883 resultados para Fill the gap
Resumo:
Acknowledgements This work was supported by the UK Energy Research Centre Phase 2, under its Energy and Environment theme Grant Number NE/J005924/1 and NE/G007748/1. Open Access funded by Natural Environment Research Council
Resumo:
Perforant path long-term potentiation (LTP) in intact mouse hippocampal dentate gyrus increased the neuron-specific, growth-associated protein GAP-43 mRNA in hilar cells 3 days after tetanus, but surprisingly not in granule cells, the perforant path target. This increase was positively correlated with level of enhancement and restricted to central hilar cells on the side of stimulation. Blockade of LTP by puffing dl-aminophosphonovalerate (APV), an N-methyl-d-aspartate (NMDA) receptor blocker into the molecular layer, eliminated LTP-induced GAP-43 mRNA elevation in hilar cells. To determine whether the mRNA elevation was mediated by transcription, LTP was studied in transgenic mice bearing a GAP-43 promoter-lacZ reporter gene. Promoter activity as indexed by Transgene expression (PATE) increased as indicated by blue staining of the lacZ gene product, β-galactosidase. Potentiation induced a blue band bilaterally in the inner molecular layer of the dentate gyrus along the entire septotemporal axis. Because mossy cells are the only neurons in the central hilar zone that project to the inner molecular layer bilaterally along the entire septotemporal axis and LTP-induced activation of PATE in this zone was confined to the side of stimulation, we concluded that mossy cells were unilaterally activated, increasing synthesis of β-galactosidase, which was transported bilaterally. Neither granule cells nor pyramidal cells demonstrated increased PATE or increased GAP-43 mRNA levels. These results and recent evidence indicating the necessity of hilar neurons for LTP point to previously unheralded mossy cells as potentially critical for perforant path LTP and the GAP-43 in these cells as important for LTP persistence lasting days.
Resumo:
Until the mid-1990s a person could not point to any celestial object and say with assurance that “here is a brown dwarf.” Now dozens are known, and the study of brown dwarfs has come of age, touching upon major issues in astrophysics, including the nature of dark matter, the properties of substellar objects, and the origin of binary stars and planetary systems.
Resumo:
The molecular reaction mechanism of the GTPase-activating protein (GAP)-catalyzed GTP hydrolysis by Ras was investigated by time resolved Fourier transform infrared (FTIR) difference spectroscopy using caged GTP (P3-1-(2-nitro)phenylethyl guanosine 5′-O-triphosphate) as photolabile trigger. This approach provides the complete GTPase reaction pathway with time resolution of milliseconds at the atomic level. Up to now, one structural model of the GAP⋅Ras⋅GDP⋅AlFx transition state analog is known, which represents a “snap shot” along the reaction-pathway. As now revealed, binding of GAP to Ras⋅GTP shifts negative charge from the γ to β phosphate. Such a shift was already identified by FTIR in GTP because of Ras binding and is now shown to be enhanced by GAP binding. Because the charge distribution of the GAP⋅Ras⋅GTP complex thus resembles a more dissociative-like transition state and is more like that in GDP, the activation free energy is reduced. An intermediate is observed on the reaction pathway that appears when the bond between β and γ phosphate is cleaved. In the intermediate, the released Pi is strongly bound to the protein and surprisingly shows bands typical of those seen for phosphorylated enzyme intermediates. All these results provide a mechanistic picture that is different from the intrinsic GTPase reaction of Ras. FTIR analysis reveals the release of Pi from the protein complex as the rate-limiting step for the GAP-catalyzed reaction. The approach presented allows the study not only of single proteins but of protein–protein interactions without intrinsic chromophores, in the non-crystalline state, in real time at the atomic level.
Resumo:
The extractive industry, more than any other sector of the economy, often finds itself mired in conflicts with various environmental and community interests. As traditional legal avenues of resolution gave way to the collaborative ideas of alternative dispute resolution, the outcomes, especially the relational outcomes, were less than desirable. This capstone project proposes that an Anticipatory Cooperative Effort (ACE) can help to bridge the gap between industry and environmental interests by encouraging a pro-active and pre-emptive engagement. The point of the ACE concept is not that it defines a new set of principles so much as it repositions where established ADR principles are entertained.
Resumo:
Surfactant-templating is one of the most versatile and useful techniques to implement mesoporous systems into solid materials. Various strategies based on various interactions between surfactants and solid precursors have been explored to produce new structures. Zeolites are invaluable as size- and shape-selective solid acid catalysts. Nevertheless, their micropores impose limitations on the mass transport of bulky feed and/or product molecules. Many studies have attempted to address this by utilizing surfactant-assisting technology to alleviate the diffusion constraints. However, most efforts have failed due to micro/mesopore phase separation. Recently, a new technique combining the uses of cationic surfactants and mild basic solutions was introduced to synthesise mesostructured zeolites. These materials sustain the unique characteristics of zeolites (i.e., strong acidity, crystallinity, microporosity, and hydrothermal stability), including tunable mesopore sizes and degrees of mesoporosity. The mesostructured zeolites are now commercially available through Rive Technology, and show superior performance in VGO cracking. This feature article provides an overview of recent explorations in the introduction of mesoporosity into zeolites using surfactant-templating techniques. Various porous materials, preparation methods, physical and catalytic properties of mesostructured zeolites will be discussed.
Resumo:
MOOCs and open educational resources (OER) provide a wealth of learning opportunities for people around the globe, many of whom have no access to formal higher education. OER are often difficult to locate and are accessed on their own without support from or dialogue with subject experts and peers. This paper looks at whether it is possible to develop effective learning communities around OER and whether these communities can emerge spontaneously and in a self-organised way without moderation. It examines the complex interplay between formal and informal learning, and examines whether MOOCs are the answer to providing effective interaction and dialogue for those wishing to study at university level for free on the Internet.
Resumo:
The contracting defence budgets in Europe, the difficulties in developing the EU’s security policy, NATO's transformation, the reorientation of US security policy and the problems experienced by European defence industries – all together have in recent years created an increased interest in political, military and military-technological co-operation in Europe.It has manifested itself in concepts of closer co-operation within NATO and the EU (smart defence and pooling&sharing), bilateral and multilateral initiatives outside the structures of NATO and the EU (such as the Nordic Defence Co-operation or the Franco-British co-operation) and debates about the prerequisites, principles and objectives of bilateral, multilateral and regional security and defence co-operation. The present report aims to analyse the potential for security and defence co-operation among selected countries in the area between the Baltic Sea and the Black Sea, i.e. the Nordic states (Denmark, Finland, Norway and Sweden), the Baltic states (Lithuania Latvia and Estonia), Poland's partners in the Visegrad Group (the Czech Republic, Hungary and Slovakia) as well as Romania and Bulgaria. The authors were guided by the assumption that those states are Poland's natural partners for closer regional military co-operation. It may complement ‘the Western’ direction of Poland's security and defence policy, i.e. relations with the partners from the Weimar Triangle and the US. Its goal is not to replace the existing security structures but rather to strengthen military capabilities in the region within NATO and the EU.
Resumo:
Withdrawal from the EU is no more a taboo subject. However, the process by which it can happen is unclear and potentially complex. The purpose of this paper is to show that a withdrawing Member State will not only rid itself from the constraints and obligations of EU rules, but it will also have to re-invent many policies and institutions to fill the gap left by the non-application of EU rules. The paper examines closely the case of the UK and Scotland and concludes that outright exit is not the best option for a withdrawing Member State. The best, but possibly the least feasible, option is an intermediate arrangement falling between full membership and complete separation from the EU. The exact position between the two extremes can only be determined by the exit negotiations and will be influenced by the political climate that will prevail at that time. While the final destination of an acceding country is well known [full adoption of the obligations of EU membership], the exiting country will be embarking on a trip with unknown destination and full of surprises.
Resumo:
This paper argues that the Phillips curve relationship is not sufficient to trace back the output gap, because the effect of excess demand is not symmetric across tradeable and non-tradeable sectors. In the non-tradeable sector, excess demand creates excess employment and inflation via the Phillips curve, while in the tradeable sector much of the excess demand is absorbed by the trade balance. We set up an unobserved-components model including both a Phillips curve and a current account equation to estimate ‘sustainable output’ for 45 countries. Our estimates for many countries differ substantially from the potential output estimates of the European Commission, IMF and OECD. We assemble a comprehensive real-time dataset to estimate our model on data which was available in each year from 2004-15. Our model was able to identify correctly the sign of pre-crisis output gaps using real time data for countries such as the United States, Spain and Ireland, in contrast to the estimates of the three institutions, which estimated negative output gaps real-time, while their current estimates for the pre-crisis period suggest positive gaps. In the past five years the annual output gap estimate revisions of our model, the European Commission, IMF, OECD and the Hodrick-Prescott filter were broadly similar in the range of 0.5-1.0 percent of GDP for advanced countries. Such large revisions are worrisome, because the European fiscal framework can translate the imprecision in output gap estimates into poorly grounded fiscal policymaking in the EU.
Resumo:
Mode of access: Internet.
Resumo:
Title varies slightly.
Resumo:
Mode of access: Internet.