Science.gov

Sample records for versigonalia ruficauda walker

  1. Foldable Walker

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Paraplegics, who number about 100,000 in the United States, depend on crutches for their mobility on level ground. But crutches are ineffective on stairways; for climbing or descending, the paraplegic needs a stable pair of rails to push against. Aluminum metal walkers are designed for use on level surfaces, hence they have little utility on stairs; and, although lightweight, they are too heavy to be carried by the paraplegic while walking on crutches. There exists a need for a walker specifically designed for stair use and made of material much lighter than aluminum.

  2. Compliant Walker

    NASA Technical Reports Server (NTRS)

    Kerley, James J.; Eklund, Wayne; Crane, Alan

    1992-01-01

    Walker supports person with limited use of legs and back. Enables person to stand upright, move with minimum load, and rest at will taking weight off legs. Consists of wheeled frame with body harness connected compliantly to side structures. Harness supports wearer upright when wearer relaxes and takes weight off lower extremities. Assumes partial to full body weight at user's discretion.

  3. 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.

  4. Dissimilar bouncy walkers

    NASA Astrophysics Data System (ADS)

    Lomholt, Michael A.; Lizana, Ludvig; Ambjörnsson, Tobias

    2011-01-01

    We consider the dynamics of a one-dimensional system consisting of dissimilar hardcore interacting (bouncy) random walkers. The walkers' (diffusing particles') friction constants ? _n, where n labels different bouncy walkers, are drawn from a distribution \\varrho (? _n). We provide an approximate analytic solution to this recent single-file problem by combining harmonization and effective medium techniques. Two classes of systems are identified: when \\varrho (? _n) is heavy-tailed, \\varrho (? _n)˜eq ? _n^{-1-? } (0

  5. Dissimilar bouncy walkers.

    PubMed

    Lomholt, Michael A; Lizana, Ludvig; Ambjörnsson, Tobias

    2011-01-28

    We consider the dynamics of a one-dimensional system consisting of dissimilar hardcore interacting (bouncy) random walkers. The walkers' (diffusing particles') friction constants ?(n), where n labels different bouncy walkers, are drawn from a distribution ?(?(n)). We provide an approximate analytic solution to this recent single-file problem by combining harmonization and effective medium techniques. Two classes of systems are identified: when ?(?(n)) is heavy-tailed, ?(?(n))??(n) (-1-?)?(0

  6. 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.

  7. 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 injured in a mid-air collision between the planes. Joe graduated from Washington and Jefferson College in 1942, with a Bachelors degree in Physics. He enrolled in the civilian pilot training program in 1941 and, after graduation from college, entered the Army Air Forces. During World War II he flew P-38 fighters and F-5A photo reconnaissance for the Air Force, earning the Distinguished Flying Cross and the Air Medal with Seven Oak Clusters. Walker was a charter member of the Society of Experimental Test Pilots and one of the first to be designated a Fellow. He was honored with the Robert J. Collier Trophy, the Harmon International Trophy for Aviators, the Iven C. Kincheloe Award and the Octave Chanute Award, all in 1961. He received an honorary Doctor of Aeronautical Sciences degree from his alma mater in June of 1961 and was named Pilot of the Year in 1963 by the National Pilots Association. Joseph Albert Walker was born February 20, 1921, in Washington, Pennsylvania; he died on June 8, 1966 at Edwards, California.

  8. Light-Fueled Microscopic Walkers.

    PubMed

    Zeng, Hao; Wasylczyk, Piotr; Parmeggiani, Camilla; Martella, Daniele; Burresi, Matteo; Wiersma, Diederik Sybolt

    2015-07-01

    The first microscopic artificial walker equipped with liquid-crystalline elastomer muscle is reported. The walker is fabricated by direct laser writing, is smaller than any known living terrestrial creatures, and is capable of several autonomous locomotions on different surfaces. PMID:26033690

  9. 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.

  10. 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.

  11. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged...

  12. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged...

  13. Thad G. Walker Research Highlights

    E-print Network

    Yavuz, Deniz

    . Rev. Lett. (accepted), ArXiv:1310.7561 (2013) eprint 114. "Preparation of a single atom in an opticalThad G. Walker Research Highlights LASER TRAPPING AND COOLING OF ATOMS Laser cooling methods have made a dramatic impact on atomic physics, resulting in three No- bel Prizes. Laser cooled atoms

  14. October 6, 2006 Mark Walker

    E-print Network

    October 6, 2006 Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851 the Northwest Power & Conservation Council to reconsider funding the Juvenile Fish Screen Evaluation in Columbia and Passage Program. Our involvement with these screening activities has evolved submitting proposals to BPA

  15. 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 slowdown on newly visited sites, owing to catalysis, can improve the mean first passage time of spiders and show that in one dimension, when both ends of the track are an absorbing boundary, the performance gain is lower than in two dimensions, when the absorbing boundary is a circle; this persists even when the absorbing boundary is a single site. Next, we study how multiple molecular spiders influence one another during the search. We show that when one spider reaches the trace of another spider it is more likely not to follow the trace and instead explore unvisited sites. This interaction between the spiders gives them an advantage over independent random walkers in a search for multiple targets. We also study how efficiently the spiders with various gaits are able to find specific targets. Spiders with gaits that allow more freedom of leg movement find their targets faster than spiders with more restrictive gaits. For every gait, there is an optimal detachment rate that minimizes the time to find all target sites.

  16. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a) Identification. A mechanical...

  17. Walker Branch Watershed Ecosystems Data

    DOE Data Explorer

    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

  18. 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....

  19. 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....

  20. 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....

  1. 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....

  2. 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....

  3. A Reflection Principle for Three Vicious Walkers

    E-print Network

    Chen, William Y C; Zhang, Terence Y J

    2008-01-01

    We establish a reflection principle for three lattice walkers and use this principle to reduce the enumeration of the configurations of three vicious walkers to that of configurations of two vicious walkers. In the combinatorial treatment of two vicious walkers, we make connections to two-chain watermelons and to the classical ballot problem. Precisely, the reflection principle leads to a bijection between three walks $(L_1, L_2, L_3)$ such that $L_2$ intersects both $L_1$ and $L_3$ and three walks $(L_1, L_2, L_3)$ such that $L_1$ intersects $L_3$. Hence we find a combinatorial interpretation of the formula for the generating function for the number of configurations of three vicious walkers, originally derived by Bousquet-M\\'elou by using the kernel method, and independently by Gessel by using tableaux and symmetric functions.

  4. Averaging Robertson-Walker cosmologies

    SciTech Connect

    Brown, Iain A.; Robbers, Georg; Behrend, Juliane E-mail: G.Robbers@thphys.uni-heidelberg.de

    2009-04-15

    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 {Lambda}CDM concordance model, the backreaction is of the order of {Omega}{sub eff}{sup 0} Almost-Equal-To 4 Multiplication-Sign 10{sup -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{sup -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 w{sub eff} < -1/3 can be found for strongly phantom models.

  5. Undergraduate Programs Walker College of Business

    E-print Network

    Thaxton, Christopher S.

    Appalachian Accounting graduate and Tax Associate for Grant Thornton, LLP #12;Points of Pride AACSB Accreditation The Walker College is accredited by AACSB International ­ the premier global accrediting body

  6. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

    Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific-North American transform plate motion. The Walker Lane is composed of discontinuous sets of right-slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right-lateral shear is locally accommodated by rotation of crustal blocks bounded by steep-dipping east striking left-slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right-lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike-slip faults in the central Walker Lane is abrupt and reflects transfer of strike-slip to dip-slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long-lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic-brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker Lane and that oblique components of displacement are of opposite sense along the Walker Lane (extension) and San Andreas (contraction), respectively. Despite the gross differences in fault pattern, the Walker Lane and San Andreas also share similarities in deformation style, including clockwise rotations of crustal blocks leading to development of structural basins and the partitioning of oblique components of slip onto subparallel strike-slip and dip-slip faults.

  7. 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.

  8. Technical considerations in the selection and performance of walkers.

    PubMed

    Nabizadeh, S A; Hardee, T B; Towler, M A; Chen, V T; Edlich, R F

    1993-01-01

    The walker is a mobility aid that provides a portable base of support. People of all ages use different kinds of walkers for a variety of reasons. With the correct walker, many people stroll along at the same pace as their companion. Today, walkers are available in a variety of styles and colors and have numerous accessories. It is the purpose of this article to describe the various types and models of walkers and accessories that are available. Our goal is not to recommend or rate the walkers but to help you find the right walker. The ultimate selection of a walker will depend on a cooperative effort between the physiatrist, physical therapist, and medical equipment supplier. Before you purchase a walker you should test it out to decide if it is the right one for you. The physical therapist who supplies your walker should adjust for your height and should check the physical fit of the equipment. Moreover, the physical therapist should demonstrate the proper gait for walking. During the past few years radical changes have occurred in the design and style of walkers. We expect this trend to continue with more attractive, easier-to-use products to be introduced regularly. If you think that your walker is outdated and is not adapting to your lifestyle, talk with your physiatrist regarding alternatives. Today, walkers are as different as their users. Find the best one for you by taking a test walk in your home and community. PMID:8501107

  9. Dynamical Backreaction in Robertson-Walker Spacetime

    E-print Network

    Benjamin Eltzner; Hanno Gottschalk

    2011-04-07

    The treatment of a quantized field in a curved spacetime requires the study of backreaction of the field on the spacetime via the semiclassical Einstein equation. We consider a free scalar field in spatially flat Robertson-Walker space time. We require the state of the field to allow for a renormalized semiclassical stress tensor. We calculate the sigularities of the stress tensor restricted to equal times in agreement with the usual renormalization prescription for Hadamard states to perform an explicit renormalization. The dynamical system for the Robertson Walker scale parameter $a(t)$ coupled to the scalar field is finally derived for the case of conformal and also general coupling.

  10. Dual position locking joint design for a medical walker

    E-print Network

    Beecher, Eric M

    2010-01-01

    In this thesis we analyzed a joint created for a medical walker currently in the prototyping stage of development. The walker is designed to help a user stand up from a seated position. The joint holds two legs of the ...

  11. 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 indicates that most of this silty material is the result of slope wash processed during the Holocene Age. Residual soils of the watershed were related to the underlying geologic formations by their morphology and types of chert. Colluvial soils were identified and mapped whenever the colluvium thickness exceeded 20 in. (50 cm). Except for the ancient colluvial soils (colluvium without a present-day source area), colluvial soils were not separated according to their geologic age, but stacked colluvial deposits are located in low footslope landforms. Colluvial soils in the watershed were identified and mapped according to their morphologic properties that would influence the perching and subsurface movement of water. Alluvial soils were restricted to present floodplains, low fan terraces, and low fan deltas. Nearly all alluvial soils contained very young surficial sediments derived from slopewash resulting from land clearing and subsequent agricultural activities.

  12. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the swivel...walker weight g = acceleration of gravity = 32.2 ft/sec2 (ii) [Reserved...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the...

  13. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the swivel...walker weight g = acceleration of gravity = 32.2 ft/sec2 (ii) [Reserved...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the...

  14. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the swivel...walker weight g = acceleration of gravity = 32.2 ft/sec2 (ii) [Reserved...dummy and walker g = acceleration of gravity = 32.2 ft/sec2 Position the...

  15. Mark Walker Director of Public Affairs

    E-print Network

    Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851 SW 6th Avenue for electrical power generation. That is a waste of a clean burning fuel that can easily be distributed can easily be distributed. I also believe nuclear power needs to be given much higher priority

  16. Sara Walker | Physical Sciences in Oncology

    Cancer.gov

    Sara Walker works in the School of Life Science and the Beyond Center at Arizona State University. She is also a NASA Astrobiology fellow. She spoke about the deep evolutionary history of life on earth and it’s routes to cancer.

  17. Perioperative considerations in Walker–Warburg syndrome

    PubMed Central

    Valk, Madelous JA; Loer, Stephan A; Schober, Patrick; Dettwiler, Saskia

    2015-01-01

    Key Clinical Message Walker–Warburg syndrome is a rare congenital disorder. Several features, including muscular dystrophy, hydrocephalus, and oropharyngeal abnormalities, have important implications in the perioperative setting. We present a case of general anesthesia in an infant and discuss perioperative considerations to guide clinicians faced with the management of patients with this syndrome. PMID:26401279

  18. 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…

  19. Mark Walker Director of Public Affairs

    E-print Network

    , Suite 1100 Portland, OR 97204 Mr. Walker: Please accept these comments from Emerald People's Utility future? Yes, this issue needs to be resolved in the near future. We believe that Emerald resources could lead to energy shortages and higher prices. Emerald is specifically interested in going

  20. ENERGY, WEATHER AND Walker Institute Research

    E-print Network

    Hodges, Kevin

    ENERGY, WEATHER AND CLIMATE Walker Institute Research Climate scientists and engineers are working together to understand the impacts of weather and climate on energy systems. WEATHER, CLIMATE AND ENERGY/POWER SYSTEMS Weather and climate can affect many aspects of modern power systems. For example, intense storms

  1. 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.

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

    E-print Network

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

    2000-11-07

    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.

  3. 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.

  4. Prevention strategies for infant walker-related injuries.

    PubMed

    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

  5. VICIOUS WALKERS, FRIENDLY WALKERS AND YOUNG TABLEAUX II: WITH A WALL

    E-print Network

    Krattenthaler, Christian

    and watermelon configu­ rations of vicious walkers in the presence of an impenetrable wall by showing and watermelons both in the absence of a wall and in the presence of a wall. 1. Introduction In an earlier paper was obtained, and the result for the corresponding number of watermelon configurations was conjectured. Later

  6. 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 cosmic rays within these samples. He and Dr. Crozaz were married in 1973. In the past two decades, he was a world leader of microanalytical studies of tiny grains preserved for eons in meteorites, culminating in their identification as stardust. More recent achievements include the design of micrometeorite capture cells that were flown aboard NASA's Long Duration Exposure Facility; verification of the extraterrestrial origin of dust particles collected in the upper atmosphere; and the successful search for interstellar grains in meteorites. "Bob was such a dominant force for excellence in our department and the University over so many years, it is hard to grasp that he is gone," said John W. Clark, PhD, chair of physics, the Wayman Crow Professor and a faculty fellow of the McDonnell Center. "His passion for life and science was an inspiration to us all, and his legacy will endure in the work of his many colleagues and the extended family of his former students." Walker led the McDonnell Center, which includes one of the world's largest research groups dedicated to the search for and investigation of extraterrestrial materials, until 1999. "Washington University would be a lesser institution without the contributions of Bob Walker," said William H. Danforth, chancellor emeritus and vice chairman of the Board of Trustees. "He gave us inspiration, enthusiasm, great science and visionary leadership. He built the strength of the McDonnell Center for the Space Sciences. He convinced others of the potential for the modern Department of Earth and Planetary Sciences. He had always the respect and affection of us all." The last two decades of Walker's career were driven by his remarkable vision and his excitement at the prospect of profound discovery. His recognition of the potential importance of the ion microprobe for making isotopic measurements on microscopic samples, and his acquisition in 1982 of a state-of-the-art instrument for the University, led directly to a series of spectacular results. Chief among these was the ident

  7. 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

    ...Testing for Certain Children's Products; Infant Walkers: Requirements...Testing for Certain Children's Products; Infant Walkers: Requirements...Acceptance of Children's Product Certifications...Safety Standard for Infant Walkers Prior...

  8. 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. PMID:21665475

  9. Quantum Cohomology via Vicious and Osculating Walkers

    NASA Astrophysics Data System (ADS)

    Korff, Christian

    2014-07-01

    We relate the counting of rational curves intersecting Schubert varieties of the Grassmannian to the counting of certain non-intersecting lattice paths on the cylinder, so-called vicious and osculating walkers. These lattice paths form exactly solvable statistical mechanics models and are obtained from solutions to the Yang-Baxter equation. The eigenvectors of the transfer matrices of these models yield the idempotents of the Verlinde algebra of the gauged -WZNW model. The latter is known to be closely related to the small quantum cohomology ring of the Grassmannian. We establish further that the partition functions of the vicious and osculating walker model are given in terms of Postnikov's toric Schur functions and can be interpreted as generating functions for Gromov-Witten invariants. We reveal an underlying quantum group structure in terms of Yang-Baxter algebras and use it to give a generating formula for toric Schur functions in terms of divided difference operators which appear in known representations of the nil-Hecke algebra.

  10. Hamlet: Force/Position Controlled Hexapod Walker -Design and Systems

    E-print Network

    Portland State University

    1 Hamlet: Force/Position Controlled Hexapod Walker - Design and Systems Michael R. Fielding , Christopher J. Damaren and Reg Dunlop Abstract--Hamlet is a hexapod walker constructed at the University Hamlet is that by using the forces at the feet to modify their positions during stance, on a leg by leg

  11. THE MORPHIC ABEL-JACOBI MAP MARK E. WALKER

    E-print Network

    THE MORPHIC ABEL-JACOBI MAP MARK E. WALKER. WALKER X. It is a continuous homomorphism of abelian groups, r : Zr(X)hom,0 ! Jr(X), from the space Zr(X)hom,0 of r-cycles on X that are homologically equivalent to zero (i

  12. A business plan for iXa walker

    E-print Network

    Morton, Stephen A

    2010-01-01

    A market study was performed to determine the feasibility of the iXa Walker. The walker industry is about to enter a large growth due to the entry of millions of baby boomers into the durable medical equipment market. Using ...

  13. 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...) Table 1 Summary of Step(s) Tests Section No. Facing direction of walker Weight of CAMI dummy, lb... the front edge of the platform and the walker is distance d from the center of the most forward...

  14. COPESTYLUM CIRCUMDATUM (WALKER) (DIPTERA: SYRPHIDAE). A REDESCRIPTION, WITH LECTOTYPE DESIGNATIONS AND NEW SYNONYM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Copestylum circumdatum (Walker) (Diptera: Syrphidae) is redescribed. Lectotypes are designated for two names and one new synonym is proposed (Volucella mus Williston 1888 = circumdatum Walker 1857)....

  15. 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

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

    PubMed

    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

  17. 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.

  18. 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

  19. A review of the functionalities of smart walkers.

    PubMed

    Martins, Maria; Santos, Cristina; Frizera, Anselmo; Ceres, Ramón

    2015-10-01

    There is a need to conceptualize and improve the investigation and developments in assistive devices, focusing on the design and effectiveness of walkers in the user's rehabilitation process and functional compensation. This review surveys the importance of smart walkers in maintaining mobility and discusses their potential in rehabilitation and their demands as assistive devices. It also presents related research in addressing and quantifying the smart walker's efficiency and influence on gait. Besides, it discusses smart walkers focusing on studies related to the concept of autonomous and shared-control and manual guidance, the use of smart walkers as personal helpers to sit-to-stand and diagnostic tools for patients' rehabilitation through the evaluation of their gait. PMID:26307456

  20. 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,…

  1. Instability of Walker propagating domain wall in magnetic nanowires.

    PubMed

    Hu, B; Wang, X R

    2013-07-12

    The stability of the well-known Walker propagating domain wall (DW) solution of the Landau-Lifshitz-Gilbert equation is analytically investigated. Surprisingly, a propagating DW is always dressed with spin waves so that the Walker rigid-body propagating DW mode does not occur in reality. In the low field region only stern spin waves are emitted while both stern and bow waves are generated under high fields. In a high enough field, but below the Walker breakdown field, the Walker solution could be convective or absolute unstable if the transverse magnetic anisotropy is larger than a critical value, corresponding to a significant modification of the DW profile and DW propagating speed. PMID:23889437

  2. On the Hadamard condition on Robertson-Walker spacetime

    E-print Network

    Jan Tichavsky

    2006-09-04

    Using construction of adiabatic vacuum states of a free scalar field on Robertson-Walker spacetime, using results of Luders and Roberts we prove that validity of the Hadamard condition implies smoothness of the scale factor.

  3. 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, first on July 20, 1951). These flights investigated pitch-up and evaluated outboard wing fences. Walt also made research flights in the Northrop X-4 (14 flights, first on March 26, 1952) and the Bell X-5 (8 flights, first on June 20, 1952). In July 1952, Walt left NACA's High-Speed Flight Research Station to join Northrop Corporation as a pilot. Returning from a test mission in a Northrop YF-89D Scorpion he was fatally injured on October 20, 1953, near Edwards Air Force Base.

  4. An Archaeological Survey for the Walker County Special Utility District Water System Improvement Project in Central Walker County Texas 

    E-print Network

    Moore, William; Baxter, William

    2015-07-28

    without further consultation with the Texas Historical Commission (THC). Copies of the report are on file at the Texas Historical Commission (THC), Archeology Division, the Texas Archeological Research Laboratory (TARL), the Walker County Special Utility...

  5. 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.

  6. Conformally Friedmann-Lemaître-Robertson-Walker cosmologies

    NASA Astrophysics Data System (ADS)

    Visser, Matt

    2015-07-01

    In a Universe where, according to the standard cosmological models, some 97% of the total mass-energy is still ‘missing in action’, it behooves us to spend at least a little effort critically assessing and exploring radical alternatives. Among possible (dare we say plausible), nonstandard but superficially viable models, those spacetimes conformal to the standard Friedmann-Lemaître-Robertson-Walker (FLRW) class of cosmological models play a very special role—these models have the unique and important property of permitting large non-perturbative geometric deviations from FLRW cosmology without unacceptably distorting the cosmic microwave background. Performing a ‘cosmographic’ analysis (that is, temporarily setting aside the Einstein equations, since the question of whether or not the Einstein equations are valid on galactic and cosmological scales is essentially the same question as whether or not dark matter/dark energy actually exist), and using both supernova data and information about galactic structure, one can nevertheless place some quite significant observational constraints on any possible conformal mode—however, there is still an extremely rich range of phenomenological possibilities for both cosmologists and astrophysicists to explore.

  7. 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. On Oct. 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system of increased capacity, and a thinner high-speed wing. The X-1E was used to obtain in-flight data at twice the speed of sound, with particular emphasis placed on investigating the improvements achieved with the high-speed wing. These wings, made by Stanley Aircraft, were only 3 3/8-inches thick at the root and had 343 gauges installed in them to measure structural loads and aerodynamic heating. The X-1E used its rocket engine to power it up to a speed of 1,471 miles per hour (Mach 2.24) and to an altitude of 73,000 feet. Like the X-1 it was air-launched. The X-1 aircraft were almost 31 feet long and had a wingspan of 28 feet. The X-1 was built of conventional aluminum stressed-skin construction to extremely high structural standards. The X-1E was also 31 feet long but had a wingspan of only 22 feet, 10 inches. It was powered by a Reaction Motors, Inc., XLR-8-RM-5, four-chamber rocket engine. As did all X-1 rocket engines, the LR-8-RM-5 engine did not have throttle capability, but instead, depended on ignition of any one chamber or group of chambers to vary speed. The X-1A, X-1B, and the X-1D were growth versions of the X-1. They were almost five feet longer, almost 2,500 pounds heavier and had conventional canopies. The X-1A and X-1B were modified to have ejection seats. Their mission was to continue the X-1 studies at higher speeds and altitudes. The X-1A began this research after the X-1D was destroyed in an explosion on a captive flight before it made any research flights. On Dec. 12, 1953, Major Charles Yeager flew the X-1A up to a speed of 1,612 miles per hour (almost two-and-a-half times the speed of sound). Then on Aug. 26, 1954, Major Arthur Murray took the X-1A up to an altitude of 90,4

  8. Trends in the local Hadley and local Walker circulations

    NASA Astrophysics Data System (ADS)

    Schwendike, Juliane; Berry, Gareth J.; Reeder, Michael J.; Jakob, Christian; Govekar, Pallavi; Wardle, Richard

    2015-08-01

    The linear trend in the local Hadley and Walker circulations from 1979 to 2009 is calculated. These local circulations are defined through a decomposition of the vertical mass flux into its zonal and meridional components. Defining the local circulation this way ensures that the two orthogonal circulations (the local Hadley and Walker circulations) sum to the original circulation even after averaging the circulations regionally. Large regional differences in changes in the local Hadley and Walker circulations over a 31 year period are found. For example, the local Hadley circulation has shifted southward over Africa, the Maritime Continent, and the western and central Pacific by about 1°. Over the Americas and the Atlantic the local Hadley circulation has strengthened by about 1-5%. The zonal component of the vertical mass flux has increased by about 10-20% in the tropics over all continents and decreased over the adjacent oceans by about 10-20%. Although the local Walker circulations in the Indian Ocean and the Atlantic have weakened, the circulation in the Pacific has changed little (about 1-2%). The local Walker circulations in all ocean basins have shifted westward by about 1-2°on average.

  9. 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 wind speeds were identical during El Niño, La Niña and normal conditions. In the east Pacific, the shear between 10- and 700-m heights increased (decreased) during La Niña (El Niño).

  10. Optically Resolving the Dynamic Walking of a Plasmonic Walker Couple.

    PubMed

    Urban, Maximilian J; Zhou, Chao; Duan, Xiaoyang; Liu, Na

    2015-12-01

    Deterministic placement and dynamic manipulation of individual plasmonic nanoparticles with nanoscale precision feature an important step toward active nanoplasmonic devices with prescribed levels of performance and functionalities at optical frequencies. In this Letter, we demonstrate a plasmonic walker couple system, in which two gold nanorod walkers can independently or simultaneously perform stepwise walking powered by DNA hybridization along the same DNA origami track. We utilize optical spectroscopy to resolve such dynamic walking with nanoscale steps well below the optical diffraction limit. We also show that the number of walkers and the optical response of the system can be correlated. Our studies exemplify the power of plasmonics, when integrated with DNA nanotechnology for realization of advanced artificial nanomachinery with tailored optical functionalities. PMID:26571209

  11. Evidence for weakening of the Walker circulation from cloud observations

    NASA Astrophysics Data System (ADS)

    Bellomo, Katinka; Clement, Amy C.

    2015-09-01

    Climate models simulate a weakening of the Walker circulation in response to increased greenhouse gases, but it has not been possible to detect this weakening with observations because there are not direct measurements of atmospheric circulation strength. Indirect measurements, such as equatorial gradients in sea level pressure (SLP), exhibit trends of inconsistent sign. In this study we estimate the change in midtropospheric velocity (?500) from observed change in cloud cover, which we argue is more closely tied to the overturning circulation than indirect measurements of SLP at the surface. Our estimates suggest a weakening and eastward shift of the Walker circulation over the last century. Because changes in cloud cover in Atmospheric Model Intercomparison Project simulations forced with increased sea surface temperature are remarkably similar in pattern, sign, and magnitude, we assert that the observed changes in cloud cover and the associated weakening of Walker circulation are at least in part externally forced.

  12. Rev. of American Studies Abroad, ed. by Robert Walker

    E-print Network

    Levine, Stuart

    1976-01-01

    stream_size 4837 stream_content_type text/plain stream_name Levine_1976_Walker_page86.pdf.txt stream_source_info Levine_1976_Walker_page86.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 reform... and region PROGRESSIVISM AND ECONOMIC GROWTH: The Wisconsin Income Tax, 1911- 1929. By Elliot W. Brownlee, Jr. Port Washington, N.Y., and London. National University Publications. Kennikat Press. 1974. $10.00. Historians have tended to assume without...

  13. Smart random walkers: the cost of knowing the path.

    PubMed

    Perotti, Juan I; Billoni, Orlando V

    2012-07-01

    In this work we study the problem of targeting signals in networks using entropy information measurements to quantify the cost of targeting. We introduce a penalization rule that imposes a restriction on the long paths and therefore focuses the signal to the target. By this scheme we go continuously from fully random walkers to walkers biased to the target. We found that the optimal degree of penalization is mainly determined by the topology of the network. By analyzing several examples, we have found that a small amount of penalization reduces considerably the typical walk length, and from this we conclude that a network can be efficiently navigated with restricted information. PMID:23005381

  14. 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.

  15. GMRES ON (NEARLY) SINGULAR SYSTEMS PETER N. BROWN AND HOMER F. WALKER

    E-print Network

    Walker, Homer F.

    GMRES ON (NEARLY) SINGULAR SYSTEMS PETER N. BROWN AND HOMER F. WALKER SIAM J. MATRIX ANAL. APPL. c Computation, Rice University. 37 #12;38 PETER N. BROWN AND HOMER F. WALKER problem. We shall not be more

  16. The Role of Walkers’ Needs and Expectations in Supporting Maintenance of Attendance at Walking Groups: A Longitudinal Multi-Perspective Study of Walkers and Walk Group Leaders

    PubMed Central

    Kassavou, Aikaterini; Turner, Andrew; French, David P.

    2015-01-01

    Background There is good evidence that when people’s needs and expectations regarding behaviour change are met, they are satisfied with that change, and maintain those changes. Despite this, there is a dearth of research on needs and expectations of walkers when initially attending walking groups and whether and how these needs and expectations have been satisfied after a period of attendance. Equally, there is an absence of research on how people who lead these groups understand walkers’ needs and walk leaders’ actions to address them. The present study was aimed at addressing both of these gaps in the research. Methods Two preliminary thematic analyses were conducted on face-to-face interviews with (a) eight walkers when they joined walking groups, five of whom were interviewed three months later, and (b) eight walk leaders. A multi-perspective analysis building upon these preliminary analyses identified similarities and differences within the themes that emerged from the interviews with walkers and walk leaders. Results Walkers indicated that their main needs and expectations when joining walking groups were achieving long-term social and health benefits. At the follow up interviews, walkers indicated that satisfaction with meeting similar others within the groups was the main reason for continued attendance. Their main source of dissatisfaction was not feeling integrated in the existing walking groups. Walk leaders often acknowledged the same reasons for walkers joining and maintaining attendance at walking. However, they tended to attribute dissatisfaction and drop out to uncontrollable environmental factors and/or walkers’ personalities. Walk leaders reported a lack of efficacy to effectively address walkers’ needs. Conclusions Interventions to increase retention of walkers should train walk leaders with the skills to help them modify the underlying psychological factors affecting walkers’ maintenance at walking groups. This should result in greater retention of walkers in walking groups, thereby allowing walkers to receive the long-term social and health benefits of participation in these groups. PMID:25774527

  17. Extending Equilibria to Periodic Orbits for Walkers using Continuation Nelson Rosa Jr. and Kevin M. Lynch

    E-print Network

    Bustamante, Fabián E.

    Extending Equilibria to Periodic Orbits for Walkers using Continuation Methods Nelson Rosa Jr for multi-degree-of-freedom, planar biped walkers. Our approach uses equilibria of the dynamics as templates define a gait as a fixed point of the walker's hybrid dynamics which resides in a state

  18. Factors Associated with Women's Antenatal Plans to Use a Baby Walker: A Cross Sectional Study

    ERIC Educational Resources Information Center

    Illingworth, Rachel; Kendrick, Denise; Collier, Jacqueline; Woods, Amanda; Wattse, Kim; Dewey, Michael; Chen, Chih-Mei

    2006-01-01

    Objective: The objective of these analyses was to explore maternal antenatal decisions about baby walker use, factors associated with these decisions and the relationship between antenatal plans to use a walker and postnatal walker use. Design: Cross sectional study. Setting: Mothers-to-be (n = 1174) participating in a cluster randomised…

  19. Persons using crutches, canes or walkers: Disabled Persons

    E-print Network

    Meyers, Steven D.

    Persons using crutches, canes or walkers: Disabled Persons In emergency evacuations a chair with arms, and follow the procedure for non- ambulatory persons discussed below. Non-ambulatory persons: Evacuation may not be necessary or advisable. Many stairwells are designed to provide temporary

  20. Some Issues in Creating `Invertebrate' Robots I.D. Walker

    E-print Network

    Some Issues in Creating `Invertebrate' Robots I.D. Walker Clemson University, Dept. Electrical issues involved in the design, analysis, and implementation of `invertebrate- like' robots. Using as case, in invertebrate structures such as those in `tongues, trunks, and tentacles', highly dextrous ma- nipulation can

  1. Moments of vicious walkers and Möbius graph expansions

    NASA Astrophysics Data System (ADS)

    Katori, Makoto; Komatsuda, Naoaki

    2003-05-01

    A system of Brownian motions in one dimension all started from the origin and conditioned never to collide with each other in a given finite time interval (0,T] is studied. The spatial distribution of such vicious walkers can be described by using the repulsive eigenvalue statistics of random Hermitian matrices and it was shown that the present vicious walker model exhibits a transition from the Gaussian unitary ensemble (GUE) statistics to the Gaussian orthogonal ensemble (GOE) statistics as the time t goes on from 0 to T. In the present paper, we characterize this GUE-to-GOE transition by presenting the graphical expansion formula for the moments of positions of vicious walkers. In the GUE limit t?0, only the ribbon graphs contribute and the problem is reduced to the classification of orientable surfaces by genus. Following the time evolution of the vicious walkers, however, the graphs with twisted ribbons, called Möbius graphs, increase their contribution to our expansion formula, and we have to deal with the topology of nonorientable surfaces. Application of the recent exact result of dynamical correlation functions yields closed expressions for the coefficients in the Möbius expansion using the Stirling numbers of the first kind.

  2. How clonal are human mitochondria? Adam Eyre-Walker*

    E-print Network

    Eyre-Walker, Adam

    How clonal are human mitochondria? Adam Eyre-Walker* , Noel H. Smith and John Maynard Smith Centre many homoplasies, i.e. back or parallel changes at a site (e.g. see Vigilant et al. 1991). Homoplasies then it is necessary to hypothesize that some sites change more often than others, i.e. that there are `hypervariable

  3. 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…

  4. INTRODUCTION The Eastern California shear zoneWalker

    E-print Network

    Frankel, Kurt L.

    Desert and along the eastern side of the Sierra Nevada. In the Mojave section of the shear zone, faultRESEARCH INTRODUCTION The Eastern California shear zone­Walker Lane belt is an evolving fault; Bennett et al., 2003; Faulds et al., 2005; Wesnousky, 2005a, 2005b; Frankel et al., 2007a). The Eastern

  5. 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 the shore and river mouth that could be boulders, tree stumps, logs, or other submerged objects. The echosounder detected what appeared to be mounds in the deepest parts of Walker Lake, miles from the shore and river mouth. However, side-scan sonar and divers did not confirm the presence of mounds. Anomalies occur in two northwest trending groups in northern and southern Walker Lake. It is hypothesized that some anomalies indicate spring discharge along faults based on tufa-like rocks that were observed and the northwest trend parallel to and in proximity of mapped faults. Also, evaporation measured from Walker Lake is about 50 percent more than the previous estimate, indicating more water is flowing into the lake from sources other than the Walker River. Additional studies need to be done to determine what the anomalies are and whether they are related to the hydrology of Walker Lake. Most differences in surface area and storage volume between this study and a study by Rush in 1970 were less than 1 percent. The largest differences occur at lake-surface altitudes less than 3,916 feet. In general, relations between lake-surface altitude, surface area, and storage volume from Rush's study and this study are nearly identical throughout most of the range in lake-surface altitude. The lake-surface altitude in 1882 was estimated to be between 4,080 feet and 4,086 feet with a probable altitude of 4,082 feet. This estimate compares well with two previous estimates of 4,083 feet and 4,086 feet. Researchers believe the historic highstand of Walker Lake occurred in 1868 and estimated the highstand was between 4,089 feet and 4,108 feet. By 1882, Mason Valley was predominantly agricultural. The 7-26 feet decline in lake-surface altitude between 1868 and 1882 could partially be due to irrigation diversions during this time.

  6. 75 FR 35265 - Safety Standard for Infant Walkers: Final Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... resistance, as well as for the occupant leaning over the front. Dynamic and static load testing on seating... discussed in the preamble to the proposed rule (74 FR at 45706), CPSC staff conducted testing on JPMA... Regulations Banning Certain Baby-Walkers; Third Party Testing for Certain Children's Products; Infant...

  7. Do mitochondria recombine in humans? Adam Eyre-Walker

    E-print Network

    Eyre-Walker, Adam

    Do mitochondria recombine in humans? Adam Eyre-Walker Centre for the Study of Evolution and School recently, mitochondria were thought to be clonally inherited through the maternal line in most higher in mitochondria. Whereas the debate over the clonality of mitochondria has simmered in molecular biology

  8. Random Walker Ranking for NCAA Division I-A Football

    E-print Network

    Porter, Mason A.

    Random Walker Ranking for NCAA Division I-A Football Thomas Callaghan, Peter J. Mucha, and Mason A the top two NCAA Division I-A college football teams in a National Championship game at the end of each in accurately ranking or even agreeing on a ranking methodology for college football lies in two factors

  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. Actuating a Simple 3D Passive Dynamic Walker Russ Tedrake

    E-print Network

    Tedrake, Russ

    Actuating a Simple 3D Passive Dynamic Walker Russ Tedrake Computer Science and Artificial Intelligence Lab Massachusetts Institute of Technology Cambridge, MA 02139 Email: russt@ai.mit.edu Teresa W & Cognitive Sciences Massachusetts Institute of Technology Cambridge, MA 02139 Email: seung@mit.edu Abstract

  11. 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…

  12. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR INFANT WALKERS...F977-12, Standard Consumer Safety Specification for Infant...U.S. Consumer Product Safety Commission, Room 820, 4330...301-504-7923, or at the National Archives and Records...

  13. 75 FR 35265 - Safety Standard for Infant Walkers: Final Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ...for 1 minute. Arguably, the force of gravity is more consistent than a test technician...restrained during testing so that the center of gravity will be consistent from lab to lab...CAMI dummy and walker g = acceleration of gravity = 32.2 ft/sec\\2\\ Position the...

  14. Collision avoidance between two walkers: role-dependent strategies.

    PubMed

    Olivier, Anne-Hélène; Marin, Antoine; Crétual, Armel; Berthoz, Alain; Pettré, Julien

    2013-09-01

    This paper studies strategies for collision avoidance between two persons walking along crossing trajectories. It has been previously demonstrated that walkers are able to anticipate the risk of future collision and to react accordingly. The avoidance task has been described as a mutual control of the future distance of closest approach, MPD (i.e., Mininum Predicted Distance). In this paper, we studied the role of each walker in the task of controlling MPD. A specific question was: does the walker giving way (2nd at the crossing) and the one passing first set similar and coordinated strategies? To answer this question, we inspected the effect of motion adaptations on the future distance of closest approach. This analysis is relevant in the case of collision avoidance because subtle anticipatory behaviors or large last moment adaptations can finally yield the same result upon the final crossing distance. Results showed that collision avoidance is performed collaboratively and the crossing order impacts both the contribution and the strategies used: the participant giving way contributes more than the one passing first to avoid the collision. Both walkers reorient their path but the participant giving way also adapts his speed. Future work is planned to investigate the influence of crossing angle and TTC on adaptations as well as new types of interactions, such as intercepting or meeting tasks. PMID:23665066

  15. Particle creation in a Robertson-Walker Universe revisited

    E-print Network

    F. Pascoal; C. Farina

    2007-01-04

    We reanalyze the problem of particle creation in a 3+1 spatially closed Robertson-Walker space-time. We compute the total number of particles produced by this non-stationary gravitational background as well as the corresponding total energy and find a slight discrepancy between our results and those recently obtained in the literature

  16. Automated Adaptive Support for Peer Tutoring Erin Walker

    E-print Network

    tutors for collaboration (Development 1) and the improvement of automated assessment of peer tutor chatAutomated Adaptive Support for Peer Tutoring Erin Walker October 2010 CMU-HCII-10-107 Human, intelligent tutoring systems, reciprocal peer tutoring, computer-supported collaborative learning

  17. 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)

  18. 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.

  19. 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...

  20. SOIL MOISTURE ESTIMATION USING REMOTE SENSING Jeffrey Walker1

    E-print Network

    Walker, Jeff

    SOIL MOISTURE ESTIMATION USING REMOTE SENSING Jeffrey Walker1 and Paul Houser2 1 Lecturer, Dept Sciences Branch, NASA Goddard Space Flight Center, Maryland, USA Abstract Knowledge of soil moisture high spatial and temporal variability. To overcome the land surface model limits on soil moisture

  1. 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.

  2. An Archaeological Survey for the Walker County Special Utility District Water System Improvement Project in Central Walker County Texas 

    E-print Network

    Moore, William

    2015-07-07

    A Phase I archaeological survey of a water line segment (1.5 miles) in central Walker County, Texas was performed on June 22, 2005 by Brazos Valley Research Associates under Texas Antiquities Permit 3765 with William E. Moore the Principal...

  3. Velocimetry of cathode particles in a magnetoplasmadynamic thruster discharge J. Walker, S. Langendorf, M. Walker, K. Polzin, and A. Kimberlin

    E-print Network

    Walker, Mitchell

    Velocimetry of cathode particles in a magnetoplasmadynamic thruster discharge plasma J. Walker, S and physical processes Phys. Plasmas 19, 073107 (2012); 10.1063/1.4737098 Self-heated hollow cathode discharge, 073513 (2015) Velocimetry of cathode particles in a magnetoplasmadynamic thruster discharge plasma J

  4. Last Glacial Maximum's effect on the Walker circulation

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-10-01

    Over the tropical Pacific Ocean the Walker circulation is an atmospheric flow pattern that runs parallel to the equator, with ascending motion over the western Pacific and a horizontal tropospheric return flow that carries air back to the east. Scientists predict that the Walker circulation will weaken with global warming through a mechanism known as the Held, Soden, and Vecchi (HSV) mechanism. According to this system, as surface ocean temperatures increase, atmospheric humidity and precipitation rates will also increase. Conversely, as surface ocean temperatures decrease, atmospheric humidity and local precipitation will decrease. Humidity levels change much more easily than precipitation rates; as temperatures rise, this disparity leads to a decrease in vertical air motion as the atmosphere tries to maintain a balanced flow of air. If temperatures fall, vertical air motion will increase. Although the HSV mechanism is a robust feature of climate models, its observed sensitivity to changing temperatures remains uncertain.

  5. Dandy-Walker syndrome studied by computed tomography and pneumoencephalography

    SciTech Connect

    Masdeu, J.C.; Dobben, G.D.; Azar-Kia, B.

    1983-04-01

    Based on air studies, some authors have disputed the ability of computed tomography (CT) to diagnose posterior fossa cysts. The authors correlated the pneumoencephalographic, CT, and pathological findings in 4 patients with classic Dandy-Walker syndrome. Three cases had been misdiagnosed as retrocerebellar arachnoid cysts because the fourth ventricle was incorrectly considered normal on brow-up or erect air studies, reflecting the inability of such studies to evaluate an agenetic vermis and deficient posterior medullary velum which are characteristic of Dandy-Walker malformation. Careful correlation with autopsy findings showed that even with complete agenesis of the inferior vermis, if the slit between the cerebellar hemispheres is narrow, the fourth ventricle could be misinterpreted as normal on pneumoencephalography and sagittal CT. Radionuclide studies, a small amount of air, or metrizamide may be needed to determine whether the cyst communicates with the subarachnoid space.

  6. Beyond the Friedmann-Lemaitre-Robertson-Walker Big Bang singularity

    E-print Network

    Ovidiu-Cristinel Stoica

    2012-08-07

    Einstein's equation, in its standard form, breaks down at the Big Bang singularity. A new version, equivalent to Einstein's whenever the latter is defined, but applicable in wider situations, is proposed. The new equation remains smooth at the Big Bang singularity of the Friedmann-Lemaitre-Robertson-Walker model. It is a tensor equation defined in terms of the Ricci part of the Riemann curvature. It is obtained by taking the Kulkarni-Nomizu product between Einstein's equation and the metric tensor.

  7. Intrinsic time in Friedmann-Robertson-Walker universe

    E-print Network

    Pavlov, Alexander

    2016-01-01

    A global intrinsic time in Friedmann - Robertson - Walker models is proportional to a scaling factor of the spatial metric. The aim of the paper is to study an applicability of the intrinsic global time chosen to nearest non-symmetric cases by taking into account linear metric perturbations. Scalar linear perturbations add some corrections to the effective energy density in the Hubble law. The metric vector and tensor perturbations in linear approximation do not influence the intrinsic time.

  8. 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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Cook, Kerry H.; Vizy, Edward K.

    2015-10-01

    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.

  11. Numerical Modeling of Methanogenesis at Walker Ridge, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Glosser, D.; Cook, A.; Malinverno, A.; Daigle, H.

    2014-12-01

    Methane migration is a crucial link between locations of methane generation and natural gas hydrate reservoirs, yet migration mechanisms are poorly understood in the natural environment. In this study, we evaluate constraints on methanogenesis and methane diffusion through the development of a 1-dimensional diagenetic model of the Gulf of Mexico Gas Hydrate Joint Industry Project Site Walker Ridge 313 in the Gulf of Mexico. High saturation gas hydrate was confirmed at Walker Ridge from borehole logs, which measured both high compressional velocity and high resistivity in hydrate-bearing sand layers. Gas hydrate formation depends largely on organic matter concentration and methanogenesis rates. We will test how much organic matter is required to achieve gas hydrate saturations observed at Walker Ridge. Our model will incorporate methane generation around a sand layer as it is moves down through the sediment column. Variable porosity across the sediment column due to early diagenesis and sediment compaction will also be considered. Since methane solubility is higher in finer grained sediments due to smaller pore spaces, gas hydrate will form in the sand layer from methane transported by the relatively slow process of diffusion from finer grained layers. The results of this model are critical to the development of the basin scale simulation of overall methane flux based on the geometry of WR313. The simulation results will improve scientific characterization of how hydrates form and distribute within continental margin sediments.

  12. John F. Walker, US Geological Survey Friday, November 18 , 2011

    E-print Network

    John F. Walker, US Geological Survey Friday, November 18 , 2011 3:30 p.m. RAWLS Hall, room 1011 P U R D U E W AT E R C O M M U N I T Y A N D P U R D U E C L I M AT E C H A N G E R E S E A R C H C E N T E R Estimating climate change impacts on streamflow in the Lake Michigan basin using the USGS PRMS

  13. Automatic Liver Segmentation Using the Random Walker Algorithm

    NASA Astrophysics Data System (ADS)

    Maier, F.; Wimmer, A.; Soza, G.; Kaftan, J. N.; Fritz, D.; Dillmann, R.

    In this paper we present a new method for fully automatic liver segmentation in computed tomography images. First, an initial set of seed points for the random walker algorithm is created. In this context, voxels belonging to air, fat tissue and ribcage are labeled as background. Furthermore, depending on the shape of the ribcage and voxel intensities, several seed points inside the liver are automatically selected as foreground. This seed mask is then used to initialize the segmentation algorithm. Our method was successfully tested on data of 22 patients.

  14. Field-dependent symmetries in Friedmann-Robertson-Walker models

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sudhaker

    2015-05-01

    We consider effective actions of the cosmological Friedmann-Robertson-Walker (FRW) models and discuss their fermionic rigid BRST invariance. Further, we demonstrate the finite field-dependent BRST transformations as a limiting case of continuous field-dependent BRST transformations described in terms of continuous parameter ?. The Jacobian under such finite field-dependent BRST transformations is computed explicitly, which amounts an extra piece in the effective action within functional integral. We show that for a particular choice of a parameter the finite field-dependent BRST transformation maps the generating functional for FRW models from one gauge to another.

  15. 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. PMID:15718465

  16. Finite perturbations on perfect fluid Friedmann-Robertson-Walker models

    SciTech Connect

    Diaz, M.C.; Gleiser, R.J.; Pullin, J.A.

    1989-04-01

    This paper analyzes the behavior of a family of finite exact perturbations of Friedmann-Robertson-Walker cosmologies constructed with the inverse scattering technique of Belinskii and Zakharov (1978). The application of this method in a five-dimensional spacetime with a massless scalar field and a subsequent Kaluza-Klein dimensional reduction makes it possible to construct models with perfect fluid material content in four dimensions. The behavior of the energy momentum and Weyl tensors are studied as characterizations of the gravitational and material behaviors. The important case of solitonic perturbations on de Sitter backgrounds is also treated. 45 refs.

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

    USGS Publications Warehouse

    U.S. Geological Survey

    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.

  18. 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 evapotranspiration station in a saltcedar grove, measurements indicated a possible decrease in evapotranspiration of about 50 percent due to defoliation of the saltcedar by the saltcedar leaf beetle. Total evapotranspiration from the evapotranspiration units identified in the Lower Walker River basin was about 231,000 acre-feet per year (acre-ft/yr). Of this amount, about 45,000 acre-ft/yr originated from direct precipitation, resulting in net evapotranspiration of about 186,000 acre-ft/yr. More than 80 percent of net evapotranspiration in the Lower Walker River basin was through evaporation from Walker Lake. Total evaporation from Walker Lake was about 161,000 acre-ft/yr and net evaporation was about 149,000 acre-ft/yr. Some previous estimates of evaporation from Walker Lake based on water-budget analysis actually represent total evaporation minus ground-water inflow to the lake. Historical evaporation rates determined on the basis of water budget analysis were less than the evaporation rate measured directly during this study. The difference could represent ground-water inflow to Walker Lake of 16,000 to 26,000 acre-ft/yr or could indicate that ground-water inflow to Walker Lake is decreasing over time as the lake perimeter recedes.

  19. 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.

  20. 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.

  1. Ground reaction forces of Olympic and World Championship race walkers.

    PubMed

    Hanley, Brian; Bissas, Athanassios

    2016-02-01

    Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p < .001), resulting in a flattened profile. Athletes with narrower stride widths experienced reduced peak braking forces (r = .49, p = .046), peak propulsive forces (r = .54, p = .027), peak medial forces (r = .63, p = .007) and peak vertical push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency. PMID:25429613

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

    PubMed

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

    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

  3. 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…

  4. 77 FR 54567 - Submission for OMB Review; Comment Request: Requirements for Baby-Bouncers and Walker-Jumpers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-05

    ...Review; Comment Request: Requirements for Baby-Bouncers and Walker-Jumpers AGENCY...of information in the requirements for baby-bouncers and walker-jumpers in regulations...SUPPLEMENTARY INFORMATION: A. Requirements for Baby-Bouncers and Walker-Jumpers One...

  5. Multiple phases and vicious walkers in a wedge

    NASA Astrophysics Data System (ADS)

    Delfino, Gesualdo; Squarcini, Alessio

    2015-12-01

    We consider a statistical system in a planar wedge, for values of the bulk parameters corresponding to a first order phase transition and with boundary conditions inducing phase separation. Our previous exact field theoretical solution for the case of a single interface is extended to a class of systems, including the Blume-Capel model as the simplest representative, allowing for the appearance of an intermediate layer of a third phase. We show that the interfaces separating the different phases behave as trajectories of vicious walkers, and determine their passage probabilities. We also show how the theory leads to a remarkable form of wedge covariance, i.e. a relation between properties in the wedge and in the half plane, which involves the appearance of self-Fourier functions.

  6. Pauli-Fierz gravitons on Friedmann-Robertson-Walker background

    NASA Astrophysics Data System (ADS)

    Grisa, Luca; Sorbo, Lorenzo

    2010-03-01

    We derive the Hamiltonian describing Pauli-Fierz massive gravitons on a flat Friedmann-Robertson-Walker (FRW) cosmology in a particular, non-generic effective field theory. The cosmological evolution is driven by a scalar field ? with an arbitrary potential V(?). The model contains two coupled scalar modes, corresponding to the fluctuations of ? and to the propagating scalar component of the Pauli-Fierz graviton. In order to preserve the full gauge invariance of the massless version of the theory, both modes have to be taken into account. We canonically normalize the Hamiltonian and generalize the Higuchi bound to FRW backgrounds. We discuss how this bound can set limits on the value of the Pauli-Fierz mass parameter. We also observe that on a generic FRW background the speed of propagation of the scalar mode of the graviton is always smaller than the speed of light.

  7. Random Walker Ranking for NCAA Division I-A Football

    E-print Network

    Callaghan, T; Mucha, P J; Callaghan, Thomas; Porter, Mason A.; Mucha, Peter J.

    2003-01-01

    We develop a one-parameter family of ranking systems for NCAA Division I-A football teams based on a collection of voters, each with a single vote, executing independent random walks on a network defined by the teams (vertices) and the games played (edges). The virtue of this class of ranking systems lies in the simplicity of its explanation. We discuss the statistical properties of the randomly walking voters and relate them to the community structure of the underlying network. We compare the results of these rankings for recent seasons with Bowl Championship Series standings and component rankings. To better understand this ranking system, we also examine the asymptotic behaviors of the aggregate of walkers. Finally, we consider possible generalizations to this ranking algorithm.

  8. Effective Translational Diffusion of Nanorotors as Rotary Powered Random Walkers

    NASA Astrophysics Data System (ADS)

    Nourhani, Amir; Lammert, Paul; Borhan, Ali; Crespi, Vincent

    2012-11-01

    The coupling of the orientational stochastic dynamics and rotary powered dynamics at different dimensions leads to an effective translational diffusion of a rotary powered random walker. In a conventional nanorotor system, moving in two-dimension close to a substrate, the one-dimensional orientational stochastic dynamics couples to the rotary deterministic motion and leads to an effective two-dimensional translational diffusion, which is chiral in short to medium time scales. If a nanorotor can have three-dimensional dynamics, an emergent three-dimensional effective diffusion would be the outcome of the coupling between three one-dimensional orientational stochastic processes and a two-dimensional deterministic rotation in the plane of motion. Such effective diffusion processes are a property of nanoscale where the deterministic and stochastic dynamics are both significant.

  9. Emplacement of Basaltic Lava Flows: the Legacy of GPL Walker

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.

    2005-12-01

    Through his early field measurements of lava flow morphology, G.P.L. Walker established a framework for examination of the dynamics of lava flow emplacement that is still in place today. I will examine this legacy as established by three early papers: (1) his 1967 paper, where he defined a relationship between the thickness of recent Etna lava flows and the slope over which they flowed, a relationship that he ascribed to lava viscosity; (2) his 1971 paper, which defined a relationship between lava flux and the formation of simple and compound flow units that he used to infer high effusion rates for the emplacement of some flood basalt lavas; and (3) his often-cited 1973 paper, which related the length of lava flows to their average effusion rate. These three papers, all similar in their basic approach of using field measurements of lava flow morphology to extract fundamental relationships between eruption conditions (magma flux and rheology) and emplacement style (flow length and thickness), firmly established the relationship between flow morphology and emplacement dynamics that has since been widely applied not only to subaerial lava flows, but also to the interpretation of flows in submarine and planetary environments. Important extensions of these concepts have been provided by improved field observation methods, particularly for analysis of flowing lava, by laboratory measurements of lava rheology, by the application of analog experiments to lava flow dynamics, and by steady improvement of numerical techniques to model the flow of lava over complex terrain. The real legacy of G.P.L. Walker's field measurement approach, however, may lie in the future, as new topographic measurement techniques such as LIDAR hold exciting promise for truly quantitative analysis of lava flow morphologies and their relationship to flow dynamics.

  10. 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

  11. X-15 #2 with test pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Joe Walker is seen here after a flight in front of the X-15 #2 (56-6671) rocket-powered research aircraft. Joseph A. Walker was a Chief Research Pilot at the NASA Dryden Flight Research Center during the mid-1960s. He joined NACA in March 1945, and served as project pilot at the Edwards flight research facility on such pioneering research projects as the D-558-1, D-558-2, X-1, X-3, X-4, X-5, and the X-15. He also flew programs involving the F-100, F-101, F-102, F-104, and the B-47. Walker made the first NASA X-15 flight on March 25, 1960. He flew the research aircraft 24 times and achieved its highest altitude. He attained a speed of 4,104 mph (Mach 5.92) during a flight on June 27, 1962, and reached an altitude of 354,200 feet (67.08 miles) on August 22, 1963 (his last X-15 flight). This was one of three flights by Walker that achieved altitudes over 50 miles. Walker was killed on June 8, 1966, when his F-104 collided with the XB-70. The X-15 was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique fairings that extended along the side of the fuselage. The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR-99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was capable of developing 57,000 lb of rated thrust (actual thrust reportedly climbed to 60,000 lb). North American Aviation built three X-15 aircraft for the program. The X-15 research aircraft was developed to provide in-flight information and data on aerodynamics, structures, flight controls, and the physiological aspects of high-speed, high-altitude flight. A follow-on program used the aircraft as a testbed to carry various scientific experiments beyond the Earth's atmosphere on a repeated basis. For flight in the dense air of the usable atmosphere, the X-15 used conventional aerodynamic controls such as rudder surfaces on the vertical stabilizers to control yaw and canted horizontal surfaces on the tail to control pitch when moving in synchronization or roll when moved differentially. For flight in the thin air outside of the appreciable Earth's atmosphere, the X-15 used a reaction control system. Hydrogen peroxide thrust rockets located on the nose of the aircraft provided pitch and yaw control. Those on the wings provided roll control. Because of the large fuel consumption, the X-15 was air launched from a B-52 aircraft at 45,000 ft and a speed of about 500 mph. Depending on the mission, the rocket engine provided thrust for the first 80 to 120 sec of flight. The remainder of the normal 10 to 11 min. flight was powerless and ended with a 200-mph glide landing. Generally, one of two types of X-15 flight profiles was used: a high-altitude flight plan that called for the pilot to maintain a steep rate of climb, or a speed profile that called for the pilot to push over and maintain a level altitude. The X-15 was flown over a period of nearly 10 years--June 1959 to Oct. 1968--and set the world's unofficial speed and altitude records of 4,520 mph (Mach 6.7) and 354,200 ft (over 67 mi) in a program to investigate all aspects of piloted hypersonic flight. Information gained from the highly successful X-15 program contributed to the development of the Mercury, Gemini, and Apollo manned spaceflight programs, and also the Space Shuttle program. The X-15s made a total of 199 flights and were manufactured by North American Aviation. X-15-1, serial number 56-6670, is now located at the National Air and Space Museum, Washington DC. North American X-15A-2, serial number 56-6671, is at the United States Air Force Museum, Wright-Patterson AFB, Ohio. The X-15-3, serial number 56-6672, crashed on 15 November 1967, resulting in the death of Maj. Michael J. Adams.

  12. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch,...

  13. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch,...

  14. ISS Update: Orion Recovery and Rescue Lead Tom Walker - Duration: 5 minutes, 3 seconds.

    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...

  15. 78 FR 37706 - Safety Standards for Infant Walkers and Infant Swings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ...standards for numerous durable infant or toddler products, including infant walkers and...safety standards for durable infant or toddler products. The law requires that these...statute, the term ``durable infant or toddler product'' explicitly includes...

  16. Exact solutions of the Dirac equation in Robertson-Walker space-time

    E-print Network

    Xin-Bing Huang

    2005-01-26

    The covariant Dirac equation in Robertson-Walker space-time is studied under the comoving coordinates. The exact forms of the spatial factor of wave function are respectively acquired in closed, spatially flat, and open universes.

  17. ISS Update: Astronaut Shannon Walker â?? 07.17.2012 - Duration: 19 minutes.

    NASA Video Gallery

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

  18. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790 Cane, crutch, and walker tips and pads. (a)...

  19. 21 CFR 890.3790 - Cane, crutch, and walker tips and pads.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3790 Cane, crutch, and walker tips and pads. (a)...

  20. 50. OVERALL VIEW OF LOWER MAIN STREET, WITH M.M. WALKER ...

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

    50. OVERALL VIEW OF LOWER MAIN STREET, WITH M.M. WALKER COMPANY WAREHOUSE IN LEFT FOREGROUND AND THOMAS J. MULGREW COMPANY BUILDING IN RIGHT BACKGROUND. VIEW TO SOUTHEAST. - Dubuque Commercial & Industrial Buildings, Dubuque, Dubuque County, IA

  1. 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.

  2. 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

  3. 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.

  4. Motor properties from persistence: a linear molecular walker lacking spatial and temporal asymmetry

    NASA Astrophysics Data System (ADS)

    Zuckermann, Martin J.; Angstmann, Christopher N.; Schmitt, Regina; Blab, Gerhard A.; Bromley, Elizabeth HC; Forde, Nancy R.; Linke, Heiner; Curmi, Paul MG

    2015-05-01

    The stepping direction of linear molecular motors is usually defined by a spatial asymmetry of the motor, its track, or both. Here we present a model for a molecular walker that undergoes biased directional motion along a symmetric track in the presence of a temporally symmetric chemical cycle. Instead of using asymmetry, directionality is achieved by persistence. At small load force the walker can take on average thousands of steps in a given direction until it stochastically reverses direction. We discuss a specific experimental implementation of a synthetic motor based on this design and find, using Langevin and Monte Carlo simulations, that a realistic walker can work against load forces on the order of picoNewtons with an efficiency of ?18%, comparable to that of kinesin. In principle, the walker can be turned into a permanent motor by externally monitoring the walker’s momentary direction of motion, and using feedback to adjust the direction of a load force. We calculate the thermodynamic cost of using feedback to enhance motor performance in terms of the Shannon entropy, and find that it reduces the efficiency of a realistic motor only marginally. We discuss the implications for natural protein motor performance in the context of the strong performance of this design based only on a thermal ratchet.

  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. A superspace description of Friedmann-Robertson-Walker models

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sudhaker

    2015-09-01

    We illustrate the cosmological Friedmann-Robertson-Walker (FRW) models realized as gauge theory in the extended configuration space with its Becchi-Rouet-Stora-Tyutin (BRST) invariance up to total derivative. To investigate the model in Batalin-Vilkovisky (BV) formalism the Lagrangian density of the models is further extended by introducing shifted fields corresponding to all fields. The extended Lagrangian density having shifted fields admits more general BRST symmetry (including shift symmetry), called "extended BRST symmetry." In this framework the antighost fields corresponding to the shift symmetry get identified with antifields of BV formulation. Further, we analyse the models on the supermanifold with the help of the additional super (Grassmannian) coordinate ? . Remarkably, we observe that the ? components of superfields naturally produce the gauge-fixing term in tandem with the ghost term of the effective Lagrangian density. Furthermore, we show that the quantum master equation of the BV quantization method can be translated to have a superfield structure for the FRW models.

  8. 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.

  9. 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.

  10. 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. Depth to bedrock in the lower Walker River basin ranges from about 900 to 2,000 feet. The average hydraulic conductivity of the alluvial aquifer in the lower Walker River basin is 10-30 feet per day, except where comprised of fluvial sediments. Fluvial sediments along the Walker River have an average hydraulic conductivity of 70 feet per day. Subsurface flow was estimated to be 2,700 acre-feet per year through Double Spring. Subsurface discharge to Walker Lake was estimated to be 4,400 acre-feet per year from the south and 10,400 acre-feet per year from the north. Groundwater levels and groundwater storage have declined steadily in most of Smith and Mason Valleys since 1960. Groundwater levels around Schurz, Nevada, have changed little during the past 50 years. In the Whisky Flat area south of Hawthorne, Nevada, agricultural and municipal pumpage has lowered groundwater levels since 1956. The water-level decline in Walker Lake since 1882 has caused the surrounding alluvial aquifer to drain and groundwater levels to decline. The Wabuska streamflow-gaging station in northern Mason Valley demarcates the upper and lower Walker River basin. The hydrology of the lower Walker River basin is considerably different than the upper basin. The upper basin consists of valleys separated by consolidated-rock mountains. The alluvial aquifer in each valley thins or pinches out at the downstream end, forcing most groundwater to discharge along the river near where the river is gaged. The lower Walker River basin is one surface-water/groundwater system of losing and gaining reaches from Wabuska to Walker Lake, which makes determining stream losses and the direction and amount of subsurface flow difficult. Isotopic data indicate surface water and groundwater in the lower Walker River basin are from two sources of precipitation that have evaporated. The Walker River, groundwater along the Wassuk Range, and Walker Lake plot along one evaporation line. Groundwater along th

  11. The Conformal Group SO(4,2) and Robertson-Walker Spacetimes

    E-print Network

    Aidan J. Keane; Richard K. Barrett

    1999-07-01

    The Robertson-Walker spacetimes are conformally flat and so are conformally invariant under the action of the Lie group SO(4,2), the conformal group of Minkowski spacetime. We find a local coordinate transformation allowing the Robertson-Walker metric to be written in a manifestly conformally flat form for all values of the curvature parameter k continuously and use this to obtain the conformal Killing vectors of the Robertson-Walker spacetimes directly from those of the Minkowski spacetime. The map between the Minkowski and Robertson-Walker spacetimes preserves the structure of the Lie algebra so(4,2). Thus the conformal Killing vector basis obtained does not depend upon k, but has the disadvantage that it does not contain explicitly a basis for the Killing vector subalgebra. We present an alternative set of bases that depend (continuously) on k and contain the Killing vector basis as a sub-basis (these are compared with a previously published basis). In particular, bases are presented which include the Killing vectors for all Robertson-Walker spacetimes with additional symmetry, including the Einstein static spacetimes and the de Sitter family of spacetimes, where the basis depends on the Ricci scalar R.

  12. 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.

  13. 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. PMID:25359170

  14. 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

  15. X-4 with Pilot Joe Walker, Preflight Briefing

    NASA Technical Reports Server (NTRS)

    1952-01-01

    In this 1952 photograph NACA test pilot Joe Walker (on left) is seen discussing tests points to be flown on the X-4 aircraft with NACA research engineer Donald Bellman. The X-4 Bantam, a single-place, low swept-wing, semi-tailless aircraft, was designed and built by Northrop Aircraft, Inc. It had no horizontal tail surfaces and its mission was to obtain in-flight data on the stability and control of semi-tailless aircraft at high subsonic speeds. The Northrop X-4, Bantam, was a single-place, swept-wing, semi-tailless airplane designed and built to investigate that configuration at transonic speeds (defined as speeds just below and just above the speed of sound, but in this case, the testing was done primarily at just below the speed of sound). The hope of some aerodynamicists was that eliminating the horizontal tail would also do away with stability problems at transonic speeds resulting from the interaction of supersonic shock waves from the wings and the horizontal stabilizers. Northrop Aircraft, Inc. built two X-4 aircraft, the first of which proved to be mechanically unsound. However, ship number 2, with a thicker trailing edge on the wings and elevon, was very reliable. Ship 1 was then grounded and used as parts for ship 2. While being tested from 1950 to 1953 at the NACA High-Speed Flight Research Station (predecessor of today's NASA Dryden Flight Research Center, Edwards, California), the X-4's semi-tailless configuration exhibited inherent longitudinal stability problems (porpoising) as it approached the speed of sound. The X-4 was a small twinjet-engine airplane that had no horizontal tail surfaces, depending instead on combined elevator and aileron control surfaces (called elevons) for control in pitch and roll attitudes. Data gathered from the aircraft's blunt elevon research were helpful in the design of the Bell X-2, which had ailerons with blunted trailing edges. The NACA X-4 program also provided substantial data on the interactions of combined pitching, rolling, and yawing motions. This interaction was soon to become critical to upcoming high-performance military fighters. The X-4, ship 2, flew 82 research flights from 1950 to 1953. With a minimal lift-to-drag ratio of less than 3, the X-4 performance was similar to the soon-to-be-developed X-15. With this similarity in mind, NACA conducted approach and landing studies of X-15-generation aircraft using the X-4. The X-4, retired in 1954, ended its days as a pilot trainer.

  16. Wigner rotation via Fermi-Walker transport and relativistic EPR correlations in the Schwarzschild spacetime

    E-print Network

    K. Bakke; C. Furtado; A. M. de M. Carvalho

    2015-04-28

    The Wigner rotation angle for a particle in a circular motion in the Schwarzschild spacetime is obtained via the Fermi-Walker transport of spinors. Then, by applying the WKB approximation, a possible application of the Fermi-Walker transport of spinors in relativistic EPR correlations is discussed, where it is shown that the spins of the correlated particle undergo a precession in an analogous way to that obtained by Terashima and Ueda [H. Terashima and M. Ueda, Phys. Rev. A {\\bf69}, 032113 (2004)] via the application of successive infinitesimal Lorentz transformations. Moreover, from the WKB approach, it is also shown that the degree of violation of the Bell inequality depends on the Wigner rotation angle obtained via the Fermi-Walker transport. Finally, the relativistic effects from the geometry of the spacetime and the accelerated motion of the correlated particles is discussed in the nonrelativistic limit.

  17. Wigner rotation via Fermi-Walker transport and relativistic EPR correlations in the Schwarzschild spacetime

    E-print Network

    Bakke, K; Carvalho, A M de M

    2015-01-01

    The Wigner rotation angle for a particle in a circular motion in the Schwarzschild spacetime is obtained via the Fermi-Walker transport of spinors. Then, by applying the WKB approximation, a possible application of the Fermi-Walker transport of spinors in relativistic EPR correlations is discussed, where it is shown that the spins of the correlated particle undergo a precession in an analogous way to that obtained by Terashima and Ueda [H. Terashima and M. Ueda, Phys. Rev. A {\\bf69}, 032113 (2004)] via the application of successive infinitesimal Lorentz transformations. Moreover, from the WKB approach, it is also shown that the degree of violation of the Bell inequality depends on the Wigner rotation angle obtained via the Fermi-Walker transport. Finally, the relativistic effects from the geometry of the spacetime and the accelerated motion of the correlated particles is discussed in the nonrelativistic limit.

  18. Modern and ancient submarine fans: discussion of papers by Walker and Normark.

    USGS Publications Warehouse

    Nilsen, T.H.

    1980-01-01

    A comment on two papers, by Walker (GeoAbstracts 78E/2328) and Normark (GeoAbstracts 78E/2278), in which attempts were made to synthesize current concepts and models of deep-marine sedimentation for modern and ancient submarine fans. Argues that several important aspects of these papers are misleading - namely, Walker's confusing use of the term 'thick-bedded' for 'proximal', problems introduced by application of the suprafan concept to ancient fan deposits; and unfortunate overemphasis of channeled submarine fan deposits as exploration targets.-after Author

  19. A Phase I Cultural Resources Survey of the Walker County Jail and Office Expansion Area Project 

    E-print Network

    Moore, William

    2015-06-08

    assessment of a 12.82 acre tract on land owned by the County of Walker in central Walker County, Texas (Figure 1). The site area is on a high clay ridge overlooking a low area to the north. The project area is bounded on the north by F.M. Road 2821... of F.M. 149 (Bement et al. 1987:6-5). Between 1700 and 1835 (when native groups had been removed from East Texas), Indians in the area underwent rapid and dramatic changes. The Spanish failed in their efforts to Christianize the Indians of East...

  20. 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.

  1. 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.

  2. Safety Committee Meeting Minutes for September 6, Members present; Randy Walker HMSC/OSU, Dave Johnson, Facilities,

    E-print Network

    Wright, Dawn Jeannine

    , ODF&W, Alena Pribyl, HMSC/OSU/Housing Walker told that OSU campus is working on a plan to address bathrooms. Parker spoke to the flooding issues that frequent the lot in front of ODF&W during winter storms with recommended disaster items that individuals should carry up to the evacuation site. Walker will get a bull

  3. 77 FR 54567 - Submission for OMB Review; Comment Request: Requirements for Baby-Bouncers and Walker-Jumpers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-05

    ..., 2012 (77 FR 3700), the Consumer Product Safety Commission (CPSC or Commission) published a notice in... COMMISSION Submission for OMB Review; Comment Request: Requirements for Baby-Bouncers and Walker-Jumpers... baby-bouncers and walker-jumpers in regulations codified at 16 CFR 1500.18(a)(6) and 1500.86(a)(4)....

  4. 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. He taught for two years at Iowa State and then spent seven years as a Senior Research Officer at Chalk River. It was from this period that his important early contributions to nuclear astrophysics emerged. His research addressed a broad range of problems concerning the origin of the elements, culminating in the publication in 1957 of a discussion of stellar evolution and nucleosynthesis which, together with the paper by E.M. Burbidge, G.F. Burbidge, W.A. Fowler, and F. Hoyle, substantially defined the field of nucleosynthesis as we understand it today. Cameron joined the staff of the NASA Institute for Space Studies in New York and served as a Senior Scientist from 1961 to 1966, then continued on to the Belfer Graduate School of Science of Yeshiva University in New York, prior to moving to Harvard. Working with an increasing number of graduate students and postdocs, Cameron continued his studies in nuclear physics, concentrating on building systematics of nuclear mass formulae, nuclear level densities, thermonuclear reaction rates, and weak interaction rates. These nuclear systematics, coupled to early calculations of supernova explosions, enabled the first detailed numerical investigations of explosive nucleosynthesis from which the identification of 56Ni as the dominant product emerged. During these years, Cameron's research activities and interests expanded considerably to encompass broad areas of space physics, including specifically the origin of the Solar System. Notable here is the significant role he played in the early formulation and development of the impact theory for the origin of the Moon. This theory posits - and early numerical simulations by Cameron and his collaborators confirmed - that the collision of a large, Mars sized object with the Earth early in its history yields debris from which the Moon can coalesce, and can account for both an iron-depleted Moon and the masses and angular momentum of the Earth-Moon system. Cameron was an extremely imaginative and productive scientist whose contributions profoundly influenced many areas of resear

  5. Moebius syndrome with Dandy-Walker variant and agenesis of corpus callosum

    PubMed Central

    John, Jomol Sara; Vanitha, R.

    2013-01-01

    Moebius syndrome is a rare congenital neurological disorder. The most frequent mode of presentation is facial diplegia with bilateral lateral rectus palsy, but there are variations. Here, we report a rare case of Moebius syndrome in a 15-month-old child with unilateral facial palsy, bilateral abducens nerve palsy with Dandy Walker variant, and complete agenesis of corpus callosum. PMID:24470815

  6. Variables of the Touch Technique that Influence the Safety of Cane Walkers

    ERIC Educational Resources Information Center

    Bongers, Raoul M.; Schellingerhout, Roelef; van Grinswen, Roland; Smitsman, Ad W.

    2002-01-01

    This study evaluated variables that determined the safety of 15 cane users who were using the touch technique. The results showed that none of the walkers used a touch technique as described and recommended in the literature, that the detection of obstacles was related mainly to the height of the cane tip during the sweep, and that the early…

  7. HEAT RECOVERY IN BUILDING ENVELOPES Max H. Sherman and Iain S. Walker

    E-print Network

    1 LBNL 47329 HEAT RECOVERY IN BUILDING ENVELOPES Max H. Sherman and Iain S. Walker Energy formula may produce an unreasonably high contribution because of heat recovery within the building envelope. Previous laboratory and simulation research has indicated that such heat transfer between

  8. 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…

  9. Greg Walker, PhD Regius Professor of Rhetoric and English Literature

    E-print Network

    Edinburgh, University of

    Realities: Brave New World and Nineteen Eighty-Four DR ELSA BOUET English Literature, UniversityDEAN Greg Walker, PhD Regius Professor of Rhetoric and English Literature University of Edinburgh ASSOCIATE DEANS Robert Irvine, PhD Vassiliki Kolocotroni, PhD English Literature English Literature

  10. Improved Wafer-level Spatial Analysis for IDDQ Limit Setting Sagar Sabade D. M. H. Walker

    E-print Network

    Walker, Duncan M. "Hank"

    Improved Wafer-level Spatial Analysis for IDDQ Limit Setting Sagar Sabade D. M. H. Walker methodology for estimating the upper bound on the IDDQ of defect free chips by using wafer level spatial data. Such a methodology accounts for the change in IDDQ due to process variations across wafers

  11. Wafer Signature Analysis of IDDQ Test Data Sagar S. Sabade D. M. H. Walker

    E-print Network

    Walker, Duncan M. "Hank"

    Wafer Signature Analysis of IDDQ Test Data Sagar S. Sabade D. M. H. Walker Department of Computer. The concept of wafer signature is proposed. A wafer signature is obtained by sorting all IDDQ readings on a wafer for a vector. A break or jump in the wafer signature is considered to indicate defective chips

  12. Infrastructure of the Gemini Observatory Control System K. K. Gillies and S. Walker

    E-print Network

    Infrastructure of the Gemini Observatory Control System K. K. Gillies and S. Walker Gemini 8m Telescopes Project, 950 N. Cherry Ave., Tucson, AZ, 85719 Gemini Preprint # 31 #12; Infrastructure software infrastructure is required to support this comprehensive approach. New software technologies

  13. Infrastructure of the Gemini Observatory Control System K. K. Gillies and S. Walker

    E-print Network

    Infrastructure of the Gemini Observatory Control System K. K. Gillies and S. Walker Gemini 8m Telescopes Project, 950 N. Cherry Ave., Tucson, AZ, 85719 Gemini Preprint # 31 #12;Infrastructure software infrastructure is required to support this comprehensive approach. New software technologies

  14. Surveying The TeV Sky With Milagro G. P. Walker for the Milagro Collaboration

    E-print Network

    California at Santa Cruz, University of

    Surveying The TeV Sky With Milagro G. P. Walker for the Milagro Collaboration Los Alamos National highly variable or are extended. Milagro is such a TeV detector and has performed the deepest surveyV. OBSERVATIONS An all-sky survey was conducted with data collected between July 2000 and March 2006, using the A4

  15. Comparative Analysis of Probabilistic Models for Activity Recognition with an Instrumented Walker

    E-print Network

    Poupart, Pascal

    Comparative Analysis of Probabilistic Models for Activity Recognition with an Instrumented Walker a retirement community is presented. 1 Introduction Improving the quality of life of the ever increasing el mobility for these individuals have a significant impact on the quality of their life. Devices

  16. USDA Farm Service Agency Disaster Assistance1 Michael T. Olexa and Travis Walker2

    E-print Network

    Hill, Jeffrey E.

    , and Travis Walker, student, Levin College of Law, University of Florida, Gainesville, FL 32611. Note information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status

  17. Dynamics with Infinitely Many Time Derivatives in Friedmann-Robertson-Walker Background and Rolling Tachyon

    E-print Network

    Liudmila Joukovskaya

    2008-07-14

    Open string field theory in the level truncation approximation is considered. It is shown that the energy conservation law determines existence of rolling tachyon solution. The coupling of the open string field theory action to a Friedmann-Robertson-Walker metric is considered which leads to a new time dependent rolling tachyon solution is presented and possible cosmological consequences are discussed.

  18. Issues in the Effective Use of Walker Problem Behavior Identification Checklist.

    ERIC Educational Resources Information Center

    Reeves, John E.; And Others

    The interrater reliability of the Walker Problem Behavior Identification Checklist subscale scores was examined. An attempt was also made to determine whether the background, experience, or training of the rater-teacher influenced the scores given. Two independent raters, the regular classroom teacher and a teacher of the emotionally disturbed,…

  19. Groupoidification Made Easy John C. Baez, Alexander E. Hoffnung, and Christopher D. Walker

    E-print Network

    Baez, John

    Groupoidification Made Easy John C. Baez, Alexander E. Hoffnung, and Christopher D. Walker ground field). For example, let E be the groupoid of finite sets and bijections. An isomor- phism class of finite sets is just a natural number, so the set of isomorphism classes of objects in E can be identified

  20. Hall Thruster Cluster Operation with a Shared Cathode Mitchell L. R. Walker

    E-print Network

    Walker, Mitchell

    Hall Thruster Cluster Operation with a Shared Cathode Mitchell L. R. Walker and Alec D. Gallimore the operation of the CDT itself [2­4]. The U.S. Air Force Research Laboratory (AFRL), NASA John H. Glenn high-power goal (i.e., the use of smaller Hall thrusters in a propulsion array [5]). Clustering allows

  1. Groupoidification Made Easy John C. Baez, Alexander E. Ho#nung, and Christopher D. Walker

    E-print Network

    Baez, John

    Groupoidification Made Easy John C. Baez, Alexander E. Ho#nung, and Christopher D. Walker other ground field). For example, let E be the groupoid of finite sets and bijections. An isomor­ phism class of finite sets is just a natural number, so the set of isomorphism classes of objects in E can

  2. ACTIVITIES TO ATTRACT HIGH SCHOOL GIRLS TO COMPUTER SCIENCE Susan H. Rodger Ellen L. Walker

    E-print Network

    Rodger, Susan H.

    ACTIVITIES TO ATTRACT HIGH SCHOOL GIRLS TO COMPUTER SCIENCE Susan H. Rodger Ellen L. Walker for high school girls. These hands-on activities and interactive talks, presented mostly by female faculty, undergraduates, and graduate students, showed the girls the wide range of opportuni- ties in the eld of computer

  3. LATERALIZATION OF SOUNDS USING BONE-CONDUCTION HEADSETS Raymond M. Stanley and Bruce N. Walker

    E-print Network

    LATERALIZATION OF SOUNDS USING BONE-CONDUCTION HEADSETS Raymond M. Stanley and Bruce N. Walker, for stimuli delivered through bone-conduction headsets and standard headphones. The results showed that non sounds to listeners through bone conduction by placing vibrators on the skull avoids covering the ears

  4. 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…

  5. Addition spectrum and Koopmans' theorem for disordered quantum dots Paul N. Walker* and Gilles Montambaux

    E-print Network

    Montambaux, Gilles

    Addition spectrum and Koopmans' theorem for disordered quantum dots Paul N. Walker* and Gilles or nearest-neighbor interactions when rs 1. We also show that Koopmans' approximation to the addition single-particle theory. Koopmans' theorem1 states that the single-particle SCHF energy levels describe

  6. Navigating Blind People with a Smart Walker Andreas Wachaja* Pratik Agarwal* Mathias Zink* Miguel Reyes Adame

    E-print Network

    Teschner, Matthias

    Navigating Blind People with a Smart Walker Andreas Wachaja* Pratik Agarwal* Mathias Zink* Miguel is a major challenge for blind people. The most popular, conventional navigation aids such as white canes to assist blind people in complex navigation tasks as they can provide information about obstacles

  7. Cloning, purification and crystallization of a Walker-type Pyrococcus abyssi ATPase family member

    SciTech Connect

    Uhring, Muriel; Bey, Gilbert; Lecompte, Odile; Cavarelli, Jean; Moras, Dino; Poch, Olivier

    2005-10-01

    The Walker-type ATPase PABY2304 of P. abyssi has been cloned, overexpressed, purified and crystallized. X-ray diffraction data from selenomethionine-derivative crystals have been collected to 2.6 Å. The structure has been solved by MAD techniques. Several ATPase proteins play essential roles in the initiation of chromosomal DNA replication in archaea. Walker-type ATPases are defined by their conserved Walker A and B motifs, which are associated with nucleotide binding and ATP hydrolysis. A family of 28 ATPase proteins with non-canonical Walker A sequences has been identified by a bioinformatics study of comparative genomics in Pyrococcus genomes. A high-throughput structural study on P. abyssi has been started in order to establish the structure of these proteins. 16 genes have been cloned and characterized. Six out of the seven soluble constructs were purified in Escherichia coli and one of them, PABY2304, has been crystallized. X-ray diffraction data were collected from selenomethionine-derivative crystals using synchrotron radiation. The crystals belong to the orthorhombic space group C2, with unit-cell parameters a = 79.41, b = 48.63, c = 108.77 Å, and diffract to beyond 2.6 Å resolution.

  8. 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)

  9. On Three and Four Vicious Walkers William Y. C. Chen1

    E-print Network

    Chen, Bill

    from Gessel's theorem. Keywords: vicious walkers, watermelon, Catalan numbers, Ballot numbers common points. In particular, a watermelon of length n is a configuration consisting of r chains #12;(n, k), (n, k + 2), . . . , (n, k + 2r - 2) for some k. In other words, a watermelon is a vicious

  10. Strengthening of the Walker circulation under globalwarming in an aqua-planet general circulation model simulation

    NASA Astrophysics Data System (ADS)

    Li, Tim; Zhang, Lei; Murakami, Hiroyuki

    2015-11-01

    Most climate models project a weakening of theWalker circulation under global warming scenarios. It is argued, based on a global averaged moisture budget, that this weakening can be attributed to a slower rate of rainfall increase compared to that of moisture increase, which leads to a decrease in ascending motion. Through an idealized aqua-planet simulation in which a zonal wavenumber-1 SST distribution is prescribed along the equator, we find that the Walker circulation is strengthened under a uniform 2-K SST warming, even though the global mean rainfall-moisture relationship remains the same. Further diagnosis shows that the ascending branch of the Walker cell is enhanced in the upper troposphere but weakened in the lower troposphere. As a result, a "double-cell" circulation change pattern with a clockwise (anti-clockwise) circulation anomaly in the upper (lower) troposphere forms, and the upper tropospheric circulation change dominates. The mechanism for the formation of the "double cell" circulation pattern is attributed to a larger (smaller) rate of increase of diabatic heating than static stability in the upper (lower) troposphere. The result indicates that the future change of the Walker circulation cannot simply be interpreted based on a global mean moisture budget argument.

  11. Empirical Studies in Discourse Marilyn A. Walker \\Lambda & Johanna D. Moore y

    E-print Network

    Moore, Johanna D.

    dialogue and textual corpora available; and improvements in component technologies and tools for building&T Labs Research, 600 Mountain Ave. 2D­441, Murray Hill, NJ. 07974, walker@research.att.com y Computer are features of the task that are fixed from the system designer's viewpoint, system factors which reflect

  12. 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

  13. Regional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening*

    E-print Network

    Xie, Shang-Ping

    in the tropical eastern Pacific and western Indian Ocean than in the tropical western Pacific and eastern IndianRegional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening* HIROKI TOKINAGA, SHANG-PING XIE, AND AXEL TIMMERMANN International Pacific Research Center, SOEST

  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..., with two modifications to make the standard more stringent. 77 FR 66703. ASTM notified CPSC that the... adverse comment. See 60 FR 43108 (August 18, 1995). Thus, the Commission is publishing this rule as...

  15. 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)

  16. Sleep-Dependent Memory Processing Matthew P. Walker, PhD

    E-print Network

    Walker, Matthew P.

    REVIEW Sleep-Dependent Memory Processing Matthew P. Walker, PhD While the functions of sleep remain largely unknown, one exciting hypothesis is that sleep contributes importantly to processes of memory supporting this role of sleep in what is becoming known as sleep- dependent memory processing. This review

  17. Informing Eclipse API Production and Consumption Reid Holmes and Robert J. Walker

    E-print Network

    Robillard, Martin

    Informing Eclipse API Production and Consumption Reid Holmes and Robert J. Walker Laboratory, Canada rtholmes,rwalker@cpsc.ucalgary.ca ABSTRACT Application programming interfaces (APIs) inform application de- velopers as to the functionality provided by a library and how to interact with it. APIs

  18. The Northern Walker Lane Refraction Experiment: Pn Arrivals and the Northern Sierra Nevada Root

    E-print Network

    1 The Northern Walker Lane Refraction Experiment: Pn Arrivals and the Northern Sierra Nevada Root and Dept. of Geological Sciences University of Nevada 174, Reno, NV 89557 Phone 775-784-4219; fax 775 a new crustal refraction profile from Battle Mountain, Nevada across western Nevada, the Reno area, Lake

  19. The northern Walker Lane refraction experiment: Pn arrivals and the northern Sierra Nevada root

    E-print Network

    The northern Walker Lane refraction experiment: Pn arrivals and the northern Sierra Nevada root of Nevada, Mackay School of Earth Sciences and Engineering, Reno, NV 89557, USA b Optim LLC, Reno, NV, USA, Nevada across western Nevada, the Reno area, Lake Tahoe, and the northern Sierra Nevada Mountains

  20. Effect of secondary electron emission on the plasma sheath S. Langendorf and M. Walker

    E-print Network

    Walker, Mitchell

    Effect of secondary electron emission on the plasma sheath S. Langendorf and M. Walker Citation. A 30, 051303 (2012); 10.1116/1.4737615 Dependence of ion sheath collapse on secondary electron emission.1063/1.1755850 Effect of secondary electron emission on sheath potential in an electron cyclotron resonance plasma J

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. A Test of Amino Acid Reversibility Nick G.C. Smith, Adam Eyre-Walker

    E-print Network

    Eyre-Walker, Adam

    A Test of Amino Acid Reversibility Nick G.C. Smith, Adam Eyre-Walker Centre for the Study no evidence to reject the assumption of reversibility in protein evolution. Key words: Amino acid evolution the evolution of proteins, it is generally assumed that the number of substitutions from amino acid X to amino

  7. Interinstrument Consistency of the Yamax Digi-Walker Pedometer in Elementary School-Aged Children

    ERIC Educational Resources Information Center

    Barfield, J. P.; Rowe, David A.; Michael, Timothy J.

    2004-01-01

    A pedometer is a practical, inexpensive tool used to measure physical activity. Bassett et al. (1996) found that interinstrument consistency of the Yamax Digi-Walker was higher than four other pedometers when measuring distance walked in adults. The purpose of this study was to investigate the interinstrument consistency of the Yamax pedometer in…

  8. Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers.

    PubMed

    Zhang, Songning; Clowers, Kurt G; Powell, Douglas

    2006-12-01

    Short-leg walking boots offer several advantages over traditional casts. However, their effects on ground reaction forces (GRF) and three-dimensional (3D) biomechanics are not fully understood. The purpose of the study was to examine 3D lower extremity kinematics and joint dynamics during walking in two different short-leg walking boots. Eleven (five females and six males) healthy subjects performed five level walking trials in each of three conditions: two testing boot conditions, Gait Walker (DeRoyal Industries, Inc.) and Equalizer (Royce Medical Co.), and one pair of laboratory shoes (Noveto, Adidas). A force platform and a 6-camera Vicon motion analysis system were used to collect GRFs and 3D kinematic data during the testing session. A one-way repeated measures analysis of variance (ANOVA) was used to evaluate selected kinematic, GRF, and joint kinetic variables (p<0.05). The results revealed that both short-leg walking boots were effective in minimizing ankle eversion and hip adduction. Neither walker increased the bimodal vertical GRF peaks typically observed in normal walking. However, they did impose a small initial peak (<1BW) earlier in the stance phase. The Gait Walker also exhibited a slightly increased vertical GRF during midstance. These characteristics may be related to the sole materials/design, the restriction of ankle movements, and/or the elevated heel heights of the tested walkers. Both walkers appeared to increase the demand on the knee extensors while they decreased the demand of the knee and hip abductors based on the joint kinetic results. PMID:16414263

  9. Deformation Along the Wassuk Range of the Northern Walker Lane, Nevada

    NASA Astrophysics Data System (ADS)

    Ucarkus, G.; Dong, S.; Wesnousky, S. G.; Maloney, J. M.; Kent, G.; Driscoll, N. W.

    2013-12-01

    Walker Lake is a fault-controlled basin along the Wassuk Range front in the Walker Lane shear zone. Geologic observations suggest that motion along the range-bounding faults of Walker Lake is predominately dip-slip. Nevertheless, geodetic measurements indicate that the right-lateral strike-slip motion is equal to or greater than the extensional component of slip. New terrestrial and lacustrine observations adjacent to the Wassuk Range and within Walker Lake show the presence of a fault zone outboard of the Wassuk rangefront with a trend ~N30°W. The remnant shorelines of pluvial Lake Lahontan that reached its highstand about ~15,500 yr B.P. are displaced between about ~12-15 m and lead to a right-lateral slip rate estimate of the fault approaching 1 mm/yr or greater. A record of strike-slip displacement is also preserved in high quality CHIRP seismic profiles acquired in Walker Lake about 15 km south of the observed shoreline offsets. The data image faulting and intense folding. The ~N30°E trend of the offshore strike-slip faults suggests that they correspond to Riedel shears off the main strike-slip fault mapped on land. Lake chronology based on core data allows us to constraint the cessation of the strike-slip deformation at ~10.5 ka BP. Sediment divergence observed along the western portion of the lake sediments records tectonic deformation along the Wassuk rangefront; this most recent episode of dip-slip deformation is dated as 3000 yrs BP. Our observations from the lacustrine CHRIP survey and terrestrial LIDAR measurements show partitioning of oblique deformation between subparallel normal and strike-slip of Wassuk Range. These observations begin to reconcile what has been a mismatch between geodetically predicted deformation rates and geological fault slip rate studies along the Wassuk rangefront.

  10. 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

  11. 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

  12. 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. While measuring known systems for orbital analysis, he discovered 22 pairs (mostly additional components to these systems) and moving pairs, and his highlighting the rapid motion of these systems resulted in them being placed on many programs and led to the more definitive orbits of today. As a staff member of the Flagstaff Station, Dick was, for over 30 years, one of the principal observers on the 61-inch parallax program. He also ventured into other areas of astronomy, including planetary systems. He is credited with discovering the moon of Saturn, Epimetheus, in December 1966, with the USNO Flagstaff Station 61-inch Kaj Strand Astrometric Reflector. He also obtained photographic plates to determine accurate positions of the outer planets for the Voyager 2 approaches to Uranus in 1986 and Neptune in 1989. It is interesting to note that Dick's career in observational astronomy spanned three different eras of astronomical instrumentation and technique. He began his career doing eyeball astronomy, using a filar micrometer to measure double star separations. Photographic astronomy then became dominant and he took many thousands of plates. During the last ten years of his career, electronic cameras, primarily CCDs, replaced photographic plates. He readily adapted to the changing technologies. A man of many interests, Dick was fascinated by the history of astronomy, especially archeoastronomy, as well as Egyptology. He taught himself the language of hieroglyphics. In 1977, having accumulated several weeks of vacation time, he set off on a trek to walk the Nile for 500 miles from Aswan to Cairo. One night, in the town Asyut along the Nile, he was brought into the police station. The local inhabitants found it hard to credit his story that he was simply on a walk and questioned him as a possible Israeli spy. Following his retirement from the Naval Observatory, Dick consulted in a couple of construction projects. He designed the analemma and the skywalk star fields for the Koch Center for Science, Math, and Technology at Deerfield Academy in Massachusetts. He also c

  13. 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.

  14. Impulsive Behavior and Recurrent Major Depression Associated with Dandy-Walker Variant

    PubMed Central

    Kim, Ji Hyun; Kim, Tae Ho; Choi, Young Chil; Chung, Soon-Cheol

    2013-01-01

    Reported herein is a case of recurrent major depression with impulse control difficulty in a 33-year-old man with Dandy-Walker variant. He was diagnosed as having major depressive disorder a year before he presented himself to the authors' hospital, and had a history of three-time admission to a psychiatric unit in the previous 12 months. He was readmitted and treated with sodium valporate 1,500 mg/day, mirtazapine 45 mg/day, and quetiapine 800 mg/day during the three months that he was confined in the authors' hospital, and the symptoms were reduced within three months but remained thereafter. This is the only case so far reporting recurrent depression with impulse control difficulty associated with Dandy-Walker variant. This case implies that any cerebellar lesion may cause the appearance of recurrent depression with impulse control difficulty in major depressive disorder. PMID:24302956

  15. 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%. PMID:24187265

  16. Robertson-Walker fluid sources endowed with rotation characterised by quadratic terms in angular velocity parameter

    E-print Network

    R J Wiltshire

    2003-02-12

    Einstein's equations for a Robertson-Walker fluid source endowed with rotation Einstein's equations for a Robertson-Walker fluid source endowed with rotation are presented upto and including quadratic terms in angular velocity parameter. A family of analytic solutions are obtained for the case in which the source angular velocity is purely time-dependent. A subclass of solutions is presented which merge smoothly to homogeneous rotating and non-rotating central sources. The particular solution for dust endowed with rotation is presented. In all cases explicit expressions, depending sinusoidally on polar angle, are given for the density and internal supporting pressure of the rotating source. In addition to the non-zero axial velocity of the fluid particles it is shown that there is also a radial component of velocity which vanishes only at the poles. The velocity four-vector has a zero component between poles.

  17. The Friedmann-Lemaitre-Robertson-Walker Big Bang singularities are well behaved

    E-print Network

    Ovidiu-Cristinel Stoica

    2015-06-02

    We show that the Big Bang singularity of the Friedmann-Lemaitre-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.

  18. Hadronic Matter in the Robertson-Walker Metric and the Early Universe

    E-print Network

    Ivan E. Cunha; Celso C. Barros Jr

    2015-05-20

    In this work, the Friedman equations for hadronic matter in the Robertson-Walker metric in the early Universe are obtained. We consider the hadronic phase, formed after the hadronization of the quark-gluon plasma, that means times from 10^{-6}s to 1s. The set of equations is derived and the behavior of the system is studied considering one approximate analytical solution.

  19. Semisynthesis and insecticidal activity of arylmethylamine derivatives of the neolignan honokiol against Mythimna separata Walker.

    PubMed

    Yang, Chun; Zhi, Xiaoyan; Xu, Hui

    2015-01-01

    A series of novel arylmethylamine derivatives of honokiol (5a-m) was prepared. Their insecticidal activity was tested against the pre-third-instar larvae of the oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. Compounds 5a, 5b, 5e, 5h, and 5k exhibited insecticidal activity equal to, or higher than, that of the positive control toosendanin. PMID:26023846

  20. 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.

  1. 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

  2. A Model for Supersymmetry — An Extension of the Chen-Walker's Model —

    NASA Astrophysics Data System (ADS)

    Mashiyama, Hiroyuki; Mashiyama, Kazuko

    1999-04-01

    A model for incommensurate transitions proposed by Chen and Walker [Phys. Rev. B 43 (1991) 5634] has been extended to describe a sub-lattice model which possesses supersymmetry. If a zone boundary mode freezes, a superstructure with supersymmetry can appear and may transform into a superstructure without supersymmetry at lower temperature. Although both superstructures belong to the same space group, the transition is either second or first order one with accompanying a definite anomaly in specific heat and susceptibility.

  3. 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…

  4. The Schr\\" odinger picture of the Dirac quantum mechanics on spatially flat Robertson-Walker backgrounds

    E-print Network

    Ion I. Cotaescu

    2007-08-06

    The Schr\\" odinger picture of the Dirac quantum mechanics is defined in charts with spatially flat Robertson-Walker metrics and Cartesian coordinates. The main observables of this picture are identified, including the interacting part of the Hamiltonian operator produced by the minimal coupling with the gravitational field. It is shown that in this approach new Dirac quantum modes on de Sitter spacetimes may be found analytically solving the Dirac equation.

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

    NASA Astrophysics Data System (ADS)

    Stoica, Ovidiu Cristinel

    2015-04-01

    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.

  6. Lifelong exposure to dietary fish oil alters macrophage responses in Walker 256 tumor-bearing rats.

    PubMed

    Bonatto, Sandro J R; Folador, Alessandra; Aikawa, Júlia; Yamazaki, Ricardo K; Pizatto, Nathalia; Oliveira, Heloisa H P; Vecchi, Rodrigo; Curi, Rui; Calder, Philip C; Fernandes, Luiz C

    2004-01-01

    Supplementation of the diet with fish oil (FO) decreases growth of the Walker 256 tumor and decreases the cachexia associated with tumor-bearing. The mechanisms by which FO inhibits tumor growth and cachexia are unknown. Macrophages are very important in host defence against tumors since they produce several anti-tumor agents which in turn have been shown to be modified by dietary FO, but rarely in the setting of tumor bearing and never in relation to lifelong exposure. In this study, we compared the effects of supplementation of the diet of pregnant and lactating rats and subsequent supplementation of the offspring with coconut fat or FO on macrophage activities involved in anti-tumor defence. FO supplementation was able to induce an increase in phagocytosis, in O2-, H2O2, nitric oxide, and TNF-alpha production by macrophages and in lysosomal volume in non-tumor-bearing rats. However, phagocytosis, production of O2- and H2O2 and lysosomal volume were not affected by the FO diet when rats were bearing tumors, although nitric oxide production was higher in these animals. It appears that tumor bearing activates the innate immune system and that dietary FO has little effect on innate immunity in the presence of Walker 256 tumors. Thus, it is still unclear how FO decreases the growth of Walker 256 tumors and the associated cachexia. PMID:15919370

  7. 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.

  8. 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.

  9. 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.

  10. 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 observations. Our analysis focuses initially on probing the inter-model differences in energy fluxes / transports and Walker Circulation response to forcing. We then attempt to identify statistically the El Nino- / La Nina-related ocean heat content variability unique to each model and regress out the associated energy flux, ocean heat transport and Walker response on these shorter time scales for comparison to that of the anthropogenic signals.

  11. Interaction of the Walker Lane and the Cascade Volcanic Arc, Northern California

    NASA Astrophysics Data System (ADS)

    Muffler, L.; Blakely, R.; Clynne, M.

    2008-12-01

    We utilize modern geologic and gravity data sets to examine the interaction between the Walker Lane and the southernmost Cascade Volcanic Arc. The Cascade Volcanic Arc in the Lassen region is the product of eastward subduction of the Juan de Fuca plate beneath the North American plate in northern California. To the southeast, the Walker Lane is a structural zone that takes up ~15-25% of the dextral movement between the Pacific and North American plates. The intersection of these two tectonic features in northeastern California is presumed to migrate northward roughly parallel to the northward migration of the Mendocino Triple Junction. Several workers have inferred that NW-trending dextral faults of the Walker Lane intersect and interact with the southernmost Cascade Volcanic Arc in the Lassen region. In the southernmost Cascade Arc, a pronounced unconformity separates <3.5 Ma volcanic rocks from underlying pre-Tertiary sedimentary and metamorphic rocks. The southern limit of volcanism has contracted northward from 40°7.5' at ~3.5 Ma to 40°22.5' at 0.5--0 Ma. Volcanism along the axis is dominated by volcanic centers---large, long-lived, composite, calc-alkaline edifices erupting the full range of compositions from basaltic andesite to rhyolite. Older volcanic centers (3.5--1 Ma) show no correlation with residual gravity, whereas a negative gravity anomaly (-15 mGal) does coincide with <800 ka focused volcanism at the Lassen Volcanic Center (LVC) and the Caribou Volcanic Field (CVF). The most negative part of this gravity anomaly (-30 mGal) coincides with the LVC, a locus of major silicic volcanism, including a significant caldera eruption at 610 ka and a 300--0 ka silicic domefield. Faults are conspicuous E, SE and N of the LVC, but are nearly absent within the LVC. Faults and gravity gradients SE of the LVC strike ~315°, sub-parallel to Walker Lane trends farther to the SE, whereas vent alignments and gravity gradients north of the LVC strike ~345°. Pronounced linear alignments of volcanic vents just east of the LVC suggest significant ENE extension at that latitude. We conclude that the gravity low encompassing the LVC and the CVF reflects the presence during the last 800 ka of a large, crustal-scale tensional regime. This regime was most pronounced under the LVC, where enhanced basaltic intrusion from the mantle produced voluminous silicic magmas through interaction with the crust. We suggest that this tensional regime and the resulting enhanced magmatism were produced by translation of right-lateral strike-slip on the Walker Lane into ENE transtension in the Lassen region. We further note that changes in tectonic activity along parts of the Walker Lane at ~3.5 Ma appear to correlate with the inception of volcanism along the Cascade Volcanic Arc in the Lassen region. We speculate that, beginning at 3.5 Ma, the northern Walker Lane increasingly interacted with the Cascade subduction zone to produce transtensional environments favorable to the development of major volcanic centers.

  12. Limitations of child injury data from the CPSC's National Electronic Injury Surveillance System: the case of baby walker related data.

    PubMed Central

    Weiss, H. B.

    1996-01-01

    OBJECTIVES: The US Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS) is a primary source for children's consumer product injury surveillance data in the US. Differing interpretations of the emergency department based NEISS baby walker data by various parties prompted this detailed examination, reclassification, and analysis of the NEISS data to explain these discrepancies. METHODS: Case selection was performed by searching the NEISS 1982-91 database for the baby walker product code and various text strings for children less than 24 months old. False negative and false positive cases were identified and reclassified. Adjusted population rates were computed and the types and locations of hospitals contributing to the sample were examined. RESULTS: One per cent false positive and 4% false negative misclassification rates were observed. In 1991, two children's hospitals reported 14% of the baby walker related injuries, though these hospitals made up just 2% of the sample frame. Through random allocation, one state currently contains four acute care hospitals and the only two children's hospitals reporting to the NEISS system. These six hospitals contributed 18% of the walker cases whereas the state represents only 3% of the US infant population. CONCLUSIONS: Misclassification in NEISS baby walker reports is minimal, with false negatives outweighing false positives. For trend analysis of product related injuries at the frequency of occurrence observed for baby walkers, NEISS suffers from low sensitivity due to sampling error. For children's injuries, NEISS' estimates have been affected by children's hospitals coming in and out of the sample and currently reflects a random geographic imbalance because one state contributes both of the reporting children's hospitals. To overcome these problems improved multiple product coding, a unique baby walker code, and stratification of children's hospitals in an enlarged NEISS sample is recommended. PMID:9346058

  13. 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 ?(m). While still alive, the creeper has a finite mean frequency ? 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 ?(m)-dependent optimal frequency ?=?(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

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

    NASA Astrophysics Data System (ADS)

    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 ?m. While still alive, the creeper has a finite mean frequency ? 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 ?m-dependent optimal frequency ? =?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.

  15. 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)

  16. On the scalar particle creation by electromagnetic fields in Robertson-Walker spacetime

    NASA Astrophysics Data System (ADS)

    Sogut, Kenan; Havare, Ali

    2015-12-01

    In the present paper, we obtained the scalar particle creation number density by using the Klein-Gordon equation coupled to the electromagnetic fields in the Robertson-Walker spacetime with the help of the Bogoliubov transformation method. We analyzed the resulting expression for the effect of a time-dependent electric field and a constant magnetic field on the particle production rate and found that the strong time-dependent electric field amplifies the particle creation and the magnetic field reduces the rate, in accordance with the previous findings.

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

    PubMed

    Yang, Chun; Zhi, Xiaoyan; Xu, Hui

    2015-05-15

    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%. PMID:25872985

  18. 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.

  19. 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°; ?95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously unrecognized reference site rotations, and provided an additional reference direction for determining vertical-axis rotation magnitudes. We present a kinematic model based on mean rotation magnitudes of ~30° CW for the Sweetwater Mountains and Bodie Hills that accounts for rotational-strain accommodation of dextral shear in the WCWL since the late Miocene. This model considers rotational magnitudes, paleostrain indicators, edge-effects, and strain-accommodating structures of rotating crustal blocks to represent changes in regional strain accommodation over time. The results and models presented here elucidate the complicated and evolving nature of the WCWL, and further understanding of variations in strain accommodation for the Walker Lane.

  20. Computation of partially invariant solutions for the Einstein Walker manifolds' identifying equations

    NASA Astrophysics Data System (ADS)

    Nadjafikhah, Mehdi; Jafari, Mehdi

    2013-12-01

    In this paper, partially invariant solutions (PISs) method is applied in order to obtain new four-dimensional Einstein Walker manifolds. This method is based on subgroup classification for the symmetry group of partial differential equations (PDEs) and can be regarded as the generalization of the similarity reduction method. For this purpose, those cases of PISs which have the defect structure ?=1 and are resulted from two-dimensional subalgebras are considered in the present paper. Also it is shown that the obtained PISs are distinct from the invariant solutions that obtained by similarity reduction method.

  1. A hydrochemical reconnaissance study of the Walker River basin, California and Nevada

    USGS Publications Warehouse

    Benson, L.V.; Spencer, R.J.

    1983-01-01

    During 1975 and 1976, a large number of water and sediment samples were collected from the Walker River Basin. Additional surface water samples were collected during 1980 and 1981. Data are given herein for chemical analyses of snowmelt, tributary, river, spring, well, lake, reservoir, lake sediment pore fluid, tufa, lake and river sediment samples. These data provide the basis for consideration of processes which govern the chemical evolution of large closed basin hydrologic systems in the Basin and Range Province of the Southwestern United States.

  2. PET/CT in a Patient Diagnosed With Dandy-Walker Syndrome.

    PubMed

    Infante, Jose R; Garcia, Lucia; Rayo, Juan I; Serrano, Justo; Dominguez, Maria L; Moreno, Manuel

    2016-01-01

    The Dandy-Walker syndrome (DWS) is a rare congenital posterior fossa malformation characterized by aplasia or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa. We present a 52-year-old Caucasian man diagnosed with gastrointestinal stromal tumor and submitted to F-FDG PET/CT as a staging procedure. The patient was previously diagnosed with DWS in brain CT scan. PET/CT images revealed an ametabolic large cyst in the posterior fossa and hypoplasia of cerebellar vermis. The case is presented with the aim to show the appearance of this syndrome on PET/CT study. PMID:26053730

  3. Asymptotic behaviour of the relativistic Boltzmann equation in the Robertson-Walker spacetime

    E-print Network

    Ho Lee

    2013-07-22

    In this paper, we study the relativistic Boltzmann equation in the spatially flat Robertson-Walker spacetime. For a certain class of scattering kernels, global existence of classical solutions is proved. We use the standard method of Illner and Shinbrot for the global existence and apply the splitting technique of Guo and Strain for the regularity of solutions. The main interest of this paper is to study the evolution of matter distribution, rather than the evolution of spacetime. We obtain the asymptotic behaviour of solutions and will understand how the expansion of the universe affects the evolution of matter distribution.

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

    E-print Network

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

    2015-12-09

    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.

  5. 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.

  6. 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 ?M 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)].

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

    E-print Network

    Rambeau, Joachim

    2011-01-01

    We study the extreme statistics of N non-intersecting 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 \\tau_M at which this maximum is reached. We focus in particular on non-intersecting Brownian bridges ("watermelons without wall") and non-intersecting Brownian excursions ("watermelons with a wall"). We discuss in detail the relationships between such vicious walkers models in watermelons 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. Le...

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

    E-print Network

    Joachim Rambeau; Gregory Schehr

    2011-02-08

    We study the extreme statistics of N non-intersecting 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 \\tau_M at which this maximum is reached. We focus in particular on non-intersecting Brownian bridges ("watermelons without wall") and non-intersecting Brownian excursions ("watermelons with a wall"). We discuss in detail the relationships between such vicious walkers models in watermelons 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. 91, 60006 (2010)].

  9. A tropical - extratropical cloud albedo control on the warm pool, cold tongue, Walker circulation complex

    NASA Astrophysics Data System (ADS)

    Burls, Natalie; Fedorov, Alexey

    2015-04-01

    What determines the strength of the warm pool, cold tongue, and Walker circulation (WCWC) within the fully coupled ocean-atmosphere system is a central question in tropical climate dynamics. Using a comprehensive coupled model (CESM) we demonstrate how the reflectivity of extratropical, as well as tropical, clouds plays a central role in setting the WCWC strength. In particular, we show that the gradient in cloud albedo between the tropics and mid-latitudes (??) sets the mean east-west SST gradient in the equatorial Pacific. Our experiments reveal a near linear dependence between ?? and the warm pool to cold tongue temperature gradient, which is also seen to hold across the CMIP5 preindustrial control simulations. This relationship is critically dependent on the existence of the oceanic bridge (the oceanic Subtropical Cells), as well as atmospheric coupling between the tropics and mid-latitudes. We explain the close relation between the two variables using an energy balance model incorporating the essential dynamics of the warm pool, cold tongue Walker circulation complex and the influence of the extratropics.

  10. Grain-size data from four cores from Walker Lake, Nevada

    SciTech Connect

    Yount, J.C.; Quimby, M.F.

    1990-11-01

    A number of cores, taken from within and near Walker Lake, Nevada are being studied by various investigators in order to evaluate the late-Pleistocene paleoclimate of the west-central Great Basin. In particular, the cores provide records that can be interpreted in terms of past climate and compared to proposed numerical models of the region`s climate. All of these studies are being carried out as part of an evaluation of the regional paleoclimatic setting of a proposed high-level nuclear waste storage facility at Yucca Mountain, Nevada. Changes in past climate often manifest themselves in changes in sedimentary processes or in changes in the volume of sediment transported by those processes. One fundamental sediment property that can be related to depositional processes is grain size. Grain size effects other physical properties of sediment such as porosity and permeability which, in turn, affect the movement and chemistry of fluids. The purposes of this report are: (1) to document procedures of sample preparation and analysis, and (2) to summarize grain-size statistics for 659 samples from Walker Lake cores 84-4, 84-5, 84-8 and 85-2. Plots of mean particle diameter, percent sand, and the ratio of silt to clay are illustrated for various depth intervals within each core. Summary plots of mean grain size, sorting, and skewness parameters allow comparison of textural data between each core. 15 refs., 8 figs., 3 tabs.

  11. Insights into distributed plate rates across the Walker Lane from GPS geodesy

    NASA Astrophysics Data System (ADS)

    Lifton, Zachery M.; Newman, Andrew V.; Frankel, Kurt L.; Johnson, Christopher W.; Dixon, Timothy H.

    2013-09-01

    geodetic slip rates are observed to be approximately two times greater than late Pleistocene geologic slip rates across the southern Walker Lane. Using a dense GPS network, we compare the present-day crustal velocities to observed geologic slip rates in the region. We find that the Walker Lane is characterized by a smooth transition from westward extension in the Basin and Range to northwestward motion of the Sierra Nevada block. The GPS velocity field indicates that (1) plate parallel (N37°W) velocities define a velocity differential of 10.6 ± 0.5 mm/yr between the western Basin and Range and the Sierra Nevada block, (2) there is ~2 mm/yr of contemporary extension perpendicular to the normal faults of the Silver Peak-Lone Mountain extensional complex, and (3) most of the observed discrepancy in long- and short-term slip rates occurs across Owens Valley. We believe the discrepancy is due to distributed strain and underestimated geologic slip rates.

  12. 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.

  13. Mutations in extracellular matrix genes NID1 and LAMC1 cause autosomal dominant Dandy-Walker malformation and occipital cephaloceles

    PubMed Central

    Darbro, Benjamin W.; Mahajan, Vinit B.; Gakhar, Lokesh; Skeie, Jessica M.; Campbell, Elizabeth; Wu, Shu; Bing, Xinyu; Millen, Kathleen J.; Dobyns, William B.; Kessler, John A.; Jalali, Ali; Cremer, James; Segre, Alberto; Manak, J. Robert; Aldinger, Kimerbly A.; Suzuki, Satoshi; Natsume, Nagato; Ono, Maya; Hai, Huynh Dai; Viet, Le Thi; Loddo, Sara; Valente, Enza M.; Bernardini, Laura; Ghonge, Nitin; Ferguson, Polly J.; Bassuk, Alexander G.

    2013-01-01

    We performed whole-exome sequencing of a family with autosomal dominant Dandy-Walker malformation and occipital cephaloceles (ADDWOC) and detected a mutation in the extracellular matrix protein encoding gene NID1. In a second family, protein interaction network analysis identified a mutation in LAMC1, which encodes a NID1 binding partner. Structural modeling the NID1-LAMC1 complex demonstrated that each mutation disrupts the interaction. These findings implicate the extracellular matrix in the pathogenesis of Dandy-Walker spectrum disorders. PMID:23674478

  14. 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.

  15. in compartment/phosphorylation space Statistics of cellular signal transduction as a race to the nucleus by multiple random walkers

    E-print Network

    Hasty, Jeff

    in compartment/phosphorylation space Statistics of cellular signal transduction as a race.pnas.org/misc/reprints.shtml To order reprints, see: Notes: #12;Statistics of cellular signal transduction as a race to the nucleus by multiple random walkers in compartment phosphorylation space Ting Lu* , Tongye Shen , Chenghang Zong , Jeff

  16. Wafer-level Spatial and Flush Delay Analysis for IDDQ Estimation Sagar S. Sabade Duncan M. Walker

    E-print Network

    Walker, Duncan M. "Hank"

    Wafer-level Spatial and Flush Delay Analysis for IDDQ Estimation Sagar S. Sabade Duncan M. Walker between IDDQ and a second parameter like speed [16], temperature [17], and die position on a wafer [18 median IDDQ for all chips that passed all tests or failed only IDDQ test at the wafer level and had

  17. Course Outline PSYC2700A-Spring 2003, Instructor: S.E. Walker Page 1 of 3 University of Lethbridge

    E-print Network

    Walker, Sean E.

    Instructor: Sean E. Walker Office: C450 (Cricket Lab) Meeting Time: TR 13:40-14:55 Office Hours: M 13 will examine the evolutionary processes responsible for shaping functionally organized behaviors so as to solve documentation verifying the circumstances. Medical reasons must be supported by a statement that test

  18. Scale-Free Distribution of Avian Influenza Outbreaks Michael Small,* David M. Walker, and Chi Kong Tse

    E-print Network

    Tse, Chi K. "Michael"

    Scale-Free Distribution of Avian Influenza Outbreaks Michael Small,* David M. Walker, and Chi Kong for the spread of avian influenza among domestic and wild birds. The network structure we obtain is complex- ine the global spatiotemporal distribution of avian influenza cases in both wild and domestic birds

  19. Learning Scripts as Hidden Markov Models J. Walker Orr, Prasad Tadepalli, Janardhan Rao Doppa, Xiaoli Fern, Thomas G. Dietterich

    E-print Network

    , e.g., "John went to Starbucks. He came back after ten minutes." The standard inference algo- rithmsLearning Scripts as Hidden Markov Models J. Walker Orr, Prasad Tadepalli, Janardhan Rao Doppa sentences, for example, "What did John do in Starbucks?" There are two complications that need to be dealt

  20. rf power system for thrust measurements of a helicon plasma source Alexander W. Kieckhafer and Mitchell L. R. Walker

    E-print Network

    Walker, Mitchell

    geometry.10­14 Helicon plasma sources present very unique engineering challenges. Foremostrf power system for thrust measurements of a helicon plasma source Alexander W. Kieckhafer and Mitchell L. R. Walker Department of Aerospace Engineering, High-Power Electric Propulsion Laboratory

  1. 370 P. L. WALKER,JR.,AND EMILERAATS Vol. 60 EFFECT OF GAS DIFFUSION IN GRAPHITIZED CARBON RODS ON THEIR

    E-print Network

    with carbon dioxide. Introduction Workerss-? have shown that the physical struc- ture of porous catalysts can the diffusion coefficient of hydrogen-nitrogenthrough the porous carbon rods, Daff(Bn-N2),have been described370 P. L. WALKER,JR.,AND EMILERAATS Vol. 60 EFFECT OF GAS DIFFUSION IN GRAPHITIZED CARBON RODS

  2. Binocular Cross-Orientation Suppression in the Cat's Striate Cortex Gary A. Walker, Izumi Ohzawa, Ralph D. Freeman

    E-print Network

    Freeman, Ralph D.

    J0573-7R Binocular Cross-Orientation Suppression in the Cat's Striate Cortex Gary A. Walker, Izumi@pinoko.berkeley.edu Running Title: Binocular cross-orientation suppression Keywords: Visual cortex, binocular vision, binocular disparity, cross-orientation inhibition, gain normalization, interocular masking, dichoptic

  3. 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...

  4. 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…

  5. 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

    ... safety zone around the FPSO significantly reduces the threat of allisions, oil spills, and releases of... center point. The safety zone will reduce significantly the threat of allisions, oil spills, and releases... PIONEER at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico in the Federal Register (74...

  6. Database Research Opportunities in Computer Games Walker White, Christoph Koch, Nitin Gupta, Johannes Gehrke, and Alan Demers

    E-print Network

    . The Entertainment Software Association estimates that computer and video game software sales in 2006 were $7 graphics, there has been little academic impact on the development of computer games. Even in the areaDatabase Research Opportunities in Computer Games Walker White, Christoph Koch, Nitin Gupta

  7. 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).…

  8. Promoting Walker-Assisted Step Responses by an Adolescent with Multiple Disabilities Through Automatically Delivered Stimulation. Research Report

    ERIC Educational Resources Information Center

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Campodonico, Francesca; Oliva, Doretta; Doretta, Cecilia M.

    2005-01-01

    Persons with multiple disabilities often have limited functioning of their lower limbs and tend to spend large amounts of time sitting in a wheelchair. Efforts to enable some of these persons (that is, those who are in better overall physical condition) to make some use of their legs may involve the use of support walkers. The risk may be even…

  9. "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…

  10. 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

  11. 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.

  12. Recent Advances in Profile Soil Moisture Retrieval Jeffrey P. Walker, Garry R. Willgoose and Jetse D. Kalma

    E-print Network

    Walker, Jeff

    Recent Advances in Profile Soil Moisture Retrieval Jeffrey P. Walker, Garry R. Willgoose and Jetse a capability to make frequent and spatially distributed measurements of surface soil moisture, whilst recent of profile soil moisture on a routine basis will require a combination of calibration and evaluation

  13. Forward Kinematic Model for Continuum Robotic Surfaces Jessica Merino Anthony L. Threatt, Ian D. Walker, and Keith E. Green

    E-print Network

    . Walker, and Keith E. Green Abstract-- In this paper, we consider the modeling of robotic continuous. INTRODUCTION The traditional approach to providing movement in both robotics and architecture focuses on the movement of rigid structures (e.g. manipulator links, wheels, doors, and win- dows) along or about surfaces

  14. Neurocutaneous Melanosis in Association with Dandy-Walker Complex with Extensive Intracerebral and Spinal Cord Involvement

    PubMed Central

    Sung, Kyoung-Su

    2014-01-01

    Neurocutaneous melanosis (NCM) is a rare congenital syndrome consisting of benign or malignant melanotic tumors of the central nervous system with large or numerous cutaneous melanocytic nevi. The Dandy-Walker complex (DWC) is characterized by an enlarged posterior fossa with high insertion of the tentorium, hypoplasia or aplasia of the cerebellar vermis, and cystic dilatation of the fourth ventricle. These each two conditions are rare, but NCM associated with DWC is even more rare. Most patients of NCM with DWC present neurological symptoms early in life such as intracranial hemorrhage, hydrocephalus, and malignant transformation of the melanocytes. We report a 14-year-old male patient who was finally diagnosed as NCM in association with DWC with extensive intracerebral and spinal cord involvement. PMID:25289129

  15. 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.

  16. Complete mitochondrial genome of the oriental armyworm Mythimna separata (Walker) (Lepidoptera: Noctuidae).

    PubMed

    Li, Feng-Bo; Wang, Wei; Zhang, Hui-Xian; Shen, Wei-Feng; Xu, Xiao-Yan; Chen, Jin-E; Meng, Zhi-Qi

    2015-12-01

    We determined the complete mitochondrial genome of the oriental armyworm Mythimna separata (Walker) (Lepidoptera: Noctuidae), which is one of the serious cereal pests in Asia and Australia. The circular genome of 15,332?bp in length contains 37 typical animal mitochondrial genes and a non-coding A?+?T-rich region. Its gene content and order are typical of lepidopteran mitochondrial genomes described to date. All protein-coding genes (PCGs) start with an ATN codon except for cox1 and nad1, which use CGA and TTG as their start codon, respectively. Ten PCGs use complete stop codon TAA, whereas three PCGs end with single T. The A?+?T-region is located between rrnS and trnM with a length of 374?bp. The mitochondrial genome sequence benefits future studies of molecular phylogenetics and pest control. PMID:24409861

  17. The complete mitochondrial genome of Myrmeleon immanis Walker, 1853 (Neuroptera: Myrmeleontidae).

    PubMed

    Zhang, Jie; Wang, Xinli

    2016-03-01

    In this study, the complete mitochondrial genome sequence of Myrmeleon immanis Walker, 1853 (Neuroptera: Myrmeleontidae) has been obtained with PCR, which is a circular molecule of 15,802?bp in length, contains 37 typical mitochondrial genes: 13 protein-coding genes (PCGs), 2 ribosomal RNAs, 22 transfer RNAs and a non-coding AT-rich region. The nucleotide composition is biased toward A and T as in most other insects. The A?+?T content of the whole genome, PCGs, tRNAs, rRNAs and the control region is 75.6%, 74.3%, 73.6%, 76.2%, 79.6%. All PCGs start with a typical ATN codon except for the COI which uses ACG as its start codon; all PCGs terminate in the common stop codon TAA or TAG, except for the COI, COII which use single T as their stop codons. PMID:25208184

  18. Hybrid paraplegic locomotion with the ParaWalker using intramuscular stimulation: a single subject study.

    PubMed

    Nene, A V; Jennings, S J

    1989-04-01

    Functional intramuscular electrical stimulation of the gluteus maximus and gluteus medius on the stance side whilst walking is reported. The subject was an adult, male, post-traumatic complete paraplegic with lesion level at T7. He had been using surface stimulation to aid his walking with the adult ParaWalker Orthosis but suffered unpleasant anterior abdominal wall muscle contractions with high amplitude stimulation. The experimental use of percutaneous intramuscular Platinum/Iridium wire electrodes demonstrated that more forceful contractions of the buttock muscles could be achieved without any effect on abdominal wall musculature. This prompted the use of a permanent, implanted system. The system is inductively coupled to an external control device and is working satisfactorily 7 months after implantation. PMID:2785668

  19. Emergence of Space and Spacetime Dynamics of Friedmann-Robertson-Walker Universe

    E-print Network

    Rong-Gen Cai

    2012-07-03

    In a recent paper [arXiv:1206.4916] by T. Padmanabhan, it was argued that our universe provides an ideal setup to stress the issue that cosmic space is emergent as cosmic time progresses and that the expansion of the universe is due to the difference between the number of degrees of freedom on a holographic surface and the one in the emerged bulk. In this note following this proposal we obtain the Friedmann equation of a higher dimensional Friedmann-Robertson-Walker universe. By properly modifying the volume increase and the number of degrees of freedom on the holographic surface from the entropy formulas of black hole in the Gauss-Bonnet gravity and more general Lovelock gravity, we also get corresponding dynamical equations of the universe in those gravity theories.

  20. Dandy-Walker malformation, genitourinary abnormalities, and intellectual disability in two families.

    PubMed

    Zaki, Maha S; Masri, Amira; Gregor, Anne; Gleeson, Joseph G; Rosti, Rasim Ozgur

    2015-11-01

    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. © 2015 Wiley Periodicals, Inc. PMID:26109232

  1. Non-intersecting Brownian walkers and Yang-Mills theory on the sphere

    E-print Network

    Forrester, Peter J; Schehr, Gregory

    2010-01-01

    A scaling regime about the mean of the maximal height of N non-intersecting Brownian excursions ("watermelons" with a wall) is identified, for which the distribution function is identical to that of the scaled largest eigenvalue of GOE random matrices. Large deviation formulas for the maximum height are also computed. Our study relies on a direct correspondence between the distribution function, and the partition function for Yang-Mills theory on a sphere with the gauge group Sp(2N). We also show how known results for the asymptotic analysis of the partition function for Yang-Mills theory on the sphere with gauge group U(N) can be used to study return probabilities for non-intersecting Brownian walkers on a circle.

  2. Walker-Warburg syndrome diagnosed by findings of typical ocular abnormalities on prenatal ultrasound.

    PubMed

    Brasseur-Daudruy, M; Vivier, P H; Ickowicz, V; Eurin, D; Verspyck, E

    2012-04-01

    Walker-Warburg syndrome (WWS) is a rare, lethal autosomal recessive disorder characterized by congenital muscular dystrophy and brain and eye anomalies. A prenatal finding of hydrocephalus associated with posterior fossa anomalies and/or encephalocele is nonspecific, whereas additional ocular anomalies are typical for WWS. We report a fetus of consanguineous parents found to have encephalocele at US in week 15 of gestation. The parents did not wish to terminate the pregnancy. Follow-up US revealed bilateral abnormal ocular echoic structures suggesting a major form of persistent primary vitreous. WWS was suspected. The POMT2 mutation confirmed this diagnosis. In hydrocephalus associated with posterior fossa anomalies and/or encephalocele, we recommend detailed US examination of the fetal eyes. Ocular anomalies in this context strongly suggest WWS. PMID:22002842

  3. 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).

  4. Morphological manifestations of the Dandy-Walker syndrom in female members of a family.

    PubMed

    Titli?, Marina; Alfirevi?, Stanko; Koli?, Krešimir; Soldo, Anamarija; Tripalol, Ana Batoš

    2015-03-01

    The Dandy-Walker syndrome (DWS) is a hereditary disorder, appearing somewhat more frequently in women. The most important characteristics of the DWS are the lack of the cerebellar vermis, varying from a partial lack to a complete agenesis, and enlargement of the cerebrospinal spaces, especially in the fourth ventricle. The above mentioned morphological changes clinically manifest in ataxia, increased intracranial pressure and hydrocephalus. Here is presented a family with DWS, where the disease is contracted only by female members, in two generations, whereas no signs of DWS have been noticed in male family members. DWS is clinically manifested from early childhood to middle age, with the morphological changes varying from hypoplastic cerebellar vermis to widening of the brain ventricles and hydrocephalus and arachnoid cyst in the occipital part. PMID:26040095

  5. Large scale dynamics of the Persistent Turning Walker model of fish behavior

    E-print Network

    Pierre Degond; Sébastien Motsch

    2007-10-26

    This paper considers a new model of individual displacement, based on fish motion, the so-called Persistent Turning Walker (PTW) model, which involves an Ornstein-Uhlenbeck process on the curvature of the particle trajectory. The goal is to show that its large time and space scale dynamics is of diffusive type, and to provide an analytic expression of the diffusion coefficient. Two methods are investigated. In the first one, we compute the large time asymptotics of the variance of the individual stochastic trajectories. The second method is based on a diffusion approximation of the kinetic formulation of these stochastic trajectories. The kinetic model is a Fokker-Planck type equation posed in an extended phase-space involving the curvature among the kinetic variables. We show that both methods lead to the same value of the diffusion constant. We present some numerical simulations to illustrate the theoretical results.

  6. An Extension of Friedmann-Robertson-Walker Theory beyond Big Bang

    E-print Network

    Joachim Schroeter

    2009-07-03

    Starting from the classic Friedmann-Robertson-Walker theory with big bang it is shown that the solutions of the field equations can be extended to negative times. Choosing a new cosmic time scale instead of proper time one achieves complete differentiability of the scale factor and of suitable thermodynamic quantities equivalent to pressure and energy density. Then, the singularity of big bang manifests itself only by the vanishing of the scale factor at time zero. Moreover, all solutions of the field equations are defined for all times from -infinity to +infinity. In a separate chapter the horizon structure of the extended theory is studied. Some weak assumptions guarantee that there are no horizons. Hence, the horizon problem in a strict sence disappears. An intensive discussion of the results is given at the end of the paper.

  7. 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.

  8. Interannual Variability in the Large-Scale Dynamics of the South Asian Summer Monsoon JENNIFER M. WALKER, SIMONA BORDONI, AND TAPIO SCHNEIDER*

    E-print Network

    Heaton, Thomas H.

    . WALKER, SIMONA BORDONI, AND TAPIO SCHNEIDER* California Institute of Technology, Pasadena, California (Gadgil 2003). This year-to-year variability of the SASM is sufficient to trigger drought and flood, California Institute of Technology, 1200 E. Cal

  9. Walker, J. S., Carruthers, A. E., Orr-Ewing, A. J., & Reid, J. P. (2013). Measurements of Light Extinction by Single Aerosol Particles. The Journal

    E-print Network

    Subramanian, Sriram

    2013-01-01

    Walker, J. S., Carruthers, A. E., Orr-Ewing, A. J., & Reid, J. P. (2013). Measurements of Light. Carruthers, Andrew J. Orr-Ewing* and Jonathan P. Reid* School of Chemistry, University of Bristol, Bristol

  10. 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 the meantime, from 1950 to 1956, the NACA had used a P2B-1S (a Navy version of the B-29) to launch the rocket-powered versions of the D-558-2 research aircraft.

  11. 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-end-member mixing model (e.g., increased importance of the two soil end members with increasing flow, and the differences between the stream reaches and among some of the springs) were consistent with a wide variety of environmental observations, including temperature and flow variations at springs, water table responses, the general lack of saturated zones on hillslopes and even near the stream in some places, and the importance of water movement through bedrock.

  12. 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.

  13. 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.

  14. 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

  15. Walker devices and microswitch technology to enhance assisted indoor ambulation by persons with multiple disabilities: three single-case studies.

    PubMed

    Lancioni, Giulio E; Singh, Nirbhay N; O'Reilly, Mark F; Sigafoos, Jeff; Oliva, Doretta; Campodonico, Francesca; Buono, Serafino

    2013-07-01

    These three single-case studies assessed the use of walker devices and microswitch technology for promoting ambulation behavior among persons with multiple disabilities. The walker devices were equipped with support and weight lifting features. The microswitch technology ensured that brief stimulation followed the participants' ambulation responses. The participants were two children (i.e., Study I and Study II) and one man (i.e., Study III) with poor ambulation performance. The ambulation efforts of the child in Study I involved regular steps, while those of the child in Study II involved pushing responses (i.e., he pushed himself forward with both feet while sitting on the walker's saddle). The man involved in Study III combined his poor ambulation performance with problem behavior, such as shouting or slapping his face. The results were positive for all three participants. The first two participants had a large increase in the number of steps/pushes performed during the ambulation events provided and in the percentages of those events that they completed independently. The third participant improved his ambulation performance as well as his general behavior (i.e., had a decline in problem behavior and an increase in indices of happiness). The wide-ranging implications of the results are discussed. PMID:23643772

  16. Hybridization between multi-objective genetic algorithm and support vector machine for feature selection in walker-assisted gait.

    PubMed

    Martins, Maria; Costa, Lino; Frizera, Anselmo; Ceres, Ramón; Santos, Cristina

    2014-03-01

    Walker devices are often prescribed incorrectly to patients, leading to the increase of dissatisfaction and occurrence of several problems, such as, discomfort and pain. Thus, it is necessary to objectively evaluate the effects that assisted gait can have on the gait patterns of walker users, comparatively to a non-assisted gait. A gait analysis, focusing on spatiotemporal and kinematics parameters, will be issued for this purpose. However, gait analysis yields redundant information that often is difficult to interpret. This study addresses the problem of selecting the most relevant gait features required to differentiate between assisted and non-assisted gait. For that purpose, it is presented an efficient approach that combines evolutionary techniques, based on genetic algorithms, and support vector machine algorithms, to discriminate differences between assisted and non-assisted gait with a walker with forearm supports. For comparison purposes, other classification algorithms are verified. Results with healthy subjects show that the main differences are characterized by balance and joints excursion in the sagittal plane. These results, confirmed by clinical evidence, allow concluding that this technique is an efficient feature selection approach. PMID:24444751

  17. Preserving Information from the Beginning to the End of time in a Robertson-Walker Spacetime

    E-print Network

    Stefano Mancini; Roberto Pierini; Mark M. Wilde

    2014-12-23

    Preserving information stored in a physical system subjected to noise can be modeled in a communication-theoretic paradigm, in which storage and retrieval correspond to an input encoding and output decoding, respectively. The encoding and decoding are then constructed in such a way as to protect against the action of a given noisy quantum channel. This paper considers the situation in which the noise is not due to technological imperfections, but rather to the physical laws governing the evolution of the universe. In particular, we consider the dynamics of quantum systems under a 1+1 Robertson-Walker spacetime and find that the noise imparted to them is equivalent to the well known amplitude damping channel. Since one might be interested in preserving both classical and quantum information in such a scenario, we study trade-off coding strategies and determine a region of achievable rates for the preservation of both kinds of information. For applications beyond the physical setting studied here, we also determine a trade-off between achievable rates of classical and quantum information preservation when entanglement assistance is available.

  18. 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

  19. Electrodynamics in Friedmann-Robertson-Walker Universe: Maxwell and Dirac fields in Newman-Penrose formalism

    E-print Network

    U. Khanal

    2006-06-23

    Maxwell and Dirac fields in Friedmann-Robertson-Walker spacetime is investigated using the Newman-Penrose method. The variables are all separable, with the angular dependence given by the spin-weighted spherical harmonics. All the radial parts reduce to the barrier penetration problem, with mostly repulsive potentials representing the centrifugal energies. Both the helicity states of the photon field see the same potential, but that of the Dirac field see different ones; one component even sees attractive potential in the open universe. The massless fields have the usual exponential time dependencies; that of the massive Dirac field is coupled to the evolution of the cosmic scale factor $a$. The case of the radiation filled flat universe is solved in terms of the Whittaker function. A formal series solution, valid in any FRW universe, is also presented. The energy density of the Maxwell field is explicitly shown to scale as $a^{-4}$. The co-moving particle number density of the massless Dirac field is found to be conserved, but that of the massive one is not. Particles flow out of certain regions, and into others, creating regions that are depleted of certain linear and angular momenta states, and others with excess. Such current of charged particles would constitute an electric current that could generate a cosmic magnetic field. In contrast, the energy density of these massive particles still scales as $a^{-4}$.

  20. Stress-Energy Tensor of the Quantized Massive Fields in Friedman-Robertson-Walker Spacetimes

    E-print Network

    Jerzy Matyjasek; Pawe? Sadurski

    2013-11-17

    The approximate stress-energy tensor of the quantized massive scalar, spinor and vector fields in the spatially flat Friedman-Robertson-Walker universe is constructed. It is shown that for the scalar fields with arbitrary curvature coupling, $\\xi,$ the stress-energy tensor calculated within the framework of the Schwinger-DeWitt approach is identical to the analogous tensor constructed in the adiabatic vacuum. Similarly, the Schwinger-DeWitt stress-energy tensor for the fields of spin 1/2 and 1 coincides with the analogous result calculated by the Zeldovich-Starobinsky method. The stress-energy tensor thus obtained are subsequently used in the back reaction problem. It is shown that for pure semiclassical Einstein field equations with the vanishing cosmological constant and the source term consisting exclusively of its quantum part there are no self-consistent exponential solutions driven by the spinor and vector fields. A similar situation takes place for the scalar field if the coupling constant belongs to the interval $\\xi \\gtrsim 0.1.$ For a positive cosmological constant the expansion slows down for all considered types of massive fields except for minimally coupled scalar field. The perturbative approach to the problem is briefly discussed and possible generalizations of the stress-energy tensor are indicated.

  1. Morphological descriptions on the larvae of Hypopygiopsis fumipennis (Walker, 1856) (Diptera: Calliphoridae).

    PubMed

    Heo, C C; Latif, B; Silahuddin, S A; Nazni, W A; Omar, B

    2015-03-01

    The study on biodiversity of forensically important Diptera in the tropical rain forest in Malaysia is scarce. Thus, a preliminary survey was conducted at a jungle fringe near Kampung Bahagia Bukit Lagong, Sungai Buloh, Selangor. A rat carcass was offered to attract carrion flies and we collected an adult female calliphorid, Hypopygiopsis fumipennis (Walker, 1856) during the fresh stage of carcass decomposition. The female fly was allowed to oviposit on chicken liver in a container and the resulting larvae were reared to the adult stage. Along the developmental process, several individuals from each instar were collected and preserved in 70% ethanol and then processed on the slides. We recorded the duration of development for each instar and described its larval features for the first time. The third instar larvae of H. fumipennis showed accessory oral sclerite present, anterior spiracle with 13-15 papillae, intersegmental spines mostly unicuspid with pointed end, and posterior spiracles heavily sclerotized with inter-slit projections. Some larval differences between H. fumipennis and Hypopygiopsis violacea were noted. PMID:25801265

  2. 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.

  3. South China Sea hydrological changes and Pacific Walker Circulation variations over the last millennium

    PubMed Central

    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. PMID:21522137

  4. Occurrence and characterization of a tetrahedral nucleopolyhedrovirus from Spilarctia obliqua (Walker).

    PubMed

    Senthil Kumar, C M; Jacob, T K; Devasahayam, S; D'Silva, Sharon; Jinsha, J; Rajna, S

    2015-11-01

    Spilarctia obliqua Walker (Lepidoptera: Arctiidae) is a polyphagous insect pest damaging pulses, oil seeds, cereals, vegetables and medicinal and aromatic plants in India. The pest also infests turmeric and ginger sporadically in Kerala. We observed an epizootic caused by a nucleopolyhedrovirus (NPV) in field populations of the insects in December 2013. The NPV was purified and characterized. The isolate was tetrahedral in shape and belonged to multicapsid NPV. The REN profile of the SpobNPV genome with Pst I, Xho I and HindIII enzymes showed a genome size of 99.1±3.9kbp. Partialpolh, lef-8 and lef-9 gene sequences of the isolate showed a close relationship with HycuNPV and SpphNPV. Phylogram and K-2-P distances between similar isolates suggested inclusion of the present SpobNPV isolate to group I NPV. The biological activity of the isolate was tested under laboratory conditions against third instar larvae of S. obliqua and the LC50 was 4.37×10(3)OBs/ml occlusion bodies (OBs) per ml. The median survival time (ST50) was 181h at a dose of 1×10(6)OBs/ml and 167h at a dose of 1×10(8)OBs/ml. SpobNPV merits further field evaluation as a potential biological control agent of S. obliqua, a serious pest of many agriculturally important crops in the Oriental region. PMID:26449395

  5. Giant congenital melanocytic naevus associated with Dandy-Walker malformation, lipomatosis and hemihypertrophy of the leg.

    PubMed

    Gönül, M; Soylu, S; Gül, U; Aslan, E; Unal, T; Ergül, G

    2009-07-01

    A 30-year-old woman presented with congenital hyperpigmented plaques and multiple tumoral lesions. Her left leg was hypertrophic, although the bones were normal. Dermatological examination revealed hyperpigmented macules and plaques with hair on the legs, abdominal and lumbar areas (covering > 60% of the total body surface) and multiple naevi on the face, arms, back and chest. Multiple soft masses of various sizes, some of which colocalized with hyperpigmented plaques, were seen on the trunk and legs. Malignant melanoma was excluded by histopathological examinations of multiple biopsy specimens obtained from the pigmented lesions. Histopathological examination of one of the soft masses showed that it was a lipoma. Cranial magnetic resonance imaging and computed tomography scans showed an enlarged fourth ventricule and vermis hypoplasia (Dandy-Walker malformation; DWM). Neurocutaneous melanosis is a rare combined abnormality of the skin and central nervous system. A few case reports relating to the coexistence of giant congenital melanocytic naevus, lipomatosis and hemihypertrophy have been published in the literature. We report this very rare case of giant melanocytic naevus with lipomatosis, hemihypertrophy of the leg, and DWM. PMID:19438567

  6. Effect of methotrexate on perfusion and nitrogen-13 glutamate uptake in the Walker-256 carcinosarcoma

    SciTech Connect

    Knapp, W.H.; Panzer, M.; Helus, F.; Layer, K.; Sinn, H.J.; Ostertag, H.

    1988-02-01

    The tissue uptake of (/sup 13/N)glutamate (glu) was related to that of (/sup 11/C)butanol (but), a highly diffusible perfusion tracer. In 25 rats bearing Walker-256 carcinomas tumor-to-muscle glu uptake averaged 6.34 +/- 2.84 (s.d.) prior to interventions and the respective uptake of but was 6.79 +/- 3.08 (y = 0.03 + 0.94x). One hour after selective intraarterial administration of methotrexate (mtx), glu uptake fell by 47%, whereas blood flow remained within the pretreatment range (N = 9). Four hours after mtx, perfusion was reduced by approximately 40%, and 2 days later both perfusion and glu uptake reached extremely low levels. No significant difference in the effect of 10 and 50 mg/kg mtx was observed. Regional tissue mtx uptake estimations using /sup 77/Br-labeled bromomethotrexate did not reveal any significant uptake in muscle. The relationship between tumor-to-muscle uptake of glu and but (/sup 13/N//sup 11/C-index) was 0.94 +/- 0.015 (s.e.m., N = 25) before intervention. After methotrexate (1 hr, 4 hr, and 2 days) this index was 0.58 +/- 0.06 (N = 9), and 0.85 +/- 0.04 (N = 11) and 1.03 +/- 0.05 (N = 5), respectively. These values demonstrate an early mtx-induced uncoupling of glu uptake with respect to perfusion.

  7. 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.

  8. Optical Coherence Tomography in an Infant with Walker-Warburg Syndrome

    PubMed Central

    Mano, Natsuko; Mitsutsuji, Tatsuma; Yoshikawa, Yamato; Miyamoto, Makiko; Watanabe, Hiroko; Shimizu, Kazuhiro; Miki, Michiko; Mimura, Masashi; Ueki, Mari; Ikeda, Tsunehiko

    2015-01-01

    Purpose Walker-Warburg syndrome (WWS) is a type of congenital muscular dystrophy (CMD) characterised by severe brain malformation, lissencephaly, and congenital eye abnormalities. Despite the coexistence of various eye abnormalities, results from optical coherence tomography (OCT) in WWS have not previously been reported. We herein report specific OCT findings in an infant with WWS. Patients and Methods The patient was a 14-day-old boy delivered by caesarean section at 38 weeks and 4 days of gestation and with a birth weight of 2,543 g. A cranial MRI showed lissencephaly, hydrocephalus, an encephalocele, and cerebellar hypoplasia, consistent with the diagnosis of WWS. Results A bilateral ocular examination showed no abnormalities of the anterior eye segment. A fundus examination showed a persistent hyaloid artery in the vitreous cavity, a widespread loss of fundus pigmentation, transparent choroidal vessels (some choroidal vessel sections were visible), and the absence of a distinct macular reflex. OCT showed no foveal pit and an indistinct laminar structure of the retina. The infant subsequently developed congenital glaucoma and he then died of respiratory failure at the age of 8 months. Conclusions WWS is associated with a high incidence of congenital eye abnormalities, and this infant showed findings consistent with WWS. OCT revealed a marked retinal dysplasia. PMID:26265907

  9. [Risk predictive model for damage caused by the spittlebug Aeneolamiapostica (Walker) Fennah (Hemiptera: Cercopidae)].

    PubMed

    García-García, Carlos G; López-Collado, José; Nava-Tablada, Martha E; Villanueva-Jiménez, Juan A; Vera-Graziano, Jorge

    2006-01-01

    This paper evaluated the risk that Aenolamia postica (Walker) Fennah populations reach the economic threshold in sugar cane fields in Veracruz, México. A risk deductive model was constructed to include the sequence of events leading to damaging populations, considered the top event or critical failure in the crop. Model events were identified and quantified, and model was validated on field conditions. The model components and their state values were identified as: temperature e" 28 degrees C, precipitation e" 45% during June and July, soil clay content e" 40%, infested adjoining fields, deficient weed control, wind dominance, crop phenology and variety, deficient chemical and biological control, and irrigation. Sensitivity analysis showed that the most important events triggering high densities of A. postica were high temperatures and precipitation, previous field infestation, nymph and weed presence. Event probability estimates were combined using Boolean algebra to compute the minimum, mean and maximum probabilities for the top event, yielding values of 0.417, 0.563, y 0.734 respectively. Model was tested in field, by selecting sugar cane fields having the model properties and compared to fields without these features. Fields were sampled in both conditions during 2004 year and high-risk fields had significantly (F = 13, 4, gl = 1, 18, P = 0,0018) higher densities (2.4 adults m(-1)) than low-risk plots (0.4 adults m(-1)) thus agreeing with the model forecast. PMID:17144142

  10. Founder Fukutin mutation causes Walker-Warburg syndrome in four Ashkenazi Jewish families†

    PubMed Central

    Chang, Wendy; Winder, Thomas L.; LeDuc, Charles A.; Simpson, Lynn L.; Millar, William S.; Dungan, Jeffrey; Ginsberg, Norman; Plaga, Stacey; Moore, Steven A.; Chung, Wendy K.

    2009-01-01

    Objective Walker-Warburg syndrome (WWS) is a genetically heterogeneous congenital muscular dystrophy caused by abnormal glycosylation of ?-dystroglycan (?-DG) that is associated with brain malformations and eye anomalies. The Fukutin (FKTN) gene, which causes autosomal recessively inherited WWS is most often associated with Fukuyama congenital muscular dystrophy in Japan. We describe the clinical features of four nonconsanguinous Ashkenazi Jewish families with WWS and identify the underlying genetic basis for WWS. Method We screened for mutations in POMGnT1, POMT1, POMT2, and FKTN, genes causing WWS, by dideoxy sequence analysis. Results We identified an identical homozygous c.1167insA mutation in the FKTN gene on a common haplotype in all four families and identified 2/299 (0.7%) carriers for the c.1167insA mutation among normal American Ashkenazi Jewish adults. Conclusion These data suggest that the c.1167insA FKTN mutation described by us is a founder mutation that can be used to target diagnostic testing and carrier screening in the Ashkenazi Jewish population. PMID:19266496

  11. 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. PMID:26385320

  12. Risk factors for Dandy-Walker malformation: a population-based assessment.

    PubMed

    Reeder, Matthew R; Botto, Lorenzo D; Keppler-Noreuil, Kim M; Carey, John C; Byrne, Janice L B; Feldkamp, Marcia L

    2015-09-01

    Dandy-Walker malformation (DWM) is the most common congenital malformation of the cerebellum, but its causes are largely unknown. An increasing number of genes associated with congenital cerebellar malformations have been identified; however, few studies have examined the potential role of non-genetic, potentially modifiable risk factors. From the National Birth Defects Prevention Study, we examined maternal, paternal, and infant characteristics and maternal conditions and periconceptional exposures (from 1 month before to 3 months after conception) among infants with DWM (n?=?160) and unaffected controls (n?=?10,200), delivered between 1997 and 2009. Odds ratios, crude (cOR) and adjusted (aOR) were computed using logistic regression. Maternal factors associated with DWM included non-Hispanic black race/ethnicity (aOR?=?2.0, 95%CI: 1.3-3.2). Among maternal conditions, a history of infertility increased the risk for DWM (all: aOR?=?2.4, 95%CI: 1.3-4.6; multiple: aOR?=?3.9, 95%CI: 1.7-8.9). The lack of association with many maternal exposures supports the hypothesis of a major contribution of genetic factors to the risk for DWM; however, the observed associations with maternal non-Hispanic black race/ethnicity and maternal history of infertility indicate that further research into factors underlying these characteristics may uncover potentially modifiable risk factors, acting alone or as a component of gene-environment interactions. PMID:25941000

  13. New Test of the Friedmann-Lemaître-Robertson-Walker Metric Using the Distance Sum Rule

    NASA Astrophysics Data System (ADS)

    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 z1 and from z1 to z2 to the distance from 0 to z2. 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

  14. Bubble merging in breathing DNA as a vicious walker problem in opposite potentials

    E-print Network

    Jonas Nyvold Pedersen; Mikael Sonne Hansen; Tomas Novotny; Tobias Ambjornsson; Ralf Metzler

    2009-06-04

    We investigate the coalescence of two DNA-bubbles initially located at weak domains and separated by a more stable barrier region in a designed construct of double-stranded DNA. In a continuum Fokker-Planck approach, the characteristic time for bubble coalescence and the corresponding distribution are derived, as well as the distribution of coalescence positions along the barrier. Below the melting temperature, we find a Kramers-type barrier crossing behavior, while at high temperatures, the bubble corners perform drift-diffusion towards coalescence. In the calculations, we map the bubble dynamics on the problem of two vicious walkers in opposite potentials. We also present a discrete master equation approach to the bubble coalescence problem. Numerical evaluation and stochastic simulation of the master equation show excellent agreement with the results from the continuum approach. Given that the coalesced state is thermodynamically stabilized against a state where only one or a few base pairs of the barrier region are re-established, it appears likely that this type of setup could be useful for the quantitative investigation of thermodynamic DNA stability data as well as the rate constants involved in the unzipping and zipping dynamics of DNA, in single molecule fluorescence experiments.

  15. 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 elevated (range 0.263 to 0.863 ?g/g, dry weight). Mercury concentrations in the Walker Lake tui chub, the most abundant and likely prey for common loons, ranged from approximately 0.09 ?g/g to approximately 0.9 ?g/g (wet weight). Larger tui chub in the lake, which are most likely older, had the highest mercury concentrations. Blood samples from 94 common loons collected at Walker Lake between 1998 and 2001 contained a mean mercury concentration of 2.96 ?g/g (standard deviation 1.72 ?g/g). These levels were substantially higher than those found in more than 1,600 common loons tested across North America. Among the 1,600 common loons, the greatest blood mercury concentration, 9.46 ?g/g, was from a loon at Walker Lake. According to risk assessments for northeastern North America, blood mercury concentrations exceeding 3.0 ?g/g cause behavioral, reproductive, and physiological effects. At least 52 percent of the loons at Walker Lake are at risk for adverse effects from mercury on the basis of their blood-mercury concentrations. The larger loons staging in the spring are the most at risk group. The elevated mercury levels found in tui chub and common loons indicate that there is a potential threat to the well being and reproduction of fish and wildlife that use Walker Lake. Wildlife that use Weber Reservoir may also be at risk because it is the first reservoir downstream from mining activities in the Bodie and Aurora areas and mercury concentrations in sediment were elevated. Additional data on mercury concentrations in top level predators, such as piscivorous fish and birds, are needed to assess public health and other environmental risks.

  16. 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 descent and horizontal translations. Sixteen smaller hydrogen-peroxide rockets, mounted in pairs, gave the pilot control in pitch, yaw, and roll. On the LLRV, in case of jet engine failure, six-500-pounds-of thrust rockets could be used by the pilot to carefully apply lift thrust during the rapid descent to hopefully achieve a controllable landing. The pilot's platform extended forward between two legs while an electronics platform, similarly located, extended rearward. The pilot had a zero-zero ejection seat that would then lift him away to safety. Weight and balance design constraints were among the most challenging to meet for all phases of the program (design, development, operations). The two LLRVs were shipped disassembled from Bell to the FRC in April 1964, with program emphasis placed on vehicle No. 1. The scene then shifted to the old South Base area of Edwards Air Force Base. On the day of the first flight, Oct. 30, 1964, NASA research pilot Joe Walker flew it three times for a total of just under 60 seconds, to a peak altitude of approximately 10 feet. By mid-1966 the NASA Flight Research Center had accumulated enough data from the LLRV flight program to give Bell a contract to deliver three Lunar Landing Training Vehicles (LLTVs) at a cost of $2.5 million each. As 1966 ended, the LLRV #1 had flown 198 flights, and the LLRV #2 was being assembled, instrumented and cockpit modifications made at the South Base. The first flight of the number two LLRV in early January 1967 was quickly followed by five more. In December 1966 vehicle No. 1 was shipped to Houston, followed by No. 2 in mid January 1967. When Dryden's LLRVs arrived at Houston they joined the first of the LLTVs to eventually make up the five-vehicle training and simulator fleet. All five vehicles were relied on for simulation and training of moon landings.

  17. Stress-energy tensor of adiabatic vacuum in Friedmann-Robertson-Walker spacetimes

    SciTech Connect

    Kaya, Ali; Tarman, Merve E-mail: merve.tarman@boun.edu.tr

    2011-04-01

    We compute the leading order contribution to the stress-energy tensor corresponding to the modes of a quantum scalar field propagating in a Friedmann-Robertson-Walker universe with arbitrary coupling to the scalar curvature, whose exact mode functions can be expanded as an infinite adiabatic series. While for a massive field this is a good approximation for all modes when the mass of the field m is larger than the Hubble parameter H, for a massless field only the subhorizon modes with comoving wave-numbers larger than some fixed k{sub *} obeying k{sub *}/a > H can be analyzed in this way. As infinities coming from adiabatic zero, second and fourth order expressions are removed by adiabatic regularization, the leading order finite contribution to the stress-energy tensor is given by the adiabatic order six terms, which we determine explicitly. For massive and massless modes these have the magnitudes H{sup 6}/m{sup 2} and H{sup 6}a{sup 2}/k{sub *}{sup 2}, respectively, and higher order corrections are suppressed by additional powers of (H/m){sup 2} and (Ha/k{sub *}){sup 2}. When the scale factor in the conformal time ? is a simple power a(?) = (1/?){sup n}, the stress-energy tensor obeys P = Ø? with Ø = (n?2)/n for massive and Ø = (n?6)/(3n) for massless modes. In that case, the adiabaticity is eventually lost when 0 < n < 1 for massive and when 0 < n < 3/2 for massless fields since in time H/m and Ha/k{sub *} become order one. We discuss the implications of these results for de Sitter and other cosmologically relevant spaces.

  18. Recurrent pseudo-TORCH appearances of the brain presenting as "Dandy-Walker" malformation.

    PubMed

    Cohen, Marta C; Karaman, Ilgin; Squier, Waney; Farrel, Tom; Whitby, Elspeth H

    2012-01-01

    Dandy-Walker malformation (DWM) is a developmental abnormality characterized by cystic dilatation of the fourth ventricle, complete or partial agenesis of the cerebellar vermis, and enlarged posterior fossa with upward displacement of the lateral sinuses, tentorium, and torcula. Calcification of brain tissue is a feature of congenital infection, particularly those involving the TORCH ( Toxoplasma gondii , rubella virus, Cytomegalovirus, and herpesvirus) group. An autosomal-recessive congenital infection-like syndrome with intracranial and extracranial calcifications has been categorized as pseudo-TORCH syndrome. We describe two male siblings diagnosed as DWM by ultrasound and by in utero and postmortem magnetic resonance imaging (MRI) but in whom the neuropathology revealed features of intracranial necrosis and calcification in the absence of extracranial calcific deposition. The fetal anomaly was identified by routine prenatal ultrasound scan at 16 weeks. In both cases the postmortem MRI showed bilateral ventriculomegaly with distortion of the overlying cortices, enlarged posterior fossa with a cyst related to small cerebellar hemispheres, and an incomplete cerebellar vermis. The diagnosis of DWM was offered. The histology revealed hypoplastic cerebral hemispheres with poorly cellular developing cortex. The white matter and periventricular matrix were disrupted by areas of necrosis and calcification not associated with any inflammatory infiltration, organisms, inclusions, or giant cells. To our knowledge, these two male siblings are the 1st cases that show pseudo-TORCH syndrome with distinctive intracranial calcification presenting as DWM. An autosomal-recessive or X-linked inheritance needs to be considered. Our study confirms the relevance of the multidisciplinary teamwork involved in the diagnosis of these complex cases. PMID:21762029

  19. Stress-energy tensor of adiabatic vacuum in Friedmann-Robertson-Walker spacetimes

    NASA Astrophysics Data System (ADS)

    Kaya, Ali; Tarman, Merve

    2011-04-01

    We compute the leading order contribution to the stress-energy tensor corresponding to the modes of a quantum scalar field propagating in a Friedmann-Robertson-Walker universe with arbitrary coupling to the scalar curvature, whose exact mode functions can be expanded as an infinite adiabatic series. While for a massive field this is a good approximation for all modes when the mass of the field m is larger than the Hubble parameter H, for a massless field only the subhorizon modes with comoving wave-numbers larger than some fixed k* obeying k*/a > H can be analyzed in this way. As infinities coming from adiabatic zero, second and fourth order expressions are removed by adiabatic regularization, the leading order finite contribution to the stress-energy tensor is given by the adiabatic order six terms, which we determine explicitly. For massive and massless modes these have the magnitudes H6/m2 and H6a2/k*2, respectively, and higher order corrections are suppressed by additional powers of (H/m)2 and (Ha/k*)2. When the scale factor in the conformal time ? is a simple power a(?) = (1/?)n, the stress-energy tensor obeys P = Ø? with Ø = (n-2)/n for massive and Ø = (n-6)/(3n) for massless modes. In that case, the adiabaticity is eventually lost when 0 < n < 1 for massive and when 0 < n < 3/2 for massless fields since in time H/m and Ha/k* become order one. We discuss the implications of these results for de Sitter and other cosmologically relevant spaces.

  20. Characterization and Comparative Profiling of MicroRNAs in a Sexual Dimorphism Insect, Eupolyphaga sinensis Walker

    PubMed Central

    Li, Chengjun; Wang, Yanyun; Sang, Ming; Zhang, Yi; Li, Bin

    2013-01-01

    Background MicroRNAs are now recognized as key post-transcriptional regulators in animal ontogenesis and phenotypic diversity. Eupolyphaga sinensis Walker (Blattaria) is a sexually dimorphic insect, which is also an important source of material used in traditional Chinese medicine. The male E. sinensis have shorter lifecycles and go through fewer instars than the female. Furthermore, the males have forewings, while the females are totally wingless. Results We used the Illumina/Solexa deep sequencing technology to sequence small RNA libraries prepared from the fourth-instar larvae of male and female E. sinensis. 19,097,799 raw reads were yielded in total: 7,817,445 reads from the female library and 11,280,354 from the male, respectively. As a result, we identified 168 known miRNAs belonging to 55 families as well as 204 novel miRNAs. Moreover, 45 miRNAs showed significantly different expression between the female and the male fourth-instar larvae, and we validated 10 of them by Stem-loop qRT-PCR. Some of these differentially expressed miRNAs are related to metamorphosis, development and phenotypic diversity. Conclusions/Significance This is the first comprehensive description of miRNAs in E. sinensis. The results provide a useful resource for further in-depth study on molecular regulation and evolution of miRNAs. These findings not only enrich miRNAs for hemimetabolans but also lay the foundation for the study of post-transcriptional regulation on the phenomena of sexual dimorphism. PMID:23620723

  1. On a c(t)-Modified Friedman-Lemaitre-Robertson-Walker Universe

    E-print Network

    Robert C. Fletcher

    2013-07-22

    This paper presents a compelling argument for the physical light speed in the homogeneous and isotropic Friedman-Lemaitre-Robertson-Walker (FLRW) universe to vary with the cosmic time coordinate t of FLRW. It will be variable when the radial co-moving differential coordinate of FLRW is interpreted as physical and therefor transformable by a Lorentz transform locally to differentials of stationary physical coordinates. Because the FLRW differential radial distance has a time varying coefficient a(t), in the limit of a zero radial distance the light speed c(t) becomes time varying, proportional to the square root of the derivative of a(t) Since we assume homogeneity of space, this derived c(t) is the physical light speed for all events in the FLRW universe. This impacts the interpretation of astronomical observations of distant phenomena that are sensitive to light speed. A transform from FLRW is shown to have a physical radius out to all radial events in the visible universe. This shows a finite horizon beyond which there are no galaxies and no space. The general relativity (GR) field equation to determine a(t) and c(t) is maintained by using a variable gravitational constant and rest mass that keeps constant the gravitational and particle rest energies. This keeps constant the proportionality constant between the GR tensors of the field equation and conserves the stress-energy tensor of the ideal fluid used in the FLRW GR field equation. In the same way all of special and general relativity can be extended to include a variable light speed.

  2. 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.

  3. 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 findings that tropical ocean evaporation increased by order 5% or more during the 1990s, reconciling this with GPCP precipitation variations.

  4. Prenatal diagnosis of cobblestone lissencephaly associated with Walker-Warburg syndrome based on a specific sonographic pattern.

    PubMed

    Lacalm, A; Nadaud, B; Massoud, M; Putoux, A; Gaucherand, P; Guibaud, L

    2016-01-01

    We report a specific sonographic cerebral pattern of cobblestone lissencephaly (CL) that has not been described previously. This pattern was encountered in four index cases and allowed prenatal diagnosis of CL associated with Walker-Warburg syndrome. The pattern included both an outer echogenic band with reduced pericerebral space, corresponding to an infra- and supratentorial extracortical layer of neuroglial overmigration on pathological examination, and a 'Z'-shaped appearance of the brainstem. This pattern was found as early as 14 weeks' gestation in one of our cases. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd. PMID:26315758

  5. 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 south. Several locations show domains of clockwise vertical-axis rotation up to 50° adjacent to regions of low or no rotation; indicating that simplistic block models of vertical-axis rotation accommodating dextral shear may require re-evaluation. Earthquake focal mechanism inversions have shown that strain near Bridgeport, CA is characterized by nearly pure normal faulting. As dip-slip faulting is not favorable to vertical-axis rotation, this suggests a change in style of strain accommodation since the time of Stanislaus Group emplacement. Ongoing work will refine tectonic domain boundaries within the research area to produce a kinematic model that includes changes in strain accommodation style and rates of vertical-axis rotation.

  6. 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. PMID:25997155

  7. 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.

  8. 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 ??

  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 here is well suited to diseases where there is not a predisposition for contraction within the population. One of the advantages of agent-based modeling is the ability to set up a rare event and develop policy as to how one may mitigate damages arising from it. PMID:19922684

  10. 3-D Ultrasound Segmentation of the Placenta Using the Random Walker Algorithm: Reliability and Agreement.

    PubMed

    Stevenson, Gordon N; Collins, Sally L; Ding, Jane; Impey, Lawrence; Noble, J Alison

    2015-12-01

    Volumetric segmentation of the placenta using 3-D ultrasound is currently performed clinically to investigate correlation between organ volume and fetal outcome or pathology. Previously, interpolative or semi-automatic contour-based methodologies were used to provide volumetric results. We describe the validation of an original random walker (RW)-based algorithm against manual segmentation and an existing semi-automated method, virtual organ computer-aided analysis (VOCAL), using initialization time, inter- and intra-observer variability of volumetric measurements and quantification accuracy (with respect to manual segmentation) as metrics of success. Both semi-automatic methods require initialization. Therefore, the first experiment compared initialization times. Initialization was timed by one observer using 20 subjects. This revealed significant differences (p < 0.001) in time taken to initialize the VOCAL method compared with the RW method. In the second experiment, 10 subjects were used to analyze intra-/inter-observer variability between two observers. Bland-Altman plots were used to analyze variability combined with intra- and inter-observer variability measured by intra-class correlation coefficients, which were reported for all three methods. Intra-class correlation coefficient values for intra-observer variability were higher for the RW method than for VOCAL, and both were similar to manual segmentation. Inter-observer variability was 0.94 (0.88, 0.97), 0.91 (0.81, 0.95) and 0.80 (0.61, 0.90) for manual, RW and VOCAL, respectively. Finally, a third observer with no prior ultrasound experience was introduced and volumetric differences from manual segmentation were reported. Dice similarity coefficients for observers 1, 2 and 3 were respectively 0.84 ± 0.12, 0.94 ± 0.08 and 0.84 ± 0.11, and the mean was 0.87 ± 0.13. The RW algorithm was found to provide results concordant with those for manual segmentation and to outperform VOCAL in aspects of observer reliability. The training of an additional untrained observer was investigated, and results revealed that with the appropriate initialization protocol, results for observers with varying levels of experience were concordant. We found that with appropriate training, the RW method can be used for fast, repeatable 3-D measurement of placental volume. PMID:26341043

  11. Flip-chip electronic system assembly process and issues for the NanoWalker: a small wireless autonomous instrumented robot

    NASA Astrophysics Data System (ADS)

    Martel, Sylvain M.; Riley, George A.; Merchant, Monisha; Hunter, Ian W.; Lafontaine, Serge

    1999-08-01

    The integration of complex electronic systems onto small- scale robots requires advanced assembly methods. The NanoWalker is an example of such a robot where a large amount of electronics must be embedded in the smallest possible space. To make a space-efficient implementation, electronic chips are mounted using flip chip technology on a pre-bumped flexible printed circuit (FPC). A 3D structure is obtained by mounting the FPC vertically in a triangular fashion above a tripod built with three small piezo-actuated legs used for the walking and rotational motions. Advanced computer aided design systems are used for the design and to generate manufacturing files. Unlike other commercial products such as cellular phones, watches, pagers, cameras, and disk drives that use flip chip technology to achieve the smallest form factor, the assembly process of the NanoWalker is directly dependent on other characteristics of the system. Minimization of coupling noises through proper FPC layout and die placement within temperature constraints due to the proximity of sensitive instrument was a critical factor. The effect of vibration caused by the piezo- actuators and the weight of each die were also other important issues to consider to determine the final placement in order to maintain proper sub-atomic motion behavior.

  12. 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

  13. Physical constraints, fundamental limits, and optimal locus of operating points for an inverted pendulum based actuated dynamic walker.

    PubMed

    Patnaik, Lalit; Umanand, Loganathan

    2015-01-01

    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 (v 0) and step angle ([Formula: see text]) 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 v 0-[Formula: see text] plane. A given average forward velocity [Formula: see text] can be achieved by several combinations of v 0 and [Formula: see text]. Only one of these combinations results in the minimum mechanical power consumption and can be considered the optimum operating point for the given [Formula: see text]. 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 [Formula: see text], 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. PMID:26502096

  14. 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.

  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; Martins, Luciano De P; 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. SEND TO: Office of Undergraduate Education, Walker Lab, Room 4010 (Phone 276-2244, Fax 276-8062) Rev. 12/14 page 1 of 2 UNDERGRADUATE RESEARCH PROGRAM (URP) APPLICATION

    E-print Network

    Stewart, Charles V. "Chuck"

    SEND TO: Office of Undergraduate Education, Walker Lab, Room 4010 (Phone 276-2244, Fax 276: Faculty Research Supervisor Male: Female: Date of Birth: Year: First Year Soph. Jr. Sr. Name: Campus of Undergraduate Education, Walker Lab, Room 4010 (Phone 276-2244, Fax 276-8062) Rev. 12/14 page 2 of 2

  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 distribution of pinon juniper within the study area, and aggregated by ecologically pertinent zones of woodlands. Climate is highly variable and difficult to accurately represent at fine spatial scales, so aggregation to pertinent zones such as lower ecotones, upper ecotones, and main distribution of woodlands, allowed for meaningful inferences of how the amount of change among climatic variables over time were related to densification of pinon juniper canopy. The Mann-Kendall test of trend is able to detect trends in time series stacks of spectral vegetation indexes and discern between both large and small magnitude trends. Within the study area, pinon juniper woodlands showed the greatest increases in canopy density at upper ecotones, followed by lower ecotones. The amount of change corresponds to an increase of about 25% in canopy density over the 30 year time period in the upper ecotones, and about 18% increase at lower ecotones. Larger change at the upper ecotone suggests that pinon juniper is responding to climatic change in line with theories of vegetation response to climate. This is best explained by small increases in winter precipitation and larger increases in minimum temperature. These conditions would favor increased canopy by promoting seedling establishment. Weaker correlations with changes in climatic variables at the lower ecotone suggest that other factors, especially historic land use effects, are likely influencing pinon juniper to a greater degree. This follows others findings concerning encroachment, but suggests that the amount of change among climatic variables directly relates to overall rates of establishment and increasing canopy density. Encroachment at the lower bound of pinon juniper distribution is likely a response to artificial reduction of the realized niche.

  19. 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 litter input in litterfall. The ranking of total nutrient content per leaf in spring foliage was N > K > Ca > Mg > P > Na. The autumn foliage ranking was the same as that for autumn leaf litterfall (Ca > N > K > Mg > P > Na), the change being due to differing behavior of the particular nutrients (translocation, biomass dilution and removal by leaching). In the four forest types analyzed, significant differences occurred in the biomass and individual nutrients recycled to the forest floor. The greatest litterfall and amounts of nitrogen input occurred in the pine forest type. Oak-hickory forests had the greatest litter inputs of magnesium and potassium. Calcium return was greatest in the mesophytic hardwood forest. No marked differences in the amounts of sodium and phosphorus return in the forest floor occurred among mesophytic hardwoods and oak-hickory forest types, which were consistently higher than pine and pine-oak-hickory forest values.

  20. 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 area affected by Long Valley extends from north of Mono Lake southward to Owens Lake, and eastward to the Mina deflection of the Walker Lane, potentially influencing the estimated slip rates for a dozen or more major faults.

  1. IEEE TRANSACTIONS ON COMPUTERS, VOL. C-28, NO. 9, SEPTEMBER 1979 [1] C. Black, C.-E. Sundberg, and W. K. S. Walker, "Development of a spaceborne

    E-print Network

    Borgs, Christian

    .-E. Sundberg, and W. K. S. Walker, "Development of a spaceborne memory with a single error and erasure. 2528/75/HP, British Aircraft Corp., Bristol, England. [3] R. W. Lucky, J. Salz, and E. J. Weldon, Jr., Principles of Data Communication. New York: McGraw-Hill, 1968. [4] W. W. Peterson and E. J. Weldon, Jr

  2. Collecting at night at the old porch light: Discovery of the light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), in North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The light brown apple moth (LBAM), Epiphyas postvittana (Walker), is a highly polyphagous species that is an important pest of apple and citrus in many parts of the world, primarily Australia and New Zealand. The potential threat of LBAM to North American agriculture was recognized formally in 1957 ...

  3. ^ DECEMBER. 1990BULL. SOC VECTOR ECOL, 15(2): 144-148 THE BLOOD-FEEDING HABITS OF AEDES SOLLICITANS (WALKER)

    E-print Network

    (WALKER) IN RELATION TO EASTERN EQUINE ENCEPHALITIS VIRUS IN COASTAL AREAS OF NEW JERSEY I. HOST SELECTION. The significance of these findings is discussed in relation to the epidemiology of eastern equine encephalitis). Aedessollicitans is also an extremely efficient vector ofeastern equine encephalitis(EEE) virus (Chamberlainet al

  4. 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...

  5. The 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...

  6. A Phase I Archaeological Survey of a 14.125 Acre Tract: The Arbors of Sam Houston Housing Project in Central Walker County, Texas 

    E-print Network

    Moore, William; Wagner, Janet

    2015-06-09

    A Phase Iarcheological assessment of a 14.125 acre tract in central Walker County,Texas was performed in March 1998 by Brazos Valley Research Associates (BVRA) of Bryan, Texas. This is a federal project regulated by the Housing and Urban Development...

  7. The Delta Q Method of Testing the Air Leakage of Ducts Walker, I.S., Dickerhoff, D.J. and Sherman, M.H.

    E-print Network

    LBNL-49749 The Delta Q Method of Testing the Air Leakage of Ducts Walker, I.S., Dickerhoff, D.J. and Sherman, M.H. Indoor Environment Department Lawrence Berkeley National Laboratory ABSTRACT The DeltaQ test in energy efficiency calculations and for compliance testing of duct systems. The DeltaQ test combines

  8. Host range of Tetramesa romana Walker (Hymenoptera: Eurytomidae), a potential biological control of giant reed, Arundo donax L. in North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The eurytomid wasp, Tetramesa romana Walker, was evaluated as a potential biological control agent of the invasive reed grass, Arundo donax in North America. No-choice tests and timed behavioral studies were used to determine the fundamental host range of two genotypes of the wasp collected from Gr...

  9. INTERNATIONAL MUSEUM DAY 2013 1 Press Contacts: Meredith Kessler, Walker Art Center 612.375.7651 meredith.kessler@walkerart.org

    E-print Network

    Thomas, David D.

    INTERNATIONAL MUSEUM DAY 2013 1 NEWS Press Contacts: Meredith Kessler, Walker Art Center 612 INSTITUTE OF ARTS, AND WEISMAN ART MUSEUM CELEBRATE INTERNATIONAL MUSEUM DAY MAY 18 MUSEUMS TO OFFER FREE of Art Museum Directors' (AAMD) Art Museum Day to coincide with International Museum Day on May 18, 2013

  10. 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 ...

  11. 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.

  12. 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.

  13. 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.

  14. The Lame$^{\\prime}$ Equation for Distance-Redshift in Partially Filled Beam Friedmann-Lema\\^?tre-Robertson-Walker Cosmology

    E-print Network

    R. Kantowski

    2003-08-24

    The differential equation governing distance-redshift for partially filled-beam optics in pressure-freeFriedmann-Lema\\^\\i tre-Robertson-Walker Cosmology (FLRW) is shown to be the Lame$^{\\prime}$ equation. The distance-redshift, $D(z)$, discussed is appropriate for observations in inhomogeneous cosmologies for which lensing by masses external to the observing beam are negligible and for which lensing by transparent matter within the beam can be approximated by a homogeneous mass density expanding with the FLRW background. Some solutions of the derived Lame$^{\\prime}$ equation are given in terms of Weierstrass elliptic integrals. A new simplified and useful expression for filled-beam $D(z)$ in standard flat FLRW is also given.

  15. Towards a better understanding of the impacts of climate change on agricultural productivity and economics in the Walker River Basin

    NASA Astrophysics Data System (ADS)

    Wilson, C. J.; Boyle, D. P.; Garner, C.; Bassett, S.

    2014-12-01

    A significant decrease in seasonal precipitation and a general increase in air temperature over the last three years have resulted in extreme to exceptional drought conditions in much of the southwestern U.S., where water resources are becoming scarcer. In many cases, the impacts of the drought on the agricultural productivity has been severe, as farmers have struggled to maintain the crop water requirements with limited resources available from surface water deliveries and groundwater pumping. In this study, we aim to identify the impacts of climate change on agricultural productivity in the Walker River Basin. In order to develop a better understand of the regional agricultural economic impacts and potential mitigation strategies, we quantify the value of surface water along with supplemental groundwater pumping. Specifically, we analyze changes in potential crop production (both quantity and revenue) and the associated conjunctive use of available surface water and groundwater in both dry and warm climates.

  16. Potential indicator species of climate changes occurring in Québec, Part 1: the small brown lacewing fly Micromusposticus (Walker) (Neuroptera: Hemerobiidae).

    PubMed

    Lesage, Laurent; Savard, Karine; Klimaszewski, Jan

    2013-01-01

    Micromusposticus (Walker) is a small brown lacewing fly rarely collected in Canada and represented in collections by only a limited number of specimens. Indeed, fewer than 50 specimens were captured in Québec and Ontario over the last century, all within a small area delimited by the northern shore of Lake Erie, Ottawa and Montréal. Aylmer, located on the north shore of the Ottawa River, northwest of Ottawa, is a new, most southwestern locality record of this species for Québec. The Aylmer specimens were collected 1-7 days later than any of the known specimens collected elsewhere in Québec or in Ontario, and 16-22 days later than in the neighbouring localities, indicating an apparent phenological shift. PMID:24723766

  17. 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

    2015-01-01

    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 relationships amongst congeners, Pelmatops was well resolved; Ichneumonosoma and Soita were partly resolved, and Pseudopelmatops was unresolved. In addition, a hypothesis about the biology of Pseudopelmatops and its relationship with Sesiidae (Lepidoptera) is discussed. PMID:26623901

  18. How do ants make sense of gravity? A Boltzmann Walker analysis of Lasius niger trajectories on various inclines.

    PubMed

    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 [Formula: see text] rad ([Formula: see text] 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 ([Formula: see text] 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 [Formula: see text] 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

  19. 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

  20. 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 documents the timing of strain transfer from the Imperial fault onto the San Andreas fault through the application of sequence stratigraphy. Evidence shows that the formation of the Salton and Mesquite sub-basins and the associated change of strain partitioning occurred within the last 20-40 k.y., essentially modifying a broader zone of transtension bounding the Imperial and San Andreas faults into two smaller zones of focused extension. The north-central Walker Lane contains a diffuse network of both strike-slip and normal faults, with some degree of strain partitioning characterized by normal faulting to the west along the eastern edge of the Sierra Nevada mountain range, and strike-slip faults to the east that define a diffuse boundary against the Basin and Range proper. A seismic study across the Mount Rose fault zone, bounding the Carson Range near Reno, Nevada, was carried out to investigate slip across a potential low-angle normal fault. A hammer seismic reflection and refraction profile combined with airborne LiDAR (light detection and ranging) imagery highlights fault scarp modification through minor slumping/landslides, providing a better understanding of the nature of slip on this fault. The northeastern margin of the Walker Lane is a region where both "Basin and Range" style normal faults and dextral strike-slip faults contribute to the northward propagation of the Walker Lane (essentially parallel to an equivalent northward propagation of the Mendocino triple junction). Near this intersection lies Pyramid Lake, bounded to the southwest by the dextral Pyramid Lake fault and to the northeast by the normal Lake Range fault. A high-resolution (sub-meter) seismic CHIRP survey collected in 2010 shows intriguing relationships into fault architecture beneath Pyramid Lake. Over 500 line-km of seismic data reveal a polarity flip in basin structure as down-to-the-east motion at the northern end of the Pyramid Lake fault rapidly gives way to down-to-the-west normal motion along the Lake Range fault. Alternating patterns of asymmetric and symmetric

  1. 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. 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 fluid flow and subsequently allow for heterogeneity in the methane migration mechanisms that dominate in marine sediments at a local scale. Incorporating recently acquired 3D seismic data from Walker Ridge to inform the lithologic structure of our modeled reservoir, we show that even with deep adjective sourcing of methane along highly permeable pathways, local hydrate accumulations can be sourced either by diffusive or advective methane flux; advectively-sourced hydrates accumulate evenly in highly permeable strata, while diffusively-sourced hydrates are characterized by thin strata-bound intervals with high clay-sand pore size contrasts.

  2. Placing the 2012-2015 California-Nevada drought into a paleoclimatic context: Insights from Walker Lake, California-Nevada, USA

    NASA Astrophysics Data System (ADS)

    Hatchett, Benjamin J.; Boyle, Douglas P.; Putnam, Aaron E.; Bassett, Scott D.

    2015-10-01

    Assessing regional hydrologic responses to past climate changes can offer a guide for how water resources might respond to ongoing and future climate change. Here we employed a coupled water balance and lake evaporation model to examine Walker Lake behaviors during the Medieval Climate Anomaly (MCA), a time of documented hydroclimatic extremes. Together, a 14C-based shoreline elevation chronology, submerged subfossil tree stumps in the West Walker River, and regional paleoproxy evidence indicate a ~50 year pluvial episode that bridged two 140+ year droughts. We developed estimates of MCA climates to examine the transient lake behavior and evaluate watershed responses to climate change. Our findings suggest the importance of decadal climate persistence to elicit large lake-level fluctuations. We also simulated the current 2012-2015 California-Nevada drought and found that the current drought exceeds MCA droughts in mean severity but not duration.

  3. Glucose metabolism by lymphocytes, macrophages, and tumor cells from Walker 256 tumor-bearing rats supplemented with fish oil for one generation.

    PubMed

    Aikawa, Júlia; Moretto, Karla D; Denes, Francilene; Yamazaki, Ricardo K; Freitas, Fábio A P; Hirabara, Sandro M; Tchaikovski, Osvaldo; Kaelher, Marcos de A; Brito, Gleysson A P; Curi, Rui; Fernandes, Luiz C

    2008-12-01

    Here we investigated the effect of lifelong supplementation of the diet with coconut fat (CO, rich in saturated fatty acids) or fish oil (FO, rich in n-3 polyunsaturated fatty acids) on tumor growth and lactate production from glucose in Walker 256 tumor cells, peritoneal macrophages, spleen, and gut-associated lymphocytes. Female Wistar rats were supplemented with CO or FO prior to mating and then throughout pregnancy and gestation and then the male offspring were supplemented from weaning until 90 days of age. Then they were inoculated subcutaneously with Walker 256 tumor cells. Tumor weight at 14 days in control rats (those fed standard chow) and CO supplemented was approximately 30 g. Supplementation of the diet with FO significantly reduced tumor growth by 76%. Lactate production (nmol h(-1) mg(-1) protein) from glucose by Walker 256 cells in the group fed regular chow (W) was 381.8 +/- 14.9. Supplementation with coconut fat (WCO) caused a significant reduction in lactate production by 1.6-fold and with fish oil (WFO) by 3.8-fold. Spleen lymphocytes obtained from W and WCO groups had markedly increased lactate production (553 +/- 70 and 635 +/- 150) when compared to non-tumor-bearing rats ( approximately 260 +/- 30). FO supplementation reduced significantly the lactate production (297 +/- 50). Gut-associated lymphocytes obtained from W and WCO groups increased lactate production markedly (280 +/- 31 and 276 +/- 25) when compared to non-tumor-bearing rats ( approximately 90 +/- 18). FO supplementation reduced significantly the lactate production (168 +/- 14). Lactate production by peritoneal macrophages was increased by tumor burden but there was no difference between the groups fed the various diets. Lifelong consumption of FO protects against tumor growth and modifies glucose metabolism in Walker tumor cells and lymphocytes but not in macrophages. PMID:18946876

  4. A new species of Gadirtha Walker (Nolidae, Eligminae): a proposed biological control agent of Chinese tallow (Triadica sebifera (L.) Small) (Euphorbiaceae) in the United States

    PubMed Central

    Pogue, Michael G.

    2014-01-01

    Abstract Gadirtha fusca sp. n., is described from Guangxi Province, China. Gadirtha fusca differs in forewing color and pattern, male and female genitalia, and in larval pattern from all other species of Gadirtha. Gadirtha fusca has been evaluated as a potential biological control agent for Chinese tallow (Triadica sebifera (L.) Small, Euphorbiaceae) in the southeastern United States. Adult, male and female genitalia, larva, and pupa are described, illustrated, and compared with Gadirtha impingens Walker. PMID:24624017

  5. A review of "Law, Crime and English Society, 1660-1830" by Norma Landau and "Crime, Gender and Social Order in Early Modern England" by Garthine Walker 

    E-print Network

    Sherman, Donovan

    2010-01-01

    with the Mosaic distinction? in that he moves away from allegory that Spenser uses as his defense and is thus left exposed (316). Norma Landau, ed. Law, Crime and English Society, 1660-1830. Cambridge: CambridgeUniversity Press, 2002. xii + 264 pp. $60....00. Garthine Walker. Crime, Gender and Social Order in Early Modern England. Cambridge: CambridgeUniversity Press, 2003. xvi + 310 pp. $60.00. Review by donovan sherman, university of california, irvine. The tension between postmodern philosophy...

  6. 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

  7. 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.

  8. 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

  9. 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

  10. Identification and classification of toe-walkers based on ankle kinematics, using a data-mining method.

    PubMed

    Armand, Stéphane; Watelain, Eric; Mercier, Moïse; Lensel, Ghislaine; Lepoutre, François-Xavier

    2006-02-01

    A database of 1,736 patients and 2,511 gait analyses was reviewed to identify for trials where the first rocker was absent. A fuzzy c-means algorithm was used to identify sagittal ankle kinematic patterns and three groups were identified. The first showed a progressive dorsiflexion during the stance phase, while the second had a short-lived dorsiflexion, followed by a progressive plantarflexion. The third group exhibited a double bump pattern, moving successively from a short-lived dorsiflexion to a short-lived plantarflexion and then returning to a further short-lived dorsiflexion before ending with plantarflexion until toe-off. The three patterns were linked to different neurological conditions. Myopathy, neuropathy and arthogryposis essentially revealed group 1 patterns, whereas idiopathic toe-walkers mainly displayed group 2 patterns. Cerebral palsy patients, however, were relatively homogeneously distributed amongst the three groups. Able-bodied subjects walking on their toes showed a high proportion of unclassifiable ankle patterns, due to a variable gait whilst toe walking. Despite the variety of neurological conditions included in this meta-analysis repeatable biomechanical patterns appeared that could influence therapeutic management. PMID:16399521

  11. Effects of Fraxinellone on the Midgut Enzyme Activities of the 5th Instar Larvae of Oriental Armyworm, Mythimna separata Walker

    PubMed Central

    Lv, Min; Wu, Wenjun; Liu, Huixia

    2014-01-01

    Isolated from Dictamnus dasycarpus Turcz., fraxinellone exhibited multiple bioactivities against insects. In the present paper, the changes of digestive enzymes and detoxification enzymes of Mythimna separata Walker (5th instar larvae), treated with fraxinellone, were investigated. Compared with those of the control, the ?-amylase activity of the fraxinellone-treated 5th instar larvae was inhibited, whereas the level of their protease activity was increased. Based upon further studies on the specific proteases, the levels of the active alkaline trypsin-like enzyme (BApNA as the substrate) and the chymotrypsin-like enzyme (BTEE as the substrate) activities of the treated larvae were declined; however, the level of activity of the weak alkaline trypsin-like enzyme (TAME as the substrate) of the treated ones was increased. Meanwhile, the activities of two detoxification enzymes, such as carboxylesterase (CarE) and glutathione S-transferase (GST), of the treated larvae were increased to some extent, but the activities of NADPH-P450 reductase and O-demethylase of the treated ones declined. Therefore, protease (especially the weak alkaline trypsin-like enzyme), CarE and GST played important roles in the metabolism of fraxinellone in the midgut of Mythimna separata (M. separata). PMID:25216084

  12. 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.

  13. Effects of Fraxinellone on the midgut enzyme activities of the 5th Instar Larvae of Oriental Armyworm, Mythimna separata walker.

    PubMed

    Lv, Min; Wu, Wenjun; Liu, Huixia

    2014-09-01

    Isolated from Dictamnus dasycarpus Turcz., fraxinellone exhibited multiple bioactivities against insects. In the present paper, the changes of digestive enzymes and detoxification enzymes of Mythimna separata Walker (5th instar larvae), treated with fraxinellone, were investigated. Compared with those of the control, the ?-amylase activity of the fraxinellone-treated 5th instar larvae was inhibited, whereas the level of their protease activity was increased. Based upon further studies on the specific proteases, the levels of the active alkaline trypsin-like enzyme (BApNA as the substrate) and the chymotrypsin-like enzyme (BTEE as the substrate) activities of the treated larvae were declined; however, the level of activity of the weak alkaline trypsin-like enzyme (TAME as the substrate) of the treated ones was increased. Meanwhile, the activities of two detoxification enzymes, such as carboxylesterase (CarE) and glutathione S-transferase (GST), of the treated larvae were increased to some extent, but the activities of NADPH-P450 reductase and O-demethylase of the treated ones declined. Therefore, protease (especially the weak alkaline trypsin-like enzyme), CarE and GST played important roles in the metabolism of fraxinellone in the midgut of Mythimna separata (M. separata). PMID:25216084

  14. 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) = ?(b)/|?(5)|, where M(P) is the effective (normalized) Planck mass, ?(5) is the five-dimensional cosmological constant, and ?(b) is the sum of the 3-brane tension V and the matter density ?. Although the range of variation in ?(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8?M(P)(2))(-1) is satisfied when the ratio V/? ? 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

  15. A fully covariant information-theoretic ultraviolet cutoff for scalar fields in expanding Friedmann Robertson Walker spacetimes

    NASA Astrophysics Data System (ADS)

    Kempf, A.; Chatwin-Davies, A.; Martin, R. T. W.

    2013-02-01

    While a natural ultraviolet cutoff, presumably at the Planck length, is widely assumed to exist in nature, it is nontrivial to implement a minimum length scale covariantly. This is because the presence of a fixed minimum length needs to be reconciled with the ability of Lorentz transformations to contract lengths. In this paper, we implement a fully covariant Planck scale cutoff by cutting off the spectrum of the d'Alembertian. In this scenario, consistent with Lorentz contractions, wavelengths that are arbitrarily smaller than the Planck length continue to exist. However, the dynamics of modes of wavelengths that are significantly smaller than the Planck length possess a very small bandwidth. This has the effect of freezing the dynamics of such modes. While both wavelengths and bandwidths are frame dependent, Lorentz contraction and time dilation conspire to make the freezing of modes of trans-Planckian wavelengths covariant. In particular, we show that this ultraviolet cutoff can be implemented covariantly also in curved spacetimes. We focus on Friedmann Robertson Walker spacetimes and their much-discussed trans-Planckian question: The physical wavelength of each comoving mode was smaller than the Planck scale at sufficiently early times. What was the mode's dynamics then? Here, we show that in the presence of the covariant UV cutoff, the dynamical bandwidth of a comoving mode is essentially zero up until its physical wavelength starts exceeding the Planck length. In particular, we show that under general assumptions, the number of dynamical degrees of freedom of each comoving mode all the way up to some arbitrary finite time is actually finite. Our results also open the way to calculating the impact of this natural UV cutoff on inflationary predictions for the cosmic microwave background.

  16. 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

  17. Targeted disruption of the Walker–Warburg syndrome gene Pomt1 in mouse results in embryonic lethality

    PubMed Central

    Willer, Tobias; Prados, Belén; Falcón-Pérez, Juan Manuel; Renner-Müller, Ingrid; Przemeck, Gerhard K. H.; Lommel, Mark; Coloma, Antonio; Valero, M. Carmen; de Angelis, Martin Hrabé; Tanner, Widmar; Wolf, Eckhard; Strahl, Sabine; Cruces, Jesús

    2004-01-01

    O-mannosylation is an important protein modification in eukaryotes that is initiated by an evolutionarily conserved family of protein O-mannosyltransferases. The first mammalian protein O-mannosyltransferase gene described was the human POMT1. Mutations in the hPOMT1 gene are responsible for Walker–Warburg syndrome (WWS), a severe recessive congenital muscular dystrophy associated with defects in neuronal migration that produce complex brain and eye abnormalities. During embryogenesis, the murine Pomt1 gene is prominently expressed in the neural tube, the developing eye, and the mesenchyme. These sites of expression correlate with those in which the main tissue alterations are observed in WWS patients. We have inactivated a Pomt1 allele by gene targeting in embryonic stem cells and produced chimeras transmitting the defect allele to offspring. Although heterozygous mice were viable and fertile, the total absence of Pomt1–/– pups in the progeny of heterozygous intercrosses indicated that this genotype is embryonic lethal. An analysis of the mutant phenotype revealed that homozygous Pomt1–/– mice suffer developmental arrest around embryonic day (E) 7.5 and die between E7.5 and E9.5. The Pomt1–/– embryos present defects in the formation of Reichert's membrane, the first basement membrane to form in the embryo. The failure of this membrane to form appears to be the result of abnormal glycosylation and maturation of dystroglycan that may impair recruitment of laminin, a structural component required for the formation of Reichert's membrane in rodents. The targeted disruption of mPomt1 represents an example of an engineered deletion of a known glycosyltransferase involved in O-mannosyl glycan synthesis. PMID:15383666

  18. 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.

  19. 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.

  20. 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.

  1. 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 improves our ability to compare results to geologic fault slip rates. Modeling the kinematics on this scale has the advantages of 1) reducing the impact of poorly constrained boundaries on small geographically limited models, 2) consistent modeling of rotations across major structural step-overs near the Mina deflection and Carson domain, 3) tracking the kinematics of the south-to-north varying budget of Walker Lane deformation by solving for extension in the Basin and Range to the east, and 4) using a contiguous SNGV as a uniform western kinematic boundary condition. We compare contemporary deformation to geologic slip rates and longer term rotation rates estimated from rock paleomagnetism. GPS-derived block rotation rates are somewhat dependent on model regularization, but are generally within 1° per million years, and tend to be slower than published paleomagnetic rotations rates. GPS data, together with neotectonic and rock paleomagnetism studies provide evidence that the relative importance of Walker Lane block rotations and fault slip continues to evolve, giving way to a more through-going system with slower rotation rates and higher slip rates on individual faults.

  2. Influence of inherited features on the boundaries and fault patterns of the Transtensional Gulf of California to Walker Lane/Basin and Range

    NASA Astrophysics Data System (ADS)

    Umhoefer, P. J.

    2012-12-01

    The Basin and Range (BR) includes a continuous belt from the Gulf of California extensional province of Mexico through Southwestern USA to the Walker Lane and northern BR. This includes the core extensional to transtensional belt that lies east of the Pacific - North America (PAC-NAM) plate boundary. Much of the BR is the result of the westward to northwestward motion of the Baja California and Sierra Nevada microplates away from North America during PAC-NAM motion. These microplates are parts of the Cretaceous batholith and the eastern edge of the batholiths define the western edge of the BR. The transtensional faulting of eastern Baja California and Walker Lane are remarkably similar and show down-to-the-east normal faults along the batholith boundary. To the east are linked normal and strike-slip faults, the latter striking from parallel to relative motion of the microplates to nearly parallel to the batholith boundary. The Walker Lane boundary has domains of strain partitioning and other domains with northwesterly regional shear and no partitioning. Why certain areas are partitioned is not known, but secondary inherited structures may play a role. The eastern edge of the BR is dominated by the Sierra Madre Occidental and the Colorado Plateau and is more variable in faulting patterns because the boundary is more variable in shape, the previous geologic history is more complex, and most extension occurred just before and in the early stage of PAC-NAM motion. The Sierra Madre is likely underlain by a large batholith formed during caldera eruptions in the Oligocene; this batholith roughly parallels the Cretaceous batholith on the Baja California microplate and the SE BR is dominated by early extensional faults. The southern and western edges of the Colorado Plateau form the eastern boundary of the BR in the north with mainly ENE-directed core complexes in pre-17-15 Ma PAC-NAM history. Extension near Las Vegas 17 - ~10 Ma was westward and the inherited NE-oriented Wasatch line - Laramide boundary created west-facing conjugate fault wedges in an overall transtensional system. At ~8 Ma, there was a switch from extension to transtension and faulting localized to the western side of the BR as PAC-NAM motion became more northwesterly; after 8 Ma, northwestward transtension dominated Walker Lane to Gulf of California. This belt is a classic example of earlier convergent tectonics controlling the geometries of later transtensional faulting.

  3. 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 ?- and ?-naphtyl acetate and glutathione S-transferase using CDNB and DCNB increased 1-12h post-treatment. Activities of aspartate aminotransferase, alanine aminotransferase, ?-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 able to decrease survival and biological performance of C. suppressalis via intervening in intermediary metabolism but the given results showed incompatibility of the IGR with possible microbial control. PMID:26615153

  4. The Relationship of Walking Intensity to Total and Cause-Specific Mortality. Results from the National Walkers’ Health Study

    PubMed Central

    Williams, Paul T.; Thompson, Paul D.

    2013-01-01

    Purpose Test whether: 1) walking intensity predicts mortality when adjusted for walking energy expenditure, and 2) slow walking pace (?24-minute mile) identifies subjects at substantially elevated risk for mortality. Methods Hazard ratios from Cox proportional survival analyses of all-cause and cause-specific mortality vs. usual walking pace (min/mile) in 7,374 male and 31,607 female recreational walkers. Survival times were left censored for age at entry into the study. Other causes of death were treated as a competing risk for the analyses of cause-specific mortality. All analyses were adjusted for sex, education, baseline smoking, prior heart attack, aspirin use, diet, BMI, and walking energy expenditure. Deaths within one year of baseline were excluded. Results The National Death Index identified 1968 deaths during the average 9.4-year mortality surveillance. Each additional minute per mile in walking pace was associated with an increased risk of mortality due to all causes (1.8% increase, P=10-5), cardiovascular diseases (2.4% increase, P=0.001, 637 deaths), ischemic heart disease (2.8% increase, P=0.003, 336 deaths), heart failure (6.5% increase, P=0.001, 36 deaths), hypertensive heart disease (6.2% increase, P=0.01, 31 deaths), diabetes (6.3% increase, P=0.004, 32 deaths), and dementia (6.6% increase, P=0.0004, 44 deaths). Those reporting a pace slower than a 24-minute mile were at increased risk for mortality due to all-causes (44.3% increased risk, P=0.0001), cardiovascular diseases (43.9% increased risk, P=0.03), and dementia (5.0-fold increased risk, P=0.0002) even though they satisfied the current exercise recommendations by walking ?7.5 metabolic equivalent (MET)-hours per week. Conclusions The risk for mortality: 1) decreases in association with walking intensity, and 2) increases substantially in association for walking pace ?24 minute mile (equivalent to <400m during a six-minute walk test) even among subjects who exercise regularly. PMID:24260542

  5. 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) than the long-term mean. Future changes in the incidence of storm events, as well as the number and duration of droughts, have the potential to significantly alter watershed nutrient losses. Our analysis indicates that changing climates can differentially affect watershed element cycles either through changes in biogeochemical process rates or through changes in catchment hydrology. Furthermore, climate change can include both long-term trending in mean climate variables, as well as changes in the frequency and intensity of storms and droughts, with each of these types of change having distinct effects on the biological and geochemical processes governing different solutes.

  6. Interview with John Walker

    E-print Network

    Walker, John E.

    2008-08-13

    group of people - Francis Crick, Sidney Brenner, Hugh Huxley, Fred Sanger, Max Perutz and Aaron Klug; the ones who shone publicly were Crick and Brenner; they dominated the seminar discussions; Crick left soon after to join the Salk Institute; Perutz...

  7. "Frog" Walker & Jim Calvert 

    E-print Network

    Unknown

    2011-08-17

    inoculation in frogs (Xenopus sp.). Oral immunization is a novel approach to eliciting immune responses in Xenopus. I propose that IgX will increase with oral inoculation compared to intraperitoneal injection. This would be the first demonstration of class...

  8. 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 ...

  9. Effect of fish oil supplementation for 2 generations on changes in macrophage function induced by Walker 256 cancer cachexia in rats.

    PubMed

    Folador, Alessandra; Hirabara, Sandro M; Bonatto, Sandro J R; Aikawa, Júlia; Yamazaki, Ricardo K; Curi, Rui; Fernandes, Luiz C

    2007-01-15

    The effect of coconut fat (rich in medium saturated fatty acids) or fish oil (rich in omega-3 polyunsaturated fatty acids) supplementation for 2 generations on tumor growth, cancer cachexia, animal survival and macrophage function was investigated in Walker 256 tumor-bearing rats. Female Wistar rats were supplemented with coconut fat or fish oil prior to mating and then throughout pregnancy and gestation. Both supplementations were daily and orally given at 1 g per kg body weight as a single bolus. Same treatment was performed by the 2 following generations. At 90 days of age, male offspring (50%) from F2 generation were subcutaneously inoculated with 2 x 10(7) Walker 256 tumor cells. At 14 days after tumor implantation, rats not supplemented displayed cancer cachexia characterized by loss of body weight, hypoglycemia, hyperlacticidemia, hypertriglyceridemia, decreased food intake and depletion of glycogen stores in the liver and skeletal muscles. Supplementation with coconut fat did not affect these parameters. However, supplementation with fish oil decreased tumor growth (59%), prevented body weight loss and food intake reduction and attenuated cancer cachexia. In addition, fish oil increased animal survival up to 20 days (from 25% in rats not supplemented to 67% in rats supplemented with fish oil) and improved macrophage function characterized by increased phagocytosis capacity and production of hydrogen peroxide and nitric oxide. These results suggest that fish oil supplementation for 2 generations improves macrophage function in association to reduced tumor growth and attenuated cancer cachexia, maintaining food intake and increasing animal survival. PMID:17066422

  10. 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. PMID:23143316

  11. 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.

  12. 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.

  13. Hammond, W.C., Kreemer, C., and Blewitt, G., 2009, Geodetic constraints on contemporary deformation in the northern Walker Lane: 3. Central Nevada seismic belt postseismic relaxation, in Oldow, J.S., and Cashman, P.H., eds., Late Cenozoic Structure and Ev

    E-print Network

    Blewitt, Geoffrey

    .S., and Cashman, P.H., eds., Late Cenozoic Structure and Evolution of the Great Basin­Sierra Nevada Transition deformation in the northern Walker Lane: 3. Central Nevada seismic belt postseismic relaxation, in Oldow, J in the northern Walker Lane: 3. Central Nevada seismic belt postseismic relaxation William C. Hammond* Corné

  14. 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 localities also reveals kinematic constraints for the boundary between the Sierra Nevada and central Walker Lane belt. The section at Sonora Peak, CA, within the stable Sierra Nevada microplate, yields a locality mean direction for these rocks indistinguishable from the expected direction for the late Miocene. The two other study localities, Grouse Meadow and Burcham Creek, lie within the western Walker Lane Belt, east of the Sierra Nevada range front fault zone. Results from these latter localities reveal 10°-20° of vertical axis rotation of fault-bounded blocks of the western Walker Lane since emplacement of the Stanislaus Group. These results are obtained relative to a variety of datums - by averaging secular variation, by comparing locality mean directions from one place to another, and by comparing unit mean directions for the extensive e ignimbrites from one place to another. These results allow explicit delineation of the kinematic boundary between stable Sierra Nevada and the Walker Lane and geometrical calculation of total strain accommodated by these rotations.

  15. 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

    As the earth's population, industry, and agricultural systems continue to expand and increase demand for limited hydrologic resources, developing better tools for monitoring, analyzing and perhaps even predicting decadal variations in precipitation will enable the climate community to better inform important policy and management decisions. To this end, in support of the development and humanitarian relief efforts of the US Agency for International Development, USGS, NOAA, UC Santa Barbara, and NASA scientists have been exploring global precipitation trends using observations and new ensembles of atmospheric general circulation model (AGCM) simulations from the ECHAM5, GFSv2, CAM4 and GMAO models. This talk summarizes this work, and discusses how combined analyses of AGCM simulations and observations might lead to credible decadal projections, for some regions and seasons, based on the strength of the Indo-Pacific warming signal. Focusing on the late boreal spring, a critical period for food insecure Africa, we begin by linearly decomposing 1900-2012 sea surface temperatures (SST) into components loading strongly in the Indo-Western Pacific and Eastern Pacific. Eastern Pacific (EP) SST variations are based on regressions with three time series: the first and second principal components of equatorial Pacific SST and the Pacific Decadal Oscillation. These influences are removed from Indo-Pacific SSTs, and the Indo-Western Pacific (IWP) SST variations are defined by the 1st principal component of the residuals, which we refer to as the Indo-West Pacific Warming Signal (IWPWS). The pattern of IWPWS SST changes resembles recent assessments of centennial warming, and identifies rapid warming in the equatorial western Pacific and north and south Pacific convergence zones. The circulation impacts of IWP and EP SST forcing are explored in two ways. First, assuming linear SST forcing relationships, IWP and EP decompositions of ECHAM5, GFS, CAM4 and GMAO AGCM simulations are 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.

  16. Mach's principle: Exact frame-dragging via gravitomagnetism in perturbed Friedmann-Robertson-Walker universes with K=(±1,0)

    NASA Astrophysics Data System (ADS)

    Schmid, Christoph

    2009-03-01

    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 ??gyro of local gyroscopes, which in turn gives the operational definition of the gravitomagnetic field: B?g?-2??gyro. The gravitomagnetic field is caused by energy currents J?? via the momentum constraint, Einstein’s G0^i^ equation, (-?+?2)A?g=-16?GNJ?? with B?g=curlA?g. This equation is analogous to Ampère’s law, but it holds for all time-dependent situations. ? is the de Rham-Hodge Laplacian, and ?=-curlcurl for the vorticity sector in Riemannian 3-space.—In the solution for an open universe the 1/r2-force of Ampère is replaced by a Yukawa force Y?(r)=(-d/dr)[(1/R)exp?(-?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?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 cosmic time, and ?2=-4(dH/dt). Analogous results hold in closed FRW universes and in Einstein’s closed static universe.—We list six fundamental tests for the principle formulated by Mach: all of them are explicitly fulfilled by our solutions.—We show that only energy currents in the toroidal vorticity sector with ?=1 can affect the precession of gyroscopes. We show that the harmonic decomposition of toroidal vorticity fields in terms of vector spherical harmonics X??m- has radial functions which are form-identical for the 3-sphere, the hyperbolic 3-space, and Euclidean 3-space, and are form-identical with the spherical Bessel-, Neumann-, and Hankel functions.—The Appendix gives the de Rham-Hodge Laplacian on vorticity fields in Riemannian 3-spaces by equations connecting the calculus of differential forms with the curl notation. We also give the derivation the Weitzenböck formula for the difference between the de Rham-Hodge Laplacian ? and the “rough” Laplacian ?2 on vector fields.

  17. 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 cosmic time, and {mu}{sup 2}=-4(dH/dt). Analogous results hold in closed FRW universes and in Einstein's closed static universe.--We list six fundamental tests for the principle formulated by Mach: all of them are explicitly fulfilled by our solutions.--We show that only energy currents in the toroidal vorticity sector with l=1 can affect the precession of gyroscopes. We show that the harmonic decomposition of toroidal vorticity fields in terms of vector spherical harmonics X-vector{sub lm}{sup -} has radial functions which are form-identical for the 3-sphere, the hyperbolic 3-space, and Euclidean 3-space, and are form-identical with the spherical Bessel-, Neumann-, and Hankel functions. - The Appendix gives the de Rham-Hodge Laplacian on vorticity fields in Riemannian 3-spaces by equations connecting the calculus of differential forms with the curl notation. We also give the derivation the Weitzenboeck formula for the difference between the de Rham-Hodge Laplacian {delta} and the ''rough'' Laplacian {nabla}{sup 2} on vector fields.

  18. 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 paleomagnetism, we show the dated outcrops to be Tollhouse Flat Member, substantially improving age constraints on EVT.

  19. Influence of transarterial chemoembolization on angiogenesis and expression of vascular endothelial growth factor and basic fibroblast growth factor in rat with Walker-256 transplanted hepatoma: An experimental study

    PubMed Central

    Li, Xin; Feng, Gan-Sheng; Zheng, Chuan-Sheng; Zhuo, Chen-Kai; Liu, Xi

    2003-01-01

    AIM: After transarterial chemoembolization (TACE), the residual cancer cells are under extensive hypoxic or even anoxic environment. Hypoxia can lead to adaptive responses. For example, angiogenesis will help these cells survive. In this study, we examined the effect of TACE on angiogenesis and expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF) and to assess their relevance to Walker-256 transplanted hepatoma. METHODS: Male Wistar rats were inoculated with Walker-256 tumor in the left lobe of liver. Angiography and transarterial chemoembolization were performed at d14 after transplantation. Sixty rats bearing walker-256 transplanted hepatoma were randomly divided into control group, arterial infusion group and TACE group. Each group consisted of twenty rats. Normal saline, 5-FU, 5-FU and lipiodol were infused through hepatic artery respectively. Two weeks after the infusion, staining of factor VIII, VEGF and b-FGF was performed by immunohistochemistry method in routine paraffin-embeded sections. Microvessel density (MVD) was counted in endothelial cells with positive factor VIII. Their expression levels were analyzed in conjunction with the pathologic features. RESULTS: While a smaller tumor volume was found in TACE group (F = 37.818, P < 0.001), no statistical differences between MVD and expression of VEGF and b-FGF were found among the 3 groups. MVD of the control group, chemotherapy group and chemoemoblization group was 80.84 ± 24.24, 83.05 ± 20.29 and 85.20 ± 23.91 (F = 0.193, P = 0.873), respectively. The positive expression of VEGF and b-FGF was 75%, 75%, 85% (?² = 0.449, P = 0.799) and 30%, 25%, 30% (?² = 0.141, P = 0.922), respectively. Statistical analysis revealed a positive correlation between the expression of VEGF and MVD (r = 0.552, P < 0.001). CONCLUSION: There has been little influence of lipiodol chemoembolization on the formation of tumor angiogenesis, but the development of neovascularization and expression of VEGF play important roles in establishment of collateral circulation and reconstruction of blood supply of residual cancer tissue. PMID:14606073

  20. 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...

  1. Department Name Website Internship Link Internship Coordinator Internship Coord Email Department Requirements Accountancy & Business Law http://csb.uncw.edu/acg/ http://csb.uncw.edu/serviceLearning/internships.htm Teresa Walker

    E-print Network

    Olszewski Jr., Edward A.

    Department Name Website Internship Link Internship Coordinator Internship Coord Email Department Requirements Accountancy & Business Law http://csb.uncw.edu/acg/ http://csb.uncw.edu/serviceLearning/internships.htm Teresa Walker Loraine Lee (accounting) - Leel@uncw.edu Walkert@uncw.edu Public Accounting Internship

  2. [16] J. J. Dongarra, R. van de Geijn, and D. W. Walker. A look at Scalable Linear Algebra Libraries. In Proceedings of the 1992 Scalable High Performance Computing Conference,

    E-print Network

    Walker, David W.

    ­ 31 ­ [16] J. J. Dongarra, R. van de Geijn, and D. W. Walker. A look at Scalable Linear Algebra Press, 1992. [17] J. J. Dongarra and R. A. van de Geijn. Two Dimensional Basic Linear Algebra Communi. [18] J. J. Dongarra, R. A. van de Geijn, and R. C. Whaley. BLACS User's Guide. Technical report

  3. 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. PMID:25633673

  4. Resolving the discrepancy between geodetic and geologic estimates of fault slip rates in the central Walker Lane: A block modeling approach

    NASA Astrophysics Data System (ADS)

    Bormann, J. M.; Hammond, W. C.; Kreemer, C. W.; Wesnousky, S. G.; Blewitt, G.

    2011-12-01

    The Walker Lane is a ~100 km wide zone of active intracontinental transtensional faulting which accommodates 8-10 mm/yr of Pacific-North American relative dextral plate motion between the northwest translating Sierra Nevada/Great Valley microplate and the west-northwestward extending Basin and Range in the western United States. Between the Walker Lake and Lake Tahoe basins (~38.5-39.5° N latitude), the Walker Lane lacks strike-slip faults optimally oriented to accommodate northwest-directed dextral shear. In this region, geologic studies of active faulting show that Quaternary tectonic deformation occurs in a northwest-trending series of north-striking, normal fault-bounded basins. Geomorphic and paleoseismic studies of the major basin-bounding faults estimate normal slip rates between ~0.3-2.5 mm/yr. However, the combined geologically determined slip rates for major faults in the central Walker Lane are not sufficient to accommodate the geodetically observed northwest-directed dextral shear. To address this discrepancy, we model crustal deformation using GPS data from the EarthScope Plate Boundary Observatory and other continuous GPS networks together with data from UNR's semi-continuous network MAGNET. We estimate rates of fault slip and vertical axis block rotation using an elastic block model. Comparisons between geodetically and geologically estimated slip rates on the major basin-bounding normal faults show that 7 out of 8 geodetic estimates agree with geologic estimates to within uncertainties. However, models constrained solely by GPS data predict dextral slip rates on the basin-bounding normal faults that are greater than or equal to the normal slip rates, between 0.3-2.0 mm/yr. This prediction is not substantiated by paleoseismic and geomorphic fault studies, suggesting a discrepancy between the geologic and geodetic datasets. Block models that are forced to strictly adhere to geologically observed fault slip style constraints (i.e. no oblique slip on normal faults) predict clockwise vertical axis rotations for normal fault-bounded blocks between 1-4.5°/My, which are double the rates predicted by the GPS-based model. The resulting RMS residual velocities are significantly larger than the best fitting geodetic model, indicating a poor fit to the GPS data. Models that loosely impose geologic style constraints predict small amounts of oblique shear on normal faults and somewhat increased rates of clockwise vertical axis block rotation. These models result in RMS residual velocities only slightly larger than the best fitting geodetic model. This research suggests that resolution between the two datasets may lie in the combination of low magnitude oblique dextral slip on basin-bounding normal faults with clockwise vertical axis rotations of normal fault bounded blocks.

  5. 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.

  6. Natural-product-based insecticidal agents 14. Semisynthesis and insecticidal activity of new piperine-based hydrazone derivatives against Mythimna separata Walker in vivo.

    PubMed

    Qu, Huan; Yu, Xiang; Zhi, Xiaoyan; Lv, Min; Xu, Hui

    2013-10-15

    In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, twenty-six new piperine-based hydrazone derivatives were synthesized from piperine, an alkaloid isolated from Piper nigrum Linn. The single-crystal structures of 6c, 6q and 6w were unambiguously confirmed by X-ray crystallography. Their insecticidal activity was evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo. Especially compounds 6b, 6i and 6r, the final mortality rates of which, at the concentration of 1 mg/mL, were 62.1%, 65.5% and 65.5%, respectively, exhibited more pronounced insecticidal activity compared to toosendanin at 1 mg/mL, a commercial botanical insecticide isolated from Melia azedarach. It suggested that introduction of the substituents at the C-2 position on the phenyl ring of the hydrazone derivatives was important for their insecticidal activity. PMID:24018189

  7. Investigation of the Origins of Modern Firmgrounds in Walker Lake, Nevada: Implications for Lacustrine Climate Records and Hardgrounds in the Rock Record

    NASA Astrophysics Data System (ADS)

    Beckerman, L. G.; Lau, K. V.; Stewart, L. C.; Loyd, S. J.; Ibarra, Y.; Corsetti, F. A.; Stevenson, B. S.; Stamps, B. W.; Spear, J. R.

    2014-12-01

    Walker Lake, Nevada, contains locally abundant Pleistocene and Holocene carbonate structures, including tufas, stromatolites, and lithified carbonate hardgrounds. Hardgrounds are classically interpreted as forming via geobiological processes in shallow sediments. To better understand the origins of ancient hardgrounds, we investigated modern firmgrounds which we hypothesized to be incipient hardgrounds. The studied firmgrounds were brown, 1-2 cm thick with a mm-scale white or brown crust, cohesive enough to retain sharp erosional features, and were located on the western shoreline where alluvial fans enter the lake. We analyzed the elemental composition of the lakewater and porewaters in order to model mineral saturation states under lake conditions. In addition, we analyzed 16S rRNA gene diversity of the firmgrounds, porewater of adjacent sediments, and lakewater to investigate potential biological involvement. This, combined with SEM imaging, XRD analyses, and EDS analyses indicate that the firmgrounds are likely dominated by clays and granitic minerals rather than carbonate like the ancient hardgrounds. We suggest that Walker Lake firmgrounds are formed by weathering of unstable granitic minerals with no clear biological influence, likely resulting from physio-chemical processes related to groundwater-lake water mixing. Such firmgrounds may undergo subsequent replacement by calcium carbonate to form hardgrounds, resulting in carbonates with ?13C and ?18O compositions that do not reflect the lake water in which they formed. Given the apparent influence of groundwater on their formation, our work suggests that caution should be used when interpreting lacustrine hardground isotopic records as indicators of lakewater chemistry and climate.

  8. Toward a better understanding of the impacts from climate change on a modern agricultural system in the Walker River Basin: A paleo perspective

    NASA Astrophysics Data System (ADS)

    Wilson, C. J.; Barth, C.; Boyle, D. P.; Garner, C.; Bassett, S.

    2013-12-01

    As the Earth continues to warm from increasing emissions of CO2 and other greenhouse gasses, many different research groups continue using global climate models to better understand and predict the associated spatial and temporal changes in temperature and precipitation patterns on the landscape. Although the models are generally in agreement that, as the emissions continue the planet will continue to warm, there is still considerable disagreement and uncertainty among the models on the changes in precipitation patterns in many regions, particularly in the western U.S. where significant agricultural activities exist that are extremely sensitive to changes in precipitation. There is, however, a significant body of research that has focused on further understanding how the climate has changed in the past through paleolake studies in the arid and semiarid regions of the western U.S. and other similar locations throughout the world. In particular, several studies have estimated reductions in annual precipitation by as much as 60% of modern values during the Medieval Climatic Anomaly (MCA). In this study, we utilize a detailed, high spatial resolution hydrologic model of the Walker River Basin to conduct a number of climate change studies aimed at assessing the impacts of a wide range of changes in climate variables (i.e. precipitation and temperature) on important agricultural variables (e.g., surface water irrigation, ground water pumping, crop yield, etc.) from the watershed to the farm scale. Specifically, we explore the impacts and resiliency of the modern Walker River watershed and agricultural systems under the climatic conditions that existed during the MCA and those that are forecasted to occur in the future based on popular emission studies using global climate models.

  9. 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 include the 1934 M 6.5 Excelsior Mountains event south of Mina, NV, and the 1932 M 7.1 Cedar Mountains earthquake east of the Pilot Mountains. Another persistent feature in the seismicity is an ~40 km long arcuate distribution of activity extending from approximately Queen Valley, north of the White Mountains, to Mono Lake that appears to reflect a southwestern boundary to northeast-striking structures in the MD. Here we develop high-precision relocations of instrumental seismicity in the MD from 1984 through 2012, including relocations of the 2004 sequence, and account for the historical seismic record. MT solutions from published reports and computed from recent M 3.5+ earthquakes as well as available and developed short-period focal mechanisms are compiled to evaluate the stress field to assess mechanisms of slip accommodation. Based on the complex distribution of fault orientations, the stress field varies locally northward from the SWL throughout the MD; however, in many cases, fault plane alignments can be isolated from high-precision locations, providing better constraints on stress and slip orientations.

  10. 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 impermeable boundaries. The main reason for the reduced productivity is water influx from the surrounding strata; a secondary cause is gas escape into the overburden. The results dictate that in order to reliably estimate production potential, permeability of the surroundings has to be included in a model.

  11. Inferior cerebellar hypoplasia resembling a Dandy-Walker-like malformation in purebred Eurasier dogs with familial non-progressive ataxia: a retrospective and prospective clinical cohort study.

    PubMed

    Bernardino, Filipa; Rentmeister, Kai; Schmidt, Martin J; Bruehschwein, Andreas; Matiasek, Kaspar; Matiasek, Lara A; Lauda, Alexander; Schoon, Heinz A; Fischer, Andrea

    2015-01-01

    Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5-6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance. PMID:25668516

  12. Decreased tumor growth in Walker 256 tumor-bearing rats chronically supplemented with fish oil involves COX-2 and PGE2 reduction associated with apoptosis and increased peroxidation.

    PubMed

    Mund, Rogéria C; Pizato, Nathalia; Bonatto, Sandro; Nunes, Everson A; Vicenzi, Thiago; Tanhoffer, Ricardo; de Oliveira, Heloisa H P; Curi, Rui; Calder, Philip C; Fernandes, Luiz C

    2007-02-01

    Many studies have shown that addition of fish oil (FO) to the diet reduces tumor growth but the mechanism(s) of action involved is (are) still unknown. In this study, we examine some possible mechanisms in tumor-bearing rats chronically supplemented with FO. Male Wistar rats (21 days old) were fed with regular chow and supplemented with coconut or FO (1g/kg body weight) until they reached 70 days of age. Then, they were inoculated with a suspension of Walker 256 ascitic tumor cells (2 x 10(7)ml) and after 14 days they were killed. Supplementation with FO resulted in significantly lower tumor weight, greater tumor cell apoptosis, lower ex vivo tumor cell proliferation, a higher tumor content of lipid peroxides, lower expression of cyclooxygenase-2 (COX-2) in tumor tissue and a lower plasma concentration of prostaglandin E2 than observed in rats fed regular chow or supplemented with coconut oil. These results suggest that reduction of tumor growth by FO involves an increase in apoptosis and of lipid peroxidation in tumor tissue, with a reduction in tumor cell proliferation ex vivo, COX-2 expression and PGE2 production. Thus, FO may act simultaneously through multiple effects to reduce tumor growth. Whether these effects are connected through a single underlying mechanism remains to be seen. PMID:17234396

  13. Prenatal Diagnosis of Walker–Warburg Syndrome Using Single Nucleotide Polymorphism Array: A Clinical Experience from Three Related Palestinian Families with Congenital Hydrocephalus

    PubMed Central

    Abumansour, Iman S.; Al Sulmi, Eman; Chodirker, Bernard N.; Hunt, Jennifer C.

    2015-01-01

    Background?Congenital hydrocephalus is a common and often disabling disorder. Various syndromic forms of hydrocephalus have been reported in the Palestinian population including Walker–Warburg syndrome (WWS), Carpenter syndrome, and Meckel syndrome. Aim?In this report we discuss the antenatal diagnosis of congenital hydrocephalus in three related Palestinian families. Method?Single nucleotide polymorphism (SNP) array was performed prenatally for the third affected fetus. Results?A diagnosis of WWS was found and molecular testing revealed a known pathogenic mutation in the POMT2 gene. An affected fetus from the other family was diagnosed and tested postnatally in light of this finding. Testing of another affected stillborn offspring was performed and revealed the same mutation. Conclusions?Here, we show that the use of prenatal SNP array testing can be helpful in elucidating the etiology of congenital hydrocephalus and in guiding appropriate perinatal care. Also, testing for this specific POMT2 mutation should be considered in cases of prenatally detected hydrocephalus in Palestinian families. PMID:26495167

  14. Inferior Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation in Purebred Eurasier Dogs with Familial Non-Progressive Ataxia: A Retrospective and Prospective Clinical Cohort Study

    PubMed Central

    Bernardino, Filipa; Rentmeister, Kai; Schmidt, Martin J.; Bruehschwein, Andreas; Matiasek, Kaspar; Matiasek, Lara A.; Lauda, Alexander; Schoon, Heinz A.; Fischer, Andrea

    2015-01-01

    Cerebellar malformations can be inherited or caused by insults during cerebellar development. To date, only sporadic cases of cerebellar malformations have been reported in dogs, and the genetic background has remained obscure. Therefore, this study`s objective was to describe the clinical characteristics, imaging features and pedigree data of a familial cerebellar hypoplasia in purebred Eurasier dogs. A uniform cerebellar malformation characterized by consistent absence of the caudal portions of the cerebellar vermis and, to a lesser degree, the caudal portions of the cerebellar hemispheres in association with large retrocerebellar fluid accumulations was recognized in 14 closely related Eurasier dogs. Hydrocephalus was an additional feature in some dogs. All dogs displayed non-progressive ataxia, which had already been noted when the dogs were 5 – 6 weeks old. The severity of the ataxia varied between dogs, from mild truncal sway, subtle dysmetric gait, dysequilibrium and pelvic limb ataxia to severe cerebellar ataxia in puppies and episodic falling or rolling. Follow-up examinations in adult dogs showed improvement of the cerebellar ataxia and a still absent menace response. Epileptic seizures occurred in some dogs. The association of partial vermis agenesis with an enlarged fourth ventricle and an enlarged caudal (posterior) fossa resembled a Dandy-Walker-like malformation in some dogs. Pedigree analyses were consistent with autosomal recessive inheritance. PMID:25668516

  15. Dandy-Walker malformation and Wisconsin syndrome: novel cases add further insight into the genotype-phenotype correlations of 3q23q25 deletions

    PubMed Central

    2013-01-01

    Background The Dandy-Walker malformation (DWM) is one of the commonest congenital cerebellar defects, and can be associated with multiple congenital anomalies and chromosomal syndromes. The occurrence of overlapping 3q deletions including the ZIC1 and ZIC4 genes in few patients, along with data from mouse models, have implicated both genes in the pathogenesis of DWM. Methods and results Using a SNP-array approach, we recently identified three novel patients carrying heterozygous 3q deletions encompassing ZIC1 and ZIC4. Magnetic resonance imaging showed that only two had a typical DWM, while the third did not present any defect of the DWM spectrum. SNP-array analysis in further eleven children diagnosed with DWM failed to identify deletions of ZIC1-ZIC4. The clinical phenotype of the three 3q deleted patients included multiple congenital anomalies and peculiar facial appearance, related to the localization and extension of each deletion. In particular, phenotypes resulted from the variable combination of three recognizable patterns: DWM (with incomplete penetrance); blepharophimosis, ptosis, and epicanthus inversus syndrome; and Wisconsin syndrome (WS), recently mapped to 3q. Conclusions Our data indicate that the 3q deletion is a rare defect associated with DWM, and suggest that the hemizygosity of ZIC1-ZIC4 genes is neither necessary nor sufficient per se to cause this condition. Furthermore, based on a detailed comparison of clinical features and molecular data from 3q deleted patients, we propose clinical diagnostic criteria and refine the critical region for WS. PMID:23679990

  16. COL4A1 Mutations Cause Ocular Dysgenesis, Neuronal Localization Defects, and Myopathy in Mice and Walker-Warburg Syndrome in Humans

    PubMed Central

    Harrington, Emily P.; de Leau, Michelle; Lyons, David; Kabaeva, Zhyldyz; Manzini, M. Chiara; Dobyns, William B.; Walsh, Christopher A.; Michele, Daniel E.; Gould, Douglas B.

    2011-01-01

    Muscle-eye-brain disease (MEB) and Walker Warburg Syndrome (WWS) belong to a spectrum of autosomal recessive diseases characterized by ocular dysgenesis, neuronal migration defects, and congenital muscular dystrophy. Until now, the pathophysiology of MEB/WWS has been attributed to alteration in dystroglycan post-translational modification. Here, we provide evidence that mutations in a gene coding for a major basement membrane protein, collagen IV alpha 1 (COL4A1), are a novel cause of MEB/WWS. Using a combination of histological, molecular, and biochemical approaches, we show that heterozygous Col4a1 mutant mice have ocular dysgenesis, neuronal localization defects, and myopathy characteristic of MEB/WWS. Importantly, we identified putative heterozygous mutations in COL4A1 in two MEB/WWS patients. Both mutations occur within conserved amino acids of the triple-helix-forming domain of the protein, and at least one mutation interferes with secretion of the mutant proteins, resulting instead in intracellular accumulation. Expression and posttranslational modification of dystroglycan is unaltered in Col4a1 mutant mice indicating that COL4A1 mutations represent a distinct pathogenic mechanism underlying MEB/WWS. These findings implicate a novel gene and a novel mechanism in the etiology of MEB/WWS and expand the clinical spectrum of COL4A1-associated disorders. PMID:21625620

  17. Revision of the species of Jaliscoa Bou?ek within a review of the identity, relationships and membership of Jaliscoa, Catolaccus Thomson, Eurydinoteloides Girault, Lyrcus Walker and Trimeromicrus Gahan (Hymenoptera: Pteromalidae).

    PubMed

    Gibson, Gary A P

    2013-01-01

    The limits of Lyrcus Walker (1842), Catolaccus Thomson (1878), Eurydinoteloides Girault (1913a), Trimeromicrus Gahan (1914), and Jaliscoa Bou?ek (1993) are re-evaluated and redefined to better reflect observed distribution of morphological features. Nine of 13 New World species of Catolaccus are transferred to other genera and photographs of the primary type specimens are given to assist future recognition. New features are provided to assist identification of the remaining four Nearctic species of Catolaccus and these are compared to European species, with the observation that C. kansensis (Girault 1917c) could be a junior synonym of C. crassiceps (Masi 1911). Trimeromicrus is removed from synonymy under Lyrcus for the single species T. maculatus Gahan (1914) rev. comb. Newly synonymized under Lyrcus is the Australasian genus Neocylus Bou?ek (1988) n. syn. Ten species are newly transferred to Lyrcus-L. nigraeneus (Girault 1915) n. comb. (from Neocylus), L. helice (Walker 1843) n. comb. and L. cyaneus (Girault 1911) n. comb. (from Catolaccus), and L. albiclavus (Girault 1917c) n. comb., L. capitis (Burks 1955) n. comb., L. chalcis (Burks 1955) n. comb., L. coeliodis (Ashmead 1896) n. comb., L. deuterus (Crawford 1911) n. comb., L. nigroaeneus (Ashmead 1894a)n. comb. and L. rosaecolis (Burks 1955) n. comb. (from Zatropis Crawford 1908). Catolaccus pallipes Ashmead (1894b) is newly transferred to Pteromalus Swederus (1795) as Pteromalus pallipes (Ashmead) n. comb. and Catolaccus fragariae Rohwer (1934) to Lariophagus Crawford (1909) as Lariophagus fragariae (Rohwer) n. comb. Nine species are newly transferred to Eurydinoteloides-E. tepicensis (Ashmead 1895) n. comb. (from Catolaccus), E. dymnus (Walker 1847) n. comb., E. hermeas (Walker 1847) n. comb., E. incerta (Ashmead 1893) n. comb., E. orontas (Walker 1847) n. comb., E. perdubia (Girault 1916) n. comb., E. platensis (De Santis in De Santis et al. 1979) n. comb. and E. timaea (Walker 1847)n. comb. (from Lyrcus), and E. eudubia (Özdikmen 2011) n. comb. (from Spintherus Thomson 1878). Four species are newly transferred to Jaliscoa-J. grandis (Burks 1954) n. comb. and J. hunteri (Crawford 1908) n. comb. (from Catolaccus), and J. townsendi (Crawford 1912) n. comb. and J. vulgaris (Ashmead 1894b) n. comb. (from Pteromalus). The species of Jaliscoa are revised to include J. nudipennis Bou?ek 1993, J. bouceki n. sp., J. hunteri and J. vulgaris. Re-established in synonymy under J. hunteri is J. townsendi n. comb. One new species of Pteromalus, P. grisselli n. sp., is described as an egg predator in the egg sacs of Dictyna coloradensi Chamberlin (Araneae: Dictynidae) and compared to Catolaccus species and other pteromalids that are predators of spider eggs. Lectotypes are designated for Pteromalus helice Walker (1843), Catolaccus pallipes Ashmead (1894b) and Catolaccus vulgaris Ashmead (1894b). Diagnoses are given to differentiate Catolaccus, Eurydinoteloides, Jaliscoa, Lyrcus and Trimeromicrus from each other, and more extensive descriptions given to help differentiate these genera from other Pteromalinae. Morphological features are illustrated through macrophotography and scanning electron photomicrography. PMID:24699811

  18. 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

  19. 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

  20. Evolution of Late Miocene to Contemporary Displacement Transfer Between the Northern Furnace Creek and Southern Fish Lake Valley Fault Zones and the Central Walker Lane, Western Great Basin, Nevada

    NASA Astrophysics Data System (ADS)

    Oldow, J. S.; Geissman, J. W.

    2013-12-01

    Late Miocene to contemporary displacement transfer from the north Furnace Creek (FCF) and southern Fish Lake Valley (FLVF) faults to structures in the central Walker Lane was and continues to be accommodated by a belt of WNW-striking left-oblique fault zones in the northern part of the southern Walker Lane. The WNW fault zones are 2-9 km wide belts of anastomosing fault strands that intersect the NNW-striking FCF and southern FLVF in northern Death Valley and southern Fish Lake Valley, respectively. The WNW fault zones extend east for over 60 km where they merge with a 5-10 km wide belt of N10W striking faults that marks the eastern boundary of the southern Walker Lane. Left-oblique displacement on WNW faults progressively decreases to the east, as motion is successively transferred northeast on NNE-striking faults. NNE faults localize and internally deform extensional basins that each record cumulative net vertical displacements of between 3.0 and 5.2 km. The transcurrent faults and associated basins decrease in age from south to north. In the south, the WNW Sylvania Mountain fault system initiated left-oblique motion after 7 Ma but does not have evidence of contemporary displacement. Farther north, the left-oblique motion on the Palmetto Mountain fault system initiated after 6.0 to 4.0 Ma and has well-developed scarps in Quaternary deposits. Cumulative left-lateral displacement for the Sylvania Mountain fault system is 10-15 km, and is 8-12 km for the Palmetto fault system. The NNE-striking faults that emanate from the left-oblique faults merge with NNW transcurrent faults farther north in the eastern part of the Mina deflection, which links the Owens Valley fault of eastern California to the central Walker Lane. Left-oblique displacement on the Sylvania Mountain and Palmetto Mountain fault zones deformed the Furnace Creek and Fish Lake Valley faults. Left-oblique motion on Sylvania Mountain fault deflected the FCF into the 15 km wide Cucomungo Canyon restraining bend, segmented the >3.0 km deep basin underlying southern Fish Lake Valley, and formed a 2 km wide restraining bend in the FLVF. Part of the left-oblique motion on the Palmetto Mountain fault zone crosses Fish Lake Valley and offsets the FLVF in a 3 km wide restraining bend with the remainder being taken-up by NNW structures along the eastern side of southern Fish Lake Valley.

  1. 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-stepping system of dextral fault. The left steps are analogous to Riedel shears developing above a more through-going shear zone at depth. However, a site directly adjacent to the Benton Springs fault is rotated ~30° CW, likely due to fault drag. These results show the complex and important contribution of vertical-axis rotations in accommodation of dextral shear.

  2. 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-3 fatty acids and the AKGs in the tumor cells’ membranes. Conclusions SLOil is another marine source of lipids with similar FOil anti-cachectic capacity. Furthermore, despite being less potent than FOil, SLOil presented significant in vivo antitumor effects. These results suggest that the chronic supplementation with SLOil may be adjuvant of the anti-cancer therapy. PMID:24131597

  3. 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 fault zone (0.3-0.8 mm/yr) and the eastern sinistral Coaldale fault (0.4 mm/yr) suggest that transfer of dextral slip from the narrow White Mountains fault zone is explained best by a simple shear couple whereby slip is partitioned into three different components: horizontal extension along the Queen Valley fault, dominantly dextral slip along the Coyote Springs fault, and dominantly sinistral slip along the Coaldale fault. A velocity vector diagram illustrating fault slip partitioning predicts contraction rates of <0.1 to 0.5 mm/yr across the Coyote Springs and western Coaldale faults. The predicted long-term contraction across the Mina deflection is consistent with present-day GPS data.

  4. Stimulation of bone resorption results in a selective increase in the growth rate of spontaneously metastatic Walker 256 cancer cells in bone.

    PubMed

    Kostenuik, P J; Singh, G; Suyama, K L; Orr, F W

    1992-11-01

    To test the hypothesis that bone metastasis is related to the rate of bone remodeling, we have examined the effect of enhanced bone resorption on the growth of spontaneously metastatic Walker 256 (W256) cancer cells. Bone resorption was stimulated in male Fischer rats by injecting Rice H-500 Leydig tumor cells subcutaneously. The resorptive response of the skeleton was confirmed in a pilot study by evaluating parameters of bone morphometry after 4, 7 and 10 days of tumor burden. The distal femoral epiphyses had 35 +/- 10% more osteoclast surface, 83 +/- 11% less osteoblast surface, and 46 +/- 5% less trabecular bone after 10 days of tumor burden, compared to non-tumor-bearing controls. To evaluate the effect of Leydig tumor-induced bone resorption on the growth response of W256 cells, 20 rats were injected intramuscularly with 2 x 10(7) W256 cells, and 20 rats were vehicle-injected. Two days later, 10 rats from each group were injected subcutaneously with Leydig tumor cells. Twelve days after W256/vehicle injection, rats were injected with [3H]thymidine, killed 2 h later, and their femurs, liver, lungs and kidneys were processed for histology. In rats injected with Leydig tumor cells only, enhanced bone resorption was confirmed by a 40 +/- 4% increase in serum calcium concentration, a 48 +/- 8% decrease in trabecular bone content, and a 72 +/- 15% decrease in osteoblast surface, compared with non-tumor-bearing rats. Metastatic W256 cells adjacent to trabecular bone in Leydig tumor-bearing rats had a 56 +/- 18% greater relative [3H]thymidine labeling index (TdR) than did W256 cells in the bones of non-Leydig tumor-bearing rats. The TdRs of W256 cells in the liver, lungs, and kidneys were not affected by Leydig tumor burden. In this model, enhanced bone resorption was associated with the selective growth promotion of metastatic W256 cells in bone, suggesting the existence of a bone-derived factor which is mitogenic to W256 cells. PMID:1451351

  5. 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 transition from quadrupedality to bipedality. That is, the activity of the philogenetically youngest supraspinal centers for bipedal walking responsible for suppression of the older supraspinal centers for quadrupedal gait may be interrupted at the atavistic level due to genetic and/or environmental factors. Consequently, it is assumed that these individuals prefer their natural wrist-walking to move around more quickly and efficiently. PMID:17365105

  6. Date Initials WALKER HEALTH CENTER

    E-print Network

    Wenderholm, Elaine

    ? __________________________________________ 10. PH of cardiomyopathy, hypertension, heart murmur, arrhythmia or long QT syndrome)? _____________________________________________________________________________________________________________________________________________________________________________________ 13. FH of Marfan's syndrome or aortic aneurysm? FH of heart disease, hypertension of surviving

  7. Disease Precautions for Dog Walkers

    MedlinePLUS

    ... Room Professional Development Jobs Veterinary Salary Calculator Personal Development Training & Service Opportunities Excellence in Veterinary Medicine Awards Veterinary Education Economics & Practice Economics & Finance Practice Management Client Materials Insurance ...

  8. November 18, 2004 Mark Walker

    E-print Network

    , coal and natural gas provides diversity that spreads risk as compared to placing an undue reliance is primarily attributable to the risk and uncertainty associated with tight supplies of natural gas and dramatic increases in natural gas prices over the last two years. These increases in gas prices

  9. September 29, 2006 Mark Walker

    E-print Network

    Dam proposal based on a BPA/USFS cost share agreement, and are requesting that this funding remain), and Washington Department of Fish and Wildlife #12;(WDFW), submitted for and received BPA funding to improve and school involvement. This blend of research, monitoring, evaluation, on-the-ground restoration

  10. October 6, 2006 Mark Walker

    E-print Network

    to document existing habitat conditions and fish populations within the White Salmon River subbasin term benefit beyond the confines of the White Salmon River basin. This proposal was the top rated an opportunity to comment on the proposed funding recommendation for the White Salmon River Watershed Assessment

  11. October 3, 2006 Mark Walker

    E-print Network

    Funding Review Emerald People's Utility District (Emerald) is pleased to provide comments regarding the Councils F&W Program funding for Fiscal years 2007 ­ 2009. Emerald realizes the importance of preserving of providing low, cost-based power to our customers. Thus, Emerald appreciates the Council's efforts in working

  12. December 12, 2003 Mark Walker

    E-print Network

    to Bonneville's high fixed costs for its debt as exacerbating BPA's vulnerabilities. While debt load does impact% of its total assets in 20021 . While this is a high percentage, it is not unusual for a federal power

  13. INTRODUCTION TheWalkerLanebeltisastructurallyandkinematicallycom-

    E-print Network

    Faulds, James E.

    in the Pacific­North America plate bound- ary zone between the Sierra Nevada Mountains and the Basin and Range of the Sierra Nevada­Great Valley block, which is not parallel to its eastern margin, i.e., the eastern Sierra analysis, in Oldow, J.S., and Cashman, P.H., eds., Late Cenozoic Structure and Evolution of the Great Basin

  14. October 19, 2007 Mark Walker

    E-print Network

    by refusing to sugarcoat the challenge the region faces in achieving the necessary national and regional CO2 of the solutions at our disposal, taking proactive steps to implement those solutions sooner rather than later

  15. October 18, 2007 Mark Walker

    E-print Network

    . Snake River Dams Analysis The PPC believes the Council made a proper decision when it omitted from of the Snake River Dams. In previous drafts it was suggested that the generation lost by removing the Snake that conservation and renewables could fill the void for generation lost by removing the Snake River Dams fails

  16. 15 September 2006 Mark Walker

    E-print Network

    that the Description of the Maturation Study within the project 198605000 White Sturgeon Mitigation and Restoration sturgeon work were not consulted in this analysis, and this project has not yet been completed. The ISRP 198605000 White Sturgeon Mitigation and Restoration in the Columbia and Snake Rivers Upstream from

  17. Edited by Thomas Blumenthal. Last revised July 14, 2006. Published September 5, 2006. This chapter should be cited as: Blackwell, T. K. and Walker, A. K. Transcription mechanisms (September 5, 2006), WormBook, ed. The C. elegans Research Community, WormBo

    E-print Network

    Blackwell, Keith

    . This chapter should be cited as: Blackwell, T. K. and Walker, A. K. Transcription mechanisms (September 5, 2006 Place, Boston, MA 02215, USA Table of Contents 1. mRNA transcription involves conserved mechanisms and the fundamental mechanisms involved in transcription are conserved among eukaryotes, including C. elegans. Recent

  18. Construction and analysis of antennal cDNA library from rice striped stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), and expression profiles of putative odorant-binding protein and chemosensory protein genes.

    PubMed

    Gong, Zhong-Jun; Liu, Su; Jiang, Yan-Dong; Zhou, Wen-Wu; Liang, Qing-Mei; Cheng, Jiaan; Zhang, Chuan-Xi; Zhu, Zeng-Rong; Gurr, Geoff M

    2015-05-01

    In this study, we constructed a high-quality cDNA library from the antennae of the Chilo suppressalis (Walker) (Lepidoptera: Pyralidae). A total of 1,235 colonies with inserts greater than 0.7 kb were sequenced and analyzed. Homology searching coupled with bioinformatics analysis identified 15 and 7 cDNA sequences, respectively, encoding putative odorant-binding proteins (OBPs) and chemosensory proteins (CSPs). A phylogenetic tree of CsupCSPs showed that each CsupCSP has orthologs in Manduca sexta and Bombyx mori with strong bootstrapping support. One CSP was either very specific or more related to the CSPs of another species than to conspecific CSP. The expression profiles of the OBPs and CSPs in different tissues were measured by real-time quantitative PCR. The results revealed that of the 11 OBP genes, the transcript levels of CsupOBP1, CsupOBP5, and CsupOBP7 were higher in both male and female antennae than those in other tissues. And CsupCSP7 was highly expressed in both male and female antennae. Based on these results, the possible physiological functions of CsupOBPs and CsupCSPs were discussed. PMID:25639603

  19. November 19, 2004 Mr. Mark Walker

    E-print Network

    in the four Northwestern states. Our members are a unique combination of environmental and consumer organizations, as well as businesses and manufacturers that develop renewable energy equipment and projects

  20. Genetics Home Reference: Walker-Warburg syndrome

    MedlinePLUS

    ... the Genetics Home Reference Glossary . See also Understanding Medical Terminology . References (4 links) The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a ...

  1. (12) United States Patent Walker et ai.

    E-print Network

    Shamos, Michael I.

    International, Jan. 20, 1996, Feature Section at p. 1I. "Risk-based Repricing Draws Flak", Credit Card Manage to Work", May 1992, v. 13, 15, pp. 57+.* Intelligent Enterprise, "E-Business Makeover", Dec. 7, 1999, pp of parameters selected by the customer. 14 Claims, 7 Drawing Sheets I BANK CENTRAL CONTROLLER EOf NEWPRIC

  2. October 18, 2007 Mr. Mark Walker

    E-print Network

    , the federal hydropower system is part of a multi-purpose system that includes other authorized purposes not only affect hydropower production, as you have shown, but would also eliminate navigation. U.S. Army to ten times the energy of barging, with commensurate comparisons for emissions. We believe

  3. Common Runners/Walkers Foot Injuries

    ERIC Educational Resources Information Center

    McDaniel, Larry W.; Ihlers, Matt; Haar, Calin; Jackson, Allen; Gaudet, Laura

    2010-01-01

    This is my 35th year of running most days a year. That was correct most days a year not a week. Running is my first priority each day. Developing a routine will assist those who want exercise to become a habit. After I awake I drink a glass of water and a cup of coffee then my dog "Jazz" and I hit the streets for a 3-4 mile run. Later in…

  4. Empirical Studies in Discourse Marilyn A. Walker

    E-print Network

    Moore, Johanna D.

    ; and improvements in component technologies and tools for building and testing discourse and dialogue testbeds or programs that interpret or generate them. ¢ AT&T Labs Research, 600 Mountain Ave. 2D-441, Murray Hill, NJ environmental factors which are features of the task that are fixed from the system designer's viewpoint, system

  5. by John Walker The Hacker's Diet

    E-print Network

    Bernstein, Daniel

    month 118 Every year 124 #12; CONTENTS iii 8 PLANNING MEALS 127 Why plan meals? 127 Calorie targets 128 trend 201 Calculating weight loss rate 203 Calculating calorie deficit 203 Making weight charts 203 Volume 212 Abbreviations 213 The Weight of Water 213 13 CALORIES IN VARIOUS FOODS 215 ABOUT THE AUTHOR

  6. VICIOUS WALKERS, FRIENDLY WALKERS AND YOUNG TABLEAUX II: WITH A WALL

    E-print Network

    Krattenthaler, Christian

    Abstract.We derive new results for the number of star and watermelon conf* *igu- rations of vicious and watermelons both in the abs* *ence of a wall and in the presence of a wall number of watermelon configurations was conjectured. Later, in [21] it was sho* *wn how certain

  7. Media Inquiries: Department of Communications Michael Walker, 212-769-5766; walker@amnh.org

    E-print Network

    Walter, M.Todd

    @amnh.org www.amnh.org June 2012 AMERICAN MUSEUM OF NATURAL HISTORY ANNOUNCES 2012 YOUNG NATURALIST AWARDS of the world around them, said Ellen V. Futter, President of the American Museum of Natural History. We? These are some of the questions that 13 student scientists explored through the American Museum of Natural

  8. Walker Branch WatershedWalker Branch Watershed LongLong--term hydrology, streamterm hydrology, stream

    E-print Network

    Post, Wilfred M.

    budgetsbudgets Stream metabolismStream metabolism and nutrient cyclingand nutrient cycling Algae, bryophytes,Algae, bryophytes, and effects of light,and effects of light, nutrients andnutrients and herbivoryherbivory Organic

  9. ROBERT M. WALKER February 6, 1929-February 12, 2004

    E-print Network

    Price, P. Buford

    was a visionary with two great dreams, both of which paid off handsomely. He conjectured that meteorites and lunar. During the depression, when there were few jobs, the three of them moved to a farm near Cobleskill, New during the depression was challenging. He had to walk a mile, sometimes in blizzard conditions, to catch

  10. Visualising Risk for Hill Walkers Alastair Jardine, William Mackaness

    E-print Network

    in a route selection task that shows that the visualisation of risk information does indeed affect the decision making associated with a number of hill walking activities (namely route planning and execution maps and drawing upon our experiences ­ in the UK, for example via Ordnance Survey's 1:25 000 scale OS

  11. October 11, 2006 Mr. Mark Walker, Director of Public Affairs

    E-print Network

    -supported and locally- recommended projects during this funding cycle and, (3) reduce the project funding request and capitalizing three projects (Walla Walla Juvenile and Adult Passage Improvements, Gardena Farms Irrigation projects as well as adding the Council-required three-step planning process for the proposed Walla Walla

  12. Cosmological Principle & The Robertson-Walker Metric September 13, 2007

    E-print Network

    Weijgaert, Rien van de

    & infinite · Universe does not have a boundary and no center · Dynamics: action at a distance instantaneous surprise, his equations implied the Universe to be unstable, either it should expand or collapse Cosmology Gravity is ruling the Universe. It was Newton who was the first to establish this. Following

  13. Supporting Information: A Synthetic DNA Walker for Molecular Transport

    E-print Network

    Pierce, Niles A.

    , FAM, Texas Red) to double the distance between dyes with adjacent fluorescence spectra. These concerns and the resulting oligomers were used without further purification. DNA stock solutions (40-60 µM) were prepared. Fluorescence signals from four dif- ferent dyes were collected during the same run using the multi-dye mode

  14. Two World Walkers: The Eagles in Aerospace Program.

    ERIC Educational Resources Information Center

    Stark, Jason

    1997-01-01

    The Nez Perce council, NASA, and the University of Idaho initiated a program that enables Native American students to identify and correspond with Native American professionals in aeronautical careers who are willing to mentor these students. The goal is to move academia and academic programs into the realm of Native American identity, ideology,…

  15. Artificial tribotactic microscopic walkers: walking based on friction gradients.

    PubMed

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

    2014-10-24

    Friction, the resistive force between two surfaces sliding past each other, is at the core of a wide diversity of locomotion schemes. While such schemes are well described for homogeneous environments, locomotion based on friction in inhomogeneous environments has not received much attention. Here we introduce and demonstrate the concept of tribotaxis, a motion that is guided by gradients in the friction coefficient. Our system is composed of microwalkers that undergo an effective frictional interaction with biological receptors on the substrate, which is regulated by the density of such receptors. When actuated stochastically, microwalkers migrate to regions of higher friction, much like a chemotactic cell migrates to regions of higher chemoattractant concentration. Simulations and theory based on biased random walks are in excellent agreement with experiments. We foresee important implications for tribotaxis in artificial and natural locomotion in biological environments. PMID:25379939

  16. A Robotic Walker That Provides Guidance Aaron Morris

    E-print Network

    Thrun, Sebastian

    for the elderly, and devices that provide mobility assistance are criti- cal for the health and well being with navigation and global orientation. Our system provides these features in addition to the stability localization and navi- gation combined with a shared-control haptic interface. The system has been tested

  17. 75 FR 38833 - Walker River Basin Acquisition Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-06

    ..., 2007 (72 FR 54456). Public scoping meetings on the EIS were held in October 2007 and meetings on the... Availability of the Draft EIS on July 24, 2009 (74 FR 36737) and a notice to reopen the comment period for review of the Draft EIS on September 23, 2009 (74 FR 48596). In 2008, DOI promulgated its regulations...

  18. Assessment of the Web using Genetic Programming Reginald L. Walker

    E-print Network

    Fernandez, Thomas

    for each search engine using sassafras tea" as the basis. Excite AltaVista NetCenter HotBot Infoseek LookSmart Yahoo! sassafras tea" 336 91 0 126 337 73 + sassafras tea" +herb 66 21 0 5 66 0 sassafras tea" NEAR herb 143311 - - - - - - 143311 - - sassafras tea" OR herb 555226 - - - - - - 555226 - - sassafras tea

  19. A hexapod walker using a heterarchical architecture for action selection

    PubMed Central

    Schilling, Malte; Paskarbeit, Jan; Hoinville, Thierry; Hüffmeier, Arne; Schneider, Axel; Schmitz, Josef; Cruse, Holk

    2013-01-01

    Moving in a cluttered environment with a six-legged walking machine that has additional body actuators, therefore controlling 22 DoFs, is not a trivial task. Already simple forward walking on a flat plane requires the system to select between different internal states. The orchestration of these states depends on walking velocity and on external disturbances. Such disturbances occur continuously, for example due to irregular up-and-down movements of the body or slipping of the legs, even on flat surfaces, in particular when negotiating tight curves. The number of possible states is further increased when the system is allowed to walk backward or when front legs are used as grippers and cannot contribute to walking. Further states are necessary for expansion that allow for navigation. Here we demonstrate a solution for the selection and sequencing of different (attractor) states required to control different behaviors as are forward walking at different speeds, backward walking, as well as negotiation of tight curves. This selection is made by a recurrent neural network (RNN) of motivation units, controlling a bank of decentralized memory elements in combination with the feedback through the environment. The underlying heterarchical architecture of the network allows to select various combinations of these elements. This modular approach representing an example of neural reuse of a limited number of procedures allows for adaptation to different internal and external conditions. A way is sketched as to how this approach may be expanded to form a cognitive system being able to plan ahead. This architecture is characterized by different types of modules being arranged in layers and columns, but the complete network can also be considered as a holistic system showing emergent properties which cannot be attributed to a specific module. PMID:24062682

  20. Effective trapping of random walkers in complex networks

    NASA Astrophysics Data System (ADS)

    Hwang, S.; Lee, D.-S.; Kahng, B.

    2012-04-01

    Exploring the World Wide Web has become one of the key issues in information science, specifically in view of its application to the PageRank-like algorithms used in search engines. The random walk approach has been employed to study such a problem. The probability of return to the origin (RTO) of random walks is inversely related to how information can be accessed during random surfing. We find analytically that the RTO probability for a given starting node shows a crossover from a slow to a fast decay behavior with time and the crossover time increases with the degree of the starting node. We remark that the RTO probability becomes almost constant in the early-time regime as the degree exponent approaches two. This result indicates that a random surfer can be effectively trapped at the hub and supports the necessity of the random jump strategy empirically used in the Google's search engine.

  1. Molecular Devices A Unidirectional DNA Walker That Moves

    E-print Network

    Yin, Peng

    Yan,* Xiaoju G. Daniell, Andrew J. Turberfield,* and John H. Reif* A major challenge in nanotechnology is to precisely transport a nanoscale object from one location on a nanostructure to another location along a platform for embedded DNA nanomechan- ical devices to perform the desired transportation. A diverse group

  2. Systematics of the Copitarsia Incommoda (Walker) pest complex (Lepidoptera: Noctuidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phylogenetic relationships of four pest species in the noctuid genus Copitarsia were investigated using adult morphology and mitochondrial DNA (COI). Separate analyses of morphological and COI data provide the same topology of relationships. Adult morphology provides useful characters for separating...

  3. 75 FR 38833 - Walker River Basin Acquisition Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-06

    ...Program as authorized in Public Laws 109-103 and 111-85 is not...decrease has resulted in extremely poor water quality and deteriorated...As a result, several Federal laws have been passed to address the...as authorized in two of those laws, Public Laws 109-103 and...

  4. Iain S. Walker1 and Max H. Sherman1

    E-print Network

    and Construction Sealants and Adhesives, ASTM STP 1453, A. Wolf Ed., American Society for Testing and Materials by LBNL is being used as a basis for an ASTM Standard under sub-committee E6.41. LBNL tests found provides technical background for preparing an ASTM test method for duct sealant durability, test data

  5. How I do Knowledge Transfer Prof Peter Walker

    E-print Network

    Burton, Geoffrey R.

    , both intellectually and in other ways." IMPACT "The impact of our research and development will be more, providing air-tightness, and using low energy- consumption devices and renewable energy sources. However Materials, with Peter at the head, has a well-established interest in low-carbon and renewable insulation

  6. Coupled uncertainty provided by a multifractal random walker

    NASA Astrophysics Data System (ADS)

    Koohi Lai, Z.; Vasheghani Farahani, S.; Movahed, S. M. S.; Jafari, G. R.

    2015-10-01

    The aim here is to study the concept of pairing multifractality between time series possessing non-Gaussian distributions. The increasing number of rare events creates "criticality". We show how the pairing between two series is affected by rare events, which we call "coupled criticality". A method is proposed for studying the coupled criticality born out of the interaction between two series, using the bivariate multifractal random walk (BiMRW). This method allows studying dependence of the coupled criticality on the criticality of each individual system. This approach is applied to data sets of gold and oil markets, and inflation and unemployment.

  7. Dynamics of Robertson-Walker spacetimes with diffusion

    E-print Network

    Artur Alho; Simone Calogero; Maria P. Machado Ramos; Ana J. Soares

    2015-02-09

    We study the dynamics of spatially homogeneous and isotropic spacetimes containing a fluid undergoing microscopic velocity diffusion in a cosmological scalar field. After deriving a few exact solutions of the equations, we continue by analyzing the qualitative behavior of general solutions. To this purpose we recast the equations in the form of a two dimensional dynamical system and perform a global analysis of the flow. Among the admissible behaviors, we find solutions that are asymptotically de-Sitter both in the past and future time direction and which undergo accelerated expansion at all times.

  8. A Space Station robot walker and its shared control software

    NASA Technical Reports Server (NTRS)

    Xu, Yangsheng; Brown, Ben; Aoki, Shigeru; Yoshida, Tetsuji

    1994-01-01

    In this paper, we first briefly overview the update of the self-mobile space manipulator (SMSM) configuration and testbed. The new robot is capable of projecting cameras anywhere interior or exterior of the Space Station Freedom (SSF), and will be an ideal tool for inspecting connectors, structures, and other facilities on SSF. Experiments have been performed under two gravity compensation systems and a full-scale model of a segment of SSF. This paper presents a real-time shared control architecture that enables the robot to coordinate autonomous locomotion and teleoperation input for reliable walking on SSF. Autonomous locomotion can be executed based on a CAD model and off-line trajectory planning, or can be guided by a vision system with neural network identification. Teleoperation control can be specified by a real-time graphical interface and a free-flying hand controller. SMSM will be a valuable assistant for astronauts in inspection and other EVA missions.

  9. Taxonomic Study of the Genus Apalacris Walker (Orthoptera: Catantopidae).

    PubMed

    Zheng, Z M; Lin, L L; Niu, Y

    2016-02-01

    The research history of the genus Apalacris is reviewed; a key to all known species of the genus is given, and one new species, Apalacris eminifronta n. sp., and one new combination, Apalacris maculifemura (Lin & Zheng), are described. The new species is very closely related to Apalacris antennata Liang, but differs in the following characters: (1) tegmen longer, reaching apex of hind femur; (2) basal part of inner side of hind femur orange red; (3) frontal ridge more protruded, obviously depressed under median ocellus in lateral view; and (4) epiphallus bridge prominent, ancora shorter than anterior projection. PMID:26514365

  10. The Logical Approach to Stack Typing Amal Ahmed David Walker

    E-print Network

    Ahmed, Amal

    -carrying code system, a low-level program is accompanied by a proof that the program will not perform some "bad they would like to use for their own purposes, but also al- lows them to donate idle computational resources

  11. The Primitive Topology of a Scheme Mark E. Walker

    E-print Network

    for a stimulating series of lectures at Northwestern University in the Winter of 1997 which sparked some of the ideas contained in this paper. The author also thanks Kevin Knudson, Chuck Weibel, and Roger Wiegand

  12. The Primitive Topology of a Scheme Mark E. Walker #

    E-print Network

    for a stimulating series of lectures at Northwestern University in the Winter of 1997 which sparked some of the ideas contained in this paper. The author also thanks Kevin Knudson, Chuck Weibel, and Roger Wiegand

  13. The Primitive Topology of a Scheme Mark E. Walker *

    E-print Network

    in the Winter of 1997 which sparked some of the ideas contained in this paper. The author also thanks Kevin Knudson, Chuck Weibel, and Roger Wiegand for useful discussions related to the contents of this paper

  14. Guidelines for Residential Commissioning Craig Wray, Iain Walker, Max Sherman

    E-print Network

    Road, Berkeley, CA 94720 is a national laboratory of the U.S. Department of Energy managed .......................................................................................................................................... 2 STRUCTURE

  15. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... by reference listed in this section in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. You may... Conshohocken, PA 19428-2959 USA, telephone: 610-832-9585; http://www.astm.org/. You may inspect copies at...

  16. The evolution of carotenoid coloration in estrildid finches: a biochemical analysis

    E-print Network

    McGraw, Kevin J.

    and other colorful tissues in seven species of estrildids. Star finches (Neochmia ruficauda) and diamond the blood and liver and used both to acquire a yellow plumage color. However, five other estrildids (common carotenoids along with two metabolites (dehydrolutein and anhydrolutein) through the blood and/or liver

  17. Canada thistle biological control agents on two South Dakota wildlife refuges

    USGS Publications Warehouse

    Reed, C.C.; Larson, D.L.; Larson, J.L.

    2006-01-01

    We monitored populations of Canada thistle biocontrol agents Cassida rubiginosa, Ceutorhynchus litura, Larinus (= Hadroplantus) planus, Urophora cardui, Orellia (= Terellia) ruficauda, and Rhinocyllus conicus on Canada thistle (Cirsium arvense) at two national wildlife refuges in South Dakota from 1999 through 2003. C. litura, U. cardui, O. ruficauda, and R. conicus were present on both refuges. Agent populations were low except for C. litura, which was present in up to 90% of stems in some plots. C. litura infestation did not reduce thistle flowering, stem length, or over-winter survival. There was no change in thistle stem numbers over the study period and no difference in stem numbers in areas of high C. litura populations compared to areas of low C. litura populations. Our results suggest that insect biological control agents are inadequate for reduction of Canada thistle in southern South Dakota.

  18. Walker and Pei Zhou D'Souza, Su Wang, Yaohua Xue, Graham C.

    E-print Network

    Zhou, Pei

    Click here http://www.jbc.org/content/287/31/26400.full.html#ref-list-1 This article cites 48 references, 17 drug resistance after chemotherapy. The eukaryotic Y-family poly- merase Rev1 is an essential over the shallow 1- 2 surface and creates a deep hydrophobic cavity to interact with the essential FF

  19. The dual-task methodology and assessing the attentional demands of ambulation with walkers 

    E-print Network

    Cowley, Tammara Kemp

    1994-01-01

    of the walking tasks in conjunction with the RT task, which constituted the dual-task condition. The second study replicated the above design using six patients with low back/lower extremity pain that increased with weight bearing. The final study involved 12...

  20. Model task for the dynamics of an underwater two-legged walker

    NASA Technical Reports Server (NTRS)

    Beletskiy, V. V.; Golubkov, V. V.; Stepanova, Y. A.

    1979-01-01

    A model task of two-legged underwater walking was examined. Characteristics of the walking were established. The underwater walking device is a substantial sphere, which moves on dual-member legs. The dynamics of the device were investigated with the calculation of the buoyancy of Archimedes, and the force of hydrodynamic resistance.

  1. Forest nutrient and carbon pools at Walker Branch Watershed: Changes during a 21-year period

    SciTech Connect

    Trettin, C.C.; Johnson, D.W.; Todd, D.E. Jr.

    1999-10-01

    A 21-yr perspective on changes in nutrient and C pools on undisturbed upland forest sites is provided. Plots originally representing four cover types have been sampled three times. On each plot, forest biomass, forest floor, and soil, to a depth of 60 cm, were measured, sampled, and analyzed for Ca, Mg, C, N, and P. Exchangeable soil Ca and Mg have declined in most soils. Despite the low exchangeable Ca, cumulative sequestration in the biomass has exceeded the soil pool, suggesting that soil supplies below 60 cm are satisfying the biomass demand. Extractable soil P also declined, with means ranging from 4.2 to 18.2 kg ha{sup {minus}1}, as a result of reductions in the mineral soil and Oi horizon. The loss of extractable soil P exceeded biomass sequestration in all but one plot, suggesting abiotic soil processes as the removal mechanism. Soil C and N were either stable, although highly variable, or declined, which was unexpected in these undisturbed sites. The net C balance of these sites was controlled by aboveground sequestration, which offset changes in the soil and forest floor. Soil parent material and geomorphic setting strongly influenced the changes in soil properties during the 21-yr period, reflecting the importance of those factors in assessing soil nutrient and C cycles over that of forest cover type. The variability encountered in the periodic soil measurements highlights the difficulty in detecting temporal changes in soil chemical properties.

  2. Experimental in vivo measurements of light emission in plants: a perspective dedicated to David Walker

    E-print Network

    Govindjee

    , Botanicheskaya Street 35, Moscow 127276, Russia e-mail: suleyman.allakhverdiev@gmail.com S. I. Allakhverdiev Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia (Potchefstroom Campus), Potchefstroom 2520, Republic of South Africa Govindjee (&) Department of Biochemistry

  3. Random walker with improved weighting function for interactive medical image segmentation.

    PubMed

    Yin, Lim Khai; Rajeswari, Mandava

    2014-01-01

    To segment an image using the random walks algorithm; users are often required to initialize the approximate locations of the objects and background in the image. Due to its segmenting model that is mainly reflected by the relationship among the neighborhood pixels and its boundary conditions, random walks algorithm has made itself sensitive to the inputs of the seeds. Instead of considering the relationship between the neighborhood pixels solely, an attempt has been made to modify the weighting function that accounts for the intensity changes between the neighborhood nodes. Local affiliation within the defined neighborhood region of the two nodes is taken into consideration by incorporating an extra penalty term into the weighting function. Besides that, to better segment images, particularly medical images with texture features, GLCM variance is incorporated into the weighting function through kernel density estimation (KDE). The probability density of each pixel belonging to the initialized seeds is estimated and integrated into the weighting function. To test the performance of the proposed weighting model, several medical images that mainly made up of 174-brain tumor images are experimented. These experiments establish that the proposed method produces better segmentation results than the original random walks. PMID:25227043

  4. Variability in Stepping Direction Explains the Veering Behavior of Blind Walkers

    PubMed Central

    Kallie, Christopher S.; Schrater, Paul R.; Legge, Gordon E.

    2008-01-01

    Walking without vision results in veering, an inability to maintain a straight path that has important consequences for blind pedestrians. We addressed whether the source of veering in the absence of visual and auditory feedback is better attributed to errors in perceptual encoding or undetected motor error. Three experiments had the following results: no significant differences in the shapes of veering trajectories were found between blind and blindfolded participants; accuracy in detecting curved walking paths was not correlated with simple measures of veering behavior; and explicit perceptual cues to initial walking direction did not reduce veering. We present a model that accounts for the major characteristics of our participants' veering behavior by postulating three independent sources of undetected motor error: initial orientation, consistent biases in step direction, and most importantly variable error in individual steps. PMID:17311487

  5. Surfactant effect on persistence of oxadiazolyl 3(2H)-pyridazinones against Pseudaletia separata walker.

    PubMed

    Huang, Qingchun; Wu, Jihua; Kong, Yuping; Liu, Manhui; Cao, Song

    2007-01-01

    The photodynamic decomposition of two new insect-growth inhibitors (IGRs), 2-tert-butyl-5-[5'-aryl-2'-(1',3',4'-oxadiazolyl)methoxy]-3(2H)-pyridazinones (OPB) and its 4-chloro substituted derivative (OPC), and effect of surfactants on persistence of their bioactivity were taken into investigation. Both chemicals were significantly induced to photolysis by ultraviolet light at 365 nm wavelength and their inhibitory activities against Pseudaletia separata larvae decreased with the increasing irradiation time. However, irradiation at 254 nm wavelength didn't cause their photodegradation. Triton X-100 and Succinic-sulfonie acidic sodium but not Tween 60 possessed strong capability to slow down the decomposition and obviously prolonged the half life of OPC in laboratory and field whilst effects of the three surfactants almost did not preserve the inhibitory activity of OPB. Data suggested that electron-withdrawing halogen (-Cl) on the pi electron system in planar benzene-oxadialyl structures might reduce the efficiency of OPC on ultraviolet (UV) photoabsorption, and its hydrophobic interaction with the surfactants might be beneficial for forming stable micellar solubilization, thus sustaining the chemical's bioactivity. PMID:17454384

  6. Improved Rehabilitation Walker Miguel Alvarez, Jason Porter, Richard Rubel; Advisor: Dr. Donald Bloswick

    E-print Network

    van den Berg, Jur

    attachment sections which made assembly easier. Directional locking wheels were jack is self locking due to a bevel gear system inside. The original handle was replaced with a hand wheel which offers ergonomic benefits to the user

  7. Convection, cloud-radiative feedbacks and thermodynamic ocean coupling in simple models of the Walker circulation

    NASA Astrophysics Data System (ADS)

    Sobel, Adam H.; Bretherton, Christopher S.; Gildor, Hezi; Peters, Matthew E.

    The authors consider a set of simple models for the divergent component of the tropical atmospheric circulation, and the associated precipitation field. A number of strong simplifying assumptions are made, leaving deep convection and radiation (both simply parameterized) as the key processes in the models. The first case considered is that of fixed sea surface temperature (SST), with an SST gradient imposed across the domain, in the limit of zero convective time scale or strict quasi-equilibrium (SQE). Steady solutions are found for sufficiently weak cloud-radiative feedback. As the parameter controlling the strength of the cloud-radiative feedback is increased, the region of nonzero precipitation shrinks in size and the precipitation grows stronger there. For cloud-radiative feedback stronger than a particular value, steady solutions cannot be found, and numerically obtained time-dependent solutions blow up. In the next case considered, the slab ocean lower boundary condition is used. In this case the behavior is dramatically different. In the steady solutions, the strength of the radiative feedback now has little effect on the size of the precipitating region. The finite convective time scale changes the stability criterion, and when the steady solutions become unstable, rather than blowing up, well-behaved radiative-convective oscillations set in. The mechanism for these oscillations is essentially local radiative-convective or surface flux convective instability, so they can be studied at a single point. Their frequencies are intraseasonal, and some inferences can be drawn from them about how ocean coupling affects the Madden-Julian oscillation. The simplicity of the models allows a relatively complete understanding of their behavior. The sensitivity of the solutions to the key parameters, especially the convective time scale and the cloud radiative feedback parameter, are discussed in some detail.

  8. Stack-Based Typed Assembly Language Greg Morrisett Karl Crary David Walker Neal Glew

    E-print Network

    TAL. TAL is su ciently expressive to serve as a target language for compilers of high-level languages on stack allocation. This paper presents STAL, an extension of TAL with stack constructs and stack types assembly language TAL and proved that its type system was sound with respect to an operational semantics

  9. StackBased Typed Assembly Language # Greg Morrisett, Karl Crary, Neal Glew, and David Walker

    E-print Network

    Glew, Neal

    Cornell University Abstract. In previous work, we presented a Typed Assembly Language (TAL). TAL is su, an extension of TAL with stack constructs and stack types to support the stack allocation style. We show. In Morrisett et al. [23], we presented a typed assembly language (TAL) and proved that its type system

  10. StackBased Typed Assembly Language Greg Morrisett Karl Crary David Walker Neal Glew

    E-print Network

    (TAL). TAL is sufficiently expressive to serve as a target language for compilers of high on stack allocation. This paper presents STAL, an extension of TAL with stack constructs and stack types assembly language (TAL) and proved that its type system was sound with respect to an operational semantics

  11. From System F to Typed Assembly Language* Greg Morrisett David Walker Karl Crary Neal Glew

    E-print Network

    Glew, Neal

    of a statically typedCassemblyompiling a source language* * to a statically typed in- language (TAL) and present to TAL. The TAL we presentcisonventional untyped compiler. * *An optimizing com- based]. Furt* *hermore, the ability Our translation to TAL is specified as a sequencetofo type

  12. Stack-Based Typed Assembly Language ? Greg Morrisett, Karl Crary, Neal Glew, and David Walker

    E-print Network

    Glew, Neal

    presented a Typed Assembly Language (TAL). TAL is sufficiently expressive to serve as a target language, an extension of TAL with stack constructs and stack types to support the stack allocation style. We show. In Morrisett et al. [23], we presented a typed assembly language (TAL) and proved that its type system

  13. Stack-Based Typed Assembly Language Greg Morrisett, Karl Crary, Neal Glew, and David Walker

    E-print Network

    Glew, Neal

    University Abstract. In previous work, we presented a Typed Assembly Language (TAL). TAL is sufficiently, an extension of TAL with stack constructs and stack types to support the stack allocation style. We show. In Morrisett et al. [23], we presented a typed assembly language (TAL) and proved that its type system

  14. Journeying as Religious Education: The Shaman, the Hero, the Pilgrim, and the Labyrinth Walker

    ERIC Educational Resources Information Center

    Senn, Corelyn F.

    2002-01-01

    In this article the author looks at the image of journey and its archeform, quest, and finds two spiritual concepts: that of movement to the center followed by a return, and the concomitant understanding that all that has arisen and reached maturity must return to renew itself. Four journeys, the shamanic journey of soul, the hero's journey of…

  15. Tenebrio molitor antifreeze protein gene identification and regulation Wensheng Qin, Virginia K. Walker

    E-print Network

    Qin, Wensheng

    Tenebrio molitor antifreeze protein gene identification and regulation Wensheng Qin, Virginia K into the construct, similar to the enhancement of transgenic expression seen in several other systems. The addition rights reserved. Keywords: Gene family; Hormone regulation; Intron; Promoter identification; Response

  16. Interacting quantum walkers: two-body bosonic and fermionic bound states

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    We investigate the dynamics of bound states of two interacting particles, either bosons or fermions, performing a continuous-time quantum walk on a one-dimensional lattice. We consider the situation where the distance between both particles has a hard bound, and the richer situation where the particles are bound by a smooth confining potential. The main emphasis is on the velocity characterizing the ballistic spreading of these bound states, and on the structure of the asymptotic distribution profile of their center-of-mass coordinate. The latter profile generically exhibits many internal fronts.

  17. Mechanical Hip Actuation Of A 2-D Passive-Dynamics Based Walker

    E-print Network

    Ruina, Andy L.

    , the robot thus created has no innate predisposition to walking; if we were to pick it up mid-stride and put `07 William Seidel `07 Human Power, Biomechanics, and Robotics Laboratory Department of Theoretical bipedal robot. Perhaps most intuitive way of imitating how humans move might be described as brute

  18. , 20130047, published 2 June 20143722014Phil. Trans. R. Soc. A Walker Smith

    E-print Network

    Stevens, David

    , ocean glider, water mass, climate model, iron fertilization Author for correspondence: Karen J. Heywood in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from

  19. Octad Orbits for certain Subgroups of M 24. Peter Rowley and Louise Walker

    E-print Network

    Higham, Nicholas J.

    with the largest simple Fischer group. 1 Introduction and Notation Since its discovery in the second half of the nineteenth century by Emil Mathieu [4],[5], M24, the Mathieu group of degree 24, has been much studied. Being geometry (Fi 24 being the largest Fischer simple group). Now, the residue of a point in 1 #12;this geometry

  20. Local inhomogeneities in a Robertson-Walker background. II. Flux conditions at boundary surfaces

    SciTech Connect

    Lake, K.

    1980-12-15

    Energy flux doncitions imposed on spherical boundary surfaces are examined. The zero flux restriction which is the hallmark of the standard ''Swiss cheese'' type construction, is relaxed. We discuss a class of locally inhomogeneous exact solutions to the Einstein equations which admit an effectively Newtonian accretion mode.