Deuterium on Mars: The Abundance of HDO and the Value of D/H

Deuterium on Mars has been detected by the resolution of several Doppler-shifted lines ofHDO near 3.7 micrometers in the planet's spectrum. The ratio of deuterium to hydrogen is (9 +/- 4) x 10(-4); the abundance of H(2)0 was derived from lines near 1.1 micrometers. This ratio is enriched on Mars over the teiluric value by a factor of6 +/- 3. The enrichment implies that hydrogen escaped more rapidly from Mars in the past than it does now, consistent with a dense and warm ancient atmosphere on the planet.     

Large magnetic anisotropy of a single atomic spin embedded in a surface molecular network

Magnetic anisotropy allows magnets to maintain their direction of magnetization over time. Using a scanning tunneling microscope to observe spin excitations, we determined the orientation and strength of the anisotropies of individual iron and manganese atoms on a thin layer of copper nitride. The relative intensities of the inelastic tunneling processes are consistent with dipolar interactions, as seen for inelastic neutron scattering. First-principles calculations indicate that the magnetic atoms become incorporated into a polar covalent surface molecular network in the copper nitride. These structures, which provide atom-by-atom accessibility via local probes, have the potential for engineering anisotropies large enough to produce stable magnetization at low temperatures for a single atomic spin.     

Midwest (U.S.A.) reservoir water quality modification

The impact of a flood control, low flow argumentation reservoir in the Midwestern part of the United States on BOD, COD, and ammonia was evaluated in this paper. Fifteen years of weekly water quality data (9 yr before impoundment and 6 yr after impoundment) from four sampling stations upstream and downstream of the reservoir were available for analysis. The annual loading rates of these parameters (kg ha^?1 vr^?1) were found to correlate well with annual runoff (cm yr^?1). Besides, the reservoir was found to have had a significant and beneficial impact on the downstream loading rates of BOD and COD, which were reduced by 55 and 75%, respectively. As for ammonia, the results of this study indicate that its annual loadings at downstream locations were not significantly affected by the reservoir. Average non-point source contributions of BOD and ammonia loadings into the system were found to be about 80 and 55%, respectively.     

Preliminary biochemical observations of fishes inhabiting an acidified lake in Ontario,Canada

Blood serum and other tissues of white suckers (Catostomus commersoni) and other species of fish have been examined in a preliminary effort to understand losses of fish from acid lakes. Maturing females of highly acid George Lake failed to show the normal degree of increase in serum Ca over males captured in the same location. Elevated serum Ca was always observed in females, relative to males, from non-acid locations when maturation stages were similar. A number of body tissues were examined to determine whether the distributions of Ca or other elements were altered and the only striking change evident in fish from George Lake was their high Mn content. Bone in particular was examined for N, Na, Mg, P, K, and Ca and no evidence of demineralization was found. Other tests such as hemoglobin indicated that an anticipated adaptive response to asphyxia was absent. Our results indicate that potential mechanisms of fish losses such as asphyxia and starvation are unlikely to have been significant, however, they do not firmly establish any alternate mechanism. As a working hypothesis we suggest that Ca dynamics may limit ovarian development and that absorption of this metal at exchange surfaces may be impaired.     

Plasma amylin and insulin concentrations in normoglycemic and hyperglycemic cats.

The recently discovered pancreatic peptide amylin is postulated to be involved in the pathogenesis of feline diabetes mellitus. However, plasma amylin concentrations in normal and diabetic cats have not yet been published. The aim of the present study was to validate a commercial amylin radioimmunoassay kit for the measurement of feline amylin in unextracted plasma, and to measure plasma amylin concentrations in normal and diabetic cats. The kit had satisfactory specificity, sensitivity, accuracy, and precision, and can be recommended for measurement of feline amylin in unextracted EDTA plasma, when nonspecific binding of plasma samples is used in the calculation of measured amylin concentration. Fasting amylin concentration in cats with normal glucose tolerance was 97 +/- 4 pmol/L. Plasma amylin increased in parallel with insulin after glucose administration in cats with normal and impaired glucose tolerance. In contrast to cats with normal glucose tolerance, cats with impaired glucose tolerance had markedly delayed amylin and insulin secretion. Diabetic cats had basal hypoinsulinemia combined with hyperamylinemia. Hyperamylinemia may lead to reduced insulin secretion and insulin resistance, and contribute to the development of feline diabetes. In conclusion, feline amylin can be measured in unextracted EDTA plasma. Fasting amylin concentrations are approximately 100 pmol/L, and amylin and insulin are cosecreted in cats with normal and impaired glucose tolerance. Increased amylin concentrations may contribute to the development of feline diabetes mellitus.     

Course of feline leukemia virus infection and its detection by enzyme-linked immunosorbent assay and monoclonal antibodies

Monoclonal antibodies specific for 3 distinct epitopes of the species-specific determinants of feline leukemia virus (FeLV) p27 were used in an enzyme-linked immunosorbent assay (ELISA) for measurement of serum p27 in cats infected with FeLV. Group-specific antigen (GSA) of FeLV in peripheral blood leukocytes was also determined by an immunofluorescence assay. Antibodies to FeLV and the feline oncornavirus-associated cell membrane antigen (FOCMA) were also measured. Thirty-six cats were surveyed and assigned to 4 categories. Five developed persistent viremia (category 1), characterized by continuous expression of p27, GSA, and low antibody titers to FeLV and FOCMA. Eleven cats with transient viremia (category 2) and 13 cats that were never detectably viremic (category 3), as judged by absence of GSA and p27, developed increased antibody titers to FeLV and FOCMA. Seven cats were never viremic, as judged by the GSA in the peripheral blood leukocytes, but still had detectable serum p27 (category 4). Most category 4 cats developed high antibody titers against FOCMA and/or FeLV. Of 307 field cats examined, 7% of the healthy cats and 10% of the sick cats could be assigned to category 4. However, this difference was not significant (P greater than or equal to 0.05). Of 26 cats with neoplasms 2 (1 of 12 with lymphosarcoma) could be classified as category 4. Because virus could be isolated from 2 category 4 cats, they were considered immune carriers.     

Prevalence of feline calicivirus, feline leukaemia virus and antibodies to FIV in cats with chronic stomatitis

The prevalence of feline calicivirus (FCV), feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) antibodies were assessed in 78 British and 18 North American household cats with chronic stomatitis and in appropriate controls. In British cats, FCV was significantly (P less than 0.005) more prevalent in both hospital (92 per cent) and general practice (79 per cent) cases compared to their controls (19 per cent in both cases). A similar difference in prevalence of FCV was noted in North American cats where 50 per cent of cases were positive compared to 0 per cent of controls (P less than 0.01). FeLV prevalence was low in all chronic stomatitis populations. A significantly higher prevalence of antibody to FIV was found in British hospital cases (81 per cent) compared with time-matched controls (16 per cent) (P less than 0.001): a similar rate was found in the general practice cases (75 per cent) for which no controls were available. In the North American sample, FIV antibody status was similar in cases (54 per cent positive) and their age, sex and breed matched controls (50 per cent). The possible role of FCV and FIV in the pathogenesis of feline chronic stomatitis is discussed.