356 research outputs found

    Managing the boundary of an 'open' project

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    In the past ten years, the boundaries between public and open science and commercial research efforts have become more porous. Scholars have thus more critically examined ways in which these two institutional regimes intersect. Large open source software projects have also attracted commercial collaborators and now struggle to develop code in an open public environment that still protects their communal boundaries. This research applies a dynamic social network approach to understand how one community-managed software project, Debian, developed a membership process. We examine the project's face-to-face social network over a five-year period (1997-2001) to see how changes in the social structure affected the evolution of membership mechanisms and the determination of gatekeepers. While the amount and importance of a contributor's work increased the probability that a contributor would become a gatekeeper, those more central in the social network were more likely to become gatekeepers and influence the membership process. A greater understanding of the mechanisms open projects use to manage their boundaries has critical implications for research and knowledge-producing communities operating in pluralistic, open and distributed environments.open source software; social networks; organizational design; institutional design;

    L’associazione in partecipazione con apporto di lavoro dopo le recenti riforme* = The association in participation with employment after the recent reforms*. WP C.S.D.L.E. “Massimo D’Antona”.IT – 221/2014

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    This paper provides an analysis of the evolutionary legal framework regarding the contract of association in participation. Recent legislative interventions redefine the limits of working performances which can be accomplished under such contract. First of all, the A. analyses the different rebuttable presumptions introduced by Law 92/2012 with a view to avoid abusive use of association in participation as a way to escape an ordinary employment contract. Further on, the A. examines the general limits to make use of such contract as a negotiating scheme capable of including work services. At the end of the analysis the A. infers that an excessive use of restrictive rules might inhibit also “genuine” contractual relationships, where no abusive intent can be detected, thus provoking distortions in the labour market. A new regulation, based on the figure of the economically dependent self-employed worker, is finally endorsed by the Author as a way both to avoid alteration of labour law principles and to provide benefits to the whole economic system

    Subordinazione e autonomia nella disciplina delle collaborazioni organizzate dal committente

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    La tesi affronta il problema della distinzione classica tra subordinazione e autonomia, riletto alla luce dell'introduzione dell'art. 2 d.lgs. 81/2015, norma ambigua e di non facile sistemazione dogmatica. Questa disposizione si inserisce nel contesto delle tipologie lavorative in modo per piĂč versi originale ed Ăš stata oggetto di interpretazioni divergenti in dottrina. L'A. tenta di conferire alla norma una valenza sistematica, negando che possa individuare rapporti in cui rileva una coordinazione forte e viceversa identificandovi indici legali della subordinazione reinterpretati dal legislatore per aderire ai nuovi contesti produttivi

    ContinuativitĂ  e lavoro autonomo

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    Il contributo analizza la nozione di “continuatività” con riferimento al lavoro autonomo. L’Autore, dopo una premessa sulla categoria generale dei rapporti contrattuali di durata, si sofferma sulla figura delle collaborazioni coordinate e continuative e sulla ambigua nozione di occasionalità. Infine, verifica i risultati dell’analisi relazionandoli alla norma sulle collaborazioni etero-organizzate, alle misure a tutela dei lavoratori autonomi-riders che operano mediante piattaforme digitali e alle misure a tutela del lavoro autonomo non imprenditoriale.The essay analyses the notion of “continuity” with reference to self-employment. The Author, after a premise on the general category of “lasting interests’ contracts”, focuses on the figure of coordinated and continuous collaborations and on the ambiguous notion of casual work. Finally, the Author verifies the results of the analysis with reference to the norm on hetero-organized collaborations, to the measures to protect self-employed riders working via digital platforms and to the measures aimed at protecting non-entrepreneurial self-employment

    Stellar populations in the ELT perspective

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    We discuss the impact that the next generation of Extremely Large Telescopes will have on the open astrophysical problems of resolved stellar populations. In particular, we address the interplay between multiband photometry and spectroscopy.Comment: 6 pages, 3 figures. To appear in the proceedings of "EWASS 2013 Symposium 5: Local Group, Local Cosmology," (8-9 July 2013, Turku, Finland), Mem. S.A.It, M. Monelli and S. Salvadori Ed

    Improvement of skeletal muscle performance in ageing by the metabolic modulator Trimetazidine

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    BACKGROUND: The loss of muscle mass (sarcopenia) and the associated reduced muscle strength are key limiting factors for elderly people's quality of life. Improving muscle performance does not necessarily correlate with increasing muscle mass. In fact, particularly in the elderly, the main explanation for muscle weakness is a reduction of muscle quality rather than a loss of muscle mass, and the main goal to be achieved is to increase muscle strength. The effectiveness of Trimetazidine (TMZ) in preventing muscle functional impairment during ageing was assessed in our laboratory. METHODS: Aged mice received TMZ or vehicle for 12 consecutive days. Muscle function was evaluated at the end of the treatment by a grip test as well as by an inverted screen test at 0, 5, 7 and 12 days of TMZ treatment. After sacrifice, muscles were stored for myofiber cross‐sectional area assessment and myosin heavy chain expression evaluation by western blotting. RESULTS: Chronic TMZ treatment does not affect the mass of both gastrocnemius and tibialis anterior muscles, while it significantly increases muscle strength. Indeed, both latency to fall and grip force are markedly enhanced in TMZ‐treated versus untreated mice. In addition, TMZ administration results in higher expression of slow myosin heavy chain isoform and increased number of small‐sized myofibers. CONCLUSIONS: We report here some data showing that the modulation of skeletal muscle metabolism by TMZ increases muscle strength in aged mice. Reprogramming metabolism might therefore be a strategy worth to be further investigated in view of improving muscle performance in the elderly

    Bispyrene Functionalization Drives Self-Assembly of Graphite Nanoplates into Highly Efficient Heat Spreader Foils

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    Thermally conductive nanopapers fabricated from graphene and related materials are currently showing great potential in thermal management applications. However, thermal contacts between conductive plates represent the bottleneck for thermal conductivity of nanopapers prepared in the absence of a high temperature step for graphitization. In this work, the problem of ineffective thermal contacts is addressed by the use of bifunctional polyaromatic molecules designed to drive self-assembly of graphite nanoplates (GnP) and establish thermal bridges between them. To preserve the high conductivity associated to a defect-free sp2 structure, non-covalent functionalization with bispyrene compounds, synthesized on purpose with variable tethering chain length, was exploited. Pyrene terminal groups granted for a strong pi-pi interaction with graphene surface, as demonstrated by UV-Vis, fluorescence, and Raman spectroscopies. Bispyrene molecular junctions between GnP were found to control GnP organization and orientation within the nanopaper, delivering significant enhancement in both in-plane and cross-plane thermal diffusivities. Finally, nanopapers were validated as heat spreader devices for electronic components, evidencing comparable or better thermal dissipation performance than conventional Cu foil, while delivering over 90% weight reduction

    The Carina Project VII: Towards the breaking of the age-metallicity degeneracy of red giant branch stars using the c_UBI index

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    We present an analysis of photometric and spectroscopic data of the Carina dSph galaxy, testing a new approach similar to that used to disentangle multiple populations in Galactic globular clusters (GCs). We show that a proper colour combination is able to separate a significant fraction of the red giant branch (RGB) of the two main Carina populations (the old one, \sim 12 Gyr, and the intermediate-age one, 4-8 Gyr). In particular, the c_UBI=(U-B)-(B-I) pseudo-colour allows us to follow the RGB of both populations along a relevant portion of the RGB. We find that the oldest stars have more negative c_UBI pseudo-colour than intermediate-age ones. We correlate the pseudo-colour of RGB stars with their chemical properties, finding a significant trend between the iron content and the c_UBI. Stars belonging to the old population are systematically more metal poor ([Fe/H]=-2.32\pm0.08 dex) than the intermediate-age ones ([Fe/H]=-1.82\pm0.03 dex). This gives solid evidence on the chemical evolution history of this galaxy, and we have a new diagnostic that can allow us to break the age-metallicity degeneracy of H-burning advanced evolutionary phases. We compared the distribution of stars in the c_UBI plane with theoretical isochrones, finding that no satisfactory agreement can be reached with models developed in a theoretical framework based on standard heavy element distributions. Finally, we discuss possible systematic differences when compared with multiple populations in GCs.Comment: 11 pages, 11 figures, 1 table, accepted for publication in Ap

    The Carina Project. VI. The helium burning variable stars

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    We present new optical (BVI) time-series data for the evolved variable stars in the Carina dwarf spheroidal galaxy. The quality of the data and the observing strategy allowed us to identify 14 new variable stars. Eight out of the 14 are RR Lyrae (RRL) stars, four are Anomalous Cepheids (ACs) and two are geometrical variables. Comparison of the period distribution for the entire sample of RRLs with similar distributions in nearby dSphs and in the Large Magellanic Cloud indicates that the old stellar populations in these systems share similar properties. This finding is also supported by the RRL distribution in the Bailey diagram. On the other hand, the period distribution and the Bailey diagram of ACs display significant differences among the above stellar systems. This evidence suggests that the properties of intermediate-age stellar populations might be affected both by environmental effects and structural parameters. We use the BV Period--Wesenheit (PW) relation of RRLs together with evolutionary prescriptions and find a true distance modulus of 20.09+/-0.07(intrinsic)+/-0.1(statistical) mag that agrees quite well with similar estimates available in the literature. We identified four peculiar variables. Taking into account their position in the Bailey diagram and in the BV PW relation, two of them (V14, V149) appear to be candidate ACs, while two (V158, V182) might be peculiar RRLs. In particular, the variable V158 has a period and a V-band amplitude very similar to the low-mass RRL ---RRLR-02792---recently identified by Pietrzynski at al. (2012) in the Galactic bulge.Comment: Accepted for publication in ApJ, publication date September 20, 2013. 31 pages, 7 figure, 3 tables. Figs. 3 and 4 corrected, references added, minor correction
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