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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. 相似文献
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The radiation-induced polymerization of formaldehyde has been studied in the solid state. The time of addition of one new link to a polymer chain increases exponentially in accordance with the Arrhenius law at 140 to 80 K, but approaches a constant value (approximately 10(-2) second) at temperatures below 10 K. Thus, a low-temperature limit to a chemical reaction rate has been observed. It is interpreted as a quantum effect caused by tunneling from the zero vibration level of the initial state, and a semiquantitative theory is given. The phenomenon should be taken into account for understanding tunneling of electrons in biological systems when such tunneling is accompanied by conformational changes. It could also be significant in slow, exothermic chemical reactions at low and ultralow temperatures, which may have had a role in chemical and biological evolution (cold prehistory of life?). 相似文献
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The percolation phase transition in sea Ice 总被引：1，自引：0，他引：1
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. 相似文献
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