Modeling interannual variability in the Martian seasonal CO2 cycle

One aspect of the seasonal pressure variations measured at the Viking Lander sites is their nearly perfect interannual repeatability. This presents a problem because it implies that the behavior of the seasonal polar caps should be highly repeatable from year to year as well. There are a number of observations and theories suggesting that the presence of dust and water ice clouds in the Martian atmosphere should have significant direct and indirect effects on the rates of CO2 condensation and sublimation in the north and south polar regions. These effects include (1) reduced rates of CO2 frost condensation during polar night seasons due to the radiative effects of dust and water ice clouds and associated CO2 clouds or elevated atmospheric temperatures and (2) reduced or elevated rates of frost sublimation due to the radiative effects of atmospheric dust or to changes in frost emissivities and albedos due to contamination by water ice and dust. The Viking Landing pressure observations are examined to determine the range and character of the interannual variations present. Then a diurnal and seasonal thermal model is used to examine the effects of interannual variations in the polar heat balance on seasonal pressure variations

Project management in the Apollo program Interim report

Project management in Apollo progra

A microcontroller system for investigating the catch effect: Functional electrical stimulation of the common peroneal nerve

Correction of drop foot in hemiplegic gait is achieved by electrical stimulation of the common peroneal nerve with a series of pulses at a fixed frequency. However, during normal gait, the electromyographic signals from the tibialis anterior muscle indicate that muscle force is not constant but varies during the swing phase. The application of double pulses for the correction of drop foot may enhance the gait by generating greater torque at the ankle and thereby increase the efficiency of the stimulation with reduced fatigue. A flexible controller has been designed around the Odstock Drop Foot Stimulator to deliver different profiles of pulses implementing doublets and optimum series. A peripheral interface controller (PIC) microcontroller with some external circuits has been designed and tested to accommodate six profiles. Preliminary results of the measurements from a normal subject seated in a multi-moment chair (an isometric torque measurement device) indicate that profiles containing doublets and optimum spaced pulses look favourable for clinical use

Thermal Properties of a Simulated Lunar Material in Air and in Vacuum

Thermal properties of simulated lunar material in air and in vacuu

Manned space flight in transition

A study was conducted to analyze the reorientation of NASA programs in the post-Apollo period. The study is an external view of NASA by unbiased observers as an input to and aid in the decision making process concerning near and long term planning. The subjects discussed are: (1) the near-term NASA scenario; (2) organization of field centers; (3) planning activities; and (4) operational activities. A summary of the recommendations arising as a result of the study is presented

The platinum nuclei: concealed configuration mixing and shape coexistence

The role of configuration mixing in the Pt region is investigated. For this chain of isotopes, the nature of the ground state changes smoothly, being spherical around mass $A\sim 174$ and $A\sim 192$ and deformed around the mid-shell N=104 region. This has a dramatic effect on the systematics of the energy spectra as compared to the systematics in the Pb and Hg nuclei. Interacting Boson Model with configuration mixing calculations are presented for gyromagnetic factors, $\alpha$-decay hindrance factors, and isotope shifts. The necessity of incorporating intruder configurations to obtain an accurate description of the latter properties becomes evident.Comment: Accepted in Physical Review

Marginal states of the resistive tearing mode with flow in cylindrical geometry

The linear stability of tearing modes in a cylindrical plasma subject to a sub-Alfvénic equilibrium shear flow along the equilibrium magnetic field is considered. The equations in the resistive boundary layer at the rational surface are solved numerically using a Fourier transform combined with a finite-element approach. The behaviour of the growth rate as a function of the flow and the various parameters (including a perpendicular fluid viscosity) is obtained. Marginal stability curves showing the dependence of the familiar matching parameter Δ' with flow and shear are also given

Halogenated diazines and triazines

PART I A convenient synthesis of 3, 5, 6-trichloro-1, 2, 4-trlazme was developed using 3, 5-dihydroxy-1, 2, 4-triazine and 6-bromo-3, 5-dihydroxy- 1, 2, 4-triazine as precursors. No product was obtained on photolysis of 3, 5,6-trichloro-1,2 ,4-tnazine but nitrogen elimination occurred on pyrolysis to give trichloroacrylonitrile the red colouration from the pytolyzate (at -196 ) was deduced to be from trichloroazetc. This reaction is the first evidence of azete generation from a 1, 2, 4-triazine. The fluorination of 3, 5, 6-Lrichloro-1, 2,4-triazmc was attempted with potassium and caesium fluorides, with and without a solvent 3,5,6-Trifluoro-1 ,2,4-triizine was formed in many of the reactions but was always detected as a minor product in unstable mixtures. Polyfluoroalkylations of 3, 5, 6-trichloro-1, 2, 4-triazine were attempted with tetiafluoroethylene, hexaluoropropene , n-octafluorobut-2 enc and hexafluorocyclobutene. Alkylation was successful only with hexafluoropropene where perfluoro-3, 5, 6-tris-isopropy1-1, 2, 4-triazine was prepared in good yields. Attempts to prepare mono- and di-alkyl derivatives were unsuccessful. Photolysis of perfluoro-3,5,6-tris-isopropy 1-1,2,4-triazine gave three products, perfluoro-isobutyronitrile and perfluoro-2,5-dimethylhex-3-yne by nitrogen elimination and perfluoro-2,4,6-tris-isopropy1-1,3,5-triazine by rearrangement. Pyrolysis gave nitrogen elimination but there was no evidence of any azete formation. PART II The novel cyclisation observed with 4,6-bis-dimcthylamino-3,5-bis-heptafluoroisopropyipyridazine was studied. A process of internal nucleophilic substitution occurred, with elimination of hydrogen fluoride, to give a product with an ambiguous bicyclic structure. The vivid purple coloured intermediate formed on loss of fluoride ion was trapped as a tetrafluoroborate salt. In an aid to determine the structure of the bicyclic product, various dimethylamino heptafluoroisopropylpyridazines were prepared