8,483 research outputs found

    The B3-Vla CSS sample. III: Evn & Merlin images at 18 cm

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    EVN and MERLIN observations at 18 cm are presented for 18 Compact Steep--spectrum radio Sources (CSSs) from the B3-VLA CSS sample. These sources were marginally resolved in previous VLA A-configuration observations at 4.9 and 8.4 GHz or had peculiar morphologies, two of them looking like core-jets. The MERLIN images basically confirm the VLA structures at 8.4 GHz while the EVN and/or the combined images reveal several additional details.Comment: 17 pages, many low resoltion figures, A&A accepted. A higher resolution gzipped postscript file can be found at http://www.ira.cnr.it/~ddallaca/h3443.ps.g

    Longevity, fertility and Demographic Transition in an OLG model.

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    The paper investigates the effects of declining mortality on fertility and income in the standard OLG neoclassical growth model under the assumptions of accidental bequests as well as fully annuitised savings. It is shown whether and how different countries may expect increasing or decreasing fertility rates under increasing longevity, and argued that mortality decline may be another explanation of the Demographic Transition process. In particular, the fact that some countries have completed the process while others are entrapped in the second stage may depend on the initial level of mortality as well as on differences in technology and preferences. It is also argued that the third stage may not necessarily occur in some less developed countries even if their mortality rates converge towards those of industrialised countries.longevity

    Public health spending, old-age productivity and economic growth: chaotic cycles under perfect foresight

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    This paper analyses the dynamics of a double Cobb-Douglas economy with overlapping generations and public health investments that affect the supply of efficient labour of the old-aged. It is shown that the positive steady state of the economy is unique. Moreover, we provide necessary and sufficient conditions for the emergence of endogenous deterministic complex cycles when individuals are perfect foresighted. Interestingly, the equilibrium dynamics shows rather complicated phenomena such as a multiplicity of period-bubbling.OLG model; Productivity; Perfect foresight; Public health expenditure

    Profits and Competition in a Unionized Duopoly Model with Product Differentiation and Labour Decreasing Returns

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    In this paper, we aim at investigating if the conventional wisdom, that an increase of competition linked to a decrease in the degree of product differentiation always reduces firms’ profits, remains true in a unionized duopoly model with labour decreasing returns. In this context, mixed results emerge. In particular, we show that a decrease in the degree of product differentiation may affect wages, hence profits, differently, depending on both the mode of competition in the product market (Cournot or Bertrand competition) and the particular unionization structure (firm-specific or industry-wide union(s)). Interestingly, it is shown that the conventional wisdom can actually be reversed, even if under Bertrand competition only.unionized duopoly, labour decreasing returns, product differentiation, profits

    Extended emission around GPS radio sources

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    Extended radio emission detected around a sample of GHz Peaked Spectrum (GPS) radio sources is discussed. Evidence for extended emission which is related to the GPS source is found in 6 objects out of 33. Three objects are associated with quasars with core-jet pc-scale morphology, and three are identified with galaxies with symmetric (CSO) radio morphology. We conclude that the core-jet GPS quasars are likely to be beamed objects with a continuous supply of energy from the core to the kpc scale. It is also possible that low surface brightness extended radio emission is present in other GPS quasars but the emission is below our detection limit due to the high redshifts of the objects. On the other hand, the CSO/galaxies with extended large scale emission may be rejuvenated sources where the extended emission is the relic of previous activity. In general, the presence of large scale emission associated with GPS galaxies is uncommon, suggesting that in the context of the recurrent activity model, the time scale between subsequent bursts is in general longer than the radiative lifetime of the radio emission from the earlier activity.Comment: 18 paged, 18 figures, accepted for publication on A&

    Endogenous fertility and development traps with endogenous lifetime

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    We extend the literature on endogenous lifetime and economic growth by Chakraborty (2004) and Bunzel and Qiao (2005) to endogenous fertility. It is shown that development traps due to under investments in health can never appear when fertility is an economic decision variable.Endogenous fertility; Health; Life expectancy; OLG model

    A two-sector OLG economy: economic growth and demographic behaviour

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    We analyse an overlapping generations economy with two sectors of production: a capital-intensive commodity sector and a labour-intensive services sector. First, we consider an economy with exogenous population and study the effects of a change in the individual preference for old-aged services that causes a reallocation of labour between sectors on per capita income. Then, we compare the results with the standard Diamond (1965) style one-sector economy. Second, we endogenise fertility founding that a reallocation of labour in favour of the services sector causes an additional beneficial effect on per capita income with respect to the model with exogenous population. Third, we further introduce endogenous lifetime through public health investments, showing that multiple regimes of development may exist. In this context, the a rise in the preference for old-aged services may help escaping from poverty.Fertility, Life expectancy; OLG model; Public health expenditure; Services market