931 resultados para Energy potential


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Diphosphoinositol pentakisphosphate (PP-IP5) and bis(diphospho)inositol tetrakisphosphate (bis-PP-IP4) are recently identified inositol phosphates that possess pyrophosphate bonds. We have purified an inositol hexakisphosphate (IP6) kinase from rat brain supernatants. The pure protein, a monomer of 54 kDa, displays high affinity (Km = 0.7 microM) and selectivity for inositol hexakisphosphate as substrate. It can be dissociated from bis(diphospho)inositol tetrakisphosphate synthetic activity. The purified enzyme transfers a phosphate from PP-IP5 to ADP to form ATP. This ATP synthase activity indicates the high phosphate group transfer potential of PP-IP5 and may represent a physiological role for PP-IP5.

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Although the gene defect responsible for Huntington disease (HD) has recently been identified, the pathogenesis of the disease remains obscure. One potential mechanism is that the gene defect may lead to an impairment of energy metabolism followed by slow excitotoxic neuronal injury. In the present study we examined whether chronic administration of 3-nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase, can replicate the neuropathologic and clinical features of HD in nonhuman primates. After 3-6 weeks of 3-NP administration, apomorphine treatment induced a significant increase in motor activity as compared with saline-treated controls. Animals showed both choreiform movements, as well as foot and limb dystonia, which are characteristic of HD. More prolonged 3-NP treatment in two additional primates resulted in spontaneous dystonia and dyskinesia accompanied by lesions in the caudate and putamen seen by magnetic resonance imaging. Histologic evaluation showed that there was a depletion of calbindin neurons, astrogliosis, sparing of NADPH-diaphorase neurons, and growth-related proliferative changes in dendrites of spiny neurons similar to changes in HD. The striosomal organization of the striatum and the nucleus accumbens were spared. These findings show that chronic administration of 3-NP to nonhuman primates can replicate many of the characteristic motor and histologic features of HD, further strengthening the possibility that a subtle impairment of energy metabolism may play a role in its pathogenesis.

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Some islands in the Gulf of California support very high densities of spiders. Spider density is negatively correlated with island size; many small islands support 50-200 spiders per m3 of cactus. Energy for these spiders comes primarily from the ocean and not from in situ productivity by land plants. We explicitly connect the marine and terrestrial systems to show that insular food webs represent one endpoint of the marine web. We describe two conduits for marine energy entering these islands: shore drift and seabird colonies. Both conduits are related to island area, having a much stronger effect on smaller islands. This asymmetric effect helps to explain the exceptionally high spider densities on small islands. Although productivity sets the maximal potential densities, predation (by scorpions) limits realized spider abundance. Thus, prey availability and predation act in concert to set insular spider abundance.

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We present Tethered Monte Carlo, a simple, general purpose method of computing the effective potential of the order parameter (Helmholtz free energy). This formalism is based on a new statistical ensemble, closely related to the micromagnetic one, but with an extended configuration space (through Creutz-like demons). Canonical averages for arbitrary values of the external magnetic field are computed without additional simulations. The method is put to work in the two-dimensional Ising model, where the existence of exact results enables us to perform high precision checks. A rather peculiar feature of our implementation, which employs a local Metropolis algorithm, is the total absence, within errors, of critical slowing down for magnetic observables. Indeed, high accuracy results are presented for lattices as large as L = 1024.

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We study electron dynamics in a two-band δ-doped semiconductor within the envelope-function approximation. Using a simple parametrization of the confining potential arising from the ionized donors in the δ -doping layer, we are able to find exact solutions of the Dirac-type equation describing the coupling of host bands. As an application we then consider Si δ -doped GaAs. In particular we find that the ground subband energy scales as a power law of the Si concentration per unit area in a wide range of doping levels. In addition, the coupling of host bands leads to a depression of the subband energy due to nonparabolicity effects.

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We present Tethered Monte Carlo, a simple, general purpose method of computing the effective potential of the order parameter (Helmholtz free energy). This formalism is based on a new statistical ensemble, closely related to the micromagnetic one, but with an extended configuration space (through Creutz-like demons). Canonical averages for arbitrary values of the external magnetic field are computed without additional simulations. The method is put to work in the two-dimensional Ising model, where the existence of exact results enables us to perform high precision checks. A rather peculiar feature of our implementation, which employs a local Metropolis algorithm, is the total absence, within errors, of critical slowing down for magnetic observables. Indeed, high accuracy results are presented for lattices as large as L = 1024.

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Copper Mountain, a Colorado ski area, evaluated onsite renewable energy generation to save on energy costs and reduce carbon emissions. Multiple resort locations were analyzed to determine suitable sites for implementation of solar electricity generation, wind electricity generation and biomass heat production. Potential project sites were assessed based on four criteria: costs and financial returns, environmental impacts, implementation and maintenance, and public relations/marketing opportunities. Solar projects had the lowest capital cost of the three types of renewable energy, and wind projects had high capital costs and low financial returns. Biomass projects had high capital costs, solid financial projections and good marketing value compared to wind and solar technologies. Project implementation recommendations were given based upon the evaluation.

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Recent federal incentives and increased demand for home photovoltaic and small wind electrical systems highlights the need for consistent zoning ordinances and guidance materials for Northglenn residents. This Capstone Project assesses perceived impacts related to renewable energy systems, like noise, safety, aesthetics, and environmental considerations, and provides a model ordinance intended to mitigate these issues. It was concluded a model ordinance would ease and stimulate additions of alternative energy systems in Northglenn. Additionally, this research concluded development of public information could stimulate homeowners into positive decisions. The project also identifies potential financial and environmental benefits of installing such systems in an effort to promote sustainable and clean energy production within the city.

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More than ever alternative energy solutions are being discussed including potential legislative action. With the use of fossil fuels being the most abundant and most controversial sources of energy, new solutions must be found. This paper looks at the economic and technical feasibility of different types of alternative energy and cogeneration applications within a steel mill. This paper examines alternative energy systems. The systems examined include Solar systems, thermal electric materials, and an Organic Rankine Cycle cogeneration project. None of the projects has limiting technical feasibility issues however each of the projects face economically limiting factors. Taking into account tangible and non-tangible factors the solar system and Organic Rankine Cycle cogeneration project are recommended for further study and potential installation.

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Despite the economy, the green building industry continues to grow and drive the demand for environmentally conscious, highly skilled professionals (USGBC 2009). LEED Accredited Professionals (APs) have the knowledge and skills to meet such demand; however, information is limited regarding LEED APs or their motivations and expectations toward prospective employers. The author surveyed a sample of LEED Accredited architects and found a combination of job and personal factors motivated them to attain accreditation. LEED APs value both a competitive salary and commitment to sustainability in prospective employers. To attract, retain, and utilize LEED APs, executives in this industry must reexamine corporate culture, their willingness to pay for credentialing, and the alignment of their reputation with the desires of potential applicants.

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We have studied the radial dependence of the energy deposition of the secondary electron generated by swift proton beams incident with energies T = 50 keV–5 MeV on poly(methylmethacrylate) (PMMA). Two different approaches have been used to model the electronic excitation spectrum of PMMA through its energy loss function (ELF), namely the extended-Drude ELF and the Mermin ELF. The singly differential cross section and the total cross section for ionization, as well as the average energy of the generated secondary electrons, show sizeable differences at T ⩽ 0.1 MeV when evaluated with these two ELF models. In order to know the radial distribution around the proton track of the energy deposited by the cascade of secondary electrons, a simulation has been performed that follows the motion of the electrons through the target taking into account both the inelastic interactions (via electronic ionizations and excitations as well as electron-phonon and electron trapping by polaron creation) and the elastic interactions. The radial distribution of the energy deposited by the secondary electrons around the proton track shows notable differences between the simulations performed with the extended-Drude ELF or the Mermin ELF, being the former more spread out (and, therefore, less peaked) than the latter. The highest intensity and sharpness of the deposited energy distributions takes place for proton beams incident with T ~ 0.1–1 MeV. We have also studied the influence in the radial distribution of deposited energy of using a full energy distribution of secondary electrons generated by proton impact or using a single value (namely, the average value of the distribution); our results show that differences between both simulations become important for proton energies larger than ~0.1 MeV. The results presented in this work have potential applications in materials science, as well as hadron therapy (due to the use of PMMA as a tissue phantom) in order to properly consider the generation of electrons by proton beams and their subsequent transport and energy deposition through the target in nanometric scales.

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This paper presents a methodology for calculating the potential impact of the new socio-ecological transition away from fossil fuels on employment in EU energy supply. The methodology is based on “employment factors” (i.e. labour intensities) of different energy technologies. These employment factors are applied to changing energy mixes as projected by the decarbonisation scenarios of the European Commission’s Energy Roadmap 2050. In particular, we analyse quantitative (number of jobs) and qualitative (qualification levels) impacts on employment in extraction and processing of primary (fossil) fuels and in the power sector for the years 2020, 2030 and 2050. The results show that the energy sector will provide not only more jobs as the new socio-ecological transition unfolds, but also jobs requiring higher-level qualifications when compared with the current energy sector.

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Regional approaches to EU energy policies have been termed the ‘Schengenisation’ of energy, making reference to the Schengen Convention eliminating intra-European border controls. They aim to hone the effectiveness of EU energy policy objectives through enhanced policy coordination at the regional scale. Typically, this includes energy market integration while accounting for member states’ continued deployment of national-level policy instruments regarding the appropriate energy mix and the security of energy supply, which is foreseen in the EU Treaty. This report explores the potential for such regional approaches. It assesses lessons from existing initiatives, regional energy arrangements such as the Danube Energy Forum, the Mediterranean Energy Forum, the Pentalateral Energy Forum, the North Seas Countries’ Offshore Grid Initiative and the Nordic Co-operation partnership, to determine whether regional energy initiatives are an efficient, effective and politically acceptable approach toward reaching three EU energy policy objectives: competitiveness, supply security and sustainability. Regional approaches could possibly play an important role for governing EU renewables policy, which the European Commission has identified in the 2030 climate and energy framework as an important element for governance.

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Regional approaches to EU energy policies have been termed the ‘Schengenisation’ of energy, making reference to the Schengen Convention eliminating intra-European border controls. They aim to hone the effectiveness of EU energy policy objectives through enhanced policy coordination at the regional scale. Typically, this includes energy market integration while accounting for member states’ continuing deployment of national-level policy instruments regarding the appropriate energy mix and the security of energy supply, which is foreseen in the EU Treaty. This report explores the potential for such regional approaches. It assesses lessons from existing initiatives, regional energy arrangements such as the Danube Energy Forum, the Mediterranean Energy Forum, the Pentalateral Energy Forum, the North Seas Countries’ Offshore Grid Initiative and the Nordic Co-operation partnership, to determine whether regional energy initiatives are an efficient, effective and politically acceptable approach toward reaching three EU energy policy objectives: competitiveness, supply security and sustainability. Regional approaches could possibly play an important role for governing EU renewables policy, which the European Commission has identified in the 2030 climate and energy framework as an important element for governance.

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Recent Russian actions have unequivocally underlined that it does not play by the rules. This provides a wake-up call and should alert not only the countries of the former Soviet Union, but the EU as a whole. For the EU, this has one clear implication: it cannot continue to depend on an unreliable energy supplier, which is prone to use energy as a political tool. Luckily for the EU, summer is approaching and Europeans will need less Russian gas for heating. However, potential gas supply disruptions remind Europe of its energy vulnerabilities, and of the 2006 and 2009 winters, when Russia’s decision to stop the flow of gas to Ukraine led to supply crises in a number of EU Member States. As the EU’s heads of states and governments gather in the European Council on 20 and 21 March, the developments in Ukraine and the possible Russian illegal annexation of Crimea will undoubtedly dominate the discussions. Securing energy supply will figure on the agenda, but energy should also be seen as a means to pressure Russia. It is important that the Member States use the occasion to commit to working together on energy security. If this is addressed in a holistic way, it can also support European industry and climate policy – the other issues on the Council agenda that run the risk of being forgotten.