27,802 research outputs found
Symplectic torus bundles and group extensions
Symplectic torus bundles are classified by the second
cohomology group of with local coefficients . For a
compact, orientable surface, the main theorem of this paper gives a necessary
and sufficient condition on the cohomology class corresponding to for
to admit a symplectic structure compatible with the symplectic bundle structure
of : namely, that it be a torsion class. The proof is based on a
group-extension-theoretic construction of J. Huebschmann (Sur les premieres
differentielles de la suite spectrale cohomologique d'une extension de groupes,
C.R. Acad. Sc. Paris, Serie A, tome 285, 28 novembre 1977, 929-931). A key
ingredient is the notion of fibrewise-localization.Comment: 18 page
Kant’s theory of conscience
In this paper I discuss Kant’s theory of conscience. In particular, I explicate the following two claims that Kant makes in the Metaphysics of Morals: (1) an erring conscience is an absurdity and (2) if an agent has acted according to his/her conscience, then s/he has done all that can be required of him/her. I argue that (1) is a very specific claim that does not bear on the problem of moral knowledge. I argue that (2) rests on a strongly internalist line of argument
California Voting and Suburbanization Patterns: Implications for Transit Policy, MTI Report 12-05
Public transit is an environmentally friendly transportation mode that usually focuses on transporting people within and to the city center. However, over the last 60 years, population and employment has been suburbanizing. As the median voter lives further from the city center, and thus enjoys fewer benefits from accessing public transit, does this reduce such a voter’s propensity to support public investment in public transit improvements? We analyze voting patterns on 20 transit-related ballot propositions from state-wide elections in California between 1990 and 2010. Controlling for demographic, socio-economic and political ideological factors, we focus on the role of suburbanization as a possible causal factor in determining public support for public transit investment. The results provide a rich picture of the attitudes towards transportation policy among California voters, and will help policy makers to better understand citizen preferences and to better predict how future trends will shift support towards or against transit. Finally, we suggest ways policy makers can use urban land markets to increase support for trans
The Impact of Center City Economic and Cultural Vibrancy on Greenhouse Gas Emissions from Transportation, Research Report 11-13
Urban planners and scholars have focused a great deal of attention on understanding the relationship between the built environment and transportation behavior. However, other aspects of the urban environment – including the vibrancy and quality of life in urban areas – have received little attention. This report seeks to close this gap by analyzing the effects of both land-use and urban vibrancy on transportation patterns. Analysis of data from a variety of sources suggests that in addition to the built-environment, the vibrancy of the urban environment also affects transportation behavior. Moreover, vibrancy affects land-use patterns. By integrating objective measures of center-city quality of life into transportation choice models, our new statistical results inform public policy. We discuss specific public policy options for reducing greenhouse gas emissions and increasing public transit use
Proof of a conjecture of N. Konno for the 1D contact process
Consider the one-dimensional contact process. About ten years ago, N. Konno
stated the conjecture that, for all positive integers , the upper
invariant measure has the following property: Conditioned on the event that
is infected, the events All sites are healthy and All
sites are healthy are negatively correlated. We prove (a stronger
version of) this conjecture, and explain that in some sense it is a dual
version of the planar case of one of our results in \citeBHK.Comment: Published at http://dx.doi.org/10.1214/074921706000000031 in the IMS
Lecture Notes--Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
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