946 research outputs found

    The role of norepinephrine in spatial reference and spatial working memory

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    The adrenergic system (utilizing norepinephrine, NE, as a neurotransmitter) is implicated in hippocampus-based learning and memory, in addition to its well known peripheral actions mediated by the sympathetic nervous system. We have produced a strain of mice in which the gene coding for the enzyme dopamine beta-hydroxylase (Dbh), which catalyzes the synthesis of NE from dopamine, has been disrupted. Mice recessive (Dbh-/-) for the Dbh gene mutation lack endogenous NE and epinephrine, while heterozygous mice (Dbh+/-) have normal levels of NE and epinephrine and display normal phenotype. Previous studies have indicated that NE is necessary and sufficient for the retrieval of intermediate-term contextual and spatial memories, but is not necessary for the retrieval or consolidation of emotional memories in general (Thomas et al. 1996). We tested whether this relationship would stand for memories that were appetitive rather than aversive. We tested 20 Dbh-/- and 20 Dbh+/- mice in an eight-arm radial maze. We found no difference between KOs and controls in ability to recall spatial cues 24 hours after training. This negative result indicated that NE may not be critical for retrieval of all hippocampus-dependent memories but specifically those that are aversive. Using a more standard variation of the above protocol on the radial arm maze, we used this apparatus to test the role of NE in spatial working memory. We found significant, robust differences between Dbh-/- and Dbh+/- mice after a training period of approximately 14 days. To test whether this difference was due to a potential deficit in acquisition or performance, we restored NE in Dbh-/- mice by administering the synthetic precursor L-DOPS after four days of stable behavioral differences between genotypes. In a separate trial, we also restored NE signaling with dexmedetomidine, a selective alpha-2 receptor agonist. A gradual improvement by Dbh-/- mice to levels comparable to Dbh+/- mice indicated that NE is critical for the acquisition of spatial working memory, and suggested a role for the alpha-2 adrenergic receptor in the processing of spatial working memory

    Petro fabric characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif)

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    This paper presents results of study of petro fabric specific characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif

    Sedimentary deposits and petrography of the basalts of the island of Tenerife of the Canary archipelago (Spain)

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    The article is devoted to the study of sedimentary deposits on the slopes of the Teide volcano and petrography of the volcanic rocks of the island of Tenerife of the Canary archipelago (Spain). A description of the sediments, which are presented on the island's territory, and an analysis of the features of the material composition of rocks are given

    Set in Stone: Building America's New Generation of Arts Facilities, 1994-2008

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    In 2007, just before the domestic economy experienced a major trauma, the Cultural Policy Center at the Harris School and NORC at the University of Chicago launched a national study of cultural building in the United States. It was motivated by multiple requests from leading consultants in the cultural sector who found themselves involved in a steadily growing number of major building projects -- museums, performing arts centers (PACs), and theaters -- and from foundation officers who were frequently asked to help fund these infrastructure projects. With the generous support of the Andrew W. Mellon Foundation, the Kresge Foundation, and the John D. and Catherine T. MacArthur Foundation, we were able to conduct systematic scientific research on cultural building in the United States between 1994 and 2008 and come to a number of conclusions that have important implications for the cultural sector

    Features of geology and composition of rocks from the alkaline-gabbroid University massif (NE Kuznetsk Alatau ridge, Siberia)

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    This paper discusses specifics of petrography and structural tectonic position of the alkaline-gabbroic University massif, which is a sort of analogue of the Kiya-Shaltyr deposit of nepheline ores in this area that was very slightly eroded. In this work, we will also present new precise analytical data on rare and trace element distribution in major intrusive phases of this geological object, and also isotope dating on the basis of Sm-Nd method

    Features of geology and composition of rocks from the alkaline-gabbroic University massif (N-E Kuznetsky Alatau ridge, Siberia)

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    This paper discusses specifics of petrography and structural tectonic position of the alkaline-gabbroic University massif, which is a sort of analogue of the Kiya-Shaltyr deposit of nepheline ores in this area that was very slightly eroded. In this work, we will also present new precise analytical data on rare and trace element distribution in major intrusive phases of this geological object, and also isotope dating on the basis of method Sm-Nd

    The Barkhatny ultramafic-mafic massif (Kuznetsk Alatau Ridge, SW Siberia): structural and compositional evolutions of rocks

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    A complex of petrographic and petrofabric analyses that was carried out for rocks from an ultramafic-mafic massif of the Barkhatnaya Mountain in the Northern part of the Kuznetsk Alatau allowed us to prove that internal anisotropy of mineral aggregates had deformation-type evolution, which indicates possible plastic exhumation of lithosphere mantle fragments into upper crust levels. Additional mineralogical and geochemical researches of the basic component point out high possibility of multistage model for obduction of ophiolite association segments proposed for this region

    Geological structure and prospects of noble metal ore mineralization of the Khayrkhan gabbroid massif (Western Mongolia)

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    An analysis of the distribution of noble metals in zones of sulfide mineralization makes it possible to justify the isolation of four ore-bearing horizons with a specific geochemical zonation. A rise in the gold content relative to palladium and platinum is observed from the bottom upwards along the section of the stratified series of gabbroids. The study of the mineral phases of sulphides and the noble minerals itself indicates the evolution of hydrothermal solutions, which determines the different activity and mobility of the fluid (mercury, tellurium, sulfur) and ore (copper, nickel, iron, platinum, gold and silver) components
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