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1

Compliant Walker  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

2

Compliant walker  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

3

Dandy-Walker Syndrome  

MedlinePLUS

NINDS Dandy-Walker Syndrome Information Page Table of Contents (click to jump to sections) What is Dandy-Walker Syndrome? Is there ... being done? Clinical Trials Organizations What is Dandy-Walker Syndrome? Dandy-Walker Syndrome is a congenital brain ...

4

Walker's Eleodes (Coleoptera: Tenebrionidae).  

PubMed

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

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

2014-01-01

5

Walker groups Fred Richman  

E-print Network

Walker groups Fred Richman Florida Atlantic University Boca Raton, Florida 33431 Abstract A reformulation of Walker's theorem on the cancellation of Z says that any two homomorphisms from an abelian group. In this paper we give a constructive proof of Walker's theorem for B a direct sum, over any discrete index set

Richman, Fred

6

Carol Walker Assistant Vice President  

E-print Network

Carol Walker Assistant Vice President UF Planning, Design & Construction Eugene Herring Director Kathleen Wood Executive Secretary/HR Coordinator Dan Walker Contracts Administrator Billy Triay Sr Property

Slatton, Clint

7

Intelligent Robotic Walker Design  

Microsoft Academic Search

This paper aims to present the current development of an intelligent robotic walker. This machine is designed as a walking aid for the visually impaired. The machine is equipped with different sensors to navigate its motion in the indoor environment such as hospitals, hotels, airports, and museums. The user drives the walker while the two front wheels have the ability

W. GHARIEB

2006-01-01

8

E. L. Walker Curriculum vitae, page 1 ELSBETH L. WALKER  

E-print Network

E. L. Walker Curriculum vitae, page 1 ELSBETH L. WALKER University of Massachusetts Dept. L. Walker Curriculum vitae, page 2 1984: Phi Beta Kappa Funded Grants: 2012: NSF DUE#1140805 Approaches to Understanding Global Regulation in Paclitaxel Accumulation." S. Roberts, PI and E. L. Walker

9

November 18, 2004 Mark Walker  

E-print Network

1 November 18, 2004 Mark Walker Director of Public Affairs Northwest Power & Conservation Council Dear Mr. Walker, We are pleased to provide a few short comments on the Council's Draft Fifth Power Plan

10

April 23, 2004 Mark Walker  

E-print Network

April 23, 2004 Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851 SW Administration � Doc. 2004-02 Dear Mr. Walker, Springfield Utility Board ("SUB") appreciates this opportunity

11

December 12, 2003 Mark Walker  

E-print Network

December 12, 2003 Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851 Administration � Doc. 2003-18 Dear Mr. Walker, Springfield Utility Board ("SUB") appreciates this opportunity

12

July 13, 2007 Mark Walker  

E-print Network

July 13, 2007 Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851 SW at the Northwest Power and Conservation Planning Assumptions, Council Document 2007-7 Dear Mr. Walker: On behalf

13

November 2012 ROBERT T. WALKER  

E-print Network

1 November 2012 ROBERT T. WALKER Department of Geography, Michigan State University 116 Geography Refereed Journal Articles Walker, R., Arima, E., Messina, J., Soares-Filho, B., Perz, S., Sales, M, P., Myers, R. J., Swinton, S. M., and Walker. R. 2012. Exchange rates, soybean supply response

Walker, Robert T.

14

Thad G. Walker Research Highlights  

E-print Network

Thad G. Walker Research Highlights LASER TRAPPING AND COOLING OF ATOMS Laser cooling methods have processing. Some of the contributions of Prof. Walker and his group are: · First diode-laser atom trap, light. Walker Publications in Refereed Journals 27 Physical Review Letters, Nature Physics 2 Reviews of Modern

Yavuz, Deniz

15

October 5, 2006 Mark Walker  

E-print Network

October 5, 2006 Mark Walker Director of Public Affairs Northwest Power & Conservation Council 851@nwcouncil.org Dear Mr. Walker; I am writing to express disappointment with the recent recommendation by the Northwest of Zoo visitors. Since 2005, the Zoo's marketing and development offices #12;Mark Walker Page Two worked

16

Howie Choset Sean Walker  

E-print Network

Howie Choset Sean Walker Kunnayut Eiamsa-Ard Carnegie Mellon University Scaife Hall Pittsburgh of unknown environments. Recall that a roadmap is a ge- ometric structure that a robot uses to plan a path between two points in an environment. If the robot knows the roadmap, then it knows the environment

LaValle, Steven M.

17

Vicious walkers, friendly walkers and Young tableaux III: Between two walls  

E-print Network

Vicious walkers, friendly walkers and Young tableaux III: Between two. Running Head: Vicious walkers between two walls. November 18, 2002 configurations of vicious walkers confined to lie between two impenetrable* * walls, as well

Krattenthaler, Christian

18

Dissimilar bouncy walkers  

E-print Network

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

Michael A Lomholt; Ludvig Lizana; Tobias Ambjornsson

2010-11-25

19

Genetics Home Reference: Dandy-Walker syndrome  

MedlinePLUS

... Research studies OMIM Genetic disorder catalog Conditions > Dandy-Walker syndrome On this page: Description Genetic changes Inheritance ... Glossary definitions Reviewed July 2012 What is Dandy-Walker syndrome? Dandy-Walker syndrome is a condition that ...

20

21 CFR 890.3825 - Mechanical walker.  

...2014-04-01 2014-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food...Prosthetic Devices 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged device with a...

2014-04-01

21

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food...Prosthetic Devices 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged device with a...

2013-04-01

22

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food...Prosthetic Devices 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged device with a...

2011-04-01

23

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food...Prosthetic Devices 890.3825 Mechanical walker. (a) Identification. A mechanical walker is a four-legged device with a...

2012-04-01

24

Synthetic molecular walkers.  

PubMed

In biological systems, molecular motors have been developed to harness Brownian motion and perform specific tasks. Among the cytoskeletal motor proteins, kinesins ensure directional transport of cargoes to the periphery of the cell by taking discrete steps along microtubular tracks. In the past decade there has been an increasing interest in the development of molecules that mimic aspects of the dynamics of biological systems and can became a starting point for the creation of artificial transport systems.To date, both DNA-based and small-molecule walkers have been developed, each taking advantage of the different chemistries available to them. DNA strollers exploit orthogonal base pairing and utilize strand-displacement reactions to control the relative association of the component parts. Small-molecule walkers take advantage of the reversibility of weak noncovalent interactions as well as the robustness of dynamic covalent bonds in order to transport molecular fragments along surfaces and molecular tracks using both diffusional processes and ratchet mechanisms. Here we review both types of synthetic systems, including their designs, dynamics, and how they are being used to perform functions by controlled mechanical motion at the molecular level. PMID:24770565

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

2014-01-01

25

Asymmetric passive dynamic walker.  

PubMed

The objective of this research is to better understand the dynamics of gait asymmetry in humans with central nervous system damage, such as stroke, by using a model of a passive dynamic walker (PDW). By changing the mass, mass location, knee location, and leg length of one leg while leaving the parameters of the other leg unchanged, we show that stable asymmetric walking patterns exist for PDW models. The asymmetric PDW model shows several stable walking patterns that have a single, double, and quadruple repeat pattern where the step lengths between the two legs differ by over 15%. This model will allow an analysis of the passive dynamics of walking separate from the cognitive control in asymmetric human walking to test different gait rehabilitation hypotheses. PMID:22275663

Honeycutt, Craig; Sushko, John; Reed, Kyle B

2011-01-01

26

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

27

A Smart Walker to Understand Walking Abilities  

E-print Network

1 A Smart Walker to Understand Walking Abilities Pascal Poupart Associate Professor Cheriton School · Smart Walker · User study at the Village of Winston Park · Behaviour recognition · Limb tracking #12? Pascal Poupart, 11/21/2008 #12;7 Smart Walker walker devices + caregivers users Force sensors Load

Poupart, Pascal

28

Walker-Breaker games Lisa Espig  

E-print Network

Walker-Breaker games Lisa Espig Alan Frieze Michael Krivelevich Wesley Pegden§ May 7, 2014 Abstract We introduce and analyze the Walker-Breaker game, a variant of Maker-Breaker games where Maker the following variant on the standard Maker-Breaker game. In this variant, the Walker-Breaker game, the "Walker

Frieze, Alan

29

Richard C. Ferrero William A. Walker  

E-print Network

Richard C. Ferrero William A. Walker National Marine Mammal laboratory. Alaska Fisheries ScienceI., 1985; Perryman and Lynn, 1993; Heyning and Perrin, 1994; Walker and Cowan1; Walker et a1.2). Two flipper bone development and summarized 1 Walker, W. A., and D. F. Cowan. 19

30

Simple autonomous Mars walker  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

31

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

32

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

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

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

33

16 CFR 1216.2 - Requirements for infant walkers.  

...2014-01-01 false Requirements for infant walkers. 1216.2 Section 1216.2 Commercial...ACT REGULATIONS SAFETY STANDARD FOR INFANT WALKERS 1216.2 Requirements for infant walkers. Each infant walker shall comply...

2014-01-01

34

April 21, 2004 Mr. Mark Walker  

E-print Network

April 21, 2004 Mr. Mark Walker Director of Public Affairs Northwest Power Planning Council 851 S.W. Sixth Avenue, Suite 1100 Portland, OR 97204-1348 Dear Mr. Walker: I am writing to comment on Document

35

Mark Walker Director of Public Affairs  

E-print Network

1 Mark Walker Director of Public Affairs Northwest Power and Conservation Council 851 SW 6th Avenue, Suite 1100 Portland, OR 97204 Mr. Walker: Please accept these comments from Emerald People's Utility

36

Type-2 Fuzzy Sets and Bichains John Harding, Carol Walker and Elbert Walker  

E-print Network

Type-2 Fuzzy Sets and Bichains John Harding, Carol Walker and Elbert Walker Abstract This paper-mail: jharding@nmsu.edu Carol Walker New Mexico State University, Las Cruces NM 88003, e-mail: hardy@nmsu.edu Elbert Walker New Mexico State University, Las Cruces NM 88003, e-mail: elbert@nmsu.edu 1 #12;2 John

Harding, John

37

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

E-print Network

VICIOUS WALKERS, FRIENDLY WALKERS AND YOUNG TABLEAUX II: WITH A WALL CHRISTIAN KRATTENTHALERx and watermelon configu­ rations of vicious walkers in the presence of an impenetrable wall by showing functions. For the problem of n­friendly walkers, we derive exact asymptotics for the number of stars

Krattenthaler, Christian

38

Vicious walkers, friendly walkers and Young tableaux III: Between two walls  

E-print Network

Vicious walkers, friendly walkers and Young tableaux III: Between two walls Christian Krattenthaler Cedex, France. Running Head: Vicious walkers between two walls. November 18, 2002 #3; Research partially;gurations of vicious walkers con#12;ned to lie between two impenetrable walls, as well as corresponding

Krattenthaler, Christian

39

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

E-print Network

VICIOUS WALKERS, FRIENDLY WALKERS AND YOUNG TABLEAUX II: WITH A WALL walkers in the presence of an impenetrable wall by sho* *wing that these follow from standard. For the problem of n-friendly walker* *s, we derive exact asymptotics for the number of stars

Krattenthaler, Christian

40

Pacific Hadley and Walker Circulation 239 THE PACIFIC SECTOR HADLEY AND WALKER  

E-print Network

Pacific Hadley and Walker Circulation 239 239 Chapter 8 THE PACIFIC SECTOR HADLEY AND WALKER variation is associated with varia- tions in the Walker circulation; e.g., El Niño/Southern Oscillation et al., this volume; and Chapter 5, "Interannual to Interdecadal Variations of the Hadley and Walker

41

Two quantum walkers sharing coins  

E-print Network

We consider two independent quantum walks on separate lines augmented by partial or full swapping of coins after each step. For classical random walks, swapping or not swapping coins makes little difference to the random walk characteristics, but we show that quantum walks with partial swapping of coins have complicated yet elegant inter-walker correlations. Specifically we study the joint position distribution of the reduced two-walker state after tracing out the coins and analyze total, classical and quantum correlations in terms of the mutual information, the quantum mutual information, and the measurement-induced disturbance. Our analysis shows intriguing quantum features without classical analogues.

Peng Xue; Barry C. Sanders

2011-12-07

42

WALKER REPORTING SERVICE (724) 224-5282  

E-print Network

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 - - - - WALKER REPORTING SERVICE WALKER WALKER REPORTING SERVICE 2500 HOWES RUN ROAD TARENTUM, PA 15084 #12;1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 - - - - WALKER REPORTING SERVICE (724) 224-5282 2 P-R

US Army Corps of Engineers

43

Publications in Refereed Journals Thad G. Walker  

E-print Network

Publications in Refereed Journals Thad G. Walker Professor of Physics University of Wisconsin­Madison 1. J. Huennekens, Z. Wu, and T. G. Walker, "Ionization, excitation of high-lying atomic states, T. G. Walker, and W. Happer, "Spin-Rotation Interaction of Noble-Gas Alkali-Metal Atom Pairs," Phys

Saffman, Mark

44

Name: Walker White Title: Research Associate  

E-print Network

Name: Walker White Title: Research Associate Office: Phone: (607)255-2969 Email: wmwhite Cao, Benjamin Sowell, Alan Demers, Johannes Gehrke, Christoph Koch, and Walker White, An Evaluation Databases (VLDB 2009). · Walker White, Christoph Koch, Johannes Gehrke, and Alan Demers Better Scripts

Keinan, Alon

45

Walker's theorem without coordinates Andrzej Derdzinskia  

E-print Network

Walker's theorem without coordinates Andrzej Derdzinskia Department of Mathematics, The Ohio State classification, due to Walker Q. J. Math. 1, 69 1950 , of null parallel distributions on pseudo of coordinates in the usual formulation of Walker's theorem. © 2006 American Institute of Physics. DOI: 10

Derdzinski, Andrzej

46

Doreen Walker Compiled by Alan Doyle (2002)  

E-print Network

Doreen Walker fonds Compiled by Alan Doyle (2002) University of British Columbia Archives #12;Table catalogue) #12;Fonds Description Doreen Walker fonds. ­ 1660-1990 [predominant 1920-1985]. 1.2 m of textual records. 90 photographs. Biographical Sketch Doreen Elizabeth Walker was born in Vancouver in 1920. She

Handy, Todd C.

47

ZERO DYNAMICS OF UNDERACTUATED PLANAR BIPED WALKERS  

E-print Network

ZERO DYNAMICS OF UNDERACTUATED PLANAR BIPED WALKERS E.R. Westervelt 1 J.W. Grizzle 1 D of the zero dynamics correspond to asymptotically stabilizable orbits of the full hybrid model of the walker A planar biped walker is a robot that locomotes via alternation of two legs in the sagittal plane (see

Grizzle, Jessy W.

48

Configuration of Autonomous Walkers for Extreme Terrain  

Microsoft Academic Search

Robots that can competently, efficiently, and autonomously operate in extreme terrain do not exist. Although walking locomotion offers unique advantages, existing walking mech anisms are not suited to the comprehensive requirements of extreme terrain autonomy. This work synthesizes and ana lyzes candidate walker configurations, implements and tests a walker of unprecedented capability and design, and devel ops insights regarding walker

John E. Bares; William L. Whittaker

1993-01-01

49

Bruce N. Walker RICE UNIVERSITY  

E-print Network

Copyright Bruce N. Walker 2000 #12;RICE UNIVERSITY Magnitude Estimation of Conceptual Data OF THE REQUIREMENTS FOR THE DEGREE Doctor of Philosophy APPROVED, THESIS COMMITTEE: David M. Lane, Associate Professor like to acknowledge the contribution of my advisor, David M. Lane, who granted me the freedom

50

Hemispherical Scale (Saissetia coffeae (Walker))  

Microsoft Academic Search

emispherical or helmet scale (Saissetia coffeae (Walker) (Homoptera: Coccidae)) is a yellow-brown to dark brown scale found on leaves, on small twigs, shoots, and fruits. The scale is shaped like a half-sphere, being very dome-shaped with the base varying from circular to elongated. It is between 1.5 and 3 millimeters (mm) long when mature. Up to 600 eggs are laid

Donald Nafus

51

Motion Control of Passive Intelligent Walker Using Servo Brakes  

Microsoft Academic Search

We propose a new intelligent walker based on passive robotics that assists the elderly, handicapped people, and the blind who have difficulty in walking. We developed a prototype of the robot technology walker (RT walker), a passive intelligent walker that uses servo brakes. The RT walker consists of a support frame, two casters, two wheels equipped with servo brakes, and

Yasuhisa Hirata; Asami Hara; Kazuhiro Kosuge

2007-01-01

52

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

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

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

53

75 FR 51178 - Safety Standard for Infant Walkers; Correction  

Federal Register 2010, 2011, 2012, 2013

...CFR Part 1216 Safety Standard for Infant Walkers; Correction AGENCY: Consumer Product...document established a standard for infant walkers. The Commission is correcting a typographical...provision concerning warning statements on walkers with parking brakes. DATES:...

2010-08-19

54

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

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

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

55

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

Federal Register 2010, 2011, 2012, 2013

...Establishment of Class E Airspace; Walker, MN AGENCY: Federal Aviation Administration...establishes Class E airspace at Walker, MN. Controlled airspace is necessary to accommodate...establish Class E airspace for the Walker, MN, area, creating controlled airspace...

2013-08-08

56

Walker Branch Watershed Ecosystems Data  

DOE Data Explorer

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

57

________________________________________________________________________The MIND Institute__________________ Cheryl K. Walker, MD  

E-print Network

, Dr. Walker is trying to understand how the gestational environment responds to maternal conditions and developmental disabilities for the past several years. Dr. Walker's early research concentrated on the impact these alterations have for neurodevelopment. Publications (selected, relevant to autism) Zerbo O, Iosif AM, Delwiche

Nguyen, Danh

58

A Robotic Walker that Provides Guidance  

Microsoft Academic Search

This paper describes a robotic walker, designed as an assist ive device for cognitively frail elderly people. Locomotion is most often the primary form of exercise for the elderly. Devices t hat provide mobility assistance are critical for the health and well being of such individuals. Previous work on walkers focused primarily on safety but offered little or no assistance

Aaron Morris; Raghavendra Donamukkala; Anuj Kapuria; Aaron Steinfeld; Judith T. Matthews; Jacqueline Dunbar-jacobs; Sebastian Thrun

2003-01-01

59

A Robotic Walker That Provides Guidance  

Microsoft Academic Search

This paper describes a robotic walker designed as an assistive device for frail elderly people with cognitive impairment. Lo- comotion is most often the primary form of exercise for the elderly, and devices that provide mobility assistance are criti- cal for the health and well being of such individuals. Previous work on walkers focused primarily on safety but offered little

Aaron Morris; Raghavendra Donamukkala; Anuj Kapuria; Aaron Steinfeld; Judith T. Matthews; Jacqueline Dunbar-Jacob; Sebastian Thrun

2002-01-01

60

From Vicious Walkers to TASEP  

E-print Network

We propose a model of semi-vicious walkers, which interpolates between the totally asymmetric simple exclusion process and the vicious walkers model, having the two as limiting cases. For this model we calculate the asymptotics of the survival probability for $m$ particles and obtain a scaling function, which describes the transition from one limiting case to another. Then, we use a fluctuation-dissipation relation allowing us to reinterpret the result as the particle current generating function in the totally asymmetric simple exclusion process. Thus we obtain the particle current distribution asymptotically in the large time limit as the number of particles is fixed. The results apply to the large deviation scale as well as to the diffusive scale. In the latter we obtain a new universal distribution, which has a skew non-Gaussian form. For $m$ particles its asymptotic behavior is shown to be $e^{-\\frac{y^{2}}{2m^{2}}}$ as $y\\to -\\infty $ and $e^{-\\frac{y^{2}}{2m}}y^{-\\frac{m(m-1)}{2}}$ as $y\\to \\infty $.

T. C. Dorlas; A. M. Povolotsky; V. B. Priezzhev

2008-12-01

61

Averaging Robertson-Walker cosmologies  

SciTech Connect

The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy, strictly speaking any cosmological model should be recovered from such a procedure. We apply the scalar spatial averaging formalism for the first time to linear Robertson-Walker universes containing matter, radiation and dark energy. The formalism employed is general and incorporates systems of multiple fluids with ease, allowing us to consider quantitatively the universe from deep radiation domination up to the present day in a natural, unified manner. Employing modified Boltzmann codes we evaluate numerically the discrepancies between the assumed and the averaged behaviour arising from the quadratic terms, finding the largest deviations for an Einstein-de Sitter universe, increasing rapidly with Hubble rate to a 0.01% effect for h = 0.701. For the {Lambda}CDM concordance model, the backreaction is of the order of {Omega}{sub eff}{sup 0} Almost-Equal-To 4 Multiplication-Sign 10{sup -6}, with those for dark energy models being within a factor of two or three. The impacts at recombination are of the order of 10{sup -8} and those in deep radiation domination asymptote to a constant value. While the effective equations of state of the backreactions in Einstein-de Sitter, concordance and quintessence models are generally dust-like, a backreaction with an equation of state w{sub eff} < -1/3 can be found for strongly phantom models.

Brown, Iain A.; Robbers, Georg [Institut fuer Theoretische Physik, Philosophenweg 16, 69120 Heidelberg (Germany)] [Institut fuer Theoretische Physik, Philosophenweg 16, 69120 Heidelberg (Germany); Behrend, Juliane, E-mail: I.Brown@thphys.uni-heidelberg.de, E-mail: G.Robbers@thphys.uni-heidelberg.de, E-mail: Juliane.Behrend@uni-ulm.de [Institut fuer Theoretische Physik, Albert-Einstein-Allee 11, 89069 Ulm (Germany)] [Institut fuer Theoretische Physik, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

2009-04-15

62

Department of Mechanical Engineering Spring 2012 Motorized Rolling Walker  

E-print Network

PENNSTATE Department of Mechanical Engineering Spring 2012 Motorized Rolling Walker Overview Mr using a conventional walker which hinders his rehabilitation process. A motorized walker would provide Integrated a user-friendly throttle and control system to operate the walker Analysis Performed finite

Demirel, Melik C.

63

Collision avoidance between two walkers: role-dependent strategies  

E-print Network

1 Collision avoidance between two walkers: role- dependent strategies Anne-Hélène Olivier1 been previously demonstrated that walkers are able to anticipate the risk of future collision walker in the task of controlling MPD. A specific question was: does the walker giving way (2nd

Paris-Sud XI, Université de

64

A Robotically-Augmented Walker for Older Adults  

Microsoft Academic Search

Many older adults use walkers to improve their stability and safety while walking. We have developed a robotically augmented walker to reduce fall risk and confusion, and to increase walker convenience and enjoyment. Using a modified version of the CARMEN navigation software suite (11), the walker is capable of parking itself and returning to the user when signaled by remote

Jared Glover; David Holstius; Michael Manojlovich; Keirsten Montgomery; Aaron Powers; Jack Wu; Sara Kiesler; Judith Matthews; Sebastian Thrun

65

Exploration and Trapping of Mortal Random Walkers  

E-print Network

Exploration and trapping properties of random walkers that may evanesce at any time as they walk have seen very little treatment in the literature, and yet a finite lifetime is a frequent occurrence, and its effects on a number of random walk properties may be profound. For instance, whereas the average number of distinct sites visited by an immortal walker grows with time without bound, that of a mortal walker may, depending on dimensionality and rate of evanescence, remain finite or keep growing with the passage of time. This number can in turn be used to calculate other classic quantities such as the survival probability of a target surrounded by diffusing traps. If the traps are immortal, the survival probability will vanish with increasing time. However, if the traps are evanescent, the target may be spared a certain death. We analytically calculate a number of basic and broadly used quantities for evanescent random walkers.

S. B. Yuste; E. Abad; Katja Lindenberg

2013-04-28

66

CONSTITUENTS OF PROPOLIS Penelope WALKER Eva CRANE  

E-print Network

CONSTITUENTS OF PROPOLIS Penelope WALKER Eva CRANE Woodside House, Woodside Hill, Gerrards Cross) a complete list of compounds so far identified in propolis. Of these, (a) will be dealt with elsewhere (CRANE

Paris-Sud XI, Université de

67

Misconceptions in Halliday, Resnick and Walker's textbook  

E-print Network

Eleven misconceptions involving Relativity, Gravitation and Cosmology are exposed, that appeared in the textbook: Fundamentals of Physics, 7th Edition, by Halliday, Resnick and Walker, Willey, New York (2005), or other companion textbooks.

Berman, M S

2005-01-01

68

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

Federal Register 2010, 2011, 2012, 2013

...Establishment of Class E Airspace; Walker, MN AGENCY: Federal Aviation Administration...to establish Class E airspace at Walker, MN. Controlled airspace is necessary to accommodate...procedures at Walker Municipal Airport, Walker, MN. Controlled airspace is needed for...

2013-04-30

69

Vicious random walkers in the limit of a large number of walkers  

SciTech Connect

The vicious random walker problem on a line is studied in the limit of a large number of walkers. The multidimensional integral representing the probability that the p walkers will survive a time t (denoted P{sub t}{sup (p)}) is shown to be analogous to the partition function of a particular one-component Coulomb gas. By assuming the existence of the thermodynamic limit for the Coulomb gas, one can deduce asymptotic formulas for P{sub t}{sup (p)} in the large-p, large-t limit. A straightforward analysis gives rigorous asymptotic formulas for the probability that after a time t the walkers are in their initial configuration (this event is termed a reunion). Consequently, asymptotic formulas for the conditional probability of a reunion, given that all walkers survive, are derived. Also, an asymptotic formula for the conditional probability density that any walker will arrive at a particular point in time t, given that all p walkers survive, is calculated in the limit t >> p.

Forrester, P.J. (La Trobe Univ., Bundoora, Victoria (Australia))

1989-09-01

70

Hydrodynamical random walker with chemotactic memory  

E-print Network

A three-dimensional hydrodynamical model for a micro random walker is combined with the idea of chemotactic signaling network of E. coli. Diffusion exponents, orientational correlation functions and their dependence on the geometrical and dynamical parameters of the system are analyzed numerically. Because of the chemotactic memory, the walker shows superdiffusing displacements in all directions with the largest diffusion exponent for a direction along the food gradient. Mean square displacements and orientational correlation functions show that the chemotactic memory washes out all the signatures due to the geometrical asymmetry of the walker and statistical properties are asymmetric only with respect to the direction of food gradient. For different values of the memory time, the Chemotactic index (CI) is also calculated.

H. Mohammady; B. Esckandariun; A. Najafi

2014-10-01

71

Hydrodynamical random walker with chemotactic memory  

E-print Network

A three-dimensional hydrodynamical model for a micro random walker is combined with the idea of chemotactic signaling network of E. coli. Diffusion exponents, orientational correlation functions and their dependence on the geometrical and dynamical parameters of the system are analyzed numerically. Because of the chemotactic memory, the walker shows superdiffusing displacements in all directions with the largest diffusion exponent for a direction along the food gradient. Mean square displacements and orientational correlation functions show that the chemotactic memory washes out all the signatures due to the geometrical asymmetry of the walker and statistical properties are asymmetric only with respect to the direction of food gradient. For different values of the memory time, the Chemotactic index (CI) is also calculated.

Mohammady, H; Najafi, A

2014-01-01

72

Dual position locking joint design for a medical walker  

E-print Network

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

Beecher, Eric M

2010-01-01

73

5. VIEW LOOKING WEST ON WALKER STREET SHOWING CHURCH AND ...  

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

5. VIEW LOOKING WEST ON WALKER STREET SHOWING CHURCH AND HOUSE FRONTING WALKER STREET AND CHURCH AND HOUSE FRONTING ON WEST BOUNDARY STREET - Frogtown District, Bounded by Jones, I-66 Ramp, & West Boundary Streets, Savannah, Chatham County, GA

74

EINLADUNG ZUM KOLLOQUIUM Prof. Mark Walker, Ph.D.  

E-print Network

( EINLADUNG ZUM KOLLOQUIUM Prof. Mark Walker, Ph.D. (Schenectady/USA, z.Zt. Berlin) War der Jahrhundert ausgelöst hat. Mark Walker ist John Bigelow Professor of History am Department of History, Union

Bongartz, Klaus

75

[U.S. Fish and Wildlife Service letterhead] Mark Walker  

E-print Network

[U.S. Fish and Wildlife Service letterhead] Mark Walker Director, Public Affairs Division Northwest Power Planning Council 851 SW Sixth Avenue, Suite 1100 Portland, Oregon 97204 Dear Mr. Walker: The Fish

76

Department of Mechanical Engineering Spring 2013 Intelligent Walker for Retirees  

E-print Network

PENNSTATE Department of Mechanical Engineering Spring 2013 Intelligent Walker for Retirees Overview For this project TPC Innovation and Design was interested in improving an existing assistive walker they had

Demirel, Melik C.

77

Dynamical Backreaction in Robertson-Walker Spacetime  

E-print Network

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

Benjamin Eltzner; Hanno Gottschalk

2010-03-18

78

Motion control algorithms for a new intelligent robotic walker in emulating ambulatory device function  

Microsoft Academic Search

This paper propose a new motion control algorithms for an intelligent robotic walker that emulate ambulatory device function such as cane, wheeled walker, and standard walker. Usually, the objective in designing robotic walker is to replaced conventional wheeled walker and introduce new high level functions such as guidance, health monitoring, and others. We extend the objective of a robotic walker

Jr. O. Chuy; Y. Hirata; Zhidong Wang; K. Kosuge

2005-01-01

79

The Betten-Walker spread and Cayley's ruled cubic surface  

E-print Network

The Betten-Walker spread and Cayley's ruled cubic surface Hans Havlicek Rolf Riesinger Unserem) spread which is also a dual (maximal partial) spread. It is precisely the Betten-Walker spreads that allow for this construction. Every infinite Betten-Walker spread is not an algebraic set of lines

Havlicek, Hans

80

Smart Walkers! Enhancing the Mobility of the Elderly (Extended Abstract)  

E-print Network

Smart Walkers! Enhancing the Mobility of the Elderly (Extended Abstract) Mathieu Sinn David R, Canada N2L 3G1 ppoupart@cs.uwaterloo.ca ABSTRACT The idea of Smart Walkers is to equip customary rolling walkers with sensors in order to assist users, caregivers and clinicians. The integral part of the Smart

Poupart, Pascal

81

A Robotic Walker That Provides Guidance Aaron Morris  

E-print Network

A Robotic Walker That Provides Guidance Aaron Morris� , Raghavendra Donamukkala� , Anuj Kapuria Pittsburgh, PA Abstract This paper describes a robotic walker designed as an assistive device for frail of such individuals. Previous work on walkers focused primarily on safety but offered little or no assistance

Thrun, Sebastian

82

DNA walker circuits: computational potential, design, and verification  

E-print Network

DNA walker circuits: computational potential, design, and verification Frits Dannenberg1 , Marta in DNA `walker' systems which were recently shown to be capable of navigating a programmable track Boolean functions. DNA walkers, like DSDs, are also susceptible to errors. We develop a discrete

Oxford, University of

83

STS-30 Commander Walker on forward flight deck  

NASA Technical Reports Server (NTRS)

On Atlantis', Orbiter Vehicle (OV) 104's, forward flight deck between commanders and pilots seats, STS-30 Commander David M. Walker smiles while having his picture taken. Walker, wearing a mission polo shirt and light blue flight coverall pants, holds onto the commanders seat back. Forward flight control panels are visible above Walker's head and behind him.

1989-01-01

84

Broadening the Applicability of Relational Learning Trevor Walker  

E-print Network

Computer Sciences Department Broadening the Applicability of Relational Learning Trevor Walker Walker A Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Computer Sciences) At the UNIVERSITY OF WISCONSIN-MADISON 2011 #12;© Copyright by Trevor Walker

Shavlik, Jude W.

85

Department of Bioengineering Spring 2011 Self-Propelled Walker  

E-print Network

PENNSTATE Department of Bioengineering Spring 2011 Self-Propelled Walker Overview Based on the user's experience on the previous model, a tricycle arrangement motorized walker, several areas of the design needed The main goal of creating a walker is to decrease the strength required, and enable the user to travel

Demirel, Melik C.

86

DNA walker circuits: computational potential, design, and verification  

E-print Network

DNA walker circuits: computational potential, design, and verification Frits Dannenberg1 , Marta- calised reactions occur in DNA `walker' systems which were recently shown to be capable of navigating for evaluating Boolean functions. DNA walkers, like DSDs, are also susceptible to errors. We develop a discrete

Oxford, University of

87

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

88

Scaling Games to Epic Proportions Walker White  

E-print Network

Scaling Games to Epic Proportions Walker White Cornell University Ithaca, NY 14853, USA wmwhite@cs.cornell.edu ABSTRACT We introduce scalability for computer games as the next frontier for techniques from data management. A very important aspect of computer games is the artificial intelligence (AI) of non

Keinan, Alon

89

by John Walker The Hacker's Diet  

E-print Network

: managing, fixing, and solving 15 What, me exercise? 19 3 THE RUBBER BAG 21 What goes in 22 What you burn 22 and motivation 103 Details 107 II Management 111 7 WEIGHT MONITORING 113 Getting started 113 Every day 115 Everyby John Walker #12; The Hacker's Diet How to lose weight and hair through stress and poor nutrition

Bernstein, Daniel

90

Some general new Einstein Walker manifolds  

E-print Network

In this paper, Lie symmetry group method is applied to find the lie point symmetries group of a PDE system that is determined general form of four-dimensional Einstein Walker manifold. Also we will construct the optimal system of one-dimensional Lie subalgebras and investigate some of its group invariant solutions.

Mehdi Nadjafikhah; Mehdi Jafari

2012-06-17

91

Nonassociative geometry: Friedmann-Robertson-Walker spacetime  

E-print Network

In (Phys. Rev. D 62, 081501, 2000) we proposed a unified approach to description of continuous and discrete spacetime based on nonassociative geometry and described nonassociative smooth and discrete de Sitter models. In our paper we give the description of nonassociative Friedmann-Robertson-Walker spacetime.

Alexander I. Nesterov; Lev V. Sabinin

2004-06-24

92

undergraduate programs walker college of business  

E-print Network

University Nestled in the Blue Ridge Mountains of North Carolina, Appalachian State University offers business environment demands dynamic leaders. The Walker College of Business at Appalachian State's enthusiasm for and impact on Appalachian State University, its students and alumni. Appalachian State

Thaxton, Christopher S.

93

Infant walker use, injuries, and motor development  

Microsoft Academic Search

OBJECTIVES: To study the impact of infant walker use on motor development and injuries. POPULATION: One hundred and eighty five parents or primary care givers who attended a Singapore government polyclinic from September 1993 to February 1994, with their infants between 7 to 10 months, for a developmental assessment session. SETTING: A government polyclinic in Singapore. METHODS: The parent or

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

1997-01-01

94

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

95

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.

96

In the StarWalker virtual environment,  

E-print Network

In the StarWalker virtual environment, users explore a shared semantic space and collaborate in linguistics, sociology, and anthropology. For example, linguists talk about contextualization cues, which's communicative intentions and goals. In sociology, frame analysis focuses on the perception and interpretation

Chen, Chaomei

97

JOHN A. WALKER COLLEGE OF BUSINESS  

E-print Network

JOHN A. WALKER COLLEGE OF BUSINESS COMPUTER INFORMATION SYSTEMS MINOR (310) Fall 2011 ­ Summer 2012 Students not majoring in the College of Business may earn a computer information systems minor not admitted to the College of Business may take at most five business courses at the 3000 or 4000 level

Thaxton, Christopher S.

98

Walker of Time [and Teacher's Guide].  

ERIC Educational Resources Information Center

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

Vick, Helen Hughes

99

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

100

New technical advances in swivel walkers.  

PubMed

Swivel walkers were commonly prescribed for children with complete thoracic lesion myelomeningocele in the 1970s and 80s, when the incidence of spina bifida in the UK was of the order of 3 per 100,000 live births. The advent of reciprocal walking orthoses provided a more suitable alternative for those with good upper limb and trunk function, and swivel walkers were then used primarily for very young or more severely disabled patients. Pre-natal screening has dramatically reduced the incidence of spina bifida in the UK and subsequently swivel walkers have been used in a wider range of pathology, including spinal muscular atrophy, multiple sclerosis, muscular dystrophy and other neurological conditions that lead to lower limb dysfunction. The detail design of these devices has been adapted to accommodate the specific problems encountered in these conditions. In particular the designs have been updated to: enable very young patients to be more readily fitted at the age of 1 year; allow the walking mechanisms to be conveniently adjusted for easier ambulation when weakness or lack of confidence inhibits performance; permit simple adjustment to a standing frame mode to enhance stability in situations of increased risk; promote manual handling practice that is compatible with the National Health Service (NHS) policy of compliance with relevant regulations. To underpin appropriate prescription and safe supply the NHS Procurement Agency have encouraged the development of a common course for all types of swivel walker. PMID:14571943

Stallard, J; Lomas, B; Woollam, P; Farmer, I R; Jones, N; Poiner, R; Miller, K

2003-08-01

101

Empirical Studies in Discourse Marilyn A. Walker  

E-print Network

and interpretation. Section 2 gives a general overview of empirical studies in discourse and describes an empiricalEmpirical Studies in Discourse Marilyn A. Walker & Johanna D. Moore ¡ 1. Introduction this approachledtomanytheoreticaladvances,modelsdevelopedinthismanneraredifficult to evaluate because it is hard to tell whether

Moore, Johanna D.

102

A robotic walker with standing assistance  

Microsoft Academic Search

This paper proposes a walker system with power assistance device for standing up motion. Our system focuses on family use for aged person who needs nursing in their daily life. Our key ideas are two topics. The first topic is new assistance manipulator mechanism with four parallel linkages. Our proposed manipulator mechanism requires only smaller actuators and realizes rigid structure

Daisuke Chugo; Wataru Matsuoka; Songmin Jia; Kunikatsu Takase

2008-01-01

103

Clinical evaluation of Guido robotic walker  

Microsoft Academic Search

The Guido is a robotic walker that provides naviga- tion and obstacle-avoidance assistance. Engineering tests have found that the device performs adequately and presents no haz- ard to the user. The performance of the Guido was compared with a low-tech mobility aid, the Assistive Mobility Device (AMD) developed at the Atlanta Department of Veterans Affairs Medical Center, in trials involving

Andrew J. Rentschler; Richard Simpson; Rory A. Cooper; Michael L. Boninger

2008-01-01

104

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

E-print Network

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

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

2000-06-23

105

Modern lacustrine stromatolites, Walker Lake, Nevada  

NASA Astrophysics Data System (ADS)

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

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

1982-05-01

106

``Good-Walker'' + QCD dipoles = Hard Diffraction  

E-print Network

The Good-Walker mechanism for diffraction is shown to provide a link between total and diffractive structure functions and to be relevant for QCD calculations at small x_{Bj}. For Deep-Inelastic scattering on a small-size target (cf. an onium) the r\\^ ole of Good-Walker ``diffractive eigenstates'' is played by the QCD dipoles appearing in the $1/N_C$ limit of QCD. Hard diffraction is thus related to the QCD tripe-dipole vertex which has been recently identified (and calculated) as being a conformal invariant correlator and/or a closed-string amplitude. An extension to hard diffraction at HERA via $k_T-$factorisation of the proton vertices leads to interesting phenomenology.

R. Peschanski

1998-05-14

107

Brownian walkers within subdiffusing territorial boundaries  

E-print Network

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 non-monotonicity in the time dependence of the MSD, giving rise to transient negative diffusion.

Luca Giuggioli; Jonathan R. Potts; Stephen Harris

2011-02-04

108

Quantum cohomology via vicious and osculating walkers  

E-print Network

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 u(n)-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.

Christian Korff

2012-04-18

109

A random walker on a ratchet  

NASA Astrophysics Data System (ADS)

We analyze a model for a walker moving on a ratchet potential. This model is motivated by the properties of transport of motor proteins, like kinesin and myosin. The walker consists of two feet that are represented as two particles coupled nonlinearly through a bistable potential. In contrast to linear coupling, the bistable potential admits a richer dynamics, where the ordering of the particles can alternate during the walking. The transitions between the two stable states on the bistable potential correspond to a walking with alternating particles. We distinguish between two main walking styles: alternating and no alternating, resembling the hand-over-hand and the inchworm walking in motor proteins, respectively. When the equilibrium distance between the two particles divided by the periodicity of the ratchet is an integer, we obtain a maximum for the current, indicating optimal transport.

Mateos, Jos L.

2005-06-01

110

Spectral Action for Robertson-Walker metrics  

E-print Network

We use the Euler-Maclaurin formula and the Feynman-Kac formula to extend our previous method of computation of the spectral action based on the Poisson summation formula. We show how to compute directly the spectral action for the general case of Robertson-Walker metrics. We check the terms of the expansion up to a_6 against the known universal formulas of Gilkey and compute the expansion up to a_{10} using our direct method.

Ali H. Chamseddine; Alain Connes

2011-05-23

111

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

112

NAVIGATION AND GAIT PLANNING FOR PLANAR WALKER  

Microsoft Academic Search

Locomotion and navigation of a surface walking\\/climbing robot - Planar Walker, based on a novel planar 8-bar mechanism are investigated. The robot moves on a surface through decoupled transverse gaits and turning gaits with finite lengths and finite rotation angles. Motions of the gaits are modeled using planar rigid motion group SE(2). Three point-to-point navigation methods are developed for various

I-Ming Chen; Song Huat Yeo; R. S. Senanayake

113

Dandy-Walker malformation: An incidental finding  

PubMed Central

DandyWalker malformation (DWM) is a rare intracranial congenital abnormality that affects the cerebellum and some of its components; particularly cerebellar vermis, fourth ventricle and is characterized by an enlarged posterior fossa. Although there is an extensive list of signs attributed to DWM, final diagnosis is solely dependent on imaging techniques as there are no signs that are characteristic of DWM. This article reports a case with DWM who was diagnosed by magnetic resonance imaging. PMID:20838490

Tadakamadla, Jyothi; Kumar, Santhosh; Mamatha, G. P.

2010-01-01

114

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

115

Walkers-talon kvijtutkimus : nuorten mielipiteet ja hengailu Kampin alueella.  

E-print Network

??Opinnytetyn tarkoituksena oli tutkia nuorten kymistapoja ja tottumuksia Walkers-talolla ja laajempana yhteyten selvitt hengailukulttuuria ja hengailuun puuttumista Kampin alueella. Yhten tavoitteena oli saada selville nuorten (more)

Luukkonen, Hanne

2010-01-01

116

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102...District 165.102 Security Zone: Walkers Point, Kennebunkport ME. (a) Location...point approximately 500 yards southwest of Walkers Point located at latitude...

2010-07-01

117

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102...District 165.102 Security Zone: Walkers Point, Kennebunkport ME. (a) Location...point approximately 500 yards southwest of Walkers Point located at latitude...

2013-07-01

118

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

...2014-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section...Devices 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are rubber (or...

2014-04-01

119

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102...District 165.102 Security Zone: Walkers Point, Kennebunkport ME. (a) Location...point approximately 500 yards southwest of Walkers Point located at latitude...

2012-07-01

120

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section...Devices 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are rubber (or...

2012-04-01

121

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section...Devices 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are rubber (or...

2011-04-01

122

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102...District 165.102 Security Zone: Walkers Point, Kennebunkport ME. (a) Location...point approximately 500 yards southwest of Walkers Point located at latitude...

2011-07-01

123

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Cane, crutch, and walker tips and pads. 890.3790 Section...Devices 890.3790 Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are rubber (or...

2013-04-01

124

Localization transition of d-friendly walkers Hideki Tanemura and Nobuo Yoshida  

E-print Network

Localization transition of d-friendly walkers Hideki Tanemura and Nobuo Abstract Friendly walkers is a stochastic model obtained from independent one- dimensional* * in Z is occupied by exactly m 2 walkers, then the site increases the prob- abilistic weight

Yoshida, Nobuo

125

Obituary: Robert Mowbray Walker, 1929-2004  

NASA Astrophysics Data System (ADS)

Robert M. Walker, PhD, Professor of Physics in Arts & Sciences and a faculty fellow of the McDonnell Center for the Space Sciences, died of stomach cancer Thursday, 12 February 2004, in Brussels, Belgium. He was 75. Walker worked on the frontiers of space research for more than four decades. Robert Walker was born in Philadelphia on 6 February 1929. His mother was Dorothy Potter and he considered Roger Potter his father though he was not his biological father. His early years were spent in New York City and in upstate New York. He attended the Bronx High School of Science, earned his BS in physics from Union College and in 1954, he received his PhD in particle physics from Yale University. He subsequently joined the General Electric Laboratory in Schenectady, New York where he studied the radiation effects in solids. His work on defects in irradiated copper is still regarded as the definitive work on the topic. In the early 1960s, Walker's discovery of fossil nuclear particle tracks in minerals was instrumental to new developments in geo-chronology and cosmic ray physics. In particular, his discovery of tracks from nuclei heavier than iron opened a new frontier of cosmic ray physics. He subsequently pioneered the use of plastics to detect and count such nuclei in cosmic ray balloon flights. Beginning in 1966, when he moved to Washington University and became the first McDonnell Professor of Physics, his research interests turned more toward space physics. He was the inaugural director of the McDonnell Center, which was established in 1975 by a gift from aerospace pioneer James S. McDonnell. Walker was a member of the NASA committee that allocated samples of the first returned lunar materials, and his laboratory led the way in deciphering their record of lunar, solar system and galactic evolution. Together with Ghislaine Crozaz and other colleagues, Walker made path breaking laboratory studies of the first moon rocks revealing the history of solar radiation and cosmic rays within these samples. He and Dr. Crozaz were married in 1973. In the past two decades, he was a world leader of microanalytical studies of tiny grains preserved for eons in meteorites, culminating in their identification as stardust. More recent achievements include the design of micrometeorite capture cells that were flown aboard NASA's Long Duration Exposure Facility; verification of the extraterrestrial origin of dust particles collected in the upper atmosphere; and the successful search for interstellar grains in meteorites. "Bob was such a dominant force for excellence in our department and the University over so many years, it is hard to grasp that he is gone," said John W. Clark, PhD, chair of physics, the Wayman Crow Professor and a faculty fellow of the McDonnell Center. "His passion for life and science was an inspiration to us all, and his legacy will endure in the work of his many colleagues and the extended family of his former students." Walker led the McDonnell Center, which includes one of the world's largest research groups dedicated to the search for and investigation of extraterrestrial materials, until 1999. "Washington University would be a lesser institution without the contributions of Bob Walker," said William H. Danforth, chancellor emeritus and vice chairman of the Board of Trustees. "He gave us inspiration, enthusiasm, great science and visionary leadership. He built the strength of the McDonnell Center for the Space Sciences. He convinced others of the potential for the modern Department of Earth and Planetary Sciences. He had always the respect and affection of us all." The last two decades of Walker's career were driven by his remarkable vision and his excitement at the prospect of profound discovery. His recognition of the potential importance of the ion microprobe for making isotopic measurements on microscopic samples, and his acquisition in 1982 of a state-of-the-art instrument for the University, led directly to a series of spectacular results. Chief among these was the ident

Schoenherr, Neil T.

2004-12-01

126

Does Mixing Make Residential Ventilation More Effective? Max Sherman, Iain Walker  

E-print Network

Does Mixing Make Residential Ventilation More Effective? Max Sherman, Iain Walker Environmental Effective? Max Sherman and Iain Walker, Lawrence Berkeley Lab ABSTRACT Ventilation dilutes or removes indoor

127

Two Cases of Walker-Warburg Syndrome Complicated by Hydrocephalus  

Microsoft Academic Search

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.

M. Preuss; M. Heckmann; M. Stein; U. Nestler

2010-01-01

128

Designing a new joint for the iXa walker  

E-print Network

In the fall of 2009, the Purple team developed a walker which allows users to rise from a seated position by folding down to provide a set of handles which the user can push off of to aid in the standing process. The walker ...

Grove, Garth S

2010-01-01

129

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

130

The World Function in Robertson-Walker Spacetime  

E-print Network

A method for finding the world function of Robertson-Walker spacetimes is presented. It is applied to find the world function for the $k=0, \\ga=2$, solution. The close point approximation for the Robertson-Walker world function is calculated upto fourth order.

Mark D. Roberts

1999-05-02

131

A business plan for iXa walker  

E-print Network

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

Morton, Stephen A

2010-01-01

132

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

E-print Network

1 Hamlet: Force/Position Controlled Hexapod Walker - Design and Systems Michael R. Fielding , Christopher J. Damaren and Reg Dunlop Abstract--Hamlet is a hexapod walker constructed at the University. Keywords-- position-based compliance control, walking hexapod robot, gait generation I. Introduction

Portland State University

133

Helen M. Walker: Influential in 1929 and Still Cited Today.  

ERIC Educational Resources Information Center

Helen M. Walker contributed to the field of educational research and statistics during a 55-year career. Born in Iowa in 1891, Walker earned a bachelor's degree from Iowa Wesleyan College and taught high school mathematics for nine years. She then taught at the University of Kansas while doing graduate work. One source noted that she was the first

Rice, Marti H.; Stallings, William M.

134

Modeling and gait design of a 6-tetrahedron walker robot  

Microsoft Academic Search

This work describes the use of simulating walker robots to design choreographed gaits for a tetrahedral (TET) walker robot. A TET robot is composed of nodes and struts arranged into tetrahedral cells. The extension and contraction of the struts allows the tetrahedral robot to walk. The Hope College Controls Team so far has built a working 4-TET robot and has

Miguel Abrahantes; Leif Nelson; Peter Doorn

2010-01-01

135

Online approach in adapting user characteristic for robotic walker control  

Microsoft Academic Search

This paper propose an online approach to adapt user's controlling characteristic for robotic walker control. This approach is based on relocating the center of rotation (COR) of the robotic walker and it si implemented online in training. This study aims to aid users that have difficulties in controlling their walking support system. To adapt user's controlling characteristics, a user is

Oscar Chuy Jr; Yasuhisa Hirata; Kazuhiro Kosuge

2005-01-01

136

Modeling and Gait Design of a 4Tetrahedron Walker Robot  

Microsoft Academic Search

This work describes the use of a simulating walking robot to model a tetrahedron walker robot. As a contribution to the gait generation and motion control of the tetrahedron walker robots, a concept has been formulated to implement in the case of choreographic designed gaits.

M. Abrahantes; D. Littio; A. Silver; L. Wendt

2008-01-01

137

Seating motion analysis and its assistance on a robotic walker  

Microsoft Academic Search

In our current research, we are developing a robotic walker system with standing, walking and seating assistance function. Our developing system is based on a walker which is popular assistance device for aged person in normal daily life and realizes the standing and seating motion using the support pad which is actuated by the novel assistance manipulator mechanism with four

Daisuke Chugo; Hajime Ozaki; Yuki Sakaida; Sho Yokota; Kunikatsu Takase

2010-01-01

138

Gait Design and Modeling of a 12Tetrahedron Walker Robot  

Microsoft Academic Search

This work describes the use of a simulating walking robot to model the tetrahedron walker robots being developed at NASA\\/Goddard Space Flight Center. As a contribution to the gait generation and motion control of the tetrahedron walker robots, a concept has been formulated to implement in the case of choreographic designed gaits. This work is part of the contribution of

M. Abrahantes; A. Silver; L. Wendt

2007-01-01

139

Actuating a Simple 3D Passive Dynamic Walker Russ Tedrake  

E-print Network

-- The passive dynamic walker described in this paper is a robot with a minimal number of degrees of freedomActuating a Simple 3D Passive Dynamic Walker Russ Tedrake Computer Science and Artificial used to tune the characteristics of the robot's passive gait. Our sagittal plane model is closely

Tedrake, Russ

140

Sitting motion assistance on a rehabilitation robotic walker  

Microsoft Academic Search

In our current research, we are developing a robotic walker system with standing, walking and sitting assistance function. Our developing system is based on a walker which is popular assistance device for aged person in normal daily life and realizes the standing and sitting motion using the support pad which is actuated by novel assistance manipulator mechanisms with four parallel

Daisuke Chugo; Yuki Sakaida; Sho Yokota; Kunikatsu Takase

2011-01-01

141

16 CFR 1216.2 - Requirements for infant walkers.  

Code of Federal Regulations, 2011 CFR

...ER21JN10.003 Where Vf = Maximum velocity of walker at edge of platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI...ER21JN10.004 Where Vf = Maximum velocity of walker at edge of platform = 4...

2011-01-01

142

16 CFR 1216.2 - Requirements for infant walkers.  

Code of Federal Regulations, 2012 CFR

...ER21JN10.003 Where Vf = Maximum velocity of walker at edge of platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI...ER21JN10.004 Where Vf = Maximum velocity of walker at edge of platform = 4...

2012-01-01

143

16 CFR 1216.2 - Requirements for infant walkers.  

Code of Federal Regulations, 2013 CFR

...ER21JN10.003 Where Vf = Maximum velocity of walker at edge of platform = 4 ft/sec Vo = Initial velocity = 0 WCAMI = Measured weight of CAMI...ER21JN10.004 Where Vf = Maximum velocity of walker at edge of platform = 4...

2013-01-01

144

Reunions of three dissimilar vicious walkers  

SciTech Connect

We study the behavior of three vicious random walkers which diffuse freely in one dimension with arbitrary diffusivities b/sub 1//sup 2/, b/sub 2//sup 2/, b/sub 3//sup 2/, except that their paths may not cross. The full distribution function is calculated exactly in the continuum limit; the exponent psi/sub 3/ governing the decay of the probability R/sub n//sup (3)/ approx. 1/n/sup psi3/ of a simultaneous reunion of all three walkers after n steps is found to vary continuously according to psi/sub 3/ = 1 + ..pi../cos/sup -1//b/sub 2//sup 2//(b/sub 1//sup 2/ + b/sub 2//sup 2/)(b/sub 2//sup 2/ + b/sub 3//sup 2/))/sup 1/2/. This variation has consequences for various interfacial wetting transitions in (1 + 1) dimensions. It may also be related heuristically to the marginality of direct interface-wall interactions decaying as W/sub 0//l/sup 2/ in the intermediate fluctuation regime of (1 + 1)-dimensional wetting, where exponents varying continuously with W/sub 0/ have recently have found.

Fisher, M.E.; Gelfand, M.P.

1988-10-01

145

Precise Asymptotics for a Random Walker's Maximum  

E-print Network

We consider a discrete time random walk in one dimension. At each time step the walker jumps by a random distance, independent from step to step, drawn from an arbitrary symmetric density function. We show that the expected positive maximum E[M_n] of the walk up to n steps behaves asymptotically for large n as, E[M_n]/\\sigma=\\sqrt{2n/\\pi}+ \\gamma +O(n^{-1/2}), where \\sigma^2 is the variance of the step lengths. While the leading \\sqrt{n} behavior is universal and easy to derive, the leading correction term turns out to be a nontrivial constant \\gamma. For the special case of uniform distribution over [-1,1], Coffmann et. al. recently computed \\gamma=-0.516068...by exactly enumerating a lengthy double series. Here we present a closed exact formula for \\gamma valid for arbitrary symmetric distributions. We also demonstrate how \\gamma appears in the thermodynamic limit as the leading behavior of the difference variable E[M_n]-E[|x_n|] where x_n is the position of the walker after n steps. An application of these results to the equilibrium thermodynamics of a Rouse polymer chain is pointed out. We also generalize our results to L\\'evy walks.

Alain Comtet; Satya N. Majumdar

2005-06-08

146

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. PMID:21041520

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

2012-01-01

147

Dandy-Walker variant in Coffin-Siris syndrome.  

PubMed

We describe a five-month-old male infant with Coffin-Siris syndrome, the so-called Dandy-Walker variant (hypoplasia of the cerebellar vermis with cystic dilatation of the fourth ventricle, but without enlargement of the posterior fossa), and partial agenesis of the corpus callosum. Dandy-Walker malformation and mega cisterna magna, but not Dandy-Walker variant, have been reported in Coffin-Siris syndrome. The presence of Dandy-Walker variant in the infant we described confirms that the full continuum of the Dandy-Walker complex can occur in Coffin-Siris syndrome. The yet unidentified gene(s) for the syndrome may be related to the development of the hindbrain. PMID:11298377

Imai, T; Hattori, H; Miyazaki, M; Higuchi, Y; Adachi, S; Nakahata, T

2001-04-22

148

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

149

Designing stimulus-sensitive colloidal walkers  

E-print Network

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 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 functionalization.

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

2014-02-09

150

Localization Issues for Robertson-Walker Branes  

E-print Network

We discuss some of the localization issues associated with the embedding of Robertson-Walker type Randall-Sundrum branes in a bulk $AdS_5$. Specifically, we show that of the branes which are embeddable in $AdS_5$ the geometry associated with $M_4$ and $dS_4$ branes warps away from the brane while that associated with $AdS_4$ and $RW$ branes of any spatial 3-curvature antiwarps away from the brane. We discuss the gravitational fluctuations around an $M_4$ brane and analyze the specific role played by a delta function singularity at the brane. We show how a bulk sine-Gordon scalar field can without any fine-tuning naturally lead to localization of gravity around an $M_4$ brane.

Philip D. Mannheim

2008-07-23

151

Localization Issues for Robertson-Walker Branes  

NASA Astrophysics Data System (ADS)

We discuss some of the localization issues associated with the embedding of Robertson-Walker type Randall-Sundrum branes in a bulk AdS5. Specifically, we show that of the branes which are embeddable in AdS5 the geometry associated with M4 and dS4 branes warps away from the brane while that associated with AdS4 and RW branes of any spatial 3-curvature antiwarps away from the brane. We discuss the gravitational fluctuations around an M4 brane and analyze the specific role played by a delta function singularity at the brane. We show how a bulk sine-Gordon scalar field can without any fine-tuning naturally lead to localization of gravity around an M4 brane.

Mannheim, Philip D.

2002-07-01

152

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

153

SIR GILBERT WALKER AND A CONNECTION BETWEEN EL NIO AND STATISTICS: FROM "TYPICAL CAMBRIDGE DON" TO  

E-print Network

1 SIR GILBERT WALKER AND A CONNECTION BETWEEN EL NI�O AND STATISTICS: FROM "TYPICAL CAMBRIDGE DON Science, V. 17, pp. 97-112. #12;2 OPENING QUOTE � Sir Gilbert Walker (1925) -- "It is a natural or amplitude." #12;3 OUTLINE (1) Background (2) Sir Gilbert Walker (3) Yule-Walker Equations (4) Reaction

Katz, Richard

154

Localization transition of d-friendly walkers Hideki Tanemura and Nobuo Yoshida  

E-print Network

Localization transition of d-friendly walkers Hideki Tanemura and Nobuo Yoshida Chiba University and Kyoto University Abstract Friendly walkers is a stochastic model obtained from independent one is occupied by exactly m 2 walkers, then the site increases the prob- abilistic weight for the walkers

Yoshida, Nobuo

155

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

E-print Network

On Three and Four Vicious Walkers William Y. C. Chen1 , Donna Q. J. Dou2 , Terence Y. J. Zhang3 for three lattice walkers and use this principle to reduce the enumeration of configurations of three vi- cious walkers to that of configurations of two vicious walkers. Pre- cisely, the reflection principle

Chen, Bill

156

An interactive robotic walker for assisting elderly mobility in senior care unit  

Microsoft Academic Search

This paper describes a robotic walker, Johnnie, that provides assistance to mobility-challenged people, especially elderly people. Our walker is modified from a conventional unpowered four-wheel walker by equipping motors, sensors and some safety devices, providing mobility and stability to it. In our software system, we provide two modes: (1) autonomous mode in which the walker can autonomously navigate to the

Kuan-Ting Yu; Chi-Pang Lam; Ming-Fang Chang; Wei-Hao Mou; Shi-Huan Tseng; Li-Chen Fu

2010-01-01

157

Implementation of multi-walker quantum walks with cavity grid  

E-print Network

We show how multi-walker quantum walks can be implemented in a quantum quincunx created via cavity quantum electrodynamics. The implementation of a quantum walk with a multi-walker opens up the interesting possibility to introduce entanglement and more advanced walks. With different coin tosses and initial states the multi-walker quantum walk shows different probability distributions which deviate strongly from the classical random walks with quadratic enhanced spreadings and localization effects. By introducing decoherence, the transition from quantum walks to the classical versions is observed. We introduce the average fidelity decay as a signature to investigate the decoherence-induced irreversibility of quantum walks.

Peng Xue

2012-03-27

158

Interacting walkers on the Cayley tree, and polymer statistics  

SciTech Connect

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

Priezzhev, V.B.

1986-09-01

159

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...

160

On the Hadamard condition on Robertson-Walker spacetime  

E-print Network

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

Jan Tichavsky

2006-09-04

161

Increasing the dimensionality of quantum walks using multiple walkers  

E-print Network

We show that with the addition of multiple walkers, quantum walks on a line can be transformed into lattice graphs of higher dimension. Thus, multi-walker walks can simulate single-walker walks on higher dimensional graphs and vice versa. This exponential complexity opens up new applications for present-day quantum walk experiments. We discuss the applications of such higher-dimensional structures and how they relate to linear optics quantum computing. In particular we show that multi-walker quantum walks are equivalent to the BosonSampling model for linear optics quantum computation proposed by Aaronson & Arkhipov. With the addition of control over phase-defects in the lattice, which can be simulated with entangling gates, asymmetric lattice structures can be constructed which are universal for quantum computation.

Peter P. Rohde; Andreas Schreiber; Martin Stefanak; Igor Jex; Alexei Gilchrist; Christine Silberhorn

2012-05-09

162

Aktiivisia, sosiaalisia ja innokkaita? : Tapaustutkimus Helsingin Walkers-vapaaehtoistyntekijist.  

E-print Network

??Opinnytety on tehty tilaustyn Aseman Lapsille Helsingin Walkersin vapaaehtoistyntekijist. Walkers-toiminta on ennaltaehkisev nuorisotyt, jonka perustan muodostavat aikuiset vapaaehtoistyntekijt. Kyse on turvallisen ympristn luomisesta alle 18-vuotiaille (more)

Grnlund, Hanna

2011-01-01

163

On the construction of Fermi-Walker transported frames  

E-print Network

We consider tetrad fields as reference frames adapted to observers that move along arbitrary timelike trajectories in spacetime. By means of a local Lorentz transformation we can transform these frames into Fermi-Walker transported frames, which define a standard of non-rotation for accelerated observers. Here we present a simple prescription for the construction of Fermi-Walker transported frames out of an arbitrary set of tetrad fields.

J. W. Maluf; F. F. Faria

2008-04-15

164

Codimension two marginally trapped submanifolds in Robertson-Walker spaces  

E-print Network

We give a local characterization of codimension two submanifolds which are marginally trapped in Robertson-Walker spaces, in terms of an algebraic equation to be satisfied by the height function. We prove the existence of a large number of local solutions. We refine the description in the case of curves with null acceleration in three-dimensional spaces Robertson-Walker spaces, and in the case of codimension two submanifolds whose second fundamental form is null

Henri Anciaux; Nastassja Cipriani

2014-06-20

165

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

166

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

167

Scatterometers observe the variation of the Walker circulation  

Microsoft Academic Search

The variation of the Walker circulation is closely related to the onset of El Nio-Southern Oscillation (ENSO) events [Kousky, 1984], so observing the Walker circulation can lead to better understanding of ENSO events. Wind data from the NASA Scatterometer (NSCAT), Quick Scatterometer (QuikSCAT), and European Remote Sensing Satellite-1\\/2 (ERS-1\\/2) were merged into one data set in a 11 grid covering

Jiayi Pan; Xiao-Hai Yan; Quanan Zheng; W. Timothy Liu

2001-01-01

168

Design and control of JAIST active robotic walker  

Microsoft Academic Search

This paper presents the design and control of a novel assistive robotic walker that we call JAIST active robotic walker (JARoW).\\u000a JARoW is developed to provide potential users with sufficient ambulatory capability in an efficient, cost-effective way. Specifically,\\u000a our focus is placed on how to allow easier maneuverability by creating a natural interface between the user and JARoW. For\\u000a the

Geunho Lee; Takanori Ohnuma; Nak Young Chong

2010-01-01

169

* Corresponding author. Tel.: #44-1570-424736. E-mail address: walker@lamp.ac.uk (M.J.C. Walker)  

E-print Network

* Corresponding author. Tel.: #44-1570-424736. E-mail address: walker@lamp.ac.uk (M.J.C. Walker for the Late Pleistocene M.J.C. Walker *, S. BjoK rck , J.J. Lowe , L.C. Cwynar , S. Johnsen , K.-L. Knudsen Quaternary sequences (Lowe & Walker, 1997). The problem is most apparent during the transition from the Last

Wohlfarth, Barbara

170

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

171

X-1E with Pilot Joe Walker  

NASA Technical Reports Server (NTRS)

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

1958-01-01

172

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

Federal Register 2010, 2011, 2012, 2013

...Mittal, Formerly Known as Mittal Steel Walker Wire, a Subsidiary of Arcelor Mittal...Mittal, formerly known as Mittal Steel Walker Wire, a subsidiary of Arcelor Mittal...issued for all workers of Mittal Steel Walker Wire, Inc., Ferndale, Michigan,...

2011-03-14

173

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

Federal Register 2010, 2011, 2012, 2013

...at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico AGENCY...Walker Ridge 249 in the Outer Continental Shelf. The purpose of the safety...at Walker Ridge 249, Outer Continental Shelf FPSO, Gulf of Mexico in...

2010-04-16

174

Quantum Walk-based Generation of Entanglement Between Two Walkers  

E-print Network

Quantum walks can be used either as tools for quantum algorithm development or as entanglement generators, potentially useful to test quantum hardware. We present a novel algorithm based on a discrete Hadamard quantum walk on a line with one coin and two walkers whose purpose is to generate entanglement between walkers. We provide several classical computer simulations of our quantum algorithm in which we show that, although the asymptotical amount of entanglement generated between walkers does not reach the highest degree of entanglement possible at each step for either coin measurement outcome, the entanglement ratio (entanglement generated/highest value of entanglement possible, for each step) tends to converge, and the actual convergence value depends on the coin initial state and on the coin measurement outcome. Furthermore, our numerical simulations show that, for the quantum walks used in our algorithm, the value towards which entanglement ratio converges also depends on the position probability distribution symmetry of a quantum walk computed with one single walker and the same coin initial state employed in the corresponding quantum walk with two walkers.

Salvador E. Venegas-Andraca; Sougato Bose

2009-01-26

175

[Congenital generalized lipodystrophy in a patient with Dandy Walker anomaly].  

PubMed

The objective of this study is to describe the unexpected association between the congenital generalized lipodystrophy (CGL) and Dandy Walker anomaly. We report the case of a 1-year-old infant who was hospitalized at her fourth month of life with Dandy Walker anomaly diagnosis and an increased social risk. During her hospitalization, she developed progressively: acromegaloid aspect, triangular fascia, hirsutism, lipoatrophy, muscle hypertrophy, clitoromegaly, abdominal distention, progressive hepatomegaly, and hypertriglyceridemia. This led to the clinical diagnosis of congenital generalized lipodystrophy. Importance should be given to the examination of clinical aspects as well as the interdisciplinary follow-up for proper detection of insulin resistance and diabetes, early puberty, cardiomyopathy, among others. In case of Dandy Walker anomaly, it should be checked the evolution to search intracranial hypertension signs. Due to its autosomal recessive nature, it is important to provide genetic counseling to the parents. PMID:25192534

Luna, Cecilia Ins; Fernndez Cordero, Marisa; Escruela, Romina; Sierra, Valeria; Crdoba, Antonela; Goi, Ignacio Mara; Berridi, Ricardo

2014-10-01

176

Multiple Walkers in the Wang-Landau Algorithm  

SciTech Connect

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

Brown, G

2005-12-28

177

Joe Walker in pressure suit with X-1E  

NASA Technical Reports Server (NTRS)

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

1958-01-01

178

Quantum Walk-based Generation of Entanglement Between Two Walkers  

E-print Network

Quantum walks can be used either as tools for quantum algorithm development or as entanglement generators, potentially useful to test quantum hardware. We present a novel algorithm based on a discrete Hadamard quantum walk on a line with one coin and two walkers whose purpose is to generate entanglement between walkers. We provide several classical computer simulations of our quantum algorithm in which we show that, although the asymptotical amount of entanglement generated between walkers does not reach the highest degree of entanglement possible at each step for either coin measurement outcome, the entanglement ratio (entanglement generated/highest value of entanglement possible, for each step) tends to converge, and the actual convergence value depends on the coin initial state and on the coin measurement outcome. Furthermore, our numerical simulations show that, for the quantum walks used in our algorithm, the value towards which entanglement ratio converges also depends on the position probability distri...

Venegas-Andraca, Salvador E

2009-01-01

179

Dandy Walker Variant and Bipolar I Disorder with Graphomania  

PubMed Central

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

Karakas Ugurlu, Gorkem; Cakmak, Selcen

2014-01-01

180

Tubing analysis and selection process for the frame of the IXA walker  

E-print Network

A thorough analysis and test of the frame for a walker was conducted in order to select the optimal size tubing for the walker. Initially a rough first order bending analysis was completed to make an initial decision on ...

Cummings, Lucas (Lucas Robert)

2010-01-01

181

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

E-print Network

to David Walker Hazem M. Kalaji � Vasilij Goltsev � Karolina Bosa � Suleyman I. Allakhverdiev � Reto J 2012 � Springer Science+Business Media B.V. 2012 Abstract This review is dedicated to David Walker

Govindjee

182

Walker Branch Throughfall Displacement Experiment Data Report: Site Characterization, System Performance, Weather,  

E-print Network

Walker Branch Throughfall Displacement Experiment Data Report: Site Characterization, SystemWolfe Elizabeth G. O'NeillElizabeth G. O'Neill DOI: 10.3334/CDIAC/vrc.ndp078 #12;ORNL/CDIAC-134 NDP-078A Walker

183

States of Low Energy on Robertson-Walker Spacetimes  

E-print Network

We construct a new class of physical states of the free Klein-Gordon field in Robertson-Walker spacetimes. This is done by minimizing the expectation value of smeared stress-energy. We get an explicit expression for the state depending on the smearing function. We call it a state of low energy. States of low energy are an improvement of the concept of adiabatic vacua on Robertson-Walker spacetimes. The latter are approximations of the former. It is shown that states of low energy are Hadamard states.

Heiner Olbermann

2007-04-23

184

Static forms of the Robertson-Walker spacetimes  

E-print Network

It is shown that only the maximally-symmetric spacetimes can be expressed in both the Robertson-Walker form and in static form - there are no other static forms of the Robertson-Walker spacetimes. All possible static forms of the metric of the maximally-symmetric spacetimes are presented as a table. The findings are generalized to apply to functionally more general spacetimes: it is shown that the maximally symmetric spacetimes are also the only spacetimes that can be written in both orthogonal-time isotropic form and in static form.

M. Ibison

2007-04-24

185

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

E-print Network

Rollating walkers are popular mobility aids used by older adults to improve balance control. There is a need to automatically recognize the activities performed by walker users to better understand activity patterns, mobility issues and the context in which falls are more likely to happen. We design and compare several techniques to recognize walker related activities. A comprehensive evaluation with control subjects and walker users from a retirement community is presented.

Omar, Farheen; Truszkowski, Jakub; Poupart, Pascal; Tung, James; Caine, Allen

2012-01-01

186

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

ERIC Educational Resources Information Center

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

Jago, Carol

187

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

ERIC Educational Resources Information Center

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

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

2006-01-01

188

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...petition filed on behalf of workers at The Walker Auto Group, Inc., Miamisburg, Ohio...should be eligible for TAA because the Walker Auto Group, Inc., Miamisburg,...

2010-05-05

189

A Synthetic DNA Walker for Molecular Transport Jong-Shik Shin and Niles A. Pierce*,,  

E-print Network

A Synthetic DNA Walker for Molecular Transport Jong-Shik Shin and Niles A. Pierce*,, Departments. Sherman and Seeman recently demonstrated a bipedal DNA walker that locomotes in an inchworm fashion at each step. Real-time monitoring of walker movement is achieved via multiplexed fluorescence quenching

Pierce, Niles A.

190

CH 302 10-11am MTWThF Spring 2012 Instructor Deb Walker  

E-print Network

CH 302 10-11am MTWThF Spring 2012 Instructor Deb Walker Syllabus: CH302 Principles of Chemistry II, culminating in written quizzes and exams. Course: CH302 General Chemistry Instructor: D.Walker, Ph://courses.utexas.edu. Instructor: Deborah R. Walker, Ph.D. Contact: debwalker@utexas.edu Office: Office Hours: (see online version

191

The Kneed Walker for Human Pose Tracking Marcus A. Brubaker David J. Fleet  

E-print Network

The Kneed Walker for Human Pose Tracking Marcus A. Brubaker David J. Fleet Department of Computer Science University of Toronto {mbrubake,fleet}@cs.toronto.edu Abstract The Kneed Walker is a physics tracking comprises the Kneed Walker prior, a 3D kinematic model constrained to be consistent

Toronto, University of

192

When and How Much Should Random Walkers Proliferate for a Fast and Efficient Search?  

E-print Network

When and How Much Should Random Walkers Proliferate for a Fast and Efficient Search? Subrata Nandi The time-dependent coverage of a network by a varying number of random walkers is considered. Broadening speed and efficiency for estimation of the optimal number of walkers is a non-trivial issue, as speed

Ganguly, Niloy

193

Sky-walker:An Integrated Solution for Network and Computer Security  

E-print Network

Sky-walker:An Integrated Solution for Network and Computer Security A DISSERTATION PRESENTED BY FU;Abstract of the Dissertation Sky-walker:An Integrated Solution for Network and Computer Security by Fu distinct approaches to deal with differ- ent security threats and we also provide an infrastructure, sky-walker

Chiueh, Tzi-cker

194

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

E-print Network

DH201 USDA Farm Service Agency Disaster Assistance1 Michael T. Olexa and Travis Walker2 1 and Recovery Education Module. There are ten Disaster Handbook documents by Olexa and Walker: DH138, DH199, DH, and Travis Walker, student, Levin College of Law, University of Florida, Gainesville, FL 32611. Note

Watson, Craig A.

195

YULE-WALKER EQUATIONS APPLIED TO HESSIANS OF THE CHARACTERISTIC FUNCTION FOR IMPROVED AR ESTIMATION  

E-print Network

YULE-WALKER EQUATIONS APPLIED TO HESSIANS OF THE CHARACTERISTIC FUNCTION FOR IMPROVED AR ESTIMATION@eng.tau.ac.il ABSTRACT Estimation of the autoregressive (AR) parameters of an AR process often involves applying Yule-Walker-based estimate. Index Terms-- autoregressive, Yule-Walker, char- acteristic function, Hessian, charrelation

Yeredor, Arie

196

DNA walker circuits: computational potential, design, and verification Frits Dannenberg1  

E-print Network

DNA walker circuits: computational potential, design, and verification Frits Dannenberg1 , Marta `walker' systems which were recently shown to be capable of navigating a programmable track tethered and forming composable circuits. We find that systems of multiple walkers have severely limited potential

Oxford, University of

197

Walkers on the cycle and the grid N.C. Wormald  

E-print Network

Walkers on the cycle and the grid J. D´iaz X. P´erez M.J. Serna N.C. Wormald Abstract We present further applications in computer science. We propose what we call the walkers model, defined as follows. A connected graph G = (V, E) with |V | = N is given, and a number w of walkers (agents). Also given

Wormald, Nick

198

CH 301 8-9:30am TTh Spring 2012 Instructor D. Walker  

E-print Network

CH 301 8-9:30am TTh Spring 2012 Instructor D. Walker Syllabus: CH301 Principles of Chemistry I: CH301 Principles of Chemistry Instructor: D. R. Walker, Ph.D.; debwalker@utexas.edu Office: WEL 4://courses.utexas.edu Course Gradebook and HW: http://quest.cns.utexas.edu Instructor: Deborah R. Walker, Ph.D. Contact

199

PREFERENCES FOR INTERFACE DESIGN FOR A NAVIGATION ASSISTANT ON A WHEELED WALKER  

E-print Network

PREFERENCES FOR INTERFACE DESIGN FOR A NAVIGATION ASSISTANT ON A WHEELED WALKER Judith T. Matthews their way in familiar and unfamiliar environments, we are developing a navigation assistant, or iWalker on walkers are currently in development, including the Personal Aid for Mobility and Monitoring (PAMM) [9

Kulyukin, Vladimir

200

SLEEP-DEPENDENT MOTOR MEMORY PLASTICITY IN THE HUMAN M. P. WALKER,a,b  

E-print Network

SLEEP-DEPENDENT MOTOR MEMORY PLASTICITY IN THE HUMAN BRAIN M. P. WALKER,a,b * R. STICKGOLD,b D of sleep- dependent learning in both humans and animals (Walker and Stickgold, 2004), already complemented reviews see Walker, in press). Demonstrations of over- night, sleep-dependent learning have now been

Walker, Matthew P.

201

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

E-print Network

Mechanical Hip Actuation Of A 2-D Passive-Dynamics Based Walker TAM 492 ­ 3 Credits Matt Strasberg at one point or another, life is not constantly downhill, and it's probably important to have a walker, not controlling ever angle in the walker, but instead lending small amounts of energy to the device through

Ruina, Andy L.

202

Localization transition of (d + 1)-friendly walkers Hideki Tanemura and Nobuo Yoshida  

E-print Network

Localization transition of (d + 1)-friendly walkers Hideki Tanemura and Nobuo Yoshida Chiba University and Kyoto University Abstract Friendly walkers is a stochastic model obtained from one #21; 1, then the probabilistic weight for the walkers increases by multiplicative factor exp(#12; m

203

Minimal predicted distance: a kinematic cue to investigate collision avoidance between walkers  

E-print Network

Minimal predicted distance: a kinematic cue to investigate collision avoidance between walkers A walkers was only studied in a frontal task to investigate the influence of gender and height to avoidance manoeuvres in locomotor trajectories of two walkers. Based on the assumption of a reciprocal

Paris-Sud XI, Université de

204

Thad G. Walker Professor of Physics, University of Wisconsin-Madison  

E-print Network

Vita Thad G. Walker Professor of Physics, University of Wisconsin-Madison Education Ph.D., Physics . Publications In Refereed Journals: 107 Book: William Happer, Yuan-Yu Jau, and Thad G. Walker, Optically Pumped, Ronald T. Wakai, and Thad G. Walker, Opt. Lett. 37, 2247 (2012). "Breakdown of Angular Momentum Selection

Walker, Thad G.

205

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

E-print Network

Comparative Analysis of Probabilistic Models for Activity Recognition with an Instrumented Walker,msinn,jmtruszk,ppoupart,j6tung}@uwaterloo.ca, adcaine@alumni.uwaterloo.ca Abstract Rollating walkers are popular mobility the activities performed by walker users to better understand activity patterns, mo- bility issues

Poupart, Pascal

206

A Study of Information Dissemination Under Multiple Random Walkers and Replication Mechanisms  

E-print Network

A Study of Information Dissemination Under Multiple Random Walkers and Replication Mechanisms large-scale. Mul- tiple random walkers have been proposed in the recent past as a suitable mechanism walkers mechanism is studied and ana- lyzed under a different and novel perspective that allows

Stavrakakis, Ioannis

207

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

E-print Network

LATERALIZATION OF SOUNDS USING BONE-CONDUCTION HEADSETS Raymond M. Stanley and Bruce N. Walker Sonification Lab, School of Psychology Georgia Institute of Technology, Atlanta, GA 30332-0170 bruce.walker display tasks, including wayfinding (Walker & Lindsay, 2006) and segregation of simultaneous speech

208

Walker-instants Definition 1 An instant of an event struc-  

E-print Network

Walker-instants Definition 1 An instant of an event struc- ture is a triple (P, C, F structure unsatisfactory. Can we do better with Walker instants? 3 #12;The past determines everything Lemma past equals P. 4 #12;Walker instants generate a linear order. Let I(W) be the set of instants

van Lambalgen, Michiel

209

On the Geometric Reduction of Controlled Three-Dimensional Bipedal Robotic Walkers  

E-print Network

On the Geometric Reduction of Controlled Three-Dimensional Bipedal Robotic Walkers Aaron D. Ames1 is to apply methods from geometric mechan- ics to the analysis and control of bipedal robotic walkers. We bipedal robotic walkers are naturally modeled as hybrid systems, which are inherently nonsmooth, in order

Sastry, S. Shankar

210

ccsd-00004649,version2-30Jun2005 THREE OSCULATING WALKERS  

E-print Network

ccsd-00004649,version2-30Jun2005 THREE OSCULATING WALKERS MIREILLE BOUSQUET-M´ELOU To Tony Guttmann, on the occasion of his 60th birthday Abstract. We consider three directed walkers on the square lattice, which-crossing configuration of walks. This configuration is said to be osculating if the walkers never share an edge

Paris-Sud XI, Université de

211

hal-00182431,version1-25Oct2007 Large scale dynamics of the Persistent Turning Walker  

E-print Network

hal-00182431,version1-25Oct2007 Large scale dynamics of the Persistent Turning Walker model of fish on fish motion, the so-called Persistent Turning Walker (PTW) model, which involves an Ornstein and for stimulating discussions. Key words: Individual based model, Fish behavior, Persistent Turning Walker model

Paris-Sud XI, Université de

212

William R. Walker Graduate Research Fellow Award Virginia Water Resources Research Center  

E-print Network

William R. Walker Graduate Research Fellow Award Virginia Water Resources Research Center 2012 The Virginia Water Resources Research Center offered the first William R. Walker Graduate Research Fellow Award form below. #12;Application Form William R. Walker Graduate Research Fellow Award* Virginia

Virginia Tech

213

Does Human mtDNA Recombine? Adam Eyre-Walker,1  

E-print Network

Does Human mtDNA Recombine? Adam Eyre-Walker,1 Philip Awadalla2 1 Centre for the Study of Evolution et al. 1991) or of recombination (Awadalla et al. 1999; Eyre-Walker et al. 1999a; Hagelberg et al et al. 1996), but only one putative recombinant has been de- Correspondence to: Adam Eyre-Walker

Eyre-Walker, Adam

214

Non-Walker Self-Dual Neutral Einstein Four-Manifolds of Petrov Type III  

E-print Network

Non-Walker Self-Dual Neutral Einstein Four-Manifolds of Petrov Type III By Andrzej Derdzinski of all non-Walker self- dual oriented Einstein four-manifolds (M, g) of the neutral metric signature. Such (M, g), also referred to as the non-Walker, type III four-dimensional Jordan-Osserman manifolds [7

Derdzinski, Andrzej

215

How clonal are human mitochondria? Adam Eyre-Walker*  

E-print Network

How clonal are human mitochondria? Adam Eyre-Walker* , Noel H. Smith and John Maynard Smith Centre composition bias. There must either be `hypervariable' sites or recombination between mitochondria. We present that recombination has occurred between mitochondrial lineages in humans. Keywords: mitochondria; recombination

Eyre-Walker, Adam

216

Do mitochondria recombine in humans? Adam Eyre-Walker  

E-print Network

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

Eyre-Walker, Adam

217

General Transformation Formulas for Fermi-Walker Coordinates  

E-print Network

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 formulas for coefficients and the Jacobian matrix are given.

David Klein; Peter Collas

2007-12-22

218

Efficient Bipedal Robots Based on Passive-Dynamic Walkers  

Microsoft Academic Search

Passive-dynamic walkers are simple mechanical devices, composed of solid parts connected by joints, that walk stably down a slope. They have no motors or controllers, yet can have remarkably humanlike motions. This suggests that these machines are useful models of human locomotion; however, they cannot walk on level ground. Here we present three robots based on passive-dynamics, with small active

Steve Collins; Andy Ruina; Russ Tedrake; Martijn Wisse

2005-01-01

219

Particle creation in a Robertson-Walker Universe revisited  

E-print Network

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

F. Pascoal; C. Farina

2007-01-04

220

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

221

Finding the Right Formula: Edwin H. Walker Jr  

ERIC Educational Resources Information Center

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

Keels, Crystal L.

2005-01-01

222

Moments of vicious walkers and Mbius graph expansions  

E-print Network

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

Makoto Katori; Naoaki Komatsuda

2002-12-19

223

f-symbols in Robertson-Walker space-times  

E-print Network

In a Robertson-Walker space-time a spinning particle model is investigated and we show that in a stationary case, there exists a class of new structures called f-symbols which can generate reducible Killing tensors and supersymmetry algebras.

Florian Catalin Popa; Ovidiu Tintareanu-Mircea

2004-12-16

224

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

225

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

226

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

227

SOIL MOISTURE ESTIMATION USING REMOTE SENSING Jeffrey Walker1  

E-print Network

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

Walker, Jeff

228

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

Microsoft Academic Search

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

Jeffrey R. Pier; Brian Mason

2005-01-01

229

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

ERIC Educational Resources Information Center

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

Hamilton, Cynthia

1988-01-01

230

Persons using crutches, canes or walkers: Disabled Persons  

E-print Network

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

Meyers, Steven D.

231

Random Walker Ranking for NCAA Division I-A Football  

E-print Network

Random Walker Ranking for NCAA Division I-A Football Thomas Callaghan, Peter J. Mucha, and Mason A in accurately ranking or even agreeing on a ranking methodology for college football lies in two factors;Despite the obvious difficulties, many systems for ranking college football teams have been promoted

Porter, Mason A.

232

Hamlet: force\\/position controlled hexapod walker - design and systems  

Microsoft Academic Search

Hamlet is a hexapod walker constructed at the University of Canterbury, New Zealand, to test the effectiveness of combined force and position control to achieve robust, adaptable walking over rough and unknown environments. In particular the authors propose that compliance behaviours using the horizontal force measured at the feet will allow the robot to navigate slippery and dynamic surfaces such

Michael R. Fielding; Reg Dunlop; Christopher J. Damaren

2001-01-01

233

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

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

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

234

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

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

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

235

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

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

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

236

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

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

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

237

Resisting the Fixity of Suburban Space: The Walker as Rhetorician  

Microsoft Academic Search

This essay examines homogeneous, suburban commercial streets commonly found in the United States. These streets employ minutely regulated systems of order organized under the logic of automobile traffic. In a society where consumerism reigns, these streets and the spatial order they entail contribute significantly to the ideologies of everyday life. Because these streets rely almost entirely on driving, the walker

Robert J. Topinka

2012-01-01

238

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

E-print Network

Some Issues in Creating `Invertebrate' Robots I.D. Walker Clemson University, Dept. Electrical issues involved in the design, analysis, and implementation of `invertebrate- like' robots. Using as case examples several novel `trunk and tentacle' robot arms recently constructed at Clemson Uni- versity, we

239

A rehabilitation walker with standing and walking assistance  

Microsoft Academic Search

This paper proposes a robotic walker system with standing and walking assistance function. Our system focuses on domestic use for aged person who needs nursing in their daily life. Our key ideas are two topics. The first topic is combination of standing assistance function and walking assistance function. In previous works, many assistance devices are specialized in only ldquostanding-up operationrdquo

Daisuke Chugo; Tai Asawa; Takuya Kitamura; Songmin Jia; Kunikatsu Takase

2008-01-01

240

Dr. Ronald A. Walker W-255K Olmsted Building  

E-print Network

Dr. Ronald A. Walker W-255K Olmsted Building Dept. of Computer Science and Math- ematical Sciences, Huntingdon, PA, 2006-2007 Ross Assistant Professor, The Ohio State University, Columbus, OH, 2003-2006 Honors, University of Richmond, summer 1996, 1997 - 1998 Advisor: Dr. William T. Ross Topic: Solutions

Walker, Ronald A.

241

THE LARVA OF LEUCORRHINIA PATRICIA WALKER (ODONATA: LIBELLULIDAE)  

Microsoft Academic Search

The final-stadium larva of Leucorrhinia patricia Walker is described from six exuviae with associated teneral adults collected in northern British Columbia. L. patricia belongs to the group of nearctic Leucorrhinia that has larvae with three ventral stripes. The larvae are very similar to those L. hudsonica (Slys) larvae that are small and lack dorsal spines. Several characters help to separate

Rex D. Kenner; Robert A. Cannings; Sydney G. Cannings

2000-01-01

242

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

Federal Register 2010, 2011, 2012, 2013

...test table surface, and the maximum velocity at the edge of the test table platform...incident data indicates a need to change velocities in the step test. Response: As discussed...critical parameter of the step test is the velocity of a walker with a child in it....

2010-06-21

243

Non-motorized vehicles and walkers: going for broke  

Microsoft Academic Search

Many emergency department visits are for trauma resulting from mishaps while using wheeled sports equipment. While these injuries among children and adolescents are common, much of the variation in injury frequency and severity depends on the age of the child and protective equipment used. This article will discuss injuries related to baby walkers as well as various wheeled sporting equipment,

Elizabeth C Powell

2003-01-01

244

Mary Lily Walker of Dundee: Social Worker and Reformer  

Microsoft Academic Search

Mary Lily Walker (1863-1913) was Dundee's leading activist in matters of social welfare and social reform during the late Victorian and Edwardian period. As the Honourary Superintendent of the Dundee Social Union (DSU), she initiated a number of social welfare services in Dundee for working class women and children. The Grey Lodge Settlement Association, a bustling community centre in present-day

Myra Baillie

1996-01-01

245

Robotic walkers from a clinical point of view: Feature-based classification and proposal of the UFES Walker  

Microsoft Academic Search

This paper presents a critical review of the state of the art of robotic walkers, emphasizing on the clinical applicability of the main features reported in such systems. A feature-based classification is proposed along with the presentation of the possible clinical scenarios, highlighting the potential of these devices for modern physical therapy practice. Based on the classification, the development of

Arlindo Elias; Anselmo Frizera; Teodiano Freire Bastos; Carlos Valadao

2012-01-01

246

Dynamic micromagnetic simulation of domain wall around the Walker breakdown in ferromagnetic nanowires driven magnetic pulse  

NASA Astrophysics Data System (ADS)

We have investigated the domain wall dynamic around the Walker breakdown field in ferromagnetic nanowires by means of micromagnetic simulation. The simulation is driven by short magnetic pulse 1-ns length with a systematic variation of applied magnetic strength. Interestingly, it is found that the domain wall structure exhibits transverse domain wall structure before the Walker breakdown field while the vortex/antivortex domain wall structure after the Walker breakdown field. The domain wall velocity increases as the applied field strength increases before the Walker breakdown field and decreases after the Walker breakdown field. The Walker breakdown field decreases as the width and the thickness of nanowires increases. We also analyzed the energy magnetization density system around the Walker breakdown field. It is revealed that the magnetostatic energy dominates of the energy system and the exchange energy tendency increases as the vortex/antivortex structures is formed in ferromagnetic nanowires.

Djuhana, D.; Manaf, A.; Sumarta, A.; Mardona, Kim, D.-H.

2014-03-01

247

Discrete Mathematics and Theoretical Computer Science AC, 2003, 2738 Some results for directed lattice walkers in a  

E-print Network

lattice walkers in a strip Yao-ban Chan and Anthony J. Guttmann Department of Mathematics and Statistics results for directed lattice walkers in a horizontal strip of finite width. Some cases with two walkers in a small width are solved exactly, as are a couple of cases with vicious walkers in a small width

Guttman, Tony

248

Casimir effect for curved boundaries in Robertson-Walker spacetime  

E-print Network

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 background of the Robertson-Walker spacetime with negative spatial curvature. 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 Dirichlet and Neumann scalars and for the electromagnetic field these forces are attractive for all separations.

A. A. Saharian; M. R. Setare

2010-06-14

249

On the Conformal forms of the Robertson-Walker metric  

E-print Network

All possible transformations from the Robertson-Walker metric to those conformal to the Lorentz-Minkowski form are derived. It is demonstrated that the commonly known family of transformations and associated conformal factors are not exhaustive and that there exists another relatively less well known family of transformations with a different conformal factor in the particular case that K = -1. Simplified conformal factors are derived for the special case of maximally-symmetric spacetimes. The full set of all possible cosmologically-compatible conformal forms is presented as a comprehensive table. A product of the analysis is the determination of the set-theoretical relationships between the maximally symmetric spacetimes, the Robertson-Walker spacetimes, and functionally more general spacetimes. The analysis is preceded by a short historical review of the application of conformal metrics to Cosmology.

M. Ibison

2007-04-20

250

Coarctation of the aorta associated with Dandy-Walker variant.  

PubMed

This article reports a rare case of coarctation of the aorta associated with Dandy-Walker variant in a 17-year-old girl. Differential diagnoses of coarctation of the aorta and Dandy-Walker variant are extensively discussed. In addition, standard surgical treatment of coarctation as well as new approaches such as endovascular stenting are described in detail to provide therapeutic insights into her management. Although surgical or endovascular repair of coarctation results in significant improvement of systemic hypertension and is associated with better survival, cardiovascular complications are still very common. Thus, long-term follow-up after repair is required, and high-quality imaging studies such as echocardiography, CT and MRI are warranted. PMID:24396258

Zhou, Li; Lui, George K; Shenoy, Rajesh; Taub, Cynthia C

2013-09-01

251

Coarctation of the aorta associated with Dandy-Walker variant  

PubMed Central

This article reports a rare case of coarctation of the aorta associated with DandyWalker variant in a 17-year-old girl. Differential diagnoses of coarctation of the aorta and DandyWalker variant are extensively discussed. In addition, standard surgical treatment of coarctation as well as new approaches such as endovascular stenting are described in detail to provide therapeutic insights into her management. Although surgical or endovascular repair of coarctation results in significant improvement of systemic hypertension and is associated with better survival, cardiovascular complications are still very common. Thus, long-term follow-up after repair is required, and high-quality imaging studies such as echocardiography, CT and MRI are warranted. PMID:24396258

Zhou, Li; Lui, George K.; Shenoy, Rajesh; Taub, Cynthia C.

2013-01-01

252

From classical chaos to decoherence in Robertson-Walker cosmology  

E-print Network

We analyse the relationship between classical chaos and particle creation in Robertson-Walker cosmological models with gravity coupled to a scalar field. Within our class of models chaos and particle production are seen to arise in the same cases. Particle production is viewed as the seed of decoherence, which both enables the quantum to classical transition, and ensures that the correspondence between the quantum and classically chaotic models will be valid

Fernando C. Lombardo; Mario Castagnino; Luca Bombelli

1998-06-25

253

The Enigmatic Young Object: Walker 90/V590 Monocerotis  

E-print Network

We assess the evolutionary status of the intriguing object Walker 90/V590 Mon, which is located about 20 arcminutes northwest of the Cone Nebula near the center of the open cluster NGC 2264. This object, according to its most recent optical spectral type determination (B7), which we confirmed, is at least 3 magnitudes too faint in V for the cluster distance, but it shows the classical signs of a young pre-main sequence object, such as highly variable Halpha emission, Mg II emission, IR excess, UV continuum, and optical variability. We analyzed a collection of archival and original data on Walker 90, covering 45 years including photometry, imaging, and spectroscopic data ranging from ultraviolet to near-infrared wavelengths. According to star formation processes, it is expected that, as this object clears its primordial surroundings, it should become optically brighter, show a weakening of its IR excess and present decreasing line emissions. This behavior is supported by our observations and analysis, but timescales are expected to be longer than the one observed here. Based on photometric data secured in 2007, we find Walker 90 at its brightest recorded optical magnitude. We document an evolution in spectral type over the past five decades (from A2/A3 to currently B7 and as early as B4), along with a decrease in the near-infrared K fluxes. From near-infrared images secured in 2004, Walker 90 appears as a point source placing an upper limit of 0.1 arcsec for its diameter. We conclude that many observational features are explained if W90 is a flared disk system, surrounded by an inclined optically thick accretion disk.

Mario R. Perez; Bruce McCollum; Mario E. van den Ancker; Michael D. Joner

2008-04-08

254

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

E-print Network

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

Ovidiu-Cristinel Stoica

2012-03-08

255

FriedmanRobertsonWalker Models with Late-Time Acceleration  

NASA Astrophysics Data System (ADS)

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

Abdussattar; Prajapati, S. R.

2011-02-01

256

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

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

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

257

1-bit walker recognition with distributed binary pyroelectric sensors  

Microsoft Academic Search

This paper presents a wireless compressive pyroelectric sensor system for walker recognition. The research aims to make wireless distributed pyroelectric sensors a low-cost, low-data-throughput alternative to the expensive infrared video sensors in behavioral biometric applications. The compressive measurements are achieved by using both (1) non-uniform sensor sampling structures and (2) random projection based sensing protocols. As a result, the gait

Xin Zhou; Qi Hao; Hu Fei

2010-01-01

258

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

259

Particle filter based feedback control of JAIST Active Robotic Walker  

Microsoft Academic Search

We present a new control scheme of JAIST Ac- tive Robotic Walker (JARoW) developed to provide potential users such as the elderly with sufficient ambulatory capability. Toward its practical use, we tackle JARoW's easy and reliable maneuverability by creating a natural user interface between a user and JARoW. Specifically, our focus is placed on how to realize the natural and

Takanori Ohnuma; Geunho Lee; Nak Young Chong

2011-01-01

260

Neurocutaneous melanosis with associated Dandy-Walker complex  

Microsoft Academic Search

Case reportThe 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

261

Terrain Interaction With The Quarter Scale Beam Walker  

NASA Astrophysics Data System (ADS)

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, R. S.; Spiessbach, Andrew J.

1990-03-01

262

Scaling Limit of Vicious Walkers, Schur Function, and Gaussian Random Matrix Ensemble  

E-print Network

We consider the diffusion scaling limit of the vicious walkers and derive the time-dependent spatial-distribution function of walkers. The dependence on initial configurations of walkers is generally described by using the symmetric polynomials called the Schur functions. In the special case in the scaling limit that all walkers are started from the origin, the probability density is simplified and it shows that the positions of walkers on the real axis at time one is identically distributed with the eigenvalues of random matrices in the Gaussian orthogonal ensemble. Since the diffusion scaling limit makes the vicious walkers converge to the nonintersecting Brownian motions in distribution, the present study will provide a new method to analyze intersection problems of Brownian motions in one-dimension.

M. Katori; H. Tanemura

2001-10-12

263

Cystic retrocerebellar malformations: unification of the Dandy-Walker complex and the Blake's pouch cyst.  

PubMed

Twenty-six cases of developmental retrocerebellar cyst (RCC) formation are studied with respect to determining the usefulness and anatomic relevance of separate terms currently in use, including Dandy-Walker complex, Dandy-Walker malformation, Dandy-Walker variant, mega-cisterna magna (MCM), and Blake's pouch cyst. An anatomic and embryological continuum between Dandy-Walker complex and Blake's pouch cyst is proposed. A method for the useful assessment of RCC is outlined. The patency or closure of the aqueduct is crucial to the evaluation and management of hydrocephalus associated with RCC formation. PMID:8414749

Strand, R D; Barnes, P D; Poussaint, T Y; Estroff, J A; Burrows, P E

1993-01-01

264

Rationality of Spectral Action for Robertson-Walker Metrics  

E-print Network

We use pseudodifferential calculus and heat kernel techniques to prove a conjecture by Chamseddine and Connes on rationality of the coefficients of the polynomials in the cosmic scale factor $a(t)$ and its higher derivatives, which describe the general terms $a_{2n}$ in the expansion of the spectral action for general Robertson-Walker metrics. We also compute the terms up to $a_{12}$ in the expansion of the spectral action by our method. As a byproduct, we verify that our computations agree with the terms up to $a_{10}$ that were previously computed by Chamseddine and Connes by a different method.

Farzad Fathizadeh; Asghar Ghorbanpour; Masoud Khalkhali

2014-07-22

265

Pilot Joe Walker with the X-1E  

NASA Technical Reports Server (NTRS)

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

1958-01-01

266

``Natural'' Vacua in Hyperbolic Friedmann-Robertson-Walker Spacetimes  

E-print Network

Recent evidence indicates that the Universe is open, i.e., spatially hyperbolic, longstanding theoretical preferences to the contrary notwithstanding. This makes it possible to select a vacuum state, Fock space, and particle definition for a quantized field, by requiring concordance with ordinary flat-spacetime theory at late times. The particle-number basis states thus identified span the physical state space of the field at all times. This construction is demonstrated here explicitly for a massive, minimally coupled, linear scalar field in an open, radiation-dominated Friedmann-Robertson-Walker spacetime.

Ian H. Redmount

1999-04-30

267

Science to Sustain Terminal Lakes: The Walker River Basin Study  

USGS Publications Warehouse

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

U.S. Geological Survey

2005-01-01

268

Quantum Cosmology from the Friedmann-Robertson-Walker-Lemaitre Spacetime  

E-print Network

The Friedmann-Robertson-Walker-Lemaitre metric tensor in matter fields presence in quantum context is studied. New quantization method for this cosmological model is proposed. Four elementary approaches are effectively jointed. The Dirac method for constrained systems is used, then the Fock space is built and the second quantization is carried out. Finally the diagonalization ansatz is proposed - combination of the Bogoliubov transformation and the Heisenberg equation of motion. As a result the Quantum Cosmology as the many-Universe system is formulated.

Glinka, L A

2006-01-01

269

Noncommutative corrections to the Robertson-Walker metric  

SciTech Connect

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

Fabi, S.; Harms, B.; Stern, A. [Department of Physics, University of Alabama, Tuscaloosa, Alabama 35487 (United States)

2008-09-15

270

Direct Line: (250) 714-0045 Lab Tel: (250) 714-0044 ...1 of 18 pages Mr. Mark Walker  

E-print Network

Direct Line: (250) 714-0045 Lab Tel: (250) 714-0044 ...1 of 18 pages Mr. Mark Walker Public Affairs Tracking For Survival, Proposal # 200311400 Dear Mr. Walker: I write in response to the NWPPC preliminary

271

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

E-print Network

370 P. L. WALKER,JR.,AND EMILERAATS Vol. 60 EFFECT OF GAS DIFFUSION IN GRAPHITIZED CARBON RODS ON THEIR GASIFICATION RATE WITH CARBON DIOXIDE'>' BYP. L. WALKER,JR.,AND EMILERAATS Department of Fuel Technology

272

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

Federal Register 2010, 2011, 2012, 2013

...Energy Regulatory Commission [Docket No. ER13-327-000] Porter-Walker LLC; Supplemental Notice That Initial Market-Based...supplemental notice in the above-referenced proceeding of Porter-Walker LLC's application for market-based rate...

2012-11-14

273

Talking about baby walkers: Insights about health education from the field  

Microsoft Academic Search

Objective To explore the perceptions and experiences of health visitors and parents of health education approaches to baby walker use.Design An exploratory focus group study to inform the development of an educational intervention to reduce baby walker use. Five groups were conducted. One group consisted solely of health visitors, one of antenatal parents and three of parents of children under

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

2003-01-01

274

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

Microsoft Academic Search

We study the differences between the processes of decoherence induced by chaotic and regular environments. For this we analyze a family of simple models that contain both regular and chaotic environments. In all cases the system of interest is a ``quantum walker,'' i.e., a quantum particle that can move on a lattice with a finite number of sites. The walker

Leonardo Ermann; Juan Pablo Paz; Marcos Saraceno

2006-01-01

275

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

National Technical Information Service (NTIS)

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. Evaporat...

K. K. Allander, T. J. Lopes

2009-01-01

276

STS-53 Commander Walker adjusts LES prior to JSC emergency egress training  

NASA Technical Reports Server (NTRS)

STS-53 Discovery, Orbiter Vehicle (OV) 103, Commander David M. Walker pulls at launch and entry suit (LES) neck ring and neck dam in an attempt to adjust it and/or loosen it. Walker appears uncomfortable and makes the adjustments in preparation for launch emergency egress bailout procedures in JSC's Mockup and Integration Laboratory (MAIL) Bldg 9NE.

1992-01-01

277

Off the Clock: Walker Evans and the Crisis of American Capital, 1933-38  

E-print Network

the Politics of Visual Circulation in Walker Evanss Cubathe Politics of Visual Circulation in Walker Evanss Cubapolitics, was in Evanss diaries: in 1933 Evans made an entry that delineated his attitude towards the revolution in Cuba (and,

May, Jessica Lee

2010-01-01

278

Influence of infant-walkers on motor development: Mimicking spastic diplegia?  

Microsoft Academic Search

We discuss two patients, who used an infant walker during the period in which they learned to walk. The influence on qualitative and quantitative motor development is illustrated in this report. A disharmonic and delayed motor development, contractures of the calf-muscles and motor development mimicking spastic diplegia are considered to be caused by the early use of infant walkers. As

Raoul H. H. Engelbert; Ron Van Empelen; Nienke D. Scheurer; Paul J. M. Helders; Onno Van Nieuwenhuizen

1999-01-01

279

, 20120153, published 22 April 20133682013Phil. Trans. R. Soc. B and Wayne S. Walker  

E-print Network

. Macedo, Michael T. Coe, Ruth DeFries, Maria Uriarte, Paulo M. Brando, Christopher Neill Land, Uriarte M, Brando PM, Neill C, Walker WS. 2013 Land-use-driven stream warming in southeastern AmazoniaFries2, Maria Uriarte2, Paulo M. Brando1,3, Christopher Neill4 and Wayne S. Walker1 1 Woods Hole Research

Uriarte, Maria

280

This article was downloaded by:[Walker, Andrew] On: 18 November 2007  

E-print Network

this negative portrayal of rural electoral culture. Drawing on ethnographic field work in northern Thailand://www.informaworld.com/smpp/title~content=t776095547 The rural constitution and the everyday politics of elections in Northern Thailand Andrew Walker Online Publication Date: 01 February 2008 To cite this Article: Walker, Andrew (2008) 'The rural

281

Hunting a Random Walker on a Low Dimensional Torus Yariv Yaari  

E-print Network

Hunting a Random Walker on a Low Dimensional Torus Yariv Yaari Abstract We will define a problem of dimension 2,3. 1 Hunting a Random Walker There are several natural variants of the hunting problem, here expected hunting time complexity, comparing it to a simple lower bound on the complexity for any algorithm

282

Neurobiology of Disease Brain and Eye Malformations Resembling WalkerWarburg  

E-print Network

Neurobiology of Disease Brain and Eye Malformations Resembling Walker­Warburg Syndrome Durbeej,1,2 Tobias Willer,1,2 Amy Turner,1,2 Steven A. Moore,3 and Kevin P. Campbell1,2,4,5 1Howard Hughes 52242 Walker­Warburg syndrome (WWS) is a severe congenital disease that is characterized by brain

Campbell, Kevin P.

283

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

284

Task-Space Control of Extensible Continuum Manipulators Apoorva Kapadia and Ian D. Walker  

E-print Network

for continuum robot hardware, To whom all correspondence should be addressed. A. Kapadia and I. D. WalkerTask-Space Control of Extensible Continuum Manipulators Apoorva Kapadia and Ian D. Walker Abstract and tentacle" robots. Development of model-based control algo- rithms for this new and emerging class of robots

285

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

Microsoft Academic Search

BACKGROUND: The advances in technology make possible the incorporation of sensors and actuators in rollators, building safer robots and extending the use of walkers to a more diverse population. This paper presents a new method for the extraction of navigation related components from upper-body force interaction data in walker assisted gait. A filtering architecture is designed to cancel: (i) the

Anselmo Frizera Neto; Juan A Gallego; Eduardo Rocon; Jos L Pons; Ramn Ceres

2010-01-01

286

A robotic walker for standing assistance with realtime estimation of a patient's load  

Microsoft Academic Search

This paper proposes a standing assistance control for our robotic walker system. Our developing assistance system is based on a walker which is a popular assistance device for an aged person in normal daily life and realizes a standing motion using its support pad which is actuated by novel assistance manipulator mechanisms with four parallel linkages. Our system assists a

Daisuke Chugo; Yusuke Morita; Sho Yokota; Yuki Sakaida; Kunikatsu Takase

2012-01-01

287

Augmented variable center of rotation in controlling a robotic walker to adapt user characteristics  

Microsoft Academic Search

This paper propose a new control algorithm for a robotic walker based on augmented variable center of rotation (COR) to adapt to user's controlling characteristics. The new CORs are taken from environment-based training. This is done by allowing the user to use the robotic walker from a start point to a goal point in a training environment and path following

Y. Hirata; K. Kosuge

2005-01-01

288

Dissemination of Walker 256 carcinoma cells to rat skeletal muscle  

SciTech Connect

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

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

1986-03-05

289

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

290

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

291

Third annual Walker Branch watershed research symposium: Programs and abstracts  

SciTech Connect

The methods and concepts of watershed research, originally applied in an experimental or monitoring mode to relatively small catchments, are increasingly being used at larger scales and for specific applied problems. Research at Oak Ridge National Laboratory, the Tennessee Valley Authority, the US Forest Service, and other agencies and institutions participating in this symposium reflects research over a broad range of spatial scales. These research projects address the basic atmospheric, geophysical, biogeochemical, and biological processes that regulate the responses of forested ecosystems to natural environmental variation and anthropogenic stresses. Regional and global issues addressed by presentations include emissions of carbon dioxide, methane, and other hydrocarbons; deposition of sulfate, nitrate, and mercury; land-use changes; biological diversity; droughts; and water quality. The Department of Energy`s local research site, Walker Branch Watershed, is a long-term ecosystem research project initiated on the Oak Ridge Reservation in 1967. Walker Branch provides a well-characterized site where many of these methods can be tested and applied.In addition, other large-scale experiments represented in this symposium include experiments on the effects of clearcutting and burning on forest structure and productivity associated with Coweeta Hydrologic Laboratory, and whole-tree ozone exposure chambers constructed by TVA and ORNL researchers

Not Available

1992-03-01

292

Third annual Walker Branch watershed research symposium: Programs and abstracts  

SciTech Connect

The methods and concepts of watershed research, originally applied in an experimental or monitoring mode to relatively small catchments, are increasingly being used at larger scales and for specific applied problems. Research at Oak Ridge National Laboratory, the Tennessee Valley Authority, the US Forest Service, and other agencies and institutions participating in this symposium reflects research over a broad range of spatial scales. These research projects address the basic atmospheric, geophysical, biogeochemical, and biological processes that regulate the responses of forested ecosystems to natural environmental variation and anthropogenic stresses. Regional and global issues addressed by presentations include emissions of carbon dioxide, methane, and other hydrocarbons; deposition of sulfate, nitrate, and mercury; land-use changes; biological diversity; droughts; and water quality. The Department of Energy's local research site, Walker Branch Watershed, is a long-term ecosystem research project initiated on the Oak Ridge Reservation in 1967. Walker Branch provides a well-characterized site where many of these methods can be tested and applied.In addition, other large-scale experiments represented in this symposium include experiments on the effects of clearcutting and burning on forest structure and productivity associated with Coweeta Hydrologic Laboratory, and whole-tree ozone exposure chambers constructed by TVA and ORNL researchers

Not Available

1992-03-01

293

Neuroimaging of Dandy-Walker malformation: new concepts.  

PubMed

Dandy-Walker malformation (DWM) is the most common human cerebellar malformation, characterized by hypoplasia of the cerebellar vermis, cystic dilation of the fourth ventricle, and an enlarged posterior fossa with upward displacement of the lateral sinuses, tentorium, and torcular. Although its pathogenesis is not completely understood, there are several genetic loci related to DWM as well as syndromic malformations and congenital infections. Dandy-Walker malformation is associated with other central nervous system abnormalities, including dysgenesis of corpus callosum, ectopic brain tissue, holoprosencephaly, and neural tube defects. Hydrocephalus plays an important role in the development of symptoms and neurological outcome in patients with DWM, and the aim of surgical treatment is usually the control of hydrocephalus and the posterior fossa cyst. Imaging modalities, especially magnetic resonance imaging, are crucial for the diagnosis of DWM and distinguishing this disorder from other cystic posterior fossa lesions. Persistent Blake's cyst is seen as a retrocerebellar fluid collection with cerebrospinal fluid signal intensity and a median line communication with the fourth ventricle, commonly associated with hydrocephalus. Mega cisterna magna presents as an extraaxial fluid collection posteroinferior to an intact cerebellum. Retrocerebellar arachnoid cysts frequently compress the cerebellar hemispheres and the fourth ventricle. Patients with DWM show an enlarged posterior fossa filled with a cystic structure that communicates freely with the fourth ventricle and hypoplastic vermis. Comprehension of hindbrain embryology is of utmost importance for understanding the cerebellar malformations, including DWM, and other related entities. PMID:24132069

Correa, Gustavo Gumz; Amaral, Lzaro Faria; Vedolin, Leonardo Modesti

2011-12-01

294

Maximum Distance Between the Leader and the Laggard for Three Brownian Walkers  

E-print Network

We consider three independent Brownian walkers moving on a line. The process terminates when the left-most walker (the `Leader') meets either of the other two walkers. For arbitrary values of the diffusion constants D_1 (the Leader), D_2 and D_3 of the three walkers, we compute the probability distribution P(m|y_2,y_3) of the maximum distance m between the Leader and the current right-most particle (the `Laggard') during the process, where y_2 and y_3 are the initial distances between the leader and the other two walkers. The result has, for large m, the form P(m|y_2,y_3) \\sim A(y_2,y_3) m^{-\\delta}, where \\delta = (2\\pi-\\theta)/(\\pi-\\theta) and \\theta = cos^{-1}(D_1/\\sqrt{(D_1+D_2)(D_1+D_3)}. The amplitude A(y_2,y_3) is also determined exactly.

Satya N. Majumdar; Alan J. Bray

2010-06-30

295

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

Federal Register 2010, 2011, 2012, 2013

...Requirements for Baby-Bouncers and Walker-Jumpers AGENCY: Consumer Product Safety...the requirements for baby-bouncers and walker-jumpers in regulations codified at 16...Requirements for Baby-Bouncers and Walker-Jumpers One CPSC regulation bans...

2012-09-05

296

SUBMITTED TO IEEE TRANS. ON AUTOMATIC CONTROL -REGULAR PAPER, DECEMBER 2001 1 Hybrid Zero Dynamics of Planar Biped Walkers  

E-print Network

of Planar Biped Walkers E.R. Westervelt , J.W. Grizzle+ , D.E. Koditschek Abstract-- Planar, underactuated, biped walkers form an important domain of applications for hybrid dynamical sys- tems. This paper constraints. The general theory developed in the paper is illustrated on a five link walker, consisting

Grizzle, Jessy W.

297

A. Eyre-Walker and P. D. Keightley Estimating the rate of adaptive molecular evolution in the presence of  

E-print Network

A. Eyre-Walker and P. D. Keightley Estimating the rate of adaptive molecular evolution developed a second approach to infer based on the method to infer the DFE of Eyre- Walker et al. (2006 is the likelihood function for the polymorphism data given the DFE, as given by equation (6) of Eyre-Walker et al

Eyre-Walker, Adam

298

doi:10.1016/j.gca.2003.08.007 The multifarious scientific career of Robert M. Walker  

E-print Network

doi:10.1016/j.gca.2003.08.007 The multifarious scientific career of Robert M. Walker THOMAS J sciences, Robert M. ("Bob") Walker. The symposium was attended by over a hundred of his colleagues for glorification of the person--rather, it is the work that counts. The organizers of the Walker Symposium

299

Design and Control of a Clutch for a Minimally-Actuated Biped Based on the Passive-Dynamic Simple Walker  

E-print Network

Walker by Arlis Reynolds SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING IN PARTIAL FULFILLMENT Based on the Passive-Dynamic Simple Walker by Arlis Reynolds Submitted to the Department of Mechanical is tested on a hip actuated simple 3D walker to evaluate the performance capabilities of clutched control

Tedrake, Russ

300

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

E-print Network

to the nucleus by multiple random walkers Ting Lu, Tongye Shen, Chenghang Zong, Jeff Hasty, and Peter G. Wolynes by multiple random walkers in compartment phosphorylation space Ting Lu* , Tongye Shen , Chenghang Zong , Jeff biased random walkers compete to reach their target in the nucleus yielding a signal. Here, the first

Hasty, Jeff

301

Vol. 60364 P. L. WALKER,JR.,AND EMILERAATS whether the swelling is of the predicted order of  

E-print Network

Vol. 60364 P. L. WALKER,JR.,AND EMILERAATS whether the swelling is of the predicted order. WALKER,JR.,AND EMILERAATS Department of Fuel Technology, The Pennsylvania State University, University with changes in the physical structure of the carbon. This work is an extension of the finding of Walker

302

A Review of Thermal Rectification Observations and Models in Solid N.A. Roberts, D.G. Walker  

E-print Network

.G. Walker Department of Mechanical Engineering, Vanderbilt University, Nashville, TN USA, 37325 Abstract problems [2]. Currently several mechanisms for Corresponding author Email address: greg.walker@vanderbilt.edu (D.G. Walker) Preprint submitted to Elsevier November 22, 2010 #12;0 5 10 15 20 25 30 35 40 1920 1930

Walker, D. Greg

303

From Vicious Walkers to TASEP. T.C. Dorlas, A.M. Povolotsky, V.B. Priezzhev  

E-print Network

From Vicious Walkers to TASEP. T.C. Dorlas, A.M. Povolotsky, V.B. Priezzhev August 7, 2008 Abstract and the vicious walkers model. We calculate the survival probability for this model and obtain the scaling we mention two of them. The first one is the vicious walkers (VW) model that has been introduced

Dorlas, Teunis C.

304

G R I N N E L L C O L L E G E Henry M. Walker  

E-print Network

G R I N N E L L C O L L E G E Henry M. Walker Samuel R and Marie-Louise Rosenthal Professor-269-4984fax walker@cs.grinnell.edu http://www.cs.grinnell.edu/~walker/ Revised Project Proposal I propose robots and to develop materials (handouts and laboratory exercises) for the use of robots in CSC 161

Walker, Henry MacKay

305

Optimizing DNA nanotechnology through coarse-grained modeling: a two-footed DNA walker.  

PubMed

DNA has enormous potential as a programmable material for creating artificial nanoscale structures and devices. For more complex systems, however, rational design and optimization can become difficult. We have recently proposed a coarse-grained model of DNA that captures the basic thermodynamic, structural, and mechanical changes associated with the fundamental process in much of DNA nanotechnology, the formation of duplexes from single strands. In this article, we demonstrate that the model can provide powerful insight into the operation of complex nanotechnological systems through a detailed investigation of a two-footed DNA walker that is designed to step along a reusable track, thereby offering the possibility of optimizing the design of such systems. We find that applying moderate tension to the track can have a large influence on the operation of the walker, providing a bias for stepping forward and helping the walker to recover from undesirable overstepped states. Further, we show that the process by which spent fuel detaches from the walker can have a significant impact on the rebinding of the walker to the track, strongly influencing walker efficiency and speed. Finally, using the results of the simulations, we propose a number of modifications to the walker to improve its operation. PMID:23414564

Ouldridge, Thomas E; Hoare, Rollo L; Louis, Ard A; Doye, Jonathan P K; Bath, Jonathan; Turberfield, Andrew J

2013-03-26

306

Higgs effective potential in a perturbed Robertson-Walker background  

E-print Network

We calculate the one-loop effective potential of a scalar field in a Robertson-Walker background with scalar metric perturbations. A complete set of orthonormal solutions of the perturbed equations is obtained by using the adiabatic approximation for comoving observers. After analyzing the problem of renormalization in inhomogeneous backgrounds, we get the explicit contribution of metric perturbations to the effective potential. We apply these results to the Standard Model Higgs effective potential and evaluate the effects of metric perturbations on the Higgs vacuum expectation value. Space-time variations are found, which are proportional to the gravitational slip parameter, with a typical amplitude of the order of $\\Delta\\phi/\\phi\\simeq 10^{-11}$ on cosmological scales. We also discuss possible astrophysical signatures in the Solar System and in the Milky Way that could open new possibilities to explore the symmetry breaking sector of the electroweak interactions.

Antonio L. Maroto; Francisco Prada

2014-09-29

307

Maximal Distance Travelled by N Vicious Walkers Till Their Survival  

NASA Astrophysics Data System (ADS)

We consider $N$ Brownian particles moving on a line starting from initial positions ${\\bf{u}}\\equiv \\{u_1,u_2,\\dots u_N\\}$ such that $0walker till $t_s$. For general $N$ particles with identical diffusion constants $D$, we show that the probability distribution $p_N(m|{\\bf u})$ of the global maximum $m_N$, has a power law tail $p_i(m|{\\bf{u}}) \\sim {N^2B_N\\mathcal{F}_{N}({\\bf u})}/{m^{\

Kundu, Anupam; Majumdar, Satya N.; Schehr, Grgory

2014-10-01

308

Pauli-Fierz Gravitons on Friedmann-Robertson-Walker Background  

E-print Network

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

Luca Grisa; Lorenzo Sorbo

2009-05-21

309

On Quantum Mechanics in Friedmann-Robertson-Walker Universe  

E-print Network

It is shown that only in the space-times admitting a 1+3-foliation by flat Cauchy hypesurfaces (i.e., in the Bianchi I type space-times the isotropic version of which the spatially flat Friedmann-Robertson-Walker space-times are) the canonical quantization of geodesic motion and quantum-mechanics obtained as an asymptotics of the quantum theory of scalar field lead to the same canonical commutation relations (CCR). Otherwise, the field-theoretical approach leads to a deformation of CCR (particularly, operators of coordinates do not commute), and the Principle of Correspondence is broken in a sense. Thus, the spatially flat cosmology is distinguished intrinsically in the quantum theory.

E. A. Tagirov

2000-11-03

310

Number of Common Sites Visited by N Random Walkers  

E-print Network

We compute analytically the mean number of common sites, W_N(t), visited by N independent random walkers each of length t and all starting at the origin at t=0 in d dimensions. We show that in the (N-d) plane, there are three distinct regimes for the asymptotic large t growth of W_N(t). These three regimes are separated by two critical lines d=2 and d=d_c(N)=2N/(N-1) in the (N-d) plane. For dd_c(N), W_N(t) approaches a constant as t\\to \\infty. Exactly at the critical dimensions there are logaritmic corrections: for d=2, we get W_N(t)\\sim t/[\\ln t]^N, while for d=d_c(N), W_N(t)\\sim \\ln t for large t. Our analytical predictions are verified in numerical simulations.

Satya N. Majumdar; Mikhail V. Tamm

2012-06-27

311

Friedmann-Robertson-Walker like cosmologies with spherical symmetry  

E-print Network

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 $p_c=\\gamma \\rho_c$. 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 FRW models.

Mauricio Cataldo; Fernanda Arostica; Sebastian Bahamonde

2013-08-15

312

Gravitational waves propagating into Friedmann--Robertson--Walker universes  

E-print Network

We consider space-times with two isometries which represent gravitational waves with distinct wavefronts which propagate into exact Friedmann-Robertson-Walker (FRW) universes. The geometry of possible wavefronts is analysed in detail in all three types of FRW models. In the spatially flat and open universes, the wavefronts can be planar or cylindrical; in the closed case they are toroidal. Exact solutions are given which describe gravitational waves propagating into the FRW universes with a fluid with a stiff equation of state. It is shown that the plane-fronted waves may include impulsive or step (shock) components, while the cylindrical waves in the spatially flat and open universes and the toroidal waves in closed universes may contain steps. In general, wavefronts may exist which have an arbitrary finite degree of smoothness. In all cases, the waves are backscattered. The head-on collision of such waves is also briefly mentioned.

Jiri Bicak; Jerry B. Griffiths

1996-10-18

313

Effective Space Quantization in Friedman-Robertson-Walker Models  

E-print Network

Quantum--mechanical operators corresponding to canonical momentum and position of a point--like particle, which follow from the quantum field theory in the general Riemannian space-time, satisfy generally to a deformation of the canonical commutation relations with $c^{-2}$ as the parameter of deformation. For operators of the quasi-Cartesian coordinates in the closed and open Friedman--Robertson--Walker models, the deformation reproduces the spatial part of the well--known Snyder formula for quantization of the Minkowsky space-time. The spatially-flat models are distinguished apart by that the deformation is reduced exactly to the standard canonical commutation relations, which correlates remarkably with the fact of the observed flatness of the Universe. Conditions are briefly discussed for which the deformation could have cosmological manifestations. Key words: quantum mechanics, cosmology, quantized space.

E. A. Tagirov

2003-12-16

314

Clustering Determines Who Survives for Competing Brownian and Lvy 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 Lvy 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; Hernndez-Garcia, Emilio; Lpez, Cristbal

2013-06-01

315

Random Walker Ranking for NCAA Division I-A Football  

E-print Network

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

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

2003-01-01

316

Higgs effective potential in a perturbed Robertson-Walker background  

E-print Network

We calculate the one-loop effective potential of a scalar field in a Robertson-Walker background with scalar metric perturbations. A complete set of orthonormal solutions of the perturbed equations is obtained by using the adiabatic approximation for comoving observers. After analyzing the problem of renormalization in inhomogeneous backgrounds, we get the explicit contribution of metric perturbations to the effective potential. We apply these results to the Standard Model Higgs effective potential and evaluate the effects of metric perturbations on the Higgs vacuum expectation value. Space-time variations are found, which are proportional to the gravitational slip parameter, with a typical amplitude of the order of $\\Delta\\phi/\\phi\\simeq 10^{-11}$ on cosmological scales. We also discuss possible astrophysical signatures in the Solar System and in the Milky Way that could open new possibilities to explore the symmetry breaking sector of the electroweak interactions.

Maroto, Antonio L

2014-01-01

317

Clustering determines who survives for competing Brownian and Lvy walkers.  

PubMed

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 Lvy 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. PMID:23829760

Heinsalu, Els; Hernndez-Garcia, Emilio; Lpez, Cristbal

2013-06-21

318

Walker diffusion method for calculation of transport properties of composite materials  

SciTech Connect

The morphology of a multiphase microstructure greatly influences the macroscopic transport properties of the composite material. These properties are shown to be related to the diffusion coefficient of a random (nonbiased) walker. The proper diffusion rules are found by considering an isomorphic image of the microstructure in which distinct populations of walkers correspond to the phase domains, with the walker density of a population proportional to the transport coefficient of the corresponding domain. To demonstrate the method, it is applied to disordered two-phase percolating composites. {copyright} {ital 1999} {ital The American Physical Society}

DeW. Van Siclen, C. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho 83415 (United States)] [Idaho National Engineering and Environmental Laboratory, Idaho Falls, Idaho 83415 (United States)

1999-03-01

319

Vacuum quantum effect for curved boundaries in static Robertson--Walker spacetime  

E-print Network

The energy-momentum tensor for a massless conformally coupled scalar field in the region between two curved boundaries in $k=-1$ static Robertson--Walker spacetime is investigated. We assume that the scalar field satisfies the Dirichlet boundary condition on the boundaries. $k=-1$ Robertson--Walker space is conformally related to the Rindler space, as a result we can obtain vacuum expectation values of energy-momentum tensor for conformally invariant field in Robertson--Walker space from the corresponding Rindler counterpart by the conformal transformation.

M R Setare; J Sadeghi

2009-07-17

320

Casimir Effect for the Robin Surfaces in Static Robertson-Walker Space-Time  

NASA Astrophysics Data System (ADS)

We investigate the energy-momentum tensor for a massless conformally coupled scalar field in the region between two curved surfaces in k = -1 static Robertson-Walker space-time. We assume that the scalar field satisfies the Robin boundary condition on the surfaces. Robertson-Walker space-time space is conformally related to Rindler space; as a result we can obtain vacuum expectation values of the energy-momentum tensor for a conformally invariant field in Robertson-Walker space-time space from the corresponding Rindler counterpart by the conformal transformation.

Setare, Mohammad R.; Dehghani, M.

321

Friedmann Robertson Walker models with Conformally Coupled Massive Scalar Fields are Non-integrable  

E-print Network

In this work we use a recently developed nonintegrability theorem of Morales and Ramis to prove that the Friedmann Robertson Walker cosmological model with a conformally coupled massive scalar field is nonintegrable.

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

2006-11-22

322

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

E-print Network

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

Xin-Bing Huang

2005-01-26

323

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

PubMed

The genus Luxiaria Walker and its allied genus Calletaera Warren in China, including 16 species in all, are reviewed. Five new species are described: C. obvia sp. nov., C. acuticornuta sp. nov., C. rotundicornuta sp. nov., C. dentata sp. nov., C. trigonoprocessus sp. nov. The species L. acutaria (Snellen, 1877) and L. tephrosaria (Moore, 1868) are newly recorded for China. Two new combinations are established: C. obliquata (Moore, 1888) comb. nov. and C. consimilaria (Leech, 1897) comb. nov. Four new synonyms are established: Eutoea Walker, 1860 (= Bithiodes Warren, 1894 syn. nov.); Calletaera Warren, 1895 (=Bithiodes Warren, 1899 syn. nov.), based on the fixation of nominal type Acidalia inexactata Walker, 1861, for the genus name Bithiodes Warren, 1894; L. emphatica Prout, 1925 (= L. costinota Inoue, 1978 syn. nov.); C. subexpressa (Walker, 1861) (= C. digrammata Wehrli, 1925 syn. nov.). Diagnoses for all Chinese species are provided. Illustrations of external features and genitalia are presented. PMID:25284646

Jiang, Nan; Xue, Dayong; Han, Hongxiang

2014-01-01

324

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, Ren; Park, Jeong-Hyuck

2007-06-29

325

On the Geometric Reduction of Controlled Three-Dimensional Bipedal Robotic Walkers  

Microsoft Academic Search

The purpose of this paper is to apply methods from geometric mechanics to the analysis and control of bipedal robotic walkers.\\u000a We begin by introducing a generalization of Routhian reduction, functional Routhian Reduction, which allows for the conserved quantities to be functions of the cyclic variables rather than constants.\\u000a Since bipedal robotic walkers are naturally modeled as hybrid systems, which

Aaron D. Ames; Robert D. Gregg; Eric D. B. Wendel; Shankar Sastry

326

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

Microsoft Academic Search

Based on estimates from the U.S. Consumer Product Safety Commission (CPSC), there were about 25,000 baby walker-related injuries treated annually in U.S. hospital emergency departments during the early 1990s. This amounted to about 8 injuries for every 1000 baby walkers in use. Most injuries resulted from falls down stairs. After CPSC initiated a regulatory proceeding in 1994, the CPSC staff

Gregory B. Rodgers; Elizabeth W. Leland

2008-01-01

327

Geomorphic Analysis Supporting Restoration of the Walker River, Nevada  

NASA Astrophysics Data System (ADS)

Agricultural water diversions have degraded the Walker River, Nevada, and have led to a reduction of water level at its terminus, Walker Lake. The geomorphic response of the river to water reallocation is an important issue associated with restoration of the system. To address this issue, we performed a geomorphic assessment of the portions of the river passing through the two main agricultural valleys in the watershed, Smith and Mason Valleys, Nevada. The project involved field data collection, analysis of remotely sensed data, and numerical modeling. Fieldwork focused primarily on characterizing bed and bank sediment grain size distributions and on delineating geomorphically similar reaches. The remote sensing analysis used LiDAR and air photograph mosaics from 1938, 1950, 1996, 1999, and 2006 to quantify historic changes in the active channel geometry and to identify banks that represent potential sediment sources or sinks. Polygons representing in-channel features (here defined as the scoured region between vegetation lines) were delineated by hand on each photograph. Channel centerlines were then derived from this data set and were used to identify locations of active channel movement by measuring either direct centerline offsets or local sinuosity increase rates. Both active bar area and channel migration were focused on reaches near the head of each agricultural valley, where slope decreases as the channel emerges from an upstream bedrock-controlled canyon. These same reaches also experienced large increases in width during the 1997 flood of record. The gage record shows that attenuation of this flood was most pronounced in the lower of the two agricultural valleys, Mason Valley. Surprisingly little attenuation occurred in the upstream Smith Valley, despite the relatively low relief of the valley floor, which consists primarily of Pleistocene lake deposits. The major difference between the two valleys is that the meander belt through Smith Valley is incised into the ancient lake bed, probably constraining flood flow to a much narrower region than in Mason Valley. In support of a reach scale morphodynamic model for the system, we estimated reach-average sediment exchange flux between eroding cut banks and new point bars. The estimates were derived from the overall rate of sinuosity increase for each subreach, rather than from simple lateral offset measurements which are sensitive to misalignment in the historic aerial photographs. Because bars are generally composed of coarser sediment than is typical for eroding cut banks, this exchange is probably associated with net storage of gravel in the floodplain. For several reaches in the dataset, lateral storage computed in this manner represents a significant fraction of bed material transport capacity.

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

2012-12-01

328

Dynamics of unvisited sites in presence of mutually repulsive random walkers  

E-print Network

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

Pratap K. Das; Subinay Dasgupta; Parongama Sen

2007-03-06

329

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

330

Third annual Walker Branch Watershed research symposium. Program and abstracts  

SciTech Connect

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

Not Available

1992-03-01

331

On the gravitational instability of a set of random walkers  

NASA Astrophysics Data System (ADS)

We consider the time-dependent distribution, c(r,t), of N > > 1 identical point-like random walkers which interact via a Newtonian potential in a d-dimensional unbounded Euclidean space. This distribution is usually studied by means of the Smoluchowski-Poisson equation in which the self-interaction of the Brownian particles is incorporated as a mean-field dragging force. In this letter we find the exact solution of this equation in one dimension for any normalizable and symmetric initial condition. This solution is found by exploiting the similarity of the equation for u(r,t), the mass inside a hypersphere of radius r, and Burgers's equation. We prove that the one-dimensional system is stable under arbitrary symmetric perturbations and always converges to the well-known stationary state. An exact scaling solution representing monotonous evaporation in two dimensions, c(r,t) = C(r2/t)/t, is also studied and we show that it only exists for N < Nc, where Nc is the number of particles corresponding to the unstable stationary state.

Acedo, L.

2006-03-01

332

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

333

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

334

Glucagon degradation by a product of the Walker 256 carcinosarcoma  

SciTech Connect

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

Zepp, E.A.

1986-03-05

335

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

PubMed

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

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

2014-01-01

336

The Fire-Walker's High: Affect and Physiological Responses in an Extreme Collective Ritual  

PubMed Central

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

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

2014-01-01

337

Prenatal diagnosis of Dandy-Walker malformation: report of a case.  

PubMed

Dandy-Walker malformation is one of the major causes of congenital hydrocephalus. We report on a case that was diagnosed by sonography in a fetus at 34 weeks' gestation. The diagnosis was confirmed by postnatal computed tomographic (CT) brain scan and magnetic resonance imaging (MRI). The prenatal sonographic findings were a large posterior fossa in communication with the fourth ventricle, a small and splayed cerebellar hemisphere and marked degrees of ventriculomegaly. The postnatal CT scan images were similar to the prenatal sonography. The hypoplasia of the cerebellar vermis and the associated hypogenesis of the corpus callosum can only be clearly delineated by MRI. Dandy-Walker malformation is one form of the Dandy-Walker complex and cystic malformations of the posterior fossa. It should be differentiated from Dandy-Walker variant, or mega-cisterna magna, and arachnoid cyst. Dandy-Walker complex may be associated with chromosomal, intracranial and extracranial abnormalities. Early in utero detection is useful for detailed evaluation of associated anomalies. Obstetric management depends on gestational age, karyotype abnormality and associated intracranial and extracranial anomalies. In the present report, the infant presented no progressive ventriculomegaly and no surgery was required. The infant developed normally. PMID:7633204

Chen, F P; Chu, K K

1994-01-01

338

Reduced Walker 256 carcinosarcoma growth in vasopressin-deficient Brattleboro rats.  

PubMed

The growth pattern of carcinosarcoma Walker 256 was studied in rats with different levels of vasopressin in the blood. The Brattleboro rats are unable to synthesize vasopressin in a consequence of deletion in the coding gene. Hybrids from crossbreeding of the mutant Brattleboro and normal WAG rats inherit the one intact vasopressin gene and hold nearly normal hormone level. It was found that non-strain-specific carcinosarcoma Walker 256 intensively grows in WAG rats and their offsprings from crossbreeding with Brattleboro rats, and tumor development is equally terminated in them by death. Carcinosarcoma grows less intensely in Brattleboro rats; the tumor nodes increased only within the first 2weeks, after which, the tumor began to decrease and eventually disappeared. Infusion of exogenous vasopressin to Brattleboro rats intensifies a tumor growth in the first 2weeks after the inoculation of Walker 256 cells; however, it does not prevent a following regression and resorption of tumors. PMID:20559788

Khegay, Igor I; Popova, Nelli A; Ivanova, Ludmila N

2010-12-01

339

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

340

Safety Committee notes from March 1, 2006 Attending: Thea Smith, Hollis Lundeen, Faith Cole< Randy Walker, Brian Parker, Lori  

E-print Network

groups, so that their will be training on all year. Tsunami issues: Concern was brought up over the lack of warning for employees should a tsunami warning be issued. Walker told that HMSC has crafted an evacuation. Walker was asked to set up a fire extinguish training. Hearing protection was discussed and OSU

341

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

Federal Register 2010, 2011, 2012, 2013

...Intent To Prepare an Environmental Impact Statement for the Walker Ridge Wind Project, Lake and Colusa Counties, CA Agency...Draft EIS. ADDRESSES: You may submit comments related to the Walker Ridge Wind Project by any of the following methods: Web...

2010-08-13

342

[Ultrastructural changes in endothelial cells of blood capillaries of the Walker 256 carcinosarcoma while treated with melatonin].  

PubMed

In Wistar rats with transplanted Walker 256 carcinosarcoma a use of melatonin as monoagent causes changes in intracellular organization of endothelial cells: reduced volume density of mitochondria, granular cytoplasmic network, micropinocytic vesicles, reduced the number density of free and attached ribosomes, which leads to increased apoptosis of tumor cells of Walker 256 carcinosarcoma. PMID:24919267

Ovsianko, E V; Pustovetova, M G; Samsonova, E N; Ovsianko, Ia U; Fedina, R G; Kulishenko, A O; Vinogradov, A S

2014-01-01

343

New Dynamic Models for Planar Extensible Continuum Robot Manipulators Enver Tatlicioglu, Ian D. Walker, and Darren M. Dawson  

E-print Network

. In [17], Jones and Walker presented a kinematic model for a general class of continuum robots which hasNew Dynamic Models for Planar Extensible Continuum Robot Manipulators Enver Tatlicioglu, Ian D. Walker, and Darren M. Dawson Abstract: In this paper, the dynamic model for planar continuum manipulators

344

Bearing witness to the trauma of slavery in Kara Walker's videos: Testimony, Eight Possible Beginnings, and I was transported  

Microsoft Academic Search

This essay shows that Kara Walker creates in her film and video work a repetitive traumatic site that surrounds, involves, and challenges the viewer to witness, acknowledge, and remember the individual and transgenerational trauma of slavery and contemporary racism in the United States, contributing to cultural remembrance and forcing the viewer to bear witness to her topsy-turvy world. Walker represents

Vivien Green Fryd

2010-01-01

345

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.

2014-09-01

346

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

USGS Publications Warehouse

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

Nilsen, T.H.

1980-01-01

347

Giant occipital meningocele in an 8-year-old child with DandyWalker malformation  

Microsoft Academic Search

IntroductionThe possibility of an association between DandyWalker malformation and occipital meningocele is well-known. However, just\\u000a an overall number of about 40 cases have been previously reported. Giant occipital meningocele has been described only in\\u000a three newborns. Incidence, pathology, clinical presentation, and proper management of this association are still poorly defined.\\u000a \\u000a \\u000a \\u000a \\u000a Report of the caseAn 8-year-old boy with DandyWalker malformation and

Giuseppe Talamonti; Marco Picano; Alberto Debernardi; Moreno Bolzon; Mario Teruzzi; Giuseppe DAliberti

2011-01-01

348

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

349

Evapotranspiration from the Lower Walker River Basin, West-Central Nevada, Water Years 2005-07. Scientific Investigations Report 2009-5079.  

National Technical Information Service (NTIS)

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 f...

J. L. Smith, K. K. Allander, M. J. Johnson

2009-01-01

350

A Unidirectional DNA Walker Moving Autonomously Along a Track** Peng Yin, Hao Yan*, Xiaoju G. Daniell, Andrew J. Turberfield*, John H. Reif*  

E-print Network

A Unidirectional DNA Walker Moving Autonomously Along a Track** Peng Yin, Hao Yan*, Xiaoju G. Various schemes of autonomous DNA walker devices based on DNA cleavage and ligation have been explored report the construction of a non-autonomous DNA biped walker device[19] and autonomous DNA tweezers.[20

Reif, John H.

351

Random Discrete Structures, ed. D. Aldous and R. Pemantle, Springer, New York, 1996, pp. 185--198. How Fast and Where Does a Random Walker  

E-print Network

--198. How Fast and Where Does a Random Walker Move on a Random Tree? By Russell Lyons Abstract. The oldest. A random walker starts at the root of the tree and chooses among the edges incident to the root at random, walking to the adjacent vertex. Then the walker again chooses among the incident edges including the one

Lyons, Russell

352

arXiv:0712.3838v2[gr-qc]3Mar2008 General Transformation Formulas for Fermi-Walker  

E-print Network

arXiv:0712.3838v2[gr-qc]3Mar2008 General Transformation Formulas for Fermi-Walker Coordinates David of Taylor expansions, from arbitrary coordinates to Fermi-Walker coordinates in tubular neighborhoods are given. KEY WORDS: Fermi-Walker coordinates, Fermi coordinates PACS numbers: 04.20.Cv, 04.20.-q 1

353

arXiv:0812.0255v1[cond-mat.stat-mech]1Dec2008 From Vicious Walkers to TASEP.  

E-print Network

arXiv:0812.0255v1[cond-mat.stat-mech]1Dec2008 From Vicious Walkers to TASEP. T.C. Dorlas1 , A December 1, 2008 Abstract We propose a model of semi-vicious walkers, which interpolates be- tween the totally asymmetric simple exclusion process and the vicious walkers model, having the two as limiting

Dorlas, Teunis C.

354

1997 Oxford University Press44084415 Nucleic Acids Research, 1997, Vol. 25, No. 21 Sequence walkers: a graphical method to display how  

E-print Network

walkers: a graphical method to display how binding proteins interact with DNA or RNA sequences Thomas D by a sequence logo. These sequence `walkers' can be stepped along raw sequence data to visually search for binding sites. Many walkers, for the same or different proteins, can be simultaneously placed next

Schneider, Thomas D.

355

PA Central Support Group 3 Self Propelled Walker Many patients with neuromuscular conditions do not possess sufficient upper body strength to  

E-print Network

PA Central Support Group 3 ­ Self Propelled Walker Overview Many patients with neuromuscular would greatly benefit from a walker which is self-propelled to reduce the amount of energy required from the user. Objective The objective is to design and build a self-propelling walker which can be used

Demirel, Melik C.

356

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

PubMed Central

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

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

2009-01-01

357

Ocean-Atmosphere Interaction in the Making of the Walker Circulation and Equatorial Cold Tongue  

Microsoft Academic Search

The climate over the equatorial Pacific displays a pronounced asymmetry in the zonal direction that is characterized by the Walker circulation in the atmosphere and the cold tongue in the ocean. An intermediate coupled ocean-atmosphere model is used to investigate the driving force and the ocean-atmosphere interaction mechanism for the generation of the zonal asymmetry. In the far eastern Pacific,

Shang-Ping Xie

1998-01-01

358

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

E-print Network

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

Robillard, Martin

359

Sleep-Dependent Memory Processing Matthew P. Walker, PhD  

E-print Network

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

Walker, Matthew P.

360

Physical Activity Patterns among Walkers and Compliance with Public Health Recommendations.  

ERIC Educational Resources Information Center

Assessed data from the 1998 Behavioral Risk Factor Surveillance System to determine the prevalence of walking for physical activity and the proportions of walkers who met current public health physical activity recommendations. Results indicated that in 1998, approximately 38.6 percent of U.S. adults walked for physical activity. Less than 40

Rafferty, Ann P.; Reeves, Mathew J.; McGee, Harry B.; Pivarnik, James M.

2002-01-01

361

The semi classical cosmology approximation for a Friedman Robertson Walker geometry coupled to a field  

E-print Network

The semi classical cosmology approximation for a Friedman Robertson Walker geometry coupled to a field is considered. A power series of the field with coefficients that depend on the radius of the geometry is proposed, and the equations for the coefficients are solved.

Jose L. Martinez-Morales

2011-04-08

362

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

ERIC Educational Resources Information Center

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

Matunda, Robert Stephen Mokaya

2009-01-01

363

Knee design for a bipedal walking robot based on a passive-dynamic walker  

E-print Network

Passive-dynamic walkers are a class of robots that can walk down a ramp stably without actuators or control due to the mechanical dynamics of the robot. Using a passive-dynamic design as the basis for a powered robot helps ...

Baines, Andrew Griffin

2005-01-01

364

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

365

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

ERIC Educational Resources Information Center

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

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

2005-01-01

366

The Merger of the Schwarzschild metric and the Robertson-Walker metric  

E-print Network

The Schwarzschild metric giving the space time due to a spherically symmetric object is derived in the background of the Robertson Walker metric. In other words the two metrics are merged. It is found that under certain conditions the merger is at a distance less than the radius of the spherically symmetric object, thus not separating the object from the rest of the universe.

Bethmini Senevirathne; Nalin de Silva

2008-12-19

367

Applications of Elliptic and Theta Functions to Friedmann-Robertson-Lemaitre-Walker Cosmology with Cosmological Constant  

E-print Network

Elliptic functions are known to appear in many problems, applied and theoretical. However, a lesser known application is in the study of exact solutions to Einstein's gravitational field equations in a Friedmann-Robertson-Lemaitre-Walker (FRLW) cosmology. We will show explicitly how Jacobi and Weierstrass elliptic functions arise in this context, and will additionally show connections with theta functions.

Jennie D'Ambroise

2009-08-18

368

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

ERIC Educational Resources Information Center

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

Zirkel, Perry A.

2012-01-01

369

Simulation of the Single- and Double-Slit Experiments with Quantum Walkers  

E-print Network

We employ the broken-link model to create a barrier with slits in a two-dimensional lattice. The diffraction and interference patterns of the probability distribution of quantum walkers passing through the slits are analyzed. Simulations were performed using the main types of coins, and display diffraction and interference patterns that depend on the choice of coins.

Amanda C. Oliveira; Renato Portugal; Raul Donangelo

2007-06-21

370

Reunion of random walkers with a long range interaction: applications to polymers and quantum mechanics  

E-print Network

We use renormalization group to calculate the reunion and survival exponents of a set of random walkers interacting with a long range $1/r^2$ and a short range interaction. These exponents are used to study the binding-unbinding transition of polymers and the behavior of several quantum problems.

Sutapa Mukherji; Somendra M. Bhattacharjee

2001-01-10

371

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

E-print Network

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

Liudmila Joukovskaya

2008-07-14

372

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

PubMed

In order to investigate stress responses of horses in walkers with and without electricity, 12 horses were trained during 3 weeks in a horse walker with and without the use of electricity (3.7 kV). To evaluate the stress response, cortisol levels in the blood were measured, the heart rate was monitored using the Polar system and the behaviour was evaluated. Neither the cortisol levels nor the heart rates showed any relevant statistically significant difference between horses moved in the horse walker with or without the use of electricity. The highest cortisol levels and heart rates were recorded during the first week (habituation period). A significant difference could be observed regarding spontaneous compartment changes: while this happened mainly during the first week and before the first use of electricity, no horses changed compartments in the periods when electricity was used and thereafter. The results of this study indicate that the use of electricity in the horse walker does not seem to cause significant detectable stress in the horses. PMID:24686816

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

2014-04-01

373

STS-30 Commander Walker and Pilot Grabe during JSC preflight press conference  

NASA Technical Reports Server (NTRS)

During preflight press conference, STS-30 Commander David M. Walker (right) and Pilot Ronald J. Grabe ponder questions from the news media. 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

374

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

375

Zero moment point-measurements from a human walker wearing robot feet as shoes  

Microsoft Academic Search

The anthropomorphic biped robot Bip is equipped with sensors for measuring the ground\\/feet forces in order to lo- calize the center of pressure (CoP) and zero moment point (ZMP). This paper focuses on experimental results regarding the evolu- tion of the ground contact forces, obtained from a human walker wearing the robot feet as shoes. First, one determines the influence

Philippe Sardain; Guy Bessonnet

2004-01-01

376

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

Microsoft Academic Search

In her teens, Mary Edwards Walker already wore the bloomer outfit and began to campaign for reforming the unhygienic clothing of women. Assertively, she attended medical school and earned her M.D. degree. Due to prejudice, her practice did not flourish and she moved to Washington to offer her medical services to the Union as the Civil War began. Rebuffed by

Allen D. Spiegel; Peter B. Suskind

1996-01-01

377

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

Microsoft Academic Search

We append forward walking to a diffusion Monte Carlo algorithm which maintains a fixed number of walkers. This removes the importance sampling bias of expectation values of operators which do not commute with the Hamiltonian. We demonstrate the effectiveness of this approach by employing three importance sampling functions for the hydrogen atom ground state, two very crude. We estimate moments

Ivana Bos; Stuart M. Rothstein

2004-01-01

378

Precipitation Change and Soil Leaching: Field Results and Simulations from Walker Branch Watershed, Tennessee  

Microsoft Academic Search

To investigate the potential effects of changing precipitation on a deciduous forest ecosystem, an experiment was established on Walker Branch Watershed, Tennessee that modified the amount of throughfall at -33%, ambient (no change), and +33% using a system of rain gutters and sprinklers. We hypothesized that the drier treatments would cause: 1) disproportionate changes in soil water flux, 2) increased

D. W. Johnson; P. J. Hanson; D. E. Todd; R. B. Susfalk; C. F. Trettin

1998-01-01

379

Collaborative Music to Motivate Mathematics Learning Rodney T. Walker, Mark Guzdial  

E-print Network

Collaborative Music to Motivate Mathematics Learning Rodney T. Walker, Mark Guzdial Georgia the last decade, the importance of motivation in learning math has been one of the most important issues with both motivation and applicability in a child's life. Recently, it has been shown that issues

Guzdial, Mark

380

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

ERIC Educational Resources Information Center

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

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

2010-01-01

381

Anthropogenic changes in the Walker Circulation and their impact on the extra-  

E-print Network

tropospheric meridional wind in the CMIP3 models. The dominant response is a wave number five pattern similar models show significant deviations from the Walker circulation as diagnosed from the ERA Interim and NCEP) and Joseph et al. (2004) indicate the change of the zonal mean state as the dominant cause of the change

Selten, Frank

382

Psychophysical Scaling of Sonification Mappings Bruce N. Walker Gregory Kramer David M. Lane  

E-print Network

Psychology Dept. Clarity Psychology Dept. Rice University 310 NW Brynwood Lane Rice University 6100 Main StPsychophysical Scaling of Sonification Mappings Bruce N. Walker Gregory Kramer David M. Lane.edu lane@rice.edu ABSTRACT We determined preferred data-to-display mappings by asking experiment

383

In the Morgue: Censorship, Taste and the Politics of Visual Circulation in Walker Evans's Cuba Portfolio  

Microsoft Academic Search

Walker Evans arrived in Havana in 1933, commissioned to produce a portfolio of original photographs for Carleton Beals's polemical The Crime of Cuba and immediately proceeded to the city's newspaper archives. There he made photographic copies of a significant number of images of the remains of the victims of dictator Gerardo Machado's terrorist tactics, many of which had been banned

Jordan Bear

2007-01-01

384

Dandy-Walker malformation with postaxial polydactly: a new case of Pierquin syndrome.  

PubMed

The combination of Dandy-Walker malformation, other central nervous system anomalies, and postaxial polydactyly has been reported previously in two pairs of siblings. We propose the name 'Pierquin syndrome' for this combination and we report a new patient with this disorder. PMID:23324646

Passalacqua, Cristbal A; Villegas, Victor P; Aracena, Mariana I; Mellado, Cecilia X

2013-04-01

385

A large-scale throughfall manipulation experiment on Walker Branch Watershed  

Microsoft Academic Search

A throughfall displacement experiment is being performed in a mixed-age upland-oak forest on the upper slopes of Walker Branch Watershed in eastern Tennessee to investigate the effects of decreased and increased rainfall on individual species and ecosystem processes at the spatial scale of forest stands. Approximately 25% of the throughfall on the ``dry`` plot will be collected in polyethylene troughs

R. S. Turner; P. J. Hanson; M. A. Huston; C. T. Jr. Garten; P. J. Mulholland

1992-01-01

386

A large-scale throughfall manipulation experiment on Walker Branch Watershed  

Microsoft Academic Search

A throughfall displacement experiment is being performed in a mixed-age upland-oak forest on the upper slopes of Walker Branch Watershed in eastern Tennessee to investigate the effects of decreased and increased rainfall on individual species and ecosystem processes at the spatial scale of forest stands. Approximately 25% of the throughfall on the dry'' plot will be collected in polyethylene troughs

R. S. Turner; P. J. Hanson; M. A. Huston; C. T. Jr. Garten; P. J. Mulholland

1992-01-01

387

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

E-print Network

's sensitivity by a factor of ~2 over previously published techniques [2]. One improvement is a new #12;parameterSurveying The TeV Sky With Milagro G. P. Walker for the Milagro Collaboration Los Alamos National highly variable or are extended. Milagro is such a TeV detector and has performed the deepest survey

California at Santa Cruz, University of

388

DNA Mismatch Repair and Synonymous Codon Evolution in Mammals Adam Eyre-Walker  

E-print Network

DNA Mismatch Repair and Synonymous Codon Evolution in Mammals Adam Eyre-Walker Institute of Cell to predict the expected relationship between the rate of substitution and G+C content at silent sites. It was found that the silent-substitution rate should decline with increasing G+C content over most of the G

Eyre-Walker, Adam

389

Problems with Parsimony in Sequences of Biased Base Composition Adam Eyre-Walker  

E-print Network

Problems with Parsimony in Sequences of Biased Base Composition Adam Eyre-Walker Centre- simony. Key words: Parsimony -- G + C content -- Base composition -- Substitution pattern -- Mutation. The cases are of the sort gen- erally encountered in the inference of substitution and mutation patterns (e.g

Eyre-Walker, Adam

390

Quantum nature of the hydrogen bond Xin-Zheng Li, Brent Walker, and Angelos Michaelides1  

E-print Network

Quantum nature of the hydrogen bond Xin-Zheng Li, Brent Walker, and Angelos Michaelides1 London (received for review November 9, 2010) Hydrogen bonds are weak, generally intermolecular bonds, which hold of hydrogen bonds and consequently the structure of hydrogen bonded sys- tems is still absent. Here, we report

Weeks, Eric R.

391

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

E-print Network

and interpretation. Section 2 gives a general overview of empirical studies in discourse and describes an empiricalEmpirical Studies in Discourse Marilyn A. Walker \\Lambda & Johanna D. Moore y 1. Introduction Computationaltheories of discourse are concerned with the context�based interpretation or generation of discourse

Moore, Johanna D.

392

JAIST Robotic Walker control based on a two-layered Kalman filter  

Microsoft Academic Search

This paper presents a new control scheme of JAIST Active Robotic Walker (JARoW) developed to provide elderly people with sufficient ambulatory capability. Toward its practical use, our focus is placed on how to allow easier and reliable maneuverability by creating a natural user interface. Specifically, our challenge lies in providing a well-functioning controller by detecting what the user wants to

Geunho Lee; Eui-Jung Jung; Takanori Ohnuma; Nak Young Chong; Byung-Ju Yi

2011-01-01

393

The wheel control of a robotic walker for standing and walking assistance with stability  

Microsoft Academic Search

This paper proposes a robotic walker system with standing and walking assistance device. Our system focuses on domestic use for aged person who needs nursing in their daily life. Our key ideas are two topics. The first topic is combination of standing assistance function and walking assistance function. In previous works, many assistance devices are specialized in only ldquostanding-up operationrdquo

D. Chugo; W. Mastuoka; Songmin Jia; K. Takase

2008-01-01

394

Large Haptic Topographic Maps: MarsView and the Proxy Graph Algorithm Sean P. Walker  

E-print Network

Large Haptic Topographic Maps: MarsView and the Proxy Graph Algorithm Sean P. Walker Computer-mail:spw@cs.stanford.edu e-mail:jks@robotics.stanford.edu Figure 1: MarsView in action. a need for highly interactive means

Salisbury, Kenneth

395

SUPPORTING ONLINE MATERIAL Efficient bipedal robots based on passive-dynamic walkers  

E-print Network

SUPPORTING ONLINE MATERIAL for Efficient bipedal robots based on passive-dynamic walkers Steven H. Materials and Methods. Details about the robots' construction and control. 2. An analogy. A description of the parallels (in content, not in significance) between first powered flight and these robots. In addition we

Collins, Steven H.

396

Parallel Robot Control Using Speculative Computation Deirdre L. Hamilton, Ian D. Walker, and John K. Bennett  

E-print Network

Parallel Robot Control Using Speculative Computation Deirdre L. Hamilton, Ian D. Walker, and John K Due to the coupling in the dynamics equations, coarse­grain parallelism of robot control algorithms to the problem. 1 Introduction As robots are used for more difficult tasks, control requirements increase

Bennett, John K.

397

Activity recognition from the interactions between an assistive robotic walker and human users  

Microsoft Academic Search

Detection of individuals' intention from a sequence of actions is an open and complex problem. In this paper we present a smart walker as mobility aid which can interpret the users' behaviour patterns to recognize their intentions and consequently act as an intelligent assistant. The result of the experiments performed in this paper demonstrates the potential of dynamic bayesian networks

Mitesh Patel; Jaime Valls Miro; Gamini Dissanayake

2011-01-01

398

A moving control of a robotic walker for standing, walking and seating assistance  

Microsoft Academic Search

This paper proposes a robotic walker system with standing, walking and seating assistance function. Our system focuses on domestic use for aged person who needs nursing in their daily life. Our key ideas are two topics. The first topic is combination of standing assistance function and walking assistance function. In previous works, many assistance devices are specialized in only ldquostanding-up

D. Chugo; T. Asawa; T. Kitamura; Songmin Jia; K. Takase

2009-01-01

399

A motion control of a robotic walker for continuous assistance during standing, walking and seating operation  

Microsoft Academic Search

This paper proposes a robotic walker system with standing, walking and seating assistance function. Our system focuses on domestic use for aged person who needs nursing in their daily life. Our key ideas are two topics. The first topic is combination of standing assistance function and walking assistance function. In previous works, many assistance devices are specialized in only standing-up

Daisuke Chugo; Tai Asawa; Takuya Kitamura; Songmin Jia; Kunikatsu Takase

2009-01-01

400

A novel human-machine interface for guiding: The NeoASAS smart walker  

Microsoft Academic Search

In an aging society it is extremely important to develop devices, which can support and aid the elderly in their daily life. This demands tools that extend independent living and promote improved health. In this work it is proposed a new interface approach integrated into a walker. This interface is based on a force sensor and it is intended to

Maria M. Martins; Anselmo Frizera-Neto; Eloy Urendes; Cristina dos Santos; Ramon Ceres; Teodiano Bastos-Filho

2012-01-01

401

IN-HAPTICS: Interactive Navigation using Haptics Richard D. Walker IV  

E-print Network

IN-HAPTICS: Interactive Navigation using Haptics Richard D. Walker IV University of California § Boston University ABSTRACT We present a computational framework and experimental platform for robot the robot through an environment cluttered with obstacles. We present a case study in which the operator res

Dupont, Pierre

402

Oxygen consumption and ammonia accumulation in the hypolimnion of Walker Lake, Nevada  

Microsoft Academic Search

Walker Lake (area = 140 km2, Zmean = 19.3 m) is a large, terminal lake in western Nevada. As a result of anthropogenic desiccation, the lake has decreased in volume by 75% since the 1880s. The hypolimnion of the lake, now too small to meet the oxygen demand exerted by decaying matter, rapidly goes anoxic after thermal stratification. Field and

Marc W. Beutel

2001-01-01

403

Responses to Gizzard Shad Recovery following Selective Treatment in Walker County Lake, Alabama, 1996-1999  

Microsoft Academic Search

Gizzard shad Dorosoma cepedianum is an important prey fish that is capable of influencing both the upper and lower trophic levels in aquatic systems. Contrary to our predictions, during the 4 years after a selective reduction of gizzard shad in Walker County State Fishing Lake (WCL), Alabama, the sport fish population structure did not decline as gizzard shad abundance rebounded.

Brian J. Irwin; Dennis R. DeVries; Gene W. Kim

2003-01-01

404

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

E-print Network

ACTIVITIES TO ATTRACT HIGH SCHOOL GIRLS TO COMPUTER SCIENCE Susan H. Rodger Ellen L. Walker for high school girls. These hands-on activities and interactive talks, presented mostly by female faculty at the highest levels. Al- though women and men study computer science in high school in equal numbers

Rodger, Susan H.

405

Production of cachexia mediators by Walker 256 cells from ascitic tumors.  

PubMed

In neoplasic cachexia, chemical mediators seem to act as initiators or perpetuators of this process. Walker 256 cells, whose metabolic properties have so far been little studied with respect to cancer cachexia, are used as a model for the study of this syndrome. The main objective of this research was to pinpoint the substances secreted by these cells that may contribute to the progression of the cachectic state. Since inflammatory mediators seem to be involved in the manifestation of this syndrome, the in vitro production of nitric oxide (NO), cytokines (tumor necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6)), and prostaglandin E2 (PGE2) was evaluated in Walker 256 cells isolated from ascitic tumors. After 4 or 5 h, a significant increase in NO production was observed (2.55 +/- 1.56 and 4.05 +/- 1.99 nmol NO per 10(7) cells, respectively). When isolated from a 6-day-old tumor, a significantly lower production of IL-6 and higher production of TNF-alpha than in cells from a 4-day-old tumor were observed, indicating a relationship between the production of cytokines and the time of tumor development after implantation. Considerable production of PGE(2) by Walker 256 cells isolated from the 6-day-old tumor was also observed. Polyamines were also determined in Walker 256 cells. Levels of putrescine, spermidine, and spermine did not show significant differences in tumors developed during 4 or 6 days. Direct evidence of the release of proinflammatory cytokines and PGE2 by Walker 256 cells suggests that these mediators can drive the cachectic syndrome in the host, the effect being dependent on tumor development time. PMID:18646274

Rebeca, Rosilene; Bracht, Lvia; Noleto, Guilhermina Rodrigues; Martinez, Glaucia Regina; Cadena, Silvia Maria Suter Correia; Carnieri, Eva Gunilla Skare; Rocha, Maria Eliane Merlin; de Oliveira, Maria Benigna Martinelli

2008-08-01

406

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 ~N30W. 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 ~N30E 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

407

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

USGS Publications Warehouse

The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and adjacent basins are filled or poorly developed. To the south, the basin sizes are moderate, 2545km 1510 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300 and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ?85-100km wide, where the basins are elongated E-W to ENE, small (?15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ?5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

Jayko, Angela S.; Bursik, Marcus

2012-01-01

408

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

409

Coexistance of cerebral sinovenous thrombosis and Dandy Walker malformation in newborn.  

PubMed

Cerebral sinovenous thrombosis in neonatal period may cause neurological impairment, epilepsy, and lead to stroke. It is caused primarily by coagulopathy of numerous reasons, occasionally perinatal asphyxia, traumatic delivery and hyperhomocysteinemia. Dandy-Walker malformation is characterized by agenesis or hypoplasia of the cerebellar vermis, cystic dilatation of the fourth ventricle, and enlargement of the posterior fossa. Dandy-Walker malformation, variant, and mega cisterna magna represent a spectrum of developmental anomalies. Insults to developing cerebellar hemispheres and the fourth ventricle are believed to be the cause of malformation. Our patient was born from noncomplicated pregnancy, noncomplicated nontraumatic vaginal delivery at term, excellent Apgar scores, without peculiarities in clinical status. She was brest-fed by the 42nd hour of life when she had rightsided seizures during sleep that repeated for five times in next 24 hours. Brain Ultrasound (US) revealed clot in left lateral ventricle, slight dilatation of left ventricle, both sided periventricular echodensity, ischemia, slight enlargement of forth ventricle and a bit smaller cerebellum. There was no visible flow through left transverse, superior sagittal and straight sinus. Magnetic Resonance (MRI) confirmed the finding and showed thrombosis of left and right transverse venous sinuses and confluence of sinuses. Electroencephalogram (EEG) showed leftsided focal changes. The newborn was treated with phenobarbiton for 8 days and had no convulsions during that period. All coagulation parameters, homocistein, lipoproteins (a) and D-dimers were normal. There were no mutations on FV R506Q, PT 20210A, MTHFR 677C/T. No antiphospholipides were found. Heart US showed no structural anomalies. No other patology or risk factors were present at the time. Before discharge, US showed hydrocephalus. Flow in affected sinuses was visible with color Doppler. MRI showed recanalization of affected sinuses, also hydrocephalus and presentation of Dandy Walker On EEG there was borderline finding. Due to progression of hydrocephalus ventriculo-peritoneal shunt was placed. In age of 1 year EEG was slower for age but without focus. Neurological development was normal for age. The question is whether this child had intrauterine insult and inception of Dandy Walker with further postnatal progress of thrombosis and evolution to full picture of Dandy Walker with hydrocephalus OR thrombosis that led to development of hydrocephalus and Dandy Walker malformation in this child were accidental coexistance. PMID:21648352

Gveri?-Ahmetasevi?, Snjezana; Coli?, Ana; Gveri?, Tugomir; Gasparovi?, Vesna Elvedi; Pavlisa, Goran; Ozreti?, David

2011-01-01

410

The Dirac Equation and the Normalization of its Solutions in a Closed Friedmann-Robertson-Walker Universe  

E-print Network

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

Felix Finster; Moritz Reintjes

2009-01-06

411

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

SciTech Connect

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

Ermann, Leonardo [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (C1429BNP), Buenos Aires (Argentina); Departamento de Fisica, FCEyN, UBA, Pabellon 1 Ciudad Universitaria, 1428 Buenos Aires (Argentina); Paz, Juan Pablo [Departamento de Fisica, FCEyN, UBA, Pabellon 1 Ciudad Universitaria, 1428 Buenos Aires (Argentina); Theoretical Division, LANL, MSB213, Los Alamos, New Mexico 87545 (United States); Saraceno, Marcos [Departamento de Fisica, Comision Nacional de Energia Atomica, Avenida del Libertador 8250 (C1429BNP), Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, Universidad Nacional de San Martin, Alem 3901 (B1653HIM), Villa Ballester (Argentina)

2006-01-15

412

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

E-print Network

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

R J Wiltshire

2003-02-12

413

Multi-walker discrete time quantum walks on arbitrary graphs, their properties, and their photonic implementation  

E-print Network

Quantum walks have emerged as an interesting alternative to the usual circuit model for quantum computing. While still universal for quantum computing, the quantum walk model has very different physical requirements, which lends itself more naturally to some physical implementations, such as linear optics. Numerous authors have considered walks with one or two walkers, on one dimensional graphs, and several experimental demonstrations have been performed. In this paper we discuss generalizing the model of discrete time quantum walks to the case of an arbitrary number of walkers acting on arbitrary graph structures. We present a formalism which allows for analysis of such situations, and several example scenarios for how our techniques can be applied. We consider the most important features of quantum walks -- measurement, distinguishability, characterization, and the distinction between classical and quantum interference. We also discuss the potential for physical implementation in the context of linear optics, which is of relevance to present day experiments.

Peter P. Rohde; Andreas Schreiber; Martin Stefanak; Igor Jex; Christine Silberhorn

2010-06-29

414

Relativistic Einstein-Podolsky-Rosen Correlations in curved spacetime via Fermi-Walker Transport  

E-print Network

We present a geometric description to study the relativistic EPR correlations in curved spacetime background given by the application of the Fermi-Walker transport in the relativistic EPR states and we show that its result has the same effect as the applications of successive infinitesimal Lorentz boosts in the relativistic EPR states. We also show that the expression for the Bell inequality due to the Fermi-Walker transport is equivalent to the expression demonstrated by Terashima and Ueda \\cite{TU2}, where the degree of violation of the Bell inequality is dependent of the angle of the Wigner rotation. This geometrical approach to study the relativistic EPR correlations is a promissing formulation to investigate the EPR correlations in the general relativity background.

Knut Bakke; Alexandre M. de M. Carvalho; Claudio Furtado

2009-02-13

415

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

E-print Network

We study the wave propagator for a Friedmann - Robertson - Walker background space-time, which is singular at time t=0. Using a spherical means formulation for the solution of the wave equation that is due to Klainerman and Sarnak, we derive three properties of solutions. the first is sharp time decay properties, using ideas of Fritz John. the second is that the wave equation in Friedmann - Robertson - Walker space-time does not satisfy the sharp Huygens property. The third is that the initial value problem for a class of data posed at the tingular time is well defined. Since the wave equation is reversible, this represents a class of data which propagates information smoothly from the past to the future passing through the space-time singularity.

Bilal Abbasi; Walter Craig

2014-04-29

416

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

USGS Publications Warehouse

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

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

1999-01-01

417

Decoherence induced by a chaotic environment: A quantum walker with a complex coin  

E-print Network

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

Leonardo Ermann; Juan Pablo Paz; Marcos Saraceno

2005-10-05

418

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

PubMed

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

da Silva, Airton R; Sup, Frank

2013-06-01

419

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

420

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

PubMed Central

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

K?v?lc?m, Yigit; Izci, Filiz; Semiz, Umit Basar

2014-01-01

421

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. PMID:24302956

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

2013-01-01

422

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

PubMed Central

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

Stovall, Joyce M.; Venkatesh, Ramachandran

1988-01-01

423

Tumor cells expressing the herpes simplex virus-thymidine kinase gene in the treatment of Walker 256 meningeal neoplasia in rats.  

PubMed

A promising strategy in the treatment of neoplastic meningitis involves the use of herpes simplex virus-thymidine kinase (HSV-tk)-modified cells. In these experiments the authors used cells expressing HSV-tk to treat meningeal carcinomatosis in the rat Walker 256 model. Intrathecal injection of 2 x 10(5) Walker cells resulted in a median survival time of 15 days. Up to 80% of animals implanted with HSV-tk-modified Walker cells (Walker-tk+) and treated with ganciclovir showed long-term survival (120 days or more), whereas the remaining animals died from tumor growth between 37 and 44 days after implantation. Tumor cells from an animal in which the treatment failed were cultured in vitro and were shown to be still sensitive to ganciclovir. However, continuous ganciclovir administration for 6 weeks rather than 2 weeks did not improve survival. Histopathological studies confirmed leptomeningeal infiltration in the untreated Walker or Walker-tk+ animals. Walker-tk+ cells were mixed with Walker cells in 1:1, 10:1, or 50:1 ratios, respectively, and implanted intrathecally; the animals were treated with ganciclovir. All groups of treated animals had long-term survivors, with 40% of the rats in the 10:1 and 50:1 groups demonstrating long-term survival and absence of microscopic tumors in the brain or spinal cord. Similarly, murine fibroblast HSV-tk virus-producer cells improved survival. Walker-tk+ cells were better than fibroblast-producer cells in improving the survival of animals with Walker tumors at low (1:1) but not at high (10:1) effector-to-target cell ratios. Repeated intrathecal administration of Walker-tk+ cells resulted in inhibition of established Walker tumors. The authors conclude that Walker-tk+ cells are at least as effective as murine virus-producer cells and could be used in the treatment of meningeal neoplasia. PMID:8592228

Vrionis, F D; Wu, J K; Qi, P; Cano, W G; Cherington, V

1996-02-01

424

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

425

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

E-print Network

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

J. M. Hoff da Silva; S. H. Pereira

2014-01-14

426

Asymptotic behavior of a relativistic diffusion in Robertson-Walker space-times  

E-print Network

We determine the long-time asymptotic behavior of a relativistic diffusion taking values in the unitary tangent bundle of a Robertson-Walker space-time. We prove in particular that when approaching the explosion time of the diffusion, its projection on the base manifold almost surely converges to a random point of the causal boundary and we also describe the behavior of the tangent vector in the neighborhood of this limiting point.

Jrgen Angst

2014-05-01

427

The Robertson-Walker Metric in a Pseudo-Complex General Relativity  

E-print Network

We investigate the consequences of the pseudo-complex General Relativity within a pseudo-complexified Roberston-Walker metric. A contribution to the energy-momentum tensor arises, which corresponds to a dark energy and may change with the radius of the universe, i.e., time. Only when the Hubble function $H$ does not change in time, the solution is consistent with a constant $\\Lambda$.

Peter O. Hess; Leila Maghlaoui; Walter Greiner

2010-01-28

428

On Lie Point Symmetries of Einstein's equations for the Friedmann-Roberstson-Walker Cosmology  

E-print Network

We study the Lie point symmetries of Einstein's equations for the Friedmann-Roberstson-Walker Cosmology. They form either a two - dimensional or a three - dimensional solvable group depending on the form of the self interacting potential. Using the invariants of the group we reduce the second order system of differential equations into a first order system. Writing the action in terms of the proper time we study the point symmetries and the variational symmetries of the resulting equations.

Paschalis G. Paschali; Georgios C. Chrysostomou

2009-10-05

429

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

E-print Network

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

Martina Brisudova; William H. Kinney

2000-06-07

430

Quantum evolution of scalar fields in Robertson-Walker space-time  

E-print Network

We study the $\\lambda \\phi^4$ field theory in a flat Robertson-Walker space-time using the functional Sch\\"odinger picture. We introduce a simple Gaussian approximation to analyze the time evolution of pure states and we establish the renormalizability of the approximation. We also show that the energy-momentum tensor in this approximation is finite once we consider the usual mass and coupling constant renormalizations.

O. J. P. Eboli; H. C. Reis

1995-10-10

431

The Walker Branch throughfall displacement experiment: An overview, field performance data, and initial growth responses  

Microsoft Academic Search

At Walker Branch Watershed a group of interdisciplinary scientists are conducting the Throughfall Displacement Experiment, a stand-level manipulation experiment that provides the appropriate environment for mechanistic studies of ecosystem and plant-level responses to changing precipitation inputs to an upland oak forest. Soil water is being manipulated by a gravity-driven transfer of one third of the throughfall precipitation from a {open_quotes}dry{close_quotes}

P. J. Hanson; D. E. Todd; K. M. Harter

1995-01-01

432

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

E-print Network

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

Ion I. Cotaescu

2007-08-06

433

A review of the Oriental genus Phycus Walker (Diptera: Therevidae) with descriptions of new species  

Microsoft Academic Search

Seven Oriental species of Phycus Walker are recognized. Two species groups: the atripes species-group and the brunneus species-group are established. The atripes species-group seems paraphyletic and contains five rarely collected species: Phycus angustifrons, sp. nov. (Thailand), Ph. atripes Brunetti, 1920 (Nepal, NE India, and SW China), Ph. hauseri, sp. nov. (Sri Lanka), Ph. minutus, sp. nov. (Sri Lanka), and Ph.

Leif Lyneborg

2003-01-01

434

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

Microsoft Academic Search

The relative importance of north-south migrations of the intertropical convergence zone (ITCZ) versus El Nio-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that north-south ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability

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

2011-01-01

435

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

PubMed

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

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

2014-01-01

436

41-D crewmembers Resnik and Walker prepare experiments in training for flight  

NASA Technical Reports Server (NTRS)

Astronaut Judith A. Resnik, mission specialist, and Charles D. Walker, payload specialist for 41-D, prepare for some scheduled intravehicular activity involving the continuous flow electrophoresis systems (CFES) experiment. In the background are stowage lockers and a CFES trainer - part of the shuttle one-G trainer at JSC (35755,35757); Resnik works with a sample connected to the CFE experiment during training session (35756,35758).

1984-01-01

437

The surface walker: a hemispherical mobile robot with rolling contact constraints  

Microsoft Academic Search

In this paper, we propose a new example of non-holonomic mobile robot, which we call the surface walker. This robot is composed of a hemisphere-shaped shell and a 2-d.o.f. mass-control device (pendulum) inside it, and undergoes the rolling contact constraint between the hemispherical surface of the robot and the ground. Unlike a lot of non-holonomic robots which have ever been

Masato Ishikawa; Yoshinori Kobayashi; Ryouhei Kitayoshi; Toshiharu Sugie

2009-01-01

438

Locomotion and Navigation of a Planar Walker Based on Binary Actuation  

Microsoft Academic Search

Locomotion and navigation of a surface walking\\/climbing robot - Planar Walker, based on a novel planar 8-bar mechanism are studied. The robot moves on a surface through decoupled transverse gaits and turning gaits with finite lengths and finite rotation angles. Motions of the gaits are modeled using planar rigid motion group SE(2). Three point-to- point navigation methods are developed for

I-ming Chen; Song Huat Yeo

2002-01-01

439

Robust spinal neuroinflammation mediates mechanical allodynia in Walker 256 induced bone cancer rats  

PubMed Central

It has been reported that remarkable and sustained activation of astrocytes and/or microglia occurs in cancer induced pain (CIP), which is different from neuropathic and inflammatory pain. The present study was designed to investigate the role of spinal Toll-like receptor 4 (TLR4) induced glial neuroinflammation in cancer induced pain using a modified rat model of bone cancer. The rat model of CIP consisted of unilateral intra-tibial injection with Walker 256 mammary gland carcinoma. Nine days after Walker 256 inoculation, a robust activation of both astrocytes and microglia in bilateral spinal dorsal horn was observed together with significant bilateral mechanical allodynia. This neuroinflammation was characterized by enhanced immunostaining of both glial fibrillary acidic protein (GFAP, astrocyte marker) and OX-42 (microglia marker), and an elevated level of IL-1?, IL-6 and TNF-? mRNA. I.t. administration of fluorocitrate (an inhibitor of glial metabolism, 1?nmol) or minocycline (an inhibitor of microglia, 100??g) has significant anti-allodynic effects on day 12 after Walker 256 inoculation. Naloxone (a nonstereoselective TLR4 signaling blocker, 60??g, i.t.) also significantly alleviated mechanical allodynia and simultaneously blocked the increased inflammatory cytokine mRNA. The results suggested that spinal TLR4 might play an important role in the sustained glial activation that critically contributed to the robust and sustained spinal neuroinflammation in CIP. This result could potentially help clinicians and researchers to better understand the mechanism of complicated cancer pain. PMID:22607655

2012-01-01

440

Robust spinal neuroinflammation mediates mechanical allodynia in Walker 256 induced bone cancer rats.  

PubMed

It has been reported that remarkable and sustained activation of astrocytes and/or microglia occurs in cancer induced pain (CIP), which is different from neuropathic and inflammatory pain. The present study was designed to investigate the role of spinal Toll-like receptor 4 (TLR4) induced glial neuroinflammation in cancer induced pain using a modified rat model of bone cancer. The rat model of CIP consisted of unilateral intra-tibial injection with Walker 256 mammary gland carcinoma. Nine days after Walker 256 inoculation, a robust activation of both astrocytes and microglia in bilateral spinal dorsal horn was observed together with significant bilateral mechanical allodynia. This neuroinflammation was characterized by enhanced immunostaining of both glial fibrillary acidic protein (GFAP, astrocyte marker) and OX-42 (microglia marker), and an elevated level of IL-1?, IL-6 and TNF-? mRNA. I.t. administration of fluorocitrate (an inhibitor of glial metabolism, 1 nmol) or minocycline (an inhibitor of microglia, 100 ?g) has significant anti-allodynic effects on day 12 after Walker 256 inoculation. Naloxone (a nonstereoselective TLR4 signaling blocker, 60 ?g, i.t.) also significantly alleviated mechanical allodynia and simultaneously blocked the increased inflammatory cytokine mRNA. The results suggested that spinal TLR4 might play an important role in the sustained glial activation that critically contributed to the robust and sustained spinal neuroinflammation in CIP. This result could potentially help clinicians and researchers to better understand the mechanism of complicated cancer pain. PMID:22607655

Mao-Ying, Qi-Liang; Wang, Xiao-Wei; Yang, Chang-Jiang; Li, Xiu; Mi, Wen-Li; Wu, Gen-Cheng; Wang, Yan-Qing

2012-01-01

441

Active immunotherapy of Walker-256 carcinosarcoma by tumor-infiltrating lymphocytes associated with photodynamic therapy  

NASA Astrophysics Data System (ADS)

Experiments were performed on five batches of Wistar inbred rats with Walker-256 carcinosarcoma receiving as sole treatment photodynamic therapy (PDT), tumor-infiltrating lymphocytes (TIL), or associated therapy (PDT + TIL - A; PDT + TIL - B). The control batch (HBSS) consisted of animals with untreated Walker-256 tumors. The results were as follows: the sole treatment (PDT, TIL) gave survival rates between 41.4 and 52.9%, the cure rates ranging from 13.8 to 38.2%. The `combined' therapy in multiple doses increased significantly (92.8%) the survival rate of tumor bearing rats as well as the highest incidence of complete tumor regression (82.1%). Cell-mediated immunity test values in batches III and IV exposed to multiple doses of PDT + TIL showed higher values as compared to the values noticed in batches I - II and the control batch V, performed at 10 and 21 days post-treatment. Summing up, this work demonstrates that `combined' photodynamic therapy with immunotherapy with TIL stimulates cell-mediated antitumoral activity, increases survival rates, and reduces incidence of Walker-256 carcinosarcoma in the rat model.

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

1995-01-01

442

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

SciTech Connect

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

Croyle, W.A.; Rosenbaum, S.E. [California Regional Water Quality Control Board, Sacramento, CA (United States)

1996-11-01

443

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

444

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

445

Rashba-induced chirality switching of domain walls and suppression of the Walker breakdown  

NASA Astrophysics Data System (ADS)

We investigate the current-induced motion of ferromagnetic domain walls in the presence of a Rashba spin-orbit interaction of the itinerant electrons. We show how a Rashba interaction can stabilize the domain wall motion, such that the Walker breakdown is shifted to larger current densities. The Rashba spin-orbit interaction creates a fieldlike contribution to the spin torque, which breaks the symmetry of the system and modifies the internal structure of the domain wall. Moreover, it can induce an additional switching of the chirality of the domain wall for sufficiently strong Rashba interactions. This allows one to choose the desired chirality by choosing the direction of the applied spin-polarized current. Both the suppression of the Walker breakdown and the chirality switching affect the domain wall velocity significantly. This is even more pronounced for short current pulses, where an additional domain wall drift in either positive or negative direction appears after the pulse ends. By this, we can steer the final position of the domain wall. This mechanism may help to overcome the current limitations of the domain wall motion due to the Walker breakdown which occurs for rather low current densities in systems without a Rashba spin-orbit interaction.

Stier, Martin; Creutzburg, Marcus; Thorwart, Michael

2014-07-01

446

Walker 256/S carcinosarcoma causes osteoporosis-like changes through ectopical secretion of luteinizing hormone-releasing hormone.  

PubMed

We have shown that Walker 256/S mammary carcinoma caused osteoporosis-like changes in young female rats, accompanied by low serum estradiol and hypercalciuria without changes in the serum levels of calcium, phosphorus, and parathyroid hormone-related peptide. In this study, we investigated the cause of bone loss after Walker 256/S inoculation into female 6-week-old Wistar Imamichi rats, focusing on the sex hormone balance in the host animal. Walker 256/S-bearing rats showed characteristic osteoporosis, with a significant increase in spleen weight and a significant decrease in uterine weight by 14 days after s.c. tumor inoculation. In the in vitro bone marrow culture, mineralized nodule formation ability decreased according to the time after tumor inoculation, and tartrate-resistant acid phosphatase-positive multinucleated cell formation increased at 7 days after tumor inoculation, but it began to decrease at 14 days after tumor inoculation. This indicates that after inoculation with Walker 256/S tumor, the progenitors of osteoblasts and ostroclasts lost their balance in the bone turnover, resulting in bone resorption. On the other hand, Walker 256/S carcinoma expressed luteinizing hormone-releasing hormone (LH-RH) mRNA, and in Walker 256/S-bearing rats, the serum LH-RH level increased significantly from 3 days after tumor inoculation, whereas in the healthy control rats, this level was very low. Consequently, the serum levels of follicle-stimulating hormone, luteinizing hormone, estradiol, and progesterone were significantly lower in the tumor-bearing rats than in the healthy control rats. Because the LH-RH gene is located in the long prolactin release-inhibiting factor (PIF) gene and mRNA amplified by reverse transcription-PCR in this study contained whole LH-RH and a part of PIF, the Walker 256/S tumor is thought to express PIF. Indeed, the serum prolactin level decreased in tumor-bearing rats. The serum level of growth hormone, one of the other pituitary hormones, was not changed. Moreover, the level of an osteolytic cytokine, tumor necrosis factor alpha, increased in the serum of Walker 256/S-bearing rats, although this may be a result of the immune response of the host animal to tumor growth as well as an enlarged spleen. In conclusion, the Walker 256/S tumor lowers estrogen secretion through ectopical oversecretion of LH-RH, and then osteolytic cytokines, such as tumor necrosis factor alpha, increase in tumor-bearing rats, escape the control of estrogen, and activate osteoclasts, resulting in bone loss in a short period. PMID:10096551

Waki, Y; Nomura, M; Kasugai, S; Ohya, K; Miyamoto, K

1999-03-15

447

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

NASA Astrophysics Data System (ADS)

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

Busby, C.

2011-12-01

448

Reunion probabilities of $N$ one-dimensional random walkers with mixed boundary conditions  

E-print Network

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 $c\\to\\infty$ (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 (RMT). 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 $F_N(L)=A_N\\sum_{k\\in\\Omega_{B}}\\int Dz e^{-\\sum_{j=1}^Nk_j^2+G_N(k)-\\sum_{j,\\ell=1}^N z_jV_{j\\ell}(k)\\overline{z}_\\ell}$, where $A_N$ is a normalization constant, $G_N(k)$ and $V_{j\\ell}(k)$ depend on the type of boundary condition, and $\\Omega_{B}$ is the solution set of quasi-momenta $k$ obeying the Bethe equations for that particular boundary condition.

Isaac Prez Castillo; Thomas Dupic

2013-11-04

449

Role of the conserved lysine within the Walker A motif of human DMC1  

PubMed Central

During meiosis, the RAD51 recombinase and its meiosis-specific homolog DMC1 mediate DNA strand exchange between homologous chromosomes. The proteins form a right-handed nucleoprotein complex on ssDNA called the presynaptic filament. In an ATP-dependent manner, the presynaptic filament searches for homology to form a physical connection with the homologous chromosome. We constructed two variants of hDMC1 altering the conserved lysine residue of the Walker A motif to arginine (hDMC1K132R) or alanine (hDMC1K132A). The hDMC1 variants were expressed in Escherichia coli and purified to near homogeneity. Both hDMC1K132R and hDMC1K132A variants were devoid of ATP hydrolysis. The hDMC1K132R variant was attenuated for ATP binding that was partially restored by the addition of either ssDNA or calcium. The hDMC1K132R variant was partially capable of homologous DNA pairing and strand exchange in the presence of calcium and protecting DNA from a nuclease, while the hDMC1K132A variant was inactive. These results suggest that the conserved lysine of the Walker A motif in hDMC1 plays a key role in ATP binding. Furthermore, the binding of calcium and ssDNA promotes a conformational change in the ATP binding pocket of hDMC1 that promotes ATP binding. Our results provide evidence that the conserved lysine in the Walker A motif of hDMC1 is critical for ATP binding which is required for presynaptic filament formation. PMID:23182424

Sharma, Deepti; Say, Amanda F.; Ledford, LeAnna L.; Hughes, Ami J.; Sehorn, Hilarie A.; Dwyer, Donard S.; Sehorn, Michael G.

2012-01-01

450

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

451

Blake's pouch cyst: an entity within the Dandy-Walker continuum.  

PubMed

Abnormal cerebrospinal fluid (CSF) collections within the posterior fossa are defined by the Dandy-Walker complex (DWC) and by arachnoid cysts (AC). The DWC includes the Dandy-Walker malformation (DWM), the Dandy-Walker variant (DWV) and the mega-cisterna magna (MCM). In addition, Tortori-Donati et al. added persistent Blake's pouch cyst (BPC) as an independent entity within the DWC. BPC represents a posterior ballooning of the superior medullary velum into the cisterna magna. All of these malformations are overlapping developmental anomalies characterized by varying degrees of malformation of the medullary vela, the cerebellar vermis and hemispheres, the fourth ventricle choroid plexus, the posterior fossa subarachnoid cisterns and the enveloping meningeal structures. We present two cases of persistent BPC detected in two adult women without history of gestational or subsequent growth problems. They underwent neuroradiological investigation because of headache and because of recurrent episodes of loss of consciousness, respectively. The MRI findings included tetraventricular hydrocephalus, wide communication of the fourth ventricle and the cystic posterior fossa (i.e. BPC), inferior posterior fossa mass effect with or without hypoplasia of both the cerebellar vermis and the medial aspects of the cerebellar hemispheres, and absence of communication between fourth ventricle and the basal subarachnoid space in the midline posteriorly. Persistent BPC is defined by a failure of embryonic assimilation of the area membranacea anterior within the tela choroidea associated with imperforation of the foramen of Magendie. Typically this condition becomes symptomatic early in life. In the current cases the normal function of the laterally positioned foramina of Luschka probably helped to maintain some CSF flow between intraventricular and subarachnoid spaces, with the establishment of a precarious equilibrium characterized by a compensatory enlargement of the cerebral ventricular system (i.e. hydrocephalus). PMID:10872175

Calabr, F; Arcuri, T; Jinkins, J R

2000-04-01

452

Quantum Squeezing and Late Time Classical Behavior of Massive Fields in Expanding Robertson-Walker Universe  

E-print Network

A Schroedinger picture analysis of time dependent quantum oscillators, in a manner of Guth and Pi, clearly identifies two physical mechanisms for possible decoherence of vacuum fluctuations in early universe: turning of quantum oscillators upside-down, and rapid squeezing of upside-right oscillators so that certain squeezing factor diverges. In inflationary cosmology the former mechanism explains the stochastic evolution of light inflatons and the classical nature of density perturbations in most of inflationary models, while the later one is responsible for the classical evolution of relatively heavy fields, with masses in a narrow range above the Hubble parameter: 2 Walker cosmology.

Milan Mijic

1997-06-05

453

First Law of Thermodynamics and Friedmann Equations of Friedmann-Robertson-Walker Universe  

E-print Network

Applying the first law of thermodynamics to the apparent horizon of a Friedmann-Robertson-Walker universe and assuming the geometric entropy given by a quarter of the apparent horizon area, we derive the Friedmann equations describing the dynamics of the universe with any spatial curvature. Using entropy formulae for the static spherically symmetric black hole horizons in Gauss-Bonnet gravity and in more general Lovelock gravity, where the entropy is not proportional to the horizon area, we are also able to obtain the Friedmann equations in each gravity theory. We also discuss some physical implications of our results.

Rong-Gen Cai; Sang Pyo Kim

2005-01-08

454

Newtonian and Post-Newtonian approximations of the k = 0 Friedmann Robertson Walker Cosmology  

E-print Network

In a previous paper we derived a post-Newtonian approximation to cosmology which, in contrast to former Newtonian and post-Newtonian cosmological theories, has a well-posed initial value problem. In this paper, this new post-Newtonian theory is compared with the fully general relativistic theory, in the context of the k = 0 Friedmann Robertson Walker cosmologies. It is found that the post-Newtonian theory reproduces the results of its general relativistic counterpart, whilst the Newtonian theory does not.

Tamath Rainsford

1999-07-28

455

Diffractive photon dissociation in the saturation regime from the Good and Walker picture  

E-print Network

Combining the QCD dipole model with the Good and Walker picture, we formulate diffractive dissociation of a photon of virtuality Q^2 off a hadronic target, in the kinematical regime in which Q is close to the saturation scale and much smaller than the invariant mass of the diffracted system. We show how the obtained formula compares to the HERA data and discuss what can be learnt from such a phenomenology. In particular, we argue that diffractive observables in these kinematics provide useful pieces of information on the saturation regime of QCD.

S. Munier; A. Shoshi

2003-12-01

456

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

E-print Network

We show that the Laplace-Beltrami equation $\\square_6 a =j$ in $(\\setR^6,\\eta)$, $\\eta := \\mathrm{diag}(+----+)$, 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.

E. Huguet; J. Renaud

2013-01-31

457

The Relation between the Good-Walker and Triple-Regge Formalisms for Diffractive Excitation  

E-print Network

In this note we analyse the relation between the triple-pomeron and Good-Walker formalisms for diffractive excitation in DIS and hadronic collisions. In both approaches gap events are interpreted as the shadow of absorption into inelastic channels. We here argue that the two formalisms are just different views of the same phenomenon. We first demonstrate how this relation works in a simple toy model, and then show how the relevant features of the toy model are also realized in real perturbative QCD.

Gsta Gustafson

2012-06-08

458

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

E-print Network

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

Ho Lee

2013-07-22

459

Uniqueness of spacelike hypersurfaces with constant higher order mean curvature in generalized Robertson-Walker spacetimes  

E-print Network

In this paper we study the problem of uniqueness for spacelike hypersurfaces with constant higher order mean curvature in generalized Robertson-Walker (GRW) spacetimes. In particular, we consider the following question: Under what conditions must a compact spacelike hypersurface with constant higher order mean curvature in a spatially closed GRW spacetime be a spacelike slice? We prove that this happens, esentially, under the so called convergence condition. Our approach is based on the use of the Newton transformations (and their associated differential operators) and the Minkowski formulae for spacelike hypersurfaces.

Luis J. Alias; A. Gervasio Colares

2007-09-27

460

Proliferation of Walker 256 carcinosarcoma cells: effect of whole-body hyperthermia and antitumor agents.  

PubMed

We studied the main biological characteristics of spontaneous growth of Walker 256 carcinosarcoma and under conditions of antitumor therapy. A combination of whole-body hyperthermia and cytostatic treatment (cyclophosphamide and melatonin) produced maximum suppression of the tumor growth, inhibition of mitotic activity of tumor cells, and stimulation of their necrotic and apoptotic death. The maximum decrease in mitotic activity of tumor cells was observed after combined exposure to whole-body hyperthermia and both cytostatic preparations; enhancement of apoptotic cell death and the decrease in the tumor node weight were also most pronounced under these conditions and practically no body weight loss was recorded in this case. PMID:22803062

Lushnikova, E L; Ovsyanko, E V; Nepomnyashchikh, L M; Efremov, A V; Morozov, D V

2011-11-01

461

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

462

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

463

Brownian Motion in Robertson-Walker Space-Times from electromagnetic Vacuum Fluctuations  

E-print Network

We consider classical particles coupled to the quantized electromagnetic field in the background of a spatially flat Robertson-Walker universe. We find that these particles typically undergo Brownian motion and acquire a non-zero mean squared velocity which depends upon the scale factor of the universe. This Brownian motion can be interpreted as due to non-cancellation of anti-correlated vacuum fluctuations in the time dependent background space-time. We consider several types of coupling to the electromagnetic field, including particles with net electric charge, a magnetic dipole moment, and electric polarizability. We also investigate several different model scale factors.

Carlos H. G. Bessa; Valdir B. Bezerra; L. H. Ford

2008-04-08

464

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

NASA Astrophysics Data System (ADS)

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

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

1994-03-01

465

140 P. L. WALKER,JR.,J. I?. RAICSZAWSKIAND G. R. IMPERIAL Vol. 63 surface area (0.8 m."g.) as compared to that of the  

E-print Network

140 P. L. WALKER,JR.,J. I?. RAICSZAWSKIAND G. R. IMPERIAL Vol. 63 surface area (0.8 m OF CARBON FORMATION BYP. L. WALKER,JR.,J. F. RAKSZAWSKIAND G. R. IMPERIAL Department of Fuel Technology C-H ratio of the cnrboiis is found to increase monoton- ically with increasing formation

466

Characterization of resistance to the Mexican spittlebug complex Aeneolamia albofasciata (Lallemand) and Prosapia simulans (Walker) in selected buffelgrass genotypes  

E-print Network

- btt P Idf gg fbi ~ I I (Wlk ) f152 d223 days at temperatures of 26 and 24 C respectively. Hernandez and Flores (1953) observed an average incubation period of 13. 5 days for eggs of Aeneolamia poetica (Walker) at a temperature of 26 C. Beck (1963...- btt P Idf gg fbi ~ I I (Wlk ) f152 d223 days at temperatures of 26 and 24 C respectively. Hernandez and Flores (1953) observed an average incubation period of 13. 5 days for eggs of Aeneolamia poetica (Walker) at a temperature of 26 C. Beck (1963...

Head, Henry Wesley

2012-06-07

467

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

SciTech Connect

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

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

1987-12-31

468

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

E-print Network

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

Joachim Rambeau; Gregory Schehr

2011-02-08

469

A Class of Almost Equilibrium States in Robertson-Walker Spacetimes  

E-print Network

In quantum field theory in curved spacetimes the construction of the algebra of observables of linear fields is today well understood. However, it remains a non-trivial task to construct physically meaningful states on the algebra. For instance, we are in the unsatisfactory situation that there exist no examples of states suited to describe local thermal equilibrium in a non-stationary spacetime. In this thesis, we construct a class of states for the Klein-Gordon field in Robertson-Walker spacetimes, which seem to provide the first example of thermal states in a spacetime without time translation symmetry. More precisely, in the setting of real, linear, scalar fields in Robertson-Walker spacetimes we define on the set of homogeneous, isotropic, quasi-free states a free energy functional that is based on the averaged energy density measured by an isotropic observer along his worldline. This functional is well defined and lower bounded by a suitable quantum energy inequality. Subsequently, we minimize this functional and obtain states that we interpret as 'almost equilibrium states'. It turns out that the states of low energy, which were recently introduced by Olbermann, are the ground states of the almost equilibrium states. Finally, we prove that the almost equilibrium states satisfy the Hadamard condition, which qualifies them as physically meaningful states.

Muharrem Ksk

2009-01-11

470

Relative velocities for radial motion in expanding Robertson-Walker spacetimes  

E-print Network

The expansion of space, and other geometric properties of cosmological models, can be studied using geometrically defined notions of relative velocity. In this paper, we consider test particles undergoing radial motion relative to comoving (geodesic) observers in Robertson-Walker cosmologies, whose scale factors are increasing functions of cosmological time. Analytical and numerical comparisons of the Fermi, kinematic, astrometric, and the spectroscopic relative velocities of test particles are given under general circumstances. Examples include recessional comoving test particles in the de Sitter universe, the radiation-dominated universe, and the matter-dominated universe. Three distinct coordinate charts, each with different notions of simultaneity, are employed in the calculations. It is shown that the astrometric relative velocity of a radially receding test particle cannot be superluminal in any expanding Robertson-Walker spacetime. However, necessary and sufficient conditions are given for the existence of superluminal Fermi speeds, and it is shown how the four concepts of relative velocity determine geometric properties of the spacetime.

Vicente J. Bols; David Klein

2011-06-20

471

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

PubMed

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. PMID:23317353

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

2013-02-01

472

Action of celecoxib on hepatic metabolic changes induced by the Walker-256 tumour in rats.  

PubMed

The purpose of the present work was to investigate the influence of celecoxib on some hepatic metabolic parameters affected by the Walker-256 tumour in rats. Celecoxib was administered daily (5-50 mg/kg body weight) beginning at the day in which the tumour cells were inocculated. At day 14, the liver was isolated and perfused in order to measure alanine transformation, glycolysis and arginine transformation. Maximal reduction of tumour growth (75%), accompanied by an almost normal weight gain, was attained with a celecoxib dose of 12.5 mg/kg. Diminution of glucose utilization (glycolysis) and inhibition of gluconeogenesis and ureogenesis from alanine caused by the tumor were totally reversed by celecoxib. Oxygen uptake by the liver was also normalized by the drug. Hepatic arginine transformation, which is normally enhanced in rats bearing the Walker-256 tumour, remained elevated in celecoxib-treated animals. It was concluded that preservation of gluconeogenesis and normalization of hepatic glucose utilization can explain, partly at least, the clinical improvement of cancer patients treated with the drug. The lack of action of celecoxib on arginine hydrolysis might indicate that reduction in polyamine synthesis is not a factor contributing to the diminished tumour growth. PMID:17910611

Acco, Alexandra; Alves da Silva, Mrio Henrique da Rocha; Batista, Mrcia Regina; Yamamoto, Nair Seiko; Bracht, Adelar

2007-11-01

473

Analysis and implementation of in-plane stationkeeping of continuously perturbed Walker constellations  

NASA Astrophysics Data System (ADS)

The stationkeeping of symmetric Walker constellations is analyzed by considering the perturbations arising from a high order and degree Earth gravity field and the solar radiation pressure. These perturbations act differently on each group of spacecraft flying in a given orbital plane, causing a differential drift effect that would disrupt the initial symmetry of the constellation. The analysis is based on the consideration of a fictitious set of rotating reference frames that move with the spacecraft in the mean sense, but drift at a rate equal to the average drift rate experienced by all the vehicles over an extended period. The frames are also allowed to experience the J2-precession such that each vehicle is allowed to drift in 3D relative to its frame. A two-impulse rendezvous maneuver is then constructed to bring each vehicle to the center of its frame as soon as a given tolerance deadband is about to be violated. This paper illustrates the computations associated with the stationkeeping of a generic Walker constellation by maneuvering each leading spacecraft within an orbit plane and calculating the associated velocity changes required for controlling the in-plane motions in an exacting sense, at least for the first series of maneuvers. The analysis can be easily extended to lower flying constellations, which experience additional perturbations due to drag.

Kchichian, Jean A.

2009-12-01

474

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

475

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. PMID:23317353

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

476

Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming  

NASA Astrophysics Data System (ADS)

An unprecedented strengthening of Pacific trade winds since the late 1990s (ref. ) has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific, strengthening of Indo-Pacific ocean currents, and an increased uptake of heat in the equatorial Pacific thermocline. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming. In spite of recent progress in determining the climatic impacts of the Pacific trade wind acceleration, the cause of this pronounced trend in atmospheric circulation remains unknown. Here we analyse a series of climate model experiments along with observational data to show that the recent warming trend in Atlantic sea surface temperature and the corresponding trans-basin displacements of the main atmospheric pressure centres were key drivers of the observed Walker circulation intensification, eastern Pacific cooling, North American rainfall trends and western Pacific sea-level rise. Our study suggests that global surface warming has been partly offset by the Pacific climate response to enhanced Atlantic warming since the early 1990s.

McGregor, Shayne; Timmermann, Axel; Stuecker, Malte F.; England, Matthew H.; Merrifield, Mark; Jin, Fei-Fei; Chikamoto, Yoshimitsu

2014-10-01

477

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. PMID:22732065

2012-01-01

478

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

E-print Network

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

Herbert Schwabl; Johannes Mesa Pascasio; Siegfried Fussy; Gerhard Groessing

2012-05-21

479

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

ERIC Educational Resources Information Center

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

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

2005-01-01

480

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

PubMed

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

Badraoui, Riadh; Ben-Nasr, Hmed; Amamou, Selma; El-May, Michle Vronique; Rebai, Tarek

2014-03-01

481

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

E-print Network

; the typical American teenager spends at least an hour of every day play- ing a computer game [26]. In addition. The Entertainment Software Association estimates that computer and video game software sales in 2006 were $7Database Research Opportunities in Computer Games Walker White, Christoph Koch, Nitin Gupta

Gehrke, Johannes

482

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

E-print Network

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

Walker, Jeff

483

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

E-print Network

A 1200 year record of hydrologic variability in the Sierra Nevada from sediments in Walker Lake@usc.edu) John P. McGeehin U.S. Geological Survey, 12201 Sunrise Valley, Reston, Virginia 20192, USA (mcgeehin to AD 800. The timings of variations in the TIC d18 O record are generally consistent with the tree ring

Linsley, Braddock K.

484

Robot reliability using fuzzy fault trees and Markov Martin L. Leuschen, Ian D. Walker, Joseph R. Cavallaro  

E-print Network

Robot reliability using fuzzy fault trees and Markov models Martin L. Leuschen, Ian D. Walker tolerance. Fuzzy logic lends itself to quantitative reliability calculations in robotics. The crisp failure unwarranted assumptions. Fault trees are a standard reliability tool that can easily assimilate fuzzy logic

Cavallaro, Joseph R.

485

FISCAL FORESIGHT: ANALYTICS AND ECONOMETRICS ERIC M. LEEPER, TODD B. WALKER, AND SHU-CHUN SUSAN YANG  

E-print Network

FISCAL FORESIGHT: ANALYTICS AND ECONOMETRICS ERIC M. LEEPER, TODD B. WALKER, AND SHU-CHUN SUSAN policy process. This paper develops an analytical framework to study the econometric implications from statistical innovations in conventional ways. Econometric analyses that fail to align agents

Hickman, Mark

486

Walker, I., Garrard, I. and Jowitt, F. (2014) The influence of a bicycle commuter's appearance on drivers' overtaking  

E-print Network

Walker, I., Garrard, I. and Jowitt, F. (2014) The influence of a bicycle commuter's appearance policies. Please scroll down to view the document. #12;The influence of a bicycle commuter's appearance-visibility bicycling jacket was also used, as were two commercially available safety vests, one featuring a prominent

Burton, Geoffrey R.

487

A Study of Pressure Losses in Residential Air Distribution Systems Bass Abushakra Iain S. Walker Max H. Sherman  

E-print Network

A Study of Pressure Losses in Residential Air Distribution Systems Bass Abushakra Iain S. Walker/240 requirements for minimum external pressure on indoor air-moving equipment, a proper estimate of pressure drops DOE assumptions. Pressure losses in an air distribution system are balanced by pressure increases

488

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

PubMed Central

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

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

2013-01-01

489

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

490

A Simplified Model of the Walker Circulation with an Interactive Ocean Mixed Layer and Cloud-Radiative Feedbacks  

E-print Network

A Simplified Model of the Walker Circulation with an Interactive Ocean Mixed Layer and Cloud-Radiative Cloud­climate feedbacks between precipitation, radiation, circulation strength, atmospheric temperature surface energy budget. Analytic approximations with a simplified radiation scheme are derived and used

Bretherton, Chris

491

ProstateAnalyzer: GUI in Medical Domain with Management of DICOM Images of Prostate Cancer (PCa) , P.M. Walker  

E-print Network

. Mata 1 , P.M. Walker 2, 3 , A. Lalande 2,3 , F. Brunotte 2,3 , A. Oliver 1 , and J. Martí 1 1 Universitat de Girona, Computer Vision and Robotics Group (VICOROB), Girona, Spain 2 Université de Bourgogne

Paris-Sud XI, Université de

492

SIMULATION OF A RELIABLE PARALLEL ROBOT D.L. Hamilton, J.K. Bennett & I.D. Walker  

E-print Network

SIMULATION OF A RELIABLE PARALLEL ROBOT CONTROLLER D.L. Hamilton, J.K. Bennett & I.D. Walker solutions to the robot control problem are an attractive alternative to single­processor systems as the need for fine motion robot control increases. Since multiple processors provide inherent redundancy, par­ allel

Bennett, John K.

493

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

E-print Network

. Walker, and Keith E. Green Abstract-- In this paper, we consider the modeling of robotic continuousForward Kinematic Model for Continuum Robotic Surfaces Jessica Merino Anthony L. Threatt, Ian D "continuum" two-dimensional surfaces. We discuss the fundamental differences between such robot surfaces

494

Parallel FaultTolerant Robot Control D.L. Hamilton, J.K. Bennett, and I.D. Walker  

E-print Network

Parallel Fault­Tolerant Robot Control D.L. Hamilton, J.K. Bennett, and I.D. Walker Dept. of Electrical and Computer Engineering Rice University, Houston, TX 77251 ABSTRACT Most robot controllers today employ a single processor architecture. As robot control requirements become more complex, these serial

Bennett, John K.

495

Giantism and its role in the harmful algal bloom species Phaeocystis globosa Walker O. Smith, Jr.a,*  

E-print Network

1 Giantism and its role in the harmful algal bloom species Phaeocystis globosa Walker O. Smith, Jr), the species is considered a harmful algal bloom species due to the significant indirect effects it has T _______________________ ________________________________________________________________ Keywords: The cosmopolitan alga Phaeocystis globosa forms large blooms in shallow coastal waters

Latour, Robert J.

496

Giantism and its role in the harmful algal bloom species Phaeocystis globosa Walker O. Smith Jr.a,n  

E-print Network

Giantism and its role in the harmful algal bloom species Phaeocystis globosa Walker O. Smith Jr is considered a harmful algal bloom species due to the significant indirect effects it has on local systems via alga Phaeocystis globosa forms large blooms in shallow coastal waters off the Viet Nam coast, which

Newman, Michael C.

497

Leucine-rich diet supplementation modulates foetal muscle protein metabolism impaired by Walker-256 tumour  

PubMed Central

Background Cancer-cachexia induces a variety of metabolic disorders of protein turnover and is more pronounced when associated with pregnancy. Tumour-bearing pregnant rats have impaired protein balance, which decreases protein synthesis and increases muscle breakdown. Because branched-chain amino acids, especially leucine, stimulate protein synthesis, we investigated the effect of a leucine-rich diet on protein metabolism in the foetal gastrocnemius muscles of tumour-bearing pregnant rats. Methods Foetuses of pregnant rats with or without Walker 256 tumours were divided into six groups. During the 20 days of the experiment, the pregnant groups were fed with either a control diet (C, control rats; W, tumour-bearing rats; Cp, rats pair-fed the same normoprotein-diet as the W group) or with a leucine-rich diet (L, leucine rats; LW, leucine tumour-bearing rats; and Lp, rats pair-fed the same leucine-rich diet as the LW group). After the mothers were sacrificed, the foetal gastrocnemius muscle samples were resected, and the protein synthesis and degradation and tissue chymotrypsin-like, cathepsin and calpain enzyme activities were assayed. The muscle oxidative enzymes (catalase, glutathione-S-transferase and superoxide dismutase), alkaline phosphatase enzyme activities and lipid peroxidation (malondialdehyde) were also measured. Results Tumour growth led to a reduction in foetal weight associated with decreased serum protein, albumin and glucose levels and low haematocrit in the foetuses of the W group, whereas in the LW foetuses, these changes were less pronounced. Muscle protein synthesis (measured by L-[3H]-phenylalanine incorporation) was reduced in the W foetuses but was restored in the LW group. Protein breakdown (as assessed by tyrosine release) was enhanced in the L and W groups, but chymotrypsin-like activity increased only in group W and tended toward an increase in the LW foetuses. The activity of cathepsin H was significantly higher in the W group foetuses, but the proteolytic calcium-dependent pathway showed similar enzyme activity. In parallel, an intense oxidative stress process was observed only in the group W foetuses. Conclusions These data suggested that the proteasomal and lysosomal proteolytic pathways and oxidative stress are likely to participate in the process of foetal muscle catabolism of Walkers tumour-bearing pregnant rats. The present work shows that foetal muscle can be protected by supplementation with a leucine-rich diet. PMID:24383706

2014-01-01

498

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

PubMed Central

Implantation of Walker 256 tumor decreases acute systemic inflammation in rats. Inflammatory hyperalgesia is one of the most important events of acute inflammation. The L-arginine/NO/cGMP/K+ATP pathway has been proposed as the mechanism of peripheral antinociception mediated by several drugs and physical exercise. The objective of this study was to investigate a possible involvement of the NO/cGMP/K+ATP pathway in antinociception induced in Walker 256 tumor-bearing male Wistar rats (180-220?g). The groups consisted of 5-6 animals. Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. Walker tumor (4th and 7th day post-implantation) reduced prostaglandin E2- (PGE2, 400?ng/paw; 50?L; intraplantar injection) and carrageenan-induced hypernociception (500?g/paw; 100?L; intraplantar injection). Walker tumor-induced analgesia was reversed (99.3% for carrageenan and 77.2% for PGE2) by a selective inhibitor of nitric oxide synthase (L-NAME; 90?mg/kg, ip) and L-arginine (200?mg/kg, ip), which prevented (80% for carrageenan and 65% for PGE2) the effect of L-NAME. Treatment with the soluble guanylyl cyclase inhibitor ODQ (100% for carrageenan and 95% for PGE2; 8?g/paw) and the ATP-sensitive K+ channel (KATP) blocker glibenclamide (87.5% for carrageenan and 100% for PGE2; 160?g/paw) reversed the antinociceptive effect of tumor bearing in a statistically significant manner (P < 0.05). The present study confirmed an intrinsic peripheral antinociceptive effect of Walker tumor bearing in rats. This antinociceptive effect seemed to be mediated by activation of the NO/cGMP pathway followed by the opening of KATP channels. PMID:22450376

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

2012-01-01

499

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

E-print Network

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

Joachim Schroeter

2009-06-30

500

Transition to Localization of Biased Walkers in a Randomly Absorbing Enviroment  

E-print Network

We study biased random walkers on lattices with randomly dispersed static traps in one, two and three dimensions. As the external bias is increased from zero the system undergoes a phase transition, most clearly manifested in the asymptotic drift velocity of survivors which is zero below a critical bias. This transition is second-order in one dimension but of first order in higher dimensions. The model can be mapped to a stretched polymer with attractive interaction between monomers, and this phase transition would then describe sudden unfolding of the polymer when the stretching force exceeds a critical value. We also present precise simulations of the zero bias case where we show unambiguously that the transition between the Rosenstock and Donsker-Varadhan regimes is first order in dimension $\\ge 2$.

Vishal Mehra; Peter Grassberger

2001-07-25