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Sample records for versigonalia ruficauda walker

  1. Host-seeking behavior in larvae of the robber fly Mallophora ruficauda (Diptera: Asilidae).

    PubMed

    Castelo, Marcela K; Lazzari, Claudio R

    2004-04-01

    The robber fly Mallophora ruficauda is the most important pest of apiculture in the Pampas region of Argentina. Adults prey on honeybees and other insects, while larvae parasitize larvae of scarab beetles, which live underground. Females of M. ruficauda do not search for hosts but instead lay eggs in tall pastures. Once hatched, larvae drop to the ground and burrow underground to search for their hosts. We tested in the laboratory whether larvae of M. ruficauda actively search for their hosts using host and/or host-related chemical cues. We report that M. ruficauda detects its host using chemical cues that originate in the posterior half of the host's body, most likely from an abdominal exocrine structure. This particular host-searching strategy is described for the first time in Asilidae. PMID:15081826

  2. 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

  3. 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

  4. 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.

  5. 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 ...

  6. Host specificity in the host-seeking larva of the dipteran parasitoid Mallophora ruficauda and the influence of age on parasitism decisions.

    PubMed

    Barrantes, M E; Castelo, M K

    2014-06-01

    Larvae of the robber fly Mallophora ruficauda are ectoparasitoids of white grubs and adults are an important apiculture pest in Argentina. Females oviposit on tall grasses and the second instar larva actively searches and locates hosts. There are nine potential hosts in the distribution area of this parasitoid and Cyclocephala signaticollis (Coleoptera: Scarabaeidae) is the most parasitized in the field. However, M. ruficauda has a certain degree of behavioural flexibility towards different host species, and not being a strict specialist. The conditions under which the parasitoid orientates and accepts different hosts' species are unknown. We studied the host specificity of M. ruficauda towards three species of Cyclocephala genus and we determined whether this specificity depends on larval age. We also evaluated whether larva orientation towards Cyclocephala species changes with chemical cue concentration. We assessed host specificity measuring the orientation and acceptance behaviours towards kairomones extracts and live individuals of Cyclocephala species using M. ruficauda larvae of low and high life expectancy (i.e., young and aged second instar larvae). We observed that young larvae orientated only towards C. signaticollis chemical stimulus, whereas aged larvae orientated also towards C. modesta, and the same was observed with increasing stimuli's concentration. Both young and aged M. ruficauda larvae orientate towards live C. signaticollis and C. putrida species and rejected C. modesta. Also, we found that larvae accepted all Cyclocephala hosts. In conclusion, our results indicate that specificity in the laboratory, observed through host orientation and host acceptance behaviours, depends not only on the availability of host species, but also on the nature of the host's stimuli combined with parasitoid age. PMID:24548616

  7. 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.

  8. Joseph (Joe) A. Walker

    NASA Technical Reports Server (NTRS)

    1956-01-01

    In March 1945 Joseph A. Walker joined the National Advisory Committee for Aeronautics' Aircraft Engine Research Laboratory, Cleveland, Ohio, (later NASA's Lewis Research Center, now the Glenn Research Center) as a physicist. He transferred to the NACA High-Speed Flight Research Station, Edwards, California in 1951, as a research pilot. For the next fifteen years Walker served as a pilot at the Edwards flight research facility (today known as NASA's Dryden Flight Research Center) on such projects as the Bell X-1#2 (2 flights, first on August 27, 1951), Bell X-1A (1 flight on July 20, 1955), X-1E (21 flights, first on December 12, 1955), Douglas D-558-I #3 Skystreak (14 flights, first on June 29, 1951), Douglas D-558-II #2 Skyrocket (3 flights, first on April 29, 1955), Douglas D-558-II #3 Skyrocket (2 flights, first on May 7, 1954). On the Douglas X-3, Joe was project pilot and made all 20 flights, the first on August 1, 1954. Joe considered this aircraft the 'worst' plane he ever flew. He flew the Northrup X-4 (2 flights, first on October 18, 1951), Bell X-5 (78 flights, first on January 9, 1952). He also flew programs involving the F-100, F-101, F-102, F-104 and the B-47. Walker made the first NASA flight on the North American X-15 on March 25, 1960. His 25th and final X-15 flight on August 22, 1963, reached 354,200 feet, an unofficial record altitude of almost 67 miles. On October 30, 1964, Walker took the first Bell Lunar Landing Research Vehicle (LLRV) on its maiden flight, reaching a peak altitude of 10 feet and a free flight time of just under one minute. Two LLRV's and three Lunar Landing Training Vehicles developed from them were used to develop piloting and operational techniques for lunar landings. In November, he left the program after 35 flights on the first LLRV. Walker flew chase flights as well as research flights. On June 8, 1966 he was flying chase in NASA's F-104N for the Air Force's experimental bomber, North American XB-70A, when he was fatally injured in a mid-air collision between the planes. Joe graduated from Washington and Jefferson College in 1942, with a Bachelors degree in Physics. He enrolled in the civilian pilot training program in 1941 and, after graduation from college, entered the Army Air Forces. During World War II he flew P-38 fighters and F-5A photo reconnaissance for the Air Force, earning the Distinguished Flying Cross and the Air Medal with Seven Oak Clusters. Walker was a charter member of the Society of Experimental Test Pilots and one of the first to be designated a Fellow. He was honored with the Robert J. Collier Trophy, the Harmon International Trophy for Aviators, the Iven C. Kincheloe Award and the Octave Chanute Award, all in 1961. He received an honorary Doctor of Aeronautical Sciences degree from his alma mater in June of 1961 and was named Pilot of the Year in 1963 by the National Pilots Association. Joseph Albert Walker was born February 20, 1921, in Washington, Pennsylvania; he died on June 8, 1966 at Edwards, California.

  9. 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

  10. Intelligently Controllable Walker with Magnetorheological Fluid Brake

    NASA Astrophysics Data System (ADS)

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

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

  11. 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.

  12. Abstract models of molecular walkers

    NASA Astrophysics Data System (ADS)

    Semenov, Oleg

    Recent advances in single-molecule chemistry have led to designs for artificial multi-pedal walkers that follow tracks of chemicals. The walkers, called molecular spiders, consist of a rigid chemically inert body and several flexible enzymatic legs. The legs can reversibly bind to chemical substrates on a surface, and through their enzymatic action convert them to products. We study abstract models of molecular spiders to evaluate how efficiently they can perform two tasks: molecular transport of cargo over tracks and search for targets on finite surfaces. For the single-spider model our simulations show a transient behavior wherein certain spiders move superdiffusively over significant distances and times. This gives the spiders potential as a faster-than-diffusion transport mechanism. However, analysis shows that single-spider motion eventually decays into an ordinary diffusive motion, owing to the ever increasing size of the region of products. Inspired by cooperative behavior of natural molecular walkers, we propose a symmetric exclusion process (SEP) model for multiple walkers interacting as they move over a one-dimensional lattice. We show that when walkers are sequentially released from the origin, the collective effect is to prevent the leading walkers from moving too far backwards. Hence, there is an effective outward pressure on the leading walkers that keeps them moving superdiffusively for longer times. Despite this improvement the leading spider eventually slows down and moves diffusively, similarly to a single spider. The slowdown happens because all spiders behind the leading spiders never encounter substrates, and thus they are never biased. They cannot keep up with leading spiders, and cannot put enough pressure on them. Next, we investigate search properties of a single and multiple spiders moving over one- and two-dimensional surfaces with various absorbing and reflecting boundaries. For the single-spider model we evaluate by how much the slowdown on newly visited sites, owing to catalysis, can improve the mean first passage time of spiders and show that in one dimension, when both ends of the track are an absorbing boundary, the performance gain is lower than in two dimensions, when the absorbing boundary is a circle; this persists even when the absorbing boundary is a single site. Next, we study how multiple molecular spiders influence one another during the search. We show that when one spider reaches the trace of another spider it is more likely not to follow the trace and instead explore unvisited sites. This interaction between the spiders gives them an advantage over independent random walkers in a search for multiple targets. We also study how efficiently the spiders with various gaits are able to find specific targets. Spiders with gaits that allow more freedom of leg movement find their targets faster than spiders with more restrictive gaits. For every gait, there is an optimal detachment rate that minimizes the time to find all target sites.

  13. How effective are brakes on infant walkers?

    PubMed

    Ridenour, M V

    1997-06-01

    62 children, between the ages of 9 and 18 months old, were observed in an instrumented walker to measure the peak horizontal pull forces. These pull forces were later used to evaluate an infant walker with a braking system that would stop on the top step of the stairs before falling down the stairs. This brake system is activated when part of the walker crosses over the edge of the top step. Using the range of horizontal pull forces generated by the 62 children, the horizontal brake system for walkers would not always prevent the walker from falling down the stairs. Four floor surfaces were compared: carpet, vinyl, glossy wood, and unfinished wood. The walker brake system did not always stop the walkers on these floor surfaces. Using the measured weights and horizontal forces of the 21 nonwalking children between 9 and 13 months old who represent children who typically fall down the stairs in a walker, a simulation procedure was completed to represent the worse possible force condition, the peak horizontal force, for each of the 21 children. During this simulation, brakes would have failed all the time for 18 of the 21 children, and at least half the time for the remaining 3 children. These brake systems may provide false security to parents who use these walkers, since there are no published standards regarding the performance of brake systems for infant walkers as a safety device. PMID:9172223

  14. 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

  15. Walker Branch Watershed Ecosystems Data

    DOE Data Explorer

    These projects have all contributed to a more complete understanding of how forest watersheds function and have provided insights into the solution of energy-related problems associated with air pollution, contaminant transport, and forest nutrient dynamics. This is one of a few sites in the world characterized by long-term, intensive environmental studies. The Walker Branch Watershed website at http://walkerbranch.ornl.gov/ provides maps, photographs, and data on climate, precipitation, atmospheric deposition, stream discharge and runoff, stream chemistry, and vegetation. [Taken from http://walkerbranch.ornl.gov/ABOUTAAA.HTM

  16. 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....

  17. 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....

  18. 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....

  19. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  20. 21 CFR 890.3825 - Mechanical walker.

    Code of Federal Regulations, 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....

  1. 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.

  2. Genetics Home Reference: Dandy-Walker malformation

    MedlinePLUS

    ... right halves of the brain (agenesis of the corpus callosum), a sac-like protrusion of the brain through ... Walker malformation? agenesis ; atresia ; brainstem ; cell ; cerebellum ; chromosome ; corpus callosum ; diabetes ; disabilities ; disability ; fetus ; gait ; hydrocephalus ; hypoplasia ; imaging ; ...

  3. Active faulting in the Walker Lane

    NASA Astrophysics Data System (ADS)

    Wesnousky, Steven G.

    2005-06-01

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

  4. Baby walkers . . . time to take a stand?

    PubMed Central

    Gleadhill, D N; Robson, W J; Cudmore, R E; Turnock, R R

    1987-01-01

    Experience in our hospital and figures from the Home Accident Surveillance System indicate that the number of accidents involving baby walkers is increasing. Safety specifications issued by the British Standards Institution are rarely, if ever, met in full by manufacturers. Home accident prevention measures have been shown to be of limited benefit. We advocate more stringent implementation of safety features in the design of baby walkers. Images Fig. 1 Fig. 2 Fig. 3 PMID:3606183

  5. 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.

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

    PubMed

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

    1993-01-01

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

  7. Soils of Walker Branch Watershed

    SciTech Connect

    Lietzke, D.A.

    1994-01-01

    The soil survey of Walker Branch Watershed (WBW) utilized the most up-to-date knowledge of soils, geology, and geohydrology in building the soils data base needed to reinterpret past research and to begin new research in the watershed. The soils of WBW were also compared with soils mapped elsewhere along Chestnut Ridge on the Oak Ridge Reservation to (1) establish whether knowledge obtained elsewhere could be used within the watershed, (2) determine whether there were any soils restricted to the watershed, and (3) evaluate geologic formation lateral variability. Soils, surficial geology, and geomorphology were mapped at a scale of 1:1200 using a paper base map having 2-ft contour intervals. Most of the contours seemed to reasonably represent actual landform configurations, except for dense wooded areas. For example, the very large dolines or sinkholes were shown on the contour base map, but numerous smaller ones were not. In addition, small drainageways and gullies were often not shown. These often small but important features were located approximately as soil mapping progressed. WBW is underlain by dolostones of the Knox Group, but only a very small part of the surface area contains outcroppings of rock and most outcrops were located in the lower part. Soil mapping revealed the presence of both ancient alluvium and ancient colluvium deposits, not recognized in previous soil surveys, that have been preserved in high-elevation stable portions of present-day landforms. An erosional geomorphic process of topographic inversion requiring several millions of years within the Pleistocene is necessary to bring about the degree of inversion that is expressed in the watershed. Indeed, some of these ancient alluvial and colluvial remnants may date back into the Tertiary. Also evident in the watershed, and preserved in the broad, nearly level bottoms of dolines, are multiple deposits of silty material either devoid or nearly devoid of coarse fragments. Recent research indicates that most of this silty material is the result of slope wash processed during the Holocene Age. Residual soils of the watershed were related to the underlying geologic formations by their morphology and types of chert. Colluvial soils were identified and mapped whenever the colluvium thickness exceeded 20 in. (50 cm). Except for the ancient colluvial soils (colluvium without a present-day source area), colluvial soils were not separated according to their geologic age, but stacked colluvial deposits are located in low footslope landforms. Colluvial soils in the watershed were identified and mapped according to their morphologic properties that would influence the perching and subsurface movement of water. Alluvial soils were restricted to present floodplains, low fan terraces, and low fan deltas. Nearly all alluvial soils contained very young surficial sediments derived from slopewash resulting from land clearing and subsequent agricultural activities.

  8. Risks of Baby Walkers and Options for Prevention

    PubMed Central

    Aziz, Alnoor; McIntyre, Lynn; Khazen, Roch

    1985-01-01

    Recent studies have reported fatal head injuries associated with baby walkers. Skull fractures and hospital admissions are significantly higher for infants who have received head injuries while using a walker. Thirty to 50% of infants regularly placed in walkers experience an accident or injury related to the device. Most injuries are minor cuts, abrasions and contusions. While there are many hazards, no benefits have been documented. The walkers do not help children learn to walk. Options for preventing injury including banning baby walkers, product design regulations, and public education about the risks. An outright ban would be difficult, because walkers are not considered inherently dangerous; they become so when parental supervision is lacking. Although design specifications will decrease some walker-related injuries, they will not prevent severe or fatal head injuries associated with falls down stairs. Public awareness of hazards from baby walkers and discouragement of their use are recommended preventive measures at this time. PMID:21274133

  9. 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

  10. 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

  11. Perioperative considerations in WalkerWarburg syndrome

    PubMed Central

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

    2015-01-01

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

  12. 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…

  13. 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

  14. 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…

  15. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....C. 552(a) and 1 CFR part 51. You may obtain a copy from ASTM International, 100 Bar Harbor Drive, P... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Requirements for infant walkers. 1216.2... REGULATIONS SAFETY STANDARD FOR INFANT WALKERS 1216.2 Requirements for infant walkers. (a) Except...

  16. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... by reference listed in this section in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. You may... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Requirements for infant walkers. 1216.2... REGULATIONS SAFETY STANDARD FOR INFANT WALKERS 1216.2 Requirements for infant walkers. Each infant...

  17. 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.

  18. Obituary: Robert Mowbray Walker, 1929-2004

    NASA Astrophysics Data System (ADS)

    Schoenherr, Neil T.

    2004-12-01

    Robert M. Walker, PhD, Professor of Physics in Arts & Sciences and a faculty fellow of the McDonnell Center for the Space Sciences, died of stomach cancer Thursday, 12 February 2004, in Brussels, Belgium. He was 75. Walker worked on the frontiers of space research for more than four decades. Robert Walker was born in Philadelphia on 6 February 1929. His mother was Dorothy Potter and he considered Roger Potter his father though he was not his biological father. His early years were spent in New York City and in upstate New York. He attended the Bronx High School of Science, earned his BS in physics from Union College and in 1954, he received his PhD in particle physics from Yale University. He subsequently joined the General Electric Laboratory in Schenectady, New York where he studied the radiation effects in solids. His work on defects in irradiated copper is still regarded as the definitive work on the topic. In the early 1960s, Walker's discovery of fossil nuclear particle tracks in minerals was instrumental to new developments in geo-chronology and cosmic ray physics. In particular, his discovery of tracks from nuclei heavier than iron opened a new frontier of cosmic ray physics. He subsequently pioneered the use of plastics to detect and count such nuclei in cosmic ray balloon flights. Beginning in 1966, when he moved to Washington University and became the first McDonnell Professor of Physics, his research interests turned more toward space physics. He was the inaugural director of the McDonnell Center, which was established in 1975 by a gift from aerospace pioneer James S. McDonnell. Walker was a member of the NASA committee that allocated samples of the first returned lunar materials, and his laboratory led the way in deciphering their record of lunar, solar system and galactic evolution. Together with Ghislaine Crozaz and other colleagues, Walker made path breaking laboratory studies of the first moon rocks revealing the history of solar radiation and cosmic rays within these samples. He and Dr. Crozaz were married in 1973. In the past two decades, he was a world leader of microanalytical studies of tiny grains preserved for eons in meteorites, culminating in their identification as stardust. More recent achievements include the design of micrometeorite capture cells that were flown aboard NASA's Long Duration Exposure Facility; verification of the extraterrestrial origin of dust particles collected in the upper atmosphere; and the successful search for interstellar grains in meteorites. "Bob was such a dominant force for excellence in our department and the University over so many years, it is hard to grasp that he is gone," said John W. Clark, PhD, chair of physics, the Wayman Crow Professor and a faculty fellow of the McDonnell Center. "His passion for life and science was an inspiration to us all, and his legacy will endure in the work of his many colleagues and the extended family of his former students." Walker led the McDonnell Center, which includes one of the world's largest research groups dedicated to the search for and investigation of extraterrestrial materials, until 1999. "Washington University would be a lesser institution without the contributions of Bob Walker," said William H. Danforth, chancellor emeritus and vice chairman of the Board of Trustees. "He gave us inspiration, enthusiasm, great science and visionary leadership. He built the strength of the McDonnell Center for the Space Sciences. He convinced others of the potential for the modern Department of Earth and Planetary Sciences. He had always the respect and affection of us all." The last two decades of Walker's career were driven by his remarkable vision and his excitement at the prospect of profound discovery. His recognition of the potential importance of the ion microprobe for making isotopic measurements on microscopic samples, and his acquisition in 1982 of a state-of-the-art instrument for the University, led directly to a series of spectacular results. Chief among these was the identification and characterization of stellar condensates in meteorites, which opened a window into stellar evolution and the creation of the heavier elements. Always in pursuit of more powerful ways to analyze small amounts of material, Walker devoted the last years of his life to the implementation of nanoscale secondary-ion mass spectrometry (NanoSIMS) promoting the development, acquisition and application of the most advanced instrument of its kind. This effort was rewarded with the discovery, which he had forecast years earlier, of presolar silicate grains in interplanetary dust particles. The Robert M. Walker Symposium at the University in March 2003 honored his contributions and achievements. He was elected to the National Academy of Sciences in 1973. Among his other honors are the E.O. Lawrence Memorial Award of the U.S. Atomic Energy Commission, the J. Lawrence Smith medal of the National Academy of Sciences, the Leonard medal of the Meteoritical Society and the Antarctic Service Medal. He received honorary doctorates from Union College (1967), the French University of Clermont-Ferrand (1975) and Washington University (2004). He was also one of the founders, and first president, of VITA (Volunteers in Technical Assistance), an organization that provides technological expertise to third world countries. Walker and his wife maintained a residence in St. Louis County but in 2001, Bob became a part time visiting professor at the University of Brussels. It was in Brussels that his fatal illness was correctly diagnosed. In addition to his wife, Walker is survived by his sons, Eric and Mark Walker; and three grandchildren. His most important legacy will remain the sizable number of students, postdocs, and colleagues within the meteoritic and cosmochemist communities that he mentored and inspired. Portions of this obituary are based upon one given in the on-line Record of Washington University and another published by Floss, Sandford and Zinner in Meteoritics and Planetary Science (39:1409-1411, 2004).

  19. 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 precipitation of calcium carbonate, which is trapped and bound by an understory of green and blue-green algae. The occurrence of stromatolites in highly siliciclastic lakes seems to be restricted to shoreline and nearshore environments, and can be used to locate ancient lake margins.

  20. 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

  1. Space Walker - the Cognitive Visualization System

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  2. DNA machines: bipedal walker and stepper.

    PubMed

    Wang, Zhen-Gang; Elbaz, Johann; Willner, Itamar

    2011-01-12

    The assembly of a "bipedal walker" and of a "bipedal stepper" using DNA constructs is described. These DNA machines are activated by H(+)/OH(-) and Hg(2+)/cysteine triggers. The bipedal walker is activated on a DNA template consisting of four nucleic acid footholds. The forward "walking" of the DNA on the template track is activated by Hg(2+) ions and H(+) ions, respectively, using the thymine-Hg(2+)-thymine complex or the i-motif structure as the DNA translocation driving forces. The backward "walking" is activated by OH(-) ions and cysteine, triggers that destroy the i-motif or thymine-Hg(2+)-thymine complexes. Similarly, the "bipedal stepper" is activated on a circular DNA template consisting of four tethered footholds. With the Hg(2+)/cysteine and H(+)/OH(-) triggers, clockwise or anticlockwise stepping is demonstrated. The operation of the DNA machines is followed optically by the appropriate labeling of the walker-foothold components with the respective fluorophores/quenchers units. PMID:21166467

  3. 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

  4. 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.

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

    PubMed

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

    2015-01-01

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

  6. A review of the functionalities of smart walkers.

    PubMed

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

    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

  7. 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

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

    PubMed Central

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

    2015-01-01

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

  9. 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 60year 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

  10. 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

  11. Interacting walkers on the Cayley tree, and polymer statistics

    SciTech Connect

    Priezzhev, V.B.

    1986-09-01

    We obtain the generating function for an ensemble of random walkers on the Cayley tree of coordination number z. The pair interaction between walkers is taken into account. This forbids two walkers to occupy the same lattice point after an equal number of steps. Interacting polymer statistics results from this model if one associates time (or the number of steps) with an additional space coordinate. The limiting free energy appears in a form that corresponds to the phase transition of ''3/2 order.''

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

    NASA Technical Reports Server (NTRS)

    1952-01-01

    This photo shows test pilots, (Left-Right) Joseph A. Walker, Stanley P. Butchart and Walter P. Jones, standing in front of the Douglas D-558-II Skystreak, in 1952. These three test pilots at the National Advisory Committee for Aeronautics' High-Speed Flight Research Station probably were discussing their flights in the aircraft. Joe flew research flights on the D-558-I #3 (14 flights, first on June 29, 1951) investigating buffeting, tail loads, and longitudinal stability. He flew the D-558-II #2 (3 flights, first on April 29, 1955) and recorded data on lateral stability and control. He also made pilot check-out flights in the D-558-II #3 (2 flights, first on May 7, 1954). For fifteen years Walker served as a pilot at the Edwards flight research facility (today known as the National Aeronautics and Space Administration's Dryden Flight Research Center) on research flights as well as chase missions for other pilots on NASA and Air Force research programs. On June 8, 1966, he was flying chase in NASA's F-104N for the Air Force's experimental bomber, North American XB-70A, when he was fatally injured in a mid-air collision between the planes. Stan flew the D-558-I #3 (12 flights, first on October 19, 1951) to determine the dynamic longitudinal stability characteristics and investigations of the lateral stability and control. He made one flight in the D-558-II #3 on June 26, 1953, as a pilot check-out flight. Butchart retired from the NASA Dryden Flight Research Center at Edwards, California, on February 27, 1976, after a 25-year career in research aviation. Stan served as a research pilot, chief pilot, and director of flight operations. Walter P. Jones was a research pilot for NACA from the fall of 1950 to July 1952. He had been in the U.S. Air Force as a pilot before joining the Station. Jones flew the D-558-I #3 (5 flights, first on February 13, 1951) to study buffeting, tail loads and longitudinal stability. Jones made research flights on the D-558-II #3 ( 7 flights, first on July 20, 1951). These flights investigated pitch-up and evaluated outboard wing fences. Walt also made research flights in the Northrop X-4 (14 flights, first on March 26, 1952) and the Bell X-5 (8 flights, first on June 20, 1952). In July 1952, Walt left NACA's High-Speed Flight Research Station to join Northrop Corporation as a pilot. Returning from a test mission in a Northrop YF-89D Scorpion he was fatally injured on October 20, 1953, near Edwards Air Force Base.

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

    ERIC Educational Resources Information Center

    Chapman, Judith D.

    1995-01-01

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

  14. Interaction of two walkers: Wave-mediated energy and force

    NASA Astrophysics Data System (ADS)

    Borghesi, Christian; Moukhtar, Julien; Labousse, Matthieu; Eddi, Antonin; Fort, Emmanuel; Couder, Yves

    2014-12-01

    A bouncing droplet, self-propelled by its interaction with the waves it generates, forms a classical wave-particle association called a "walker." Previous works have demonstrated that the dynamics of a single walker is driven by its global surface wave field that retains information on its past trajectory. Here we investigate the energy stored in this wave field for two coupled walkers and how it conveys an interaction between them. For this purpose, we characterize experimentally the "promenade modes" where two walkers are bound and propagate together. Their possible binding distances take discrete values, and the velocity of the pair depends on their mutual binding. The mean parallel motion can be either rectilinear or oscillating. The experimental results are recovered analytically with a simple theoretical framework. A relation between the kinetic energy of the droplets and the total energy of the standing waves is established.

  15. STS-69 Mission Commander David M. Walker arrives at SLF

    NASA Technical Reports Server (NTRS)

    1995-01-01

    STS-69 Mission Commander David M. Walker arrives at KSC's Shuttle Landing Facility. Walker and four fellow crew members flew in from Johnson Space Center, Houston in the T-38 jet aircraft traditionally used by the astronaut corps. Later today, the countdown will begin as final preparations continue toward liftoff of the Space Shuttle Endeavour at 11:04 a.m. EDT, August 31 on STS-69.

  16. STS-69 Mission Commander David M. Walker suits up

    NASA Technical Reports Server (NTRS)

    1995-01-01

    STS-69 Mission Commander David M. Walker signals he's ready to fly as he finishes donning his launch/entry suit in the Operations and Checkout Building. Walker, who is embarking on his fourth trip into space, will depart shortly for Launch Pad 39A along with four fellow crew members. Awaiting the crew and liftoff at 11:09 a.m. EDT is the Space Shuttle Endeavour.

  17. 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.

  18. 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

  19. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946. On Oct. 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system of increased capacity, and a thinner high-speed wing. The X-1E was used to obtain in-flight data at twice the speed of sound, with particular emphasis placed on investigating the improvements achieved with the high-speed wing. These wings, made by Stanley Aircraft, were only 3 3/8-inches thick at the root and had 343 gauges installed in them to measure structural loads and aerodynamic heating. The X-1E used its rocket engine to power it up to a speed of 1,471 miles per hour (Mach 2.24) and to an altitude of 73,000 feet. Like the X-1 it was air-launched. The X-1 aircraft were almost 31 feet long and had a wingspan of 28 feet. The X-1 was built of conventional aluminum stressed-skin construction to extremely high structural standards. The X-1E was also 31 feet long but had a wingspan of only 22 feet, 10 inches. It was powered by a Reaction Motors, Inc., XLR-8-RM-5, four-chamber rocket engine. As did all X-1 rocket engines, the LR-8-RM-5 engine did not have throttle capability, but instead, depended on ignition of any one chamber or group of chambers to vary speed. The X-1A, X-1B, and the X-1D were growth versions of the X-1. They were almost five feet longer, almost 2,500 pounds heavier and had conventional canopies. The X-1A and X-1B were modified to have ejection seats. Their mission was to continue the X-1 studies at higher speeds and altitudes. The X-1A began this research after the X-1D was destroyed in an explosion on a captive flight before it made any research flights. On Dec. 12, 1953, Major Charles Yeager flew the X-1A up to a speed of 1,612 miles per hour (almost two-and-a-half times the speed of sound). Then on Aug. 26, 1954, Major Arthur Murray took the X-1A up to an altitude of 90,440 feet. Those two performances were the records for the X-1 program. Later the X-1A was also destroyed after being jettisoned from the carrier aircraft because of an explosion. The X-1B was fitted with 300 thermocouples for exploratory aerodynamic heating tests. installed on it. It also was the first aircraft to fly with a reaction control system, a prototype of the system used on the X-15. The X-1C was cancelled before production. All three of the Bell Aircraft Company-manufactured planes had 6,000-pound-thrust, XLR-11 four-chambered rocket engines. The XLR-11 was built by Reaction Motors, Inc. The aircraft were all air-launched from a carrier aircraft.

  20. X-1E with Pilot Joe Walker

    NASA Technical Reports Server (NTRS)

    1958-01-01

    A photo of the X-1E with pilot Joe Walker suited up at the NASA High-Speed Flight Station, Edwards, California. The dice and 'Little Joe' are prominently displayed under the cockpit area. (Little Joe is a dice players slang term for two deuces.) Five years later when Walker reached 354,200 feet in the X-15, that aircraft carried similar artwork - 'Little Joe the II.' Walker is shown in the photo above wearing an early partial pressure suit. This protected the pilot if cockpit pressure was lost above 50,000 feet. There were five versions of the Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Sonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on Jan. 25, 1946. Powered flights began in December 1946. On Oct. 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system of increased capacity, and a thinner high-speed wing. The X-1E was used to obtain in-flight data at twice the speed of sound, with particular emphasis placed on investigating the improvements achieved with the high-speed wing. These wings, made by Stanley Aircraft, were only 3 3/8-inches thick at the root and had 343 gauges installed in them to measure structural loads and aerodynamic heating. The X-1E used its rocket engine to power it up to a speed of 1,471 miles per hour (Mach 2.24) and to an altitude of 73,000 feet. Like the X-1 it was air-launched. The X-1 aircraft were almost 31 feet long and had a wingspan of 28 feet. The X-1 was built of conventional aluminum stressed-skin construction to extremely high structural standards. The X-1E was also 31 feet long but had a wingspan of only 22 feet, 10 inches. It was powered by a Reaction Motors, Inc., XLR-8-RM-5, four-chamber rocket engine. As did all X-1 rocket engines, the LR-8-RM-5 engine did not have throttle capability, but instead, depended on ignition of any one chamber or group of chambers to vary speed. The X-1A, X-1B, and the X-1D were growth versions of the X-1. They were almost five feet longer, almost 2,500 pounds heavier and had conventional canopies. The X-1A and X-1B were modified to have ejection seats. Their mission was to continue the X-1 studies at higher speeds and altitudes. The X-1A began this research after the X-1D was destroyed in an explosion on a captive flight before it made any research flights. On Dec. 12, 1953, Major Charles Yeager flew the X-1A up to a speed of 1,612 miles per hour (almost two-and-a-half times the speed of sound). Then on Aug. 26, 1954, Major Arthur Murray took the X-1A up to an altitude of 90,4

  1. Superdiffusive transport by multivalent molecular walkers moving under load

    NASA Astrophysics Data System (ADS)

    Olah, Mark J.; Stefanovic, Darko

    2013-06-01

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

  2. Walker Circulation, El Nio and La Nia

    NASA Astrophysics Data System (ADS)

    Halpern, D.

    2014-12-01

    Ocean surface wind vector is likely the critical variable to predict onset, maintenance and dissipation of El Nio and La Nia. Analyses of SeaWinds and ASCAT 10-m height (called "surface") vector winds in the Atlantic, Indian and Pacific Oceans from 1S-1N during March 2000 - June 2011 revealed the longitudinal distribution of the surface zonal wind component associated with the Walker Circulation. In the Pacific Ocean east of 140E and west of 85W, the mean wind direction was westward towards the maritime continent with maximum mean zonal wind speed (- 6.5 m s-1) at 150W; east of 85W the mean direction was toward the convection zone over South America. Four El Nios and five La Nias occurred from March 2000 - June 2011. In the Pacific from 150E to 160W, the average El Nio (La Nia) westward wind speed was 2 m s-1 (1 m s-1) smaller (larger) than normal. In the west Pacific, the variation in westward wind speeds in El Nio and La Nia conditions relative to normal conditions would be expected to substantially uplift the thermocline during El Nio compared to La Nia, which is consistent with conventional wisdom. In the east Pacific from 130W - 100W, average El Nio westward wind speeds were less than normal and La Nia conditions by 0.5 m s-1 and 1 m s-1, respectively. The "central" Pacific nature of the El Nios may have influenced the smaller difference between El Nio and La Nia westward wind speeds in the east Pacific compared to the west Pacific. Analyses of longitudinal distributions of thermocline depths will be discussed. Surface zonal wind speeds in the Atlantic and Indian Oceans showed no evidence of El Nio and La Nia; surface meridional winds showed an apparent response in the Indian and Pacific Oceans but not in the Atlantic Ocean. At 700-m height, the MISR zonal wind component in the Atlantic, Indian and Pacific Oceans had similar features as those at the surface, except in the east Pacific where the westward wind speeds were identical during El Nio, La Nia and normal conditions. In the east Pacific, the shear between 10- and 700-m heights increased (decreased) during La Nia (El Nio).

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

    NASA Astrophysics Data System (ADS)

    Bellomo, Katinka; Clement, Amy C.

    2015-09-01

    Climate models simulate a weakening of the Walker circulation in response to increased greenhouse gases, but it has not been possible to detect this weakening with observations because there are not direct measurements of atmospheric circulation strength. Indirect measurements, such as equatorial gradients in sea level pressure (SLP), exhibit trends of inconsistent sign. In this study we estimate the change in midtropospheric velocity (ω500) from observed change in cloud cover, which we argue is more closely tied to the overturning circulation than indirect measurements of SLP at the surface. Our estimates suggest a weakening and eastward shift of the Walker circulation over the last century. Because changes in cloud cover in Atmospheric Model Intercomparison Project simulations forced with increased sea surface temperature are remarkably similar in pattern, sign, and magnitude, we assert that the observed changes in cloud cover and the associated weakening of Walker circulation are at least in part externally forced.

  4. 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.

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

    PubMed

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

    2015-12-01

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

  6. 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.

  7. Dandy Walker Variant and Bipolar I Disorder with Graphomania

    PubMed Central

    Karaka? U?urlu, Grkem; akmak, Selcen

    2014-01-01

    Cerebellum is known to play an important role in coordination and motor functions. In some resent studies it is also considered to be involved in modulation of mood, cognition and psychiatric disorders. Dandy Walker Malformation is a congenital malformation that is characterized by hypoplasia or aplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle and enlargement of the posterior fossa. When the volume of posterior fossa is normal, the malformation is called Dandy Walker Variant. Case is a 32 year old male with a 12 year history of Bipolar I Disorder presented with manic and depresive symptoms, including dysphoric and depressive affect, anhedonia, suicidal thoughts and behaviours, thoughts of fear about future, overtalkativeness and graphomania, increased energy, irregular sleep, loss of appetite, increased immersion in projects, irritability, agressive behavior, impulsivity. Cranial Magnetic Resonance Imaging was compatible to the morphological features of Dandy Walker Variant. PMID:25110509

  8. 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

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

    NASA Astrophysics Data System (ADS)

    Schehr, Grgory; 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.

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

  11. Bathymetry of Walker Lake, West-Central Nevada

    USGS Publications Warehouse

    Lopes, Thomas J.; Smith, J. LaRue

    2007-01-01

    Walker Lake lies within a topographically closed basin in west-central Nevada and is the terminus of the Walker River. Much of the streamflow in the Walker River is diverted for irrigation, which has contributed to a decline in lake-surface altitude of about 150 feet and an increase in dissolved solids from 2,500 to 16,000 milligrams per liter in Walker Lake since 1882. The increase in salinity threatens the fresh-water ecosystem and survival of the Lahontan cutthroat trout, a species listed as threatened under the Endangered Species Act. Accurately determining the bathymetry and relations between lake-surface altitude, surface area, and storage volume are part of a study to improve the water budget for Walker Lake. This report describes the updated bathymetry of Walker Lake, a comparison of results from this study and a study by Rush in 1970, and an estimate of the 1882 lake-surface altitude. Bathymetry was measured using a single-beam echosounder coupled to a differentially-corrected global positioning system. Lake depth was subtracted from the lake-surface altitude to calculate the altitude of the lake bottom. A Lidar (light detection and ranging) survey and high resolution aerial imagery were used to create digital elevation models around Walker Lake. The altitude of the lake bottom and digital elevation models were merged together to create a single map showing land-surface altitude contours delineating areas that are currently or that were submerged by Walker Lake. Surface area and storage volume for lake-surface altitudes of 3,851.5-4,120 feet were calculated with 3-D surface-analysis software. Walker Lake is oval shaped with a north-south trending long axis. On June 28, 2005, the lake-surface altitude was 3,935.6 feet, maximum depth was 86.3 feet, and the surface area was 32,190 acres. The minimum altitude of the lake bottom from discrete point depths is 3,849.3 feet near the center of Walker Lake. The lake bottom is remarkably smooth except for mounds near the shore and river mouth that could be boulders, tree stumps, logs, or other submerged objects. The echosounder detected what appeared to be mounds in the deepest parts of Walker Lake, miles from the shore and river mouth. However, side-scan sonar and divers did not confirm the presence of mounds. Anomalies occur in two northwest trending groups in northern and southern Walker Lake. It is hypothesized that some anomalies indicate spring discharge along faults based on tufa-like rocks that were observed and the northwest trend parallel to and in proximity of mapped faults. Also, evaporation measured from Walker Lake is about 50 percent more than the previous estimate, indicating more water is flowing into the lake from sources other than the Walker River. Additional studies need to be done to determine what the anomalies are and whether they are related to the hydrology of Walker Lake. Most differences in surface area and storage volume between this study and a study by Rush in 1970 were less than 1 percent. The largest differences occur at lake-surface altitudes less than 3,916 feet. In general, relations between lake-surface altitude, surface area, and storage volume from Rush's study and this study are nearly identical throughout most of the range in lake-surface altitude. The lake-surface altitude in 1882 was estimated to be between 4,080 feet and 4,086 feet with a probable altitude of 4,082 feet. This estimate compares well with two previous estimates of 4,083 feet and 4,086 feet. Researchers believe the historic highstand of Walker Lake occurred in 1868 and estimated the highstand was between 4,089 feet and 4,108 feet. By 1882, Mason Valley was predominantly agricultural. The 7-26 feet decline in lake-surface altitude between 1868 and 1882 could partially be due to irrigation diversions during this time.

  12. 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...

  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. 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

  15. 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

  16. STS-69 Mission Commander David M. Walker returns to KSC

    NASA Technical Reports Server (NTRS)

    1995-01-01

    STS-69 Mission Commander David M. Walker and four fellow crew members return to KSC for a second launch try. The Space Shuttle Endeavour is scheduled for liftoff on Sept. 7 at 11:09 a.m. EDT, just about a week after the first try was scrubbed due to a faulty fuel cell.

  17. 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

  18. 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... walker Wdrop weight = Drop weight = 8 lb ?k = Dynamic coefficient of friction = 0.05 NCAMI = Normal force... Wdrop weight = Drop weight = 8 lb ?k = Dynamic coefficient of friction = 0.05 NCAMI w/vest =...

  19. 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

  20. 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.

  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. 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

  3. 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

  4. 16 CFR 1216.2 - Requirements for infant walkers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ....C. 552(a) and 1 CFR part 51. You may obtain a copy from ASTM International, 100 Bar Harbor Drive, P... section 7.6.2 of ASTM F 977-07, use the following table instead of Table 1 Summary of Step(s) Tests: (i... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Requirements for infant walkers....

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

    PubMed

    Olivier, Anne-Hlne; Marin, Antoine; Crtual, Armel; Berthoz, Alain; Pettr, Julien

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Dariescu, Ciprian; Dariescu, Marina-Aura

    2015-11-01

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

  7. 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))....

  8. 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...

  9. 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)

  10. 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 Rozkon and Koznek (2007). This is the first species of Culcua reported from Viet...

  11. 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...

  12. 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

  13. Study of the dynamic behaviour of a piezo-walker

    NASA Astrophysics Data System (ADS)

    Mariotto, G.; D'Angelo, M.; Kresnin, J.; Shvets, I. V.

    1999-04-01

    We have examined two configurations of a piezo-walker, the inertial one and the frictional one, both of which are capable of moving samples with submicrometer steps over a distance of some millimeters. We demonstrated that, contrary to expectations, operation of the frictional walker in which six piezos shear one by one, is still dependent on inertial slip-stick action. We studied the dependence of the step-size on the time delay between rising fronts applied to consecutive piezos and we found that the characteristic time associated with the minimum value of the step-size is of the order of the time of a sound wave propagating along the rod between the piezos.

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

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-10-01

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

  15. A first-passage time problem for many random walkers

    NASA Astrophysics Data System (ADS)

    Argyrakis, Panos; Weiss, George H.

    2006-05-01

    The passage of ions through membrane channels plays an important role in many fields of biology. An earlier paper [M. Boguñá, A.M. Berezhkovskii, G.H. Weiss, Phys. Rev. E 62 (2000) 3250] developed a toy model for statistical properties of the occupancy of a single site by different numbers of lattice random walkers chosen from an infinite set. It was assumed there that the residence time in one sojourn at the origin differed from the residence time of points elsewhere. In this paper we derive some properties of the corresponding first-passage time to the occupancy of the special site by k(>1) random walkers in one or two dimensions. Results of our study were obtained from an extensive set of simulations.

  16. 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.

  17. FriedmanRobertsonWalker 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 FriedmanRobertsonWalker (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.

  18. 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

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

    NASA Astrophysics Data System (ADS)

    Cook, Kerry H.; Vizy, Edward K.

    2015-10-01

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

  20. Novel method to form adaptive internal impedance profiles in walkers.

    PubMed

    Escudero Morland, Maximilano F; Althoefer, Kaspar; Nanayakkara, Thrishantha

    2015-08-01

    This paper proposes a novel approach to improve walking in prosthetics, orthotics and robotics without closed loop controllers. The approach requires impedance profiles to be formed in a walker and uses state feedback to update the profiles in real-time via a simple policy. This approach is open loop and inherently copes with the challenge of uncertain environment. In application it could be used either online for a walker to adjust its impedance profiles in real-time to compensate for environmental changes, or offline to learn suitable profiles for specific environments. So far we have conducted simulations and experiments to investigate the transient and steady state gaits obtained using two simple update policies to form damping profiles in a passive dynamic walker known as the rimless wheel (RW). The damping profiles are formed in the motor that moves the RW vertically along a rail, analogous to a knee joint, and the two update equations were designed to a) control the angular velocity profile and b) minimise peak collision forces. Simulation results show that the velocity update equation works within limits and can cope with varying ground conditions. Experiment results show the angular velocity average reaching the target as well as the peak force update equation reducing peak collision forces in real-time. PMID:26738092

  1. Uranium transport in the Walker River Basin, California and Nevada

    USGS Publications Warehouse

    Benson, L.V.; Leach, D.L.

    1979-01-01

    During the summer of 1976 waters from tributaries, rivers, springs and wells were sampled in the Walker River Basin. Snow and sediments from selected sites were also sampled. All samples were analyzed for uranium and other elements. The resulting data provide an understanding of the transport of uranium within a closed hydrologic basin as well as providing a basis for the design of geochemical reconnaissance studies for the Basin and Range Province of the Western United States. Spring and tributary data are useful in locating areas containing anomalous concentrations of uranium. However, agricultural practices obscure the presence of known uranium deposits and render impossible the detection of other known deposits. Uranium is extremely mobile in stream waters and does not appear to sorb or precipitate. Uranium has a long residence time (2500 years) in the open waters of Walker Lake; however, once it crosses the sediment-water interface, it is reduced to the U(IV) state and is lost from solution. Over the past two million years the amount of uranium transported to the terminal point of the Walker River system may have been on the order of 4 ?? 108 kg. This suggests that closed basin termini are sites for significant uranium accumulations and are, therefore, potential sites of uranium ore deposits. ?? 1979.

  2. Model and Statistical Analysis of the Motion of a Tired Random Walker in Continuum

    NASA Astrophysics Data System (ADS)

    Acharyya, Muktish

    The model of a tired random walker, whose jump-length decays exponentially in time, is proposed and the motion of such a tired random walker is studied systematically in one, two and three dimensional contin- uum. In all cases, the diffusive nature of walker, breaks down due to tiring which is quite obvious. In one dimension, the distribution of the displace- ment of a tired walker remains Gaussian (as observed in normal walker) with reduced width. In two and three dimensions, the probability distribution of displacement becomes nonmonotonic and unimodal. The most probable displacement and the deviation reduces as the tiring factor increases. The probability of return of a tired walker, decreases as the tiring factor increases in one and two dimensions. However, in three dimensions, it is found that the probability of return almost insensitive to the tiring factor. The prob- ability distributions of first return time of a tired random walker do not show the scale invariance as observed for a normal walker in continuum. The exponents, of such power law distributions of first return time, in all three dimensions are estimated for normal walker. The exit probability and the probability distribution of first passage time are found in all three dimensions. A few results are compared with available analytical calculations for normal walker.

  3. General mechanism for inchworm nanoscale track walkers: Analytical theory and realistic simulation

    NASA Astrophysics Data System (ADS)

    Li, Dan; Fan, Dagong; Wang, Zhisong

    2007-06-01

    Nanomotors capable of directed transportation along an unlimited linear track are being vigorously pursued both theoretically and experimentally. This study generalizes a previously proposed mechanism for nanoscale track walkers by explicitly treating key molecular details of the walker-track systems. An energy-diagram analysis identifies pathways of energy flow through the walker's movement cycle, and thereby enables us to develop an analytical theory for the track-walking mechanism. Realistic simulations of the walker's movement cycles are also conducted. The results show that the walker's directionality, run length, and speed depend critically on several key dimensional parameters of the walker-track systems. Most notably, the walker's performance as a function of the binding site interval of the track exhibits an oscillating pattern, which is accurately reproduced by the analytical theory. The wealth of nanocontrol mechanisms identified in the proposed track-walker systems not only provides a framework for optimizing performance of the walker, but also clarifies major requirements for future experimental implementation.

  4. 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.)

  5. 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.

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

    SciTech Connect

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

    1989-04-01

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

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sudhaker

    2015-05-01

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

  9. 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.

  10. Automatic Liver Segmentation Using the Random Walker Algorithm

    NASA Astrophysics Data System (ADS)

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

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

  11. Third annual Walker Branch watershed research symposium: Programs 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. 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 Department of Energy's local research site, Walker Branch Watershed, is a long-term ecosystem research project initiated on the Oak Ridge Reservation in 1967. Walker Branch provides a well-characterized site where many of these methods can be tested and applied.In addition, other large-scale experiments represented in this symposium include experiments on the effects of clearcutting and burning on forest structure and productivity associated with Coweeta Hydrologic Laboratory, and whole-tree ozone exposure chambers constructed by TVA and ORNL researchers

  12. Third annual Walker Branch watershed research symposium: Programs 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. 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 Department of Energy`s local research site, Walker Branch Watershed, is a long-term ecosystem research project initiated on the Oak Ridge Reservation in 1967. Walker Branch provides a well-characterized site where many of these methods can be tested and applied.In addition, other large-scale experiments represented in this symposium include experiments on the effects of clearcutting and burning on forest structure and productivity associated with Coweeta Hydrologic Laboratory, and whole-tree ozone exposure chambers constructed by TVA and ORNL researchers

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

    SciTech Connect

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

    1986-03-05

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

  14. A 'water walkers' exercise program for the elderly.

    PubMed Central

    Heyneman, C A; Premo, D E

    1992-01-01

    Recent studies have shown that older people, stereotyped as weak, frail, and inactive, demonstrate an equal capacity to reap the physical and psychological benefits of recreational exercise. A low cost aquatic exercise program is proposed that is geared towards those persons who, because of their physical limitations, are unable to participate in the more traditional walking or low-impact aerobics programs currently available for seniors. A water-based program would allow these people to gain all the advantages of land-based exercise with out stress or strain on arthritic joints. In addition, the use of water walkers (a buoyancy device which attaches easily around the waist) would allow total freedom of movement without fear of deep water. Those with various levels of disability could, therefore, participate at their own pace. Two programs, including transportation, would be provided twice a week for 8 weeks each. An individual 45-minute session would consist of a warm-up period with gentle stretching, a cardiovascular segment, a cool-down period, strength-training, and a final stretching time. All exercises would be conducted with participants wearing the water walkers, allowing total immersion to the shoulder. Free to move about the pool, they would be encouraged to interact socially with one another. The results of the program would be determined by measuring range of motion, cardiovascular endurance, and strength before and after each 8-week session. Participants' level of self confidence and life satisfaction will be estimated and any psychological improvement will be documented. PMID:1561306

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

    NASA Astrophysics Data System (ADS)

    Martnez-Garca, Ricardo; Lpez, Cristbal; 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.

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

    PubMed

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

    2015-08-01

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

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

    PubMed

    Hanley, Brian; Bissas, Athanassios

    2016-02-01

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

  18. Monocoque structure for the SKITTER three-legged walker

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

    Evapotranspiration is the ultimate path of outflow of nearly all water from the Lower Walker River basin. Walker Lake is the terminus of the topographically closed Walker River basin, and the lake level has been declining at an average rate of about 1.6 feet per year (ft/yr) since 1917. As a result of the declining lake level, dissolved-solids concentrations are increasingly threatening the fishery and ecosystem health of the lake. Uncertainties in the water budget components of the Lower Walker River basin led the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, to undertake an investigation to refine estimates of the water budget. Evapotranspiration from the Lower Walker River basin represents a major component of this water budget. The specific objectives of this report are to provide estimates of total and net evapotranspiration for water years 2005-07 for areas in the Lower Walker River basin in which annual evapotranspiration exceeds annual precipitation, and to summarize these results for areas of similar vegetation and soil characteristics, hydrographic subareas, and Walker Lake and Weber Reservoir. The three hydrographic subareas include the area along Walker River north of Walker Lake, the area of and adjacent to Walker Lake, and the area south of Walker Lake. Areas of annual evapotranspiration exceeding annual precipitation were identified and mapped in the field and were further delineated using remote-sensing analysis. These areas were classified into 10 evapotranspiration units. A network of 11 evapotranspiration stations was operated in natural and agricultural vegetation and on Walker Lake. Measured evapotranspiration rates ranged from 0.5 ft/yr at a sparsely vegetated desert shrub site to 5.0 ft/yr from Walker Lake. The greatest evapotranspiration rate on land was 4.1 ft/yr at an irrigated alfalfa field, and the greatest rate for natural vegetation was 3.9 ft/yr in a riparian community along Walker River. At an evapotranspiration station in a saltcedar grove, measurements indicated a possible decrease in evapotranspiration of about 50 percent due to defoliation of the saltcedar by the saltcedar leaf beetle. Total evapotranspiration from the evapotranspiration units identified in the Lower Walker River basin was about 231,000 acre-feet per year (acre-ft/yr). Of this amount, about 45,000 acre-ft/yr originated from direct precipitation, resulting in net evapotranspiration of about 186,000 acre-ft/yr. More than 80 percent of net evapotranspiration in the Lower Walker River basin was through evaporation from Walker Lake. Total evaporation from Walker Lake was about 161,000 acre-ft/yr and net evaporation was about 149,000 acre-ft/yr. Some previous estimates of evaporation from Walker Lake based on water-budget analysis actually represent total evaporation minus ground-water inflow to the lake. Historical evaporation rates determined on the basis of water budget analysis were less than the evaporation rate measured directly during this study. The difference could represent ground-water inflow to Walker Lake of 16,000 to 26,000 acre-ft/yr or could indicate that ground-water inflow to Walker Lake is decreasing over time as the lake perimeter recedes.

  20. 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…

  1. 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 identify new research needs and opportunities. We anticipate the integration of results and efforts with ongoing Earthscope projects, such as Sierra Nevada efforts of SNEP as well as the NSF Margins Rupturing of Continental Lithosphere (RCL) initiative in the Gulf of California by continuing the work onshore from the Gulf of California to the north into Nevada.

  2. 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 curvethe core-periphery profileand 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

  3. Towards Multi-fueled DNA walker on DNA trails

    NASA Astrophysics Data System (ADS)

    Nishikawa, Akio; Ohtake, Kazumasa; Tanaka, Fumiaki; Hagiya, Masami

    2008-10-01

    Basic idea and preliminary experimental results for photo-controllable DNA tiles are described. Although self-assembly of DNA cross tiles is an established technique, it only results in a static structure controlled by sequence design of sticky ends. For realizing dynamic control of DNA nanostructures, multi-fueled approach to self-assembly of DNA cross tiles is introduced. It is based on thermal-fuel, pH-fuel and photo-fuel. We already verified their basic behaviors in test tubes. In addition, we started to examine them for DNA walker on DNA trails made of DNA cross tiles. Especially, azobenzene intercalation groups for the sticky ends in DNA cross tiles are useful for photo-fuel, as they can control the assembly process with irradiation of UV/visible light. Preliminary results concerning the DNA cross tiles with azobenzene are also described briefly.

  4. Topology preservation and anatomical feasibility in random walker image registration.

    PubMed

    Andrews, Shawn; Tang, Lisa; Hamarneh, Ghassan

    2014-01-01

    The random walker image registration (RWIR) method is a powerful tool for aligning medical images that also provides useful uncertainty information. However, it is difficult to ensure topology preservation in RWIR, which is an important property in medical image registration as it is often necessary for the anatomical feasibility of an alignment. In this paper, we introduce a technique for determining spatially adaptive regularization weights for RWIR that ensure an anatomically feasible transformation. This technique only increases the run time of the RWIR algorithm by about 10%, and avoids over-smoothing by only increasing regularization in specific image regions. Our results show that our technique ensures topology preservation and improves registration accuracy. PMID:25333120

  5. Multiple phases and vicious walkers in a wedge

    NASA Astrophysics Data System (ADS)

    Delfino, Gesualdo; Squarcini, Alessio

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Grisa, Luca; Sorbo, Lorenzo

    2010-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  8. Effects of aging on identifying emotions conveyed by point-light walkers.

    PubMed

    Spencer, Justine M Y; Sekuler, Allison B; Bennett, Patrick J; Giese, Martin A; Pilz, Karin S

    2016-02-01

    The visual system is able to recognize human motion simply from point lights attached to the major joints of an actor. Moreover, it has been shown that younger adults are able to recognize emotions from such dynamic point-light displays. Previous research has suggested that the ability to perceive emotional stimuli changes with age. For example, it has been shown that older adults are impaired in recognizing emotional expressions from static faces. In addition, it has been shown that older adults have difficulties perceiving visual motion, which might be helpful to recognize emotions from point-light displays. In the current study, 4 experiments were completed in which older and younger adults were asked to identify 3 emotions (happy, sad, and angry) displayed by 4 types of point-light walkers: upright and inverted normal walkers, which contained both local motion and global form information; upright scrambled walkers, which contained only local motion information; and upright random-position walkers, which contained only global form information. Overall, emotion discrimination accuracy was lower in older participants compared with younger participants, specifically when identifying sad and angry point-light walkers. In addition, observers in both age groups were able to recognize emotions from all types of point-light walkers, suggesting that both older and younger adults are able to recognize emotions from point-light walkers on the basis of local motion or global form. (PsycINFO Database Record PMID:26765748

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

    USGS Publications Warehouse

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

    2006-01-01

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

  10. A review of the genus Monema Walker in China (Lepidoptera, Limacodidae)

    PubMed Central

    Pan, Zhaohui; Zhu, Chaodong; Wu, Chunsheng

    2013-01-01

    Abstract Four species and one subspecies of the genus Monema Walker, 1855 are recognized from China, in which Monema tanaognatha Wu & Pan sp. n. is described as new, Monema coralina Dudgeon, 1895 and Monema meyi Solovyev & Witt, 2009 are newly recorded for China. The female of Monema meyi is reported for the first time. Monema nigrans de Joannis, 1901 and Monema melli Hering, 1931 are synonymized with Monema flavescens Walker, 1855. Cnidocampa rubriceps Matsumura, 1931 is regarded here as a subspecies of Monema flavescens Walker, 1855. The photographs of moths and their genitalia are given. A key to the species of the genus is provided. PMID:23794916

  11. Influence of temperature on current-induced domain wall motion and its Walker breakdown

    NASA Astrophysics Data System (ADS)

    Fan, Lvchao; Hu, Jingguo; Su, Yuanchang; Zhu, Jinrong

    2016-03-01

    The current-driven domain wall propagation along a thin ferromagnetic strip with thermal field is studied by means of micromagnetic simulations. The results show that the velocity of domain wall is almost independent of temperature until Walker breakdown happened. However the thermal field can suppress Walker breakdown and makes domain wall move faster. Further analysis indicates that the thermal field tends to keep the out-of-plane magnetic moment of the domain wall stay in high value, which can promote domain wall motion and suppress the Walker breakdown by breaking the period of domain wall transformation.

  12. 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 users weight to ensure safe walking. PMID:26696700

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

    NASA Technical Reports Server (NTRS)

    1961-01-01

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

  14. 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 into the ancient lake bed, probably constraining flood flow to a much narrower region than in Mason Valley. In support of a reach scale morphodynamic model for the system, we estimated reach-average sediment exchange flux between eroding cut banks and new point bars. The estimates were derived from the overall rate of sinuosity increase for each subreach, rather than from simple lateral offset measurements which are sensitive to misalignment in the historic aerial photographs. Because bars are generally composed of coarser sediment than is typical for eroding cut banks, this exchange is probably associated with net storage of gravel in the floodplain. For several reaches in the dataset, lateral storage computed in this manner represents a significant fraction of bed material transport capacity.

  15. ISS Update: Astronaut Shannon Walker – 07.17.2012 - Duration: 19 minutes.

    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 ...

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

    NASA Video Gallery

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

  17. 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

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

    SciTech Connect

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

    2007-06-29

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

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

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

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

  20. 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.

  1. A jump persistent turning walker to model zebrafish locomotion.

    PubMed

    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

  2. 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.

  3. A superspace description of Friedmann-Robertson-Walker models

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sudhaker

    2015-09-01

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

  4. 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.

  5. 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

  6. Conformally Friedmann-Lemaître-Robertson-Walker cosmologies

    NASA Astrophysics Data System (ADS)

    Visser, Matt

    2015-07-01

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

  7. 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.

  8. 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.

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

    SciTech Connect

    Not Available

    1992-03-01

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

  10. Physical Activity, Weight Status, and Neighborhood Characteristics of Dog Walkers

    PubMed Central

    Coleman, Karen J.; Rosenberg, Dori E.; Conway, Terry L.; Sallis, James F.; Saelens, Brian E.; Frank, Lawrence D.; Cain, Kelli

    2008-01-01

    Objective This study examined how demographics, physical activity, weight status, and neighborhood characteristics varied among households with and without dogs. Method Participants aged 20 to 65 years (N = 2199, 52% male, 75% white, Mean age = 45) were recruited from 32 neighborhoods in the Seattle, WA and Baltimore, MD regions during 2002 – 2005. Dog ownership, dog walking, education, height, weight, and family income were self-reported. Minutes of moderate to vigorous physical activity (MVPA) were measured objectively by 7-day accelerometry. Results Dog walking was associated with a higher proportion of participants who met national recommendations for MVPA (53%) when compared to those who had but did not walk their dog (33%) and to non-dog owners (46%). There were significantly fewer obese dog walkers (17%) when compared to both owners who did not walk their dogs (28%) and non-owners (22%). Dog owners who walked their dogs were more likely to live in high-walkable neighborhoods when compared to dog owners who did not walk their dogs. Conclusion Dog walking may promote physical activity and contribute to weight control. Dog walking appears to be a mechanism by which residents of high-walkable neighborhoods obtain their physical activity. PMID:18572234

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Motionwhether it the ability to change shape, rotate or translateis 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 five-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 6? apart within an ?-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.

  12. Dynamics of unvisited sites in the presence of mutually repulsive random walkers

    NASA Astrophysics Data System (ADS)

    Das, Pratap Kumar; Dasgupta, Subinay; Sen, Parongama

    2007-06-01

    We have considered the persistence of unvisited sites of a lattice, i.e., the probability S(t) that a site remains unvisited till time t in the presence of mutually repulsive random walkers in one dimension. The dynamics of this system has direct correspondence to that of the domain walls in a certain system of Ising spins where the number of domain walls becomes fixed following a zero-temperature quench. Here we get the result that S(t) ~ exp(-?t?) where ? is close to 0.5 and ? a function of the density of the walkers ?. The fraction of persistent sites in the presence of independent walkers of density ?' is known to be S^\\prime (t) = \\exp\\big({-}2 \\sqrt{\\vphantom{A^A}\\smash{\\{\\frac{2{\\pi}} \\rho^\\prime t^{1/2}}}}\\big) . We show that a mapping of the interacting walkers' problem to the independent walkers' problem is possible with ?' = ?/(1 - ?) provided ?' and ? are small. We also discuss some other intricate results obtained in the interacting walkers' case.

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

    PubMed

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

    2015-07-29

    Dynamic DNA enzyme-based walkers complete their stepwise movements along the prescribed track through a series of reactions, including hybridization, enzymatic cleavage, and strand displacement; however, their overall translocation kinetics is not well understood. Here, we perform mechanistic studies to elucidate several key parameters that govern the kinetics and processivity of DNA enzyme-based walkers. These parameters include DNA enzyme core type and structure, upper and lower recognition arm lengths, and divalent metal cation species and concentration. A theoretical model is developed within the framework of single-molecule kinetics to describe overall translocation kinetics as well as each reaction step. A better understanding of kinetics and design parameters enables us to demonstrate a walker movement near 5 ?m at an average speed of ?1 nm s(-1). We also show that the translocation kinetics of DNA walkers can be effectively controlled by external light stimuli using photoisomerizable azobenzene moieties. A 2-fold increase in the cleavage reaction is observed when the hairpin stems of enzyme catalytic cores are open under UV irradiation. This study provides general design guidelines to construct highly processive, autonomous DNA walker systems and to regulate their translocation kinetics, which would facilitate the development of functional DNA walkers. PMID:26151085

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

    USGS Publications Warehouse

    Lopes, Thomas J.; Allander, Kip K.

    2009-01-01

    The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. Between 1882 and 2008, agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-ft. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes the hydrologic setting of the Walker River basin and a conceptual hydrologic model of the relations among streams, groundwater, and Walker Lake with emphasis on the lower Walker River basin from Wabuska to Hawthorne, Nevada. The Walker River basin is about 3,950 square miles and straddles the California-Nevada border. Most streamflow originates as snowmelt in the Sierra Nevada. Spring runoff from the Sierra Nevada typically reaches its peak during late May to early June with as much as 2,800 cubic feet per second in the Walker River near Wabuska. Typically, 3 to 4 consecutive years of below average streamflow are followed by 1 or 2 years of average or above average streamflow. Mountain ranges are comprised of consolidated rocks with low hydraulic conductivities, but consolidated rocks transmit water where fractured. Unconsolidated sediments include fluvial deposits along the active channel of the Walker River, valley floors, alluvial slopes, and a playa. Sand and gravel deposited by the Walker River likely are discontinuous strata throughout the valley floor. Thick clay strata likely were deposited in Pleistocene Lake Lahontan and are horizontally continuous, except where strata have been eroded by the Walker River. At Walker Lake, sediments mostly are clay interbedded with alluvial slope, fluvial, and deltaic deposits along the lake margins. Coarse sediments form a multilayered, confined-aquifer system that could extend several miles from the shoreline. Depth to bedrock in the lower Walker River basin ranges from about 900 to 2,000 feet. The average hydraulic conductivity of the alluvial aquifer in the lower Walker River basin is 10-30 feet per day, except where comprised of fluvial sediments. Fluvial sediments along the Walker River have an average hydraulic conductivity of 70 feet per day. Subsurface flow was estimated to be 2,700 acre-feet per year through Double Spring. Subsurface discharge to Walker Lake was estimated to be 4,400 acre-feet per year from the south and 10,400 acre-feet per year from the north. Groundwater levels and groundwater storage have declined steadily in most of Smith and Mason Valleys since 1960. Groundwater levels around Schurz, Nevada, have changed little during the past 50 years. In the Whisky Flat area south of Hawthorne, Nevada, agricultural and municipal pumpage has lowered groundwater levels since 1956. The water-level decline in Walker Lake since 1882 has caused the surrounding alluvial aquifer to drain and groundwater levels to decline. The Wabuska streamflow-gaging station in northern Mason Valley demarcates the upper and lower Walker River basin. The hydrology of the lower Walker River basin is considerably different than the upper basin. The upper basin consists of valleys separated by consolidated-rock mountains. The alluvial aquifer in each valley thins or pinches out at the downstream end, forcing most groundwater to discharge along the river near where the river is gaged. The lower Walker River basin is one surface-water/groundwater system of losing and gaining reaches from Wabuska to Walker Lake, which makes determining stream losses and the direction and amount of subsurface flow difficult. Isotopic data indicate surface water and groundwater in the lower Walker River basin are from two sources of precipitation that have evaporated. The Walker River, groundwater along the Wassuk Range, and Walker Lake plot along one evaporation line. Groundwater along th

  15. Glucagon degradation by a product of the Walker 256 carcinosarcoma

    SciTech Connect

    Zepp, E.A.

    1986-03-05

    Male Sprague-Dawley rats (125-150g) were implanted (im.) with the Walker 256 carcinosarcoma. After both 7 and 10 days, plasma levels of glucagon in tumor-bearing rats were approximately half the level seen in control rats (P < 0.01) even though fasting plasma glucose levels were slightly (but not significantly) less in the tumor-bearing rats. To determine if the tumor degrades the hormone, tumor cells were incubated at room temperature with /sup 125/I-glucagon (0.075 ..mu..Ci, 2200 Ci/mmol) in 20mM TRIS-HCl buffer (pH 7.4) with 2.5% bovine serum albumin (total volume of 750 ..mu..l) for 45 min. After incubation with tumor cells, only about 25% of the total radiolabel was TCA-precipitable vs 97% in the control (minus tumor cells) incubations. It also appears that the tumor cells may release a substance which degrades hormone. If tumor cells are preincubated for 60 min at 37/sup 0/ then removed from the medium, the incubation medium contains a factor which degrades subsequently added /sup 125/I-glucagon (57% TCA-precipitable vs 98% in control incubations). That this factor is a protease is suggested by the results of another experiment in which aprotinin (a protease inhibitor, 1 mg/ml), when added along with the labeled glucagon, virtually eliminated degradation by a factor released from the tumor cells (79% TCA-precipitable in the absence of aprotinin vs 94% in its presence and 98% in controls).

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

    NASA Astrophysics Data System (ADS)

    Pier, Jeffrey R.; Mason, Brian

    2005-12-01

    Dick Walker, 67, died 30 March 2005 in Flagstaff, AZ, following a long illness. He was born on 9 March 1938 in Hampton, Iowa and grew up in Waterloo, Iowa. As a child, Dick was fascinated with astronomy and built his own telescope. He saved his pennies and bought and read every book on the subject he could find. He also raised pigeons, naming four of them Hertzsprung, Hoyle, Gamow, and Kron. In 1957, the year Sputnik was launched, Dick began his college studies at the University of Northern Iowa in Cedar Falls. In 1959, he transferred to the State University of Iowa (subsequently renamed the University of Iowa) in Iowa City, where he earned a BA degree in astronomy and physics in 1963. He joined the staff of the U.S. Naval Observatory in Washington, DC, where he worked in the Time Service Division for a year before his assignment to the Astrometry and Astrophysics Division. Dick relocated to Flagstaff, AZ, in 1966 to continue his Naval Observatory service at the Flagstaff Station. His retirement in May 1999, ended a thirty-six-year career with USNO. Dick was first and foremost an observational astronomer. From the mid 1960s through the late 1970s, much of Dick's time was devoted to the measurement of binary stars, observing with the 12-inch and 26-inch refractors in Washington and later the 40-inch and 61-inch reflectors in Flagstaff. He also made many trips to Lick Observatory to work with the 36-inch Clark Refractor there. During this time he consulted with Charles Worley, who was observing on the 26-inch, to make sure time was well-spent examining doubles that could not be observed in Washington. This period of observing overlapped with the early years of speckle interferometry, and Dick's observations, made with the largest telescope used for micrometry at the time, were very important for ascertaining the veracity of this new technique. He was a studious and very careful observer of doubles and made over 8,000 measures, resulting in almost 3,000 mean positions. While measuring known systems for orbital analysis, he discovered 22 pairs (mostly additional components to these systems) and moving pairs, and his highlighting the rapid motion of these systems resulted in them being placed on many programs and led to the more definitive orbits of today. As a staff member of the Flagstaff Station, Dick was, for over 30 years, one of the principal observers on the 61-inch parallax program. He also ventured into other areas of astronomy, including planetary systems. He is credited with discovering the moon of Saturn, Epimetheus, in December 1966, with the USNO Flagstaff Station 61-inch Kaj Strand Astrometric Reflector. He also obtained photographic plates to determine accurate positions of the outer planets for the Voyager 2 approaches to Uranus in 1986 and Neptune in 1989. It is interesting to note that Dick's career in observational astronomy spanned three different eras of astronomical instrumentation and technique. He began his career doing eyeball astronomy, using a filar micrometer to measure double star separations. Photographic astronomy then became dominant and he took many thousands of plates. During the last ten years of his career, electronic cameras, primarily CCDs, replaced photographic plates. He readily adapted to the changing technologies. A man of many interests, Dick was fascinated by the history of astronomy, especially archeoastronomy, as well as Egyptology. He taught himself the language of hieroglyphics. In 1977, having accumulated several weeks of vacation time, he set off on a trek to walk the Nile for 500 miles from Aswan to Cairo. One night, in the town Asyut along the Nile, he was brought into the police station. The local inhabitants found it hard to credit his story that he was simply on a walk and questioned him as a possible Israeli spy. Following his retirement from the Naval Observatory, Dick consulted in a couple of construction projects. He designed the analemma and the skywalk star fields for the Koch Center for Science, Math, and Technology at Deerfield Academy in Massachusetts. He also consulted with James Turrell, providing astronomical position information for the design of the Roden Crater Project outside of Flagstaff. While he will be remembered for his significant scientific contributions to the field of astronomy, those who knew Dick, both scientists and non-scientists alike, will probably remember him best for his humility, his humanity, and his loyal and abiding friendship. He was a man with a terrific sense of humor and an infectious laugh. It was always an honor and pleasure to be in his company. Richard L. Walker, Jr. is survived by his wife, Patricia, two daughters from his first marriage: Brenda Walker of Las Vegas, NV, and Pamela Hepburn of Holland, OH, as well as four children from Patricia's first marriage: Doug Browning of Lake Havasu City, AZ, Michael Browning of Kingman, AZ, Kim Bructo of Orient, OH, and Jennifer Brown of Lake Havasu City, AZ. He is also survived by ten grandchildren and three great-grandchildren. He was preceded in death by his father Richard, mother Mary, and daughter, Paula Jean Elizabeth Stone.

  17. The Fire-Walkers High: Affect and Physiological Responses in an Extreme Collective Ritual

    PubMed Central

    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

  18. Hydrologic data for the Walker River Basin, Nevada and California, water years 201014

    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.

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

    PubMed

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

    2014-01-01

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

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

    SciTech Connect

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

    1993-04-01

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

  1. 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, Fbio 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 25mg/Kg) was administered orally for 12days, 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

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

    NASA Technical Reports Server (NTRS)

    1952-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Bakke, K.; Furtado, C.; Carvalho, A. M. De M.

    2015-04-01

    The Wigner rotation angle for a particle in a circular motion in the Schwarzschild spacetime is obtained via the Fermi-Walker transport of spinors. Then, by applying the Wentzel, Kramers, Brillouin (WKB) approximation, a possible application of the Fermi-Walker transport of spinors in relativistic Einstein-Podolsky-Rosen (EPR) correlations is discussed, where it is shown that the spins of the correlated particle undergo a precession in an analogous way to that obtained by Terashima and Ueda [H. Terashima and M. Ueda, Phys. Rev. A 69, 032113 (2004)] via the application of successive infinitesimal Lorentz transformations. Moreover, from the WKB approach, it is also shown that the degree of violation of the Bell inequality depends on the Wigner rotation angle obtained via the Fermi-Walker transport. Finally, the relativistic effects from the geometry of the spacetime and the accelerated motion of the correlated particles is discussed in the nonrelativistic limit.

  4. 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.

  5. VizieR Online Data Catalog: BV Color-Magnitude Diagram for NGC 1851 (Walker 1992)

    NASA Astrophysics Data System (ADS)

    Walker, A. R.

    1993-07-01

    BV photometry is provided for 1,234 stars in the magnitude range 13-18 in an annulus between 5 and 20 arc seconds from the center of NGC 1851 and for 1,247 stars in the magnitude range 18-23 at a distance of more than 240 arc seconds from the center. For stars in the magnitude range 16-21, the errors in B-V increase with magnitude from 0.005 mag. to 0.022 mag. See the document file (walker.txt or walker.tex) by Nancy G. Roman for more details. (1 data file).

  6. 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.

  7. 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)....

  8. 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...

  9. 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

  10. [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

  11. 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...

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

    ERIC Educational Resources Information Center

    Reeves, John E.; And Others

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

  13. 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…

  14. STS-30 Commander David M. Walker during preflight press conference at JSC

    NASA Technical Reports Server (NTRS)

    1989-01-01

    During preflight press conference, STS-30 Commander David M. Walker monitors a question from a news media representative. The event was held in the JSC Auditorium and Public Affairs Facility Bldg 2 briefing room. STS-30 mission will fly onboard Atlantis, Orbiter Vehicle (OV) 104, and is scheduled for an April 28 liftoff.

  15. 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

  16. 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…

  17. 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

  18. 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...

  19. 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.

  20. 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

  1. 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)

  2. 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.

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

    SciTech Connect

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

    2005-10-01

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

  4. 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)

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

    SciTech Connect

    Van Siclen, Clinton D

    2002-01-01

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

  6. 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...

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

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

    Code of Federal Regulations, 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...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

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

    Code of Federal Regulations, 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...

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

    ERIC Educational Resources Information Center

    Matunda, Robert Stephen Mokaya

    2009-01-01

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

  12. 78 FR 37706 - Safety Standards for Infant Walkers and Infant Swings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ... for Infant Walkers, with 22 modifications to make the standard more stringent. 75 FR 35266. ASTM..., with two modifications to make the standard more stringent. 77 FR 66703. ASTM notified CPSC that the... adverse comment. See 60 FR 43108 (August 18, 1995). Thus, the Commission is publishing this rule as...

  13. 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.

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

    ERIC Educational Resources Information Center

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

    2004-01-01

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

  15. Guide to the Papers in the John Hunter Walker Collection, 1911-1953.

    ERIC Educational Resources Information Center

    Carlson, Douglas W.; And Others

    This guide to the papers of John Hunter Walker (1872-1955) which are housed in the Illinois Historical Survey Library includes a biographical sketch of this prominent Illinois labor leader and key figure in both the Illinois State Federation of Labor and the United Mine Workers of America; an organizational statement explaining the acquisition of

  16. Variability in the Length and Frequency of Steps of Sighted and Visually Impaired Walkers

    ERIC Educational Resources Information Center

    Mason, Sarah J.; Legge, Gordon E.; Kallie, Christopher S.

    2005-01-01

    The variability of the length and frequency of steps was measured in sighted and visually impaired walkers at three different paces. The variability was low, especially at the preferred pace, and similar for both groups. A model incorporating step counts and step frequency provides good estimates of the distance traveled. Applications to

  17. 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

  18. 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…

  19. 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…

  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 occurs in the westernmost fault systems near the Sierra Nevada crest, Lake Tahoe, and Carson Range faults where horizontal extension rates normal to the fault are as high as 1.8 mm/yr. Normal slip rates elsewhere in the Walker Lane are similar in rate to the rest of the Basin and Range. The Mohawk Valley fault slips faster than any fault in the entire system, about 2.8 mm/yr of dextral slip. These results suggest that contemporary extension on normal faults nearest the Sierra Nevada Range Front may drive the seismic hazard for the nearby Reno/Tahoe metropolitan areas.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    Alastair Graham Walker Cameron, one of the most creative and influential astrophysicists of his generation, passed away on 3 October 2005, at the age of 80, at his home in Tucson. Subsequent to his retirement from Harvard University, where he had been a member of the faculty from 1973 through 1999, Cameron remained active as a Senior Research Scientist at the Lunar and Planetary Laboratory of the University of Arizona. Cameron had a distinguished career during which he made outstanding contributions both in scientific research and in public service to science. Notable among the latter are the years he spent as Chairman of the Space Science Board of the National Academy of Sciences from 1976 to 1982. He was a member of the National Academy of Sciences and the recipient of a number of awards for his diverse contributions to the sciences, including the J. Lawrence Smith Medal of the National Academy of Sciences in 1988, the Leonard Medal of the American Meteoritical Society in 1994, the Henry Norris Russell Lectureship of the American Astronomical Society in 1997, and the Hans A. Bethe prize of the Division of Nuclear Physics of the American Physical Society for 2006, for outstanding work in nuclear physics and astrophysics. He was enormously active in the organization of conferences and workshops and in an editorial capacity, for a number of journals in astronomy, astrophysics, and space physics. Over the course of his career, he made seminal contributions to such diverse areas of astronomical and astrophysical research as nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, meteoritics, stellar evolution, neutron stars, the origin of the Solar System, the physics of planets and planetary atmospheres, and the origin of the Moon. Born on 21 June 1925 in Winnipeg, Manitoba, Cameron received his undergraduate degree from the University of Manitoba and his doctorate in nuclear physics from the University of Saskatchewan in 1952. He taught for two years at Iowa State and then spent seven years as a Senior Research Officer at Chalk River. It was from this period that his important early contributions to nuclear astrophysics emerged. His research addressed a broad range of problems concerning the origin of the elements, culminating in the publication in 1957 of a discussion of stellar evolution and nucleosynthesis which, together with the paper by E.M. Burbidge, G.F. Burbidge, W.A. Fowler, and F. Hoyle, substantially defined the field of nucleosynthesis as we understand it today. Cameron joined the staff of the NASA Institute for Space Studies in New York and served as a Senior Scientist from 1961 to 1966, then continued on to the Belfer Graduate School of Science of Yeshiva University in New York, prior to moving to Harvard. Working with an increasing number of graduate students and postdocs, Cameron continued his studies in nuclear physics, concentrating on building systematics of nuclear mass formulae, nuclear level densities, thermonuclear reaction rates, and weak interaction rates. These nuclear systematics, coupled to early calculations of supernova explosions, enabled the first detailed numerical investigations of explosive nucleosynthesis from which the identification of 56Ni as the dominant product emerged. During these years, Cameron's research activities and interests expanded considerably to encompass broad areas of space physics, including specifically the origin of the Solar System. Notable here is the significant role he played in the early formulation and development of the impact theory for the origin of the Moon. This theory posits - and early numerical simulations by Cameron and his collaborators confirmed - that the collision of a large, Mars sized object with the Earth early in its history yields debris from which the Moon can coalesce, and can account for both an iron-depleted Moon and the masses and angular momentum of the Earth-Moon system. Cameron was an extremely imaginative and productive scientist whose contributions profoundly influenced many areas of research in what he liked to refer to as cosmogony. The proceedings of the symposium which celebrated his sixtieth birthday were indeed published, at his request, under the title "Cosmogonical Processes." He was also a strong early advocate of distributed computing, as anyone who visited his research office at Harvard will well remember. To those who worked closely with him, as students, postdocs, or colleagues, he will be remembered for his encouragement of young scientists, his enthusiastic acceptance of new ideas, and his pure enjoyment of his science.

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

    PubMed

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

    2009-12-01

    The gait outcome measures used in clinical trials of paraplegic locomotor training determine the effectiveness of improved walking function assisted by the functional electrical stimulation (FES) system. Focused on kinematic, kinetic or physiological changes of paraplegic patients, traditional methods cannot quantify the walking stability or identify the unstable factors of gait in real time. Up until now, the published studies on dynamic gait stability for the effective use of FES have been limited. In this paper, the walker tipping index (WTI) was used to analyze and process gait stability in FES-assisted paraplegic walking. The main instrument was a specialized walker dynamometer system based on a multi-channel strain-gauge bridge network fixed on the frame of the walker. This system collected force information for the handle reaction vector between the patient's upper extremities and the walker during the walking process; the information was then converted into walker tipping index data, which is an evaluation indicator of the patient's walking stability. To demonstrate the potential usefulness of WTI in gait analysis, a preliminary clinical trial was conducted with seven paraplegic patients who were undergoing FES-assisted walking training and seven normal control subjects. The gait stability levels were quantified for these patients under different stimulation patterns and controls under normal walking with knee-immobilization through WTI analysis. The results showed that the walking stability in the FES-assisted paraplegic group was worse than that in the control subject group, with the primary concern being in the anterior-posterior plane. This new technique is practical for distinguishing useful gait information from the viewpoint of stability, and may be further applied in FES-assisted paraplegic walking rehabilitation. PMID:19918110

  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, 2545km 1510 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. Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers.

    PubMed

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

    2006-12-01

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

  5. Late Quaternary seismic stratigraphic framework and paleolimnology of Walker Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Friday, M.; Scholz, C. A.; Junium, C. K.

    2014-12-01

    Lake deposits can be used to assess past hydrological and atmospheric conditions and aid in understanding regional climate of the western Basin and Range. Walker Lake, Nevada has a maximum water depth of ~35 m and is situated in a half-graben basin that formed during late Cenozoic transtension, in the Walker Lane tectonic belt. Small-scale climatic variations are preserved in the sediments of this hydrologically closed lake basin. Ten Kullenberg sediment cores (~2 to ~10 m in length), and ~300 km of CHIRP seismic reflection data were collected in Walker Lake to assess late-Quaternary stratigraphic framework and paleoclimate history. Core 4A is one of the longest cores acquired (9.19 m) and contains the oldest recovered sediments. Analyses of total inorganic carbon, total organic carbon, carbon and nitrogen abundances, and carbon stable isotopes from core 4A yield a valuable multi-proxy paleoclimate record. This record documents changes in effective moisture in the eastern Sierra Nevada and western Basin and Range. Sediments range from laminated to massive mud with three tephra deposits 0.5 - 4 cm thick. Total percentage of calcium carbonate, ranging from 3 to 35%, shows oscillations we interpret to be millennial forcings. The average C/N ratio of core 4A is 7.71 (2.5 - 11.3 range), and the stable carbon isotope measurements range from -21.0 to -25.3‰, and average -23.8‰. At ~3.7 m depth a basin-wide angular unconformity is observed in the seismic data and is also reflected in the geochemical data. An estimated age of this surface, 2000-2500 ka, is consistent with previous interpretations of partial diversion of the Walker River into the Carson sink. A δ13Corganic excursion, -25 to -20.8‰, occurs at the depth of the unconformity. We interpret this to be a result of enhanced deposition of aquatic organic matter during the Walker Lake drawdown. From 3.7 to 7.5 m depth, the carbon and nitrogen abundances and isotopes are surprisingly consistent down core and may be the result of protracted stability. Below 7.5 m depth the carbon and nitrogen abundances decrease, as do %CaCO3 and δ13Corganic values. These signatures may reflect past connectivity between Walker Lake and other Lahontan sub-basins. AMS radiocarbon analyses are underway, which will help constrain the paleolimnologic history of the basin.

  6. Decoherence induced by a chaotic enviroment: A quantum walker with a complex coin

    SciTech Connect

    Ermann, Leonardo; Paz, Juan Pablo; Saraceno, Marcos

    2006-01-15

    We study the differences between the processes of decoherence induced by chaotic and regular environments. For this we analyze a family of simple models that contain both regular and chaotic environments. In all cases the system of interest is a ''quantum walker,'' i.e., a quantum particle that can move on a lattice with a finite number of sites. The walker interacts with an environment which has a D-dimensional Hilbert space. The results we obtain suggest that regular and chaotic environments are not distinguishable from each other in a (short) time scale t*, which scales with the dimensionality of the environment as t*{proportional_to}log{sub 2}(D). However, chaotic environments continue to be effective over exponentially longer time scales while regular environments tend to reach saturation much sooner. We present both numerical and analytical results supporting this conclusion. The family of chaotic evolutions we consider includes the so-called quantum multibaker map as a particular case.

  7. Fast random walker with priors using precomputation for interactive medical image segmentation.

    PubMed

    Andrews, Shawn; Hamarneh, Ghassan; Saad, Ahmed

    2010-01-01

    Updating segmentation results in real-time based on repeated user input is a reliable way to guarantee accuracy, paramount in medical imaging applications, while making efficient use of an expert's time. The random walker algorithm with priors is a robust method able to find a globally optimal probabilistic segmentation with an intuitive method for user input. However, like many other segmentation algorithms, it can be too slow for real-time user interaction. We propose a speedup to this popular algorithm based on offline precomputation, taking advantage of the time images are stored on servers prior to an analysis session. Our results demonstrate the benefits of our approach. For example, the segmentations found by the original random walker and by our new precomputation method for a given 3D image have a Dice's similarity coefficient of 0.975, yet our method runs in 1/25th of the time. PMID:20879377

  8. Magnetohydrodynamic perturbations of Robertson-Walker universes and of anisotropic Bianchi type-I universes

    NASA Technical Reports Server (NTRS)

    Fennelly, A. J.; Evans, C. R.

    1980-01-01

    Magnetohydrodynamic (MHD) perturbations in flat Robertson-Walker universes were analyzed, emphasizing their effects on galaxy formation. The Newtonian approximation is used. There is no increase in the growth rates beyond those of the usual perturbed Robertson-Walker models; the MHD modes extract as much energy as they contribute. Some global properties of fully MHD Bianchi I relativistic models are analyzed including vorticity, fluid accelerations, and dissipative effects. The time dependence of perturbations of a fully MHD diagonal Bianchi I cosmology is studied, with an enhanced growth rate of the density contrast of t found which is still not exponential Jeans-type growth. This indicates that a more detailed analysis is needed if a solution to the galaxy formation problem in MHD cosmologies is to be found.

  9. Pore geometry: Control on reservoir properties, Walker Creek Field, Columbia and Lafayette Counties, Arkansas

    SciTech Connect

    Bliefnick, D.M.; Kaldi, J.G.

    1996-07-01

    Walker Creek field in southern Arkansas produces hydrocarbons from oolitic packstones and grainstones of the Jurassic Smackover Formation. The relationships between pore geometry and reservoir quality in these rocks were evaluated using petrographic methods and mercury injection capillary pressure analyses. Results indicate that reservoir quality is controlled by pore geometry, which, in turn, is determined by depositional and diagenetic processes. Reservoir rocks at Walker Creek were deposited as prograding grainstone shoals in a shallow-water, high-energy environment. Diagenetic processes, including early marine cementation, compaction, and deeper burial pressure solution and calcite cementation, modified the original pore system. Primary interparticle porosity is the dominant effective pore type and is most important in terms of reservoir performance. Secondary microporosity is also abundant, comprising a significant percentage of total porosity (locally up to 100%), but is generally ineffective.

  10. 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.

  11. Schizophrenia-Like Psychosis and Dandy-Walker Variant Comorbidity: Case Report

    PubMed Central

    Kıvılcım, Yiğit; İzci, Filiz; Semiz, Umit Basar

    2014-01-01

    Dandy-Walker variant is a developmental malformation consisting of cerebellar hypoplasia and cystic dilatation of the fourth ventricle. Previous research has proposed a possible role for the cerebellum in cognition and in schizophrenia. In this paper we report a schizophrenia-like psychotic disorder in a 30 year-old woman with Dandy-Walker variant. The patient was treated with risperidone 6 mg/day, biperiden 4 mg/day and risperidone depot 50 mg injections fortnightly, and most of the symptoms were ameliorated within 2 months. The similar cognitive profile to populations with cerebellar pathology and rarity of the condition strongly suggests that there may be direct relationship between cerebellar pathology and appearence of psychotic symptoms. PMID:24605131

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

    PubMed

    da Silva, Airton R; Sup, Frank

    2013-06-01

    This paper presents the preliminary design results and control strategy of a two-wheeled inverted pendulum (TWIP) robotic walker for assisting mobility-impaired users with balance and stability. A conceptual model of the vehicle is developed and used to illustrate the purpose of this study. Motor dynamics is considered and the linearized equations of motion for the system are derived using Newtonian mechanics. In order to eliminate the effects of loop interaction and impose the desired dynamics on the system, a decoupling control scheme was implemented. Upright stabilization of the robotic walker is achieved using linear quadratic regulator (LQR) control. Improved disturbance rejection is achieved through the implementation of a pitch controller. Simulation results demonstrate that a robustly tuned pitch controller can mitigate effect of disturbance on the linear displacement of the vehicle by as much as 74%. PMID:24187265

  13. Magnetic Resonance Imaging of An Adult with the Dandy-Walker Syndrome

    PubMed Central

    Stovall, Joyce M.; Venkatesh, Ramachandran

    1988-01-01

    A 30-year-old retired veteran was asymptomatic for two decades; he had carried out normal everyday living activities and was self-supporting. It was not until he was struck by an automobile, which resulted in head trauma, that the Dandy-Walker syndrome was incidentally discovered by computed tomography. Most patients with the Dandy-Walker syndrome or malformation are infants and seldom live into adulthood. Therefore, this patient is one of the very few patients with this malformation who remained in a state of cerebrospinal fluid compensation and lived to adulthood. The head trauma he received in the accident is believed to have activated neurological deficits, visual impairment, and diplopia. Although magnetic resonance imaging revealed severe hydrocephalus and lobar holoprosencephaly, the patient had no symptoms of increased intracranial pressure and no craniofacial deformities except for macrocephaly, and was capable of performing everyday living activities adequately. ImagesFigure 1Figure 2Figure 3 PMID:3249328

  14. 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.

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

    ERIC Educational Resources Information Center

    Huber, Germaine W.

    2009-01-01

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

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

    SciTech Connect

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

    2014-03-01

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

  18. 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.

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

    PubMed Central

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Mashiyama, Hiroyuki; Mashiyama, Kazuko

    1999-04-01

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

  1. The Friedmann-Lematre-Robertson-Walker Big Bang Singularities are Well Behaved

    NASA Astrophysics Data System (ADS)

    Stoica, Ovidiu Cristinel

    2015-04-01

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

  2. 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.

  3. 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.

  4. 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

  5. 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 26C 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.

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

    PubMed

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

    2004-01-01

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

  7. 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%: ?0.96.6] vs. 8.2% [CI95%: 4.711.8]; p=0.02). The odds of being a slow walker were 6.4 (CI95%: 1.724.9, p=0.007) if there was a high burden of white matter hyperintensity, however, this risk increased to 14.5 (CI95%: 2.391.1, 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

  8. 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.

  9. 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.

  10. 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

  11. 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 Nio/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 Nio (La Nia) 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 Nio 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.

  12. 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.

  13. A Novel Function for the Conserved Glutamate Residue in the Walker B Motif of Replication Factor C

    PubMed Central

    Chiraniya, Ankita; Finkelstein, Jeff; ODonnell, Mike; Bloom, Linda B.

    2013-01-01

    In all domains of life, sliding clamps tether DNA polymerases to DNA to increase the processivity of synthesis. Clamp loaders load clamps onto DNA in a multi-step process that requires ATP binding and hydrolysis. Like other AAA+ proteins, clamp loaders contain conserved Walker A and Walker B sequence motifs, which participate in ATP binding and hydrolysis, respectively. Mutation of the glutamate residue in Walker B motifs (or DExx-boxes) in AAA+ proteins typically reduces ATP hydrolysis by as much as a couple orders of magnitude, but has no effect on ATP binding. Here, the Walker B Glu in each of the four active ATP sites of the eukaryotic clamp loader, RFC, was mutated to Gln and Ala separately, and ATP binding- and hydrolysis-dependent activities of the quadruple mutant clamp loaders were characterized. Fluorescence-based assays were used to measure individual reaction steps required for clamp loading including clamp binding, clamp opening, DNA binding and ATP hydrolysis. Our results show that the Walker B mutations affect ATP-binding-dependent interactions of RFC with the clamp and DNA in addition to reducing ligand-dependent ATP hydrolysis activity. Here, we show that the Walker B glutamate is required for ATP-dependent ligand binding activity, a previously unknown function for this conserved Glu residue in RFC. PMID:23946885

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    PubMed Central

    Weiss, H. B.

    1996-01-01

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

  17. Siting of Large Volcanic Centers at Releasing Fault Stepovers, Walker Lane Rift

    NASA Astrophysics Data System (ADS)

    Busby, C.

    2011-12-01

    The transtensional eastern boundary of the Sierran microplate (Walker Lane rift) represents the northernmost extension of the Gulf of California rift, and it forms an onland analog in several ways. It formed at the same time (about 12 Ma), by a similar mechanism: transtension within the thermally- and structurally-weakened axis of a subduction-related arc. The two segments show similar structural trends: NE oblique slip normal faults (Walker Lane) or seafloor spreading centers (Gulf of California), connected by long NNW strike slip faults. However, the process of continental rupture has not yet been completed in the Walker Lane, so the structural controls on transtensional rift volcanism can be directly observed on land. The Walker Lane segment also differs from the Gulf of California segment by showing a northward time-transgressive transition from arc rift magmatism to continental rift magmatism, following the northward migration of the Mendocino triple junction (MTJ). The effect of MTJ migration has been previously recognized in arc to rift geochemical transitions, but not in the timing of development of large arc volcanic fields. For the past ~11-12 Ma, the biggest arc rift and continental rift volcanic centers or fields have been sited on major releasing fault stepovers on the trailing edge of the Sierran microplate. Additionally, major transtensional arc rift centers or fields appear to have progressively migrated northward with time, in advance of the TMJ, although gaps exist in detailed map and age data. These large transtensional arc volcanic fields/centers are, from south to north (oldest to youngest): (1) A ~11 - 9 Ma arc volcanic field that lies along the Sierran crest and rangefront in the Sonora Pass - Bridgeport area of the central Sierra Nevada. Its transtensional structural setting and its size (~ 50 X 50 km) had not been appreciated prior to my field efforts with students, although a modest-sized caldera in this volcanic field had long been recognized ("Little Walker caldera" of Priest, 1979). At this center, "flood andesites" were erupted from 6-8 km long fault-controlled fissures and ponded in grabens, to thicknesses of 400 m, with single flows up to 25 km3 in volume. Total volume is difficult to estimate due to Pleistocene glacial erosion, but it is >200 km3. (2) The Ebbetts Pass center, which formed at ~5-4 Ma (dating in progress with Paul Renne, BGC). This large center had not been recognized prior to our mapping; it appears to be a complex central volcano with a large footprint (>16 km diameter, glacially eroded). Its original volume may be better estimated after its collapse deposits are mapped and dated, because it appears to have repeatedly collapsed into range-front half grabens. (3) The active Lassen arc volcanic center, which formed at <3.5 Ma in a transtensional environment "favorable to the development of major volcanic centers" (Muffler et al., 2008, EOS 8-53). The active Long Valley rift volcanic field south of the MTJ also formed in a releasing bend in the Walker Lane transtensional rift (since ~4.5 Ma); the structure of this field (Jayko and Bursik, in press) is remarkably similar to that of the ~11-9 Ma arc rift volcanic field at Sonora Pass (Busby, in press; both in Tectonics of Sedimentary Basins, Wiley Blackwell, 2012).

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

    PubMed

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

    2015-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. 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)

  1. Terrestrial and Aquatic Controls on Watershed Biogeochemistry Respond Differently to Climate Change: Walker Branch, TN

    NASA Astrophysics Data System (ADS)

    Lutz, B. D.; Bernhardt, E. S.

    2012-12-01

    Most long-term watershed monitoring sites focus on catchments with shallow soils, consolidated bedrock, and small groundwater volumes such that hydrologic budgets can be accurately quantified. These characteristics make it difficult to disentangle the terrestrial and aquatic processes that govern biogeochemical cycles by limiting the pathways that water can be routed through watersheds. We analyzed 20 years of weekly streamwater chemistry data for the Walker Branch watershed (TN, USA), a site with exceptionally deep soils, complex soil flowpath structure, and large groundwater volumes that feed perennial springs. We show that long-term trends in climate patterns have altered catchment flowpath structure, such that vegetation and surface soils are becoming increasingly hydrologically isolated from the stream channel and that deep groundwater comprises a greater proportion of streamflow. Groundwater is chemically distinct from water that passes through shallow soils and, thus, changing flowpath contributions have resulted in long-term trends in streamwater solute concentrations and fluxes. Groundwater also exhibits little variation in solute concentrations across seasons and years, providing an ideal backdrop against which aquatic processes can be assessed. Aquatic processes in Walker Branch can have important effects on streamwater biogeochemistry during baseflow, but are sensitive to hydrologic disturbance and storm frequency. In addition to the long-term restructuring of soil flowpaths affecting terrestrial controls on biogeochemical patterns, changes in the frequency and intensity of storms have had distinct effects on aquatic controls governing solute concentrations and fluxes. The characteristics of Walker Branch that are generally considered undesirable for constructing water budgets and which set it apart from most other long-term watershed monitoring sitesdeep soils with complex flowpath structuring and large groundwater volumesallow us to disentangle the effects of upland vs. in-stream processes.

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

    NASA Astrophysics Data System (ADS)

    Sogut, Kenan; Havare, Ali

    2015-12-01

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

  3. 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. 38-39N latitude) is a region of crustal-scale blocks bounded by wedge-shaped depositional-basins and normal-fault systems, here defined as the west-central Walker Lane (WCWL). Devoid of obvious strike-slip faulting, the presence of tectonic-block vertical-axis rotations in the WCWL represents unrecognized components of dextral-shearing and/or changes of strain-accommodation over time. We use paleomagnetic reference directions for Eureka Valley Tuff (EVT) members of the late Miocene Stanislaus Group as spatial and temporal markers for documentation of tectonic-block vertical-axis rotations near Bridgeport, CA. Study-site rotations revealed discrete rotational domains of mean vertical-axis rotation ranging from ~10-30 with heterogeneous regional distribution. Additionally, the highest measured magnitudes of vertical-axis rotation (~50-60 CW) define a 'Region of High Strain' that includes the wedge-shaped Bridgeport Valley (Basin). This study revealed previously-unrecognized tectonic rotation of reference direction sites from prior studies for two (By-Day and Upper) of the three members of the EVT, resulting in under-estimates of regional strain accommodation by these studies. Mean remanent directions and virtual geomagnetic poles utilized in our study yielded a recalculated reference direction for the By-Day member of: Dec.=353.2; Inc.= 43.7; ?95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously unrecognized reference site rotations, and provided an additional reference direction for determining vertical-axis rotation magnitudes. We present a kinematic model based on mean rotation magnitudes of ~30 CW for the Sweetwater Mountains and Bodie Hills that accounts for rotational-strain accommodation of dextral shear in the WCWL since the late Miocene. This model considers rotational magnitudes, paleostrain indicators, edge-effects, and strain-accommodating structures of rotating crustal blocks to represent changes in regional strain accommodation over time. The results and models presented here elucidate the complicated and evolving nature of the WCWL, and further understanding of variations in strain accommodation for the Walker Lane.

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

    NASA Astrophysics Data System (ADS)

    Nadjafikhah, Mehdi; Jafari, Mehdi

    2013-12-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2016-01-22

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

  7. 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

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

    PubMed

    Yang, Chun; Zhi, Xiaoyan; Xu, Hui

    2015-01-01

    A series of novel benzoxazole compounds derived from a naturally occurring neolignan honokiol were prepared. Their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker) in vivo. Most of the tested derivatives exhibited more potential insecticidal activity than their precursor honokiol at the concentration of 1mg/mL. Especially compound 6e, containing 4-acetyloxyphenyl groups at the C8 and C8' positions, displayed the most potent insecticidal activity with the final mortality rate of 62.1%. PMID:25872985

  9. Insight into reduction of obacunone, and their ester derivatives as insecticidal agents against Mythimna separata Walker.

    PubMed

    Yu, Xiang; Ding, Guodong; Zhi, Xiaoyan; Xu, Hui

    2015-01-01

    Here we have prepared a series of ester compounds of obacunone, a naturally occurring limonoid, isolated from plants such as Citrus and Dictamnus angustifolius. Their insecticidal activity was evaluated at 1 mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. When obacunone reacted with NaBH?, the ratio of two reduction products, C7?-hydroxyobacunone (2) and C7?-hydroxyobacunone (3), was related to the reaction mixing solvents. C7?-Propionyloxybacunone (4b) and C7?-(n)heptanoyloxybacunone (5g) exhibited the more promising insecticidal activity than their precursor obacunone and toosendanin. PMID:25465171

  10. 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.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Crasmareanu, Mircea; Frigioiu, Camelia

    2015-07-01

    Fix ? a unitary vector field on a Riemannian manifold M and ? a non-geodesic Frenet curve on M satisfying the Rytov law of polarization optics. We prove in these conditions that ? is a Legendre curve for ? if and only if the ?-Fermi-Walker covariant derivative of ? vanishes. The cases when ? is circle or helix as well as ? 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.

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

    SciTech Connect

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

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Burls, Natalie; Fedorov, Alexey

    2015-04-01

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

  15. 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.

  16. Heat balance and isotopic composition in the tropical tropopause layer (TTL) of a mock- walker circulation

    NASA Astrophysics Data System (ADS)

    Kuang, Z.; Blossey, P. N.; Romps, D. M.

    2008-12-01

    Cloud-resolving model simulations over a large-scale gradient in sea surface temperature (SST), dubbed a mock "Walker" circulation, connects the convection over warm SSTs to the subsiding flow over cooler SSTs and provides a framework for exploring the effects of tropical convection and the large-scale circulation on the TTL. The focus of the present work is on a series of simulations in this framework, performed using the System for Atmospheric Modeling (SAM, Khairoutdinov & Randall 2003) in two-dimensional domains with widths of up to 8192 km, horizontal grid sizes of 1-2 km, and vertical grid sizes of 300-400 m in the tropopause layer. A reverse circulation above the mock-Walker circulation in the troposphere is found, and its effect on the maintenance of the TTL is explored. In addition, simulations that include stable water isotopes (HDO and H218O) of water vapor and all hydrometeors (cloud water, cloud ice, rain, snow and graupel) and their microphysical interactions and fractionation are detailed. The roles of fast (convection) and slow (advection) processes in fixing the fractionation of water vapor in the TTL is explored.

  17. Eupolyphaga sinensis Walker displays inhibition on hepatocellular carcinoma through regulating cell growth and metastasis signaling

    PubMed Central

    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

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

    SciTech Connect

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

    1990-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Rambeau, Joachim; Schehr, Grgory

    2011-06-01

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

  20. 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.

  1. 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.

  2. "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

  3. 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…

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

    ERIC Educational Resources Information Center

    Strully, Jeffrey L.

    2013-01-01

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

  5. Life table studies of rachiplusia nu (guenée) and chrysodeixis (= pseudoplusia) includens (Walker) (lepidoptera: noctuidae) on artificial diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rachiplusia nu (Guenée) and Chrysodeixis (= Pseudoplusia) includens (Walker) (Lepidoptera: Noctuidae) are two economically important species in soybean in northern Argentina. Life cycle, reproductive and population parameters of R. nu and C. includens reared on artificial diet were determined under ...

  6. 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...

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

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  8. 75 FR 19880 - Safety Zone; BW PIONEER at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-16

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

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

    NASA Astrophysics Data System (ADS)

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

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

  10. 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).…

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

    USGS Publications Warehouse

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

    2014-01-01

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

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

    ERIC Educational Resources Information Center

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

    2005-01-01

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

  13. 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.; WinnieHallwachs; J.BollingSullivan

    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

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

    PubMed

    Zhang, Jie; Wang, Xinli

    2016-03-01

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

  15. Constructing the natural hydrograph in order to assess the ecological integrity of Walker River

    NASA Astrophysics Data System (ADS)

    Prancevic, J. P.; Liquori, M.

    2009-12-01

    The Walker River in Nevada and California has served as a major water source for farmers within the Walker River Basin for nearly 150 years. Between 1958-2007, 55%-131% of natural inflows have been diverted from the entire river for irrigation and other anthropogenic uses, while the remainder of the water is delivered to Walker Lake or lost to evapotranspiration and groundwater. These diversions and other land-use practices have altered the river geomorphology, however the altered surface water/groundwater interactions and ecological effects are less clear. This study examines whether the river has retained its functional ecological integrity, despite these diversions, based on 11 specific alteration types for 5 key factors describing the Natural Flow Regime as postulated by Poff et al. (1997): timing, rate of change, frequency, magnitude, and duration. In terms of these factors, we have compared the measured flow regime and an approximation of the natural flow regime in several reaches of the upper river watershed for the years 2001 to 2007. In order to characterize the natural flow regime our study utilizes consumptive use and return flow data as well as characteristic, flow-dependent time scales between reservoirs/diversions and gages. The observed flows are augmented with those flows that are lost to diversions and reservoirs to infer natural flow for a direct comparison. As a whole, 78% of the measures were classified as low or no observed alteration. Generally, the timing of flows has been affected minimally by the diversions at each observed reach. Hydrograph peaks occur at the same time in both regimes and baseflows are consistent with the natural variation in low flows. Low flow durations are typically augmented slightly in the current flow regime, but usually by less than two weeks. For most reaches the snowmelt peak duration was shortened by only a few days, and other peaks (e.g. rain-on-snow) where minimally effected. In all years the rate of change of discharge with respect to time was consistent with rates observed in the natural flow regime on the annual scale, and minimal variations were seen on the storm scale in 2003 (dry) and 2005 (wet). The temporal variation in hydrograph peaks was highly consistent with the natural regime in all years, although slight stabilization occurred during low flows on a daily scale. The duration of peak flows is highly consistent. The most significant impacts include 1) a reduction in magnitude of the peak flows at most reaches, with the scale of reduction increasing downstream, 2) the virtual loss of the snowmelt peak at Wabuska during drought years, which resulted in 3 fewer floods, and 3) modest reductions in flow during the months immediately preceding the snowmelt peak in a few reaches during some years. A significant portion of the effects at Wabuska appears to be influenced by substantial losses to groundwater in Mason Valley. Ongoing research is attempting to refine the contributing factors (including groundwater/surface water interactions) of uncertainty in the natural flow regime. Such data will also have implications for future water management decisions in the Walker River Basin and the ecological effects of further modifications within the basin.

  16. 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.

  17. Detecting brain activation in fMRI using group random walker.

    PubMed

    Ng, Bernard; Hamarneh, Ghassan; Abugharbieh, Rafeef

    2010-01-01

    Due to the complex noise structure of functional magnetic resonance imaging (fMRI) data, methods that rely on information within a single subject often results in unsatisfactory functional segmentation. We thus propose a new graph-theoretic method, "Group Random Walker" (GRW), that integrates group information in detecting single-subject activation. Specifically, we extend each subject's neighborhood system in such a way that enables the states of both intra- and inter-subject neighbors to be regularized without having to establish a one-to-one voxel correspondence as required in standard fMRI group analysis. Also, the GRW formulation provides an exact, unique closed-form solution for jointly estimating the probabilistic activation maps of all subjects with global optimality guaranteed. Validation is performed on synthetic and real data to demonstrate GRW's superior detection power over standard analysis methods. PMID:20879332

  18. 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).

  19. Host-habitat location by the parasitoid, Nasonia vitripennis Walker (Hymenoptera: Pteromalidae).

    PubMed

    Frederickx, Christine; Dekeirsschieter, Jessica; Verheggen, Francois J; Haubruge, Eric

    2014-01-01

    This study investigated the role of odorant cues used during host-habitat location by the generalist parasitoid, Nasonia vitripennis Walker. Nasonia vitripennis is a common parasitoid of Dipteran pupae found in association with decaying carrion. Behavioral assays were used to investigate the host-habitat searching behavior under different scenarios. First, we demonstrated N. vitripennis to be significantly attracted toward odorant cues associated with decaying meat. The biological activity of nine of the volatile molecules constituting the odor of decaying meat was tested on the searching behavior of parasitoid females through two complementary chemoecological approaches: electroantennography (EAG) and olfactometry bioassays. Butanoic acid and butan-1-ol elicited high olfactory responses, but no attraction was induced by these two chemicals. Behavioral assays showed that, among the VOCs tested, methyldisulfanylmethane (DMDS) was the only volatile chemical to induce attraction in N. vitripennis. PMID:23980702

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

    PubMed

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

    2015-11-01

    We report on two families, each with documented consanguinity and two affected with overlapping features of Dandy-Walker malformation, genitourinary abnormalities, intellectual disability, and hearing deficit. This phenotype shares similar findings with many well-known syndromes. However, the clinical findings of this syndrome categorize this as a new syndrome as compared with the phenotype of already established syndromes. Due to parental consanguinity, occurrence in siblings of both genders and the absence of manifestations in obligate carrier parents, an autosomal recessive pattern of inheritance is more likely. The authors believe that these families suggest a novel autosomal recessive cerebello-genital syndrome. Array CGH analyses of an affected did not show pathological deletions or duplications. 2015 Wiley Periodicals, Inc. PMID:26109232

  1. Generalized Nonextensive Thermodynamics Applied to the Cosmic Background Radiation in a Robertson-Walker Universe

    NASA Astrophysics Data System (ADS)

    Hamity, Victor H.; Barraco, Daniel E.

    1996-06-01

    Statistical mechanics is useful to introduce generalizations of standard thermodynamics through the generalization of the entropy and other state functions. Along these lines the Tsallis nonextensive and the Bergmann group symmetric generalizations have proven to be very useful. We combine both formalisms to describe the nonextensive thermostatistics in a relativistic setting. We obtain the generalized forms of the first and second laws of thermodynamics for reversible processes, and apply the resulting theory to the cosmic blackbody radiation in a Robertson-Walker model of the Universe. We show that the temperature of the cosmic blackbody radiation varies as the inverse of the scale factor of the Universe, and is independent of the degree of nonextensivity.

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

    PubMed Central

    Sung, Kyoung-Su

    2014-01-01

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

  3. Feasible domain of Walker's unsteady wall-layer model for the velocity profile in turbulent flows.

    PubMed

    Mikhailov, Mikhail D; Freire, Atila P Silva

    2014-12-01

    The present work studies, in detail, the unsteady wall-layer model of Walker et al. (1989, AIAA J., 27, 140 149) for the velocity profile in turbulent flows. Two new terms are included in the transcendental nonlinear system of equations that is used to determine the three main model parameters. The mathematical and physical feasible domains of the model are determined as a function of the non-dimensional pressure gradient parameter (p+). An explicit parameterization is presented for the average period between bursts (T+B), the origin of time (t+0 ) and the integration constant of the time dependent equation (A0) in terms of p+. In the present procedure, all working systems of differential equations are transformed, resulting in a very fast computational procedure that can be used to develop real-time flow simulators. PMID:25590746

  4. "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

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

    PubMed

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

    2015-12-01

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

  6. Unbiased expectation values from diffusion quantum Monte Carlo simulations with a fixed number of walkers

    NASA Astrophysics Data System (ADS)

    Bos, Ivana; Rothstein, Stuart M.

    2004-09-01

    We append forward walking to a diffusion Monte Carlo algorithm which maintains a fixed number of walkers. This removes the importance sampling bias of expectation values of operators which do not commute with the Hamiltonian. We demonstrate the effectiveness of this approach by employing three importance sampling functions for the hydrogen atom ground state, two very crude. We estimate moments of the electron-nuclear distance, static polarizabilities, and high-order hyperpolarizabilites up to the fourth power in the electric field, where no use is made of the finite field approximation. The results agree with the analytical values, with a statistical error which increases substantially with decreasing overlap of the guiding function with the exact wave function.

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

    PubMed

    Titli?, Marina; Alfirevi?, Stanko; Koli?, Kreimir; Soldo, Anamarija; Tripalol, Ana Bato

    2015-03-01

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

  8. 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.

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

    SciTech Connect

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

    1985-05-01

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

  10. 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.

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

    PubMed

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

    2012-06-01

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

  12. Walker use, but not falls, is associated with lower physical functioning and health of residents in an assisted-living environment

    PubMed Central

    Andersen, Daniel A; Roos, Bernard A; Stanziano, Damian C; Gonzalez, Natasha M; Signorile, Joseph F

    2007-01-01

    The relationship between perceived health and walker use has seldom been addressed. Concerns over falls and falls risk are precursors to walker use. We compared the SF-36 scores of 26 women and 14 men, mean age 86.8 6.0 years based on walker use and faller status. An analysis of covariance (ANCOVA) with age as the covariate, compared groups for the SF-36 constructs and totals score. Significant differences were noted between walker users and nonusers in physical functioning, role limitations due to physical problems, general health, and the total SF-36 score. Pairwise comparisons favored nonusers, while no differences were seen due to faller status. Walker use is associated with lower self-perceptions of physical functioning, role limitations due to physical problems, and general health in assisted-living residents. Faller status is not associated with self-perceived health status. Although walker use aids mobility and lowers the probability of falls, further research is needed to determine if the prescription of assistive devices has a more negative impact on self-perceived health than does falling. This possibility could be explained, in part, by the greater activity levels of those individuals who do not depend on walkers. PMID:18044085

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

    USGS Publications Warehouse

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

    1989-01-01

    Samples of Recent sediments, representing up to 1000 years of accumulation, were collected from three closed basin lakes (Mono Lake, CA, Walker Lake, NV, and Great Salt Lake, UT) to assess the effects of brine composition on the accumulation of total organic carbon, the concentration of dissolved organic carbon, humic acid structure and diagenesis, and trace metal complexation. The Great Salt Lake water column is a stratified Na-Mg-Cl-SO4 brine with low alkalinity. Algal debris is entrained in the high density (1.132-1.190 g/cc) bottom brines, and in this region maximum organic matter decomposition occurs by anaerobic processes, with sulfate ion as the terminal electron acceptor. Organic matter, below 5 cm of the sediment-water interface, degrades at a very slow rate in spite of very high pore-fluid sulfate levels. The organic carbon concentration stabilizes at 1.1 wt%. Mono Lake is an alkaline (Na-CO3-Cl-SO4) system. The water column is stratified, but the bottom brines are of lower density relative to the Great Salt Lake, and sedimentation of algal debris is rapid. Depletion of pore-fluid sulfate, near l m of core, results in a much higher accumulation of organic carbon, approximately 6 wt%. Walker Lake is also an alkaline system. The water column is not stratified, and decomposition of organic matter occurs by aerobic processes at the sediment-water interface and by anaerobic processes below. Total organic carbon and dissolved organic carbon concentrations in Walker Lake sediments vary with location and depth due to changes in input and pore-fluid sulfate concentrations. Nuclear magnetic resonance studies (13C) of humic substances and dissolved organic carbon provide information on the source of the Recent sedimentary organic carbon (aquatic vs. terrestrial), its relative state of decomposition, and its chemical structure. The spectra suggest an algal origin with little terrestrial signature at all three lakes. This is indicated by the ratio of aliphatic to aromatic carbon and the absence of chemical structures indicative of the lignin of vascular plants. The dissolved organic carbon of the Mono Lake pore fluids is structurally related to humic acid and is also related to carbohydrate metabolism. The alkaline pore fluids, due to high pH, solubilize high molecular weight organic matter from the sediments. This hydrophilic material is a metal complexing agent. Despite very high algal productivities, organic carbon accumulation can be low in stratified lakes if the anoxic bottom waters are hypersaline with high concentrations of sulfate ion. Labile organic matter is recycled to the water column and the sedimentary organic matter is relatively nonsusceptible to bacterial metabolism. As a result, pore-fluid dissolved organic carbon and metal-organic complexation are low. ?? 1989.

  14. Crustal Deformation of the Central Walker Lane from GPS velocities: Block Rotations and Slip Rates

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    The Walker Lane is a complex zone of active intracontinental transtension between the Sierra Nevada/Great Valley (SNGV) microplate and the Basin and Range in the western United States. Collectively, this ~100 km wide zone accommodates ~20% of the Pacific-North American relative plate motion. The Central Walker Lane (CWL) extends from the southern boundary of the Mina Deflection (~38.0N) to the latitude of Lake Tahoe (~39.5N) and encompasses the transition from Basin and Range style faulting in the east to the stable block motion of the SNGV microplate in the West. We combine GPS data from the Mobile Array of GPS for Nevada Transtension (MAGNET, http://geodesy.unr.edu/networks) with continuous observations from the EarthScope Plate Boundary Observatory to solve for rates of crustal deformation in the CWL through a block modeling approach. The GPS coordinate time series are derived in this region as part of a 7000-station global network solution using the latest JPL reanalysis of GPS orbits, and the latest antenna models for stations and satellites. The data were processed by precise point positioning using JPL's GIPSY OASIS II software followed by our custom Ambizap3 software, to produce a globally-consistent, ambiguity-resolved network solution. GPS time series in the western United States are rotated into a North America-fixed reference frame and are spatially filtered with respect to the secular motions of reference stations that demonstrate long-term secular stability. In the study region, we use 130 GPS velocities that are corrected for viscoelastic postseismic relaxation following 19th and 20th century earthquakes in the Central Nevada Seismic Belt to constrain rates of long-term fault slip and block rotation. The spatial density and precision of our velocity field (average station spacing of ~20 km with uncertainties well below 1 mm/yr) allow us to compare geodetically estimated slip rates with geologic observations as well as address specific questions about how shear is transferred from the Southern Walker Lane through the Mina Deflection and evaluate along-strike variation of the slip rate on the Sierra Nevada range front fault. Preliminary results confirm a pattern of deformation consistent with geological observations. Deformation zones are characterized by 1) left-lateral slip on east-northeast trending faults and clockwise block rotations in the Mina Deflection, 2) right-lateral slip on northwest trending faults along the eastern margin of the CWL, 3) east-west extension along north trending faults in the western portion of the CWL with right lateral slip increasing toward the SNGV microplate boundary, 4) clockwise rotation of blocks in the Carson Domain, and 5) northwest directed extension in the Basin and Range. Estimates of fault slip rates along the eastern boundary of the SNGV block find that slip is oblique with preliminary rates ranging between 0.4-0.8(0.1) mm/yr horizontal extension and 0.9-1.5(0.1) mm/yr right lateral.

  15. 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 aromatic carbon and the absence of chemical structures indicative of the lignin of vascular plants. The dissolved organic carbon of the Mono Lake pore fluids is structurally related to humic acid and is also related to carbohydrate metabolism. The alkaline pore fluids, due to high pH, solubilize high molecular weight organic matter from the sediments. This hydrophilic material is a metal complexing agent. Despite very high algal productivities, organic carbon accumulation can be low in stratified lakes if the anoxic bottom waters are hypersaline with high concentrations of sulfate ion. Labile organic matter is recycled to the water column and the sedimentary organic matter is relatively nonsusceptible to bacterial metabolism. As a result, pore-fluid dissolved organic carbon and metal-organic complexation are low.

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

    NASA Technical Reports Server (NTRS)

    1953-01-01

    This photo shows the B-29 in the background with Dick Payne, Stan Butchart, and Joe Walker standing in front of it, Charles Littleton and John Moise squatting. The Boeing B-29 was the first U.S. aircraft to be modified to serve as an airborne launch vehicle. Last operated by the NASA High-Speed Flight Station (now the Dryden Flight Research Center, Edwards, California), the B-29 aircraft was used to launch the X-1 series aircraft, including the X-1-1, the X-1-2 (later redesignated the X-1E), the X-1A, and the X-1B. The B-29, which was accepted by the Air Force on Aug. 2, 1945, was operated by the NACA, NASA, the U.S. Air Force, and the Bell Aircraft Company. The Air Force transferred the B-29 to Bell Aircraft Company where it was modified to act as a carrier, or 'mothership,' for the first X-1. After modification, the aircraft flew to Pinecastle Army Air Base, Florida, where it made aeronautical history on Jan. 25, 1946, with its air launch of the first X-1. It then performed 10 drops of the X-1 at Pinecastle before flying to Edwards Air Force Base, California, in September 1946 where it dropped the X-1 for its first powered flight on Dec. 9, 1946. On Oct. 14, 1947, the B-29 again participated in a major aeronautical advance when it air launched the X-1 aircraft, which proceeded to exceed the speed of sound (Mach 1) for the first time. Air Force Pilot Captain Charles 'Chuck' Yeager was at the controls of the X-1 that day. A mid-air explosion in the 'captive' X-1A almost ended the career of the B-29 on Aug. 8, 1955. But pilot Stanley P. Butchart dropped the X-1A to its destruction in the desert after X-1A pilot, Joseph A. Walker, had scrambled back into the B-29. The B-29's 14-year career ended on July 1, 1959, when it was flown from the NASA High-Speed Flight Station to Davis-Monthan Air Force Base, Arizona, for retirement. The aircraft was made obsolete as a mothership by the advent of the X-15 Program, which required a larger, faster launch vehicle, the B-52. In the meantime, from 1950 to 1956, the NACA had used a P2B-1S (a Navy version of the B-29) to launch the rocket-powered versions of the D-558-2 research aircraft.

  17. 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-plate, rocks increases from NW to SE from ~20°, ~50, and up to 90°. Our observations improve on our understanding of the spatial and temporal pattern of deformation and supply the constraints to differentiate coeval and serial translational and rotational deformation histories in this nascent plate boundary zone.

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

    SciTech Connect

    Genereux, D.

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  20. 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.

  1. 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.

  2. Fitness test profiles and trainng intensities in skilled race-walkers.

    PubMed

    Reilly, T; Hopkins, J; Howlett, N

    1979-06-01

    A broad profile of national standard race-walkers was obtained. Subjects were taller and had more body fat than competitive runners of comparable distance as found in the literature. Pulmonary function, blood pressure and maximal heart rates were similar to normal sedentary values. The group's somatotype was 2.5 : 3 : 4, low mesomorphy being reflected in inferior strength measures. Haematological status corresponded to the runners of Brotherhood et al (1975). Predicted VO2 max (x = 70 ml kg min-1) was not related to performance. Time to exhaustion on a treadmill test correlated with 20 km race time (R = -.94; p less than .001). Multiple regression equations derived to predict race performance from combinations of 4 to 6 personality traits were non-significant. Mean heart rate in typical training regimes was 167 beats min-1 for interval training at 13 kmh-1 on the track and 134 beats min-1 over a 2.1 h road walk at 10.3 kmh-1. Physiological strain was greater in uphill than in level or downhill walking (P less than .001). PMID:465913

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

    PubMed Central

    McMillin, MargaretJ.; Beck, AnitaE.; Chong, JessicaX.; Shively, KathrynM.; Buckingham, KatiJ.; Gildersleeve, HeidiI.S.; Aracena, MarianaI.; Aylsworth, ArthurS.; Bitoun, Pierre; Carey, JohnC.; Clericuzio, CarolL.; Crow, YanickJ.; Curry, CynthiaJ.; Devriendt, Koenraad; Everman, DavidB.; Fryer, Alan; Gibson, Kate; GiovannucciUzielli, MariaLuisa; Graham, JohnM.; Hall, JudithG.; Hecht, JacquelineT.; Heidenreich, RandallA.; Hurst, JaneA.; Irani, Sarosh; Krapels, IngridP.C.; Leroy, JulesG.; Mowat, David; Plant, GordonT.; Robertson, StephenP.; Schorry, ElizabethK.; Scott, RichardH.; Seaver, LaurieH.; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, SehimeG.; Weaver, DavidD.; Whiteford, Margo; Williams, MarcS.; Tabor, HollyK.; Smith, JoshuaD.; Shendure, Jay; Nickerson, DeborahA.; Bamshad, MichaelJ.

    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 (Fishers 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

  4. Airborne SAR determination of relative ages of Walker Valley moraines, eastern Sierra Nevada

    NASA Technical Reports Server (NTRS)

    Fox, A.; Isacks, B.; Bloom, A.; Fielding, E.; Mcmurry, D.

    1991-01-01

    A regional study of the distribution and elevations of Pleistocene moraines in the Andes requires a method of determining relative age from space. One of our primary objectives is to establish the relative chronology of major climatic events responsible for glaciation in the Andes and other regions that are difficult to access on the ground and where suitable material for absolute age determination is lacking. The sensitivity of radar to surface roughness makes it possible to develop a remotely-based relative dating technique for landforms for which surface age and roughness can be correlated. We are developing such a technique with Airborne Synthetic Aperture Radar (AIRSAR) imagery of the eastern Sierra Nevada where independent evidence is available for the ages and physical characteristics of moraines. The Sierra Nevada moraines are similar in form and environmental setting to Andean moraines that we have targeted for study during the pending Shuttle Imaging Radar-C (SIR-C) mission. SAR imagery is used to differentiate the ages of five moraine sequences of Walker Valley in the eastern Sierra Nevada. Other aspects of this investigation are briefly discussed.

  5. Field studies of streamflow generation using natural and injected tracers on Bickford and Walker Branch Watersheds

    SciTech Connect

    Genereux, D.; Hemond, H. . Dept. of Civil Engineering); 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.

  6. Population decrease of Scirpophaga incertulas Walker (Lepidoptera Pyralidae) under climate warming

    PubMed Central

    Shi, Peijian; Zhong, Ling; Sandhu, Hardev S; Ge, Feng; Xu, Xiaoming; Chen, Wei

    2012-01-01

    Scirpophaga incertulas Walker is an important agricultural pest in Asia. Only few studies are available on its long-term population dynamics under climate warming. In this study, we used the linear and generalized additive models (GAMs) to analyze the historical dataset of >50 years on this pest at Xinfeng County of Jiangxi Province, China. The main objective of this study was to explore the effects of density (delayed) dependence and minimum annual temperature (MAT), which indirectly reflects climate warming, on the population dynamics of this pest. We found that both density dependence and MAT have significant influence on the annual population growth rate. The GAMs had relatively better applicability to the dataset than the linear models. Nonparametric model provided satisfactory goodness-of-fit (R2 > 0.5). At Xinfeng County, the MAT had a significant effect on the annual population growth rate of S. incertulas. The annual population growth rate of S. incertulas decreased with increase in MAT. Therefore, S. incertulas population becomes smaller and smaller in Southern China due to climate warming. The current study has two contributions: (1) providing a suitable method for predicting the annual population growth rate of S. incertulas, and (2) demonstrating that climate warming could decrease the S. incertulas population. PMID:22408726

  7. Increased nitric oxide levels in cerebellum of cachectic rats with Walker 256 solid tumor.

    PubMed

    Fenner, Fabio Leandro; Guarnier, Flavia Alessandra; Bernardes, Sara Santos; Ramalho, Leandra Naira Zambelli; Cecchini, Rubens; Cecchini, Alessandra Lourenço

    2015-01-01

    In cancer cachexia, the role of nitric oxide (NO) in the central nervous system remains unclear. Cerebellar degeneration has been reported in cancer patients, but the participation of NO has not been studied. Thus, this study investigated the mechanism of oxidative cerebellar injury in a time-course cancer cachexia experimental model. The cachexia index is progressive and evident during the evolution of the tumor. Nitric oxide and lipid hydroperoxidation quantification was performed using a very sensitive and precise chemiluminescence method, which showed that both analyzed parameters were increased after tumor implantation. In the day 5 group, NO was significantly increased, and this experimental time was chosen to treat the rats with the NO inhibitors N-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG). When treated with NO inhibitors, a significant decrease in both NO and lipid hydroperoxide levels occurred in the cerebellum. 3-nitrotyrosine was also analyzed in cerebellar tissue by immunohistochemistry; it was increased at the three experimental time points studied, and decreased when treated with L-NAME and AG. Besides demonstrating that lipid hydroperoxidation in the cerebellum of rats with cachexia increases in a time-dependent manner, this study is the first to describe the participation of NO and its oxidized product 3-NT in the cerebellum of cachectic rats bearing the Walker 256 solid tumor. PMID:26216116

  8. Long-term follow-up of successful treatment for dandy-walker syndrome (DWS)

    PubMed Central

    Lin, Jun; Liang, Guobiao; Liang, Yong; Kou, Yun

    2015-01-01

    Background: Various managements of Dandy-Walker syndrome (DWS) from open excision of the cysts to CSF diversion have been reported. However, optimal treatment for DWS remains elusive. Methods: Cyst fenestration was employed firstly, but failed 15 days after the surgery. Then a ventriculoperitoneal (VP) shunt was inserted and the patient discharged from hospital 13 days after the second surgery. During the 12-year follow-up, CT scanning, MRI, and X-radiation were performed. Results: CT scanning showed that the size of ventricular system gradually returned to normal. MRI revealed similar changes of the ventricular system, and further revealed the development of supratentorial brain. The results of X-radiation during the follow-up years showed that the peritoneal end of the shunt might be already out of the abdominal cavity. Slow refilling of the shunt valve may suggest that the shunt could be probably not functional. Conclusion: The treatment of the patient was successfully, and the abnormal cerebral ventricle system gradually recovered during the 12-year follow-up. Because the patient might be probably independent on the shunt, further choice of the shunt removal should be thinking thoroughly, considering both safety and quality of life for the patient.

  9. Procion dyes as affinity ligands and reporter groups for dihydrofolate reductase from Walker 256 carcinoma.

    PubMed

    Johnson, S J; Stevenson, K J; Gupta, V S

    1980-11-01

    Procion dye - agarose matrices were investigated for isolation of dihydrofolate reductase (FAH2R) from Walker 256 carcinosarcoma. Cibacron blue F3GA, Procion blue MX4GD, Procion blue HERD, and Procion red H3BN covalently bound to agarose adsorbed greater than 85% of pure FAH2R from 100 mM imidazole buffer, pH 6.3, and this enzyme was specifically and quantitatively eluted with 1 mM folate. The capacity and selectivity of the dye-agarose matrices were greater at low dye incorporation. Difference spectroscopy of the FAH2R - Cibacron blue F3GA complex indicated that 2 mol of the dye were bound in hydrophobic environments with each mole of the enzyme. NADPH and folate (at twofold molar excess over enzyme) or 1 M KCl displaced only 1 mol of Cibacron blue F3GA. This dye interacted stoichiometrically in a specific manner with the active site of FAH2R probably spanning the folate and NADP binding sites. The second dye molecule appears to be bound in a nonspecific hydrophobic manner. Selected Procion dye - agarose matrices can be used for partial purification of FAH2R from tumor homogenate. PMID:7214192

  10. Uniqueness of complete maximal hypersurfaces in spatially parabolic generalized Robertson-Walker spacetimes

    NASA Astrophysics Data System (ADS)

    Romero, Alfonso; Rubio, Rafael M.; Salamanca, Juan J.

    2013-06-01

    A new technique for the study of noncompact complete spacelike hypersurfaces in generalized Robertson-Walker (GRW) spacetimes whose fiber is a parabolic Riemannian manifold is introduced. This class of spacetimes allows us to model open universes which extend to spacelike closed GRW spacetimes from the viewpoint of the geometric analysis of the fiber, and which, unlike those spacetimes, could be compatible with the holographic principle. First, under reasonable assumptions on the restriction of the warping function to the spacelike hypersurface and on the hyperbolic angle between the unit normal vector field and a certain timelike vector field, a complete spacelike hypersurface in a spatially parabolic GRW spacetime is shown to be parabolic, and the existence of a simply connected parabolic spacelike hypersurface in a GRW spacetime also leads to the parabolicity of its fiber. Then, all the complete maximal hypersurfaces in spatially parabolic GRW spacetimes are determined in several cases, extending, in particular, to this family of open cosmological models several well-known uniqueness results for the case of spatially closed GRW spacetimes. Moreover, new Calabi-Bernstein problems are solved.

  11. 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.

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

    PubMed Central

    Yan, Hong; Sun, Liguang; Oppo, Delia W.; Wang, Yuhong; Liu, Zhonghui; Xie, Zhouqing; Liu, Xiaodong; Cheng, Wenhan

    2011-01-01

    The relative importance of northsouth migrations of the intertropical convergence zone (ITCZ) versus El Nio-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that northsouth ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability profoundly influenced tropical Pacific hydrology. We present hydrological reconstructions from Cattle Pond, Dongdao Island of the South China Sea, where multi-decadal rainfall and downcore grain size variations are correlated to the Southern Oscillation Index during the instrumental era. Our downcore grain size reconstructions indicate that this site received less precipitation during relatively warm periods, AD 10001400 and AD 18502000, compared with the cool period (AD 14001850). Including our new reconstructions in a synthesis of tropical Pacific records results in a spatial pattern of hydrologic variability that implicates the PWC. PMID:21522137

  13. Endotoxin, epinephrine, and ellagic acid effects on the radiation-sensitized walker 256 rat carcinosarcoma.

    PubMed

    Contreras, M D; Bale, W F

    1968-10-01

    A radiation exposure of 1500 R to the Walker 256 rat tumor was found to sensitize this tumor to the effect of a sublethal dose of endotoxin (Sarratia marcescens lipopolysaccharide) given 2 days later so that complete or almost complete destruction of the tumor resulted. Histological. study showed rapidly developing massive necrosis of tumor tissue. Tracer experiments with 131I-labeled antibody to rat fibrin indicated an absence of blood circulation in the treated tumor. These results suggest that the lesion may be secondary to blood coagulation occurring in the vascular bed of the tumor. Apparently identical lesions were also produced by epinephrine and ellagic acid, alone or in combination. It is known that even untreated tumors are often the site of fibrin deposition. Presumably radiation, by injury to tumor cells, enhances the release of coagulation-producing substances into the vascular bed. It is postulated that the effect of subsequent treatment with the drugs listed above is produced by circulatory stasis induced in the tumor. This may be associated with Hageman factor activation or release of platelet factor 3. PMID:17387937

  14. 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.

  15. The Non-Diagonal Models of the Robertson-Walker Universe in General Relativity

    NASA Astrophysics Data System (ADS)

    Beloushko, Konstantin; Karbanovski, Valeri; Belenkova, Anastasiya

    As is known, the Robertson-Walker metric describe a homogeneous and isotropic universe. For this metric recorded in diagonal form, the equations of general relativity (GR) give the energy-momentum tensor (EMT), which will also have a diagonal form. In [1] it was shown that nondegenerate coordinate transformations can lead metric to non-diagonal mean that allows to get non-diagonal components of the EMT. This allows: begin{enumerate} build a model of the Universe of "ordinary" matter without resorting to the "exotic"; enter into the model the observed cosmic microwave background, which correspond to non-diagonal components of the EMT (energy flux density and components of stress tensor); reconcile heterogeneous distribution of matter with overall homogeneity of space-time geometry. The task of constructing the model is reduced to the choice of the type of metric functions, which will ensure the implementation of the standard physical conditions and allowed to clarify the evolution of the universe. Reference begin{enumerate} V.V. Karbanovski et al. - JETP, 112 (2011), 60.

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

    PubMed

    Roy, Manidipa; Barman, Soma

    2016-01-10

    Spectral analysis using Fourier techniques is popular with gene prediction because of its simplicity. Model-based autoregressive (AR) spectral estimation gives better resolution even for small DNA segments but selection of appropriate model order is a critical issue. In this article a technique has been proposed where Yule-Walker autoregressive (YW-AR) process is combined with principal component analysis (PCA) for reduction in dimensionality. The spectral peaks of DNA signal are used to detect protein-coding regions based on the 1/3 frequency component. Here optimal model order selection is no more critical as noise is removed by PCA prior to power spectral density (PSD) estimation. Eigenvalue-ratio is used to find the threshold between signal and noise subspaces for data reduction. Superiority of proposed method over fast Fourier Transform (FFT) method and autoregressive method combined with wavelet packet transform (WPT) is established with the help of receiver operating characteristics (ROC) and discrimination measure (DM) respectively. PMID:26385320

  17. New Test of the Friedmann-Lematre-Robertson-Walker Metric Using the Distance Sum Rule

    NASA Astrophysics Data System (ADS)

    Rsnen, Syksy; Bolejko, Krzysztof; Finoguenov, Alexis

    2015-09-01

    We present a new test of the validity of the Friedmann-Lematre-Robertson-Walker (FLRW) metric, based on comparing the distance from redshift 0 to z1 and from z1 to z2 to the distance from 0 to z2. If the Universe is described by the FLRW metric, the comparison provides a model-independent measurement of spatial curvature. The test relies on geometrical optics, it is independent of the matter content of the Universe and the applicability of the Einstein equation on cosmological scales. We apply the test to observations, using the Union2.1 compilation of supernova distances and Sloan Lens ACS Survey galaxy strong lensing data. The FLRW metric is consistent with the data, and the spatial curvature parameter is constrained to be -1.22

  18. 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.

  19. Fitness test profiles and trainng intensities in skilled race-walkers.

    PubMed Central

    Reilly, T.; Hopkins, J.; Howlett, N.

    1979-01-01

    A broad profile of national standard race-walkers was obtained. Subjects were taller and had more body fat than competitive runners of comparable distance as found in the literature. Pulmonary function, blood pressure and maximal heart rates were similar to normal sedentary values. The group's somatotype was 2.5 : 3 : 4, low mesomorphy being reflected in inferior strength measures. Haematological status corresponded to the runners of Brotherhood et al (1975). Predicted VO2 max (x = 70 ml kg min-1) was not related to performance. Time to exhaustion on a treadmill test correlated with 20 km race time (R = -.94; p less than .001). Multiple regression equations derived to predict race performance from combinations of 4 to 6 personality traits were non-significant. Mean heart rate in typical training regimes was 167 beats min-1 for interval training at 13 kmh-1 on the track and 134 beats min-1 over a 2.1 h road walk at 10.3 kmh-1. Physiological strain was greater in uphill than in level or downhill walking (P less than .001). PMID:465913

  20. Staurosporine shows insecticidal activity against Mythimna separata Walker (Lepidoptera: Noctuidae) potentially via induction of apoptosis.

    PubMed

    Zhang, Yang; Liu, Songlin; Yang, Xing; Yang, Mingjun; Xu, Wenping; Li, Yaxiao; Tao, Liming

    2016-03-01

    Staurosporine (STS), a wide-spectrum kinase inhibitor, is widely used in studies of apoptosis in mammalian cells. However, its physiological and mechanistic effects have never been clearly defined in insect cells, and other applications of STS have rarely been reported. The present study reveals the insecticidal activity of STS on larvae of Mythimna separata Walker, and the apoptotic mechanism induced by STS on lepidopteran Sf9 cell lines. We demonstrate that the viability of Sf9 cells is inhibited by STS in a time- and concentration-dependent manner. Intracellular biochemical assays show that STS-induced apoptosis of Sf9 cells coincides with a decrease in the mitochondrial membrane potential, the release of cytochrome c into the cytosol, a significant increase of the Bax/Bcl-2 ratio, and a marked activation of caspase-9 and caspase-3. These results indicate that a mitochondrial-dependent intrinsic pathway contributes to STS induced caspase-3 activation and apoptosis in Sf9 cells which is homologous to the mechanisms in mammalian cells. This study contributes to our understanding of the mechanism of insect cell apoptosis and suggests a possible new application of STS as a potential insecticide against Lepidopteran insect pests in agriculture. PMID:26969438

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

    PubMed

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

    2015-03-01

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

  2. Mechanics and kinetics in the Friedmann-Lematre-Robertson-Walker space-times

    NASA Astrophysics Data System (ADS)

    Kelner, S. R.; Prosekin, A. Yu.; Aharonian, F. A.

    2011-08-01

    Using the standard canonical formalism, the equations of mechanics and kinetics in the Friedmann-Lematre-Robertson-Walker (FLRW) space-times in Cartesian coordinates have been obtained. The transformation law of the generalized momentum under the shift of the origin of the coordinate system has been found, and the form invariance of the Hamiltonian function relative to the shift transformation has been proved. The derived equations allow one to shift the origin of the coordinate system to the point of location of the observer. The space in the vicinity of this point can be considered as a Euclidean one which makes straightforward the interpretation of calculations. For the distribution function in the phase space, the general solution of the collisionless Boltzmann equation has been found. The results of this work can be used for treatment of evolution of the distribution function of particles arriving from the cosmologically distant objects. We discuss, in particular, two important cases of astrophysical interest: (i) the homogenous distribution particles taking into account energy losses, and (ii) the spherically symmetric case with arbitrary angular distribution. While the first problem is linked to the diffuse distributions of particles produced at cosmological epochs, the second one is relevant to the discrete astrophysical objects.

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

    PubMed Central

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

    2009-01-01

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

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

    PubMed

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

    2015-11-01

    Spilarctia obliqua Walker (Lepidoptera: Arctiidae) is a polyphagous insect pest damaging pulses, oil seeds, cereals, vegetables and medicinal and aromatic plants in India. The pest also infests turmeric and ginger sporadically in Kerala. We observed an epizootic caused by a nucleopolyhedrovirus (NPV) in field populations of the insects in December 2013. The NPV was purified and characterized. The isolate was tetrahedral in shape and belonged to multicapsid NPV. The REN profile of the SpobNPV genome with Pst I, Xho I and HindIII enzymes showed a genome size of 99.1±3.9 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

  5. Automatic detection of lift-off and touch-down of a pick-up walker using 3D kinematics.

    PubMed

    Grootveld, L; Thies, S B; Ogden, D; Howard, D; Kenney, L P J

    2014-02-01

    Walking aids have been associated with falls and it is believed that incorrect use limits their usefulness. Measures are therefore needed that characterize their stable use and the classification of key events in walking aid movement is the first step in their development. This study presents an automated algorithm for detection of lift-off (LO) and touch-down (TD) events of a pick-up walker. For algorithm design and initial testing, a single user performed trials for which the four individual walker feet lifted off the ground and touched down again in various sequences, and for different amounts of frame loading (Dataset_1). For further validation, ten healthy young subjects walked with the pick-up walker on flat ground (Dataset_2a) and on a narrow beam (Dataset_2b), to challenge balance. One 88-year-old walking frame user was also assessed. Kinematic data were collected with a 3D optoelectronic camera system. The algorithm detected over 93% of events (Dataset_1), and 95% and 92% in Dataset_2a and b, respectively. Of the various LO/TD sequences, those associated with natural progression resulted in up to 100% correctly identified events. For the 88-year-old walking frame user, 96% of LO events and 93% of TD events were detected, demonstrating the potential of the approach. PMID:24035573

  6. Regression of Walker 256 carcinosarcoma in vasopressin-deficient Brattleboro rats is accompanied by a changed laminin pattern.

    PubMed

    Khegay, Igor I; Ivanova, Ludmila N

    2015-04-01

    Walker 256 carcinosarcoma is a transplantable model of rat carcinoma that originally appeared spontaneously in mammary glands. The growth rate of Walker 256 carcinosarcoma in vasopressin-deficient Brattleboro rats is lower than in WAG rats and their congenic hybrids with normal vasopressin levels. Study of tumor proteins detected essential alterations. Tumor regression starting at the 14th day in Brattleboro rats was accompanied by changes in the laminin pattern. At the 21st day, the concentration of ?-chains became twice as low, while ?-chains of laminin showed a sixfold increase compared to the initial equimolar correlation of bands. Congenic hybrids having one active copy of the vasopressin gene to provide a physiological level of hormone against the genetic background of Brattleboro rats show the same laminin alterations as WAG rats. They demonstrated a similar moderate increase of ?-chains and threefold growth of ?- and ?-chains of laminin in tumor tissue. It is supposed that vasopressin may be involved in the regulation of relevant local stimuli to trigger renovation of the laminin composition in a course of growing Walker 256 carcinosarcoma. PMID:25854851

  7. 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, Ramn; 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

  8. Pilot Joe Walker in Lunar Landing Research Vehicle (LLRV) on ramp

    NASA Technical Reports Server (NTRS)

    1964-01-01

    In this 1964 NASA Flight Research Center photograph, NASA Pilot Joe Walker is setting in the pilot's platform of the the Lunar Landing Research Vehicle (LLRV) number 1. This photograph provides a good view of the pilot setting in front of the primary instrumentation panel. When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon's surface. Three concepts surfaced: an electronic simulator, a tethered device, and the ambitious Dryden contribution, a free-flying vehicle. All three became serious projects, but eventually the NASA Flight Research Center's (FRC) Landing Research Vehicle (LLRV) became the most significant one. Hubert M. Drake is credited with originating the idea, while Donald Bellman and Gene Matranga were senior engineers on the project, with Bellman, the project manager. Simultaneously, and independently, Bell Aerosystems Company, Buffalo, N.Y., a company with experience in vertical takeoff and landing (VTOL) aircraft, had conceived a similar free-flying simulator and proposed their concept to NASA headquarters. NASA Headquarters put FRC and Bell together to collaborate. The challenge was; to allow a pilot to make a vertical landing on earth in a simulated moon environment, one sixth of the earth's gravity and with totally transparent aerodynamic forces in a 'free flight' vehicle with no tether forces acting on it. Built of tubular aluminum like a giant four-legged bedstead, the vehicle was to simulate a lunar landing profile from around 1500 feet to the moon's surface. To do this, the LLRV had a General Electric CF-700-2V turbofan engine mounted vertically in gimbals, with 4200 pounds of thrust. The engine, using JP-4 fuel, got the vehicle up to the test altitude and was then throttled back to support five-sixths of the vehicle's weight, simulating the reduced gravity of the moon. Two hydrogen-peroxide lift rockets with thrust that could be varied from 100 to 500 pounds handled the LLRV's rate of descent and horizontal translations. Sixteen smaller hydrogen-peroxide rockets, mounted in pairs, gave the pilot control in pitch, yaw, and roll. On the LLRV, in case of jet engine failure, six-500-pounds-of thrust rockets could be used by the pilot to carefully apply lift thrust during the rapid descent to hopefully achieve a controllable landing. The pilot's platform extended forward between two legs while an electronics platform, similarly located, extended rearward. The pilot had a zero-zero ejection seat that would then lift him away to safety. Weight and balance design constraints were among the most challenging to meet for all phases of the program (design, development, operations). The two LLRVs were shipped disassembled from Bell to the FRC in April 1964, with program emphasis placed on vehicle No. 1. The scene then shifted to the old South Base area of Edwards Air Force Base. On the day of the first flight, Oct. 30, 1964, NASA research pilot Joe Walker flew it three times for a total of just under 60 seconds, to a peak altitude of approximately 10 feet. By mid-1966 the NASA Flight Research Center had accumulated enough data from the LLRV flight program to give Bell a contract to deliver three Lunar Landing Training Vehicles (LLTVs) at a cost of $2.5 million each. As 1966 ended, the LLRV #1 had flown 198 flights, and the LLRV #2 was being assembled, instrumented and cockpit modifications made at the South Base. The first flight of the number two LLRV in early January 1967 was quickly followed by five more. In December 1966 vehicle No. 1 was shipped to Houston, followed by No. 2 in mid January 1967. When Dryden's LLRVs arrived at Houston they joined the first of the LLTVs to eventually make up the five-vehicle training and simulator fleet. All five vehicles were relied on for simulation and training of moon landings.

  9. Walker Lake 1/sup 0/ x 2/sup 0/ NTMS area California and Nevada: data report

    SciTech Connect

    Fay, W.M.; Jones, P.L.

    1980-03-01

    This data report presents results of ground water and stream sediment reconnaissance in the National Topographic Map Series (NTMS) Walker Lake 1/sup 0/ x 2/sup 0/ quadrangle. Surface sediment samples were collected at 797 sites or at a nominal density of one site per 20 square kilometers (eight square miles). Ground water samples were collected at 77 sites or at a nominal density of one site per 220 square kilometers (87 square miles). Neutron activation analysis (NAA) results are given for uranium and 16 other elements in sediments, and for uranium and 8 other elements in ground water. Mass spectrometry results are given for helium in ground water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Statistical summaries of data and a brief description of results are given. A generalized geologic map and a summary of the geology of the area are included. Data from ground water sites (on microfiche in pocket) include (1) water chemistry measurements (pH, conductivity, and alkalinity), (2) physical measurements (water temperature, well description, and scintillometer reading), and (3) elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na, and V). Data from sediment sites (also on microfiche in pocket) include (1) water chemistry measurements (pH, conductivity, and alkalinity), and (2) elemental analyses (U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors (stream characteristics, vegetation, etc.) are also tabulatedn Symbol plot maps, histograms, and cumulative frequency plots for most elements, U/Th and U/Hf ratios, and scintillometer readings are included on the microfiche.

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

    PubMed Central

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

    2013-01-01

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

  11. Bioactivity-guided isolation of antiplasmodial constituents from Conyza sumatrensis (Retz.) E.H. Walker.

    PubMed

    Boniface, Pone Kamdem; Verma, Surjeet; Shukla, Aparna; Cheema, Harveer Singh; Srivastava, Santosh Kumar; Khan, Feroz; Darokar, Mahendra Pandurang; Pal, Anirban

    2015-02-01

    Conyza sumatrensis (Retz.) E.H. Walker (Cs) leaves are used for traditional treatment of malaria in Cameroon. However, the antimalarial activity of the leaf constituents of this plant is still unexplored. The aim of our investigation was to evaluate the antiplasmodial activity of some bioactive constituents from Cs leaves. Compounds were isolated from Cs leaves and structurally elucidated using extensive spectroscopic analysis. The in vitro antiplasmodial activity of the extracts and pure compounds were evaluated on chloroquine-sensitive strain (NF54) of Plasmodium falciparum. The in vivo assay was done by administering seven doses of extracts in mice infected with Plasmodium berghei K173 through oral route. Cytotoxicity of pure compounds on murine macrophage cells was performed through [3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide] (MTT) test. Hemolysis and lactate dehydrogenase assays were also carried out using standard procedures. The in silico prediction of bioactive constituents was performed through Autodock Vina. Polarity-based extracts from Cs were found to be active against P. falciparum (NF54) and P. berghei (K173) in vitro and in vivo respectively. Further, bioactivity-guided isolation of n-hexane fraction yielded three compounds, (1), (2) and (3) with IC50 of 34, 17.9 and 18?g/ml, respectively, while the ethyl acetate fraction afforded the fourth compound with an IC50 of 25?g/ml, indicating anti-malarial potential of Cs through PfLDH interaction without compromising normal cell growth. This study reports for the first time, the antiplasmodial activity of bioactive constituents from Cs and confirms its traditional use. PMID:25449289

  12. Mutations in POMT1 are found in a minority of patients with Walker-Warburg syndrome.

    PubMed

    Currier, Sophie C; Lee, Christine K; Chang, Bernard S; Bodell, Adria L; Pai, G Shashidhar; Job, Leela; Lagae, Lieven G; Al-Gazali, Lihadh I; Eyaid, Wafaa M; Enns, Greg; Dobyns, William B; Walsh, Christopher A

    2005-02-15

    Walker-Warburg syndrome (WWS) is an autosomal recessive disorder of infancy characterized by hydrocephalus, agyria, retinal dysplasia, congenital muscular dystrophy, and over migration of neurons through a disrupted pial surface resulting in leptomeningeal heterotopia. Although previous work identified mutations in the o-mannosyl transferase, POMT1, in 6 out of 30 WWS families [Beltran-Valero de Bernabe et al., 2002], the incidence of POMT1 mutations in WWS is not known. We sequenced the entire coding region of POMT1 in 30 consecutive, unselected patients with classic WWS. Two novel heterozygous mutations were found in two patients from non-consanguineous parents, whereas 28 other patients failed to show any POMT1 mutations. One patient was found to be heterozygous for a transition, g.1233T > A, which predicts p.Y352X. A second patient was found also to be heterozygous for a transition g.1790C > G, which predicts p.S537R. As an additional determination of the frequency of the POMT1 mutations in WWS, we tested for linkage of WWS to POMT1 in six consanguineous families. All six demonstrated heterozygosity and negative LOD scores at the POMT1 locus. From these data we show that POMT1 is an uncommon cause of WWS, the incidence of coding region mutations in this population of WWS being less than 7%. We conclude that while the incidence of POMT1 mutations in WWS can be as high as 20% as reported by Beltran-Valero de Bernabe et al. [2002] and it can be as low as approximately 7%, as reported here. PMID:15637732

  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. 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.

  15. 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.

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

    SciTech Connect

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

    2011-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Kaya, Ali; Tarman, Merve

    2011-04-01

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

  18. Mass balance of trace elements in Walker branch watershed: relation to coal-fired steam plants.

    PubMed Central

    Lindberg, S E; Andren, A W; Raridon, R J; Fulkerson, W

    1975-01-01

    A mass balance study of trace element flows at the TVA Allen Steam Plant at Memphis showed that most of the released Hg, some Se, and probably most Cl and Br are discharged to the atmosphere as gases. The elements As, Cd, Cu, Ga, Mo, Pb, Sb, Se, and Zn were concentrated in fly ash compared to slag and were more concentrated in the ash discharged through the stack than in that collected by the precipitator, while Al, Ba, Ca, Ce, Co, Eu, Fe, Hf, K, La, Mg, Mn, Rb, Sm, Sr, Ta, Th, and Ti showed little preferential partitioning between the slag and the collected or discharged fly ash. The elements Cr, Cs, Na, Ni, U, and V exhibited behavior intermediate between the latter two groups. This information about stack emissions of trace elements from the Allen Plant was used to estimate the likely range of air concentrations and input (dry and wet deposition) to the Walker Branch Watershed. The watershed, which is on the ERDA reservation at Oak Ridge, is within 20 km of three coal-fired steam plants, two in the TVA system and one belonging to ERDA. The estimated input values are compared to measurements of Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn in wet precipitation falling on the watershed during 1973 and 1974. Dry deposition of these elements could not be measured directly but estimates indicated that this could be of the same order of magnitude as the rainwater input. A six-month mass balance indicated that the watershed efficiently retains Pb (97-98% of the atmospheric input,) Cu (82-84%), while Cr (69%), Mn (57%), Zn (73%), and Hg (69%) are less well retained. Images FIGURE 3. PMID:1227866

  19. On mechanisms that drive Walker type circulations within the context of a general circulation model. Ph.D. Thesis

    SciTech Connect

    Avila, L.A.

    1993-01-01

    The so-called east-west cells of the global tropics observed by Madden and Julian were documented within the context of the Community Climate Model. There was a substantial agreement between observations and the simulated east-west cells. A comparison of a no-mountain experiment with a control run revealed the contribution of the orography to the location and strength of the upward branch of the Walker cell. It was found that the mountains indirectly enhanced the upper level divergence and the uplifting over the Maritime Continent through the position of the Asian Jet. The model sensitivity to SST was studied by analyzing a run with prescribed SST anomalies which are representative of a mature phase of `El Nino` episode. The analysis included another run with prescribed warm SST anomalies over the eastern Pacific. Both simulations were successful in reproducing anomalous Walker cells over the region of warm SST and convective heating. The importance of global moisture and local evaporation was evaluated through a set of experiments in which the evaporation was suppressed either globally or over regions of maximum uplifting over Indonesia. For the case of the evaporation globally suppressed the resulting circulation consisted of a giant seabreeze with ascending and descending branches over the hot land and cooler ocean respectively. For the case of evaporation gradually reduced over Indonesia, the model responded with a substantial decrease in the uplifting and rainfall there, suggesting that local evaporation was the primary mechanism for initiating precipitation. Correlations among the moisture budget fields reaffirmed the importance of local evaporation in producing precipitation in the ascending branch of the Walker cell.

  20. Evidence for Interannual to Decadal Variations in Hadley and Walker Circulations and Links to Water and Energy Fluxes

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin; Bosilovich, Michael; Miller, Timothy

    2007-01-01

    Mass and energy transports associated with the Hadley and Walker circulations are important components of the earth s climate system and are strongly linked to hydrologic processes. Interannual to decadal variation in these flows likely signify a combination of natural climate noise as well as a response to anthropgenic forcing. There remains considerable uncertainty in quantifying variations in these flows. Evidence in the surface pressure record supports a weakening of the Walker circulation over the Pacific in recent decades. Conversely the NCEP / NCAR and ERA 40 reanalyses indicate that the Hadley circulation has increased in strength over the last two decades, though these analyses depict significantly different mass circulation changes. Interestingly, the NCEP - II / DOE reanalysis contains essentially no Hadley circulation changes. Most climate model integrations anticipate a weakening of both tropical circulations associated with stronger static stability. Clearly there is much uncertainty not only with the mass transports, but also how they are linked to water and energy balance of the planet through variations in turbulent heat and radiative fluxes and horizontal exports / imports of energy. Here we examine heat and water budget variations from a number of reanalysis products and focus on the linear and nonlinear response of ENSO warm and cold events as opportunities to study budget variations over the past 15-20 years. Our analysis addresses such questions as To what extent do Hadley and Walker Cell variations compensate each other on mass and energy transport? Do static stability adjustments appear to constrain fractional precipitation response vs. fractional water vapor response? We appeal to constraints offered by GPCP precipitation, SSWI ocean evaporation estimates, and ISCCP-FD radiative fluxes, and other satellite data sets to interpret and confirm reanalysis-based diagnostics. Using our findings we also attempt to place in context the recent findings that tropical ocean evaporation increased by order 5% or more during the 1990s, reconciling this with GPCP precipitation variations.

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

    PubMed

    Lamnica, Dionsia Aparecida Cusin; Ferraz, Plnio Marcos Duarte Pinto; Ferreira, Amanda Tragueta; Prado, Lvia Maria do; Abramides, Dagma Venturini Marquez; Gejo, 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

  2. 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 Groups 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, 9.420.04 Ma, 2D) Upper Member of EVT 9.430.02 Ma, and 3) Dardanelle Formation, composed of latite lavas, which caps the Stanislaus Group. Because of wide areal distribution across the central Walker Lane, we have used members of the Stanislaus Group to evaluate and understand regional strain in this part of the North American-Pacific plate boundary, which currently accommodates ~25% of relative dextral plate motion. Paleomagnetic analysis has yielded multiple reference remanence directions for elements of the Stanislaus Group on the relatively stable Sierra Nevada microplate for comparison with those same units deposited within the extensively-faulted Walker Lane to the east. Preliminary results show tectonic domains near Bridgeport, CA in the 5-10 km size range displaying eastward-increasing vertical-axis block rotation. This west-to-east increase in rotation appears to sub-parallel the Sierran frontal fault system when analyzed with data from previous studies to the south. Several locations show domains of clockwise vertical-axis rotation up to 50 adjacent to regions of low or no rotation; indicating that simplistic block models of vertical-axis rotation accommodating dextral shear may require re-evaluation. Earthquake focal mechanism inversions have shown that strain near Bridgeport, CA is characterized by nearly pure normal faulting. As dip-slip faulting is not favorable to vertical-axis rotation, this suggests a change in style of strain accommodation since the time of Stanislaus Group emplacement. Ongoing work will refine tectonic domain boundaries within the research area to produce a kinematic model that includes changes in strain accommodation style and rates of vertical-axis rotation.

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

    PubMed

    Garcia, Claudia Moreira; Danni-Oliveira, Ins 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 Paran between 1989 and 2001. The data were obtained from the Environmental Health Department of Paran. 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

  4. 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

  5. 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.

  6. Synthesis and insecticidal activity of new oxime derivatives of podophyllotoxin-based phenazines against Mythimna separata Walker.

    PubMed

    Zhi, Xiaoyan; Yang, Chun; Yu, Xiang; Xu, Hui

    2014-12-15

    To discover new natural-product-based insecticidal agents, a series of novel oxime derivatives of podophyllotoxin-based phenazines modified in the C, D and E rings of podophyllotoxin were prepared and tested as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1 mg/mL. The steric configuration of IIIc was unambiguously confirmed by single-crystal X-ray diffraction analysis. Compounds IIIa-d, and IIIi exhibited an equal or higher insecticidal activity than toosendanin. PMID:25467160

  7. On the initial value problem for the wave equation in FriedmannRobertsonWalker spacetimes

    PubMed Central

    Abbasi, Bilal; Craig, Walter

    2014-01-01

    The propagator W(t0,t1)(g,h) for the wave equation in a given spacetime 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 FriedmannRobertsonWalker spacetimes 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 FriedmannRobertsonWalker 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 spacetimes. 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 spacetime (the usual Huygens principle of finite propagation speed is satisfied, of course). Third, we show that for 00 emanating from the spacetime singularity at t=0. Under reflection t??t, the FriedmannRobertsonWalker metric gives a spacetime 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 FriedmannRobertsonWalker spacetimes which exist for all ??

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

    PubMed

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

    2016-01-01

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

  9. Neuropsychological Function in a Case of Dandy-Walker Variant in a 68-Year-Old Veteran.

    PubMed

    Gross, Patricia L; Kays, Jill L; Shura, Robert D

    2016-01-01

    Dandy-Walker syndrome (DWS) is a congenital brain malformation that is characterized by partial or complete agenesis of the cerebellar vermis and cystic dilatation of the 4th ventricle that shifts ventrolaterally to displace the cerebellar hemispheres. This case is a 68-year-old male veteran with complaints of new-onset cognitive disorder who was found to have previously unsuspected DWS on head computed tomography. This is one of the first case studies to present complete neuropsychological test results in a veteran with DWS. Despite the level of abnormality on imaging, the veteran functioned well until onset of mild cognitive impairments in late adulthood. PMID:25997155

  10. Quantum mechanics of conformally and minimally coupled Friedmann-Robertson-Walker cosmology

    NASA Astrophysics Data System (ADS)

    Kim, Sang Pyo

    1992-10-01

    The expansion method by a time-dependent basis of the eigenfunctions for the space-coordinate-dependent sub-Hamiltonian is one of the most natural frameworks for quantum systems, relativistic as well as nonrelativistic. The complete set of wave functions is found in the product integral formulation, whose constants of integration are fixed by Cauchy initial data. The wave functions for the Friedmann-Robertson-Walker (FRW) cosmology conformally and minimally coupled to a scalar field with a power-law potential or a polynomial potential are expanded in terms of the eigenfunctions of the scalar field sub-Hamiltonian part. The resultant gravitational field part which is an ``intrinsic'' timelike variable-dependent matrix-valued differential equation is solved again in the product integral formulation. There are classically allowed regions for the ``intrinsic'' timelike variable depending on the scalar field quantum numbers and these regions increase accordingly as the quantum numbers increase. For a fixed large three-geometry the wave functions corresponding to the low excited (small quantum number) states of the scalar field are exponentially damped or diverging and the wave functions corresponding to the high excited (large quantum number) states are still oscillatory but become eventually exponential as the three-geometry becomes larger. Furthermore, a proposal is advanced that the wave functions exponentially damped for a large three-geometry may be interpreted as ``tunneling out'' wave functions into, and the wave functions exponentially diverging as ``tunneling in'' from, different universes with the same or different topologies, the former being interpreted as the recently proposed Hawking-Page wormhole wave functions. It is observed that there are complex as well as Euclidean actions depending on the quantum numbers of the scalar field part outside the classically allowed region both of the gravitational and scalar fields, suggesting the usefulness of complex geometry and complex trajectories. From the most general wave functions for the FRW cosmology conformally coupled to scalar field, the boundary conditions for the wormhole wave functions are modified so that the modulus of wave functions, instead of the wave functions themselves, should be exponentially damped for a large three-geometry and be regular up to some negative power of the three-geometry as the three-geometry collapses. The wave functions for the FRW cosmology minimally coupled to an inhomogeneous scalar field are similarly found in the product integral formulation. The role of a large number of the inhomogeneous modes of the scalar field is not only to increase the classically allowed regions for the gravitational part but also to provide a mechanism of the decoherence of quantum interferences between the different sizes of the universe.

  11. 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

  12. 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.

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

    PubMed

    Patnaik, Lalit; Umanand, Loganathan

    2015-12-01

    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

  14. Buses, cars, bicycles and walkers: the influence of the type of human transport on the flight responses of waterbirds.

    PubMed

    McLeod, Emily M; Guay, Patrick-Jean; Taysom, Alice J; Robinson, Randall W; Weston, Michael A

    2013-01-01

    One way to manage disturbance to waterbirds in natural areas where humans require access is to promote the occurrence of stimuli for which birds tolerate closer approaches, and so cause fewer responses. We conducted 730 experimental approaches to 39 species of waterbird, using five stimulus types (single walker, three walkers, bicycle, car and bus) selected to mimic different human management options available for a controlled access, Ramsar-listed wetland. Across species, where differences existed (56% of 25 cases), motor vehicles always evoked shorter flight-initiation distances (FID) than humans on foot. The influence of stimulus type on FID varied across four species for which enough data were available for complete cross-stimulus analysis. All four varied FID in relation to stimuli, differing in 4 to 7 of 10 possible comparisons. Where differences occurred, the effect size was generally modest, suggesting that managing stimulus type (e.g. by requiring people to use vehicles) may have species-specific, modest benefits, at least for the waterbirds we studied. However, different stimulus types have different capacities to reduce the frequency of disturbance (i.e. by carrying more people) and vary in their capacity to travel around important habitat. PMID:24367498

  15. Fostering locomotor behavior of children with developmental disabilities: An overview of studies using treadmills and walkers with microswitches.

    PubMed

    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). Twenty-one of the studies involved the use of treadmills (i.e., 13 were aimed at children with cerebral palsy, 6 at children with Down syndrome, and 2 at children with Rett syndome or cerebellar ataxia). The remaining five studies concerned the use of walkers with microswitches and contingent stimulation with children with multiple disabilities. The outcomes of the studies tended to be positive but occasional failures also occurred. The outcomes were analyzed considering the characteristics of the approaches employed, the implications of the approaches for the participants' overall functioning situation (development), as well as methodological and practical aspects related to those approaches. Issues for future research were also examined. PMID:18573637

  16. Redescription of Argizala brasiliensis Walker, 1869 (Orthoptera: Grylloidea: Trigonidiidae: Nemobiinae: Pteronemobiini) and consideration of its morphological proximity to other Pteronemobiini Nearctic genera.

    PubMed

    Pereira, Marcelo Ribeiro; Martins, Luciano De P; Fernandes, Maria Luiza; Zefa, Edison; Sperber, Carlos Frankl

    2015-01-01

    Although male crickets provide more informative characters for the delimitation of species and genera, many taxonomic descriptions are based only on females. This is the case for Argizala Walker, 1869 and its two valid species, A. brasiliensis Walker, 1869 and A. hebardi Rehn, 1915. We provide herein a redescription of A. brasiliensis based on a male collected in the Pampa Biome, Capo do Leo municipality, Rio Grande do Sul State, Brazil. We present photographs of epitype and male genitalia, and discuss the diagnostic features of the genus and its morphological proximity to other Pteronemobiini Nearctic genera. PMID:26249883

  17. Seasonal Nutrient Dynamics of Foliage and Litterfall on Walker Branch Watershed, a Deciduous Forest Ecosystem

    SciTech Connect

    Grizzard, T. Henderson, G.S. Clebsch, E.

    1999-01-01

    A detailed twelve-month study of litterfall, live foliage biomass, and seasonal nutrient (nitrogen, phosphorus, potassium, calcium, sodium, and magnesium) dynamics in tree components was performed for forest types on Walker Branch Watershed, Oak Ridge, Tennessee. Biomass and nutrient content of foliage, reproductive parts and branches were examined for ten dominant trees in order to assess the relative importance of litterfall in returning nutrients to the forest floor in four different forest types. Litterfall, measured in pine, pine-oak-hickory, oak-hickory, and mesophytic hardwood forests, was separated into three components (leaves, reproductive parts, and branches). Seasonal comparisons of those forest types were made for biomass and nutrient inputs for each component and for total litterfall. Each forest types was characterized by total annual input to the forest floor of biomass and individual nutrients for each component as well as total litterfall. Canonical analysis was performed on the yearly totals to test for significant differences among the forest types. Live foliage from the ten predominant species of trees on the watershed, determined by order of total basal area, was analyzed for biomass, nutrient concentration, and changes in nutrient content through the growth season. Seasonal trends for these variables, including the ranking of nutrient concentrations for spring versus fall, were discussed in relation to differential growth, translocation, and leaching factors. Most of the litterfall in all forest types (77-85%) was in leaves with fall maximum. Reproductive parts (8-14% with spring and fall maxima) and branches (8-11% with no seasonal trend) contributed the remainder. The ranking of nutrient content in litterfall was similar in spring and fall, except for the replacement of nitrogen by calcium in autumn as the predominant nutrient (followed by K > Mg > P > Na). Comparisons were made between weight and nutrient content for living leaves and leaf litter input in litterfall. The ranking of total nutrient content per leaf in spring foliage was N > K > Ca > Mg > P > Na. The autumn foliage ranking was the same as that for autumn leaf litterfall (Ca > N > K > Mg > P > Na), the change being due to differing behavior of the particular nutrients (translocation, biomass dilution and removal by leaching). In the four forest types analyzed, significant differences occurred in the biomass and individual nutrients recycled to the forest floor. The greatest litterfall and amounts of nitrogen input occurred in the pine forest type. Oak-hickory forests had the greatest litter inputs of magnesium and potassium. Calcium return was greatest in the mesophytic hardwood forest. No marked differences in the amounts of sodium and phosphorus return in the forest floor occurred among mesophytic hardwoods and oak-hickory forest types, which were consistently higher than pine and pine-oak-hickory forest values.

  18. Active tectonics of the northwestern tip of Walker Lane in southern Oregon

    NASA Astrophysics Data System (ADS)

    Waldien, T.

    2012-12-01

    We use newly-acquired LiDAR topographic data to characterize the active tectonics of the Klamath Basin in southern Oregon. Three key tectonic domains present on the western edge of the North American plate, the Walker Lane Fault Zone (WLFZ), the northwestern Basin and Range extensional province (NWBR), and the Cascade arc, intersect in the region of the Klamath Basin. Right-oblique shear across the WLFZ accommodates ~15-30% of motion between the North America and Pacific plates in eastern California and western Nevada. Geologic data indicate that the WLFZ has been growing to the northwest since its inception after ~13 Ma. The northwestern tip of the WLFZ extends northwest through eastern California into southern Oregon where it intersects the Klamath Basin and Cascade arc. The Klamath Basin is a graben and marks the western-most extent of the Basin and Range extensional province at the latitude of the California-Oregon border. Due to the intersection between the WLFZ, the western margin of Basin and Range, and the Cascade arc, it is unclear whether the Klamath Basin opened in response to northwest propagation of the WLFZ or whether the WLFZ overprints a pre-existing arc-related graben on the edge of the Basin and Range. Faults in the Klamath Basin region fall into two groups. Group 1 faults bound the Klamath Graben, are north striking, and are marked by topographic escarpments with more than 600m local relief. Quaternary alluvial deposits bury the fault traces. Fault scarps mark the traces of Group 2 faults. Group 2 faults occur within the basin and include segments that strike north and northwest, creating a complex stair-step map pattern. A systematic overprinting of relatively more eastern faults by faults to the west characterizes the Group 2 faults. Moreover, Group 2 faults cut tilt blocks associated with Group 1 faults. Topographic relief across Group 2 faults is less than ~350m. Fault scarps in unconsolidated alluvium have as much as ~2 m of vertical and ~40 m of strike slip separation. Right-oblique slip active faulting in the graben center either (A) overprints tilt blocks formed due to earlier Basin and Range extension or (B) opened the Klamath Basin and is now localized along the basin axis. Regardless, these new data reveal a previously unrecognized seismic hazard. An earthquake sequence in 1993, the Klamath Falls earthquakes, consisted of two M6 events, neither of which ruptured to the surface. The longest continuous group 2 fault, which has a ~320m vertical separation, is ~25 km long. Earthquake scaling relationships and the length and size of the scarp on this fault indicate that at least one M7 event has occurred in the Klamath Falls area, larger than any historic earthquake.

  19. Relationships of pinon juniper woodland expansion and climate trends in the Walker Basin, Nevada

    NASA Astrophysics Data System (ADS)

    Donald, Jonathon

    Landscapes are in constant flux. Vegetation distributions have changed in conjunction with climate, driven by factors such as Milankovitch cycles and atmospheric composition. Until recently, these changes have occurred gradually. Human populations are altering Earth's systems, including atmospheric composition and land use. This is altering vegetation distributions at landscape scales due to changes in species potential niche, as well as current and historical alteration of their realized niche. Vegetation shifts have the potential to be more pronounced in arid and mountainous environments as resources available to plants such as soil moisture are more limiting. In the Great Basin physiographic region of the western United States, woody encroachment of pinon juniper (Pinus monophylla & Juniperus osteosperma) woodlands is well known, but the drivers of its expansion are not well understood across elevational gradients. Predominant theories of future vegetation distribution change due to a changing climate, predict that montane species will move upslope in response to increasing temperatures. In pinon juniper woodlands, the focus has been on downslope movement of woodlands into other ecosystem types. The drivers for this are typically thought to be historical land uses such as grazing and fire exclusion. However, infilling and establishment is occurring throughout its distribution and relatively little attention has been paid to woodland movement uphill. This study focuses on two mountain ranges within the Walker Lake Basin, so as to understand changes occurring along the full gradient of pinon juniper woodlands, from lower to upper treeline, on both the western and eastern side of the ranges. The overall goal of this study was to understand trends of change (increasing, decreasing canopy density) in pinon juniper woodlands and determine if these trends were related to climate change trends. Trends in both vegetation and climate were analyzed for the entire distribution of pinon juniper within the study area, and aggregated by ecologically pertinent zones of woodlands. Climate is highly variable and difficult to accurately represent at fine spatial scales, so aggregation to pertinent zones such as lower ecotones, upper ecotones, and main distribution of woodlands, allowed for meaningful inferences of how the amount of change among climatic variables over time were related to densification of pinon juniper canopy. The Mann-Kendall test of trend is able to detect trends in time series stacks of spectral vegetation indexes and discern between both large and small magnitude trends. Within the study area, pinon juniper woodlands showed the greatest increases in canopy density at upper ecotones, followed by lower ecotones. The amount of change corresponds to an increase of about 25% in canopy density over the 30 year time period in the upper ecotones, and about 18% increase at lower ecotones. Larger change at the upper ecotone suggests that pinon juniper is responding to climatic change in line with theories of vegetation response to climate. This is best explained by small increases in winter precipitation and larger increases in minimum temperature. These conditions would favor increased canopy by promoting seedling establishment. Weaker correlations with changes in climatic variables at the lower ecotone suggest that other factors, especially historic land use effects, are likely influencing pinon juniper to a greater degree. This follows others findings concerning encroachment, but suggests that the amount of change among climatic variables directly relates to overall rates of establishment and increasing canopy density. Encroachment at the lower bound of pinon juniper distribution is likely a response to artificial reduction of the realized niche.

  20. Magmatic-Tectonic Interactions: Implications for Seismic Hazard Assessment in the Central Walker Lane and Long Valley Caldera Regions

    NASA Astrophysics Data System (ADS)

    Chacko, R.; Hammond, W. C.; Blewitt, G.; Bormann, J. M.

    2014-12-01

    Accurate estimates of fault slip rates based on geodetic data rely on measurements that represent the long-term deformation of the crust. In the Central Walker Lane/Sierra Nevada transition, the Long Valley Caldera region has experienced multiple episodes of uplift and subsidence during the last four decades. The latest episode began in late 2011 and is detectable as a transient signal in the time series of GPS stations around the caldera. These transient signals become more apparent and reveal the extent of the impact on the ambient crustal deformation field of the Walker Lane when the velocity vectors are transformed to a Sierra-Nevada reference frame. Estimating contemporary slip-rates on faults for the purpose of seismic hazard assessment in the region around Long Valley requires detecting and subtracting the transient signals caused by the uplift and subsidence in the caldera. We estimate the geographic extent to which the ambient crustal deformation field is significantly perturbed by ongoing magmatic activity in Long Valley. We present a time variable 3D deformation field constrained by InSAR and GPS observations, and discuss the implications that tectonic-magmatic interaction have for estimates of present-day fault slip-rate. We model the time dependent deformation at Long Valley by analyzing InSAR time series from Envisat and ERS interferograms spanning a period of more than 19 years. We use an analytical volcano deformation source model derived from vertical (GPS) and line of site (InSAR) component of geodetic observations to estimate the horizontal component of the signals associated with magmatic activity beneath the caldera. Previous studies showed that the latest episode of uplift can be modeled with a Mogi source located at a depth of ~6 km with a volume change of 0.03 km3 beneath the resurgent dome. This model predicts a perturbation to the ambient crustal deformation field extending as far as 60 km from the center of the resurgent dome. Thus the area affected by Long Valley extends from north of Mono Lake southward to Owens Lake, and eastward to the Mina deflection of the Walker Lane, potentially influencing the estimated slip rates for a dozen or more major faults.

  1. Interpretation of simple and cloud-resolving simulations of moist convection radiation interaction with a mock-Walker circulation

    NASA Astrophysics Data System (ADS)

    Bretherton, Christopher S.; Blossey, Peter N.; Peters, Matthew E.

    2006-11-01

    An idealized two-dimensional mock-Walker circulation in the tropical atmosphere forced by prescribed horizontal gradients in sea-surface temperature (SST) is discussed. This model problem includes feedbacks between cumulus convection and tropical large-scale circulations that have proved challenging for global climate models to predict accurately. Three-dimensional cloud-resolving model (CRM) simulations that explicitly simulate turbulent circulations within individual cloud systems across 4,096 and 1,024 km-wide Walker circulations are compared with a simple theoretical model, the Simplified Quasiequilibrium Tropical Circulation Model (SQTCM). This theoretical model combines the weak-temperature-gradient approximation with a unimodal truncation of tropospheric vertical structure coupled to highly simplified formulations of moist precipitating cumulus convection and its cloud-radiative feedbacks. The rainfall, cloud and humidity distribution, circulation strength, energy fluxes and scaling properties are compared between the models. The CRM-simulated horizontal distribution of rainfall and energy fluxes are adequately predicted by the SQTCM. However, the humidity distribution (drier subsidence regions and high-humidity boundary layers in the CRM), vertical structure and domain-size scaling of the circulation differ significantly between the models. For the SQTCM, the concept of gross moist stability related to advection of moist static energy (MSE) out of tropospheric columns by the mean divergent circulation is used to explain the width and intensity of the rainy region. Column MSE budgets averaged across the ascent branch of the simulated Walker circulation provide similar insight into the cloud-resolving simulations after consideration of the more complex horizontal and vertical circulation structure and the role of transient eddies. A nondimensional ascent-region moist stability ratio ?, analogous to the SQTCM gross moist stability, is developed. One term of ? is related to the vertical profiles of ascent-region mean vertical motion and ascent-region edge MSE; a second term is proportional to eddy export from the ascent region. Smaller ? induces a narrower, rainier ascent region. The sensitivity of the SQTCM and CRM to a uniform 2 K increase in SST is compared, and the rainy upward branch of the circulation narrows in both models. MSE budget arguments are used to explain this behavior. In the simple model, the gross moist stability is a decreasing function of tropospheric temperature. Hence gross moist stability reduces and the ascent region narrows as the SST increases. In the CRM, increased atmospheric radiative cooling due to the warmer and moister troposphere destabilizes the MSE profile and decreases ?, inducing a narrower ascent region. In the CRM, and to a lesser extent in the SQTCM, intensified shortwave cloud forcing in the warmer climate causes a negative radiative feedback on the SST change.

  2. Walker 256/B malignant breast cancer cells improve femur angioarchitecture and disrupt hematological parameters in a rat model of tumor osteolysis.

    PubMed

    Badraoui, Riadh; Boubakri, Mariem; Bedbabiss, Maissa; Ben-Nasr, Hmed; Rebai, Tarek

    2014-04-01

    This study was designed to assess femur angioarchitecture and hematological effects of Walker 256/B cells in a rat model of tumor osteolysis. Tumor osteolysis was induced by in situ inoculation of Walker 256/B malignant cells. Six other rats were sham operated and served as control. Twenty days later, rats were euthanized, and femurs were collected than radiographed. Angioarchitecture [mean lumen diameter (MLD), wall thickness (WTh), Vessel number, volume, and separation (VNb, VV, and VSp respectively)] was studied by histomorphometry at 2 different positions (P1: diaphysis, and P2: metaphysis) of the operated femora. Some hematological parameters were also assessed. Walker 256/B induced marked tumor osteolysis, with cortical perforation and trabecular destruction, associated increase in bone vascularization (increases of VNb and VV and decrease of VSp). Angioarchitecture of W256/B rats was disorganized and showed large MLD and lower WTh. These effects were more prominent in P2. When compared to Sham group, significantly decreases at levels of red blood cell (RBC), hemoglobin (Hb), hematocrit (Ht), and white blood cell (WBC) were observed in W256/B rats. These results suggest that Walker 256/B cells induced tumor osteolysis, improve hypervasculature especially near the tumoral foci (P2) associated hematological disruption. Besides, tumor vessels showed abnormal (enlarged and thinner) and disorganized morphology. PMID:24318993

  3. 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 ...

  4. Postharvest treatment of fresh fruit from California with methyl bromide for postharvest control of light brown apple moth, Epiphyas postvittana (Walker)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl bromide chamber fumigations were evaluated for postharvest control of light brown apple moth (LBAM), Epiphyas postvittana (Walker), in fresh fruit exports. To simulate external feeding, larvae were contained in gas-permeable cages and distributed throughout loads of peaches, plums, nectarines...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. 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...

  8. 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

    Lszl, Gyula M; Ronkay, Gbor; Ronkay, Lszl

    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

  9. 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...

  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. Plant-growth response to various combinations of mulches and spoil substrates on a Walker County, Alabama, surface coal mine

    SciTech Connect

    Cross, E.A.; Gabrielson, F.C.; Hughes, T.H.

    1982-05-01

    In 1978-1979, Walker County, Alabama, was the site of an experiment designed to assess plant growth and soil erosion. The experiment utilized 6 mulch treatments applied to each of 3 coal surface mine substrates. The mulches (wood fiber, hardwood bark, pine bark, waste compost, paper-slag, and no mulch application) were randomly combined with either A + B horizon soil, shale, or a mixture of the two. The resulting 18 plots were replicated on two slopes (N-S). A standard seed-fertilizer regimen was applied to all plots. Plots were read in June and October 1979 for species composition, density, and plane cover. Overall grass growth, as measured by plane cover, was best on mixed substrate, and growth was not significantly different between shale and topsoil plots. Density and cover provided by volunteer species varied according to slope, substrate, and mulch combinations. Overall, numbers of spoil arthropods did not show great differences according to slope or substrate.

  12. Evaluation of geodetic and geologic datasets in the Northern Walker Lane-Summary and recommendations of the Workshop

    USGS Publications Warehouse

    Briggs, Richard W.; Hammond, William C.

    2010-01-01

    The Northern Walker Lane comprises a complex network of active faults in northwestern Nevada and northeastern California bound on the west by the Sierra Nevada and on the east by the extensional Basin and Range Province. Because deformation is distributed across sets of discontinuous faults, it is particularly challenging to integrate geologic and geodetic data in the NWL to assess the region's seismic hazard. Recent GPS measurements show that roughly one centimeter per year of relative displacement is accumulating across a zone about 100 km wide at the latitude of Reno, Nevada, but it is not clear where or how much of this strain might ultimately be released in damaging earthquakes. Despite decades of work in the region, the sum of documented late Pleistocene to recent slip rates is distinctly less than the GPS-measured relative displacement.

  13. Hydrologic model based on deep test data from the Walker O No. 1 well, Terminal Geyser, California

    SciTech Connect

    Beall, J.J.

    1981-10-01

    The Shasta Forest No. 1 Well (renamed Walker O No. 1) at Terminal Geyser, California, was reentered and deepened from 1258 to 4008 feet. Temperature logs indicate the well penetrated a laterally flowing thermal aquifer between 1400 and 2200 feet. Large amounts of drilling fluids were lost in that zone. Maximum temperature in the well (10 months after drilling) was 348/sup 0/F at 2000 feet. A large reversed temperature gradient zone occurs below 2400 feet. Bottom hole temperature is 256/sup 0/F. After completion, the well was flowed for about five hours with nitrogen injection at 2000 feet. Samples taken throughout the flow indicate that fluids lost during drilling were not completely recovered. Salinity increased steadily during the flow period. Ratios of Na, K, and Ca were nearly constant, however, and application of Na-K and Na-K-Ca geothermometers indicate these fluids were in equilibrium with rocks at a temperature of 448-449/sup 0/F.

  14. 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.

  15. InSAR analysis of the 2008 Reno-Mogul earthquake swarm: Evidence for incipient westward migration of Walker Lane style dextral faulting

    NASA Astrophysics Data System (ADS)

    Bell, J. W.; Amelung, F.; Henry, C. D.

    2011-12-01

    Analysis and modeling of InSAR data from small magnitude earthquakes can provide insights into the long-term evolution of the Basin and Range and Walker Lane. InSAR data covering the 2008 Reno-Mogul M 4.7 earthquake swarm indicate that the swarm was produced by slip on a newly recognized, northwest-striking dextral fault in the Reno basin. The earthquake is the smallest magnitude event modeled with InSAR to date in the seismically active western Basin and Range, and it provides new insights into regional neotectonic relations. The Reno basin is dominated by post-mid-Miocene, east-west extension near the boundary with the relatively stable Sierra Nevada and west of the northern Walker Lane, and the 2008 swarm occurred on the northern end of the Carson Range, a north-plunging extensional anticline. Although no surface rupture was associated with the swarm, 0.5-2.5 cm of radar line-of-sight change was detected by InSAR over a ~150 km2 area. We modeled six descending and six ascending InSAR pairs covering the swarm using the geodetic modeling program Geodmod. Inverse modeling of the InSAR data suggests that the swarm was generated by 25-75 cm of dextral displacement on a N44W-striking fault having a ~3 km rupture length and a rupture depth of ~2 km. As much as 4 cm of total across-fault dextral offset was detected. The InSAR results further indicated that a significant part of the ground deformation was post-seismic, in agreement with continuous GPS data (Blewitt et al., 2008). The model-derived moment magnitude Mw 5.3 was found to be larger than the instrumental Mw 5.1 indicating that a significant amount of the post-seismic slip was aseismic. The InSAR-detected strike-slip ground deformation is unique for the Reno basin which is in the extensional domain of the Sierra Nevada-Basin and Range Transition Zone. The modeling results support the concept that transcurrent faulting of the Walker Lane is migrating westward into areas previously affected only by extension, as suggested in earlier studies of the southern Walker Lane (e.g., Stockli et al., 2003). The modeled fault parallels major faults of the Walker Lane to the east and north that initiated in the latest Miocene or Pliocene. Superposition of the Walker Lane style faulting on the extensional Reno basin mostly reflects northward propagation and westward encroachment of the youngest part of the Walker Lane system.

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

    PubMed

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

    2015-01-01

    Four fruit fly genera, Ichneumonosoma de Meijere, Pelmatops Enderlein, Pseudopelmatops Shiraki and Soita Walker, were studied and 19 species are recognized. Three new species, Soita infuscata Chen & Norrbom, Ichneumonosoma quadripunctata Chen & Freidberg, and I. triangularis Chen & Norrbom are described and illustrated. Ichneumonosoma and Soita are revised, and keys to all the species are provided. Ichneumonosoma imitans (de Meijere) is newly recorded from Thailand. One new synonym is established: Soita Walker = Xaniosternum Enderlein, and Xaniosternum ophioneum Enderlein is moved from Xaniosternum to Soita (n. comb.). In addition, new morphological, geographic and biological information for two stalk-eyed fruit fly genera, Pelmatops and Pseudopelmatops, are provided. Pelmatops fukienensis Zia & Chen is newly recorded from Burma, Pelmetops ichneumoneus (Westwood) is newly recorded from Thailand and Burma, Pseudopelmatops angustifasciatus Zia & Chen is newly recorded from Vietnam, and the male of P. angustifasciatus is described and illustrated for the first time. The morphology of the compound eye and occipital protuberance of Pelmatops and Pseudopelmatops is described and illustrated for the first time. A cladistic analysis based on morphological characters of adults, a partial molecular analysis using the nuclear 28S rDNA (28S) and the mitochondrial cytochrome c oxidase I (COI) genes and a combined dataset were conducted to reconstruct the phylogeny of the four genera and their species. The results showed good support for monophyly of each of the four genera and the clade of the stalk-eyed fruit flies (Pelmatops + Pseudopelmatops). However, relationships of the stalk-eyed fruit flies with Soita and Ichneumonosoma are not clearly resolved, with the morphological analysis indicating that Ichneumonosoma is the sister group of the stalk-eyed fruit flies, but the 28S analysis and the combined analysis group Soita closer to the stalk-eyed fruit flies. Regarding relationships amongst congeners, Pelmatops was well resolved; Ichneumonosoma and Soita were partly resolved, and Pseudopelmatops was unresolved. In addition, a hypothesis about the biology of Pseudopelmatops and its relationship with Sesiidae (Lepidoptera) is discussed. PMID:26623901

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

    PubMed

    Khuong, Anas; Lecheval, Valentin; Fournier, Richard; Blanco, Stphane; Weitz, Sbastian; 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 0.50.5 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

  18. 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.

  19. How Do Ants Make Sense of Gravity? A Boltzmann Walker Analysis of Lasius niger Trajectories on Various Inclines

    PubMed Central

    Khuong, Anas; Lecheval, Valentin; Fournier, Richard; Blanco, Stphane; Weitz, Sbastian; 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 0.50.5 m plane canvas, which was tilted with 5 various inclinations by rad ( data points). At the population scale, support inclination favors dispersal along uphill and downhill directions. An ant's decision making process is modeled using a version of the Boltzmann Walker model, which describes an ant's random walk as a series of straight segments separated by reorientation events, and was extended to take directional influence into account. From the data segmented accordingly ( segments), this extension allows us to test separately how average speed, segments lengths and reorientation decisions are affected by support inclination and current walking direction of the ant. We found that support inclination had a major effect on average speed, which appeared approximately three times slower on the incline. However, we found no effect of the walking direction on speed. Contrastingly, we found that ants tend to walk longer in the same direction when they move uphill or downhill, and also that they preferentially adopt new uphill or downhill headings at turning points. We conclude that ants continuously adapt their decision making about where to go, and how long to persist in the same direction, depending on how they are aligned with the line of maximum declivity gradient. Hence, their behavioral decision process appears to combine klinokinesis with geomenotaxis. The extended Boltzmann Walker model parameterized by these effects gives a fair account of the directional dispersal of ants on inclines. PMID:24204636

  20. Optimal handgrip height of four-wheeled walker on various road conditions to reduce muscular load for elderly users with steady walking.

    PubMed

    Takanokura, Masato

    2010-03-22

    A four-wheeled walker is a valuable tool for assisting elderly persons with walking. The handgrip height is one of the most important factor determining the usefulness of the walker. However, the optimal handgrip height for elderly users has not been considered from a biomechanical viewpoint. In this study, the handgrip height was optimized by a two-dimensional mechanical model to reduce muscular loads in the lower body as well as in the upper body with various road conditions during steady walking. A critical height of the handgrip existed at 48% of the body height for the user regardless of gender and body dimension. A lower handgrip relieved muscular load for stooping users with a lower standing height. The stooping user pushed the handgrip strongly in the perpendicular direction by leaning the upper body on the walker. However, upright users with a higher standing height should use a four-wheeled walker with a higher handgrip for maintaining his or her upright posture. For downhill movement, the optimal handgrip height depended on the slope angle and the friction coefficient between the road and the wheels of the walker. On a low-friction downhill such as asphalt with a steeper slope angle, the user was required to maintain an erect trunk with a higher handgrip and to press on the handgrip strongly in the perpendicular direction. Movement on a low-friction road was easier for users on a flat road and an uphill road, but it compelled distinct effort from users when moving downhill. PMID:20006337

  1. The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

    NASA Astrophysics Data System (ADS)

    Kell, Anna Marie

    The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery documents the timing of strain transfer from the Imperial fault onto the San Andreas fault through the application of sequence stratigraphy. Evidence shows that the formation of the Salton and Mesquite sub-basins and the associated change of strain partitioning occurred within the last 20-40 k.y., essentially modifying a broader zone of transtension bounding the Imperial and San Andreas faults into two smaller zones of focused extension. The north-central Walker Lane contains a diffuse network of both strike-slip and normal faults, with some degree of strain partitioning characterized by normal faulting to the west along the eastern edge of the Sierra Nevada mountain range, and strike-slip faults to the east that define a diffuse boundary against the Basin and Range proper. A seismic study across the Mount Rose fault zone, bounding the Carson Range near Reno, Nevada, was carried out to investigate slip across a potential low-angle normal fault. A hammer seismic reflection and refraction profile combined with airborne LiDAR (light detection and ranging) imagery highlights fault scarp modification through minor slumping/landslides, providing a better understanding of the nature of slip on this fault. The northeastern margin of the Walker Lane is a region where both "Basin and Range" style normal faults and dextral strike-slip faults contribute to the northward propagation of the Walker Lane (essentially parallel to an equivalent northward propagation of the Mendocino triple junction). Near this intersection lies Pyramid Lake, bounded to the southwest by the dextral Pyramid Lake fault and to the northeast by the normal Lake Range fault. A high-resolution (sub-meter) seismic CHIRP survey collected in 2010 shows intriguing relationships into fault architecture beneath Pyramid Lake. Over 500 line-km of seismic data reveal a polarity flip in basin structure as down-to-the-east motion at the northern end of the Pyramid Lake fault rapidly gives way to down-to-the-west normal motion along the Lake Range fault. Alternating patterns of asymmetric and symmetric stratal patterns west of the Lake Range fault provides some evidence for segmentation of total slip along this large normal fault. Using dated sediment cores, slip rate for the Lake Range fault was found to be approximately 1 mm/yr during the Holocene. A complex zone of transtenstion was also observed in seismic CHIRP data in the northwest quadrant of the lake, where short, discontinuous faults hint at the development of a nascent shear zone trending to the northwest. (Abstract shortened by UMI.)

  2. 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 magnitudes of total slip across different parts. Despite the progressive migration of the MTJ, arc magmatism ceased abruptly at the latitude of Lake Tahoe (39.2) at about 3 Ma, and the southern end of the active Cascade arc jumped ~160 km northward to Lassen Peak (40.5), where it remains. Geologic data indicate strike-slip faulting began between these two areas immediately following the end of arc magmatism. The southern Cascade arc is undergoing ~east-west extension, which was the case for the northern Walker Lane immediately before strike-slip faulting began. Further progression or steps in magmatism and strike-slip faulting will likely follow further northward migration of the MTJ.

  3. Studying methane migration mechanisms at Walker Ridge, Gulf of Mexico, via 3D methane hydrate reservoir modeling

    SciTech Connect

    Nole, Michael; Daigle, Hugh; Mohanty, Kishore; Cook, Ann; Hillman, Jess

    2015-12-15

    We have developed a 3D methane hydrate reservoir simulator to model marine methane hydrate systems. Our simulator couples highly nonlinear heat and mass transport equations and includes heterogeneous sedimentation, in-situ microbial methanogenesis, the influence of pore size contrast on solubility gradients, and the impact of salt exclusion from the hydrate phase on dissolved methane equilibrium in pore water. Using environmental parameters from Walker Ridge in the Gulf of Mexico, we first simulate hydrate formation in and around a thin, dipping, planar sand stratum surrounded by clay lithology as it is buried to 295mbsf. We find that with sufficient methane being supplied by organic methanogenesis in the clays, a 200x pore size contrast between clays and sands allows for a strong enough concentration gradient to significantly drop the concentration of methane hydrate in clays immediately surrounding a thin sand layer, a phenomenon that is observed in well log data. Building upon previous work, our simulations account for the increase in sand-clay solubility contrast with depth from about 1.6% near the top of the sediment column to 8.6% at depth, which leads to a progressive strengthening of the diffusive flux of methane with time. By including an exponentially decaying organic methanogenesis input to the clay lithology with depth, we see a decrease in the aqueous methane supplied to the clays surrounding the sand layer with time, which works to further enhance the contrast in hydrate saturation between the sand and surrounding clays. Significant diffusive methane transport is observed in a clay interval of about 11m above the sand layer and about 4m below it, which matches well log observations. The clay-sand pore size contrast alone is not enough to completely eliminate hydrate (as observed in logs), because the diffusive flux of aqueous methane due to a contrast in pore size occurs slower than the rate at which methane is supplied via organic methanogenesis. Therefore, it is likely that additional mechanisms are at play, notably bound water activity reduction in clays. Three-dimensionality allows for inclusion of lithologic heterogeneities, which focus fluid flow and subsequently allow for heterogeneity in the methane migration mechanisms that dominate in marine sediments at a local scale. Incorporating recently acquired 3D seismic data from Walker Ridge to inform the lithologic structure of our modeled reservoir, we show that even with deep adjective sourcing of methane along highly permeable pathways, local hydrate accumulations can be sourced either by diffusive or advective methane flux; advectively-sourced hydrates accumulate evenly in highly permeable strata, while diffusively-sourced hydrates are characterized by thin strata-bound intervals with high clay-sand pore size contrasts.

  4. 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.

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

    PubMed

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

    2008-12-01

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

  6. A dynamic correspondence between Bose-Einstein condensates and Friedmann-Lemaitre-Robertson-Walker and Bianchi I cosmology with a cosmological constant

    SciTech Connect

    D'Ambroise, Jennie; Williams, Floyd L.

    2010-06-15

    In some interesting work of James Lidsey, the dynamics of Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology with positive curvature and a perfect fluid matter source is shown to be modeled in terms of a time-dependent, harmonically trapped Bose-Einstein condensate. In the present work, we extend this dynamic correspondence to both FLRW and Bianchi I cosmologies in arbitrary dimension, especially when a cosmological constant is present.

  7. Minimum of PDOP and its applications in inter-satellite links (ISL) establishment of Walker-δ constellation

    NASA Astrophysics Data System (ADS)

    Han, Songhui; Gui, Qingming; Li, Guozhong; Du, Yuanlu

    2014-08-01

    Within the next decade, there will be a number of GNSS (Global Navigation Satellite System) available, i.e. modernized GPS, Galileo, restored GLONASS, BeiDou and many other regional GNSS augmentation systems. Thus, measurement redundancies and geometry of the satellites can be improved. GDOP (Geometric Dilution of Precision) and PDOP (Position Dilution of Precision) are associated with the constellation geometry of satellites, and they are the geometrically determined factors that describe the effect of geometry on the relationship between measurement error and position error. GDOP and PDOP are often used as standards for selecting good satellites to meet the desired positioning precision. In this paper, the related conclusions of minimum of GDOP which was discussed are given, and it is used to study the minimum of PDOP for two cases that the receiver is on the earth’s surface and the receiver is on satellite. The corresponding theorem and constructive solutions of minimum of PDOP are given. Then, the rationality of the ISL (inter-satellite link) establishment criteria in Walker-δ constellation is discussed by using the theory of minimum of PDOP. Finally, the minimum of PDOP is calculated when the number of satellites is 4-10, and these results are verified by using Monte Carlo method.

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

    PubMed Central

    Lv, Min; Wu, Wenjun; Liu, Huixia

    2014-01-01

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

  9. Naproxen, clenbuterol and insulin administration ameliorates cancer cachexia and reduce tumor growth in Walker 256 tumor-bearing rats.

    PubMed

    Piffar, P M; Fernandez, R; Tchaikovski, O; Hirabara, S M; Folador, A; Pinto, G J; Jakobi, S; Gobbo-Bordon, D; Rohn, T V; Fabrcio, V E B; Moretto, K D; Tosta, E; Curi, R; Fernandes, L C

    2003-11-25

    Cancer cachexia is characterized by anorexia and intense peripheral catabolism. We examine the potential benefits of combination of different anabolic agents such as insulin and clenbuterol associated to prostaglandin synthesis inhibitor (naproxen) on tumor growth, cachexia and renal function in Walker 256 tumor-bearing rats (WK). Groups were separated into WK, and WK with naproxen (WK N) or naproxen plus clenbuterol (WK NCb) or naproxen plus clenbuterol plus insulin (WK NCbI). Treatment begins at the 4th day after tumor inoculation, at the 14th day they were killed, glycemia, lacticidemia, glycogen content from liver, soleus and gastrocnemius muscles, tumor mass, body weight and kidney function were determined. Glycemia and glycogen content were reduced and lacticidemia increased in WK (p<0.05) as compared to control rats. The glycogen content recovered in all treated groups. Tumor weight was significantly reduced by the different treatments. At the 14th weight change (carcass-initial body weight) in the control increased by 38% and in the WK -2%. Naproxen treatment (WK N) induced an increased by 14%. The inclusion of clenbuterol (WK NCb) and insulin (WK NCbI) by 38 and 41%, respectively. Mean glomerular filtration rate (GFR) increased in the WK (p<0.05) as compared to control, but in the WK NCb the GFR was similar to control. Our results suggest that naproxen is able to reduce tumor growth and its association with insulin and clenbuterol induce mass weight gain and recovery energy fuel. PMID:14607327

  10. 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.

  11. Replacement by Caenis diminuta walker (ephemeroptera:caenidae) in the mayfly community structure of a thermally-stressed, southeastern stream

    SciTech Connect

    Poff, N L; Matthews, R A

    1984-01-01

    Mayfly community structure on sycamore and sweetgum leaf packs in a thermally-stressed, post-thermal and an unstressed stream were compared. Leaves were colonized over an 11 wk (77 d) period from December 1982 to March 1983. Degree-days (> 0/sup 0/C) accumulated were 1014, 638 and 627 for the thermally-stressed, post-thermal and unstressed streams, respectively. Significant differences in mayfly community structure were found between the thermally-stressed vs. the post-thermal and unstressed streams with respect to both Stenonema spp. and Caenis diminuta Walker. No significant differences in community structure were found between the two leaf species. Stenonema spp. dominated the mayfly fauna over the sampling period for both the unstressed (68%) and post-thermal (98%) streams; however, C. diminuta replaced Stenonema spp. as the dominant mayfly (88%) within leaf packs from the stream receiving thermal effluent. Additional data suggest C. diminuta is tolerant of rapidly fluctuating thermal regimes (..delta.. T of up to 11/sup 0/C in 1 h) and high temperatures (up to 40/sup 0/C). 30 references, 3 figures, 3 tables.

  12. 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.

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

    PubMed Central

    Zhang, Ai-Hua; Tan, Shi-Qiang; Zhao, Yan; Lei, Feng-Jie; Zhang, Lian-Xue

    2015-01-01

    Ginsenosides, the main effective components of Panax ginseng C.A. Meyer and Panax quinquefolius L., are important allelochemicals of ginseng. Although many studies have targeted the pharmacological, chemical, and clinical properties of ginsenosides, little is known about their ecological role in ginseng population adaptation and evolution. Pests rarely feed on ginseng, and it is not known why. This study investigated the effects of total ginsenosides on feeding behavior and activities of acetylcholinesterase (AChE) and glutathione s-transferase (GST) in Mythimna separata (Walker) larvae. The results showed that the total ginsenosides had significant antifeeding activity against M. separata larvae, determined by nonselective and selective antifeeding bioassays. In addition, the total ginsenosides had inhibitory effects on the activities of GST and AChE. The antifeeding ratio was the highest at 8?h, then decreased, and was the lowest at 16?h. Both GST and AChE activities decreased from 0?h to 48?h in all total ginsenosides treatments but increased at 72?h. Total ginsenosides had antifeeding activity against M. separata larvae and inhibitory effects on the activities of GST and AChE. PMID:26074991

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

    PubMed

    Lv, Min; Wu, Wenjun; Liu, Huixia

    2014-09-01

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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    USGS Publications Warehouse

    Williams, A. Park; Funk, Christopher C.

    2011-01-01

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55°E–140°W) since at least 1948, explaining more variance than anomalies associated with the El Niño-Southern Oscillation (ENSO). In the atmosphere, the primary mode of variability has been a corresponding trend toward greatly increased convection and precipitation over the tropical Indian Ocean. The temperature and rainfall increases in this region have produced a westward extension of the western, ascending branch of the atmospheric Walker circulation. Diabatic heating due to increased mid-tropospheric water vapor condensation elicits a westward atmospheric response that sends an easterly flow of dry air aloft toward eastern Africa. In recent decades (1980–2009), this response has suppressed convection over tropical eastern Africa, decreasing precipitation during the ‘long-rains’ season of March–June. This trend toward drought contrasts with projections of increased rainfall in eastern Africa and more ‘El Niño-like’ conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

  20. A 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.

  1. Block modeling of crustal deformation of the northern Walker Lane and Basin and Range from GPS velocities

    NASA Astrophysics Data System (ADS)

    Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corn

    2011-04-01

    We infer rates of crustal deformation in the northern Walker Lane (NWL) and western Basin and Range using data from the Mobile Array of GPS for Nevada transtension, and other continuous GPS networks including the EarthScope Plate Boundary Observatory. We present 224 new GPS velocities, correct them for the effects of viscoelastic postseismic relaxation, and use them to constrain a block model to estimate fault slip rates. The data segregate the NWL into domains based on differences in deformation rate, pattern, and style. Deformation is transtensional, with highest rates near the western and eastern edges of the NWL. Some basins, e.g., Tahoe, experience shear deformation and extension. Normal slip is distributed throughout the NWL and Basin and Range, where 11 subparallel range-bounding normal fault systems have an average horizontal extension rate of 0.1 mm/yr. Comparison between geologic and geodetic slip rates indicates that out of 12 published geologic rates, 10 agree with geodetic rates to within uncertainties. This suggests that smaller crustal blocks move steadily, similar to larger lithospheric plates, and that geodetic measurements of slip rates are reliable in zones of complex crustal deformation. For the two slip rates that disagree, geologic rates are greater. The vertical axis rotation rate of the Carson domain is -1.3 0.1/My clockwise, lower than the 3 to 6/My obtained in paleomagnetic measurements. This suggests that vertical axis rotation rates may have decreased over the last 9-13 My as the role of faulting has increased at the expense of rigid rotations.

  2. 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.

  3. Abscopal antitumor immune effects of magnet-mediated hyperthermia at a high therapeutic temperature on Walker-256 carcinosarcomas in rats.

    PubMed

    Wang, Hui; Zhang, Li; Shi, Yingrui; Javidiparsijani, Sara; Wang, Guirong; Li, Xiao; Ouyang, Weiwei; Zhou, Jumei; Zhao, Lingyun; Wang, Xiaowen; Zhang, Xiaodong; Gao, Fuping; Liu, Jingshi; Luo, Junming; Tang, Jintian

    2014-03-01

    The abscopal effect has previously been described in various tumors and is associated with radiation therapy and hyperthermia, with possible underlying mechanisms explaining each observed case. In the present study, we aimed to investigate the antitumor effects of magnet-mediated hyperthermia on Walker-256 carcinosarcomas in rats at two different temperature ranges (42-46C and 50-55C). We also aimed to identify whether a higher therapeutic temperature of magnetic-mediated hyperthermia improves the abscopal antitumor effects, where localised irradiation of the tumor causes not only the irradiated tumor to shrink, but also tumors located far from the area of irradiation. Following induction of carcinosarcoma in both sides of the body, magnet-mediated hyperthermia was applied to one side only, leaving the other side as a control. The changes in tumor growth were observed. Our results demonstrated that magnet-mediated hyperthermia at a higher temperature inhibited the growth of carcinosarcoma at the site of treatment. Furthermore, the growth of the carcinosarcoma on the untreated side was also inhibited. The expression levels of proliferating cell nuclear antigen were decreased in the hyperthermia group, which was more significant in the higher temperature test group. Flow cytometric analysis showed an increased number of CD4- and CD8-positive T cells, and enzyme-linked immunosorbent assay showed increased levels of interferon-? and interleukin-2 in the higher temperature group. These results suggested that magnet-mediated hyperthermia at a higher temperature (50-55C) can improve the abscopal antitumor effects and stimulate a greater endogenous immune response in carcinosarcoma-bearing rats. PMID:24527084

  4. Targeted disruption of the Walker-Warburg syndrome gene Pomt1 in mouse results in embryonic lethality.

    PubMed

    Willer, Tobias; Prados, Beln; Falcn-Prez, Juan Manuel; Renner-Mller, Ingrid; Przemeck, Gerhard K H; Lommel, Mark; Coloma, Antonio; Valero, M Carmen; de Angelis, Martin Hrab; Tanner, Widmar; Wolf, Eckhard; Strahl, Sabine; Cruces, Jess

    2004-09-28

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

  5. A westward extension of the warm pool leads to a westward extension of the Walker circulation, drying eastern Africa

    NASA Astrophysics Data System (ADS)

    Williams, A. Park; Funk, Chris

    2011-12-01

    Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical Pacific, extending the tropical warm pool to the west by ~40 longitude (>4,000 km). This propensity toward rapid warming in the Indian Ocean has been the dominant mode of interannual variability among SSTs throughout the tropical Indian and Pacific Oceans (55E-140W) since at least 1948, explaining more variance than anomalies associated with the El Nio-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 Nio-like' conditions globally by the Intergovernmental Panel on Climate Change. Increased Indian Ocean SSTs appear likely to continue to strongly modulate the Warm Pool circulation, reducing precipitation in eastern Africa, regardless of whether the projected trend in ENSO is realized. These results have important food security implications, informing agricultural development, environmental conservation, and water resource planning.

  6. A 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

  7. Abscopal antitumor immune effects of magnet-mediated hyperthermia at a high therapeutic temperature on Walker-256 carcinosarcomas in rats

    PubMed Central

    WANG, HUI; ZHANG, LI; SHI, YINGRUI; JAVIDIPARSIJANI, SARA; WANG, GUIRONG; LI, XIAO; OUYANG, WEIWEI; ZHOU, JUMEI; ZHAO, LINGYUN; WANG, XIAOWEN; ZHANG, XIAODONG; GAO, FUPING; LIU, JINGSHI; LUO, JUNMING; TANG, JINTIAN

    2014-01-01

    The abscopal effect has previously been described in various tumors and is associated with radiation therapy and hyperthermia, with possible underlying mechanisms explaining each observed case. In the present study, we aimed to investigate the antitumor effects of magnet-mediated hyperthermia on Walker-256 carcinosarcomas in rats at two different temperature ranges (4246C and 5055C). We also aimed to identify whether a higher therapeutic temperature of magnetic-mediated hyperthermia improves the abscopal antitumor effects, where localised irradiation of the tumor causes not only the irradiated tumor to shrink, but also tumors located far from the area of irradiation. Following induction of carcinosarcoma in both sides of the body, magnet-mediated hyperthermia was applied to one side only, leaving the other side as a control. The changes in tumor growth were observed. Our results demonstrated that magnet-mediated hyperthermia at a higher temperature inhibited the growth of carcinosarcoma at the site of treatment. Furthermore, the growth of the carcinosarcoma on the untreated side was also inhibited. The expression levels of proliferating cell nuclear antigen were decreased in the hyperthermia group, which was more significant in the higher temperature test group. Flow cytometric analysis showed an increased number of CD4- and CD8-positive T cells, and enzyme-linked immunosorbent assay showed increased levels of interferon-? and interleukin-2 in the higher temperature group. These results suggested that magnet-mediated hyperthermia at a higher temperature (5055C) can improve the abscopal antitumor effects and stimulate a greater endogenous immune response in carcinosarcoma-bearing rats. PMID:24527084

  8. A province-scale block model of Walker Lane and western Basin and Range crustal deformation constrained by GPS observations (Invited)

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The Walker Lane in the western Great Basin of the western United States is an 800 km long and 100 km wide zone of active intracontinental transtension that absorbs ~10 mm/yr, about 20% of the Pacific/North America plate boundary relative motion. Lying west of the Sierra Nevada/Great Valley microplate (SNGV) and adjoining the Basin and Range Province to the east, deformation is predominantly shear strain overprinted with a minor component of extension. The Walker Lane responds with faulting, block rotations, structural step-overs, and has distinct and varying partitioned domains of shear and extension. Resolving these complex deformation patterns requires a long term observation strategy with a dense network of GPS stations (spacing ~20 km). The University of Nevada, Reno operates the 373 station Mobile Array of GPS for Nevada transtension (MAGNET) semi-continuous network that supplements coverage by other networks such as EarthScope's Plate Boundary Observatory, which alone has insufficient density to resolve the deformation patterns. Uniform processing of data from these GPS mega-networks provides a synoptic view and new insights into the kinematics and mechanics of Walker Lane tectonics. We present velocities for thousands of stations with time series between 3 to 17 years in duration aligned to our new GPS-based North America fixed reference frame NA12. The velocity field shows a rate budget across the southern Walker Lane of ~10 mm/yr, decreasing northward to ~7 mm/yr at the latitude of the Mohawk Valley and Pyramid Lake. We model the data with a new block model that estimates rotations and slip rates of known active faults between the Mojave Desert and northern Nevada and northeast California. The density of active faults in the region requires including a relatively large number of blocks in the model to accurately estimate deformation patterns. With 49 blocks, our the model captures structural detail not represented in previous province-scale models, and improves our ability to compare results to geologic fault slip rates. Modeling the kinematics on this scale has the advantages of 1) reducing the impact of poorly constrained boundaries on small geographically limited models, 2) consistent modeling of rotations across major structural step-overs near the Mina deflection and Carson domain, 3) tracking the kinematics of the south-to-north varying budget of Walker Lane deformation by solving for extension in the Basin and Range to the east, and 4) using a contiguous SNGV as a uniform western kinematic boundary condition. We compare contemporary deformation to geologic slip rates and longer term rotation rates estimated from rock paleomagnetism. GPS-derived block rotation rates are somewhat dependent on model regularization, but are generally within 1 per million years, and tend to be slower than published paleomagnetic rotations rates. GPS data, together with neotectonic and rock paleomagnetism studies provide evidence that the relative importance of Walker Lane block rotations and fault slip continues to evolve, giving way to a more through-going system with slower rotation rates and higher slip rates on individual faults.

  9. Recent crustal movements in the Sierra Nevada-Walker lane region of California-Nevada: Part i, rate and style of deformation

    USGS Publications Warehouse

    Slemmons, D.B.; Wormer, D.V.; Bell, E.J.; Silberman, M.L.

    1979-01-01

    This review of geological, seismological, geochronological and paleobotanical data is made to compare historic and geologic rates and styles of deformation of the Sierra Nevada and western Basin and Range Provinces. The main uplift of this region began about 17 m.y. ago, with slow uplift of the central Sierra Nevada summit region at rates estimated at about 0.012 mm/yr and of western Basin and Range Province at about 0.01 mm/yr. Many Mesozoic faults of the Foothills fault system were reactivated with normal slip in mid-Tertiary time and have continued to be active with slow slip rates. Sparse data indicate acceleration of rates of uplift and faulting during the Late Cenozoic. The Basin and Range faulting appears to have extended westward during this period with a reduction in width of the Sierra Nevada. The eastern boundary zone of the Sierra Nevada has an irregular en-echelon pattern of normal and right-oblique faults. The area between the Sierra Nevada and the Walker Lane is a complex zone of irregular patterns of ho??rst and graben blocks and conjugate normal-to right- and left-slip faults of NW and NE trend, respectively. The Walker Lane has at least five main strands near Walker Lake, with total right-slip separation estimated at 48 km. The NE-trending left-slip faults are much shorter than the Walker Lane fault zone and have maximum separations of no more than a few kilometers. Examples include the 1948 and 1966 fault zone northeast of Truckee, California, the Olinghouse fault (Part III) and possibly the almost 200-km-long Carson Lineament. Historic geologic evidence of faulting, seismologic evidence for focal mechanisms, geodetic measurements and strain measurements confirm continued regional uplift and tilting of the Sierra Nevada, with minor internal local faulting and deformation, smaller uplift of the western Basin and Range Province, conjugate focal mechanisms for faults of diverse orientations and types, and a NS to NE-SW compression axis (??1) and an EW to NW-SE extension axis (??3). ?? 1979.

  10. Wormhole spectrum of a quantum Friedmann-Robertson-Walker cosmology minimally coupled to a power-law scalar field and the cosmological constant

    SciTech Connect

    Kim, S.P. Department of Physics Education, College of Education, Seoul National University, Seoul 151-742 ); Page, D.N. )

    1992-05-15

    The expansion of the wave function of a quantum Friedmann-Robertson-Walker cosmology minimally coupled to a scalar field with a power-law potential by its scalar-field part decouples the gravitational-field part into an infinite system of linear homogeneous differential equations (equivalent to a matrix equation). The solutions for the gravitational-field part are found in the product integral formulation. It is shown that there exists a spectrum of the wave functions exponentially damped for large three-geometries under the condition that the cosmological constant should vanish. These are interpeted as the Hawking-Page wormholes.

  11. A pyroelectric infrared biometric system for real-time walker recognition by use of a maximum likelihood principal components estimation (MLPCE) method.

    PubMed

    Fang, Jian-Shuen; Hao, Qi; Brady, David J; Guenther, Bob D; Hsu, Ken Y

    2007-03-19

    This paper presents a novel biometric system for real-time walker recognition using a pyroelectric infrared sensor, a Fresnel lens array and signal processing based on the linear regression of sensor signal spectra. In the model training stage, the maximum likelihood principal components estimation (MLPCE) method is utilized to obtain the regression vector for each registered human subject. Receiver operating characteristic (ROC) curves are also investigated to select a suitable threshold for maximizing subject recognition rate. The experimental results demonstrate the effectiveness of the proposed pyroelectric sensor system in recognizing registered subjects and rejecting unknown subjects. PMID:19532568

  12. A pyroelectric infrared biometric system for real-time walker recognition by use of a maximum likelihood principal components estimation (MLPCE) method

    NASA Astrophysics Data System (ADS)

    Fang, Jian-Shuen; Hao, Qi; Brady, David J.; Guenther, Bob D.; Hsu, Ken Y.

    2007-03-01

    This paper presents a novel biometric system for real-time walker recognition using a pyroelectric infrared sensor, a Fresnel lens array and signal processing based on the linear regression of sensor signal spectra. In the model training stage, the maximum likelihood principal components estimation (MLPCE) method is utilized to obtain the regression vector for each registered human subject. Receiver operating characteristic (ROC) curves are also investigated to select a suitable threshold for maximizing subject recognition rate. The experimental results demonstrate the effectiveness of the proposed pyroelectric sensor system in recognizing registered subjects and rejecting unknown subjects.

  13. 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 following major historic earthquakes in the region. In particular we model the 1999 Hector Mine, 1992 Landers, 1952 Kern County, and 1872 Owens Valley earthquakes. GPS velocities adjusted for transient effects indicate that there is a distinct NW trend in the motions of the blocks with rates decreasing to the east. However, deformation rates are greater than zero east of the SWL in the Basin and Range. The preliminary results obtained from the block model indicate significant slip at the easternmost edge of the model, in the vicinity of Yucca Mountain and the Stateline fault.

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

    PubMed Central

    Williams, Paul T.; Thompson, Paul D.

    2013-01-01

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

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

    SciTech Connect

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

    2012-01-01

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

  16. 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 474.94g/ml as LC10-50 values. Numbers of total hemocytes, plasmatocytes and granulocytes as well as phenoloxidase activity increased in the different time intervals following treatment by hexaflumuron. Combined effects of hexaflumuron and Beauveria bassiana Vuillemin also increased hemocyte numbers and phenoloxidase activity at different time intervals using all concentrations. Activities of general esterases assayed by ?- and ?-naphtyl acetate and glutathione S-transferase using CDNB and DCNB increased 1-12h post-treatment. Activities of aspartate aminotransferase, alanine aminotransferase, ?-glutamyl transferase and aldolase increased in the larvae treated by hexaflumuron. However enhanced activity of lactate dehydrogenase was only obtained by treating 180 and 470g/ml concentrations of hexaflumuron. Activities of ACP and ALP were found to be higher than control for all time intervals even 1-12h post-treatment. The amounts of HDL and LDL increased in the highest concentrations of hexaflumuron after 12-24h of post-treatment. Amount of triglyceride was higher than that of control after 1 and 3h but it was lower in other time intervals. Amounts of glycogen and protein were lower than those of control for all time intervals except for 6 and 12h of post-treatment in case of protein. Results of the current study revealed negative effects of hexaflumuron on intermediary metabolism of Chilo suppressalis but it increased the number of hemocytes and activity of phenoloxidase which are responsible for spore removal from hemolymph. It can be concluded that hexaflumuron is able to decrease survival and biological performance of C. suppressalis via intervening in intermediary metabolism but the given results showed incompatibility of the IGR with possible microbial control. PMID:26615153

  17. 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 ...

  18. Using a walker

    MedlinePLUS

    ... Rizzo TD, eds. Essentials of Physical Medicine and Rehabilitation . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2015:chap ... M, Nielsen C eds. Orthotics and Prosthetics in Rehabilitation . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2013:chap ...

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

    PubMed

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

    2007-01-15

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

  20. 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

  1. 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.

  2. Paleomagnetism of the Stanislaus Group, CA reveals revised stratigraphy, Walker Lane kinematics, and radio-isotopic constraints on C5 magnetic subchrons

    NASA Astrophysics Data System (ADS)

    Pluhar, C. J.; Wright, T. J.; Fischer, C. P.; Busby, C. J.

    2007-12-01

    Paleomagnetic study of the c.a. 9.2-10.3 Ma Stanislaus Group of intercalated latite (trachyandesite) lavas, ignimbrites and accessory sediments at three localities in Mono county California reveals: 1) a detailed, revised stratigraphy for the Stanislaus group, 2) kinematic constraints on the part of the Walker Lane since Stanislaus group emplacement, and 3) two age-constrained magnetic subchrons during chron C5N recorded by latites that had previously only been identified in seafloor magnetic anomalies. The revised stratigraphy results from detailed magnetostratigraphy combined with previous 40Ar/39Ar geochronologic constraints and stratigraphic studies. We find the lowermost unit, Table Mountain Latite, to consist of 23 or more individual lava flows falling into 5 magnetic (mostly normal) polarity zones, indicating that these rocks span at least 40,000 years of geologic time, based on the expected duration of magnetic reversals. Overlying Table Mountain Latite is the reversed-polarity Tollhouse Flat member of the Eureka Valley Tuff as described by previous authors. In the Sweetwater Roadless Area, thought to be proximal to the Stanislaus eruptive center, latite lava of both normal and reversed polarity are emplaced ontop of the Tollhouse Flat Member. Normal-polarity By Day member and normal-polarity Upper Member lie at very top of entire sequence. We find no field evidence for the normal polarity Dardanelle Formation latite flow at the top of the Group as had been previously reported by other workers. Instead, the Dardanelle formation member likely corresponds to the latite lava(s) between the By Day and Tollhouse Flat Eureka Valley Tuff. Based on previous 40Ar/39Ar dating, the two reversed zones within our magnetostratigraphy correspond to two of the proposed reversed subchrons/excursions during chron C5N. Direct dating of these reversed units may lead to future improvements to the magnetic polarity timescale for C5N. Our paleomagnetic results from three study localities also reveals kinematic constraints for the boundary between the Sierra Nevada and central Walker Lane belt. The section at Sonora Peak, CA, within the stable Sierra Nevada microplate, yields a locality mean direction for these rocks indistinguishable from the expected direction for the late Miocene. The two other study localities, Grouse Meadow and Burcham Creek, lie within the western Walker Lane Belt, east of the Sierra Nevada range front fault zone. Results from these latter localities reveal 10-20 of vertical axis rotation of fault-bounded blocks of the western Walker Lane since emplacement of the Stanislaus Group. These results are obtained relative to a variety of datums - by averaging secular variation, by comparing locality mean directions from one place to another, and by comparing unit mean directions for the extensive e ignimbrites from one place to another. These results allow explicit delineation of the kinematic boundary between stable Sierra Nevada and the Walker Lane and geometrical calculation of total strain accommodated by these rotations.

  3. 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.

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

    SciTech Connect

    Schmid, Christoph

    2009-03-15

    We show that there is exact dragging of the axis directions of local inertial frames by a weighted average of the cosmological energy currents via gravitomagnetism for all linear perturbations of all Friedmann-Robertson-Walker (FRW) universes and of Einstein's static closed universe, and for all energy-momentum-stress tensors and in the presence of a cosmological constant. This includes FRW universes arbitrarily close to the Milne Universe and the de Sitter universe. Hence the postulate formulated by Ernst Mach about the physical cause for the time-evolution of inertial axes is shown to hold in general relativity for linear perturbations of FRW universes. - The time-evolution of local inertial axes (relative to given local fiducial axes) is given experimentally by the precession angular velocity {omega}-vector{sub gyro} of local gyroscopes, which in turn gives the operational definition of the gravitomagnetic field: B-vector{sub g}{identical_to}-2{omega}-vector{sub gyro}. The gravitomagnetic field is caused by energy currents J-vector{sub {epsilon}} via the momentum constraint, Einstein's G{sup 0-}circumflex{sub i-circumflex} equation, (-{delta}+{mu}{sup 2})A-vector{sub g}=-16{pi}G{sub N}J-vector{sub {epsilon}} with B-vector{sub g}=curl A-vector{sub g}. This equation is analogous to Ampere's law, but it holds for all time-dependent situations. {delta} is the de Rham-Hodge Laplacian, and {delta}=-curl curl for the vorticity sector in Riemannian 3-space. - In the solution for an open universe the 1/r{sup 2}-force of Ampere is replaced by a Yukawa force Y{sub {mu}}(r)=(-d/dr)[(1/R)exp(-{mu}r)], form-identical for FRW backgrounds with K=(-1,0). Here r is the measured geodesic distance from the gyroscope to the cosmological source, and 2{pi}R is the measured circumference of the sphere centered at the gyroscope and going through the source point. The scale of the exponential cutoff is the H-dot radius, where H is the Hubble rate, dot is the derivative with respect to cosmic time, and {mu}{sup 2}=-4(dH/dt). Analogous results hold in closed FRW universes and in Einstein's closed static universe.--We list six fundamental tests for the principle formulated by Mach: all of them are explicitly fulfilled by our solutions.--We show that only energy currents in the toroidal vorticity sector with l=1 can affect the precession of gyroscopes. We show that the harmonic decomposition of toroidal vorticity fields in terms of vector spherical harmonics X-vector{sub lm}{sup -} has radial functions which are form-identical for the 3-sphere, the hyperbolic 3-space, and Euclidean 3-space, and are form-identical with the spherical Bessel-, Neumann-, and Hankel functions. - The Appendix gives the de Rham-Hodge Laplacian on vorticity fields in Riemannian 3-spaces by equations connecting the calculus of differential forms with the curl notation. We also give the derivation the Weitzenboeck formula for the difference between the de Rham-Hodge Laplacian {delta} and the ''rough'' Laplacian {nabla}{sup 2} on vector fields.

  5. 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 Einsteins static closed universe, and for all energy-momentum-stress tensors and in the presence of a cosmological constant. This includes FRW universes arbitrarily close to the Milne Universe and the de Sitter universe. Hence the postulate formulated by Ernst Mach about the physical cause for the time-evolution of inertial axes is shown to hold in general relativity for linear perturbations of FRW universes.The time-evolution of local inertial axes (relative to given local fiducial axes) is given experimentally by the precession angular velocity ??gyro of local gyroscopes, which in turn gives the operational definition of the gravitomagnetic field: B?g?-2??gyro. The gravitomagnetic field is caused by energy currents J?? via the momentum constraint, Einsteins G0^i^ equation, (-?+?2)A?g=-16?GNJ?? with B?g=curlA?g. This equation is analogous to Ampres law, but it holds for all time-dependent situations. ? is the de Rham-Hodge Laplacian, and ?=-curlcurl for the vorticity sector in Riemannian 3-space.In the solution for an open universe the 1/r2-force of Ampre is replaced by a Yukawa force Y?(r)=(-d/dr)[(1/R)exp?(-?r)], form-identical for FRW backgrounds with K=(-1,0). Here r is the measured geodesic distance from the gyroscope to the cosmological source, and 2?R is the measured circumference of the sphere centered at the gyroscope and going through the source point. The scale of the exponential cutoff is the H-dot radius, where H is the Hubble rate, dot is the derivative with respect to cosmic time, and ?2=-4(dH/dt). Analogous results hold in closed FRW universes and in Einsteins closed static universe.We list six fundamental tests for the principle formulated by Mach: all of them are explicitly fulfilled by our solutions.We show that only energy currents in the toroidal vorticity sector with ?=1 can affect the precession of gyroscopes. We show that the harmonic decomposition of toroidal vorticity fields in terms of vector spherical harmonics X??m- has radial functions which are form-identical for the 3-sphere, the hyperbolic 3-space, and Euclidean 3-space, and are form-identical with the spherical Bessel-, Neumann-, and Hankel functions.The Appendix gives the de Rham-Hodge Laplacian on vorticity fields in Riemannian 3-spaces by equations connecting the calculus of differential forms with the curl notation. We also give the derivation the Weitzenbck formula for the difference between the de Rham-Hodge Laplacian ? and the rough Laplacian ?2 on vector fields.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    As the earth's population, industry, and agricultural systems continue to expand and increase demand for limited hydrologic resources, developing better tools for monitoring, analyzing and perhaps even predicting decadal variations in precipitation will enable the climate community to better inform important policy and management decisions. To this end, in support of the development and humanitarian relief efforts of the US Agency for International Development, USGS, NOAA, UC Santa Barbara, and NASA scientists have been exploring global precipitation trends using observations and new ensembles of atmospheric general circulation model (AGCM) simulations from the ECHAM5, GFSv2, CAM4 and GMAO models. This talk summarizes this work, and discusses how combined analyses of AGCM simulations and observations might lead to credible decadal projections, for some regions and seasons, based on the strength of the Indo-Pacific warming signal. Focusing on the late boreal spring, a critical period for food insecure Africa, we begin by linearly decomposing 1900-2012 sea surface temperatures (SST) into components loading strongly in the Indo-Western Pacific and Eastern Pacific. Eastern Pacific (EP) SST variations are based on regressions with three time series: the first and second principal components of equatorial Pacific SST and the Pacific Decadal Oscillation. These influences are removed from Indo-Pacific SSTs, and the Indo-Western Pacific (IWP) SST variations are defined by the 1st principal component of the residuals, which we refer to as the Indo-West Pacific Warming Signal (IWPWS). The pattern of IWPWS SST changes resembles recent assessments of centennial warming, and identifies rapid warming in the equatorial western Pacific and north and south Pacific convergence zones. The circulation impacts of IWP and EP SST forcing are explored in two ways. First, assuming linear SST forcing relationships, IWP and EP decompositions of ECHAM5, GFS, CAM4 and GMAO AGCM simulations are presented. These results suggest that a substantial component of the recent Walker circulation intensification has been related to the IWPWS. The IWPWS warming extends from just north of Papua New Guinea to just west of Hawaii, and appears associated with SLP, wind and rainfall responses consistent with enhanced Indo-Pacific convection. These decomposition results are compared with a set of numerical simulation experiments based on the ECHAM5 and GFS models forced with characteristic IWP and EP SST for 1983-1996 and 1999-2012. The talk concludes with a tentative discussion of the decadal predictability associated with the IWPWS. Using both observed and model-simulated precipitation, we briefly explore potential IWPWS drought teleconnection regions in the Americas, Asia, Middle East, and Eastern Africa. Figure 1. Western Pacific and Eastern Pacific SST changes between 1999-2012 and 1983-1996. Figure 2. Western Pacific and Eastern Pacific GPCP precipitation changes between 1999-2012 and 1983-1996.

  7. Geodetic vs. Geologic Measures of Fault Slip Rates in the Northern Walker Lane, Basin and Range Province, Western United States

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

    Quantifying faults slip rates and styles is an important objective in the study of crustal deformation. Fault slip rates are used to quantify seismic hazard associated with active faults, and are an important input into the U.S.G.S. seismic hazard maps. However, when multiple types of data (e.g. geologic, seismic and geodetic) are used to measure slip rates, results from the different techniques can be corroborative, complementary, or in direct conflict. Geologic methods provide some of the only constraints on slip rates of individual faults over hundreds to tens of thousands of years, time scales that are significant with respect to observed deformation patterns, and likely representative of modern hazard. On the other hand geodetic measurements provide strong constraints on the medium to long spatial wavelength (>50 km) budgets of deformation, and on geographic changes in deformation style, and have the potential to provide geographically complete measurements of surface deformation. However, geodetic measurements can be influenced by earthquake cycle effects, e.g. owing to interseismic fault locking and postseismic relaxation, which limit their ability to resolve individual slip rates, especially in complex systems with many closely spaced faults. The northern Walker Lane (NWL), in the western Basin and Range Province (BRP) of the United States, is an example of a complex system of dextral, normal and sinestral faults that work together to accommodate approximately 10 mm/yr of relative motion between the Sierra Nevada/Great Valley block and the central part of the BRP. To exploit the strengths of each dataset, we have built a detailed model of NWL crustal blocks and are using geodetic and geologic data to resolve patterns of crustal deformation. We use a block modeling technique that incorporates the strengths of both targeted geologic investigations of slip rates on individual faults and longer wavelength constraints offered by GPS geodesy. To constrain these models we use a compilation of GPS data from our own 163-site MAGNET GPS network plus regional continuous GPS sites from the Plate Boundary Observatory and BARGEN networks, and published USGS campaign velocities. For geologic data we have tabulated slip rate estimates into two categories, 1) published studies with quantitative rates valid in the Quaternary, and 2) the USGS Quaternary Fault and Fold Database that is a comprehensive web-available database with many reconnaissance level estimates of fault slip rate. Our modeling helps unravel the slip rate debate by distinguishing between system-wide discrepancies in integrated moment rate across the NWL, and point-wise discrepancies in individual fault slip rates. Our modeling shows that on the systemic level, even a single reliable geologic slip rate can improve the condition of the modeling, and on the individual fault level geodetic constraints can eliminate feasibility of some very high slip rates allowed by the geologic data. We conclude that for the NWL, the rate disagreement is attributable to an incomplete catalog of geologic slip rates and not to systematic underestimation of slip rates in the individual studies.

  8. 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 11.77.9 rotation of the presumed footwall. Our data corroborates and improves on Carlson's (2012) kinematic model in which the greater Bodie Hills has rotated clockwise ~30 since EVT emplacement. Eutaxitic textures, dipping up to 90, are gross indicators of true tilt, but are also influenced by original dips in some localities, complicating interpretations. John et al. (2012) describe a simple doming model of Bodie Hills since EVT emplacement, supported by the high elevation of outflow channels compared to source areas. Our paleomagnetic data does not support simple doming, suggesting that there is either no doming of Bodie Hills, or that vertical crustal displacements have occurred without large-scale folding. John et al. (2012) dated undifferentiated EVT in Bodie Hills at ~9.4 Ma; using paleomagnetism, we show the dated outcrops to be Tollhouse Flat Member, substantially improving age constraints on EVT.

  9. 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...

  10. 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

  11. 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.

  12. Process evaluation of the project P.A.T.H.S. (secondary 2 program): findings based on the co-walker scheme.

    PubMed

    Shek, Daniel T L; Tam, Suet-yan

    2009-01-01

    To understand the implementation quality of the Tier 1 Program (Secondary 2 Curriculum) of the P.A.T.H.S. Project, process evaluation was carried out by co-walkers through classroom observation of 195 units in 131 schools. Results showed that the overall level of program adherence was generally high with an average of 84.55%, and different factors of the implementation process were evaluated as positive. Quality of program implementation and achievement of program objectives were predicted by students' participation and involvement, strategies to enhance students' motivation, opportunity for reflection, time management, and class preparation. Success in program implementation was predicted by students' participation and involvement, classroom control, interactive delivery method, strategies to enhance students' motivation, opportunity for reflection, and lesson preparation. PMID:20432602

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

    PubMed Central

    2013-01-01

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

  14. 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.; Agi?, 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 ?18Ofluid during stromatolite formation. Our results show that the stromatolite experienced an overall increase in temperature and ?18Ofluid 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. 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.

  17. Rates and timing of vertical-axis block rotations across the central Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada

    NASA Astrophysics Data System (ADS)

    Rood, Dylan H.; Burbank, Douglas W.; Herman, Scott W.; Bogue, Scott

    2011-10-01

    We use paleomagnetic data from Tertiary volcanic rocks to address the rates and timing of vertical-axis block rotations across the central Sierra Nevada-Walker Lane transition in the Bodie Hills, California/Nevada. Samples from the Upper Miocene (9 Ma) Eureka Valley Tuff suggest clockwise vertical-axis block rotations between NE-striking left-lateral faults in the Bridgeport and Mono Basins. Results in the Bodie Hills suggest clockwise rotations (R ?R, 95% confidence limits) of 74 8 since Early to Middle Miocene (12-20 Ma), 42 11 since Late Miocene (8-9 Ma), and 14 10 since Pliocene (3 Ma) time with no detectable northward translation. The data are compatible with a relatively steady rotation rate of 5 2 Ma-1 (2?) since the Middle Miocene over the three examined timescales. The average rotation rates have probably not varied by more than a factor of two over time spans equal to half of the total time interval. Our paleomagnetic data suggest that block rotations in the region of the Mina Deflection began prior to Late Miocene time (9 Ma), and perhaps since the Middle Miocene if rotation rates were relatively constant. Block rotation in the Bodie Hills is similar in age and long-term average rate to rotations in the Transverse Ranges of southern California associated with early transtensional dextral shear deformation. We speculate that the age of rotations in the Bodie Hills indicates dextral shear and strain accommodation within the central Walker Lane Belt resulting from coupling of the Pacific and North America plates.

  18. High-Precision Locations and the Stress Field from Instrumental Seismicity, Moment Tensors, and Short-Period Mechanisms through the Mina Deflection, Central Walker Lane

    NASA Astrophysics Data System (ADS)

    Ruhl, C. J.; Smith, K. D.

    2012-12-01

    The Mina Deflection (MD) region of the central Walker Lane of eastern California and western Nevada, is a complex zone of northeast-trending normal, and primarily left-lateral strike-slip to oblique-slip faulting that separates the Southern Walker Lane (SWL) from a series of east-tilted normal fault blocks in the Central Walker Lane (CWL) (Faulds and Henry, 2008; Surpless, 2008). The MD accommodates the transfer of right-lateral strike-slip motion from northwest-striking faults in the SWL to a series of left-stepping northwest-striking right-lateral strike-slip faults in the CWL, east of the Wassuk Range near Hawthorne, NV. The ~50 km wide ~80 km long right-step is a distinct transition in regional physiography that has been attributed to strain accommodation through pre-Cenozoic lithospheric structures. Several slip transfer mechanisms have been proposed within the MD, from clockwise rotation of high-angle fault blocks (Wesnousky, 2005), to low-angle displacement within the Silver Peak-Lone Mountain complex (Oldow et al., 2001), and curved fault arrays associated with localized basins and tectonic depressions (Ferranti et al., 2009). The region has been a regular source of M4+ events, the most recent being an extended sequence that included twenty-seven M 3.5+ earthquakes (largest event M 4.6) south of Hawthorne in 2011. These earthquakes (< 5 km depth) define shallow W-dipping (dip ~56°) and NW-dipping (dip ~70°) normal faulting constrained by moment tensor (MT) solutions and earthquake relocations. Temporary stations deployed in the source area provide good control. A distributed sequence in 2004, between Queen Valley and Mono Lake, primarily associated with the Huntoon Valley fault, included three M 5+ left-lateral strike-slip faulting events. A 1997 sequence in northern Fish Lake Valley (east of the White Mountains), with mainshock Mw 5.3 (Ichinose et al., 2003), also showed high-angle northeast-striking left-lateral strike-slip motion. Historical events include the 1934 M 6.5 Excelsior Mountains event south of Mina, NV, and the 1932 M 7.1 Cedar Mountains earthquake east of the Pilot Mountains. Another persistent feature in the seismicity is an ~40 km long arcuate distribution of activity extending from approximately Queen Valley, north of the White Mountains, to Mono Lake that appears to reflect a southwestern boundary to northeast-striking structures in the MD. Here we develop high-precision relocations of instrumental seismicity in the MD from 1984 through 2012, including relocations of the 2004 sequence, and account for the historical seismic record. MT solutions from published reports and computed from recent M 3.5+ earthquakes as well as available and developed short-period focal mechanisms are compiled to evaluate the stress field to assess mechanisms of slip accommodation. Based on the complex distribution of fault orientations, the stress field varies locally northward from the SWL throughout the MD; however, in many cases, fault plane alignments can be isolated from high-precision locations, providing better constraints on stress and slip orientations.

  19. Different Phenotypes of Walker-Like A Box Mutants of ParA Homolog IncC of Broad-Host-Range IncP Plasmids

    PubMed Central

    Siddique, Azeem; Figurski, David H.

    2012-01-01

    The promiscuous IncP? plasmids RK2 and R995 encode a broad-host-range partition system, whose essential components include the incC and korB genes and a DNA site (OB) to which the korB product binds. IncC2, the smaller of the two incC products, is sufficient for stabilization of R995?incC. It is a member of the type Ia ParA family of partition ATPases. To better understand the role of ATP in partition, we constructed three alanine-substitution mutants of IncC2. Each mutation changed a different residue of the Walker-like ATP-binding and hydrolysis motif, including a lysine (K10) conserved solely among members of the ParA and MinD families. All three IncC2 mutants were defective in plasmid partition, but they differed from one another in other respects. The IncC2 T16A mutant, predicted to be defective in Mg2+ coordination, was severely impaired in all activities tested. IncC2 K10A, predicted to be defective in ATP hydrolysis, mediated enhanced incompatibility with R995 derivatives. IncC2 K15A, predicted to be defective in ATP binding, exhibited two distinct incompatibility properties depending on the genotype of the target plasmid. When in trans to plasmids carrying a complementable incC deletion, IncC2 K15A caused dramatic plasmid loss, even at low levels of expression. In trans to wild-type R995 or to R995?incC carrying a functional P1 partition system, IncC2 K15A-mediated incompatibility was significantly less than that caused by wild-type IncC2. All three Walker-like A box mutants were also defective for the host toxicity that normally results from co-overexpression of incC and korB. The phenotypes of the mutants support a model in which nucleotide hydrolysis is required for separation of paired plasmid complexes and possible interaction with a host factor. PMID:22579980

  20. West End Walkers 65+: A randomised controlled trial of a primary care-based walking intervention for older adults: Study rationale and design

    PubMed Central

    2011-01-01

    Background In Scotland, older adults are a key target group for physical activity intervention due to the large proportion who are inactive. The health benefits of an active lifestyle are well established but more research is required on the most effective interventions to increase activity in older adults. The 'West End Walkers 65+' randomised controlled trial aims to examine the feasibility of delivering a pedometer-based walking intervention to adults aged ≥65 years through a primary care setting and to determine the efficacy of this pilot. The study rationale, protocol and recruitment process are discussed in this paper. Methods/Design The intervention consisted of a 12-week pedometer-based graduated walking programme and physical activity consultations. Participants were randomised into an immediate intervention group (immediate group) or a 12-week waiting list control group (delayed group) who then received the intervention. For the pilot element of this study, the primary outcome measure was pedometer step counts. Secondary outcome measures of sedentary time and physical activity (time spent lying/sitting, standing or walking; activPAL™ monitor), mood (Positive and Negative Affect Schedule), functional ability (Perceived Motor-Efficacy Scale for Older Adults), quality of life (Short-Form (36) Health Survey version 2) and loneliness (UCLA Loneliness Scale) were assessed. Focus groups with participants and semi-structured interviews with the research team captured their experiences of the intervention. The feasibility component of this trial examined recruitment via primary care and retention of participants, appropriateness of the intervention for older adults and the delivery of the intervention by a practice nurse. Discussion West End Walkers 65+ will determine the feasibility and pilot the efficacy of delivering a pedometer-based walking intervention through primary care to Scottish adults aged ≥65 years. The study will also examine the effect of the intervention on the well-being of participants and gain an insight into both participant and research team member experiences of the intervention. Trial registration number ISRCTN: ISRCTN70658148 PMID:21333020

  1. Numerical simulations of depressurization-induced gas production from gas hydrate reservoirs at the Walker Ridge 312 site, northern Gulf of Mexico

    SciTech Connect

    Myshakin, Evgeniy M.; Gaddipati, Manohar; Rose, Kelly; Anderson, Brian J.

    2012-06-01

    In 2009, the Gulf of Mexico (GOM) Gas Hydrates Joint-Industry-Project (JIP) Leg II drilling program confirmed that gas hydrate occurs at high saturations within reservoir-quality sands in the GOM. A comprehensive logging-while-drilling dataset was collected from seven wells at three sites, including two wells at the Walker Ridge 313 site. By constraining the saturations and thicknesses of hydrate-bearing sands using logging-while-drilling data, two-dimensional (2D), cylindrical, r-z and three-dimensional (3D) reservoir models were simulated. The gas hydrate occurrences inferred from seismic analysis are used to delineate the areal extent of the 3D reservoir models. Numerical simulations of gas production from the Walker Ridge reservoirs were conducted using the depressurization method at a constant bottomhole pressure. Results of these simulations indicate that these hydrate deposits are readily produced, owing to high intrinsic reservoir-quality and their proximity to the base of hydrate stability. The elevated in situ reservoir temperatures contribute to high (540 MMscf/day) predicted production rates. The production rates obtained from the 2D and 3D models are in close agreement. To evaluate the effect of spatial dimensions, the 2D reservoir domains were simulated at two outer radii. The results showed increased potential for formation of secondary hydrate and appearance of lag time for production rates as reservoir size increases. Similar phenomena were observed in the 3D reservoir models. The results also suggest that interbedded gas hydrate accumulations might be preferable targets for gas production in comparison with massive deposits. Hydrate in such accumulations can be readily dissociated due to heat supply from surrounding hydrate-free zones. Special cases were considered to evaluate the effect of overburden and underburden permeability on production. The obtained data show that production can be significantly degraded in comparison with a case using impermeable boundaries. The main reason for the reduced productivity is water influx from the surrounding strata; a secondary cause is gas escape into the overburden. The results dictate that in order to reliably estimate production potential, permeability of the surroundings has to be included in a model.

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

    PubMed

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

    2007-02-01

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

  3. ATP Regulation of Type-1 Inositol 1,4,5-Trisphosphate Receptor Activity Does Not Require Walker A-type ATP-binding Motifs*

    PubMed Central

    Betzenhauser, Matthew J.; Wagner, Larry E.; Park, Hyung Seo; Yule, David I.

    2009-01-01

    ATP is known to increase the activity of the type-1 inositol 1,4,5-trisphosphate receptor (InsP3R1). This effect is attributed to the binding of ATP to glycine rich Walker A-type motifs present in the regulatory domain of the receptor. Only two such motifs are present in neuronal S2+ splice variant of InsP3R1 and are designated the ATPA and ATPB sites. The ATPA site is unique to InsP3R1, and the ATPB site is conserved among all three InsP3R isoforms. Despite the fact that both the ATPA and ATPB sites are known to bind ATP, the relative contribution of these two sites to the enhancing effects of ATP on InsP3R1 function is not known. We report here a mutational analysis of the ATPA and ATPB sites and conclude neither of these sites is required for ATP modulation of InsP3R1. ATP augmented InsP3-induced Ca2+ release from permeabilized cells expressing wild type and ATP-binding site-deficient InsP3R1. Similarly, ATP increased the single channel open probability of the mutated InsP3R1 to the same extent as wild type. ATP likely exerts its effects on InsP3R1 channel function via a novel and as yet unidentified mechanism. PMID:19386591

  4. Prenatal Diagnosis of WalkerWarburg Syndrome Using Single Nucleotide Polymorphism Array: A Clinical Experience from Three Related Palestinian Families with Congenital Hydrocephalus

    PubMed Central

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

    2015-01-01

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

  5. 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

  6. Characterization of calcium transport in the luminal and the basolateral membrane from kidney cortex of hypercalcemic rats bearing the Walker 256 carcinosarcoma.

    PubMed

    de Miguel, F; Esbrit, P

    1993-10-01

    The Walker 256 (W256) carcinosarcoma did not significantly modify calcium uptake by brush border membrane (BBM) vesicles in the kidney of the host rat, compared with that in membranes isolated from control animals. However, it showed a tendency to increase at near equilibrium in W256 tumor-host rats, associated with a decreased BBM protein content. ATP-dependent calcium influx by basolateral membrane (BLM) vesicles from W256 tumor-bearing rats was also increased compared with that in control BLM. This stimulation was due to a decreased Km for calcium. Passive calcium permeability or the Na+/Ca2+ exchanger were unchanged in BLM from W256 tumor-host rats compared with control BLM. Pre-stimulation of control rat cortical tubules with either 10(-7) M parathyroid hormone-related protein (PTHrP) (1-34) or 10(-4) M N6,2'-O-dibutiryl cyclic AMP before BLM isolation, did not modify the ATP-dependent calcium uptake by BLM vesicles compared with control membranes. However, our results do not rule out that the stimulated ATP-dependent calcium influx in BLM from W256 tumor-host rats could be mediated by the interaction among PTHrP and other humoral factors. Our findings suggest a possible mechanism for the increased renal calcium reabsorption in this animal model for humoral hypercalcemia of malignancy. PMID:8274881

  7. 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

  8. Enzymatic properties of alpha-amylase in the midgut and the salivary glands of mulberry moth, Glyphodes pyloalis Walker (Lepidoptera: Pyralidae).

    PubMed

    Yezdani, Elham; Sendi, Jalal Jalali; Zibaee, Arash; Ghadamyari, Mohammad

    2010-01-01

    The pyralid moth, Glyphode pyloalis Walker, is an important pest of the mulberry. Amylases are the hydrolytic enzymes that catalyze the hydrolysis of the alpha-D-(1,4)-glucan linkage in glycogen and other related carbohydrates. Laboratory-reared fifth stadium larvae were randomly selected; the midgut (MG) and the salivary glands (SG) were removed by dissection under a dissecting microscope and alpha-amylase activity was assayed using the dinitrosalicylic acid procedure. The activity of alpha-amylase in the MG and the SG were 0.011 and 0.0018 micromol/min, respectively. The optimal pH and temperature for alpha-amylase were 9 for MG at 37-40 degrees C and 10 for SG at 37 degrees C respectively. Various concentrations of compounds (NaCl, KCl, MgCl(2), Urea, EDTA, SDS and CaCl(2)) had differential effects on the enzyme activity. Plant amylase inhibitors may play an important role against insect pests. Hence, the characterization of digestive enzymes and the examination of their inhibitors may be a useful tool in future management of this important mulberry pest. PMID:20176331

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

    PubMed Central

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

    2011-01-01

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

  10. Efficacy of five volatile oils and their mixtures against the soft scale insect, Saissetia coffeae (Walker) (Hemiptera: Coccidae) infesting the Sago palm, Cycas revoluta in Alexandria, Egypt.

    PubMed

    Mesbah, H A; Nagda, A El Sayed; Mourad, A K; Abdel-Razak, I Soad; Samar, E Abd El-Rahman

    2010-01-01

    Five tested plant volatile oils and their mixtures were evaluated for controlling the coccid, Saissetia coffeae (Walker) on growing Sago palms Cycas revoluta in Antoniades public gardens, Alexandria, Egypt. The tested volatile oils at concentration rates of 0.5, 1 and 1.5% (v/v) were: Camphor 20%, Dill 20%, Rose 30%, Peppermint 20% and Clove 30% (v/v). Their mixtures were : Camphor/Peppermint, Camphor/Rose at a rate of 1:1, Camphor/Rose/Peppermint at 1:1:2 rate and Camphor/Rose/Dill at 2:1:1 rate. The results, as a general mean of residual reduction percent for the whole inspection intervals of the test lasted 2 days up to 9 days post treatment, indicated that the superior volatile oils in reducing the insect were both Camphor and Rose, followed by Dill, Peppermint and the least efficient one was the Clove oil. The evaluated mixtures of the volatile oils showed that each of Camphor/Rose/Peppermint, Camphor/Rose and Camphor/Peppermint mixtures attained a higher rank of efficiency against that of the assigned soft scale insect. PMID:21539257

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

    PubMed Central

    2013-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  13. 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 explained by partial melting of a single mantle source, with Cordilleran-type enrichments, but no special K enrichments in any particular region. Moreover, just as low F melts are enriched in K, Pb, or U, they will also be enriched in water, which greatly reduces magma density (Ochs and Lange, 1999). Such differences in water contents provide a mechanism for regional variations in volcanic compositions: depth-integrated density models show that dry mafic magmas have insufficient buoyancy to erupt from beneath thick crust, but low F (water-enriched) melts are sufficiently buoyant to allow eruption. Theoretical models (Takada, 1994) further indicate that tensile stress regimes favor the transport of low F melts. Thus, where the crust is thick, such as in the southern Sierra Nevada, only low F magmas can erupt, due to their natural water enrichments and added buoyancy, and even then are probably only erupted when tensile stresses favor their segregation from their source region. In our alternative interpretation then, high-K volcanism reflects the inception of transtensional stresses, recording the birth of a plate boundary.

  14. 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

  15. Progressive brainstem compression in an infant with neurocutaneous melanosis and Dandy-Walker complex following ventriculoperitoneal shunt placement for hydrocephalus. Case report.

    PubMed

    McClelland, Shearwood; Charnas, Lawrence R; SantaCruz, Karen S; Garner, Hart P; Lam, Cornelius H

    2007-12-01

    Neurocutaneous melanosis (NM) coexisting with the Dandy-Walker complex (DWC) is a rare condition, with fewer than 15 cases reported in the literature. The authors present a case of an infant with NM and DWC suffering from progressive brainstem compression following ventriculoperitoneal (VP) shunt placement for hydrocephalus. This 1-year-old boy with congenital melanocytic nevi had met normal developmental milestones until the age of 11 months, when he began regressing in ambulation and language function. Intractable vomiting had developed 1 week later. Magnetic resonance (MR) imaging of the brain revealed DWC with hydrocephalus, and spinal MR images demonstrated a proliferative process within the meninges, consistent with NM. The patient underwent right frontal VP shunt placement resulting in immediate symptom relief, but 3 weeks later became irritable, increasingly lethargic, unable to pull to stand, and unable to tolerate solid food without choking. Due to these symptoms and intractable vomiting, the patient presented to the authors' institution. Brain MR imaging revealed a new-onset diffuse cystic process with anterior and posterior brainstem compression, marked kinking of the cervicomedullary junction, melanocyte pigmentation of the left temporal lobe, diffuse leptomeningeal enhancement, and no evidence of hydrocephalus. Consistent with these imaging findings, the degree of brainstem involvement upon gross visualization predictably deterred resection attempts beyond those necessary for biopsy. Pathological examination revealed diffuse melanocytosis, and the family decided not to pursue aggressive measures postoperatively. This report indicates the potential for rapid intracranial manifestation of diffuse melanocytosis in NM patients. Although the prognosis is poor, early neurosurgical involvement in these patients may provide tissue diagnosis and the potential for decompression if the process is caught early in its course. PMID:18154021

  16. Fish oil supplementation in F1 generation associated with naproxen, clenbuterol, and insulin administration reduce tumor growth and cachexia in Walker 256 tumor-bearing rats.

    PubMed

    Pinto, Joo A; Folador, Alessandra; Bonato, Sandro J; Aikawa, Jlia; Yamazaki, Ricardo K; Pizato, Natalia; Facin, Mirela; Grohs, Hans; de Oliveira, Helosa H P; Naliwaiko, Katya; Ferraz, Anete C; Nishiyama, Anita; Fernandez, Ricardo; Curi, Rui; Fernandes, Luiz C

    2004-06-01

    Weanling female Wistar rats were supplemented with fish oil (1 g/kg body weight) for one generation. The male offspring received the same supplementation until to adult age. Rats supplemented with coconut fat were used as reference. Some rats were inoculated subcutaneously with a suspension (2 x 10(7) cells/mL) of Walker 256 tumor. At day 3, when the tumor was palpable, rats were treated with naproxen (N) (0.1 mg/mL), clenbuterol (Cb) (0.15 mg/kg body weight), and insulin (I) (10 U/kg body weight). At day 14 after tumor inoculation, the animals were killed. Tumor was removed and weighed. Blood, liver, and skeletal muscles were also collected for measurements of metabolites and insulin. In both tumor-bearing untreated rats and tumor-bearing rats supplemented with coconut fat, tumor growth, triacylglycerol, and blood lactate levels were higher, and glycogen content of the liver, blood glucose, cholesterol and HDL-cholesterol levels were lower as compared with the non-tumor-bearing and fish oil supplemented groups. Fish oil supplementation of tumor-bearing rats led to a partial recovery of the glycogen content in the liver and a full reversion of blood glucose, lactate, cholesterol, and HDL-cholesterol levels. The treatment with N plus Cb plus I attenuated cancer cachexia and decreased tumor growth in both coconut fat and fish oil supplemented rats. In conclusion, chronic fish oil supplementation decreased tumor growth and partially recovered cachexia. This beneficial effect of fish oil supplementation was potentiated by treatment with naproxen plus clenbuterol plus insulin. PMID:15157942

  17. 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; Lvero, 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; Muscar, Marcelo Nicols; 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-? 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-? 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

  18. Cosmological perturbations of brane-induced gravity and the van Dam-Veltman-Zakharov discontinuity on Friedmann-Lemaitre-Robertson-Walker space-times

    SciTech Connect

    Deffayet, Cedric

    2005-05-15

    We investigate the cosmological perturbations of the brane-induced (Dvali-Gabadadze-Porrati) model which exhibits a van Dam-Veltman-Zakharov (vDVZ) discontinuity when linearized over a Minkowski background. We show that the linear brane scalar cosmological perturbations over an arbitrary Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time have a well defined limit when the radius of transition between 4D and 5D gravity is sent to infinity with respect to the background Hubble radius. This radius of transition plays for the brane-induced gravity model a role equivalent to the Compton wavelength of the graviton in a Pauli-Fierz theory, as far as the vDVZ discontinuity is concerned. This well defined limit is shown to obey the linearized 4D Einstein's equations whenever the Hubble factor is nonvanishing. This shows the disappearance of the vDVZ discontinuity for general FLRW background, and extends the previously know result for maximally-symmetric space-times of nonvanishing curvature. Our reasoning is valid for matter with simple equation of state such as a scalar field, or a perfect fluid with adiabatic perturbations, and involves to distinguish between space-times with a vanishing scalar curvature and space-times with a nonvanishing one. We also discuss the validity of the linear perturbation theory, in particular, for those FLRW space-times where the Ricci scalar is vanishing only on a set of zero measure. In those cases, we argue that the linear perturbation theory breaks down when the Ricci scalar vanishes (and the radius of transition is sent to infinity), in a way similar to what has been found to occur around sources on a Minkowski background.

  19. Re-assigned diagnosis of D4ST1-deficient Ehlers-Danlos syndrome (adducted thumb-clubfoot syndrome) after initial diagnosis of Marden-Walker syndrome.

    PubMed

    Winters, Kevin A; Jiang, Zhijie; Xu, Weihong; Li, Shibo; Ammous, Zineb; Jayakar, Parul; Wierenga, Klaas J

    2012-11-01

    We report on a 16-year-old female originally diagnosed with Marden-Walker syndrome due to features such as facial dysmorphism, several musculoskeletal anomalies, and atrial septal defect in addition to hypoplasia of the inferior vermis with normal-sized cerebellum and absence of the septum pellucidum. However, an SNP array performed at age 15 years detected a total of 142?Mb of long runs of homozygosity (ROH), and put the diagnosis in doubt. Using the Genomic Oligoarray and SNP array evaluation tool (http://www.ccs.miami.edu/ROH), CHST14 provided a "hit" as a gene mapping to the largest ROH region associated with a phenotype matching our patient's (if mutated). At that time, she was a cognitively intact, thin female with growth parameters below the 3rd percentile. Craniofacial features included microcephaly, midface hypoplasia, blepharophimosis, entropion, myopia, microretrognathia, and dental malocclusion. Musculoskeletal features included kyphoscoliosis, arachnodactyly, camptodactyly, and rocker-bottom feet with interphalangeal contractures. Her skin displayed large ecchymoses and poorly healed atrophic scars. Sequencing of CHST14 revealed a complex homozygous frameshift mutation involving a 7-bp deletion and an 11-bp insertion predicted to produce a truncated protein. This mutation was not seen in 100 controls of various ethnicities. Thus, our patient represents not only a novel (homozygous) mutation in CHST14, but is also the first patient with dermatan 4-O-sulfotransferase 1-deficient Ehlers-Danlos syndrome (adducted thumb-clubfoot syndrome) (DD-EDS ATCS) documented in the Western Hemisphere. Furthermore, our patient's central nervous system anomalies have not before been described in DD-EDS (ATCS). PMID:22987394

  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. 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, ?95 = 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, ?95 = 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.

  3. Translation vs. Rotation: The Battle for Accommodation of Dextral Shear at the Northern Terminus of the Central Walker Lane, Western Nevada

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Positioned between the Sierra Nevada microplate and Basin and Range in western North America, the Walker Lane (WL) accommodates ~20% of the dextral motion between the North American and Pacific plates on predominately NW-striking dextral and ENE to E-W-striking sinistral fault systems. The Terrill Mountains (TM) lie at the northern terminus of a domain of dextral faults accommodating translation of crustal-blocks in the central WL and at the southeast edge of sinistral faults accommodating oroclinal flexure and CW rotation of blocks in the northern WL. As the mechanisms of strain transfer between these disparate fault systems are poorly understood, the thick Oligocene to Pliocene volcanic strata of the TM area make it an ideal site for studying the transfer of strain between regions undergoing differing styles of deformation and yet both accommodating dextral shear. Detailed geologic mapping and paleomagnetic study of ash-flow tuffs in the TM region has been conducted to elucidate Neogene strain accommodation for this transitional region of the WL. Strain at the northernmost TM appears to be transferred from a system of NW-striking dextral faults to a system of ~E-W striking sinistral faults with associated CW flexure. A distinct ~23 Ma paleosol is locally preserved below the tuff of Toiyabe and provides an important marker bed. This paleosol is offset with ~6 km of dextral separation across the fault bounding the NE flank of the TM. This fault is inferred as the northernmost strand of the NW-striking, dextral Benton Spring fault system, with offset consistent with minimums constrained to the south (6.4-9.6 km, Gabbs Valley Range). Paleomagnetic results suggest counter-intuitive CCW vertical-axis rotation of crustal blocks south of the domain boundary in the system of NW-striking dextral faults, similar to some other domains of NW-striking dextral faults in the northern WL. This may result from coeval dextral shear and WNW-directed extension within the left-stepping system of dextral fault. The left steps are analogous to Riedel shears developing above a more through-going shear zone at depth. However, a site directly adjacent to the Benton Springs fault is rotated ~30° CW, likely due to fault drag. These results show the complex and important contribution of vertical-axis rotations in accommodation of dextral shear.

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

  5. Antitumor and anti-cachectic effects of shark liver oil and fish oil: comparison between independent or associative chronic supplementation in Walker 256 tumor-bearing rats

    PubMed Central

    2013-01-01

    Background Shark liver oil (SLOil) and fish oil (FOil), which are respectively rich in alkylglycerols (AKGs) and n-3 polyunsaturated fatty acids (PUFAs), are able to reduce the growth of some tumors and the burden of cachexia. It is known that FOil is able to reduce proliferation rate and increase apoptotic cells and lipid peroxidation of tumor cells efficiently. However, there are few reports revealing the influence of SLOil on these parameters. In the current study, effects of FOil chronic supplementation on tumor growth and cachexia were taken as reference to compare the results obtained with SLOil supplementation. Also, we evaluated if the association of SLOil and FOil was able to promote additive effects. Methods Weanling male Wistar rats were divided into 4 groups: fed regular chow (C), supplemented (1?g/kg body weight) with SLOil (CSLO), FOil (CFO) and both (CSLO?+?FO). After 8 weeks half of each group was inoculated with Walker 256 cells originating new groups (W, WSLO, WFO and WSLO?+?FO). Biochemical parameters of cachexia, tumor weight, hydroperoxide content, proliferation rate and percentage of apoptotic tumor cells were analysed. Fatty acids and AKG composition of tumor and oils were obtained by high performance liquid chromatography and gas chromatography mass spectrometry, respectively. Statistical analysis was performed by unpaired t-test and one-way ANOVA followed by a post hoc Tukey test. Results Fourteen days after inoculation, SLOil was able to restore cachexia parameters to control levels, similarly to FOil. WSLO rats presented significantly lower tumor weight (40%), greater tumor cell apoptosis (~3-fold), decreased tumor cell proliferation (35%), and higher tumor content of lipid hydroperoxides (40%) than observed in W rats, but FOil showed more potent effects. Supplementation with SLOil?+?FOil did not promote additive effects. Additionally, chromatographic results suggested a potential incorporation competition between the n-3 fatty acids and the AKGs in the tumor cells membranes. Conclusions SLOil is another marine source of lipids with similar FOil anti-cachectic capacity. Furthermore, despite being less potent than FOil, SLOil presented significant in vivo antitumor effects. These results suggest that the chronic supplementation with SLOil may be adjuvant of the anti-cancer therapy. PMID:24131597

  6. A wrist-walker exhibiting no "Uner Tan Syndrome": a theory for possible mechanisms of human devolution toward the atavistic walking patterns.

    PubMed

    Tan, Uner

    2007-01-01

    After discovering two families with handicapped children exhibiting the "Uner Tan syndrome," the author discovered a man exhibiting only wrist-walking with no primitive mental abilities including language. According to his mother, he had an infectious disease with high fever as a three months old baby; as a result, the left leg had been paralyzed after a penicilline injection. This paralysis most probably resulted from a viral disease, possibly poliomyelitis. He is now (2006) 36 years old; the left leg is flaccid and atrophic, with no tendon reflexes; however, sensation is normal. The boy never stood up on his feet while maturing. The father forced him to walk upright using physical devices and making due exercises, but the child always rejected standing upright and walking in erect posture; he always preferred wrist-walking; he expresses that wrist-walking is much more comfortable for him than upright-walking. He is very strong now, making daily body building exercises, and walking quite fast using a "three legs," although he cannot stand upright. Mental status, including the language and conscious experience, is quite normal. There was no intra-familiar marriage as in the two families mentioned earlier, and there is no wrist-walking in his family and relatives. There were no cerebellar signs and symptoms upon neurological examination. The brain-MRI was normal; there was no atrophy in cerebellum and vermis. It was concluded that there may be sporadic wrist-walkers exhibiting no "Uner Tan Syndrome." The results suggest that the cerebellum has nothing to do with human wrist-walking, which may rather be an atavistic trait appearing from time to time in normal individuals, indicating a live model for human reverse evolution. It was concluded that pure quadrupeds may sporadically appear due to random fluctuations in genotypes and/or environmental factors (hormonal or nutritional); the human development following the human evolution may be stopped in the stage of transition from quadrupedality to bipedality. That is, the activity of the philogenetically youngest supraspinal centers for bipedal walking responsible for suppression of the older supraspinal centers for quadrupedal gait may be interrupted at the atavistic level due to genetic and/or environmental factors. Consequently, it is assumed that these individuals prefer their natural wrist-walking to move around more quickly and efficiently. PMID:17365105

  7. Collective motion of oscillatory walkers

    NASA Astrophysics Data System (ADS)

    Ezaki, Takahiro; Nishi, Ryosuke; Yanagisawa, Daichi; Nishinari, Katsuhiro

    2013-07-01

    We study a system of interacting self-propelled particles whose walking velocity depends on the stage of the locomotion cycle. The model introduces a phase equation in the optimal velocity model for vehicular traffic. We find that the system exhibits novel types of flow: synchronized free flow, phase-anchoring free flow, orderly jam flow, and disordered jam flow. The first two flows are characterized by synchronization of the phase, while the others do not have the global synchronization. Among these, the disordered jam flow is very complex, although the underlying model is simple. This phenomenon implies that the crowd behavior of moving particles can be destabilized by coupling their velocity to the phase of their motion. We also focus on phase-anchoring phenomena. They strongly affect particle flow in the system, especially when the density of particles is high.

  8. 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 ...

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

    PubMed

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

    2015-05-01

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

  10. Genetics Home Reference: Walker-Warburg syndrome

    MedlinePLUS

    ... protein called alpha (?)-dystroglycan; this modification, called glycosylation, is required for ?-dystroglycan to function. The ... during early development. Mutations in these genes prevent glycosylation of ?-dystroglycan, which disrupts its normal function. ...

  11. Genetics Home Reference: Walker-Warburg syndrome

    MedlinePLUS

    ... modify another protein called alpha (α)-dystroglycan; this modification, called glycosylation, is required for α-dystroglycan to ... Center . Where can I find general information about genetic conditions? The Handbook provides basic information about genetics ...

  12. 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)

  13. Genetics Home Reference: Dandy-Walker malformation

    MedlinePLUS

    ... about genetic testing , particularly the difference between clinical tests and research tests . To locate a healthcare provider, see How can ... and researchers. Genetic Testing Registry - Repository of genetic test information (1 link) ClinicalTrials.gov - Linking patients to ...

  14. Do Exercise Walkers Need Special Walking Shoes?

    ERIC Educational Resources Information Center

    Barnes, Lan

    1987-01-01

    The emergence of exercise walking as a popular fitness activity has spurred sales of shoes designed and marketed specifically for walking. Consumers may find comfort and stability in these shoes--but certain other shoes may work as well. (Author)

  15. 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.

  16. Competitive Brownian and Lévy walkers

    NASA Astrophysics Data System (ADS)

    Heinsalu, E.; Hernández-García, E.; López, C.

    2012-04-01

    Population dynamics of individuals undergoing birth and death and diffusing by short- or long-range two-dimensional spatial excursions (Gaussian jumps or Lévy flights) is studied. Competitive interactions are considered in a global case, in which birth and death rates are influenced by all individuals in the system, and in a nonlocal but finite-range case in which interaction affects individuals in a neighborhood (we also address the noninteracting case). In the global case one single or few-cluster configurations are achieved with the spatial distribution of the bugs tied to the type of diffusion. In the Lévy case long tails appear for some properties characterizing the shape and dynamics of clusters. Under nonlocal finite-range interactions periodic patterns appear with periodicity set by the interaction range. This length acts as a cutoff limiting the influence of the long Lévy jumps, so that spatial configurations under the two types of diffusion become more similar. By dividing initially everyone into different families and following their descent it is possible to show that mixing of families and their competition is greatly influenced by the spatial dynamics.

  17. 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…

  18. 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 Owens Valley and Coso regions which have larger amounts of shortening and elongation of the finite strain axes without substantial rotation, caused by the narrowness of the high strain corridor in these two regions. The variation of coaxial to noncoaxial strain ratios among predominantly coaxially dominated strain provinces results in variations in shape among finite strain ellipsoids. K-values for each structural province plot above the k=1 diagonal on the logarithmic Flinn (Ramsay) diagram, indicating prolate non-plane transtensional strain. Plate tectonic reconstruction of Sierran microplate motion over the last 3 My shows characteristic occurrence of areas of zone boundary parallel transport with intervening pull-aparts that correspond to centers of volcanism, magmatism, and subsidence. The nature of rotation of the microplate around its Euler pole, and adjacent tectonic block geometry and behavior are possible mechanisms for systematic widening of the higher strain transtensional corridor to the north. Collectively, these theoretical applications and structural-tectonic observations in the ECSZ-WL have significant implications for the kinematics of brittle deformation and evolution of this actively developing transtensional plate boundary.

  19. 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

  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.

  1. Effective trapping of random walkers in complex networks

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  2. 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,

  3. 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.

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

    PubMed Central

    Schilling, Malte; Paskarbeit, Jan; Hoinville, Thierry; Hffmeier, 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

  5. 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.

  6. Coupled uncertainty provided by a multifractal random walker

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  7. 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

  8. Vicious walkers and Young tableaux I: without walls

    NASA Astrophysics Data System (ADS)

    Guttmann, Anthony J.; Owczarek, Aleksander L.; Viennot, Xavier G.

    1998-10-01

    We rederive previously known results for the number of star and watermelon configurations by showing that these follow immediately from standard results in the theory of Young tableaux and integer partitions. In this way we provide a proof of a result, previously only conjectured, for the total number of stars.

  9. 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...

  10. Neotectonics, Geodesy and Seismic Hazard in the Northern Walker Lane

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    The establishment of fleets of large numbers of ocean bottom seismometers (OBS) capable of recording for more than a year has made it possible to study Earth structure beneath the oceans using seismic observations in much greater resolution than previously possible. However, shallow water poses strong challenges for OBS deployments, with much higher noise levels from waves and currents. The on-going Cascadia Initiative, a major OBS community project directed at studying the Cascadia subduction zone with its megathrust earthquake potential and broad continental shelf, includes OBS deployments at depths as shallow as 50 m. Before the Cascadia deployment, there was a valid fear that the data from the shallowest sites would be useless for seismic observations. The shallow Cascadia OBS deployments feature shielding to protect the sensors from the flow of ocean floor currents (and trawling), The first year data show that the shielding can reduce horizontal component noise levels (due to currents) by more than 20dB permitting good SNR for horizontal phases even at shelf depths. Noise from deformation under ocean wave loading has been found to be very large at the shallowest sites. High amplitude ocean waves cause the differential pressure gauges (DPG) and unshielded seismic sensors at a few sites to sometimes clip, but shielded seismic sensors and pressure measurements from absolute pressure gauges (APGs) remain unclipped even at the shallowest sites. The study demonstrates pressure gauge records can be used to predict and remove the noise from the deformation under ocean wave loading in the spectral domain, potentially improving signal to noise for long period seismic phases by up to 40dB. A FIR digital filter can be created from the pressure to acceleration transfer function that when convolved with the pressure record accurately predicts the wave loading signal allowing removal of about 30dB of this noise. These results show that with proper shielding, good quality seismometer observations can be obtained from shallow water, opening up this critical part of the seafloor to observations for the first time. The data also show that without the use of pressure gauges to remove the wave loading noise, and without shielding, the shallow water, long period (>10s) data are almost useless for seismology.

  11. Comment on ''Walker diffusion method for calculation of transport properties of composite materials''

    SciTech Connect

    Kim, In Chan; Cule, Dinko; Torquato, Salvatore; Department of Chemistry, Princeton University, Princeton, New Jersey 08544

    2000-04-01

    In a recent paper [C. DeW. Van Siclen, Phys. Rev. E 59, 2804 (1999)], a random-walk algorithm was proposed as the best method to calculate transport properties of composite materials. It was claimed that the method is applicable both to discrete and continuum systems. The limitations of the proposed algorithm are analyzed. We show that the algorithm does not capture the peculiarities of continuum systems (e.g., ''necks'' or ''choke points'') and we argue that it is the stochastic analog of the finite-difference method. (c) 2000 The American Physical Society.

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

    ERIC Educational Resources Information Center

    Senn, Corelyn F.

    2002-01-01

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

  13. Thinking While Walking: Experienced High-Heel Walkers Flexibly Adjust Their Gait

    PubMed Central

    Schaefer, Sabine; Lindenberger, Ulman

    2013-01-01

    Theories of motor-skill acquisition postulate that attentional demands of motor execution decrease with practice. Hence, motor experts should experience less attentional resource conflict when performing a motor task in their domain of expertise concurrently with a demanding cognitive task. We assessed cognitive and motor performance in high-heel experts and novices who were performing a working memory task while walking in gym shoes or high heels on a treadmill. Surprisingly, neither group showed lower working memory performance when walking than when sitting, irrespective of shoe type. However, high-heel experts adapted walking regularity more flexibly to shoe type and cognitive load than novices, by reducing the variability of time spent in the single-support phase of the gait cycle in high heels when cognitively challenged. We conclude that high-heel expertise is associated with more flexible adjustments of movement patterns. Future research should investigate whether a more demanding walking task (e.g., wearing high heels on uneven surfaces and during gait perturbations) results in expertise-related differences in the simultaneous execution of a cognitive task. PMID:23760158

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

    PubMed

    Yin, Lim Khai; Rajeswari, Mandava

    2014-01-01

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

  15. Random walkers with extreme value memory: modelling the peak-end rule

    NASA Astrophysics Data System (ADS)

    Harris, Rosemary J.

    2015-05-01

    Motivated by the psychological literature on the ‘peak-end rule’ for remembered experience, we perform an analysis within a random walk framework of a discrete choice model where agents’ future choices depend on the peak memory of their past experiences. In particular, we use this approach to investigate whether increased noise/disruption always leads to more switching between decisions. Here extreme value theory illuminates different classes of dynamics indicating that the long-time behaviour is dependent on the scale used for reflection; this could have implications, for example, in questionnaire design.

  16. Spatial foraging in free ranging bearded sakis: traveling salesmen or Lévy Walkers?

    PubMed

    Shaffer, Christopher A

    2014-05-01

    According to optimal foraging theory and most current models of primate socioecology, primate foraging involves a series of decisions concerning when is the most optimal time to leave a food patch, how to travel to the next patch in an efficient manner, and how to minimize the time and distance traveled to all patches throughout the course of the day. In this study, I assess how bearded sakis solve these challenges by presenting data on their patch use, distance minimization, and by comparing their movements with non-deterministic foraging patterns. The study group, composed of 38 ± 15 individuals, fed significantly longer in higher quality patches (quality defined by patch size and productivity) and in those that contained ripe fruit pulp. However, group size was not a significant predictor of patch occupancy. Bearded sakis traveled relatively directly between food patches, sometimes over distances > 300 m. In addition, they chose the optimal daily path among all patches visited on 9 of 17 occasions, and on average traveled only 21% more than the least distance route. Bearded saki step lengths were consistent with a Brownian rather than a Lévy Walk pattern while waiting times were consistent with a Lévy pattern. However, the distribution of their turning angles indicated a high degree of directional persistence between patches. These results suggest that bearded sakis exploit food patches that are randomly distributed spatially but heterogenous in patch quality. They appear to encode the locations of high quality food patches and minimize travel between them, despite opportunistically feeding from more abundant and randomly distributed, lower quality patches en route. PMID:24166852

  17. Navel Orangeworm (Amyelois transitella) (Walker) and Obliquebanded Leafroller (Choristoneura rosaceana)(Harris) as Pests of Pistachio

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The navel orangeworm moved into California in 1942 from Mexico and by 1949 was present throughout the state. This moth is the primary pest of pistachios and almonds in California and causes direct damage by feeding on the kernel. Infestation reduces yield, increases aflatoxin contamination, primaril...

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

    ERIC Educational Resources Information Center

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

    2007-01-01

    Walking without vision results in veering, an inability to maintain a straight path that has important consequences for blind pedestrians. In this study, the authors addressed whether the source of veering in the absence of visual and auditory feedback is better attributed to errors in perceptual encoding or undetected motor error. Three

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

    ERIC Educational Resources Information Center

    Senn, Corelyn F.

    2002-01-01

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

  20. New Walkers with Down Syndrome Use Cautious but Effective Strategies for Crossing Obstacles

    ERIC Educational Resources Information Center

    Mulvey, Genna M.; Kubo, Masayoshi; Chang, Chia-Lin; Ulrich, Beverly D.

    2011-01-01

    Perception of affordances research in children with developmental disabilities has only examined well practiced skills. Ten toddlers with Down syndrome and 10 with typical development walked across a GAITRite mat, with and without an obstacle. We coded the toddlers' behaviors after 1 and 3 months of walking experience when they encountered the