State University of New York System

About: State University of New York System is a education organization based out in Albany, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 54077 authors who have published 78070 publications receiving 2985160 citations.

Synchrotron computed microtomography of porous media: Topology and transports.

Abstract: Computed microtomography is applied to a piece of Fontainebleau sandstone in order to determine the geometrical structure of the pores. The topology of the void space is then derived from the tomographic image of the volume. Permeability and conductivity are computed and found in good agreement with experimental data. Perspectives offered by this new nondestructive method with a potential resolution of the order of one micrometer or less are analyzed.

A boundary value problem associated with the second painlevé transcendent and the Korteweg-de Vries equation

Abstract: The differential equation considered is \(y'' - xy = y|y|^\alpha \). For general positive α this equation arises in plasma physics, in work of De Boer & Ludford. For α=2, it yields similarity solutions to the well-known Korteweg-de Vries equation. Solutions are sought which satisfy the boundary conditions (1) y(∞)=0 (2) $$y{\text{(}}\infty {\text{)}} = {\text{0}}$$ (1) $$y{\text{(}}x{\text{) \~( - }}\tfrac{{\text{1}}}{{\text{2}}}x{\text{)}}^{{{\text{1}} \mathord{\left/ {\vphantom {{\text{1}} \alpha }} \right. \kern- ulldelimiterspace} \alpha }} {\text{ as }}x \to - \infty $$ (2) It is shown that there is a unique such solution, and that it is, in a certain sense, the boundary between solutions which exist on the whole real line and solutions which, while tending to zero at plus infinity, blow up at a finite x. More precisely, any solution satisfying (1) is asymptotic at plus infinity to some multiple kA i(x) of Airy's function. We show that there is a unique k*(α) such that when k=k*(α) the condition (2) is also satisfied. If 0 k* then the solution blows up at a finite x. For the special case α=2 the differential equation is classical, having been studied by Painleve around the turn of the century. In this case, using an integral equation derived by inverse scattering techniques by Ablowitz & Segur, we are able to show that k*=1, confirming previous numerical estimates.

Comparing self-reported and physician-reported medical history.

Abstract: The authors compared self-reported medical history and medication use in a cataract case-control study of 1,380 persons (1985-1989) in Boston, Massachusetts, with information from the participants' physicians. Under- and overreporting varied by condition and type of medication. A self-reported history of hypertension had the highest sensitivity (91%), and diabetes history had the highest specificity (97%). Among different medications investigated, self-reported antihypertensive medication use was the most sensitive (88%), while self-reported use of insulin was the most specific (99%). Differences between patient- and physician-reported frequencies were very small, except for arthritis (15%) and regular aspirin use (21%). Results suggest an accurate recall of medical and drug usage history in well-defined chronic conditions.

Persistent activation of the zeta isoform of protein kinase C in the maintenance of long-term potentiation

Abstract: Long-term potentiation in the CA1 region of the hippocampus, a model for memory formation in the brain, is divided into two phases. A transient process (induction) is initiated, which then generates a persistent mechanism (maintenance) for enhancing synaptic strength. Protein kinase C (PKC), a gene family of multiple isozymes, may play a role in both induction and maintenance. In region CA1 from rat hippocampal slices, most of the isozymes of PKC translocated to the particulate fraction 15 sec after a tetanus. The increase of PKC in the particulate fraction did not persist into the maintenance phase of long-term potentiation. In contrast, a constitutively active kinase, PKM, a form specific to a single isozyme (zeta), increased in the cytosol during the maintenance phase. The transition from translocation of PKC to formation of PKM may help to explain the molecular mechanisms of induction and maintenance of long-term potentiation.