Cathodoluminescence of natural, plastically deformed pink diamonds.

The 49 type I natural pink diamonds examined exhibit color restricted to lamellae or bands oriented along {111} that are created by plastic deformation. Pink diamonds fall into two groups: (1) diamonds from Argyle in Australia and Santa Elena in Venezuela are heavily strained throughout and exhibit pink bands alternating with colorless areas, and (2) diamonds from other localities have strain localized near the discrete pink lamellae. Growth zones are highlighted by a blue cathodoluminescence (CL) and crosscut by the pink lamellae that emit yellowish-green CL that originates from the H3 center. This center probably forms by the recombination of nitrogen-related centers (A-aggregates) and vacancies mobilized by natural annealing in the Earth's mantle. Twinning is the most likely mechanism through which plastic deformation is accommodated for the two groups of diamonds. The plastic deformation creates new centers visible through spectroscopic methods, including the one responsible for the pink color, which remains unidentified. The differences in the plastic deformation features, and resulting CL properties, for the two groups might correlate to the particular geologic conditions under which the diamonds formed; those from Argyle and Santa Elena are deposits located within Proterozoic cratons, whereas most diamonds originate from Archean cratons.

The widespread distribution of a novel silica polymorph in microcrystalline quartz varieties.

An x-ray examination of more than 150 specimens of fine-grained quartz varieties from around the world has revealed that more than 10% and as much as 80% of the silica in many samples is actually moganite, a little-known silica polymorph. Rietveld refinements of 50 powder x-ray diffraction patterns produced by fibrous quartz (agate, chalcedony) and nonfibrous quartz (chert, flint) indicate that the concentrations of moganite within each subgroup are widely distributed. The large amount of moganite (>30%) found in cherts from arid, alkaline environments may resurrect length-slow silica as an indicator of evaporitic regimes, and the absence of moganite in weathered and hydrothermally altered silica samples may be a useful measure of fluid-rock interaction.

Virus isolation test for feline leukemia virus.

A method was developed for detecting feline leukemia virus (FeLV) infection in cats by coculturing separated blood lymphocytes and platelets with clone 81 cells carrying a murine sarcoma genome but free of leukemia virus (S+L-). FeLV caused cell transformation that was easily visible 3-12 days after infection. This method is simple, sensitive, and easily read; it has the advantage of directly detecting infectious FeLV rather than viral antigens.

Cardiovascular effects and changes in midbrain periaqueductal gray neuronal activity induced by electrical stimulation of the hypothalamus in the rat.

The effects of low-intensity electrical stimulation of sites in the hypothalamus and zona incerta (ZI) on mean blood pressure (MBP), heart rate (HR), and neuronal activity in the midbrain periaqueductal gray (PAG) were investigated in rats. Long-lasting depressor responses were elicited from 67 sites in the hypothalamus and ZI. Effects on HR were variable, except for the ZI where bradycardiac responses were evoked. The amplitude of the depressor responses was significantly correlated with baseline MBP on stimulation of the dorsomedial hypothalamic nucleus (DMH) or the dorsal hypothalamic area. Extracellular single-unit recordings were made from 94 PAG neurons. Most units were located in the ventral half of the PAG (62/94), where spontaneous firing rates were significantly higher than in the dorsal half: 12.5 +/- 1.4 spikes/s as compared to 6.0 +/- 0.9 spikes/s. Changes in PAG neuronal activity to both ipsi- and contralateral hypothalamic stimulation were observed. Most neurons were inhibited or unresponsive. There was no site specificity: responsive and unresponsive neurons were scattered throughout the PAG. Inhibition was most effectively evoked by stimulation of the DMH (25 out of 39 neurons) and the ZI (9 out of 15 neurons). In most neurons, the inhibition strictly followed the time course of hypothalamic stimulation. The results suggest that PAG as well as nonPAG pathways participate in the hypothalamic control of cardiovascular function.

Borreliosis in equids in northeastern United States.

During 1982 and 1985, blood samples from 705 equids were examined for antibodies to Borrelia burgdorferi. By indirect immunofluorescence staining, IgM and total immunoglobulin (IgM and IgG) antibodies were detected in 37 (5.3%) and 90 (12.8%) serum specimens, respectively. The geometric mean titer for IgM antibody (140.4) was highest during July, whereas total immunoglobulin ranged from 94.1 in October to 338 in May. Eighty-six equids with total immunoglobulin to B burgdorferi lived in areas of Connecticut where the primary tick vector, Ixodes dammini, was present. Of the 86 equids, 9 from Lyme, Connecticut and Westchester County, New York had antibodies to B burgdorferi and developed limb or joint disorders that resulted in single or recurrent episodes of lameness.

Antibiotic susceptibility profiles for mastitis treatment.

Susceptibility tests were performed on milk samples representing prevalent mastitis infections in certain herds. Susceptibility patterns of the same bacterial species from several mastitis infections in the same herd were consistent. The herd antibiotic susceptibility profiles were used as a basis for selecting antibiotics for treatment of all such mastitis cases in that herd. A high degree of correlation was seen between the susceptibility test results and treatment results. Susceptibility patterns of the same bacterial species from mastitis infections in different herds varied greatly, which indicated that any one antibiotic would not work equally well against the same bacterial infection in every herd. Therefore, treatment should be selected on the basis of susceptibility test results. When both Streptococcus and Staphylococcus mastitis occurred in the same herd, the susceptibility patterns for the 2 bacterial species varied widely. Therefore, for herds that experienced both streptococcal and staphylococcal mastitis, antibiotics to which both bacterial species were susceptible were used for treatment.

Isolation of Leptospira interrogans serovar grippotyphosa from the skin of a dog.

Leptospira interrogans serovar grippotyphosa was isolated from the skin of a 14-year-old male dog with deteriorating health. Necropsy revealed numerous lesions characteristic of aged dogs, but no evidence of acute hepatitis or nephritis, which are common features of pathogenic Leptospira infections. Antibody to Leptospira was not detected in the dog's serum by microagglutination. Leptospires grew slowly in Barbour-Stoenner-Kelly medium, a medium commonly used to isolate Borrelia, but then grew abundantly in Tween 80-bovine albumin leptospire medium. The isolate was pathogenic to a hamster and was identified by microagglutination and restriction endonuclease analysis.

Business, society, and the Reagan revolution.

When Ronald Reagan first came to power two years ago, many Americans believed that his administration would bring about dramatic and fundamental changes in American politics. In this paper, the author contends that although it is still too early to fully assess the effects of "Reaganism" on the country in general, it is not too early to evaluate the results in terms of the altered relationships between government, business, and society. The author goes on to say that the 1982 congressional election results already show that the American people are fast becoming disillusioned with the Reagan administration. In conclusion, the author maintains that only when the U.S. chooses a visionary leader who is capable of defining--or redefining--"progress." will American politics undergo a real revolutionary change.

Manganese oxide minerals: crystal structures and economic and environmental significance.

Manganese oxide minerals have been used for thousands of years-by the ancients for pigments and to clarify glass, and today as ores of Mn metal, catalysts, and battery material. More than 30 Mn oxide minerals occur in a wide variety of geological settings. They are major components of Mn nodules that pave huge areas of the ocean floor and bottoms of many fresh-water lakes. Mn oxide minerals are ubiquitous in soils and sediments and participate in a variety of chemical reactions that affect groundwater and bulk soil composition. Their typical occurrence as fine-grained mixtures makes it difficult to study their atomic structures and crystal chemistries. In recent years, however, investigations using transmission electron microscopy and powder x-ray and neutron diffraction methods have provided important new insights into the structures and properties of these materials. The crystal structures for todorokite and birnessite, two of the more common Mn oxide minerals in terrestrial deposits and ocean nodules, were determined by using powder x-ray diffraction data and the Rietveld refinement method. Because of the large tunnels in todorokite and related structures there is considerable interest in the use of these materials and synthetic analogues as catalysts and cation exchange agents. Birnessite-group minerals have layer structures and readily undergo oxidation reduction and cation-exchange reactions and play a major role in controlling groundwater chemistry.

An outbreak of the conjunctival form of infectious bovine rhinotracheitis.

An outbreak of severe conjunctivitis involved approximately 30% of a dairy herd of 118 cattle. Infectious Bovine Rhinotracheitis (IBR) virus was identified by cytopathic effects and fluorescent antibody techniques from conjunctival swabs of affected animals. The disease typically presented as a unilateral ocular disease with systemic signs of pyrexia, inappetance, decreased milk production, and some subsequent abortions.