Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

The mobility and diffusion of ions in gases

Abstract: Experimental and theoretical aspects of the mobility and diffusion of ions in gases are studied in detail. Some of the subjects discussed include ion-ion interaction, boundary condition and ion and electron behavior. Also discussed in separate chapters are the problems of the diffusion coefficients and the afterglow techniques. Finally, a special chapter studies the kinetic theory of diffusion and mobility, stressing the low-, medium- and high-field theory.

Central projections of melanopsin-expressing retinal ganglion cells in the mouse

Abstract: A rare type of ganglion cell in mammalian retina is directly photosensitive. These novel retinal photoreceptors express the photopigment melanopsin. They send axons directly to the suprachiasmatic nucleus (SCN), intergeniculate leaflet (IGL), and olivary pretectal nucleus (OPN), thereby contributing to photic synchronization of circadian rhythms and the pupillary light reflex. Here, we sought to characterize more fully the projections of these cells to the brain. By targeting tau-lacZ to the melanopsin gene locus in mice, ganglion cells that would normally express melanopsin were induced to express, instead, the marker enzyme beta-galactosidase. Their axons were visualized by X-gal histochemistry or anti-beta-galactosidase immunofluorescence. Established targets were confirmed, including the SCN, IGL, OPN, ventral division of the lateral geniculate nucleus (LGv), and preoptic area, but the overall projections were more widespread than previously recognized. Targets included the lateral nucleus, peri-supraoptic nucleus, and subparaventricular zone of the hypothalamus, medial amygdala, margin of the lateral habenula, posterior limitans nucleus, superior colliculus, and periaqueductal gray. There were also weak projections to the margins of the dorsal lateral geniculate nucleus. Co-staining with the cholera toxin B subunit to label all retinal afferents showed that melanopsin ganglion cells provide most of the retinal input to the SCN, IGL, and lateral habenula and much of that to the OPN, but that other ganglion cells do contribute at least some retinal input to these targets. Staining patterns after monocular enucleation revealed that the projections of these cells are overwhelmingly crossed except for the projection to the SCN, which is bilaterally symmetrical.

Ecological and evolutionary insights from species invasions

Abstract: Species invasions provide numerous unplanned and frequently, but imperfectly, replicated experiments that can be used to better understand the natural world. Classic studies by Darwin, Grinnell, Elton and others on these species-invasion experiments provided invaluable insights for ecology and evolutionary biology. Recent studies of invasions have resulted in additional insights, six of which we discuss here; these insights highlight the utility of using exotic species as 'model organisms'. We also discuss a nascent hypothesis that might provide a more general, predictive understanding of invasions and community assembly. Finally, we emphasize how the study of invasions can help to inform our understanding of applied problems, such as extinction, ecosystem function and the response of species to climate change.

Time to recovery, chronicity, and levels of psychopathology in major depression. A 5-year prospective follow-up of 431 subjects

Abstract: • The course of illness of 431 subjects with major depression participating in the National Institute of Mental Health Collaborative Depression Study was prospectively observed for 5 years. Twelve percent of the subjects still had not recovered by 5 years. There were decreasing rates of recovery over time. For example, 50% of the subjects recovered within the first 6 months, and then the rate of recovery declined markedly. Instantaneous probabilities of recovery reflect that the longer a patient was ill, the lower his or her chances were of recovering. For patients still depressed, the likelihood of recovery within the next month declined from 15% during the first 3 months of follow-up to 1 % to 2% per month during years 3, 4, and 5 of this follow-up. The severity of current psychopathology predicted the probability of subsequent recovery. Subjects with moderately severe depressive symptoms, minor depression, or dysthymia had an 18-fold greater likelihood of beginning recovery within the next week than did subjects who were at full criteria for major depressive disorder. Many subjects who did not recover continued in an episode that looked more like dysthymia than major depressive disorder.

Channels of Interstate Risk Sharing: United States 1963–1990

Abstract: We develop a framework for quantifying the amount of risk sharing among states in the United States, and construct data that allow us to decompose the cross-sectional variance in gross state product into several components which we refer to as levels of smoothing. We find that 39 percent of shocks to gross state product are smoothed by capital markets, 13 percent are smoothed by the federal government, and 23 percent are smoothed by credit markets. The remaining 25 percent are not smoothed. We also decompose the federal government smoothing into subcategories: taxes, transfers, and grants to states.