Discovery of five irregular moons of Neptune

Each giant planet of the Solar System has two main types of moons. 'Regular' moons are typically larger satellites with prograde, nearly circular orbits in the equatorial plane of their host planets at distances of several to tens of planetary radii. The 'irregular' satellites (which are typically smaller) have larger orbits with significant eccentricities and inclinations. Despite these common features, Neptune's irregular satellite system, hitherto thought to consist of Triton and Nereid, has appeared unusual. Triton is as large as Pluto and is postulated to have been captured from heliocentric orbit; it traces a circular but retrograde orbit at 14 planetary radii from Neptune. Nereid, which exhibits one of the largest satellite eccentricities, is believed to have been scattered from a regular satellite orbit to its present orbit during Triton's capture. Here we report the discovery of five irregular moons of Neptune, two with prograde and three with retrograde orbits. These exceedingly faint (apparent red magnitude m(R) = 24.2-25.4) moons, with diameters of 30 to 50 km, were presumably captured by Neptune.     

Prostaglandin E1 induced salivary secretion

Summary PGE₁ but not PGF₂ at 500–1000 g/kg induced a slow and sparse flow from the parotid and no flow at all from submaxillary glands. Composition of PGE₁-induced parotid saliva was quite different from that evoked by any autonomic agonists. The present study suggests that PGE₁ might act directly on parotid acinar cells.Acknowledgment. This work was supported by NIDR grant DE05633. The authors wish to thank Ms Sonya Wynn for her technical assistance.     

用模糊综合评判法评价变电所所址

变电所选址是电力系统规划的一个重要环节。但与变电所所址有关的因素错综复杂,很难仅凭经验就能确定最佳所址。本文采用模糊综合评判方法对备选所址进行评判,确定其优先次序。在模糊综合评判中,各因素的权重分配对结果起决定性作用,用层次分析法确定与所址密切相关的各个因素相对总体目标而言的权重,使得权重的确定更科学。算例表明该方法是可行的。     

Imaging of Titan from the Cassini spacecraft

Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150-200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.     

Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil

During the last glacial period, large millennial-scale temperature oscillations--the 'Dansgaard/Oeschger' cycles--were the primary climate signal in Northern Hemisphere climate archives from the high latitudes to the tropics. But whether the influence of these abrupt climate changes extended to the tropical and subtropical Southern Hemisphere, where changes in insolation are thought to be the main direct forcing of climate, has remained unclear. Here we present a high-resolution oxygen isotope record of a U/Th-dated stalagmite from subtropical southern Brazil, covering the past 116,200 years. The oxygen isotope signature varies with shifts in the source region and amount of rainfall in the area, and hence records changes in atmospheric circulation and convective intensity over South America. We find that these variations in rainfall source and amount are primarily driven by summer solar radiation, which is controlled by the Earth's precessional cycle. The Dansgaard/Oeschger cycles can be detected in our record and therefore we confirm that they also affect the tropical hydrological cycle, but that in southern subtropical Brazil, millennial-scale climate changes are not as dominant as they are in the Northern Hemisphere.     

Retinal blur and midbrain cell response

Summary The responses of certain photically responsive cells of the superior colliculus were found acutely dependent on the focal condition of the retinal image.This work was supported by U.S.P.H.S. Grant No. EY01325.     

Daily variations in pigeon cropsac responses to prolactin

Zusammenfassung Es wird festgestellt, dass die Ansprechbarkeit des Taubenkropfsackes auf Prolactin in Abhängigkeit vom hormonalen Zustand des Versuchstieres von Tag zu Tag verschieden ist.

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Our study was supported by a Public Health Service Research Grant No. 5 R01 AM13400 and a Public Health Service Research Career Development Award No. GM-17, 898, toAlbert H. Meier. The ovine prolactin was a gift of the Endocrinology Study Section of the National Institutes of Health. We thank Dr.P. E. Schilling of the Computer Center at Louisiana State University for making the statistical evaluations.     

An ultrastructural investigation of the effects of perinatal malnutrition on E-PTA-stained synaptic junctions.

The effect of protein-deficient diet on E-PTA stained synapses in rat cerebral cortex was studied by electron microscopy. No significant difference was observed in synaptic morphology between control and malnourished animals at 35 days postnatal.