Time and energy dependence of the cosmic ray gradient in the outer heliosphere

Pioneers 10 and 11, now 35 and 18 AU from the Sun, continue to extend our knowledge of the spatial dependence of cosmic ray intensities in the heliosphere. Radial gradients measured from these spacecraft by UCSD detectors which have integral energy responses above thresholds of 80 and 500 MeV/nucleon are reported. An average gradient of 2%/AU typifies the data set as a whole, but there are time and energy dependences that deviate from this value. With operating lifetimes of 13 and 12 years, respectively, for the two spacecraft, the time dependence was followed for over a solar cycle. The higher energy channel shows less modulation on all time scales. At the start of the present cycle, the gradient is lower than the average value during the last solar cycle

Structure and screening in molecular and metallic hydrogen at high pressure

A variational wavefunction is used to express the (spin restricted) Hartree-Fock energy as reciprocal lattice sums for static lattice FCC monatomic hydrogen and diatomic Pa3 molecular hydrogen. In the monatomic phase the hydrogenic orbital range closely parallels the inverse Thomas-Fermi wavevector; the corresponding energy E has a minimum of -0.929 Ryd/electron at r sub s = 1.67. For the diatomic phase E(r sub s) is similar, but the constituent energies, screening, and bond length reflect a qualitative change in the nature of the solid at r sub s = 2.8. This change is interpreted in terms of a transition from protons as structural units (at high density) to weakly interacting models (at low density). Insensitivity of the total energy to a rapid fall in the bond length suggests association with the rotational transition where the rapid molecular orientations characteristic of high pressures disappear and the molecules rotate freely at low pressure

Gait characteristics of subjects with chronic fatigue syndrome and controls at self-selected and matched velocities

Background: Gait abnormalities have been reported in individuals with Chronic Fatigue Syndrome (CFS) however no studies exist to date investigating the kinematics of individuals with CFS in over-ground gait. The aim of this study was to compare the over-ground gait pattern (sagittal kinematics and temporal and spatial) of individuals with CFS and control subjects at their self-selected and at matched velocities. Methods: Twelve individuals with CFS and 12 matched controls participated in the study. Each subject walked along a 7.2 m walkway three times at each of three velocities: self-selected, relatively slow (0.45 ms-1) and a relatively fast (1.34 ms-1). A motion analysis system was used to investigate the sagittal plane joint kinematics and temporal spatial parameters of gait. Results: At self-selected velocity there were significant differences between the two groups for all the temporal and spatial parameters measured, including gait velocity (P = 0.002). For the kinematic variables the significant differences were related to both ankles during swing and the right ankle during stance. At the relatively slower velocity the kinematic differences were replicated. However, the step distances decreased in the CFS population for the temporal and spatial parameters. When the gait pattern of the individuals with CFS at the relatively fast walking velocity (1.30 ± 0.24 ms-1) was compared to the control subjects at their self-selected velocity (1.32 ± 0.15 ms-1) the gait pattern of the two groups was very similar, with the exception of both ankles during swing. Conclusion: The self-selected gait velocity and/or pattern of individuals with CFS may be used to monitor the disease process or evaluate therapeutic intervention. These differences may be a reflection of the relatively low self-selected gait velocity of individuals with CFS rather than a manifestation of the condition itself

Lipid Coated Gold Nanoparticle Cores: Synthesis and Characterization

Including environmental, industrial, and biomedical sciences, applications of gold nanoparticles are on the forefront of research in many areas. By altering the surface treatment of spherical gold nanoparticle cores, particularly those smaller than 100 nm (nanometers), one can influence their potential use in a number of ways. Lipid coated nanoparticles with specifically selected surface ligands can be used for multiple biomedical functions, including medical imaging, for use as colorimetric and plasmonic sensors within the body, and as cell or organelle specific targets for therapeutic drug delivery or cancer treatment. Here, spherical gold nanoparticles ranging in size from 8-40 nm (avg. diameter 23-48 nm) have been synthesized and coated with poly(allylamine hydrochloride) (PAH) and a mixed lipid solution of 1:1 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and lysophosphatidylcholine (LPC), two of the four major types of lipids found in the human body. Characterization was performed using a NanoSight LM10HS particle sizer, and shows a gradual increase in size after each step in the coating process for nanoparticle cores ranging in size from 16-27 nm. The thickness of these purified and lipid coated nanoparticles was consistently 2-3 times that of the PAH coated sample it was layered onto, suggesting a successful, multi-layered coat that ranges in size based on the PAH coated core size. UV-Vis spectroscopy shows a slight red shift, indicating an increase in size and change in refractive index, which supports the presence of lipid coating on the PAH coated gold nanoparticle cores

Long-term Effects of Tillage on the Retention and Transport of Soil Water

Quantitative measurements were made of the physical and chemical properties of two virgin prairie soils, Crowley and Jay, that remain in their native Arkansas environments and of similar soils that had been tilled extensively. Comparisons were made of soil properties at several depths. When compared with the tilled soils the virgin soils had higher organic matter contents, saturated hydraulic conductivities and water retained at several applied pressures. Bulk densities and hydraulic resistances were lower in the virgin soils. For the Crowley silt loam, values of pH and elemental contents of the virgin soil were higher than those of the tilled soil. Determinations also were made of the effects of a 14-year addition of winter cover crops on a Dubbs-Dundee soil in continuous cotton production. In general, the winter cover crops tended to increase hydraulic conductivity~. ·porosity and organic matter content. These results indicated that the detrimental effects of long-term tillage on soil hydraulic properties could partially be overcome with the planting of these crops during the winter. However, the rate of improvement in the hydraulic properties was not dramatic

Studies on the Neuromuscular Anatomy and Physiology of the Stick Insect, Carausius morosus Br. (Cheleutoptera)

1. The anatomy and innervation of the coxal and femoral muscles of the pro- and metathoracic legs have been described. The pattern of nerves and muscles is similar in both legs. 2. Histological examination has shown that the motor nerve endings on the flexor tibialis muscle fibres of the prothoracic leg are of the "Doyere-cone" type, and are spaced at intervals of approximately 60 u along the length of the fibres. 3. The electrical responses of the fibres of the flexor tibialis muscle have been examined with the aid of glass capillary intracellular microelectrodes. Records have also been made of some of the mechanical responses of this muscle. 4. Two types of electrical responses are presents "fast", non-facilitating responses resembling the action potentials of vertebrate muscles, and associated with quick twitch-type contractions of the muscle fibres; and "slow", readily facilitating responses resembling small end-plate potentials, associated with slow smooth movements and maintenance of the tonus of the muscle. 5. The two responses are produced by two separate types of motor axons innervating the muscle. 6. The muscle is capable of developing a tetanus p tension of 800 g./cm2./unit cross-sectional area of individual fibres. The tetanus/twitch ratio is high. 7. Pharmacological substances which alter vertebrate neuromuscular transmission do not affect the fast response. 8. Progressively lowered temperatures lengthen the time course and to a slight extent the size of the "fast" response, and an inflexion appears in the rising phase which was taken to indicate that the "fast" response consists of two components, a junctional potential and an active membrane response. 9. Refractoriness occurs in the decay phase of the "fast" response. A pair of stimuli sufficiently close together will produce effects which summate to give an enhanced junctional potential. A similar effect was not observed in the case of the active membrane response. 10. Analyses of its blood ionic composition have confirmed that Carausius is a typical herbivorous insect, with blood sodium/potassium and calcium/magnesium ratios of less than unity. 11. The effects of changing the sodium, potassium, calcium and magnesium concentrations of the bathing fluid on the "fast" response have been studied. 12. Lowering the sodium concentration results in a decrease in the magnitudes of the resting and action potentials, but an active membrane response is present in zero sodium. The rate of rise of the action potential increases as the sodium concentration is raised. 13. When tetramethylammonium ions are substituted for sodium ions in the bathing fluid, variations in the magnitudes of the resting and action potentials similar to those seen in the corresponding sodium salines are observed; but the rate of rise decreases as the TMA level is raised. 14. It is suggested that sodium ions are not essential for the production of an active membrane response, but that they may affect the excitability of the muscle fibre membrane. 15. Calcium ions are necessary for the development of the junctional potential. It is suggested that they influence the liberation of a neuromuscular transmitter substance. They may also affect the sodium permeability of the membrane. 16. When the magnesium concentration is raised above about 150 m. equiv. per litre, the action potential declines in size, and neuromuscular block eventually results. This effect is not antagonized by calcium ions. 17. The action potential also declines in size when the magnesium concentration is lowered below about 100 m. equiv. per litre. The resting potential is not affected by magnesium ions. 18. The resting potential is directly proportional to the log. of the potassium concentration except at low concentrations. 19. These results are discussed in the light of similar work on vertebrates and other arthropods. In particular, it is considered that the fast response is produced by a process similar to vertebrate and locust neuromuscular transmission, but that the sodium and magnesium results represent adaptations to a herbivorous habitat; and the possibility that a selective ion barrier is present around the muscle fibres of Carausius is considered and rejected, with reservations in the case of sodium ions

Project management in the Apollo program Interim report

Project management in Apollo progra

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