Southern Illinois University Carbondale

About: Southern Illinois University Carbondale is a education organization based out in Carbondale, Illinois, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 13570 authors who have published 24819 publications receiving 667385 citations. The organization is also known as: SIU Carbondale & SIUC.

Field inversion and point halving revisited

Abstract: We present a careful analysis of elliptic curve point multiplication methods that use the point halving technique of Knudsen and Schroeppel and compare these methods to traditional algorithms that use point doubling. The performance advantage of halving methods is clearest in the case of point multiplication kP, where P is not known in advance and smaller field inversion to multiplication ratios generally favor halving. Although halving essentially operates on affine coordinate representations, we adapt an algorithm of Knuth to allow efficient use of projective coordinates with halving-based windowing methods for point multiplication.

Linkage of manchette microtubules to the nuclear envelope and observations of the role of the manchette in nuclear shaping during spermiogenesis in rodents.

Abstract: Structural features of the mouse and rat manchette and the role of the manchette in shaping the spermatid nucleus were investigated. Rod-like elements about 10 nm in diameter and 40-70 nm in length were seen linking the innermost microtubules of the manchette and the outer leaflet of the nuclear envelope in step 8 through step 11 rat and mouse spermatids that either had been routinely fixed for electron microscopy or had been isolated and detergent extracted. Rod-like linkers were also seen joining the nuclear ring to the plasma membrane and nuclear envelope. These linkers may ensure that under normal conditions the manchette remains in a defined position relative to these membranous components. A variety of compounds (taxol, cytoxan, and 5-fluorouracil) were found to perturb the manchette and to affect nuclear shaping. In addition, sys and azh mutant mice were used to determine the consequences of defective manchette formation. These genetic conditions and chemical treatments either produced manchettes that were not in their normal position (azh, sys, and taxol) and/or caused the manchette to appear abnormal (azh, sys, cytoxan, 5-fluorouracil, and taxol), and all resulted in a deformation of the step 9-11 spermatid nucleus. In all instances where the manchette was present, either in normal or ectopic locations, the sectioned nuclear envelope was parallel to the long axis of the microtubules of the manchette. In general, areas of the nuclear envelope where the manchette was not present, or where it was expected to be present but was not, were rounded (normal animals, sys, cytoxan). In addition, there are indications using certain compounds (cytoxan and 5-fluorouracil) as well as in the azh and sys mouse that the manchette may exert pressure to deform the nucleus. It is suggested that the rod-like linkages of the manchette ensure that the nuclear envelope remains at a constant distance from the manchette microtubules and that this is a major factor acting to impart nuclear shape changes on a region of the head caudal to the acrosome during the early elongation phase of spermiogenesis. The manchette microtubules, which are also known to be linked together, may act as a scaffold to deform this part of the nucleus from its spherical shape, perhaps in concert with forces initiated by other structural elements. Evidence from sys animals indicates that structural elements, such as the acrosomal complex over the anterior head (acrosome-actin-nuclear envelope), may affect nuclear shaping over the acrosome-covered portion of the spermatid head.(ABSTRACT TRUNCATED AT 400 WORDS)

Perfluorooctanesulfonate and related fluorinated hydrocarbons in mink and river otters from the United States.

Abstract: Mink and otters are good integrators of their aquatic environments and useful sentinel species for determining exposure to environmental contaminants. In this study, perfluorooctanesulfonate (PFOS; C8F17SO3-), perfluorooctanesulfonamide (FOSA; C8F17SO2NH2), perfluorohexanesulfonate (PFHxS; C6F13SO3-), and perfluorooctanoate (PFOA; C7F15CO2-) were measured in livers of mink and river otters collected from various locations in the United States. PFOS was found in all mink livers analyzed. Frequencies of occurrence of FOSA, PFHxS, and PFOA were less. The greatest concentration of PFOS measured in liver of mink was 5140 ng/g, wet weight. Maximum concentrations of FOSA, PFHxS, and PFOA in mink livers were 590, 39, and 27 ng/g, wet weight, respectively. There were no significant positive relationships between concentrations of PFOS and PFHxS or PFOA in mink livers. Concentrations of PFOS were positively correlated with those of FOSA in mink livers from Illinois. There was no significant correlation between conc...

Phylogeny and diversification of bryophytes.

Abstract: The bryophytes comprise three phyla of embryophytes that are well established to occupy the first nodes among extant lineages in the land-plant tree of life. The three bryophyte groups (hornworts, liverworts, mosses) may not form a monophyletic clade, but they share life history features including dominant free-living gametophytes and matrotrophic monosporangiate sporophytes. Because of their unique vegetative and reproductive innovations and their critical position in embryophyte phylogeny, studies of bryophytes are crucial to understanding the evolution of land plant morphology and genomes. This review focuses on phylogenetic relationships within each of the three divisions of bryophytes and relates morphological diversity to new insights about those relationships. Most previous work has been on the mosses, but progress on understanding the phylogeny of hornworts and liverworts is advancing at a rapid pace. Multilocus multigenome studies have been successful at resolving deep relationships within the mosses and liverworts, whereas single-gene analyses have advanced understanding of hornwort evolution.