1,561 research outputs found

    Fiscal federalism and prospects for metropolitan transportation authorities in Portugal

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    Fiscal federalism refers to the attribution of public finance functions among different levels of government. We examine Portugal's metropolitan transportation sector through the fiscal federalist lens, in light of the country's decentralization efforts and new relevant legislation. We clarify basic principles of fiscal federalism and adapt them to the finance of metropolitan transportation systems – typically characterized by multiple jurisdictions, numerous externalities and equity concerns – showing the inadequacy of general practice. Portugal's overall public finance system partially adheres to fiscal federalist principles; the transportation sector less so. Metropolitan transportation faces particular troubles, with few direct user fees, prices inadequately reflecting costs, and heavy reliance on central government subsidies for public transportation investments and operations. A new law creating metropolitan transportation authorities is only modestly consistent with fiscal federalist principles, since it inadequately details financial responsibilities and remains under heavy central government control. Absent additional reforms, the new metropolitan authorities should aim to make the transportation finance system explicit and test incentive grants to induce inter-municipal cooperation.MIT Portugal Progra

    Stuck with the bill, but why? : an analysis of the Portuguese public finance system with respect to surface transportation policy and investments

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    Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.Includes bibliographical references (p. 129-140).Despite decentralization progress in other sectors, the Portuguese central government maintains significant administrative and fiscal power over national and sub-national surface transportation operations and infrastructure. This thesis provides a global view of the state of surface transportation in Portugal through an analysis of both the nation's public finance and transportation finance systems as well as a discussion of specific surface transportation systems. It reveals that national and sub-national governments in Portugal are collectively pursuing an unsustainable transportation finance policy that places a significant burden on the public finance system, unfairly privileges the nation's metropolitan areas, and enables a costly and highly politicized tug-of-war between central government and sub-national governments with respect to public transportation investments.by Joshua S. Nelson.S.M.in TransportationM.C.P

    Genome engineering of isogenic human ES cells to model autism disorders.

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    Isogenic pluripotent stem cells are critical tools for studying human neurological diseases by allowing one to study the effects of a mutation in a fixed genetic background. Of particular interest are the spectrum of autism disorders, some of which are monogenic such as Timothy syndrome (TS); others are multigenic such as the microdeletion and microduplication syndromes of the 16p11.2 chromosomal locus. Here, we report engineered human embryonic stem cell (hESC) lines for modeling these two disorders using locus-specific endonucleases to increase the efficiency of homology-directed repair (HDR). We developed a system to: (1) computationally identify unique transcription activator-like effector nuclease (TALEN) binding sites in the genome using a new software program, TALENSeek, (2) assemble the TALEN genes by combining golden gate cloning with modified constructs from the FLASH protocol, and (3) test the TALEN pairs in an amplification-based HDR assay that is more sensitive than the typical non-homologous end joining assay. We applied these methods to identify, construct, and test TALENs that were used with HDR donors in hESCs to generate an isogenic TS cell line in a scarless manner and to model the 16p11.2 copy number disorder without modifying genomic loci with high sequence similarity

    Developing an Integrated Model Framework for the Assessment of Sustainable Agricultural Residue Removal Limits for Bioenergy Systems

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    Agricultural residues have significant potential as a feedstock for bioenergy production, but removing these residues from the land can have negative impacts on soil health. Because of this computational tools are needed that can help guide decisions on the amount of agricultural residue that can be sustainably removed. Models and datasets that can support decisions about sustainable agricultural residue removal are available; however, no tools currently exist that are capable of simultaneously addressing all of the environmental factors that can limit the availability of residue for bioenergy production. This paper presents an integrated framework of models and data that provide a coupled a set of environmental process models and databases that can support agricultural residue removal decisions. Specifically the RUSLE2, WEPS, and Soil Conditioning Index models have been integrated together with the disparate set of databases providing the soils, climate, and management practice data required. The integrated system has been demonstrated for two example cases. In the first case the potential impact of agricultural residue removal is explored. In the second case an aggregate assessment of the agricultural residues available bioenergy production in the state of Iowa is performed

    Targeting angiogenesis as a therapeutic means to reinforce osteocyte survival and prevent nonunions in the aftermath of radiotherapy

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    BackgroundRadiotherapy (XRT) exerts detrimental collateral effects on bone tissue through mechanisms of vascular damage and impediments to osteocytes, ultimately predisposing patients to the debilitating problems of late pathologic fractures and nonunions. We posit that angiogenic therapy will reverse these pathologic effects in a rat model of radiated fracture healing.MethodsThree groups of rats underwent mandibular osteotomy. Radiated groups received a fractionated 35‐Gy dose before surgery. The deferoxamine (DFO) group received local injections postoperatively. A 40‐day healing period was allowed before histology. Analysis of variance (ANOVA; p < .05) was used for group comparisons.ResultsRadiated fractures revealed a significantly decreased osteocyte count and corresponding increase in empty lacunae when compared to nonradiated fractures (p = .001). With the addition of DFO, these differences were not appreciated. Further, a 42% increase in bony unions was observed after DFO therapy.ConclusionTargeting angiogenesis is a useful means for promoting osteocyte survival and preventing bone pathology after XRT. © 2014 Wiley Periodicals, Inc. Head Neck 37: 1261–1267, 2015Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113164/1/hed23744.pd

    Insights into the behaviour of systems biology models from dynamic sensitivity and identifiability analysis: a case study of an NF-kB signaling pathway

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    Mathematical modelling offers a variety of useful techniques to help in understanding the intrinsic behaviour of complex signal transduction networks. From the system engineering point of view, the dynamics of metabolic and signal transduction models can always be described by nonlinear ordinary differential equations (ODEs) following mass balance principles. Based on the state-space formulation, many methods from the area of automatic control can conveniently be applied to the modelling, analysis and design of cell networks. In the present study, dynamic sensitivity analysis is performed on a model of the IB-NF-B signal pathway system. Univariate analysis of the Euclidean-form overall sensitivities shows that only 8 out of the 64 parameters in the model have major influence on the nuclear NF-B oscillations. The sensitivity matrix is then used to address correlation analysis, identifiability assessment and measurement set selection within the framework of least squares estimation and multivariate analysis. It is shown that certain pairs of parameters are exactly or highly correlated to each other in terms of their effects on the measured variables. The experimental design strategy provides guidance on which proteins should best be considered for measurement such that the unknown parameters can be estimated with the best statistical precision. The whole analysis scheme we describe provides efficient parameter estimation techniques for complex cell networks

    Permanent pacing is a risk factor for the development of heart failure.

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    No previous study has examined the importance of right ventricular pacing as a risk factor for the development of heart failure (HF) in subjects without a history of HF. A cohort study of patients who underwent initial pacemaker implantation (n = 11,426) was conducted to test the hypothesis that patients with ventricular dyssynchrony created by permanent pacing would develop HF, as shown by new HF hospitalizations or HF-related deaths, at a higher rate than matched controls
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