Quasars: Millisecond-of-Arc Structure Revealed by Very-Long-Baseline Interferometry

Observations with the Goldstone-Haystack radio interferometer of the quasars 3C 279 and 3C 273 have disclosed the presence of fine structure in their radio emissions. Although the interpretation is not unique, the fringe-amplitude data for quasar 3C 279 are quite consistent with emissions from two points, each contributing equally to the correlated flux. The separation of the two points is estimated to be (1.55 +/- 0.05) x 10(-3) arc second, or about 20 light years at the distance of 3 x 10(9) light years inferred from optical red-shift data. The formal uncertainty in the right-ascension component of the separation is about 6 x 10(-6) arc second; differential proper motion in this direction at half the speed of light could be discerned within a year. The fringe-amplitude data of quasar 3C 273 allow similar, but less definitive, interpretations.     

Hazard,risk and agrarian adaptations in a hyperarid watershed: El Niño floods,streambank erosion,and the cultural bounds of vulnerability in the Andean Middle Horizon

Peru's Osmore drainage, also known as the Moquegua Valley, is one of the driest regions on Earth, yet agricultural development has supported complex societies in the basin for almost 4000 yrs because of canal construction and irrigation. We compare the distinct agrarian and settlement systems of three coeval archaeological cultures in this arid region, Huaracane, Wari and Tiwanaku, and how each adapted—or failed to adapt—to geomorphic and climatic hazards. Systematic settlement pattern survey and radiocarbon dating along with geomorphological analysis of flood history and riverine processes permit detailed discussion of agrarian strategies during the Formative (1800 BC–AD 500) and Middle Horizon (AD 500–1000) periods, with distinct settlement “niches” in terms of agricultural practices and longitudinal position in the drainage, and lateral location relative to the floodplain. These adaptive strategies each manifest distinct “bounds of adaptability” to natural hazard, climate events and social stressors, and thus varying risk profiles. Besides the continual risk associated with sustained droughts, the Atacama and Peruvian Coastal Desert and culturally connected highland Altiplano are also vulnerable to the vagaries of the El Niño-Southern Oscillation (ENSO) leading to catastrophic floods in the mid-valley during warm phase ENSOs, in tandem with simultaneous hazards in other regions inhabited by these transregional cultures. By comparing the archaeological record of Wari, Huaracane, and Tiwanaku culture settlements with geomorphic signatures of catastrophic El Niños, we show that the viability of each cultural sequence depended on specific relationships to floodplain streambank erosion, construction and reworking over multiple time scales.     

The sulfur cycle

Even granting our uncertainties about parts of our model of the sulfur cycle, we can draw some conclusions from it: 1) Man is now contributing about one half as much as nature to the total atmospheric burden of sulfur compounds, but by A.D. 2000 he will be contributing about as much, and in the Northern Hemisphere alone he will be more than matching nature. 2) In industrialized regions he is overwhelming natural processes, and the removal processes are slow enough (several days, at least) so that the increased concentration is marked for hundreds to thousands of kilometers downwind. 3) Our main areas of uncertainty, and ones that demand immediate attention because of their importance to the regional air pollution question, are: (i) the rates of conversion of H(2)S and SO(2) to sulfate particles in polluted as well as unpolluted atmospheres; (ii) the efficiency of removal of sulfur compounds by precipitation in polluted air. And for a better understanding of the global model we need to know: (i) the amount of biogenic H(2)S that enters the atmosphere over the continents and coastal areas; (ii) means of distinguishing man-made and biogenic contributions to excess sulfate in air and precipitation; (iii) the volcanic production of sulfur compounds, and their influence on the particle concentration in the stratosphere; (iv) the large-scale atmospheric circulation patterns that exchange air between stratosphere and troposphere (although absolute amounts of sulfate particles involved are small relative to the lower tropospheric burden); (v) the role of the oceans as sources or sinks for SO(2).     

Tyramine-H3: deaminated metabolites in neuroblastoma tumors and in continuous cell line of a neuroblastoma

Neuroblastoma tumors, as well as cultured cells of neuroblastoma, contain high monoamine oxidase activity. The major deaminated metabolite of tyramine-H(3) in the incubation mixtures with the tumors or with the cultured cells is p-hydroxyphenylacetaldehyde. Upon addition of reduced nicotinamide-adenine dinucleotide phosphate, the aldehyde was further metabolized by the reductive pathway to p-hydroxyphenylethanol, whereas upon addition of nicotinamide-adenine dinucleotide phosphate the aldehyde was only metabolized to a minor extent by the oxidative pathway to p-hydroxyphenylacetic acid. Aldehyde dehydrogenase activity is very low in the neuroblastoma tumors and in the cultured neuroblastoma cells. The generation of aldehydes and alcohols by the action of monoamine oxidase suggests that the deaminated metabolites of biogenic amines might exhibit some toxic effects in neuroblastoma patients.     

Broad-spectrum antiviral activity of Virazole: 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide

Virazole is a synthetic nucleoside active in tissue culture against at least 16 DNA and RNA viruses. Applied topically, it inhibits herpetic keratitis in rabbits and tail lesions induced by herpes, vaccinia, and vesicular stomatitis viruses in mice. Injected intraperitoneally into mice, it inhibits splenomegaly and hepatomegaly induced by Friend leukemia virus and respiratory infections caused by influenza A(O), A(2), and B viruses and parainfluenza 1 virus. infections is also effective.     

Spinophilin blocks arrestin actions in vitro and in vivo at G protein-coupled receptors

Arrestin regulates almost all G protein-coupled receptor (GPCR)-mediated signaling and trafficking. We report that the multidomain protein, spinophilin, antagonizes these multiple arrestin functions. Through blocking G protein receptor kinase 2 (GRK2) association with receptor-Gbetagamma complexes, spinophilin reduces arrestin-stabilized receptor phosphorylation, receptor endocytosis, and the acceleration of mitogen-activated protein kinase (MAPK) activity following endocytosis. Spinophilin knockout mice were more sensitive than wild-type mice to sedation elicited by stimulation of alpha2 adrenergic receptors, whereas arrestin 3 knockout mice were more resistant, indicating that the signal-promoting, rather than the signal-terminating, roles of arrestin are more important for certain response pathways. The reciprocal interactions of GPCRs with spinophilin and arrestin represent a regulatory mechanism for fine-tuning complex receptor-orchestrated cell signaling and responses.     

External control of 20th century temperature by natural and anthropogenic forcings

A comparison of observations with simulations of a coupled ocean-atmosphere general circulation model shows that both natural and anthropogenic factors have contributed significantly to 20th century temperature changes. The model successfully simulates global mean and large-scale land temperature variations, indicating that the climate response on these scales is strongly influenced by external factors. More than 80% of observed multidecadal-scale global mean temperature variations and more than 60% of 10- to 50-year land temperature variations are due to changes in external forcings. Anthropogenic global warming under a standard emissions scenario is predicted to continue at a rate similar to that observed in recent decades.     

Sarcoplasmic reticulum of striated muscle: localization of potential calcium binding sites

Fish branchial muscle stained at a low pH with thorium dioxide shows localization of the stain over the sacroplasmic reticulum. Binding of the positively charged thorium micelles with dissociated acid groups of polyanions in this region suggests a possible mechanism for the storage and release of divalent cations such as calcium.