Stony Brook University

About: Stony Brook University is a education organization based out in Stony Brook, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 32534 authors who have published 68218 publications receiving 3035131 citations. The organization is also known as: State University of New York at Stony Brook & SUNY Stony Brook.

The roaming atom: straying from the reaction path in formaldehyde decomposition

Abstract: We present a combined experimental and theoretical investigation of formaldehyde (H2CO) dissociation to H2 and CO at energies just above the threshold for competing H elimination. High-resolution state-resolved imaging measurements of the CO velocity distributions reveal two dissociation pathways. The first proceeds through a well-established transition state to produce rotationally excited CO and vibrationally cold H2. The second dissociation pathway yields rotationally cold CO in conjunction with highly vibrationally excited H2. Quasi-classical trajectory calculations performed on a global potential energy surface for H2CO suggest that this second channel represents an intramolecular hydrogen abstraction mechanism: One hydrogen atom explores large regions of the potential energy surface before bonding with the second H atom, bypassing the saddle point entirely.

Latrunculins--novel marine macrolides that disrupt microfilament organization and affect cell growth: I. Comparison with cytochalasin D.

Abstract: The latrunculins are architecturally novel marine compounds isolated from the Red Sea sponge Latrunculia magnifica. In vivo, they alter cell shape, disrupt microfilament organization, and inhibit the microfilament-mediated processes of fertilization and early development. In vitro, latrunculin A was recently found to affect the polymerization of pure actin in a manner consistent with the formation of a 1:1 molar complex with G-actin. These in vitro effects as well as previous indications that the latrunculins are more potent than the cytochalasins suggest differences in the in vivo mode of action of the two clases of drugs. To elucidate these differences we have compared the short- and long-term effects of latrunculins on cell shape and actin organization to those of cytochalasin D. Exposure of hamster fibroblast NIL8 cells for 1–3 hr to latrunculin A, latrunculin B, and cytochalasin D causes concentration-dependent changes in cell shape and actin organization. However, the latrunculin-induced changes were strikingly different from those induced by cytochalasin D. Furthermore, while initial effects were manifest with both latrunculin A and cytochalasin D already at concentrations of about 0.03 μg/ml, latrunculin A caused complete rounding up of all cells at 0.2 μg/ml, whereas with cytochalasin D maximum contraction was reached at concentrations 10–20 times higher. The short-term effects of latrunculin B were similar to those of latrunculin A although latrunculin B was slightly less potent. All three drugs inhibited cytokinesis in synchronized cells, but their long-term effects were markedly different. NIL8 cells treated with latrunculin A maintained their altered state for extended periods. In contrast, the effects of cytochalasin D progressed with time in culture, and the latrunculin B-induced changes were transient in the continued presence of the drug. These transient effects were found to be due to a gradual inactivation of latrunculin B by serum and were used to compare recovery patterns of cell shape and actin organization in two different cell lines. This comparison showed that the transient effects of latrunculin B were fully reversible for the NIL8 cells and not for the mouse neuroblastoma N1E-115 cells.

J-Holomorphic Curves and Quantum Cohomology

Abstract: Introduction Local behaviour Moduli spaces and transversality Compactness Compactification of moduli spaces Evaluation maps and transversality Gromov-Witten invariants Quantum cohomology Novikov rings and Calabi-Yau manifolds Floer homology Gluing Elliptic regularity Bibliography Indexes.

The CO-to-H2 Conversion Factor and Dust-to-gas Ratio on Kiloparsec Scales in Nearby Galaxies

Abstract: We present ~{}kiloparsec spatial resolution maps of the CO-to-H$_{2}$ conversion factor ({$α$}$_{CO}$) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for {$α$}$_{CO}$ and the DGR by assuming that the DGR is approximately constant on kiloparsec scales. With this assumption, we can combine maps of dust mass surface density, CO-integrated intensity, and H I column density to solve for both {$α$}$_{CO}$ and the DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high-resolution far-IR maps from the Herschel key program KINGFISH, $^{12}$CO J = (2-1) maps from the IRAM 30 m large program HERACLES, and H I 21 cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our {$α$}$_{CO}$ results on the more typically used $^{12}$CO J = (1-0) scale and show using literature measurements that variations in the line ratio do not affect our results. In total, we derive 782 individual solutions for {$α$}$_{CO}$ and the DGR. On average, {$α$}$_{CO}$ = 3.1 M $_{☉}$ pc$^{–2}$ (K km s$^{–1}$)$^{–1}$ for our sample with a standard deviation of 0.3 dex. Within galaxies, we observe a generally flat profile of {$α$}$_{CO}$ as a function of galactocentric radius. However, most galaxies exhibit a lower {$α$}$_{CO}$ value in the central kiloparsec{mdash}a factor of ~{}2 below the galaxy mean, on average. In some cases, the central {$α$}$_{CO}$ value can be factors of 5-10 below the standard Milky Way (MW) value of {$α$}$_{CO, MW}$ = 4.4 M $_{☉}$ pc$^{–2}$ (K km s$^{–1}$)$^{–1}$. While for {$α$}$_{CO}$ we find only weak correlations with metallicity, the DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate {$α$}$_{CO}$ for studies of nearby galaxies.

Integrative functional genomic analysis of human brain development and neuropsychiatric risks

Abstract: To broaden our understanding of human neurodevelopment, we profiled transcriptomic and epigenomic landscapes across brain regions and/or cell types for the entire span of prenatal and postnatal development. Integrative analysis revealed temporal, regional, sex, and cell type-specific dynamics. We observed a global transcriptomic cup-shaped pattern, characterized by a late fetal transition associated with sharply decreased regional differences and changes in cellular composition and maturation, followed by a reversal in childhood-adolescence, and accompanied by epigenomic reorganizations. Analysis of gene coexpression modules revealed relationships with epigenomic regulation and neurodevelopmental processes. Genes with genetic associations to brain-based traits and neuropsychiatric disorders (including MEF2C, SATB2, SOX5, TCF4, and TSHZ3) converged in a small number of modules and distinct cell types, revealing insights into neurodevelopment and the genomic basis of neuropsychiatric risks.