8,636 research outputs found

    Impoundment Effects on Water Quality as Reflected in Parasitism of Reservoir Basses

    Get PDF
    Our aquatic environments are rapidly becoming useless as natural resources through pollution from various sources. It is therefore necessary for us to further understand the various means which relate to this process. The interrelationships between the physico-chemical and biological water qualities undergo marked changes during the ageing of a reservoir. Eutrophication of these impoundments render them rela-tively useless as natural resources. It thus becomes apparent that we must gain further knowledge of these processes if we are to devise methods for proper reservoir management

    Nonpathogenic Free-Living Amoebae in Arkansas Recreational Waters

    Get PDF
    Selected recreational waters of Arkansas were sampled for pathogenic free-living limax amoebae. Water quality parameters were determined for correlation with amoebic population densities and species diversity. Cultural criteria and animal inoculation revealed no pathogenic strains. The possibility of introduction and/or induction of pathogenic amoebic strains by environmental factors requires further ecological investigations

    A Peculiarly Cerebroid Convex Zygo-Dodecahedron is an Axiomatically Balanced “House of Blues”: The Circle of Fifths to the Circle of Willis to Cadherin Cadenzas

    Get PDF
    A bilaterally symmetrical convex dodecahedron consisting of twelve quadrilateral faces is derived from the icosahedron via a process akin to Fuller’s Jitterbug Transformation. The unusual zygomorphic dodecahedron so obtained is shown to harbor a bilaterally symmetrical jazz/blues harmonic code on its twelve faces that is related to such fundamental music theoretical constructs as the Circle of Fifths and Euler’s tonnetz. Curiously, the patterning within the aforementioned zygo-dodecahedron is discernibly similar to that observed in a ventral view of the human brain. Moreover, this same pattern is arguably evident during development of the embryonic pharynx. A possible role for the featured zygo-dodecahedron in cephalogenesis is considered. Recent studies concerning type II cadherins, an important class of proteins that promote cell adhesion, have generated data that is demonstrated to conform to this zygo-dodecahedral brain model in a substantially congruous manner

    Detecting Stellar Spots by Gravitational Microlensing

    Get PDF
    During microlensing events with a small impact parameter, the amplification of the source flux is sensitive to the surface brightness distribution of the source star. Such events provide a means for studying the surface structure of target stars in the ongoing microlensing surveys, most efficiently for giants in the Galactic bulge. In this work we demonstrate the sensitivity of point-mass microlensing to small spots with radii rs0.2r_s\lesssim0.2 source radii. We compute the amplification deviation from the light curve of a spotless source and explore its dependence on lensing and spot parameters. During source-transit events spots can cause deviations larger than 2%, and thus be in principle detectable. Maximum relative deviation usually occurs when the lens directly crosses the spot. Its numerical value for a dark spot with sufficient contrast is found to be roughly equal to the fractional radius of the spot, i.e., up to 20% in this study. Spots can also be efficiently detected by the changes in sensitive spectral lines during the event. Notably, the presence of a spot can mimic the effect of a low-mass companion of the lens in some events.Comment: 18 pages with 7 Postscript figures, to appear in ApJ, January 2000; discussion expanded, references added, minor revisions in tex

    Population Dynamics and Species Diversity of Ichthyo-Parasitofauna of the Buffalo National River

    Get PDF
    The Buffalo River originates in the Ozark plateau in Newton County, Arkansas. This magnificent Ozarkian wilderness river is about 238 km long and flows north-eastward to its confluence with the White River. The Buffalo River drains 3,465 km2 and has some 30 named tributaries. In its upper reaches, huge multicolored cliffs extend nearly 213 m above the river as it flows through mountainous countryside which reaches an elevation of 732 m. Within its watershed may be found 700 species of plant life, a habitat for 250 species of birds, and a variety of game animals. In its aquatic habitat may be found a variety of game fishes, especially the famous smallmouth bass, Micropterus dolomieui Lacepede. The Buffalo River is known throughout the United States for its outstanding recreational opportunities and unique beauty (State Committee on Stream Preservation 1969)

    Pathogenic Free-Living Amoebae in Arkansas Recreational Waters

    Get PDF
    Selected recreational waters of Arkansas were sampled for pathogenic free-living limax amoebae. Water quality parameters were determined for correlation with amoebic population densities and species diversity. Cultural criteria and animal inoculation revealed no pathogenic strains. The feasibility of introduction and/or induction of pathogenic amoebic strains by environmental factors necessitates further ecological investigaitons

    ROSAT HRI Observations of the Crab Pulsar: An Improved Temperature upper limit for PSR 0531+21

    Get PDF
    ROSAT HRI observations have been used to determine an upper limit of the Crab pulsar surface temperature from the off-pulse count rate. For a neutron star mass of 1.4 \Mo and a radius of 10 km as well as the standard distance and interstellar column density, the redshifted temperature upper limit is\/ Ts1.55×106T_s^\infty \le 1.55\times 10^6 K (3σ)(3\sigma). This is the lowest temperature upper limit obtained for the Crab pulsar so far. Slightly different values for TsT_s^\infty are computed for the various neutron star models available in the literature, reflecting the difference in the equation of state.Comment: 5 pages, uuencoded postscript, to be published in the Proceedings of the NATO Advanced Study Insitute on "Lives of the Neutron Stars", ed. A. Alpar, U. Kiziloglu and J. van Paradijs ( Kluwer, Dordrecht, 1995 )

    Limnological, Ichthyological, and Parasitological Investigations on Arkansas Reservoris in Relation to Water Quality

    Get PDF
    Lake Fort Smith, a 525 acre (212 ha) reservoir, was impounded in 1936 as a water supply for the city of Fort Smith. The reservoir is located on Clear Creek (Frog Bayou), a tributary of the Arkansas River, in the Boston Mountains 28 miles (45 km) northeast of the city of Fort Smith in Crawford County, Arkansas. A map and morphometric characteristics of Lake Fort Smith are given in Fig. 1 and Table I (Hoffman, 1951; Nelson, 1952). In 1956 Lake Shepherd Springs, a 750 acre (304 ha) impoundment, was created one mile upstream of Lake Fort Smith (Rorie, 1961). Both lakes have a shale substrate and are subject to periods of high turbidity. The 2 two lakes have a water shed of 65 square mile area (168 km ) of mountainous oak-hickory forest. Lake Shepherd Springs has not acted as a settling basin for sediments; thus, the upper portion of Lake Fort Smith has numerous shallow areas with a mud bottom supporting various submergent and emergent aquatic plants. The lower portion of the lake has a rocky, shale substrate with only limited emergent vegetation

    Connexins and Diabetes

    Get PDF
    Cell-to-cell interactions via gap junctional communication and connexon hemichannels are involved in the pathogenesis of diabetes. Gap junctions are highly specialized transmembrane structures that are formed by connexon hemichannels, which are further assembled from proteins called “connexins.” In this paper, we discuss current knowledge about connexins in diabetes. We also discuss mechanisms of connexin influence and the role of individual connexins in various tissues and how these are affected in diabetes. Connexins may be a future target by both genetic and pharmacological approaches to develop treatments for the treatment of diabetes and its complications
    corecore