5,152 research outputs found
New insights on accretion in Supergiant Fast X-ray Transients from XMM-Newton and INTEGRAL observations of IGR J175442619
XMM-Newton observations of the supergiant fast X-ray transient
IGRJ175442619 are reported and placed in the context of an analysis of
archival INTEGRAL/IBIS data that provides a refined estimate of the orbital
period at 4.92720.0004 days. A complete outburst history across the
INTEGRAL mission is reported. Although the new XMM-Newton observations (each
lasting 15 ks) targeted the peak flux in the phase-folded hard X-ray
light curve of IGRJ175442619, no bright outbursts were observed, the
source spending the majority of the exposure at intermediate luminosities of
the order of several 10ergs (0.510keV) and
displaying only low level flickering activity. For the final portion of the
exposure, the luminosity of IGRJ175442619 dropped to
410ergs (0.5 - 10 keV), comparable with the
lowest luminosities ever detected from this source, despite the observations
being taken near to periastron. We consider the possible orbital geometry of
IGRJ175442619 and the implications for the nature of the mass transfer
and accretion mechanisms for both IGRJ175442619 and the SFXT population.
We conclude that accretion under the `quasi-spherical accretion' model provides
a good description of the behaviour of IGRJ175442619, and suggest an
additional mechanism for generating outbursts based upon the mass accumulation
rate in the hot shell (atmosphere) that forms around the NS under the
quasi-spherical formulation. Hence we hope to aid in explaining the varied
outburst behaviours observed across the SFXT population with a consistent
underlying physical model.Comment: 12 pages, 5 figures, accepted for publication in MNRA
Fine and ultrafine particle number and size measurements from industrial combustion processes : primary emissions field data
This study is to our knowledge the first to present the results of on-line measurements of residual nanoparticle numbers downstream of the flue gas treatment systems of a wide variety of medium- and large-scale industrial installations. Where available, a semi-quantitative elemental composition of the sampled particles is carried out using a Scanning Electron Microscope coupled with an Energy Dispersive Spectrometer (SEM-EDS). The semi-quantitative elemental composition as a function of the particle size is presented. EU's Best Available Technology documents (BAT) show removal efficiencies of Electrostatic Precipitator (ESP) and bag filter dedusting systems exceeding 99% when expressed in terms of weight. Their efficiency decreases slightly for particles smaller than 1 mu m but when expressed in terms of weight, still exceeds 99% for bag filters and 96% for ESP. This study reveals that in terms of particle numbers, residual nanoparticles (NP) leaving the dedusting systems dominate by several orders of magnitude. In terms of weight, all installations respect their emission limit values and the contribution of NP to weight concentrations is negligible, despite their dominance in terms of numbers. Current World Health Organisation regulations are expressed in terms of PM2.5 wt concentrations and therefore do not reflect the presence or absence of a high number of NP. This study suggests that research is needed on possible additional guidelines related to NP given their possible toxicity and high potential to easily enter the blood stream when inhaled by humans
Introduction to the special section on loneliness across the life span
Copyright © The Author(s) 2021. We provide an overview of the topics included in the special section of the International Journal of Behavioral Development on Loneliness Across the Life Span. We highlight the use of a life span approach to understanding loneliness and the different methodological approaches adopted by researchers. This special issue contributes toward the development of a holistic research agenda addressing loneliness across the life course and away from a focus solely upon specific age groups such as adolescents, young adults, or older adults who have been the focus of most loneliness research until comparatively recently
Self-perception but not peer reputation of bullying victimization is associated with non-clinical psychotic experiences in adolescents
Background Bullying victimization may be linked to psychosis but only self-report measures of victimization have been used so far. This study aimed (a) to investigate the differential associations of peer-nominated versus self-reported victim status with non-clinical psychotic experiences in a sample of young adolescents, and (b) to examine whether different types of self-reported victimization predict non-clinical psychotic experiences in these adolescents. Method A combination of standard self-report and peer nomination procedures was used to assess victimization. The sample (n = 724) was divided into four groups (exclusively self-reported victims, self- and peer-reported victims, exclusively peer-reported victims, and non-victims) to test for a group effect on non-clinical psychotic experiences. The relationship between types of victimization and non-clinical psychotic experiences was examined by a regression analysis. Results Self-reported victims, along with self- and peer-reported victims, scored higher than peer-reported victims and non-victims on non-clinical psychotic experiences. Self-reports of direct relational, indirect relational and physical victimization significantly improved the prediction of non-clinical psychotic experiences whereas verbal and possession-directed victimization had no significant predictive value. Conclusions The relationship between victimization and non-clinical psychotic experiences is only present for self-reported victimization, possibly indicative of an interpretation bias. The observed discrepancy between self-report and peer-report highlights the importance of implementing a combination of both measures for future research. Copyright © Cambridge University Press 2012
A new method for comparing rankings through complex networks: Model and analysis of competitiveness of major European soccer leagues
In this paper, we show a new technique to analyze families of rankings. In particular, we focus on sports rankings and, more precisely, on soccer leagues. We consider that two teams compete when they change their relative positions in consecutive rankings. This allows to define a graph by linking teams that compete. We show how to use some structural properties of this competitivity graph to measure to what extend the teams in a league compete. These structural properties are the mean degree, the mean strength, and the clustering coefficient. We give a generalization of the Kendall's correlation coefficient to more than two rankings. We also show how to make a dynamic analysis of a league and how to compare different leagues. We apply this technique to analyze the four major European soccer leagues: Bundesliga, Italian Lega, Spanish Liga, and Premier League. We compare our results with the classical analysis of sport ranking based on measures of competitive balance.This paper was partially supported by Spanish MICINN Funds and FEDER Funds MTM2009-13848, MTM2010-16153 and MTM2010-18674, and Junta de Andalucia Funds FQM-264.Criado Herrero, R.; García González, E.; Pedroche Sánchez, F.; Romance, M. (2013). A new method for comparing rankings through complex networks: Model and analysis of competitiveness of major European soccer leagues. Chaos. 23(4):1-10. https://doi.org/10.1063/1.4826446S110234Dobson, S., & Goddard, J. (2009). The Economics of Football. doi:10.1017/cbo9780511973864Kendall, M. G., & Smith, B. B. (1939). The Problem of Rankings. The Annals of Mathematical Statistics, 10(3), 275-287. doi:10.1214/aoms/1177732186KENDALL, M. G. (1938). A NEW MEASURE OF RANK CORRELATION. Biometrika, 30(1-2), 81-93. doi:10.1093/biomet/30.1-2.81Fagin, R., Kumar, R., Mahdian, M., Sivakumar, D., & Vee, E. (2006). Comparing Partial Rankings. SIAM Journal on Discrete Mathematics, 20(3), 628-648. doi:10.1137/05063088xLegendre, P. (2005). Species associations: the Kendall coefficient of concordance revisited. Journal of Agricultural, Biological, and Environmental Statistics, 10(2), 226-245. doi:10.1198/108571105x46642Emond, E. J., & Mason, D. W. (2002). A new rank correlation coefficient with application to the consensus ranking problem. Journal of Multi-Criteria Decision Analysis, 11(1), 17-28. doi:10.1002/mcda.313Blumm, N., Ghoshal, G., Forró, Z., Schich, M., Bianconi, G., Bouchaud, J.-P., & Barabási, A.-L. (2012). Dynamics of Ranking Processes in Complex Systems. Physical Review Letters, 109(12). doi:10.1103/physrevlett.109.128701Radicchi, F. (2011). Who Is the Best Player Ever? A Complex Network Analysis of the History of Professional Tennis. PLoS ONE, 6(2), e17249. doi:10.1371/journal.pone.0017249Chartier, T. P., Kreutzer, E., Langville, A. N., & Pedings, K. E. (2011). Sensitivity and Stability of Ranking Vectors. SIAM Journal on Scientific Computing, 33(3), 1077-1102. doi:10.1137/090772745Park, J., & Newman, M. E. J. (2005). A network-based ranking system for US college football. Journal of Statistical Mechanics: Theory and Experiment, 2005(10), P10014-P10014. doi:10.1088/1742-5468/2005/10/p10014Callaghan, T., Mucha, P. J., & Porter, M. A. (2007). Random Walker Ranking for NCAA Division I-A Football. The American Mathematical Monthly, 114(9), 761-777. doi:10.1080/00029890.2007.11920469Motegi, S., & Masuda, N. (2012). A network-based dynamical ranking system for competitive sports. Scientific Reports, 2(1). doi:10.1038/srep00904Pawlowski, T., Breuer, C., & Hovemann, A. (2010). Top Clubs’ Performance and the Competitive Situation in European Domestic Football Competitions. Journal of Sports Economics, 11(2), 186-202. doi:10.1177/1527002510363100A. Feddersen and W. Maennig, “ Trends in competitive balance: Is there evidence for growing imbalance in professional sport leagues?” Hamburg contemporary economic discussions No. 01/2005, University of Hamburg, 2005.Pedroche Sánchez, F. (2010). Competitivity groups on social network sites. Mathematical and Computer Modelling, 52(7-8), 1052-1057. doi:10.1016/j.mcm.2010.02.031PEDROCHE, F. (2012). A MODEL TO CLASSIFY USERS OF SOCIAL NETWORKS BASED ON PAGERANK. International Journal of Bifurcation and Chaos, 22(07), 1250162. doi:10.1142/s0218127412501623Pedroche, F., Moreno, F., González, A., & Valencia, A. (2013). Leadership groups on Social Network Sites based on Personalized PageRank. Mathematical and Computer Modelling, 57(7-8), 1891-1896. doi:10.1016/j.mcm.2011.12.026García, E., Pedroche, F., & Romance, M. (2013). On the localization of the personalized PageRank of complex networks. Linear Algebra and its Applications, 439(3), 640-652. doi:10.1016/j.laa.2012.10.051BOCCALETTI, S., LATORA, V., MORENO, Y., CHAVEZ, M., & HWANG, D. (2006). Complex networks: Structure and dynamics. Physics Reports, 424(4-5), 175-308. doi:10.1016/j.physrep.2005.10.009Humphreys, B. R. (2002). Alternative Measures of Competitive Balance in Sports Leagues. Journal of Sports Economics, 3(2), 133-148. doi:10.1177/152700250200300203M. Kringstad, “ Competitive balance in complex professional sports leagues,” Doctoral thesis (The University of Leeds. Leeds University Business School, 2008).Owen, P. D., Ryan, M., & Weatherston, C. R. (2007). Measuring Competitive Balance in Professional Team Sports Using the Herfindahl-Hirschman Index. Review of Industrial Organization, 31(4), 289-302. doi:10.1007/s11151-008-9157-
A Mercury Lander Mission Concept Study for the Next Decadal Survey
Mariner 10 provided our first closeup reconnaissance of Mercury during its three flybys in 1974 and 1975. MESSENGERs 20112015 orbital investigation enabled numerous discoveries, several of which led to substantial or complete changes in our fundamental understanding of the planet. Among these were the unanticipated, widespread presence of volatile elements (e.g., Na, K, S); a surface with extremely low Fe abundance whose darkening agent is likely C; a previously unknown landformhollows that may form by volatile sublimation from within rocks exposed to the harsh conditions on the surface; a history of expansive effusive and explosive volcanism; substantial radial contraction of the planet from interior cooling; offset of the dipole moment of the internal magnetic field northward from the geographic equator by ~20% of the planets radius; crustal magnetization, attributed at least in part to an ancient field; unexpected seasonal variability and relationships among exospheric species and processes; and the presence in permanently shadowed polar terrain of water ice and other volatile materials, likely to include complex organic compounds. Mercurys highly chemically reduced and unexpectedly volatile-rich composition is unique among the terrestrial planets and was not predicted by earlier hypotheses for the planets origin. As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of the Solar System and how planets (and exoplanets) form and evolve in close proximity to their host stars. The BepiColombo mission promises to expand our knowledge of this planet and to shed light on some of the mysteries revealed by the MESSENGER mission. However, several fundamental science questions raised by MESSENGERs pioneering exploration of Mercury can only be answered with in situ measurements from the planets surface
Safety and efficacy of fluticasone propionate in the topical treatment of skin diseases
Fluticasone propionate - the first carbothioate corticosteroid - has been classified as a potent anti-inflammatory drug for dermatological use. It is available as 0.05% cream and 0.005% ointment formulations for the acute and maintenance treatment of patients with dermatological disorders such as atopic dermatitis, psoriasis and vitiligo. This glucocorticoid is characterized by high lipophilicity, high glucocorticoid receptor binding and activation, and a rapid metabolic turnover in skin. Although skin blanching following fluticasone propionate exceeds that of corticosteroids of medium strength, several clinical trials demonstrate a low potential for cutaneous and systemic side-effects, even in difficult-to-treat areas like the face, the eyelids and intertriginous areas. Even among paediatric patients with atopic dermatitis, fluticasone propionate proved to be safe and effective. These pharmacological and clinical properties are reflected by the high therapeutic index of this glucocorticoid
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