34,523 research outputs found
Collisions of Deformed Nuclei: A Path to the Far Side of the Superheavy Island
A detailed understanding of complete fusion cross sections in heavy-ion
collisions requires a consideration of the effects of the deformation of the
projectile and target. Our aim here is to show that deformation and orientation
of the colliding nuclei have a very significant effect on the fusion-barrier
height and on the compactness of the touching configuration. To facilitate
discussions of fusion configurations of deformed nuclei, we develop a
classification scheme and introduce a notation convention for these
configurations. We discuss particular deformations and orientations that lead
to compact touching configurations and to fusion-barrier heights that
correspond to fairly low excitation energies of the compound systems. Such
configurations should be the most favorable for producing superheavy elements.
We analyse a few projectile-target combinations whose deformations allow
favorable entrance-channel configurations and whose proton and neutron numbers
lead to compound systems in a part of the superheavy region where alpha
half-lives are calculated to be observable, that is, longer than 1 microsecond.Comment: 15 pages. LaTeX with iopconf.sty style file. Submitted to Nuclear
Physics A. 25 figures not included here. PostScript version with figures
available at http://t2.lanl.gov/pub/publications/publications.html or at
ftp://t2.lanl.gov/pub/publications/cd
Second order expansions of action functionals of noncommutative gauge theories
Field theory and gauge theory on noncommutative spaces have been established
as their own areas of research in recent years. The hope prevails that a
noncommutative gauge theory will deliver testable experimental predictions and
will thus be a serious candidate for an extension of the Standard Model. This
note contains the results for expanded gauge theory actions on a noncommutative
space with constant theta, up to second order, together with a discussion of
the ambiguities of the expanded theory and how they affect the action.Comment: 17 page
Optimization of the extraordinary magnetoresistance in semiconductor-metal hybrid structures for magnetic-field sensor applications
Semiconductor-metal hybrid structures can exhibit a very large geometrical
magnetoresistance effect, the so-called extraordinary magnetoresistance (EMR)
effect. In this paper, we analyze this effect by means of a model based on the
finite element method and compare our results with experimental data. In
particular, we investigate the important effect of the contact resistance
between the semiconductor and the metal on the EMR effect. Introducing
a realistic in our model we find
that at room temperature this reduces the EMR by 30% if compared to an analysis
where is not considered.Comment: 4 pages; manuscript for MSS11 conference 2003, Nara, Japa
Economic voting and economic revolutionizing? The economics of incumbency changes in European democracies and revolutionary events in the Arab World
While people in democracies can vote their government out when they are discontent with its policies, those in dictatorships cannot do so. They can only attempt to expel the dictator via mass protests or revolutions. Based on a general cause-and-effect mechanism, the author analyzes whether such mass protests are more likely when the economic situation is poor and vote outs are more likely under bad economic conditions. The empirical analysis provides evidence of economic voting in the European democracies. On the other hand, the results for the Arab World show that economic revolutionizing does not occur there. For this reason, the economics of the Arab Spring are analyzed in greater detail. It can be concluded that bad policy is punished in democracies only. Therefore, by using positive analysis, the investigation demonstrates the malfunctioning of the political market in dictatorships. -- In diesem Aufsatz wird der Zusammenhang von Abwahl- bzw. Revolutionswahrscheinlichkeit und der ökonomischen Performance untersucht. Basierend auf einem allgemeinen Ursache-Wirkungs-Mechanismus werden die Thesen abgeleitet, dass eine schlechte ökonomische Performance zwar die Abwahlwahrscheinlichkeit erhöht, nicht jedoch die Revolutionswahrscheinlichkeit, da das Zustandekommen einer Revolution davon abhängt, ob das Kollektivgutproblem gelöst werden kann. Die empirische Analyse der europäischen Demokratien zeigt, dass eine schlechte ökonomische Performance vor einem Wahltermin häufiger mit einer Abwahl als mit einer Wiederwahl einhergeht. Die Untersuchung für Revolutionen und Aufstände in der arabischen Welt dagegen zeigt, dass dort kein solcher Zusammen-hang besteht, weshalb eine genauere Betrachtung der potentiellen ökonomischen Ursachen des arabischen Frühlings erfolgt. Ausgehend von der Annahme, dass die ökonomische Performance auch ein Maß für die Qualität der Regierungsarbeit ist, liefert die Analyse ein weiteres, nicht normatives Argument für die Überlegenheit von demokratischen Systemen gegenüber nicht-demokratischen, da schlechte Regierungsführung in letzeren nicht unmittelbar bestraft wird.economic voting,revolutionary events,Arab Spring,political economy,political protest,degree of democracy,dictatorship,Revolution,Abwahl,Arabischer Frühling,Demokratie,Diktatur,Neue politische Ökonomie
EXAFS studies on the reduction of palladium(II) in X zeolites
Palladium tetraammine ion exchange into zeolite, temperature treatments under
different atmospheres, and hydrogen reduction have been studied by EXAFS at
the Pd Κ edge. Complete autoreduction is found to take place between 473 and
623 Κ under vacuum.
Α bidisperse Pd metal phase is formed which agglomerates
at the expense of the small particles upon prolonged heating at 623 Κ. In
contrast, a similar treatment under oxygen suppresses autoreduction , and the
Pd cations remain in zeolite coordination sites. Additional small amounts of
palladium oxide are observed under these conditions. If hydrogen is admitted
to the dehydrated, ionic system at 295 K. the oxygen coordination of the Pd
disappears and evidence is obtained for the formation of Pd(0) dimers that
interact with the framework via a long Pd-0 bond
Formation of the frozen core in critical Boolean Networks
We investigate numerically and analytically the formation of the frozen core
in critical random Boolean networks with biased functions. We demonstrate that
a previously used efficient algorithm for obtaining the frozen core, which
starts from the nodes with constant functions, fails when the number of inputs
per node exceeds 4. We present computer simulation data for the process of
formation of the frozen core and its robustness, and we show that several
important features of the data can be derived by using a mean-field
calculation
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