Research on the properties of circadian systems amenable to study in space

Three areas of inquiry are reported for the Skylab Experiment S-071 whose objective was to study the circadian system of a mammal during space flight. The thermoregulatory behavior of the Perognathus longimembris, or little pocket mouse, was studied under conditions of constant dark and constant temperature in the prolonged weightless environment of Skylab. The following specific questions were studied: (1) the effects of weightlessness on circadian periodicity in the little pocket mouse; (2) stability of the free-running circadian period of body temperature of the little pocket mouse exposed to simulated launch stress; and (3) characteristics of the circadian rhythm of body temperature in the little pocket mouse. Diagrams of the electronic circuitry and hardware used in the experiment are shown and results are given in both graphical and tabular form. The methods used in the experiment are fully documented, along with conclusions and recommendations for future research

Evaluation of factors affecting sale price of performance tested bulls

The objective of this study was to partition the total variability of price received for performance tested bulls into that which is attributed to various selected criteria. The records of twelve Tennessee performance tested bull sales (six junior and six senior) were compiled. These records, collected by the University of Tennessee Extension Service from 1982 through 1987, consisted of 343 junior bulls and 250 senior bulls. An adjusted sale price was calculated using an index which consisted of standardizing feeder cattle prices, slaughter bull prices and an agricultural consumer price index to a 1987-year dollar equivalent, for both data sets. A first analysis was conducted to partition out the effects of the following four discrete variables: (1) year; (2) breed; (3) sire; and (4) preweaning management. By using the beta value estimates of these factors to adjust the data, all records were equalized to a 1987 year, British breed, artificial sire, no-creep feed management system. In the second analysis, adjusted sale price was set to equal nine commonly available performance variables. A stepwise regression resulted in 34.06 and 50.69 percent of the total variability in the sale price explained by the performance variables in the junior and senior tests, respectively. For the junior test, adjusted 365-day weight and frame score explained 32.19 percent of the variation and were highly significant (P \u3c .001). Average daily gain on-test, off-test age, and off-test weight added a combined 1.87 percent to the explained portion of variation. In the senior test however, average daily gain on-test and frame core explained 36.60 and 11.28 percent of the variation, respectively. The effects of these two variables were also highly significant (P \u3c .001). Adjusted 205-day weight, age off-test, and weight off-test added 2.81 percent to the explained portion in sale price. The variables age of dam, adjusted 365-day weight, weight per day of age and adjusted 365-day height in the senior test and age of dam, adjusted 205-day weight, weight per day of age and adjusted 365-day height in the junior test were not used in the forward selection procedure of the stepwise regression because they did not meet the preselected level of significance (P \u3c .10). Conclusions may be drawn that frame score and some level of gaining performance for a specified age were important traits when considering prospective herd sires. Also, age of dam had very little effect on the choice of herd sire and, weight per day of age and adjusted 365 day height were not considered when frame score and average daily gain on-test are available to the bull buyers. However, it is important to understand that bull buyers did utilize the performance data available to them when selecting prospective herd sires from test stations

Some investigations into the numerical solution of initial value problems in ordinary differential equations

PhD ThesisIn this thesis several topics in the numerical solution of the initial value problem in first-order ordinary diff'erentlal equations are investigated, Consideration is given initially to stiff differential equations and their solution by stiffly-stable linear multistep methods which incorporate second derivative terms. Attempts are made to increase the size of the stability regions for these methods both by particular choices for the third characteristic polynomial and by the use of optimization techniques while investigations are carried out regarding the capabilities of a high order method. Subsequent work is concerned with the development of Runge-Kutta methods which include second-derivative terms and are implicit with respect to y rather than k. Methods of order three and four are proposed which are L-stable. The major part of the thesis is devoted to the establishment of recurrence relations for operators associated with linear multistep methods which are based on a non-polynomial representation of the theoretical solution. A complete set of recurrence relations is developed for both implicit and explicit multistep methods which are based on a representation involving a polynomial part and any number of arbitrary functions. The amount of work involved in obtaining mulc iste, :ne::l'lJds by this technique is considered and criteria are proposed to Jecide when this particular method of derivation should be em~loyed. The thesis is conclud~d by using Prony's method to develop one-step methods and multistep methods which are exponentially adaptive and as such can be useful in obtaining solutions to problems which are exponential in nature

Entanglement-assisted local operations and classical communications conversion in the quantum critical systems

Conversions between the ground states in quantum critical systems via entanglement-assisted local operations and classical communications (eLOCC) are studied. We propose a new method to reveal the different convertibility by local operations when a quantum phase transition occurs. We have studied the ground state local convertibility in the one dimensional transverse field Ising model, XY model and XXZ model. It is found that the eLOCC convertibility sudden changes at the phase transition points. In transverse field Ising model the eLOCC convertibility between the first excited state and the ground state are also distinct for different phases. The relation between the order of quantum phase transitions and the local convertibility is discussed.Comment: 7 pages, 5 figures, 5 table

High-Frequency Spin Waves in YBa2Cu3O6.15

Pulsed neutron spectroscopy is used to make absolute measurements of the dynamic magnetic susceptibility of insulating YBa2Cu3O6.15. Acoustic and optical modes, derived from in- and out-of-phase oscillation of spins in adjacent CuO2 planes, dominate the spectra and are observed up to 250 meV. The optical modes appear first at 74 meV. Linear-spin-wave theory gives an excellent description of the data and yields intra- and inter-layer exchange constants of J_parallel =125 meV and J_perp = 11 meV respectively and a spin-wave intensity renormalization Z_chi = 0.4.Comment: postscript, 11 pages, 4 figures, Fig.2 fixe

Thermally stable low current consuming gallium and germanium chalcogenides for consumer and automotive memory applications

The phase change technology behind rewritable optical disks and the latest generation of electronic memories has provided clear commercial and technological advances for the field of data storage, by virtue of the many well known attributes, in particular scaling, cycling endurance and speed, that chalcogenide materials offer. While the switching power and current consumption of established germanium antimony telluride based memory cells are a major factor in chip design in real world applications, often the thermal stability of the device can be a major obstacle in the path to the full commercialisation. In this work we describe our research in material discovery and characterization for the purpose of identifying more thermally stable chalcogenides for applications in PCRAM

A Comparison of the High-Frequency Magnetic Fluctuations in Insulating and Superconducting La2-xSrxCuO4

Inelastic neutron scattering performed at a spallation source is used to make absolute measurements of the dynamic susceptibility of insulating La2CuO4 and superconducting La2-xSrxCuO4 over the energy range 15<EN<350 meV. The effect of Sr doping on the magnetic excitations is to cause a large broadening in wavevector and a substantial change in the spectrum of the local spin fluctuations. Comparison of the two compositions reveals a new energy scale of 22 meV in La1.86Sr0.14CuO4.Comment: RevTex, 7 Pages, 4 postscript figure