21,083 research outputs found

    Trophonella (Gastropoda: Muricidae), a New Genus from Antarctic Waters, with the Description of a New Species

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    The new genus Trophonella is described from the outer shelf and upper continental slope of Antarcticaand islands within the Antarctic Convergence. Four previously known species that had been attributed to the genusTrophon (Trophon scotianus Powell, 1951; T. echinolamellatus Powell, 1951; T. enderbyensis Powell, 1958; and T.eversoni Houart, 1997) are included in Trophonella, as is one new species (Trophonella rugosolamellata) describedherein. Trophonella resembles Trophon in gross shell morphology: the members of both genera have large, globoseshells, paucispiral protoconchs, prominent axial lamellae, and short siphonal canals. Trophonella differs fromTrophon in having shells with evenly rounded whorls that lack a well-defined shoulder; rachidian teeth withdistinctive, broadly triangular central cusps, but that lack the marginal cusps of Trophon; characteristic sphericalaccessory salivary glands; and a circumpapillar fold on the penis that is absent in Trophon. Relationships of thegenera Trophon and Trophonella, as well as of the subfamily Trophoninae are reexamined by supplementing the datamatrix of Kool (1993b, Table 3) with data for additional taxa. Results support the segregation of Trophonella fromTrophon at the generic level. Based on the relationships of the type species of their respective nominotypical genera,Trophoninae is either the sister taxon of a narrowly circumscribed Ocenebrinae, or both are part of a larger clade. Abetter resolved phylogeny containing a much broader sampling of the more than 50 genus-level taxa that have beenattributed to these two subfamilies will be required in order to delineate more precisely the membership of the cladeand to identify its diagnostic synapomorphies.Fil: Harasewych, M. G.. National Museum of Natural History; Estados UnidosFil: Pastorino, Roberto Santiago Guido. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

    Dynamics of the Peccei Quinn Scale

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    Invoking the Peccei-Quinn (PQ) solution to the strong CP problem substitutes the puzzle of why θqcd\theta_{qcd} is so small with the puzzle of why the PQ symmetry is of such high quality. Cosmological and astrophysical considerations raise further puzzles. This paper explores this issues in several contexts: string theory and field theory, and theories without and with low energy supersymmetry. Among the questions studied are whether requiring axion dark matter can account for the quality of the PQ symmetry, to which the answer is sometimes yes. In non-supersymmetric theories, we find fa=1012f_a = 10^{12} GeV is quite plausible. In gauge mediation, cosmological constraints on pseudomoduli place faf_a in this range, and require that the gravitino mass be of order an MeV.Comment: 17 pages, 1 figur

    Economic growth and corporate renewal

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    To address competition from Emerging and Industrialized Countries it is necessary for Italian companies to face structural and financial reforms. Structural reforms will affect and improve processes, products. They will upgrade knowledge transfer. At the same time, financial reforms are necessary to adjust firms’ dimensions with what markets and international competition require. A movement in the right direction is the rise of innovative medium firms. These corporations are spreading through affiliation networks which improve the systemic efficiency and that are responsible for the progressive deep changes in the industry. Italy’s growth strategy will call for appropriate industrial policies and supported by a widespread socioeconomic consensus.internationalization, technological change, international trade, emerging countries.

    Causal Effects of Monetary Shocks: Semiparametric Conditional Independence Tests with a Multinomial Propensity Score

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    Macroeconomists have long been concerned with the causal effects of monetary policy. When the identification of causal effects is based on a selection-on-observables assumption, non-causality amounts to the conditional independence of outcomes and policy changes. This paper develops a semiparametric test for conditional independence in time series models linking a multinomial policy variable with unobserved potential outcomes. Our approach to conditional independence testing is motivated by earlier parametric tests, as in Romer and Romer (1989, 1994, 2004). The procedure developed here is semiparametric in the sense that we model the process determining the distribution of treatment – the policy propensity score – but leave the model for outcomes unspecified. A conceptual innovation is that we adapt the cross-sectional potential outcomes framework to a time series setting. This leads to a generalized definition of Sims (1980) causality. A technical contribution is the development of root-T consistent distribution-free inference methods for full conditional independence testing, appropriate for dependent data and allowing for first-step estimation of the propensity score.monetary policy, propensity score, multinomial treatments, causality
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