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

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

Synchrotron Spectra and Ages of Compact Steep Spectrum Radio Sources

The high-frequency integrated spectra of Compact Steep Spectrum (CSS) sources show breaks with a moderate spectral steepening well fitted by continuous injection synchrotron spectra. In lobe-dominated CSS sources the radiative ages deduced by the synchrotron theory are in the range of up to 0.1 Myears, if equipartition magnetic fields are assumed. These radiative ages are well correlated with the source size indicating that the CSS sources are young. In order to maintain the frustration scenario, in which the sources' lifetimes are about 10 Myears, their equipartition magnetic field would be systematically decreased by a factor of more than 20. To complete the sample used in this work, we conducted observations at 230 GHz with the IRAM 30-m telescope of those sources which did not have such high-frequency observations up to now.Comment: 10 pages, 6 figures, 2 tables, accepted for publication in Astron. & Astrophys.; typos corrected; gzipped postscript version also available at: http://multivac.jb.man.ac.uk:8000/ceres/papers/papers.html http://gladia.astro.rug.nl:8000/ceres/papers/papers.htm

Economic growth and stability with public PAYG pensions and private intra-family old-age insurance

This paper compares the steady-state and dynamic outcomes of two historical alternatives as a means of old-age insurance, namely, voluntary intra-family transfers from young to old members versus pay-as-you-go public pensions, in a general equilibrium overlapping generations model with children as a desirable good. We show that the shift from a private system of old-age support to public pensions increases the gross domestic product (GDP) per worker. Moreover, although in both cases the steady-state stock of capital, under myopic expectations, may be (globally) unstable depending on the size of the inter-generational transfer, we show that the existence of public pensions rather than private intra-family gifts considerably reduces the possibility of cyclical instability

Efficient bargaining versus right to manage: a stability analysis in a Cournot duopoly with trade unions.

The present study considers a unionised (nonlinear) duopoly with two different labour market institutions, i.e. efficient bargaining (EB) and right to manage (RTM), to analyse product market stability under quantity competition with trade unions. We show that when the preference of unions towards wages is small, (i) the parametric stability region under RTM is higher than under EB, and (ii) a rise in the union power in the Nash bargaining played between firms and unions monotonically increases (resp. reduces) the parametric stability region under RTM (resp. EB). In contrast, when the preference of unions becomes larger, an increase in the union's bargaining power acts: (1) as an economic stabiliser when the union power is small; (2) as an economic de-stabiliser when the union power is high. In addition to established results with regard to equilibrium outcomes, our findings shed some light on the effects of how the labour market regulation affects out-of-equilibrium behaviours in a Cournot duopoly

PAYG pensions and economic cycles: exogenous versus endogenous fertility

In this article we compare the dynamics and long-run outcomes of an overlapping generations closed economy under exogenous and endogenous fertility. Individuals have myopic foresight, and pay-as-you-go (PAYG) public pensions exist. Although large PAYG transfers may cause endogenous fluctuations in both contexts, cyclical instability and deterministic chaos more likely occur when fertility is an economic decision variable. We find that the existence of endogenous fertility and PAYG pensions can explain the occurrence of demographic oscillations that mimic the baby boom and baby bust, in contrast with the unrealistic case of constant population, and also economic cycles. We also show that an increase in the social security contribution rate under endogenous fertility, often advocated as a remedy against the crisis of public pension budgets, may prolong both the phases and size of demographic (economic) cycles around a lower (higher) long-run level of population growth (income per worker) than under exogenous fertility

The codetermined firm in a Cournot duopoly: a stability analysis

This paper aims to study the stability issue in a Cournot duopoly with codetermined firms. We show that when both firms codetermine employment together with decentralised employees' representatives, a rise in wages acts as an economic (de)stabiliser when the wage is fairly (high) low, while under profit maximisation a rise in wages always acts as a stabilising device because the parametric stability region monotonically increases with the wage in such a case. Moreover, a rise in the union's bargaining power has a de-stabilising effect, except when the wage is low and the firm power is already high. Therefore, under codetermination a change either in the wage or firm power in the Nash bargaining plays an ambiguous role on stability. We also show with numerical simulations that complex dynamics can also occur

Public expenditure on health and private old-age insurance in an OLG growth model with endogenous fertility: chaotic dynamics under perfect foresight

This study analyses the dynamics of an economy with overlapping generations, endogenous population (fertility and adult mortality), logarithmic preferences and Cobb-Douglas technology. We show that the public provision of health investments and the existence of a private system of old-age insurance (i. e., transfers from children to parents) may cause the birth and death of multiple (three) steady states, deterministic chaos and bubbling phenomena when individuals have perfect foresight. Interestingly, however, we show that periodic dynamics (cycles) or complex dynamics (chaos) and global stability of the economy can endogenously be reconciled in the model, because the rise either in public health investments or transfers from young to old people can have the potential to smooth and ultimately suppress endogenous fluctuations in the cases of existence of both a single steady state or multiple steady states

PAYG pensions, tax-cum-subsidy and A–Pareto efficiency

An overlapping generation’s small open economy with endogenous fertility and time cost of children is analysed to show that the command optimum can be decentralised in a market setting using a PAYG transfer from the young to the old and a tax-cum-subsidy policy (i.e., a linear wage tax on labour income collected and rebated in a lump-sum way within the younger working-age generation). Indeed, the latter instrument stimulates fertility and then reduces the opportunity cost of children. Moreover, by applying the generalised notion of Pareto efficiency introduced by Golosov et al. (2007) in a context of endogenous population, some normative conclusions can be drawn: since only the utilities of those who are actually born are evaluated, we apply the concept of A-efficiency and conclude that when PAYG pensions are in existence, the tax-cum-subsidy policy can effectively be used as an alternative to the child allowance to internalise the externality of children, while also representing an A-Pareto improvement

The B3-VLA CSS sample. II: VLBA images at 18 cm

VLBA observations at 18 cm are presented for 28 Compact Steep-spectrum radio Sources (CSSs) from the B3-VLA CSS sample. These sources were unresolved in previous VLA observations at high frequencies or their brightness distribution was dominated by an unresolved steep spectrum component. More than half of them also showed a low frequency turnover in their radio spectrum. The VLBA images display in most cases a compact symmetric structure. Only in a minority of cases complex morphologies are present.Comment: 11 pages, many low resolution figures, A&A accepted. A higher quality g-zipped postscript file can be found at http://www.ira.cnr.it/~ddallaca/h3442.ps.g

A Parsec Scale Accelerating Radio Jet in the Giant Radio Galaxy NGC315

Observations of the core of the giant radio galaxy NGC315 made with VLBI interferometers are discussed in the context of a relativistic jet. The sidedness asymmetry suggests Doppler favoritism from a relativistic jet. The presence of moving features in the jet as well as jet counter--jet brightness ratios hint at an accelerating, relativistic jet. An increasing jet velocity is also supported by a comparison of the jet's observed properties with the predictions of an adiabatic expansion model. On the parsec scale, the jet is unpolarized at a wavelength of 6 cm to a very high degree in clear distinction to the high polarization seen on the kiloparsec scale.Comment: 24 pages with 8 figures. ApJ in pres