The coastal environmental profile of Ban Don Bay and Phangnga Bay, Thailand

Environmental profile, Coastal zone management, Coastal zone, Ban Don Bay, Phangnga Bay, Thailand, Environmental Economics and Policy,

Room temperature electron spin relaxation in GaInNAs multiple quantum wells at 1.3 mu m

The authors report a direct measurement of electron spin relaxation in GaInNAs semiconductor multiple quantum wells at room temperature. Multiple quantum wells of widths 5.8, 7, and 8 nm exhibiting excitonic absorption around 1.3 mu m have been studied. Spin relaxation times were found to increase with well width in the range of 77-133 ps. The spin relaxation time dependence on first electron confinement energy suggests the Elliot-Yafet mechanism [A. Tackeuchi , Physica B 272, 318 (1999)] as the dominant relaxation process. (c) 2006 American Institute of Physics.</p

Kadison-Kastler stable factors

A conjecture of Kadison and Kastler from 1972 asks whether sufficiently close operator algebras in a natural uniform sense must be small unitary perturbations of one another. For n≥3 and a free, ergodic, probability measure-preserving action of SL&lt;sub&gt;n&lt;/sub&gt;(Z) on a standard nonatomic probability space (X,μ), write M=(L&lt;sup&gt;∞&lt;/sup&gt;(X,μ)⋊SL&lt;sub&gt;n&lt;/sub&gt;(Z))⊗¯¯¯R, where R is the hyperfinite II1-factor. We show that whenever M is represented as a von Neumann algebra on some Hilbert space H and N⊆B(H) is sufficiently close to M, then there is a unitary u on H close to the identity operator with uMu∗=N. This provides the first nonamenable class of von Neumann algebras satisfying Kadison and Kastler’s conjecture. We also obtain stability results for crossed products L&lt;sup&gt;∞&lt;/sup&gt;(X,μ)⋊Γ whenever the comparison map from the bounded to usual group cohomology vanishes in degree 2 for the module L&lt;sup&gt;2&lt;/sup&gt;(X,μ). In this case, any von Neumann algebra sufficiently close to such a crossed product is necessarily isomorphic to it. In particular, this result applies when Γ is a free group

A remark on the similarity and perturbation problems

In this note we show that Kadison's similarity problem for C*-algebras is equivalent to a problem in perturbation theory: must close C*-algebras have close commutants?Comment: 6 Pages, minor typos fixed. C. R. Acad. Sci. Canada, to appea

Persistence and Memory in Patchwork Dynamics for Glassy Models

Slow dynamics in disordered materials prohibits direct simulation of their rich nonequilibrium behavior at large scales. "Patchwork dynamics" is introduced to mimic relaxation over a very broad range of time scales by equilibrating or optimizing directly on successive length scales. This dynamics is used to study coarsening and to replicate memory effects for spin glasses and random ferromagnets. It is also used to find, with high confidence, exact ground states in large or toroidal samples.Comment: 4 pages, 4 figures; reference correctio

Credit and Human Welfare: Lessons from Microcredit in Developing Nations

Deregulation of usury laws, in the United States and in developing nations, has permitted various forms of small loans to be made to the poor and the working class, sometimes at very high prices. In the case of credit, more is not always better. A human development approach to evaluating the welfare impacts of credit products for the poor asks these questions: does a credit product or program increase income or consumption, achieve savings through investment in capital goods, or smooth consumption and avert crises, all at a reasonable cost? Or does the credit on balance redistribute income away from the poor, without adequate offsetting benefits, or produce overindebtedness and declining borrower living standards? The model of successful small-loan programs that may enhance the welfare of the poor is the work of the Grameen Bank in Bangladesh. Grameen Bank’s microlending, savings, and insurance programs seem to have been effective in improving the lives of some Grameen borrowers. On the other hand, the experiences of South Africa and Bolivia with rapid expansion of microcredit were more problematic, resulting in crises of overindebtedness and, in the case of Bolivia, a social revolt by borrowers. Even after the crisis in Bolivia, however, some microlenders and their borrowers fared better. The experiences in these different contexts, as well as the United States’ experience with payday lending, offer important insights into the benefits and risks of different credit products and programs for the poor. These insights can inform the next generation of consumer credit regulation, which should promote responsible lending based on full credit reporting, insurance, workouts to protect against and mitigate defaults, continual repayment of principal, differentiation based on credit use, and simple and transparent pricing