Search

Our ground-based measurements of martian atmospheric water vapor, made throughout L s = 34 ° to 249°, 24 September 1998 to 23 November 1999, during Mars year 24 (MY 24), show changes in Mars' humidity on hourly, daily, and seasonal timescales. We made concomitant measurement of nearby CO2 bands, and when possible, results were corrected for aerosol extinction using aerosol optical depths derived from our own CO2 analysis. Where there is spatial and temporal overlap, similar results are obtained for water vapor abundances and aerosol opacities as those observed from the Thermal Emission Spectrometer on Mars Global Surveyor. In addition some further discussion of our published earlier water vapor measurements (1991–1995) is included. Six results from this data set are: (1) the measured aerosol opacity in Mars atmosphere was variable but not greater than τ = 1 , with almost no clear atmosphere being observed, (2) measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a diurnal pattern with highest abundances at mid-day and low abundance in very early morning and late afternoon for some but not all measurements, (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends seen by instrumentation on the Mars Atmospheric Water Detector on the Viking Orbiters and by the Thermal Emission Spectrometer on Mars Global Surveyor, (4) there is a slight longitudinal correlation with the ground-ice observed by the Gamma Ray Spectrometer on Mars Odyssey, (5) there is evidence of the Low Southern Latitude Summer Minimum in our water vapor measurements but our data set for southern summer is limited, and (6) MY 24 appears to be wetter than MY 22 and MY 23.

Measurements of martian atmospheric water vapor made throughout L s = 18.0°–146.4° (October 3, 1996–July 12, 1997) show changes in Mars humidity on hourly, daily, and seasonal time scales. Because our observing program during the 1996–1997 Mars apparition did not include concomitant measurement of nearby CO 2 bands, high northern latitude data were corrected for dust and aerosol extinction assuming an optical depth of 0.8, consistent with ground-based and HST imaging of northern dust storms. All other measurements with airmass greater than 3.5 were corrected using a total optical depth of 0.5. Three dominant results from this data set are as follows: (1) pre- and post-opposition measurements made with the slit crossing many hours of local time on Mars’ Earth-facing disk show a distinct diurnal pattern with highest abundances around and slightly after noon with low abundances in the late afternoon, (2) measurements of water vapor over the Mars Pathfinder landing site (Carl Sagan Memorial Station) on July 12, 1997, found 21 ppt μm in the spatial sector centered near 19° latitude, 36° longitude while abundances around the site varied from as low as 6 to as high as 28 ppt μm, and (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends.

The occultation of bright star HIP9369 by the northern polar region of Jupiter was observed from four locations in North and South America, providing four data sets for ingress and egress. The inversion of the eight occultation lightcurves provides temperature profiles at different latitudes ranging from 55°N to 73.2°N. We estimate the errors on the profiles due to the uncertainties of the inversion method and compare the value of the temperature at the deepest level probed (∼ 50 μbar) with previous observations. The shape of the temperature gradient profile is found similar to previous investigations of planetary atmospheres with propagating and breaking gravity waves. We analyze the small scale structures in both lightcurves and temperature profiles using the continuous wavelet transform. The calculated power spectra of localized fluctuations in the temperature profiles show slopes close to −3 for all eight profiles. We also isolate and reconstruct the three-dimensional geometry of a single wave mode with vertical and horizontal wavelengths of respectively 3 and 70 km. The identified wave is consistent with the gravity wave regime, with a horizontal phase speed nearly parallel to the planetary meridian. Nevertheless, the dissipation of the corresponding wave in Jupiter’s stratosphere should preclude its detection at the observed levels and an acoustic wave cannot be ruled out.

Blooms of cyanobacteria or blue-green algae are known to have caused poisoning in fish, waterfowl, animals and man. One of the toxins responsible for this is the hepatotoxin microcystin-LR which has been found to occur in blooms present intermittently in sources used for domestic water supplies. Three sets of experiments were undertaken to investigate the acute toxicity of microcystin-LR in mice and rats by the oral and intraperitoneal routes, the potential for effects on foetal development in the mouse, and the effects of repeated oral dosing over 13 weeks in the mouse. The results of this work were as follows: (1) Microcystin-LR is 30-100 times less toxic via oral ingestion than via intraperitoneal injection; (2) Microcystin-LR is not a selective developmental toxicant in the mouse. There was a No Observed Adverse Effect Level (NOAEL) of 600 μg kg-1 bodyweight per day given on days 6-15 of pregnancy for any form of developmental toxicity; (3) There was a clear NOAEL for tissue damage in the liver of 40 μg kg-1 bodyweight per day of microcystin-LR. Using this data, a value of 1 μg l-1 microcystin-LR would be an appropriate guideline value for drinking water.

Europa, one of the satellites of Jupiter, has long been thought to be a dormant icy body, unlike its volcanically active neighbour, Io. Europa lies deep within Jupiter's magnetosphere, however, and is continuously bombarded by energetic ions, which modify the surface ices and are probably responsible for creating Europa's tightly bound oxygen atmosphere. Here we report the discovery of an atmosphere of atomic sodium that extends to at least 25 times Europa's radius. We suggest that this sodium is originally released by Io's volcanoes, after which it is ionized in the magnetosphere and implanted into Europa's surface ice; subsequent sputtering of the ice by magnetospheric ions releases the sodium to form the extended atmosphere. Although sodium is a minor constituent of Europa's atmosphere, it traces the distribution of the major atmospheric components which are not themselves directly observable. The sodium and oxygen could represent the extremes of the distribution of the atmospheric components, with only the heaviest molecules (such as the oxygen) being tightly bound; alternatively the sodium might be in the form of an extended corona, analogous to Io's atmosphere.

Smith-Lemli-Opitz syndrome, a syndrome of multiple malformations and mental retardation that for years was relegated to the atlases of genetic esoterica, was recently found to be a relatively common inborn error of metabolism. The underlying defect is absent or deficient activity of 7-dehydrocholesterol- delta 7-reductase, the enzyme catalysing the final step of cholesterol synthesis. The discovery of the biochemical defect causing Smith-Lemli-Opitz syndrome has resulted in the development of a diagnostic test and a potentially beneficial treatment (dietary cholesterol supplementation). Infants and young children with the syndrome have shown marked improvement in growth, behaviour and general health after receiving cholesterol therapy; older children and adults have shown some improvement in development and intellectual functioning. Despite the excitement these developments have elicited among geneticists and biochemists, this syndrome remains relatively unknown to many primary care physicians. Increased awareness of Smith-Lemli-Opitz syndrome is needed to identify affected patients so that they and their families can benefit from appropriate treatment and genetic counselling.

SummaryThe term game is applied to those wild animals which are pursued in the chase or kept for pleasure. When an animal has been domesticated it belongs to the family, lives in or near the habitations of man and is tame, not wild.Wild African buffalo, eland, oryx and gazelle were caught by either dart-immobilization, chasing and roping, or driving into a corral. Weaned, sub-adult animals were preferred. The taming procedures started in small, dark, padded cells and progressed through a series of larger enclosures until the animals were grazing in a 40 ha paddock 7 weeks after capture. Gazelle was the only species which was not established as a domestic herd by this method, because of its liability to self-inflicted injuries.The domestic game animals were grazed over thousands of hectares without fencing, but under supervision of herdsmen. They were subjected to standard domestic animal husbandry procedures including eartagging, dehorning and castration.The conclusion is that some African game animals are easy to domesticate as has also been demonstrated in the prehistoric and recent past. The reason they have not displaced conventional livestock can be found in the history of domestication. The condition originated in the Middle East and spread mainly by the introduction of an alien culture and livestock to Africa. The time when sub-Saharan Africans had established a suitable way of life for domestication coincided with the arrival of cattle, sheep and goats forced south by the desiccating environment.The potential of African game animals to domestic animal production will be evaluated in subsequent papers.

SUMMARYFishmeal, soya-bean meal and urea were compared as nitrogen sources in diets rich in fibre for yearling cattle, using feeding trials and digestibility and nitrogen retention studies. All animals were individually fed. Diets supplemented with fishmeal supported the highest rates of daily live-weight gain and nitrogen retention. There was no response in dry-matter intake and digestibility from extra nitrogen, either from fishmeal or urea, when the crude protein of the diet was 8·5% or over, and a small response in digestibility when soya-bean meal was used.Molar proportions of VFA, rumen NH3-N concentrations and blood urea nitrogen concentrations were all affected by both amount and source of nitrogen supplementation. Multiple regression analysis showed the undegradable protein supply to be more critical with high than with low fibre diets.

The Los Alamos Meson Physics Facility (LAMPF) operated with simultaneous H+ and H- beams until June 1980, when a method of providing a variable energy H- beam as well as a full-energy H+ beam was brought into use. The scheme is based on time sharing between H+ and H- beam pulses. It is now possible to provide H- beams with energy as low as 300 MeV along with the usual 800-MeV H+ beams. The method requires a reduction in duty factor of the H+ and H- beams; however, the total duty factor has been increased to 9% which compensates in large measure for the reduction due to dual-energy operation. The necessary modifications to the beam switchyard and accelerator timing systems are described.

The acoustic pressures produced by a band of noise were measured at the entrance to the auditory canal and near the tympanum. The stimuli was produced by a TDH‐39 earphone activated by a noise band tailored to produce an approximately flat spectrum between 0.1 and about 4 kHz at the entrance to the ear canal. A computer program calculated the output power spectra, the signal/noise, the cross‐power spectrum, the transfer function, the coherence function, and the phase between the input and output power spectra. The transfer function in each animal shows an upper frequency peak, the location of which varies with the apparent volume of the canal, being highest for the guinea pig and lowest for man. The magnitude of the resonance is largest for the cat and smallest for the guinea pig. [Supported in part by DAMD 17‐78C‐8067 and NSF‐77‐16907.]

High‐intensity, low‐frequency octave band noise in the free field has been reported to produce permanent threshold shift at 2 kHz in chinchillas [Burdick, Patterson, Mozo, and Camp, J. Acoust. Soc. Am. 64, 458 (1978)]. We have delivered 100‐ and 250‐Hz low‐pass noise to the chinchilla with intact pinna but open bulla and have measured the spectrum of the CM recorded with electrodes in turn I and turn II. SPL's were measured at the pinna. The output of the microphone was led to channel 1 of an A/D converter. The CM was led to channel 2. The inputs to the A/D's were adjusted to the same rms level to minimize digital noise. A computer program calculated FFT's and produced several calculations from them (see previous abstract). At SPL's below 100 dB, the output spectrum (CM) is similar to the input spectrum (microphone). Above 100 dB the output spectrum contains frequencies above the passband of the input spectrum. The coherence function indicates that the high‐frequency output is not present in the input power spectrum. [Supported in part by DAMD17‐78C‐8067 and NSF 77‐16907.]