1,647 research outputs found

    Hard Cosmic Ray Sea in the Galactic Center: a consistent interpretation of H.E.S.S. and Fermi-LAT Îł\gamma-ray data

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    We present a novel interpretation of the gamma-ray diffuse emission measured by H.E.S.S. in the Galactic Center (GC) region and the Galactic ridge. Our starting base is an updated analysis of PASS8 Fermi-LAT data, which allows to extend down to few GeV the spectra measured by H.E.S.S. and to infer the primary CR radial distribution above 100 GeV. We compare those results with a CR transport model assuming a harder scaling of the diffusion coefficient with rigidity in the inner Galaxy. Such a behavior reproduces the radial dependence of the CR spectral index recently inferred from Fermi-LAT measurements in the inner GP. We find that, in this scenario, the bulk of the Galactic ridge emission can be naturally explained by the interaction of the diffuse, steady-state Galactic CR sea interacting with the gas present in the Central molecular zone. The evidence of a GC PeVatron is significantly weaker than that inferred adopting a conventional (softer) CR sea.Comment: Oral contribution to the International Cosmic Ray Conference (ICRC 2017), 12-20 July 2017, Bexco, Busan, Kore

    Gradual transition from insulator to semimetal of Ca1−x_{1-x}Eux_{x}B6_{6} with increasing Eu concentration

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    The local environment of Eu2+^{2+} (4f74f^{7}, S=7/2S=7/2) in Ca1−x_{1-x}Eux_{x}B6_{6} (0.003â©œxâ©œ1.000.003\leqslant x\leqslant 1.00) is investigated by means of electron spin resonance (ESR). For xâ‰Č0.003x\lesssim 0.003 the spectra show resolved \textit{fine} and \textit{hyperfine} structures due to the cubic crystal \textit{electric} field and nuclear \textit{hyperfine} field, respectively. The resonances have Lorentzian line shape, indicating an \textit{insulating} environment for the Eu2+^{2+} ions. For 0.003â‰Čxâ‰Č0.070.003\lesssim x\lesssim 0.07, as xx increases, the ESR lines broaden due to local distortions caused by the Eu/Ca ions substitution. For 0.07â‰Čxâ‰Č0.300.07\lesssim x\lesssim 0.30, the lines broaden further and the spectra gradually change from Lorentzian to Dysonian resonances, suggesting a coexistence of both \textit{insulating} and \textit{metallic} environments for the Eu2+^{2+} ions. In contrast to Ca1−x_{1-x}Gdx_{x}B6_{6}, the \textit{fine} structure is still observable up to x≈0.15x\approx 0.15. For x≳0.30x\gtrsim 0.30 the \textit{fine} and \textit{hyperfine} structures are no longer observed, the line width increases, and the line shape is purely Dysonian anticipating the \textit{semimetallic} character of EuB6_{6}. This broadening is attributed to a spin-flip scattering relaxation process due to the exchange interaction between conduction and Eu2+^{2+} 4f4f electrons. High field ESR measurements for x≳0.15x\gtrsim 0.15 reveal smaller and anisotropic line widths, which are attributed to magnetic polarons and Fermi surface effects, respectively.Comment: Submitted to PR

    Does Entrepreneurship Matter for Inclusive Growth? The Role of Social Progress Orientation

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    Building upon institutional economics, we examine how social progress orientation (SPO) affects inclusive growth through innovative and opportunity entrepreneurship. Hypotheses about civic activism, voluntary spirit, and the inclusion of minorities as proxies of SPO that affect entrepreneurship directly and inclusive growth indirectly have been suggested. Using unbalanced panel data of 132 observations (63 countries) and the three-stage least-squares method (3SLS), we provide empirical evidence that these three measures of SPO significantly affect innovative and opportunity entrepreneurship. Interestingly, our endogenous measures of entrepreneurial activity have served to explain inclusive growth, which is observed through poverty reduction across countries. Public policies should focus on social values oriented to progress in order to stimulate valuable entrepreneurial activity and hence facilitate economic development that also embraces vulnerable communities

    Attracting the Entrepreneurial Potential: A Multilevel Institutional Approach

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    The research on institutions’ role in entrepreneurship acknowledges that formal and informal institutions matter. However, previous research has stressed less the co-existence and interaction between individual- and country-level factors that shape entrepreneurial potential, population of skill-full individuals with no entrepreneurial intentions, across countries. In this study, we investigate the multilevel influence of informal institutions on entrepreneurial potential. Drawing from institutional theory and multilevel approach in a sample of 880,576 individuals for the period 2006–2016, we find that the informal country-level institutional forces compensate the lack of individual-level factors among those with low entrepreneurial potential. For instance, media coverage on entrepreneurship or education can enhance the entrepreneurial potential in its lower end. Hence, our findings provide novel evidence on the relevance and interaction of the informal institutions among potential entrepreneurs. Our findings suggest policy implications regarding educational programs to close the gap between entrepreneurially skilled non-potential and skilled potential individual

    Innovation through R&D activities in the European context: Antecedents and consequences

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    Despite the fact that the determinants and the consequences of R&D activities have been extensively studied in previous research, further efforts to integrate disparate streams of literature might bring new insights into innovation decision-making by firms. In particular, this article studies the simultaneous effects that a set of factors (at both company and environmental levels of analysis) have on R&D activity, which explain firm growth. A two-stage probit least squares (2SPLS) estimation is applied to data from the EU-EFIGE/Bruegel-UniCredit dataset for seven European countries for the years 2007-2009. The main findings show that not all the R&D determinants lead to firm growth. In particular, R&D activities are affected by the employment of a significant number of foreign executives, a higher percentage of employees with fixed-term contracts, appropriate labour regulations and access to employees who have received external training, all of which are positively related to firm growth. Based on these results, policy and practical implications to improve firms’ performances are discussed

    Site specific spin dynamics in BaFe2As2: tuning the ground state by orbital differentiation

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    The role of orbital differentiation on the emergence of superconductivity in the Fe-based superconductors remains an open question to the scientific community. In this investigation, we employ a suitable microscopic spin probe technique, namely Electron Spin Resonance (ESR), to investigate this issue on selected chemically substituted BaFe2_{2}As2_{2} single crystals. As the spin-density wave (SDW) phase is suppressed, we observe a clear increase of the Fe 3dd bands anisotropy along with their localization at the FeAs plane. Such an increase of the planar orbital content interestingly occurs independently on the chemical substitution responsible for suppressing the SDW phase. As a consequence, the magnetic fluctuations combined with the resultant particular symmetry of the Fe 3dd bands are propitious ingredients to the emergence of superconductivity in this class of materials.Comment: 6 pages, 5 figure

    Levantamento de ciclopídeos (Crustacea, Copepoda) no Brasil e avaliação preliminar de seu potencial como predadores dos vetores da dengue

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    INTRODUCTION: Cyclopid copepods are known to be good mosquito controllers, specially as regards the larvae of the dengue vectors Aedes aegypti and Ae. albopictus. MATERIAL AND METHOD: The objective of the study was to survey the local copepod fauna and search for new strains of M. longisetus var. longisetus, comparing the potential of the samples found with the current strain ML-01 against Ae. albopictus larvae, under laboratory conditions. Eleven bodies of water in Campinas, SP, Brazil, were screened for copepods by collecting 1.5 l of water from each of then. The predatory potential of adults copepods was evaluated over 24 h, in the laboratory, for groups of 5 individuals preying upon 30 first instar Ae. albopictus larvae. RESULTS AND CONCLUSION: The following cyclopid species were found: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. The predatory potential of these copepods ranged from nil to 97.3%. A sample collected in the field containing only M. longisetus var. longisetus showed the best control efficiency with no significant difference from a three-year old laboratory culture (ML-01) of the same species evaluated for comparison. The sample with few M. albidus var. albidus was ranked in second place showing an average 25.9% efficiency. The use of copepods in trap tires as dengue vector controllers is discussed.INTRODUÇÃO: CopĂ©podos ciclopĂ­deos sĂŁo conhecidos como bons controladores de mosquitos, especialmente quando considerado as larvas dos vetores da dengue Aedes aegypti e Ae. albopictus. MATERIAL E MÉTODO: Onze corpos d'ĂĄgua em Campinas, SP, Brasil, foram avaliados para copĂ©podos coletando-se 1,5 l de ĂĄgua de cada um deles. O potencial predador dos copĂ©podos adultos foi avaliado por 24 h, em laboratĂłrio, em grupos de 5 indivĂ­duos predadando sobre 30 larvas de 1° estĂĄdio de Ae. albopictus. RESULTADOS E CONCLUSÕES: No presente levantamento as seguintes espĂ©cies de ciclopĂ­deos foram encontradas: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. O potencial predador desses copĂ©podos variou de zero a 97,3%. A amostra coletada no campo contendo apenas com M. longisetus var. longisetus mostrou a melhor eficiĂȘncia de controle, sem diferença significativa de uma cultura de laboratĂłrio (ML-01) criada por 3 anos, desta mesma espĂ©cie, que foi avaliada para comparação. A amostra com poucos M. albidus var. albidus foi cotada em segundo melhor lugar, apresentando em mĂ©dia 25,9% de eficiĂȘncia. O uso de copĂ©podos em pneus armadilha como controladores dos vetores da dengue Ă© discutido.22122

    Levantamento de ciclopídeos (Crustacea, Copepoda) no Brasil e avaliação preliminar de seu potencial como predadores dos vetores da dengue

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    INTRODUCTION: Cyclopid copepods are known to be good mosquito controllers, specially as regards the larvae of the dengue vectors Aedes aegypti and Ae. albopictus. MATERIAL AND METHOD: The objective of the study was to survey the local copepod fauna and search for new strains of M. longisetus var. longisetus, comparing the potential of the samples found with the current strain ML-01 against Ae. albopictus larvae, under laboratory conditions. Eleven bodies of water in Campinas, SP, Brazil, were screened for copepods by collecting 1.5 l of water from each of then. The predatory potential of adults copepods was evaluated over 24 h, in the laboratory, for groups of 5 individuals preying upon 30 first instar Ae. albopictus larvae. RESULTS AND CONCLUSION: The following cyclopid species were found: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. The predatory potential of these copepods ranged from nil to 97.3%. A sample collected in the field containing only M. longisetus var. longisetus showed the best control efficiency with no significant difference from a three-year old laboratory culture (ML-01) of the same species evaluated for comparison. The sample with few M. albidus var. albidus was ranked in second place showing an average 25.9% efficiency. The use of copepods in trap tires as dengue vector controllers is discussed.INTRODUÇÃO: CopĂ©podos ciclopĂ­deos sĂŁo conhecidos como bons controladores de mosquitos, especialmente quando considerado as larvas dos vetores da dengue Aedes aegypti e Ae. albopictus. MATERIAL E MÉTODO: Onze corpos d'ĂĄgua em Campinas, SP, Brasil, foram avaliados para copĂ©podos coletando-se 1,5 l de ĂĄgua de cada um deles. O potencial predador dos copĂ©podos adultos foi avaliado por 24 h, em laboratĂłrio, em grupos de 5 indivĂ­duos predadando sobre 30 larvas de 1° estĂĄdio de Ae. albopictus. RESULTADOS E CONCLUSÕES: No presente levantamento as seguintes espĂ©cies de ciclopĂ­deos foram encontradas: Metacyclops mendocinus, Tropocyclops prasinus, Eucyclops sp, Eucyclops serrulatus, Eucyclops solitarius, Eucyclops ensifer, Macrocyclops albidus var. albidus and Mesocyclops longisetus var. longisetus. O potencial predador desses copĂ©podos variou de zero a 97,3%. A amostra coletada no campo contendo apenas com M. longisetus var. longisetus mostrou a melhor eficiĂȘncia de controle, sem diferença significativa de uma cultura de laboratĂłrio (ML-01) criada por 3 anos, desta mesma espĂ©cie, que foi avaliada para comparação. A amostra com poucos M. albidus var. albidus foi cotada em segundo melhor lugar, apresentando em mĂ©dia 25,9% de eficiĂȘncia. O uso de copĂ©podos em pneus armadilha como controladores dos vetores da dengue Ă© discutido

    Building Energy System Design and Planning: The Universidad de Santander Case

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    Renewable generation is gaining more thrust as the time passes, however, the growth rate of such production has been faster than the rate of the electrical grid modernization. This growth comes with great opportunities and challenges for building energy system (BES) design and planning. In this respect, this paper presents the experience and lessons learned from the design and planning of the BES of the “Universidad de Santander” (UDES) central campus. This BES renewable generation is composed of a rooftop PV system distributed across the campus buildings. The system started with 30 kWp of installed capacity (100 kWh/day on average) and now is ready to deliver near 300 kWh/day thanks to 70 kWp of extra capacity installed. In general, the implementation has been a success that now is being replied in other UDES’ campuses, and the decision taking involved highlighted the importance of a proper energy efficiency policy and electrical regulation analysis
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