Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependency

Increased coupling between critical infrastructure networks, such as power and communication systems, will have important implications for the reliability and security of these systems. To understand the effects of power-communication coupling, several have studied interdependent network models and reported that increased coupling can increase system vulnerability. However, these results come from models that have substantially different mechanisms of cascading, relative to those found in actual power and communication networks. This paper reports on two sets of experiments that compare the network vulnerability implications resulting from simple topological models and models that more accurately capture the dynamics of cascading in power systems. First, we compare a simple model of topological contagion to a model of cascading in power systems and find that the power grid shows a much higher level of vulnerability, relative to the contagion model. Second, we compare a model of topological cascades in coupled networks to three different physics-based models of power grids coupled to communication networks. Again, the more accurate models suggest very different conclusions. In all but the most extreme case, the physics-based power grid models indicate that increased power-communication coupling decreases vulnerability. This is opposite from what one would conclude from the coupled topological model, in which zero coupling is optimal. Finally, an extreme case in which communication failures immediately cause grid failures, suggests that if systems are poorly designed, increased coupling can be harmful. Together these results suggest design strategies for reducing the risk of cascades in interdependent infrastructure systems

ОСВІТНІ ТРАДИЦІЇ ЗДОРОВОГО СПОСОБУ ЖИТТЯ УЧНІВ НАРОДНИХ ШКІЛ ЗАКАРПАТТЯ (1919–1939)

It is proved that the education of a healthy lifestyle of junior schoolchildren took place through information, training and actually educational activities aimed at the formation of sanitary and hygienic culture, healthy lifestyle, development good habits (adherence to the daily routine, proper diet, physical activity) and prevention of harmful habits (smoking, alcohol consumption, etc.). The aim of the article is to identify educational traditions of healthy lifestyle of primary school children; the analysis of the content of school textbooks used in Transcarpathian public schools during the interwar period for the content of materials on support and promotion of health. The main results of the study are to outline the possibilities of education of healthy lifestyle in primary education contents and their reflection in the subject “Citizenship Science and Education” (Civics). It has been established that the realization of the tasks took place according to the following scheme: stage 1 – educational activity aimed at the formation of hygienic culture, healthy lifestyle; 2 – acquaintance with the technologies of protection, preservation and promotion of health (rules of hygiene and sanitation, regime of the day, nutrition), aimed at forming the resistance of the organism to adverse environmental factors; 3 – physical activity as a health advantage, for children it includes games, sports, exercise, hiking, competitions, dancing, recreation or work, etc .; 4 – fight against bad habits.Доведено, що виховання здорового способу життя молодших школярів відбувалося через інформування, навчальну та власне виховну діяльність, спрямовану на формування санітарно-гігієнічної культури, здорового способу життя, вироблення корисних звичок (дотримання режиму дня, правильного способу харчування, рухової активності) та профілактику шкідливих звичок (куріння, вживання алкоголю тощо). Мета нашої статті полягає у виявленні традиції виховання здорового способу життя дітей молодшого шкільного віку; аналізі змісту шкільних підручників, які використовувались у народних школах Закарпаття міжвоєнного періоду на вміст матеріалів про підтримку і зміцнення здоров’я. Основні результати дослідження  полягають в окресленні можливостей виховання здорового способу життя у змісті початкової освіти та віддзеркаленні їх у предметі «Горожанська наука і виховання» (громадянознавство). Встановлено, що реалізація завдань відбувалася за такою схемою: 1 етап ‒ освітня діяльність, спрямована на формування гігієнічної культури, здорового способу життя; 2 ‒ ознайомлення із технологіями захисту, збереження і зміцнення здоров’я (правила гігієни та санітарії, режим дня, харчування), спрямованими на формування стійкості організму до несприятливих факторів навколишнього середовища; 3 ‒ фізична активність як перевага здоров’я, для дітей охоплює ігри, спорт, фізичні вправи, походи, змагання, танці, активний відпочинок або працю тощо; 4 – боротьба зі шкідливими звичками

Magnetospheric particle acceleration and X-ray emission of pulsars

The available data on isolated X-ray pulsars, their wind nebulae, and the supernova remnants which are connected to some of these sources are analyzed. It is shown that electric fields of neutron stars tear off charged particles from the surface of neutron star and trigger the acceleration of particles. The charged particles are accelerated mainly in the field of magneto-dipole radiation wave. Power and energy spectra of the charged particles depend on the strength of the magneto-dipole radiation. Therefore, the X-ray radiation is strongly dependent on the rate of rotational energy loss and weakly dependent on the electric field intensity. Coulomb interaction between the charged particles is the main factor for the energy loss and the X-ray spectra of the charged particles.Comment: minor correction on table format, 20 pages (4 figures, 1 table), submitted to International Journal of Modern Physics

Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based on a B-decay model

Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most heavily examined isolated neutron stars. Wide absorption lines were observed in its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These absorption lines can be interpreted as a principal frequency centered at 0.7 keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can be formed by resonant proton cyclotron scattering leading to a magnetic field which is two orders of magnitude larger than the perpendicular component of the surface dipole magnetic field (B) found from the rotation period (P) and the time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides, age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to 1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age ($\tau$=P/2\.{P}) of the neutron star. These huge differences between the magnetic field values and the ages can be explained based on a B-decay model. If the decay is assumed to be exponential, the characteristic decay time turns out to be several thousand years which is three orders of magnitude smaller than the characteristic decay time of radio pulsars represented in an earlier work. The lack of detection of radio emission from DRQNSs and the lack of point sources and pulsar wind nebulae in most of the observed SNRs can also be partly explained by such a very rapid exponential decay. The large difference between the characteristic decay times of DRQNSs and radio pulsars must be related to the differences in the magnetic fields, equation of states and masses of these isolated neutron stars.Comment: 13 pages, 1 figur

The state of the art in evaluating the performance of department chairs and division heads.

This study explores the little understood process of evaluating the performance of department chairs/division heads in dental schools. Specifically, this research aimed to elucidate the methods, processes, and outcomes related to the job performance of department chairs/division heads. Forty-three deans and 306 chairs completed surveys with both close-ended and open-ended questions. In addition, ten deans and ten chairs were interviewed. Results indicate that 80 to 90 percent of department chairs are formally evaluated, although as many as 50 percent may lack job descriptions. Recommended best practices for performance appraisal--such as having at least yearly appraisals, holding face-to-face meetings, and setting specific, personal performance objectives/benchmarks for chairs--are being used in most schools. Still, there is much room to improve appraisals by incorporating other recommended practices. Overall high levels of satisfaction were reported by both chairs and deans for the process and outcomes of appraisals. Qualitative data showed some convergence of opinions about appraisals with the notable exception of informal feedback. We explore some implications of these results, especially as they relate to improving performance appraisals

Strategic management and organizational behavior in dental education: reflections on key issues in an environment of change.

With issues such as shrinking revenue, access to care, faculty workloads, and graying faculty, dental schools are faced with difficult challenges that fall to dental school deans to manage. Do dental school deans have the organizational skill sets and ethical frameworks necessary to address the challenges now facing dental schools? The purpose of this article is to pose questions and suggestions regarding some of the key issues in dental colleges today and to stimulate discussion in the dental community about needed changes in dental education

The state of the art in evaluating the performance of assistant and associate deans as seen by deans and assistant and associate deans.

This study explores the little-understood process of evaluating the performance of assistant and associate deans at dental colleges in the United States and Canada. Specifically, this research aimed to identify the methods, processes, and outcomes related to the performance appraisals of assistant/associate deans. Both deans and assistant/associate deans were surveyed. Forty-four of sixty-six deans (66.7 percent) and 227 of 315 assistant/associate deans (72.1 percent) completed surveys with both close-ended and open-ended questions. In addition, ten individuals from each group were interviewed. Results indicate that 75-89 percent of assistant/associate deans are formally evaluated, although as many as 27 percent may lack formal job descriptions. Some recommended best practices for performance appraisal are being used in a majority of colleges. Examples of these best practices are having at least yearly appraisals, holding face-to-face meetings, and setting specific, personal performance objectives/benchmarks for assistant/associate deans. Still, there is much room to improve appraisals by incorporating other recommended practices. Relatively high levels of overall satisfaction were reported by both assistant/associate deans and deans for the process and outcomes of appraisals. Assistant/associate deans rated the value of appraisals to overall development lower than did deans. Qualitative data revealed definite opinions about what constitutes effective and ineffective appraisals, including the use of goal-setting, timeliness, and necessary commitment. Several critical issues related to the results are discussed: differences in perspectives on performance reviews, the importance of informal feedback and job descriptions, the influence of an assistant/associate deans\u27 lack of tenure, and the length of service of deans. Lastly, recommendations for enhancing performance evaluations are offered

Erratum: Reducing Cascading Failure Risk by Increasing Infrastructure Network Interdependence

This corrects the article DOI: 10.1038/srep44499

Stability of Scalar Fields in Warped Extra Dimensions

This work sets up a general theoretical framework to study stability of models with a warped extra dimension where N scalar fields couple minimally to gravity. Our analysis encompasses Randall-Sundrum models with branes and bulk scalars, and general domain-wall models. We derive the Schrodinger equation governing the spin-0 spectrum of perturbations of such a system. This result is specialized to potentials generated using fake supergravity, and we show that models without branes are free of tachyonic modes. Turning to the existence of zero modes, we prove a criterion which relates the number of normalizable zero modes to the parities of the scalar fields. Constructions with definite parity and only odd scalars are shown to be free of zero modes and are hence perturbatively stable. We give two explicit examples of domain-wall models with a soft wall, one which admits a zero mode and one which does not. The latter is an example of a model that stabilizes a compact extra dimension using only bulk scalars and does not require dynamical branes.Comment: 25 pages, 2 figures; v2: minor changes to text, references added, matches published versio

Stable, Ductile and Strong Ultrafine HT-9 Steels via Large Strain Machining

Beyond the current commercial materials, refining the grain size is among the proposed strategies to manufacture resilient materials for industrial applications demanding high resistance to severe environments. Here, large strain machining (LSM) was used to manufacture nanostructured HT-9 steel with enhanced thermal stability, mechanical properties, and ductility. Nanocrystalline HT-9 steels with different aspect rations are achieved. In-situ transmission electron microscopy annealing experiments demonstrated that the nanocrystalline grains have excellent thermal stability up to 700 & DEG;C with no additional elemental segregation on the grain boundaries other than the initial carbides, attributing the thermal stability of the LSM materials to the low dislocation densities and strains in the final microstructure. Nano-indentation and micro-tensile testing performed on the LSM material pre- and post-annealing demonstrated the possibility of tuning the material's strength and ductility. The results expound on the possibility of manufacturing controlled nanocrystalline materials via a scalable and cost-effective method, albeit with additional fundamental understanding of the resultant morphology dependence on the LSM conditions