676 research outputs found

    Vulnerability analysis of satellite-based synchronized smart grids monitoring systems

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    The large-scale deployment of wide-area monitoring systems could play a strategic role in supporting the evolution of traditional power systems toward smarter and self-healing grids. The correct operation of these synchronized monitoring systems requires a common and accurate timing reference usually provided by a satellite-based global positioning system. Although these satellites signals provide timing accuracy that easily exceeds the needs of the power industry, they are extremely vulnerable to radio frequency interference. Consequently, a comprehensive analysis aimed at identifying their potential vulnerabilities is of paramount importance for correct and safe wide-area monitoring system operation. Armed with such a vision, this article presents and discusses the results of an experimental analysis aimed at characterizing the vulnerability of global positioning system based wide-area monitoring systems to external interferences. The article outlines the potential strategies that could be adopted to protect global positioning system receivers from external cyber-attacks and proposes decentralized defense strategies based on self-organizing sensor networks aimed at assuring correct time synchronization in the presence of external attacks

    Developmental trends in voice onset time: some evidence for sex differences

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    This study reports on an investigation into the voice onset time (VOT) patterns of the plosives /p b t d/ in a group of 30 children aged 7 (n = 10), 9 (n = 10) and 11 (n = 10) years. Equal numbers of girls and boys participated in the study. Each child named a series of letter objects to elicit /p b t d/ in a syllable onset position with a fixed vowel context. VOT data were examined for age, sex and plosive differences with the following hypotheses: Firstly, that there would be sex differences in the VOT patterns of preadolescent children. Secondly, that the sex differences in VOT patterns would be linked to age and development, and that these would eventually become marked by the age of 11 years, by which time adult-like VOT values should have been achieved. Finally, that the extent of sex and age differences would be dependent upon the plosive being investigated. Results indicated patterns of decrease with age in the VOT values of /p b/ for the boys, with some evidence of increases in the VOT values of /t/ for the girls. In addition, 'voiced' and 'voiceless' cognates showed a more marked bimodal distribution in the girls' VOT patterns. This bimodal distribution was investigated by examining the degree of difference between the VOT values of voiced and voiceless cognate pairs /p b/ and /t d/, and examining the effects of age, sex and cognate pair. These results indicated that more marked sex differences in the 'voiced'/'voiceless' contrast emerged between the data of the 9- and 11-year-olds, a pattern, which was more marked for the alveolar plosives. These preliminary results confirmed all three hypotheses. The findings are presented and discussed both within a developmental and sociophonetic framework

    Geomagnetic Disturbances (GMD) Impacts on Protection Systems

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    This paper provides background and historical events of Geomagnetic Disturbances (GMD), and reviews GMD impacts on power systems equipment, and associated protection and control systems, mitigating measures, and Geomagnetic Induced Current (GIC) monitoring methods. This paper is a summary of the IEEE PES-TR72 report, titled, GMD Impacts on Protection Systems, prepared by the K17 Working Group of the IEEE Power System Relaying and Control committee

    Increase the strength characteristics of polymer films by radiation graft polymerization

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    The possibility of increasing the strength characteristics of polymer films based on polyethylene and polyamide by radiation graft polymerization was investigated. Two methods of graft polymerization (direct method and the method of polymer mixtures cross-linking) on the PMMA films surface were studied. The possibility of increasing the strength and elasticity of polymeric films by radiation modification of polymethyl methacrylate was shown

    Parameter-Independent Strategies for pMDPs via POMDPs

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    Markov Decision Processes (MDPs) are a popular class of models suitable for solving control decision problems in probabilistic reactive systems. We consider parametric MDPs (pMDPs) that include parameters in some of the transition probabilities to account for stochastic uncertainties of the environment such as noise or input disturbances. We study pMDPs with reachability objectives where the parameter values are unknown and impossible to measure directly during execution, but there is a probability distribution known over the parameter values. We study for the first time computing parameter-independent strategies that are expectation optimal, i.e., optimize the expected reachability probability under the probability distribution over the parameters. We present an encoding of our problem to partially observable MDPs (POMDPs), i.e., a reduction of our problem to computing optimal strategies in POMDPs. We evaluate our method experimentally on several benchmarks: a motivating (repeated) learner model; a series of benchmarks of varying configurations of a robot moving on a grid; and a consensus protocol.Comment: Extended version of a QEST 2018 pape

    Entrance-channel Mass-asymmetry Dependence of Compound-nucleus Formation Time in Light Heavy-ion Reactions

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    The entrance-channel mass-asymmetry dependence of the compound nucleus formation time in light heavy-ion reactions has been investigated within the framework of semiclassical dissipative collision models. the model calculations have been succesfully applied to the formation of the 38^{38}Ar compound nucleus as populated via the 9^{9}Be+29^{29}Si, 11^{11}B+27^{27}Al, 12^{12}C+26^{26}Mg and 19^{19}F+19^{19}F entrance channels. The shape evolution of several other light composite systems appears to be consistent with the so-called "Fusion Inhibition Factor" which has been experimentally observed. As found previously in more massive systems for the fusion-evaporation process, the entrance-channel mass-asymmetry degree of freedom appears to determine the competition between the different mechanisms as well as the time scales involved.Comment: 12 pages, 3 Figures available upon request, Submitted at Phys. Rev.

    RECENT ADVANCES ON STABILITY OF ANTHOCYANINS

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    Since Neolithic era, natural pigments have been added to foods and colour of food products is still one of the major concerns of food industry. Anthocyanins are the most noticeable group among coloured flavonoids, widely existing in the roots, stems and leaves as well as flowers and fruits of the vascular plants. They have a high potential for use as natural colorants instead of synthetic pigments because of their attractive colour and pharmacological properties. Stable and attractive colours are a highly valued attribute in competitive food industry. Considerable studies have been done on the effects of the most important chemical and physical factors involved in the stability of anthocyanins (temperature, light, pH, SO2, metal, sugar, ascorbic acid and oxygen), their concentrations, chemical structures, and matrix food compositions. Furthermore, the effects of separation technologies including microwave/ultrasound assisted extraction (MAE, UAE), and Colloidal Gaz Aphron (CGA) fractionation on the stability of anthocyanins are reviewed

    Isotopic Scaling of Heavy Projectile Residues from the collisions of 25 MeV/nucleon 86Kr with 124Sn, 112Sn and 64Ni, 58Ni

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    The scaling of the yields of heavy projectile residues from the reactions of 25 MeV/nucleon 86Kr projectiles with 124Sn,112Sn and 64Ni, 58Nitargets is studied. Isotopically resolved yield distributions of projectile fragments in the range Z=10-36 from these reaction pairs were measured with the MARS recoil separator in the angular range 2.7-5.3 degrees. The velocities of the residues, monotonically decreasing with Z down to Z~26-28, are employed to characterize the excitation energy. The yield ratios R21(N,Z) for each pair of systems are found to exhibit isotopic scaling (isoscaling), namely, an exponential dependence on the fragment atomic number Z and neutron number N. The isoscaling is found to occur in the residue Z range corresponding to the maximum observed excitation energies. The corresponding isoscaling parameters are alpha=0.43 and beta=-0.50 for the Kr+Sn system and alpha=0.27 and beta=-0.34 for the Kr+Ni system. For the Kr+Sn system, for which the experimental angular acceptance range lies inside the grazing angle, isoscaling was found to occur for Z<26 and N<34. For heavier fragments from Kr+Sn, the parameters vary monotonically, alpha decreasing with Z and beta increasing with N. This variation is found to be related to the evolution towards isospin equilibration and, as such, it can serve as a tracer of the N/Z equilibration process. The present heavy-residue data extend the observation of isotopic scaling from the intermediate mass fragment region to the heavy-residue region. Such high-resolution mass spectrometric data can provide important information on the role of isospin in peripheral and mid-peripheral collisions, complementary to that accessible from modern large-acceptance multidetector devices.Comment: 8 pages, 6 figures, submitted to Phys. Rev.

    Sex-specific differences in chronic thromboembolic pulmonary hypertension. Results from the European CTEPH registry

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    BACKGROUND Women are more susceptible than men to several forms of pulmonary hypertension, but have better survival. Sparse data are available on chronic thromboembolic pulmonary hypertension (CTEPH). METHODS We investigated sex-specific differences in the clinical presentation of CTEPH, performance of pulmonary endarterectomy (PEA), and survival. RESULTS Women constituted one-half of the study population of the European CTEPH registry (N = 679) and were characterized by a lower prevalence of some cardiovascular risk factors, including prior acute coronary syndrome, smoking habit, and chronic obstructive pulmonary disease, but more prevalent obesity, cancer, and thyroid diseases. The median age was 62 (interquartile ratio, 50-73) years in women and 63 (interquartile ratio, 53-70) in men. Women underwent PEA less often than men (54% vs 65%), especially at low-volume centers (48% vs 61%), and were exposed to fewer additional cardiac procedures, notably coronary artery bypass graft surgery (0.5% vs 9.5%). The prevalence of specific reasons for not being operated, including patient's refusal and the proportion of proximal vs distal lesions, did not differ between sexes. A total of 57 (17.0%) deaths in women and 70 (20.7%) in men were recorded over long-term follow-up. Female sex was positively associated with long-term survival (adjusted hazard ratio, 0.66; 95% confidence interval, 0.46-0.94). Short-term mortality was identical in the two groups. CONCLUSIONS Women with CTEPH underwent PEA less frequently than men, especially at low-volume centers. Furthermore, they had a lower prevalence of cardiovascular risk factors and were less often exposed to additional cardiac surgery procedures. Women had better long-term survival

    Dietary soy and meat proteins induce distinct physiological and gene expression changes in rats

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    This study reports on a comprehensive comparison of the effects of soy and meat proteins given at the recommended level on physiological markers of metabolic syndrome and the hepatic transcriptome. Male rats were fed semi-synthetic diets for 1 wk that differed only regarding protein source, with casein serving as reference. Body weight gain and adipose tissue mass were significantly reduced by soy but not meat proteins. The insulin resistance index was improved by soy, and to a lesser extent by meat proteins. Liver triacylglycerol contents were reduced by both protein sources, which coincided with increased plasma triacylglycerol concentrations. Both soy and meat proteins changed plasma amino acid patterns. The expression of 1571 and 1369 genes were altered by soy and meat proteins respectively. Functional classification revealed that lipid, energy and amino acid metabolic pathways, as well as insulin signaling pathways were regulated differently by soy and meat proteins. Several transcriptional regulators, including NFE2L2, ATF4, Srebf1 and Rictor were identified as potential key upstream regulators. These results suggest that soy and meat proteins induce distinct physiological and gene expression responses in rats and provide novel evidence and suggestions for the health effects of different protein sources in human diets
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