Carleton University

About: Carleton University is a education organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 15852 authors who have published 39650 publications receiving 1106610 citations.

Disruption of cocaine self-administration following 6-hydroxydopamine lesions of the ventral tegmental area in rats

Abstract: 6-Hydroxydopamine-induced destruction of dopaminergic terminals in the nucleus accumbens have been shown previously to disrupt cocaine and amphetamine self-administration. We sought to determine whether lesions of the DA cell bodies in the ventral tegmental area (VTA) which give rise to the DA innervation of the n. accumbens, would also disrupt cocaine self-administration behavior. Rats were trained to self-inject cocaine (0.75 mg/kg) for 4 hr/day. After a stable baseline was established, one group of rats received bilateral injections of 6-OHDA (4 micrograms/l microliter) into the VTA. Control rats received vehicle injections. When retested on the fifth day post-lesion, all of the 6-OHDA treated animals showed a long lasting reduction in cocaine intake. Three animals did not reinitiate cocaine self-administration after the lesion, although each showed stable post-lesion responding for apomorphine. The surgery had no effect on cocaine self-administration in control animals. These data support the hypothesis that dopaminergic mechanisms are necessary for the normal expression of cocaine self-administration.

Time-varying graphs and dynamic networks

Abstract: The past few years have seen intensive research efforts carried out in some apparently unrelated areas of dynamic systems – delay-tolerant networks, opportunistic-mobility networks and social networks – obtaining closely related insights. Indeed, the concepts discovered in these investigations can be viewed as parts of the same conceptual universe, and the formal models proposed so far to express some specific concepts are the components of a larger formal description of this universe. The main contribution of this paper is to integrate the vast collection of concepts, formalisms and results found in the literature into a unified framework, which we call time-varying graphs TVGs. Using this framework, it is possible to express directly in the same formalism not only the concepts common to all those different areas, but also those specific to each. Based on this definitional work, employing both existing results and original observations, we present a hierarchical classification of TVGs; each class corresponds to a significant property examined in the distributed computing literature. We then examine how TVGs can be used to study the evolution of network properties, and propose different techniques, depending on whether the indicators for these properties are atemporal as in the majority of existing studies or temporal. Finally, we briefly discuss the introduction of randomness in TVGs.

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

Abstract: This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.

Independent effects of forest cover and fragmentation on the distribution of forest breeding birds

Abstract: The aims of this study were (1) to determine the relative importance of the independent effects of forest cover and fragmentation on the distribution of forest breeding birds, and (2) to test the hypothesis that the negative effect of forest fragmentation on species distribution increases with decreasing forest cover, i.e., the negative interaction effect of forest cover and fragmentation on distribution. The independent effects of forest cover and forest fragmentation on the distribution of forest breeding birds were studied in 94 landscapes, 10 × 10 km each, ranging in forest cover from 2.5% to 55.8%. For each landscape, percent forest cover was measured, and a fragmentation index (independent of forest cover) was generated using PCA from the measures of mean forest patch size, number of forest patches, and total forest edge. Presence of 31 forest breeding bird species in each landscape was determined using Breeding Bird Atlas data. The effects of forest cover and forest fragmentation on species presenc...