A Comparison of Semi-Analytic and Smoothed Particle Hydrodynamics Galaxy Formation

We compare the statistical properties of galaxies found in two different models of hierarchical galaxy formation: the semi-analytic model of Cole et al. and the smoothed particle hydrodynamics (SPH) simulations of Pearce et al. Using a `stripped-down' version of the semi-analytic model which mimics the resolution of the SPH simulations and excludes physical processes not included in them, we find that the two models produce an ensemble of galaxies with remarkably similar properties, although there are some differences in the gas cooling rates and in the number of galaxies that populate halos of different mass. The full semi-analytic model, which has effectively no resolution limit and includes a treatment of star formation and supernovae feedback, produces somewhat different (but readily understandable) results. Agreement is particularly good for the present-day global fractions of hot gas, cold dense (i.e. galactic) gas and uncollapsed gas, for which the SPH and stripped-down semi-analytic calculations differ by at most 25%. In the most massive halos, the stripped-down semi-analytic model predicts, on the whole, up to 50% less gas in galaxies than is seen in the SPH simulations. The two techniques apportion this cold gas somewhat differently amongst galaxies in a given halo. This difference can be tracked down to the greater cooling rate in massive halos in the SPH simulation compared to the semi-analytic model. (abridged)Comment: 19 pages, 13 figures, to appear in MNRAS. Significantly extended to explore galaxy progenitor distributions and behaviour of models at high redshift

Development of techniques for producing static strata maps and development of photointerpretation methods based on multitemporal LANDSAT data

The progress of research conducted in support of the Large Area Crop Inventory Experiment (LACIE) is documented. Specific tasks include (1) evaluation of the static stratification procedure and modification of that procedure if warranted, and (2) the development of alternative photointerpretative techniques to the present LACIE procedures for the identification and selection of training fields (areas)

Development of techniques for producing static strata maps and development of photointerpretive methods based on multitemporal LANDSAT data

Progress in the evaluation of the static stratification procedure and the development of alternative photointerpretive techniques to the present LACIE procedure for the identification of training fields is reported. Statistically significant signature controlling variables were defined for use in refining the stratification procedure. A subset of the 1973-74 Kansas LACIE segments for wheat was analyzed

Arkansas Cotton Variety Test 1999

The primary aim of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties in the major cotton growing areas in Arkansas. This information helps seed dealers establish marketing strategies and assists producers in choosing varieties to plant. In this way the annual test facilitates the inclusion of new, improved genetic material into Arkansas cotton production. The 1999 test had 67 entries (including 25 transgenic genotypes and 35 first-year entries), which were evaluated at sixsites in eastern Arkansas. The presence of four transgenic and five first-year entries among the top 10 yielding entries suggests that improvement is being accomplished in varietal development. This report also includes the Mississippi County Variety Test (an on-farm evaluation of selected varieties) and on-farm variety trials conducted by the Cooperative Extension Service

Application of remote sensing to selected problems within the state of California

Specific case studies undertaken to demonstrate the usefulness of remote sensing technology to resource managers in California are highlighted. Applications discussed include the mapping and quantization of wildland fire fuels in Mendocino and Shasta Counties as well as in the Central Valley; the development of a digital spectral/terrain data set for Colusa County; the Forsythe Planning Experiment to maximize the usefulness of inputs from LANDSAT and geographic information systems to county planning in Mendocino County; the development of a digital data bank for Big Basin State Park in Santa Cruz County; the detection of salinity related cotton canopy reflectance differences in the Central Valley; and the surveying of avocado acreage and that of other fruits and nut crops in Southern California. Special studies include the interpretability of high altitude, large format photography of forested areas for coordinated resource planning using U-2 photographs of the NASA Bucks Lake Forestry test site in the Plumas National Forest in the Sierra Nevada Mountains

Application of remote sensing to selected problems within the state of California

There are no author-identified significant results in this report

Optical image of a cometary nucleus: 1980 flyby of Comet Encke

The feasibility was investigated of obtaining optical images of a cometary nucleus via a flyby of Comet Encke. A physical model of the dust cloud surrounding the nucleus was developed by using available physical data and theoretical knowledge of cometary physics. Using this model and a Mie scattering code, calculations were made of the absolute surface brightness of the dust in the line of sight of the on-board camera and the relative surface brightness of the dust compared to the nucleus. The brightness was calculated as a function of heliocentric distance and for different phase angles (sun-comet-spacecraft angle)

Kilohertz QPOs in Neutron Star Binaries modeled as Keplerian Oscillations in a Rotating Frame of Reference

Since the discovery of kHz quasi-periodic oscillations (QPO) in neutron star binaries, the difference between peak frequencies of two modes in the upper part of the spectrum, i.e. Delta (omega)=omega_h-omega_K has been studied extensively. The idea that the difference Delta(omega) is constant and (as a beat frequency) is related to the rotational frequency of the neutron star has been tested previously. The observed decrease of Delta(omega) when omega_h and omega_k increase has weakened the beat frequency interpretation. We put forward a different paradigm: a Keplerian oscillator under the influence of the Coriolis force. For such an oscillator, omega_h and the assumed Keplerian frequency omega_k hold an upper hybrid frequency relation: omega^2_h-omega^2_K=4*Omega^2, where Omega is the rotational frequency of the star's magnetosphere near the equatorial plane. For three sources (Sco X-1, 4U 1608-52 and 4U 1702-429), we demonstrate that the solid body rotation Omega=Omega_0=const. is a good first order approximation. Within the second order approximation, the slow variation of Omega as a function of omega_K reveals the structure of the magnetospheric differential rotation. For Sco X-1, the QPO have frequencies approximately 45 and 90 Hz which we interpret as the 1st and 2nd harmonics of the lower branch of the Keplerian oscillations for the rotator with vector Omega not aligned with the normal of the disk: omega_L/2 pi=(Omega/pi)(omega_K/omega_h)sin(delta) where delta is the angle between vector Omega and the vector normal to the disk.Comment: 13 pages, 3 figures, accepted for publications in ApJ Letter

PREDICTIVE TIME MODEL OF AN ANGLIA AUTOFLOW MECHANICAL CHICKEN CATCHING SYSTEM

In this project, a predictive time model was developed for an Anglia Autoflow mechanical chicken catching system. At the completion of poultry growout, hand labor is currently used to collect the birds from the house, although some integrators are beginning to incorporate mechanical catching equipment. Several regression models were investigated with the objective of predicting the time taken to catch the chicken. A regression model relating distance to total time (sum of packing time, catching time, movement to catching and movement to packing) provided the best performance. The model was based on data collected from poultry farms on the Delmarva Peninsula during a six-month period. Statistical Analysis System (SAS) and NeuroShell Easy Predictor were used to build the regression and neural network models respectively. Model adequacy was established by both visual inspection and statistical techniques. The models were validated with experimental results not incorporated into the initial model.Livestock Production/Industries,

On hemispheric differences in evoked potentials to speech stimuli

Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks