4,948 research outputs found

    Modelling the Network Effects of Road User Charging: Results from a SATURN Study.

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    The aim of this research has been to investigate the modelled effects of alternative road user charging systems upon an existing road network using the congested assignment models SATURN and CONTRAM applied to the city of Cambridge. Four road user charging systems which are being considered for practical application have been tested. These are toll cordons, time-based charging, a congestion charging system similar to that proposed in Cambridge and distance-based charging. Tests have been conducted using current morning peak travel demand patterns both with a fixed trip matrix, to isolate rerouteing issues and using the SATURN elastic assignment program, SATEASY, in order to address the effects of charging upon the frequency, timing and distribution of trips. Network impacts have been assessed using a series global indicators, in particular effects on vehicle-km, vehicle-hours and the resulting average network speeds. In addition, results have been obtained for total delay times, cordon crossing flows and revenues generated from charging. These results are presented and their implications discussed

    Water constraints on European power supply under climate change: Impacts on electricity prices

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    Recent warm, dry summers showed the vulnerability of the European power sector to low water availability and high river temperatures. Climate change is likely to impact electricity supply, in terms of both water availabilty for hydropower generation and cooling water usage for thermoelectric power production. Here, we show the impacts of climate change and changes in water availability and water temperature on European electricity production and prices. Using simulations of daily river flows and water temperatures under future climate (2031-2060) in power production models, we show declines in both thermoelectric and hydropower generating potential for most parts of Europe, except for the most northern countries. Based on changes in power production potentials, we assess the cost-optimal use of power plants for each European country by taking electricity import and export constraints into account. Higher wholesale prices are projected on a mean annual basis for most European countries (except for Sweden and Norway), with strongest increases for Slovenia (12-15%), Bulgaria (21-23%) and Romania (31-32% for 2031-2060), where limitations in water availability mainly affect power plants with low production costs. Considering the long design life of power plant infrastructures, short-term adaptation strategies are highly recommended to prevent undesired distributional and allocative effects

    A method to simulate incentives for cost containment under various cost sharing designs: an application to a first-euro deductible and a doughnut hole

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    Many health insurance schemes include deductibles to provide consumers with cost containment incentives (CCI) and to counteract moral hazard. Policymakers are faced with choices on the implementation of a specific cost sharing design. One of the guiding principles in this decision process could be which design leads to the strongest CCI. Despite the vast amount of literature on the effects of cost sharing

    Microscopic energy flows in disordered Ising spin systems

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    An efficient microcanonical dynamics has been recently introduced for Ising spin models embedded in a generic connected graph even in the presence of disorder i.e. with the spin couplings chosen from a random distribution. Such a dynamics allows a coherent definition of local temperatures also when open boundaries are coupled to thermostats, imposing an energy flow. Within this framework, here we introduce a consistent definition for local energy currents and we study their dependence on the disorder. In the linear response regime, when the global gradient between thermostats is small, we also define local conductivities following a Fourier dicretized picture. Then, we work out a linearized "mean-field approximation", where local conductivities are supposed to depend on local couplings and temperatures only. We compare the approximated currents with the exact results of the nonlinear system, showing the reliability range of the mean-field approach, which proves very good at high temperatures and not so efficient in the critical region. In the numerical studies we focus on the disordered cylinder but our results could be extended to an arbitrary, disordered spin model on a generic discrete structures.Comment: 12 pages, 6 figure

    Channeling in direct dark matter detection I: channeling fraction in NaI (Tl) crystals

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    The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in NaI (Tl) crystals using analytic models produced since the 1960's and 70's to describe channeling and blocking effects. We find that the channeling fraction of recoiling lattice nuclei is smaller than that of ions that are injected into the crystal and that it is strongly temperature dependent.Comment: 37 pages, 35 figures, Accepted for publication in JCAP on 27 October 2010, Minor revisions: added an appendix, updated references, updated Fig. 9, corrected a few typo

    Channeling Effects in Direct Dark Matter Detectors

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    The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in NaI (Tl), Si and Ge crystals using analytic models produced since the 1960's and 70's to describe channeling and blocking effects. We find that the channeling fraction of recoiling lattice nuclei is smaller than that of ions that are injected into the crystal and that it is strongly temperature dependent.Comment: 8 pages, 12 figures, To appear in the Proceedings of the sixth International Workshop on the Dark Side of the Universe (DSU2010) Leon, Guanajuato, Mexico 1-6 June 201

    Serum prolactin as a biomarker for the study of intracerebral dopamine effect in adult patients with phenylketonuria: a cross-sectional monocentric study

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    BACKGROUND: It has been previously postulated that high phenylalanine (Phe) might disturb intracerebral dopamine production, which is the main regulator of prolactin secretion in the pituitary gland. Previously, various associations between Phe and hyperprolactinemia were revealed in studies performed in phenylketonuria (PKU) children and adolescents. The aim of the present study was to clarify whether any relation between serum phenylalanine and prolactin levels can be found in adult PKU patients. PATIENTS AND METHODS: We conducted a cross-sectional, monocentric study including 158 adult patients (male n = 68, female n = 90) with PKU. All patients were diagnosed during newborn screening and were treated since birth. Serum Phe, tyrosine (Tyr), prolactin (PRL), and thyroid-stimulating hormone (TSH) levels were measured, and Phe/Tyr ratio was calculated. Males and females were analyzed separately because the serum prolactin level is gender-dependent. RESULTS: No significant correlations were found between serum phenylalanine, tyrosine, or the Phe/Tyr ratio and serum prolactin level either in the male or in the female group. CONCLUSIONS: In treated adult PKU patients, the serum prolactin level may not be significantly influenced by Phe or Tyr serum levels

    Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

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    Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit cyclic volumetric expansion upon reversible ion transport. Such chemomechanical coupling is typically far from thermodynamic equilibrium, and thus is challenging to quantify experimentally and computationally. In situ measurements and atomistic simulations are under rapid development to explore how this coupling can be used to potentially improve both device performance and durability. Here, we review the commonalities of coupling between electrochemical and mechanical states in fuel cell and battery materials, illustrating with specific cases the progress in materials processing, in situ characterization, and computational modeling and simulation. We also highlight outstanding questions and opportunities in these applications – both to better understand the limiting mechanisms within the materials and to significantly advance the durability and predictability of device performance required for renewable energy conversion and storage.United States. Dept. of Energy (Basic Energy Sciences Division of Materials Sciences and Engineering, grant DE-SC0002633)United States. Dept. of Energy (Office of Science, Graduate Fellowship Program (DOE SCGF))United States. American Recovery and Reinvestment Act of 2009 (ORISE-ORAU, contract no. DE-AC05-06OR23100))United States. Dept. of Energy. Division of Materials Sciences and Engineering (MIT/DMSE Salapatas Fellowship)United States. Air Force Office of Scientific Research (Presidential Early Career Award in Science and Engineering (PECASE)
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