196 research outputs found

    Growth and social capital: an evolutionary model

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    In this paper, we analyze the role of cooperation between firms through a model of growth and social capital. In a growth model Ă  la Solow we incorporate the set of resources that a relational network has at its disposals, as a distinct production factor, and thus examine its dissemination through evolutionary type processes in firm interactions. Dynamic analysis of the model demonstrates that cooperation is able to increase the productivity of factors, fostering a higher rate of growth in the long term. The most significant result is that scarcity of social capital can produce a general collapse of the economic system in areas in which long term growth is usually sustained by the learning by doing and spillover of knowledge phenomena. This conclusion leads to reconsider the role of local development economic policies that should concentrate on activities that promote repeated interaction between firms proven to be cooperative or that encourage the formation of technological consortia.Economic growth; Social capital; Networks; Evolutionary games

    Homogeneous and inhomogeneous magnetic phases of constrained dipolar bosons

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    We study the emergence of several magnetic phases in dipolar bosonic gases subject to three-body loss mechanism employing numerical simulations based on the density matrix renormalization group(DMRG) algorithm. After mapping the original Hamiltonian in spin language, we find a strong parallelism between the bosonic theory and the spin-1 Heisenberg model with single ion anisotropy and long-range interactions. A rich phase diagram, including ferromagnetic, antiferromagnetic and non-local ordered phases, emerges in the half-filled one-dimensional case, and is preserved even in presence of a trapping potential.Comment: v2: 9 pages, 15 figures, extended version, new numerical calculations on the BKT transition, accepted for pubblication in PR

    Spontaneous Peierls dimerization and emergent bond order in one-dimensional dipolar gases

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    We investigate the effect of dipolar interactions in one-dimensional systems in connection with the possibility of observing exotic many-body effects with trapped atomic and molecular dipolar gases. By combining analytical and numerical methods, we show how the competition between short- and long-range interactions gives rise to frustrating effects which lead to the stabilization of spontaneously dimerized phases characterized by a bond ordering. This genuine quantum order is sharply distinguished from Mott and spin-density-wave phases, and can be unambiguously probed by measuring nonlocal order parameters via in situ imaging techniques

    Neural Correlates of Direct Access Trading in a Real Stock Market: An fMRI Investigation

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    Background: While financial decision making has been barely explored, no study has previously investigated the neural correlates of individual decisions made by professional traders involved in real stock market negotiations, using their own financial resources. Aim: We sought to detect how different brain areas are modulated by factors like age, expertise, psychological profile (speculative risk seeking or aversion) and, eventually, size and type (Buy/Sell) of stock negotiations, made through Direct Access Trading (DAT) platforms. Subjects and methods: Twenty male traders underwent fMRI while negotiating in the Italian stock market using their own preferred trading platform. Results: At least 20 decision events were collected during each fMRI session. Risk averse traders performed a lower number of financial transactions with respect to risk seekers, with a lower average economic value, but with a higher rate of filled proposals. Activations were observed in cortical and subcortical areas traditionally involved in decision processes, including the ventrolateral and dorsolateral prefrontal cortex (vlPFC, dlPFC), the posterior parietal cortex (PPC), the nucleus accumbens (NAcc), and dorsal striatum. Regression analysis indicated an important role of age in modulating activation of left NAcc, while traders' expertise was negatively related to activation of vlPFC. High value transactions were associated with a stronger activation of the right PPC when subjects' buy rather than sell. The success of the trading activity, based on a large number of filled transactions, was related with higher activation of vlPFC and dlPFC. Independent of chronological and professional age, traders differed in their attitude to DAT, with distinct brain activity profiles being detectable during fMRI sessions. Those subjects who described themselves as very self-confident, showed a lower or absent activation of both the caudate nucleus and the dlPFC, while more reflexive traders showed greater activation of areas involved in strategic decision making. Discussion: The neural correlates in DAT are similar to those observed in other decision making contexts. Trading is handled as a well-learned automatic behavior by expert traders; for those who mostly rely on heuristics, cognitive effort decreases, and transaction speed increases, but decision efficiency lowers following a poor involvement of the dlPFC

    Growth and social capital: an evolutionary model

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    In this paper, we analyze the role of cooperation between firms through a model of growth and social capital. In a growth model Ă  la Solow we incorporate the set of resources that a relational network has at its disposals, as a distinct production factor, and thus examine its dissemination through evolutionary type processes in firm interactions. Dynamic analysis of the model demonstrates that cooperation is able to increase the productivity of factors, fostering a higher rate of growth in the long term. The most significant result is that scarcity of social capital can produce a general collapse of the economic system in areas in which long term growth is usually sustained by the learning by doing and spillover of knowledge phenomena. This conclusion leads to reconsider the role of local development economic policies that should concentrate on activities that promote repeated interaction between firms proven to be cooperative or that encourage the formation of technological consortia

    Meissner to vortex phase transition in a two-leg ladder in artificial gauge field

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    International audienceWe consider a two-leg boson ladder in artificial gauge field with hard-core intraleg and negligible interleg interactions. Using numerical simulations based on the Density Matrix Renormalization Group (DMRG) algorithm, combined with a bosonization approach, we study its commensurate-incommensurate transition to a vortex phase at a critical flux. We discuss the finite-size scaling behavior of the longitudinal current near the transition. For weak interchain bo-son hopping, the finite size scaling is in agreement with the predictions from bosonization

    Growth and social capital: an evolutionary model

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    In this paper, we analyze the role of cooperation between firms through a model of growth and social capital. In a growth model Ă  la Solow we incorporate the set of resources that a relational network has at its disposals, as a distinct production factor, and thus examine its dissemination through evolutionary type processes in firm interactions. Dynamic analysis of the model demonstrates that cooperation is able to increase the productivity of factors, fostering a higher rate of growth in the long term. The most significant result is that scarcity of social capital can produce a general collapse of the economic system in areas in which long term growth is usually sustained by the learning by doing and spillover of knowledge phenomena. This conclusion leads to reconsider the role of local development economic policies that should concentrate on activities that promote repeated interaction between firms proven to be cooperative or that encourage the formation of technological consortia

    A Win-Win Scheme for Improving the Environmental Sustainability of University Commuters’ Mobility and Getting Environmental Credits

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    European Union Member States are called upon to meet internationally proposed environmental goals. This study is based, in particular, on the recommendation of the European Union (EU), which encourages Member States to pursue effective policies to reduce greenhouse gas (GHGs) emissions, including through appropriate changes in the behavioral habits of citizens. In this respect, among the main sectors involved, transport and mobility should certainly be mentioned. National institutions should be adequately involved in order to achieve the objectives set; in this regard, universities must certainly be considered for their educational value. These latter, for instance, could commit to improving the environmental performance of the mobility of their commuter students (to a not insignificant extent), since commuting modes are often the cause of high CO2 emissions; indeed, they still largely involve the use of internal combustion engines based on fossil fuels. In this paper, the effectiveness of a smartphone-app-based method to encourage commuter students to adopt more sustainable transport modes is evaluated. In more detail, starting from a statistical analysis of the status quo of mobility habits of a sample of students at the University of Palermo (Italy), an improvement of current habits toward a more sustainable path is encouraged through a new application (specifically created for this purpose) installed on students’ smartphones. Then, the daily and annual distances traveled by commuters with the new mobility modes are calculated, and the resulting savings in energy and CO2 emissions are estimated. Finally, it is proposed that the reduced emissions could be converted into energy-efficiency credits that the University could use to enter the emission trading system (ETS), here contextualized within the Italian “TEE” (“Energy Efficiency Credits”) scheme, while the benefits for students participating in the program could consist of reduced fees and free access to university services. The results obtained show the feasibility of the proposal. This approach can be considered a useful model that could be adopted by any other public institutions—not only universities—to facilitate their path toward decarbonization

    Human primary endothelial cells are impaired in nucleotide excision repair and sensitive to benzo[a]pyrene compared with smooth muscle cells and pericytes

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    The endothelium represents the inner cell layer of blood vessels and is supported by smooth muscle cells and pericytes, which form the vessel structure. The endothelium is involved in the pathogenesis of many diseases, including the development of atherosclerosis. Due to direct blood contact, the blood vessel endothelium is inevitably exposed to genotoxic substances that are systemically taken up by the body, including benzo[a]pyrene, which is a major genotoxic component in cigarette smoke and a common environmental mutagen and human carcinogen. Here, we evaluated the impact of benzo[a]pyrene diol epoxide (BPDE), which is the reactive metabolite of benzo[a]pyrene, on the three innermost vessel cell types. Primary human endothelial cells (HUVEC), primary human smooth muscle cells (HUASMC) and primary human pericytes (HPC) were treated with BPDE, and analyses of cytotoxicity, cellular senescence and genotoxic effects were then performed. The results showed that HUVEC were more sensitive to the cytotoxic activity of BPDE than HUASMC and HPC. We further show that HUVEC display a detraction in the repair of BPDE-induced adducts, as determined through the comet assay and the quantification of BPDE adducts in post-labelling experiments. A screening for DNA repair factors revealed that the nucleotide excision repair (NER) proteins ERCC1, XPF and ligase I were expressed at lower levels in HUVEC compared with HUASMC and HPC, which corresponds with the impaired NER-mediated removal of BPDE adducts from DNA. Taken together, the data revealed that HUVEC exhibit an unexpected DNA repair-impaired phenotype, which has implications on the response of the endothelium to genotoxicants that induce bulky DNA lesions, including the development of vascular diseases resulting from smoking and environmental pollution

    ANALISI ECONOMICA RETROSPETTIVA SULLE MISURE DI CONTENIMENTO DELLA SPESA FARMACEUTICA DELL’ASP 1 DI AGRIGENTO RELATIVE AL TRIENNIO 2010/2011/2012

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    Introduzione. Le misure di contenimento della spesa farmaceutica sono state le principali prerogative previste dal Piano di Rientro della Regione Sicilia ( adempimento A.1.2), in tal senso le realtà delle singole ASP si sono adeguate alle direttive regionali mostrando una classifica tra le Asp siciliane che vedono come protagonista virtuosa l’Asp di Agrigento, prima in classifica. La disamina dei dati fa riferimento al triennio 2010/2011/2012. Materiali e metodi. La rilevazione concerne farmaci rimborsati dal SSN ed erogati tramite canale convenzionale privato, farmaci distribuiti direttamente e quelli utilizzati in ambito ospedaliero nel triennio 2010/2011/2012, attraverso report sulla spesa farmaceutica della regione Sicilia. Risultati. Nel 2010 la spesa farmaceutica annua è stata per l’ASP 1 di Agrigento di € 102.942.864,99, questa grazie all’incremento della distribuzione diretta, di cui al PHT D.A.2205/08 attraverso l’introduzione di molecole appartenenti alla categoria N05A (l’11,03 % della spesa totale nell’anno 2011) secondi solo agli antianemici categoria B03X (26,93 % della spesa totale) già presenti nel 2010. La spesa della distribuzione diretta nel 2011 è stata di € 13.973.336,60 mentre la distribuzione attraverso le farmacie private avrebbe fatto lievitare la spesa totale a € 25.006.073,81 nel 2012 invece l’importo è stato di € 14.953.719,04 ed attraverso il canale privato convenzionato avremmo avuto un costo di € 29.530.504,13 . La spesa totale dell’Asp è passata dunque da € 102.942.864,99 nel 2010, a € 92.883.552,99 nel 2011, a € 91.128.889,13 nel 2012. Conclusioni. Le misure adottate per il contenimento della spesa hanno previsto l’introduzione a partire dal 2011 degli antipsicotici atipici, ed il potenziamento del primo ciclo di terapia per il periodo susseguente alla dimissione ospedaliera in base ai criteri dettati dal D.A. 0150/08 portando l’ASP di Ag ad essere tra le più virtuose della regione Sicilia passando dunque dalla sesta posizione in classifica nel 2010 alla prima nel 2012 con un risparmio pari al 11,48 %, il passaggio degli antipsicotici è stato dettato anche dalla necessità dei pazienti che hanno nell’essere sottoposti a controlli periodici da parte degli specialisti ma anche alla valutazione dell’appropriatezza prescrittiva che in quest’ultimo caso è affidato al farmacista ospedaliero. Un altro obiettivo dell’ASP 1 di Agrigento mirato ad un ulteriore contenimento della spesa è quello di estendere la distribuzione diretta anche alla prescrizione successiva ad ogni visita specialistica ambulatoriale
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