Cuba's Economic 'Reforms': Waiting for Fidel on the Eve of the Twenty-First Century.

In this paper we provide a brief summary and evaluation of the main economic changes or 'reforms' undertaken by the Cuban government during the 1990's. The thrust of our argument is that the regime does not seem to be interested in reforms that lead to a transition to a market economy or even in the more limited goal of introducing widespread market mechanisms subservient to the needs of the communist party as in China. Instead, their policies seem directed at generating mechanisms for the appropriation of foreign exchange by members of the nomenclature while keeping most citizens deprived of independent access to wealth creation activities. We develop our argument by looking separately at 'reforms' in two type of markets: those in which transactions are self-enforcing and those which depend on the contract enforcement mechanisms or services usually associated with market augmenting government to enforce transactions.Cuba, Reforms, Transition, Markets, Self-enforcing Transactions, Market Augmenting Government

Breakup of meteoroids in the Venusian atmosphere and its effects on crater formation

Early results of the Magellan mission to Venus show that almost all of the observed impact craters appear to be unaffected by erosion, burial, and tectonic deformation. Therefore it is reasonable to assume that the observed paucity of small craters in the cumulative size-frequency distribution (SFD) relative to the simple power laws observed on airless planets is most likely due to atmospheric effects on the incoming meteoroids. A model was developed earlier for travel and breakup of a meteoroid in an atmosphere, but this model was never used to estimate a SFD. An attempt is made to match the cumulative SFD and the number and size distribution of multiple-floored craters and crater fields using this model

Product Differentiation and the Gains from Trade under Bertrand Duopoly

In the literature on the welfare effects of free trade under imperfect competition, one important case seems to have been overlooked and that is the Bertrand duopoly model with differentiated products. Although many authors have analysed the welfare effects of free trade under Cournot duopoly, and demonstrated the possibility of losses from trade, there has been no thorough analysis of the welfare effects of free trade under Bertrand duopoly. This paper presents a thorough analysis of the welfare effects of free trade under Bertrand duopoly with differentiated products, and it is shown that there are always gains from trade.gains from trade, Bertrand Oligopoly

Groupoid normalisers of tensor products: infinite von Neumann algebras

The groupoid normalisers of a unital inclusion $B\subseteq M$ of von Neumann algebras consist of the set $\mathcal{GN}_M(B)$ of partial isometries $v\in M$ with $vBv^*\subseteq B$ and $v^*Bv\subseteq B$. Given two unital inclusions $B_i\subseteq M_i$ of von Neumann algebras, we examine groupoid normalisers for the tensor product inclusion $B_1\ \overline{\otimes}\ B_2\subseteq M_1\ \overline{\otimes}\ M_2$establishing the formula$$ \mathcal{GN}_{M_1\,\overline{\otimes}\,M_2}(B_1\ \overline{\otimes}\ B_2)''=\mathcal{GN}_{M_1}(B_1)''\ \overline{\otimes}\ \mathcal{GN}_{M_2}(B_2)'' $$ when one inclusion has a discrete relative commutant $B_1'\cap M_1$ equal to the centre of $B_1$ (no assumption is made on the second inclusion). This result also holds when one inclusion is a generator masa in a free group factor. We also examine when a unitary $u\in M_1\ \overline{\otimes}\ M_2$ normalising a tensor product $B_1\ \overline{\otimes}\ B_2$ of irreducible subfactors factorises as $w(v_1\otimes v_2)$ (for some unitary $w\in B_1\ \overline{\otimes}\ B_2$and normalisers$v_i\in\mathcal{N}_{M_i}(B_i)$). We obtain a positive result when one of the$M_i$is finite or both of the$B_i$are infinite. For the remaining case, we characterise the II$_1$factors$B_1$for which such factorisations always occur (for all$M_1, B_2$and$M_2$) as those with a trivial fundamental group.Comment: 22 page

Spatial analysis of IRAS observations of nearby spirals

The unbiased survey of the infrared sky carried out by the Infrared Astronomy Satellite (IRAS) satellite has greatly accelerated advances in understanding the dust component of our own and external galaxies. However, most extragalactic studies to date have been based on the IRAS Point Source Catalog (PSC), which has two serious limitations. First, in sources where a significant fraction of the flux is extended, significant errors may result from using PSC fluxes in comparative studies, and these errors could be systematic if the tendency to be non-pointlike depends on physical properties of the galaxy. Additionally, use of PSC fluxes rules out any direct investigation of the spatial distribution of the IRAS emission from disks in external galaxies. Since work on the Galactic IRAS results has shown that very different physical processes can make varying contributions to the observed flux, it is important to look at a wide sample of galaxies with some spatial resolution to study the relative dominance of these processes under a variety of conditions. Here, researchers report on work they are doing to carry out this program for many nearby spirals, using an analysis package that was developed for this purpose. Researchers carried out analysis for a sample of 121 nearby spirals. The fraction of the flux contained in a point source varies from 0 to 1 across the sample, all of which are well resolved at their nominal optical diameters. There is no evidence that the galaxies of smaller angular size are less likely to be resolved by IRAS at this level. The program gives results which are quite repeatable from scan to scan; the fraction f (point source flux over total flux) at 60 microns has typical errors of 0.03 when different scans are combined. Approximately two-thirds of the sample have more flux in the extended than in the nuclear component. There is a tendency for earlier-type spirals to be less centrally concentrated, but this effect is slight and the degree of variation is large for all types. Barred spirals are also found across the spectrum of f, but are much more likely to have little or no nuclear emission