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Dynamics, stratospheric ozone, and climate change
Dynamics affects the distribution and abundance of stratospheric ozone directly through transport of ozone itself and indirectly through its effect on ozone chemistry via temperature and transport of other chemical species. Dynamical processes must be considered in order to understand past ozone changes, especially in the northern hemisphere where there appears to be significant low-frequency variability which can look “trend-like” on decadal time scales. A major challenge is to quantify the predictable, or deterministic, component of past ozone changes. Over the coming century, changes in climate will affect the expected recovery of ozone. For policy reasons it is important to be able to distinguish and separately attribute the effects of ozone-depleting substances and greenhouse gases on both ozone and climate. While the radiative-chemical effects can be relatively easily identified, this is not so evident for dynamics — yet dynamical changes (e.g., changes in the Brewer-Dobson circulation) could have a first-order effect on ozone over particular regions. Understanding the predictability and robustness of such dynamical changes represents another major challenge. Chemistry-climate models have recently emerged as useful tools for addressing these questions, as they provide a self-consistent representation of dynamical aspects of climate and their coupling to ozone chemistry. We can expect such models to play an increasingly central role in the study of ozone and climate in the future, analogous to the central role of global climate models in the study of tropospheric climate change
ATAXIA-TELANGIECTASIA (LOUIS-BAR SYNDROME): REPORT OF A CASE
Ataxia-telangiectasia is a rare genetic disorder with multisystem manifestations. Major symptoms include development of ataxia and oculomotor disorders in early childhood. Telangiectasias may appear at the same period of time or later that is more often. They are typically located on the conjunctiva and on the face. In the vast majority of patients, primary cell-humoral immunodeficiency is observed. Repeated and protracted infectious diseases are typical. Patients often develop chronic respiratory disorders. They also have an increased risk of malignancies. Laboratory findings usually include an increase in the level of alpha-fetoprotein and impaired immunological status: a decrease in T- and B- lymphocytes counts, and also a decrease in the levels of IgA, IgG, IgE. MRI of the brain shows signs of atrophy of the cerebellar vermis and hemispheres, which become more pronounced at a later age. The final diagnosis is made on the basis of the results of genetic testing, when mutations of the ATM gene are detected. The typical course of the disease and the steps of the diagnostic process are illustrated by our own clinical observation
Radiative analysis of global mean temperature trends in the middle atmosphere: Effects of non-locality and secondary absorption bands
Reaction of indolizines with elemental sulfur
The fusion of 3,8-diphenyl-, 1,2-diphenyl-, and 6-methyl-2,7-diphenyl-indolizines with sulfur results in the formation of bis(indolizin-3-yl) disulfides with the respective substituents. Bis(2,8-diphenylindolizin-3-yl) disulfide is reduced to the original indolizine, and its treatment with nitric acid gives 2,8-diphenyl-1, 3-dinitroindolizine. Bis(dibenzo[b,g]indolizin-11-yl) disulfide is obtained from dibenzo[b,g]indolizine. The formation of the disulfides is apparently a general region of indolizines without substituents at C3 or C1 of the pyrrole ring. The structures of the disulfides obtained have been confirmed by data from x-ray diffraction analysis and NMR spectroscopy. © 1985 Plenum Publishing Corporation
Reaction of indolizines with elemental sulfur
The fusion of 3,8-diphenyl-, 1,2-diphenyl-, and 6-methyl-2,7-diphenyl-indolizines with sulfur results in the formation of bis(indolizin-3-yl) disulfides with the respective substituents. Bis(2,8-diphenylindolizin-3-yl) disulfide is reduced to the original indolizine, and its treatment with nitric acid gives 2,8-diphenyl-1, 3-dinitroindolizine. Bis(dibenzo[b,g]indolizin-11-yl) disulfide is obtained from dibenzo[b,g]indolizine. The formation of the disulfides is apparently a general region of indolizines without substituents at C3 or C1 of the pyrrole ring. The structures of the disulfides obtained have been confirmed by data from x-ray diffraction analysis and NMR spectroscopy. © 1985 Plenum Publishing Corporation