445 research outputs found

    Renormalization group analysis of the three-dimensional Gross-Neveu model at finite temperature and density

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    The Renormalization Group flow equations obtained by means of a proper time regulator are used to analyze the restoration of the discrete chiral symmetry at non-zero density and temperature in the Gross-Neveu model in d=2+1 dimensions. The effects of the wave function renormalization of the auxiliary scalar field on the transition have been studied. The analysis is performed for a number of fermion flavors N_f=12 and the limit of large N_f is also considered. The results are compared with those coming from lattice simulations.Comment: Latex file, 12 pages, 2 eps figures, minor changes, added references, published versio

    Extended radio emission in BL Lac objects - I: the images

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    We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope (WSRT) at 1.40 GHz. In this paper we present high sensitivity images at arcsecond resolution of the 18 objects showing extended structure in our images, and of another source from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey (Becker et al. 1995). In general our high sensitivity images reveal an amount of extended emission larger than previously reported. In some objects the luminosity of the extended structure is comparable with that of FR~II radio sources. A future paper will be devoted to the interpretation of these results.Comment: 12 pages, 35 figures, to appear on A&A Supp. Ser., postscript file with figures included available at http://www.ira.noto.cnr.it/staff/carlo/ds1030.ps.g

    Motivations for volunteerism, satisfaction, and emotional exhaustion: The moderating effect of volunteers' age

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    This investigation aims to explore the moderating role of volunteers' age in the relation between motivations for volunteering and, respectively, satisfaction with volunteerism and emotional exhaustion. A longitudinal study was conducted with a sample of 241 Spanish healthcare volunteers. Results show that volunteers' age moderates the relations between social motivations and satisfaction, and social motivations and volunteers' emotional exhaustion, and also between growth motivations and satisfaction, and volunteers' emotional exhaustion. The relationships between security motivations and satisfaction and emotional exhaustion are not moderated by age. Our findings underline that, for younger volunteers, satisfaction decreases when social motives are high, rather than low, and, in the opposite, emotional exhaustion increases when growth motives are high, rather than low. For older volunteers, instead, the only significant effect concern satisfaction, which is higher when social motives are high, rather than low

    Detection of Contact Binaries Using Sparse High Phase Angle Lightcurves

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    We show that candidate contact binary asteroids can be efficiently identified from sparsely sampled photometry taken at phase angles >60deg. At high phase angle, close/contact binary systems produce distinctive lightcurves that spend most of the time at maximum or minimum (typically >1mag apart) brightness with relatively fast transitions between the two. This means that a few (~5) sparse observations will suffice to measure the large range of variation and identify candidate contact binary systems. This finding can be used in the context of all-sky surveys to constrain the fraction of contact binary near-Earth objects. High phase angle lightcurve data can also reveal the absolute sense of the spin.Comment: 4 pages, 4 figures, 1 table. Accepted for publication in ApJ

    Are Botanical Biopesticides Safe for Bees (Hymenoptera, Apoidea)?

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    The recent global decline in insect populations is of particular concern for pollinators. Wild and managed bees (Hymenoptera, Apoidea) are of primary environmental and economic importance because of their role in pollinating cultivated and wild plants, and synthetic pesticides are among the major factors contributing to their decline. Botanical biopesticides may be a viable alternative to synthetic pesticides in plant defence due to their high selectivity and short environmental persistence. In recent years, scientific progress has been made to improve the development and effectiveness of these products. However, knowledge regarding their adverse effects on the environment and non-target species is still scarce, especially when compared to that of synthetic products. Here, we summarize the studies concerning the toxicity of botanical biopesticides on the different groups of social and solitary bees. We highlight the lethal and sublethal effects of these products on bees, the lack of a uniform protocol to assess the risks of biopesticides on pollinators, and the scarcity of studies on specific groups of bees, such as the large and diverse group of solitary bees. Results show that botanical biopesticides cause lethal effects and a large number of sublethal effects on bees. However, the toxicity is limited when comparing the effects of these compounds with those of synthetic compounds

    SiPM and front-end electronics development for Cherenkov light detection

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    The Italian Institute of Nuclear Physics (INFN) is involved in the development of a demonstrator for a SiPM-based camera for the Cherenkov Telescope Array (CTA) experiment, with a pixel size of 6Ă—\times6 mm2^2. The camera houses about two thousands electronics channels and is both light and compact. In this framework, a R&D program for the development of SiPMs suitable for Cherenkov light detection (so called NUV SiPMs) is ongoing. Different photosensors have been produced at Fondazione Bruno Kessler (FBK), with different micro-cell dimensions and fill factors, in different geometrical arrangements. At the same time, INFN is developing front-end electronics based on the waveform sampling technique optimized for the new NUV SiPM. Measurements on 1Ă—\times1 mm2^2, 3Ă—\times3 mm2^2, and 6Ă—\times6 mm2^2 NUV SiPMs coupled to the front-end electronics are presentedComment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

    Current Approaches, Typologies and Predictors of Deviant Work Behaviors: A Scoping Review of Reviews

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    This study provides a scoping review of the recent conceptual developments about the deviant work behavior and counterproductive work behavior constructs. It also examines the specific types of deviant work behavior that have been more consistently investigated in the last decade, and whether they cover the interpersonal or organizational type of deviant behavior. In addition, individual, group, and organizational predictors of deviant work behaviors are examined. A scoping review of reviews was conducted on Scopus and Web of Science databases and 54 studies published from 2010 to June 2021 were taken into account. Results show that more recent conceptualizations are based on well established models in the literature and consider the hierarchical structure of these two constructs. Recent reviews examine the relationships of deviant work behavior with job performance and ethical behavior constructs, the multilevel nature of deviant work behavior, and the consequences for the actor of the deviance. The specific types of deviant work behavior more frequently reviewed in the last decade are workplace abuse, incivility, ostracism, bullying and sexual harassment, and abusive and destructive leadership; this evidence suggests a much greater attention to interpersonal, rather than organizational, forms of deviant work behavior. Regarding antecedents, results show the continuing prevalence of personality factors antecedents. Limitations of the study and theoretical and practical implications for the field are also provided
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