Chemical Accident Hazard Assessment by Spatial Analysis of Chemical Factories and Accident Records in South Korea

This study identified the potential chemical accident occurrence in Korea by analyzing the spatial distribution of chemical factories and accidents. The number of chemical factories and accidents in 25-km2 grids were used as the attribute value for spatial analysis. First, semi-variograms were conducted to examine spatial distribution patterns and to identify spatial autocorrelation of chemical factories and accidents. Semi-variograms explained that the spatial distribution of chemical factories and accidents were spatially autocorrelated. Second, the results of the semi-variograms were used in Ordinary Kriging to estimate chemical hazard levels. The level values were extracted from the Ordinary Kriging result and their spatial similarity was examined by juxtaposing the two values with respect to their location. Six peaks were identified in both the factory hazard and accident hazard estimation result, and the peaks correlated with major cities in Korea. Third, the estimated two hazard levels were classified with geometrical interval and could be classified into four quadrants: Low Factory and Low Accident (LFLA), High Factory and Low Accident (HFLA), Low Factory and High Accident(LFHA), and High Factory and High Accident (HFHA). The 4 groups identified different chemical safety management issues in Korea; safe LFLA group, many chemical reseller factories were found in HFLA group, chemical transportation accidents were in the LFHA group, and an abundance of factories and accidents were in the HFHA group. Each quadrant represented different safety management obstacles in Korea, and studying spatial differences can support the establishment of an efficient risk management plan

Square to stripe transition and superlattice patterns in vertically oscillated granular layers

We investigated the physical mechanism for the pattern transition from square lattice to stripes, which appears in vertically oscillating granular layers. We present a continuum model to show that the transition depends on the competition between inertial force and local saturation of transport. By introducing multiple free-flight times, this model further enables us to analyze the formation of superlattices as well as hexagonal lattice

Quantum-critical pairing with varying exponents

We analyse the onset temperature T_p for the pairing in cuprate superconductors at small doping, when tendency towards antiferromagnetism is strong. We consider the model of Moon and Sachdev (MS), which assumes that electron and hole pockets survive in a paramagnetic phase. Within this model, the pairing between fermions is mediated by a gauge boson, whose propagator remains massless in a paramagnet. We relate the MS model to a generic \gamma-model of quantum-critical pairing with the pairing kernel \lambda (\Omega) \propto 1/\Omega^{\gamma}. We show that, over some range of parameters, the MS model is equivalent to the \gamma-model with \gamma =1/3 (\lambda (\Omega) \propto \Omega^{-1/3}). We find, however, that the parameter range where this analogy works is bounded on both ends. At larger deviations from a magnetic phase, the MS model becomes equivalent to the \gamma-model with varying \gamma >1/3, whose value depends on the distance to a magnetic transition and approaches \gamma =1 deep in a paramagnetic phase. Very near the transition, the MS model becomes equivalent to the \gamma-model with varying \gamma <1/3. Right at the magnetic QCP, the MS model is equivalent to the \gamma-model with \gamma =0+ (\lambda (\Omega) \propto \log \Omega), which is the model for color superconductivity. Using this analogy, we verified the formula for T_c derived for color superconductivity.Comment: 10 pages, 8 figures, submitted to JLTP for a focused issue on Quantum Phase Transition

Nonalcoholic Fatty Liver Disease Risk Factors Affect Liver-Related Outcomes After Direct-Acting Antiviral Treatment for Hepatitis C

Introduction: In hepatitis C (HCV) patients, obesity and/or diabetes may increase the risk of liver-related outcomes. We aimed to determine whether diabetes and/or obesity are associated with adverse outcomes in direct-acting antiviral (DAA)-treated HCV patients. Methods: We conducted a retrospective study of 33,003 HCV-infected, DAA-treated Veterans between 2013 and 2015. Body mass index was used to categorize patients into underweight (&lt; 18.5 kg/m2), normal weight (18.5 to &lt; 25 kg/m2), overweight (25 to &lt; 30 kg/m2), obesity I (30 to &lt; 35 kg/m2), and obesity II–III (&gt; 35 kg/m2). Diabetes was defined by ICD-9/10 codes in association with hemoglobin A1c &gt; 6.5% or medication prescriptions. Patients were followed from 180 days post-DAA initiation until 2/14/2019 to assess for development of cirrhosis, decompensations, hepatocellular carcinoma (HCC), and death. Multivariable Cox proportional hazards regression models were used to determine the association between diabetes and/or obesity and outcomes. Results: During a mean follow-up of 3 years, 10.1% patients died, 5.0% were newly diagnosed with cirrhosis, 4.7% had a decompensation and 4.0% developed HCC. Diabetes was associated with an increased risk of mortality (AHR = 1.25, 95% CI 1.10–1.42), cirrhosis (AHR = 1.31, 95% CI 1.16–1.48), decompensation (AHR = 1.74, 95% CI 1.31–2.31), and HCC (AHR = 1.32, 95% CI 1.01–1.72) among patients without baseline cirrhosis. Compared to normal-weight persons, obese persons had a higher risk of cirrhosis, but overweight and obese persons had lower risk of mortality and HCC. Conclusions: In this large DAA-treated Veterans cohort, pre-DAA diabetes increases mortality and liver-related events independent of SVR. Continued vigilance is warranted in patients with diabetes despite SVR. Elevated BMI categories appear to have improved outcomes, although further studies are needed to understand those associations

Stability and consolidation of sediment tailings incorporating unsaturated soil mechanics

YesTailing dams are commonly used to safely store tailings without damaging the environment. Sand tailings (also called Sediment tailings) usually have a high water content and hence undergo consolidation during their placement. As the sediment tailings are usually placed above the ground water level, the degree of saturation and permeability of the sediment tailing is associated with the unsaturated condition due to the presence of negative pore-water pressure or suction. Current practices normally focus on the analyses saturated conditions. However, this consolidation process requires the flow of water between saturated and unsaturated zones to be considered. The objective of this study is to investigate the stability and consolidation of sediment tailings for the construction of road pillars considering the water flow between saturated and unsaturated zones. The scope of this study includes the unsaturated laboratory testing of sediments and numerical analyses of the road pillar. The results show that the analyses based on saturated conditions overestimate the time required to achieve a 90% degree of consolidation. The incorporation of the unsaturated soil properties is able to optimize the design of slopes for road pillars into steeper slope angles

Slow relaxations and history dependence of the transport properties of layered superconductors

We study numerically the time evolution of the transport properties of layered superconductors after different preparations. We show that, in accordance with recent experiments in BSCCO performed in the second peak region of the phase diagram (Portier et al, 2001), the relaxation strongly depends on the initial conditions and is extremely slow. We investigate the dependence on the pinning center density and the perturbation applied. We compare the measurements to recent findings in tapped granular matter and we interpret our results with a rather simple picture.Comment: 4 pages, 4 fig

Modelling and Interpreting The Effects of Spatial Resolution on Solar Magnetic Field Maps

Different methods for simulating the effects of spatial resolution on magnetic field maps are compared, including those commonly used for inter-instrument comparisons. The investigation first uses synthetic data, and the results are confirmed with {\it Hinode}/SpectroPolarimeter data. Four methods are examined, one which manipulates the Stokes spectra to simulate spatial-resolution degradation, and three "post-facto" methods where the magnetic field maps are manipulated directly. Throughout, statistical comparisons of the degraded maps with the originals serve to quantify the outcomes. Overall, we find that areas with inferred magnetic fill fractions close to unity may be insensitive to optical spatial resolution; areas of sub-unity fill fractions are very sensitive. Trends with worsening spatial resolution can include increased average field strength, lower total flux, and a field vector oriented closer to the line of sight. Further-derived quantities such as vertical current density show variations even in areas of high average magnetic fill-fraction. In short, unresolved maps fail to represent the distribution of the underlying unresolved fields, and the "post-facto" methods generally do not reproduce the effects of a smaller telescope aperture. It is argued that selecting a method in order to reconcile disparate spatial resolution effects should depend on the goal, as one method may better preserve the field distribution, while another can reproduce spatial resolution degradation. The results presented should help direct future inter-instrument comparisons.Comment: Accepted for publication in Solar Physics. The final publication (including full-resolution figures) will be available at http://www.springerlink.co

Bond of 13 mm prestressing steel strands in pretensioned concrete members

This paper presents an experimental research work to determine both the transmission and the anchorage lengths of seven-wire prestressing steel strands in different concrete mixes. A testing technique based on a bond behavior analysis by measuring the force supported by the prestressing strand on a series of specimens with different embedment lengths has been used. Relationships between the average bond stress for both the transmission length and anchorage length as a function of the concrete compressive strength have been found. Equations to compute transmission and anchorage lengths of 13 mm prestressing strands have been obtained. The experimental results have been compared with the theoretical prediction from proposed equations in the literature and with experimental results from other authors. 2012 Elsevier Ltd. All rights reserved.The content of this article forms part of the research work that the Institute of Concrete Science and Technology (ICITECH) is presently conducting in conjunction with PREVALESA and ISOCRON. This study has been funded by the Spanish Ministry of Education and Science and ERDF (Project BIA2006-05521). The authors wish to thank the above companies as well as the concrete structures laboratory technicians at the Universitat Politecnica de Valencia for their cooperation. Finally, the authors also wish to pay their respects to C.A. Arbelaez.Martí Vargas, JR.; Serna Ros, P.; Navarro Gregori, J.; Pallarés Rubio, L. (2012). Bond of 13 mm prestressing steel strands in pretensioned concrete members. Engineering Structures. 41:403-412. https://doi.org/10.1016/j.engstruct.2012.03.056S4034124

Metastability and Transient Effects in Vortex Matter Near a Decoupling Transition

We examine metastable and transient effects both above and below the first-order decoupling line in a 3D simulation of magnetically interacting pancake vortices. We observe pronounced transient and history effects as well as supercooling and superheating between the 3D coupled, ordered and 2D decoupled, disordered phases. In the disordered supercooled state as a function of DC driving, reordering occurs through the formation of growing moving channels of the ordered phase. No channels form in the superheated region; instead the ordered state is homogeneously destroyed. When a sequence of current pulses is applied we observe memory effects. We find a ramp rate dependence of the V(I) curves on both sides of the decoupling transition. The critical current that we obtain depends on how the system is prepared.Comment: 10 pages, 15 postscript figures, version to appear in PR

Variable Reuse for Efficient Image Computation

Image computation, that is, computing the set of states reachable from a given set in one step, is a crucial component in typical tools for BDD-based symbolic reachability analysis. It has been shown that the size of the intermediate BDDs during image computation can be dramatically reduced via conjunctive partitioning of the transition relation and ordering the conjuncts for facilitating early quantification. In this paper, we propose to enhance the effectiveness of these techniques by reusing the quantified variables. Given an ordered set of conjuncts, if the last conjunct that uses a variable u appears before the first conjunct that uses another variable v, then v can be renamed to u, assuming u will be quantified immediately after its last use. In general, multiple variables can share the same identifier so the BDD nodes that are inactive but not garbage collected may be activated. We give a polynomial-time algorithm for generating the optimum number of variables that are required for image computation and show how to modify the image computation accounting for variable reuse. The savings for image computation are demonstrated on ISCAS\u2789 and Texas\u2797 benchmark models