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Sample records for kincaid derek walker

  1. Derek Bendall (1930-2014).

    PubMed

    Howe, Christopher J; Rich, Peter R; Ubbink, Marcellus

    2015-06-01

    Derek Bendall carried out pioneering work on photosynthetic electron transport, particularly on protein-protein interactions, cytochromes, and cyclic electron transport, as well as on other topics including the biochemistry of tea. He was a keen musician and a gifted gardener, a devoted family man, and a delightful colleague and friend. The bioenergetics community, especially those working on photosynthesis, will miss him sorely.

  2. Voices Inside Schools: Getting to Know Derek

    ERIC Educational Resources Information Center

    Paley, Vivian Gussin

    2011-01-01

    In this "Voices Inside Schools" essay, Vivian Gussin Paley brings us into Derek's kindergarten classroom using her characteristic style of listening and recounting from the child's perspective. With delicacy and insight, she reveals the small but significant moments that occur alongside the planned curriculum to illustrate how children author…

  3. Geophysicists: Derek York (1937-2007)

    NASA Astrophysics Data System (ADS)

    Renne, Paul R.

    2008-02-01

    Derek York, a pioneer of modern geochronology, died at age 70 on 9 August 2007 after a battle with prostate cancer. York was a professor emeritus of physics at the University of Toronto, Canada, where he spent his entire career after receiving his Ph.D. from University College, Oxford, U.K., in 1960. Born in Yorkshire, England, York's undergraduate studies were also at Oxford.

  4. Agile Walker.

    PubMed

    Katz, Reuven

    2015-01-01

    The goal of the Agile Walker is to improve the outdoor mobility of healthy elderly people with some mobility limitations. It is a newly developed, all-terrain walker, equipped with an electric drive system and speed control that can assists elderly people to walk outdoors or to hike. The walker has a unique product design with an attractive look that will appeal to "active-agers" population. This paper describes product design requirements and the development process of the Agile Walker, its features and some preliminary testing results.

  5. Stratigraphy and sedimentology of Kincaid Formation, Midway Group (Paleocene), Upper Rio Grande Embayment, Texas

    SciTech Connect

    Roy, E.C. Jr.

    1984-09-01

    Sedimentary rocks of the Kincaid Formation crop out along the northern and western edges of the Rio Grande Embayment. Siltstones are exposed at the type locality of the Kincaid Formation along the Frio River in Uvalde County, Texas. On the east and south, the Kincaid Formation changes facies to richly fossiliferous carbonate rocks; however, basinward, it grades into a shale facies that contains interbedded units of fine-grained sandstone. At the type locality of the Kincaid Formation, approximately 30 ft (9 m) of massive siltstone grades upward into a very silty limestone unit. Bedding is poorly defined throughout the section, largely the result of intensive bioturbation. The grain size of the siltstone increases upward, ranging from medium to coarse. Clay content in the siltstone decreases upward as the amount of calcareous material increases. The upper 4-6 ft (1.2-1.8 m) may actually be considered a silty limestone. A dramatic facies change is present along the outcrop both east and south of the type section. To the east, the Kincaid Formation is composed of glauconitic and highly fossiliferous limestone. The siltstone present at the type locality thins eastward and is absent less than 20 mi (32 km) away. Eighty miles (130 km) to the south, along the Rio Grande River, approximately 45 ft (14 m) of limestone and shale comprise the Kincaid Formation. These early Paleocene sediments are interpreted to be shallow marine in origin. The siltstone represents a shallow sublittoral shoreface environment whereas the limestones on the east and south were deposited in shallow nearshore environments beyond the reach of clastic deposition.

  6. Comparison of Recreational Reading Books Levels Using the Fry Readability Graph and the Flesch-Kincaid Grade Level.

    ERIC Educational Resources Information Center

    Hoke, Brenda Lynn

    This study was done to see if readability levels printed on recreational reading books were as accurate as when the Fry formula and the Flesch-Kincaid Grade Level were applied to them. Three descriptive passages from each of 60 recreational reading books were analyzed using the Fry formula and the Flesch-Kincaid formula. The data was compared to…

  7. Using a walker

    MedlinePlus

    ... many types of walkers. Some walkers have no wheels, 2 wheels, or 4 wheels. You can also get a walker with brakes, ... If your walker has wheels, you will push it forward to move forward. If you walker does not have wheels, then you will need to ...

  8. Compliant walker

    NASA Technical Reports Server (NTRS)

    Kerley, James J. (Inventor); Eklund, Wayne D. (Inventor); Crane, J. Allen (Inventor)

    1992-01-01

    A compliant walker is provided for humans having limited use of their legs and lower back. It includes an upright wheel frame which at least partially surrounds an upright user wearing a partial body harness. It is attached to the frame by means of cable compliant apparatus consisting of sets of cable segments and angle bracket members connected between opposite side members of the frame and adjacent side portions of the harness. Novelty is believed to exist in the combination of a wheeled frame including a side support structure, a body harness, and compliance means connecting the body harness to the side support structure for flexibility holding and supporting a person in a substantially upright position when the user sags in the frame when taking weight off the lower extremities.

  9. Walker's Eleodes (Coleoptera: Tenebrionidae).

    PubMed

    Thomas, Donald B; Smith, Aaron D; Triplehorn, Charles A; Aalbu, Rolf A

    2014-01-01

    The type specimens of five species of Eleodes described by Francis Walker from British Columbia, Canada, were studied in order to establish their true identity. The synonymy of Eleodes convexicollis Walker and E. conjunctus Walker with E. obscurus (Say); that of Eleodes latiusculus Walker with E. humeralis LeConte;  and that of Eleodes binotatus Walker with  Eleodes hispilabris (Say) is confirmed. Eleodes subtuberculatus Walker = Eleodes parvulus Blaisdell, new synonymy, and not a synonym of E. granulatus LeConte. Only in the latter case is a Walker name senior to the name currently in use.  PMID:25081472

  10. Iterative ensemble Kalman filter for atmospheric dispersion in nuclear accidents: An application to Kincaid tracer experiment.

    PubMed

    Zhang, X L; Su, G F; Chen, J G; Raskob, W; Yuan, H Y; Huang, Q Y

    2015-10-30

    Information about atmospheric dispersion of radionuclides is vitally important for planning effective countermeasures during nuclear accidents. Results of dispersion models have high spatial and temporal resolutions, but they are not accurate enough due to the uncertain source term and the errors in meteorological data. Environmental measurements are more reliable, but they are scarce and unable to give forecasts. In this study, our newly proposed iterative ensemble Kalman filter (EnKF) data assimilation scheme is used to combine model results and environmental measurements. The system is thoroughly validated against the observations in the Kincaid tracer experiment. The initial first-guess emissions are assumed to be six magnitudes underestimated. The iterative EnKF system rapidly corrects the errors in the emission rate and wind data, thereby significantly improving the model results (>80% reduction of the normalized mean square error, r=0.71). Sensitivity tests are conducted to investigate the influence of meteorological parameters. The results indicate that the system is sensitive to boundary layer height. When the heights from the numerical weather prediction model are used, only 62.5% of reconstructed emission rates are within a factor two of the actual emissions. This increases to 87.5% when the heights derived from the on-site observations are used.

  11. Becoming through Revolutionary Pedagogy: An Interview with Curry Malott and Derek R. Ford

    ERIC Educational Resources Information Center

    Wubbena, Zane C.

    2016-01-01

    In this interview, Curry Malott and Derek R. Ford discuss their new book, "Marx, Capital, and Education: Towards a Critical Pedagogy of Becoming." The interview begins with a general inquiry into their intellectual backgrounds as scholar-activists and, importantly, comrades. The authors then discuss the process of collaborating together…

  12. Voluntary Euthanasia and the Right to Die: A Dialogue with Derek Humphry.

    ERIC Educational Resources Information Center

    Sinnett, E. Robert; And Others

    1989-01-01

    Presents interview with Derek Humphry, founder of the Hemlock Society (an international right-to-die organization), who shares his personal experiences, as well as his efforts to educate the public and stimulate legal reform. Notes Humphry has dedicated more than a decade to this highly charged universal problem. (Author/ABL)

  13. Microscopic Tribotactic Walkers

    NASA Astrophysics Data System (ADS)

    Steimel, Joshua; Aragones, Juan; Alexander-Katz, Alfredo

    2014-03-01

    The translational motion of a rotating object near a surface is strongly dependent on the friction between the object and the surface. The process of friction is inherently directional and the friction coefficient can be anisotropic even in the absence of a net friction coefficient gradient. This is macroscopically observed in the ordering motif of some animal hair or scales and a microscopic analog can be imagined where the friction coefficient is determined by the strength and density of reversible bonds between a rotating object and the substrate. For high friction coefficients most of the rotational motion is converted into translational motion; conversely for low friction coefficients the object primarily rotates in place. We exploited this property to design and test a new class of motile system that displays tribotaxis, which is the process by which an object detects differences in the local friction coefficient and moves accordingly either to regions of higher or lower friction. These synthetic tribotactic microscopic walkers, composed of a pair of functionalized superparamagnetic beads, detect gradients in the spatial friction coefficient and migrate towards high friction areas when actuated in a random fashion. The effective friction between the walkers and the substrate is controlled by the local density of active receptors in the substrate. The tribotactic walkers also displayed trapping in high friction areas where the density of free receptors is higher.

  14. Joseph (Joe) A. Walker

    NASA Technical Reports Server (NTRS)

    1956-01-01

    In March 1945 Joseph A. Walker joined the National Advisory Committee for Aeronautics' Aircraft Engine Research Laboratory, Cleveland, Ohio, (later NASA's Lewis Research Center, now the Glenn Research Center) as a physicist. He transferred to the NACA High-Speed Flight Research Station, Edwards, California in 1951, as a research pilot. For the next fifteen years Walker served as a pilot at the Edwards flight research facility (today known as NASA's Dryden Flight Research Center) on such projects as the Bell X-1#2 (2 flights, first on August 27, 1951), Bell X-1A (1 flight on July 20, 1955), X-1E (21 flights, first on December 12, 1955), Douglas D-558-I #3 Skystreak (14 flights, first on June 29, 1951), Douglas D-558-II #2 Skyrocket (3 flights, first on April 29, 1955), Douglas D-558-II #3 Skyrocket (2 flights, first on May 7, 1954). On the Douglas X-3, Joe was project pilot and made all 20 flights, the first on August 1, 1954. Joe considered this aircraft the 'worst' plane he ever flew. He flew the Northrup X-4 (2 flights, first on October 18, 1951), Bell X-5 (78 flights, first on January 9, 1952). He also flew programs involving the F-100, F-101, F-102, F-104 and the B-47. Walker made the first NASA flight on the North American X-15 on March 25, 1960. His 25th and final X-15 flight on August 22, 1963, reached 354,200 feet, an unofficial record altitude of almost 67 miles. On October 30, 1964, Walker took the first Bell Lunar Landing Research Vehicle (LLRV) on its maiden flight, reaching a peak altitude of 10 feet and a free flight time of just under one minute. Two LLRV's and three Lunar Landing Training Vehicles developed from them were used to develop piloting and operational techniques for lunar landings. In November, he left the program after 35 flights on the first LLRV. Walker flew chase flights as well as research flights. On June 8, 1966 he was flying chase in NASA's F-104N for the Air Force's experimental bomber, North American XB-70A, when he was fatally

  15. Synthetic molecular walkers.

    PubMed

    Leigh, David A; Lewandowska, Urszula; Lewandowski, Bartosz; Wilson, Miriam R

    2014-01-01

    In biological systems, molecular motors have been developed to harness Brownian motion and perform specific tasks. Among the cytoskeletal motor proteins, kinesins ensure directional transport of cargoes to the periphery of the cell by taking discrete steps along microtubular tracks. In the past decade there has been an increasing interest in the development of molecules that mimic aspects of the dynamics of biological systems and can became a starting point for the creation of artificial transport systems.To date, both DNA-based and small-molecule walkers have been developed, each taking advantage of the different chemistries available to them. DNA strollers exploit orthogonal base pairing and utilize strand-displacement reactions to control the relative association of the component parts. Small-molecule walkers take advantage of the reversibility of weak noncovalent interactions as well as the robustness of dynamic covalent bonds in order to transport molecular fragments along surfaces and molecular tracks using both diffusional processes and ratchet mechanisms. Here we review both types of synthetic systems, including their designs, dynamics, and how they are being used to perform functions by controlled mechanical motion at the molecular level.

  16. Simple autonomous Mars walker

    NASA Technical Reports Server (NTRS)

    Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.

    1989-01-01

    Under a contract with NASA's Jet Propulsion Laboratory, Martin Marietta has developed several alternative rover concepts for unmanned exploration of the planet Mars. One of those concepts, the 'Walking Beam', is the subject of this paper. This concept was developed with the goal of achieving many of the capabilities of more sophisticated articulated-leg walkers with a much simpler, more robust, less computationally demanding and more power efficient design. It consists of two large-base tripods nested one within the other which alternately translate with respect to each other along a 5-meter beam to propel the vehicle. The semiautonomous navigation system relies on terrain geometry sensors and tacticle feedback from each foot to autonomously select a path which avoids hazards along a route designated from earth. Both mobility and navigation features of this concept are discussed including a top-level description of the vehicle's physical characteristics, deployment strategy, mobility elements, sensor suite, theory of operation, navigation and control processes, and estimated performance.

  17. The Albany Medical College Ventilator Walker.

    PubMed

    Smith, T; Forrest, G; Evans, G; Johnson, R K; Chandler, N

    1996-12-01

    This report describes the design and use of a wheeled walker that can accommodate a ventilator and oxygen tanks. It is constructed of aluminum tubing. The front of the walker has receptacles to support a Mark 7 Bird Ventilator and oxygen tanks. The back end of the walker has a bench seat that is lifted to allow entry into the walker. The seat provides rigidity and stability to the frame of the walker. The walker has been used in the Medical Intensive Care Unit of the Albany Medical Center to facilitate early ambulation of patients who are ventilator dependent or who require a portable source of oxygen to begin ambulation training.

  18. [Webometrics – on the occasion of the awarding of the Derek John de Solla Price Medal, 2015].

    PubMed

    Schubert, András

    2015-09-01

    The most significant recognition in scientometrics, the Derek John de Solla Price Medal was awarded in 2015 to Mike Thelwall. Thelwall is a dominant personality in webometrics studying the internet presence of scientific research with quantitative methods. In this paper the emergence, standing and directions of webometrics are briefly reviewed.

  19. Intelligently Controllable Walker with Magnetorheological Fluid Brake

    NASA Astrophysics Data System (ADS)

    Kikuchi, Takehito; Tanida, Sosuke; Tanaka, Toshimasa; Kobayashi, Keigo; Mitobe, Kazuhisa

    Caster walkers are supporting frames with casters and wheels. These tools are regularly utilized as life support tools or walking rehabilitation tools in hospitals, nursing homes and individual residences. Users of the walkers can easily move it thanks to its wheels and casters. However falling accidents often happen when it moves without users. The falling accident is very serious problem and one of leading causes of secondary injuries. In the other case, it is hard to move to desired directions if users have imbalance in their motor functions or sensory functions, e.g., hemiplegic patients. To improve safeness and operability of the walkers, we installed compact MR fluid brakes on the wheels and controlled walking speed and direction of the walker. We named this intelligently controllable walker, “i-Walker” and discussed on the control methods and experimental results in this paper. Preliminary trials for direction control of the first-generation of the i-Walker (i-Walker1) are presented. On the basis of the results, we improved the control method and hardware of the i-Walker1, and developed the second-generation (i-Walker2). System description and experimental results of the i-Walker2 are also described. The i-Walker2 has better operability and lower energy consumption than that of the i-Walker1. The line-tracing controller of the i-Walker2 well controls human motions during walking experiments on the target straight line.

  20. 4. CONTEXTUAL VIEW OF WALKER BRIDGE FROM IRRIGATED PASTURE BETWEEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. CONTEXTUAL VIEW OF WALKER BRIDGE FROM IRRIGATED PASTURE BETWEEN THE KLAMATH RIVER AND WALKER ROAD; FACING WEST. - Walker Bridge, Spanning Klamath River and connecting Highway 96 and Walker Road, Klamath River, Siskiyou County, CA

  1. Genetics Home Reference: Walker-Warburg syndrome

    MedlinePlus

    ... a group of genetic conditions known as congenital muscular dystrophies, which cause muscle weakness and wasting (atrophy) beginning ... or management of Walker-Warburg syndrome: GeneReview: Congenital Muscular Dystrophy Overview Genetic Testing Registry: Walker-Warburg syndrome These ...

  2. Genetics Home Reference: Dandy-Walker malformation

    MedlinePlus

    ... All Close All Description Dandy-Walker malformation affects brain development, primarily development of the cerebellum , which is the ... Walker malformation , signs and symptoms caused by abnormal brain development are present at birth or develop within the ...

  3. Abstract models of molecular walkers

    NASA Astrophysics Data System (ADS)

    Semenov, Oleg

    Recent advances in single-molecule chemistry have led to designs for artificial multi-pedal walkers that follow tracks of chemicals. The walkers, called molecular spiders, consist of a rigid chemically inert body and several flexible enzymatic legs. The legs can reversibly bind to chemical substrates on a surface, and through their enzymatic action convert them to products. We study abstract models of molecular spiders to evaluate how efficiently they can perform two tasks: molecular transport of cargo over tracks and search for targets on finite surfaces. For the single-spider model our simulations show a transient behavior wherein certain spiders move superdiffusively over significant distances and times. This gives the spiders potential as a faster-than-diffusion transport mechanism. However, analysis shows that single-spider motion eventually decays into an ordinary diffusive motion, owing to the ever increasing size of the region of products. Inspired by cooperative behavior of natural molecular walkers, we propose a symmetric exclusion process (SEP) model for multiple walkers interacting as they move over a one-dimensional lattice. We show that when walkers are sequentially released from the origin, the collective effect is to prevent the leading walkers from moving too far backwards. Hence, there is an effective outward pressure on the leading walkers that keeps them moving superdiffusively for longer times. Despite this improvement the leading spider eventually slows down and moves diffusively, similarly to a single spider. The slowdown happens because all spiders behind the leading spiders never encounter substrates, and thus they are never biased. They cannot keep up with leading spiders, and cannot put enough pressure on them. Next, we investigate search properties of a single and multiple spiders moving over one- and two-dimensional surfaces with various absorbing and reflecting boundaries. For the single-spider model we evaluate by how much the

  4. Walker Branch Watershed Ecosystems Data

    DOE Data Explorer

    Walker Branch Watershed is located on the U. S. Department of Energy's Oak Ridge Reservation near Oak Ridge, in Anderson County, Tennessee. The Walker Branch Watershed Project began in 1967 under sponsorship of the U. S. Atomic Energy Commission (now the U. S. Department of Energy). Initially, the project centered primarily on the geologic and hydrologic processes that control the amounts and chemistry of water moving through the watershed. Past projects have included: • U. S. Department of Energy funded studies of watershed hydrology and forest nutrient dynamics • National Oceanic and Atmospheric Administration funded studies of forest micrometeorology • Studies of atmospheric deposition under the National Atmospheric Deposition Program • The International Biological Program Eastern Deciduous Forest Biome Project • National Science Foundation sponsored studies of trace element cycling and stream nutrient spiraling • Electric Power Research Institute funded studies of the effects of acidic deposition on canopy processes and soil chemistry. These projects have all contributed to a more complete understanding of how forest watersheds function and have provided insights into the solution of energy-related problems associated with air pollution, contaminant transport, and forest nutrient dynamics. This is one of a few sites in the world characterized by long-term, intensive environmental studies. The Walker Branch Watershed website at http://walkerbranch.ornl.gov/ provides maps, photographs, and data on climate, precipitation, atmospheric deposition, stream discharge and runoff, stream chemistry, and vegetation. [Taken from http://walkerbranch.ornl.gov/ABOUTAAA.HTM

  5. The scholar as craftsman: Derek de Solla Price and the reconstruction of a medieval instrument.

    PubMed

    Falk, Seb

    2014-06-20

    The Royal Society Conversaziones were biannual social evenings at which distinguished guests could learn about the latest scientific developments. The Conversazione in May 1952 featured an object that came to be called King Arthur's Table. It was a planetary equatorium, made in Cambridge's Cavendish Laboratory at the behest of Sir Lawrence Bragg. Conceived by the historian of science Derek de Solla Price as a huge, tangible realization of Chaucerian astronomy, it was displayed at the new Whipple Museum of the History of Science, discarded, stored incognito, catalogued with that whimsical name, and finally re-identified in 2012. This article examines the biography of that object and, through it, the early, inchoate years of the discipline of history of science in Cambridge. The process of disciplinary establishment involved a range of actors beyond well-known figures such as Herbert Butterfield and Joseph Needham; the roles of Price and Bragg are highlighted here. Study of these individuals, and of the collaboration that brought about the reconstruction, reveals much about the establishment of a discipline, as well as changing scholarly and curatorial attitudes towards replicas.

  6. The scholar as craftsman: Derek de Solla Price and the reconstruction of a medieval instrument

    PubMed Central

    Falk, Seb

    2014-01-01

    The Royal Society Conversaziones were biannual social evenings at which distinguished guests could learn about the latest scientific developments. The Conversazione in May 1952 featured an object that came to be called King Arthur's Table. It was a planetary equatorium, made in Cambridge's Cavendish Laboratory at the behest of Sir Lawrence Bragg. Conceived by the historian of science Derek de Solla Price as a huge, tangible realization of Chaucerian astronomy, it was displayed at the new Whipple Museum of the History of Science, discarded, stored incognito, catalogued with that whimsical name, and finally re-identified in 2012. This article examines the biography of that object and, through it, the early, inchoate years of the discipline of history of science in Cambridge. The process of disciplinary establishment involved a range of actors beyond well-known figures such as Herbert Butterfield and Joseph Needham; the roles of Price and Bragg are highlighted here. Study of these individuals, and of the collaboration that brought about the reconstruction, reveals much about the establishment of a discipline, as well as changing scholarly and curatorial attitudes towards replicas. PMID:24921105

  7. Recent progress on DNA based walkers.

    PubMed

    Pan, Jing; Li, Feiran; Cha, Tae-Gon; Chen, Haorong; Choi, Jong Hyun

    2015-08-01

    DNA based synthetic molecular walkers are reminiscent of biological protein motors. They are powered by hybridization with fuel strands, environment induced conformational transitions, and covalent chemistry of oligonucleotides. Recent developments in experimental techniques enable direct observation of individual walkers with high temporal and spatial resolution. The functionalities of state-of-the-art DNA walker systems can thus be analyzed for various applications. Herein we review recent progress on DNA walker principles and characterization methods, and evaluate various aspects of their functions for future applications.

  8. Infant walker use, injuries, and motor development.

    PubMed Central

    Thein, M. M.; Lee, J.; Tay, V.; Ling, S. L.

    1997-01-01

    OBJECTIVES: To study the impact of infant walker use on motor development and injuries. POPULATION: One hundred and eighty five parents or primary care givers who attended a Singapore government polyclinic from September 1993 to February 1994, with their infants between 7 to 10 months, for a developmental assessment session. SETTING: A government polyclinic in Singapore. METHODS: The parent or primary care giver answered questions pertaining to infant walker use and injuries attributed to its use. Each infant was then given the Singapore modified version of the Denver Developmental Screening Test (DDST-S), along with a full clinical examination; both testers were blinded to walker use. RESULTS: One hundred and sixty seven (90%) of 185 infants used walkers regularly, and 21 (12.5%) of the users had one or more injuries. Most injuries were minor, such as bruises and swellings on the head, forehead, face, and cheeks. None of the children who did not use walkers showed any abnormal DDST-S results whereas 18 (10.8%) of the 167 walker users had either abnormal or questionable DDST-S results. CONCLUSIONS: 12.5% of walker users had one or more injuries and walker use may also delay the child's motor development. These findings will help the physician or nurse in primary care settings to advise parents about the potential hazards of walker use. PMID:9113852

  9. George Walker, 1926-2005

    NASA Astrophysics Data System (ADS)

    Self, Stephen

    2006-08-01

    George Patrick Leonard Walker, an outstanding and multi-faceted geologist andone of the most influential volcanologists in the world, died on 17 January 2005, at the age of 78. He was born in London on 2 March1926 and grew up mainly in Northern Ireland. He read geology for B.Sc. honors and M.Sc. degrees at Queens University in Belfast,Northern Ireland, and completed his training with a Ph.D. in mineralogy from Leeds Universityin England, which he received in 1956. By then, he had already been appointed, in 1954, to a lectureship at Imperial College London.

  10. 8. OBLIQUE VIEW OF WALKER BRIDGE FROM PASTURE SOUTH OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. OBLIQUE VIEW OF WALKER BRIDGE FROM PASTURE SOUTH OF THE KLAMATH RIVER; FACING NORTHEAST. - Walker Bridge, Spanning Klamath River and connecting Highway 96 and Walker Road, Klamath River, Siskiyou County, CA

  11. Averaging Robertson-Walker cosmologies

    NASA Astrophysics Data System (ADS)

    Brown, Iain A.; Robbers, Georg; Behrend, Juliane

    2009-04-01

    The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy, strictly speaking any cosmological model should be recovered from such a procedure. We apply the scalar spatial averaging formalism for the first time to linear Robertson-Walker universes containing matter, radiation and dark energy. The formalism employed is general and incorporates systems of multiple fluids with ease, allowing us to consider quantitatively the universe from deep radiation domination up to the present day in a natural, unified manner. Employing modified Boltzmann codes we evaluate numerically the discrepancies between the assumed and the averaged behaviour arising from the quadratic terms, finding the largest deviations for an Einstein-de Sitter universe, increasing rapidly with Hubble rate to a 0.01% effect for h = 0.701. For the ΛCDM concordance model, the backreaction is of the order of Ωeff0 approx 4 × 10-6, with those for dark energy models being within a factor of two or three. The impacts at recombination are of the order of 10-8 and those in deep radiation domination asymptote to a constant value. While the effective equations of state of the backreactions in Einstein-de Sitter, concordance and quintessence models are generally dust-like, a backreaction with an equation of state weff < -1/3 can be found for strongly phantom models.

  12. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker....

  13. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker....

  14. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker....

  15. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker....

  16. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker....

  17. In silico tools for sharing data and knowledge on toxicity and metabolism: derek for windows, meteor, and vitic.

    PubMed

    Marchant, Carol A; Briggs, Katharine A; Long, Anthony

    2008-01-01

    ABSTRACT Lhasa Limited is a not-for-profit organization that exists to promote the sharing of data and knowledge in chemistry and the life sciences. It has developed the software tools Derek for Windows, Meteor, and Vitic to facilitate such sharing. Derek for Windows and Meteor are knowledge-based expert systems that predict the toxicity and metabolism of a chemical, respectively. Vitic is a chemically intelligent toxicity database. An overview of each software system is provided along with examples of the sharing of data and knowledge in the context of their development. These examples include illustrations of (1) the use of data entry and editing tools for the sharing of data and knowledge within organizations; (2) the use of proprietary data to develop nonconfidential knowledge that can be shared between organizations; (3) the use of shared expert knowledge to refine predictions; (4) the sharing of proprietary data between organizations through the formation of data-sharing groups; and (5) the use of proprietary data to validate predictions. Sharing of chemical toxicity and metabolism data and knowledge in this way offers a number of benefits including the possibilities of faster scientific progress and reductions in the use of animals in testing. Maximizing the accessibility of data also becomes increasingly crucial as in silico systems move toward the prediction of more complex phenomena for which limited data are available.

  18. Soils of Walker Branch Watershed

    SciTech Connect

    Lietzke, D.A.

    1994-03-01

    The soil survey of Walker Branch Watershed (WBW) utilized the most up-to-date knowledge of soils, geology, and geohydrology in building the soils data base needed to reinterpret past research and to begin new research in the watershed. The soils of WBW were also compared with soils mapped elsewhere along Chestnut Ridge on the Oak Ridge Reservation to (1) establish whether knowledge obtained elsewhere could be used within the watershed, (2) determine whether there were any soils restricted to the watershed, and (3) evaluate geologic formation lateral variability. Soils, surficial geology, and geomorphology were mapped at a scale of 1:1,200 using a paper base map having 2-ft contour intervals. Most of the contours seemed to reasonably represent actual landform configurations, except for dense wooded areas. For example, the very large dolines or sinkholes were shown on the contour base map, but numerous smaller ones were not. In addition, small drainageways and gullies were often not shown. These often small but important features were located approximately as soil mapping progressed.

  19. The Walker Lane in northeastern California

    SciTech Connect

    Saucedo, G.J.; Wagner, D.L.; Grose, T.L.T.

    1990-01-01

    The Walker Lane (Locke and others, 1940) was defined as a narrow northwest-trending dextral fault zone that separates basin- and range topography on the east from diverse topography on the west that extends discontinuously from Lake Mead to Honey Lake. The term Walker Lane Belt (Steward, 1988) expands the feature to include a wide zone east of the Sierra Nevada. Pease (1969), Hannah (1977), and Grose (1986) suggested that the tectonic characteristics of Walker Lane continue into the Modoc Plateau. The authors believe that it is useful to recognize the Walker Lane or Walker Lane Belt in the Modoc Plateau. Within the Modoc Plateau, a 25-km wide (15-mile wide) zone of northwest-southeast faults herein recognized as the Walker Lane, trends N35{degree}W from Honey Lake Basin to Medicine Lake Highland. Mapping in the Eagle Lake area revealed northwest-southeast, north-south, and northeast-southwest late Quaternary faults and rifts, eruptive fissures, small tectonic depressions, and the large Eagle Lake volcano-tectonic depression. To the east is a remarkably unfaulted Neogene volcanic terrane extending 70 km (42 miles) eastward to the Dry Valley-Smoke Creek Desert fault system in Nevada. To the west in the Cascades complex late Pliocene-Quaternary faulting, linear basaltic cones, and andesite volcanoes are all aligned N15{degree}-30{degree}W. This Modoc part of the Walker Lane Belt displays blocks tilted mostly 3{degree}-10{degree}E bounded by west-dipping normal faults and right diagonal normal faults. Left stepping north-south trending rifts occur within northwest trending, straight right diagonal-slip fault zones.

  20. Boltzmann active walkers and rough surfaces

    NASA Astrophysics Data System (ADS)

    Pochy, R. D.; Kayser, D. R.; Aberle, L. K.; Lam, L.

    1993-06-01

    An active walker model (AWM) was recently proposed by Freimuth and Lam for the generation of various filamentary patterns. In an AWM, the walker changes the landscape as it walks, and its steps are in turn influenced by the changing landscape. The landscape so obtained is a rough surface. In this paper, the properties of such a rough surface (with average height conserved) generated by a Boltzmann active walker in 1 + 1 dimensions is investigated in detail. The scaling properties of the surface thickness σ T is found to belong to a new class quite different from other types of fractal surfaces. For example, σ T is independent of the system size L, but is a function of the “temperature” T. Soliton propagation is found when T = 0.

  1. Soils of Walker Branch Watershed

    SciTech Connect

    Lietzke, D.A.

    1994-01-01

    The soil survey of Walker Branch Watershed (WBW) utilized the most up-to-date knowledge of soils, geology, and geohydrology in building the soils data base needed to reinterpret past research and to begin new research in the watershed. The soils of WBW were also compared with soils mapped elsewhere along Chestnut Ridge on the Oak Ridge Reservation to (1) establish whether knowledge obtained elsewhere could be used within the watershed, (2) determine whether there were any soils restricted to the watershed, and (3) evaluate geologic formation lateral variability. Soils, surficial geology, and geomorphology were mapped at a scale of 1:1200 using a paper base map having 2-ft contour intervals. Most of the contours seemed to reasonably represent actual landform configurations, except for dense wooded areas. For example, the very large dolines or sinkholes were shown on the contour base map, but numerous smaller ones were not. In addition, small drainageways and gullies were often not shown. These often small but important features were located approximately as soil mapping progressed. WBW is underlain by dolostones of the Knox Group, but only a very small part of the surface area contains outcroppings of rock and most outcrops were located in the lower part. Soil mapping revealed the presence of both ancient alluvium and ancient colluvium deposits, not recognized in previous soil surveys, that have been preserved in high-elevation stable portions of present-day landforms. An erosional geomorphic process of topographic inversion requiring several millions of years within the Pleistocene is necessary to bring about the degree of inversion that is expressed in the watershed. Indeed, some of these ancient alluvial and colluvial remnants may date back into the Tertiary. Also evident in the watershed, and preserved in the broad, nearly level bottoms of dolines, are multiple deposits of silty material either devoid or nearly devoid of coarse fragments. Recent research

  2. Walker Calhoun: Cherokee Song and Dance Man. Interview.

    ERIC Educational Resources Information Center

    Olson, Ted

    1995-01-01

    Born in 1918, the youngest of 12 children, Walker Calhoun describes growing up on the Cherokee Reservation in North Carolina. The schools turned the Cherokee against their old ways, but Walker learned many old songs and dances from his uncle, Will West. Since retirement, Walker has taught the dances and songs to children. His material has been…

  3. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... (applicable to walkers equipped with parking brakes)—The walker shall have a maximum displacement of 1.97... ASTM F 977-07, comply with the following: (i) 8.2.3.3 If the walker is equipped with a parking brake, a warning statement shall address the following: WARNING: Parking brake use does not totally prevent...

  4. Walker River Paiutes: A Tribal History.

    ERIC Educational Resources Information Center

    Johnson, Edward C.

    The Northern Paiute people of Nevada's Walker Lake area were known as the Agai Diccutta (Trout Eaters); they called themselves the Numa, or the People. For as long as anyone could recall, they had lived in the area, catching the huge trout from the lake and harvesting the pinon nuts and other foods from the surrounding desert. In the 1820's the…

  5. Gender Recognition from Point-Light Walkers

    ERIC Educational Resources Information Center

    Pollick, Frank E.; Kay, Jim W.; Heim, Katrin; Stringer, Rebecca

    2005-01-01

    Point-light displays of human gait provide information sufficient to recognize the gender of a walker and are taken as evidence of the exquisite tuning of the visual system to biological motion. The authors revisit this topic with the goals of quantifying human efficiency at gender recognition. To achieve this, the authors first derive an ideal…

  6. Vicious walkers, friendly walkers and Young tableaux: II. With a wall

    NASA Astrophysics Data System (ADS)

    Krattenthaler, Christian; Guttmann, Anthony J.; Viennot, Xavier G.

    2000-12-01

    We derive new results for the number of star and watermelon configurations of vicious walkers in the presence of an impenetrable wall by showing that these follow from standard results in the theory of Young tableaux and combinatorial descriptions of symmetric functions. For the problem of n friendly walkers, we derive exact asymptotics for the number of stars and watermelons, both in the absence of a wall and in the presence of a wall.

  7. Walker circulation in a transient climate

    NASA Astrophysics Data System (ADS)

    Plesca, Elina; Grützun, Verena; Buehler, Stefan A.

    2016-04-01

    The tropical overturning circulations modulate the heat exchange across the tropics and between the tropics and the poles. The anthropogenic influence on the climate system will affect these circulations, impacting the dynamics of the Earth system. In this work we focus on the Walker circulation. We investigate its temporal and spatial dynamical changes and their link to other climate features, such as surface and sea-surface temperature patterns, El-Niño Southern Oscillation (ENSO), and ocean heat-uptake, both at global and regional scale. In order to determine the impact of anthropogenic climate change on the tropical circulation, we analyze the outputs of 28 general circulation models (GCMs) from the CMIP5 project. We use the experiment with 1% year-1 increase in CO2 concentration from pre-industrial levels to quadrupling of the concentration. Consistent with previous studies (ex. Ma and Xie 2013), we find that for this experiment most GCMs associate a weakening Walker circulation to a warming transient climate. Due to the role of the Walker Pacific cell in the meridional heat and moisture transport across the tropical Pacific and also the connection to ENSO, we find that a weakened Walker circulation correlates with more extreme El-Niño events, although without a change in their frequency. The spatial analysis of the Pacific Walker cell suggests an eastward displacement of the ascending branch, which is consistent with positive SST anomalies over the tropical Pacific and the link of the Pacific Walker cell to ENSO. Recent studies (ex. England et al. 2014) have linked a strengthened Walker circulation to stronger ocean heat uptake, especially in the western Pacific. The inter-model comparison of the correlation between Walker circulation intensity and ocean heat uptake does not convey a robust response for the investigated experiment. However, there is some evidence that a stronger weakening of the Walker circulation is linked to a higher transient climate

  8. Obituary: Robert Mowbray Walker, 1929-2004

    NASA Astrophysics Data System (ADS)

    Schoenherr, Neil T.

    2004-12-01

    Robert M. Walker, PhD, Professor of Physics in Arts & Sciences and a faculty fellow of the McDonnell Center for the Space Sciences, died of stomach cancer Thursday, 12 February 2004, in Brussels, Belgium. He was 75. Walker worked on the frontiers of space research for more than four decades. Robert Walker was born in Philadelphia on 6 February 1929. His mother was Dorothy Potter and he considered Roger Potter his father though he was not his biological father. His early years were spent in New York City and in upstate New York. He attended the Bronx High School of Science, earned his BS in physics from Union College and in 1954, he received his PhD in particle physics from Yale University. He subsequently joined the General Electric Laboratory in Schenectady, New York where he studied the radiation effects in solids. His work on defects in irradiated copper is still regarded as the definitive work on the topic. In the early 1960s, Walker's discovery of fossil nuclear particle tracks in minerals was instrumental to new developments in geo-chronology and cosmic ray physics. In particular, his discovery of tracks from nuclei heavier than iron opened a new frontier of cosmic ray physics. He subsequently pioneered the use of plastics to detect and count such nuclei in cosmic ray balloon flights. Beginning in 1966, when he moved to Washington University and became the first McDonnell Professor of Physics, his research interests turned more toward space physics. He was the inaugural director of the McDonnell Center, which was established in 1975 by a gift from aerospace pioneer James S. McDonnell. Walker was a member of the NASA committee that allocated samples of the first returned lunar materials, and his laboratory led the way in deciphering their record of lunar, solar system and galactic evolution. Together with Ghislaine Crozaz and other colleagues, Walker made path breaking laboratory studies of the first moon rocks revealing the history of solar radiation and

  9. Modern lacustrine stromatolites, Walker Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Osborne, Robert H.; Licari, Gerald R.; Link, Martin H.

    1982-05-01

    The Walker River drainage basin occupies about 10,000 km 2 in western Nevada and parts of California and is essentially a closed hydrologic system which drains from the crest of the Sierra Nevada in California and terminates in Walker Lake, Nevada. Walker Lake trends north and is about 27.4 km long and 8 km wide with water depths exceeding 30.5 m. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and more gentle but areally more extensive alluvial fans flanking the eastern shoreline (Gillis Range). Exposed lake terraces and the present shoreline of Walker Lake record a sequence of Pleistocene and Holocene stromatolitic and tufaceous carbonate deposits. Small generalized and columnar stromatolites, frequently encrusted on exposed coarse-grained clasts or bedrock, are present along parts of the nearshore margin of Walker Lake and at elevated lake stands. Columnar stromatolites as much as 4 cm high are subcylindrical to club shaped discrete, and laterally linked at the base with local branching. These digitate stromatolites start as wavy, generalized stromatolites which are vertically transitional to small, laterally linked cabbage heads with laminae which thicken over the crests. Although algal structures are not well preserved in the older stromatolites, recent precipitation of low magnesium calcite occurs as smooth encrustations and as tiny mounds which are consistently associated with a diverse, seasonally variable, green and blue-green algal community including Cladophora glomerata, Ulothrix (cf. aequalis), Gongrosira, Schizothrix, Amphithrix janthina, Calothrix, Homeothrix, Spirulina, Anabaena, Lyngbya, and Entophysalis. Cladophora glomerata and a species of Ulothrix, which are the two most abundant algae within the Walker Lake stromatolite community, are known to condition semi-alkaline lake water by the removal of CO 2 from bicarbonate during photosynthesis. Such conditioning results in the

  10. Vibrotactile Guidance for Wayfinding of Blind Walkers.

    PubMed

    Flores, German; Kurniawan, Sri; Manduchi, Roberto; Martinson, Eric; Morales, Lourdes M; Sisbot, Emrah Akin

    2015-01-01

    We propose a vibrotactile interface in the form of a belt for guiding blind walkers. This interface enables blind walkers to receive haptic directional instructions along complex paths without negatively impacting users' ability to listen and/or perceive the environment the way some auditory directional instructions do. The belt interface was evaluated in a controlled study with 10 blind individuals and compared to the audio guidance. The experiments were videotaped and the participants' behaviors and comments were content analyzed. Completion times and deviations from ideal paths were also collected and statistically analyzed. By triangulating the quantitative and qualitative data, we found that the belt resulted in closer path following to the expense of speed. In general, the participants were positive about the use of vibrotactile belt to provide directional guidance. PMID:25781953

  11. A review of 404 'late walkers'.

    PubMed

    Chaplais, J D; Macfarlane, J A

    1984-06-01

    A survey of all known 18 month old Oxfordshire children who had not yet walked unassisted and who were born in the four year period between July 1, 1976 and June 30, 1980 was carried out. A total of 275 children aged 18 months with no previously suspected cause for late walking were referred by health visitors; 257 of these children were assessed neurologically and developmentally by a paediatrician at home. Nine cases of cerebral palsy (3 X 5%) and 6 cases of minor neurological abnormality (2 X 3%) were newly diagnosed. A register of all other 18 month old 'late walkers' (129) who were already known to paediatricians and were either normal (17) or had known causes for late walking (112) was compiled for the same four year period. The total incidence of pathology among all late walkers (404) in these two groups was 32%.

  12. Space Walker - the Cognitive Visualization System

    NASA Astrophysics Data System (ADS)

    Komarinskiy, S.; Vitkovskiy, V. V.; Gorohov, V.; Zakharevski, D.

    2008-08-01

    The data cognitive visualization system --- ``Space Walker'' is presented. The creation of program products requires the practical mastery of the entire complex of achievements in the field of mathematical statistics, theory of illegible sets, cognitive machine drawing, cognitive psychology and theory of knowledge. SW system base on the ground of possibility use already acting program software intellectual support adopted solution in task control complex system with deep a priori uncertainty.

  13. Active walker models: tracks and landscapes

    NASA Astrophysics Data System (ADS)

    Kayser, D. R.; Aberle, L. K.; Pochy, R. D.; Lam, L.

    1992-12-01

    The track patterns from the active walker models (AWMs) are compared with experimental retinal neuron and dielectric breakdown of liquid patterns, respectively. Excellent qualitative and quantitative agreements are obtained. The landscapes from the Boltzmann AWM in 1 + 1 dimensions form rough surfaces, with a first-order phase transition as the height of the landscaping function W0 is varied. Landscapes and statistics of the tracks from the probabilistic AWM in 2 + 1 dimensions are presented.

  14. Auditory perception of a human walker.

    PubMed

    Cottrell, David; Campbell, Megan E J

    2014-01-01

    When one hears footsteps in the hall, one is able to instantly recognise it as a person: this is an everyday example of auditory biological motion perception. Despite the familiarity of this experience, research into this phenomenon is in its infancy compared with visual biological motion perception. Here, two experiments explored sensitivity to, and recognition of, auditory stimuli of biological and nonbiological origin. We hypothesised that the cadence of a walker gives rise to a temporal pattern of impact sounds that facilitates the recognition of human motion from auditory stimuli alone. First a series of detection tasks compared sensitivity with three carefully matched impact sounds: footsteps, a ball bouncing, and drumbeats. Unexpectedly, participants were no more sensitive to footsteps than to impact sounds of nonbiological origin. In the second experiment participants made discriminations between pairs of the same stimuli, in a series of recognition tasks in which the temporal pattern of impact sounds was manipulated to be either that of a walker or the pattern more typical of the source event (a ball bouncing or a drumbeat). Under these conditions, there was evidence that both temporal and nontemporal cues were important in recognising theses stimuli. It is proposed that the interval between footsteps, which reflects a walker's cadence, is a cue for the recognition of the sounds of a human walking.

  15. Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

    USGS Publications Warehouse

    Lopes, Thomas J.; Allander, Kip K.

    2009-01-01

    The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. The only outflow from Walker Lake is evaporation from the lake surface. Between 1882 and 2008, upstream agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-feet. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes streamflow in the Walker River basin and an updated water budget of Walker Lake with emphasis on the lower Walker River basin downstream from Wabuska, Nevada. Water budgets are based on average annual flows for a 30-year period (1971-2000). Total surface-water inflow to the upper Walker River basin upstream from Wabuska was estimated to be 387,000 acre-feet per year (acre-ft/yr). About 223,000 acre-ft/yr (58 percent) is from the West Fork of the Walker River; 145,000 acre-ft/yr (37 percent) is from the East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) is from the Sweetwater Range; and 2,000 acre-ft/yr (less than 1 percent) is from the Bodie Mountains, Pine Grove Hills, and western Wassuk Range. Outflow from the upper Walker River basin is 138,000 acre-ft/yr at Wabuska. About 249,000 acre-ft/yr (64 percent) of inflow is diverted for irrigation, transpired by riparian vegetation, evaporates from lakes and reservoirs, and recharges alluvial aquifers. Stream losses in Antelope, Smith, and Bridgeport Valleys are due to evaporation from reservoirs and agricultural diversions with negligible stream infiltration or riparian evapotranspiration. Diversion rates in Antelope and Smith Valleys were estimated to be 3.0 feet per year (ft/yr) in each valley. Irrigated fields receive an additional 0.8 ft of precipitation, groundwater pumpage, or both for a total applied-water rate

  16. A walking prescription for statically-stable walkers based on walker/terrain interaction

    NASA Technical Reports Server (NTRS)

    Nagy, Peter V.; Whittaker, William L.; Desa, Subhas

    1992-01-01

    The walker/terrain interaction phenomena for the control of a statically stable walking machine are described. The algorithms, measures, and knowledge of walker/terrain interaction phenomena are then combined to form a prescription for how to walk on general terrain. This prescription consists of two parts: nominal control and reactive control. The function of nominal control is the evaluation and execution of planned motions, based on predicted foot force redistributions, to achieve reliable locomotion. The function of reactive control is the monitoring of walker/terrain interaction in real-time to detect anomalous conditions and then respond with the appropriate reflexive actions. Simulations and experiments have been used to test and verify various aspects of the walking prescription.

  17. Prevention strategies for infant walker-related injuries.

    PubMed Central

    Trinkoff, A; Parks, P L

    1993-01-01

    The estimated number of walker-related injuries to infants increased during the 1980s, and standards for walker design safety remain voluntary with no monitoring to assess compliance. Although banning the walker has been proposed, this prevention strategy has not been employed. The most recent statistics available indicate that there were an estimated 27,804 walker-related injuries requiring emergency room attention among ages 0-4 years in 1991. Results of a survey of parents of 3-12-month-olds indicated considerable use of walkers, with greater use among parents with lower educational levels. Reported reasons for using walkers were for the infant's entertainment, enjoyment, and containment, as well as to help infants learn to walk. The authors recommend the consideration of a series of preventive strategies according to the epidemiologic framework for injury control and prevention designed by William Haddon, Jr. These include, but are not limited to, prohibiting the manufacture and sale of the walker, mandatory standards, redesign of the walker, design of an alternative to the walker, and consumer education to reduce use and to change patterns of use. PMID:8265765

  18. Walker Ranch 3D seismic images

    DOE Data Explorer

    Robert J. Mellors

    2016-03-01

    Amplitude images (both vertical and depth slices) extracted from 3D seismic reflection survey over area of Walker Ranch area (adjacent to Raft River). Crossline spacing of 660 feet and inline of 165 feet using a Vibroseis source. Processing included depth migration. Micro-earthquake hypocenters on images. Stratigraphic information and nearby well tracks added to images. Images are embedded in a Microsoft Word document with additional information. Exact location and depth restricted for proprietary reasons. Data collection and processing funded by Agua Caliente. Original data remains property of Agua Caliente.

  19. Obituary: Robert Mowbray Walker, 1929-2004

    NASA Astrophysics Data System (ADS)

    Schoenherr, Neil T.

    2004-12-01

    Robert M. Walker, PhD, Professor of Physics in Arts & Sciences and a faculty fellow of the McDonnell Center for the Space Sciences, died of stomach cancer Thursday, 12 February 2004, in Brussels, Belgium. He was 75. Walker worked on the frontiers of space research for more than four decades. Robert Walker was born in Philadelphia on 6 February 1929. His mother was Dorothy Potter and he considered Roger Potter his father though he was not his biological father. His early years were spent in New York City and in upstate New York. He attended the Bronx High School of Science, earned his BS in physics from Union College and in 1954, he received his PhD in particle physics from Yale University. He subsequently joined the General Electric Laboratory in Schenectady, New York where he studied the radiation effects in solids. His work on defects in irradiated copper is still regarded as the definitive work on the topic. In the early 1960s, Walker's discovery of fossil nuclear particle tracks in minerals was instrumental to new developments in geo-chronology and cosmic ray physics. In particular, his discovery of tracks from nuclei heavier than iron opened a new frontier of cosmic ray physics. He subsequently pioneered the use of plastics to detect and count such nuclei in cosmic ray balloon flights. Beginning in 1966, when he moved to Washington University and became the first McDonnell Professor of Physics, his research interests turned more toward space physics. He was the inaugural director of the McDonnell Center, which was established in 1975 by a gift from aerospace pioneer James S. McDonnell. Walker was a member of the NASA committee that allocated samples of the first returned lunar materials, and his laboratory led the way in deciphering their record of lunar, solar system and galactic evolution. Together with Ghislaine Crozaz and other colleagues, Walker made path breaking laboratory studies of the first moon rocks revealing the history of solar radiation and

  20. Why is walker-assisted gait metabolically expensive?

    PubMed

    Priebe, Jonathon R; Kram, Rodger

    2011-06-01

    Walker-assisted gait is reported to be ∼200% more metabolically expensive than normal bipedal walking. However, previous studies compared different walking speeds. Here, we compared the metabolic power consumption and basic stride temporal-spatial parameters for 10 young, healthy adults walking without assistance and using 2-wheeled (2W), 4-wheeled (4W) and 4-footed (4F) walker devices, all at the same speed, 0.30m/s. We also measured the metabolic power demand for walking without any assistive device using a step-to gait at 0.30m/s, walking normally at 1.25m/s, and for repeated lifting of the 4F walker mimicking the lifting pattern used during 4F walker-assisted gait. Similar to previous studies, we found that the cost per distance walked was 217% greater with a 4F walker at 0.30m/s compared to unassisted, bipedal walking at 1.25m/s. Compared at the same speed, 0.30m/s, using a 4F walker was still 82%, 74%, and 55% energetically more expensive than walking unassisted, with a 4W walker and a 2W walker respectively. The sum of the metabolic cost of step-to walking plus the cost of lifting itself was equivalent to the cost of walking with a 4F walker. Thus, we deduce that the high cost of 4F walker assisted gait is due to three factors: the slow walking speed, the step-to gait pattern and the repeated lifting of the walker.

  1. AmeriFlux US-WBW Walker Branch Watershed

    SciTech Connect

    Meyers, Tilden

    2016-01-01

    This is the AmeriFlux version of the carbon flux data for the site US-WBW Walker Branch Watershed. Site Description - The stand is over 50 years old, having regenerated from agricultural land.This site is located near Oak Ridge, Tennessee near the Walker Branch Watershed.

  2. 75 FR 35265 - Safety Standard for Infant Walkers: Final Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... walkers in the Federal Register on September 3, 2009. 74 FR 45704. The standard is substantially the same... walkers, which were originally issued in 1971 by the Food and Drug Administration. 16 CFR 1500.18(a)(6... rule (74 FR at 45705), the stair fall protection provisions in the ASTM standard dramatically...

  3. Hydrogel Walkers with Electro-Driven Motility for Cargo Transport

    PubMed Central

    Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-01-01

    In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two “legs” for walking. The hydrogel walkers can reversibly bend and stretch via repeated “on/off” electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two “legs” to achieve one-directional walking motion on a rough surface via repeated “on/off” electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation. PMID:26314786

  4. Older Homebound Women: Negotiating Reliance on a Cane or Walker

    PubMed Central

    Porter, Eileen J.; Benson, Jacquelyn J.; Matsuda, Sandy

    2012-01-01

    Canes and walkers are commonly characterized as assistive devices and as devices that serve the same purpose, as walking aides. These general views were reappraised and tempered in this descriptive phenomenological study with 40 older women (aged 85-98) who were unable to leave their homes without help. The purpose was to describe the phenomena of negotiating reliance on canes and walkers as walking devices and the lifeworld context underlying each phenomenon. Relative to lifeworld, there were differences between coming to terms with using a cane and coming to terms with using a walker. Data revealed similarities and distinctions between the basic intentions of relying on canes and on walkers and the associated purposes served by canes and walkers. Participants did not view either device as consistently assistive. Findings evoke opportunities for dialogue among older persons, scholars, practitioners, and designers of these devices about coming to terms with such devices and relying on them. PMID:21041520

  5. Hydrogel Walkers with Electro-Driven Motility for Cargo Transport

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

    2015-08-01

    In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two “legs” for walking. The hydrogel walkers can reversibly bend and stretch via repeated “on/off” electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two “legs” to achieve one-directional walking motion on a rough surface via repeated “on/off” electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation.

  6. David Alan Walker (1928-2012).

    PubMed

    Edwards, Gerald E; Heber, Ulrich

    2012-06-01

    David Alan Walker, Emeritus Professor of Biology, University of Sheffield, UK and Fellow of the Royal Society, died on February 13, 2012. David had a marvelous 60 year career as a scientist, during which he was a researcher, mentor, valued colleague, and a prolific writer in the field of photosynthesis. His career was marked by creative breakthroughs in isolation and analysis of chloroplast metabolism in vitro and simple but valuable technical advances for measurement of photosynthesis in vivo that remain relevant on a global scale to production of crops and biofuels, as well as plant responses to climate change. We include here personal remembrances by the authors (GEE and UH), and by (in alphabetical order): Zoran Cerovic (France), Bob Furbank (Australia), Geoffrey Hind (USA), John Humby (UK), Agu Laisk (Estonia), Peter Lea (UK), Ross Lilley (Australia), Barry Osmond (Australia), Simon Robinson (Australia) and Charles Stirling (UK). PMID:22638915

  7. Gender recognition from point-light walkers.

    PubMed

    Pollick, Frank E; Kay, Jim W; Heim, Katrin; Stringer, Rebecca

    2005-12-01

    Point-light displays of human gait provide information sufficient to recognize the gender of a walker and are taken as evidence of the exquisite tuning of the visual system to biological motion. The authors revisit this topic with the goals of quantifying human efficiency at gender recognition. To achieve this, the authors first derive an ideal observer for gender recognition on the basis of center of moment (J. E. Cutting, D. R. Proffitt, & L. T. Kozlowski, 1978) and, with the use of anthropometric data from various populations, show optimal recognition of approximately 79% correct. Next, they perform a meta-analysis of 21 experiments examining gender recognition, obtaining accuracies of 66% correct for a side view and 71% for other views. Finally, results of the meta-analysis and the ideal observer are combined to obtain estimates of human efficiency at gender recognition of 26% for the side view and 47% for other views. PMID:16366787

  8. Three Views of the River: Three Reviews of "The Shape of the River: Long-Term Consequences of Considering Race in College and University Admissions" by William G. Bowen and Derek Bok.

    ERIC Educational Resources Information Center

    Chavez, Linda; Lerner, Robert; O'Neill, Dave; Clegg, Roger

    This paper presents three reviews of the book, "The Shape of the River: Long-Term Consequences of Considering Race in College and University Admissions," by William Bowen and Derek Bok. The book defends affirmative action in college admissions. The first review says that the book presents important data, but it is seriously flawed overall because…

  9. Dandy-Walker Malformation Presenting with Psychological Manifestations.

    PubMed

    Rohanachandra, Yasodha Maheshi; Dahanayake, Dulangi Maneksha Amerasinghe; Wijetunge, Swarna

    2016-01-01

    Dandy-Walker malformation, which is a congenital malformation of the cerebellum, is documented in literature to be associated with psychotic symptoms, obsessive compulsive symptoms, mood symptoms, hyperactivity, and impulsive behavior. The pathogenesis of psychiatric symptoms in Dandy-Walker malformation is thought to be due to disruption of the corticocerebellar tracts, resulting in what is known as cerebellar cognitive affective syndrome. We present a case of Dandy-Walker malformation presenting with psychiatric symptoms. This case highlights the necessity to be aware of psychiatric manifestations of cerebellar disease as it has an impact on the diagnosis and treatment. PMID:27493822

  10. Dandy-Walker Malformation Presenting with Psychological Manifestations

    PubMed Central

    Dahanayake, Dulangi Maneksha Amerasinghe

    2016-01-01

    Dandy-Walker malformation, which is a congenital malformation of the cerebellum, is documented in literature to be associated with psychotic symptoms, obsessive compulsive symptoms, mood symptoms, hyperactivity, and impulsive behavior. The pathogenesis of psychiatric symptoms in Dandy-Walker malformation is thought to be due to disruption of the corticocerebellar tracts, resulting in what is known as cerebellar cognitive affective syndrome. We present a case of Dandy-Walker malformation presenting with psychiatric symptoms. This case highlights the necessity to be aware of psychiatric manifestations of cerebellar disease as it has an impact on the diagnosis and treatment. PMID:27493822

  11. Dandy-Walker malformation in Ellis-van Creveld syndrome.

    PubMed

    Zangwill, K M; Boal, D K; Ladda, R L

    1988-09-01

    We report on 2 Old Order Amish patients with Ellis-van Creveld (EvC) syndrome and the Dandy-Walker malformation; a similar case is noted in the literature. Pedigree analysis of our patients documents extensive inbreeding in successive generations. Considering the rarity of EvC syndrome and Dandy-Walker malformation as isolated malformations, the appearance of both in our 2 patients plus the patient in the literature suggests that Dandy-Walker malformation may be a manifestation in the EvC syndrome. However, in this isolate the coincidental occurrence of 2 rare recessive traits cannot be excluded. PMID:3223493

  12. Test pilots 1952 - Walker, Butchart, and Jones

    NASA Technical Reports Server (NTRS)

    1952-01-01

    This photo shows test pilots, (Left-Right) Joseph A. Walker, Stanley P. Butchart and Walter P. Jones, standing in front of the Douglas D-558-II Skystreak, in 1952. These three test pilots at the National Advisory Committee for Aeronautics' High-Speed Flight Research Station probably were discussing their flights in the aircraft. Joe flew research flights on the D-558-I #3 (14 flights, first on June 29, 1951) investigating buffeting, tail loads, and longitudinal stability. He flew the D-558-II #2 (3 flights, first on April 29, 1955) and recorded data on lateral stability and control. He also made pilot check-out flights in the D-558-II #3 (2 flights, first on May 7, 1954). For fifteen years Walker served as a pilot at the Edwards flight research facility (today known as the National Aeronautics and Space Administration's Dryden Flight Research Center) on research flights as well as chase missions for other pilots on NASA and Air Force research programs. On June 8, 1966, he was flying chase in NASA's F-104N for the Air Force's experimental bomber, North American XB-70A, when he was fatally injured in a mid-air collision between the planes. Stan flew the D-558-I #3 (12 flights, first on October 19, 1951) to determine the dynamic longitudinal stability characteristics and investigations of the lateral stability and control. He made one flight in the D-558-II #3 on June 26, 1953, as a pilot check-out flight. Butchart retired from the NASA Dryden Flight Research Center at Edwards, California, on February 27, 1976, after a 25-year career in research aviation. Stan served as a research pilot, chief pilot, and director of flight operations. Walter P. Jones was a research pilot for NACA from the fall of 1950 to July 1952. He had been in the U.S. Air Force as a pilot before joining the Station. Jones flew the D-558-I #3 (5 flights, first on February 13, 1951) to study buffeting, tail loads and longitudinal stability. Jones made research flights on the D-558-II #3 ( 7 flights

  13. The Northern Walker Lane Seismic Refraction Experiment

    NASA Astrophysics Data System (ADS)

    Louie, J. N.; Smith, S. B.; Thelen, W.; Scott, J. B.; Clark, M.

    2002-12-01

    We are developing a three-dimensional reference seismic velocity model for the western Great Basin region of Nevada and eastern California. The northern Walker Lane had not been characterized well by previous work. In May 2002 we collected a new crustal refraction profile from Battle Mountain, Nev. across western Nevada, the Reno area, Lake Tahoe, and the northern Sierra to Auburn, Calif. Mine blasts and earthquakes were recorded by 199 Texan instruments (loaned by the PASSCAL Instrument Center) extending across this more than 450-km-long transect. The seismic sources at the eastern end were mining blasts at Barrick's GoldStrike pit. We recorded additional blasts at the Florida Canyon and other mines between Lovelock and Battle Mountain, Nevada. The GoldStrike mine produced several ripple-fired blasts using 10,000-40,000 kg of ANFO each. First arrivals from the larger blasts are obvious to distances exceeding 250 km in the raw records. A M2.4 earthquake near Bridgeport, Calif. also produced pickable P-wave arrivals across at least half the transect, providing fan-shot data. We recorded only during working hours, and so missed an M4 earthquake that occurred at night. Events of M2 occurred during our recording to the west on the San Andreas fault near Pinnacles, Calif.; M3 events occurred near Portola and Mammoth Lakes, Calif. Arrivals from M5 events in the Mariana and Kuril Islands also appear in the records. Time-picks from these earthquakes may be possible after more work on synthetic-time modeling, data filtering, and display. We plan to record blasts at quarries in the western Sierra in future experiments, for a direct refraction reversal. We will compare our time picks against times generated from regional velocity models, to identify potential crustal and upper-mantle velocity anomalies. Such anomalies may be associated with the Battle Mountain heat-flow high, the northern Walker Lane belt, or the northern Sierran block.

  14. A critical commentary on Derek Morgan's unpublished manuscript: 'coming Back to Life: The Normal Chaos of Medical Law' and how to deal with property in human cells.

    PubMed

    Capps, Benjamin J

    2014-01-01

    This article is an analysis of Derek Morgan's manuscript-'Coming Back to Life: The Normal Chaos of Medical Law', which remained unpublished at his death in 2011. Morgan made two claims in the manuscript: (1) medical practitioners and patients approach health from the different perspectives of 'reason' and 'emotion' respectively, while medical law treads the line between these ultimately resulting in 'normal chaos'. (2) In this respect, medical law ought to be coaxed 'back to life' so that it can address broader principles and values in respect to practical resolution; however, it has, in the face of this chaos, become dull in its ambitions. In this article, I first analyse these two claims in detail, before, second, illustrating the 'normal chaos' of medical law using the debate over ownership of human cells and tissues. I draw my own conclusions as to whether Morgan's final thesis was successful. PMID:24525529

  15. View northwest, Brandywine Creek with Walkers Mill on right, Brecks ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View northwest, Brandywine Creek with Walkers Mill on right, Brecks Mill on left, and the Charles I. Du Pont House in center background - Charles I. Du Pont House, 162 Main Street, Wilmington, New Castle County, DE

  16. ISS Update: Orion Recovery and Rescue Lead Tom Walker

    NASA Video Gallery

    NASA Public Affairs Officer Brandi Dean talks with Tom Walker, Orion Recovery and Rescue Lead, about how the Neutral Buoyancy Laboratory (NBL) is being used to train rescue and recovery personnel f...

  17. Walker's Critique of Religion in "The Color Purple."

    ERIC Educational Resources Information Center

    Mercer, Calvin

    1989-01-01

    Highlights religious themes in Alice Walker's "The Color Purple," especially Celie's struggle with traditional Christianity, which here serves to reinforce oppression. Her journey toward spiritual independence reflects much of the actual religious experience of Black women in America. (DM)

  18. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... (for CAMI dummy scenario) = weight of CAMI dummy and walker g = acceleration of gravity = 32.2 ft/sec2... weight g = acceleration of gravity = 32.2 ft/sec2 (ii) (10) In addition to complying with section 7.6.3.6... of CAMI dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the swivel wheels...

  19. Lonomia obliqua Walker (Lepidoptera: Saturniidae): hemostasis implications.

    PubMed

    Maggi, Silviane; Faulhaber, Gustavo Adolpho Moreira

    2015-01-01

    In southern Brazil, since 1989, several cases of accidents produced by unwilling contact with the body of poisonous caterpillars of the moth species Lonomia obliqua Walker, 1855 (Lepidoptera: Saturniidae), were described. L. obliqua caterpillars have gregarious behavior and feed on leaves of host trees during the night, staying grouped in the trunk during the day, which favors the occurrence of accidents with the species. This caterpillar has the body covered with bristles that on contact with the skin of individuals, breaks and release their contents, inoculating the venom into the victim. The basic constitution of the venom is protein and its components produce physiological changes in the victim, which include disturbances in hemostasis. Hemorrhagic syndrome associated with consumption coagulopathy, intravascular hemolysis and acute renal failure are some of the possible clinical manifestations related to poisoning by L. obliqua. Specific laboratory tests for diagnosis of poisoning have not been described previously. The diagnosis of poisoning is made based on the patient's medical history, clinical manifestations, erythrocyte levels, and, primarily, parameters that evaluate blood coagulation. Treatment is performed with the use of supportive care and the administration of specific hyperimmune antivenom. Poisoning can be serious and even fatal. PMID:26248250

  20. The Walker Lane Belt in northeastern California

    SciTech Connect

    Grose, T.L.T. . Dept. of Geology and Geological Engineering)

    1993-04-01

    The Walker Lane Belt (WLB) has been suspected to significantly project NW-ward into NE CA from the Pyramid Lake-Honey Lake area which has been generally regarded as its northwestern terminus. Within the WLB, most of the exposed rocks are Miocene to Late Quaternary (10--0.1 Ma) volcanics, mainly andesitic, but significantly rhyolitic and basaltic. The Hayden Hill Au mine within a Mid-Miocene NNW-SSE volcanotectonic depression and the Quaternary NE-SW Eagle lake volcanotectonic depression are confined within the WLB. Most of the faults are high-angle normal and right normal, W-dipping, NW- to N-trending, and locally left-stepping en echelon, and 2 to 18 km long. Dip slip varies from 10 to 200 m. Strike slip across the entire zone seems impossible to determine, but probably is less than 20 km since Mid-Miocene. Many faults localize volcanic vents, though most do not appear to. Tectonic tilt of beds within fault blocks is less than 10[degree]. Fault activity and volcanism both continued at a slow rate from Mid-Miocene to Late Quaternary. The WLB in NE CA is a transitional boundary between the Sierra Nevada-Cascade arc on the southwest and the Basin and Range-Modoc Plateau on the northeast.

  1. Water Budget and Salinity of Walker Lake, western Nevada

    USGS Publications Warehouse

    Thomas, James M.

    1995-01-01

    Walker Lake is one of the rare perennial, terminal lakes in the Great Basin of the western United States. The lake is the terminus for all surface- water and ground-water flow in the Walker River Basin Hydrographic Region that is not consumed by evaporation, sublimation, or transpiration. The concentration of dissolved solids (salts) in the lake-surface altitude depend primarily on the amounts of water entering and evaporation from the lake. Because Walker Lake is a terminal sink--it has no documented surface- or ground-water outflow--dissolved solids that enter it accumulate as the lake water evaporates. Declining lake levels, owing to natural and anthropogenic processes, have resulted in most Great Basin terminal lakes being too saline to support fish. In Nevada, the only terminal lakes that contain fish are Pyramid Lake, Ruby Lake, and Walker Lake. Dissolved-solids concentration in Walker Lake increased from about 2,500 milligrams per liter in 1882 to 13,300 milli- grams per liter in July 1994 (U.S. Geological Survey analysis), as the lake-surface altitude declined from about 4,080 to 3,944 feet above sea level. This dramatic increase in dissolved-solids concentration threatens the Walker Lake ecosystem and the fish that depend on this ecosystem.

  2. Initial conditions of a simple passive-dynamic walker

    NASA Astrophysics Data System (ADS)

    Haueisen, Brooke; Hudas, Greg; Hulbert, Greg; Nebel, Kyle

    2006-05-01

    Walking robots hold great potential for the future of military robotics. Their natural agility in rough, unstructured terrain make them ideal for military applications but their power requirements do not. Passive dynamic walkers offer a potentially low-power solution. This class of legged robots utilize the natural inverted pendular dynamics that humans rely on to locomote. The most basic of these systems uses gravity as its power source and has no control system therefore its stability is heavily reliant on its initial conditions. The VICON Motion Capture System was used to record the motions of Coleman and Ruina's1 TinkertoyWalker. The initial angles and angular velocities of the various trials were extracted from the motion capture data and used as inputs to a multi-body dynamics model of the walker. The model was created to provide insight into passive-dynamic walkers and the interactions between the walker and the ground surface. Several trials were performed to quantify the stability space of the experimental walker and improve the correlation of the dynamics model to the physical robot.

  3. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946

  4. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946

  5. Superdiffusive transport by multivalent molecular walkers moving under load.

    PubMed

    Olah, Mark J; Stefanovic, Darko

    2013-06-01

    We introduce a model for translational molecular motors to demonstrate that a multivalent catalytic walker with flexible, uncoordinated legs can transform the free energy of surface-bound substrate sites into mechanical work and undergo biased, superdiffusive motion, even in opposition to an external load force. The walker in the model lacks any inherent orientation of body or track, and its legs have no chemomechanical coupling other than the passive constraint imposed by their connection to a common body. Yet, under appropriate kinetic conditions, the walker's motion is biased in the direction of unvisited sites, which allows the walker to move nearly ballistically away from the origin as long as a local supply of unmodified substrate sites is available. The multivalent random walker model is mathematically formulated as a continuous-time Markov process and is studied numerically. We use Monte Carlo simulations to generate ensemble estimates of the mean squared displacement and mean work done for this nonergodic system. Our results show that a residence time bias between visited and unvisited sites leads to superdiffusive motion over significant times and distances. This mechanism can be used to adapt any enzyme-substrate system with appropriate kinetics for use as a functional chemical implementation of a molecular motor, without the need for structural anisotropy or conformationally mediated chemomechanical coordination.

  6. Superdiffusive transport by multivalent molecular walkers moving under load

    NASA Astrophysics Data System (ADS)

    Olah, Mark J.; Stefanovic, Darko

    2013-06-01

    We introduce a model for translational molecular motors to demonstrate that a multivalent catalytic walker with flexible, uncoordinated legs can transform the free energy of surface-bound substrate sites into mechanical work and undergo biased, superdiffusive motion, even in opposition to an external load force. The walker in the model lacks any inherent orientation of body or track, and its legs have no chemomechanical coupling other than the passive constraint imposed by their connection to a common body. Yet, under appropriate kinetic conditions, the walker's motion is biased in the direction of unvisited sites, which allows the walker to move nearly ballistically away from the origin as long as a local supply of unmodified substrate sites is available. The multivalent random walker model is mathematically formulated as a continuous-time Markov process and is studied numerically. We use Monte Carlo simulations to generate ensemble estimates of the mean squared displacement and mean work done for this nonergodic system. Our results show that a residence time bias between visited and unvisited sites leads to superdiffusive motion over significant times and distances. This mechanism can be used to adapt any enzyme-substrate system with appropriate kinetics for use as a functional chemical implementation of a molecular motor, without the need for structural anisotropy or conformationally mediated chemomechanical coordination.

  7. Walker-Warburg syndrome: a report of 3 cases.

    PubMed

    Denis, D; Gambarelli, D; Luciani, A; Aymé, S; Philip, N; Saracco, J B

    1993-01-01

    Walker-Warburg syndrome is a congenital malformation syndrome of unknown etiology which is characterized by fatal neurological lesions. It was first described by Walker in 1942 as involving agyria, hydrocephalus and eye malformations. Its etiology has been discussed in all of the articles on the subject in the literature, but the majority of the authors describe it as an autosomal recessive syndrome. Ultrasonography plays a key role in detecting a cephalic anomaly by prenatal diagnosis as in our 2 cases. The aim of this article is to report 3 new cases of Walker-Warburg syndrome in two families. Knowledge of this syndrome emphasizes both the need for ultrasonographic observation and genetic counselling for families at risk.

  8. Para-Kähler-Einstein structures on Walker 4-manifolds

    NASA Astrophysics Data System (ADS)

    Iscan, Murat; Caglar, Gulnur

    2016-11-01

    A 4-dimensional Walker manifold (M4,g,D) is a semi-Riemannian manifold (M4,g) of signature (++--) (or neutral), which admits a field of null 2-plane. The goal of this paper is to study certain almost paracomplex structures φ on 4-dimensional Walker manifolds. We discuss when these structures are integrable and when the para-Kähler forms are symplectic. We show that such a Walker 4-manifold can carry a class of indefinite para-Kähler-Einstein 4-manifolds, examples of indefinite para-Kähler 4-manifolds, and also almost indefinite para-Hermitian-Einstein 4-manifold. Finally, we give a counterexample for the almost para-Hemitian version of Goldberg conjecture.

  9. Domain wall mobility, stability and Walker breakdown in magnetic nanowires

    NASA Astrophysics Data System (ADS)

    Mougin, A.; Cormier, M.; Adam, J. P.; Metaxas, P. J.; Ferré, J.

    2007-06-01

    We present an analytical calculation of the velocity of a single 180° domain wall in a magnetic structure with reduced thickness and/or lateral dimension under the combined action of an external applied magnetic field and an electrical current. As for the case of field-induced domain wall propagation in thick films, two motion regimes with different mobilities are obtained, below and far above the so-called Walker field. Additionally, for the case of current induced motion, a Walker-like current density threshold is defined. The threshold field and current density, stating the wall's internal structure stability, differ from those in thick films; both are reduced by the same geometrical demagnetising factor which accounts for the confinement. This points out the fact that the velocity dependence over an extended field/current range and the knowledge of the Walker breakdown are mandatory to draw conclusions about the phenomenological Gilbert damping parameter tuning the magnetisation dynamics.

  10. Joe Walker in pressure suit with X-1E

    NASA Technical Reports Server (NTRS)

    1958-01-01

    Joe Walker in a pressure suit beside the X-1E at the NASA High-Speed Flight Station, Edwards,California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Walker is shown in the photo wearing an early Air Force partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. Similar suits were used in such aircraft as B-47s, B-52s, F-104s, U-2s, and the X-2 and D-558-II research aircraft. Five years later, Walker reached 354,200 feet in the X-15. Similar artwork - reading 'Little Joe the II' - was applied for the record flight. These cases are two of the few times that research aircraft carried such nose art.

  11. Radial nerve palsy: a complication of walker usage.

    PubMed

    Ball, N A; Stempien, L M; Pasupuleti, D V; Wertsch, J J

    1989-03-01

    A patient with diabetic peripheral neuropathy experienced the acute onset of a proximal radial nerve palsy after prolonged use of a walker. Nerve conduction and electromyographic studies confirmed an isolated, severe neurapraxic lesion distal to branches innervating the triceps and anconeus muscles. The acute onset and severity of this lesion suggests that it was caused by mechanical compression of the radial nerve as it exits the spiral groove. Radial mononeuropathy has been reported in conjunction with muscular effort of the triceps muscle. Previous case studies and a review of the literature are discussed. Awareness of this complication in patients using walkers and wheelchairs is important for prevention and diagnosis in rehabilitation.

  12. Exact Distribution of the Maximal Height of p Vicious Walkers

    NASA Astrophysics Data System (ADS)

    Schehr, Grégory; Majumdar, Satya N.; Comtet, Alain; Randon-Furling, Julien

    2008-10-01

    Using path-integral techniques, we compute exactly the distribution of the maximal height Hp of p nonintersecting Brownian walkers over a unit time interval in one dimension, both for excursions p watermelons with a wall, and bridges p watermelons without a wall, for all integer p≥1. For large p, we show that ⟨Hp⟩˜2p (excursions) whereas ⟨Hp⟩˜p (bridges). Our exact results prove that previous numerical experiments only measured the preasymptotic behaviors and not the correct asymptotic ones. In addition, our method establishes a physical connection between vicious walkers and random matrix theory.

  13. 10. Photocopy of photograph showing the three Walker sisters ginning ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Photocopy of photograph showing the three Walker sisters ginning cotton. Misses Hettie, Martha and Louisa are from left to right. The original photograph was taken on May 21, 1936 by Edouard E. Exline and is one of five photographs in the album, 'A Sketch of Mountain Life: Great Smoky Mountains National Park', compiled by Edouard E. Exline and C.S. Grossman. The album is on file at the Great Smoky Mountains National Park; the photograph number is III-A-HSE-9642. - Walker Family Farm (General views), Gatlinburg, Sevier County, TN

  14. 78 FR 37706 - Safety Standards for Infant Walkers and Infant Swings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ... for Infant Walkers, with 22 modifications to make the standard more stringent. 75 FR 35266. ASTM... assessment bodies for testing infant walkers (75 FR 35282 (June 21, 2010)) and infant swings (78 FR 15836... COMMISSION 16 CFR Parts 1216 and 1223 Safety Standards for Infant Walkers and Infant Swings AGENCY:...

  15. Alice Walker in the Classroom: "Living by the Word." The NCTE High School Literature Series.

    ERIC Educational Resources Information Center

    Jago, Carol

    This small book is a handy guide for bringing the work of author Alice Walker into the classroom. It includes biographical information, ideas for literature circles using Walker's short stories, sample writing lessons using Walker's poems, suggestions for teaching "The Color Purple," and a wealth of resources for further investigation of Alice…

  16. Statement of Facts for 1994 City-Wide Mock Trial Competitions. Scott Walker v. Tanya Brewster.

    ERIC Educational Resources Information Center

    National Inst. for Citizen Education in the Law, Washington, DC.

    Prepared by the District of Columbia Street Law Project for its 23rd annual city-wide mock trial competition, this instructional handout provides the material for a mock civil trial over an accidental shooting. Thirteen-year-old T. J. Walker, Scott Walker's son from a previous marriage, visited the home of 5-year-old Jesse Walker with a pistol…

  17. Hazard Patterns and Injury Prevention with Infant Walkers and Strollers.

    ERIC Educational Resources Information Center

    Wishon, Phillip M.; And Others

    Mindful of the potential hazards associated with products intended for young children, this article examines pediatric accidents involving strollers and walkers. According to the latest figures available from the National Electronic Injury Surveillance System of the United States (NEISS), more than 11,800 stroller injuries in 1987 were serious…

  18. Set the Signals at Green! The William Walker Oration.

    ERIC Educational Resources Information Center

    Chapman, Judith D.

    1995-01-01

    Acknowledges the late Professor Emeritus William G. Walker's contribution to educational administration. Describes major advances in epistemological perspectives and metatheoretical frameworks underlying recent educational administration research in Australia. A progressive research agenda should focus on preserving systems, empowering schools,…

  19. Alice Walker's Politics or the Politics of "The Color Purple."

    ERIC Educational Resources Information Center

    Hamilton, Cynthia

    1988-01-01

    Alice Walker's "The Color Purple" portrays Black women's oppression as the result of patriarchy, and proposes the acceptance of middle-class values--home ownership and entrepreneurship--as the solution to exploitation. She relies on stereotypes to characterize Black men and women, and depicts an ideology of submission. (BJV)

  20. A stochastic DNA walker that traverses a microparticle surface

    PubMed Central

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2015-01-01

    Molecular machines have previously been designed that are propelled by DNAzymes1–3, protein enzymes4–6 and strand-displacement7–9. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridisation to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridisation reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilisation of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays10,11. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations12,13 that have been shown to lead to pattern formation14–17. PMID:26524397

  1. Aerial view, view north with Walkers Mill left of the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Aerial view, view north with Walkers Mill left of the creek, Henry Clay village right of creek, Tyler-Mcconnell Bridge in middleground, and Hagley area beyond the bridge - Charles I. Du Pont House, 162 Main Street, Wilmington, New Castle County, DE

  2. 75 FR 51178 - Safety Standard for Infant Walkers; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

    ..., 2010 (75 FR 35266). The document established a standard for infant walkers. The Commission is... INFORMATION: In the Federal Register of June 21, 2010 (75 FR 35266), the Commission published a final rule... section refers, incorrectly, to ``Plane A'' (see 75 FR at 35275 (col. 3) through 35276 (col. 2))....

  3. Walker Calhoun: Master of His Art, Keeper of Traditions.

    ERIC Educational Resources Information Center

    Hoffman, Carl

    1993-01-01

    During the 1920s, Walker Calhoun learned traditional songs and dances from his uncle, Will West Long, spiritual leader of the Big Cove Cherokees. Nine years ago, Calhoun began teaching them to his grandchildren and other young people. Calhoun has received numerous honors for his work to preserve Cherokee culture. (LP)

  4. A stochastic DNA walker that traverses a microparticle surface.

    PubMed

    Jung, C; Allen, P B; Ellington, A D

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation. PMID:26524397

  5. 11. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard and Gill, Architects October 28, 1904 BLUEPRINT OF ORIGINAL DRAWING OF NORTH ELEVATION From the Collection of the San Diego Historical Society - George W. Marston House, 3525 Seventh Avenue, San Diego, San Diego County, CA

  6. 12. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard and Gill, Architects September 23, 1904 (Revised October 28, 1904) BLUEPRINT OF ORIGINAL DRAWING OF EAST ELEVATION From the Collection of the San Diego Historical Society - George W. Marston House, 3525 Seventh Avenue, San Diego, San Diego County, CA

  7. 10. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard and Gill, Architects September 21, 1904 (Revised October 28, 1904) BLUEPRINT OF ORIGINAL DRAWING OF WEST ELEVATION From the Collection of the San Diego Historical Society - George W. Marston House, 3525 Seventh Avenue, San Diego, San Diego County, CA

  8. Behavior of Friedmann-Lemaître-Robertson-Walker Singularities

    NASA Astrophysics Data System (ADS)

    Fernández-Jambrina, L.

    2016-08-01

    In Stoica (Int. J. Theor. Phys. 55, 71-80, 2016) a regularization procedure is suggested for regularizing Big Bang singularities in Friedmann-Lemaître-Robertson-Walker (FLRW) spacetimes. We argue that this procedure is only appliable to one case of Big Bang singularities and does not affect other types of singularities.

  9. Larval description of Copitarsia incommoda (Walker) (Lepidoptera: Noctuidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The last-instar larva of Copitarsia incommoda (Walker) is described for the first time. Specimens in this study were reared from quinoa (Chenopodium quinoa Willd., Chenopodiaceae), Bolivia, La Paz, 4 km S Viacha, Quipaquipani, 3880 m. The larva of Copitarsia incommoda is compared with larvae of Copi...

  10. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ....C. 552(a) and 1 CFR part 51. You may obtain a copy from ASTM International, 100 Bar Harbor Drive, P...(s) to the edge of the test platform, ER21JN10.003 Where Vf = Maximum velocity of walker at edge of platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI dummy Wwalker = Weight of...

  11. Quantum Analysis of k=-1 Robertson-Walker Universe

    NASA Astrophysics Data System (ADS)

    Dariescu, Ciprian; Dariescu, Marina-Aura

    2015-11-01

    The (k=-1)-Robertson-Walker spacetime is under investigation. With the derived Hamilton operator, we are solving the Wheeler-De Witt Equation and its Schrödinger-like extension, for physically important forms of the effective potential. The closed form solutions, expressed in terms of Heun's functions, allow us to comment on the occurrence of Universe from highly probable quantum states.

  12. A new species of Culcua Walker (Diptera: Stratiomyidae) from Vietnam

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new species of Culcua Walker (Diptera: Stratiomyidae), C. lingafelteri Woodley, new species, is described from northern Vietnam. It is diagnosed relative to other species using the recent revision of the genus by Rozkošný and Kozánek (2007). This is the first species of Culcua reported from Viet...

  13. Roy Lee Walker Elementary School, McKinney ISD. [Videotape].

    ERIC Educational Resources Information Center

    SHW Group, Inc., Dallas, TX.

    This 7:50-minute videotape describes the architectural design and structure of the Roy Lee Walker Elementary School, illustrating why the school is considered the most energy efficient and environmentally sound school ever built. The videotape highlights the sustainable, award-winning design features such as the innovative use of daylight to…

  14. INTERIOR VIEW WITH STIFF LEG LADLE CRANE OPERATOR, LUKE WALKER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW WITH STIFF LEG LADLE CRANE OPERATOR, LUKE WALKER, POURING OFF SLAG FROM LADLE AS SKIMMER, BRUCE ELLIOTT, RAKES THE SLAG FROM THE MOLTEN METAL. - American Cast Iron Pipe Company, Mixer Building, 1501 Thirty-first Avenue North, Birmingham, Jefferson County, AL

  15. 75 FR 38833 - Walker River Basin Acquisition Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-06

    ... by the recipient to acquire from willing sellers land, water appurtenant to the land, and related interests in the Walker River Basin, Nevada. Acquired water rights would be transferred to provide water for... 156 feet. The decrease has resulted in extremely poor water quality and deteriorated lake ecology....

  16. 9. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Historic American Buildings Survey Mr. Walker, Draftsman of Hebbard and Gill, Architects September 21, 1904 (Revised October 21, 1904) BLUEPRINT OF ORIGINAL DRAWING OF SOUTH ELEVATION From the Collection of the San Diego Historical Society - George W. Marston House, 3525 Seventh Avenue, San Diego, San Diego County, CA

  17. STS-69 Mission Commander David M. Walker in white room

    NASA Technical Reports Server (NTRS)

    1995-01-01

    STS-69 Mission Commander David M. Walker chats with white room closeout crew members Bob Saulnier (left), Regulo Villalobos and closeout crew leader Travis Thompson prior to entering the flight deck of the Space Shuttle Endeavour at Launch Pad 39A.

  18. Bathymetry of Walker Lake, West-Central Nevada

    USGS Publications Warehouse

    Lopes, Thomas J.; Smith, J. LaRue

    2007-01-01

    Walker Lake lies within a topographically closed basin in west-central Nevada and is the terminus of the Walker River. Much of the streamflow in the Walker River is diverted for irrigation, which has contributed to a decline in lake-surface altitude of about 150 feet and an increase in dissolved solids from 2,500 to 16,000 milligrams per liter in Walker Lake since 1882. The increase in salinity threatens the fresh-water ecosystem and survival of the Lahontan cutthroat trout, a species listed as threatened under the Endangered Species Act. Accurately determining the bathymetry and relations between lake-surface altitude, surface area, and storage volume are part of a study to improve the water budget for Walker Lake. This report describes the updated bathymetry of Walker Lake, a comparison of results from this study and a study by Rush in 1970, and an estimate of the 1882 lake-surface altitude. Bathymetry was measured using a single-beam echosounder coupled to a differentially-corrected global positioning system. Lake depth was subtracted from the lake-surface altitude to calculate the altitude of the lake bottom. A Lidar (light detection and ranging) survey and high resolution aerial imagery were used to create digital elevation models around Walker Lake. The altitude of the lake bottom and digital elevation models were merged together to create a single map showing land-surface altitude contours delineating areas that are currently or that were submerged by Walker Lake. Surface area and storage volume for lake-surface altitudes of 3,851.5-4,120 feet were calculated with 3-D surface-analysis software. Walker Lake is oval shaped with a north-south trending long axis. On June 28, 2005, the lake-surface altitude was 3,935.6 feet, maximum depth was 86.3 feet, and the surface area was 32,190 acres. The minimum altitude of the lake bottom from discrete point depths is 3,849.3 feet near the center of Walker Lake. The lake bottom is remarkably smooth except for mounds near

  19. Finding the Right Formula: Edwin H. Walker Jr

    ERIC Educational Resources Information Center

    Keels, Crystal L.

    2005-01-01

    Edwin H. Walker Jr earned his doctorate in chemistry at age 27 and has barely looked back. With 13 publications under his belt before coming out of graduate school, he has also given more than 20 poster presentations in national venues, most recently at the American Chemical Society. He can also include securing a half-million-dollar National…

  20. 78 FR 48301 - Establishment of Class E Airspace; Walker, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ..., area, creating controlled airspace at Walker Municipal Airport (78 FR 25234) Docket No. FAA-2013-0266... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR...

  1. Mary Edwards Walker: the soul ahead of her time.

    PubMed

    Rehman, Atiq; Rahman, Naba G; Harris, Sharon M; Cheema, Faisal H

    2015-02-01

    Mary Edwards Walker was a gallant woman who stood for women's rights, embodied the true American spirit, and served the Union Army in the Civil War as a surgeon. She later became the first and only woman in United States history to be awarded the Congressional Medal of Honor. PMID:25535874

  2. A stochastic DNA walker that traverses a microparticle surface

    NASA Astrophysics Data System (ADS)

    Jung, C.; Allen, P. B.; Ellington, A. D.

    2016-02-01

    Molecular machines have previously been designed that are propelled by DNAzymes, protein enzymes and strand displacement. These engineered machines typically move along precisely defined one- and two-dimensional tracks. Here, we report a DNA walker that uses hybridization to drive walking on DNA-coated microparticle surfaces. Through purely DNA:DNA hybridization reactions, the nanoscale movements of the walker can lead to the generation of a single-stranded product and the subsequent immobilization of fluorescent labels on the microparticle surface. This suggests that the system could be of use in analytical and diagnostic applications, similar to how strand exchange reactions in solution have been used for transducing and quantifying signals from isothermal molecular amplification assays. The walking behaviour is robust and the walker can take more than 30 continuous steps. The traversal of an unprogrammed, inhomogeneous surface is also due entirely to autonomous decisions made by the walker, behaviour analogous to amorphous chemical reaction network computations, which have been shown to lead to pattern formation.

  3. A guideline for the design of a four-wheeled walker.

    PubMed

    Finkel, J; Fernie, G; Cleghorn, W

    1997-01-01

    More people use assistive technology devices to compensate for mobility impairments than for any other general type of impairment. Increasing numbers of people with mobility or balance problems use walkers with four wheels. Four-wheeled walkers are often outfitted with seats to make it possible to travel longer distances with intermediate resting periods. The dangers of sitting on a parked walker are well known. Many physiotherapists tell walker users to park the walker against a wall to prevent injury in case the user forgets to apply the brakes or the brakes fail. To design a safer walker that can be used for sitting, the demands placed on it must be measured. With these data, three modes of walker instability must be considered: first, the brakes may hold but the wheels may slide along the ground; second, the entire walker may tip over; and third, the brakes may fail to hold the wheels in place, and they may begin to roll. Mathematical models can be constructed to simulate how different walker designs will perform. By this process, design improvements can be made for existing walkers, and future walker designs can also be proposed.

  4. Friedman—Robertson—Walker Models with Late-Time Acceleration

    NASA Astrophysics Data System (ADS)

    Abdussattar; Prajapati, S. R.

    2011-02-01

    In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman—Robertson—Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.

  5. Stability of a Robertson-Walker universe against stochastic perturbations

    NASA Astrophysics Data System (ADS)

    Briozzo, C. B.; Budde, C. E.; Caceres, M. O.; Lamberti, P. W.

    1988-06-01

    The Einstein-Langevin equations for a Robertson-Walker universe in which a small stochastic perturbation is introduced in the deterministic equations of motion for the radius of the universe are analysed. We solve the associated nonlinear Fokker-Planck equation in the small noise limit using the Ω expansion and find that the cosmological constant plays an essential role in the long time stability of the model. Fellowship holder at CONICET.

  6. The Congo Basin Walker circulation: dynamics and connections to precipitation

    NASA Astrophysics Data System (ADS)

    Cook, Kerry H.; Vizy, Edward K.

    2016-08-01

    The existence, seasonality, and variability of a Congo Basin Walker circulation are investigated in reanalyses, and connections with rainfall are explored. A zonal overturning circulation along the equator connects rising motion in the Congo Basin and sinking in the eastern Atlantic during June through October. This timing is out of phase with precipitation over equatorial Africa, which greatest during spring and fall, and does not correlate with the seasonality of land temperatures. Rather, the zonally-overturning circulation only occurs when the Atlantic cold tongue has formed. Although the cold tongue formation is essential for setting up the Congo Basin Walker circulation, variations in equatorial eastern Atlantic sea surface temperatures are not associated with interannual variability in the strength of the circulation. When cold tongue SSTs are anomalously cool (warm), evaporation from the ocean surface is reduced (enhanced) and the westerly flow advects less (more) moisture into the base of the Congo Basin Walker circulation. This reduces (increases) the release of latent heat in the upbranch and weakens (strengthens) the Walker circulation. This process dominates the pure dry dynamical response to enhanced land/sea temperature differences, which has an opposite sign. A positive correlation connects low-level vertical velocity in the Congo basin with low-level vertical velocity and precipitation over West Africa. A wave response to anomalous vertical velocity in the Congo Basin in several reanalyses suggests a teleconnection into West Africa such that an anomalously strong (weak) upbranch is associated with anomalously strong (weak) rainfall over the Guinean coast and southern Sahel.

  7. 1. EXTERIOR VIEW OF ELM CITY PLANT (A. FRANCIS WALKER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. EXTERIOR VIEW OF ELM CITY PLANT (A. FRANCIS WALKER, 1905-07) FROM SECOND AVENUE ON OPPOSITE SIDE OF ENTRANCE. THIS STRUCTURE WAS ORIGINALLY BUILT AS THE ELM CITY COTTON MILL OF CALLAWAY MILLS. NOTE RESERVOIR IN FOREGROUND. THIS PHOTOGRAPH IS THE LEFT SIDE OF A PANORAMA VIEW THAT INCLUDES HAER Nos. GA-128-2 AND GA-128-3. - Elm City Cotton Mill, 1000 Elm Street, La Grange, Troup County, GA

  8. Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models

    USGS Publications Warehouse

    Allander, Kip K.; Niswonger, Richard G.; Jeton, Anne E.

    2014-01-01

    The effects of fallowing of Walker River Indian Irrigation Project fields from 2007 to 2010 on Walker Lake inflow, level, and dissolved solids were evaluated. Fallowing resulted in a near doubling of Walker River inflow to Walker Lake during this period, an increase in Walker Lake level of about 1.4 feet, and a decrease in dissolved-solids concentration of about 540 mg/L.

  9. Anomalous Walker circulations associated with two flavors of the Indian Ocean Dipole

    NASA Astrophysics Data System (ADS)

    Tozuka, Tomoki; Endo, Satoru; Yamagata, Toshio

    2016-05-01

    The Walker circulation is the key component of the atmospheric zonal circulation in the tropics. In this study, it is shown that anomalous Walker circulations associated with two types of the Indian Ocean Dipole (IOD) are remarkably different. During a positive canonical IOD with negative (positive) sea surface temperature (SST) anomalies in the eastern (central to western) tropical Indian Ocean, a single-cell anomalous Walker circulation forms over the Indian Ocean. On the other hand, a double-cell anomalous Walker circulation with a rising branch in the central Indian Ocean is formed during a positive IOD Modoki, which is associated with positive (negative) SST anomalies over the central (eastern and western) tropical Indian Ocean. The above anomalous Walker circulations are found to develop as part of positive ocean-atmosphere feedback. Furthermore, the above difference in the anomalous Walker circulation may affect the biennial tendency of the IOD.

  10. Efficient bipedal robots based on passive-dynamic walkers.

    PubMed

    Collins, Steve; Ruina, Andy; Tedrake, Russ; Wisse, Martijn

    2005-02-18

    Passive-dynamic walkers are simple mechanical devices, composed of solid parts connected by joints, that walk stably down a slope. They have no motors or controllers, yet can have remarkably humanlike motions. This suggests that these machines are useful models of human locomotion; however, they cannot walk on level ground. Here we present three robots based on passive-dynamics, with small active power sources substituted for gravity, which can walk on level ground. These robots use less control and less energy than other powered robots, yet walk more naturally, further suggesting the importance of passive-dynamics in human locomotion.

  11. Irreversible aggregation of flexible chainlike walkers without adherence.

    PubMed

    Mashiko, Takashi

    2008-07-01

    The flexible chainlike walker (FCW) model is proposed as a minimal model of a deformable moving object and as an extension of the regular random-walk model. The many-body system of FCWs is studied by numerical simulations on a square lattice. It is shown that FCWs aggregate spontaneously and irreversibly where no adherence is assumed, in contrast to the established aggregation models, where adherence is indispensable for their occurrence and irreversibility. This type of aggregation is enabled by and demonstrates the significance of the deformability of moving objects.

  12. Science to Sustain Terminal Lakes: The Walker River Basin Study

    USGS Publications Warehouse

    ,

    2005-01-01

    Section 2507 of Public Law 107-171 (2002 Farm Bill) provided $200,000,000 to be used by the Secretary of the Interior, acting through the Commissioner of Reclamation, to provide water to at-risk natural desert terminal lakes. This bill was later amended under Public Law 108-7, Section 207 to include language 'Restoration of fish, wildlife, and associated habitats in watersheds of certain lakes'. The amendment specified that only Pyramid, Summit, and Walker Lakes in the State of Nevada were to be considered under Section 2507, Public Law 107-171.

  13. Spatial and Lorentzian surfaces in Robertson-Walker space times

    NASA Astrophysics Data System (ADS)

    Chen, Bang-Yen; Van der Veken, Joeri

    2007-07-01

    Let L14(f,c)=(I×fS,gfc) be a Robertson-Walker space time which does not contain any open subset of constant curvature. In this paper, we provide a general study of nondegenerate surfaces in L14(f,c). First, we prove the nonexistence of marginally trapped surfaces with positive relative nullity. Then, we classify totally geodesic submanifolds. Finally, we classify the family of surfaces with parallel second fundamental form and the family of totally umbilical surfaces with parallel mean curvature vector.

  14. Pilot Joe Walker with the X-1E

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the nose section of the X-1E with pilot Joe Walker suited for a flight at the NASA High-Speed Flight Station, Edwards, California. The dice and Little Joe are prominently displayed under the cockpit area. NASA employees and the crew chief of the plane worked long hours preparing a craft for flight. A break from the tedious task was a welcome reprieve at times; hence the private joke between a crew and their pilot evolved. If you know the craps game you've figured it out! (Little Joe is a dice player's slang term for two deuces.)

  15. Number of distinct sites visited by a subdiffusive random walker.

    PubMed

    Yuste, Santos Bravo; Klafter, J; Lindenberg, Katja

    2008-03-01

    The asymptotic mean number of distinct sites visited by a subdiffusive continuous-time random walker in two dimensions seems not to have been explicitly calculated anywhere in the literature. This number has been calculated for other dimensions for only one specific asymptotic behavior of the waiting time distribution between steps. We present an explicit derivation for two cases in all integer dimensions so as to formally complete a tableau of results. In this tableau we include the dominant as well as subdominant contributions in all integer dimensions. Other quantities that can be calculated from the mean number of distinct sites visited are also discussed.

  16. Noncommutative corrections to the Robertson-Walker metric

    SciTech Connect

    Fabi, S.; Harms, B.; Stern, A.

    2008-09-15

    Upon applying Chamseddine's noncommutative deformation of gravity, we obtain the leading order noncommutative corrections to the Robertson-Walker metric tensor. We get an isotropic inhomogeneous metric tensor for a certain choice of the noncommutativity parameters. Moreover, the singularity of the commutative metric at t=0 is replaced by a more involved space-time structure in the noncommutative theory. In a toy model we construct a scenario where there is no singularity at t=0 at leading order in the noncommutativity parameter. Although singularities may still be present for nonzero t, they need not be the source of all timelike geodesics and the result resembles a bouncing cosmology.

  17. Optimal recruitment strategies for groups of interacting walkers with leaders

    NASA Astrophysics Data System (ADS)

    Martínez-García, Ricardo; López, Cristóbal; Vazquez, Federico

    2015-02-01

    We introduce a model of interacting random walkers on a finite one-dimensional chain with absorbing boundaries or targets at the ends. Walkers are of two types: informed particles that move ballistically towards a given target and diffusing uninformed particles that are biased towards close informed individuals. This model mimics the dynamics of hierarchical groups of animals, where an informed individual tries to persuade and lead the movement of its conspecifics. We characterize the success of this persuasion by the first-passage probability of the uninformed particle to the target, and we interpret the speed of the informed particle as a strategic parameter that the particle can tune to maximize its success. We find that the success probability is nonmonotonic, reaching its maximum at an intermediate speed whose value increases with the diffusing rate of the uninformed particle. When two different groups of informed leaders traveling in opposite directions compete, usually the largest group is the most successful. However, the minority can reverse this situation and become the most probable winner by following two different strategies: increasing its attraction strength or adjusting its speed to an optimal value relative to the majority's speed.

  18. Monocoque structure for the SKITTER three-legged walker

    NASA Technical Reports Server (NTRS)

    Bansek, Robert N.; Booth, Andrew J.; Daneman, Steven A.; Dresser, James A.; Haney, Todd G.; Johnson, Gregory R.; Lindzen, Eric C.; Montgomery, Robert C.; Warren, Andrew L.

    1988-01-01

    The SKITTER 2 design is a monocoque version of the proposed lunar three-legged walker. By the definition of monocoque, the body and legs are a shell with no internal ribbing or supports added for absorbing stresses. The purpose of the monocoque is to encase the elements used for power transmission, power supply, and control of the motion. The material for the structure is a vinyl ester resin, Derakane 8084. This material is easily formable and locally obtainable. The body consists of a hexagonally shaped cylinder with truncated hexagonal pyramids on the top and botton. The legs are eight inch diameter cylinders. The legs are comprised of a tibia section and a femur section. The SKITTER 2 is powered by six actuators which provide linear forces that are transformed into rotary torques by a series of chains and sprockets. The joints connect the femur to the body and the tibia to the femur. Surrounding the joints are flexible rubber hoses that fully encase the chains and sprockets. The SKITTER 2 is capable of walking upside down, righting itself after being overturned, and has the ability to perform in many environments. Applications for this walker include lunar transport or drilling, undersea exploration, and operation in severe surroundings such as arctic temperatures or high radiation.

  19. FreeWalker: a smart insole for longitudinal gait analysis.

    PubMed

    Wang, Baitong; Rajput, Kuldeep Singh; Tam, Wing-Kin; Tung, Anthony K H; Yang, Zhi

    2015-08-01

    Gait analysis is an important diagnostic measure to investigate the pattern of walking. Traditional gait analysis is generally carried out in a gait lab, with equipped force and body tracking sensors, which needs a trained medical professional to interpret the results. This procedure is tedious, expensive, and unreliable and makes it difficult to track the progress across multiple visits. In this paper, we present a smart insole called FreeWalker, which provides quantitative gait analysis outside the confinement of traditional lab, at low- cost. The insole consists of eight pressure sensors and two motion tracking sensors, i.e. 3-axis accelerometer and 3-axis gyroscope. This enables measurement of under-foot pressure distribution and motion sequences in real-time. The insole is enabled with onboard SD card as well as wireless data transmission, which help in continuous gait-cycle analysis. The data is then sent to a gateway, for analysis and interpretation of data, using a user interface where gait features are graphically displayed. We also present validation result of a subject's left foot, who was asked to perform a specific task. Experiment results show that we could achieve a data-sampling rate of over 1 KHz, transmitting data up to a distance of 20 meter and maintain a battery life of around 24 hours. Taking advantage of these features, FreeWalker can be used in various applications, like medical diagnosis, rehabilitation, sports and entertainment. PMID:26737102

  20. Quantum centipedes: collective dynamics of interacting quantum walkers

    NASA Astrophysics Data System (ADS)

    Krapivsky, P. L.; Luck, J. M.; Mallick, K.

    2016-08-01

    We consider the quantum centipede made of N fermionic quantum walkers on the one-dimensional lattice interacting by means of the simplest of all hard-bound constraints: the distance between two consecutive fermions is either one or two lattice spacings. This composite quantum walker spreads ballistically, just as the simple quantum walk. However, because of the interactions between the internal degrees of freedom, the distribution of its center-of-mass velocity displays numerous ballistic fronts in the long-time limit, corresponding to singularities in the empirical velocity distribution. The spectrum of the centipede and the corresponding group velocities are analyzed by direct means for the first few values of N. Some analytical results are obtained for arbitrary N by exploiting an exact mapping of the problem onto a free-fermion system. We thus derive the maximal velocity describing the ballistic spreading of the two extremal fronts of the centipede wavefunction, including its non-trivial value in the large-N limit.

  1. FreeWalker: a smart insole for longitudinal gait analysis.

    PubMed

    Wang, Baitong; Rajput, Kuldeep Singh; Tam, Wing-Kin; Tung, Anthony K H; Yang, Zhi

    2015-08-01

    Gait analysis is an important diagnostic measure to investigate the pattern of walking. Traditional gait analysis is generally carried out in a gait lab, with equipped force and body tracking sensors, which needs a trained medical professional to interpret the results. This procedure is tedious, expensive, and unreliable and makes it difficult to track the progress across multiple visits. In this paper, we present a smart insole called FreeWalker, which provides quantitative gait analysis outside the confinement of traditional lab, at low- cost. The insole consists of eight pressure sensors and two motion tracking sensors, i.e. 3-axis accelerometer and 3-axis gyroscope. This enables measurement of under-foot pressure distribution and motion sequences in real-time. The insole is enabled with onboard SD card as well as wireless data transmission, which help in continuous gait-cycle analysis. The data is then sent to a gateway, for analysis and interpretation of data, using a user interface where gait features are graphically displayed. We also present validation result of a subject's left foot, who was asked to perform a specific task. Experiment results show that we could achieve a data-sampling rate of over 1 KHz, transmitting data up to a distance of 20 meter and maintain a battery life of around 24 hours. Taking advantage of these features, FreeWalker can be used in various applications, like medical diagnosis, rehabilitation, sports and entertainment.

  2. [Aicardi syndrome with Dandy-Walker type malformation].

    PubMed

    Laguado-Herrera, Yuly V; Manrique-Hernández, Edgar F; Peñaloza-Mantilla, Camilo A; Quintero-Gómez, David A; Contreras-García, Gustavo A; Sandoval-Martínez, Diana K

    2015-07-16

    Introduccion. El sindrome de Aicardi (OMIM 304050) fue descrito en 1965. Su triada clasica esta compuesta por espasmos infantiles, agenesia parcial o total del cuerpo calloso y alteraciones oculares, como lagunas coriorretinianas. Se postula un mecanismo de herencia ligado a X dominante. Caso clinico. Niña nacida a termino, sin antecedentes familiares patologicos ni consanguinidad parental, con diagnostico prenatal de malformacion tipo Dandy-Walker, quien presento episodios convulsivos, coloboma del nervio optico, bloque vertebral toracico con presencia de escoliosis, ecografia transfontanelar con agenesia del cuerpo calloso y cariotipo 46,XX. Se diagnostico de sindrome de Aicardi y fallecio con mes y medio de edad. En la autopsia se evidencio hidrocefalia supratentorial con presencia de papiloma de los plexos coroideos, quiste en la fosa posterior (cuarto ventriculo), hipoplasia del vermis cerebeloso, agenesia del hemisferio del cuerpo calloso y cerebeloso izquierdo, rasgos faciales caracteristicos del sindrome, paladar ojival, pectus excavatum, escoliosis, quiste paraovarico y hepatomegalia. Conclusiones. Pocos casos han descrito la asociacion de la patologia y la presencia de malformacion de Dandy-Walker. Se comunica un nuevo caso con esta asociacion, teniendo en cuenta que las alteraciones relacionadas, principalmente agenesia o hipoplasia del cuerpo calloso, sugieren que tiene un componente genetico de base. El estudio de busqueda de la etiologia de centrarse en evaluar aquellos genes que tengan relacion con el neurodesarrollo y su activacion en la etapa de organogenia. El diagnostico definitivo establece el pronostico, manejo y asesoria genetica a la familia.

  3. Dissemination of Walker 256 carcinoma cells to rat skeletal muscle

    SciTech Connect

    Ueoka, H.; Hayashi, K.; Namba, T.; Grob, D.

    1986-03-05

    After injection of 10/sup 6/ Walker 256 carcinoma cells labelled with /sup 125/I-5-iodo-2'-deoxyuridine into the tail vein, peak concentration in skeletal muscle was 46 cells/g at 60 minutes, which was lower than 169202, 1665, 555, 198 and 133 cells/g, respectively, at 30 or 60 minutes in lung, liver, spleen, kidney and heart. Because skeletal muscle constitutes 37.4% of body weight, the total number of tumor cells was 2323 cells, which was much greater than in spleen, kidney and heart with 238, 271, and 85 cells, respectively, and only less than in lung and liver, at 222857 and 11700 cells, respectively. The total number in skeletal muscle became greater than in liver at 4 hours and than in lung at 24 hours. Ten minutes after injection of 7.5 x 10/sup 6/ Walker 256 carcinoma cells into the abdominal aorta of rats, a mean of 31 colony-forming cells were recovered from the gastrocnemius, while 106 cells were recovered from the lung after injection into the tail vein. These results indicate that a large number of viable tumor cells can be arrested in skeletal muscle through circulation. The rare remote metastasis of malignancies into skeletal muscle despite constantly circulating tumor cells does not appear to be due to poor dissemination of tumor cells into muscle but due to unhospitable environment of skeletal muscle.

  4. Optimal recruitment strategies for groups of interacting walkers with leaders.

    PubMed

    Martínez-García, Ricardo; López, Cristóbal; Vazquez, Federico

    2015-02-01

    We introduce a model of interacting random walkers on a finite one-dimensional chain with absorbing boundaries or targets at the ends. Walkers are of two types: informed particles that move ballistically towards a given target and diffusing uninformed particles that are biased towards close informed individuals. This model mimics the dynamics of hierarchical groups of animals, where an informed individual tries to persuade and lead the movement of its conspecifics. We characterize the success of this persuasion by the first-passage probability of the uninformed particle to the target, and we interpret the speed of the informed particle as a strategic parameter that the particle can tune to maximize its success. We find that the success probability is nonmonotonic, reaching its maximum at an intermediate speed whose value increases with the diffusing rate of the uninformed particle. When two different groups of informed leaders traveling in opposite directions compete, usually the largest group is the most successful. However, the minority can reverse this situation and become the most probable winner by following two different strategies: increasing its attraction strength or adjusting its speed to an optimal value relative to the majority's speed.

  5. Evapotranspiration from the Lower Walker River Basin, West-Central Nevada, Water Years 2005-07

    USGS Publications Warehouse

    Allander, Kip K.; Smith, J. LaRue; Johnson, Michael J.

    2009-01-01

    Evapotranspiration is the ultimate path of outflow of nearly all water from the Lower Walker River basin. Walker Lake is the terminus of the topographically closed Walker River basin, and the lake level has been declining at an average rate of about 1.6 feet per year (ft/yr) since 1917. As a result of the declining lake level, dissolved-solids concentrations are increasingly threatening the fishery and ecosystem health of the lake. Uncertainties in the water budget components of the Lower Walker River basin led the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, to undertake an investigation to refine estimates of the water budget. Evapotranspiration from the Lower Walker River basin represents a major component of this water budget. The specific objectives of this report are to provide estimates of total and net evapotranspiration for water years 2005-07 for areas in the Lower Walker River basin in which annual evapotranspiration exceeds annual precipitation, and to summarize these results for areas of similar vegetation and soil characteristics, hydrographic subareas, and Walker Lake and Weber Reservoir. The three hydrographic subareas include the area along Walker River north of Walker Lake, the area of and adjacent to Walker Lake, and the area south of Walker Lake. Areas of annual evapotranspiration exceeding annual precipitation were identified and mapped in the field and were further delineated using remote-sensing analysis. These areas were classified into 10 evapotranspiration units. A network of 11 evapotranspiration stations was operated in natural and agricultural vegetation and on Walker Lake. Measured evapotranspiration rates ranged from 0.5 ft/yr at a sparsely vegetated desert shrub site to 5.0 ft/yr from Walker Lake. The greatest evapotranspiration rate on land was 4.1 ft/yr at an irrigated alfalfa field, and the greatest rate for natural vegetation was 3.9 ft/yr in a riparian community along Walker River. At an

  6. Two American Entrepreneurs: Madame C. J. Walker and J. C. Penney. Teaching with Historic Places.

    ERIC Educational Resources Information Center

    Koman, Rita

    2000-01-01

    This lesson is based on the National Historic Landmark files, "Madame C. J. Walker Building" and "J. C. Penney Historic District," as well as other relevant sources. The lesson first discusses the Indianapolis (Indiana) site of Madame Walker's cosmetics business. The building is a 4-story brick structure completed in 1927. Another building built…

  7. Folklore in the Fiction of Alice Walker: A Perpetuation of Historical and Literary Traditions

    ERIC Educational Resources Information Center

    Harris, Trudier

    1977-01-01

    Discusses the fiction of Alice Walker, showing that, in employing folklore for the purposes of defining characters, illustrating relationships among them, and developing plot, Alice Walker comments on the racial situation in the United States, often chastising her black characters for their attitudes toward themselves. (JM)

  8. n-dimensional generalizations of the Friedmann Robertson Walker cosmology

    NASA Astrophysics Data System (ADS)

    Garcia, Alberto A.; Carlip, Steve

    2007-02-01

    Within the n-dimensional spatially flat Friedmann Robertson Walker cosmology, determined for a single scalar field minimally coupled to gravity, we derive the n-dimensional Lucchin Mataresse (LM), Barrow Burd Lancaster Madsen (BBLM), and Barrow Saich (BS) cosmological solutions. No matter the dimensions one is dealing with, the potentials follow patterns similar to those ones of the corresponding standard 4-dimensional case; the self interacting potential for the n-LM inflationary model exhibits an exponential slow roll behavior as function of the scalar field, the potential of the n-BBLM model presents a Mexican-hat shape, while the potential for the n-BS cosmology, allowing for the simultaneous presence of a matter perfect fluid and a scalar field, follows a squared cosecant hyperbolic pattern.

  9. Null hypersurfaces in generalized Robertson-Walker spacetimes

    NASA Astrophysics Data System (ADS)

    Navarro, Matias; Palmas, Oscar; Solis, Didier A.

    2016-08-01

    We study the geometry of null hypersurfaces M in generalized Robertson-Walker spacetimes. First we characterize such null hypersurfaces as graphs of generalized eikonal functions over the fiber and use this characterization to show that such hypersurfaces are parallel if and only if their fibers are also parallel. We further use this technique to construct several examples of null hypersurfaces in both de Sitter and anti de Sitter spaces. Then we characterize all the totally umbilical null hypersurfaces M in a Lorentzian space form (viewed as a quadric in a semi-Euclidean ambient space) as intersections of the space form with a hyperplane. Finally we study the totally umbilical spacelike hypersurfaces of null hypersurfaces in space forms and characterize them as planar sections of M.

  10. Test battery with the human cell line activation test, direct peptide reactivity assay and DEREK based on a 139 chemical data set for predicting skin sensitizing potential and potency of chemicals.

    PubMed

    Takenouchi, Osamu; Fukui, Shiho; Okamoto, Kenji; Kurotani, Satoru; Imai, Noriyasu; Fujishiro, Miyuki; Kyotani, Daiki; Kato, Yoshinao; Kasahara, Toshihiko; Fujita, Masaharu; Toyoda, Akemi; Sekiya, Daisuke; Watanabe, Shinichi; Seto, Hirokazu; Hirota, Morihiko; Ashikaga, Takao; Miyazawa, Masaaki

    2015-11-01

    To develop a testing strategy incorporating the human cell line activation test (h-CLAT), direct peptide reactivity assay (DPRA) and DEREK, we created an expanded data set of 139 chemicals (102 sensitizers and 37 non-sensitizers) by combining the existing data set of 101 chemicals through the collaborative projects of Japan Cosmetic Industry Association. Of the additional 38 chemicals, 15 chemicals with relatively low water solubility (log Kow > 3.5) were selected to clarify the limitation of testing strategies regarding the lipophilic chemicals. Predictivities of the h-CLAT, DPRA and DEREK, and the combinations thereof were evaluated by comparison to results of the local lymph node assay. When evaluating 139 chemicals using combinations of three methods based on integrated testing strategy (ITS) concept (ITS-based test battery) and a sequential testing strategy (STS) weighing the predictive performance of the h-CLAT and DPRA, overall similar predictivities were found as before on the 101 chemical data set. An analysis of false negative chemicals suggested a major limitation of our strategies was the testing of low water-soluble chemicals. When excluded the negative results for chemicals with log Kow > 3.5, the sensitivity and accuracy of ITS improved to 97% (91 of 94 chemicals) and 89% (114 of 128). Likewise, the sensitivity and accuracy of STS to 98% (92 of 94) and 85% (111 of 129). Moreover, the ITS and STS also showed good correlation with local lymph node assay on three potency classifications, yielding accuracies of 74% (ITS) and 73% (STS). Thus, the inclusion of log Kow in analysis could give both strategies a higher predictive performance. PMID:25820183

  11. Test battery with the human cell line activation test, direct peptide reactivity assay and DEREK based on a 139 chemical data set for predicting skin sensitizing potential and potency of chemicals.

    PubMed

    Takenouchi, Osamu; Fukui, Shiho; Okamoto, Kenji; Kurotani, Satoru; Imai, Noriyasu; Fujishiro, Miyuki; Kyotani, Daiki; Kato, Yoshinao; Kasahara, Toshihiko; Fujita, Masaharu; Toyoda, Akemi; Sekiya, Daisuke; Watanabe, Shinichi; Seto, Hirokazu; Hirota, Morihiko; Ashikaga, Takao; Miyazawa, Masaaki

    2015-11-01

    To develop a testing strategy incorporating the human cell line activation test (h-CLAT), direct peptide reactivity assay (DPRA) and DEREK, we created an expanded data set of 139 chemicals (102 sensitizers and 37 non-sensitizers) by combining the existing data set of 101 chemicals through the collaborative projects of Japan Cosmetic Industry Association. Of the additional 38 chemicals, 15 chemicals with relatively low water solubility (log Kow > 3.5) were selected to clarify the limitation of testing strategies regarding the lipophilic chemicals. Predictivities of the h-CLAT, DPRA and DEREK, and the combinations thereof were evaluated by comparison to results of the local lymph node assay. When evaluating 139 chemicals using combinations of three methods based on integrated testing strategy (ITS) concept (ITS-based test battery) and a sequential testing strategy (STS) weighing the predictive performance of the h-CLAT and DPRA, overall similar predictivities were found as before on the 101 chemical data set. An analysis of false negative chemicals suggested a major limitation of our strategies was the testing of low water-soluble chemicals. When excluded the negative results for chemicals with log Kow > 3.5, the sensitivity and accuracy of ITS improved to 97% (91 of 94 chemicals) and 89% (114 of 128). Likewise, the sensitivity and accuracy of STS to 98% (92 of 94) and 85% (111 of 129). Moreover, the ITS and STS also showed good correlation with local lymph node assay on three potency classifications, yielding accuracies of 74% (ITS) and 73% (STS). Thus, the inclusion of log Kow in analysis could give both strategies a higher predictive performance.

  12. Late Holocene lake-level fluctuations in Walker Lake, Nevada, USA

    USGS Publications Warehouse

    Yuan, F.; Linsley, B.K.; Howe, S.S.; Lund, S.P.; McGeehin, J.P.

    2006-01-01

    Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (??), total inorganic carbon (TIC), and oxygen isotopic composition (??18O) of carbonate sediments including ostracode shells (Limnocythere ceriotuberosa) from Walker Lake allow us to extend the sediment record of lake-level fluctuations back to 2700??years B.P. There are approximately five major stages over the course of the late Holocene hydrologic evolution in Walker Lake: an early lowstand (> 2400??years B.P.), a lake-filling period (??? 2400 to ??? 1000??years B.P.), a lake-level lowering period during the Medieval Warm Period (MWP) (??? 1000 to ??? 600??years B.P.), a relatively wet period (??? 600 to ??? 100??years B.P.), and the anthropogenically induced lake-level lowering period (< 100??years B.P.). The most pronounced lowstand of Walker Lake occurred at ??? 2400??years B.P., as indicated by the relatively high values of ??18O. This is generally in agreement with the previous lower resolution paleoclimate results from Walker Lake, but contrasts with the sediment records from adjacent Pyramid Lake and Siesta Lake. The pronounced lowstand suggests that the Walker River that fills Walker Lake may have partially diverted into the Carson Sink through the Adrian paleochannel between 2700 to 1400??years B.P. ?? 2006 Elsevier B.V. All rights reserved.

  13. Nonconvergence of the Wang-Landau algorithms with multiple random walkers

    NASA Astrophysics Data System (ADS)

    Belardinelli, R. E.; Pereyra, V. D.

    2016-05-01

    This paper discusses some convergence properties in the entropic sampling Monte Carlo methods with multiple random walkers, particularly in the Wang-Landau (WL) and 1 /t algorithms. The classical algorithms are modified by the use of m -independent random walkers in the energy landscape to calculate the density of states (DOS). The Ising model is used to show the convergence properties in the calculation of the DOS, as well as the critical temperature, while the calculation of the number π by multiple dimensional integration is used in the continuum approximation. In each case, the error is obtained separately for each walker at a fixed time, t ; then, the average over m walkers is performed. It is observed that the error goes as 1 /√{m } . However, if the number of walkers increases above a certain critical value m >mx , the error reaches a constant value (i.e., it saturates). This occurs for both algorithms; however, it is shown that for a given system, the 1 /t algorithm is more efficient and accurate than the similar version of the WL algorithm. It follows that it makes no sense to increase the number of walkers above a critical value mx, since it does not reduce the error in the calculation. Therefore, the number of walkers does not guarantee convergence.

  14. Assistive devices alter gait patterns in Parkinson disease: advantages of the four-wheeled walker.

    PubMed

    Kegelmeyer, Deb A; Parthasarathy, Sowmya; Kostyk, Sandra K; White, Susan E; Kloos, Anne D

    2013-05-01

    Gait abnormalities are a hallmark of Parkinson's disease (PD) and contribute to fall risk. Therapy and exercise are often encouraged to increase mobility and decrease falls. As disease symptoms progress, assistive devices are often prescribed. There are no guidelines for choosing appropriate ambulatory devices. This unique study systematically examined the impact of a broad range of assistive devices on gait measures during walking in both a straight path and around obstacles in individuals with PD. Quantitative gait measures, including velocity, stride length, percent swing and double support time, and coefficients of variation were assessed in 27 individuals with PD with or without one of six different devices including canes, standard and wheeled walkers (two, four or U-Step). Data were collected using the GAITRite and on a figure-of-eight course. All devices, with the exception of four-wheeled and U-Step walkers significantly decreased gait velocity. The four-wheeled walker resulted in less variability in gait measures and had less impact on spontaneous unassisted gait patterns. The U-Step walker exhibited the highest variability across all parameters followed by the two-wheeled and standard walkers. Higher variability has been correlated with increased falls. Though subjects performed better on a figure-of-eight course using either the four-wheeled or the U-Step walker, the four-wheeled walker resulted in the most consistent improvement in overall gait variables. Laser light use on a U-Step walker did not improve gait measures or safety in figure-of-eight compared to other devices. Of the devices tested, the four-wheeled-walker offered the most consistent advantages for improving mobility and safety.

  15. Analysis of walker-aided walking by the healthy elderly with a walker pocket of different weights attached at different locations

    PubMed Central

    Shin, Eunji; Jeon, Byongjin; Song, Bokyung; Baek, Minho; Roh, Hyolyun

    2015-01-01

    [Purpose] This study aims to provide information on safe walker-aided walking by analyzing elderly subjects’ walking with a walker pocket of different weights attached at different locations. [Subjects and Methods] Twenty elderly right-handed males participated in the study, and a walking analyzer was used to examine their walking with a pocket attached to the left, center, and right side of the walker. The weight of the pocket was set at three levels relative to the average weight of the subject group: 0% (without pocket), 2.5% (2 kg), and 5.5% (4 kg). [Results] In terms of the pocket location, step width was the narrowest when the pocket was attached to the right side, while the other elements of walking did not change. In terms of the pocket weight, all elements of walking showed changes. A heavier pocket led to a shorter step length and stride, a greater step width, and longer time. [Conclusion] When elderly people use a pocket-attached walker, the pocket is recommended to be attached to the right side of the walker, and its weight should be kept under 5.5% of the user’s weight to ensure safe walking. PMID:26696700

  16. Geomorphic Analysis Supporting Restoration of the Walker River, Nevada

    NASA Astrophysics Data System (ADS)

    Lauer, J. W.; Echterling, C.; Majerova, M.; Wilcock, P.

    2012-12-01

    Agricultural water diversions have degraded the Walker River, Nevada, and have led to a reduction of water level at its terminus, Walker Lake. The geomorphic response of the river to water reallocation is an important issue associated with restoration of the system. To address this issue, we performed a geomorphic assessment of the portions of the river passing through the two main agricultural valleys in the watershed, Smith and Mason Valleys, Nevada. The project involved field data collection, analysis of remotely sensed data, and numerical modeling. Fieldwork focused primarily on characterizing bed and bank sediment grain size distributions and on delineating geomorphically similar reaches. The remote sensing analysis used LiDAR and air photograph mosaics from 1938, 1950, 1996, 1999, and 2006 to quantify historic changes in the active channel geometry and to identify banks that represent potential sediment sources or sinks. Polygons representing in-channel features (here defined as the scoured region between vegetation lines) were delineated by hand on each photograph. Channel centerlines were then derived from this data set and were used to identify locations of active channel movement by measuring either direct centerline offsets or local sinuosity increase rates. Both active bar area and channel migration were focused on reaches near the head of each agricultural valley, where slope decreases as the channel emerges from an upstream bedrock-controlled canyon. These same reaches also experienced large increases in width during the 1997 flood of record. The gage record shows that attenuation of this flood was most pronounced in the lower of the two agricultural valleys, Mason Valley. Surprisingly little attenuation occurred in the upstream Smith Valley, despite the relatively low relief of the valley floor, which consists primarily of Pleistocene lake deposits. The major difference between the two valleys is that the meander belt through Smith Valley is incised

  17. A review of Luxiaria Walker and its allied genus Calletaera Warren (Lepidoptera, Geometridae, Ennominae) from China.

    PubMed

    Jiang, Nan; Xue, Dayong; Han, Hongxiang

    2014-08-21

    The genus Luxiaria Walker and its allied genus Calletaera Warren in China, including 16 species in all, are reviewed. Five new species are described: C. obvia sp. nov., C. acuticornuta sp. nov., C. rotundicornuta sp. nov., C. dentata sp. nov., C. trigonoprocessus sp. nov. The species L. acutaria (Snellen, 1877) and L. tephrosaria (Moore, 1868) are newly recorded for China. Two new combinations are established: C. obliquata (Moore, 1888) comb. nov. and C. consimilaria (Leech, 1897) comb. nov. Four new synonyms are established: Eutoea Walker, 1860 (= Bithiodes Warren, 1894 syn. nov.); Calletaera Warren, 1895 (=Bithiodes Warren, 1899 syn. nov.), based on the fixation of nominal type Acidalia inexactata Walker, 1861, for the genus name Bithiodes Warren, 1894; L. emphatica Prout, 1925 (= L. costinota Inoue, 1978 syn. nov.); C. subexpressa (Walker, 1861) (= C. digrammata Wehrli, 1925 syn. nov.). Diagnoses for all Chinese species are provided. Illustrations of external features and genitalia are presented. 

  18. Spacetime Emergence of the Robertson-Walker Universe from a Matrix Model

    SciTech Connect

    Erdmenger, Johanna; Meyer, Rene; Park, Jeong-Hyuck

    2007-06-29

    Using a novel, string theory-inspired formalism based on a Hamiltonian constraint, we obtain a conformal mechanical system for the spatially flat four-dimensional Robertson-Walker Universe. Depending on parameter choices, this system describes either a relativistic particle in the Robertson-Walker background or metric fluctuations of the Robertson-Walker geometry. Moreover, we derive a tree-level M theory matrix model in this time-dependent background. Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy near the big bang, while the classical Robertson-Walker geometry emerges as the Universe expands. From our approach, we also derive the temperature of the Universe interpolating between the radiation and matter dominated eras.

  19. Spacetime emergence of the robertson-walker universe from a matrix model.

    PubMed

    Erdmenger, Johanna; Meyer, René; Park, Jeong-Hyuck

    2007-06-29

    Using a novel, string theory-inspired formalism based on a Hamiltonian constraint, we obtain a conformal mechanical system for the spatially flat four-dimensional Robertson-Walker Universe. Depending on parameter choices, this system describes either a relativistic particle in the Robertson-Walker background or metric fluctuations of the Robertson-Walker geometry. Moreover, we derive a tree-level M theory matrix model in this time-dependent background. Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy near the big bang, while the classical Robertson-Walker geometry emerges as the Universe expands. From our approach, we also derive the temperature of the Universe interpolating between the radiation and matter dominated eras.

  20. Dandy-Walker malformation in an infant with tetrasomy 9p.

    PubMed

    Cazorla Calleja, María R; Verdú, Alfonso; Félix, Valentin

    2003-04-01

    An infant with Dandy-Walker malformation and prenatally diagnosed tetrasomy 9p is reported. Chromosomal analysis of primary amniocyte culture revealed true mosaicism for two cell lines: 50% of the cells had an isochromosome 9p (pter-q13::q13-pter), and the other 50% showed a normal female karyotype (46,XX). After birth the same chromosomal abnormality was found in 75% of peripheral blood lymphocytes. Phenotypic features included intrauterine growth retardation, hypotrophy of the left side of the body with left microphthalmus, and progressive hydrocephalus secondary to Dandy-Walker malformation. Although most cases of Dandy-Walker malformation are not associated with chromosomal abnormalities, our case, together with two previously reported cases of the same association, indicates that this chromosomal disorder should be looked for in children with Dandy-Walker malformation and abnormal somatic development. PMID:12689705

  1. Alice Walker: "The Diary of an African Nun" and Dubois Double Consciousness

    ERIC Educational Resources Information Center

    Fontenot, Chester J.

    1977-01-01

    Analyzes Alice Walker's novel and notes that the plight of the African nun is that of the black intellectual or middle-class who find themselves caught between two worlds which are at once complementary and contradictory. (Author)

  2. ISS Update: Astronaut Shannon Walker – 07.17.2012

    NASA Video Gallery

    In the International Space Station flight control room at NASA’s Johnson Space Center, Houston, ISS Update commentator Amiko Kauderer interviewed Shannon Walker, NASA astronaut and Expedition 24 ...

  3. Spacetime emergence of the robertson-walker universe from a matrix model.

    PubMed

    Erdmenger, Johanna; Meyer, René; Park, Jeong-Hyuck

    2007-06-29

    Using a novel, string theory-inspired formalism based on a Hamiltonian constraint, we obtain a conformal mechanical system for the spatially flat four-dimensional Robertson-Walker Universe. Depending on parameter choices, this system describes either a relativistic particle in the Robertson-Walker background or metric fluctuations of the Robertson-Walker geometry. Moreover, we derive a tree-level M theory matrix model in this time-dependent background. Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy near the big bang, while the classical Robertson-Walker geometry emerges as the Universe expands. From our approach, we also derive the temperature of the Universe interpolating between the radiation and matter dominated eras. PMID:17678078

  4. Walker Lake, Nevada: sedimentation in an active, strike-slip related basin

    SciTech Connect

    Link, M.H.; Roberts, M.T.

    1984-04-01

    Walker Lake, Nevada, is in an active fault-controlled basin related to the right-lateral, northwest-trending Walker Lane Shear Zone on the western side of the Basin and Range province. The lake occurs in a half graben bounded on its west side by a high-angle normal fault zone along the Wassuk Range front. This fault zone may merge to the north into the Walker Lane fault system, which forms the northeast boundary of the basin. To the south of Walker Lake, the Wassuk front fault merges with an east-northeast trending left-lateral fault. The Walker Lake basin is interpreted to be a pull-apart basin formed within the triangular zone bounded by the Wassuk front, the Walker Lane, and left-lateral faults. The Walker River drainage basin occupies about 10,000 km/sup 2/ (3800 mi/sup 2/) in western Nevada and parts of California and is essentially a closed hydrologic system that drains from the crest of the Sierra Nevada in California and terminates in Walker Lake. Walker Lake trends north-northwest and is 27.4 km (17 mi) long and 8 km (5 mi) wide with water depths exceeding 30 m (100 ft). Lake Lahontan (Wisconsinian) shorelines ring Walker Lake and suggest water depths of 150 m (500 ft) above the present lake level. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and gentle, areally more extensive fans flanking the eastern shoreline (Gillis Range). The Walker River delta enters the lake from the north and is a major sediment point source for the basin. Older dissected shoreline, alluvial fan, Gilbert delta, and beach ridge deposits were built largely of coarse-grained, locally derived materials. Stromatolites, oncolites, and tufas formed along the shorelines, whereas mud and organic sediments accumulated in the lake on the west side of the basin. Extensive submerged sand flats and local sand dunes occur on the east side of the basin.

  5. Chemotaxing and haptotaxing random walkers having directional persistence

    NASA Astrophysics Data System (ADS)

    Kwon, Tae Goo; Kyoungjin Lee Team; Taeseok Daniel Yang Team

    2015-03-01

    Biological cell crawling is a rather complex process involving various bio-chemical and bio-mechanical processes, many of which are still not well understood. The difficulties in understanding the crawling are originating not just from cell-intrinsic factors but from their complex social interactions, cell-to-substrate interactions and nonlinear responses toward extrinsic factors. Here, in this report we investigate chemotactic behavior of mathematical model cells that naturally have directional persistence. A cell density is measured as a function of time and space, then the resulting steady state is compared with that of the well-known Keller-Segal model, which describes a population of chemotactic random walker. Then, we add a cell-to-cell interaction, mimicking a ``haptotaxis'' mediated interaction, to the model and access its role as for altering the steady-state cell density profile. This mathematical model system, which we have developed and considered in this work, can be quite relevant to the chemotactic responses of interacting immune cells, like microglia, moving toward and around a site of wound, as for an example. We conclude by discussing some relevant recent experimental findings.

  6. Straight strings and Friedmann-Robertson-Walker spacetimes

    SciTech Connect

    Unruh, W.G. )

    1992-10-15

    The embeddability of a straight cosmic string in a Friedmann-Robertson-Walker (FRW) universe is examined. Although previous suggestions that an exact embedding for a string with longitudinal tension equal to energy density is impossible are substantiated, it is shown that the deviations of either the external metric from the exact FRW metric or of the internal structure of the string from the exact tension equals energy density are expected to be very small, of the order of the square of the ratio of the string diameter (or the evacuated shell around the string) to the Hubble radius. Thus the lack of an exact mathematical embedding leads to negligible physical consequences. The problem with solving for an exact embedding of a string in the manner of the Swiss-cheese model is examined in detail, and it is shown that the metric in the evacuated region around the string is unique. That metric is determined to lowest order in the ratio of the evacuated region over the Hubble radius. The implications of this uniqueness for the Swiss-cheese embedding of a string are discussed.

  7. Multiple walker recognition using wireless distributed pyro-electric sensors

    NASA Astrophysics Data System (ADS)

    Li, Nanxiang; Hao, Qi

    2008-04-01

    This paper presents a wireless distributed pyroelectric sensor system, whose sensing visibilities are modulated by Frensnel lens arrays and coded masks, for multiple human walker recognition. One goal of our research is to make wireless distributed pyroelectric sensor nodes an alternative to the centralized infrared video sensors, with lower cost, lower detectability, lower power consumption and computation, and less privacy infringement. In our previous study, we succeeded in identifying individuals walking along the same path, or just randomly inside a room, with an identification rate higher than 80% for around 10 subjects, only using one wireless sensor node. To improve the identification rate and the number of subjects that can be recognized, one-by-one or simultaneously, we employ multiple sensor nodes to leverage the performance of the distributed sensor system. The fusion of pyroelectric biometrics from multiple nodes is performed at four different levels: sample, feature, score, and decision. The experimental results show that the proposed pyroelectric sensor system has potential to be a reliable biometric system for the verification/identification of a small group of human objects. Its applications include security monitoring, human-machine interfaces, and virtual environments.

  8. A jump persistent turning walker to model zebrafish locomotion

    PubMed Central

    Mwaffo, Violet; Anderson, Ross P.; Butail, Sachit; Porfiri, Maurizio

    2015-01-01

    Zebrafish are gaining momentum as a laboratory animal species for the investigation of several functional and dysfunctional biological processes. Mathematical models of zebrafish behaviour are expected to considerably aid in the design of hypothesis-driven studies by enabling preliminary in silico tests that can be used to infer possible experimental outcomes without the use of zebrafish. This study is motivated by observations of sudden, drastic changes in zebrafish locomotion in the form of large deviations in turn rate. We demonstrate that such deviations can be captured through a stochastic mean reverting jump diffusion model, a process that is commonly used in financial engineering to describe large changes in the price of an asset. The jump process-based model is validated on trajectory data of adult subjects swimming in a shallow circular tank obtained from an overhead camera. Through statistical comparison of the empirical distribution of the turn rate against theoretical predictions, we demonstrate the feasibility of describing zebrafish as a jump persistent turning walker. The critical role of the jump term is assessed through comparison with a simplified mean reversion diffusion model, which does not allow for describing the heavy-tailed distributions observed in the fish turn rate. PMID:25392396

  9. [Accidents with caterpillar Lonomia obliqua (Walker, 1855). An emerging problem].

    PubMed

    Sánchez, Matías N; Mignone Chagas, Mariana A; Casertano, Sergio A; Cavagnaro, Luis E; Peichoto, María E

    2015-01-01

    Lonomia obliqua (Walker, 1855) is a moth from the family Saturniidae, widely distributed in tropical rainforests of South America. In its larval stage (caterpillar) it is characterized by bristles that cover the animal's body. These structures are hard and branched spiny evaginations of the cuticle, underneath which a complex mixture of toxic molecules is stored. When spicules are brought into contact with the skin of people, toxins enter passively through the injury, causing not only local but also systemic poisoning (primarily hemorrhagic manifestations). When the whole animal is accidentally crushed, the insect's chitinous bristles are broken and the venomous secretions penetrate the human skin, reaching the blood circulation. Due to the numerous registered cases of erucism in Southern Brazil, the Butantan Institute has produced an antivenom able to neutralize the deleterious effects produced by contact with L. obliqua caterpillar bristles. In Argentina, these kinds of accidents are rare and restricted to the province of Misiones. Taking into account that to date there is no report in this country about clinical cases submitted to a specific treatment (antivenom), our aim is to communicate here six cases of Lonomia caterpillar-induced bleeding syndrome that were treated in the Hospital SAMIC of Puerto Iguazú (Misiones, Argentina) during 2014 with the antilonomic serum produced in Brazil. It is worthy to note that all patients evolved favorably within the first few hours, and for this reason, the use of this antivenom is recommended to treat the cases of Lonomia erucism in Argentina. PMID:26502471

  10. Field performance of the Walker Branch throughfall displacement experiment

    SciTech Connect

    Hanson, P.J.; Todd, D.E.; Edwards, N.T.; Huston, M.A.

    1994-10-06

    The authors are conducting a large-scale manipulative field experiments in an upland oak forest on the Walker Branch Watershed in eastern Tennessee USA to identify important ecosystem responses that might result from future precipitation changes. The manipulation of soil moisture is being implemented by a gravity-driven transfer of throughfall precipitation from one treatment plot to another. Throughfall is intercepted in {approx} 2,000 subcanopy troughs (0.3 x 5 m) suspended above the forest floor of the dry plots ({approx} 33% of the ground area is covered) and transferred by gravity flow across an ambient plot for subsequent distribution onto the wet treatment plot. Percent soil water is being monitored with time domain reflectometers at 310 sampling locations across the site. The experimental system is able to produce statistically significant differences in soil water content in years having both extremely dry and extremely wet conditions. Furthermore, comparisons of pre- and post-installation soil temperature measurements have documented the ability of the experimental design to produce these changes without changing the microclimate of the forest understory.

  11. Third annual Walker Branch Watershed research symposium. Program and abstracts

    SciTech Connect

    Not Available

    1992-03-01

    The methods and concepts of watershed research, originally applied in an experimental or monitoring mode to relatively small catchments, are increasingly being used at larger scales and for specific applied problems. Research at Oak Ridge National Laboratory, the Tennessee Valley Authority, the US Forest Service, and other agencies and institutions participating in this symposium reflects research over a broad range of spatial scales that is being integrated through large-scale experiments along with computer modeling and graphical interfaces. These research projects address the basic atmospheric, geophysical, biogeochemical, and biological processes that regulate the responses of forested ecosystems to natural environmental variation and anthropogenic stresses. Regional and global issues addressed by presentations include emissions of carbon dioxide, methane, and other hydrocarbons; deposition of sulfate, nitrate, and mercury; land-use changes; biological diversity; droughts; and water quality. The reports presented in this symposium illustrate a wide range of methods and approaches and focus more on concepts and techniques than on a specific physical site. Sites and projects that have contributed research results to this symposium include Walker Branch Watershed (DOE), the Coweeta Hydrologic Laboratory and LTER site (USFS and NSF), Great Smoky Mountains National Park (research funded by NPS, TVA, and EPRI), Imnavait Creek, Alaska (DOE), the TVA-Norris Whole-tree Facility (TVA and EPRI), and DOE`s Biomass Program.

  12. Design Principles of DNA Enzyme-Based Walkers: Translocation Kinetics and Photoregulation.

    PubMed

    Cha, Tae-Gon; Pan, Jing; Chen, Haorong; Robinson, Heather N; Li, Xiang; Mao, Chengde; Choi, Jong Hyun

    2015-07-29

    Dynamic DNA enzyme-based walkers complete their stepwise movements along the prescribed track through a series of reactions, including hybridization, enzymatic cleavage, and strand displacement; however, their overall translocation kinetics is not well understood. Here, we perform mechanistic studies to elucidate several key parameters that govern the kinetics and processivity of DNA enzyme-based walkers. These parameters include DNA enzyme core type and structure, upper and lower recognition arm lengths, and divalent metal cation species and concentration. A theoretical model is developed within the framework of single-molecule kinetics to describe overall translocation kinetics as well as each reaction step. A better understanding of kinetics and design parameters enables us to demonstrate a walker movement near 5 μm at an average speed of ∼1 nm s(-1). We also show that the translocation kinetics of DNA walkers can be effectively controlled by external light stimuli using photoisomerizable azobenzene moieties. A 2-fold increase in the cleavage reaction is observed when the hairpin stems of enzyme catalytic cores are open under UV irradiation. This study provides general design guidelines to construct highly processive, autonomous DNA walker systems and to regulate their translocation kinetics, which would facilitate the development of functional DNA walkers.

  13. Continuous observation of the stochastic motion of an individual small-molecule walker

    PubMed Central

    Pulcu, Gökçe Su; Mikhailova, Ellina; Choi, Lai-Sheung; Bayley, Hagan

    2016-01-01

    Motion - be it the ability to change shape, rotate or translate - is an important potential asset for functional nanostructures. For translational motion, a variety of DNA-based and small-molecule walkers have been created, but observing the translational motion of individual molecules in real time remains a significant challenge. Here, we show that the movement of a small-molecule walker along a 5-foothold track can be monitored continuously within a protein nanoreactor. The walker is an organoarsenic(III) molecule with exchangeable thiol ligands, and the track a line of cysteine residues 6Å apart within an α-haemolysin protein pore that acts as the nanoreactor. Changes in the flow of ionic current through the pore reflect the individual steps of a single walker, which require the making and breaking of As-S bonds, and occur in aqueous solution at neutral pH and room temperature. The walker moves considerably faster (~0.7 s per step) than previous walkers based on covalent chemistry and is weakly processive (6 ± 1 steps per outing). It shows weak net directional movement, which can be described by a thermodynamic sink arising from the different environments of the cysteines that constitute the track. PMID:25486119

  14. Hydrologic Setting and Conceptual Hydrologic Model of the Walker River Basin, West-Central Nevada

    USGS Publications Warehouse

    Lopes, Thomas J.; Allander, Kip K.

    2009-01-01

    The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. Between 1882 and 2008, agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-ft. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes the hydrologic setting of the Walker River basin and a conceptual hydrologic model of the relations among streams, groundwater, and Walker Lake with emphasis on the lower Walker River basin from Wabuska to Hawthorne, Nevada. The Walker River basin is about 3,950 square miles and straddles the California-Nevada border. Most streamflow originates as snowmelt in the Sierra Nevada. Spring runoff from the Sierra Nevada typically reaches its peak during late May to early June with as much as 2,800 cubic feet per second in the Walker River near Wabuska. Typically, 3 to 4 consecutive years of below average streamflow are followed by 1 or 2 years of average or above average streamflow. Mountain ranges are comprised of consolidated rocks with low hydraulic conductivities, but consolidated rocks transmit water where fractured. Unconsolidated sediments include fluvial deposits along the active channel of the Walker River, valley floors, alluvial slopes, and a playa. Sand and gravel deposited by the Walker River likely are discontinuous strata throughout the valley floor. Thick clay strata likely were deposited in Pleistocene Lake Lahontan and are horizontally continuous, except where strata have been eroded by the Walker River. At Walker Lake, sediments mostly are clay interbedded with alluvial slope, fluvial, and deltaic deposits along the lake margins. Coarse sediments form a multilayered, confined-aquifer system that could extend several miles from the shoreline

  15. Electro-actuated hydrogel walkers with dual responsive legs.

    PubMed

    Morales, Daniel; Palleau, Etienne; Dickey, Michael D; Velev, Orlin D

    2014-03-01

    Stimuli responsive polyelectrolyte hydrogels may be useful for soft robotics because of their ability to transform chemical energy into mechanical motion without the use of external mechanical input. Composed of soft and biocompatible materials, gel robots can easily bend and fold, interface and manipulate biological components and transport cargo in aqueous solutions. Electrical fields in aqueous solutions offer repeatable and controllable stimuli, which induce actuation by the re-distribution of ions in the system. Electrical fields applied to polyelectrolyte-doped gels submerged in ionic solution distribute the mobile ions asymmetrically to create osmotic pressure differences that swell and deform the gels. The sign of the fixed charges on the polyelectrolyte network determines the direction of bending, which we harness to control the motion of the gel legs in opposing directions as a response to electrical fields. We present and analyze a walking gel actuator comprised of cationic and anionic gel legs made of copolymer networks of acrylamide (AAm)/sodium acrylate (NaAc) and acrylamide/quaternized dimethylaminoethyl methacrylate (DMAEMA Q), respectively. The anionic and cationic legs were attached by electric field-promoted polyion complexation. We characterize the electro-actuated response of the sodium acrylate hydrogel as a function of charge density and external salt concentration. We demonstrate that "osmotically passive" fixed charges play an important role in controlling the bending magnitude of the gel networks. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices and robots in aqueous solutions.

  16. Obituary: Richard L. (Dick) Walker, Jr., 1938-2005

    NASA Astrophysics Data System (ADS)

    Pier, Jeffrey R.; Mason, Brian

    2005-12-01

    Dick Walker, 67, died 30 March 2005 in Flagstaff, AZ, following a long illness. He was born on 9 March 1938 in Hampton, Iowa and grew up in Waterloo, Iowa. As a child, Dick was fascinated with astronomy and built his own telescope. He saved his pennies and bought and read every book on the subject he could find. He also raised pigeons, naming four of them Hertzsprung, Hoyle, Gamow, and Kron. In 1957, the year Sputnik was launched, Dick began his college studies at the University of Northern Iowa in Cedar Falls. In 1959, he transferred to the State University of Iowa (subsequently renamed the University of Iowa) in Iowa City, where he earned a BA degree in astronomy and physics in 1963. He joined the staff of the U.S. Naval Observatory in Washington, DC, where he worked in the Time Service Division for a year before his assignment to the Astrometry and Astrophysics Division. Dick relocated to Flagstaff, AZ, in 1966 to continue his Naval Observatory service at the Flagstaff Station. His retirement in May 1999, ended a thirty-six-year career with USNO. Dick was first and foremost an observational astronomer. From the mid 1960s through the late 1970s, much of Dick's time was devoted to the measurement of binary stars, observing with the 12-inch and 26-inch refractors in Washington and later the 40-inch and 61-inch reflectors in Flagstaff. He also made many trips to Lick Observatory to work with the 36-inch Clark Refractor there. During this time he consulted with Charles Worley, who was observing on the 26-inch, to make sure time was well-spent examining doubles that could not be observed in Washington. This period of observing overlapped with the early years of speckle interferometry, and Dick's observations, made with the largest telescope used for micrometry at the time, were very important for ascertaining the veracity of this new technique. He was a studious and very careful observer of doubles and made over 8,000 measures, resulting in almost 3,000 mean positions

  17. A retrospective benefit-cost analysis of the 1997 stair-fall requirements for baby walkers.

    PubMed

    Rodgers, Gregory B; Leland, Elizabeth W

    2008-01-01

    Based on estimates from the U.S. Consumer Product Safety Commission (CPSC), there were about 25,000 baby walker-related injuries treated annually in U.S. hospital emergency departments during the early 1990s. This amounted to about 8 injuries for every 1000 baby walkers in use. Most injuries resulted from falls down stairs. After CPSC initiated a regulatory proceeding in 1994, the CPSC staff worked with industry to address the stair-fall hazard. This cooperative effort resulted in requirements designed to prevent stair-fall injuries that became effective in 1997 as part of a revised voluntary safety standard. This study presents a retrospective benefit-cost analysis of the 1997 stair-fall requirements. The benefits were defined as the reduction in the costs of injuries resulting from the use of the safer walkers. The costs were defined as the additional resource costs associated with making baby walkers safer. The study found that the stair-fall requirements were highly effective in reducing the risk of stair-fall injury, and that the benefits of the requirements substantially exceeded the costs. The expected net benefits (i.e., benefits minus costs) amounted to an average of about $169 per walker, over the walker's expected product life. Given current U.S. sales of about 600,000 baby walkers annually, the present value of the expected net benefits associated with 1 year's production amounts to over $100 million annually. A sensitivity analysis showed that the major findings were robust with respect to variations in underlying assumptions.

  18. Reach-Averaged Sediment Transport Model for the Walker River, Nevada

    NASA Astrophysics Data System (ADS)

    Majerova, M.; Wilcock, P.; Lauer, J. W.

    2012-12-01

    Restoration plans for Walker River and Walker Lake, Nevada, include changes in the flow hydrograph and delivery of water to the terminal lake. The change in flow is closely related to the possible changes in sediment transport rates and deposition along the river channel in two major alluvial valleys of Walker River. In support of restoration efforts in Walker River Basin, we have developed a sediment transport model for approximately 100 km of Walker River, including West and East Forks, and main stem. We have identified reaches with similar geomorphic processes using high resolution LiDAR data and aerial photographs. The channel geometry was extracted from the LiDAR data and combined with field observations. The geometry was later averaged over the individual reaches in order to capture trends in channel width, depth and elevation. Lateral source of sediment and lateral migration rate were derived from historical photographs. We have developed 1d hydraulic and transport model which was tested against flow and transport observations at multiple locations along the system. The use of 1d model allowed us to concentrate on the scale and resolution at which reliable predictions of sediment transport can be made. The results help identified specific reaches, as well as predict geomorphic trends that could occur with the restored flow regime.

  19. The fire-walker's high: affect and physiological responses in an extreme collective ritual.

    PubMed

    Fischer, Ronald; Xygalatas, Dimitris; Mitkidis, Panagiotis; Reddish, Paul; Tok, Penny; Konvalinka, Ivana; Bulbulia, Joseph

    2014-01-01

    How do people feel during extreme collective rituals? Despite longstanding speculation, few studies have attempted to quantify ritual experiences. Using a novel pre/post design, we quantified physiological fluctuations (heart rates) and self-reported affective states from a collective fire-walking ritual in a Mauritian Hindu community. Specifically, we compared changes in levels of happiness, fatigue, and heart rate reactivity among high-ordeal participants (fire-walkers), low-ordeal participants (non-fire-walking participants with familial bonds to fire-walkers) and spectators (unrelated/unknown to the fire-walkers). We observed that fire-walkers experienced the highest increase in heart rate and reported greater happiness post-ritual compared to low-ordeal participants and spectators. Low-ordeal participants reported increased fatigue after the ritual compared to both fire-walkers and spectators, suggesting empathetic identification effects. Thus, witnessing the ritualistic suffering of loved ones may be more exhausting than experiencing suffering oneself. The findings demonstrate that the level of ritual involvement is important for shaping affective responses to collective rituals. Enduring a ritual ordeal is associated with greater happiness, whereas observing a loved-one endure a ritual ordeal is associated with greater fatigue post-ritual. PMID:24586315

  20. Does the Walker Lane extend through the Nevada test site region

    SciTech Connect

    Fridrich, C.; O'Leary, D. . Denver Federal Center)

    1993-04-01

    The southeastern terminus of the Walker Lane is poorly defined and poorly understood. Recent work in and around the Nevada Test Site (NTS) suggests the presence of a structural zone that may be an extension of the Walker Lane, and that may be continuous with the Las Vegas valley shear zone farther to the southeast. Unlike the Walker Lane, large through-going strike-slip faults have not been found in the NTS zone. Instead, the strike-slip faults present are few, are relatively short, commonly consist of diffuse fault zones, are interconnected poorly if at all, and largely appear to represent zones of accommodation between domains in which extension occurred at different times and to different degrees. However, the majority of these right-slip and left-slip faults are northwest-trending and northeast-trending, respectively, suggesting that plate motions may have played a role in the creation of these accommodation zones. An obstacle to understanding the NTS zone is that major ignimbrite sheets and calderas of the southwestern Nevada volcanic field (SNVF) formed in this zone at the height of late Tertiary tectonic activity, possibly burying much of the structural evidence. The NTS zone could represent an intersection of the Walker Lane with another major structural feature, a significant bend in the Walker Lane, or a transtensional tear that localized accommodation structures as well as the prominent late Miocene calderas of the SNVF. Ongoing field work is aimed at determining which of these and competing interpretations is best.

  1. Hydrologic data for the Walker River Basin, Nevada and California, water years 2010–14

    USGS Publications Warehouse

    Pavelko, Michael T.; Orozco, Erin L.

    2015-12-10

    Walker Lake is a threatened and federally protected desert terminal lake in western Nevada. To help protect the desert terminal lake and the surrounding watershed, the Bureau of Reclamation and U.S. Geological Survey have been studying the hydrology of the Walker River Basin in Nevada and California since 2004. Hydrologic data collected for this study during water years 2010 through 2014 included groundwater levels, surface-water discharge, water chemistry, and meteorological data. Groundwater levels were measured in wells, and surface-water discharge was measured in streams, canals, and ditches. Water samples for chemical analyses were collected from wells, streams, springs, and Walker Lake. Chemical analyses included determining physical properties; the concentrations of major ions, nutrients, trace metals, dissolved gases, and radionuclides; and ratios of the stable isotopes of hydrogen and oxygen. Walker Lake water properties and meteorological parameters were monitored from a floating platform on the lake. Data collection methods followed established U.S. Geological Survey guidelines, and all data are stored in the National Water Information System database. All of the data are presented in this report and accessible on the internet, except multiple-depth Walker Lake water-chemistry data, which are available only in this report.

  2. The fire-walker's high: affect and physiological responses in an extreme collective ritual.

    PubMed

    Fischer, Ronald; Xygalatas, Dimitris; Mitkidis, Panagiotis; Reddish, Paul; Tok, Penny; Konvalinka, Ivana; Bulbulia, Joseph

    2014-01-01

    How do people feel during extreme collective rituals? Despite longstanding speculation, few studies have attempted to quantify ritual experiences. Using a novel pre/post design, we quantified physiological fluctuations (heart rates) and self-reported affective states from a collective fire-walking ritual in a Mauritian Hindu community. Specifically, we compared changes in levels of happiness, fatigue, and heart rate reactivity among high-ordeal participants (fire-walkers), low-ordeal participants (non-fire-walking participants with familial bonds to fire-walkers) and spectators (unrelated/unknown to the fire-walkers). We observed that fire-walkers experienced the highest increase in heart rate and reported greater happiness post-ritual compared to low-ordeal participants and spectators. Low-ordeal participants reported increased fatigue after the ritual compared to both fire-walkers and spectators, suggesting empathetic identification effects. Thus, witnessing the ritualistic suffering of loved ones may be more exhausting than experiencing suffering oneself. The findings demonstrate that the level of ritual involvement is important for shaping affective responses to collective rituals. Enduring a ritual ordeal is associated with greater happiness, whereas observing a loved-one endure a ritual ordeal is associated with greater fatigue post-ritual.

  3. Effects of celecoxib and ibuprofen on metabolic disorders induced by Walker-256 tumor in rats.

    PubMed

    de Souza, Camila Oliveira; Kurauti, Mirian Ayumi; de Fatima Silva, Flaviane; de Morais, Hely; Borba-Murad, Glaucia Regina; de Andrade, Fábio Goulart; de Souza, Helenir Medri

    2015-01-01

    The contribution of anti-inflammatory property of celecoxib in the improvement of metabolic disorders in cancer is unknown. The purpose of this study was to compare the effects of celecoxib and ibuprofen, non-steroidal anti-inflammatory drugs (NSAIDs), on several metabolic changes observed in Walker-256 tumor-bearing rats. The effects of these NSAIDs on the tumor growth were also assessed. Celecoxib or ibuprofen (both at 25 mg/Kg) was administered orally for 12 days, beginning on the day the rats were inoculated with Walker-256 tumor cells. Celecoxib treatment prevented the losses in body mass and mass of retroperitoneal adipose tissue, gastrocnemius, and extensor digitorum longus muscles in tumor-bearing rats. Celecoxib also prevented the rise in blood levels of triacylglycerol, urea, and lactate, the inhibition of peripheral response to insulin and hepatic glycolysis, and tended to attenuate the decrease in the food intake, but had no effect on the reduction of glycemia induced by the tumor. In addition, celecoxib treatment increased the number of Walker-256 cells with signs of apoptosis and the tumor necrosis area and prevented the tumor growth. In contrast, ibuprofen treatment had no effect on metabolic parameters affected by the Walker-256 tumor or tumor growth. It can be concluded that celecoxib, unlike ibuprofen, ameliorated several metabolic changes in rats with Walker-256 tumor due to its anti-tumor effect and not its anti-inflammatory property.

  4. Mary Edwards Walker, M.D.: a feminist physician a century ahead of her time.

    PubMed

    Spiegel, A D; Suskind, P B

    1996-06-01

    In her teens, Mary Edwards Walker already wore the "bloomer" outfit began to campaign for reforming the "unhygienic" clothing of women. Assertively, she attended medical school and earned her M.D. degree. Due to prejudice, her practice did not flourish and she moved to Washington to offer her medical services to the Union as the Civil War began. Rebuffed by the male medical bureaucrats, she volunteered her services anyway. Eventually, she was awarded the Congressional Medal of Honor, the only women to ever gain such distinction. After the war, Walker became a journalist, an author of two sensational books, a political lobbyist, a suffrage campaigner, a professional and public lecturer, an ardent dress reformer, a peace activist, a Utopianist and a women's right advocate. Light-years ahead of her times, Dr. Walker was an intelligent, independent, irrepressible and indefatigable proponent for a host of worthy causes.

  5. Very Early In-Utero Diagnosis of Walker-Warburg Phenotype: The Cutting Edge of Technology

    PubMed Central

    Achiron, R.; Katorza, E.; Reznik-Wolf, H.; Pras, E.; Kidron, D.; Berkenstadtt, M.

    2016-01-01

    Background: Walker-Warburg phenotype is a severe and lethal autosomal recessive disorder, belonging to a group of congenital malformations defined as abnormal pial basement membrane formation. So far, prenatal diagnosis was considered possible only during late pregnancy. Methods: First trimester assessment of a pregnancy suspected to be affected by Walker-Warburg phenotype, using a high-resolution transvaginal ultrasound probe (6–12 MHz), T2 MR imaging (1.5T), molecular genetics and histopathology. Results: Very early diagnosis of the Walker-Warburg phenotype at 11 weeks of gestation proved possible by depicting the classic signs of this entity, confirmed by molecular genetics, post-abortion MR imaging and histopathology. Conclusion: Advancements in ultrasound equipment and technology, molecular genetics and histopathology have made very early detection of this syndrome possible, thus shedding new light on the natural history of this malformation.

  6. Dandy-Walker syndrome forming a giant occipital meningocele--case report.

    PubMed

    Todo, T; Usui, M; Araki, F

    1993-12-01

    A boy was born with Dandy-Walker syndrome associated with a giant occipital meningocele, cleft lip, and cleft palate. The meningocele was actually a component of the giant posterior fossa cyst which communicated with the fourth ventricle. A cyst-peritoneal shunt achieved a considerable decrease in the size of the meningocele, but decubital ulcers developed due to restricted head movement caused by the occipital lesion. Cranioplasty removed a wide area of the inferior occipital bone, and the boundary between the superior occipital and parietal bones was thinned to allow free bending of the bone flap. The meningocele was removed totally in the third operation, but infection of the wound and pneumonia developed, causing death. The coexistence of Dandy-Walker syndrome and occipital meningocele, together with midline facial anomalies, may suggest a later pathogenesis of Dandy-Walker syndrome than previously believed. PMID:7512233

  7. Mary Edwards Walker, M.D.: a feminist physician a century ahead of her time.

    PubMed

    Spiegel, A D; Suskind, P B

    1996-06-01

    In her teens, Mary Edwards Walker already wore the "bloomer" outfit began to campaign for reforming the "unhygienic" clothing of women. Assertively, she attended medical school and earned her M.D. degree. Due to prejudice, her practice did not flourish and she moved to Washington to offer her medical services to the Union as the Civil War began. Rebuffed by the male medical bureaucrats, she volunteered her services anyway. Eventually, she was awarded the Congressional Medal of Honor, the only women to ever gain such distinction. After the war, Walker became a journalist, an author of two sensational books, a political lobbyist, a suffrage campaigner, a professional and public lecturer, an ardent dress reformer, a peace activist, a Utopianist and a women's right advocate. Light-years ahead of her times, Dr. Walker was an intelligent, independent, irrepressible and indefatigable proponent for a host of worthy causes. PMID:8726211

  8. Mean first-passage times of non-Markovian random walkers in confinement.

    PubMed

    Guérin, T; Levernier, N; Bénichou, O; Voituriez, R

    2016-06-16

    The first-passage time, defined as the time a random walker takes to reach a target point in a confining domain, is a key quantity in the theory of stochastic processes. Its importance comes from its crucial role in quantifying the efficiency of processes as varied as diffusion-limited reactions, target search processes or the spread of diseases. Most methods of determining the properties of first-passage time in confined domains have been limited to Markovian (memoryless) processes. However, as soon as the random walker interacts with its environment, memory effects cannot be neglected: that is, the future motion of the random walker does not depend only on its current position, but also on its past trajectory. Examples of non-Markovian dynamics include single-file diffusion in narrow channels, or the motion of a tracer particle either attached to a polymeric chain or diffusing in simple or complex fluids such as nematics, dense soft colloids or viscoelastic solutions. Here we introduce an analytical approach to calculate, in the limit of a large confining volume, the mean first-passage time of a Gaussian non-Markovian random walker to a target. The non-Markovian features of the dynamics are encompassed by determining the statistical properties of the fictitious trajectory that the random walker would follow after the first-passage event takes place, which are shown to govern the first-passage time kinetics. This analysis is applicable to a broad range of stochastic processes, which may be correlated at long times. Our theoretical predictions are confirmed by numerical simulations for several examples of non-Markovian processes, including the case of fractional Brownian motion in one and higher dimensions. These results reveal, on the basis of Gaussian processes, the importance of memory effects in first-passage statistics of non-Markovian random walkers in confinement. PMID:27306185

  9. Mean first-passage times of non-Markovian random walkers in confinement

    NASA Astrophysics Data System (ADS)

    Guérin, T.; Levernier, N.; Bénichou, O.; Voituriez, R.

    2016-06-01

    The first-passage time, defined as the time a random walker takes to reach a target point in a confining domain, is a key quantity in the theory of stochastic processes. Its importance comes from its crucial role in quantifying the efficiency of processes as varied as diffusion-limited reactions, target search processes or the spread of diseases. Most methods of determining the properties of first-passage time in confined domains have been limited to Markovian (memoryless) processes. However, as soon as the random walker interacts with its environment, memory effects cannot be neglected: that is, the future motion of the random walker does not depend only on its current position, but also on its past trajectory. Examples of non-Markovian dynamics include single-file diffusion in narrow channels, or the motion of a tracer particle either attached to a polymeric chain or diffusing in simple or complex fluids such as nematics, dense soft colloids or viscoelastic solutions. Here we introduce an analytical approach to calculate, in the limit of a large confining volume, the mean first-passage time of a Gaussian non-Markovian random walker to a target. The non-Markovian features of the dynamics are encompassed by determining the statistical properties of the fictitious trajectory that the random walker would follow after the first-passage event takes place, which are shown to govern the first-passage time kinetics. This analysis is applicable to a broad range of stochastic processes, which may be correlated at long times. Our theoretical predictions are confirmed by numerical simulations for several examples of non-Markovian processes, including the case of fractional Brownian motion in one and higher dimensions. These results reveal, on the basis of Gaussian processes, the importance of memory effects in first-passage statistics of non-Markovian random walkers in confinement.

  10. Presence of dynorphin-like immunoreactivity but not opiate binding in Walker-256 tumors

    SciTech Connect

    Bryant, H.U.; Conroy, W.G.; Isom, G.E.; Malven, P.V.; Yim, G.K.W.

    1985-07-15

    Walker-256 tumor tissue was removed from rats on day 8 of tumor growth. An acidified methanol extract of the tumor tissue was assayed for immunoreactive (ir) dynorphin-A 1-17 (DYN-17) and ir-dynorphin-A (DYN-8). Levels of ir-DYN-17 and ir-DYN-8 were nearly 4- and 8-fold higher, respectively, in tumors versus normal muscle. However, tumor homogenates did not exhibit specific /sup 3/H-naloxone binding. These results indicate that although the Walker-256 carcinosarcoma may produce opioids, it is unlikely that these ectopic substances have direct opioid actions on the tumor itself. 34 references, 1 figure.

  11. Fraction of uninfected walkers in the one-dimensional Potts model.

    PubMed

    O'Donoghue, S J; Bray, A J

    2002-05-01

    The dynamics of the one-dimensional q-state Potts model, in the zero-temperature limit, can be formulated through the motion of random walkers which either annihilate (A+A-->Phi) or coalesce (A+A-->A) with a q-dependent probability. We consider all of the walkers in this model to be mutually infectious. Whenever two walkers meet, they experience mutual contamination. Walkers which avoid an encounter with another random walker up to time t remain uninfected. The fraction of uninfected walkers is known to obey a power-law decay U(t) approximately t(-phi(q)), with a nontrivial exponent phi(q) [C. Monthus, Phys. Rev. E 54, 4844 (1996); S. N. Majumdar and S. J. Cornell, ibid. 57, 3757 (1998)]. We probe the numerical values of phi(q) to a higher degree of accuracy than previous simulations and relate the exponent phi(q) to the persistence exponent theta(q) [B. Derrida, V. Hakim, and V. Pasquier, Phys. Rev. Lett. 75, 751 (1995)], through the relation phi(q)=gamma(q)theta(q) where gamma is an exponent introduced in [S. J. O'Donoghue and A. J. Bray, preceding paper, Phys. Rev. E 65, 051113 (2002)]. Our study is extended to include the coupled diffusion-limited reaction A+A-->B, B+B-->A in one dimension with equal initial densities of A and B particles. We find that the density of walkers decays in this model as rho(t) approximately t(-1/2). The fraction of sites unvisited by either an A or a B particle is found to obey a power law, P(t) approximately t(-theta) with theta approximately 1.33. We discuss these exponents within the context of the q-state Potts model and present numerical evidence that the fraction of walkers which remain uninfected decays as U(t) approximately t(-phi), where phi approximately 1.13 when infection occurs between like particles only, and phi approximately 1.93 when we also include cross-species contamination. We find that the relation between phi and theta in this model can also be characterized by an exponent gamma, where similarly, phi

  12. Suppression of Walker breakdown in magnetic domain wall propagation through structural control of spin wave emission

    NASA Astrophysics Data System (ADS)

    Burn, David M.; Atkinson, Del

    2013-06-01

    The control of individual magnetic domain walls has potential for future spintronic memory and data processing applications. The speed and reliability of such devices are determined by the dynamic properties of the domain walls. Typically, spin precession limitations lead to Walker breakdown, limiting wall velocity resulting in low mobility. Here, we show the suppression of Walker breakdown by the careful design of small amplitude periodic nanowire structuring to match the periodicity of domain wall spin structure transformations. This opens up a channel for energy dissipation via spin wave emission, allowing a domain wall to maintain its spin structure during propagation.

  13. Test pilots 1962 - Armstrong, Walker, Dana, Peterson, McKay, Thompson, Butchart

    NASA Technical Reports Server (NTRS)

    1962-01-01

    The research pilots at what in 1962 was called the Flight Research Center standing in front of the X-1E. They are (left to right) Neil Armstrong, Joe Walker, Bill Dana, Bruce Peterson, Jack McKay, Milt Thompson, and Stan Butchart. of the group, Armstrong, Walker, Dana, McKay and Thompson all flew the X-15. Bruce Peterson flew the M2-F2 and HL-10 lifting bodies, while Stan Butchart was the B-29 drop plane pilot for many of the D-558-II and X-1 series research aircraft.

  14. Experimental Studies of Wheelchair and Walker Users Passing Through Doors with Different Opening Force.

    PubMed

    Nersveen, Jonny

    2016-01-01

    Users of walkers and users of different categories of wheelchairs tested doors with different opening force, aiming to reveal the limit that these groups of people could manage on an everyday basis. 94.7% of the wheelchair users reported that a door opening force of 30 N was acceptable, while as 92.1% of this group described 40 N as acceptable. Similarly, 100% of the walker users reported that a door opening force of 30 N was acceptable, while as 87,5% of this group described 40 N as acceptable. PMID:27534356

  15. The Care and Feeding of the Creative Spirit: Teaching Alice Walker's "In Search of Our Mothers' Gardens."

    ERIC Educational Resources Information Center

    Martin, Terry

    1997-01-01

    Asserts that Alice Walker is one contemporary writer whose voice deserves to be heard in secondary English language arts classrooms. Suggests a number of class activities (dealing with imagery, organization, literary techniques, and writing and identity) for Walker's essay "In Search of Our Mothers' Gardens." (SR)

  16. 77 FR 67811 - Porter-Walker LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Porter-Walker LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding of Porter-Walker...

  17. Multiple-Replica Strategies for Free-Energy Calculations in NAMD: Multiple-Walker Adaptive Biasing Force and Walker Selection Rules.

    PubMed

    Comer, Jeffrey; Phillips, James C; Schulten, Klaus; Chipot, Christophe

    2014-12-01

    From the most powerful supercomputers to multicore desktops and laptops, parallel computing architectures have been in the mainstream for some time. However, numerical schemes for calculating free energies in molecular systems that directly leverage this hardware paradigm, usually taking the form of multiple-replica strategies, are just now on the cusp of becoming standard practice. Here, we present a modification of the popular molecular dynamics program NAMD that is envisioned to facilitate the use of powerful multiple-replica strategies to improve ergodic sampling for a specific class of free-energy methods known as adaptive biasing force. We describe the software implementation in a so-called multiple-walker context, alongside the interface that makes the proposed approach accessible to the end users. We further evaluate the performance of the adaptive biasing force multiple-walker strategy for a model system, namely, the reversible folding of a short peptide, and show, in particular, in regions of the transition coordinate where convergence of the free-energy calculation is encumbered by hidden barriers, that the multiple-walker strategy can yield far more reliable results in appreciably less real time on parallel architectures, relative to standard, single-replica calculations. PMID:26583211

  18. Multiple-Replica Strategies for Free-Energy Calculations in NAMD: Multiple-Walker Adaptive Biasing Force and Walker Selection Rules.

    PubMed

    Comer, Jeffrey; Phillips, James C; Schulten, Klaus; Chipot, Christophe

    2014-12-01

    From the most powerful supercomputers to multicore desktops and laptops, parallel computing architectures have been in the mainstream for some time. However, numerical schemes for calculating free energies in molecular systems that directly leverage this hardware paradigm, usually taking the form of multiple-replica strategies, are just now on the cusp of becoming standard practice. Here, we present a modification of the popular molecular dynamics program NAMD that is envisioned to facilitate the use of powerful multiple-replica strategies to improve ergodic sampling for a specific class of free-energy methods known as adaptive biasing force. We describe the software implementation in a so-called multiple-walker context, alongside the interface that makes the proposed approach accessible to the end users. We further evaluate the performance of the adaptive biasing force multiple-walker strategy for a model system, namely, the reversible folding of a short peptide, and show, in particular, in regions of the transition coordinate where convergence of the free-energy calculation is encumbered by hidden barriers, that the multiple-walker strategy can yield far more reliable results in appreciably less real time on parallel architectures, relative to standard, single-replica calculations.

  19. [Needs, uses, cons-pros, good practices and opportunities about walker in elderly with loss of autonomy].

    PubMed

    Mézière, Anthony; Schonheit, Claire; Moreau, Caroline; Baudry, Elodie; Monié, Marguerite; Piette, François; Curtis, Valentine; Pasqui, Viviane

    2015-01-01

    Non-use of the walker may be secondary to an initial inappropriate prescribing, a lack of adequate training, a lack of monitoring and side effects of using. Improving both stability and mobility in users is due to several biomechanical mechanisms. The benefits of walker are: general physiological effects, more confidence, better social life and decrease in the burden of care. The disadvantages of walker are: technical or practical aspects criticized by users, musculoskeletal disorders, delayed reaction time, fall risk and stigma. Few scientific data evaluating the interest of the walker concerning mobility exist, thus recommendations are low grade and are often taken from professional clinical experiences. The choice of technical walking assistance depends on the pathology and biomechanical mechanism. The walker robots are few distributed.

  20. [Needs, uses, cons-pros, good practices and opportunities about walker in elderly with loss of autonomy].

    PubMed

    Mézière, Anthony; Schonheit, Claire; Moreau, Caroline; Baudry, Elodie; Monié, Marguerite; Piette, François; Curtis, Valentine; Pasqui, Viviane

    2015-01-01

    Non-use of the walker may be secondary to an initial inappropriate prescribing, a lack of adequate training, a lack of monitoring and side effects of using. Improving both stability and mobility in users is due to several biomechanical mechanisms. The benefits of walker are: general physiological effects, more confidence, better social life and decrease in the burden of care. The disadvantages of walker are: technical or practical aspects criticized by users, musculoskeletal disorders, delayed reaction time, fall risk and stigma. Few scientific data evaluating the interest of the walker concerning mobility exist, thus recommendations are low grade and are often taken from professional clinical experiences. The choice of technical walking assistance depends on the pathology and biomechanical mechanism. The walker robots are few distributed. PMID:25964157

  1. Walker-A threonine couples nucleotide occupancy with the chaperone activity of the AAA+ ATPase ClpB

    PubMed Central

    Nagy, Maria; Wu, Hui-Chuan; Liu, Zhonghua; Kedzierska-Mieszkowska, Sabina; Zolkiewski, Michal

    2009-01-01

    Hexameric AAA+ ATPases induce conformational changes in a variety of macromolecules. AAA+ structures contain the nucleotide-binding P-loop with the Walker A sequence motif: GxxGxGK(T/S). A subfamily of AAA+ sequences contains Asn in the Walker A motif instead of Thr or Ser. This noncanonical subfamily includes torsinA, an ER protein linked to human dystonia and DnaC, a bacterial helicase loader. Role of the noncanonical Walker A motif in the functionality of AAA+ ATPases has not been explored yet. To determine functional effects of introduction of Asn into the Walker A sequence, we replaced the Walker-A Thr with Asn in ClpB, a bacterial AAA+ chaperone which reactivates aggregated proteins. We found that the T-to-N mutation in Walker A partially inhibited the ATPase activity of ClpB, but did not affect the ClpB capability to associate into hexamers. Interestingly, the noncanonical Walker A sequence in ClpB induced preferential binding of ADP vs. ATP and uncoupled the linkage between the ATP-bound conformation and the high-affinity binding to protein aggregates. As a consequence, ClpB with the noncanonical Walker A sequence showed a low chaperone activity in vitro and in vivo. Our results demonstrate a novel role of the Walker-A Thr in sensing the nucleotide's γ-phosphate and in maintaining an allosteric linkage between the P-loop and the aggregate binding site of ClpB. We postulate that AAA+ ATPases with the noncanonical Walker A might utilize distinct mechanisms to couple the ATPase cycle with their substrate-remodeling activity. PMID:19177562

  2. [Stress parameters and behaviour of horses in walkers with and without the use of electricity].

    PubMed

    Giese, C; Gerber, V; Howald, M; Bachmann, I; Burger, D

    2014-04-01

    In order to investigate stress responses of horses in walkers with and without electricity, 12 horses were trained during 3 weeks in a horse walker with and without the use of electricity (3.7 kV). To evaluate the stress response, cortisol levels in the blood were measured, the heart rate was monitored using the Polar® system and the behaviour was evaluated. Neither the cortisol levels nor the heart rates showed any relevant statistically significant difference between horses moved in the horse walker with or without the use of electricity. The highest cortisol levels and heart rates were recorded during the first week (habituation period). A significant difference could be observed regarding spontaneous compartment changes: while this happened mainly during the first week and before the first use of electricity, no horses changed compartments in the periods when electricity was used and thereafter. The results of this study indicate that the use of electricity in the horse walker does not seem to cause significant detectable stress in the horses.

  3. Joseph Walker, a Black Playwright, Exhorts Counselors and Black People to Deal With Themselves

    ERIC Educational Resources Information Center

    Walker, Joseph

    1976-01-01

    This is an interview with Joseph Walker, black playwright. He attempts to reflect back to the black community their experience in a white controlled world. In this interview, he discusses his views of the black experience, the pressures on man-woman relationships, and the role of black psychiatry. (NG)

  4. High Performance Sustainable School Design: Roy Lee Walker Elementary, McKinney, Texas.

    ERIC Educational Resources Information Center

    SHW Group, Inc., Dallas, TX.

    This document describes the sustainable features of the Roy Lee Walker Elementary School (Texas), a prototype "Eco Education" school that blends the physical environment with the student learning process while protecting the site. The document also presents the process of integrating sustainability criteria in all phases of the school's life…

  5. The energy localization problem and the renormalized vacuum energy in static Robertson-Walker universes

    NASA Astrophysics Data System (ADS)

    Baym, Selçuk Ş.

    1994-10-01

    We calculate the renormalized quantum vacuum energy inside a spherical boundary for the massless conformal scalar field in curved background Robertson-Walker geometry. We use the mode sum method with an exponential cutoff. In our calculations we do not make assumptions about the exterior geometry or the global topology of the universe.

  6. 75 FR 35282 - Third Party Testing for Certain Children's Products; Infant Walkers: Requirements for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... section 14(a) of the CPSA in a notice published in the Federal Register on February 9, 2009 (74 FR 6396... December 28, 2009, the Commission published a notice in the Federal Register (74 FR 68588) revising the... COMMISSION 16 CFR Part 1216 Third Party Testing for Certain Children's Products; Infant Walkers:...

  7. 75 FR 24753 - The Walker Auto Group, Inc., Miamisburg, OH; Notice of Negative Determination Regarding...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ... Employment and Training Administration The Walker Auto Group, Inc., Miamisburg, OH; Notice of Negative... the State of Ohio requested administrative reconsideration of the Department's negative determination... workers of the subject firm. The negative determination was signed on January 8, 2010. The...

  8. Promoting Ambulation Responses among Children with Multiple Disabilities through Walkers and Microswitches with Contingent Stimuli

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Oliva, Doretta; Smaldone, Angela; La Martire, Maria L.; Stasolla, Fabrizio; Castagnaro, Francesca; Groeneweg, Jop

    2010-01-01

    Children with severe or profound intellectual and motor disabilities often present problems of balance and ambulation and spend much of their time sitting or lying, with negative consequences for their development and social status. Recent research has shown the possibility of using a walker (support) device and microswitches with preferred…

  9. An Open Letter to Suzanne deCastell and Tom Walker.

    ERIC Educational Resources Information Center

    Assinck, Beverly Belvin

    1993-01-01

    Responds to "Identity, Metamorphosis, and Ethnographic Research: What Kind of Story Is Ways with Words?" by Suzanne deCastell and Tom Walker (1991). Describes the author's reaction to "Ways with Words--Language, Life and Work in Communities and Classrooms" by Shirley Brice Heath (1983). (SLD)

  10. Origin of the Pinenuts and Other Stories from the Walker River Paiute Reservation.

    ERIC Educational Resources Information Center

    George, Wuzzie; And Others

    The four stories gathered from Paiute Tribal Elders through the Ethnic Heritage Studies Program have been changed from the original telling insofar as it was necessary to make them suitable to the elementary level. The short stories, meant to be spoken orally, relate how the Walker Lake Paiutes got pinenuts away from the Owyhee area ("Origin of…

  11. A Linguistic Analysis of Rhetorical Strategies in Selected Narratives of Alice Walker

    ERIC Educational Resources Information Center

    Matunda, Robert Stephen Mokaya

    2009-01-01

    The objective of this investigation was to analyze rhetorical strategies of Alice Walker in four narratives, namely, "The Color Purple, In Search of Our Mother's Gardens, Possessing the Secret of Joy, and Now Is the Time To Open Your Heart". As such, this study helps to expand the body of investigation relating linguistics to literature and medium…

  12. A systematic study of Ichneumonosoma Meijere, Pelmatops Enderlein, Pseudopelmatops Shiraki and Soita Walker (Diptera: Tephritidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four fruit fly genera, Ichneumonosoma Meijere, Pelmatops Enderlein, Pseudopelmatops Shiraki and Soita Walker, were studied and 19 species are recognized. Three new species, S. infuscata Chen et Norrbom n. sp., I. quadripunctata Chen et Freidberg, n. sp. and I. triangularis Chen et Norrbom, n. sp. ar...

  13. Sex Differences in Moral Reasoning: Response to Walker's (1984) Conclusion That There Are None.

    ERIC Educational Resources Information Center

    Baumrind, Diana

    1986-01-01

    Takes issue with Lawrence Walker's literature review on developmental and individual differences in moral reasoning which found no consistent evidence for sex differences in moral development. Argues instead that the source and specific nature of these differences have yet to be established. (HOD)

  14. The Legal Dimension of RTI--Confusion Confirmed: A Response to Walker and Daves

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2012-01-01

    In this issue of "Learning Disability Quarterly" (LDQ), Professors Daves and Walker reply to my earlier LDQ article on confusion in the cases and commentary about the legal dimension of RTI. In this brief rejoinder, I show that their reply confirms rather than resolves the confusion in their original commentary in 2010. This persistent problem…

  15. Writing a Rationale for a Controversial Common Reading Book: Alice Walker's "The Color Purple."

    ERIC Educational Resources Information Center

    Worthington, Pepper

    1985-01-01

    Offers a rationale that can be used to defend the assignment of Alice Walker's controversial novel for class reading. Indicates four issues that might evoke calls for censorship: (1) subject matter, (2) vocabulary, (3) grammar, and (4) the epistolary form of the work. (RBW)

  16. Black Matrilineage: The Case of Alice Walker and Zora Neale Hurston.

    ERIC Educational Resources Information Center

    Sadoff, Diane F.

    1985-01-01

    Discusses the relationship of the Black contemporary author, Alice Walker, to folklorist Zora Neale Hurston and presents a clarification of the relationship of gender and race in a revised theory of literary influence. Argues that Black women authors sometimes misread literary forbears in order to discover and express a positive matrilineage…

  17. If the Song Sounds the Same Check for Static: A Reply to Walker and Frimer

    ERIC Educational Resources Information Center

    Sherblom, Stephen A.

    2009-01-01

    The "care challenge" is shown to be both broader and more successful than Walker and Frimer's (this issue, pp. 53-68) critique allows. The main philosophical and psychological tenets of the care challenge foreshadowed the direction of twenty-first century moral psychology.

  18. A New Controller for a Smart Walker Based on Human-Robot Formation

    PubMed Central

    Valadão, Carlos; Caldeira, Eliete; Bastos-Filho, Teodiano; Frizera-Neto, Anselmo; Carelli, Ricardo

    2016-01-01

    This paper presents the development of a smart walker that uses a formation controller in its displacements. Encoders, a laser range finder and ultrasound are the sensors used in the walker. The control actions are based on the user (human) location, who is the actual formation leader. There is neither a sensor attached to the user’s body nor force sensors attached to the arm supports of the walker, and thus, the control algorithm projects the measurements taken from the laser sensor into the user reference and, then, calculates the linear and angular walker’s velocity to keep the formation (distance and angle) in relation to the user. An algorithm was developed to detect the user’s legs, whose distances from the laser sensor provide the information necessary to the controller. The controller was theoretically analyzed regarding its stability, simulated and validated with real users, showing accurate performance in all experiments. In addition, safety rules are used to check both the user and the device conditions, in order to guarantee that the user will not have any risks when using the smart walker. The applicability of this device is for helping people with lower limb mobility impairments. PMID:27447634

  19. Seeing the Sky through Hubble's Eye: The COSMOS SkyWalker

    NASA Astrophysics Data System (ADS)

    Jahnke, K.; Sánchez, S. F.; Koekemoer, A.

    2006-08-01

    Large, high-resolution space-based imaging surveys produce a volume of data that is difficult to present to the public in a comprehensible way. While megapixel-sized images can still be printed out or downloaded via the World Wide Web, this is no longer feasible for images with 109 pixels (e.g., the Hubble Space Telescope Advanced Camera for Surveys [ACS] images of the Galaxy Evolution from Morphology and SEDs [GEMS] project) or even 1010 pixels (for the ACS Cosmic Evolution Survey [COSMOS]). We present a Web-based utility called the COSMOS SkyWalker that allows viewing of the huge ACS image data set, even through slow Internet connections. Using standard HTML and JavaScript, the application successively loads only those portions of the image at a time that are currently being viewed on the screen. The user can move within the image by using the mouse or interacting with an overview image. Using an astrometrically registered image for the COSMOS SkyWalker allows the display of calibrated world coordinates for use in science. The SkyWalker ``technique'' can be applied to other data sets. This requires some customization, notably the slicing up of a data set into small (e.g., 2562 pixel) subimages. An advantage of the SkyWalker is the use of standard Web browser components; thus, it requires no installation of any software and can therefore be viewed by anyone across many operating systems.

  20. Walker Diffusion Method for Calculation of Transport Properties of Finite Composite Systems

    SciTech Connect

    Van Siclen, Clinton D

    2002-01-01

    A heterogeneous medium may be represented by a scalar field of local transport coefficients (e.g., conductivity) or by a “resistor network” derived from that scalar field. In either case the effective (macroscopic) and local (microscopic) transport properties may be calculated by the walker diffusion method. Some sample calculations for disordered systems are presented to demonstrate the method.

  1. A Noncomputerized Version of the Williams and Walker Stock Market Experiment in a Finance Course.

    ERIC Educational Resources Information Center

    Bell, Christopher R.

    1993-01-01

    Asserts that the computerized stock market simulation described by Williams and Walker is complex and a better approach to teaching financial economics. Describes a noncomputerized version of the same teaching activity used to teach asset valuation to undergraduate financial economics students. (CFR)

  2. Partial albinism, immunodeficiency, hypergammaglobulinemia and Dandy-Walker cyst--a Griscelli syndrome variant.

    PubMed

    Dinakar, Chitra; Lewin, S; Kumar, Karuna R; Harshad, Sujatha R

    2003-10-01

    A 6-year-old girl presented with recurrent infections, seizures, regression of milestones, silvery hair and organomegaly. A diagnosis of Griscelli syndrome with unusual features of a Dandy Walker cyst and hypergammaglobulinemia, not previously described in literature, was made. The child was treated with supportive measures. PMID:14581742

  3. Slowdown of the Walker circulation driven by tropical Indo-Pacific warming.

    PubMed

    Tokinaga, Hiroki; Xie, Shang-Ping; Deser, Clara; Kosaka, Yu; Okumura, Yuko M

    2012-11-15

    Global mean sea surface temperature (SST) has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of SST warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes.

  4. Collateral Damage: Veterans and Domestic Violence in Mari Sandoz's "The Tom-Walker"

    ERIC Educational Resources Information Center

    Bahr, Kathy

    2010-01-01

    "The Tom-Walker" combines the best of Sandoz's realism with her worst attempts at moralizing. Unable to divine exactly what political configuration right-wing post-World War II sentiments might take, Sandoz nevertheless feared a fascist uprising in this country. Perhaps because these concerns dominated her thoughts at the time, she allowed her…

  5. Statement of Facts for 1977 City-Wide Mock Trial Competitions. Walker Thomas v. Sam Nomad.

    ERIC Educational Resources Information Center

    National Inst. for Citizen Education in the Law, Washington, DC.

    Prepared by the District of Columbia Street Law Project for its annual city-wide mock trial competition, this instructional handout provides material for a civil case over an automobile accident. Walker Thomas is suing Sam Nomad for damages that resulted from a collision, for which both parties blame the other. The handout clarifies the laws and…

  6. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section 890.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790...

  7. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section 890.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790...

  8. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section 890.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790...

  9. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section 890.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790...

  10. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section 890.3790 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790...

  11. Spatially-Hyperbolic Friedmann-Robertson-Walker Universe with Potentially Broken Z 2-Symmetry

    NASA Astrophysics Data System (ADS)

    Dariescu, Ciprian; Bodnarescu, Adrian; Dariescu, Marina-Aura

    2016-09-01

    For the Friedmann-Robertson-Walker (FRW) Universe with negative curvature, sustained by a spontaneous Z 2- symmetry breaking scalar field, depending on time alone, we have derived the Einstein-Gordon system of equations. For physically relevant cases, the matter-curvature system have been numerically analyzed.

  12. Description of three new species of Arescon Walker (Hymenoptera, Mymaridae) from China

    PubMed Central

    Jin, Xiang-Xiang; Li, Cheng-De; Yang, Jian-Chun

    2016-01-01

    Abstract Three new species of Arescon Walker, 1846, Arescon gaoligongensis Jin & Li, sp. n., Arescon sparsiciliatus Jin & Li, sp. n. and Arescon stenopterus Jin & Li, sp. n. are described. A key to the Chinese species is given and photomicrographs are provided to illustrate morphological characters. All the specimens are deposited in the insect collections of Northeast Forestry University, China. PMID:27199596

  13. Slowdown of the Walker circulation driven by tropical Indo-Pacific warming.

    PubMed

    Tokinaga, Hiroki; Xie, Shang-Ping; Deser, Clara; Kosaka, Yu; Okumura, Yuko M

    2012-11-15

    Global mean sea surface temperature (SST) has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of SST warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that SST warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The SST trend reconstructed from bucket-sampled SST and night-time marine surface air temperature features a reduced zonal gradient in the tropical Indo-Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes. PMID:23151588

  14. 78 FR 25234 - Proposed Establishment of Class E Airspace; Walker, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-30

    ... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... read as follows: Authority: 49 U.S.C. 106(g); 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959... Federal Aviation Administration 14 CFR Part 71 Proposed Establishment of Class E Airspace; Walker,...

  15. A gait stability investigation into FES-assisted paraplegic walking based on the walker tipping index

    NASA Astrophysics Data System (ADS)

    Ming, Dong; Bai, Yanru; Liu, Xiuyun; Qi, Hongzhi; Cheng, Longlong; Wan, Baikun; Hu, Yong; Wong, Yatwa; Luk, Keith D. K.; Leong, John C. Y.

    2009-12-01

    The gait outcome measures used in clinical trials of paraplegic locomotor training determine the effectiveness of improved walking function assisted by the functional electrical stimulation (FES) system. Focused on kinematic, kinetic or physiological changes of paraplegic patients, traditional methods cannot quantify the walking stability or identify the unstable factors of gait in real time. Up until now, the published studies on dynamic gait stability for the effective use of FES have been limited. In this paper, the walker tipping index (WTI) was used to analyze and process gait stability in FES-assisted paraplegic walking. The main instrument was a specialized walker dynamometer system based on a multi-channel strain-gauge bridge network fixed on the frame of the walker. This system collected force information for the handle reaction vector between the patient's upper extremities and the walker during the walking process; the information was then converted into walker tipping index data, which is an evaluation indicator of the patient's walking stability. To demonstrate the potential usefulness of WTI in gait analysis, a preliminary clinical trial was conducted with seven paraplegic patients who were undergoing FES-assisted walking training and seven normal control subjects. The gait stability levels were quantified for these patients under different stimulation patterns and controls under normal walking with knee-immobilization through WTI analysis. The results showed that the walking stability in the FES-assisted paraplegic group was worse than that in the control subject group, with the primary concern being in the anterior-posterior plane. This new technique is practical for distinguishing useful gait information from the viewpoint of stability, and may be further applied in FES-assisted paraplegic walking rehabilitation.

  16. Extraction of user's navigation commands from upper body force interaction in walker assisted gait

    PubMed Central

    2010-01-01

    Background The advances in technology make possible the incorporation of sensors and actuators in rollators, building safer robots and extending the use of walkers to a more diverse population. This paper presents a new method for the extraction of navigation related components from upper-body force interaction data in walker assisted gait. A filtering architecture is designed to cancel: (i) the high-frequency noise caused by vibrations on the walker's structure due to irregularities on the terrain or walker's wheels and (ii) the cadence related force components caused by user's trunk oscillations during gait. As a result, a third component related to user's navigation commands is distinguished. Results For the cancelation of high-frequency noise, a Benedict-Bordner g-h filter was designed presenting very low values for Kinematic Tracking Error ((2.035 ± 0.358)·10-2 kgf) and delay ((1.897 ± 0.3697)·101ms). A Fourier Linear Combiner filtering architecture was implemented for the adaptive attenuation of about 80% of the cadence related components' energy from force data. This was done without compromising the information contained in the frequencies close to such notch filters. Conclusions The presented methodology offers an effective cancelation of the undesired components from force data, allowing the system to extract in real-time voluntary user's navigation commands. Based on this real-time identification of voluntary user's commands, a classical approach to the control architecture of the robotic walker is being developed, in order to obtain stable and safe user assisted locomotion. PMID:20687921

  17. Active transtensional intracontinental basins: Walker Lane in the western Great Basin

    USGS Publications Warehouse

    Jayko, Angela S.; Bursik, Marcus

    2012-01-01

    The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and adjacent basins are filled or poorly developed. To the south, the basin sizes are moderate, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ∼85-100km wide, where the basins are elongated E-W to ENE, small (∼15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ∼5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

  18. Obituary: Alastair Graham Walker Cameron, 1925-2005

    NASA Astrophysics Data System (ADS)

    Truran, James W.; Thielemann, F.-K.; Cowan, J. J.

    2005-12-01

    Alastair Graham Walker Cameron, one of the most creative and influential astrophysicists of his generation, passed away on 3 October 2005, at the age of 80, at his home in Tucson. Subsequent to his retirement from Harvard University, where he had been a member of the faculty from 1973 through 1999, Cameron remained active as a Senior Research Scientist at the Lunar and Planetary Laboratory of the University of Arizona. Cameron had a distinguished career during which he made outstanding contributions both in scientific research and in public service to science. Notable among the latter are the years he spent as Chairman of the Space Science Board of the National Academy of Sciences from 1976 to 1982. He was a member of the National Academy of Sciences and the recipient of a number of awards for his diverse contributions to the sciences, including the J. Lawrence Smith Medal of the National Academy of Sciences in 1988, the Leonard Medal of the American Meteoritical Society in 1994, the Henry Norris Russell Lectureship of the American Astronomical Society in 1997, and the Hans A. Bethe prize of the Division of Nuclear Physics of the American Physical Society for 2006, for outstanding work in nuclear physics and astrophysics. He was enormously active in the organization of conferences and workshops and in an editorial capacity, for a number of journals in astronomy, astrophysics, and space physics. Over the course of his career, he made seminal contributions to such diverse areas of astronomical and astrophysical research as nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, meteoritics, stellar evolution, neutron stars, the origin of the Solar System, the physics of planets and planetary atmospheres, and the origin of the Moon. Born on 21 June 1925 in Winnipeg, Manitoba, Cameron received his undergraduate degree from the University of Manitoba and his doctorate in nuclear physics from the University of Saskatchewan in 1952

  19. Obituary: Richard L. (Dick) Walker, Jr., 1938-2005

    NASA Astrophysics Data System (ADS)

    Pier, Jeffrey R.; Mason, Brian

    2005-12-01

    Dick Walker, 67, died 30 March 2005 in Flagstaff, AZ, following a long illness. He was born on 9 March 1938 in Hampton, Iowa and grew up in Waterloo, Iowa. As a child, Dick was fascinated with astronomy and built his own telescope. He saved his pennies and bought and read every book on the subject he could find. He also raised pigeons, naming four of them Hertzsprung, Hoyle, Gamow, and Kron. In 1957, the year Sputnik was launched, Dick began his college studies at the University of Northern Iowa in Cedar Falls. In 1959, he transferred to the State University of Iowa (subsequently renamed the University of Iowa) in Iowa City, where he earned a BA degree in astronomy and physics in 1963. He joined the staff of the U.S. Naval Observatory in Washington, DC, where he worked in the Time Service Division for a year before his assignment to the Astrometry and Astrophysics Division. Dick relocated to Flagstaff, AZ, in 1966 to continue his Naval Observatory service at the Flagstaff Station. His retirement in May 1999, ended a thirty-six-year career with USNO. Dick was first and foremost an observational astronomer. From the mid 1960s through the late 1970s, much of Dick's time was devoted to the measurement of binary stars, observing with the 12-inch and 26-inch refractors in Washington and later the 40-inch and 61-inch reflectors in Flagstaff. He also made many trips to Lick Observatory to work with the 36-inch Clark Refractor there. During this time he consulted with Charles Worley, who was observing on the 26-inch, to make sure time was well-spent examining doubles that could not be observed in Washington. This period of observing overlapped with the early years of speckle interferometry, and Dick's observations, made with the largest telescope used for micrometry at the time, were very important for ascertaining the veracity of this new technique. He was a studious and very careful observer of doubles and made over 8,000 measures, resulting in almost 3,000 mean positions

  20. Influence of an infant walker on onset and quality of walking pattern of locomotion:an electromyographic investigation.

    PubMed

    Kauffman, I B; Ridenour, M

    1977-12-01

    Acquisition of bipedal locomotor skill in human infants was studied electromyographically with regard to the deprivation or enrichment behavior resulting from the frequent and regular use of an infant walker. Subjects were six sets of male, fraternal twins. One randomly selected sibling from each set underwent a training program, commencing at the age of 300 days, spending a total of 2 hr. per day in a walker. Siblings not included in this group were subjected to no special training. EMG recordings were taken of all subjects at specified intervals in order to establish a model of the typical motor pattern at various stages of skill development. These data were then contrasted with EMG data similarly obtained from the walker-trained subjects. Use of an infant walker modified the mechanics of the infant's locomotion in a number of important ways. It was shown that use of the walker enables an infant to commit substantial mechanical errors yet succeed in bipedal locomotion. Inasmuch as the mechanics of walker-assisted and non-assisted bipedal locomotion are dissimilar in so many important ways, positive transfer from walker-training appears questionable.

  1. Theoretical optimization of usage of four-wheeled walker and body posture of elderly users for comfortable steady walking.

    PubMed

    Takanokura, Masato

    2008-01-01

    Usage of a four-wheeled walker and body posture of elderly users is optimized by a two-dimensional statics model for comfortable steady walking. Analytical results suggest that fundamentals of body posture for comfortable walking should be as upright as possible. However, usage of the walker varies with exercise capabilities of elderly users. Users with high capabilities should use a higher handgrip for maintaining upright posture. Stooping users with low capabilities should use a lower handgrip, should maintain an erect trunk as much as possible, and should push the handgrip downward by leaning their upper body on the walker.

  2. The contribution of Dr. Mary Walker towards myasthenia gravis and periodic paralysis whilst working in poor law hospitals in London.

    PubMed

    Johnston, J D

    2005-06-01

    Dr. Mary Walker discovered in 1934 that physostigmine and Prostigmin temporarily restored muscle function in patients with myasthenia gravis. In the next five years, Dr. Walker and colleagues provided clinical evidence for the weakness of myasthenia gravis being caused by a "disturbance of transmission of excitation from motor nerve to voluntary muscle presumably caused by a deficiency of acetylcholine. Physostigmine (or Prostigmin) compensated for the lack of acetylcholine by delaying its destruction." Dr. Walker and colleagues also described the association between familial periodic paralysis and hypokalaemia.

  3. 75 FR 19880 - Safety Zone; BW PIONEER at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... PIONEER at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico in the Federal Register (74 FR...-2103, madeleine.w.mcnamara@uscg.mil . If you have questions on viewing the docket, call Renee V....

  4. Energy cost of paraplegic locomotion with the ORLAU ParaWalker.

    PubMed

    Nene, A V; Patrick, J H

    1989-02-01

    Ten subjects with neurological lesion levels between T4 and T9 have been evaluated in the laboratory at ORLAU using their orthosis in its mechanical form alone (without FES assist). Initially the oxygen consumption at rest was measured. Then the patients were asked to walk (orthotic gait) at their preferred constant steady speed for a period of 5 minutes. Min. VO2 was measured during the exercise. From these readings the energy cost and consumption of the patients' gait was calculated. Our results show that the ParaWalker allows more efficient walking than do bilateral long leg braces and a paraplegic 3 point gait. It also shows that higher speeds with lower energy cost walking is possible with a different orthotic approach for high or mid thoracic lesion paraplegics. We believe that the energy demands to walk with the ParaWalker are within sustainable limits.

  5. Birth of a fault: Connecting the Kern County and Walker Pass, California, earthquakes

    USGS Publications Warehouse

    Bawden, G.W.; Michael, A.J.; Kellogg, L.H.

    1999-01-01

    A band of seismicity transects the southern Sierra Nevada range between the northeastern end of the site of the 1952 MW (moment magnitude) 7.3 Kern County earthquake and the site of the 1946 MW 6.1 Walker Pass earthquake. Relocated earthquakes in this band, which lacks a surface expression, better delineate the northeast-trending seismic lineament and resolve complex structure near the Walker Pass mainshock. Left-lateral earthquake focal planes are rotated counterclockwise from the strike of the seismic lineament, consistent with slip on shear fractures such as those observed in the early stages of fault development in laboratory experiments. We interpret this seismic lineament as a previously unrecognized, incipient, currently blind, strike-slip fault, a unique example of a newly forming structure.

  6. Sex differences in moral reasoning: response to Walker's (1984) conclusion that there are none.

    PubMed

    Baumrind, D

    1986-04-01

    Data from the Family Socialization and Developmental Competence Project are used to probe Walker's conclusion that there are no sex differences in moral reasoning. Ordinal and nominal nonparametric statistics result in a complex but theoretically meaningful network of relationships among sex, educational level, and Kohlberg stage score level, with the presence and direction of sex differences in stage score level dependent on educational level. The effects on stage score level of educational level and working status are also shown to differ for men and women. Reasons are considered for not accepting Walker's dismissal of studies that use (a) a pre-1983 scoring manual, or (b) fail to control for education. The problems presented to Kohlberg's theory by the significant relationship between educational and stage score levels in the general population are discussed, particularly as these apply to the postconventional level of moral reasoning.

  7. Finite difference method to find period-one gait cycles of simple passive walkers

    NASA Astrophysics Data System (ADS)

    Dardel, Morteza; Safartoobi, Masoumeh; Pashaei, Mohammad Hadi; Ghasemi, Mohammad Hassan; Navaei, Mostafa Kazemi

    2015-01-01

    Passive dynamic walking refers to a class of bipedal robots that can walk down an incline with no actuation or control input. These bipeds are sensitive to initial conditions due to their style of walking. According to small basin of attraction of passive limit cycles, it is important to start with an initial condition in the basin of attraction of stable walking (limit cycle). This paper presents a study of the simplest passive walker with point and curved feet. A new approach is proposed to find proper initial conditions for a pair of stable and unstable period-one gait limit cycles. This methodology is based on finite difference method which can solve the nonlinear differential equations of motion on a discrete time. Also, to investigate the physical configurations of the walkers and the environmental influence such as the slope angle, the parameter analysis is applied. Numerical simulations reveal the performance of the presented method in finding two stable and unstable gait patterns.

  8. Sedimentary biomarker and isotopic indicators of the paleoclimatic history of the Walker Lake basin, western Nevada

    USGS Publications Warehouse

    Meyers, P.A.; Benson, L.V.

    1988-01-01

    Walker Lake, a terminal saline lake in western Nevada, has experienced major fluctuations in its water level due to changes in the regional climate during Quaternary times. As part of a paleo-climatological study of western Nevada, we have investigated organic matter ??13C and C/N values and lipid biomarker contents of sediments deposited at various periods over the past 150 thousand years of lake history. Surficial sediments from two cross-lake transects contain mostly lake-derived organic matter. Diagenetic losses of organic matter are evident in deeper sediments, and the proportion of aquatic and terrigenous organic materials changes in response to variations in preservational factors. Source identification of organic matter is complicated by the probability that Walker Lake has experienced desiccation at various times in its history which impacts the degree of preservation of organic substances. ?? 1988.

  9. Jamming and Attraction of Interacting Run-and-Tumble Random Walkers

    NASA Astrophysics Data System (ADS)

    Slowman, A. B.; Evans, M. R.; Blythe, R. A.

    2016-05-01

    We study a model of bacterial dynamics where two interacting random walkers perform run-and-tumble motion on a one-dimensional lattice under mutual exclusion and find an exact expression for the probability distribution in the steady state. This stationary distribution has a rich structure comprising three components: a jammed component, where the particles are adjacent and block each other; an attractive component, where the probability distribution for the distance between particles decays exponentially; and an extended component in which the distance between particles is uniformly distributed. The attraction between the particles is sufficiently strong that even in the limit where continuous space is recovered for a finite system, the two walkers spend a finite fraction of time in a jammed configuration. Our results potentially provide a route to understanding the motility-induced phase separation characteristic of active matter from a microscopic perspective.

  10. Jamming and Attraction of Interacting Run-and-Tumble Random Walkers.

    PubMed

    Slowman, A B; Evans, M R; Blythe, R A

    2016-05-27

    We study a model of bacterial dynamics where two interacting random walkers perform run-and-tumble motion on a one-dimensional lattice under mutual exclusion and find an exact expression for the probability distribution in the steady state. This stationary distribution has a rich structure comprising three components: a jammed component, where the particles are adjacent and block each other; an attractive component, where the probability distribution for the distance between particles decays exponentially; and an extended component in which the distance between particles is uniformly distributed. The attraction between the particles is sufficiently strong that even in the limit where continuous space is recovered for a finite system, the two walkers spend a finite fraction of time in a jammed configuration. Our results potentially provide a route to understanding the motility-induced phase separation characteristic of active matter from a microscopic perspective. PMID:27284675

  11. Design and control of a two-wheeled robotic walker for balance enhancement.

    PubMed

    da Silva, Airton R; Sup, Frank

    2013-06-01

    This paper presents the preliminary design results and control strategy of a two-wheeled inverted pendulum (TWIP) robotic walker for assisting mobility-impaired users with balance and stability. A conceptual model of the vehicle is developed and used to illustrate the purpose of this study. Motor dynamics is considered and the linearized equations of motion for the system are derived using Newtonian mechanics. In order to eliminate the effects of loop interaction and impose the desired dynamics on the system, a decoupling control scheme was implemented. Upright stabilization of the robotic walker is achieved using linear quadratic regulator (LQR) control. Improved disturbance rejection is achieved through the implementation of a pitch controller. Simulation results demonstrate that a robustly tuned pitch controller can mitigate effect of disturbance on the linear displacement of the vehicle by as much as 74%.

  12. Motility of Colonial Choanoflagellates and the Statistics of Aggregate Random Walkers

    NASA Astrophysics Data System (ADS)

    Kirkegaard, Julius B.; Marron, Alan O.; Goldstein, Raymond E.

    2016-01-01

    We illuminate the nature of the three-dimensional random walks of microorganisms composed of individual organisms adhered together. Such aggregate random walkers are typified by choanoflagellates, eukaryotes that are the closest living relatives of animals. In the colony-forming species Salpingoeca rosetta we show that the beating of each flagellum is stochastic and uncorrelated with others, and the vectorial sum of the flagellar propulsion manifests as stochastic helical swimming. A quantitative theory for these results is presented and species variability discussed.

  13. The Friedmann-Lemaître-Robertson-Walker Big Bang Singularities are Well Behaved

    NASA Astrophysics Data System (ADS)

    Stoica, Ovidiu Cristinel

    2016-01-01

    We show that the Big Bang singularity of the Friedmann-Lemaître-Robertson-Walker model does not raise major problems to General Relativity. We prove a theorem showing that the Einstein equation can be written in a non-singular form, which allows the extension of the spacetime before the Big Bang. The physical interpretation of the fields used is discussed. These results follow from our research on singular semi-Riemannian geometry and singular General Relativity.

  14. Exact solutions to Elko spinors in spatially flat Friedmann-Robertson-Walker spacetimes

    SciTech Connect

    Silva, J.M. Hoff da; Pereira, S.H. E-mail: shpereira@gmail.com

    2014-03-01

    In this paper we present exact solutions to the so-called Elko spinors for three models of expanding universe, namely the de Sitter, linear and the radiation type evolution. The study was restricted to flat, homogeneous and isotropic Friedmann-Robertson-Walker backgrounds. Starting with an Elko spinor we present the solutions for these cases and compare to the case of Dirac spinors. Besides, an attempt to use Elko spinors as a dark energy candidate in the cosmological context is investigated.

  15. Women in History--Madame C. J. Walker 1867-1919

    ERIC Educational Resources Information Center

    Huber, Germaine W.

    2009-01-01

    This article profiles Madame C. J. Walker. Sarah Breedlove was born on December 23, 1867, the fifth of six children of Owen and Minerva Breedlove. Sarah was the first of the Breedlove children to be born after the end of slavery. Her parents died when she was six or seven years of age. At age fourteen she married Moses McWilliams, who also died in…

  16. Nonintegrability of density perturbations in the Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Stachowiak, Tomasz; Szydłowski, Marek; Maciejewski, Andrzej J.

    2006-03-01

    We investigate the evolution equation of linear density perturbations in the Friedmann-Robertson-Walker universe with matter, radiation and the cosmological constant. The concept of solvability by quadratures is defined and used to prove that there are no "closed form" solutions except for the known Chernin, Heath, Meszaros and simple degenerate ones. The analysis is performed applying Kovacic's algorithm. The possibility of the existence of other, more general solutions involving special functions is also investigated.

  17. A new lethal chondrodysplasia with spondylocostal dysostosis, multiple internal anomalies and Dandy-Walker cyst.

    PubMed

    Moerman, P; Vandenberghe, K; Fryns, J P; Haspeslagh, M; Lauweryns, J M

    1985-02-01

    We describe here a female infant, exhibiting lethal short-limbed dwarfism. The condition superficially resembled achondrogenesis. However, unlike achondrogenesis there was an associated severe spondylocostal dysostosis and major non-skeletal anomalies, particularly a cerebellar Dandy-Walker cyst, cardiovascular and urogenital malformations. The chondroosseous morphology was nonspecific. The case is believed to be unique. It is therefore suggested that this constellation of anomalies constitutes a "new" lethal syndrome, different from the delineated chondrodysplasias. PMID:3884191

  18. ARG-walker: inference of individual specific strengths of meiotic recombination hotspots by population genomics analysis

    PubMed Central

    2015-01-01

    Background Meiotic recombination hotspots play important roles in various aspects of genomics, but the underlying mechanisms for regulating the locations and strengths of recombination hotspots are not yet fully revealed. Most existing algorithms for estimating recombination rates from sequence polymorphism data can only output average recombination rates of a population, although there is evidence for the heterogeneity in recombination rates among individuals. For genome-wide association studies (GWAS) of recombination hotspots, an efficient algorithm that estimates the individualized strengths of recombination hotspots is highly desirable. Results In this work, we propose a novel graph mining algorithm named ARG-walker, based on random walks on ancestral recombination graphs (ARG), to estimate individual-specific recombination hotspot strengths. Extensive simulations demonstrate that ARG-walker is able to distinguish the hot allele of a recombination hotspot from the cold allele. Integrated with output of ARG-walker, we performed GWAS on the phased haplotype data of the 22 autosome chromosomes of the HapMap Asian population samples of Chinese and Japanese (JPT+CHB). Significant cis-regulatory signals have been detected, which is corroborated by the enrichment of the well-known 13-mer motif CCNCCNTNNCCNC of PRDM9 protein. Moreover, two new DNA motifs have been identified in the flanking regions of the significantly associated SNPs (single nucleotide polymorphisms), which are likely to be new cis-regulatory elements of meiotic recombination hotspots of the human genome. Conclusions Our results on both simulated and real data suggest that ARG-walker is a promising new method for estimating the individual recombination variations. In the future, it could be used to uncover the mechanisms of recombination regulation and human diseases related with recombination hotspots. PMID:26679564

  19. First report of Ricania speculum (Walker, 1851) in Europe (Hemiptera: Fulgoromorpha: Ricaniidae).

    PubMed

    Mazza, Giuseppe; Pennacchio, Fabrizio; Gargani, Elisabetta; Franceschini, Italo; Roversi, Pio Federico; Cianferoni, Fabio

    2014-09-15

    Ricania speculum (Walker, 1851) (Hemiptera: Fulgoromorpha: Ricaniidae) is reported for the first time in Europe. Both nymphs and adults were observed from 2009 in several municipalities of Liguria (Italy). Since the species is extremely polyphagous and is a real pest for several crops in tropical and subtropical areas, the presence of this alien insect is noteworthy, representing a new possible threat for native species and human activities. 

  20. The Cooper River Bridge Run Study of low back pain in runners and walkers.

    PubMed

    Woolf, Shane K; Barfield, William R; Nietert, Paul J; Mainous, Arch G; Glaser, John A

    2002-01-01

    Investigations dedicated to examining relationships between low back pain (LBP) and factors specific to running and walking are limited. Current literature suggests runners and walkers may have a lower relative risk for significant LBP. The purpose of this study was to investigate the incidence, prevalence, and possible risk factors for LBP among a group of runners and walkers. A survey was administered to participants who registered for either a 10-kilometer run or 4-mile recreational walk. A total of 539 responses were received. Previous history of LBP was reported by 74% of respondents overall. Prevalence of LBP at the time of survey completion was 13.6%. Low back pain was experienced more frequently by obese runners and by those who reported certain patterns of shoe wear. Regular participation in aerobics correlated with a reduced lifetime risk for LBP. We believe these findings warrant further investigation. This knowledge may benefit not only athletes in training, but other fitness enthusiasts, including casual runners and walkers and those who jog or walk to rehabilitate low back injuries.

  1. Dynamic optimization of walker-assisted FES-activated paraplegic walking: simulation and experimental studies.

    PubMed

    Nekoukar, Vahab; Erfanian, Abbas

    2013-11-01

    In this paper, we propose a musculoskeletal model of walker-assisted FES-activated paraplegic walking for the generation of muscle stimulation patterns and characterization of the causal relationships between muscle excitations, multi-joint movement, and handle reaction force (HRF). The model consists of the lower extremities, trunk, hands, and a walker. The simulation of walking is performed using particle swarm optimization to minimize the tracking errors from the desired trajectories for the lower extremity joints, to reduce the stimulations of the muscle groups acting around the hip, knee, and ankle joints, and to minimize the HRF. The results of the simulation studies using data recorded from healthy subjects performing walker-assisted walking indicate that the model-generated muscle stimulation patterns are in agreement with the EMG patterns that have been reported in the literature. The experimental results on two paraplegic subjects demonstrate that the proposed methodology can improve walking performance, reduce HRF, and increase walking speed when compared to the conventional FES-activated paraplegic walking.

  2. Mechanical energy flow in the recovery leg of elite race walkers.

    PubMed

    Hoga, Koji; Ae, Michiyoshi; Enomoto, Yasushi; Fujii, Norihisa

    2003-01-01

    The purpose of this study was to investigate the mechanical energy flow in the recovery leg and its relationship to performance descriptors of elite male race walkers in an official race. Male race walkers participating in official 20 km races were videotaped with a VTR camera (60 Hz) set perpendicular to the course. The 28 elite race walkers (race records 1:19'50"-1:33'58") were selected as subjects. A two dimensional 14-segment linked model was used to calculate biomechanical parameters from the walking motion in the early phase of the race. The walking speed was significantly related to the step length but not related to the step frequency. Large mechanical energy flows at the hip occurred from the trunk to the foot during the first half of the recovery phase and from the foot to the trunk during the second half by the joint force power. Joint force powers at the hip in the second half of the recovery phase were significantly related to the walking speed and the step length. It is suggested that large joint force power at the hip would be one of the important factors to obtain high walking speed.

  3. Joint torque and mechanical energy flow in the support legs of skilled race walkers.

    PubMed

    Hoga, Koji; Ae, Michiyoshi; Enomoto, Yasushi; Yokozawa, Toshiharu; Fujii, Norihisa

    2006-07-01

    This study analyzed the joint torque and the mechanical energy flow in the support legs of skilled male race walkers. Twelve race walkers were videotaped using a high-speed camera at a frame rate of 250 Hz set perpendicular to the sagittal plane of motion; their ground reaction forces were measured with two force platforms. A two-dimensional, 14-segment, linked model was used to calculate the kinetics of the support leg joints. In the initial part of the support phase, the mechanical energy flowed into the thigh and shank by the torque of the large hip extensors and knee flexors. In the middle part, the mechanical energy generated by the torque of the large plantar flexors flowed to the foot and from the foot to the shank by the ankle joint force. The mechanical energy flow by the forward joint force of the support hip was significantly related to the walking speed in the final part of the support phase. Our findings suggest that race walkers in the final part of the support phase should exert the torque of the knee extensors and hip flexors to transfer the mechanical energy more effectively to the support thigh and shank.

  4. Acid mine drainage on public and private lands, the Walker Mine experience, Plumas County, California

    SciTech Connect

    Croyle, W.A.; Rosenbaum, S.E.

    1996-11-01

    A widespread environmental problem associated with abandoned mines and their tailings is acid mine drainage (AMD). AMID typically has low pH and elevated metal concentrations that are toxic to aquatic life. In Northern California, Iron Mountain and other mines in the Shasta mining districts are the largest sources of AMD. Additional sources lie to the south along a discontinuous belt of copper and zinc mineralization in the western Sierra foothills. Between these areas lies a remote group of copper mines in northeastern Plumas County including the Walker, Engels and Superior mines. Of this group, AMD from Walker Mine has caused the most severe water quality impairment. This paper describes the history and environmental setting of Walker Mine and the approaches used by the Central Valley Regional Water Quality Control Board, a state regulatory agency, to improve water quality at the site. Both the mine and its tailings contribute pollutants to the watershed. The mine has a portal discharge with depressed pH and high copper concentrations. The tailings add fine grained sediment to the creek and generate low but significant concentrations of dissolved copper. The mine is on private property and the tailings are on land managed by the U. S. Forest Service. Because of these differences in pollution problems and ownership, the methods employed by the Regional Board to improve conditions at the mine and tailings have been on different, but parallel tracks. Monitoring shows these efforts have significantly improved water quality in the watershed over the last 10 years.

  5. Equatorial Pacific Coral Geochemical Records Show Recent Weakening of the Walker Circulation

    NASA Astrophysics Data System (ADS)

    Carilli, J.; Mcgregor, H. V.; Gaudry, J. J.; Donner, S. D.; Gagan, M. K.; Stevenson, S. L.; Wong, H.; Fink, D.

    2014-12-01

    Equatorial Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late 20th century. We present new records of SST and sea surface salinity (SSS) spanning 1959-2010 based on paired measurements of Sr/Ca and d18O in a massive Porites coral from Butaritari atoll in the Gilbert Islands, Republic of Kiribati, in the central-western equatorial Pacific. The records show 2-7 year variability correlated with the El Niño-Southern Oscillation (ENSO) and corresponding shifts in the extent of the Indo-Pacific Warm Pool, and decadal-scale signals related to the Pacific Decadal Oscillation. In addition, the Butaritari coral records reveal a small but significant increase in SST (0.39˚C) from 1959 to 2010 with no accompanying change in SSS, a trend that persists even when ENSO variability is removed. In contrast, larger increases in SST and SSS are evident in coral records from the equatorial Pacific Line Islands, located east of Butaritari. Taken together, the equatorial Pacific coral records suggest an overall reduction in the east-west SST and SSS gradient over the last several decades, and a recent weakening of the Walker Circulation.

  6. Equatorial Pacific coral geochemical records show recent weakening of the Walker Circulation

    NASA Astrophysics Data System (ADS)

    Carilli, Jessica E.; McGregor, Helen V.; Gaudry, Jessica J.; Donner, Simon D.; Gagan, Michael K.; Stevenson, Samantha; Wong, Henri; Fink, David

    2014-11-01

    Equatorial Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late twentieth century. We present new records of SST and sea surface salinity (SSS) spanning 1959-2010 based on paired measurements of Sr/Ca and δ18O in a massive Porites coral from Butaritari atoll in the Gilbert Islands, Republic of Kiribati, in the central western equatorial Pacific. The records show 2-7 year variability correlated with the El Niño-Southern Oscillation (ENSO) and corresponding shifts in the extent of the Indo-Pacific Warm Pool, and decadal-scale signals related to the Pacific Decadal Oscillation and the Pacific Warm Pool Index. In addition, the Butaritari coral records reveal a small but significant increase in SST (0.39°C) from 1959 to 2010 with no accompanying change in SSS, a trend that persists even when ENSO variability is removed. In contrast, larger increases in SST and SSS are evident in coral records from the equatorial Pacific Line Islands, located east of Butaritari. Taken together, the equatorial Pacific coral records suggest an overall reduction in the east-west SST and SSS gradient over the last several decades, and a recent weakening of the Walker Circulation.

  7. Two-walker discrete-time quantum walks on the line with percolation.

    PubMed

    Rigovacca, L; Di Franco, C

    2016-01-01

    One goal in the quantum-walk research is the exploitation of the intrinsic quantum nature of multiple walkers, in order to achieve the full computational power of the model. Here we study the behaviour of two non-interacting particles performing a quantum walk on the line when the possibility of lattice imperfections, in the form of missing links, is considered. We investigate two regimes, statical and dynamical percolation, that correspond to different time scales for the imperfections evolution with respect to the quantum-walk one. By studying the qualitative behaviour of three two-particle quantities for different probabilities of having missing bonds, we argue that the chosen symmetry under particle-exchange of the input state strongly affects the output of the walk, even in noisy and highly non-ideal regimes. We provide evidence against the possibility of gathering information about the walkers indistinguishability from the observation of bunching phenomena in the output distribution, in all those situations that require a comparison between averaged quantities. Although the spread of the walk is not substantially changed by the addition of a second particle, we show that the presence of multiple walkers can be beneficial for a procedure to estimate the probability of having a broken link. PMID:26912102

  8. A coupled theory of tropical climatology: Warm pool, cold tongue, and Walker circulation

    SciTech Connect

    Zhengyu Liu; Boyin Huang

    1997-07-01

    Based on results from analytic and general circulation models, the authors propose a theory for the coupled warm pool, cold tongue, and Walker circulation system. The intensity of the coupled system is determined by the coupling strength, the local equilibrium time, and latitudinal differential heating. Most importantly, this intensity is strongly regulated in the coupled system, with a saturation level that can be reached at a modest coupling strength. The saturation west-east sea surface temperature difference (and the associated Walker circulation) corresponds to about one-quarter of the latitudinal differential equilibrium temperature. This regulation is caused primarily by the decoupling of the SST gradient from a strong ocean current. The author`s estimate suggests that the present Pacific is near the saturation state. Furthermore, the much weaker Walker circulation system in the Atlantic Ocean is interpreted as being the result of the influence of the adjacent land, which is able to extend into the entire Atlantic to change the zonal distribution of the trade wind. The theory is also applied to understand the tropical climatology in coupled GCM simulations, in the Last Glacial Maximum climate, and in the global warming climate, as well as in the regulation of the tropical sea surface temperature. 41 refs., 15 figs.

  9. Effect of immunisation with cancer procoagulant on the growth of Walker 256 carcinosarcoma cells in rats.

    PubMed

    Kamocka, M; Kaplinska, K; Mielicki, W P

    2006-10-01

    The effect of preimmunisation with cancer procoagulant (CP) on the growth of Walker 256 carcinosarcoma cells in Wistar Lew/Han/IMP rats in vivo has been analysed. One group of rats was immunised with CP purified from human amnion-chorion membranes. The rest of the animals (control groups) were injected with 0.9% NaCl in Freund's adjuvant or were not immunised at all. When the presence of polyclonal anti-CP antibody was detected in CP-immunised rats' serum, all (CP-immunised and control) animals were injected i.p. with 4.8 x 10(5) Walker 256 cells per rat. After 5 days ascitic fluid was collected and viable cells were counted. The complete lack of viable Walker 256 carcinosarcoma cells in 24% of the CP-immunised rats was observed. However, the viable neoplastic cells were present in all control (NaCl-injected and nonimmunised) animals. It seems possible that CP plays an important role in tumour progression, so immunisation with CP can reduce the risk of development of malignant disease.

  10. Test pilots 1962 - Thompson, McKay, Dana, Armstrong, Peterson, Butchart, Walker

    NASA Technical Reports Server (NTRS)

    1962-01-01

    A group photo of NASA research pilots at the front door of the Flight Research Center headquarters building. In the front row are (left to right) Milt Thompson, Jack McKay, and Bill Dana. All three flew the X-15, and Thompson and Dana were also involved in the lifting body flights. McKay was injured in a crash landing in X-15 #2. Although he recovered, the injuries eventually forced him to retire from research flying. In the back row (left to right) are Neil Armstrong, Bruce Peterson, Stanley Butchart, and Joe Walker. Armstrong and Walker also both flew the X-15. Soon after this photo was taken, Armstrong was selected as an astronaut, and seven years later became the first man to walk on the Moon. Walker made the highest flight in the X-15, reaching 354,200 feet. He then went on to fly the Lunar Landing Research Vehicle, and was killed on June 8, 1966 when his F-104N collided with the XB-70. Peterson made the first flight in the HL-10 lifting body, and was later badly injured in the crash of the M2-F2 lifting body. Butchart flew a wide range of research missions in the 1950s, and was the B-29 drop plane pilot for a number of rocket flight.

  11. Neurovascular Coupling is Impaired in Slow Walkers: The MOBILIZE Boston Study

    PubMed Central

    Sorond, Farzaneh A.; Kiely, Dan K.; Galica, Andrew; Moscufo, Nicola; Serrador, Jorge M.; Iloputaife, Ike; Egorova, Svetlana; Dell'Oglio, Elisa; Meier, Dominik; Newton, Elizabeth; Milberg, William P.; Guttmann, Charles; Lipsitz, Lewis A.

    2011-01-01

    Objective Neurovascular coupling may be involved in compensatory mechanisms responsible for preservation of gait speed in elderly people with cerebrovascular disease. Our study examines the association between neurovascular coupling in the middle cerebral artery and gait speed in elderly individuals with impaired cerebral vasoreactivity. Methods Twenty-two fast and 20 slow walkers in the lowest quartile of cerebral vasoreactivity were recruited from the MOBILIZE Boston Study. Neurovascular coupling was assessed in bilateral middle cerebral arteries by measuring cerebral blood flow during the N-Back Task. Cerebral white matter hyperintensities were measured for each group using magnetic resonance imaging. Results Neurovascular coupling was attenuated in slow compared to fast walkers (2.8% [CI95%: −0.9–6.6] vs. 8.2% [CI95%: 4.7–11.8]; p=0.02). The odds of being a slow walker were 6.4 (CI95%: 1.7–24.9, p=0.007) if there was a high burden of white matter hyperintensity, however, this risk increased to 14.5 (CI95%: 2.3–91.1, p=0.004) if neurovascular coupling was also attenuated. Interpretation Our results suggest that intact neurovascular coupling may help preserve mobility in elderly people with cerebral microvascular disease. PMID:21674588

  12. The influence of ENSO on the equatorial Atlantic precipitation through the Walker circulation in a CGCM

    NASA Astrophysics Data System (ADS)

    Sasaki, Wataru; Doi, Takeshi; Richards, Kelvin J.; Masumoto, Yukio

    2015-01-01

    The link between El Niño/Southern Oscillation (ENSO) and the equatorial Atlantic precipitation during boreal spring (March-April-May) is explored using a coupled general circulation model (CGCM). Interannual variability of the equatorial Atlantic sea surface temperature (SST) in the CGCM is excluded by nudging the modeled SST toward the climatological monthly mean of observed SST in the equatorial Atlantic, but full air-sea coupling is allowed elsewhere. It is found that the equatorial Atlantic precipitation is reduced (increased) during El Niño (La Niña) in the case where the interannual variability of the equatorial Atlantic SST is disabled. The precipitation anomalies in the equatorial Atlantic during ENSO are not strongly associated with the meridional migration of the Atlantic inter-tropical convergence zone. We find the reduced precipitation in the equatorial Atlantic during El Niño is associated with an enhanced Atlantic Walker circulation characterized by strengthened low-level easterlies and anomalous dry, downward winds over the equatorial Atlantic, while the Pacific Walker circulation is weakened. The upper-level anomalous westerlies over the equatorial Atlantic are consistent with a Matsuno-Gill-type response to heating in the eastern equatorial Pacific. Our results of the CGCM experiments suggest that changes to the Walker circulation induced by ENSO contribute significantly to changes in precipitation over the equatorial Atlantic.

  13. In the footsteps of biological motion and multisensory perception: judgments of audiovisual temporal relations are enhanced for upright walkers.

    PubMed

    Saygin, Ayse Pinar; Driver, Jon; de Sa, Virginia R

    2008-05-01

    Observers judged whether a periodically moving visual display (point-light walker) had the same temporal frequency as a series of auditory beeps that in some cases coincided with the apparent footsteps of the walker. Performance in this multisensory judgment was consistently better for upright point-light walkers than for inverted point-light walkers or scrambled control stimuli, even though the temporal information was the same in the three types of stimuli. The advantage with upright walkers disappeared when the visual "footsteps" were not phase-locked with the auditory events (and instead offset by 50% of the gait cycle). This finding indicates there was some specificity to the naturally experienced multisensory relation, and that temporal perception was not simply better for upright walkers per se. These experiments indicate that the gestalt of visual stimuli can substantially affect multisensory judgments, even in the context of a temporal task (for which audition is often considered dominant). This effect appears to be constrained by the ecological validity of the particular pairings. PMID:18466408

  14. Upper-Ocean Heat Balance Processes and the Walker Circulation in CMIP5 Model Projections

    NASA Technical Reports Server (NTRS)

    Robertson, F. R.; Roberts, J. B.; Funk, C.; Lyon, B.; Ricciardulli, L.

    2012-01-01

    Considerable uncertainty remains as to the importance of mechanisms governing decadal and longer variability of the Walker Circulation, its connection to the tropical climate system, and prospects for tropical climate change in the face of anthropogenic forcing. Most contemporary climate models suggest that in response to elevated CO2 and a warmer but more stratified atmosphere, the required upward mass flux in tropical convection will diminish along with the Walker component of the tropical mean circulation as well. Alternatively, there is also evidence to suggest that the shoaling and increased vertical stratification of the thermocline in the eastern Pacific will enable a muted SST increase there-- preserving or even enhancing some of the dynamical forcing for the Walker cell flow. Over the past decade there have been observational indications of an acceleration in near-surface easterlies, a strengthened Pacific zonal SST gradient, and globally-teleconnected dislocations in precipitation. But is this evidence in support of an ocean dynamical thermostat process posited to accompany anthropogenic forcing, or just residual decadal fluctuations associated with variations in warm and cold ENSO events and other stochastic forcing? From a modeling perspective we try to make headway on this question by examining zonal variations in surface energy fluxes and dynamics governing tropical upper ocean heat content evolution in the WCRP CMIP5 model projections. There is some diversity among model simulations; for example, the CCSM4 indicates net ocean warming over the IndoPacific region while the CSIRO model concentrates separate warming responses over the central Pacific and Indian Ocean regions. The models, as with observations, demonstrate strong local coupling between variations in column water vapor, downward surface longwave radiation and SST; but the spatial patterns of changes in the sign of this relationship differ among models and, for models as a whole, with

  15. Effect of botulinum toxin type A on gait of children who are idiopathic toe-walkers.

    PubMed

    Brunt, Denis; Woo, Raymund; Kim, Hyeong Dong; Ko, Man Soo; Senesac, Claudia; Li, Shuman

    2004-01-01

    The purpose of this study was to determine the effects of botulinum toxin type A treatment on ankle muscle activity during gait of children who are idiopathic toe-walkers. Five children who were idiopathic toe-walkers with a mean age was 4.34 years participated. Gait of the subjects was evaluated prior to, 20 days following, and 12 months following bilateral botulinum toxin type A injection of the gastrocnemius and soleus muscles. Subjects received physical therapy following the 20-day evaluation. Dependent variables were type of foot contact pattern and duration of swing-phase tibialis anterior activity and onset of stance-phase gastrocnemius relative to ground contact. Prior to treatment 51% of foot contacts were with the toe (heel just off the ground) or were digitigrade, while the remaining contacts were flat foot or heel strike. At approximately 20 days following treatment, only 8% of foot contacts were toe contact or digitigrade. Prior to treatment, mean gastrocnemius onset was 30 ms prior to foot contact and the duration of swing-phase tibialis anterior was only 345 ms. Following treatment (and a more normal foot contact pattern), mean gastrocnemius onset followed ground contact by 36 ms and tibialis anterior duration increased through terminal swing and into the loading response. The posttreatment improvement was maintained at 12-month follow-up. It appears that botulinum toxin type A treatment normalizes the ankle EMG pattern during gait and a more normal foot-strike pattern is obtained. These data are discussed in terms of a neuromotor rationale for the rehabilitation of children who are idiopathic toe-walkers to maintain posttreatment improvements.

  16. Optimal search strategies of space-time coupled random walkers with finite lifetimes.

    PubMed

    Campos, D; Abad, E; Méndez, V; Yuste, S B; Lindenberg, K

    2015-05-01

    We present a simple paradigm for detection of an immobile target by a space-time coupled random walker with a finite lifetime. The motion of the walker is characterized by linear displacements at a fixed speed and exponentially distributed duration, interrupted by random changes in the direction of motion and resumption of motion in the new direction with the same speed. We call these walkers "mortal creepers." A mortal creeper may die at any time during its motion according to an exponential decay law characterized by a finite mean death rate ω(m). While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ω(m)-dependent optimal frequency ω=ω(opt) that maximizes the probability of eventual target detection. We work primarily in one-dimensional (d=1) domains and examine the role of initial conditions and of finite domain sizes. Numerical results in d=2 domains confirm the existence of an optimal frequency of change of direction, thereby suggesting that the observed effects are robust to changes in dimensionality. In the d=1 case, explicit expressions for the probability of target detection in the long time limit are given. In the case of an infinite domain, we compute the detection probability for arbitrary times and study its early- and late-time behavior. We further consider the survival probability of the target in the presence of many independent creepers beginning their motion at the same location and at the same time. We also consider a version of the standard "target problem" in which many creepers start at random locations at the same time. PMID:26066127

  17. Optimal search strategies of space-time coupled random walkers with finite lifetimes.

    PubMed

    Campos, D; Abad, E; Méndez, V; Yuste, S B; Lindenberg, K

    2015-05-01

    We present a simple paradigm for detection of an immobile target by a space-time coupled random walker with a finite lifetime. The motion of the walker is characterized by linear displacements at a fixed speed and exponentially distributed duration, interrupted by random changes in the direction of motion and resumption of motion in the new direction with the same speed. We call these walkers "mortal creepers." A mortal creeper may die at any time during its motion according to an exponential decay law characterized by a finite mean death rate ω(m). While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ω(m)-dependent optimal frequency ω=ω(opt) that maximizes the probability of eventual target detection. We work primarily in one-dimensional (d=1) domains and examine the role of initial conditions and of finite domain sizes. Numerical results in d=2 domains confirm the existence of an optimal frequency of change of direction, thereby suggesting that the observed effects are robust to changes in dimensionality. In the d=1 case, explicit expressions for the probability of target detection in the long time limit are given. In the case of an infinite domain, we compute the detection probability for arbitrary times and study its early- and late-time behavior. We further consider the survival probability of the target in the presence of many independent creepers beginning their motion at the same location and at the same time. We also consider a version of the standard "target problem" in which many creepers start at random locations at the same time.

  18. Phosphorus and soil development: does the Walker and Syers model apply to semiarid ecosystems?

    PubMed

    Selmants, Paul C; Hart, Stephen C

    2010-02-01

    The Walker and Syers model of phosphorus (P) transformations during pedogenesis is widely accepted for the development of humid ecosystems, but long-term P dynamics of more arid ecosystems remain poorly understood. We tested the Walker and Syers model in semiarid piñon-juniper woodlands by measuring soil P fractions under tree canopies and in intercanopy spaces along a well-constrained, approximately 3000 ka (1 ka = 1000 years) volcanic substrate age gradient in northern Arizona, USA. The various pools of soil P behaved largely as predicted; total soil P and primary mineral P declined consistently with substrate age, labile inorganic P increased early in soil development and then declined at later stages, and organic phosphorus increased consistently across the chronosequence. Within each site, soils under tree canopies tended to have higher concentrations of labile and intermediately available P fractions compared to intercanopy soils. However, the degree of spatial heterogeneity conferred by tree islands was moderated by the stage of soil development. In contrast, tree islands had no influence on within-site distribution of more recalcitrant soil P pools, which appear to be controlled solely by the stage of pedogenesis. Coincident with declines in total P, primary mineral P, and labile inorganic P, we found that phosphatase enzyme activity increased with substrate age; a result consistent with greater ecosystem-level P demand on older, more highly weathered substrates. Our results suggest that, compared to humid climates, reduced inputs of water, energy, and acidity to semiarid ecosystems slow the rate of change in P fractions during pedogenesis, but the overall pattern remains consistent with the Walker and Syers model. Furthermore, our data imply that pedogenic change may be an important factor controlling the spatial distribution of labile P pools in semiarid ecosystems. Taken together, these data should both broaden and unify terrestrial ecosystem

  19. An appraisal of the water resources of the Walker River Indian Reservation, Nevada

    USGS Publications Warehouse

    Schaefer, Donald H.

    1980-01-01

    Increasing interest in expanding the livestock and agricultural operations on the Walker River Indian Reservation, Nev., has prompted the Walker River Paiute Tribe to have the present and available water resources of the reservation appraised and proposed sites for new wells evaluated. Flow of the Walker River into the reservation averages about 113,000 acre-feet a year. Of this amount, about 42,000 acre-feet is used on the reservation, recharging the gound-water system and supplying irrigation water for alfalfa and pasture crops. The water quality of the river water is well suited for these purposes, and the possibility of expanding surface-water use exists. A mathematical model of the ground-water system was constructed to test various assumptions about recharge and discharge rates. The model generated water-level contours that agreed reasonably well with measured water levels, median deviation was 12 feet. With additional data , the model could be used in the future to test the feasibility of evapotranspiration salvage at the seven proposed sites for new stock and irrigation wells. The primary users of ground water on the reservation are phreatophytes and playa surfaces. They allow ground water to be lost to evaporation. About 19,000 acre-feet per year is lost through this mechanism. Domestic and livestock uses account for only about 250 acre-feet per year. Total recharge to the ground-water system amounts to about 30 ,000 acre-feet per year, and the possibility of more extensive use of ground water on the reservation exists. Quality of the ground water in most areas is suitable for all intended purposes. (USGS)

  20. Electric-field-controlled suppression of Walker breakdown and chirality switching in magnetic domain wall motion

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Bo; Li, You-Quan

    2016-07-01

    We theoretically study the dynamics of a magnetic domain wall controlled by an electric field in the presence of the spin flexoelectric interaction. We reveal that this interaction generates an effective spin torque and results in significant changes in the current-driven domain wall motion. In particular, the electric field can stabilize the domain wall motion, leading to strong suppression of the current-induced Walker breakdown and thus allowing a higher maximum wall velocity. We can furthermore use this electric-field control to efficiently switch the chirality of a moving domain wall in the steady regime.

  1. Brain catecholamine alterations accompanying development of anorexia in rats bearing the Walker 256 carcinoma.

    PubMed

    Nichols, M B; Maickel, R P; Yim, G K

    1985-06-10

    In the present study, the relationship between central catecholamine levels and the anorexia induced by Walker 256 carcinoma was investigated. Results indicate that the anorexia is not due to depletion of central catecholamines. Tumor bearing rats sacrificed at night, when spontaneous food intake is selectively depressed, showed increased norepinephrine levels in the hypothalamus, cortex and hippocampus and increased dopamine levels in the striatum, midbrain, and cortex. Increased nighttime hypothalamic norepinephrine levels were positively correlated with the magnitude of spontaneous food intake in tumor rats.

  2. Local inhomogeneities in a Robertson-Walker background. I. General framework

    SciTech Connect

    Lake, K.

    1980-09-15

    A complete generalization of the ''Swiss cheese'' type of locally inhomogeneous cosmologies is given. Neither the explicity form of the spherically symmetric interior metric nor the spatial curvature and equation of state of the Robertson-Walker background is restricted a priori. The history, mass, and mass growth rate of any timelike inhomogeneity is developed in terms of a single function characteristic of the inhomogeneity. Recent results which have generalized the standard ''Swiss cheese'' case of a Vaidra interior metric follow immediately from the framework given here.

  3. Unitary vector fields are Fermi-Walker transported along Rytov-Legendre curves

    NASA Astrophysics Data System (ADS)

    Crasmareanu, Mircea; Frigioiu, Camelia

    2015-07-01

    Fix ξ a unitary vector field on a Riemannian manifold M and γ a non-geodesic Frenet curve on M satisfying the Rytov law of polarization optics. We prove in these conditions that γ is a Legendre curve for ξ if and only if the γ-Fermi-Walker covariant derivative of ξ vanishes. The cases when γ is circle or helix as well as ξ is (conformal) Killing vector filed or potential vector field of a Ricci soliton are analyzed and an example involving a three-dimensional warped metric is provided. We discuss also K-(para)contact, particularly (para)Sasakian, manifolds and hypersurfaces in complex space forms.

  4. Seasonal population patterns of Spalangia endius Walker (Hymenoptera: Chalcidoidea) at a refuse dumping ground in Malaysia.

    PubMed

    Sulaiman, S; Omar, B; Omar, S; Jeffery, J; Ghauth, I; Busparani, V

    1991-11-01

    A study on population patterns of the parasitoid Spalangia endius Walker at a dumping ground near Kuala Lumpur city showed that the percentage of S. endius adult emergence varied seasonally. During the relatively heavy rainfall months of August and November 1988, and January, March, and April 1989, the population of S. endius adult emergence were low (0-14.2%) compared to the less rainy months of July, September, and December 1988, and May 1989 (29.3-39.6%). This information could be useful in formulating strategies to reduce house fly population at the refuse dumping ground through integrated pest management programs.

  5. Motility of Colonial Choanoflagellates and the Statistics of Aggregate Random Walkers.

    PubMed

    Kirkegaard, Julius B; Marron, Alan O; Goldstein, Raymond E

    2016-01-22

    We illuminate the nature of the three-dimensional random walks of microorganisms composed of individual organisms adhered together. Such aggregate random walkers are typified by choanoflagellates, eukaryotes that are the closest living relatives of animals. In the colony-forming species Salpingoeca rosetta we show that the beating of each flagellum is stochastic and uncorrelated with others, and the vectorial sum of the flagellar propulsion manifests as stochastic helical swimming. A quantitative theory for these results is presented and species variability discussed. PMID:26849616

  6. Central Diabetes Insipidus, Central Hypothyroidism, Renal Tubular Acidosis and Dandy-Walker Syndrome: New Associations

    PubMed Central

    Alafif, MM; Aljaid, SS; Al-Agha, AE

    2015-01-01

    Dandy-Walker syndrome (DWS) is a rare brain malformation involving the cerebellum, and the fluid filled spaces around it, usually detected during the antenatal period or the early infancy. Clinically, it is characterized by mental retardation, developmental delay as well as cerebellar ataxia. It has been frequently associated with other conditions such as congenital heart diseases, primary hypothyroidism, and other disorders of the central nervous, gastrointestinal, genitourinary, and orthopedic systems. In this report, we describe a 3-month-old Saudi boy with the rare association of DWS with central diabetes insipidus, congenital central hypothyroidism, and type-2 renal tubular acidosis. PMID:25861538

  7. Very severe spinal muscular atrophy: Type 0 with Dandy-Walker variant

    PubMed Central

    Gathwala, Geeta; Silayach, Joginder; Bhakhari, Bhanu Kiran; Narwal, Varun

    2014-01-01

    Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by degeneration of alpha motor neurons in the spinal cord, resulting in progressive proximal muscle weakness and paralysis. In addition to the three classical SMA types, a new form known as type 0 with intrauterine onset, profound hypotonia and a progressive and early fatal course has been described. Herein we report a case of type 0 SMA with a Dandy Walker variant anomaly, which has not hitherto been reported in the world literature. PMID:24891907

  8. Very severe spinal muscular atrophy: Type 0 with Dandy-Walker variant.

    PubMed

    Gathwala, Geeta; Silayach, Joginder; Bhakhari, Bhanu Kiran; Narwal, Varun

    2014-01-01

    Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease characterized by degeneration of alpha motor neurons in the spinal cord, resulting in progressive proximal muscle weakness and paralysis. In addition to the three classical SMA types, a new form known as type 0 with intrauterine onset, profound hypotonia and a progressive and early fatal course has been described. Herein we report a case of type 0 SMA with a Dandy Walker variant anomaly, which has not hitherto been reported in the world literature. PMID:24891907

  9. Corrections to Hawking-like radiation for a Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Zhu, Tao; Ren, Ji-Rong

    2009-07-01

    Recently, a Hamilton-Jacobi method beyond the semiclassical approximation in black hole physics was developed by Banerjee and Majhi. We generalize their analysis of black holes to the case of a Friedmann-Robertson-Walker (FRW) universe. It is shown that all the higher order quantum corrections in the single particle action are proportional to the usual semiclassical contribution. The corrections to the Hawking-like temperature and entropy of the apparent horizon for the FRW universe are also obtained. In the corrected entropy, the area law involves a logarithmic area correction together with the standard term with the inverse power of the area.

  10. Synthesis of benzoxazole derivatives of honokiol as insecticidal agents against Mythimna separata Walker.

    PubMed

    Yang, Chun; Zhi, Xiaoyan; Xu, Hui

    2015-01-01

    A series of novel benzoxazole compounds derived from a naturally occurring neolignan honokiol were prepared. Their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker) in vivo. Most of the tested derivatives exhibited more potential insecticidal activity than their precursor honokiol at the concentration of 1mg/mL. Especially compound 6e, containing 4-acetyloxyphenyl groups at the C8 and C8' positions, displayed the most potent insecticidal activity with the final mortality rate of 62.1%.

  11. Changes in Central Walker Lane Strain Accommodation near Bridgeport, California; as told by the Stanislaus Group

    NASA Astrophysics Data System (ADS)

    Carlson, C. W.; Pluhar, C. J.; Glen, J. M.; Farner, M. J.

    2012-12-01

    Accommodating ~20-25% of the dextral-motion between the Pacific and North American plates the Walker Lane is represented as an elongate, NW oriented, region of active tectonics positioned between the northwesterly-translating Sierra Nevada microplate and the east-west extension of the Basin and Range. This region of transtension is being variably accommodated on regional-scale systems of predominantly strike-slip faulting. At the western edge of the central Walker Lane (ca. 38°-39°N latitude) is a region of crustal-scale blocks bounded by wedge-shaped depositional-basins and normal-fault systems, here defined as the west-central Walker Lane (WCWL). Devoid of obvious strike-slip faulting, the presence of tectonic-block vertical-axis rotations in the WCWL represents unrecognized components of dextral-shearing and/or changes of strain-accommodation over time. We use paleomagnetic reference directions for Eureka Valley Tuff (EVT) members of the late Miocene Stanislaus Group as spatial and temporal markers for documentation of tectonic-block vertical-axis rotations near Bridgeport, CA. Study-site rotations revealed discrete rotational domains of mean vertical-axis rotation ranging from ~10°-30° with heterogeneous regional distribution. Additionally, the highest measured magnitudes of vertical-axis rotation (~50°-60° CW) define a 'Region of High Strain' that includes the wedge-shaped Bridgeport Valley (Basin). This study revealed previously-unrecognized tectonic rotation of reference direction sites from prior studies for two (By-Day and Upper) of the three members of the EVT, resulting in under-estimates of regional strain accommodation by these studies. Mean remanent directions and virtual geomagnetic poles utilized in our study yielded a recalculated reference direction for the By-Day member of: Dec.=353.2°; Inc.= 43.7°; α95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously

  12. The influence of ocean surface temperature gradient and continentality on the Walker circulation. I - Prescribed tropical changes

    NASA Technical Reports Server (NTRS)

    Chervin, R. M.; Druyan, L. M.

    1984-01-01

    A coarse mesh global climate model has been developed to assess ocean surface temperature (OST) gradient and continentality influences on the Walker circulation, which is characterized in the zonal plane by three pairs of clockwise and counterclockwise cells in the troposphere. The model response exhibits statistically significant changes in the intensity of the various cells and branches with small shifts in the east-west extent. The overall structure in the zonal plane for experiments with the coldest and with mean temperatures, however, remained unchanged. In an experiment involving the replacement of the South American continent by an ocean with OSTs linearly interpolated from the eastern Pacific to the western Atlantic, a dramatic change took place in the structure of the Walker circulation. It is concluded that both continentality and OST gradient are important Walker circulation forcing mechanisms.

  13. Treatment of rat Walker-256 carcinosarcoma with photodynamic therapy and endotoxin irradiated with high-energy electrons

    NASA Astrophysics Data System (ADS)

    Dima, Vasile F.; Vasiliu, Virgil V.; Laky, Dezideriu; Ionescu, Mircea D.; Dima, Stefan V.

    1994-03-01

    Experiments were performed on five batches of Wistar inbred rats with Walker-256 carcinosarcoma receiving sole treatment photodynamic therapy (PDT), irradiated endotoxin (R-LPS), native-endotoxin (N-LPS), or associated therapy (PDT + R-LPS) and the control batch (saline) consisted of animals with untreated Walker-256 tumors. The results were as follows: the sole treatment (PDT, R-LPS, N-LPS) gave survival rates between 56.3 and 60.7% and cure rates ranging from 32.1 to 37.5%. The `combined' therapy in multiple doses increased significantly (88.6%) the survival rate of tumor bearing rats as well as the highest incidence of complete tumor regression (71.4%). This work demonstrates that `combined' photodynamic and immunotherapy with irradiated endotoxin stimulates cell-mediated antitumoral activity and induces changes in the tumoral incidence in Walker-256 carcinosarcoma in the rat model.

  14. Baseline-dependent effect of noise-enhanced insoles on gait variability in healthy elderly walkers.

    PubMed

    Stephen, Damian G; Wilcox, Bethany J; Niemi, James B; Franz, Jason R; Franz, Jason; Kerrigan, Dr; Kerrigan, D Casey; D'Andrea, Susan E

    2012-07-01

    The purpose of this study was to determine whether providing subsensory stochastic-resonance mechanical vibration to the foot soles of elderly walkers could decrease gait variability. In a randomized double-blind controlled trial, 29 subjects engaged in treadmill walking while wearing sandals customized with three actuators capable of producing stochastic-resonance mechanical vibration embedded in each sole. For each subject, we determined a subsensory level of vibration stimulation. After a 5-min acclimation period of walking with the footwear, subjects were asked to walk on the treadmill for six trials, each 30s long. Trials were pair-wise random: in three trials, actuators provided subsensory vibration; in the other trials, they did not. Subjects wore reflective markers to track body motion. Stochastic-resonance mechanical stimulation exhibited baseline-dependent effects on spatial stride-to-stride variability in gait, slightly increasing variability in subjects with least baseline variability and providing greater reductions in variability for subjects with greater baseline variability (p<.001). Thus, applying stochastic-resonance mechanical vibrations on the plantar surface of the foot reduces gait variability for subjects with more variable gait. Stochastic-resonance mechanical vibrations may provide an effective intervention for preventing falls in healthy elderly walkers.

  15. Changes in Soil Carbon and Nitrogen in Forests of Walker Branch Watershed 1972-2004

    SciTech Connect

    Todd Jr, Donald E; Johnson, Dale W.; Trettin, Carl

    2007-01-01

    Changes in soil C and N concentrations and contents in four samplings during a 32-yr period on Walker Branch watershed in Tennessee were determined and compared with previously measured C and N fluxes and with changes in ecosystem C and N pools during this period. Soils showed significant increases in C and N concentrations in surface horizons from 1972 to 2004, and most of this increase occurred between 1972 and 1982. A previously observed decline in soil C and N contents between 1982 and 1993 was reversed in 2004 such that the latter increased to near 1982 values. The changes in soil C content could be approximately accounted for by previously measured litterfall and soil CO{sub 2}-C fluxes. Changes in soil N could not be accounted for by leaching, increments in vegetation, or by laboratory bias, changes during sample storage, or reasonable estimates of field sampling errors. We conclude that, although vegetation C and N pools increased steadily during the sampling period in most cases, changes in soil C and N pools on Walker Branch watershed are highly variable in both space and time, and there has been no unidirectional trend during the time period of this study.

  16. Walker 256 Tumor Growth Suppression by Crotoxin Involves Formyl Peptide Receptors and Lipoxin A4

    PubMed Central

    Brigatte, Patrícia; Faiad, Odair Jorge; Ferreira Nocelli, Roberta Cornélio; Landgraf, Richardt G.; Palma, Mario Sergio; Cury, Yara; Curi, Rui; Sampaio, Sandra Coccuzzo

    2016-01-01

    We investigated the effects of Crotoxin (CTX), the main toxin of South American rattlesnake (Crotalus durissus terrificus) venom, on Walker 256 tumor growth, the pain symptoms associated (hyperalgesia and allodynia), and participation of endogenous lipoxin A4. Treatment with CTX (s.c.), daily, for 5 days reduced tumor growth at the 5th day after injection of Walker 256 carcinoma cells into the plantar surface of adult rat hind paw. This observation was associated with inhibition of new blood vessel formation and decrease in blood vessel diameter. The treatment with CTX raised plasma concentrations of lipoxin A4 and its natural analogue 15-epi-LXA4, an effect mediated by formyl peptide receptors (FPRs). In fact, the treatment with Boc-2, an inhibitor of FPRs, abolished the increase in plasma levels of these mediators triggered by CTX. The blockage of these receptors also abolished the inhibitory action of CTX on tumor growth and blood vessel formation and the decrease in blood vessel diameter. Together, the results herein presented demonstrate that CTX increases plasma concentrations of lipoxin A4 and 15-epi-LXA4, which might inhibit both tumor growth and formation of new vessels via FPRs. PMID:27190493

  17. Neimark-Sacker bifurcations and evidence of chaos in a discrete dynamical model of walkers

    NASA Astrophysics Data System (ADS)

    Rahman, Aminur; Blackmore, Denis

    2016-10-01

    Bouncing droplets on a vibrating fluid bath can exhibit wave-particle behavior, such as being propelled by interacting with its own wave field. These droplets seem to walk across the bath, and thus are dubbed walkers. Experiments have shown that walkers can exhibit exotic dynamical behavior indicative of chaos. While the integro-differential models developed for these systems agree well with the experiments, they are difficult to analyze mathematically. In recent years, simpler discrete dynamical models have been derived and studied numerically. The numerical simulations of these models show evidence of exotic dynamics such as period doubling bifurcations, Neimark--Sacker (N--S) bifurcations, and even chaos. For example, in [Gilet, PRE 2014], based on simulations Gilet conjectured the existence of a supercritical N-S bifurcation as the damping factor in his one-dimensional path model. We prove Gilet's conjecture and more; in fact, both supercritical and subcritical (N-S) bifurcations are produced by separately varying the damping factor and wave-particle coupling for all eigenmode shapes. Then we compare our theoretical results with some previous and new numerical simulations, and find complete qualitative agreement. Furthermore, evidence of chaos is shown by numerically studying a global bifurcation.

  18. Investigating GAIM-GM's Capability to Sense Ionospheric Irregularities via Walker Satellite Constellations

    NASA Astrophysics Data System (ADS)

    McClung, B.

    2015-12-01

    GAIM-GM is a modularized physics based data assimilation model, that ingests data from multiple data sources. One data source is slant total electron content (TEC) from a ground station network to satellites, and along the occultation path between multiple satellites. This study examines GAIM-GM's capability to sense a scintillation feature in the ionosphere, overlaid on an IFM electron density grid, from simulated satellite constellations ingesting the slant TEC values into GAIM-GM. Satellite constellations were developed in an extension of Matlab, called STK. A real ground station network generated from IGS was ingested into STK to calculate access times to the satellite constellation and use the access data to compute the slant TEC values on the perturbed IFM grid. It was discovered that a Walker constellation would give the most frequent revisit time to the scintillation feature, which co-rotates with the Earth, capturing both the day and nightside ionosphere throughout the evaluation period (96 hrs). The size of the feature was varied along with the number of satellites in the Walker constellation. 25 different scenarios with these parameters varied were created to determine the sensitivity of GAIM-GM to sense the feature. A simple heuristic algorithm was applied comparing the truth data, in this case the perturbed IFM grid, to the GAIM-GM output in each scenario across the entire grid, and for those grid points within the feature.

  19. Distribution of the time at which N vicious walkers reach their maximal height

    NASA Astrophysics Data System (ADS)

    Rambeau, Joachim; Schehr, Grégory

    2011-06-01

    We study the extreme statistics of N nonintersecting Brownian motions (vicious walkers) over a unit time interval in one dimension. Using path-integral techniques we compute exactly the joint distribution of the maximum M and of the time τM at which this maximum is reached. We focus in particular on nonintersecting Brownian bridges (“watermelons without wall”) and nonintersecting Brownian excursions (“watermelons with a wall”). We discuss in detail the relationships between such vicious walkers models in watermelon configurations and stochastic growth models in curved geometry on the one hand and the directed polymer in a disordered medium (DPRM) with one free end point on the other hand. We also check our results using numerical simulations of Dyson’s Brownian motion and confront them with numerical simulations of the polynuclear growth model (PNG) and of a model of DPRM on a discrete lattice. Some of the results presented here were announced in a recent letter [J. Rambeau and G. Schehr, Europhys. Lett.EULEEJ0295-507510.1209/0295-5075/91/60006 91, 60006 (2010)].

  20. A biological walker is faster and better recognized when aligned with body axis observer.

    PubMed

    Barbieri, Guillaume; Fouque, Florent; Pozzo, Thierry; Pérennou, Dominic

    2013-09-01

    The representation of the vertical direction is a compromise between the directions given by the egocentric and allocentric references. Dissociations between these two referentials in the discrimination of a biological walker which typically refers to a model of verticality questions the coordinate system (allocentric and/or egocentric) used to perceive it. With a point-light display paradigm, the characteristics of an artificial walking pattern were manipulated in order to offer to 10 healthy participants (5 men/5 women; 24.6±3.4 years) a female or male locomotion which had to be identified as such. The body position of the viewer (sitting/lying) and the walking pattern viewed (aligned/rotated in relation to the egocentric referential) were crossed. Three indices were analyzed and 200 trials recorded: percentage of correct identification, reaction time and confidence score. This paper confirms the validity of the walking pattern model since the more pronounced the gradient of the walking pattern (as female or male) the better the recognition. Furthermore, whatever the body position, artificial walking patterns were more easily identified when they were aligned with the egocentric referential rather than tilted. The participant gender had no influence on the walking pattern recognition. We conclude that the perception of a biological walker referenced to the vertical is exclusively improved by a representation of the spatial information in an egocentric coordinate system. PMID:23768527

  1. New perspectives on quaternary faulting in the southern Walker Lane, Nevada and California

    SciTech Connect

    Reheis, M.C.; Noller, J.S.

    1987-12-31

    A preliminary survey of aerial photographs of the southern Walker Lane began in late 1986. The purpose of this survey is to determine the nature and scope of future studies required to ascertain whether the apparent concentration of Quaternary faults in and near the Nevada Test Site is real or is simply a result of the greater effort invested in mapping Quaternary deposits in that area, and determine whether faults in the southern Walker Lane are active and could produce significant earthquakes. The survey is focused on the area extending south from Lone Mountain to Pahrump Valley and east from the Furnace Creek fault zone to an irregular line passing through the Cactus Range and Pahute Mesa. Lineaments and scraps were identified on stereopairs of black-and-white aerial photographs at scales of 1:80,000 or 1:60,000. The lineaments and and scarps were plotted on 1:24,000- and 1:62,500-scale topographic maps using a PG-2 plotter, and were color-coded according to distinctness and occurrence in Quaternary or Tertiary deposits (age assignments based on appearance in aerial photographs and on existing geologic maps). Additional lineaments identified on the topographic maps were also plotted. Areas of particular interest were selected for more detailed study using larger-scale aerial photographs. Most of the lineaments and scraps identified in the survey, although referred to as faults in this paper, have not been checked in the field. 11 refs., 1 fig.

  2. Reaction diffusion dynamics and the Schryer-Walker solution for domain walls of the Landau-Lifshitz-Gilbert equation

    NASA Astrophysics Data System (ADS)

    Benguria, R. D.; Depassier, M. C.

    2016-04-01

    We study the dynamics of the equation obtained by Schryer and Walker for the motion of domain walls. The reduced equation is a reaction diffusion equation for the angle between the applied field and the magnetization vector. If the hard-axis anisotropy Kd is much larger than the easy-axis anisotropy Ku, there is a range of applied fields where the dynamics does not select the Schryer-Walker solution. We give an analytic expression for the speed of the domain wall in this regime and the conditions for its existence.

  3. Pore size distribution and methane equilibrium conditions at Walker Ridge Block 313, northern Gulf of Mexico

    SciTech Connect

    Bihani, Abhishek; Daigle, Hugh; Cook, Ann; Glosser, Deborah; Shushtarian, Arash

    2015-12-15

    Coexistence of three methane phases (liquid (L), gas (G), hydrate (H)) in marine gas hydrate systems may occur according to in-situ pressure, temperature, salinity and pore size. In sediments with salinity close to seawater, a discrete zone of three-phase (3P) equilibrium may occur near the base of the regional hydrate stability zone (RHSZ) due to capillary effects. The existence of a 3P zone influences the location of the bottom-simulating reflection (BSR) and has implications for methane fluxes at the base of the RHSZ. We studied hydrate stability conditions in two wells, WR313-G and WR313-H, at Walker Ridge Block 313 in the northern Gulf of Mexico. We determined pore size distributions (PSD) by constructing a synthetic nuclear magnetic resonance (NMR) relaxation time distribution. Correlations were obtained by non-linear regression on NMR, gamma ray, and bulk density logs from well KC-151 at Keathley Canyon. The correlations enabled construction of relaxation time distributions for WR313-G and WR313-H, which were used to predict PSD through comparison with mercury injection capillary pressure measurements. With the computed PSD, L+H and L+G methane solubility was determined from in-situ pressure and temperature. The intersection of the L+G and L+H curves for various pore sizes allowed calculation of the depth range of the 3P equilibrium zone. As in previous studies at Blake Ridge and Hydrate Ridge, the top of the 3P zone moves upwards with increasing water depth and overlies the bulk 3P equilibrium depth. In clays at Walker Ridge, the predicted thickness of the 3P zone is approximately 35 m, but in coarse sands it is only a few meters due to the difference in absolute pore sizes and the width of the PSD. The thick 3P zone in the clays may explain in part why the BSR is only observed in the sand layers at Walker Ridge, although other factors may influence the presence or absence of a BSR.

  4. Pore Size Distribution and Methane Equilibrium Conditions at Walker Ridge Block 313, Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Bihani, A. D.; Daigle, H.; Cook, A.; Glosser, D.; Shushtarian, A.

    2015-12-01

    Coexistence of three methane phases (liquid (L), gas (G), hydrate (H)) in marine gas hydrate systems may occur according to in-situ pressure, temperature, salinity and pore size. In sediments with salinity close to seawater, a discrete zone of three-phase (3P) equilibrium may occur near the base of the regional hydrate stability zone (RHSZ) due to capillary effects. The existence of a 3P zone influences the location of the bottom-simulating reflection (BSR) and has implications for methane fluxes at the base of the RHSZ. We studied hydrate stability conditions in two wells, WR313-G and WR313-H, at Walker Ridge Block 313 in the northern Gulf of Mexico. We determined pore size distributions (PSD) by constructing a synthetic nuclear magnetic resonance (NMR) relaxation time distribution. Correlations were obtained by non-linear regression on NMR, gamma ray, and bulk density logs from well KC-151 at Keathley Canyon. The correlations enabled construction of relaxation time distributions for WR313-G and WR313-H, which were used to predict PSD through comparison with mercury injection capillary pressure measurements. With the computed PSD, L+H and L+G methane solubility was determined from in-situ pressure and temperature. The intersection of the L+G and L+H curves for various pore sizes allowed calculation of the depth range of the 3P equilibrium zone. As in previous studies at Blake Ridge and Hydrate Ridge, the top of the 3P zone moves upwards with increasing water depth and overlies the bulk 3P equilibrium depth. In clays at Walker Ridge, the predicted thickness of the 3P zone is approximately 35 m, but in coarse sands it is only a few meters due to the difference in absolute pore sizes and the width of the PSD. The thick 3P zone in the clays may explain in part why the BSR is only observed in the sand layers at Walker Ridge, although other factors may influence the presence or absence of a BSR.

  5. Uniqueness of complete maximal hypersurfaces in spatially open (n+1)-dimensional Robertson-Walker spacetimes with flat fiber

    NASA Astrophysics Data System (ADS)

    Pelegrín, José A. S.; Romero, Alfonso; Rubio, Rafael M.

    2016-06-01

    In this paper, under natural geometric and physical assumptions we provide new uniqueness and non-existence results for complete maximal hypersurfaces in spatially open Robertson-Walker spacetimes whose fiber is flat. Moreover, our results are applied to relevant spacetimes as the steady state spacetime, Einstein-de Sitter spacetime and radiation models.

  6. Quantum features derived from the classical model of a bouncer-walker coupled to a zero-point field

    NASA Astrophysics Data System (ADS)

    Schwabl, H.; Mesa Pascasio, J.; Fussy, S.; Grössing, G.

    2012-05-01

    In our bouncer-walker model a quantum is a nonequilibrium steady-state maintained by a permanent throughput of energy. Specifically, we consider a "particle" as a bouncer whose oscillations are phase-locked with those of the energy-momentum reservoir of the zero-point field (ZPF), and we combine this with the random-walk model of the walker, again driven by the ZPF. Starting with this classical toy model of the bouncer-walker we were able to derive fundamental elements of quantum theory [1]. Here this toy model is revisited with special emphasis on the mechanism of emergence. Especially the derivation of the total energy hslashωo and the coupling to the ZPF are clarified. For this we make use of a sub-quantum equipartition theorem. It can further be shown that the couplings of both bouncer and walker to the ZPF are identical. Then we follow this path in accordance with Ref. [2], expanding the view from the particle in its rest frame to a particle in motion. The basic features of ballistic diffusion are derived, especially the diffusion constant D, thus providing a missing link between the different approaches of our previous works [1, 2].

  7. PACAP and its receptors in migraine pathophysiology: Commentary on Walker et al., Br J Pharmacol 171: 1521–1533

    PubMed Central

    Edvinsson, Lars

    2015-01-01

    Linked Article This article is a Commentary on Walker CS, Sundrum T and Hay DL (2014). PACAP receptor pharmacology and agonist bias: analysis in primary neurons and glia from the trigeminal ganglia and transfected cells. Br J Pharmacol 171: 1521–1553. doi: 10.1111/bph.12541 PMID:24826981

  8. Confirmation of the Old World species Phricanthes flexilineana (Walker) in the New World tropics (Lepidoptera: Tortricidae: Phricanthini)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Old World species Phricanthes flexilinena (Walker) is reported from Costa Rica and Panama for the first time, confirming a nearly century-old report that the species occurs in the New World (i.e., Guyana). Two new larval host plants are reported for the species in Costa Rica: Tetracera volubilis...

  9. Fostering Locomotor Behavior of Children with Developmental Disabilities: An Overview of Studies Using Treadmills and Walkers with Microswitches

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Didden, Robert; Manfredi, Francesco; Putignano, Pietro; Stasolla, Fabrizio; Basili, Gabriella

    2009-01-01

    This paper provides an overview of studies using programs with treadmills or walkers with microswitches and contingent stimulation to foster locomotor behavior of children with developmental disabilities. Twenty-six studies were identified in the period 2000-2008 (i.e., the period in which research in this area has actually taken shape).…

  10. Walker 256/B malignant breast cancer cells disrupt osteoclast cytomorphometry and activity in rats: modulation by α-tocopherol acetate.

    PubMed

    Badraoui, Riadh; Ben-Nasr, Hmed; Amamou, Selma; El-May, Michèle Véronique; Rebai, Tarek

    2014-03-01

    We examined the effects of vitamin E supplementation (VES) on osteoclast (OC) resorbing activity and cytomorphometry in Walker 256/B tumor osteolytic rats. Twenty-four aged male rats were randomized into 3 groups: 6 were sham operated; 9 were injected in the right hind limb with Walker 256/B cells (W256 group); and 9 were injected as above and supplemented with VE (45mg/kg BW) (W256VE group). Twenty days later, bone mass (BV/TV) and some microarchitectural parameters were assessed. Some histodynamic parameters, cellular and nuclear form factors (FFC and FFN), and nuclear-cytoplasmic ratio (N/C) of OC were measured for each group. W256 group exhibited osteolytic lesions in the operated femora. Walker 256/B induced trabecular perforation and decreased BV/TV associated with significant increases in OC numbering (N.Oc/B.Ar and Oc.N/B.Pm) and activity (ES/BS and Oc.S/BS). While FFN remain unchanged, the FFC and N/C ratio increased in the W256 group. W256VE showed less osteolytic lesions. Moreover, disruption of bone microarchitecture and OC activity in W256VE group decreased. VES reduced the malignant Walker 256/B-induced enhanced OC resorbing activity with cytoinhibition rate reaching 41%. The protective effect of VE may be due to its modulation of OC cytomorphometry and subsequently their activity.

  11. Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models

    USGS Publications Warehouse

    Allander, Kip K.; Niswonger, Richard G.; Jeton, Anne E.

    2014-01-01

    For the baseline scenario, it was assumed that streamflow conditions from 1981 to 2010 will be repeated in the future. Results indicate that Walker Lake level and volume continue to decline but at a slower rate as the surface area of th

  12. Design and Construction of a Simple 3D Straight-Legged Passive Walker with Flat Feet and Ankle Springs

    NASA Astrophysics Data System (ADS)

    Narukawa, Terumasa; Yokoyama, Kazuto; Takahashi, Masaki; Yoshida, Kazuo

    To date, most passive walkers have been designed with arc-shaped feet rigidly attached to the legs. However, the friction torque against yaw is often insufficient because of their contact conditions with the ground. We developed a simple 3D straight-legged passive walker with flat feet and ankle springs. Flat feet were used to gain enough scrubbing friction to oppose unstable yaw motion. Springs were attached to the ankle to produce torque resulting in roll and pitch motions that mimic those of 3D passive walkers with arc-shaped feet, while the friction torque against yaw should be sufficient. The spring constant for the roll motion at the stance ankle is obviously an important factor in enabling the straight-legged robot to rock adequately from side to side to avoid problematic scuffing of the swing leg so it can swing forward. We used numerical simulations to determine the value of the spring constant. Experimental results indicated that our 3D straight-legged passive walker with a 0.77-m leg can walk more than 2 m at about 0.46 m/s.

  13. There Is a Difference between Living in a Dream and Living a Dream: A Response to Romer and Walker

    ERIC Educational Resources Information Center

    Strully, Jeffrey L.

    2013-01-01

    This article provides a response to Romer and Walker from two distinct perspectives: the field of developmental disabilities and a parent of children with developmental disabilities. Jeffrey Strully describes his current role managing a moderate-sized agency in Los Angeles that provides individualized and personalized supports as well as his work…

  14. Neuropsychological and Behavioural Phenotype of Dandy-Walker Variant Presenting in Chromosome 22 Trisomy: A Case Study

    ERIC Educational Resources Information Center

    Searson, Ruth; Hare, Dougal Julian; Sridharan, Sridhar

    2013-01-01

    In this study, a case of Dandy-Walker variant syndrome associated with trisomy 22 in a 17-year-old man is described. This is the first account of this combination in a person surviving into adulthood, and the neuropsychological and behavioural presentation is described in detail and a clinical formulation is presented for the benefit of…

  15. Description of a new species and subspecies of Idalus Walker from Costa Rica, Honduras and Guatemala (Lepidoptera, Erebidae, Arctiinae, Arctiini)

    PubMed Central

    Espinoza, Bernardo A.; Janzen, Daniel H.; Winnie Hallwachs;  J. Bolling Sullivan

    2013-01-01

    Abstract A new species and subspecies of Idalus Walker are described from Costa Rica, Honduras and Guatemala. Images of males and females and their genitalia are provided. Locality information and distribution maps for Costa Rica and for Guatemala are included. The biology and phylogeny of Idalus are discussed. PMID:23730178

  16. "It's Not so Much a Job but a Relationship": A Response to Romer and Walker

    ERIC Educational Resources Information Center

    O'Brien, John

    2013-01-01

    Romer and Walker's "Appreciative Inquiry," which obtained input from 16 capable personal assistants, challenges some influential assumptions about personal assistance and opens a way to think about the demanding work of developing capable and committed personal assistants. Attempts to depersonalize the relationship between people…

  17. Walker Branch Throughfall Displacement Experiment Data Report: Site Characterization, System Performance, Weather, Species Composition, and Growth

    SciTech Connect

    Hanson, P.J.

    2001-09-04

    This numeric data package provides data sets, and accompanying documentation, on site characterization, system performance, weather, species composition, and growth for the Throughfall Displacement Experiment, which was established in the Walker Branch Watershed of East Tennessee to provide data on the responses of forests to altered precipitation regimes. The specific data sets include soil water content and potential, coarse fraction of the soil profile, litter layer temperature, soil temperature, monthly weather, daily weather, hourly weather, species composition of trees and saplings, mature tree and sapling annual growth, and relative leaf area index. Fortran and SAS{trademark} access codes are provided to read the ASCII data files. The data files and this documentation are available without charge on a variety of media and via the Internet from the Carbon Dioxide Information Analysis Center (CDIAC).

  18. Increased central serotonergic activity associated with nocturnal anorexia induced by Walker 256 carcinoma.

    PubMed

    Nichols, M; Maickel, R P; Yim, G K

    1983-04-18

    The role of brain serotonin levels in Walker 256 tumor induced anorexia was investigated. Total and free plasma tryptophan, regional brain serotonin and 5-hydroxyindoleacetic acid were determined at night, and their relationship to nocturnal anorexia assessed by linear regression analysis. No significant difference in tryptophan, serotonin, or 5-hydroxyindoleacetic acid levels was detected between pair fed and tumor bearing rats exhibiting a 20% reduction of nighttime food intake. Tumor bearing rats with a 40% reduction in food intake had higher nighttime plasma free tryptophan and regional 5-hydroxyindoleacetic acid levels than their pair fed malnourished controls. These results indicate that increased plasma free tryptophan and elevated serotonin metabolism may not be the initial dysfunction responsible for nocturnal anorexia. However, it may contribute to the decreasing nocturnal food intake in severely anorexic tumor rats.

  19. "It feels good to be measured": clinical role-play, Walker Percy, and the tingles.

    PubMed

    Ahuja, Nitin K

    2013-01-01

    A large online community has recently formed around autonomous sensory meridian response (ASMR), a pleasant and poorly understood somatic reaction to specific interpersonal triggers. Its web-based manifestations include a variety of amateur videos designed to elicit the reaction, many of which feature protracted imitations of a clinician's physical exam. This analysis considers through a literary lens the proximity of this phenomenon to clinical diagnostics, focusing in particular on characterizations of spiritual isolation elaborated in Love in the Ruins (1971), the third novel by physician-writer Walker Percy (1916-1990). Within this speculative framework, the tendency to derive pleasure from clinical milieus, real or constructed, may be interpreted as a quality particular to the postmodern psyche. Viewing web-based clinical role-play in light of Percy's writing also underscores the possibility that routine diagnostic assessments may have independent therapeutic implications. PMID:24375123

  20. Improved gene prediction by principal component analysis based autoregressive Yule-Walker method.

    PubMed

    Roy, Manidipa; Barman, Soma

    2016-01-10

    Spectral analysis using Fourier techniques is popular with gene prediction because of its simplicity. Model-based autoregressive (AR) spectral estimation gives better resolution even for small DNA segments but selection of appropriate model order is a critical issue. In this article a technique has been proposed where Yule-Walker autoregressive (YW-AR) process is combined with principal component analysis (PCA) for reduction in dimensionality. The spectral peaks of DNA signal are used to detect protein-coding regions based on the 1/3 frequency component. Here optimal model order selection is no more critical as noise is removed by PCA prior to power spectral density (PSD) estimation. Eigenvalue-ratio is used to find the threshold between signal and noise subspaces for data reduction. Superiority of proposed method over fast Fourier Transform (FFT) method and autoregressive method combined with wavelet packet transform (WPT) is established with the help of receiver operating characteristics (ROC) and discrimination measure (DM) respectively.

  1. Associative learning of Nasonia vitripennis Walker (Hymenoptera:Pteromalidae) to methyldisulfanylmethane.

    PubMed

    Frederickx, Christine; Verheggen, François J; Brostaux, Yves; Haubruge, Eric

    2014-03-01

    Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The possibility of using parasitic wasps for detecting explosives and narcotics has been developed. Moreover, wasps are cheap to produce and can be conditioned with impressive speed for a specific chemical detection task. We examined the ability of Nasonia vitripennis Walker to learn and respond to methyldisulfanylmethane (DMDS), a volatile discriminator of cadaver. The training aimed to form an association between an unconditioned stimulus (pupae) and the conditioned stimulus (odor source). After the training, the time spent by conditioned wasps in the DMDS chamber was measured. Statistical analysis showed that the increasing concentrations involved an increase in the time spent in the chamber containing DMDS. This study indicates that N. vitripennis can respond to DMDS, which provide further support for its development as a biological sensor.

  2. On the integrability of Friedmann Robertson Walker models with conformally coupled massive scalar fields

    NASA Astrophysics Data System (ADS)

    Coelho, L. A. A.; Skea, J. E. F.; Stuchi, T. J.

    2008-02-01

    In this paper, we use a nonintegrability theorem by Morales and Ramis to analyse the integrability of Friedmann-Robertson-Walker cosmological models with a conformally coupled massive scalar field. We answer the long-standing question of whether these models with a vanishing cosmological constant and non-self-interacting scalar field are integrable: by applying Kovacic's algorithm to the normal variational equations, we prove analytically and rigorously that these equations and, consequently, the Hamiltonians are nonintegrable. We then address the models with a self-interacting massive scalar field and cosmological constant and show that, with the exception of a set of measure zero, the models are nonintegrable. For the spatially curved cases, we prove that there are no additional integrable cases other than those identified in the previous work based on the non-rigorous Painlevé analysis. In our study of the spatially flat model, we explicitly obtain a new possibly integrable case.

  3. Fast escape of a quantum walker from an integrated photonic maze.

    PubMed

    Caruso, Filippo; Crespi, Andrea; Ciriolo, Anna Gabriella; Sciarrino, Fabio; Osellame, Roberto

    2016-06-01

    Escaping from a complex maze, by exploring different paths with several decision-making branches in order to reach the exit, has always been a very challenging and fascinating task. Wave field and quantum objects may explore a complex structure in parallel by interference effects, but without necessarily leading to more efficient transport. Here, inspired by recent observations in biological energy transport phenomena, we demonstrate how a quantum walker can efficiently reach the output of a maze by partially suppressing the presence of interference. In particular, we show theoretically an unprecedented improvement in transport efficiency for increasing maze size with respect to purely quantum and classical approaches. In addition, we investigate experimentally these hybrid transport phenomena, by mapping the maze problem in an integrated waveguide array, probed by coherent light, hence successfully testing our theoretical results. These achievements may lead towards future bio-inspired photonics technologies for more efficient transport and computation.

  4. Revision of the Amazonian species of Syneches Walker (Diptera, Hybotidae, Hybotinae).

    PubMed

    Menezes, Isis Sá; Ale-Rocha, Rosaly

    2016-01-01

    A revision of the Amazonian species of Syneches Walker resulted in the re-description of four species and the description of nine new species: Syneches amazonicus sp. nov., S. angulatus sp. nov., S. applanatus sp. nov., S. bilobatus sp. nov., S. equatoriensis sp. nov., S. exilis sp. nov., S. maculosum sp. nov., S. striatus sp. nov., S. tenebricus sp. nov., and two new synonymies: S. quadricinctus (Fabricius, 1805) = S. curvipes (Fabricius, 1805) and S. hispidus Ale-Rocha & Vieira, 2008 = S. repletus Bezzi, 1909. The male of S. fuscescens Bezzi and the female of S. annulipes Bezzi are described and their terminalia are illustrated. Geographic records for S. annulipes Bezzi, S. curvipes (Fabricius), S. fuscescens Bezzi, S. manaos Smith, S. moraballi Smith, S. rafaeli Ale-Rocha & Vieira, S. repletus Bezzi and S. walkeri Smith and an identification key for the species recorded in the Amazon are provided. PMID:27394746

  5. Fast escape of a quantum walker from an integrated photonic maze

    PubMed Central

    Caruso, Filippo; Crespi, Andrea; Ciriolo, Anna Gabriella; Sciarrino, Fabio; Osellame, Roberto

    2016-01-01

    Escaping from a complex maze, by exploring different paths with several decision-making branches in order to reach the exit, has always been a very challenging and fascinating task. Wave field and quantum objects may explore a complex structure in parallel by interference effects, but without necessarily leading to more efficient transport. Here, inspired by recent observations in biological energy transport phenomena, we demonstrate how a quantum walker can efficiently reach the output of a maze by partially suppressing the presence of interference. In particular, we show theoretically an unprecedented improvement in transport efficiency for increasing maze size with respect to purely quantum and classical approaches. In addition, we investigate experimentally these hybrid transport phenomena, by mapping the maze problem in an integrated waveguide array, probed by coherent light, hence successfully testing our theoretical results. These achievements may lead towards future bio-inspired photonics technologies for more efficient transport and computation. PMID:27248707

  6. Fast escape of a quantum walker from an integrated photonic maze.

    PubMed

    Caruso, Filippo; Crespi, Andrea; Ciriolo, Anna Gabriella; Sciarrino, Fabio; Osellame, Roberto

    2016-01-01

    Escaping from a complex maze, by exploring different paths with several decision-making branches in order to reach the exit, has always been a very challenging and fascinating task. Wave field and quantum objects may explore a complex structure in parallel by interference effects, but without necessarily leading to more efficient transport. Here, inspired by recent observations in biological energy transport phenomena, we demonstrate how a quantum walker can efficiently reach the output of a maze by partially suppressing the presence of interference. In particular, we show theoretically an unprecedented improvement in transport efficiency for increasing maze size with respect to purely quantum and classical approaches. In addition, we investigate experimentally these hybrid transport phenomena, by mapping the maze problem in an integrated waveguide array, probed by coherent light, hence successfully testing our theoretical results. These achievements may lead towards future bio-inspired photonics technologies for more efficient transport and computation. PMID:27248707

  7. Growth by random walker sampling and scaling of the dielectric breakdown model

    NASA Astrophysics Data System (ADS)

    Somfai, Ellák; Goold, Nicholas R.; Ball, Robin C.; Devita, Jason P.; Sander, Leonard M.

    2004-11-01

    Random walkers absorbing on a boundary sample the harmonic measure linearly and independently: we discuss how the recurrence times between impacts enable nonlinear moments of the measure to be estimated. From this we derive a technique to simulate dielectric breakdown model growth, which is governed nonlinearly by the harmonic measure. For diffusion-limited aggregation, recurrence times are shown to be accurate and effective in probing the multifractal growth measure in its active region. For the dielectric breakdown model our technique grows large clusters efficiently and we are led to significantly revise earlier exponent estimates. Previous results by two conformal mapping techniques were less converged than expected, and in particular a recent theoretical suggestion of superuniversality is firmly refuted.

  8. Effects of field interactions upon particle creation in Robertson-Walker universes

    NASA Technical Reports Server (NTRS)

    Birrell, N. D.; Davies, P. C. W.; Ford, L. H.

    1980-01-01

    Particle creation due to field interactions in an expanding Robertson-Walker universe is investigated. A model in which pseudoscalar mesons and photons are created as a result of their mutual interaction is considered, and the energy density of created particles is calculated in model universes which undergo a bounce at some maximum curvature. The free-field creation of non-conformally coupled scalar particles and of gravitons is calculated in the same space-times. It is found that if the bounce occurs at a sufficiently early time the interacting particle creation will dominate. This result may be traced to the fact that the model interaction chosen introduces a length scale which is much larger than the Planck length.

  9. Dandy–Walker Malformation, Genitourinary Abnormalities, and Intellectual Disability in Two Families

    PubMed Central

    Gregor, Anne; Gleeson, Joseph G.; Rosti, Rasim Ozgur

    2016-01-01

    We report on two families, each with documented consanguinity and two affected with overlapping features of Dandy-Walker malformation, genitourinary abnormalities, intellectual disability, and hearing deficit. This phenotype shares similar findings with many well-known syndromes. However, the clinical findings of this syndrome categorize this as a new syndrome as compared with the phenotype of already established syndromes. Due to parental consanguinity, occurrence in siblings of both genders and the absence of manifestations in obligate carrier parents, an autosomal recessive pattern of inheritance is more likely. The authors believe that these families suggest a novel autosomal recessive cerebello–genital syndrome. Array CGH analyses of an affected did not show pathological deletions or duplications. PMID:26109232

  10. "It feels good to be measured": clinical role-play, Walker Percy, and the tingles.

    PubMed

    Ahuja, Nitin K

    2013-01-01

    A large online community has recently formed around autonomous sensory meridian response (ASMR), a pleasant and poorly understood somatic reaction to specific interpersonal triggers. Its web-based manifestations include a variety of amateur videos designed to elicit the reaction, many of which feature protracted imitations of a clinician's physical exam. This analysis considers through a literary lens the proximity of this phenomenon to clinical diagnostics, focusing in particular on characterizations of spiritual isolation elaborated in Love in the Ruins (1971), the third novel by physician-writer Walker Percy (1916-1990). Within this speculative framework, the tendency to derive pleasure from clinical milieus, real or constructed, may be interpreted as a quality particular to the postmodern psyche. Viewing web-based clinical role-play in light of Percy's writing also underscores the possibility that routine diagnostic assessments may have independent therapeutic implications.

  11. A systematic study of Ichneumonosoma de Meijere, Pelmatops Enderlein, Pseudopelmatops Shiraki and Soita Walker (Diptera: Tephritidae).

    PubMed

    Chen, Xiao-Lin; Norrbom, Allen; Freidberg, Amnon; Chesters, Douglas; Islam, Md Sajedul; Zhu, Chao-Dong

    2015-09-09

    Four fruit fly genera, Ichneumonosoma de Meijere, Pelmatops Enderlein, Pseudopelmatops Shiraki and Soita Walker, were studied and 19 species are recognized. Three new species, Soita infuscata Chen & Norrbom, Ichneumonosoma quadripunctata Chen & Freidberg, and I. triangularis Chen & Norrbom are described and illustrated. Ichneumonosoma and Soita are revised, and keys to all the species are provided. Ichneumonosoma imitans (de Meijere) is newly recorded from Thailand. One new synonym is established: Soita Walker = Xaniosternum Enderlein, and Xaniosternum ophioneum Enderlein is moved from Xaniosternum to Soita (n. comb.). In addition, new morphological, geographic and biological information for two stalk-eyed fruit fly genera, Pelmatops and Pseudopelmatops, are provided. Pelmatops fukienensis Zia & Chen is newly recorded from Burma, Pelmetops ichneumoneus (Westwood) is newly recorded from Thailand and Burma, Pseudopelmatops angustifasciatus Zia & Chen is newly recorded from Vietnam, and the male of P. angustifasciatus is described and illustrated for the first time. The morphology of the compound eye and occipital protuberance of Pelmatops and Pseudopelmatops is described and illustrated for the first time. A cladistic analysis based on morphological characters of adults, a partial molecular analysis using the nuclear 28S rDNA (28S) and the mitochondrial cytochrome c oxidase I (COI) genes and a combined dataset were conducted to reconstruct the phylogeny of the four genera and their species. The results showed good support for monophyly of each of the four genera and the clade of the stalk-eyed fruit flies (Pelmatops + Pseudopelmatops). However, relationships of the stalk-eyed fruit flies with Soita and Ichneumonosoma are not clearly resolved, with the morphological analysis indicating that Ichneumonosoma is the sister group of the stalk-eyed fruit flies, but the 28S analysis and the combined analysis group Soita closer to the stalk-eyed fruit flies. Regarding

  12. 1989 Walker Branch Watershed Surveying and Mapping Including a Guide to Coordinate Transformation Procedures

    SciTech Connect

    Timmins, S.

    1991-01-01

    Walker Branch Watershed is a forested, research watershed marked throughout by a 264 ft grid that was surveyed in 1967 using the Oak Ridge National Laboratory (X-10) coordinate system. The Tennessee Valley Authority (TVA) prepared a contour map of the watershed in 1987, and an ARC/INFO{trademark} version of the TVA topographic map with the X-10 grid superimposed has since been used as the primary geographic information system (GIS) data base for the watershed. However, because of inaccuracies observed in mapped locations of some grid markers and permanent research plots, portions of the watershed were resurveyed in 1989 and an extensive investigation of the coordinates used in creating both the TVA map and ARC/INFO data base and of coordinate transformation procedures currently in use on the Oak Ridge Reservation was conducted. They determined that the positional errors resulted from the field orientation of the blazed grid rather than problems in mapmaking. In resurveying the watershed, previously surveyed control points were located or noted as missing, and 25 new control points along the perimeter roads were surveyed. In addition, 67 of 156 grid line intersections (pegs) were physically located and their positions relative to mapped landmarks were recorded. As a result, coordinates for the Walker Branch Watershed grid lines and permanent research plots were revised, and a revised map of the watershed was produced. In conjunction with this work, existing procedures for converting between the local grid systems, Tennessee state plane, and the 1927 and 1983 North American Datums were updated and compiled along with illustrative examples and relevant historical information. Alternative algorithms were developed for several coordinate conversions commonly used on the Oak Ridge Reservation.

  13. Binding of formyl peptides to Walker 256 carcinosarcoma cells and the chemotactic response of these cells

    SciTech Connect

    Rayner, D.C.; Orr, F.W.; Shiu, R.P.

    1985-05-01

    N-Formylmethionylleucylphenylalanine (fMLP) induces chemotaxis in leukocytes, the response being mediated by peptide binding to a receptor on the plasma membrane. In tumor cells, this peptide has been reported to induce cellular swelling and chemotaxis in vitro and to enhance the localization of circulating tumor cells in vivo. In the Boyden chamber, the authors evaluated the migratory responses of Walker carcinosarcoma 256 cells to varying concentrations of fMLP. Sigmoidal dose-response curves were obtained with the dose of chemotactic factor that elicits a half-maximal chemotactic response of 5.0 +/- 2.5 X 10(-8) M. Checkerboard analysis indicated that these responses were dependent upon a concentration gradient of fMLP with increases in migration of circa 2 to 2.5 times that of random movement. To examine the binding of fMLP, the tumor cells were incubated with 5 X 10(-9) M fML-(/sup 3/H)P in Hanks balanced salt solution. Specific binding (0.5 to 1% of total radioligand, to whole cells inhibited by 5 X 10(-6) M fMLP) approached equilibrium after 4 to 6 h at 4 degrees C and after 6 to 10 h at 22 degrees C. Autoradiographic studies demonstrated heterogeneous binding of the peptide by tumor cells and also showed its intracellular localization. In homogenates of Walker cells prepared in 0.1 M Tris HCl, pH 7.4, with 10 mM MgCl2 and bovine serum albumin (1 mg/ml), specific binding of approximately 0.5% of total fML-(/sup 3/H)P reached equilibrium after 60 min at 4 degrees C. In whole cells and homogenates, binding was reversible by addition of unlabeled fMLP.

  14. Assessment of Bathymetry and Sediment Accumulation of Walker Lake, PA with Multiple Frequency GPR Antennas

    NASA Astrophysics Data System (ADS)

    Lachhab, A.; Booterbaugh, A.; Beren, M.

    2012-12-01

    Silting within all man-made reservoirs, can be a major problem. Exploring bathymetry with electromagnetic prospection tools is one way to identify the magnitude of sediment accumulation in lakes and reservoirs. In this study, the bathymetry and sediment accumulation of Walker Lake, PA was explored via multi-frequency ground penetrating radar (GPR) surveys. Walker Lake is located on the North Branch Middle Creek, which is a tributary to Middle Creek within the Susquehanna River basin. The technique developed in this study included two antennas positioned on a medium size inflatable boat towed by a 14' flat-bottom Jon Boat. Both 400 and 100 MHz antennas were deployed and sediment thickness and distribution throughout the lake were identified. A total of eighteen transects were taken along the entire length of the lake. A new method with multiple approaches including RADAN 7, GPR Viewer, SAS 9.1.3 and MATLAB was developed to generate three-Dimensional and contour surface of the pre-1971 Topography and bathymetry based on GPR reflection readings. As a result, depth, accumulation and rate of sedimentation in the lake were successfully measured. The lake was found to vary between 0.5 to 9 meters in depth. Sediment accumulation and distribution were calculated from the difference between the surveyed bathymetry and the 1971 pre-existent landscape topography. Sediment was found to accumulate thickest within the old channel of Middle Creek however, the bulk of the sediment volume lied outside this channel. Sediment deposition accumulates mainly upstream near the inlet to the lake and gradually decreases toward the dam inversely proportional to the depth of the lake.

  15. Participation of the NO/cGMP/K+ATP pathway in the antinociception induced by Walker tumor bearing in rats.

    PubMed

    Barbosa, A L R; Pinheiro, C A; Oliveira, G J; Torres, J N L; Moraes, M O; Ribeiro, R A; Vale, M L; Souza, M H L P

    2012-06-01

    Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K(+)ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K(+)ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220 g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E(2)- (PGE(2), 400 ng/paw; 50 µL; intraplantar injection) and carrageenan-induced hypernociception (500 µg/paw; 100 µL; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE(2)) by a selective inhibitor of nitric oxide synthase (L-NAME; 90 mg/kg, ip) and L-arginine (200 mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE(2)) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE(2); 8 µg/paw) and the ATP-sensitive K(+) channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE(2); 160 µg/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels. PMID:22450376

  16. Reference Directions, Rotations, and Magnetostratigraphy: Utilization of Oligocene Ignimbrite Paleomagnetism to Better Understand Walker Lane Tectonics, Western Nevada, USA

    NASA Astrophysics Data System (ADS)

    Carlson, C. W.; Faulds, J. E.

    2015-12-01

    The Walker Lane accommodates ~20% of dextral strain between the Pacific and North American Plates on discontinuous sets of predominately northwest-striking right- and easterly striking left-lateral faults. Located west of dextral faults of the central Walker Lane and east of the Sierra Nevada frontal fault system is a region of normal faults and asymmetric basins where geodetic studies define ~5 mm/yr of northwest-directed dextral strain. As this region is devoid of major strike-slip fault systems, how strain is accommodated is poorly understood. To elucidate the long-term tectonic development of this region, we are compiling paleomagnetic data from late Oligocene ash-flow tuffs to determine magnitudes of vertical-axis rotation. This data set will be compared with ongoing and complementary studies of subsurface basin geometry and recent fault-slip motions to ultimately understand the tectonic development of this enigmatic part of the Walker Lane.Paleomagnetic directions were collected from structural-blocks where multiple ash-flow tuffs crop out in stratigraphic succession, and at least one sampled unit has a previously established reference direction. This approach will allow for determination of the magnitude of vertical-axis rotation at each locality and provide an opportunity to infer paleomagnetic reference directions for other ash-flow tuffs. Preliminary paleomagnetic data have identified statistically-significant magnitudes of vertical-axis rotation (~20-50° clockwise) west of central Walker Lane dextral faults. Magnetostratigraphic correlations to the geomagnetic time scale have refined ages for several ash-flow tuffs, and span ~5 Ma of the late Oligocene (chrons: 6Cn.3n-10r). The results of this research will not only elucidate the manner in which dextral shear is accommodated in this portion of the Walker Lane, but also provide an extensive data set for establishing Oligocene ash-flow tuff paleomagnetic reference directions and regional correlations.

  17. Organic geochemistry and brine composition in Great Salt, Mono, and Walker Lakes

    NASA Astrophysics Data System (ADS)

    Domagalski, Joseph L.; Orem, William H.; Eugster, Hans P.

    1989-11-01

    Samples of Recent sediments, representing up to 1000 years of accumulation, were collected from three closed basin lakes (Mono Lake, CA, Walker Lake, NV, and Great Salt Lake, UT) to assess the effects of brine composition on the accumulation of total organic carbon, the concentration of dissolved organic carbon, humic acid structure and diagenesis, and trace metal complexation. The Great Salt Lake water column is a stratified Na-Mg-Cl-SO 4 brine with low alkalinity. Algal debris is entrained in the high density (1.132-1.190 g/cc) bottom brines, and in this region maximum organic matter decomposition occurs by anaerobic processes, with sulfate ion as the terminal electron acceptor. Organic matter, below 5 cm of the sediment-water interface, degrades at a very slow rate in spite of very high pore-fluid sulfate levels. The organic carbon concentration stabilizes at 1.1 wt%. Mono Lake is an alkaline (Na-CO 3-Cl-SO 4) system. The water column is stratified, but the bottom brines are of lower density relative to the Great Salt Lake, and sedimentation of algal debris is rapid. Depletion of pore-fluid sulfate, near l m of core, results in a much higher accumulation of organic carbon, approximately 6 wt%. Walker Lake is also an alkaline system. The water column is not stratified, and decomposition of organic matter occurs by aerobic processes at the sediment-water interface and by anaerobic processes below. Total organic carbon and dissolved organic carbon concentrations in Walker Lake sediments vary with location and depth due to changes in input and pore-fluid sulfate concentrations. Nuclear magnetic resonance studies ( 13C) of humic substances and dissolved organic carbon provide information on the source of the Recent sedimentary organic carbon (aquatic vs. terrestrial), its relative state of decomposition, and its chemical structure. The spectra suggest an algal origin with little terrestrial signature at all three lakes. This is indicated by the ratio of aliphatic to

  18. Organic geochemistry and brine composition in Great Salt, Mono, and Walker Lakes

    USGS Publications Warehouse

    Domagalski, J.L.; Orem, W.H.; Eugster, H.P.

    1989-01-01

    Samples of Recent sediments, representing up to 1000 years of accumulation, were collected from three closed basin lakes (Mono Lake, CA, Walker Lake, NV, and Great Salt Lake, UT) to assess the effects of brine composition on the accumulation of total organic carbon, the concentration of dissolved organic carbon, humic acid structure and diagenesis, and trace metal complexation. The Great Salt Lake water column is a stratified Na-Mg-Cl-SO4 brine with low alkalinity. Algal debris is entrained in the high density (1.132-1.190 g/cc) bottom brines, and in this region maximum organic matter decomposition occurs by anaerobic processes, with sulfate ion as the terminal electron acceptor. Organic matter, below 5 cm of the sediment-water interface, degrades at a very slow rate in spite of very high pore-fluid sulfate levels. The organic carbon concentration stabilizes at 1.1 wt%. Mono Lake is an alkaline (Na-CO3-Cl-SO4) system. The water column is stratified, but the bottom brines are of lower density relative to the Great Salt Lake, and sedimentation of algal debris is rapid. Depletion of pore-fluid sulfate, near l m of core, results in a much higher accumulation of organic carbon, approximately 6 wt%. Walker Lake is also an alkaline system. The water column is not stratified, and decomposition of organic matter occurs by aerobic processes at the sediment-water interface and by anaerobic processes below. Total organic carbon and dissolved organic carbon concentrations in Walker Lake sediments vary with location and depth due to changes in input and pore-fluid sulfate concentrations. Nuclear magnetic resonance studies (13C) of humic substances and dissolved organic carbon provide information on the source of the Recent sedimentary organic carbon (aquatic vs. terrestrial), its relative state of decomposition, and its chemical structure. The spectra suggest an algal origin with little terrestrial signature at all three lakes. This is indicated by the ratio of aliphatic to

  19. Lithology, Geochemistry and Paleomagnetism of the Table Mountain Formation at the Little Walker Caldera

    NASA Astrophysics Data System (ADS)

    Schubert, R.; Pluhar, C. J.; Carlson, C. W.; Jones, S. A.

    2015-12-01

    West of Bridgeport Valley near the Central Sierra Nevada crest, the Little Walker Caldera (LWC) erupted Stanislaus Group lavas and tuffs during the Late Miocene. Remnants of these rocks are now distributed from the western Sierra Nevada foothills across the range and into the Walker Lane. This wide distribution is attributed to the lavas flowing down paleochannels, which provide an excellent marker for deformation over the last 10 Ma. Priest (1978) identified a thick section of these lavas along Flatiron Ridge, the southeast margin of the LWC, which our preliminary data suggests may correlate with lavas in the Sweetwater Mountains to the northeast and at Rancheria Mtn near Hetch Hetchy to the southwest. The oldest unit in the Stanislaus group is the Table Mountain Formation, a trachyandesite. At Priest's measured section it is divided into three members. By our measurements, the Lower Member (Tmtl) is 256 meters thick, has a fine-grained groundmass with plagioclase and augite phenocrysts (<0.5 cm), and the presence of augite phenocrysts distinguishes it from the other members. Some Tmtl flows have chalcedony amigdules. Overlying this, the Large Plagioclase member (Tmtp) is 43.5 meters thick. Distinguished by (~1 cm) plagioclase and occasional small olivine phenocrysts. The Upper Member (Tmtu) is 116 meters thick, very fine-grained and often platy. Tmtl has a distinctive northwest-oriented normal polarity and geochemistry, similar to several localities at Rancheria Mtn. Tmtu has a reversed polarity similar to the polarity of Table Mountain Formation in the Sweetwater Mountains and lavas that directly underlie the ~9.5 Ma Tollhouse Flat member of the Eureka Valley Tuff at Rancheria Mtn. Thus, our preliminary data suggest that the lower member at Priest's Measured Section could correlate to the normal polarity samples at Rancheria Mtn. Also, that the upper Member reversed-polarity samples may correlate with lavas both at the Sweetwater Mountains and Rancheria Mtn

  20. Field Studies of Streamflow Generation Using Natural and Injected Tracers on Bickford and Walker Branch Watersheds

    SciTech Connect

    Genereux, D.

    1992-01-01

    Field studies of streamflow generation were undertaken on two forested watersheds, the West Road subcatchment of Bickford Watershed in central Massachusetts and the West Fork of Walker Branch Watershed in eastern Tennessee. A major component of the research was development of a two-stage methodology for the use of naturally-occurring {sup 222}Rn as a tracer. The first of the two stages was solving a mass-balance equation for {sup 222}Rn around a stream reach of interest in order to calculate [Rn]{sub q}, the {sup 222}Rn content of the lateral inflow to the reach; a conservative tracer (chloride) and a volatile tracer (propane) were injected into the study stream to account for lateral inflow to, and {sup 222}Rn volatilization from, the study reach. The second stage involved quantitative comparison of [Rn]{sub q} to the measured {sup 222}Rn concentrations of different subsurface waters in order to assess how important these waters were in contributing lateral inflow to the stream reach. The method was first applied to a 34 m stream reach at Bickford during baseflow; results suggested that {ge} 70% of the lateral inflow could be considered vadose zone water (water which had been in a saturated zone for less than a few days), and the remainder ''soil groundwater'' or ''saturated zone water'' (which had a longer residence time in a soil saturated zone). The method was then applied to two stream reaches on the West Fork of Walker Branch over a wide range of flow conditions; four springs were also investigated. It was found that springwater and inflow to the stream could be viewed as a mixture of water from three end members: the two defined at Bickford (vadose zone water and soil groundwater) and a third (bedrock groundwater) to account for the movement of water through fractured dolomite bedrock. Calcium was used as a second naturally-occurring tracer to distinguish bedrock groundwater from the other two end members. The behavior indicated by the three

  1. B-29 mothership with pilots - Payne, Butchart, Walker, Littleton, and Moise

    NASA Technical Reports Server (NTRS)

    1953-01-01

    This photo shows the B-29 in the background with Dick Payne, Stan Butchart, and Joe Walker standing in front of it, Charles Littleton and John Moise squatting. The Boeing B-29 was the first U.S. aircraft to be modified to serve as an airborne launch vehicle. Last operated by the NASA High-Speed Flight Station (now the Dryden Flight Research Center, Edwards, California), the B-29 aircraft was used to launch the X-1 series aircraft, including the X-1-1, the X-1-2 (later redesignated the X-1E), the X-1A, and the X-1B. The B-29, which was accepted by the Air Force on Aug. 2, 1945, was operated by the NACA, NASA, the U.S. Air Force, and the Bell Aircraft Company. The Air Force transferred the B-29 to Bell Aircraft Company where it was modified to act as a carrier, or 'mothership,' for the first X-1. After modification, the aircraft flew to Pinecastle Army Air Base, Florida, where it made aeronautical history on Jan. 25, 1946, with its air launch of the first X-1. It then performed 10 drops of the X-1 at Pinecastle before flying to Edwards Air Force Base, California, in September 1946 where it dropped the X-1 for its first powered flight on Dec. 9, 1946. On Oct. 14, 1947, the B-29 again participated in a major aeronautical advance when it air launched the X-1 aircraft, which proceeded to exceed the speed of sound (Mach 1) for the first time. Air Force Pilot Captain Charles 'Chuck' Yeager was at the controls of the X-1 that day. A mid-air explosion in the 'captive' X-1A almost ended the career of the B-29 on Aug. 8, 1955. But pilot Stanley P. Butchart dropped the X-1A to its destruction in the desert after X-1A pilot, Joseph A. Walker, had scrambled back into the B-29. The B-29's 14-year career ended on July 1, 1959, when it was flown from the NASA High-Speed Flight Station to Davis-Monthan Air Force Base, Arizona, for retirement. The aircraft was made obsolete as a mothership by the advent of the X-15 Program, which required a larger, faster launch vehicle, the B-52. In

  2. Sonographic findings in a case of tetrasomy 9p associated with increased nuchal translucency and Dandy-Walker malformation.

    PubMed

    Nakamura-Pereira, Marcos; Cima, Luciana Carneiro do; Llerena, Juan Clinton; Guerra, Fernando Antonio Ramos; Peixoto-Filho, Fernando Maia

    2009-10-01

    We report a case of a 23-year-old pregnant woman, who underwent amniocentesis after ultrasound (US) examination in the first trimester which revealed a nuchal translucency thickness of 2.9 mm. Cytogenetic analysis revealed complete tetrasomy of the short arm of chromosome 9. Further US evaluation in the second trimester revealed Dandy-Walker malformation, ventriculomegaly, bilateral clubfoot, lip and palate clefts, arthrogryposis and hyperechoic kidneys with bilateral pelvic dilatation. At 30 weeks of gestation, a placental abruption was noted and a Cesarean section was performed. The infant died shortly after birth. A review of previous cases of tetrasomy 9p shows that the remarkable sonographic findings are ventriculomegaly, intrauterine growth restriction, genitourinary anomaly, Dandy-Walker malformation, cleft lip/palate and limb malformation, but the association of tetrasomy 9p and increased nuchal translucency had not been reported. PMID:19655321

  3. Circadian variations in 32P uptake of DMBA-induced mammary tumour and Walker carcinosarcoma in rats.

    PubMed Central

    Møoller, U.; Bojsen, J.

    1976-01-01

    The 32P uptake in a mammary tumour induced by DMBA and in the Walker 256 carcinosarcoma was measured by external GM -tubes. The uptake was significantly higher than in the skin. During exposure to a synchronized light regime a circadian variation was present in the 32P uptake of the hormone-dependent DMBA-induced tumour. The maximal 32P uptake was in the dark period, in which the highest temperature in the tumour has also been found (Møoller and Bojsen, 1975). In the hormone-independent Walker 256 carcinosarcoma there was no periodicity in 32P uptake. No variation in 32P uptake was registered in the skin of normal controls or in tumour-bearing rats. PMID:820364

  4. Superfund Record of Decision (EPA Region 4): Mathis Brothers Landfill (South Marble Top Road), Walker County, GA, March 1993

    SciTech Connect

    Not Available

    1993-03-01

    This decision document (Record of Decision) presents the selected remedial action for the Mathis Brothers - South Marble Top Road Landfill site, Walker County, Georgia. At this time the remedial action is proposed as both the first, and the final remedial action for the site. The function of this remedy is to treat contamination and reduce it to health based levels. Source material and contaminated soils are the principal threat at the site.

  5. Nonlinear structural analysis of a turbine airfoil using the Walker viscoplastic material model for B1900 + Hf

    NASA Technical Reports Server (NTRS)

    Meyer, T. G.; Hill, J. T.; Weber, R. M.

    1988-01-01

    A viscoplastic material model for the high temperature turbine airfoil material B1900 + Hf was developed and was demonstrated in a three dimensional finite element analysis of a typical turbine airfoil. The demonstration problem is a simulated flight cycle and includes the appropriate transient thermal and mechanical loads typically experienced by these components. The Walker viscoplastic material model was shown to be efficient, stable and easily used. The demonstration is summarized and the performance of the material model is evaluated.

  6. Gaussian approximation of lambdaphi/sup 4/ theory in (3+1)-dimensional spatially flat Robertson-Walker space

    SciTech Connect

    Pohle, H.

    1989-03-15

    We investigate lambdaphi/sup 4/ theory within the Gaussian approximation in spatially flat Robertson-Walker space in 3+1 dimensions. After having performed an adiabatic expansion for one of the ansatz functions, we find that the renormalization of the energy-momentum tensor provides two additional constraints which have to be satisfied by the bare couplings. These conditions force the theory to be trivial after renormalization.

  7. Class of solutions of the Wheeler-DeWitt equation in the Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Vieira, H. S.; Bezerra, V. B.

    2016-07-01

    We show that the solutions of the Wheeler-DeWitt equation in a homogeneous and isotropic universe are given by triconfluent Heun functions for the spatially closed, flat, and open geometries of the Friedmann-Robertson-Walker universe filled with different forms of energy. In a matter-dominated universe, we find the polynomial solution and the energy density spectrum. In the cases of radiation-dominated and vacuum universes, there are no polynomial solutions as shown.

  8. Taxonomic study of the genus Thisizima Walker, 1864 in China, with descriptions of two new species (Lepidoptera, Tineidae)

    PubMed Central

    Yang, Linlin; Li, Houhun; Kendrick, Roger C.

    2012-01-01

    Abstract The taxonomic study of the genus Thisizima Walker, 1864 is carried out in China. Thisizima subceratella sp. n. and Thisizima fasciaria sp. n. are described as new based on the specimens collected in Fujian, Hainan and Hong Kong. Detailed male and female genitalia are described for the first time for the genus. Photographs of adults and genital structures are provided. A checklist of all the described species is included. PMID:23378819

  9. Effect of three hours race walk on energy cost, cardiorespiratory parameters and stride duration in elite race walkers.

    PubMed

    Brisswalter, J; Fougeron, B; Legros, P

    1996-04-01

    The purpose of this study was to quantify changes in energy cost of walking (C), ventilation (VE), respiratory frequency (RF), heart rate (HR), expiratory ratio (RER), blood lactate concentration (LA), body mass (W) and stride duration (SD) after a 3 hour race walk at competition pace in elite race walkers. Subjects were tested during 2 submaximal treadmill tests at 12.2 +/- 0.5 km.h(-1) (74.7% VO2max speed) before and after a 3 hour overground walk. Significant increases (p < 0.05) were found in C, HR and significant decreases were found in RER, W, VE whereas no changes were observed in LA or SD (means and intra-subject variability). However, a wide range of individual coefficients of variation were observed for C, VE, RF, HR, SD, W. These results suggest that in well trained walkers the energy cost of walking increases with exercise duration but that walkers are able to maintain the same stride duration after the test when treadmill speed is controlled. Furthermore, some individuals appear to be more sensitive to fatigue. Discussion set out a possible effect of substrate utilisation changes, thermoregulation or a decrease in mechanical efficiency for maintaining the race walk gait apart from the effect of fatigue.

  10. Bicycle Helmet Wearing Is Not Associated with Close Motor Vehicle Passing: A Re-Analysis of Walker, 2007

    PubMed Central

    Olivier, Jake; Walter, Scott R.

    2013-01-01

    Objectives To re-analyse bicycle overtaking data collected by Walker (2007) with a view to assess factors associated with close passing (<1 m), to adjust for other observed factors in a multivariable analysis, and to assess the extent to which the sample size in the original analysis may have contributed to spurious results. Method A re-analysis of 2,355 motor vehicle passing events recorded by Walker that includes information on cyclist's distance to the kerb, vehicle size and colour, city of observation, time of day, whether the event occurred while in a bikelane and helmet wearing. Each variable was considered for a final, multivariable model using purposeful selection of variables. The analysis was repeated using multiple logistic regression with passing distance dichotomised by the one metre rule. Bootstrap p-values were computed using sample sizes computed from conventional values of power and effect size. Results The previously observed significant association between passing distance and helmet wearing was not found when dichotomised by the one metre rule. Other factors were found to be significantly associated with close passing including cyclists' distance to the kerb, vehicle size and city of observation (Salisbury or Bristol, UK). P-values from bootstrap samples indicate the significance of helmet wearing resulted from an overly large sample size. Conclusions After re-analysis of Walker's data, helmet wearing is not associated with close motor vehicle passing. The results, however, highlight other more important factors that may inform effective bicycle safety strategies. PMID:24086528

  11. Fitness test profiles and trainng intensities in skilled race-walkers.

    PubMed

    Reilly, T; Hopkins, J; Howlett, N

    1979-06-01

    A broad profile of national standard race-walkers was obtained. Subjects were taller and had more body fat than competitive runners of comparable distance as found in the literature. Pulmonary function, blood pressure and maximal heart rates were similar to normal sedentary values. The group's somatotype was 2.5 : 3 : 4, low mesomorphy being reflected in inferior strength measures. Haematological status corresponded to the runners of Brotherhood et al (1975). Predicted VO2 max (x = 70 ml kg min-1) was not related to performance. Time to exhaustion on a treadmill test correlated with 20 km race time (R = -.94; p less than .001). Multiple regression equations derived to predict race performance from combinations of 4 to 6 personality traits were non-significant. Mean heart rate in typical training regimes was 167 beats min-1 for interval training at 13 kmh-1 on the track and 134 beats min-1 over a 2.1 h road walk at 10.3 kmh-1. Physiological strain was greater in uphill than in level or downhill walking (P less than .001).

  12. Nocturnal depletion of hypothalamic dynorphin in anorexic Walker-256 tumor-bearing rats.

    PubMed

    Steele, T D; Bryant, H U; Malven, P V; Yim, G K

    1988-03-01

    Rats implanted with the Walker-256 (W-256) tumor exhibit marked anorexia that is most apparent at night. In this model, the hypothalamic kappa opioid system was examined for deficits that might contribute to this tumor-induced anorexia. In anorexic tumor-bearing rats (TBR), nocturnal levels of ir-DYN-8 were significantly reduced in the hypothalamus, but ir-DYN-17 levels were not. Accumulation of 3H-etorphine or 3H-ethylketocyclazocine, a putative ligand for the kappa receptor subtype, was not increased in the hypothalamus of the TBR, as might have been expected if there were less endogenous dynorphin to occupy the opioid receptors in this region. In vitro binding assays with 3H-ethylketocyclazocine indicated that dynorphin depletion in the TBR was not sufficient to increase the numbers of kappa opioid receptors in the hypothalamus. Also, the sensitivity of kappa opioid receptors involved in feeding was not altered in the TBR as indicated by an intact feeding response to ketocyclazocine. In summary, the marginal deficits of hypothalamic dynorphin in W-256 tumor-bearing rats that coincide with the phase of tumor-induced anorexia may contribute to the reduction in food intake.

  13. The Walker 256 Breast Cancer Cell- Induced Bone Pain Model in Rats

    PubMed Central

    Shenoy, Priyank A.; Kuo, Andy; Vetter, Irina; Smith, Maree T.

    2016-01-01

    The majority of patients with terminal breast cancer show signs of bone metastasis, the most common cause of pain in cancer. Clinically available drug treatment options for the relief of cancer-associated bone pain are limited due to either inadequate pain relief and/or dose-limiting side-effects. One of the major hurdles in understanding the mechanism by which breast cancer causes pain after metastasis to the bones is the lack of suitable preclinical models. Until the late twentieth century, all animal models of cancer induced bone pain involved systemic injection of cancer cells into animals, which caused severe deterioration of animal health due to widespread metastasis. In this mini-review we have discussed details of a recently developed and highly efficient preclinical model of breast cancer induced bone pain: Walker 256 cancer cell- induced bone pain in rats. The model involves direct localized injection of cancer cells into a single tibia in rats, which avoids widespread metastasis of cancer cells and hence animals maintain good health throughout the experimental period. This model closely mimics the human pathophysiology of breast cancer induced bone pain and has great potential to aid in the process of drug discovery for treating this intractable pain condition. PMID:27630567

  14. Shrinkage activates a nonselective conductance: involvement of a Walker-motif protein and PKC.

    PubMed

    Nelson, D J; Tien, X Y; Xie, W; Brasitus, T A; Kaetzel, M A; Dedman, J R

    1996-01-01

    The ability of all cells to maintain their volume during an osmotic challenge is dependent on the regulated movement of salt and water across the plasma membrane. We demonstrate the phosphorylation-dependent gating of a nonselective conductance in Caco-2 cells during cellular shrinkage. Intracellular application of exogenous purified rat brain protein kinase C (PKC) resulted in the activation of a current similar to that activated during shrinkage with a Na(+)-to-Cl- permeability ratio of approximately 1.7:1. To prevent possible PKC- and/or shrinkage-dependent activation of cystic fibrosis transmembrane regulator (CFTR), which is expressed at high levels in Caco-2 cells, a functional anti-peptide antibody, anti-CFTR505-511, was introduced into the cells via the patch pipette. Anti-CFTR505-511, which is directed against the Walker motif in the first nucleotide binding fold of CFTR, prevented the PKC/shrink-age current activation. The peptide CFTR505-511 also induced current inhibition, suggesting the possible involvement of a regulatory element in close proximity to the channel that shares sequence homology with the first nucleotide binding fold of CFTR and whose binding to the channel is required for channel gating. PMID:8772443

  15. The Walker 256 Breast Cancer Cell- Induced Bone Pain Model in Rats.

    PubMed

    Shenoy, Priyank A; Kuo, Andy; Vetter, Irina; Smith, Maree T

    2016-01-01

    The majority of patients with terminal breast cancer show signs of bone metastasis, the most common cause of pain in cancer. Clinically available drug treatment options for the relief of cancer-associated bone pain are limited due to either inadequate pain relief and/or dose-limiting side-effects. One of the major hurdles in understanding the mechanism by which breast cancer causes pain after metastasis to the bones is the lack of suitable preclinical models. Until the late twentieth century, all animal models of cancer induced bone pain involved systemic injection of cancer cells into animals, which caused severe deterioration of animal health due to widespread metastasis. In this mini-review we have discussed details of a recently developed and highly efficient preclinical model of breast cancer induced bone pain: Walker 256 cancer cell- induced bone pain in rats. The model involves direct localized injection of cancer cells into a single tibia in rats, which avoids widespread metastasis of cancer cells and hence animals maintain good health throughout the experimental period. This model closely mimics the human pathophysiology of breast cancer induced bone pain and has great potential to aid in the process of drug discovery for treating this intractable pain condition. PMID:27630567

  16. Development and Leaf Consumption by Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) Reared on Leaves of Agroenergy Crops.

    PubMed

    Cabezas, M F; Nava, D E; Geissler, L O; Melo, M; Garcia, M S; Krüger, R

    2013-12-01

    Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) is a polyphagous pest that threatens more than 24 species of crop plants including those used for biodiesel production such as Ricinus communis (castor bean), Jatropha curcas (Barbados nut), and Aleurites fordii (tung oil tree). The development and leaf consumption by S. cosmioides reared on leaves of these three species were studied under controlled laboratory conditions. The egg-to-adult development time of S. cosmioides was shortest when reared on castor bean leaves and longest when reared on tung oil tree leaves. Larvae reared on castor bean and Barbados nut leaves had seven instars, whereas those reared on tung oil tree leaves had eight. Females originating from larvae reared on castor bean and Barbados nut leaves showed greater fecundity than did females originating from larvae reared on tung oil tree leaves. Insects fed on castor bean leaves had shorter life spans than those fed on tung oil tree and Barbados nut leaves although the oviposition period did not differ significantly. The intrinsic and finite rates of increase were highest for females reared on castor bean leaves. Total leaf consumption was highest for larvae reared on tung oil tree leaves and lowest for those reared on Barbados nut leaves. We conclude that castor bean is a more appropriate host plant for the development of S. cosmioides than are Barbados nut and tung oil tree.

  17. Field studies of streamflow generation using natural and injected tracers on Bickford and Walker Branch Watersheds

    SciTech Connect

    Genereux, D.; Hemond, H.; Mulholland, P.

    1992-05-01

    Field studies of streamflow generation were undertaken on two forested watersheds, the West Road subcatchment of Bickford Watershed in central Massachusetts and the West Fork of Walker Branch Watershed in eastern Tennessee. A major component of the research was development of a two-stage methodology for the use of naturally-occurring {sup 222}Rn as a tracer. The first of the two stages was solving a mass-balance equation for {sup 222}Rn around a stream reach of interest in order to calculate Rn{sub q}, the {sup 222}Rn content of the lateral inflow to the reach; a conservative tracer (chloride) and a volatile tracer (propane) were injected into the study stream to account for lateral inflow to, and volatilization from, the study reach. The second stage involved quantitative comparison of Rn{sub q} to the measured {sup 222}Rn concentrations of different subsurface waters in order to assess how important these waters were in contributing lateral inflow to the stream reach.

  18. [Effects of temperature stress on physiological indices of Chilo suppressalis Walker (Lepidoptera: Pyralidae) diapause larvae].

    PubMed

    Qiang, Cheng-Kui; Du, Yu-Zhou; Yu, Ling-Ya; Qin, Yue-Hua; Feng, Wu-Jian

    2012-05-01

    To understand the physiological mechanisms of temperature stress on the diapause larvae of rice stem borer Chilo suppressalis Walker at physiological and biochemical levels, determinations were made on the contents of water, lipid, total sugar and low molecular mass carbohydrates and the activities of SOD, POD, CAT in the larvae after series temperature stress (STS) and gradient temperature stress (GTS). With the decrease of temperature, the water content in the larvae decreased, and the decrement below 0 degrees C was significantly larger in treatment GTS than in treatment STS. The lipid content in the larvae decreased gradually, but no significant difference was observed between treatments STS and GTS. The total sugar content in the larvae in treatment STS increased after an initial decrease, but that in treatment GTS continued to decline. Four species of low molecular carbohydrates, i. e. , trehalose, glucose, glycerol and fructose were detected in the larvae. In treatment STS, the contents of glycose, glycerol and fructose in the larvae decreased after an initial increase, while the trehalose content was in adverse. In treatment GTS, the trehalose content decreased first and increased then, the glucose and glycerol were in adverse, but the fructose content had little change. In the range from 14 to -14 degrees C, the SOD and POD activities in the larvae in treatment STS were significantly lower than those in treatment GTS, but the CAT activity was in adverse. The changes of these indices reflected the physiological responses of C. suppressalis diapause larvae to different temperature stress.

  19. Active walker model for the formation of human and animal trail systems

    NASA Astrophysics Data System (ADS)

    Helbing, Dirk; Schweitzer, Frank; Keltsch, Joachim; Molnár, Péter

    1997-09-01

    Active walker models have recently proved their great value for describing the formation of clusters, periodic patterns, and spiral waves as well as the development of rivers, dielectric breakdown patterns, and many other structures. It is shown that they also allow one to simulate the formation of trail systems by pedestrians and ants, yielding a better understanding of human and animal behavior. A comparison with empirical material shows a good agreement between model and reality. Our trail formation model includes an equation of motion, an equation for environmental changes, and an orientation relation. It contains some model functions, which are specified according to the characteristics of the considered animals or pedestrians. Not only the kind of environmental changes differs: Whereas pedestrians leave footprints on the ground, ants produce chemical markings for their orientation. Nevertheless, it is more important that pedestrians steer towards a certain destination, while ants usually find their food sources by chance, i.e., they reach their destination in a stochastic way. As a consequence, the typical structure of the evolving trail systems depends on the respective species. Some ant species produce a dendritic trail system, whereas pedestrians generate a minimal detour system. The trail formation model can be used as a tool for the optimization of pedestrian facilities: It allows urban planners to design convenient way systems which actually meet the route choice habits of pedestrians.

  20. Description and field performance of the Walker Branch throughfall displacement experiment: 1993--1996

    SciTech Connect

    Hanson, P.J.; Todd, D.E.; Huston, M.A.; Joslin, J.D.; Croker, J.L.; Auge, R.M.

    1998-04-01

    The authors are conducting a large-scale manipulative field experiment in an upland oak forest on the Walker Branch Watershed in eastern Tennessee to identify important ecosystem responses that might result from future precipitation changes. The manipulation of soil water content is being implemented by a gravity-driven transfer of throughfall from one 6400-m{sup 2} treatment plot to another. Throughfall is intercepted in {approx}1850 subcanopy troughs suspended above the forest floor of the dry plot and transferred by gravity flow across an ambient plot for subsequent distribution onto the wet treatment plot. Soil water content is being monitored at two depths with time domain reflectometers at 310 sampling locations across the site. The experimental system is able to produce statistically significant differences in soil water content in years having both dry and wet conditions. Maximum soil water content differentials between wet and dry plots in the 0- to 0.35-m horizon were 8 to 10% during summers with abundant precipitation and 3 to 5% during drought periods. Treatment impacts on soil water potential were restricted to the surface soil layer. Comparisons of pre- and post-installation soil and litter temperature measurements showed the ability of the experimental design to produce changes in soil water content and water potential without creating large artifacts in the forest understory environment.

  1. Mutations in PIEZO2 Cause Gordon Syndrome, Marden-Walker Syndrome, and Distal Arthrogryposis Type 5

    PubMed Central

    McMillin, Margaret J.; Beck, Anita E.; Chong, Jessica X.; Shively, Kathryn M.; Buckingham, Kati J.; Gildersleeve, Heidi I.S.; Aracena, Mariana I.; Aylsworth, Arthur S.; Bitoun, Pierre; Carey, John C.; Clericuzio, Carol L.; Crow, Yanick J.; Curry, Cynthia J.; Devriendt, Koenraad; Everman, David B.; Fryer, Alan; Gibson, Kate; Giovannucci Uzielli, Maria Luisa; Graham, John M.; Hall, Judith G.; Hecht, Jacqueline T.; Heidenreich, Randall A.; Hurst, Jane A.; Irani, Sarosh; Krapels, Ingrid P.C.; Leroy, Jules G.; Mowat, David; Plant, Gordon T.; Robertson, Stephen P.; Schorry, Elizabeth K.; Scott, Richard H.; Seaver, Laurie H.; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, Sehime G.; Weaver, David D.; Whiteford, Margo; Williams, Marc S.; Tabor, Holly K.; Smith, Joshua D.; Shendure, Jay; Nickerson, Deborah A.; Bamshad, Michael J.

    2014-01-01

    Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher’s exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition. PMID:24726473

  2. Physical basis for the symmetries in the Friedmann-Robertson-Walker metric

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    2016-08-01

    Modern cosmological theory is based on the Friedmann-Robertson-Walker (FRW) metric. Often written in terms of co-moving coordinates, this well-known solution to Einstein's equations owes its elegant and highly practical formulation to the cosmological principle and Weyl's postulate, upon which it is founded. However, there is physics behind such symmetries, and not all of it has yet been recognized. In this paper, we derive the FRW metric coefficients from the general form of the spherically symmetric line element and demonstrate that, because the co-moving frame also happens to be in free fall, the symmetries in FRW are valid only for a medium with zero active mass. In other words, the spacetime of a perfect fluid in cosmology may be correctly written as FRW only when its equation of state is ρ+3 p = 0, in terms of the total pressure p and total energy density ρ. There is now compelling observational support for this conclusion, including the Alcock-Paczýnski test, which shows that only an FRW cosmology with zero active mass is consistent with the latest model-independent baryon acoustic oscillation data.

  3. The Walker 256 Breast Cancer Cell- Induced Bone Pain Model in Rats

    PubMed Central

    Shenoy, Priyank A.; Kuo, Andy; Vetter, Irina; Smith, Maree T.

    2016-01-01

    The majority of patients with terminal breast cancer show signs of bone metastasis, the most common cause of pain in cancer. Clinically available drug treatment options for the relief of cancer-associated bone pain are limited due to either inadequate pain relief and/or dose-limiting side-effects. One of the major hurdles in understanding the mechanism by which breast cancer causes pain after metastasis to the bones is the lack of suitable preclinical models. Until the late twentieth century, all animal models of cancer induced bone pain involved systemic injection of cancer cells into animals, which caused severe deterioration of animal health due to widespread metastasis. In this mini-review we have discussed details of a recently developed and highly efficient preclinical model of breast cancer induced bone pain: Walker 256 cancer cell- induced bone pain in rats. The model involves direct localized injection of cancer cells into a single tibia in rats, which avoids widespread metastasis of cancer cells and hence animals maintain good health throughout the experimental period. This model closely mimics the human pathophysiology of breast cancer induced bone pain and has great potential to aid in the process of drug discovery for treating this intractable pain condition.

  4. Ascending auditory interneurons in the cricket Teleogryllus commodus (Walker): comparative physiology and direct connections with afferents.

    PubMed

    Hennig, R M

    1988-05-01

    Ascending auditory interneurons of the cricket, Teleogryllus commodus (Walker), were investigated using simultaneous intracellular and extracellular recording in order to identify units which had previously been characterized only by extracellular recording. The morphology and physiology of the large adapting unit (LAU: Fig. 1) and of the small tonic unit (STU: Fig. 2) of Teleogryllus correspond well to those of the ascending neuron 2 (AN2) and the ascending neuron 1 (AN1) of Gryllus (Figs. 1, 2), respectively. A summary of the ascending auditory interneurons described by various authors in 5 species of crickets is presented in order to establish common identities. Physiological evidence for direct connections between auditory afferents and the ascending auditory interneurons AN1 (STU) and AN2 (LAU) is presented. Simultaneous intracellular recordings from receptors and interneurons in response to sound as well as the activity of auditory interneurons upon electrical stimulation of the tympanal nerve reveal short and constant latencies of receptor-evoked synaptic activity in AN1 (STU) and AN2 (LAU).

  5. Innovative use of an automated horse walker when breaking in young horses.

    PubMed

    Murphy, Jack

    2008-01-01

    There is an inherent element of risk associated with "backing" and riding the previously unbroken horse. If training proceeds too quickly, conflict behaviors may result from the simultaneous application of too many cues. Automated horse walkers (AHW) facilitate the exercising of several horses concurrently at walk or trot for warm-up, cool-down, fitness programs, and rehabilitation purposes. The objective of this study was to investigate if backing the horse within the AHW was an appropriate training method. Ten horses (3-year-olds) took part in this study. They began training within the AHW with a simple bridle and protective boots. A handler subsequently long-reined the horses within the AHW when they wore rollers, side reins, and a saddle. When considered appropriate, the handler went from jumping beside the horse to lying over the saddle to sitting astride the horse within the AHW. The horses habituated to this innovative approach quickly without evidence of conflict behavior. The handler rode the horses from the AHW after approximately 4 riding episodes of this innovative training system.

  6. Corrected entropy of Friedmann-Robertson-Walker universe in tunneling method

    SciTech Connect

    Zhu, Tao; Ren, Ji-Rong; Li, Ming-Fan E-mail: renjr@lzu.edu.cn

    2009-08-01

    In this paper, we study the thermodynamic quantities of Friedmann-Robertson-Walker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by Banerjee and Majhi [25]. For this we first calculate the corrected Hawking-like temperature on apparent horizon by considering both scalar particle and fermion tunneling. With this corrected Hawking-like temperature, the explicit expressions of the corrected entropy of apparent horizon for various gravity theories including Einstein gravity, Gauss-Bonnet gravity, Lovelock gravity, f(R) gravity and scalar-tensor gravity, are computed. Our results show that the corrected entropy formula for different gravity theories can be written into a general expression (4.39) of a same form. It is also shown that this expression is also valid for black holes. This might imply that the expression for the corrected entropy derived from tunneling method is independent of gravity theory, spacetime and dimension of the spacetime. Moreover, it is concluded that the basic thermodynamical property that the corrected entropy on apparent horizon is a state function is satisfied by the FRW universe.

  7. Mutations in PIEZO2 cause Gordon syndrome, Marden-Walker syndrome, and distal arthrogryposis type 5.

    PubMed

    McMillin, Margaret J; Beck, Anita E; Chong, Jessica X; Shively, Kathryn M; Buckingham, Kati J; Gildersleeve, Heidi I S; Aracena, Mariana I; Aylsworth, Arthur S; Bitoun, Pierre; Carey, John C; Clericuzio, Carol L; Crow, Yanick J; Curry, Cynthia J; Devriendt, Koenraad; Everman, David B; Fryer, Alan; Gibson, Kate; Giovannucci Uzielli, Maria Luisa; Graham, John M; Hall, Judith G; Hecht, Jacqueline T; Heidenreich, Randall A; Hurst, Jane A; Irani, Sarosh; Krapels, Ingrid P C; Leroy, Jules G; Mowat, David; Plant, Gordon T; Robertson, Stephen P; Schorry, Elizabeth K; Scott, Richard H; Seaver, Laurie H; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, Sehime G; Weaver, David D; Whiteford, Margo; Williams, Marc S; Tabor, Holly K; Smith, Joshua D; Shendure, Jay; Nickerson, Deborah A; Bamshad, Michael J

    2014-05-01

    Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher's exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition. PMID:24726473

  8. South China Sea hydrological changes and Pacific Walker Circulation variations over the last millennium.

    PubMed

    Yan, Hong; Sun, Liguang; Oppo, Delia W; Wang, Yuhong; Liu, Zhonghui; Xie, Zhouqing; Liu, Xiaodong; Cheng, Wenhan

    2011-01-01

    The relative importance of north-south migrations of the intertropical convergence zone (ITCZ) versus El Niño-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that north-south ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability profoundly influenced tropical Pacific hydrology. We present hydrological reconstructions from Cattle Pond, Dongdao Island of the South China Sea, where multi-decadal rainfall and downcore grain size variations are correlated to the Southern Oscillation Index during the instrumental era. Our downcore grain size reconstructions indicate that this site received less precipitation during relatively warm periods, AD 1000-1400 and AD 1850-2000, compared with the cool period (AD 1400-1850). Including our new reconstructions in a synthesis of tropical Pacific records results in a spatial pattern of hydrologic variability that implicates the PWC.

  9. Mercury in the Walker River Basin, Nevada and California--sources, distribution, and potential effects on the ecosystem

    USGS Publications Warehouse

    Seiler, Ralph L.; Lico, Michael S.; Wiemeyer Evers, David C.

    2004-01-01

    Mercury is one of the most serious contaminants of water, sediment, and biota in Nevada because of its use during 19th century mining activities to recover gold and silver from ores. In 1998, mercury problems were discovered in the Walker River Basin of California and Nevada when blood drawn from three common loons from Walker Lake was analyzed and found to have severely elevated mercury levels. From 1999 to 2001, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collected water, sediment, and biological samples to determine mercury sources, distribution, and potential effects on the Walker River Basin ecosystem. Total-mercury concentrations ranged from 0.62 to 57.11 ng/L in streams from the Walker River system and ranged from 1.02 to 26.8 ng/L in lakes and reservoirs. Total-mercury concentrations in streambed sediment ranged from 1 to 13,600 ng/g, and methylmercury concentrations ranged from 0.07 to 32.1 ng/g. The sediment-effects threshold for mercury for fresh-water invertebrates is 200 ng/g, which was exceeded at nine stream sites in the Walker River Basin. The highest mercury concentrations were in streams with historic mines and milling operations in the watershed. The highest mercury concentration in sediment, 13,600 ng/g, was found in Bodie Creek near Bodie, Calif., a site of extensive gold mining and milling activities during the 19th century. Sediment cores taken from Walker Lake show total-mercury concentrations exceeding 1,000 ng/g at depths greater than 15 cm below lake bottom. The presence of 137Cs above 8 cm in one core indicates that the upper 8 cm was deposited sometime after 1963. The mercury peak at 46 cm in that core, 2,660 ng/g, likely represents the peak of mining and gold extraction in the Bodie and Aurora mining districts between 1870 and 1880. Mercury concentrations in aquatic invertebrates at all sites downstream from mining activities in the Rough Creek watershed, which drains the Bodie and Aurora mining districts, were

  10. Pilot Joe Walker in Lunar Landing Research Vehicle (LLRV) on ramp

    NASA Technical Reports Server (NTRS)

    1964-01-01

    In this 1964 NASA Flight Research Center photograph, NASA Pilot Joe Walker is setting in the pilot's platform of the the Lunar Landing Research Vehicle (LLRV) number 1. This photograph provides a good view of the pilot setting in front of the primary instrumentation panel. When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon's surface. Three concepts surfaced: an electronic simulator, a tethered device, and the ambitious Dryden contribution, a free-flying vehicle. All three became serious projects, but eventually the NASA Flight Research Center's (FRC) Landing Research Vehicle (LLRV) became the most significant one. Hubert M. Drake is credited with originating the idea, while Donald Bellman and Gene Matranga were senior engineers on the project, with Bellman, the project manager. Simultaneously, and independently, Bell Aerosystems Company, Buffalo, N.Y., a company with experience in vertical takeoff and landing (VTOL) aircraft, had conceived a similar free-flying simulator and proposed their concept to NASA headquarters. NASA Headquarters put FRC and Bell together to collaborate. The challenge was; to allow a pilot to make a vertical landing on earth in a simulated moon environment, one sixth of the earth's gravity and with totally transparent aerodynamic forces in a 'free flight' vehicle with no tether forces acting on it. Built of tubular aluminum like a giant four-legged bedstead, the vehicle was to simulate a lunar landing profile from around 1500 feet to the moon's surface. To do this, the LLRV had a General Electric CF-700-2V turbofan engine mounted vertically in gimbals, with 4200 pounds of thrust. The engine, using JP-4 fuel, got the vehicle up to the test altitude and was then throttled back to support five-sixths of the vehicle's weight, simulating the reduced gravity of the moon. Two hydrogen-peroxide lift rockets with thrust that could be varied from 100 to 500 pounds handled the LLRV's rate of

  11. Geophysical characterization of transtensional fault systems in the Eastern California Shear Zone-Walker Lane Belt

    NASA Astrophysics Data System (ADS)

    McGuire, M.; Keranen, K. M.; Stockli, D. F.; Feldman, J. D.; Keller, G. R.

    2011-12-01

    The Eastern California Shear Zone (ECSZ) and Walker Lane belt (WL) accommodate ~25% of plate motion between the North American and Pacific plates. Faults within the Mina deflection link the ECSZ and the WL, transferring strain from the Owens Valley and Death Valley-Fish Lake Valley fault systems to the transcurrent faults of the central Walker Lane. During the mid to late Miocene the majority of strain between these systems was transferred through the Silver Peak-Lone Mountain (SPLM) extensional complex via a shallowly dipping detachment. Strain transfer has since primarily migrated north to the Mina Deflection; however, high-angle faults bounding sedimentary basins and discrepancies between geodetic and geologic models indicate that the SPLM complex may still actively transfer a portion of the strain from the ECSZ to the WL on a younger set of faults. Establishing the pattern and amount of active strain transfer within the SPLM region is required for a full accounting of strain accommodation, and provides insight into strain partitioning at the basin scale within a broader transtensional zone. To map the active structures in and near Clayton Valley, within the SPLM region, we collected seismic reflection and refraction profiles and a dense grid of gravity readings that were merged with existing gravity data. The primary goals were to determine the geometry of the high-angle fault system, the amount and sense of offset along each fault set, connectivity of the faults, and the relationship of these faults to the Miocene detachment. Seismic reflection profiles imaged the high-angle basin-bounding normal faults and the detachment in both the footwall and hanging wall. The extensional basin is ~1 km deep, with a steep southeastern boundary, a gentle slope to the northwest, and a sharp boundary on the northwest side, suggestive of another fault system. Two subparallel dip-slip faults bound the southeast (deeper) basin margin with a large lateral velocity change (from ~2

  12. Mass balance of trace elements in Walker branch watershed: relation to coal-fired steam plants.

    PubMed Central

    Lindberg, S E; Andren, A W; Raridon, R J; Fulkerson, W

    1975-01-01

    A mass balance study of trace element flows at the TVA Allen Steam Plant at Memphis showed that most of the released Hg, some Se, and probably most Cl and Br are discharged to the atmosphere as gases. The elements As, Cd, Cu, Ga, Mo, Pb, Sb, Se, and Zn were concentrated in fly ash compared to slag and were more concentrated in the ash discharged through the stack than in that collected by the precipitator, while Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mg, Mn, Rb, Sm, Sr, Ta, Th, and Ti showed little preferential partitioning between the slag and the collected or discharged fly ash. The elements Cr, Cs, Na, Ni, U, and V exhibited behavior intermediate between the latter two groups. This information about stack emissions of trace elements from the Allen Plant was used to estimate the likely range of air concentrations and input (dry and wet deposition) to the Walker Branch Watershed. The watershed, which is on the ERDA reservation at Oak Ridge, is within 20 km of three coal-fired steam plants, two in the TVA system and one belonging to ERDA. The estimated input values are compared to measurements of Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in wet precipitation falling on the watershed during 1973 and 1974. Dry deposition of these elements could not be measured directly but estimates indicated that this could be of the same order of magnitude as the rainwater input. A six-month mass balance indicated that the watershed efficiently retains Pb (97-98% of the atmospheric input,) Cu (82-84%), while Cr (69%), Mn (57%), Zn (73%), and Hg (69%) are less well retained. Images FIGURE 3. PMID:1227866

  13. Reduced renal sodium excretion in Walker-256 tumor-bearing rats.

    PubMed

    Rettori, O; Vieira-Matos, A N; Gontijo, J A

    1996-01-01

    Subcutaneous inoculation of Walker-256 tumor is followed by an asymptomatic period which is widely variable in duration, after which, paraneoplastic effects appear suddenly in the form of progressive and rapidly changing homeostatic alterations. Multifocal inoculation of tumor cells in each animal, was carried out with data averaging in each (sub-clinical [SubC], moderate [mCP] and grave [gCP] clinical phases and compared to foodrestricted (FR) rats. Results showed a significant and early decrease in urinary sodium excretion during mCP when compared to SubC and FR. The renal sites involved were studied in awake unrestrained animals by measure of sodium, creatinine and lithium clearance. Results indicated an initial increase of both absolute proximal (mCP: 21.4 +/- 1.7 vs FR: 16.0 +/- 1.1 mmol@min/100 g.b.w., p < 0.05) and postproximal (mCP: 11.1 +/- 0.4 vs FR: 6.6 +/- 0.4 mmol/min/100 g b.w., p < 0.001) Na+ reabsorption, which were partially compensated by a rise in glomerular filtration rate (mCP: 213 +/- 11.4 vs FR: 162+ 10.2pl/min/100 g b.w., p < 0.01) and by fell of fractional proximal Na+ reabsorption (mCP: 62.8 +/- 2.2 vs FR: 70.1 +/- 1.7%, p < 0.05), despite this a significant Na+ and fluid retention was observed. Additionally, this study shows that terminal phase of the illness (gCP) culminated with a marked decrease in the creatinine clearance suggesting a significant fall of the renal function.

  14. Cenozoic strike-slip faults in the northern Wassuk Range, Walker Lane

    SciTech Connect

    Dilles, J.H. . Geosciences Dept.)

    1993-04-01

    The N. Wassuk Ra. yields estimates of right-lateral Cenozoic strain in a portion of the northwest-trending Walker Lane, which has a total estimated right-lateral strain of 48--60 km (Ekren et al., 1984). The net right-lateral strain is < 10 km within an east-west 50 km-long segment extending from the N. Wassuk Ra. west to the Pine Nut Mts on the basis of continuous Jurassic plutonic units: Yerington batholith and quartz monzodiorite porphyry dikes. One of two dikes in the N. Wassuk Ra. may correlate easterly to Gillis Ra., suggesting [approximately]10 or 25 km right-lateral offset (Diles and R. Hardyman, unpub). In the N. Wassuk Ra. there are several ages of northwesterly striking faults. The oldest are [approximately]N45[degree]W striking, steeply dipping faults including the White Mt. and Wassuk Spur faults that step left to the northwest. Associated moderately dipping faults have tilted Oligocene tuffs to the W or SW to the SW of the fault zone, and both E and W on the NW; based on offset of the Jurassic porphyry dike and slickensides, these faults were dominantly oblique-slip normal faults with WNW-ESE slip. No lateral offsets can be directly measured across the steeply dipping faults; however, they juxtapose different Mesozoic metamorphic rocks and different thicknesses of Oligocene ignimbrites, suggesting significant lateral offset. Bingler's (1978) proposal that the White Mt. fault had left-laterally offset the White Mt. granite (WMG) from granite of Black Mountain (BMG) is unreasonable because the BMG intrudes the Wassuk Range diorite and contain biotite aplites, whereas the WMG intrudes metavolcanic rocks and contains tourmaline-muscovite aplites.

  15. Bioactivity-guided isolation of antiplasmodial constituents from Conyza sumatrensis (Retz.) E.H. Walker.

    PubMed

    Boniface, Pone Kamdem; Verma, Surjeet; Shukla, Aparna; Cheema, Harveer Singh; Srivastava, Santosh Kumar; Khan, Feroz; Darokar, Mahendra Pandurang; Pal, Anirban

    2015-02-01

    Conyza sumatrensis (Retz.) E.H. Walker (Cs) leaves are used for traditional treatment of malaria in Cameroon. However, the antimalarial activity of the leaf constituents of this plant is still unexplored. The aim of our investigation was to evaluate the antiplasmodial activity of some bioactive constituents from Cs leaves. Compounds were isolated from Cs leaves and structurally elucidated using extensive spectroscopic analysis. The in vitro antiplasmodial activity of the extracts and pure compounds were evaluated on chloroquine-sensitive strain (NF54) of Plasmodium falciparum. The in vivo assay was done by administering seven doses of extracts in mice infected with Plasmodium berghei K173 through oral route. Cytotoxicity of pure compounds on murine macrophage cells was performed through [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] (MTT) test. Hemolysis and lactate dehydrogenase assays were also carried out using standard procedures. The in silico prediction of bioactive constituents was performed through Autodock Vina. Polarity-based extracts from Cs were found to be active against P. falciparum (NF54) and P. berghei (K173) in vitro and in vivo respectively. Further, bioactivity-guided isolation of n-hexane fraction yielded three compounds, (1), (2) and (3) with IC50 of 34, 17.9 and 18μg/ml, respectively, while the ethyl acetate fraction afforded the fourth compound with an IC50 of 25μg/ml, indicating anti-malarial potential of Cs through PfLDH interaction without compromising normal cell growth. This study reports for the first time, the antiplasmodial activity of bioactive constituents from Cs and confirms its traditional use.

  16. Evidence for Interannual to Decadal Variations in Hadley and Walker Circulations and Links to Water and Energy Fluxes

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin; Bosilovich, Michael; Miller, Timothy

    2007-01-01

    Mass and energy transports associated with the Hadley and Walker circulations are important components of the earth s climate system and are strongly linked to hydrologic processes. Interannual to decadal variation in these flows likely signify a combination of natural climate noise as well as a response to anthropgenic forcing. There remains considerable uncertainty in quantifying variations in these flows. Evidence in the surface pressure record supports a weakening of the Walker circulation over the Pacific in recent decades. Conversely the NCEP / NCAR and ERA 40 reanalyses indicate that the Hadley circulation has increased in strength over the last two decades, though these analyses depict significantly different mass circulation changes. Interestingly, the NCEP - II / DOE reanalysis contains essentially no Hadley circulation changes. Most climate model integrations anticipate a weakening of both tropical circulations associated with stronger static stability. Clearly there is much uncertainty not only with the mass transports, but also how they are linked to water and energy balance of the planet through variations in turbulent heat and radiative fluxes and horizontal exports / imports of energy. Here we examine heat and water budget variations from a number of reanalysis products and focus on the linear and nonlinear response of ENSO warm and cold events as opportunities to study budget variations over the past 15-20 years. Our analysis addresses such questions as To what extent do Hadley and Walker Cell variations compensate each other on mass and energy transport? Do static stability adjustments appear to constrain fractional precipitation response vs. fractional water vapor response? We appeal to constraints offered by GPCP precipitation, SSWI ocean evaporation estimates, and ISCCP-FD radiative fluxes, and other satellite data sets to interpret and confirm reanalysis-based diagnostics. Using our findings we also attempt to place in context the recent

  17. Effectiveness of Removable Walker Cast Versus Nonremovable Fiberglass Off-Bearing Cast in the Healing of Diabetic Plantar Foot Ulcer

    PubMed Central

    Faglia, Ezio; Caravaggi, Carlo; Clerici, Giacomo; Sganzaroli, Adriana; Curci, Vincenzo; Vailati, Wanda; Simonetti, Daniele; Sommalvico, Francesco

    2010-01-01

    OBJECTIVE To evaluate the efficacy of a removable cast walker compared with that of a nonremovable fiberglass off-bearing cast in the treatment of diabetic plantar foot ulcer. RESEARCH DESIGN AND METHODS Forty-five adult diabetic patients with nonischemic, noninfected neuropathic plantar ulcer were randomly assigned for treatment with a nonremovable fiberglass off-bearing cast (total contact cast [TCC] group) or walker cast (Stabil-D group). Treatment duration was 90 days. Percent reduction in ulcer surface area and total healing rates were evaluated after treatment. RESULTS A total of 48 patients were screened; however, 2 patients in the TCC group and 1 patient in the Stabil-D group did not complete the study and were considered dropouts. There were no significant differences in demographic and clinic characteristics of the 45 patients completing the study. Ulcer surface decreased from 1.41 to 0.21 cm2 (P < 0.001) in the TCC group and from 2.18 to 0.45 cm2 (P < 0.001) in the Stabil-D group, with no significant differences between groups (P = 0.722). Seventeen patients (73.9%) in the TCC group and 16 patients (72.7%) in the Stabil-D group achieved healing (P = 0.794). Average healing time was 35.3 ± 3.1 and 39.7 ± 4.2 days in the TCC and Stabil-D group, respectively (P = 0.708). CONCLUSIONS The Stabil-D cast walker, although removable, was equivalent in efficacy to the TCC in terms of ulcer size reduction and total healing rate. The easier use of Stabil-D may help increase the use of off-loading devices in the management of plantar neuropathic diabetic foot ulcers. PMID:20357377

  18. A radiative-convective equilibrium perspective of the weakening of tropical Walker circulation in response to global warming

    NASA Astrophysics Data System (ADS)

    Huang, X.; Chuang, H.; Dessler, A. E.; Chen, X.; Minschwaner, K. R.; Ming, Y.; Ramaswamy, V.

    2012-12-01

    Both observational analysis and GCM simulations indicate that the tropical Walker circulation is becoming weaker and may continue to weaken as a consequence of climate change. Here we use a conceptual radiative-convective-equilibrium (RCE) framework to interpret the weakening of the Walker circulation as simulated by the GFDL coupled-GCM. Based on the modeled lapse rate and clear-sky cooling rate profiles, the RCE framework can directly compute the change of vertical velocity in the descending branch of the Walker circulation, which agrees with the counterpart simulated by the GFDL model. Our results show that the vertical structure of clear-sky radiative cooling rate (QR) will change in response to the water vapor and lapse rate feedbacks as the globe warms. We explain why the change of QR is positive in the upper most part of the troposphere (<300 hPa) and is negative for the rest of the troposphere. As a result, both the change of clear-sky cooling rate and the change of tropospheric lapse rate contribute to the weakening of circulation. The vertical velocity changes due to the two factors are comparable to each other from the top of planetary boundary layer to 600hPa. From 600hPa to 300hPa, lapse rate changes are the dominant cause of the weakening circulation. Above 300hPa, the change due to QR is opposite to the change due to lapse rate, which forces a slight increase in vertical velocity that is seen in the model simulation.

  19. Neuropsychological Function in a Case of Dandy-Walker Variant in a 68-Year-Old Veteran.

    PubMed

    Gross, Patricia L; Kays, Jill L; Shura, Robert D

    2016-01-01

    Dandy-Walker syndrome (DWS) is a congenital brain malformation that is characterized by partial or complete agenesis of the cerebellar vermis and cystic dilatation of the 4th ventricle that shifts ventrolaterally to displace the cerebellar hemispheres. This case is a 68-year-old male veteran with complaints of new-onset cognitive disorder who was found to have previously unsuspected DWS on head computed tomography. This is one of the first case studies to present complete neuropsychological test results in a veteran with DWS. Despite the level of abnormality on imaging, the veteran functioned well until onset of mild cognitive impairments in late adulthood.

  20. Comment on 'Quantization of Friedmann-Robertson-Walker spacetimes in the presence of a negative cosmological constant and radiation'

    SciTech Connect

    Amore, Paolo; Aranda, Alfredo; Cervantes, Mayra; Diaz-Cruz, J. L.; Fernandez, Francisco M.

    2007-03-15

    The quantization of the Friedmann-Robertson-Walker spacetime in the presence of a negative cosmological constant was used in a recent paper to conclude that there are solutions that avoid singularities (big bang-big crunch) at the quantum level. We show that a proper study of their model does not indicate that it prevents the occurrence of singularities at the quantum level, in fact the quantum probability of such event is larger than the classical one. Our numerical simulations based on the powerful variational sinc collocation method (VSCM) also show that the precision of the results of that paper is much lower than the 20 significant digits reported by the authors.

  1. On the initial value problem for the wave equation in Friedmann-Robertson-Walker space-times.

    PubMed

    Abbasi, Bilal; Craig, Walter

    2014-09-01

    The propagator W(t0,t1)(g,h) for the wave equation in a given space-time takes initial data (g(x),h(x)) on a Cauchy surface {(t,x) : t=t0} and evaluates the solution (u(t1,x),∂ tu(t1,x)) at other times t1. The Friedmann-Robertson-Walker space-times are defined for t0,t1>0, whereas for t0→0, there is a metric singularity. There is a spherical means representation for the general solution of the wave equation with the Friedmann-Robertson-Walker background metric in the three spatial dimensional cases of curvature K=0 and K=-1 given by S. Klainerman and P. Sarnak. We derive from the expression of their representation three results about the wave propagator for the Cauchy problem in these space-times. First, we give an elementary proof of the sharp rate of time decay of solutions with compactly supported data. Second, we observe that the sharp Huygens principle is not satisfied by solutions, unlike in the case of three-dimensional Minkowski space-time (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 00 emanating from the space-time singularity at t=0. Under reflection t→-t, the Friedmann-Robertson-Walker metric gives a space-time metric for t<0 with a singular future at t=0, and the same solution formulae hold. We thus have constructed solutions u(t,x) of the wave equation in Friedmann-Robertson-Walker space-times which exist for all [Formula: see text] and [Formula: see text], where in conformally regularized coordinates, these solutions are continuous through the singularity t=0 of space-time, taking on specified data u(0,⋅)=g(⋅) at the singular time.

  2. On the initial value problem for the wave equation in Friedmann–Robertson–Walker space–times

    PubMed Central

    Abbasi, Bilal; Craig, Walter

    2014-01-01

    The propagator W(t0,t1)(g,h) for the wave equation in a given space–time takes initial data (g(x),h(x)) on a Cauchy surface {(t,x) : t=t0} and evaluates the solution (u(t1,x),∂tu(t1,x)) at other times t1. The Friedmann–Robertson–Walker space–times are defined for t0,t1>0, whereas for t0→0, there is a metric singularity. There is a spherical means representation for the general solution of the wave equation with the Friedmann–Robertson–Walker background metric in the three spatial dimensional cases of curvature K=0 and K=−1 given by S. Klainerman and P. Sarnak. We derive from the expression of their representation three results about the wave propagator for the Cauchy problem in these space–times. First, we give an elementary proof of the sharp rate of time decay of solutions with compactly supported data. Second, we observe that the sharp Huygens principle is not satisfied by solutions, unlike in the case of three-dimensional Minkowski space–time (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 00 emanating from the space–time singularity at t=0. Under reflection t→−t, the Friedmann–Robertson–Walker metric gives a space–time metric for t<0 with a singular future at t=0, and the same solution formulae hold. We thus have constructed solutions u(t,x) of the wave equation in Friedmann–Robertson–Walker space–times which exist for all −∞

  3. Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination.

    PubMed

    Giblin, John T; Mertens, James B; Starkman, Glenn D

    2016-06-24

    While the use of numerical general relativity for modeling astrophysical phenomena and compact objects is commonplace, the application to cosmological scenarios is only just beginning. Here, we examine the expansion of a spacetime using the Baumgarte-Shapiro-Shibata-Nakamura formalism of numerical relativity in synchronous gauge. This work represents the first numerical cosmological study that is fully relativistic, nonlinear, and without symmetry. The universe that emerges exhibits an average Friedmann-Lemaître-Robertson-Walker (FLRW) behavior; however, this universe also exhibits locally inhomogeneous expansion beyond that expected in linear perturbation theory around a FLRW background. PMID:27391710

  4. Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination

    NASA Astrophysics Data System (ADS)

    Giblin, John T.; Mertens, James B.; Starkman, Glenn D.

    2016-06-01

    While the use of numerical general relativity for modeling astrophysical phenomena and compact objects is commonplace, the application to cosmological scenarios is only just beginning. Here, we examine the expansion of a spacetime using the Baumgarte-Shapiro-Shibata-Nakamura formalism of numerical relativity in synchronous gauge. This work represents the first numerical cosmological study that is fully relativistic, nonlinear, and without symmetry. The universe that emerges exhibits an average Friedmann-Lemaître-Robertson-Walker (FLRW) behavior; however, this universe also exhibits locally inhomogeneous expansion beyond that expected in linear perturbation theory around a FLRW background.

  5. Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination.

    PubMed

    Giblin, John T; Mertens, James B; Starkman, Glenn D

    2016-06-24

    While the use of numerical general relativity for modeling astrophysical phenomena and compact objects is commonplace, the application to cosmological scenarios is only just beginning. Here, we examine the expansion of a spacetime using the Baumgarte-Shapiro-Shibata-Nakamura formalism of numerical relativity in synchronous gauge. This work represents the first numerical cosmological study that is fully relativistic, nonlinear, and without symmetry. The universe that emerges exhibits an average Friedmann-Lemaître-Robertson-Walker (FLRW) behavior; however, this universe also exhibits locally inhomogeneous expansion beyond that expected in linear perturbation theory around a FLRW background.

  6. On the initial value problem for the wave equation in Friedmann-Robertson-Walker space-times.

    PubMed

    Abbasi, Bilal; Craig, Walter

    2014-09-01

    The propagator W(t 0,t 1)(g,h) for the wave equation in a given space-time takes initial data (g(x),h(x)) on a Cauchy surface {(t,x) : t=t 0} and evaluates the solution (u(t 1,x),∂ t u(t 1,x)) at other times t 1. The Friedmann-Robertson-Walker space-times are defined for t 0,t 1>0, whereas for t 0→0, there is a metric singularity. There is a spherical means representation for the general solution of the wave equation with the Friedmann-Robertson-Walker background metric in the three spatial dimensional cases of curvature K=0 and K=-1 given by S. Klainerman and P. Sarnak. We derive from the expression of their representation three results about the wave propagator for the Cauchy problem in these space-times. First, we give an elementary proof of the sharp rate of time decay of solutions with compactly supported data. Second, we observe that the sharp Huygens principle is not satisfied by solutions, unlike in the case of three-dimensional Minkowski space-time (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 00 emanating from the space-time singularity at t=0. Under reflection t→-t, the Friedmann-Robertson-Walker metric gives a space-time metric for t<0 with a singular future at t=0, and the same solution formulae hold. We thus have constructed solutions u(t,x) of the wave equation in Friedmann-Robertson-Walker space-times which exist for all [Formula: see text] and [Formula: see text], where in conformally regularized coordinates, these solutions are continuous through the singularity t=0 of space-time, taking on specified data u(0,⋅)=g(⋅) at the singular time. PMID:25197255

  7. Tectonic Tales: Changes in Central Walker Lane Strain Accommodation near Bridgeport, California; as told by the Stanislaus Group

    NASA Astrophysics Data System (ADS)

    Carlson, C. W.; Pluhar, C. J.; Glen, J. M.

    2010-12-01

    The Late-Miocene Stanislaus Group of lavas and ignimbrites were deposited across a region of diverse tectonic rates and style. Distributed east of Sonora Pass across the Walker Lane Belt into Nevada, and extending as far west as Knights Ferry along the Stanislaus River in the central Sierran foothills, the Stanislaus Group’s distinctive lithologic and paleomagnetic characteristics provide the means to reconstruct tectonic evolution in this region. Motion of the Sierra Nevada microplate is relatively straightforward while the adjacent range front fault and Walker Lane are characterized by westward propagation with time, extensive complex faulting, and vertical axis rotation of fault bounded blocks. The Stanislaus Group is composed of: 1) Table Mountain Formation, dominantly latite lavas emplaced at about ~10 Ma, 2A) Tollhouse Flat Member of the dominantly quartz latite Eureka Valley Tuff (EVT), emplaced sometime during 9.4-9.8 Ma, 2B) Latite Flow Member of EVT, 2C) By-Day Member of EVT, 9.42±0.04 Ma, 2D) Upper Member of EVT 9.43±0.02 Ma, and 3) Dardanelle Formation, composed of latite lavas, which caps the Stanislaus Group. Because of wide areal distribution across the central Walker Lane, we have used members of the Stanislaus Group to evaluate and understand regional strain in this part of the North American-Pacific plate boundary, which currently accommodates ~25% of relative dextral plate motion. Paleomagnetic analysis has yielded multiple reference remanence directions for elements of the Stanislaus Group on the “relatively stable” Sierra Nevada microplate for comparison with those same units deposited within the extensively-faulted Walker Lane to the east. Preliminary results show tectonic domains near Bridgeport, CA in the 5-10 km size range displaying eastward-increasing vertical-axis block rotation. This west-to-east increase in rotation appears to sub-parallel the Sierran frontal fault system when analyzed with data from previous studies to the

  8. Re-assessment of the renal hydrosaline dysfunction in rats bearing the Walker-256 tumor.

    PubMed

    Rettori, O; Vieira-Matos, A N; Gontijo, J A

    2000-11-01

    Sodium retention is a frequent effect of cancer in humans and animals, but the mechanism involved is not yet understood. In the Walker-256 tumor, sodium retention has been considered to be a late effect, secondary to retention in the tumor mass, and/or to adrenal hypertrophy. Normally, (in rats receiving single tumor implants), the development of different tumor systemic effects (TSE) such as anorexia, sodium and fluid retention, anemia and immune depression in rats is synchronous within each individual but random among individuals of a given group in which they appear 6-47 days, or more, after inoculation. In present study, multifocal simultaneous inoculations of tumor cells resulted in a rapid and synchronous initiation of TSE (in 3-4 days) in all rats when no local effects of metastases could mask the results. Sodium retention is a special tumor effect on Na+ balance and a very sensitive indicator of TSE initiation. The results from multifocally inoculated rats were averaged in each (sub-clinical (SubC), moderate (mCP) and grave (gCP)) clinical phase and compared to food-restricted (FR) rats. There was a significant, early decrease in urinary Na+ excretion during mCP when compared to SubC and FR. The renal sites involved were studied in awake, unrestrained animals by measuring of sodium, creatinine and lithium clearances. There was an initial increase in the absolute proximal (mCP: 21.4 +/- 1.7 vs FR: 16.0 +/- 1.1 mmol/min/100 g b.w., p < 0.05) and post-proximal (mCP: 11.1 +/- 0.4 vs FR: 6.6 +/- 0.4 mmol/min/100 g b.w., p < 0.001) Na+ reabsorption, which were partially compensated for by a rise in glomerular filtration rate (mCP: 213 +/- 11.4 vs FR: 162 +/- 10.2 microL/min/100 g b.w., p < 0.01) and by a fall in fractional proximal Na+ reabsorption (mCP: 62.8 +/- 2.2% vs FR: 70.1 +/- 1.7%, p < 0.05), despite significant Na+ and fluid retention. The terminal phase of illness (gCP) culminated with a marked decrease in creatinine clearance, suggesting a significant

  9. Epidemic modeling with discrete-space scheduled walkers: extensions and research opportunities

    PubMed Central

    2009-01-01

    Background This exploratory paper outlines an epidemic simulator built on an agent-based, data-driven model of the spread of a disease within an urban environment. An intent of the model is to provide insight into how a disease may reach a tipping point, spreading to an epidemic of uncontrollable proportions. Methods As a complement to analytical methods, simulation is arguably an effective means of gaining a better understanding of system-level disease dynamics within a population and offers greater utility in its modeling capabilities. Our investigation is based on this conjecture, supported by data-driven models that are reasonable, realistic and practical, in an attempt to demonstrate their efficacy in studying system-wide epidemic phenomena. An agent-based model (ABM) offers considerable flexibility in extending the study of the phenomena before, during and after an outbreak or catastrophe. Results An agent-based model was developed based on a paradigm of a 'discrete-space scheduled walker' (DSSW), modeling a medium-sized North American City of 650,000 discrete agents, built upon a conceptual framework of statistical reasoning (law of large numbers, statistical mechanics) as well as a correct-by-construction bias. The model addresses where, who, when and what elements, corresponding to network topography and agent characteristics, behaviours, and interactions upon that topography. The DSSW-ABM has an interface and associated scripts that allow for a variety of what-if scenarios modeling disease spread throughout the population, and for data to be collected and displayed via a web browser. Conclusion This exploratory paper also presents several research opportunities for exploiting data sources of a non-obvious and disparate nature for the purposes of epidemic modeling. There is an increasing amount and variety of data that will continue to contribute to the accuracy of agent-based models and improve their utility in modeling disease spread. The model developed

  10. Physical constraints, fundamental limits, and optimal locus of operating points for an inverted pendulum based actuated dynamic walker.

    PubMed

    Patnaik, Lalit; Umanand, Loganathan

    2015-10-26

    The inverted pendulum is a popular model for describing bipedal dynamic walking. The operating point of the walker can be specified by the combination of initial mid-stance velocity (v0) and step angle (φm) chosen for a given walk. In this paper, using basic mechanics, a framework of physical constraints that limit the choice of operating points is proposed. The constraint lines thus obtained delimit the allowable region of operation of the walker in the v0-φm plane. A given average forward velocity vx,avg can be achieved by several combinations of v0 and φm. Only one of these combinations results in the minimum mechanical power consumption and can be considered the optimum operating point for the given vx,avg. This paper proposes a method for obtaining this optimal operating point based on tangency of the power and velocity contours. Putting together all such operating points for various vx,avg, a family of optimum operating points, called the optimal locus, is obtained. For the energy loss and internal energy models chosen, the optimal locus obtained has a largely constant step angle with increasing speed but tapers off at non-dimensional speeds close to unity.

  11. Diagnosis of Van den Ende-Gupta syndrome: Approach to the Marden-Walker-like spectrum of disorders.

    PubMed

    Niederhoffer, Karen Y; Fahiminiya, Somayyeh; Eydoux, Patrice; Mawson, John; Nishimura, Gen; Jerome-Majewska, Loydie A; Patel, Millan S

    2016-09-01

    Marden-Walker syndrome is challenging to diagnose, as there is significant overlap with other multi-system congenital contracture syndromes including Beals congenital contractural arachnodactyly, D4ST1-Deficient Ehlers-Danlos syndrome (adducted thumb-clubfoot syndrome), Schwartz-Jampel syndrome, Freeman-Sheldon syndrome, Cerebro-oculo-facio-skeletal syndrome, and Van den Ende-Gupta syndrome. We discuss this differential diagnosis in the context of a boy from a consanguineous union with Van den Ende-Gupta syndrome, a diagnosis initially confused by the atypical presence of intellectual disability. SNP microarray and whole exome sequencing identified a homozygous frameshift mutation (p.L870V) in SCARF2 and predicted damaging mutations in several genes, most notably DGCR2 (p.P75L) and NCAM2 (p.S147G), both possible candidates for this child's intellectual disability. We review distinguishing features for each Marden-Walker-like syndrome and propose a clinical algorithm for diagnosis among this spectrum of disorders. © 2016 Wiley Periodicals, Inc. PMID:27375131

  12. Chronic supplementation with shark liver oil for reducing tumor growth and cachexia in walker 256 tumor-bearing rats.

    PubMed

    Iagher, Fabíola; de Brito Belo, Sérgio Ricardo; Naliwaiko, Katya; Franzói, Andressa Machado; de Brito, Gleisson Alisson Pereira; Yamazaki, Ricardo Key; Muritiba, Ana Lúcia; Muehlmann, Luis Alexandre; Steffani, Jovani Antonio; Fernandes, Luiz Cláudio

    2011-11-01

    We investigated the effect of chronic supplementation with shark liver oil (SLO), an antitumor supplement source of n-3 fatty acids and 1-O-alkylglycerols, alone and combined with coconut fat (CF), a source of saturated fatty acids, on Walker 256 tumor growth and cachexia. Male rats were supplemented daily and orally with SLO and/or CF (1 g per kg body weight) for 7 wk. After 7 wk, 50% of animals were subcutaneously inoculated with 3 × 10(7) Walker 256 tumor cells. After 14 days, the rats were killed, the tumors were removed for lipid peroxidation measurement, and blood was collected for glycemia, triacylglycerolemia, and lacticidemia evaluation. Liver samples were obtained for glycogen measurement. Unlike CF, supplementation with SLO promoted gain in body weight, reduction of tumor weight, and maintained glycemia, triacylglycerolemia, lacticidemia, and liver glycogen content to values similar to non-tumor-bearing rats. Combined supplementation of SLO with CF also showed a reversion of cachexia with gain in body mass, reduction of lacticidemia, maintaining the liver glycogen store, and reduction in tumor weight. SLO, alone or combined with CF, promoted increase of tumor lipid peroxidation. In conclusion, SLO supplemented chronically, alone or associated with CF, was able to reduce tumor growth and cachexia.

  13. Disparate requirements for the Walker A and B ATPase motifs ofhuman RAD51D in homologous recombination

    SciTech Connect

    Wiese, Claudia; Hinz, John M.; Tebbs, Robert S.; Nham, Peter B.; Urbin, Salustra S.; Collins, David W.; Thompson, Larry H.; Schild, David

    2006-04-21

    In vertebrates, homologous recombinational repair (HRR) requires RAD51 and five RAD51 paralogs (XRCC2, XRCC3, RAD51B, RAD51C, and RAD51D) that all contain conserved Walker A and B ATPase motifs. In human RAD51D we examined the requirement for these motifs in interactions with XRCC2 and RAD51C, and for survival of cells in response to DNA interstrand crosslinks. Ectopic expression of wild type human RAD51D or mutants having a non-functional A or B motif was used to test for complementation of a rad51d knockout hamster CHO cell line. Although A-motif mutants complement very efficiently, B-motif mutants do not. Consistent with these results, experiments using the yeast two- and three-hybrid systems show that the interactions between RAD51D and its XRCC2 and RAD51C partners also require a functional RAD51D B motif, but not motif A. Similarly, hamster Xrcc2 is unable to bind to the non-complementing human RAD51D B-motif mutants in co-immunoprecipitation assays. We conclude that a functional Walker B motif, but not A motif, is necessary for RAD51D's interactions with other paralogs and for efficient HRR. We present a model in which ATPase sites are formed in a bipartite manner between RAD51D and other RAD51 paralogs.

  14. Buses, Cars, Bicycles and Walkers: The Influence of the Type of Human Transport on the Flight Responses of Waterbirds

    PubMed Central

    McLeod, Emily M.; Guay, Patrick-Jean; Taysom, Alice J.; Robinson, Randall W.; Weston, Michael A.

    2013-01-01

    One way to manage disturbance to waterbirds in natural areas where humans require access is to promote the occurrence of stimuli for which birds tolerate closer approaches, and so cause fewer responses. We conducted 730 experimental approaches to 39 species of waterbird, using five stimulus types (single walker, three walkers, bicycle, car and bus) selected to mimic different human management options available for a controlled access, Ramsar-listed wetland. Across species, where differences existed (56% of 25 cases), motor vehicles always evoked shorter flight-initiation distances (FID) than humans on foot. The influence of stimulus type on FID varied across four species for which enough data were available for complete cross-stimulus analysis. All four varied FID in relation to stimuli, differing in 4 to 7 of 10 possible comparisons. Where differences occurred, the effect size was generally modest, suggesting that managing stimulus type (e.g. by requiring people to use vehicles) may have species-specific, modest benefits, at least for the waterbirds we studied. However, different stimulus types have different capacities to reduce the frequency of disturbance (i.e. by carrying more people) and vary in their capacity to travel around important habitat. PMID:24367498

  15. Buses, cars, bicycles and walkers: the influence of the type of human transport on the flight responses of waterbirds.

    PubMed

    McLeod, Emily M; Guay, Patrick-Jean; Taysom, Alice J; Robinson, Randall W; Weston, Michael A

    2013-01-01

    One way to manage disturbance to waterbirds in natural areas where humans require access is to promote the occurrence of stimuli for which birds tolerate closer approaches, and so cause fewer responses. We conducted 730 experimental approaches to 39 species of waterbird, using five stimulus types (single walker, three walkers, bicycle, car and bus) selected to mimic different human management options available for a controlled access, Ramsar-listed wetland. Across species, where differences existed (56% of 25 cases), motor vehicles always evoked shorter flight-initiation distances (FID) than humans on foot. The influence of stimulus type on FID varied across four species for which enough data were available for complete cross-stimulus analysis. All four varied FID in relation to stimuli, differing in 4 to 7 of 10 possible comparisons. Where differences occurred, the effect size was generally modest, suggesting that managing stimulus type (e.g. by requiring people to use vehicles) may have species-specific, modest benefits, at least for the waterbirds we studied. However, different stimulus types have different capacities to reduce the frequency of disturbance (i.e. by carrying more people) and vary in their capacity to travel around important habitat. PMID:24367498

  16. Redescription of Argizala brasiliensis Walker, 1869 (Orthoptera: Grylloidea: Trigonidiidae: Nemobiinae: Pteronemobiini) and consideration of its morphological proximity to other Pteronemobiini Nearctic genera.

    PubMed

    Pereira, Marcelo Ribeiro; De P Martins, Luciano; Fernandes, Maria Luiza; Zefa, Edison; Sperber, Carlos Frankl

    2015-01-01

    Although male crickets provide more informative characters for the delimitation of species and genera, many taxonomic descriptions are based only on females. This is the case for Argizala Walker, 1869 and its two valid species, A. brasiliensis Walker, 1869 and A. hebardi Rehn, 1915. We provide herein a redescription of A. brasiliensis based on a male collected in the Pampa Biome, Capão do Leão municipality, Rio Grande do Sul State, Brazil. We present photographs of epitype and male genitalia, and discuss the diagnostic features of the genus and its morphological proximity to other Pteronemobiini Nearctic genera. PMID:26249883

  17. [Effect of plant biocomposites based on Georgian tea "per se" and in combination with cisplatin on Walker carcinosarcoma W-256 and Guerin's carcinoma growth rate in rats].

    PubMed

    Zalietok, S P; Orlovs'kyĭ, O A; Hohol', S V; Samoĭlenko, O A; Hulua, L; Kvesitadze, H I

    2006-12-01

    Green tea biocomposite had effectivey hampered the growth of rat Walker W-256 carcinoma and in less extent rat Guerin's carcinoma. Black tea biocomposite had not practically influenced on Guerin's carcinoma growth. The biocomposite from green tea and extract from red vine rind and lemon suppressed at the level of tendency the growth of rat Walker W-256 carcinoma. The biocomposite from green tea and extract from red vine rind had hampered only Guerin's carcinoma growth and at the tendency had increased the growth of W-256 carcinosarcoma growth. This biocomposite increased also considerably the therapeutic efficiency of cisplatin on Guerin's carcinoma. Studed vegetable biocomposites posesses antiinflammatory and antioxidant properties.

  18. Relationships of pinon juniper woodland expansion and climate trends in the Walker Basin, Nevada

    NASA Astrophysics Data System (ADS)

    Donald, Jonathon

    Landscapes are in constant flux. Vegetation distributions have changed in conjunction with climate, driven by factors such as Milankovitch cycles and atmospheric composition. Until recently, these changes have occurred gradually. Human populations are altering Earth's systems, including atmospheric composition and land use. This is altering vegetation distributions at landscape scales due to changes in species potential niche, as well as current and historical alteration of their realized niche. Vegetation shifts have the potential to be more pronounced in arid and mountainous environments as resources available to plants such as soil moisture are more limiting. In the Great Basin physiographic region of the western United States, woody encroachment of pinon juniper (Pinus monophylla & Juniperus osteosperma) woodlands is well known, but the drivers of its expansion are not well understood across elevational gradients. Predominant theories of future vegetation distribution change due to a changing climate, predict that montane species will move upslope in response to increasing temperatures. In pinon juniper woodlands, the focus has been on downslope movement of woodlands into other ecosystem types. The drivers for this are typically thought to be historical land uses such as grazing and fire exclusion. However, infilling and establishment is occurring throughout its distribution and relatively little attention has been paid to woodland movement uphill. This study focuses on two mountain ranges within the Walker Lake Basin, so as to understand changes occurring along the full gradient of pinon juniper woodlands, from lower to upper treeline, on both the western and eastern side of the ranges. The overall goal of this study was to understand trends of change (increasing, decreasing canopy density) in pinon juniper woodlands and determine if these trends were related to climate change trends. Trends in both vegetation and climate were analyzed for the entire

  19. Walker Circulation, El Niño and La Niña

    NASA Astrophysics Data System (ADS)

    Halpern, D.

    2014-12-01

    Ocean surface wind vector is likely the critical variable to predict onset, maintenance and dissipation of El Niño and La Niña. Analyses of SeaWinds and ASCAT 10-m height (called "surface") vector winds in the Atlantic, Indian and Pacific Oceans from 1°S-1°N during March 2000 - June 2011 revealed the longitudinal distribution of the surface zonal wind component associated with the Walker Circulation. In the Pacific Ocean east of 140°E and west of 85°W, the mean wind direction was westward towards the maritime continent with maximum mean zonal wind speed (- 6.5 m s-1) at 150°W; east of 85°W the mean direction was toward the convection zone over South America. Four El Niños and five La Niñas occurred from March 2000 - June 2011. In the Pacific from 150°E to 160°W, the average El Niño (La Niña) westward wind speed was 2 m s-1 (1 m s-1) smaller (larger) than normal. In the west Pacific, the variation in westward wind speeds in El Niño and La Niña conditions relative to normal conditions would be expected to substantially uplift the thermocline during El Niño compared to La Niña, which is consistent with conventional wisdom. In the east Pacific from 130°W - 100°W, average El Niño westward wind speeds were less than normal and La Niña conditions by 0.5 m s-1 and 1 m s-1, respectively. The "central" Pacific nature of the El Niños may have influenced the smaller difference between El Niño and La Niña westward wind speeds in the east Pacific compared to the west Pacific. Analyses of longitudinal distributions of thermocline depths will be discussed. Surface zonal wind speeds in the Atlantic and Indian Oceans showed no evidence of El Niño and La Niña; surface meridional winds showed an apparent response in the Indian and Pacific Oceans but not in the Atlantic Ocean. At 700-m height, the MISR zonal wind component in the Atlantic, Indian and Pacific Oceans had similar features as those at the surface, except in the east Pacific where the westward

  20. Seasonal Nutrient Dynamics of Foliage and Litterfall on Walker Branch Watershed, a Deciduous Forest Ecosystem

    SciTech Connect

    Grizzard, T. Henderson, G.S. Clebsch, E.

    1999-01-01

    A detailed twelve-month study of litterfall, live foliage biomass, and seasonal nutrient (nitrogen, phosphorus, potassium, calcium, sodium, and magnesium) dynamics in tree components was performed for forest types on Walker Branch Watershed, Oak Ridge, Tennessee. Biomass and nutrient content of foliage, reproductive parts and branches were examined for ten dominant trees in order to assess the relative importance of litterfall in returning nutrients to the forest floor in four different forest types. Litterfall, measured in pine, pine-oak-hickory, oak-hickory, and mesophytic hardwood forests, was separated into three components (leaves, reproductive parts, and branches). Seasonal comparisons of those forest types were made for biomass and nutrient inputs for each component and for total litterfall. Each forest types was characterized by total annual input to the forest floor of biomass and individual nutrients for each component as well as total litterfall. Canonical analysis was performed on the yearly totals to test for significant differences among the forest types. Live foliage from the ten predominant species of trees on the watershed, determined by order of total basal area, was analyzed for biomass, nutrient concentration, and changes in nutrient content through the growth season. Seasonal trends for these variables, including the ranking of nutrient concentrations for spring versus fall, were discussed in relation to differential growth, translocation, and leaching factors. Most of the litterfall in all forest types (77-85%) was in leaves with fall maximum. Reproductive parts (8-14% with spring and fall maxima) and branches (8-11% with no seasonal trend) contributed the remainder. The ranking of nutrient content in litterfall was similar in spring and fall, except for the replacement of nitrogen by calcium in autumn as the predominant nutrient (followed by K > Mg > P > Na). Comparisons were made between weight and nutrient content for living leaves and leaf

  1. Interpretation of simple and cloud-resolving simulations of moist convection radiation interaction with a mock-Walker circulation

    NASA Astrophysics Data System (ADS)

    Bretherton, Christopher S.; Blossey, Peter N.; Peters, Matthew E.

    2006-11-01

    An idealized two-dimensional mock-Walker circulation in the tropical atmosphere forced by prescribed horizontal gradients in sea-surface temperature (SST) is discussed. This model problem includes feedbacks between cumulus convection and tropical large-scale circulations that have proved challenging for global climate models to predict accurately. Three-dimensional cloud-resolving model (CRM) simulations that explicitly simulate turbulent circulations within individual cloud systems across 4,096 and 1,024 km-wide Walker circulations are compared with a simple theoretical model, the Simplified Quasiequilibrium Tropical Circulation Model (SQTCM). This theoretical model combines the weak-temperature-gradient approximation with a unimodal truncation of tropospheric vertical structure coupled to highly simplified formulations of moist precipitating cumulus convection and its cloud-radiative feedbacks. The rainfall, cloud and humidity distribution, circulation strength, energy fluxes and scaling properties are compared between the models. The CRM-simulated horizontal distribution of rainfall and energy fluxes are adequately predicted by the SQTCM. However, the humidity distribution (drier subsidence regions and high-humidity boundary layers in the CRM), vertical structure and domain-size scaling of the circulation differ significantly between the models. For the SQTCM, the concept of gross moist stability related to advection of moist static energy (MSE) out of tropospheric columns by the mean divergent circulation is used to explain the width and intensity of the rainy region. Column MSE budgets averaged across the ascent branch of the simulated Walker circulation provide similar insight into the cloud-resolving simulations after consideration of the more complex horizontal and vertical circulation structure and the role of transient eddies. A nondimensional ascent-region moist stability ratio α, analogous to the SQTCM gross moist stability, is developed. One term of

  2. Magmatic-Tectonic Interactions: Implications for Seismic Hazard Assessment in the Central Walker Lane and Long Valley Caldera Regions

    NASA Astrophysics Data System (ADS)

    Chacko, R.; Hammond, W. C.; Blewitt, G.; Bormann, J. M.

    2014-12-01

    Accurate estimates of fault slip rates based on geodetic data rely on measurements that represent the long-term deformation of the crust. In the Central Walker Lane/Sierra Nevada transition, the Long Valley Caldera region has experienced multiple episodes of uplift and subsidence during the last four decades. The latest episode began in late 2011 and is detectable as a transient signal in the time series of GPS stations around the caldera. These transient signals become more apparent and reveal the extent of the impact on the ambient crustal deformation field of the Walker Lane when the velocity vectors are transformed to a Sierra-Nevada reference frame. Estimating contemporary slip-rates on faults for the purpose of seismic hazard assessment in the region around Long Valley requires detecting and subtracting the transient signals caused by the uplift and subsidence in the caldera. We estimate the geographic extent to which the ambient crustal deformation field is significantly perturbed by ongoing magmatic activity in Long Valley. We present a time variable 3D deformation field constrained by InSAR and GPS observations, and discuss the implications that tectonic-magmatic interaction have for estimates of present-day fault slip-rate. We model the time dependent deformation at Long Valley by analyzing InSAR time series from Envisat and ERS interferograms spanning a period of more than 19 years. We use an analytical volcano deformation source model derived from vertical (GPS) and line of site (InSAR) component of geodetic observations to estimate the horizontal component of the signals associated with magmatic activity beneath the caldera. Previous studies showed that the latest episode of uplift can be modeled with a Mogi source located at a depth of ~6 km with a volume change of 0.03 km3 beneath the resurgent dome. This model predicts a perturbation to the ambient crustal deformation field extending as far as 60 km from the center of the resurgent dome. Thus the

  3. Effect of gossypol and gossypol related compounds on mulberry pyralid (diaphania pyloalis walker, lepidoptera: pyralidae), a pest of the Mulberry Tree

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gossypol, gossypurpurin and diaminogossypol were tested for inhibitory effects against feeding mulberry pyralid larvae (Diaphania pyloalis Walker, Lepidoptera: Pyralidae). The inclusion of very low concentrations of these compounds (10, 50 or 100 µmoles/g) in artificial diets increased the number of...

  4. Postharvest treatment of fresh fruit from California with methyl bromide for postharvest control of light brown apple moth, Epiphyas postvittana (Walker)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide chamber fumigations were evaluated for postharvest control of light brown apple moth (LBAM), Epiphyas postvittana (Walker), in fresh fruit exports. To simulate external feeding, larvae were contained in gas-permeable cages and distributed throughout loads of peaches, plums, nectarines...

  5. Determining thermotolerance of fifth-instar Cydia pomonella (L.) (Lepidoptera: Tortricidae) and Amyelois transitella (Walker) (Lepidoptera: Pyralidae) by three different methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermotolerance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), were studied using two water immersion methods and one dry heat method. The two water immersion methods were: 1) directly immersing in hot w...

  6. Relative roles of differential SST warming, uniform SST warming and land surface warming in determining the Walker circulation changes under global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Li, Tim

    2016-04-01

    Most of CMIP5 models projected a weakened Walker circulation in tropical Pacific, but what causes such change is still an open question. By conducting idealized numerical simulations separating the effects of the spatially uniform sea surface temperature (SST) warming, extra land surface warming and differential SST warming, we demonstrate that the weakening of the Walker circulation is attributed to the western North Pacific (WNP) monsoon and South America land effects. The effect of the uniform SST warming is through so-called "richest-get-richer" mechanism. In response to a uniform surface warming, the WNP monsoon is enhanced by competing moisture with other large-scale convective branches. The strengthened WNP monsoon further induces surface westerlies in the equatorial western-central Pacific, weakening the Walker circulation. The increase of the greenhouse gases leads to a larger land surface warming than ocean surface. As a result, a greater thermal contrast occurs between American Continent and equatorial Pacific. The so-induced zonal pressure gradient anomaly forces low-level westerly anomalies over the equatorial eastern Pacific and weakens the Walker circulation. The differential SST warming also plays a role in driving low-level westerly anomalies over tropical Pacific. But such an effect involves a positive air-sea feedback that amplifies the weakening of both east-west SST gradient and Pacific trade winds.

  7. A new species of Gadirtha Walker (Nolidae: Collomeninae): a proposed biological control agent of Chinese tallow (Triadica sebifera (L.) Small) (Euphorbiaceae) in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gadirtha fusca, new species, is described from Hong Kong. Adult, male and female genitalia, larva, and pupa are described, illustrated, and compared with Gadirtha impingens Walker. Species is a possible biological control agent for Chinese tallow (Triadica sebifera (L.) Small, Euphorbiaceae) in the ...

  8. Hydrologic model based on deep test data from the Walker O No. 1 well, Terminal Geyser, California

    SciTech Connect

    Beall, J.J.

    1981-10-01

    The Shasta Forest No. 1 Well (renamed Walker O No. 1) at Terminal Geyser, California, was reentered and deepened from 1258 to 4008 feet. Temperature logs indicate the well penetrated a laterally flowing thermal aquifer between 1400 and 2200 feet. Large amounts of drilling fluids were lost in that zone. Maximum temperature in the well (10 months after drilling) was 348/sup 0/F at 2000 feet. A large reversed temperature gradient zone occurs below 2400 feet. Bottom hole temperature is 256/sup 0/F. After completion, the well was flowed for about five hours with nitrogen injection at 2000 feet. Samples taken throughout the flow indicate that fluids lost during drilling were not completely recovered. Salinity increased steadily during the flow period. Ratios of Na, K, and Ca were nearly constant, however, and application of Na-K and Na-K-Ca geothermometers indicate these fluids were in equilibrium with rocks at a temperature of 448-449/sup 0/F.

  9. Unusual Ventriculoperitoneal (VP) Shunt Tube Extrusion through Anus in a Child with Dandy Walker Malformation: A Rare Case Report

    PubMed Central

    Gupta, Gulzar; Gupta, Mayank; Kaushal, Rakesh

    2015-01-01

    Aim of this paper is to report a case of extrusion of Ventriculo peritoneal shunt tube through anus in a one year female child ( k/c/o dandy walker malformation ) treated with placement of ventriculo peritoneal shunt for post operative hydrocephalus after excision of Subtorcular occipital meningocoel. The exact cause of such extrusion is not known. Unusual migration of distal catheter tip of VP shunt is a rare and bowel perforation is reported to occur between 0.1% and 0.7%. The possible factors responsible for this complication are thin bowel wall in children, sharp and stiff end of the VP shunt, use of trocar by some surgeons, chronic irritation by the shunt, previous surgery, infection and silicone allergy. In view of the potential for meningitis prompt and aggressive management is essential to avoid morbidity and mortality. PMID:25738035

  10. The influence of ocean surface temperature gradient and continentality on the Walker circulation. II - Prescribed global changes

    NASA Technical Reports Server (NTRS)

    Stone, P. H.; Chervin, R. M.

    1984-01-01

    The series of experiments presently used to investigate the mechanisms responsible for forcing the global Walker circulation features worldwide changes in ocean surface temperatures (OSTs), topography, and/or continents. The primary factor affecting circulation is noted to be the global distribution of continents and oceans; while OST gradients are also important, topography emerges as comparatively unimportant. Continentality and OST gradients force the model atmosphere through the introduction of zonal variations in surface heating. The vertical motions to which they give rise yield moisture convergence and condensation variations which reinforce vertical motions. The forcing by OST gradients is partly nonlocal, and the atmospheric response is effected by continentality. In all cases, vertical motion zonal variations correlate with precipitation.

  11. Evaluation of geodetic and geologic datasets in the Northern Walker Lane-Summary and recommendations of the Workshop

    USGS Publications Warehouse

    Briggs, Richard W.; Hammond, William C.

    2010-01-01

    The Northern Walker Lane comprises a complex network of active faults in northwestern Nevada and northeastern California bound on the west by the Sierra Nevada and on the east by the extensional Basin and Range Province. Because deformation is distributed across sets of discontinuous faults, it is particularly challenging to integrate geologic and geodetic data in the NWL to assess the region's seismic hazard. Recent GPS measurements show that roughly one centimeter per year of relative displacement is accumulating across a zone about 100 km wide at the latitude of Reno, Nevada, but it is not clear where or how much of this strain might ultimately be released in damaging earthquakes. Despite decades of work in the region, the sum of documented late Pleistocene to recent slip rates is distinctly less than the GPS-measured relative displacement.

  12. Quantization of Friedmann-Robertson-Walker spacetimes in the presence of a negative cosmological constant and radiation

    SciTech Connect

    Monerat, G.A.; Silva, E.V. Correa; Oliveira-Neto, G.

    2006-02-15

    In the present work, we quantize three Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and radiation. The models differ from each other by the constant curvature of their spatial sections, which may be positive, negative or zero. They give rise to Wheeler-DeWitt equations for the scale factor which have the form of the Schroedinger equation for the quartic anharmonic oscillator. We find their eigenvalues and eigenfunctions by using a method first developed by Chhajlany and Malnev. After that, we use the eigenfunctions in order to construct wave packets for each case and evaluate the time-dependent expectation value of the scale factors, which are found to oscillate between finite maximum and minimum values. Since the expectation values of the scale factors never vanish, we have an initial indication that these models may not have singularities at the quantum level.

  13. Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon

    PubMed Central

    2016-01-01

    A new technique is used to study a family of time-dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson-Walker (GRW) space-time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in (M¯,g¯). Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems. PMID:27722202

  14. Quantization of Friedmann-Robertson-Walker Spacetimes in the Presence of a Cosmological Constant and Stiff Matter

    NASA Astrophysics Data System (ADS)

    Oliveira-Neto, G.; Monerat, G. A.; Corrêa Silva, E. V.; Neves, C.; Ferreira Filho, L. G.

    2013-09-01

    In the present work, we study the quantum cosmology description of two Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a negative cosmological constant. The models differ from each other by the constant curvature of the spatial sections, taken to be either positive or zero. We work in the Schutz's variational formalism, quantizing the models and obtaining the appropriate Wheeler-DeWitt equations. In these models there are bound states. Therefore, we compute, for each one, the discrete energy spectrum and the corresponding eigenfunctions. After that, we use the eigenfunctions in order to construct wave packets and evaluate the time-dependent expectation values of the scale factors. Each model shows bounded oscillations for the expectation value of the scalar factor, which is never zero, which can be interpreted as an initial indication that these models may not have singularities at the quantum level.

  15. Interstitial deletion of 8q21{yields}22 associated with minor anomalies, congenital heart defect, and Dandy-Walker variant

    SciTech Connect

    Donahue, M.L.; Ryan, R.M.

    1995-03-13

    We describe an infant with a deletion of 8q21{yields}22 who had distinct clinical manifestations including minor facial anomalies, a congenital heart defect, a Dandy-Walker variant, and mild to moderate developmental delay. Her facial characteristics included small, wide-spaced eyes, asymmetric bilateral epicanthal folds, a broad nasal bridge, a {open_quotes}carp-shaped{close_quotes} mouth, micrognathia, and prominent, apparently low-set ears. Three other reports describe children with larger proximal deletions of 8q that include 8q21 and q22. These four children all have similar facial appearance. Of the others reported, one had a congenital heart defect and one had craniosynostosis. This case, in addition to the previously noted three cases, helps in delineating a recognizable syndrome. 12 refs., 3 figs., 1 tab.

  16. Ecology and demographics of hantavirus infections in rodent populations in the Walker River Basin of Nevada and California.

    PubMed

    Boone, J D; Otteson, E W; McGwire, K C; Villard, P; Rowe, J E; St Jeor, S C

    1998-09-01

    To study the ecologic correlates of hantavirus in deer mice (Peromyscus maniculatus), we sampled 114 sites in the Walker River Basin of Nevada and California in 1995-1996. Blood samples were tested for antibody to hantavirus, and a subset of samples was also tested for virus RNA by reverse transcription-polymerase chain reaction. Average prevalence of antibody-positive mice was 17%, with heavier males the most likely to be infected. Antibody prevalence varied within repeatedly sampled sites from 0% to 50% over the course of several months, suggesting possible infection cycles. Although there was no linear correlation between deer mouse density and antibody prevalence on sample sites, more complex relationships between density and prevalence appeared likely. Specifically, infections were less likely where rodent densities were lower than a critical threshold value. However, above this value, density had no effect on prevalence. PMID:9749642

  17. How Do Ants Make Sense of Gravity? A Boltzmann Walker Analysis of Lasius niger Trajectories on Various Inclines

    PubMed Central

    Khuong, Anaïs; Lecheval, Valentin; Fournier, Richard; Blanco, Stéphane; Weitz, Sébastian; Bezian, Jean-Jacques; Gautrais, Jacques

    2013-01-01

    The goal of this study is to describe accurately how the directional information given by support inclinations affects the ant Lasius niger motion in terms of a behavioral decision. To this end, we have tracked the spontaneous motion of 345 ants walking on a 0.5×0.5 m plane canvas, which was tilted with 5 various inclinations by rad ( data points). At the population scale, support inclination favors dispersal along uphill and downhill directions. An ant's decision making process is modeled using a version of the Boltzmann Walker model, which describes an ant's random walk as a series of straight segments separated by reorientation events, and was extended to take directional influence into account. From the data segmented accordingly ( segments), this extension allows us to test separately how average speed, segments lengths and reorientation decisions are affected by support inclination and current walking direction of the ant. We found that support inclination had a major effect on average speed, which appeared approximately three times slower on the incline. However, we found no effect of the walking direction on speed. Contrastingly, we found that ants tend to walk longer in the same direction when they move uphill or downhill, and also that they preferentially adopt new uphill or downhill headings at turning points. We conclude that ants continuously adapt their decision making about where to go, and how long to persist in the same direction, depending on how they are aligned with the line of maximum declivity gradient. Hence, their behavioral decision process appears to combine klinokinesis with geomenotaxis. The extended Boltzmann Walker model parameterized by these effects gives a fair account of the directional dispersal of ants on inclines. PMID:24204636

  18. Effect of Walker 256 tumor growth on intestinal absorption of leucine, methionine and glucose in newly weaned and mature rats.

    PubMed

    Gomes-Marcondes, M C; Honma, H N; Areas, M A; Cury, L

    1998-10-01

    In tumor-bearing rats, most of the serum amino acids are used for synthesis and oxidation processes by the neoplastic tissue. In the present study, the effect of Walker 256 carcinoma growth on the intestinal absorption of leucine, methionine and glucose was investigated in newly weaned and mature rats. Food intake and carcass weight were decreased in newly weaned (NT) and mature (MT) rats bearing Walker 256 tumor in comparison with control animals (NC and MC). The tumor/carcass weight ratio was higher in NT than in MT rats, whereas nitrogen balance was significantly decreased in both as compared to control animals. Glucose absorption was significantly reduced in MT rats (MT = 47.3 +/- 4.9 vs MC = 99.8 +/- 5.3 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05) but this fact did not hamper the evolution of cancer. There was a significant increase in methionine absorption in both groups (NT = 4.2 +/- 0.3 and MT = 2.0 +/- 0.1 vs NC = 3.7 +/- 0.1 and MC = 1.2 +/- 0.2 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05), whereas leucine absorption was increased only in young tumor-bearing rats (NT = 8.6 +/- 0.2 vs NC = 7.7 +/- 0.4 nmol min-1 cm-1, Kruskal-Wallis test, P < 0.05), suggesting that these metabolites are being used for synthesis and oxidation processes by the neoplastic cells, which might ensure their rapid proliferation especially in NT rats.

  19. Optimal handgrip height of four-wheeled walker on various road conditions to reduce muscular load for elderly users with steady walking.

    PubMed

    Takanokura, Masato

    2010-03-22

    A four-wheeled walker is a valuable tool for assisting elderly persons with walking. The handgrip height is one of the most important factor determining the usefulness of the walker. However, the optimal handgrip height for elderly users has not been considered from a biomechanical viewpoint. In this study, the handgrip height was optimized by a two-dimensional mechanical model to reduce muscular loads in the lower body as well as in the upper body with various road conditions during steady walking. A critical height of the handgrip existed at 48% of the body height for the user regardless of gender and body dimension. A lower handgrip relieved muscular load for stooping users with a lower standing height. The stooping user pushed the handgrip strongly in the perpendicular direction by leaning the upper body on the walker. However, upright users with a higher standing height should use a four-wheeled walker with a higher handgrip for maintaining his or her upright posture. For downhill movement, the optimal handgrip height depended on the slope angle and the friction coefficient between the road and the wheels of the walker. On a low-friction downhill such as asphalt with a steeper slope angle, the user was required to maintain an erect trunk with a higher handgrip and to press on the handgrip strongly in the perpendicular direction. Movement on a low-friction road was easier for users on a flat road and an uphill road, but it compelled distinct effort from users when moving downhill.

  20. Effect of alpha tocopherol acetate in Walker 256/B cells-induced oxidative damage in a rat model of breast cancer skeletal metastases.

    PubMed

    Badraoui, Riadh; Blouin, Stéphane; Moreau, Marie Françoise; Gallois, Yves; Rebai, Tarek; Sahnoun, Zouhaier; Baslé, Michel; Chappard, Daniel

    2009-12-10

    The pathophysiological changes and the oxidative-antioxidative status were evaluated in the bone microenvironment of rat inoculated with Walker 256/B mammary gland carcinoma cells, and used alpha-tocopherol acetate (ATA) as a countermeasure. Walker 256/B cells were injected into the right femora of aged male rats. Animals were randomized into three groups: 12 rats were injected with saline (control group); 14 rats were injected with Walker 256/B cells (5x10(4)) in the medullar cavity (W256 group); 14 rats were inoculated with Walker 256/B cells and treated with ATA (45mg/kg BW) (W256+ATA group). After 20 days, rats were euthanized and the femurs were radiographed. Micro architectural parameters were measured by microcomputed tomography and histology. Serum, bone and bone marrow were evaluated for oxidative damage. In parallel, cell cultures were done in the presence of ATA and ROS were measured by fluorescence; apoptotic cells were determined in parallel. W256 groups had osteolytic damages with marked resorption of cortical and trabecular bone. W256+ATA animals presented marked osteosclerotic areas associated with tumor necrosis areas inside the bone cavity. Levels of lipid peroxidation and protein oxidation were found to increase in W256 rats; a significant reduction in SOD and GSH-p activities was also observed. W256+ATA group had significantly reduced oxidative damage, but not reversed back to the control levels. The present study shows that Walker 256/B cells induce skeletal metastases associated with oxidative damage in the bone microenvironment. ATA reduced the oxidative stress damage, enhanced osteosclerosis and tumor cell apoptosis both in vitro and in vivo.

  1. The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

    NASA Astrophysics Data System (ADS)

    Kell, Anna Marie

    The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery

  2. Changes in energy cost and total external work of muscles in elite race walkers walking at different speeds.

    PubMed

    Chwała, Wiesław; Klimek, Andrzej; Mirek, Wacław

    2014-12-01

    The aim of the study was to assess energy cost and total external work (total energy) depending on the speed of race walking. Another objective was to determine the contribution of external work to total energy cost of walking at technical, threshold and racing speed in elite competitive race walkers. The study involved 12 competitive race walkers aged 24.9 4.10 years with 6 to 20 years of experience, who achieved a national or international sports level. Their aerobic endurance was determined by means of a direct method involving an incremental exercise test on the treadmill. The participants performed three tests walking each time with one of the three speeds according to the same protocol: an 8-minute walk with at steady speed was followed by a recovery phase until the oxygen debt was repaid. To measure exercise energy cost, an indirect method based on the volume of oxygen uptake was employed. The gait of the participants was recorded using the 3D Vicon opto-electronic motion capture system. Values of changes in potential energy and total kinetic energy in a gate cycle were determined based on vertical displacements of the centre of mass. Changes in mechanical energy amounted to the value of total external work of muscles needed to accelerate and lift the centre of mass during a normalised gait cycle. The values of average energy cost and of total external work standardised to body mass and distance covered calculated for technical speed, threshold and racing speeds turned out to be statistically significant (p 0.001). The total energy cost ranged from 51.2 kJ.m-1 during walking at technical speed to 78.3 kJ.m-1 during walking at a racing speed. Regardless of the type of speed, the total external work of muscles accounted for around 25% of total energy cost in race walking. Total external work mainly increased because of changes in the resultant kinetic energy of the centre of mass movement.

  3. Studying methane migration mechanisms at Walker Ridge, Gulf of Mexico, via 3D methane hydrate reservoir modeling

    SciTech Connect

    Nole, Michael; Daigle, Hugh; Mohanty, Kishore; Cook, Ann; Hillman, Jess

    2015-12-15

    We have developed a 3D methane hydrate reservoir simulator to model marine methane hydrate systems. Our simulator couples highly nonlinear heat and mass transport equations and includes heterogeneous sedimentation, in-situ microbial methanogenesis, the influence of pore size contrast on solubility gradients, and the impact of salt exclusion from the hydrate phase on dissolved methane equilibrium in pore water. Using environmental parameters from Walker Ridge in the Gulf of Mexico, we first simulate hydrate formation in and around a thin, dipping, planar sand stratum surrounded by clay lithology as it is buried to 295mbsf. We find that with sufficient methane being supplied by organic methanogenesis in the clays, a 200x pore size contrast between clays and sands allows for a strong enough concentration gradient to significantly drop the concentration of methane hydrate in clays immediately surrounding a thin sand layer, a phenomenon that is observed in well log data. Building upon previous work, our simulations account for the increase in sand-clay solubility contrast with depth from about 1.6% near the top of the sediment column to 8.6% at depth, which leads to a progressive strengthening of the diffusive flux of methane with time. By including an exponentially decaying organic methanogenesis input to the clay lithology with depth, we see a decrease in the aqueous methane supplied to the clays surrounding the sand layer with time, which works to further enhance the contrast in hydrate saturation between the sand and surrounding clays. Significant diffusive methane transport is observed in a clay interval of about 11m above the sand layer and about 4m below it, which matches well log observations. The clay-sand pore size contrast alone is not enough to completely eliminate hydrate (as observed in logs), because the diffusive flux of aqueous methane due to a contrast in pore size occurs slower than the rate at which methane is supplied via organic methanogenesis

  4. Similar and Contrasting Response of Rifting and Transtension in the Gulf of California and Walker Lane to Preceding Arc Magmatism

    NASA Astrophysics Data System (ADS)

    Henry, C. D.; Faulds, J. E.

    2006-12-01

    The Gulf of California (GC) and Walker Lane (WL) have undergone strikingly similar development with strike- slip faulting following initial extension. They differ significantly in the amount of Pacific-North American plate motion taken up by each: essentially all relative motion in the GC and ~25% in the WL. In both areas, ancestral arc magmatism preceded and probably focused deformation, perhaps because heating and/or hydration weakened the lithosphere. However, differences in migration of the Rivera (RTJ) and Mendocino triple junctions (MTJ) related to differences in the orientation of plate boundaries determined how strike-slip faulting developed. Abrupt southward jumps in the RTJ led to abrupt cessation of magmatism over arc lengths of as much as 1000 km and initiation of east-northeast extension within the future GC. The best known jump was at ~13 Ma, but an earlier jump occurred at ~18 Ma. Arc magmatism has been best documented in Baja California, Sonora, and Nayarit, although Baja constituted the most-trenchward fringe of the ancestral arc. New and published data indicate that Sinaloa underwent a similar history of arc magmatism. The greatest volume of the arc immediately preceding RTJ jumps was probably in mainland Mexico. Arc magmatism shut off following these jumps, extension began in the future GC, and strike-slip faulting either followed or accompanied extension in the GC. In contrast, the MTJ migrated progressively northward. New and published data indicate magmatism generally shut off coincident with this retreat, but distinct nodes or zones of magmatism, presumably unrelated to subduction, persisted or initiated after arc activity ceased. We have suggested that the WL has grown progressively northward, following the retreating arc, and that the northern WL is its youngest part. However, the timing of initiation of strike-slip faulting in most of the WL is poorly known and controversial. Testing our hypothesis requires determining initiation and

  5. Description of a new species of Oligosita Walker (Chalcidoidea: Trichogrammatidae), egg parasitoid of Balclutha brevis Lindberg (Homoptera: Cicadellidae) living on Pennisetum setaceum, from Italy.

    PubMed

    Bella, Salvatore; Cupani, Sebastiano; D'urso, Vera; Laudonia, Stefania; Sinno, Martina; Viggiani, Gennaro

    2015-01-01

    A new species of Oligosita Walker (Chalcidoidea: Trichogrammatidae), O. balcluthae Viggiani et Laudonia n. sp., is described as a parasitoid of the eggs of Balclutha brevis Lindberg (Homoptera: Cicadellidae) associated with crimson fountain grass, Pennisetum setaceum (Poaceae) in Italy. Morphological features and biology of the new species are discussed and illustrated. The 28S-D2 and ITS2 regions were successfully amplified and sequenced. PMID:26624644

  6. Effect of a high-intensity exercise training on the metabolism and function of macrophages and lymphocytes of walker 256 tumor bearing rats.

    PubMed

    Bacurau, Aline Villa Nova; Belmonte, Mônica Aparecida; Navarro, Francisco; Moraes, Milton Rocha; Pontes, Francisco Luciano; Pesquero, Jorge Luiz; Araújo, Ronaldo Carvalho; Bacurau, Reury Frank Pereira

    2007-11-01

    Epidemiologic studies suggest that moderately intense training promotes augmented immune function, whereas strenuous exercise can cause immunosupression. Because the combat of cancer requires high immune function, high-intensity exercise could negatively affect the host organism; however, despite the epidemiologic data, there is a lack of experimental evidence to show that high-intensity training is harmful to the immune system. Therefore, we tested the influence of high-intensity treadmill training (10 weeks, 5 days/week, 30 mins/day, 85% VO(2)max) on immune system function and tumor development in Walker 256 tumor-bearing Wistar rats. The metabolism of glucose and glutamine in lymphocytes and macrophages was assessed, in addition to some functional parameters such as hydrogen peroxide production, phagocytosis, and lymphocyte proliferative responses. The metabolism of Walker 256 cells was also investigated. Results demonstrated that high-intensity training increased the life span of tumor-bearing rats, promoted a reduction in tumor mass, and prevented indicators of cachexia. Several changes, such as a reduction in body weight and food intake and activation of glutamine metabolism in macrophages and lymphocytes induced by the presence of Walker 256 tumor, were prevented by high intensity training. The reduction in tumor growth was associated with an impairment of tumor cell glucose and glutamine metabolism. These data suggest that high-intensity exercise training may be a viable strategy against tumors. PMID:17959841

  7. Significant Accommodation of NW-Directed Right Lateral Shear Across the Northern Walker Lane, Nevada by the Pyramid Lake Fault Zone

    NASA Astrophysics Data System (ADS)

    Briggs, R. W.; Wesnousky, S. G.

    2002-12-01

    Geodetic measurements indicate that 4-8 mm/year of northwest directed, right lateral shear is accumulating across the northern Walker Lane at the latitude of Reno, Nevada (Thatcher et al., 1999). The Pyramid Lake fault zone is located at the latitude of Reno within the northern Walker Lane. The northwest trending, right lateral fault exhibits features typical of strike slip faults, including laterally offset geomorphic features, opposite-facing scarps, and linear ridges and depressions. The fault zone is ideally oriented to accommodate northwest directed right lateral shear. Measurements of laterally offset geomorphic features, including channel thalwegs, channel banks, and prominent ridges are interpreted to show the fault slip rate is at minimum 1mm/yr and probably >=3 mm/yr during the latest Pleistocene and Holocene. Thus the Pyramid Lake fault zone appears to accommodate a significant portion (40-75%) of the geodetically measured strain at its latitude across the northern Walker Lane. Radiocarbon and tephra collected from trench exposures are placing limits on the recurrence and recency of rupture along the fault.

  8. Cytotoxicity of aniline mustard glucuronide alone or in a combination with glucose in Walker cells in culture and sarcoma-180 tumour bearing animals.

    PubMed

    Deliconstantinos, G; Ramantanis, G; Todorou, D K

    1983-01-01

    The effect of aniline mustard glucuronide (AMG), p-hydroxyaniline mustard (HAM), and aniline mustard (AM), on Walker ascites tumour cells in vitro showed that AM in about 80 times more toxic than its glucuronide but HAM is at least 800 times more toxic. A non toxic dose of AMG became completely lethal to Walker tumour cells in vitro, if bovine liver beta-glucuronidase was added to the incubation medium. Prior treatment of Walker tumour cells in vitro with glucose, increased the breakdown of AMG to HAM within the intact cells, while a non-toxic dose of the glucuronide became completely lethal to cells pretreated with glucose. The administration of AMG in combination with glucose to animals bearing the highly resistant to alkylating agents Sarcoma-180 tumour, increased the toxicity of the glucuronide but produced a slight effect on tumour growth. Glucose administration in Sarcoma-180 and ADJ/PC6 tumour bearing animals did not alter the tumour intracellular pH determined in vivo indirectly from the distribution of the weak non-metabolizable organic acid 5,5-dimethyl-2,4-oxazolinedione (DMO) between intra- and extra-cellular water. The present data suggest that the combination of aniline mustard glucuronide with glucose, could be effective in those tumours which have a high beta-glucuronidase activity and a lower tumour intracellular pH could be induced by glucose.

  9. Effects of Total Ginsenosides on the Feeding Behavior and Two Enzymes Activities of Mythimna separata (Walker) Larvae

    PubMed Central

    Zhang, Ai-Hua; Tan, Shi-Qiang; Zhao, Yan; Lei, Feng-Jie; Zhang, Lian-Xue

    2015-01-01

    Ginsenosides, the main effective components of Panax ginseng C.A. Meyer and Panax quinquefolius L., are important allelochemicals of ginseng. Although many studies have targeted the pharmacological, chemical, and clinical properties of ginsenosides, little is known about their ecological role in ginseng population adaptation and evolution. Pests rarely feed on ginseng, and it is not known why. This study investigated the effects of total ginsenosides on feeding behavior and activities of acetylcholinesterase (AChE) and glutathione s-transferase (GST) in Mythimna separata (Walker) larvae. The results showed that the total ginsenosides had significant antifeeding activity against M. separata larvae, determined by nonselective and selective antifeeding bioassays. In addition, the total ginsenosides had inhibitory effects on the activities of GST and AChE. The antifeeding ratio was the highest at 8 h, then decreased, and was the lowest at 16 h. Both GST and AChE activities decreased from 0 h to 48 h in all total ginsenosides treatments but increased at 72 h. Total ginsenosides had antifeeding activity against M. separata larvae and inhibitory effects on the activities of GST and AChE. PMID:26074991

  10. Competitive Interactions between Immature Stages of Bactrocera cucurbitae (Coquillett) and Bactrocera tau (Walker) (Diptera: Tephritidae) under Laboratory Conditions.

    PubMed

    Shen, K; Hu, J; Wu, B; An, K; Zhang, J; Liu, J; Zhang, R

    2014-08-01

    The melon fly, Bactrocera cucurbitae (Coquillett), and the pumpkin fly, Bactrocera tau (Walker), are economically important pests that attack mainly cucurbitacean fruits. The two fruit fly species have similar natural distributions, host ranges, and population growth capacities. This study was designed to assess the asymmetrical competitions through resource exploitation between the larvae of B. cucurbitae and B. tau at different density levels and temperatures, and on different hosts by comparing the relative effects of interspecific and intraspecific interactions on four life history parameters: survival rate, puparial mass, puparial duration, and developmental duration. Our results showed that intraspecific and interspecific competitions occurred under some laboratory conditions, and B. cucurbitae took advantage over B. tau at the high-density level and at low and high temperatures on pumpkin, bitter gourd, and bottle gourd when interspecific competition took place. Intraspecific and interspecific competitions mainly affected the puparial mass and the survival rate of the two fruit fly species but had no marked effect on the puparial duration or development duration. PMID:27193811

  11. Replacement by Caenis diminuta walker (ephemeroptera:caenidae) in the mayfly community structure of a thermally-stressed, southeastern stream

    SciTech Connect

    Poff, N L; Matthews, R A

    1984-01-01

    Mayfly community structure on sycamore and sweetgum leaf packs in a thermally-stressed, post-thermal and an unstressed stream were compared. Leaves were colonized over an 11 wk (77 d) period from December 1982 to March 1983. Degree-days (> 0/sup 0/C) accumulated were 1014, 638 and 627 for the thermally-stressed, post-thermal and unstressed streams, respectively. Significant differences in mayfly community structure were found between the thermally-stressed vs. the post-thermal and unstressed streams with respect to both Stenonema spp. and Caenis diminuta Walker. No significant differences in community structure were found between the two leaf species. Stenonema spp. dominated the mayfly fauna over the sampling period for both the unstressed (68%) and post-thermal (98%) streams; however, C. diminuta replaced Stenonema spp. as the dominant mayfly (88%) within leaf packs from the stream receiving thermal effluent. Additional data suggest C. diminuta is tolerant of rapidly fluctuating thermal regimes (..delta.. T of up to 11/sup 0/C in 1 h) and high temperatures (up to 40/sup 0/C). 30 references, 3 figures, 3 tables.

  12. Animal asymmetry and human heredity: dextrality, tool use and language in evolution--10 years after Walker (1980).

    PubMed

    Bradshaw, J L

    1991-02-01

    At the time of the last major review on this subject in the British Journal of Psychology (Walker, 1980) there was, with a few notable exceptions, little evidence of anatomical or behavioural asymmetries in non-human species at all comparable to our own. In the past decade the picture has changed dramatically, and now includes invertebrates from the Cambrian formations of half a billion years ago, many species of birds, rats and mice, antelopes, cats, dogs, whales, and primates. Asymmetries may differ as a function of sex (including hormone status-females of many species including humans appearing more lateralized at a motor level), developmental status and environmental influences. Effects may be manifest anatomically (limb or brain dimensions), or at a sensory, cognitive or motor level (paw preference, turning biases). A recurring observation across species is that the right hemisphere seems to be weakly specialized for spatial and emotional roles, and the left for learning, discriminatory and communicatory functions. Three million years ago our hominid ancestors were more or less fully bipedal, developed the first stone tools and were dextral in manipulating them. However, tool use seems not to have driven the evolution of language, our other strongly lateralized capacity. Evolutionary scenarios for bipedalism, tool use and language are discussed, together with the question of whether human language is continuous, in an evolutionary sense, with earlier primate call systems.

  13. A rat model of bone cancer pain induced by intra-tibia inoculation of Walker 256 mammary gland carcinoma cells

    SciTech Connect

    Mao-Ying, Q.-L.; Zhao Jun; Dong Zhiqiang; Wang Jun; Yu Jin; Yan Minfen; Zhang Yuqiu; Wu Gencheng; Wang Yanqing . E-mail: wangyanqing@shmu.edu.cn

    2006-07-14

    This study described a modified rat model of bone cancer pain. Syngeneic Walker 256 mammary gland carcinoma cells were injected into the tibia medullary cavity via intercondylar eminence. Series of tests were carried out including bone radiology, bone histology, ambulatory pain, thermal hyperalgesia, mechanical allodynia, weight bearing ability, and electrophysiological recording from primary afferent fibers. The rats inoculated with carcinoma cells showed significant ambulatory pain, mechanical allodynia, and reduction in weight bearing, as well as increased incidence of spontaneous activity in A{beta} fibers in affected limb, whereas PBS (vehicle) or heat-killed cells (sham) injected rats showed no significant difference in comparison to normal rats. The pain hypersensitive behaviors were aggravated with time and destruction of bone. Interestingly, mechanical allodynia was also observed in the contralateral limb, indicating the involvement of 'mirror image' pain in bone cancer pain. In summary, the present study provided a useful and easily established rat model of bone cancer pain which will contribute to further study of the mechanisms underlying cancer pain.

  14. New Test of the Friedmann-Lemaître-Robertson-Walker Metric Using the Distance Sum Rule.

    PubMed

    Räsänen, Syksy; Bolejko, Krzysztof; Finoguenov, Alexis

    2015-09-01

    We present a new test of the validity of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, based on comparing the distance from redshift 0 to z(1) and from z(1) to z(2) to the distance from 0 to z(2). If the Universe is described by the FLRW metric, the comparison provides a model-independent measurement of spatial curvature. The test relies on geometrical optics, it is independent of the matter content of the Universe and the applicability of the Einstein equation on cosmological scales. We apply the test to observations, using the Union2.1 compilation of supernova distances and Sloan Lens ACS Survey galaxy strong lensing data. The FLRW metric is consistent with the data, and the spatial curvature parameter is constrained to be -1.22<Ω(K0)<0.63, or -0.08<Ω(K0)<0.97 with a prior from the cosmic microwave background and the local Hubble constant, though modeling of the lenses is a source of significant systematic uncertainty. PMID:26382671

  15. Regulation of migration in Mythimna separata (Walker) in China: a review integrating environmental, physiological, hormonal, genetic, and molecular factors.

    PubMed

    Jiang, Xingfu; Luo, Lizhi; Zhang, Lei; Sappington, Thomas W; Hu, Yi

    2011-06-01

    Each year the Mythimna separate (Walker), undertakes a seasonal, long-distance, multigeneration roundtrip migration between southern and northern China. Despite its regularity, the decision to migrate is facultative, and is controlled by environmental, physiological, hormonal, genetic, and molecular factors. Migrants take off on days 1 or 2 after eclosion, although the preoviposition period lasts ≈7 d. The trade-offs among the competing physiological demands of migration and reproduction are coordinated in M. separata by the "oogenesis-flight syndrome." Larvae that experience temperatures above or below certain thresholds accompanied by appropriate humidity, short photoperiod, poor nutrition, and moderate density tend to develop into migrants. However, there is a short window of sensitivity within 24 h after adult eclosion when migrants can be induced to switch to reproductive residents if they encounter extreme environmental factors including starvation, low temperature and long photoperiod. Juvenile hormone (JH) titer is low before migration but high titers are associated with termination of migratory behavior and the switch to reproduction. Early release of JH by the corpora allata in environmentally stressed 1-d old adults, otherwise destined by larval conditions to be migrants, switches them to residents. Offspring inherit parental additive genetic effects governing migratory behavior. However, they also retain flexibility in expression of both flight and reproductive life history traits. The insect neuropeptide, allatotropin, which activates corpora allata to synthesize JH, controls adult flight and reproduction. Future research directions to better understand regulation of migration in this species are discussed.

  16. Histopathological effects and immunolocalization of periplocoside NW from Periploca sepium Bunge on the midgut epithelium of Mythimna separata Walker larvae.

    PubMed

    Feng, Mingxing; Shi, Baojun; Zhao, Yanchao; Hu, Zhaonong; Wu, Wenjun

    2014-10-01

    Periplocoside NW (PSNW) with pregnane glycoside skeleton is a novel insecticidal compound isolated from the root bark of Periploca sepium Bunge. This compound has a potent stomach poisoning activity against several insect pests. In this study, we observed the intoxication symptoms, investigated the histopathological effects and carried out immuno-electron microscopic localization of PSNW on the midgut epithelium of oriental armyworm Mythimna separata Walker larvae for better understanding its action mechanism against insects. Ultrastructural observations showed that cell damages caused by PSNW in the midgut of M. separata larvae are related to the degeneration of brush border microvilli. The dissolution of cytoskeletal structures in the interior and on the surface of microvilli was responsible for the decrease in size and eventual disappearance of microvilli when bubbles of cytoplasmic substances protrude into the midgut lumen of M. separata, thus resulting in cell death. The immuno-electron microscopic localization research showed that gold particle appeared on the microvilli layer of the midgut of M. separate larvae firstly. The density of gold particle gradually added with the time, and finally microvilli layer was destructed severely. Meantime, the gold particles were also presented to the intracellular organelle membrane and the organelles also were destructed. Therefore, we proposed that this membrane system on insect midgut epithelium cells is the initial acting site of PSNW against insects.

  17. Exploring the Midgut Transcriptome and Brush Border Membrane Vesicle Proteome of the Rice Stem Borer, Chilo suppressalis (Walker)

    PubMed Central

    Peng, Chuanhua; Wang, Xiaoping; Li, Fei; Lin, Yongjun

    2012-01-01

    The rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), is one of the most detrimental pests affecting rice crops. The use of Bacillus thuringiensis (Bt) toxins has been explored as a means to control this pest, but the potential for C. suppressalis to develop resistance to Bt toxins makes this approach problematic. Few C. suppressalis gene sequences are known, which makes in-depth study of gene function difficult. Herein, we sequenced the midgut transcriptome of the rice stem borer. In total, 37,040 contigs were obtained, with a mean size of 497 bp. As expected, the transcripts of C. suppressalis shared high similarity with arthropod genes. Gene ontology and KEGG analysis were used to classify the gene functions in C. suppressalis. Using the midgut transcriptome data, we conducted a proteome analysis to identify proteins expressed abundantly in the brush border membrane vesicles (BBMV). Of the 100 top abundant proteins that were excised and subjected to mass spectrometry analysis, 74 share high similarity with known proteins. Among these proteins, Western blot analysis showed that Aminopeptidase N and EH domain-containing protein have the binding activities with Bt-toxin Cry1Ac. These data provide invaluable information about the gene sequences of C. suppressalis and the proteins that bind with Cry1Ac. PMID:22666467

  18. Baby walker injury awareness among grade-12 girls in a high-prevalence Arab country in the Middle East.

    PubMed

    Grivna, Michal; Barss, Peter; Al-Hanaee, Amna; Al-Dhahab, Ayesha; Al-Kaabi, Fatima; Al-Muhairi, Shamma

    2015-03-01

    Baby walkers (BWs) are a consumer product frequently associated with infant injuries. With little research in the Middle East and few population studies anywhere, female students in grade 12 in the United Arab Emirates were surveyed, assessing the prevalence of use, perceived safety, and interventions. The study population included grade-12 students in a large UAE city. Multistage random sampling selected 4/8 female Arab government schools and 3 classes each from science and arts tracks for interview by self-administered questionnaire. Response was 100%, with a total of 696 students, 55% (n = 385) of whom were Emirati citizens; 90% (n = 619) of the families used/had used BWs. Among the reasons for use, 92% reported "keeping baby safe," with 11% perceiving BWs as very safe and 74% as moderately safe. Only 16% perceived that BWs could cause injuries. Despite causing many injuries, including fatalities, BWs were perceived to be safe and used by nearly all families. Effective education of professionals, patients, the public, and decision makers is needed. Governments should consider countermeasures such as prohibiting importation, sales, and advertising, together with public education and provision of stationary activity centers. PMID:24595658

  19. Late Neogene slip transfer and extension within the curved Whisky Flat fault system central Walker Lane, west-central Nevada

    NASA Astrophysics Data System (ADS)

    Biholar, Alexander Kenneth Casian

    In Whisky Flat of west-central Nevada, northwest-striking faults in the Walker Lane curve to east-northeast orientations at the northern limits of the Mina deflection. This curve in strike results in the formation of ˜685 m deep depression bounded by north-south convex to the east range-front faults that at the apex of fault curvature are bisected at a high angle by a structural stepover. We use the vertical offset of a late Miocene erosional surface mapped in the highlands and inferred from gravity depth inversion in the basin to measure the magnitude of displacement on faults. A N65°W extensional axis determined through fault-slip inversion is used to constrain the direction in displacement models. Through the use of a forward rectilinear displacement model, we document that the complex array of faults is capable of developing with broadly contemporaneous displacements on all structures since the opening of the basin during the Pliocene.

  20. Abscopal antitumor immune effects of magnet-mediated hyperthermia at a high therapeutic temperature on Walker-256 carcinosarcomas in rats

    PubMed Central

    WANG, HUI; ZHANG, LI; SHI, YINGRUI; JAVIDIPARSIJANI, SARA; WANG, GUIRONG; LI, XIAO; OUYANG, WEIWEI; ZHOU, JUMEI; ZHAO, LINGYUN; WANG, XIAOWEN; ZHANG, XIAODONG; GAO, FUPING; LIU, JINGSHI; LUO, JUNMING; TANG, JINTIAN

    2014-01-01

    The abscopal effect has previously been described in various tumors and is associated with radiation therapy and hyperthermia, with possible underlying mechanisms explaining each observed case. In the present study, we aimed to investigate the antitumor effects of magnet-mediated hyperthermia on Walker-256 carcinosarcomas in rats at two different temperature ranges (42–46°C and 50–55°C). We also aimed to identify whether a higher therapeutic temperature of magnetic-mediated hyperthermia improves the abscopal antitumor effects, where localised irradiation of the tumor causes not only the irradiated tumor to shrink, but also tumors located far from the area of irradiation. Following induction of carcinosarcoma in both sides of the body, magnet-mediated hyperthermia was applied to one side only, leaving the other side as a control. The changes in tumor growth were observed. Our results demonstrated that magnet-mediated hyperthermia at a higher temperature inhibited the growth of carcinosarcoma at the site of treatment. Furthermore, the growth of the carcinosarcoma on the untreated side was also inhibited. The expression levels of proliferating cell nuclear antigen were decreased in the hyperthermia group, which was more significant in the higher temperature test group. Flow cytometric analysis showed an increased number of CD4- and CD8-positive T cells, and enzyme-linked immunosorbent assay showed increased levels of interferon-γ and interleukin-2 in the higher temperature group. These results suggested that magnet-mediated hyperthermia at a higher temperature (50–55°C) can improve the abscopal antitumor effects and stimulate a greater endogenous immune response in carcinosarcoma-bearing rats. PMID:24527084

  1. Abscopal antitumor immune effects of magnet-mediated hyperthermia at a high therapeutic temperature on Walker-256 carcinosarcomas in rats.

    PubMed

    Wang, Hui; Zhang, Li; Shi, Yingrui; Javidiparsijani, Sara; Wang, Guirong; Li, Xiao; Ouyang, Weiwei; Zhou, Jumei; Zhao, Lingyun; Wang, Xiaowen; Zhang, Xiaodong; Gao, Fuping; Liu, Jingshi; Luo, Junming; Tang, Jintian

    2014-03-01

    The abscopal effect has previously been described in various tumors and is associated with radiation therapy and hyperthermia, with possible underlying mechanisms explaining each observed case. In the present study, we aimed to investigate the antitumor effects of magnet-mediated hyperthermia on Walker-256 carcinosarcomas in rats at two different temperature ranges (42-46°C and 50-55°C). We also aimed to identify whether a higher therapeutic temperature of magnetic-mediated hyperthermia improves the abscopal antitumor effects, where localised irradiation of the tumor causes not only the irradiated tumor to shrink, but also tumors located far from the area of irradiation. Following induction of carcinosarcoma in both sides of the body, magnet-mediated hyperthermia was applied to one side only, leaving the other side as a control. The changes in tumor growth were observed. Our results demonstrated that magnet-mediated hyperthermia at a higher temperature inhibited the growth of carcinosarcoma at the site of treatment. Furthermore, the growth of the carcinosarcoma on the untreated side was also inhibited. The expression levels of proliferating cell nuclear antigen were decreased in the hyperthermia group, which was more significant in the higher temperature test group. Flow cytometric analysis showed an increased number of CD4- and CD8-positive T cells, and enzyme-linked immunosorbent assay showed increased levels of interferon-γ and interleukin-2 in the higher temperature group. These results suggested that magnet-mediated hyperthermia at a higher temperature (50-55°C) can improve the abscopal antitumor effects and stimulate a greater endogenous immune response in carcinosarcoma-bearing rats.

  2. Lidar-Based Mapping of Late Quaternary Faulting Along the Grizzly Valley Fault, Walker Lane Seismic Belt, California

    NASA Astrophysics Data System (ADS)

    Hitchcock, C. S.; Hoirup, D. F.; Barry, G.; Pearce, J.; Glick, F.

    2012-12-01

    The Grizzly Valley fault (GVF) is located within the northern Walker Lane, a zone of right-lateral shear between the Sierra Nevada and the Basin and Range in Plumas County. The GVF extends southeasterly from near Mt. Ingalls along the eastern side of Lake Davis. It may partially connect with the Hot Creek fault within Sierra Valley and extend south to Loyalton with an overall approximate length of 50 km. Comparison of high-resolution topography developed from LiDAR data with published bedrock geologic mapping documents the presence of geomorphic features that provide information on fault activity of the GVF. Field mapping verified tectonically deformed and offset late Quaternary surfaces identified on bare-earth LiDAR imagery across the GVF within glacial deposits on the eastern margin of Lake Davis, and alluvial deposits in Sierra Valley. Along the GVF, conspicuous geomorphic and hydrologic features include scarps in alluvial surfaces, elongated depressions aligned with adjacent linear escarpments, truncated bedrock spurs, closed depressions, linear swales, right-lateral deflections of creeks and river courses, and shutter ridges, as well as springs and linear seeps consistent with right-lateral strike-slip faulting. The discontinuous nature of observed fault traces combined with the apparent down-to-the-west offset of alluvial surfaces at the southern and northern ends of the eastern margin of Lake Davis are consistent with a broad bend or step over in the fault. Scarp profiles of apparently faulted surfaces extracted from LiDAR data document vertical offsets of up to 14 m. Our study suggest that the GVF is an oblique, right-lateral fault that has been active in the late Quaternary. This study complements on-going investigations by DWR to assess the impact of seismic hazards on State Water Project infrastructure.

  3. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    NASA Astrophysics Data System (ADS)

    Williams, A. Park; Funk, Chris

    2011-12-01

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E-140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980-2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the `long-rains' season of March-June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more `El Niño-like' conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

  4. A Deletion in the VLDLR Gene in Eurasier Dogs with Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation (DWLM)

    PubMed Central

    Gerber, Martina; Fischer, Andrea; Jagannathan, Vidhya; Drögemüller, Michaela; Drögemüller, Cord; Schmidt, Martin J.; Bernardino, Filipa; Manz, Eberhard; Matiasek, Kaspar; Rentmeister, Kai; Leeb, Tosso

    2015-01-01

    Dandy-Walker-like malformation (DWLM) is the result of aberrant brain development and mainly characterized by cerebellar hypoplasia. DWLM affected dogs display a non-progressive cerebellar ataxia. Several DWLM cases were recently observed in the Eurasier dog breed, which strongly suggested a monogenic autosomal recessive inheritance in this breed. We performed a genome-wide association study (GWAS) with 9 cases and 11 controls and found the best association of DWLM with markers on chromosome 1. Subsequent homozygosity mapping confirmed that all 9 cases were homozygous for a shared haplotype in this region, which delineated a critical interval of 3.35 Mb. We sequenced the genome of an affected Eurasier and compared it with the Boxer reference genome and 47 control genomes of dogs from other breeds. This analysis revealed 4 private non-synonymous variants in the critical interval of the affected Eurasier. We genotyped these variants in additional dogs and found perfect association for only one of these variants, a single base deletion in the VLDLR gene encoding the very low density lipoprotein receptor. This variant, VLDLR:c.1713delC is predicted to cause a frameshift and premature stop codon (p.W572Gfs*10). Variants in the VLDLR gene have been shown to cause congenital cerebellar ataxia and mental retardation in human patients and Vldlr knockout mice also display an ataxia phenotype. Our combined genetic data together with the functional knowledge on the VLDLR gene from other species thus strongly suggest that VLDLR:c.1713delC is indeed causing DWLM in Eurasier dogs. PMID:25668033

  5. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    USGS Publications Warehouse

    Funk, Christopher C.; Williams, A. Park

    2011-01-01

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E–140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

  6. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    USGS Publications Warehouse

    Williams, A. Park; Funk, Christopher C.

    2011-01-01

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E–140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

  7. Variation in foliar 15N abundance and the availability of soil nitrogen on Walker Branch Watershed

    SciTech Connect

    Garten Jr, Charles T

    1993-10-01

    Spatial patterns in natural {sup 15}N abundance ({sup o}{sup 15}N) in soil, soil solutions, and non-N{sub 2}-fixing plants were studied in the deciduous forest on Walker Branch Watershed near Oak Ridge, Tennessee. This study was undertaken to test the hypothesis that foliar {sup o}{sup 15}N values are related to the availability of inorganic nitrogen in mineral soil. Soils collected in or near valley bottoms on the watershed had higher levels of net nitrogen mineralization and net nitrification potential than those sampled from ridges and slopes. More positive foliar {sup o}{sup 15}N values occurred in valley bottoms, which, relative to other positions on the watershed, were characterized by greater availability of soil nitrogen and lower C-to-N ratios in the O{sub i}-horizon, in the surface mineral soil, and in autumn leaf fall. Although leaf nitrogen concentrations changed significantly over the course of the growing season, there was little seasonal variation in foliar {sup o}{sup 15}N values. A hypothesis about the relative importance of different sources of nitrogen to the forest and how nitrogen cycling varies with topography in this nitrogen-deficient ecosystem was derived, in part, from spatial patterns in natural {sup 15}N abundance. There appear to be two processes affecting the topographic patterns in foliar {sup 15}N abundance on this watershed: (1) greater uptake from isotopically heavy pools of inorganic soil nitrogen by plants in valley bottoms, and (2) uptake of isotopically light ammonium-N in atmospheric deposition by plants on ridges and slopes (where the availability of inorganic soil nitrogen to plant roots is more limited). Results from this study indicate that foliar {sup o}{sup 15}N values are positively correlated with net nitrification potential in surface soil.

  8. Variation in foliar [sup 15]N abundance and the availability of soil nitrogen on Walker Branch Watershed

    SciTech Connect

    Garten, C.T. Jr. )

    1993-10-01

    Spatial patterns in natural [sup 15]N abundance ([sigma][sup 15]N) in soil, soil solutions, and non-N[sub 2]-fixing plants were studied in the deciduous forest on Walker Branch Watershed near Oak Ridge, Tennessee. This study was undertaken to test the hypothesis that foliar [sigma][sup 15]N values are related to the availability of inorganic nitrogen in mineral soil. Soils collected in or near valley bottoms on the watershed had higher levels of net nitrogen mineralization and net nitrification potential than those sampled from ridges and slopes. More positive foliar [sigma][sup 15]N values occurred in valley bottoms, which, relative to other positions on the watershed, were characterized by greater availability of soil nitrogen and lower C-to-N ratios in the O[sub 1]-horizon, in the surface mineral soil, and in autumn leaf fall. Although leaf nitrogen concentrations changed significantly over the course of the growing season, there was little seasonal variation in foliar [sigma][sup 15]N values. A hypothesis about the relative importance of different sources of nitrogen to the forest and how nitrogen cycling varies with topography in this nitrogen-deficient ecosystem was derived, in part, from spatial patterns in natural [sup 15]N abundance. There appear to be two processes affecting the topographic patterns in foliar [sup 15]N abundance on this watershed: (1) greater uptake from isotopically heavy pools of inorganic soil nitrogen by plants in valley bottoms, and (2) uptake of isotopically light ammonium-N in atmospheric deposition by plants on ridges and slopes (where the availability of inorganic soil nitrogen to plant roots is more limited). Results from this study indicate that foliar [sigma][sup 15]N values are positively correlated with net nitrification potential in surface soil. 34 refs., 13 figs., 8 tabs.

  9. In-stream biotic control on nutrient biogeochemistry in a forested sheadwater tream, West Fork of Walker Branch

    SciTech Connect

    Roberts, Brian J; Mulholland, Patrick J

    2007-01-01

    A growing body of evidence demonstrates the importance of in-stream processing in regulating nutrient export, yet the influence of temporal variability in stream metabolism on net nutrient uptake has not been explicitly addressed. Streamwater DIN and SRP concentrations in Walker Branch, a first-order deciduous forest stream in eastern Tennessee, show a repeated pattern of annual maxima in summer and biannual minima in spring and autumn. Temporal variations in catchment hydrologic flowpaths result in lower winter and higher summer nutrient concentrations, but do not explain the spring and autumn nutrient minima. Ambient nutrient uptake rates were measured 2-3 times per week over an 18-mo period and compared to daily rates of gross primary production (GPP) and ecosystem respiration (ER) to examine the influence of in-stream biotic activity on nutrient export. GPP and ER rates explained 85% of the variation in net DIN retention with high net NO3- uptake (and lower net NH4+ release) rates occurring during spring and autumn and net DIN release in summer. Diel nutrient concentration patterns were examined several times throughout the year to determine the relative importance of autotrophic and heterotrophic activity on net nutrient uptake. High spring GPP corresponded to daily decreases in NO3- over the illuminated hours resulting in high diel NO3- amplitude which dampened as the canopy closed. GPP explained 91% of the variance in diel NO3- amplitude. In contrast, the autumn nutrient minima was largely explained by heterotrophic respiration since GPP remained low and little diel NO3- variation was observed during the autumn.

  10. Enhancement of photodynamic therapy due to hyperbaric hyperoxia: an experimental study of Walker 256 tumors in rats

    NASA Astrophysics Data System (ADS)

    Nicola, Jorge H.; Colussi, Valdir C.; Nicola, Ester M. D.; Metze, Konradin

    1997-05-01

    Photodynamic therapy (PDT), which is now an approved treatment for many types of cancers, is based on the simultaneous involvement of three factors, namely: tumor tissue retention of a specific photosensitizer; local illumination of the lesion with a visible light source and the occurrence of oxygen in the triplet state. Theoretically, a change in any one of these factors may be compensated by a change in the other two factors, leading to the same therapeutic result. In practice, this is not true, since we are dealing with living tissue, but we may expect to find an ideal combination of these three factors which may give the best clinical results. In this work we present experimental results of PDT under Hyperbaric hyperoxia (HBO) in tumor masses of the dorsal subcutaneous tissue of rats. These tumors were created by previous inoculation of 'Walker 256' neoplastic cells Hematoporphyrin Ester (HpE) was administered as the photosensitizer. The rats were pressurized at up to 3 atm with a 100 percent continuous oxygen ventilation environment in a specially designed hyperbaric chamber. The skin area above the tumor was photosensitized for 45 minutes with a 7 mw HeNe laser. Twenty four hours later, the tumor was removed for study. In all the animals treated with PDT/HBO histology revealed a very important reduction in the number of tumor cells as compared with the PDT controls in normal atmospheric condition, showing numerous apoptotic as well as necrotic cells at the border of the radiated area. The observed enhancement in the PDT for this situation is, of course, related to the extra oxygen in the circulatory system.

  11. A province-scale block model of Walker Lane and western Basin and Range crustal deformation constrained by GPS observations (Invited)

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Bormann, J.; Blewitt, G.; Kreemer, C.

    2013-12-01

    The Walker Lane in the western Great Basin of the western United States is an 800 km long and 100 km wide zone of active intracontinental transtension that absorbs ~10 mm/yr, about 20% of the Pacific/North America plate boundary relative motion. Lying west of the Sierra Nevada/Great Valley microplate (SNGV) and adjoining the Basin and Range Province to the east, deformation is predominantly shear strain overprinted with a minor component of extension. The Walker Lane responds with faulting, block rotations, structural step-overs, and has distinct and varying partitioned domains of shear and extension. Resolving these complex deformation patterns requires a long term observation strategy with a dense network of GPS stations (spacing ~20 km). The University of Nevada, Reno operates the 373 station Mobile Array of GPS for Nevada transtension (MAGNET) semi-continuous network that supplements coverage by other networks such as EarthScope's Plate Boundary Observatory, which alone has insufficient density to resolve the deformation patterns. Uniform processing of data from these GPS mega-networks provides a synoptic view and new insights into the kinematics and mechanics of Walker Lane tectonics. We present velocities for thousands of stations with time series between 3 to 17 years in duration aligned to our new GPS-based North America fixed reference frame NA12. The velocity field shows a rate budget across the southern Walker Lane of ~10 mm/yr, decreasing northward to ~7 mm/yr at the latitude of the Mohawk Valley and Pyramid Lake. We model the data with a new block model that estimates rotations and slip rates of known active faults between the Mojave Desert and northern Nevada and northeast California. The density of active faults in the region requires including a relatively large number of blocks in the model to accurately estimate deformation patterns. With 49 blocks, our the model captures structural detail not represented in previous province-scale models, and

  12. Recent crustal movements in the Sierra Nevada-Walker lane region of California-Nevada: Part i, rate and style of deformation

    USGS Publications Warehouse

    Slemmons, D.B.; Wormer, D.V.; Bell, E.J.; Silberman, M.L.

    1979-01-01

    This review of geological, seismological, geochronological and paleobotanical data is made to compare historic and geologic rates and styles of deformation of the Sierra Nevada and western Basin and Range Provinces. The main uplift of this region began about 17 m.y. ago, with slow uplift of the central Sierra Nevada summit region at rates estimated at about 0.012 mm/yr and of western Basin and Range Province at about 0.01 mm/yr. Many Mesozoic faults of the Foothills fault system were reactivated with normal slip in mid-Tertiary time and have continued to be active with slow slip rates. Sparse data indicate acceleration of rates of uplift and faulting during the Late Cenozoic. The Basin and Range faulting appears to have extended westward during this period with a reduction in width of the Sierra Nevada. The eastern boundary zone of the Sierra Nevada has an irregular en-echelon pattern of normal and right-oblique faults. The area between the Sierra Nevada and the Walker Lane is a complex zone of irregular patterns of ho??rst and graben blocks and conjugate normal-to right- and left-slip faults of NW and NE trend, respectively. The Walker Lane has at least five main strands near Walker Lake, with total right-slip separation estimated at 48 km. The NE-trending left-slip faults are much shorter than the Walker Lane fault zone and have maximum separations of no more than a few kilometers. Examples include the 1948 and 1966 fault zone northeast of Truckee, California, the Olinghouse fault (Part III) and possibly the almost 200-km-long Carson Lineament. Historic geologic evidence of faulting, seismologic evidence for focal mechanisms, geodetic measurements and strain measurements confirm continued regional uplift and tilting of the Sierra Nevada, with minor internal local faulting and deformation, smaller uplift of the western Basin and Range Province, conjugate focal mechanisms for faults of diverse orientations and types, and a NS to NE-SW compression axis (??1) and an

  13. The colonization of carrion by soldier fly, Ptecticus melanurus (Walker) (Diptera: Stratiomyidae) in a tropical forest in Malaysia: a new potential species for minimum PMI estimation.

    PubMed

    Azwandi, A; Omar, B

    2012-12-01

    This paper discusses the colonization of the stratiomyid species Ptecticus melanurus (Walker) (Diptera: Stratiomyidae) in monkey carrion and its potential for the determination of the minimum time since death (PMI). A study was conducted in a tropical forest at Bangi, Malaysia from 13 November 2009 to 8 June 2011. Twelve monkey carcasses (Macaca fascicularis Raffles) were used and divided in equal number into three different field trials. Adults of P. melanurus were first observed on monkey carrions on the second day the carcasses were placed in the field while their penultimate instar larvae were found in the wet soil under and beside carcass from day 8 to 31 days postmortem. PMID:23202610

  14. Assessing Methane Migration Mechanisms at Walker Ridge, Gulf of Mexico, via 3D Methane Hydrate Reservoir Modeling

    NASA Astrophysics Data System (ADS)

    Nole, M.; Daigle, H.; Mohanty, K. K.; Hillman, J. I. T.; Cook, A.

    2015-12-01

    We employ a 3D methane hydrate reservoir simulator to model marine methane hydrate systems. Our simulator couples highly nonlinear heat and mass transport equations and includes heterogeneous sedimentation, in-situ organic methanogenesis, and the influences of both pore size contrast and salt exclusion from the hydrate phase on solubility gradients. Using environmental parameters of Walker Ridge, Gulf of Mexico, we first simulate hydrate formation in and around a thin, dipping, planar sand stratum surrounded by clay lithology as it is buried to 295mbsf. With sufficient methane supplied by methanogenesis in the clays, a 200x sand-clay pore size contrast allows for a strong enough concentration gradient to significantly drop the concentration of hydrate in clays immediately surrounding a thin sand, a phenomenon observed in corresponding well log data. Building upon previous work, our simulations account for a depth-wise increase in sand-clay solubility contrast from about 1.6% near the seafloor to 8.6% at depth, progressively strengthening the diffusive flux of methane with time. An exponentially decaying methanogenesis input to the clay lithology decreases the methane supplied to clays surrounding the sand layer with time, further enhancing the sand-clay hydrate saturation contrast. Significant diffusive methane transport occurs in a clay interval of about 11m above the sand and 4m below it, matching well log observations. Clay-sand pore size contrast alone is not enough to create hydrate-free zones seen in logs, because the corresponding diffusive methane flux is slower than the rate at which methanogenesis supplies methane. Therefore, it is likely that additional mechanisms are at play, notably bound water activity reduction in clays. Three-dimensionality allows for inclusion of lithologic heterogeneities, which focus flow and allow for heterogeneity in locally dominant methane migration mechanisms. Incorporating recent 3D seismic data to inform the model

  15. Late quaternary slip-rate variations along the Warm Springs Valley fault system, northern Walker Lane, California-Nevada border

    USGS Publications Warehouse

    Gold, Ryan; dePolo, Craig; Briggs, Richard W.; Crone, Anthony

    2013-01-01

    The extent to which faults exhibit temporally varying slip rates has important consequences for models of fault mechanics and probabilistic seismic hazard. Here, we explore the temporal behavior of the dextral‐slip Warm Springs Valley fault system, which is part of a network of closely spaced (10–20 km) faults in the northern Walker Lane (California–Nevada border). We develop a late Quaternary slip record for the fault using Quaternary mapping and high‐resolution topographic data from airborne Light Distance and Ranging (LiDAR). The faulted Fort Sage alluvial fan (40.06° N, 119.99° W) is dextrally displaced 98+42/-43 m, and we estimate the age of the alluvial fan to be 41.4+10.0/-4.8 to 55.7±9.2  ka, based on a terrestrial cosmogenic 10Be depth profile and 36Cl analyses on basalt boulders, respectively. The displacement and age constraints for the fan yield a slip rate of 1.8 +0.8/-0.8 mm/yr to 2.4 +1.2/-1.1 mm/yr (2σ) along the northern Warm Springs Valley fault system for the past 41.4–55.7 ka. In contrast to this longer‐term slip rate, shorelines associated with the Sehoo highstand of Lake Lahontan (~15.8  ka) adjacent to the Fort Sage fan are dextrally faulted at most 3 m, which limits a maximum post‐15.8 ka slip rate to 0.2  mm/yr. These relations indicate that the post‐Lahontan slip rate on the fault is only about one‐tenth the longer‐term (41–56 ka) average slip rate. This apparent slip‐rate variation may be related to co‐dependent interaction with the nearby Honey Lake fault system, which shows evidence of an accelerated period of mid‐Holocene earthquakes.

  16. Integrated Kinematic Analysis of GPS and Fault Slip Data in the Eastern California Shear Zone, Walker Lane and Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Thatcher, W.

    2001-12-01

    The Sierra Nevada (SN) microplate moves roughly N50?W with respect to North America (NA), around an Euler pole that lies in the Pacific (PA) basin to the west and south. Its motion is indicative of processes governing the deformation of the Walker Lane and Eastern California Shear Zone, accommodating east to west expansion of the Basin and Range and approximately 25% of PA/NA dextral shear. To date, estimates for the location of the SN/NA pole obtained by GPS, VLBI and geologic data differ by at least 30 degrees [e.g. Argus and Gordon, 1996; Hearn and Humphreys, 1998]. The difference between these poles may, in part, be attributable to the type of data used in the analyses. The GPS determined velocity field potentially contains artifacts of the earthquake cycle such as recoverable elastic deformation preceded by slip at depth, fault creep, and viscoelastic relaxation following earthquakes on block bounding faults. We use Global Positioning System (GPS), fault strike and slip rate data to constrain the kinematics of the eastern boundary of the Sierra Nevada (SN) microplate, and western Basin and Range province of western North America. Data include previously published GPS measurements [Bennet et al., 1998; Thatcher et al., 1999; Gan et al., 2000; Svarc et al., submitted manuscript 2001], recently collected GPS data, and recently compiled fault maps of Nevada and California that include fault strike, slip sense and slip rate estimates. GPS velocities are refined with the Quasi Observation Combination Analysis algorithm of Dong et al. From these data we constrain the spatial variation in the rate and style of deformation throughout the region, and identify components of the deformation that are relevant to interaction of the PA/NA transform margin and Basin and Range extension. Using two-dimensional viscoelastic finite elements we derive kinematic models representative of the instantaneous (GPS) time scale, in preparation for future modeling of the longer term

  17. Present-Day Kinematics of Crustal Deformation of the Walker Lane and Central Nevada, Derived From GPS Data

    NASA Astrophysics Data System (ADS)

    Nyst, M. C.; Hammond, W. C.

    2002-12-01

    The Walker Lane (WL) is a zone of tectonic deformation located between the western edge of the Basin and Range province (BR) in Nevada and the Sierra Nevada in California. It extends from ~36o in California to ~41o latitude in western Nevada and eastern California. The WL is of great interest for the study of intra-plate deformation because it accommodates the transfer of NW directed motion of the Sierra Nevada block to roughly E-W extension in the eastern BR. In addition, by connecting the Eastern California Shear Zone (ECSZ) with more northern zones of dextral shear such as the Central Nevada Seismic Zone (CNSZ) the WL plays an important role in the accommodation of motion between the Pacific and North America plates. Previous studies of the present-day crustal deformation in this area focused on sub-regions of the WL. We study the whole WL and utilize a relatively dense GPS velocity set (of 121 stations with data from 1992 to 2002) to model crustal deformation. The GPS data set consists of the western Nevada data of Svarc et al. (JGR, 2002), the BR data of Thatcher et al. (Science, 1999) and the ECSZ data of Gan et al. (JGR, 2000). Principal strain rates derived from data subsets agree with those of previous studies: In the northern WL WNW-ESE extension averages ~24 nstrain/yr and NNE-SSW contraction averages ~9 nstrain/yr. Since the average fault trend is NNW, the resulting strain rates may be indicative for dextral transtensional slip. In the central WL WNW-ESE extension (~27 nstrain/yr) and NNE-SSW contraction (~11 nstrain/yr) together with the predominantly ENE trending faults suggest sinistral transtensional slip. In the southern WL ENE-WSW extension (~25 nstrain/yr), NNW-SSE contraction (~30 nstrain/yr) and NNW trending faults correspond to dextral slip. To determine the spatial variation of the crustal deformation field we solve for a self-consistent continuous velocity gradient field from which both strain and rotation rate fields are derived. In general

  18. Long-Term Data Reveal Patterns and Controls on Stream Water Chemistry in a Forested Stream: Walker Branch, Tennessee

    SciTech Connect

    Lutz, Brian D; Mulholland, Patrick J; Bernhardt, Emily

    2012-01-01

    We present 20 years of weekly stream water chemistry, hydrology, and climate data for the Walker Branch watershed in eastern Tennessee, USA. Since 1989, the watershed has experienced a similar to 1.08 degrees C increase in mean annual temperature, a similar to 20% decline in precipitation, and a similar to 30% increase in forest evapotranspiration rates. As a result, stream runoff has declined by similar to 34%. We evaluate long-term trends in stream water concentrations and fluxes for nine solutes and use wet deposition data to calculate approximate watershed input-output budgets. Dissolved constituents were classified as geochemical solutes (Ca2+, Mg2+, and SO42-) or nutrients (NH4+, NO3-, soluble reactive phosphorus [SRP], total soluble nitrogen [TSN], total soluble phosphorus [TSP], and dissolved organic carbon [DOC]). Geochemical solutes are predominantly controlled by discharge, and the long-term changes in catchment hydrology have led to significant trends in the concentrations and fluxes of these solutes. Further, the trends in geochemical solute concentrations indicate shifting soil flowpath contributions to streamflow generation through time, with deep groundwater having a greater proportional contribution in recent years. Despite dramatic changes in watershed runoff, there were no trends in inorganic nutrient concentrations (NH4+, NO3-, and SRP). While most nutrients entering the watershed are retained, stream fluxes of nutrient solutes have declined significantly as a result of decreasing runoff. Nutrient concentrations in the stream exhibit large seasonality controlled by in-stream biological uptake. Stream benthic communities are sensitive to hydrologic disturbance, and changes in the frequency or intensity of storm events through time can affect nutrient fluxes. Stream NO3- concentrations are also sensitive to drought, with concentrations decreasing (increasing) if conditions during the three years prior to the time of sampling were drier (wetter

  19. Immune and metabolic responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) larvae to an insect growth regulator, hexaflumuron.

    PubMed

    Mirhaghparast, Seyyedeh Kimia; Zibaee, Arash; Sendi, Jalal Jalali; Hoda, Hassan; Fazeli-Dinan, Mahmoud

    2015-11-01

    Efficient control of Chilo suppressalis Walker is always controversial due to highly economic damage, resistance to insecticides and environmental pollutions. So, combination of safe pest controls e.g. biocontrol agents and insect growth regulators seems to be promising via integrated pest management program. Bioassay of hexaflumuron on 4th larval instars revealed concentrations of 44.34, 179.74 and 474.94µg/ml as LC10-50 values. Numbers of total hemocytes, plasmatocytes and granulocytes as well as phenoloxidase activity increased in the different time intervals following treatment by hexaflumuron. Combined effects of hexaflumuron and Beauveria bassiana Vuillemin also increased hemocyte numbers and phenoloxidase activity at different time intervals using all concentrations. Activities of general esterases assayed by α- and β-naphtyl acetate and glutathione S-transferase using CDNB and DCNB increased 1-12h post-treatment. Activities of aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase and aldolase increased in the larvae treated by hexaflumuron. However enhanced activity of lactate dehydrogenase was only obtained by treating 180 and 470µg/ml concentrations of hexaflumuron. Activities of ACP and ALP were found to be higher than control for all time intervals even 1-12h post-treatment. The amounts of HDL and LDL increased in the highest concentrations of hexaflumuron after 12-24h of post-treatment. Amount of triglyceride was higher than that of control after 1 and 3h but it was lower in other time intervals. Amounts of glycogen and protein were lower than those of control for all time intervals except for 6 and 12h of post-treatment in case of protein. Results of the current study revealed negative effects of hexaflumuron on intermediary metabolism of Chilo suppressalis but it increased the number of hemocytes and activity of phenoloxidase which are responsible for spore removal from hemolymph. It can be concluded that hexaflumuron is

  20. Dandy-Walker Syndrome

    MedlinePlus

    ... The key features of this syndrome are an enlargement of the fourth ventricle (a small channel that ... early infancy, include slow motor development and progressive enlargement of the skull. In older children, symptoms of ...

  1. From precocious fame to mature obscurity: David Walker (1837-1917) MD, LRCSI, surgeon and naturalist to the Fox Arctic Expedition of 1857-59.

    PubMed

    Froggatt, Peter; Walker, Brian M

    2012-11-01

    The Belfast-born David Walker was the 19-year-old surgeon and naturalist on the epic Fox Arctic Expedition (1857-59) that established the fate of Sir John Franklin's unsuccessful (1845) search for the North-West Passage. On return the crew were fêted as heroes and decorated, and shared in a £5000 government bounty: Walker was also received by the Queen and (in Ireland) by the Lord Lieutenant, was honoured by the principal British and Irish natural history societies and his portrait was exhibited in the National Portrait Gallery, London. This paper describes his adventurous life, including the Fox Expedition, which from 1862 was spent abroad and included time in the Cariboo gold fields, service in the United States Army, practice in a notorious Californian frontier town and, in later life, the comparative quiet of general and occupational medical practice in Portland, Oregon. Once a household name, his death went unrecorded in the British and Irish medical and lay press.

  2. Clustering of velocities in a GPS network spanning the Sierra Nevada Block, the northern Walker Lane Belt, and the Central Nevada Seismic Belt, California-Nevada

    USGS Publications Warehouse

    Savage, James C.; Simpson, Robert W.

    2013-01-01

    The deformation across the Sierra Nevada Block, the Walker Lane Belt, and the Central Nevada Seismic Belt (CNSB) between 38.5°N and 40.5°N has been analyzed by clustering GPS velocities to identify coherent blocks. Cluster analysis determines the number of clusters required and assigns the GPS stations to the proper clusters. The clusters are shown on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. Four significant clusters are identified. Those clusters are strips separated by (from west to east) the Mohawk Valley-Genoa fault system, the Pyramid Lake-Wassuk fault system, and the Central Nevada Seismic Belt. The strain rates within the westernmost three clusters approximate simple right-lateral shear (~13 nstrain/a) across vertical planes roughly parallel to the cluster boundaries. Clustering does not recognize the longitudinal segmentation of the Walker Lane Belt into domains dominated by either northwesterly trending, right-lateral faults or northeasterly trending, left-lateral faults.

  3. Paleomagnetism of the Stanislaus Group, CA reveals revised stratigraphy, Walker Lane kinematics, and radio-isotopic constraints on C5 magnetic subchrons

    NASA Astrophysics Data System (ADS)

    Pluhar, C. J.; Wright, T. J.; Fischer, C. P.; Busby, C. J.

    2007-12-01

    Paleomagnetic study of the c.a. 9.2-10.3 Ma Stanislaus Group of intercalated latite (trachyandesite) lavas, ignimbrites and accessory sediments at three localities in Mono county California reveals: 1) a detailed, revised stratigraphy for the Stanislaus group, 2) kinematic constraints on the part of the Walker Lane since Stanislaus group emplacement, and 3) two age-constrained magnetic subchrons during chron C5N recorded by latites that had previously only been identified in seafloor magnetic anomalies. The revised stratigraphy results from detailed magnetostratigraphy combined with previous 40Ar/39Ar geochronologic constraints and stratigraphic studies. We find the lowermost unit, Table Mountain Latite, to consist of 23 or more individual lava flows falling into 5 magnetic (mostly normal) polarity zones, indicating that these rocks span at least 40,000 years of geologic time, based on the expected duration of magnetic reversals. Overlying Table Mountain Latite is the reversed-polarity Tollhouse Flat member of the Eureka Valley Tuff as described by previous authors. In the Sweetwater Roadless Area, thought to be proximal to the Stanislaus eruptive center, latite lava of both normal and reversed polarity are emplaced ontop of the Tollhouse Flat Member. Normal-polarity By Day member and normal-polarity Upper Member lie at very top of entire sequence. We find no field evidence for the normal polarity Dardanelle Formation latite flow at the top of the Group as had been previously reported by other workers. Instead, the Dardanelle formation member likely corresponds to the latite lava(s) between the By Day and Tollhouse Flat Eureka Valley Tuff. Based on previous 40Ar/39Ar dating, the two reversed zones within our magnetostratigraphy correspond to two of the proposed reversed subchrons/excursions during chron C5N. Direct dating of these reversed units may lead to future improvements to the magnetic polarity timescale for C5N. Our paleomagnetic results from three study

  4. The Conterminous United States Mineral Appraisal Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resources maps of the Walker Lake 1 degree x 2 degrees Quadrangle, California and Nevada

    USGS Publications Warehouse

    Stewart, John Harris; Chaffee, M.A.; Dohrenwend, J.C.; John, D.A.; Kistler, R.W.; Kleinhampl, F.J.; Menzie, W.D.; Plouff, Donald; Rowan, L.C.; Silberling, Norman J.

    1984-01-01

    The Walker Lake 1? by 2? quadrangle in eastern California and western Nevada was studied by an interdisciplinary research team to appraise its mineral resources. The appraisal is based on geological, geochemical, and geophysical field and laboratory investigations, the results of which are published as a folio of maps, figures, and tables, with accompanying discussions. This circular provides background information on the investigations and integrates the information presented in the folio. The selected bibliography lists selected references to the geology, geochemistry, geophysics, and mineral deposits of the Walker Lake 1? by 2? quadrangle.

  5. Mach's principle: Exact frame-dragging via gravitomagnetism in perturbed Friedmann-Robertson-Walker universes with K=({+-}1,0)

    SciTech Connect

    Schmid, Christoph

    2009-03-15

    We show that there is exact dragging of the axis directions of local inertial frames by a weighted average of the cosmological energy currents via gravitomagnetism for all linear perturbations of all Friedmann-Robertson-Walker (FRW) universes and of Einstein's static closed universe, and for all energy-momentum-stress tensors and in the presence of a cosmological constant. This includes FRW universes arbitrarily close to the Milne Universe and the de Sitter universe. Hence the postulate formulated by Ernst Mach about the physical cause for the time-evolution of inertial axes is shown to hold in general relativity for linear perturbations of FRW universes. - The time-evolution of local inertial axes (relative to given local fiducial axes) is given experimentally by the precession angular velocity {omega}-vector{sub gyro} of local gyroscopes, which in turn gives the operational definition of the gravitomagnetic field: B-vector{sub g}{identical_to}-2{omega}-vector{sub gyro}. The gravitomagnetic field is caused by energy currents J-vector{sub {epsilon}} via the momentum constraint, Einstein's G{sup 0-}circumflex{sub i-circumflex} equation, (-{delta}+{mu}{sup 2})A-vector{sub g}=-16{pi}G{sub N}J-vector{sub {epsilon}} with B-vector{sub g}=curl A-vector{sub g}. This equation is analogous to Ampere's law, but it holds for all time-dependent situations. {delta} is the de Rham-Hodge Laplacian, and {delta}=-curl curl for the vorticity sector in Riemannian 3-space. - In the solution for an open universe the 1/r{sup 2}-force of Ampere is replaced by a Yukawa force Y{sub {mu}}(r)=(-d/dr)[(1/R)exp(-{mu}r)], form-identical for FRW backgrounds with K=(-1,0). Here r is the measured geodesic distance from the gyroscope to the cosmological source, and 2{pi}R is the measured circumference of the sphere centered at the gyroscope and going through the source point. The scale of the exponential cutoff is the H-dot radius, where H is the Hubble rate, dot is the derivative with respect to

  6. Exploring Western and Eastern Pacific contributions to the 21st century Walker circulation intensification and teleconnected precipitation declines (Invited)

    NASA Astrophysics Data System (ADS)

    Funk, C. C.; Hoerling, M. P.; Hoell, A.; Verdin, J. P.; Robertson, F. R.; Alured, D.; Liebmann, B.

    2013-12-01

    presented. These results suggest that a substantial component of the recent Walker circulation intensification has been related to the IWPWS. The IWPWS warming extends from just north of Papua New Guinea to just west of Hawaii, and appears associated with SLP, wind and rainfall responses consistent with enhanced Indo-Pacific convection. These decomposition results are compared with a set of numerical simulation experiments based on the ECHAM5 and GFS models forced with characteristic IWP and EP SST for 1983-1996 and 1999-2012. The talk concludes with a tentative discussion of the decadal predictability associated with the IWPWS. Using both observed and model-simulated precipitation, we briefly explore potential IWPWS drought teleconnection regions in the Americas, Asia, Middle East, and Eastern Africa. Figure 1. Western Pacific and Eastern Pacific SST changes between 1999-2012 and 1983-1996. Figure 2. Western Pacific and Eastern Pacific GPCP precipitation changes between 1999-2012 and 1983-1996.

  7. Kinematics of Deformation in West-Central Walker Lane; Paleomagnetic Testing of Fault-Block Rotation and Doming Models, Eastern California and Western Nevada

    NASA Astrophysics Data System (ADS)

    Fredrickson, S. M.; Pluhar, C. J.; Carlson, C. W.

    2013-12-01

    Walker Lane is a broad (~100-200 km) zone of dextral shear located between the Sierra Nevada microplate and the Basin and Range Province. We consider Bodie Hills a part of the greater Walker Lane because it has experienced clockwise, vertical-axis rotation of crustal blocks due to dextral shear accommodation. This strain is variable, resulting in rotations ranging from ~10°-70° depending on location. The Miocene Eureka Valley Tuff (EVT) is an ideal strain marker, because it is a geologically instantaneous and laterally extensive unit. We use paleomagnetic analysis of ignimbrites to improve the resolution of strain domain boundaries as well as test for doming in Bodie Hills. EVT site mean directions were compared to reference directions of the Tollhouse Flat and By Day Members collected from the stable Sierra Nevada to determine magnitudes of vertical-axis rotation. Three new sites and three previously sampled sites define a high-rotation domain including Bridgeport Valley and the East Walker River Canyon with an average clockwise rotation of ~50°-60°. We define the eastern boundary of this high-rotation domain as coinciding with a mapped fault exhibiting 11.7°×7.9° rotation of the presumed footwall. Our data corroborates and improves on Carlson's (2012) kinematic model in which the greater Bodie Hills has rotated clockwise ~30° since EVT emplacement. Eutaxitic textures, dipping up to 90°, are gross indicators of true tilt, but are also influenced by original dips in some localities, complicating interpretations. John et al. (2012) describe a simple doming model of Bodie Hills since EVT emplacement, supported by the high elevation of outflow channels compared to source areas. Our paleomagnetic data does not support simple doming, suggesting that there is either no doming of Bodie Hills, or that vertical crustal displacements have occurred without large-scale folding. John et al. (2012) dated undifferentiated EVT in Bodie Hills at ~9.4 Ma; using

  8. Assessment of Prey Preference by the Generalist Predator, Mallada basalis (Walker), When Offered Two Species of Spider Mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor) on Papaya

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated potential prey preference of the generalist predator Mallada basalis (Walker) when offered two mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor), both important pests on papaya. Laboratory choice tests revealed that none of the three larval instars of M. basalis sho...

  9. Walker Gilmore: a stratified Woodland period occupation in eastern Nebraska. A report of the 1968 excavations. Final report 1968-83

    SciTech Connect

    Haas, D.R.

    1983-12-01

    Excavations at Walker Gilmore were designed to test the ill-defined concept of 'Sterns Creek culture' in the Central Plains subarea. Five Woodland period levels produced evidence for 48 tool classes, flora and fauna, and 762 features including structural remains. Level 1 is poorly recorded and relatively unknown. Levels 2 - 4 contain abundant evidence of subsistence, structure, and settlement. Broad spectrum hunting/gathering and horticulture are represented. Site structures includes food preparation areas associated with storage/drying facilities, hearths, and trash pits. Settlements appear to be semi-permanent, and involved in diverse procurement activities spanning two or more seasons. Level 2 habitation is radiocarbon dated between A.D. 1116 to 1255, which indicates contemporary development with Central Plains Tradition complexes, as well as Loseke Creek/Missouri Bluffs Woodland groups. Level 5 evidences settlement change as probable interaction with Central Plains Tradition complexes.

  10. The effects of the broad-specificity lipase inhibitor, tetrahydrolipstatin, on the growth, development and survival of the larvae of Epiphyas postvittana (Walker) (Tortricidae, Lepidoptera).

    PubMed

    Markwick, Ngaire P; Poulton, Joanne; McGhie, Tony K; Wohlers, Mark W; Christeller, John T

    2011-12-01

    The effects of the lipase inhibitor, tetrahydrolipstatin (THL), on neonate Epiphyas postvittana (Walker) (Lepidoptera, Tortricidae) larvae were investigated by feeding on control artificial diets (with and without 2% ethanol) and diets containing 2% ethanol and one of three concentrations of THL (0.011%, 0.037% and 0.11%). Small but significant reductions in growth rate, percent pupation and time to pupation were observed for larvae feeding on 2% ethanol control diet compared with standard control diet, but larger reductions in all parameters occurred with increasing THL concentration. Third instar larvae fed 0.011% THL in the diet had 40% of the midgut lipase activity in the relevant control larvae and showed up-regulation of gene expression of the gastric lipase-like family but not the pancreatic lipase-like family of midgut lipases. PMID:21910995

  11. Tracking discourse complexity preceding Alzheimer's disease diagnosis: a case study comparing the press conferences of Presidents Ronald Reagan and George Herbert Walker Bush.

    PubMed

    Berisha, Visar; Wang, Shuai; LaCross, Amy; Liss, Julie

    2015-01-01

    Changes in some lexical features of language have been associated with the onset and progression of Alzheimer's disease. Here we describe a method to extract key features from discourse transcripts, which we evaluated on non-scripted news conferences from President Ronald Reagan, who was diagnosed with Alzheimer's disease in 1994, and President George Herbert Walker Bush, who has no known diagnosis of Alzheimer's disease. Key word counts previously associated with cognitive decline in Alzheimer's disease were extracted and regression analyses were conducted. President Reagan showed a significant reduction in the number of unique words over time and a significant increase in conversational fillers and non-specific nouns over time. There was no significant trend in these features for President Bush.

  12. Severe intellectual disability, West syndrome, Dandy-Walker malformation, and syndactyly in a patient with partial tetrasomy 17q25.3.

    PubMed

    Hackmann, Karl; Stadler, Anja; Schallner, Jens; Franke, Kathlen; Gerlach, Eva-Maria; Schrock, Evelin; Rump, Andreas; Fauth, Christine; Tinschert, Sigrid; Oexle, Konrad

    2013-12-01

    We report on a de novo 0.5 Mb triplication (partial tetrasomy) of chromosome 17q25.3 in a 10-year-old girl with severe intellectual disability, infantile seizures (West syndrome), moderate hearing loss, Dandy-Walker malformation, microcephaly, craniofacial dysmorphism, striking cutaneous syndactyly (hands 3-4, feet 2-3), joint laxity, and short stature. The triplication resulted from the unusual combination of a terminal duplication at 17qter and a cryptic translocation of an extra copy of the same segment onto chromosome 10qter. The breakpoint at 17q25.3 was located within the FOXK2 gene. SNP chip analysis suggested that the rearrangement occurred during paternal meiosis involving both paternal chromosomes 17.

  13. An Automated Three-Dimensional Detection and Segmentation Method for Touching Cells by Integrating Concave Points Clustering and Random Walker Algorithm

    PubMed Central

    Gong, Hui; Chen, Shangbin; Zhang, Bin; Ding, Wenxiang; Luo, Qingming; Li, Anan

    2014-01-01

    Characterizing cytoarchitecture is crucial for understanding brain functions and neural diseases. In neuroanatomy, it is an important task to accurately extract cell populations' centroids and contours. Recent advances have permitted imaging at single cell resolution for an entire mouse brain using the Nissl staining method. However, it is difficult to precisely segment numerous cells, especially those cells touching each other. As presented herein, we have developed an automated three-dimensional detection and segmentation method applied to the Nissl staining data, with the following two key steps: 1) concave points clustering to determine the seed points of touching cells; and 2) random walker segmentation to obtain cell contours. Also, we have evaluated the performance of our proposed method with several mouse brain datasets, which were captured with the micro-optical sectioning tomography imaging system, and the datasets include closely touching cells. Comparing with traditional detection and segmentation methods, our approach shows promising detection accuracy and high robustness. PMID:25111442

  14. Tumor growth reduction is regulated at the gene level in Walker 256 tumor-bearing rats supplemented with fish oil rich in EPA and DHA.

    PubMed

    Borghetti, G; Yamazaki, R K; Coelho, I; Pequito, D C T; Schiessel, D L; Kryczyk, M; Mamus, R; Naliwaiko, K; Fernandes, L C

    2013-08-01

    We investigated the effect of fish oil (FO) supplementation on tumor growth, cyclooxygenase 2 (COX-2), peroxisome proliferator-activated receptor gamma (PPARγ), and RelA gene and protein expression in Walker 256 tumor-bearing rats. Male Wistar rats (70 days old) were fed with regular chow (group W) or chow supplemented with 1 g/kg body weight FO daily (group WFO) until they reached 100 days of age. Both groups were then inoculated with a suspension of Walker 256 ascitic tumor cells (3 × 10(7) cells/mL). After 14 days the rats were killed, total RNA was isolated from the tumor tissue, and relative mRNA expression was measured using the 2(-ΔΔCT) method. FO significantly decreased tumor growth (W=13.18 ± 1.58 vs WFO=5.40 ± 0.88 g, P<0.05). FO supplementation also resulted in a significant decrease in COX-2 (W=100.1 ± 1.62 vs WFO=59.39 ± 5.53, P<0.001) and PPARγ (W=100.4 ± 1.04 vs WFO=88.22 ± 1.46, P<0.05) protein expression. Relative mRNA expression was W=1.06 ± 0.022 vs WFO=0.31 ± 0.04 (P<0.001) for COX-2, W=1.08 ± 0.02 vs WFO=0.52 ± 0.08 (P<0.001) for PPARγ, and W=1.04 ± 0.02 vs WFO=0.82 ± 0.04 (P<0.05) for RelA. FO reduced tumor growth by attenuating inflammatory gene expression associated with carcinogenesis.

  15. Stromatolites provide a terrestrial record of a ~35ka warming event in Walker Lake, a remnant of the Pleistocene Lake Lahontan (Western Nevada, USA)

    NASA Astrophysics Data System (ADS)

    Juarez Rivera, M.; Agić, H.; Ward, L.; Kerrigan, Z.; Petryshyn, V. A.; Frantz, C. M.; Tripati, A.; Corsetti, F. A.; Spear, J. R.

    2014-12-01

    Walker Lake is a closed-basin remnant of the large Pleistocene glacial Lake Lahontan that has experienced drastic changes in water level. Carbonate structures, such as stromatolites, precipitated from the lake and were studied as potential sources for historical climate change. A 16.7 cm long stromatolite was collected from a paleoshoreline approximately 58 meters above the present Walker Lake surface elevation. Radiocarbon dating revealed that the stromatolite spans approximately 2,000 years of growth, from 35,540 to 33,580 Calibrated YBP (IntCal13). Distinct laminae were drilled along the growth axis, and the resulting powders were collected for clumped isotope analyses, which uses the amount of heavy CO2 "clumps" (13C-18O-16O, or ∆47) generated from the dissolution of carbonate in acid to measure the temperature of formation of a rock. Using this method, we tracked the change in lake temperature and δ18Ofluid during stromatolite formation. Our results show that the stromatolite experienced an overall increase in temperature and δ18Ofluid values during the course of accretion. The resulting data were input to a Rayleigh distillation model for water evaporation in order to estimate the magnitude of lake level and volume fluctuations. Our modeling results show that, during the course of stromatolite accretion, the lake experienced a volume decrease of ~5 Km3, corresponding to lake level fall of ~14 meters. This study shows that lacustrine material (such as stromatolites or other tufas) can potentially be used to reconstruct the timing and magnitude of terrestrial climate change during important transitions in Earth history.

  16. Style of deformation along the Death Valley-Furnace Creek fault zone and other faults in the southern Walker Lane, Nevada and California

    SciTech Connect

    Noller, J.S. ); Reheis, M.C. )

    1993-04-01

    Quaternary normal and right-lateral faults and associated lineaments in the southern part of the Walker Lane are anomalous with respect to the north-striking normal faults in most of the central Great Basin. The authors identify and characterize many faults and lineaments that were previously unmapped, with the exception of faults in the Death Valley-Furnace Creek fault zone (DVFCFZ) and some faults in and near the Nevada Test Site. Faults and associated lineaments in deposits of late Cenozoic age are distinguished on the basis of age of most recent activity and orientation, and are grouped into two domains. One domain is characterized by northwest-striking faults and lineaments and associated north-striking en echelon structures within the DVFCFZ and the Pahrump fault zone; the other domain is characterized by north- to northeast-striking faults and linearments within a broad region east of the DVFCFZ that narrows southward toward the Pahrump fault zone. Preliminary observations of faults and linearments suggest dominantly right-oblique slip in the first domain and dominantly dip-slip in the second domain. The DVFCFZ is a regional right-lateral strike-slip system that shows changes in style of deformation along strike. Numerous normal faults at the northern end of the DVFCFZ in northern fish Lake Valley and the Volcanic Hills form an extensional right step that links the DVFCFZ with northwest-striking right-lateral faults of the northern part of the Walker Lane. South of this extensional step, the DVFCFZ trends southeast along strike-slip faults from central Fish Lake Valley to the latitude of Furnace Creek. From Furnace Creek, the fault zone apparently steps left to the Pahrump fault zone in the area of Ash Meadows where a complex zone of folds and faults of diverse orientation suggest local compression. This stepover coincides with east-northeast-striking faults that appear to be an extension of the left-lateral Rock Valley fault zone.

  17. Numerical Simulations of Depressurization-Induced Gas Production from the Gulf of Mexico, the Blue and Orange Walker Ridge 313 and the Green Canyon 955 Hydrate Deposits

    NASA Astrophysics Data System (ADS)

    Myshakin, E. M.; Anderson, B. J.; Rose, K.; Boswell, R. M.

    2010-12-01

    In 2009, the U.S. Department of Energy, National Energy Technology Laboratory expedition in collaboration with the U.S. Geological Survey confirmed that gas hydrate occurs at high saturations within reservoir-quality sands in the Gulf of Mexico. A dataset of density and resistivity logs from the gas hydrate logging-while-drilling (LWD) expedition of the Joint Industry Project, Leg II were collected for the Walker Ridge 313 and Green Canyon 955 sites. The hydrate saturations were calculated from the resistivity logs using Archie’s Law with exponents of both n=1.5 and 2.5. From this interpretation and density log data vertical descriptions of hydrate saturation and porosity variability were developed to create geological models of the Blue and Orange Walker Ridge 313 and Green Canyon 955 deposits at different well interval locations. The set of seismic attenuation data from the pre-drill analysis and the LWD data provide approximate spatial-dimensional descriptions of the reservoir in the horizontal direction. Numerical simulations of gas production from the Gulf of Mexico hydrate reservoirs were conducted using the depressurization method at a constant bottomhole pressure. The results revealed that hydrate deposits can be easily destabilized due to their proximity to the base of hydrate stability. The predicted production rates display high (2.3-13.0 MMscf/day) values making the reservoirs potentially attractive targets for further exploration. The sustained high rates were maintained during first several years before the hydrate completely dissociated, releasing all of their stored methane. To evaluate longer production periods the spatial boundary conditions in the radial direction was increased. The results showed a broad development of secondary hydrate formation around a well at reservoir models with extended dimensions. The reasons of hydrate reformation occurrence are discussed. The obtained data emphasize the importance of the evaluation of reservoir

  18. High-Precision Locations and the Stress Field from Instrumental Seismicity, Moment Tensors, and Short-Period Mechanisms through the Mina Deflection, Central Walker Lane

    NASA Astrophysics Data System (ADS)

    Ruhl, C. J.; Smith, K. D.

    2012-12-01

    The Mina Deflection (MD) region of the central Walker Lane of eastern California and western Nevada, is a complex zone of northeast-trending normal, and primarily left-lateral strike-slip to oblique-slip faulting that separates the Southern Walker Lane (SWL) from a series of east-tilted normal fault blocks in the Central Walker Lane (CWL) (Faulds and Henry, 2008; Surpless, 2008). The MD accommodates the transfer of right-lateral strike-slip motion from northwest-striking faults in the SWL to a series of left-stepping northwest-striking right-lateral strike-slip faults in the CWL, east of the Wassuk Range near Hawthorne, NV. The ~50 km wide ~80 km long right-step is a distinct transition in regional physiography that has been attributed to strain accommodation through pre-Cenozoic lithospheric structures. Several slip transfer mechanisms have been proposed within the MD, from clockwise rotation of high-angle fault blocks (Wesnousky, 2005), to low-angle displacement within the Silver Peak-Lone Mountain complex (Oldow et al., 2001), and curved fault arrays associated with localized basins and tectonic depressions (Ferranti et al., 2009). The region has been a regular source of M4+ events, the most recent being an extended sequence that included twenty-seven M 3.5+ earthquakes (largest event M 4.6) south of Hawthorne in 2011. These earthquakes (< 5 km depth) define shallow W-dipping (dip ~56°) and NW-dipping (dip ~70°) normal faulting constrained by moment tensor (MT) solutions and earthquake relocations. Temporary stations deployed in the source area provide good control. A distributed sequence in 2004, between Queen Valley and Mono Lake, primarily associated with the Huntoon Valley fault, included three M 5+ left-lateral strike-slip faulting events. A 1997 sequence in northern Fish Lake Valley (east of the White Mountains), with mainshock Mw 5.3 (Ichinose et al., 2003), also showed high-angle northeast-striking left-lateral strike-slip motion. Historical events

  19. Surface faulting and paleoseismic history of the 1932 Cedar Mountain earthquake area, west-central Nevada, and implications for modern tectonics of the Walker Lane

    USGS Publications Warehouse

    Bell, J.W.; DePolo, C.M.; Ramelli, A.R.; Sarna-Wojcicki, A. M.; Meyer, C.E.

    1999-01-01

    The 1932 Cedar Mountain earthquake (Ms 7.2) was one of the largest historical events in the Walker Lane region of western Nevada, and it produced a complicated strike-slip rupture pattern on multiple Quaternary faults distributed through three valleys. Primary, right-lateral surface ruptures occurred on north-striking faults in Monte Cristo Valley; small-scale lateral and normal offsets occurred in Stewart Valley; and secondary, normal faulting occurred on north-northeast-striking faults in the Gabbs Valley epicentral region. A reexamination of the surface ruptures provides new displacement and fault-zone data: maximum cumulative offset is estimated to be 2.7 m, and newly recognized faults extend the maximum width and end-to-end length of the rupture zone to 17 and 75 km, respectively. A detailed Quaternary allostratigraphic chronology based on regional alluvialgeomorphic relationships, tephrochronology, and radiocarbon dating provides a framework for interpreting the paleoseismic history of the fault zone. A late Wisconsinan alluvial-fan and piedmont unit containing a 32-36 ka tephra layer is a key stratigraphic datum for paleoseismic measurements. Exploratory trenching and radiocarbon dating of tectonic stratigraphy provide the first estimates for timing of late Quaternary faulting along the Cedar Mountain fault zone. Three trenches display evidence for six faulting events, including that in 1932, during the past 32-36 ka. Radiocarbon dating of organic soils interstratified with tectonically ponded silts establishes best-fit ages of the pre-1932 events at 4, 5,12,15, and 18 ka, each with ??2 ka uncertainties. On the basis of an estimated cumulative net slip of 6-12 m for the six faulting events, minimum and maximum late Quaternary slip rates are 0.2 and 0.7 mm/yr, respectively, and the preferred rate is 0.4-0.5 mm/yr. The average recurrence (interseismic) interval is 3600 yr. The relatively uniform thickness of the ponded deposits suggests that similar

  20. Different Phenotypes of Walker-Like A Box Mutants of ParA Homolog IncC of Broad-Host-Range IncP Plasmids

    PubMed Central

    Siddique, Azeem; Figurski, David H.

    2012-01-01

    The promiscuous IncPα plasmids RK2 and R995 encode a broad-host-range partition system, whose essential components include the incC and korB genes and a DNA site (OB) to which the korB product binds. IncC2, the smaller of the two incC products, is sufficient for stabilization of R995ΔincC. It is a member of the type Ia ParA family of partition ATPases. To better understand the role of ATP in partition, we constructed three alanine-substitution mutants of IncC2. Each mutation changed a different residue of the Walker-like ATP-binding and hydrolysis motif, including a lysine (K10) conserved solely among members of the ParA and MinD families. All three IncC2 mutants were defective in plasmid partition, but they differed from one another in other respects. The IncC2 T16A mutant, predicted to be defective in Mg2+ coordination, was severely impaired in all activities tested. IncC2 K10A, predicted to be defective in ATP hydrolysis, mediated enhanced incompatibility with R995 derivatives. IncC2 K15A, predicted to be defective in ATP binding, exhibited two distinct incompatibility properties depending on the genotype of the target plasmid. When in trans to plasmids carrying a complementable incC deletion, IncC2 K15A caused dramatic plasmid loss, even at low levels of expression. In trans to wild-type R995 or to R995ΔincC carrying a functional P1 partition system, IncC2 K15A-mediated incompatibility was significantly less than that caused by wild-type IncC2. All three Walker-like A box mutants were also defective for the host toxicity that normally results from co-overexpression of incC and korB. The phenotypes of the mutants support a model in which nucleotide hydrolysis is required for separation of paired plasmid complexes and possible interaction with a host factor. PMID:22579980

  1. Numerical simulations of depressurization-induced gas production from gas hydrate reservoirs at the Walker Ridge 312 site, northern Gulf of Mexico

    SciTech Connect

    Myshakin, Evgeniy M.; Gaddipati, Manohar; Rose, Kelly; Anderson, Brian J.

    2012-06-01

    In 2009, the Gulf of Mexico (GOM) Gas Hydrates Joint-Industry-Project (JIP) Leg II drilling program confirmed that gas hydrate occurs at high saturations within reservoir-quality sands in the GOM. A comprehensive logging-while-drilling dataset was collected from seven wells at three sites, including two wells at the Walker Ridge 313 site. By constraining the saturations and thicknesses of hydrate-bearing sands using logging-while-drilling data, two-dimensional (2D), cylindrical, r-z and three-dimensional (3D) reservoir models were simulated. The gas hydrate occurrences inferred from seismic analysis are used to delineate the areal extent of the 3D reservoir models. Numerical simulations of gas production from the Walker Ridge reservoirs were conducted using the depressurization method at a constant bottomhole pressure. Results of these simulations indicate that these hydrate deposits are readily produced, owing to high intrinsic reservoir-quality and their proximity to the base of hydrate stability. The elevated in situ reservoir temperatures contribute to high (5–40 MMscf/day) predicted production rates. The production rates obtained from the 2D and 3D models are in close agreement. To evaluate the effect of spatial dimensions, the 2D reservoir domains were simulated at two outer radii. The results showed increased potential for formation of secondary hydrate and appearance of lag time for production rates as reservoir size increases. Similar phenomena were observed in the 3D reservoir models. The results also suggest that interbedded gas hydrate accumulations might be preferable targets for gas production in comparison with massive deposits. Hydrate in such accumulations can be readily dissociated due to heat supply from surrounding hydrate-free zones. Special cases were considered to evaluate the effect of overburden and underburden permeability on production. The obtained data show that production can be significantly degraded in comparison with a case using

  2. Isolation and identification of two novel attractant compounds from Chinese cockroach (Eupolyphaga sinensis Walker) by combination of HSCCC, NMR and CD techniques.

    PubMed

    Jiang, Wei; Wu, Xiaodan; Wu, Bin

    2013-01-01

    High-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hextane-ethyl acetate-methanol-water (1.5:1:1.5:1, v/v/v/v) was applied to the isolation and purification of attractants from Chinese cockroach, Eupolyphaga sinensis Walker. Two new attractants with attractant activity towards the male insects were obtained from the extract sample in a one-step separation. Their purities were determined by HPLC. Subsequent MS, NMR and CD analyses have led to the characterization of (R)-3-ethyl-6,8-dihydroxy-7-methyl-3,4-dihydroisochromen-1-one (1) and (R)-6,8-dihydroxy-3,7-dimethyl-3,4-dihydroisochromen-1-one (2), two novel isocumarin type attractants. Based on these results, it is concluded that HSCCC is a viable separation method option for purifying insect attractants, while effectively maintaining the attracting activity of the isolates. This is the first attempt to apply counter-current chromatography technique to separate attractants from Chinese cockroach.

  3. Novel SIL1 nonstop mutation in a Chinese consanguineous family with Marinesco-Sjögren syndrome and Dandy-Walker syndrome.

    PubMed

    Gai, Nan; Jiang, Chen; Zou, Yong-Yi; Zheng, Yu; Liang, De-Sheng; Wu, Ling-Qian

    2016-07-01

    Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive disorder, which is characterized by congenital cataracts, cerebellar ataxia, progressive muscle weakness, and delayed psychomotor development. SIL1, which is located at 5q31.2, is the only gene known to cause MSS. Dandy-Walker syndrome (DWS) is defined by hypoplasia, upward rotation of the cerebellar vermis, and cystic dilation of the fourth ventricle; however, its genetic pathogeny remains unclear. Here, we report a Chinese consanguineous family with MSS and DWS. Whole exome sequencing identified a novel nonstop mutation in SIL1. Sanger sequencing revealed that the mutation was segregated in this family according to a recessive mode of inheritance. We found that the mutation changed a stop codon (TGA) to an arginine codon (CGA), and no in-frame termination codon in the 3' untranslated region (UTR) of SIL1 could be found. The mRNA levels of SIL1 were decreased by 56.6% and 37.5% in immortalized lymphoblasts of the patients respectively; the protein levels of SIL1 were substantially decreased. This case study is the first report on Chinese MSS patients, MSS complicated by DWS, and a nonstop mutation in SIL1. Our findings imply the pathogenetic association between DWS and MSS.

  4. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-brane, late-time cosmic acceleration, and the cosmic coincidence.

    PubMed

    Doolin, Ciaran; Neupane, Ishwaree P

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence--the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, M(P)(2) = ρ(b)/|Λ(5)|, where M(P) is the effective (normalized) Planck mass, Λ(5) is the five-dimensional cosmological constant, and ρ(b) is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρ(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8πM(P)(2))(-1) is satisfied when the ratio V/ρ ≳ O(10(2)) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations.

  5. Novel SIL1 nonstop mutation in a Chinese consanguineous family with Marinesco-Sjögren syndrome and Dandy-Walker syndrome.

    PubMed

    Gai, Nan; Jiang, Chen; Zou, Yong-Yi; Zheng, Yu; Liang, De-Sheng; Wu, Ling-Qian

    2016-07-01

    Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive disorder, which is characterized by congenital cataracts, cerebellar ataxia, progressive muscle weakness, and delayed psychomotor development. SIL1, which is located at 5q31.2, is the only gene known to cause MSS. Dandy-Walker syndrome (DWS) is defined by hypoplasia, upward rotation of the cerebellar vermis, and cystic dilation of the fourth ventricle; however, its genetic pathogeny remains unclear. Here, we report a Chinese consanguineous family with MSS and DWS. Whole exome sequencing identified a novel nonstop mutation in SIL1. Sanger sequencing revealed that the mutation was segregated in this family according to a recessive mode of inheritance. We found that the mutation changed a stop codon (TGA) to an arginine codon (CGA), and no in-frame termination codon in the 3' untranslated region (UTR) of SIL1 could be found. The mRNA levels of SIL1 were decreased by 56.6% and 37.5% in immortalized lymphoblasts of the patients respectively; the protein levels of SIL1 were substantially decreased. This case study is the first report on Chinese MSS patients, MSS complicated by DWS, and a nonstop mutation in SIL1. Our findings imply the pathogenetic association between DWS and MSS. PMID:27106665

  6. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-brane, late-time cosmic acceleration, and the cosmic coincidence.

    PubMed

    Doolin, Ciaran; Neupane, Ishwaree P

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence--the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, M(P)(2) = ρ(b)/|Λ(5)|, where M(P) is the effective (normalized) Planck mass, Λ(5) is the five-dimensional cosmological constant, and ρ(b) is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρ(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8πM(P)(2))(-1) is satisfied when the ratio V/ρ ≳ O(10(2)) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations. PMID:25166976

  7. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-Brane, Late-Time Cosmic Acceleration, and the Cosmic Coincidence

    NASA Astrophysics Data System (ADS)

    Doolin, Ciaran; Neupane, Ishwaree P.

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence—the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, MP2=ρb/|Λ5|, where MP is the effective (normalized) Planck mass, Λ5 is the five-dimensional cosmological constant, and ρb is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρb is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant GN=(8πMP2)-1 is satisfied when the ratio V/ρ≳O(102) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations.

  8. High K volcanism in the Sierra Nevada: A signal for the initiation of Walker Lane Faulting, and range uplift, not lithosphere delamination

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.; Busby, C. J.

    2007-12-01

    K2O contents have long been recognized as a potential indicator of tectonic processes, and based upon models developed for the Andes (Kay and Kay, 1993) and Tibet (Turner et al., 1996), high-K volcanism has been related to lithosphere delamination, by partial melting of a K-metasomatized lower crust or upper mantle (Feldstein and Lange, 1999; Manley et al., 2000). However, new data from the central Sierra Nevada cast doubt on this K2O-delamination link. Instead, high-K volcanism is better explained as low degree partial melts (F), where low F magmas are preferentially erupted over thick crust, under conditions of high tensile stress. In the central Sierra, a high tensile stress regime was imposed at the onset of Walker Lane transtension, at the eastern edge of the Basin and Range province. We surmise that high K volcanism is similarly controlled by the onset of tensile stresses throughout the Sierra, recording the initial phase of Sierra Nevada uplift. These conclusions stem from several observations. First, K2O contents are highly correlated with Th (R=0.82), Ba (R=0.83), U (R=0.85), Rb (R=0.88) and Pb (R=0.83), and other highly incompatible elements, suggesting a general enrichment mechanism, such as low degree partial melitng. Second, volcanic rocks with the highest K have the highest La/Nb and the lowest 143Nd/144Nd, indicative of a mantle lithosphere source - inconsistent with delamination. Third, maximum K contents increase from north (near Lassen) to south, following in increase in crustal thickness and the (87Sr/86Sr) i of basement granitoids, suggestive of a crustal control on volcanism. Finally, field evidence in the central Sierra shows that the pulse of high K2O volcanism there was synchronous with the development of a pull-apart, along a series of right-stepping dextral transtensional faults, at the onset of Walker Lane faulting. Partial melting calculations verify that primitive magma compositions from Lassen to the southern Sierra, can all be

  9. Tradeoffs between impact loading rate, vertical impulse and effective mass for walkers and heel strike runners wearing footwear of varying stiffness.

    PubMed

    Addison, Brian J; Lieberman, Daniel E

    2015-05-01

    Humans experience repetitive impact forces beneath the heel during walking and heel strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse-momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and heel strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F(2,54)=52.0, p=2.6E-13; running: F(2,54)=25.2, p=1.8E-8) and effective mass (walking: F(2,54)=12.1, p=4.6E-5; running: F(2,54)=15.5, p=4.7E-6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r=-0.88, p<0.0001; running: r=-0.78, p<0.0001) and between impact loading rate and effective mass (walking: r=-0.88, p<0.0001; running: r=-0.82, p<0.0001). The tradeoff relationships documented here raise questions about how and in what ways the stiffness of footwear heels influence injury risk during human walking and running.

  10. Uncaria tomentosa Exerts Extensive Anti-Neoplastic Effects against the Walker-256 Tumour by Modulating Oxidative Stress and Not by Alkaloid Activity

    PubMed Central

    Dreifuss, Arturo Alejandro; Bastos-Pereira, Amanda Leite; Fabossi, Isabella Aviles; Lívero, Francislaine Aparecida dos Reis; Stolf, Aline Maria; Alves de Souza, Carlos Eduardo; Gomes, Liana de Oliveira; Constantin, Rodrigo Polimeni; Furman, Aline Emmer Ferreira; Strapasson, Regiane Lauriano Batista; Teixeira, Simone; Zampronio, Aleksander Roberto; Muscará, Marcelo Nicolás; Stefanello, Maria Elida Alves; Acco, Alexandra

    2013-01-01

    This study aimed to compare the anti-neoplastic effects of an Uncaria tomentosa (UT) brute hydroethanolic (BHE) extract with those of two fractions derived from it. These fractions are choroformic (CHCl3) and n-butanolic (BuOH), rich in pentacyclic oxindole alkaloids (POA) and antioxidant substances, respectively. The cancer model was the subcutaneous inoculation of Walker-256 tumour cells in the pelvic limb of male Wistar rat. Subsequently to the inoculation, gavage with BHE extract (50 mg.kg−1) or its fractions (as per the yield of the fractioning process) or vehicle (Control) was performed during 14 days. Baseline values, corresponding to individuals without tumour or treatment with UT, were also included. After treatment, tumour volume and mass, plasma biochemistry, oxidative stress in liver and tumour, TNF-α level in liver and tumour homogenates, and survival rates were analysed. Both the BHE extract and its BuOH fraction successfully reduced tumour weight and volume, and modulated anti-oxidant systems. The hepatic TNF-α level indicated a greater effect from the BHE extract as compared to its BuOH fraction. Importantly, both the BHE extract and its BuOH fraction increased the survival time of the tumour-bearing animals. Inversely, the CHCl3 fraction was ineffective. These data represent an in vivo demonstration of the importance of the modulation of oxidative stress as part of the anti-neoplastic activity of UT, as well as constitute evidence of the lack of activity of isolated POAs in the primary tumour of this tumour lineage. These effects are possibly resulting from a synergic combination of substances, most of them with antioxidant properties. PMID:23408945

  11. Uncaria tomentosa exerts extensive anti-neoplastic effects against the Walker-256 tumour by modulating oxidative stress and not by alkaloid activity.

    PubMed

    Dreifuss, Arturo Alejandro; Bastos-Pereira, Amanda Leite; Fabossi, Isabella Aviles; Lívero, Francislaine Aparecida Dos Reis; Stolf, Aline Maria; Alves de Souza, Carlos Eduardo; Gomes, Liana de Oliveira; Constantin, Rodrigo Polimeni; Furman, Aline Emmer Ferreira; Strapasson, Regiane Lauriano Batista; Teixeira, Simone; Zampronio, Aleksander Roberto; Muscará, Marcelo Nicolás; Stefanello, Maria Elida Alves; Acco, Alexandra

    2013-01-01

    This study aimed to compare the anti-neoplastic effects of an Uncaria tomentosa (UT) brute hydroethanolic (BHE) extract with those of two fractions derived from it. These fractions are choroformic (CHCl3) and n-butanolic (BuOH), rich in pentacyclic oxindole alkaloids (POA) and antioxidant substances, respectively. The cancer model was the subcutaneous inoculation of Walker-256 tumour cells in the pelvic limb of male Wistar rat. Subsequently to the inoculation, gavage with BHE extract (50 mg.kg(-1)) or its fractions (as per the yield of the fractioning process) or vehicle (Control) was performed during 14 days. Baseline values, corresponding to individuals without tumour or treatment with UT, were also included. After treatment, tumour volume and mass, plasma biochemistry, oxidative stress in liver and tumour, TNF-α level in liver and tumour homogenates, and survival rates were analysed. Both the BHE extract and its BuOH fraction successfully reduced tumour weight and volume, and modulated anti-oxidant systems. The hepatic TNF-α level indicated a greater effect from the BHE extract as compared to its BuOH fraction. Importantly, both the BHE extract and its BuOH fraction increased the survival time of the tumour-bearing animals. Inversely, the CHCl3 fraction was ineffective. These data represent an in vivo demonstration of the importance of the modulation of oxidative stress as part of the anti-neoplastic activity of UT, as well as constitute evidence of the lack of activity of isolated POAs in the primary tumour of this tumour lineage. These effects are possibly resulting from a synergic combination of substances, most of them with antioxidant properties.

  12. Walker 256 tumour cells increase substance P immunoreactivity locally and modify the properties of the blood-brain barrier during extravasation and brain invasion.

    PubMed

    Lewis, Kate M; Harford-Wright, Elizabeth; Vink, Robert; Nimmo, Alan J; Ghabriel, Mounir N

    2013-01-01

    It is not yet known how tumour cells traverse the blood-brain barrier (BBB) to form brain metastases. Substance P (SP) release is a key component of neurogenic inflammation which has been recently shown to increase the permeability of the BBB following CNS insults, making it a possible candidate as a mediator of tumour cell extravasation into the brain. This study investigated the properties of the BBB in the early stages of tumour cell invasion into the brain, and the possible involvement of SP. Male Wistar rats were injected with Walker 256 breast carcinoma cells via the internal carotid artery and euthanised at 1, 3, 6 and 9 days post tumour inoculation. Culture medium-injected animals served as controls at 1 and 9 days. Evidence of tumour cell extravasation across the BBB was first observed at 3 days post-inoculation, which corresponded with significantly increased albumin (p < 0.05) and SP immunoreactivity (p < 0.01) and significantly reduced endothelial barrier antigen labelling of microvessels when compared to culture medium control animals (p < 0.001). By day 9 after tumour cell inoculation, 100 % of animals developed large intracranial neoplasms that had significantly increased albumin in the peri-tumoral area (p < 0.001). The increased SP immunoreactivity and altered BBB properties at 3 days post-inoculation that coincided with early tumour invasion may be indicative of a mechanism for tumour cell extravasation into the brain. Thus, extravasation of tumour cells into the brain to form cerebral metastases may be a SP-mediated process.

  13. Transcriptomics and Identification of the Chemoreceptor Superfamily of the Pupal Parasitoid of the Oriental Fruit Fly, Spalangia endius Walker (Hymenoptera: Pteromalidae)

    PubMed Central

    Zhang, Yuping; Zheng, Yuan; Li, Dunsong; Fan, Yilin

    2014-01-01

    Background The oriental fruit fly, Bactrocera dorsalis Hendel, causes serious losses to fruit production and is one of the most economically important pests in many countries, including China, Spalangia endius Walker is a pupal parasitoid of various dipteran hosts, and may be considered a potentially important ectoparasitic pupal parasitoid of B. dorsalis. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its interaction with this host. Analysis of the S. endius transcriptome is essential to extend the resources of genetic information on this species and, to support studies on S. endius on the host B. dorsalis. Methodology/Principal Findings We performed de novo assembly RNA-seq of S. endius. We obtained nearly 10 Gbp of data using a HiSeq platform, and 36319 high-quality transcripts using Trinity software. A total of 22443 (61.79%) unigenes were aligned to homologous sequences in the jewel wasp and honeybee (Apis florae) protein set from public databases. A total of 10037 protein domains were identified in 7892 S. endius transcripts using HMMER3 software. We identified expression of six gustatory receptor and 21 odorant receptor genes in the sample, with only one gene having a high expression level in each family. The other genes had a low expression level, including two genes regulated by splicing. This result may be due to the wasps being kept under laboratory conditions. Additionally, a total of 3727 SSR markers were predicted, which could facilitate the identification of polymorphisms and functional genes within wasp populations. Conclusion/Significance This transcriptome greatly improves our genetic understanding of S. endius and provides a large number of gene sequences for further study. PMID:24505315

  14. Mutations in the O-mannosyltransferase gene POMT1 give rise to the severe neuronal migration disorder Walker-Warburg syndrome.

    PubMed

    Beltrán-Valero de Bernabé, Daniel; Currier, Sophie; Steinbrecher, Alice; Celli, Jacopo; van Beusekom, Ellen; van der Zwaag, Bert; Kayserili, Hülya; Merlini, Luciano; Chitayat, David; Dobyns, William B; Cormand, Bru; Lehesjoki, Ana-Elina; Cruces, Jesús; Voit, Thomas; Walsh, Christopher A; van Bokhoven, Hans; Brunner, Han G

    2002-11-01

    Walker-Warburg syndrome (WWS) is an autosomal recessive developmental disorder characterized by congenital muscular dystrophy and complex brain and eye abnormalities. A similar combination of symptoms is presented by two other human diseases, muscle-eye-brain disease (MEB) and Fukuyama congenital muscular dystrophy (FCMD). Although the genes underlying FCMD (Fukutin) and MEB (POMGnT1) have been cloned, loci for WWS have remained elusive. The protein products of POMGnT1 and Fukutin have both been implicated in protein glycosylation. To unravel the genetic basis of WWS, we first performed a genomewide linkage analysis in 10 consanguineous families with WWS. The results indicated the existence of at least three WWS loci. Subsequently, we adopted a candidate-gene approach in combination with homozygosity mapping in 15 consanguineous families with WWS. Candidate genes were selected on the basis of the role of the FCMD and MEB genes. Since POMGnT1 encodes an O-mannoside N-acetylglucosaminyltransferase, we analyzed the possible implication of O-mannosyl glycan synthesis in WWS. Analysis of the locus for O-mannosyltransferase 1 (POMT1) revealed homozygosity in 5 of 15 families. Sequencing of the POMT1 gene revealed mutations in 6 of the 30 unrelated patients with WWS. Of the five mutations identified, two are nonsense mutations, two are frameshift mutations, and one is a missense mutation. Immunohistochemical analysis of muscle from patients with POMT1 mutations corroborated the O-mannosylation defect, as judged by the absence of glycosylation of alpha-dystroglycan. The implication of O-mannosylation in MEB and WWS suggests new lines of study in understanding the molecular basis of neuronal migration. PMID:12369018

  15. Tradeoffs between impact loading rate, vertical impulse and effective mass for walkers and heel strike runners wearing footwear of varying stiffness.

    PubMed

    Addison, Brian J; Lieberman, Daniel E

    2015-05-01

    Humans experience repetitive impact forces beneath the heel during walking and heel strike running that cause impact peaks characterized by high rates and magnitudes of loading. Impact peaks are caused by the exchange of momentum between the ground and a portion of the body that comes to a full stop (the effective mass) during the period of the impact peak. A number of factors can influence this exchange of momentum, including footwear stiffness. This study presents and tests an impulse-momentum model of impact mechanics which predicts that effective mass and vertical impulse is greater in walkers and heel strike runners wearing less stiff footwear. The model also predicts a tradeoff between impact loading rate and effective mass, and between impact loading rate and vertical impulse among individuals wearing footwear of varying stiffness. We tested this model using 19 human subjects walking and running in minimal footwear and in two experimental footpads. Subjects walked and ran on an instrumented treadmill and 3D kinematic data were collected. As predicted, both vertical impulse (walking: F(2,54)=52.0, p=2.6E-13; running: F(2,54)=25.2, p=1.8E-8) and effective mass (walking: F(2,54)=12.1, p=4.6E-5; running: F(2,54)=15.5, p=4.7E-6) increase in less stiff footwear. In addition, there is a significant inverse relationship between impact loading rate and vertical impulse (walking: r=-0.88, p<0.0001; running: r=-0.78, p<0.0001) and between impact loading rate and effective mass (walking: r=-0.88, p<0.0001; running: r=-0.82, p<0.0001). The tradeoff relationships documented here raise questions about how and in what ways the stiffness of footwear heels influence injury risk during human walking and running. PMID:25814181

  16. Fault Slip Partitioning in the Eastern California Shear Zone-Walker Lane Belt: Pliocene to Late Pleistocene Contraction Across the Mina Deflection

    NASA Astrophysics Data System (ADS)

    Lee, J.; Stockli, D.; Gosse, J.

    2007-12-01

    Two different mechanisms have been proposed for fault slip transfer between the subparallel NW-striking dextral- slip faults that dominant the Eastern California Shear Zone (ECSZ)-Walker Lane Belt (WLB). In the northern WLB, domains of sinistral-slip along NE-striking faults and clockwise block rotation within a zone of distributed deformation accommodated NW-dextral shear. A somewhat modified version of this mechanism was also proposed for the Mina deflection, southern WLB, whereby NE-striking sinistral faults formed as conjugate faults to the primary zone of NW-dextral shear; clockwise rotation of the blocks bounding the sinistral faults accommodated dextral slip. In contrast, in the northern ECSZ and Mina deflection, domains of NE-striking pure dip-slip normal faults, bounded by NW-striking dextral-slip faults, exhibited no rotation; the proposed mechanism of slip transfer was one of right-stepping, high angle normal faults in which the magnitude of extension was proportional to the amount of strike-slip motion transferred. New geologic mapping, tectonic geomorphologic, and geochronologic data from the Queen Valley area, southern Mina deflection constrain Pliocene to late Quaternary fault geometries, slip orientations, slip magnitudes, and slip rates that bear on the mechanism of fault slip transfer from the relatively narrow northern ECSZ to the broad deformation zone that defines the Mina deflection. Four different fault types and orientations cut across the Queen Valley area: (1) The NE-striking normal-slip Queen Valley fault; (2) NE-striking sinistral faults; (3) the NW-striking dextral Coyote Springs fault, which merges into (4) a set of EW-striking thrust faults. (U-Th)/He apatite and cosmogenic radionuclide data, combined with magnitude of fault offset measurements, indicate a Pliocene to late Pleistocene horizontal extension rate of 0.2-0.3 mm/yr across the Queen Valley fault. Our results, combined with published slip rates for the dextral White Mountain

  17. A wrist-walker exhibiting no "Uner Tan Syndrome": a theory for possible mechanisms of human devolution toward the atavistic walking patterns.

    PubMed

    Tan, Uner

    2007-01-01

    After discovering two families with handicapped children exhibiting the "Uner Tan syndrome," the author discovered a man exhibiting only wrist-walking with no primitive mental abilities including language. According to his mother, he had an infectious disease with high fever as a three months old baby; as a result, the left leg had been paralyzed after a penicilline injection. This paralysis most probably resulted from a viral disease, possibly poliomyelitis. He is now (2006) 36 years old; the left leg is flaccid and atrophic, with no tendon reflexes; however, sensation is normal. The boy never stood up on his feet while maturing. The father forced him to walk upright using physical devices and making due exercises, but the child always rejected standing upright and walking in erect posture; he always preferred wrist-walking; he expresses that wrist-walking is much more comfortable for him than upright-walking. He is very strong now, making daily body building exercises, and walking quite fast using a "three legs," although he cannot stand upright. Mental status, including the language and conscious experience, is quite normal. There was no intra-familiar marriage as in the two families mentioned earlier, and there is no wrist-walking in his family and relatives. There were no cerebellar signs and symptoms upon neurological examination. The brain-MRI was normal; there was no atrophy in cerebellum and vermis. It was concluded that there may be sporadic wrist-walkers exhibiting no "Uner Tan Syndrome." The results suggest that the cerebellum has nothing to do with human wrist-walking, which may rather be an atavistic trait appearing from time to time in normal individuals, indicating a live model for human reverse evolution. It was concluded that pure quadrupeds may sporadically appear due to random fluctuations in genotypes and/or environmental factors (hormonal or nutritional); the human development following the human evolution may be stopped in the stage of

  18. Relationships between body weight of overwintering larvae and supercooling capacity; diapause intensity and post-diapause reproductive potential in Chilo suppressalis Walker.

    PubMed

    Xu, Shu; Wang, Ming-Liang; Ding, Nan; Ma, Wei-Hua; Li, Yan-Ning; Lei, Chao-Liang; Wang, Xiao-Ping

    2011-05-01

    The rice stem borer, Chilo suppressalis Walker, overwinters in China as a larva in facultative diapause. The instars and body weights of overwintering larvae vary widely. In this paper, the relationships between body weight and supercooling capacity, diapause intensity and post-diapause reproductive potential of overwintering larvae collected in late-stage rice field were examined. There was a significant positive correlation between body weight, instar, and head capsule width, thus the overwintering larvae were divided into five groups based on body weight (I, up to 35.0mg; II, 35.1-57.0mg; III, 57.1-79.0mg; IV, 79.1-101.0mg; and V, over 101.1mg) for further analysis. The body water content of the lighter group (I) was significantly higher than that of the heavier groups (IV-V). However, the mean supercooling point decreased with an increase of the mean larval body weight in five groups; mean supercooling point of group I was significantly lower than that of group V, except in January 2009. After transfer of overwintering larvae to 15, 20 and 25°C on different dates, smaller individuals pupated slightly faster than larger ones at the same temperature, suggesting that diapause was less intense in smaller overwintering larvae. On 19 March 2009 there was a strong positive correlation between larval body weight and the weight of 3 day-old pupae, and the number of eggs carried by 2 day-old adult females at 15, 20 and 25°C. The average number of eggs carried by 2 day-old adult females differed significantly among different groups. The average number of eggs carried by 2 day-old adult females in group V was significantly greater than those of other groups, and that of group I was significantly lower than those of other groups, suggesting that post-diapause reproductive potential was determined, to a certain extent, by body weight of the overwintering larvae.

  19. Antitumor and anti-cachectic effects of shark liver oil and fish oil: comparison between independent or associative chronic supplementation in Walker 256 tumor-bearing rats

    PubMed Central

    2013-01-01

    Background Shark liver oil (SLOil) and fish oil (FOil), which are respectively rich in alkylglycerols (AKGs) and n-3 polyunsaturated fatty acids (PUFAs), are able to reduce the growth of some tumors and the burden of cachexia. It is known that FOil is able to reduce proliferation rate and increase apoptotic cells and lipid peroxidation of tumor cells efficiently. However, there are few reports revealing the influence of SLOil on these parameters. In the current study, effects of FOil chronic supplementation on tumor growth and cachexia were taken as reference to compare the results obtained with SLOil supplementation. Also, we evaluated if the association of SLOil and FOil was able to promote additive effects. Methods Weanling male Wistar rats were divided into 4 groups: fed regular chow (C), supplemented (1 g/kg body weight) with SLOil (CSLO), FOil (CFO) and both (CSLO + FO). After 8 weeks half of each group was inoculated with Walker 256 cells originating new groups (W, WSLO, WFO and WSLO + FO). Biochemical parameters of cachexia, tumor weight, hydroperoxide content, proliferation rate and percentage of apoptotic tumor cells were analysed. Fatty acids and AKG composition of tumor and oils were obtained by high performance liquid chromatography and gas chromatography – mass spectrometry, respectively. Statistical analysis was performed by unpaired t-test and one-way ANOVA followed by a post hoc Tukey test. Results Fourteen days after inoculation, SLOil was able to restore cachexia parameters to control levels, similarly to FOil. WSLO rats presented significantly lower tumor weight (40%), greater tumor cell apoptosis (~3-fold), decreased tumor cell proliferation (35%), and higher tumor content of lipid hydroperoxides (40%) than observed in W rats, but FOil showed more potent effects. Supplementation with SLOil + FOil did not promote additive effects. Additionally, chromatographic results suggested a potential incorporation competition between the n

  20. Translation vs. Rotation: The Battle for Accommodation of Dextral Shear at the Northern Terminus of the Central Walker Lane, Western Nevada

    NASA Astrophysics Data System (ADS)

    Carlson, C. W.; Faulds, J. E.

    2014-12-01

    Positioned between the Sierra Nevada microplate and Basin and Range in western North America, the Walker Lane (WL) accommodates ~20% of the dextral motion between the North American and Pacific plates on predominately NW-striking dextral and ENE to E-W-striking sinistral fault systems. The Terrill Mountains (TM) lie at the northern terminus of a domain of dextral faults accommodating translation of crustal-blocks in the central WL and at the southeast edge of sinistral faults accommodating oroclinal flexure and CW rotation of blocks in the northern WL. As the mechanisms of strain transfer between these disparate fault systems are poorly understood, the thick Oligocene to Pliocene volcanic strata of the TM area make it an ideal site for studying the transfer of strain between regions undergoing differing styles of deformation and yet both accommodating dextral shear. Detailed geologic mapping and paleomagnetic study of ash-flow tuffs in the TM region has been conducted to elucidate Neogene strain accommodation for this transitional region of the WL. Strain at the northernmost TM appears to be transferred from a system of NW-striking dextral faults to a system of ~E-W striking sinistral faults with associated CW flexure. A distinct ~23 Ma paleosol is locally preserved below the tuff of Toiyabe and provides an important marker bed. This paleosol is offset with ~6 km of dextral separation across the fault bounding the NE flank of the TM. This fault is inferred as the northernmost strand of the NW-striking, dextral Benton Spring fault system, with offset consistent with minimums constrained to the south (6.4-9.6 km, Gabbs Valley Range). Paleomagnetic results suggest counter-intuitive CCW vertical-axis rotation of crustal blocks south of the domain boundary in the system of NW-striking dextral faults, similar to some other domains of NW-striking dextral faults in the northern WL. This may result from coeval dextral shear and WNW-directed extension within the left