656 research outputs found
The thalamic reticular nucleus: a functional hub for thalamocortical network dysfunction in schizophrenia and a target for drug discovery
The thalamus (comprising many distinct nuclei) plays a key role in facilitating sensory discrimination and cognitive processes through connections with the cortex. Impaired thalamocortical processing has long been considered to be involved in schizophrenia. In this review we focus on the thalamic reticular nucleus (TRN) providing evidence for it being an important communication hub between the thalamus and cortex and how it may play a key role in the pathophysiology of schizophrenia. We first highlight the functional neuroanatomy, neurotransmitter localisation and physiology of the TRN. We then present evidence of the physiological roles of the TRN in relation to oscillatory activity, cognition and behaviour. Next we discuss the role of the TRN in rodent models of risk factors for schizophrenia (genetic and pharmacological) and provide evidence for TRN deficits in schizophrenia. Finally we discuss new drug targets for schizophrenia in relation to restoring TRN circuitry dysfunction
The Perseverance of Neoliberalism: Why Obama Has Not Shifted Trade Policy in Response to the Great Recession
This thesis examines Obama’s reasons for not shifting trade during the recession. The author goes into depth about how business groups influence Obama and his decisions on trade policies. Obama’s and Clinton’s administrations and their policies, through documents, speeches, and other sources, are also compared due to the fact that Clinton was the last Democratic president. Scholarly literature is also examined in regards to both Clinton’s and Obama’s presidency
Alterations in functional brain network structure induced by subchronic phencyclidine (PCP) treatment parallel those seen in schizophrenia
Abstract of poster presentation shown at the 2nd Biennial Schizophrenia International Research Conference on Alterations in functional brain network structure induced by subchronic phencyclidine (PCP) treatment parallel those seen in schizophrenia
An appropriate level of risk: Balancing the need for safe livestock products with fair market access for the poor
This paper examines the role of livestock products as commodities of trade, responding to the demand and higher prices that many external markets offer, and at the same time providing important contributions to the development process in poorer countries. It highlights that this opportunity is not without its threats: much of the Western world has, over the last half century in particular, invested substantial amounts of money in controlling and eradicating many infectious diseases of livestock, and in building up healthy and highly productive animals, the products derived from which earn them very large sums of money on world markets. Such countries are not willing to take risks that could threaten their livestock industries, and their domestic and export markets that maintain high animal health and food safety standards. The study builds on a number of 'success stories', examples where developing countries have succeeded in exporting livestock or livestock products to external markets. An analysis of the factors governing their success revealed some commonalities: all were driven by strong private sector partners who contributed capital, management expertise and entrepreneurial flair; most concerned livestock products, rather than live animals, which matched the market's requirements; many had developed strong brand identities which had become synonymous with quality, safety and dependability; and many were vertically integrated systems, incorporating small and medium scale out-grower producers. Often these successes have been achieved despite the absence of effective support from the public sector, such as national veterinary authorities. One of the key findings of this study is the disparity between the push for global harmonisation of animal health standards for trade, and the lack of capacity of developing countries, particularly LDCs, to meet these standards. The study considers how this might be rectified and concludes that building capacity of regional bodies to create regional centres of excellence with regard to SPS matters may be the most practical way forward.Livestock Production/Industries,
Coprolites in the Ravens Throat River Lagerstätte of northwestern Canada: implications for the middle Cambrian food web
The Rockslide Formation (middle Cambrian, Drumian,
Bolaspidella Zone) of the Mackenzie Mountains, northwestern Canada, hosts the
Ravens Throat River Lagerstätte, which consists of two, 1-m thick intervals of
greenish, thinly laminated, locally burrowed, slightly calcareous mudstone yielding a
low-diversity and low-abundance fauna of bivalved arthropods, ‘worms’, hyoliths,
and trilobites. Also present are flattened, circular, black carbonaceous objects
averaging 15 mm in diameter, interpreted as coprolites preserved in either dorsal or
ventral view. Many consist of aggregates of ovate carbonaceous flakes 0.5–2 mm
long, which are probably compacted fecal pellets. Two-thirds contain a variably
disarticulated pair of arthropod valves, and many also contain coiled to fragmented,
corrugated ‘worm’ cuticle, either alone or together with valves. A few contain an
enrolled agnostoid. In rare cases a ptychoparioid cranidium, agnostoid shield,
bradoriid valve, or hyolith conch or operculum is present; these are taken to be due to
capture and ingestion of bioclasts from the adjacent seafloor. Many of the coprolites
are associated with semi-circular spreiten produced by movement of the worm-like
predator while it occupied a vertical burrow. Its identity is unknown but it clearly
exhibited prey selectivity. Many coprolites contain one or more articulated hyoliths,
ptychoparioid trilobites, or outstretched agnostoid arthropods oriented dorsal side up.
These are interpreted as opportunistic coprovores drawn to the organic-rich fecal mass
while it was lodged near the entrance to the burrow. This argues that hyoliths were
mobile detritivores, and agnostoids were mainly nektobenthic or benthic, like the
ptychoparioid trilobites. Fecal matter was probably an important source of nutrition in
the Cambrian food web
Sedimentation, earthquakes, and tsunamis in a shallow, muddy epeiric sea: Grinnell Formation (Belt Supergroup, ca. 1.45 Ga), western North America
Interpreting the deposits of ancient epeiric seas presents unique challenges because of the lack of direct modern analogs. Whereas many such seas were tectonically relatively quiescent, and successions are comparatively thin and punctuated by numerous sedimentary breaks, the Mesoproterozoic Belt Basin of western North America was structurally active and experienced dramatic and continuous subsidence and sediment accumulation. The Grinnell Formation (ca. 1.45 Ga) in the lower part of the Belt Supergroup affords an opportunity to explore the interplay between sedimentation and syndepositional tectonics in a low-energy, lake-like setting. The formation is a thick, vivid, red- to maroon-colored mudstone-dominated unit that crops out in northwestern Montana and adjacent southwestern Alberta, Canada. The mudstone, or argillite, consists of laminated siltstone and claystone, with normal grading, local lowamplitude, short-wavelength symmetrical ripples, and intercalations of thin tabular intraclasts. These intraclasts suggest that the muds acquired a degree of stiffness on the seafloor. Halite crystal molds and casts are present sporadically on bedding surfaces. Beds are pervasively cut by mudcracks exhibiting a wide variety of patterns in plan view, ranging from polygonal to linear to spindle-shaped. These vertical to subvertical cracks are filled with upward-injected mud and small claystone intraclasts. Variably interbedded are individual, bundled, or amalgamated, thin to medium beds of white, cross-laminated, medium- to coarse-grained sandstone, or quartzite. These are composed of rounded quartz grains, typically with subangular to rounded mudstone intraclasts. Either or both the bottoms and tops of sandstone beds commonly show sandstone dikes indicative of downward and upward injection. Both the mudcracks and the sandstone dikes are seismites, the result of mud shrinkage and sediment injection during earthquakes. An origin via passive desiccation or syneresis is not supported, and there is no evidence that the sediments were deposited on alluvial plains, tidal flats, or playas, as has been universally assumed. Rather, deposition occurred in relatively low-energy conditions at the limit of ambient storm wave base. The halite is not from in situ evaporation but precipitated from hypersaline brines that were concentrated in nearshore areas and flowed into the basin causing temporary density stratification. Sandstone beds are not fluvial. Instead, they consist of allochthonous sediment and record a combination of unidirectional and oscillatory currents. The rounded nature of the sand and irregular stratigraphic distribution of the sandstone intervals are explained not by deltaic influx or as tempestites but as coastal sands delivered from the eastern side of the basin by off-surge from episodic tsunamis generated by normal faulting mainly in the basin center. The sands were commonly reworked by subsequent tsunami onrush, off-surge, seiching, and weak storminduced wave action. Although the Grinnell Formation might appear superficially to have the typical hallmarks of a subaerial mudflat deposit, its attributes in detail reveal that sedimentation and deformation took place in an entirely submerged setting. This is relevant for the deposits of other ancient epeiric seas as well as continental shelves, and it should invite reconsideration of comparable successions.Fil: Pratt, Brian. University of Saskatchewan; CanadáFil: Ponce, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentin
Heritage Stone 9. Tyndall Stone, Canada’s First Global Heritage Stone Resource: Geology, Paleontology, Ichnology and Architecture
Tyndall Stone is a distinctively mottled and strikingly fossiliferous dolomitic limestone that has been widely used for over a century in Canada, especially in the Prairie Provinces. It comprises 6–8 m within the lower part of the 43 m thick Selkirk Member of the Red River Formation, of Late Ordovician (Katian) age. It has been quarried exclusively at Garson, Manitoba, 37 km northeast of Winnipeg, since about 1895, and for the past half-century extraction has been carried out solely by Gillis Quarries Ltd. The upper beds tend to be more buff-coloured than the grey lower beds, as a result of groundwater weathering. Tyndall Stone, mostly with a smooth or sawn finish, has been put to a wide variety of uses, including exterior and interior cladding with coursed and random ashlar, and window casements and doorways. Split face finish and random ashlar using varicoloured blocks split along stylolites have become popular for commercial and residential buildings, respectively. Tyndall Stone lends itself to carving as well, being used in columns, coats of arms and sculptures. Many prominent buildings have been constructed using Tyndall Stone, including the provincial legislative buildings of Saskatchewan and Manitoba, the interior of the Centre Block of the House of Commons in Ottawa, courthouses, land titles buildings, post offices and other public buildings, along with train stations, banks, churches, department stores, museums, office buildings and university buildings. These exhibit a variety of architectural styles, from Beaux Arts to Art Deco, Châteauesque to Brutalist. The Canadian Museum of History and the Canadian Museum for Human Rights are two notable Expressionist buildings. The lower Selkirk Member is massive and consists of bioturbated, bioclastic wackestone to packstone, rich in crinoid ossicles. It was deposited in a low-energy marine environment within the photic zone, on the present-day eastern side of the shallow Williston Basin, which was part of the vast equatorial epicontinental sea that covered much of Laurentia at the time. Scattered thin bioclastic grainstone lenses record episodic, higher energy events. Tyndall Stone is spectacularly fossiliferous, and slabs bearing fossils have become increasingly popular. The most common macrofossils are receptaculitids, followed by corals, stromatoporoid sponges, nautiloid cephalopods, and gastropods. The relative abundance of the macrofossils varies stratigraphically, suggesting that subtle environmental changes took place over time. The distinctive mottles—‘tapestry’ in the trade—have been regarded as dolomitized burrows assigned to Thalassinoides and long thought to have been networks of galleries likely made by arthropods. In detail, however, the bioclastic muddy sediment underwent a protracted history of bioturbation, and the large burrows were mostly horizontal back-filled features that were never empty. They can be assigned to Planolites. The matrix and the sediment filling them were overprinted by several generations of smaller tubular burrows mostly referrable to Palaeophycus due to their distinctive laminated wall linings. Dolomite replaced the interiors of the larger burrows as well as smaller burrows and surrounding matrix during burial, which is why the mottling is so variable in shape.Tyndall Stone est un calcaire dolomitique distinctement marbré et remarquablement fossilifère qui a été largement utilisé pendant plus d'un siècle au Canada, en particulier dans les provinces des Prairies. Ce calcaire s'étend sur 6 à 8 m dans la partie inférieure du membre de Selkirk de la formation de Red River, d'une épaisseur de 43 m et d'âge Ordovicien supérieur (Katien). Il est exploité exclusivement à Garson (Manitoba), à 37 km au nord-est de Winnipeg, depuis environ 1895 et, depuis un demi-siècle, l'extraction est assurée exclusivement par Gillis Quarries Ltd. En raison de l'altération par les eaux souterraines, les couches supérieures ont tendance à être brun clair alors que les couches inférieures sont grises. Le calcaire Tyndall Stone, dont la finition est le plus souvent adoucie ou sciée, a été utilisé à des fins très diverses, notamment pour le revêtement extérieur et intérieur avec des pierres de taille à assises irrégulières, ainsi que pour les encadrements de fenêtres et les embrasures de portes. Le fini éclaté et la pierre de taille de dimension aléatoire utilisant des blocs polychromes fendus le long de stylolites sont devenus populaires pour les bâtiments commerciaux et résidentiels, respectivement. Tyndall Stone se prête également à la taille de colonnes et à la réalisation d’armoiries et de sculptures. De nombreux bâtiments importants ont été construits en Tyndall Stone, notamment les édifices législatifs provinciaux de la Saskatchewan et du Manitoba, l'intérieur de l'édifice du Centre de la Chambre des communes à Ottawa, des palais de justice, des bureaux de titres fonciers, des bureaux de poste et d'autres édifices publics, ainsi que des gares, des banques, des églises, des grands magasins, des musées, des immeubles de bureaux et des bâtiments universitaires. Ces bâtiments présentent une grande variété de styles architecturaux, des Beaux-Arts à l'Art déco, en passant par le style Château et le Brutalisme. Le Musée canadien de l'histoire et le Musée canadien pour les droits de la personne sont deux bâtiments expressionnistes remarquables. Le membre inférieur de Selkirk est massif et se compose de roche sédimentaire carbonatée wackestone à packstone bioturbée et bioclastique, riche en ossicules de crinoïdes. Il s'est déposé dans un environnement marin à faible énergie dans la zone photique, sur l'actuel versant oriental du bassin de Williston peu profond, qui faisait partie de la vaste mer épicontinentale équatoriale couvrant la majeure partie de la Laurentia à l'époque. De minces lentilles éparses de grès bioclastique témoignent d'événements épisodiques à haute énergie. Tyndall Stone est spectaculairement fossilifère et les dalles contenant des fossiles sont de plus en plus populaires. Les macrofossiles les plus courants sont les réceptaculitides, suivis des coraux, des éponges stromatoporoïdes, des céphalopodes nautiloïdes et des gastéropodes. L'abondance relative des macrofossiles varie en fonction de la stratigraphie, ce qui suggère que des changements environnementaux subtils ont eu lieu au fil du temps. Les marbrures distinctives – appelées "tapisserie" dans le commerce – ont été perçues comme des terriers dolomitisés attribués aux Thalassinoides et longtemps considérées comme des réseaux de galeries vraisemblablement creusés par des arthropodes. Dans le détail, cependant, le sédiment vaseux bioclastique a subi une longue histoire de bioturbation, et les grands terriers étaient principalement des éléments horizontaux remblayés qui n'étaient jamais vides. Ils peuvent être attribués à des Planolites. La matrice et les sédiments qui les remplissent sont surchargés par plusieurs générations de terriers tubulaires plus petits, principalement attribuables à des Palaeophycus en raison de leurs revêtements muraux stratifiés distinctifs. La dolomite a remplacé l'intérieur des plus grands terriers ainsi que des plus petits terriers et la matrice environnante pendant l'enfouissement, ce qui explique la forme variable de la marbrure
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