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1

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

PubMed

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

Barrantes, M E; Castelo, M K

2014-06-01

2

Joseph (Joe) A. Walker  

NASA Technical Reports Server (NTRS)

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.

1956-01-01

3

Evaluation of Walkers for Elderly People.  

National Technical Information Service (NTIS)

The aim of this study was to evaluate three types of walkers for elderly people, Four elderly patients participated in the study. The experiments were performed using three walkers: a familiar conventional folding walker, a caster walker and a power-assis...

T. Tamura M. Sekine H. Kuno M. Fujie A. Mori

2001-01-01

4

Walker-Warburg syndrome  

PubMed Central

Walker-Warburg Syndrome (WWS) is a rare form of autosomal recessive congenital muscular dystrophy associated with brain and eye abnormalities. WWS has a worldwide distribution. The overall incidence is unknown but a survey in North-eastern Italy has reported an incidence rate of 1.2 per 100,000 live births. It is the most severe form of congenital muscular dystrophy with most children dying before the age of three years. WWS presents at birth with generalized hypotonia, muscle weakness, developmental delay with mental retardation and occasional seizures. It is associated with type II cobblestone lissencephaly, hydrocephalus, cerebellar malformations, eye abnormalities and congenital muscular dystrophy characterized by hypoglycosylation of ?-dystroglycan. Several genes have been implicated in the etiology of WWS, and others are as yet unknown. Several mutations were found in the Protein O-Mannosyltransferase 1 and 2 (POMT1 and POMT2) genes, and one mutation was found in each of the fukutin and fukutin-related protein (FKRP) genes. Laboratory investigations usually show elevated creatine kinase, myopathic/dystrophic muscle pathology and altered ?-dystroglycan. Antenatal diagnosis is possible in families with known mutations. Prenatal ultrasound may be helpful for diagnosis in families where the molecular defect is unknown. No specific treatment is available. Management is only supportive and preventive.

Vajsar, Jiri; Schachter, Harry

2006-01-01

5

Intelligently Controllable Walker with Magnetorheological Fluid Brake  

NASA Astrophysics Data System (ADS)

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.

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

6

Obituary: Robert Mowbray Walker, 1929-2004  

Microsoft Academic Search

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.

Neil T. Schoenherr

2004-01-01

7

Soils of Walker Branch Watershed  

Microsoft Academic Search

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

Lietzke

1994-01-01

8

Walker Branch Watershed Ecosystems Data  

DOE Data Explorer

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

9

X-1A with pilot Joe Walker  

NASA Technical Reports Server (NTRS)

Cowboy Joe (NACA High-Speed Flight Station test pilot Joseph Walker) and his steed (Bell Aircraft Corporation X-1A) A happy Joe was photographed in 1955 at Edwards, California. The X-1A was flown six times by Bell Aircraft Company pilot Jean 'Skip' Ziegler in 1953. Air Force test pilots Maj. Charles 'Chuck' Yeager and Maj. Arthur 'Kit' Murray made 18 flights between 21 November 1953 and 26 August 1954. The X-1A was then turned over to the NACA. Joe Walker piloted the first NACA flight on 20 July 1955. Walker attemped a second flight on 8 August 1955, but an explosion damaged the aircraft just before launch. Walker, unhurt, climbed back into the JTB-29A mothership, and the X-1A was jettisoned over the Edwards AFB bombing range.

1955-01-01

10

General transformation formulas for Fermi Walker coordinates  

NASA Astrophysics Data System (ADS)

We calculate the transformation and inverse transformation, in the form of Taylor expansions, from arbitrary coordinates to Fermi Walker coordinates in tubular neighborhoods of arbitrary timelike paths for general spacetimes. Explicit formulae for coefficients and the Jacobian matrix are given.

Klein, David; Collas, Peter

2008-07-01

11

Active faulting in the Walker Lane  

NASA Astrophysics Data System (ADS)

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.

Wesnousky, Steven G.

2005-06-01

12

Soils of Walker Branch Watershed  

SciTech Connect

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

Lietzke, D.A. [Lietzke Soil Services, Rutledge, TN (United States)

1994-03-01

13

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

Microsoft Academic Search

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,

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

2000-01-01

14

Soils of Walker Branch Watershed  

SciTech Connect

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.

Lietzke, D.A.

1994-01-01

15

Attitudes to and use of baby walkers in Dublin  

Microsoft Academic Search

OBJECTIVES: To identify the rate of baby walker use, parental attitudes, and associated injuries. DESIGN: Parents of babies attending clinics for developmental assessment were surveyed by self administered questionnaire about their use, attitudes, and history of injuries associated with walkers. SETTING: Dublin, Ireland. SUBJECTS: Parents of 158 babies. RESULTS: Fifty five per cent of the sample used a walker. The

M. Laffoy; P. Fitzpatrick; M. Jordan; D. Dowdall

1995-01-01

16

Gender Recognition from Point-Light Walkers  

ERIC Educational Resources Information Center

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…

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

2005-01-01

17

Baby walkers . . . time to take a stand?  

Microsoft Academic Search

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

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

1987-01-01

18

The Kneed Walker for human pose tracking  

Microsoft Academic Search

The Kneed Walker is a physics-based model derived from a planar biomechanical characterization of human locomo- tion. By controlling torques at the knees, hips and torso, th e model captures a full range of walking motions with foot contact and balance. Constraints are used to properly han- dle ground collisions and joint limits. A prior density over walking motions is

Marcus A. Brubaker; David J. Fleet

2008-01-01

19

Walker River Paiutes: A Tribal History.  

ERIC Educational Resources Information Center

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…

Johnson, Edward C.

20

Transcription of Walker 256 Carcinosarcoma Chromatin1  

Microsoft Academic Search

SUMMARY The in vitro transcriptions from chromatins of Walker256 carcinosarcoma, rat mammary gland, and rat liver were compared with respect to template activities and reciprocal double saturation hybridization of the transcribed RNA's. Walkertumor chromatin was found to have the least template activity in RNA synthesis in vitro, and the synthesized RNA, when annealed with DNA, also showed the least saturation

Nina C. Kostraba; T. Y. Wang

1971-01-01

21

Unusual manifestation of Marden-Walker syndrome  

PubMed Central

Marden-Walker syndrome (MWS) is characterized by multiple joint contractures, a mask-like face with blepharophimosis, micrognathia, high-arched or cleft palate, low-set ears, decreased muscular bulk, arachnodactyly, and kyphoscoliosis. We report a case of MWS along with unusual manifestation of neurological, cardiovascular, and genitourinary system.

Taksande, Amar M.; Vilhekar, K. Y.

2012-01-01

22

Neurosurgical management of Walker-Warburg syndrome  

Microsoft Academic Search

The Walker-Warburg syndrome (WWS) is a lethal complex of the central nervous system and the eyes. At present its cause is unknown, but clinical evidence strongly suggests that it is an autosomalrecessively inherited disorder. We report a series of nine children with WWS. The diagnosis was established by the detection of lissencephaly, hydrocephalus, and cerebellar malformation on computed tomography. All

J. F. Martínez-Lage; M. Poza; J. M. García Santos; Alberto Puche; Carlos Casas; Trinidad Rodriguez Costa

1995-01-01

23

Brownian walkers within subdiffusing territorial boundaries  

NASA Astrophysics Data System (ADS)

Inspired by the collective phenomenon of territorial emergence, whereby animals move and interact through the scent marks they deposit, we study the dynamics of a 1D Brownian walker in a random environment consisting of confining boundaries that are themselves diffusing anomalously. We show how to reduce, in certain parameter regimes, the non-Markovian, many-body problem of territoriality to the analytically tractable one-body problem studied here. The mean square displacement (MSD) of the 1D Brownian walker within subdiffusing boundaries is calculated exactly and generalizes well known results when the boundaries are immobile. Furthermore, under certain conditions, if the boundary dynamics are strongly subdiffusive, we show the appearance of an interesting nonmonotonicity in the time dependence of the MSD, giving rise to transient negative diffusion.

Giuggioli, L.; Potts, J. R.; Harris, S.

2011-06-01

24

Space Walker - the Cognitive Visualization System  

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

25

Active walker models: tracks and landscapes  

NASA Astrophysics Data System (ADS)

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

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

1992-12-01

26

Hybrid zero dynamics of planar biped walkers  

Microsoft Academic Search

Planar, underactuated, biped walkers form an important domain of applications for hybrid dynamical systems. This paper presents the design of exponentially stable walking controllers for general planar bipedal systems that have one degree-of-freedom greater than the number of available actuators. The within-step control action creates an attracting invariant set - a two-dimensional zero dynamics submanifold of the full hybrid model

E. R. Westervelt; J. W. Grizzle; D. E. Koditschek

2003-01-01

27

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

USGS Publications Warehouse

The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. The only outflow from Walker Lake is evaporation from the lake surface. Between 1882 and 2008, upstream agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-feet. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes streamflow in the Walker River basin and an updated water budget of Walker Lake with emphasis on the lower Walker River basin downstream from Wabuska, Nevada. Water budgets are based on average annual flows for a 30-year period (1971-2000). Total surface-water inflow to the upper Walker River basin upstream from Wabuska was estimated to be 387,000 acre-feet per year (acre-ft/yr). About 223,000 acre-ft/yr (58 percent) is from the West Fork of the Walker River; 145,000 acre-ft/yr (37 percent) is from the East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) is from the Sweetwater Range; and 2,000 acre-ft/yr (less than 1 percent) is from the Bodie Mountains, Pine Grove Hills, and western Wassuk Range. Outflow from the upper Walker River basin is 138,000 acre-ft/yr at Wabuska. About 249,000 acre-ft/yr (64 percent) of inflow is diverted for irrigation, transpired by riparian vegetation, evaporates from lakes and reservoirs, and recharges alluvial aquifers. Stream losses in Antelope, Smith, and Bridgeport Valleys are due to evaporation from reservoirs and agricultural diversions with negligible stream infiltration or riparian evapotranspiration. Diversion rates in Antelope and Smith Valleys were estimated to be 3.0 feet per year (ft/yr) in each valley. Irrigated fields receive an additional 0.8 ft of precipitation, groundwater pumpage, or both for a total applied-water rate of 3.8 ft/yr. The average corrected total evapotranspiration rate for alfalfa is 3.2 ft/yr so about 0.6 ft/yr (15 percent) flushes salts from the soil. The diversion rate in Bridgeport Valley was estimated to be 1.1 ft/yr and precipitation is 1.3 ft/yr. The total applied-water rate of 2.4 ft/yr is used to irrigate pasture grass. The total applied water rate in the East Fork of the Walker River and Mason Valley was estimated to be 4.8 ft/yr in each valley. The higher rate likely is due to appreciable infiltration, riparian evapotranspiration, or both. Assuming a diversion rate of 3.0 ft/yr, stream loss due to infiltration and riparian evapotranspiration is about 3,000 acre-ft/yr along the East Fork of the Walker River and 14,000 acre-ft/yr in Mason Valley. In the lower Walker River basin, overall and groundwater budgets were calculated for Wabuska to Schurz, Nev., and Schurz to Walker Lake. An overall water budget was calculated for the combined reaches. Imbalances in the water budgets range from 1 to 7 percent, which are insignificant statistically, so the water budgets balance. Total inflow to the Wabuska-Walker Lake reach from the river and others sources is 140,000 acre-ft/yr. Stream and subsurface discharge into the northern end of Walker Lake totals 110,000 acre-ft/yr. About 30,000 acre-ft/yr is lost on the Walker River Indian Reservation from agricultural evapotranspiration, evapotranspiration by native and invasive vegetation, domestic pumpage, and subsurface outflow from the basin through Double Spring and the Wabuska lineament. Alfalfa fields in the upper Walker River basin are lush and have an average corrected total evapotranspiration rate of 3.2 ft/yr. Alfalfa fields on the Walker River Indian Reservation are not as lush and have a total corrected evapotranspiration rate of 1.6-2.1 ft/yr, which partly could be due to alkaline soils that were submerged by Pleistocene Lake Lahontan. The total applied-water rate is 7.0 ft/yr, almost twice the

Lopes, Thomas J.; Allander, Kip K.

2009-01-01

28

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

29

Time Walkers and Spatial Dynamics of Aging Information  

NASA Astrophysics Data System (ADS)

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

Lizana, L.; Rosvall, M.; Sneppen, K.

2010-01-01

30

Quantum Cohomology via Vicious and Osculating Walkers  

NASA Astrophysics Data System (ADS)

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

Korff, Christian

2014-07-01

31

Hazards of baby walkers in a European context  

Microsoft Academic Search

OBJECTIVES: To identify conditions related to baby walker injuries in a Greek population. DESIGN: Analysis of all baby walker related injuries recorded during a 12 month period by the childhood injury surveillance system established in one of the two teaching hospitals for children serving the population of Athens. SETTING: Emergency clinics of A Kyriakou Children's Hospital in Athens, Greece. SUBJECTS:

E. Petridou; E. Simou; C. Skondras; G. Pistevos; P. Lagos; G. Papoutsakis

1996-01-01

32

Two cases of Walker-Warburg syndrome complicated by hydrocephalus.  

PubMed

Walker-Warburg syndrome is a very rare autosomal recessive disorder with congenital muscular dystrophy, brain malformations on the basis of a neuronal migration defect and ocular abnormalities. We report our experience in treating two cases of Walker-Warburg syndrome complicated by hydrocephalus with shunting and endoscopic techniques. PMID:20516736

Preuss, M; Heckmann, M; Stein, M; Nestler, U

2010-01-01

33

Older Homebound Women: Negotiating Reliance on a Cane or Walker  

PubMed Central

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.

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

2012-01-01

34

Designing stimulus-sensitive colloidal walkers.  

PubMed

Colloidal particles with DNA "legs" that can bind reversibly to receptors on a surface can be made to 'walk' if there is a gradient in receptor concentration. We use a combination of theory and Monte Carlo simulations to explore how controllable parameters, e.g. coating density and binding strength, affect the dynamics of such colloids. We find that competition between thermodynamic and kinetic trends imply that there is an optimal value for both the binding strength and the number of "legs" for which transport is the fastest. Using available thermodynamic data on DNA binding, we indicate how directionally reversible, temperature-controlled transport of colloidal walkers can be achieved. In particular, the present results should make it possible to design a chromatographic technique that can be used to separate colloids with different DNA functionalizations. PMID:24647520

Martinez-Veracoechea, Francisco J; Mognetti, Bortolo M; Angioletti-Uberti, Stefano; Varilly, Patrick; Frenkel, Daan; Dobnikar, Jure

2014-05-21

35

Familial Dandy-Walker malformation and leukodystrophy.  

PubMed

We report the first familial cases with two different types of posterior fossa cystic malformation and a leukodystrophic-like aspect on cerebral magnetic resonance imaging (MRI). The girl and her brother had severe encephalopathy, marked hypotonia, absent deep tendon reflexes, macrocrania, gigantism, and dysmorphic face and extremities. The girl had generalized seizures. The boy had unilateral cataract and bilateral optic atrophy. The parents were first cousins, suggesting autosomal recessive transmission. MRI showed Dandy-Walker variant in the girl, with cerebellar vermis hypoplasia and expansion of the cisterna magna, which communicated with the fourth ventricle. Her brother had mega cisterna magna communicating with the fourth ventricle and a normal cerebellum. The 2 children had abnormally high signal in the supratentorial white matter. Visual and auditory evoked potentials revealed prolonged latencies. Motor and sensory conduction velocities were normal. Muscle and nerve biopsies were normal. Metabolic exploration demonstrated no abnormality. PMID:9258968

Humbertclaude, V T; Coubes, P A; Leboucq, N; Echenne, B B

1997-05-01

36

Intelligent control of a smart walker and its performance evaluation.  

PubMed

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

Grondin, Simon L; Li, Qingguo

2013-06-01

37

Test pilots 1952 - Walker, Butchart, and Jones  

NASA Technical Reports Server (NTRS)

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.

1952-01-01

38

ISS Update: Orion Recovery and Rescue Lead Tom Walker  

NASA Video Gallery

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

39

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

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

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

40

Pilot Joe Walker and the X-1A  

NASA Technical Reports Server (NTRS)

Cowboy Joe (NACA High-Speed Flight Station test pilot Joseph Walker) and his steed (Bell Aircraft Corporation X-1A). A happy Joe was photographed in 1955 at Edwards, California. The X-1A was flown six times by Bell Aircraft Company pilot Jean 'Skip' Ziegler in 1953. Air Force test pilots Major Charles 'Chuck' Yeager and Major Arthur 'Kit' Murray made 18 flights between November 21, 1953 and August 26, 1954. The X-1A was then turned over to the NACA. Joe Walker piloted the first NACA flight on July 20, 1955. Walker attemped a second flight on August 8, 1955, but an explosion damaged the aircraft just before launch. Walker, unhurt, climbed back into the JTB-29A mothership, and the X-1A was jettisoned over the Edwards AFB bombing range.

1955-01-01

41

ENSO, Atlantic Climate Variability, and the Walker and Hadley Circulations.  

National Technical Information Service (NTIS)

The paper describes and discusses the Walker and Hadley circulations associated with the El Nino-Southern Oscillation (ENSO), the Atlantic Nino, the tropical Atlantic meridional gradient variability, the Western Hemisphere warm pool (WHWP), and the North ...

C. Wang

2003-01-01

42

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

NASA Technical Reports Server (NTRS)

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.

1995-01-01

43

STS-69 Mission Commander David M. Walker suits up  

NASA Technical Reports Server (NTRS)

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.

1995-01-01

44

Bose-Einstein condensation on closed Robertson-Walker spacetimes  

Microsoft Academic Search

In this letter we summarize our analysis of Bose-Einstein condensation on closed Robertson-Walker spacetimes. In a previous work we defined an adiabatic KMS state on the Weyl-algebra of the free massive Klein-Gordon field [M. Trucks, M. Keyl, Phys. Lett. B 399 (1997) 223, M. Trucks, Commun. Math. Phys. 197 (1998) 387]. This state describes a free Bose gas on Robertson-Walker

M. Trucks

1998-01-01

45

Basic walker-assisted gait characteristics derived from forces and moments exerted on the walker's handles: Results on normal subjects  

Microsoft Academic Search

This paper describes a method that passively assesses basic walker-assisted gait characteristics using only force-moment measurements from the walker's handles. The passively derived gait characteristics of 22 subjects were validated against motion capture gait analysis. The force-moment based heel initial contact detection algorithm have produced a high level of concordance with heel initial contacts detected by a human inspecting the

Majd Alwan; Alexandre Ledoux; Glenn Wasson; Pradip Sheth; Cunjun Huang

2007-01-01

46

Reservoir description, Walker Creek field, Arkansas  

SciTech Connect

A multidisciplinary reservoir description of Walker Creek field in southern Arkansas was conducted to evaluate the field's potential and determine the best method of increasing recovery. The reservoir is within a 100-ft-thick section of the ooid grainstone facies of the Jurassic Smackover Formation. The reservoir is currently under partial pressure maintenance by reinjection of produced gas at the crest of the structure. One of the goals of the study was to evaluate reservoir management options for effecting significant incremental oil recovery. The reservoir was originally divided into five producing zones (1-5). Of these, zones 2 and 4 account for nearly 95% of the production. The grainstone facies in zones 2 and 4 consist predominantly of ooids, but also contain peloids, oncolites, and intraclasts. Calcite cement creates discontinuous tight streaks throughout the reservoir. Porosity is predominantly intergranular and ranges from 1% to greater than 20%. Permeability also varies widely, ranging from 0.1 to > 5000 md. Five percent porosity and 0.6 md permeability, as determined by log analysis, were used as a net pay cutoff. Data from lithologic and log analyses were used to construct cross sections across the field. These sections and grainstone isopach maps illustrate that the two main reservoir zones represent two generations of prograding ooid shoal development. Calcite cemented intervals within the zones cannot be correlated beyond two or three wells. The local extent of these intervals does not justify using them to further subdivide the reservoir zones. Gross pay, net pay, and {delta}h maps indicate that development of porosity followed the trend and distribution of the ooid shoals. Production data (pressure plots, gas-to-oil-ratio maps, and tracer studies) suggest that individual reservoir zones are in communication across the field. These results led to a decision against infill drilling in the field.

Bliefnick, D.M.; Frey, K.M.; Dang, Thu-Thuy (ARCO Oil and Gas Co., Plano, TX (USA)); Bissmeyer, S.M. (ARCO Oil and Gas Co., Lafayette, LA (USA))

1990-05-01

47

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

ERIC Educational Resources Information Center

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

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

48

Adaptive controller for motion control of an omni-directional walker  

Microsoft Academic Search

Walking is a vital exercise for health promotion and a fundamental ability necessary for everyday life. In the authors' previous studies, an omni-directional walker was developed for walking rehabilitation. Walking training programs are stored in the walker and the walker must precisely follow the paths defined in the walking training programs to guarantee the effectiveness of rehabilitation. In the previous

Renpeng Tan; Shuoyu Wang; Yinlai Jiang; K. Ishida; M. Nagano

2010-01-01

49

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

Federal Register 2010, 2011, 2012, 2013

...Administration [TA-W-72,471] The Walker Auto Group, Inc., Miamisburg, OH; Notice...filed on behalf of workers at The Walker Auto Group, Inc., Miamisburg, Ohio, was...be eligible for TAA because the Walker Auto Group, Inc., Miamisburg, Ohio,...

2010-05-05

50

Bathymetry of Walker Lake, West-Central Nevada  

USGS Publications Warehouse

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.

Lopes, Thomas J.; Smith, J. LaRue

2007-01-01

51

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

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

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

52

Talking Back with Walker Gibson: Helping Students Gauge Tone.  

ERIC Educational Resources Information Center

Considers how inviting students to play Walker Gibson's "talk-back game" is an excellent way to bring the complications of appropriate tone to life. Describes three steps to incorporate Gibson's concept into the classroom. Notes that Gibson's concept considers the potential resistance of the reader. (SG)

Russo, Diana Saluri

2002-01-01

53

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

54

Hazard Patterns and Injury Prevention with Infant Walkers and Strollers.  

ERIC Educational Resources Information Center

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…

Wishon, Phillip M.; And Others

55

Walker with Harness for and Elderly Handicapped or Convalescent Person.  

National Technical Information Service (NTIS)

A walker for elderly, handicapped or convalescing people which includes a frame with a top rail member positioned above a user's center of gravity and a harness located inside the frame and suspended from the top rail member to provide stability and resis...

M. L. Wolfe

2005-01-01

56

Dandy-Walker malformation: prenatal diagnosis and prognosis  

Microsoft Academic Search

IntroductionThe difficulty in prognosticating the clinical and intellectual outcome of fetuses presenting with a Dandy-Walker malformation (DWM) comes from the great variety of cystic, median, and retrocerebellar malformations that probably have nothing in common and the variability of the definitions given to these lesions. In addition, many of these lesions can mimic each other. A correct diagnosis cannot be made

O. Klein; A. Pierre-Kahn; N. Boddaert; D. Parisot; F. Brunelle

2003-01-01

57

David Walker receives 2010 Harry H. Hess Medal  

Microsoft Academic Search

David Walker was awarded the 2010 Harry H. Hess Medal at the AGU Fall Meeting Honors Ceremony, held on 15 December 2010 in San Francisco, Calif. The medal is for ``outstanding achievements in research of the constitution and evolution of Earth and other planets.''

Carl B. Agee; David Walker

2011-01-01

58

3. GENERAL VIEW LOOKING NORTH FROM THE INTERSECTION OF WALKER ...  

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

3. GENERAL VIEW LOOKING NORTH FROM THE INTERSECTION OF WALKER AND LUMBER STREETS, SHOWING TWO HOUSES FRONTING ON LUMBER STREET, AND CENTRAL OF GEORGIA COACH AND PAINT SHOP IN BACKGROUND AT END OF STREET - Frogtown District, Bounded by Jones, I-66 Ramp, & West Boundary Streets, Savannah, Chatham County, GA

59

Klippel-Feil syndrome and Dandy-Walker malformation.  

PubMed

The Klippel-Feil deformity is a complex of osseous and visceral anomalies, which include low hairline, platybasia, fused cervical vertebrae with a short neck, and deafness. Associated central nervous system abnormalities include occipital cephalocele, Chiari I malformation, syrinx, microcephaly, and hydrocephalus. Herein, we report a case with Klippel-Feil syndrome and Dandy-Walker malformation. PMID:22303802

Karaman, A; Kahveci, H

2011-01-01

60

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

NASA Technical Reports Server (NTRS)

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.

1995-01-01

61

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

NASA Technical Reports Server (NTRS)

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.

1995-01-01

62

Efficient multigrid solver for the 3D random walker algorithm  

NASA Astrophysics Data System (ADS)

The random walker algorithm is a graph-based segmentation method that has become popular over the past few years. The basis of the algorithm is a large, sparsely occupied system of linear equations, whose size corresponds to the number of voxels in the image. To solve these systems, typically comprised of millions of equations, the computational performance of conventional numerical solution methods (e.g. Gauss-Seidel) is no longer satisfactory. An alternative method that has been described previously for solving 2D random walker problems is the geometrical multigrid method. In this paper, we present a geometrical multigrid approach for the 3D random walker problem. Our approach features an optimized calculation of the required Galerkin product and a robust smoothing using the ILU? method. To reach better convergence rates, the multigrid solver is used as a preconditioner for the conjugate gradient solver. We compared the performance of our new multigrid approach with the conjugate gradient solver on five MRI lung images with a resolution of 96 x 128 x 52 voxels. Initial results show an increasing in speed of up to four times, reducing the average computation time from six minutes to less than two minutes when using our proposed approach. Employing a multigrid solver for the random walker algorithm thus permits accurate interactive segmentation with fewer delays.

Wang, Xin; Heimann, Tobias; Naegel, Arne; Wittum, Gabriel; Meinzer, Hans-Peter

2009-02-01

63

Friedmann-Robertson-Walker-like cosmologies with spherical symmetry  

NASA Astrophysics Data System (ADS)

We reconsider the cosmological model discussed by Sung-Won Kim [Phys. Rev. D 53, 6889 (1996)] in the context of Friedmann-Robertson-Walker cosmologies with a traversable wormhole, where it is assumed that the matter content is divided into two parts: the cosmic part that depends on time only and the wormhole part that depends on space only. The cosmic part obeys the barotropic equation of state pc=??c. The complete analysis requires further care and reveals more interesting results than what was previously shown by the author. They can be readily applied to the evolution of a large class of cosmological models which are more general than Friedmann-Robertson-Walker models.

Cataldo, Mauricio; Aróstica, Fernanda; Bahamonde, Sebastian

2013-08-01

64

Teaching the evolution of behavior with SuperDuperWalker  

Microsoft Academic Search

Abstract. SuperDuperWalker is a software-based framework for experiments on the evolution of locomotion. It simulates the behavior of evolving agents in a 3D physical simulation environment and displays this behavior graphically in real time. A genetic algorithm controls the evolution of the agents. Students manipulate pa-rameters with a graphical user interface and plot outputs using standard utilities. The software supports

Lee Spector; Jon Klein; Kyle Harrington; Raymond Coppinger

2005-01-01

65

Teaching the evolution of behavior with SuperDuperWalker  

Microsoft Academic Search

SuperDuperWalker is a software-based framework for experiments on the evolution of locomotion. It simulates the behavior of evolving agents in a 3D physical simulation environment and displays this behavior graphically in real time. A genetic algorithm controls the evolution of the agents. Students manipulate pa- rameters with a graphical user interface and plot outputs using standard utilities. The software supports

Lee Spector; Jon Klein; Kyle Harrington; Raymond Coppinger

66

Neurocutaneous melanosis with associated Dandy-Walker complex  

Microsoft Academic Search

Case report  The authors report the case of a child with neurocutaneous melanosis associated with a Dandy-Walker complex. Magnetic resonance (MR) images showed shortened T1-weighted images in areas involving the amygdala, mesencephalon, rostral brain stem, and superior cerebellar surface compatible with melanin deposits. There was also partial agenesis of the cerebellar vermis with an enlarged fourth ventricle cyst along with a

Adrian Caceres; Humberto Trejos

2006-01-01

67

Terrain interaction with the quarter scale beam walker  

NASA Technical Reports Server (NTRS)

Frame walkers are a class of mobile robots that are robust and capable mobility platforms. Variations of the frame walker robot are in commercial use today. Komatsu Ltd. of Japan developed the Remotely Controlled Underwater Surveyor (ReCUS) and Normed Shipyards of France developed the Marine Robot (RM3). Both applications of the frame walker concept satisfied robotic mobility requirements that could not be met by a wheeled or tracked design. One vehicle design concept that falls within this class of mobile robots is the walking beam. A one-quarter scale prototype of the walking beam was built by Martin Marietta to evaluate the potential merits of utilizing the vehicle as a planetary rover. The initial phase of prototype rover testing was structured to evaluate the mobility performance aspects of the vehicle. Performance parameters such as vehicle power, speed, and attitude control were evaluated as a function of the environment in which the prototype vehicle was tested. Subsequent testing phases will address the integrated performance of the vehicle and a local navigation system.

Chun, Wendell H.; Price, S.; Spiessbach, A.

1990-01-01

68

Rice white stemborer Scirpophaga innotata (Walker) in southern Mindanao, Philippines. I. Supplantation of yellow stemborer S. incertulas (Walker) and pest status  

Microsoft Academic Search

The rice white stemborer (WSB) Scirpophaga innotata (Walker) supplanted the closely related rice yellow stemborer (YSB) S. incertulas (Walker) in irrigated, double-rice culture in both Koronadal, South Cotabato, Philippines and Java, Indonesia. In Java, WSB became a serious pest but not in Koronadal where damage levels remained unchanged. The species shift and subsequent outbreaks are seen as independent events. The

J. A. Litsinger; A. L. Alviola; C. G. Dela Cruz; B. L. Canapi; E. H. Batay-An III; A. T. Barrion

2006-01-01

69

Stability Margin Monitoring in Steering-Controlled Intelligent Walkers for the Elderly  

Microsoft Academic Search

This paper emphasizes the importance of assessing stability index for steering-controlled three-wheeled walkers. The paper describes a stability computation model that can be used to generate a reference input to the intelligent shared- control algorithm. The model can be used to evaluate the instantaneous stability margin of the walker-user system. This knowledge of the online stability of the walker will

Majd Alwan; Prabhu Jude Rajendran; Alexandre Ledoux; Cunjun Huang; Glenn Wasson; Pradip Sheth

70

Anisotropic evolution of 5D Friedmann-Robertson-Walker spacetime  

SciTech Connect

We examine the time evolution of the five-dimensional Einstein field equations subjected to a flat, anisotropic Robertson-Walker metric, where the 3D and higher-dimensional scale factors are allowed to dynamically evolve at different rates. By adopting equations of state relating the 3D and higher-dimensional pressures to the density, we obtain an exact expression relating the higher-dimensional scale factor to a function of the 3D scale factor. This relation allows us to write the Friedmann-Robertson-Walker field equations exclusively in terms of the 3D scale factor, thus yielding a set of 4D effective Friedmann-Robertson-Walker field equations. We examine the effective field equations in the general case and obtain an exact expression relating a function of the 3D scale factor to the time. This expression involves a hypergeometric function and cannot, in general, be inverted to yield an analytical expression for the 3D scale factor as a function of time. When the hypergeometric function is expanded for small and large arguments, we obtain a generalized treatment of the dynamical compactification scenario of Mohammedi [Phys. Rev. D 65, 104018 (2002)] and the 5D vacuum solution of Chodos and Detweiler [Phys. Rev. D 21, 2167 (1980)], respectively. By expanding the hypergeometric function near a branch point, we obtain the perturbative solution for the 3D scale factor in the small time regime. This solution exhibits accelerated expansion, which, remarkably, is independent of the value of the 4D equation of state parameter w. This early-time epoch of accelerated expansion arises naturally out of the anisotropic evolution of 5D spacetime when the pressure in the extra dimension is negative and offers a possible alternative to scalar field inflationary theory.

Middleton, Chad A. [Department of Physical and Environmental Sciences, Colorado Mesa University (formerly Mesa State College), Grand Junction, Colorado 81501 (United States); Stanley, Ethan [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)

2011-10-15

71

Dandy Walker malformation and hypertrophic cardiomyopathy. Unusual fatal association.  

PubMed

Dandy Walker malformation (DWM) is a rare congenital brain anomaly characterized by cystic dilation of the fourth ventricle and hypoplasia of the cerebellar vermis. Other extracranial anomalies can be associated, including cardiac defects. We report a rare patient with DWM associated with progressive heart failure secondary to hypertrophic cardiomyopathy. He was diagnosed at 2 months of age and died 5 months later. We conclude that hypertrophic cardiomyopathy can be associated with DWM with poor prognosis. A careful cardiac evaluation is needed in all infants with DWM for early recognition of such potentially serious associated cardiac malformations. PMID:21048653

Kurdi, Maher E; Chamsi-Pasha, Mohammed A; Baeesa, Saleh S; Jan, Mohammed M

2009-10-01

72

Finite perturbations on Friedmann-Robertson-Walker models. [Of cosmology  

SciTech Connect

By dimensional reduction of solutions of Einstein's equations in five-dimensional vacuum, two metrics are derived which can be interpreted as finite cylindrical perturbations of the solitonic type on a radiative Friedmann-Robertson-Walker (FRW) cosmological background. A linear perturbative analysis is performed and is compared with the exact nonlinear results. The metrics are transformed to perfect fluid solutions representing finite soliton perturbations on a FRW background with stiff matter. One metric contains density modes, and the other includes the coupling between density and radiative modes. 30 references.

Ibanez, J.; Verdaguer, E.

1986-07-01

73

Spatial and Lorentzian surfaces in Robertson-Walker space times  

NASA Astrophysics Data System (ADS)

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.

Chen, Bang-Yen; van der Veken, Joeri

2007-07-01

74

Monocoque structure for the SKITTER three-legged walker  

NASA Technical Reports Server (NTRS)

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.

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

75

A 'water walkers' exercise program for the elderly.  

PubMed Central

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.

Heyneman, C A; Premo, D E

1992-01-01

76

The Eastward Shift of the Walker Circulation in Global Warming  

NASA Astrophysics Data System (ADS)

In this talk we discuss the global warming response of the Walker Circulation and the other zonal circulation cells (represented by the zonal stream function) in a CMIP5 multi model ensemble (MMEns) in the RCP4.5 scenario. The changes in the mean state are presented as well as the changes in the modes of variability. The mean zonal circulation weakens nearly everywhere along the equator, but in the Pacific the Walker cell also shifts eastwards. These changes in the mean circulation are very similar to the leading mode of interannual variability in the tropical zonal circulation cells, which is dominated by ENSO variability. During an El Nino event the mass transport weakens and the rising branch over the Maritime Continent shifts to the east in comparison to neutral conditions. A large part of the global warming trend (66%) can be explained by a long term trend in this interannual variability pattern, i.e. a shift towards more El Nino like conditions in the MMEns in global warming. Further is in interannual variability the El Nino pattern of zonal stream function more in the east than the La Nina pattern, thus representing a spatial non-linearity. Consistent with this non-linearity we find a shift to the east of the dominant mode of variability of zonal stream function in global warming. The MMEns of CMIP3 (22 models) shows in all aspects very similar results to the CMIP5 MMEns (36 models), which underlines the robustness of these results.

Bayr, T.; Dommenget, D.; Martin, T.

2013-12-01

77

A.R.P. Walker Lecture. Food and the gut.  

PubMed

A.R.P. Walker pioneered the research into the association between food, gut function and disease patterns in southern Africa. His attention to ways in which dietary differences can explain geographical differences in disease patterns has led to the realisation that civilisation and modern food technology can exert a strong influence on dietary practices, gut function and disease tendencies. Recognition that South African blacks have a very low incidence of colonic problems such as diverticulitis, adenomatous polyps and carcinoma drew attention to the possibility that the traditional African diet, with a high fibre content, may maintain colonic health and prevent disease in old age. This review explores some of the mechanisms that may account for these differences and also examines ways in which malnutrition alters gut function. To quote Walker's conclusions: 'There is a need, indeed a duty, for writers on nutrition to devote a portion of their space to the nutritional lessons to be learned from the past, from war-time experiences and from present day Third-World populations.' PMID:7778001

O'Keefe, S J

1995-04-01

78

Casimir effect for curved boundaries in Robertson-Walker spacetime  

NASA Astrophysics Data System (ADS)

Vacuum expectation values of the energy-momentum tensor and the Casimir forces are evaluated for scalar and electromagnetic fields in the geometry of two curved boundaries on the background of the Robertson-Walker spacetime with negative spatial curvature. The boundaries under consideration are conformal images of the flat boundaries in Rindler spacetime. Robin boundary conditions are imposed in the case of the scalar field and perfect conductor boundary conditions are assumed for the electromagnetic field. We use the conformal relation between the Robertson-Walker and Rindler spacetimes and the corresponding results for two parallel plates moving with uniform proper acceleration through the Fulling-Rindler vacuum. For the general scale factor the vacuum energy-momentum tensor is decomposed into the boundary-free and boundary-induced parts. The latter is non-diagonal. The Casimir forces are directed along the normals to the boundaries. For the Dirichlet and Neumann scalars and for the electromagnetic field these forces are attractive for all separations.

Saharian, A. A.; Setare, M. R.

2010-11-01

79

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

USGS Publications Warehouse

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.

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

2009-01-01

80

A new dynamometer walker system for the measurement of handle reaction vector (HRV)  

Microsoft Academic Search

The handle reaction vector (HRV) is commonly prescribed as an effective index for evaluating paraplegic walking efficiency assisted by functional electrical stimulation (FES). But up to now relevant studies on HRV have been limited because its direct measurement on walker handle is rather inconvenient. This paper reports the design of a new dynamometer walker to indirectly measure the HRV, which

Dong Ming; Baikun Wan; Yong Hu; Yizhong Wang

2005-01-01

81

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

ERIC Educational Resources Information Center

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…

Koman, Rita

2000-01-01

82

Cytokine gene expression in Walker 256: A comparison of variants A (aggressive) and AR (regressive)  

Microsoft Academic Search

Two variants of this Walker 256 tumor have been previously reported as Walker 256 A and variant AR. The variant A has more aggressive property than variant AR and can induce systemic effects such as anorexia, sodium and water retention, followed by weight loss and death. The mechanisms involved in enhancing tumor regression and progression in this model are still

Ana Paula De Almeida Salles Perroud; Rika Ashimine; Glaucia Monteiro De Castro; Fernando Guimarães; Karla Priscila Vieira; Conceição Aparecida Vilella; Tereza Cristina Samico Cavalcanti; Ricardo De Lima Zollner

2006-01-01

83

Structural properties of a low Earth orbit satellite constellation - the Walker delta network  

Microsoft Academic Search

The Walker (1984) delta satellite constellation appears to be practical to serve as a low Earth orbit satellite network to provide world-wide networking. The structural properties of the Walker delta network, including diameter, mean message traversal, traffic density, and network saturation conditions are investigated and presented. Three different traffic patterns are used in this study. It has been found that

Chia-Jiu Wang

1993-01-01

84

Shared Navigational Control and User Intent Detection in an Intelligent Walker  

Microsoft Academic Search

This paper describes the navigational control scheme used in the CO-Operative Locomotion Aide (COOL Aide), an intelligent walker designed to assist the elderly or the disabled with normal, and routine walking tasks. Navigation is achieved through a shared control architecture that recognizes the goals of both the human user and the walker. The control system is based on a synthesis

Cunjun Huang; Glenn Wasson; Majd Alwan; Pradip Sheth; Alexandre Ledoux

85

Effects of High Levels of Total Dissolved Solids in Walker Lake, Nevada, on Survival and Growth of Lahontan Cutthroat Trout  

Microsoft Academic Search

Walker Lake, Nevada, is an endorheic terminal lake experiencing significant increases in total dissolved solids (TDS) because of culturally derived reductions in inflow and continued evaporative water losses. Maintenance of the Walker Lake fishery for native Lahontan cutthroat trout Oncorhynchus clarki henshawi requires artificial propagation because fish no longer have access to suitable spawning sites upstream in the Walker River.

Bobette R. Dickerson; Gary L. Vinyard

1999-01-01

86

Path tracking control considering center of gravity shift and load change for an omni-directional walker  

Microsoft Academic Search

Walking is a vital exercise that is very important for health and everyday life. In the authors' previous studies, an omni-directional walker was developed for walking rehabilitation. Walking training programs are stored in the walker so that rehabilitation can be carried out without a physical therapist. However, the walker sometimes strays from the predefined path due to a center of

Renpeng Tan; Shuoyu Wang; Yinlai Jiang; Kenji Ishida; Masanori Nagano

2010-01-01

87

A case study on Walker-Warburg syndrome.  

PubMed

Walker-Warburg syndrome (WWS) is a rare, lethal genetic disease associated with a cobblestone-type lissencephaly, eye abnormalities, and a type of muscular dystrophy. There is a wide spectrum of brain and eye defects associated with this diagnosis; therefore, this diagnosis may not initially be considered. This diagnosis is especially difficult for families because there is no treatment available and management of the condition is supportive only. Parents of an infant with WWS need to be shown support and empathy while they are dealing with the sorrow of a terminal illness. Use of a nursing model, "Middle range theory of chronic sorrow," will be instrumental in assisting staff as they care for the patient and the patient's family. They also need to be guided toward receiving genetic counseling to weigh their options for future family planning as the risk of another WWS pregnancy is 25%. PMID:20150777

Kerr, Stephanie L

2010-02-01

88

Clustering Determines Who Survives for Competing Brownian and Lévy Walkers  

NASA Astrophysics Data System (ADS)

The competition between two ecologically similar species that use the same resources and differ from each other only in the type of spatial motion they undergo is studied. The latter is assumed to be described either by Brownian motion or Lévy flights. Competition is taken into account by assuming that individuals reproduce in a density-dependent fashion. It is observed that no influence of the type of motion occurs when the two species are in a well-mixed unstructured state. However, as soon as the species develop spatial clustering, the one forming more concentrated clusters gets a competitive advantage and eliminates the other. A similar competitive advantage would occur between walkers of the same type but with different diffusivities if this leads also to different clustering. The coexistence of both species is also possible under certain conditions.

Heinsalu, Els; Hernández-Garcia, Emilio; López, Cristóbal

2013-06-01

89

The Enigmatic Young Object: Walker 90/V590 Mon  

NASA Astrophysics Data System (ADS)

Just about 20 arcminutes north-west of the Cone Nebula near the center of the open cluster NGC 2264, resides one of the most intriguing objects in this region: Walker 90 (V590 Mon, LkH? 25, NGC 2264-Vas62, IRAS 06379+0950). This object, according to its spectral type (B8pe) is at least 3 magnitudes too faint in V ( ~ 12.7) for the cluster distance, but it shows the classical signs of a young pre-main sequence object such as highly variable H? emission, Mg II emission, IR excess, and some optical variability. According to star formation processes, this object is expected to clear its primordial surroundings by becoming optically brighter, by weakening its IR excess colors and by decreasing some line emissions. This process was thought to have occurred when Bhatt & Sagar (1992, A&AS, 92, 473), from observations taken in 1989, announced that this object was 3 magnitudes brighter at V=9.7. Unfortunately, this was demonstrated to be a false alarm. Our observations for the last decade show small variabilities (around V ~ 12.7) with some brightening trends. We present a collection of archival and original data on Walker 90, ranging from optical photometry, to ultraviolet spectroscopic data. This object, unlike many other more evolved pre-main sequence objects, is either in the late stages of clearing its embryonic material or is directly behind a dark molecular cloud and is being affected by dense selective extinction. In either case, several other observational properties make this object very unique and enigmatic.

Perez, M. R.; van den Ancker, M. E.; Joner, M. D.; McCollum, B.

2002-12-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

91

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

PubMed

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

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

2007-06-29

92

Strain partitioning in the northern Walker Lane, western Nevada and northeastern California  

Microsoft Academic Search

Paleomagnetic studies constrain both the kinematics and the timing of Neogene intracontinental strain in the Walker Lane of northwestern Nevada–northeastern California. The northwest-trending Walker Lane is a zone of complex faulting and dextral offset along the boundary between the Sierra Nevada and the Basin and Range. Here, an extensive Tertiary volcanic section provides a paleomagnetic test for vertical-axis rotation. The

Patricia H Cashman; Sheryl A Fontaine

2000-01-01

93

The Inhibition of Ga Cl3 on the rat bones invaded by tumor cell Walker 256  

Microsoft Academic Search

Objective To observe the inhibition of GaCl3 on the rat bones invaded by tumor cell Walker256. Metho ds We injected Walker256 into the upper one2third medial tibia of the right posterior limb and made the rat model of bone invaded by the tumor cells , and then observed X2ray , biochemical and pathological indicators . Re sult s GaCl3 inhibited

Du Heng; Cui Gang; Zhang Zengtie; Zhang Fujun; Geng Dong; Zhai Lianbang; Liu Miao

94

Passive derivation of basic walker-assisted gait characteristics from measured forces and moments  

Microsoft Academic Search

This work describes a method that passively assesses basic walker-assisted gait characteristic, including heel strikes, toe-off events, as well as stride time, double support and right & left single support phases using only force-moment measurements from the walker's handles. The passively derived gait characteristics were validated against motion capture gait analysis and showed good correlations. This research is part of

M. Alwan; G. Wasson; P. Sheth; A. Ledoux; C. Huang

2004-01-01

95

Virtual Slope Control of a Forward Dynamic Bipedal Walker  

PubMed Central

Active joint torques are the primary source of power and control in dynamic walking motion. However the amplitude, rate, timing and phasic behavior of the joint torques necessary to achieve a natural and stable performance are difficult to establish. The goal of this study was to demonstrate the feasibility and stable behavior of an actively controlled bipedal walking simulation wherein the natural system dynamics were preserved by an active, nonlinear, state-feedback controller patterned after passive downhill walking. A two degree-of-freedom, forward-dynamic simulation was implemented with active joint torques applied at the hip joints and stance leg ankle. Kinematic trajectories produced by the active walker were similar to passive dynamic walking with active joint torques influenced by prescribed walking velocity. The control resulted in stable steady-state gait patterns, i.e. eigenvalue magnitudes of the stride function were less than one. The controller coefficient analogous to the virtual slope was modified to successfully control average walking velocity. Furture developments are necessary to expand the range of walking velocities.

Russell, S.; Granata, K. P.; Sheth, P.

2006-01-01

96

Field performance of the Walker Branch throughfall displacement experiment  

SciTech Connect

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.

Hanson, P.J.; Todd, D.E.; Edwards, N.T.; Huston, M.A. [Oak Ridge National Lab., TN (United States). Environmental Sciences Div.

1994-10-06

97

Sandpile models and random walkers on finite lattices  

NASA Astrophysics Data System (ADS)

Abelian sandpile models, both deterministic, such as the Bak, Tang, Wiesenfeld (BTW) model [P. Bak, C. Tang, and K. Wiesenfeld, Phys. Rev. Lett. 59, 381 (1987)], and stochastic, such as the Manna model [S.S. Manna, J. Phys. A 24, L363 (1991)], are studied on finite square lattices with open boundaries. The avalanche size distribution PL(n) is calculated for a range of system sizes, L. The first few moments of this distribution are evaluated numerically and their dependence on the system size is examined. The sandpile models are conservative in the sense that grains are conserved in the bulk and can leave the system only through the boundaries. It is shown that the conservation law provides an interesting connection between the sandpile models and random-walk models. Using this connection, it is shown that the average avalanche sizes L for the BTW and Manna models are equal to each other, and both are equal to the average path length of a random walker starting from a random initial site on the same lattice of size L. This is in spite of the fact that the sandpile models with deterministic (BTW) and stochastic (Manna) toppling rules exhibit different critical exponents, indicating that they belong to different universality classes.

Shilo, Yehiel; Biham, Ofer

2003-06-01

98

A new walker with upper trunk suspension system for severely disabled patients.  

PubMed

We have recently designed a new type of walker for those severely disabled patients who cannot walk with commonly used medical walkers. A drawing and the description of this new walker is reported in order to permit the worldwide companies as well as artisans to develop and produce it for the people affected from severe motor problems. This walker supposes the patient wearing either a modified climbing harness or equipped clothes and being suspended to the walking frame. It consists in two series of bands suspending the patient from the frame; the upper one suspends him for the upper part of his trunk, the lower one by his pelvis. This walker is suggested for patients belonging to three principal groups: (1) Persons who have no trunk control (e.g.: patients affected by severe stroke or ataxias). (2) Persons whose walk is allowed only if they achieve a significant reduction (up to 30-40%) of the their body weight charging on trunk, spine, and lower limbs. (3) Persons who need a differentiated reduction of the body weight either among anterior and posterior side or among their right and left part of the body (hemiparesis, Parkinson disease, scoliosis, kyphosis). Creating this walker is easy; producing costs are low; there are no maintenance costs. PMID:24142620

Scoppetta, C; Scoppetta, M

2013-10-01

99

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

USGS Publications Warehouse

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

Lopes, Thomas J.; Allander, Kip K.

2009-01-01

100

Einstein energy associated with the Friedmann-Robertson-Walker metric  

NASA Astrophysics Data System (ADS)

Following Einstein’s definition of Lagrangian density and gravitational field energy density (Einstein in Ann Phys Lpz 49:806, 1916, Einstein in Phys Z 19:115, 1918, Pauli in Theory of Relativity, B.I. Publications, Mumbai, 1963), Tolman derived a general formula for the total matter plus gravitational field energy ( P 0) of an arbitrary system (Tolman in Phys Rev 35:875, 1930, Tolman in Relativity, Thermodynamics & Cosmology, Clarendon Press, Oxford, 1962, Xulu in hep-th/0308070, 2003). For a static isolated system, in quasi-Cartesian coordinates, this formula leads to the well known result {P_0 = int sqrt{-g} (T_0^0 - T_1^1 - T_2^2 - T_3^3) d^3 x,} where g is the determinant of the metric tensor and {T^a_b} is the energy momentum tensor of the matter. Though in the literature, this is known as “Tolman Mass”, it must be realized that this is essentially “Einstein Mass” because the underlying pseudo-tensor here is due to Einstein. In fact, Landau-Lifshitz obtained the same expression for the “inertial mass” of a static isolated system without using any pseudo-tensor at all and which points to physical significance and correctness of Einstein Mass (Landau, Lifshitz in The Classical Theory of Fields, Pergamon Press, Oxford, 1962)! For the first time we apply this general formula to find an expression for P 0 for the Friedmann-Robertson-Walker (FRW) metric by using the same quasi-Cartesian basis. As we analyze this new result, it transpires that, physically, a spatially flat model having no cosmological constant is preferred. Eventually, it is seen that conservation of P 0 is honoured only in the static limit.

Mitra, Abhas

2010-03-01

101

Pacific Walker Circulation variability in coupled and uncoupled climate models  

NASA Astrophysics Data System (ADS)

There is still considerable uncertainty concerning twentieth century trends in the Pacific Walker Circulation (PWC). In this paper, observational datasets, coupled (CMIP5) and uncoupled (AGCM) model simulations, and additional numerical sensitivity experiments are analyzed to investigate twentieth century changes in the PWC and their physical mechanisms. The PWC weakens over the century in the CMIP5 simulations, but strengthens in the AGCM simulations and also in the observational twentieth century reanalysis (20CR) dataset. It is argued that the weakening in the CMIP5 simulations is not a consequence of a reduced global convective mass flux expected from simple considerations of the global hydrological response to global warming, but is rather due to a weakening of the zonal equatorial Pacific sea surface temperature (SST) gradient. Further clarification is provided by additional uncoupled atmospheric general circulation model simulations in which the ENSO-unrelated and ENSO-related portions of the observed SST changes are prescribed as lower boundary conditions. Both sets of SST forcing fields have a global warming trend, and both sets of simulations produce a weakening of the global convective mass flux. However, consistent with the strong role of the zonal SST gradient, the PWC strengthens in the simulations with the ENSO-unrelated SST forcing, which has a strengthening zonal SST gradient, despite the weakening of the global convective mass flux. Overall, our results suggest that the PWC strengthened during twentieth century global warming, but also that this strengthening was partly masked by a weakening trend associated with ENSO-related PWC variability.

Sandeep, S.; Stordal, Frode; Sardeshmukh, Prashant D.; Compo, Gilbert P.

2014-04-01

102

Electro-actuated hydrogel walkers with dual responsive legs.  

PubMed

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

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

2014-03-01

103

Therapeutic effects of all trans-retinoitc acid combined with transarterial chemoembolization on Walker256 hepatoma in rats  

Microsoft Academic Search

Summary  In order to investigate the inhibitory effects of all trans-retinoitc acid (ATRA) on differentiation and apoptosis of Walker-256\\u000a hepatocellular carcinoma cells and the therapeutic effects of ATRA combined with transarterial chemoembolization (TACE) on\\u000a rat Walker-256 transplanted hepatocarcinoma, Walker-256 hepatocarcinoma cell lines were treated with ATRA at different concentrations.\\u000a After culture for 48 h, the inhibitory rate of cell proliferation was

Jianlin Fang; Chuansheng Zheng; Hongfang Tao; Hui Zhao; Jianzhuang Ren; Gansheng Feng

2010-01-01

104

X-4 with Pilot Joe Walker, Preflight Briefing  

NASA Technical Reports Server (NTRS)

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.

1952-01-01

105

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

USGS Publications Warehouse

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

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

1991-01-01

106

Fraction of uninfected walkers in the one-dimensional Potts model  

NASA Astrophysics Data System (ADS)

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

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

2002-05-01

107

Viscous Cosmology and Thermodynamics of Apparent Horizon in Modified Friedman-Robertson-Walkers Universe  

NASA Astrophysics Data System (ADS)

In this paper, we write modified Friedman-Robertson-Walkers (FRW) equation in the form of first law of thermodynamics at the apparent horizon. We consider the universe filled with the viscous fluid. Here we employ the general expression of temperature gravity and entropy at the apparent horizon of FRW universe and obtain the generalized first law of thermodynamics at the special condition for the modified FRW equation. The generalized first law of thermodynamics help us to arrange the ? 1, ? 2, ? 1 and ? 2 in modified Friedman-Robertson-Walkers equation.

Sadeghi, J.; Naji, J.; Vaez, H.; Khanpour, B.

2014-04-01

108

What controls the strength of the Walker circulation? The role of spatial variations in cloud albedo  

NASA Astrophysics Data System (ADS)

The mean Walker circulation, and the east-west gradient of sea surface temperature (SST) along the equator, are two central features of the tropical ocean-atmosphere system. Tightly coupled, they define background climate conditions in the tropics, including the zonal tilt of the ocean thermocline and equatorial upwelling. In the Pacific, the presence of the Walker cell also supports the El Niño-Southern Oscillation phenomenon (ENSO). What determines the strength of the Walker circulation and the east-west SST gradient in the coupled ocean-atmosphere system is therefore a fundamental question within climate dynamics. Using a suite of simulations conducted with a comprehensive coupled model (CESM), we demonstrate how meridional variations in cloud albedo can set this SST gradient and control the Walker circulation. Specifically, by modulating shortwave radiation able to reach the ocean surface and hence the net shortwave flux at the top of the atmosphere, spatial variations in albedo modify the ocean poleward heat transport from low to mid-latitudes. These changes in the heat transport directly correlate with changes in the upper-ocean heat content in the tropics, the temperature of the equatorial cold tongue, and the zonal SST gradient along the equator. We show that whereas tropical cloud albedo controls the maximum temperatures over the western Pacific warm pool, extra-tropical albedo controls SSTs in the eastern Pacific. Consequently, it is the meridional difference in cloud albedo that controls the equatorial SST gradient and the Walker circulation. Our results can be summarized using the gradient of cloud albedo between the equator and mid-latitudes (??) as the relevant parameter. When we vary ?? from 0.1 to -0.1, the east-west SST contrast in the Pacific reduces from 5°C to below 0.5°C and the Walker circulation nearly collapses. These results represent a potential mechanism for long-term changes in the Walker circulation and are directly relevant to past climates, especially the Pliocene epoch when it is believed that the Walker cell was significantly weaker than at present.

Burls, N.; Fedorov, A. V.

2012-12-01

109

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

NASA Technical Reports Server (NTRS)

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.

1962-01-01

110

Baby walker safety - baby's minder or parent's problem? A qualitative analysis of clients' knowledge, attitudes and practices regarding baby walker use  

Microsoft Academic Search

Objective To investigate the range of knowledge, attitudes and practices of parents regarding baby walkers.Design A qualitative study using a focus group approach.Setting Three focus groups were held in community mother and toddler drop-in centres, and one in a hospital antenatal clinic.Methods Four focus groups were held over a two-month period in 2000. Parents from areas with differing levels of

Rhydian Hapgood; Amanda Woods; Jane Dyas; Elaine Bentley; Denise Kendrick

2003-01-01

111

Obituary: Alastair Graham Walker Cameron, 1925-2005  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

112

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

ERIC Educational Resources Information Center

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…

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

2004-01-01

113

Use of the charcot restraint orthotic walker in treatment of neuropathic foot ulcers: a case series.  

PubMed

Although the total contact cast is the criterion standard for the pressure redistribution of challenging foot ulcers, in practice it is not often feasible. The following is a case series that demonstrates an encouraging possibility for the Charcot restraint orthotic walker as a device to be used in more challenging forefoot ulcers. PMID:24253211

Keast, David H; Vair, Audra H

2013-12-01

114

Transplantation of Local Nets and Geometric Modular Action on Robertson-Walker Space-Times  

Microsoft Academic Search

A novel method of transplanting algebras of observables from de Sitter space to a large class of Robertson-Walker space-times is exhibited. It allows one to establish the existence of an abundance of local nets on these spaces which comply with a recently proposed condition of geometric modular action. The corresponding modular symmetry groups appearing in these examples also satisfy a

Detlev Buchholz; Jens Mund; Stephen J. Summers

2000-01-01

115

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

Microsoft Academic Search

Maxwell and Dirac fields in Friedmann Robertson Walker (FRW) spacetime are investigated using the Newman Penrose method. The variables are all separable, with the angular dependence given by spin-weighted spherical harmonics. All the radial parts reduce to the barrier penetration problem, with mostly repulsive potentials representing the centrifugal energies. Both the helicity states of the photon field see the same

U. Khanal

2006-01-01

116

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

ERIC Educational Resources Information Center

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…

SHW Group, Inc., Dallas, TX.

117

Utilizing a Computational Model for the Design of a Passive Dynamic Walker  

Microsoft Academic Search

Recent interest in using passive dynamic walkers (PDWs) for gait rehabilitation studies has presented a need for a robust, easily built mechanism. Unfortunately, these passive robots are hypersensitive to many variables outside of the usual design considerations that are studied when constructing them. By accentuating previous failures instead of suppressing them, this thesis presents a number of problematic situations commonly

Craig Alan Honeycutt

2011-01-01

118

An Open Letter to Suzanne deCastell and Tom Walker.  

ERIC Educational Resources Information Center

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)

Assinck, Beverly Belvin

1993-01-01

119

Effects of the Mean Walker Circulations on the Zonal Variability of Tropical CISK Waves  

Microsoft Academic Search

An idealized zonally asymmetric mean state in the Tropics is used to investigate the effects of atmospheric mean Walker circulations and sea surface temperatures on the zonal variability of tropical waves with positive- only wave-CISK heating.First, the effects of the zonally symmetric vertical and meridional shears of the mean zonal flow are investigated with different vertical profiles of convective heating

Weixing Shen; Marvin A. Geller

1998-01-01

120

Coinfection with Multiple Tick-Borne Pathogens in a Walker Hound Kennel in North Carolina  

Microsoft Academic Search

Both dogs and humans can be coinfected with various Ehrlichia, Bartonella, Rickettsia, and Babesia species. We investigated a kennel of sick Walker Hounds and their owners in southeastern North Carolina for evidence of tick-borne infections and associated risk factors. A high degree of coinfection was documented in the dog population. Of the 27 dogs, 26 were seroreactive to an Ehrlichia

S. K. KORDICK; E. B. BREITSCHWERDT; B. C. HEGARTY; K. L. SOUTHWICK; C. M. COLITZ; S. I. HANCOCK; J. M. BRADLEY; R. RUMBOUGH; J. T. MCPHERSON

1999-01-01

121

Detection of the relevant type of locomotion in infancy: Crawlers versus walkers  

Microsoft Academic Search

Human infants show a preference for individuals who are similar to them. Using point-light displays of human walkers and crawlers as stimuli, we examined whether infants’ preference for the motions of crawling and walking changes between, before, and after the onset of bipedal walking. The results show that crawling and walking infants prefer the types of locomotion that are similar

Wakako Sanefuji; Hidehiro Ohgami; Kazuhide Hashiya

2008-01-01

122

Photothermally modulated spatially resolved FMR detection of Walker modes in yttrium iron garnet spheres  

Microsoft Academic Search

The photothermally modulated (PM) ferromagnetic resonance (FMR) combines the high sensitivity of conventional FMR and spatial resolution. This technique has been applied to a single-crystalline yttrium iron garnet (YIG) sphere with a diameter of 2 mm. For the first time, the spatial variation of the high-frequency magnetization patterns known as Walker modes were visualized and it is thus shown that

F. Rodelsperger; F. Schreiber; H. Benner; J. Pelzl

1994-01-01

123

Walker Branch Watershed surveying and mapping including a guide to coordinate transformation procedures. 1989.  

National Technical Information Service (NTIS)

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 wat...

S. Timmins J. Chason

1991-01-01

124

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

ERIC Educational Resources Information Center

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.

Sherblom, Stephen A.

2009-01-01

125

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

Microsoft Academic Search

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

M. C. Reheis; J. S. Noller

1987-01-01

126

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

ERIC Educational Resources Information Center

"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…

Bahr, Kathy

2010-01-01

127

Dandy-Walker syndrome: different modalities of treatment and outcome in 42 cases  

Microsoft Academic Search

Objects: Forty-two patients with Dandy-Walker syndrome who were treated with different surgical modalities over a period of 8 years, from 1988 to 1996, at the Sanjay Gandhi Post Graduate Institute of Medical Sciences were reviewed in the present study. Methods: All the patients presented with hydrocephalus at the time of diagnosis. Association of other CNS anomalies was detected in 9

Raj Kumar; Manoj Kumar Jain; Devendra Kumar Chhabra

2001-01-01

128

Dandy-Walker syndrome: posterior fossa craniectomy and cyst fenestration after several shunt revisions  

Microsoft Academic Search

Ventriculoperitoneal or cyst-peritoneal shunts are the usual treatment for children with Dandy-Walker syndrome. A combined ventricular and cyst shunt is often necessary and, in some cases, multiple revisions have to be done. Two patients with this syndrome were treated with posterior fossa exploration and cyst fenestration after several shunt revisions. The procedure was well tolerated with good results in both

G. M. Almeida; H. Matushita; L. C. Mattosinho-França; M. K. Shibata

1990-01-01

129

Revised flood hazard data on west Chickamauga Creek in the vicinity of Walker County, Georgia  

SciTech Connect

This report provides flood hazard information for the portion of West Chickamauga Creek (stream mile 20.05 to mile 24.86) which lies within the unincorporated area of Walker County, Georgia. Local officials may wish to use the maps and profiles contained in this report to supplement those prepared by FEMA in carrying out their floodplain management program activities.

Not Available

1982-12-01

130

Walker Branch Watershed element cycling studies: collection and analysis of wetfall for trace elements and sulfate  

Microsoft Academic Search

A precipitation sampling network designed specifically to optimize sample collection and handling for trace analysis was established at Walker Branch Watershed (WBW), Tennessee, to measure the atmospheric input of trace elements. The network consists of 6 rain activated wetfall collectors of the AEC-HASL design which have been modified in order to minimize trace element contamination. Wetfall has been collected through

S. E. Lindberg; R. R. Turner; N. M. Ferguson; D. Matt

1977-01-01

131

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

NASA Technical Reports Server (NTRS)

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.

1989-01-01

132

Profound skeletal muscle depletion of ?-dystroglycan in Walker-Warburg syndrome  

Microsoft Academic Search

Walker-Warburg syndrome (WWS) is an autosomal recessive disorder characterized by the combined involvement of the central nervous and skeletal muscle systems. Although the molecular basis of WWS remains unknown, defects in the muscle fibre basal lamina are characteristic of other forms of congenital muscular dystrophy (CMD). In agreement with this, some forms of CMD, due to glycosyltransferase defects, display a

Cecilia Jiménez-Mallebrera; Silvia Torelli; Susan C Brown; Lucy Feng; Martin Brockington; Caroline A Sewry; Daniel Beltrán-Valero De Bernabé; Francesco Muntoni

2003-01-01

133

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

PubMed

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

John, Jomol Sara; Vanitha, R

2013-09-01

134

Quantitative Assessment of Brainstem Development in Joubert Syndrome and Dandy-Walker Syndrome  

Microsoft Academic Search

Key features of Joubert syndrome include developmental delay, hypotonia, hyperpnea and apnea, oculomotor apraxia, and the presence of the molar tooth sign on axial imaging through the brainstem isthmus—the junction of the pons and mesencephalon. Interestingly, 1 in 10 patients with Joubert syndrome has abnormal cerebrospinal fluid collections misdiagnosed as Dandy-Walker variants. Because of important differences in patient management, genetic

Bernard L. Maria; Alilreza Bozorgmanesh; Kimberly N. Kimmel; Douglas Theriaque; Ronald G. Quisling

2001-01-01

135

GPS constraints on shear accommodation in the northern Walker Lane, western Nevada, USA  

NASA Astrophysics Data System (ADS)

The Walker Lane is a zone of active intracontinental transtension that accommodates approximately 10 mm/yr of right-lateral deformation, up to 20-25% of Pacific-North America relative plate motion. Between Walker Lake and Lake Tahoe, the Walker Lane lacks optimally oriented strike-slip faults to accommodate northwest-directed dextral shear. In this region Quaternary deformation appears to be concentrated in a northwest-trending series of north-striking, normal fault-bounded basins. To address the question of how shear is transferred through this portion of the Walker Lane, we combine GPS data from the University of Nevada, Reno’s semi-continuous MAGNET GPS network with observations from EarthScope’s Plate Boundary Observatory to present a new velocity field for the Walker Lane with an average station spacing of 20 km. Measurements in MAGNET (http://geodesy.unr.edu/networks) began in January 2004 and now provide time series of up to 6 years for the longest running sites and >3 years for all sites. Together with recent improvements in GPS data processing models using the GIPSY-OASIS II software, this allows us to estimate rates with uncertainty well below 1 mm/yr. These recent improvements include the use of reprocessed GPS orbits from the IGS Analysis Center at JPL. Our GPS processing now includes satellite and station antenna calibrations, random-walk tropospheric zenith delay and gradients using the GMF mapping function, second-order ionospheric corrections, global-scale ambiguity resolution using our custom Ambizap software, and our custom Great Basin spatially-filtered reference frame. The velocity solution shows a smooth and continuous increase in shear across the Walker Lane in addition to NW-SE directed extension. We use a block model driven by GPS velocities to estimate the role that vertical axis rotation of fault-bounded blocks and slip on basin-bounding faults play in shear accommodation. The block model also allows us to incorporate published geologic fault slip rates and thus test the compatibility of the available geodetic and geologic datasets for the northern Walker Lane.

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

2009-12-01

136

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

PubMed

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

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

137

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

PubMed

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

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

2006-12-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

139

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

NASA Astrophysics Data System (ADS)

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

Pier, Jeffrey R.; Mason, Brian

2005-12-01

140

Caroline Pryce Walker Conquer Childhood Cancer Reauthorization Act (H.R. 2607/S. 1251; 113th Congress)  

Cancer.gov

This bill is a reauthorization of the original Carolyn Pryce Walker Conquer Childhood Cancer Act that was passed unanimously in the House and the Senate in 2008 (named in honor of former Representative Deborah Pryce's daughter, Caroline). The bill

141

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

PubMed Central

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

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

2013-01-01

142

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

ERIC Educational Resources Information Center

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…

Huber, Germaine W.

2009-01-01

143

ISOLATION AND PURIFICATION OF RP2-L, A NUCLEAR PROTEIN FRACTION OF THE WALKER 256 CARCINOSARCOMA  

Microsoft Academic Search

One hour after the injection of 5 mu c of L-lysine-U-C¹⁴ into ; each of a group of rats bearing the Walker 256 carcinosarcoma, the acid-soluble ; proteins were extracted from nuclear preparations of the tumor. The proteins of ; these extracts were chromatographed on carboxymethylcellulose, with formic acid ; as the eluting agent. Rechromatography of 150 mg of RP2-L¹

H. Busch; L. S. Hnilica; S. Chien; J. R. Davis; C. W. Taylor

1962-01-01

144

Can intermittent long-range jumps of a random walker compensate for lethargy?  

NASA Astrophysics Data System (ADS)

We study the dynamics of a lazy random walker who is inactive for extended times and tries to make up for her laziness with very large jumps. She remains in a condition of rest for a time ? derived from a waiting-time distribution \\psi (\\tau )\\propto 1/\\tau ^{\\mu _{W}}, with ?W < 2, thereby making jumps only from time to time from a position x to a position x' of a one-dimensional path. However, when the random walker jumps, she moves by quantities l = |x - x'| derived randomly from a distribution \\pi (l)\\propto 1/l^{\\mu _{\\xi }}, with ?? > 1. The most convenient choice to make up for the random walker laziness would be to select ?? < 3, which in the ordinary case ?W > 2 would produce Lévy flights with scaling ? = 1/(?? - 1) and consequently super-diffusion. According to the Sparre Andersen theorem, the distribution density of the first times to go from xA to xB > xA has the inverse power law form f(t)\\propto \\frac{1}{t^{\\mu _{_{FPT}}}} with ?FPT = ?SA = 1.5. We find the surprising result that there exists a region of the phase space (??, ?W) with ?W < 2, where ?FPT > ?SA and the lazy walker compensates for her laziness. There also exists an extended region breaking the Sparre Andersen theorem, where the lazy runner cannot compensate for her laziness. We make conjectures concerning the possible relevance of this mathematical prediction, supported by numerical calculations, for the problem of animal foraging.

Bologna, Mauro; Ahat, Yasin; West, Bruce J.; Grigolini, Paolo

2011-04-01

145

Approximate KMS States for Scalar and Spinor Fields in Friedmann–Robertson–Walker Spacetimes  

Microsoft Academic Search

We construct and discuss Hadamard states for both scalar and Dirac spinor fields in a large class of spatially flat Friedmann–Robertson–Walker\\u000a spacetimes characterised by an initial phase either of exponential or of power-law expansion. The states we obtain can be\\u000a interpreted as being in thermal equilibrium at the time when the scale factor a has a specific value a =

Claudio Dappiaggi; Thomas-Paul Hack; Nicola Pinamonti

2011-01-01

146

Fast Random Walker with Priors Using Precomputation for Interactive Medical Image Segmentation  

Microsoft Academic Search

\\u000a Updating segmentation results in real-time based on repeated user input is a reliable way to guarantee accuracy, paramount\\u000a in medical imaging applications, while making efficient use of an expert’s time. The random walker algorithm with priors is\\u000a a robust method able to find a globally optimal probabilistic segmentation with an intuitive method for user input. However,\\u000a like many other segmentation

Shawn Andrews; Ghassan Hamarneh; Ahmed Saad

2010-01-01

147

The So-Called Dandy-Walker Syndrome: Analysis of 12 Operated Cases  

Microsoft Academic Search

Twelve patients between the years of 1964 and 1971 underwent surgical treatment for the so-called Dandy-Walker syndrome at the Johns Hopkins Hospital. Five patients belonged to an early group (1–8 weeks); four patients to an intermediary group (3–20 months); and a late group consisted of three patients (3 years, 14 years and 34 years). The value of the various diagnostic

George B. Udvarhelyi; Melvin H. Epstein

1975-01-01

148

Manipulating magnetic moment in a magnetic domain wall under transverse magnetic fields near Walker threshold  

Microsoft Academic Search

Current-induced domain wall (DW) motion under transverse magnetic fields was investigated through micromagnetic simulation using the Landau-Lifshitz-Gilbert equation containing adiabatic and nonadiabatic spin torque terms. It was found that the transverse field aligned antiparallel to the magnetic moment of the DW promotes a nucleation of an antivortex core, which causes a temporal Walker breakdown and then causes the magnetic moment

Youngman Jang; Seungha Yoon; Seungkyo Lee; Kisu Lee; B. K. Cho

2010-01-01

149

Uniqueness of self-similar asymptotically Friedmann-Robertson-Walker spacetime in Brans-Dicke theory  

NASA Astrophysics Data System (ADS)

We investigate spherically symmetric self-similar solutions in Brans-Dicke theory. Assuming a perfect fluid with the equation of state p=(?-1)?(1<=?<2), we show that there are no nontrivial solutions which approach asymptotically to the flat Friedmann-Robertson-Walker spacetime if the energy density is positive. This result suggests that primordial black holes in Brans-Dicke theory cannot grow at the same rate as the size of the cosmological particle horizon.

Maeda, Hideki; Koga, Jun-Ichirou; Maeda, Kei-Ichi

2002-10-01

150

Seizures and the Dandy-Walker Syndrome: A Case of Suspected Pseudoseizures  

Microsoft Academic Search

Background: A major pitfall in the diagnosis of conversion disorder is the difficulty in ruling out organic causes. Methods: A 19-year-old female was referred with seizures and the Dandy-Walker syndrome. We continued the medical workup and also treated the patient with psychotherapy. Results: The patient’s symptoms gradually abated, however, the headaches remained. No neurologic illness evolved during the follow-up. Conclusions:

Iulian Iancu; Moshe Kotler; Neil Lauffer; Pinhas Dannon; Elie Lepkifker

1996-01-01

151

Increased Apoptosis of Myoblasts in Drosophila Model for the Walker-Warburg Syndrome  

Microsoft Academic Search

Walker-Warburg syndrome, a progressive muscular dystrophy, is a severe disease with various kinds of symptoms such as muscle weakness and occasional seizures. The genes of protein O-mannosyltransferases 1 and 2 (POMT1 and POMT2), fukutin, and fukutin-related protein are responsible for this syndrome. In our previous study, we cloned Drosophila orthologs of human POMT1 and POMT2 and identified their activity. However,

Morio Ueyama; Yoshihiro Akimoto; Tomomi Ichimiya; Ryu Ueda; Hayato Kawakami; Toshiro Aigaki; Shoko Nishihara; Mel B. Feany

2010-01-01

152

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)

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.

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

2013-12-01

153

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

SciTech Connect

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

Zhengyu Liu; Boyin Huang [Univ. of Wisconsin, Madison, WI (United States)

1997-07-01

154

Compaction properties of crystalline pharmaceutical ingredients according to the Walker model and nanomechanical attributes.  

PubMed

This study investigates the extent to which single-crystal mechanical properties of selected active ingredients (famotidine, nifedipine, olanzapine, piroxicam) influence their bulk compressibility and compactibility. Nanomechanical attributes of oriented single crystals were determined with instrumented nanoindentation, and bulk deformational properties were assessed with the Walker and Heckel models as well as the elastic relaxation index. Good correlations were established between bulk and single-crystal plasticity parameters: the Walker coefficient and indentation hardness. The Walker model showed more practical value for evaluating bulk deformational properties of the APIs investigated because their properties differed more distinctly compared to the Heckel model. In addition, it was possible to predict the elastic properties of the materials investigated at the bulk level because a correlation between the elastic relaxation index and compliance was established. The value of using indentation hardness for crystalline APIs was also confirmed because their compactibility at the bulk level was able to be predicted. Mechanically interlocked structures were characteristic of most polymorphic forms investigated, resulting in single crystals having isotropic mechanical properties. It was revealed that in such cases good correlations between single and bulk mechanical properties can be expected. The results imply that innate crystal deformational properties define their compressibility and compactibility properties to a great extent. PMID:24979532

Egart, M; Ili?, I; Jankovi?, B; Lah, N; Sr?i?, S

2014-09-10

155

Reunion Probabilities of N One-Dimensional Random Walkers with Mixed Boundary Conditions  

NASA Astrophysics Data System (ADS)

In this work we extend the results of the reunion probability of N one-dimensional random walkers to include mixed boundary conditions between their trajectories. The level of the mixture is controlled by a parameter c , which can be varied from c=0 (independent walkers) to c? infty (vicious walkers). The expressions are derived by using Quantum Mechanics formalism (QMf) which allows us to map this problem into a Lieb-Liniger gas (LLg) of N one-dimensional particles. We use Bethe ansatz and Gaudin's conjecture to obtain the normalized wave-functions and use this information to construct the propagator. As it is well-known, depending on the boundary conditions imposed at the endpoints of a line segment, the statistics of the maximum heights of the reunited trajectories have some connections with different ensembles in Random Matrix Theory. Here we seek to extend those results and consider four models: absorbing, periodic, reflecting, and mixed. In all four cases, the probability that the maximum height is less or equal than L takes the form F_N(L)=A_Nsum _{\\varvec{k}in ? _{{B}}} e^{-sum _{j=1}^Nk_j^2}{V}_N(\\varvec{k}) , where A_N is a normalization constant, {V}_N(\\varvec{k}) contains a deformed and weighted Vandermonde determinant, and ? _{{B}} is the solution set of quasi-momenta \\varvec{k} obeying the Bethe equations for that particular boundary condition.

Castillo, Isaac Pérez; Dupic, Thomas

2014-05-01

156

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

NASA Technical Reports Server (NTRS)

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.

1962-01-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

158

Contemporary Fault Slip Rates in the Southern Walker Lane from Block Modeling of GPS Data  

NASA Astrophysics Data System (ADS)

The southern Walker Lane is a right-lateral shear zone 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 1/2 the observed regional current geodetic rate of right-lateral shear. In order to better understand the modern distribution of strain accumulation and release across this region, we established a dense network of 50 new and existing campaign GPS monuments (from MAGNET and other networks). GPS data were processed using GIPSY-OASIS software to obtain sub-cm precision locations. To determine a new regional crustal velocity field we combine data from surveys of entirely new monuments only instrumented in 2010 and 2011 with existing monuments that were first instrumented as early as 1994, and reoccupied in 2010/11. We will report on initial velocity results for campaigns through 2011. As well, we will report on our successes with using the determined velocities in a modern regional block model (Meade and Loveless, BSSA 2009) to determine slip rates on individual faults in the southern Walker Lane. Elucidating slip on individual structures allows for a better accounting of slip across the region, and helps reveal distributed deformation that may not be preserved in the geologic record. These new results have important implications for the temporal and spatial distribution of strain accumulation and release along this portion of an evolving plate boundary.

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

2011-12-01

159

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

NASA Astrophysics Data System (ADS)

Accommodating ~20-25% of the dextral-motion between the Pacific and North American plates the Walker Lane is represented as an elongate, NW oriented, region of active tectonics positioned between the northwesterly-translating Sierra Nevada microplate and the east-west extension of the Basin and Range. This region of transtension is being variably accommodated on regional-scale systems of predominantly strike-slip faulting. At the western edge of the central Walker Lane (ca. 38°-39°N latitude) is a region of crustal-scale blocks bounded by wedge-shaped depositional-basins and normal-fault systems, here defined as the west-central Walker Lane (WCWL). Devoid of obvious strike-slip faulting, the presence of tectonic-block vertical-axis rotations in the WCWL represents unrecognized components of dextral-shearing and/or changes of strain-accommodation over time. We use paleomagnetic reference directions for Eureka Valley Tuff (EVT) members of the late Miocene Stanislaus Group as spatial and temporal markers for documentation of tectonic-block vertical-axis rotations near Bridgeport, CA. Study-site rotations revealed discrete rotational domains of mean vertical-axis rotation ranging from ~10°-30° with heterogeneous regional distribution. Additionally, the highest measured magnitudes of vertical-axis rotation (~50°-60° CW) define a 'Region of High Strain' that includes the wedge-shaped Bridgeport Valley (Basin). This study revealed previously-unrecognized tectonic rotation of reference direction sites from prior studies for two (By-Day and Upper) of the three members of the EVT, resulting in under-estimates of regional strain accommodation by these studies. Mean remanent directions and virtual geomagnetic poles utilized in our study yielded a recalculated reference direction for the By-Day member of: Dec.=353.2°; Inc.= 43.7°; ?95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously unrecognized reference site rotations, and provided an additional reference direction for determining vertical-axis rotation magnitudes. We present a kinematic model based on mean rotation magnitudes of ~30° CW for the Sweetwater Mountains and Bodie Hills that accounts for rotational-strain accommodation of dextral shear in the WCWL since the late Miocene. This model considers rotational magnitudes, paleostrain indicators, edge-effects, and strain-accommodating structures of rotating crustal blocks to represent changes in regional strain accommodation over time. The results and models presented here elucidate the complicated and evolving nature of the WCWL, and further understanding of variations in strain accommodation for the Walker Lane.

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

2012-12-01

160

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

PubMed Central

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

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

2014-01-01

161

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

NASA Astrophysics Data System (ADS)

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.

Nadjafikhah, Mehdi; Jafari, Mehdi

2013-12-01

162

Relationship between 2+1 and 3+1 Friedmann-Robertson-Walker cosmologies  

NASA Astrophysics Data System (ADS)

In this work we establish the correspondence between solutions to the Friedmann-Robertson-Walker cosmologies for perfect fluid and scalar field sources, where both satisfy state equations of the form p+?=?f(?), not necessarily linear ones. Such state equations are of common use in the case of matter fluids; nevertheless, for a scalar field, they introduce relationships on the potential and kinetic scalar field energies which restrict the set of solutions. A theorem in this respect is demonstrated: From any given 3+1 cosmological solution, obeying the quoted state equations, one can derive its 2+1 cosmological counterpart or vice versa. Some applications are given.

García, Alberto A.; Cataldo, Mauricio; del Campo, Sergio

2003-12-01

163

Detection of the relevant type of locomotion in infancy: crawlers versus walkers.  

PubMed

Human infants show a preference for individuals who are similar to them. Using point-light displays of human walkers and crawlers as stimuli, we examined whether infants' preference for the motions of crawling and walking changes between, before, and after the onset of bipedal walking. The results show that crawling and walking infants prefer the types of locomotion that are similar to their own, respectively. These indicate that the infants detect the similarities between the motions they performed and they observed, which provides the behavioral evidence that the production of a particular motion is connected to its perception in infancy. PMID:18771803

Sanefuji, Wakako; Ohgami, Hidehiro; Hashiya, Kazuhide

2008-12-01

164

Transitional forms of Arnold-Chiari and Dandy-Walker malformations.  

PubMed

The morphological findings in 12 cases of Arnold-Chiari and 3 cases of Dandy-Walker malformations are described and compared to those in 2 cases of congenital hydrocephalus of unknown origin, 1 case of isolated meningo-myelocele and 2 cases of normal newborn brains. Lesions common to both types of malformation indicate a same time-related embryogenetic defect of the roofplate of the rhombencephalon, that does not allow the inferior vermis and the choroid plexus to turn inward into the fourth ventricle. PMID:51918

De Reuck, J; vander Eecken, H

1975-09-01

165

The field descriptions for thermal-equilibrium Friedmann-Robertson-Walker universe  

NASA Astrophysics Data System (ADS)

In this paper, we show the simple expression for the energy density of the thermal-equilibrium Friedmann-Robertson-Walker (TEFRW) universe and study the problem how to describe it by using some field models. We analyze the properties of the quintessence field in the quintessence model, calculate the tachyon potential in the tachyon model and point out that the latter model cannot give the whole description for the TEFRW universe. It is found that the two-field model can be responsible for describing the whole evolution process of the TEFRW universe.

Lan, Tianbao; Wei, Yihuan; Fu, Yanyan; Zhang, Yuezhu

2014-06-01

166

Encounter distribution of two random walkers on a finite one-dimensional interval  

NASA Astrophysics Data System (ADS)

We analyse the first-passage properties of two random walkers confined to a finite one-dimensional domain. For the case of absorbing boundaries at the endpoints of the interval, we derive the probability that the two particles meet before either one of them becomes absorbed at one of the boundaries. For the case of reflecting boundaries, we obtain the mean first encounter time of the two particles. Our approach leads to closed-form expressions that are more easily tractable than a previously derived solution in terms of the Weierstrass’ elliptic function.

Tejedor, Vincent; Schad, Michaela; Bénichou, Olivier; Voituriez, Raphael; Metzler, Ralf

2011-09-01

167

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

USGS Publications Warehouse

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.

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

1983-01-01

168

Conformally invariant formalism for the electromagnetic field with currents in Robertson-Walker spaces  

NASA Astrophysics Data System (ADS)

We show that the Laplace-Beltrami equation \\squarelg 6a = j in (R6,?), ? \\colone diag(+ - - - - +), leads under very moderate assumptions to both the Maxwell equations and the conformal Eastwood-Singer gauge condition on conformally flat spaces including the spaces with a Robertson-Walker metric. This result is obtained through a geometric formalism which gives, as byproduct, simplified calculations. In particular, we build an atlas for all the conformally flat spaces considered which allows us to fully exploit the Weyl rescalling to Minkowski space.

Huguet, E.; Renaud, J.

2013-02-01

169

Pendulum walker  

NASA Astrophysics Data System (ADS)

Picture someone walking from left to right. During one step (intra-step) we treat them as a simple pendulum. This model is called the rimless wheel in the literature. We analyze this model intra-step using dynamic programming to find the optimum energy profile based on time and energy cost. We then analyze the problem inter-step for the ideal stepsize based on time cost alone, i.e., without foot collision (energy) losses.

Muench, Paul; Marecki, Alexander

2007-05-01

170

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

171

Baseline-Dependent Effect of Noise-Enhanced Insoles on Gait Variability in Healthy Elderly Walkers  

PubMed Central

The purpose of this study was to determine whether providing subsensory stochastic-resonance mechanical vibration to the foot soles of elderly walkers could decrease gait variability. In a randomized double-blind controlled trial, twenty nine (29) subjects engaged in treadmill walking while wearing sandals customized with three (3) actuators capable of producing stochastic-resonance mechanical vibration embedded in each sole. For each subject, we determined a subsensory level of vibration stimulation. After a 5-minute acclimation period of walking with the footwear, subjects were asked to walk on the treadmill for six (6) trials, each thirty (30) seconds long. Trials were pair-wise random: in three trials, actuators provided subsensory vibration; in the other trials, they did not. Subjects wore reflective markers to track body motion. Stochastic-resonance mechanical stimulation exhibited baseline-dependent effects on spatial stride-to-stride variability in gait, slightly increasing variability in subjects with least baseline variability and providing greater reductions in variability for subjects with greater baseline variability (p < .001). Thus, applying stochastic-resonance mechanical vibrations on the plantar surface of the foot reduces gait variability for subjects with more variable gait. Stochastic-resonance mechanical vibrations may provide an effective intervention for preventing falls in healthy elderly walkers.

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

2014-01-01

172

Changes in liver gluconeogenesis during the development of Walker-256 tumour in rats  

PubMed Central

Few studies have investigated liver gluconeogenesis in cancer and there is no agreement as to whether the activity of this pathway is increased or decreased in this disease. The aim of this study was to evaluate gluconeogenesis from alanine, pyruvate and glycerol, and related metabolic parameters in perfused liver from Walker-256 tumour-bearing rats on days 5 (WK5 group), 8 (WK8 group) and 12 (WK12 group) of tumour development. There was reduction (P < 0.05) of liver glucose production from alanine and pyruvate in WK5, WK8 and WK12 groups, which was accompanied by a decrease (P < 0.05) in oxygen consumption. Moreover, there was higher (P < 0.05) pyruvate and lactate production from alanine in the WK5 group and a marked reduction (P < 0.05) of pyruvate and urea production from alanine in the WK12 group. In addition, liver glucose production and oxygen consumption from glycerol were not reduced in WK5, WK8 and WK12 groups. Thus the, the results show inhibition of hepatic gluconeogenesis from alanine and pyruvate, but not from glycerol, on days 5, 8 and 12 of Walker-256 tumour development, which can be attributed to the metabolic step in which the substrate enters the gluconeogenic pathway.

Moreira, Carolina Campos Lima; Cassolla, Priscila; Dornellas, Ana Paula Segantini; Morais, Hely; Souza, Camila Oliveira; Borba-Murad, Glaucia Regina; Bazotte, Roberto Barbosa; Souza, Helenir Medri

2013-01-01

173

Analysis of growth directions of columnar stromatolites from Walker Lake, western Nevada.  

PubMed

Samples of digitate, branching, columnar stromatolites were collected from the steep sides and near horizontal top of four in situ boulders located on the southwestern side of Walker Lake, Nevada, to test the widely held assumption that stromatolite column formation represents a phototropic response. We would predict that the columns on the steeply dipping sides of the boulder would bend upwards toward the light during growth if phototropism was significant during stromatolite morphogenesis. Angle of growth measurements on >300 stromatolites demonstrate that the stromatolites grew nearly normal to their growth surface, regardless of the inclination of their growth surface. No significant differences in the distribution of growth angles between north-, south-, east-, or west-facing samples were observed, and stromatolite lamina thickness did not systematically vary with position on the boulder. The lack of a strong phototropic response does not rule out a biological origin for the Walker Lake structures, but it does suggest that phototropic growth was not a dominant factor controlling stromatolite morphogenesis in these stromatolites and that column formation cannot be uniquely attributed as a phototropic response in stromatolites. It is interesting to note that the morphology of the stromatolites on the top of the boulder is identical to stromatolites on the steep sides. Stromatolite morphogenetic models that predict branching typically require a vertically directed sedimentary component, a feature that would have likely affected the stromatolites on the tops of the boulders, but not the sides, suggesting that other factors may be important in stromatolite morphogenesis. PMID:21884363

Petryshyn, V A; Corsetti, F A

2011-09-01

174

An anxiety-induced bias in the perception of a bistable point-light walker.  

PubMed

Human sensitivity for social cues is exquisite, as illustrated by the ease with which simplified point-light movements invoke social and emotional responses. Compared to faces, these biological motion stimuli only recently started to be used to explore questions regarding social cognition and anxiety. We presented human point-light walkers that could be perceived as facing towards or facing away from the observer, and tested whether participants with high social anxiety would perceive these bistable stimuli differently, because this type of stimuli has particular relevance for them. The results showed that observers with high social anxiety tended to see walkers as facing away more frequently than those with low social anxiety. This may mean that high socially anxious observers are biased towards the more positive perceptual alternative because they are motivated to protect themselves against threatening social experiences, but we also explore alternative explanations. The findings are in line with the evidence for a positivity bias in perception, also called wishful seeing, but in contrast with the attentional negativity bias often found in social anxiety. We discuss reasons for this divergence and possible limitations of the current study. PMID:24140822

Van de Cruys, Sander; Schouten, Ben; Wagemans, Johan

2013-11-01

175

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

PubMed Central

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 PKC? 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 PKC?, 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, NF?B 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.

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

2014-01-01

176

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

SciTech Connect

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.

Yount, J.C. [Geological Survey, Reno, NV (USA); Quimby, M.F. [Geological Survey, Menlo Park, CA (USA)

1990-11-01

177

NetWalker: a contextual network analysis tool for functional genomics  

PubMed Central

Background Functional analyses of genomic data within the context of a priori biomolecular networks can give valuable mechanistic insights. However, such analyses are not a trivial task, owing to the complexity of biological networks and lack of computational methods for their effective integration with experimental data. Results We developed a software application suite, NetWalker, as a one-stop platform featuring a number of novel holistic (i.e. assesses the whole data distribution without requiring data cutoffs) data integration and analysis methods for network-based comparative interpretations of genome-scale data. The central analysis components, NetWalk and FunWalk, are novel random walk-based network analysis methods that provide unique analysis capabilities to assess the entire data distributions together with network connectivity to prioritize molecular and functional networks, respectively, most highlighted in the supplied data. Extensive inter-operability between the analysis components and with external applications, including R, adds to the flexibility of data analyses. Here, we present a detailed computational analysis of our microarray gene expression data from MCF7 cells treated with lethal and sublethal doses of doxorubicin. Conclusion NetWalker, a detailed step-by-step tutorial containing the analyses presented in this paper and a manual are available at the web site http://netwalkersuite.org.

2012-01-01

178

Analog Landau-He-McKellar-Wilkens quantization due to noninertial effects of the Fermi-Walker reference frame  

NASA Astrophysics Data System (ADS)

We will show that when a neutral particle with permanent electric dipole moment interacts with a specific field configuration when the local reference frames of the observers are Fermi-Walker transported, the Landau quantization analog to the He-McKellar-Wilkens setup arises in the nonrelativistic quantum dynamics of the neutral particle due the noninertial effects of the Fermi-Walker reference frame. We show that the noninertial effects do not break the infinity degeneracy of the energy levels, but in this case, the cyclotron frequency depends on the angular velocity.

Bakke, Knut

2010-05-01

179

Commentary on Walker, Brantley, and Rigsbee's (2004) “A Critical Analysis of Parental Alienation Syndrome and Its Admissibility in the Family Court”  

Microsoft Academic Search

In this response to Walker et al. (2004), we explain our perspective, recent research, and recommendations in order to correct some misunderstandings of our work on alienated children. Then we address some important issues that Walker et al. have raised that deserve the attention of the field. These include whether a child necessarily needs a relationship with both parents; when

Janet R. Johnston; Joan B. Kelly

2004-01-01

180

?-Linolenic acid and eicosapentaenoic acid induce modifications in mitochondrial metabolism, reactive oxygen species generation, lipid peroxidation and apoptosis in Walker 256 rat carcinosarcoma cells  

Microsoft Academic Search

The polyunsaturated fatty acids ?-linolenic acid (GLA) and eicosapentaenoic acid (EPA) are cytotoxic to tumour cells. GLA inhibits Walker 256 tumour growth in vivo, causing alterations in mitochondrial ultrastructure and cellular metabolism. The objective of the present study was to investigate the mechanisms behind fatty acid inhibition of Walker 256 tumour growth under controlled in vitro conditions. At a concentration

Alison Colquhoun; Robert I Schumacher

2001-01-01

181

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

NASA Astrophysics Data System (ADS)

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.

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

182

A rat model of bone cancer pain induced by intra-tibia inoculation of Walker 256 mammary gland carcinoma cells  

Microsoft Academic Search

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

Qi-Liang Mao-Ying; Jun Zhao; Zhi-Qiang Dong; Jun Wang; Jin Yu; Min-Fen Yan; Yu-Qiu Zhang; Gen-Cheng Wu; Yan-Qing Wang

2006-01-01

183

[Physical risks whilst walking the Nijmegen Four Days Marches in 2007: electrolyte imbalance in 1 in 5 walkers  

Microsoft Academic Search

OBJECTIVE: To determine the physiological impact and health risks for walkers during the Nijmegen (the Netherlands) Four Days Marches in 2007, the largest walking event in the world with more than 45,000 participants. DESIGN: Observational study. METHODS: 66 volunteers were randomly selected and counterbalanced for distance walked and gender in this observational study. Subjects walked 30 km (n = 20;

T. M. H. Eijsvogels; D. H. J. Thijssen; F. Poelkens; M. Binkhorst; C. W. Wouters; B. J. J. W. Schouwenberg; M. T. E. Hopman

2008-01-01

184

Taxonomic study of the genus Assara Walker (Lepidoptera, Pyralidae, Phycitinae) in NE China, with description of a new species.  

PubMed

Four species of the genus Assara Walker, 1863 are revised from NE China. Among them, Assara yanbianensis Bae & Qi sp. n. is described as new to science and A. terebrella (Zincken, 1818) is newly recorded from China. A key to the NE Chinese species of the genus Assara with illustrations of adults and genitalia are presented. PMID:24943428

Qi, Mu-Jie; Han, Hui-Lin; Park, Bo-Sun; Bae, Yang-Seop

2014-01-01

185

Acclimation in Simulated Lake Water Increases Survival of Lahontan Cutthroat Trout Challenged with Saline, Alkaline Water from Walker Lake, Nevada  

Microsoft Academic Search

We investigated the effect of acclimation and condition factor (K) on short-term survival of subyearling Lahontan cutthroat trout Oncorhynchus clarkii henshawi reared at Lahontan National Fish Hatchery, Gardnerville, Nevada, and challenged for 1 week with saline, alkaline water from Walker Lake, Nevada. The effect of acclimation and lake-water challenge on plasma osmolality was also investigated. Fish were acclimated for 0,

John P. Bigelow; Wendy M. Rauw; Luis Gomez-Raya

2010-01-01

186

Australasian evidence for mid-holocene climate change implies precessional control of Walker Circulation in the Pacific  

Microsoft Academic Search

At its simplest, the Pacific cell of the Walker Circulation may be regarded as a thermal circulation, driven by the temperature contrast between the west and east Pacific. Evidence from Australasia is summarized, indicating that this circulation was greatly weakened in the early Holocene but was enhanced at about 5000 BP. The initial effect of this enhancement was the intensification

James Shulmeister

1999-01-01

187

Rice white stemborer Scirpophaga innotata (Walker) in southern Mindanao, Philippines. II. Synchrony of planting and natural enemies  

Microsoft Academic Search

Although the rice white stemborer (WSB) Scirpophaga innotata (Walker) has been an epidemic pest in other locations in the Philippines and Indonesia, its population has remained at chronic pest levels in Koronadal, southern Mindanao, Philippines. Field studies were undertaken to determine the role of egg parasitoids and general predators in suppressing WSB numbers. The results revealed greater mortality levels on

J. A. Litsinger; A. L. Alviola; C. G. Dela Cruz; B. L. Canapi; E. H. Batay-An III; A. T. Barrion

2006-01-01

188

Endoscopic Transtentorial Ventriculocystostomy and Cystoventriculoperitoneal Shunt in a Neonate with Dandy-Walker Malformation and Associated Aqueductal Obstruction  

Microsoft Academic Search

Objective: Shunting of the lateral ventricle and the posterior fossa cyst is the advocated surgical therapy for children with Dandy-Walker malformation (DWM) and associated aqueductal obstruction. The high rate of complications of combined shunting stimulated the authors to search for an alternative surgical solution. Clinical Presentation\\/Intervention: After transtentorial endoscopic ventriculocystostomy, a cystoventricular catheter, connected to a peritoneal shunt, was placed

Martin R. Weinzierl; Volker A. Coenen; Marcus C. Korinth; Joachim M. Gilsbach; Veit Rohde

2005-01-01

189

A 1200 year record of hydrologic variability in the Sierra Nevada from sediments in Walker Lake, Nevada  

Microsoft Academic Search

Measurements of the oxygen isotopic composition (?18O) of the total inorganic carbon (TIC) fraction from cored sediments of Walker Lake, Nevada, were conducted at an average resolution of ?3 years per sample over the last 1200 years. On the basis of radiocarbon analysis on the total organic carbon (TOC) fraction, a ?18O time series was created to reconstruct changes in

Fasong Yuan; Braddock K. Linsley; Steve P. Lund; John P. McGeehin

2004-01-01

190

Detection of an Alu insertion in the POMT1 gene from three French Walker Warburg syndrome families  

Microsoft Academic Search

Walker Warburg syndrome (WWS) is the most severe of a group of multiple congenital disorders known as lissencephaly type II ( LIS Type II) associated with congenital muscular dystrophy and eye abnormalities. The POMT1 gene is the most frequently affected found in 20% of patients with WWS. We describe five fetuses with WWS in three non-related families carrying a same

C. Bouchet; S. Vuillaumier-Barrot; M. Gonzales; S. Boukari; C. Le Bizec; C. Fallet; A.-L. Delezoide; H. Moirot; A. Laquerriere; F. Encha-Razavi; G. Durand; N. Seta

2007-01-01

191

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

PubMed Central

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

Wu, Chun-Sheng; Solovyev, Alexey V.

2011-01-01

192

Oral-facial-digital syndrome type 1 with hypothalamic hamartoma and Dandy-Walker malformation.  

PubMed

We report a 1-year-old girl with oral-facial-digital syndrome type 1 with multiple malformations of the oral cavity, face, digits, and central nervous system, including agenesis of the corpus callosum, the presence of intracerebral cysts, and agenesis of the cerebellar vermis, which is associated with the subarachnoid space separating the medial sides of the cerebellar hemispheres. This child also had a hypothalamic hamartoma and a Dandy-Walker malformation, which have not been reported previously. The clinical features, including cerebral malformations, in several types of oral-facial-digital syndrome, overlap with each other. Further accumulation of new case reports and identification of new genetic mutations in oral-facial-digital syndrome may provide novel and important insights into the genetic mechanisms of this syndrome. PMID:23498571

Azukizawa, Takayuki; Yamamoto, Masahito; Narumiya, Seirou; Takano, Tomoyuki

2013-04-01

193

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

PubMed

Traditional methods of volatile detection used by police typically consist of reliance on canine olfaction. However, dogs have some limitations such as cost of training and time of conditioning. The possibility of using parasitic wasps for detecting explosives and narcotics has been developed. Moreover, wasps are cheap to produce and can be conditioned with impressive speed for a specific chemical detection task. We examined the ability of Nasonia vitripennis Walker to learn and respond to methyldisulfanylmethane (DMDS), a volatile discriminator of cadaver. The training aimed to form an association between an unconditioned stimulus (pupae) and the conditioned stimulus (odor source). After the training, the time spent by conditioned wasps in the DMDS chamber was measured. Statistical analysis showed that the increasing concentrations involved an increase in the time spent in the chamber containing DMDS. This study indicates that N. vitripennis can respond to DMDS, which provide further support for its development as a biological sensor. PMID:24313637

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

2014-03-01

194

Beating the walker limit with massless domain walls in cylindrical nanowires.  

PubMed

We present a micromagnetic study on the current-induced domain-wall motion in cylindrical Permalloy nanowires with diameters below 50 nm. The transverse domain walls forming in such thin, round wires are found to differ significantly from those known from flat nanostrips. In particular, we show that these domain walls are zero-mass micromagnetic objects. As a consequence, they display outstanding dynamic properties, most importantly the absence of a breakdown velocity generally known as the Walker limit. Our simulation data are confirmed by an analytic model which provides a detailed physical understanding. We further predict that a particular effect of the current-induced dynamics of these domain walls could be exploited to measure the nonadiabatic spin-transfer torque coefficient. PMID:20366793

Yan, Ming; Kákay, Attila; Gliga, Sebastian; Hertel, Riccardo

2010-02-01

195

A truncating mutation in B3GNT1 causes severe Walker-Warburg syndrome.  

PubMed

Walker-Warburg syndrome (WWS) is a genetically heterogeneous form of congenital muscular dystrophy with significant brain and ocular involvement. In a multiplex consanguineous family with severe WWS phenotype, autozygome-guided sequencing of previously reported WWS genes was negative. Exome sequencing followed by autozygome filtration revealed a homozygous two-base pair insertion in B3GNT1 (NM_006876.2:c.821_822insTT), leading to premature truncation of the protein (p.Glu274Aspfs*94). Recently, two missense mutations in this gene have been reported as probably causal in a family with WWS. This report describes the first truncating mutation in B3GNT1 and confirms that this gene, which plays a role in ?DG glycosylation, is a bona fide disease gene in WWS. PMID:23877401

Shaheen, Ranad; Faqeih, Eissa; Ansari, Shinu; Alkuraya, Fowzan S

2013-11-01

196

Decay of massive particles in Robertson-Walker universes with statically bounded expansion laws  

NASA Astrophysics Data System (ADS)

Mutually interacting quantum fields in 3-flat Robertson-Walker universes are examined. The decay of a massive scalar Phi particle into two massless scalar Psi particles is calculated exactly on the basis of the interaction picture and an in-out approach based on an S matrix. The cosmic scale factor alpha(eta) is thereby specified as (1) a step expansion law and (2) a tanh-expansion law which represents the prototype of a smoothed-out step law. The characteristic modifications of the Minkowskian decay spectrum are examined. A comparison of amplitudes and decay probabilities for the step and tanh expansion laws demonstrates that smoothing out the step introduces a gravitational influence of nonvanishing duration, which leads essentially to finite corrections of the step results.

Audretsch, Juergen; Rueger, Alexander; Spangehl, Peter

1987-07-01

197

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

PubMed Central

The relative importance of north–south migrations of the intertropical convergence zone (ITCZ) versus El Niño-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that north–south ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability profoundly influenced tropical Pacific hydrology. We present hydrological reconstructions from Cattle Pond, Dongdao Island of the South China Sea, where multi-decadal rainfall and downcore grain size variations are correlated to the Southern Oscillation Index during the instrumental era. Our downcore grain size reconstructions indicate that this site received less precipitation during relatively warm periods, AD 1000–1400 and AD 1850–2000, compared with the cool period (AD 1400–1850). Including our new reconstructions in a synthesis of tropical Pacific records results in a spatial pattern of hydrologic variability that implicates the PWC.

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

2011-01-01

198

Complex-mass particles in the Robertson-Walker-de sitter space  

SciTech Connect

The relativistic scalar wave equation specialized for the Robertson-Walker space, and its solutions for the case of de Sitter expansion, have been considered and interpreted. It is shown that in de Sitter universe particles occurred in a resonance form Z{sub 0} = M{sub 0} + i{mu}{sub 0} = 3H{Dirac_h}/2c{sup 2} strictly connected to the Hubble parameter. A perfect fluid of imaginary-mass particles as a model of cosmological ether at this stage is proposed. Propagation of matter waves in such a medium may be conceived as an inelastic scattering process mediated by the slower-than-light particles with imaginary rest mass i{mu}{sub 0}. 31 refs.

Molski, M. [A. Mickiewicz Univ., Poznan (Poland)

1993-02-01

199

Comparison of rat liver and Walker 256 carcinosarcoma tRNAs.  

PubMed Central

The complete nucleotide sequences of both rat liver and Walker 256 mammary carcinosarcoma tRNAAsn reveal that they are identical except for the nucleotide present in the wobble position of the anticodon loop. The rat liver tRNAAsn contains the Q nucleoside, whereas the tumour tRNAAsn contains an unmodified guanosine. The tRNAs from both tissues also show significant quantitative differences in the chromatographic mobilities for isoaccepting species of tRNAAsp, tRNAAsn, tRNAHis and tRNATyr. In addition, chromatographic shifts upon cyanogen bromide treatment and analyses of the alkaline hydrolysates of these tRNAs demonstrate that those of tumour origin contain significantly less Q and Q nucleoside than their normal rat liver counterparts. Images

Roe, B A; Stankiewicz, A F; Rizi, H L; Weisz, C; DiLauro, M N; Pike, D; Chen, C Y; Chen, E Y

1979-01-01

200

Movement strategies and sensory reweighting in tandem stance: differences between trained tightrope walkers and untrained subjects.  

PubMed

Does skill with a difficult task, such as tightrope walking, lead to improved balance through altered movement strategies or through altered weighting of sensory inputs? We approached this question by comparing tandem stance (TS) data between seven tightrope walkers and 12 untrained control subjects collected under different sensory conditions. All subjects performed four TS tasks with eyes open or closed, on a normal firm or foam surface (EON, ECN, EOF, ECF); tightrope walkers were also tested on a tightrope (EOR). Head, upper trunk and pelvis angular velocities were measured with gyroscopes in pitch and roll. Power spectral densities (PSDs) ratios, and transfer function gains (TFG) between these body segments were calculated. Center of mass (CoM) excursions and its virtual time to contact a virtual base of support boundary (VTVBS) were also estimated. Gain nonlinearities, in the form of decreased trunk to head and trunk to pelvis PSD ratios and TFGs, were present with increasing sensory task difficulty for both groups. PSD ratios and TFGs were less in trained subjects, though, in absolute terms, trained subjects moved their head, trunk, pelvis and CoM faster than controls, and had decreased VTVBS. Head roll amplitudes were unchanged with task or training, except above 3Hz. CoM amplitude deviations were not less for trained subjects. For the trained subjects, EOR measures were similar to those of ECF. Training standing on a tightrope induces a velocity modification of the same TS movement strategy used by untrained controls. More time is spent exploring the limits of the base of support with an increased use of fast trunk movements to control balance. Our evidence indicates an increased reliance on neck and pelvis proprioceptive inputs. The similarity of TS on foam to that on the tightrope suggests that the foam tasks are useful for effective training of tightrope walking. PMID:24090964

Honegger, F; Tielkens, R J M; Allum, J H J

2013-12-19

201

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

SciTech Connect

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

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

1989-01-01

202

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

203

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

NASA Astrophysics Data System (ADS)

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 (~38.0°N) to the latitude of Lake Tahoe (~39.5°N) 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.

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

2010-12-01

204

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

USGS Publications Warehouse

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.

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

1989-01-01

205

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

NASA Technical Reports Server (NTRS)

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.

1953-01-01

206

Applicability of the Ben-Tovim Walker Body Attitudes Questionnaire (BAQ) and the Attention to Body Shape scale (ABS) in Japanese males and females  

Microsoft Academic Search

ObjectivesTo determine applicability of the Japanese-translated versions of the Ben-Tovim Walker Body Attitudes Questionnaire (BAQ) and the Attention to the Body Shape Scale (ABS) in Japanese males and females.

Masaharu Kagawa; Hayato Uchida; Kazuhiro Uenishi; Colin W. Binns; Andrew P. Hills

2007-01-01

207

Disparate requirements for the Walker A and B ATPase motifs of human RAD51D in homologous recombination  

Microsoft Academic Search

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 require- ment for these motifs in interactions with XRCC2 and RAD51C, and for survival of cells in response to DNA interstrand crosslinks (ICLs). Ectopic expression of

Claudia Wiese; John M. Hinz; Robert S. Tebbs; Peter B. Nham; Salustra S. Urbin; David W. Collins; Larry H. Thompson; David Schild

2006-01-01

208

Review of the genus Tinissa Walker, 1864 (Lepidoptera, Tineidae, Scardiinae) from China, with description of five new species  

PubMed Central

Abstract The genus Tinissa Walker is reviewed for China. Seven species are recognized, of which Tinissa apicimaculata sp. n., Tinissa conchata sp. n., Tinissa connata sp. n.,Tinissa leguminella sp. n. and Tinissa spirella sp. n. are described as new; and Tinissa insularia Robinson, 1976 is newly recorded from China. Photographs of the adults and illustrations of the genitalia are given. A key to all the known Chinese species and a distribution map of Tinissa in China are included.

Yang, Linlin; Li, Houhun

2012-01-01

209

Evolution of the Indo-Pacific Warm Pool and Hadley-Walker Circulation since the Last Deglaciation  

Microsoft Academic Search

The Indo-Pacific warm pool (IPWP), East Pacific cold tongue, and deep overturning atmospheric Hadley (meridional) and Walker\\u000a (zonal) circulations form a tightly coupled system. In this chapter, we explore the concept of the Hadley circulation as the\\u000a fundamental driver of changes in this system, and examine its possible impact on global climates of the past. Recent modeling\\u000a studies indicate that

Michael K. Gagan; Lonnie G. Thompson

210

VarWalker: Personalized Mutation Network Analysis of Putative Cancer Genes from Next-Generation Sequencing Data  

PubMed Central

A major challenge in interpreting the large volume of mutation data identified by next-generation sequencing (NGS) is to distinguish driver mutations from neutral passenger mutations to facilitate the identification of targetable genes and new drugs. Current approaches are primarily based on mutation frequencies of single-genes, which lack the power to detect infrequently mutated driver genes and ignore functional interconnection and regulation among cancer genes. We propose a novel mutation network method, VarWalker, to prioritize driver genes in large scale cancer mutation data. VarWalker fits generalized additive models for each sample based on sample-specific mutation profiles and builds on the joint frequency of both mutation genes and their close interactors. These interactors are selected and optimized using the Random Walk with Restart algorithm in a protein-protein interaction network. We applied the method in >300 tumor genomes in two large-scale NGS benchmark datasets: 183 lung adenocarcinoma samples and 121 melanoma samples. In each cancer, we derived a consensus mutation subnetwork containing significantly enriched consensus cancer genes and cancer-related functional pathways. These cancer-specific mutation networks were then validated using independent datasets for each cancer. Importantly, VarWalker prioritizes well-known, infrequently mutated genes, which are shown to interact with highly recurrently mutated genes yet have been ignored by conventional single-gene-based approaches. Utilizing VarWalker, we demonstrated that network-assisted approaches can be effectively adapted to facilitate the detection of cancer driver genes in NGS data.

Jia, Peilin; Zhao, Zhongming

2014-01-01

211

Immunofluorescence study of a muscle biopsy from a 1-year-old patient with Walker-Warburg syndrome  

Microsoft Academic Search

A previous study of two patients with Walker-Warburg syndrome (WWS) showed a severe deficiency of the extracellular matrix\\u000a protein laminin ?2 chain and ?-sarcoglycan (adhalin) in skeletal muscle fibers. More recently, however, other researchers\\u000a have shown that in their WWS patients the expression of the laminin ?2 chain and ?-sarcoglycan was normal. Here we describe\\u000a a 1-year-old boy affected with

Marcello Villanova; Patrizia Sabatelli; Yi He; Alessandro Malandrini; Stefania Petrini; Nadir M. Maraldi; Luciano Merlini

1998-01-01

212

Interstitial deletion of 8q21â22 associated with minor anomalies, congenital heart defect, and Dandy-Walker variant  

Microsoft Academic Search

We describe an infant with a deletion of 8q21â22 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

Margaret L. Donahue; Rita M. Ryan

1995-01-01

213

Lithostratigraphy, magnetostratigraphy, and radiometric dating of the Stanislaus Group, CA, and age of the Little Walker Caldera  

Microsoft Academic Search

The Miocene Stanislaus Group (Stanislaus, Calaveras, Tuolomne, Alpine and Mono counties, CA), composed of intercalated latite and quartz-latite (trachyandesite and trachyte\\/trachydacite) lavas and ignimbrites, provides an important marker for reconstructing the elevation history and tectonic development of the Sierra Nevada and Walker Lane. We present new Ar\\/Ar geochronology and magnetostratigraphy indicating that the Stanislaus Group was emplaced in two pulses:

Christopher J. Pluhar; Alan L. Deino; Nathan M. King; Cathy Busby; Brian P. Hausback; Tracy Wright; Collin Fischer

2009-01-01

214

ECOLOGY AND DEMOGRAPHICS OF HANTAVIRUS INFECTIONS IN RODENT POPULATIONS IN THE WALKER RIVER BASIN OF NEVADA AND CALIFORNIA  

Microsoft Academic Search

To study the ecologic correlates of hantavirus in deer mice (Peromyscus maniculatus ), we sampled 114 sites in the Walker River Basin of Nevada and California in 1995-1996. Blood samples were tested for antibody to hantavirus, and a subset of samples was also tested for virus RNA by reverse transcription-polymerase chain reaction. Average prevalence of antibody-positive mice was 17%, with

JOHN D. BOONE; ELMER W. OTTESON; KENNETH C. McGWIRE; PASCAL VILLARD; JOAN E. ROWE

1998-01-01

215

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

PubMed

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

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

2014-02-01

216

Stress-energy tensor of the quantized massive fields in Friedman-Robertson-Walker spacetimes  

NASA Astrophysics Data System (ADS)

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

Matyjasek, Jerzy; Sadurski, Pawe?

2013-11-01

217

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

PubMed

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 (R(2) > 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

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

2012-01-01

218

Mechanics and kinetics in the Friedmann-Lemaître-Robertson-Walker space-times  

NASA Astrophysics Data System (ADS)

Using the standard canonical formalism, the equations of mechanics and kinetics in the Friedmann-Lemaître-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.

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

2011-08-01

219

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

NASA Astrophysics Data System (ADS)

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

Khanal, U.

2006-07-01

220

Physical and functional evaluation in Marden-Walker syndrome: Case report - Review of literature.  

PubMed

Abstract Objective: To review literature concerning Marden-Walker syndrome (MWS) and describe physical-functional characteristics of a child with a suspected diagnosis of MWS. Methods: Physical examination, laboratory and clinical tests were collected in a two-year-old boy. Bayley Scales of Infant and Toddler Development (BSITD-III) was applied to evaluate motor-cognitive development. Results: Several facial features (blepharophimosis/micrognathia/cleft palate/pectus deformation/kyphoscoliosis), besides delayed physical growth, anemia, hypoplastic muscles, muscle atrophy and arachnodactyly were found; which are typically described in MWS. BSITD-III scaled scores were 1, 2 and 1, respectively, for gross-motor, fine-motor and cognitive skills; representing delays that were slightly more severe for gross-motor and cognitive skills compared with fine motor. We did not find joint contractures, which are strongly associated with MWS. Instead, we observed moderate muscle shortening. Conclusions: The results found could be attributed to the early intervention applied to the child since eight months old; findings that highlight the importance of early intervention. PMID:24649842

Neves Dos Santos, Adriana; Costa, Carolina Souza Neves da; de Campos, Ana Carolina; Rocha, Nelci Adriana Cicuto Ferreira

2014-08-01

221

Description and field performance of the Walker Branch throughfall displacement experiment: 1993--1996  

SciTech Connect

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.

Hanson, P.J.; Todd, D.E.; Huston, M.A. [Oak Ridge National lab., TN (United States). Environmental Sciences Div.; Joslin, J.D. [Tennessee Valley Authority, Norris, TN (United States); Croker, J.L.; Auge, R.M. [Univ. of Tennessee, Knoxville, TN (United States). Inst. of Agriculture

1998-04-01

222

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

SciTech Connect

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.

Genereux, D.; Hemond, H. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Civil Engineering; Mulholland, P. [Oak Ridge National Lab., TN (United States)

1992-05-01

223

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

PubMed

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

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

2014-05-01

224

[Concordance between vasopressin gene expression and growth of Walker 256 carcinosarcoma in rats].  

PubMed

The growth features of Walker 256 carcinosarcoma in rats of different genotypes were investigated. The experiments has been carried out on rats of the inbred Brattleboro and WAG lines, as well as on their hybrids segregated during congenic translocation of the normal vasopressin gene to the genotype of the Brattleboro rats. Brattleboro rats do not express the vasopressin gene. It has been found that there are only two types of tumor growth dynamics. In rats of the inbred Brattleboro line and in homozygotes di/di, that were segregated by backcrossings of heterozygous offsprings from the original crossbreeding between (WAG x Brattleboro) F1 x Brattleboro and the individuals with parental Brattleboro genotype, having grown to some extent the tumor regresses and disappears. In hybrid heterozygous siblings of di/+ genotype tumor grows linearly with time and always leads to fatal outcome. It has been found that, in the congenic procedure, the tumor regression trait is stably maintained and persistently inherited in lineage concordantly with the di/di genotype and, in rats with at least one allele of a normally expressed vasopressin gene, continuous and lethal tumor growth is always observed. PMID:23866631

Khega?, I I

2013-04-01

225

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

NASA Astrophysics Data System (ADS)

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-? 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.

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

2014-08-01

226

Mercury in the Walker River Basin, Nevada and California--sources, distribution, and potential effects on the ecosystem  

USGS Publications Warehouse

Mercury is one of the most serious contaminants of water, sediment, and biota in Nevada because of its use during 19th century mining activities to recover gold and silver from ores. In 1998, mercury problems were discovered in the Walker River Basin of California and Nevada when blood drawn from three common loons from Walker Lake was analyzed and found to have severely elevated mercury levels. From 1999 to 2001, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collected water, sediment, and biological samples to determine mercury sources, distribution, and potential effects on the Walker River Basin ecosystem. Total-mercury concentrations ranged from 0.62 to 57.11 ng/L in streams from the Walker River system and ranged from 1.02 to 26.8 ng/L in lakes and reservoirs. Total-mercury concentrations in streambed sediment ranged from 1 to 13,600 ng/g, and methylmercury concentrations ranged from 0.07 to 32.1 ng/g. The sediment-effects threshold for mercury for fresh-water invertebrates is 200 ng/g, which was exceeded at nine stream sites in the Walker River Basin. The highest mercury concentrations were in streams with historic mines and milling operations in the watershed. The highest mercury concentration in sediment, 13,600 ng/g, was found in Bodie Creek near Bodie, Calif., a site of extensive gold mining and milling activities during the 19th century. Sediment cores taken from Walker Lake show total-mercury concentrations exceeding 1,000 ng/g at depths greater than 15 cm below lake bottom. The presence of 137Cs above 8 cm in one core indicates that the upper 8 cm was deposited sometime after 1963. The mercury peak at 46 cm in that core, 2,660 ng/g, likely represents the peak of mining and gold extraction in the Bodie and Aurora mining districts between 1870 and 1880. Mercury concentrations in aquatic invertebrates at all sites downstream from mining activities in the Rough Creek watershed, which drains the Bodie and Aurora mining districts, were elevated (range 0.263 to 0.863 ?g/g, dry weight). Mercury concentrations in the Walker Lake tui chub, the most abundant and likely prey for common loons, ranged from approximately 0.09 ?g/g to approximately 0.9 ?g/g (wet weight). Larger tui chub in the lake, which are most likely older, had the highest mercury concentrations. Blood samples from 94 common loons collected at Walker Lake between 1998 and 2001 contained a mean mercury concentration of 2.96 ?g/g (standard deviation 1.72 ?g/g). These levels were substantially higher than those found in more than 1,600 common loons tested across North America. Among the 1,600 common loons, the greatest blood mercury concentration, 9.46 ?g/g, was from a loon at Walker Lake. According to risk assessments for northeastern North America, blood mercury concentrations exceeding 3.0 ?g/g cause behavioral, reproductive, and physiological effects. At least 52 percent of the loons at Walker Lake are at risk for adverse effects from mercury on the basis of their blood-mercury concentrations. The larger loons staging in the spring are the most at risk group. The elevated mercury levels found in tui chub and common loons indicate that there is a potential threat to the well being and reproduction of fish and wildlife that use Walker Lake. Wildlife that use Weber Reservoir may also be at risk because it is the first reservoir downstream from mining activities in the Bodie and Aurora areas and mercury concentrations in sediment were elevated. Additional data on mercury concentrations in top level predators, such as piscivorous fish and birds, are needed to assess public health and other environmental risks.

Seiler, Ralph L.; Lico, Michael S.; Wiemeyer, Evers, David C.

2004-01-01

227

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

NASA Astrophysics Data System (ADS)

The Eastern California Shear Zone (ECSZ) and Walker Lane belt (WL) accommodate ~25% of plate motion between the North American and Pacific plates. Faults within the Mina deflection link the ECSZ and the WL, transferring strain from the Owens Valley and Death Valley-Fish Lake Valley fault systems to the transcurrent faults of the central Walker Lane. During the mid to late Miocene the majority of strain between these systems was transferred through the Silver Peak-Lone Mountain (SPLM) extensional complex via a shallowly dipping detachment. Strain transfer has since primarily migrated north to the Mina Deflection; however, high-angle faults bounding sedimentary basins and discrepancies between geodetic and geologic models indicate that the SPLM complex may still actively transfer a portion of the strain from the ECSZ to the WL on a younger set of faults. Establishing the pattern and amount of active strain transfer within the SPLM region is required for a full accounting of strain accommodation, and provides insight into strain partitioning at the basin scale within a broader transtensional zone. To map the active structures in and near Clayton Valley, within the SPLM region, we collected seismic reflection and refraction profiles and a dense grid of gravity readings that were merged with existing gravity data. The primary goals were to determine the geometry of the high-angle fault system, the amount and sense of offset along each fault set, connectivity of the faults, and the relationship of these faults to the Miocene detachment. Seismic reflection profiles imaged the high-angle basin-bounding normal faults and the detachment in both the footwall and hanging wall. The extensional basin is ~1 km deep, with a steep southeastern boundary, a gentle slope to the northwest, and a sharp boundary on the northwest side, suggestive of another fault system. Two subparallel dip-slip faults bound the southeast (deeper) basin margin with a large lateral velocity change (from ~2.0 km/sec in the basin fill to 4.5-5.5 km/sec in the footwall) across the basin-bounding normal fault system. Very fast (approaching 6.0 km/sec) basement underlies the basin fill. The residual gravity anomaly indicates that Clayton Valley is divided into a shallower northern basin, imaged by the seismic lines, and a deeper, more asymmetric southern basin. Faults within Clayton Valley are curvilinear in nature, similar to faults observed in other step-over systems (e.g., the Mina Deflection). Gravity profiles support the seismic reflection interpretation and indicate a high angle fault (>60 degrees) bounding the northern sub-basin on its southeast margin, with a shallower fault bounding it to the northwest. A basement high trends west-northwest and separates the northern and southern basins, and is likely bounded on its southern edge by a predominantly strike-slip fault crossing the valley. Much of the strain accommodated within the southern sub-basin appears to be transferred into southern Big Smoky Valley, northwest of Clayton Valley, via these dextral strike-slip faults that obliquely cross Clayton Valley.

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

2011-12-01

228

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

PubMed Central

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.

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

2013-01-01

229

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

PubMed

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

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

2011-11-01

230

POMT2 mutations cause ?-dystroglycan hypoglycosylation and Walker-Warburg syndrome  

PubMed Central

Background: Walker-Warburg syndrome (WWS) is an autosomal recessive condition characterised by congenital muscular dystrophy, structural brain defects, and eye malformations. Typical brain abnormalities are hydrocephalus, lissencephaly, agenesis of the corpus callosum, fusion of the hemispheres, cerebellar hypoplasia, and neuronal overmigration, which causes a cobblestone cortex. Ocular abnormalities include cataract, microphthalmia, buphthalmos, and Peters anomaly. WWS patients show defective O-glycosylation of ?-dystroglycan (?-DG), which plays a key role in bridging the cytoskeleton of muscle and CNS cells with extracellular matrix proteins, important for muscle integrity and neuronal migration. In 20% of the WWS patients, hypoglycosylation results from mutations in either the protein O-mannosyltransferase 1 (POMT1), fukutin, or fukutin related protein (FKRP) genes. The other genes for this highly heterogeneous disorder remain to be identified. Objective: To look for mutations in POMT2 as a cause of WWS, as both POMT1 and POMT2 are required to achieve protein O-mannosyltransferase activity. Methods: A candidate gene approach combined with homozygosity mapping. Results: Homozygosity was found for the POMT2 locus at 14q24.3 in four of 11 consanguineous WWS families. Homozygous POMT2 mutations were present in two of these families as well as in one patient from another cohort of six WWS families. Immunohistochemistry in muscle showed severely reduced levels of glycosylated ?-DG, which is consistent with the postulated role for POMT2 in the O-mannosylation pathway. Conclusions: A fourth causative gene for WWS was uncovered. These genes account for approximately one third of the WWS cases. Several more genes are anticipated, which are likely to play a role in glycosylation of ?-DG.

van Reeuwijk, J; Janssen, M; van den Elzen, C; d Beltran-Valero; Sabatelli, P; Merlini, L; Boon, M; Scheffer, H; Brockington, M; Muntoni, F; Huynen, M; Verrips, A; Walsh, C; Barth, P; Brunner, H; van Bokhoven, H

2005-01-01

231

A taxonomic revision of the genus Edosa Walker, 1886 from China (Lepidoptera, Tineidae, Perissomasticinae).  

PubMed

The genus Edosa Walker, 1886 is revised in China. Of the 31 recognized species, 23 are described as new: Edosa aurea sp. nov., E. baculiformis sp. nov., E. bicolor sp. nov., E. bifurcata sp. nov., E. carinata sp. nov., E. conchata sp. nov., E. cornuta sp. nov., E. curvidorsalis sp. nov., E. dentata sp. nov., E. digitata sp. nov., E. duoprojecta sp. nov., E. elongata sp. nov., E. eminens sp. nov., E. hamata sp. nov., E. longicornis sp. nov., E. minuta sp. nov., E. robinsoni sp. nov., E. robustispina sp. nov., E. semicircularis sp. nov., E. torta sp. nov., E. truncatula sp. nov., E. uncusella sp. nov., and E. varians sp. nov.; Edosa gaedikei nom. nov. is proposed as a replacement name for Edosa spinosa Gaedike, 2012, a junior homonym of Edosa spinosa Gaedike, 1984; four species are newly recorded for China: E. hendrixella Robinson, 2008, E. crayella Robinson, 2008, E. orphnodes (Meyrick, 1911) and E. smithaella Robinson, 2008; the female of E. hendrixella is described for the first time. Phylogenetic relationships of the Chinese species, except E. malthacopis (Meyrick, 1936), are postulated based on 42 morphological characters. The phylogenetic analysis of the morphology matrix yielded one most parsimonious tree (length 121 steps, CI = 0.56, RI = 0.81), based on which seven species-groups are proposed: the hemichrysella-group, the subochraceella-group, the pyrochra-group, the duoprojecta-group, the eminens-group, the crayella-group and the uncusella-group. The whole body structures of the genus are presented and photographs of adults and genitalia are provided, along with a key to all the known Chinese species and maps to show the distribution of Edosa in China. A world checklist of Edosa is given as an appendix, in which 41 new combinations are included. PMID:24871620

Yang, Linlin; Wang, Shuxia; Li, Houhun

2014-01-01

232

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

PubMed

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

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

2011-01-01

233

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

NASA Technical Reports Server (NTRS)

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.

Robertson, Franklin; Bosilovich, Michael; Miller, Timothy

2007-01-01

234

Synthesis and insecticidal activity of novel hydrazone compounds derived from a naturally occurring lignan podophyllotoxin against Mythimna separata (Walker).  

PubMed

In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of novel hydrazone derivatives of podophyllotoxin, which is a naturally occurring aryltetralin lignan and isolated as the main secondary metabolite from the roots and rhizomes of Podophyllum species, were synthesized and evaluated as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. Especially compounds 8i, 8j, 8t, and 8u showed the more potent insecticidal activity with the final mortality rates greater than 60%. PMID:24810569

Wang, Yi; Yu, Xiang; Zhi, Xiaoyan; Xiao, Xiao; Yang, Chun; Xu, Hui

2014-06-15

235

Promoting step responses of children with multiple disabilities through a walker device and microswitches with contingent stimuli.  

PubMed

Children with severe or profound intellectual and motor disabilities often present problems of balance and locomotion and spend much of their time sitting or lying, with negative consequences for their development and social image. This study provides a replication of recent (pilot) studies using a walker (support) device and microswitches with preferred stimuli to promote locomotion in two children with multiple disabilities. One child used an ABAB design; the other only an AB sequence. Both succeeded in increasing their frequencies of step responses during the B (intervention) phase(s). These findings support the positive evidence already available on the effectiveness of this intervention in motivating and promoting children's locomotion. PMID:18986038

Lancioni, G E; De Pace, C; Singh, N N; O'Reilly, M F; Sigafoos, J; Didden, R

2008-08-01

236

Impact of favorite stimuli automatically delivered on step responses of persons with multiple disabilities during their use of walker devices.  

PubMed

Favorite stimuli were automatically delivered contingent on the performance of steps by two persons (a boy and a woman) with multiple disabilities during their use of support walker devices. The study lasted about 4 months and was carried out according to a multiple baseline design across participants. Recording concerned the participants' frequencies of steps and their indices of happiness during baseline and intervention sessions. Data showed that both participants had a significant increase in each of these two measures during the intervention phase. Implications of the findings and new research issues are discussed. PMID:15590239

Lancioni, Giulio E; Singh, Nirbhay N; O'Reilly, Mark F; Campodonico, Francesca; Piazzolla, Giorgia; Scalini, Lorenza; Oliva, Doretta

2005-01-01

237

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

NASA Astrophysics Data System (ADS)

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.

Kim, Sang Pyo

1992-10-01

238

Two different regimes of anomalous walker circulation over the Indian and Pacific Oceans before and after the late 1970s  

NASA Astrophysics Data System (ADS)

Using the National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data aided by a coupled ocean-atmosphere model, we investigated two different regimes of anomalous Walker circulation system over the Pacific and Indian Oceans before and after a climate shift, which occurred in the late 1970s. During the period before the climate shift, an upper-level velocity potential anomaly systematically moves eastward from the tropical Indian Ocean to the warm pool region of the western Pacific during the growth phase of El Niño-Southern Oscillation (ENSO). In the meantime, the activities of South Asian and Australian summer monsoon systems are directly affected by the evolution of the anomalous Walker circulation. During the period after the climate shift, in contrast, an upperlevel velocity potential anomaly in the vicinity of the Philippine Sea and maritime continent is observed to expand westward into the northern Indian Ocean and South Asia during the decay phase of ENSO. This feature is identified with a major precursory signal of an anomalous South Asian summer monsoon in the preceding spring. The model captures a systematic eastward propagation similar to that observed prior to the late 1970s, but fails to reproduce the westward extension of the velocity potential anomaly observed to prevail after the late 1970s. The model results suggest that the cross-basin connection between the two oceans is a prerequisite for the turnabout of ENSO prior to the climate shift, in terms of the occurrence of westerly wind bursts.

Kawamura, Ryuichi; Aruga, Hiromitsu; Matsuura, Tomonori; Iizuka, Satoshi

239

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

NASA Astrophysics Data System (ADS)

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.

Waldien, T.

2012-12-01

240

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

NASA Astrophysics Data System (ADS)

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.

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

2006-11-01

241

Block Modeling of Crustal Deformation in the Northern Walker Lane, Western Basin and Range, to Improve Estimates of Seismic Hazard  

NASA Astrophysics Data System (ADS)

In the United States, seismic hazard is evaluated officially by the U.S. Geological Survey and published as estimates in the National Seismic Hazard Maps (NSHM) that depict the peak ground shaking at a specific level of likelihood. In the western Great Basin, the 2002 NSHM is based on a combination of seismic, geologic and geodetic data. However, a discrepancy between the deformation rate that is inferred from the geodetic data (e.g. GPS) and geologic data (e.g. slip rates from fault studies) led to the introduction of an ad hoc zone of crustal shear strain in the western Basin and Range. Only then was the shaking risk portrayed in the NSHM consistent with the relative geodetic velocity of the Sierra Nevada microplate with respect to the central Great Basin. Since creation of the 2002 NSHM there has been a rapid increase in the quantity, quality and spatial coverage of GPS data in the western Great Basin, providing a vast improvement on the constraint on the pattern of crustal deformation. Thus geodesy is poised to make a substantial contribution to the spatial localization of seismic hazard in support of the next generation NSHM. In the Walker Lane ~10 mm/yr of relative motion are accommodated as shear and extension along a ~200 km wide and ~1000 km long zone of intracontinental deformation associated with the Pacific/North American plate boundary. We integrate GPS velocities obtained from sites in the continuous BARGEN, PBO, BARD, semi-continuous MAGNET network plus campaign results from numerous published results to constrain block models of crustal deformation. In so doing we estimate slip rates on block-bounding faults that have regional kinematic self-consistency and can be easily incorporated into the USGS algorithms that compute estimates for seismic hazard. Because of the large number and high density of candidate faults, and length of this zone we divide the region into three parts covering the Northern, Central and Southern Walker Lane. We have completed building the models for the northern Walker Lane (latitude 38.5 to 40.5 degrees, longitude - 120 to -117 degrees) and will present results from this section. The model has 62 blocks with mean dimension of ~30 km on a side, and thus the blocks are small compared to the width of the expected signal owing to elastic strain accumulation across locked faults. This starting number of blocks is purposefully large. We will discuss the ability that the data have to resolve details in the pattern of crustal deformation, and make a special effort to quantify the uncertainties and trade-offs in slip rates of nearby faults whose strain signals can overlap.

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

2007-05-01

242

March 17 - 19, 2004: caBIG CDE/V Kickoff Meeting Presentation, Daniel E. Geraghty, Heather Kincaid, Derek Walker, Rahul Joshi, Robert Robbins, Mark Thornquist  

Cancer.gov

caBIG CDE/V Kickoff Me eting Presentation Fred Hutchinson Cancer Research Center caBIG CDE/V Kickoff Meeting Presentation Fred Hutchinson Cancer Research Center Daniel E. Geraghty, Heather Kincaid, Derek Walker, Rahul Joshi, Robert Robbins, Mark Thornquist.

243

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

Microsoft Academic Search

The effect of coconut fat (rich in medium saturated fatty acids) or fish oil (rich in -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

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

2007-01-01

244

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)

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.

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

2011-12-01

245

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

NASA Astrophysics Data System (ADS)

The Walker Lane is a 100 km-wide distributed zone of complex transtensional faulting that flanks the eastern margin of the Sierra Nevada. Up to 25% of the total Pacific-North American relative right-lateral plate boundary deformation is accommodated east of the Sierra Nevada, primarily in the Walker Lane. The results of three studies in the Central and Northern Walker Lane offer new insights into how constantly accumulating plate boundary shear strain is released on faults in the Walker Lane and regional earthquake hazards. This research is based on the collection and analysis of new of geologic and geodetic datasets. Two studies are located in the Central Walker Lane, where plate boundary deformation is accommodated on northwest trending right-lateral faults, east-northeast trending left-lateral faults, and north trending normal faults. In this region, a prominent set of left-stepping, en-echelon, normal fault-bounded basins between Walker Lake and Lake Tahoe fill a gap in Walker Lane strike slip faults. Determining how these basins accommodate shear strain is a primary goal of this research. Paleoseismic and neotectonic observations from the Wassuk Range fault zone in the Walker Lake basin record evidence for at least 3 Holocene surface rupturing earthquakes and Holocene/late Pleistocene vertical slip rates between 0.4-0.7 mm/yr on the normal fault, but record no evidence of right-lateral slip along the rangefront fault. A complementary study presents new GPS velocity data that measures present-day deformation across the Central Walker Lane and infers fault slip and block rotation rates using an elastic block model. The model results show a clear partitioning between distinct zones of strain accommodation characterized by (1) right-lateral translation of blocks on northwest trending faults, (2) left-lateral slip and clockwise block rotations between east and northeast trending faults, and (3) right-lateral oblique normal slip with minor clockwise block rotations on north trending faults. Block model results show that a component of right-lateral slip in the normal-fault bounded basins is required to adequately fit the GPS data. New GPS data from the Northern Walker Lane constrains present-day slip rates on the Mohawk Valley, Grizzly Valley, and Honey Lake fault zones. Block model results predict right-lateral slip rates of 2.2 +/- 0.2 mm/yr for the Mohawk Valley fault and 1.1 +/- 0.4 mm/yr for the Honey Lake fault. The GPS data do not require slip on the Grizzly Valley fault, although right-lateral slip rates up to 1.2 mm/yr are allowed without increasing the block model misfit. The present-day distribution of slip between the Honey Lake and Mohawk Valley faults is opposite that predicted by latest Quaternary and Holocene geologic slip rate estimates. A temporally variable Wallace-type strain release model that includes 104-year timescale variations in fault slip rate could reconcile both datasets.

Bormann, Jayne M.

246

Dandy-Walker Malformation and Down Syndrome Association: Good Developmental Outcome and Successful Endoscopic Treatment of Hydrocephalus  

PubMed Central

The association of Down syndrome (DS) with Dandy Walker malformation (DWM) is extremely rare, with only 3 cases reported to date. All cases reported have shown a bad life expectancy and a bad developmental outcome. The present case reveals the possibility of a good prognosis. A 19-month-old male patient had successful endoscopic hydrocephalus treatment and a good developmental outcome. He probably had a better outcome because of good DS and DWM prognostic parameters. Our patient suffered from a DWM with vermis identification of 2 fissures and 3 lobes and a DS with a well-preserved tonus, which was not associated with other congenital systemic defects. We may conclude that the prognosis of DS-DWM association may separately depend on the degree of clinical and neurological involvement of each malformation.

Nigri, Flavio; Cabral, Isaias Fiuza; da Silva, Raquel Tavares Boy; Pereira, Heloisa Viscaino; Ribeiro, Carlos Roberto Telles

2014-01-01

247

Analog model of a Friedmann-Robertson-Walker universe in Bose-Einstein condensates: Application of the classical field method  

SciTech Connect

Analog models of gravity have been motivated by the possibility of investigating phenomena not readily accessible in their cosmological counterparts. In this paper, we investigate the analog of cosmological particle creation in a Friedmann-Robertson-Walker universe by numerically simulating a Bose-Einstein condensate with a time-dependent scattering length. In particular, we focus on a two-dimensional homogeneous condensate using the classical field method via the truncated Wigner approximation. We show that for various forms of the scaling function the particle production is consistent with the underlying theory in the long wavelength limit. In this context, we further discuss the implications of modified dispersion relations that arise from the microscopic theory of a weakly interacting Bose gas.

Jain, Piyush; Weinfurtner, Silke; Visser, Matt; Gardiner, C. W. [School of Chemical and Physical Sciences, Victoria University of Wellington (New Zealand); School of Mathematics, Statistics, and Computer Science, Victoria University of Wellington (New Zealand); Jack Dodd and Dan Walls Centre for Photonics and Ultra Cold Atoms, Department of Physics, Otago University, Dunedin (New Zealand)

2007-09-15

248

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

NASA Astrophysics Data System (ADS)

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

Biholar, Alexander Kenneth Casian

249

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

USGS Publications Warehouse

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.

Briggs, Richard W.; Hammond, William C.

2010-01-01

250

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

SciTech Connect

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.

Donahue, M.L. [Medical Univ. of South Carolina, Charleston, SC (United States); Ryan, R.M. [Univ. of Rochester, NY (United States)

1995-03-13

251

Quantization of Friedmann-Robertson-Walker Spacetimes in the Presence of a Cosmological Constant and Stiff Matter  

NASA Astrophysics Data System (ADS)

In the present work, we study the quantum cosmology description of two Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a negative cosmological constant. The models differ from each other by the constant curvature of the spatial sections, taken to be either positive or zero. We work in the Schutz's variational formalism, quantizing the models and obtaining the appropriate Wheeler-DeWitt equations. In these models there are bound states. Therefore, we compute, for each one, the discrete energy spectrum and the corresponding eigenfunctions. After that, we use the eigenfunctions in order to construct wave packets and evaluate the time-dependent expectation values of the scale factors. Each model shows bounded oscillations for the expectation value of the scalar factor, which is never zero, which can be interpreted as an initial indication that these models may not have singularities at the quantum level.

Oliveira-Neto, G.; Monerat, G. A.; Corrêa Silva, E. V.; Neves, C.; Ferreira Filho, L. G.

2013-09-01

252

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

253

Dandy-walker malformation and down syndrome association: good developmental outcome and successful endoscopic treatment of hydrocephalus.  

PubMed

The association of Down syndrome (DS) with Dandy Walker malformation (DWM) is extremely rare, with only 3 cases reported to date. All cases reported have shown a bad life expectancy and a bad developmental outcome. The present case reveals the possibility of a good prognosis. A 19-month-old male patient had successful endoscopic hydrocephalus treatment and a good developmental outcome. He probably had a better outcome because of good DS and DWM prognostic parameters. Our patient suffered from a DWM with vermis identification of 2 fissures and 3 lobes and a DS with a well-preserved tonus, which was not associated with other congenital systemic defects. We may conclude that the prognosis of DS-DWM association may separately depend on the degree of clinical and neurological involvement of each malformation. PMID:24932176

Nigri, Flavio; Cabral, Isaias Fiuza; da Silva, Raquel Tavares Boy; Pereira, Heloisa Viscaíno; Ribeiro, Carlos Roberto Telles

2014-05-01

254

Decreased anterior pituitary T3 nuclear receptors in a Walker 256 carcinoma-bearing rat model of nonthyroidal disease.  

PubMed

Rats bearing the Walker 256 carcinoma have decreased pituitary nuclear T3 but normal pituitary TSH content and response to experimental hypothyroidism. To elucidate further the role of T3 receptor occupancy and biological response in the tumor-bearing rat model of nonthyroidal disease, we measured the concentration of T3 nuclear receptors, rTSH and rGH and beta-TSH mRNA and GH mRNA in the anterior pituitary of euthyroid rats bearing the Walker 256 carcinoma. The abundance of T3 nuclear receptors was decreased in tumor-bearing rats and was associated with a decrease in mRNA content for beta-TSH and GH. alpha-tubulin mRNA was decreased to a comparable degree. The pituitary content of rTSH and rGH was, however, the same as in control animals. Since tumor rats have normal regulation of TSH secretion by thyroid hormone, the present findings suggest that TSH secretion in T rats is maintained by a lower T3 nuclear receptor occupancy than in controls. The decrease in beta-TSH mRNA may precede a decrease in TSH synthesis and changes in pituitary TSH stores. Since the decrease in GH mRNA was comparable to the decrease in alpha-tubulin mRNA, it does not appear to be specifically related to decreased T3 nuclear receptor occupancy. We conclude that, in the tumor-bearing rat model of nonthyroidal disease, decreases in beta-TSH mRNA occur despite a decreased T3 receptor occupancy. Both thyroid-dependent and thyroid-independent factors may be involved in regulating beta-TSH mRNA. PMID:2609901

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

1989-12-01

255

Asymmetric ferromagnetic resonance, universal Walker breakdown, and counterflow domain wall motion in the presence of multiple spin-orbit torques  

NASA Astrophysics Data System (ADS)

We study the motion of several types of domain wall profiles in spin-orbit coupled magnetic nanowires and also the influence of spin-orbit interaction on the ferromagnetic resonance of uniform magnetic films. Whereas domain wall motion in systems without correlations between spin space and real space is not sensitive to the precise magnetization texture of the domain wall, spin-orbit interactions break the equivalence between such textures due to the coupling between the momentum and spin of the electrons. In particular, we extend previous studies by fully considering not only the fieldlike contribution from the spin-orbit torque, but also the recently derived Slonczewski-like spin-orbit torque. We show that the latter interaction affects both the domain wall velocity and the Walker breakdown threshold nontrivially, which suggests that it should be accounted for in experimental data analysis. We find that the presence of multiple spin-orbit torques may render the Walker breakdown universal in the sense that the threshold is completely independent on the material-dependent Gilbert damping ?, nonadiabaticity ?, and the chirality ? of the domain wall. We also find that domain wall motion against the current injection is sustained in the presence of multiple spin-orbit torques and that the wall profile will determine the qualitative influence of these different types of torques (e.g., fieldlike and Slonczewski-like). In addition, we consider a uniform ferromagnetic layer under a current bias, and find that the resonance frequency becomes asymmetric against the current direction in the presence of Slonczewski-like spin-orbit coupling. This is in contrast with those cases where such an interaction is absent, where the frequency is found to be symmetric with respect to the current direction. This finding shows that spin-orbit interactions may offer additional control over pumped and absorbed energy in a ferromagnetic resonance setup by manipulating the injected current direction.

Linder, Jacob; Alidoust, Mohammad

2013-08-01

256

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

PubMed

The goal of this study is to describe accurately how the directional information given by support inclinations affects the ant Lasius niger motion in terms of a behavioral decision. To this end, we have tracked the spontaneous motion of 345 ants walking on a 0.5×0.5 m plane canvas, which was tilted with 5 various inclinations by [Formula: see text] rad ([Formula: see text] data points). At the population scale, support inclination favors dispersal along uphill and downhill directions. An ant's decision making process is modeled using a version of the Boltzmann Walker model, which describes an ant's random walk as a series of straight segments separated by reorientation events, and was extended to take directional influence into account. From the data segmented accordingly ([Formula: see text] segments), this extension allows us to test separately how average speed, segments lengths and reorientation decisions are affected by support inclination and current walking direction of the ant. We found that support inclination had a major effect on average speed, which appeared approximately three times slower on the [Formula: see text] incline. However, we found no effect of the walking direction on speed. Contrastingly, we found that ants tend to walk longer in the same direction when they move uphill or downhill, and also that they preferentially adopt new uphill or downhill headings at turning points. We conclude that ants continuously adapt their decision making about where to go, and how long to persist in the same direction, depending on how they are aligned with the line of maximum declivity gradient. Hence, their behavioral decision process appears to combine klinokinesis with geomenotaxis. The extended Boltzmann Walker model parameterized by these effects gives a fair account of the directional dispersal of ants on inclines. PMID:24204636

Khuong, Anaïs; Lecheval, Valentin; Fournier, Richard; Blanco, Stéphane; Weitz, Sébastian; Bezian, Jean-Jacques; Gautrais, Jacques

2013-01-01

257

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)

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.

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

2006-12-01

258

CICLO DE VIDA Y TASAS DE SUPERVIVENCIA Y REPRODUCCIÓN DE Copitarsia incommoda WALKER (LEPIDOPTERA: NOCTUIDAE) EN TRES CULTIVARES DE Brassica oleracea L. LIFE CYCLE AND SURVIVAL AND REPRODUCTION RATES OF Copitarsia incommoda WALKER (LEPIDOPTERA: NOCTUIDAE) IN THREE CULTIVARS OF Brassica oleracea L  

Microsoft Academic Search

This research was carried out to know the biological cycle and the survival and reproduction rates of Copitarsia incommoda, previously known as Copitarsia consueta (Walker) (Angulo and Olivares, 2003), in three different cultivars of Brassica oleracea L., crops on which this species feeds. For this purpose, the demographic technique of life and reproduction tables was used. The study allowed to

Leonardo Flores-Pérez; Néstor Bautista-Martínez; Jorge Vera-Graziano; Jorge Valdez-Carrasco; Andrés O. Angulo; Especialidad en Entomología

259

Analytic expression for the mean time to absorption for a random walker on the Sierpinski fractal. III. The effect of non-nearest-neighbor jumps  

NASA Astrophysics Data System (ADS)

We present exact, analytic results for the mean time to trapping of a random walker on the class of deterministic Sierpinski graphs embedded in d?2 Euclidean dimensions, when both nearest-neighbor (NN) and next-nearest-neighbor (NNN) jumps are included. Mean first-passage times are shown to be modified significantly as a consequence of the fact that NNN transitions connect fractals of two consecutive generations.

Balakrishnan, V.; Kozak, John J.

2013-11-01

260

Style of deformation along the Death Valley-Furnace Creek fault zone and other faults in the southern Walker Lane, Nevada and California  

Microsoft Academic Search

Quaternary normal and right-lateral faults and associated lineaments in the southern part of the Walker Lane are anomalous with respect to the north-striking normal faults in most of the central Great Basin. The authors identify and characterize many faults and lineaments that were previously unmapped, with the exception of faults in the Death Valley-Furnace Creek fault zone (DVFCFZ) and some

J. S. Noller; M. C. Reheis

1993-01-01

261

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

Microsoft Academic Search

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

Cassandre Labelle-Dumais; David J. Dilworth; Emily P. Harrington; Michelle de Leau; David Lyons; Zhyldyz Kabaeva; M. Chiara Manzini; William B. Dobyns; Christopher A. Walsh; Daniel E. Michele; Douglas B. Gould

2011-01-01

262

Extracellular matrix and nuclear abnormalities in skeletal muscle of a patient with Walker–Warburg syndrome caused by POMT1 mutation  

Microsoft Academic Search

Walker–Warburg syndrome (WWS) is an autosomal recessive disorder characterized by congenital muscular dystrophy, structural eye abnormalities and severe brain malformations. We performed an immunohistochemical and electron microscopy study of a muscle biopsy from a patient affected by WWS carrying a homozygous frameshift mutation in O-mannosyltransferase 1 gene (POMT1). ?-Dystroglycan glycosylated epitope was not detected in muscle fibers and intramuscular peripheral

Patrizia Sabatelli; Marta Columbaro; Isabella Mura; Cristina Capanni; Giovanna Lattanzi; Nadir M. Maraldi; Daniel Beltràn-Valero de Barnabè; Hans van Bokoven; Stefano Squarzoni; Luciano Merlini

2003-01-01

263

First report of a trichomycete fungus (Zygomycota: Trichomycetes) inhabiting larvae of Simulium ochraceum sensu lato Walker (Diptera: Simuliidae) from the Galapagos Islands  

Microsoft Academic Search

A collection of the larval black fly Simulium ochraceum sensu lato Walker was made at six lotic habitats on San Cristobal Island, Galapagos Islands, Ecuador, during May 2003. Sixty-eight larvae were assayed for the presence of gut fungi (Zygomycota: Trichomycetes). A trichomycete, designated as Smittium sp. was found inhabiting the hindgut of 17.6% of S. ochraceum s.l. larvae. Implications of

Mark P. Nelder; John W. McCreadie; Cecilia Coscarón; Charles L. Brockhouse

2004-01-01

264

Data on ground-water quality for the Walker Lake 1 degree x 2 degree quadrangle, western Nevada and eastern California  

USGS Publications Warehouse

Water quality data for groundwater has been compiled for the Walker Lake 1 degree x 2 degree quadrangle which covers a portion of western Nevada and eastern California. Chemical characteristics of the water are shown on a map (at a scale of 1:250,000) and on trilinear diagrams for the major ions. The data for the area are also presented in a table. (USGS)

Welch, Alan H.; Williams, Rhea P.

1987-01-01

265

Characterisation of Walker 256 breast carcinoma cells from two tumour cell banks as assessed using two models of secondary brain tumours  

PubMed Central

Background Metastatic brain tumours are a common end stage of breast cancer progression, with significant associated morbidity and high mortality. Walker 256 is a rat breast carcinoma cell line syngeneic to Wistar rats and commonly used to induce secondary brain tumours. Previously there has been the assumption that the same cancer cell line from different cell banks behave in a similar manner, although recent studies have suggested that cell lines may change their characteristics over time in vitro. Methods In this study internal carotid artery injection and direct cerebral inoculation models of secondary brain tumours were used to determine the tumorigenicity of Walker 256 cells obtained from two cell banks, the American Type Culture Collection (ATCC), and the Cell Resource Centre for Medical Research at Tohoku University (CRCTU). Results Tumour incidence and volume, plus immunoreactivity to albumin, IBA1 and GFAP, were used as indicators of tumorigenicity and tumour interaction with the host brain microenvironment. CRCTU Walker 256 cells showed greater incidence, larger tumour volume, pronounced blood–brain barrier disruption and prominent glial response when compared to ATCC cell line. Conclusions These findings indicate that immortalised cancer cell lines obtained from different cell banks may have diverse characteristics and behaviour in vivo.

2013-01-01

266

Does freezing and dynamic flexing of frozen branches impact the cavitation resistance of Malus domestica and the Populus clone Walker?  

PubMed

Frost damage to the xylem conduits of trees is a phenomenon of eco-physiological importance. It is often documented in terms of the percentage loss of conductivity (PLC), an indicator of air filling of the conduits. However, trees that refill their conduits in spring could be impacted more by damage to the conduits that reduce cavitation resistance, making them more susceptible to future drought events. We investigated whether ice formation, dynamic flexing of frozen branches or freeze-thaw events could reduce the cavitation resistance (cause "frost fatigue") in first-year shoots of apple (Malus domestica) and clonal hybrid cottonwood (Walker). Frost fatigue was measured in terms of P50 (the negative xylem pressure required to cause a 50 % loss of conductivity). All treatment groups showed significant frost fatigue, with the exception of the pre-flushed, constantly frozen poplar branches. The P50 following freeze treatments was approximately 50 % of the pre-freeze values. The effect tended to be greater in freeze-thawed branches. Dynamic bending of the branches had no effect on either PLC or P50. In three out of four cases, there was a significant correlation between P50 and PLC. Frost fatigue occurred in both apple and poplar, two unrelated species with different drought and frost tolerances, suggesting that it may be a widespread phenomenon that could impact the ecophysiology of temperate forests. PMID:23624704

Christensen-Dalsgaard, Karen K; Tyree, Melvin T

2013-11-01

267

Sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker) (Lepidoptera: Lymantriidae).  

PubMed

Two distinct electroantennographycally active (EAG-active) components, A and B, and a weakly active component C were found in a solvent extract from virgin females of the Ishigaki strain of the tussock moth, Orgyia postica (Walker). Components A, B, and C were found in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively. Components A, B, and C were identified as (6Z,9Z,11S,12S)-11,12-epoxyhenicosa-6,9-diene [(11S,12S)-1: posticlure], (6Z)-henicos-6-en-11-one (2), and (6Z,9Z)-henicosa-6,9-diene (3), respectively. Component B was absent in the extract from the Okinawa strain, in which components A and C were present at 2.0 and 1.5 ng/female respectively. (11S,12S)-1 and the racemic mixture showed attractiveness for both the Okinawa and Ishigaki strains, whereas (11R,12R)-1 did not. The addition of 2 significantly reduced the trap catches with (11S,12S)-1 on the Okinawa strain which lacked 2, while there was no significant inhibitory effect on the Ishigaki strain. The addition of 3 to (11S,12S)-1 did not significantly affect trap catches at Ishigaki or Okinawa. This confirmed that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1. PMID:15914916

Wakamura, Sadao; Arakaki, Norio; Yamamoto, Masanobu; Hiradate, Syuntaro; Yasui, Hiroe; Kinjo, Kunio; Yasuda, Tetsuya; Yamazawa, Hiroyuki; Ando, Tetsu

2005-05-01

268

160 kb deletion in ISPD unmasking a recessive mutation in a patient with Walker-Warburg syndrome.  

PubMed

Walker-Warburg syndrome (WWS) is a severe muscular dystrophy with eye and brain malformations. On a molecular level, WWS is a disorder of the O-linked glycosylation of ?-dystroglycan and therefore referred to as one of the dystroglycanopathies. The disease family of muscular dystrophy-dystroglycanopathy (MDDG) contains a spectrum of severe to mild disorders, designated as MDDG type A to C. WWS, as the most severe manifestation, corresponds to MDDG type A. Defects in the genes POMT1, POMT2, POMGNT1, FKTN, FKRP, LARGE, GTDC2, G3GALNT2, GMPPB, B3GNT1, TMEM5 and COL4A1 and ISPD have been described as causal for several types of MDDG including WWS, but can only be confirmed in about 60-70% of the clinically diagnosed individuals. The proteins encoded by these genes are involved in the posttranslational modification of ?-dystroglycan. Mutations in POMT1, POMT2, POMGNT1, FKTN, FKRP, LARGE, GMPPB, TMEM5 and COL4A1 and ISPD lead to a wide spectrum of phenotypes of congenital muscular dystrophies with or without eye and brain abnormalities. Patients with WWS frequently demonstrate a complete lack of psychomotor development, severe eye malformations, cobblestone lissencephaly and a hypoplastic cerebellum and brainstem, seizures, hydrocephalus and poor prognosis. Here, we present a boy with WWS who showed compound heterozygous changes in ISPD and discuss the clinical and radiological phenotype and the molecular genetic findings, including a novel pathogenic mutation in ISPD. PMID:24120487

Czeschik, Johanna Christina; Hehr, Ute; Hartmann, Britta; Lüdecke, Hermann-Josef; Rosenbaum, Thorsten; Schweiger, Bernd; Wieczorek, Dagmar

2013-12-01

269

Exome Sequencing and Functional Validation in Zebrafish Identify GTDC2 Mutations as a Cause of Walker-Warburg Syndrome  

PubMed Central

Whole-exome sequencing (WES), which analyzes the coding sequence of most annotated genes in the human genome, is an ideal approach to studying fully penetrant autosomal-recessive diseases, and it has been very powerful in identifying disease-causing mutations even when enrollment of affected individuals is limited by reduced survival. In this study, we combined WES with homozygosity analysis of consanguineous pedigrees, which are informative even when a single affected individual is available, to identify genetic mutations responsible for Walker-Warburg syndrome (WWS), a genetically heterogeneous autosomal-recessive disorder that severely affects the development of the brain, eyes, and muscle. Mutations in seven genes are known to cause WWS and explain 50%–60% of cases, but multiple additional genes are expected to be mutated because unexplained cases show suggestive linkage to diverse loci. Using WES in consanguineous WWS-affected families, we found multiple deleterious mutations in GTDC2 (also known as AGO61). GTDC2’s predicted role as an uncharacterized glycosyltransferase is consistent with the function of other genes that are known to be mutated in WWS and that are involved in the glycosylation of the transmembrane receptor dystroglycan. Therefore, to explore the role of GTDC2 loss of function during development, we used morpholino-mediated knockdown of its zebrafish ortholog, gtdc2. We found that gtdc2 knockdown in zebrafish replicates all WWS features (hydrocephalus, ocular defects, and muscular dystrophy), strongly suggesting that GTDC2 mutations cause WWS.

Manzini, M. Chiara; Tambunan, Dimira E.; Hill, R. Sean; Yu, Tim W.; Maynard, Thomas M.; Heinzen, Erin L.; Shianna, Kevin V.; Stevens, Christine R.; Partlow, Jennifer N.; Barry, Brenda J.; Rodriguez, Jacqueline; Gupta, Vandana A.; Al-Qudah, Abdel-Karim; Eyaid, Wafaa M.; Friedman, Jan M.; Salih, Mustafa A.; Clark, Robin; Moroni, Isabella; Mora, Marina; Beggs, Alan H.; Gabriel, Stacey B.; Walsh, Christopher A.

2012-01-01

270

Investigation of a potential force-generation machinery driven by a cytoskeletal Walker-type ATPase in prokaryotic cells  

NASA Astrophysics Data System (ADS)

Cytoskeletal proteins are often involved in generating mechanical force to drive various cellular processes. A subgroup of the Walker-type ATPases acts as cytoskeletal proteins that show highly dynamic behavior in bacterial cells. One of the most prominent examples is MinD that works with other cellular components to prevent cell division at unwanted polar sites through cycles of pole-to-pole oscillation in E. coli cells. We use fluorescence microscopy techniques to study the process of MinD assembly and disassembly on a lipid bilayer membrane surface and any possible change of membrane properties caused by MinD association with the membrane. To form a supported bilayer membrane, vesicles of the polar or total extract of E. coli membrane or synthetic lipids of defined composition are adsorbed to a treated glass coverslip. Ca^2+ is added to enable vesicle fusion to form a continuous bilayer on a glass surface. Formation of a bilayer is examined using fluorescence recovery after photobleaching. The results on the protein assembly on membranes present an important step in understanding the intermediate stages that occur during the dynamic movement of MinD in cells.

Erbe, Andeas; Hou, Sing-Yi; Chen, Chen-Yun; Lin, Yi-Lih; Shen, Jie-Pan; Lin, Li-Jing; Chou, Chia-Fu; Shih, Yu-Ling

2008-03-01

271

Exploring the Midgut Transcriptome and Brush Border Membrane Vesicle Proteome of the Rice Stem Borer, Chilo suppressalis (Walker)  

PubMed Central

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.

Peng, Chuanhua; Wang, Xiaoping; Li, Fei; Lin, Yongjun

2012-01-01

272

Is Dandy-Walker malformation associated with "distal 13q deletion syndrome"? Findings in a fetus supporting previous observations.  

PubMed

We report on a fetus with a large deletion of the distal part of the long arm of chromosome 13, (del(13)(q14 --> qter)) congenital anomalies of the urinary system, lungs and extremities, and Dandy-Walker malformation (DWM). Although DWM has been associated with many chromosomal abnormalities and genetic syndromes, its relation to the distal 13q has been demonstrated recently. In 2002, McCormack et al., described two patients with deletions of the long arm of chromosome 13 who had multiple congenital abnormalities along with holoprosencephaly (HPE) and DWM. The phenotypic features and autopsy findings of a fetus with "distal 13q deletion syndrome" at 22 weeks gestation are discussed and comparison with the previous two cases is made. The findings support the previous hypothesis suggesting that haploinsufficiency at a locus within 13q22-33 due to microdeletions may be responsible for isolated DWM in some of the patients. Detailed examination of 13q (13q22-33) by means of conventional and molecular cytogenetic methods is necessary in cases with DWM. PMID:15948192

Alanay, Yasemin; Akta?, Dilek; Utine, Eda; Talim, Beril; Ondero?lu, Lütfü; Ca?lar, Melda; Tunçbilek, Ergül

2005-07-30

273

Partial deletions of the long arm of chromosome 13 associated with holoprosencephaly and the Dandy-Walker malformation.  

PubMed

Two patients with partial deletions of the long arm of chromosome 13, del(13)(13q21-q34) and del(13)(13q22-q33), respectively, multiple congenital anomalies including holoprosencephaly (HPE) and the Dandy-Walker malformation (DWM) are described. The occurrence of HPE and the DWM in both of these patients suggests that, in addition to ZIC2, which is important for normal development of the forebrain, there is at least one other dosage-sensitive gene in 13q22-q33 that plays an important role in brain development. The DWM is anatomically and developmentally distinct from HPE. The presence of a DWM in each of these two patients with partial deletions of the long arm of chromosome 13 suggests that haploinsufficiency at a locus in 13q22-q33 may cause this anomaly. These findings suggest that microdeletions in 13q22-q33 may be found in a proportion of patients with an apparently isolated DWM. Therefore, careful high-resolution cytogenetic analysis (550 band level or greater) of 13q22-q33 may be considered in these patients. Furthermore, future molecular studies of this region may reveal candidate gene loci for the DWM. PMID:12376941

McCormack, W Michael; Shen, Joseph J; Curry, Stacey M; Berend, Sue Ann; Kashork, Catherine; Pinar, Halit; Potocki, Lorraine; Bejjani, Bassem A

2002-11-01

274

Partial deletions of the long arm of chromosome 13 associated with holoprosencephaly and the Dandy-Walker malformation.  

PubMed

Two patients with partial deletions of the long arm of chromosome 13, del(13)(13q21-q34) and del(13)(13q22-q33), respectively, multiple congenital anomalies including holoprosencephaly (HPE) and the Dandy-Walker malformation (DWM) are described. The occurrence of HPE and the DWM in both of these patients suggests that, in addition to ZIC2, which is important for normal development of the forebrain, there is at least one other dosage-sensitive gene in 13q22-q33 that plays an important role in brain development. The DWM is anatomically and developmentally distinct from HPE. The presence of a DWM in each of these two patients with partial deletions of the long arm of chromosome 13 suggests that haploinsufficiency at a locus in 13q22-q33 may cause this anomaly. These findings suggest that microdeletions in 13q22-q33 may be found in a proportion of patients with an apparently isolated DWM. Therefore, careful high-resolution cytogenetic analysis (550 band level or greater) of 13q22-q33 may be considered in these patients. Furthermore, future molecular studies of this region may reveal candidate gene loci for the DWM. PMID:12698964

McCormack, W Michael; Shen, Joseph J; Curry, Stacey M; Berend, Sue Ann; Kashork, Catherine; Pinar, Halit; Potocki, Lorraine; Bejjani, Bassem A

2003-04-15

275

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

NASA Astrophysics Data System (ADS)

What are the temporal and spatial patterns of faulting across shear zones with overlapping parallel faults that are preferentially oriented to accommodate regional shear? How should earthquake hazard be modeled if these systems have variable earthquake recurrence? We explore these questions in the Northern Walker Lane, a 100-km-wide zone of dextral shear along the eastern side of the Sierra Nevada, which accommodates ~15% of the 50 mm/yr of relative motion between the Pacific and North American plates. We used high-resolution airborne Light Distance and Ranging (LiDAR) data to create surficial geologic maps, conducted paleoseismic trenching, applied Quaternary geochronology, and collected high-resolution seismic-reflection profiles along a fault-perpendicular transect across the principal, subparallel, northwest-striking Mohawk Valley, Grizzly Valley, Honey Lake, and Warm Springs Valley dextral-slip faults. Key results along this transect from southwest-to-northeast are: (1) trenching at the Sulphur Creek Sidehill Bench site on the Mohawk Valley fault system indicates four surface-rupturing earthquakes since ~14 ka, which is fewer events than inferred from the slip rate of 2.9 mm/yr from geodetic block-models. To reconcile these results, we suggest that strain is widely distributed on numerous uncharacterized fault strands or that the contemporary (geodetic block model) rate is a young phenomena and hasn't been sustained since 14 ka. (2) High-resolution shallow seismic-reflection imaging and topographic analysis using the LiDAR data provide the first conclusive evidence that the Grizzly Valley fault system is an active Quaternary structure, with probable motion in the latest Quaternary. This result is significant because this fault system is not presently included in the USGS Quaternary fault-and-fold database, is not specified as a seismic source in most regional hazard models, and is also not defined as a boundary in regional geodetic block models. (3) New analysis of faulted, post-Lahontan fluvial terrace risers along the Honey Lake fault system suggests an average slip rate of 2.3 mm/yr since 15.8 ka, but the rate may have slowed to 1.3 mm/yr since the mid Holocene. The latter rate is consistent with geodetic block models. (4) A late Quaternary slip record for the Warm Springs Valley fault system suggests that, the fault had a slip rate of 2.5-3.8 mm/yr from ~50-15 ka, but since 15.8 ka, the rate has been <0.2 mm/yr. We speculate that the slip-rate variability may be linked to co-varying slip with the overlapping and adjacent Honey Lake fault, but additional late Quaternary slip-rate data are needed for the Honey Lake fault to test this hypothesis. In summary, the results along this transect led to identification of new, active Quaternary faults and revealed evidence for spatial and temporal slip-rate variability on parallel and overlapping strike-slip faults in the Northern Walker Lane. We propose that the recognition of new active structures and temporal variations in slip rates may help explain discrepancies between long-term geologic and modern geodetic slip rates across this region. We now need to determine whether a long-term slip rate or the recent record of the last few thousand years is most representative of a fault's near-term earthquake potential.

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

2013-12-01

276

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

NASA Astrophysics Data System (ADS)

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.

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

1997-05-01

277

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

USGS Publications Warehouse

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.

Williams, A. Park; Funk, Chris

2011-01-01

278

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

279

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

PubMed Central

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

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

280

Late quaternary slip-rate variations along the Warm Springs Valley fault system, northern Walker Lane, California-Nevada border  

USGS Publications Warehouse

The extent to which faults exhibit temporally varying slip rates has important consequences for models of fault mechanics and probabilistic seismic hazard. Here, we explore the temporal behavior of the dextral?slip Warm Springs Valley fault system, which is part of a network of closely spaced (10–20 km) faults in the northern Walker Lane (California–Nevada border). We develop a late Quaternary slip record for the fault using Quaternary mapping and high?resolution topographic data from airborne Light Distance and Ranging (LiDAR). The faulted Fort Sage alluvial fan (40.06° N, 119.99° W) is dextrally displaced 98+42/-43 m, and we estimate the age of the alluvial fan to be 41.4+10.0/-4.8 to 55.7±9.2??ka, based on a terrestrial cosmogenic 10Be depth profile and 36Cl analyses on basalt boulders, respectively. The displacement and age constraints for the fan yield a slip rate of 1.8 +0.8/-0.8 mm/yr to 2.4 +1.2/-1.1 mm/yr (2?) along the northern Warm Springs Valley fault system for the past 41.4–55.7 ka. In contrast to this longer?term slip rate, shorelines associated with the Sehoo highstand of Lake Lahontan (~15.8??ka) adjacent to the Fort Sage fan are dextrally faulted at most 3 m, which limits a maximum post?15.8 ka slip rate to 0.2??mm/yr. These relations indicate that the post?Lahontan slip rate on the fault is only about one?tenth the longer?term (41–56 ka) average slip rate. This apparent slip?rate variation may be related to co?dependent interaction with the nearby Honey Lake fault system, which shows evidence of an accelerated period of mid?Holocene earthquakes.

Gold, Ryan; dePolo, Craig; Briggs, Richard; Crone, Anthony

2013-01-01

281

Cyclic diguanosine monophosphate represses bacterial flagella synthesis by interacting with the Walker A motif of the enhancer-binding protein FleQ.  

PubMed

The transcription factor FleQ is a bacterial AAA+ ATPase enhancer-binding protein that is the master activator of flagella gene expression in the opportunistic bacterial pathogen Pseudomonas aeruginosa. Homologs of FleQ are present in all Pseudomonas species and in many polarly flagellated gamma proteobacteria. Cyclic diguanosine monophosphate (c-di-GMP) is a second messenger that controls the transition between planktonic and biofilm modes of growth in bacteria in response to diverse environmental signals. C-di-GMP binds to FleQ to dampen its activity, causing down-regulation of flagella gene expression. This action is potentiated in the simultaneous presence of another protein, FleN. We explored the effect of c-di-GMP and FleN on the ATPase activity of FleQ and found that a relatively low concentration of c-di-GMP competitively inhibited FleQ ATPase activity, suggesting that c-di-GMP competes with ATP for binding to the Walker A motif of FleQ. Confirming this, a FleQ Walker A motif mutant failed to bind c-di-GMP. FleN, whose gene is regulated by FleQ, also inhibited FleQ ATPase activity, and FleQ ATPase activity was much more inhibited by c-di-GMP in the presence of FleN than in its absence. These results indicate that FleN and c-di-GMP cooperate to inhibit FleQ activity and, by extension, flagella synthesis in P. aeruginosa. The Walker A motif of FleQ is perfectly conserved, opening up the possibility that other AAA+ ATPases may respond to c-di-GMP. PMID:24167275

Baraquet, Claudine; Harwood, Caroline S

2013-11-12

282

Cyclic diguanosine monophosphate represses bacterial flagella synthesis by interacting with the Walker A motif of the enhancer-binding protein FleQ  

PubMed Central

The transcription factor FleQ is a bacterial AAA+ ATPase enhancer-binding protein that is the master activator of flagella gene expression in the opportunistic bacterial pathogen Pseudomonas aeruginosa. Homologs of FleQ are present in all Pseudomonas species and in many polarly flagellated gamma proteobacteria. Cyclic diguanosine monophosphate (c-di-GMP) is a second messenger that controls the transition between planktonic and biofilm modes of growth in bacteria in response to diverse environmental signals. C-di-GMP binds to FleQ to dampen its activity, causing down-regulation of flagella gene expression. This action is potentiated in the simultaneous presence of another protein, FleN. We explored the effect of c-di-GMP and FleN on the ATPase activity of FleQ and found that a relatively low concentration of c-di-GMP competitively inhibited FleQ ATPase activity, suggesting that c-di-GMP competes with ATP for binding to the Walker A motif of FleQ. Confirming this, a FleQ Walker A motif mutant failed to bind c-di-GMP. FleN, whose gene is regulated by FleQ, also inhibited FleQ ATPase activity, and FleQ ATPase activity was much more inhibited by c-di-GMP in the presence of FleN than in its absence. These results indicate that FleN and c-di-GMP cooperate to inhibit FleQ activity and, by extension, flagella synthesis in P. aeruginosa. The Walker A motif of FleQ is perfectly conserved, opening up the possibility that other AAA+ ATPases may respond to c-di-GMP.

Baraquet, Claudine; Harwood, Caroline S.

2013-01-01

283

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

NASA Astrophysics Data System (ADS)

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

Umhoefer, P. J.

2012-12-01

284

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

USGS Publications Warehouse

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.

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

1979-01-01

285

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

SciTech Connect

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.

Kim, S.P. (Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States) Department of Physics Education, College of Education, Seoul National University, Seoul 151-742 (Korea, Republic of)); Page, D.N. (Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, T6G 2J1 (Canada))

1992-05-15

286

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

PubMed

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

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

2007-03-19

287

Behavioral responses of male epiphyasPostvittana (walker) to sex pheromone-baited delta trap in a wind tunnel.  

PubMed

The effects of parameters associated with a Delta sticky trap on the sex pheromone-mediated responses of maleEpiphyas postvittana (Walker) were tested in a wind tunnel. Males flying to a pheromone source landed closer to the source when other males were stuck on the base, suggesting the importance of visual cues in the landing behavior of males of this species. With an increase in time (numerical order of the male in the experiment), males became stuck on the base farther from the source whether or not other males were stuck on the base. The alignment of the trap to the wind or the location of the pheromone source within the trap did not significantly affect the percentages of males that entered the trap, but both significantly affected the position at which males entered the trap. When these data were corrected for the probability of catching males, a treatment with the source to the side of the trap was predicted to catch more moths than the other treatments tested, although this difference was not significant. However, in a field-trapping experiment the treatment with the source to the side caught significantly more moths than treatments with the source either in the middle or near the top of the trap. This latter result is probably due to the greater efficiency of the trap when the source is in this position, as indicated in the wind-tunnel experiment, rather than an increase in the numberof males entering the trap. Finally, the pheromone-mediated responses of malePlanotortrix octo were tested to the various trap alignments. As the angle of the trap to the wind increased, significantly fewerP. octo males entered the trap, due principally to both fewer males orienting to the source and proceeding to enter the trap after having landed on it. This difference between the responses ofP. octo andE. postvittana males is, we believe, due to the breakdown in plume structure from the source as the trap angle to the wind increases and to a greater sensitivity ofP. octo males to a more structured pheromone plume. This accounts, at least to some extent, for the consistently greater field catches ofE. postvittana overP. octo (and possibly other New Zealand leafroller moths) in many locations throughout New Zealand. PMID:24257804

Foster, S P; Muggleston, S J; Ball, R D

1991-07-01

288

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)

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.

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

2008-12-01

289

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

290

Development and utilization of a Walker 256 tumor-induced osteogenic small animal model for study of (Tc-99m)diphosphonate complexes  

SciTech Connect

The objective of this research was to develop and utilize a Walker 256 tumor induced osteogenic small animal model to study /sup 99m/Tc(NaBH/sub 4/)HEDP complexes. A solid tumor was induced in muscles adjacent to the tibia of Fischer-344 rats by the implantation of Walker 256 carcinoma cells. Histopathological studies confirmed the induction of discrete osteogenesis on the periosteal surface of the tibia. The biodistribution of (/sup 99m/Tc)HMDP and (/sup 99m/Tc)MDP was determined in 18 tumor bearing animals and in the same number of normal animals. The results of the study were found to be comparable with clinical findings in humans. The model was proved to be valid for studying bone imaging agents. Seven /sup 99m/Tc(NaBH/sub 4/)HEDP complexes were obtained from the separation of a reaction mixture by anion exchange HPLC. Two complexes were treated as a single entity. Six biodistribution studies of /sup 99m/Tc(NaBH/sub 4/)HEDP complexes were conducted. Results indicated that each complex had a distinct biodistribution pattern.

Cheng, K.T.C.

1985-01-01

291

PoreWalker: A Novel Tool for the Identification and Characterization of Channels in Transmembrane Proteins from Their Three-Dimensional Structure  

PubMed Central

Transmembrane channel proteins play pivotal roles in maintaining the homeostasis and responsiveness of cells and the cross-membrane electrochemical gradient by mediating the transport of ions and molecules through biological membranes. Therefore, computational methods which, given a set of 3D coordinates, can automatically identify and describe channels in transmembrane proteins are key tools to provide insights into how they function. Herein we present PoreWalker, a fully automated method, which detects and fully characterises channels in transmembrane proteins from their 3D structures. A stepwise procedure is followed in which the pore centre and pore axis are first identified and optimised using geometric criteria, and then the biggest and longest cavity through the channel is detected. Finally, pore features, including diameter profiles, pore-lining residues, size, shape and regularity of the pore are calculated, providing a quantitative and visual characterization of the channel. To illustrate the use of this tool, the method was applied to several structures of transmembrane channel proteins and was able to identify shape/size/residue features representative of specific channel families. The software is available as a web-based resource at http://www.ebi.ac.uk/thornton-srv/software/PoreWalker/.

Thornton, Janet M.

2009-01-01

292

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

NASA Astrophysics Data System (ADS)

The Mohawk Valley and Honey Lake/Warm Springs faults are parallel, northwest striking, dextral fault systems separated by ~50 km in the westernmost part of the Northern Walker Lane. These two faults work as a cooperative pair to accommodate 3-5 mm/yr of the total 8 mm/yr of right-lateral deformation geodetically observed across the Northern Walker Lane, however it is unclear with fault is dominant. Geologic studies of the faults result in right-lateral slip rates of 1-2.5 mm/yr on the Honey Lake fault and a minimum of 0.3 mm/yr on the Mohawk Valley fault. In contrast, previous geodetic studies estimate slip rates of ~1 mm/yr on the Honey Lake fault and ~3 mm/yr on the Mohawk Valley fault. To reconcile the discrepancy between the distribution of slip on the faults and the differences between sums of the geologically and geodetically estimated slip rates, we use new GPS data to constrain an elastic block model developed specifically to study the Mohawk Valley and Honey Lake/Warm Springs fault systems. We present a dense GPS velocity solution (~10 km average station spacing) that incorporates new data from the semi-continuous Mobile Array of GPS for Nevada Transtension network (MAGNET, http://geodesy.unr.edu/networks) operated by the University of Nevada, Reno with continuous data from the EarthScope Plate Boundary Observatory and other networks. Data collected during the summer of 2012 bring many MAGNET GPS time series in the Northern Walker Lane to near 5 years in duration. The density of our velocity field and recent advances in data processing give us unprecedented precision in the measurement of contemporary deformation in the Northern Walker Lane. We use the velocity solution to solve for slip rates on the companion fault systems and explore the effects of block model geometry assumptions and tradeoffs. Our model predicts slip rates of 2.2±0.3 mm/yr for the Mohawk Valley fault and 1.1±0.2 mm/yr for the Honey Lake fault. Block model slip rate estimates are sensitive to slip rate estimates on neighboring faults. We use a grid-search approach with dextral slip rates on the Mohawk Valley and Honey Lake faults set a priori to test the effect of different slip rate combinations on model misfit. Model misfit is most sensitive to variations in the Mohawk Valley slip rate, with right-lateral slip rates of 1.5-3.5 mm/yr being preferred. Model misfit is less affected by variations in the Honey Lake slip rate, with right-lateral slip rates between 0-3.5 mm/yr resulting in the lowest misfit. Both the misfit test and our slip rate results support the conclusion of previous geodetic studies that the Mohawk Valley fault is currently the dominant fault accommodating right-lateral deformation in the Northern Walker Lane.

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

2012-12-01

293

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

SciTech Connect

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.

Schmid, Christoph [ETH Zurich, Institute for Theoretical Physics, 8093 Zurich (Switzerland)

2009-03-15

294

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

295

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

NASA Astrophysics Data System (ADS)

Since ~30 Ma, western North America has been evolving from an Andean type margin to a dextral transform. Transform growth has been marked by arc retreat, orogenic collapse, and inland steps of the San Andreas fault system (SAF). In the western Great Basin (WGB), a system of dextral faults, known as the Walker Lane (WL) in the north and eastern California shear zone (ECSZ) in the south, currently accommodates ~20% of the Pacific - North America dextral motion. In contrast to the continuous 1100-km-long SAF, discontinuous ~10-250-km-long dextral faults comprise the WL-ECSZ. Displacement across the WL-ECSZ decreases N-ward from ?60 km in south to E-central California, to ~25 km in NW Nevada, to zero in NE California. Geodetic strain rates are ~10 mm/yr across the WL-ECSZ in the WGB but decrease to <2.5 mm/yr at the NW terminus in NE California. The evolution of the WL-ECSZ is closely linked to events along the SAF. The early Miocene elimination of microplates along the southern California coast, S-ward steps in the Rivera triple junction at 19-16 Ma and 13 Ma, and an increase in plate motions ~12 Ma induced the first major episode of deformation in the WL-ECSZ, which began ~13 Ma along the N60°W-trending Las Vegas shear zone (LVSZ). The LVSZ shear zone paralleled plate motions, formed inboard of where the SAF initially organized into a through-going structure, and accommodated ~60 km of right slip ~13 to 6 Ma. In the late Miocene, the southern part of the transform shifted (~13-6 Ma) east to the Gulf of California (GC), the Big Bend of the SAF developed, and plate motions changed from ~N60°W to N37°W (11-6 Ma). Coincidentally (~11-6 Ma), dextral shear shifted west in the WL-ECSZ from the LVSZ to a NNW belt in the WGB. Dextral shear was favored in the WGB as it paralleled the new plate motion, aligned with the GC, and avoided the Big Bend bottleneck. By ~4 Ma, dextral shear had propagated to the northern WL (NW Nevada - NE California) in concert with the N-ward migration of the Mendocino triple junction (MTJ). The northern WL is the least developed part of the WL-ECSZ, with right slip decreasing from ~25 km to zero to the NW. Here, en echelon left-stepping dextral faults are analogous to Riedel shears developed above a through-going shear zone at depth. Coeval extension and dextral shear have induced slight counterclockwise rotations, which may ultimately rotate Riedel shears toward the main shear zone at depth, facilitate hard linkage between Riedel shears, and produce a through-going strike-slip fault. The WL-ECSZ now terminates near the south end of the Cascade arc near the latitude of the MTJ, suggesting that the SAF and WL-ECSZ are migrating N-ward at similar rates. With continued N-ward migration, the MTJ will collide with the NW-propagating WL off southern Oregon in ~8 Ma. The plate boundary will then likely jump inland to the WL-ECSZ. The current setting is one stage in the progressive dismembering of an Andean type margin through lateral growth and inland stepping of a transform fault. This process is fragmenting the continental margin and transferring slices of North America to the Pacific plate. Evolving transform faults may therefore be important in generating far-traveled exotic terranes.

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

2009-12-01

296

Temporal variations in extension rate on the Lone Mountain fault and strain distribution in the eastern California shear zone-Walker Lane  

NASA Astrophysics Data System (ADS)

The eastern California shear zone (ECSZ) and Walker Lane represent an evolving segment of the Pacific-North America plate boundary. Understanding temporal variations in strain accumulation and release along plate boundary structures is critical to assessing how deformation is accommodated throughout the lithosphere. Late Pleistocene displacement along the Lone Mountain fault suggests the Silver Peak-Lone Mountain (SPLM) extensional complex is an important structure in accommodating and transferring strain within the ECSZ and Walker Lane. Using geologic and geomorphic mapping, differential global positioning system surveys, and terrestrial cosmogenic nuclide (TCN) geochronology, we determined rates of extension across the Lone Mountain fault in western Nevada. The Lone Mountain fault displaces the northwestern Lone Mountain and Weepah Hills piedmonts and is the northeastern component of the SPLM extensional complex, a series of down-to-the-northwest normal faults. We mapped seven distinct alluvial fan deposits and dated three of the surfaces using 10Be TCN geochronology, yielding ages of 16.5 ± 1.2 ka, 92 ± 9 ka, and 137 ± 25 ka for the Q3b, Q2c, and Q2b deposits, respectively. The ages were combined with scarp profile measurements across the displaced fans to obtain minimum rates of extension; the Q2b and Q2c surfaces yield an extension rate between 0.1 ± 0.1 and 0.2 ± 01 mm/yr and the Q3b surface yields a rate of 0.2 ± 0.1 to 0.4 ± 0.1 mm/yr, depending on the dip of the fault. Active extension on the Lone Mountain fault suggests that it helps partition strain off of the major strike-slip faults in the northern ECSZ and transfers deformation to the east around the Mina Deflection and northward into the Walker Lane. Combining our results with estimates from other faults accommodating dextral shear in the northern ECSZ reveals an apparent discrepancy between short- and long-term rates of strain accumulation and release. If strain rates have remained constant since the late Pleistocene, this could reflect transient strain accumulation, similar to the Mojave segment of the ECSZ. However, our data also suggest a potential increase in strain rates between ~92 ka and ~17 ka, and possibly to present day, which may also help explain the mismatch between long- and short-term rates of deformation in the region.

Hoeft, J. S.; Frankel, K. L.

2010-12-01

297

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

298

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

PubMed Central

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.

2013-01-01

299

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)

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.

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

2011-10-01

300

Style of deformation along the Death Valley-Furnace Creek fault zone and other faults in the southern Walker Lane, Nevada and California  

SciTech Connect

Quaternary normal and right-lateral faults and associated lineaments in the southern part of the Walker Lane are anomalous with respect to the north-striking normal faults in most of the central Great Basin. The authors identify and characterize many faults and lineaments that were previously unmapped, with the exception of faults in the Death Valley-Furnace Creek fault zone (DVFCFZ) and some faults in and near the Nevada Test Site. Faults and associated lineaments in deposits of late Cenozoic age are distinguished on the basis of age of most recent activity and orientation, and are grouped into two domains. One domain is characterized by northwest-striking faults and lineaments and associated north-striking en echelon structures within the DVFCFZ and the Pahrump fault zone; the other domain is characterized by north- to northeast-striking faults and linearments within a broad region east of the DVFCFZ that narrows southward toward the Pahrump fault zone. Preliminary observations of faults and linearments suggest dominantly right-oblique slip in the first domain and dominantly dip-slip in the second domain. The DVFCFZ is a regional right-lateral strike-slip system that shows changes in style of deformation along strike. Numerous normal faults at the northern end of the DVFCFZ in northern fish Lake Valley and the Volcanic Hills form an extensional right step that links the DVFCFZ with northwest-striking right-lateral faults of the northern part of the Walker Lane. South of this extensional step, the DVFCFZ trends southeast along strike-slip faults from central Fish Lake Valley to the latitude of Furnace Creek. From Furnace Creek, the fault zone apparently steps left to the Pahrump fault zone in the area of Ash Meadows where a complex zone of folds and faults of diverse orientation suggest local compression. This stepover coincides with east-northeast-striking faults that appear to be an extension of the left-lateral Rock Valley fault zone.

Noller, J.S. (William Lettis and Associates, Inc., Oakland, CA (United States)); Reheis, M.C. (Geological Survey, Denver, CO (United States))

1993-04-01

301

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

302

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)

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.

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

2012-12-01

303

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

SciTech Connect

In 2009, the Gulf of Mexico (GOM) Gas Hydrates Joint-Industry-Project (JIP) Leg II drilling program confirmed that gas hydrate occurs at high saturations within reservoir-quality sands in the GOM. A comprehensive logging-while-drilling dataset was collected from seven wells at three sites, including two wells at the Walker Ridge 313 site. By constraining the saturations and thicknesses of hydrate-bearing sands using logging-while-drilling data, two-dimensional (2D), cylindrical, r-z and three-dimensional (3D) reservoir models were simulated. The gas hydrate occurrences inferred from seismic analysis are used to delineate the areal extent of the 3D reservoir models. Numerical simulations of gas production from the Walker Ridge reservoirs were conducted using the depressurization method at a constant bottomhole pressure. Results of these simulations indicate that these hydrate deposits are readily produced, owing to high intrinsic reservoir-quality and their proximity to the base of hydrate stability. The elevated in situ reservoir temperatures contribute to high (5–40 MMscf/day) predicted production rates. The production rates obtained from the 2D and 3D models are in close agreement. To evaluate the effect of spatial dimensions, the 2D reservoir domains were simulated at two outer radii. The results showed increased potential for formation of secondary hydrate and appearance of lag time for production rates as reservoir size increases. Similar phenomena were observed in the 3D reservoir models. The results also suggest that interbedded gas hydrate accumulations might be preferable targets for gas production in comparison with massive deposits. Hydrate in such accumulations can be readily dissociated due to heat supply from surrounding hydrate-free zones. Special cases were considered to evaluate the effect of overburden and underburden permeability on production. The obtained data show that production can be significantly degraded in comparison with a case using impermeable boundaries. The main reason for the reduced productivity is water influx from the surrounding strata; a secondary cause is gas escape into the overburden. The results dictate that in order to reliably estimate production potential, permeability of the surroundings has to be included in a model.

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

2012-06-01

304

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

PubMed Central

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.

Siddique, Azeem; Figurski, David H.

2012-01-01

305

The importance of in-stream uptake for regulating stream concentrations and outputs of N and P from a forested watershed: evidence from long-term chemistry records for Walker Branch Watershed  

Microsoft Academic Search

Long-term, weekly measurements of streamwater nitrogen and phosphorus concentrations in the West Fork of Walker Branch, a 1st order forested stream in eastern Tennessee, were used to assess the importance of in-stream processes for controlling stream concentrations and watershed exports. Over the period from 1991 to 2002, there was a slight declining trend in watershed export of dissolved inorganic N

Patrick J. Mulholland

2004-01-01

306

Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes  

PubMed Central

Background Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. Methods In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells. Results WF decreased the viability of C2C12 myotubes, especially at concentrations of 20–25 ?g.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. Conclusion These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model.

Yano, Claudia L; Ventrucci, Gislaine; Field, William N; Tisdale, Michael J; Gomes-Marcondes, Maria Cristina C

2008-01-01

307

Full implementation of the secondary 1 program of project P.A.T.H.S.: observations based on the co-walker scheme.  

PubMed

This study was conducted in order to understand the implementation quality of the Secondary 1 Program of the Tier 1 Program of the Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes) in the first year of the Full Implementation Phase. Classroom observations of 137 units in 85 schools were conducted under the Co-Walker Scheme. Results showed that the overall level of program adherence was generally high, with an average of 86.57%. Thirteen aspects concerning program delivery were significantly correlated. Multiple regression analyses revealed that (1) overall implementation quality was significantly predicted by interactive delivery method, use of positive and supportive feedback, opportunity for reflection, degree of achievement of the objectives, and lesson preparation; whereas (2) success of implementation was significantly predicted by student interest, interactive delivery method, use of positive and supportive feedback, opportunity for reflection, and degree of achievement of the objectives. In general, the present study suggests that the implementation quality of the Project P.A.T.H.S. is good. PMID:19802492

Shek, Daniel T L; Sun, Rachel C F; Kan, Vivian W M

2009-01-01

308

Successful treatment of Dandy-Walker syndrome by endoscopic third ventriculostomy in a 6-month-old girl with progressive hydrocephalus: a case report and literature review.  

PubMed

Dandy-Walker syndrome (DWS) is a congenital brain malformation involving the cerebellum and fourth ventricle. We report a 6-month-old girl with DWS presenting an initially normal ventricular system and mild cyst-like lesion over the posterior fossa as assessed by postnatal brain sonography. However, symptoms and signs of increased intracranial cerebral pressure in terms of frequent vomiting and tense anterior fontanel developed, and these were associated with mild hypotonia and poor neck support, and upward-gaze palsy at the age of 6 months. Magnetic resonance imaging revealed a huge cystic lesion of the fourth ventricle, which filled the posterior fossa and ventricular dilatation. The tentorium was progressively displaced upward by the cyst. A nearly complete agenesis of the cerebellar vermis was also confirmed. After a successful endoscopic third ventriculostomy, a series of brain magnetic resonance imaging scans, taken during a follow-up survey, showed normal lateral and third ventricles. Consequently, symptoms of intracranial cerebral pressure resolved, and a developmental milestone was achieved. In conclusion, DWS can be confirmed postpartum, and endoscopic third ventriculostomy was found to be a preferential operative procedure for DWS with hydrocephalus. It may be effective for patients younger than 1 year. PMID:21385657

Hu, Chih-Fen; Fan, Hueng-Chuen; Chang, Cheng-Fu; Wang, Chih-Chien; Chen, Shyi-Jou

2011-02-01

309

Heterorhabditis sonorensis n. sp. (Nematoda: Heterorhabditidae), a natural pathogen of the seasonal cicada Diceroprocta ornea (Walker) (Homoptera: Cicadidae) in the Sonoran desert.  

PubMed

A new Heterorhabditis species was isolated from nymphal stages of the seasonal cicada Diceroprocta ornea (Walker) in an asparagus field in the state of Sonora, Mexico. Concomitantly, another isolate of the same nematode species was also collected from an oak woodland habitat in the Chiricahua mountain range in southeastern Arizona. Morphological and molecular studies together with cross-hybridization tests indicate these two isolates are conspecific and represent a new undescribed Heterorhabditis sp. This new species is distinguished from other species in this genus by a combination of several qualitative and quantitative morphological traits. Key diagnostic features include: presence of a pronounced post-anal swelling in the hermaphrodite; male with nine pairs of bursal rays, with pairs 4 and 7 bent outwards and one pair of papillae placed on the cloacal opening, value of D% (average: 79); infective juveniles with a well developed cuticular tooth, long tail (average: 105mum) and values of D% (average: 90) and E% (average: 99). In addition to these diagnostic characters, cross-hybridization tests between the new species with H. bacteriophora and H. mexicana yielded no fertile progeny. Comparison of ITS rDNA sequences with other available sequences of described species depicted the two isolates as a new species. Phylogenetic analysis of these sequence data placed H. sonorensis n. sp. as a member of the indica-group. PMID:19114047

Stock, S Patricia; Rivera-Orduño, Benjamin; Flores-Lara, Yolanda

2009-03-01

310

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

PubMed

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

Tomasin, Rebeka; Gomes-Marcondes, Maria Cristina Cintra

2011-04-01

311

Conserved Asp327 of Walker B motif in the N-terminal Nucleotide Binding Domain (NBD-1) of Cdr1p of Candida albicans has acquired a new role in ATP hydrolysis  

PubMed Central

The Walker A and B motifs of nucleotide binding domains (NBDs) of Cdr1p though almost identical to all ABC transporters, has unique substitutions. We have in the past shown that Trp326 of Walker B and Cys193 of Walker A motifs of N-terminal NBD of Cdr1p have distinct roles in ATP binding and hydrolysis, respectively. In the present study, we have examined the role of a well conserved Asp327 in the Walker B motif of the N-terminal NBD which is preceded (Trp326) and followed (Asn328) by atypical amino acid substitutions and compared it with its equivalent well conserved Asp1026 of the C-terminal NBD of Cdr1p. We observed that the removal of the negative charge by D327N, D327A, D1026N, D1026A and D327N/D1026N substitutions, resulted in Cdr1p mutant variants that were severely impaired in ATPase activity and drug efflux. Importantly, all the mutant variants showed characteristics similar to those of wild type with respect to cell surface expression and photoaffinity drug analogue [125I] IAAP and [3H] azidopine labeling. While Cdr1p D327N mutant variant showed comparable binding with [?-32P] 8-azido ATP, Cdr1p D1026N and Cdr1p D327N/D1026N mutant variants were crippled in nucleotide binding. That the two conserved carboxylate residues Asp327 and Asp1026 are functionally different was further evident from the pH profile of ATPase activity. Cdr1p D327N mutant variant showed ?40% enhancement of its residual ATPase activity at acidic pH while no such pH effect was seen with Cdr1p D1026N mutant variant. Our experimental data suggest that Asp327 of N-terminal NBD has acquired a new role to act as a catalytic base in ATP hydrolysis, a role normally conserved for Glu present adjacent to the conserved Asp in the Walker B motif of all the non-fungal transporters.

Rai, Versha; Gaur, Manisha; Shukla, Sudhanshu; Shukla, Suneet; Ambudkar, Suresh V.; Komath, Sneha Sudha; Prasad, Rajendra

2008-01-01

312

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

PubMed

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

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

2007-12-01

313

Suppressed post-15.8 ka slip rate along the Warm Springs Valley fault, northern Walker Lane, California-Nevada border  

NASA Astrophysics Data System (ADS)

Establishing the temporal variability of fault slip rates contributes to improved seismic-hazard mitigation, modeling of fault mechanics, and understanding continental dynamics. We explore the late Quaternary temporal behavior of the dextral-slip Warm Springs Valley fault system, which is part of a network of closely spaced (10 to 20 km) faults in the northern Walker Lane (California-Nevada border). We develop a slip record for the fault system using Quaternary mapping and high-resolution (15-17 points/m 2) topographic data from Airborne Laser Swath Mapping (ALSM). The fault dextrally displaces the Fort Sage alluvial fan (40.06°N, 119.99°W) 85.8 +8.6/-10.4 m, and we model the age of this alluvial fan to be 44.0 +8.6/-8.9 ka based on a terrestrial cosmogenic exposure 10Be depth profile. The fan's displacement and age constraints yield an average late Quaternary slip rate of 2.0 +0.5/-0.6 mm/yr (2?) along the northern Warm Springs Valley fault system. Shorelines, associated with the Sehoo highstand of Lake Lahontan (~15.8 ka) at the toe of the Fort Sage fan, are dextrally faulted at most 2-3 m, which limits a post-15.8 ka slip rate to ?0.2 mm/yr. These relations indicate that the post-Lahontan slip rate on the Warm Springs Valley fault system is only about one-tenth the longer-term (44 ka) average slip rate. This apparent slip-rate variation may be related to interaction with the nearby Honey Lake fault system, which shows evidence of a period of more frequent earthquakes in the mid Holocene.

Gold, R. D.; DePolo, C. M.; Briggs, R. W.; Crone, A. J.

2011-12-01

314

Multiple developmental programs are altered by loss of Zic1 and Zic4 to cause Dandy-Walker malformation cerebellar pathogenesis  

PubMed Central

Heterozygous deletions encompassing the ZIC1;ZIC4 locus have been identified in a subset of individuals with the common cerebellar birth defect Dandy-Walker malformation (DWM). Deletion of Zic1 and Zic4 in mice produces both cerebellar size and foliation defects similar to human DWM, confirming a requirement for these genes in cerebellar development and providing a model to delineate the developmental basis of this clinically important congenital malformation. Here, we show that reduced cerebellar size in Zic1 and Zic4 mutants results from decreased postnatal granule cell progenitor proliferation. Through genetic and molecular analyses, we show that Zic1 and Zic4 have Shh-dependent function promoting proliferation of granule cell progenitors. Expression of the Shh-downstream genes Ptch1, Gli1 and Mycn was downregulated in Zic1/4 mutants, although Shh production and Purkinje cell gene expression were normal. Reduction of Shh dose on the Zic1+/?;Zic4+/? background also resulted in cerebellar size reductions and gene expression changes comparable with those observed in Zic1?/?;Zic4?/? mice. Zic1 and Zic4 are additionally required to pattern anterior vermis foliation. Zic mutant folial patterning abnormalities correlated with disrupted cerebellar anlage gene expression and Purkinje cell topography during late embryonic stages; however, this phenotype was Shh independent. In Zic1+/?;Zic4+/?;Shh+/?, we observed normal cerebellar anlage patterning and foliation. Furthermore, cerebellar patterning was normal in both Gli2-cko and Smo-cko mutant mice, where all Shh function was removed from the developing cerebellum. Thus, our data demonstrate that Zic1 and Zic4 have both Shh-dependent and -independent roles during cerebellar development and that multiple developmental disruptions underlie Zic1/4-related DWM.

Blank, Marissa C.; Grinberg, Inessa; Aryee, Emmanuel; Laliberte, Christine; Chizhikov, Victor V.; Henkelman, R. Mark; Millen, Kathleen J.

2011-01-01

315

AP1S2 is mutated in X-linked Dandy-Walker malformation with intellectual disability, basal ganglia disease and seizures (Pettigrew syndrome).  

PubMed

MRXS5 or Pettigrew syndrome was described 20 years ago in a four generation family including nine affected individuals presenting with facial dysmorphism, intellectual disability, Dandy-Walker malformation and inconstant choreoathetosis. Four individuals had iron deposition in the basal ganglia seen on MRI or at autopsy. The mutation causing Pettigrew has remained elusive since the initial description of the condition. We report the identification of a mutation in the X-linked AP1S2 gene in the original Pettigrew syndrome family using X-chromosome exome sequencing. We report additional phenotype details for several of the affected individuals, allowing us to further refine the phenotype corresponding to this X-linked intellectual disability syndrome. The AP1S2 c.426+1?G>T mutation segregates with the disease in the Pettigrew syndrome family and results in loss of 46 amino acids in the clathrin adaptor complex small chain domain that spans most of the AP1S2 protein sequence. The mutation reported here in AP1S2 is the first mutation that is not predicted to cause a premature termination of the coding sequence or absence of the AP1S2 protein. Although most of the families affected by a mutation in AP1S2 were initially described as having different disorders assigned to at least three different OMIM numbers (MIM 300629, 300630 and 304340), our analysis of the phenotype shows that they are all the same syndrome with recognition complicated by highly variable expressivity that is seen within as well as between families and is probably not explained by differences in mutation severity. PMID:23756445

Cacciagli, Pierre; Desvignes, Jean-Pierre; Girard, Nadine; Delepine, Marc; Zelenika, Diana; Lathrop, Mark; Lévy, Nicolas; Ledbetter, David H; Dobyns, William B; Villard, Laurent

2014-03-01

316

Walker 256 tumour cells increase substance P immunoreactivity locally and modify the properties of the blood-brain barrier during extravasation and brain invasion.  

PubMed

It is not yet known how tumour cells traverse the blood-brain barrier (BBB) to form brain metastases. Substance P (SP) release is a key component of neurogenic inflammation which has been recently shown to increase the permeability of the BBB following CNS insults, making it a possible candidate as a mediator of tumour cell extravasation into the brain. This study investigated the properties of the BBB in the early stages of tumour cell invasion into the brain, and the possible involvement of SP. Male Wistar rats were injected with Walker 256 breast carcinoma cells via the internal carotid artery and euthanised at 1, 3, 6 and 9 days post tumour inoculation. Culture medium-injected animals served as controls at 1 and 9 days. Evidence of tumour cell extravasation across the BBB was first observed at 3 days post-inoculation, which corresponded with significantly increased albumin (p < 0.05) and SP immunoreactivity (p < 0.01) and significantly reduced endothelial barrier antigen labelling of microvessels when compared to culture medium control animals (p < 0.001). By day 9 after tumour cell inoculation, 100 % of animals developed large intracranial neoplasms that had significantly increased albumin in the peri-tumoral area (p < 0.001). The increased SP immunoreactivity and altered BBB properties at 3 days post-inoculation that coincided with early tumour invasion may be indicative of a mechanism for tumour cell extravasation into the brain. Thus, extravasation of tumour cells into the brain to form cerebral metastases may be a SP-mediated process. PMID:22610781

Lewis, Kate M; Harford-Wright, Elizabeth; Vink, Robert; Nimmo, Alan J; Ghabriel, Mounir N

2013-01-01

317

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

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.

2013-01-01

318

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

PubMed

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

Tan, Uner

2007-01-01

319

Competitive Brownian and Lévy walkers.  

PubMed

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. PMID:22680418

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

2012-04-01

320

Collective motion of oscillatory walkers  

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

321

Competitive Brownian and Lévy walkers  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

322

Disease Precautions for Dog Walkers  

MedlinePLUS

... wind to unintended targets (such as other non-aggressive dogs or yourself), and use caution. The best ... dogs or dogs that you know have shown aggression toward people or other dogs. Make sure that ...

323

Walker-256 tumor growth is inhibited by the independent or associative chronic ingestion of shark liver and fish oil: a response linked by the increment of peritoneal macrophages nitrite production in Wistar rats.  

PubMed

Fish oil (FO) is widely known by its capacity to positively modulate immune parameters and decrease the growth of some tumors. Despite the enormous number of studies addressing the effects of FO, there are few reports showing similar results using other marine sources of lipid compounds with biologic importance. This study aimed to compare the effects of shark liver oil (SLO), which is a source of omega-3 fatty acids and alkylglycerols, with those obtained with FO administration, or the association of both, on tumor growth and the innate immune system in Walker-256 tumor-bearing rats. Beginning at 21 days of age, Wistar rats were fed regular chow and/or FO and/or SLO supplement (1 g/kg body weight per day) for 14 weeks. Walker-256 tumor cells were inoculated on the 90th day. As expected, 14 days after inoculation, rats fed with FO presented tumor weights that were 50% lower than the control tumors (P < .05). The association of both FO and SLO and ingestion of SLO alone also reached the same reduction level. Except for adhesion, all macrophage parameters assayed were 200% higher in rats fed with FO and those supplemented with both FO and SLO compared with control rats. Only reactive nitrogen species production was increased by SLO. These results suggest that SLO might also have indirect antitumor properties. Conversely, there were no additive effects when SLO was administered with FO. Therefore, SLO is another marine compound with in vivo antitumor effects, but its action mechanisms seem not to be related to major modifications on macrophage function. PMID:21130296

Belo, Sérgio R B; Iagher, Fabíola; Bonatto, Sandro J; Naliwaiko, Katya; Calder, Philip C; Nunes, Everson A; Fernandes, Luiz C

2010-11-01

324

Contiguous gene syndrome due to a maternally inherited 8.41 Mb distal deletion of chromosome band Xp22.3 in a boy with short stature, ichthyosis, epilepsy, mental retardation, cerebral cortical heterotopias and Dandy-Walker malformation.  

PubMed

Microdeletions of Xp22.3 are associated with contiguous gene syndromes, the extent and nature of which depend on the genes encompassed by the deletion. Common symptoms include ichthyosis, mental retardation and hypogonadism. We report on a boy with short stature, ichthyosis, severe mental retardation, cortical heterotopias and Dandy-Walker malformation. The latter two abnormalities have so far not been reported in terminal Xp deletions. MLPA showed deletion of SHOX and subsequent analysis using FISH and SNP-arrays revealed that the patient had an 8.41 Mb distal deletion of chromosome region Xp22.31 --> Xpter. This interval contains several genes whose deletion can partly explain our patient's phenotype. His cortical heterotopias and DWM suggest that a gene involved in brain development may be in the deleted interval, but we found no immediately obvious candidates. Interestingly, further analysis of the family revealed that the patient had inherited his deletion from his mother, who has a mos 46,X,del(X)(p22)/45,X/46, XX karyotype. PMID:18925676

van Steensel, M A M; Vreeburg, M; Engelen, J; Ghesquiere, S; Stegmann, A P A; Herbergs, J; van Lent, J; Smeets, B; Vles, J H

2008-11-15

325

Replacement of the positively charged Walker A lysine residue with a hydrophobic leucine residue and conformational alterations caused by this mutation in MRP1 impair ATP binding and hydrolysis  

PubMed Central

MRP1 (multidrug resistance protein 1) couples ATP binding/hydrolysis at its two non-equivalent NBDs (nucleotide-binding domains) with solute transport. Some of the NBD1 mutants, such as W653C, decreased affinity for ATP at the mutated site, but increased the rate of ATP-dependent solute transport. In contrast, other NBD1 mutants, such as K684L, had decreased ATP binding and rate of solute transport. We now report that mutations of the Walker A lysine residue, K684L and K1333L, significantly alter the tertiary structure of the protein. Due to elimination of the positively charged group and conformational alterations, the K684L mutation greatly decreases the affinity for ATP at the mutated NBD1 and affects ATP binding at the unmutated NBD2. Although K684L-mutated NBD1 can bind ATP at higher concentrations, the bound nucleotide at that site is not efficiently hydrolysed. All these alterations result in decreased ATP-dependent solute transport to approx. 40% of the wild-type. In contrast, the K1333L mutation affects ATP binding and hydrolysis at the mutated NBD2 only, leading to decreased ATP-dependent solute transport to approx. 11% of the wild-type. Consistent with their relative transport activities, the amount of vincristine accumulated in cells is in the order of K1333L?CFTR (cystic fibrosis transmembrane conductance regulator)>K684L?wild-type MRP1. Although these mutants retain partial solute transport activities, the cells expressing them are not multidrug-resistant owing to inefficient export of the anticancer drugs by these mutants. This indicates that even partial inhibition of transport activity of MRP1 can reverse the multidrug resistance caused by this drug transporter.

Buyse, Frederic; Hou, Yue-xian; Vigano, Catherine; Zhao, Qing; Ruysschaert, Jean-Marie; Chang, Xiu-bao

2006-01-01

326

Activated Random Walkers: Facts, Conjectures and Challenges  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

327

How to Use Crutches, Canes and Walkers  

MedlinePLUS

... foot, you may have to use crutches. Proper Positioning The top of your crutches should reach between ... also help you to keep living independently. Proper Positioning The top of your cane should reach to ...

328

[Chemical constituents of Eupolyphaga sinensis Walker].  

PubMed

Five compounds were isolated from the n-hexane extract and n-butanol of extract Eupolyphaga sinensis. These compounds were identified as octacosanol, beta-sitosterol, batyl alcohol, 2,4-pyrimidinedione and allantoin. PMID:1482536

Lu, Y; Jiang, P

1992-08-01

329

Familial Dandy-Walker malformation and leukodystrophy  

Microsoft Academic Search

We report the first familial cases with two different types of posterior fossa cystic malformation and a leukodystrophic-like aspect on cerebral magnetic resonance imaging (MRI). The girl and her brother had severe encephalopathy, marked hypotonia, absent deep tendon reflexes, macrocrania, gigantism, and dysmorphic face and extremities. The girl had generalized seizures. The boy had unilateral cataract and bilateral optic atrophy.

Véronique T. Humbertclaude; Philippe A. Coubes; Nicolas Leboucq; Bernard B. Echenne

1997-01-01

330

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)

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.

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

2008-12-01

331

Protecting Endangered Species: Interim Measures. Walker County, Georgia.  

National Technical Information Service (NTIS)

The information in the pamphlet is similar to what the U.S. Environmental Protection Agency (EPA) expects to distribute once the Endangered Species Protection Program is in effect. The limitations on pesticide use are not law at this time, but are being p...

1990-01-01

332

Neotectonics, Geodesy and Seismic Hazard in the Northern Walker Lane  

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

333

Effective trapping of random walkers in complex networks  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

334

WALKER'S M'LISSA VERSUS DICKENS'MRS. GAMP  

Microsoft Academic Search

Rites and rituals have always been a part of a cult ure, ever since history. One main reason for this can be explained by the fact t hat people have always feared the unknown. Why are we on earth? Is there a life after death? How can we explain conception and birth? These questions ha ve been asked for centuries

Gönül Bakay

335

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

Federal Register 2010, 2011, 2012, 2013

...Office of Compliance and Field Operations, Directorate for Engineering Sciences, Consumer Product Safety Commission, 4330 East West...including Consumers Union, Consumer Federation of America, and Kids in Danger. These comments and the Commission's...

2010-06-21

336

A hexapod walker using a heterarchical architecture for action selection  

PubMed Central

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.

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

2013-01-01

337

A hexapod walker using a heterarchical architecture for action selection.  

PubMed

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

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

2013-01-01

338

Effective trapping of random walkers in complex networks.  

PubMed

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. PMID:22680541

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

2012-04-01

339

Gauge-invariant perfect-fluid Robertson-Walker perturbations  

NASA Astrophysics Data System (ADS)

In the preceding paper, a complete set of basic gauge-invariant variables was defined that uniquely characterizes cosmological perturbations in homogeneous, isotropic, ideal-fluid universe models. The calculations were presented in some detail for the case of a general perfect fluid with two essential thermodynamic variables. Among other things, it was demonstrated that the aforementioned set consists of 17 linearly independent, not identically vanishing gauge-invariant variables. One can think of these basic variables as having two aspects. First, their definitions are such that they provide a unique representation of the physical perturbation. (By way of digression, inspection shows that such perturbations can be regarded as being the elements of a certain quotient space.) Second, any complicated gauge-invariant quantity is obtainable directly from the basic variables through purely algebraic and differential operations. The object here is the systematic derivation of the linear propagation equations governing the evolution of these basic variables. To make clear the relation of the present formalism to a series of standard results in the literature, this paper also points out how general propagation equations can be adapted to situations where the pressure vanishes in the background. Finally, the physical interpretation of basic variables and comparison with other gauge-invariant approaches are briefly presented.

Banach, Zbigniew; Piekarski, Stawomir

1996-03-01

340

On control and planning of a space station robot walker  

Microsoft Academic Search

A walking robot which can step from one node of a space station trusswork to the next is described. The five DOF robot consists of two light-weight flexible links, configured like an upside-down V, with a rotary joint at the vertex and a gripper connected by two DOF joints at each free end. The development of the control software is

Hiroshi Ueno; Yangsheng Xu; M. Ueno; T. Kanage

1990-01-01

341

A Space Station robot walker and its shared control software  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

342

Eulerian Walkers as a Model of Self-Organized Criticality  

Microsoft Academic Search

We propose a new model of self-organized criticality. A particle is dropped at random on a lattice and moves along directions specified by arrows at each site. As it moves, it changes the direction of the arrows according to fixed rules. On closed graphs these walks generate Euler circuits. On open graphs, the particle eventually leaves the system, and a

V. B. Priezzhev; Deepak Dhar; Abhishek Dhar; Supriya Krishnamurthy

1996-01-01

343

GeoFrame Walker Lane: Overview, Rationale, and Objectives  

Microsoft Academic Search

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

D. F. Stockli

2006-01-01

344

National Uranium Resource Evaluation: Walker Lake Quadrangle, California and Nevada  

SciTech Connect

The Miocene Relief Peak Formation occurs in the Sierra Nevada, where it consists mainly of andesitic flows, autobrecciated flows, and mudflows. However, fluviatile rocks are common in the lower part of the formation. They contain abundant carbonaceous material, are commonly permeable, and are interbedded with less permeable rocks. The Juniper mine, the principal uranium occurrence in the fluviatile rocks, reportedly has produced more than 20 tons of U/sub 3/O/sub 8/. Although rocks of the Relief Peak Formation lack aerial radiometric uranium anomalies and generally have only average uranium content away from uranium occurrences, the fluviatile rocks of the formation are considered favorable for uranium deposits because of their lithologic characteristics and uranium occurrences. Some areas of Tertiary sedimentary rocks presently are categorized as unfavorable for the required minimum endowment. They have some geologically favorable characteristics, however, as well as indications of industry exploration activities, and they may prove to be favorable as more information becomes available.

Durham, D.L.; Felmlee, J.K.

1982-09-01

345

Random Walker Ranking for NCAA Division IA Football  

Microsoft Academic Search

Each December, college football fans and pundits across America debate which\\u000atwo teams should meet in the NCAA Division I-A National Championship game. The\\u000aBowl Championship Series (BCS) standings employed to select the teams invited\\u000ato this game are intended to provide an unequivocal #1 v. #2 game for the\\u000achampionship; however, this selection process has itself been highly\\u000acontroversial

Thomas Callaghan; Peter J. Mucha; Mason A. Porter

2003-01-01

346

Random Walker Ranking for NCAA Division IA Football  

Microsoft Academic Search

Each December, college football fans and pundits across America debate which two teams should meet in the NCAA Division I-A National Championship game. The Bowl Championship Series (BCS) standings employed to select the teams invited to this game are intended to provide an unequivocal #1 v. #2 game for the championship; however, this selection process has itself been highly controversial

Thomas Callaghan; Peter J. Mucha; Mason A. Porter

2003-01-01

347

Bringing the compass-gait bipedal walker to three dimensions  

Microsoft Academic Search

The planar compass-gait biped has been exten- sively studied in the dynamic walking community, motivated by the gravity-based pendular efficiencies of human walking. These results can be extended to three dimensions using controlled geometric reduction for open-chain robots, by which stable 3- D walking gaits are built from known sagittal-plane limit cycles. We apply this method to the standard and

Robert D. Gregg; Mark W. Spong

2009-01-01

348

Self-interacting quantized fields and particle creation in Robertson--Walker universes  

Microsoft Academic Search

The effects of self-interaction on quantum particle creation in cosmological models is investigated. The particular models which are considered are that of a scalar field with an interaction of the form L\\/sub I\\/=-lambdaphi⁴ and that of an electromagnetic field with an interaction of the form L\\/sub I\\/=bâ(F\\/sub munu\\/F\\/sup munu\\/)² +bâ(*F\\/sub munu\\/F\\/sup munu\\/)². In lowest order in the coupling constants, these

N. D. Birrell; L. H. Ford

1979-01-01

349

Characterization of phenoloxidase activity in venom from the ectoparasitoid Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae).  

PubMed

Crude venom isolated from the ectoparasitic wasp Nasonia vitripennis was found to possess phenoloxidase (PO) activity. Enzyme activity was detected by using a modified dot blot analysis approach in which venom samples were applied to nylon membranes and incubated with either L-DOPA or dopamine. Dot formation was most intense with dopamine as the substrate and no activators appeared to be necessary to evoke a melanization reaction. No melanization occurred when venom was incubated in Schneider's insect medium containing 10% fetal bovine serum or when using tyrosine as a substrate, but melanization did occur when larval or pupal plasma from the fly host, Sarcophaga bullata, was exposed to tyrosine. Only fly larval plasma induced an enzyme reaction with the Schneider's insect medium. The PO inhibitor phenylthiourea (PTU) and serine protease inhibitor phenylmethylsulfonylfluoride (PMSF) abolished PO activity in venom and host plasma samples, but glutathione (reduced) only inhibited venom PO. Elicitors of PO activity (sodium dodecyl sulfate and trypsin) had no or a modest effect (increase) on the ability of venom, or larval and pupal plasma to trigger melanization reactions. SDS-PAGE separation of crude venom followed by in-gel staining using L-DOPA as a substrate revealed two venom proteins with PO activity with estimated molecular weights of 68 and 160 kDa. In vitro assays using BTI-TN-5B1-4 cells were performed to determine the importance of venom PO in triggering cellular changes and evoking cell death. When cell monolayers were pre-treated with 10 mM PTU or PMSF prior to venom exposure, the cells were protected from the effects of venom intoxication as evidenced by no observable cellular morphological changes and over 90% cell viability by 24 h after venom treatment. Simultaneous addition of inhibitors with venom or lower concentrations of PMSF were less effective in affording protection. These observations collectively argue that wasp venom PO is unique from that of the fly hosts, and that the venom enzyme is critical in the intoxication pathway leading to cell death. PMID:17054979

Abt, Michael; Rivers, David B

2007-02-01

350

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

Microsoft Academic Search

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

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

2009-01-01

351

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

Federal Register 2010, 2011, 2012, 2013

...includes the statement: ``Young infants have limited head and neck control.'' To reduce the amount of information on the...the same information is implied by other references to head control in the warning, so limiting that statement...

2013-06-24

352

Quantization of a Friedmann-Robertson-Walker model in N = 1 supergravity with gauged supermatter  

Microsoft Academic Search

The theory of N = 1 supergravity with gauged supermatter is studied in the context of a k = + 1 Friedmann minisuperspace model. It is found by imposing the Lorentz and supersymmetry constraints that there are {\\\\seveni no} physical states in the particular SU(2) model studied.

A. D. Y. Cheng; P. D. D'Eath; P. R. L. V. Moniz

1995-01-01

353

75 FR 35279 - Revocation of Regulations Banning Certain Baby-Walkers  

Federal Register 2010, 2011, 2012, 2013

...toes, or other parts of the anatomy of young children. The regulation...toe, or other part of the anatomy that could then be injured...or any other part of the anatomy, are guarded or otherwise...otherwise injuring portions of the human body when in normal use...

2010-06-21

354

Imaging of stepped frequency continuous wave GPR data using the Yule-Walker parametric method  

Microsoft Academic Search

Ground penetrating radar for humanitarian demining has a large bandwidth. It should discriminate small objects against a complex background. The stepped frequency continuous wave radar of IRCTR has a synthesized bandwidth of 4.5 GHz. Classical methods for generating an image of the subsurface include synthetic aperture processing for cross-range resolution and inverse Fourier transform to generate the range profile. This

Piet van Genderen; Ioan Nicolaescu

2005-01-01

355

Ball walker: A case study of humanoid robot locomotion in non-stationary environments  

Microsoft Academic Search

This paper presents a control framework for a biped robot to maintain balance and walk on a rolling ball. The control framework consists of two primary components: a balance controller and a footstep planner. The balance controller is responsible for the balance of the whole system and combines a state-feedback controller designed by pole assignment with an observer to estimate

Yu Zheng; Katsu Yamane

2011-01-01

356

Neurocutaneous melanosis and the Dandy–Walker complex: an uncommon but not so insignificant association  

Microsoft Academic Search

Background  Neurocutaneous melanosis represents a rare congenital but nonheritable phakomatosis defined as the association of giant or\\u000a multiple congenital nonmalignant melanocytic nevi with leptomeningeal melanosis or melanoma of the central nervous system.\\u000a \\u000a \\u000a \\u000a Methods  We describe the case of an adolescent with a giant congenital bathing trunk melanocytic nevus who developed progressive intracranial\\u000a hypertension due to leptomeningeal melanosis confirmed by surgical biopsy. Brain

Dominique Marnet; Matthieu Vinchon; Keyvan Mostofi; Benoit Catteau; Olivier Kerdraon; Patrick Dhellemmes

2009-01-01

357

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

PubMed Central

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.

Schaefer, Sabine; Lindenberger, Ulman

2013-01-01

358

Multiple mating and its effects in the lightbrown apple moth, Epiphyas postvittana (Walker)  

Microsoft Academic Search

Multiple mating and some of its effects were investigated in the tortricid moth, Epiphyas postvittana, a species in which females are generally monandrous. Males were capable of mating a relatively large number of times (mean of 6.6 matings throughout their lifetime). Although less common, multiple mating of females occurred and was related to the male that the female mated with

S. P. Foster; R. H. Ayers

1996-01-01

359

Immune response of Chilo suppressalis Walker (Lepidoptera: Crambidae) larvae to different entomopathogenic fungi.  

PubMed

The current study reports mortality and effects on cellular immune response of several entomopathogenic fungi including isoleates BB1, BB2 and BB3 of Beauveria bassiana, Metarhizium anisopliae, Isaria fumosoroseus and Lecanicilium lecanii against larvae of Chilo suppressalis. Prohemocytes, granulocytes, plasmatocytes and oenocytoids were identified as the main circulating hemocytes in the hemolymph of larvae using Giemsa staining solution. Entomopathogenic fungi caused differential mortality on larvae: BB1, BB3, M. anisopliae lead to the highest mortality on larvae and L. lecanii caused the lowest mortality. The highest numbers of total hemocytes were observed 3 h post-injection of B. bassiana isolates and 6 h for the other treatments. The highest numbers of plasmatocytes were observed 3 h post-injection of BB1 and Tween 80, whereas BB2, BB3, M. anisopliae, I. fumosoroseus and L. lecani caused plasmatocyte increase 6 h post-injection. Similar results were obtained in case of granulocytes but only Tween 80 showed the highest number of hemocytes 3 h post-injection. The highest numbers of nodules were found at various time intervals after injection of fungal isolates and latex bead. The highest activities of phenoloxidase were observed 12 h post-injection by BbB1, BbB3, M. anisopliae and latex bead; 3-6 h post-injection by BbB2, 6 h post-injection by I. fumosoroseus and 3-6 h post-injection by L. lecanii. Our data demonstrate the possibility of utilizing different fungal extracts in the field to help reduce the risk of resistance evolution in C. suppressalis and encourage experimentations aimed to increase the number of biological control agent for insect pests such as the striped rice stem borer C. suppressalis. PMID:24447729

Zibaee, A; Malagoli, D

2014-04-01

360

Walker Readiness Test for Disadvantaged Pre-School Children; Forms A and B.  

ERIC Educational Resources Information Center

This instrument assesses readiness for school in preschool disadvantaged children. Two forms, A and B, are available and it is recommended that one be used as a diagnostic pretest and the other as a progress measure. The test is an individually administered, non-verbal, untimed, but paced instrument. The child responds to questions, given in…

Walker, Wanda

361

In Lieu Of Myth. Airmen in Joint Ground Operations (Walker Paper, Number 13).  

National Technical Information Service (NTIS)

The US Army and Marine Corps find themselves increasingly unable to fill combat-support and combat-service-support (CS/CSS) positions in Operations Iraqi Freedom and Enduring Freedom. To compensate, the Joint Staff has tasked the Air Force to deploy signi...

D. W. Marttala

2009-01-01

362

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

Federal Register 2010, 2011, 2012, 2013

...Accreditation of Third Party Conformity Assessment Bodies AGENCY: Consumer Product Safety...accreditation of third party conformity assessment bodies for testing pursuant to specific...accreditation of third party conformity assessment bodies to assess conformity with...

2010-06-21

363

Male Remating Behavior and Its Effect on Female Reproductive Fitness in Cnephasia jactatana Walker (Lepidoptera: Tortricidae)  

Microsoft Academic Search

Male remating behavior and its effect on the female reproductive fitness of a New Zealand leafroller, Cnephasia jactatana, were investigated in the laboratory. With a recovery period of at least 24 h between matings, most males were able to mate four times and only about 25% could mate six times during their lifespan. Only 5% of males managed to mate

Alfredo Jiménez-Pérez; Qiao Wang

2004-01-01

364

Tightrope walkers and solidarity sisters: critical workplace educators in the garment industry  

Microsoft Academic Search

This article focuses on the complex negotiations of critical workplace educators positioned amongst contradictory agendas and discourses in the workplace. While philosophically aligned with critical pedagogical agendas of transformation and collective action for workplace change, these educators perform an array of pedagogic articulations in everyday practice to secure their continued presence in the workplace. What becomes evident in these seemingly

Tara Fenwick

2007-01-01

365

Tightrope Walkers and Solidarity Sisters: Critical Workplace Educators in the Garment Industry  

ERIC Educational Resources Information Center

This article focuses on the complex negotiations of critical workplace educators positioned amongst contradictory agendas and discourses in the workplace. While philosophically aligned with critical pedagogical agendas of transformation and collective action for workplace change, these educators perform an array of pedagogic articulations in…

Fenwick, Tara

2007-01-01

366

Spatial foraging in free ranging bearded sakis: Traveling salesmen or Lévy walkers?  

PubMed

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. Am. J. Primatol. 76:472-484, 2014. © 2013 Wiley Periodicals, Inc. PMID:24166852

Shaffer, Christopher A

2014-05-01

367

Changes in Step Variability of New Walkers With Typical Development and With Down Syndrome  

Microsoft Academic Search

Models of human gait are based on adult locomotion. C. E. Bauby and A. D. Kuo (2000) proposed that adults rely on passive mechanisms at the spinal level to control motion in the anteroposterior direction and rely on direct monitoring of postural control in the lateral direction. The authors' purpose in this study was to determine if that model applies

Julia Looper; Jianhua Wu; Rosa Angulo Barroso; Dale Ulrich; Beverly D. Ulrich

2006-01-01

368

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

ERIC Educational Resources Information Center

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…

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

2011-01-01

369

Cortical Regions for Judgments of Emotions and Personality Traits from Point-light Walkers  

Microsoft Academic Search

Humans are able to use nonverbal behavior to make fast, reliable judgments of both emotional states and personality traits. Whereas a sizeable body of research has identified neural structures critical for emotion recognition, the neural substrates of personality trait attribution have not been explored in detail. In the present study, we investigated the neural systems involved in emotion and personality

Andrea S. Heberlein; Ralph Adolphs; Daniel Tranel; Hanna Damasio

2004-01-01

370

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

NASA Astrophysics Data System (ADS)

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.

Kim, In Chan; Cule, Dinko; Torquato, Salvatore

2000-04-01

371

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

Microsoft Academic Search

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

Dinko Cule; Salvatore Torquato

2000-01-01

372

Controlled surface-induced flows from the motion of self-assembled colloidal walkers  

PubMed Central

Biological flows at the microscopic scale are important for the transport of nutrients, locomotion, and differentiation. Here, we present a unique approach for creating controlled, surface-induced flows inspired by a ubiquitous biological system, cilia. Our design is based on a collection of self-assembled colloidal rotors that “walk” along surfaces in the presence of a rotating magnetic field. These rotors are held together solely by magnetic forces that allow for reversible assembly and disassembly of the chains. Furthermore, rotation of the magnetic field allows for straightforward manipulation of the shape and motion of these chains. This system offers a simple and versatile approach for designing microfluidic devices as well as for studying fundamental questions in cooperative-driven motion and transport at the microscopic level.

Sing, Charles E.; Schmid, Lothar; Schneider, Matthias F.; Franke, Thomas; Alexander-Katz, Alfredo

2010-01-01

373

Brownian motion in Robertson-Walker spacetimes from electromagnetic vacuum fluctuations  

SciTech Connect

We consider the effects of the vacuum fluctuations of a quantized electromagnetic field on particles in an expanding universe. We find that these particles typically undergo Brownian motion and acquire a nonzero mean squared velocity that depends on the scale factor of the universe. This Brownian motion can be interpreted as due to noncancellation of anticorrelated vacuum fluctuations in the time-dependent background spacetime. Alternatively, one can interpret this effect as the particles acquiring energy from the background spacetime geometry, a phenomenon that cannot occur in a static spacetime. We treat several types of coupling between the electromagnetic field and the particles and several model universes. We also consider both free particles, which, on the average, move on geodesics, and particles in bound systems. There are significant differences between these two cases, which illustrates that nongeodesic motion alters the effects of the vacuum fluctuations. We discuss the possible applications of this Brownian motion effect to cosmological scenarios.

Bessa, Carlos H. G. [Departamento de Fisica, Universidade Federal da Paraiba, Joao Pessoa, Paraiba 58051-970 (Brazil); Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States); Bezerra, V. B. [Departamento de Fisica, Universidade Federal da Paraiba, Joao Pessoa, Paraiba 58051-970 (Brazil); Ford, L. H. [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States)

2009-06-15

374

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

375

Canada thistle biological control agents on two South Dakota wildlife refuges  

USGS Publications Warehouse

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

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

2006-01-01

376

Rufous-tailed jacamars and aposematic butterflies: do older birds attack novel prey?  

Microsoft Academic Search

Although avian predators are thought to drive the evolution of warning-color mimicry in butterflies, few empirical studies directly address this assumption from the predator's perspective. Heliconius butterflies are textbook examples of Mullerian mimicry, with perhaps the most remarkable example being the Heliconius erato and Heliconius melpomene mimicry complex. Rufous-tailed jacamars, Galbula ruficauda (Galbulidae), are well-known butterfly predators and provide an

Gary M. Langham

2006-01-01

377

Rufous-tailed jacamars and aposematic butterflies: do older birds attack novel prey?  

Microsoft Academic Search

Although avian predators are thought to drive the evolution of warning-color mimicry in butterflies, few empirical studies directly address this assumption from the predator's perspective. Heliconius butterflies are textbook examples of Mullerian mimicry, with perhapsthe mostremarkable example beingtheHeliconiuseratoandHeliconius melpomenemimicrycomplex. Rufous-tailedjacamars, Galbula ruficauda (Galbulidae), are well-known butterfly predators and provide an excellent study organism to investigate patterns of attack behavior in

Gary M. Langham

2005-01-01

378

PTC-6 vacuum system: WallWalker(trademark) and Blastrac(reg-sign) shot blast cleaning system.  

National Technical Information Service (NTIS)

The LTC Americas, Inc. wall decontamination technology consisted of two pneumatic hand-held tools: (1) a roto-peen scaler that used star cutters and (2) a 3-piston hammer with reciprocating bits. The hand-held tools were used in conjunction with the LTC P...

1998-01-01

379

76 FR 13665 - Arcelor Mittal, Formerly Known as Mittal Steel Walker Wire, a Subsidiary of Arcelor Mittal...  

Federal Register 2010, 2011, 2012, 2013

...Including On-Site Leased Workers From Leasing Systems, Ferndale, MI; Amended Certification...including on-site leased workers from Leasing Systems, Inc., Ferndale, Michigan...including on- site leased workers from Leasing Systems, Inc., Ferndale,...

2011-03-14

380

Premolis semirufa (Walker, 1856) Envenomation, Disease Affecting Rubber Tappers of the Amazon: Searching for Caterpillar-Bristles Toxic Components  

PubMed Central

Background The caterpillar of the moth Premolis semirufa (Lepidoptera: Arctiidae), commonly named Pararama, is endemic of the Amazon basin. Accidental contact with these caterpillar bristles causes local symptoms such as intense heat, pain, edema and itching which last for three to seven days; however, after multiples contacts, it may induce joint-space narrowing and bone alteration, as well as degeneration of the articular cartilage and immobilization of the affected joints. Specific treatment for this disease does not exist, but corticosteroids are frequently administered. Despite of the public health hazard of Premolis semirufa caterpillar poisoning, little is known about the nature of the toxic components involved in the induction of the pathology. Methodology/Principal Findings Here we have investigated the biological and immunochemical characteristics of the caterpillar's bristles components. Analysis of the bristles extract in in vitro assays revealed the presence of proteolytic and hyaluronidase activities but no phospholipase A2 activity. In vivo, it was observed that the bristles extract is not lethal but can induce an intense inflammatory process, characterized by the presence of neutrophils in the paw tissues of injected mice. Furthermore, the bristles components stimulated an intense and specific antibody response but autoantibodies such as anti-DNA or anti-collagen type II were not detected. Conclusion The results suggest that Premolis semirufa caterpillar bristles secretion contains a mixture of different enzymes that may act together in the generation and development of the clinical manifestations of the Pararama envenomation. Moreover, the high immunogenicity of the caterpillar bristles components, as shown by the generation of high antibody titers, may also contribute to the induction and establishment of the inflammatory disease.

Villas-Boas, Isadora Maria; Goncalves-de-Andrade, Rute Maria; Pidde-Queiroz, Giselle; Assaf, Suely Lucia Muro Rais; Portaro, Fernanda C. V.; Sant'Anna, Osvaldo A.; van den Berg, Carmen W.; Tambourgi, Denise V.

2012-01-01

381

Effects of a Selectively Reduced Gizzard Shad Population on Trophic Interactions and Age0 Fishes in Walker County Lake, Alabama  

Microsoft Academic Search

Within 2 years of a December 1995 reduction in a population of gizzard shad Dorosoma cepedianum in a 66-ha public fishing reservoir, their abundance rapidly returned to high levels. During 1996, age-0 gizzard shad density was low, and they experienced rapid growth as larvae and juveniles, achieving average lengths (±SE) of 236 ± 7 mm total length (TL) by 13

Gene W. Kim; Dennis R. DeVries

2000-01-01

382

Development of posterior walker with adjustable visual cues to improve gait performance for patients with Parkinson's disease  

Microsoft Academic Search

Background: To improve gait performance and safety for patients with Parkinson's disease, external stimuli or walking aids are used. It was found that external visual stimuli were most effective. However, external visual stimuli mostly were applicable in particular places only. Therefore in daily life, there is no effective walking aid for PD patients to use in daily environment. Purpose: This

H.-K. Wu; H.-R. Chen; C.-H. Yu

2010-01-01

383

Replacement by Caenis Diminuta Walker (Ephemeroptera:Caenidae) in the Mayfly Community Structure of a Thermally-Stressed, Southeastern Stream.  

National Technical Information Service (NTIS)

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 exp 0 C) accu...

N. L. Poff R. A. Matthews

1984-01-01

384

Combined endurance and resistance circuit training in highly trained\\/top-level female race walkers: a case report  

Microsoft Academic Search

Race walking can be considered as a long-distance performance and it can be described as the technical and athletic expression\\u000a of fast walking. The physiological determinants of these performances have been well documented; moreover, several recent\\u000a studies demonstrated that concurrent strength and endurance training can improve performance in endurance athletes. Thus,\\u000a the purpose of this report was to monitor the

Antonio La Torre; Gianluca Vernillo; Pierluigi Fiorella; Clara Mauri; Luca Agnello

2008-01-01

385

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

Federal Register 2010, 2011, 2012, 2013

...process for the EIS. Comments on issues may be submitted in writing until...process is to determine relevant issues that will influence the scope of...identified the following preliminary issues: Social and economic impacts,...

2010-08-13

386

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

Microsoft Academic Search

Observations and simulations link anthropogenic greenhouse and aerosol emissions with rapidly increasing Indian Ocean sea\\u000a surface temperatures (SSTs). Over the past 60 years, the Indian Ocean warmed two to three times faster than the central tropical\\u000a Pacific, extending the tropical warm pool to the west by ~40° longitude (>4,000 km). This propensity toward rapid warming\\u000a in the Indian Ocean has been the

A. Park Williams; Chris Funk

387

Evaluation of Unrestrained Replica-Exchange Simulations Using Dynamic Walkers in Temperature Space for Protein Structure Refinement  

PubMed Central

A central problem of computational structural biology is the refinement of modeled protein structures taken from either comparative modeling or knowledge-based methods. Simulations are commonly used to achieve higher resolution of the structures at the all-atom level, yet methodologies that consistently yield accurate results remain elusive. In this work, we provide an assessment of an adaptive temperature-based replica exchange simulation method where the temperature clients dynamically walk in temperature space to enrich their population and exchanges near steep energetic barriers. This approach is compared to earlier work of applying the conventional method of static temperature clients to refine a dataset of conformational decoys. Our results show that, while an adaptive method has many theoretical advantages over a static distribution of client temperatures, only limited improvement was gained from this strategy in excursions of the downhill refinement regime leading to an increase in the fraction of native contacts. To illustrate the sampling differences between the two simulation methods, energy landscapes are presented along with their temperature client profiles.

Olson, Mark A.; Lee, Michael S.

2014-01-01

388

Leaf development in Xylopia aromatica (Lam) Mart. (Annonaceae): implications for palatability to Stenoma scitiorella Walker 1864 (Lepidoptera: Elachistidae).  

PubMed

Variations in specific foliar mass and water content, nitrogen, soluble carbohydrates and tannins were studied during the growth and maturation processes of the Xylopia aromatica leaves, to determine the effects of such alterations on the herbivory of Stenoma scitiorella caterpillars. This work was carried out in the physiognomy of the typical cerrado of the Parque Estadual de Vassununga, Gleba Pé-de Gigante, Santa Rita do Passa Quatro, São Paulo State, Brazil. While nutritional quality (water and nitrogen) decreases during expansion and maturation of Xylopia aromatica leaves, the chemical (tannins) and physical (sclerophylly) defenses are raised. In agreement with the observations on herbivory, the results support the hypothesis that the reduction in palatability and increase in chemical defenses of Xylopia aromatica leaves account for the caterpillars' preference for young expanding leaves. PMID:19197502

Varanda, E M; Costa, A A; Barosela, J R

2008-11-01

389

PTC-6 vacuum system: WallWalker{trademark} and Blastrac{reg_sign} shot blast cleaning system  

SciTech Connect

The LTC Americas, Inc. wall decontamination technology consisted of two pneumatic hand-held tools: (1) a roto-peen scaler that used star cutters and (2) a 3-piston hammer with reciprocating bits. The hand-held tools were used in conjunction with the LTC PTC-6 vacuum system which captured dust and debris as the wall decontamination took place. Recommendations for improved worker safety and health during use of the PTC-6 vacuum system with hand-held tools include: (1) keeping all hoses and lines as orderly as possible in compliance with good housekeeping requirements; (2) ergonomic training to include techniques in lifting, bending, stooping, twisting, etc.; (3) use of a clamping system to hold hoses to the vacuum system; (4) a safety line on the air line connections; (5) use of a mechanical lifting system for waste drum removal; and (6) the use of ergonomically designed tools.

NONE

1998-02-01

390

My Body, My World: Illness and Identity in Alice Walker's "Beauty: When the Other Dancer Is the Self  

ERIC Educational Resources Information Center

Writing Center faculty at the Medical University of South Carolina teach humanities courses in which we include literary texts that are not ostensibly "about health care" to introduce to students how unique an illness narrative can be--to challenge, in fact, preconceived notions student may have about what "counts" as a…

Kerr, Lisa

2013-01-01

391

Disruption of pupariation and eclosion behavior in the flesh fly, Sarcophaga bullata Parker (Diptera: Sarcophagidae), by venom from the ectoparasitic wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae).  

PubMed

The action of venom from the ectoparasitic wasp, Nasonia vitripennis, was monitored by examining alterations in patterned muscular movements characteristic of pupariation and eclosion behavior in the flesh fly, Sarcophaga bullata. Venom injected into larvae prior to pupariation caused a dose-dependent delay in pupariation. Eventually, such larvae did pupariate, but puparia were abnormally formed. Barographic records revealed that all elements of pupariation behavior were present in venom-injected larvae, but pupariation behavior was not well synchronized with tanning, thus implying that the venom caused disruption in the temporal organization of central motor programs. When larvae were ligated and injected with venom posterior to the ligature, no response was evident in the posterior region, suggesting that the venom does not directly stimulate muscles or neuromuscular junctions. Injection of exogenous ecdysteroid into venom-injected larvae restored some elements of pupariation behavior, consistent with ecdysone's role in stimulating the release of anterior retraction factor and puparium tanning factor, two factors that are released from the CNS to regulate pupariation. When the venom was injected into newly emerged imagoes, the duration of extrication behavior was shortened, whereas all phases of post-eclosion behavior were lengthened. These observations imply that the venom affects CNS centers that regulate the muscular systems engaged in extrication and post-eclosion behavior. PMID:15378569

Rivers, David B; Zdarek, Jan; Denlinger, David L

2004-10-01

392

The ectoparasitic wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) differentially affects cells mediating the immune response of its flesh fly host, Sarcophaga bullata Parker (Diptera: Sarcophagidae).  

PubMed

In this study, we examined cellular immune responses in the flesh fly, Sarcophaga bullata, when parasitized by the ectoparasitoid Nasonia vitripennis. In unparasitized, young pharate adults and third instar, wandering larvae of S. bullata, four main hemocyte types were identified by light microscopy: plasmatocytes, granular cells, oenocytoids, and pro-hemocytes. Parasitism of young pharate adults had a differential effect on host hemocytes; oenocytoids and pro-hemocytes appeared to be unaltered by parasitism, whereas adhesion and spreading behavior were completely inhibited in plasmatocytes and granular cells by 60 min after oviposition. The suppression of spreading behavior in granular cells lasted the duration of parasitism. Plasmatocytes were found to decline significantly during the first hour after parasitism and this drop was attributed to cell death. Melanization and clotting of host hemolymph did not occur in parasitized flies, or the onset of both events was retarded by several hours in comparison to unparasitized pharate adults. Hemocytes from envenomated flies were altered in nearly identical fashion to that observed for natural parasitism; the total number of circulating hemocytes declined sharply by 60 min post-envenomation, the number of plasmatocytes declined but not granular cells, and the ability of plasmatocytes and granular cells to spread when cultured in vitro was abolished within 1 h. As with parasitized hosts, the decrease in plasmatocytes was due to cell death, and inhibition of spreading lasted until the host died. Isolated crude venom also blocked adhesion and spreading of these hemocyte types in vitro. Thus, it appears that maternally derived venom disrupts host immune responses almost immediately following oviposition and the inhibition is permanent. The possibility that this ectoparasite disables host defenses to afford protection to feeding larvae and adult females is discussed. PMID:12770028

Rivers, D B.; Ruggiero, L; Hayes, M

2002-11-01

393

The ectoparasitic wasp Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) differentially affects cells mediating the immune response of its flesh fly host, Sarcophaga bullata Parker (Diptera: Sarcophagidae)  

Microsoft Academic Search

In this study, we examined cellular immune responses in the flesh fly, Sarcophaga bullata, when parasitized by the ectoparasitoid Nasonia vitripennis. In unparasitized, young pharate adults and third instar, wandering larvae of S. bullata, four main hemocyte types were identified by light microscopy: plasmatocytes, granular cells, oenocytoids, and pro-hemocytes. Parasitism of young pharate adults had a differential effect on host

D. B. Rivers; L. Ruggiero; M. Hayes

2002-01-01

394

Late Cenozoic strike-slip faulting in the NE Mojave Block: Deformation at the southwest boundary of the Walker Lane belt  

SciTech Connect

New structural and stratigraphy data from the NE Mojave Block (NEMB) establish the timing and style of Cenozoic deformation south of the Garlock fault and west of the Avawatz Mts. Unlike adjacent areas, most of the NEMB did not undergo early-mid Miocene extension. Major fault zones strike EW; offset markers and small-scale shear criteria indicate left-lateral strike slip with a small reverse component. Lateral offsets average ca. 1--6 km and vertical offset is locally >200m. Pre-Tertiary markers indicate minimum cumulative sinistral shear of ca. 15 km in the area between the Garlock and Coyote Lake faults. Tertiary strata are deformed together with the older rocks. Along the Ft. Irwin fault, alluvial fan deposits interpreted to be <11Ma appear to be displaced as much as Mesozoic igneous rocks. EW sinistral faults S. of the Garlock fault cut unconsolidated Quaternary deposits; geomorphologic features and trench exposures along segments of the McLean Lake fault and the Tiefort Mt. fault suggest Late Quaternary activity. The EW faults do not cut modern drainages and are not seismically active. NW-striking faults are largely absent within the NEMB; the largest faults bound the domain of EW-striking faults. Offset of Cretaceous and Miocene rocks suggests the W boundary (Goldstone Lake fault) has <2km right separation. Along the E boundary (Soda-Avawatz fault zone), the presence of distinctive clasts in mid-late Miocene conglomerates west of the Avawatz Mts. supports the suggestion of Brady (1984) of ca. 20 km dextral displacement. Other NW-striking faults are cut by EW faults, have unknown or minor dextral displacement (Desert King Spring Fault, Garlic Spring fault) or are low- to moderate-angle left-oblique thrust faults (Red Pass Lake fault zone).

Schermer, E.R. (Western Washington Univ., Bellingham, WA (United States). Geology Dept.)

1993-04-01

395

March 17 - 19, 2004: caBIG Architecture Kickoff Meeting Presentation, Mark Thornquist, Derek Walker, Heather Kincaid, Rahul Joshi, Dan Geraghty, Robert Robbins  

Cancer.gov

Generalizing the Data over a grid Interface logicdata External Database Export Local Database Publication Control System y Safe Export y Export Schema y Mapping tools y Self Documenting Schema y Exposed APIs y Auxiliary Data Supported y Identity Management Support y Access Case Compliant caBIG Architecture Kickoff Meeting Presentation Fred Hutchinson Cancer Research Center DMCC UT San Antonio H.

396

Implementation of the Secondary 3 Program of Project P.A.T.H.S.: observations based on the co-walker scheme.  

PubMed

The present study was conducted to explore the implementation quality of the Secondary 3 Program of the Tier 1 Program of Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes) in the third year of the Full Implementation Phase. Classroom observations of 182 units in 129 schools were conducted. Results showed that the overall level of program adherence was 73.9%. Thirteen aspects concerning program delivery were significantly correlated. Multiple regression analyses revealed that overall implementation quality was significantly predicted by student participation and involvement, strategies to enhance student motivation, use of positive and supportive feedback, degree of achievement of the objectives, and lesson preparation. Success of implementation was significantly predicted by student participation and involvement, classroom control, use of positive and supportive feedback, opportunity for reflection, degree of achievement of the objectives and time management. The present findings generally suggest that the implementation quality of Project P.A.T.H.S. was high. PMID:22962208

Shek, Daniel T L; Ma, Cecilia M S

2012-01-01

397

Implementation of the Project P.A.T.H.S. in Hong Kong: observations based on the Co-Walker Scheme.  

PubMed

The implementation quality of the Tier 1 Program (Secondary 1 Program) of the Project P.A.T.H.S. in the third year of the Full Implementation Phase was examined in this study, with classroom observations of 233 units in 157 schools. Results demonstrated that the overall level of program adherence was generally high with an average of 72.96%. A total of 13 aspects regarding program delivery were significantly correlated. Multiple regression analyses indicated that overall implementation quality was significantly predicted by student participation and involvement, classroom control, use of positive and supportive feedback, degree of achievement of the objectives, and time management. Student participation and involvement, classroom control, degree of achievement of the objectives, and time management were significant predictors of success of implementation. PMID:22416504

Shek, Daniel T L; Ng, Catalina S M; Toh, Louis P F

2011-01-01

398

Different roles suggested by sex-biased expression and pheromone binding affinity among three pheromone binding proteins in the pink rice borer, Sesamia inferens (Walker) (Lepidoptera: Noctuidae).  

PubMed

Pheromone binding proteins (PBPs) are thought to bind and transport hydrophobic sex pheromone molecules across the aqueous sensillar lymph to specific pheromone receptors on the dendritic membrane of olfactory neurons. A maximum of 3 PBP genes have been consistently identified in noctuid species, and each of them shares high identity with its counterparts in other species within the family. The functionality differences of the 3 proteins are poorly understood. In the present study, 3 PBP cDNAs (SinfPBP1, 2, 3) were identified from the pink rice borer, Sesamia inferens, for the first time. The quantitative real-time PCR indicated that the 3 PBPs displayed similar temporal but very different sex related expression profiles. Expression of SinfPBP1 and SinfPBP2 were highly and moderately male biased, respectively, while SinfPBP3 was slightly female biased, as SinfPBPs were expressed at very different levels (PBP1>PBP2?PBP3) in male antennae, but at similar levels in female antennae. Furthermore, the 3 SinfPBPs displayed different ligand binding profiles in fluorescence competitive binding assays. SinfPBP1 exhibited high and similar binding affinities to all 3 sex pheromone components (Ki=0.72-1.60?M), while SinfPBP2 showed selective binding to the alcohol and aldehyde components (Ki=0.78-1.71?M), and SinfPBP3 showed no obvious binding to the 3 sex pheromone components. The results suggest that SinfPBP1 plays a major role in the reception of female sex pheromones in S. inferens, while SinfPBP3 plays a least role (if any) and SinfPBP2 functions as a recognizer of alcohol and aldehyde components. PMID:24862154

Jin, Jun-Yan; Li, Zhao-Qun; Zhang, Ya-Nan; Liu, Nai-Yong; Dong, Shuang-Lin

2014-07-01

399

Effects of host species, stage and size on the sex ratio and clutch size of the parasitoid, Dibrachys boarmiae (Walker, 1863) (Hymenoptera: Pteromalidae).  

PubMed

Effects of host species, stage and size on clutch size and sex ratio of the gregarious, idiobiont ectoparasitoid Dibrachys boarmiae were investigated at 25±2°C and 70±5% relative humidity. The greater wax moth, Galleria mellonella, small wax moth, Achroia grisella, and early stage solitary larvae of the endoparasitoid, Apanteles galleriae, were used as hosts. Clutch size was greatest from prepupae of the largest host, Galleria mellonella, with a mean of 40.07 offspring per host versus 14.73 and 2.93 for Achroia grisella and Apanteles galleriae, respectively. The mean clutch size from pupae was lower than from prepupae, being 17.27, 10.73 and 2.89 for Galleria mellonella, Achroia grisella and Apanteles galleriae, respectively. Within each host species and stage, heavier hosts resulted in larger clutches. The sex ratio of offspring (proportion of male) was approximately 0.20, with only minor differences among host species, stages and sizes. PMID:21208507

Sarikaya, A; Gülel, A

2011-06-01

400

Geologic application of thermal inertia imaging using HCMM data. [Walker Lane, Nevada; San Rafael, Utah; and Death Valley and Pisgah Crater, Lavic Lake Region, California  

NASA Technical Reports Server (NTRS)

Three test sites in the western US were selected to discriminate among surface geologic materials on the basis of their thermal properties as determined from HCMM data. Attempts to determine quantitatively accurate thermal inertia values from HCMM digital data met with only partial success due to the effects of sensor miscalibrations, radiative transfer in the atmosphere, and varying meteorology and elevation across a scene. In most instances, apparent thermal inertia was found to be an excellent qualitative representation of true thermal inertia. Computer processing of digital day and night HCMM data allowed construction of geologically useful images. At some test sites, more information was provided by data than LANDSAT data. Soil moisture effects and differences in spectrally dark materials were more effectively displayed using the thermal data.

Kahle, A. B.; Schieldge, J. P.; Abrams, M. J.; Alley, R. E.; Levine, C. J. (principal investigators)

1981-01-01

401

Putative Pathway of Sex Pheromone Biosynthesis and Degradation by Expression Patterns of Genes Identified from Female Pheromone Gland and Adult Antenna of Sesamia inferens (Walker).  

PubMed

The general pathway of biosynthesis and degradation for Type-I sex pheromones in moths is well established, but some genes involved in this pathway remain to be characterized. The purple stem borer, Sesamia inferens, employs a pheromone blend containing components with three different terminal functional groups (Z11-16:OAc, Z11-16:OH, and Z11-16:Ald) of Type-I sex pheromones. Thus, it provides a good model to study the diversity of genes involved in pheromone biosynthesis and degradation pathways. By analyzing previously obtained transcriptomic data of the sex pheromone glands and antennae, we identified 73 novel genes that are possibly related to pheromone biosynthesis (46 genes) or degradation (27 genes). Gene expression patterns and phylogenetic analysis revealed that one desaturase (SinfDes4), one fatty acid reductase (SinfFAR2), and one fatty acid xtransport protein (SinfFATP1) genes were predominantly expressed in pheromone glands, and clustered with genes involved in pheromone synthesis in other moth species. Ten genes including five carboxylesterases (SinfCXE10, 13, 14, 18, and 20), three aldehyde oxidases (SinfAOX1, 2 and 3), and two alcohol dehydrogenases (SinfAD1 and 3) were expressed specifically or predominantly in antennae, and could be candidate genes involved in pheromone degradation. SinfAD1 and 3 are the first reported alcohol dehydrogenase genes with antennae-biased expression. Based on these results we propose a pathway involving these potential enzyme-encoding gene candidates in sex pheromone biosynthesis and degradation in S. inferens. This study provides robust background information for further elucidation of the genetic basis of sex pheromone biosynthesis and degradation, and ultimately provides potential targets to disrupt sexual communication in S. inferens for control purposes. PMID:24817326

Zhang, Ya-Nan; Xia, Yi-Han; Zhu, Jia-Yao; Li, Sheng-Yun; Dong, Shuang-Lin

2014-05-01

402

Principal Facts, Accuracies, Sources, Base Station Descriptions, and Plots for 832 Gravity Stations on the Walker Lake 1 degree x 2 degrees Quadrangle, California and Nevada.  

National Technical Information Service (NTIS)

Included in the report is a brief summary of the format used, station name and location plots at scale of 1:250,000 and 1:32,000, and descriptions for 3 base stations. All of the gravity stations have been reduced to complete Bouguer anomalies. A discussi...

S. L. Robbins H. W. Oliver

1976-01-01

403

Lifetime gains and patterns of accumulation and mobilization of nutrients in females of the synovigenic parasitoid, Diglyphus isaea Walker (Hymenoptera: Eulophidae), as a function of diet.  

PubMed

In nature, adult parasitoids feed to obtain and use nutrients for supplementing and/or replenishing some of their existing array of nutrient reserves. When adults feed on host or non-host food, they can enhance fitness, typically by increasing egg production or longevity. In the present study, ovigeny index (OI) and impact of female fitness, as well as physiological state on the reproductive strategies, were investigated in the synovigenic parasitoid, Diglyphus isaea, fed on host food (2-3rd instars of Liriomyza sativae larvae), non-host foods (10% honey solution) and starved (distilled water, control). The results showed that D. isaea was a strongly synovigenic parasitoid, of which OI value was 0.002. Both types of food enhanced the fecundity and prolonged the longevity of the females. D. isaea females fed on non-host food showed higher levels of gut sugar, body sugar and glycogen than those fed on host food, but the levels of lipid were higher in the host-fed females. D. isaea females seemed to show lipogenesis, with low rates of lipid catabolism sufficient to satisfy the requirement of egg maturation. Females might absorb lipids directly from the haemolymph of paralyzed hosts. PMID:21641912

Zhang, Yi-bo; Liu, Wan-xue; Wang, Wei; Wan, Fang-hao; Li, Qiang

2011-07-01

404

Water Resources Data California, Water Year 1981: Vol. 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water resources data for the 1981 water year for California consists of records of stage, discharge, gage-height, and water quality of streams; stage, contents and water quality of lakes and reservoirs; water levels and water quality of wells. Volume 3 contains discharge records for 158 gaging stations; stage and contents for 50 lakes and reservoirs; gage height records for 2 lakes; water quality for 23 stations; water levels for 53 observation wells, and water quality for 7 wells. Also included are 11 crest-stage partial-record stations and two water-quality partial-record stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

U.S. Geological Survey

1982-01-01

405

Water resources data for California, water year 1980; Volume 3, Southern Central Valley basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Volume 3 of water resources data for the 1980 water year for California consists of records of stage, discharge, gage-height, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; water levels and water quality of wells. This report contains discharge records for 185 gaging stations; stage and contents for 39 lakes and reservoirs; gage-height records for 2 lakes; water quality for 62 stations; water levels for 56 observation wells. Also included are 11 crest-stage partial-record stations and one water-quality partial-record stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

U.S. Geological Survey

1981-01-01

406

Water Resources Data, California, Water Year 1997. Volume 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1997 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 170 gaging stations, stage and contents for 43 lakes and reservoirs, and water quality for 30 stations. Also included is 1 crest-stage partial-record station and 1 miscellaneous partial-record site. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Anderson, S. W.; Hayes, P. D.; Rockwell, G. L.

1998-01-01

407

Water Resources Data -- California, Water Year 2003, Volume 3. Southern Central Valley Basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 2003 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 185 gaging stations, stage and contents for 47 lakes and reservoirs, water quality for 45 stations and 13 partial-record stations, and precipitation data for 2 stations. Also included are 1 miscellaneous partial-record site and 1 crest-stage partial-record station. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Rockwell, G. L.; Pope, G. L.; Smithson, J. R.; Freeman, L. A.

2004-01-01

408

Water Resources Data, California, Water Year 1995. Volume 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water resources data for the 1995 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 3 contains discharge records for 167 streamflow-gaging stations, 1 crest-stage partial-record streamflow station; stage and contents records for 42lakes and reservoirs; water-quality records for 76 streamflow-gaging stations and 6 partialrecord stations; and precipitation records for 2 gaging stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey with other agencies.

Hayes, P. D.; Rockwell, G. L.; Anderson, S. W.

1996-01-01

409

Water Resources Data, California, Water Year 1996. Volume 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1996 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 168 gaging stations, stage and contents for 43 lakes and reservoirs, precipitation data for 2 stations, and water quality for 30 stations. Also included is 1 crest-stage partial-record station. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Rockwell, G. L.; Anderson, S. W.; Hayes, P. D.

1997-01-01

410

Water resources data for California, water year 1979; Volume 3: Southern Central Valley basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1979 water year for California consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; records of water levels in selected observation wells; and selected chemical analyses of ground water. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. These data, a contribution to the National Water Data System, were collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

California District of the Water Resources Division

1981-01-01

411

Water Resources Data--California, Water Year 2002, Volume 3. Southern Central Valley Basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 2002 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 183 gaging stations, stage and contents for 46 lakes and reservoirs, water quality for 39 stations and 12 partial-record stations, and precipitation data for 2 stations. Also included are 1 miscellaneous partial-record site and 1 crest-stage partial-record station. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Freeman, L. A.; Rockwell, G. L.; Pope, G. L.; Smithson, J. R.

2003-01-01

412

Water resources data for California, water year 1975; Volume 3: Southern Central Valley Basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1975 water year for California consist of records of streamflow and contents of reservoirs at gaging stations, partial-record stations, and miscellaneous sites; records of water quality including the physical, chemical, and biological characteristics of surface and ground water; and records of water levels in selected observation wells. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of Lee R. Peterson, district chief; Winchell Smith, assistant district chief for hydrologic data; and Leonard N. Jorgensen, chief of the basic data section. These data represent that part of the National Water Data System collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

U.S. Geological Survey

1976-01-01

413

Water resources data for California, water year 1977; Volume 3: Southern Central Valley basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1977 water year for California consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; records of water levels in selected observation wells; and selected chemical analyses of ground water. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of Winchell Smith, Assistant District Chief for Hydrologic Data and Leonard N. Jorgensen, Chief of the Basic-Data Section. These data, a contribution to the National Water Data System, were collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

California District of the Water Resources Division

1978-01-01

414

Water Resources Data, California, Water Year 1998. Volume 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1998 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 172 gaging stations, stage and contents for 43 lakes and reservoirs, and water quality for 36 stations. Also included is 1 crest-stage partial-record station and 3 miscellaneous partial-record site. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Hayes, P. D.; Rockwell, G. L.; Anderson, S. W.; Smithson, J. R.

1999-01-01

415

Water Resources Data--California, Water Year 2001, Volume 3. Southern Central Valley Basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 2001 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 180 gaging stations, stage and contents for 44 lakes and reservoirs, and water quality for 44 stations. Also included are 1 crest-stage partial-record station, 1 miscellaneous partial-record sites, and 6 miscellaneous-measurement stations. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Smithson, J. R.; Freeman, L. A.; Rockwell, G. L.; Anderson, S. W.; Pope, G. L.

2002-01-01

416

Water Resources Data, California, Water Year 1994. Volume 3. Southern Central Valley Basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water resources data for the 1994 water year for California consist of records of stage, discharge, and water quality of streams; stage and contents in lakes and reservoirs; and water levels and water quality in wells. Volume 3 contains discharge records for 178 streamflow-gaging stations, 3 crest-stage partial-record streamflow stations and 13 miscellaneous measurement stations; stage and contents records for 43 lakes and reservoirs; water-quality records for 49 streamflow-gaging stations and 18 partial-record stations; and precipitation records for one gaging station. These data represent that part of the National Water Data System operated by the U.S. Geological Survey with other agencies.

Anderson, S. W.; Hayes, P. D.; Rockwell, G. L.

1995-01-01

417

Water Resources Data--California, Water Year 2000, Volume 3. Southern Central Valley Basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 2000 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 175 gaging stations, stage and contents for 44 lakes and reservoirs, and water quality for 31 stations. Also included are 1 crest-stage partial-record station and 1 miscellaneous partial-record sites. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in California.

Anderson, S. W.; Smithson, J. R.; Freeman, L. A.; Rockwell, G. L.

2001-01-01

418

Water resources data for California, water year 1976; Volume 3, Southern Central Valley basins and the Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 1976 water year for California consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; records of water levels in selected observation wells; and selected chemical analyses of ground water. Records for a few pertinent streamflow and water-quality stations in bordering States are also included. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of Lee R. Peterson, district chief; Winchell Smith, assistant district chief for hydrologic data; and Leonard N. Jorgensen, chief of the basic-data section. These data, a contribution to the National Water Data System, were collected by the Geological Survey and cooperating local, State, and Federal agencies in California.

California District of the Water Resources Division

1977-01-01

419

Water resources data-California, water year 2004, volume 3. southern central valley basins and The Great Basin from Walker River to Truckee River  

USGS Publications Warehouse

Water-resources data for the 2004 water year for California consist of records of stage, discharge, and water quality of streams, stage and contents in lakes and reservoirs, and water levels and water quality in wells. Volume 3 contains discharge records for 187 gaging stations, stage and contents for 48 lakes and reservoirs,