Protostellar Disk Evolution Over Million-Year Timescales with a Prescription for Magnetized Turbulence

Magnetorotational instability (MRI) is the most promising mechanism behind accretion in low-mass protostellar disks. Here we present the first analysis of the global structure and evolution of non-ideal MRI-driven T-Tauri disks on million-year timescales. We accomplish this in a 1+1D simulation by calculating magnetic diffusivities and utilizing turbulence activity criteria to determine thermal structure and accretion rate without resorting to a 3-D magnetohydrodynamical (MHD) simulation. Our major findings are as follows. First, even for modest surface densities of just a few times the minimum-mass solar nebula, the dead zone encompasses the giant planet-forming region, preserving any compositional gradients. Second, the surface density of the active layer is nearly constant in time at roughly 10 g/cm2, which we use to derive a simple prescription for viscous heating in MRI-active disks for those who wish to avoid detailed MHD computations. Furthermore, unlike a standard disk with constant-alpha viscosity, the disk midplane does not cool off over time, though the surface cools as the star evolves along the Hayashi track. The ice line is firmly in the terrestrial planet-forming region throughout disk evolution and can move either inward or outward with time, depending on whether pileups form near the star. Finally, steady-state mass transport is a poor description of flow through an MRI-active disk. We caution that MRI activity is sensitive to many parameters, including stellar X-ray flux, grain size, gas/small grain mass ratio and magnetic field strength, and we have not performed an exhaustive parameter study here.Comment: Accepted for publication in Astrophysical Journal. 19 pages, including 8 figure

QUANTIFYING THE GRADIENTS EXPOSED TO A PROFESSIONAL GOLFER DURING A ROUND OF GOLF

Research has suggested that that when performing a tee shot a gradient slope of 4.4% (2.25°) and above it is noticeable to the golfer and may cause an adjustment to their normal stance (Linde, 2005). To quantify what gradients were exposed to a golfer during a round of golf an inclinometer was utilised to measure the gradient of shots in open play from around 16 golf courses across the UK. Twenty two right handed male professional golfers were recruited and the inclinometer was placed between the inside of the feet and the ball. The results showed that over 50% of shots where performed on an incline greater than 2.25° mainly ranging from 0 to (+/-) 10°. These results suggest that future research is required to investigate the effects of gradient on the mechanics of the golf swing

The Relationships between School Personnel Attitudes about At Risk Students, the At Riskness of the Student Population, and Effort Expended for At Risk Students

This study was conducted to address: (1) the identification of at risk students; (2) the provision of help appropriate to their needs; and (3) discovery of ways to increase those students\u27 probability of succeeding in school and in life. The study analyzed data generated through the Phi Delta Kappa Study of Students at Risk that involved 22,018 students enrolled in 276 elementary, middle and high schools nationwide. Surveys were gathered from 276 principals and 9,652 teachers. A literature review examines general efforts including ability grouping, promotion/retention, reduction in class size, and pull-out programs, as well as specific elementary, secondary, and successful individual programs. Data were collected through survey and interview techniques, and variables (school description, and school personnel attitudes) were compared. Results show that the perceptions of educators dealing with at risk students varied, and the variation was not necessarily associated with the particular school situation in which they worked. Preferred strategies such as removing at risk students to another class are no longer supported as effective tools for increasing the achievement. Thirteen appendices consisting mainly of statistical results of the study

THE EFFECTS OF COMPRESSION SHORTS ON MUSCLE OSCILLATION AND LONG JUMP PERFROMANCE

Compression garments were used to explore their effect on athletic performance and muscle oscillation during a 3-step long jump task. The study consisted of a 3 dimensional kinematic analysis (Vicon Motus 9.2) with force data collected by a Kistler force platform. Ten male subjects performed 6 jumps under 2 conditions, bare leg (control condition) and with the compression shorts. Two-tailed paired samples T-test were conducted to discover significant changes in the measures of Muscle Oscillation (MO), Peak Vertical Ground Reaction Force (PVGRF), Peak Horizontal Ground Reaction Force (PHGRF) and Jump Length. The findings of the study suggest that long jump performance can be increased (.18m) while wearing compression shorts, although the legs ability to disperse force may be reduced by the garment

Deep GALEX Observations of the Coma Cluster: Source Catalog and Galaxy Counts

We present a source catalog from deep 26 ks GALEX observations of the Coma cluster in the far-UV (FUV; 1530 A) and near-UV (NUV; 2310 A) wavebands. The observed field is centered 0.9 deg (1.6 Mpc) south-west of the Coma core, and has full optical photometric coverage with SDSS. The catalog consists of 9700 galaxies with GALEX and SDSS photometry, including 242 spectroscopically-confirmed Coma member galaxies that range from giant spirals and elliptical galaxies to dwarf irregular and early-type galaxies. The full multi-wavelength catalog (cluster plus background galaxies) is ~80% complete to NUV=23 and FUV=23.5, and has a limiting depth at NUV=24.5 and FUV=25.0 which corresponds to a star formation rate of ~0.001 Msun/yr at the distance of Coma. Our deep GALEX observations required a two-fold approach to generating a source catalog: we used a Bayesian deblending algorithm to measure faint and compact sources (using SDSS coordinates as a position prior), and relied on the GALEX pipeline catalog for bright/extended objects. We performed simulations to assess the influence that systematic effects (e.g. object blends, source confusion, Eddington Bias) have on source detection and photometry when using both methods. The Bayesian deblending method roughly doubles the number of source detections and provides reliable photometry to a few magnitudes deeper than the GALEX pipeline catalog. This method is also free from source confusion over the UV magnitude range studied here; conversely, we estimate that the GALEX pipeline catalogs are confusion limited at magnitudes fainter than NUV~23 and FUV~24. We have measured the total UV galaxy counts using our catalog and report a ~50% excess of counts across FUV=22-23.5 and NUV=21.5-23 relative to previous GALEX measurements, which is not attributed to cluster member galaxies. Our galaxy counts are a better match to deeper UV counts measured with HST.Comment: 27 pages, 13 figures, 4 tables, accepted for publication in ApJ

A reduced set of moves on one-vertex ribbon graphs coming from links

Every link in R^3 can be represented by a one-vertex ribbon graph. We prove a Markov type theorem on this subset of link diagrams.Comment: 14 pages, 15 figure

Demonstrating Calcium Oxide Treatment of Forages

Corn stalks treated with calcium oxide CaO showed no change in in vitro dry matter digestibility (IVDMD) at 3 or 7 days after treatment, but a small increase of 2 units in IVDMD at 14 days after treatment. Corn stalks and corn silage mixed had no change 3 days after treatment but a 7unit IVDMD increase by day 7 and a 1 unit increase at day 14. Corn silage alone had no change at day 3 or 7 but at day 14 there was a small 2 unit increase in IVDMD. Cornstalks ground to a smaller particle size and treated with calcium oxide stalks increased 5 units on average in IVDMD. There was considerable variation in the treated samples IVDMD

Fish Assemblages and Benthic Biota Associated with Natural Hard-Bottom Areas in the Northwestern Gulf of Mexico

We report new observations of fish and benthic invertebrate assemblages at shallow-water (\u3c35 m depth), hard-bottom sites in the northwestern Gulf of Mexico. The biota of these previously unstudied areas and of three high-relief features in deeper water was observed during May 1980 using a combination of diver reconnaissance, videotape surveys, still-camera photography, and collection of invertebrates for identification. The six hard-bottom sites in shallow water typically comprised, small, often patchy, rock outcrops, and the associated sessile invertebrates included hydroids, bryozoans, sponges, octocorals, and ahermatypic stony corals. Sea urchins and arrow crabs were the most common motile epifauna. Fish assemblages were typified by red snapper, Atlantic spadefish, blue runner gray triggerfish, sheepshead, and tomtate. Three deeper stations had many of the same fish and invertebrate species, but also possessed a more tropical assemblage including fire corals, antipatharians, spiny lobsters, and a variety of tropical fish species. Hermatypic corals characteristic of some large, offshore banks were not abundant at any of the sites. Differences in the composition of fish assemblages between nearshore and deeper stations parallel those previously observed at petroleum platforms in the area. Shallow-water stations presumably experience a greater seasonal temperature range and lower absolute temperatures in winter and may be exposed to stresses such a lowered salinity and depleted oxygen levels due to their relative proximity to Mississippi River discharge. The fauna of these shallow hard-bottom sites has predominantly warm-temperate rather than tropical affinities