941 resultados para Absorption and emission cross-section
Measurement of the Upsilon(1S) Production Cross-Section in pp Collisions at sqrt(s) = 7 TeV in ATLAS
Resumo:
A Dutch Improved Red and White cross-breed heifer calf was evaluated for a muscular disorder resulting in exercise induced muscle stiffness. Clinical findings included generalized exercise-induced muscle spasms with normal response to muscle percussion. Electromyography showed no myotonic discharges, thus ruling out myotonia. Whereas histological examination of muscle tissue was unremarkable, Ca(2+)-ATPase activity of sarcoplasmatic reticulum membranes (SERCA1) was markedly decreased compared to control animals. Mutation analysis revealed the presence of a missense mutation in the ATP2A1 gene encoding the SERCA1 protein (p.Arg559Cys). The present case presents similarities to human Brody's disease, but also to pseudomyotonia and congenital muscular dystonia previously described in different cattle breeds.
Resumo:
Solvatochromism and thermochromism describe how a solvent or environment affects the photophysical behavior of a photoluminescent solute. The most common use of solvatochromism is as a probe in which the polarity of a solvent in which a solvatochromic solute is dissolved can be spectroscopically measured. Solvatochromic and thermochromic studies of tryptanthrin in several different solvents are reported. Absorption and corrected emission spectra for tryptanthrin at ~10-6 M concentrations are reported in four aprotic and nine alcoholic solvents. The absorption spectra are relatively unaffected by changes in solvent polarity and by differences in the hydrogen bonding ability of the alcoholic solvents. The emission spectra are much more affected by changes in solvent polarity and hydrogen bonding ability. In aprotic solvents, emission energy decreases and emission intensity increases with increasing solvent polarity. In the alcoholic solvents, emission energy also decreases with increasing solvent polarity. However, emission intensity for the alcoholic solvents varies significantly from the aprotic solvents over similar polarity ranges. This suggests that in the alcoholic solvents, hydrogen bonding ability correlates better than polarity to emission energy and intensity trends. The absorption and emission data in the aprotic solvents were also used to estimate the ground and emitting excited state dipole moments for tryptanthrin. The value obtained for the ground state dipole moment (2.37 D) agrees with theoretical results (2.06 D) and a previously reported experimental value (2.0 D). Attempts to explain previously reported results and conclusions with respect to the solvatochromic behavior of the aromatic carbonyls fluorenone and benzo(b)fluorenone were explored in an attempt to understand the solvatochromic response of tryptanthrin. Such attempts include models dependent on non-radiative decay pathways like intersystem crossing, internal conversion, and hydrogen bonding interactions.
Resumo:
The Third Section was an instrument not so much of oppression as of information, propaganda and education. Under Nicholas I, the press did not represent public opinion, but rather the official point of view. It was intended to shape public opinion rather than to express it and much of the Third Section's activity focused on creating the best possible contacts with journalists and men of letters. The Third Section supervised literary activities by examining works in print and collecting information through its agents. It rewarded those authors whose work was approved by the emperor, it used writers to pursue its goals, especially in order to "direct minds", but acted as a mediator between the tsar, censors and writers, or sometimes as arbiter in conflicts between writers themselves, and it also acted as a censor. Writers, for their part, served in the Third Section, becoming its agents or consultants, delivering reports to it and writing texts commissioned by the Section. The majority of writers did not see any problems with serving or assisting the Third Section. Ideologies offering an alternative to state monarchism /in professional literature or individual liberalism/ were very weak. The only exception was a small group, mostly composed of eminent and highly educated aristocrats who possessed alternative moral and financial resources. Reitblat showed that the strong ties maintained by some journalists and writers with the Third Section were not unfortunate exceptions due to the low moral qualities of those individuals, but rather a natural phenomenon which reflected the specific nature of the Russian literary system and, more generally, of Russian society as a whole.