Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation

Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100-1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H(2)SO(4)-H(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.     

On some interesting features of the hypothalamo-hypophysial vascularization in the lizardHemidactylus flaviviridis

Zusammenfassung Tuscheinjektion lässt Verbindungen der Kapillarnetze in Medinalobus mit denen des Neurallobus der Hypophyse bei einer Eidechse erkennen. Der Intermediärteil ist ganz ohne Gefässe, was im Hinblick auf einen möglichen Hormonfluss von Interesse ist.

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The authors are indebted to Dr.K. N. Udupa, Director, Institute of Medical Sciences and Dr.L. M. Singh, Officer in charge of the laboratory for providing facilities and encouragement. One of us (S.H.) is grateful to the Indian Council of Medical Research for the award of a postdoctoral fellowship, during the tenure of which this work was carried out.     

On the radio-sensitivity of rat liver

Résumé Les lobes antérieurs du foie de rats ont été prélevés et exposés aux rayons-X jusqu'à des doses de 91 kR et en employant comme indicateur biochimique de survivance l'incorporation de³H-leucine. Une dose de 45 kR fit diminuer l'incorporation au cours des 3 premiers jours suivant l'exposition; ce type de blessure de radiation nécessite donc plusieurs jours pour se manifester. Ces rêsultats montrent qu'au commencement de l'interphase l'hépatocyte est extrêmement résistant à la mort par radiation.     

ALKALINE PULP OF CORN STALKS

Pulping of corn stalks was studied in soda,soda-anthraquinone (AQ), kraft and kraft-AQ processes. The time, temperature and alkali concentration were varied in soda process. In respect to kappa number and pulp yield, 1 hour cooking at 1400C in 14% alkali were best conditions for corn stalks pulping. Pulp yield was increased by 5.5% and kappa number was reduced by 4.4 points with an addition of 0.05% AQ in the soda liquor. Breaking length was better in soda-AQ process than soda process but tear strength was inferior. In the kraft process, pulp yield was increased with increasing sulphidity and decreasing active alkali. The effectiveness of AQ in the low and high sulphidity kraft process was studied. Results showed that AQ was more effective in low sulphidity than high sulphidity. Strength properties in kraft processes were better than the soda and soda-AQ processes.     

Dogs cloned from adult somatic cells

Several mammals--including sheep, mice, cows, goats, pigs, rabbits, cats, a mule, a horse and a litter of three rats--have been cloned by transfer of a nucleus from a somatic cell into an egg cell (oocyte) that has had its nucleus removed. This technology has not so far been successful in dogs because of the difficulty of maturing canine oocytes in vitro. Here we describe the cloning of two Afghan hounds by nuclear transfer from adult skin cells into oocytes that had matured in vivo. Together with detailed sequence information generated by the canine-genome project, the ability to clone dogs by somatic-cell nuclear transfer should help to determine genetic and environmental contributions to the diverse biological and behavioural traits associated with the many different canine breeds.     

Identification of the gene that, when mutated, causes the human obesity syndrome BBS4

Bardet-Biedl syndrome (BBS, MIM 209900) is a heterogeneous autosomal recessive disorder characterized by obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation, and hypogenitalism. The disorder is also associated with diabetes mellitus, hypertension, and congenital heart disease. Six distinct BBS loci map to 11q13 (BBS1), 16q21 (BBS2), 3p13-p12 (BBS3), 15q22.3-q23 (BBS4), 2q31 (BBS5), and 20p12 (BBS6). Although BBS is rare in the general population (<1/100,000), there is considerable interest in identifying the genes causing BBS because components of the phenotype, such as obesity and diabetes, are common. We and others have demonstrated that BBS6 is caused by mutations in the gene MKKS (refs. 12,13), mutation of which also causes McKusick-Kaufman syndrome (hydrometrocolpos, post-axial polydactyly, and congenital heart defects). MKKS has sequence homology to the alpha subunit of a prokaryotic chaperonin in the thermosome Thermoplasma acidophilum. We recently identified a novel gene that causes BBS2. The BBS2 protein has no significant similarity to other chaperonins or known proteins. Here we report the positional cloning and identification of mutations in BBS patients in a novel gene designated BBS4.