An Analysis of Urban Size and Territorial Location Effects on Employment Probabilities: The Spanish Case

The probability of being employed varies depending on several factors. Many of these are related to personal characteristics such as educational level, age, gender, or number and age of children. Nevertheless, other factors may be relevant, in particular the geographical environment. The purpose of this paper is to analyse the relevance of urban size and the position of each territory (in terms of its distance from large metropolises) for the probability of being employed in the Spanish economy. Following the set of economic regions suggested by Polése, Shearmur and Rubiera (2007 ), we try to explain the spatial patterns of employment distribution. Our results show some relevant differences between these alternative economic areas. We find that municipalities with similar sizes and located at a similar distance from a metropolis but belonging to different Autonomous Communities or provinces share similar employability patterns.     

The changing morphology and increasing deceleration of supernova 1993J in M81

Twenty consecutive Very Long Baseline Interferometry images of supernova 1993J from the time of explosion to the present show the dynamic evolution of the expanding radio shell of an exploded star. High-precision astrometry reveals that the supernova expands isotropically from its explosion center. Systematic changes in the images may reflect a pattern of anisotropies and inhomogeneities in the material left over from the progenitor star. As the shock front sweeps up the material in the surrounding medium, it is increasingly decelerated and influenced by the material. After 5 years, the supernova has slowed to half of its original expansion velocity and may have entered the early stages of the adiabatic phase common in much older supernova remnants in the Milky Way Galaxy.     

Determination of Venus Winds by Ground-Based Radio Tracking of the VEGA Balloons

A global array of 20 radio observatories was used to measure the three-dimensional position and velocity of the two meteorological balloons that were injected into the equatorial region of the Venus atmosphere near Venus midnight by the VEGA spacecraft on 11 and 15 June 1985. Initial analysis of only radial velocities indicates that each balloon was blown westward about 11,500 kilometers (8,000 kilometers on the night side) by zonal winds with a mean speed of about 70 meters per second. Excursions of the data from a model of constant zonal velocity were generally less than 3 meters per second; however, a much larger variation was evident near the end of the flight of the second balloon. Consistent systematic trends in the residuals for both balloons indicate the possibility of a solar-fixed atmospheric feature. Rapid variations in balloon velocity were often detected within a single transmission (330 seconds); however, they may represent not only atmospheric motions but also self-induced aerodynamic motions of the balloon.     

The percolation phase transition in sea Ice

Sea ice exhibits a marked transition in its fluid transport properties at a critical brine volume fraction pc of about 5 percent, or temperature Tc of about -5 degreesC for salinity of 5 parts per thousand. For temperatures warmer than Tc, brine carrying heat and nutrients can move through the ice, whereas for colder temperatures the ice is impermeable. This transition plays a key role in the geophysics, biology, and remote sensing of sea ice. Percolation theory can be used to understand this critical behavior of transport in sea ice. The similarity of sea ice microstructure to compressed powders is used to theoretically predict pc of about 5 percent.