Three-Body Capture of Irregular Satellites: Application to Jupiter

We investigate a new theory of the origin of the irregular satellites of the giant planets: capture of one member of a ~100-km binary asteroid after tidal disruption. The energy loss from disruption is sufficient for capture, but it cannot deliver the bodies directly to the observed orbits of the irregular satellites. Instead, the long-lived capture orbits subsequently evolve inward due to interactions with a tenuous circumplanetary gas disk. We focus on the capture by Jupiter, which, due to its large mass, provides the most stringent test of our model. We investigate the possible fates of disrupted bodies, the differences between prograde and retrograde captures, and the effects of Callisto on captured objects. We make an impulse approximation and discuss how it allows us to generalize capture results from equal-mass binaries to binaries with arbitrary mass ratios. We find that at Jupiter, binaries offer an increase of a factor of ~10 in the capture rate of 100-km objects as compared to single bodies, for objects separated by tens of radii that approach the planet on relatively low-energy trajectories. These bodies are at risk of collision with Callisto, but may be preserved by gas drag if their pericenters are raised quickly enough. We conclude that our mechanism is as capable of producing large irregular satellites as previous suggestions, and it avoids several problems faced by alternative models.Comment: 39 pages, 12 figures, 1 table, submitted to Icaru

Silacycles: novel reagents in asymmetric synthesis

Silicon based organic reagents have enjoyed a wealth of applications in the last thirty year. However, the development of organosilanes for asymmetric synthesis has been less prolific. The drawbacks of using 'Si-centred' chiral organosilanes has led to 'C- centred' organosilicon compounds being the substrate of choice. This research has been directed at the synthesis and application of C(_2) symmetric 'C-centred' cyclic organosilicon species and their potential applications in asymmetric synthesis. A variety of synthetic methods have been considered, the most successful of which has been the double asymmetric hydroboration of substituted divinylsilanes. This has allowed the use of unusual boron redistribution chemistry to give access to both acyclic and cyclic rmw-substituted organosilicon compounds with high stereoselectivity. A new method for the synthesis of dichlorosilanes from their diphenyl analogue has been developed and has been shown to occur almost instantaneously and in good yield. Finally, the application of dichlorosilacycles in tethered Diels-Alder reactions has been investigated and has been shown to give enhanced rates of reaction when compared to acyclic silicon tethers

Effects of dietary fat and protein on tissue cholesterol

One hundred four adult male rats, which had been fed a commercial rat diet from weaning, were randomly allotted to four dietary groups, 26 rats per group. Two randomly selected rats from each group were sacrificed at the following days on experiment: 0, 7, 9, 11, 13, 15, 18, 22, 30, 36, 42, and 48. The eight remaining rats (which were fed the diets to provide replacements in case of animal loss) were not used. The objective of the experiment was to determine the effects of sources of dietary fat and protein on tissue cholesterol levels and on cholestero-genesis in the liver and small intestine. Experimental diets were isocaloric and provided 38 and 19% of the calories from fat and protein, respectively. The principal fat and protein sources for the four respective diets were (1) soybean oil and soy protein isolate, (2) soybean oil and casein, (3) beef tallow and soy protein isolate, and (4) beef tallow and casein. The commercial rat diet contained no cholesterol whereas all four experimental diets were standardized to 0.2% cholesterol;Blood plasma cholesterol levels of rats fed soybean oil (polyunsaturated fat) were 10% lower than those of rats fed tallow (saturated fat). Furthermore, plasma cholesterol levels of rats fed soy protein (plant protein) were 13% lower than those of rats fed casein (animal protein). The eight rats sacrificed at the beginning of the experiment (0 days) had, on the average, lower plasma cholesterol levels than rats fed any of the experimental diets;Liver cholesterol levels were higher for rats fed soybean oil or casein protein than for those fed tallow or soy protein isolate. Cholesterol content of the intestinal wall, however, was not significantly affected by diet. Furthermore, dietary fat and protein source had no significant effect on hepatic cholesterogenesis; however, intestinal cholesterogenesis was higher in animals fed beef tallow and casein. The tallow plus casein diet demonstrated a synergistic response in the small intestinal cholesterol synthetic rates. Intestinal cholesterogenesis of the eight rats sacrificed at 0 days was greater, on the average, than of rats fed any of the experimental diets;These results suggest that the hypocholesterolemic action of unsaturated fat and soy protein may be related to a lowered intestinal cholesterogenesis. In addition, dietary polyunsaturated fat (soybean oil) caused a redistribution of cholesterol from plasma to liver

Early Contractional History of the Funeral Mountains and its Influence on the Formation of the Funeral Mountains Metamorphic Core Complex, Death Valley, CA

Zones of localized crustal thickening in orogenic belts commonly host low-angle normal faults, which have been controversial since their recognition. The metamorphic core complexes of the Sevier hinterland are localized within a belt that is attributed with the highest degrees of crustal thickening during Sevier orogenesis. This association of deep-rooted detachment faulting and early contractional deformation indicates an important link between the two processes, however repeated tectonic episodes often overprint and obscure the earlier fabrics, making this link difficult to study. The Funeral Mountains metamorphic core complex, located in Death Valley, CA, has a complex history of protracted SE-contraction and tectonic burial of Late Jurassic age that has since been overprinting by two periods of NW-directed detachment faulting during Late Cretaceous and Miocene time. Exposure of a Barrovian-style metamorphic field gradient and a thick stratigraphic section with large rheologic contrasts has provided a unique opportunity to investigate the apparent genetic link between contractional structures and the development of low-angle normal faults. Detailed mapping at 1:10000 scale has revealed evidence of four separate fabric forming events. Evidence for early burial was found within the Kingston Peak diamictite, which contains a well-developed bedding-parallel foliation with asymmetric strained clasts with SE-vergence. This early foliation was subsequently folded during a second period of contraction of Early Cretaceous(?) age. This event produced NNE-SSW mesoscopic to map-scale folds with SE-vergence. A new U-Pb zircon age of 95.63 ± 0.95 Ma, from a peraluminous granite intrusion that preserves no contractional fabrics, may provide lower constraints on the age of contraction. Two periods of top-NW shear overprint the earlier top-SE fabrics during the Late Cretaceous and Miocene, which produced two intracore shear zones, the Monarch Canyon shear zone and the Eastern shear zone, and the primary dome forming fault, the Boundary Canyon Detachment fault. The contractional fabrics are subparallel with extensional structures of opposite kinematics, indicating deformation generated by structures of similar orientations. These observations, in conjunction with the absence of an enigmatic thrust fault responsible for the deep burial of the Funeral Mountains, has led us to hypothesize that tectonic reactivation of a Late Jurassic thrust fault was the primary mechanism behind detachment faulting within this complex

Perfectionism in Social Anxiety: Cognitive and Behavioral Correlates

The purpose of this study was to examine the relationship between perfectionism and social anxiety in general as well as social phobia, specifically. Subjects completed the Personal Standards Scale, the Fear of Negative Evaluation scale, and the Social Phobia and Agoraphobia Inventory. Results indicated that neurotic perfectionism is positively associated with both general social anxiety and social phobia. Moreover, the neurotic elements of perfectionism -- concern over making mistakes and doubts about actions -- appeared to be better predictors of social anxiety than high performance standards alone. Differences between social phobia and social anxiety secondary to agoraphobia as related to perfectionism were addressed, and directions for future research are discussed

A Comparison of the Temporal Spawning Distributions and Growth Rates of Young-of-the-year Redear Sunfish (Lepomis microlophus) and Bluegill (Lepomis macrochirus) in Three Illinois Impoundments

The purpose of this study was to compare the temporal spawning distribution and growth rates of bluegill (Lepomis macrochirus) and redear sunfish (Lepomis microlophus) in Illinois impoundments. Otolith sagittae were used to age the fish and to determine the intervals of successful spawning for both species. Readear sunfish initiated spawning slightly before or a the same time as bluegill; however, bluegill spawned for twice as long as redear sunfish in all study impoundments. The earliest spawned fish of both species showed the fastest growth and the earliest spawned redear sunfish grew faster than did the earliest spawned bluegill. Growth rates of both species declined constantly, decreasing for each day later in the summer that they were spawned. The length to age regressions were positively correlated showing that the growth rates of the fish declined constantly throughout the growing season. There was a direct relationship between otolith radius and fish length for both species, but the relationship seemed to be population specific and differed among impoundments sampled

The Journey to Worship: A Case Study in Waterloo, Ontario

This paper examines religious spatial interaction within an urban environment and as such contributes to the sparse literature on the Geography of Religion. It is the specific purpose to illustrate the journey to worship of households in the City of Waterloo, Ontario and to explain the spatial pattern utilizing the Principle of Least Effort. It is discovered that if historical tension and dimensional tension are considered, one is able to predict the actual pattern of the journey to worship with seventy per cent accuracy. The fact that a large per cent of the sample attend the closest church of their particular denomination at the time of entry into the earliest address in the Twin Cities appears to indicate that the distance to church is an important attraction factor. The travel patterns of all denominations are influenced similarly by the principle of least effort. This effect of the principle of least effort can be described mathematically using the Pareto function. An analysis of the socio-economic factors that could effect the space preference of households indicates that income, age, trip frequency, the number of programs utilized and family size do not significantly explain the travel patterns of the journey to worship to any great degree. In a final chapter the perception of households is analyzed as to which factors are considered most important in attracting the household to church. It is discovered that a large percentage of the households indicated that proximity to church is the most important attraction factor. This subjective aspect verifies the objective conclusions on the important effect of the least effort principle on the journey to worship of Waterloo households. Those individuals who are responsible for church location and planning may well find this paper useful in their task