Magicity of the 52^{52}Ca and 54^{54}Ca isotopes and tensor contribution within a mean--field approach

We investigate the magicity of the isotopes $^{52}$Ca and $^{54}$Ca, that was recently confirmed by two experimental measurements, and relate it to like--particle and neutron--proton tensor effects within a mean--field description. By analyzing Ca isotopes, we show that the like--particle tensor contribution induces shell effects that render these nuclei more magic than they would be predicted by neglecting it. In particular, such induced shell effects are stronger in the nucleus $^{52}$Ca and the single--particle gaps are increased in both isotopes due to the tensor force. By studying $N=32$ and $N=34$ isotones, neutron--proton tensor effects may be isolated and their role analyzed. It is shown that neutron--proton tensor effects lead to increasing $N=32$ and $N=34$ gaps, when going along isotonic chains, from $^{58}$Fe to $^{52}$Ca, and from $^{60}$Fe to $^{54}$Ca, respectively. The mean--field calculations are perfomed by employing one Skyrme parameter set, that was introduced in a previous work by fitting the tensor parameters together with the spin--orbit strength. The signs and the values of the tensor strengths are thus checked within this specific application. The obtained results indicate that the employed parameter set, even if generated with a partial adjustment of the parameters of the force, leads to the correct shell behavior and provides, in particular, a description of the magicity of $^{52}$Ca and $^{54}$Ca within a pure mean--field picture with the effective two--body Skyrme interaction.Comment: 7 figure

The Metaphysics of Free Will: A Critique of Free Won’t as Double Prevention

The problem of free will is deeply linked with the causal relevance of mental events. The causal exclusion argument claims that, in order to be causally relevant, mental events must be identical to physical events. However, Gibb has recently criticized it, suggesting that mental events are causally relevant as double preventers. For Gibb, mental events enable physical effects to take place by preventing other mental events from preventing a behaviour to take place. The role of mental double preventers is hence similar to what Libet names free won’t, namely the ability to veto an action initiated unconsciously by the brain. In this paper I will propose an argument against Gibb’s account, the causal irrelevance argument, showing that Gibb’s proposal does not overcome the objection of systematic overdetermination of causal relevance, because mental double preventers systematically overdetermine physical double preventers, and therefore mental events are causally irrelevant

Primordial Magnetic Fields and Electroweak Baryogenesis

In this contribution we will shortly review the main mechanism through which primordial magnetic fields may affect the electroweak baryogenesis. It is shown that although strong magnetic fields might enhance the strength of the electroweak phase transition, no benefit is found for baryogenesis once the effect of the field on the sphaleron rate is taken into account. The possible role of hypermagnetic helicity for the electroweak baryogenesis is shortly discussed.Comment: 10 pages, 1 fig. Plenary talk presented at the COSMO99 Conference, Trieste, Italy, 27 Sept - 3 Oct, 199

Reactant pressure differential control for fuel cell gases

A pair of spool valves are described which are balanced between pressures of reactant gases supplied to a fuel cell power plant. The pressure differences are controlled between the gases so as to maintain those pressures substantially in the proportions necessary for operation of the fuel cell

Globalization of Capital Markets

Speech given at Session 1: The Global Capital Market: What\u27s Next. Richard Grasso spoke about the exciting changes that are transforming the global capital markets, particularly as seen from the perspective of 11 Wall Street. He also gave a brief review of some statistics, from markets past and present to show how dramatic these changes have been

Importance of Lipid Composition in the Membrane Dynamics of Urothelial Umbrella Cells

The studies on membrane dynamics in urinary bladder umbrella cells were focused on proteins as important factors for maintaining the permeability barrier and their role as pathways modulators for the discoidal/fusiform endocytic vesicles which is one of the main features of the umbrella cells. However, our workgroup has dedicated to the study of lipid membrane composition and its biological impact in the urothelium. We first studied the lipid membrane composition of rat urothelium modified my dietary treatments differentiated in their fatty acid composition. Changes of lipid composition were related to the asymmetric unit membrane organization and permeability. Finally, we observed that the lipid composition was critically related to the intracellular pathways of discoidal/fusiform endocytic vesicles and their content. The purpose of this communication is to summarize the importance of lipids in the membrane organization and permeability of the apical plasma membrane and endocytic vesicles of umbrella cells.Fil: Grasso, Ernesto Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Química Biológica de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Centro de Investigaciones en Química Biológica de Córdoba; Argentin

A dynamic operationalization of Sen's capability approach

The limits of the utilitarian approach have led to a search for different notions of welfare. The income approach to well-being, in fact, doesn’t account for the diversity in human beings and for the heterogeneities of contingent circumstances. Amartya Sen, looking for broader notions of well-being, has developed an approach focused on the freedom of individuals to pursue their own project of life: the capability approach. The main purpose of the paper is to explore the possibility of using system dynamics to operationalize Sen’s framework. First of all we address the methodological issues that have to be considered in order to operationalize the capability approach in a dynamic framework. Then we investigate the architecture of the three- functionings model we devised to represent human well-being, as intended in the capability approach. Furthermore, we analyze in depth the structure of a particular functioning, and consider some simulations for the selected functioning and for the whole model over time. Finally, the concluding remarks suggest some indications about the use of system dynamics in order to operationalize the capability approach, and consider the main findings derived from the simulations carried out.welfare measurement

Climate change: the global public good

Climate change is the exemplary global public good, because each country’s emissions of greenhouse gases contribute cumulatively to the increase of the overall concentration, and each country’s abatements entail higher cost than benefit, unless effective concerted collective actions take place. Unfortunately there are weak political and economic instruments for entering a climate agreement and for attaining and maintaining its goals. Moreover there are strong free-riding incentives since it is quite difficult - and indeed very unpopular - for governments to convince people to give up part of their current wealth for the sake of uncertain gains in the future, maybe accruing to population in remote distance. In this paper I deal with the main issues put forward by the global public good nature of climate change. Namely, I firstly shed some light on the economics of global warming in order to point out a benefit-cost framework suitable for quantifying its impacts. Then, I analyse the determinants of the provision of climate stability and the international collective action that should be undertaken to compel sovereign countries to enter into a climate agreement. Hence, after outlining the most important approach to international cooperation, I consider the possibility of a coalition formation according to the game theoretic perspective, the interests determining the participation in international agreements, and the possible sanctions imposable to countries that refuse to comply with an international climate agreement.climate change, public goods, international environmental agreements