660 research outputs found

    Freeze branding cattle (1993)

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    Freeze branding as a method of livestock identification has been received with enthusiasm. When super-cold or chilled branding irons are applied to the hide of the animal, the pigment-producing cells are destroyed or altered. When the hair grows back, it is white. The method is not foolproof, and those using it should be aware that the results may be variable

    Accessibility of the resources of near Earth space using multi-impulse transfers

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    Most future concepts for exploration and exploitation of space require a large initial mass in low Earth orbit. Delivering this mass requires overcoming Earth's natural gravity well, which imposes a distinct obstacle to space-faring. An alternative for future space progress is to search for resources in-situ among the near Earth asteroid population. This paper examines the scenario of future utilization of asteroid resources. The near Earth asteroid resources that could be transferred to a bound Earth orbit are determined by integrating the probability of finding asteroids inside the Keplerian orbital element space of the set of transfers with an specific energy smaller than a given threshold. Transfers are defined by a series of impulsive maneuvers and computed using the patched-conic approximation. The results show that even moderately low energy transfers enable access to a large mass of resources

    Ternatin and improved synthetic variants kill cancer cells by targeting the elongation factor-1A ternary complex.

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    Cyclic peptide natural products have evolved to exploit diverse protein targets, many of which control essential cellular processes. Inspired by a series of cyclic peptides with partially elucidated structures, we designed synthetic variants of ternatin, a cytotoxic and anti-adipogenic natural product whose molecular mode of action was unknown. The new ternatin variants are cytotoxic toward cancer cells, with up to 500-fold greater potency than ternatin itself. Using a ternatin photo-affinity probe, we identify the translation elongation factor-1A ternary complex (eEF1A·GTP·aminoacyl-tRNA) as a specific target and demonstrate competitive binding by the unrelated natural products, didemnin and cytotrienin. Mutations in domain III of eEF1A prevent ternatin binding and confer resistance to its cytotoxic effects, implicating the adjacent hydrophobic surface as a functional hot spot for eEF1A modulation. We conclude that the eukaryotic elongation factor-1A and its ternary complex with GTP and aminoacyl-tRNA are common targets for the evolution of cytotoxic natural products

    Duration of Posttraumatic Amnesia Predicts Neuropsychological and Global Outcome in Complicated Mild Traumatic Brain Injury.

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    OBJECTIVES: Examine the effects of posttraumatic amnesia (PTA) duration on neuropsychological and global recovery from 1 to 6 months after complicated mild traumatic brain injury (cmTBI). PARTICIPANTS: A total of 330 persons with cmTBI defined as Glasgow Coma Scale score of 13 to 15 in emergency department, with well-defined abnormalities on neuroimaging. METHODS: Enrollment within 24 hours of injury with follow-up at 1, 3, and 6 months. MEASURES: Glasgow Outcome Scale-Extended, California Verbal Learning Test II, and Controlled Oral Word Association Test. Duration of PTA was retrospectively measured with structured interview at 30 days postinjury. RESULTS: Despite all having a Glasgow Coma Scale Score of 13 to 15, a quarter of the sample had a PTA duration of greater than 7 days; half had PTA duration of 1 of 7 days. Both cognitive performance and Extended Glasgow Outcome Scale outcomes were strongly associated with time since injury and PTA duration, with those with PTA duration of greater than 1 week showing residual moderate disability at 6-month assessment. CONCLUSIONS: Findings reinforce importance of careful measurement of duration of PTA to refine outcome prediction and allocation of resources to those with cmTBI. Future research would benefit from standardization in computed tomographic criteria and use of severity indices beyond Glasgow Coma Scale to characterize cmTBI

    High-temperature phase transitions in dense germanium.

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    Through a series of high-pressure x-ray diffraction experiments combined with in situ laser heating, we explore the pressure-temperature phase diagram of germanium (Ge) at pressures up to 110 GPa and temperatures exceeding 3000 K. In the pressure range of 64-90 GPa, we observe orthorhombic Ge-IV transforming above 1500 K to a previously unobserved high-temperature phase, which we denote as Ge-VIII. This high-temperature phase is characterized by a tetragonal crystal structure, space group I4/mmm. Density functional theory simulations confirm that Ge-IV becomes unstable at high temperatures and that Ge-VIII is highly competitive and dynamically stable at these conditions. The existence of Ge-VIII has profound implications for the pressure-temperature phase diagram, with melting conditions increasing to much higher temperatures than previous extrapolations would imply

    Cultural Resources Investigations Along Whiteoak Bayou, Harris County, Texas

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    In 1986, cultural resources investigations were carried out to prepare a synthesis of the archeology of the Whiteoak Bayou area in western Harris County, Texas, and to conduct subsurface testing at prehistoric sites that may be affected by the U.S. Army Corps of Engineers Upper Whiteoak Bayou Flood Damage Reduction Project. The tasks undertaken during these investigations are: (1) background research into the environment and archeology of the area; (2) historic/archival research and reconnaissance survey to summarize the historical development of Whiteoak Bayou and to identify any important sites in the project area; (3) intensive survey of Vogel Creek, a tributary to Whiteoak Bayou, to assess the potential for intact cultural remains; (4) National Register testing and assessment of nine aboriginal sites; (5) geoarcheological investigations to establish the geological context of the archeological remains, to identify the depositional environments represented, and to establish an alluvial sequence for the project area; and (6) analysis of a large collection of artifacts from 46 Whiteoak Bayou sites made prior to 1986 by members of the Houston Archeological Society, as well as the materials recovered during 1986. The nine archeological sites tesLed during this project are 41HR241, 4lHR259, 41HR273, 41HR278, 41HR279, 41HR283, 41HR290, 41HR298, and 41HR541. The testing showed that only three -- 41HR259, 41HR273, and 41HR541 -- have substantial, intact cultural deposits. Two of these -- 41HR273 and 41HR541 -- are judged to be eligible for listing on the National Register of Historic Places and for designation as State Archeological Landmarks. One site, 4lHR259, is currently listed on the National Register, although the remaining part of this site is judged to have a limited potential to yield additi0nal information. The other seven sites are judged to be ineligible for listing
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