Cold valley

FIGURE 8.3 The collective potential energy surface of 108 and calculated within the two-center shell model by J. Maruhn et ai, shows clearly the cold valleys which reach up to the barrier and beyond. Here R is the distance between the fragments and t] = denotes the... 

The "cold valleys" in the collective potential energy surface are basic for understanding this exciting area of nuclear physics It is a master example for understanding the structure of elementary matter, which is so important for other fields, especially astrophysics, but even more so for enriching our "Weltbild," i.e., the status of our understanding of the world around us. 

The focus of this chapter is to review the latest results obtained for the excited states in the second and third minima of the potential barrier. In addition to these exotic shapes, it is also an interesting and longstanding question, at which points of the fission path the mass and energy distributions of the fission fragments are determined. Can one get different mass distributions after the fission of the super- and hyperdeformed states as suggested by Cwiok et al. (1994) What kind of clusterization is expected in these exotic nuclear states Does the predicted cold valley exist in the fission barrier These are very interesting questions but the presently available experimental information is still not sufficient to answer them. 

There are practical applications of Features 2 and 3. Balloons inflated with helium rise in the atmosphere because the molar mass of helium is substantially lower than that of air. Consequently, the density of a helium-fdled balloon is less than the density of air, and the balloon rises, just as a cork released underwater rises to the surface. Hot-air balloons exploit Feature 3. When the air beneath a hot-air balloon is heated, its density decreases, becoming smaller than the density of the outside air. With sufficient heating, the balloon rises and floats over the landscape. In contrast, cold air is less dense than warm air, so cold air sinks. For this reason, valleys often are colder than the surrounding hillsides during winter. 

The temperature patterns follow a transition from the more oceanic western area (milder temperatures) to the central depression (high temperatures in summer and intense cold and fog in winter). The northwest-southeast cold and dry wind ( cierzo ) is characteristic of the central depression of the Ebro basin, especially in spring. The cierzo at the middle Ebro valley (around Zaragoza) can lead to soil erosion and salt transport [17]. The wind intensity at this area is highly correlated with evapotranspiration [18]. A mild warm wind is sometimes occurring (especially in summer) following the opposite direction (southeast-northwest). 

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However, the MEP may be a convenient measure of the progress of a molecule in a reaction, because in general a molecule will move, on average, along the MEP in a well-defined valley, and it is a good approximation of the motion of vibrationally cold systems (e.g., for photochemical reactions in which the excited state reactant has a small/controlled amount of vibrational excess energy). 

The closed system conditions seen in cold groundwater systems may be further checked in warm springs, that is, in waters that are trapped at a depth of 1-2 km and get heated by local (normal) heat gradients. The first study of this type was done on warm springs and wells (up to 60 °Q of the Jordan Rift Valley (Mazor, 1972). The isotopic compositions of the encountered dissolved Ne, Ar, Kr, and Xe were found to be atmospheric, that is, very close (in the range of the analytical accuracy) to the values given in Table 13.2. 

Generally speaking, positive spatial autocorrelation indicates that abundances in adjacent localities are similar (aggregation) while negative-autocorrelation signifies that adjacent localities alternate between high and low values, i.e. peaks and valleys, and hot spots and cold spots. The theory and use of spatial autocorrelation procedures to analyse spatial associations has been extensively discussed (Sokal and Oden 1978a, b), and the reader is referred to these papers for more-detailed descriptions. 

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