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1

Oviposition height increases parasitism success by the robber fly Mallophora ruficauda (Diptera: Asilidae)  

Microsoft Academic Search

For parasitoids, host finding is a central problem that has been solved through a variety of behavioural mechanisms. Among species in which females do not make direct contact with hosts, as is the case for many dipteran parasitoids, eggs must be laid in an appropriate part of the host habitat. The asilid fly Mallophora ruficauda lays eggs in clusters on

Marcela K. Castelo; Muriel Ney-Nifle; Juan C. Corley; Carlos Bernstein

2006-01-01

2

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

3

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

4

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 ...

5

Walker receives the Flinn Award  

NASA Astrophysics Data System (ADS)

Raymond Walker was awarded the Edward A. Flinn III Award at the AGU Fall Meeting Banquet on December 17, 1996, in San Francisco, California. The Flinn Award is awarded to recognize those individuals who personify the Union's motto “unselfish cooperation in research” through their facilitating, coordinating, and implementing activities. This award is given not more often than annually. The award citation and Walker's response are given here.

Kivelson, Margaret; Walker, Raymond J.

6

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

7

Walker-Warburg syndrome  

PubMed Central

Walker-Warburg Syndrome (WWS) is a rare form of autosomal recessive congenital muscular dystrophy associated with brain and eye abnormalities. WWS has a worldwide distribution. The overall incidence is unknown but a survey in North-eastern Italy has reported an incidence rate of 1.2 per 100,000 live births. It is the most severe form of congenital muscular dystrophy with most children dying before the age of three years. WWS presents at birth with generalized hypotonia, muscle weakness, developmental delay with mental retardation and occasional seizures. It is associated with type II cobblestone lissencephaly, hydrocephalus, cerebellar malformations, eye abnormalities and congenital muscular dystrophy characterized by hypoglycosylation of ?-dystroglycan. Several genes have been implicated in the etiology of WWS, and others are as yet unknown. Several mutations were found in the Protein O-Mannosyltransferase 1 and 2 (POMT1 and POMT2) genes, and one mutation was found in each of the fukutin and fukutin-related protein (FKRP) genes. Laboratory investigations usually show elevated creatine kinase, myopathic/dystrophic muscle pathology and altered ?-dystroglycan. Antenatal diagnosis is possible in families with known mutations. Prenatal ultrasound may be helpful for diagnosis in families where the molecular defect is unknown. No specific treatment is available. Management is only supportive and preventive. PMID:16887026

Vajsar, Jiri; Schachter, Harry

2006-01-01

8

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

9

WebWalker: Issue 3  

NSDL National Science Digital Library

WebWalker "is a newsletter about the Walker Art Center Websites and digital culture on the net." The third issue features Airworld, net art by Jennifer and Kevin McCoy, and Mark Amerika's PHON:E:ME. Airworld is designed to make readers question what they expect from a Website. At first, the site looks slick and commercial, but then one starts noticing oddities, such as a repeated slide graphic that will not fill in, linked to text does not quite match, and blurry images, all of which raise questions about what kind of site this actually is. PHON:E:ME was launched in June, 1999, and WebWalker coverage includes links to the work itself, a collection of essays, interviews with the artists, and viewer comments.

1999-01-01

10

Mark Walker Director of Public Affairs  

E-print Network

Mark Walker Director of Public Affairs Northwest Power and Conservation Council Dear Mr. Walker, I assistance from the Bonneville Power Administration, which has not raised its conservation budget. If others

11

Abstract models of molecular walkers  

NASA Astrophysics Data System (ADS)

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

Semenov, Oleg

12

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

13

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

14

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

15

75 FR 38833 - Walker River Basin Acquisition Program  

Federal Register 2010, 2011, 2012, 2013, 2014

...OF THE INTERIOR Bureau of Reclamation Walker River Basin Acquisition Program AGENCY...Environmental Impact Statement (EIS) for the Walker River Basin Acquisition Program (Acquisition...INFORMATION: Since 1882, diversions from the Walker River, primarily for irrigated...

2010-07-06

16

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Establishment of Class E Airspace; Walker, MN AGENCY: Federal Aviation Administration...action establishes Class E airspace at Walker, MN. Controlled airspace is necessary...Standard Instrument Approach Procedures at Walker Municipal Airport. The FAA is...

2013-08-08

17

75 FR 51178 - Safety Standard for Infant Walkers; Correction  

Federal Register 2010, 2011, 2012, 2013, 2014

...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

18

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

19

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2013 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical...mechanical walker is a four-legged device with a metal frame intended for medical purposes to...

2013-04-01

20

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2014 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical...mechanical walker is a four-legged device with a metal frame intended for medical purposes to...

2014-04-01

21

21 CFR 890.3825 - Mechanical walker.  

Code of Federal Regulations, 2012 CFR

...SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical...mechanical walker is a four-legged device with a metal frame intended for medical purposes to...

2012-04-01

22

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

23

The Walker Lane in northeastern California  

SciTech Connect

The Walker Lane (Locke and others, 1940) was defined as a narrow northwest-trending dextral fault zone that separates basin- and range topography on the east from diverse topography on the west that extends discontinuously from Lake Mead to Honey Lake. The term Walker Lane Belt (Steward, 1988) expands the feature to include a wide zone east of the Sierra Nevada. Pease (1969), Hannah (1977), and Grose (1986) suggested that the tectonic characteristics of Walker Lane continue into the Modoc Plateau. The authors believe that it is useful to recognize the Walker Lane or Walker Lane Belt in the Modoc Plateau. Within the Modoc Plateau, a 25-km wide (15-mile wide) zone of northwest-southeast faults herein recognized as the Walker Lane, trends N35{degree}W from Honey Lake Basin to Medicine Lake Highland. Mapping in the Eagle Lake area revealed northwest-southeast, north-south, and northeast-southwest late Quaternary faults and rifts, eruptive fissures, small tectonic depressions, and the large Eagle Lake volcano-tectonic depression. To the east is a remarkably unfaulted Neogene volcanic terrane extending 70 km (42 miles) eastward to the Dry Valley-Smoke Creek Desert fault system in Nevada. To the west in the Cascades complex late Pliocene-Quaternary faulting, linear basaltic cones, and andesite volcanoes are all aligned N15{degree}-30{degree}W. This Modoc part of the Walker Lane Belt displays blocks tilted mostly 3{degree}-10{degree}E bounded by west-dipping normal faults and right diagonal normal faults. Left stepping north-south trending rifts occur within northwest trending, straight right diagonal-slip fault zones.

Saucedo, G.J.; Wagner, D.L.; Grose, T.L.T.

1990-01-01

24

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

25

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

26

A simple characterization of generalized Robertson-Walker spacetimes  

NASA Astrophysics Data System (ADS)

A generalized Robertson-Walker spacetime is the warped product with base an open interval of the real line endowed with the opposite of its metric and base any Riemannian manifold. The family of generalized Robertson-Walker spacetimes widely extends the one of classical Robertson-Walker spacetimes. Further, generalized Robertson-Walker spacetimes appear as a privileged class of inhomogeneous spacetimes admitting an isotropic radiation.

Chen, Bang-Yen

2014-12-01

27

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

28

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

29

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

30

Sara Walker | Physical Sciences in Oncology  

Cancer.gov

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

31

Empirical Studies in Discourse Marilyn A. Walker  

E-print Network

a collection of papers illustrating recent approaches to empirical research in discourse generation under investigation (Cohen, 1995; Sparck-Jones and Galliers, 1996; Walker, 1996).1 The role of empirical readers will recognize as a variation of Cohen's EMPIRICAL GENERALIZATION STRATEGY (Cohen, 1995, p.6): 1

Moore, Johanna D.

32

Holography Without Photography Thad G. Walker  

E-print Network

Holography Without Photography Thad G. Walker Department of Physics, University of Wisconsin be useful for lecture demonstration and holography laboratories. Given an arbitrary holographic phase/amplitude plate, computer-generated holography attempts to find a suitable binary encoding of the (complex

Walker, Thad G.

33

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

34

Declarative Processing for Computer Games Walker White  

E-print Network

Declarative Processing for Computer Games Walker White Cornell University wmwhite@cs.cornell.edu Benjamin Sowell Cornell University sowell@cs.cornell.edu Johannes Gehrke Cornell University johannes@cs.cornell.edu Alan Demers Cornell University ademers@cs.cornell.edu Abstract Most game developers think of databases

Keinan, Alon

35

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.

36

The Kneed Walker for human pose tracking  

Microsoft Academic Search

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

Marcus A. Brubaker; David J. Fleet

2008-01-01

37

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

38

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

39

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

40

Conformally Friedmann-Lemaitre-Robertson-Walker cosmologies  

E-print Network

In a universe where, according to the standard cosmological models, some 97% of the total mass-energy is still "missing in action" it behooves us to spend at least a little effort critically assessing and exploring radical alternatives. Among possible, (dare we say plausible), nonstandard but superficially viable models, those spacetimes conformal to the standard Friedmann-Lemaitre-Robertson-Walker class of cosmological models play a very special role --- these models have the unique and important property of permitting large non-perturbative geometric deviations from Friedmann-Lemaitre-Robertson-Walker cosmology without unacceptably distorting the cosmic microwave background. Performing a "cosmographic" analysis, (that is, temporarily setting aside the Einstein equations, since the question of whether or not the Einstein equations are valid on galactic and cosmological scales is essentially the same question as whether or not dark matter/dark energy actually exist), and using both supernova data and informat...

Visser, Matt

2015-01-01

41

Modeling a self-propelled autochemotactic walker  

NASA Astrophysics Data System (ADS)

We develop a minimal model for the stochastic dynamics of microorganisms where individuals communicate via autochemotaxis. This means that microorganisms, such as bacteria, amoebae, or cells, follow the gradient of a chemical that they produce themselves to attract or repel each other. A microorganism is represented as a self-propelled particle or walker with constant speed while its velocity direction diffuses on the unit circle. We study the autochemotactic response of a single self-propelled walker whose dynamics is non-Markovian. We show that its long-time dynamics is always diffusive by deriving analytic expressions for its diffusion coefficient in the weak- and strong-coupling case. We confirm our findings by numerical simulations.

Taktikos, Johannes; Zaburdaev, Vasily; Stark, Holger

2011-10-01

42

Dandy–Walker malformation: An incidental finding  

PubMed Central

Dandy–Walker 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

43

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

44

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

45

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

NASA Astrophysics Data System (ADS)

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

46

Passive random walkers and riverlike networks on growing surfaces  

NASA Astrophysics Data System (ADS)

Passive random walker dynamics is introduced on a growing surface. The walker is designed to drift upward or downward and then follow specific topological features, such as hill tops or valley bottoms, of the fluctuating surface. The passive random walker can thus be used to directly explore scaling properties of otherwise somewhat hidden topological features. For example, the walker allows us to directly measure the dynamical exponent of the underlying growth dynamics. We use the Kardar-Parisi-Zhang (KPZ) -type surface growth as an example. The world lines of a set of merging passive walkers show nontrivial coalescence behaviors and display the riverlike network structures of surface ridges in space-time. In other dynamics, such as Edwards-Wilkinson growth, this does not happen.The passive random walkers in KPZ-type surface growth are closely related to the shock waves in the noiseless Burgers equation. We also briefly discuss their relations to the passive scalar dynamics in turbulence.

Chin, Chen-Shan

2002-08-01

47

Passive random walkers and riverlike networks on growing surfaces.  

PubMed

Passive random walker dynamics is introduced on a growing surface. The walker is designed to drift upward or downward and then follow specific topological features, such as hill tops or valley bottoms, of the fluctuating surface. The passive random walker can thus be used to directly explore scaling properties of otherwise somewhat hidden topological features. For example, the walker allows us to directly measure the dynamical exponent of the underlying growth dynamics. We use the Kardar-Parisi-Zhang (KPZ) -type surface growth as an example. The world lines of a set of merging passive walkers show nontrivial coalescence behaviors and display the riverlike network structures of surface ridges in space-time. In other dynamics, such as Edwards-Wilkinson growth, this does not happen. The passive random walkers in KPZ-type surface growth are closely related to the shock waves in the noiseless Burgers equation. We also briefly discuss their relations to the passive scalar dynamics in turbulence. PMID:12241147

Chin, Chen-Shan

2002-08-01

48

Prevention strategies for infant walker-related injuries.  

PubMed Central

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

Trinkoff, A; Parks, P L

1993-01-01

49

Bidecadal Oscillation in Hadley and Walker Circulations  

NASA Astrophysics Data System (ADS)

Relation between the Bi-Decadal Oscillation and the Hadley and Walker circulations are investigated using NCEP/NCAR reanalysis data. It is known that the BDO has a global distribution but one action center of the atmospheric circulation anomaly associated with the BDO is Aleutian lows. As a representative time series of the BDO, wintertime (DJF) Aleutian low strength known as NPI, which is SLP averaged over 30-65N, 160E-140W, is used. In order to know the relation between the BDO and zonally averaged Hadley circulation, correlation and regression are calculated between the zonally-averaged vertical-meridional mass stream function in four seasons and the wintertime NPI after a 10-30-year band-pass filter was applied to both data. The most well organized structure in the correlations is observed in winter season, with two positive maxima of correlations (r >0.8) at 20S and 35N, which sandwich relatively weak negative correlations over the equator. The vertical extent of the southern high-correlations penetrate up to 200 hPa from 900 hPa, but the high-correlations in the northern hemisphere occur in the lower troposphere. The symmetry is less prominent in regressions, which are much intense in the northern hemisphere. Dominant positive correlations and regressions indicate that when Aleutian low is strong accompanied by negative NPIs, northward (southward) winds generally prevail in the lower (upper) troposphere in the off-equatorial tropics. For the Walker circulation, correlation and regression are calculated between the wintertime NPI and zonal wind speeds meridionally-averaged between 10S and 10N. High correlations and regressions are located in the middle of the troposphere over the western equatorial Pacific. The present results indicate that the BDO influences the Hadley and Walker circulations substantially. The correlations of stream functions prevailing over both the northern and southern hemispheres have significant implications on the inter-hemispheric distribution of the BDO.

Minobe, S.

2002-12-01

50

Intelligent walkers for the elderly: Performance and safety testing of VA-PAMAID robotic walker  

Microsoft Academic Search

A walker that could help navigate and avoid colli- sions with obstacles could help reduce health costs and increase the quality of care and independence of thousands of people. This study evaluated the safety and performance of the Veter- ans Affairs Personal Adaptive Mobility Aid (VA-PAMAID). We performed engineering tests on the VA-PAMAID to deter- mine safety factors, including stability,

Andrew J. Rentschler; Rory A. Cooper; Bruce Blasch; Michael L. Boninger

2003-01-01

51

Walker-Wang models and axion electrodynamics  

NASA Astrophysics Data System (ADS)

We connect a family of gauge theories (Maxwell theories with a magnetoelectric coupling ? =2 ? k ,k ?Z ) to the family of 3D topological lattice models introduced by Walker and Wang. In particular, we show that the lattice Hamiltonians capture a certain strong-coupling limit of these gauge theories, in which the system enters a gapped (confined) phase. We discuss the relationship between the topological order exhibited by certain of these lattice Hamiltonians and the characteristic electromagnetic response of the symmetry-protected bosonic topological insulator.

von Keyserlingk, C. W.; Burnell, F. J.

2015-01-01

52

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

53

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

54

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Proposed Establishment of Class E Airspace; Walker, MN AGENCY: Federal Aviation Administration...proposes to establish Class E airspace at Walker, MN. Controlled airspace is necessary...Instrument Approach Procedures (SIAP) at Walker Municipal Airport. The FAA is...

2013-04-30

55

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

Code of Federal Regulations, 2012 CFR

... Cane, crutch, and walker tips and pads. 890.3790 Section...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are...

2012-04-01

56

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

Code of Federal Regulations, 2013 CFR

... Cane, crutch, and walker tips and pads. 890.3790 Section...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are...

2013-04-01

57

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

Code of Federal Regulations, 2014 CFR

... Cane, crutch, and walker tips and pads. 890.3790 Section...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Cane, crutch, and walker tips and pads. (a) Identification. Cane, crutch, and walker tips and pads are...

2014-04-01

58

Quantum Cohomology via Vicious and Osculating Walkers  

NASA Astrophysics Data System (ADS)

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

Korff, Christian

2014-07-01

59

Department of Mechanical Engineering Spring 2013 Intelligent Walker for Retirees  

E-print Network

a walker with "intelligent" features such as a moving arm, auto- braking wheels, and a control system if supporting the user's weight. Geared Arm Control Caliper Wheel Brakes Distance Sensor and Control ButtonPENNSTATE Department of Mechanical Engineering Spring 2013 Intelligent Walker for Retirees Overview

Demirel, Melik C.

60

Iain S. Walker1 and Max H. Sherman1  

E-print Network

and Construction Sealants and Adhesives, ASTM STP 1453, A. Wolf Ed., American Society for Testing and MaterialsLBNL 50189 1 Iain S. Walker1 and Max H. Sherman1 Sealant Longevity for Residential Ducts Reference: Walker, I.S. and Sherman, M.H., "Sealant Longevity for Residential Ducts," Durability of Building

61

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

62

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

63

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

64

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

65

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

66

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

67

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

68

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

69

Experimental detection of domain wall propagation above the Walker field.  

PubMed

The domain wall (DW) velocity above the Walker field drops abruptly with increasing magnetic field, because of the so-called Walker breakdown, where the DW moves with a precessional mode. On applying the higher field, the DW velocity again starts to increase gradually. We report the DW propagation around this local minimum regime in detail, investigated through the time-resolved electrical detection technique, with a magnetic tunnel junction. Just above the Walker field, we succeeded in detecting the precessional motion of the DW in a real-time regime, while a different mode appeared around the local minimum of the DW velocity. PMID:22173581

Kondou, Kouta; Ohshima, Norikazu; Chiba, Daichi; Kasai, Shinya; Kobayashi, Kensuke; Ono, Teruo

2012-01-18

70

Walker-assisted gait in rehabilitation: a study of biomechanics and instrumentation  

Microsoft Academic Search

While walkers are commonly prescribed to improve patient stability and ambulatory ability, quantitative study of the biomechanical and functional requirements for effective walker use is limited. To date no one has addressed the changes in upper extremity kinetics that occur with the use of a standard walker, which was the objective of this study. A strain gauge-based walker instrumentation system

Rebecca A. Bachschmidt; Gerald F. Harris; Guy G. Simoneau

2001-01-01

71

Interaction of two walkers: Wave-mediated energy and force  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

72

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

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

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

73

Codimension two marginally trapped submanifolds in Robertson-Walker spacetimes  

NASA Astrophysics Data System (ADS)

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 lightlike acceleration in three-dimensional spaces Robertson-Walker spaces, and in the case of codimension two submanifolds whose second fundamental form is lightlike.

Anciaux, Henri; Cipriani, Nastassja

2015-02-01

74

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

75

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

76

Initial conditions of a simple passive-dynamic walker  

NASA Astrophysics Data System (ADS)

Walking robots hold great potential for the future of military robotics. Their natural agility in rough, unstructured terrain make them ideal for military applications but their power requirements do not. Passive dynamic walkers offer a potentially low-power solution. This class of legged robots utilize the natural inverted pendular dynamics that humans rely on to locomote. The most basic of these systems uses gravity as its power source and has no control system therefore its stability is heavily reliant on its initial conditions. The VICON Motion Capture System was used to record the motions of Coleman and Ruina's1 TinkertoyWalker. The initial angles and angular velocities of the various trials were extracted from the motion capture data and used as inputs to a multi-body dynamics model of the walker. The model was created to provide insight into passive-dynamic walkers and the interactions between the walker and the ground surface. Several trials were performed to quantify the stability space of the experimental walker and improve the correlation of the dynamics model to the physical robot.

Haueisen, Brooke; Hudas, Greg; Hulbert, Greg; Nebel, Kyle

2006-05-01

77

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

78

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

79

Intelligent walkers for the elderly: performance and safety testing of VA-PAMAID robotic walker.  

PubMed

A walker that could help navigate and avoid collisions with obstacles could help reduce health costs and increase the quality of care and independence of thousands of people. This study evaluated the safety and performance of the Veterans Affairs Personal Adaptive Mobility Aid (VA-PAMAID). We performed engineering tests on the VA-PAMAID to determine safety factors, including stability, energy consumption, fatigue life, and sensor and control malfunctions. The VA-PAMAID traveled 10.9 km on a full charge and avoided obstacles while traveling at a speed of up to 1.2 m/s. No failures occurred during static stability, climatic, or fatigue testing. Some problems were encountered during obstacle climbing and sensor and control testing. The VA-PAMAID has good range, has adequate reaction time, and is structurally sound. Clinical trials are planned to compare the device to other low-technical adaptive mobility devices. PMID:15080227

Rentschler, Andrew J; Cooper, Rory A; Blasch, Bruce; Boninger, Michael L

2003-01-01

80

Dandy walker variant and bipolar I disorder with graphomania.  

PubMed

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

Can, Serdar Suleyman; Karaka? U?urlu, Görkem; Cakmak, Selcen

2014-07-01

81

[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 Inés; Fernández Cordero, Marisa; Escruela, Romina; Sierra, Valeria; Córdoba, Antonela; Goñi, Ignacio María; Berridi, Ricardo

2014-10-01

82

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

Karaka? U?urlu, Görkem; Çakmak, Selcen

2014-01-01

83

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

84

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

85

Exploring complex networks by means of adaptive walkers.  

PubMed

Finding efficient algorithms to explore large networks with the aim of recovering information about their structure is an open problem. Here, we investigate this challenge by proposing a model in which random walkers with previously assigned home nodes navigate through the network during a fixed amount of time. We consider that the exploration is successful if the walker gets the information gathered back home, otherwise no data are retrieved. Consequently, at each time step, the walkers, with some probability, have the choice to either go backward approaching their home or go farther away. We show that there is an optimal solution to this problem in terms of the average information retrieved and the degree of the home nodes and design an adaptive strategy based on the behavior of the random walker. Finally, we compare different strategies that emerge from the model in the context of network reconstruction. Our results could be useful for the discovery of unknown connections in large-scale networks. PMID:23368013

Prignano, Luce; Moreno, Yamir; Díaz-Guilera, Albert

2012-12-01

86

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 should review an area of research in which John Maynard Smith is very much involved, namely recombination been largely ignored by evolutionary biology; John Maynard Smith is one of those who have brought

Eyre-Walker, Adam

87

A chimeric point-light walker 1 Introduction  

E-print Network

anything odd about the walker, reporting instead that they are watching an unambiguous figure moving either from 11 o'clock to 5 o'clock, can also be seen as a figure moving away from the observer at 458, from 7 o'clock to 1 o'clock (Vanrie et al 2003). In other areas of vision research, relatively simple

Jegelka, Stefanie

88

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

89

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

90

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

91

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

92

DIGITAL SIGNAL PROCESSING--FALL 2012 JAMES S. WALKER  

E-print Network

DIGITAL SIGNAL PROCESSING--FALL 2012 JAMES S. WALKER This course provides a comprehensive introduction to the use of Fourier methods in digital signal processing. Digital signal processing is a vast in sound signals. There is a follow-up course, Digital Image Processing (Math/Phys 440), which treats

Walker, James S.

93

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

94

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

95

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

96

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

97

Efficient multigrid solver for the 3D random walker algorithm  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

98

Network formation determined by the diffusion process of random walkers  

NASA Astrophysics Data System (ADS)

We studied the diffusion process of random walkers in networks formed by their traces. This model considers the rise and fall of links determined by the frequency of transports of random walkers. In order to examine the relation between the formed network and the diffusion process, a situation in which multiple random walkers start from the same vertex is investigated. The difference in diffusion rate of random walkers according to the difference in dimension of the initial lattice is very important for determining the time evolution of the networks. For example, complete subgraphs can be formed on a one-dimensional lattice while a graph with a power-law vertex degree distribution is formed on a two-dimensional lattice. We derived some formulae for predicting network changes for the 1D case, such as the time evolution of the size of nearly complete subgraphs and conditions for their collapse. The networks formed on the 2D lattice are characterized by the existence of clusters of highly connected vertices and their life time. As the life time of such clusters tends to be small, the exponent of the power-law distribution changes from ? sime 1-2 to ? sime 3.

Ikeda, Nobutoshi

2008-06-01

99

A Smart Walker for the Frail Visually Impaired  

Microsoft Academic Search

This paper describes the design of a smart mobility aid for frail, visually impaired people. The device is based on the concept of a walker or rollator-a walking frame with wheels. This work is motivated by the fact the frail visually impaired have extreme difficulty using conventional mobility aids such as guide dogs or long canes. The device, which is

Shane Macnamara; Gerard Lacey

2000-01-01

100

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

101

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 (Sélys) 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

102

Neutrino wave equation in the Robertson-Walker geometry  

NASA Astrophysics Data System (ADS)

The massless Dirac equation is separated in the Robertson-Walker geometry. The Schrödinger-like one-dimensional equation to which the problem is reduced is shown to admit a discrete positive spectrum. The existence or nonexistence of the discrete neutrino energy spectrum is connected, in the case of the standard cosmology, with the assumption that the universe is closed or not.

Montaldi, Emilio; Zecca, Antonio

1994-05-01

103

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

E-print Network

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

104

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

ERIC Educational Resources Information Center

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

SHW Group, Inc., Dallas, TX.

105

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

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

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

106

Department of Mechanical Engineering Spring 2012 Motorized Rolling Walker  

E-print Network

.16 ft.-lb. of torque Added a light-weight Li-Ion battery and a pulse-width-modulator controller battery capacity Tested the combined braking system to ensure they would stop the walker from moving with and without power Battery performed as desired, providing approximately 4 hours of use No yielding

Demirel, Melik C.

107

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

108

Obituary: Alastair Graham Walker Cameron, 1925-2005  

Microsoft Academic Search

Alastair Graham Walker Cameron, one of the most creative and influential astrophysicists of his generation, passed away on 3 October 2005, at the age of 80, at his home in Tucson. Subsequent to his retirement from Harvard University, where he had been a member of the faculty from 1973 through 1999, Cameron remained active as a Senior Research Scientist at

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

2005-01-01

109

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

Federal Register 2010, 2011, 2012, 2013, 2014

...feature is added on some models for convenience to the...Arguably, the force of gravity is more consistent than...only for infant walker models equipped with parking...popular larger, heavier models (greater than 8 pounds...so that the center of gravity will be...

2010-06-21

110

Coarctation of the aorta associated with Dandy–Walker variant  

PubMed Central

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.

2013-01-01

111

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

Microsoft Academic Search

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

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

2006-01-01

112

IRRADIATION DES MTAUX Par R. M. WALKER 1  

E-print Network

474. IRRADIATION DES M�TAUX Par R. M. WALKER 1 Laboratoire de Chimie Physique de la Faculté des Sciences de Paris. Résumé. 2014 On montre que la théorie simple du seuil pour les défauts par irradiation donne une description excellente des principales caractéristiques des modifications induites par l'irradiation

Boyer, Edmond

113

Terrain interaction with the quarter scale beam walker  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

114

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

115

Anisotropic evolution of 5D Friedmann-Robertson-Walker spacetime  

NASA Astrophysics Data System (ADS)

We examine the time evolution of the five-dimensional Einstein field equations subjected to a flat, anisotropic Robertson-Walker metric, where the 3D and higher-dimensional scale factors are allowed to dynamically evolve at different rates. By adopting equations of state relating the 3D and higher-dimensional pressures to the density, we obtain an exact expression relating the higher-dimensional scale factor to a function of the 3D scale factor. This relation allows us to write the Friedmann-Robertson-Walker field equations exclusively in terms of the 3D scale factor, thus yielding a set of 4D effective Friedmann-Robertson-Walker field equations. We examine the effective field equations in the general case and obtain an exact expression relating a function of the 3D scale factor to the time. This expression involves a hypergeometric function and cannot, in general, be inverted to yield an analytical expression for the 3D scale factor as a function of time. When the hypergeometric function is expanded for small and large arguments, we obtain a generalized treatment of the dynamical compactification scenario of Mohammedi [Phys. Rev. DPRVDAQ0556-2821 65, 104018 (2002)10.1103/PhysRevD.65.104018] and the 5D vacuum solution of Chodos and Detweiler [Phys. Rev. DPRVDAQ0556-2821 21, 2167 (1980)10.1103/PhysRevD.21.2167], respectively. By expanding the hypergeometric function near a branch point, we obtain the perturbative solution for the 3D scale factor in the small time regime. This solution exhibits accelerated expansion, which, remarkably, is independent of the value of the 4D equation of state parameter w. This early-time epoch of accelerated expansion arises naturally out of the anisotropic evolution of 5D spacetime when the pressure in the extra dimension is negative and offers a possible alternative to scalar field inflationary theory.

Middleton, Chad A.; Stanley, Ethan

2011-10-01

116

A 'water walkers' exercise program for the elderly.  

PubMed Central

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

Heyneman, C A; Premo, D E

1992-01-01

117

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, Lázaro Faria; Vedolin, Leonardo Modesti

2011-12-01

118

Ground reaction forces of Olympic and World Championship race walkers.  

PubMed

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

Hanley, Brian; Bissas, Athanassios

2014-11-27

119

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

120

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

121

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.

122

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

123

Speech-Plans: Generating Evaluative Responses in Spoken Dialogue M.A. Walker S. Whittaker A. Stent  

E-print Network

Speech-Plans: Generating Evaluative Responses in Spoken Dialogue M.A. Walker S. Whittaker A. Stent¢ walker,stevew,pmaloor,johnston£ @research.att.com SUNY at Stony Brook Stony Brook, NY, USA, 11794 stent

Fisher, Kathleen

124

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

125

The Walker circulation, diabatic heating, and outgoing longwave radiation  

NASA Astrophysics Data System (ADS)

For the tropical atmosphere on planetary scales, it is common to model the circulation using strong damping. Here with new data analysis techniques, evidence suggests that damping can actually be neglected. Specifically, near the equator, the east-west overturning circulation is in agreement with the undamped wave response to atmospheric heating. To estimate the heating, satellite observations of outgoing longwave radiation (OLR) are used. Frequently, OLR is used as a heuristic indicator of cloudiness. Here the results further suggest that OLR variations are actually proportional to diabatic heating variations, with a proportionality constant of 18 W m-2 (K d-1)-1. While the agreement holds best over long time averages of years or decades, it also holds over shorter periods of one season or 1 month. Consequently, it is suggested that the strength of the Walker circulation—and its evolution in time—could be estimated using satellite data.

Stechmann, Samuel N.; Ogrosky, H. Reed

2014-12-01

126

Higgs effective potential in a perturbed Robertson-Walker background  

NASA Astrophysics Data System (ADS)

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 field and evaluate the effects of metric perturbations on the Higgs mass and on its vacuum expectation value. Space-time variations are found, which are proportional to the gravitational slip parameter, with a typical amplitude of the order of ? ? /? ?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.; Prada, Francisco

2014-12-01

127

Maximal distance travelled by N vicious walkers till their survival  

E-print Network

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 $0stopped at time $t_s$ when either two of them collide or when the particle closest to the origin hits the origin for the first time. For $N=2$, we study the probability distribution function $p_1(m|{\\bf{u}})$ and $p_2(m|{\\bf{u}})$ of the maximal distance travelled by the $1^{\\text{st}}$ and $2^{\\text{nd}}$ walker 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^{\

Anupam Kundu; Satya N. Majumdar; Gregory Schehr

2014-02-17

128

Improved solubility of replication factor C (RFC) Walker A mutants  

PubMed Central

Protein insolubility often poses a significant problem during purification protocols and in enzyme assays, especially for eukaryotic proteins expressed in a recombinant bacterial system. The limited solubility of replication factor C (RFC), the clamp loader complex from Saccharomyces cerevisiae, has been previously documented. We found that mutant forms of RFC harboring a single point mutation in the Walker A motif were even less soluble than the wild-type complex. The addition of maltose at 0.75 M to the storage and assay buffers greatly increases protein solubility and prevents the complex from falling apart. Our analysis of the clamp loading reaction is dependent on fluorescence-based assays, which are environmentally sensitive. Using wt RFC as a control, we show that the addition of maltose to the reaction buffers does not affect fluorophore responses in the assays or the enzyme activity, indicating that maltose can be used as a buffer additive for further downstream analysis of these mutants. PMID:22469630

Marzahn, Melissa R.; Bloom, Linda B.

2013-01-01

129

Generalized holographic equipartition for Friedmann-Robertson-Walker universes  

NASA Astrophysics Data System (ADS)

The novel idea that spatial expansion of our universe can be regarded as the consequence of the emergence of space was proposed by Padmanabhan. By using of the basic law governing the emergence, which Padmanabhan called holographic equipartition, he also arrives at the Friedmann equation in a flat universe. When generalized to other gravity theories, the holographic equipartition need to be generalized with an expression of . In this paper, we give general expressions of for generalized holographic equipartition which can be used to derive the Friedmann equations of the Friedmann-Robertson-Walker universe with any spatial curvature in higher ()-dimensional Einstein gravity, Gauss-Bonnet gravity and more general Lovelock gravity. The results support the viability of the perspective of holographic equipartition.

Ai, Wen-Yuan; Chen, Hua; Hu, Xian-Ru; Deng, Jian-Bo

2014-04-01

130

The Enigmatic Young Object: Walker 90/V590 Mon  

NASA Astrophysics Data System (ADS)

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

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

2002-12-01

131

Active Faulting in the Central Walker Lane and Excelsior Trend, Nevada and California  

NASA Astrophysics Data System (ADS)

The San Andreas fault system and strike-slip faults of the Walker Lane accommodate most Pacific-North American plate motion. The style of faulting differs in the two regions. Whereas the San Andreas system is characterized by a relatively continuous and anastomosing set of faults, northwest trending zones of strike-slip faults within the Walker Lane are discontinuous and truncated by northeast trending cross-faults. The differences in style may be coupled to the observations that strike-slip faulting in the Walker Lane is transtensional, and that the cumulative amount of strike-slip in the Walker Lane (<60-80km) is less than that accumulated by the San Andreas. The Excelsior Trend includes a set of east to northeast-striking faults and is immediately between faults of the Central and Southern Walker lane, which are defined by zones of northwest-striking right-lateral and normal faults. Mapping within the Excelsior Trend shows that transfer of slip between the Central and Southern Walker Lane is shared between northeast to east-striking normal and left-lateral faults. Hence, the partitioning of motion between subparallel normal and strike-slip faulting is common to both the Excelsior Trend and the Central and Southern portions of the Walker Lane. Radiocarbon, tephra correlation, and soils lend some initial insights to establishing the recency and rates of motion of faults in the region.

Wesnousky, S. G.

2002-12-01

132

Modelling the Bid and Ask Prices of Illiquid CDSs Michael B. Walker1,2  

E-print Network

Modelling the Bid and Ask Prices of Illiquid CDSs Michael B. Walker1,2 Working Paper First version Program on Quantitative Finance, Toronto, January-June, 2010, as well as John Chinneck, Ken Jackson, Roy

Walker, Michael B.

133

ISS Update: Orion Recovery and Rescue Lead Tom Walker - Duration: 5:03.  

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...

134

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

SciTech Connect

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.

Erdmenger, Johanna; Meyer, Rene [Max-Planck-Institut fuer Physik, 80805 Munich (Germany); Park, Jeong-Hyuck [Max-Planck-Institut fuer Physik, 80805 Munich (Germany); Dept. of Physics, Sogang University, Seoul 121-742 (Korea, Republic of)

2007-06-29

135

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

PubMed

Using a novel, string theory-inspired formalism based on a Hamiltonian constraint, we obtain a conformal mechanical system for the spatially flat four-dimensional Robertson-Walker Universe. Depending on parameter choices, this system describes either a relativistic particle in the Robertson-Walker background or metric fluctuations of the Robertson-Walker geometry. Moreover, we derive a tree-level M theory matrix model in this time-dependent background. Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy near the big bang, while the classical Robertson-Walker geometry emerges as the Universe expands. From our approach, we also derive the temperature of the Universe interpolating between the radiation and matter dominated eras. PMID:17678078

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

2007-06-29

136

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

Code of Federal Regulations, 2011 CFR

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

2011-04-01

137

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

Code of Federal Regulations, 2010 CFR

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

2010-04-01

138

Electrostatic Control of Spontaneous Vesicle Aggregation Scott A. Walker and Joseph A. Zasadzinski*  

E-print Network

Electrostatic Control of Spontaneous Vesicle Aggregation Scott A. Walker and Joseph A. Zasadzinski of the specific recognition interaction makes controlling aggregation via electrostatics possible. These results also suggest that electrostatic interactions are at least somewhat responsible for the stability

Zasadzinski, Joseph A.

139

Politics, aesthetics and diverse sexualities in the work of James Baldwin, Alice Walker and Toni Morrison   

E-print Network

The thesis investigates the ways in which James Baldwin, Alice Walker and Toni Morrison’s fictional portrayals of forms of love, eroticism and sexuality that are excluded or prohibited by social norms, destabilise ...

Sussman, Kathryn Judith

2011-07-01

140

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

E-print Network

Rules in High Pressure Optical Pumping Experiments", B. Lancor, E. Babcock, R. Wyllie, and T. G. Walker-7 DAMOP Nomination Committee, Chair. 2007 Organizer, Midwest Cold Atoms Workshop Chosen as "Outstanding

Walker, Thad G.

141

Linearization stability of the Einstein equation for Robertson-Walker models. II  

NASA Astrophysics Data System (ADS)

In a previous paper (referred to here as paper I) we showed that the Einstein equation is linearization stable when a Robertson-Walker model of curvature K=0 is considered. For that purpose, a slightly different definition of linearization stability was introduced. In this paper we show that in case the curvature K is equal to 1 the Einstein equation G(g)=?T is not linearization stable at the Robertson-Walker metric.

Bruna, Lluís; Girbau, Joan

1999-10-01

142

[Apropos of a case of Dandy-Walker syndrome associated with chromosome abnormalities].  

PubMed

A case of Dandy-Walker syndrome associated with chromosome abnormalities (46,XX,-21, +der(13)t(13;21)(q22;q11), diagnosed during pregnancy is reported. This is a pathology characterized by malformations of the central nervous system, mainly of the cerebellum. Due to several aspects and different prognosis between classic Dandy-Walker and its variants, many clinical and therapeutic problems may raise. PMID:10352541

Patacchiola, F; Carta, G; Iovenitti, P; Bonitatibus, A; Mascaretti, G; Caserta, D; Moscarini, M

1999-03-01

143

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

PubMed

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

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

2015-01-01

144

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

145

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

146

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

147

A jump persistent turning walker to model zebrafish locomotion.  

PubMed

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

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

2015-01-01

148

Paths of Friedmann-Robertson-Walker brane models  

NASA Astrophysics Data System (ADS)

The dynamics of brane-world models of dark energy is reviewed. We demonstrate that simple dark energy brane models can be represented as two-dimensional dynamical systems of a Newtonian type. Hence a fictitious particle moving in a potential well characterizes the model. We investigate the dynamics of the brane models using methods of dynamical systems. The simple brane-world models can be successfully unified within a single scheme-an ensemble of brane dark energy models. We characterize generic models of this ensemble as well as exceptional ones using the notion of structural stability (instability). Then due to the Peixoto theorem we can characterize the class of generic brane models. We show that the global dynamics of the generic brane models of dark energy is topologically equivalent to the concordance ?CDM model. We also demonstrate that the bouncing models or models in which acceleration of the universe is only transient phenomenon are nongeneric (or exceptional cases) in the ensemble. We argue that the adequate brane model of dark energy should be a generic case in the ensemble of Friedmann-Robertson-Walker dynamical systems on the plane.

Szyd?owski, Marek; Hrycyna, Orest

2008-07-01

149

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

150

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

151

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

152

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

153

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

154

Does the Walker Lane extend through the Nevada test site region  

SciTech Connect

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

Fridrich, C.; O'Leary, D. (Geological Survey, Denver, CO (United States). Denver Federal Center)

1993-04-01

155

Corrections to the Walker-Thompson estimate of the cascade volume  

NASA Astrophysics Data System (ADS)

Sigmund [P. Sigmund, Appl. Phys. Lett. 25 (1974) 169] analytically predicted that the ratio of cascade volume to energy distribution volume should follow a universal curve that is sigmoidal in shape. Subsequent Monte Carlo simulations by Walker and Thompson [R.S. Walker, D.A. Thompson, Radiat. Eff. 37 (1978) 113] showed that although this curve is sigmoidal in shape, the curve is different for different materials with large deviations from Sigmund's prediction at high M2/ M1. Our analysis of the Walker and Thompson approach has revealed an error in the analytical equations used. A correct analysis of volume ratios using a different set of equations is presented. Analysis of data produced by SRIM [J.F. Ziegler, J.P. Biersack, U. Littmark, in: The Stopping and Range of Ions in solids, Pergamon, New York, 1985] (Monte Carlo) simulations gives results that are in good agreement with Sigmund's predictions.

Swaminarayan, S.; Nastasi, M.

2009-05-01

156

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

PubMed Central

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

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

2011-01-01

157

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

158

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

159

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

NASA Technical Reports Server (NTRS)

The research pilots at what in 1962 was called the Flight Research Center standing in front of the X-1E. They are (left to right) Neil Armstrong, Joe Walker, Bill Dana, Bruce Peterson, Jack McKay, Milt Thompson, and Stan Butchart. of the group, Armstrong, Walker, Dana, McKay and Thompson all flew the X-15. Bruce Peterson flew the M2-F2 and HL-10 lifting bodies, while Stan Butchart was the B-29 drop plane pilot for many of the D-558-II and X-1 series research aircraft.

1962-01-01

160

[Ocular alterations in a pediatric patient with Dandy-Walker malformations: case report].  

PubMed

We describe a rare case of Dandy-Walker syndrome malformation and its ocular alterations. A female child, aged 1 year and 9 month, with central nervous system alterations (Dandy-Walker syndrome), associated with low visual acuity, megalocornea (13 mm diameter in right eye and 13.5 mm in the left), fundoscopy with 0.7 optic papilla excavation in both eyes (BE) and temporal paleness in BE, intraocular pressure of 16 mmHg in the right eye and 14 mmHg in the left and anteroposterior diameter of 20.55 mm in both eyes. PMID:16491242

Ewald, Oscar; Scremin, Fernanda; Busch, Fábio; Von Hertwig, Roberto

2006-01-01

161

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-11-14

162

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

163

Technology Scaling Issues of an IDDQ Built-In Current Sensor Bin Xue, D. M. H. Walker  

E-print Network

Technology Scaling Issues of an IDDQ Built-In Current Sensor Bin Xue, D. M. H. Walker Dept, walker}@cs.tamu.edu Abstract Analysis and comparison of 1.5 µm and 350 nm CMOS test chip results of a built-in current sensor design reveal several critical design issues. This paper includes a discussion

Walker, Duncan M. "Hank"

164

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

165

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

166

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.

167

Greg Walker, PhD Regius Professor of Rhetoric and English Literature  

E-print Network

AND IRISH LITERATURE FROM 1900 TO THE PRESENT WEEK ONE: MODERNISM JULY Monday 7 8.00 pm Welcome Reception: The Prime of Miss Jean Brodie Wednesday 30 10.00 am James Kelman & Liz Lochhead DR SCOTT LYALL ModernLiteratureDEAN Greg Walker, PhD Regius Professor of Rhetoric and English Literature University of Edinburgh

Swain, Peter

168

Spin-rotation interaction of alkali-metalHe-atom pairs Thad G. Walker  

E-print Network

. Helium, how- ever, has such small spin-orbit interactions that the spin- rotation coupling must originateSpin-rotation interaction of alkali-metal­He-atom pairs Thad G. Walker Department of Physics of the spin-rotation coupling between alkali-metal atoms and He atoms is presented. Rotational distortions

Thywissen, Joseph

169

Tunable Networks from Thiolene Chemistry for Lithium Ion Catherine N. Walker,  

E-print Network

-in-salt regimes. Thermal, mechanical, and ion conductivity properties of LiTFSI-loaded PEG and PEG-PDMS networks,6 For a solid material to replace liquid and gel electrolytes, it should have a minimum ion conductivity of 10Tunable Networks from Thiolene Chemistry for Lithium Ion Conduction Catherine N. Walker, Craig

Tew, Gregory N.

170

Sleep and the Time Course of Motor Skill Learning Matthew P. Walker,1  

E-print Network

of sleep, and that selective disruption of rapid eye movement (REM) sleep prevents this overnightResearch Sleep and the Time Course of Motor Skill Learning Matthew P. Walker,1 Tiffany Brakefield 02115, USA Growing evidence suggests that sleep plays an important role in the process of procedural

Walker, Matthew P.

171

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

Microsoft Academic Search

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

Rong-Gen Cai; Sang Pyo Kim

2005-01-01

172

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 for Assistance 2.USDA Assistance Available in Areas Designated as Natural Disaster Areas 3.USDA Assistance in the United States has a USDA agency office that can help citizens find the right place to apply

Watson, Craig A.

173

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

ERIC Educational Resources Information Center

This document describes the sustainable features of the Roy Lee Walker Elementary School (Texas), a prototype "Eco Education" school that blends the physical environment with the student learning process while protecting the site. The document also presents the process of integrating sustainability criteria in all phases of the school's life…

SHW Group, Inc., Dallas, TX.

174

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

E-print Network

by a variety of dementing disorders including Alzheimer's disease (AD) [5], Parkinson's disease, and multiple sclerosis [6]. Among individuals with the most common of these disorders, dementia of the Alzheimer type on walkers are currently in development, including the Personal Aid for Mobility and Monitoring (PAMM) [9

Kulyukin, Vladimir

175

Power watersheds: A new image segmentation framework extending graph cuts, random walker and optimal spanning forest  

Microsoft Academic Search

In this work, we extend a common framework for seeded image segmentation that includes the graph cuts, ran- dom walker, and shortest path optimization algorithms. Viewing an image as a weighted graph, these algorithms can be expressed by means of a common energy func- tion with differing choices of a parameter q acting as an exponent on the differences between

Camille Couprie; Leo J. Grady; Laurent Najman; Hugues Talbot

2009-01-01

176

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

177

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

178

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

179

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

180

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

181

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

182

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

ERIC Educational Resources Information Center

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

Bahr, Kathy

2010-01-01

183

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

184

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

185

Existence of black holes in Friedmann-Robertson-Walker universe dominated by dark energy  

E-print Network

We study the existence of black holes in a homogeneous and isotropic expanding Friedmann-Robertson-Walker (FRW) universe dominated by dark energy. We show that black holes can exist in such a universe by considering some specific McVittie solutions. Although these solutions violate all three energy conditions, the FRW background does satisfy the weak energy condition.

Zhong-Heng Li; Anzhong Wang

2006-11-15

186

Ventilation Requirements in Hot Humid Iain S. Walker and Max H. Sherman  

E-print Network

LBNL-59889 Ventilation Requirements in Hot Humid Climates Iain S. Walker and Max H. Sherman residential ventilation standard, ASHRAE Standard 62.2. Meeting this standard in new construction requires the use of mechanical ventilation, which in turn can often significantly increase the latent load faced

187

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

E-print Network

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

California at Santa Cruz, University of

188

ANDERSON ACCELERATION FOR FIXED-POINT ITERATIONS HOMER F. WALKER AND PENG NI  

E-print Network

ANDERSON ACCELERATION FOR FIXED-POINT ITERATIONS HOMER F. WALKER AND PENG NI Abstract. This paper concerns an acceleration method for fixed-point iterations that originated in work of D. G. Anderson-560], which we accordingly call Anderson acceleration here. This method has enjoyed considerable success

Walker, Homer F.

189

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

E-print Network

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

Eyre-Walker, Adam

190

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

E-print Network

model. This issue brings together a collection of papers illustrating recent approaches to \\Lambda AT under investigation (Cohen, 1995; Sparck­Jones and Galliers, 1996; Walker, 1996). 1 The role will recognize as a variation of Cohen's empirical generalization strategy (Cohen, 1995, p.6): 1. Feature

Moore, Johanna D.

191

Mary Broadfoot Walker (1888–1974): A Historic Discovery in Myasthenia gravis  

Microsoft Academic Search

As a clinical entity, myasthenia gravis was not recognized until Samuel Wilks in 1877 described bulbar and peripheral muscular weakness. In the Lancet of June 2, 1934, the remarkable discovery of physostigmine treatment by Dr. Mary Walker was published, which was to become the mainstay of symptomatic treatment. A quiet and modest physician, she laboured with considerable success under many

J. M. S. Pearce

2005-01-01

192

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

PubMed

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

Keast, David H; Vair, Audra H

2013-12-01

193

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

194

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

E-print Network

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

195

Writing a Rationale for a Controversial Common Reading Book: Alice Walker's "The Color Purple."  

ERIC Educational Resources Information Center

Offers a rationale that can be used to defend the assignment of Alice Walker's controversial novel for class reading. Indicates four issues that might evoke calls for censorship: (1) subject matter, (2) vocabulary, (3) grammar, and (4) the epistolary form of the work. (RBW)

Worthington, Pepper

1985-01-01

196

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.

197

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

E-print Network

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

198

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

199

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

E-print Network

1 The Northern Walker Lane Refraction Experiment: Pn Arrivals and the Northern Sierra Nevada Root a new crustal refraction profile from Battle Mountain, Nevada across western Nevada, the Reno area, Lake. This refraction survey observes an unexpectedly deep crustal root under the northern Sierra Nevada range, over 50

200

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

E-print Network

The northern Walker Lane refraction experiment: Pn arrivals and the northern Sierra Nevada root August 2004 Abstract In May 2002, we collected a new crustal refraction profile from Battle Mountain also appear in the records. This refraction survey observes an unexpectedly deep crustal root under

201

Automatic Generation of Data-Processing Tools Yitzhak Mandelbaum and David Walker  

E-print Network

Automatic Generation of Data-Processing Tools Yitzhak Mandelbaum and David Walker Department loaders. In this talk we will describe PADS, a system for automatic generation of data processing tools. In particular, the PADS compiler generates a parser library capable of detecting and recovering from data errors

Singh, Jaswinder Pal

202

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.

203

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

NASA Astrophysics Data System (ADS)

The northern Walker Lane, in the western Basin and Range Province of the United States, is a complex system of dextral, normal and sinestral faults that work together to accommodate approximately 9 mm/yr of relative motion between the Sierra Nevada/Great Valley block and the more slowly extending Province. GPS measurements made using the BARGEN, EarthScope PBO and MAGNET GPS networks since 2004 are now providing improved resolution of deformation patterns and crustal fault slip rates inside the Walker Lane and western Basin and Range. We have processed all the GPS data as part of a uniform global solution, and filtered the solution on a Great Basin spatial scale to obtain rates of motion of the Walker Lane crust with respect to North America. Using these rates we have constrained slip rates on regional faults using a block model whose boundaries conform to Quaternary surface rupture geometries. These results show a very strong correlation between the geologic domains and style of strain measured with GPS. In particular, east of the Walker Lane, where the topography and crustal faulting are characteristic of classic Basin and Range tectonic extension, the GPS velocities show a highly uniform southeast to northwest uniaxial extension of 2.5 mm/yr distributed over 250 km. This uniform extension implies normal slip rates of approximately 0.1 mm/yr on average for each fault (horizontal extension). The transition between Basin and Range morphology and the Walker Lane is matched in the GPS velocities by a transition from uniaxial extension to transtension that is resolved into dextral slip on northwest trending faults, with minor contributions from left lateral slip on northeast striking faults and normal slip. Right oblique extension is well-distributed across the Walker Lane, with most faults contributing some slip to accommodate the overall slip budget. The greatest slip rates occur on the western and eastern margins, and by far the greatest amount of normal slip occurs in the westernmost fault systems near the Sierra Nevada crest, Lake Tahoe, and Carson Range faults where horizontal extension rates normal to the fault are as high as 1.8 mm/yr. Normal slip rates elsewhere in the Walker Lane are similar in rate to the rest of the Basin and Range. The Mohawk Valley fault slips faster than any fault in the entire system, about 2.8 mm/yr of dextral slip. These results suggest that contemporary extension on normal faults nearest the Sierra Nevada Range Front may drive the seismic hazard for the nearby Reno/Tahoe metropolitan areas.

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

2009-05-01

204

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

205

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, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ?85-100km wide, where the basins are elongated E-W to ENE, small (?15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ?5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

Jayko, Angela S.; Bursik, Marcus

2012-01-01

206

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

207

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

208

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

Cancer.gov

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

209

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

NASA Astrophysics Data System (ADS)

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* ? log2 (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; Paz, Juan Pablo; Saraceno, Marcos

2006-01-01

210

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

211

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

212

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

213

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, Yi?it; ?zci, Filiz; Semiz, Umit Basar

2014-01-01

214

Linearization stability of the Einstein equation for Robertson-Walker models. I  

NASA Astrophysics Data System (ADS)

This is the first part of a series of two papers. In this article we study the linearization stability of the Einstein equation in the presence of matter. We have slightly changed the classic definition of this concept for the vacuum spacetime and a more general one adapted to our case is given. We consider a Robertson-Walker model (V,g,T) where V stands for the spacetime, g for a Robertson-Walker metric, and T for a stress-energy tensor of a perfect fluid. We write V=S×I where S is a spacelike hypersurface of V and I an R-interval. We show that in the case S has a constant curvature K equal to 0, the Einstein equation G(g)=?T is linearization stable at g. In a subsequent paper we shall prove that in the case K=1 the opposite occurs. The case K=-1 remains as an open question.

Bruna, Lluís; Girbau, Joan

1999-10-01

215

Dandy-walker syndrome with severe velopharyngeal dysfunction: a contraindication for le fort I surgery?  

PubMed

Dandy-Walker syndrome is a rare congenital brain deformation. Most symptoms are related with fourth ventricle and skull base malformations. Quite often, symptoms develop from infancy or progress rapidly. Cerebellar dysfunction, lack of muscle coordination, and skull deformities involving eye movement might be present. There are several Dandy-Walker syndrome complex types. We present a 23-year-old patient who had a severe dentofacial deformity with mandibular prognathism and extremely undeveloped maxillary bone resulting in palatopharyngeal and velopharyngeal dysfunction with complete lack of soft palate function resulting in increased speech tone and volume. Performing Le Fort I osteotomy in this case is greatly controversial and might result in even greater loss of function or even its total lack. Velopharyngeal complex is very important, and every surgeon should consider its value while planning Le Fort I osteotomies. PMID:25565232

Nelke, Kamil H; Pawlak, Wojciech; Gerber, Hanna

2015-01-01

216

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

217

Mary B. Walker, M.D. and the pioneering use of prostigmin to treat myasthenia gravis  

Microsoft Academic Search

In an era when women were not admitted to the University of Edinburgh and when England's first female physician (Elizabeth\\u000a Garrett Anderson, 1836–1917) had to venture to Paris, France, to earn her M.D. in 1870, the career of Mary Broadfoot Walker\\u000a (Figure 1) (1888–1974) stands out for truly remarkable achievement. She is credited with making the most significant discovery\\u000a in

ARTHUR H. KEENEYJ; Virginia T. Keeney

1997-01-01

218

Mary B. Walker, M.D. and the pioneering use of prostigmin to treat myasthenia gravis.  

PubMed

In an era when women were not admitted to the University of Edinburgh and when England's first female physician (Elizabeth Garrett Anderson, 1836-1917) had to venture to Paris, France, to earn her M.D. in 1870, the career of Mary Broadfoot Walker (Figure 1) (1988-1974) stands out for truly remarkable achievement. She is credited with making the most significant discovery in medical therapeutic within the British empire. PMID:9476610

Keeney, A H; Keeney, V T

1997-01-01

219

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

220

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

221

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

SciTech Connect

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.

Brisudova, Martina; Kinney, William H.

2000-11-15

222

Visual ratings of point-light-walkers - a new method to detect paedophilic interests?  

Microsoft Academic Search

pHuman gait contains a huge amount of socially relevant information and even highly reduced visual stimuli such as Point-Light-Walkers (PLWs) are sufficient to transmit information about a walking person’s gender and age. The aim of our study is to develop a new perception-based method for the detection of paedophilic interests using PLWs as stimulus material. The advantage of PLWs is

A. König; A. Schölmerich; N. F. Troje

2006-01-01

223

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

NASA Technical Reports Server (NTRS)

A group photo of NASA research pilots at the front door of the Flight Research Center headquarters building. In the front row are (left to right) Milt Thompson, Jack McKay, and Bill Dana. All three flew the X-15, and Thompson and Dana were also involved in the lifting body flights. McKay was injured in a crash landing in X-15 #2. Although he recovered, the injuries eventually forced him to retire from research flying. In the back row (left to right) are Neil Armstrong, Bruce Peterson, Stanley Butchart, and Joe Walker. Armstrong and Walker also both flew the X-15. Soon after this photo was taken, Armstrong was selected as an astronaut, and seven years later became the first man to walk on the Moon. Walker made the highest flight in the X-15, reaching 354,200 feet. He then went on to fly the Lunar Landing Research Vehicle, and was killed on June 8, 1966 when his F-104N collided with the XB-70. Peterson made the first flight in the HL-10 lifting body, and was later badly injured in the crash of the M2-F2 lifting body. Butchart flew a wide range of research missions in the 1950s, and was the B-29 drop plane pilot for a number of rocket flight.

1962-01-01

224

Equatorial Pacific coral geochemical records show recent weakening of the Walker Circulation  

NASA Astrophysics Data System (ADS)

Pacific ocean-atmosphere interactions affect climate globally, and a key component of the coupled system is the Walker Circulation, which is driven by sea surface temperature (SST) gradients across the equatorial Pacific. There is conflicting evidence as to whether the SST gradient and Walker Circulation have strengthened or weakened over the late twentieth century. We present new records of SST and sea surface salinity (SSS) spanning 1959-2010 based on paired measurements of Sr/Ca and ?18O in a massive Porites coral from Butaritari atoll in the Gilbert Islands, Republic of Kiribati, in the central western equatorial Pacific. The records show 2-7 year variability correlated with the El Niño-Southern Oscillation (ENSO) and corresponding shifts in the extent of the Indo-Pacific Warm Pool, and decadal-scale signals related to the Pacific Decadal Oscillation and the Pacific Warm Pool Index. In addition, the Butaritari coral records reveal a small but significant increase in SST (0.39°C) from 1959 to 2010 with no accompanying change in SSS, a trend that persists even when ENSO variability is removed. In contrast, larger increases in SST and SSS are evident in coral records from the equatorial Pacific Line Islands, located east of Butaritari. Taken together, the equatorial Pacific coral records suggest an overall reduction in the east-west SST and SSS gradient over the last several decades, and a recent weakening of the Walker Circulation.

Carilli, Jessica E.; McGregor, Helen V.; Gaudry, Jessica J.; Donner, Simon D.; Gagan, Michael K.; Stevenson, Samantha; Wong, Henri; Fink, David

2014-11-01

225

The influence of ENSO on the equatorial Atlantic precipitation through the Walker circulation in a CGCM  

NASA Astrophysics Data System (ADS)

The link between El Niño/Southern Oscillation (ENSO) and the equatorial Atlantic precipitation during boreal spring (March-April-May) is explored using a coupled general circulation model (CGCM). Interannual variability of the equatorial Atlantic sea surface temperature (SST) in the CGCM is excluded by nudging the modeled SST toward the climatological monthly mean of observed SST in the equatorial Atlantic, but full air-sea coupling is allowed elsewhere. It is found that the equatorial Atlantic precipitation is reduced (increased) during El Niño (La Niña) in the case where the interannual variability of the equatorial Atlantic SST is disabled. The precipitation anomalies in the equatorial Atlantic during ENSO are not strongly associated with the meridional migration of the Atlantic inter-tropical convergence zone. We find the reduced precipitation in the equatorial Atlantic during El Niño is associated with an enhanced Atlantic Walker circulation characterized by strengthened low-level easterlies and anomalous dry, downward winds over the equatorial Atlantic, while the Pacific Walker circulation is weakened. The upper-level anomalous westerlies over the equatorial Atlantic are consistent with a Matsuno-Gill-type response to heating in the eastern equatorial Pacific. Our results of the CGCM experiments suggest that changes to the Walker circulation induced by ENSO contribute significantly to changes in precipitation over the equatorial Atlantic.

Sasaki, Wataru; Doi, Takeshi; Richards, Kelvin J.; Masumoto, Yukio

2015-01-01

226

Sequence walkers: a graphical method to display how binding proteins interact with DNA or RNA sequences.  

PubMed Central

A graphical method is presented for displaying how binding proteins and other macromolecules interact with individual bases of nucleotide sequences. Characters representing the sequence are either oriented normally and placed above a line indicating favorable contact, or upside-down and placed below the line indicating unfavorable contact. The positive or negative height of each letter shows the contribution of that base to the average sequence conservation of the binding site, as represented 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 to a sequence to create a quantitative map of a complex genetic region. One can alter the sequence to quantitatively engineer binding sites. Database anomalies can be visualized by placing a walker at the recorded positions of a binding molecule and by comparing this to locations found by scanning the nearby sequences. The sequence can also be altered to predict whether a change is a polymorphism or a mutation for the recognizer being modeled. PMID:9336476

Schneider, T D

1997-01-01

227

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

228

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

PubMed Central

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

Weiss, H. B.

1996-01-01

229

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

230

An appraisal of the water resources of the Walker River Indian Reservation, Nevada  

USGS Publications Warehouse

Increasing interest in expanding the livestock and agricultural operations on the Walker River Indian Reservation, Nev., has prompted the Walker River Paiute Tribe to have the present and available water resources of the reservation appraised and proposed sites for new wells evaluated. Flow of the Walker River into the reservation averages about 113,000 acre-feet a year. Of this amount, about 42,000 acre-feet is used on the reservation, recharging the gound-water system and supplying irrigation water for alfalfa and pasture crops. The water quality of the river water is well suited for these purposes, and the possibility of expanding surface-water use exists. A mathematical model of the ground-water system was constructed to test various assumptions about recharge and discharge rates. The model generated water-level contours that agreed reasonably well with measured water levels, median deviation was 12 feet. With additional data , the model could be used in the future to test the feasibility of evapotranspiration salvage at the seven proposed sites for new stock and irrigation wells. The primary users of ground water on the reservation are phreatophytes and playa surfaces. They allow ground water to be lost to evaporation. About 19,000 acre-feet per year is lost through this mechanism. Domestic and livestock uses account for only about 250 acre-feet per year. Total recharge to the ground-water system amounts to about 30 ,000 acre-feet per year, and the possibility of more extensive use of ground water on the reservation exists. Quality of the ground water in most areas is suitable for all intended purposes. (USGS)

Schaefer, Donald H.

1980-01-01

231

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

Calabrò, F; Arcuri, T; Jinkins, J R

2000-04-01

232

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

NASA Astrophysics Data System (ADS)

The southern Walker Lane is a right-lateral shear zone in western Nevada and eastern California that accommodates ~25% (9.3 ± 0.2 mm/yr) of the relative motion between the Pacific and North American plates. The region is characterized by discontinuous NNW-trending right-lateral strike-slip faults, and NE-trending, down-to-the-NW normal faults. The late Quaternary cumulative slip across the southern Walker Lane is only 1/2 the observed regional current geodetic rate of right-lateral shear. In order to better understand the modern distribution of strain accumulation and release across this region, we established a dense network of 50 new and existing campaign GPS monuments (from MAGNET and other networks). GPS data were processed using GIPSY-OASIS software to obtain sub-cm precision locations. To determine a new regional crustal velocity field we combine data from surveys of entirely new monuments only instrumented in 2010 and 2011 with existing monuments that were first instrumented as early as 1994, and reoccupied in 2010/11. We will report on initial velocity results for campaigns through 2011. As well, we will report on our successes with using the determined velocities in a modern regional block model (Meade and Loveless, BSSA 2009) to determine slip rates on individual faults in the southern Walker Lane. Elucidating slip on individual structures allows for a better accounting of slip across the region, and helps reveal distributed deformation that may not be preserved in the geologic record. These new results have important implications for the temporal and spatial distribution of strain accumulation and release along this portion of an evolving plate boundary.

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

2011-12-01

233

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

234

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

PubMed

Here we have prepared a series of ester compounds of obacunone, a naturally occurring limonoid, isolated from plants such as Citrus and Dictamnus angustifolius. Their insecticidal activity was evaluated at 1mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. When obacunone reacted with NaBH4, the ratio of two reduction products, C7?-hydroxyobacunone (2) and C7?-hydroxyobacunone (3), was related to the reaction mixing solvents. C7?-Propionyloxybacunone (4b) and C7?-(n)heptanoyloxybacunone (5g) exhibited the more promising insecticidal activity than their precursor obacunone and toosendanin. PMID:25465171

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

2014-11-15

235

Regional patterns of surface wind change over the tropical Indo-Pacific: Evidence of the Walker circulation slowdown  

NASA Astrophysics Data System (ADS)

A strong linkage between changes in the Walker circulation and tropical sea surface temperature (SST) is evident in satellite observations. For instance, a strengthening of the Walker circulation is observed by satellite wind measurements in recent decades, accompanied by intensified zonal SST and sea level height gradients. On the other hand, climate models predict that the Walker circulation slows down in response to global warming through hydrological cycle changes. We investigate these mechanisms for the observed Walker circulation changes over the last six decades, with a focus on physical consistency among surface wind, cloud, sea level pressure (SLP), subsurface ocean temperature, and SST. Our bias-corrected surface wind dataset displays westerly trends over the western tropical Pacific and easterly trends over the tropical Indian Ocean, indicative of a slowdown of the Walker circulation. This pattern of wind change is consistent with that of observed SLP change showing positive trends over the Maritime Continent and negative trends over the central equatorial Pacific. Suppressed moisture convergence over the Maritime Continent is largely due to surface wind changes, contributing to observed decreases in marine cloudiness and land precipitation there. Furthermore, observed ocean mixed layer temperatures indicate a reduction in zonal contrast in the tropical Indo-Pacific characterized by larger warming in the tropical eastern Pacific and western Indian Ocean than in the tropical western Pacific and eastern Indian Ocean. Similar changes are successfully simulated by an ocean general circulation model forced with the bias-corrected wind stress. Whereas results from major SST reconstructions show large uncertainty in zonal gradient in the tropical Indo-Pacific, both bucket-sampled SSTs and nighttime marine air temperatures show a weakening of the zonal gradient consistent with the subsurface temperature changes. All these findings from independent observations provide robust evidence for ocean-atmosphere coupling associated with the reduction in the Walker circulation over the last six decades.

Tokinaga, H.; Xie, S.; Timmermann, A.; McGregor, S.; Ogata, T.; Kubota, H.; Okumura, Y.

2012-12-01

236

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

PubMed Central

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

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

2014-01-01

237

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

238

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

239

Cenozoic evolution of the central Walker Lane Belt, west-central Nevada  

NASA Astrophysics Data System (ADS)

This dissertation is a collection of four papers that investigate deformation along the North America/Pacific plate boundary, geomagnetic field behavior, and aspects of volcanism in the western part of the Basin and Range Province. Active deformation along the America/Pacific plate boundary is distributed eastward across a wide zone of the western margin of the North American plate, from the San Andreas Fault eastward into the western Basin and Range province an area referred to as the Walker Lane Belt. Chapter three and four investigate aspects of deformation that has been transferred inboard of the continental plate boundary since the mid-Cenozoic inception of the system by investigating a key areas of the central Walker Lane Belt, west-central Nevada (Mina Deflection and southwest Silver Peak Range), where a significant component of the residual strain is being distributed. Deformation in these two areas is being accommodated along a system of late Cenozoic faults with strain partitioned into components of extension, strike slip faulting, and rotation of crustal blocks between the fault systems in the region. The results of this study allow for an assessment of late Tertiary deformation, which leads to a better understanding of the kinematics of deformation in this important part of the Walker Lane Belt. Chapter two investigates the transport direction of the Candelaria pyroclastic sequence by the anisotropy of magnetic susceptibility (AMS) technique. The AMS data are spatially variable across the region and indicate variable transport directions of the three regionally extensive ignimbrite deposits. The AMS fabric data indicate that the Candelaria pyroclastic sequence was erupted from distinct source areas likely separated by several kilometers. Chapter one investigates unusual geomagnetic field behavior at 25.7 Ma and 23.8 Ma preserved in volcanic rocks in the Mina Deflection. Paleomagnetic data indicate that parts of two transitional field records or reversal excursions are recorded. The observation that the virtual paleomagnetic poles (VGP) maintained a preferred location during separate high amplitude events supports the hypothesis that preferred VPG clusters and thus persistent non-dipole field components can factor into the behavior of the geomagnetic field during full reversals or reversal excursions.

Petronis, Michael S.

240

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 Walker’s 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

241

Species of the genus Aragara Walker (Diptera: Chloropidae: Chloropinae:
Mindini) from China with key to species of the world.
 

PubMed

The genus Aragara Walker is newly recorded from China. The following two species are described new to science: A. flavaristata sp. nov. and A. menglaensis sp. nov. One species, A. trilineata Cherian, is newly recorded from China, and one new combination, A. sinensis (Yang & Yang), is proposed. A key to world species of genus Aragara is given.  PMID:25543559

Liu, Xiaoyan; Yang, Ding

2014-01-01

242

11. PUBLICATIONS 2001-2002 Addis Tsehaye, Buchanan, A.H. & Walker, J.C.F. Selecting trees for structural  

E-print Network

Addis Tsehaye, Buchanan, A.H. & Walker, J.C.F. Sorting of boxed-pith lumber for stiffness. Journal the culverts gone? A GIS- based approach to finding stream-crossings. International Journal of Forest Engineering. 12(2) 2001: 79-81pp Douglas, R.A., & Cochrane, H. Where have all the culverts gone - a GIS

Hickman, Mark

243

Impact of Favorite Stimuli Automatically Delivered on Step Responses of Persons with Multiple Disabilities during Their Use of Walker Devices  

ERIC Educational Resources Information Center

Favorite stimuli were automatically delivered contingent on the performance of steps by two persons (a boy and a woman) with multiple disabilities during their use of support walker devices. The study lasted about 4 months and was carried out according to a multiple baseline design across participants. Recording concerned the participants'…

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

2005-01-01

244

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

Microsoft Academic Search

Favorite stimuli were automatically delivered contingent on the performance of steps by two persons (a boy and a woman) with multiple disabilities during their use of support walker devices. The study lasted about 4 months and was carried out according to a multiple baseline design across participants. Recording concerned the participants’ frequencies of steps and their indices of happiness during

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

2005-01-01

245

Integrating Einstein Field Equations in Observational Coordinates with Cosmological Data Functions: Nonflat Friedmann-Lemaître-Robertson-Walker Cases  

NASA Astrophysics Data System (ADS)

In this paper we use the integration scheme for the exact spherically symmetric Einstein field equations in observational coordinates recently developed by Araújo and Stoeger, and input data functions for area distance and galaxy number counts that would be obtained if the universe were exactly represented by nonflat Friedmann-Lemaître-Robertson-Walker models.

Araújo, M. E.; Arcuri, R. C.; Bedran, M. L.; de Freitas, L. R.; Stoeger, W. R.

2001-03-01

246

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

ERIC Educational Resources Information Center

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

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

2009-01-01

247

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

248

"It's Not so Much a Job but a Relationship": A Response to Romer and Walker  

ERIC Educational Resources Information Center

Romer and Walker's "Appreciative Inquiry," which obtained input from 16 capable personal assistants, challenges some influential assumptions about personal assistance and opens a way to think about the demanding work of developing capable and committed personal assistants. Attempts to depersonalize the relationship between people…

O'Brien, John

2013-01-01

249

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

ERIC Educational Resources Information Center

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

Strully, Jeffrey L.

2013-01-01

250

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

E-print Network

. The Entertainment Software Association estimates that computer and video game software sales in 2006 were $7 of machine learning and artificial intelligence, much of the technology used in games was de- velopedDatabase Research Opportunities in Computer Games Walker White, Christoph Koch, Nitin Gupta

Gehrke, Johannes

251

July 7, 2004 Safety Meeting Minutes Present; Thea Smith, Faith Cole, Randy Walker, Sean Matson and Lori Parker  

E-print Network

a safety and health point of view. It was noted that Ann Byar from NOAA's Safety Division had lab Safety. It is NOAA and OSU policy that they not be worn in the labs. Next month there will be a safety walk throughJuly 7, 2004 Safety Meeting Minutes Present; Thea Smith, Faith Cole, Randy Walker, Sean Matson

252

3D Pose Tracking of Walker Users' Lower Limb with a Structured-Light Camera on a Moving Platform  

E-print Network

Tracking and understanding human gait is an important step towards improving elderly mobility and safety. Specifically for the walker, the tracking system allows assessment and monitoring of gait, such as recovery tracking systems used for biomedical purposes. The best measurements currently available for gait

Poupart, Pascal

253

Changes in nutrient distribution in forests and soils of Walker Branch watershed, Tennessee, over an eleven-year period  

Microsoft Academic Search

Changes in vegetation, litter, and soil nutrient content were measured in selected plots on Walker Branch watershed, Tennessee, from 1972–73 to 1982. The watershed has been allowed to revert to forest since 1942, before which it consisted of small subsistence farms and woodland pastures. Changes in Ca status were of particular interest because initial nutrient cycling characterizations indicated that net

Dale W. Johnson; Gray S. Henderson; Donald E. Todd

1988-01-01

254

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

Microsoft Academic Search

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

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

2006-01-01

255

Spin-axis relaxation in spin-exchange collisions of alkali-metal atoms S. Kadlecek and T. Walker  

E-print Network

Spin-axis relaxation in spin-exchange collisions of alkali-metal atoms S. Kadlecek and T. Walker October 2000; published 18 April 2001 We present calculations of spin-relaxation rates of alkali-metal atoms due to the spin-axis interaction acting in binary collisions between the atoms. We show

Walker, Thad G.

256

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

Microsoft Academic Search

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

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

2005-01-01

257

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

USGS Publications Warehouse

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

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

2014-01-01

258

Ensemble member generation for sequential data assimilation M.R.J. Turner a,, J.P. Walker a  

E-print Network

Ensemble member generation for sequential data assimilation M.R.J. Turner a,, J.P. Walker a , P: Ensemble member generation; Sequential data assimilation; Ensemble filtering; Hydrodynamic modelling covariance extends linear sequential data assimilation schemes to nonlinear applications. This approach forms

Oke, Peter

259

High Quality Graphene Formation on Improved 3C-SiC Epilayer Michael Walker,1,2  

E-print Network

UG-32 High Quality Graphene Formation on Improved 3C-SiC Epilayer Michael Walker,1 on Si substrate. However, the graphene formed from the GOS suffers from mediocre quality. Aiming at the betterment of this process, we investigate the influence of the SiC layer quality on graphene. In this study

260

Promoting ambulation responses among children with multiple disabilities through walkers and microswitches with contingent stimuli.  

PubMed

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 stimuli to promote ambulation with these children. This study served as a replication of the aforementioned research and involved five new children with multiple disabilities. For four children, the study involved an ABAB design. For the fifth child, only an AB sequence was used. All children succeeded in increasing their frequencies of step responses during the B (intervention) phase(s) of the study, although the overall frequencies of those responses varied largely across them. These findings support the positive evidence already available about the effectiveness of this intervention approach in motivating and promoting children's ambulation. Practical implications of the findings are discussed. PMID:20207105

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

261

The Hadamard Condition for Dirac Fields and Adiabatic States on Robertson-Walker Spacetimes  

E-print Network

We characterise the homogeneous and isotropic gauge invariant and quasifree states for free Dirac quantum fields on Robertson-Walker spacetimes in any even dimension. Using this characterisation, we construct adiabatic vacuum states of order $n$ corresponding to some Cauchy surface. We then show that any two such states (of sufficiently high order) are locally quasi-equivalent. We propose a microlocal version of the Hadamard condition for spinor fields on arbitrary spacetimes, which is shown to entail the usual short distance behaviour of the twopoint function. The polarisation set of these twopoint functions is determined from the Dencker connection of the spinorial Klein-Gordon operator which we show to equal the (pull-back) of the spin connection. Finally it is demonstrated that adiabatic states of infinite order are Hadamard, and that those of order $n$ correspond, in some sense, to a truncated Hadamard series and will therefore allow for a point splitting renormalisation of the expected stress-energy tensor.

S Hollands

1999-06-17

262

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

PubMed

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

Mikhailov, Mikhail D; Freire, Atila P Silva

2014-12-01

263

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

E-print Network

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

Pierre Degond; Sébastien Motsch

2007-10-26

264

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

2009-07-03

265

Distance-Redshift in Inhomogeneous $Omega_0=1$ Friedmann-Lemaitre-Robertson-Walker Cosmology  

E-print Network

Distance--redshift relations are given in terms of associated Legendre functions for partially filled beam observations inspatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmologies. These models are dynamically pressure-free, flat FLRW on large scales but, due to mass inhomogeneities, differ in their optical properties. The partially filled beam area-redshift equation is a Lame$^{\\prime}$ equation for arbitrary FLRW and is shown to simplify to the associated Legendre equation for the spatially flat, i.e. $\\Omega_0=1$ case. We fit these new analytic Hubble curves to recent supernovae (SNe) data in an attempt to determine both the mass parameter $\\Omega_m$ and the beam filling parameter $\

R. Kantowski; R. C. Thomas

2001-06-18

266

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

PubMed

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

Liu, Guangfu; Xu, Yipeng; Yu, Xiaoping

2014-11-01

267

Seasonal nutrient dynamics of foliage and litterfall on Walker Branch Watershed, a deciduous forest ecosystem  

SciTech Connect

A detailed twelve-month study of litterfall, live foliage biomass, and seasonal nutrient (nitrogen, phosphorus, potassium, calcium, sodium, and magnesium) dynamics in tree components was performed for forest types on Walker Branch Watershed, Oak Ridge, Tennessee. Biomass and nutrient content of foliage, reproductive parts and branches were examined for ten dominant trees in order to assess the relative importance of litterfall in returning nutrients to the forest floor in four different forest types. Litterfall, measured in pine, pine-oak-hickory, oak-hickory, and mesophytic hardwood forests, was separated into three components (leaves, reproductive parts, and branches). Seasonal comparisons of those forest types were made for biomass and nutrient inputs for each component and for total litterfall.

Grizzard, T.; Henderson, G.S.; Clebsch, E.E.C.; Reichle, D.E.

1976-03-01

268

Emergence of space and spacetime dynamics of Friedmann-Robertson-Walker universe  

NASA Astrophysics Data System (ADS)

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

Cai, Rong-Gen

2012-11-01

269

Effects of field interactions upon particle creation in Robertson-Walker universes  

NASA Technical Reports Server (NTRS)

Particle creation due to field interactions in an expanding Robertson-Walker universe is investigated. A model in which pseudoscalar mesons and photons are created as a result of their mutual interaction is considered, and the energy density of created particles is calculated in model universes which undergo a bounce at some maximum curvature. The free-field creation of non-conformally coupled scalar particles and of gravitons is calculated in the same space-times. It is found that if the bounce occurs at a sufficiently early time the interacting particle creation will dominate. This result may be traced to the fact that the model interaction chosen introduces a length scale which is much larger than the Planck length.

Birrell, N. D.; Davies, P. C. W.; Ford, L. H.

1980-01-01

270

Changes in the Walker and Hadley circulations associated with the Southern Annular Mode  

NASA Astrophysics Data System (ADS)

Extratropical impacts on tropical climates are one of the most exciting areas of meteorological investigation in recent times. The present study elucidates the seasonal impact of the Southern Annular Mode (SAM) on predominant tropical circulations such as Hadley and Walker. The velocity potential at 200 hPa is used to understand the spatio-temporal variability in tropical circulations in the boreal summer and winter seasons. The results show an intensification of seasonal velocity potential in the composite of the low phase of the SAM. The seasonal climatological values of velocity potential observed for the period from 1979 to 2012 are of lesser magnitudes than earlier findings. The convergence/divergence locations of tropical circulation have shifted from their mean positions in the alternative phase of the SAM. The low-level convergence in the southern hemispheric Hadley circulation (HC) is enhanced in the composite of the positive phase of the SAM; however, the SAM's effect on the HC is no stronger in the summer. Another interesting feature noted in the present study is the weakening of the Walker circulation associated with the positive phase of the SAM, which can influence the basic state of the tropical Pacific Ocean. The SAM's interannual variability exhibits a significant positive trend in winter. The study reveals that the positive phase of the SAM could be a possible explanation for the recent changes in the tropical circulation patterns; however, the variability in tropical circulation anomalies associated with the SAM should be noted on seasonal and monthly scales to understand the dynamical mechanism behind the relationship. The impact of the SAM on tropical circulation may continue in future decades, as this southern extratropical vacillation is predicted to remain in a positive phase due to the increase in greenhouse gases and the variability in ozone.

Viswambharan, Nithin; Mohanakumar, K.

2014-08-01

271

Diagnosis of a case of Dandy-Walker malformation aided by measurement of the brainstem-vermis angle at 14 weeks gestation.  

PubMed

Reported is a fetal Dandy-Walker malformation that was strongly suspected in the first trimester through measurement of the brainstem-vermis (B-V) angle, which was found to be 119° on transvaginal ultrasound examination at 14 weeks and 2 days gestation. Definitive diagnosis of the Dandy-Walker malformation was made by magnetic resonance imaging following stillbirth. Ultrasound measurement of the B-V angle may be a useful index for prenatal diagnosis of Dandy-Walker anomalies during early pregnancy. PMID:25490874

Ichizuka, Kiyotake; Mishina, Miyuki; Hasegawa, Junichi; Matsuoka, Ryu; Sekizawa, Akihiko; Pooh, Ritsuko K

2014-12-10

272

Comparison of geologically-averaged paleomagnetic and "instantaneous" GPS rotation data in the West-Central Walker Lane  

NASA Astrophysics Data System (ADS)

The Walker Lane belt is a highly tectonically active region of dextral shear in western North America. Situated between the margins of the Sierra Nevada microplate and the Basin and Range extension, it extends northward from the Garlock Fault into portions of Southern Oregon. The Walker Lane is characterized by dextral shear accommodated by strike slip faults and left-stepping normal faults (Unruh et al, 2003). Faulting in the Walker Lane accounts for approximately 25% of the relative motion between the North American and Pacific Plates (Reheis and Dixon 1996). The study spans a region where the Sierra Nevada microplate has shed fault-bounded blocks from its eastern margin into the central Walker Lane during the Neogene. These blocks have behaved somewhat independently of one another and the Sierra Nevada as evidenced by spatially-variable magnitudes of vertical-axis rotation. This blurs the boundary of definition between microplate and fault block. One of the key questions regarding Walker Lane deformation is what is the role of rotation with respect to fault blocks and at what rate(s) does rotation occur. The software package SSPX (Cardozo and Allmendinger 2009) is used to examine previously published geodetic data to derive rotation rates in the west-central Walker Lane. A rate of 1.70° ± 0.24°/Ma is determined for Bridgeport Valley, CA based upon strain inversion of the locally-sparse GPS station data in SSPX. This rate is consistent with paleomagnetically-determined rotation rates for ~9.4 Ma members of the Stanislaus Group around Bridgeport Valley, adjacent to the Mina Deflection (e.g. King et al, 2007 and our data). However there are several shortcomings to using currently available GPS data for this purpose. GPS station spacing in many places does not provide spatial resolution of rotation comparable to the paleomagnetic dataset, which in turn limits our ability to examine small lithospheric fault blocks geodetically. The paleomagnetic data shows rotation variations on the scale of <5 km. Thus, due to GPS station spacing, our strain inversion reveals a spatially-averaged rotation for a larger given area and is not able to detect small lithospheric blocks or groups of blocks with anomalously large rotation rates of 7°/Ma or higher. An alternative hypothesis is that rotation rate is variable with time and that large rotations occurred and have slowed or stopped.

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

2011-12-01

273

Late Pleistocene displacement and slip rate for the Breckenridge fault, Walker Basin, southern Sierra Nevada, California  

NASA Astrophysics Data System (ADS)

The north-striking Breckenridge fault occurs along the 11-km-long western margin of Walker Basin, a west-tilted intermontane alluvial basin in the southern Sierra Nevada. This east-dipping normal fault has prominent geomorphic expression in the form of east-facing fault scarps on alluvial-fan deposits and distinct triangular facets of granitic bedrock along the range front. Steep, east-draining valleys are incised into bedrock west of the fault and are associated with inset or overlapping alluvial fan surfaces east of the fault. Detailed analysis of lidar-derived digital elevation models (DEMs) and field geomorphic mapping suggest that a 2-km-wide series of small right-stepovers separate the Breckenridge fault from the Holocene-active Kern Canyon fault to the north. Directly south of Walker Basin, prominent geomorphic expression of the Breckenridge fault dies out in an area of complex and distributed microseismicity, suggesting that the fault does not connect with the active White Wolf fault to the south. Herein, on the basis of geologic and geomorphic mapping, DEM interpretation, and cosmogenic radionuclide (CRN) dating, we report the first documented evidence for late Pleistocene normal faulting on the Breckenridge fault. At the Oak Tree site (38.431N, 118.545W), two alluvial-fan deposits (Qf1 and Qf3) exhibit east-down normal fault displacement. The active channel is entrenched about 8 and 14 m below these abandoned surfaces. Topographic profiles generated from DEMs along the extensive Qf1 and Qf3 surfaces show that fault scarp heights are progressively lower on younger surfaces. The oldest surface (Qf1) shows vertical separation of ~7 m, and the intermediate Qf3 surface exhibits ~4 m of vertical separation. The next youngest surface (Qf4) appears undeformed across the fault trace. Samples from granitic boulders exposed on the Qf1, Qf3, and Qf4 surfaces were collected for 10Be exposure dating. The CRN dates are consistent with stratigraphic position and yield ages (assuming zero inheritance and no erosion) of 68 ± 7 ka (1 sigma, n=3) for Qf1, 35 ± 2 ka (1 sigma, n=3) for Qf3, and 12 ± 2 ka (1 sigma, n=3) for Qf4. Using measured vertical separations, these data provide preliminary average late Pleistocene slip rates for the Breckenridge fault of ~0.1 mm/yr over ~68 and ~35 ky timescales. These data permit a relatively constant slip rate for the late Pleistocene on the Breckenridge fault that is lower than the Kern Canyon fault to the north. In addition, the 12 ± 2 ka age of the apparently undeformed Qf4 surface constrains the minimum age for the most-recent surface deformation and is consistent with the absence of fault scarps across young alluvial fan surfaces along most of the range front. These ages confirm previous analyses suggesting that the Breckenridge fault has controlled Quaternary deposition in the Walker Basin, and shows that the east-down normal displacement has continued to at least 35 ka and possibly 12 ka.

Brossy, C. C.; Baldwin, J. N.; Kelson, K. I.; Rood, D. H.; Kozlowicz, B.; Simpson, D.; Ticci, M.; Amos, C. B.; Kozaci, O.; Lutz, A.

2010-12-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

275

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

NASA Technical Reports Server (NTRS)

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

1953-01-01

276

Automatically Delivered Stimulation for Walker-Assisted Step Responses: Measuring its Effects in Persons with Multiple Disabilities  

Microsoft Academic Search

The present two studies evaluated the effects of automatically delivered stimulation for walker-assisted step responses with\\u000a four persons with multiple disabilities. In Study I, the participants (two children) wore two optic sensors at their heels,\\u000a which were activated by the performance of steps. Each sensor activation produced a 2.5-s stimulation during the intervention\\u000a and post-intervention periods. In Study II, the

Giulio E. Lancioni; Nirbhay N. Singh; Mark F. O’Reilly; Jeff Sigafoos; Doretta Oliva; Giorgia Piazzolla; Sara Pidala; Angela Smaldone; Francesco Manfredi

2007-01-01

277

The Einstein-Dirac Equation in Robertson-Walker Space-Time Does Not Admit Standard Solutions  

Microsoft Academic Search

The Einstein-Dirac equation is considered in the Robertson-Walker space-time. Solutions of the equation are looked for in\\u000a the class of standard solutions of the Dirac equation. It is shown that the Einstein-Dirac equation does not have standard\\u000a solutions for both massive and massless Dirac field. Also superpositions of massive standard solutions are not solutions of\\u000a the Einstein-Dirac equation. The result,

Antonio Zecca

2009-01-01

278

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

279

Gaussian approximation of lambdaphi/sup 4/ theory in (3+1)-dimensional spatially flat Robertson-Walker space  

SciTech Connect

We investigate lambdaphi/sup 4/ theory within the Gaussian approximation in spatially flat Robertson-Walker space in 3+1 dimensions. After having performed an adiabatic expansion for one of the ansatz functions, we find that the renormalization of the energy-momentum tensor provides two additional constraints which have to be satisfied by the bare couplings. These conditions force the theory to be trivial after renormalization.

Pohle, H.

1989-03-15

280

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

Microsoft Academic Search

In vertebrates, homologous recombinational repair (HRR) requires RAD51 and five RAD51 paralogs (XRCC2, XRCC3, RAD51B, RAD51C and RAD51D) that all contain conserved Walker A and B ATPase motifs. In human RAD51D we examined the require- ment for these motifs in interactions with XRCC2 and RAD51C, and for survival of cells in response to DNA interstrand crosslinks (ICLs). Ectopic expression of

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

2006-01-01

281

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

PubMed Central

A major challenge in interpreting the large volume of mutation data identified by next-generation sequencing (NGS) is to distinguish driver mutations from neutral passenger mutations to facilitate the identification of targetable genes and new drugs. Current approaches are primarily based on mutation frequencies of single-genes, which lack the power to detect infrequently mutated driver genes and ignore functional interconnection and regulation among cancer genes. We propose a novel mutation network method, VarWalker, to prioritize driver genes in large scale cancer mutation data. VarWalker fits generalized additive models for each sample based on sample-specific mutation profiles and builds on the joint frequency of both mutation genes and their close interactors. These interactors are selected and optimized using the Random Walk with Restart algorithm in a protein-protein interaction network. We applied the method in >300 tumor genomes in two large-scale NGS benchmark datasets: 183 lung adenocarcinoma samples and 121 melanoma samples. In each cancer, we derived a consensus mutation subnetwork containing significantly enriched consensus cancer genes and cancer-related functional pathways. These cancer-specific mutation networks were then validated using independent datasets for each cancer. Importantly, VarWalker prioritizes well-known, infrequently mutated genes, which are shown to interact with highly recurrently mutated genes yet have been ignored by conventional single-gene-based approaches. Utilizing VarWalker, we demonstrated that network-assisted approaches can be effectively adapted to facilitate the detection of cancer driver genes in NGS data. PMID:24516372

Jia, Peilin; Zhao, Zhongming

2014-01-01

282

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

PubMed Central

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

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

2012-01-01

283

VarWalker: personalized mutation network analysis of putative cancer genes from next-generation sequencing data.  

PubMed

A major challenge in interpreting the large volume of mutation data identified by next-generation sequencing (NGS) is to distinguish driver mutations from neutral passenger mutations to facilitate the identification of targetable genes and new drugs. Current approaches are primarily based on mutation frequencies of single-genes, which lack the power to detect infrequently mutated driver genes and ignore functional interconnection and regulation among cancer genes. We propose a novel mutation network method, VarWalker, to prioritize driver genes in large scale cancer mutation data. VarWalker fits generalized additive models for each sample based on sample-specific mutation profiles and builds on the joint frequency of both mutation genes and their close interactors. These interactors are selected and optimized using the Random Walk with Restart algorithm in a protein-protein interaction network. We applied the method in >300 tumor genomes in two large-scale NGS benchmark datasets: 183 lung adenocarcinoma samples and 121 melanoma samples. In each cancer, we derived a consensus mutation subnetwork containing significantly enriched consensus cancer genes and cancer-related functional pathways. These cancer-specific mutation networks were then validated using independent datasets for each cancer. Importantly, VarWalker prioritizes well-known, infrequently mutated genes, which are shown to interact with highly recurrently mutated genes yet have been ignored by conventional single-gene-based approaches. Utilizing VarWalker, we demonstrated that network-assisted approaches can be effectively adapted to facilitate the detection of cancer driver genes in NGS data. PMID:24516372

Jia, Peilin; Zhao, Zhongming

2014-02-01

284

Attractiveness-ratings of point-light-walkers - A new method to detect pedophilia in child molesters  

Microsoft Academic Search

pMeta-analysis and reviews on sexual recidivism consistently report thatsexual preference for children is one of the strongest predictors for reoffendingin child molesters. The aim of our study is to introduce a newpowerful implicit stimulus for the detection of sexual preference in childmolesters with and without the clinical diagnosis of paedophilia.During the early 1970s Gunnar Johansson (1973) introduced Point-Light-Walkers (PLWs) as

A. König; A. Schölmerich; N. F. Troje

2010-01-01

285

Ibuprofen-induced Walker 256 tumor cell death: cytochrome c release from functional mitochondria and enhancement by calcineurin inhibition  

Microsoft Academic Search

The participation of mitochondria in the mechanism of tumor cell death induced by non-steroid anti-inflammatory drugs is uncertain. Here we show that ibuprofen induces death of Walker 256 tumor cells independently on mitochondrial depolarization as estimated by flow cytometry using DioC6(3). Oligomycin increased mitochondrial transmembrane potential in both ibuprofen-treated and non-treated cells, indicating that ATP synthesis was sustained during cell

Claudia B. L. Campos; Giovanna R. Degasperi; Denise S. Pacífico; Luciane C. Alberici; Raquel S. Carreira; Fernando Guimarães; Roger F. Castilho; Anibal E. Vercesi

2004-01-01

286

Bicycle Helmet Wearing Is Not Associated with Close Motor Vehicle Passing: A Re-Analysis of Walker, 2007  

PubMed Central

Objectives To re-analyse bicycle overtaking data collected by Walker (2007) with a view to assess factors associated with close passing (<1 m), to adjust for other observed factors in a multivariable analysis, and to assess the extent to which the sample size in the original analysis may have contributed to spurious results. Method A re-analysis of 2,355 motor vehicle passing events recorded by Walker that includes information on cyclist's distance to the kerb, vehicle size and colour, city of observation, time of day, whether the event occurred while in a bikelane and helmet wearing. Each variable was considered for a final, multivariable model using purposeful selection of variables. The analysis was repeated using multiple logistic regression with passing distance dichotomised by the one metre rule. Bootstrap p-values were computed using sample sizes computed from conventional values of power and effect size. Results The previously observed significant association between passing distance and helmet wearing was not found when dichotomised by the one metre rule. Other factors were found to be significantly associated with close passing including cyclists' distance to the kerb, vehicle size and city of observation (Salisbury or Bristol, UK). P-values from bootstrap samples indicate the significance of helmet wearing resulted from an overly large sample size. Conclusions After re-analysis of Walker's data, helmet wearing is not associated with close motor vehicle passing. The results, however, highlight other more important factors that may inform effective bicycle safety strategies. PMID:24086528

Olivier, Jake; Walter, Scott R.

2013-01-01

287

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

PubMed

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

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

2014-02-01

288

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

PubMed

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

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

2014-03-01

289

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

290

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

NASA Astrophysics Data System (ADS)

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

Matyjasek, Jerzy; Sadurski, Pawe?

2013-11-01

291

Variability and symmetry of gait in early walkers with and without bilateral cerebral palsy  

PubMed Central

Purpose Investigating gait characteristics during the early stages of walking in CP may contribute to the understanding of the development of impaired gait. The objective of this study was to investigate differences in the variability and symmetry of spatiotemporal gait characteristics during the early years of walking in children with bilateral spastic CP compared to children with similar amounts of walking experience and typical development (TD). Methods The spatiotemporal gait parameters of 31 children (15 with spastic CP, 16 with TD) who had an average of 28.5 (18.1 SD) months of walking experience were collected using an instrumented walkway. Results All primary spatiotemporal parameters were reduced in the CP group, who also demonstrated greater stride-to-stride variability, compared to the TD group. There were no statistically significant differences in side-to-side symmetry between groups. Ankle dorsiflexion range of motion was related to several of the gait measures. Implications Clinical trials investigating gait interventions during the early years of walking in children with CP should be conducted to determine if treatment can reduce the functional limitations that are present during the emergence of walking skills. Further investigation should examine variability and symmetry in the kinematics, kinetics, and muscle activity patterns of early walkers with CP, and the effect of treatment on the variability and symmetry of walking characteristics. PMID:20338763

Prosser, Laura A.; Lauer, Richard T.; VanSant, Ann F.; Barbe, Mary F.; Lee, Samuel C.K.

2010-01-01

292

Weaker Walker Circulation during the Last Glacial Maximum due to reduced sea level  

NASA Astrophysics Data System (ADS)

The Last Glacial Maximum (LGM) -- a target climate interval for both proxy and model investigations -- provides an opportunity to test mechanisms that drive tropical climate change. Here, we present the first multi-proxy, multi-model synthesis of Indo-Pacific Warm Pool (IPWP) hydroclimate during the LGM. We collect precipitation and salinity proxy data and compare them to an ensemble of nine model simulations conducted as part of PMIP2 and PMIP3, employing a new semi-quantitative approach: the Cohen's ? statistic for categorical data comparison. We find that both the terrestrial and marine proxies -- which derive from completely independent archives -- record a coherent pattern of change that only one out of the nine models simulates correctly. This pattern is diagnostic of a mechanism involving the ascending branch of Walker circulation in the IPWP, and reflects the response of tropical circulation to the exposure of the Sunda Shelf due to lowered sea level. Our results implicate sea level as a first-order driver of tropical hydroclimate on glacial-interglacial timescales, and furthermore emphasize that changes in the tropical water cycle during the glacial times cannot be simply understood as a response to the "wet-get-drier" mechanism, which is the inverse of the "wet-get-wetter" mechanism for global warming. Our finding that the models simulate diverse responses to the Sunda Shelf exposure -- most of which do not agree with the proxies -- has major implications for our ability to simulate tropical climates both past and future.

Tierney, J. E.; Di Nezio, P. N.

2012-12-01

293

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

E-print Network

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

Stefano Mancini; Roberto Pierini; Mark M. Wilde

2014-05-11

294

A measure on the set of compact Friedmann-Lemaître-Robertson-Walker models  

NASA Astrophysics Data System (ADS)

Compact, flat Friedmann-Lemaître-Robertson-Walker (FLRW) models have recently regained interest as a good fit to the observed cosmic microwave background temperature fluctuations. However, it is generally thought that a globally, exactly flat FLRW model is theoretically improbable. Here, in order to obtain a probability space on the set F of compact, comoving, 3-spatial sections of FLRW models, a physically motivated hypothesis is proposed, using the density parameter ? as a derived rather than fundamental parameter. We assume that the processes that select the 3-manifold also select a global mass-energy and a Hubble parameter. The requirement that the local and global values of ? are equal implies a range in ? that consists of a single real value for any 3-manifold. Thus, the obvious measure over F is the discrete measure. Hence, if the global mass-energy and Hubble parameter are a function of 3-manifold choice among compact FLRW models, then probability spaces parametrized by ? do not, in general, give a zero probability of a flat model. Alternatively, parametrization by a spatial size parameter, the injectivity radius rinj, suggests the Lebesgue measure. In this case, the probability space over the injectivity radius implies that flat models occur almost surely (a.s.), in the sense of probability theory, and non-flat models a.s. do not occur.

Roukema, Boudewijn F.; Blanlœil, Vincent

2010-12-01

295

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

SciTech Connect

The authors are conducting a large-scale manipulative field experiment in an upland oak forest on the Walker Branch Watershed in eastern Tennessee to identify important ecosystem responses that might result from future precipitation changes. The manipulation of soil water content is being implemented by a gravity-driven transfer of throughfall from one 6400-m{sup 2} treatment plot to another. Throughfall is intercepted in {approx}1850 subcanopy troughs suspended above the forest floor of the dry plot and transferred by gravity flow across an ambient plot for subsequent distribution onto the wet treatment plot. Soil water content is being monitored at two depths with time domain reflectometers at 310 sampling locations across the site. The experimental system is able to produce statistically significant differences in soil water content in years having both dry and wet conditions. Maximum soil water content differentials between wet and dry plots in the 0- to 0.35-m horizon were 8 to 10% during summers with abundant precipitation and 3 to 5% during drought periods. Treatment impacts on soil water potential were restricted to the surface soil layer. Comparisons of pre- and post-installation soil and litter temperature measurements showed the ability of the experimental design to produce changes in soil water content and water potential without creating large artifacts in the forest understory environment.

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

1998-04-01

296

Behavior of Friedmann-Robertson-Walker Cosmological Models in Scalar-Tensor Gravity  

E-print Network

We analyze solutions to Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory, where a scalar field is coupled to gravity. Matter is modelled by a $\\gamma$-law perfect fluid, including false-vacuum energy as a special case. Through a change of variables, we reduce the field equations from fourth order to second order, and they become equivalent to a two-dimensional dynamical system. We then analyze the entire solution space of this dynamical system, and find that many qualitative features of these cosmologies can be gleaned, including standard non-inflationary or extended inflationary expansion, but also including bifurcations of stable or unstable expansion or contraction, noninflationary vacuum-energy dominated models, and several varieties of ``coasting," ``bouncing," ``hesitating," and ``vacillating" universes. It is shown that inflationary dogma, which states that a universe with curvature and dominated by inflationary matter will always approach a corresponding flat-space solution at late times, does not hold in general for the scalar-tensor theory, but rather that the occurence of inflation depends upon the initial energy of the scalar field relative to the expansion rate. In the case of flat space ($k=0$), the dynamical system formalism generates some previously known exact power-law solutions.

Shawn J. Kolitch; Douglas M. Eardley

1994-05-07

297

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

298

[Phases of the effect of the homeotic Walker mutation in the development of Drosophila melanogaster].  

PubMed

In this work, critical ontogenetic stages for wing traits affected by temperature-sensitive mutation Walker (Wk) were determined. The interaction between the Wk gene and some genes responsible for the cell-cycle control was studied. At various ontogenetic stages, the mutants were exposed to 17 degrees C for 12 h, and, at the beginning of oviposition, the fly age was registered. Nine types of wing abnormalities were classified. The temperature treatment during three developmental stages (12-24, 48-60, and 96-108 h) resulted in a decrease in normal wing number and a substantial increase in wing abnormalities. Different morphological types of imaginal disks were revealed: nondifferentiated disks, those lacking the notum region, and those with duplications of wing-forming regions. The allele-specific interaction between Wk and allele v27 of the Klp61F gene was also revealed. We suggest that gene Wk is a high-ranking gene in the system of genetic control of ontogeny, because the Wk mutation is manifested in numerous phenotypic variants both in the control and in the experiment and a complete set of these variants was observed at each developmental stage upon temperature treatment. The pleiotropic effect of the Wk gene on the formation of some Drosophila organs, including eyes and halters which are beyond the scope of this report, is in agreement with this suggestion. PMID:10779909

Furman, D P; Omel'ianchuk, L V

2000-03-01

299

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

PubMed

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

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

2013-02-01

300

Synthesis and insecticidal activity of new deoxypodophyllotoxin-based phenazine analogues against Mythimna separata Walker.  

PubMed

In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of new deoxypodophyllotoxin-based phenazine analogues modified in their E-ring were prepared, and their structures were well characterized by ¹H NMR, HRMS, ESI-MS, IR, optical rotation, and mp. The absolute steric configuration of one key isomer was unambiguously confirmed by X-ray crystallography. Their insecticidal activity was examined against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at the concentration of 1 mg/mL. All derivatives showed delayed insecticidal activity. Especially compound 9i, containing p-methoxybenzoylamnio at the C-9' position of deoxypodophyllotoxin-based phenazine fragment, exhibited the most promising insecticidal activity with the final mortality rate of 72.4%. According to the symptoms of the tested M. separata, the derivatives likely displayed an antimolting hormone effect. In addition, preliminary structure-activity relationships were observed. These suggested that the proper length of the side chain of alkylacylamino might be important for their insecticidal activity, and introduction of the acylamino groups at the C-9' position of deoxypodophyllotoxin-based phenazine fragment usually afforded more potent compounds than those containing the same ones at the C-10' position. This will pave the way for further design, structural modification, and development of deoxypodophyllotoxin-based derivatives as insecticidal agents. PMID:23756712

Wang, Juanjuan; Zhi, Xiaoyan; Yu, Xiang; Xu, Hui

2013-07-01

301

Corrected entropy of Friedmann-Robertson-Walker universe in tunneling method  

SciTech Connect

In this paper, we study the thermodynamic quantities of Friedmann-Robertson-Walker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by Banerjee and Majhi [25]. For this we first calculate the corrected Hawking-like temperature on apparent horizon by considering both scalar particle and fermion tunneling. With this corrected Hawking-like temperature, the explicit expressions of the corrected entropy of apparent horizon for various gravity theories including Einstein gravity, Gauss-Bonnet gravity, Lovelock gravity, f(R) gravity and scalar-tensor gravity, are computed. Our results show that the corrected entropy formula for different gravity theories can be written into a general expression (4.39) of a same form. It is also shown that this expression is also valid for black holes. This might imply that the expression for the corrected entropy derived from tunneling method is independent of gravity theory, spacetime and dimension of the spacetime. Moreover, it is concluded that the basic thermodynamical property that the corrected entropy on apparent horizon is a state function is satisfied by the FRW universe.

Zhu, Tao; Ren, Ji-Rong; Li, Ming-Fan, E-mail: zhut05@lzu.cn, E-mail: renjr@lzu.edu.cn, E-mail: limf07@lzu.cn [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)

2009-08-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

303

Increased thermal response to ultrasound in the Walker carcinosarcoma treated with vasoactive drugs  

SciTech Connect

In order to evaluate the potential of a highly selective Ca2+ entry blocker (nisoldipine) and of 5-hydroxytryptamine (5-HT) as adjuvant in hyperthermia treatment, we studied the differential flow response and time-course of tumor and normal tissue temperature following the administration of the two substances and during ultrasound heating. In 12 rats bearing Walker 256 carcinomas i.p. injection of 0.2-0.4 mg/kg nisoldipine caused a reduction in the tumor-to-muscle flow relationship of 4.4 +/- 1.9 (SD) to 1.74 +/- 0.86 as determined by intraarterial 133Xe injection; i.p. injection of 2-8 mg/kg 5-HT (N = 13) caused a respective reduction from 3.9 +/- 2.67 to 1.3 +/- 1.59. During a 20-min period of 41 degrees C normal tissue temperature-controlled ultrasound heating without drugs, tumor temperature attained 40.8 +/- 0.9 degrees C (N = 16). Nisoldipine or 5-HT injection at continuing 41 degrees C normal tissue temperature controlled energy delivery produced an instantaneous further increment of tumor temperature, eventually to 44.0 +/- 1.14 degrees C or 44.2 +/- 1.26 degrees C, respectively, after a period of 20 min. Injection of 0.9% NaCl (N = 4) solution caused only insignificant changes. Blood pressure and muscle perfusion were distinctly influenced by nisoldipine, but not by 5-HT. Since both drugs instantaneously increased the temperature differential between tumor and normal tissue, though by different vasoaction, they should be considered as adjuvants in hyperthermia.

Knapp, W.H.; Debatin, J.; Helus, F.; Sinn, H.J.; Ostertag, H.

1989-04-01

304

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

PubMed

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

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

2015-02-01

305

Paleomagnetic Data Bearing on the Eastern and Southern Boundaries of the Walker Lane Belt Transfer System  

NASA Astrophysics Data System (ADS)

In west-central Nevada, a transfer zone, which initiated in the mid-Miocene, presently links, via the Mina Deflection, right-lateral faults of the Eastern California Shear Zone to the south and the Central Nevada Seismic Belt and Walker Lane to the north. This transfer zone, the early inception of which is characterized by moderate (20-30°) clockwise crustal rotations previously identified (e.g., Candelaria Hills and surrounding ranges), along with right-lateral structures to the south and north, are part of a diffuse zone of intracontinental deformation that accommodates some 25 percent of the motion between the Pacific and North American plates. Although the northern and western boundaries of the transfer zone are relatively well defined by paleomagnetic data, the eastern and southeastern boundaries remain poorly constrained. Additional paleomagnetic data are being obtained from mid-to-late Tertiary volcanic rocks, presumably lying within (e.g., Montezuma Range, Palmetto Mountains, Monte Cristo Range) and outside (e.g., Goldfield Hills, San Antonio Mountains, Slate Ridge) of the transfer zone. Areas outside of the transfer zone are inferred to have not undergone any appreciable rotation since its inception. Volcanic rocks as well as shallow intrusions ranging in age from Oligocene to mid-Pliocene have been sampled (N=187) from inside and outside of the inferred southern and eastern boundaries of the transfer zone. Overall, the collection responds very favorably to progressive demagnetization; initial results are tentatively interpreted as suggesting the absence of appreciable rotation of the San Antonio Range (Tonopah, Nevada area and farther north). The extent to which areas near the eastern and southeastern boundaries have been rotated is under investigation. These data will aid in a better understanding of differential block rotation and tilting throughout the development of the west-central Nevada transfer system from the mid-Miocene to late Pliocene.

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

2007-12-01

306

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

PubMed Central

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

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

2013-01-01

307

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

PubMed Central

Both dogs and humans can be coinfected with various Ehrlichia, Bartonella, Rickettsia, and Babesia species. We investigated a kennel of sick Walker Hounds and their owners in southeastern North Carolina for evidence of tick-borne infections and associated risk factors. A high degree of coinfection was documented in the dog population. Of the 27 dogs, 26 were seroreactive to an Ehrlichia sp., 16 to Babesia canis, and 25 to Bartonella vinsonii, and 22 seroconverted to Rickettsia rickettsii antigens. According to PCR results, 15 dogs were infected with Ehrlichia canis, 9 with Ehrlichia chaffeensis, 8 with Ehrlichia ewingii, 3 with Ehrlichia equi, 9 with Ehrlichia platys, 20 with a Rickettsia species, 16 with a Bartonella species, and 7 with B. canis. The detection of DNA from any Ehrlichia species was associated with clinical illness and with concurrent B. canis infection (by PCR). Both E. canis and an uncharacterized Rickettsia species appeared to result in chronic or recurrent infection. Death in the dog population was associated with living in a dirt lot rather than the concrete kennel. Of 23 people on whom serologic testing was conducted, eight were seroreactive to Bartonella henselae, one to E. chaffeensis, and one to R. rickettsii antigen; however, none had clinical or hematologic abnormalities consistent with illness caused by these organisms. We conclude that kennel dogs with heavy tick exposure can be infected at a high rate with multiple, potentially zoonotic, tick-borne pathogens. In addition, our findings further illustrate the utility of PCR for documenting coinfection with tick-transmitted pathogens. PMID:10405413

Kordick, S. K.; Breitschwerdt, E. B.; Hegarty, B. C.; Southwick, K. L.; Colitz, C. M.; Hancock, S. I.; Bradley, J. M.; Rumbough, R.; Mcpherson, J. T.; MacCormack, J. N.

1999-01-01

308

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

SciTech Connect

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

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

1988-01-01

309

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

PubMed

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

Yang, Linlin; Wang, Shuxia; Li, Houhun

2014-01-01

310

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

PubMed

This review is dedicated to David Walker (1928-2012), a pioneer in the field of photosynthesis and chlorophyll fluorescence. We begin this review by presenting the history of light emission studies, from the ancient times. Light emission from plants is of several kinds: prompt fluorescence (PF), delayed fluorescence (DF), thermoluminescence, and phosphorescence. In this article, we focus on PF and DF. Chlorophyll a fluorescence measurements have been used for more than 80 years to study photosynthesis, particularly photosystem II (PSII) since 1961. This technique has become a regular trusted probe in agricultural and biological research. Many measured and calculated parameters are good biomarkers or indicators of plant tolerance to different abiotic and biotic stressors. This would never have been possible without the rapid development of new fluorometers. To date, most of these instruments are based mainly on two different operational principles for measuring variable chlorophyll a fluorescence: (1) a PF signal produced following a pulse-amplitude-modulated excitation and (2) a PF signal emitted during a strong continuous actinic excitation. In addition to fluorometers, other instruments have been developed to measure additional signals, such as DF, originating from PSII, and light-induced absorbance changes due to the photooxidation of P700, from PSI, measured as the absorption decrease (photobleaching) at about 705 nm, or increase at 820 nm. In this review, the technical and theoretical basis of newly developed instruments, allowing for simultaneous measurement of the PF and the DF as well as other parameters is discussed. Special emphasis has been given to a description of comparative measurements on PF and DF. However, DF has been discussed in greater details, since it is much less used and less known than PF, but has a great potential to provide useful qualitative new information on the back reactions of PSII electron transfer. A review concerning the history of fluorometers is also presented. PMID:23065335

Kalaji, Hazem M; Goltsev, Vasilij; Bosa, Karolina; Allakhverdiev, Suleyman I; Strasser, Reto J; Govindjee

2012-12-01

311

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

SciTech Connect

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

Dilles, J.H. (Oregon State Univ., Corvallis, OR (United States). Geosciences Dept.)

1993-04-01

312

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

PubMed

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

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

2014-06-15

313

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

PubMed

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

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

2005-01-01

314

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

PubMed

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

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

2014-12-15

315

Comment on 'Quantization of Friedmann-Robertson-Walker spacetimes in the presence of a negative cosmological constant and radiation'  

SciTech Connect

The quantization of the Friedmann-Robertson-Walker spacetime in the presence of a negative cosmological constant was used in a recent paper to conclude that there are solutions that avoid singularities (big bang-big crunch) at the quantum level. We show that a proper study of their model does not indicate that it prevents the occurrence of singularities at the quantum level, in fact the quantum probability of such event is larger than the classical one. Our numerical simulations based on the powerful variational sinc collocation method (VSCM) also show that the precision of the results of that paper is much lower than the 20 significant digits reported by the authors.

Amore, Paolo; Aranda, Alfredo; Cervantes, Mayra; Diaz-Cruz, J. L.; Fernandez, Francisco M. [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico) and Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima, Mexico Facultad de Ciencias Fisico-Matematicas, BUAP Apdo. Postal 1364, C.P.72000 Puebla, Pue (Mexico); INIFTA (Conicet, UNLP), Division Quimica Teorica, Diag. 113 y 64 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

2007-03-15

316

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

PubMed

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

Garcia, Claudia Moreira; Danni-Oliveira, Inês Moresco

2007-01-01

317

On the motion and geometry of the Sierra Nevada Great Valley micro-plate: Implications for Walker Lane tectonics  

NASA Astrophysics Data System (ADS)

The Sierra Nevada Great Valley (SNGV) micro-plate, a.k.a. the Fresno block, has long been recognized as a tectonically stable entity within the Pacific North America plate boundary zone. Some early geodetic studies have confirmed and defined its rigid behavior. However, those studies were based on a very limited amount of geodetic station velocities, and were unable to assess the extent of rigidity towards the edges of the block. The San Andreas and Garlock fault systems define the western and southern edges of the block, but no such features are readily recognizable to the north and east, along the Walker Lane belt. A better assessment of the location of the boundary or transition between the stable SNGV block and the Walker Lane is important for three reasons. It will provide a better understanding of what controls Walker Lane development and evolution, it will provide important boundary conditions in understanding the present-day kinematics of the Walker Lane, and it is contributes to the assessment of seismic hazard levels for the Reno-Carson City area. We analyze data from all the available GPS sites in the greater SNGV region, including data from the SCIGN, BARD and BARGEN networks, semi-continuous data from our own MAGNET network, and campaign-style data (e.g., USGS, SCEC). Also we have started to analyze regional PBO sites, however time-series for most of those sites are at present too short to infer reliable velocity estimates. We use the GIPSY OASIS II software which employs precise point positioning using dual-frequency carrier phase and pseudorange data, and the precise orbit, clock, and reference frame transformation products publicly available from JPL. The analysis includes carrier phase ambiguity resolution and regional filtering. Using these velocities we perform a kinematic analysis of the station velocity solution, solving for an angular velocity that best describes the motion of the SNGV. We analyze the residuals to investigate where the SNGV borders lie and how deviations from block behavior relate to fault systems at the block boundary.

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

2006-12-01

318

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

PubMed

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

Abbasi, Bilal; Craig, Walter

2014-09-01

319

The hydroxyl group of S685 in Walker A motif and the carboxyl group of D792 in Walker B motif of NBD1 play a crucial role for multidrug resistance protein folding and function  

PubMed Central

Structural analysis of MRP1-NBD1 revealed that the Walker A S685 forms hydrogen-bond with the Walker B D792 and interacts with magnesium and the ?-phosphate of the bound ATP. We have found that substitution of the D792 with leucine resulted in misfolding of the protein. In this report we tested whether substitution of the S685 with residues that prevent formation of this hydrogen-bond would also cause misfolding. Indeed, substitution of the S685 with residues potentially preventing formation of this hydrogen-bond resulted in misfolding of the protein. In addition, some substitutions that might form hydrogen-bond with D792 also yielded immature protein. All these mutants are temperature-sensitive variants. However, these complex-glycosylated mature mutants prepared from the cells grown at 27 °C still significantly affect ATP binding and ATP-dependent solute transport. In contrast, substitution of the S685 with threonine yielded complex-glycosylated mature protein that is more active than the wild-type MRP1, indicating that the interaction between the hydroxyl group of 685 residue and the carboxyl group of D792 plays a crucial role for the protein folding and the interactions of the hydroxyl group at 685 with magnesium and the ?-phosphate of the bound ATP play an important role for ATP-binding and ATP-dependent solute transport. PMID:18088596

Yang, Runying; Scavetta, Robert; Chang, Xiu-bao

2010-01-01

320

Epidemic modeling with discrete-space scheduled walkers: extensions and research opportunities  

PubMed Central

Background This exploratory paper outlines an epidemic simulator built on an agent-based, data-driven model of the spread of a disease within an urban environment. An intent of the model is to provide insight into how a disease may reach a tipping point, spreading to an epidemic of uncontrollable proportions. Methods As a complement to analytical methods, simulation is arguably an effective means of gaining a better understanding of system-level disease dynamics within a population and offers greater utility in its modeling capabilities. Our investigation is based on this conjecture, supported by data-driven models that are reasonable, realistic and practical, in an attempt to demonstrate their efficacy in studying system-wide epidemic phenomena. An agent-based model (ABM) offers considerable flexibility in extending the study of the phenomena before, during and after an outbreak or catastrophe. Results An agent-based model was developed based on a paradigm of a 'discrete-space scheduled walker' (DSSW), modeling a medium-sized North American City of 650,000 discrete agents, built upon a conceptual framework of statistical reasoning (law of large numbers, statistical mechanics) as well as a correct-by-construction bias. The model addresses where, who, when and what elements, corresponding to network topography and agent characteristics, behaviours, and interactions upon that topography. The DSSW-ABM has an interface and associated scripts that allow for a variety of what-if scenarios modeling disease spread throughout the population, and for data to be collected and displayed via a web browser. Conclusion This exploratory paper also presents several research opportunities for exploiting data sources of a non-obvious and disparate nature for the purposes of epidemic modeling. There is an increasing amount and variety of data that will continue to contribute to the accuracy of agent-based models and improve their utility in modeling disease spread. The model developed here is well suited to diseases where there is not a predisposition for contraction within the population. One of the advantages of agent-based modeling is the ability to set up a rare event and develop policy as to how one may mitigate damages arising from it. PMID:19922684

2009-01-01

321

Not too fast, but not too slow: searching strategies to beat a majority group of interacting walkers  

E-print Network

We introduce a model of interacting random walkers on a finite one-dimensional chain with absorbing boundaries or targets at the ends. Walkers are of two types: informed particles that move ballistically towards a given target, and diffusing uniformed particles that are biased towards close informed particles. This model mimics the dynamics of animals searching for food, where an informed individual knows the location of a food target and tries to persuade close-by uninformed conspecifics to go to that target. We characterize the success of this persuasion by the first-passage probability of the uniformed particle to the target, and we interpret the speed of the informed particle as a strategic parameter that the particle tunes to maximize its success. We find that the success probability is non-monotonic, reaching its maximum at an intermediate speed that increases with the diffusing rate of the uniformed particle. When two different groups of informed particles traveling in opposite directions compete, usua...

Martinez-Garcia, Ricardo; Vazquez, Federico

2014-01-01

322

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

SciTech Connect

In vertebrates, homologous recombinational repair (HRR) requires RAD51 and five RAD51 paralogs (XRCC2, XRCC3, RAD51B, RAD51C, and RAD51D) that all contain conserved Walker A and B ATPase motifs. In human RAD51D we examined the requirement for these motifs in interactions with XRCC2 and RAD51C, and for survival of cells in response to DNA interstrand crosslinks. Ectopic expression of wild type human RAD51D or mutants having a non-functional A or B motif was used to test for complementation of a rad51d knockout hamster CHO cell line. Although A-motif mutants complement very efficiently, B-motif mutants do not. Consistent with these results, experiments using the yeast two- and three-hybrid systems show that the interactions between RAD51D and its XRCC2 and RAD51C partners also require a functional RAD51D B motif, but not motif A. Similarly, hamster Xrcc2 is unable to bind to the non-complementing human RAD51D B-motif mutants in co-immunoprecipitation assays. We conclude that a functional Walker B motif, but not A motif, is necessary for RAD51D's interactions with other paralogs and for efficient HRR. We present a model in which ATPase sites are formed in a bipartite manner between RAD51D and other RAD51 paralogs.

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

2006-04-21

323

Chronic supplementation with shark liver oil for reducing tumor growth and cachexia in walker 256 tumor-bearing rats.  

PubMed

We investigated the effect of chronic supplementation with shark liver oil (SLO), an antitumor supplement source of n-3 fatty acids and 1-O-alkylglycerols, alone and combined with coconut fat (CF), a source of saturated fatty acids, on Walker 256 tumor growth and cachexia. Male rats were supplemented daily and orally with SLO and/or CF (1 g per kg body weight) for 7 wk. After 7 wk, 50% of animals were subcutaneously inoculated with 3 × 10(7) Walker 256 tumor cells. After 14 days, the rats were killed, the tumors were removed for lipid peroxidation measurement, and blood was collected for glycemia, triacylglycerolemia, and lacticidemia evaluation. Liver samples were obtained for glycogen measurement. Unlike CF, supplementation with SLO promoted gain in body weight, reduction of tumor weight, and maintained glycemia, triacylglycerolemia, lacticidemia, and liver glycogen content to values similar to non-tumor-bearing rats. Combined supplementation of SLO with CF also showed a reversion of cachexia with gain in body mass, reduction of lacticidemia, maintaining the liver glycogen store, and reduction in tumor weight. SLO, alone or combined with CF, promoted increase of tumor lipid peroxidation. In conclusion, SLO supplemented chronically, alone or associated with CF, was able to reduce tumor growth and cachexia. PMID:21981555

Iagher, Fabíola; de Brito Belo, Sérgio Ricardo; Naliwaiko, Katya; Franzói, Andressa Machado; de Brito, Gleisson Alisson Pereira; Yamazaki, Ricardo Key; Muritiba, Ana Lúcia; Muehlmann, Luis Alexandre; Steffani, Jovani Antonio; Fernandes, Luiz Cláudio

2011-11-01

324

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

NASA Astrophysics Data System (ADS)

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

Donald, Jonathon

325

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

SciTech Connect

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

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

1999-01-01

326

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

327

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

328

Effects of commercial insecticide treatments to winter oilseed rape on parasitism of Ceutorhynchus assimilis Paykull (Coleoptera: Curculionidae) by Trichomalus perfectus (Walker) (Hymenoptera: Pteromalidae)  

Microsoft Academic Search

Trichomalus perfectus (Walker) is the most widespread and abundant parasitoid attacking Ceutorhynchus assimilis Paykull, a major pest of winter oilseed rape, in Europe. In a 2-year study, the effects on T. perfectus of commercial applications of alphacypermethrin and of triazophos to control C. assimilis were investigated. Triazophos had a detrimental effect on T. perfectus. It was applied at the time

A. K. Murchie; I. H. Williams; D. V. Alford

1997-01-01

329

A Circuit Level Fault Model for Resistive Bridges ZHUO LI, XIANG LU, WANGQI QIU, WEIPING SHI and D. M. H. WALKER  

E-print Network

A Circuit Level Fault Model for Resistive Bridges ZHUO LI, XIANG LU, WANGQI QIU, WEIPING SHI and D. M. H. WALKER Texas A&M University Delay faults are an increasingly important test challenge. Modeling bridge faults as delay faults helps delay tests to detect more bridge faults. Traditional bridge

Walker, Duncan M. "Hank"

330

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

E-print Network

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

331

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

Microsoft Academic Search

The effect of coconut fat (rich in medium saturated fatty acids) or fish oil (rich in -3 polyunsaturated fatty acids) supplementation for 2 generations on tumor growth, cancer cachexia, animal survival and macrophage function was investigated in Walker 256 tumor-bearing rats. Female Wistar rats were supplemented with coconut fat or fish oil prior to mating and then throughout pregnancy and

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

2007-01-01

332

Can in situ methanogenesis explain a 3 m-thick gas hydrate-filled sand in Walker Ridge Block 313, Gulf of Mexico?  

Microsoft Academic Search

In the spring of 2009, the Gulf of Mexico Gas Hydrate Joint Industry Project (JIP) Leg II drilled several holes in the Gulf of Mexico in the search for gas hydrate-filled reservoirs. In Walker Ridge Block 313, Hole H was drilled in a location where the gas hydrate stability zone (GHSZ) extended over 800 meters below seafloor (mbsf). For this

A. Cook; A. Malinverno

2010-01-01

333

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

334

Diagnostic tardif d’un syndrome de Dandy-Walker révélé par des troubles de la marche chez le sujet âgé  

Microsoft Academic Search

The Dandy–Walker syndrome is a rare malformation usually diagnosed during pregnancy or early in the course of life. We report a case in an elderly hospitalised for gait disorders and recurrent falls. Cerebral MRI revealed hydrocephalus and posterior fossa cyst. The patient improved after ventriculocisternostomia.

D. Forestier; A. Listrat; M. Priner; A.-S. Gaubert; G. Kemoun; M. Paccalin

2008-01-01

335

Walker Gilmore: a stratified Woodland period occupation in eastern Nebraska. A report of the 1968 excavations. Final report 1968-83  

Microsoft Academic Search

Excavations at Walker Gilmore were designed to test the ill-defined concept of 'Sterns Creek culture' in the Central Plains subarea. Five Woodland period levels produced evidence for 48 tool classes, flora and fauna, and 762 features including structural remains. Level 1 is poorly recorded and relatively unknown. Levels 2 - 4 contain abundant evidence of subsistence, structure, and settlement. Broad

Haas

1983-01-01

336

EXCHANGE RESONANCES IN GADOLINIUM IRON GARNET AT 24.000 MHz By S. GESCHWIND, L. R. WALKER and D. F. LINN,  

E-print Network

344 EXCHANGE RESONANCES IN GADOLINIUM IRON GARNET AT 24.000 MHz By S. GESCHWIND, L. R. WALKER and D garnet at 24 000 Mc in the vicinity of the magnetic compensation point at Tc = + 13 °C. The two modes, F�VRIER-MARS 1959, Introduction. - The rare earth iron garnets are, strictly, systems with three

Paris-Sud XI, Université de

337

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

Microsoft Academic Search

Global Positioning System (GPS) data collected in campaigns in 2000 and 2004 were processed and interpreted with other GPS data in the western Basin and Range province to provide new constraints on the rate, style, and pattern of deformation of the central and northern Walker Lane (WL), which lies near the western boundary of the Basin and Range. Across the

William C. Hammond; Wayne Thatcher

2007-01-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

339

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

PubMed Central

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

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

2014-01-01

340

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

SciTech Connect

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

Constantin, M.; Mauffette, Y. (UQAM, GREF, C.P., Montreal, Quebec (Canada))

1993-06-01

341

Quantization of Friedmann-Robertson-Walker spacetimes in the presence of a negative cosmological constant and radiation  

SciTech Connect

In the present work, we quantize three Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and radiation. The models differ from each other by the constant curvature of their spatial sections, which may be positive, negative or zero. They give rise to Wheeler-DeWitt equations for the scale factor which have the form of the Schroedinger equation for the quartic anharmonic oscillator. We find their eigenvalues and eigenfunctions by using a method first developed by Chhajlany and Malnev. After that, we use the eigenfunctions in order to construct wave packets for each case and evaluate the time-dependent expectation value of the scale factors, which are found to oscillate between finite maximum and minimum values. Since the expectation values of the scale factors never vanish, we have an initial indication that these models may not have singularities at the quantum level.

Monerat, G.A.; Silva, E.V. Correa; Oliveira-Neto, G. [Departamento de Matematica e Computacao, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Estrada Resende-Riachuelo, s/no, Morada da Colina, CEP 27523-000, Resende-RJ (Brazil); Filho, L.G. Ferreira [Departamento de Mecanica e Energia, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Estrada Resende-Riachuelo, s/no, Morada da Colina, CEP 27523-000 , Resende-RJ (Brazil); Lemos, N.A. [Instituto de Fisica, Universidade Federal Fluminense, R. Gal. Milton Tavares de Souza s/no, Boa Viagem, CEP 24210-340, Niteroi-RJ (Brazil)

2006-02-15

342

ISPD loss-of-function mutations disrupt dystroglycan O-mannosylation and cause Walker-Warburg syndrome  

PubMed Central

Walker-Warburg syndrome (WWS) is clinically defined as congenital muscular dystrophy accompanied by a variety of brain and eye malformations. It represents the most severe clinical phenotype in a spectrum of alpha-dystroglycan posttranslational processing abnormalities, which share a defect in laminin binding glycan synthesis1. Although six WWS causing genes have been described, only half of all patients can currently be diagnosed genetically2. A cell fusion complementation assay using fibroblasts from undiagnosed WWS individuals identified five novel complementation groups. Further evaluation of one group by linkage analysis and targeted sequencing identified recessive mutations in the isoprenoid synthase domain containing (ISPD) gene. Confirmation of the pathogenicity of the identified ISPD mutations was demonstrated by complementation of fibroblasts with wild-type ISPD. Finally, we show that recessive mutations in ISPD abolish the initial step in laminin binding glycan synthesis by disrupting dystroglycan O-mannosylation. This establishes a novel mechanism for WWS pathophysiology. PMID:22522420

Willer, Tobias; Lee, Hane; Lommel, Mark; Yoshida-Moriguchi, Takako; de Bernabe, Daniel Beltran Valero; Venzke, David; Cirak, Sebahattin; Schachter, Harry; Vajsar, Jiri; Voit, Thomas; Muntoni, Francesco; Loder, Andrea S.; Dobyns, William B.; Winder, Thomas L.; Strahl, Sabine; Mathews, Katherine D.; Nelson, Stanley F.; Moore, Steven A.; Campbell, Kevin P.

2012-01-01

343

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

NASA Astrophysics Data System (ADS)

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

Biholar, Alexander Kenneth Casian

344

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

345

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

E-print Network

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

R. Kantowski

2003-08-24

346

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

PubMed

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

Takanokura, Masato

2010-03-22

347

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

NASA Astrophysics Data System (ADS)

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

Linder, Jacob; Alidoust, Mohammad

2013-08-01

348

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

PubMed

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

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

2013-01-01

349

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

NASA Astrophysics Data System (ADS)

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

Kell, Anna Marie

350

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

NASA Astrophysics Data System (ADS)

The Gulf of California (GC) and Walker Lane (WL) have undergone strikingly similar development with strike- slip faulting following initial extension. They differ significantly in the amount of Pacific-North American plate motion taken up by each: essentially all relative motion in the GC and ~25% in the WL. In both areas, ancestral arc magmatism preceded and probably focused deformation, perhaps because heating and/or hydration weakened the lithosphere. However, differences in migration of the Rivera (RTJ) and Mendocino triple junctions (MTJ) related to differences in the orientation of plate boundaries determined how strike-slip faulting developed. Abrupt southward jumps in the RTJ led to abrupt cessation of magmatism over arc lengths of as much as 1000 km and initiation of east-northeast extension within the future GC. The best known jump was at ~13 Ma, but an earlier jump occurred at ~18 Ma. Arc magmatism has been best documented in Baja California, Sonora, and Nayarit, although Baja constituted the most-trenchward fringe of the ancestral arc. New and published data indicate that Sinaloa underwent a similar history of arc magmatism. The greatest volume of the arc immediately preceding RTJ jumps was probably in mainland Mexico. Arc magmatism shut off following these jumps, extension began in the future GC, and strike-slip faulting either followed or accompanied extension in the GC. In contrast, the MTJ migrated progressively northward. New and published data indicate magmatism generally shut off coincident with this retreat, but distinct nodes or zones of magmatism, presumably unrelated to subduction, persisted or initiated after arc activity ceased. We have suggested that the WL has grown progressively northward, following the retreating arc, and that the northern WL is its youngest part. However, the timing of initiation of strike-slip faulting in most of the WL is poorly known and controversial. Testing our hypothesis requires determining initiation and magnitudes of total slip across different parts. Despite the progressive migration of the MTJ, arc magmatism ceased abruptly at the latitude of Lake Tahoe (39.2°) at about 3 Ma, and the southern end of the active Cascade arc jumped ~160 km northward to Lassen Peak (40.5°), where it remains. Geologic data indicate strike-slip faulting began between these two areas immediately following the end of arc magmatism. The southern Cascade arc is undergoing ~east-west extension, which was the case for the northern Walker Lane immediately before strike-slip faulting began. Further progression or steps in magmatism and strike-slip faulting will likely follow further northward migration of the MTJ.

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

2006-12-01

351

Role of highly central residues of P-loop and it's flanking region in preserving the archetypal conformation of Walker A motif of diverse P-loop NTPases  

PubMed Central

P-loop NTPases represent a large and highly diverse protein family that is involved in variety of cellular functions. Walker A motif forms a typical arched conformation, necessary to accommodate the phosphate moiety of the nucleoside tri (or di-) phosphate in Ploop NTPases. The feature that maintains the ancient architecture of P-loop is unidentified and uncharacterized. Here, using a well established global network parameter, closeness centrality, we identify that Walker A and its flanking regions (N- and C-terminal) have high density of globally connected residue positions. We find that closeness centrality of these residue positions are conserved across common structural core of diverse domains of P-loop NTPase fold. Our results suggest the potential role of globally connected residues in maintaining the local conformation of P-loop. PMID:23390340

Pathak, Ekta; Atri, Neelam; Mishra, Rajeev

2013-01-01

352

Role of highly central residues of P-loop and it's flanking region in preserving the archetypal conformation of Walker A motif of diverse P-loop NTPases.  

PubMed

P-loop NTPases represent a large and highly diverse protein family that is involved in variety of cellular functions. Walker A motif forms a typical arched conformation, necessary to accommodate the phosphate moiety of the nucleoside tri (or di-) phosphate in Ploop NTPases. The feature that maintains the ancient architecture of P-loop is unidentified and uncharacterized. Here, using a well established global network parameter, closeness centrality, we identify that Walker A and its flanking regions (N- and C-terminal) have high density of globally connected residue positions. We find that closeness centrality of these residue positions are conserved across common structural core of diverse domains of P-loop NTPase fold. Our results suggest the potential role of globally connected residues in maintaining the local conformation of P-loop. PMID:23390340

Pathak, Ekta; Atri, Neelam; Mishra, Rajeev

2013-01-01

353

Natural products-based insecticidal agents 4. Semisynthesis and insecticidal activity of novel esters of 2-chloropodophyllotoxin against Mythimna separata Walker in vivo.  

PubMed

By using podophyllotoxin as a lead compound, eight novel esters of 2-chloropodophyllotoxin were designed, semisynthesized, and preliminarily evaluated for their insecticidal activity against the pre-third-instar larvae of Mythimna separata Walker in vivo for the first time. Among all the tested compounds, especially three esters of 2-chloropodophyllotoxin 8a, 8c, and 8g, and one intermediate 6 showed more promising and pronounced insecticidal activity than toosendanin, a commercial insecticide derived from Melia azedarach. PMID:19665895

Xu, Hui; Xiao, Xiao

2009-09-15

354

Evolution and Strain Reorganization within Late Neogene Structural Stepovers Linking the Central Walker Lane and Northern Eastern California Shear Zone, Western Great Basin  

Microsoft Academic Search

Late Neogene deformation between the eastern Sierra Nevada and the central Basin and Range province is localized within a boundary zone that contains the Eastern California shear zone and Walker Lane, and has been characterized by dextral strike-slip to oblique-slip displacement on NNW- to northwest-trending fault systems. At the latitude of the central Sierra Nevada, structures in the northern Eastern

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

2008-01-01

355

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

USGS Publications Warehouse

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

Welch, Alan H.; Williams, Rhea P.

1987-01-01

356

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

E-print Network

postmodern philosophy and historical analysis energizes Law, Crime and English Society, 1660-1830, edited by Norma Landau, and Crime, Gender and Social Order in Early Modern England by Garthine Walker. While only the latter acknowledges its reviews 17... of postmodern thought: the rendering of all cultural production as ?texts? and ?discourses? that make equal claims to interpretive authority. In distinction to most post- modern work undertaken in literary studies, however, the two books anchor themselves...

Sherman, Donovan

2010-01-01

357

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

PubMed

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

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

2008-12-01

358

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

PubMed Central

Abstract The genus Tinissa Walker is reviewed for China. Seven species are recognized, of which Tinissa apicimaculata sp. n., Tinissa conchata sp. n., Tinissa connata sp. n.,Tinissa leguminella sp. n. and Tinissa spirella sp. n. are described as new; and Tinissa insularia Robinson, 1976 is newly recorded from China. Photographs of the adults and illustrations of the genitalia are given. A key to all the known Chinese species and a distribution map of Tinissa in China are included. PMID:23166467

Yang, Linlin; Li, Houhun

2012-01-01

359

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

E-print Network

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

Jennie D'Ambroise; Floyd L. Williams

2010-07-24

360

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

PubMed

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

Doolin, Ciaran; Neupane, Ishwaree P

2013-04-01

361

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

PubMed

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

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

2014-10-01

362

Cloning, Expression and Purification of Subunit H of Vacuolar H+-ATPase from Mythimna separata Walker (Lepidoptera: Noctuidae)  

PubMed Central

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

Lu, Lina; Qi, Zhijun; Wu, Wenjun

2014-01-01

363

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

PubMed Central

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

Lv, Min; Wu, Wenjun; Liu, Huixia

2014-01-01

364

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

SciTech Connect

This study described a modified rat model of bone cancer pain. Syngeneic Walker 256 mammary gland carcinoma cells were injected into the tibia medullary cavity via intercondylar eminence. Series of tests were carried out including bone radiology, bone histology, ambulatory pain, thermal hyperalgesia, mechanical allodynia, weight bearing ability, and electrophysiological recording from primary afferent fibers. The rats inoculated with carcinoma cells showed significant ambulatory pain, mechanical allodynia, and reduction in weight bearing, as well as increased incidence of spontaneous activity in A{beta} fibers in affected limb, whereas PBS (vehicle) or heat-killed cells (sham) injected rats showed no significant difference in comparison to normal rats. The pain hypersensitive behaviors were aggravated with time and destruction of bone. Interestingly, mechanical allodynia was also observed in the contralateral limb, indicating the involvement of 'mirror image' pain in bone cancer pain. In summary, the present study provided a useful and easily established rat model of bone cancer pain which will contribute to further study of the mechanisms underlying cancer pain.

Mao-Ying, Q.-L. [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Zhao Jun [Institute of Neurobiology, Fudan University, Shanghai 200433 (China); Dong Zhiqiang [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Wang Jun [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Yu Jin [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Yan Minfen [Institute of Radiation Medicine, Fudan University, Shanghai 200032 (China); Zhang Yuqiu [Institute of Neurobiology, Fudan University, Shanghai 200433 (China); Wu Gencheng [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Wang Yanqing [Department of Integrative Medicine and Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032 (China) and Shanghai Research Center of Acupuncture and Meridian, Shanghai 201203 (China)]. E-mail: wangyanqing@shmu.edu.cn

2006-07-14

365

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

PubMed

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

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

2013-02-01

366

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

367

In-stream biotic control on nutrient biogeochemistry in a forested sheadwater tream, West Fork of Walker Branch  

SciTech Connect

A growing body of evidence demonstrates the importance of in-stream processing in regulating nutrient export, yet the influence of temporal variability in stream metabolism on net nutrient uptake has not been explicitly addressed. Streamwater DIN and SRP concentrations in Walker Branch, a first-order deciduous forest stream in eastern Tennessee, show a repeated pattern of annual maxima in summer and biannual minima in spring and autumn. Temporal variations in catchment hydrologic flowpaths result in lower winter and higher summer nutrient concentrations, but do not explain the spring and autumn nutrient minima. Ambient nutrient uptake rates were measured 2-3 times per week over an 18-mo period and compared to daily rates of gross primary production (GPP) and ecosystem respiration (ER) to examine the influence of in-stream biotic activity on nutrient export. GPP and ER rates explained 85% of the variation in net DIN retention with high net NO3- uptake (and lower net NH4+ release) rates occurring during spring and autumn and net DIN release in summer. Diel nutrient concentration patterns were examined several times throughout the year to determine the relative importance of autotrophic and heterotrophic activity on net nutrient uptake. High spring GPP corresponded to daily decreases in NO3- over the illuminated hours resulting in high diel NO3- amplitude which dampened as the canopy closed. GPP explained 91% of the variance in diel NO3- amplitude. In contrast, the autumn nutrient minima was largely explained by heterotrophic respiration since GPP remained low and little diel NO3- variation was observed during the autumn.

Roberts, Brian J [ORNL; Mulholland, Patrick J [ORNL

2007-01-01

368

A Deletion in the VLDLR Gene in Eurasier Dogs with Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation (DWLM)  

PubMed Central

Dandy-Walker-like malformation (DWLM) is the result of aberrant brain development and mainly characterized by cerebellar hypoplasia. DWLM affected dogs display a non-progressive cerebellar ataxia. Several DWLM cases were recently observed in the Eurasier dog breed, which strongly suggested a monogenic autosomal recessive inheritance in this breed. We performed a genome-wide association study (GWAS) with 9 cases and 11 controls and found the best association of DWLM with markers on chromosome 1. Subsequent homozygosity mapping confirmed that all 9 cases were homozygous for a shared haplotype in this region, which delineated a critical interval of 3.35 Mb. We sequenced the genome of an affected Eurasier and compared it with the Boxer reference genome and 47 control genomes of dogs from other breeds. This analysis revealed 4 private non-synonymous variants in the critical interval of the affected Eurasier. We genotyped these variants in additional dogs and found perfect association for only one of these variants, a single base deletion in the VLDLR gene encoding the very low density lipoprotein receptor. This variant, VLDLR:c.1713delC is predicted to cause a frameshift and premature stop codon (p.W572Gfs*10). Variants in the VLDLR gene have been shown to cause congenital cerebellar ataxia and mental retardation in human patients and Vldlr knockout mice also display an ataxia phenotype. Our combined genetic data together with the functional knowledge on the VLDLR gene from other species thus strongly suggest that VLDLR:c.1713delC is indeed causing DWLM in Eurasier dogs. PMID:25668033

Gerber, Martina; Fischer, Andrea; Jagannathan, Vidhya; Drögemüller, Michaela; Drögemüller, Cord; Schmidt, Martin J.; Bernardino, Filipa; Manz, Eberhard; Matiasek, Kaspar; Rentmeister, Kai; Leeb, Tosso

2015-01-01

369

The natural history of Dandy-Walker syndrome in the United States: A population-based analysis  

PubMed Central

Background: Dandy-Walker syndrome (DWS) is a congenital disorder typically manifesting with hydrocephalus. The classic anatomic hallmarks of DWS are hypoplasia of the cerebellar vermis, anterior-posterior enlargement of the posterior fossa, upward displacement of the torcula and transverse sinuses, and cystic dilatation of the fourth ventricle. Aims: Although optimal treatment of DWS typically requires neurosurgical intervention to prevent intracranial pressure increases incompatible with life, the natural history of this disorder has yet to be evaluated on a nationwide level. Settings and Design/Materials and Methods: The Kids’ Inpatient Database covering 1997-2003 was used for analysis. Children younger than age 18 admitted for DWS (ICD-9-CM = 742.3) were analyzed with a matched control group. The primary procedure codes for operative CSF drainage were coded into the analysis. The incidence of DWS was 0.136%; 14,599 DWS patients were included. Statistical Analysis Used: Multiple logistic regression models were used. Odds ratios (OR) were reported with 95% confidence intervals. Results and Conclusions: Mortality (OR = 10.02; P < 0.0001) and adverse discharge disposition (OR = 4.59; P < 0.0001) were significantly greater in DWS patients compared with controls. 20.4% of DWS patients received operative cerebrospinal fluid (CSF) drainage, 81-times more than controls (P < 0.0001). CSF drainage reduced mortality by 44% among DWS patients (P < 0.0001). Although DWS is associated with a 10-fold increase in mortality, operative CSF drainage nearly halves the mortality rate. Based on these findings (Class IIB evidence), it is likely that the increased mortality associated with DWS is directly attributable to the nearly 80% of DWS patients who did not receive operative CSF drainage for hydrocephalus. Consequently, increased access to neurosurgical intervention could reduce the mortality rate of DWS towards that of the general population. PMID:25552847

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

2015-01-01

370

A Deletion in the VLDLR Gene in Eurasier Dogs with Cerebellar Hypoplasia Resembling a Dandy-Walker-Like Malformation (DWLM).  

PubMed

Dandy-Walker-like malformation (DWLM) is the result of aberrant brain development and mainly characterized by cerebellar hypoplasia. DWLM affected dogs display a non-progressive cerebellar ataxia. Several DWLM cases were recently observed in the Eurasier dog breed, which strongly suggested a monogenic autosomal recessive inheritance in this breed. We performed a genome-wide association study (GWAS) with 9 cases and 11 controls and found the best association of DWLM with markers on chromosome 1. Subsequent homozygosity mapping confirmed that all 9 cases were homozygous for a shared haplotype in this region, which delineated a critical interval of 3.35 Mb. We sequenced the genome of an affected Eurasier and compared it with the Boxer reference genome and 47 control genomes of dogs from other breeds. This analysis revealed 4 private non-synonymous variants in the critical interval of the affected Eurasier. We genotyped these variants in additional dogs and found perfect association for only one of these variants, a single base deletion in the VLDLR gene encoding the very low density lipoprotein receptor. This variant, VLDLR:c.1713delC is predicted to cause a frameshift and premature stop codon (p.W572Gfs*10). Variants in the VLDLR gene have been shown to cause congenital cerebellar ataxia and mental retardation in human patients and Vldlr knockout mice also display an ataxia phenotype. Our combined genetic data together with the functional knowledge on the VLDLR gene from other species thus strongly suggest that VLDLR:c.1713delC is indeed causing DWLM in Eurasier dogs. PMID:25668033

Gerber, Martina; Fischer, Andrea; Jagannathan, Vidhya; Drögemüller, Michaela; Drögemüller, Cord; Schmidt, Martin J; Bernardino, Filipa; Manz, Eberhard; Matiasek, Kaspar; Rentmeister, Kai; Leeb, Tosso

2015-01-01

371

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

372

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

USGS Publications Warehouse

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

Williams, A. Park; Funk, Chris

2011-01-01

373

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

PubMed Central

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

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

2014-01-01

374

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

375

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

NASA Astrophysics Data System (ADS)

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

Umhoefer, P. J.

2012-12-01

376

Natural products-based insecticidal agents 5. Design, semisynthesis and insecticidal activity of novel 4'-substituted benzenesulfonate derivatives of 4-deoxypodophyllotoxin against Mythimna separata Walker in vivo.  

PubMed

In an attempt to find the effective phytopesticides, eight novel 4'-substituted benzenesulfonate derivatives of 4-deoxypodophyllotoxin were synthesized and preliminarily tested against the pre-third-instar larvae of Mythimna separata Walker in vivo at the concentration of 1mg/mL. Among all of the tested analogs, compounds 5a, 5c, 5d, and 5h showed the higher insecticidal activity than 4-deoxypodophyllotoxin. Especially 5a exhibited the most potent insecticidal activity compared with toosendanin, a commercial insecticide derived from Melia azedarach. PMID:20346661

Xu, Hui; Wang, Juan-Juan

2010-04-15

377

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

SciTech Connect

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

Lutz, Brian D [Duke University; Mulholland, Patrick J [ORNL; Bernhardt, Emily [Duke University

2012-01-01

378

Interview with John Walker  

E-print Network

and collecting their tears to get lysozyme for the antibacterial properties; Edward Abraham joined them and was part of the penicillin team; his work was mainly on determining the chemical structure of penicillin during the War for which Chain, Florey and Fleming... were given the Nobel Prize; detected some resentment on Abraham's part over this; penicillin consists of two fused ring structures one of them called beta-lactam ring which Abraham's proposed and all the other chemists, including Robinson and Cornforth...

Walker, John E

2008-08-13

379

Artificial Tribotactic Microscopic Walkers  

E-print Network

Friction, the resistive force between two surfaces sliding past each other, is at the core of a wide diversity of locomotion schemes. While such schemes are somewhat understood for homogeneous environments, locomotion based on friction in inhomogeneous environments has not received much attention. Here, we introduce and demonstrate the concept of tribotaxis by utilizing microwalkers that detect gradients in the friction coefficient controlled by the density of biological receptors on the substrate. When actuated stochastically, these microwalkers migrate to regions of higher friction, effectively performing chemotaxis. Simulations and theory based on biased random walks are in excellent agreement with experiments. Our results may have important implications in artificial and natural locomotion in biological environments because interfaces are a prominent motif in nature.

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

2014-03-10

380

1 Mark E. Walker  

E-print Network

Geometry", (I was * *one of six faculty on this grant), June 1997 - May 2000; $30,030. 3.NSA faculty on this grant), July 2000 - June 2004; $45,936. 5.NSA Grant, "Semi-topological K for this grant, not I. 7.NSA Grant, "K-theory, Lawson Homology, and Hodge Theory", January 2005 - D

Walker, Mark

381

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

PubMed Central

Transmembrane channel proteins play pivotal roles in maintaining the homeostasis and responsiveness of cells and the cross-membrane electrochemical gradient by mediating the transport of ions and molecules through biological membranes. Therefore, computational methods which, given a set of 3D coordinates, can automatically identify and describe channels in transmembrane proteins are key tools to provide insights into how they function. Herein we present PoreWalker, a fully automated method, which detects and fully characterises channels in transmembrane proteins from their 3D structures. A stepwise procedure is followed in which the pore centre and pore axis are first identified and optimised using geometric criteria, and then the biggest and longest cavity through the channel is detected. Finally, pore features, including diameter profiles, pore-lining residues, size, shape and regularity of the pore are calculated, providing a quantitative and visual characterization of the channel. To illustrate the use of this tool, the method was applied to several structures of transmembrane channel proteins and was able to identify shape/size/residue features representative of specific channel families. The software is available as a web-based resource at http://www.ebi.ac.uk/thornton-srv/software/PoreWalker/. PMID:19609355

Thornton, Janet M.

2009-01-01

382

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

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

383

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

384

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

385

Paleomagnetic Evaluation of Crustal-Scale Block Rotations in the Mina Deflection of the Central Walker Lane  

NASA Astrophysics Data System (ADS)

Crustal deformation resulting from relative Pacific-North America plate motion is broadly distributed on faults across the western U.S.. Geodetic observations show that some 25 percent of transform plate motion is currently accommodated by faults east of the Sierra Nevada, from the eastern California shear zone to the central Walker Lane (CWL). The northwest trending faults of the CWL are joined to the Furnace Creek - Owens Valley fault system by the Mina deflection, a belt of east-northeast striking faults that serve as a displacement transfer system linking the two fault zones. The Furnace Creek - Owens Valley fault system has a cumulative right-slip of 40 - 50 km, and this displacement is transferred in an extensional right-step to the curved high-angle faults of the Mina deflection. The high-angle fault geometry and basin depths preclude more than 10 km of right-lateral displacement accommodated along structures in the Mina deflection and thus a slip deficit of 30 to 40 km exists. We are attempting to resolve the amount of permanent Neogene strain in the Mina deflection and determine if the geodetically observed strain accumulation and local heterogeneities are consistent with the permanent Neogene strain, in particular, vertical axis rotation of blocks in the Mina deflection area. To in part quantify the magnitude and potential heterogeneities of crustal block rotation and to more clearly define block boundaries, paleomagnetic data have been obtained from numerous stratigraphic sections of upper Tertiary volcanic rocks in a 300 sqkm area centered on the Candeleria Hills, NV. Eight to ten oriented samples from 260 sites distributed across multiple tectonic blocks have been fully demagnetized with all sites yielding interpretable results (23 sites (two sections) in mid Miocene andesite flows, 102 sites (10 sections) in upper Miocene basalt flows, and 135 sites (27 sections) in lower Miocene, regionally extensive ash flow tuffs). Although some anomalous directions were observed, the stratigraphically corrected (typically less than 15° dip) data from the volcanic rocks are internally consistent, well-grouped at the site level, and discordant clockwise to late Cenozoic expected field direction (358\\deg, 58\\deg). For example, a Miocene basalt flow section in the central Candelaria Hills yields a group mean (D = 16.5, I = 50.0, a95 = 1.8, k = 497.3) that provides an inferred rotation of +18.5\\deg +/- 6.9\\deg compared to a late Cenozoic expected field. Two sites in the Candelaria Junction regional ash flow tuff located in separate structural blocks yield similar inclinations, yet statistically distinct declinations (Site1, 255.8, -48.6, 4.4; Site2, 296.4, -41.0, 4.6), providing evidence for a modest clockwise vertical axis rotation between structural blocks. Overall, we interpret most data obtained to reflect at most moderate clockwise vertical axis rotation among structural blocks in the Mina deflection region. The absence of large magnitude rotation of any individual block and, thus between blocks, places limits on the amount of cumulative slip on fault networks in the Mina deflection. The area may be accommodating strain by net northwest extension on a curved fault array with very low rates of vertical axis rotation and minor slip on individual faults. To compare the geodetic observations with long-term strain, we are developing a tectonic model, using existing fault geometries and paleomagnetic data for the CWL that links vertical axis rotations of the fragmented upper crust to the driving mechanisms associated with slip transfer across the region.

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

2004-12-01

386

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

SciTech Connect

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

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

2009-03-15

387

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

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

388

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

389

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

PubMed Central

Background Patients with hand and/or wrist pathology are recommended to have a four-wheeled walker with an arm rest (FWW-AR) rather than a standard walker or a standard four-wheeled walker (FWW). However, only a few quantitative studies have been performed to compare upper and lower extremity weight bearing. The aim of this study was to evaluate forearm and foot weight bearing using a FWW-AR and the effect of the armrest height. Methods Eleven elderly women (mean age 80.1±5.3 years; mean height 148.5±4.0 cm; mean weight 51.2±9.0 kg) were enrolled. The subjects walked with an FWW-AR, with the elbow in either 90 degree (D90) or 130 degree (D130) flexion, for a distance of 10 m. Surface electromyographic signals were recorded for the upper, middle, and lower trapezius, anterior deltoid, and erector spinae muscles; walking velocity was measured with the subjects weight bearing on their feet and forearms while walking. Simultaneously, the maximum plantar and forearm loads during walking with an FWW-AR were measured. Results The normalized foot plantar loads were lower at D90 than at D130, while the normalized forearm load was higher at D90 than at D130 (all P<0.05; left foot, 7.9±0.1 N/kg versus 8.8±0.1 N/kg; right foot, 8.6±0.2 N/kg versus. 9.6±0.1 N/kg; left forearm, 1.8±0.5 N/kg versus 0.8±0.2 N/kg; and right forearm, 2.0±0.5 N/kg versus 1.0±0.2 N/kg, respectively). The surface electromyographic activity of the muscles involved in shoulder elevation and the walking velocity were both lower with the elbow at D90 than at D130 (all P<0.05; left upper trapezius, 98.7%±19.5% versus 132.6%±16.9%; right upper trapezius, 83.4%±10.6% versus 108.1%±10.5%; left anterior deltoid, 94.1%±12.8% versus 158.6%±40.4%; right anterior deltoid, 99.1%±15.0% versus 151.9%±19.4%; and velocity, 0.6±0.1 m/sec versus 0.7±0.1 m/sec, respectively). Conclusion Weight bearing on the lower extremities is significantly reduced when the upper extremities are supported during walking with an FWW-AR. Furthermore, the weight bearing profile is dependent on the armrest height. PMID:25342894

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

2014-01-01

390

Kinematics of Deformation in West-Central Walker Lane; Paleomagnetic Testing of Fault-Block Rotation and Doming Models, Eastern California and Western Nevada  

NASA Astrophysics Data System (ADS)

Walker Lane is a broad (~100-200 km) zone of dextral shear located between the Sierra Nevada microplate and the Basin and Range Province. We consider Bodie Hills a part of the greater Walker Lane because it has experienced clockwise, vertical-axis rotation of crustal blocks due to dextral shear accommodation. This strain is variable, resulting in rotations ranging from ~10°-70° depending on location. The Miocene Eureka Valley Tuff (EVT) is an ideal strain marker, because it is a geologically instantaneous and laterally extensive unit. We use paleomagnetic analysis of ignimbrites to improve the resolution of strain domain boundaries as well as test for doming in Bodie Hills. EVT site mean directions were compared to reference directions of the Tollhouse Flat and By Day Members collected from the stable Sierra Nevada to determine magnitudes of vertical-axis rotation. Three new sites and three previously sampled sites define a high-rotation domain including Bridgeport Valley and the East Walker River Canyon with an average clockwise rotation of ~50°-60°. We define the eastern boundary of this high-rotation domain as coinciding with a mapped fault exhibiting 11.7°×7.9° rotation of the presumed footwall. Our data corroborates and improves on Carlson's (2012) kinematic model in which the greater Bodie Hills has rotated clockwise ~30° since EVT emplacement. Eutaxitic textures, dipping up to 90°, are gross indicators of true tilt, but are also influenced by original dips in some localities, complicating interpretations. John et al. (2012) describe a simple doming model of Bodie Hills since EVT emplacement, supported by the high elevation of outflow channels compared to source areas. Our paleomagnetic data does not support simple doming, suggesting that there is either no doming of Bodie Hills, or that vertical crustal displacements have occurred without large-scale folding. John et al. (2012) dated undifferentiated EVT in Bodie Hills at ~9.4 Ma; using paleomagnetism, we show the dated outcrops to be Tollhouse Flat Member, substantially improving age constraints on EVT.

Fredrickson, S. M.; Pluhar, C. J.; Carlson, C. W.

2013-12-01

391

Assessment of Prey Preference by the Generalist Predator, Mallada basalis (Walker), When Offered Two Species of Spider Mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor) on Papaya  

Technology Transfer Automated Retrieval System (TEKTRAN)

We investigated potential prey preference of the generalist predator Mallada basalis (Walker) when offered two mites, Tetranychus kanzawai Kishida and Panonychus citri (McGregor), both important pests on papaya. Laboratory choice tests revealed that none of the three larval instars of M. basalis sho...

392

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

PubMed Central

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

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

2014-01-01

393

Walker Gilmore: a stratified Woodland period occupation in eastern Nebraska. A report of the 1968 excavations. Final report 1968-83  

SciTech Connect

Excavations at Walker Gilmore were designed to test the ill-defined concept of 'Sterns Creek culture' in the Central Plains subarea. Five Woodland period levels produced evidence for 48 tool classes, flora and fauna, and 762 features including structural remains. Level 1 is poorly recorded and relatively unknown. Levels 2 - 4 contain abundant evidence of subsistence, structure, and settlement. Broad spectrum hunting/gathering and horticulture are represented. Site structures includes food preparation areas associated with storage/drying facilities, hearths, and trash pits. Settlements appear to be semi-permanent, and involved in diverse procurement activities spanning two or more seasons. Level 2 habitation is radiocarbon dated between A.D. 1116 to 1255, which indicates contemporary development with Central Plains Tradition complexes, as well as Loseke Creek/Missouri Bluffs Woodland groups. Level 5 evidences settlement change as probable interaction with Central Plains Tradition complexes.

Haas, D.R.

1983-12-01

394

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

PubMed Central

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

2013-01-01

395

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

PubMed

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

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

2013-10-15

396

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

397

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

NASA Astrophysics Data System (ADS)

The Sierra Nevada - Great Valley (SNGV) micro-plate has long been recognized as a tectonically rigid, though mobile, entity within the Pacific - North America plate boundary zone. The motion of the SNGV relative to stable North America (and the Colorado Plateau) provides the kinematic boundary condition for, and perhaps drives, the deformation in the Basin and Range Province (BRP) and Walker Lane. In the north the motion of the SNGV is aligned with the Mohawk Valley fault zone, which could have a slip rate of over a few mm/yr. The crest of the Sierras marks the SNGV’s eastern edge, but the obliquity between orientation of this boundary and the block’s motion implies an expected increase in rangefront-normal extension from the northern to southern Walker Lane. We use new GPS data from the EarthScope Plate Boundary Observatory (PBO) and our own semi-continuous MAGNET network to revisit the following questions: 1) Do the data still support rigidity of the SNGV?; 2) How far east does the rigidity extend and how does this relate to SNGV lithology?; 3) How does the direction of SNGV motion relate to the strike of its eastern margin and observed strain partitioning (and its along strike variation) in the Walker Lane?; and 4) How is SNGV-BRP motion accommodated between the Walker Lane and the Cascadia forearc? We analyze data from all the available continuous GPS sites in the greater SNGV region, including new data from PBO, as well as data from MAGNET. All data are processed with the GIPSY-OASIS II precise point positioning software using recently reprocessed orbits from JPL's IGS Analysis Center. The processing includes satellite and station antenna calibrations and all data have the phase ambiguities fixed using the Ambizap algorithm. Positions are estimated in our custom-made North America reference frame in which continental-scale common-mode errors are removed. Velocities and uncertainties are estimated using the CATS software in which we assuming an error model with flicker plus white noise. Many stations in the Great Valley show anomalous horizontal motions compared to the most stable stations in the Sierra Nevada Mountains. These motions are likely due to hydrological effects in the Great Valley, which can be seen in the significant subsidence that occurs at these stations. Consequently, there are a relatively small number of stations that should be used to constrain the SNGV rigid body rotation. We find that stations in the southernmost Sierra Nevada Mountains have a northward motion of >1 mm/yr relative to the central and northern Sierras. This could partly be explained in terms of regional post-seismic viscoelastic relaxation from recent earthquakes (e.g. Kern County 1952, Landers, 1992, Hector Mine1999), but may also reflect the region’s anomalous mantle dynamics.

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

2009-12-01

398

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

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

399

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

400

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

SciTech Connect

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

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

2012-06-01

401

Crustal Deformation across the Sierra Nevada-Northern Walker Lane, Basin and Range Transition, Western United States Measured with GPS, 2000-2004  

NASA Astrophysics Data System (ADS)

In the northern Walker Lane (WL) of northwest Nevada and northeast California, approximately 20-25% of the contemporary Pacific/North America relative plate motion is accommodated east of the Sierra Nevada in a focused zone of dextral shear and extension. Previous measurements with the Global Positioning System (GPS) have identified a partitioning of shear and extension and a widening of the zone of active deformation north of 39? north latitude. This deformation pattern may indicate that northwest-directed extension in the Basin and Range east of the WL becomes more active northward, making up for a northward decrease in northwest-directed dextral slip on the WL strike slip faults. Alternatively (or additionally), it may be an effect of postseismic relaxation following the 20th century earthquakes in the Central Nevada Seismic Belt (CNSB), east of the WL. We present velocities and strain rate tensors obtained from newly collected GPS data along networks that extend from the Central Great Valley of California, across the Sierra Nevada, Walker Lane and into the central Basin and Range province. Campaign surveys in September 2000 and September 2004 occupied 56 sites that have greater spatial density (<20 km), and lie outside the footprint of the planned deployment of the Plate Boundary Observatory Extension/Backbone continuous GPS cluster. These networks fill gaps in previous GPS coverage, and between the sparsely (near 100 km) spaced continuously recording Basin and Range Geodetic Network (BARGEN), whose data we include in our GIPSY/OASIS II processing. Additionally, our solution will include GPS data from 40+ stations of a new network of semi-continuous sites: the Nevada Mobile Array of GPS for Nevada Transtension (MAGNET), which commenced operation the end of January 2004 and currently has <1 year of data, but provides a complementary spatial distribution of sites and will, in future, greatly enhance constraint on WLB surface deformation. We will use the combined solution to provide new constraints on postseismic relaxation on the CNSB and on plate boundary kinematics in the northern WL.

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

2004-12-01

402

Relationships between structure and molting hormonal activity of tebufenozide, methoxyfenozide, and their analogs in cultured integument system of Chilo suppressalis Walker.  

PubMed

The molting hormonal activity of methoxyfenozide (RH-2485), tebufenozide (RH-5992), five analogs with various alkyl groups, and 18 acyl analogs was measured by using cultured integument of rice stem borers, Chilo suppressalis Walker. The hormonal activity of methoxyfenozide was remarkably high (EC(50) = 1.1 x 10(-9) M), being equivalent to that of tebufenozide (RH-5992). The hormonal activity of several tebufenozide analogs with varying alkyl groups such as CH(3), n-C(3)H(7), i-C(3)H(7), n-C(4)H(9) and n-C(5)H(11) at the para-position of the benzene ring furthest from the tert-butyl group was lower than that of tebufenozide (alkyl group is C(2)H(5)). The activity decreased to varying degrees as a result of replacement of the 3,5-dimethylphenyl moiety of tebufenozide with either a phenyl, naphthyl, or cyclohexyl group. Both 1- and 2-naphthyl derivatives were very active (EC(50) = 4.3 x 10(-8) M and 3.2 x 10(-8) M, respectively) without any significant difference between them. The activity of the 1-cyclohexenyl analog (EC(50) = 1.0 x 10(-7) M) was about 40x that of the corresponding 3-cyclohexenyl analog (EC(50) = 4.4 x 10(-6) M), but 1/100 that of tebufenozide. The activity varied parabolically with respect to the molecular hydrophobicity, and decreased with longer acyl moieties. PMID:10699589

Nakagawa, Y; Hattori, K; Minakuchi, C; Kugimiya, S; Ueno, T

2000-03-01

403

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

PubMed Central

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

2013-01-01

404

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

PubMed

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

Tomasin, Rebeka; Gomes-Marcondes, Maria Cristina Cintra

2011-04-01

405

FOXC1 is required for normal cerebellar development and is a major contributor to chromosome 6p25.3 Dandy-Walker malformation  

PubMed Central

Dandy-Walker malformation (DWM), the most common human cerebellar malformation, has only one characterized associated locus1,2. Here we characterize a second DWM-linked locus on 6p25.3, showing that deletions or duplications encompassing FOXC1 are associated with cerebellar and posterior fossa malformations including cerebellar vermis hypoplasia (CVH), mega-cisterna magna (MCM) and DWM. Foxc1-null mice have embryonic abnormalities of the rhombic lip due to loss of mesenchyme-secreted signaling molecules with subsequent loss of Atoh1 expression in vermis. Foxc1 homozygous hypomorphs have CVH with medial fusion and foliation defects. Human FOXC1 heterozygous mutations are known to affect eye development, causing a spectrum of glaucoma-associated anomalies (Axenfeld-Rieger syndrome, ARS; MIM no. 601631). We report the first brain imaging data from humans with FOXC1 mutations and show that these individuals also have CVH. We conclude that alteration of FOXC1 function alone causes CVH and contributes to MCM and DWM. Our results highlight a previously unrecognized role for mesenchyme-neuroepithelium interactions in the mid-hindbrain during early embryogenesis. PMID:19668217

Aldinger, Kimberly A; Lehmann, Ordan J; Hudgins, Louanne; Chizhikov, Victor V; Bassuk, Alexander G; Ades, Lesley C; Krantz, Ian D; Dobyns, William B; Millen, Kathleen J

2010-01-01

406

FOXC1 is required for normal cerebellar development and is a major contributor to chromosome 6p25.3 Dandy-Walker malformation.  

PubMed

Dandy-Walker malformation (DWM), the most common human cerebellar malformation, has only one characterized associated locus. Here we characterize a second DWM-linked locus on 6p25.3, showing that deletions or duplications encompassing FOXC1 are associated with cerebellar and posterior fossa malformations including cerebellar vermis hypoplasia (CVH), mega-cisterna magna (MCM) and DWM. Foxc1-null mice have embryonic abnormalities of the rhombic lip due to loss of mesenchyme-secreted signaling molecules with subsequent loss of Atoh1 expression in vermis. Foxc1 homozygous hypomorphs have CVH with medial fusion and foliation defects. Human FOXC1 heterozygous mutations are known to affect eye development, causing a spectrum of glaucoma-associated anomalies (Axenfeld-Rieger syndrome, ARS; MIM no. 601631). We report the first brain imaging data from humans with FOXC1 mutations and show that these individuals also have CVH. We conclude that alteration of FOXC1 function alone causes CVH and contributes to MCM and DWM. Our results highlight a previously unrecognized role for mesenchyme-neuroepithelium interactions in the mid-hindbrain during early embryogenesis. PMID:19668217

Aldinger, Kimberly A; Lehmann, Ordan J; Hudgins, Louanne; Chizhikov, Victor V; Bassuk, Alexander G; Ades, Lesley C; Krantz, Ian D; Dobyns, William B; Millen, Kathleen J

2009-09-01

407

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

PubMed Central

Background Patients with advanced cancer suffer from cachexia, which is characterised by a marked weight loss, and is invariably associated with the presence of tumoral and humoral factors which are mainly responsible for the depletion of fat stores and muscular tissue. Methods In this work, we used cytotoxicity and enzymatic assays and morphological analysis to examine the effects of a proteolysis-inducing factor (PIF)-like molecule purified from ascitic fluid of Walker tumour-bearing rats (WF), which has been suggested to be responsible for muscle atrophy, on cultured C2C12 muscle cells. Results WF decreased the viability of C2C12 myotubes, especially at concentrations of 20–25 ?g.mL-1. There was an increase in the content of the pro-oxidant malondialdehyde, and a decrease in antioxidant enzyme activity. Myotubes protein synthesis decreased and protein degradation increased together with an enhanced in the chymotrypsin-like enzyme activity, a measure of functional proteasome activity, after treatment with WF. Morphological alterations such as cell retraction and the presence of numerous cells in suspension were observed, particularly at high WF concentrations. Conclusion These results indicate that WF has similar effects to those of proteolysis-inducing factor, but is less potent than the latter. Further studies are required to determine the precise role of WF in this experimental model. PMID:18226207

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

2008-01-01

408

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

PubMed

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

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

2009-03-01

409

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

PubMed Central

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

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

2015-01-01

410

Transgenic loblolly pine (Pinus taeda L.) plants expressing a modified delta-endotoxin gene of Bacillus thuringiensis with enhanced resistance to Dendrolimus punctatus Walker and Crypyothelea formosicola Staud.  

PubMed

A synthetic version of the CRY1Ac gene of Bacillus thuringiensis has been used for the transformation of loblolly pine (Pinus taeda L.) using particle bombardment. Mature zygotic embryos were used to be bombarded and to generate organogenic callus and transgenic regenerated plants. Expression vector pB48.215 DNA contained a synthetic Bacillus thuringiensis (B.t.) CRY1Ac coding sequence flanked by the double cauliflower mosaic virus (CaMV) 35S promoter and nopaline synthase (NOS) terminator sequences, and the neomycin phosphotransferase II (NPTII) gene controlled by the promoter of the nopaline synthase gene was introduced into loblolly pine tissues by particle bombardment. The transformed tissues were proliferated and selected on media with kanamycin. Shoot regeneration was induced from the kanamycin-resistant calli, and transgenic plantlets were then produced. More than 60 transformed plants from independent transformation events were obtained for each loblolly pine genotype tested. The integration and expression of the introduced genes in the transgenic loblolly pine plants was confirmed by polymerase chain reactions (PCR) analysis, by Southern hybridization, by Northern blot analysis, and by Western blot analysis. Effective resistance of transgenic plants against Dendrolimus punctatus Walker and Crypyothelea formosicola Staud was verified in feeding bioassays with the insects. The transgenic plants recovered could represent a good opportunity to analyse the impact of genetic engineering of pine for sustainable resistance to pests using a B. thuringiensis insecticidal protein. This protocol enabled the routine transformation of loblolly pine plants that were previously difficult to transform. PMID:12554726

Tang, Wei; Tian, Yingchuan

2003-02-01

411

Kinematic Implications of New Paleomagnetic Data From the Northern Walker Lane, Western Nevada: Counterintuitive Anticlockwise Vertical-Axis Rotation in an Incipient Dextral Shear Zone  

NASA Astrophysics Data System (ADS)

The Walker Lane/eastern California shear zone is a major dextral fault system that splays from the San Andreas fault in southern California and shunts 20-25% of the Pacific-North America transform motion east of the Sierra Nevada block. In NW Nevada and NE California, the north end of the system has developed in the past 3-6 Ma and is propagating northwestward in the wake of the retreating Cascade arc. This rapidly evolving region, known as the northern Walker Lane (NWL), is one of the youngest parts of the Pacific-North America transform margin and therefore affords an opportunity to analyze the incipient development of a major strike-slip fault system. The NWL consists of kinematically linked NW-striking, left-stepping right-lateral faults, N-striking normal faults, and subordinate ENE-striking sinistral faults. Major dextral faults terminate in arrays of northerly striking normal faults in the western Great Basin. The en echelon left-stepping pattern of dextral faults is a curious geometry. Although small left steps on individual faults are associated with local shortening, the broad left steps between major dextral faults accommodate little, if any, shortening and are therefore unlike typical restraining bends. One possible model is that the left-stepping dextral faults are primary Riedel shears developing above a dextral shear zone at depth. The ENE-striking sinistral faults may be secondary, conjugate Riedel shears. Paleomagnetic data from the 25.1 Ma Nine Hill Tuff indicate slight anticlockwise rotation of blocks between the overlapping, NW-striking dextral faults. Our work has established a new reference direction (D=341, I=55, a95=4, 11 sites; 83 samples) for Nine Hill Tuff in the presumably unrotated Sierra Nevada. Data from the Nine Hill Tuff in the NWL suggest about 15 deg of anticlockwise rotation of the Virginia Mts, Dogskin Mt, and Seven Lakes Mt (D=326, I=52, a95=7, 12 sites) but negligible rotation of the Fort Sage Mts (D=342, I=55, a95=13, 5 sites). Slight anticlockwise rotation is also supported by paleomagnetic data from the 28.6 Ma tuff of Campbell Creek (D=191, I= -40 [2 sites] compared to reference direction of D=205, I= -43, a95=3 [10 sites in Sierra Nevada]) and the predominance of WNW-striking strata in these fault blocks, which contrasts with a more northerly striking regional norm. However, data from the Nine Hill Tuff do indicate 30-60 deg of clockwise rotation (D=16, I=47, a95=10, 6 sites) in narrow 2 km wide bands along major dextral faults in the NWL. In the transtensional setting of the NWL, the slight anticlockwise rotation may reflect coeval E-W to WNW regional extension and NW-directed dextral shear. In this model, extension induces a domino-like, map-view collapse and slight anticlockwise rotation of fault blocks between the left-stepping dextral faults. The anticlockwise rotation is opposite to the clockwise rotation typically found in dextral shear zones. Anticlockwise rotation may ultimately rotate Riedel shears toward the main shear zone at depth, thus facilitating eventual development of a through-going, upper-crustal strike-slip fault. Ironically, as the system matures and a through-going fault develops, the predominant sense of vertical-axis rotation may reverse and become compatible with the dextral sense of shear. Such complex kinematics may characterize incipient strike-slip fault systems in both transtensional and transpressional settings.

Faulds, J. E.; Henry, C. D.; Hinz, N. H.; Delwiche, B.; Cashman, P. H.

2004-12-01

412

Transcriptomics and Identification of the Chemoreceptor Superfamily of the Pupal Parasitoid of the Oriental Fruit Fly, Spalangia endius Walker (Hymenoptera: Pteromalidae)  

PubMed Central

Background The oriental fruit fly, Bactrocera dorsalis Hendel, causes serious losses to fruit production and is one of the most economically important pests in many countries, including China, Spalangia endius Walker is a pupal parasitoid of various dipteran hosts, and may be considered a potentially important ectoparasitic pupal parasitoid of B. dorsalis. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its interaction with this host. Analysis of the S. endius transcriptome is essential to extend the resources of genetic information on this species and, to support studies on S. endius on the host B. dorsalis. Methodology/Principal Findings We performed de novo assembly RNA-seq of S. endius. We obtained nearly 10 Gbp of data using a HiSeq platform, and 36319 high-quality transcripts using Trinity software. A total of 22443 (61.79%) unigenes were aligned to homologous sequences in the jewel wasp and honeybee (Apis florae) protein set from public databases. A total of 10037 protein domains were identified in 7892 S. endius transcripts using HMMER3 software. We identified expression of six gustatory receptor and 21 odorant receptor genes in the sample, with only one gene having a high expression level in each family. The other genes had a low expression level, including two genes regulated by splicing. This result may be due to the wasps being kept under laboratory conditions. Additionally, a total of 3727 SSR markers were predicted, which could facilitate the identification of polymorphisms and functional genes within wasp populations. Conclusion/Significance This transcriptome greatly improves our genetic understanding of S. endius and provides a large number of gene sequences for further study. PMID:24505315

Zhang, Yuping; Zheng, Yuan; Li, Dunsong; Fan, Yilin

2014-01-01

413

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

PubMed Central

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

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

2013-01-01

414

Impulse Action on D-particles in Robertson-Walker Space Times, Higher-Order Logarithmic Conformal Algebras and Cosmological Horizons  

E-print Network

We demonstrate that an impulse action (`recoil') on a D-particle embedded in a (four-dimensional) cosmological Robertson-Walker (RW) spacetime is described, in a $\\sigma$-model framework, by a suitably extended higher-order logarithmic world-sheet algebra of relevant deformations. We study in some detail the algebra of the appropriate two-point correlators, and give a careful discussion as to how one can approach the world-sheet renormalization group infrared fixed point, in the neighborhood of which the logarithmic algebra is valid. It is found that, if the initial RW spacetime does not have cosmological horizons, then there is no problem in approaching the fixed point. However, in the presence of horizons, there are world-sheet divergences which imply the need for Liouville dressing in order to approach the fixed point in the correct way. A detailed analysis on the subtle subtraction of these divergences in the latter case is given. In both cases, at the fixed point, the recoil-induced spacetime is nothing other than a coordinate transformation of the initial spacetime into the rest frame of the recoiling D-particle. However, in the horizon case, if one identifies the Liouville mode with the target time, which expresses physically the back reaction of the recoiling D-particle onto the spacetime structure, it is found that the induced spacetime distortion results in the removal of the initial cosmological horizon and the eventual stopping of the acceleration of the Universe. In this latter sense, our model may be thought of as a conformal field theory description of a (toy) Universe characterized by a sort of `phase transition' at the moment of impulse, implying a time-varying speed of light.

Elias Gravanis; Nick E. Mavromatos

2001-06-16

415

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

PubMed

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

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

2013-01-01

416

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

PubMed

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

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

2014-03-01

417

Modeling transcription factor binding events to DNA using a random walker/jumper representation on a 1D/2D lattice with different affinity sites  

NASA Astrophysics Data System (ADS)

Surviving in a diverse environment requires corresponding organism responses. At the cellular level, such adjustment relies on the transcription factors (TFs) which must rapidly find their target sequences amidst a vast amount of non-relevant sequences on DNA molecules. Whether these transcription factors locate their target sites through a 1D or 3D pathway is still a matter of speculation. It has been suggested that the optimum search time is when the protein equally shares its search time between 1D and 3D diffusions. In this paper, we study the above problem using Monte Carlo simulations by considering a simple physical model. A 1D strip, representing a DNA, with a number of low affinity sites, corresponding to non-target sites, and high affinity sites, corresponding to target sites, is considered and later extended to a 2D strip. We study the 1D and 3D exploration pathways, and combinations thereof by considering three different types of molecules: a walker that randomly walks along the strip with no dissociation; a jumper that represents dissociation and then re-association of a TF with the strip at later time at a distant site; and a hopper that is similar to the jumper but it dissociates and then re-associates at a faster rate than the jumper. We analyze the final probability distribution of molecules for each case and find that TFs can locate their targets on the experimental time scale even if they spend only 15% of their search time diffusing freely in the solution. This agrees with recent experimental results obtained by Elf et al (2007 Science 316 1191) and is in contrast to previously reported theoretical predictions. Our results also agree with the experimental evidence for the role of chaperons and proteasomes in stabilizing and destabilizing TFs binding, respectively, during the regulation process. Therefore, the results of our manuscript can provide a refined theoretical framework for the process.

Rezania, Vahid; Tuszynski, Jack; Hendzel, Michael

2007-12-01

418

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

NASA Astrophysics Data System (ADS)

The Walker Lane Belt (WLB) transfer zone, which initiated in the mid-Miocene, presently links the Eastern California Shear Zone (ECSZ) in the south to the Central Nevada Seismic Belt (CNSB) and WLB to the east and north, respectively. This transfer zone is part of a diffuse intracontinental deformation zone that accommodates some 25 percent of the current motion between the North American and Pacific plates. The boundary of the transfer system is clear on the northern and western margins but the extent of the system to the south and east is only inferred. The extent of deformation and development of the WLB transfer zone since the mid-Miocene is being examined by a paleomagnetic study of 125 sites that includes Miocene to mid-Pliocene volcanic and shallow intrusive rocks near the inferred southern and eastern boundaries. Results from 39 sites inside and along the southern boundary (i.e. Goldfield Hills, Montezuma Range, Clayton Ridge) show about 30° of clockwise rotation (D = 028.3°, I = 57.8°, ?95 = 3.9°, discordant from the expected Neogene direction of D = 358°, I = 55°). The area where 13 of these 39 sites are located (i.e. northern Amargosa Range, eastern Slate Ridge) was previously thought to lie outside of the inferred boundary, yet it also shows about 30° of clockwise rotation (D = 031.2°, I = 52.4°, ?95 = 6.7°). Areas along the eastern boundary (i.e. southern San Antonio Range) of the transfer zone are still under investigation; data obtained to date are not internally consistent. Overall, the available paleomagnetic data suggest that the southern extent of the WLB transfer zone was larger than previously expected during the mid-Miocene to mid-Pliocene, and based on previous paleomagnetic, structural, and geodetic studies of the area, support a transition from more diffuse to localized deformation (forming the Mina Deflection) at about 3 Ma.

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

2008-12-01

419

Covariance of structural and stratigraphic trends: Evidence for anticlockwise rotation within the Walker Lane belt Death Valley region, California and Nevada  

NASA Astrophysics Data System (ADS)

Large-magnitude relative rotations of range-scale structural blocks are inferred to be products of crustal extension in the Death Valley region, in California and Nevada. Reconstructions of the extended terrain restore pre-Tertiary contractile structures with currently diverse trends into a relatively simple, north-northeast trending thrust belt. We interpret trends of major contractile structures throughout the Death Valley region as characteristically discordant to, and thus geometrically independent from, stratigraphic trends. We compare trends of pre-Tertiary contractile structures with paleoflow orientations in Lower Cambrian strata throughout the extended terrain. Significant differences between mean paleoflow orientations are consistent in magnitude and sense with differences observed in the structural trends. Available evidence does not support interpretation of paleoflow data from apparently rotated areas as representing an original paleogeography distinct from that of adjacent areas. Facies variations are present within the contractile structures. We interpret the strong covariance throughout the study area between structural and paleoflow trends of diverse orientations as evidence for vertical axis rotations. Combined rotation estimates from these data indicate clockwise rotations of 85° ± 12° for Bare Mountain and 73° ± 24° for the Striped Hills but anticlockwise rotations of 30° ± 35° and 87° ± 29°, respectively, for the northern and southern Grapevine Mountains. Such large rotations of opposite sense may be related to north-south shortening accommodated by conjugate strike-slip faults during large-magnitude extension in the Death Valley region but are difficult to explain as products of regional dextral shear within the southern Walker Lane belt.

Snow, J. Kent; Prave, Anthony R.

1994-06-01

420

A 2.84 Mb deletion at 21q22.11 in a patient clinically diagnosed with Marden-Walker syndrome.  

PubMed

We present a girl with the characteristic clinical picture associated with Marden-Walker syndrome (MWS; OMIM 248700), including mask-like face with blepharophimosis, joint contractures, intellectual disability, a multicystic dysplastic kidney and cerebral dysgenesis. The long-term follow-up allowed us to monitor the evolution of the phenotype in this patient, and among the main findings we highlight the following: demyelination of the pyramidal tract demonstrated by transcranial magnetic stimulation and the involvement of the levator muscles of angle of mouth in fixed facial expression with relative integrity of the rest of the facial expression muscles. A 244 k array comparative genomic hybridization (aCGH) was carried out and showed a de novo interstitial deletion of approximately 2.84 Mb affecting only the cytoband 21q22.11 (genome coordinates chr21:31,874,016-34,711,763). We selected 10 of the most recent published cases with either total or partial deletions of cytoband 21q22.11 that provided good characterization of the genomic size or the genes in the deleted regions. We observed that in nine of the 10 cases the deleted regions included the RUNX1 gene in 21q22.12, which is not affected in the current patient's deletion or in that of Patient 3 from Roberson et al. [2011]. After a comparison of shared deleted genes between cases, and correlation of their potential phenotypes, we concluded that the pattern of defects considered for a diagnosis of MWS may represent part of the phenotypic expression of a partial or total deletion of 21q22.11. PMID:23894067

Carrascosa-Romero, María Carmen; Suela, Javier; Pardal-Fernández, José Manuel; Bermejo-Sánchez, Eva; Vidal-Company, Alberto; MacDonald, Alexandra; Tébar-Gil, Roque; Martínez-Fernández, María Luisa; Martínez-Frías, María Luisa

2013-09-01

421

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

422

1 Misconceptions in Halliday, Resnick and Walker’s textbook  

E-print Network

By perusing several University Physics textbooks [1], [2], [3], [4], I was astonished with the inclusion in those textbooks of misconceptions dealing with Relativity, Gravitation and Cosmology. I have to confess that all the cited textbooks can be recommended for freshmen University students and the overall picture is that the books cited are all excellent, except

Editora Albert; Marcelo Samuel Berman

2005-01-01

423

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

PubMed Central

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

2013-01-01

424

Fault Slip Partitioning in the Eastern California Shear Zone-Walker Lane Belt: Pliocene to Late Pleistocene Contraction Across the Mina Deflection  

NASA Astrophysics Data System (ADS)

Two different mechanisms have been proposed for fault slip transfer between the subparallel NW-striking dextral- slip faults that dominant the Eastern California Shear Zone (ECSZ)-Walker Lane Belt (WLB). In the northern WLB, domains of sinistral-slip along NE-striking faults and clockwise block rotation within a zone of distributed deformation accommodated NW-dextral shear. A somewhat modified version of this mechanism was also proposed for the Mina deflection, southern WLB, whereby NE-striking sinistral faults formed as conjugate faults to the primary zone of NW-dextral shear; clockwise rotation of the blocks bounding the sinistral faults accommodated dextral slip. In contrast, in the northern ECSZ and Mina deflection, domains of NE-striking pure dip-slip normal faults, bounded by NW-striking dextral-slip faults, exhibited no rotation; the proposed mechanism of slip transfer was one of right-stepping, high angle normal faults in which the magnitude of extension was proportional to the amount of strike-slip motion transferred. New geologic mapping, tectonic geomorphologic, and geochronologic data from the Queen Valley area, southern Mina deflection constrain Pliocene to late Quaternary fault geometries, slip orientations, slip magnitudes, and slip rates that bear on the mechanism of fault slip transfer from the relatively narrow northern ECSZ to the broad deformation zone that defines the Mina deflection. Four different fault types and orientations cut across the Queen Valley area: (1) The NE-striking normal-slip Queen Valley fault; (2) NE-striking sinistral faults; (3) the NW-striking dextral Coyote Springs fault, which merges into (4) a set of EW-striking thrust faults. (U-Th)/He apatite and cosmogenic radionuclide data, combined with magnitude of fault offset measurements, indicate a Pliocene to late Pleistocene horizontal extension rate of 0.2-0.3 mm/yr across the Queen Valley fault. Our results, combined with published slip rates for the dextral White Mountain fault zone (0.3-0.8 mm/yr) and the eastern sinistral Coaldale fault (0.4 mm/yr) suggest that transfer of dextral slip from the narrow White Mountains fault zone is explained best by a simple shear couple whereby slip is partitioned into three different components: horizontal extension along the Queen Valley fault, dominantly dextral slip along the Coyote Springs fault, and dominantly sinistral slip along the Coaldale fault. A velocity vector diagram illustrating fault slip partitioning predicts contraction rates of <0.1 to 0.5 mm/yr across the Coyote Springs and western Coaldale faults. The predicted long-term contraction across the Mina deflection is consistent with present-day GPS data.

Lee, J.; Stockli, D.; Gosse, J.

2007-12-01

425

July 13, 2007 Mark Walker  

E-print Network

involved with Northwest electric system planning and the design and implementation of energy efficiency the entirety of available and cost-effective electric energy efficiency, as required by the 1980 Northwest of the fact that energy efficiency programs planned and implemented under the Council's guidance for the last

426

November 19, 2004 Mark Walker  

E-print Network

refers to advanced digital technology that improves the efficiency of electrical networks and links new of the region's electric energy efficiency potential. Approximately half of the region's forecast growth over and rate stability to electricity consumers, growth opportunities to energy efficiency product

427

Self-assembled granular walkers  

E-print Network

Mechanisms of locomotion in microscopic systems are of great interest not only for technological applications, but also for the sake of understanding, and potentially harnessing, processes far from thermal equilibrium. Down-scaling is a particular challenge, and has led to a number of interesting concepts including thermal ratchet systems and asymmetric swimmers. Here we present a system which is particularly intriguing, as it is self-assembling and uses a robust mechanism which can be implemented in various settings. It consists of small spheres of different size which adhere to each other, and are subject to an oscillating (zero average) external force eld. An inherent nonlinearity in the mutual force network leads to force rectication and hence to locomotion. We present a model that accounts for the observed behaviour and demonstrates the wide applicability and potential scalability of the concept.

Z. S. Khan; A. Steinberger; R. Seemann; and S. Herminghaus

2010-03-08

428

Disease Precautions for Dog Walkers  

MedlinePLUS

... Awards Veterinary Education Economics & Practice Economics & Finance Practice Management Client Materials Insurance Advocacy National Issues State & Local Issues Get Involved Meetings & Events AVMA Annual Convention Veterinary Leadership Conference Future AVMA Meeting Dates Meetings & CE Calendar ...

429

October 2, 2006 Mark Walker  

E-print Network

their unique needs and circumstances. While there are likely common coordination functions among all coordination proposal against another. The CRITFC proposal does include some common activities as indicated

430

November 18, 2004 Mark Walker  

E-print Network

is especially important in light of the fact that Bonneville's role in meeting the region's load growth may for meeting load growth and on what terms." 11-3. In our comments to the Council last April on its the science underlying climate change, the range of potential responses (carbon tax, carbon emissions standard

431

April 23, 2004 Mark Walker  

E-print Network

's Future Role April 23, 2004 Page 2 of 14 Allocation Of The Existing System From SUB's perspective, it makes some sense both legally and politically, to allocate the BPA system based on critical water

432

October 5, 2006 Mark Walker  

E-print Network

on behalf of this imperiled native species. Specifically, a NWPCC decision to eliminate funding support of streams, large rivers, and slow-moving water is one of only two native Washington turtle species, a species is slowly coming back from the brink of extinction! But, given the continued presence of non-native

433

Daniel Walker 12 February 2014  

E-print Network

White- A. transmontanus } 8 of 27 species of acipenserids } Lower conservation concern than Eurasian-Siskiyou Wildlands Center. Green sturgeon (Acipenser medirostris). http:// kswild.org/what-we-do-2/biodiversity/green-sturgeon-acipenser, Acipenser oxyrynchus. http://upload.wikimedia.org/ wikipedia/commons/b/b8/Acipenser

Gray, Matthew

434

July 11, 2008 Mark Walker  

E-print Network

and recover fish and wildlife in the region. While we support a proposal to have the Council monitor to report on ocean conditions and ocean productivity. The large variability in salmon survivals in the ocean

435

Can in situ methanogenesis explain a 3 m-thick gas hydrate-filled sand in Walker Ridge Block 313, Gulf of Mexico?  

NASA Astrophysics Data System (ADS)

In the spring of 2009, the Gulf of Mexico Gas Hydrate Joint Industry Project (JIP) Leg II drilled several holes in the Gulf of Mexico in the search for gas hydrate-filled reservoirs. In Walker Ridge Block 313, Hole H was drilled in a location where the gas hydrate stability zone (GHSZ) extended over 800 meters below seafloor (mbsf). For this research, we will focus on gas hydrate found in Hole H in a thick accumulation in fine-grained sediments (180-320 mbsf) as well as in a 3 m sand (292-295 mbsf). In the thick fine-grained accumulation, logging-while-drilling resistivity images show gas hydrate occurs predominately as fill in near-vertical fractures (dipping 77 degrees on average). Gas hydrates are likely to occupy 5 or 10% of the total pore volume in the fractured interval. No electrically conductive (water-filled fractures) were identified in the gas hydrate-filled fracture interval or elsewhere in Hole H. The fractures occur regularly throughout the 180-320 mbsf interval, except between 282-302 mbsf, where no fractures appear. A 3 m-thick gas hydrate-filled sand occurs in the middle of the fracture hiatus, from 292-295 mbsf. The 3 m sand has an approximate gas hydrate saturation of 70% of pore space, much higher than the fractures. Other JIP scientists have traced this 3 m-thick sand on 3D seismic sections, and found that it intersects the base of the GHSZ approximately 3 km downdip. In addition, the intersection between the sand and the gas hydrate stability zone has a reflection phase reversal, suggesting that the sand may contain gas hydrate over 3 km. Could the gas that supplies the 3 m sand have traveled updip through the GHSZ in the 3 m sand? Alternatively, the gas that supplies the sand and the fractures may be formed in place by in situ methanogenesis. Dissolved methane may diffuse from the surrounding fine-grained sediments into the sand, increasing the concentration of gas hydrate in the sand, while leaving surrounding fine-grained sediments devoid of gas hydrate. Similar situations - where gas hydrates form in coarse-grained layers but not in surrounding fine-grained sediments - are found in several locations worldwide. In this research, we are building a 1-dimensional diagenetic model that reproduces the conditions at Hole H. The model will test if enough biogenic methane is present to fill the 3 m-thick sand to the observed gas hydrate saturation. Additionally, this model will determine if the hiatus in gas hydrate-bearing fractures surrounding the sand can be explained by diffusion of methane from the fine-grained sediments into the sand.

Cook, A.; Malinverno, A.

2010-12-01

436

Bone mass and geometry of the tibia and the radius of master sprinters, middle and long distance runners, race-walkers and sedentary control participants: A pQCT study  

PubMed Central

Mechanical loading is thought to be a determinant of bone mass and geometry. Both ground reaction forces and tibial strains increase with running speed. This study investigates the hypothesis that surrogates of bone strength in male and female master sprinters, middle and long distance runners and race-walkers vary according to discipline-specific mechanical loading from sedentary controls. Bone scans were obtained by peripheral Quantitative Computed Tomography (pQCT) from the tibia and from the radius in 106 sprinters, 52 middle distance runners, 93 long distance runners and 49 race-walkers who were competing at master championships, and who were aged between 35 and 94 years. Seventy-five age-matched, sedentary people served as control group. Most athletes of this study had started to practice their athletic discipline after the age of 20, but the current training regime had typically been maintained for more than a decade. As hypothesised, tibia diaphyseal bone mineral content (vBMC), cortical area and polar moment of resistance were largest in sprinters, followed in descending order by middle and long distance runners, race-walkers and controls. When compared to control people, the differences in these measures were always > 13% in male and > 23% in female sprinters (p < 0.001). Similarly, the periosteal circumference in the tibia shaft was larger in male and female sprinters by 4% and 8%, respectively, compared to controls (p < 0.001). Epiphyseal group differences were predominantly found for trabecular vBMC in both male and female sprinters, who had 15% and 18% larger values, respectively, than controls (p < 0.001). In contrast, a reverse pattern was found for cortical vBMD in the tibia, and only few group differences of lower magnitude were found between athletes and control people for the radius. In conclusion, tibial bone strength indicators seemed to be related to exercise-specific peak forces, whilst cortical density was inversely related to running distance. These results may be explained in two, non-exclusive ways. Firstly, greater skeletal size may allow larger muscle forces and power to be exerted, and thus bias towards engagement in athletics. Secondly, musculoskeletal forces related to running can induce skeletal adaptation and thus enhance bone strength. PMID:19332164

Wilks, D.C.; Winwood, K.; Gilliver, S.F.; Kwiet, A.; Chatfield, M.; Michaelis, I.; Sun, L.W.; Ferretti, J.L.; Sargeant, A.J.; Felsenberg, D.; Rittweger, J.

2009-01-01

437

Walker, C. P., Maerz, N., and Hilgers, M. G. 2005. Surface reconstruction using shadow profilometry. Proceedings of the 2005 ACM Symposium on Applied Computing (Santa Fe, New Mexico, March 13 -17, 2005). L. M. Leibrock, Ed. SAC '05. ACM Press, New York,  

E-print Network

potential in application to post- disaster forensic investigations. The underlying concept is to reconstructWalker, C. P., Maerz, N., and Hilgers, M. G. 2005. Surface reconstruction using shadow profilometry. Leibrock, Ed. SAC '05. ACM Press, New York, NY, pp. 1250-1251. Surface Reconstruction Using Shadow

Maerz, Norbert H.

438

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

PubMed

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

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

2010-11-01

439

Interaction between the Bound Mg•ATP and the Walker A Serine Residue in NBD2 of Multidrug Resistance-Associated Protein MRP1 Plays a Crucial Role for the ATP-Dependent Leukotriene C4 Transport†  

PubMed Central

Structural analysis of human MRP1-NBD1 revealed that the Walker A S685 forms a hydrogen bond with the Walker B D792 and interacts with the Mg2+ cofactor and the ?-phosphate of the bound Mg•ATP. We have found that substitution of the S685 with an amino acid that potentially prevents the formation of the hydrogen bond resulted in misfolding of the protein and significantly affect the ATP-dependent leukotriene C4 (LTC4) transport. In this report we tested whether the corresponding substitution in NBD2 would also result in misfolding of the protein. In contrast to the NBD1 mutations, none of the mutations in NBD2, including S1334A, S1334C, S1334D, S1334H, S1334N, and S1334T, caused misfolding of the protein. However, elimination of the hydroxyl group at S1334 in mutations including S1334A, S1334C, S1334D, S1334H, and S1334N drastically reduced the ATP binding and the ATP-enhanced ADP trapping at the mutated NBD2. Due to this low efficient ATP binding at the mutated NBD2, the inhibitory effect of ATP on the LTC4 binding is significantly decreased. Furthermore, ATP bound to the mutated NBD2 cannot be efficiently hydrolyzed, leading to almost completely abolishing the ATP-dependent LTC4 transport. In contrast, S1334T mutation, which retained the hydroxyl group at this position, exerts higher LTC4 transport activity than the wild-type MRP1, indicating that the hydroxyl group at this position plays a crucial role for ATP binding/hydrolysis and ATP-dependent solute transport. PMID:18636743

Yang, Runying; Scavetta, Robert; Chang, Xiu-bao

2012-01-01

440

Why Regulate? Peter Walker -Director, Technology OFTEL  

E-print Network

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Haddadi, Hamed