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Sample records for versigonalia ruficauda walker

  1. Host gut microorganisms' cues mediate orientation behaviour in the larva of the parasitoid Mallophora ruficauda.

    PubMed

    Groba, H F; Castelo, M K

    2016-02-01

    The robber fly Mallophora ruficauda is one of the most important apicultural pests in the Pampas region of Argentina. This species is a parasitoid of scarab beetle larvae. Females lay eggs away from the host, and the larvae perform active search behaviour toward Cyclocephala signaticollis third instar larvae, parasitoid's preferred host. This behaviour is mediated by host-related chemical cues produced in hosts' fermentation chamber. Also, C. signaticollis larvae are attracted to fermentation chamber extracts. As scarab larvae have microbe-rich fermentation chamber, it has been suggested that microorganisms could be involved in the production of these semiochemicals. The aims of this work were first to ascertain the presence of microorganisms in the fermentation chamber of C. signaticollis larvae and second to determine the role of microorganisms in the orientation response of parasitoid and host larvae. We found that microorganisms-free C. signaticollis larvae showed deterioration in their development and did not produce the attractive semiochemicals. Therefore, we isolated fermentation chamber microorganisms of host larvae by means of different cultures media, and then, assayed different microorganisms' stimuli by binary choice tests. We were able to isolate microorganisms and determine that M. ruficauda larvae are attracted to semiochemicals from protein degradation in the fermentation chamber. However, C. signaticollis larvae were not attracted to any semiochemicals associated with microorganisms' activity in the fermentation chamber. Although we were unable to elucidate the exact role of gut microorganisms in host behaviour, we discuss their relevance in parasitoid host-seeking behaviour and host conspecific interaction in M. ruficauda-C. signaticollis system. PMID:26521818

  2. Incidence of Non-Immunological Defenses of Soil White Grubs on Parasitism Success of Mallophora ruficauda Larva (Diptera: Asilidae)

    PubMed Central

    Castelo, Marcela K.; Crespo, José E.

    2012-01-01

    White grubs are larvae of Coleoptera of the family Scarabaeidae. They are known because of their intensive feeding habits on crop roots. Mallophora ruficauda (Diptera: Asilidae) is a dipteran parasitoid whose larva is a natural enemy for white grubs. This species is a solitary ectoparasitoid, where both female and larva realize different steps in the host location process. Female place its eggs in high grasslands and then, the larva finds and parasitizes the host in the ground. There are nine potential hosts in the area of action of this parasitoid; however a high preference for Cyclocephala signaticollis has been observed (87% of field parasitism). It is known that many insects have developed defensive and immunological mechanisms when attacked by a parasitoid, which can be behavioral, physiological, chemical or genetic. The objectives of this work were to investigate what kind of defense and non-immunological associated mechanisms the white grubs have against this parasitoid and to understand why M. ruficauda have such a high preference for masked chafer grubs or Cyclocephala species. In particular, for each white grub species, we asked: (1) If there is a differential behavioral reaction when a parasitoid attack is simulated; (2) If body attributes of white grubs species have influence on defense behavior, and particularly for the masked chafer C. signaticollis; and (3) Why this species is the most selected by M. ruficauda. It was found that behavioral defenses of white grubs would explain the parasitism pattern of M. ruficauda larvae and its preference for C. signaticollis. PMID:26466623

  3. The Rusty-tailed Flycatcher (Muscicapa ruficauda; Aves: Muscicapidae) is a member of the genus Ficedula.

    PubMed

    Hooper, Daniel M; Olsson, Urban; Alström, Per

    2016-09-01

    The phylogenetic relationships of the avian family Muscicapidae (Old World chats and flycatchers) have historically been enigmatic and remain an active area of study. Widespread instances of non-monophyly resulting from misleading morphological and behavioral similarities have merited numerous taxonomic revisions to the group. Here we report one such instance with regard to the Rusty-tailed Flycatcher Muscicapa ruficauda, which has recently been placed in the newly proposed monotypic genus Ripleyia, due to inferred sister relationship to the genus Muscicapa and related genera (Voelker et al., 2016a). This name was later replaced by Ripleyornis, as it was realized that Ripleyia is a junior homonym of a genus of Mollusca (Voelker et al., 2016b). Using a Bayesian phylogenetic assessment of the Muscicapidae with near-complete taxon sampling of the genus Ficedula for five loci, along with an acoustic comparison of M. ruficauda to a subset of other flycatcher species, we show that this species should be reassigned to the genus Ficedula and accordingly that the names Ripleyia and Ripleyornis are both junior synonyms of Ficedula. PMID:27246102

  4. 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.

  5. Incidence of Non-Immunological Defenses of Soil White Grubs on Parasitism Success of Mallophora ruficauda Larva (Diptera: Asilidae).

    PubMed

    Castelo, Marcela K; Crespo, José E

    2012-01-01

    White grubs are larvae of Coleoptera of the family Scarabaeidae. They are known because of their intensive feeding habits on crop roots. Mallophora ruficauda (Diptera: Asilidae) is a dipteran parasitoid whose larva is a natural enemy for white grubs. This species is a solitary ectoparasitoid, where both female and larva realize different steps in the host location process. Female place its eggs in high grasslands and then, the larva finds and parasitizes the host in the ground. There are nine potential hosts in the area of action of this parasitoid; however a high preference for Cyclocephala signaticollis has been observed (87% of field parasitism). It is known that many insects have developed defensive and immunological mechanisms when attacked by a parasitoid, which can be behavioral, physiological, chemical or genetic. The objectives of this work were to investigate what kind of defense and non-immunological associated mechanisms the white grubs have against this parasitoid and to understand why M. ruficauda have such a high preference for masked chafer grubs or Cyclocephala species. In particular, for each white grub species, we asked: (1) If there is a differential behavioral reaction when a parasitoid attack is simulated; (2) If body attributes of white grubs species have influence on defense behavior, and particularly for the masked chafer C. signaticollis; and (3) Why this species is the most selected by M. ruficauda. It was found that behavioral defenses of white grubs would explain the parasitism pattern of M. ruficauda larvae and its preference for C. signaticollis. PMID:26466623

  6. 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.

  7. Walker's Eleodes (Coleoptera: Tenebrionidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The type specimens of five species of Eleodes described by Francis Walker were studied in order to establish their true identity. The synonymy of Eleodes convexicollis Walker and Eleodes conjunctus Walker with E. obscurus (Say); that of Eleodes latiusculus Walker with E. humeralis LeConte; and that ...

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

    PubMed

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

    2014-01-01

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

  9. Using a walker

    MedlinePlus

    ... you can transport it easily. Your surgeon or physical therapist will help you choose the type of walker ... try to use stairs and escalators unless a physical therapist has trained you how to use them with ...

  10. 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.

  11. 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 ξ(n), where n labels different bouncy walkers, are drawn from a distribution ϱ(ξ(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 ϱ(ξ(n)) is heavy-tailed, ϱ(ξ(n))≃ξ(n) (-1-α) (0<α<1) for large ξ(n), we identify a new universality class in which density relaxations, characterized by the dynamic structure factor S(Q, t), follows a Mittag-Leffler relaxation, and the mean square displacement (MSD) of a tracer particle grows as t(δ) with time t, where δ = α∕(1 + α). If instead ϱ is light-tailed such that the mean friction constant exist, S(Q, t) decays exponentially and the MSD scales as t(1/2). We also derive tracer particle force response relations. All results are corroborated by simulations and explained in a simplified model. PMID:21280802

  12. 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

  13. 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.

  14. 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.

  15. Genetics Home Reference: Dandy-Walker malformation

    MedlinePlus

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

  16. Genetics Home Reference: Walker-Warburg syndrome

    MedlinePlus

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

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

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

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

  18. Adjustable Walker for the Handicapped

    NASA Technical Reports Server (NTRS)

    Kitts, R. G.

    1984-01-01

    Front legs adjust at touch of lever for use on stairs or ramps. Spring loaded legs extend when lever is depressed by user. Legs lock in position when lever is released. Lever mounted on either side of walker or on both sides, so legs operated independently.

  19. Walker Branch Watershed Ecosystems Data

    DOE Data Explorer

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

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

    PubMed Central

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

    1997-01-01

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

  1. George Walker, 1926-2005

    NASA Astrophysics Data System (ADS)

    Self, Stephen

    2006-08-01

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

  2. Averaging Robertson-Walker cosmologies

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

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

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

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

  4. 1. CONTEXTUAL VIEW OF WALKER BRIDGE WITH APPROACHES, OVERLOOKING HIGHWAY ...

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

    1. CONTEXTUAL VIEW OF WALKER BRIDGE WITH APPROACHES, OVERLOOKING HIGHWAY 96 (IN FOREGROUND); FACING SOUTHEAST. - Walker Bridge, Spanning Klamath River and connecting Highway 96 and Walker Road, Klamath River, Siskiyou County, CA

  5. 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....

  6. 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....

  7. 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....

  8. 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....

  9. 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....

  10. 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.

  11. 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

  12. 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.

  13. Boltzmann active walkers and rough surfaces

    NASA Astrophysics Data System (ADS)

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

    1993-06-01

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

  14. 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

  15. Walker of Time [and Teacher's Guide].

    ERIC Educational Resources Information Center

    Vick, Helen Hughes

    Intended for adolescent readers, this award-winning book is the first in a time travel trilogy that blends ancient Sinagua and present-day Hopi Indian life with archaeology, social awareness, and adventure. The books relate the story of Walker Talayesva, a contemporary Hopi teenager who travels back in time 800 years to take his place as the…

  16. Walker River Paiutes: A Tribal History.

    ERIC Educational Resources Information Center

    Johnson, Edward C.

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

  17. 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…

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

    ERIC Educational Resources Information Center

    Olson, Ted

    1995-01-01

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

  19. 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.

  20. Walker circulation in a transient climate

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  1. 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

  2. Modern lacustrine stromatolites, Walker Lake, Nevada

    NASA Astrophysics Data System (ADS)

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

    1982-05-01

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

  3. Vibrotactile Guidance for Wayfinding of Blind Walkers.

    PubMed

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

    2015-01-01

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

  4. Active walker models: tracks and landscapes

    NASA Astrophysics Data System (ADS)

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

    1992-12-01

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

  5. Time walkers and spatial dynamics of aging information.

    PubMed

    Lizana, L; Rosvall, M; Sneppen, K

    2010-01-29

    The distribution of information is essential for a living system's ability to coordinate and adapt. Random walkers are often used to model this distribution process and, in doing so, one effectively assumes that information maintains its relevance over time. But the value of information in social and biological systems often decays and must continuously be updated. To capture the spatial dynamics of aging information, we introduce time walkers. A time walker moves like a random walker, but interacts with traces left by other walkers, some representing older information, some newer. The traces form a navigable information landscape which we visualize as a river network. We quantify the dynamical properties of time walkers, and the quality of the information left behind, on a two-dimensional lattice. We show that searching in this landscape is superior to random searching. PMID:20366697

  6. Prevention strategies for infant walker-related injuries.

    PubMed Central

    Trinkoff, A; Parks, P L

    1993-01-01

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

  7. DNA Walker-Regulated Cancer Cell Growth Inhibition.

    PubMed

    Li, Feiran; Cha, Tae-Gon; Pan, Jing; Ozcelikkale, Altug; Han, Bumsoo; Choi, Jong Hyun

    2016-06-16

    We demonstrate a DNAzyme-based walker system as a controlled oligonucleotide drug AS1411 release platform for breast cancer treatment. In this system, AS1411 strands are released from fuel strands as a walker moves along its carbon nanotube track. The release rate and amount of anticancer oligonucleotides are controlled by the walker operation. With a walker system embedded within the collagen extracellular matrix, we show that this drug release system can be used for in situ cancer cell growth inhibition. PMID:27059426

  8. Obituary: Robert Mowbray Walker, 1929-2004

    NASA Astrophysics Data System (ADS)

    Schoenherr, Neil T.

    2004-12-01

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

  9. Walker Ranch 3D seismic images

    DOE Data Explorer

    Robert J. Mellors

    2016-03-01

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

  10. 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.

  11. AmeriFlux US-WBW Walker Branch Watershed

    SciTech Connect

    Meyers, Tilden

    2016-01-01

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

  12. 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

  13. 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

  14. 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.

  15. Modeling walker synchronization on the Millennium Bridge.

    PubMed

    Eckhardt, Bruno; Ott, Edward; Strogatz, Steven H; Abrams, Daniel M; McRobie, Allan

    2007-02-01

    On its opening day the London Millennium footbridge experienced unexpected large amplitude wobbling subsequent to the migration of pedestrians onto the bridge. Modeling the stepping of the pedestrians on the bridge as phase oscillators, we obtain a model for the combined dynamics of people and the bridge that is analytically tractable. It provides predictions for the phase dynamics of individual walkers and for the critical number of people for the onset of oscillations. Numerical simulations and analytical estimates reproduce the linear relation between pedestrian force and bridge velocity as observed in experiments. They allow prediction of the amplitude of bridge motion, the rate of relaxation to the synchronized state and the magnitude of the fluctuations due to a finite number of people. PMID:17358316

  16. Modeling walker synchronization on the Millennium Bridge

    NASA Astrophysics Data System (ADS)

    Eckhardt, Bruno; Ott, Edward; Strogatz, Steven H.; Abrams, Daniel M.; McRobie, Allan

    2007-02-01

    On its opening day the London Millennium footbridge experienced unexpected large amplitude wobbling subsequent to the migration of pedestrians onto the bridge. Modeling the stepping of the pedestrians on the bridge as phase oscillators, we obtain a model for the combined dynamics of people and the bridge that is analytically tractable. It provides predictions for the phase dynamics of individual walkers and for the critical number of people for the onset of oscillations. Numerical simulations and analytical estimates reproduce the linear relation between pedestrian force and bridge velocity as observed in experiments. They allow prediction of the amplitude of bridge motion, the rate of relaxation to the synchronized state and the magnitude of the fluctuations due to a finite number of people.

  17. David Alan Walker (1928-2012).

    PubMed

    Edwards, Gerald E; Heber, Ulrich

    2012-06-01

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

  18. Intelligent control of a smart walker and its performance evaluation.

    PubMed

    Grondin, Simon L; Li, Qingguo

    2013-06-01

    Recent technological advances have allowed the development of force-dependent, intelligently controlled smart walkers that are able to provide users with enhanced mobility, support and gait assistance. The purpose of this study was to develop an intelligent rule-based controller for a smart walker to achieve a smooth interaction between the user and the walker. This study developed a rule-based mapping between the interaction force, measured by a load cell attached to the walker handle, and the acceleration of the walker. Ten young, healthy subjects were used to evaluate the performance of the proposed controller compared to a well-known admittance-based control system. There were no significant differences between the two control systems concerning their user experience, velocity profiles or average cost of transportation. However, the admittance-based control system required a 1.2N lower average interaction force to maintain the 1m/s target speed (p = 0.002). Metabolic data also indicated that smart walker-assisted gait could considerably reduce the metabolic demand of walking with a four-legged walker. PMID:24187165

  19. Dandy-Walker Malformation Presenting with Psychological Manifestations.

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    1988-09-01

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

  1. Dandy-Walker Malformation Presenting with Psychological Manifestations

    PubMed Central

    Dahanayake, Dulangi Maneksha Amerasinghe

    2016-01-01

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

  2. 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

  3. 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

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

    NASA Video Gallery

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

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

    PubMed

    Maggi, Silviane; Faulhaber, Gustavo Adolpho Moreira

    2015-01-01

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

  6. 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.

  7. Perturbations of the Robertson-Walker space

    NASA Astrophysics Data System (ADS)

    Hwang, Jai Chan

    This dissertation contains three parts consisting of thirteen chapters. Each chapter is self-contained, and can be read independently. In chapter 1, we have presented a complete set of cosmological perturbation equations using the covariant equations. We also present an explicit solution for the evolution of large scale cosmological density perturbations assuming a perfect fluid. In chapter 2, two independent gauge-invariant variables are derived which are continuous at any transition where there is a discontinuous change in pressure. In chapter 3, we present a Newtonian counterpart to the general relativistic covariant approach to cosmological perturbations. In chapter 4, we present a simple way of deriving cosmological perturbation equations in generalized gravity theories which accounts for metric perturbations in gauge-invariant way. We apply this approach to the f(phi,R)-omega(phi)phi, cphi;c Lagrangian. In chapter 5, we have derived second order differential equations for cosmological perturbations in a Robertson-Walker space, for each of the following gravity theories: f(R) gravity, generalized scalar-tensor gravity, gravity with non-minimally coupled scalar field, and induced gravity. Asymptotic solutions are derived for the large and small scale limits. In chapter 6, classical evolution of density perturbations in the large scale limit is clarified in the generalized gravity theories. In chapter 7, we apply our method to a theory with the Lagrangian L approximately f(R) + gamma RR;c;c. In chapter 8, T(M)ab;b equals 0 is shown in a general ground. In chapter 9, the origin of the Friedmann-like behavior of the perturbed model in the large scale limit is clarified in a comoving gauge. Thus, when the imperfect fluid contributions are negligible, the large scale perturbations in a nearly flat background evolve like separate Friedmann models. In chapter 10, we generalize the perturbation equations applicable to a class of generalized gravity theories with multi

  8. 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

  9. 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

  10. Kinematic and electromyographic patterns of Olympic race walkers.

    PubMed

    Murray, M P; Guten, G N; Mollinger, L A; Gardner, G M

    1983-01-01

    The performance of two Olympic race walkers was studied during free-speed, fast, and race walking. Measurements of the stride and temporal components of gait, as well as the simultaneous displacement patterns of the body segments, and the electromyographic activity of muscles of the trunk and upper and lower limbs were recorded during the three walking speeds. During the testing, the race walkers achieved an average speed of 12.5 km/hr as compared to the 8.7 km/hr average speed achieved by normal men of the same age during fast walking. Race walking was characterized by an increase in cadence and stride length beyond that of normal controls (in a prior study) during fast walking, with stride lengths averaging 125% of stature during race walking, and 115% during normal fast walking. In the two race walkers the amplitudes of most of the movement patterns of the trunk and upper and lower limbs were exaggerated during race walking as compared to normal controls' fast walking. Several mechanisms were used by the race walkers to minimize the vertical excursion of the center of gravity of the body during race walking. All of the muscles monitored in the race walkers showed an increase in the amplitude of electromyographic activity during race walking as compared to fast walking; duration of muscle activity was also usually increased during race walking. Several suggestions for prevention of injuries associated with race walking are made. PMID:6846684

  11. Multiple Walkers in the Wang-Landau Algorithm

    SciTech Connect

    Brown, G

    2005-12-28

    The mean cost for converging an estimated density of states using the Wang-Landau algorithm is measured for the Ising and Heisenberg models. The cost increases in a power-law fashion with the number of spins, with an exponent near 3 for one-dimensional models, and closer to 2.4 for two-dimensional models. The effect of multiple, simultaneous walkers on the cost is also measured. For the one-dimensional Ising model the cost can increase with the number of walkers for large systems. For both the Ising and Heisenberg models in two-dimensions, no adverse impact on the cost is observed. Thus multiple walkers is a strategy that should scale well in a parallel computing environment for many models of magnetic materials.

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

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

    NASA Technical Reports Server (NTRS)

    1958-01-01

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

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

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

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

  15. 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.

  16. Walkers' Navigational Needs?Steam or the Chip?

    NASA Astrophysics Data System (ADS)

    Tippett, Julian

    Surveys reveal that walking is by far the most popular leisure activity in the UK, and still growing. Each year some half a billion specifically involve walking in the countryside and over 60 percent of the adult population claim to participate in walking as a . These statistics serve to confirm our own experience that enormous numbers of walkers go out to enjoy the countryside, but when we say we include Sunday afternoon strollers in Windsor Great Park, a rambling group following the coastal path in Dorset, strong fit youths doing the Pennine Way, or Munro baggers in the Scottish highlands. Walkers come in many a hue.

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

    NASA Astrophysics Data System (ADS)

    Fernández-Jambrina, L.

    2016-08-01

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

  18. 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...

  19. A stochastic DNA walker that traverses a microparticle surface

    PubMed Central

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

    2015-01-01

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

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

    ERIC Educational Resources Information Center

    SHW Group, Inc., Dallas, TX.

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

  1. 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…

  2. 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)

  3. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  5. 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…

  6. 75 FR 51178 - Safety Standard for Infant Walkers; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-19

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

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

    PubMed

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

    2015-02-01

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

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

    PubMed

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Fernández-Jambrina, L.

    2016-03-01

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

  10. 75 FR 35265 - Safety Standard for Infant Walkers: Final Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... walkers in the Federal Register on September 3, 2009. 74 FR 45704. The standard is substantially the same... rule (74 FR at 45705), the stair fall protection provisions in the ASTM standard dramatically affected... change velocities in the step test. Response: As discussed in the preamble to the proposed rule (74 FR...

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

    ERIC Educational Resources Information Center

    Hoffman, Carl

    1993-01-01

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

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

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

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

  13. 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.

  14. A stochastic DNA walker that traverses a microparticle surface

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

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

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

  16. 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…

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

    ERIC Educational Resources Information Center

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

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

  18. Historical adjustments by Walker River to lake-level fall over a tectonically tilted half-graben floor, Walker Lake Basin, Nevada

    NASA Astrophysics Data System (ADS)

    Blair, Terence C.; McPherson, John G.

    1994-08-01

    Historical records of lake and river adjustments in the tectonically active, north—south elongated, Walker Lake extensional basin of west-central Nevada provide important insight to the style and rate that rivers react to tectonic tilt in half grabens. The northern part of this basin, historically containing Walker Lake, is now occupied by the south-flowing Walker River. Walker Lake, presently restricted to the central basin sector, is a perennial water body 30 m deep sustained by, and forming the terminus of, Walker River. Both the river and lake have a strongly asymmetric distribution, located preferentially near the active Walker Lake fault bounding the western basin margin. Walker Lake has withdrawn from the northern basin sector since 1882 due to a 45 m drop in lake level caused by human diversion of the river upstream. This withdrawal has forced Walker River to incrementally lengthen, and to sequentially reposition its delta along the retreating northern lake margin. Twelve deltas have been deposited since 1882 in response to these changes. The initiation of eight of the twelve post-1882 deltas was associated with channel avulsion, and four with channel lengthening. Ten of the twelve channel and delta relocation events entailed significant westward lateral movements toward the Walker Lake fault, illustrating the dominating influence of the basin-floor tectonic tilt on river adjustments. The two eastward shifts were triggered intrinsically by avulsions resulting from erosion of the outer bank of channel meanders. The three phases of progressive westward shifting of the river towards the Walker Lake fault occurred over periods of 18, 6, and 16 years, respectively, documenting the rapid response time of Walker River to basin-floor tectonic tilt despite the countering effects of the intrinsic avulsions, and hindrances to lateral migration caused by the muddy substrate of the former lake bottom deposits within which the river is incised.

  19. 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.

  20. 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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Cook, Kerry H.; Vizy, Edward K.

    2016-08-01

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

  3. Motion-Reversal Transitions in Self-Assembled Colloidal Walkers

    NASA Astrophysics Data System (ADS)

    Moran, Stephanie; Sing, Charles; Alexander-Katz, Alfredo

    2011-03-01

    Nature has created a variety of designs in order to move fluids and transport objects within living organisms. At microscopic scales (in the region of micrometers) two motifs are common: flagella and cilia. Within the cell, however, molecular motors with nanometer dimensions transport small sized vesicles. Here, we describe a novel approach that combines properties from two systems: cilia and molecular motors, to create self-assembled colloidal walkers. These walkers are assembled by superparamagnetic beads in the presence of a rotating homogeneous magnetic field, and are able move in a given direction due to the presence of surfaces which provide an effective friction. The motion is somewhat reminiscent of a person doing cartwheels on ice, where the friction is not high enough to avoid slip, but overall one can attain directed motion in one direction. Interestingly, the motion of the center of mass of these walkers is a non-monotonic function along one cycle of revolution. By exploiting this non-monotonicity, we show that motion reversal is possible in this systems if one carefully controls the friction properties of the surface as well as the confining ``gravitational'' field that maintains the beads near the surface. Our results our important in understanding the motion of micron scale organisms and may be useful in the development of virtual microfluidic platforms.

  4. 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.

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

    USGS Publications Warehouse

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

    2014-01-01

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

  6. Neotectonics and Structural Development of the Northern Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, S. G.; Pierce, I. K. D.; Angster, S.; Carlson, C. W.; Louie, J. N.; Faulds, J. E.; Malawsky, E.

    2015-12-01

    The Walker Lane is a major element of the San Andreas fault system and by itself one of the most accessible and well-known intraplate shear zones in the world. This northwest trending zone of discontinuous active faults and disrupted topography that sits between the Sierra Nevada on the west and the north-northeast trending faults and ranges of the Great Basin to the east is associated with a geodetically well-defined zone of northwest-directed right-lateral shear ranging from ~ 5 to 10 mm/yr. It is the northern section of the Walker lane that includes the Lake Tahoe, Carson, Smith, Mason, Antelope, Bridgeport and Walker Lake basins and Carson and Wabuska structural lineaments that is currently the focus of our investigation. Here, right-lateral shear strain of at least 20-30 km has resulted in the development of this set of roughly en echelon normal fault basins in the absence of any major northwest-directed strike-slip faults. Synthesis of available geologic and geodetic data also shows that geodetic deformation is outpacing the late Quaternary slip rate on active faults across the region. The observations may be explained as the result of inadequate geologic fault slip rate data, by the accommodation of slip by vertical-axis block rotations, or some measure of both. The research presented here describes our initial efforts and findings resulting from collection and analysis of Lidar for evidence of strike-slip along the major structures of the region, the application of cosmogenic, optically stimulated luminescence (OSL) and radiocarbon dating to identified offset surfaces to better quantify the rate at which faults are slipping in the region, and the collection of gravity and paleomagnetic observations to clarify both the current and long-term structural development of the basins and intervening fault blocks.

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

    NASA Astrophysics Data System (ADS)

    Chen, Bang-Yen; Van der Veken, Joeri

    2007-07-01

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

  8. Noncommutative corrections to the Robertson-Walker metric

    SciTech Connect

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

    2008-09-15

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

  9. 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.

  10. Pilot Joe Walker with the X-1E

    NASA Technical Reports Server (NTRS)

    1958-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed

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

    2015-08-01

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

  13. Quantum centipedes: collective dynamics of interacting quantum walkers

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

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

    PubMed

    Hanley, Brian; Bissas, Athanassios

    2016-01-01

    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

  15. 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.

  16. Monocoque structure for the SKITTER three-legged walker

    NASA Astrophysics Data System (ADS)

    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.

    1988-06-01

    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.

  17. Number of distinct sites visited by N random walkers

    NASA Astrophysics Data System (ADS)

    Larralde, Hernan; Trunfio, Paul; Havlin, Shlomo; Stanley, H. Eugene; Weiss, George H.

    1992-05-01

    We study the number of distinct sites visited by N random walkers after t steps SN(t) under the condition that all the walkers are initially at the origin. We derive asymptotic expressions for the mean number of distinct sites in one, two, and three dimensions. We find that passes through several growth regimes; at short times ~td (regime I), for tx<~(t ln[N S1(t)/td/2])d/2 (regime II), and for t>>tx', ~NS1(t) (regime III). The crossover times are tx~ln N for all dimensions, and tx'~∞, exp N, and N2 for one, two, and three dimensions, respectively. We show that in regimes II and III satisfies a scaling relation of the form ~td/2f(x), with x≡N/td/2. We also obtain asymptotic results for the complete probability distribution of SN(t) for the one-dimensional case in the limit of large N and t.

  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

  19. 78 FR 37706 - Safety Standards for Infant Walkers and Infant Swings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ... for Infant Walkers, with 22 modifications to make the standard more stringent. 75 FR 35266. ASTM... assessment bodies for testing infant walkers (75 FR 35282 (June 21, 2010)) and infant swings (78 FR 15836..., with two modifications to make the standard more stringent. 77 FR 66703. ASTM notified CPSC that...

  20. 78 FR 25234 - Proposed Establishment of Class E Airspace; Walker, MN

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-30

    ...This action proposes to establish Class E airspace at Walker, MN. Controlled airspace is necessary to accommodate new Standard Instrument Approach Procedures (SIAP) at Walker Municipal Airport. The FAA is taking this action to enhance the safety and management of Instrument Flight Rules (IFR) operations for SIAPs at the...

  1. 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…

  2. GeoFrame Walker Lane: Overview, Rationale, and Objectives

    NASA Astrophysics Data System (ADS)

    Stockli, D. F.

    2006-12-01

    GeoFrame is an integrative geologic initiative that takes a multi-dimensional view of the building and modification of the North American continent by systematic integration of geologic and geochronometric investigations and the results from unprecedented geophysical imaging as part of the Earthscope Program. The GeoFrame effort envisions these focus site investigations to entail map-scale arrays of passive source seismic receivers and associated active source seismic studies and complementary geophysics in conjunction with geologic-based synthesis and targeted studies. One of these focus sites is the Walker Lane region in eastern California and western Nevada, situated between the Basin and Range province and the unextended Sierra Nevada block. This GeoFrame focus site workshop is particularly timely given the deployment schedule of the USArray "BigFoot" array. The Walker Lane intraplate deformation zone accommodates nearly ~25% of present-day relative motion between the Pacific and North American plates and might represent an incipient plate boundary. It provides a world-class example of the present modification of continental lithosphere by the process of transcurrent faulting and rifting and offers the opportunity to seamlessly integrate surface geology, structural geology, petrology, geo- and thermochronology, and the history of the continental lithosphere with ongoing processes in the Earth's mantle. It affords opportunities to address a number of questions posed within Earthscope such as: mechanisms of strain transfer, the role of lithospheric rheology in strain localization and seismic response, the nature and timescales of transient fault behavior, and the role of magmas and fluids in deforming lithosphere. Implicit in the design and implementation of Earthscope is the recognition that progress on issues such as these requires an integrative geophysical and geological investigation of the Walker Lane. As such, it will open new avenues of collaboration and

  3. Profiling core-periphery network structure by random walkers

    PubMed Central

    Rossa, Fabio Della; Dercole, Fabio; Piccardi, Carlo

    2013-01-01

    Disclosing the main features of the structure of a network is crucial to understand a number of static and dynamic properties, such as robustness to failures, spreading dynamics, or collective behaviours. Among the possible characterizations, the core-periphery paradigm models the network as the union of a dense core with a sparsely connected periphery, highlighting the role of each node on the basis of its topological position. Here we show that the core-periphery structure can effectively be profiled by elaborating the behaviour of a random walker. A curve—the core-periphery profile—and a numerical indicator are derived, providing a global topological portrait. Simultaneously, a coreness value is attributed to each node, qualifying its position and role. The application to social, technological, economical, and biological networks reveals the power of this technique in disclosing the overall network structure and the peculiar role of some specific nodes. PMID:23507984

  4. Walker-Warburg Syndrome: A Case with multiple uncommon features

    PubMed Central

    Bedri, Hibba A.; Mustafa, Babiker M.; Jadallah, Yosif M.

    2011-01-01

    Walker-Warburg syndrome (WWS) is a rare and lethal autosomal recessive disorder, caused by defective glycosylation of α-dystroglycan that is important for muscle integrity and neuronal migration. Mutations in six genes involved in the glycosylation of α-dystroglycan (POMT1, POMT2, POMGNT1, FCMD, FKRP and LARGE) have been identified in WWS patients, and others remain under study. Prenatal diagnosis may be possible by means of prenatal ultrasonography, or magnetic resonance imaging. We report a patient demonstrating the typical clinical features of lissencephaly, congenital muscular dystrophy and ocular abnormalities, in addition to other features including hydrocephalus, occipital encephalocele, agenesis of the corpus collosum, microphthalmia, ventricular septal defect, and rocker bottom feet deformity.

  5. Null hypersurfaces in generalized Robertson-Walker spacetimes

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  6. The heel-contact gait pattern of habitual toe walkers.

    PubMed

    Crenna, P; Fedrizzi, E; Andreucci, E; Frigo, C; Bono, R

    2005-04-01

    We used kinematic, kinetic and EMG analysis to compare the spontaneous heel-contact gait patterns of 13 children classified as habitual toe walkers (HTWs) and age-matched controls. In the HTWs, the incidence of spontaneous heel-contact strides during a single recording session ranged from 15% to 92%, with no correlation with age, passive ankle joint excursion, walking speed and trial order. Hallmarks of the heel-contact strides were premature heel-rise, reversal of the second rocker, relative shortening of the loading response and anticipation and enhancement of the electromyographic (EMG) activity normally observed in the triceps surae (TS) during the first half of the stance phase. This variant of the locomotor program is different from the walking patterns observed in normally developing toddlers and children with cerebral palsy (CP). It does not necessarily reflect a functional adaptation to changes in the rheological properties of the muscle-tendon complex. PMID:15760747

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. Response of the Walker Circulation to LGM Forcing: Implications for Detection in Proxies

    NASA Astrophysics Data System (ADS)

    di Nezio, P. N.; Clement, A. C.; Vecchi, G. A.; Broccoli, A. J.; Otto-Bliesner, B. L.

    2010-12-01

    The response of the Walker circulation to Last Glacial Maximum (LGM) climate forcing is analysed using an ensemble of 6 coordinated coupled climate models. Unlike global warming experiments, in which all six models simulate a robust weakening of the Walker circulation, the models do not agree in the response to LGM forcing. Two opposing mechanisms operating over the ascending branch of the Walker circulation in the LGM experiments could explain the inter-model differences. The Walker circulation strengthens due to a constrain imposed by changes in the hydrological cycle, consistent with the mechanism proposed to explain the response to global warming. However, the Walker circulation is also weakened by a reduction in convection over the Maritime Continent due to increased land surface resulting from a lowered sea level. Even those models that simulate a stronger Walker circulation do not simulate a clear La Nina-like ocean cooling opposite to the robust El Nino-like warming simulated in the global warming experiments. Instead, the changes in the Walker circulation have a robust and unambiguous signature on the tilt of the equatorial thermocline as expected from momentum balance. The models also indicate that due to competing dynamical and thermodynamical effects the changes in the thermocline do not agree with the changes in the depth of the 18C isotherm. The changes in the Walker circulation have a clear signature on the precipitation changes, but these changes fail to translate into a clear signature in surface salinity. These results indicate that real LGM changes in the Walker circulation can only be detected by proxies of thermocline depth.

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  11. 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.

  12. 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

  13. ISS Update: Astronaut Shannon Walker – 07.17.2012

    NASA Video Gallery

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

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

    ERIC Educational Resources Information Center

    Fontenot, Chester J.

    1977-01-01

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

  15. 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.

  16. Revision of the Afrotropical species of Norbanus Walker (Hymenoptera: Pteromalidae).

    PubMed

    Mitroiu, Mircea-Dan

    2015-01-01

    The Afrotropical species of Norbanus Walker, 1843 (Hymenoptera: Pteromalidae) are revised. Four previously described Afrotropical species are recognized as valid and redescribed: N. africanus Subba Rao, 1973, N. garouae (Risbec, 1956) comb. nov. (transferred from Bruchobius Ashmead), N. kitegaensis (Risbec, 1957) and N. seyrigi (Risbec, 1952) comb. nov. (from Habrocytus Thomson). In addition, the Mediterranean species N. tenuicornis Bouček, 1970 is recorded for the first time from the Afrotropical region, and 21 species are described as new: N. aequus sp. nov., N. awi sp. nov., N. brevicephalus sp. nov., N. breviclava sp. nov., N. caloramans sp. nov., N. draco sp. nov., N. erebus sp. nov., N. foritempus sp. nov., N. gibber sp. nov., N. gracilis sp. nov., N. incombo sp. nov., N. ingens sp. nov., N. longissimus sp. nov., N. maliarphae sp. nov., N. mustatai sp. nov., N. pilosus sp. nov., N. pleuralis sp. nov., N. polaszeki sp. nov., N. prinslooi sp. nov., N. rotundus sp. nov., and N. sunabron sp. nov. Three extralimital species from North Africa are included in the key: N. cerasiops (Masi, 1922), N. guyoni (Giraud, 1869), and N. obscurus (Masi, 1922). Lectotypes are designated for N. cerasiops, N. kitegaensis and N. seyrigi. The subgenus Picroscytoides Masi is placed in synonymy with Norbanus s.s. syn. nov. Host records are given for several new species, including some economically important pests of maize, sorghum or rice. PMID:26249477

  17. 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.

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Nanxiang; Hao, Qi

    2008-04-01

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

  1. 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.

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

    PubMed

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

    2015-01-01

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

  3. 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.

  4. A jump persistent turning walker to model zebrafish locomotion

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  6. Long term gait outcomes of surgically treated idiopathic toe walkers.

    PubMed

    McMulkin, Mark L; Gordon, Andi B; Tompkins, Bryan J; Caskey, Paul M; Baird, Glen O

    2016-02-01

    Toe walking is a common gait deviation which in the absence of a known cause is termed idiopathic toe walking. Surgical treatment in the presence of a triceps surae contracture includes tendo-Achilles or gastrocnemius/soleus recession and has been shown to be effective in improving kinematic outcomes at a one year follow up. The purpose of this study was to assess longer term kinematic and kinetic outcomes of children with idiopathic toe walking treated surgically for gastrocnemius/soleus contractures. Eight subjects with a diagnosis of idiopathic toe walking who had surgical lengthening of the gastrocnemius/soleus and had previous motion analysis laboratory studies pre-operative and 1 year post-operative, returned for a motion analysis laboratory study greater than 5 years since surgery. Subjects completed lower extremity physical exam and 3-D computerized kinematics and kinetics. Significant improvements for mean pelvic tilt, peak dorsiflexion in stance and swing, and overall kinematics index at 1 year post-operative were maintained at 5 years post-operative. Kinetic variables of ankle moment and power were improved at 1 year and 5 years post-operative. On physical exam, dorsiflexion with knee extended was tighter from 1 to 5 year follow-up which did not correspond to the functional changes of gait. Idiopathic toe walkers who were treated surgically for triceps surae contractures showed significant improvements in key kinematic and kinetic gait analysis variables at 1 year post-operative that were maintained at 5 years post-operative. Overall, subjects were satisfied with outcomes of the surgery, unrestricted in activities, and reported minimal pain. PMID:27004661

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

    PubMed

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

    2014-03-01

    Stimuli responsive polyelectrolyte hydrogels may be useful for soft robotics because of their ability to transform chemical energy into mechanical motion without the use of external mechanical input. Composed of soft and biocompatible materials, gel robots can easily bend and fold, interface and manipulate biological components and transport cargo in aqueous solutions. Electrical fields in aqueous solutions offer repeatable and controllable stimuli, which induce actuation by the re-distribution of ions in the system. Electrical fields applied to polyelectrolyte-doped gels submerged in ionic solution distribute the mobile ions asymmetrically to create osmotic pressure differences that swell and deform the gels. The sign of the fixed charges on the polyelectrolyte network determines the direction of bending, which we harness to control the motion of the gel legs in opposing directions as a response to electrical fields. We present and analyze a walking gel actuator comprised of cationic and anionic gel legs made of copolymer networks of acrylamide (AAm)/sodium acrylate (NaAc) and acrylamide/quaternized dimethylaminoethyl methacrylate (DMAEMA Q), respectively. The anionic and cationic legs were attached by electric field-promoted polyion complexation. We characterize the electro-actuated response of the sodium acrylate hydrogel as a function of charge density and external salt concentration. We demonstrate that "osmotically passive" fixed charges play an important role in controlling the bending magnitude of the gel networks. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices and robots in aqueous solutions. PMID:24651405

  8. 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

  9. 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.

  10. 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

  11. 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

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

    PubMed

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

    2016-01-01

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

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

    USGS Publications Warehouse

    Pavelko, Michael T.; Orozco, Erin L.

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    PubMed

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

    2016-06-16

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

  16. Removable cast walker boots yield greater forefoot off-loading than total contact casts

    PubMed Central

    Gutekunst, David J.; Hastings, Mary K.; Bohnert, Kathryn L.; Strube, Michael J.; Sinacore, David R.

    2011-01-01

    Background Elevated plantar loading has been implicated in the etiology of plantar ulceration in individuals with diabetes mellitus and peripheral neuropathy. Total contact casts and cast walker boots are common off-loading strategies to facilitate ulcer healing and prevent re-ulceration. The purpose of this study was to compare off-loading capabilities of these strategies with respect to plantar loading during barefoot walking. Methods Twenty-three individuals with diabetes, peripheral neuropathy, and plantar ulceration were randomly assigned to total contact cast (N=11) or removable cast walker boot (N=12). Each subject underwent plantar loading assessment walking barefoot and wearing the off-loading device. Analysis of covariance was used to compare loading patterns in the off-loading devices for the whole foot, hindfoot, midfoot, and forefoot while accounting for walking speed and barefoot loading. Findings For the foot as a whole, there were no differences in off-loading between the two techniques. Subjects wearing cast walker boots had greater reductions in forefoot peak pressure, pressure-time integral, maximum force, and force-time integral with respect to barefoot walking. Healing times were similar between groups, but a greater proportion of ulcers healed in total contact casting compared to cast walker boots. Interpretation In subjects with diabetes, peripheral neuropathy, and plantar ulceration, cast walker boots provided greater load reduction in the forefoot, the most frequent site of diabetic ulceration, though a greater proportion of subjects wearing total contact casts experienced ulcer healing. Taken together, the less effective ulcer healing in cast walker boots despite superior forefoot off-loading suggests an important role for patient compliance in ulcer healing. PMID:21496977

  17. Change in the size of Walker Lake during the past 5000 years

    USGS Publications Warehouse

    Benson, L.V.; Meyers, P.A.; Spencer, R.J.

    1991-01-01

    In 1984, a 12-m sediment core (WLC84-8) was taken from the deepest part of Walker Lake. Samples of the core were analysed for diatoms, pollen, carbonate mineralogy, magnesium content, ??18O and ??13C values of the total inorganic fractin, ??18O and ??13C values of Limnocythere ceriotuberosa, ??13C values of the total organic fraction, grain size, and magnetic susceptibility. The data indicate that Walker Lake became shallow and probably desiccated between ???5300-4800 and 2700-2100 yr B.P.. Each of the organic and inorganic proxy indicators of lake size discussed in this paper was useful in determining the presence of the shallow-lake intervals. However, none of the indicators was useful in determining the cause of the shallow-lake intervals. Instead, the types of fish living in Walker Lake prior to 1940 were used to demonstrate that shallow-lake intervals resulted from diversion of the Walker River and not from climatic aridity. Major changes in mineralogy and magnesium content of carbonates and major changes in diatom populations with time were found to be a function of the chemical evolution of Walker Lake combined with changing lake size. The stable isotopes of oxygen and carbon were found to be good indicators of lake volume changes. A lake-level record for Walker Lake constructed from stable-isotope data was found to be similar to a lake-level record constructed using tufa and tree-stump data. Both records indicate relatively high lake levels between 4800-2700 yr B.P., at 1250 yr B.P., and within the last 300 yr. Substantial declines in lake level occurred ???2000 and ???1000 yr B.P. ?? 1991.

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

    NASA Astrophysics Data System (ADS)

    Burn, David M.; Atkinson, Del

    2013-06-01

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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    O'Donoghue, S. J.; Bray, A. J.

    2002-05-01

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

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

    ... PIONEER at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico in the Federal Register (74 FR... Continental Shelf FPSO, Gulf of Mexico AGENCY: Coast Guard, DHS. ACTION: Final rule. SUMMARY: The Coast Guard... (FPSO) system, at Walker Ridge 249 in the Outer Continental Shelf. The purpose of the safety zone is...

  3. 77 FR 67811 - Porter-Walker LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-14

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

  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

    ..., 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)....

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

    PubMed

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

    2014-12-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  8. 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...

  9. 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...

  10. 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...

  11. 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...

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  14. 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)

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

    PubMed Central

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

    2016-01-01

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

  16. 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...

  17. 75 FR 24753 - The Walker Auto Group, Inc., Miamisburg, OH; Notice of Negative Determination Regarding...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ... Notice of determination was published in the Federal Register on February 16, 2010 (75 FR 7039). Pursuant... Walker Auto Group, Inc., Miamisburg, Ohio, supplies a service (sales and service of Pontiac automobiles... states that the ``well-documented * * * import of foreign-made automobiles has increased continually...

  18. 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…

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

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    ERIC Educational Resources Information Center

    Sadoff, Diane F.

    1985-01-01

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

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

    ERIC Educational Resources Information Center

    Baumrind, Diana

    1986-01-01

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

  3. 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.

  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. 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

  6. 33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... below the surface of the water within the boundaries of this security zone. ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Security Zone: Walkers Point... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS...

  7. 33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... below the surface of the water within the boundaries of this security zone. ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone: Walkers Point... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS...

  8. 33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... below the surface of the water within the boundaries of this security zone. ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone: Walkers Point... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS...

  9. 33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... below the surface of the water within the boundaries of this security zone. ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone: Walkers Point... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS...

  10. 33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... below the surface of the water within the boundaries of this security zone. ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Security Zone: Walkers Point... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED ACCESS...

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

    PubMed

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

    2003-10-01

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

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

    ERIC Educational Resources Information Center

    Bahr, Kathy

    2010-01-01

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

  13. 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…

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    ERIC Educational Resources Information Center

    Matunda, Robert Stephen Mokaya

    2009-01-01

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

  16. 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…

  17. 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)

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

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

    ERIC Educational Resources Information Center

    Sherblom, Stephen A.

    2009-01-01

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

  20. Strain Partitioning in the Northern Walker Lane and Western Basin and Range from GPS Measurements

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Blewitt, G.; Kreemer, C.

    2009-05-01

    The northern Walker Lane, in the western Basin and Range Province of the United States, is a complex system of dextral, normal and sinestral faults that work together to accommodate approximately 9 mm/yr of relative motion between the Sierra Nevada/Great Valley block and the more slowly extending Province. GPS measurements made using the BARGEN, EarthScope PBO and MAGNET GPS networks since 2004 are now providing improved resolution of deformation patterns and crustal fault slip rates inside the Walker Lane and western Basin and Range. We have processed all the GPS data as part of a uniform global solution, and filtered the solution on a Great Basin spatial scale to obtain rates of motion of the Walker Lane crust with respect to North America. Using these rates we have constrained slip rates on regional faults using a block model whose boundaries conform to Quaternary surface rupture geometries. These results show a very strong correlation between the geologic domains and style of strain measured with GPS. In particular, east of the Walker Lane, where the topography and crustal faulting are characteristic of classic Basin and Range tectonic extension, the GPS velocities show a highly uniform southeast to northwest uniaxial extension of 2.5 mm/yr distributed over 250 km. This uniform extension implies normal slip rates of approximately 0.1 mm/yr on average for each fault (horizontal extension). The transition between Basin and Range morphology and the Walker Lane is matched in the GPS velocities by a transition from uniaxial extension to transtension that is resolved into dextral slip on northwest trending faults, with minor contributions from left lateral slip on northeast striking faults and normal slip. Right oblique extension is well-distributed across the Walker Lane, with most faults contributing some slip to accommodate the overall slip budget. The greatest slip rates occur on the western and eastern margins, and by far the greatest amount of normal slip

  1. 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

  2. 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

  3. 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

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    PubMed

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

    2016-05-27

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

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

    PubMed

    Baumrind, D

    1986-04-01

    Data from the Family Socialization and Developmental Competence Project are used to probe Walker's conclusion that there are no sex differences in moral reasoning. Ordinal and nominal nonparametric statistics result in a complex but theoretically meaningful network of relationships among sex, educational level, and Kohlberg stage score level, with the presence and direction of sex differences in stage score level dependent on educational level. The effects on stage score level of educational level and working status are also shown to differ for men and women. Reasons are considered for not accepting Walker's dismissal of studies that use (a) a pre-1983 scoring manual, or (b) fail to control for education. The problems presented to Kohlberg's theory by the significant relationship between educational and stage score levels in the general population are discussed, particularly as these apply to the postconventional level of moral reasoning. PMID:3956321

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

    USGS Publications Warehouse

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Stoica, Ovidiu Cristinel

    2016-01-01

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

  11. Feynman-Kac Equation for Convection-Dispersion with Mobile and Immobile Walkers

    NASA Astrophysics Data System (ADS)

    Choquet, C.; Neel, M. C.

    2012-07-01

    Some experiments for determining transport properties are based on distributions data of paths integrals of particles undergoing displacement. Unfortunately occurrence of abnormally long immobile periods renders the celebrated Feynman-Kac equation inappropriate to rule the joint density of positions and path integrals of walkers. Nevertheless, a natural partition of the distribution of particles (mobile and immobile) may then be reunified by a fractional integral operator. An adequate Feynman-Kac type's equation follows from mass conservation principle.

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

    PubMed

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

    1985-02-01

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

  13. Studies of the properties of human origin recognition complex and its Walker A motif mutants.

    PubMed

    Giordano-Coltart, Jennifer; Ying, Carol Y; Gautier, Jean; Hurwitz, Jerard

    2005-01-01

    The eukaryotic six-subunit origin recognition complex (ORC) governs the initiation site of DNA replication and formation of the prereplication complex. In this report we describe the isolation of the wild-type Homo sapiens (Hs)ORC and variants containing a Walker A motif mutation in the Orc1, Orc4, or Orc5 subunit using the baculovirus-expression system. Coexpression of all six HsORC subunits yielded a stable complex containing HsOrc subunits 1-5 (HsORC1-5) with virtually no Orc6 protein (Orc6p). We examined the ATPase, DNA-binding, and replication activities of these complexes. Similar to other eukaryotic ORCs, wild-type HsORC1-5 possesses ATPase activity that is stimulated only 2-fold by single-stranded DNA. HsORC1-5 with a mutated Walker A motif in Orc1p contains no ATPase activity, whereas a similar mutation of either the Orc4 or Orc5 subunit did not affect this activity. The DNA-binding activity of HsORC1-5, using lamin B2 DNA as substrate, is stimulated by ATP 3- to 5-fold. Mutations in the Walker A motif of Orc1p, Orc4p, or Orc5p reduced the binding efficiency of HsORC1-5 modestly (2- to 5-fold). Xenopus laevis ORC-depleted extracts supplemented with HsORC1-5 supported prereplication complex formation and X. laevis sperm DNA replication, whereas the complex with a mutation in the Walker A motif of the Orc1, Orc4, or Orc5 subunit did not. These studies indicate that the ATP-binding motifs of Orc1, Orc4, and Orc5 are all essential for the replication activity associated with HsORC. PMID:15618391

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  15. Back reaction of a long range force on a Friedmann-Robertson-Walker background

    SciTech Connect

    Brisudova, Martina; Kinney, William H.

    2000-11-15

    It is possible that there may exist long-range forces in addition to gravity. In this paper we construct a simple model for such a force based on exchange of a massless scalar field and analyze its effect on the evolution of a homogeneous Friedmann-Robertson-Walker cosmology. The presence of such an interaction leads to an equation of state characterized by positive pressure and to resonant particle production similar to that observed in preheating scenarios.

  16. 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…

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

    PubMed

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

    2014-01-01

    Ricania speculum (Walker, 1851) (Hemiptera: Fulgoromorpha: Ricaniidae) is reported for the first time in Europe. Both nymphs and adults were observed from 2009 in several municipalities of Liguria (Italy). Since the species is extremely polyphagous and is a real pest for several crops in tropical and subtropical areas, the presence of this alien insect is noteworthy, representing a new possible threat for native species and human activities.  PMID:25283410

  18. Toward improving our understanding of climate change during the Medieval Climatic Anomaly using hydrologic models of the Walker River Basin

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Walker lake, similar to other closed basin lakes in the mid-latitudinal dry lands, serves as an indicator of past climate change before the hydrologic system of the basin was altered through agricultural activities beginning in the mid to late 1800s. There have been a number of studies aimed at collecting a diverse set of proxy data to better understand the lake level fluctuations of Walker Lake during the Holocene. These data sets include biological proxies such as diatom, ostracod, pollen sources, isotope dating of sediment cores, sediment chemistry, paleomagnetic susceptibility, the dating of tufa deposits and analysis of stromatolites from the lake shores, near lake tree stump and shrub evidence, and geomorphological evidence of various lake stages. Lake level chronologies have been developed and reported based on this diverse set of proxy information. In this study, a simple, spatially distributed hydrologic model was applied to the Walker River Basin from the headwaters in the Sierra Nevada to the terminus at Walker Lake to simulate the watershed and lake responses associated with changes in precipitation and temperature. Experiments were conducted with the model to better understand how the climate might have been different (compared with the modern 30-year normal values) during the Medieval Climatic Anomaly (MCA). The model was also used to investigate previously reported hypotheses that at times during or near the MCA, the Walker River may have been diverted through Adrian Gap into the Carson Sink leading to decreasing lake levels and even desiccation of Walker Lake. Our modeling results indicate that the MCA low stand lake levels can be sustained with 60% to 70% of modern precipitation and that it is unlikely that the low levels of Walker Lake during the MCA were a result of a breakout of the Walker River at Adrian Gap.

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

    NASA Astrophysics Data System (ADS)

    Rigovacca, L.; di Franco, C.

    2016-02-01

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

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

    PubMed Central

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

    2011-01-01

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

  1. 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.

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

    PubMed

    Rigovacca, L; Di Franco, C

    2016-01-01

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

  3. 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.

  4. Reliability of the Walker Cranial Nonmetric Method and Implications for Sex Estimation.

    PubMed

    Lewis, Cheyenne J; Garvin, Heather M

    2016-05-01

    The cranial trait scoring method presented in Buikstra and Ubelaker (Standards for data collection from human skeletal remains. Fayetteville, AR: Arkansas Archeological Survey Research Series No. 44, 1994) and Walker (Am J Phys Anthropol, 136, 2008 and 39) is the most common nonmetric cranial sex estimation method utilized by physical and forensic anthropologists. As such, the reliability and accuracy of the method is vital to ensure its validity in forensic applications. In this study, inter- and intra-observer error rates for the Walker scoring method were calculated using a sample of U.S. White and Black individuals (n = 135). Cohen's weighted kappas, intraclass correlation coefficients, and percentage agreements indicate good agreement between trials and observers for all traits except the mental eminence. Slight disagreement in scoring, however, was found to impact sex classifications, leading to lower accuracy rates than those published by Walker. Furthermore, experience does appear to impact trait scoring and sex classification. The use of revised population-specific equations that avoid the mental eminence is highly recommended to minimize the potential for misclassifications. PMID:27122414

  5. 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.

  6. HitWalker2: visual analytics for precision medicine and beyond

    PubMed Central

    Bottomly, Daniel; McWeeney, Shannon K.; Wilmot, Beth

    2016-01-01

    Summary: The lack of visualization frameworks to guide interpretation and facilitate discovery is a potential bottleneck for precision medicine, systems genetics and other studies. To address this we have developed an interactive, reproducible, web-based prioritization approach that builds on our earlier work. HitWalker2 is highly flexible and can utilize many data types and prioritization methods based upon available data and desired questions, allowing it to be utilized in a diverse range of studies such as cancer, infectious disease and psychiatric disorders. Availability and implementation: Source code is freely available at https://github.com/biodev/HitWalker2 and implemented using Python/Django, Neo4j and Javascript (D3.js and jQuery). We support major open source browsers (e.g. Firefox and Chromium/Chrome). Contact: wilmotb@ohsu.edu Supplementary information: Supplementary data are available at Bioinformatics online. Additional information/instructions are available at https://github.com/biodev/HitWalker2/wiki PMID:26708334

  7. Quantifying Walker River stream temperature variability using distributed temperature sensing data

    NASA Astrophysics Data System (ADS)

    Beck, A. J.; Null, S. E.

    2014-12-01

    Nevada's Walker River historically supported Lahontan cutthroat trout (Oncorhynchus clarki henshawi), although today Lahontan cutthroat trout are listed as a federally threatened species and limited to isolated headwater reaches. Much of the lower Walker River is impaired for native aquatic species because of elevated stream temperatures and nutrients, and low streamflow and dissolved oxygen levels. We deployed a 1 kilometer single-ended fiber-optic Raman spectra distributed temperature sensing (DTS) cable in the Wabuska drain outlet and surrounding Walker River for one week in June 2014 to improve fine-scale understanding of stream temperatures. These data identify and quantify thermal variability of micro-habitat that standard temperature monitoring and modeling do not capture. Results indicate stream temperatures exceeded 26°C and a return flow channel exhibited greater thermal variability with both warmer daytime temperatures and cooler nighttime temperatures - possibly providing more complex thermal habitat during some flow conditions. Fine-scale DTS data complement ongoing stream temperature modeling by bounding thermal variability within model reaches that are 250 m long and where stream temperature is assumed to be well-mixed within each reach.

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

    PubMed Central

    Rigovacca, L.; Di Franco, C.

    2016-01-01

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

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

    PubMed

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

    2008-05-01

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

  10. Eupolyphaga sinensis Walker demonstrates angiogenic activity and inhibits A549 cell growth by targeting the KDR signaling pathway.

    PubMed

    Dai, Bingling; Qi, Junpeng; Liu, Rui; Zhang, Yanmin

    2014-09-01

    Eupolyphaga sinensis Walker has been reported to have anticoagulation, antithrombotic, liver protective and antitumor effects. In the present study, the inhibitory effects on proliferation of A549 human non‑small cell lung cancer cells and the underlying mechanisms were examined. Firstly, three solvents, 70% ethanol, distilled water and 95% ethanol, were used to extract Eupolyphaga sinensis Walker. The MTT assay results demonstrated that the 70% ethanol extract more potently reduced the growth of A549 cells and it was therefore adopted in the subsequent experiments. Eupolyphaga sinensis Walker 70% ethanol extract significantly inhibited A549 cell migration in a time‑ and dose‑dependent manner and inhibited human umbilical vein endothelial cell proliferation, migration and tube formation. Furthermore, Eupolyphaga sinensis Walker 70% ethanol extract effectively inhibited blood vessel formation in the established tissue model for angiogenesis. In addition, Eupolyphaga sinensis Walker 70% ethanol extract was demonstrated to inhibit the autophosphorylation of KDR, and downregulate the subsequent activation of AKT and extracellular signal regulated kinase (ERK)1/2 in A549 cells. In conclusion, these findings demonstrated that the antitumor mechanism of Eupolyphaga sinensis Walker 70% ethanol extract was through inhibiting angiogenesis. It functioned by interrupting the autophosphorylation of KDR and subsequently, AKT and ERK1/2. PMID:25059654

  11. 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

  12. 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

  13. 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)

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

    PubMed

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

    2015-05-01

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

  15. 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 ωm. While still alive, the creeper has a finite mean frequency ω of change of the direction of motion. In particular, we consider the efficiency of the target search process, characterized by the probability that the creeper will eventually detect the target. Analytic results confirmed by numerical results show that there is an ωm-dependent optimal frequency ω =ωopt 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.

  16. Friedmann-Robertson-Walker models do not require zero active mass

    NASA Astrophysics Data System (ADS)

    Kim, Do Young; Lasenby, Anthony N.; Hobson, Michael P.

    2016-04-01

    The Rh = ct cosmological model has received considerable attention in recent years owing to claims that it is favoured over the standard Λ cold dark mater (ΛCDM) model by most observational data. A key feature of the Rh = ct model is that the zero active mass condition ρ + 3p = 0 holds at all epochs. Most recently, Melia (2016b) has claimed that this condition is a requirement of the symmetries of the Friedmann-Robertson-Walker (FRW) spacetime. We demonstrate that this claim is false and results from a flaw in the logic of Melia's argument.

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

    NASA Astrophysics Data System (ADS)

    Chen, Hong-Bo; Li, You-Quan

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Crasmareanu, Mircea; Frigioiu, Camelia

    2015-07-01

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

  19. 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.

  20. Novel cyclovirus discovered in the Florida woods cockroach Eurycotis floridana (Walker).

    PubMed

    Padilla-Rodriguez, Marco; Rosario, Karyna; Breitbart, Mya

    2013-06-01

    A novel cyclovirus (proposed genus "Cyclovirus", family Circoviridae) was discovered in a specimen of Eurycotis floridana (Walker), also known as the Florida woods cockroach or palmetto bug, collected from Tarpon Springs, Florida. The Florida woods cockroach-associated cyclovirus GS140 (FWCasCyV-GS140) was obtained through a degenerate PCR assay and showed 64 % genome-wide pairwise identity to a cyclovirus identified in bat feces. This finding supports recent reports suggesting that Circoviridae members, traditionally thought to only infect vertebrates, are present within insect populations. PMID:23358613

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Zhu, Tao; Ren, Ji-Rong

    2009-07-01

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

  3. Analysis of Confined Random Walkers with Applications to Processes Occurring in Molecular Aggregates and Immunological Systems.

    PubMed

    Chase, Matthew; Spendier, Kathrin; Kenkre, V M

    2016-03-31

    Explicit solutions are presented in the Laplace and time domains for a one-variable Fokker-Planck equation governing the probability density of a random walker moving in a confining potential. Illustrative applications are discussed in two unrelated physical contexts: quantum yields in a doped molecular crystal or photosynthetic system, and the motion of signal receptor clusters on the surface of a cell encountered in a problem in immunology. An interesting counterintuitive effect concerning the consequences of confinement is found in the former, and some insights into the driving force for microcluster centralization are gathered in the latter application. PMID:26885727

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  5. Friedmann-Robertson-Walker models do not require zero active mass

    NASA Astrophysics Data System (ADS)

    Kim, Do Young; Lasenby, Anthony N.; Hobson, Michael P.

    2016-07-01

    The Rh = ct cosmological model has received considerable attention in recent years owing to claims that it is favoured over the standard Λ cold dark mater (ΛCDM) model by most observational data. A key feature of the Rh = ct model is that the zero active mass condition ρ + 3p = 0 holds at all epochs. Most recently, Melia has claimed that this condition is a requirement of the symmetries of the Friedmann-Robertson-Walker spacetime. We demonstrate that this claim is false and results from a flaw in the logic of Melia's argument.

  6. Why walkers slip: shine is not a reliable cue for slippery ground.

    PubMed

    Joh, Amy S; Adolph, Karen E; Campbell, Margot R; Eppler, Marion A

    2006-04-01

    In a series of four studies, we investigated the visual cues that walkers use to predict slippery ground surfaces and tested whether visual information is reliable for specifying low-friction conditions. In Study 1, 91% of participants surveyed responded that they would use shine to identify upcoming slippery ground. Studies 2-4 confirmed participants' reliance on shine to predict slip. Participants viewed ground surfaces varying in gloss, paint color, and viewing distance under indoor and outdoor lighting conditions. Shine and slip ratings and functional walking judgments were related to surface gloss level and to surface coefficient of friction (COF). However, judgments were strongly affected by surface color, viewing distance, and lighting conditions--extraneous factors that do not change the surface COF. Results suggest that, although walkers rely on shine to predict slippery ground, shine is not a reliable visual cue for friction. Poor visual information for friction may underlie the high prevalence of friction-related slips and falls. PMID:16900828

  7. 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.

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

    PubMed

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

    2016-01-01

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

  9. Eupolyphaga sinensis walker displays inhibition on hepatocellular carcinoma through regulating cell growth and metastasis signaling.

    PubMed

    Zhang, Yanmin; Zhan, Yingzhuan; Zhang, Dongdong; Dai, Bingling; Ma, Weina; Qi, Junpeng; Liu, Rui; He, Langchong

    2014-01-01

    Tumor growth and metastasis are responsible for most cancer patients' deaths. Here, we report that eupolyphaga sinensis walker has an essential role in resisting hepatocellular carcinoma growth and metastasis. Compared with proliferation, colony formation, transwell assay and transplantable tumor in nude mouse in vitro and vivo, eupolyphaga sinensis walker extract (ESWE) showed good inhibition on the SMMC-7721 cell growth and metastasis. Using genome-wide microarray analysis, we found the down-regulated growth and metastasis factors, and selected down-regulated genes were confirmed by real-time PCR. Knockdown of a checkpoint PKCβ by siRNA significantly attenuated tumor inhibition and metastasis effects of ESWE. Moreover, our results indicate ESWE inhibits HCC growth by not only downregulating the signaling of PKCβ, Akt, m-TOR, Erk1/2, MEK-2, Raf and JNK-1, but also increasing cyclin D1 protein levels and decreasing amount of cyclin E, cyclin B1 and cdc2 of the cycle proteins. At the same time, ESWE reduced MMP2, MMP9 and CXCR4, PLG, NFκB and P53 activities. Overall, our studies demonstrate that ESWE is a key factor in growth and metastasis signaling inhibitor targeting the PKC, AKT, MAPK signaling and related metastasis signaling, having potential in cancer therapy. PMID:24980220

  10. Bobble-head doll syndrome associated with Dandy-Walker syndrome. Case report.

    PubMed

    de Brito Henriques, José Gilberto; Henriques, Karina Santos Wandeck; Filho, Geraldo Pianetti; Fonseca, Luiz Fernando; Cardoso, Francisco; Da Silva, Márcia Cristina

    2007-09-01

    Bobble-head doll syndrome (BHDS) presents in childhood and is usually associated with lesions of the third ventricle. This disorder is characterized by stereotypical head movements of the type "yes-yes" (up and down) at a frequency of 2 to 3 Hz. Rarely, movements of the type "no-no" (side-to-side) are described. There are a few hypotheses to explain the mechanism responsible for BHDS, but its real pathophysiological characteristics are still unknown. The authors describe the case of a child born with hydrocephalus and Dandy-Walker syndrome. A ventriculoperitoneal shunt was implanted in the child because of progressive head enlargement. One year after shunt placement, she began making frequent horizontal head movements of the type "no-no". There were no other signs or symptoms. Imaging studies demonstrated small ventricles and a posterior fossa cyst with no signs of hypertension. The child's growth, development, and head circumference (within the 5th percentile) remained satisfactory. Three aspects of this case were of interest: the association of BHDS with Dandy-Walker syndrome, the rare occurrence of BHDS of the "no-no" type, and the absence of third ventricle dilation. The authors' findings support the hypothesis that cerebellar malformations themselves can PMID:17918536

  11. Disentangling the ambiguity of the lagged correlation function - analysis of the Walker circulation mechanism

    NASA Astrophysics Data System (ADS)

    Runge, Jakob; Kurths, Jürgen

    2013-04-01

    A first step towards the investigation of tropical climate variability and teleconnections is the analysis of observations. Lagged correlation analysis is commonly used to gain insights into interaction mechanisms between climatological processes, in particular to determine the time delay and strength of a mechanism. In this talk, such an analysis is discussed on the mechanism of the Walker circulation. The influence of serial correlation on lagged correlation functions and regressions is investigated and it is demonstrated how this influence can lead to ambiguous and misleading conclusions about the time delay and strength of an interaction mechanism. To overcome the issues arising in interpreting the lag and strength of a correlation, we propose to use graphical models that encode the lag-specific causality between multiple processes. In this framework a certain partial correlation measure is derived that allows to very specifically measure the time delay and strength of a coupling mechanism. This approach is then shown to yield a more precise picture of the interaction mechanism of the Walker circulation. The talk is intended to serve as a guideline to interpret lagged correlations and regressions and introduces a more powerful approach to analyze time delays and strengths of interaction mechanisms.

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

    NASA Astrophysics Data System (ADS)

    Rambeau, Joachim; Schehr, Grégory

    2011-06-01

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

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

    NASA Astrophysics Data System (ADS)

    McClung, B.

    2015-12-01

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

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

    PubMed Central

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

    2016-01-01

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

  15. Accommodation of missing shear strain in the Central Walker Lane, western North America: Constraints from dense GPS measurements

    NASA Astrophysics Data System (ADS)

    Bormann, Jayne M.; Hammond, William C.; Kreemer, Corné; Blewitt, Geoffrey

    2016-04-01

    We present 264 new interseismic GPS velocities from the Mobile Array of GPS for Nevada Transtension (MAGNET) and continuous GPS networks that measure Pacific-North American plate boundary deformation in the Central Walker Lane. Relative to a North America-fixed reference frame, northwestward velocities increase smoothly from ∼4 mm/yr in the Basin and Range province to 12.2 mm/yr in the central Sierra Nevada resulting in a Central Walker Lane deformation budget of ∼8 mm/yr. We use an elastic block model to estimate fault slip and block rotation rates and patterns of deformation from the GPS velocities. Right-lateral shear is distributed throughout the Central Walker Lane with strike-slip rates generally <1.5 mm/yr predicted by the block model, but extension rates are highest near north-striking normal faults found along the Sierra Nevada frontal fault system and in a left-stepping, en-echelon series of asymmetric basins that extend from Walker Lake to Lake Tahoe. Neotectonic studies in the western Central Walker Lane find little evidence of strike-slip or oblique faulting in the asymmetric basins, prompting the suggestion that dextral deformation in this region is accommodated through clockwise block rotations. We test this hypothesis and show that a model relying solely on the combination of clockwise block rotations and normal faulting to accommodate dextral transtensional strain accumulation systematically misfits the GPS data in comparison with our preferred model. This suggests that some component of oblique or partitioned right-lateral fault slip is needed to accommodate shear in the asymmetric basins of the western Central Walker Lane. Present-day clockwise vertical axis rotation rates in the Bodie Hills, Carson Domain, and Mina Deflection are between 1-4°/Myr, lower than published paleomagnetic rotation rates, suggesting that block rotation rates have decreased since the Late to Middle Miocene.

  16. The Dependence of the Low-Level Equatorial Easterly Jet on Hadley and Walker Circulations.

    NASA Astrophysics Data System (ADS)

    Battisti, David S.; Ovens, David D.

    1995-11-01

    How the time-mean Hadley and Walker circulations affect the formation of a low-level equatorial easterly jet is investigated. Experiments are conducted for equinoctial conditions using a general circulation model, the Community Climate Model (CCM1), that includes a Kuo convective scheme and a lower boundary that is specified to be water at a fixed sea surface temperature (SST). Several zonally symmetric SST forcings are used to determine how various Hadley circulations affect the tropical zonal wind field. A zonal wavenumber one equatorial SST anomaly superimposed on a zonally symmetric SST distribution forces a wind field that includes both Hadley and Walker circulations.The Hadley circulation experiments produce equatorial easterlies and low-level jets on the poleward sides of the intertropical convergence zone (ITCZ) 10° to 15° from the equator. In an experiment with a single, dominant off-equatorial ITCZ in the Northern Hemisphere, the Southern Hemisphere jet moves to within 7.5° of the equator; yet none of the Hadley circulation cases produce a low-level easterly jet on the equator because they lack a mechanism to vertically confine the flow.The experiment that includes a zonally overturning cell on the equator produces a low-level equatorial easterly jet in the cold tongue region that is similar to the observed jet over the central to eastern Pacific. That case shows that east of the equatorial warm pool the Walker circulation and its induced Kelvin wave response provide the necessary upper-level westerly flow and subsidence to vertically confine the low-level easterlies into a jet. Spring and fall climatological runs of the CCMI with land surfaces, seasonally varying SSTs and insolation, and a moist convective adjustment scheme support the hypothesis that the Walker circulation provides the vertical confinement necessary to form a low-level equatorial easterly jet in the region east of the equatorial convective center, regardless of the Hadley circulation

  17. The Dirac equation and the normalization of its solutions in a closed Friedmann- Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Finster, Felix; Reintjes, Moritz

    2009-05-01

    We set up the Dirac equation in a Friedmann-Robertson-Walker geometry and separate the spatial and time variables. In the case of a closed universe, the spatial dependence is solved explicitly, giving rise to a discrete set of solutions. We compute the probability integral and analyze a spacetime normalization integral. This analysis allows us to introduce the fermionic projector in a closed Friedmann-Robertson-Walker geometry and to specify its global normalization as well as its local form. First author supported in part by the Deutsche Forschungsgemeinschaft.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. Breast Cancer Mortality vs. Exercise and Breast Size in Runners and Walkers

    PubMed Central

    Williams, Paul T.

    2013-01-01

    Purpose Identify predictors of breast cancer mortality in women who exercised below (<7.5 metabolic equivalent hours/week, MET-hours/wk), at (7.5 to 12.5 MET-hours/wk), or above (≥12.5 MET-hours/wk) recommended levels. Methods Cox proportional hazard analyses of baseline pre-diagnosis MET-hours/wk vs. breast cancer mortality adjusted for follow-up age, race, baseline menopause, and estrogen and oral contraceptive use in 79,124 women (32,872 walkers, 46,252 runners) from the National Walkers' and Runners' Health Studies. Results One-hundred eleven women (57 walkers, 54 runners) died from breast cancer during the 11-year follow-up. The decline in mortality in women who exercised ≥7.5 MET-hours/wk was not different for walking and running (P = 0.34), so running and walking energy expenditures were combined. The risk for breast cancer mortality was 41.5% lower for ≥7.5 vs. <7.5 MET-hours/wk (HR: 0.585, 95%CI: 0.382 to 0.924, P = 0.02), which persisted when adjusted for BMI (HR: 0.584, 95%CI: 0.368 to 0.956, P = 0.03). Other than age and menopause, baseline bra cup size was the strongest predictor of breast cancer mortality, i.e., 57.9% risk increase per cup size when adjusted for MET-hours/wk and the other covariates (HR: 1.579, 95%CI: 1.268 to 1.966, P<0.0001), and 70.4% greater when further adjusted for BMI (HR: 1.704, 95%CI: 1.344 to 2.156, P = 10−5). Breast cancer mortality was 4.0-fold greater (HR: 3.980, 95%CI: 1.894 to 9.412, P = 0.0001) for C-cup, and 4.7-fold greater (HR: 4.668, 95%CI: 1.963 to 11.980, P = 0.0004) for ≥D-cup vs. A-cup when adjusted for BMI and other covariates. Adjustment for cup size and BMI did not eliminate the association between breast cancer mortality and ≥7.5 MET-hour/wk walked or run (HR: 0.615, 95%CI: 0.389 to 1.004, P = 0.05). Conclusion Breast cancer mortality decreased in association with both meeting the exercise recommendations and smaller breast volume. PMID:24349006

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  2. A review of the genus Cyana Walker, 1854 (Lepidoptera, Erebidae, Arctiinae) from Cambodia, with description of new species.

    PubMed

    Bayarsaikhan, Ulziijargal; Bae, Yang-Seop

    2016-01-01

    Genus Cyana Walker, 1854, with 17 species in Cambodia, is reviewed. Among them, Cyana angkorensis Bayarsaikhan & Bae, sp. n. is described as new to science and 7 species are newly recorded from Cambodia. A key to the Cambodian species of the genus Cyana with illustrations of adults and genitalia is presented. PMID:27395140

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

    PubMed Central

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

    2013-01-01

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

  4. 75 FR 49517 - Notice of Intent To Prepare an Environmental Impact Statement for the Walker Ridge Wind Project...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ...-kilovolt (kV) distribution system. The proposed action would include up to 42 wind turbine generators, an... Ridge Wind Project, Lake and Colusa Counties, CA Agency: Bureau of Land Management, Interior. ACTION... the Draft EIS. ADDRESSES: You may submit comments related to the Walker Ridge Wind Project by any...

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  6. 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…

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

    PubMed

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

    2014-03-01

    We examined the effects of vitamin E supplementation (VES) on osteoclast (OC) resorbing activity and cytomorphometry in Walker 256/B tumor osteolytic rats. Twenty-four aged male rats were randomized into 3 groups: 6 were sham operated; 9 were injected in the right hind limb with Walker 256/B cells (W256 group); and 9 were injected as above and supplemented with VE (45mg/kg BW) (W256VE group). Twenty days later, bone mass (BV/TV) and some microarchitectural parameters were assessed. Some histodynamic parameters, cellular and nuclear form factors (FFC and FFN), and nuclear-cytoplasmic ratio (N/C) of OC were measured for each group. W256 group exhibited osteolytic lesions in the operated femora. Walker 256/B induced trabecular perforation and decreased BV/TV associated with significant increases in OC numbering (N.Oc/B.Ar and Oc.N/B.Pm) and activity (ES/BS and Oc.S/BS). While FFN remain unchanged, the FFC and N/C ratio increased in the W256 group. W256VE showed less osteolytic lesions. Moreover, disruption of bone microarchitecture and OC activity in W256VE group decreased. VES reduced the malignant Walker 256/B-induced enhanced OC resorbing activity with cytoinhibition rate reaching 41%. The protective effect of VE may be due to its modulation of OC cytomorphometry and subsequently their activity. PMID:24314812

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

    ERIC Educational Resources Information Center

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

    2013-01-01

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

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

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  10. CMIP5 simulated change in the intensity of the Hadley and Walker circulations from the perspective of velocity potential

    NASA Astrophysics Data System (ADS)

    Zhou, Botao; Shi, Ying; Xu, Ying

    2016-07-01

    Based on the simulations of 31 global models in CMIP5, the performance of the models in simulating the Hadley and Walker circulations is evaluated. In addition, their change in intensity by the end of the 21st century (2080-2099) under the RCP4.5 and RCP8.5 scenarios, relative to 1986-2005, is analyzed from the perspective of 200 hPa velocity potential. Validation shows good performance of the individual CMIP5 models and the multi-model ensemble mean (MME) in reproducing the meridional (zonal) structure and magnitude of Hadley (Walker) circulation. The MME can also capture the observed strengthening tendency of the winter Hadley circulation and weakening tendency of the Walker circulation. Such secular trends can be simulated by 39% and 74% of the models, respectively. The MME projection indicates that the winter Hadley circulation and the Walker circulation will weaken under both scenarios by the end of the 21st century. The weakening amplitude is larger under RCP8.5 than RCP4.5, due to stronger external forcing. The majority of the CMIP5 models show the same projection as the MME. However, for the summer Hadley circulation, the MME shows little change under RCP4.5 and large intermodel spread is apparent. Around half of the models project an increase, and the other half project a decrease. Under the RCP8.5 scenario, the MME and 65% of the models project a weakening of the summer southern Hadley circulation.

  11. "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…

  12. Nasopharyngeal teratoma ('hairy polyp'), Dandy-Walker malformation, diaphragmatic hernia, and other anomalies in a female infant.

    PubMed Central

    Aughton, D J; Sloan, C T; Milad, M P; Huang, T E; Michael, C; Harper, C

    1990-01-01

    Nasopharyngeal teratomas are rare and are infrequently associated with extra-oral malformations. The case of a premature female infant with multiple congenital anomalies, including nasopharyngeal teratoma, Dandy-Walker malformation, diaphragmatic hernia, and congenital heart defect, is presented. This constellation of malformations does not appear to have been reported previously. Images PMID:2074566

  13. 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...

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

    PubMed

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

    2016-01-01

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

  15. Holoprosencephaly with Dandy-Walker cyst. Rare coexistence of two major malformations.

    PubMed

    Kurokawa, Y; Tsuchita, H; Sohma, T; Kitami, K; Takeda, T; Hattori, S

    1990-01-01

    A case of holoprosencephaly associated with Dandy-Walker cyst is reported. The patient was a male baby whose mother had normal serum titers for toxoplasma, syphilis, rubella and hepatitis B. She had no history of diabetes mellitus, administration of drugs or irradiation during the pregnancy. At the 8th month of gestation, fetal hydrocephalus was diagnosed by ultrasonic imaging. He was delivered by caesarean section at 34 weeks and 4 days, weighing 2,644 g. His head circumference was 42 cm; the anterior fontanel was not distended and its tension was normal. The chromosomal karyotype was a normal 46 XY. X-ray CT showed a large dorsal sac cyst in the supratentorial space and a hypoplastic cerebellum with a large cyst in the posterior fossa. He received a cyst-peritoneal shunt 24 days after birth. After this procedure, his head enlargement was arrested. We discuss the etiology of this rare coexistence of two major malformations. PMID:2178775

  16. 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).

  17. Dandy-Walker malformation and neurocutaneous melanosis in a three-month-old infant

    PubMed Central

    Swar, Mohamed Osman; Mahgoub, Shaza Mohamed; Yassin, Rehab Omer; Osman, Atika Mohamed

    2013-01-01

    Dandy-Walker Malformation (DWM) is a rare congenital malformation of the brain. It is characterized by cystic enlargement of the fourth ventricle which is communicating with an enlarged posterior fossa, cerebellar dysgenesis, high tentorial insertion and hydrocephalus. Neurocutaneous Melanosis (NCM) is a congenital neurocutaneous syndrome characterized by large or multiple melanocytic nevi and benign or malignant melanocytic tumors of the leptomeninges. We report three months old boy who presented with projectile vomiting associated with a noticeable increase in head size. Several congenital nevi were seen all over his body with evident signs of hydrocephalus. The association of DWM and NCM is a rare complex, and to our knowledge, this is the eleventh case to be reported in the literature. In this article, we discuss the proposed pathogenesis, classification and management of the condition.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  19. Establishment and characterization of a new cell line of Chilo suppressalis Walker (Lepidoptera: Pyralididae).

    PubMed

    Liu, Guangfu; Xu, Yipeng; Yu, Xiaoping

    2015-03-01

    A new cell line, designated as ZJBIQ-Chsu-I, was initiated from the fat body of larval Chilo suppressalis (Walker) (Lepidoptera: Pyralididae) in TNM-FH insect medium containing 15% fetal bovine serum. The polygonal cells (65.6%) were predominant among various cell types, and the diameter range was from 12.63 to 22.50 μm. The cell line showed a typical lepidopteran chromosome pattern ranging from 108 to 136 chromosomes in the majority of the cells. The population doubling time (PDT) of the cell line at the 15th passage was 62 h. This cell line was found to be susceptible to Spodoptera exigua nuclear polyhedrosis virus (SeNPV). By the DNA amplification fingerprinting polymerase chain reaction (DAF-PCR) technique, it was confirmed that cell line ZJBIQ-Chsu-I really originated from C. suppressalis. PMID:25381037

  20. Large Scale Dynamics of the Persistent Turning Walker Model of Fish Behavior

    NASA Astrophysics Data System (ADS)

    Degond, Pierre; Motsch, Sébastien

    2008-06-01

    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.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  3. 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.

  4. Interactions of ozone and antineoplastic drugs on rat lung fibroblasts and Walker rat carcinoma cells

    SciTech Connect

    Wenzel, D.G.; Morgan, D.L.

    1983-05-01

    Cultured rat lung fibroblasts (F-cells) and Walker rat carcinoma cells (WRC-cells) labeled with /sup 51/Cr were exposed to the following antitumor drugs alone or with O/sub 3/: carmustine (BCNU), doxorubicin (Dox), cisplatin (CPt), mitomycin C (Mit C) or vitamin K/sub 3/ (Vit K). Release of /sup 51/Cr (cell injury) was greater for F-cells than WRC-cells with any single treatment. Pretreatment with any drug (400 microM), except for Vit K with WRC-cells, did not significantly increase O/sub 3/-induced loss of /sup 51/Cr. Co-exposure of F-cells to drugs and O/sub 3/ resulted in a marked potentiation of O/sub 3/-induced injury with Vit K, and an inhibition with Dox.

  5. A Review of the Genus Miresa Walker in China (Lepidoptera: Limacodidae)

    PubMed Central

    Wu, Chun-Sheng; Solovyev, Alexey V.

    2011-01-01

    Eight species of the genus Miresa Walker are recognized in China including two new species, M. fangae Wu & Solovyev and M. polargenta Wu & Solovyev, described herein. M. burmensis Hering species is reported for the first time in China. The M. argentifera kwangtungensis Hering, 1931 taxon is raised to full specific status. The lectotypes are designated for the following 5 taxa: M. bracteata Butler, 1880 (♂, Natural History Museum, London); M. fulgida Wileman, 1910 (♂, Natural History Museum, London); M. bracteata var. orientis Strand, 1915 (♂, Rijksmuseum van Natuurlijke Historie, Leiden); M. argentifera kwangtungensis Hering, 1931 (♂, Zoologisches Museum der Humboldt Universität zu Berlin) and M. urga Hering, 1933 (♂, Zoologisches Museum der Humboldt Universität zu Berlin). The photographs of moths and their genitalia are given, a key to the Chinese species of the genus is provided, and the distributional maps are also given. PMID:21529254

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

    PubMed

    Menezes, Isis Sá; Ale-Rocha, Rosaly

    2016-01-01

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

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

    PubMed

    Ahuja, Nitin K

    2013-01-01

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

  8. Renormalizability of the functional Schroedinger picture in Robertson--Walker space-time

    SciTech Connect

    Eboli, O. ); Pi, S.; Samiullah, M.

    1989-07-01

    We study free and self-interacting scalar quantum field theories in a flat Robertson-Walker metric in the functional Schroedinger picture. We discuss Schroedinger picture quantization, relating it to conventional Heisenberg picture quantization. For the interacting theory, we introduce the time-dependent Gaussian approximation to study time evolution of pure and mixed states and we establish renormalizability of the approximation. We also study the question of computing a finite, renormalized energy-momentum tensor for both the free and the interacting theory in the Gaussian appproximation. Using the adiabatic expansion, we show that the entire subtration necessary to make the the energy-momentum tensor finite in the free theory can be written in terms of covariantly conserved tensors. We further show that the same subtraction is sufficient to make the energy-momentum tensor finite in the Gaussian approximation for the interacting theory provided that the mass and coupling constants are renromalized. {copyright} 1989 Academic Press, Inc.

  9. The Silver Peak Volcanic Center: Shoshonitic Volcanism in the Walker Lane, Western Nevada

    NASA Astrophysics Data System (ADS)

    Robinson, P. T.; Zhou, M.; Li, J.; Chen, L.; Ma, C.; Gao, J.

    2012-12-01

    Shoshonitic and high-K volcanism is widespread in the Sierra Nevada and western Nevada. The Silver Peak center, located in the Walker Lane, just east of the White Mountains, lies within the Silver Peak detachment. It consists of a subcircular volcanic complex about 15 km in diameter, with a central caldera. Volcanic activity spanned a period of 1myr from 6.0±0.5 to 4.8±0.6 Ma. The lavas range from trachybasalt to rhyolite and plot in the shoshonite field on the SiO2-K2O diagram. Oxide trends indicate relatively continuous fractionation of a parental basaltic magma. Fractionation took place in a subvolcanic magma chamber, which was periodically injected with new batches of basalt, leading to two major explosive events and resetting the fractionation processes. The first event, which erupted voluminous rhyolite ashflows, resulted in an elliptical caldera 12 by 9 km; the second produced highly feldspar-phyric trachyandesite ashflows and lavas. The most mafic lava is a trachybasalt with about 49 wt% SiO2, 7.5 wt% MgO and 2.5 wt% K2O, which contains olivine phenocrysts of Fo85. Chondrite-normalized REE patterns of the lavas show flat HREE, strong enrichment in LREE (LaN/SmN =3.5-7.7; aver. = 4.7) and variable negative Eu anomalies ranging from .21-.85. In-situ 87Sr/86Sr compositions of plagioclase grains are quite uniform, mostly between 0.7060 and 0.7070, similar to the whole-rock values (0.7061) and indicating little if any crustal contamination. We suggest that the parental magma was derived from a metasomatised mantle source by small degrees of partial melting. It was mixed periodically with new pulses of mafic magma and underwent fractional crystallization to produce the observed range of compositions. . Melting was probably triggered by transtensional deformation in the Walker Lane.

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

    SciTech Connect

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

    1989-01-01

    Samples of recent sediments, representing up to 1,000 years of accumulation, were collected from three closed basin lakes to assess the effects of brine composition on the accumulation of effects of brine composition on the accumulation of total organic carbon, the concentration of dissolved organic carbon, humic acid structure and diagenesis, and trace metal complexation. The Great Salt Lake water column is a stratified Na-Mg-Cl-SO{sub 4} brine with low alkalinity. Algal debris is entrained in the high density (1.132-1.190 g/ml) bottom brines, and in this region maximum organic matter decomposition occurs by anaerobic processes, with sulfate ion as the terminal electron acceptor. Organic matter, below 5 cm of the sediment-water interface, degrades at a very slow rate in spite of very high pore-fluid sulfate levels. Mono Lake is an alkaline (Na-CO{sub 3}-Cl-SO{sub 4}) system. The water column is stratified, but the bottom brines are of lower density relative to the Great Salt Lake, and sedimentation of algal debris is rapid. Walker Lake is also an alkaline system. The water column is not stratified, and decomposition of organic matter occurs by aerobic processes at the sediment-water interface and by anaerobic processes below. Total organic carbon and dissolved organic carbon concentrations in Walker Lake sediments vary with location and depth due to changes in input and pore-fluid sulfate concentrations. Nuclear magnetic resonance studies of humic substances and dissolved organic carbon provide information on the source of the recent sedimentary organic carbon, its relative state of decomposition, and its chemical structure. 44 refs., 10 figs., 6 tabs.

  11. 1989 Walker Branch Watershed Surveying and Mapping Including a Guide to Coordinate Transformation Procedures

    SciTech Connect

    Timmins, S.

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  13. Walker-A Motif Acts to Coordinate ATP Hydrolysis with Motor Output in Viral DNA Packaging.

    PubMed

    delToro, Damian; Ortiz, David; Ordyan, Mariam; Sippy, Jean; Oh, Choon-Seok; Keller, Nicholas; Feiss, Michael; Catalano, Carlos E; Smith, Douglas E

    2016-07-01

    During the assembly of many viruses, a powerful ATP-driven motor translocates DNA into a preformed procapsid. A Walker-A "P-loop" motif is proposed to coordinate ATP binding and hydrolysis with DNA translocation. We use genetic, biochemical, and biophysical techniques to survey the roles of P-loop residues in bacteriophage lambda motor function. We identify 55 point mutations that reduce virus yield to below detectable levels in a highly sensitive genetic complementation assay and 33 that cause varying reductions in yield. Most changes in the predicted conserved residues K76, R79, G81, and S83 produce no detectable yield. Biochemical analyses show that R79A and S83A mutant proteins fold, assemble, and display genome maturation activity similar to wild-type (WT) but exhibit little ATPase or DNA packaging activity. Kinetic DNA cleavage and ATPase measurements implicate R79 in motor ring assembly on DNA, supporting recent structural models that locate the P-loop at the interface between motor subunits. Single-molecule measurements detect no translocation for K76A and K76R, while G81A and S83A exhibit strong impairments, consistent with their predicted roles in ATP binding. We identify eight residue changes spanning A78-K84 that yield impaired translocation phenotypes and show that Walker-A residues play important roles in determining motor velocity, pausing, and processivity. The efficiency of initiation of packaging correlates strongly with motor velocity. Frequent pausing and slipping caused by changes A78V and R79K suggest that these residues are important for ATP alignment and coupling of ATP binding to DNA gripping. Our findings support recent structural models implicating the P-loop arginine in ATP hydrolysis and mechanochemical coupling. PMID:27139643

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. 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

  16. The eastward shift of the Walker Circulation in response to global warming and its relationship to ENSO variability

    NASA Astrophysics Data System (ADS)

    Bayr, Tobias; Dommenget, Dietmar; Martin, Thomas; Power, Scott B.

    2014-11-01

    This study investigates the global warming response of the Walker Circulation and the other zonal circulation cells (represented by the zonal stream function), in CMIP3 and CMIP5 climate models. The changes in the mean state are presented as well as the changes in the modes of variability. The mean zonal circulation weakens in the multi model ensembles nearly everywhere along the equator under both the RCP4.5 and SRES A1B scenarios. Over the Pacific the Walker Circulation also shows a significant eastward shift. These changes in the mean circulation are very similar to the leading mode of interannual variability in the tropical zonal circulation cells, which is dominated by El Niño Southern Oscillation variability. During an El Niño event the circulation weakens and the rising branch over the Maritime Continent shifts to the east in comparison to neutral conditions (vice versa for a La Niña event). Two-thirds of the global warming forced trend of the Walker Circulation can be explained by a long-term trend in this interannual variability pattern, i.e. a shift towards more El Niño-like conditions in the multi-model mean under global warming. Further, interannual variability in the zonal circulation exhibits an asymmetry between El Niño and La Niña events. El Niño anomalies are located more to the east compared with La Niña anomalies. Consistent with this asymmetry we find a shift to the east of the dominant mode of variability of zonal stream function under global warming. All these results vary among the individual models, but the multi model ensembles of CMIP3 and CMIP5 show in nearly all aspects very similar results, which underline the robustness of these results. The observed data (ERA Interim reanalysis) from 1979 to 2012 shows a westward shift and strengthening of the Walker Circulation. This is opposite to what the results in the CMIP models reveal. However, 75 % of the trend of the Walker Circulation can again be explained by a shift of the dominant

  17. The Eastward Shift of the Walker Circulation in response to Global Warming and its relationship to ENSO variability

    NASA Astrophysics Data System (ADS)

    Bayr, Tobias; Dommenget, Dietmar

    2014-05-01

    This stduy investigates the global warming response of the Walker Circulation and the other zonal circulation cells (represented by the zonal stream function) in a CMIP5 multi-model ensemble (MMEns) under the RCP4.5 scenario. The changes in the mean state are presented as well as the changes in the modes of variability. The mean zonal circulation weakens nearly everywhere along the equator. Over the Pacific the Walker cell also shows a significant eastward shift. These changes in the mean circulation are very similar to the leading mode of interannual variability in the tropical zonal circulation cells, which is dominated by ENSO variability. During an El Nino event the circulation weakens and the rising branch over the Maritime Continent shifts to the east in comparison to neutral conditions (vice versa for a La Nina event). Two thirds of the global warming forced trend of the Walker cell can be explained by a long-term trend in this interannual variability pattern, i.e. a shift towards more El Nino-like conditions in the multi-model mean under global warming. In interannual variability the zonal circulation exhibits an asymmetry between El Nino and La Nina events. El Nino anomalies are located more to the east compared to La Nina anomalies. Consistent with this asymmetry we find a shift to the east of the dominant mode of variability of zonal stream function under global warming. All these results vary among the individual models, but the MMEns of CMIP3 and CMIP5 show in nearly all aspects very similar results, which underline the robustness of these results. The observed data (ERA Interim reanalysis) from 1979 to 2012 shows a westward shift and strengthening of the Walker Circulation. This is opposite to what the results in the CMIP models reveal. However, 75% of the trend of the Walker Cell can again be explained by a shift of the dominant mode of variability, but here towards more La Nina-like conditions. Thus long-term trends of the Walker cell seem to follow

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

    NASA Astrophysics Data System (ADS)

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

    1989-11-01

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

  19. 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

  20. Walker-Type Mean Circulations and Convectively Coupled Tropical Waves as an Interacting System.

    NASA Astrophysics Data System (ADS)

    Yano, Jun-Ichi; Moncrieff, Mitchell W.; Grabowski, Wojciech W.

    2002-05-01

    Interactions between convectively coupled tropical waves and Walker-type mean circulations are examined using a two-dimensional analytic model wherein drying and cooling of the boundary layer by convective and mesoscale downdrafts are in equilibrium with the wind-induced perturbations of surface fluxes. The moist thermodynamic state directly affects the stability of the large-scale circulation by controlling the wind perturbation on surface fluxes and the strength of the convective downdrafts. Stability analyses yield two major conclusions.(i) The mean Walker circulation is linearly unstable, suggesting that it may only exist in a quasi-steady sense through the spontaneous generation of transient waves. The instability is a manifestation of positive feedback: enhanced low-level convergence increases the surface wind speed, which increases the surface flux. As a result, convective heating is increased, which further enhances the low-level convergence. The mean circulation is more unstable when its horizontal extent is small and its depth large. Hence, when the horizontal extent of the mean circulation is a few thousand kilometers, as in the authors' recent cloud-resolving simulations, the deep first-baroclinic mode circulation is too unstable to be maintained even in a quasi-steady sense, realizing a shallow double-cell structure.(ii) The convectively coupled large-scale wave differs from traditional tropical large-scale instabilities of a homogeneous mean state in an important way: the longest waves are the most unstable rather than the shortest. Linear coupling of the waves with the mean state, through wind-induced surface flux perturbations, induces monotonically growing instabilities when the ascent of the mean circulation occupies more than half of the total domain. These instabilities occur only with the odd-wavenumber modes, which have parity with the mean circulation. Otherwise, the system supports linear neutral waves that propagate slower than the dry

  1. TIMING, EXTENT, AND SPATIAL PROGRESSION OF NEOGENE DISPLACEMENT TRANSFER, SOUTHERN WALKER LANE, WESTERN GREAT BASIN

    NASA Astrophysics Data System (ADS)

    Geissman, J. W.; Oldow, J. S.; Stockli, D. F.; Grow, J. S.

    2009-12-01

    Displacement transfer through structural stepovers linking misaligned segments of large-magnitude intracontinental transcurrent faults involve components of translational and rotational displacement and strain accommodated by complex three-dimensional arrays of structures. Although vertical-axis rotation of large spatial domains is well documented in many structural stepovers, the degree to which rotation is accommodated by rigid block and/or by distributed strain is not adequately resolved. Similarly, it is seldom established whether or to what degree translational and rotational deformation occur simultaneously over broad regions or if they are parts of a tectonic process involving different components of translational and rotational deformation occurring in spatially and temporally discrete domains. Our current understanding suggests that the displacement transfer system linking faults of the northern Eastern California Shear Zone and central Walker Lane during the mid-Miocene through the mid-Pliocene involves the development of three detachment fault systems underlying a NW-SE trending region stretching from the region east of Death Valley to beyond the northern end of the White Mountains and encompassing southern Walker Lane in Nevada. Integrated geologic mapping, paleomagnetic, thermochronologic ((U-Th)/HE), and structural analysis provides insight into the history and kinematics of transcurrent, high-angle normal faulting and slip on low-angle detachment faults and their relation to differential rotation of upper-plate, and locally lower-plate, rocks. Two extensional systems (Funeral - Bullfrog - Bare Mountain and Silver Peak - Lone Mountain) broadly share an inception age but the age of the third (Gold Mountain) is unknown. The extensional complexes apparently show a progressive decrease in the age at which exhumation ceased from SE to NW, over a duration of about 5 Ma. In contrast, the magnitude of clockwise rotation of upper-plate, and locally of lower

  2. 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

  3. A signal amplification electrochemical aptasensor for the detection of breast cancer cell via free-running DNA walker.

    PubMed

    Cai, Shuxian; Chen, Mei; Liu, Mengmeng; He, Wenhui; Liu, Zhijing; Wu, Dongzhi; Xia, Yaokun; Yang, Huanghao; Chen, Jinghua

    2016-11-15

    Herein, a signal magnification electrochemical aptasensor for the detection of breast cancer cell via free-running DNA walker is constructed. Theoretically, just one DNA walker, released by target cell-responsive reaction, can automatically cleave all D-RNA (a chimeric DNA/RNA oligonucleotide with a cleavage point rArU) anchored on electrode into shorter produces, giving rise to considerably detectable signal finally. Under the optimal conditions, the electrochemical signal decreased linearly with the concentration of MCF-7 cell. The linear range is from 0 to 500 cells mL(-1) with a detection limit of 47 cellsmL(-1). In a word, this approach may have advantages over traditional reported DNA machines for bioassay, particularly in terms of ease of operation, cost efficiency, free of labeling and of complex track design, which may hold great potential for wide application. PMID:27176917

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

    PubMed Central

    Møoller, U.; Bojsen, J.

    1976-01-01

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

  5. A review of the genera Acathrito Lyneborg, Phycus Walker and Salentia Costa (Diptera: Therevidae: Phycinae) from Egypt.

    PubMed

    Badrawy, Haitham B M

    2013-01-01

    The Egyptian fauna of the three genera Acathrito Lyneborg, Phycus Walker and Salentia Costa of subfamily Phycinae (Therevidae) is revised. Five species are recognized, three species of Phycus (including Phycus rufofemoratus Kröber as a new record) and one species for each of Acathrito and Salentia. A key to Egyptian Phycus species is included. Illustrations, specimens examined and distributions are given for each species. PMID:26097961

  6. 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.

  7. 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.

  8. Class of solutions of the Wheeler-DeWitt equation in the Friedmann-Robertson-Walker universe

    NASA Astrophysics Data System (ADS)

    Vieira, H. S.; Bezerra, V. B.

    2016-07-01

    We show that the solutions of the Wheeler-DeWitt equation in a homogeneous and isotropic universe are given by triconfluent Heun functions for the spatially closed, flat, and open geometries of the Friedmann-Robertson-Walker universe filled with different forms of energy. In a matter-dominated universe, we find the polynomial solution and the energy density spectrum. In the cases of radiation-dominated and vacuum universes, there are no polynomial solutions as shown.

  9. Taxonomic study of the genus Thisizima Walker, 1864 in China, with descriptions of two new species (Lepidoptera, Tineidae)

    PubMed Central

    Yang, Linlin; Li, Houhun; Kendrick, Roger C.

    2012-01-01

    Abstract The taxonomic study of the genus Thisizima Walker, 1864 is carried out in China. Thisizima subceratella sp. n. and Thisizima fasciaria sp. n. are described as new based on the specimens collected in Fujian, Hainan and Hong Kong. Detailed male and female genitalia are described for the first time for the genus. Photographs of adults and genital structures are provided. A checklist of all the described species is included. PMID:23378819

  10. Revision of the genus Ortopla Walker, [1859] with description of two new species from Southeast Asia (Lepidoptera, Noctuidae, Pantheinae). Revision of Pantheinae, contribution X.

    PubMed

    Behounek, G; Han, H L; Kononenko, V S

    2013-01-01

    The pantheine genus Ortopla Walker, [1859] 1858 is revised. Two new species, Ortopla witti sp. n. from the Philippines and O. longiuncus sp. n. from Nepal, Vietnam, Thailand, Myanmar and South China are described. The name O. commutanda Warren, 1891 (syn. n.) is synonymised with O. iarbasalis Walker, [1859] 1858. The distribution of species in East Asia is clarified. A checklist of the genus Ortopla is presented. Imagines, male and female genitalia of all species are illustrated. PMID:25113477

  11. Shrinkage activates a nonselective conductance: involvement of a Walker-motif protein and PKC.

    PubMed

    Nelson, D J; Tien, X Y; Xie, W; Brasitus, T A; Kaetzel, M A; Dedman, J R

    1996-01-01

    The ability of all cells to maintain their volume during an osmotic challenge is dependent on the regulated movement of salt and water across the plasma membrane. We demonstrate the phosphorylation-dependent gating of a nonselective conductance in Caco-2 cells during cellular shrinkage. Intracellular application of exogenous purified rat brain protein kinase C (PKC) resulted in the activation of a current similar to that activated during shrinkage with a Na(+)-to-Cl- permeability ratio of approximately 1.7:1. To prevent possible PKC- and/or shrinkage-dependent activation of cystic fibrosis transmembrane regulator (CFTR), which is expressed at high levels in Caco-2 cells, a functional anti-peptide antibody, anti-CFTR505-511, was introduced into the cells via the patch pipette. Anti-CFTR505-511, which is directed against the Walker motif in the first nucleotide binding fold of CFTR, prevented the PKC/shrink-age current activation. The peptide CFTR505-511 also induced current inhibition, suggesting the possible involvement of a regulatory element in close proximity to the channel that shares sequence homology with the first nucleotide binding fold of CFTR and whose binding to the channel is required for channel gating. PMID:8772443

  12. 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.

  13. Mutations in PIEZO2 Cause Gordon Syndrome, Marden-Walker Syndrome, and Distal Arthrogryposis Type 5

    PubMed Central

    McMillin, Margaret J.; Beck, Anita E.; Chong, Jessica X.; Shively, Kathryn M.; Buckingham, Kati J.; Gildersleeve, Heidi I.S.; Aracena, Mariana I.; Aylsworth, Arthur S.; Bitoun, Pierre; Carey, John C.; Clericuzio, Carol L.; Crow, Yanick J.; Curry, Cynthia J.; Devriendt, Koenraad; Everman, David B.; Fryer, Alan; Gibson, Kate; Giovannucci Uzielli, Maria Luisa; Graham, John M.; Hall, Judith G.; Hecht, Jacqueline T.; Heidenreich, Randall A.; Hurst, Jane A.; Irani, Sarosh; Krapels, Ingrid P.C.; Leroy, Jules G.; Mowat, David; Plant, Gordon T.; Robertson, Stephen P.; Schorry, Elizabeth K.; Scott, Richard H.; Seaver, Laurie H.; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, Sehime G.; Weaver, David D.; Whiteford, Margo; Williams, Marc S.; Tabor, Holly K.; Smith, Joshua D.; Shendure, Jay; Nickerson, Deborah A.; Bamshad, Michael J.

    2014-01-01

    Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher’s exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition. PMID:24726473

  14. Electrodynamics in the Friedmann Robertson Walker universe: Maxwell and Dirac fields in Newman Penrose formalism

    NASA Astrophysics Data System (ADS)

    Khanal, U.

    2006-07-01

    Maxwell and Dirac fields in Friedmann Robertson Walker (FRW) spacetime are investigated using the Newman Penrose method. The variables are all separable, with the angular dependence given by 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 dependences; 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 a 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.

  15. 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.

  16. 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.

  17. Development and Leaf Consumption by Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) Reared on Leaves of Agroenergy Crops.

    PubMed

    Cabezas, M F; Nava, D E; Geissler, L O; Melo, M; Garcia, M S; Krüger, R

    2013-12-01

    Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) is a polyphagous pest that threatens more than 24 species of crop plants including those used for biodiesel production such as Ricinus communis (castor bean), Jatropha curcas (Barbados nut), and Aleurites fordii (tung oil tree). The development and leaf consumption by S. cosmioides reared on leaves of these three species were studied under controlled laboratory conditions. The egg-to-adult development time of S. cosmioides was shortest when reared on castor bean leaves and longest when reared on tung oil tree leaves. Larvae reared on castor bean and Barbados nut leaves had seven instars, whereas those reared on tung oil tree leaves had eight. Females originating from larvae reared on castor bean and Barbados nut leaves showed greater fecundity than did females originating from larvae reared on tung oil tree leaves. Insects fed on castor bean leaves had shorter life spans than those fed on tung oil tree and Barbados nut leaves although the oviposition period did not differ significantly. The intrinsic and finite rates of increase were highest for females reared on castor bean leaves. Total leaf consumption was highest for larvae reared on tung oil tree leaves and lowest for those reared on Barbados nut leaves. We conclude that castor bean is a more appropriate host plant for the development of S. cosmioides than are Barbados nut and tung oil tree. PMID:27193276

  18. [Spectral features analysis of Pinus massoniana with pest of Dendrolimus punctatus Walker and levels detection].

    PubMed

    Xu, Zhang-Hua; Liu, Jian; Yu, Kun-Yong; Gong, Cong-Hong; Xie, Wan-Jun; Tang, Meng-Ya; Lai, Ri-Wen; Li, Zeng-Lu

    2013-02-01

    Taking 51 field measured hyperspectral data with different pest levels in Yanping, Fujian Province as objects, the spectral reflectance and first derivative features of 4 levels of healthy, mild, moderate and severe insect pest were analyzed. On the basis of 7 detecting parameters construction, the pest level detecting models were built. The results showed that (1) the spectral reflectance of Pinus massoniana with pests were significantly lower than that of healthy state, and the higher the pest level, the lower the reflectance; (2) with the increase in pest level, the spectral reflectance curves' "green peak" and "red valley" of Pinus massoniana gradually disappeared, and the red edge was leveleds (3) the pest led to spectral "green peak" red shift, red edge position blue shift, but the changes in "red valley" and near-infrared position were complicated; (4) CARI, RES, REA and REDVI were highly relevant to pest levels, and the correlations between REP, RERVI, RENDVI and pest level were weak; (5) the multiple linear regression model with the variables of the 7 detection parameters could effectively detect the pest levels of Dendrolimus punctatus Walker, with both the estimation rate and accuracy above 0.85. PMID:23697126

  19. 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±3.9 kbp. 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 181 h at a dose of 1×10(6)OBs/ml and 167 h 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

  20. 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 α-dystroglycan (α-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

  1. Preserving information from the beginning to the end of time in a Robertson-Walker spacetime

    NASA Astrophysics Data System (ADS)

    Mancini, Stefano; Pierini, Roberto; Wilde, Mark M.

    2014-12-01

    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.

  2. Synopsis of the 6th Walker's Cay Colloquium on Cancer Vaccines and Immunotherapy

    PubMed Central

    Kast, W Martin; Levitsky, Hyam; Marincola, Francesco M

    2004-01-01

    The 6th annual Cancer Vaccines and Immunotherapy Colloquium at Walker's Cay was held under the auspices of the Albert B. Sabin Vaccine Institute on March 10–13, 2004. The Colloquium consisted of a select group of 34 scientists representing academia, biotechnology and pharmaceutical industry. The main goal of this gathering was to promote in a peaceful and comfortable environment exchanges between basic and clinical science. The secondary benefit was to inspire novel bench to bedside ventures and at the same time provide feed back about promising and/or disappointing clinical results that could help re-frame some scientific question or guide the design of future trials. Several topics were covered that included tumor antigen discovery and validation, platforms for vaccine development, tolerance, immune suppression and tumor escape mechanisms, adoptive T cell therapy and dendritic cell-based therapies, clinical trials and assessment of response. Here we report salient points raised by speakers or by the audience during animated discussion that followed each individual presentation. PMID:15212694

  3. [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

  4. The Walker 256 Breast Cancer Cell- Induced Bone Pain Model in Rats

    PubMed Central

    Shenoy, Priyank A.; Kuo, Andy; Vetter, Irina; Smith, Maree T.

    2016-01-01

    The majority of patients with terminal breast cancer show signs of bone metastasis, the most common cause of pain in cancer. Clinically available drug treatment options for the relief of cancer-associated bone pain are limited due to either inadequate pain relief and/or dose-limiting side-effects. One of the major hurdles in understanding the mechanism by which breast cancer causes pain after metastasis to the bones is the lack of suitable preclinical models. Until the late twentieth century, all animal models of cancer induced bone pain involved systemic injection of cancer cells into animals, which caused severe deterioration of animal health due to widespread metastasis. In this mini-review we have discussed details of a recently developed and highly efficient preclinical model of breast cancer induced bone pain: Walker 256 cancer cell- induced bone pain in rats. The model involves direct localized injection of cancer cells into a single tibia in rats, which avoids widespread metastasis of cancer cells and hence animals maintain good health throughout the experimental period. This model closely mimics the human pathophysiology of breast cancer induced bone pain and has great potential to aid in the process of drug discovery for treating this intractable pain condition.

  5. Physical basis for the symmetries in the Friedmann-Robertson-Walker metric

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    2016-08-01

    Modern cosmological theory is based on the Friedmann-Robertson-Walker (FRW) metric. Often written in terms of co-moving coordinates, this well-known solution to Einstein's equations owes its elegant and highly practical formulation to the cosmological principle and Weyl's postulate, upon which it is founded. However, there is physics behind such symmetries, and not all of it has yet been recognized. In this paper, we derive the FRW metric coefficients from the general form of the spherically symmetric line element and demonstrate that, because the co-moving frame also happens to be in free fall, the symmetries in FRW are valid only for a medium with zero active mass. In other words, the spacetime of a perfect fluid in cosmology may be correctly written as FRW only when its equation of state is ρ+3 p = 0, in terms of the total pressure p and total energy density ρ. There is now compelling observational support for this conclusion, including the Alcock-Paczýnski test, which shows that only an FRW cosmology with zero active mass is consistent with the latest model-independent baryon acoustic oscillation data.

  6. 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

  7. 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

  8. Geophysical characterization of transtensional fault systems in the Eastern California Shear Zone-Walker Lane Belt

    NASA Astrophysics Data System (ADS)

    McGuire, M.; Keranen, K. M.; Stockli, D. F.; Feldman, J. D.; Keller, G. R.

    2011-12-01

    The Eastern California Shear Zone (ECSZ) and Walker Lane belt (WL) accommodate ~25% of plate motion between the North American and Pacific plates. Faults within the Mina deflection link the ECSZ and the WL, transferring strain from the Owens Valley and Death Valley-Fish Lake Valley fault systems to the transcurrent faults of the central Walker Lane. During the mid to late Miocene the majority of strain between these systems was transferred through the Silver Peak-Lone Mountain (SPLM) extensional complex via a shallowly dipping detachment. Strain transfer has since primarily migrated north to the Mina Deflection; however, high-angle faults bounding sedimentary basins and discrepancies between geodetic and geologic models indicate that the SPLM complex may still actively transfer a portion of the strain from the ECSZ to the WL on a younger set of faults. Establishing the pattern and amount of active strain transfer within the SPLM region is required for a full accounting of strain accommodation, and provides insight into strain partitioning at the basin scale within a broader transtensional zone. To map the active structures in and near Clayton Valley, within the SPLM region, we collected seismic reflection and refraction profiles and a dense grid of gravity readings that were merged with existing gravity data. The primary goals were to determine the geometry of the high-angle fault system, the amount and sense of offset along each fault set, connectivity of the faults, and the relationship of these faults to the Miocene detachment. Seismic reflection profiles imaged the high-angle basin-bounding normal faults and the detachment in both the footwall and hanging wall. The extensional basin is ~1 km deep, with a steep southeastern boundary, a gentle slope to the northwest, and a sharp boundary on the northwest side, suggestive of another fault system. Two subparallel dip-slip faults bound the southeast (deeper) basin margin with a large lateral velocity change (from ~2

  9. 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

  10. Changes in aboveground biomass and nutrient content on Walker Branch Watershed from 1967 to 1983

    SciTech Connect

    Johnson, D.W.; Henderson, G.S.; Harris, W.F.

    1987-01-01

    The increment of forest biomass and nutrient content on Walker Branch Watershed, Tennessee, from 1967 to 1983 was interrupted by two insect outbreaks. An outbreak of the southern pine beetle in the early 1970s and an outbreak of the hickory borer in the late 1970s to early 1980s killed a number of shortleaf pine (Pinus echinata) and hickory (Carya spp.), respectively. Yellow-poplar (Liriodendron tulipifera) growth increased over this 16-year period, especially in response to the mortality of shortleaf pine. The net result of these events was little change in total biomass but a substantial shift in species composition (from pine to yellow-poplar) in the Pine forest type over this period. No species has yet responded to the mortality of hickory. Due to the shift in species composition in the Pine type, calcium and magnesium accumulation rates in biomass increased but foliage biomass decreased over the inventory period. There was little change in foliage biomass or nutrient content in other forest types, despite hickory mortality, since mortality occurred primarily among large trees having low foliage-to-woody-biomass ratios. The insect attacks, combined with apparently natural self-thinning, caused a large increase in standing dead biomass and in nutrient return via tree fall. This increased rate of return will substantially alter forest floor nutrient content and availability, especially with regard to calcium (where the calcium content of standing dead currently equals forest floor calcium content) and nitrogen (where inputs of woody litter will substantially alter carbon to nitrogen ratios). 23 refs., 7 figs., 2 tabs.

  11. Neonatal carnitine palmitoyltransferase II deficiency associated with Dandy-Walker syndrome and sudden death.

    PubMed

    Yahyaoui, Raquel; Espinosa, María Gracia; Gómez, Celia; Dayaldasani, Anita; Rueda, Inmaculada; Roldán, Ana; Ugarte, Magdalena; Lastra, Gonzalo; Pérez, Vidal

    2011-11-01

    Neonatal onset of carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive, often lethal disorder of the mitochondrial beta-oxidation of long-chain fatty acids. It is a rare multiorgan disease which includes hypoketotic hypoglycemia, severe hepatomuscular symptoms, cardiac abnormalities, seizures and lethargy, as well as dysmorphic features. Until now, only 22 affected families have been described in the literature. An increasing number of mutations are being identified in the CPT2 gene, with a distinct genotype-phenotype correlation in most cases. Herein we report a new case of neonatal CPT II deficiency associated with Dandy-Walker syndrome and sudden death at 13 days of life. CPT II deficiency was suggested by acylcarnitine analysis of dried-blood on filter paper in the expanded newborn screening. Genetic analysis of the CPT2 gene identified the presence of a previously described mutation in homozygosity (c.534_558del25bpinsT). All lethal neonatal CPT II deficiency patients previously described presented severe symptoms during the first week of life, although this was not the case in our patient, who remained stable and without apparent vital risk during the first 11 days of life. The introduction of tandem mass spectrometry to newborn screening has substantially improved our ability to detect metabolic diseases in the newborn period. This case illustrates the value of expanded newborn screening in a neonate with an unusual clinical presentation, combining hydrocephalus and sudden death, that might not commonly lead to the suspicion of an inborn error of metabolism. PMID:21641254

  12. 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 η is a simple power a(η) = (1/η){sup n}, the stress-energy tensor obeys P = Øρ 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.

  13. Twenty-year changes in biomass and nutrient distribution in forests of Walker Branch Watershed, Tennessee

    SciTech Connect

    Johnson, D.W.; Olson, R.J.; Mann, L.K.; Todd, D.E.

    1988-01-01

    Changes in biomass and nutrient distribution in forests of Walker Branch Watershed from 1967 to 1987 are reviewed. There have been major changes in species composition in certain forest types: yellow-poplar (Liriodendron tulipifera) has largely been replaced by shortleaf pine (Pinus echinata) in what was formerly the pine forest type, and chestnut oak (Quercus prinus) appears to be replacing hickory in the oak-hickory forest type. In both cases, insect attacks (bark beetles and borers) precipitated the changes by inducing heavy mortality in native pines and hickory species in the 1970s. Subsoil (Bt horizon) exchangeable Ca/sup 2 +/ and Mg/sup 2 +/ have decreased markedly over a period of only 11 years in certain poor, upper-slope stands with oak and oak-hickory vegetation. From nutrient flux and mass balance analyses, we conclude that the Ca/sup 2 +/ changes can be attributed primarily to the sequestering of calcium in biomass. The situation with respect to Mg/sup 2 +/ is less clear; leaching was low relative to uptake in the one plot where Mg/sup 2 +/ decreases were statistically significant (95% level, t-test), yet it was clearly the dominant mechanism of Mg/sup 2 +/ export in all other plots where less significant (85% level, t-test) decreases were noted. It is noteworthy that leaching is dominated by SO/sub 4//sup 2/minus//, implying that acid deposition may be a major cause of the subsoil exchangeable Mg/sup 2 +/ decreases in some cases. 31 refs., 11 figs., 3 tabs.

  14. Cenozoic strike-slip faults in the northern Wassuk Range, Walker Lane

    SciTech Connect

    Dilles, J.H. . Geosciences Dept.)

    1993-04-01

    The N. Wassuk Ra. yields estimates of right-lateral Cenozoic strain in a portion of the northwest-trending Walker Lane, which has a total estimated right-lateral strain of 48--60 km (Ekren et al., 1984). The net right-lateral strain is < 10 km within an east-west 50 km-long segment extending from the N. Wassuk Ra. west to the Pine Nut Mts on the basis of continuous Jurassic plutonic units: Yerington batholith and quartz monzodiorite porphyry dikes. One of two dikes in the N. Wassuk Ra. may correlate easterly to Gillis Ra., suggesting [approximately]10 or 25 km right-lateral offset (Diles and R. Hardyman, unpub). In the N. Wassuk Ra. there are several ages of northwesterly striking faults. The oldest are [approximately]N45[degree]W striking, steeply dipping faults including the White Mt. and Wassuk Spur faults that step left to the northwest. Associated moderately dipping faults have tilted Oligocene tuffs to the W or SW to the SW of the fault zone, and both E and W on the NW; based on offset of the Jurassic porphyry dike and slickensides, these faults were dominantly oblique-slip normal faults with WNW-ESE slip. No lateral offsets can be directly measured across the steeply dipping faults; however, they juxtapose different Mesozoic metamorphic rocks and different thicknesses of Oligocene ignimbrites, suggesting significant lateral offset. Bingler's (1978) proposal that the White Mt. fault had left-laterally offset the White Mt. granite (WMG) from granite of Black Mountain (BMG) is unreasonable because the BMG intrudes the Wassuk Range diorite and contain biotite aplites, whereas the WMG intrudes metavolcanic rocks and contains tourmaline-muscovite aplites.

  15. Effectiveness of Removable Walker Cast Versus Nonremovable Fiberglass Off-Bearing Cast in the Healing of Diabetic Plantar Foot Ulcer

    PubMed Central

    Faglia, Ezio; Caravaggi, Carlo; Clerici, Giacomo; Sganzaroli, Adriana; Curci, Vincenzo; Vailati, Wanda; Simonetti, Daniele; Sommalvico, Francesco

    2010-01-01

    OBJECTIVE To evaluate the efficacy of a removable cast walker compared with that of a nonremovable fiberglass off-bearing cast in the treatment of diabetic plantar foot ulcer. RESEARCH DESIGN AND METHODS Forty-five adult diabetic patients with nonischemic, noninfected neuropathic plantar ulcer were randomly assigned for treatment with a nonremovable fiberglass off-bearing cast (total contact cast [TCC] group) or walker cast (Stabil-D group). Treatment duration was 90 days. Percent reduction in ulcer surface area and total healing rates were evaluated after treatment. RESULTS A total of 48 patients were screened; however, 2 patients in the TCC group and 1 patient in the Stabil-D group did not complete the study and were considered dropouts. There were no significant differences in demographic and clinic characteristics of the 45 patients completing the study. Ulcer surface decreased from 1.41 to 0.21 cm2 (P < 0.001) in the TCC group and from 2.18 to 0.45 cm2 (P < 0.001) in the Stabil-D group, with no significant differences between groups (P = 0.722). Seventeen patients (73.9%) in the TCC group and 16 patients (72.7%) in the Stabil-D group achieved healing (P = 0.794). Average healing time was 35.3 ± 3.1 and 39.7 ± 4.2 days in the TCC and Stabil-D group, respectively (P = 0.708). CONCLUSIONS The Stabil-D cast walker, although removable, was equivalent in efficacy to the TCC in terms of ulcer size reduction and total healing rate. The easier use of Stabil-D may help increase the use of off-loading devices in the management of plantar neuropathic diabetic foot ulcers. PMID:20357377

  16. [Fragile X syndrome with Dandy-Walker variant: a clinical study of oral and written communicative manifestations].

    PubMed

    Lamônica, Dionísia Aparecida Cusin; Ferraz, Plínio Marcos Duarte Pinto; Ferreira, Amanda Tragueta; Prado, Lívia Maria do; Abramides, Dagma Venturini Marquez; Gejão, Mariana Germano

    2011-01-01

    The Fragile X syndrome is the most frequent cause of inherited intellectual disability. The Dandy-Walker variant is a specific constellation of neuroradiological findings. The present study reports oral and written communication findings in a 15-year-old boy with clinical and molecular diagnosis of Fragile X syndrome and neuroimaging findings consistent with Dandy-Walker variant. The speech-language pathology and audiology evaluation was carried out using the Communicative Behavior Observation, the Phonology assessment of the ABFW - Child Language Test, the Phonological Abilities Profile, the Test of School Performance, and the Illinois Test of Psycholinguistic Abilities. Stomatognathic system and hearing assessments were also performed. It was observed: phonological, semantic, pragmatic and morphosyntactic deficits in oral language; deficits in psycholinguistic abilities (auditory reception, verbal expression, combination of sounds, auditory and visual sequential memory, auditory closure, auditory and visual association); and morphological and functional alterations in the stomatognathic system. Difficulties in decoding the graphical symbols were observed in reading. In writing, the subject presented omissions, agglutinations and multiple representations with the predominant use of vowels, besides difficulties in visuo-spatial organization. In mathematics, in spite of the numeric recognition, the participant didn't accomplish arithmetic operations. No alterations were observed in the peripheral hearing evaluation. The constellation of behavioral, cognitive, linguistic and perceptual symptoms described for Fragile X syndrome, in addition to the structural central nervous alterations observed in the Dandy-Walker variant, caused outstanding interferences in the development of communicative abilities, in reading and writing learning, and in the individual's social integration. PMID:21829935

  17. 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

  18. Late Quaternary faulting in Clayton Valley, Nevada: Implications for distributed deformation in the eastern California shear zone-Walker Lane

    NASA Astrophysics Data System (ADS)

    Foy, T. A.; Lifton, Z. M.; Frankel, K. L.; Johnson, C.

    2010-12-01

    The Walker Lane is a key component of the Pacific-North America plate boundary. This transtensional region of right lateral strike-slip and normal faulting accommodates ~25% of the total relative motion between the Pacific and North American plates. Recent studies indicate a discrepancy between short- and long-term rates of right-lateral shear in the Walker Lane with geodetic measurements of ~9.3 mm/yr being more than double the late Pleistocene geologic rate of <3.5 mm/yr. The Walker Lane, therefore, provides an excellent natural laboratory in which to address one of the major unresolved questions in active tectonics: are rates of strain accumulation and release along active plate boundaries constant through space and time or are significant temporal and spatial variations common? The Clayton Valley fault system of the Silver Peak-Lone Mountain extensional complex (SPLM) is a prime candidate to account for part of the “missing” strain in the Walker Lane due to its dominantly down-to-the-NW orientation, which ultimately accommodates right lateral shear in the region. The distribution of late Quaternary faults and alluvial fan deposits in Clayton Valley was determined through detailed geologic mapping (1:10,000 scale), which resulted in eight individual units that are consistent with the well-established western U.S. alluvial stratigraphy. Differential GPS was used to survey the prominent normal fault scarps displacing the fan deposits and cosmogenic nuclide (TCN) geochronology depth profile samples were collected from four units (Q2b, Q2c, Q2d, and Q3a). Displacement measured from the scarp profiles combined with TCN ages of the deformed fans will allow us to determine extension rates over multiple late Pleistocene time scales. Analysis of the Clayton Valley extension rates coupled with those from nearby structures, such as the Lone Mountain and Lida faults, will help determine if slip along these extensional faults can account for the observed discrepancy

  19. 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 −∞

  20. [Occurrence of accidents caused by Lonomia obliqua Walker, in the State of Paraná between 1989 and 2001].

    PubMed

    Garcia, Claudia Moreira; Danni-Oliveira, Inês Moresco

    2007-01-01

    The present article aimed to show the distribution of accidents involving the caterpillar Lonomia obliqua, Walker, 1855, in the State of Paraná between 1989 and 2001. The data were obtained from the Environmental Health Department of Paraná. The information collected was mapped using the Arcview program, and maps of the seasonal occurrence of accidents were generated. This seasonality was correlated with the insects life cycle and summer was shown to be the period with greatest incidence of accidents. The greatest concentrations occurred in the central-southern, southeastern and southwestern regions of the State. PMID:17568899

  1. 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.

  2. Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination

    NASA Astrophysics Data System (ADS)

    Giblin, John T.; Mertens, James B.; Starkman, Glenn D.

    2016-06-01

    While the use of numerical general relativity for modeling astrophysical phenomena and compact objects is commonplace, the application to cosmological scenarios is only just beginning. Here, we examine the expansion of a spacetime using the Baumgarte-Shapiro-Shibata-Nakamura formalism of numerical relativity in synchronous gauge. This work represents the first numerical cosmological study that is fully relativistic, nonlinear, and without symmetry. The universe that emerges exhibits an average Friedmann-Lemaître-Robertson-Walker (FLRW) behavior; however, this universe also exhibits locally inhomogeneous expansion beyond that expected in linear perturbation theory around a FLRW background.

  3. On the initial value problem for the wave equation in Friedmann-Robertson-Walker space-times.

    PubMed

    Abbasi, Bilal; Craig, Walter

    2014-09-01

    The propagator W(t 0,t 1)(g,h) for the wave equation in a given space-time takes initial data (g(x),h(x)) on a Cauchy surface {(t,x) : t=t 0} and evaluates the solution (u(t 1,x),∂ t u(t 1,x)) at other times t 1. The Friedmann-Robertson-Walker space-times are defined for t 0,t 1>0, whereas for t 0→0, there is a metric singularity. There is a spherical means representation for the general solution of the wave equation with the Friedmann-Robertson-Walker background metric in the three spatial dimensional cases of curvature K=0 and K=-1 given by S. Klainerman and P. Sarnak. We derive from the expression of their representation three results about the wave propagator for the Cauchy problem in these space-times. First, we give an elementary proof of the sharp rate of time decay of solutions with compactly supported data. Second, we observe that the sharp Huygens principle is not satisfied by solutions, unlike in the case of three-dimensional Minkowski space-time (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 00 emanating from the space-time singularity at t=0. Under reflection t→-t, the Friedmann-Robertson-Walker metric gives a space-time metric for t<0 with a singular future at t=0, and the same solution formulae hold. We thus have constructed solutions u(t,x) of the wave equation in Friedmann-Robertson-Walker space-times which exist for all [Formula: see text] and [Formula: see text], where in conformally regularized coordinates, these solutions are continuous through the singularity t=0 of space-time, taking on specified data u(0,⋅)=g(⋅) at the singular time. PMID:25197255

  4. Departures from the Friedmann-Lemaitre-Robertston-Walker Cosmological Model in an Inhomogeneous Universe: A Numerical Examination.

    PubMed

    Giblin, John T; Mertens, James B; Starkman, Glenn D

    2016-06-24

    While the use of numerical general relativity for modeling astrophysical phenomena and compact objects is commonplace, the application to cosmological scenarios is only just beginning. Here, we examine the expansion of a spacetime using the Baumgarte-Shapiro-Shibata-Nakamura formalism of numerical relativity in synchronous gauge. This work represents the first numerical cosmological study that is fully relativistic, nonlinear, and without symmetry. The universe that emerges exhibits an average Friedmann-Lemaître-Robertson-Walker (FLRW) behavior; however, this universe also exhibits locally inhomogeneous expansion beyond that expected in linear perturbation theory around a FLRW background. PMID:27391710

  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

  6. 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

  7. 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

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

    PubMed Central

    Lu, Ting; Shen, Tongye; Zong, Chenghang; Hasty, Jeff; Wolynes, Peter G.

    2006-01-01

    Cellular signal transduction often involves a reaction network of phosphorylation and transport events arranged with a ladder topology. If we keep track of the location of the phosphate groups describing an abstract state space, a simple model of signal transduction involving enzymes can be mapped on to a problem of how multiple biased random walkers compete to reach their target in the nucleus yielding a signal. Here, the first passage time probability and the survival probability for multiple walkers can be used to characterize the response of the network. The statistics of the first passage through the network has an asymmetric distribution with a long tail arising from the hierarchical structure of the network. This distribution implies a significant difference between the mean and the most probable signal transduction time. The response patterns for various external inputs generated by our model agree with recent experiments. In addition, the model predicts that there is an optimal phosphorylation enzyme concentration for rapid signal transduction. PMID:17071742

  9. 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.

  10. 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.

  11. Diagnosis of Van den Ende-Gupta syndrome: Approach to the Marden-Walker-like spectrum of disorders.

    PubMed

    Niederhoffer, Karen Y; Fahiminiya, Somayyeh; Eydoux, Patrice; Mawson, John; Nishimura, Gen; Jerome-Majewska, Loydie A; Patel, Millan S

    2016-09-01

    Marden-Walker syndrome is challenging to diagnose, as there is significant overlap with other multi-system congenital contracture syndromes including Beals congenital contractural arachnodactyly, D4ST1-Deficient Ehlers-Danlos syndrome (adducted thumb-clubfoot syndrome), Schwartz-Jampel syndrome, Freeman-Sheldon syndrome, Cerebro-oculo-facio-skeletal syndrome, and Van den Ende-Gupta syndrome. We discuss this differential diagnosis in the context of a boy from a consanguineous union with Van den Ende-Gupta syndrome, a diagnosis initially confused by the atypical presence of intellectual disability. SNP microarray and whole exome sequencing identified a homozygous frameshift mutation (p.L870V) in SCARF2 and predicted damaging mutations in several genes, most notably DGCR2 (p.P75L) and NCAM2 (p.S147G), both possible candidates for this child's intellectual disability. We review distinguishing features for each Marden-Walker-like syndrome and propose a clinical algorithm for diagnosis among this spectrum of disorders. © 2016 Wiley Periodicals, Inc. PMID:27375131

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

    PubMed

    Patnaik, Lalit; Umanand, Loganathan

    2015-12-01

    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 (v0) and step angle (φm) chosen for a given walk. In this paper, using basic mechanics, a framework of physical constraints that limit the choice of operating points is proposed. The constraint lines thus obtained delimit the allowable region of operation of the walker in the v0-φm plane. A given average forward velocity vx,avg can be achieved by several combinations of v0 and φm. Only one of these combinations results in the minimum mechanical power consumption and can be considered the optimum operating point for the given vx,avg. This paper proposes a method for obtaining this optimal operating point based on tangency of the power and velocity contours. Putting together all such operating points for various vx,avg, a family of optimum operating points, called the optimal locus, is obtained. For the energy loss and internal energy models chosen, the optimal locus obtained has a largely constant step angle with increasing speed but tapers off at non-dimensional speeds close to unity. PMID:26502096

  13. 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

  14. 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

  15. 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

  16. Creatine supplementation prevents hyperhomocysteinemia, oxidative stress and cancer-induced cachexia progression in Walker-256 tumor-bearing rats.

    PubMed

    Deminice, Rafael; Cella, Paola Sanches; Padilha, Camila S; Borges, Fernando H; da Silva, Lilian Eslaine Costa Mendes; Campos-Ferraz, Patrícia L; Jordao, Alceu Afonso; Robinson, Jason Lorne; Bertolo, Robert F; Cecchini, Rubens; Guarnier, Flávia Alessandra

    2016-08-01

    The purpose of this study was to investigate (1) the impact of tumor growth on homocysteine (Hcy) metabolism, liver oxidative stress and cancer cachexia and, (2) the potential benefits of creatine supplementation in Walker-256 tumor-bearing rats. Three experiments were conducted. First, rats were killed on days 5 (D5), 10 (D10) and 14 (D14) after tumor implantation. In experiment 2, rats were randomly assigned to three groups designated as control (C), tumor-bearing (T) and tumor-bearing supplemented with creatine (TCr). A life span experiment was conducted as the third experiment. Creatine was supplied in drinking water for 21 days (8 g/L) in all cases. Tumor implantation consisted of a suspension of Walker-256 cells (8.0 × 10(7) cells in 0.5 mL of PBS). The progressive increase (P < 0.05) in tumor mass coincided with a progressively lower body weight and higher hepatic oxidative stress; plasma Hcy concentration was 80 % higher (P < 0.05) by 10 days of tumor implantation. Impaired Hcy metabolism was evidenced by decreased hepatic betaine-homocysteine methyltransferase (Bhmt), glycine N-methyltransferase (Gnmt) and cystathionine beta synthase (CBS) gene expression. In contrast, creatine supplementation promoted a 28 % reduction of tumor weight (P < 0.05). Plasma Hcy (C 6.1 ± 0.6, T 10.3 ± 1.5, TCr 6.3 ± 0.9, µmol/L) and hepatic oxidative stress were lower in the TCr group compared to T. Creatine supplementation was unable to decrease Hcy concentration and to increase SAM/SAH ratio in tumor tissue. These data suggest that creatine effects on hepatic impaired Hcy metabolism promoted by tumor cell inoculation are responsible to decrease plasma Hcy in tumor-bearing rats. In conclusion, Walker-256 tumor growth is associated with progressive hyperhomocysteinemia, body weight loss and liver oxidative stress in rats. Creatine supplementation, however, prevented these tumor-associated perturbations. PMID:26781304

  17. 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...

  18. Determining thermotolerance of fifth-instar Cydia pomonella (L.) (Lepidoptera: Tortricidae) and Amyelois transitella (Walker) (Lepidoptera: Pyralidae) by three different methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thermotolerance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), were studied using two water immersion methods and one dry heat method. The two water immersion methods were: 1) directly immersing in hot w...

  19. Relative roles of differential SST warming, uniform SST warming and land surface warming in determining the Walker circulation changes under global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Li, Tim

    2016-04-01

    Most of CMIP5 models projected a weakened Walker circulation in tropical Pacific, but what causes such change is still an open question. By conducting idealized numerical simulations separating the effects of the spatially uniform sea surface temperature (SST) warming, extra land surface warming and differential SST warming, we demonstrate that the weakening of the Walker circulation is attributed to the western North Pacific (WNP) monsoon and South America land effects. The effect of the uniform SST warming is through so-called "richest-get-richer" mechanism. In response to a uniform surface warming, the WNP monsoon is enhanced by competing moisture with other large-scale convective branches. The strengthened WNP monsoon further induces surface westerlies in the equatorial western-central Pacific, weakening the Walker circulation. The increase of the greenhouse gases leads to a larger land surface warming than ocean surface. As a result, a greater thermal contrast occurs between American Continent and equatorial Pacific. The so-induced zonal pressure gradient anomaly forces low-level westerly anomalies over the equatorial eastern Pacific and weakens the Walker circulation. The differential SST warming also plays a role in driving low-level westerly anomalies over tropical Pacific. But such an effect involves a positive air-sea feedback that amplifies the weakening of both east-west SST gradient and Pacific trade winds.

  20. 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 ...

  1. Peace Education: Perspectives from Brazil and India. An Interview with Anima Bose (India) and Zlmarian Jeanne Walker (Brazil). Reprints and Miniprints No. 683.

    ERIC Educational Resources Information Center

    Bjerstedt, Ake

    As a means of studying ways to help children and young people deal constructively with questions of peace and war, Anima Bose and Zlmarian Jeanne Walker, who have worked to promote peace education in India and Brazil respectively, are interviewed. The influence of Gandhi on the concept of peace in India is emphasized. One cannot teach peace, it…

  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. 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...

  4. 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.

  5. The influence of ocean surface temperature gradient and continentality on the Walker circulation. II - Prescribed global changes

    NASA Technical Reports Server (NTRS)

    Stone, P. H.; Chervin, R. M.

    1984-01-01

    The series of experiments presently used to investigate the mechanisms responsible for forcing the global Walker circulation features worldwide changes in ocean surface temperatures (OSTs), topography, and/or continents. The primary factor affecting circulation is noted to be the global distribution of continents and oceans; while OST gradients are also important, topography emerges as comparatively unimportant. Continentality and OST gradients force the model atmosphere through the introduction of zonal variations in surface heating. The vertical motions to which they give rise yield moisture convergence and condensation variations which reinforce vertical motions. The forcing by OST gradients is partly nonlocal, and the atmospheric response is effected by continentality. In all cases, vertical motion zonal variations correlate with precipitation.

  6. The impact of ozone fumigations on the biology of a late season sugar maple defoliator (Heterocampa guttivitta Walker)

    SciTech Connect

    Constantin, M.; Mauffette, Y. )

    1993-06-01

    Two-year old sugar maple seedlings were exposed to charcoal-filtered air (CFA) and to three multiples (1x, 1.5x or 3x) of the ambient ozone (O[sub 3]) concentrations during the summers of 1991 and 1992. The saddled prominent (Heterocampa guttivitta Walker) was reared on leaves sampled from CFA and fumigated plants. Developmental cues such as pupal weight, survival rate, egg production and larval developmental time were measured and compared among CFA and 0, treatments. In 1991, larvae reared on the CFA foliage developed significantly lighter pupal weights than those reared on 1x and 3x (306mg vs 355mg and 353mg); the other variables were not affected by the treatments. A similar trend was observed in 1992 although pupal weights did not significantly differ among CFA and O[sub 3] fumigations. These results indicate that this lepidopteran can respond to biochemical changes induced by abiotic stresses such as ozone.

  7. Magnetic Resonance Imaging Diagnosis of Dandy-Walker-Like Syndrome in a Wire-Haired Miniature Dachshund

    PubMed Central

    KOBATAKE, Yui; MIYABAYASHI, Takayoshi; YADA, Naoko; KACHI, Shingo; OHTA, George; SAKAI, Hiroki; MAEDA, Sadatoshi; KAMISHINA, Hiroaki

    2013-01-01

    ABSTRACT A 12-week-old female Wire-haired miniature dachshund presented with non-progressive ataxia and hypermetria. Due to the animal’s clinical history and symptoms, cerebellar malformations were suspected. Computed tomography (CT) and magnetic resonance imaging (MRI) detected bilateral ventriculomegaly, dorsal displacement of the cerebellar tentorium, a defect in the cerebellar tentorium and a large fluid-filled cystic structure that occupied the regions where the cerebellar vermis and occipital lobes are normally located. The abovementioned cystic structure and the defect in the cerebellar tentorium were comparable to those seen in humans with Dandy-Walker syndrome. However, the presence of the cystic structure in the occipital lobe region was unique to the present case. During necropsy, the MRI findings were confirmed, but the etiology of the condition was not determined. PMID:23719692

  8. 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.

  9. 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.

  10. Interstitial deletion of 8q21{yields}22 associated with minor anomalies, congenital heart defect, and Dandy-Walker variant

    SciTech Connect

    Donahue, M.L.; Ryan, R.M.

    1995-03-13

    We describe an infant with a deletion of 8q21{yields}22 who had distinct clinical manifestations including minor facial anomalies, a congenital heart defect, a Dandy-Walker variant, and mild to moderate developmental delay. Her facial characteristics included small, wide-spaced eyes, asymmetric bilateral epicanthal folds, a broad nasal bridge, a {open_quotes}carp-shaped{close_quotes} mouth, micrognathia, and prominent, apparently low-set ears. Three other reports describe children with larger proximal deletions of 8q that include 8q21 and q22. These four children all have similar facial appearance. Of the others reported, one had a congenital heart defect and one had craniosynostosis. This case, in addition to the previously noted three cases, helps in delineating a recognizable syndrome. 12 refs., 3 figs., 1 tab.

  11. Ecology and demographics of hantavirus infections in rodent populations in the Walker River Basin of Nevada and California.

    PubMed

    Boone, J D; Otteson, E W; McGwire, K C; Villard, P; Rowe, J E; St Jeor, S C

    1998-09-01

    To study the ecologic correlates of hantavirus in deer mice (Peromyscus maniculatus), we sampled 114 sites in the Walker River Basin of Nevada and California in 1995-1996. Blood samples were tested for antibody to hantavirus, and a subset of samples was also tested for virus RNA by reverse transcription-polymerase chain reaction. Average prevalence of antibody-positive mice was 17%, with heavier males the most likely to be infected. Antibody prevalence varied within repeatedly sampled sites from 0% to 50% over the course of several months, suggesting possible infection cycles. Although there was no linear correlation between deer mouse density and antibody prevalence on sample sites, more complex relationships between density and prevalence appeared likely. Specifically, infections were less likely where rodent densities were lower than a critical threshold value. However, above this value, density had no effect on prevalence. PMID:9749642

  12. New Insights into Strain Accumulation and Release in the Central and Northern Walker Lane, Pacific-North American Plate Boundary, California and Nevada, USA

    NASA Astrophysics Data System (ADS)

    Bormann, Jayne M.

    The Walker Lane is a 100 km-wide distributed zone of complex transtensional faulting that flanks the eastern margin of the Sierra Nevada. Up to 25% of the total Pacific-North American relative right-lateral plate boundary deformation is accommodated east of the Sierra Nevada, primarily in the Walker Lane. The results of three studies in the Central and Northern Walker Lane offer new insights into how constantly accumulating plate boundary shear strain is released on faults in the Walker Lane and regional earthquake hazards. This research is based on the collection and analysis of new of geologic and geodetic datasets. Two studies are located in the Central Walker Lane, where plate boundary deformation is accommodated on northwest trending right-lateral faults, east-northeast trending left-lateral faults, and north trending normal faults. In this region, a prominent set of left-stepping, en-echelon, normal fault-bounded basins between Walker Lake and Lake Tahoe fill a gap in Walker Lane strike slip faults. Determining how these basins accommodate shear strain is a primary goal of this research. Paleoseismic and neotectonic observations from the Wassuk Range fault zone in the Walker Lake basin record evidence for at least 3 Holocene surface rupturing earthquakes and Holocene/late Pleistocene vertical slip rates between 0.4-0.7 mm/yr on the normal fault, but record no evidence of right-lateral slip along the rangefront fault. A complementary study presents new GPS velocity data that measures present-day deformation across the Central Walker Lane and infers fault slip and block rotation rates using an elastic block model. The model results show a clear partitioning between distinct zones of strain accommodation characterized by (1) right-lateral translation of blocks on northwest trending faults, (2) left-lateral slip and clockwise block rotations between east and northeast trending faults, and (3) right-lateral oblique normal slip with minor clockwise block rotations

  13. Present-Day Rates of Deformation Across the Southern Walker Lane From a Densified Regional GPS Network

    NASA Astrophysics Data System (ADS)

    Lifton, Z. M.; Frankel, K. L.; Newman, A. V.; Foy, T. A.; Feng, L.; Johnson, C.; Dixon, T. H.

    2010-12-01

    The Walker Lane is a diffuse region of right-lateral shear in western Nevada and eastern California that accommodates ~25% (9.3 ± 0.2 mm/yr) of the relative motion between the Pacific and North American plates. The region is characterized by discontinuous NNW-trending right-lateral strike-slip faults, and NE-trending, down-to-the-NW normal faults. The late Quaternary cumulative slip across the southern Walker Lane is only 1/3 the observed regional geodetic rate of right-lateral shear. We address this discrepancy between geologic and modern geodetic rates by installing and surveying a denser network of GPS monuments than previously existed. The higher spatial resolution will allow us to better define deformation rates in this complex tectonic setting. Our GPS data will be combined with accompanying fault kinematic and geochronologic data to determine deformation rates across multiple time scales, from late Quaternary to the present. We conducted a campaign GPS survey covering approximately 10,000 square kilometers encompassing the White Mountains, Fish Lake Valley, Clayton Valley, and the Silver Peak Range. We occupied 23 sites, including 10 newly installed monuments, which are spaced approximately 15-20 km apart. The existing sites used in this survey include the UNR-NEARNET sites, as well as a number of other campaign networks archived at UNAVCO. Stations with the longest history (including sites first surveyed as early as 1992) are expected to yield the most accurate results, while newer sites will help identify spatial patterns of strain partitioning. Monuments will be reoccupied annually and combined with past campaign survey data to determine modern crustal velocities. Initial results from this survey will be presented, which have important implications for understanding strain distribution along this important segment of the Pacific-North America boundary.

  14. Latest Quaternary paleoseismology and evidence of distributed dextral shear along the Mohawk Valley fault zone, northern Walker Lane, California

    NASA Astrophysics Data System (ADS)

    Gold, Ryan D.; Briggs, Richard W.; Personius, Stephen F.; Crone, Anthony J.; Mahan, Shannon A.; Angster, Stephen J.

    2014-06-01

    The dextral-slip Mohawk Valley fault zone (MVFZ) strikes northwestward along the eastern margin of the Sierra Nevada in the northern Walker Lane. Geodetic block modeling indicates that the MVFZ may accommodate ~3 mm/yr of regional dextral strain, implying that it is the highest slip-rate strike-slip fault in the region; however, only limited geologic data are available to constrain the system's slip rate and earthquake history. We mapped the MVFZ using airborne lidar data and field observations and identified a site near Sulphur Creek for paleoseismic investigation. At this site, oblique dextral-normal faulting on the steep valley margin has created a closed depression that floods annually during spring snowmelt to form an ephemeral pond. We excavated three fault-perpendicular trenches at the site and exposed pond sediment that interfingers with multiple colluvial packages eroded from the scarp that bounds the eastern side of the pond. We documented evidence for four surface-rupturing earthquakes on this strand of the MVFZ. OxCal modeling of radiocarbon and luminescence ages indicates that these earthquakes occurred at 14.0 ka, 12.8 ka, 5.7 ka, and 1.9 ka. The mean ~4 kyr recurrence interval is inconsistent with slip rates of ~3 mm/yr; these rates imply surface ruptures of more than 10 m per event, which is geologically implausible for the subdued geomorphic expression and 60 km length of the MVFZ. We propose that unidentified structures not yet incorporated into geodetic models may accommodate significant dextral shear across the northern Walker Lane, highlighting the role of distributed deformation in this region.

  15. 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

  16. 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

  17. 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

  18. Similar and Contrasting Response of Rifting and Transtension in the Gulf of California and Walker Lane to Preceding Arc Magmatism

    NASA Astrophysics Data System (ADS)

    Henry, C. D.; Faulds, J. E.

    2006-12-01

    The Gulf of California (GC) and Walker Lane (WL) have undergone strikingly similar development with strike- slip faulting following initial extension. They differ significantly in the amount of Pacific-North American plate motion taken up by each: essentially all relative motion in the GC and ~25% in the WL. In both areas, ancestral arc magmatism preceded and probably focused deformation, perhaps because heating and/or hydration weakened the lithosphere. However, differences in migration of the Rivera (RTJ) and Mendocino triple junctions (MTJ) related to differences in the orientation of plate boundaries determined how strike-slip faulting developed. Abrupt southward jumps in the RTJ led to abrupt cessation of magmatism over arc lengths of as much as 1000 km and initiation of east-northeast extension within the future GC. The best known jump was at ~13 Ma, but an earlier jump occurred at ~18 Ma. Arc magmatism has been best documented in Baja California, Sonora, and Nayarit, although Baja constituted the most-trenchward fringe of the ancestral arc. New and published data indicate that Sinaloa underwent a similar history of arc magmatism. The greatest volume of the arc immediately preceding RTJ jumps was probably in mainland Mexico. Arc magmatism shut off following these jumps, extension began in the future GC, and strike-slip faulting either followed or accompanied extension in the GC. In contrast, the MTJ migrated progressively northward. New and published data indicate magmatism generally shut off coincident with this retreat, but distinct nodes or zones of magmatism, presumably unrelated to subduction, persisted or initiated after arc activity ceased. We have suggested that the WL has grown progressively northward, following the retreating arc, and that the northern WL is its youngest part. However, the timing of initiation of strike-slip faulting in most of the WL is poorly known and controversial. Testing our hypothesis requires determining initiation and

  19. 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

  20. 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.

  1. On the taxonomy of the genera Proneca Swinhoe, 1890, Ctenane Swinhoe, 1905 and Selca Walker, 1866 (Lepidoptera, Nolidae, Nolinae), with the description of two new species from Sumatra.

    PubMed

    László, Gyula M; Ronkay, Gábor; Ronkay, László

    2015-01-01

    Present paper contains the characterisation of the genera Proneca Swinhoe, 1890, Ctenane Swinhoe, 1905, and Selca Walker, 1866, and their species, with the description of two new species, Proneca brunneostriata sp. n. and Ctenane         michaeli sp. n., from Sumatra. Two new combinations and a new synonymy are established. With 32 colour photos and 24 genitalia figures. PMID:26624747

  2. 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

  3. Histopathological effects and immunolocalization of periplocoside NW from Periploca sepium Bunge on the midgut epithelium of Mythimna separata Walker larvae.

    PubMed

    Feng, Mingxing; Shi, Baojun; Zhao, Yanchao; Hu, Zhaonong; Wu, Wenjun

    2014-10-01

    Periplocoside NW (PSNW) with pregnane glycoside skeleton is a novel insecticidal compound isolated from the root bark of Periploca sepium Bunge. This compound has a potent stomach poisoning activity against several insect pests. In this study, we observed the intoxication symptoms, investigated the histopathological effects and carried out immuno-electron microscopic localization of PSNW on the midgut epithelium of oriental armyworm Mythimna separata Walker larvae for better understanding its action mechanism against insects. Ultrastructural observations showed that cell damages caused by PSNW in the midgut of M. separata larvae are related to the degeneration of brush border microvilli. The dissolution of cytoskeletal structures in the interior and on the surface of microvilli was responsible for the decrease in size and eventual disappearance of microvilli when bubbles of cytoplasmic substances protrude into the midgut lumen of M. separata, thus resulting in cell death. The immuno-electron microscopic localization research showed that gold particle appeared on the microvilli layer of the midgut of M. separate larvae firstly. The density of gold particle gradually added with the time, and finally microvilli layer was destructed severely. Meantime, the gold particles were also presented to the intracellular organelle membrane and the organelles also were destructed. Therefore, we proposed that this membrane system on insect midgut epithelium cells is the initial acting site of PSNW against insects. PMID:25307468

  4. Competitive Interactions between Immature Stages of Bactrocera cucurbitae (Coquillett) and Bactrocera tau (Walker) (Diptera: Tephritidae) under Laboratory Conditions.

    PubMed

    Shen, K; Hu, J; Wu, B; An, K; Zhang, J; Liu, J; Zhang, R

    2014-08-01

    The melon fly, Bactrocera cucurbitae (Coquillett), and the pumpkin fly, Bactrocera tau (Walker), are economically important pests that attack mainly cucurbitacean fruits. The two fruit fly species have similar natural distributions, host ranges, and population growth capacities. This study was designed to assess the asymmetrical competitions through resource exploitation between the larvae of B. cucurbitae and B. tau at different density levels and temperatures, and on different hosts by comparing the relative effects of interspecific and intraspecific interactions on four life history parameters: survival rate, puparial mass, puparial duration, and developmental duration. Our results showed that intraspecific and interspecific competitions occurred under some laboratory conditions, and B. cucurbitae took advantage over B. tau at the high-density level and at low and high temperatures on pumpkin, bitter gourd, and bottle gourd when interspecific competition took place. Intraspecific and interspecific competitions mainly affected the puparial mass and the survival rate of the two fruit fly species but had no marked effect on the puparial duration or development duration. PMID:27193811

  5. Cloning, expression and purification of subunit H of vacuolar H⁺-ATPase from Mythimna separata Walker (Lepidoptera: Noctuidae).

    PubMed

    Lu, Lina; Qi, Zhijun; Wu, Wenjun

    2014-01-01

    The vacuolar (H+)-ATPase (V-ATPase) of insect, which is composed of membrane-bound V0 complex and peripheral V1 complex, participates in lots of important physiological process. Subunit H, as a subunit of V1 complex, plays a vital role in bridging the communication between V1 and V0 complexes and interaction with other proteins. Yeast subunit H has been successfully crystallized through expression in E. coli, but little is known about the structure of insect subunit H. In this study, we cloned, expressed and purified the subunit H from midgut of Mythimna separata Walker. Through RACE (rapidly amplification of cDNA ends) technique, we got 1807 bp full length of subunit H, and to keep the nature structure of subunit H, we constructed Baculovirus expression vector with His-tag in the C-terminal and expressed the recombinant protein in insect sf9 cells, thereafter, purified the recombinant protein by Ni-NTA columns. Results of SDS-PAGE, western blotting and mass spectrometry showed that the recombinant protein was successfully expressed. The method of expressing and purifying M. separata subunit H will provide a foundation for obtaining the crystal of subunit H and further study of the design of novel insecticides based on its structure and function. PMID:25257524

  6. 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.

  7. 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.

  8. Theory of the transmission of infection in the spread of epidemics: interacting random walkers with and without confinement.

    PubMed

    Kenkre, V M; Sugaya, S

    2014-12-01

    A theory of the spread of epidemics is formulated on the basis of pairwise interactions in a dilute system of random walkers (infected and susceptible animals) moving in [Formula: see text] dimensions. The motion of an animal pair is taken to obey a Smoluchowski equation in [Formula: see text]-dimensional space that combines diffusion with confinement of each animal to its particular home range. An additional (reaction) term that comes into play when the animals are in close proximity describes the process of infection. Analytic solutions are obtained, confirmed by numerical procedures, and shown to predict a surprising effect of confinement. The effect is that infection spread has a non-monotonic dependence on the diffusion constant and/or the extent of the attachment of the animals to the home ranges. Optimum values of these parameters exist for any given distance between the attractive centers. Any change from those values, involving faster/slower diffusion or shallower/steeper confinement, hinders the transmission of infection. A physical explanation is provided by the theory. Reduction to the simpler case of no home ranges is demonstrated. Effective infection rates are calculated, and it is shown how to use them in complex systems consisting of dense populations. PMID:25403272

  9. [Characterization of the damage of Spodoptera eridania (Cramer) and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) to structures of cotton plants].

    PubMed

    Santos, Karen B Dos; Meneguim, Ana M; Santos, Walter J Dos; Neves, Pedro M O J; Santos, Rachel B Dos

    2010-01-01

    The cotton plant, Gossypium hirsutum, hosts various pests that damage different structures. Among these pests, Spodoptera cosmioides (Walker) and Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae) are considered important. The objectives of this study were to characterize and to quantify the potential damage of S. eridania and S. cosmioides feeding on different structures of cotton plants. For this purpose, newly-hatched larvae were reared on the following plant parts: leaf and flower bud; leaf and boll; flower bud or boll; and leaf, flower bud and boll. The survival of S. cosmioides and S. eridania was greater than 80% and 70% for larvae fed on cotton plant parts offered separately or together, respectively. One larva of S. eridania damaged 1.7 flower buds, but did not damage bolls, while one larva of S. cosmioides damaged 5.2 flower buds and 3.0 cotton bolls. Spodoptera eridania and S. cosmioides can be considered species with potential to cause economic damage to cotton plants because they can occur throughout cotton developmental stages causing defoliation and losses of reproductive structures. Therefore, the results validate field observations that these two species of Spodoptera are potential pests for cotton. PMID:20878002

  10. Effects of Total Ginsenosides on the Feeding Behavior and Two Enzymes Activities of Mythimna separata (Walker) Larvae.

    PubMed

    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

  11. 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

  12. Chemical composition and antimicrobial and allelopathic activity of Tunisian Conyza sumatrensis (Retz.) E.WALKER essential oils.

    PubMed

    Mabrouk, Samia; Salah, Karima Bel Hadj; Elaissi, Ameur; Jlaiel, Lobna; Jannet, Hichem Ben; Aouni, Mahjoub; Harzallah-Skhiri, Fethia

    2013-02-01

    Conyza sumatrensis (Retz.) E.WALKER (Asteraceae) is a spontaneous annual herb, fairly widespread throughout Tunisia, which has rarely been studied or valued in any sector. Essential oils were obtained by hydrodistillation of different parts (flower heads, leaves, stems, and roots) of C. sumatrensis plants, which were collected in autumn (November 2007) at the flowering stage in the area of Monastir, Tunisia. In total, 98 compounds, representing 88.1-99.3% of the oil composition, were identified by GC-FID and GC/MS analyses. The root essential oil was distinguished by its high content in acetylenes (matricaria ester, 4; 74.3%), while those from flower heads and leaves were dominated by oxygenated sesquiterpenes (61.1 and 50.3%, resp.). The oils of C. sumatrensis from Tunisia belonged to a matricaria ester/caryophyllene oxide chemotype. All the oils were evaluated for antibacterial, antifungal, and allelopathic activities. The results indicate that the leaf oil exhibited significant in vitro antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, and Proteus mirabilis and that the C. sumatrensis oils isolated from the aerial parts presented high mycelia-growth inhibition of Candida albicans and the filamentous fungi tested. Moreover, the essential oils of the different plant parts inhibited the shoot and root growth of Raphanus sativus (radish) seedlings. Indeed, the inhibition of the hypocotyl growth varied from 28.6 to 90.1% and that of the radicle from 42.3 to 96.2%. PMID:23418168

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

    PubMed

    Räsänen, Syksy; Bolejko, Krzysztof; Finoguenov, Alexis

    2015-09-01

    We present a new test of the validity of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, based on comparing the distance from redshift 0 to z(1) and from z(1) to z(2) to the distance from 0 to z(2). If the Universe is described by the FLRW metric, the comparison provides a model-independent measurement of spatial curvature. The test relies on geometrical optics, it is independent of the matter content of the Universe and the applicability of the Einstein equation on cosmological scales. We apply the test to observations, using the Union2.1 compilation of supernova distances and Sloan Lens ACS Survey galaxy strong lensing data. The FLRW metric is consistent with the data, and the spatial curvature parameter is constrained to be -1.22<Ω(K0)<0.63, or -0.08<Ω(K0)<0.97 with a prior from the cosmic microwave background and the local Hubble constant, though modeling of the lenses is a source of significant systematic uncertainty. PMID:26382671

  14. Treatment of Walker ascites tumor cells by combination of photodynamic therapy with cyclophosphamide and interleukin-2 entrapped in liposomes

    NASA Astrophysics Data System (ADS)

    Dima, Vasile F.; Ionescu, Mircea D.; Balotescu, Carmen; Dima, V. S.

    2003-12-01

    The purpose of this study was to investigate the beneficial and adverse local effects of PDT associated with chemoimmunotherapy on rats bearing Walker ascites tumor cells. Experiments were performed on five batches of Wistar inbred rats with ascites tumor cells receiving intraperitoneally PDT (Photofrin II and 18 hrs later HeNe laser irradiation); Cyclophosphamide (CY); interleukin-2 (IL-2) or associated therapy (PDT+CY+IL-2). The control batch consisted of untreated rats (HBSS). The following results were noticed: (a) sole administration of PDT, IL-2 or CY reduced tumor growth, gave survival rates between 28.4 and 56.5% and cure rates ranging from 12.4 to 33.3%; (b) combined therapy (PDT+CY+IL-2) decreased tumor growth, increased survival rates (88.5%) and cure rates were 73.1% forty-two days post-transplantation. Summing up, in this study we noticed that PDT associated with chemoimmunotherapy reduced mortality as well as tumor volumes and increased cure rates in rats with ascites tumor cells. This approach points to the need for further evaluation in patients with peritoneal malignancies.

  15. Physical exercise and a leucine-rich diet modulate the muscle protein metabolism in Walker tumor-bearing rats.

    PubMed

    Salomão, Emilianne M; Toneto, Aline T; Silva, Gisele O; Gomes-Marcondes, Maria Cristina C

    2010-01-01

    Leucine-supplemented diet can recover lean body mass and preserve muscle protein mass. Additionally, physical exercise can be an excellent alternative to improve the rehabilitation of cancer patients. Knowing these facts, we examined the effects of a leucine-rich diet with or without physical aerobic exercise on muscle protein metabolism in Walker tumor-bearing rats. Young rats were divided into 4 groups that did or did not perform light aerobic exercise (swim training) and were on a leucine-rich diet or a control diet for 2 mo. After this time, these animals were implanted or not with tumors (subcutaneously) following groups for either control diet or leucine-rich diet fed rats: control, trained, tumor-bearing, and trained tumor-bearing. Twenty-one days after implantation, the tumor growth induced a decrease in the muscle protein synthesis and increased the catabolic process, which was associated with an increase in the expression of the ubiquitin-proteasome subunits (20S, 19S, and 11S). In contrast, the exercise program minimized the muscle degradation process and increased muscle myosin content. Additionally, leucine supplementation also modulated proteasome subunits, especially the 19S and 11S. In summary, the exercise has beneficial effects by reducing tumor growth, leading to an improvement in protein turnover especially when in conjunction with a leucine-rich diet. PMID:21058197

  16. Late Neogene slip transfer and extension within the curved Whisky Flat fault system central Walker Lane, west-central Nevada

    NASA Astrophysics Data System (ADS)

    Biholar, Alexander Kenneth Casian

    In Whisky Flat of west-central Nevada, northwest-striking faults in the Walker Lane curve to east-northeast orientations at the northern limits of the Mina deflection. This curve in strike results in the formation of ˜685 m deep depression bounded by north-south convex to the east range-front faults that at the apex of fault curvature are bisected at a high angle by a structural stepover. We use the vertical offset of a late Miocene erosional surface mapped in the highlands and inferred from gravity depth inversion in the basin to measure the magnitude of displacement on faults. A N65°W extensional axis determined through fault-slip inversion is used to constrain the direction in displacement models. Through the use of a forward rectilinear displacement model, we document that the complex array of faults is capable of developing with broadly contemporaneous displacements on all structures since the opening of the basin during the Pliocene.

  17. Effect of a high-intensity exercise training on the metabolism and function of macrophages and lymphocytes of walker 256 tumor bearing rats.

    PubMed

    Bacurau, Aline Villa Nova; Belmonte, Mônica Aparecida; Navarro, Francisco; Moraes, Milton Rocha; Pontes, Francisco Luciano; Pesquero, Jorge Luiz; Araújo, Ronaldo Carvalho; Bacurau, Reury Frank Pereira

    2007-11-01

    Epidemiologic studies suggest that moderately intense training promotes augmented immune function, whereas strenuous exercise can cause immunosupression. Because the combat of cancer requires high immune function, high-intensity exercise could negatively affect the host organism; however, despite the epidemiologic data, there is a lack of experimental evidence to show that high-intensity training is harmful to the immune system. Therefore, we tested the influence of high-intensity treadmill training (10 weeks, 5 days/week, 30 mins/day, 85% VO(2)max) on immune system function and tumor development in Walker 256 tumor-bearing Wistar rats. The metabolism of glucose and glutamine in lymphocytes and macrophages was assessed, in addition to some functional parameters such as hydrogen peroxide production, phagocytosis, and lymphocyte proliferative responses. The metabolism of Walker 256 cells was also investigated. Results demonstrated that high-intensity training increased the life span of tumor-bearing rats, promoted a reduction in tumor mass, and prevented indicators of cachexia. Several changes, such as a reduction in body weight and food intake and activation of glutamine metabolism in macrophages and lymphocytes induced by the presence of Walker 256 tumor, were prevented by high intensity training. The reduction in tumor growth was associated with an impairment of tumor cell glucose and glutamine metabolism. These data suggest that high-intensity exercise training may be a viable strategy against tumors. PMID:17959841

  18. Spatial and temporal variability in faulting along a Quaternary fault transect across the Northern Walker Lane, California-Nevada

    NASA Astrophysics Data System (ADS)

    Gold, R. D.; Briggs, R. W.; Crone, A. J.

    2013-12-01

    What are the temporal and spatial patterns of faulting across shear zones with overlapping parallel faults that are preferentially oriented to accommodate regional shear? How should earthquake hazard be modeled if these systems have variable earthquake recurrence? We explore these questions in the Northern Walker Lane, a 100-km-wide zone of dextral shear along the eastern side of the Sierra Nevada, which accommodates ~15% of the 50 mm/yr of relative motion between the Pacific and North American plates. We used high-resolution airborne Light Distance and Ranging (LiDAR) data to create surficial geologic maps, conducted paleoseismic trenching, applied Quaternary geochronology, and collected high-resolution seismic-reflection profiles along a fault-perpendicular transect across the principal, subparallel, northwest-striking Mohawk Valley, Grizzly Valley, Honey Lake, and Warm Springs Valley dextral-slip faults. Key results along this transect from southwest-to-northeast are: (1) trenching at the Sulphur Creek Sidehill Bench site on the Mohawk Valley fault system indicates four surface-rupturing earthquakes since ~14 ka, which is fewer events than inferred from the slip rate of 2.9 mm/yr from geodetic block-models. To reconcile these results, we suggest that strain is widely distributed on numerous uncharacterized fault strands or that the contemporary (geodetic block model) rate is a young phenomena and hasn't been sustained since 14 ka. (2) High-resolution shallow seismic-reflection imaging and topographic analysis using the LiDAR data provide the first conclusive evidence that the Grizzly Valley fault system is an active Quaternary structure, with probable motion in the latest Quaternary. This result is significant because this fault system is not presently included in the USGS Quaternary fault-and-fold database, is not specified as a seismic source in most regional hazard models, and is also not defined as a boundary in regional geodetic block models. (3) New

  19. Dose-Response Relationship of Physical Activity to Premature and Total All-Cause and Cardiovascular Disease Mortality in Walkers

    PubMed Central

    Williams, Paul T.

    2013-01-01

    Purpose To assess the dose-response relationships between cause-specific mortality and exercise energy expenditure in a prospective epidemiological cohort of walkers. Methods The sample consisted of the 8,436 male and 33,586 female participants of the National Walkers' Health Study. Walking energy expenditure was calculated in metabolic equivalents (METs, 1 MET = 3.5 ml O2/kg/min), which were used to divide the cohort into four exercise categories: category 1 (≤1.07 MET-hours/d), category 2 (1.07 to 1.8 MET-hours/d), category 3 (1.8 to 3.6 MET-hours/d), and category 4 (≥3.6 MET-hours/d). Competing risk regression analyses were use to calculate the risk of mortality for categories 2, 3 and 4 relative to category 1. Results 22.9% of the subjects were in category 1, 16.1% in category 2, 33.3% in category 3, and 27.7% in category 4. There were 2,448 deaths during the 9.6 average years of follow-up. Total mortality was 11.2% lower in category 2 (P = 0.04), 32.4% lower in category 3 (P<10−12) and 32.9% lower in category 4 (P = 10−11) than in category 1. For underlying causes of death, the respective risk reductions for categories 2, 3 and 4 were 23.6% (P = 0.008), 35.2% (P<10−5), and 34.9% (P = 0.0001) for cardiovascular disease mortality; 27.8% (P = 0.18), 20.6% (P = 0.07), and 31.4% (P = 0.009) for ischemic heart disease mortality; and 39.4% (P = 0.18), 63.8% (P = 0.005), and 90.6% (P = 0.002) for diabetes mortality when compared to category 1. For all related mortality (i.e., underlying and contributing causes of death combined), the respective risk reductions for categories 2, 3 and 4 were 18.7% (P = 0.22), 42.5% (P = 0.001), and 57.5% (P = 0.0001) for heart failure; 9.4% (P = 0.56), 44.3% (P = 0.0004), and 33.5% (P = 0.02) for hypertensive diseases; 11.5% (P = 0.38), 41.0% (P<10−4), and 35.5% (P = 0.001) for dysrhythmias: and 23.2% (P = 0.13), 45.8% (P = 0.0002), and 41

  20. CHARACTERIZATION OF TRYPSIN-LIKE AND CHYMOTRYPSIN-LIKE SERINE PROTEASES FROM MIDGUT OF Mythimna separata Walker.

    PubMed

    Zhou, Xiaoqun; Fan, Dong; Zhao, Kuijun

    2016-07-01

    Two cDNA sequences encoding a trypsin-like and a chymotrypsin-like serine protease (MsT and MsCT, GenBank accession Nos. KP730443 and KP730444, respectively) were cloned from midgut of oriental armyworm, Mythimna separata Walker. Multiple alignments revealed that the deduced amino acid sequences of MsT and MsCT contained a serine protease catalytic motif GDSGGPL and catalytic triads (His, Asp, and Ser). Analyses of tissue and developmental expression of MsT and MsCT showed that they were mainly expressed in midguts and could be detected in first to sixth instar larvae, prepupal and pupal stages. Expressions of both MsT and MsCT were downregulated after 24 h of starvation and upregulated by subsequent insect refeeding. MsT expression in response to 20-hydroxyecdysone (20E) was dose dependent and upregulated after 24 h. However, MsCT expression in response to 20E was downregulated compared with controls. MsCT, but not MsT, transcripts were upregulated after 24 h of Cry1Ac protoxin exposure. These results suggested that MsT was most likely involved in food protein digestion and molting in M. separata whereas MsCT was most likely involved in food protein digestion and Bacillus thuringiensis (Bt) protoxin activation. RNA interference indicated that MsT and MsCT expression levels decreased 76.7 and 86.2% after treated with MsT and MsCT dsRNA, respectively. This study showed that M. separata expressed midgut proteases in line with known lepidopteran counterparts and contributed valuable sequence resource information regarding insect proteases. PMID:26988941

  1. Enhancement of photodynamic therapy due to hyperbaric hyperoxia: an experimental study of Walker 256 tumors in rats

    NASA Astrophysics Data System (ADS)

    Nicola, Jorge H.; Colussi, Valdir C.; Nicola, Ester M. D.; Metze, Konradin

    1997-05-01

    Photodynamic therapy (PDT), which is now an approved treatment for many types of cancers, is based on the simultaneous involvement of three factors, namely: tumor tissue retention of a specific photosensitizer; local illumination of the lesion with a visible light source and the occurrence of oxygen in the triplet state. Theoretically, a change in any one of these factors may be compensated by a change in the other two factors, leading to the same therapeutic result. In practice, this is not true, since we are dealing with living tissue, but we may expect to find an ideal combination of these three factors which may give the best clinical results. In this work we present experimental results of PDT under Hyperbaric hyperoxia (HBO) in tumor masses of the dorsal subcutaneous tissue of rats. These tumors were created by previous inoculation of 'Walker 256' neoplastic cells Hematoporphyrin Ester (HpE) was administered as the photosensitizer. The rats were pressurized at up to 3 atm with a 100 percent continuous oxygen ventilation environment in a specially designed hyperbaric chamber. The skin area above the tumor was photosensitized for 45 minutes with a 7 mw HeNe laser. Twenty four hours later, the tumor was removed for study. In all the animals treated with PDT/HBO histology revealed a very important reduction in the number of tumor cells as compared with the PDT controls in normal atmospheric condition, showing numerous apoptotic as well as necrotic cells at the border of the radiated area. The observed enhancement in the PDT for this situation is, of course, related to the extra oxygen in the circulatory system.

  2. 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

  3. 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.

  4. Variation in foliar 15N abundance and the availability of soil nitrogen on Walker Branch Watershed

    SciTech Connect

    Garten Jr, Charles T

    1993-10-01

    Spatial patterns in natural {sup 15}N abundance ({sup o}{sup 15}N) in soil, soil solutions, and non-N{sub 2}-fixing plants were studied in the deciduous forest on Walker Branch Watershed near Oak Ridge, Tennessee. This study was undertaken to test the hypothesis that foliar {sup o}{sup 15}N values are related to the availability of inorganic nitrogen in mineral soil. Soils collected in or near valley bottoms on the watershed had higher levels of net nitrogen mineralization and net nitrification potential than those sampled from ridges and slopes. More positive foliar {sup o}{sup 15}N values occurred in valley bottoms, which, relative to other positions on the watershed, were characterized by greater availability of soil nitrogen and lower C-to-N ratios in the O{sub i}-horizon, in the surface mineral soil, and in autumn leaf fall. Although leaf nitrogen concentrations changed significantly over the course of the growing season, there was little seasonal variation in foliar {sup o}{sup 15}N values. A hypothesis about the relative importance of different sources of nitrogen to the forest and how nitrogen cycling varies with topography in this nitrogen-deficient ecosystem was derived, in part, from spatial patterns in natural {sup 15}N abundance. There appear to be two processes affecting the topographic patterns in foliar {sup 15}N abundance on this watershed: (1) greater uptake from isotopically heavy pools of inorganic soil nitrogen by plants in valley bottoms, and (2) uptake of isotopically light ammonium-N in atmospheric deposition by plants on ridges and slopes (where the availability of inorganic soil nitrogen to plant roots is more limited). Results from this study indicate that foliar {sup o}{sup 15}N values are positively correlated with net nitrification potential in surface soil.

  5. Variation in foliar [sup 15]N abundance and the availability of soil nitrogen on Walker Branch Watershed

    SciTech Connect

    Garten, C.T. Jr. )

    1993-10-01

    Spatial patterns in natural [sup 15]N abundance ([sigma][sup 15]N) in soil, soil solutions, and non-N[sub 2]-fixing plants were studied in the deciduous forest on Walker Branch Watershed near Oak Ridge, Tennessee. This study was undertaken to test the hypothesis that foliar [sigma][sup 15]N values are related to the availability of inorganic nitrogen in mineral soil. Soils collected in or near valley bottoms on the watershed had higher levels of net nitrogen mineralization and net nitrification potential than those sampled from ridges and slopes. More positive foliar [sigma][sup 15]N values occurred in valley bottoms, which, relative to other positions on the watershed, were characterized by greater availability of soil nitrogen and lower C-to-N ratios in the O[sub 1]-horizon, in the surface mineral soil, and in autumn leaf fall. Although leaf nitrogen concentrations changed significantly over the course of the growing season, there was little seasonal variation in foliar [sigma][sup 15]N values. A hypothesis about the relative importance of different sources of nitrogen to the forest and how nitrogen cycling varies with topography in this nitrogen-deficient ecosystem was derived, in part, from spatial patterns in natural [sup 15]N abundance. There appear to be two processes affecting the topographic patterns in foliar [sup 15]N abundance on this watershed: (1) greater uptake from isotopically heavy pools of inorganic soil nitrogen by plants in valley bottoms, and (2) uptake of isotopically light ammonium-N in atmospheric deposition by plants on ridges and slopes (where the availability of inorganic soil nitrogen to plant roots is more limited). Results from this study indicate that foliar [sigma][sup 15]N values are positively correlated with net nitrification potential in surface soil. 34 refs., 13 figs., 8 tabs.

  6. Mortality of Dandy-Walker syndrome in the United States: Analysis by race, gender, and insurance status

    PubMed Central

    McClelland, Shearwood; Ukwuoma, Onyinyechi I.; Lunos, Scott; Okuyemi, Kolawole S.

    2015-01-01

    Background: Dandy-Walker syndrome (DWS) is a congenital disorder often diagnosed in early childhood. Typically manifesting with signs/symptoms of increased intracranial pressure, DWS is catastrophic unless timely neurosurgical care can be administered via cerebrospinal fluid (CSF) drainage. The rates of mortality, adverse discharge disposition (ADD), and CSF drainage in DWS may not be uniform regardless of race, gender or insurance status; such differences could reflect disparities in access to neurosurgical care. This study examines these issues on a nationwide level. Materials and Methods: The Kids’ Inpatient Database spanning 1997-2003 was used for analysis. Only patients admitted for DWS (ICD-9-CM = 742.3) were included. Multivariate analysis was adjusted for several variables, including patient age, race, sex, admission type, primary payer, income, and hospital volume. Results: More than 14,000 DWS patients were included. Increasing age predicted reduced mortality (OR = 0.87; P < 0.05), ADD (OR = 0.96; P < 0.05), and decreased likelihood of receiving CSF drainage (OR = 0.86; P < 0.0001). Elective admission type predicted reduced mortality (OR = 0.29; P = 0.0008), ADD (OR = 0.68; P < 0.05), and increased CSF drainage (OR = 2.02; P < 0.0001). African-American race (OR = 1.20; P < 0.05) and private insurance (OR = 1.18; P < 0.05) each predicted increased likelihood of receiving CSF drainage, but were not predictors of mortality or ADD. Gender, income, and hospital volume were not significant predictors of DWS outcome. Conclusion: Increasing age and elective admissions each decrease mortality and ADD associated with DWS. African-American race and private insurance status increase access to CSF drainage. These findings contradict previous literature citing African-American race as a risk factor for mortality in DWS, and emphasize the role of private insurance in obtaining access to potentially lifesaving operative care. PMID:25883477

  7. Lidar-Based Mapping of Late Quaternary Faulting Along the Grizzly Valley Fault, Walker Lane Seismic Belt, California

    NASA Astrophysics Data System (ADS)

    Hitchcock, C. S.; Hoirup, D. F.; Barry, G.; Pearce, J.; Glick, F.

    2012-12-01

    The Grizzly Valley fault (GVF) is located within the northern Walker Lane, a zone of right-lateral shear between the Sierra Nevada and the Basin and Range in Plumas County. The GVF extends southeasterly from near Mt. Ingalls along the eastern side of Lake Davis. It may partially connect with the Hot Creek fault within Sierra Valley and extend south to Loyalton with an overall approximate length of 50 km. Comparison of high-resolution topography developed from LiDAR data with published bedrock geologic mapping documents the presence of geomorphic features that provide information on fault activity of the GVF. Field mapping verified tectonically deformed and offset late Quaternary surfaces identified on bare-earth LiDAR imagery across the GVF within glacial deposits on the eastern margin of Lake Davis, and alluvial deposits in Sierra Valley. Along the GVF, conspicuous geomorphic and hydrologic features include scarps in alluvial surfaces, elongated depressions aligned with adjacent linear escarpments, truncated bedrock spurs, closed depressions, linear swales, right-lateral deflections of creeks and river courses, and shutter ridges, as well as springs and linear seeps consistent with right-lateral strike-slip faulting. The discontinuous nature of observed fault traces combined with the apparent down-to-the-west offset of alluvial surfaces at the southern and northern ends of the eastern margin of Lake Davis are consistent with a broad bend or step over in the fault. Scarp profiles of apparently faulted surfaces extracted from LiDAR data document vertical offsets of up to 14 m. Our study suggest that the GVF is an oblique, right-lateral fault that has been active in the late Quaternary. This study complements on-going investigations by DWR to assess the impact of seismic hazards on State Water Project infrastructure.

  8. 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.

  9. 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.

  10. 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.

  11. Nitrogen-13 glutamate uptake and perfusion in Walker 256 carcinosarcoma before and after single-dose irradiation

    SciTech Connect

    Knapp, W.H.; Helus, F.; Layer, K.; Panzer, M.; Hoever, K.H.O.; Ostertag, H.

    1986-10-01

    Nitrogen-13 (13N) glutamate uptake was recorded in 18 anesthetized rats, both before and at least once after intervention. Each investigation was immediately followed by imaging of blood flow distribution using (11C)butanol. All animals had Walker 256 carcinosarcoma implants in one hind leg. Tumors were locally irradiated with a dose of 800 rad in 14 rats; in four rats, the vasoactive substance 5-hydroxytryptamine (5-HT) was administered. Prior to interventions, the (13N)glutamate tumor-to-muscle uptake showed a linear correlation with blood flow close to identity (y = 0.117 + 0.915x, r = 0.97). After irradiation, a discordant pattern was observed: blood flow tended to increase, while (13N)glutamate tumor-to-muscle uptake dropped from 4.30 +/- 0.66 (s.e.m.) to 3.06 +/- 0.36 (p less than 0.005) during 30 min and attained 4.04 +/- 0.67 2 days later. If (13N)glutamate tumor-to-muscle uptake was related to that of (11C) butanol in each individual animal, this index dropped from 0.93 +/- 0.03 (s.e.m.) to 0.62 +/- 0.04 (p less than 0.001) 30 min after irradiation and attained 0.90 +/- 0.09 after 2 days. In animals treated with 5-HT, (13N)glutamate and (11C)butanol showed a parallel drop from 6.60 +/- 0.84 to 2.10 +/- 0.60 (p less than 0.05) and from 6.8 +/- 0.78 to 2.08 +/- 0.74 (p less than 0.05), respectively. Thus, single-dose irradiation causes (13N)glutamate uptake to be uncoupled with respect to flow, while (13N)glutamate uptake in untreated tumors is flow-limited and responds together with flow on vasomotion.

  12. 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

  13. The colonization of carrion by soldier fly, Ptecticus melanurus (Walker) (Diptera: Stratiomyidae) in a tropical forest in Malaysia: a new potential species for minimum PMI estimation.

    PubMed

    Azwandi, A; Omar, B

    2012-12-01

    This paper discusses the colonization of the stratiomyid species Ptecticus melanurus (Walker) (Diptera: Stratiomyidae) in monkey carrion and its potential for the determination of the minimum time since death (PMI). A study was conducted in a tropical forest at Bangi, Malaysia from 13 November 2009 to 8 June 2011. Twelve monkey carcasses (Macaca fascicularis Raffles) were used and divided in equal number into three different field trials. Adults of P. melanurus were first observed on monkey carrions on the second day the carcasses were placed in the field while their penultimate instar larvae were found in the wet soil under and beside carcass from day 8 to 31 days postmortem. PMID:23202610

  14. Review of the world species of Spaniopus Walker, 1833 (Hymenoptera: Pteromalidae), with description of a new species from the Russian Far East.

    PubMed

    Tselikh, Ekaterina

    2015-01-01

    The species of Spaniopus Walker, 1833 (Pteromalidae) are reviewed. A new species from the Russian Far East, S. belokobylskiji sp. nov., is described and illustrated. Redescriptions and illustrations of all available types of Spaniopus species are provided. A key for the identification of the twelve known species of Spaniopus is given. Five species, Spaniopus fulvicornis Bouček, S. japonicus Kamijo, S. nigriceps Kamijo, S. sasacolae Kamijo and S. varicornis Bouček are recorded from Russia for the first time. PMID:26701506

  15. A revision of the genus Belciana Walker, 1862 with description of three new species (Lepidoptera, Noctuidae: Pantheinae) from East and South East Asia. Revision of Pantheinae, contribution XII.

    PubMed

    Behounek, G; Han, H L; Kononenko, V S

    2015-01-01

    The Oriental Pantheinae genus Belciana Walker, 1862 is revised. Three new species, B. hreblayi sp. n., B. sulawesiana sp. n., B. pinratanai sp. n., from Taiwan, Indonesia and Thailand, are described. Five new combinations in the genus Diphteroides Bethune-Baker, 1906 are proposed: Diphteroides caerulea (Hampson, 1926) comb. n., D. habroscia (Prout, 1924) comb. n., D. patricolor (Prout, 1924) comb. n., D. serrata Bethune-Baker, 1906, D. subserrata (Prout, 1924) comb. n. and D. sophronia (Prout, 1924) comb. n. The extensive diagnoses of known species of Belciana are given. The imagines, male and female genitalia are illustrated. The checklist of the genus Belciana in East Asia is presented. PMID:26624184

  16. Constraints from GPS on Block Kinematics of the Transition between the Southern Walker Lane and the Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Jha, S.; Hammond, W. C.; Kreemer, C.; Blewitt, G.

    2008-12-01

    The southern Walker Lane (SWL) is a part of the Eastern California Shear Zone that lies north of the Mojave region, bounded by the Garlock Fault to the south, the Sierra Nevada to the west, the Basin and Range to the east and by Mono Lake to the north. The region includes many northwest striking right-lateral strike slip and sub-parallel normal faults (e.g. Death Valley/Furnace Creek, Fish Lake Valley, Owens Valley), which together accommodate ~25% of the Pacific/North American relative motion. For many of these faults, and the system as a whole, there appears to be a discrepancy between geodetically and geologically inferred fault slip rates. Since the installation of the EarthScope Plate Boundary Observatory (PBO), and the Nevada Earthquake Response Network (NEARNET) of the University of Nevada, Reno, many recently obtained high- precision GPS data are now available to place improved constraints on the pattern and rates of crustal deformation of this region. In this study we use a block modeling methodology to estimate block motions and fault slip rates from GPS velocities of PBO, NEARNET and BARGEN continuous sites. Time series were obtained from raw RINEX data that we processed using the GIPSY-OASIS II software from the Jet Propulsion Laboratory together with the Ambizap software for ambiguity resolution. We have additionally included earlier published campaign-style velocities, in those areas where we do not have better coverage from other continuous/semi-continuous networks. Geologic slip rates have been obtained from the published literature. We solve for the motion of blocks using the GPS velocities that have been adjusted based on the viscoelastic modeling to estimate long term motion. To evaluate the consistency between the geologic and geodetic data, we compare long-term fault slip to slip rates inferred from geodetic results obtained over <10 years. We account for transient earthquake cycle effects by modeling the viscoelastic postseismic relaxation

  17. Immune and metabolic responses of Chilo suppressalis Walker (Lepidoptera: Crambidae) larvae to an insect growth regulator, hexaflumuron.

    PubMed

    Mirhaghparast, Seyyedeh Kimia; Zibaee, Arash; Sendi, Jalal Jalali; Hoda, Hassan; Fazeli-Dinan, Mahmoud

    2015-11-01

    Efficient control of Chilo suppressalis Walker is always controversial due to highly economic damage, resistance to insecticides and environmental pollutions. So, combination of safe pest controls e.g. biocontrol agents and insect growth regulators seems to be promising via integrated pest management program. Bioassay of hexaflumuron on 4th larval instars revealed concentrations of 44.34, 179.74 and 474.94µg/ml as LC10-50 values. Numbers of total hemocytes, plasmatocytes and granulocytes as well as phenoloxidase activity increased in the different time intervals following treatment by hexaflumuron. Combined effects of hexaflumuron and Beauveria bassiana Vuillemin also increased hemocyte numbers and phenoloxidase activity at different time intervals using all concentrations. Activities of general esterases assayed by α- and β-naphtyl acetate and glutathione S-transferase using CDNB and DCNB increased 1-12h post-treatment. Activities of aspartate aminotransferase, alanine aminotransferase, γ-glutamyl transferase and aldolase increased in the larvae treated by hexaflumuron. However enhanced activity of lactate dehydrogenase was only obtained by treating 180 and 470µg/ml concentrations of hexaflumuron. Activities of ACP and ALP were found to be higher than control for all time intervals even 1-12h post-treatment. The amounts of HDL and LDL increased in the highest concentrations of hexaflumuron after 12-24h of post-treatment. Amount of triglyceride was higher than that of control after 1 and 3h but it was lower in other time intervals. Amounts of glycogen and protein were lower than those of control for all time intervals except for 6 and 12h of post-treatment in case of protein. Results of the current study revealed negative effects of hexaflumuron on intermediary metabolism of Chilo suppressalis but it increased the number of hemocytes and activity of phenoloxidase which are responsible for spore removal from hemolymph. It can be concluded that hexaflumuron is

  18. Long-Term Data Reveal Patterns and Controls on Stream Water Chemistry in a Forested Stream: Walker Branch, Tennessee

    SciTech Connect

    Lutz, Brian D; Mulholland, Patrick J; Bernhardt, Emily

    2012-01-01

    We present 20 years of weekly stream water chemistry, hydrology, and climate data for the Walker Branch watershed in eastern Tennessee, USA. Since 1989, the watershed has experienced a similar to 1.08 degrees C increase in mean annual temperature, a similar to 20% decline in precipitation, and a similar to 30% increase in forest evapotranspiration rates. As a result, stream runoff has declined by similar to 34%. We evaluate long-term trends in stream water concentrations and fluxes for nine solutes and use wet deposition data to calculate approximate watershed input-output budgets. Dissolved constituents were classified as geochemical solutes (Ca2+, Mg2+, and SO42-) or nutrients (NH4+, NO3-, soluble reactive phosphorus [SRP], total soluble nitrogen [TSN], total soluble phosphorus [TSP], and dissolved organic carbon [DOC]). Geochemical solutes are predominantly controlled by discharge, and the long-term changes in catchment hydrology have led to significant trends in the concentrations and fluxes of these solutes. Further, the trends in geochemical solute concentrations indicate shifting soil flowpath contributions to streamflow generation through time, with deep groundwater having a greater proportional contribution in recent years. Despite dramatic changes in watershed runoff, there were no trends in inorganic nutrient concentrations (NH4+, NO3-, and SRP). While most nutrients entering the watershed are retained, stream fluxes of nutrient solutes have declined significantly as a result of decreasing runoff. Nutrient concentrations in the stream exhibit large seasonality controlled by in-stream biological uptake. Stream benthic communities are sensitive to hydrologic disturbance, and changes in the frequency or intensity of storm events through time can affect nutrient fluxes. Stream NO3- concentrations are also sensitive to drought, with concentrations decreasing (increasing) if conditions during the three years prior to the time of sampling were drier (wetter

  19. Using a walker

    MedlinePlus

    ... with your weak leg first. If you had surgery on both legs, start with the leg that feels weaker. Then step forward with your other leg, placing it in front of the weaker leg. Repeat steps 1 through 4 to move forward. Go ...

  20. Dandy-Walker Syndrome

    MedlinePlus

    ... The key features of this syndrome are an enlargement of the fourth ventricle (a small channel that ... early infancy, include slow motor development and progressive enlargement of the skull. In older children, symptoms of ...

  1. From precocious fame to mature obscurity: David Walker (1837-1917) MD, LRCSI, surgeon and naturalist to the Fox Arctic Expedition of 1857-59.

    PubMed

    Froggatt, Peter; Walker, Brian M

    2012-11-01

    The Belfast-born David Walker was the 19-year-old surgeon and naturalist on the epic Fox Arctic Expedition (1857-59) that established the fate of Sir John Franklin's unsuccessful (1845) search for the North-West Passage. On return the crew were fêted as heroes and decorated, and shared in a £5000 government bounty: Walker was also received by the Queen and (in Ireland) by the Lord Lieutenant, was honoured by the principal British and Irish natural history societies and his portrait was exhibited in the National Portrait Gallery, London. This paper describes his adventurous life, including the Fox Expedition, which from 1862 was spent abroad and included time in the Cariboo gold fields, service in the United States Army, practice in a notorious Californian frontier town and, in later life, the comparative quiet of general and occupational medical practice in Portland, Oregon. Once a household name, his death went unrecorded in the British and Irish medical and lay press. PMID:23143316

  2. Clustering of velocities in a GPS network spanning the Sierra Nevada Block, the northern Walker Lane Belt, and the Central Nevada Seismic Belt, California-Nevada

    USGS Publications Warehouse

    Savage, James C.; Simpson, Robert W.

    2013-01-01

    The deformation across the Sierra Nevada Block, the Walker Lane Belt, and the Central Nevada Seismic Belt (CNSB) between 38.5°N and 40.5°N has been analyzed by clustering GPS velocities to identify coherent blocks. Cluster analysis determines the number of clusters required and assigns the GPS stations to the proper clusters. The clusters are shown on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. Four significant clusters are identified. Those clusters are strips separated by (from west to east) the Mohawk Valley-Genoa fault system, the Pyramid Lake-Wassuk fault system, and the Central Nevada Seismic Belt. The strain rates within the westernmost three clusters approximate simple right-lateral shear (~13 nstrain/a) across vertical planes roughly parallel to the cluster boundaries. Clustering does not recognize the longitudinal segmentation of the Walker Lane Belt into domains dominated by either northwesterly trending, right-lateral faults or northeasterly trending, left-lateral faults.

  3. 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

    NASA Astrophysics Data System (ADS)

    Savage, J. C.; Simpson, R. W.

    2013-09-01

    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.

  4. GPR profiles of Saddle Mountain scoria deposits on Walker Lake Crater tuff ring in Arizona help understanding of geomorphological response to wildland fire

    NASA Astrophysics Data System (ADS)

    Martinez-Hackert, B.; Schwartz, C.; Williams, K.

    2009-05-01

    Walker Lake tuff ring in the San Francisco Volcanic Field, Arizona, experienced a significant forest fire in 1996. Extensive event scale studies suggested a highly increased (by two orders of magnitude) erosion rate both due to raindrop impact and overland flow. However, the 2.3 million year old cone's materials are partially covered by a 15,000-year-old scoria cone deposit from nearby Saddle Mountain. Although previous studies of the geomorphology of Walker Lake crater provided insight into the Saddle Mountain deposit, new studies have actually shown the extent and depth of the deposit on the cone. We present data obtained with ground penetrating radar (GPR) that gives a clearer data set on the depth (4-7m) of the younger deposit in one of the more extensively studied areas. Data were collected along longitudinal and horizontal profiles along the southwestern part of the cone where the deposit is clearly recognizable on the surface and the wild land fire devastation is enormous. Future analysis will shed quantitative light on the effect that the younger, less cohesive materials has on the increased erosion rates in the event scale to decadal scale erosion rates after wildland fire.

  5. Active deformation in the Northern Walker Lane: a detailed geodetic study of the Mohawk Valley and Honey Lake/Warm Springs fault systems

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The Mohawk Valley and Honey Lake/Warm Springs faults are parallel, northwest striking, dextral fault systems separated by ~50 km in the westernmost part of the Northern Walker Lane. These two faults work as a cooperative pair to accommodate 3-5 mm/yr of the total 8 mm/yr of right-lateral deformation geodetically observed across the Northern Walker Lane, however it is unclear with fault is dominant. Geologic studies of the faults result in right-lateral slip rates of 1-2.5 mm/yr on the Honey Lake fault and a minimum of 0.3 mm/yr on the Mohawk Valley fault. In contrast, previous geodetic studies estimate slip rates of ~1 mm/yr on the Honey Lake fault and ~3 mm/yr on the Mohawk Valley fault. To reconcile the discrepancy between the distribution of slip on the faults and the differences between sums of the geologically and geodetically estimated slip rates, we use new GPS data to constrain an elastic block model developed specifically to study the Mohawk Valley and Honey Lake/Warm Springs fault systems. We present a dense GPS velocity solution (~10 km average station spacing) that incorporates new data from the semi-continuous Mobile Array of GPS for Nevada Transtension network (MAGNET, http://geodesy.unr.edu/networks) operated by the University of Nevada, Reno with continuous data from the EarthScope Plate Boundary Observatory and other networks. Data collected during the summer of 2012 bring many MAGNET GPS time series in the Northern Walker Lane to near 5 years in duration. The density of our velocity field and recent advances in data processing give us unprecedented precision in the measurement of contemporary deformation in the Northern Walker Lane. We use the velocity solution to solve for slip rates on the companion fault systems and explore the effects of block model geometry assumptions and tradeoffs. Our model predicts slip rates of 2.2±0.3 mm/yr for the Mohawk Valley fault and 1.1±0.2 mm/yr for the Honey Lake fault. Block model slip rate estimates are

  6. 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.

  7. Evolution of the Walker Lane: An Incipient Transform Fault and Future Pacific-North America Plate Boundary

    NASA Astrophysics Data System (ADS)

    Faulds, J. E.; Henry, C. D.

    2009-12-01

    Since ~30 Ma, western North America has been evolving from an Andean type margin to a dextral transform. Transform growth has been marked by arc retreat, orogenic collapse, and inland steps of the San Andreas fault system (SAF). In the western Great Basin (WGB), a system of dextral faults, known as the Walker Lane (WL) in the north and eastern California shear zone (ECSZ) in the south, currently accommodates ~20% of the Pacific - North America dextral motion. In contrast to the continuous 1100-km-long SAF, discontinuous ~10-250-km-long dextral faults comprise the WL-ECSZ. Displacement across the WL-ECSZ decreases N-ward from ≥60 km in south to E-central California, to ~25 km in NW Nevada, to zero in NE California. Geodetic strain rates are ~10 mm/yr across the WL-ECSZ in the WGB but decrease to <2.5 mm/yr at the NW terminus in NE California. The evolution of the WL-ECSZ is closely linked to events along the SAF. The early Miocene elimination of microplates along the southern California coast, S-ward steps in the Rivera triple junction at 19-16 Ma and 13 Ma, and an increase in plate motions ~12 Ma induced the first major episode of deformation in the WL-ECSZ, which began ~13 Ma along the N60°W-trending Las Vegas shear zone (LVSZ). The LVSZ shear zone paralleled plate motions, formed inboard of where the SAF initially organized into a through-going structure, and accommodated ~60 km of right slip ~13 to 6 Ma. In the late Miocene, the southern part of the transform shifted (~13-6 Ma) east to the Gulf of California (GC), the Big Bend of the SAF developed, and plate motions changed from ~N60°W to N37°W (11-6 Ma). Coincidentally (~11-6 Ma), dextral shear shifted west in the WL-ECSZ from the LVSZ to a NNW belt in the WGB. Dextral shear was favored in the WGB as it paralleled the new plate motion, aligned with the GC, and avoided the Big Bend bottleneck. By ~4 Ma, dextral shear had propagated to the northern WL (NW Nevada - NE California) in concert with the N

  8. 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

  9. Exploring Western and Eastern Pacific contributions to the 21st century Walker circulation intensification and teleconnected precipitation declines (Invited)

    NASA Astrophysics Data System (ADS)

    Funk, C. C.; Hoerling, M. P.; Hoell, A.; Verdin, J. P.; Robertson, F. R.; Alured, D.; Liebmann, B.

    2013-12-01

    presented. These results suggest that a substantial component of the recent Walker circulation intensification has been related to the IWPWS. The IWPWS warming extends from just north of Papua New Guinea to just west of Hawaii, and appears associated with SLP, wind and rainfall responses consistent with enhanced Indo-Pacific convection. These decomposition results are compared with a set of numerical simulation experiments based on the ECHAM5 and GFS models forced with characteristic IWP and EP SST for 1983-1996 and 1999-2012. The talk concludes with a tentative discussion of the decadal predictability associated with the IWPWS. Using both observed and model-simulated precipitation, we briefly explore potential IWPWS drought teleconnection regions in the Americas, Asia, Middle East, and Eastern Africa. Figure 1. Western Pacific and Eastern Pacific SST changes between 1999-2012 and 1983-1996. Figure 2. Western Pacific and Eastern Pacific GPCP precipitation changes between 1999-2012 and 1983-1996.

  10. Rates and timing of vertical-axis block rotations across the Sierra Nevada-Walker Lane transition in the Bodie Hills

    NASA Astrophysics Data System (ADS)

    Rood, D. H.; Herman, S.; Burbank, D.; Bogue, S.

    2008-12-01

    We use paleomagnetic data from Tertiary volcanic rocks to address the rates and timing of vertical-axis block rotation across the Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada. In zones of continental deformation, block rotations are an important mechanism for permanent stain accommodation, and thus may be crucial to testing geodetic block models and resolving geologic-geodetic slip discrepancies. In our study, data included in the paleomagetic site means are high quality AF demagnetization results (least squared fits that generally include 5-7 points with MAD values less than 1). Thermal demagnetization results match the AF directions, and both thermal demag and rockmag results indicate strong ChRM, mostly carried by single domain magnetite. The site means used to calculate the VGPs all have a95 values less than 10 (mostly 2-5) and include 6-11 sites each. Each site (and thus site mean) has a reasonably well-known structural correction. The VGP scatter values range from 12 to 16 degrees, indicating that they include appropriate secular variation. The mean declinations and 95 percent confidence limits for each VGP timeslice are statistically distinct from one another (71 ± 9, 39 ± 13, and 11 ± 11 degrees). The slope of a linear regression fit to the age versus declination data gives a rate of vertical axis block rotation of approximately 3-4 degrees/Myr. Fitting two separate lines to the age vs. declination data would indicate an increase in the rates of rotation since ~10 Ma. Two possible interpretations of the data are: (1) the rotations began during or before the Middle Miocene, or (2) rates of rotation were high initially (e.g. ~10 Ma) and decelerated until the Pliocene. These data have implications for the (1) timing and spatial extent of distributed strain accumulation related to the initiation of the San Andreas Fault-Eastern California Shear Zone-Walker Lane transform plate boundary, (2) transfer of transform plate boundary

  11. 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

  12. A Plio-Pleistocene Synthesis of Tropical Planktonic Oxygen Isotope Records: Early Closure of the Isthmus of Panama and Late Development of the Walker Circulation

    NASA Astrophysics Data System (ADS)

    Wara, M. W.; Ravelo, A. C.; Ziegler, C. L.; Schilla, A. S.

    2001-12-01

    We present records from Ocean Drilling Program (ODP) Site 847 in the Eastern Equatorial Pacific (EEP) Ocean of oxygen (δ 18O) and carbon isotope measurements on the mixed layer dwelling planktonic foraminifera, Globogerinoides sacculifer (w/o sacc-like final chamber) and in the deep dwelling planktonic foraminifera Globoritalia tumida from 5 Ma to present. ODP Site 847 (0° N, 95° W, 3346 m water depth) is ideally located to record EEP conditions over this time interval because it is in the core of South Equatorial Current. A comparison of the ODP Site 847 G. sacculifer (w/o sacc) record with previously published planktonic foraminiferal δ 18O records from the western tropical Pacific (ODP Site 806), the eastern Indian Ocean (ODP Site 758) and the Caribbean Sea (ODP Site 999) indicates several major changes in tropical ocean circulation over the past 5 Ma. At 4.2 Ma significant changes in the δ 18O difference between the EEP (ODP Site 847) and the Caribbean (ODP Site 999) indicate that surface water exchange between the Atlantic and Pacific became restricted, or that there was a tropical climate reorganization that influenced surface salinity/temperature fields of both basins. Between 5 and 2 Ma, there is no gradient in δ 18O in the western (ODP Site 806) and eastern (ODP Site 847) tropical Pacific, indicative of a reduced or absent Walker circulation. After 2 Ma, the δ 18O gradient developed and then remained relatively constant during the past 1 Ma. At the same time as the gradient in the tropical Pacific developed, the difference between conditions in the eastern Indian Ocean (ODP site 758) and western tropical Pacific (ODP Site 806) was reduced. After 1 Ma, foraminifera at the two sites (806 and 758) had nearly identical δ 18O compositions. In sum, as the gradient between the eastern and western tropcial Pacific was established, the difference between the Indian and Pacific oceans was reduced. Thus, hydrographic gradients indicative of a modern vigorous

  13. 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...

  14. 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

  15. [Intravenous Sedation and Repeated "the Same Day General Anesthesia" for a School-age Boy with Dandy-Walker Syndrome and Dentinogenesis].

    PubMed

    Hitosugi, Takashi; Tsukamoto, Masanori; Fujiwara, Shigeki; Yokoyama, Takeshi

    2016-03-01

    Dandy-Walker syndrome (DWS) is characterized by perfect or partial defect of the cerebellum vermis and cystic dilatation of the posterior fossa communicating with the fourth ventricle. Common clinical signs are mental retardation, cerebellar ataxia, and those of increased intracranial pressure (ICP). Associated congenital anomalies are craniofacial, cardiac, renal, and skeletal abnormalities. We experienced a case of intravenous sedation and six times of "the same day" general anesthesia for a school-aged boy (10-13 years old) with DWS and hypodentinogenesis. The patient underwent an examination and dental treatments. We had to pay attention to airway management tracheal tube selection and control of ICP. In addition, we should prevent tooth injuries through mishaps during tracheal intubations, since all-tooth-hypoplasia with fragile dental crowns was strongly suggested in this case. Detailed postoperative care is also required for general anesthesia afflicted with DWS. PMID:27097514

  16. 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.

  17. An Automated Three-Dimensional Detection and Segmentation Method for Touching Cells by Integrating Concave Points Clustering and Random Walker Algorithm

    PubMed Central

    Gong, Hui; Chen, Shangbin; Zhang, Bin; Ding, Wenxiang; Luo, Qingming; Li, Anan

    2014-01-01

    Characterizing cytoarchitecture is crucial for understanding brain functions and neural diseases. In neuroanatomy, it is an important task to accurately extract cell populations' centroids and contours. Recent advances have permitted imaging at single cell resolution for an entire mouse brain using the Nissl staining method. However, it is difficult to precisely segment numerous cells, especially those cells touching each other. As presented herein, we have developed an automated three-dimensional detection and segmentation method applied to the Nissl staining data, with the following two key steps: 1) concave points clustering to determine the seed points of touching cells; and 2) random walker segmentation to obtain cell contours. Also, we have evaluated the performance of our proposed method with several mouse brain datasets, which were captured with the micro-optical sectioning tomography imaging system, and the datasets include closely touching cells. Comparing with traditional detection and segmentation methods, our approach shows promising detection accuracy and high robustness. PMID:25111442

  18. Geodetic Constraints on the Rigidity and Eastern Boundary of the Sierra Nevada Micro-Plate, from Mohawk Valley to Southern Walker Lane

    NASA Astrophysics Data System (ADS)

    Kreemer, C. W.; Hammond, W. C.; Blewitt, G.

    2009-12-01

    The Sierra Nevada - Great Valley (SNGV) micro-plate has long been recognized as a tectonically rigid, though mobile, entity within the Pacific - North America plate boundary zone. The motion of the SNGV relative to stable North America (and the Colorado Plateau) provides the kinematic boundary condition for, and perhaps drives, the deformation in the Basin and Range Province (BRP) and Walker Lane. In the north the motion of the SNGV is aligned with the Mohawk Valley fault zone, which could have a slip rate of over a few mm/yr. The crest of the Sierras marks the SNGV’s eastern edge, but the obliquity between orientation of this boundary and the block’s motion implies an expected increase in rangefront-normal extension from the northern to southern Walker Lane. We use new GPS data from the EarthScope Plate Boundary Observatory (PBO) and our own semi-continuous MAGNET network to revisit the following questions: 1) Do the data still support rigidity of the SNGV?; 2) How far east does the rigidity extend and how does this relate to SNGV lithology?; 3) How does the direction of SNGV motion relate to the strike of its eastern margin and observed strain partitioning (and its along strike variation) in the Walker Lane?; and 4) How is SNGV-BRP motion accommodated between the Walker Lane and the Cascadia forearc? We analyze data from all the available continuous GPS sites in the greater SNGV region, including new data from PBO, as well as data from MAGNET. All data are processed with the GIPSY-OASIS II precise point positioning software using recently reprocessed orbits from JPL's IGS Analysis Center. The processing includes satellite and station antenna calibrations and all data have the phase ambiguities fixed using the Ambizap algorithm. Positions are estimated in our custom-made North America reference frame in which continental-scale common-mode errors are removed. Velocities and uncertainties are estimated using the CATS software in which we assuming an error model

  19. Olfactory Response and Host Plant Feeding of the Central American Locust Schistocerca piceifrons piceifrons Walker to Common Plants in a Gregarious Zone.

    PubMed

    Poot-Pech, M A; Ruiz-Sánchez, E; Ballina-Gómez, H S; Gamboa-Angulo, M M; Reyes-Ramírez, A

    2016-08-01

    The Central American locust (CAL) Schistocerca piceifrons piceifrons Walker is one of the most harmful plant pests in the Yucatan Peninsula, where an important gregarious zone is located. The olfactory response and host plant acceptance by the CAL have not been studied in detail thus far. In this work, the olfactory response of the CAL to odor of various plant species was evaluated using an olfactometer test system. In addition, the host plant acceptance was assessed by the consumption of leaf area. Results showed that the CAL was highly attracted to odor of Pisonia aculeata. Evaluation of host plant acceptance showed that the CAL fed on Leucaena glauca and Waltheria americana, but not on P. aculeata or Guazuma ulmifolia. Analysis of leaf thickness, and leaf content of nitrogen (N) and carbon (C) showed that the CAL was attracted to plant species with low leaf C content. PMID:26957085

  20. Neotectonics, geodesy, and seismic hazard in the Northern Walker Lane of Western North America: Thirty kilometers of crustal shear and no strike-slip?

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.; Bormann, Jayne M.; Kreemer, Corné; Hammond, William C.; Brune, James N.

    2012-05-01

    Roughly 30 km of cumulative right-lateral crustal displacement and 5-6 mm/yr of the ongoing relative right-lateral motion between the Pacific and North American plates are observed in the northern Walker Lane. The right-lateral shear has been accommodated in large part by the development of a set of discontinuous, en echelon, normal fault-bounded basins and perhaps significant vertical axis rotations of the intervening crust. The observations provide an illustrative example of how large amounts of crustal shear may be accommodated in the absence of strike-slip faults and point to difficulties attendant to melding geologic and geodetic observations in the analysis of seismic hazard. In this particular case, the assumption that all geodetically observed shear across the area will be recorded by earthquake displacements may be flawed.

  1. Distributed extensional deformation in a zone of right-lateral shear: Implications for geodetic versus geologic rates of deformation in the eastern California shear zone-Walker Lane

    NASA Astrophysics Data System (ADS)

    Foy, T. Andrew; Frankel, Kurt L.; Lifton, Zachery M.; Johnson, Christopher W.; Caffee, Marc W.

    2012-08-01

    The eastern California shear zone (ECSZ)-Walker Lane belt represents an important, evolving component of the Pacific-North America plate boundary. Geodetic data suggest the northern ECSZ is accumulating dextral shear at a rate of ˜9.3 mm/a, more than double the total measured late Pleistocene rate at ˜37.5°N. At this latitude, the Silver Peak-Lone Mountain (SPLM) extensional complex plays an important role in accommodating and transferring slip among the strike-slip and normal faults of the ECSZ and Walker Lane. To better understand the recent geodynamic evolution of this region, we determined late Pleistocene extension rates for the Clayton Valley fault zone, one of a series of down-to-the-northwest normal faults comprising the SPLM, using geologic mapping, differential GPS fault scarp surveys, and cosmogenic nuclide geochronology. Extension rates along the Clayton Valley fault zone are time-invariant at 0.1 ± 0.1 to 0.3 ± 0.1 mm/a (depending on fault dip) since ˜137 ka. When combined with other published fault slip rates at this latitude, the cumulative late Pleistocene geologic slip rate is ˜3.3 to 5.2 mm/a. This rate is lower than both the geodetic rate of dextral shear and other long-term slip rate budgets in the northern ECSZ. Our results suggest that deformation in Clayton Valley is spread across a diffuse set of normal faults and that not all of the deformation is recorded in the surficial geology. We suggest that the low cumulative geologic slip rate in the northern ECSZ may be a result of this distributed extension, which can cause long-term rates of deformation to be significantly underestimated.

  2. Comparative Pharmacokinetics of Ginsenoside Rg3 and Ginsenoside Rh2 after Oral Administration of Ginsenoside Rg3 in Normal and Walker 256 Tumor-bearing Rats

    PubMed Central

    Fan, He; Xiao-ling, Sun; Yaliu, Su; Ming-ming, Lu; Xue, Feng; Xian-sheng, Meng; Li, Fu

    2016-01-01

    Background: Ginseng is Chinese traditional herbal medicine, and the ginsenoside Rg3 is the main bioactive ingredient for the anti-tumor effect. However, there is no study on pharmacokinetics (PKs) of ginsenoside Rg3 and its main metabolite after oral ginsenoside Rg3 in tumor-bearing plasma. The aim of this study was to investigate the PK profiles of ginsenoside Rg3 and ginsenoside Rh2 after oral administration of pure ginsenoside Rg3 were administered, and compare the difference of the PK profiles between normal and Walker 256 tumor-bearing rats. Materials and Methods: The concentrations of two ginsenosides in plasma were determined by using a simple and rapid high-performance liquid chromatography. All the rats were divided randomly into two groups (Walker 256 tumor-bearing and normal groups). Each group received oral administration of 50 mg/kg ginsenoside Rg3. Results: The results showed that ginsenoside Rh2, possibly as a glycosylation hydrolysis product of ginsenoside Rg3, were found in plasma after oral administration of ginsenoside Rg3 to rats. Ginsenoside Rg3 had shown better absorption than ginsenoside Rh2, whether the oral administration of ginsenoside Rg3, normal rats showed better absorption than tumor-bearing rats. Discussion and Conclusion: The PKs properties of the ginsenoside Rg3 and ginsenoside Rh2 differed between tumor-bearing rats and normal rats, including area under the plasma level/time curve and concentration maximum (P < 0.05). SUMMARY Ginsenoside Rh2 was found in plasma after oral administration of ginsenoside Rg3 to ratsHPLC could be used to determine simultaneously, the concentration of ginsenoside Rg3 and ginsenoside Rh2 in rat plasma after oral administration of ginsenoside Rg3Normal rats showed better absorption than tumor-bearing rats after oral administration of ginsenoside Rg3.0. PMID:27019557

  3. 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 δ13C and δ18O 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.

  4. Stromatolites provide a terrestrial record of a ~35ka warming event in Walker Lake, a remnant of the Pleistocene Lake Lahontan (Western Nevada, USA)

    NASA Astrophysics Data System (ADS)

    Juarez Rivera, M.; Agić, H.; Ward, L.; Kerrigan, Z.; Petryshyn, V. A.; Frantz, C. M.; Tripati, A.; Corsetti, F. A.; Spear, J. R.

    2014-12-01

    Walker Lake is a closed-basin remnant of the large Pleistocene glacial Lake Lahontan that has experienced drastic changes in water level. Carbonate structures, such as stromatolites, precipitated from the lake and were studied as potential sources for historical climate change. A 16.7 cm long stromatolite was collected from a paleoshoreline approximately 58 meters above the present Walker Lake surface elevation. Radiocarbon dating revealed that the stromatolite spans approximately 2,000 years of growth, from 35,540 to 33,580 Calibrated YBP (IntCal13). Distinct laminae were drilled along the growth axis, and the resulting powders were collected for clumped isotope analyses, which uses the amount of heavy CO2 "clumps" (13C-18O-16O, or ∆47) generated from the dissolution of carbonate in acid to measure the temperature of formation of a rock. Using this method, we tracked the change in lake temperature and δ18Ofluid during stromatolite formation. Our results show that the stromatolite experienced an overall increase in temperature and δ18Ofluid values during the course of accretion. The resulting data were input to a Rayleigh distillation model for water evaporation in order to estimate the magnitude of lake level and volume fluctuations. Our modeling results show that, during the course of stromatolite accretion, the lake experienced a volume decrease of ~5 Km3, corresponding to lake level fall of ~14 meters. This study shows that lacustrine material (such as stromatolites or other tufas) can potentially be used to reconstruct the timing and magnitude of terrestrial climate change during important transitions in Earth history.

  5. Assessment of forearm and plantar foot load in the elderly using a four-wheeled walker with armrest and the effect of armrest height

    PubMed Central

    Ko, Chang-Yong; Kim, Sol-Bi; Choi, Hyuk-Jae; Chang, Yunhee; Kang, Sungjae; Heo, Yoon; Ryu, Jeicheong; Kim, Gyoosuk; Mun, Museong

    2014-01-01

    Background Patients with hand and/or wrist pathology are recommended to have a four-wheeled walker with an arm rest (FWW-AR) rather than a standard walker or a standard four-wheeled walker (FWW). However, only a few quantitative studies have been performed to compare upper and lower extremity weight bearing. The aim of this study was to evaluate forearm and foot weight bearing using a FWW-AR and the effect of the armrest height. Methods Eleven elderly women (mean age 80.1±5.3 years; mean height 148.5±4.0 cm; mean weight 51.2±9.0 kg) were enrolled. The subjects walked with an FWW-AR, with the elbow in either 90 degree (D90) or 130 degree (D130) flexion, for a distance of 10 m. Surface electromyographic signals were recorded for the upper, middle, and lower trapezius, anterior deltoid, and erector spinae muscles; walking velocity was measured with the subjects weight bearing on their feet and forearms while walking. Simultaneously, the maximum plantar and forearm loads during walking with an FWW-AR were measured. Results The normalized foot plantar loads were lower at D90 than at D130, while the normalized forearm load was higher at D90 than at D130 (all P<0.05; left foot, 7.9±0.1 N/kg versus 8.8±0.1 N/kg; right foot, 8.6±0.2 N/kg versus. 9.6±0.1 N/kg; left forearm, 1.8±0.5 N/kg versus 0.8±0.2 N/kg; and right forearm, 2.0±0.5 N/kg versus 1.0±0.2 N/kg, respectively). The surface electromyographic activity of the muscles involved in shoulder elevation and the walking velocity were both lower with the elbow at D90 than at D130 (all P<0.05; left upper trapezius, 98.7%±19.5% versus 132.6%±16.9%; right upper trapezius, 83.4%±10.6% versus 108.1%±10.5%; left anterior deltoid, 94.1%±12.8% versus 158.6%±40.4%; right anterior deltoid, 99.1%±15.0% versus 151.9%±19.4%; and velocity, 0.6±0.1 m/sec versus 0.7±0.1 m/sec, respectively). Conclusion Weight bearing on the lower extremities is significantly reduced when the upper extremities are supported during

  6. 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

  7. 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

  8. Cosmology of a Friedmann-Lamaître-Robertson-Walker 3-brane, late-time cosmic acceleration, and the cosmic coincidence.

    PubMed

    Doolin, Ciaran; Neupane, Ishwaree P

    2013-04-01

    A late epoch cosmic acceleration may be naturally entangled with cosmic coincidence--the observation that at the onset of acceleration the vacuum energy density fraction nearly coincides with the matter density fraction. In this Letter we show that this is indeed the case with the cosmology of a Friedmann-Lamaître-Robertson-Walker (FLRW) 3-brane in a five-dimensional anti-de Sitter spacetime. We derive the four-dimensional effective action on a FLRW 3-brane, from which we obtain a mass-reduction formula, namely, M(P)(2) = ρ(b)/|Λ(5)|, where M(P) is the effective (normalized) Planck mass, Λ(5) is the five-dimensional cosmological constant, and ρ(b) is the sum of the 3-brane tension V and the matter density ρ. Although the range of variation in ρ(b) is strongly constrained, the big bang nucleosynthesis bound on the time variation of the effective Newton constant G(N) = (8πM(P)(2))(-1) is satisfied when the ratio V/ρ ≳ O(10(2)) on cosmological scales. The same bound leads to an effective equation of state close to -1 at late epochs in accordance with astrophysical and cosmological observations. PMID:25166976

  9. 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

  10. Fukutin mutations in non-Japanese patients with congenital muscular dystrophy: less severe mutations predominate in patients with a non-Walker-Warburg phenotype.

    PubMed

    Yis, Uluc; Uyanik, Gökhan; Heck, Pinar Bambul; Smitka, Martin; Nobel, Hannes; Ebinger, Friedrich; Dirik, Eray; Feng, Lucy; Kurul, Semra H; Brocke, Katja; Unalp, Aycan; Özer, Erdener; Cakmakci, Handan; Sewry, Caroline; Cirak, Sebahattin; Muntoni, Francesco; Hehr, Ute; Morris-Rosendahl, Deborah J

    2011-01-01

    Six genes including POMT1, POMT2, POMGNT1, FKRP, Fukutin (FKTN) and LARGE encode proteins involved in the glycosylation of α-dystroglycan (α-DG). Abnormal glycosylation of α-DG is a common finding in Walker-Warburg syndrome (WWS), muscle-eye-brain disease (MEB), Fukuyama congenital muscular dystrophy (FCMD), congenital muscular dystrophy types 1C and 1D and some forms of autosomal recessive limb-girdle muscular dystrophy (LGMD2I, LGMD2K, LGMD2M), and is associated with mutations in the above genes. FCMD, caused by mutations in Fukutin (FKTN), is most frequent in Japan, but an increasing number of FKTN mutations are being reported outside of Japan. We describe four new patients with FKTN mutations and phenotypes ranging from: severe WWS in a Greek-Croatian patient, to congenital muscular dystrophy and cobblestone lissencephaly resembling MEB-FCMD in two Turkish patients, and limb-girdle muscular dystrophy and no mental retardation in a German patient. Four of the five different FKTN mutations have not been previously described. PMID:20961758

  11. [Morphological and molecular identification of Prosapia simulans (Walker) (Hemiptera: Cercopidae), and screening and mechanisms of resistance to this spittlebug in Brachiaria hybrids].

    PubMed

    Castro, Ulises; Cardona, Cesar; Vera-Graziano, Jorge; Miles, John; Garza-Garcia, Ramón

    2007-01-01

    Prosapia simulans (Walker) is an important spittlebug species that attacks forage grasses of the genus Brachiaria (Trin.) Griseb. from Mexico to Colombia. This, and several other species of spittlebugs, cause important economic losses to the livestock production industry. Development of resistant cultivars is regarded as the best method of control. In the present study we used taxonomic keys, dissection of male genitalia and RAPD-PCR patterns to reconfirm the identity of P. simulans specimens collected in Colombia and Mexico. We were able to reconfirm that P. simulans occurs as a pest of Brachiaria from Mexico to Colombia. We also studied the levels and mechanisms of resistance present in 34 Brachiaria hybrids developed by CIAT. Infestations were made with six eggs per plant. We used 10 replications (plants) per genotype in a completely randomized design. Seven hybrids were found to be susceptible, 16 showed intermediate resistance and 11 were resistant. Antibiosis was the mechanism of resistance expressed in resistant hybrids as well as in the resistant checks CIAT 6294 and CIAT 36062. Tolerance was absent. The genotypes BRX 4402 and CIAT 0606 were classified as highly susceptible. PMID:17934620

  12. Effect of malignant ascites on antioxidative potency of two tumoral cells-induced bone metastases: Walker 256/B and MatLyLu.

    PubMed

    Badraoui, R; Rebai, T

    2012-01-01

    This study was undertaken to estimate antioxidative status of two malignant-mammary gland carcinoma (Walker 256/B) and malignant-prostate carcinoma cells (MatLyLu) disseminated in ascitic fluids. Malignant carcinoma cells (10(7) cells) were twice serially intraperitoneal injected in male Wistar rats to develop ascites. After 7 days, ascitic fluids were collected, and cells in suspension were usable for biological assays. Cellular lipid peroxidation was assessed by measuring thiobarbituric acid reactive substances (TBARS) levels. Some antioxidant parameters: superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) were also assessed. Comparisons with control baseline (cells maintained in normal culture medium) were analyzed. TBARS levels were found to be significantly decreased in both ascitic cancer cells compared to the baseline except for in the ascite I of MatLyLu cells. On the other hand, SOD and CAT activities were found to be statistically increased in the two malignant ascitic passages. GSH-Px levels were elevated in the first and in the second ascitic passages (p<0.05 and p<0.01, respectively). Our results suggest that malignant ascites are associated not only with reduced levels of TBARS but also with increased antioxidant parameters, indicating the increasing antioxidant potency of two cancer cells during malignancies process. PMID:20605085

  13. An approach for reconstructing past streamflows using a water balance model and tree-ring records in the upper West Walker River basin, California

    NASA Astrophysics Data System (ADS)

    Vittori, J. C.; Saito, L.; Biondi, F.

    2010-12-01

    Historical streamflows in a given river basin can be useful for determining regional patterns of drought and climate, yet such measured data are typically available for the last 100 years at most. To extend the measured record, observed streamflows can be regressed against tree-ring data that serve as proxies for streamflow. This empirical approach, however, cannot account for or test factors that do not directly affect tree-ring growth but may influence streamflow. To reconstruct past streamflows in a more mechanistic way, a seasonal water balance model has been developed for the upper West Walker River basin that uses proxy precipitation and air temperature data derived from tree-ring records as input. The model incorporates simplistic relationships between precipitation and other components of the hydrologic cycle, as well as a component for modeling snow, and operates at a seasonal time scale. The model allows for flexibility in manipulating various hydrologic and land use characteristics, and can be applied to other watersheds. The intent is for the model to investigate sources of uncertainty in streamflow reconstructions, and how factors such as wildfire or changes in vegetation cover could impact estimates of past flows, something regression-based models are not able to do. In addition, the use of a mechanistic water balance model calibrated against proxy climate records can provide information on changes in various components of the water cycle, including the interaction between evapotranspiration, snowmelt, and runoff under warmer climatic regimes.

  14. Oral administration of Aloe vera and honey reduces Walker tumour growth by decreasing cell proliferation and increasing apoptosis in tumour tissue.

    PubMed

    Tomasin, Rebeka; Gomes-Marcondes, Maria Cristina Cintra

    2011-04-01

    Cancer is diagnosed in approximately 11 million people and is responsible for almost 8 million deaths worldwide every year. Research in cancer control has shown the importance of co-adjuvant therapies. Aloe vera may reduce tumour mass and metastasis rates, while honey may inhibit tumour growth. This study verified the influence of Aloe vera and honey on tumour growth and in the apoptosis process by assessing tumour size, the cell proliferation rate (Ki67-LI) and Bax/Bcl-2 expression at 7, 14 and 20 days after Walker 256 carcinoma implant in Wistar rats distributed into two groups: the WA group - tumour-bearing rats that received a gavage with a 670 µL/kg dose of Aloe vera and honey solution daily, and the CW group - tumour-bearing rats which received only a 0.9% NaCl solution. The effect of Aloe vera and honey against tumour growth was observed through a decrease in relative weight (%) and Ki67-LI in tumours from the WA group compared with those from the CW group. The Bax/Bcl-2 ratio increased in tumours from the WA group at all tested timepoints. These data suggest Aloe vera and honey can modulate tumour growth by reducing cell proliferation and increasing apoptosis susceptibility. PMID:20839215

  15. Mutations in Sensor 1 and Walker B in the Bovine Papillomavirus E1 Initiator Protein Mimic the Nucleotide-Bound State▿

    PubMed Central

    Liu, Xiaofei; Stenlund, Arne

    2010-01-01

    Viral replication initiator proteins are multifunctional proteins that utilize ATP binding and hydrolysis by their AAA+ modules for multiple functions in the replication of their viral genomes. These proteins are therefore of particular interest for understanding how AAA+ proteins carry out multiple ATP driven functions. We have performed a comprehensive mutational analysis of the residues involved in ATP binding and hydrolysis in the papillomavirus E1 initiator protein based on the recent structural data. Ten of the eleven residues that were targeted were defective for ATP hydrolysis, and seven of these were also defective for ATP binding. The three mutants that could still bind nucleotide represent the Walker B motif (D478 and D479) and Sensor 1 (N523), three residues that are in close proximity to each other and generally are considered to be involved in ATP hydrolysis. Surprisingly, however, two of these mutants, D478A and N523A, mimicked the nucleotide bound state and were capable of binding DNA in the absence of nucleotide. However, these mutants could not form the E1 double trimer in the absence of nucleotide, demonstrating that there are two qualitatively different consequences of ATP binding by E1, one that can be mimicked by D478A and N523A and one which cannot. PMID:19939914

  16. Novel SIL1 nonstop mutation in a Chinese consanguineous family with Marinesco-Sjögren syndrome and Dandy-Walker syndrome.

    PubMed

    Gai, Nan; Jiang, Chen; Zou, Yong-Yi; Zheng, Yu; Liang, De-Sheng; Wu, Ling-Qian

    2016-07-01

    Marinesco-Sjögren syndrome (MSS) is a rare autosomal recessive disorder, which is characterized by congenital cataracts, cerebellar ataxia, progressive muscle weakness, and delayed psychomotor development. SIL1, which is located at 5q31.2, is the only gene known to cause MSS. Dandy-Walker syndrome (DWS) is defined by hypoplasia, upward rotation of the cerebellar vermis, and cystic dilation of the fourth ventricle; however, its genetic pathogeny remains unclear. Here, we report a Chinese consanguineous family with MSS and DWS. Whole exome sequencing identified a novel nonstop mutation in SIL1. Sanger sequencing revealed that the mutation was segregated in this family according to a recessive mode of inheritance. We found that the mutation changed a stop codon (TGA) to an arginine codon (CGA), and no in-frame termination codon in the 3' untranslated region (UTR) of SIL1 could be found. The mRNA levels of SIL1 were decreased by 56.6% and 37.5% in immortalized lymphoblasts of the patients respectively; the protein levels of SIL1 were substantially decreased. This case study is the first report on Chinese MSS patients, MSS complicated by DWS, and a nonstop mutation in SIL1. Our findings imply the pathogenetic association between DWS and MSS. PMID:27106665

  17. High K volcanism in the Sierra Nevada: A signal for the initiation of Walker Lane Faulting, and range uplift, not lithosphere delamination

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.; Busby, C. J.

    2007-12-01

    K2O contents have long been recognized as a potential indicator of tectonic processes, and based upon models developed for the Andes (Kay and Kay, 1993) and Tibet (Turner et al., 1996), high-K volcanism has been related to lithosphere delamination, by partial melting of a K-metasomatized lower crust or upper mantle (Feldstein and Lange, 1999; Manley et al., 2000). However, new data from the central Sierra Nevada cast doubt on this K2O-delamination link. Instead, high-K volcanism is better explained as low degree partial melts (F), where low F magmas are preferentially erupted over thick crust, under conditions of high tensile stress. In the central Sierra, a high tensile stress regime was imposed at the onset of Walker Lane transtension, at the eastern edge of the Basin and Range province. We surmise that high K volcanism is similarly controlled by the onset of tensile stresses throughout the Sierra, recording the initial phase of Sierra Nevada uplift. These conclusions stem from several observations. First, K2O contents are highly correlated with Th (R=0.82), Ba (R=0.83), U (R=0.85), Rb (R=0.88) and Pb (R=0.83), and other highly incompatible elements, suggesting a general enrichment mechanism, such as low degree partial melitng. Second, volcanic rocks with the highest K have the highest La/Nb and the lowest 143Nd/144Nd, indicative of a mantle lithosphere source - inconsistent with delamination. Third, maximum K contents increase from north (near Lassen) to south, following in increase in crustal thickness and the (87Sr/86Sr) i of basement granitoids, suggestive of a crustal control on volcanism. Finally, field evidence in the central Sierra shows that the pulse of high K2O volcanism there was synchronous with the development of a pull-apart, along a series of right-stepping dextral transtensional faults, at the onset of Walker Lane faulting. Partial melting calculations verify that primitive magma compositions from Lassen to the southern Sierra, can all be

  18. Uncaria tomentosa exerts extensive anti-neoplastic effects against the Walker-256 tumour by modulating oxidative stress and not by alkaloid activity.

    PubMed

    Dreifuss, Arturo Alejandro; Bastos-Pereira, Amanda Leite; Fabossi, Isabella Aviles; Lívero, Francislaine Aparecida Dos Reis; Stolf, Aline Maria; Alves de Souza, Carlos Eduardo; Gomes, Liana de Oliveira; Constantin, Rodrigo Polimeni; Furman, Aline Emmer Ferreira; Strapasson, Regiane Lauriano Batista; Teixeira, Simone; Zampronio, Aleksander Roberto; Muscará, Marcelo Nicolás; Stefanello, Maria Elida Alves; Acco, Alexandra

    2013-01-01

    This study aimed to compare the anti-neoplastic effects of an Uncaria tomentosa (UT) brute hydroethanolic (BHE) extract with those of two fractions derived from it. These fractions are choroformic (CHCl3) and n-butanolic (BuOH), rich in pentacyclic oxindole alkaloids (POA) and antioxidant substances, respectively. The cancer model was the subcutaneous inoculation of Walker-256 tumour cells in the pelvic limb of male Wistar rat. Subsequently to the inoculation, gavage with BHE extract (50 mg.kg(-1)) or its fractions (as per the yield of the fractioning process) or vehicle (Control) was performed during 14 days. Baseline values, corresponding to individuals without tumour or treatment with UT, were also included. After treatment, tumour volume and mass, plasma biochemistry, oxidative stress in liver and tumour, TNF-α level in liver and tumour homogenates, and survival rates were analysed. Both the BHE extract and its BuOH fraction successfully reduced tumour weight and volume, and modulated anti-oxidant systems. The hepatic TNF-α level indicated a greater effect from the BHE extract as compared to its BuOH fraction. Importantly, both the BHE extract and its BuOH fraction increased the survival time of the tumour-bearing animals. Inversely, the CHCl3 fraction was ineffective. These data represent an in vivo demonstration of the importance of the modulation of oxidative stress as part of the anti-neoplastic activity of UT, as well as constitute evidence of the lack of activity of isolated POAs in the primary tumour of this tumour lineage. These effects are possibly resulting from a synergic combination of substances, most of them with antioxidant properties. PMID:23408945

  19. Crustal deformation across the Sierra Nevada, northern Walker Lane, Basin and Range transition, western United States measured with GPS, 2000-2004

    NASA Astrophysics Data System (ADS)

    Hammond, William C.; Thatcher, Wayne

    2007-05-01

    Global Positioning System (GPS) data collected in campaigns in 2000 and 2004 were processed and interpreted with other GPS data in the western Basin and Range province to provide new constraints on the rate, style, and pattern of deformation of the central and northern Walker Lane (WL), which lies near the western boundary of the Basin and Range. Across the central WL, near 38°N latitude, the velocities with respect to North America increase westward by ˜10 mm/yr inducing dextral shear. Farther north between 40° and 41°N latitude, a western zone of ˜7 mm/yr relative motion undergoes dextral shear, and an eastern zone of ≤3 mm/yr relative motion undergoes extension and shear. These data show that the northern WL is essentially a dextral shear zone experiencing minor net dilatation (ɛΔ = 2.6 ± 0.8 nstrain/yr). Near most Holocene normal faults, dilatation inferred from the velocity field is not greater than the uncertainties. However, near the central Nevada seismic belt we detect significant dilatation expressed as extension in a direction approximately normal to the range fronts (ɛΔ = 23.0 ± 3.9 nstrain/yr), some of which is attributable to transient postseismic deformation following large historic earthquakes. A block model constrained by velocities corrected for transient effects shows that the sum of dextral slip rates across the Honey Lake, Warm Springs, east Pyramid fault system, and Mohawk Valley faults is ˜7 mm/yr. The WL is a zone whose width and dilatation rate increase northwestward, consistent with counterclockwise rotation of the Sierra Nevada microplate and transfer of deformation into the Pacific Northwest.

  20. Uncaria tomentosa Exerts Extensive Anti-Neoplastic Effects against the Walker-256 Tumour by Modulating Oxidative Stress and Not by Alkaloid Activity

    PubMed Central

    Dreifuss, Arturo Alejandro; Bastos-Pereira, Amanda Leite; Fabossi, Isabella Aviles; Lívero, Francislaine Aparecida dos Reis; Stolf, Aline Maria; Alves de Souza, Carlos Eduardo; Gomes, Liana de Oliveira; Constantin, Rodrigo Polimeni; Furman, Aline Emmer Ferreira; Strapasson, Regiane Lauriano Batista; Teixeira, Simone; Zampronio, Aleksander Roberto; Muscará, Marcelo Nicolás; Stefanello, Maria Elida Alves; Acco, Alexandra

    2013-01-01

    This study aimed to compare the anti-neoplastic effects of an Uncaria tomentosa (UT) brute hydroethanolic (BHE) extract with those of two fractions derived from it. These fractions are choroformic (CHCl3) and n-butanolic (BuOH), rich in pentacyclic oxindole alkaloids (POA) and antioxidant substances, respectively. The cancer model was the subcutaneous inoculation of Walker-256 tumour cells in the pelvic limb of male Wistar rat. Subsequently to the inoculation, gavage with BHE extract (50 mg.kg−1) or its fractions (as per the yield of the fractioning process) or vehicle (Control) was performed during 14 days. Baseline values, corresponding to individuals without tumour or treatment with UT, were also included. After treatment, tumour volume and mass, plasma biochemistry, oxidative stress in liver and tumour, TNF-α level in liver and tumour homogenates, and survival rates were analysed. Both the BHE extract and its BuOH fraction successfully reduced tumour weight and volume, and modulated anti-oxidant systems. The hepatic TNF-α level indicated a greater effect from the BHE extract as compared to its BuOH fraction. Importantly, both the BHE extract and its BuOH fraction increased the survival time of the tumour-bearing animals. Inversely, the CHCl3 fraction was ineffective. These data represent an in vivo demonstration of the importance of the modulation of oxidative stress as part of the anti-neoplastic activity of UT, as well as constitute evidence of the lack of activity of isolated POAs in the primary tumour of this tumour lineage. These effects are possibly resulting from a synergic combination of substances, most of them with antioxidant properties. PMID:23408945

  1. 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

  2. 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

  3. Mutations in the O-mannosyltransferase gene POMT1 give rise to the severe neuronal migration disorder Walker-Warburg syndrome.

    PubMed

    Beltrán-Valero de Bernabé, Daniel; Currier, Sophie; Steinbrecher, Alice; Celli, Jacopo; van Beusekom, Ellen; van der Zwaag, Bert; Kayserili, Hülya; Merlini, Luciano; Chitayat, David; Dobyns, William B; Cormand, Bru; Lehesjoki, Ana-Elina; Cruces, Jesús; Voit, Thomas; Walsh, Christopher A; van Bokhoven, Hans; Brunner, Han G

    2002-11-01

    Walker-Warburg syndrome (WWS) is an autosomal recessive developmental disorder characterized by congenital muscular dystrophy and complex brain and eye abnormalities. A similar combination of symptoms is presented by two other human diseases, muscle-eye-brain disease (MEB) and Fukuyama congenital muscular dystrophy (FCMD). Although the genes underlying FCMD (Fukutin) and MEB (POMGnT1) have been cloned, loci for WWS have remained elusive. The protein products of POMGnT1 and Fukutin have both been implicated in protein glycosylation. To unravel the genetic basis of WWS, we first performed a genomewide linkage analysis in 10 consanguineous families with WWS. The results indicated the existence of at least three WWS loci. Subsequently, we adopted a candidate-gene approach in combination with homozygosity mapping in 15 consanguineous families with WWS. Candidate genes were selected on the basis of the role of the FCMD and MEB genes. Since POMGnT1 encodes an O-mannoside N-acetylglucosaminyltransferase, we analyzed the possible implication of O-mannosyl glycan synthesis in WWS. Analysis of the locus for O-mannosyltransferase 1 (POMT1) revealed homozygosity in 5 of 15 families. Sequencing of the POMT1 gene revealed mutations in 6 of the 30 unrelated patients with WWS. Of the five mutations identified, two are nonsense mutations, two are frameshift mutations, and one is a missense mutation. Immunohistochemical analysis of muscle from patients with POMT1 mutations corroborated the O-mannosylation defect, as judged by the absence of glycosylation of alpha-dystroglycan. The implication of O-mannosylation in MEB and WWS suggests new lines of study in understanding the molecular basis of neuronal migration. PMID:12369018

  4. 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

  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

  6. 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

  7. Paleomagnetic Data Bearing on the Evolution of the Walker Lane Belt Transfer Zone From mid-Miocene to Present: an Investigation of the Inferred Southern and Eastern Boundaries.

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    The Walker Lane Belt (WLB) transfer zone, which initiated in the mid-Miocene, presently links the Eastern California Shear Zone (ECSZ) in the south to the Central Nevada Seismic Belt (CNSB) and WLB to the east and north, respectively. This transfer zone is part of a diffuse intracontinental deformation zone that accommodates some 25 percent of the current motion between the North American and Pacific plates. The boundary of the transfer system is clear on the northern and western margins but the extent of the system to the south and east is only inferred. The extent of deformation and development of the WLB transfer zone since the mid-Miocene is being examined by a paleomagnetic study of 125 sites that includes Miocene to mid-Pliocene volcanic and shallow intrusive rocks near the inferred southern and eastern boundaries. Results from 39 sites inside and along the southern boundary (i.e. Goldfield Hills, Montezuma Range, Clayton Ridge) show about 30° of clockwise rotation (D = 028.3°, I = 57.8°, α95 = 3.9°, discordant from the expected Neogene direction of D = 358°, I = 55°). The area where 13 of these 39 sites are located (i.e. northern Amargosa Range, eastern Slate Ridge) was previously thought to lie outside of the inferred boundary, yet it also shows about 30° of clockwise rotation (D = 031.2°, I = 52.4°, α95 = 6.7°). Areas along the eastern boundary (i.e. southern San Antonio Range) of the transfer zone are still under investigation; data obtained to date are not internally consistent. Overall, the available paleomagnetic data suggest that the southern extent of the WLB transfer zone was larger than previously expected during the mid-Miocene to mid-Pliocene, and based on previous paleomagnetic, structural, and geodetic studies of the area, support a transition from more diffuse to localized deformation (forming the Mina Deflection) at about 3 Ma.

  8. Mutation of Walker-A lysine 464 in cystic fibrosis transmembrane conductance regulator reveals functional interaction between its nucleotide-binding domains.

    PubMed

    Powe, Allan C; Al-Nakkash, Layla; Li, Min; Hwang, Tzyh-Chang

    2002-03-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel bears two nucleotide-binding domains (NBD1 and NBD2) that control its ATP-dependent gating. Exactly how these NBDs control gating is controversial. To address this issue, we examined channels with a Walker-A lysine mutation in NBD1 (K464A) using the patch clamp technique. K464A mutants have an ATP dependence (EC(50) approximate 60 microM) and opening rate at 2.75 mM ATP (approximately 2.1 s(-1)) similar to wild type (EC(50) approximate 97 microM; approximately 2.0 s(-1)). However, K464A's closing rate at 2.75 mM ATP (approximately 3.6 s(-1)) is faster than that of wild type (approximately 2.1 s(-1)), suggesting involvement of NBD1 in nucleotide-dependent closing. Delay of closing in wild type by adenylyl imidodiphosphate (AMP-PNP), a non-hydrolysable ATP analogue, is markedly diminished in K464A mutants due to reduction in AMP-PNP's apparent on-rate and acceleration of its apparent off-rate (approximately 2- and approximately 10-fold, respectively). Since the delay of closing by AMP-PNP is thought to occur via NBD2, K464A's effect on the NBD2 mutant K1250A was examined. In sharp contrast to K464A, K1250A single mutants exhibit reduced opening (approximately 0.055 s(-1)) and closing (approximately 0.006 s(-1)) rates at millimolar [ATP], suggesting a role for K1250 in both opening and closing. At millimolar [ATP], K464A-K1250A double mutants close approximately 5-fold faster (approximately 0.029 s(-1)) than K1250A but open with a similar rate (approximately 0.059 s(-1)), indicating an effect of K464A on NBD2 function. In summary, our results reveal that both of CFTR's functionally asymmetric NBDs participate in nucleotide-dependent closing, which provides important constraints for NBD-mediated gating models. PMID:11882668

  9. Mutation of Walker-A lysine 464 in cystic fibrosis transmembrane conductance regulator reveals functional interaction between its nucleotide-binding domains

    PubMed Central

    Powe, Allan C; Al-Nakkash, Layla; Li, Min; Hwang, Tzyh-Chang

    2002-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel bears two nucleotide-binding domains (NBD1 and NBD2) that control its ATP-dependent gating. Exactly how these NBDs control gating is controversial. To address this issue, we examined channels with a Walker-A lysine mutation in NBD1 (K464A) using the patch clamp technique. K464A mutants have an ATP dependence (EC50 ≈ 60 μm) and opening rate at 2.75 mm ATP (∼ 2.1 s−1) similar to wild type (EC50 ≈ 97 μm; ∼ 2.0 s−1). However, K464A's closing rate at 2.75 mm ATP (∼ 3.6 s−1) is faster than that of wild type (∼ 2.1 s−1), suggesting involvement of NBD1 in nucleotide-dependent closing. Delay of closing in wild type by adenylyl imidodiphosphate (AMP-PNP), a non-hydrolysable ATP analogue, is markedly diminished in K464A mutants due to reduction in AMP-PNP's apparent on-rate and acceleration of its apparent off-rate (∼ 2- and ∼ 10-fold, respectively). Since the delay of closing by AMP-PNP is thought to occur via NBD2, K464A's effect on the NBD2 mutant K1250A was examined. In sharp contrast to K464A, K1250A single mutants exhibit reduced opening (∼ 0.055 s−1) and closing (∼ 0.006 s−1) rates at millimolar [ATP], suggesting a role for K1250 in both opening and closing. At millimolar [ATP], K464A-K1250A double mutants close ∼ 5-fold faster (∼ 0.029 s−1) than K1250A but open with a similar rate (∼ 0.059 s−1), indicating an effect of K464A on NBD2 function. In summary, our results reveal that both of CFTR's functionally asymmetric NBDs participate in nucleotide-dependent closing, which provides important constraints for NBD-mediated gating models. PMID:11882668

  10. 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

  11. An in-silico walker

    NASA Astrophysics Data System (ADS)

    Xiao, Qiran; Chen, Yanping; Bereau, Tristan; Shi, Yunfeng

    2016-08-01

    The paradox of biomimetic research is to perform bio-functionality, usually associated with sophisticated structures optimized by nature, with minimal structural complexity for the ease of fabrication. Here we show that a three-particle trimer can exhibit kinesin-like autonomous walk on a track via reactive molecular dynamics simulations. The autonomous motion is due to imbalanced transitions resulting from exothermic catalytic reactions, and the spatial asymmetry from the track. This molecular design can be realized by reproducing the particle-particle interactions in functionalized nano- or colloidal particles. Our results open up the possibility of fabricating bio-mimetic nano-systems in a minimalist approach.

  12. 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 ...

  13. 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 Ω→gyro of local gyroscopes, which in turn gives the operational definition of the gravitomagnetic field: B→g≡-2Ω→gyro. The gravitomagnetic field is caused by energy currents J→ɛ via the momentum constraint, Einstein’s G0^i^ equation, (-Δ+μ2)A→g=-16πGNJ→ɛ with B→g=curlA→g. This equation is analogous to Ampère’s law, but it holds for all time-dependent situations. Δ is the de Rham-Hodge Laplacian, and Δ=-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 Yμ(r)=(-d/dr)[(1/R)exp⁡(-μr)], form-identical for FRW backgrounds with K=(-1,0). Here r is the measured geodesic distance from the gyroscope to the cosmological source, and 2πR 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 μ2=-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

  14. Maps showing distribution of copper, lead, zinc, cadmium, and silver in samples of minus-60-mesh (0.25-MM) stream sediment and nonmagnetic heavy-mineral concentrate, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

    USGS Publications Warehouse

    Chaffee, M.A.; Hill, R.H.; Sutley, S.J.

    1988-01-01

    This report is part of a folio of maps of the Walker Lake 1o x 2o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resources assessment maps, which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributions of selected individual elements (Chaffee and others, 1988 a, b, c) and the distributions of selected groups of elements (Chaffee, 1988a, b, c). Discussions accompanying the individual element maps are restricted to mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielemental maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits. 

  15. Maps showing distribution of anomalies based on the use of scoresum plots for selected groupings of elements in samples of nonmagnetic heavy-mineral concentrate, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

    USGS Publications Warehouse

    Chaffee, M.A.

    1988-01-01

    This report is part of a folio of maps of the Walker Lake 1o x 2o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resource assessment maps which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributioins of selected individual elements (Chaffee and others 1988a, b, c, d) and the distributions of selected groups of elements (Chaffee, 1988a, b). Discussions accompanying the individual element maps are restricted to possible mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielement maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits. 

  16. Maps showing distribution of anomalies based on the use of scoresum plots for selected groupings of elements in samples of minus-60-mesh (0.25-MM) stream sediment, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

    USGS Publications Warehouse

    Chaffee, M.A.

    1988-01-01

    This report is part of a folio of maps of the Walker Lake 1o x 2o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resources assessment maps, which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributions of selected individual elements (Chaffee and others, 1988 a, b, c) and the distributions of selected groups of elements (Chaffee, 1988a, b, c). Discussions accompanying the individual element maps are restricted to mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielemental maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits. 

  17. Perioperative management of a patient with Dandy Walker malformation with tetralogy of Fallot undergoing total correction and fresh homologous pericardial pulmonary valve conduit implantation: Report of a rare case

    PubMed Central

    Datt, Vishnu; Tempe, D. K.; Lalwani, Parin; Aggarwal, Saket; Kumar, Pradeep; Diwakar, Anitha; Tomar, A. S.

    2015-01-01

    Perioperative management of a patient with Dandy–Walker malformation (DWM) with tetralogy of Fallot (TOF), patent ductus arteriosus, and pulmonary artery stenosis is a great challenge to the anesthesiologist. Anesthetic management in such patients can trigger tet spells that might rapidly increase intracranial pressure (ICP), conning and even death. The increase in ICP can precipitate tet spells and further brain hypoxia. To avoid an increase in ICP during TOF corrective surgery ventriculo-peritoneal (VP) shunt should be performed before cardiac surgery. We present the first case report of a 11-month-old male baby afflicted with DWM and TOF who underwent successful TOF total corrective surgery and fresh autologous pericardial pulmonary valve conduit implantation under cardiopulmonary bypass after 1 week of VP shunt insertion. PMID:26139758

  18. Differential response to L-triiodothyronine of anterior pituitary growth hormone messenger ribonucleic acid (mRNA) and beta-thyrotropin mRNA in a hypothyroid Walker 256 carcinoma-bearing rat model of nonthyroidal disease.

    PubMed

    Hupart, K H; DeFesi, C R; Katz, C P; Shapiro, L E; Surks, M I

    1990-01-01

    To continue our studies on the influence of T3 on TSH regulation in the Walker 256 carcinoma-bearing rat model of nonthyroidal disease, we measured the effect of T3 on pituitary content of beta TSH mRNA and rat (r) TSH in hypothyroid control (C) and tumor-bearing (T) rats. The effect of T3 on TSH regulation was compared to effects on GH mRNA and rGH in the same animals. mRNA content was normalized to a pool of pituitaries from euthyroid rats (= 1.0). beta TSH mRNA increased 18-fold in both hypothyroid C and T rats and then decreased similarly with increasing T3 infusion to a value of 0.1. GH mRNA content decreased to 0.11 +/- 0.01 in hypothyroid C rats, but to only 0.38 +/- 0.02 in T rats (P less than 0.001). The pituitary contents of GH mRNA and rGH in hypothyroid T rats was significantly greater than those in C rats at all T3 infusion rates. These data together with our previous report of decreased nuclear T3 in T rats suggest that regulation of beta TSH mRNA by T3 is intact in T rats, but occurs at a lower concentration of nuclear T3. In contrast, the GH mRNA response is enhanced, displaying differential regulation of these two T3-responsive gene products in this model of nonthyroidal illness. PMID:2294008

  19. Valsalnicola D. Walker & Rossman, gen. nov.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Valsonectria is based on a species that was described in the genus Valsa. Although it resembles Valsa in having allantoid ascospores, the ascospores of Valsalnicola are one-septate while the majority of species of Valsa and the closely related Leucostoma and Valsella have non-septate ascospores. How...

  20. 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…

  1. The hydrodynamics of water-walkers

    NASA Astrophysics Data System (ADS)

    Hu, David L.; Bush, John W. M.

    2004-11-01

    Legged propulsion on the water surface is accomplished through a variety of means by birds, reptiles and insects. Examples include walking, rowing, hopping and capillary locomotion via deformation of the free surface. We here present experimental observations that yield insight into the scaling of water-walking. Particular attention is given to categorizing water-walking creatures and their modes of propulsion according to the relative magnitudes of the hydrodynamic forces generated by their driving stroke.

  2. Activated Random Walkers: Facts, Conjectures and Challenges

    NASA Astrophysics Data System (ADS)

    Dickman, Ronald; Rolla, Leonardo T.; Sidoravicius, Vladas

    2010-02-01

    We study a particle system with hopping (random walk) dynamics on the integer lattice ℤ d . The particles can exist in two states, active or inactive (sleeping); only the former can hop. The dynamics conserves the number of particles; there is no limit on the number of particles at a given site. Isolated active particles fall asleep at rate λ>0, and then remain asleep until joined by another particle at the same site. The state in which all particles are inactive is absorbing. Whether activity continues at long times depends on the relation between the particle density ζ and the sleeping rate λ. We discuss the general case, and then, for the one-dimensional totally asymmetric case, study the phase transition between an active phase (for sufficiently large particle densities and/or small λ) and an absorbing one. We also present arguments regarding the asymptotic mean hopping velocity in the active phase, the rate of fixation in the absorbing phase, and survival of the infinite system at criticality. Using mean-field theory and Monte Carlo simulation, we locate the phase boundary. The phase transition appears to be continuous in both the symmetric and asymmetric versions of the process, but the critical behavior is very different. The former case is characterized by simple integer or rational values for critical exponents ( β=1, for example), and the phase diagram is in accord with the prediction of mean-field theory. We present evidence that the symmetric version belongs to the universality class of conserved stochastic sandpiles, also known as conserved directed percolation. Simulations also reveal an interesting transient phenomenon of damped oscillations in the activity density.

  3. On the Move with the Waukesha Walkers.

    ERIC Educational Resources Information Center

    Gissal, Mary L.; Ray, Robert O.

    1981-01-01

    As part of a research study, a fitness trail was designed for older adults to increase their physical fitness and cardiovascular health. Exercise stations placed at quarter-mile intervals introduced exercises effective in improving flexibility, muscular strength, endurance, balance, and coordination. (JN)

  4. Transtensional Analyses of Fault Patterns and Strain Provinces of the Eastern California Shear Zone-Walker Lane on the Eastern Margin of the Sierra Nevada Microplate, California and Nevada

    NASA Astrophysics Data System (ADS)

    Taylor, T. R.; Dewey, J. F.

    2008-12-01

    Substantial work on the theory of transtensional strain at various scales has shown that transtension produces triaxial non-plane constrictional strains. At the plate boundary scale, fault geometries predicted by transtensional theory better explain observed fault patterns in the transtensional Eastern California shear zone-Walker Lane than 2D plane strain pure or simple shear solutions. Seemingly heterogeneous fault patterns and strain styles within structural provinces along the higher strain corridor adjacent to the eastern Sierra Nevada microplate margin are reconciled by non-plane strain evaluation, and in the context of triaxial, 3D strain partitioning characteristic of transtensional deformation. Among these structural provinces, which include the Honey Lake-Pyramid Lake region, the Lake Tahoe region, the Mono Lake-Long Valley region, Owens Valley, and the Coso region, all are found to be undergoing coaxially dominated transtension, except for the Mono Lake-Long Valley region which has possibly formed by noncoaxially dominated strain, and the northern Honey Lake-Pyramid Lake region, where the Sierra Nevada microplate boundary zone curves west toward the Mendocino triple junction. The local geometry of the transtensional zone boundary and the microplate transport direction determine the dominant type of non-plane strain. Fault orientations predicted by application of transtensional theory to identify instantaneous strain axes are consistent with those observed in each structural province, and comparatively, are not adequately explained by plane strain kinematic models. The orientations and amount of shortening and elongation of the finite strain ellipsoid axes for each province indicate smaller amounts of shortening, elongation and rotation of axes, and overall less ellipticity, in the coaxially dominated strain areas, and greater shortening, elongation, and rotation, and overall greater ellipticity, in the noncoaxially dominated areas. Exceptions are the

  5. Maps showing distribution of iron, cobalt, barium, strontium, arsenic, antimony, and bismuth in samples of minus-60-mesh (0.25-MM) stream sediment and (or) nonmagnetic heavy-mineral concentrate, Walker Lake 1 degree by 2 degrees Quadrangle, California and Nevada

    USGS Publications Warehouse

    Chaffee, M.A.; Hill, R.H.; Sutley, S.J.

    1988-01-01

    This report is part of a folio of maps of the Walker Lake 1o x 2o quadrangle, California and Nevada, prepared under the Conterminous United States Mineral Assessment Program. The folio includes geological, geochemical, and geophysical maps, as well as mineral resources assessment maps, which identify selected known or possible mineral-deposit environments in the quadrangle. The geochemical maps show the distributions of selected individual elements (Chaffee and others, 1988 a, b, c) and the distributions of selected groups of elements (Chaffee, 1988a, b, c). Discussions accompanying the individual element maps are restricted to mineral residences of the individual elements as well as to what types of mineral deposits and environments may be represented by anomalies of a particular element. Discussions accompanying the multielemental maps describe the types of mineral deposits that may be related to each element group and indicate the most favorable localities for these deposits. 

  6. 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... force gauges used for testing: (ii) 4.6.1Equipment—Force gauge with a range of 0 to 25 lbf (110 N), tolerance of ± 0.25 lbf (1.1 N). A calibration interval shall be maintained for the force guage which...

  7. 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

  8. College Orientation: Three Themes from Alice Walker's "The Color Purple."

    ERIC Educational Resources Information Center

    Osborne, Nancy Seale

    These four papers by a reference librarian discuss the potential for students at the State University of New York (SUNY) at Oswego to engage in a positive academic career that will have a significant impact not only on their growth as people, but also on their future endeavors. The first paper, "Self-Definition: Naming Yourself in a College…

  9. Dynamics of Robertson–Walker spacetimes with diffusion

    SciTech Connect

    Alho, A.; Calogero, S.; Machado Ramos, M.P.; Soares, A.J.

    2015-03-15

    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 directions and which undergo accelerated expansion at all times.

  10. A stochastic model of randomly accelerated walkers for human mobility.

    PubMed

    Gallotti, Riccardo; Bazzani, Armando; Rambaldi, Sandro; Barthelemy, Marc

    2016-01-01

    Recent studies of human mobility largely focus on displacements patterns and power law fits of empirical long-tailed distributions of distances are usually associated to scale-free superdiffusive random walks called Lévy flights. However, drawing conclusions about a complex system from a fit, without any further knowledge of the underlying dynamics, might lead to erroneous interpretations. Here we show, on the basis of a data set describing the trajectories of 780,000 private vehicles in Italy, that the Lévy flight model cannot explain the behaviour of travel times and speeds. We therefore introduce a class of accelerated random walks, validated by empirical observations, where the velocity changes due to acceleration kicks at random times. Combining this mechanism with an exponentially decaying distribution of travel times leads to a short-tailed distribution of distances which could indeed be mistaken with a truncated power law. These results illustrate the limits of purely descriptive models and provide a mechanistic view of mobility. PMID:27573984

  11. 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,…

  12. Passive walker that can walk down steps: simulations and experiments

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Li, Junfeng; Wang, Tianshu

    2008-10-01

    A planar passive walking model with straight legs and round feet was discussed. This model can walk down steps, both on stairs with even steps and with random steps. Simulations showed that models with small moments of inertia can navigate large height steps. Period-doubling has been observed when the space between steps grows. This period-doubling has been validated by experiments, and the results of experiments were coincident with the simulation.

  13. Myopic random walkers and exclusion processes: Single and multispecies

    NASA Astrophysics Data System (ADS)

    Landman, Kerry A.; Fernando, Anthony E.

    2011-10-01

    A motility mechanism based on a simple exclusion process, where the probability of movement of an agent depends on the number of unoccupied nearest-neighbor sites is considered. Such interacting agents are termed myopic. This problem is an extension of the famous blind or myopic ant in a labyrinth problem. For the interacting agent models considered here, each agent plays the role of an ant in a labyrinth, where the paths of allowed sites though the labyrinth consist of sites not occupied by other agents. We derive a nonlinear diffusion equation for the average occupancy of the discrete agent-based model for myopic agents. In contrast, interacting blind agents have a constant probability of movement to each of their nearest-neighbor sites, giving rise to a linear diffusion equation. Insight into the various terms in the nonlinear diffusion coefficient is obtained from a study of multiple subpopulations of interacting myopic agents, where an advection-diffusion equation for each subpopulation is derived, and from tracking an individual agent within the crowd, where a motility coefficient is extracted. Averaged discrete simulation data compares very well with the solution to the continuum models. We also compare the behavior of myopic and blind agents. The myopic motility mechanism is biologically motivated to emulate information an individual cell gathers from environment cues. The multispecies model developed and investigated here assists with the interpretation of experimental data involving the tracking subpopulations of cells within a total cell population.

  14. 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.

  15. 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

  16. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... friction = 0.05 NCAMI w/vest = Normal force (for CAMI dummy fitted with weighted vest scenario) = Measured....C. 552(a) and 1 CFR part 51. You may obtain a copy from ASTM International, 100 Bar Harbor Drive, P... platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI dummy Wwalker = Weight of...

  17. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... friction = 0.05 NCAMI w/vest = Normal force (for CAMI dummy fitted with weighted vest scenario) = Measured....C. 552(a) and 1 CFR part 51. You may obtain a copy from ASTM International, 100 Bar Harbor Drive, P... platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI dummy Wwalker = Weight of...

  18. 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...

  19. 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...

  20. 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.