiment in using systemic approaches in public policy and the paper describes the learning associated with impacting outcomes. Processes used in the project included a “soft systems” workshop, which is described along with some effects on both the project participants and overall outcomes. The overall aim is to share the experience of this project so that it may inform those working with systemic approaches and other pluralist methods on wicked problems in the public sector.
Comunicación intergeneracional entre extra os y entre miembros de la familia
Jake Harwood
Revista Latinoamericana de Psicología , 2002,
Abstract: Este artículo revisa investigaciones que han examinado la comunicación intergeneracional en dos áreas diferentes. En primer lugar, numerosas investigaciones han analizado la comunicación entre adultos jóvenes y mayores, extra os entre sí. Dicho trabajo se ha centrado, con frecuencia, en procesos por los cuales se forman estereotipos, así como en la "comunicación protectora", y en otras características discursivas de la interacción entre generaciones. En segundo lugar, investigaciones recientes han comenzado a examinar elementos relacionales en las conversaciones, intergeneracionales, analizando, sobre todo, la relación entre abuelos y nietos. Este trabajo se describirá dentro del contexto de modelos teóricos tales como el modelo del predicamento comunicacional en el envejecimiento y la teoría comunicacional de la acomodación.
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