672 research outputs found
Size Estimates of the Extinct Marine Snake Pterosphenus schucherti from Eocene-aged Sediments of Central Georgia
Fossil snakes are most often identified from isolated vertebrae, complicating estimations of total body lengths of extinct taxa. Here we estimate the range of total body length of the late Eocene North American palaeophiid marine snake Pterosphenus schucherti based on 29 recently collected fossil vertebrae from Wilkinson County, Georgia, USA. Previous research suggests that the palaeophiids are most closely related to modern boids. Total body length estimates here are based on family-specific regressions of centrum length versus known total body length in extant members of Boidae, Pythonidae, and Colubridae. The high correlation coefficients for the family specific regressions supports previous studies that used centrum length to estimate total body length in extinct snakes. Here, size estimates for Pterosphenus schucherti ranged from 2.5 to 4.8 m using boids, 3.4 to 13.0 m using pythonids, and 2.8 to 5.3 m using colubrids. This study demonstrates how the lumping of multiple extant clades greatly increases the range of variability for length estimations. For the TL estimates of fossil snakes, it appears that regressions generated from the lowest taxonomic level of the most closely related extant species should be used
Amphiuma (Caudata: Amphiumidae) from the Pleistocene Clark Quarry Local Fauna of Coastal Georgia
Fossil vertebrae of an amphiumid salamander (Amphiuma sp.) are reported from a late Pleistocene (Rancholabrean NALMA) site of coastal Georgia. A suite of vertebral characters that identify the fossils to Amphiuma is given, as well as illustrations of important vertebral characters that distinguish the genus from sirenid salamanders. The presence of Amphiuma in the paleofauna indicates an aquatic habitat was present during the time of deposition
Eocene Terrestrial Mammals From Central Georgia
Descriptions of fossils of Eocene terrestrial mammals from the southeastern United States are rare, and particularly so in the Eocene sediments of Georgia. Here we describe a small collection of fossilized teeth and tooth fragments representing four mammalian taxa. The fossils were recovered by surface collecting overburden sediments and screen washing in situ Clinchfield Formation sediments exposed in an inactive kaolin mine, Hardie Mine, in Wilkinson County, Georgia. The Clinchfield Formation has been described as a Late Eocene coastal unit with abundant gastropods, bivalves, sharks, and rays. This is the first detailed description of terrestrial mammals from this unit. Although limited in diversity, this collection represents the most diverse Eocene-aged mammalian fauna described for the state
A four-season study quantifying the weekly external training loads during different between match microcycle lengths in professional rugby league
This study investigated differences in external training load between microcycle lengths and its variation between microcycles, players, and head coaches. Commonly used external training load variables including total-, high-speed- (5–7 m·s -1), and sprint-distance (> 7 m·s -1) alongside combined high acceleration and deceleration distance (> 2 m·s -2). Which were also expressed relative to time were collected using microtechnology within a repeated measures design from 54 male rugby league players from one Super League team over four seasons. 4337 individual observations across ninety-one separate microcycles and six individual microcycle lengths (5 to 10 day) were included. Linear mixed effects models established the differences in training load between microcycle-length and the variation between-microcycles, players and head coaches. The largest magnitude of difference in training load was seen when comparing 5-day with 9-day (ES = 0.31 to 0.53) and 10-day (ES = 0.19 to 0.66) microcycles. The greatest number of differences between microcycles were observed in high- (ES = 0.3 to 0.53) and sprint-speed (ES = 0.2 to 0.42) variables. Between-microcycle variability ranged between 11% to 35% dependent on training load variable. Training load also varied between players (5–65%) and head coaches (6–20%) with most variability existing within high-speed (19–43%) and sprinting (19–65%). Overall, differences in training load between microcycle lengths exist, likely due to manipulation of session duration. Furthermore, training load varies between microcycle, player and head coach.</p
SIRTF Telescope Instrument Changeout and Cryogen Replenishment (STICCR) Study
The Space Infrared Telescope Facility (SIRTF) is a long-life cryogenically cooled space-based telescope for infrared astronomy from 2 to 700 micrometers. SIRTF is currently under study by NASA-ARC (Reference AP) and planned for launch in approximately the mid 1990s. SIRTF will operate as a multiuser facility, initially carrying three instruments at the focal plane. It will be cooled to below 2 K by superfluid liquid helium to achieve radiometric sensitivity limited only by the statistical fluctuations in the natural infrared background radiation over most of its spectral range. The lifetime of the mission will be limited by the lifetime of the liquid helium supply, and baseline is currently to be 2 years. The telescope changes required to allow in-space replenishment of the 4,000-L superfluid helium tank was investigated. A preliminary design for the space services equipment was also developed. The impacts of basing the equipment and servicing on the space station were investigated. Space replenishment and changeout of instruments required changes to the telescope design. Preliminary concepts are presented
Immunohistochemical Demonstration of IgG in Reed-Sternberg and Other Cells in Hodgkin\u27s Disease
Increased synthesis of IgG in vitro has been demonstrated in spleens from patients with Hodgkin\u27s disease, either with or without invasion of the organ by tumor (1). Interest in this laboratory has centered recently on cytochemical localization of immunoglobulins by means of an immunoglobulin-peroxidase bridge procedure (2) and a satisfactory method has been developed for selectively visualizing immunocytes with this technique. 1 As a means of assessing the basis for increased IgG biosynthesis in spleens of Hodgkin patients, this immunostaining procedure has been applied to localization of IgG-producing cells in specimens with Hodgkin\u27s disease
Effects of environmental exposure on cryogenic thermal insulation materials
Investigation was made to optimize selection of insulation materials for reusable space vehicles which will be repeatedly operated over periods of up to ten years. Results of study are summarized in two reports. Volume I describes tests and significant findings. In Volume II, extensive test data obtained are organized in handbook form
Vitamin E restores impaired acetyicholine-mediated vasodilatation secondary to environmental tobacco smoke
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