Toward a Quantization of Null Dust Collapse

Spherically symmetric, null dust clouds, like their time-like counterparts, may collapse classically into black holes or naked singularities depending on their initial conditions. We consider the Hamiltonian dynamics of the collapse of an arbitrary distribution of null dust, expressed in terms of the physical radius, $R$, the null coordinates, $V$ for a collapsing cloud or $U$ for an expanding cloud, the mass function, $m$, of the null matter, and their conjugate momenta. This description is obtained from the ADM description by a Kucha\v{r}-type canonical transformation. The constraints are linear in the canonical momenta and Dirac's constraint quantization program is implemented. Explicit solutions the constraints are obtained for both expanding and contracting null dust clouds with arbitrary mass functions.Comment: 10 pages, 2 figures (eps), RevTeX4. The last two sections have been revised and corrected. To appear in Phys. Rev.

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Photo-oxidative stress in coconut seedlings: early events to leaf scorching and seedling death

Peer Editor: Angela Senne; Faculty Mentor: Carl Craver The case of Franz Breundl, a man who suffered from anterograde amnesia and a severe impairment of working memory is discussed in this work. After exposure to carbon monoxide fumes, Breundl could remember nothing for more than two seconds – a condition that is, as far we know, unprecedented in the literature. Gustav Störring and Ernst Grünthal originally documented the case in 1931, and the ensuing debate about its authenticity among German academics lasted nearly three decades. Since then, the case has been largely forgotten. Here, Breundl’s condition is reevaluated in light of our current understanding of short-term memory and attentional disorders and a tentative diagnosis of a deficit in the central executive capacities of working memory is offered. From the Washington University Undergraduate Research Digest: WUURD, Volume 6, Issue 2, Spring 2011. Published by the Office of Undergraduate Research, Joy Zalis Kiefer Director of Undergraduate Research and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Editor