2,961 research outputs found

    The Complexity of Helly-B1B_{1} EPG Graph Recognition

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    Golumbic, Lipshteyn, and Stern defined in 2009 the class of EPG graphs, the intersection graph class of edge paths on a grid. An EPG graph GG is a graph that admits a representation where its vertices correspond to paths in a grid QQ, such that two vertices of GG are adjacent if and only if their corresponding paths in QQ have a common edge. If the paths in the representation have at most kk bends, we say that it is a BkB_k-EPG representation. A collection CC of sets satisfies the Helly property when every sub-collection of CC that is pairwise intersecting has at least one common element. In this paper, we show that given a graph GG and an integer kk, the problem of determining whether GG admits a BkB_k-EPG representation whose edge-intersections of paths satisfy the Helly property, so-called Helly-BkB_k-EPG representation, is in NP, for every kk bounded by a polynomial function of ∣V(G)∣|V(G)|. Moreover, we show that the problem of recognizing Helly-B1B_1-EPG graphs is NP-complete, and it remains NP-complete even when restricted to 2-apex and 3-degenerate graphs

    Evaluating megaprojects: from the “iron triangle” to network mapping

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    Evaluation literature has paid relatively little attention to the specific needs of evaluating large, complex industrial and infrastructure projects, often called ‘megaprojects’. The abundant megaproject governance literature, in turn, has largely focused on the so-called ‘megaproject pathologies’, i.e. the chronic budget overruns, and failure of such projects to keep to timetables and deliver the expected social and economic benefits. This article draws on these two strands of literature, identifies shortcomings, and suggests potential pathways towards an improved evaluation of megaprojects. To counterbalance the current overemphasis on relatively narrowly defined accountability as the main function of megaproject evaluation, and the narrow definition of project success in megaproject evaluation, the article argues that conceptualizing megaprojects as dynamic and evolving networks would provide a useful basis for the design of an evaluation approach better able to promote learning and to address the socio economic aspects of megaprojects. A modified version of ‘network mapping’ is suggested as a possible framework for megaproject evaluation, with the exploration of the multiple accountability relationships as a central evaluation task, designed to reconcile learning and accountability as the central evaluation functions. The article highlights the role of evaluation as an ‘emergent’ property of spontaneous megaproject ‘governing’, and explores the challenges that this poses to the role of the evaluator

    Philanthropy or solidarity? Ethical dilemmas about humanitarianism in crisis afflicted Greece

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    That philanthropy perpetuates the conditions that cause inequality is an old argument shared by thinkers such as Karl Marx, Oscar Wilde and Slavoj Zizek. I recorded the same argument in conversations regarding a growing humanitarian concern in austerity-ridden Greece. At the local level a number of solidarity initiatives provide the most impoverished families with humanitarian help. Some citizens participate in such initiatives wholeheartedly, while some other citizens criticize solidarity movements drawing primarily from Marxist-inspired arguments, such as, for example, that humanitarianism rationalises state inaction. The local narratives presented in this article bring forward two parallel possibilities engendered by the humanitarian face of social solidarity: first, its empowering potential (where solidarity initiatives enhance local social awareness), and second, the de-politicisation of the crisis and the experience of suffering (a liability that stems from the effectiveness of humanitarianism in ameliorating only temporarily the superficial consequences of the crisis). These two overlapping possibilities can help us problematise the contextual specificity and strategic employment of humanitarian solidarity in times of austerity

    Improvement and evaluation of the mesoscale meteorological model MM5 for air-quality applications in Southern California and the San Joaquin Valley: Final Report

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    The objective of the Penn State University (PSU) part of the study was to investigate the MM5's ability to simulate wintertime fog in the San Joaquin Valley (SJV) and summertime sea breeze flows in the South Coast Air Basin (SoCAB). For the SJV work the MM5 was configured with four nested grid and an advanced turbulence sub-model. Applied to the event of 7-12 December 1995, observed during the IMS-95 program, the model's innermost domain used 40 vertical layers and a 4-km mesh. Several experiments were performed to improve the turbulence sub-model for saturated conditions and to provide more accurate initial conditions for soil temperature and moisture. Results showed the MM5 correctly predicted the type of visibility obscuration (fog, haze, status or clear) in 14 out of the 18 events. For depth was estimated by the MM5 with a mean absolute error of only 92 m and a mean error of -41 m. Mean errors for both the surface temperature and dew point were within +1C, while the mean absolute errors were ~1.5-2.0 C. As a consequence, the mean error for dew-point depression is very small. Thus, the MM5 was shown to simulate fog and haze in the SJV with considerable accuracy. Extensions of the turbulence sub-model to include saturation effects and the specification of accurate soil temperature and moisture were important for simulating fog characteristics in the case. Additionally, MM5 was able to simulate the light and variable winds in the Sacramento and San Joaquin Valleys that prevailed during this event. Moreover, the winds responded quite well to the slowly changing synoptic-scale weather, as well, as confirmed by the observations. the objective for the San Jose State University (SJSU) work included use of SCOS97 data and MM5 simulations to understand meteorological factors in the formation of high ozone concentrations during 4-7 August 1997. Meteorological data for the case study included observations at 110 SCOS97 surface sites and upper air measurements from 12 rawinsonde and 26 RWP/RASS profilers. the MM5 version contained the PSU Marine Boundary Layer Initialization (MBLI) scheme, quadruple nested grids (horizontal resolutions of 135, 45, 15, and 5 km), 30 vertical layers, minimum sigma level of 46 m, USGS global land-use, GDAS global gridded model analyses and SSTs, analysis nudging, observational nudging, force-restore surface temperature, 1.5 order TKE, one-way continuous nesting, and a MAPS statistical evaluation. Analysis showed the ozone episode resulting from a unique combination of large-scale upper level synoptic forcings that included a weak local coastal 700 mb anticyclone. Its movement around SoCAB rotated the upper level synoptic background flow from its normal westerly onshore direction to a less common offshore easterly flow during the nighttime period preceding the episode. The resulting easterly upper level synoptic background winds influenced surface flow direction at inland sites, so that a surface frontal convergence zone resulted where the easterly flow met the westerly onshore sea breeze flow. The maximum inland penetration of the convergence zone was about to the San Gabriel Mountain peaks, the location of daytime maximum ozone-episode concentrations. The current MM5 simulations reproduced the main qualitative features of the evolution of the diurnal sea breeze cycle in the SoCAB with reasonable accuracy. The position of the sea breeze front during its daytime inland penetration and nighttime retreat could be determined from the simulated wind fields. the accuracy of predicted MM5 surface winds and temperatures over SoCAB were improved by the modifications of its deep-soil temperatures, interpolation of predicted temperatures and winds to SCOS97 observational levels, use of updated urban land-use patterns, and use of corrected input values for ocean and urban surface roughness parameter values.Prepared for the California Air Resources Board and California Environmental Protection AgencySJSU Foundation Subcontract no. 22-1505-7384Approved for public release; distribution is unlimited

    Increased Neutrophil Elastase and Proteinase 3 and Augmented NETosis Are Closely Associated With ÎČ-Cell Autoimmunity in Patients With Type 1 Diabetes

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    Type 1 diabetes (T1D) is an autoimmune disease resulting from the self-destruction of insulin-producing ÎČ-cells. Reduced neutrophil counts have been observed in patients with T1D. However, the pathological roles of neutrophils in the development of T1D remain unknown. Here we show that circulating protein levels and enzymatic activities of neutrophil elastase (NE) and proteinase 3 (PR3), both of which are neutrophil serine proteases stored in neutrophil primary granules, were markedly elevated in patients with T1D, especially those with disease duration of less than 1 year. Furthermore, circulating NE and PR3 levels increased progressively with the increase of the positive numbers and titers of the autoantibodies against ÎČ-cell antigens. An obvious elevation of NE and PR3 was detected even in those autoantibody-negative patients. Increased NE and PR3 in T1D patients are closely associated with elevated formation of neutrophil extracellular traps. By contrast, the circulating levels of α1-antitrypsin, an endogenous inhibitor of neutrophil serine proteases, are decreased in T1D patients. These findings support an early role of neutrophil activation and augmented neutrophil serine proteases activities in the pathogenesis of ÎČ-cell autoimmunity and also suggest that circulating NE and PR3 may serve as sensitive biomarkers for the diagnosis of T1D.postprin

    Aspirin and extended-release dipyridamole versus clopidogrel for recurrent stroke

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    Background Recurrent stroke is a frequent, disabling event after ischemic stroke. This study compared the efficacy and safety of two antiplatelet regimens — aspirin plus extendedrelease dipyridamole (ASA–ERDP) versus clopidogrel. Methods In this double-blind, 2-by-2 factorial trial, we randomly assigned patients to receive 25 mg of aspirin plus 200 mg of extended-release dipyridamole twice daily or to receive 75 mg of clopidogrel daily. The primary outcome was first recurrence of stroke. The secondary outcome was a composite of stroke, myocardial infarction, or death from vascular causes. Sequential statistical testing of noninferiority (margin of 1.075), followed by superiority testing, was planned. Results A total of 20,332 patients were followed for a mean of 2.5 years. Recurrent stroke occurred in 916 patients (9.0%) receiving ASA–ERDP and in 898 patients (8.8%) receiving clopidogrel (hazard ratio, 1.01; 95% confidence interval [CI], 0.92 to 1.11). The secondary outcome occurred in 1333 patients (13.1%) in each group (hazard ratio for ASA–ERDP, 0.99; 95% CI, 0.92 to 1.07). There were more major hemorrhagic events among ASA–ERDP recipients (419 [4.1%]) than among clopidogrel recipients (365 [3.6%]) (hazard ratio, 1.15; 95% CI, 1.00 to 1.32), including intracranial hemorrhage (hazard ratio, 1.42; 95% CI, 1.11 to 1.83). The net risk of recurrent stroke or major hemorrhagic event was similar in the two groups (1194 ASA–ERDP recipients [11.7%], vs. 1156 clopidogrel recipients [11.4%]; hazard ratio, 1.03; 95% CI, 0.95 to 1.11). Conclusions The trial did not meet the predefined criteria for noninferiority but showed similar rates of recurrent stroke with ASA–ERDP and with clopidogrel. There is no evidence that either of the two treatments was superior to the other in the prevention of recurrent stroke. (ClinicalTrials.gov number, NCT00153062.

    Measuring and Predicting Individual Differences in Executive Functions at 14 Months: A Longitudinal Study.

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    This study of 195 (108 boys) children seen twice during infancy (Time 1: 4.12 months; Time 2: 14.42 months) aimed to investigate the associations between and infant predictors of executive function (EF) at 14 months. Infants showed high levels of compliance with the EF tasks at 14 months. There was little evidence of cohesion among EF tasks but simple response inhibition was related to performance on two other EF tasks. Infant attention (but not parent-rated temperament) at 4 months predicted performance on two of the four EF tasks at 14 months. Results suggest that EF skills build on simpler component skills such as attention and response inhibition.ESR

    Mothers' beliefs about children's learning in Hong Kong and the United States: Implications for mothers' child-based worth

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    Chinese and American mothers’ beliefs about children’s learning and parents’ role in it were examined using notions salient in Chinese culture. Mothers from Hong Kong (n = 66) and the United States (n = 69) indicated their endorsement of the ideas that children’s learning reflects children’s morality, and parents’ support of children’s learning reflects parents’ love and duty. Mothers also reported on the extent to which their worth is based on children’s performance. Chinese (vs. American) mothers believed more that children’s learning reflects morality and parents’ support of children’s learning reflects love; these differences accounted for their feelings of worth being more dependent on children’s performance. Chinese (vs. American) mothers believed less that parents’ support is a duty.postprin
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