What makes the family of barred disc galaxies so rich: damping stellar bars in spinning haloes

NASA Astrophysics Data System (ADS)

Collier, Angela; Shlosman, Isaac; Heller, Clayton

2018-05-01

We model and analyse the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ˜ 0-0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes - spherical, oblate, and prolate. We find that stellar bars experience a diverse evolution that is guided by the ability of parent haloes to absorb angular momentum, J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonant J-transfer to the halo. Our main findings relate to the long-term secular evolution of disc-halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) the vertical buckling instability in stellar bars colludes with inability of the inner halo to absorb J - this emerges as the main factor weakening or destroying bars in spinning haloes; (2) bars lose progressively less J, and their pattern speeds level off; (3) bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) bars in λ > 0.03 haloes have ratio of corotation-to-bar radii, RCR/Rb > 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis of J-transfer in disc-halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.

Orbital tori for non-axisymmetric galaxies

NASA Astrophysics Data System (ADS)

Binney, James

2018-02-01

Our Galaxy's bar makes the Galaxy's potential distinctly non-axisymmetric. All orbits are affected by non-axisymmetry, and significant numbers are qualitatively changed by being trapped at a resonance with the bar. Orbital tori are used to compute these effects. Thick-disc orbits are no less likely to be trapped by corotation or a Lindblad resonance than thin-disc orbits. Perturbation theory is used to create non-axisymmetric orbital tori from standard axisymmetric tori, and both trapped and untrapped orbits are recovered to surprising accuracy. Code is added to the TorusModeller library that makes it as easy to manipulate non-axisymmetric tori as axisymmetric ones. The augmented TorusModeller is used to compute the velocity structure of the solar neighbourhood for bars of different pattern speeds and a simple action-based distribution function. The technique developed here can be applied to any non-axisymmetric potential that is stationary in a rotating from - hence also to classical spiral structure.

Tidally Induced Bars of Galaxies in Clusters

NASA Astrophysics Data System (ADS)

Łokas, Ewa L.; Ebrová, Ivana; del Pino, Andrés; Sybilska, Agnieszka; Athanassoula, E.; Semczuk, Marcin; Gajda, Grzegorz; Fouquet, Sylvain

2016-08-01

Using N-body simulations, we study the formation and evolution of tidally induced bars in disky galaxies in clusters. Our progenitor is a massive, late-type galaxy similar to the Milky Way, composed of an exponential disk and a Navarro-Frenk-White dark matter halo. We place the galaxy on four different orbits in a Virgo-like cluster and evolve it for 10 Gyr. As a reference case, we also evolve the same model in isolation. Tidally induced bars form on all orbits soon after the first pericenter passage and survive until the end of the evolution. They appear earlier, are stronger and longer, and have lower pattern speeds for tighter orbits. Only for the tightest orbit are the properties of the bar controlled by the orientation of the tidal torque from the cluster at pericenter. The mechanism behind the formation of the bars is the angular momentum transfer from the galaxy stellar component to its halo. All of the bars undergo extended periods of buckling instability that occur earlier and lead to more pronounced boxy/peanut shapes when the tidal forces are stronger. Using all simulation outputs of galaxies at different evolutionary stages, we construct a toy model of the galaxy population in the cluster and measure the average bar strength and bar fraction as a function of clustercentric radius. Both are found to be mildly decreasing functions of radius. We conclude that tidal forces can trigger bar formation in cluster cores, but not in the outskirts, and thus can cause larger concentrations of barred galaxies toward the cluster center.

Discrete wavelet transform and energy eigen value for rotor bars fault detection in variable speed field-oriented control of induction motor drive.

PubMed

Ameid, Tarek; Menacer, Arezki; Talhaoui, Hicham; Azzoug, Youness

2018-05-03

This paper presents a methodology for the broken rotor bars fault detection is considered when the rotor speed varies continuously and the induction machine is controlled by Field-Oriented Control (FOC). The rotor fault detection is obtained by analyzing a several mechanical and electrical quantities (i.e., rotor speed, stator phase current and output signal of the speed regulator) by the Discrete Wavelet Transform (DWT) in variable speed drives. The severity of the fault is obtained by stored energy calculation for active power signal. Hence, it can be a useful solution as fault indicator. The FOC is implemented in order to preserve a good performance speed control; to compensate the broken rotor bars effect in the mechanical speed and to ensure the operation continuity and to investigate the fault effect in the variable speed. The effectiveness of the technique is evaluated in simulation and in a real-time implementation by using Matlab/Simulink with the real-time interface (RTI) based on dSpace 1104 board. Copyright © 2018. Published by Elsevier Ltd.

Formation of Tidally Induced Bars in Galactic Flybys: Prograde versus Retrograde Encounters

NASA Astrophysics Data System (ADS)

Łokas, Ewa L.

2018-04-01

Bars in disk galaxies can be formed by interactions with other systems, including those of comparable mass. It has long been established that the effect of such interactions on galaxy morphology depends strongly on the orbital configuration, in particular the orientation of the intrinsic spin of the galactic disk with respect to its orbital angular momentum. Prograde encounters modify the morphology strongly, including the formation of tidally induced bars, while retrograde flybys should have little effect on morphology. Recent works on the subject reached conflicting conclusions, one using the impulse approximation and claiming no dependence on this angle in the properties of tidal bars. To resolve the controversy, we performed self-consistent N-body simulations of hyperbolic encounters between two identical Milky Way-like galaxies assuming different velocities and impact parameters, with one of the galaxies on a prograde and the other on a retrograde orbit. The galaxies were initially composed of an exponential stellar disk and an NFW dark halo, and they were stable against bar formation in isolation for 3 Gyr. We find that strong tidally induced bars form only in galaxies on prograde orbits. For smaller impact parameters and lower relative velocities, the bars are stronger and have lower pattern speeds. Stronger bars undergo extended periods of buckling instability that thicken their vertical structure. The encounters also lead to the formation of two-armed spirals with strength inversely proportional to the strength of the bars. We conclude that proper modeling of prograde and retrograde encounters cannot rely on the simplest impulse approximation.

Time-of-Flight Measurement of the Speed of Sound in a Metal Bar

ERIC Educational Resources Information Center

Ganci, Salvatore

2016-01-01

A simple setup was designed for a "time-of-flight" measurement of the sound speed in a metal bar. The experiment requires low cost components and is very simple to understand by students. A good use of it is as a demonstration experiment.

The flow in the spiral arms of slowly rotating bar-spiral models

NASA Astrophysics Data System (ADS)

Patsis, P. A.; Tsigaridi, L.

2017-07-01

We use response models to study the stellar and gaseous flows in the spiral arm regions of slow rotating barred-spiral potentials. We vary the pattern speed so that the corotation-to bar radius ratios (Rc/Rb) are in the range 2 < Rc/Rb < 3. We find in general two sets of spirals, one inside and one outside corotation, which are reinforced by two different dynamical mechanisms. The bar and the spirals inside corotation are supported by regular orbits, while the spirals beyond corotation are associated with the "chaotic spirals", both in the stellar as well as in the gaseous case. The main difference in the two flows is the larger dispersion of velocities we encounter in the stellar (test-particles) models. The inner and the outer spirals are in general not connected. In most cases we find an oval component inside corotation, that surrounds the inner barred-spiral structure and separates it from the outer spirals. In the gaseous models, clumps of local overdensities are formed along the inner arms as the gas shocks in the spirals region, while clumps in the spirals beyond corotation are formed as the flows along the two outer arms meet and join each other close to the unstable Lagrangian points of the system.

Aeolian sand transport over complex intertidal bar-trough beach topography

NASA Astrophysics Data System (ADS)

Anthony, Edward J.; Ruz, Marie-Hélène; Vanhée, Stéphane

2009-04-01

Aeolian sand transport on macrotidal beaches with complex intertidal bar-trough topography (ridge-and-runnel beaches) was assessed from experiments in northern France that involved measurements of wind speed, saltation, surface moisture contents, and rates of sand trapping across surveyed portions of the upper beach profile. Beaches exhibiting intertidal bars and troughs are much more complex, topographically, than simple reflective or dissipative beaches. Furthermore, the intertidal bar-trough morphology commonly exhibits strong cross-shore variations in the moisture contents of the beach surface and in patterns of bedform development. The results of four 30-minute experiments, conducted along topographically surveyed portions of the upper beach-dune toe profile, show that troughs act as extremely efficient sand interceptors, because of their permanently saturated state, which also inhibits sand mobilisation. Troughs, thus, limit or segment the dry fetch during conditions of intermittent saltation. Flow lines, inferred from the wind profiles, suggest that complex interactions at the boundary layer are generated by the bar-trough topography. Troughs systematically appear to be characterised by air expansion, while bar faces generate ramp wind acceleration for onshore winds, and sometimes immediate downwind deceleration for offshore winds. These effects may also contribute to cross-shore variations in the rates of sand trapping. Finally, a simple conceptual model of effective fetch development, integrating the effects of the spring-neap tidal range and of gross bar-trough morphological variability over time, is proposed for bar-trough beaches. The model highlights the key theme of fetch segmentation induced by cross-shore differentiation in the moisture contents of the beach surface hinged on the complex topography of multiple bars and troughs.

Contribution of Leg-Muscle Forces to Paddle Force and Kayak Speed During Maximal-Effort Flat-Water Paddling.

PubMed

Nilsson, Johnny E; Rosdahl, Hans G

2016-01-01

The purpose was to investigate the contribution of leg-muscle-generated forces to paddle force and kayak speed during maximal-effort flat-water paddling. Five elite male kayakers at national and international level participated. The participants warmed up at progressively increasing speeds and then performed a maximal-effort, nonrestricted paddling sequence. This was followed after 5 min rest by a maximal-effort paddling sequence with the leg action restricted--the knee joints "locked." Left- and right-side foot-bar and paddle forces were recorded with specially designed force devices. In addition, knee angular displacement of the right and left knees was recorded with electrogoniometric technique, and the kayak speed was calculated from GPS signals sampled at 5 Hz. The results showed that reduction in both push and pull foot-bar forces resulted in a reduction of 21% and 16% in mean paddle-stroke force and mean kayak speed, respectively. Thus, the contribution of foot-bar force from lower-limb action significantly contributes to kayakers' paddling performance.

Uncovering the origins of spiral structure through the measurement of pattern speeds and their radial variation

NASA Astrophysics Data System (ADS)

Meidt, Sharon E.

At the intersection of galactic dynamics, evolution and global structure, unresolved issues in the nature and origin of spirals can be addressed through the characterization of the angular speeds of the patterns and their possible radial variation. In this thesis I describe the development, testing, and application of the Radial Tremaine-Weinberg (TWR) Method, a generalized version of the continuity-based TW method wherein the pattern speed is allowed to vary arbitrarily with radius. I will address the utility of, and caveats in applying, the TWR calculation together with a standard regularization technique in a series of tests on N- body simulations. The regularization, which smooths otherwise intrinsically noisy solutions based on a priori assumptions for the radial dependence of the pattern speed, proves to be essential for achieving the radial precision necessary for accurate measurement. I also present results from applications of the TWR method to observations of real galaxies, where the possible sources and sinks in the continuity equation are well understood. Using CO observations of the grand design galaxy M51, the TWR method reveals a heretofore un-measured inner spiral pattern speed for the bright two-armed spiral structure, with a value significantly higher than conventional estimates. In addition, the radial dependence implied in the TWR solution suggests a possible resonant link between the inner and outer regions of the bright spiral arms. These findings signify an advance in observational investigations into the nature and origin of grand-design spiral structure. By analyzing high-quality HI and CO data cubes available for four other spiral galaxies, the characteristic signatures of the processes that drive spiral structure are likewise identifiable; within this small sample, the first direct evidence for the presence of resonant coupling of multiple distinct patterns is found in some galaxies, while a simple single pattern speed is measured in others. I conclude with a summary of future avenues for investigation with the TWR method and propose additional modifications of the TW calculation with which the influence of bar and spiral structure on the evolution of galaxy disks can be directly characterized.

75 FR 27925 - Use of Turkey Shackle in Bar-Type Cut Operations; Correcting Amendment

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-19

...-0045] Use of Turkey Shackle in Bar-Type Cut Operations; Correcting Amendment AGENCY: Food Safety and... the required shackle width for Bar-type cut turkey operations that use J-type cut maximum line speeds... provides that turkey slaughter establishments that open turkey carcasses with Bar-type cuts may operate at...

Rolling-element fatigue life with traction fluids and automatic transmission fluid in a high-speed rolling-contact rig

NASA Technical Reports Server (NTRS)

Parker, R. J.; Nahm, A. H.; Loewenthal, S. H.

1982-01-01

Rolling-element fatigue tests were run in standard and high-speed rolling-contact rigs at bar speeds from 5000 to 50,000 rpm to determine the effects of speed and lubricant film parameter on rolling-element fatigue life. AISI 52100 test bars were tested at a maximum Hertz stress of 4.83 GPa (700,000 psi) with three traction fluids and an automatic transmission fluid. Rolling-element fatigue life increased with speed, with the greatest increases occurring from 10,000 to 50,000 rpm. The life data tended to follow published life-versus-lubricant-film-parameter data up to a film parameter of approximately 3.

Explaining the footsteps, belly dancer, Wenceslas, and kickback illusions.

PubMed

Howe, Piers D L; Thompson, Peter G; Anstis, Stuart M; Sagreiya, Hersh; Livingstone, Margaret S

2006-12-12

The footsteps illusion (FI) demonstrates that an object's background can have a profound effect on the object's perceived speed. This illusion consists of a yellow bar and a blue bar that move over a black-and-white, striped background. Although the bars move at a constant rate, they appear to repeatedly accelerate and decelerate in antiphase with each other. Previously, this illusion has been explained in terms of the variations in contrast at the leading and trailing edges of the bars that occur as the bars traverse the striped background. Here, we show that this explanation is inadequate and instead propose that for each bar, the bar's leading edge, trailing edge, lateral edges, and the surrounding background edges all contribute to the bar's perceived speed and that the degree to which each edge contributes to the motion percept is determined by that edge's contrast. We show that this theory can explain all the data on the FI as well as the belly dancer and Wenceslas illusions. We conclude by presenting a new illusion, the kickback illusion, which, although geometrically similar to the FI, is mediated by a different mechanism, namely, reverse phi motion.

Relation of sortable silt grain-size to deep-sea current speeds: Calibration of the 'Mud Current Meter'

NASA Astrophysics Data System (ADS)

McCave, I. N.; Thornalley, D. J. R.; Hall, I. R.

2017-09-01

Fine grain-size parameters have been used for inference of palaeoflow speeds of near-bottom currents in the deep-sea. The basic idea stems from observations of varying sediment size parameters on a continental margin with a gradient from slower flow speeds at shallower depths to faster at deeper. In the deep-sea, size-sorting occurs during deposition after benthic storm resuspension events. At flow speeds below 10-15 cm s-1 mean grain-size in the terrigenous non-cohesive 'sortable silt' range (denoted by SS bar , mean of 10-63 μm) is controlled by selective deposition, whereas above that range removal of finer material by winnowing is also argued to play a role. A calibration of the SS bar grain-size flow speed proxy based on sediment samples taken adjacent to sites of long-term current meters set within 100 m of the sea bed for more than a year is presented here. Grain-size has been measured by either Sedigraph or Coulter Counter, in some cases both, between which there is an excellent correlation for SS bar (r = 0.96). Size-speed data indicate calibration relationships with an overall sensitivity of 1.36 ± 0.19 cm s-1/μm. A calibration line comprising 12 points including 9 from the Iceland overflow region is well defined, but at least two other smaller groups (Weddell/Scotia Sea and NW Atlantic continental rise/Rockall Trough) are fitted by sub-parallel lines with a smaller constant. This suggests a possible influence of the calibre of material supplied to the site of deposition (not the initial source supply) which, if depleted in very coarse silt (31-63 μm), would limit SS bar to smaller values for a given speed than with a broader size-spectrum supply. Local calibrations, or a core-top grain-size and local flow speed, are thus necessary to infer absolute speeds from grain-size. The trend of the calibrations diverges markedly from the slope of experimental critical erosion and deposition flow speeds versus grain-size, making it unlikely that the SS bar (or any deposit size for that matter) is simply predicted by the deposition threshold. A more probable control is the rate of deposition of the different size fractions under changing flows over several tens of years (the typical averaging period of a centimetre of deposited sediment). This suggestion is supported by a simple depositional model for which the deposited SS bar is calculated from measured currents with a size-varying depositional threshold. More surficial sediment samples taken near long-term current meter sites are needed to make calibrations more robust and explore regional differences.

Transverse speed bars for rural traffic calming.

DOT National Transportation Integrated Search

2013-10-01

Small rural communities often lack the expertise and resources necessary to address speeding and the persistent challenge of slowing high-speed through traffic. The entrances to communities are especially problematic given that drivers must transitio...

Bar dimensions and bar shapes in estuaries

NASA Astrophysics Data System (ADS)

Leuven, Jasper; Kleinhans, Maarten; Weisscher, Steven; van der Vegt, Maarten

2016-04-01

Estuaries cause fascinating patterns of dynamic channels and shoals. Intertidal sandbars are valuable habitats, whilst channels provide access to harbors. We still lack a full explanation and classification scheme for the shapes and dimensions of bar patterns in natural estuaries, in contrast with bars in rivers. Analytical physics-based models suggest that bar length in estuaries increases with flow velocity, tidal excursion length or estuary width, depending on which model. However, these hypotheses were never validated for lack of data and experiments. We present a large dataset and determine the controls on bar shape and dimensions in estuaries, spanning bar lengths from centimeters (experiments) to 10s of kilometers length. First, we visually identified and classified 190 bars, measured their dimensions (width, length, height) and local braiding index. Data on estuarine geometry and tidal characteristics were obtained from governmental databases and literature on case studies. We found that many complex bars can be seen as simple elongated bars partly cut by mutually evasive ebb- and flood-dominated channels. Data analysis shows that bar dimensions scale with estuary dimensions, in particular estuary width. Breaking up the complex bars in simple bars greatly reduced scatter. Analytical bar theory overpredicts bar dimensions by an order of magnitude in case of small estuarine systems. Likewise, braiding index depends on local width-to-depth ratio, as was previously found for river systems. Our results suggest that estuary dimensions determine the order of magnitude of bar dimensions, while tidal characteristics modify this. We will continue to model bars numerically and experimentally. Our dataset on tidal bars enables future studies on the sedimentary architecture of geologically complex tidal deposits and enables studying effects of man-induced perturbations such as dredging and dumping on bar and channel patterns and habitats.

Temporal ventriloquism along the path of apparent motion: speed perception under different spatial grouping principles.

PubMed

Ogulmus, Cansu; Karacaoglu, Merve; Kafaligonul, Hulusi

2018-03-01

The coordination of intramodal perceptual grouping and crossmodal interactions plays a critical role in constructing coherent multisensory percepts. However, the basic principles underlying such coordinating mechanisms still remain unclear. By taking advantage of an illusion called temporal ventriloquism and its influences on perceived speed, we investigated how audiovisual interactions in time are modulated by the spatial grouping principles of vision. In our experiments, we manipulated the spatial grouping principles of proximity, uniform connectedness, and similarity/common fate in apparent motion displays. Observers compared the speed of apparent motions across different sound timing conditions. Our results revealed that the effects of sound timing (i.e., temporal ventriloquism effects) on perceived speed also existed in visual displays containing more than one object and were modulated by different spatial grouping principles. In particular, uniform connectedness was found to modulate these audiovisual interactions in time. The effect of sound timing on perceived speed was smaller when horizontal connecting bars were introduced along the path of apparent motion. When the objects in each apparent motion frame were not connected or connected with vertical bars, the sound timing was more influential compared to the horizontal bar conditions. Overall, our findings here suggest that the effects of sound timing on perceived speed exist in different spatial configurations and can be modulated by certain intramodal spatial grouping principles such as uniform connectedness.

Testing of an actively damped boring bar featuring structurally integrated PZT stack actuators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Redmond, J.; Barney, P.

This paper summarizes the results of cutting tests performed using an actively damped boring bar to minimize chatter in metal cutting. A commercially available 2 inch diameter boring bar was modified to incorporate PZT stack actuators for controlling tool bending vibrations encountered during metal removal. The extensional motion of the actuators induce bending moments in the host structure through a two-point preloaded mounting scheme. Cutting tests performed at various speeds and depths of cuts on a hardened steel workpiece illustrate the bar`s effectiveness toward eliminating chatter vibrations and improving workpiece surface finish.

Walking Speed Influences the Effects of Implicit Visual Feedback Distortion on Modulation of Gait Symmetry

PubMed Central

Maestas, Gabrielle; Hu, Jiyao; Trevino, Jessica; Chunduru, Pranathi; Kim, Seung-Jae; Lee, Hyunglae

2018-01-01

The use of visual feedback in gait rehabilitation has been suggested to promote recovery of locomotor function by incorporating interactive visual components. Our prior work demonstrated that visual feedback distortion of changes in step length symmetry entails an implicit or unconscious adaptive process in the subjects’ spatial gait patterns. We investigated whether the effect of the implicit visual feedback distortion would persist at three different walking speeds (slow, self-preferred and fast speeds) and how different walking speeds would affect the amount of adaption. In the visual feedback distortion paradigm, visual vertical bars portraying subjects’ step lengths were distorted so that subjects perceived their step lengths to be asymmetric during testing. Measuring the adjustments in step length during the experiment showed that healthy subjects made spontaneous modulations away from actual symmetry in response to the implicit visual distortion, no matter the walking speed. In all walking scenarios, the effects of implicit distortion became more significant at higher distortion levels. In addition, the amount of adaptation induced by the visual distortion was significantly greater during walking at preferred or slow speed than at the fast speed. These findings indicate that although a link exists between supraspinal function through visual system and human locomotion, sensory feedback control for locomotion is speed-dependent. Ultimately, our results support the concept that implicit visual feedback can act as a dominant form of feedback in gait modulation, regardless of speed. PMID:29632481

Large velocity dispersion of molecular gas in bars of strongly barred galaxies NGC 1300 and NGC 5383

NASA Astrophysics Data System (ADS)

Maeda, Fumiya; Ohta, Kouji; Fujimoto, Yusuke; Habe, Asao; Baba, Junichi

2018-06-01

We carried out ^{12}CO(J = 1-0) observations toward bar and arm regions of the strongly barred galaxies NGC 1300 and NGC 5383 with the Nobeyama 45 m radio telescope (beam size of 1-2 kpc in the galaxies). The aim of the observations is to qualitatively examine a new scenario for the suppression of star formation in bars based on recent high-resolution numerical simulations: higher speed collisions between molecular clouds in the bar region compared with the arm region suppress the massive star formation. CO emissions were detected from all the regions, indicating the presence of molecular gases in the strong bars without associating clear H II regions. In both galaxies, the velocity width of the CO line profile tends to be larger in the bar region than in the arm region, which is qualitatively consistent with the new scenario.

A design of high-precision BLDCM drive with bus voltage protection

NASA Astrophysics Data System (ADS)

Lian, Xuezheng; Wang, Haitao; Xie, Meilin; Huang, Wei; Li, Dawei; Jing, Feng

2017-11-01

In the application of space satellite turntable, the design of balance wheel is very necessary. To solve the acquisition precision of Brushless DC motor speed is low, and the encoder is also more complex, this paper improves the original hall signal measurement methods. Using the logic device to achieve the six frequency multiplication of hall signal, the signal is used as speed feedback to achieve speed closed-loop control and improve the speed stability. At the same time, in order to prevent the E.M.F of BLDC motor to raise the voltage of the bus bar when reversing or braking, and affect the normal operation of other circuit modules, the analog circuit is used to protect the bus bar voltage by the way of energy consumption braking. The experimental results are consistent with the theoretical design, and the rationality and feasibility of the frequency multiplication scheme and bus voltage protection scheme are verified.

An Analysis of Information Assurance Relating to the Department of Defense Radio Frequency Identification (RFID) Passive Network

DTIC Science & Technology

2005-03-01

codes speed up consumer shopping, package shipping, and inventory tracking. RFID offers many advantages over bar codes, as the table below shows...sunlight” (Accenture, 2001, p. 4). Finally, one of the most significant advantages of RFID is the advent of anti-collision. Anti-collision allows an...RFID reader to read and/or write to multiple tags at one time, which is not possible for bar codes. Despite the many advantages RFID over bar codes

Technological Enhancements for Personal Computers

DTIC Science & Technology

1992-03-01

quicker order processing , shortening the time required to obtain critical spare parts. 31 Customer service and spare parts tracking are facilitated by...cards speed up order processing and filing. Bar code readers speed inventory control processing. D. DEPLOYMENT PLANNING. Many units with high mobility

Fast Fourier and discrete wavelet transforms applied to sensorless vector control induction motor for rotor bar faults diagnosis.

PubMed

Talhaoui, Hicham; Menacer, Arezki; Kessal, Abdelhalim; Kechida, Ridha

2014-09-01

This paper presents new techniques to evaluate faults in case of broken rotor bars of induction motors. Procedures are applied with closed-loop control. Electrical and mechanical variables are treated using fast Fourier transform (FFT), and discrete wavelet transform (DWT) at start-up and steady state. The wavelet transform has proven to be an excellent mathematical tool for the detection of the faults particularly broken rotor bars type. As a performance, DWT can provide a local representation of the non-stationary current signals for the healthy machine and with fault. For sensorless control, a Luenberger observer is applied; the estimation rotor speed is analyzed; the effect of the faults in the speed pulsation is compensated; a quadratic current appears and used for fault detection. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

RESONANT CLUMPING AND SUBSTRUCTURE IN GALACTIC DISKS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molloy, Matthew; Smith, Martin C.; Shen, Juntai

2015-05-10

We describe a method to extract resonant orbits from N-body simulations, exploiting the fact that they close in frames rotating with a constant pattern speed. Our method is applied to the N-body simulation of the Milky Way by Shen et al. This simulation hosts a massive bar, which drives strong resonances and persistent angular momentum exchange. Resonant orbits are found throughout the disk, both close to the bar and out to the very edges of the disk. Using Fourier spectrograms, we demonstrate that the bar is driving kinematic substructure even in the very outer parts of the disk. We identifymore » two major orbit families in the outskirts of the disk, one of which makes significant contributions to the kinematic landscape, namely, the m:l = 3:−2 family, resonating with the bar. A mechanism is described that produces bimodal distributions of Galactocentric radial velocities at selected azimuths in the outer disk. It occurs as a result of the temporal coherence of particles on the 3:−2 resonant orbits, which causes them to arrive simultaneously at pericenter or apocenter. This resonant clumping, due to the in-phase motion of the particles through their epicycle, leads to both inward and outward moving groups that belong to the same orbital family and consequently produce bimodal radial velocity distributions. This is a possible explanation of the bimodal velocity distributions observed toward the Galactic anticenter by Liu et al. Another consequence is that transient overdensities appear and dissipate (in a symmetric fashion), resulting in a periodic pulsing of the disk’s surface density.« less

PERFORMANCE OF RC AND FRC WALL PANELS REINFORCED WITH MILD STEEL AND GFRP COMPOSITES IN BLAST EVENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timothy Garfield; William D. Richins; Thomas K. Larson

The structural integrity of reinforced concrete structures in blast events is important for critical facilities. This paper presents experimental data generated for calibrating detailed finite element models that predict the performance of reinforced concrete wall panels with a wide range of construction details under blast loading. The test specimens were 1.2 m square wall panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consists of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bar reinforcement (Type A); FRC panels without additional reinforcement (Type B); FRC panels with steel barmore » reinforcement (Type C); NWC panels with glass fiber reinforced polymer (GFRP) bar reinforcement (Type D); and NWC panels reinforced with steel bar reinforcement and external bidirectional GFRP overlays on both faces (Type E). An additional three Type C panels were used as control specimens (CON). Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. The panels were instrumented with strain gauges, and accelerometers; in addition, pressure sensors and high speed videos were employed during the blast events. Panel types C and E had the best performance, whereas panel type B did not perform well. Preliminary dynamic simulations show crack patterns similar to the experimental results.« less

A model-based approach for the scattering-bar printing avoidance

NASA Astrophysics Data System (ADS)

Du, Yaojun; Li, Liang; Zhang, Jingjing; Shao, Feng; Zuniga, Christian; Deng, Yunfei

2018-03-01

As the technology node for the semiconductor manufacturing approaches advanced nodes, the scattering-bars (SBs) are more crucial than ever to ensure a good on-wafer printability of the line space pattern and hole pattern. The main pattern with small pitches requires a very narrow PV (process variation) band. A delicate SB addition scheme is thus needed to maintain a sufficient PW (process window) for the semi-iso- and iso-patterns. In general, the wider, longer, and closer to main feature SBs will be more effective in enhancing the printability; on the other hand, they are also more likely to be printed on the wafer; resulting in undesired defects transferable to subsequent processes. In this work, we have developed a model based approach for the scattering-bar printing avoidance (SPA). A specially designed optical model was tuned based on a broad range of test patterns which contain a variation of CDs and SB placements showing printing and non-printing scattering bars. A printing threshold is then obtained to check the extra-printings of SBs. The accuracy of this threshold is verified by pre-designed test patterns. The printing threshold associated with our novel SPA model allows us to set up a proper SB rule.

The dual function of barred plumage in birds: camouflage and communication.

PubMed

Gluckman, T L; Cardoso, G C

2010-11-01

A commonly held principle in visual ecology is that communication compromises camouflage: while visual signals are often conspicuous, camouflage provides concealment. However, some traits may have evolved for communication and camouflage simultaneously, thereby overcoming this functional compromise. Visual patterns generally provide camouflage, but it was suggested that a particular type of visual pattern – avian barred plumage – could also be a signal of individual quality. Here, we test if the evolution of sexual dimorphism in barred plumage, as well as differences between juvenile and adult plumage, indicate camouflage and/or signalling functions across the class Aves. We found a higher frequency of female- rather than male-biased sexual dimorphism in barred plumage, indicating that camouflage is its most common function. But we also found that, compared to other pigmentation patterns, barred plumage is more frequently biased towards males and its expression more frequently restricted to adulthood, suggesting that barred plumage often evolves or is maintained as a sexual communication signal. This illustrates how visual traits can accommodate the apparently incompatible functions of camouflage and communication, which has implications for our understanding of avian visual ecology and sexual ornamentation.

Dynamics of the interstellar matter in galaxies : isolated barred spiral galaxies : cloud formation processes

NASA Astrophysics Data System (ADS)

Helmuth, Kristen

1998-12-01

The dynamical components of six isolated barred spiral (SB) galaxies are investigated. No evidence is found supporting the hypothesis of a low amount of dark matter being characteristic of SB galaxies. The presence of companion galaxies is found to correlate with an increased statistical spread in the neutral hydrogen (HI) extent. It is concluded that the selection of galaxies with large HI extent may introduce a bias towards tidally interacting systems. The circumnuclear region of the SB galaxy NGC 1365 is studied with the Hubble Space Telescope (HST). Numerous bright "super star clusters" (SSCs) are detected, surrounding the active nucleus. The bright compact radio source NGC 1365:A is found to coincide spatially with one of the SSCs. We conclude that the source is a "radio supernova". In the [OIII] l 5007 line, the HST resolves individual clouds within the conical outflow from the nucleus, some of which gather in larger agglomerations. An in-depth study of the dynamics of the SB galaxy NGC 1300 is presented. Multi-wavelength data yield an estimate of the velocity field and gravitational potential. Subsequent hydrodynamical simulations are able to reproduce the morphology and kinematics in the bar region using a pure bar perturbing potential. To reproduce the spiral structure a weak spiral component has to be added, indicative of stellar spiral response to the bar and/or self-gravitating gas in the arms. Two separate models, differing mainly with respect to pattern speed and associated resonance structure, are found to reproduce the observations. We study numerically the linear polarization and extinction of light from background stars passing through molecular clouds, illuminating the intricacies of the derivation of the magnetic-field-line pattern in a cloud from the observed polarization pattern: Due to a higher gas-grain collision frequency within the cloud, the polarization caused by the cloud may well be dominated by background/foreground polarization. Furthermore, variations in field-orientation along the line-of-sight may cause notable differences between the observed polarization vectors and the true magnetic-field-line pattern. Small-scale, helical, interstellar filaments are discussed on the basis of optical observations of an "elephant trunk" structure in the Rosette nebula. The observed sinusoidal filaments are suggested to be helices lined up by magnetic fields. We propose that the Rosette elephant trunks form an interconnected system of rope-like structures which are relics from filamentary skeletons of magnetic fields in the primordial cloud. Stochastic mass fractionation of a molecular cloud is simulated numerically. It is found that geometry alone may constrain the resulting mass spectrum of molecular cloud clumps. We demonstrate that further fragmentation of the cloud clumps, under the assumption of a lower limit of the self-similar regime, produces a mass spectrum that has qualitative and quantitative similarities with the empirically determined stellar initial mass function.

Evaluation of data from test application of optical speed bars to highway work zones

DOT National Transportation Integrated Search

2004-08-01

The proximity of traffic and workers in highway work zones demand that safety be a high priority. : The issue of traffic speeds in highway work zones has long been an issue receiving much attention. Over the : past three decades, many different measu...

Method of Evaluating Hydrogen Embrittlement Susceptibility of Tempered Martensitic Steel Showing Intergranular Fracture

NASA Astrophysics Data System (ADS)

Matsumoto, Yu; Takai, Kenichi

2018-02-01

A stress application method in delayed fracture susceptibility tests was investigated using 1450 MPa class tempered martensitic steel. Its fracture mode under hydrogen charging was mainly intergranular because of its relatively small Si content of 0.21 mass pct. The conditions for consistency in fracture strength between tensile tests and constant load tests (CLTs) were clarified: first, to conduct hydrogen precharging before stress application; and second, to choose a sufficiently low crosshead speed in tensile tests. When hydrogen precharging was not conducted before CLTs, the fracture strength was higher than the values in CLTs with hydrogen charging and in tensile tests. If the crosshead speed was too high, the fracture strength obtained was higher than the values in CLTs. The dependence of the fracture strength on crosshead speed was seen for both notched and smooth bar specimens. These results suggested that plastic deformation, i.e., dislocation motion, was related to intergranular fracture with a tear pattern as well as to quasi-cleavage fracture. In addition, cathodic electrolysis in an alkaline solution containing NaOH should be used as the hydrogen charging method to avoid the effects of corrosion.

Development of a New Method to Investigate the Dynamic Friction Behavior of Interfaces Using a Kolsky Tension Bar

DOE PAGES

Sanborn, B.; Song, B.; Nishida, E.

2017-11-02

In order to understand interfacial interaction of a bi-material during an impact loading event, the dynamic friction coefficient is one of the key parameters that must be characterized and quantified. In this study, a new experimental method to determine the dynamic friction coefficient between two metals was developed by using a Kolsky tension bar and a custom-designed friction fixture. Polyvinylidene fluoride (PVDF) force sensors were used to measure the normal force applied to the friction tribo pairs and the friction force was measured with conventional Kolsky tension bar method. To evaluate the technique, the dynamic friction coefficient between 4340 steelmore » and 7075-T6 aluminum was investigated at an impact speed of approximately 8 m/s. Additionally, the dynamic friction coefficient of the tribo pairs with varied surface roughness was also investigated. The data suggest that higher surface roughness leads to higher friction coefficients at the same speed of 8 m/s.« less

Experiments and Demonstrations in Physics: Bar-Ilan Physics Laboratory (2nd Edition)

NASA Astrophysics Data System (ADS)

Kraftmakher, Yaakov

2014-08-01

The following sections are included: * Data-acquisition systems from PASCO * ScienceWorkshop 750 Interface and DataStudio software * 850 Universal Interface and Capstone software * Mass on spring * Torsional pendulum * Hooke's law * Characteristics of DC source * Digital storage oscilloscope * Charging and discharging a capacitor * Charge and energy stored in a capacitor * Speed of sound in air * Lissajous patterns * I-V characteristics * Light bulb * Short time intervals * Temperature measurements * Oersted's great discovery * Magnetic field measurements * Magnetic force * Magnetic braking * Curie's point I * Electric power in AC circuits * Faraday's law of induction I * Self-inductance and mutual inductance * Electromagnetic screening * LCR circuit I * Coupled LCR circuits * Probability functions * Photometric laws * Kirchhoff's rule for thermal radiation * Malus' law * Infrared radiation * Irradiance and illuminance

PCR-free quantitative detection of genetically modified organism from raw materials. An electrochemiluminescence-based bio bar code method.

PubMed

Zhu, Debin; Tang, Yabing; Xing, Da; Chen, Wei R

2008-05-15

A bio bar code assay based on oligonucleotide-modified gold nanoparticles (Au-NPs) provides a PCR-free method for quantitative detection of nucleic acid targets. However, the current bio bar code assay requires lengthy experimental procedures including the preparation and release of bar code DNA probes from the target-nanoparticle complex and immobilization and hybridization of the probes for quantification. Herein, we report a novel PCR-free electrochemiluminescence (ECL)-based bio bar code assay for the quantitative detection of genetically modified organism (GMO) from raw materials. It consists of tris-(2,2'-bipyridyl) ruthenium (TBR)-labeled bar code DNA, nucleic acid hybridization using Au-NPs and biotin-labeled probes, and selective capture of the hybridization complex by streptavidin-coated paramagnetic beads. The detection of target DNA is realized by direct measurement of ECL emission of TBR. It can quantitatively detect target nucleic acids with high speed and sensitivity. This method can be used to quantitatively detect GMO fragments from real GMO products.

Bar represses dPax2 and decapentaplegic to regulate cell fate and morphogenetic cell death in Drosophila eye.

PubMed

Kang, Jongkyun; Yeom, Eunbyul; Lim, Janghoo; Choi, Kwang-Wook

2014-01-01

The coordinated regulation of cell fate and cell survival is crucial for normal pattern formation in developing organisms. In Drosophila compound eye development, crystalline arrays of hexagonal ommatidia are established by precise assembly of diverse cell types, including the photoreceptor cells, cone cells and interommatidial (IOM) pigment cells. The molecular basis for controlling the number of cone and IOM pigment cells during ommatidial pattern formation is not well understood. Here we present evidence that BarH1 and BarH2 homeobox genes are essential for eye patterning by inhibiting excess cone cell differentiation and promoting programmed death of IOM cells. Specifically, we show that loss of Bar from the undifferentiated retinal precursor cells leads to ectopic expression of Prospero and dPax2, two transcription factors essential for cone cell specification, resulting in excess cone cell differentiation. We also show that loss of Bar causes ectopic expression of the TGFβ homolog Decapentaplegic (Dpp) posterior to the morphogenetic furrow in the larval eye imaginal disc. The ectopic Dpp expression is not responsible for the formation of excess cone cells in Bar loss-of-function mutant eyes. Instead, it causes reduction in IOM cell death in the pupal stage by antagonizing the function of pro-apoptotic gene reaper. Taken together, this study suggests a novel regulatory mechanism in the control of developmental cell death in which the repression of Dpp by Bar in larval eye disc is essential for IOM cell death in pupal retina.

Effect of twist on transverse impact response of ballistic fiber yarns

DOE PAGES

Song, Bo; Lu, Wei -Yang

2015-06-15

A Hopkinson bar was employed to conduct transverse impact testing of twisted Kevlar KM2 fiber yarns at the same impact speed. The speed of Euler transverse wave generated by the impact was measured utilizing a high speed digital camera. The study included fiber yarns twisted by different amounts. The Euler transverse wave speed was observed to increase with increasing amount of twist of the fiber yarn, within the range of this investigation. As a result, the higher transverse wave speeds in the more twisted fiber yarns indicate better ballistic performance in soft body armors for personal protection.

Crowding by a single bar: probing pattern recognition mechanisms in the visual periphery.

PubMed

Põder, Endel

2014-11-06

Whereas visual crowding does not greatly affect the detection of the presence of simple visual features, it heavily inhibits combining them into recognizable objects. Still, crowding effects have rarely been directly related to general pattern recognition mechanisms. In this study, pattern recognition mechanisms in visual periphery were probed using a single crowding feature. Observers had to identify the orientation of a rotated T presented briefly in a peripheral location. Adjacent to the target, a single bar was presented. The bar was either horizontal or vertical and located in a random direction from the target. It appears that such a crowding bar has very strong and regular effects on the identification of the target orientation. The observer's responses are determined by approximate relative positions of basic visual features; exact image-based similarity to the target is not important. A version of the "standard model" of object recognition with second-order features explains the main regularities of the data. © 2014 ARVO.

Performance simulation of BaBar DIRC bar boxes in TORCH

NASA Astrophysics Data System (ADS)

Föhl, K.; Brook, N.; Castillo García, L.; Cussans, D.; Forty, R.; Frei, C.; Gao, R.; Gys, T.; Harnew, N.; Piedigrossi, D.; Rademacker, J.; Ros García, A.; van Dijk, M.

2017-12-01

TORCH is a large-area precision time-of-flight detector based on the DIRC principle. The DIRC bar boxes of the BaBar experiment at SLAC could possibly be reused to form a part of the TORCH detector time-of-flight wall area, proposed to provide positive particle identification of low momentum kaons in the LHCb experiment at CERN. For a potential integration of BaBar bar boxes into TORCH, new imaging readout optics are required. From the several designs of readout optics that have been considered, two are used in this paper to study the effect of BaBar bar optical imperfections on the detector reconstruction performance. The kaon-pion separation powers obtained from analysing simulated photon hit patterns show the performance reduction for a BaBar bar of non-square geometry compared to a perfectly rectangular cross section.

Barred owl space use and habitat selection in the eastern Cascades, Washington

Treesearch

Peter J. Singleton; John F. Lehnkuhl; William L. Gaines; Scott A. Graham

2010-01-01

Competition with barred owls (Strix varia varia) is an important factor contributing to the continued decline of threatened northern spotted owl (Strix occidentalis caurina) populations in the Pacific Northwest, USA, but basic information on habitat selection and space use patterns of barred owls is lacking for much of the...

Determining the speed of sound in the air by sound wave interference

NASA Astrophysics Data System (ADS)

Silva, Abel A.

2017-07-01

Mechanical waves propagate through material media. Sound is an example of a mechanical wave. In fluids like air, sound waves propagate through successive longitudinal perturbations of compression and decompression. Audible sound frequencies for human ears range from 20 to 20 000 Hz. In this study, the speed of sound v in the air is determined using the identification of maxima of interference from two synchronous waves at frequency f. The values of v were correct to 0 °C. The experimental average value of {\\bar{ν }}\\exp =336 +/- 4 {{m}} {{{s}}}-1 was found. It is 1.5% larger than the reference value. The standard deviation of 4 m s-1 (1.2% of {\\bar{ν }}\\exp ) is an improved value by the use of the concept of the central limit theorem. The proposed procedure to determine the speed of sound in the air aims to be an academic activity for physics classes of scientific and technological courses in college.

Factorial analysis of diesel engine performance using different types of biofuels.

PubMed

Tashtoush, Ghassan M; Al-Widyan, Mohamad I; Albatayneh, Aiman M

2007-09-01

In this study, several bio-source-fuels like fresh and waste vegetable oil and waste animal fat were tested at different injector pressures (120, 140, 190, 210 bar) in a direct-injection, naturally aspirated, single-cylinder diesel engine with a design injection pressure of 190 bar. Using 2k factorial analysis, the effect of injection pressure (Pi) and fuel type on three engine parameters, namely, combustion efficiency (etac), mass fuel consumption (mf), and engine speed (N) was examined. It was found that Pi and fuel type significantly affected both etac and mf while they had a slight effect on engine speed. Moreover, with diesel and biodiesels, the etac increased to a maximum at 190 bar but declined at the higher Pi value. In contrast, higher Pi had a favorable effect on etac over the whole Pi range with all the other more viscous fuels tested. In addition, the mass fuel consumption consistently decreased with an increase in Pi for all the fuels including the baseline diesel fuel, with which the engine consistently attained higher etac and higher rpm compared to all the other fuels tested.

Hummingbirds generate bilateral vortex loops during hovering: evidence from flow visualization

NASA Astrophysics Data System (ADS)

Pournazeri, Sam; Segre, Paolo S.; Princevac, Marko; Altshuler, Douglas L.

2012-12-01

Visualization of the vortex wake of a flying animal provides understanding of how wingbeat kinematics are translated into the aerodynamic forces for powering and controlling flight. Two general vortex flow patterns have been proposed for the wake of hovering hummingbirds: (1) The two wings form a single, merged vortex ring during each wing stroke; and (2) the two wings form bilateral vortex loops during each wing stroke. The second pattern was proposed after a study with particle image velocimetry that demonstrated bilateral source flows in a horizontal measurement plane underneath hovering Anna's hummingbirds ( Calypte anna). Proof of this hypothesis requires a clear perspective of bilateral pairs of vortices. Here, we used high-speed image sequences (500 frames per second) of C. anna hover feeding within a white plume to visualize the vortex wake from multiple perspectives. The films revealed two key structural features: (1) Two distinct jets of downwards airflow are present under each wing; and (2) vortex loops around each jet are shed during each upstroke and downstroke. To aid in the interpretation of the flow visualization data, we analyzed high-speed kinematic data (1,000 frames per second) of wing tips and wing roots as C. anna hovered in normal air. These data were used to refine several simplified models of vortex topology. The observed flow patterns can be explained by either a single loop model with an hourglass shape or a bilateral model, with the latter being more likely. When hovering in normal air, hummingbirds used an average stroke amplitude of 153.6° (range 148.9°-164.4°) and a wingbeat frequency of 38.5 Hz (range 38.1-39.1 Hz). When hovering in the white plume, hummingbirds used shallower stroke amplitudes ( bar{x} = 129.8°, range 116.3°-154.1°) and faster wingbeat frequencies ( bar{x} = 41.1 Hz, range 38.5-44.7 Hz), although the bilateral jets and associated vortices were observed across the full kinematic range. The plume did not significantly alter the air density or constrain the sustained muscle contractile frequency. Instead, higher wingbeat frequencies likely incurred a higher metabolic cost with the possible benefit of allowing the birds to more rapidly escape from the visually disruptive plume.

Hummingbirds generate bilateral vortex loops during hovering: evidence from flow visualization

NASA Astrophysics Data System (ADS)

Pournazeri, Sam; Segre, Paolo S.; Princevac, Marko; Altshuler, Douglas L.

2013-01-01

Visualization of the vortex wake of a flying animal provides understanding of how wingbeat kinematics are translated into the aerodynamic forces for powering and controlling flight. Two general vortex flow patterns have been proposed for the wake of hovering hummingbirds: (1) The two wings form a single, merged vortex ring during each wing stroke; and (2) the two wings form bilateral vortex loops during each wing stroke. The second pattern was proposed after a study with particle image velocimetry that demonstrated bilateral source flows in a horizontal measurement plane underneath hovering Anna's hummingbirds ( Calypte anna). Proof of this hypothesis requires a clear perspective of bilateral pairs of vortices. Here, we used high-speed image sequences (500 frames per second) of C. anna hover feeding within a white plume to visualize the vortex wake from multiple perspectives. The films revealed two key structural features: (1) Two distinct jets of downwards airflow are present under each wing; and (2) vortex loops around each jet are shed during each upstroke and downstroke. To aid in the interpretation of the flow visualization data, we analyzed high-speed kinematic data (1,000 frames per second) of wing tips and wing roots as C. anna hovered in normal air. These data were used to refine several simplified models of vortex topology. The observed flow patterns can be explained by either a single loop model with an hourglass shape or a bilateral model, with the latter being more likely. When hovering in normal air, hummingbirds used an average stroke amplitude of 153.6° (range 148.9°-164.4°) and a wingbeat frequency of 38.5 Hz (range 38.1-39.1 Hz). When hovering in the white plume, hummingbirds used shallower stroke amplitudes ( bar{x} = 129.8°, range 116.3°-154.1°) and faster wingbeat frequencies ( bar{x} = 41.1 Hz, range 38.5-44.7 Hz), although the bilateral jets and associated vortices were observed across the full kinematic range. The plume did not significantly alter the air density or constrain the sustained muscle contractile frequency. Instead, higher wingbeat frequencies likely incurred a higher metabolic cost with the possible benefit of allowing the birds to more rapidly escape from the visually disruptive plume.

A Regularization Approach to Blind Deblurring and Denoising of QR Barcodes.

PubMed

van Gennip, Yves; Athavale, Prashant; Gilles, Jérôme; Choksi, Rustum

2015-09-01

QR bar codes are prototypical images for which part of the image is a priori known (required patterns). Open source bar code readers, such as ZBar, are readily available. We exploit both these facts to provide and assess purely regularization-based methods for blind deblurring of QR bar codes in the presence of noise.

Simultaneous multiscale measurements on dynamic deformation of a magnesium alloy with synchrotron x-ray imaging and diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, L.; Sun, T.; Fezzaa, K.

Dynamic split Hopkinson pressure bar experiments with in situ synchrotron x-ray imaging and diffraction are conducted on a rolled magnesium alloy at high strain rates of ~5500 s-1. High speed multiscale measurements including stress–strain curves (macroscale), strain fields (mesoscale), and diffraction patterns (microscale) are obtained simultaneously, revealing strong anisotropy in deformation across different length scales. {1012} extension twinning induces homogenized strain fields and gives rise to rapid increase in strain hardening rate, while dislocation motion leads to inhomogeneous deformation and a decrease in strain hardening rate. During the early stage of plastic deformation, twinning is dominant in dynamic compression, whilemore » dislocation motion prevails in quasi-static loading, manifesting a strain-rate dependence of deformation.« less

Accurate D-bar Reconstructions of Conductivity Images Based on a Method of Moment with Sinc Basis.

PubMed

Abbasi, Mahdi

2014-01-01

Planar D-bar integral equation is one of the inverse scattering solution methods for complex problems including inverse conductivity considered in applications such as Electrical impedance tomography (EIT). Recently two different methodologies are considered for the numerical solution of D-bar integrals equation, namely product integrals and multigrid. The first one involves high computational burden and the other one suffers from low convergence rate (CR). In this paper, a novel high speed moment method based using the sinc basis is introduced to solve the two-dimensional D-bar integral equation. In this method, all functions within D-bar integral equation are first expanded using the sinc basis functions. Then, the orthogonal properties of their products dissolve the integral operator of the D-bar equation and results a discrete convolution equation. That is, the new moment method leads to the equation solution without direct computation of the D-bar integral. The resulted discrete convolution equation maybe adapted to a suitable structure to be solved using fast Fourier transform. This allows us to reduce the order of computational complexity to as low as O (N (2)log N). Simulation results on solving D-bar equations arising in EIT problem show that the proposed method is accurate with an ultra-linear CR.

Molecularly imprinted polymeric stir bar: Preparation and application for the determination of naftopidil in plasma and urine samples.

PubMed

Peng, Jun; Xiao, Deli; He, Hua; Zhao, Hongyan; Wang, Cuixia; Shi, Tian; Shi, Kexin

2016-01-01

In this study, molecularly imprinting technology and stir bar absorption technology were combined to develop a microextraction approach based on a molecularly imprinted polymeric stir bar. The molecularly imprinted polymer stir bar has a high performance, is specific, economical, and simple to prepare. The obtained naftopidil-imprinted polymer-coated bars could simultaneously agitate and adsorb naftopidil in the sample solution. The ratio of template/monomer/cross-linker and conditions of template removal were optimized to prepare a stir bar with highly efficient adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, selectivity, and extraction capacity experiments showed that the molecularly imprinted polymer stir bar was prepared successfully. To utilize the molecularly imprinted polymer stir bar for the determination of naftopidil in complex body fluid matrices, the extraction time, stirring speed, eluent, and elution time were optimized. The limits of detection of naftopidil in plasma and urine sample were 7.5 and 4.0 ng/mL, respectively, and the recoveries were in the range of 90-112%. The within-run precision and between-run precision were acceptable (relative standard deviation <7%). These data demonstrated that the molecularly imprinted polymeric stir bar based microextraction with high-performance liquid chromatography was a convenient, rapid, efficient, and specific method for the precise determination of trace naftopidil in clinical analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An exploratory study of drug use in bar environments

PubMed Central

Trocki, Karen; Michalak, Laurence; McDaniel, Patricia

2010-01-01

The purpose of this paper is to explore the characteristics of bars where drug use was observed compared to those where no drug use was observed. The study was done through a combination of qualitative and quantitative techniques gleaned through observations and interviews. Among the most important of indicators were the type of activity (particularly dancing) and the level of rowdiness evident in the bars. In addition drug use bars had higher levels of other types of rule-breaking. Patron characteristics (more men) and behavioral patterns (more sexual risk-taking) also distinguished these bars. PMID:25221431

Speed skills: measuring the visual speed analyzing properties of primate MT neurons.

PubMed

Perrone, J A; Thiele, A

2001-05-01

Knowing the direction and speed of moving objects is often critical for survival. However, it is poorly understood how cortical neurons process the speed of image movement. Here we tested MT neurons using moving sine-wave gratings of different spatial and temporal frequencies, and mapped out the neurons' spatiotemporal frequency response profiles. The maps typically had oriented ridges of peak sensitivity as expected for speed-tuned neurons. The preferred speed estimate, derived from the orientation of the maps, corresponded well to the preferred speed when moving bars were presented. Thus, our data demonstrate that MT neurons are truly sensitive to the object speed. These findings indicate that MT is not only a key structure in the analysis of direction of motion and depth perception, but also in the analysis of object speed.

Hang Gliders for Sport

NASA Technical Reports Server (NTRS)

1976-01-01

Hang gliding is growing rapidly. Free Flight produces 1,000 gliders a month and other companies are entering the field. Wing is simple to control, pulling back on control bar allows you to pick up speed and at the same time lowers your altitude. Pushing forward slows your speed and levels you off. Birdmen can choose from prone, upright or swing seat harnesses in either kits or ready-to-fly gliders.

Comparative analysis of the gastrointestinal microbial communities of bar-headed goose (Anser indicus) in different breeding patterns by high-throughput sequencing.

PubMed

Wang, Wen; Cao, Jian; Li, Ji-Rong; Yang, Fang; Li, Zhuo; Li, Lai-Xing

2016-01-01

The bar-headed goose is currently one of the most popular species for rare birds breeding in China. However, bar-headed geese in captivity display a reduced reproductive rate. The gut microbiome has been shown to influence host factors such as nutrient and energy metabolism, immune homeostasis and reproduction. It is therefore of great scientific and agriculture value to analyze the microbial communities associated with bar-headed geese in order to improve their reproductive rate. Here we describe the first comparative study of the gut microbial communities of bar-headed geese in three different breeding pattern groups by 16SrRNA sequences using the Illumina MiSeq platform. The results showed that Firmicutes predominated (58.33%) among wild bar-headed geese followed by Proteobacteria (30.67%), Actinobacteria (7.33%) and Bacteroidetes (3.33%). In semi-artificial breeding group, Firmicutes was also the most abundant bacteria (62.00%), followed by Bacteroidetes (28.67%), Proteobacteria (4.20%), Actinobacteria (3.27%) and Fusobacteria (1.51%). The microbial communities of artificial breeding group were dominated by Firmicutes (60.67%), Fusobacteria (29.67%) and Proteobacteria (9.33%). Wild bar-headed geese had a significant higher relative abundance of Proteobacteria and Actinobacteria, while semi-artificial breeding bar-headed geese had significantly more Bacteroidetes. The semi-artificial breeding group had the highest microbial community diversity and richness, followed by wild group, and then the artificial breeding group. The marked differences of genus level group-specific microbes create a baseline for future bar-headed goose microbiology research. Copyright © 2015 Elsevier GmbH. All rights reserved.

Development of a Mobile Robot with Wavy Movement by Rotating Bars

NASA Astrophysics Data System (ADS)

Kitagawa, Ato; Zhang, Liang; Eguchi, Takashi; Tsukagoshi, Hideyuki

A mobile robot with a new type of movement called wavy movement is proposed in this paper. Wavy movement can be readily realized by many bars or crosses which are rotating at equivalent speeds, and the robot with simple structure and easy control method is able to ascend and descend stairs by covering the corners of stairs within separate wave shapes between touching points. The principle of wavy movement, the mechanism, and the experimental result of the proposed robot are discussed.

Jump Squat is More Related to Sprinting and Jumping Abilities than Olympic Push Press.

PubMed

Loturco, I; Kobal, R; Maldonado, T; Piazzi, A F; Bottino, A; Kitamura, K; Abad, C C C; Pereira, L A; Nakamura, F Y

2017-07-01

The aim of this study was to test the relationships between jump squat (JS) and Olympic push press (OPP) power outputs and performance in sprint, squat jump (SJ), countermovement jump (CMJ) and change of direction (COD) speed tests in elite soccer players. 27 athletes performed a maximum power load test to determine their bar mean propulsive power (MPP) and bar mean propulsive velocity (MPV) in the JS and OPP exercises. Magnitude-based inference was used to compare the exercises. The MPV was almost certainly higher in the OPP than in the JS. The MPP relative to body mass (MPP REL) was possibly higher in the OPP. Only the JS MPP REL presented very large correlations with linear speed ( r> 0.7, for speed in 5, 10, 20 and 30 m) and vertical jumping abilities ( r> 0.8, for SJ and CMJ), and moderate correlation with COD speed ( r= 0.45). Although significant (except for COD), the associations between OPP outcomes and field-based measurements (speed, SJ and CMJ) were all moderate, ranging from 0.40 to 0.48. In a group composed of elite soccer players, the JS exercise is more associated with jumping and sprinting abilities than the OPP. Longitudinal studies are needed to confirm if these strong relationships imply superior training effects in favor of the JS exercise. © Georg Thieme Verlag KG Stuttgart · New York.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, B.; Nelson, K.; Lipinski, R.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less

Dynamics of the Interstellar Matter in Galaxies

NASA Astrophysics Data System (ADS)

Kristen, H.

The dynamical components of six isolated barred spiral (SB) galaxies are investigated. No evidence is found supporting the hypothesis of a low amount of dark matter being characteristic of SB galaxies. The presence of companion galaxies is found to correlate with an increased statistical spread in the neutral hydrogen (HI) extent. It is concluded that the selection of galaxies with large HI~extent may introduce a bias towards tidally interacting systems. The circumnuclear region of the SB galaxy NGC 1365 is studied with the Hubble Space Telescope (HST). Numerous bright ``super star clusters'' (SSCs) are detected, surrounding the active nucleus. The bright compact radio source NGC 1365:A is found to coincide spatially with one of the SSCs. We conclude that the source is a ``radio supernova''. In the [OIII] 5007 line, the HST resolves individual clouds within the conical outflow from the nucleus, some of which gather in larger agglomerations. An in-depth study of the dynamics of the SB galaxy NGC 1300 is presented. Multi-wavelength data yield an estimate of the velocity field and gravitational potential. Subsequent hydrodynamical simulations are able to reproduce the morphology and kinematics in the bar region using a pure bar perturbing potential. To reproduce the spiral structure a weak spiral component has to be added, indicative of stellar spiral response to the bar and/or self-gravitating gas in the arms. Two separate models, differing mainly with respect to pattern speed and associated resonance structure, are found to reproduce the observations. We study numerically the linear polarization and extinction of light from background stars passing through molecular clouds, illuminating the intricacies of the derivation of the magnetic-field-line pattern in a cloud from the observed polarization pattern: Due to a higher gas-grain collision frequency within the cloud, the polarization caused by the cloud may well be dominated by background/foreground polarization. Furthermore, variations in field-orientation along the line-of-sight may cause notable differences between the observed polarization vectors and the true magnetic-field-line pattern. Small-scale, helical, interstellar filaments are discussed on the basis of optical observations of an ``elephant trunk'' structure in the Rosette nebula. The observed sinusoidal filaments are suggested to be helices lined up by magnetic fields. We propose that the Rosette elephant trunks form an interconnected system of rope-like structures which are relics from filamentary skeletons of magnetic fields in the primordial cloud. Stochastic mass fractionation of a molecular cloud is simulated numerically. It is found that geometry alone may constrain the resulting mass spectrum of molecular cloud clumps. We demonstrate that further fragmentation of the cloud clumps, under the assumption of a lower limit of the self-similar regime, produces a mass spectrum that has qualitative and quantitative similarities with the empirically determined stellar initial mass function.

Modeling And Simulation Of Bar Code Scanners Using Computer Aided Design Software

NASA Astrophysics Data System (ADS)

Hellekson, Ron; Campbell, Scott

1988-06-01

Many optical systems have demanding requirements to package the system in a small 3 dimensional space. The use of computer graphic tools can be a tremendous aid to the designer in analyzing the optical problems created by smaller and less costly systems. The Spectra Physics grocery store bar code scanner employs an especially complex 3 dimensional scan pattern to read bar code labels. By using a specially written program which interfaces with a computer aided design system, we have simulated many of the functions of this complex optical system. In this paper we will illustrate how a recent version of the scanner has been designed. We will discuss the use of computer graphics in the design process including interactive tweaking of the scan pattern, analysis of collected light, analysis of the scan pattern density, and analysis of the manufacturing tolerances used to build the scanner.

Numerical modeling of the autumnal thermal bar

NASA Astrophysics Data System (ADS)

Tsydenov, Bair O.

2018-03-01

The autumnal riverine thermal bar of Kamloops Lake has been simulated using atmospheric data from December 1, 2015, to January 4, 2016. The nonhydrostatic 2.5D mathematical model developed takes into account the diurnal variability of the heat fluxes and wind on the lake surface. The average values for shortwave and longwave radiation and latent and sensible heat fluxes were 19.7 W/m2, - 95.9 W/m2, - 11.8 W/m2, and - 32.0 W/m2 respectively. Analysis of the wind regime data showed prevailing easterly winds and maximum speed of 11 m/s on the 8th and 19th days. Numerical experiments with different boundary conditions at the lake surface were conducted to evaluate effects of variable heat flux and wind stress. The results of modeling demonstrated that the variable heat flux affects the process of thermal bar evolution, especially during the lengthy night cooling. However, the wind had the greatest impact on the behavior of the autumnal thermal bar: The easterly winds contributed to an earlier appearance of the thermal bar, but the strong winds generating the intensive circulations (the velocity of the upper lake flow increased to 6 cm/s) may destroy the thermal bar front.

Dynamic tensile characterization of a 4330 steel with kolsky bar techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Antoun, Bonnie R.; Connelly, Kevin

2010-08-01

There has been increasing demand to understand the stress-strain response as well as damage and failure mechanisms of materials under impact loading condition. Dynamic tensile characterization has been an efficient approach to acquire satisfactory information of mechanical properties including damage and failure of the materials under investigation. However, in order to obtain valid experimental data, reliable tensile experimental techniques at high strain rates are required. This includes not only precise experimental apparatus but also reliable experimental procedures and comprehensive data interpretation. Kolsky bar, originally developed by Kolsky in 1949 [1] for high-rate compressive characterization of materials, has been extended formore » dynamic tensile testing since 1960 [2]. In comparison to Kolsky compression bar, the experimental design of Kolsky tension bar has been much more diversified, particularly in producing high speed tensile pulses in the bars. Moreover, instead of directly sandwiching the cylindrical specimen between the bars in Kolsky bar compression bar experiments, the specimen must be firmly attached to the bar ends in Kolsky tensile bar experiments. A common method is to thread a dumbbell specimen into the ends of the incident and transmission bars. The relatively complicated striking and specimen gripping systems in Kolsky tension bar techniques often lead to disturbance in stress wave propagation in the bars, requiring appropriate interpretation of experimental data. In this study, we employed a modified Kolsky tension bar, newly developed at Sandia National Laboratories, Livermore, CA, to explore the dynamic tensile response of a 4330-V steel. The design of the new Kolsky tension bar has been presented at 2010 SEM Annual Conference [3]. Figures 1 and 2 show the actual photograph and schematic of the Kolsky tension bar, respectively. As shown in Fig. 2, the gun barrel is directly connected to the incident bar with a coupler. The cylindrical striker set inside the gun barrel is launched to impact on the end cap that is threaded into the open end of the gun barrel, producing a tension on the gun barrel and the incident bar.« less

Dynamic tensile characterization of a 4330-V steel with kolsky bar techniques.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Antoun, Bonnie R.; Connelly, Kevin

2010-09-01

There has been increasing demand to understand the stress-strain response as well as damage and failure mechanisms of materials under impact loading condition. Dynamic tensile characterization has been an efficient approach to acquire satisfactory information of mechanical properties including damage and failure of the materials under investigation. However, in order to obtain valid experimental data, reliable tensile experimental techniques at high strain rates are required. This includes not only precise experimental apparatus but also reliable experimental procedures and comprehensive data interpretation. Kolsky bar, originally developed by Kolsky in 1949 [1] for high-rate compressive characterization of materials, has been extended formore » dynamic tensile testing since 1960 [2]. In comparison to Kolsky compression bar, the experimental design of Kolsky tension bar has been much more diversified, particularly in producing high speed tensile pulses in the bars. Moreover, instead of directly sandwiching the cylindrical specimen between the bars in Kolsky bar compression bar experiments, the specimen must be firmly attached to the bar ends in Kolsky tensile bar experiments. A common method is to thread a dumbbell specimen into the ends of the incident and transmission bars. The relatively complicated striking and specimen gripping systems in Kolsky tension bar techniques often lead to disturbance in stress wave propagation in the bars, requiring appropriate interpretation of experimental data. In this study, we employed a modified Kolsky tension bar, newly developed at Sandia National Laboratories, Livermore, CA, to explore the dynamic tensile response of a 4330-V steel. The design of the new Kolsky tension bar has been presented at 2010 SEM Annual Conference [3]. Figures 1 and 2 show the actual photograph and schematic of the Kolsky tension bar, respectively. As shown in Fig. 2, the gun barrel is directly connected to the incident bar with a coupler. The cylindrical striker set inside the gun barrel is launched to impact on the end cap that is threaded into the open end of the gun barrel, producing a tension on the gun barrel and the incident bar.« less

An intervention study on the effect of matcha tea, in drink and snack bar formats, on mood and cognitive performance.

PubMed

Dietz, Christina; Dekker, Matthijs; Piqueras-Fiszman, Betina

2017-09-01

Matcha tea is gaining popularity throughout the world in recent years and is frequently referred to as a mood-and-brain food. Previous research has demonstrated that three constituents present in matcha tea, l-theanine, epigallocatechin gallate (EGCG), and caffeine, affect mood and cognitive performance. However, to date there are no studies assessing the effect of matcha tea itself. The present study investigates these effects by means of a human intervention study administering matcha tea and a matcha containing product. Using a randomized, placebo-controlled, single-blind study, 23 consumers participated in four test sessions. In each session, participants consumed one of the four test products: matcha tea, matcha tea bar (each containing 4g matcha tea powder), placebo tea, or placebo bar. The assessment was performed at baseline and 60min post-treatment. The participants performed a set of cognitive tests assessing attention, information processing, working memory, and episodic memory. The mood state was measured by means of a Profile of Mood States (POMS). After consuming the matcha products compared to placebo versions, there were mainly significant improvements in tasks measuring basic attention abilities and psychomotor speed in response to stimuli over a defined period of time. In contrast to expectations, the effect was barely present in the other cognitive tasks. The POMS results revealed no significant changes in mood. The influence of the food matrix was demonstrated by the fact that on most cognitive performance measures the drink format outperformed the bar format, particularly in tasks measuring speed of spatial working memory and delayed picture recognition. This study suggests that matcha tea consumed in a realistic dose can induce slight effects on speed of attention and episodic secondary memory to a low degree. Further studies are required to elucidate the influences of the food matrix. Copyright © 2017 Elsevier Ltd. All rights reserved.

Surface fatigue life of M50NiL and AISI 9310 spur gears and R C bars

NASA Technical Reports Server (NTRS)

Townsend, Dennis P.; Bamberger, Eric N.

1991-01-01

Spur gear endurance tests and rolling element surface fatigue tests were conducted to study vacuum induction melted, vacuum arc remelted (VIM-VAR) M50NiL steel for use as a gear steel in advanced aircraft applications, to determine its endurance characteristics, and to compare the results with those for standard VAR and VIM-VAR AISI 9310 gear material. Tests were conducted with spur gears and rolling contact bars manufactured from VIM-VAR M50NiL and VAR and VIM-VAR AISI 9310. The gear pitch diameter was 8.9 cm. Gear test conditions were an inlet oil temperature of 320 K, and outlet oil temperature of 350 K, a maximum Hertz stress of 1.71 GPa, and a speed of 10000 rpm. Bench rolling element fatigue tests were conducted at ambient temperatures with a bar speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa. The VIM-VAR M50NiL gears had a surface fatigue life that was 4.5 and 11.5 times that for VIM-VAR and VAR AISI 9310 gears, respectively. The surface fatigue life of the VIM-VAR M50NiL rolling contact bars was 13.2 and 21.6 times that for the VIM-VAR and VAR AISI 9310, respectively. The VIM-VAR M50NiL material was shown to have good resistance to fracture through a fatigue spall and superior fatigue life to both other gears.

Modeling and Characterization of Dynamic Failure of Soda-lime Glass Under High Speed Impact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wenning N.; Sun, Xin; Chen, Weinong W.

2012-05-27

In this paper, the impact-induced dynamic failure of a soda-lime glass block is studied using an integrated experimental/analytical approach. The Split Hopkinson Pressure Bar (SHPB) technique is used to conduct dynamic failure test of soda-lime glass first. The damage growth patterns and stress histories are reported for various glass specimen designs. Making use of a continuum damage mechanics (CDM)-based constitutive model, the initial failure and subsequent stiffness reduction of glass are simulated and investigated. Explicit finite element analyses are used to simulate the glass specimen impact event. A maximum shear stress-based damage evolution law is used in describing the glassmore » damage process under combined compression/shear loading. The impact test results are used to quantify the critical shear stress for the soda-lime glass under examination.« less

Sky Mystery

NASA Technical Reports Server (NTRS)

Rubincam, David P.

2017-01-01

I saw something extraordinary on Wednesday, 25 September 2013, at about 10:10AM local time, while in a parking lot at the NASA Goddard Space Flight Center in Greenbelt, Maryland USA (located in the suburbs of Washington, D.C., about 20 km northeast of the White House). I looked northeast at about a 45 degree angle at a cirrus cloud. The cloud was elongated horizontally from my perspective. T o my surprise I saw a band of ripples rapidly pass from right to left along the axis of the cloud. The ripples appeared dark, like a bar code, with the bars being almost vertical (see Figure 1). There appeared to be approximately 10 bars in the band. Each bar was a few degrees in length. I estimate that each bar was about 1/10 to 1/4 degree in width and the white spaces between them about the same width. I guessed that the angular speed of the band passing along the cloud was about 1/2 to 1 degree per second. A half-moon was in another part of the sky; looking at the Moon later helped me make the estimates. After a few seconds at most the band disappeared. Then a second band repeated the performance. I kept watching to see if this was going to be a periodic phenomenon, but no further bands appeared; just the two. Of course there may have been other bands passing across the cloud before I started looking. About 30 seconds to a minute after the bands disappeared, a low-flying jetliner on the usual northeast to southwest route passed almost exactly through the spot where I had seen the bands. I estimate the jetliner was a bit bigger than the full moon. My first thought was that maybe there was something wrong inside my eyes. But looking at other clouds revealed no bands. So what caused the bands? They do not seem to have been due to the exhausts on top of the nearby building, with the cloud acting as a backdrop: one would expect a continuous, disorganized shimmering instead of two separate organized bands. Moreover, there would be no reason for bands to stop unless the exhausts suddenly stopped right while I was looking at the cloud. Hence the explanation does not seem to be local. This or a similar phenomenon was photographed in France during World War II, apparently produced by distant artillery. Jones (1947) proffered the explanation that shock waves from the guns were made visible in the sky by a process akin to Schlieren photography, with the cloud apparently acting as a screen against which to view the waves. The photograph shows 3 bars, compared to the 10 or so I saw. Rather than the cloud just being a backdrop, Andrew T. Young of San Diego State University and my colleague Coerte Voorhies (private communications) point out that the bands may have been made in the cloud itself. A passing disturbance jostling the ice crystals in the cloud would change the reflection of sunlight to the observer, giving the light and dark pattern. Assuming Young and Voorhies are correct, what made the disturbance? Cirrus clouds range from approximately 4 km to approximately 13 km in height. A cloud at a 45 degree angle would be 5.7 km to 18.4 km away. For my estimated angular speeds of 1/2 to 1 degree per second and the range of cirrus heights, the linear speeds range from approximately 100 m s(exp -1)-1 to approximately 642 m s(exp -1), which is subsonic to supersonic. Supersonic speed is unlikely. Young suggests that if the disturbance was subsonic, then it may have been due to the twin vortices produced, not by the jet I saw a half-minute to a minute later, but by a previous jet on the populous route. Twin vortices would explain two bands. On the other hand, if the bands were sound waves traveling at the speed of sound, approximately 343 m s(exp -1), Voorhies notes that the range of estimated distances to the cloud and the estimated center-to-center spacing of 1/5 to 1/2 degrees between the bars give frequencies between approximately 5 Hz and approximately 17 Hz. This is in the infrasound range. Possibly a jet or other man-made disturbance produced infrasound. Another possibility is the passage of a large meteorite. The American Meteor Society reported that September 2013 was a busy month for bright meteors (http://earthsky.org/earth/u-smidwest- sees-another-bright-fireball). However, no daylight meteor was noticed near the appropriate place and time, and such a large meteor going undetected except for a lucky sighting of its infrasound signature in a cirrus cloud seems unlikely. I thank Andrew T. Young and Coerte Voorhies for their input.

Dynamic characterization of frequency response of shock mitigation of a polymethylene diisocyanate (PMDI) based rigid polyurethane foam

DOE PAGES

Song, Bo; Nelson, Kevin

2015-09-01

Kolsky compression bar experiments were conducted to characterize the shock mitigation response of a polymethylene diisocyanate (PMDI) based rigid polyurethane foam, abbreviated as PMDI foam in this study. The Kolsky bar experimental data was analyzed in the frequency domain with respect to impact energy dissipation and acceleration attenuation to perform a shock mitigation assessment on the foam material. The PMDI foam material exhibits excellent performance in both energy dissipation and acceleration attenuation, particularly for the impact frequency content over 1.5 kHz. This frequency (1.5 kHz) was observed to be independent of specimen thickness and impact speed, which may represent themore » characteristic shock mitigation frequency of the PMDI foam material under investigation. The shock mitigation characteristics of the PMDI foam material were insignificantly influenced by the specimen thickness. As a result, impact speed did have some effect.« less

Dynamic characterization of frequency response of shock mitigation of a polymethylene diisocyanate (PMDI) based rigid polyurethane foam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin

Kolsky compression bar experiments were conducted to characterize the shock mitigation response of a polymethylene diisocyanate (PMDI) based rigid polyurethane foam, abbreviated as PMDI foam in this study. The Kolsky bar experimental data was analyzed in the frequency domain with respect to impact energy dissipation and acceleration attenuation to perform a shock mitigation assessment on the foam material. The PMDI foam material exhibits excellent performance in both energy dissipation and acceleration attenuation, particularly for the impact frequency content over 1.5 kHz. This frequency (1.5 kHz) was observed to be independent of specimen thickness and impact speed, which may represent themore » characteristic shock mitigation frequency of the PMDI foam material under investigation. The shock mitigation characteristics of the PMDI foam material were insignificantly influenced by the specimen thickness. As a result, impact speed did have some effect.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Niranjan D.; Hudspeth, Matthew; Claus, Ben

Granular materials are widely used to resist impact and blast. Under these dynamic loadings, the constituent particles in the granular system fracture. To study the fracture mechanisms in brittle particles under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar apparatus. Controlled compressive loading was applied on two contacting particles using the Kolsky bar apparatus and fracture process was captured using the high speed X-ray imaging setup. Five different particles were investigated: soda-lime glass, polycrystalline silica (silicon dioxide), polycrystalline silicon, barium titanate glass, and yttrium stabilized zirconia. For both soda lime glassmore » and polycrystalline silica particles, one of the particles fragmented explosively, thus breaking into many small pieces. For Silicon and barium titanate glass particles, a finite number of cracks were observed in one of the particles causing it to fracture. For yttrium stabilized zirconia particles, a single meridonial crack developed in one of the particles, breaking it into two parts.« less

Rip currents and alongshore flows in single channels dredged in the surf zone

NASA Astrophysics Data System (ADS)

Moulton, Melissa; Elgar, Steve; Raubenheimer, Britt; Warner, John C.; Kumar, Nirnimesh

2017-05-01

To investigate the dynamics of flows near nonuniform bathymetry, single channels (on average 30 m wide and 1.5 m deep) were dredged across the surf zone at five different times, and the subsequent evolution of currents and morphology was observed for a range of wave and tidal conditions. In addition, circulation was simulated with the numerical modeling system COAWST, initialized with the observed incident waves and channel bathymetry, and with an extended set of wave conditions and channel geometries. The simulated flows are consistent with alongshore flows and rip-current circulation patterns observed in the surf zone. Near the offshore-directed flows that develop in the channel, the dominant terms in modeled momentum balances are wave-breaking accelerations, pressure gradients, advection, and the vortex force. The balances vary spatially, and are sensitive to wave conditions and the channel geometry. The observed and modeled maximum offshore-directed flow speeds are correlated with a parameter based on the alongshore gradient in breaking-wave-driven-setup across the nonuniform bathymetry (a function of wave height and angle, water depths in the channel and on the sandbar, and a breaking threshold) and the breaking-wave-driven alongshore flow speed. The offshore-directed flow speed increases with dissipation on the bar and reaches a maximum (when the surf zone is saturated) set by the vertical scale of the bathymetric variability.

Rip currents and alongshore flows in single channels dredged in the surf zone

USGS Publications Warehouse

Moulton, Melissa; Elgar, Steve; Raubenheimer, Britt; Warner, John C.; Kumar, Nirnimesh

2017-01-01

To investigate the dynamics of flows near nonuniform bathymetry, single channels (on average 30 m wide and 1.5 m deep) were dredged across the surf zone at five different times, and the subsequent evolution of currents and morphology was observed for a range of wave and tidal conditions. In addition, circulation was simulated with the numerical modeling system COAWST, initialized with the observed incident waves and channel bathymetry, and with an extended set of wave conditions and channel geometries. The simulated flows are consistent with alongshore flows and rip-current circulation patterns observed in the surf zone. Near the offshore-directed flows that develop in the channel, the dominant terms in modeled momentum balances are wave-breaking accelerations, pressure gradients, advection, and the vortex force. The balances vary spatially, and are sensitive to wave conditions and the channel geometry. The observed and modeled maximum offshore-directed flow speeds are correlated with a parameter based on the alongshore gradient in breaking-wave-driven-setup across the nonuniform bathymetry (a function of wave height and angle, water depths in the channel and on the sandbar, and a breaking threshold) and the breaking-wave-driven alongshore flow speed. The offshore-directed flow speed increases with dissipation on the bar and reaches a maximum (when the surf zone is saturated) set by the vertical scale of the bathymetric variability.

Application of the aberration ring test (ARTEMIS) to determine lens quality and predict its lithographic performance

NASA Astrophysics Data System (ADS)

Moers, Marco H. P.; van der Laan, Hans; Zellenrath, Mark; de Boeij, Wim; Beaudry, Neil A.; Cummings, Kevin D.; van Zwol, Adriaan; Brecht, Arthur; Willekers, Rob

2001-09-01

ARTEMISTM (Aberration Ring Test Exposed at Multiple Illumination Settings) is a technique to determine in-situ, full-field, low and high order lens aberrations. In this paper we are analyzing the ARTEMISTM data of PAS5500/750TM DUV Step & Scan systems and its use as a lithographic prediction tool. ARTEMISTM is capable of determining Zernike coefficients up to Z25 with a 3(sigma) reproducibility range from 1.5 to 4.5 nm depending on the aberration type. 3D electric field simulations, that take the extended geometry of the phase shift feature into account, have been used for an improved treatment of the extraction of the spherical Zernike coefficients. Knowledge of the extracted Zernike coefficients allows an accurate prediction of the lithographic performance of the scanner system. This ability is demonstrated for a two bar pattern and an isolation pattern. The RMS difference between the ARTEMISTM-based lithographic prediction and the lithographic measurement is 2.5 nm for the two bar pattern and 3 nm for the isolation pattern. The 3(sigma) reproducibility of the prediction for the two bar pattern is 2.5 nm and 1 nm for the isolation pattern. This is better than the reproducibility of the lithographic measurements themselves.

GaAs digital dynamic IC's for applications up to 10 GHz

NASA Astrophysics Data System (ADS)

Rocchi, M.; Gabillard, B.

1983-06-01

To evaluate the potentiality of GaAs MESFET's as transmitting gates, dynamic TT-bar flip-flops have been fabricated using a self-aligned planar process. The maximum operating frequency is 10.2 GHz, which is the best speed performance ever reported for a digital circuit. The performance of the transmitting gates within the circuits are discussed in detail. Speed improvement and topological simplification of fully static LSI subsystems are investigated.

Icing research tunnel rotating bar calibration measurement system

NASA Technical Reports Server (NTRS)

Gibson, Theresa L.; Dearmon, John M.

1993-01-01

In order to measure icing patterns across a test section of the Icing Research Tunnel, an automated rotating bar measurement system was developed at the NASA Lewis Research Center. In comparison with the previously used manual measurement system, this system provides a number of improvements: increased accuracy and repeatability, increased number of data points, reduced tunnel operating time, and improved documentation. The automated system uses a linear variable differential transformer (LVDT) to measure ice accretion. This instrument is driven along the bar by means of an intelligent stepper motor which also controls data recording. This paper describes the rotating bar calibration measurement system.

Transient dynamics of invasive competition: barred owls, spotted owls, habitat, and the demons of competition present.

PubMed

Dugger, Katie M; Anthony, Robert G; Andrews, Lawrence S

2011-10-01

The recent range expansion of Barred Owls (Strix varia) into the Pacific Northwest, where the species now co-occurs with the endemic Northern Spotted Owl (Strix occidentalis caurina), resulted in a unique opportunity to investigate potential competition between two congeneric, previously allopatric species. The primary criticism of early competition research was the use of current species' distribution patterns to infer past processes; however, the recent expansion of the Barred Owl and the ability to model the processes that result in site occupancy (i.e., colonization and extinction) allowed us to address the competitive process directly rather than inferring past processes through current patterns. The purpose of our study was to determine whether Barred Owls had any negative effects on occupancy dynamics of nesting territories by Northern Spotted Owls and how these effects were influenced by habitat characteristics of Spotted Owl territories. We used single-species, multi-season occupancy models and covariates quantifying Barred Owl detections and habitat characteristics to model extinction and colonization rates of Spotted Owl pairs in southern Oregon, USA. We observed a strong, negative association between Barred Owl detections and colonization rates and a strong positive effect of Barred Owl detections on extinction rates of Spotted Owls. We observed increased extinction rates in response to decreased amounts of old forest at the territory core and higher colonization rates when old-forest habitat was less fragmented. Annual site occupancy for pairs reflected the strong effects of Barred Owls on occupancy dynamics with much lower occupancy rates predicted for territories where Barred Owls were detected. The strong Barred Owl and habitat effects on occupancy dynamics of Spotted Owls provided evidence of interference competition between the species. These effects increase the importance of conserving large amounts of contiguous, old-forest habitat to maintain Northern Spotted Owls in the landscape.

Bars in dark-matter-dominated dwarf galaxy discs

NASA Astrophysics Data System (ADS)

Marasco, A.; Oman, K. A.; Navarro, J. F.; Frenk, C. S.; Oosterloo, T.

2018-05-01

We study the shape and kinematics of simulated dwarf galaxy discs in the APOSTLE suite of Λ cold dark matter (ΛCDM) cosmological hydrodynamical simulations. We find that a large fraction of these gas-rich, star-forming discs show weak bars in their stellar component, despite being dark-matter-dominated systems. The bar pattern shape and orientation reflect the ellipticity of the dark matter potential, and its rotation is locked to the slow figure rotation of the triaxial dark halo. The bar-like nature of the potential induces non-circular motions in the gas component, including strong bisymmetric flows that can be readily seen as m = 3 harmonic perturbations in the H I line-of-sight velocity fields. Similar bisymmetric flows are seen in many galaxies of The HI Nearby Galaxy Survey (THINGS) and Local Irregulars That Trace Luminosity Extremes THINGS (LITTLE THINGS), although on average their amplitudes are a factor of ˜2 weaker than in our simulated discs. Our results indicate that bar-like patterns may arise even when baryons are not dominant, and that they are common enough to warrant careful consideration when analysing the gas kinematics of dwarf galaxy discs.

Comparative stress distribution of implant-retained mandibular ball-supported and bar-supported overlay dentures: a finite element analysis.

PubMed

Vafaei, Fariborz; Khoshhal, Masoumeh; Bayat-Movahed, Saeed; Ahangary, Ahmad Hassan; Firooz, Farnaz; Izady, Alireza; Rakhshan, Vahid

2011-08-01

Implant-retained mandibular ball-supported and bar-supported overlay dentures are the two most common treatment options for the edentulous mandible. The superior option in terms of strain distribution should be determined. The three-dimensional model of mandible (based on computerized tomography scan) and its overlying implant-retained bar-supported and ball-supported overlay dentures were simulated using SolidWorks, NURBS, and ANSYS Workbench. Loads A (60 N) and B (60 N) were exerted, respectively, in protrusive and laterotrusive motions, on second molar mesial, first molar mesial, and first premolar. The strain distribution patterns were assessed on (1) implant tissue, (2) first implant-bone, and (3) second implant-bone interfaces. Protrusive: Strain was mostly detected in the apical of the fixtures and least in the cervical when bar design was used. On the nonworking side, however, strain was higher in the cervical and lower in the apical compared with the working side implant. Laterotrusive: The strain values were closely similar in the two designs. It seems that both designs are acceptable in terms of stress distribution, although a superior pattern is associated with the application of bar design in protrusive motion.

Development of a two-stage light gas gun to accelerate hydrogen pellets to high speeds for plasma fueling applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Combs, S.K.; Milora, S.L.; Foust, C.R.

1989-05-01

The development of a two-stage light gas gun to accelerate hydrogen isotope pellets to high speeds is under way at Oak Ridge National Laboratory. High velocities (>2 km/s) are desirable for plasma fueling applications, since the faster pellets can penetrate more deeply into large, hot plasmas and deposit atoms of fuel directly in a larger fraction of the plasma volume. In the initial configuration of the two-stage device, a 2.2-1 volume (less than or equal to55 bar) provides the gas to accelerate a 25.4-mm-diam piston in a 1-m-long pump tube; a burst disk or a fast valve initiates the accelerationmore » process in the first stage. As the piston travels the length of the pump tube, the downstream gas (initially at <1 bar) is compressed (to pressures up to 2600 bar) and thus is driven to high temperature (approx. =5000 K). This provides the driving force for acceleration of a 4-mm pellet in a 1-m-long gun barrel. In preliminary tests using helium as the driver in both stages, 35-mg plastic pellets have been accelerated to speeds as high as 4.0 km/s. Projectiles composed of hydrogen ice will have a mass in the range from 5 to 20 mg ( rhoapprox. =0.087, 0.20, and 0.32 g/cm/sup 3/ for frozen hydrogen isotopes). However, the use of sabots to encase and protect the cryogenic pellets from the high peak pressures will probably be required to realize speeds of approx. =3 km/s or greater. The experimental plan includes acceleration of hydrogen isotopes as soon as the gun geometry and operating parameters are optimized; theoretical models are being used to aid in this process. The hardware is being designed to accommodate repetitive operation, which is the objective of this research and is required for future applications.« less

Development of a two-stage light gas gun to accelerate hydrogen pellets to high speeds for plasma fueling applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Combs, S.K.; Milora, S.L.; Foust, C.R.

1988-01-01

The development of a two-stage light gas gun to accelerate hydrogen isotope pellets to high speeds is under way at Oak Ridge National Laboratory. High velocities (>2 km/s) are desirable for plasma fueling applications, since the faster pellets can penetrate more deeply into large, hot plasmas and deposit atoms of fuel directly in a larger fraction of the plasma volume. In the initial configuration of the two-stage device, a 2.2-l volume (/<=/55-bar) provides the gas to accelerate a 25.4-mm-diam piston in a 1-m-long pump tube; a burst disk or a fast valve initiates the acceleration process in the first stage.more » As the piston travels the length of the pump tube, the downstream gas (initially at <1 bar) is compressed (to pressures up to 2600 bar) and thus is driven to high temperature (approx.5000 K). This provides the driving force for acceleration of a 4-mm pellet in a 1-m-long gun barrel. In preliminary tests using helium as the driver in both stages, 35-mg plastic pellets have been accelerated to speeds as high as 3.8 km/s. Projectiles composed of hydrogen ice will have a mass in the range from 5 to 20 mg (/rho/ approx. 0.087, 0.20, and 0.32 g/cm/sup 3/ for frozen hydrogen isotopes). However, the use of sabots to encase and protect the cryogenic pellets from the high peak pressures will probably be required to realize speeds of approx.3 km/s or greater. The experimental plan includes acceleration of hydrogen isotopes as soon as the gun geometry and operating parameters are optimized; theoretical models are being used to aid in this process. The hardware is being designed to accommodate repetitive operation, which is the objective of this research and is required for future applications. 25 refs., 6 figs., 1 tab.« less

Common evolutionary trends underlie the four-bar linkage systems of sunfish and mantis shrimp.

PubMed

Hu, Yinan; Nelson-Maney, Nathan; Anderson, Philip S L

2017-05-01

Comparative biomechanics offers an opportunity to explore the evolution of disparate biological systems that share common underlying mechanics. Four-bar linkage modeling has been applied to various biological systems such as fish jaws and crustacean appendages to explore the relationship between biomechanics and evolutionary diversification. Mechanical sensitivity states that the functional output of a mechanical system will show differential sensitivity to changes in specific morphological components. We document similar patterns of mechanical sensitivity in two disparate four-bar systems from different phyla: the opercular four-bar system in centrarchid fishes and the raptorial appendage of stomatopods. We built dynamic linkage models of 19 centrarchid and 36 stomatopod species and used phylogenetic generalized least squares regression (PGLS) to compare evolutionary shifts in linkage morphology and mechanical outputs derived from the models. In both systems, the kinematics of the four-bar mechanism show significant evolutionary correlation with the output link, while travel distance of the output arm is correlated with the coupler link. This common evolutionary pattern seen in both fish and crustacean taxa is a potential consequence of the mechanical principles underlying four-bar systems. Our results illustrate the potential influence of physical principles on morphological evolution across biological systems with different structures, behaviors, and ecologies. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Partial entrainment of gravel bars during floods

USGS Publications Warehouse

Konrad, Christopher P.; Booth, Derek B.; Burges, Stephen J.; Montgomery, David R.

2002-01-01

Spatial patterns of bed material entrainment by floods were documented at seven gravel bars using arrays of metal washers (bed tags) placed in the streambed. The observed patterns were used to test a general stochastic model that bed material entrainment is a spatially independent, random process where the probability of entrainment is uniform over a gravel bar and a function of the peak dimensionless shear stress τ0* of the flood. The fraction of tags missing from a gravel bar during a flood, or partial entrainment, had an approximately normal distribution with respect to τ0* with a mean value (50% of the tags entrained) of 0.085 and standard deviation of 0.022 (root‐mean‐square error of 0.09). Variation in partial entrainment for a given τ0* demonstrated the effects of flow conditioning on bed strength, with lower values of partial entrainment after intermediate magnitude floods (0.065 < τ0*< 0.08) than after higher magnitude floods. Although the probability of bed material entrainment was approximately uniform over a gravel bar during individual floods and independent from flood to flood, regions of preferential stability and instability emerged at some bars over the course of a wet season. Deviations from spatially uniform and independent bed material entrainment were most pronounced for reaches with varied flow and in consecutive floods with small to intermediate magnitudes.

Dynamic High-temperature Testing of an Iridium Alloy in Compression at High-strain Rates: Dynamic High-temperature Testing

DOE PAGES

Song, B.; Nelson, K.; Lipinski, R.; ...

2014-08-21

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-strain -rate performance are needed for understanding high-speed impacts in severe environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain -rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. In our study, we analyzed the difficulties encountered in high-temperature Kolsky bar testing of thin iridium alloy specimens in compression. We made appropriate modifications using themore » current high-temperature Kolsky bar technique in order to obtain reliable compressive stress–strain response of an iridium alloy at high-strain rates (300–10 000 s -1) and temperatures (750 and 1030°C). The compressive stress–strain response of the iridium alloy showed significant sensitivity to both strain rate and temperature.« less

Patterns of anterior and posterior muscle chain interactions during high performance long-hang elements in gymnastics.

PubMed

von Laßberg, Christoph; Rapp, Walter; Krug, Jürgen

2014-06-01

In a prior study with high level gymnasts we could demonstrate that the neuromuscular activation pattern during the "whip-like" leg acceleration phases (LAP) in accelerating movement sequences on high bar, primarily runs in a consecutive succession from the bar (punctum fixum) to the legs (punctum mobile). The current study presents how the neuromuscular activation is represented during movement sequences that immediately follow the LAP by the antagonist muscle chain to generate an effective transfer of momentum for performing specific elements, based on the energy generated by the preceding LAP. Thirteen high level gymnasts were assessed by surface electromyography during high performance elements on high bar and parallel bars. The results show that the neuromuscular succession runs primarily from punctum mobile towards punctum fixum for generating the transfer of momentum. Additionally, further principles of neuromuscular interactions between the anterior and posterior muscle chain during such movement sequences are presented. The findings complement the understanding of neuromuscular activation patterns during rotational movements around fixed axes and will help to form the basis of more direct and better teaching methods regarding earlier optimization and facilitation of the motor learning process concerning fundamental movement requirements. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamic Testing of Laterally Confined Concrete

DTIC Science & Technology

1990-09-01

for Intermediate Confining pressure (Dashed Curve). 31 23. Example of Regression Fit by Equation (6) for Highest Pressure Group (Dashed Curve... pressure group , loaded by a moderate striker-bar impact speed of 420 in/sec. (10.7 m/s). The peak stress of 124 MPa (18 ksi) occurs at a strain of...survived at one end. This was for the highest speed impact in the lowest confining pressure group . Curves are given in the Appendix Figure A-15. The

A nonlinear dynamics approach for incorporating wind-speed patterns into wind-power project evaluation.

PubMed

Huffaker, Ray; Bittelli, Marco

2015-01-01

Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind-the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns.

Discovering shared segments on the migration route of the bar-headed goose by time-based plane-sweeping trajectory clustering

USGS Publications Warehouse

Luo, Ze; Baoping, Yan; Takekawa, John Y.; Prosser, Diann J.

2012-01-01

We propose a new method to help ornithologists and ecologists discover shared segments on the migratory pathway of the bar-headed geese by time-based plane-sweeping trajectory clustering. We present a density-based time parameterized line segment clustering algorithm, which extends traditional comparable clustering algorithms from temporal and spatial dimensions. We present a time-based plane-sweeping trajectory clustering algorithm to reveal the dynamic evolution of spatial-temporal object clusters and discover common motion patterns of bar-headed geese in the process of migration. Experiments are performed on GPS-based satellite telemetry data from bar-headed geese and results demonstrate our algorithms can correctly discover shared segments of the bar-headed geese migratory pathway. We also present findings on the migratory behavior of bar-headed geese determined from this new analytical approach.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Nelson, Kevin; Lipinski, Ronald J.

Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzedmore » the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s -1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.« less

The origin of the LMC stellar bar: clues from the SFH of the bar and inner disc

NASA Astrophysics Data System (ADS)

Monteagudo, L.; Gallart, C.; Monelli, M.; Bernard, E. J.; Stetson, P. B.

2018-01-01

We discuss the origin of the Large Magellanic Cloud (LMC) stellar bar by comparing the star formation histories (SFHs) obtained from deep colour-magnitude diagrams (CMDs) in the bar and in a number of fields in different directions within the inner disc. The CMDs, reaching the oldest main-sequence turn-offs in these very crowded fields, have been obtained with VIMOS on the Very Large Telescope in the service mode, under very good seeing conditions. We show that the SFHs of all fields share the same patterns, with consistent variations of the star formation rate as a function of time in all of them. We therefore conclude that no specific event of star formation can be identified with the formation of the LMC bar, which instead likely formed from a redistribution of disc material which occurred when the LMC disc became bar unstable, and shared a common SFH with the inner disc thereafter. The strong similarity between the SFH of the centre and edge of the bar rules out the expected significant spatial variations of the SFH across the bar.

Fluvial islands: First stage of development from nonmigrating (forced) bars and woody-vegetation interactions

NASA Astrophysics Data System (ADS)

Wintenberger, Coraline L.; Rodrigues, Stéphane; Bréhéret, Jean-Gabriel; Villar, Marc

2015-10-01

Fluvial islands can develop from the channel bed by interactions between pioneer trees and bars. Although vegetation recruitment and survival is possible on all bar types, it is easier for trees to survive on nonmigrating bars developed from a change in channel geometry or to the presence of a steady perturbation. This field study details the first stages of development of a vegetated mid-channel, nonmigrating (or forced) bar and its evolution toward an island form. Over six years, analysis of bed topographical changes, vegetation density and roughness, scour and fill depths, sediment grain size and architecture, and excess bed shear stress highlighted a specific signature of trees on topography and grain size segregation. Two depositional processes combining the formation of obstacle marks and upstream-shifting deposition of sediments led to the vertical accretion of the vegetated bar. During the first stage of the bar accretion, bedload sediment supply coming from surrounding channels during floods was identified as a key process modulated by the presence of woody vegetation and a deflection effect induced by the preexisting topography. Grain size segregation between vegetated and bare areas was also highlighted and interpreted as an important process affecting the development of surrounding channels and the degree of disconnection (and hence the speed of development) of a growing island. The heterogeneity of bedload supply can explain why sediment deposition and density of trees are not strictly related. A general conceptual model detailing the first stages of evolution from a bar to an established island is proposed for relatively large lowland rivers.

The Riemann problem for longitudinal motion in an elastic-plastic bar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trangenstein, J.A.; Pember, R.B.

In this paper the analytical solution to the Riemann problem for the Antman-Szymczak model of longitudinal motion in an elastic-plastic bar is constructed. The model involves two surfaces corresponding to plastic yield in tension and compression, and exhibits the appropriate limiting behavior for total compressions. The solution of the Riemann problem involves discontinuous changes in characteristic speeds due to transitions from elastic to plastic response. Illustrations are presented, in both state-space and self-similar coordinates, of the variety of possible solutions to the Riemann problem for possible use with numerical algorithms.

Search For Star Cluster Age Gradients Across Spiral Arms of Three LEGUS Disk Galaxies

NASA Astrophysics Data System (ADS)

Shabani, F.; Grebel, E. K.; Pasquali, A.; D'Onghia, E.; Gallagher, J. S.; Adamo, A.; Messa, M.; Elmegreen, B. G.; Dobbs, C.; Gouliermis, D. A.; Calzetti, D.; Grasha, K.; Elmegreen, D. M.; Cignoni, M.; Dale, D. A.; Aloisi, A.; Smith, L. J.; Tosi, M.; Thilker, D. A.; Lee, J. C.; Sabbi, E.; Kim, H.; Pellerin, A.

2018-05-01

One of the main theories for explaining the formation of spiral arms in galaxies is the stationary density wave theory. This theory predicts the existence of an age gradient across the arms. We use the stellar cluster catalogues of the galaxies NGC 1566, M51a, and NGC 628 from the Legacy Extragalactic UV Survey (LEGUS) program. In order to test for the possible existence of an age sequence across the spiral arms, we quantified the azimuthal offset between star clusters of different ages in our target galaxies. We found that NGC 1566, a grand-design spiral galaxy with bisymmetric arms and a strong bar, shows a significant age gradient across the spiral arms that appears to be consistent with the prediction of the stationary density wave theory. In contrast, M51a with its two well-defined spiral arms and a weaker bar does not show an age gradient across the arms. In addition, a comparison with non-LEGUS star cluster catalogues for M51a yields similar results. We believe that the spiral structure of M51a is not the result of a stationary density wave with a fixed pattern speed. Instead, tidal interactions could be the dominant mechanism for the formation of spiral arms. We also found no offset in the azimuthal distribution of star clusters with different ages across the weak spiral arms of NGC 628.

Seismic Behavior and Retrofit of Concrete Columns of Old R.C. Buildings Reinforced With Plain Bars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marefat, M. S.; Arani, K. Karbasi; Shirazi, S. M. Hassanzadeh

2008-07-08

Seismic rehabilitation of old buildings has been a major challenge in recent years. The first step in seismic rehabilitation is evaluation of the existing capacity and the seismic behaviour. For investigation of the seismic behaviour of RC members of a real old building in Iran which has been designed and constructed by European engineers in 1940, three half-scale column specimens reinforced with plain bars have been tested. The tests indicate significant differences between the responses of specimens reinforced by plain bars relative to those reinforced by deformed bars. A regular pattern of cracking and a relatively brittle behaviour was observedmore » while a relatively large residual strength appeared after sudden drop of initial strength and stiffness due to slip of longitudinal bars.« less

Evaluating diffraction based overlay metrology for double patterning technologies

NASA Astrophysics Data System (ADS)

Saravanan, Chandra Saru; Liu, Yongdong; Dasari, Prasad; Kritsun, Oleg; Volkman, Catherine; Acheta, Alden; La Fontaine, Bruno

2008-03-01

Demanding sub-45 nm node lithographic methodologies such as double patterning (DPT) pose significant challenges for overlay metrology. In this paper, we investigate scatterometry methods as an alternative approach to meet these stringent new metrology requirements. We used a spectroscopic diffraction-based overlay (DBO) measurement technique in which registration errors are extracted from specially designed diffraction targets for double patterning. The results of overlay measurements are compared to traditional bar-in-bar targets. A comparison between DBO measurements and CD-SEM measurements is done to show the correlation between the two approaches. We discuss the total measurement uncertainty (TMU) requirements for sub-45 nm nodes and compare TMU from the different overlay approaches.

A Nonlinear Dynamics Approach for Incorporating Wind-Speed Patterns into Wind-Power Project Evaluation

PubMed Central

Huffaker, Ray; Bittelli, Marco

2015-01-01

Wind-energy production may be expanded beyond regions with high-average wind speeds (such as the Midwest U.S.A.) to sites with lower-average speeds (such as the Southeast U.S.A.) by locating favorable regional matches between natural wind-speed and energy-demand patterns. A critical component of wind-power evaluation is to incorporate wind-speed dynamics reflecting documented diurnal and seasonal behavioral patterns. Conventional probabilistic approaches remove patterns from wind-speed data. These patterns must be restored synthetically before they can be matched with energy-demand patterns. How to accurately restore wind-speed patterns is a vexing problem spurring an expanding line of papers. We propose a paradigm shift in wind power evaluation that employs signal-detection and nonlinear-dynamics techniques to empirically diagnose whether synthetic pattern restoration can be avoided altogether. If the complex behavior of observed wind-speed records is due to nonlinear, low-dimensional, and deterministic system dynamics, then nonlinear dynamics techniques can reconstruct wind-speed dynamics from observed wind-speed data without recourse to conventional probabilistic approaches. In the first study of its kind, we test a nonlinear dynamics approach in an application to Sugarland Wind—the first utility-scale wind project proposed in Florida, USA. We find empirical evidence of a low-dimensional and nonlinear wind-speed attractor characterized by strong temporal patterns that match up well with regular daily and seasonal electricity demand patterns. PMID:25617767

Calculation of equivalent friction coefficient for castor seed by single screw press

NASA Astrophysics Data System (ADS)

Liu, R.; Xiao, Z.; Li, C.; Zhang, L.; Li, P.; Li, H.; Zhang, A.; Tang, S.; Sun, F.

2017-08-01

Based on the traction angle and transportation rate equation, castor beans were pressed by application of single screw under different cake diameter and different screw speed. The results showed that the greater the cake diameter and screw rotation speed, the greater the actual transmission rate was. The equivalent friction coefficient was defined and calculated as 0.4136, and the friction coefficients between press material and screw, bar cage were less than the equivalent friction coefficient value.

An idealised study for the long term evolution of crescentic bars

NASA Astrophysics Data System (ADS)

Chen, W. L.; Dodd, N.; Tiessen, M. C. H.; Calvete, D.

2018-01-01

An idealised study that identifies the mechanisms in the long term evolution of crescentic bar systems in nature is presented. Growth to finite amplitude (i.e., equilibration, sometimes referred to as saturation) and higher harmonic interaction are hypothesised to be the leading nonlinear effects in long-term evolution of these systems. These nonlinear effects are added to a linear stability model and used to predict crescentic bar development along a beach in Duck, North Carolina (USA) over a 2-month period. The equilibration prolongs the development of bed patterns, thus allowing the long term evolution. Higher harmonic interaction enables the amplitude to be transferred from longer to shorter lengthscales, which leads to the dominance of shorter lengthscales in latter post-storm stages, as observed at Duck. The comparison with observations indicates the importance of higher harmonic interaction in the development of nearshore crescentic bar systems in nature. Additionally, it is concluded that these nonlinear effects should be included in models simulating the development of different bed patterns, and that this points a way forward for long-term morphodynamical modelling in general.

Subsurface flow in lowland river gravel bars

NASA Astrophysics Data System (ADS)

Bray, E. N.; Dunne, T.

2017-09-01

Geomorphic and hydraulic processes, which form gravel bars in large lowland rivers, have distinctive characteristics that control the magnitude and spatial patterns of infiltration and exfiltration between rivers and their immediate subsurface environments. We present a bedform-infiltration relation together with a set of field measurements along two reaches of the San Joaquin River, CA to illustrate the conditions required for infiltration and exfiltration of flow between a stream and its undulating bed, and a numerical model to investigate the factors that affect paths and residence times of flow through barforms at different discharges. It is shown that asymmetry of bar morphology is a first-order control on the extent and location of infiltration, which would otherwise produce equal areas of infiltration and exfiltration under the assumption of sinusoidal bedforms. Hydraulic conductivity varies by orders of magnitude due to fine sediment accumulation and downstream coarsening related to the process of bar evolution. This systematic variability not only controls the magnitude of infiltration, but also the residence time of flow through the bed. The lowest hydraulic conductivity along the reach occurred where the difference between the topographic gradient and the water-surface gradient is at a maximum and thus where infiltration would be greatest into a homogeneous bar, indicating the importance of managing sand supply to maintain the ventilation and flow through salmon spawning riffles. Numerical simulations corroborate our interpretation that infiltration patterns and rates are controlled by distinctive features of bar morphology.

Evaluation of best practices in traffic operations and safety : phase I : flashing LED stop sign and optical speed bars.

DOT National Transportation Integrated Search

2007-01-01

In a previous extensive review of overseas literature, researchers identified 42 traffic operations and safety technologies and practices that were not currently deployed in Virginia. These were evaluated for their potential application in Virginia, ...

Complete and rapid reversal of the body color pattern in juveniles of the convict surgeonfish Acanthurus triostegus at Moorea Island (French Polynesia)

NASA Astrophysics Data System (ADS)

Besson, Marc; Salis, Pauline; Laudet, Vincent; Lecchini, David

2018-03-01

Color polymorphism is widespread in animals and can be associated with temporary adjustments to environmental variables (phenotypic plasticity). In teleost fishes, one of the most remarkable examples of color plasticity is background adaptation in flatfishes. However, such rapid and complete changes in body color and pattern remain relatively unreported in other species. The convict surgeonfish Acanthurus triostegus is a gregarious species whose body color pattern consists of black vertical bars on a whitish body. Here, we describe an entirely reverse body color pattern (white vertical bars on a blackish body) that we observed in some A. triostegus juveniles in a nursery area at Moorea Island, French Polynesia. In aquaria, we determined that change from one color pattern to the other is rapid, reversible, and corresponds to phenotypic plasticity associated with aggressive behavior.

A tool to estimate bar patterns and flow conditions in estuaries when limited data is available

NASA Astrophysics Data System (ADS)

Leuven, J.; Verhoeve, S.; Bruijns, A. J.; Selakovic, S.; van Dijk, W. M.; Kleinhans, M. G.

2017-12-01

The effects of human interventions, natural evolution of estuaries and rising sea-level on food security and flood safety are largely unknown. In addition, ecologists require quantified habitat area to study future evolution of estuaries, but they lack predictive capability of bathymetry and hydrodynamics. For example, crucial input required for ecological models are values of intertidal area, inundation time, peak flow velocities and salinity. While numerical models can reproduce these spatial patterns, their computational times are long and for each case a new model must be developed. Therefore, we developed a comprehensive set of relations that accurately predict the hydrodynamics and the patterns of channels and bars, using a combination of the empirical relations derived from approximately 50 estuaries and theory for bars and estuaries. The first step is to predict local tidal prisms, which is the tidal prism that flows through a given cross-section. Second, the channel geometry is predicted from tidal prism and hydraulic geometry relations. Subsequently, typical flow velocities can be estimated from the channel geometry and tidal prism. Then, an ideal estuary shape is fitted to the measured planform: the deviation from the ideal shape, which is defined as the excess width, gives a measure of the locations where tidal bars form and their summed width (Leuven et al., 2017). From excess width, typical hypsometries can be predicted per cross-section. In the last step, flow velocities are calculated for the full range of occurring depths and salinity is calculated based on the estuary shape. Here, we will present a prototype tool that predicts equilibrium bar patterns and typical flow conditions. The tool is easy to use because the only input required is the estuary outline and tidal amplitude. Therefore it can be used by policy makers and researchers from multiple disciplines, such as ecologists, geologists and hydrologists, for example for paleogeographic reconstructions.

Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

PubMed

Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

2015-01-01

A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

Experimetal study on the FRP-concrete bond behavior under repeated loadings

NASA Astrophysics Data System (ADS)

Lee, J.-Y.; Yi, C.-K.; Cheong, Y.-G.

2009-11-01

In this study, the effects of repeated loads on the FRP-concrete bond strength were investigated experimentally by direct pull out tests according to CSA S806-02. A conventional reinforcing steel bar and two types of glass-fiber-reinforced plastic (GFRP) bars were embedded in concrete and tested under four different loading patterns. The bond strength-slip curves of the bars were obtained and analyzed. The results showed that the maximum bond strengths under the repeated loads differed from those obtained under monotonic ones. In addition, noticeable differences in degradation of the bond strength with respect to the magnitude of slip were observed between the different bar types tested. On the basis of an image analysis of failure surfaces, they were attributed to the different bond failure mechanisms associated with the steel and GFRP bars.

Letting Your Students "Fly" in the Classroom.

ERIC Educational Resources Information Center

Adams, Thomas

1997-01-01

Students investigate the concept of motion by making simple paper airplanes and flying them in the classroom. Students are introduced to conversion factors to calculate various speeds. Additional activities include rounding decimal numbers, estimating, finding averages, making bar graphs, and solving problems. Offers ideas for extension such as…

Research Advances: Bio-Bar-Codes Speed DNA Detection; Treating Cystic Fibrosis from the Spice Rack; Salmonella versus Salsa

NASA Astrophysics Data System (ADS)

King, Angela G.

2004-10-01

This Report from Other Journals surveys articles of interest to chemists that have been recently published in other science journals. The articles selected specifically relate to the theme of National Chemistry Week 2004: health and wellness.

The Sidebar Computer Program, a seismic-shaking intensity meter: users' manual and software description

USGS Publications Warehouse

Evans, John R.

2003-01-01

The SideBar computer program provides a visual display of seismic shaking intensity as recorded at one specific seismograph. This software allows a user to tap into the seismic data recorded on that specific seismograph and to display the overall level of shaking at the single location where that seismograph resides (usually the same place the user is). From this shaking level, SideBar also estimates the potential for damage nearby. SideBar cannot tell you the “Richter magnitude” of the earthquake (see box), only how hard the ground shook locally and this estimate of how much damage is likely in the neighborhood. This combination of local effects is called the “seismic intensity”. SideBar runs on a standard desktop or laptop PC, and is intended for the media, schools, emergency responders, and any other group hosting a seismograph and who want to know immediately after an earthquake the levels of shaking measured by that instrument. These local values can be used to inform the public and help initiate appropriate local emergency response activities in the minutes between the earthquake and availability of the broader coverage provided by the USGS over the Web, notably by ShakeMap. For example, for instruments installed in schools, the level of shaking and likely damage at the school could immediately be Web broadcast and parents could quickly determine the likely safety of their children—their biggest postearthquake concern. Also, in the event of a Web outage, SideBar may be a continuing primary source of local emergency response information for some additional minutes. Specifically, SideBar interprets the peak level of acceleration (that is, the force of shaking, as a percentage of the force of gravity) as well as the peak velocity, or highest speed, at which the ground moves. Using these two basic measurements, SideBar computes what is called Instrumental Intensity—a close approximation of the Modified Mercalli Intensity scale, or “MMI” (using the Wald et al., 1999a, relationships between acceleration, velocity, and shaking intensity). Intensity is a measure of local shaking strength and the potential for damage—of how bad the earthquake effects were locally. The intensity level is what SideBar displays most prominently on the PC monitor. Intensity is shown as a large, colored bar that gets taller and changes color up a rainbow from blues toward reds as the shaking level increases. As opposed to earthquake magnitudes, which are reported as decimal values (like “7.6”), intensity is traditionally given as a Roman numeral, with “I” to “X+” assigned to levels of potential damage and perceived shaking strength. For good measure, SideBar shows the actual values of the force of shaking (peak ground acceleration as a percentage of gravity) and the speed of ground motion (peak ground velocity in inches per second, by default, or in centimeters per second, if you wish), both these values as decimal numbers. SideBar also remembers the most recent earthquakes (for up to one week), and can store as many of these previous earthquakes as the user allows (and as the user’s PC has room for)—typically thousands. SideBar also remembers forever the three largest earthquakes it has seen and all earthquakes over intensity IV so that one never loses particularly important events.

Simultaneous X-ray diffraction and phase-contrast imaging for investigating material deformation mechanisms during high-rate loading

DOE PAGES

Hudspeth, M.; Sun, T.; Parab, N.; ...

2015-01-01

Using a high-speed camera and an intensified charge-coupled device (ICCD), a simultaneous X-ray imaging and diffraction technique has been developed for studying dynamic material behaviors during high-rate tensile loading. A Kolsky tension bar has been used to pull samples at 1000 s –1and 5000 s –1strain-rates for super-elastic equiatomic NiTi and 1100-O series aluminium, respectively. By altering the ICCD gating time, temporal resolutions of 100 ps and 3.37 µs have been achieved in capturing the diffraction patterns of interest, thus equating to single-pulse and 22-pulse X-ray exposure. Furthermore, the sample through-thickness deformation process has been simultaneously imagedviaphase-contrast imaging. It ismore » also shown that adequate signal-to-noise ratios are achieved for the detected white-beam diffraction patterns, thereby allowing sufficient information to perform quantitative data analysis diffractionviain-house software ( WBXRD_GUI). Finally, of current interest is the ability to evaluate crystald-spacing, texture evolution and material phase transitions, all of which will be established from experiments performed at the aforementioned elevated strain-rates.« less

Imprint lithography template technology for bit patterned media (BPM)

NASA Astrophysics Data System (ADS)

Lille, J.; Patel, K.; Ruiz, R.; Wu, T.-W.; Gao, H.; Wan, Lei; Zeltzer, G.; Dobisz, E.; Albrecht, T. R.

2011-11-01

Bit patterned media (BPM) for magnetic recording has emerged as a promising technology to deliver thermally stable magnetic storage at densities beyond 1Tb/in2. Insertion of BPM into hard disk drives will require the introduction of nanoimprint lithography and other nanofabrication processes for the first time. In this work, we focus on nanoimprint and nanofabrication challenges that are being overcome in order to produce patterned media. Patterned media has created the need for new tools and processes, such as an advanced rotary e-beam lithography tool and block copolymer integration. The integration of block copolymer is through the use of a chemical contrast pattern on the substrate which guides the alignment of di-block copolymers. Most of the work on directed self assembly for patterned media applications has, until recently, concentrated on the formation of circular dot patterns in a hexagonal close packed lattice. However, interactions between the read head and media favor a bit aspect ratio (BAR) greater than one. This design constraint has motivated new approaches for using self-assembly to create suitable high-BAR master patterns and has implications for template fabrication.

A calibration loop to test hot-wire response under supercritical conditions

NASA Astrophysics Data System (ADS)

Radulović, Ivana; Vukoslavčević, P. V.; Wallace, J. M.

2004-11-01

A calibration facility to test the response of hot-wires in CO2 flow under supercritical conditions has been designed and constructed. It is capable of inducing variable speeds at different temperatures and pressures in the ranges of 0.15 - 2 m/s, 15 - 70 deg. C and 1 - 100 bar. The facility is designed as a closed loop with a test section, pump, electrical heater, DC motor and different regulating and measuring devices. The test section is a small tunnel, with a diffuser, honeycomb, screens and a nozzle to provide a uniform flow with a low turbulence level. The speed variation is created by a sealed, magnetic driven gear pump, with a variable rpm DC motor. Using the electrical heater and regulating the amount of CO2 in the facility, the desired temperature and pressure can be reached. The dimensions of the instalation are minimized to reduce the heat, pump power required, and CO2 consumption and to optimize safety. Preliminary testing of a single hot-wire velocity sensor at constant pressure (80 bar) and variable speed and temperature will be briefly described. The hot-wire probes calibrated in this loop will be used to measure turbulence properties in supercritical CO2 in support of improved designs of nuclear reactors to be cooled by supercritical fluids.

Training for Power and Speed: Effects of Increasing or Decreasing Jump Squat Velocity in Elite Young Soccer Players.

PubMed

Loturco, Irineu; Nakamura, Fabio Y; Kobal, Ronaldo; Gil, Saulo; Abad, César C Cal; Cuniyochi, Rogério; Pereira, Lucas A; Roschel, Hamilton

2015-10-01

The aim of this study was to test the effects of 2 different velocity-oriented power training regimens by either increasing or decreasing the jump squat velocity during jump training sessions applied 3 times a week for 6 weeks in soccer players. Twenty-four elite under-20 soccer players were randomly assigned to an increased bar velocity group (IVG) or a reduced bar velocity group (RVG). Athletes had their countermovement jump heights, mean propulsive velocities (MPVs) in jump squat, leg press maximum dynamic strength (1 repetition maximum [RM]), 20-m sprint times, and zig-zag change of direction (COD) abilities assessed before and after the intervention. Performance in all tests improved after training in both groups. However, greater gains in 1RM and MPV using 50-90% of body mass (BM) were noted for the RVG. The IVG demonstrated greater improvements in speed at 5, 10, and 20 m and MPV with no additional external load and with 40% BM. Both groups improved similarly in countermovement jumps and COD. To conclude, both velocity-oriented power training regimens were effective in eliciting neuromechanical adaptations, leading to better strength/power/speed performances, and the choice as to the most suitable method should be tailored according to players' needs/deficiencies.

Molecularly imprinted polymers based stir bar sorptive extraction for determination of cefaclor and cefalexin in environmental water.

PubMed

Peng, Jun; Liu, Donghao; Shi, Tian; Tian, Huairu; Hui, Xuanhong; He, Hua

2017-07-01

Although stir bar sportive extraction was thought to be a highly efficiency and simple pretreatment approach, its wide application was limited by low selectivity, short service life, and relatively high cost. In order to improve the performance of the stir bar, molecular imprinted polymers and magnetic carbon nanotubes were combined in the present study. In addition, two monomers were utilized to intensify the selectivity of molecularly imprinted polymers. Fourier transform infrared spectroscopy, scanning electron microscopy, and selectivity experiments showed that the molecularly imprinted polymeric stir bar was successfully prepared. Then micro-extraction based on the obtained stir bar was coupled with HPLC for determination of trace cefaclor and cefalexin in environmental water. This approach had the advantages of stir bar sportive extraction, high selectivity of molecular imprinted polymers, and high sorption efficiency of carbon nanotubes. To utilize this pretreatment approach, pH, extraction time, stirring speed, elution solvent, and elution time were optimized. The LOD and LOQ of cefaclor were found to be 3.5 ng · mL -1 and 12.0 ng · mL -1 , respectively; the LOD and LOQ of cefalexin were found to be 3.0 ng · mL -1 and 10.0 ng · mL -1 , respectively. The recoveries of cefaclor and cefalexin were 86.5 ~ 98.6%. The within-run precision and between-run precision were acceptable (relative standard deviation <7%). Even when utilized in more than 14 cycles, the performance of the stir bar did not decrease dramatically. This demonstrated that the molecularly imprinted polymeric stir bar based micro-extraction was a convenient, efficient, low-cost, and a specific method for enrichment of cefaclor and cefalexin in environmental samples.

Nurses' attitudes toward the use of the bar-coding medication administration system.

PubMed

Marini, Sana Daya; Hasman, Arie; Huijer, Huda Abu-Saad; Dimassi, Hani

2010-01-01

This study determines nurses' attitudes toward bar-coding medication administration system use. Some of the factors underlying the successful use of bar-coding medication administration systems that are viewed as a connotative indicator of users' attitudes were used to gather data that describe the attitudinal basis for system adoption and use decisions in terms of subjective satisfaction. Only 67 nurses in the United States had the chance to respond to the e-questionnaire posted on the CARING list server for the months of June and July 2007. Participants rated their satisfaction with bar-coding medication administration system use based on system functionality, usability, and its positive/negative impact on the nursing practice. Results showed, to some extent, positive attitude, but the image profile draws attention to nurses' concerns for improving certain system characteristics. The high bar-coding medication administration system skills revealed a more negative perception of the system by the nursing staff. The reasons underlying dissatisfaction with bar-coding medication administration use by skillful users are an important source of knowledge that can be helpful for system development as well as system deployment. As a result, strengthening bar-coding medication administration system usability by magnifying its ability to eliminate medication errors and the contributing factors, maximizing system functionality by ascertaining its power as an extra eye in the medication administration process, and impacting the clinical nursing practice positively by being helpful to nurses, speeding up the medication administration process, and being user-friendly can offer a congenial settings for establishing positive attitude toward system use, which in turn leads to successful bar-coding medication administration system use.

Unit-bar migration and bar-trough deposition: impacts on hydraulic conductivity and grain size heterogeneity in a sandy streambed

NASA Astrophysics Data System (ADS)

Korus, Jesse T.; Gilmore, Troy E.; Waszgis, Michele M.; Mittelstet, Aaron R.

2018-03-01

The hydrologic function of riverbeds is greatly dependent upon the spatiotemporal distribution of hydraulic conductivity and grain size. Vertical hydraulic conductivity ( K v) is highly variable in space and time, and controls the rate of stream-aquifer interaction. Links between sedimentary processes, deposits, and K v heterogeneity have not been well established from field studies. Unit bars are building blocks of fluvial deposits and are key to understanding controls on heterogeneity. This study links unit bar migration to K v and grain size variability in a sand-dominated, low-sinuosity stream in Nebraska (USA) during a single 10-day hydrologic event. An incipient bar formed parallel to the thalweg and was highly permeable and homogenous. During high flow, this bar was submerged under 10-20 cm of water and migrated 100 m downstream and toward the channel margin, where it became markedly heterogeneous. Low- K v zones formed in the subsequent heterogeneous bar downstream of the original 15-40-cm-thick bar front and past abandoned bridge pilings. These low- K v zones correspond to a discontinuous 1-cm layer of fine sand and silt deposited in the bar trough. Findings show that K v heterogeneity relates chiefly to the deposition of suspended materials in low-velocity zones downstream of the bar and obstructions, and to their subsequent burial by migration of the bar during high flow. Deposition of the unit bar itself, although it emplaced the vast majority of the sediment volume, was secondary to bar-trough deposition as a control on the overall pattern of heterogeneity.

Are some gestalt principles deployed more readily than others during early development? The case of lightness versus form similarity.

PubMed

Quinn, Paul C; Bhatt, Ramesh S

2006-10-01

Four experiments investigated how readily infants achieve perceptual organization by lightness and form similarity. Infants were (a) familiarized with elements that could be organized into rows or columns on the basis of lightness or form similarity and tested with vertical versus horizontal bars depicting the familiar versus novel organization or (b) familiarized with bars and tested with elements. For lightness similarity, generalization occurred in both tasks; however, for form similarity, generalization occurred only in the elements --> bars task. The findings indicate that lightness similarity is more readily deployed than form similarity and are discussed in the context of (a) whether the difference reflects speed of application or experience-based learning, (b) evidence from visual agnosic patients and the time course of application of the principles in healthy adults, and (c) development of dorsal and ventral visual processing streams. Copyright 2006 APA.

Introducing a novel gravitation-based high-velocity compaction analysis method for pharmaceutical powders.

PubMed

Tanner, Timo; Antikainen, Osmo; Ehlers, Henrik; Yliruusi, Jouko

2017-06-30

With modern tableting machines large amounts of tablets are produced with high output. Consequently, methods to examine powder compression in a high-velocity setting are in demand. In the present study, a novel gravitation-based method was developed to examine powder compression. A steel bar is dropped on a punch to compress microcrystalline cellulose and starch samples inside the die. The distance of the bar is being read by a high-accuracy laser displacement sensor which provides a reliable distance-time plot for the bar movement. In-die height and density of the compact can be seen directly from this data, which can be examined further to obtain information on velocity, acceleration and energy distribution during compression. The energy consumed in compact formation could also be seen. Despite the high vertical compression speed, the method was proven to be cost-efficient, accurate and reproducible. Copyright © 2017 Elsevier B.V. All rights reserved.

Steady-state pattern electroretinogram and short-duration transient visual evoked potentials in glaucomatous and healthy eyes.

PubMed

Amarasekera, Dilru C; Resende, Arthur F; Waisbourd, Michael; Puri, Sanjeev; Moster, Marlene R; Hark, Lisa A; Katz, L Jay; Fudemberg, Scott J; Mantravadi, Anand V

2018-01-01

This study evaluates two rapid electrophysiological glaucoma diagnostic tests that may add a functional perspective to glaucoma diagnosis. This study aimed to determine the ability of two office-based electrophysiological diagnostic tests, steady-state pattern electroretinogram and short-duration transient visual evoked potentials, to discern between glaucomatous and healthy eyes. This is a cross-sectional study in a hospital setting. Forty-one patients with glaucoma and 41 healthy volunteers participated in the study. Steady-state pattern electroretinogram and short-duration transient visual evoked potential testing was conducted in glaucomatous and healthy eyes. A 64-bar-size stimulus with both a low-contrast and high-contrast setting was used to compare steady-state pattern electroretinogram parameters in both groups. A low-contrast and high-contrast checkerboard stimulus was used to measure short-duration transient visual evoked potential parameters in both groups. Steady-state pattern electroretinogram parameters compared were MagnitudeD, MagnitudeD/Magnitude ratio, and the signal-to-noise ratio. Short-duration transient visual evoked potential parameters compared were amplitude and latency. MagnitudeD was significantly lower in glaucoma patients when using a low-contrast (P = 0.001) and high-contrast (P < 0.001) 64-bar-size steady-state pattern electroretinogram stimulus. MagnitudeD/Magnitude ratio and SNR were significantly lower in the glaucoma group when using a high-contrast 64-bar-size stimulus (P < 0.001 and P = 0.010, respectively). Short-duration transient visual evoked potential amplitude and latency were not significantly different between the two groups. Steady-state pattern electroretinogram was effectively able to discern between glaucomatous and healthy eyes. Steady-state pattern electroretinogram may thus have a role as a clinically useful electrophysiological diagnostic tool. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Shear wave speed recovery using moving interference patterns obtained in sonoelastography experiments.

PubMed

McLaughlin, Joyce; Renzi, Daniel; Parker, Kevin; Wu, Zhe

2007-04-01

Two new experiments were created to characterize the elasticity of soft tissue using sonoelastography. In both experiments the spectral variance image displayed on a GE LOGIC 700 ultrasound machine shows a moving interference pattern that travels at a very small fraction of the shear wave speed. The goal of this paper is to devise and test algorithms to calculate the speed of the moving interference pattern using the arrival times of these same patterns. A geometric optics expansion is used to obtain Eikonal equations relating the moving interference pattern arrival times to the moving interference pattern speed and then to the shear wave speed. A cross-correlation procedure is employed to find the arrival times; and an inverse Eikonal solver called the level curve method computes the speed of the interference pattern. The algorithm is tested on data from a phantom experiment performed at the University of Rochester Center for Biomedical Ultrasound.

Novel combined stir bar sorptive extraction coupled with ultrasonic assisted extraction for the determination of brominated flame retardants in environmental samples using high performance liquid chromatography.

PubMed

Yu, Chunhe; Hu, Bin

2007-08-10

A combined stir bar coated with poly (dimethysiloxane)-beta-cyclodextrin (PDMS-beta-CD) on single side has been prepared for the first time by sol-gel method and was coupled with ultrasonic assisted extraction (UAE) for the determination of some brominated flame-retardant compounds (BFRs) in soil and dust samples by high performance liquid chromatography (HPLC). Four different kinds of coatings including PDMS-beta-CD, PDMS, carbowax (CW)-PDMS-poly (vinyl alcohol) (PVA) and PDMS-PVA were evaluated for stir bar sorptive extraction of BFRs by orthogonal experiment design. The experimental results reveal that the PDMS-beta-CD combined stir bar exhibited the best extraction efficiency for the target analytes. The reproducibility for the preparation of PDMS-beta-CD combined stir bar ranged from 1.3% to 15.7% in one batch, and 7.2% to 15.1% among batches. Extraction time, desorption solvent, concentration of methanol and NaCl in the matrix, pH, temperature and stirring speed were optimized. The combined stir bar can avoid direct friction of the coating with the bottom of the vessel, and could be used for more than 100 times. Linearity (>0.993), repeatability (<10.5%), reproducibility (<16.5%), recovery (56-118%) and detection limits (2.9-4.2 microg L(-1)) were proper to determine the seven BFRs. The developed method was applied to the determination of BFRs in soil and dust with satisfactory results.

The Effect of Multiple Firings on the Shear Bond Strength of Porcelain to a New Millable Alloy and a Conventional Casting Alloy

PubMed Central

Farzin, Mitra; Giti, Rashin; Asalforush-Rezaiye, Amin

2018-01-01

This study compared the effect of multiple firings on the shear bond strength (SBS) of porcelain to the new millable alloy (Ceramill Sintron) and a conventional casting alloy (4-all). Thirty-six cylindrical cores (6.8 × 9 mm) were made of millable and castable alloy through CAD/CAM and casting techniques, respectively (n = 18). In the center of each bar, a 4 × 4 × 2-mm shot of porcelain was fused. Having divided each group into 3 subgroups based on the number of firing cycles (3, 5, 7), the specimens were fixed in a universal testing machine and underwent a shear force test (1.5 mm/min crosshead speed) until fractured. Then the SBS values (MPa) were calculated, and the failure patterns were microscopically characterized as adhesive, cohesive, or mixed. Two-way ANOVA statistical test revealed that the number of porcelain firings had no significant effect on the SBS of any of the metal groups (p = 0.1); however, it was statistically higher in the millable group than the castable group (p < 0.05). Moreover, detecting the mixed failure pattern in all the specimens implied that the multiple firings had no significant effect on the failure pattern. The multiple porcelain firings had no significant effect on the SBS of porcelain to neither the millable nor castable alloys. PMID:29565827

Analysis of Power Generating Speed Bumps Made of Concrete Foam Composite

NASA Astrophysics Data System (ADS)

Syam, B.; Muttaqin, M.; Hastrino, D.; Sebayang, A.; Basuki, W. S.; Sabri, M.; Abda, S.

2017-03-01

This paper discusses the analysis of speed bump made of concrete foam composite which is used to generate electrical power. Speed bumps are designed to decelerate the speed of vehicles before passing through toll gates, public areas, or any other safety purposes. In Indonesia a speed bump should be designed in the accordance with KM Menhub 3 year 1994. In this research, the speed bump was manufactured with dimensions and geometry comply to the regulation mentioned above. Concrete foam composite speed bumps were used due to its light weight and relatively strong to receive vertical forces from the tyres of vehicles passing over the bumps. The reinforcement materials are processed from empty fruit bunch of oil palm. The materials were subjected to various tests to obtain its physical and mechanical properties. To analyze the structure stability of the speed bumps some models were analyzed using a FEM-based numerical softwares. It was obtained that the speed bumps coupled with polymeric composite bar (3 inches in diameter) are significantly reduce the radial stresses. In addition, the speed bumps equipped with polymeric composite casing or steel casing are also suitable for use as part of system components in producing electrical energy.

Developmental Changes is Expression of Beta-Adrenergic Receptors in Cultures of C2C12 Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, K. Y.; Vaughn, J. R.

2000-01-01

beta-Adrenergic receptor (bAR) agonists have been reported to modulate growth in several mammalian and avian species, and bAR agonists presumably exert their physiological action on skeletal muscle cells through this receptor. Because of the importance of bAR regulation on muscle protein metabolism in muscle cells, the objectives of this study were to determine the developmental expression pattern of the bAR population in C2C12 skeletal muscle cells, and to analyze changes in both the quantity and isoform expression of the major muscle protein, myosin. The number of bAR in mononucleated C2C12 cells was approximately 8,000 bAR per cell, which is comparable with the population reported in several other nonmuscle cell types. However, the bar population increased after myoblast fusion to greater than 50,000 bAR per muscle cell equivalent. The reasons for this apparent over-expression of bAR in C2C12 cells is not known. The quantity of myosin also increased after C2C12 myoblast fusion, but the quantity of myosin was less than that reported in primary muscle cell cultures. Finally, at least five different isoforms of myosin heavy chain could be resolved in C2C12 cells, and three of these exhibited either increased or decreased developmental regulation relative to the others. Thus, C2C12 myoblasts undergo developmental regulation of bAR population and myosin heavy chain isoform expression.

Novel Arch Bar Fabricated With a Computer-Aided Design and Three-Dimensional Printing: A Feasibility Study.

PubMed

He, Wei; Sun, Yuchun; Tian, Kaiyue; Xie, Xiaoyan; Wang, Xiaoxia; Li, Zili

2015-11-01

The aim of the present study was to evaluate the feasibility of the design and fabrication of a novel arch bar using 3-dimensional printing. Furthermore, the study assessed its use in a preliminary clinical study of intermaxillary fixation. Seven patients who met the inclusion criteria were enrolled in the present study. Plaster dental casts were created of each patient and scanned using cone-beam computed tomography to obtain digital casts. Computer-aided design software was then used to complete the virtual building of the arch bars, which were manufactured using 3-dimensional printing and a cobalt-chrome alloy. The clinical results were observed after the arch bars were fixed to the dentition with steel wires. The arch bar contacted the dentition with a "surface-to-surface" pattern. The utility of these novel arch bars was verified by successfully fitting them to the dental arches of the patients. All the patients achieved their desired occlusion. The results of the present study have illustrated that this digital method is feasible for constructing a novel arch bar, showing promise for clinical use. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Fuel Combustion Laboratory | Transportation Research | NREL

Science.gov Websites

detection of compounds at sub-parts per billion by volume levels. A high-performance liquid chromatograph ) platform; a high-pressure (1,200- bar) direct-injection system to minimize spray physics effects; and an combustion chamber. A high-speed pressure transducer measures chamber pressure to detect fuel ignition. Air

Bayesian Asymmetric Regression as a Means to Estimate and Evaluate Oral Reading Fluency Slopes

ERIC Educational Resources Information Center

Solomon, Benjamin G.; Forsberg, Ole J.

2017-01-01

Bayesian techniques have become increasingly present in the social sciences, fueled by advances in computer speed and the development of user-friendly software. In this paper, we forward the use of Bayesian Asymmetric Regression (BAR) to monitor intervention responsiveness when using Curriculum-Based Measurement (CBM) to assess oral reading…

"MAPHICS", its development and influence on the future of Science.

NASA Astrophysics Data System (ADS)

Castellano, Doc

2001-11-01

On the fifth 'anniversary' of his conferences with Einstein, the Author reviewed the State of the Art of Mathematical Physics. During this review, 1960, the Author formulated an Omega Science. Namely, combining the Philosophy of Mathematics with the Philosophy of Physics into ONE Philosophy, "MAPHICS". "MA from MAthematics and PH--ICS" from Physics; "MAPHICS" (TM). The PhD co. views Science in general, and Mathematical Physics in particular, from a Historic-Philosophical viewpoint. Thus, it remained anonymous and 'in the background' as publicly known Mathematicians and Physicists, with their great reservoir of rhetoric expertise in said Fields; gradually presented and refined the essence of what the Author calls "Spirito Mathematics". A Philosophical concept that now appears to be publicly developing, with the utilization of some its speed and resolution power. The Author will give at least three examples of its speed and resolution power. One being the partial differential equation in the development of Wave Mechanics & Quantum Mechanics. Namely, [(-ih bar(squared)/2m)(2nd Part.Der. psi/ respect to x)] + V psi = ih bar -(Part.Der. psi/respect to t).

High Strain Rate Testing of Rocks using a Split-Hopkinson-Pressure Bar

NASA Astrophysics Data System (ADS)

Zwiessler, Ruprecht; Kenkmann, Thomas; Poelchau, Michael; Nau, Siegfried; Hess, Sebastian

2016-04-01

Dynamic mechanical testing of rocks is important to define the onset of rate dependency of brittle failure. The strain rate dependency occurs through the propagation velocity limit (Rayleigh wave speed) of cracks and their reduced ability to coalesce, which, in turn, significantly increases the strength of the rock. We use a newly developed pressurized air driven Split-Hopkinson-Pressure Bar (SHPB), that is specifically designed for the investigation of high strain rate testing of rocks, consisting of several 10 to 50 cm long strikers and bar components of 50 mm in diameter and 2.5 meters in length each. The whole set up, composed of striker, incident- and transmission bar is available in aluminum, titanium and maraging steel to minimize the acoustic impedance contrast, determined by the change of density and speed of sound, to the specific rock of investigation. Dynamic mechanical parameters are obtained in compression as well as in spallation configuration, covering a wide spectrum from intermediate to high strain rates (100-103 s-1). In SHPB experiments [1] one-dimensional longitudinal compressive pulses of diverse shapes and lengths - formed with pulse shapers - are used to generate a variety of loading histories under 1D states of stress in cylindrical rock samples, in order to measure the respective stress-strain response at specific strain rates. Subsequent microstructural analysis of the deformed samples is aimed at quantification fracture orientation, fracture pattern, fracture density, and fracture surface properties as a function of the loading rate. Linking mechanical and microstructural data to natural dynamic deformation processes has relevance for the understanding of earthquakes, landslides, impacts, and has several rock engineering applications. For instance, experiments on dynamic fragmentation help to unravel super-shear rupture events that pervasively pulverize rocks up to several hundred meters from the fault core [2, 3, 4]. The dynamic, strain rate dependent behavior with strongly increasing strength and changing fracturing process has not been consequently considered in modeling of geo-hazards such as earthquakes, rock falls, landslides or even meteorite impacts [5]. Incorporation of dynamic material data therefore will contribute to improvements of forecast models and the understanding of fast geodynamic processes. References [1] Zhang, Q. B. & Zhao, J. (2013). A Review of Dynamic Experimental Techniques and Mechanical Behaviour of Rock Materials. Rock Mech Rock Eng. DOI 10.1007/s00603-013-0463-y [2] Doan, M. L., & Gary, G. (2009). Rock pulverization at high strain rate near the San Andreas fault. Nature Geosci., 2, 709-712. [3] Reches, Z. E., & Dewers, T. A. (2005). Gouge formation by dynamic pulverization during earthquake rupture. Earth Planet. Sci. Lett., 235, 361-374. [4] Fondriest, M., Aretusini, S., Di Toro, G., & Smith, S. A. (2015). Fracturing and rock pulverization along an exhumed seismogenic fault zone in dolostones: The Foiana Fault Zone (Southern Alps, Italy). Tectonophys.654, 56-74. [5] Kenkmann, T., Poelchau, M. H., & Wulf, G. (2014). Structural Geology of impact craters. J. .Struct. Geol., 62, 156-182.

J.J. O'Keefe's: A Participant-Observation Study of Teachers in a Bar on Friday Afternoon.

ERIC Educational Resources Information Center

Mehlenbacher, Sandra; Mehlenbacher, Earl

This research was undertaken with the idea that it may be possible to learn about teachers' work lives through the investigation of teacher behavior and attitudes in an out-of-work setting. Group and individual behavior of teachers who habitually gathered at the same bar on Friday afternoons was observed in order to examine patterns of interaction…

Morphology and spacing of river meander scrolls

NASA Astrophysics Data System (ADS)

Strick, Robert J. P.; Ashworth, Philip J.; Awcock, Graeme; Lewin, John

2018-06-01

Many of the world's alluvial rivers are characterised by single or multiple channels that are often sinuous and that migrate to produce a mosaicked floodplain landscape of truncated scroll (or point) bars. Surprisingly little is known about the morphology and geometry of scroll bars despite increasing interest from hydrocarbon geoscientists working with ancient large meandering river deposits. This paper uses remote sensing imagery, LiDAR data-sets of meandering scroll bar topography, and global coverage elevation data to quantify scroll bar geometry, anatomy, relief, and spacing. The analysis focuses on preserved scroll bars in the Mississippi River (USA) floodplain but also compares attributes to 19 rivers of different scale and depositional environments from around the world. Analysis of 10 large scroll bars (median area = 25 km2) on the Mississippi shows that the point bar deposits can be categorised into three different geomorphological units of increasing scale: individual 'scrolls', 'depositional packages', and 'point bar complexes'. Scroll heights and curvatures are greatest near the modern channel and at the terminating boundaries of different depositional packages, confirming the importance of the formative main channel on subsequent scroll bar relief and shape. Fourier analysis shows a periodic variation in signal (scroll bar height) with an average period (spacing) of 167 m (range 150-190 m) for the Mississippi point bars. For other rivers, a strong relationship exists between the period of scroll bars and the adjacent primary channel width for a range of rivers from 55 to 2042 mis 50% of the main channel width. The strength of this correlation over nearly two orders of magnitude of channel size indicates a scale independence of scroll bar spacing and suggests a strong link between channel migration and scroll bar construction with apparent regularities despite different flow regimes. This investigation of meandering river dynamics and floodplain patterns shows that it is possible to develop a suite of metrics that describe scroll bar morphology and geometry that can be valuable to geoscientists predicting the heterogeneity of subsurface meandering deposits.

Knowledge Representation of the Melody and Rhythm in Koto Songs

NASA Astrophysics Data System (ADS)

Deguchi, Sachiko; Shirai, Katsuhiko

This paper describes the knowledge representation of the melody and rhythm in koto songs based on the structure of the domain: the scale, melisma (the melody in a syllable), and bar. We have encoded koto scores and extracted 2,3,4-note melodic patterns sequentially from the voice part of koto scores. The 2,3,4-note patterns used in the melisma are limited and the percentages of top patterns are high. The 3,4-note melodic patterns are examined at each scale degree. These patterns are more restricted than the patterns that are possible under the constraint of the scale. These typical patterns on the scale represent the knowledge of koto players. We have analyzed rhythms in two different ways. We have extracted rhythms depending on each melodic pattern, while we have extracted rhythms depending on each bar. The former are complicated and the latter are typical. This result indicates that koto players recognize melodic patterns and rhythmic patterns independently. Our analyses show the melodic patterns and rhythmic patterns that are acquired by koto players. These patterns will be applied to the description of variations of the melisma to build a score database. These patterns will also be applied to a composition and education. The melodic patterns can be extracted from other genres of Japanese traditional music, foreign old folk songs or chants by using this method.

Facilitation of Learning of a Simultaneous Discrimination between Rotated Patterns by Bumblebees

ERIC Educational Resources Information Center

Perreault, M. J.; Plowright, C. M. S.

2009-01-01

The failure to discriminate between a pattern consisting of four orthogonal bars and the same pattern rotated by 45 degrees has been interpreted in the literature as evidence against pictorial representations in honeybees. This study determines whether prior training can facilitate the discrimination. In Experiment 1, one group of bumblebees was…

Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation.

PubMed

Lawrence, Michael A; Leib, Daniel J; Ostrowski, Stephanie J; Carlson, Lara A

2017-05-01

Lawrence, MA, Leib, DJ, Ostrowski, SJ, and Carlson, LA. Nonlinear analysis of an unstable bench press bar path and muscle activation. J Strength Cond Res 31(5): 1206-1211, 2017-Unstable resistance exercises are typically performed to improve the ability of stabilizing muscles to maintain joint integrity under a load. The purpose of this study was to examine the effects of an unstable load (as provided by a flexible barbell and a load suspended by elastic bands) on the bar path, the primary musculature, and stabilizing musculature while bench pressing using nonlinear analyses. Fifteen resistance-trained men (age 24.2 ± 2.7 years, mass 84.1 ± 12.0 kg, height 1.77 ± 0.05 m, 9.9 ± 3.4 years of lifting experience, and bench press 1 repetition maximum (RM) 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (total load 75% 1RM) and unstable (total load 60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and bar stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). During the unstable condition, the bar moved in more ways and was less predictable in the mediolateral and anteroposterior directions. However, the muscle activation patterns of all muscles were more constrained with the unstable barbell. These findings suggest that the unstable condition was more challenging to control, but subjects controlled the instability by contracting their muscles in a more stable pattern or "staying tight" throughout the exercise.

The three-dimensional kinematics of a barbell during the snatch of Taiwanese weightlifters.

PubMed

Chiu, Hung-Ta; Wang, Chih-Hung; Cheng, Kuangyou B

2010-06-01

The purpose of this study is to characterize the trajectory of a barbell and clarify whether there is a standard pattern in the barbell trajectory for each lifter. Two high-speed cameras (mega-speed MS1000, sampling rate=120 Hz) were used to film the barbell trajectories of male Taiwanese weightlifters under competitive conditions. Twenty-four successful lifts were filmed and classified into 3 groups (n=8 per group) by relative barbell-mass (RBM): the better-performance group (RBM>1.63), the middle group (1.28

Clinal variation in the juvenal plumage of American kestrels

USGS Publications Warehouse

Smallwood, J.A.; Natale, C.; Steenhof, K.; Meetz, M.; Marti, C.D.; Melvin, R.J.; Bortolotti, G.R.; Robertson, R.; Robertson, S.; Shuford, W.R.; Lindemann, S.A.; Tornwall, B.

1999-01-01

The American Kestrel(Falco sparverius) is a sexually dichromatic falcon that exhibits considerable individual plumage variability. For example, the anterior extent of the black dorsal barring in juvenile males has been used throughout North America as one of several aging criteria, but recent data demonstrate that the variability among individual Southeastern American Kestrels(E S. paulus)exceeds that accounted for by age. The objective of this study was to search for geographic patterns in the variability of juvenal plumage, particularly those characteristics considered indicative of age. Nestling kestrels (n = 610) were examined prior to fledging during the 1997 breeding season at nest box programs across a large portion of the North American breeding range. From south to north (1) the crown patches of both males and females become more completely rufous, and (2) shaft streaks on forehead and crown feathers become more pronounced, especially in males. Male Southeastern American Kestrels differed from other males (E s. sparverius) in that the anterior extent of dorsal barring averaged less but was more variable. The variability observed in North America appears to be part of a cline extending across the species range in the Western Hemisphere, where tropical subspecies are small and have reduced dorsal barring. Both body size and, especially in males, dorsal barring increases with increasing north and south latitude. We suggest that this geographic pattern is adaptive in terms of thermoregulation, and that differences in the sex roles may explain why males become less barred with maturity while females do not.

Computations of Axisymmetric Flows in Hypersonic Shock Tubes

NASA Technical Reports Server (NTRS)

Sharma, Surendra P.; Wilson, Gregory J.

1995-01-01

A time-accurate two-dimensional fluid code is used to compute test times in shock tubes operated at supersonic speeds. Unlike previous studies, this investigation resolves the finer temporal details of the shock-tube flow by making use of modern supercomputers and state-of-the-art computational fluid dynamic solution techniques. The code, besides solving the time-dependent fluid equations, also accounts for the finite rate chemistry in the hypersonic environment. The flowfield solutions are used to estimate relevant shock-tube parameters for laminar flow, such as test times, and to predict density and velocity profiles. Boundary-layer parameters such as bar-delta(sub u), bar-delta(sup *), and bar-tau(sub w), and test time parameters such as bar-tau and particle time of flight t(sub f), are computed and compared with those evaluated by using Mirels' correlations. This article then discusses in detail the effects of flow nonuniformities on particle time-of-flight behind the normal shock and, consequently, on the interpretation of shock-tube data. This article concludes that for accurate interpretation of shock-tube data, a detailed analysis of flowfield parameters, using a computer code such as used in this study, must be performed.

Crystal defects observed by the etch-pit method and their effects on Schottky-barrier-diode characteristics on (\\bar{2}01) β-Ga2O3

NASA Astrophysics Data System (ADS)

Kasu, Makoto; Oshima, Takayoshi; Hanada, Kenji; Moribayashi, Tomoya; Hashiguchi, Akihiro; Oishi, Toshiyuki; Koshi, Kimiyoshi; Sasaki, Kohei; Kuramata, Akito; Ueda, Osamu

2017-09-01

A pixel array of vertical Schottky-barrier diodes (SBDs) was fabricated and measured on the surface of a (\\bar{2}01) β-Ga2O3 single crystal. Subsequently, etch pits and patterns were observed on the same surface. Three types of etch pits were discovered: (1) a line-shaped etch pattern originating from a void and extending toward the [010] direction, (2) an arrow-shaped etch pit whose arrow’s head faces toward the [102] direction and, (3) a gourd-shaped etch pit whose point head faces toward the [102] direction. Their average densities were estimated to be 5 × 102, 7 × 104, and 9 × 104 cm-2, respectively. We confirmed no clear relationship between the leakage current in SBDs and these crystalline defects. Such results are obtained because threading dislocations run mainly in the [010] growth direction and do not go through the (\\bar{2}01) sample plate.

Estimation of Road Loads and Vibration Transmissibility of Torsion Bar Suspension System in a Tracked Vehicle

NASA Astrophysics Data System (ADS)

Gagneza, G. P. S.; Chandramohan, Sujatha

2018-05-01

Designing the suspension system of a tracked combat vehicle (CV) is really challenging as it has to satisfy conflicting requirements of good ride comfort, vehicle handling and stability characteristics. Many studies in this field have been reported in literature and it has been found that torsion bars satisfy the designer's conflicting requirements of good ride and handling and thus have reserved a place for themselves as the most widely used suspension system for military track vehicles. Therefore, it is imperative to evaluate the effectiveness of the torsion bar under dynamic conditions of undulating terrain and validating the same by correlating it with computer simulation results. Thus in the present work, the dynamic simulation of a 2N + 4 degrees of freedom (DOF) mathematical model has been carried out using MATLAB Simulink and the vibration levels were also measured experimentally on a 12 wheel stationed high mobility military tracked infantry combat vehicle (ICV BMP-II) traversing different terrain, that is, Aberdeen proving ground (APG) and Sinusoidal, at a constant vehicle speed. The dynamic force transmitted to the hull CG through the 12 torsion bar suspension systems was computed to be around 26,700 N and found to match the measured values. The vibration isolation of the torsion bar in bounce was found to be effective, with a transmissibility from the road wheel to the hull of about 0.6.

Study of plastic strain localization mechanisms caused by nonequilibrium transitions in mesodefect ensembles under high-speed loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokovikov, Mikhail, E-mail: sokovikov@icmm.ru; Chudinov, Vasiliy; Bilalov, Dmitry

2015-10-27

The behavior of specimens dynamically loaded during split Hopkinson (Kolsky) bar tests in a regime close to simple shear conditions was studied. The lateral surface of the specimens was investigated in-situ using a high-speed infrared camera CEDIP Silver 450M. The temperature field distribution obtained at different time allowed one to trace the evolution of plastic strain localization. The process of target perforation involving plug formation and ejection was examined using a high-speed infrared camera and a VISAR velocity measurement system. The microstructure of tested specimens was analyzed using an optical interferometer-profiler and a scanning electron microscope. The development of plasticmore » shear instability regions has been simulated numerically.« less

Computer simulations of channel meandering and the formation of point bars: Linking channel dynamics to the preserved stratigraphy

NASA Astrophysics Data System (ADS)

Sun, T.; Covault, J. A.; Pyrcz, M.; Sullivan, M.

2012-12-01

Meandering rivers are probably one of the most recognizable geomorphic features on earth. As they meander across alluvial and delta plains, channels migrate laterally and develop point bars, splays, levees and other geomorphic and sedimentary features that compose substantial portions of the fill within many sedimentary basins. These basins can include hydrocarbon producing fields. Therefore, a good understanding of the processes of meandering channels and their associated deposits is critical for exploiting these reservoirs in the subsurface. In the past couple of decades, significant progress has been made in our understanding of the morphodynamics of channel meandering. Basic fluid dynamics and sediment transport (Ikeda and Parker, 1981; Howard, 1992) has shown that many characteristic features of meandering rivers, such as the meandering wavelength, growth rate and downstream migration rate, can be predicted quantitatively. As a result, a number of variations and improvement of the theory have emerged (e.g., Blondeaux and Seminara, 1985; Parker and Andrews, 1985, 1986; and Sun et al., 2001a, b).The main improvements include the recognition of so called "bar-bend" interactions, where the development of bars on the channel bed and their interactions with the channel bend is recognized as a primary cause for meandering channels to develop greater complexity than the classic goose-neck meander bend shapes, such as compound bend. Recently, Sun and others have shown that the spatial patterns of width variations in meandering channels can be explained by an extrinsic periodic flow variations coupled with the intrinsic bend instability dynamics. In contrast to the significant improvement of our understanding of channel meandering, little work has been done to link the geomorphic features of meandering channels to the geometry and heterogeneity of the deposits they form and ultimately preserves. A computer simulation model based on the work of Sun and others (1996, 2001a,b) is used to investigate the formation and preservation of point bars with meandering rivers. Rather than consisting of a single set of concentric scroll bar like feature as one would expect from the pattern of meandering channels, observations of point bar deposits in map view reveal the previously mentioned complexity in their internal organization. A preserved point bar deposit is often found to be composed of multiple sets of remnant scroll bar like features, each with different orientations. Each set is bounded by the unconformity resulting from one set of the scroll bar like feature truncated by the other set. This study links the channel dynamics to the preserved point bar architectures, and delineates the key controls that affect the point bar internal organization.

Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

PubMed

Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

2017-08-29

With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

National geotechnical centrifuge

NASA Technical Reports Server (NTRS)

Hallam, J. A.; Kunz, N.; Vallotton, W. C.

1982-01-01

A high G-ton centrifuge, able to take a 2700 kg (6000 lb) payload up to 300 G, is described. The stability of dams and embankments, the bearing capacity of soil foundations, and the dynamic behavior of foundations due to vibration of machinery are examples of applications. A power rating of 6,000 kW (9,000 hp) was established for the motor. An acceptable maximum speed of 70 rpm was determined. A speed increase with a ratio of 1:3 is discussed. The isolated tension straps, the anti-spreader bar and the flexwall bucket, and safety precautions are also discussed.

Aluminum-fly ash metal matrix composites for automotive parts. [Reports for April 1 to June 30, 1999, and July 1 to September 30, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, David; Purgert, Robert; Rhudy, Richard

1999-10-15

Some highlights are: (1) During this quarter's field trials, sand mold castings of parts and permanent mold tensile testing bars, K mold bars, and ingots were made from aluminum alloy-fly ash melts. (2) Another objective was met, i.e., to use class ''F'' type precipitator fly ash consisting of particle sizes less than 100 microns. It was possible to pour the composite melt into the sand mold through a filter. (3) Trials were run to determine the required amount of the wetting agent, magnesium, to ensure appropriate mixing of the aluminum alloy and fly ash. The magnesium content required to mixmore » ''F'' fly ash was much lower compared to that required to mix hybrid ''C-F'' fly ash in similar melts. Fly ash particles of less than 100 microns were mixed in aluminum melt. Large scale field trials were undertaken at Eck Industries with the goal of standardizing procedures for producing aluminum-fly ash composite melts and to analyze the structure and properties of the resulting material. Limited testing of tensile properties has been done on pressure die cast parts, and attempts are underway to improve the distribution of fly ash in both sand cast and pressure die cast samples. Eck Industries performed radiographic, heat treatment, and tensile tests on permanent mold cast tensile test bars. After fly ash mixing experiments, the Lanxide high speed-high shear mixer (originally designed for mixing Al-SiC melts) was employed in an attempt to avoid fly ash agglomeration. It led to demixing (instead of deagglomerating) of some fly ash. However, the permanent mold tensile bars poured after high shear mixing displayed good distribution of fly ash in castings. A modified impeller design is being considered for high speed-high shear mixing of aluminum-fly ash melts.« less

Free-vibration acoustic resonance of a nonlinear elastic bar

NASA Astrophysics Data System (ADS)

Tarumi, Ryuichi; Oshita, Yoshihito

2011-02-01

Free-vibration acoustic resonance of a one-dimensional nonlinear elastic bar was investigated by direct analysis in the calculus of variations. The Lagrangian density of the bar includes a cubic term of the deformation gradient, which is responsible for both geometric and constitutive nonlinearities. By expanding the deformation function into a complex Fourier series, we derived the action integral in an analytic form and evaluated its stationary conditions numerically with the Ritz method for the first three resonant vibration modes. This revealed that the bar shows the following prominent nonlinear features: (i) amplitude dependence of the resonance frequency; (ii) symmetry breaking in the vibration pattern; and (iii) excitation of the high-frequency mode around nodal-like points. Stability of the resonant vibrations was also addressed in terms of a convex condition on the strain energy density.

The new Nam Co Multichannel Seismic Campaign in June/July 2016 - Fresh Results and Perspectives for a Future ICDP Drilling Campaign

NASA Astrophysics Data System (ADS)

Daut, G.; Spiess, V.; Haberzettl, T.; Schwenk, T.; Schulze, N.; Haberkern, J.; Bergmann, F.; Gernhardt, F.; Wang, J.; Ju, J.; Huang, L.; Zhu, L.

2016-12-01

In June/July 2016, a multichannel seismic survey was executed on Lake Nam Co to further explore the opportunities for a deep drilling ICDP project. For acquisition, a streamer (Teledyne Inc.) of 64 m active length with 32 single hydrophone was used and sound emission was carried out with a mini GI Gun of 2 x 0.1 L chamber volume, operated at pressures between 50 bar and 140 bar, providing frequencies between 50 Hz and >600 Hz. The data acquired with the MaMuCS recording system were sampled with 1/8 ms for a length of 2 seconds. Additionally, all survey lines were recorded with a parametric echosounder (Innomar SES 200 light) to cover the uppermost ca. 25 m of the sediment sequence (last glacial-Holocene period) in high resolution. These data can serve as a modern analogs for interpreting the deep seismic lines in terms of older glacial-interglacial cycles. 91 seismic profiles were shot using shot rates between 6 and 14 with ship's speed around 4.5 knots during most of the survey, ensuring a good signal/noise ratios and complete coverage of the lake basin. Selected profiles were shot at a speed of 3.0 knots to allow lower frequencies down to 50 Hz to be recorded and to penetrate deeper (>500 ms TWT) into the sedimentary sequence. The basin formation appears to be controlled by the overall tectonic framework revealing significant activity in the latest Quaternary. Extensional, strike-slip and presumably flower structures indicate a complex fault and subsidence pattern, which could not yet be resolved in detail during the field work, but awaits further post-expedition analyses. The dense grid near the thickest sediment packages, assumed to reach back at least to MIS 5 in age, will allow a detailed investigation of sedimentary structures, sediment transport and dispersal patterns. In particular periods of higher and lower lake level can be identified and used as preliminary stratigraphic markers due to their characteristic seismic facies, revealing very low amplitudes at high stand, while lowstand deposits are characterized by higher amplitudes and irregular reflectors. Although the post-processing is still ongoing, the preliminary results show that the data allow to identify promising drilling targets, thus the campaign turned out to be a full success for the anticipated goal of motivating and preparing a potential ICDP drilling proposal.

Investigation of Dynamic Crack Coalescence Using a Gypsum-Like 3D Printing Material

NASA Astrophysics Data System (ADS)

Jiang, Chao; Zhao, Gao-Feng; Zhu, Jianbo; Zhao, Yi-Xin; Shen, Luming

2016-10-01

Dynamic crack coalescence attracts great attention in rock mechanics. However, specimen preparation in experimental study is a time-consuming and difficult procedure. In this work, a gypsum-like material by powder bed and inkjet 3D printing technique was applied to produce specimens with preset cracks for split Hopkinson pressure bar (SHPB) test. From micro X-ray CT test, it was found that the 3D printing technique could successfully prepare specimens that contain preset cracks with width of 0.2 mm. Basic mechanical properties of the 3D printing material, i.e., the elastic modulus, the Poisson's ratio, the density, the compressive strength, the indirect tensile strength, and the fracture toughness, were obtained and reported. Unlike 3D printed specimens using polylactic acid, these gypsum-like specimens can produce failure patterns much closer to those observed in classical rock mechanical tests. Finally, the dynamic crack coalescence of the 3D printed specimens with preset cracks were captured using a high-speed camera during SHPB tests. Failure patterns of these 3D printed specimens are similar to the specimens made by Portland cement concrete. Our results indicate that sample preparation by 3D printing is highly competitive due to its quickness in prototyping, precision and flexibility on the geometry, and high material homogeneity.

The influence of speed and grade on wheelchair propulsion hand pattern.

PubMed

Slowik, Jonathan S; Requejo, Philip S; Mulroy, Sara J; Neptune, Richard R

2015-11-01

The hand pattern used during manual wheelchair propulsion (i.e., full-cycle hand path) can provide insight into an individual's propulsion technique. However, previous analyses of hand patterns have been limited by their focus on a single propulsion condition and reliance on subjective qualitative characterization methods. The purpose of this study was to develop a set of objective quantitative parameters to characterize hand patterns and determine the influence of propulsion speed and grade of incline on the patterns preferred by manual wheelchair users. Kinematic and kinetic data were collected from 170 experienced manual wheelchair users on an ergometer during three conditions: level propulsion at their self-selected speed, level propulsion at their fastest comfortable speed and graded propulsion (8%) at their level self-selected speed. Hand patterns were quantified using a set of objective parameters, and differences across conditions were identified. Increased propulsion speed resulted in a shift away from under-rim hand patterns. Increased grade of incline resulted in the hand remaining near the handrim throughout the cycle. Manual wheelchair users change their hand pattern based on task-specific constraints and goals. Further work is needed to investigate how differences between hand patterns influence upper extremity demand and potentially lead to the development of overuse injuries and pain. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Influence of Speed and Grade on Wheelchair Propulsion Hand Pattern

PubMed Central

Slowik, Jonathan S.; Requejo, Philip S.; Mulroy, Sara J.; Neptune, Richard R.

2015-01-01

Background The hand pattern used during manual wheelchair propulsion (i.e., full-cycle hand path) can provide insight into an individual's propulsion technique. However, previous analyses of hand patterns have been limited by their focus on a single propulsion condition and reliance on subjective qualitative characterization methods. The purpose of this study was to develop a set of objective quantitative parameters to characterize hand patterns and determine the influence of propulsion speed and grade of incline on the patterns preferred by manual wheelchair users. Methods Kinematic and kinetic data were collected from 170 experienced manual wheelchair users on an ergometer during three conditions: level propulsion at their self-selected speed, level propulsion at their fastest comfortable speed, and graded propulsion (8%) at their level self-selected speed. Hand patterns were quantified using a set of objective parameters and differences across conditions were identified. Findings Increased propulsion speed resulted in a shift away from under-rim hand patterns. Increased grade of incline resulted in the hand remaining near the handrim throughout the cycle. Interpretation Manual wheelchair users change their hand pattern based on task-specific constraints and goals. Further work is needed to investigate how differences between hand patterns influence upper extremity demand and potentially lead to the development of overuse injuries and pain. PMID:26228706

Different coordination and flexibility of the spine and pelvis during lateral bending between young and older adults.

PubMed

Sung, Paul S

2016-04-01

This study examined coordination of the spine and pelvis during lateral bending of the trunk in older adults. Thirty-four healthy subjects (17 young and 17 older adults) demonstrated lateral bending at a controlled speed while holding a bar at approximately 180 degrees of shoulder flexion. Kinematic data collection was completed on the thoracic spine, lumbar spine, and pelvis. The coupling angle was calculated to examine the thorax-lumbar, lumbar-pelvis, and thorax-pelvis coordination patterns. The older adults demonstrated a reduced range of motion (ROM) of the lumbar spine, while both groups revealed similar ROM in the thorax and in the pelvis. The coupling angle between the straightening and bending phases was different only for the older adults in the thorax-lumbar (23.4±8.0 vs. -1.6±4.4, p=0.004) and the lumbar-pelvis (65.4±7.2 vs. 86.1±7.8, p=0.001) coordination. However, there was no group difference in the thorax-pelvis coordination. These findings indicate that age-related changes in the lumbar region affect coordination patterns only during the bending phase. The older adults preserved a similar pattern of movement to the young adults during the straightening phase, but the coordination variability of the coupling angles was greater for the older adults than for the young adults. This movement pattern suggests that the older adults lacked consistent trunk control in an attempt to optimize lateral bending coordination. Copyright © 2016 Elsevier B.V. All rights reserved.

Population-level mating patterns and fluctuating asymmetry in swordtail hybrids

NASA Astrophysics Data System (ADS)

Culumber, Zachary W.; Rosenthal, Gil G.

2013-08-01

Morphological symmetry is a correlate of fitness-related traits or even a direct target of mate choice in a variety of taxa. In these taxa, when females discriminate among potential mates, increased selection on males should reduce fluctuating asymmetry (FA). Hybrid populations of the swordtails Xiphophorus birchmanni and Xiphophorus malinche vary from panmictic (unstructured) to highly structured, in which reproductive isolation is maintained among hybrids and parental species. We predicted that FA in flanking vertical bars used in sexual signalling should be lower in structured populations, where non-random mating patterns are observed. FA in vertical bars was markedly lower in structured populations than in parental and unstructured hybrid populations. There was no difference in FA between parentals and hybrids, suggesting that hybridisation does not directly affect FA. Rather, variation in FA likely results from contrasting mating patterns in unstructured and structured populations.

The Density and Compressibility of BaCO3-SrCO3-CaCO3-K2CO3-Na2CO3-Li2CO3 Liquids: New Measurements and a Systematic Trend with Cation Field Strength

NASA Astrophysics Data System (ADS)

Hurt, S. M.; Lange, R. A.; Ai, Y.

2015-12-01

The volumetric properties of multi-component carbonate liquids are required to extend thermodynamic models that describe partial melting of the deep mantle (e.g. pMELTS; Ghiorso et al., 2003) to carbonate-bearing lithologies. Carbonate in the mantle is an important reservoir of carbon, which is released to the atmosphere as CO2 through volcanism, and thus contributes to the carbon cycle. Although MgCO3 is the most important carbonate component in the mantle, it is not possible to directly measure the 1-bar density and compressibility of MgCO3 liquid because, like other alkaline-earth carbonates, it decomposes at a temperature lower than its melting temperature. Despite this challenge, Liu and Lange (2003) and O'Leary et al. (2015) showed that the one bar molar volume, thermal expansion and compressibility of the CaCO3 liquid component could be obtained by measuring the density and sound speeds of stable liquids in the CaCO3-Li2CO3-Na2CO3-K2CO3 quaternary system at one bar. In this study, this same strategy is employed on SrCO3- and BaCO3-bearing alkali carbonate liquids. The density and sound speed of seven liquids in the SrCO3-Li2CO3-Na2CO3-K2CO3 quaternary and three liquids in the BaCO3-Li2CO3-Na2CO3-K2CO3 quaternary were measured from 739-1367K, with SrCO3 and BaCO3 concentrations ranging from 10-50 mol%. The density measurements were made using the double-bob Archimedean method and sound speeds were obtained with a frequency-sweep acoustic interferometer. The molar volume and sound speed measurements were used to calculate the isothermal compressibility of each liquid, and the results show the volumetric properties mix ideally with composition. The partial molar volume and compressibility of the SrCO3 and BaCO3 components are compared to those obtained for the CaCO3 component as a function of cation field strength. The results reveal a systematic trend that allows the partial molar volume and compressibility of the MgCO3 liquid component to be estimated.

Symmetrical Taylor impact of glass bars

NASA Astrophysics Data System (ADS)

Murray, N. H.; Bourne, N. K.; Field, J. E.; Rosenberg, Z.

1998-07-01

Brar and Bless pioneered the use of plate impact upon bars as a technique for investigating the 1D stress loading of glass but limited their studies to relatively modest stresses (1). We wish to extend this technique by applying VISAR and embedded stress gauge measurements to a symmetrical version of the test in which two rods impact one upon the other. Previous work in the laboratory has characterised the glass types (soda-lime and borosilicate)(2). These experiments identify the failure mechanisms from high-speed photography and the stress and particle velocity histories are interpreted in the light of these results. The differences in response of the glasses and the relation of the fracture to the failure wave in uniaxial strain are discussed.

Quantum Mechanics, vacuum, particles, Gödel-Cohen incompleteness and the Universe

NASA Astrophysics Data System (ADS)

Gonzalez-Mestres, Luis

2017-12-01

Are the standard laws of Physics really fundamental principles? Does the physical vacuum have a more primordial internal structure? Are quarks, leptons, gauge bosons… ultimate elementary objects? These three basic questions are actually closely related. If the deep vacuum structure and dynamics turn out to be less trivial than usually depicted, the conventional "elementary" particles will most likely be excitations of such a vacuum dynamics that remains by now unknown. We then expect relativity and quantum mechanics to be low-energy limits of a more fundamental dynamical pattern that generates them at a deeper level. It may even happen that vacuum drives the expansion of the Universe from its own inner dynamics. Inside such a vacuum structure, the speed of light would not be the critical speed for vacuum constituents and propagating signals. The natural scenario would be the superbradyon (superluminal preon) pattern we postulated in 1995, with a new critical speed cs much larger than the speed of light c just as c is much larger than the speed of sound. Superbradyons are assumed to be the bradyons of a super-relativity associated to cs (a Lorentz invariance with cs as the critical speed). Similarly, the standard relativistic space-time with four real coordinates would not necessarily hold beyond low-energy and comparatively local distance scales. Instead, the spinorial space-time (SST) with two complex coordinates we introduced in 1996-97 may be the suitable one to describe the internal structure of vacuum and standard "elementary" particles and, simultaneously, Cosmology at very large distance scales. If the constituents of the preonic vacuum are superluminal, quantum entanglement appears as a natural property provided cs ≫ c . The value of cs can even be possibly found experimentally by studying entanglement at large distances. It is not excluded that preonic constituents of vacuum can exist in our Universe as free particles ("free" superbradyons), in which case we expect them to be weakly coupled to standard matter. If a preonic vacuum is actually leading the basic dynamics of Particle Physics and Cosmology, and standard particles are vacuum excitations, the Gödel-Cohen incompleteness will apply to vacuum dynamics whereas the conventional laws of physics will actually be approximate and have error bars. We discuss here the possible role of the superbradyonic vacuum and of the SST in generating Quantum Mechanics, as well as the implications of such a dynamical origin of the conventional laws of Physics and possible evidences in experiments and observations. Black holes, gravitational waves, possible "free" superbradyons or preonic waves, unconventional vacuum radiation… are considered from this point of view paying particular attention to LIGO, VIRGO and CERN experiments. This lecture is dedicated to the memory of John Bell

Instrument for analysis of electric motors based on slip-poles component

DOEpatents

Haynes, Howard D.; Ayers, Curtis W.; Casada, Donald A.

1996-01-01

A new instrument for monitoring the condition and speed of an operating electric motor from a remote location. The slip-poles component is derived from a motor current signal. The magnitude of the slip-poles component provides the basis for a motor condition monitor, while the frequency of the slip-poles component provides the basis for a motor speed monitor. The result is a simple-to-understand motor health monitor in an easy-to-use package. Straightforward indications of motor speed, motor running current, motor condition (e.g., rotor bar condition) and synthesized motor sound (audible indication of motor condition) are provided. With the device, a relatively untrained worker can diagnose electric motors in the field without requiring the presence of a trained engineer or technician.

Instrument for analysis of electric motors based on slip-poles component

DOEpatents

Haynes, H.D.; Ayers, C.W.; Casada, D.A.

1996-11-26

A new instrument is described for monitoring the condition and speed of an operating electric motor from a remote location. The slip-poles component is derived from a motor current signal. The magnitude of the slip-poles component provides the basis for a motor condition monitor, while the frequency of the slip-poles component provides the basis for a motor speed monitor. The result is a simple-to-understand motor health monitor in an easy-to-use package. Straightforward indications of motor speed, motor running current, motor condition (e.g., rotor bar condition) and synthesized motor sound (audible indication of motor condition) are provided. With the device, a relatively untrained worker can diagnose electric motors in the field without requiring the presence of a trained engineer or technician. 4 figs.

Experimental and numerical study of plastic shear instability under high-speed loading conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokovikov, Mikhail, E-mail: sokovikov@icmm.ru, E-mail: naimark@icmm.ru; Chudinov, Vasiliy, E-mail: sokovikov@icmm.ru, E-mail: naimark@icmm.ru; Bilalov, Dmitry, E-mail: sokovikov@icmm.ru, E-mail: naimark@icmm.ru

2014-11-14

The behavior of specimens dynamically loaded during the split Hopkinson (Kolsky) bar tests in a regime close to simple shear conditions was studied. The lateral surface of the specimens was investigated in a real-time mode with the aid of a high-speed infra-red camera CEDIP Silver 450M. The temperature field distribution obtained at different time made it possible to trace the evolution of plastic strain localization. The process of target perforation involving plug formation and ejection was examined using a high-speed infra-red camera and a VISAR velocity measurement system. The microstructure of tested specimens was analyzed using an optical interferometer-profilometer andmore » a scanning electron microscope. The development of plastic shear instability regions has been simulated numerically.« less

Smooth moves: bar and nightclub tobacco promotions that target young adults.

PubMed

Sepe, Edward; Ling, Pamela M; Glantz, Stanton A

2002-03-01

This article describes the tobacco industry's use of bars and nightclubs to encourage smoking among young adults. Previously secret tobacco industry marketing documents were analyzed. Tobacco industry bar and nightclub promotions in the 1980s and 1990s included aggressive advertising, tobacco brand--sponsored activities, and distribution of samples. Financial incentives for club owners and staff were used to encourage smoking through peer influence. Increased use of these strategies occurred concurrently with an increase in smoking among persons aged 18 through 24 years. The tobacco industry's bar and nightclub promotions are not yet politically controversial and are not regulated by the 1998 Master Settlement Agreement between the industry and the states. Tobacco control advocates should include young adults in research and advocacy efforts and should design interventions to counter this industry strategy to solidify smoking patterns and recruit young adult smokers.

Smooth Moves: Bar and Nightclub Tobacco Promotions That Target Young Adults

PubMed Central

Sepe, Edward; Ling, Pamela M.; Glantz, Stanton A.

2002-01-01

Objectives. This article describes the tobacco industry's use of bars and nightclubs to encourage smoking among young adults. Methods. Previously secret tobacco industry marketing documents were analyzed. Results. Tobacco industry bar and nightclub promotions in the 1980s and 1990s included aggressive advertising, tobacco brand–sponsored activities, and distribution of samples. Financial incentives for club owners and staff were used to encourage smoking through peer influence. Increased use of these strategies occurred concurrently with an increase in smoking among persons aged 18 through 24 years. Conclusions. The tobacco industry's bar and nightclub promotions are not yet politically controversial and are not regulated by the 1998 Master Settlement Agreement between the industry and the states. Tobacco control advocates should include young adults in research and advocacy efforts and should design interventions to counter this industry strategy to solidify smoking patterns and recruit young adult smokers. PMID:11867322

Are running speeds maximized with simple-spring stance mechanics?

PubMed

Clark, Kenneth P; Weyand, Peter G

2014-09-15

Are the fastest running speeds achieved using the simple-spring stance mechanics predicted by the classic spring-mass model? We hypothesized that a passive, linear-spring model would not account for the running mechanics that maximize ground force application and speed. We tested this hypothesis by comparing patterns of ground force application across athletic specialization (competitive sprinters vs. athlete nonsprinters, n = 7 each) and running speed (top speeds vs. slower ones). Vertical ground reaction forces at 5.0 and 7.0 m/s, and individual top speeds (n = 797 total footfalls) were acquired while subjects ran on a custom, high-speed force treadmill. The goodness of fit between measured vertical force vs. time waveform patterns and the patterns predicted by the spring-mass model were assessed using the R(2) statistic (where an R(2) of 1.00 = perfect fit). As hypothesized, the force application patterns of the competitive sprinters deviated significantly more from the simple-spring pattern than those of the athlete, nonsprinters across the three test speeds (R(2) <0.85 vs. R(2) ≥ 0.91, respectively), and deviated most at top speed (R(2) = 0.78 ± 0.02). Sprinters attained faster top speeds than nonsprinters (10.4 ± 0.3 vs. 8.7 ± 0.3 m/s) by applying greater vertical forces during the first half (2.65 ± 0.05 vs. 2.21 ± 0.05 body wt), but not the second half (1.71 ± 0.04 vs. 1.73 ± 0.04 body wt) of the stance phase. We conclude that a passive, simple-spring model has limited application to sprint running performance because the swiftest runners use an asymmetrical pattern of force application to maximize ground reaction forces and attain faster speeds. Copyright © 2014 the American Physiological Society.

Large area thermal target board: An improvement to environmental effects and system parameters characterization

NASA Astrophysics Data System (ADS)

Watkins, Wendell R.; Bean, Brent L.; Munding, Peter D.

1994-06-01

Recent field tests have provided excellent opportunities to use a new characterization tool associated with the Mobile Imaging Spectroscopy Laboratory (MISL) of the Battlefield Environment Directorate, formerly the U.S. Army Atmospheric Sciences Laboratory. The MISL large area (1.8 by 1.8 m, uniform temperature, thermal target) was used for characterization and isolation of phenomena which impact target contrast. By viewing the target board from closeup and distant ranges simultaneously with the MISL thermal imagers, the inherent scene content could be calibrated and the degrading effects of atmospheric propagation could be isolated. The target board is equipped with several spatial frequency bar patterns, but only the largest 3.5-cycle full area bar pattern was used for the distant range of 1.6 km. The quantities measured with the target board include the inherent background change, the contrast transmission, and the atmospheric modulation transfer function. The MISL target board has a unique design which makes it lightweight with near perfect transition between the hot and cold portions of the bar pattern. The heated portion of the target is an elongated rectangular even which is tilted back at a 30 deg angle to form a 1.8 by 1.8 m square when viewed from the front. The cold bars we positioned in front of the heated oven surface and can be oriented in either the vertical or horizontal direction. The oven is mounted on a lightweight trailer for one- or two-man positioning. An attached metal and canvas structure is used to shield the entire target from both solar loading and cooling winds. The target board has a thin aluminum sheet front surface which is insulated from the oven's heating structure.

Magnetic fields and orientation in homing pigeons: experiments of the late W. T. Keeton.

PubMed Central

Moore, B R

1988-01-01

The late W. T. Keeton conducted 35 experiments examining the effects of bar magnets upon the navigation of experienced homing pigeons on overcast days. Six statistics summarize the consistency and accuracy of the birds' initial orientation and the speed and success of their subsequent homing. Magnets had no significant overall effect upon these measures. PMID:3387447

The Effect of Format and Organization on Extrapolation and Interpolation with Multiple Trend Displays.

ERIC Educational Resources Information Center

Wolfe, Mary L.; Martuza, Victor R.

The major purpose of this experiment was to examine the effects of format (bar graphs vs. tables) and organization (by year vs. by brand) on the speed and accuracy of extrapolation and interpolation with multiple, nonlinear trend displays. Fifty-six undergraduates enrolled in the College of Education at the University of Delaware served as the…

Effects of different roller/crimper designs and rolling speed on rye cover crop termination and seedcotton yield in A no-till system

USDA-ARS?s Scientific Manuscript database

Rollers/crimpers have been utilized in no-till systems to mechanically terminate cover crops as a substitute for chemical termination; however, excessive vibration generated by the original straight bar roller adopted from Brazil has delayed its adoption in the U.S. To reduce excessive vibration, pr...

Dynamic compressive properties obtained from a split Hopkinson pressure bar test of Boryeong shale

NASA Astrophysics Data System (ADS)

Kang, Minju; Cho, Jung-Woo; Kim, Yang Gon; Park, Jaeyeong; Jeong, Myeong-Sik; Lee, Sunghak

2016-09-01

Dynamic compressive properties of a Boryeong shale were evaluated by using a split Hopkinson pressure bar, and were compared with those of a Hwangdeung granite which is a typical hard rock. The results indicated that the dynamic compressive loading reduced the resistance to fracture. The dynamic compressive strength was lower in the shale than in the granite, and was raised with increasing strain rate by microcracking effect as well as strain rate strengthening effect. Since the number of microcracked fragments increased with increasing strain rate in the shale having laminated weakness planes, the shale showed the better fragmentation performance than the granite at high strain rates. The effect of transversely isotropic plane on compressive strength decreased with increasing strain rate, which was desirable for increasing the fragmentation performance. Thus, the shale can be more reliably applied to industrial areas requiring good fragmentation performance as the striking speed of drilling or hydraulic fracturing machines increased. The present dynamic compressive test effectively evaluated the fragmentation performance as well as compressive strength and strain energy density by controlling the air pressure, and provided an important idea on which rock was more readily fragmented under dynamically processing conditions such as high-speed drilling and blasting.

Highly selective stir bar coated with dummy molecularly imprinted polymers for trace analysis of bisphenol A in milk.

PubMed

Zhan, Wen; Wei, Fangdi; Xu, Guanhong; Cai, Zheng; Du, Shuhu; Zhou, Xuemin; Li, Fei; Hu, Qin

2012-04-01

A water compatible molecularly imprinted polymers (MIPs) coated stir bar for bisphenol A(BPA) was prepared with 3,3',5,5'-tetrabromobisphenol A as the dummy template molecule in this study. The dummy molecularly imprinted polymers coated stir bar (DMIPs-SB) showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers when used to extract BPA and its three analogues. The saturated adsorption amount of the DMIPs coating was 3.0 times over that of the non-imprinted polymers coating. To achieve the optimum extraction performance, several parameters, including extraction and desorption time, pH value, adsorption temperature and stirring speed were investigated. The high-performance liquid chromatography combined with the DMIPs-SB was employed in the analysis of BPA in aqueous solution. The linear range of BPA concentration in aqueous medium was 0.0228-2.28 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 6.84 × 10(-3) ng/mL based on three times ratio of signal to noise. This method was directly applied to the determination of trace BPA in milk with satisfactory results. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of injection pressure on performance, emission, and combustion characteristics of diesel-acetylene-fuelled single cylinder stationary CI engine.

PubMed

Srivastava, Anmesh Kumar; Soni, Shyam Lal; Sharma, Dilip; Jain, Narayan Lal

2018-03-01

In this paper, the effect of injection pressure on the performance, emission, and combustion characteristics of a diesel-acetylene fuelled single cylinder, four-stroke, direct injection (DI) diesel engine with a rated power of 3.5 kW at a rated speed of 1500 rpm was studied. Experiments were performed in dual-fuel mode at four different injection pressures of 180, 190, 200, and 210 bar with a flow rate of 120 LPH of acetylene and results were compared with that of baseline diesel operation. Experimental results showed that highest brake thermal efficiency of 27.57% was achieved at injection pressure of 200 bar for diesel-acetylene dual-fuel mode which was much higher than 23.32% obtained for baseline diesel. Carbon monoxide, hydrocarbon, and smoke emissions were also measured and found to be lower, while the NO x emissions were higher at 200 bar in dual fuel mode as compared to those in other injection pressures in dual fuel mode and also for baseline diesel mode. Peak cylinder pressure, net heat release rate, and rate of pressure rise were also calculated and were higher at 200 bar injection pressure in dual fuel mode.

Palateless custom bar supported overdenture: a treatment modality to treat patient with severe gag reflex.

PubMed

Singh, Kunwarjeet; Gupta, Nidhi

2012-01-01

To suggest a custom bar supported overdenture treatment modality for prosthodontic management of patients with severe gag reflex. Some patients have a severe gag reflex and cannot tolerate conventional maxillary complete dentures with maximum palatal coverage and extensions of all borders. The condition further gets complicated in patients suffering from respiratory problems along with severe gag reflex. Severe gagging acts as a barrier to treat such patients with accepted clinical procedures and prevent patients from wearing the prosthesis. By saving some of the remaining natural teeth and fabricating, a horse shoe shape palateless simple tooth or bar supported overdenture can be successfully used for treating such patients. The remaining maxillary right and left canines were prepared with the tapered round end diamond bur to receive copings of custom bar after intentional root canal treatment of same teeth. Impression was made with light body and putty of the polyvinyl siloxane elastomer with double step putty wash technique. Impression was poured with die stone. Wax pattern of copings with bar was fabricated with inlay wax which was invested and casted. After retrieving the bar, it was finished and its fit was evaluated. The coping-bar assembly was finally cemented with the glass ionomer cement. Palateless overdenture was fabricated by conventional technique used for the fabrication of complete denture. Palateless custom bar supported overdenture procedure can be successfully used for the management of patients with severe gag reflex with improved denture retention, stability, chewing efficiency and comfort of the patient.

Solar-cycle Variations of Meridional Flows in the Solar Convection Zone Using Helioseismic Methods

NASA Astrophysics Data System (ADS)

Lin, Chia-Hsien; Chou, Dean-Yi

2018-06-01

The solar meridional flow is an axisymmetric flow in solar meridional planes, extending through the convection zone. Here we study its solar-cycle variations in the convection zone using SOHO/MDI helioseismic data from 1996 to 2010, including two solar minima and one maximum. The travel-time difference between northward and southward acoustic waves is related to the meridional flow along the wave path. Applying the ray approximation and the SOLA inversion method to the travel-time difference measured in a previous study, we obtain the meridional flow distributions in 0.67 ≤ r ≤ 0.96R ⊙ at the minimum and maximum. At the minimum, the flow has a three-layer structure: poleward in the upper convection zone, equatorward in the middle convection zone, and poleward again in the lower convection zone. The flow speed is close to zero within the error bar near the base of the convection zone. The flow distribution changes significantly from the minimum to the maximum. The change above 0.9R ⊙ shows two phenomena: first, the poleward flow speed is reduced at the maximum; second, an additional convergent flow centered at the active latitudes is generated at the maximum. These two phenomena are consistent with the surface meridional flow reported in previous studies. The change in flow extends all the way down to the base of the convection zone, and the pattern of the change below 0.9R ⊙ is more complicated. However, it is clear that the active latitudes play a role in the flow change: the changes in flow speed below and above the active latitudes have opposite signs. This suggests that magnetic fields could be responsible for the flow change.

C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder.

PubMed

Yu, Chunhe; Hu, Bin

2012-02-15

A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

New Titan Saltation Threshold Experiments: Investigating Current and Past Climates

NASA Astrophysics Data System (ADS)

Bridges, N.; Burr, D. M.; Marshall, J.; Smith, J. K.; Emery, J. P.; Horst, S. M.; Nield, E.; Yu, X.

2015-12-01

Titan exhibits aeolian sand dunes that cover ~20% of its surface, attesting to significant sediment transport by the wind. Recent experiments in the Titan Wind Tunnel (TWT) at NASA Ames Research Center [1,2] found that the threshold friction speed needed to detach Titanian "sand" is about 50% higher than previous estimates based on theory alone [3], a result that might be explained by the low ratio of particle to fluid density on the body [1]. Following the successful completion of the initial Titan threshold tests, we are conducting new experiments that expand the pressure range above and below current Titan values. The basic experimental techniques are described in [1], with minor updates to the instrumentation as described in [2]. To reproduce the kinematic viscosity and particle friction Reynolds number equivalent to that expected for Titan's nitrogen atmosphere at 1.4 bars and 94 K requires that TWT be pressurized to 12.5 bars for air at 293K. In addition to running experiments at this pressure to reproduce previous results [1] and investigate low density (high density ratio) materials, TWT pressures of 3 and 8 bars are in the experimental matrix to understand threshold under past Titan conditions when the atmospheric pressure may have been lower [4]. Higher pressures, at 15 and 20 bars in TWT, are also being run to understand the putative effects of low density ratio conditions. Our experimental matrix for this follow-on work uses some of the same materials as previously used, including walnut shells, basalt, quartz, glass spheres, and various low density materials to better simulate the gravity-equivalent weight of Titan sand. For these experiments, the TWT is now equipped with a new high pressure Tavis transducer with sufficient sensitivity to measure freestream speeds of less than 0.5 m s-1 at 12.5 bars. New techniques include video documentation of the experiments. We are also investigating methods of measuring humidity of the wind tunnel environment and electrostatic forces to assess their effect on threshold. [1] Burr, D.M. et al. [2015], Nature, 517, 60-67. [2] Burr, D.M. et al. [2015], Aeolian Res., in press [3] Iversen, J.D. and B.R. White (1982), Sedimentology, 29, 111-119. [4] Charnay, B. et al. [2014], Icarus, 241, 269-279.

Analytical and finite element simulation of a three-bar torsion spring

NASA Astrophysics Data System (ADS)

Rădoi, M.; Cicone, T.

2016-08-01

The present study is dedicated to the innovative 3-bar torsion spring used as suspension solution for the first time at Lunokhod-1, the first autonomous vehicle sent for the exploration of the Moon in the early 70-ies by the former USSR. The paper describes a simple analytical model for calculation of spring static characteristics, taking into account both torsion and bending effects. Closed form solutions of this model allows quick and elegant parametric analysis. A comparison with a single torsion bar with the same stiffness reveal an increase of the maximum stress with more than 50%. A 3D finite element (FE) simulation is proposed to evaluate the accuracy of the analytical model. The model was meshed in an automated pattern (sweep for hubs and tetrahedrons for bars) with mesh morphing. Very close results between analytical and numerical solutions have been found, concluding that the analytical model is accurate. The 3-D finite element simulation was used to evaluate the effects of design details like fillet radius of the bars or contact stresses in the hex hub.

Wear evaluation of flank in burins of high speed steel modified with titanium ions

NASA Astrophysics Data System (ADS)

E Caballero, J.; V-Niño, E. D.

2017-12-01

This report shows the results obtained researching the flank wearing resistance performed by the high-speed steel (HSS) burins without any surface treatment (reference substrate) and others with surface treatment based on Titanium ions. The flank wearing was carried out by means of an industrial process by chip removal with repetitive tests of dry finished turning of AISI/SAE 1045 steel bars. The useful service life of the burins was evaluated according to ISO 3685:1993, and it was found that the burins treated with Titanium ions showed an increase in the flank wearing resistance with respect to the ones used as reference.

An assessment of sauger population characteristics on two Tennessee River reservoirs

USGS Publications Warehouse

Graham, Christy L.; Bettoli, Phillip William; Churchill, Timothy N.

2015-01-01

In 1992, a 356-mm minimum length limit (MLL) was enacted on Kentucky Lake and a 381-mm MLL was enacted on Watts Bar Lake, two mainstem reservoirs on the Tennessee River, in an attempt to reduce exploitation and improve the size structure of the sauger (Sander canadensis) populations. The objectives of this study were to compare sauger population characteristics immediately following (1993–1994) and 15 years after (2008–2009) the regulations took effect, examine spatial and temporal patterns in growth, examine recruitment patterns in each reservoir using a recruitment variability index (RVI), and assess the current likelihood of overfishing. Saugers were collected with experimental gill nets in each reservoir and aged using otoliths. A Beverton-Holt yield-per-recruit model was used to simulate angler yields and estimate the likelihood of growth overfishing. Recruitment overfishing was assessed by examining spawning potential ratios under various MLL and exploitation rate scenarios. The sauger population in Kentucky Lake experienced modest improvements in size and age structure over the 15 years following enactment of more restrictive harvest regulations, whereas the population in Watts Bar Lake changed very little, if at all, in terms of size and age structure. Mean lengths of age-3 sauger were significantly greater in Watts Bar Lake than in Kentucky Lake in both time periods. The RVI values indicated that between 1993 and 2009 the sauger in Kentucky Lake displayed more stable recruitment than the Watts Bar Lake population. Neither population exhibited signs of growth overfishing in 2008–09 under the current length limits; however, the Watts Bar Lake population would be susceptible to recruitment overfishing at high (>40%) exploitation rates if natural mortality was as low as 20%. These analyses have demonstrated that the Watts Bar Lake and Kentucky Lake populations, in terms of size and age structure, have remained relatively stable over 15+ years and the MLLs appear to be conserving the stocks.

Contribution to volatile organic compound exposures from time spent in stores and restaurants and bars.

PubMed

Loh, Miranda M; Houseman, E Andres; Levy, Jonathan I; Spengler, John D; Bennett, Deborah H

2009-11-01

Many people spend time in stores and restaurants, yet there has been little investigation of the influence of these microenvironments on personal exposure. Relative to the outdoors, transportation, and the home, these microenvironments have high concentrations of several volatile organic compounds (VOCs). We developed a stochastic model to examine the effect of VOC concentrations in these microenvironments on total personal exposure for (1) non-smoking adults working in offices who spend time in stores and restaurants or bars and (2) non-smoking adults who work in these establishments. We also compared the effect of working in a smoking versus non-smoking restaurant or bar. Input concentrations for each microenvironment were developed from the literature whereas time activity inputs were taken from the National Human Activity Patterns Survey. Time-averaged exposures were simulated for 5000 individuals over a weeklong period for each analysis. Mean contributions to personal exposure from non-working time spent in stores and restaurants or bars range from <5% to 20%, depending on the VOC and time-activity patterns. At the 95th percentile of the distribution of the proportion of personal exposure attributable to time spent in stores and restaurants or bars, these microenvironments can be responsible for over half of a person's total exposure to certain VOCs. People working in restaurants or bars where smoking is allowed had the highest fraction of exposure attributable to their workplace. At the median, people who worked in stores or restaurants tended to have 20-60% of their total exposures from time spent at work. These results indicate that stores and restaurants can be large contributors to personal exposure to VOCs for both workers in those establishments and for a subset of people who visit these places, and that incorporation of these non-residential microenvironments can improve models of personal exposure distributions.

A New Species of Tiger Pleco Panaqolus (Siluriformes: Loricariidae) from the Xingu Basin, Brazil

PubMed Central

Melo de Sousa, Leandro

2016-01-01

Panaqolus tankei is described from the Xingu River, Brazil. The new species is diagnosed from P. albomaculatus, P. dentex, P. nix, P. nocturnus, and P. koko by its color pattern consisting of dark and light diagonal bars on the body and bands on the fins (vs. body and fins without bars or bands); from P. albivermis, P. maccus, and P. purusiensis by the width of the dark bars being more or less the same of the light bars (vs. dark bars at least two or three times wider than light bars) and from P. changae by the absence of vermiculation on the head (vs. vermiculation present on head). The new species differs from P. gnomus by the orientation of the bars from posterodorsal to anteroventral direction (vs. anterodorsal to posteroventral direction), and from P. claustellifer by the orientation of the bands in the dorsal fin that are not parallel to the margin (vs. parallel to the margin). The barcoding region (COI) was sequenced for the new species, sequences were deposited in GenBank and were compared with congeners from other drainages. With regard to the current construction of a hydroelectric power plant (a so-called mega dam) in the Xingu River, herewith we increase knowledge of the river Xingu’s ichthyofauna and, thus improve the assessment of the impacts of that construction on the river. PMID:27828981

A New Species of Tiger Pleco Panaqolus (Siluriformes: Loricariidae) from the Xingu Basin, Brazil.

PubMed

Cramer, Christian Andreas; Melo de Sousa, Leandro

2016-01-01

Panaqolus tankei is described from the Xingu River, Brazil. The new species is diagnosed from P. albomaculatus, P. dentex, P. nix, P. nocturnus, and P. koko by its color pattern consisting of dark and light diagonal bars on the body and bands on the fins (vs. body and fins without bars or bands); from P. albivermis, P. maccus, and P. purusiensis by the width of the dark bars being more or less the same of the light bars (vs. dark bars at least two or three times wider than light bars) and from P. changae by the absence of vermiculation on the head (vs. vermiculation present on head). The new species differs from P. gnomus by the orientation of the bars from posterodorsal to anteroventral direction (vs. anterodorsal to posteroventral direction), and from P. claustellifer by the orientation of the bands in the dorsal fin that are not parallel to the margin (vs. parallel to the margin). The barcoding region (COI) was sequenced for the new species, sequences were deposited in GenBank and were compared with congeners from other drainages. With regard to the current construction of a hydroelectric power plant (a so-called mega dam) in the Xingu River, herewith we increase knowledge of the river Xingu's ichthyofauna and, thus improve the assessment of the impacts of that construction on the river.

Combined experimental and numerical approach to evaluate impact scaling relations and reproducibility of craters produced at the Experimental Projectile Impact Chamber (E.P.I.C., Centro de Astrobiología, Spain.)

NASA Astrophysics Data System (ADS)

Ormö, J.; Wünnemann, K.; Collins, G.; Melero Asensio, I.

2012-04-01

The Experimental Projectile Impact Chamber at Centro de Astrobiología, Spain, consists of a 7m wide, funnel-shaped test bed, and a 20.5mm caliber compressed N2 gas gun. The test bed can be filled with any type of target material, but is especially designed for wet target experiments. The shape and size aim to decrease disturbance from reflected surface waves in wet target experiments. Experiments are done under 1Atm pressure. The gas gun can launch projectiles of any material and dimensions <20mm (smaller diameters using sabots), and at any angle from vertical to near horizontal. The projectile velocities are of the order of a few hundreds of meters per second depending mainly on the gas pressure, as well as projectile diameter and density. When using a dry sand target a transient crater about 30cm wide is produced. Wet target experiments have not yet been performed in this newly installed test chamber, but transient cavities in water are expected to be in the order of 50-70cm wide. The large scale allows for detailed study of the dynamics of cratering motions during the stages of crater growth and subsequent collapse, especially in wet targets. These observations provide valuable benchmark data for numerical simulations and for comparison with field studies. Here we describe the results of ten impact experiments using three different gas pressures (100bar, 180bar, 200bar), two projectile compositions (20mm, 5.7g delrin; 20mm, 16.3g Al2O3), and two different impact angles (90˚ and 53˚ over the horizontal plane). Nine of the experiments were done in a quarter-space geometry using a specially designed camera tank with a 45mm thick glass window. One experiment was done in half-space geometry as reference. The experiments were recorded with a high-speed digital video camera, and the resulting craters were documented with a digital still frame camera. Projectile velocities are estimated with a combination of tracking software and a Shooting Chrony Alpha M-1 chronograph to be about 330m/s for delrin (100bar), 220m/s for Al2O3 (100bar), 400m/s for delrin (200bar), and 275m/s for Al2O3 (200bar). The velocities for the lighter delrin projectile and at the higher pressure are above the speed of sound in dry silica sand (243 m/s; Sandia report SAND2007-3524). The experimental set up (i.e. target material, projectile density and velocity, impact angle), as well as the dimensions of the resulting craters, are used as inputs in numerical simulation using the iSALE computational code. Results from these simulations will be presented and compared with the experiments.

Biomechanics of front and back squat exercises

NASA Astrophysics Data System (ADS)

Braidot, A. A.; Brusa, M. H.; Lestussi, F. E.; Parera, G. P.

2007-11-01

Squat constitutes one of the most popular exercises to strengthen the muscles of the lower limbs. It is considered one of the most widely spread exercises for muscle sport training and is part of the competition movements comprised within olympic weight-lifting. In physical rehabilitation, squats are used for muscular recovery after different injuries of the lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-squats are generally used, in a knee flexion motion range from 0° to 50° because in this range the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to greater flexion angles. The aim of this work is to make a comparative bidimensional study of the kinematic and dynamic variables of the excecution of the parallel squat exercise with the front and back bar. It is observed in the knee a better development of energy with the front bar, allowing a better muscular exercise with the same load. The mean power absorbed by the hip with the back bar is considerably greater, associated to the speed of the gesture.

The trans-Himalayan flights of bar-headed geese (Anser indicus)

USGS Publications Warehouse

Hawkes, L.A.; Balachandran, S.; Batbayar, N.; Butler, P.J.; Frappell, P.B.; Milsom, W.K.; Tseveenmyadag, N.; Newman, S.H.; Scott, G.R.; Sathiyaselvam, P.; Takekawa, John Y.; Wikelski, M.; Bishop, C.M.

2011-01-01

Birds that fly over mountain barriers must be capable of meeting the increased energetic cost of climbing in low-density air, even though less oxygen may be available to support their metabolism. This challenge is magnified by the reduction in maximum sustained climbing rates in large birds. Bar-headed geese (Anser indicus) make one of the highest and most iconic transmountain migrations in the world. We show that those populations of geese that winter at sea level in India are capable of passing over the Himalayas in 1 d, typically climbing between 4,000 and 6,000min 7-8 h. Surprisingly, these birds do not rely on the assistance of upslope tailwinds that usually occur during the day and can support minimum climb rates of 0.8-2.2 km??h-1, even in the relative stillness of the night. They appear to strategically avoid higher speed winds during the afternoon, thus maximizing safety and control during flight. It would seem, therefore, that bar-headed geese are capable of sustained climbing flight over the passes of the Himalaya under their own aerobic power.

MRTD: man versus machine

NASA Astrophysics Data System (ADS)

van Rheenen, Arthur D.; Taule, Petter; Thomassen, Jan Brede; Madsen, Eirik Blix

2018-04-01

We present Minimum-Resolvable Temperature Difference (MRTD) curves obtained by letting an ensemble of observers judge how many of the six four-bar patterns they can "see" in a set of images taken with different bar-to-background contrasts. The same images are analyzed using elemental signal analysis algorithms and machine-analysis based MRTD curves are obtained. We show that by adjusting the minimum required signal-to-noise ratio the machine-based MRTDs are very similar to the ones obtained with the help of the human observers.

The initial instability and finite-amplitude stability of alternate bars in straight channels

USGS Publications Warehouse

Nelson, J.M.

1990-01-01

The initial instability and fully developed stability of alternate bars in straight channels are investigated using linearized and nonlinear analyses. The fundamental instability leading to these features is identified through a linear stability analysis of the equations governing the flow and sediment transport fields. This instability is explained in terms of topographically induced steering of the flow and the associated pattern of erosion and deposition on the bed. While the linear theory is useful for examining the instability mechanism, this approach is shown to yield relatively little information about well-developed alternate bars and, specifically, the linear analysis is shown to yield poor predictions of the fully developed bar wavelength. A fully nonlinear approach is presented that permits computation of the evolution of these bed features from an initial perturbation to their fully developed morphology. This analysis indicates that there is typically substantial elongation of the bar wavelength during the evolution process, a result that is consistent with observations of bar development in flumes and natural channels. The nonlinear approach demonstrates that the eventual stability of these features is a result of the interplay between topographic steering effects, secondary flow production as a result of streamline curvature, and gravitationally induced modifications of sediment fluxes over a sloping bed. ?? 1990.

Mechanical-plowing-based high-speed patterning on hard material via advanced-control and ultrasonic probe vibration.

PubMed

Wang, Zhihua; Tan, Jun; Zou, Qingze; Jiang, Wei

2013-11-01

In this paper, we present a high-speed direct pattern fabrication on hard materials (e.g., a tungsten-coated quartz substrate) via mechanical plowing. Compared to other probe-based nanolithography techniques based on chemical- and/or physical-reactions (e.g., the Dip-pen technique), mechanical plowing is meritorious for its low cost, ease of process control, and capability of working with a wide variety of materials beyond conductive and/or soft materials. However, direct patterning on hard material faces two daunting challenges. First, the patterning throughput is ultimately hindered by the "writing" (plowing) speed, which, in turn, is limited by the adverse effects that can be excited/induced during high-speed, and/or large-range plowing, including the vibrational dynamics of the actuation system (the piezoelectric actuator, the cantilever, and the mechanical fixture connecting the cantilever to the actuator), the dynamic cross-axis coupling between different axes of motion, and the hysteresis and the drift effects related to the piezoelectric actuators. Secondly, it is very challenging to directly pattern on ultra-hard materials via plowing. Even with a diamond probe, the line depth of the pattern via continuous plowing on ultra-hard materials such as tungsten, is still rather small (<0.5 nm), particularly when the "writing" speed becomes high. To overcome these two challenges, we propose to utilize a novel iterative learning control technique to achieve precision tracking of the desired pattern during high-speed, large-range plowing, and introduce ultrasonic vibration of the probe in the normal (vertical) direction during the plowing process to enable direct patterning on ultra hard materials. The proposed approach was implemented to directly fabricate patterns on a mask with tungsten coating and quartz substrate. The experimental results demonstrated that a large-size pattern of four grooves (20 μm in length with 300 nm spacing between lines) can be fabricated at a high speed of ~5 mm/s, with the line width and the line depth at ~95 nm and 2 nm, respectively. A fine pattern of the word "NANO" is also fabricated at the speed of ~5 mm/s.

Taylor impact of glass bars

NASA Astrophysics Data System (ADS)

Murray, Natalie; Bourne, Neil; Field, John

1997-07-01

Brar and Bless pioneeered the use of plate impact upon bars as a technique for investigating the 1D stress loading of glass. We wish to extend this technique by applying VISAR and embedded stress gauge measurements to a symmetrical version of the test. In this configuration two rods impact one upon the other in a symmetrical version of the Taylor test geometry in which the impact is perfectly rigid in the centre of mass frame. Previous work in the laboratory has characterised the three glass types (float, borosilicate and a high density lead glass). These experiments will identify the 1D stress failure mechanisms from high-speed photography and the stress and particle velocity histories will be interpreted in the light of these results. The differences in response of the three glasses will be highlighted.

Tracking multiple objects is limited only by object spacing, not by speed, time, or capacity.

PubMed

Franconeri, S L; Jonathan, S V; Scimeca, J M

2010-07-01

In dealing with a dynamic world, people have the ability to maintain selective attention on a subset of moving objects in the environment. Performance in such multiple-object tracking is limited by three primary factors-the number of objects that one can track, the speed at which one can track them, and how close together they can be. We argue that this last limit, of object spacing, is the root cause of all performance constraints in multiple-object tracking. In two experiments, we found that as long as the distribution of object spacing is held constant, tracking performance is unaffected by large changes in object speed and tracking time. These results suggest that barring object-spacing constraints, people could reliably track an unlimited number of objects as fast as they could track a single object.

A Rabi, an Imam, and a Priest Walk into a Bar ... Or, What Can Music Education Philosophy Learn from Comparative Cosmopolitanism?

ERIC Educational Resources Information Center

Schmidt, Patrick

2013-01-01

In the face of globalization, speed communication, and the mashing up of once clearly drawn borders, it seems both pertinent and constructive that music education philosophers make use of comparative frameworks to make sense--and make new sense--of educational and musical events, products, and interactions. However, comparison that is merely…

A Rabi, an Imam, and a Priest Walk into a Bar . . . or , What Can Music Education Philosophy Learn from Comparative Cosmopolitanism?

ERIC Educational Resources Information Center

Schmidt, Patrick

2013-01-01

In the face of globalization, speed communication, and the mashing up of once clearly drawn borders, it seems both pertinent and constructive that music education philosophers make use of comparative frameworks to make sense--and make new sense--of educational and musical events, products, and interactions. However, comparison that is merely…

Behavior of fragmentation front in a porous viscoelastic material

NASA Astrophysics Data System (ADS)

Ichihara, M.; Takayama, K.

2002-12-01

We are developing laboratory experiments to investigate dynamics of magma fragmentation during explosive volcanic eruptions. Fragmentation of such a mixture as magma consisting of viscoelastic melt, bubbles and solid particles, is not known yet, and experiments are necessary to establish a mathematical model. It has been shown that viscoelastic silicone compound (Dow Corning 3179) is a useful analogous material to simulate magma fragmentation. In the previous work, a porous specimen made of the compound was rapidly decompressed and development of brittle fragmentation was observed. However, there were arguments that the experiment was different from actual processes which produce fragments as small as volcanic ash, because in the experiment the specimen was broken into only several pieces. This time, results of the improved experiments are presented. The experimental apparatus is a kind of a vertical shock tube, which mainly consists of a high pressure test section and low pressure chambers. The test section is made of acrylic tube of which inner diameter is 25 mm. The internal phenomenon is recorded by a high-speed video camera. Pressure is measured in the gas above and beneath the specimen by piezoelectric transducers. The specimen is prepared in the following way. First, an acrylic tube filled with the compound is put in a nitrogen tank and kept at 45 bar for more than 8 hours. The compound absorbs the gas and equilibrates with the nitrogen. Next, the tank is decompressed back to the atmospheric pressure slowly. Nitrogen exsolves and bubbles are formed in the compound quite uniformly. Finally, the expanded compound sticking out of both ends of the tube is cut down, and the tube containing the specimen is attached to the shock tube. The specimen is rapidly decompressed by 24, 16, and 8 bars. The high-speed video images demonstrate a sequence of the fragmentation process. We observe propagation of a clear fracture front at 50 m/s for 24 bar of decompression and at smaller speed for smaller decompression. The pressure change associated with development of the fragmentation is analyzed and effects of over pressure in the pores and permeable gas flow on fragmentation behavior are discussed.

High-speed imaging using compressed sensing and wavelength-dependent scattering (Conference Presentation)

NASA Astrophysics Data System (ADS)

Shin, Jaewook; Bosworth, Bryan T.; Foster, Mark A.

2017-02-01

The process of multiple scattering has inherent characteristics that are attractive for high-speed imaging with high spatial resolution and a wide field-of-view. A coherent source passing through a multiple-scattering medium naturally generates speckle patterns with diffraction-limited features over an arbitrarily large field-of-view. In addition, the process of multiple scattering is deterministic allowing a given speckle pattern to be reliably reproduced with identical illumination conditions. Here, by exploiting wavelength dependent multiple scattering and compressed sensing, we develop a high-speed 2D time-stretch microscope. Highly chirped pulses from a 90-MHz mode-locked laser are sent through a 2D grating and a ground-glass diffuser to produce 2D speckle patterns that rapidly evolve with the instantaneous frequency of the chirped pulse. To image a scene, we first characterize the high-speed evolution of the generated speckle patterns. Subsequently we project the patterns onto the microscopic region of interest and collect the total light from the scene using a single high-speed photodetector. Thus the wavelength dependent speckle patterns serve as high-speed pseudorandom structured illumination of the scene. An image sequence is then recovered using the time-dependent signal received by the photodetector, the known speckle pattern evolution, and compressed sensing algorithms. Notably, the use of compressed sensing allows for reconstruction of a time-dependent scene using a highly sub-Nyquist number of measurements, which both increases the speed of the imager and reduces the amount of data that must be collected and stored. We will discuss our experimental demonstration of this approach and the theoretical limits on imaging speed.

Stability diagrams for the surface patterns of GaN(0001bar) as a function of Schwoebel barrier height

NASA Astrophysics Data System (ADS)

Krzyżewski, Filip; Załuska-Kotur, Magdalena A.

2017-01-01

Height and type of Schwoebel barriers (direct or inverse) decides about the character of the surface instability. Different surface morphologies are presented. Step bunches, double steps, meanders, mounds and irregular patterns emerge at the surface as a result of step (Schwoebel) barriers at some temperature or miscut values. The study was carried out on the two-component kinetic Monte Carlo (kMC) model of GaN(0001bar) surface grown in nitrogen rich conditions. Diffusion of gallium adatoms over N-polar surface is slow and nitrogen adatoms are almost immobile. We show that in such conditions surfaces remain smooth when gallium adatoms diffuse in the presence of low inverse Schwoebel barrier. It is illustrated by adequate stability diagrams for surface morphologies.

Gravitational radiation from rapidly rotating nascent neutron stars

NASA Technical Reports Server (NTRS)

Lai, Dong; Shapiro, Stuart L.

1995-01-01

We study the secular evolution and gravitational wave signature of a newly formed, rapidly rotating neutron star. The neutron star may arise from core collapse in a massive star or from the accretion-induced collapse of a white dwarf. After a brief dynamical phase, the nascent neutron star settles into an axisymmetric, secularly unstable state. Gravitational radiation drives the star to a nonaxisymmetric, stationary equilibrium configuration via the bar-mode instability. The emitted quasi-periodic gravitational waves have a unique signature: the wave frequency sweeps downward from a few hundred Hertz to zero, while the wave amplitude increase from zero to a maximum and then decays back to zero. Such a wave signal could detected by broadband gravitational wave interferometers currently being constructed. We also characterize two other types of gravitational wave signals that could arise in principle from a rapidly rotating, secularly unstable neutron star: a high-frequency (f greater than or approximately = 1000 Hz) wave which increases the pattern-speed of the star, and a wave that actually increases the angular momentum of the star.

Component-based model to predict aerodynamic noise from high-speed train pantographs

NASA Astrophysics Data System (ADS)

Latorre Iglesias, E.; Thompson, D. J.; Smith, M. G.

2017-04-01

At typical speeds of modern high-speed trains the aerodynamic noise produced by the airflow over the pantograph is a significant source of noise. Although numerical models can be used to predict this they are still very computationally intensive. A semi-empirical component-based prediction model is proposed to predict the aerodynamic noise from train pantographs. The pantograph is approximated as an assembly of cylinders and bars with particular cross-sections. An empirical database is used to obtain the coefficients of the model to account for various factors: incident flow speed, diameter, cross-sectional shape, yaw angle, rounded edges, length-to-width ratio, incoming turbulence and directivity. The overall noise from the pantograph is obtained as the incoherent sum of the predicted noise from the different pantograph struts. The model is validated using available wind tunnel noise measurements of two full-size pantographs. The results show the potential of the semi-empirical model to be used as a rapid tool to predict aerodynamic noise from train pantographs.

Stir bar sorptive extraction of diclofenac from liquid formulations: a proof of concept study.

PubMed

Kole, Prashant Laxman; Millership, Jeff; McElnay, James C

2011-03-25

A new stir bar sorptive extraction (SBSE) technique coupled with HPLC-UV method for quantification of diclofenac in pharmaceutical formulations has been developed and validated as a proof of concept study. Commercially available polydimethylsiloxane stir bars (Twister™) were used for method development and SBSE extraction (pH, phase ratio, stirring speed, temperature, ionic strength and time) and liquid desorption (solvents, desorption method, stirring time etc) procedures were optimised. The method was validated as per ICH guidelines and was successfully applied for the estimation of diclofenac from three liquid formulations viz. Voltarol(®) Optha single dose eye drops, Voltarol(®) Ophtha multidose eye drops and Voltarol(®) ampoules. The developed method was found to be linear (r=0.9999) over 100-2000ng/ml concentration range with acceptable accuracy and precision (tested over three QC concentrations). The SBSE extraction recovery of the diclofenac was found to be 70% and the LOD and LOQ of the validated method were found to be 16.06 and 48.68ng/ml, respectively. Furthermore, a forced degradation study of a diclofenac formulation leading to the formation of structurally similar cyclic impurity (indolinone) was carried out. The developed extraction method showed comparable results to that of the reference method, i.e. method was capable of selectively extracting the indolinone and diclofenac from the liquid matrix. Data on inter and intra stir bar accuracy and precision further confirmed robustness of the method, supporting the multiple re-use of the stir bars. Copyright © 2010 Elsevier B.V. All rights reserved.

Three-dimensional flow in radial turbomachinery and its impact on design

NASA Technical Reports Server (NTRS)

Tan, Choon S.; Hawthorne, William

1993-01-01

In the two papers on the 'Theory of Blade Design for Large Deflections' published in 1984, a new inverse design technique was presented for designing the shape of turbomachinery blades in three-dimensional flow. The technique involves the determination of the blade profile from the specification of a distribution of the product of the radius and the pitched averaged tangential velocity (i.e., r bar-V(sub theta), the mean swirl schedule) within the bladed region. This is in contrast to the conventional inverse design technique for turbomachinery blading in two dimensional flow in which the blade surface pressure or velocity distribution is specified and the blade profile determined as a result; this is feasible in two-dimensional flow because the streamlines along the blade surfaces are known a priori. However, in three-dimensional flow, the stream surface is free to deform within the blade passage so that the streamlines on the blade surfaces are not known a priori; thus it is difficult and not so useful to prescribe the blade surface pressure or velocity distribution and determine the resulting blade profile. It therefore seems logical to prescribe the swirl schedule within the bladed region for designing a turbomachinery blade profile in three-dimensional flow. Furthermore, specifying r bar-V(sub theta) has the following advantages: (1) it is related to the circulation around the blade (i.e., it is an aerodynamic quantity); (2) the work done or extracted is approximately proportional to the overall change in r bar-V(sub theta) across a given blade row (Euler turbine equation); and (3) the rate of change of r bar-V(sub theta) along the mean streamline at the blade is related to the pressure jump across the blade and therefore the blade loading. Since the publications of those two papers, the technique has been applied to the design of a low speed as well as a high speed radial inflow turbine (for turbocharger applications) both of which showed definite improvements in performance over that of wheels of conventional designs, the design study of a high pressure ratio radial inflow turbine with and without splitter blades.

Usability of Three-dimensional Augmented Visual Cues Delivered by Smart Glasses on (Freezing of) Gait in Parkinson's Disease.

PubMed

Janssen, Sabine; Bolte, Benjamin; Nonnekes, Jorik; Bittner, Marian; Bloem, Bastiaan R; Heida, Tjitske; Zhao, Yan; van Wezel, Richard J A

2017-01-01

External cueing is a potentially effective strategy to reduce freezing of gait (FOG) in persons with Parkinson's disease (PD). Case reports suggest that three-dimensional (3D) cues might be more effective in reducing FOG than two-dimensional cues. We investigate the usability of 3D augmented reality visual cues delivered by smart glasses in comparison to conventional 3D transverse bars on the floor and auditory cueing via a metronome in reducing FOG and improving gait parameters. In laboratory experiments, 25 persons with PD and FOG performed walking tasks while wearing custom-made smart glasses under five conditions, at the end-of-dose. For two conditions, augmented visual cues (bars/staircase) were displayed via the smart glasses. The control conditions involved conventional 3D transverse bars on the floor, auditory cueing via a metronome, and no cueing. The number of FOG episodes and percentage of time spent on FOG were rated from video recordings. The stride length and its variability, cycle time and its variability, cadence, and speed were calculated from motion data collected with a motion capture suit equipped with 17 inertial measurement units. A total of 300 FOG episodes occurred in 19 out of 25 participants. There were no statistically significant differences in number of FOG episodes and percentage of time spent on FOG across the five conditions. The conventional bars increased stride length, cycle time, and stride length variability, while decreasing cadence and speed. No effects for the other conditions were found. Participants preferred the metronome most, and the augmented staircase least. They suggested to improve the comfort, esthetics, usability, field of view, and stability of the smart glasses on the head and to reduce their weight and size. In their current form, augmented visual cues delivered by smart glasses are not beneficial for persons with PD and FOG. This could be attributable to distraction, blockage of visual feedback, insufficient familiarization with the smart glasses, or display of the visual cues in the central rather than peripheral visual field. Future smart glasses are required to be more lightweight, comfortable, and user friendly to avoid distraction and blockage of sensory feedback, thus increasing usability.

Gray matter volume covariance patterns associated with gait speed in older adults: a multi-cohort MRI study.

PubMed

Blumen, Helena M; Brown, Lucy L; Habeck, Christian; Allali, Gilles; Ayers, Emmeline; Beauchet, Olivier; Callisaya, Michele; Lipton, Richard B; Mathuranath, P S; Phan, Thanh G; Pradeep Kumar, V G; Srikanth, Velandai; Verghese, Joe

2018-04-09

Accelerated gait decline in aging is associated with many adverse outcomes, including an increased risk for falls, cognitive decline, and dementia. Yet, the brain structures associated with gait speed, and how they relate to specific cognitive domains, are not well-understood. We examined structural brain correlates of gait speed, and how they relate to processing speed, executive function, and episodic memory in three non-demented and community-dwelling older adult cohorts (Overall N = 352), using voxel-based morphometry and multivariate covariance-based statistics. In all three cohorts, we identified gray matter volume covariance patterns associated with gait speed that included brain stem, precuneus, fusiform, motor, supplementary motor, and prefrontal (particularly ventrolateral prefrontal) cortex regions. Greater expression of these gray matter volume covariance patterns linked to gait speed were associated with better processing speed in all three cohorts, and with better executive function in one cohort. These gray matter covariance patterns linked to gait speed were not associated with episodic memory in any of the cohorts. These findings suggest that gait speed, processing speed (and to some extent executive functions) rely on shared neural systems that are subject to age-related and dementia-related change. The implications of these findings are discussed within the context of the development of interventions to compensate for age-related gait and cognitive decline.

Performance evaluation of a 64-slice CT system with z-flying focal spot.

PubMed

Flohr, T; Stierstorfer, K; Raupach, R; Ulzheimer, S; Bruder, H

2004-12-01

The meanwhile established generation of 16-slice CT systems enables routine sub-millimeter imaging at short breath-hold times. Clinical progress in the development of multidetector row CT (MDCT) technology beyond 16 slices can more likely be expected from further improvement in spatial and temporal resolution rather than from a mere increase in the speed of volume coverage. We present an evaluation of a recently introduced 64-slice CT system (SOMATOM Sensation 64, Siemens AG, Forchheim, Germany), which uses a periodic motion of the focal spot in longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices. This technique acquires 64 overlapping 0.6 mm slices per rotation. The sampling scheme corresponds to that of a 64 x 0.3 mm detector, with the goal of improved longitudinal resolution and reduced spiral artifacts. After an introduction to the detector design, we discuss the basics of z-flying focal spot technology (z-Sharp). We present phantom and specimen scans for performance evaluation. The measured full width at half maximum (FWHM) of the thinnest spiral slice is 0.65 mm. All spiral slice widths are almost independent of the pitch, with deviations of less than 0.1 mm from the nominal value. Using a high-resolution bar pattern phantom (CATPHAN, Phantom Laboratories, Salem, NY), the longitudinal resolution can be demonstrated to be up to 15 lp/cm at the isocenter independent of the pitch, corresponding to a bar diameter of 0.33 mm. Longitudinal resolution is only slightly degraded for off-center locations. At a distance of 100 mm from the isocenter, 14 lp/cm can be resolved in the z-direction, corresponding to a bar diameter of 0.36 mm. Spiral "windmill" artifacts presenting as hyper- and hypodense structures around osseous edges are effectively reduced by the z-flying focal spot technique. Cardiac scanning benefits from the short gantry rotation time of 0.33 s, providing up to 83 ms temporal resolution with 2-segment ECG-gated reconstruction.

Dynamics of Gas Near the Galactic Centre

NASA Astrophysics Data System (ADS)

Jenkins, A.; Binney, J.

1994-10-01

We simulate the flow of gas in the Binney et al. model of the bar at the centre of the Milky Way. We argue that the flow of a clumpy interstellar medium is most realistically simulated by a sticky-particle scheme, and investigate two such schemes. In both schemes orbits close to the cusped orbit rapidly become depopulated. This depopulation places a lower limit on the pattern speed since it implies that in the (1, v) plane the cusped orbit lies significantly inside the peak of the Hi terminal-velocity envelope at 1 20. We find that the size of the central molecular disc and the magnitudes of the observed forbidden velocities constrain the eccentricity of the Galactic bar to values similar to that arbitrarily assumed by Binney et al. We study the accretion by the nuclear disc of matter shed by dying bulge stars. We estimate that mass loss by the bulge can replenish the Hi in the nuclear disc within two bar rotation periods, in good agreement with the predictions of the simulations. When accretion of gas from the bulge is included, fine-scale irregular structure persists in the nuclear disc. This structure gives rise to features in longitude-velocity plots which depend significantly on viewing angle, and consequently give rise to asymmetries in longitude. These asymmetries are, however, much less pronounced than those in the observational plots. We conclude that the addition of hydrodynamics to the Binney et al. model does not resolve some important discrepancies between theory and observation. The model's basic idea does, however, have high a priori probability and has enjoyed some significant successes, while a number of potentially important physical processes - most notably the self-gravity of interstellar gas - are neglected in the present simulations. In view of the deficiencies of our simulations and interesting parallels we do observe between simulated and observational longitude-velocity plots, we believe it would be premature to reject the Binney et al. model prior to exploring high-quality three-dimensional simulations that include self-gravitating stars and gas. Key words: accretion, accretion discs - ISM: kinematics and dynamics - ISM: structure -Galaxy: centre - Galaxy: kinematics and dynamics - radio lines: ISM.

Morphodynamic modeling of a large inside sandbar and its dextral morphology in a convergent estuary: Qiantang Estuary, China

NASA Astrophysics Data System (ADS)

Xie, Dongfeng; Gao, Shu; Wang, Zheng Bing; Pan, Cunhong; Wu, Xiuguang; Wang, Qiushun

2017-08-01

We investigate the evolution of a large-scale sand body, a unique type of sandbars in a convergent estuary. Specifically, we analyze and simulate the sand deposition system (defined as an inside bar) in the Qiantang Estuary (QE) in China. The deposit is 130 km long and up to 10 m thick and is characterized by a dextral morphology in the lower QE. Numerical simulation is carried out using an idealized horizontal 2-D morphodynamic model mimicking the present QE settings. Our results indicate that the morphological evolution is controlled by the combination of river discharge and tides. The seasonal and interannual cycles of river discharges play a major role on the inside bar evolution. The bar is eroding during high river discharge periods, but accretion prevails during low river discharge periods. Meanwhile, the highest part of the sand body can move downstream or upstream by several kilometers, modifying the seasonal sediment exchange patterns. We also show that the Coriolis force plays an important role on the dextral morphology patterns in wide, convergent estuaries. It induces a significant lateral water level difference and a large-scale gyre of residual sediment transport. Subsequently, the seaward tail of the inside bar shifts southward to help create a condition for the development of tidal flats in the lower reach of the estuary. The lateral bed level differences induced by Coriolis force are up to several meters. Coriolis effects also modify the behavior of flood and ebb tidal channels.

Location of Instability During a Bench Press Alters Movement Patterns and Electromyographical Activity.

PubMed

Nairn, Brian C; Sutherland, Chad A; Drake, Janessa D M

2015-11-01

Instability training devices with the bench press exercise are becoming increasingly popular. Typically, the instability device is placed at the trunk/upper body (e.g., lying on a Swiss ball); however, a recent product called the Attitube has been developed, which places the location of instability at the hands by users lifting a water-filled tube. Therefore, the purpose of this study was to analyze the effects of different instability devices (location of instability) on kinematic and electromyographical patterns during the bench press exercise. Ten healthy males were recruited and performed 1 set of 3 repetitions for 3 different bench press conditions: Olympic bar on a stable bench (BENCH), Olympic bar on a stability ball (BALL), and Attitube on a stable bench (TUBE). The eccentric and concentric phases were analyzed in 10% intervals while electromyography was recorded from 24 electrode sites, and motion capture was used to track elbow flexion angle and 3-dimensional movement trajectories and vertical velocity of the Bar/Attitube. The prime movers tended to show a reduction in muscle activity during the TUBE trials; however, pectoralis major initially showed increased activation during the eccentric phase of the TUBE condition. The trunk muscle activations were greatest during the TUBE and smallest during the BAR. In addition, the TUBE showed decreased range of elbow flexion and increased medial-lateral movement of the Attitube itself. The results further support the notion that instability devices may be more beneficial for trunk muscles rather than prime movers.

A Modern Picture of Barred Galaxy Dynamics

NASA Astrophysics Data System (ADS)

Petersen, Michael; Weinberg, Martin; Katz, Neal

2018-01-01

Observations of disk galaxies suggest that bars are responsible for altering global galaxy parameters (e.g. structures, gas fraction, star formation rate). The canonical understanding of the mechanisms underpinning bar-driven secular dynamics in disk galaxies has been largely built upon the analysis of linear theory, despite galactic bars being clearly demonstrated to be nonlinear phenomena in n-body simulations. We present simulations of barred Milky Way-like galaxy models designed to elucidate nonlinear barred galaxy dynamics. We have developed two new methodologies for analyzing n-body simulations that give the best of both powerful analytic linear theory and brute force simulation analysis: orbit family identification and multicomponent torque analysis. The software will be offered publicly to the community for their own simulation analysis.The orbit classifier reveals that the details of kinematic components in galactic disks (e.g. the bar, bulge, thin disk, and thick disk components) are powerful discriminators of evolutionary paradigms (i.e. violent instabilities and secular evolution) as well as the basic parameters of the dark matter halo (mass distribution, angular momentum distribution). Multicomponent torque analysis provides a thorough accounting of the transfer of angular momentum between orbits, global patterns, and distinct components in order to better explain the underlying physics which govern the secular evolution of barred disk galaxies.Using these methodologies, we are able to identify the successes and failures of linear theory and traditional n-body simulations en route to a detailed understanding of the control bars exhibit over secular evolution in galaxies. We present explanations for observed physical and velocity structures in observations of barred galaxies alongside predictions for how structures will vary with dynamical properties from galaxy to galaxy as well as over the lifetime of a galaxy, finding that the transfer of angular momentum through previously unidentified channels can more fully explain the observed dynamics.

A morphological novelty for feeding and sound production in the yellowtail clownfish.

PubMed

Olivier, Damien; Frédérich, Bruno; Herrel, Anthony; Parmentier, Eric

2015-04-01

The yellowtail clownfish Amphiprion clarkii is able to close its mouth very quickly by means of the cerato-mandibular (c-md) ligament, a synapomorphic trait of Pomacentridae joining the hyoid bar to the medial part of the lower jaw. This fast closure induces tooth collision, thus producing sounds that the clownfish uses during agonistic behaviors. To investigate whether this rapid jaw movement is also used during feeding, we analyzed the kinematics of sound production and feeding. Sound production, feeding on live planktonic prey, and feeding on food attached to tweezers was filmed with a high-speed camera. Three kinds of kinematic patterns were detected and were associated with the two different types of food presented: one performed to catch planktonic prey (PP), and two (called B-1 and B-2) to bite attached food items. The kinematic pattern of B-2 is similar to that observed during sound production (SP) and the transection of the c-md ligament highlights that sound production and biting-2 motions are dependent on this morphological trait. Our data show that the c-md ligament in addition to its role in sound production allows duplication of the mouth-closing mechanism during feeding. This highlights the key role played by the c-md ligament in sound production and feeding on attached prey. J. Exp. Zool. 323A: 227-238, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

THE HST/ACS COMA CLUSTER SURVEY. VIII. BARRED DISK GALAXIES IN THE CORE OF THE COMA CLUSTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marinova, Irina; Jogee, Shardha; Weinzirl, Tim

2012-02-20

We use high-resolution ({approx}0.''1) F814W Advanced Camera for Surveys (ACS) images from the Hubble Space Telescope ACS Treasury survey of the Coma cluster at z {approx} 0.02 to study bars in massive disk galaxies (S0s), as well as low-mass dwarf galaxies in the core of the Coma cluster, the densest environment in the nearby universe. Our study helps to constrain the evolution of bars and disks in dense environments and provides a comparison point for studies in lower density environments and at higher redshifts. Our results are: (1) we characterize the fraction and properties of bars in a sample ofmore » 32 bright (M{sub V} {approx}< -18, M{sub *} > 10{sup 9.5} M{sub Sun }) S0 galaxies, which dominate the population of massive disk galaxies in the Coma core. We find that the measurement of a bar fraction among S0 galaxies must be handled with special care due to the difficulty in separating unbarred S0s from ellipticals, and the potential dilution of the bar signature by light from a relatively large, bright bulge. The results depend sensitively on the method used: the bar fraction for bright S0s in the Coma core is 50% {+-} 11%, 65% {+-} 11%, and 60% {+-} 11% based on three methods of bar detection, namely, strict ellipse fit criteria, relaxed ellipse fit criteria, and visual classification. (2) We compare the S0 bar fraction across different environments (the Coma core, A901/902, and Virgo) adopting the critical step of using matched samples and matched methods in order to ensure robust comparisons. We find that the bar fraction among bright S0 galaxies does not show a statistically significant variation (within the error bars of {+-}11%) across environments which span two orders of magnitude in galaxy number density (n {approx} 300-10,000 galaxies Mpc{sup -3}) and include rich and poor clusters, such as the core of Coma, the A901/902 cluster, and Virgo. We speculate that the bar fraction among S0s is not significantly enhanced in rich clusters compared to low-density environments for two reasons. First, S0s in rich clusters are less prone to bar instabilities as they are dynamically heated by harassment and are gas poor as a result of ram pressure stripping and accelerated star formation. Second, high-speed encounters in rich clusters may be less effective than slow, strong encounters in inducing bars. (3) We also take advantage of the high resolution of the ACS ({approx}50 pc) to analyze a sample of 333 faint (M{sub V} > -18) dwarf galaxies in the Coma core. Using visual inspection of unsharp-masked images, we find only 13 galaxies with bar and/or spiral structure. An additional eight galaxies show evidence for an inclined disk. The paucity of disk structures in Coma dwarfs suggests that either disks are not common in these galaxies or that any disks present are too hot to develop instabilities.« less

The paradox of extreme high-altitude migration in bar-headed geese Anser indicus

PubMed Central

Hawkes, L. A.; Balachandran, S.; Batbayar, N.; Butler, P. J.; Chua, B.; Douglas, D. C.; Frappell, P. B.; Hou, Y.; Milsom, W. K.; Newman, S. H.; Prosser, D. J.; Sathiyaselvam, P.; Scott, G. R.; Takekawa, J. Y.; Natsagdorj, T.; Wikelski, M.; Witt, M. J.; Yan, B.; Bishop, C. M.

2013-01-01

Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima. PMID:23118436

The paradox of extreme high-altitude migration in bar-headed geese Anser indicus

USGS Publications Warehouse

Hawkes, L.A.; Balachandran, S.; Batbayar, N.; Butler, P.J.; Chua, B.; Douglas, David C.; Frappell, P.B.; Hou, Y.; Milsom, W.K.; Newman, S.H.; Prosser, D.J.; Sathiyaselvam, P.; Scott, G.R.; Takekawa, John Y.; Natsagdorj, T.; Wikelski, M.; Witt, M.J.; Yan, B.; Bishop, C.M.

2012-01-01

Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima.

Grid-Optimization Program for Photovoltaic Cells

NASA Technical Reports Server (NTRS)

Daniel, R. E.; Lee, T. S.

1986-01-01

CELLOPT program developed to assist in designing grid pattern of current-conducting material on photovoltaic cell. Analyzes parasitic resistance losses and shadow loss associated with metallized grid pattern on both round and rectangular solar cells. Though performs sensitivity studies, used primarily to optimize grid design in terms of bus bar and grid lines by minimizing power loss. CELLOPT written in APL.

Effect of pencil grasp on the speed and legibility of handwriting in children.

PubMed

Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl; Chau, Tom

2012-01-01

Pencil grasps other than the dynamic tripod may be functional for handwriting. This study examined the impact of grasp on handwriting speed and legibility. We videotaped 120 typically developing fourth-grade students while they performed a writing task. We categorized the grasps they used and evaluated their writing for speed and legibility using a handwriting assessment. Using linear regression analysis, we examined the relationship between grasp and handwriting. We documented six categories of pencil grasp: four mature grasp patterns, one immature grasp pattern, and one alternating grasp pattern. Multiple linear regression results revealed no significant effect for mature grasp on either legibility or speed. Pencil grasp patterns did not influence handwriting speed or legibility in this sample of typically developing children. This finding adds to the mounting body of evidence that alternative grasps may be acceptable for fast and legible handwriting. Copyright © 2012 by the American Occupational Therapy Association, Inc.

A Comparison of Sleep and Performance of Sailors on an Operationally Deployed U.S. Navy Warship

DTIC Science & Technology

2013-09-01

The crew’s mission on a deployed warship is inherently dangerous. The nature of the job means navigating restricted waters, conducting underway...The nature of the job means navigating restricted waters, conducting underway replenishments with less than 200 feet of lateral separation from... concentration equivalent. Error bars ± s.e. (From Dawson & Reid, 1997). .............................9 Figure 4. Mean psychomotor vigilance task speed (and

System Engineering Analysis of Topside Cranes Installed on AD, AR, and AS Class Ships

DTIC Science & Technology

1982-02-06

4 severity CASREPs. Water or moisture in oumzs or motors accounted for five CASREPs; moisture in a transformer caused a class C fire , which resulted...Components of Bridge Cranes, Monorail Hoist Systems, and Side Port Hoists Associated Equipment: Accumulators Ladders Speed reducers Brakes Load blocks...Switches Bridge Locking devices *Tow bars Bumpers * Monorails Tracks Collector assembly Motors (electrical *Trolley buses Controller and hydraulic) *Trolleys

Abstracts. 1978 AFOSR Contractors Meeting on Air-Breathing Combustion Dynamics and Kinetics, Ramada Inn-Downtown Dayton, Ohio, 10 - 13 October 1978

DTIC Science & Technology

1978-10-13

Combustion in G.D. Smith, C.E. Peters High Speed Flows AEDC/ARO (PO-78-0012) 5:00 ADJOURN 6:30 Social Hour (Cash Bar) Ramada Inn Banquet 12 Oct. 78...which would sustain the instability structures observed in a number of problemA . During the initial phase of the development of the instabilities, the

Reservoir sedimentology of the Big Injun sandstone in Granny Creek field, West Virginia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Xiangdong; Donaldson, K.; Donaldson, A.C.

1992-01-01

Big Injun sandstones of Granny Creek oil field (WV) are interpreted as fluvial-deltaic deposits from core and geophysical log data. The reservoir consists of two distinctive lithologies throughout the field; fine-grained sandstones overlain by pebbly and coarse-grained sandstones. Lower fine-grained sandstones were deposited in westward prograding river-mouth bars, where distal, marine-dominant proximal, and fluvial-dominant proximal bar subfacies are recognized. Principal pay is marine-influenced proximal bar, where porosity ranges from 13 to 23% and permeability, up to 24 md. Thin marine transgressive shales and their laterally equivalent low-permeability sandstones bound time-rock sequences generally less than 10 meters thick. Where field mapped,more » width of prograding bar sequence is approximately 2.7 km (dip trend), measured from truncated eastern edge (pre-coarse-grained member erosional surface) to distal western margin. Dip-trending elongate lobes occur within marine-influenced proximal mouth-bar area, representing thickest part of tidally influenced preserved bar. Upper coarse-grained part of reservoir consists of pebbly sandstones of channel fill from bedload streams. Laterally persistent low permeability cemented interval in lower part commonly caps underlying pay zone and probably serves as seal to vertical oil migration. Southwest paleoflow trends based on thickness maps of unit portent emergence of West Virginia dome, which influences erosion patterns of pre-Greenbrier unconformity for this combination oil trap.« less

A two degrees-of-freedom piezoelectric single-crystal micromotor

NASA Astrophysics Data System (ADS)

Chen, Zhijiang; Li, Xiaotian; Liu, Guoxi; Dong, Shuxiang

2014-12-01

A two degrees-of-freedom (DOF) ultrasonic micromotor made of piezoelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystal square-bar (dimensions 2 × 2 × 9 mm3) was developed. The PIN-PMN-PT square-bar stator can generate standing wave elliptical motions in two orthogonal vertical planes by combining the first longitudinal and second bending vibration modes, enabling it to drive a slider in two orthogonal directions. The relatively large driving forces of 0.25 N and motion speed of 35 mm/s were obtained under a voltage of 80 Vpp at its resonance frequency of 87.5 kHz. The proposed micromotor has potential for applications in micro robots, cell manipulators, and digital cameras as a two-DOF actuator.

STUDY OF REUSABLE PHOTOSENSITIVE ELECTRON RECORDING MEDIA

DTIC Science & Technology

a low molecular weight polystyrene resin (Dow Ps-2) is most suitable. The first photodielectrically deformed picture of a course bar pattern is reported using CdSe:Cu powder dispersed in carnauba wax . (Author)

Effects of Gravel Bars on Nutrient Spiraling in Bedrock-Alluvium Streams

NASA Astrophysics Data System (ADS)

Iobst, B. R.; Carroll, E. P.; Furbish, D. J.

2007-05-01

The importance of the connection between nutrient transport and local stream geomorphology is becoming increasingly important. Studies have shown that the interconnectivity of nutrient cycles in the downstream direction is in part controlled by the distribution and size of gravel bars in low order streams, as hyporheic flow occurs dominantly through alternate and mid-channel gravel bars. For this investigation multiple gravel bars in a 3rd order bedrock-alluvium stream were studied to determine general relationships between nutrient spiraling and hyporheic flow. The first goal was to understand (1) the extent to which water moves through hyporheic zones and (2) the basic chemistry of the hyporheic water. The second part of the study was to understand how nutrients, notably nitrogen, are affected in their cycling by the relatively long residence times encountered in gravel bars during hyporheic flow. Wells were installed along a 600 m reach of Panther Creek, KY in selected bars, as well as in a secondary location involving a grid installation pattern in one large bar. Results have shown that hyporheic flow through gravel bars is an important factor in influencing stream chemistry. Background water chemistry surveys have shown that certain parameters, specifically ammonium and nitrogen concentrations vary downstream, and that the dominant control over these changes is gravel bar location. Rhodamine WT was used in field tracer tests to track the travel times of water through bars as well as partitioning of water between the open channel and hyporheic flows. Further tests will be conducted utilizing a stable isotope study to determine how nitrogen is affected by hyporheic flow, and what implications this has for nutrient transport. We expect results to show that the spacing and size of gravel bars is a dominant control in key nutrient spiraling parameters, namely uptake lengths and overall nitrogen cycling rates. This has implications for how natural systems will respond to human impacts, both through the modification of the physical template of stream systems as well as increased anthropogenic loading of nitrogen.

Substorm-associated radar auroral surges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, M.P.; Southwood, D.J.; Lester, M.

The authors report a recurrent convection signature observed in the E region ionosphere within {approximately}2 hours of the dusk meridian by the SABRE radar facility. In a typical event, the irregularity drift speed in the SABRE field of view is seen to increase from about 300 m s{sup {minus}1} to of the order of 1 km s{sup {minus}1} in the space of about 10 min. The speed subsequently remains at the enhanced level for 10 min or longer before declining as rapidly as its onset. The total event duration ranges between 30 min and 1 hour. As the irregularity driftmore » speed increases the direction of the drift velocity changes, rotating poleward. At the same time, the radar backscatter power decreases. The onset of the drift speed enhancement crosses the SABRE field of view as a front moving from east to west. Detailed study of individual events indicates that the events are associated with increases in the {vert bar}AL{vert bar} index and with the injection of energetic particles into geosynchronous orbit. The authors thus suggest that the events are a part of the magnetospheric response to the onset of a geomagnetic substorm. However, while each event appears to be associated with a substorm onset, not every substorm onset is associated with an event, at least not at SABRE. They estimate the speed at which the substorm-initiated ionospheric flow enhancement moves from the nightside to be 1-4 km s{sup {minus}1}, a figure that is consistent with the rate at which the drift velocity front crosses the SABRE field of view. Although the front is associated with a rotation in the drift velocity, they see little evidence of strong vertical vorticity as the front passes. However, shears in the flow do develop subsequently which seem likely to correspond to field-aligned current. Although associated with substorm onset, they argue that these events are distinct from westward traveling surges and appear to differ from the midlatitude phenomenon known as subauroral ion drifts.« less

Effect of E85 on RCCI Performance and Emissions on a Multi-Cylinder Light-Duty Diesel Engine - SAE World Congress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curran, Scott; Hanson, Reed M; Wagner, Robert M

2012-01-01

This paper investigates the effect of E85 on load expansion and FTP modal point emissions indices under reactivity controlled compression ignition (RCCI) operation on a light-duty multi-cylinder diesel engine. A General Motors (GM) 1.9L four-cylinder diesel engine with the stock compression ratio of 17.5:1, common rail diesel injection system, high-pressure exhaust gas recirculation (EGR) system and variable geometry turbocharger was modified to allow for port fuel injection with gasoline or E85. Controlling the fuel reactivity in-cylinder by the adjustment of the ratio of premixed low-reactivity fuel (gasoline or E85) to direct injected high reactivity fuel (diesel fuel) has been shownmore » to extend the operating range of high-efficiency clean combustion (HECC) compared to the use of a single fuel alone as in homogeneous charge compression ignition (HCCI) or premixed charge compression ignition (PCCI). The effect of E85 on the Ad-hoc federal test procedure (FTP) modal points is explored along with the effect of load expansion through the light-duty diesel speed operating range. The Ad-hoc FTP modal points of 1500 rpm, 1.0bar brake mean effective pressure (BMEP); 1500rpm, 2.6bar BMEP; 2000rpm, 2.0bar BMEP; 2300rpm, 4.2bar BMEP; and 2600rpm, 8.8bar BMEP were explored. Previous results with 96 RON unleaded test gasoline (UTG-96) and ultra-low sulfur diesel (ULSD) showed that with stock hardware, the 2600rpm, 8.8bar BMEP modal point was not obtainable due to excessive cylinder pressure rise rate and unstable combustion both with and without the use of EGR. Brake thermal efficiency and emissions performance of RCCI operation with E85 and ULSD is explored and compared against conventional diesel combustion (CDC) and RCCI operation with UTG 96 and ULSD.« less

The use of water-jetting technology in prostheses revision surgery-first results of parameter studies on bone and bone cement.

PubMed

Honl, M; Rentzsch, R; Müller, G; Brandt, C; Bluhm, A; Hille, E; Louis, H; Morlock, M

2000-01-01

Water-jet cutting techniques have been used in industrial applications for many different materials. Recently these techniques have been developed into a revolutionary cutting tool for soft tissues in visceral surgery. The present study investigates the usage of this cutting technology for the revision surgery of endoprostheses. In the first part of the study, samples of bovine bone and acrylic bone cement (PMMA) were cut using an industrial jet cutting device with pure water. Below 400 bar, only PMMA was cut; above 400 bar, bone was also cut, but only pressures above 800 bar resulted in clinically useful rates of material removal (cut depth 2. 4 mm at 10 mm/min traverse speed). In the second part of the study, the effect of adding biocompatible abrasives to the water in order to reduce the required pressure was investigated, resulting in a significantly higher removal of material. At 600 bar, PMMA was cut 5. 2 mm deep with plain water and 15.2 mm deep with added abrasives. The quality of the cuts was increased by the abrasive. Though there was no clear selectivity between bone and PMMA any more, the rate of material removal at similar pressures was significantly higher for PMMA than for bone (600 bar: 1.6 mm cut depth for bone samples, 15.2 mm for PMMA). The measured cut depths with either method were not influenced by a change of the cutting direction with respect to the main direction of the osteons in the bone. However, a reduction of the jet surface angle (90 degrees to 23 degrees ) resulted for bone in a significantly lower cut depth at 600 bar (plain water: 0.62 mm vs. 0.06 mm; abrasive: 1.61 mm vs. 0.60 mm). The laboratory experiments indicate that abrasive water jets may be suitable for cutting biomaterials like bone and bone cement. Copyright 2000 John Wiley & Sons, Inc.

Large-scale laboratory study of breaking wave hydrodynamics over a fixed bar

NASA Astrophysics Data System (ADS)

van der A, Dominic A.; van der Zanden, Joep; O'Donoghue, Tom; Hurther, David; Cáceres, Iván.; McLelland, Stuart J.; Ribberink, Jan S.

2017-04-01

A large-scale wave flume experiment has been carried out involving a T = 4 s regular wave with H = 0.85 m wave height plunging over a fixed barred beach profile. Velocity profiles were measured at 12 locations along the breaker bar using LDA and ADV. A strong undertow is generated reaching magnitudes of 0.8 m/s on the shoreward side of the breaker bar. A circulation pattern occurs between the breaking area and the inner surf zone. Time-averaged turbulent kinetic energy (TKE) is largest in the breaking area on the shoreward side of the bar where the plunging jet penetrates the water column. At this location, and on the bar crest, TKE generated at the water surface in the breaking process reaches the bottom boundary layer. In the breaking area, TKE does not reduce to zero within a wave cycle which leads to a high level of "residual" turbulence and therefore lower temporal variation in TKE compared to previous studies of breaking waves on plane beach slopes. It is argued that this residual turbulence results from the breaker bar-trough geometry, which enables larger length scales and time scales of breaking-generated vortices and which enhances turbulence production within the water column compared to plane beaches. Transport of TKE is dominated by the undertow-related flux, whereas the wave-related and turbulent fluxes are approximately an order of magnitude smaller. Turbulence production and dissipation are largest in the breaker zone and of similar magnitude, but in the shoaling zone and inner surf zone production is negligible and dissipation dominates.

Finding minimum-quotient cuts in planar graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.K.; Phillips, C.A.

Given a graph G = (V, E) where each vertex v {element_of} V is assigned a weight w(v) and each edge e {element_of} E is assigned a cost c(e), the quotient of a cut partitioning the vertices of V into sets S and {bar S} is c(S, {bar S})/min{l_brace}w(S), w(S){r_brace}, where c(S, {bar S}) is the sum of the costs of the edges crossing the cut and w(S) and w({bar S}) are the sum of the weights of the vertices in S and {bar S}, respectively. The problem of finding a cut whose quotient is minimum for a graph hasmore » in recent years attracted considerable attention, due in large part to the work of Rao and Leighton and Rao. They have shown that an algorithm (exact or approximation) for the minimum-quotient-cut problem can be used to obtain an approximation algorithm for the more famous minimumb-balanced-cut problem, which requires finding a cut (S,{bar S}) minimizing c(S,{bar S}) subject to the constraint bW {le} w(S) {le} (1 {minus} b)W, where W is the total vertex weight and b is some fixed balance in the range 0 < b {le} {1/2}. Unfortunately, the minimum-quotient-cut problem is strongly NP-hard for general graphs, and the best polynomial-time approximation algorithm known for the general problem guarantees only a cut whose quotient is at mostO(lg n) times optimal, where n is the size of the graph. However, for planar graphs, the minimum-quotient-cut problem appears more tractable, as Rao has developed several efficient approximation algorithms for the planar version of the problem capable of finding a cut whose quotient is at most some constant times optimal. In this paper, we improve Rao`s algorithms, both in terms of accuracy and speed. As our first result, we present two pseudopolynomial-time exact algorithms for the planar minimum-quotient-cut problem. As Rao`s most accurate approximation algorithm for the problem -- also a pseudopolynomial-time algorithm -- guarantees only a 1.5-times-optimal cut, our algorithms represent a significant advance.« less

Finding minimum-quotient cuts in planar graphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, J.K.; Phillips, C.A.

Given a graph G = (V, E) where each vertex v [element of] V is assigned a weight w(v) and each edge e [element of] E is assigned a cost c(e), the quotient of a cut partitioning the vertices of V into sets S and [bar S] is c(S, [bar S])/min[l brace]w(S), w(S)[r brace], where c(S, [bar S]) is the sum of the costs of the edges crossing the cut and w(S) and w([bar S]) are the sum of the weights of the vertices in S and [bar S], respectively. The problem of finding a cut whose quotient is minimummore » for a graph has in recent years attracted considerable attention, due in large part to the work of Rao and Leighton and Rao. They have shown that an algorithm (exact or approximation) for the minimum-quotient-cut problem can be used to obtain an approximation algorithm for the more famous minimumb-balanced-cut problem, which requires finding a cut (S,[bar S]) minimizing c(S,[bar S]) subject to the constraint bW [le] w(S) [le] (1 [minus] b)W, where W is the total vertex weight and b is some fixed balance in the range 0 < b [le] [1/2]. Unfortunately, the minimum-quotient-cut problem is strongly NP-hard for general graphs, and the best polynomial-time approximation algorithm known for the general problem guarantees only a cut whose quotient is at mostO(lg n) times optimal, where n is the size of the graph. However, for planar graphs, the minimum-quotient-cut problem appears more tractable, as Rao has developed several efficient approximation algorithms for the planar version of the problem capable of finding a cut whose quotient is at most some constant times optimal. In this paper, we improve Rao's algorithms, both in terms of accuracy and speed. As our first result, we present two pseudopolynomial-time exact algorithms for the planar minimum-quotient-cut problem. As Rao's most accurate approximation algorithm for the problem -- also a pseudopolynomial-time algorithm -- guarantees only a 1.5-times-optimal cut, our algorithms represent a significant advance.« less

The punctum fixum-punctum mobile model: a neuromuscular principle for efficient movement generation?

PubMed

von Laßberg, Christoph; Rapp, Walter

2015-01-01

According to the "punctum fixum-punctum mobile model" that was introduced in prior studies, for generation of the most effective intentional acceleration of a body part the intersegmental neuromuscular onset succession has to spread successively from the rotation axis (punctum fixum) toward the body part that shall be accelerated (punctum mobile). The aim of the present study was to investigate whether this principle is, indeed, fundamental for any kind of efficient rotational accelerations in general, independent of the kind of movements, type of rotational axis, the current body position, or movement direction. Neuromuscular onset succession was captured by surface electromyography of relevant muscles of the anterior and posterior muscle chain in 16 high-level gymnasts during intentional accelerating movement phases while performing 18 different gymnastics elements (in various body positions to forward and backward, performed on high bar, parallel bars, rings and trampoline), as well as during non-sport specific pivot movements around the longitudinal axis. The succession patterns to generate the acceleration phases during these movements were described and statistically evaluated based on the onset time difference between the muscles of the corresponding muscle chain. In all the analyzed movement phases, the results clearly support the hypothesized succession pattern from punctum fixum to punctum mobile. This principle was further underlined by the finding that the succession patterns do change their direction running through the body when the rotational axis (punctum fixum) has been changed (e.g., high bar or rings [hands] vs. floor or trampoline [feet]). The findings improve our understanding of intersegmental neuromuscular coordination patterns to generate intentional movements most efficiently. This could help to develop more specific methods to facilitate such patterns in particular contexts, thus allowing for shorter motor learning procedures of context-specific key movement sequences in different disciplines of sports, as well as during non-sport specific movements.

The Punctum Fixum-Punctum Mobile Model: A Neuromuscular Principle for Efficient Movement Generation?

PubMed Central

von Laßberg, Christoph; Rapp, Walter

2015-01-01

According to the “punctum fixum–punctum mobile model” that was introduced in prior studies, for generation of the most effective intentional acceleration of a body part the intersegmental neuromuscular onset succession has to spread successively from the rotation axis (punctum fixum) toward the body part that shall be accelerated (punctum mobile). The aim of the present study was to investigate whether this principle is, indeed, fundamental for any kind of efficient rotational accelerations in general, independent of the kind of movements, type of rotational axis, the current body position, or movement direction. Neuromuscular onset succession was captured by surface electromyography of relevant muscles of the anterior and posterior muscle chain in 16 high-level gymnasts during intentional accelerating movement phases while performing 18 different gymnastics elements (in various body positions to forward and backward, performed on high bar, parallel bars, rings and trampoline), as well as during non-sport specific pivot movements around the longitudinal axis. The succession patterns to generate the acceleration phases during these movements were described and statistically evaluated based on the onset time difference between the muscles of the corresponding muscle chain. In all the analyzed movement phases, the results clearly support the hypothesized succession pattern from punctum fixum to punctum mobile. This principle was further underlined by the finding that the succession patterns do change their direction running through the body when the rotational axis (punctum fixum) has been changed (e.g., high bar or rings [hands] vs. floor or trampoline [feet]). The findings improve our understanding of intersegmental neuromuscular coordination patterns to generate intentional movements most efficiently. This could help to develop more specific methods to facilitate such patterns in particular contexts, thus allowing for shorter motor learning procedures of context-specific key movement sequences in different disciplines of sports, as well as during non-sport specific movements. PMID:25822498

Dazzle camouflage and the confusion effect: the influence of varying speed on target tracking.

PubMed

Hogan, Benedict G; Cuthill, Innes C; Scott-Samuel, Nicholas E

2017-01-01

The formation of groups is a common strategy to avoid predation in animals, and recent research has indicated that there may be interactions between some forms of defensive coloration, notably high-contrast 'dazzle camouflage', and one of the proposed benefits of grouping: the confusion effect. However, research into the benefits of dazzle camouflage has largely used targets moving with constant speed. This simplification may not generalize well to real animal systems, where a number of factors influence both within- and between-individual variation in speed. Departure from the speed of your neighbours in a group may be predicted to undermine the confusion effect. This is because individual speed may become a parameter through which the observer can individuate otherwise similar targets: an 'oddity effect'. However, dazzle camouflage patterns are thought to interfere with predator perception of speed and trajectory. The current experiment investigated the possibility that such patterns could ameliorate the oddity effect caused by within-group differences in prey speed. We found that variation in speed increased the ease with which participants could track targets in all conditions. However, we found no evidence that motion dazzle camouflage patterns reduced oddity effects based on this variation in speed, a result that may be informative about the mechanisms behind this form of defensive coloration. In addition, results from those conditions most similar to those of published studies replicated previous results, indicating that targets with stripes parallel to the direction of motion are harder to track, and that this pattern interacts with the confusion effect to a greater degree than background matching or orthogonal-to-motion striped patterns.

Fidelity of the ensemble code for visual motion in primate retina.

PubMed

Frechette, E S; Sher, A; Grivich, M I; Petrusca, D; Litke, A M; Chichilnisky, E J

2005-07-01

Sensory experience typically depends on the ensemble activity of hundreds or thousands of neurons, but little is known about how populations of neurons faithfully encode behaviorally important sensory information. We examined how precisely speed of movement is encoded in the population activity of magnocellular-projecting parasol retinal ganglion cells (RGCs) in macaque monkey retina. Multi-electrode recordings were used to measure the activity of approximately 100 parasol RGCs simultaneously in isolated retinas stimulated with moving bars. To examine how faithfully the retina signals motion, stimulus speed was estimated directly from recorded RGC responses using an optimized algorithm that resembles models of motion sensing in the brain. RGC population activity encoded speed with a precision of approximately 1%. The elementary motion signal was conveyed in approximately 10 ms, comparable to the interspike interval. Temporal structure in spike trains provided more precise speed estimates than time-varying firing rates. Correlated activity between RGCs had little effect on speed estimates. The spatial dispersion of RGC receptive fields along the axis of motion influenced speed estimates more strongly than along the orthogonal direction, as predicted by a simple model based on RGC response time variability and optimal pooling. on and off cells encoded speed with similar and statistically independent variability. Simulation of downstream speed estimation using populations of speed-tuned units showed that peak (winner take all) readout provided more precise speed estimates than centroid (vector average) readout. These findings reveal how faithfully the retinal population code conveys information about stimulus speed and the consequences for motion sensing in the brain.

High-performance silicon photonic tri-state switch based on balanced nested Mach-Zehnder interferometer.

PubMed

Lu, Zeqin; Celo, Dritan; Mehrvar, Hamid; Bernier, Eric; Chrostowski, Lukas

2017-09-25

This work proposes a novel silicon photonic tri-state (cross/bar/blocking) switch, featuring high-speed switching, broadband operation, and crosstalk-free performance. The switch is designed based on a 2 × 2 balanced nested Mach-Zehnder interferometer structure with carrier injection phase tuning. As compared to silicon photonic dual-state (cross/bar) switches based on Mach-Zehnder interferometers with carrier injection phase tuning, the proposed switch not only has better performance in cross/bar switching but also provides an extra blocking state. The unique blocking state has a great advantage in applications of N × N switch fabrics, where idle switching elements in the fabrics can be configured to the blocking state for crosstalk suppression. According to our numerical experiments on a fully loaded 8 × 8 dilated Banyan switch fabric, the worst output crosstalk of the 8 × 8 switch can be dramatically suppressed by more than 50 dB, by assigning the blocking state to idle switching elements in the fabric. The results of this work can extend the functionality of silicon photonic switches and significantly improve the performance of on-chip N × N photonic switching technologies.

Optimization of vehicle-trailer connection systems

NASA Astrophysics Data System (ADS)

Sorge, F.

2016-09-01

The three main requirements of a vehicle-trailer connection system are: en route stability, over- or under-steering restraint, minimum off-tracking along curved path. Linking the two units by four-bar trapeziums, wider stability margins may be attained in comparison with the conventional pintle-hitch for both instability types, divergent or oscillating. The stability maps are traced applying the Hurwitz method or the direct analysis of the characteristic equation at the instability threshold. Several types of four-bar linkages may be quickly tested, with the drawbars converging towards the trailer or the towing unit. The latter configuration appears preferable in terms of self-stability and may yield high critical speeds by optimising the geometrical and physical properties. Nevertheless, the system stability may be improved in general by additional vibration dampers in parallel with the connection linkage. Moreover, the four-bar connection may produce significant corrections of the under-steering or over-steering behaviour of the vehicle-train after a steering command from the driver. The off- tracking along the curved paths may be also optimized or kept inside prefixed margins of acceptableness. Activating electronic stability systems if necessary, fair results are obtainable for both the steering conduct and the off-tracking.

Population responses in V1 encode different figures by response amplitude.

PubMed

Gilad, Ariel; Slovin, Hamutal

2015-04-22

The visual system simultaneously segregates between several objects presented in a visual scene. The neural code for encoding different objects or figures is not well understood. To study this question, we trained two monkeys to discriminate whether two elongated bars are either separate, thus generating two different figures, or connected, thus generating a single figure. Using voltage-sensitive dyes, we imaged at high spatial and temporal resolution V1 population responses evoked by the two bars, while keeping their local attributes similar among the two conditions. In the separate condition, unlike the connected condition, the population response to one bar is enhanced, whereas the response to the other is simultaneously suppressed. The response to the background remained unchanged between the two conditions. This divergent pattern developed ∼200 ms poststimulus onset and could discriminate well between the separate and connected single trials. The stimulus separation saliency and behavioral report were highly correlated with the differential response to the bars. In addition, the proximity and/or the specific location of the connectors seemed to have only a weak effect on this late activity pattern, further supporting the involvement of top-down influences. Additional neural codes were less informative about the separate and connected conditions, with much less consistency and discriminability compared with a response amplitude code. We suggest that V1 is involved in the encoding of each figure by different neuronal response amplitude, which can mediate their segregation and perception. Copyright © 2015 the authors 0270-6474/15/356335-15$15.00/0.

Exploring microwave resonant multi-point ignition using high-speed schlieren imaging

NASA Astrophysics Data System (ADS)

Liu, Cheng; Zhang, Guixin; Xie, Hong; Deng, Lei; Wang, Zhi

2018-03-01

Microwave plasma offers a potential method to achieve rapid combustion in a high-speed combustor. In this paper, microwave resonant multi-point ignition and its control method have been studied via high-speed schlieren imaging. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. The microwave pulse in 2.45 GHz with 2 ms width and 3 kW peak power was employed as an ignition energy source to produce initial flame kernels in the combustion chamber. A reflective schlieren method was designed to illustrate the flame development process with a high-speed camera. The bottom of the combustion chamber was made of a quartz glass coated with indium tin oxide, which ensures sufficient microwave reflection and light penetration. Ignition experiments were conducted at 2 bars of stoichiometric methane-air mixtures. Schlieren images show that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in different flame kernels. Ignition kernels were discussed in three types according to their appearances. Pressure curves and combustion duration also show that multi-point ignition plays a significant role in accelerating combustion.

Exploring microwave resonant multi-point ignition using high-speed schlieren imaging.

PubMed

Liu, Cheng; Zhang, Guixin; Xie, Hong; Deng, Lei; Wang, Zhi

2018-03-01

Microwave plasma offers a potential method to achieve rapid combustion in a high-speed combustor. In this paper, microwave resonant multi-point ignition and its control method have been studied via high-speed schlieren imaging. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. The microwave pulse in 2.45 GHz with 2 ms width and 3 kW peak power was employed as an ignition energy source to produce initial flame kernels in the combustion chamber. A reflective schlieren method was designed to illustrate the flame development process with a high-speed camera. The bottom of the combustion chamber was made of a quartz glass coated with indium tin oxide, which ensures sufficient microwave reflection and light penetration. Ignition experiments were conducted at 2 bars of stoichiometric methane-air mixtures. Schlieren images show that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in different flame kernels. Ignition kernels were discussed in three types according to their appearances. Pressure curves and combustion duration also show that multi-point ignition plays a significant role in accelerating combustion.

Movement patterns of Bar-headed Geese Anser indicus during breeding and post-breeding periods at Qinghai Lake, China

USGS Publications Warehouse

Cui, Peng; Hou, Yuansheng; Tang, Mingjie; Zhang, Haiting; Zuohua, Yuanchun; Yin, Zuohua; Li, Tianxian; Guo, Shan; Xing, Zhi; He, Yubang; Prosser, Diann J.; Newman, Scott H.; Takekawa, John Y.; Yan, Baoping; Lei, Fumin

2011-01-01

The highly pathogenic avian influenza (HPAI) H5N1 outbreak at Qinghai Lake, China, in 2005 caused the death of over 6,000 migratory birds, half of which were Bar-headed Geese Anser indicus. Understanding the movements of this species may inform monitoring of outbreak risks for HPAI viruses; thus, we investigated the movement patterns of 29 Bar-headed Geese at Qinghai Lake, China during 2007 and 2008 by using high resolution GPS satellite telemetry. We described the movements and distribution of marked Bar-headed Geese during the pre-nesting, nesting, and moulting periods. Of 21 Bar-headed Geese with complete transmission records, 3 moved to other areas during the nesting period: 2 to Jianghe wetland (50 km northwest of Qinghai Lake) and 1 to Cuolongka Lake (220 km northwest of Qinghai Lake) during the nesting period. We identified nesting attempts of 7 of the marked geese at Qinghai Lake. Four completed successful nesting attempts according to our rules of judgment for the breeding status, and 2 geese lost broods soon after hatching (hereafter referred to as unsuccessful breeders). Of 18 geese present at Qinghai Lake during the nesting period, 9 (6 non-breeders, 2 successful breeders and 1 unsuccessful breeder) remained at Qinghai Lake during the moulting period; and 9 (5 non-breeders, 4 unsuccessful breeders) left Qinghai Lake for moulting. Kuhai Lake, Donggeicuona Lake, Alake Lake, Zhaling-Eling Lake area and Huangheyuan wetland area were used as moulting sites. Geese that moulted at Qinghai Lake, Cuolongka Lake, Kuhai Lake, Donggeicuona Lake and Alake Lake also moved to Zhaling-Eling Lake area or Huangheyuan wetland area and stayed there for several days prior to autumn migration. Mean home range and core area estimates did not differ significantly by sex, year and between breeders and non-breeders.

Geographic variation in Bar-headed geese Anser indicus: connectivity of wintering and breeding grounds across a broad front

USGS Publications Warehouse

Takekawa, John Y.; Heath, Shane R.; Douglas, David C.; Perry, William M.; Javed, Sàlim; Newman, Scott H.; Suwal, Rajendra N.; Rahman, Asad R.; Choudhury, Binod C.; Prosser, Diann J.; Yan, Baoping; Hou, Yuansheng; Batbayar, Nyambayar; Natsagdorj, Tseveenmayadag; Bishop, Charles M.; Butler, Patrick J.; Frappell, Peter B.; Milsom, William K.; Scott, Graham R.; Hawkes, Lucy A.; Wikelski, Martin

2009-01-01

The connectivity and frequency of exchange between sub-populations of migratory birds is integral to understanding population dynamics over the entire species' range. True geese are highly philopatric and acquire lifetime mates during the winter, suggesting that the number of distinct sub-populations may be related to the number of distinct wintering areas. In the Bar-headed Goose Anser indicus, a species found exclusively in Central Asia, the connectivity between breeding and wintering areas is not well known. Their migration includes crossing a broad front of the Himalaya Cordillera, a significant barrier to migration for most birds. Many Bar-headed Geese fly to breeding areas on the Tibetan-Qinghai Plateau (TQP), the highest plateau in the world. From 2005-2008, 60 Bar-headed Geese were captured and marked with satellite transmitters in Nepal (n = 2), India (n = 6), China (n = 29), and Mongolia (n = 23) to examine their migration and distribution. Distinct differences were observed in their migration corridors and timing of movements, including an apparent leap-frog migration pattern for geese from Mongolia. Measurements of geese from Mongolia were larger than their counterparts from China, providing some evidence of morphological differences. Alteration of habitats in China, including the warming effects of climate change on glaciers increasing runoff to TQP wetlands, may be changing goose migration patterns and timing. With the exception of one individual, all geese from Qinghai Lake, China wintered in the southern TQP near Lhasa, and their increasing numbers in that region may be related to the effects of climate change and agricultural development. Thus, our findings document both morphological and geographical variation in sub-populations of Bar-headed Geese, but their resilience to environmental change may be lost if migratory short-stopping results in larger congregations restricted to a smaller number of wintering areas.

Movement patterns of Bar-headed Geese Anser indicus during breeding and post-breeding periods at Qinghai Lake, China

USGS Publications Warehouse

Cui, P.; Hou, Y.; Tang, M.; Zhang, H.; Zhou, Y.; Yin, Z.; Li, T.; Guo, S.; Xing, Z.; He, Y.; Prosser, D.J.; Newman, S.H.; Takekawa, John Y.; Yan, B.; Lei, F.

2011-01-01

The highly pathogenic avian influenza (HPAI) H5N1 outbreak at Qinghai Lake, China, in 2005 caused the death of over 6,000 migratory birds, half of which were Bar-headed Geese Anser indicus. Understanding the movements of this species may inform monitoring of outbreak risks for HPAI viruses; thus, we investigated the movement patterns of 29 Bar-headed Geese at Qinghai Lake, China during 2007 and 2008 by using high resolution GPS satellite telemetry. We described the movements and distribution of marked Bar-headed Geese during the pre-nesting, nesting, and moulting periods. Of 21 Bar-headed Geese with complete transmission records, 3 moved to other areas during the nesting period: 2 to Jianghe wetland (50 km northwest of Qinghai Lake) and 1 to Cuolongka Lake (220 km northwest of Qinghai Lake) during the nesting period. We identified nesting attempts of 7 of the marked geese at Qinghai Lake. Four completed successful nesting attempts according to our rules of judgment for the breeding status, and 2 geese lost broods soon after hatching (hereafter referred to as unsuccessful breeders). Of 18 geese present at Qinghai Lake during the nesting period, 9 (6 non-breeders, 2 successful breeders and 1 unsuccessful breeder) remained at Qinghai Lake during the moulting period; and 9 (5 non-breeders, 4 unsuccessful breeders) left Qinghai Lake for moulting. Kuhai Lake, Donggeicuona Lake, Alake Lake, Zhaling-Eling Lake area and Huangheyuan wetland area were used as moulting sites. Geese that moulted at Qinghai Lake, Cuolongka Lake, Kuhai Lake, Donggeicuona Lake and Alake Lake also moved to Zhaling-Eling Lake area or Huangheyuan wetland area and stayed there for several days prior to autumn migration. Mean home range and core area estimates did not differ significantly by sex, year and between breeders and non-breeders. ?? 2010 Dt. Ornithologen-Gesellschaft e.V.

Stellar mass distribution of S4G disk galaxies and signatures of bar-induced secular evolution

NASA Astrophysics Data System (ADS)

Díaz-García, S.; Salo, H.; Laurikainen, E.

2016-12-01

Context. Models of galaxy formation in a cosmological framework need to be tested against observational constraints, such as the average stellar density profiles (and their dispersion) as a function of fundamental galaxy properties (e.g. the total stellar mass). Simulation models predict that the torques produced by stellar bars efficiently redistribute the stellar and gaseous material inside the disk, pushing it outwards or inwards depending on whether it is beyond or inside the bar corotation resonance radius. Bars themselves are expected to evolve, getting longer and narrower as they trap particles from the disk and slow down their rotation speed. Aims: We use 3.6 μm photometry from the Spitzer Survey of Stellar Structure in Galaxies (S4G) to trace the stellar distribution in nearby disk galaxies (z ≈ 0) with total stellar masses 108.5 ≲ M∗/M⊙ ≲ 1011 and mid-IR Hubble types - 3 ≤ T ≤ 10. We characterize the stellar density profiles (Σ∗), the stellar contribution to the rotation curves (V3.6 μm), and the m = 2 Fourier amplitudes (A2) as a function of M∗ and T. We also describe the typical shapes and strengths of stellar bars in the S4G sample and link their properties to the total stellar mass and morphology of their host galaxy. Methods: For 1154 S4G galaxies with disk inclinations lower than 65°, we perform a Fourier decomposition and rescale their images to a common frame determined by the size in physical units, by their disk scalelength, and for 748 barred galaxies by both the length and orientation of their bars. We stack the resized density profiles and images to obtain statistically representative average stellar disks and bars in bins of M∗ and T. Based on the radial force profiles of individual galaxies we calculate the mean stellar contribution to the circular velocity. We also calculate average A2 profiles, where the radius is normalized to R25.5. Furthermore, we infer the gravitational potentials from the synthetic bars to obtain the tangential-to-radial force ratio (QT) and A2 profiles in the different bins. We also apply ellipse fitting to quantitatively characterize the shape of the bar stacks. Results: For M∗ ≥ 109M⊙, we find a significant difference in the stellar density profiles of barred and non-barred systems: (I) disks in barred galaxies show larger scalelengths (hR) and fainter extrapolated central surface brightnesses (Σ°); (II) the mean surface brightness profiles (Σ∗) of barred and non-barred galaxies intersect each other slightly beyond the mean bar length, most likely at the bar corotation; and (III) the central mass concentration of barred galaxies is higher (by almost a factor 2 when T ≤ 5) than in their non-barred counterparts. The averaged Σ∗ profiles follow an exponential slope down to at least 10 M⊙ pc-2, which is the typical depth beyond which the sample coverage in the radial direction starts to drop. Central mass concentrations in massive systems (≥1010M⊙) are substantially larger than in fainter galaxies, and their prominence scales with T. This segregation also manifests in the inner slope of the mean stellar component of the circular velocity: lenticular (S0) galaxies present the most sharply rising V3.6 μm. Based on the analysis of bar stacks, we show that early- and intermediate-type spirals (0 ≤ T< 5) have intrinsically narrower bars than later types and S0s, whose bars are oval-shaped. We show a clear agreement between galaxy family and quantitative estimates of bar strength. In early- and intermediate-type spirals, A2 is larger within and beyond the typical bar region among barred galaxies than in the non-barred subsample. Strongly barred systems also tend to have larger A2 amplitudes at all radii than their weakly barred counterparts. Conclusions: Using near-IR wavelengths (S4G 3.6 μm), we provide observational constraints that galaxy formation models can be checked against. In particular, we calculate the mean stellar density profiles, and the disk(+bulge) component of the rotation curve (and their dispersion) in bins of M∗ and T. We find evidence for bar-induced secular evolution of disk galaxies in terms of disk spreading and enhanced central mass concentration. We also obtain average bars (2D), and we show that bars hosted by early-type galaxies are more centrally concentrated and have larger density amplitudes than their late-type counterparts. The FITS files of the synthetic images and the tabulated radial profiles of the mean (and dispersion of) stellar mass density, 3.6 μm surface brightness, Fourier amplitudes, gravitational force, and the stellar contribution to the circular velocity are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/596/A84

A dynamical system perspective to understanding badminton singles game play.

PubMed

Chow, Jia Yi; Seifert, Ludovic; Hérault, Romain; Chia, Shannon Jing Yi; Lee, Miriam Chang Yi

2014-02-01

By altering the task constraints of cooperative and competitive game contexts in badminton, insights can be obtained from a dynamical systems perspective to investigate the underlying processes that results in either a gradual shift or transition of playing patterns. Positional data of three pairs of skilled female badminton players (average age 20.5±1.38years) were captured and analyzed. Local correlation coefficient, which provides information on the relationship of players' displacement data, between each pair of players was computed for angle and distance from base position. Speed scalar product was in turn established from speed vectors of the players. The results revealed two patterns of playing behaviors (i.e., in-phase and anti-phase patterns) for movement displacement. Anti-phase relation was the dominant coupling pattern for speed scalar relationships among the pairs of players. Speed scalar product, as a collective variable, was different between cooperative and competitive plays with a greater variability in amplitude seen in competitive plays leading to a winning point. The findings from this study provide evidence for increasing stroke variability to perturb existing stable patterns of play and highlights the potential for speed scalar product to be a collective variable to distinguish different patterns of play (e.g., cooperative and competitive). Copyright © 2013 Elsevier B.V. All rights reserved.

On wave dark matter in spiral and barred galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez-Medina, Luis A.; Matos, Tonatiuh; Bray, Hubert L., E-mail: lmedina@fis.cinvestav.mx, E-mail: bray@math.duke.edu, E-mail: tmatos@fis.cinvestav.mx

2015-12-01

We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark matter). Here we show how the interaction between a baryonic disk and its Dark Matter Halo triggers the formation of spiral structures when the halo is allowed to have a triaxial shape and angular momentum. This is a more realistic picture within the WDM model since a non-spherical rotating halo seems to be more natural. By performing hydrodynamic simulations, along with earlier test particlesmore » simulations, we demonstrate another important way in which wave dark matter is consistent with observations. The common existence of bars in these simulations is particularly noteworthy. This may have consequences when trying to obtain information about the dark matter distribution in a galaxy, the mere presence of spiral arms or a bar usually indicates that baryonic matter dominates the central region and therefore observations, like rotation curves, may not tell us what the DM distribution is at the halo center. But here we show that spiral arms and bars can develop in DM dominated galaxies with a central density core without supposing its origin on mechanisms intrinsic to the baryonic matter.« less

Inner shelf morphologic controls on the dynamics of the beach and bar system, Fire Island, New York

USGS Publications Warehouse

Hapke, Cheryl J.; Schwab, William C.; Gayes, Paul T.; McCoy, Clay; Viso, Richard; Lentz, Erika E.; Rosati, Julie D.; Wang, Ping; Roberts, Tiffany M.

2011-01-01

The mechanism of sediment exchange between offshore sand ridges and the beach at Fire Island, New York is largely unknown. However, recent evidence from repeat nearshore bathymetry surveys, coupled with the complex but consistent bar morphology and patterns of shoreline change demonstrate that there is a feedback occurring between the regional geologic framework and modern processes. Analysis of bathymetric survey data provides direct confirmation that the offshore ridges are connected to the shoreface and are spatially persistent. The fixed nature of the nearshore morphology is further supported by time series camera data that indicate persistent bars with breaks that re-form in the same locations. A long-term time series of shoreline change shows distinct zones of erosion and accretion that are pervasive over time scales greater than a half-century, and their length-scales are similar to the spacing of the offshore ridge-trough system. The first-order geologic framework is responsible for the existence and locations of the ridges and troughs, which then influence the morphodynamics of the beach and bar system.

The Influence of Shaping Air Pressure of Pneumatic Spray Gun

NASA Astrophysics Data System (ADS)

Chen, Wenzhuo; Chen, Yan; Pan, Haiwei; Zhang, Weiming; Li, Bo

2018-02-01

The shaping air pressure is a very important parameter in the application of pneumatic spray gun, and studying its influence on spray flow field and film thickness distribution has practical values. In this paper, Euler-Lagrangian method is adopted to describe the two-phase spray flow of pneumatic painting process, and the air flow fields, spray patterns and dynamic film thickness distributions were obtained with the help of the computational fluid dynamics code—ANSYS Fluent. Results show that with the increase of the shaping air pressure, the air phase flow field spreads in the plane perpendicular to the shaping air hole plane, the spray pattern becomes narrower and flatter, and the width of the dynamic film increases with the reduced maximum value of the film thickness. But the film thickness distribution seems to change little with the shaping air pressure decreasing from 0.6bar to 0.9bar.

Brain networks involved in tactile speed classification of moving dot patterns: the effects of speed and dot periodicity

PubMed Central

Yang, Jiajia; Kitada, Ryo; Kochiyama, Takanori; Yu, Yinghua; Makita, Kai; Araki, Yuta; Wu, Jinglong; Sadato, Norihiro

2017-01-01

Humans are able to judge the speed of an object’s motion by touch. Research has suggested that tactile judgment of speed is influenced by physical properties of the moving object, though the neural mechanisms underlying this process remain poorly understood. In the present study, functional magnetic resonance imaging was used to investigate brain networks that may be involved in tactile speed classification and how such networks may be affected by an object’s texture. Participants were asked to classify the speed of 2-D raised dot patterns passing under their right middle finger. Activity in the parietal operculum, insula, and inferior and superior frontal gyri was positively related to the motion speed of dot patterns. Activity in the postcentral gyrus and superior parietal lobule was sensitive to dot periodicity. Psycho-physiological interaction (PPI) analysis revealed that dot periodicity modulated functional connectivity between the parietal operculum (related to speed) and postcentral gyrus (related to dot periodicity). These results suggest that texture-sensitive activity in the primary somatosensory cortex and superior parietal lobule influences brain networks associated with tactually-extracted motion speed. Such effects may be related to the influence of surface texture on tactile speed judgment. PMID:28145505

Representation of tactile curvature in macaque somatosensory area 2

PubMed Central

Connor, Charles E.; Hsiao, Steven S.

2013-01-01

Tactile shape information is elaborated in a cortical hierarchy spanning primary (SI) and secondary somatosensory cortex (SII). Indeed, SI neurons in areas 3b and 1 encode simple contour features such as small oriented bars and edges, whereas higher order SII neurons represent large curved contour features such as angles and arcs. However, neural coding of these contour features has not been systematically characterized in area 2, the most caudal SI subdivision in the postcentral gyrus. In the present study, we analyzed area 2 neural responses to embossed oriented bars and curved contour fragments to establish whether curvature representations are generated in the postcentral gyrus. We found that many area 2 neurons (26 of 112) exhibit clear curvature tuning, preferring contours pointing in a particular direction. Fewer area 2 neurons (15 of 112) show preferences for oriented bars. Because area 2 response patterns closely resembled SII patterns, we also compared area 2 and SII response time courses to characterize the temporal dynamics of curvature synthesis in the somatosensory system. We found that curvature representations develop and peak concurrently in area 2 and SII. These results reveal that transitions from orientation tuning to curvature selectivity in the somatosensory cortical hierarchy occur within SI rather than between SI and SII. PMID:23536717

Microstructural Characterization of a Directionally-Solidified Ni-33 (at. %)Al-31Cr-3Mo Eutectic Alloy as a Function of Withdrawal Rate

NASA Technical Reports Server (NTRS)

Raj, S. V.; Locci, I. E.; Whittenberger, J. D.; Salem, J. A.

2000-01-01

The Ni-33 (at. %)Al-3lCr-3Mo eutectic alloy was directionally-solidified (DS) at different rates, V(sub I), varying between 2.5 to 508 mm/ h. Detailed qualitative and quantitative metallographic and chemical analyses were conducted on the directionally-solidified rods. The microstructures consisted of eutectic colonies with parallel lamellar NiAl/(Cr,Mo) plates for solidification rates at and below 12.7 mm/ h. Cellular eutectic microstructures were observed at higher solidification rates, where the plates exhibited a radial pattern. The microstructures were demonstrated to be fairly uniform throughout a 100 mm length of the DS zone by quantitative metallography. The average cell size, bar-d, decreased with increasing growth rate to a value of 125 microns at 508 mm/ h according to the relation bar-d (microns) approx. = 465 V(sup -0.22, sub I), where V(sub I) is in mm/ h. Both the average NiAl plate thickness, bar-Delta(sub NiAl), and the interlamellar spacing, bar-lambda, were observed to be constant for V(sub I) less than or = 50.8 mm/ h but decreased with increasing growth rate above this value as 0.93 bar-Delta(sub NiAl)(microns) = 61.2 V(sup -0.93, sub I) and bar-lambda (microns) = 47.7 V(sup -0.64, sub I), respectively. The present results are detailed on a microstructural map. Keywords Optical microscopy, microstructure, compounds intermetallic, directional solidification

Galactic rings revisited. II. Dark gaps and the locations of resonances in early-to-intermediate-type disc galaxies

NASA Astrophysics Data System (ADS)

Buta, Ronald J.

2017-10-01

Dark gaps are commonly seen in early-to-intermediate-type barred galaxies having inner and outer rings or related features. In this paper, the morphologies of 54 barred and oval ringed galaxies have been examined with the goal of determining what the dark gaps are telling us about the structure and evolution of barred galaxies. The analysis is based mainly on galaxies selected from the Galaxy Zoo 2 data base and the Catalogue of Southern Ringed Galaxies. The dark gaps between inner and outer rings are of interest because of their likely association with the L4 and L5 Lagrangian points that would be present in the gravitational potential of a bar or oval. Since the points are theoretically expected to lie very close to the corotation resonance (CR) of the bar pattern, the gaps provide the possibility of locating corotation in some galaxies simply by measuring the radius rgp of the gap region and setting rCR=rgp. With the additional assumption of generally flat rotation curves, the locations of other resonances can be predicted and compared with observed morphological features. It is shown that this `gap method' provides remarkably consistent interpretations of the morphology of early-to-intermediate-type barred galaxies. The paper also brings attention to cases where the dark gaps lie inside an inner ring, rather than between inner and outer rings. These may have a different origin compared to the inner/outer ring gaps.

Wind ripples in low density atmospheres

NASA Technical Reports Server (NTRS)

Miller, J. S.; Marshall, J. R.; Greeley, R.

1987-01-01

The effect of varying fluid density (rho) on particle transport was examined by conducting tests at atmospheric pressures between 1 and 0.004 bar in the Martian Surface Wind Tunnel (MARSWIT). This study specifically concerns the effect of varying rho on the character of wind ripples, and elicits information concerning generalized ripple models as well as specific geological circumstances for ripple formation such as those prevailing on Mars. Tests were conducted primarily with 95 micron quartz sand, and for each atmospheric pressure chosen, tests were conducted at two freestream wind speeds: 1.1 U*(t) and 1.5 U*(t), where U*(t) is saltation threshold. Preliminary analysis of the data suggests: (1) ballistic ripple wavelength is not at variance with model predictions; (2) an atmospheric pressure of approximately 0.2 bar could represent a discontinuity in ripple behavior; and (4) ripple formation on Mars may not be readily predicted by extrapolation of terrestrial observations.

[Modelling metallic bars in an orthopaedic laboratory: postural and biomechanical analysis].

PubMed

Draicchio, F; Miccio, A; Mari, S; Silvetti, A; Forzano, F; Ranavolo, A

2012-01-01

Aim of this work is to assess, with an objective technique (i.e. surface electromyography), the upper limb biomechanical load in workers specialized in manufacturing of orthopedic prostheses. We considered two different working configurations (workstation height at 105 and 110 cm) and three different materials to be modeled (aluminum, steel and titanium). Our results showed significant differences between aluminum/steel and titanium bars. As regards the working configurations, we found differences in the muscle activation patterns between the two heights, with an increased exertion of the shoulder muscles at 110 cm with respect to 105.

Evaluating the impact of a wide range of vegetation densities on river channel pattern

NASA Astrophysics Data System (ADS)

Pattison, Ian; Roucou, Ron

2016-04-01

Braided rivers are very dynamic systems which have complex controls over their planform and flow dynamics. Vegetation is one variable which influences channel geometry and pattern, through its effect on local flow hydraulics and the process continuum of sediment erosion-transport-deposition. Furthermore, where in the braided floodplain stable vegetation develops depends on the temporal sequencing of the river discharge i.e. floods. Understanding the effect of vegetation in these highly dynamic systems has multiple consequences for human activity and floodplain management. This paper focusses on the specific role of vegetation density in controlling braided river form and processes. Previous research in this field has been contradictory; with Gran and Paola (2001) finding that increasing vegetation density decreased the number of active channels. In contrast, Coulthard (2005] observed that as vegetation become denser there was an increase in the number of channels. This was hypothesized to be caused by flow separation around vegetation and the development of bars immediately downstream of the plant. This paper reports the results from a set of experiments in a 4m by 1m flume, where discharge, slope and sediment size were kept constant. Artificial grass was used to represent vegetation with a density ranging from 50 plants/m2 to 400 plants/m2. Digital photographs, using a GoPro camera with a fish eye lens, were taken from ~1m above the flume at an interval of 30 seconds during the 3 hour experiment. The experiments showed that as the vegetation density increased from 50 to 150 plants/m2, the number of channel bars developing doubled from 12 to 24. At vegetation densities greater than 150 plants/m2 there was a decline in the number of bars created to a minimum of 8 bars for a density of 400 plants/m2. We attribute these patterns to the effect that the vegetation has on flow hydraulics, sediment transport processes and the spatial patterns of erosion and deposition. We develop a simple conceptual model to explain the observations along the wide range of vegetation densities investigated. At low plant densities, each plant acted independently and caused flow separation and convergence around each plant, similar to in the Coulthard (2005] experiment. At medium densities, individual plants start to interact together with narrow channels developing longitudinally between vegetative bars. Finally at very high densities, there was both lateral and longitudinal interaction between plants meaning that flow was diverted around them forming wandering, meandering channels. In summary, the relationship between vegetation density and channel braiding is more complex than previous thought, taking a parabolic shape, with maximum braiding occurring at medium vegetation densities.

Wheeled and standard walkers in Parkinson's disease patients with gait freezing.

PubMed

Cubo, Esther; Moore, Charity G; Leurgans, Sue; Goetz, Christopher G

2003-10-01

Compare the efficacy of two walking assistance devices (wheeled walker and standard walker) to unassisted walking for patients with PD and gait freezing. Although numerous walking devices are used clinically, their relative effects on freezing and walking speed have never been systematically tested. Nineteen PD patients (14 non-demented) walked under three conditions in randomized order: unassisted walking, standard walker, and wheeled walker. Patients walked up to three times in each condition through a standard course that included rising from a chair, walking through a doorway, straightway walking, pivoting, and return. Total walking time, freezing time and number of freezes were compared for the three conditions using mixed models (walking time) and Friedman's test (freezing). The wheeled walker was further studied by comparing the effect of an attached laser that projected a bar of light on the floor as a visual walking cue. Use of either type of device significantly slowed walking compared to unassisted walking. Neither walker reduced any index of freezing, nor the laser attachment offered any advantage to the wheeled walker. The standard walker increased freezing, and the wheeled walker had no effect on freezing. Among the non-demented subjects (n=14), the same patterns occurred, although the walking speed was less impaired by the wheeled walker than the standard walker in this group. Though walkers may stabilize patients and increase confidence, PD patients walk more slowly when using them, without reducing freezing. Because the wheeled walker was intermediate for walking time and does not aggravate freezing, if walkers are used for these subjects, this type of walker should be favored.

Coevolution of bed surface patchiness and channel morphology: 1. Mechanisms of forced patch formation

USGS Publications Warehouse

Nelson, Peter A.; McDonald, Richard R.; Nelson, Jonathan M.; Dietrich, William E.

2015-01-01

Riverbeds frequently display a spatial structure where the sediment mixture composing the channel bed has been sorted into discrete patches of similar grain size. Even though patches are a fundamental feature in gravel bed rivers, we have little understanding of how patches form, evolve, and interact. Here we present a two-dimensional morphodynamic model that is used to examine in greater detail the mechanisms responsible for the development of forced bed surface patches and the coevolution of bed morphology and bed surface patchiness. The model computes the depth-averaged channel hydrodynamics, mixed-grain-size sediment transport, and bed evolution by coupling the river morphodynamic model Flow and Sediment Transport with Morphological Evolution of Channels (FaSTMECH) with a transport relation for gravel mixtures and the mixed-grain-size Exner equation using the active layer assumption. To test the model, we use it to simulate a flume experiment in which the bed developed a sequence of alternate bars and temporally and spatially persistent forced patches with a general pattern of coarse bar tops and fine pools. Cross-stream sediment flux causes sediment to be exported off of bars and imported into pools at a rate that balances downstream gradients in the streamwise sediment transport rate, allowing quasi-steady bar-pool topography to persist. The relative importance of lateral gravitational forces on the cross-stream component of sediment transport is a primary control on the amplitude of the bars. Because boundary shear stress declines as flow shoals over the bars, the lateral sediment transport is increasingly size selective and leads to the development of coarse bar tops and fine pools.

Mississippi River-Gulf Outlet, Louisiana, Field Data Report

DTIC Science & Technology

1990-08-01

Fisackerly, T. L. Fagerburg, H. A . Benson, and J. W. Parman, EPB. Data reduction was performed by Ms. C . J. Coleman, EPB, and Mr. Fagerburg. Laboratory...Measurements consisted of the following: a . Water levels recorded at six locations. b. Current speed and direction at three ranges. c . Suspended sediment...sampling tubing was attached to the solid suspension bar at the same elevation as the current meter and was pointed into the flow. A 12-v d- c pump was

On the Ignition and Combustion Variances of Jet Propellant-8 and Diesel Fuel in Military Diesel Engines

DTIC Science & Technology

2008-09-22

NA Displacement (cc) 1357 6468 Operating speeds (rpm) 800 – 3000 1500 – 3400 IMEP range (bar) 5 – 27 2 – 10 Boost system Shop air Turbocharger ...Council Diesel Fuel Workshop. Pickett, L.M. and Hoogterp, L., “ Fundamental Spray and Combustion Measurements of JP-8 at Diesel Conditions”, SAE...N., 1981, "Transient Performance Simulation and Analysis of Turbocharged Diesel Engines", SAE Paper 810338.

Surface fatigue life and failure characteristics of EX-53, CBS 1000M, and AISI 9310 gear materials

NASA Technical Reports Server (NTRS)

Townsend, D. P.

1985-01-01

Spur gear endurance tests and rolling-element surface fatigue tests are conducted to investigate EX-53 and CBS 1000M steels for use as advanced application gear materials, to determine their endurance characteristics, and to compare the results with the standard AISI 9310 gear material. The gear pitch diameter is 8.89 cm (3.50 in). Gear test conditions are an oil inlet temperature of 320 K (116 F), an oil outlet temperature of 350 K (170 F), a maximum Hertz stress of 1.71 GPa (248 ksi), and a speed of 10,000 rpm. Bench-type rolling-element fatigue tests are conducted at ambient temperature with a bar specimen speed of 12,500 rpm and a maximum Hertz stress of 4.83 GPa (700 ksi). The EX-53 test gears have a surface fatigue life of twice that of the AISI 9310 spur gears. The CBS 1000M test gears have a surface fatigue life of more than twice that of the AISI 9310 spur gears. However, the CBS 1000M gears experience a 30-percent tooth fracture failure which limits its use as a gear material. The rolling-contact fatigue lines of RC bar specimens of EX-53 and ASISI 9310 are approximately equal. However, the CBS 1000M RC specimens have a surface fatigue life of about 50 percent that of the AISI 9310.

Ultrafast high-repetition imaging of fuel sprays using picosecond fiber laser.

PubMed

Purwar, Harsh; Wang, Hongjie; Tang, Mincheng; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard; Godin, Thomas; Hideur, Ammar

2015-12-28

Modern diesel injectors operate at very high injection pressures of about 2000 bar resulting in injection velocities as high as 700 m/s near the nozzle outlet. In order to better predict the behavior of the atomization process at such high pressures, high-resolution spray images at high repetition rates must be recorded. However, due to extremely high velocity in the near-nozzle region, high-speed cameras fail to avoid blurring of the structures in the spray images due to their exposure time. Ultrafast imaging featuring ultra-short laser pulses to freeze the motion of the spray appears as an well suited solution to overcome this limitation. However, most commercial high-energy ultrafast sources are limited to a few kHz repetition rates. In the present work, we report the development of a custom-designed picosecond fiber laser generating ∼ 20 ps pulses with an average power of 2.5 W at a repetition rate of 8.2 MHz, suitable for high-speed imaging of high-pressure fuel jets. This fiber source has been proof tested by obtaining backlight images of diesel sprays issued from a single-orifice injector at an injection pressure of 300 bar. We observed a consequent improvement in terms of image resolution compared to standard white-light illumination. In addition, the compactness and stability against perturbations of our fiber laser system makes it particularly suitable for harsh experimental conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Baozhuo; Young, Marcus L.

Many technological applications of austenitic shape memory alloys (SMAs) involve cyclical mechanical loading and unloading in order to take advantage of pseudoelasticity. In this paper, we investigated the effect of mechanical bending of pseudoelastic NiTi SMA wires using high-energy synchrotron radiation X-ray diffraction (SR-XRD). Differential scanning calorimetry was performed to identify the phase transformation temperatures. Scanning electron microscopy images show that micro-cracks in compressive regions of the wire propagate with increasing bend angle, while tensile regions tend not to exhibit crack propagation. SR-XRD patterns were analyzed to study the phase transformation and investigate micromechanical properties. By observing the various diffraction peaks such as the austenite (200) and the martensite (more » $${\\bar 1}12$$), ($${\\bar 1}03$$), ($${\\bar 1}11$$), and (101) planes, intensities and residual strain values exhibit strong anisotropy, depending upon whether the sample is in compression or tension during bending.« less

Usability of Three-dimensional Augmented Visual Cues Delivered by Smart Glasses on (Freezing of) Gait in Parkinson’s Disease

PubMed Central

Janssen, Sabine; Bolte, Benjamin; Nonnekes, Jorik; Bittner, Marian; Bloem, Bastiaan R.; Heida, Tjitske; Zhao, Yan; van Wezel, Richard J. A.

2017-01-01

External cueing is a potentially effective strategy to reduce freezing of gait (FOG) in persons with Parkinson’s disease (PD). Case reports suggest that three-dimensional (3D) cues might be more effective in reducing FOG than two-dimensional cues. We investigate the usability of 3D augmented reality visual cues delivered by smart glasses in comparison to conventional 3D transverse bars on the floor and auditory cueing via a metronome in reducing FOG and improving gait parameters. In laboratory experiments, 25 persons with PD and FOG performed walking tasks while wearing custom-made smart glasses under five conditions, at the end-of-dose. For two conditions, augmented visual cues (bars/staircase) were displayed via the smart glasses. The control conditions involved conventional 3D transverse bars on the floor, auditory cueing via a metronome, and no cueing. The number of FOG episodes and percentage of time spent on FOG were rated from video recordings. The stride length and its variability, cycle time and its variability, cadence, and speed were calculated from motion data collected with a motion capture suit equipped with 17 inertial measurement units. A total of 300 FOG episodes occurred in 19 out of 25 participants. There were no statistically significant differences in number of FOG episodes and percentage of time spent on FOG across the five conditions. The conventional bars increased stride length, cycle time, and stride length variability, while decreasing cadence and speed. No effects for the other conditions were found. Participants preferred the metronome most, and the augmented staircase least. They suggested to improve the comfort, esthetics, usability, field of view, and stability of the smart glasses on the head and to reduce their weight and size. In their current form, augmented visual cues delivered by smart glasses are not beneficial for persons with PD and FOG. This could be attributable to distraction, blockage of visual feedback, insufficient familiarization with the smart glasses, or display of the visual cues in the central rather than peripheral visual field. Future smart glasses are required to be more lightweight, comfortable, and user friendly to avoid distraction and blockage of sensory feedback, thus increasing usability. PMID:28659862

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners.

PubMed

Kuhman, Daniel; Melcher, Daniel; Paquette, Max R

2016-01-01

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6 min mile(-1)) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.

Dynamic Dazzle Distorts Speed Perception.

PubMed

Hall, Joanna R; Cuthill, Innes C; Baddeley, Roland; Attwood, Angela S; Munafò, Marcus R; Scott-Samuel, Nicholas E

2016-01-01

Static high contrast ('dazzle') patterns, such as zigzags, have been shown to reduce the perceived speed of an object. It has not escaped our notice that this effect has possible military applications and here we report a series of experiments on humans, designed to establish whether dynamic dazzle patterns can cause distortions of perceived speed sufficient to provide effective defence in the field, and the extent to which these effects are robust to a battery of manipulations. Dynamic stripe patterns moving in the same direction as the target are found to increase the perceived speed of that target, whilst dynamic stripes moving in the opposite direction to the target reduce the perceived speed. We establish the optimum position for such dazzle patches; confirm that reduced contrast and the addition of colour do not affect the performance of the dynamic dazzle, and finally, using the CO2 challenge, show that the effect is robust to stressful conditions.

High-strain rate tensile characterization of graphite platelet reinforced vinyl ester based nanocomposites using split-Hopkinson pressure bar

NASA Astrophysics Data System (ADS)

Pramanik, Brahmananda

The dynamic response of exfoliated graphite nanoplatelet (xGnP) reinforced and carboxyl terminated butadiene nitrile (CTBN) toughened vinyl ester based nanocomposites are characterized under both dynamic tensile and compressive loading. Dynamic direct tensile tests are performed applying the reverse impact Split Hopkinson Pressure Bar (SHPB) technique. The specimen geometry for tensile test is parametrically optimized by Finite Element Analysis (FEA) using ANSYS Mechanical APDLRTM. Uniform stress distribution within the specimen gage length has been verified using high-speed digital photography. The on-specimen strain gage installation is substituted by a non-contact Laser Occlusion Expansion Gage (LOEG) technique for infinitesimal dynamic tensile strain measurements. Due to very low transmitted pulse signal, an alternative approach based on incident pulse is applied for obtaining the stress-time history. Indirect tensile tests are also performed combining the conventional SHPB technique with Brazilian disk test method for evaluating cylindrical disk specimens. The cylindrical disk specimen is held snugly in between two concave end fixtures attached to the incident and transmission bars. Indirect tensile stress is estimated from the SHPB pulses, and diametrical transverse tensile strain is measured using LOEG. Failure diagnosis using high-speed digital photography validates the viability of utilizing this indirect test method for characterizing the tensile properties of the candidate vinyl ester based nanocomposite system. Also, quasi-static indirect tensile response agrees with previous investigations conducted using the traditional dog-bone specimen in quasi-static direct tensile tests. Investigation of both quasi-static and dynamic indirect tensile test responses show the strain rate effect on the tensile strength and energy absorbing capacity of the candidate materials. Finally, the conventional compressive SHPB tests are performed. It is observed that both strength and energy absorbing capacity of these candidate material systems are distinctively less under dynamic tension than under compressive loading. Nano-reinforcement appears to marginally improve these properties for pure vinyl ester under dynamic tension, although it is found to be detrimental under dynamic compression.

A new high intensity and short-pulse molecular beam valve

NASA Astrophysics Data System (ADS)

Yan, B.; Claus, P. F. H.; van Oorschot, B. G. M.; Gerritsen, L.; Eppink, A. T. J. B.; van de Meerakker, S. Y. T.; Parker, D. H.

2013-02-01

In this paper, we report on the design and performance of a new home-built pulsed gas valve, which we refer to as the Nijmegen Pulsed Valve (NPV). The main output characteristics include a short pulse width (as short as 20 μs) combined with operating rates up to 30 Hz. The operation principle of the NPV is based on the Lorentz force created by a pulsed current passing through an aluminum strip located within a magnetic field, which opens the nozzle periodically. The amplitude of displacement of the opening mechanism is sufficient to allow the use of nozzles with up to 1.0 mm diameter. To investigate the performance of the valve, several characterizations were performed with different experimental methods. First, a fast ionization gauge was used to measure the beam intensity of the free jet emanating from the NPV. We compare free jets from the NPV with those from several other pulsed valves in current use in our laboratory. Results showed that a high intensity and short pulse-length beam could be generated by the new valve. Second, the NPV was tested in combination with a skimmer, where resonance enhanced multiphoton ionization combined with velocity map imaging was used to show that the NPV was able to produce a pulsed molecular beam with short pulse duration (˜20 μs using 0.1% NO/He at 6 bars) and low rotational temperature (˜1 K using 0.5% NO/Ar at 6 bars). Third, a novel two-point pump-probe method was employed which we label double delay scan. This method allows a full kinematic characterization of the molecular beam, including accurate speed ratios at different temporal positions. It was found that the speed ratio was maximum (S = 50 using 0.1% NO/He at 3 bars) at the peak position of the molecular beam and decreased when it was on the leading or falling edge.

High-speed data word monitor

NASA Technical Reports Server (NTRS)

Wirth, M. N.

1975-01-01

Small, portable, self-contained device provides high-speed display of bit pattern or any selected portion of transmission, can suppress filler patterns so that display is not updated, and can freeze display so that specific event may be observed in detail.

Modeling and measuring the relationships between sediment transport processes, alluvial bedforms and channel-scale morphodynamics in sandy braided rivers.

NASA Astrophysics Data System (ADS)

Nicholas, A. P.; Ashworth, P. J.; Best, J.; Lane, S. N.; Parsons, D. R.; Sambrook Smith, G.; Simpson, C.; Strick, R. J. P.; Unsworth, C. A.

2017-12-01

Recent years have seen significant advances in the development and application of morphodynamic models to simulate river evolution. Despite this progress, significant challenges remain to be overcome before such models can provide realistic simulations of river response to environmental change, or be used to determine the controls on alluvial channel patterns and deposits with confidence. This impasse reflects a wide range of factors, not least the fact that many of the processes that control river behaviour operate at spatial scales that cannot be resolved by such models. For example, sand-bed rivers are characterised by multiple scales of topography (e.g., dunes, bars, channels), the finest of which must often by parameterized, rather than represented explicitly in morphodynamic models. We examine these issues using a combination of numerical modeling and field observations. High-resolution aerial imagery and Digital Elevation Models obtained for the sandy braided South Saskatchewan River in Canada are used to quantify dune, bar and channel morphology and their response to changing flow discharge. Numerical simulations are carried out using an existing morphodynamic model based on the 2D shallow water equations, coupled with new parameterisations of the evolution and influence of alluvial bedforms. We quantify the spatial patterns of sediment flux using repeat images of dune migration and bar evolution. These data are used to evaluate model predictions of sediment transport and morphological change, and to assess the degree to which model performance is controlled by the parametrization of roughness and sediment transport phenomena linked to subgrid-scale bedforms (dunes). The capacity of such models to replicate the characteristic multi-scale morphology of bars in sand-bed rivers, and the contrasting morphodynamic signatures of braiding during low and high flow conditions, is also assessed.

Drinking Context and Drinking Problems Among Black, White, and Hispanic Men and Women in the 1984, 1995, and 2005 U.S. National Alcohol Surveys*

PubMed Central

Nyaronga, Dan; Greenfield, Thomas K.; McDaniel, Patricia A.

2009-01-01

Objective: The purpose of this study was to investigate the preferred drinking contexts of different gender and ethnic groups (white, black, and Hispanic men and women), by examining where these groups do most of their drinking and to what extent drinking contexts preferences are associated with certain drinking-related consequences. Method: The study used data from the 1984, 1995, and 2005 U.S. National Alcohol Surveys. Among current drinkers, cluster analyses of volume drunk in six contexts (restaurants, bars, others' parties, or when spending a quiet evening at home, having friends drop over at home, and hanging out in public places) were used to classify individuals by their drinking context preferences in each gender by ethnicity subgroup. Results: We identified three highly similar drinking context-preference clusters within each of the six subgroups: (1) bar-plus group (did most drinking in bars, plus much in other venues), (2) home group (did most drinking at home, and a fair amount elsewhere), and (3) light group (drank almost nothing quietly at home and also less in other settings than the other two clusters). For a number of ethnic-by-gender groups, context preference group assignment predicted drinking-related problems, over and above general drinking patterns. For example, for all groups, the bar-plus preference group relative to the light group showed higher risk of arguments, fighting, and drunk driving, after taking into account the volume consumed, frequency of heavy drinking, age, and year of survey. Conclusions: Examining individuals' preferred drinking contexts may provide important information to augment overall drinking patterns in risk and prevention studies. PMID:19118387

Effects of Exhaust Gas Recirculation on Performance and Emission Characteristic of SI Engine using Hydrogen and CNG Blends

NASA Astrophysics Data System (ADS)

Nitnaware, Pravin Tukaram; Suryawanshi, Jiwak G.

2018-01-01

This paper shows exhaust gas recirculation (EGR) effects on multi-cylinder bi-fuel SI engine using blends of 0, 5, 10 and 15% hydrogen by energy with CNG. All trials are performed at a speed of 3000, 3500 and 4000 rpm with EGR rate of 0, 5, 10 and 15%, with equal spark timing and injection pressure of 2.6 bar. At specific hydrogen percentage with increase in EGR rate NOx emission reduces drastically and increases with increase in hydrogen addition. Hydrocarbon (HC) and carbon monoxide (CO) emission decreases with increase in speed and hydrogen addition. There is considerable improvement in brake thermal efficiency (BTE) and brake specific energy consumption (BSEC) at 15% EGR rate. At 3000 rpm, 5% EGR rate with 5% hydrogen had shown maximum cylinder pressure. Brake specific fuel consumption (b.s.f.c) increased with increase in EGR rate and decreased with increase in hydrogen addition for all speeds.

Influence of Systematic Increases in Treadmill Walking Speed on Gait Kinematics After Stroke

PubMed Central

Tyrell, Christine M.; Roos, Margaret A.; Rudolph, Katherine S.

2011-01-01

Background Fast treadmill training improves walking speed to a greater extent than training at a self-selected speed after stroke. It is unclear whether fast treadmill walking facilitates a more normal gait pattern after stroke, as has been suggested for treadmill training at self-selected speeds. Given the massed stepping practice that occurs during treadmill training, it is important for therapists to understand how the treadmill speed selected influences the gait pattern that is practiced on the treadmill. Objective The purpose of this study was to characterize the effect of systematic increases in treadmill speed on common gait deviations observed after stroke. Design A repeated-measures design was used. Methods Twenty patients with stroke walked on a treadmill at their self-selected walking speed, their fastest speed, and 2 speeds in between. Using a motion capture system, spatiotemporal gait parameters and kinematic gait compensations were measured. Results Significant improvements in paretic- and nonparetic-limb step length and in single- and double-limb support were found. Asymmetry of these measures improved only for step length. Significant improvements in paretic hip extension, trailing limb position, and knee flexion during swing also were found as speed increased. No increases in circumduction or hip hiking were found with increasing speed. Limitations Caution should be used when generalizing these results to survivors of a stroke with a self-selected walking speed of less than 0.4 m/s. This study did not address changes with speed during overground walking. Conclusions Faster treadmill walking facilitates a more normal walking pattern after stroke, without concomitant increases in common gait compensations, such as circumduction. The improvements in gait deviations were observed with small increases in walking speed. PMID:21252308

Effect of loading on peak power of the bar, body, and system during power cleans, squats, and jump squats.

PubMed

McBride, Jeffrey M; Haines, Tracie L; Kirby, Tyler J

2011-08-01

Nine males (age 24.7 ± 2.1 years, height 175.3 ± 5.5 cm, body mass 80.8 ± 7.2 kg, power clean 1-RM 97.1 ± 6.36 kg, squat 1-RM = 138.3 ± 20.9 kg) participated in this study. On day 1, the participants performed a one-repetition maximum (1-RM) in the power clean and the squat. On days 2, 3, and 4, participants performed the power clean, squat or jump squat. Loading for the power clean ranged from 30% to 90% of the participant's power clean 1-RM and loading for the squat and jump squat ranged from 0% to 90% of the participant's squat 1-RM, all at 10% increments. Peak force, velocity, and power were calculated for the bar, body, and system (bar + body) for all power clean, squat, and jump squat trials. Results indicate that peak power for the bar, body, and system is differentially affected by load and movement pattern. When using the power clean, squat or jump squat for training, the optimal load in each exercise may vary. Throwing athletes or weightlifters may be most concerned with bar power, but jumpers or sprinters may be more concerned with body or system power. Thus, the exercise type and load vary according to the desired stimulus.

Characteristic study of flat spray nozzle by using particle image velocimetry (PIV) and ANSYS simulation method

NASA Astrophysics Data System (ADS)

Pairan, M. Rasidi; Asmuin, Norzelawati; Isa, Nurasikin Mat; Sies, Farid

2017-04-01

Water mist sprays are used in wide range of application. However it is depend to the spray characteristic to suit the particular application. This project studies the water droplet velocity and penetration angle generated by new development mist spray with a flat spray pattern. This research conducted into two part which are experimental and simulation section. The experimental was conducted by using particle image velocimetry (PIV) method, ANSYS software was used as tools for simulation section meanwhile image J software was used to measure the penetration angle. Three different of combination pressure of air and water were tested which are 1 bar (case A), 2 bar (case B) and 3 bar (case C). The flat spray generated by the new development nozzle was examined at 9cm vertical line from 8cm of the nozzle orifice. The result provided in the detailed analysis shows that the trend of graph velocity versus distance gives the good agreement within simulation and experiment for all the pressure combination. As the water and air pressure increased from 1 bar to 2 bar, the velocity and angle penetration also increased, however for case 3 which run under 3 bar condition, the water droplet velocity generated increased but the angle penetration is decreased. All the data then validated by calculate the error between experiment and simulation. By comparing the simulation data to the experiment data for all the cases, the standard deviation for this case A, case B and case C relatively small which are 5.444, 0.8242 and 6.4023.

Enhanced sediment loading facilitates point bar growth and accelerates bank erosion along a modelled meander bend on the Sacramento River, USA

NASA Astrophysics Data System (ADS)

Ahmed, J.; Constantine, J. A.; Hales, T. C.

2017-12-01

Meandering channels provide a conduit through which sediment and water is routed from the uplands to the sea. Alluvial material is periodically stored and transported through the channel network as permitted by the prevailing hydrologic conditions. The lowlands are typically characterised by accumulations of sediment attached to the inner banks of meander bends (point bars). These bedforms have been identified as important for facilitating a link between in-stream sediment supplies and channel dynamism. A 2D curvilinear hydrodynamic model (MIKE 21C) was used to perform a number of experiments in which the sediment load was adjusted to investigate how changes in alluvial material fluxes affect the development of point bars and the resultant patterns of bank erosion. A doubling of the sediment load caused a longitudinal increase in the bar in the upstream direction and caused a coeval doubling of the transverse channel slope at the meander apex. The upstream growth of the point bar was accompanied by an increase in length over which lateral migration took place at the outer bank. The magnitude of outer bank erosion was 9-times greater for the high-sediment simulation. These results suggest that enhanced sediment loads (potentially the result of changes in land use or climate) can trigger greater rates of bank erosion and channel change through the sequestration of alluvial material on point bars, which encourage high-velocity fluid deflection towards the outer bank of the meander. This controls riparian habitat development and exchanges of sediment and nutrients across the channel-floodplain interface.

Effect of Electrical Stimulation on Beta-Adrenergic Receptor Population and Coupling Efficiency in Chicken and Rat Skeleton Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Strietzel, Catherine J.

1999-01-01

Expression of the beta-adrenergic receptor (bAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the bAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for seven days in culture were subjected to electrical stimulation for an additional two days at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the bAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. Thus, in chicken muscle cells an enhanced level of contraction reduced the coupling efficiency of bAR for cyclic AMP production by approximately 55% compared to controls. In contrast, the bAR population in rat muscle cells was increased by approximately 25% by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was also increased by almost two-fold. Thus, in rat muscle cells an enhanced level of contraction increased the coupling efficiency of bAR for cyclic AMP production by approximately 50% compared to controls. The basal levels of intracellular cyclic AMP in both rat muscle cells and chicken muscle cells were not affected by electrical stimulation.

[Comparison of film-screen combinations in contrast-detail diagram and with interactive image analysis. 3: Trimodal histograms of gray scale distribution in bar groups of lead pattern images].

PubMed

Hagemann, G; Eichbaum, G; Stamm, G

1998-05-01

The following four screen film combinations were compared: a) a combination of anticrossover film and UV-light emitting screens, b) a combination of blue-light emitting screens and film and c) two conventional green fluorescing screen film combinations. Radiographs of a specially designed plexiglass phantom (0.2 x 0.2 x 0.12 m3) with bar patterns of lead and plaster and of air, respectively were obtained using the following parameters: 12 pulse generator, 0.6 mm focus size, 4.7 mm aluminum prefilter, a grid with 40 lines/cm (12:1) and a focus-detector distance of 1.15 m. Image analysis was performed using an Ibas system and a Zeiss Kontron computer. Display conditions were the following: display distance 0.12 m, a vario film objective 35/70 (Zeiss), a video camera tube with a PbO photocathode, 625 lines (Siemens Heimann), an Ibas image matrix of 512 x 512 pixels with a spatial resolution of ca. 7 cycles/mm, the projected matrix area was 5000 micron 2. Maxima in the histograms of a grouped bar pattern were estimated as mean values from the bar and gap regions ("mean value method"). They were used to calculate signal contrast, standard deviations of the means and scatter fraction. Comparing the histograms with respect to spatial resolution and kV setting a clear advantage of the UVR system becomes obvious. The quantitative analysis yielded a maximum spatial resolution of approx. 3 cycles/mm for the UVR system at 60 kV which decreased to half of this value at 117 kV caused by the increasing influence of scattered radiation. A ranking of screen-film systems with respect to image quality and dose requirement is presented. For its evaluation an interactive image analysis using the mean value method was found to be superior to signal/noise ratio measurements and visual analysis in respect to diagnostic relevance and saving of time.

Statistical pattern analysis of surficial karst in the Pleistocene Miami oolite of South Florida

NASA Astrophysics Data System (ADS)

Harris, Paul (Mitch); Purkis, Sam; Reyes, Bella

2018-05-01

A robust airborne light detection and ranging digital terrain model (LiDAR DTM) and select outcrops are used to examine the extent and characteristics of the surficial karst overprint of the late Pleistocene Miami oolite in South Florida. Subaerial exposure of the Miami oolite barrier bar and shoals to a meteoric diagenetic environment, lasting ca. 120 kyr from the end of the last interglacial highstand MIS 5e until today, has resulted in diagenetic alteration including surface and shallow subsurface dissolution producing extensive dolines and a few small stratiform caves. Analysis of the LiDAR DTM suggests that >50% of the dolines in the Miami oolite have been obscured/lost to urbanization, though a large number of depressions remain apparent and can be examined for trends and spatial patterns. The verified dolines are analyzed for their size and depth, their lateral distribution and relation to depositional topography, and the separation distance between them. Statistical pattern analysis shows that the average separation distance and average density of dolines on the strike-oriented barrier bar versus dip-oriented shoals is statistically inseparable. Doline distribution on the barrier bar is clustered because of the control exerted on dissolution by the depositional topography of the shoal system, whereas patterning of dolines in the more platform-ward lower-relief shoals is statistically indistinguishable from random. The areal extent and depth of dissolution of the dolines are well described by simple mathematical functions, and the depth of the dolines increases as a function of their size. The separation and density results from the Miami oolite are compared to results from other carbonate terrains. Near-surface, stratiform caves in the Miami oolite occur in sites where the largest and deepest dolines are present, and sit at, or near, the top of the present water table.

Progress on Development of the New FDIRC PID Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vavra, Jerry

2012-08-03

We present a progress status of a new concept of PID detector called FDIRC, intended to be used at the SuperB experiment, which requires {pi}/K separation up to a few GeV/c. The new photon camera is made of the solid fused-silica optics with a volume 25x smaller and speed increased by a factor of ten compared to the BaBar DIRC, and therefore will be much less sensitive to electromagnetic and neutron background

Research Requirements for Future Visual Guidance Systems

DTIC Science & Technology

1994-02-01

age in the 1960’s, and attendant higher speeds and aircraft sizes, improvements in signage became imperative. The John F. Kennedy ( JFK ) Airport in New...been carried out in the United States at JFK Airport in New York in the late 1980’s (reference 21). The costs of retrofitting the SEATAC airport with...Previous testing of abbreviated stop bars had been carried out in the United States at JFK Airport in New York in the late 1980’s. The costs of

Hypersonic Transition Experiments in 3D Cone Flow with New Measurement Techniques

DTIC Science & Technology

2012-08-01

flux. Computation by G. Candler (University of Minnesota). Flow conditions: p0 = 12bar, Re∞ = 9.5 × 10 6m-1 ...... 22 Figure 15: Power spectra of...Introduction One major uncertainty in the aerodynamic design of high-speed vehicles results from laminar- turbulent boundary layer (BL) transition...flush mounted to the surface. The diameter of the gauges is 3.18mm. The active area is of rectangular shape (0.762×0.762mm²). Power was supplied by two

Experimental rotordynamic coefficient results for honeycomb seals

NASA Technical Reports Server (NTRS)

Elrod, David A.; Childs, Dara W.

1988-01-01

Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

Evaluation of the performance of orthodontic devices using FBG sensors

NASA Astrophysics Data System (ADS)

Carvalho, L.; Roriz, P.; Frazão, O.; Marques, M. B.

2015-04-01

Cross-bite, as a malocclusion effect, is defined as a transversal changing of the upper dental arch, in relation to the lower arch, and may be classified as skeletal, dental or functional. As a consequence, the expansion of maxilla is an effective clinical treatment used to correct transversal maxillary discrepancy. The maxillary expansion is an ancient method used in orthodontics, for the correction of the maxillary athresia with posterior crossbite, through the opening of the midpalatal suture (disjunction), using orthodontic- orthopaedic devices. Same controversial discussion arises among the clinicians, about the effects of each orthodontic devices as also about the technique to be employed. The objective of this study was to compare the strain field induced by two different orthodontic devices, named disjunctor with and without a connecting bar, in an acrylic model jaw, using fiber Bragg grating sensors to measure the strain patterns. The orthodontic device disjunctor with the bar, in general, transmits higher forces and strain to teeth and maxillae, than with the disjunctor without bar. It was verified that the strain patterns were not symmetric between the left and the right sides as also between the posterior and anterior regions of the maxillae. For the two devices is also found that in addition a displacement in the horizontal plane, particularly in posterior teeth, also occurs a rotation corresponding to a vestibularization of the posterior teeth and their alveolar processes.

Shoulder muscles recruitment during a power backward giant swing on high bar: a wavelet-EMG-analysis.

PubMed

Frère, Julien; Göpfert, Beat; Slawinski, Jean; Tourny-Chollet, Claire

2012-04-01

This study aimed at determining the upper limb muscles coordination during a power backward giant swing (PBGS) and the recruitment pattern of motor units (MU) of co-activated muscles. The wavelet transformation (WT) was applied to the surface electromyographic (EMG) signal of eight shoulder muscles. Total gymnast's body energy and wavelet synergies extracted from the WT-EMG by using a non-negative matrix factorization were analyzed as a function of the body position angle of the gymnast. A cross-correlation analysis of the EMG patterns allowed determining two main groups of co-activated muscles. Two wavelet synergies representing the main spectral features (82% of the variance accounted for) discriminated the recruitment of MU. Although no task-group of MU was found among the muscles, it appeared that a higher proportion of fast MU was recruited within the muscles of the first group during the upper part of the PBGS. The last increase of total body energy before bar release was induced by the recruitment of the muscles of the second group but did not necessitate the recruitment of a higher proportion of fast MU. Such muscle coordination agreed with previous simulations of elements on high bar as well as the findings related to the recruitment of MU. Copyright © 2012 Elsevier B.V. All rights reserved.

[Comparison of film-screen combination in a contrast detail diagram and with interactive image analysis. 1: Contrast detail diagram].

PubMed

Hagemann, G; Eichbaum, G

1997-07-01

The following three film-screen combinations were compared: a) a combination of anticrossover film and UV-light emitting screens, b) a combination of blue-light emitting screens and film, and c) a conventional green fluorescing screen film combination. Radiographs of a specially designed plexiglass phantom (0.2 x 0.2 x 0.12 m3) were obtained that contained bar patterns of lead and plaster (calcium sulfate) to test high and intermediate contrast resolution and bar patterns of air to test low contrast resolution, respectively. An aluminum step wedge was integrated to evaluate dose-density curves of the radiographs. The dose values for the various step thicknesses were measured as percentage of the dose value in air for 60, 81, and 117 kV. Exposure conditions were the following: 12 pulse generator, 0.6 mm focus size, 4.7 mm aluminum prefilter, a grid with 40 lines/cm (12:1), and a focus-detector distance of 1.15 m. The thresholds of visible bars of the various pattern materials were assessed by seven radiologists, one technician, and the authors. The resulting contrast detail diagram could not prove any significant differences between the three tested screen film combinations. The pairwise comparison, however, found 8 of the 18 paired differences to be statistically significant between the conventional and the two new screen-film combinations. The authors concluded that subjective visual assessment of the threshold in a contrast detail study alone is of only limited value to grade image quality if no well-defined criteria are used (BIR report 20 [1989] 137-139). The statistical approach of paired differences of the estimated means appeared to be more appropriate.

Document Image Parsing and Understanding using Neuromorphic Architecture

DTIC Science & Technology

2015-03-01

processing speed at different layers. In the pattern matching layer, the computing power of multicore processors is explored to reduce the processing...developed to reduce the processing speed at different layers. In the pattern matching layer, the computing power of multicore processors is explored... cortex where the complex data is reduced to abstract representations. The abstract representation is compared to stored patterns in massively parallel

Fast Fourier single-pixel imaging via binary illumination.

PubMed

Zhang, Zibang; Wang, Xueying; Zheng, Guoan; Zhong, Jingang

2017-09-20

Fourier single-pixel imaging (FSI) employs Fourier basis patterns for encoding spatial information and is capable of reconstructing high-quality two-dimensional and three-dimensional images. Fourier-domain sparsity in natural scenes allows FSI to recover sharp images from undersampled data. The original FSI demonstration, however, requires grayscale Fourier basis patterns for illumination. This requirement imposes a limitation on the imaging speed as digital micro-mirror devices (DMDs) generate grayscale patterns at a low refreshing rate. In this paper, we report a new strategy to increase the speed of FSI by two orders of magnitude. In this strategy, we binarize the Fourier basis patterns based on upsampling and error diffusion dithering. We demonstrate a 20,000 Hz projection rate using a DMD and capture 256-by-256-pixel dynamic scenes at a speed of 10 frames per second. The reported technique substantially accelerates image acquisition speed of FSI. It may find broad imaging applications at wavebands that are not accessible using conventional two-dimensional image sensors.

Effect of high-pressure homogenization preparation on mean globule size and large-diameter tail of oil-in-water injectable emulsions.

PubMed

Peng, Jie; Dong, Wu-Jun; Li, Ling; Xu, Jia-Ming; Jin, Du-Jia; Xia, Xue-Jun; Liu, Yu-Ling

2015-12-01

The effect of different high pressure homogenization energy input parameters on mean diameter droplet size (MDS) and droplets with > 5 μm of lipid injectable emulsions were evaluated. All emulsions were prepared at different water bath temperatures or at different rotation speeds and rotor-stator system times, and using different homogenization pressures and numbers of high-pressure system recirculations. The MDS and polydispersity index (PI) value of the emulsions were determined using the dynamic light scattering (DLS) method, and large-diameter tail assessments were performed using the light-obscuration/single particle optical sensing (LO/SPOS) method. Using 1000 bar homogenization pressure and seven recirculations, the energy input parameters related to the rotor-stator system will not have an effect on the final particle size results. When rotor-stator system energy input parameters are fixed, homogenization pressure and recirculation will affect mean particle size and large diameter droplet. Particle size will decrease with increasing homogenization pressure from 400 bar to 1300 bar when homogenization recirculation is fixed; when the homogenization pressure is fixed at 1000 bar, the particle size of both MDS and percent of fat droplets exceeding 5 μm (PFAT 5 ) will decrease with increasing homogenization recirculations, MDS dropped to 173 nm after five cycles and maintained this level, volume-weighted PFAT 5 will drop to 0.038% after three cycles, so the "plateau" of MDS will come up later than that of PFAT 5 , and the optimal particle size is produced when both of them remained at plateau. Excess homogenization recirculation such as nine times under the 1000 bar may lead to PFAT 5 increase to 0.060% rather than a decrease; therefore, the high-pressure homogenization procedure is the key factor affecting the particle size distribution of emulsions. Varying storage conditions (4-25°C) also influenced particle size, especially the PFAT 5 . Copyright © 2015. Published by Elsevier B.V.

FLUVIAL DISTURBANCE AND WETLAND VEGETATION DEVELOPMENT, UPPER MAIN STEM, WILLAMETTE RIVER, OREGON, USA

EPA Science Inventory

Hydrogeomorphic processes drive vegetation establishment, and promote development of diverse wetland and riparian types associated with lotic ecosystems. The main objective of this study was to estimate the rate and pattern of vegetation development on bars tracked since 1936, a...

Color and luminance in the perception of 1- and 2-dimensional motion.

PubMed

Farell, B

1999-08-01

An isoluminant color grating usually appears to move more slowly than a luminance grating that has the same physical speed. Yet a grating defined by both color and luminance is seen as perceptually unified and moving at a single intermediate speed. In experiments measuring perceived speed and direction, it was found that color- and luminance-based motion signals are combined differently in the perception of 1-D motion than they are in the perception of 2-D motion. Adding color to a moving 1-D luminance pattern, a grating, slows its perceived speed. Adding color to a moving 2-D luminance pattern, a plaid made of orthogonal gratings, leaves its perceived speed unchanged. Analogous results occur for the perception of the direction of 2-D motion. The visual system appears to discount color when analyzing the motion of luminance-bearing 2-D patterns. This strategy has adaptive advantages, making the sensing of object motion more veridical without sacrificing the ability to see motion at isoluminance.

The effects of bending speed on the lumbo-pelvic kinematics and movement pattern during forward bending in people with and without low back pain.

PubMed

Tsang, Sharon M H; Szeto, Grace P Y; Li, Linda M K; Wong, Dim C M; Yip, Millie M P; Lee, Raymond Y W

2017-04-17

Impaired lumbo-pelvic movement in people with low back pain during bending task has been reported previously. However, the regional mobility and the pattern of the lumbo-pelvic movement were found to vary across studies. The inconsistency of the findings may partly be related to variations in the speed at which the task was executed. This study examined the effects of bending speeds on the kinematics and the coordination lumbo-pelvic movement during forward bending, and to compare the performance of individuals with and without low back pain. The angular displacement, velocity and acceleration of the lumbo-pelvic movement during the repeated forward bending executed at five selected speeds were acquired using the three dimensional motion tracking system in seventeen males with low back pain and eighteen males who were asymptomatic. The regional kinematics and the degree of coordination of the lumbo-pelvic movement during bending was compared and analysed between two groups. Significantly compromised performance in velocity and acceleration of the lumbar spine and hip joint during bending task at various speed levels was shown in back pain group (p < 0.01). Both groups displayed a high degree of coordination of the lumbo-pelvic displacement during forward bending executed across the five levels of speed examined. Significant between-group difference was revealed in the coordination of the lumbo-pelvic velocity and acceleration (p < 0.01). Asymptomatic group moved with a progressively higher degree of lumbo-pelvic coordination for velocity and acceleration while the back pain group adopted a uniform lumbo-pelvic pattern across all the speed levels examined. The present findings show that bending speed imposes different levels of demand on the kinematics and pattern of the lumbo-pelvic movement. The ability to regulate the lumbo-pelvic movement pattern during the bending task that executed at various speed levels was shown only in pain-free individuals but not in those with low back pain. Individuals with low back pain moved with a stereotyped strategy at their lumbar spine and hip joints. This specific aberrant lumbo-pelvic movement pattern may have a crucial role in the maintenance of the chronicity in back pain.

Imaging Electron Motion in a Few Layer MoS2 Device

NASA Astrophysics Data System (ADS)

Bhandari, S.; Wang, K.; Watanabe, K.; Taniguchi, T.; Kim, P.; Westervelt, R. M.

2017-06-01

Ultrathin sheets of MoS2 are a newly discovered 2D semiconductor that holds great promise for nanoelectronics. Understanding the pattern of current flow will be crucial for developing devices. In this talk, we present images of current flow in MoS2 obtained with a Scanned Probe Microscope (SPM) cooled to 4 K. We previously used this technique to image electron trajectories in GaAs/AlGaAs heterostructures and graphene. The charged SPM tip is held just above the sample surface, creating an image charge inside the device that scatters electrons. By measuring the change in resistance ΔR while the tip is raster scanned above the sample, an image of electron flow is obtained. We present images of electron flow in an MoS2 device patterned into a hall bar geometry. A three-layer MoS2 sheet is encased by two hBN layers, top and bottom, and patterned into a hall-bar with multilayer graphene contacts. An SPM image shows the current flow pattern from the wide contact at the end of the device for a Hall density n = 1.3×1012 cm-2. The SPM tip tends to block flow, increasing the resistance R. The pattern of flow was also imaged for a narrow side contact on the sample. At density n = 5.4×1011 cm-2; the pattern seen in the SPM image is similar to the wide contact. The ability to image electron flow promises to be very useful for the development of ultrathin devices from new 2D materials.

Plantar loading and foot-strike pattern changes with speed during barefoot running in those with a natural rearfoot strike pattern while shod.

PubMed

Cooper, Danielle M; Leissring, Sarah K; Kernozek, Thomas W

2015-06-01

Claims of injury reduction related to barefoot running has resulted in interest from the running public; however, its risks are not well understood for those who typically wear cushioned footwear. Examine how plantar loading changes during barefoot running in a group of runners that ordinarily wear cushioned footwear and demonstrate a rearfoot strike pattern (RFSP) without cueing or feedback alter their foot strike pattern and plantar loading when asked to run barefoot at different speeds down a runway. Forty-one subjects ran barefoot at three different speeds across a pedography platform which collected plantar loading variables for 10 regions of the foot; data were analyzed using two-way mixed multivariate analysis of variance (MANOVA). A significant foot strike position (FSP)×speed interaction in each of the foot regions indicated that plantar loading differed based on FSP across the different speeds. The RFSP provided the highest total forces across the foot while the pressures displayed in subjects with a non-rearfoot strike pattern (NRFSP) was more similar between each of the metatarsals. The majority of subjects ran barefoot with a NRFSP and demonstrated lower total forces and more uniform force distribution across the metatarsal regions. This may have an influence in injuries sustained in barefoot running. Copyright © 2015 Elsevier Ltd. All rights reserved.

EFFECTS OF NON-CIRCULAR MOTIONS ON AZIMUTHAL COLOR GRADIENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez-Garcia, Eric E.; Gonzalez-Lopezlira, Rosa A.; Gomez, Gilberto C., E-mail: emartinez@cida.v, E-mail: r.gonzalez@crya.unam.m, E-mail: g.gomez@crya.unam.m

2009-12-20

Assuming that density waves trigger star formation, and that young stars preserve the velocity components of the molecular gas where they are born, we analyze the effects that non-circular gas orbits have on color gradients across spiral arms. We try two approaches, one involving semianalytical solutions for spiral shocks, and another with magnetohydrodynamic (MHD) numerical simulation data. We find that, if non-circular motions are ignored, the comparison between observed color gradients and stellar population synthesis models would in principle yield pattern speed values that are systematically too high for regions inside corotation, with the difference between the real and themore » measured pattern speeds increasing with decreasing radius. On the other hand, image processing and pixel averaging result in systematically lower measured spiral pattern speed values, regardless of the kinematics of stellar orbits. The net effect is that roughly the correct pattern speeds are recovered, although the trend of higher measured OMEGA{sub p} at lower radii (as expected when non-circular motions exist but are neglected) should still be observed. We examine the MartInez-GarcIa et al. photometric data and confirm that this is indeed the case. The comparison of the size of the systematic pattern speed offset in the data with the predictions of the semianalytical and MHD models corroborates that spirals are more likely to end at outer Lindblad resonance, as these authors had already found.« less

Wind speed statistics for Goldstone, California, anemometer sites

NASA Technical Reports Server (NTRS)

Berg, M.; Levy, R.; Mcginness, H.; Strain, D.

1981-01-01

An exploratory wind survey at an antenna complex was summarized statistically for application to future windmill designs. Data were collected at six locations from a total of 10 anemometers. Statistics include means, standard deviations, cubes, pattern factors, correlation coefficients, and exponents for power law profile of wind speed. Curves presented include: mean monthly wind speeds, moving averages, and diurnal variation patterns. It is concluded that three of the locations have sufficiently strong winds to justify consideration for windmill sites.

Measurement of dynamic patterns of an elastic membrane at bi-modal vibration using high speed electronic speckle pattern interferometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preciado, Jorge Sanchez; Lopez, Carlos Perez; Santoyo, Fernando Mendoza

2014-05-27

Implementing a hybrid arrangement of Laser Doppler Vibrometry (LDV) and high speed Electronic Speckle Pattern Interferometry (ESPI) we were able to measure the dynamic patterns of a flat rectangular elastic membrane clamped at its edges stimulated with the sum of two resonance frequencies. ESPI is a versatile technique to analyze in real-time the deformation of a membrane since its low computational cost and easy implementation of the optical setup. Elastic membranes present nonlinear behaviors when stimulated with low amplitude signals. The elastic membrane under test, with several non rational related vibrating modals below the 200 Hz, was stimulated with twomore » consecutives resonant frequencies. The ESPI patterns, acquired at high speed rates, shown a similar behavior for the dual frequency stimulation as in the case of patterns formed with the entrainment frequency. We think this may be related to the effects observed in the application of dual frequency stimulation in ultrasound.« less

Tool for Forecasting Cool-Season Peak Winds Across Kennedy Space Center and Cape Canaveral Air Force Station

NASA Technical Reports Server (NTRS)

Barrett, Joe H., III; Roeder, William P.

2010-01-01

The expected peak wind speed for the day is an important element in the daily morning forecast for ground and space launch operations at Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS). The 45th Weather Squadron (45 WS) must issue forecast advisories for KSC/CCAFS when they expect peak gusts for >= 25, >= 35, and >= 50 kt thresholds at any level from the surface to 300 ft. In Phase I of this task, the 45 WS tasked the Applied Meteorology Unit (AMU) to develop a cool-season (October - April) tool to help forecast the non-convective peak wind from the surface to 300 ft at KSC/CCAFS. During the warm season, these wind speeds are rarely exceeded except during convective winds or under the influence of tropical cyclones, for which other techniques are already in use. The tool used single and multiple linear regression equations to predict the peak wind from the morning sounding. The forecaster manually entered several observed sounding parameters into a Microsoft Excel graphical user interface (GUI), and then the tool displayed the forecast peak wind speed, average wind speed at the time of the peak wind, the timing of the peak wind and the probability the peak wind will meet or exceed 35, 50 and 60 kt. The 45 WS customers later dropped the requirement for >= 60 kt wind warnings. During Phase II of this task, the AMU expanded the period of record (POR) by six years to increase the number of observations used to create the forecast equations. A large number of possible predictors were evaluated from archived soundings, including inversion depth and strength, low-level wind shear, mixing height, temperature lapse rate and winds from the surface to 3000 ft. Each day in the POR was stratified in a number of ways, such as by low-level wind direction, synoptic weather pattern, precipitation and Bulk Richardson number. The most accurate Phase II equations were then selected for an independent verification. The Phase I and II forecast methods were compared using an independent verification data set. The two methods were compared to climatology, wind warnings and advisories issued by the 45 WS, and North American Mesoscale (NAM) model (MesoNAM) forecast winds. The performance of the Phase I and II methods were similar with respect to mean absolute error. Since the Phase I data were not stratified by precipitation, this method's peak wind forecasts had a large negative bias on days with precipitation and a small positive bias on days with no precipitation. Overall, the climatology methods performed the worst while the MesoNAM performed the best. Since the MesoNAM winds were the most accurate in the comparison, the final version of the tool was based on the MesoNAM winds. The probability the peak wind will meet or exceed the warning thresholds were based on the one standard deviation error bars from the linear regression. For example, the linear regression might forecast the most likely peak speed to be 35 kt and the error bars used to calculate that the probability of >= 25 kt = 76%, the probability of >= 35 kt = 50%, and the probability of >= 50 kt = 19%. The authors have not seen this application of linear regression error bars in any other meteorological applications. Although probability forecast tools should usually be developed with logistic regression, this technique could be easily generalized to any linear regression forecast tool to estimate the probability of exceeding any desired threshold . This could be useful for previously developed linear regression forecast tools or new forecast applications where statistical analysis software to perform logistic regression is not available. The tool was delivered in two formats - a Microsoft Excel GUI and a Tool Command Language/Tool Kit (Tcl/Tk) GUI in the Meteorological Interactive Data Display System (MIDDS). The Microsoft Excel GUI reads a MesoNAM text file containing hourly forecasts from 0 to 84 hours, from one model run (00 or 12 UTC). The GUI then displays e peak wind speed, average wind speed, and the probability the peak wind will meet or exceed the 25-, 35- and 50-kt thresholds. The user can display the Day-1 through Day-3 peak wind forecasts, and separate forecasts are made for precipitation and non-precipitation days. The MIDDS GUI uses data from the NAM and Global Forecast System (GFS), instead of the MesoNAM. It can display Day-1 and Day-2 forecasts using NAM data, and Day-1 through Day-5 forecasts using GFS data. The timing of the peak wind is not displayed, since the independent verification showed that none of the forecast methods performed significantly better than climatology. The forecaster should use the climatological timing of the peak wind (2248 UTC) as a first guess and then adjust it based on the movement of weather features.

Assessing patterns of bed-material storage and flux on a mixed bedrock-alluvium river: Umpqua River Oregon, USA

NASA Astrophysics Data System (ADS)

Wallick, R.; Anderson, S.; Keith, M.; Cannon, C.; O'Connor, J. E.

2010-12-01

Gravel bed rivers in the Pacific Northwest and elsewhere provide an important source of commercial aggregate. Mining in-stream gravel, however, can alter channel and bar morphology, resulting in habitat degradation for aquatic species. In order to sustainably manage rivers subject to in-stream gravel extraction, regulatory agencies in Oregon have requested that the USGS complete a series of comprehensive geomorphic and sediment transport studies to provide context for regulatory-agency management of in-stream gravel extraction in Oregon streams. The Umpqua River in western Oregon poses special challenges to this type of assessment. Whereas most rivers subject to gravel extraction are relatively rich in bed-material sediment, the Umpqua River is a mixed bedrock-alluvium system draining a large (1,804 km2) basin; hence typical bed-material transport analyses and ecologic and geomorphic lessons of in-stream gravel extraction on more gravel-rich rivers have limited applicability. Consequently, we have relied upon multiple analyses, including comprehensive historical mapping, bedload transport modeling, and a GIS-based sediment yield analysis to assess patterns of bed-material transport and annual rates of bed-material flux. These analyses, combined with numerous historical accounts, indicate that since at least the 1840’s, the Umpqua River planform has been stable, as bar geometry is largely fixed by valley physiography and the channel itself is underlain mainly by bedrock. Preliminary estimates of annual bedload transport rates calculated for the period 1951-2008 from bed-material transport capacity relations at 42 bars along the South Umpqua and mainstem Umpqua Rivers vary from 0 to 600,000 metric tons per year, with this large spread reflecting variability in bar geometry and grainsize. Large stable bars are activated only during exceptionally large floods and have negligible transport during most years whereas smaller, low elevation bars serve as transient storage for gravel transported during typical flood events. A more plausible range of average annual transport rates, based on bedload transport capacity estimates for bars with reasonable values for reference shear stress, is 500-50,000 metric tons/year. Our sediment yield and mapping analyses support these more conservative estimates, providing annual transport rates of 13,000-50,000 metric tons per year for the South Umpqua River and mainstem Umpqua River through the Coast Range. Downstream, predicted flux rates decrease as attrition exceeds input of bed material, gradually diminishing to 30,000-40,000 metric tons at the head of tide. Because bed-material transport along the supply-limited Umpqua River is highly variable in time and space, the range of predicted flux values is thought to characterize the upper bounds of annual gravel transport.

Bar dynamics and channel junctions in scale-experiments of estuaries

NASA Astrophysics Data System (ADS)

Leuven, J.; Braat, L.; van Dijk, W. M.; Haas, T. D.; Kleinhans, M. G.

2017-12-01

The evolution of channels and bars in estuaries has high socio-economic relevance, with strong implications for navigation, dredging and ecology. However, the spatial and temporal evolution of channels and bars in estuaries is poorly understood. Here, we study feedbacks of bar morphodynamics on widening and narrowing of estuaries. Therefore, we conducted an experiment in a 20 m long and 3 m wide tilting flume (the 'Metronome'), in which we monitored the evolution of a self-formed estuary that developed from an intial straight channel into an irregular planform with multiple channels, braided bars and a meandering ebb channel. At locations where the estuary width is confined, major channel junctions occur, while the zones between the junctions are characterised by high braiding indices, periodically migrating channels and a relatively large estuary width. The junction locations were forced by the in- and outflow locations on the sides of the ebb-tidal delta and at the location where the channel pattern transitions from multiple channels into a single channel. In the middle of the estuary, self-confinement occurred by sedimentation on the sides of the estuary, which caused another major junction. The channel orientation at the junctions steers the morphodynamics of channels and bars immediately landward and seaward, because the orientation of inflow from the ebb-tidal delta and landward river perpetually varies. In natural systems major junction locations are mostly forced by inherited geology or human engineering. However, this study concludes that even without external forcing, the estuary planform will not converge to an ideal shape but will self-confine at major junctions and widens in the adjacent zones, resulting in an irregular planform shape.

Turbulent dispersion of the icing cloud from spray nozzles used in icing tunnels

NASA Technical Reports Server (NTRS)

Marek, C. J.; Olsen, W. A., Jr.

1986-01-01

To correctly simulate flight in natural icing conditions, the turbulence in an icing simulator must be as low as possible. But some turbulence is required to mix the droplets from the spray nozzles and achieve an icing cloud of uniform liquid water content. The goal for any spray system is to obtain the widest possible spray cloud with the lowest possible turbulence in the test section of a icing tunnel. This investigation reports the measurement of turbulence and the three-dimensional spread of the cloud from a single spray nozzle. The task was to determine how the air turbulence and cloud width are affected by spray bars of quite different drag coefficients, by changes in the turbulence upstream of the spray, the droplet size, and the atomizing air. An ice accretion grid, located 6.3 m downstream of the single spray nozzle, was used to measure cloud spread. Both the spray bar and the grid were located in the constant velocity test section. Three spray bar shapes were tested: the short blunt spray bar used in the NASA Lewis Icing Research Tunnel, a thin 14.6 cm chord airfoil, and a 53 cm chord NACA 0012 airfoil. At the low airspeed (56 km/hr) the ice accretion pattern was axisymmetric and was not affected by the shape of the spray bar. At the high airspeed (169 km/hr) the spread was 30 percent smaller than at the low airspeed. For the widest cloud the spray bars should be located as far upstream in the low velocity plenum of the icing tunnel. Good comparison is obtained between the cloud spread data and predicitons from a two-dimensional cloud mixing computer code using the two equation turbulence (k epsilon g) model.

Computational Study of Near-limit Propagation of Detonation in Hydrogen-air Mixtures

NASA Technical Reports Server (NTRS)

Yungster, S.; Radhakrishnan, K.

2002-01-01

A computational investigation of the near-limit propagation of detonation in lean and rich hydrogen-air mixtures is presented. The calculations were carried out over an equivalence ratio range of 0.4 to 5.0, pressures ranging from 0.2 bar to 1.0 bar and ambient initial temperature. The computations involved solution of the one-dimensional Euler equations with detailed finite-rate chemistry. The numerical method is based on a second-order spatially accurate total-variation-diminishing (TVD) scheme, and a point implicit, first-order-accurate, time marching algorithm. The hydrogen-air combustion was modeled with a 9-species, 19-step reaction mechanism. A multi-level, dynamically adaptive grid was utilized in order to resolve the structure of the detonation. The results of the computations indicate that when hydrogen concentrations are reduced below certain levels, the detonation wave switches from a high-frequency, low amplitude oscillation mode to a low frequency mode exhibiting large fluctuations in the detonation wave speed; that is, a 'galloping' propagation mode is established.

Real-time Mesoscale Visualization of Dynamic Damage and Reaction in Energetic Materials under Impact

NASA Astrophysics Data System (ADS)

Chen, Wayne; Harr, Michael; Kerschen, Nicholas; Maris, Jesus; Guo, Zherui; Parab, Niranjan; Sun, Tao; Fezzaa, Kamel; Son, Steven

Energetic materials may be subjected to impact and vibration loading. Under these dynamic loadings, local stress or strain concentrations may lead to the formation of hot spots and unintended reaction. To visualize the dynamic damage and reaction processes in polymer bonded energetic crystals under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar and a light gas gun. Controlled compressive loading was applied on PBX specimens with a single or multiple energetic crystal particles and impact-induced damage and reaction processes were captured using the high speed X-ray imaging setup. Impact velocities were systematically varied to explore the critical conditions for reaction. At lower loading rates, ultrasonic exercitations were also applied to progressively damage the crystals, eventually leading to reaction. AFOSR, ONR.

Non-volatile memory based on the ferroelectric photovoltaic effect

PubMed Central

Guo, Rui; You, Lu; Zhou, Yang; Shiuh Lim, Zhi; Zou, Xi; Chen, Lang; Ramesh, R.; Wang, Junling

2013-01-01

The quest for a solid state universal memory with high-storage density, high read/write speed, random access and non-volatility has triggered intense research into new materials and novel device architectures. Though the non-volatile memory market is dominated by flash memory now, it has very low operation speed with ~10 μs programming and ~10 ms erasing time. Furthermore, it can only withstand ~105 rewriting cycles, which prevents it from becoming the universal memory. Here we demonstrate that the significant photovoltaic effect of a ferroelectric material, such as BiFeO3 with a band gap in the visible range, can be used to sense the polarization direction non-destructively in a ferroelectric memory. A prototype 16-cell memory based on the cross-bar architecture has been prepared and tested, demonstrating the feasibility of this technique. PMID:23756366

Characterization of galactic bars from 3.6 μm S4G imaging

NASA Astrophysics Data System (ADS)

Díaz-García, S.; Salo, H.; Laurikainen, E.; Herrera-Endoqui, M.

2016-03-01

Context. Stellar bars play an essential role in the secular evolution of disk galaxies because they are responsible for the redistribution of matter and angular momentum. Dynamical models predict that bars become stronger and longer in time, while their rotation speed slows down. Aims: We use the Spitzer Survey of Stellar Structure in Galaxies (S4G) 3.6 μm imaging to study the properties (length and strength) and fraction of bars at z = 0 over a wide range of galaxy masses (M∗ ≈ 108-1011 M⊙) and Hubble types (-3 ≤ T ≤ 10). Methods: We calculated gravitational forces from the 3.6 μm images for galaxies with a disk inclination lower than 65°. We used the maximum of the tangential-to-radial force ratio in the bar region (Qb) as a measure of the bar-induced perturbation strength for a sample of ~600 barred galaxies. We also used the maximum of the normalized m = 2 Fourier density amplitude (A2max) to characterize the bar. Bar sizes were estimated I) visually; II) from ellipse fitting; III) from the radii of the strongest torque; and iv) from the radii of the largest m = 2 Fourier amplitude in the bar region. By combining our force calculations with the H I kinematics from the literature, we estimated the ratio of the halo-to-stellar mass (Mh/M∗) within the optical disk and by further using the universal rotation curve models, we obtained a first-order model of the rotation curve decomposition of 1128 disk galaxies. Results: We probe possible sources of uncertainty in our Qb measurements: the assumed scale height and its radial variation, the influence of the spiral arms torques, the effect of non-stellar emission in the bar region, and the dilution of the bar forces by the dark matter halo (our models imply that only ~10% of the disks in our sample are maximal). We find that for early- and intermediate-type disks (-3 ≤ T< 5), the relatively modest influence of the dark matter halo leads to a systematic reduction of the mean Qb by about 10-15%, which is of the same order as the uncertainty associated with estimating the vertical scale height. The halo correction on Qb becomes important for later types, implying a reduction of ~20-25% for T = 7-10. Whether the halo correction is included or not, the mean Qb shows an increasing trend with T. However, the mean A2max decreases for lower mass late-type systems. These opposing trends are most likely related to the reduced force dilution by bulges when moving towards later type galaxies. Nevertheless, when treated separately, both the early- and late-type disk galaxies show a strong positive correlation between Qb and A2max. For spirals the mean ɛ ≈ 0.5 is nearly independent of T, but it drops among S0s (≈0.2). The Qb and ɛ show a relatively tight dependence, with only a slight difference between early and late disks. For spirals, all our bar strength indicators correlate with the bar length (scaled to isophotal size). Late-type bars are longer than previously found in the literature. The bar fraction shows a double-humped distribution in the Hubble sequence (~75% for Sab galaxies), with a local minimum at T = 4 (~40%), and it drops for M∗ ≲ 109.5-10 M⊙. If we use bar identification methods based on Fourier decomposition or ellipse fitting instead of the morphological classification, the bar fraction decreases by ~30-50% for late-type systems with T ≥ 5 and correlates with Mh/M∗. Our Mh/M∗ ratios agree well with studies based on weak lensing analysis, abundance matching, and halo occupation distribution methods, under the assumption that the halo inside the optical disk contributes roughly a constant fraction of the total halo mass (~4%). Conclusions: We find possible evidence for the growth of bars within a Hubble time; as (1) bars in early-type galaxies show larger density amplitudes and disk-relative sizes than their intermediate-type counterparts; and (2) long bars are typically strong. We also observe two clearly distinct types of bars, between early- and intermediate-type galaxies (T< 5) on one side, and the late-type systems on the other, based on the differences in the bar properties. Most likely this distinction is connected to the higher halo-to-stellar ratio that we observe in later types, which affects the disk stability properties. Full Tables A.1-A.3, the tabulated radial force profiles, and the rotation curve decomposition model of each individual galaxy are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A160

Strain measurement in a concrete beam by use of the Brillouin-scattering-based distributed fiber sensor with single-mode fibers embedded in glass fiber reinforced polymer rods and bonded to steel reinforcing bars.

PubMed

Zeng, Xiaodong; Bao, Xiaoyi; Chhoa, Chia Yee; Bremner, Theodore W; Brown, Anthony W; DeMerchant, Michael D; Ferrier, Graham; Kalamkarov, Alexander L; Georgiades, Anastasis V

2002-08-20

The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is +/-15 microepsilon (microm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and +/-5 microepsilon with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are +/-7 and +/-15 microepsilon for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is +/-20 microepsilon for the two-point loading case.

HIV type 1 subtypes among bar and hotel workers in Moshi, Tanzania.

PubMed

Kiwelu, Ireen E; Renjifo, Boris; Chaplin, Beth; Sam, Noel; Nkya, Watoky M M M; Shao, John; Kapiga, Saidi; Essex, Max

2003-01-01

The HIV-1 prevalence among bar and hotel workers in Tanzania suggests they are a high-risk group for HIV-1 infection. We determined the HIV-1 subtype of 3'-p24/5'-p7 gag and C2-C5 env sequences from 40 individuals representing this population in Moshi. Genetic patterns composed of A(gag)-A(env), C(gag)-C(env), and D(gag)-D(env) were found in 19 (48.0%), 8 (20.0%), and 3 (8.0%) samples, respectively. The remaining 10 samples (25%) had different subtypes in gag and env, indicative of intersubtype recombinants. Among these recombinants, two contained sequences from HIV-1 subsubtype A2, a new genetic variant in Tanzania. Five bar and hotel workers may have been infected with viruses from a common source, based on phylogenetic analysis. The information obtained by surveillance of HIV-1 subtypes in a high-risk population should be useful in the design and evaluation of behavioral, therapeutic, and vaccine trial interventions aimed at reducing HIV-1 transmission.

Application of Gurson–Tvergaard–Needleman Constitutive Model to the Tensile Behavior of Reinforcing Bars with Corrosion Pits

PubMed Central

Xu, Yidong; Qian, Chunxiang

2013-01-01

Based on meso-damage mechanics and finite element analysis, the aim of this paper is to describe the feasibility of the Gurson–Tvergaard–Needleman (GTN) constitutive model in describing the tensile behavior of corroded reinforcing bars. The orthogonal test results showed that different fracture pattern and the related damage evolution process can be simulated by choosing different material parameters of GTN constitutive model. Compared with failure parameters, the two constitutive parameters are significant factors affecting the tensile strength. Both the nominal yield and ultimate tensile strength decrease markedly with the increase of constitutive parameters. Combining with the latest data and trial-and-error method, the suitable material parameters of GTN constitutive model were adopted to simulate the tensile behavior of corroded reinforcing bars in concrete under carbonation environment attack. The numerical predictions can not only agree very well with experimental measurements, but also simplify the finite element modeling process. PMID:23342140

Erosion by catastrophic floods on Mars and Earth

USGS Publications Warehouse

Baker, V.R.; Milton, D.J.

1974-01-01

The large Martian channels, especially Kasei, Ares, Tiu, Simud, and Mangala Valles, show morphologic features strikingly similar to those of the Channeled Scabland of eastern Washington, produced by the catastrophic breakout floods of Pleistocene Lake Missoula. Features in the overall pattern include the great size, regional anastomosis, and low sinuosity of the channels. Erosional features are streamlined hills, longitudinal grooves, inner channel cataracts, scour upstream of flow obstacles, and perhaps marginal cataracts and butte and basin topography. Depositional features are bar complexes in expanding reaches and perhaps pendant bars and alcove bars. Scabland erosion takes place in exceedingly deep, swift floodwater acting on closely jointed bedrock as a hydrodynamic consequence of secondary flow phenomena, including various forms of macroturbulent votices and flow separations. If the analogy to the Channeled Scabland is correct, floods involving water discharges of millions of cubic meters per second and peak flow velocities of tens of meters per second, but perhaps lasting no more than a few days, have occurred on Mars. ?? 1974.

Anatomy of a lower Mississippian oil reservoir, West Virginia, United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patchen, D.; Hohn, M.E.; McDowell, R.

1993-09-01

Several lines of evidence indicate that the oil reservoir in Granny Creek field is compartmentalized due to internal heterogeneities: an analysis of initial open flows vs. year completed and well location; mapping of initial open flows and cumulative production; and the nonuniform behavior of injection pressures and rates in waterflood patterns. The Big Injun sandstones includes an upper, coarse-grained, fluvial channel facies, and a lower, fine-grained, distributary mouthbar facies. The bar facies is the main reservoir, and can be subdivided into crest, distal, and proximal subfacies. Low original porosity and permeability in the poorly sorted channel facies was reduced furthermore » by quartz cementation. In contrast, chlorite coatings restricted quartz cementation and preserved porosity and permeability in the proximal bar subfacies. Small, low-amplitude folds plunge northeastward on the flank of the main syncline in which the fields is located. These minor structural highs seem to match areas of high initial open flows and cumulative production. High production also occurs where the distal and marine-influenced, proximal mouth-bar subfacies pinch out against at least a few feet of the relatively impremeable channel facies. Lower production is associated with (1) thin areas of proximal mouth-bar subfacies; (2) a change from marine to fluvial dominance of the bar facies, which is accompanied by a reduction in porosity and permeability; and (3) loss of the less permeable channel facies above the porous reservoir sandstone, due to downcutting by regional erosion that produced a post-Big Injun unconformity.« less

Two-dimensional shear wave speed and crawling wave speed recoveries from in vitro prostate data

PubMed Central

Lin, Kui; McLaughlin, Joyce R.; Thomas, Ashley; Parker, Kevin; Castaneda, Benjamin; Rubens, Deborah J.

2011-01-01

The crawling wave experiment was developed to capture a shear wave induced moving interference pattern that is created by two harmonic vibration sources oscillating at different but almost the same frequencies. Using the vibration sonoelastography technique, the spectral variance image reveals a moving interference pattern. It has been shown that the speed of the moving interference pattern, i.e., the crawling wave speed, is proportional to the shear wave speed with a nonlinear factor. This factor can generate high-speed artifacts in the crawling wave speed images that do not actually correspond to increased stiffness. In this paper, an inverse algorithm is developed to reconstruct both the crawling wave speed and the shear wave speed using the phases of the crawling wave and the shear wave. The feature for the data is the application to in vitro prostate data, while the features for the algorithm include the following: (1) A directional filter is implemented to obtain a wave moving in only one direction; and (2) an L1 minimization technique with physics inspired constraints is employed to calculate the phase of the crawling wave and to eliminate jump discontinuities from the phase of the shear wave. The algorithm is tested on in vitro prostate data measured at the Rochester Center for Biomedical Ultrasound and University of Rochester. Each aspect of the algorithm is shown to yield image improvement. The results demonstrate that the shear wave speed images can have less artifacts than the crawling wave images. Examples are presented where the shear wave speed recoveries have excellent agreement with histology results on the size, shape, and location of cancerous tissues in the glands. PMID:21786924

Young adults: vulnerable new targets of tobacco marketing.

PubMed

Biener, Lois; Albers, Alison B

2004-02-01

We examined young adult smoking patterns and receptivity to cigarette advertising to assess vulnerability to tobacco marketing strategies. We obtained data from a telephone survey of 12,072 Massachusetts adults. Smokers aged 18 to 30 years were more likely than older adults to smoke only occasionally and to consume fewer than 10 cigarettes per day. They also were more receptive to cigarette marketing and were more likely to be frequent patrons of bars and clubs. Many young adult smokers are in the initiation phase of smoking and are likely to undergo a transition to either nonsmoking or heavier smoking. If unimpeded by regulation, tobacco promotion in bars and clubs is likely to lead to increased adult smoking prevalence.

Characterization of new types of stationary phases for fast liquid chromatographic applications.

PubMed

Fekete, Szabolcs; Fekete, Jeno; Ganzler, Katalin

2009-12-05

The performance of a narrow bore silica based monolith column (5 cm x 2 mm) was compared to 5 cm long narrow bore (internal diameter < or = 2.1 mm) columns, packed with shell particles (2.7 microm) and totally porous sub-2 microm particles (1.5 microm, 1.7 microm and 1.9 microm) in gradient and isocratic elution separations of steroids. The highest peak capacity could be achieved with the column packed with 1.5 microm totally porous particles. The columns packed with porous 1.7 microm and shell 2.7 microm particles showed very similar capacity. The monolith column provided the lowest capacity during gradient elution. The plate height (HETP) of the 2.7 microm Ascentis Express column was very similar to the HETP obtained with 1.5 microm and 1.7 microm totally porous particles. The Chromolith monolithic column displayed an efficiency that is comparable to that of columns packed with spherical particles having their diameter between 3 microm and 4 microm. A kinetic plot analysis is presented to compare the theoretical analysis speed of different separation media. At 200 bar, the monolith column provided the highest performance when the required plate number was higher than 5000 (N>5000), however the efficiency drifted off faster in the range of N<5000 than in the case of packed columns. If the possibility of maximum performance was utilized (1000 bar for sub-2 microm particles, 600 bar for shell particles and 200 bar for monolith column) the monolith column would provide the poorest efficiency, while the column, packed with 1.5 microm particles offered the shortest impedance time.

Modeling internal ballistics of gas combustion guns.

PubMed

Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

2016-05-01

Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur.

[Reinforcement for overdentures on abutment teeth].

PubMed

Osada, Tomoko

2006-04-01

This study investigated the effect of the position of reinforcement wires, differences in artificial teeth, and framework designs on the breaking strength of overdentures. The basal surfaces of composite resin teeth and acrylic resin teeth were removed using a carbide bur. A reinforcement wire or a wrought palatal bar was embedded near the occlusal surface or basal surface. Four types of framework structures were designed : conventional skeleton (skeleton), housing with skeleton (housing), housing plus short metal backing (metal backing), and housing plus long metal backing (double structure). After the wires, bars, and frameworks were sand-blasted with 50 microm Al(2)O(3) powder, they were primed with a metal primer and embedded in a heat-polymerized denture base resin. The breaking strengths (N) and maximum stiffness (N/mm) of two-week aged (37 degrees C) specimens were measured using a bending test (n=8). All data obtained at a crosshead speed of 2.0 mm/min were analyzed by ANOVA/Tukey's test (alpha=0.01). There were no statistical differences between the two kinds of artificial teeth (p>0.01). The wrought palatal bar had significantly higher strength than the reinforcement wire (p<0.01). Greater strengths were found for specimens with frameworks than those without frameworks (p<0.01). The breaking strength of the wrought palatal bar embedded near the occlusal surface was higher than that on the basal surface (p>0.01). The breaking strength and maximum stiffness of the double structure framework were significantly greater (p<0.01) than those of the conventional frameworks. The breaking strengths of overdentures were influenced by the size and position of the reinforcement wires. Double structure frameworks are recommended for overdentures to promote a long-term prognosis without denture breakage.

The Tremaine-Weinberg Method for Pattern Speeds Using Hα Emission from Ionized Gas

NASA Astrophysics Data System (ADS)

Beckman, J. E.; Fathi, K.; Piñol, N.; Toonen, S.; Hernandez, O.; Carignan, C.

2008-10-01

The Fabry-Perot interferometer FaNTOmM was used at the 3.6-m CFHT and the 1.6-m Mont Mégantic Telescope to obtain data cubes in Hα of 9 nearby spiral galaxies from which maps in integrated intensity, velocity, and velocity dispersion were derived. We then applied the Tremaine-Weinberg method, in which the pattern speed can be deduced from its velocity field, by finding the integrated value of the mean velocity along a slit parallel to the major axis weighted by the intensity and divided by the weighted mean distance of the velocity points from the tangent point measured along the slit. The measured variables can be used either to make separate calculations of the pattern speed and derive a mean, or in a plot of one against the other for all the points on all slits, from which a best fit value can be derived. Linear fits were found for all the galaxies in the sample. For two galaxies a clearly separate inner pattern speed with a higher value, was also identified and measured.

Impact of the winter 2013-2014 series of severe Western Europe storms on a double-barred sandy coast: Beach and dune erosion and megacusp embayments

NASA Astrophysics Data System (ADS)

Castelle, Bruno; Marieu, Vincent; Bujan, Stéphane; Splinter, Kristen D.; Robinet, Arhur; Sénéchal, Nadia; Ferreira, Sophie

2015-06-01

The winter of 2013/2014 was characterized by a striking pattern of temporal and spatial extreme storm wave clustering in Western Europe. The 110-km long Gironde coast, SW France, was exposed to the most energetic wave conditions over the last 18 years. The period was outstanding in terms of the available energy to move sediment and cause large-scale erosion with the 2-month average significant wave height (Hs) exceeding 3.6 m, just below the 0.95 quantile, and 4 distinct 10-year return period storms with Hs > 9 m. These storm waves caused unprecedented beach and dune erosion along the Gironde coast, including severely damaged sea defences at the coastal towns. At the end of the winter, dune erosion scarp height was highly variable alongshore and often exceeded 10 m. Megacusp embayments were observed along the Gironde coast with an average alongshore spacing of 1000 m in the south progressively decreasing to 500 m in the north, with an average cross-shore amplitude of 20 m. While beach megacusps were previously observed to systematically couple to the inner bar along the Gironde coast during low- to moderate-energy wave conditions, severe storm-driven megacusp embayments cutting the dune were found to be enforced and coupled to the outer crescentic bar. A detailed inspection of the 1500 m-long bimonthly topographic surveys of Truc Vert beach shows that in early January 2014 the outstanding shore-normal incident storm swell 'Hercules', with Hs and peak wave period Tp peaking at 9.6 m and 22 s, respectively, triggered the formation of a localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m. The subsequent storms progressively smoothed the megacusp by the end of the winter, mostly through severe erosion of the megacusp horns. Because of the very long period (16 s < Tp < 23 s) storm waves with persistent shore-normal incidence, the well-developed outer crescentic bar observed prior to the winter did not straighten. Instead, the outer-bar three-dimensionality developed further, particularly during 'Hercules'. Our observations indicate that both the antecedent outer sandbar morphology and storm wave characteristics, including period and angle of incidence, govern patterns of beach and dune erosion along open multiple-barred sandy coasts during severe storms.

Tsunami Speed Variations in Density-stratified Compressible Global Oceans

NASA Astrophysics Data System (ADS)

Watada, S.

2013-12-01

Recent tsunami observations in the deep ocean have accumulated unequivocal evidence that tsunami traveltime delays compared with the linear long-wave tsunami simulations occur during tsunami propagation in the deep ocean. The delay is up to 2% of the tsunami traveltime. Watada et al. [2013] investigated the cause of the delay using the normal mode theory of tsunamis and attributed the delay to the compressibility of seawater, the elasticity of the solid earth, and the gravitational potential change associated with mass motion during the passage of tsunamis. Tsunami speed variations in the deep ocean caused by seawater density stratification is investigated using a newly developed propagator matrix method that is applicable to seawater with depth-variable sound speeds and density gradients. For a 4-km deep ocean, the total tsunami speed reduction is 0.45% compared with incompressible homogeneous seawater; two thirds of the reduction is due to elastic energy stored in the water and one third is due to water density stratification mainly by hydrostatic compression. Tsunami speeds are computed for global ocean density and sound speed profiles and characteristic structures are discussed. Tsunami speed reductions are proportional to ocean depth with small variations, except for in warm Mediterranean seas. The impacts of seawater compressibility and the elasticity effect of the solid earth on tsunami traveltime should be included for precise modeling of trans-oceanic tsunamis. Data locations where a vertical ocean profile deeper than 2500 m is available in World Ocean Atlas 2009. The dark gray area indicates the Pacific Ocean defined in WOA09. a) Tsunami speed variations. Red, gray and black bars represent global, Pacific, and Mediterranean Sea, respectively. b) Regression lines of the tsunami velocity reduction for all oceans. c)Vertical ocean profiles at grid points indicated by the stars in Figure 1.

Linking human impacts within an estuary to ebb-tidal delta evolution

USGS Publications Warehouse

Dallas, Kate L.; Barnard, Patrick L.

2009-01-01

San Francisco Bay, California, USA is among the most anthropogenically altered estuaries in the entire United States, but the impact on sediment transport to the coastal ocean has not been quantified. Analysis of four historic bathymetric surveys has revealed large changes to the morphology of the San Francisco Bar, an ebb-tidal delta at the mouth of the San Francisco Bay. From 1873 to 2005 the bar eroded an average of 80 cm, which equates to a total volume loss of 100 + 65 x 106 m3 of sediment. Comparison of the surveys indicates the entire ebb delta has contracted radially while its crest has moved landward an average of 1 km. Compilation of historic records reveals that 130 x 106 m3 of sediment has been permanently removed from the San Francisco Bay and adjacent coastal ocean. Constriction of the bar is hypothesized to be from a decrease in sediment supply from San Francisco Bay, a reduction in the tidal prism of the estuary, and/or a reduction in the input of hydraulic mining debris. Changes to the morphology of the San Francisco Bar have likely altered wave refraction and focusing patterns on adjacent beaches and may be a factor in persistent beach erosion occurring in the area.

Experimental and artificial neural network based prediction of performance and emission characteristics of DI diesel engine using Calophyllum inophyllum methyl ester at different nozzle opening pressure

NASA Astrophysics Data System (ADS)

Vairamuthu, G.; Thangagiri, B.; Sundarapandian, S.

2018-01-01

The present work investigates the effect of varying Nozzle Opening Pressures (NOP) from 220 bar to 250 bar on performance, emissions and combustion characteristics of Calophyllum inophyllum Methyl Ester (CIME) in a constant speed, Direct Injection (DI) diesel engine using Artificial Neural Network (ANN) approach. An ANN model has been developed to predict a correlation between specific fuel consumption (SFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), Unburnt hydrocarbon (UBHC), CO, CO2, NOx and smoke density using load, blend (B0 and B100) and NOP as input data. A standard Back-Propagation Algorithm (BPA) for the engine is used in this model. A Multi Layer Perceptron network (MLP) is used for nonlinear mapping between the input and the output parameters. An ANN model can predict the performance of diesel engine and the exhaust emissions with correlation coefficient (R2) in the range of 0.98-1. Mean Relative Errors (MRE) values are in the range of 0.46-5.8%, while the Mean Square Errors (MSE) are found to be very low. It is evident that the ANN models are reliable tools for the prediction of DI diesel engine performance and emissions. The test results show that the optimum NOP is 250 bar with B100.

Evaluation of Stress Distribution on Implant-Retained Auricular Prostheses: The Finite Element Method.

PubMed

Abbas, Ahmed A; Santiwong, Peerapong; Wonglamsam, Amornrat; Srithavaj, Theerathavaj; Chanthasopeephan, Teeranoot

The purpose of this study was to evaluate stress distribution around two craniofacial implants in an auricular prosthesis according to the removal forces. Three attachment combinations were used to evaluate the stress distribution under removal forces of 45 and 90 degrees. Three attachment designs were examined: (1) a Hader bar with three clips; (2) a Hader bar with one clip and two extracoronal resilient attachments (ERAs); and (3) a Hader bar with one clip and two Locators. The removal force was determined by means of an Instron universal testing machine with a crosshead speed of 10 mm/minute. All three designs were created in three dimensions using SolidWorks. The applied removal force and the models were then introduced to finite element software to analyze the stress distribution. The angle of removal force greatly affected the magnitude and direction of stress distribution on the implants. The magnitude of stress under the 45-degree removal force was higher than the stress at 90 degrees. The combination of the 1,000-g retention clip and 2,268-g retention Locator exhibited the highest stress on the implant flange when the removal force was applied at 45 degrees. The removal angle greatly influences the amount of force and stress on the implants. Prosthodontists are encouraged to inform patients to remove the prosthesis at 90 degrees and, if possible, use a low-retentive attachment to reduce stress.

Physically Modeling Stream Channel Adjustment to Woody Riparian Vegetation

NASA Astrophysics Data System (ADS)

Bennett, S. J.; Alonso, C. V.

2003-12-01

Stream restoration designs often use vegetation to promote bank and channel stability, to facilitate point-bar development, and to encourage natural colonization of riparian species. Here we examine the adjustment of an alluvial channel to in-stream and riparian vegetation using a distorted Froude-scale flume model with a movable boundary. A decimeter-scale trapezoidal channel comprised of 0.8-mm diameter sand was systematically vegetated with emergent, rigid dowels (3-mm in diameter) in rectangular and hemispherical patterns with varying vegetation densities while conserving the shape of the zone and the geometry of the vegetal patterns. Alternate sides of the channel were vegetated at the prescribed spacing of equilibrium alternate bars, ca. 5 to 7 times the channel width. Using flow conditions just below the threshold of sediment motion, flow obstruction, deflection, and acceleration caused bed erosion, bank failure, and morphologic channel adjustments that were wholly attributable to the managed plantings. As vegetation density increased, the magnitude and rate of scaled channel adjustment increased, which included increased channel widths, bankline steepening and meandering, and thalweg meandering. As the modeled channel began to meander, the stream bed aggraded and flow depth decreased markedly, creating a continuously connected, inter-reach complex of mid-channel bars. This study demonstrates the utility of using managed vegetations in stream corridor design and meander development, and it provides the practitioner with guidance on the magnitude of channel adjustment as it relates to vegetation density, shape, and spacing.

a Numerical Method for Stability Analysis of Pinned Flexible Mechanisms

NASA Astrophysics Data System (ADS)

Beale, D. G.; Lee, S. W.

1996-05-01

A technique is presented to investigate the stability of mechanisms with pin-jointed flexible members. The method relies on a special floating frame from which elastic link co-ordinates are defined. Energies are easily developed for use in a Lagrange equation formulation, leading to a set of non-linear and mixed ordinary differential-algebraic equations of motion with constraints. Stability and bifurcation analysis is handled using a numerical procedure (generalized co-ordinate partitioning) that avoids the tedious and difficult task of analytically reducing the system of equations to a number equalling the system degrees of freedom. The proposed method was then applied to (1) a slider-crank mechanism with a flexible connecting rod and crank of constant rotational speed, and (2) a four-bar linkage with a flexible coupler with a constant speed crank. In both cases, a single pinned-pinned beam bending mode is employed to develop resonance curves and stability boundaries in the crank length-crank speed parameter plane. Flip and fold bifurcations are common occurrences in both mechanisms. The accuracy of the proposed method was also verified by comparison with previous experimental results [1].

Preparation of Morpheus Vehicle for Vacuum Environment Testing

NASA Technical Reports Server (NTRS)

Sandoval, Armando

2016-01-01

The main objective for this summer 2016 tour was to prepare the Morpheus vehicle for its upcoming test inside Plum Brook's vacuum chamber at NASA John H. Glenn Research Center. My contributions towards this project were mostly analytical in nature, providing numerical models to validate test data, generating computer aided analyses for the structure support of the vehicle's engine, and designing a vacuum can that is to protect the high speed camera used during testing. Furthermore, I was also tasked with designing a tank toroidal spray bar system.

STS-57 inflight maintenance (IFM) tool tray at Boeing FEPF bench review

NASA Technical Reports Server (NTRS)

1993-01-01

STS-57 inflight maintenance (IFM) tool tray is displayed on a table top during the bench review at Boeing's Flight Equipment Processing Facility (FEPF) located near JSC. The tool tray will be located on Endeavour's, Orbiter Vehicle (OV) 105's, middeck in forward locker MF57K and includes pinch bar, deadblow hammer, punch, inspection mirror, speed handle assembly, robbins wrench, adjustable wrench, vise grips, connector pliers, ACCU bypass connector, connector strap wrench, locker tool, and mechanical fingers. Photo taken by NASA JSC contract photographer Benny Benavides.

The spinal control of locomotion and step-to-step variability in left-right symmetry from slow to moderate speeds

PubMed Central

Dambreville, Charline; Labarre, Audrey; Thibaudier, Yann; Hurteau, Marie-France

2015-01-01

When speed changes during locomotion, both temporal and spatial parameters of the pattern must adjust. Moreover, at slow speeds the step-to-step pattern becomes increasingly variable. The objectives of the present study were to assess if the spinal locomotor network adjusts both temporal and spatial parameters from slow to moderate stepping speeds and to determine if it contributes to step-to-step variability in left-right symmetry observed at slow speeds. To determine the role of the spinal locomotor network, the spinal cord of 6 adult cats was transected (spinalized) at low thoracic levels and the cats were trained to recover hindlimb locomotion. Cats were implanted with electrodes to chronically record electromyography (EMG) in several hindlimb muscles. Experiments began once a stable hindlimb locomotor pattern emerged. During experiments, EMG and bilateral video recordings were made during treadmill locomotion from 0.1 to 0.4 m/s in 0.05 m/s increments. Cycle and stance durations significantly decreased with increasing speed, whereas swing duration remained unaffected. Extensor burst duration significantly decreased with increasing speed, whereas sartorius burst duration remained unchanged. Stride length, step length, and the relative distance of the paw at stance offset significantly increased with increasing speed, whereas the relative distance at stance onset and both the temporal and spatial phasing between hindlimbs were unaffected. Both temporal and spatial step-to-step left-right asymmetry decreased with increasing speed. Therefore, the spinal cord is capable of adjusting both temporal and spatial parameters during treadmill locomotion, and it is responsible, at least in part, for the step-to-step variability in left-right symmetry observed at slow speeds. PMID:26084910

How to find the sedimentary archive of fluvial pollution in a bedrock-confined river reach

NASA Astrophysics Data System (ADS)

Elznicova, Jitka; Matys Grygar, Tomas; Kiss, Timea; Lelkova, Tereza; Balogh, Marton; Sikora, Martin

2016-04-01

The Ohre River springs in the Eastern Germany and it is a tributary of the Labe (Elbe) River in Northwest Bohemia. The river received pollution from several sources during the last five centuries. Most of the pollution sources located along the upper and middle reaches, where the depositional and erosional pattern of the river is highly variable. The upper part of the catchment consists of mainly felsic rocks and the river has a broad floodplain. The middle reach and its right-bank tributaries are deeply incised into the Doupovske Hory Mts., which consists of mafic volcanic rocks; whereas the left-bank tributaries are incised into intrusive and metamorphic rocks of the Krusne Hory Mts. (Ore mountains) with several local ore mines (Ag, Pb and U) in particular in around Olovi and Jachymov. Due to the geologic and geomorphologic complexity, deposition of historical sediments in the middle reach has been spatially limited and uneven, and anomalous background concentrations of risk elements are expected. As a consequence, in the middle reach of the Ohre River it is difficult to find a useful sedimentary archive of historical pollution, though it is desired for two main reasons: (1) to decipher the undocumented and poorly described pollution history from the Krusne Hory Mts. and (2) to better understand the retention of pollutants in the transport zones of a confined river system. Based on historical maps we identified a side-bar (35x320 m) in the middle reach of the river near Straz on Ohre and aimed to describe its formation, its recent erosion/deposition history and to evaluate its sedimentary archive value. In the first half of the 19th century it was an island separated from the valley edge by a side channel. Since then there has been no apparent lateral accretion of the bar (its shape has not been changed), but the upstream part of the side channel aggraded by a sediment plug. We evaluated the current bar topography and geomorphology by a detailed field survey, dated the sediments by dendrology and OSL dating, and performed in situ XRF analysis of sediment cores. The data show that the downstream head of the bar is the oldest and most of fine sediments (mostly sand, minor silt) of the bar material have been historically polluted by Pb mining. The sedimentary sequences, most valuable for reconstruction of recent pollution, were found in the side channel where the fill the representing the last ca 150 years pollution history (Hg and U). The body of the bar has been formed earlier. According to our hypothesis the bar originated as a direct consequence of historical mining in the nearby Jachymov Ore Region. The use of lateral fluvial deposits as a sedimentary archive definitely requires intensive application of fluvial geomorphology. Vice versa, pollution patterns will allow delineating areas, in particular the bar bank and inlet to the side channel, where intensive reworking (erosion/redeposition) occurred as documented by the microtopography and woody debris.

Changes in Kicking Pattern: Effect of Experience, Speed, Accuracy, and Effective Striking Mass

ERIC Educational Resources Information Center

Southard, Dan L.

2014-01-01

Purpose: The purposes of this study were to: (a) examine the effect of experience and goal constraints (speed, accuracy) on kicking patterns; (b) determine if effective striking mass was independent of ankle velocity at impact; and (c) determine the accuracy of kicks relative to independent factors. Method: Twenty participants were recruited to…

Hydrological regime as key to the morpho-texture and activity of braided streams

NASA Astrophysics Data System (ADS)

Storz-Peretz, Y.; Laronne, J. B.

2012-04-01

Braided streams are a common fluvial pattern in different climates. However, studies of gravel braided streams have mainly been conducted in humid braided systems or in flume simulations thereof, leaving arid braided streams scarcely investigated. Dryland rivers have bare catchments, rapid flow recession and unarmoured channel beds which are responsible for very high bedload discharges, thereby increasing the likelihood for braiding. Our main objective is to characterize the morpho-texture of the main morphological elements - mid-channel bars, chutes and anabranches (braid-cells) in the dryland braided system and compare them to their humid counterparts. Selected areas of the dryland braided Wadis Ze'elim, Rahaf and Roded in the SE hyper-arid Israel were measured, as were La-Bleone river in the French pre-alps along with the Saisera and Cimoliana rivers in NE Italy representing humid braided systems. Terrestrial Laser Scanning (TLS) of morphological units produced point clouds from which high resolution accurate Digital Elevation Models (DEMs) were extracted. Active braid cells in humid environments were also surveyed by electronic theodolite. Roughness and upper tail Grain Size Distribution (GSD) quantiles were derived from the scanned point clouds or from Wolman sampling. Results indicate that dryland anabranches tend to be finer-grained and less armoured than the bars, contrary to the humid braided systems, where the main or larger anabranches are coarser-grained and more armoured than the bars. Chutes are commonly similar or coarser-grained than the bars they dissect, in accordance with their steeper gradients due to the considerable relief of the bar-anabranch. The morpho-texture displayed in the steep braided Saisera River, located in the Italian Dolomites having the highest annual precipitation, has similarity to that of the dryland braided channels. In drylands coarse gravel is deposited mainly as bars due to the high flux of bedload, whereas the rapid flow recession is responsible for deposition of finer sediment with minimal winnowing in the branch channels. Therefore, channels are finer-grained than the bars. This process is associated with the mid-channel deposition of central bars. However, the steeper chutes and coarser anabranches are associated with erosive braiding processes, such as chute cutoffs and multiple bar dissection, allowing winnowing to occur also during rapid recession. Hence coarser-grained anabranches in drylands are essentially chutes. Lengthy flow recession in humid braided channels allows winnowing of fines, thereby generating armored channels, the finer sedimentary particles often deposited downstream as unit bars. Therefore, channels are coarser-grained than the bars they surround. Even though the steep Saisera is in a humid region, its hydrological regime is ephemeral with rapid and short recessions, responsible for a morpho-texture similar to that of dryland braided streams. Hence, the hydrologic regimen is a key to understanding the morpho-textural character of braided channels and for the higher activity of the ephemeral unarmoured channels in sub-barful events compared to their humid counterparts.

Preliminary assessment of channel stability and bed-material transport in the Tillamook Bay tributaries and Nehalem River basin, northwestern Oregon

USGS Publications Warehouse

Jones, Krista L.; Keith, Mackenzie K.; O'Connor, Jim E.; Mangano, Joseph F.; Wallick, J. Rose

2012-01-01

This report summarizes a preliminary study of bed-material transport, vertical and lateral channel changes, and existing datasets for the Tillamook (drainage area 156 square kilometers [km2]), Trask (451 km2), Wilson (500 km2), Kilchis (169 km2), Miami (94 km2), and Nehalem (2,207 km2) Rivers along the northwestern Oregon coast. This study, conducted in coopera-tion with the U.S. Army Corps of Engineers and Oregon Department of State Lands to inform permitting decisions regarding instream gravel mining, revealed that: * Study areas along the six rivers can be divided into reaches based on tidal influence and topography. The fluvial (nontidal or dominated by riverine processes) reaches vary in length (2.4-9.3 kilometer [km]), gradient (0.0011-0.0075 meter of elevation change per meter of channel length [m/m]), and bed-material composition (a mixture of alluvium and intermittent bedrock outcrops to predominately alluvium). In fluvial reaches, unit bar area (square meter of bar area per meter of channel length [m2/m]) as mapped from 2009 photographs ranged from 7.1 m2/m on the Tillamook River to 27.9 m2/m on the Miami River. * In tidal reaches, all six rivers flow over alluvial deposits, but have varying gradients (0.0001-0.0013 m/m) and lengths affected by tide (1.3-24.6 km). The Miami River has the steepest and shortest tidal reach and the Nehalem River has the flattest and longest tidal reach. Bars in the tidal reaches are generally composed of sand and mud. Unit bar area was greatest in the Tidal Nehalem Reach, where extensive mud flats flank the lower channel. * Background factors such as valley and channel confinement, basin geology, channel slope, and tidal extent control the spatial variation in the accumulation and texture of bed material. Presently, the Upper Fluvial Wilson and Miami Reaches and Fluvial Nehalem Reach have the greatest abundance of gravel bars, likely owing to local bed-material sources in combination with decreasing channel gradient and valley confinement. * Natural and human-caused disturbances such as mass movements, logging, fire, channel modifications for navigation and flood control, and gravel mining also have varying effects on channel condition, bed-material transport, and distribution and area of bars throughout the study areas and over time. * Existing datasets include at least 16 and 18 sets of aerial and orthophotographs that were taken of the study areas in the Tillamook Bay tributary basins and Nehalem River basin, respectively, from 1939 to 2011. These photographs are available for future assessments of long-term changes in channel condition, bar area, and vegetation establishment patterns. High resolution Light Detection And Ranging (LiDAR) surveys acquired in 2007-2009 could support future quantitative analyses of channel morphology and bed-material transport in all study areas. * A review of deposited and mined gravel volumes reported for instream gravel mining sites shows that bed-material deposition tends to rebuild mined bar surfaces in most years. Mean annual deposition volumes on individual bars exceeded 3,000 cubic meters (m3) on Donaldson Bar on the Wilson River, Dill Bar on the Kilchis River, and Plant and Winslow Bars on the Nehalem River. Cumulative reported volumes of bed-material deposition were greatest at Donaldson and Dill Bars, totaling over 25,000 m3 per site from 2004 to 2011. Within this period, reported cumulative mined volumes were greatest for the Donaldson, Plant, and Winslow Bars, ranging from 24,470 to 33,940 m3. * Analysis of historical stage-streamflow data collected by the U.S. Geological Survey on the Wilson River near Tillamook (14301500) and Nehalem River near Foss (14301000) shows that these rivers have episodically aggraded and incised, mostly following high flow events, but they do not exhibit systematic, long-term trends in bed elevation. * Multiple cross sections show that channels near bridge crossings in all six study areas are dynamic with many subject to incision and aggradation as well as lateral shifts in thalweg position and bank deposition and erosion. * In fluvial reaches, unit bar area declined a net 5.3-83.6 percent from 1939 to 2009. The documented reduction in bar area may be attributable to several factors, including vegetation establishment and stabilization of formerly active bar surfaces, lateral channel changes and resulting alterations in sediment deposition and erosion patterns, and streamflow and/or tide differences between photographs. Other factors that may be associated with the observed reduction in bar area but not assessed in this reconnaissance level study include changes in the sediment and hydrology regimes of these rivers over the analysis period. * In tidal reaches, unit bar area increased on the Tillamook and Nehalem Rivers (98.0 and 14.7 percent, respectively), but declined a net 24.2 to 83.1 percent in the other four tidal reaches. Net increases in bar area in the Tidal Tillamook and Nehalem Reaches were possibly attributable to tidal differences between the photographs as well as sediment deposition behind log booms and pile structures on the Tillamook River between 1939 and 1967. * The armoring ratio (ratio of the median grain sizes of a bar's surface and subsurface layers) was 1.6 at Lower Waldron Bar on the Miami River, tentatively indicating a relative balance between transport capacity and sediment supply at this location. Armoring ratios, however, ranged from 2.4 to 5.5 at sites on the Trask, Wilson, Kilchis, and Nehalem Rivers; these coarse armor layers probably reflect limited bed-material supply at these sites. * On the basis of mapping results, measured armoring ratios, and channel cross section surveys, preliminary conclusions are that the fluvial reaches on the Tillamook, Trask, Kilchis, and Nehalem Rivers are currently sediment supply-limited in terms of bed material - that is, the transport capacity of the channel generally exceeds the supply of bed material. The relation between transport capacity and sediment is more ambiguous for the fluvial reaches on the Wilson and Miami Rivers, but transport-limited conditions are likely for at least parts of these reaches. Some of these reaches have possibly evolved from sediment supply-limited to transport-limited over the last several decades in response to changing basin and climate conditions. * Because of exceedingly low gradients, all the tidal reaches are transport-limited. Bed material in these reaches, however, is primarily sand and finer grain-size material and probably transported as suspended load from upstream reaches. These reaches will be most susceptible to watershed conditions affecting the supply and transport of fine sediment. * Compared to basins on the southwestern Oregon coast, such as the Chetco and Rogue River basins, these six basins likely transport overall less gravel bed material. Although tentative in the absence of actual transport measurements, this conclusion is supported by the much lower area and frequency of bars and longer tidal reaches along all the northcoast rivers examined in this study. * Previous studies suggest that the expansive and largely unvegetated bars visible in the 1939 photographs are primarily associated with voluminous sedimentation starting soon after the first Tillamook Burn fire in 1933. However, USGS studies of temporal bar trends in other Oregon coastal rivers unaffected by the Tillamook Burn show similar declines in bar area over approximately the same analysis period. In the Umpqua and Chetco River basins, historical declines in bar area are associated with long-term decreases in flood magnitude. Other factors may include changes in the type and volume of large wood and riparian vegetation. Further characterization of hydrology patterns in these basins and possible linkages with climate factors related to flood peaks, such as the Pacific Decadal Oscillation, could support inferences of expected future changes in vegetation establishment and channel planform and profile. * More detailed investigations of bed-material transport rates and channel morphology would support assessments of lateral and vertical channel condition and longitudinal trends in bed material. Such assessments would be most practical for the fluvial study areas on the Wilson, Kilchis, Miami, and Nehalem Rivers and relevant to several ongoing management and ecological issues pertaining to sand and gravel transport. Tidal reaches may also be logical subjects for indepth analysis where studies would be more relevant to the deposition and transport of fine sediment (and associated channel and riparian conditions and processes) rather than coarse bed material.

An evaluation of the effects of handpiece speed, abrasive characteristics, and polishing load on the flexural strength of polished ceramics.

PubMed

Ahmad, Rohana; Morgano, Steven M; Wu, Benjamin M; Giordano, Russell A

2005-11-01

Many studies on the strengthening effects of grinding and polishing, as well as heat treatment on ceramics, are not well standardized or use commercially available industrial polishing systems. The reported effectiveness of these strengthening mechanisms on ceramics may not be applicable to clinical dentistry. The purpose of this study was to evaluate the effects of controlled polishing on the flexural strength of dental ceramics by using a custom-made machine that applied standardized loads and speeds that coincided with the mean loads and speeds used by experienced prosthodontists. A total of 140 aluminous dental ceramic bar-shaped specimens (Vitadur Alpha Enamel) measuring 1.5 x 2.0 x 25 mm were fabricated and divided into 12 groups (for most groups, n=10). Specimens were untreated, polished with different polishing systems, polished at different speeds, ground and autoglazed, polished and autoglazed, autoglazed and polished, polished with loose (paste) and bonded abrasives, or overglazed. Simulated clinical polishing was performed on the ceramic specimens by using a customized polishing apparatus that allowed independent control over the relevant polishing parameters (abrasive hardness, applied load, linear speed, rotational velocity, and wheel stiffness). Flexural strength (MPa) was measured with a 4-point bending test, and subjective surface roughness was assessed with scanning electron microscopy. Autoglazing was performed at various stages of the polishing sequence to determine the effects of polishing on surface stresses. Mean values, standard deviations, independent-sample t tests, 1-way and 2-way analyses of variance, Dunnett t tests and Kruskal-Wallis tests were applied to the data (alpha=.05). Under a clinical load of 0.6 N for a coarse polishing wheel, 1.0 N for a medium polishing wheel, and 1.3 N for a fine polishing wheel, a linear speed of 499 mm/min, and a rotational velocity of 10,000 rpm, the use of clinical polishing instruments did not affect the flexural strength of the aluminous ceramics studied (P=.274). At higher rotational velocity (20,000 rpm), specimens polished with the diamond polishing system produced statistically weaker specimens compared with those that had been polished at 10,000 rpm (P=.019). Autoglazing treatment of the diamond-polished specimens did not reverse the strength degradation (P=.125). Conversely, diamond polishing of the autoglazed specimens resulted in significant flexural strength reduction (P=.029). Fine-diamond-bonded abrasive significantly reduced flexural strength (P=.025). Simulated clinical polishing at 10,000 rpm did not appear to substantially strengthen or weaken the ceramic specimens. Polishing at 20,000 rpm reduced flexural strength of the ceramic bars.

Propositions for the Analysis of Commutation Phenomena and Modeling of Universal Motors Using the State Function Method

NASA Astrophysics Data System (ADS)

Niwa, Yuta; Akiyama, Yuji; Naruta, Tomokazu

We carried out FEM simulations for modeling ultra-high-speed universal motors by using the state function method and analyzed the phenomenon of commutator sparking, the characteristics of the air gap surface, and the contact condition or contact resistance of the brushes and commutator bars. Thus, we could quantitatively analyze commutator sparking and investigate the configuration of the iron core. The results of FEM analysis were used to develop a model for predicting the configuration of the iron core and for estimating the electromotive force generated by the transformer, armature reaction field, spark voltage, contact resistance between the rotating brushes, and changes in the gap permeance. The results of our simulation were experimental results. This confirmed the validity of our analysis method. Thus, an ultra-high-speed, high-capacity of 1.5kw motor rotating at 30,000rpm can be designed for use in vacuum cleaners.

WHERE THE INDIVIDUAL MEETS THE ECOLOGICAL: A STUDY OF PARENT DRINKING PATTERNS, ALCOHOL OUTLETS AND CHILD PHYSICAL ABUSE

PubMed Central

Freisthler, Bridget; Gruenewald, Paul J.

2012-01-01

Background Despite well-known associations between heavy drinking and child physical abuse, little is known about specific risks related to drinking different amounts of alcohol in different drinking venues. This study uses a context specific dose-response model to examine how drinking in various venues (e.g., at bars or parties) are related to physically abusive parenting practices while controlling for individual and psychosocial characteristics. Methods Data were collected via a telephone survey of parents in 50 cities in California resulting in 2,163 respondents who reported drinking in the past year. Child physical abuse and corporal punishment were measured using the Conflict Tactics Scale, Parent Child version. Drinking behaviors were measured using continued drinking measures. Data were analyzed using zero inflated Poisson models. Results Drinking at homes, parties or bars more frequently was related to greater frequencies of physically abusive parenting practices. The use of greater amounts of alcohol in association with drinking at bars appeared to increase risks for corporal punishment, a dose-response effect. Dose-response relationships were not found for drinking at homes or parties or drinking at bars for physical abuse nor for drinking at home and parties for corporal punishment. Conclusion Frequencies of using drinking venues, particularly bars and home or parties, are associated with greater use of abusive parenting practices. These findings suggest that a parent’s routine drinking activities place children at different risks for being physically abused. They also suggest that interventions that take into account parents’ alcohol use at drinking venues are an important avenue for secondary prevention efforts. PMID:23316780

Development of Multi-Physics Dynamics Models for High-Frequency Large-Amplitude Structural Response Simulation

NASA Technical Reports Server (NTRS)

Derkevorkian, Armen; Peterson, Lee; Kolaini, Ali R.; Hendricks, Terry J.; Nesmith, Bill J.

2016-01-01

An analytic approach is demonstrated to reveal potential pyroshock -driven dynamic effects causing power losses in the Thermo -Electric (TE) module bars of the Mars Science Laboratory (MSL) Multi -Mission Radioisotope Thermoelectric Generator (MMRTG). This study utilizes high- fidelity finite element analysis with SIERRA/PRESTO codes to estimate wave propagation effects due to large -amplitude suddenly -applied pyro shock loads in the MMRTG. A high fidelity model of the TE module bar was created with approximately 30 million degrees -of-freedom (DOF). First, a quasi -static preload was applied on top of the TE module bar, then transient tri- axial acceleration inputs were simultaneously applied on the preloaded module. The applied input acceleration signals were measured during MMRTG shock qualification tests performed at the Jet Propulsion Laboratory. An explicit finite element solver in the SIERRA/PRESTO computational environment, along with a 3000 processor parallel super -computing framework at NASA -AMES, was used for the simulation. The simulation results were investigated both qualitatively and quantitatively. The predicted shock wave propagation results provide detailed structural responses throughout the TE module bar, and key insights into the dynamic response (i.e., loads, displacements, accelerations) of critical internal spring/piston compression systems, TE materials, and internal component interfaces in the MMRTG TE module bar. They also provide confidence on the viability of this high -fidelity modeling scheme to accurately predict shock wave propagation patterns within complex structures. This analytic approach is envisioned for modeling shock sensitive hardware susceptible to intense shock environments positioned near shock separation devices in modern space vehicles and systems.

Drivers and seasonal predictability of extreme wind speeds in the ECMWF System 4 and a statistical model

NASA Astrophysics Data System (ADS)

Walz, M. A.; Donat, M.; Leckebusch, G. C.

2017-12-01

As extreme wind speeds are responsible for large socio-economic losses in Europe, a skillful prediction would be of great benefit for disaster prevention as well as for the actuarial community. Here we evaluate patterns of large-scale atmospheric variability and the seasonal predictability of extreme wind speeds (e.g. >95th percentile) in the European domain in the dynamical seasonal forecast system ECMWF System 4, and compare to the predictability based on a statistical prediction model. The dominant patterns of atmospheric variability show distinct differences between reanalysis and ECMWF System 4, with most patterns in System 4 extended downstream in comparison to ERA-Interim. The dissimilar manifestations of the patterns within the two models lead to substantially different drivers associated with the occurrence of extreme winds in the respective model. While the ECMWF System 4 is shown to provide some predictive power over Scandinavia and the eastern Atlantic, only very few grid cells in the European domain have significant correlations for extreme wind speeds in System 4 compared to ERA-Interim. In contrast, a statistical model predicts extreme wind speeds during boreal winter in better agreement with the observations. Our results suggest that System 4 does not seem to capture the potential predictability of extreme winds that exists in the real world, and therefore fails to provide reliable seasonal predictions for lead months 2-4. This is likely related to the unrealistic representation of large-scale patterns of atmospheric variability. Hence our study points to potential improvements of dynamical prediction skill by improving the simulation of large-scale atmospheric dynamics.

75 FR 16227 - Reports, Forms, and Record Keeping Requirements

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-31

... following proposed collection of information: Title: Motivations for Speeding. Type of Request: New... participants to examine driving speed patterns with the goals of understanding motivations for speeding. Based... data relevant to descriptions of key motivations, attitudes, normative commitment to law, driving...

An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses.

PubMed

Hobbs, Sarah Jane; Bertram, John E A; Clayton, Hilary M

2016-01-01

Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001) from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04) through synchronous (0.36 ± 0.02) to a more cranial location in fore-first dissociation (0.32 ± 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R = .594; P < .01) and speed (R = .789; P < .01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R = .085; P > 0.05) or speed (R = .223; P = .023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

History of river regulation of the Noce River (NE Italy) and related bio-morphodynamic responses

NASA Astrophysics Data System (ADS)

Serlet, Alyssa; Scorpio, Vittoria; Mastronunzio, Marco; Proto, Matteo; Zen, Simone; Zolezzi, Guido; Bertoldi, Walter; Comiti, Francesco; Prà, Elena Dai; Surian, Nicola; Gurnell, Angela

2016-04-01

The Noce River is a hydropower-regulated Alpine stream in Northern-East Italy and a major tributary of the Adige River, the second longest Italian river. The objective of the research is to investigate the response of the lower course of the Noce to two main stages of hydromorphological regulation; channelization/ diversion and, one century later, hydropower regulation. This research uses a historical reconstruction to link the geomorphic response with natural and human-induced factors by identifying morphological and vegetation features from historical maps and airborne photogrammetry and implementing a quantitative analysis of the river response to channelization and flow / sediment supply regulation related to hydropower development. A descriptive overview is presented. The concept of evolutionary trajectory is integrated with predictions from morphodynamic theories for river bars that allow increased insight to investigate the river response to a complex sequence of regulatory events such as development of bars, islands and riparian vegetation. Until the mid-19th century the river had a multi-thread channel pattern. Thereafter (1852) the river was straightened and diverted. Upstream of Mezzolombardo village the river was constrained between embankments of approximately 100 m width while downstream they are of approximately 50 m width. Since channelization some interesting geomorphic changes have appeared in the river e.g. the appearance of alternate bars in the channel. In 1926 there was a breach in the right bank of the downstream part that resulted in a multi-thread river reach which can be viewed as a recovery to the earlier multi-thread pattern. After the 1950's the flow and sediment supply became strongly regulated by hydropower development. The analysis of aerial images reveals that the multi-thread reach became progressively stabilized by vegetation development over the bars, though signs of some dynamics can still be recognizable today, despite the strong hydropeaking that dominates the flow regime. The results of the historical analysis will be used in a larger framework that focuses on interdisciplinary research of interactions between flow, sediment and vegetation in regulated rivers and aims to enhance knowledge on the interplay between river bars and vegetation in the perspective of providing enhanced tools for river rehabilitation and restoration.

Rats' Anticipation of Current and Future Trial Outcomes in the Ordered RNR/RNN Serial Pattern Task

ERIC Educational Resources Information Center

Cohen, Jerome; Mohamoud, Sirad; Szelest, Izabela; Kani, Tammy

2008-01-01

In the ordered RNR/RNN serial pattern task, rats often reduce their running speeds on trial 2 less within the RNR than within the RNN series. Initially, investigators (Capaldi, 1985; Capaldi et al., 1983) considered this trial 2 differential speed effect evidence for rats' anticipation of inter-trial outcomes within each series. Later findings,…

Noninterference Systems Developed for Measuring and Monitoring Rotor Blade Vibrations

NASA Technical Reports Server (NTRS)

Kurkov, Anatole P.

2003-01-01

In the noninterference measurement of blade vibrations, a laser light beam is transmitted to the rotor blade tips through a single optical fiber, and the reflected light from the blade tips is collected by a receiving fiber-optic bundle and conducted to a photodetector. Transmitting and receiving fibers are integrated in an optical probe that is enclosed in a metal tube which also houses a miniature lens that focuses light on the blade tips. Vibratory blade amplitudes can be deduced from the measurement of the instantaneous time of arrival of the blades and the knowledge of the rotor speed. The in-house noninterference blade-vibration measurement system was developed in response to requirements to monitor blade vibrations in several tests where conventional strain gauges could not be installed or where there was a need to back up strain gauges should critical gauges fail during the test. These types of measurements are also performed in the aircraft engine industry using proprietary in-house technology. Two methods of measurement were developed for vibrations that are synchronous with a rotor shaft. One method requires only one sensor; however, it is necessary to continuously record the data while the rotor is being swept through the resonance. In the other method, typically four sensors are employed and the vibratory amplitude is deduced from the data by performing a least square fit to a harmonic function. This method does not require continuous recording of data through the resonance and, therefore, is better suited for monitoring. The single-probe method was tested in the Carl facility at the Wright- Patterson Air Force Base, and the multiple-probe method was tested in NASA Glenn Research Center's Spin Rig facility, which uses permanent magnets to excite synchronous vibrations. Representative results from this test are illustrated in the bar chart. Nonsynchronous vibrations were measured online during testing of the Quiet High Speed Fan in Glenn s 9- by 15-Foot Low-Speed Wind Tunnel. Three sensors were employed, enabling a reconstruction of the vibratory patterns at the leading and trailing edges at the tip span, as well as a determination of vibratory amplitudes for every blade.

Different propagation speeds of recalled sequences in plastic spiking neural networks

NASA Astrophysics Data System (ADS)

Huang, Xuhui; Zheng, Zhigang; Hu, Gang; Wu, Si; Rasch, Malte J.

2015-03-01

Neural networks can generate spatiotemporal patterns of spike activity. Sequential activity learning and retrieval have been observed in many brain areas, and e.g. is crucial for coding of episodic memory in the hippocampus or generating temporal patterns during song production in birds. In a recent study, a sequential activity pattern was directly entrained onto the neural activity of the primary visual cortex (V1) of rats and subsequently successfully recalled by a local and transient trigger. It was observed that the speed of activity propagation in coordinates of the retinotopically organized neural tissue was constant during retrieval regardless how the speed of light stimulation sweeping across the visual field during training was varied. It is well known that spike-timing dependent plasticity (STDP) is a potential mechanism for embedding temporal sequences into neural network activity. How training and retrieval speeds relate to each other and how network and learning parameters influence retrieval speeds, however, is not well described. We here theoretically analyze sequential activity learning and retrieval in a recurrent neural network with realistic synaptic short-term dynamics and STDP. Testing multiple STDP rules, we confirm that sequence learning can be achieved by STDP. However, we found that a multiplicative nearest-neighbor (NN) weight update rule generated weight distributions and recall activities that best matched the experiments in V1. Using network simulations and mean-field analysis, we further investigated the learning mechanisms and the influence of network parameters on recall speeds. Our analysis suggests that a multiplicative STDP rule with dominant NN spike interaction might be implemented in V1 since recall speed was almost constant in an NMDA-dominant regime. Interestingly, in an AMPA-dominant regime, neural circuits might exhibit recall speeds that instead follow the change in stimulus speeds. This prediction could be tested in experiments.

Linear hypergeneralization of learned dynamics across movement speeds reveals anisotropic, gain-encoding primitives for motor adaptation.

PubMed

Joiner, Wilsaan M; Ajayi, Obafunso; Sing, Gary C; Smith, Maurice A

2011-01-01

The ability to generalize learned motor actions to new contexts is a key feature of the motor system. For example, the ability to ride a bicycle or swing a racket is often first developed at lower speeds and later applied to faster velocities. A number of previous studies have examined the generalization of motor adaptation across movement directions and found that the learned adaptation decays in a pattern consistent with the existence of motor primitives that display narrow Gaussian tuning. However, few studies have examined the generalization of motor adaptation across movement speeds. Following adaptation to linear velocity-dependent dynamics during point-to-point reaching arm movements at one speed, we tested the ability of subjects to transfer this adaptation to short-duration higher-speed movements aimed at the same target. We found near-perfect linear extrapolation of the trained adaptation with respect to both the magnitude and the time course of the velocity profiles associated with the high-speed movements: a 69% increase in movement speed corresponded to a 74% extrapolation of the trained adaptation. The close match between the increase in movement speed and the corresponding increase in adaptation beyond what was trained indicates linear hypergeneralization. Computational modeling shows that this pattern of linear hypergeneralization across movement speeds is not compatible with previous models of adaptation in which motor primitives display isotropic Gaussian tuning of motor output around their preferred velocities. Instead, we show that this generalization pattern indicates that the primitives involved in the adaptation to viscous dynamics display anisotropic tuning in velocity space and encode the gain between motor output and motion state rather than motor output itself.

The influence of cutting speed and cutting initiation location in specimen preparation for the microtensile bond strength test.

PubMed

Abreu, Celina Wanderley; Santosb, Jarbas F; Passos, Sheila Pestana; Michida, Silvia Masae; Takahashi, Fernando Eidi; Bottino, Marco Antonio

2011-06-01

This study evaluated the effect of cutting initiation location and cutting speed on the bond strength between resin cement and feldspathic ceramic. Thirty-six blocks (6.4 x 6.4 x 4.8 mm) of ceramic (Vita VM7) were produced. The ceramic surfaces were etched with 10% hydrofluoric acid gel for 60 s and then silanized. Each ceramic block was placed in a silicon mold with the treated surface exposed. A resin cement (Variolink II) was injected into the mold over the treated surface and polymerized. The resin cement-ceramic blocks were divided into two groups according to experimental conditions: a) cutting initiation location - resin cement, ceramic and interface; and b) cutting speed - 10,000, 15,000, and 20,000 rpm. The specimens were sectioned to achieve non-trimmed bar specimens. The microtensile test was performed in a universal testing machine (1 mm/min). The failure modes were examined using an optical light microscope and SEM. Bond strength results were analyzed using one-way ANOVA and Tukey's test (α = 0.05). Significant influences of cutting speed and initiation location on bond strength (p < 0.05) were observed. The highest mean was achieved for specimens cut at 15,000 rpm at the interface (15.12 ± 5.36 MPa). The lowest means were obtained for specimens cut at the highest cutting speed in resin cement (8.50 ± 3.27 MPa), and cut at the lowest cutting speed in ceramic (8.60 ± 2.65 MPa). All groups showed mainly mixed failure (75% to 100%). The cutting speed and initiation location are important factors that should be considered during specimen preparation for microtensile bond strength testing, as both may influence the bond strength results.

Visual control of flight speed in Drosophila melanogaster.

PubMed

Fry, Steven N; Rohrseitz, Nicola; Straw, Andrew D; Dickinson, Michael H

2009-04-01

Flight control in insects depends on self-induced image motion (optic flow), which the visual system must process to generate appropriate corrective steering maneuvers. Classic experiments in tethered insects applied rigorous system identification techniques for the analysis of turning reactions in the presence of rotating pattern stimuli delivered in open-loop. However, the functional relevance of these measurements for visual free-flight control remains equivocal due to the largely unknown effects of the highly constrained experimental conditions. To perform a systems analysis of the visual flight speed response under free-flight conditions, we implemented a 'one-parameter open-loop' paradigm using 'TrackFly' in a wind tunnel equipped with real-time tracking and virtual reality display technology. Upwind flying flies were stimulated with sine gratings of varying temporal and spatial frequencies, and the resulting speed responses were measured from the resulting flight speed reactions. To control flight speed, the visual system of the fruit fly extracts linear pattern velocity robustly over a broad range of spatio-temporal frequencies. The speed signal is used for a proportional control of flight speed within locomotor limits. The extraction of pattern velocity over a broad spatio-temporal frequency range may require more sophisticated motion processing mechanisms than those identified in flies so far. In Drosophila, the neuromotor pathways underlying flight speed control may be suitably explored by applying advanced genetic techniques, for which our data can serve as a baseline. Finally, the high-level control principles identified in the fly can be meaningfully transferred into a robotic context, such as for the robust and efficient control of autonomous flying micro air vehicles.

Measurement of instantaneous rotational speed using double-sine-varying-density fringe pattern

NASA Astrophysics Data System (ADS)

Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Peng, Zhike

2018-03-01

Fast and accurate rotational speed measurement is required both for condition monitoring and faults diagnose of rotating machineries. A vision- and fringe pattern-based rotational speed measurement system was proposed to measure the instantaneous rotational speed (IRS) with high accuracy and reliability. A special double-sine-varying-density fringe pattern (DSVD-FP) was designed and pasted around the shaft surface completely and worked as primary angular sensor. The rotational angle could be correctly obtained from the left and right fringe period densities (FPDs) of the DSVD-FP image sequence recorded by a high-speed camera. The instantaneous angular speed (IAS) between two adjacent frames could be calculated from the real-time rotational angle curves, thus, the IRS also could be obtained accurately and efficiently. Both the measurement principle and system design of the novel method have been presented. The influence factors on the sensing characteristics and measurement accuracy of the novel system, including the spectral centrobaric correction method (SCCM) on the FPD calculation, the noise sources introduce by the image sensor, the exposure time and the vibration of the shaft, were investigated through simulations and experiments. The sampling rate of the high speed camera could be up to 5000 Hz, thus, the measurement becomes very fast and the change in rotational speed was sensed within 0.2 ms. The experimental results for different IRS measurements and characterization of the response property of a servo motor demonstrated the high accuracy and fast measurement of the proposed technique, making it attractive for condition monitoring and faults diagnosis of rotating machineries.

Changes in planform geomorphology and vegetation of the Umatilla River during a 50-year period of diminishing peak flow

NASA Astrophysics Data System (ADS)

Hughes, M. L.; McDowell, P. F.

2017-12-01

The Umatilla River of northeastern Oregon is a gravel-bedded, mixed pattern, salmonid-bearing channel-floodplain system typical of the Interior Columbia River Basin. Efforts to restore native salmonids in this region since the 1980's coupled with increased scrutiny of flood- and erosion-control activities have prompted a need for better understanding of the biogemorphic implications of flood disturbances. The goals of this study are: (1) to re-examine results of earlier studies of flood impacts on the Umatilla River in light of more recent flow records, and (2) to investigate the degree to which large floods have influenced existing patterns of channel-floodplain geomorphology and vegetation. Mapping of flowing channels, bars, scoured surfaces, and vegetation within the active channel from of aerial photos bracketing flood and inter-flood periods since 1964 indicates complex and spatially variable channel changes. In general, channel scour was the most consistent response to flooding. The direction (gain/loss) and magnitude of changes in bars and vegetation within the active channel, as well as the amount of lateral channel movement and changes in sinuosity, were generally inconsistent across flood events. The removal of vegetation by scour during floods was in many areas compensated by the capture of vegetation from the floodplain by avulsion and activation of secondary channels. To date, the geomorphic impacts of the 1964-65 flood-of-record have not been replicated, despite an overall increase in the frequency of smaller floods. Expansion of riparian vegetation in recent decades has mainly occurred in areas disturbed by scour and bar deposition during the 1964-65 floods. Vegetative succession during this period has caused contraction of the active channel such that it now appears much as it did before the 1964-65 floods. These results underscore the importance of large floods as drivers of biogeormphic processes and patterns over timescales relevant to river management and restoration.

Shear wave speed and dispersion measurements using crawling wave chirps.

PubMed

Hah, Zaegyoo; Partin, Alexander; Parker, Kevin J

2014-10-01

This article demonstrates the measurement of shear wave speed and shear speed dispersion of biomaterials using a chirp signal that launches waves over a range of frequencies. A biomaterial is vibrated by two vibration sources that generate shear waves inside the medium, which is scanned by an ultrasound imaging system. Doppler processing of the acquired signal produces an image of the square of vibration amplitude that shows repetitive constructive and destructive interference patterns called "crawling waves." With a chirp vibration signal, successive Doppler frames are generated from different source frequencies. Collected frames generate a distinctive pattern which is used to calculate the shear speed and shear speed dispersion. A special reciprocal chirp is designed such that the equi-phase lines of a motion slice image are straight lines. Detailed analysis is provided to generate a closed-form solution for calculating the shear wave speed and the dispersion. Also several phantoms and an ex vivo human liver sample are scanned and the estimation results are presented. © The Author(s) 2014.

A Qualitative Exploration of the Effects of Increasing the Minimum Purchase Age of Alcohol in Thailand

PubMed Central

Srirojn, Bangorn; Lilleston, Pam; Aramrattana, Apinun; Thomson, Nicholas; Celentano, David D.; Sherman, Susan G.

2015-01-01

Introduction and Aims Although prevalence of alcohol consumption has been relatively stable among Thai youth, concerns over alcohol-related harms affecting youth influenced the passage of new laws in early 2008, which made it illegal to sell alcohol to anyone under the age of 20. This qualitative study explored the effects of the law on the purchasing patterns of underage Thai bar patrons, in order to understand the strategies employed by underage youth to circumvent the law. Design and Methods A total of 41 in-depth interviews were conducted with 18–19 year old bar patrons in Chiang Mai, Thailand. Results Underage Thai bar patrons frequented shops where enforcement was not strict and purchased alcohol, from familiar shopkeepers in their neighborhoods. Participants suggested that purchasing alcohol was relatively easy as long as shopkeepers were driven by the need to make a profit. Discussion and Conclusions To address alcohol-related harms, the control law must be enforced in a meaningful way to deter youth from purchasing alcohol. Otherwise, the law will have minimal effectiveness in reducing the harms associated with alcohol. PMID:22762793

Economy and rate of carbohydrate oxidation during running with rearfoot and forefoot strike patterns.

PubMed

Gruber, Allison H; Umberger, Brian R; Braun, Barry; Hamill, Joseph

2013-07-15

It continues to be argued that a forefoot (FF) strike pattern during running is more economical than a rearfoot (RF) pattern; however, previous studies using one habitual footstrike group have found no difference in running economy between footstrike patterns. We aimed to conduct a more extensive study by including both habitual RF and FF runners. The purposes of this study were to determine whether there were differences in running economy between these groups and whether running economy would change when they ran with the alternative footstrike pattern. Nineteen habitual RF and 18 habitual FF runners performed the RF and FF patterns on a treadmill at 3.0, 3.5, and 4.0 m/s. Steady-state rates of oxygen consumption (Vo2, ml·kg(-1)·min(-1)) and carbohydrate contribution to total energy expenditure (%CHO) were determined by indirect calorimetry for each footstrike pattern and speed condition. A mixed-model ANOVA was used to assess the differences in each variable between groups and footstrike patterns (α = 0.05). No differences in Vo2 or %CHO were detected between groups when running with their habitual footstrike pattern. The RF pattern resulted in lower Vo2 and %CHO compared with the FF pattern at the slow and medium speeds in the RF group (P < 0.05) but not in the FF group (P > 0.05). At the fast speed, a significant footstrike pattern main effect indicated that Vo2 was greater with the FF pattern than with the RF pattern (P < 0.05), but %CHO was not different (P > 0.05). The results suggest that the FF pattern is not more economical than the RF pattern.

Electrical Field Guided Electrospray Deposition for Production of Gradient Particle Patterns.

PubMed

Yan, Wei-Cheng; Xie, Jingwei; Wang, Chi-Hwa

2018-06-06

Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

Difference in muscle activation patterns during high-speed versus standard-speed yoga: A randomized sequence crossover study.

PubMed

Potiaumpai, Melanie; Martins, Maria Carolina Massoni; Wong, Claudia; Desai, Trusha; Rodriguez, Roberto; Mooney, Kiersten; Signorile, Joseph F

2017-02-01

To compare the difference in muscle activation between high-speed yoga and standard-speed yoga and to compare muscle activation of the transitions between poses and the held phases of a yoga pose. Randomized sequence crossover trial SETTING: A laboratory of neuromuscular research and active aging Interventions: Eight minutes of continuous Sun Salutation B was performed, at a high speed versus a standard-speed, separately. Electromyography was used to quantify normalized muscle activation patterns of eight upper and lower body muscles (pectoralis major, medial deltoids, lateral head of the triceps, middle fibers of the trapezius, vastus medialis, medial gastrocnemius, thoracic extensor spinae, and external obliques) during the high-speed and standard-speed yoga protocols. Difference in normalized muscle activation between high-speed yoga and standard-speed yoga. Normalized muscle activity signals were significantly higher in all eight muscles during the transition phases of poses compared to the held phases (p<0.01). There was no significant interaction between speed×phase; however, greater normalized muscle activity was seen for highspeed yoga across the entire session. Our results show that transitions from one held phase of a pose to another produces higher normalized muscle activity than the held phases of the poses and that overall activity is greater during highspeed yoga than standard-speed yoga. Therefore, the transition speed and associated number of poses should be considered when targeting specific improvements in performance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bar workers' exposure to second-hand smoke: the effect of Scottish smoke-free legislation on occupational exposure.

PubMed

Semple, Sean; Maccalman, Laura; Naji, Audrey Atherton; Dempsey, Scott; Hilton, Shona; Miller, Brian G; Ayres, Jon G

2007-10-01

To examine changes in bar workers' exposure to second-hand smoke (SHS) over a 12-month period before and after the introduction of Scottish smoke-free legislation on the 26 March 2006. A total of 371 bar workers were recruited from 72 bars in three cities: Aberdeen, Glasgow, Edinburgh and small towns in two rural regions (Borders and Aberdeenshire). Prior to the introduction of the smoke-free legislation, we visited all participants in their place of work and collected saliva samples, for the measurement of cotinine, together with details on work patterns, self-reported exposure to SHS at work and non-work settings and smoking history. This was repeated 2 months post-legislation and again in the spring of 2007. In addition, we gathered full-shift personal exposure data from a small number of Aberdeen bar workers using a personal aerosol monitor for fine particulate matter (PM(2.5)) at the baseline and 2 months post-legislation visits. Data were available for 371 participants at baseline, 266 (72%) at 2 months post-legislation and 191 (51%) at the 1-year follow-up. The salivary cotinine level recorded in non-smokers fell from a geometric mean of 2.94 ng ml(-1) prior to introduction of the legislation to 0.41 ng ml(-1) at 1-year follow-up. Paired data showed a reduction in non-smokers' cotinine levels of 89% [95% confidence interval (CI) 85-92%]. For the whole cohort, the duration of workplace exposure to SHS within the last 7 days fell from 28.5 to 0.83 h, though some bar workers continued to report substantial SHS exposures at work despite the legislation. Smokers also demonstrated reductions in their salivary cotinine levels of 12% (95% CI 3-20%). This may reflect both the reduction in SHS exposure at work and falls in active cigarette smoking in this group. In a small sub-sample of bar workers, full-shift personal exposure to PM(2.5), a marker of SHS concentrations, showed average reductions of 86% between baseline and 2 months after implementation of the legislation. Most bar workers have experienced very large reductions in their workplace exposure to SHS as a result of smoke-free legislation in Scotland. These reductions have been sustained over a period of 1 year.

Dispersion effects in the miscible displacement of two fluids in a duct of large aspect ratio

NASA Astrophysics Data System (ADS)

Zhang, J.; Frigaard, I. A.

We study miscible displacements in long ducts in the dispersive limit of small \\varepsilon Pe, where \\varepsilon ≪ 1 is the inverse aspect ratio and Pe the Péclet number. We consider the class of generalized Newtonian fluids, with specified closure laws for the fluid properties of the concentration-dependent mixture. Regardless of viscosity ratio and the constitutive laws of the pure fluids, for sufficiently small \\varepsilon Pe these displacements are characterized by rapid cross-stream diffusion and slow streamwise dispersion, i.e. the concentration appears to be near-uniform across the duct and spreads slowly as it translates. Using the multiple-scales method we derive the leading-order asymptotic approximation to the average fluid concentration bar{c}_0. We show that bar{c}_0 evolves on the slow timescale t ˜ (\\varepsilon Pe)^{-1}, and satisfies a nonlinear diffusion equation in a frame of reference moving with the mean speed of the flow. In the case that the two fluids have identical rheologies and the concentration represents a passive tracer, the diffusion equation is linear. For Newtonian fluids we recover the classical results of Taylor (l953), Aris (1956), and for power-law fluids those of Vartuli et al. (1995). In the case that the fluids differ and/or that mixing is non-passive, bar{c}_0 satisfies a nonlinear diffusion equation in the moving frame of reference. Given a specific mixing/closure law for the rheological properties, we are able to compute the dispersive diffusivity D_T(bar{c}_0) and predict spreading along the channel. We show that D_T(bar{c}_0) can vary significantly with choice of mixing law and discuss why. This also opens the door to possibilities of controlling streamwise spreading by the rheological design of reactive mixtures, i.e. including chemical additives such that the rheology of the mixture behaves very differently to the rheology of either pure fluid. Computed examples illustrate the potential effects that might be achieved.

The linkage between fluvial meander-belt morphodynamics and the depositional record improves paleoenvironmental interpretations, Western Interior Basin, Alberta, Canada

NASA Astrophysics Data System (ADS)

Durkin, P.; Hubbard, S. M.

2016-12-01

Enhanced stratigraphic interpretations are possible when linkages between morphodynamic processes and the depositional record are resolved. Recent studies of modern and ancient meander-belt deposits have emphasized morphodynamic processes that are commonly understated in the analysis of stratigraphic products, such as intra-point bar erosion and rotation, counter-point-bar (concave bank-bench) development and meander-bend abandonment. On a larger scale, longitudinal changes in meander-belt morphology and processes such as changes in meander-bend migration rate, channel-belt width/depth ratio and sinuosity have been observed as rivers flow through the tidal backwater zone. However, few studies have attempted to recognize the impact of the backwater zone in the stratigraphic record. We consider ancient meander-belt deposits of the Cretaceous McMurray Formation and document linkages between morphodynamic processes and their stratigraphic product to resolve more detailed paleoenvironmental interpretations. The ancient meander belt was characterized by paleochannels that were 600 m wide and up to 50 m deep, resolved in a particularly high quality subsurface dataset consisting of 600 km2 of high-quality 3-D seismic data and over 1000 wellbores. A 3-D geocellular model and reconstructed paleochannel migration patterns reveal the evolutionary history of seventeen individual meander belt elements, including point bars, counter point bars and their associated abandoned channel fills. At the meander-bend scale, intra-point-bar erosion surfaces bound accretion packages characterized by unique accretion directions, internal stratigraphic architecture and lithologic properties. Erosion surfaces and punctuated bar rotation are linked to upstream changes in channel planform geometry (meander cut-offs). We provide evidence for downstream translation and development of counter-point bars that formed in response to valley-edge and intra-meander-belt confinement. At the meander-belt scale, analysis of changes in morphology over time reveal a decrease in channel-belt width/thickness ratio and sinuosity, which we attribute to the landward migration of the paleo-backwater limit due to the oncoming and overlying transgression of the Cretaceous Boreal Sea into the Western Interior Basin.

Local and regional effects of large scale atmospheric circulation patterns on winter wind power output in Western Europe

NASA Astrophysics Data System (ADS)

Zubiate, Laura; McDermott, Frank; Sweeney, Conor; O'Malley, Mark

2014-05-01

Recent studies (Brayshaw, 2009, Garcia-Bustamante, 2010, Garcia-Bustamante, 2013) have drawn attention to the sensitivity of wind speed distributions and likely wind energy power output in Western Europe to changes in low-frequency, large scale atmospheric circulation patterns such as the North Atlantic Oscillation (NAO). Wind speed variations and directional shifts as a function of the NAO state can be larger or smaller depending on the North Atlantic region that is considered. Wind speeds in Ireland and the UK for example are approximately 20 % higher during NAO + phases, and up to 30 % lower during NAO - phases relative to the long-term (30 year) climatological means. By contrast, in southern Europe, wind speeds are 15 % lower than average during NAO + phases and 15 % higher than average during NAO - phases. Crucially however, some regions such as Brittany in N.W. France have been identified in which there is negligible variability in wind speeds as a function of the NAO phase, as observed in the ERA-Interim 0.5 degree gridded reanalysis database. However, the magnitude of these effects on wind conditions is temporally and spatially non-stationary. As described by Comas-Bru and McDermott (2013) for temperature and precipitation, such non-stationarity is caused by the influence of two other patterns, the East Atlantic pattern, (EA), and the Scandinavian pattern, (SCA), which modulate the position of the NAO dipole. This phenomenon has also implications for wind speeds and directions, which has been assessed using the ERA-Interim reanalysis dataset and the indices obtained from the PC analysis of sea level pressure over the Atlantic region. In order to study the implications for power production, the interaction of the NAO and the other teleconnection patterns with local topography was also analysed, as well as how these interactions ultimately translate into wind power output. The objective is to have a better defined relationship between wind speed and power output at a local level and a tool that wind farm developers could use to inform site selection. A particular priority was to assess how the potential wind power outputs over a 25-30 year windfarm lifetime in less windy, but resource-stable regions, compare with those from windier but more variable sites.

Relationship between foot strike pattern, running speed, and footwear condition in recreational distance runners.

PubMed

Cheung, Roy T H; Wong, Rodney Y L; Chung, Tim K W; Choi, R T; Leung, Wendy W Y; Shek, Diana H Y

2017-06-01

Compared to competitive runners, recreational runners appear to be more prone to injuries, which have been associated with foot strike patterns. Surprisingly, only few studies had examined the foot strike patterns outside laboratories. Therefore, this study compared the foot strike patterns in recreational runners at outdoor tracks with previously reported data. We also investigated the relationship between foot strike pattern, speed, and footwear in this cohort. Among 434 recreational runners analysed, 89.6% of them landed with rearfoot strike (RFS). Only 6.9 and 3.5% landed with midfoot and forefoot, respectively. A significant shift towards non-RFS was observed in our cohort, when compared with previously reported data. When speed increased by 1 m/s, the odds of having forefoot strike and midfoot strike relative to RFS increased by 2.3 times and 2.6 times, respectively. Runners were 9.2 times more likely to run with a forefoot strike in minimalists compared to regular running shoes, although 70% of runners in minimalists continued to use a RFS. These findings suggest that foot strike pattern may differ across running conditions and runners should consider these factors in order to mitigate potential injury.

Epoxy-resin patterns speed shell-molding of aluminum parts

NASA Technical Reports Server (NTRS)

1965-01-01

Half patterns cast from commercial epoxy resin containing aluminum powder are used for shell-molding of aluminum parts. The half patterns are cast in plastic molds of the original wooden pattern. Ten serviceable sand resin molds are made from each epoxy pattern.

Expression of c-Fos in the rat retrosplenial cortex during instrumental re-learning of appetitive bar-pressing depends on the number of stages of previous training.

PubMed

Svarnik, Olga E; Bulava, Alexandra I; Alexandrov, Yuri I

2013-01-01

Learning is known to be accompanied by induction of c-Fos expression in cortical neurons. However, not all neurons are involved in this process. What the c-Fos expression pattern depends on is still unknown. In the present work we studied whether and to what degree previous animal experience about Task 1 (the first phase of an instrumental learning) influenced neuronal c-Fos expression in the retrosplenial cortex during acquisition of Task 2 (the second phase of an instrumental learning). Animals were progressively shaped across days to bar-press for food at the left side of the experimental chamber (Task 1). This appetitive bar-pressing behavior was shaped by nine stages ("9 stages" group), five stages ("5 stages" group) or one intermediate stage ("1 stage" group). After all animals acquired the first skill and practiced it for five days, the bar and feeder on the left, familiar side of the chamber were inactivated, and the animals were allowed to learn a similar instrumental task at the opposite side of the chamber using another pair of a bar and a feeder (Task 2). The highest number of c-Fos positive neurons was found in the retrosplenial cortex of "1 stage" animals as compared to the other groups. The number of c-Fos positive neurons in "5 stages" group animals was significantly lower than in "1 stage" animals and significantly higher than in "9 stages" animals. The number of c-Fos positive neurons in the cortex of "9 stages" animals was significantly higher than in home caged control animals. At the same time, there were no significant differences between groups in such behavioral variables as the number of entrees into the feeder or bar zones during Task 2 learning. Our results suggest that c-Fos expression in the retrosplenial cortex during Task 2 acquisition was influenced by the previous learning history.

The effects of annealing temperature on the structural properties and optical constants of a novel DPEA-MR-Zn organic crystalline semiconductor nanostructure thin films

NASA Astrophysics Data System (ADS)

Al-Hossainy, A. Farouk; Ibrahim, A.

2017-11-01

The dependence of structural properties and optical constants on annealing temperature of a 2-((1,2-bis (diphenylphosphino)ethyl)amino) acetic acid-methyl red-monochloro zinc dihydride (DPEA-MR-Zn) as a novel organic semiconductor thin film was studied. The DPEA-MR-Zn thin film was deposited on silicon substrates using the spin coating technique. The as-deposited film was annealed in air for 1 h at 150, 175 and 205 °C. The XRD study of DPEA-MR-Zn in its powder form showed that this complex is mere a triclinic crystal structure with a space group P-1. In addition, the XRD patterns showed that the as-deposited thin films were crystallized according to the preferential orientation [(214), (121), (0 2 bar 6), (3 bar 02), (122) and (11 4 bar)]. Moreover, two additional peaks (2 bar 2 bar 1 and 2 4 bar 7) were shown at 2θ nearly 30°, and 69°, where, the more annealing temperature, the more the intensity of the two peaks. In addition, it was noticed that the grain size had a remarkable change with an annealing temperature of the DPEA-MR-Zn thin films. The optical measurements showed that the thin film has a relatively high absorption region where the photon energy ranges from 2 to 3.25 eV. Both of Wemple-DiDomenico and single Sellmeier oscillator models were applied on the DPEA-MR-Zn to analyze the dispersion of the refractive index and the optical and dielectric constants. The outcome of the study of the structural and optical properties reported here of the DPEA-MR-Zn organic semiconductor crystalline nanostructure thin film had shown various applications in many advanced technologies such as photovoltaic solar cells.

Beta-Adrenergic Receptor Expression in Muscle Cells

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, K.; Vaughn, J. R.

1999-01-01

beta-adrenergic receptor (bAR) agonists presumably exert their physiological action on skeletal muscle cells through the bAR. Since the signal generated by the bAR is cyclic AMP (cAMP), experiments were initiated in primary chicken muscle cell cultures to determine if artificial elevation of intracellular cAMP by treatment with forskolin would alter the population of bAR expressed on the surface of muscle cells. Chicken skeletal muscle cells after 7 days in culture were employed for the experiments because muscle cells have attained a steady state with respect to muscle protein metabolism at this stage. Cells were treated with 0-10 uM forskolin for a total of three days. At the end of the 1, 2, and 3 day treatment intervals, the concentration of cAMP and the bAR population were measured. Receptor population was measured in intact muscle cell cultures as the difference between total binding of [H-3]CGP-12177 and non-specific binding of [H-3]CGP-12177 in the presence of 1 uM propranolol. Intracellular cAMP concentration was measured by radioimmunoassay. The concentration of cAMP in forskolin-treated cells increased up to 10-fold in a dose dependent manner. Increasing concentrations of forskolin also led to an increase in (beta)AR population, with a maximum increase of approximately 50% at 10 uM. This increase in (beta)AR population was apparent after only 1 day of treatment, and the pattern of increase was maintained for all 3 days of the treatment period. Thus, increasing the intracellular concentration of cAMP leads to up-regulation of (beta)AR population. Clenbuterol and isoproterenol gave similar effects on bAR population. The effect of forskolin on the quantity and apparent synthesis rate of the heavy chain of myosin (mhc) were also investigated. A maximum increase of 50% in the quantity of mhc was observed at 0.2 UM forskolin, but higher concentrations of forskolin reduced the quantity of mhc back to control levels.

A new photometric model of the Galactic bar using red clump giants

NASA Astrophysics Data System (ADS)

Cao, Liang; Mao, Shude; Nataf, David; Rattenbury, Nicholas J.; Gould, Andrew

2013-09-01

We present a study of the luminosity density distribution of the Galactic bar using number counts of red clump giants from the Optical Gravitational Lensing Experiment (OGLE) III survey. The data were recently published by Nataf et al. for 9019 fields towards the bulge and have 2.94 × 106 RC stars over a viewing area of 90.25 deg^2. The data include the number counts, mean distance modulus (μ), dispersion in μ and full error matrix, from which we fit the data with several triaxial parametric models. We use the Markov Chain Monte Carlo method to explore the parameter space and find that the best-fitting model is the E3 model, with the distance to the GC 8.13 kpc, the ratio of semimajor and semiminor bar axis scalelengths in the Galactic plane x0, y0 and vertical bar scalelength z0 x0: y0: z0 ≈ 1.00: 0.43: 0.40 (close to being prolate). The scalelength of the stellar density profile along the bar's major axis is ˜0.67 kpc and has an angle of 29.4°, slightly larger than the value obtained from a similar study based on OGLE-II data. The number of estimated RC stars within the field of view is 2.78 × 106, which is systematically lower than the observed value. We subtract the smooth parametric model from the observed counts and find that the residuals are consistent with the presence of an X-shaped structure in the Galactic Centre, the excess to the estimated mass content is ˜5.8 per cent. We estimate that the total mass of the bar is ˜1.8 × 1010 M⊙. Our results can be used as a key ingredient to construct new density models of the Milky Way and will have implications on the predictions of the optical depth to gravitational microlensing and the patterns of hydrodynamical gas flow in the Milky Way.

Methodology of automated ionosphere front velocity estimation for ground-based augmentation of GNSS

NASA Astrophysics Data System (ADS)

Bang, Eugene; Lee, Jiyun

2013-11-01

ionospheric anomalies occurring during severe ionospheric storms can pose integrity threats to Global Navigation Satellite System (GNSS) Ground-Based Augmentation Systems (GBAS). Ionospheric anomaly threat models for each region of operation need to be developed to analyze the potential impact of these anomalies on GBAS users and develop mitigation strategies. Along with the magnitude of ionospheric gradients, the speed of the ionosphere "fronts" in which these gradients are embedded is an important parameter for simulation-based GBAS integrity analysis. This paper presents a methodology for automated ionosphere front velocity estimation which will be used to analyze a vast amount of ionospheric data, build ionospheric anomaly threat models for different regions, and monitor ionospheric anomalies continuously going forward. This procedure automatically selects stations that show a similar trend of ionospheric delays, computes the orientation of detected fronts using a three-station-based trigonometric method, and estimates speeds for the front using a two-station-based method. It also includes fine-tuning methods to improve the estimation to be robust against faulty measurements and modeling errors. It demonstrates the performance of the algorithm by comparing the results of automated speed estimation to those manually computed previously. All speed estimates from the automated algorithm fall within error bars of ± 30% of the manually computed speeds. In addition, this algorithm is used to populate the current threat space with newly generated threat points. A larger number of velocity estimates helps us to better understand the behavior of ionospheric gradients under geomagnetic storm conditions.

Customized oligonucleotide microchips that convert multiple genetic information to simple patterns, are portable and reusable

DOEpatents

Mirzabekov, Andrei; Guschin, Dmitry Y.; Chik, Valentine; Drobyshev, Aleksei; Fotin, Alexander; Yershov, Gennadiy; Lysov, Yuri

2002-01-01

This invention relates to using customized oligonucleotide microchips as biosensors for the detection and identification of nucleic acids specific for different genes, organisms and/or individuals in the environment, in food and in biological samples. The microchips are designed to convert multiple bits of genetic information into simpler patterns of signals that are interpreted as a unit. Because of an improved method of hybridizing oligonucleotides from samples to microchips, microchips are reusable and transportable. For field study, portable laser or bar code scanners are suitable.

Intellectual Dummies

NASA Technical Reports Server (NTRS)

2002-01-01

Goddard Space Flight Center and Triangle Research & Development Corporation collaborated to create "Smart Eyes," a charge coupled device camera that, for the first time, could read and measure bar codes without the use of lasers. The camera operated in conjunction with software and algorithms created by Goddard and Triangle R&D that could track bar code position and direction with speed and precision, as well as with software that could control robotic actions based on vision system input. This accomplishment was intended for robotic assembly of the International Space Station, helping NASA to increase production while using less manpower. After successfully completing the two- phase SBIR project with Goddard, Triangle R&D was awarded a separate contract from the U.S. Department of Transportation (DOT), which was interested in using the newly developed NASA camera technology to heighten automotive safety standards. In 1990, Triangle R&D and the DOT developed a mask made from a synthetic, plastic skin covering to measure facial lacerations resulting from automobile accidents. By pairing NASA's camera technology with Triangle R&D's and the DOT's newly developed mask, a system that could provide repeatable, computerized evaluations of laceration injury was born.

Extraction of carotenoids and chlorophyll from microalgae with supercritical carbon dioxide and ethanol as cosolvent.

PubMed

Macías-Sánchez, Maria Dolores; Mantell Serrano, Casimiro; Rodríguez Rodríguez, Miguel; Martínez de la Ossa, Enrique; Lubián, Luís M; Montero, Olimpio

2008-05-01

The extraction of carotenoids and chlorophylls using carbon dioxide modified with ethanol as a cosolvent is an alternative to solvent extraction because it provides a high-speed extraction process. In the study described here, carotenoid and chlorophyll extraction with supercritical CO(2 )+ ethanol was explored using freeze-dried powders of three microalgae (Nannochloropsis gaditana, Synechococcus sp. and Dunaliella salina) as the raw materials. The operation conditions were as follows: pressures of 200, 300, 400 and 500 bar, temperatures of 40, 50 and 60 degrees C. Analysis of the extracts was performed by measuring the absorbance and by using empirical correlations. The results demonstrate that it is necessary to work at a temperature of 50-60 degrees C and a pressure range of 300-500 bar, depending on the type of microalgae, in order to obtain the highest yield of pigments. The best carotenoid/chlorophyll ratios were obtained by using supercritical fluid extraction + cosolvent instead of using conventional extraction. The higher selectivity of the former process should facilitate the separation and purification of the two extracted pigments.

Development and application of stir bar sorptive extraction with polyurethane foams for the determination of testosterone and methenolone in urine matrices.

PubMed

Sequeiros, R C P; Neng, N R; Portugal, F C M; Pinto, M L; Pires, J; Nogueira, J M F

2011-04-01

This work describes the development, validation, and application of a novel methodology for the determination of testosterone and methenolone in urine matrices by stir bar sorptive extraction using polyurethane foams [SBSE(PU)] followed by liquid desorption and high-performance liquid chromatography with diode array detection. The methodology was optimized in terms of extraction time, agitation speed, pH, ionic strength and organic modifier, as well as back-extraction solvent and desorption time. Under optimized experimental conditions, convenient accuracy were achieved with average recoveries of 49.7 8.6% for testosterone and 54.2 ± 4.7% for methenolone. Additionally, the methodology showed good precision (<9%), excellent linear dynamic ranges (>0.9963) and convenient detection limits (0.2-0.3 μg/L). When comparing the efficiency obtained by SBSE(PU) and with the conventional polydimethylsiloxane phase [SBSE(PDMS)], yields up to four-fold higher are attained for the former, under the same experimental conditions. The application of the proposed methodology for the analysis of testosterone and methenolone in urine matrices showed negligible matrix effects and good analytical performance.

Incremental comprehension of pitch relationships in written music: Evidence from eye movements.

PubMed

Hadley, Lauren V; Sturt, Patrick; Eerola, Tuomas; Pickering, Martin J

2017-03-17

To investigate how proficient pianists comprehend pitch relationships in written music when they first encounter it we conducted two experiments in which proficient pianists' eyes were tracked while they read and played single-line melodies. In Experiment 1, participants played at their own speed; in Experiment 2 they played with an external metronome. The melodies were either congruent or anomalous, with the anomaly involving one bar being shifted in pitch to alter the implied harmonic structure (e.g., non-resolution of a dominant). In both experiments, anomaly led to rapid disruption in participants' eye-movements in terms of regressions from the target bar, indicating that pianists process written pitch relationships online. This is particularly striking because in musical sight-reading eye movement behaviour is constrained by the concurrent performance. Both experiments also showed that anomaly induced pupil dilation. Together these results indicate that proficient pianists rapidly integrate the music that they read into the prior context, and that anomalies in terms of pitch relationships lead to processing difficulty. These findings parallel those of text reading, suggesting that structural processing involves similar constraints across domains.

Increasing Navigation Speed at Endoluminal CT Colonography Reduces Colonic Visualization and Polyp Identification.

PubMed

Plumb, Andrew A; Phillips, Peter; Spence, Graeme; Mallett, Susan; Taylor, Stuart A; Halligan, Steve; Fanshawe, Thomas

2017-08-01

Purpose To investigate the effect of increasing navigation speed on the visual search and decision making during polyp identification for computed tomography (CT) colonography Materials and Methods Institutional review board permission was obtained to use deidentified CT colonography data for this prospective reader study. After obtaining informed consent from the readers, 12 CT colonography fly-through examinations that depicted eight polyps were presented at four different fixed navigation speeds to 23 radiologists. Speeds ranged from 1 cm/sec to 4.5 cm/sec. Gaze position was tracked by using an infrared eye tracker, and readers indicated that they saw a polyp by clicking a mouse. Patterns of searching and decision making by speed were investigated graphically and by multilevel modeling. Results Readers identified polyps correctly in 56 of 77 (72.7%) of viewings at the slowest speed but in only 137 of 225 (60.9%) of viewings at the fastest speed (P = .004). They also identified fewer false-positive features at faster speeds (42 of 115; 36.5%) of videos at slowest speed, 89 of 345 (25.8%) at fastest, P = .02). Gaze location was highly concentrated toward the central quarter of the screen area at faster speeds (mean gaze points at slowest speed vs fastest speed, 86% vs 97%, respectively). Conclusion Faster navigation speed at endoluminal CT colonography led to progressive restriction of visual search patterns. Greater speed also reduced both true-positive and false-positive colorectal polyp identification. © RSNA, 2017 Online supplemental material is available for this article.

Characterization of the actuator of EMIR configurable slit unit

NASA Astrophysics Data System (ADS)

Mato Martínez, A.; Núñez Cagigal, M.; Barreto Cabrera, M.; Garzón López, F.; Patrón, J.; Teuwen, M.

2016-07-01

EMIR1,2 (Espectrógrafo Multiobjeto Infra-Rojo) is a wide field multi-object spectrograph already installed in the Nasmyth focus of GTC (Gran Telescopio Canarias). It operates in the near-infrared (NIR), in the wavelength range from 0.9 μm to 2.5 μm and it will include several mechanism working in cryogenic conditions. A key component of EMIR is the CSU (Configurable Slit Unit), which is a robotic cryo-mechanism used to generate a multi-slit configuration and a long slit on EMIR focal plane when working in spectroscopic mode. The system has 110 sliding bars which can be configured at cryogenic working temperature to create up to 55 slits with a high position accuracy and repeatability. The movement of the bars is performed by an actuator which allows reaching a relatively high speed for the coarse movement and controllable steps up to 2 microns for the fine positioning. This subsystem has been designed and manufactured by the Dutch company Janssen Precision Engineering (JPE) and the Spanish company NTE-SENER. Afterwards, it was thoroughly verified at the IAC (Instituto de Astrofísica de Canarias) facilities. In this paper, the CSU will be briefly described. One of the more important parts of the CSU is the actuators, which move the bars by means of a stick-slip effect. A set of tests designed for characterizing and improving the robustness and performance of the actuators will be presented. Finally, an overview of the current CSU performance will be presented.

Direct Urca Processes Involving Proton 1 S 0 Superfluidity in Neutron Star Cooling

NASA Astrophysics Data System (ADS)

Xu, Yan; Yu, Zi; Zhang, Xiao-Jun; Fan, Cun-Bo; Liu, Guang-Zhou; Zhao, En-Guang; Huang, Xiu-Lin; Liu, Cheng-Zhi

2018-04-01

A detailed description of the baryon direct Urca processes A: n\\to p+e+{\\bar{ν }}e, B: Λ \\to p+e+{\\bar{ν }}e and C: {\\Xi }-\\to Λ +e+{\\bar{ν }}e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range (1.603–2.067) M⊙ ((1.515–1.840) M⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton 1 S 0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton 1 S 0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling. Supported by the National Natural Science Foundation of China under Grant Nos. 11447165, 11373047, 11404336 and U1731240, Youth Innovation Promotion Association, CAS under Grant No. 2016056, and the Development Project of Science and Technology of Jilin Province under Grant No. 20180520077JH

Experimental investigation of the cornering characteristics of 18 by 5.5, type 7, aircraft tires with different tread patterns

NASA Technical Reports Server (NTRS)

Dreher, R. C.; Tanner, J. A.

1974-01-01

The characteristics, which include the cornering-force and drag-force friction coefficients and self-alining torque, were obtained on dry, damp, and flooded runway surfaces over a range of yaw angles from 0 deg to 12 deg and at ground speeds from approximately 5 to 90 knots. The results indicate that a tread pattern with pinholes in the ribs reduces the tire cornering capability at high yaw angles on a damp surface but improves cornering on a dry surface. A tread pattern which has transverse grooves across the entire width of the tread improves the tire cornering performance slightly at high speeds on the flooded runway surface. The cornering capability of all the tires is degraded at high ground speeds by thin film lubrication and/or tire hydroplaning effects. Alterations to the conventional tread pattern provide only marginal improvements in the tire cornering capability which suggests that runway surface treatments may be a more effective way of improving aircraft ground performance during wet operations.

Fourier Theory Explanation for the Sampling Theorem Demonstrated by a Laboratory Experiment.

ERIC Educational Resources Information Center

Sharma, A.; And Others

1996-01-01

Describes a simple experiment that uses a CCD video camera, a display monitor, and a laser-printed bar pattern to illustrate signal sampling problems that produce aliasing or moiri fringes in images. Uses the Fourier transform to provide an appropriate and elegant means to explain the sampling theorem and the aliasing phenomenon in CCD-based…

Characteristics of digital micromirror projection for 3D shape measurement at extreme speed

NASA Astrophysics Data System (ADS)

Höfling, Roland; Aswendt, Petra; Leischnig, Frank; Förster, Matthias

2015-03-01

3D shape measurement is one of the growing industrial applications of the Texas Instruments DLP® micro-mirror device. This paper presents investigations on precision and repeatability of that spatial light modulators output when it is driven up to its high-speed limit. The study concerns the basic switching behavior of the individual micro-mirror at different frame rates ranging over three orders of magnitude. The 3D shape measuring methodologies are focused on phase encoded triangulation, i.e. the projection of sinusoidal patterns. The DLP chip is a bi-stable device providing an on/off pattern at each certain moment in time, i.e. it has a native binary output. Sinusoidal patterns are the result of either a temporal integration of multiple on/off patterns or a spatial integration within one on/off pattern. Both approaches are studied experimentally with respect to precision and stability of the pattern output. The STAR-07 industrial projection unit, based upon the 0.7" DLP Discovery™4100 chipset, has been used for this work and the pattern frame rates cover the range from 225 frames per second (fps) to 50,000 fps. The STAR-07 output is detected by a photodiode, amplified, and analyzed in a Yokogawa digital storage oscilloscope. All results prove the very high precision and repeatability of the STAR-07 pattern projection, up to the extreme speed of 50,000 fps.

Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS

NASA Astrophysics Data System (ADS)

Baines, Kevin H.; Momary, Thomas W.; Fletcher, Leigh N.; Showman, Adam P.; Roos-Serote, Maarten; Brown, Robert H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.

2009-12-01

A high-speed cyclonic vortex centered on the north pole of Saturn has been revealed by the visual-infrared mapping spectrometer (VIMS) onboard the Cassini-Huygens Orbiter, thus showing that the tropospheres of both poles of Saturn are occupied by cyclonic vortices with winds exceeding 135 m/s. High-spatial-resolution (~200 km per pixel) images acquired predominantly under night-time conditions during Saturn's polar winter - using a thermal wavelength of 5.1 μm to obtain time-lapsed imagery of discrete, deep-seated (>2.1-bar) cloud features viewed in silhouette against Saturn's internally generated thermal glow - show a classic cyclonic structure, with prograde winds exceeding 135 m/s at its maximum near 88.3° (planetocentric) latitude, and decreasing to <30 m/s at 89.7° near the vortex center and<20 m/s at 80.5°. High-speed winds, exceeding 125 m/s, were also measured for cloud features at depth near 76° (planetocentric) latitude within the polar hexagon consistent with the idea that the hexagon itself, which remains nearly stationary, is a westward (retrograde) propagating Rossby wave - as proposed by Allison (1990, Science 247, 1061-1063) - with a maximum wave speed near 2-bars pressure of ~125 m/s. Winds are ~25 m/s stronger than observed by Voyager, suggesting temporal variability. Images acquired of one side of the hexagon in dawn conditions as the polar winter wanes shows the hexagon is still visible in reflected sunlight nearly 28 years since its discovery, that a similar 3-lane structure is observed in reflected and thermal light, and that the cloudtops may be typically lower in the hexagon than in nearby discrete cloud features outside of it. Clouds are well-correlated in visible and 5.1 μm images, indicating little windshear above the ~2-bar level. The polar cyclone is similar in size and shape to its counterpart at the south pole; a primary difference is the presence of a small (<600 km in diameter) nearly pole-centered cloud, perhaps indicative of localized upwelling. Many dozens of discrete, circular cloud features dot the polar region, with typical diameters of 300-700 km. Equatorward of 87.8°N, their compact nature in the high-wind polar environment suggests that vertical shear in horizontal winds may be modest on 1000 km scales. These circular clouds may be anticyclonic vortices produced by baroclinic instabilities, barotropic instabilities, moist convection or other processes. The existence of cyclones at both poles of Saturn indicates that cyclonic circulation may be an important dynamical style in planets with significant atmospheres.

Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS

USGS Publications Warehouse

Baines, K.H.; Momary, T.W.; Fletcher, L.N.; Showman, A.P.; Roos-Serote, M.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

2009-01-01

A high-speed cyclonic vortex centered on the north pole of Saturn has been revealed by the visual-infrared mapping spectrometer (VIMS) onboard the Cassini-Huygens Orbiter, thus showing that the tropospheres of both poles of Saturn are occupied by cyclonic vortices with winds exceeding 135 m/s. High-spatial-resolution (~200 km per pixel) images acquired predominantly under night-time conditions during Saturn's polar winter-using a thermal wavelength of 5.1 ??m to obtain time-lapsed imagery of discrete, deep-seated (>2.1-bar) cloud features viewed in silhouette against Saturn's internally generated thermal glow-show a classic cyclonic structure, with prograde winds exceeding 135 m/s at its maximum near 88.3?? (planetocentric) latitude, and decreasing to <30 m/s at 89.7?? near the vortex center and<20 m/s at 80.5??. High-speed winds, exceeding 125 m/s, were also measured for cloud features at depth near 76?? (planetocentric) latitude within the polar hexagon consistent with the idea that the hexagon itself, which remains nearly stationary, is a westward (retrograde) propagating Rossby wave - as proposed by Allison (1990, Science 247, 1061-1063) - with a maximum wave speed near 2-bars pressure of ~125 m/s. Winds are ~25 m/s stronger than observed by Voyager, suggesting temporal variability. Images acquired of one side of the hexagon in dawn conditions as the polar winter wanes shows the hexagon is still visible in reflected sunlight nearly 28 years since its discovery, that a similar 3-lane structure is observed in reflected and thermal light, and that the cloudtops may be typically lower in the hexagon than in nearby discrete cloud features outside of it. Clouds are well-correlated in visible and 5.1 ??m images, indicating little windshear above the ~2-bar level. The polar cyclone is similar in size and shape to its counterpart at the south pole; a primary difference is the presence of a small (<600 km in diameter) nearly pole-centered cloud, perhaps indicative of localized upwelling. Many dozens of discrete, circular cloud features dot the polar region, with typical diameters of 300-700 km. Equatorward of 87.8??N, their compact nature in the high-wind polar environment suggests that vertical shear in horizontal winds may be modest on 1000 km scales. These circular clouds may be anticyclonic vortices produced by baroclinic instabilities, barotropic instabilities, moist convection or other processes. The existence of cyclones at both poles of Saturn indicates that cyclonic circulation may be an important dynamical style in planets with significant atmospheres. ?? 2009 Elsevier Ltd. All rights reserved.

Gray matter volume and dual-task gait performance in mild cognitive impairment.

PubMed

Doi, Takehiko; Blumen, Helena M; Verghese, Joe; Shimada, Hiroyuki; Makizako, Hyuma; Tsutsumimoto, Kota; Hotta, Ryo; Nakakubo, Sho; Suzuki, Takao

2017-06-01

Dual-task gait performance is impaired in older adults with mild cognitive impairment, but the brain substrates associated with dual-task gait performance are not well-established. The relationship between gray matter and gait speed under single-task and dual-task conditions (walking while counting backward) was examined in 560 seniors with mild cognitive impairment (non-amnestic mild cognitive impairment: n = 270; mean age = 72.4 yrs., 63.6 % women; amnestic mild cognitive impairment: n = 290; mean age = 73.4 yrs., 45.4 % women). Multivariate covariance-based analyses of magnetic resonance imaging data, adjusted for potential confounders including single-task gait speed, were performed to identify gray matter patterns associated with dual-task gait speed. There were no differences in gait speed or cognitive performance during dual-task gait between individuals with non-amnestic mild cognitive impairment and amnestic mild cognitive impairment. Overall, increased dual-task gait speed was associated with a gray matter pattern of increased volume in medial frontal gyrus, superior frontal gyrus, anterior cingulate, cingulate, precuneus, fusiform gyrus, middle occipital gyrus, inferior temporal gyrus and middle temporal gyrus. The relationship between dual-task gait speed and brain substrates also differed by mild cognitive impairment subtype. Our study revealed a pattern of gray matter regions associated with dual-task performance. Although dual-task gait performance was similar in amnestic and non-amnestic mild cognitive impairment, the gray matter patterns associated with dual-task gait performance differed by mild cognitive impairment subtype. These findings suggest that the brain substrates supporting dual-task gait performance in amnestic and non-amnestic subtypes are different, and consequently may respond differently to interventions, or require different interventions.

Energy budgets and a climate space diagram for the turtle, Chrysemys scripta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foley, R. E.

1976-01-01

Heat energy budgets were computed and a steady state climate space was generated for a 1000 g red-eared turtle (Chrysemys scripta). Evaporative water loss (EWL) was measured from C. scripta at three wind speeds (10-400 cm sec/sup -1/) and at four air temperatures (5 to 35/sup 0/C) in a wind tunnel. EWL increased as air temperature and wind speed increased. Smaller turtles dehydrated at a faster rate than large turtles. Heat transfer by convection was measured from aluminum castings of C. scripta at three temperature differences between casting and air (..delta..T 15/sup 0/, 10/sup 0/ and 5/sup 0/C) for threemore » windspeeds (10 to 400 cm sec/sup -1/). Convective heat transfer coefficients increased as wind speed and ..delta..T increased. Wind speed has a large effect on the shape of the climate space. At high wind speeds, heat loss by evaporation and convection are greatly increased. In still air (10 cm sec/sup -1/), a turtle cannot remain exposed to full sunlight when air temperatures exceed 19/sup 0/C. When wind speed increases to 400 cm sec/sup -1/, the turtle can bask for long periods of time at temperatures as high as 32/sup 0/C. Basking patterns of C. scripta probably shift from a unimodal pattern in the spring to a bimodal pattern in summer and return to a unimodal pattern in fall. Terrestrial activity may be extensive in the spring and fall but is limited during the hot summer months to periods of rainfall. Nesting activities cannot occur around solar noon because increased metabolic heat loading and high solar radiation intensity could cause death.« less

Gray matter volume and dual-task gait performance in mild cognitive impairment

PubMed Central

Blumen, Helena M.; Verghese, Joe; Shimada, Hiroyuki; Makizako, Hyuma; Tsutsumimoto, Kota; Hotta, Ryo; Nakakubo, Sho; Suzuki, Takao

2017-01-01

Dual-task gait performance is impaired in older adults with mild cognitive impairment, but the brain substrates associated with dual-task gait performance are not well-established. The relationship between gray matter and gait speed under single-task and dual-task conditions (walking while counting backward) was examined in 560 seniors with mild cognitive impairment (non-amnestic mild cognitive impairment: n = 270; mean age = 72.4 yrs., 63.6 % women; amnestic mild cognitive impairment: n = 290; mean age = 73.4 yrs., 45.4 % women). Multivariate covariance-based analyses of magnetic resonance imaging data, adjusted for potential confounders including single-task gait speed, were performed to identify gray matter patterns associated with dual-task gait speed. There were no differences in gait speed or cognitive performance during dual-task gait between individuals with non-amnestic mild cognitive impairment and amnestic mild cognitive impairment. Overall, increased dual-task gait speed was associated with a gray matter pattern of increased volume in medial frontal gyrus, superior frontal gyrus, anterior cingulate, cingulate, precuneus, fusiform gyrus, middle occipital gyrus, inferior temporal gyrus and middle temporal gyrus. The relationship between dual-task gait speed and brain substrates also differed by mild cognitive impairment subtype. Our study revealed a pattern of gray matter regions associated with dual-task performance. Although dual-task gait performance was similar in amnestic and non-amnestic mild cognitive impairment, the gray matter patterns associated with dual-task gait performance differed by mild cognitive impairment subtype. These findings suggest that the brain substrates supporting dual-task gait performance in amnestic and non-amnestic subtypes are different, and consequently may respond differently to interventions, or require different interventions. PMID:27392792

High-speed three-dimensional shape measurement for dynamic scenes using bi-frequency tripolar pulse-width-modulation fringe projection

NASA Astrophysics Data System (ADS)

Zuo, Chao; Chen, Qian; Gu, Guohua; Feng, Shijie; Feng, Fangxiaoyu; Li, Rubin; Shen, Guochen

2013-08-01

This paper introduces a high-speed three-dimensional (3-D) shape measurement technique for dynamic scenes by using bi-frequency tripolar pulse-width-modulation (TPWM) fringe projection. Two wrapped phase maps with different wavelengths can be obtained simultaneously by our bi-frequency phase-shifting algorithm. Then the two phase maps are unwrapped using a simple look-up-table based number-theoretical approach. To guarantee the robustness of phase unwrapping as well as the high sinusoidality of projected patterns, TPWM technique is employed to generate ideal fringe patterns with slight defocus. We detailed our technique, including its principle, pattern design, and system setup. Several experiments on dynamic scenes were performed, verifying that our method can achieve a speed of 1250 frames per second for fast, dense, and accurate 3-D measurements.

Use of heavier drinking contexts among heterosexuals, homosexuals and bisexuals: results from a National Household Probability Survey.

PubMed

Trocki, Karen F; Drabble, Laurie; Midanik, Lorraine

2005-01-01

Extensive use of specific social contexts (bars and parties, for instance) by homosexuals and bisexuals is thought to be a factor in the higher rates of drinking among these groups. However, much of the empirical evidence behind these assumptions has been based on studies with methodological or sampling shortcomings. This article examines the epidemiological patterns of alcohol contexts in relation to sexual identity, using a large, national, probability population survey. We used the 2000 National Alcohol Survey for these analyses. The prevalence of spending leisure time in each of two social contexts (bars and parties) that are associated with heavier drinking is examined by sexual orientation (heterosexual, homosexual, bisexual and self-identified heterosexuals with same sex partners). In addition, we compare levels of drinking within these contexts by sexual orientation within these groups. Exclusively heterosexual women spent less time in these two contexts relative to all other groups of women. Gay men spent considerably more time in bars compared with the other groups of men. Heterosexual women who reported same sex partners drink more at bars, and bisexual women drink more alcohol at both bars and parties than exclusively heterosexual women. For men, there were no significant differences for average consumption in any of these contexts. Entry of background and demographic variables into logistic regression analyses did little to modify these associations. There is empirical evidence that some groups of homosexual and bisexual women and men spend more time than heterosexual individuals in heavier drinking contexts. The frequency of being in these two social contexts does not appear to be associated with heavier drinking within these contexts for men, but it may be related to heavier drinking in those places among some groups of women.

Evidence for the Involvement of p38 MAPK Activation in Barnacle Larval Settlement

PubMed Central

He, Li-Sheng; Xu, Ying; Matsumura, Kiyotaka; Zhang, Yu; Zhang, Gen; Qi, Shu-Hua; Qian, Pei-Yuan

2012-01-01

The barnacle Balanus ( = Amphibalanus) amphitrite is a major marine fouling animal. Understanding the molecular mechanism of larval settlement in this species is critical for anti-fouling research. In this study, we cloned one isoform of p38 MAPK (Bar-p38 MAPK) from this species, which shares the significant characteristic of containing a TGY motif with other species such as yeast, Drosophila and humans. The activation of p38 MAPK was detected by an antibody that recognizes the conserved dual phosphorylation sites of TGY. The results showed that phospho-p38 MAPK (pp38 MAPK) was more highly expressed at the cyprid stage, particularly in aged cyprids, in comparison to other stages, including the nauplius and juvenile stages. Immunostaining showed that Bar-p38 MAPK and pp38 MAPK were mainly located at the cyprid antennules, and especially the third and fourth segments, which are responsible for substratum exploration during settlement. The expression and localization patterns of Bar-p38 MAPK suggest its involvement in larval settlement. This postulation was also supported by the larval settlement bioassay with the p38 MAPK inhibitor SB203580. Behavioral analysis by live imaging revealed that the larvae were still capable of exploring the surface of the substratum after SB203580 treatment. This shows that the effect of p38 MAPK on larval settlement might be by regulating the secretion of permanent proteinaceous substances. Furthermore, the level of pp38 MAPK dramatically decreased after full settlement, suggesting that Bar-p38 MAPK maybe plays a role in larval settlement rather than metamorphosis. Finally, we found that Bar-p38 MAPK was highly activated when larvae confronted extracts of adult barnacle containing settlement cues, whereas larvae pre-treated with SB203580 failed to respond to the crude adult extracts. PMID:23115639

Effects of a healthier snack on snacking habits and glycated Hb (HbA1c): a 6-week intervention study.

PubMed

Yan, Mary R; Parsons, Andrew; Whalley, Gillian A; Rush, Elaine C

2016-12-01

Dietary behaviour modification may change eating habits and reduce the impact of poor nutrition. This study aimed to evaluate the effects of daily consumption of a healthier snack bar on snacking habits and glycated Hb (HbA1c) within a 6-week intervention. In all, twenty-eight participants were randomly allocated to two groups to either consume the bars as the main snack for 6 weeks (n 14) or receipt of the bars was delayed for 6 weeks (n 14) following a stepped-wedge design. All participants had HbA1c concentrations measured at weeks -1, 0, 4, 6, 10 and 12. A short dietary habits questionnaire was self-completed at weeks 0, 6 and 12. Participants consumed the bars they received instead of other snacks, and found that the healthier snack bar was acceptable as part of their daily dietary pattern. Over the 12 weeks, there was a significant reduction in intake of biscuits, cakes and pies (approximately 2 servings/week, P<0·05) in both groups. Fruit juice intake was reduced (approximately 1 serving/week, P=0·029) in the first group. In all, twenty participants (71·4 %) experienced a decrease (n 15) or no change (n 5) in HbA1c (range 0-4 mmol/mol), whereas eight participants experienced an increase in HbA1c (range 0·5-2·5 mmol/mol). There was high compliance with the healthier snack intervention and a trend towards a favourable effect on glucose homoeostasis. Habitual snacking behaviour has the potential to be improved through changes in the food supply, and in the longer term may reduce the impact of poor nutrition on public health.

Testing the carotenoid trade-off hypothesis in the polychromatic Midas cichlid, Amphilophus citrinellus.

PubMed

Lin, Susan M; Nieves-Puigdoller, Katherine; Brown, Alexandria C; McGraw, Kevin J; Clotfelter, Ethan D

2010-01-01

Many animals use carotenoid pigments derived from their diet for coloration and immunity. The carotenoid trade-off hypothesis predicts that, under conditions of carotenoid scarcity, individuals may be forced to allocate limited carotenoids to either coloration or immunity. In polychromatic species, the pattern of allocation may differ among individuals. We tested the carotenoid trade-off hypothesis in the Midas cichlid, Amphilophus citrinellus, a species with two ontogenetic color morphs, barred and gold, the latter of which is the result of carotenoid expression. We performed a diet-supplementation experiment in which cichlids of both color morphs were assigned to one of two diet treatments that differed only in carotenoid content (beta-carotene, lutein, and zeaxanthin). We measured integument color using spectrometry, quantified carotenoid concentrations in tissue and plasma, and assessed innate immunity using lysozyme activity and alternative complement pathway assays. In both color morphs, dietary carotenoid supplementation elevated plasma carotenoid circulation but failed to affect skin coloration. Consistent with observable differences in integument coloration, we found that gold fish sequestered more carotenoids in skin tissue than barred fish, but barred fish had higher concentrations of carotenoids in plasma than gold fish. Neither measure of innate immunity differed between gold and barred fish, or as a function of dietary carotenoid supplementation. Lysozyme activity, but not complement activity, was strongly affected by body condition. Our data show that a diet low in carotenoids is sufficient to maintain both coloration and innate immunity in Midas cichlids. Our data also suggest that the developmental transition from the barred to gold morph is not accompanied by a decrease in innate immunity in this species.

Fabrication of cross-shaped Cu-nanowire resistive memory devices using a rapid, scalable, and designable inorganic-nanowire-digital-alignment technique (Conference Presentation)

NASA Astrophysics Data System (ADS)

Xu, Wentao; Lee, Yeongjun; Min, Sung-Yong; Park, Cheolmin; Lee, Tae-Woo

2016-09-01

Resistive random-access memory (RRAM) is a candidate next generation nonvolatile memory due to its high access speed, high density and ease of fabrication. Especially, cross-point-access allows cross-bar arrays that lead to high-density cells in a two-dimensional planar structure. Use of such designs could be compatible with the aggressive scaling down of memory devices, but existing methods such as optical or e-beam lithographic approaches are too complicated. One-dimensional inorganic nanowires (i-NWs) are regarded as ideal components of nanoelectronics to circumvent the limitations of conventional lithographic approaches. However, post-growth alignment of these i-NWs precisely on a large area with individual control is still a difficult challenge. Here, we report a simple, inexpensive, and rapid method to fabricate two-dimensional arrays of perpendicularly-aligned, individually-conductive Cu-NWs with a nanometer-scale CuxO layer sandwiched at each cross point, by using an inorganic-nanowire-digital-alignment technique (INDAT) and a one-step reduction process. In this approach, the oxide layer is self-formed and patterned, so conventional deposition and lithography are not necessary. INDAT eliminates the difficulties of alignment and scalable fabrication that are encountered when using currently-available techniques that use inorganic nanowires. This simple process facilitates fabrication of cross-point nonvolatile memristor arrays. Fabricated arrays had reproducible resistive switching behavior, high on/off current ratio (Ion/Ioff) 10 6 and extensive cycling endurance. This is the first report of memristors with the resistive switching oxide layer self-formed, self-patterned and self-positioned; we envision that the new features of the technique will provide great opportunities for future nano-electronic circuits.

Similarities and differences among half-marathon runners according to their performance level

PubMed Central

Morante, Juan Carlos; Gómez-Molina, Josué; García-López, Juan

2018-01-01

This study aimed to identify the similarities and differences among half-marathon runners in relation to their performance level. Forty-eight male runners were classified into 4 groups according to their performance level in a half-marathon (min): Group 1 (n = 11, < 70 min), Group 2 (n = 13, < 80 min), Group 3 (n = 13, < 90 min), Group 4 (n = 11, < 105 min). In two separate sessions, training-related, anthropometric, physiological, foot strike pattern and spatio-temporal variables were recorded. Significant differences (p<0.05) between groups (ES = 0.55–3.16) and correlations with performance were obtained (r = 0.34–0.92) in training-related (experience and running distance per week), anthropometric (mass, body mass index and sum of 6 skinfolds), physiological (VO2max, RCT and running economy), foot strike pattern and spatio-temporal variables (contact time, step rate and length). At standardized submaximal speeds (11, 13 and 15 km·h-1), no significant differences between groups were observed in step rate and length, neither in contact time when foot strike pattern was taken into account. In conclusion, apart from training-related, anthropometric and physiological variables, foot strike pattern and step length were the only biomechanical variables sensitive to half-marathon performance, which are essential to achieve high running speeds. However, when foot strike pattern and running speeds were controlled (submaximal test), the spatio-temporal variables were similar. This indicates that foot strike pattern and running speed are responsible for spatio-temporal differences among runners of different performance level. PMID:29364940

Protein functional features are reflected in the patterns of mRNA translation speed.

PubMed

López, Daniel; Pazos, Florencio

2015-07-09

The degeneracy of the genetic code makes it possible for the same amino acid string to be coded by different messenger RNA (mRNA) sequences. These "synonymous mRNAs" may differ largely in a number of aspects related to their overall translational efficiency, such as secondary structure content and availability of the encoded transfer RNAs (tRNAs). Consequently, they may render different yields of the translated polypeptides. These mRNA features related to translation efficiency are also playing a role locally, resulting in a non-uniform translation speed along the mRNA, which has been previously related to some protein structural features and also used to explain some dramatic effects of "silent" single-nucleotide-polymorphisms (SNPs). In this work we perform the first large scale analysis of the relationship between three experimental proxies of mRNA local translation efficiency and the local features of the corresponding encoded proteins. We found that a number of protein functional and structural features are reflected in the patterns of ribosome occupancy, secondary structure and tRNA availability along the mRNA. One or more of these proxies of translation speed have distinctive patterns around the mRNA regions coding for certain protein local features. In some cases the three patterns follow a similar trend. We also show specific examples where these patterns of translation speed point to the protein's important structural and functional features. This support the idea that the genome not only codes the protein functional features as sequences of amino acids, but also as subtle patterns of mRNA properties which, probably through local effects on the translation speed, have some consequence on the final polypeptide. These results open the possibility of predicting a protein's functional regions based on a single genomic sequence, and have implications for heterologous protein expression and fine-tuning protein function.

FastSim: A Fast Simulation for the SuperB Detector

NASA Astrophysics Data System (ADS)

Andreassen, R.; Arnaud, N.; Brown, D. N.; Burmistrov, L.; Carlson, J.; Cheng, C.-h.; Di Simone, A.; Gaponenko, I.; Manoni, E.; Perez, A.; Rama, M.; Roberts, D.; Rotondo, M.; Simi, G.; Sokoloff, M.; Suzuki, A.; Walsh, J.

2011-12-01

We have developed a parameterized (fast) simulation for detector optimization and physics reach studies of the proposed SuperB Flavor Factory in Italy. Detector components are modeled as thin sections of planes, cylinders, disks or cones. Particle-material interactions are modeled using simplified cross-sections and formulas. Active detectors are modeled using parameterized response functions. Geometry and response parameters are configured using xml files with a custom-designed schema. Reconstruction algorithms adapted from BaBar are used to build tracks and clusters. Multiple sources of background signals can be merged with primary signals. Pattern recognition errors are modeled statistically by randomly misassigning nearby tracking hits. Standard BaBar analysis tuples are used as an event output. Hadronic B meson pair events can be simulated at roughly 10Hz.

Melodic cues for metre.

PubMed

Vos, P G; van Dijk, A; Schomaker, L

1994-01-01

A method of time-series analysis and a time-beating experiment were used to test the structural and perceptual validity of notated metre. Autocorrelation applied to the flow of melodic intervals between notes from thirty fragments of compositions for solo instruments by J S Bach strongly supported the validity of bar length specifications. Time-beating data, obtained with four stimuli from the same set, played in an expressionless mode, and presented under categorically distinct tempos to different subgroups of musically trained subjects, were rather inconsistent with respect to tapped bar lengths. However, taps were most frequently given to the events in the stimuli that corresponded with the first beats according to the score notations. No significant effects of tempo on tapping patterns were observed. The findings are discussed in comparison with other examinations of metre inference from musical compositions.

Numerical simulation of active track tensioning system for autonomous hybrid vehicle

NASA Astrophysics Data System (ADS)

Mȩżyk, Arkadiusz; Czapla, Tomasz; Klein, Wojciech; Mura, Gabriel

2017-05-01

One of the most important components of a high speed tracked vehicle is an efficient suspension system. The vehicle should be able to operate both in rough terrain for performance of engineering tasks as well as on the road with high speed. This is especially important for an autonomous platform that operates either with or without human supervision, so that the vibration level can rise compared to a manned vehicle. In this case critical electronic and electric parts must be protected to ensure the reliability of the vehicle. The paper presents a dynamic parameters determination methodology of suspension system for an autonomous high speed tracked platform with total weight of about 5 tonnes and hybrid propulsion system. Common among tracked vehicles suspension solutions and cost-efficient, the torsion-bar system was chosen. One of the most important issues was determining optimal track tensioning - in this case an active hydraulic system was applied. The selection of system parameters was performed with using numerical model based on multi-body dynamic approach. The results of numerical analysis were used to define parameters of active tensioning control system setup. LMS Virtual.Lab Motion was used for multi-body dynamics numerical calculation and Matlab/SIMULINK for control system simulation.

Three-dimensional direct cell patterning in collagen hydrogels with near-infrared femtosecond laser

PubMed Central

Hribar, Kolin C.; Meggs, Kyle; Liu, Justin; Zhu, Wei; Qu, Xin; Chen, Shaochen

2015-01-01

We report a methodology for three-dimensional (3D) cell patterning in a hydrogel in situ. Gold nanorods within a cell-encapsulating collagen hydrogel absorb a focused near-infrared femtosecond laser beam, locally denaturing the collagen and forming channels, into which cells migrate, proliferate, and align in 3D. Importantly, pattern resolution is tunable based on writing speed and laser power, and high cell viability (>90%) is achieved using higher writing speeds and lower laser intensities. Overall, this patterning technique presents a flexible direct-write method that is applicable in tissue engineering systems where 3D alignment is critical (such as vascular, neural, cardiac, and muscle tissue). PMID:26603915

Context-Sensitive Grammar Transform: Compression and Pattern Matching

NASA Astrophysics Data System (ADS)

Maruyama, Shirou; Tanaka, Youhei; Sakamoto, Hiroshi; Takeda, Masayuki

A framework of context-sensitive grammar transform for speeding-up compressed pattern matching (CPM) is proposed. A greedy compression algorithm with the transform model is presented as well as a Knuth-Morris-Pratt (KMP)-type compressed pattern matching algorithm. The compression ratio is a match for gzip and Re-Pair, and the search speed of our CPM algorithm is almost twice faster than the KMP-type CPM algorithm on Byte-Pair-Encoding by Shibata et al.[18], and in the case of short patterns, faster than the Boyer-Moore-Horspool algorithm with the stopper encoding by Rautio et al.[14], which is regarded as one of the best combinations that allows a practically fast search.

Interannual (1999-2005) morphodynamic evolution of macro-tidal salt marshes in Mont-Saint-Michel Bay (France)

NASA Astrophysics Data System (ADS)

Détriché, Sébastien; Susperregui, Anne-Sophie; Feunteun, Eric; Lefeuvre, Jean-Claude; Jigorel, Alain

2011-04-01

This paper provides a detailed study on the sedimentation patterns and the recent morphodynamic evolution affecting the macro-tidal salt marshes located west of the Mont-Saint-Michel (France). Twenty-two stations along three transects on the marshes were seasonally monitored for marsh surface level variations from 1999 to 2005, using a sediment erosion bar. The corresponding erosion/accretion rates were obtained together with data on topography, vegetation cover, and grain size of surface sediment. To examine the mechanisms contributing to the salt marsh sedimentation, the data and their evolution were treated with respect to tides, relative mean regional sea level, and wind speed/frequency variations. From 1999 to 2005, the marsh was globally accreting (from 3.45 to 38.11 mm yr -1 in the low marsh, up to 4.91 mm yr -1 in the middle marsh, and up to 1.35 mm yr -1 in the high marsh), while the study was conducted during a window of decreasing trend in mean regional sea level (-2.45 mm yr -1 according to regional-averaged time series). These sedimentation rates are one of the highest recorded worldwide; however, the sedimentation was not found to be continuous over the period in question. This pattern is illustrated by the strong extension of the marshes from 1999 to 2002, and the relative stability observed from 2003 to 2005. The imported and reworked sediments are trapped and fixed by the dense vegetation ( Puccinellia maritima, Halimione portulacoides), inducing the general seaward extension of the marshes. The processes governing sediment budget (accretion/erosion) show annual, seasonal, and spatial variability on the marsh. Spatial variations display contrasted patterns of erosion/sedimentation between the low, middle, and high marsh, and between the different transects. These patterns are a result of distance from sediment sources, strong heterogeneity in vegetation cover (human induced or not), and contrasting topographic and micro-topographic characteristics. The higher accretion rates are observed in distal settings in the low marsh, and strongly decrease toward the middle and high marsh. This evolution results from a decrease in accommodation space/water column thickness, and frequency of inundation coupled with an increase in station elevation, but also from the cumulated effects of vegetation cover and micro-topography. The vegetation cover of the low and middle marsh enhance the settling and fixing of fine sediments imported through tides or dispersed by flood and ebb currents. The seasonal evolution of the marshes is marked by contrasting effects of water storage in the sediment. The overall seasonal sediment budget is controlled by the variation of the frequency of inundation relative to tidal range and marshes topography. Autumns are influenced by the tide (equinoxes), relative mean regional sea level, and variations in wind speed/frequency. Winter wind speed and frequency in relation with tidal variations appear to be the main parameters regulating winter marsh evolution. Summers are predominantly under the influence of local variations in water storage (desiccation) while external parameters generally display a low influence. Although it is not governed by any one parameter, springtime sediment budget seems to result from strong interaction between the above-cited parameters, despite the significant frequency of inundation (equinoxes).

Final-Approach Spacing Aids (FASA) evaluation for terminal-area, time-based air traffic control

NASA Technical Reports Server (NTRS)

Credeur, Leonard; Capron, William R.; Lohr, Gary W.; Crawford, Daniel J.; Tang, Dershuen A.; Rodgers, William G., Jr.

1993-01-01

A jointly funded (NASA/FAA) real-time simulation study was conducted at NASA Langley Research Center to gather comparative performance data among three candidate final-approach spacing aid (FASA) display formats. Several objective measures of controller performance and their display eye-scan behavior as well as subjective workload and rating questionnaires were used. For each of two representative pattern-speed procedures (a 170-knot procedure and a 210-knot procedure with speed control aiding), data were gathered, via twelve FAA controllers, using four final-controller display format conditions (manual/ARTS 3, graphic marker, DICE countdown, and centerline slot marker). Measured runway separations were more precise with both the graphic marker and DICE countdown formats than with the centerline slot marker and both (graphic and DICE) improved precision relative to the manual/ARTS 3 format. For three separate rating criteria, the subject controllers ranked the FASA formats in the same order: graphic marker, DICE countdown, and centerline slot marker. The increased precision measured with the 210-knot pattern-speed procedure may indicate the potential for the application of speed-control aiding where higher pattern speeds are practical after the base-to-final turn. Also presented are key FASA issues, a rationale for the formats selected for testing, and their description.

The machined surface of magnesium AZ31 after rotary turning at air cooling condition

NASA Astrophysics Data System (ADS)

Akhyar, G.; Purnomo, B.; Hamni, A.; Harun, S.; Burhanuddin, Y.

2018-04-01

Magnesium is a lightweight metal that is widely used as an alternative to iron and steel. Magnesium has been applied in the automotive industry to reduce the weight of a component, but the machining process has the disadvantage that magnesium is highly flammable because it has a low flash point. High temperature can cause the cutting tool wear and contributes to the quality of the surface roughness. The purpose of this study is to obtain the value of surface roughness and implement methods of rotary cutting tool and air cooling output vortex tube cooler to minimize the surface roughness values. Machining parameters that is turning using rotary cutting tool at speed the workpiece of (Vw) 50, 120, 160 m/min, cutting speed of rotary tool of (Vt) 25, 50, 75 m/min, feed rate of (f) 0.1, 0.15, 0.2 mm/rev, and depth of cut of 0.3 mm. Type of tool used is a carbide tool diameter of 16 mm and air cooling pressure of 6 bar. The results show the average value of the lowest surface roughness on the speed the workpiece of 80 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. While the average value of the highest surface roughness on the speed the workpiece of 160 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. The influence of machining parameters concluded the higher the speed of the workpiece the surface roughness value higher. Otherwise the higher cutting speed of rotary tool then the lower the surface roughness value. The observation on the surface of the rotary tool, it was found that no uniform tool wear which causes non-uniform surface roughness. The use of rotary cutting tool contributing to lower surface roughness values generated.

Forces Generated by Vastus Lateralis and Vastus Medialis Decrease with Increasing Stair Descent Speed.

PubMed

Caruthers, Elena J; Oxendale, Kassandra K; Lewis, Jacqueline M; Chaudhari, Ajit M W; Schmitt, Laura C; Best, Thomas M; Siston, Robert A

2018-04-01

Stair descent (SD) is a common, difficult task for populations who are elderly or have orthopaedic pathologies. Joint torques of young, healthy populations during SD increase at the hip and ankle with increasing speed but not at the knee, contrasting torque patterns during gait. To better understand the sources of the knee torque pattern, we used dynamic simulations to estimate knee muscle forces and how they modulate center of mass (COM) acceleration across SD speeds (slow, self-selected, and fast) in young, healthy adults. The vastus lateralis and vastus medialis forces decreased from slow to self-selected speeds as the individual lowered to the next step. Since the vasti are primary contributors to vertical support during SD, they produced lower forces at faster speeds due to the lower need for vertical COM support observed at faster speeds. In contrast, the semimembranosus and rectus femoris forces increased across successive speeds, allowing the semimembranosus to increase acceleration downward and forward and the rectus femoris to provide more vertical support and resistance to forward progression as SD speed increased. These results demonstrate the utility of dynamic simulations to extend beyond traditional inverse dynamics analyses to gain further insight into muscle mechanisms during tasks like SD.

On the unsteady gravity-capillary wave pattern found behind a slow moving localized pressure distribution

NASA Astrophysics Data System (ADS)

Masnadi, N.; Duncan, J. H.

2013-11-01

The non-linear response of a water surface to a slow-moving pressure distribution is studied experimentally using a vertically oriented carriage-mounted air-jet tube that is set to translate over the water surface in a long tank. The free surface deformation pattern is measured with a full-field refraction-based method that utilizes a vertically oriented digital movie camera (under the tank) and a random dot pattern (above the water surface). At towing speeds just below the minimum phase speed of gravity-capillary waves (cmin ~ 23 cm/s), an unsteady V-shaped pattern is formed behind the pressure source. Localized depressions are generated near the source and propagate in pairs along the two arms of the V-shaped pattern. These depressions are eventually shed from the tips of the pattern at a frequency of about 1 Hz. It is found that the shape and phase speeds of the first depressions shed in each run are quantitatively similar to the freely-propagating gravity-capillary lumps from potential flow calculations. In the experiments, the amplitudes of the depressions decrease by approximately 60 percent while travelling 12 wavelengths. The depressions shed later in each run behave in a less consistent manner, probably due to their interaction with neighboring depressions.

Stellar streams and the galaxies they reside in

NASA Astrophysics Data System (ADS)

Pearson, Sarah

2018-01-01

As galaxies collide, as smaller galaxies are disrupted by larger galaxies, or as clusters of stars orbit a galaxy, a gravitational tidal interaction unfolds and the systems tear apart into distinct morphological and kinematic structures. In my thesis, I have exploited these structures to understand various components of galaxies, such as the baryon cycle in dwarf galaxy interactions (Pearson et al. 2016, Pearson et al. 2017b). In this talk, I will focus on my thesis work related to the stellar stream emerging from the old, globular cluster, Palomar 5 (Pal 5), orbiting our own Milky Way. As the stellar stream members were once closely tied together in energy and angular momentum space, we can use their distribution in phase space to trace back where they were once located and what affected them along their paths. In particular, I will show that the mere existence of Pal 5’s thin stream can rule out a moderately triaxial potential model of our Galaxy (Pearson et al. 2015) and that the debris of Pal 5-like streams will spread much further in space in a triaxial potential (a mechanism which I dubbed “stream fanning”) . Additionally, I will show that the Milky Way's Galactic bar, can punch holes in stellar streams and explain the recently discovered length asymmetry between Pal 5’s leading and trailing arm (Pearson et al. 2017a). These holes grow and have locations along stellar streams dependent on the Galactic bar orientation, mass and rotational speed, which provides an intriguing methodology for studying our own Milky Way’s Galactic bar in more detail. The fact that the bar can create under densities in stellar streams, further demonstrates that we should be careful when interpreting gaps in stellar streams as indirect evidence of the existence of dark matter subhalos in our Galaxy.

Do running speed and shoe cushioning influence impact loading and tibial shock in basketball players?

PubMed Central

Liebenberg, Jacobus; Woo, Jeonghyun; Park, Sang-Kyoon; Yoon, Suk-Hoon; Cheung, Roy Tsz-Hei; Ryu, Jiseon

2018-01-01

Background Tibial stress fracture (TSF) is a common injury in basketball players. This condition has been associated with high tibial shock and impact loading, which can be affected by running speed, footwear condition, and footstrike pattern. However, these relationships were established in runners but not in basketball players, with very little research done on impact loading and speed. Hence, this study compared tibial shock, impact loading, and foot strike pattern in basketball players running at different speeds with different shoe cushioning properties/performances. Methods Eighteen male collegiate basketball players performed straight running trials with different shoe cushioning (regular-, better-, and best-cushioning) and running speed conditions (3.0 m/s vs. 6.0 m/s) on a flat instrumented runway. Tri-axial accelerometer, force plate and motion capture system were used to determine tibial accelerations, vertical ground reaction forces and footstrike patterns in each condition, respectively. Comfort perception was indicated on a 150 mm Visual Analogue Scale. A 2 (speed) × 3 (footwear) repeated measures ANOVA was used to examine the main effects of shoe cushioning and running speeds. Results Greater tibial shock (P < 0.001; η2 = 0.80) and impact loading (P < 0.001; η2 = 0.73–0.87) were experienced at faster running speeds. Interestingly, shoes with regular-cushioning or best-cushioning resulted in greater tibial shock (P = 0.03; η2 = 0.39) and impact loading (P = 0.03; η2 = 0.38–0.68) than shoes with better-cushioning. Basketball players continued using a rearfoot strike during running, regardless of running speed and footwear cushioning conditions (P > 0.14; η2 = 0.13). Discussion There may be an optimal band of shoe cushioning for better protection against TSF. These findings may provide insights to formulate rehabilitation protocols for basketball players who are recovering from TSF. PMID:29770274

Learning multiple variable-speed sequences in striatum via cortical tutoring.

PubMed

Murray, James M; Escola, G Sean

2017-05-08

Sparse, sequential patterns of neural activity have been observed in numerous brain areas during timekeeping and motor sequence tasks. Inspired by such observations, we construct a model of the striatum, an all-inhibitory circuit where sequential activity patterns are prominent, addressing the following key challenges: (i) obtaining control over temporal rescaling of the sequence speed, with the ability to generalize to new speeds; (ii) facilitating flexible expression of distinct sequences via selective activation, concatenation, and recycling of specific subsequences; and (iii) enabling the biologically plausible learning of sequences, consistent with the decoupling of learning and execution suggested by lesion studies showing that cortical circuits are necessary for learning, but that subcortical circuits are sufficient to drive learned behaviors. The same mechanisms that we describe can also be applied to circuits with both excitatory and inhibitory populations, and hence may underlie general features of sequential neural activity pattern generation in the brain.

Writing Forces Associated With Four Pencil Grasp Patterns in Grade 4 Children

PubMed Central

Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl

2013-01-01

OBJECTIVE. We investigated differences in handwriting kinetics, speed, and legibility among four pencil grasps after a 10-min copy task. METHOD. Seventy-four Grade 4 students completed a handwriting assessment before and after a copy task. Grip and axial forces were measured with an instrumented stylus and force-sensitive tablet. We used multiple linear regression to analyze the relationship between grasp pattern and grip and axial forces. RESULTS. We found no kinetic differences among grasps, whether considered individually or grouped by the number of fingers on the barrel. However, when grasps were grouped according to the thumb position, the adducted grasps exhibited higher mean grip and axial forces. CONCLUSION. Grip forces were generally similar across the different grasps. Kinetic differences resulting from thumb position seemed to have no bearing on speed and legibility. Interventions for handwriting difficulties should focus more on speed and letter formation than on grasp pattern. PMID:23433277

Stability of a dragged viscous thread: Onset of ``stitching'' in a fluid-mechanical ``sewing machine''

NASA Astrophysics Data System (ADS)

Ribe, Neil M.; Lister, John R.; Chiu-Webster, Sunny

2006-12-01

A thin thread of viscous fluid that falls on a moving belt acts like a fluid-mechanical "sewing machine," exhibiting a rich variety of "stitch" patterns including meanders, translated coiling, slanted loops, braiding, figures-of-eight, W-patterns, side kicks, and period-doubled patterns. Using a numerical linear stability analysis, we determine the critical belt speed and oscillation frequency of the first bifurcation, at which a steady dragged viscous thread becomes unstable to transverse oscillations or "meandering." The predictions of the stability analysis agree closely with the experimental measurements of Chiu-Webster and Lister [J. Fluid Mech. 569, 89 (2006)]. Moreover, the critical belt speed and onset frequency for meandering are nearly identical to the contact-point migration speed and angular frequency, respectively, of steady coiling of a viscous thread on a stationary surface, implying a remarkable degree of dynamical similarity between the two phenomena.

Onset of `stitching' in the fluid mechanical `sewing machine'

NASA Astrophysics Data System (ADS)

Ribe, Neil; Lister, John; Chiu-Webster, Sunny

2006-11-01

A thin thread of viscous fluid that falls on a moving belt acts like a fluid mechanical `sewing machine', exhibiting a rich variety of `stitch' patterns including meanders, side kicks, slanted loops, braiding, figures-of-eight, W-patterns, and period-doubled patterns (Chiu-Webster and Lister, J. Fluid Mech., in press). Using a numerical linear stability analysis based on asymptotic `slender thread' theory, we determine the critical belt speed and frequency of the first bifurcation, at which a steady dragged viscous thread becomes unstable to sideways oscillations (`meanders'). The predictions of the stability analysis agree closely with experimental measurements. Moreover, we find that the critical belt speed and frequency for meandering are nearly identical to the contact point migration speed and the frequency, respectively, of steady coiling of a viscous thread on a stationary surface, implying a remarkable degree of dynamical similarity between the two phenomena.

Do short international layovers allow sufficient opportunity for pilots to recover?

PubMed

Lamond, Nicole; Petrilli, Renée M; Dawson, Drew; Roach, Gregory D

2006-01-01

For Australian pilots, short layovers (<40 h) are a feature of many international patterns. However, anecdotal reports suggest that flight crew members find patterns with short slips more fatiguing than those with a longer international layover, as they restrict the opportunity to obtain sufficient sleep. The current study aimed to determine whether pilots operating international patterns with short layovers have sufficient opportunity to recover prior to the inbound flight. Nineteen international pilots (ten captains, nine first officers) operating a direct return pattern from Australia to Los Angeles (LAX) with a short (n = 9) 9+/-0.8 h (mean+/-S.D) or long (n = 10) 62.2+/-0.9 h LAX layover wore an activity monitor and kept a sleep/duty diary during the pattern. Immediately before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (Palm-PVT). Flights were of comparable duration outbound (3.5+/-0.6 h) and inbound (14.3+/-0.6 h) and timing. The amount of sleep obtained in-flight did not significantly vary as a function of layover length. However, pilots obtained significantly more sleep during the inbound (3.7+/-0.8 h) than the outbound flight (2.2+/-0.8 h). Pilots with the shorter layover obtained significantly less sleep in total during layover (14.0+/-2.7 h vs. 19.6+/-2.5), due to significantly fewer sleep periods (3.0+/-0.7 vs. 4.0+/-0.9). However, neither mean sleep duration nor the sleep obtained in the 24 h prior to the inbound flight significantly differed as a function of layover length. Response speed significantly varied across the pattern, and a significant interaction was also observed. For pilots with a short layover, response speed was significantly slower at the end of both the outbound and inbound flight, and prior to the inbound flight (i.e., at the end of layover), relative to response speed at the start of the pattern (pre-trip). Similarly, response speed for the longer layover was slower at the end of the outbound flight compared to pre-trip (approaching significance, p = 0.073). However, response speed at the beginning of the inbound flight was significantly faster than pre-trip and did not significantly differ from pre-trip at the end of the inbound flight. The data suggest that short slips (<40 h) do not allow pilots the opportunity to obtain sufficient sleep to reverse the effects of fatigue accumulated during the outbound flight. As a result, their response speed prior to the inbound flight is substantially slower than the response speed of flight crew with a longer layover.

A multicomponent nutrient bar promotes weight loss and improves dyslipidemia and insulin resistance in the overweight/obese: Chronic inflammation blunts these improvements

USDA-ARS?s Scientific Manuscript database

Poor diets are a major cause of obesity-associated metabolic dysregulation. It is difficult for many people to change dietary patterns. We hypothesized that dietary-induced metabolic dysregulation, and consequent increased risk of disease, is due in large part to what poor diets are lacking; a nutri...

State of Texas Children 2017: Child Well-Being in the Rio Grande Valley

ERIC Educational Resources Information Center

Tingle, Kristie; Haynes, Madeline; Li, DongMei

2017-01-01

Located on the U.S.-Mexico border, the Rio Grande Valley is a place of rich culture and possibilities. However, on many indicators of children's health, education and financial security, the Valley is not doing as well as Texas overall, revealing a pattern of disinvestment in children's futures. In order to "raise the bar" in child…

Hierarchical micro- and nanofabrication by pattern-directed contact instabilities of thin viscoelastic films

NASA Astrophysics Data System (ADS)

Ghosh, Abir; Bandyopadhyay, Dipankar; Sarkar, Jayati; Sharma, Ashutosh

2017-12-01

A surface of a thin viscoelastic film forms spinodal patterns when brought in contact proximity of another surface due to the dominance of destabilizing intermolecular interaction over the stabilizing elastic and surface tension forces. In this study, we theoretically explore such contact instabilities of a thin viscoelastic film, wherein the patterns generated on the surface of the film is developed with the help of a contactor decorated with periodic physical, chemical, and physicochemical features on the surface. The nonlinear analysis shown here considers the movement of the patterned contactor during the adhesion and debonding processes, which is unlike most of the previous works where the contactor is considered to be stationary. The simulations reveal that the amplitude and periodicity of the patterns decorated on the contactor together with the contactor speed can be the key parameters to stimulate pattern formation on the film surface alongside causing changeover of the various modes of debonding of the surfaces. In particular, the ratio of the elastic to viscous compliances of the film is found to play a critical role to stimulate the changeover of the modes from catastrophic to peeling or coalescence. The study uncovers that a higher wettability contrast across the patterned contactor leads to the catastrophic collapse of the patterns decorated on the film surface when the contactor debonds at a moderate speed. In comparison, a moderately high wettability contrast alongside a faster withdrawal speed of the contactor results in the gradual peeling of columns during the debonding cycle. Remarkably, a higher withdrawal speed of the contactor from the film-proximity can increase the aspect ratio of the patterns fabricated on the film surface to about fourfold during the peeling mode of debonding. The results show the importance of the usage of patterned contactors, their controlled movement, and extent of elastic to viscous compliance ratio of the film for the improvement of the aspect ratio of the patterns developed using the elastic contact lithography of the thin viscoelastic films. The simulations also reveal the possibilities of the fabrication of biomimetic micro- or nanostructures such as columns, holes, cavities, or a combination of these patterns with large-area ordering employing the patterned contactors. A few example cases are shown to highlight the capacity of the proposed methodology for the fabrication of higher aspect ratio hierarchical micro- or nanostructures.

Effect of loading on unintentional lifting velocity declines during single sets of repetitions to failure during upper and lower extremity muscle actions.

PubMed

Izquierdo, M; González-Badillo, J J; Häkkinen, K; Ibáñez, J; Kraemer, W J; Altadill, A; Eslava, J; Gorostiaga, E M

2006-09-01

The purpose of this study was to examine the effect of different loads on repetition speed during single sets of repetitions to failure in bench press and parallel squat. Thirty-six physical active men performed 1-repetition maximum in a bench press (1 RM (BP)) and half squat position (1 RM (HS)), and performed maximal power-output continuous repetition sets randomly every 10 days until failure with a submaximal load (60 %, 65 %, 70 %, and 75 % of 1RM, respectively) during bench press and parallel squat. Average velocity of each repetition was recorded by linking a rotary encoder to the end part of the bar. The values of 1 RM (BP) and 1 RM (HS) were 91 +/- 17 and 200 +/- 20 kg, respectively. The number of repetitions performed for a given percentage of 1RM was significantly higher (p < 0.001) in half squat than in bench press performance. Average repetition velocity decreased at a greater rate in bench press than in parallel squat. The significant reductions observed in the average repetition velocity (expressed as a percentage of the average velocity achieved during the initial repetition) were observed at higher percentage of the total number of repetitions performed in parallel squat (48 - 69 %) than in bench press (34 - 40 %) actions. The major finding in this study was that, for a given muscle action (bench press or parallel squat), the pattern of reduction in the relative average velocity achieved during each repetition and the relative number of repetitions performed was the same for all percentages of 1RM tested. However, relative average velocity decreased at a greater rate in bench press than in parallel squat performance. This would indicate that in bench press the significant reductions observed in the average repetition velocity occurred when the number of repetitions was over one third (34 %) of the total number of repetitions performed, whereas in parallel squat it was nearly one half (48 %). Conceptually, this would indicate that for a given exercise (bench press or squat) and percentage of maximal dynamic strength (1RM), the pattern of velocity decrease can be predicted over a set of repetitions, so that a minimum repetition threshold to ensure maximal speed performance is determined.

Mendigite, Mn2Mn2MnCa(Si3O9)2, a new mineral species of the bustamite group from the Eifel volcanic region, Germany

NASA Astrophysics Data System (ADS)

Chukanov, N. V.; Aksenov, S. M.; Rastsvetaeva, R. K.; Van, K. V.; Belakovskiy, D. I.; Pekov, I. V.; Gurzhiy, V. V.; Schüller, W.; Ternes, B.

2015-12-01

A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). D calc = 3.56 g/cm3. The IR spectrum shows the absence of H2O and OH groups. Mendigite is biaxial (-), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2 V meas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn2+/Mn3+ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn2O3, 4.42 Fe2O3, 1.08 Al2O3, 43.80 SiO2, total 100.82. The empirical formula is Mn2.00(Mn1.33Ca0.67) (Mn0.50 2+ Mn0.28 3+ Fe0.15 3+ Mg0.07)(Ca0.80 (Mn0.20 2+)(Si5.57 Fe0.27 3+ Al0.16O18). The idealized formula is Mn2Mn2MnCa(Si3O9)2. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group Pbar 1; the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) Å3, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), (01bar 2, 1bar 20), 2.885 (100) (221, 2bar 11, 1bar 21), 2.691 (21) (222, 2bar 10), 2.397 (21) (02bar 2, 21bar 1, 203, 031), 1.774 (37) (412, 3bar 21). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1.

Morphodynamics structures induced by variations of the channel width

NASA Astrophysics Data System (ADS)

Duro, Gonzalo; Crosato, Alessandra; Tassi, Pablo

2014-05-01

In alluvial channels, forcing effects, such as a longitudinally varying width, can induce the formation of steady bars (Olesen, 1984). The type of bars that form, such as alternate, central or multiple, will mainly depend on the local flow width-to-depth ratio and on upstream conditions (Struiksma et al., 1985). The effects on bar formation of varying the channel width received attention only recently and investigations, based on flume experiments and mathematical modelling, are mostly restricted to small longitudinal sinusoidal variations of the channel width (e.g. Repetto et al., 2002; Wu and Yeh, 2005, Zolezzi et al., 2012; Frascati and Lanzoni, 2013). In this work, we analyze the variations in equilibrium bed topography in a longitudinal width-varying channel with characteristic scales of the Waal River (The Netherlands) using two different 2D depth-averaged morphodynamic models, one based on the Delft3D code and one on Telemac-Mascaret system. In particular, we explore the effects of changing the wavelength of sinusoidal width variations in a straight channel, focusing on the effects of the spatial lag between bar formation and forcing that is observed in numerical models and laboratory experiments (e.g. Crosato et al, 2011). We extend the investigations to finite width variations in which longitudinal changes of the width-to-depth ratio are such that they may affect the type of bars that become unstable (alternate, central or multiple bars). Numerical results are qualitatively validated with field observations and the resulting morphodynamic pattern is compared with the physics-based predictor of river bar modes by Crosato and Mosselman (2009). The numerical models are finally used to analyse the experimental conditions of Wu and Yeh (2005). The study should be seen as merely exploratory. The aim is to investigate possible approaches for future research aiming at assessing the effects of artificial river widening and narrowing to control bar formation in alluvial rivers. References Crosato A. and Mosselman E., 2009. Simple physics-based predictor for the number of river bars and the transition between meandering and braiding. Water Resources Research, 45, W03424, doi: 10.1029/2008WR007242. Crosato A., Mosselman E., Desta F.B. and Uijttewaal W.S.J., 2011. Experimental and numerical evidence for intrinsic nonmigrating bars in alluvial channels. Water Resources Research, AGU, 47(3), W03511, doi 10.1029/2010WR009714. Frascati A. and Lanzoni S., 2013. A mathematical model for meandering rivers with varying width. J. Geophys. Res.Earth Surf., 118, doi:10.1002/jgrf.20084. Olesen K.W., 1984. Alternate bars in and meandering of alluvial rivers. In: River Meandering, Proc. of the Conf. Rivers '83, 24-26 Oct. 1983, New Orleans, Louisiana, U.S.A., ed. Elliott C.M., pp. 873-884, ASCE, New York. ISBN 0-87262-393-9. Repetto R., Tubino, M. and Paola C., 2002. Planimetric instability of channels with variable width. J. Fluid Mech., 457, 79-109. Struiksma N., Olesen K.W., Flokstra C. and De Vriend H.J., 1985. Bed deformation in curved alluvial channels. J. Hydraul. Res., 23(1), 57- 79. Wu F.-C. and Yeh T.-H., 2005. Forced bars induced by variations of channel width: Implications for incipient bifurcation. J. Geophys. Res., 110, F02009, doi:10.1029/2004JF000160. Zolezzi, G., R. Luchi, and M. Tubino (2012), Modeling morphodynamic processes in meandering rivers with spatial width variations, Rev. Geophys., 50, RG4005, doi:10.1029/2012RG000392.

Discrimination of gender-, speed-, and shoe-dependent movement patterns in runners using full-body kinematics.

PubMed

Maurer, Christian; Federolf, Peter; von Tscharner, Vinzenz; Stirling, Lisa; Nigg, Benno M

2012-05-01

Changes in gait kinematics have often been analyzed using pattern recognition methods such as principal component analysis (PCA). It is usually just the first few principal components that are analyzed, because they describe the main variability within a dataset and thus represent the main movement patterns. However, while subtle changes in gait pattern (for instance, due to different footwear) may not change main movement patterns, they may affect movements represented by higher principal components. This study was designed to test two hypotheses: (1) speed and gender differences can be observed in the first principal components, and (2) small interventions such as changing footwear change the gait characteristics of higher principal components. Kinematic changes due to different running conditions (speed - 3.1m/s and 4.9 m/s, gender, and footwear - control shoe and adidas MicroBounce shoe) were investigated by applying PCA and support vector machine (SVM) to a full-body reflective marker setup. Differences in speed changed the basic movement pattern, as was reflected by a change in the time-dependent coefficient derived from the first principal. Gender was differentiated by using the time-dependent coefficient derived from intermediate principal components. (Intermediate principal components are characterized by limb rotations of the thigh and shank.) Different shoe conditions were identified in higher principal components. This study showed that different interventions can be analyzed using a full-body kinematic approach. Within the well-defined vector space spanned by the data of all subjects, higher principal components should also be considered because these components show the differences that result from small interventions such as footwear changes. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Sociodemographic Disparities in Local Smoke-Free Law Coverage in 10 States.

PubMed

Huang, Jidong; King, Brian A; Babb, Stephen D; Xu, Xin; Hallett, Cynthia; Hopkins, Maggie

2015-09-01

We assessed sociodemographic disparities in local 100% smoke-free laws prohibiting smoking in all indoor areas of nonhospitality worksites, restaurants, and bars in 10 states. We obtained data on local 100% smoke-free laws (US Tobacco Control Laws Database) and subcounty characteristics (2006-2010 American Community Survey) for Alabama, Alaska, Indiana, Kentucky, Mississippi, Missouri, North Dakota, South Carolina, Texas, and West Virginia. Outcomes included (1) 100% smoke-free law covering restaurants, bars, and workplaces; (2) 100% smoke-free law covering restaurants, bars, or workplaces; and (3) number of venue types covered by 100% smoke-free laws (0-3). Sociodemographics included total population, urban status, percentage racial/ethnic minority, per capita income, percentage with high-school diploma, percentage with blue-collar jobs, and percentage of workers who live and work in the same locality. Across states, localities with less-educated residents, smaller proportions of workers living and working in the same locality, or both generally had lower odds of being covered by 100% smoke-free laws. Coverage varied across states for other sociodemographics. Disparities exist in local smoke-free law coverage. Identifying patterns in coverage can inform state efforts to address related disparities.

Loose Cigarette Purchasing and Nondaily Smoking Among Young Adult Bar Patrons in New York City.

PubMed

Guillory, Jamie; Johns, Michael; Farley, Shannon M; Ling, Pamela M

2015-08-01

We examined loose cigarette (loosie) purchasing behavior among young adult (aged 18-26 years) smokers at bars in New York City and factors associated with purchase and use. Between June and December 2013, we conducted cross-sectional surveys (n = 1916) in randomly selected bars and nightclubs. Using multivariable logistic regression models, we examined associations of loose cigarette purchasing and use with smoking frequency, price, social norms, cessation behaviors, and demographics. Forty-five percent (n = 621) of nondaily smokers and 57% (n = 133) of daily smokers had ever purchased a loosie; 15% of nondaily smokers and 4% of daily smokers reported that their last cigarette was a loosie. Nondaily smokers who never smoked daily were more likely than were daily smokers to have last smoked a loosie (odds ratio = 7.27; 95% confidence interval = 2.35, 22.48). Quitting behaviors and perceived approval of smoking were associated with ever purchasing and recently smoking loosies. Loosie purchase and use is common among young adults, especially nondaily smokers. Smoking patterns and attitudes should be considered to reduce loose cigarette purchasing among young adults in New York City.

Loose Cigarette Purchasing and Nondaily Smoking Among Young Adult Bar Patrons in New York City

PubMed Central

Guillory, Jamie; Johns, Michael; Farley, Shannon M.

2015-01-01

Objectives. We examined loose cigarette (loosie) purchasing behavior among young adult (aged 18–26 years) smokers at bars in New York City and factors associated with purchase and use. Methods. Between June and December 2013, we conducted cross-sectional surveys (n = 1916) in randomly selected bars and nightclubs. Using multivariable logistic regression models, we examined associations of loose cigarette purchasing and use with smoking frequency, price, social norms, cessation behaviors, and demographics. Results. Forty-five percent (n = 621) of nondaily smokers and 57% (n = 133) of daily smokers had ever purchased a loosie; 15% of nondaily smokers and 4% of daily smokers reported that their last cigarette was a loosie. Nondaily smokers who never smoked daily were more likely than were daily smokers to have last smoked a loosie (odds ratio = 7.27; 95% confidence interval = 2.35, 22.48). Quitting behaviors and perceived approval of smoking were associated with ever purchasing and recently smoking loosies. Conclusions. Loosie purchase and use is common among young adults, especially nondaily smokers. Smoking patterns and attitudes should be considered to reduce loose cigarette purchasing among young adults in New York City. PMID:25880951

Sociodemographic Disparities in Local Smoke-Free Law Coverage in 10 States

PubMed Central

Huang, Jidong; Babb, Stephen D.; Xu, Xin; Hallett, Cynthia; Hopkins, Maggie

2015-01-01

Objectives. We assessed sociodemographic disparities in local 100% smoke-free laws prohibiting smoking in all indoor areas of nonhospitality worksites, restaurants, and bars in 10 states. Methods. We obtained data on local 100% smoke-free laws (US Tobacco Control Laws Database) and subcounty characteristics (2006–2010 American Community Survey) for Alabama, Alaska, Indiana, Kentucky, Mississippi, Missouri, North Dakota, South Carolina, Texas, and West Virginia. Outcomes included (1) 100% smoke-free law covering restaurants, bars, and workplaces; (2) 100% smoke-free law covering restaurants, bars, or workplaces; and (3) number of venue types covered by 100% smoke-free laws (0–3). Sociodemographics included total population, urban status, percentage racial/ethnic minority, per capita income, percentage with high-school diploma, percentage with blue-collar jobs, and percentage of workers who live and work in the same locality. Results. Across states, localities with less-educated residents, smaller proportions of workers living and working in the same locality, or both generally had lower odds of being covered by 100% smoke-free laws. Coverage varied across states for other sociodemographics. Conclusions. Disparities exist in local smoke-free law coverage. Identifying patterns in coverage can inform state efforts to address related disparities. PMID:26180972

Calculating binding free energies of host-guest systems using the AMOEBA polarizable force field.

PubMed

Bell, David R; Qi, Rui; Jing, Zhifeng; Xiang, Jin Yu; Mejias, Christopher; Schnieders, Michael J; Ponder, Jay W; Ren, Pengyu

2016-11-09

Molecular recognition is of paramount interest in many applications. Here we investigate a series of host-guest systems previously used in the SAMPL4 blind challenge by using molecular simulations and the AMOEBA polarizable force field. The free energy results computed by Bennett's acceptance ratio (BAR) method using the AMOEBA polarizable force field ranked favorably among the entries submitted to the SAMPL4 host-guest competition [Muddana, et al., J. Comput.-Aided Mol. Des., 2014, 28, 305-317]. In this work we conduct an in-depth analysis of the AMOEBA force field host-guest binding thermodynamics by using both BAR and the orthogonal space random walk (OSRW) methods. The binding entropy-enthalpy contributions are analyzed for each host-guest system. For systems of inordinate binding entropy-enthalpy values, we further examine the hydrogen bonding patterns and configurational entropy contribution. The binding mechanism of this series of host-guest systems varies from ligand to ligand, driven by enthalpy and/or entropy changes. Convergence of BAR and OSRW binding free energy methods is discussed. Ultimately, this work illustrates the value of molecular modelling and advanced force fields for the exploration and interpretation of binding thermodynamics.

Separability of stimulus parameter encoding by on-off directionally selective rabbit retinal ganglion cells

PubMed Central

Nowak, Przemyslaw; Dobbins, Allan C.; Gawne, Timothy J.; Grzywacz, Norberto M.

2011-01-01

The ganglion cell output of the retina constitutes a bottleneck in sensory processing in that ganglion cells must encode multiple stimulus parameters in their responses. Here we investigate encoding strategies of On-Off directionally selective retinal ganglion cells (On-Off DS RGCs) in rabbits, a class of cells dedicated to representing motion. The exquisite axial discrimination of these cells to preferred vs. null direction motion is well documented: it is invariant with respect to speed, contrast, spatial configuration, spatial frequency, and motion extent. However, these cells have broad direction tuning curves and their responses also vary as a function of other parameters such as speed and contrast. In this study, we examined whether the variation in responses across multiple stimulus parameters is systematic, that is the same for all cells, and separable, such that the response to a stimulus is a product of the effects of each stimulus parameter alone. We extracellularly recorded single On-Off DS RGCs in a superfused eyecup preparation while stimulating them with moving bars. We found that spike count responses of these cells scaled as independent functions of direction, speed, and luminance. Moreover, the speed and luminance functions were common across the whole sample of cells. Based on these findings, we developed a model that accurately predicted responses of On-Off DS RGCs as products of separable functions of direction, speed, and luminance (r = 0.98; P < 0.0001). Such a multiplicatively separable encoding strategy may simplify the decoding of these cells' outputs by the higher visual centers. PMID:21325684

Properties of Isokinetic Fatigue at Various Movement Speeds in Adult Males.

ERIC Educational Resources Information Center

Clarke, David H.; Manning, James M.

1985-01-01

Eighteen male subjects, aged 20 to 28 years, engaged in three fatigue bouts using an isokinetic dynamometer to measure knee extension contractions. Peak torque varied inversely with movement speed, and the pattern of decrement was independent of speed. Time to peak torque did not change significantly across trials in isokinetic fatigue. (Author/MT)

Scanning digital lithography providing high speed large area patterning with diffraction limited sub-micron resolution

NASA Astrophysics Data System (ADS)

Wen, Sy-Bor; Bhaskar, Arun; Zhang, Hongjie

2018-07-01

A scanning digital lithography system using computer controlled digital spatial light modulator, spatial filter, infinity correct optical microscope and high precision translation stage is proposed and examined. Through utilizing the spatial filter to limit orders of diffraction modes for light delivered from the spatial light modulator, we are able to achieve diffraction limited deep submicron spatial resolution with the scanning digital lithography system by using standard one inch level optical components with reasonable prices. Raster scanning of this scanning digital lithography system using a high speed high precision x-y translation stage and piezo mount to real time adjust the focal position of objective lens allows us to achieve large area sub-micron resolved patterning with high speed (compared with e-beam lithography). It is determined in this study that to achieve high quality stitching of lithography patterns with raster scanning, a high-resolution rotation stage will be required to ensure the x and y directions of the projected pattern are in the same x and y translation directions of the nanometer precision x-y translation stage.

Oriented microtexturing on the surface of high-speed steel cutting tool

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Tarasov, S. Yu.; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

2016-11-01

Microtexturing the metal cutting tool surfaces is a novel technique intended for enhancing the workability of these tools. The microtexturing is used in machining the titanium alloys for air-space applications for reducing the adhesion wear of metal cutting blades. This paper is focused on forming the microtextured dotted, banded and overlapped areas on the surfaces of high-speed steel samples. The treated areas have been examined using laser scanning microscopy for the microtexture pattern and roughness. It has been shown that the microtextured surfaces obtained on the high-speed steel samples were free of cracks. Surface pattern and roughness of all three microtextured areas have been examined and analyzed.

Effects of El Niño-driven changes in wind patterns on North Pacific albatrosses.

PubMed

Thorne, L H; Conners, M G; Hazen, E L; Bograd, S J; Antolos, M; Costa, D P; Shaffer, S A

2016-06-01

Changes to patterns of wind and ocean currents are tightly linked to climate change and have important implications for cost of travel and energy budgets in marine vertebrates. We evaluated how El Niño-Southern Oscillation (ENSO)-driven wind patterns affected breeding Laysan and black-footed albatross across a decade of study. Owing to latitudinal variation in wind patterns, wind speed differed between habitat used during incubation and brooding; during La Niña conditions, wind speeds were lower in incubating Laysan (though not black-footed) albatross habitat, but higher in habitats used by brooding albatrosses. Incubating Laysan albatrosses benefited from increased wind speeds during El Niño conditions, showing increased travel speeds and mass gained during foraging trips. However, brooding albatrosses did not benefit from stronger winds during La Niña conditions, instead experiencing stronger cumulative headwinds and a smaller proportion of trips in tailwinds. Increased travel costs during brooding may contribute to the lower reproductive success observed in La Niña conditions. Furthermore, benefits of stronger winds in incubating habitat may explain the higher reproductive success of Laysan albatross during El Niño conditions. Our findings highlight the importance of considering habitat accessibility and cost of travel when evaluating the impacts of climate-driven habitat change on marine predators. © 2016 The Author(s).

Effects of El Niño-driven changes in wind patterns on North Pacific albatrosses

PubMed Central

Thorne, L. H.; Conners, M. G.; Hazen, E. L.; Bograd, S. J.; Antolos, M.; Costa, D. P.; Shaffer, S. A.

2016-01-01

Changes to patterns of wind and ocean currents are tightly linked to climate change and have important implications for cost of travel and energy budgets in marine vertebrates. We evaluated how El Niño-Southern Oscillation (ENSO)-driven wind patterns affected breeding Laysan and black-footed albatross across a decade of study. Owing to latitudinal variation in wind patterns, wind speed differed between habitat used during incubation and brooding; during La Niña conditions, wind speeds were lower in incubating Laysan (though not black-footed) albatross habitat, but higher in habitats used by brooding albatrosses. Incubating Laysan albatrosses benefited from increased wind speeds during El Niño conditions, showing increased travel speeds and mass gained during foraging trips. However, brooding albatrosses did not benefit from stronger winds during La Niña conditions, instead experiencing stronger cumulative headwinds and a smaller proportion of trips in tailwinds. Increased travel costs during brooding may contribute to the lower reproductive success observed in La Niña conditions. Furthermore, benefits of stronger winds in incubating habitat may explain the higher reproductive success of Laysan albatross during El Niño conditions. Our findings highlight the importance of considering habitat accessibility and cost of travel when evaluating the impacts of climate-driven habitat change on marine predators. PMID:27278360

Positive solutions for nonlocal dispersal equation with spatial degeneracy

NASA Astrophysics Data System (ADS)

Sun, Jian-Wen

2018-02-01

In this paper, we consider the positive solutions of the nonlocal dispersal equation \\int \\limits _{Ω }J(x,y)[u(y)-u(x)]dy=-λ m(x)u(x)+[c(x)+ɛ ]u^p(x) \\quad { in }\\bar{Ω }, where Ω \\subset R^N is a bounded domain, λ ,ɛ and p>1 are positive constants. The dispersal kernel J and the coefficient c( x) are nonnegative, but c( x) has a degeneracy in some subdomain of Ω . In order to study the influence of heterogeneous environment on the nonlocal system, we study the sharp spatial patterns of positive solutions as ɛ → 0. We obtain that the positive solutions always have blow-up asymptotic profiles in \\bar{Ω }. Meanwhile, we find that the profiles in degeneracy domain are different from the domain without degeneracy.

Full-face motorcycle helmet protection from facial impacts: an investigation using THOR dummy impacts and SIMon finite element head model.

PubMed

Whyte, Thomas; Gibson, Tom; Eager, David; Milthorpe, Bruce

2017-06-01

Facial impacts are both common and injurious for helmeted motorcyclists who crash; however, there is no facial impact requirement in major motorcycle helmet standards. This study examined the effect of full-face motorcycle helmet protection on brain injury risk in facial impacts using a test device with biofidelic head and neck motion. A preliminary investigation of energy absorbing foam in the helmet chin bar was carried out. Flat-faced rigid pendulum impacts were performed on a THOR dummy in an unprotected (no helmet) and protected mode (two full-face helmet conditions). The head responses of the dummy were input into the simulated injury monitor finite element head model to analyse the risk of brain injury in these impacts. Full-face helmet protection provides a significant reduction in brain injury risk in facial impacts at increasing impact speeds compared with an unprotected rider (p<0.05). The effect of low-density crushable foam added to the chin bar could not be distinguished from an unpadded chin bar impact. Despite the lack of an impact attenuation requirement for the face, full-face helmets do provide a reduction in head injury risk to the wearer in facial impacts. The specific helmet design factors that influence head injury risk in facial impacts need further investigation if improved protection for helmeted motorcyclists is to be achieved. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Equation of state of Mo from shock compression experiments on preheated samples

NASA Astrophysics Data System (ADS)

Fat'yanov, O. V.; Asimow, P. D.

2017-03-01

We present a reanalysis of reported Hugoniot data for Mo, including both experiments shocked from ambient temperature (T) and those preheated to 1673 K, using the most general methods of least-squares fitting to constrain the Grüneisen model. This updated Mie-Grüneisen equation of state (EOS) is used to construct a family of maximum likelihood Hugoniots of Mo from initial temperatures of 298 to 2350 K and a parameterization valid over this range. We adopted a single linear function at each initial temperature over the entire range of particle velocities considered. Total uncertainties of all the EOS parameters and correlation coefficients for these uncertainties are given. The improved predictive capabilities of our EOS for Mo are confirmed by (1) better agreement between calculated bulk sound speeds and published measurements along the principal Hugoniot, (2) good agreement between our Grüneisen data and three reported high-pressure γ ( V ) functions obtained from shock-compression of porous samples, and (3) very good agreement between our 1 bar Grüneisen values and γ ( T ) at ambient pressure recalculated from reported experimental data on the adiabatic bulk modulus K s ( T ) . Our analysis shows that an EOS constructed from shock compression data allows a much more accurate prediction of γ ( T ) values at 1 bar than those based on static compression measurements or first-principles calculations. Published calibrations of the Mie-Grüneisen EOS for Mo using static compression measurements only do not reproduce even low-pressure asymptotic values of γ ( T ) at 1 bar, where the most accurate experimental data are available.

Enhanced Sampling in Free Energy Calculations: Combining SGLD with the Bennett's Acceptance Ratio and Enveloping Distribution Sampling Methods.

PubMed

König, Gerhard; Miller, Benjamin T; Boresch, Stefan; Wu, Xiongwu; Brooks, Bernard R

2012-10-09

One of the key requirements for the accurate calculation of free energy differences is proper sampling of conformational space. Especially in biological applications, molecular dynamics simulations are often confronted with rugged energy surfaces and high energy barriers, leading to insufficient sampling and, in turn, poor convergence of the free energy results. In this work, we address this problem by employing enhanced sampling methods. We explore the possibility of using self-guided Langevin dynamics (SGLD) to speed up the exploration process in free energy simulations. To obtain improved free energy differences from such simulations, it is necessary to account for the effects of the bias due to the guiding forces. We demonstrate how this can be accomplished for the Bennett's acceptance ratio (BAR) and the enveloping distribution sampling (EDS) methods. While BAR is considered among the most efficient methods available for free energy calculations, the EDS method developed by Christ and van Gunsteren is a promising development that reduces the computational costs of free energy calculations by simulating a single reference state. To evaluate the accuracy of both approaches in connection with enhanced sampling, EDS was implemented in CHARMM. For testing, we employ benchmark systems with analytical reference results and the mutation of alanine to serine. We find that SGLD with reweighting can provide accurate results for BAR and EDS where conventional molecular dynamics simulations fail. In addition, we compare the performance of EDS with other free energy methods. We briefly discuss the implications of our results and provide practical guidelines for conducting free energy simulations with SGLD.

Preparation, patterning, and properties of thin YBa2Cu3O(7-delta) films

NASA Astrophysics Data System (ADS)

de Vries, J. W. C.; Dam, B.; Heijman, M. G. J.; Stollman, G. M.; Gijs, M. A. M.

1988-05-01

High T(c) superconducting thin films were prepared on (100) SrTiO3 substrates by dc triode sputtering and subsequent annealing. In these films Hall-bar structures having a width down to 5 microns were patterned using a reactive ion-etching technique. Superconductivity above 77 K was observed. When compared with the original film there is only a small reduction in T(c). The critical current density determined by electrical measurements is substantially reduced. On the other hand, the critical current density in the bulk of the grains as measured by the torque on a film is not reduced by the patterning process. It is suggested that superconductor-normal metal-superconductor junctions between the grains account for this difference.

Diagnostic techniques in deflagration and detonation studies.

PubMed

Proud, William G; Williamson, David M; Field, John E; Walley, Stephen M

2015-12-01

Advances in experimental, high-speed techniques can be used to explore the processes occurring within energetic materials. This review describes techniques used to study a wide range of processes: hot-spot formation, ignition thresholds, deflagration, sensitivity and finally the detonation process. As this is a wide field the focus will be on small-scale experiments and quantitative studies. It is important that such studies are linked to predictive models, which inform the experimental design process. The stimuli range includes, thermal ignition, drop-weight, Hopkinson Bar and Plate Impact studies. Studies made with inert simulants are also included as these are important in differentiating between reactive response and purely mechanical behaviour.

Wave Fluid Film Bearing Tests for an Aviation Gearbox

NASA Technical Reports Server (NTRS)

Dimofte, Florin; Proctor, Margaret P.; Fleming, David P.; Keith, Theo G., Jr.

2000-01-01

An oil-lubricated wave journal-thrust bearing assembly was successfully tested at conditions found in general aviation engine gearboxes. The bearing performed well at both steady state conditions and in start-stop tests. It ran stably under all loading conditions, including zero load, at all speeds up to 16 000 rpm. The bearing carried 25 percent more load than required for the gearbox application, supporting 8900 N (94 bars average pressure), and showed very good thermal stability. 450 start-stop cycles were also performed, including 350 cycles without oil supply during starting and stopping. Test results and numerical predictions were in good agreement.

NASA Glenn Icing Research Tunnel: 2014 Cloud Calibration Procedure and Results

NASA Technical Reports Server (NTRS)

Van Zante, Judith F.; Ide, Robert F.; Steen, Laura E.; Acosta, Waldo J.

2014-01-01

The results of the December 2013 to February 2014 Icing Research Tunnel full icing cloud calibration are presented. The calibration steps included establishing a uniform cloud and conducting drop size and liquid water content calibrations. The goal of the calibration was to develop a uniform cloud, and to generate a transfer function from the inputs of air speed, spray bar atomizing air pressure and water pressure to the outputs of median volumetric drop diameter and liquid water content. This was done for both 14 CFR Parts 25 and 29, Appendix C ('typical' icing) and soon-to-be released Appendix O (supercooled large drop) conditions.

NASA Glenn Icing Research Tunnel: Upgrade and Cloud Calibration

NASA Technical Reports Server (NTRS)

VanZante, Judith Foss; Ide, Robert F.; Steen, Laura E.

2012-01-01

In 2011, NASA Glenn s Icing Research Tunnel underwent a major modification to it s refrigeration plant and heat exchanger. This paper presents the results of the subsequent full cloud calibration. Details of the calibration procedure and results are presented herein. The steps include developing a nozzle transfer map, establishing a uniform cloud, conducting a drop sizing calibration and finally a liquid water content calibration. The goal of the calibration is to develop a uniform cloud, and to build a transfer map from the inputs of air speed, spray bar atomizing air pressure and water pressure to the output of median volumetric droplet diameter and liquid water content.

NASA Glenn Icing Research Tunnel: 2012 Cloud Calibration Procedure and Results

NASA Technical Reports Server (NTRS)

VanZante, Judith Foss; Ide, Robert F.; Steen, Laura E.

2012-01-01

In 2011, NASA Glenn s Icing Research Tunnel underwent a major modification to it s refrigeration plant and heat exchanger. This paper presents the results of the subsequent full cloud calibration. Details of the calibration procedure and results are presented herein. The steps include developing a nozzle transfer map, establishing a uniform cloud, conducting a drop sizing calibration and finally a liquid water content calibration. The goal of the calibration is to develop a uniform cloud, and to build a transfer map from the inputs of air speed, spray bar atomizing air pressure and water pressure to the output of median volumetric droplet diameter and liquid water content.

The fall of a viscous thread onto a moving surface: a ‘fluid-mechanical sewing machine’

NASA Astrophysics Data System (ADS)

Chiu-Webster, S.; Lister, J. R.

2006-12-01

A viscous thread falling onto a steadily moving horizontal belt shows a surprisingly complex range of behaviour in experiments. Low belt speeds produce coiling, as might be expected from the behaviour of a thread falling onto a stationary surface. High belt speeds produce a steady thread, whose shape is predicted well by theory developed to describe a stretching viscous catenary with surface tension and inertia. Intermediate belt speeds show several novel modes of oscillation, which lay down a wide variety of patterns on the belt. The patterns include meanders, side kicks, slanted loops, braiding, figures-of-eight, Ws, and also period-doubled versions of figures-of-eight, meanders and coiling. The experimental boundary between steady and unsteady behaviour occurs at a slightly lower belt speed than the loss of the steady solution for a stretching catenary.

Comprehensive quantitative investigation of arm swing during walking at various speed and surface slope conditions.

PubMed

Hejrati, Babak; Chesebrough, Sam; Bo Foreman, K; Abbott, Jake J; Merryweather, Andrew S

2016-10-01

Previous studies have shown that inclusion of arm swing in gait rehabilitation leads to more effective walking recovery in patients with walking impairments. However, little is known about the correct arm-swing trajectories to be used in gait rehabilitation given the fact that changes in walking conditions affect arm-swing patterns. In this paper we present a comprehensive look at the effects of a variety of conditions on arm-swing patterns during walking. The results describe the effects of surface slope, walking speed, and physical characteristics on arm-swing patterns in healthy individuals. We propose data-driven mathematical models to describe arm-swing trajectories. Thirty individuals (fifteen females and fifteen males) with a wide range of height (1.58-1.91m) and body mass (49-98kg), participated in our study. Based on their self-selected walking speed, each participant performed walking trials with four speeds on five surface slopes while their whole-body kinematics were recorded. Statistical analysis showed that walking speed, surface slope, and height were the major factors influencing arm swing during locomotion. The results demonstrate that data-driven models can successfully describe arm-swing trajectories for normal gait under varying walking conditions. The findings also provide insight into the behavior of the elbow during walking. Copyright © 2016. Published by Elsevier B.V.

Movement patterns for a critically endangered species, the leatherback turtle (Dermochelys coriacea), linked to foraging success and population status.

PubMed

Bailey, Helen; Fossette, Sabrina; Bograd, Steven J; Shillinger, George L; Swithenbank, Alan M; Georges, Jean-Yves; Gaspar, Philippe; Strömberg, K H Patrik; Paladino, Frank V; Spotila, James R; Block, Barbara A; Hays, Graeme C

2012-01-01

Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for leatherback turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d(-1)) and transit at high speeds (20-45 km d(-1)). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d(-1) indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific turtles. The most parsimonious explanation for these findings is that Eastern Pacific turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic.

A Critical Characteristic in the Transverse Galloping Pattern

PubMed Central

Wei, Xiaohui; Long, Yongjun; Wang, Chunlei; Wang, Shigang

2015-01-01

Transverse gallop is a common gait used by a large number of quadrupeds. This paper employs the simplified dimensionless quadrupedal model to discuss the underlying mechanism of the transverse galloping pattern. The model is studied at different running speeds and different values of leg stiffness, respectively. If the horizontal running speed reaches up to a critical value at a fixed leg stiffness, or if the leg stiffness reaches up to a critical value at a fixed horizontal speed, a key property would emerge which greatly reduces the overall mechanical forces of the dynamic system in a proper range of initial pitch angular velocities. Besides, for each horizontal speed, there is an optimal stiffness of legs that can reduce both the mechanical loads and the metabolic cost of transport. Furthermore, different body proportions and landing distance lags of a pair of legs are studied in the transverse gallop. We find that quadrupeds with longer length of legs compared with the length of the body are more suitable to employ the transverse galloping pattern, and the landing distance lag of a pair of legs could reduce the cost of transport and the locomotion frequency. PMID:27087773

Movement Patterns for a Critically Endangered Species, the Leatherback Turtle (Dermochelys coriacea), Linked to Foraging Success and Population Status

PubMed Central

Bailey, Helen; Fossette, Sabrina; Bograd, Steven J.; Shillinger, George L.; Swithenbank, Alan M.; Georges, Jean-Yves; Gaspar, Philippe; Strömberg, K. H. Patrik; Paladino, Frank V.; Spotila, James R.; Block, Barbara A.; Hays, Graeme C.

2012-01-01

Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for leatherback turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d−1) and transit at high speeds (20–45 km d−1). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d−1 indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific turtles. The most parsimonious explanation for these findings is that Eastern Pacific turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic. PMID:22615767

Expression of c-Fos in the rat retrosplenial cortex during instrumental re-learning of appetitive bar-pressing depends on the number of stages of previous training

PubMed Central

Svarnik, Olga E.; Bulava, Alexandra I.; Alexandrov, Yuri I.

2013-01-01

Learning is known to be accompanied by induction of c-Fos expression in cortical neurons. However, not all neurons are involved in this process. What the c-Fos expression pattern depends on is still unknown. In the present work we studied whether and to what degree previous animal experience about Task 1 (the first phase of an instrumental learning) influenced neuronal c-Fos expression in the retrosplenial cortex during acquisition of Task 2 (the second phase of an instrumental learning). Animals were progressively shaped across days to bar-press for food at the left side of the experimental chamber (Task 1). This appetitive bar-pressing behavior was shaped by nine stages (“9 stages” group), five stages (“5 stages” group) or one intermediate stage (“1 stage” group). After all animals acquired the first skill and practiced it for five days, the bar and feeder on the left, familiar side of the chamber were inactivated, and the animals were allowed to learn a similar instrumental task at the opposite side of the chamber using another pair of a bar and a feeder (Task 2). The highest number of c-Fos positive neurons was found in the retrosplenial cortex of “1 stage” animals as compared to the other groups. The number of c-Fos positive neurons in “5 stages” group animals was significantly lower than in “1 stage” animals and significantly higher than in “9 stages” animals. The number of c-Fos positive neurons in the cortex of “9 stages” animals was significantly higher than in home caged control animals. At the same time, there were no significant differences between groups in such behavioral variables as the number of entrees into the feeder or bar zones during Task 2 learning. Our results suggest that c-Fos expression in the retrosplenial cortex during Task 2 acquisition was influenced by the previous learning history. PMID:23847484

Multiple voluminous sector collapses at Volcán Barú, Panama

NASA Astrophysics Data System (ADS)

Herrick, J. A.; Rose, W. I.

2010-12-01

Our recent work on Volcán Barú, an andesitic dome complex in Western Panama, has revealed a significant hazard from debris avalanches. Field observations of volcanic debris avalanche deposits and study of aerial photo data have revealed two avalanche units from Barú, the Barriles and the Caisán Deposits, both attributed to sector collapse of the western flank. Sherrod and others, 2007, also recognized this as one of the potential volcanic hazards of Panama's youngest volcanic center. The Barriles Deposit yielded two radiocarbon ages: 8590 ±50 ybp and 8000 ±30 ybp. The Caisán Deposit was also dated and is beyond the radiocarbon range (>43,000 ybp). From satellite imagery and field observations of distal hummocks, the total runout length of the Caisán deposit was ˜50 km covering 1180-km2. The Barriles Deposit extended to about 43 km. Despite heavy vegetation of the field area, 576-km2 were analyzed and over 4000 individual hummocks were digitized from aerial photography. Statistical analysis of hummock locations and geometries depict flow patterns over the entire debris fan and reflect the effects of underlying topography. The Barriles avalanche deposit has an estimated volume of 39 km3 to 61 km3 while the Caisán Deposit is slightly larger: 57 km3 to 64 km3. We conclude that debris avalanches of Volcán Barú are rare examples of unconfined volcanic debris avalanche deposits that rank among the world's most voluminous such as ancestral Mount Shasta, USA; Socompa, Chile/Argentina; and Shiveluch, Russia. Supported by the NSF Partnerships in International Research and Education Grant [0530109] this work is part of an on-going collaboration between the Michigan Tech Geology Department and Peace Corps. Reference: Sherrod, D.R., Vallance, J.W., Tapia Espinosa, A., and McGeehin, J.P., 2007, Volcán Barú eruptive history and volcano-hazards assessment, Open-File Report 2007-1401: Reston, VA, The U.S. Geological Survey, p. 33. A view East into the crater of Volcán Barú, Panama. The modern dome marks the highest elevation within the breached rim.

Interactions between Point Bar Growth and Bank Erosion on a Low Sinuosity Meander Bend in an Ephemeral Channel: Insights from Repeat Topographic Surveys and Numerical Modeling

NASA Astrophysics Data System (ADS)

Ursic, M.; Langendoen, E. J.

2017-12-01

Interactions between point bar growth, bank migration, and hydraulics on meandering rivers are complicated and not well understood. For ephemeral streams, rapid fluctuations in flow further complicate studying and understanding these interactions. This study seeks to answer the following `cause-and-effect' question: Does point bar morphologic adjustment determine where bank erosion occurs (for example, through topographic steering of the flow), or does local bank retreat determine where accretion/erosion occurs on the point bar, or do bank erosion and point bar morphologic adjustment co-evolve? Further, is there a response time between the `cause-and-effect' processes and what variables determine its magnitude and duration? In an effort to answer these questions for an ephemeral stream, a dataset of forty-eight repeat topographic surveys over a ten-year period (1996-2006) of a low sinuosity bend within the Goodwin Creek Experimental Watershed, located near Batesville, MS, were utilized in conjunction with continuous discharge measurements to correlate flow variability and erosional and depositional zones, spatially and temporally. Hydraulically, the bend is located immediately downstream of a confluence with a major tributary. Supercritical flumes on both the primary and tributary channels just upstream of the confluence provide continuous measured discharges to the bend over the survey period. In addition, water surface elevations were continuously measured at the upstream and downstream ends of the bend. No spatial correlation trends could be discerned between reach-scale bank retreat, point bar morphologic adjustment, and flow discharge. Because detailed flow patterns were not available, the two-dimensional computer model Telemac2D was used to provide these details. The model was calibrated and validated for a set of runoff events for which more detailed flow data were available. Telemac2D simulations were created for each topographic survey period. Flows greater than baseflow were combined to create contiguous hydrographs for each survey period. Statistical examination of local flow variability and morphological changes throughout the bend will be conducted and presented.

Mixed fluvial systems of Messak Sandstone, a deposit of Nubian lithofacies, southwestern Libya

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorenz, J.C.

1987-05-01

The Messak Sandstone is a coarse to pebbly, tabular cross-bedded, Lower Cretaceous deposit of the widespread Nubian lithofacies. It was deposited at the northern edge of the Murzuq basin in southwestern Libya. Although the sedimentary record is predominantly one of braided fluvial systems, a common subfacies within the formation is interpreted to record the passage of straight-crested sand waves across laterally migrating point bars in sinuous rivers, similar to the pattern documented by Singh and Kumar on the modern Ganga and Yamuna Rivers. Because the sand waves were larger on the lower parts of the point bars, lateral migration createdmore » diagnostic thinning-upward, unidirectional cosets of tabular cross-beds as well as fining-upward, grain-size trends. Common, thick, interbedded claystones, deposited in associated paludal and lacustrine environments, and high variance in cross-bed dispersion patterns also suggest the local presence of sinuous fluvial systems within the overall braided regime. The Messak Sandstone contains some of the features that led Harms et al to propose an unconventional low-sinuosity fluvial environment for the Nubian lithofacies in Egypt, and the continuously high water levels of this model may explain channel-scale clay drapes and overturned cross-beds in the Messak. However, most of the Messak characteristics are incompatible with the low-sinuosity model, suggesting instead that the fluvial channels in the Murzuq basin alternated between braided and high-sinuosity patterns.« less

Unexpected recovery after robotic locomotor training at physiologic stepping speed: a single-case design.

PubMed

Spiess, Martina R; Jaramillo, Jeffrey P; Behrman, Andrea L; Teraoka, Jeffrey K; Patten, Carolynn

2012-08-01

To investigate the effect of walking speed on the emergence of locomotor electromyogram (EMG) patterns in an individual with chronic incomplete spinal cord injury (SCI), and to determine whether central pattern generator activity during robotic locomotor training (RLT) transfers to volitional EMG activity during overground walking. Single-case (B-A-B; experimental treatment-withdrawal-experimental treatment) design. Freestanding rehabilitation research center. A 50-year-old man who was nonambulatory for 16 months after incomplete SCI (sub-T11). The participant completed two 6-week blocks of RLT, training 4 times per week for 30 minutes per session at walking speeds up to 5km/h (1.4m/s) over continuous bouts lasting up to 17 minutes. Surface EMG was recorded weekly during RLT and overground walking. The Walking Index for Spinal Cord Injury (WISCI-II) was assessed daily during training blocks. During week 4, reciprocal, patterned EMG emerged during RLT. EMG amplitude modulation revealed a curvilinear relationship over the range of walking speeds from 1.5 to 5km/h (1.4m/s). Functionally, the participant improved from being nonambulatory (WISCI-II 1/20), to walking overground with reciprocal stepping using knee-ankle-foot orthoses and a walker (WISCI-II 9/20). EMG was also observed during overground walking. These functional gains were maintained greater than 4 years after locomotor training (LT). Here we report an unexpected course of locomotor recovery in an individual with chronic incomplete SCI. Through RLT at physiologic walking speeds, it was possible to activate the central pattern generator even 16 months postinjury. Further, to a certain degree, improvements from RLT transferred to overground walking. Our results suggest that LT-induced changes affect the central pattern generator and allow supraspinal inputs to engage residual spinal pathways. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Prospects of discovering stable double-heavy tetraquarks at a Tera-Z factory

NASA Astrophysics Data System (ADS)

Ali, Ahmed; Parkhomenko, Alexander Ya.; Qin, Qin; Wang, Wei

2018-07-01

Motivated by a number of theoretical considerations, predicting the deeply bound double-heavy tetraquarks T[ u bar d bar ]{ bb }, T[ u bar s bar ]{ bb } and T[ d bar s bar ]{ bb }, we explore the potential of their discovery at Tera-Z factories. Using the process Z → b b bar b b bar , we calculate, employing the Monte Carlo generators MadGraph5_aMC@NLO and Pythia6, the phase space configuration in which the bb pair is likely to fragment as a diquark. In a jet-cone, defined by an invariant mass interval mbb < M T[ q bar qbar‧ ]{ bb } + ΔM, the sought-after tetraquarks T[ q bar qbar‧ ]{ bb } as well as the double-bottom baryons, Ξbb0,-, and Ωbb- , can be produced. Using the heavy quark-diquark symmetry, we estimate B (Z → T[ u bar d bar ]{ bb } + b bar b bar) = (1.2-0.3+1.0) ×10-6, and about a half of this for the T[ u bar s bar ]{ bb } and T[ d bar s bar ]{ bb } . We also present an estimate of their lifetimes using the heavy quark expansion, yielding τ (T[ q bar qbar‧ ]{ bb }) ≃ 800 fs. Measuring the tetraquark masses would require decays, such as T[ u bar d bar ]{ bb } - →B-D-π+, T [ u bar d bar ]{ bb } - → J / ψK‾0B-, T[ u bar d bar ]{ bb } - → J / ψK-B‾0, T[ u bar s bar ]{ bb } - → Ξbc0 Σ-, and T[ d bar s bar ]{ bb } 0 → Ξbc0 Σbar0, with subsequent decay chains in exclusive non-leptonic final states. We estimate a couple of the decay widths and find that the product branching ratios do not exceed 10-5. Hence, a good fraction of these modes will be required for a discovery of T[ q bar qbar‧ ]{ bb } at a Tera-Z factory.

Sedimentary Facies and Stratigraphy of the Changjiang (Yangtze River) Delta

NASA Astrophysics Data System (ADS)

Dalrymple, R. W.; Zhang, X.; Lin, C. M.

2017-12-01

A disproportionate number of the world's largest deltas are tide-dominated or strongly tide-influenced, in part because the low gradient of these rivers allows the tide to penetrate far inland, generating strong tidal currents at the river mouth. These deltas also tend to be mud-dominated because a significant fraction of the bedload is trapped farther inland. Despite their great importance as sediment depo-centers, as analogues for ancient sedimentary successions, and as areas of intense human occupation, they are the most poorly understood coastal system. The Changjiang (Yangtze River), the 4th largest river in the world in terms of sediment discharge, is one such tide-dominated system, with a mean tidal range of 2.7 m and tidal-current speeds of 1 m/s at its mouth. It shows a fairly typical series of low-relief channels and bars in the mouth-bar area and passes seaward and down-drift into a coastal mud belt that extends 800 km to the south of the river mouth. The deposits from both the transgressive-phase and modern delta are all dominated by mud, except for the fluvial-channel deposits that are clean sand. Channel-floor deposits in areas with appreciable tidal influence contain abundant fluid-mud layers (1-3 cm thick), intercalated with relatively coarse sand; such mud layers show evidence of tidal cyclicity. The overlying tidal-bar deposits commonly become sandier upward because of the upward loss of fluid-mud layers. The tidal channels and bars that characterize the mouth-bar and delta-front area are dominated by randomly organized structureless mud layers, 5-30 cm thick, that are interpreted to be storm-generated fluid-mud deposits. These mud layers become less abundant upward, generating upward-sanding successions. These facies are very similar to those seen in the Amazon and Fly River deltas, suggesting that this is a common motif, and indicating the importance of fluid mud in the dynamics of such systems. Facies proximality can be determined by careful comparison of sand-size trends, tidal mud-layer thicknesses (relative to the turbidity maximum) and the abundance of wave-generated fluid-mud layers. Application of these concepts shows that the transgressive phase of the delta consists of three retrogradationally stacked parasequences, each 7-15 m thick, overlain by the 40 m-thick highstand delta.

The Development of the Text Reception Threshold Test: A Visual Analogue of the Speech Reception Threshold Test

ERIC Educational Resources Information Center

Zekveld, Adriana A.; George, Erwin L. J.; Kramer, Sophia E.; Goverts, S. Theo; Houtgast, Tammo

2007-01-01

Purpose: In this study, the authors aimed to develop a visual analogue of the widely used Speech Reception Threshold (SRT; R. Plomp & A. M. Mimpen, 1979b) test. The Text Reception Threshold (TRT) test, in which visually presented sentences are masked by a bar pattern, enables the quantification of modality-aspecific variance in speech-in-noise…

Patterns of Global Terrorism 2003

DTIC Science & Technology

2004-04-01

leader Abu Bakar Bashir in August. Thailand’s domestic and international counterterrorism efforts, which were bolstered in the wake of the deadly...efforts to put JI leaders behind bars. On 2 September, the Central Jakarta District Court convicted the spiritual leader of JI, Abu Bakar Bashir...Changi Airport. Singapore also facilitated video testimony of three of its ISA detainees in the Indonesian trial 29 of JI spiritual leader Abu Bakar

Patterns, Trends, and Meanings of Drug Use by Dance-Drug Users in Edinburgh, Scotland

ERIC Educational Resources Information Center

Riley, Sarah C. E.; Hayward, Emma

2004-01-01

A survey of drug use in the past year was completed by 124 clubbers (50% male, 50% female, age range 14-44, mean 24 years). Participants were self selecting and recruited in clubs and pre-club bars. Prevalence rates for alcohol, cannabis, and ecstasy were over 80%; 63% reported cocaine and 53% amphetamine use, 15%-43% used ketamine, psilocybin,…

Expression of emotion in the kinematics of locomotion.

PubMed

Barliya, Avi; Omlor, Lars; Giese, Martin A; Berthoz, Alain; Flash, Tamar

2013-03-01

Here, we examine how different emotions-happiness, fear, sadness and anger-affect the kinematics of locomotion. We focus on a compact representation of locomotion properties using the intersegmental law of coordination (Borghese et al. in J Physiol 494(3):863-879, 1996), which states that, during the gait cycle of human locomotion, the elevation angles of the thigh, shank and foot do not evolve independently of each other but form a planar pattern of co-variation. This phenomenon is highly robust and has been extensively studied. The orientation of the plane has been correlated with changes in the speed of locomotion and with reduction in energy expenditure as speed increases. An analytical model explaining the conditions underlying the emergence of this plane and predicting its orientation reveals that it suffices to examine the amplitudes of the elevation angles of the different segments along with the phase shifts between them (Barliya et al. in Exp Brain Res 193:371-385, 2009). We thus investigated the influence of different emotions on the parameters directly determining the orientation of the intersegmental plane and on the angular rotation profiles of the leg segments, examining both the effect of changes in walking speed and effects independent of speed. Subjects were professional actors and naïve subjects with no training in acting. As expected, emotions were found to strongly affect the kinematics of locomotion, particularly walking speed. The intersegmental coordination patterns revealed that emotional expression caused additional modifications to the locomotion patterns that could not be explained solely by a change in speed. For all emotions except sadness, the amplitude of thigh elevation angles changed from those in neutral locomotion. The intersegmental plane was also differently oriented, especially during anger. We suggest that, while speed is the dominant variable allowing discrimination between different emotional gaits, emotion can be reliably recognized in locomotion only when speed is considered together with these kinematic changes.

Flow Structure and Channel Morphology at a Confluent-Meander Bend

NASA Astrophysics Data System (ADS)

Riley, J. D.; Rhoads, B. L.

2009-12-01

Flow structure and channel morphology in meander bends have been well documented. Channel curvature subjects flow through a bend to centrifugal acceleration, inducing a counterbalancing pressure-gradient force that initiates secondary circulation. Transverse variations in boundary shear stress and bedload transport parallel cross-stream movement of high velocity flow and determine spatial patterns of erosion along the outer bank and deposition along the inner bank. Laboratory experiments and numerical modeling of confluent-meander bends, a junction planform that develops when a tributary joins a meandering river along the outer bank of a bend, suggest that flow and channel morphology in such bends deviate from typical patterns. The purpose of this study is to examine three-dimensional (3-D) flow structure and channel morphology at a natural confluent-meander bend. Field data were collected in southeastern Illinois where Big Muddy Creek joins the Little Wabash River near a local maximum of curvature along an elongated meander loop. Measurements of 3-D velocity components were obtained with an acoustic Doppler current profiler (ADCP) for two flow events with differing momentum ratios. Channel bathymetry was also resolved from the four-beam depths of the ADCP. Analysis of velocity data reveals a distinct shear layer flanked by dual helical cells within the bend immediately downstream of the confluence. Flow from the tributary confines flow from the main channel along the inner part of the channel cross section, displacing the thalweg inward, limiting the downstream extent of the point bar, protecting the outer bank from erosion and enabling bar-building along this bank. Overall, this pattern of flow and channel morphology is quite different from typical patterns in meander bends, but is consistent with a conceptual model derived from laboratory experiments and numerical modeling.

The habitual meal and snacking patterns of university students in two countries and their use of vending machines.

PubMed

Spanos, D; Hankey, C R

2010-02-01

Dietary patterns and food choices in western and northern European countries can differ from those in countries that surround the Mediterranean basin. However, irregular meal patterns and the consumption of high-energy snacks tend to become common in most countries and their association with the prevalence of obesity has been examined in many studies. The first aim of the present study was to describe the habitual meal and snack intakes, including the use of vending machines, for two groups of first-year university students in two countries of different cultural backgrounds. The second aim was to explore the relationships between body mass index (BMI) and snacking for these two groups. One hundred and sixty first-year undergraduate university students from two defined universities in Greece (n = 80) and Scotland (n = 80) volunteered to complete a food frequency questionnaire (FFQ). The FFQ comprised 16 questions assessing their meal and snacking habits. Self-assessed height and weight data were collected. The majority of the 160 students reported a BMI in the healthy range (<25 kg m(-2)). Overall, 26% of the students reported never consuming breakfast. More Scottish students (74%) used vending machines (P < 0.05). More Scottish students consumed chocolate bars and crisps than Greek students (41% and 34% versus 37.5% and 20%, respectively). Only the choice of chocolate bars from vending machines and the consumption of crisps and low fat yogurts were related to BMI (P < 0.05) for both groups. University students living in different countries report similar dietary patterns but differ in their snacking habits. No relationships were found between BMI and snacking. There is a need to carry out research to further our understanding of this relationship.

Variation in Foot Strike Patterns during Running among Habitually Barefoot Populations

PubMed Central

Hatala, Kevin G.; Dingwall, Heather L.; Wunderlich, Roshna E.; Richmond, Brian G.

2013-01-01

Endurance running may have a long evolutionary history in the hominin clade but it was not until very recently that humans ran wearing shoes. Research on modern habitually unshod runners has suggested that they utilize a different biomechanical strategy than runners who wear shoes, namely that barefoot runners typically use a forefoot strike in order to avoid generating the high impact forces that would be experienced if they were to strike the ground with their heels first. This finding suggests that our habitually unshod ancestors may have run in a similar way. However, this research was conducted on a single population and we know little about variation in running form among habitually barefoot people, including the effects of running speed, which has been shown to affect strike patterns in shod runners. Here, we present the results of our investigation into the selection of running foot strike patterns among another modern habitually unshod group, the Daasanach of northern Kenya. Data were collected from 38 consenting adults as they ran along a trackway with a plantar pressure pad placed midway along its length. Subjects ran at self-selected endurance running and sprinting speeds. Our data support the hypothesis that a forefoot strike reduces the magnitude of impact loading, but the majority of subjects instead used a rearfoot strike at endurance running speeds. Their percentages of midfoot and forefoot strikes increased significantly with speed. These results indicate that not all habitually barefoot people prefer running with a forefoot strike, and suggest that other factors such as running speed, training level, substrate mechanical properties, running distance, and running frequency, influence the selection of foot strike patterns. PMID:23326341

Variation in foot strike patterns during running among habitually barefoot populations.

PubMed

Hatala, Kevin G; Dingwall, Heather L; Wunderlich, Roshna E; Richmond, Brian G

2013-01-01

Endurance running may have a long evolutionary history in the hominin clade but it was not until very recently that humans ran wearing shoes. Research on modern habitually unshod runners has suggested that they utilize a different biomechanical strategy than runners who wear shoes, namely that barefoot runners typically use a forefoot strike in order to avoid generating the high impact forces that would be experienced if they were to strike the ground with their heels first. This finding suggests that our habitually unshod ancestors may have run in a similar way. However, this research was conducted on a single population and we know little about variation in running form among habitually barefoot people, including the effects of running speed, which has been shown to affect strike patterns in shod runners. Here, we present the results of our investigation into the selection of running foot strike patterns among another modern habitually unshod group, the Daasanach of northern Kenya. Data were collected from 38 consenting adults as they ran along a trackway with a plantar pressure pad placed midway along its length. Subjects ran at self-selected endurance running and sprinting speeds. Our data support the hypothesis that a forefoot strike reduces the magnitude of impact loading, but the majority of subjects instead used a rearfoot strike at endurance running speeds. Their percentages of midfoot and forefoot strikes increased significantly with speed. These results indicate that not all habitually barefoot people prefer running with a forefoot strike, and suggest that other factors such as running speed, training level, substrate mechanical properties, running distance, and running frequency, influence the selection of foot strike patterns.

Wear Characterization of Carbon Nanotubes Reinforced Acetal Spur, Helical, Bevel and Worm Gears Using a TS Universal Test Rig

NASA Astrophysics Data System (ADS)

Yousef, Samy; Osman, T. A.; Abdalla, Abdelrahman H.; Zohdy, Gamal A.

2015-12-01

Although the applications of nanotechnologies are increasing, there remains a significant barrier between nanotechnology and machine element applications. This work aims to remove this barrier by blending carbon nanotubes (CNT) with common types of acetal polymer gears (spur, helical, bevel and worm). This was done by using adhesive oil (paraffin) during injection molding to synthesize a flange and short bars containing 0.02% CNT by weight. The flanges and short bars were machined using hobbing and milling machines to produce nanocomposite polymer gears. Some defects that surfaced in previous work, such as the appearance of bubbles and unmelted pellets during the injection process, were avoided to produce an excellent dispersion of CNT in the acetal. The wear resistances of the gears were measured by using a TS universal test rig using constant parameters for all of the gears that were fabricated. The tests were run at a speed of 1420 rpm and a torque of 4 Nm. The results showed that the wear resistances of the CNT/acetal gears were increased due to the addition of CNT, especially the helical, bevel and worm gears.

Alert Response to Motion Onset in the Retina

PubMed Central

Chen, Eric Y.; Marre, Olivier; Fisher, Clark; Schwartz, Greg; Levy, Joshua; da Silveira, Rava Azeredo

2013-01-01

Previous studies have shown that motion onset is very effective at capturing attention and is more salient than smooth motion. Here, we find that this salience ranking is present already in the firing rate of retinal ganglion cells. By stimulating the retina with a bar that appears, stays still, and then starts moving, we demonstrate that a subset of salamander retinal ganglion cells, fast OFF cells, responds significantly more strongly to motion onset than to smooth motion. We refer to this phenomenon as an alert response to motion onset. We develop a computational model that predicts the time-varying firing rate of ganglion cells responding to the appearance, onset, and smooth motion of a bar. This model, termed the adaptive cascade model, consists of a ganglion cell that receives input from a layer of bipolar cells, represented by individual rectified subunits. Additionally, both the bipolar and ganglion cells have separate contrast gain control mechanisms. This model captured the responses to our different motion stimuli over a wide range of contrasts, speeds, and locations. The alert response to motion onset, together with its computational model, introduces a new mechanism of sophisticated motion processing that occurs early in the visual system. PMID:23283327

Application of Optical Measurement Techniques During Stages of Pregnancy: Use of Phantom High Speed Cameras for Digital Image Correlation (D.I.C.) During Baby Kicking and Abdomen Movements

NASA Technical Reports Server (NTRS)

Gradl, Paul

2016-01-01

Paired images were collected using a projected pattern instead of standard painting of the speckle pattern on her abdomen. High Speed cameras were post triggered after movements felt. Data was collected at 120 fps -limited due to 60hz frequency of projector. To ensure that kicks and movement data was real a background test was conducted with no baby movement (to correct for breathing and body motion).

Migration speed and directionality switch of normal epithelial cells after TGF-β1-induced EMT (tEMT) on micro-structured polydimethylsiloxane (PDMS) substrates with variations in stiffness and topographic patterning.

PubMed

Wu, Tsung-Hsien; Li, Chia-Hui; Tang, Ming-Jer; Liang, Jen-I; Chen, Chia-Hsin; Yeh, Ming-Long

2013-10-01

The epithelial to mesenchymal transition (EMT) involves several physiological and pathological phenomena and endows cells with invasive and migratory properties. However, the effects of substrate stiffness and topography on the migration of cells before or after transforming growth factor-β1 (TGF-β1)-induced EMT (tEMT) are unknown. Herein, we seed control or tEMT NMuMG cells on the 2D patterns consisted of 1 μm or 5 μm line-widths and groove or cone patterns on either 2 MPa (1.96 ± 0.48 MPa) or 4 MPa (3.70 ± 0.74 MPa) polydimethylsiloxane (PDMS) substrates. After tEMT, the increased expression of α-SMA with vinculin in focal adhesion (FA) sites led to an acceleration of tEMT cell motility. On the 2 MPa substrate, the most influenced substrate was the 1 μm, cone-patterned substrate, where the tEMT cells' motility decelerated by 0.13 μm/min (36% slower than the cells on groove pattern). However, on the 5 μm, groove-patterned substrate, where the tEMT cells demonstrated the most rapid motility relative to the control cells, with an increment of 0.18 μm/min (100%). Among the different physical cues from substrate, the cone pattern could impede the migration speed of tEMT cells. Furthermore, we recommend the groove-patterned with a 5 μm line-width substrate as a useful tool to differentiate control and tEMT cells by migration speed.

The effect of law enforcement deployment patterns on motorists' speeds : final report.

DOT National Transportation Integrated Search

2003-12-01

The combination of increased demands on Oregons transportation system and limited law enforcement resources has led the Oregon Department of Transportation (ODOT) to investigate whether a relationship exists between motorists speeds and law enf...

Competitive interactions and resource partitioning between northern spotted owls and barred owls in western Oregon

USGS Publications Warehouse

Wiens, J. David; Anthony, Robert G.; Forsman, Eric D.

2014-01-01

The federally threatened northern spotted owl (Strix occidentalis caurina) is the focus of intensive conservation efforts that have led to much forested land being reserved as habitat for the owl and associated wildlife species throughout the Pacific Northwest of the United States. Recently, however, a relatively new threat to spotted owls has emerged in the form of an invasive competitor: the congeneric barred owl (S. varia). As barred owls have rapidly expanded their populations into the entire range of the northern spotted owl, mounting evidence indicates that they are displacing, hybridizing with, and even killing spotted owls. The range expansion by barred owls into western North America has made an already complex conservation issue even more contentious, and a lack of information on the ecological relationships between the 2 species has hampered recovery efforts for northern spotted owls. We investigated spatial relationships, habitat use, diets, survival, and reproduction of sympatric spotted owls and barred owls in western Oregon, USA, during 2007–2009. Our overall objective was to determine the potential for and possible consequences of competition for space, habitat, and food between these previously allopatric owl species. Our study included 29 spotted owls and 28 barred owls that were radio-marked in 36 neighboring territories and monitored over a 24-month period. Based on repeated surveys of both species, the number of territories occupied by pairs of barred owls in the 745-km2 study area (82) greatly outnumbered those occupied by pairs of spotted owls (15). Estimates of mean size of home ranges and core-use areas of spotted owls (1,843 ha and 305 ha, respectively) were 2–4 times larger than those of barred owls (581 ha and 188 ha, respectively). Individual spotted and barred owls in adjacent territories often had overlapping home ranges, but interspecific space sharing was largely restricted to broader foraging areas in the home range with minimal spatial overlap among core-use areas. We used an information-theoretic approach to rank discrete-choice models representing alternative hypotheses about the influence of forest conditions, topography, and interspecific interactions on species-specific patterns of nighttime resource selection. Spotted owls spent a disproportionate amount of time foraging on steep slopes in ravines dominated by old (>120 yr) conifer trees. Barred owls used available forest types more evenly than spotted owls, and were most strongly associated with patches of large hardwood and conifer trees that occupied relatively flat areas along streams. Spotted and barred owls differed in the relative use of old conifer forest (greater for spotted owls) and slope conditions (steeper slopes for spotted owls), but we found no evidence that the 2 species differed in their use of young, mature, and riparian-hardwood forest types. Mean overlap in proportional use of different forest types between individual spotted owls and barred owls in adjacent territories was 81% (range = 30–99%). The best model of habitat use for spotted owls indicated that the relative probability of a location being used was substantially reduced if the location was within or in close proximity to a core-use area of a barred owl. We used pellet analysis and measures of food-niche overlap to determine the potential for dietary competition between spatially associated pairs of spotted owls and barred owls. We identified 1,223 prey items from 15 territories occupied by spotted owls and 4,299 prey items from 24 territories occupied by barred owls. Diets of both species were dominated by nocturnal mammals, but diets of barred owls included many terrestrial, aquatic, and diurnal prey species that were rare or absent in diets of spotted owls. Northern flying squirrels (Glaucomys sabrinus), woodrats (Neotoma fuscipes, N. cinerea), and lagomorphs (Lepus americanus, Sylvilagus bachmani) were primary prey for both owl species, accounting for 81% and 49% of total dietary biomass for spotted owls and barred owls, respectively. Mean dietary overlap between pairs of spotted and barred owls in adjacent territories was moderate (42%; range = 28–70%). Barred owls displayed demographic superiority over spotted owls; annual survival probability of spotted owls from known-fate analyses (0.81, SE = 0.05) was lower than that of barred owls (0.92, SE = 0.04), and pairs of barred owls produced an average of 4.4 times more young than pairs of spotted owls over a 3-year period. We found a strong, positive relationship between seasonal (6-month) survival probabilities of both species and the proportion of old (>120 yr) conifer forest within individual home ranges, which suggested that availability of old forest was a potential limiting factor in the competitive relationship between these 2 species. The annual number of young produced by spotted owls increased linearly with increasing distance from a territory center of a pair of barred owls, and all spotted owls that attempted to nest within 1.5 km of a nest used by barred owls failed to successfully produce young. We identified strong associations between the presence of barred owls and the behavior and fitness potential of spotted owls, as shown by changes in movements, habitat use, and reproductive output of spotted owls exposed to different levels of spatial overlap with territorial barred owls. When viewed collectively, our results support the hypothesis that interference competition with barred owls for territorial space can constrain the availability of critical resources required for successful recruitment and reproduction of spotted owls. Availability of old forests and associated prey species appeared to be the most strongly limiting factors in the competitive relationship between these species, indicating that further loss of these conditions can lead to increases in competitive pressure. Our findings have broad implications for the conservation of spotted owls, as they suggest that spatial heterogeneity in vital rates may not arise solely because of differences among territories in the quality or abundance of forest habitat, but also because of the spatial distribution of a newly established competitor. Experimental removal of barred owls could be used to test this hypothesis and determine whether localized control of barred owl numbers is an ecologically practical and socio-politically acceptable management tool to consider in conservation strategies for spotted owls.

High-speed high-accuracy three-dimensional shape measurement using digital binary defocusing method versus sinusoidal method

NASA Astrophysics Data System (ADS)

Hyun, Jae-Sang; Li, Beiwen; Zhang, Song

2017-07-01

This paper presents our research findings on high-speed high-accuracy three-dimensional shape measurement using digital light processing (DLP) technologies. In particular, we compare two different sinusoidal fringe generation techniques using the DLP projection devices: direct projection of computer-generated 8-bit sinusoidal patterns (a.k.a., the sinusoidal method), and the creation of sinusoidal patterns by defocusing binary patterns (a.k.a., the binary defocusing method). This paper mainly examines their performance on high-accuracy measurement applications under precisely controlled settings. Two different projection systems were tested in this study: a commercially available inexpensive projector and the DLP development kit. Experimental results demonstrated that the binary defocusing method always outperforms the sinusoidal method if a sufficient number of phase-shifted fringe patterns can be used.

High-speed 3D imaging using digital binary defocusing method vs sinusoidal method

NASA Astrophysics Data System (ADS)

Zhang, Song; Hyun, Jae-Sang; Li, Beiwen

2017-02-01

This paper presents our research findings on high-speed 3D imaging using digital light processing (DLP) technologies. In particular, we compare two different sinusoidal fringe generation techniques using the DLP projection devices: direct projection of 8-bit computer generated sinusoidal patterns (a.k.a, the sinusoidal method), and the creation of sinusoidal patterns by defocusing binary patterns (a.k.a., the binary defocusing method). This paper mainly examines their performance on high-accuracy measurement applications under precisely controlled settings. Two different projection systems were tested in this study: the commercially available inexpensive projector, and the DLP development kit. Experimental results demonstrated that the binary defocusing method always outperforms the sinusoidal method if a sufficient number of phase-shifted fringe patterns can be used.

A Quadruped Robot Exhibiting Spontaneous Gait Transitions from Walking to Trotting to Galloping.

PubMed

Owaki, Dai; Ishiguro, Akio

2017-03-21

The manner in which quadrupeds change their locomotive patterns-walking, trotting, and galloping-with changing speed is poorly understood. In this paper, we provide evidence for interlimb coordination during gait transitions using a quadruped robot for which coordination between the legs can be self-organized through a simple "central pattern generator" (CPG) model. We demonstrate spontaneous gait transitions between energy-efficient patterns by changing only the parameter related to speed. Interlimb coordination was achieved with the use of local load sensing only without any preprogrammed patterns. Our model exploits physical communication through the body, suggesting that knowledge of physical communication is required to understand the leg coordination mechanism in legged animals and to establish design principles for legged robots that can reproduce flexible and efficient locomotion.

Scalable maskless patterning of nanostructures using high-speed scanning probe arrays

NASA Astrophysics Data System (ADS)

Chen, Chen; Akella, Meghana; Du, Zhidong; Pan, Liang

2017-08-01

Nanoscale patterning is the key process to manufacture important products such as semiconductor microprocessors and data storage devices. Many studies have shown that it has the potential to revolutionize the functions of a broad range of products for a wide variety of applications in energy, healthcare, civil, defense and security. However, tools for mass production of these devices usually cost tens of million dollars each and are only affordable to the established semiconductor industry. A new method, nominally known as "pattern-on-the- y", that involves scanning an array of optical or electrical probes at high speed to form nanostructures and offers a new low-cost approach for nanoscale additive patterning. In this paper, we report some progress on using this method to pattern self-assembled monolayers (SAMs) on silicon substrate. We also functionalize the substrate with gold nanoparticle based on the SAM to show the feasibility of preparing amphiphilic and multi-functional surfaces.

Is the rearfoot pattern the most frequently foot strike pattern among recreational shod distance runners?

PubMed

de Almeida, Matheus Oliveira; Saragiotto, Bruno Tirotti; Yamato, Tiê Parma; Lopes, Alexandre Dias

2015-02-01

To determine the distribution of the foot strike patterns among recreational shod runners and to compare the personal and training characteristics between runners with different foot strike patterns. Cross-sectional study. Areas of running practice in São Paulo, Brazil. 514 recreational shod runners older than 18 years and free of injury. Foot strike patterns were evaluated with a high-speed camera (250 Hz) and photocells to assess the running speed of participants. Personal and training characteristics were collected through a questionnaire. The inter-rater reliability of the visual foot strike pattern classification method was 96.7% and intra-rater reliability was 98.9%. 95.1% (n = 489) of the participants were rearfoot strikers, 4.1% (n = 21) were midfoot strikers, and four runners (0.8%) were forefoot strikers. There were no significant differences between strike patterns for personal and training characteristics. This is the first study to demonstrate that almost all recreational shod runners were rearfoot strikers. The visual method of evaluation seems to be a reliable and feasible option to classify foot strike pattern. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pattern dependence in high-speed Q-modulated distributed feedback laser.

PubMed

Zhu, Hongli; Xia, Yimin; He, Jian-Jun

2015-05-04

We investigate the pattern dependence in high speed Q-modulated distributed feedback laser based on its complete physical structure and material properties. The structure parameters of the gain section as well as the modulation and phase sections are all taken into account in the simulations based on an integrated traveling wave model. Using this model, we show that an example Q-modulated DFB laser can achieve an extinction ratio of 6.8dB with a jitter of 4.7ps and a peak intensity fluctuation of less than 15% for 40Gbps RZ modulation signal. The simulation method is proved very useful for the complex laser structure design and high speed performance optimization, as well as for providing physical insight of the operation mechanism.

A comparative study of Cr-X-N (X=Zr, Si) coatings for the improvement of the low-speed torque efficiency of a hydraulic piston pump

NASA Astrophysics Data System (ADS)

Hong, Yeh-Sun; Lee, Sang-Yul

2008-02-01

The internal parts of hydraulic pumps operating at variable speed should be protected from insufficient lubrication. The axial piston type pumps employ a steel-base cylinder barrel rotating on a soft bronze valves plate with a slide contact, where the insufficient lubrication of these components can cause rapid wear of the valve plate and increase the friction loss. In this study, the cylinder barrel surface was deposited with CrZrN coatings, which were expected to improve the tribological contact with a valve plate under low-speed mixed lubrication conditions. Its effect on the improvement of the low-speed torque efficiency of a hydraulic piston pump was investigated and compared with that from the CrSiN coating. The coated cylinder barrels showed much lower friction coefficients and wear rates of the valve plates than the uncoated plasma-nitride one. In particular, the CrZrN coatings revealed better performance than the CrSiN coatings. By representing the improvement in the torque efficiency of the whole pump based upon the degree of the friction coefficient reduction, the CrZrN coatings exhibited approximately a 0.35% higher improvement at 300 bar and 100 rpm than CrSiN coatings. The possible failure modes of the coatings coated on the barrel were sugested and the microstructures of the coatings seemed to have a strong effect on the film failure mode.

Writing forces associated with four pencil grasp patterns in grade 4 children.

PubMed

Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl; Chau, Tom

2013-01-01

OBJECTIVE. We investigated differences in handwriting kinetics, speed, and legibility among four pencil grasps after a 10-min copy task. METHOD. Seventy-four Grade 4 students completed a handwriting assessment before and after a copy task. Grip and axial forces were measured with an instrumented stylus and force-sensitive tablet. We used multiple linear regression to analyze the relationship between grasp pattern and grip and axial forces. RESULTS. We found no kinetic differences among grasps, whether considered individually or grouped by the number of fingers on the barrel. However, when grasps were grouped according to the thumb position, the adducted grasps exhibited higher mean grip and axial forces. CONCLUSION. Grip forces were generally similar across the different grasps. Kinetic differences resulting from thumb position seemed to have no bearing on speed and legibility. Interventions for handwriting difficulties should focus more on speed and letter formation than on grasp pattern. Copyright © 2013 by the American Occupational Therapy Association, Inc.

Topographic and hydraulic controls over alluviation on a bedrock template

NASA Astrophysics Data System (ADS)

Milan, David; Heritage, George; Entwistle, Neil; Tooth, Stephen

2017-04-01

Bedrock-alluvial anastomosed channels found in dryland rivers are characterised by an over-wide channel cut into the host rock containing a network of interconnecting bedrock sub-channels separated by bedrock influenced interfluve areas. Whilst the channels remain largely free of sediment the interfluves display varying levels of alluviation ranging from bare rock, sand sheets and silt drapes through to consolidated bedrock core bars, islands and lateral deposits. Examination of the sedimentary units associated with the bedrock anastomosed reaches of the Sabie river in the Kruger National Park, South Africa reveal a repeating sequence of coarse sand / fine gravel grading through to silt representing successive flood related depositional units. Unit development in relation to the bedrock template was investigated using pre-flood aerial imagery of bedrock core bar locations and post flood LiDAR data of bedrock anastomosed sites stripped during the 2000 and 2012 extreme flood events. This revealed a propensity for bar development associated with bedrock hollows disconnected from the principal high-energy sub-channels. 2-D morpho-dynamic modelling was used to further investigate spatial patterns of deposition over the bedrock template. Although topographic lows displayed mid-range velocities during peak flow events, these are likely to be preferential routing areas, with sediments stalling in low energy areas on the falling limb of floods. It is also likely that vegetation development plays a fundamental role in the development of alluviated zones, through increasing strength of alluvial units and capturing new sediments. With these results in mind we present a conceptual model for the development of bedrock-core bars, the fundamental unit in bedrock-alluvial anastomosed channels.

Transition of torque pattern in undulatory locomotion due to wave number variation in resistive force dominated media

NASA Astrophysics Data System (ADS)

Ding, Yang; Ming, Tingyu

2016-11-01

In undulatory locomotion, torque (bending moment) is required along the body to overcome the external forces from environments and bend the body. Previous observations on animals using less than two wavelengths on the body showed such torque has a single traveling wave pattern. Using resistive force theory model and considering the torque generated by external force in a resistive force dominated media, we found that as the wave number (number of wavelengths on the locomotor's body) increases from 0.5 to 1.8, the speed of the traveling wave of torque decreases. When the wave number increases to 2 and greater, the torque pattern transits from a single traveling wave to a two traveling waves and then a complex pattern that consists two wave-like patterns. By analyzing the force distribution and its contribution to the torque, we explain the speed decrease of the torque wave and the pattern transition. This research is partially supported by the Recruitment Program of Global Young Experts (China).

Omission P3 after voluntary action indexes the formation of action-driven prediction.

PubMed

Kimura, Motohiro; Takeda, Yuji

2018-02-01

When humans frequently experience a certain sensory effect after a certain action, a bidirectional association between neural representations of the action and the sensory effect is rapidly acquired, which enables action-driven prediction of the sensory effect. The present study aimed to test whether or not omission P3, an event-related brain potential (ERP) elicited by the sudden omission of a sensory effect, is sensitive to the formation of action-driven prediction. For this purpose, we examined how omission P3 is affected by the number of possible visual effects. In four separate blocks (1-, 2-, 4-, and 8-stimulus blocks), participants successively pressed a right button at an interval of about 1s. In all blocks, each button press triggered a bar on a display (a bar with square edges, 85%; a bar with round edges, 5%), but occasionally did not (sudden omission of a visual effect, 10%). Participants were required to press a left button when a bar with round edges appeared. In the 1-stimulus block, the orientation of the bar was fixed throughout the block; in the 2-, 4-, and 8-stimulus blocks, the orientation was randomly varied among two, four, and eight possibilities, respectively. Omission P3 in the 1-stimulus block was greater than those in the 2-, 4-, and 8-stimulus blocks; there were no significant differences among the 2-, 4-, and 8-stimulus blocks. This binary pattern nicely fits the limitation in the acquisition of action-effect association; although an association between an action and one visual effect is easily acquired, associations between an action and two or more visual effects cannot be acquired concurrently. Taken together, the present results suggest that omission P3 is highly sensitive to the formation of action-driven prediction. Copyright © 2017 Elsevier B.V. All rights reserved.

Reliability and Validity of Digital Imagery Methodology for Measuring Starting Portions and Plate Waste from School Salad Bars.

PubMed

Bean, Melanie K; Raynor, Hollie A; Thornton, Laura M; Sova, Alexandra; Dunne Stewart, Mary; Mazzeo, Suzanne E

2018-04-12

Scientifically sound methods for investigating dietary consumption patterns from self-serve salad bars are needed to inform school policies and programs. To examine the reliability and validity of digital imagery for determining starting portions and plate waste of self-serve salad bar vegetables (which have variable starting portions) compared with manual weights. In a laboratory setting, 30 mock salads with 73 vegetables were made, and consumption was simulated. Each component (initial and removed portion) was weighed; photographs of weighed reference portions and pre- and post-consumption mock salads were taken. Seven trained independent raters visually assessed images to estimate starting portions to the nearest ¼ cup and percentage consumed in 20% increments. These values were converted to grams for comparison with weighed values. Intraclass correlations between weighed and digital imagery-assessed portions and plate waste were used to assess interrater reliability and validity. Pearson's correlations between weights and digital imagery assessments were also examined. Paired samples t tests were used to evaluate mean differences (in grams) between digital imagery-assessed portions and measured weights. Interrater reliabilities were excellent for starting portions and plate waste with digital imagery. For accuracy, intraclass correlations were moderate, with lower accuracy for determining starting portions of leafy greens compared with other vegetables. However, accuracy of digital imagery-assessed plate waste was excellent. Digital imagery assessments were not significantly different from measured weights for estimating overall vegetable starting portions or waste; however, digital imagery assessments slightly underestimated starting portions (by 3.5 g) and waste (by 2.1 g) of leafy greens. This investigation provides preliminary support for use of digital imagery in estimating starting portions and plate waste from school salad bars. Results might inform methods used in empirical investigations of dietary intake in schools with self-serve salad bars. Copyright © 2018 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Cross-border policy effects on alcohol outcomes: drinking without thinking on the u.s.-Mexico border?

PubMed

Mills, Britain A; Caetano, Raul; Vaeth, Patrice

2014-11-01

Rates of alcohol-related outcomes are sensitive to policy differences in politically distinct, adjacent territories. Factors that shape these cross-border effects, particularly when the policy differences are longstanding, remain poorly understood. We compared the ability of 2 classes of variables with theoretical relevance to the U.S.-Mexico border context-bar attendance and alcohol-related social-cognitive variables-to explain elevated drinking on the U.S. side of the border relative to other areas of the United States. Data were collected from multistage cluster samples of adult Mexican Americans on and off the U.S.-Mexico border (current drinker N = 1,351). Structural equation models were used to test drinking context (frequency of bar attendance) and 6 different social-cognitive variables (including alcohol-related attitudes, norms, motives, and beliefs) as mediators of border effects on a composite drinking index. The border effect on drinking varied by age (with younger adults showing a stronger effect), consistent with previous findings and known risk factors in the region. Contrary to theoretical expectations, 6 different social-cognitive variables-despite relating strongly with drinking-were comparable in border and nonborder areas (within and across age) and played no role in elevated drinking on the border. Conversely, elevated drinking among border youth was mediated by bar attendance. This mediated moderation effect held after adjusting for potential sociodemographic and neighborhood-level confounders. Increased drinking among U.S.-Mexico border youth is explained by patterns of bar attendance, but not by more permissive alcohol-related social-cognitive variables in border areas: Border youth attend bars and drink more than their nonborder counterparts, despite having comparable alcohol-related beliefs, attitudes, norms, and motives for use. Alcohol's heightened availability and visibility on both sides of the border may create opportunities for border youth to drink that otherwise would not be considered. Copyright © 2014 by the Research Society on Alcoholism.

[Spanish drivers' beliefs about speed. Speeding is a major issue of road safety].

PubMed

Montoro González, Luis; Roca Ruiz, Javier; Lucas-Alba, Antonio

2010-11-01

Extending and updating our knowledge concerning drivers' motivational and cognitive processes is of essential importance if we are to apply policies with long-lasting effects. This study presents data from a representative national survey analyzing the Spanish drivers' beliefs about speed, the risks of speeding, the degree of violation of speed-limits and the reasons for speeding. Results indicate that Spanish drivers rate speeding as a serious offence, yet not among the most dangerous ones. All in all, they claim to comply mostly with the speed limits. However, some interesting violation patterns emerge: observance is lower for generic speed limits according to road type (vs. specific limits shown by certain road signs), and particularly in motorways (vs. single carriageways and urban areas). Risk perception and reasons for speeding emerge as the main factors predicting the levels of speed violations reported. Results suggest that any effective intervention strategy should consider such factors, namely the link between speed, road safety, and drivers' specific reasons for speeding.

Pressurized security barrier and alarm system

DOEpatents

Carver, Don W.

1995-01-01

A security barrier for placement across a passageway is made up of interconnected pressurized tubing made up in a grid pattern with openings too small to allow passage. The tubing is connected to a pressure switch, located away from the barrier site, which activates an alarm upon occurrence of a pressure drop. A reinforcing bar is located inside and along the length of the tubing so as to cause the tubing to rupture and set off the alarm upon an intruder's making an attempt to crimp and seal off a portion of the tubing by application of a hydraulic tool. Radial and rectangular grid patterns are disclosed.

Pressurized security barrier and alarm system

DOEpatents

Carver, D.W.

1995-04-11

A security barrier for placement across a passageway is made up of interconnected pressurized tubing made up in a grid pattern with openings too small to allow passage. The tubing is connected to a pressure switch, located away from the barrier site, which activates an alarm upon occurrence of a pressure drop. A reinforcing bar is located inside and along the length of the tubing so as to cause the tubing to rupture and set off the alarm upon an intruder`s making an attempt to crimp and seal off a portion of the tubing by application of a hydraulic tool. Radial and rectangular grid patterns are disclosed. 7 figures.

STAR CLUSTERS IN A NUCLEAR STAR FORMING RING: THE DISAPPEARING STRING OF PEARLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Väisänen, Petri; Barway, Sudhanshu; Randriamanakoto, Zara, E-mail: petri@saao.ac.za

2014-12-20

An analysis of the star cluster population in a low-luminosity early-type galaxy, NGC 2328, is presented. The clusters are found in a tight star forming nuclear spiral/ring pattern and we also identify a bar from structural two-dimensional decomposition. These massive clusters are forming very efficiently in the circumnuclear environment and they are young, possibly all less than 30 Myr of age. The clusters indicate an azimuthal age gradient, consistent with a ''pearls-on-a-string'' formation scenario, suggesting bar-driven gas inflow. The cluster mass function has a robust down turn at low masses at all age bins. Assuming clusters are born with a power-lawmore » distribution, this indicates extremely rapid disruption at timescales of just several million years. If found to be typical, it means that clusters born in dense circumnuclear rings do not survive to become old globular clusters in non-interacting systems.« less

Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California

Treesearch

John D. Alexander; Nathaniel E. Seavy; C Ralph; Bill Hogoboom

2006-01-01

We used vegetation data collected in areas before they were burned by the 2500 ha Quartz fire in southern Oregon and the 50 600 ha Big Bar complex in northern California to evaluate the ability of vegetation and topographic characteristics to predict patterns of fire severity. Fire severity was characterized as high, moderate, or low based on crown scorch and...

A model for diurnal patterns of carbon fixation in a Precambrian microbial mat based on a modern analog

NASA Technical Reports Server (NTRS)

Rothschild, L. J.

1991-01-01

Microbial mat communities are one of the first and most prevalent biological communities known from the Precambrian fossil record. These fossil mat communities are found as laminated sedimentary rock structures called stromatolites. Using a modern microbial mat as an analog for Precambrian stromatolites, a study of carbon fixation during a diurnal cycle under ambient conditions was undertaken. The rate of carbon fixation depends primarily on the availability of light (consistent with photosynthetic carbon fixation) and inorganic carbon, and not nitrogen or phosphorus. Atmospheric PCO2 is thought to have decreased from 10 bars at 4 Ga (10(9) years before present) to approximately 10(-4) bars today, implying a change in the availability of inorganic carbon for carbon fixation. Experimental manipulation of levels of inorganic carbon to levels that may have been available to Precambrian mat communities resulted in increased levels of carbon fixation during daylight hours. Combining these data with models of daylength during the Precambrian, models are derived for diurnal patterns of photosynthetic carbon fixation in a Precambrian microbial mat community. The models suggest that, even in the face of shorter daylengths during the Precambrian, total daily carbon fixation has been declining over geological time, with most of the decrease having occurred during the Precambrian.

Implications of the Daya Bay observation of θ13 on the leptonic flavor mixing structure and CP violation

NASA Astrophysics Data System (ADS)

Xing, Zhi-Zhong

2012-04-01

The Daya Bay collaboration has recently reported its first bar nue → bar nue oscillation result which points to θ13 simeq 8.8° +/- 0.8° (best-fit +/-1σ range) or θ13 ≠ 0° at the 5.2σ level. The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and CP violation. Two phenomenological strategies are outlined: (1) the lepton flavor mixing matrix U consists of a constant leading term U0 and a small perturbation term ΔU and (2) the mixing angles of U are associated with the lepton mass ratios. Some typical patterns of U0 are reexamined by constraining their respective perturbations with current experimental data. We illustrate a few possible ways to minimally correct U0 in order to fit the observed values of three mixing angles. We point out that the structure of U may exhibit an approximate μ-τ permutation symmetry in modulus, and reiterate the geometrical description of CP violation in terms of the leptonic unitarity triangles. The salient features of nine distinct parametrizations of U are summarized, and its Wolfenstein-like expansion is presented by taking U0 to be the democratic mixing pattern.

Application of magnetoelastic materials in spatiotemporally modulated phononic crystals for nonreciprocal wave propagation

NASA Astrophysics Data System (ADS)

Ansari, M. H.; Attarzadeh, M. A.; Nouh, M.; Karami, M. Amin

2018-01-01

In this paper, a physical platform is proposed to change the properties of phononic crystals in space and time in order to achieve nonreciprocal wave transmission. The utilization of magnetoelastic materials in elastic phononic systems is studied. Material properties of magnetoelastic materials change significantly with an external magnetic field. This property is used to design systems with a desired wave propagation pattern. The properties of the magnetoelastic medium are changed in a traveling wave pattern, which changes in both space and time. A phononic crystal with such a modulation exhibits one-way wave propagation behavior. An extended transfer matrix method (TMM) is developed to model a system with time varying properties. The stop band and the pass band of a reciprocal and a nonreciprocal bar are found using this method. The TMM is used to find the transfer function of a magnetoelastic bar. The obtained results match those obtained via the theoretical Floquet-Bloch approach and numerical simulations. It is shown that the stop band in the transfer function of a system with temporal varying property for the forward wave propagation is different from the same in the backward wave propagation. The proposed configuration enables the physical realization of a class of smart structures that incorporates nonreciprocal wave propagation.

The significance of sediment transport in arroyo development

USGS Publications Warehouse

Meyer, David F.

1989-01-01

Arroyo widening dominates postincisional arroyo development, and the manner of widening is dependent on the grain size of bed material transported by the channel. When bed material is predominantly gravel, subaqueous bars that alternate from one side of the channel to the other form during high flows in initially narrow, often straight, arroyos. These alternate bars grow and become coarse-grained point bars. Moderate and low flows cannot rework these coarse bars, and the channel meanders around them. Arroyo walls opposite the bars are undercut and eroded. With progressive arroyo widening by erosion of cut banks, high-flow channel width increases, and depth decreases, reducing channel competence. Gravel is deposited in midchannel bars, point bars are reworked, and the channel becomes braided. As braiding becomes dominant, both arroyo walls are eroded. This conceptual model of coarse-grained arroyo development is based on observations of arroyo development through time using physical models and interpretation of the channel and arroyo morphology and sedimentology during a short period along the San Simon, San Pedro, and Santa Cruz Rivers in southeast Arizona. When bed material is predominantly sand, the channel pattern within initial arroyos is typically braided, and both arroyo walls are actively eroded. Alternate bars may form within single-thread, high-flow channels, but they are reworked during recessional flows, and the .low-flow channel is again braided. With progressive arroyo widening, fine sand, silt, and clay carried in suspension are deposited across a flood plain within the wide arroyo, causing the channel to meander. This fine-grained arroyo development model is based on observations of arroyo development through time using physical models and interpretation of the channel and arroyo morphology and sedimentology during a short period along the Rio Puerco, New Mexico. Experimental investigations using physical models in which incised channels were monitored through time indicate that the rate of arroyo widening is dependent on the amount of bedload transported through a reach. This is documented by the relations between the rate of arroyo erosion and the observed sediment transport, the channel slope, the channel width and the channel width-to-depth ratio. When a small amount of bed material is being transported, arroyos do not widen whether they are narrow (arroyo width-to-depth ratios between 1.5 and 3.1), intermediate (between 2.5 and 4.8), or wide (greater than 4.9). Arroyo widening resumes when a larger supply of bed material is introduced. Arroyo widening decreases through time because with progressive increases of arroyo width, the frequency with which unstable channels within the arroyo impinge upon arroyo walls decreases. Arroyos become wider in a downstream direction in response to the cumulative effect of upstream sediment production.

Optimization and Analysis of Laser Beam Machining Parameters for Al7075-TiB2 In-situ Composite

NASA Astrophysics Data System (ADS)

Manjoth, S.; Keshavamurthy, R.; Pradeep Kumar, G. S.

2016-09-01

The paper focuses on laser beam machining (LBM) of In-situ synthesized Al7075-TiB2 metal matrix composite. Optimization and influence of laser machining process parameters on surface roughness, volumetric material removal rate (VMRR) and dimensional accuracy of composites were studied. Al7075-TiB2 metal matrix composite was synthesized by in-situ reaction technique using stir casting process. Taguchi's L9 orthogonal array was used to design experimental trials. Standoff distance (SOD) (0.3 - 0.5mm), Cutting Speed (1000 - 1200 m/hr) and Gas pressure (0.5 - 0.7 bar) were considered as variable input parameters at three different levels, while power and nozzle diameter were maintained constant with air as assisting gas. Optimized process parameters for surface roughness, volumetric material removal rate (VMRR) and dimensional accuracy were calculated by generating the main effects plot for signal noise ratio (S/N ratio) for surface roughness, VMRR and dimensional error using Minitab software (version 16). The Significant of standoff distance (SOD), cutting speed and gas pressure on surface roughness, volumetric material removal rate (VMRR) and dimensional error were calculated using analysis of variance (ANOVA) method. Results indicate that, for surface roughness, cutting speed (56.38%) is most significant parameter followed by standoff distance (41.03%) and gas pressure (2.6%). For volumetric material removal (VMRR), gas pressure (42.32%) is most significant parameter followed by cutting speed (33.60%) and standoff distance (24.06%). For dimensional error, Standoff distance (53.34%) is most significant parameter followed by cutting speed (34.12%) and gas pressure (12.53%). Further, verification experiments were carried out to confirm performance of optimized process parameters.

Symmetric Absorber-Coupled Far-Infrared Microwave Kinetic Inductance Detector

NASA Technical Reports Server (NTRS)

U-yen, Kongpop (Inventor); Wollack, Edward J. (Inventor); Brown, Ari D. (Inventor); Stevenson, Thomas R. (Inventor); Patel, Amil A. (Inventor)

2016-01-01

The present invention relates to a symmetric absorber-coupled far-infrared microwave kinetic inductance detector including: a membrane having an absorber disposed thereon in a symmetric cross bar pattern; and a microstrip including a plurality of conductor microstrip lines disposed along all edges of the membrane, and separated from a ground plane by the membrane. The conducting microstrip lines are made from niobium, and the pattern is made from a superconducting material with a transition temperature below niobium, including one of aluminum, titanium nitride, or molybdenum nitride. The pattern is disposed on both a top and a bottom of the membrane, and creates a parallel-plate coupled transmission line on the membrane that acts as a half-wavelength resonator at readout frequencies. The parallel-plate coupled transmission line and the conductor microstrip lines form a stepped impedance resonator. The pattern provides identical power absorption for both horizontal and vertical polarization signals.

Effects of gyrokinesis exercise on the gait pattern of female patients with chronic low back pain

PubMed Central

Seo, Kook-Eun; Park, Tae-Jin

2016-01-01

[Purpose] The purpose of the present study was to use kinematic variables to identify the effects of 8/weeks’ performance of a gyrokinesis exercise on the gait pattern of females with chronic low back pain. [Subjects] The subjects of the present study were females in their late 20s to mid 30s who were chronic back pain patients. [Methods] A 3-D motion analysis system was used to measure the changes in their gait patterns between pre and post-gyrokintic exercise. The SPSS 21.0 statistics program was used to perform the paired t-test, to compare the gait patterns of pre-post-gyrokinesis exercise. [Results] In the gait analysis, pre-post-gyrokinesis exercise gait patterns showed statistically significant differences in right and left step length, stride length, right-left step widths, and stride speed. [Conclusion] Gait pattern analysis revealed increases in step length, stride length, and stride speed along with a decrease in step width after 8 weeks of gyrokinesis exercise, demonstrating it improved gait pattern. PMID:27065537

Quantum Associative Neural Network with Nonlinear Search Algorithm

NASA Astrophysics Data System (ADS)

Zhou, Rigui; Wang, Huian; Wu, Qian; Shi, Yang

2012-03-01

Based on analysis on properties of quantum linear superposition, to overcome the complexity of existing quantum associative memory which was proposed by Ventura, a new storage method for multiply patterns is proposed in this paper by constructing the quantum array with the binary decision diagrams. Also, the adoption of the nonlinear search algorithm increases the pattern recalling speed of this model which has multiply patterns to O( {log2}^{2^{n -t}} ) = O( n - t ) time complexity, where n is the number of quantum bit and t is the quantum information of the t quantum bit. Results of case analysis show that the associative neural network model proposed in this paper based on quantum learning is much better and optimized than other researchers' counterparts both in terms of avoiding the additional qubits or extraordinary initial operators, storing pattern and improving the recalling speed.

Numerical Simulation of the Global Star Formation Pattern in the LMC

NASA Astrophysics Data System (ADS)

Gardiner, L. T.; Turfus, C.

Dottori et al. (1996, ApJ 461, 742) have recently presented evidence for the idea that the observed distribution of young star clusters in the Large Magellanic Cloud (LMC) has resulted from the gravitational perturbation induced by a bar potential offset from the LMC disk center. We have constructed a dynamical model of the LMC to examine the effects of such an off-center perturbation on the global distribution of the gas and star formation activity. We have used a newly developed hybrid N-body/cellular automaton scheme for modeling star formation in galaxies which incorporates the dual mechanisms of gravitational instability and self-propagating star formation, combined with feedback of kinetic energy from star-forming regions into the interstellar medium. We find that a weak rotating bar perturbation, whose center is displaced by 0.6 kpc from the disk center, gives rise to an asymmetric spiral structure which mimics the chains of recent star formation observed in the LMC as well as delineating activity in the bar region. Large gas concentrations are produced where the spiral arms merge in the northern part of the galaxy, and such structures may have observed counterparts in giant star-forming complexes such as Constellation III in the NE part of the LMC.

Hedgehog signaling mediates adaptive variation in a dynamic functional system in the cichlid feeding apparatus.

PubMed

Hu, Yinan; Albertson, R Craig

2014-06-10

Adaptive variation in the craniofacial skeleton is a key component of resource specialization and habitat divergence in vertebrates, but the proximate genetic mechanisms that underlie complex patterns of craniofacial variation are largely unknown. Here we demonstrate that the Hedgehog (Hh) signaling pathway mediates widespread variation across a complex functional system that affects the kinematics of lower jaw depression--the opercular four-bar linkage apparatus--among Lake Malawi cichlids. By using a combined quantitative trait locus mapping and population genetics approach, we show that allelic variation in the Hh receptor, ptch1, affects the development of distinct bony elements in the head that represent two of three movable links in this functional system. The evolutionarily derived allele is found in species that feed from the water column, and is associated with shifts in anatomy that translate to a four-bar system capable of faster jaw rotation. Alternatively, the ancestral allele is found in species that feed on attached algae, and is associated with the development of a four-bar system that predicts slower jaw movement. Experimental manipulation of the Hh pathway during cichlid development recapitulates functionally salient natural variation in craniofacial geometry. In all, these results significantly extend our understanding of the mechanisms that fine-tune the craniofacial skeletal complex during adaptation to new foraging niches.

Impact of the Lok-bar for High-precision Radiotherapy with Tomotherapy.

PubMed

Hirata, Makoto; Monzen, Hajime; Tamura, Mikoto; Kubo, Kazuki; Matsumoto, Kenji; Hanaoka, Kohei; Okumura, Masahiko; Nishimura, Yasumasa

2018-05-01

Patient immobilization systems are used to establish a reproducible patient position relative to the couch. In this study, the impact of conventional lok-bars for CT-simulation (CIVCO-bar) and treatment (iBEAM-bar) were compared with a novel lok-bar (mHM-bar) in tomotherapy. Verification was obtained as follows: i. artifacts in CT images; ii. dose attenuation rate of lok-bar, compared to without lok-bar; and iii. dose differences between the calculated and measured absorbed doses. With the CIVCO-bar, there were obvious metal artifacts, while there were nearly no artifacts with the mHM-bar. The mean dose attenuation rates with the mHM-bar and iBEAM-bar were 1.31% and 2.28%, and the mean dose difference was 1.55% and 1.66% for mHM-bar and iBEAM-bar. Using the mHM-bar reduced artifacts on the CT image and improved dose attenuation are obtained. The lok-bar needs to be inserted as a structure set in treatment planning with tomotherapy. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Association between stride time fractality and gait adaptability during unperturbed and asymmetric walking.

PubMed

Ducharme, Scott W; Liddy, Joshua J; Haddad, Jeffrey M; Busa, Michael A; Claxton, Laura J; van Emmerik, Richard E A

2018-04-01

Human locomotion is an inherently complex activity that requires the coordination and control of neurophysiological and biomechanical degrees of freedom across various spatiotemporal scales. Locomotor patterns must constantly be altered in the face of changing environmental or task demands, such as heterogeneous terrains or obstacles. Variability in stride times occurring at short time scales (e.g., 5-10 strides) is statistically correlated to larger fluctuations occurring over longer time scales (e.g., 50-100 strides). This relationship, known as fractal dynamics, is thought to represent the adaptive capacity of the locomotor system. However, this has not been tested empirically. Thus, the purpose of this study was to determine if stride time fractality during steady state walking associated with the ability of individuals to adapt their gait patterns when locomotor speed and symmetry are altered. Fifteen healthy adults walked on a split-belt treadmill at preferred speed, half of preferred speed, and with one leg at preferred speed and the other at half speed (2:1 ratio asymmetric walking). The asymmetric belt speed condition induced gait asymmetries that required adaptation of locomotor patterns. The slow speed manipulation was chosen in order to determine the impact of gait speed on stride time fractal dynamics. Detrended fluctuation analysis was used to quantify the correlation structure, i.e., fractality, of stride times. Cross-correlation analysis was used to measure the deviation from intended anti-phasing between legs as a measure of gait adaptation. Results revealed no association between unperturbed walking fractal dynamics and gait adaptability performance. However, there was a quadratic relationship between perturbed, asymmetric walking fractal dynamics and adaptive performance during split-belt walking, whereby individuals who exhibited fractal scaling exponents that deviated from 1/f performed the poorest. Compared to steady state preferred walking speed, fractal dynamics increased closer to 1/f when participants were exposed to asymmetric walking. These findings suggest there may not be a relationship between unperturbed preferred or slow speed walking fractal dynamics and gait adaptability. However, the emergent relationship between asymmetric walking fractal dynamics and limb phase adaptation may represent a functional reorganization of the locomotor system (i.e., improved interactivity between degrees of freedom within the system) to be better suited to attenuate externally generated perturbations at various spatiotemporal scales. Copyright © 2018 Elsevier B.V. All rights reserved.

The Effect of Differences in Day and Night Lighting Distributions on Drivers' Speed Perception.

PubMed

Kim, Jonathan D; Perrone, John A; Isler, Robert B

2017-06-01

Previous research has shown that changes to contrast levels in the visual environment caused by fog can affect drivers' perceptions of speed. It is not easy, however, to extrapolate these results to other driving scenarios in which contrast is affected, such as during nighttime driving, because the measure of contrast is more complex when considering factors such as the illumination provided by headlights. Therefore, we investigated the differences in lighting distribution patterns between day- and nighttime driving on speed perception using prerendered 3D scenarios representing driving on a rural road. A two-alternative forced-choice design based on the method of constant stimuli was utilised, with 32 participants viewing a series of pairs of scenarios (day vs. night driving) from a driver's perspective while indicating for each pair whether the second scenario was faster or slower than the first scenario. Our results indicated that speed discrimination accuracy was minimally affected by changes in lighting distribution patterns between day and night.

Activating and Relaxing Music Entrains the Speed of Beat Synchronized Walking

PubMed Central

Leman, Marc; Moelants, Dirk; Varewyck, Matthias; Styns, Frederik; van Noorden, Leon; Martens, Jean-Pierre

2013-01-01

Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is ‘activating’ in the sense that it increases the speed, and some music is ‘relaxing’ in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation. PMID:23874469

Activating and relaxing music entrains the speed of beat synchronized walking.

PubMed

Leman, Marc; Moelants, Dirk; Varewyck, Matthias; Styns, Frederik; van Noorden, Leon; Martens, Jean-Pierre

2013-01-01

Inspired by a theory of embodied music cognition, we investigate whether music can entrain the speed of beat synchronized walking. If human walking is in synchrony with the beat and all musical stimuli have the same duration and the same tempo, then differences in walking speed can only be the result of music-induced differences in stride length, thus reflecting the vigor or physical strength of the movement. Participants walked in an open field in synchrony with the beat of 52 different musical stimuli all having a tempo of 130 beats per minute and a meter of 4 beats. The walking speed was measured as the walked distance during a time interval of 30 seconds. The results reveal that some music is 'activating' in the sense that it increases the speed, and some music is 'relaxing' in the sense that it decreases the speed, compared to the spontaneous walked speed in response to metronome stimuli. Participants are consistent in their observation of qualitative differences between the relaxing and activating musical stimuli. Using regression analysis, it was possible to set up a predictive model using only four sonic features that explain 60% of the variance. The sonic features capture variation in loudness and pitch patterns at periods of three, four and six beats, suggesting that expressive patterns in music are responsible for the effect. The mechanism may be attributed to an attentional shift, a subliminal audio-motor entrainment mechanism, or an arousal effect, but further study is needed to figure this out. Overall, the study supports the hypothesis that recurrent patterns of fluctuation affecting the binary meter strength of the music may entrain the vigor of the movement. The study opens up new perspectives for understanding the relationship between entrainment and expressiveness, with the possibility to develop applications that can be used in domains such as sports and physical rehabilitation.

Quadrupedal galloping control for a wide range of speed via vertical impulse scaling.

PubMed

Park, Hae-Won; Kim, Sangbae

2015-03-25

This paper presents a bio-inspired quadruped controller that allows variable-speed galloping. The controller design is inspired by observations from biological runners. Quadrupedal animals increase the vertical impulse that is generated by ground reaction forces at each stride as running speed increases and the duration of each stance phase reduces, whereas the swing phase stays relatively constant. Inspired by this observation, the presented controller estimates the required vertical impulse at each stride by applying the linear momentum conservation principle in the vertical direction and prescribes the ground reaction forces at each stride. The design process begins with deriving a planar model from the MIT Cheetah 2 robot. A baseline periodic limit cycle is obtained by optimizing ground reaction force profiles and the temporal gait pattern (timing and duration of gait phases). To stabilize the optimized limit cycle, the obtained limit cycle is converted to a state feedback controller by representing the obtained ground reaction force profiles as functions of the state variable, which is monotonically increasing throughout the gait, adding impedance control around the height and pitch trajectories of the obtained limit cycle and introducing a finite state machine and a pattern stabilizer to enforce the optimized gait pattern. The controller that achieves a stable 3 m s(-1) gallop successfully adapts the speed change by scaling the vertical ground reaction force to match the momentum lost by gravity and adding a simple speed controller that controls horizontal speed. Without requiring additional gait optimization processes, the controller achieves galloping at speeds ranging from 3 m s(-1) to 14.9 m s(-1) while respecting the torque limit of the motor used in the MIT Cheetah 2 robot. The robustness of the controller is verified by demonstrating stable running during various disturbances, including 1.49 m step down and 0.18 m step up, as well as random ground height and model parameter variations.

X-Ray Studies of Delphi Diesel Injection Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Christopher

2017-01-01

This CRADA explored the performance of two different models of Delphi diesel injectors. For each injector, the valve needle motion was imaged from two lines of sight at three different injection pressures to characterize its 3D motion. The needle lift was quite repeatable, and followed the expected trend of faster lift with higher injection pressure. In addition, it was observed that the maximum lift increased with injection pressure, even after the valve reached its mechanical limit, indicating that the increased fuel pressure was causing compression or bending of the needle. The off-axis motion of the needle was found to bemore » significant in both measurement planes, though it was very repeatable from one injection event to the next. The effect of ambient pressure on the needle motion was explored at an injection pressure of 400 bar, with ambient pressure up to 15 bar. No effect of the elevated ambient pressure on the needle lift was observed. High-speed x-ray imaging of the spray as it first emerges from the injector nozzle was performed in order to characterize the near-nozzle morphology and breakup of the spray. While imaging was successful at low ambient pressure, the contrast of the images was reduced at high ambient pressures, and quantitative measurements of the morphology were precluded. The near-nozzle fuel distributions were measured using time-resolved x-ray radiography for three injection pressures at an ambient pressure of 33 bar. Increasing injection pressure caused the fuel distribution to narrow, as measured by the Full Width at Half Maximum of the mass distributions. The fuel distributions were quantified for the two injectors at each measurement condition, quantifying the impact that each experimental parameter has on the near-nozzle fuel and air mixture preparation.« less

Influence of centrifugation conditions on the results of 77 routine clinical chemistry analytes using standard vacuum blood collection tubes and the new BD-Barricor tubes

PubMed Central

Cadamuro, Janne; Mrazek, Cornelia; Leichtle, Alexander B.; Kipman, Ulrike; Felder, Thomas K.; Wiedemann, Helmut; Oberkofler, Hannes; Fiedler, Georg M.; Haschke-Becher, Elisabeth

2017-01-01

Introduction Although centrifugation is performed in almost every blood sample, recommendations on duration and g-force are heterogeneous and mostly based on expert opinions. In order to unify this step in a fully automated laboratory, we aimed to evaluate different centrifugation settings and their influence on the results of routine clinical chemistry analytes. Materials and methods We collected blood from 41 healthy volunteers into BD Vacutainer PST II-heparin-gel- (LiHepGel), BD Vacutainer SST II-serum-, and BD Vacutainer Barricor heparin-tubes with a mechanical separator (LiHepBar). Tubes were centrifuged at 2000xg for 10 minutes and 3000xg for 7 and 5 minutes, respectively. Subsequently 60 and 21 clinical chemistry analytes were measured in plasma and serum samples, respectively, using a Roche COBAS instrument. Results High sensitive Troponin T, pregnancy-associated plasma protein A, ß human chorionic gonadotropin and rheumatoid factor had to be excluded from statistical evaluation as many of the respective results were below the measuring range. Except of free haemoglobin (fHb) measurements, no analyte result was altered by the use of shorter centrifugation times at higher g-forces. Comparing LiHepBar to LiHepGel tubes at different centrifugation setting, we found higher lactate-dehydrogenase (LD) (P = 0.003 to < 0.001) and lower bicarbonate values (P = 0.049 to 0.008) in the latter. Conclusions Serum and heparin samples may be centrifuged at higher speed (3000xg) for a shorter amount of time (5 minutes) without alteration of the analytes tested in this study. When using LiHepBar tubes for blood collection, a separate LD reference value might be needed. PMID:29187797

Influence of centrifugation conditions on the results of 77 routine clinical chemistry analytes using standard vacuum blood collection tubes and the new BD-Barricor tubes.

PubMed

Cadamuro, Janne; Mrazek, Cornelia; Leichtle, Alexander B; Kipman, Ulrike; Felder, Thomas K; Wiedemann, Helmut; Oberkofler, Hannes; Fiedler, Georg M; Haschke-Becher, Elisabeth

2018-02-15

Although centrifugation is performed in almost every blood sample, recommendations on duration and g-force are heterogeneous and mostly based on expert opinions. In order to unify this step in a fully automated laboratory, we aimed to evaluate different centrifugation settings and their influence on the results of routine clinical chemistry analytes. We collected blood from 41 healthy volunteers into BD Vacutainer PST II-heparin-gel- (LiHepGel), BD Vacutainer SST II-serum-, and BD Vacutainer Barricor heparin-tubes with a mechanical separator (LiHepBar). Tubes were centrifuged at 2000xg for 10 minutes and 3000xg for 7 and 5 minutes, respectively. Subsequently 60 and 21 clinical chemistry analytes were measured in plasma and serum samples, respectively, using a Roche COBAS instrument. High sensitive Troponin T, pregnancy-associated plasma protein A, ß human chorionic gonadotropin and rheumatoid factor had to be excluded from statistical evaluation as many of the respective results were below the measuring range. Except of free haemoglobin (fHb) measurements, no analyte result was altered by the use of shorter centrifugation times at higher g-forces. Comparing LiHepBar to LiHepGel tubes at different centrifugation setting, we found higher lactate-dehydrogenase (LD) (P = 0.003 to < 0.001) and lower bicarbonate values (P = 0.049 to 0.008) in the latter. Serum and heparin samples may be centrifuged at higher speed (3000xg) for a shorter amount of time (5 minutes) without alteration of the analytes tested in this study. When using LiHepBar tubes for blood collection, a separate LD reference value might be needed.

Application of modified stir bar with nickel:zinc sulphide nanoparticles loaded on activated carbon as a sorbent for preconcentration of losartan and valsartan and their determination by high performance liquid chromatography.

PubMed

Pebdani, Arezou Amiri; Dadfarnia, Shayesteh; Shabani, Ali Mohammad Haji; Khodadoust, Saeid; Haghgoo, Soheila

2016-03-11

In this study, the stir bar was coated for the first time with the ​nicel:zins sulphide nanoparticles (Ni:ZnS NPs) loaded on activated carbon (AC) (Ni:ZnS-AC) as well as 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL) using sol gel technique and was used for stir bar sorptive extraction (SBSE) of losartan (LOS) and valsartan (VAL) as the model compounds. The extracted analytes were then quantified by high performance liquid chromatography (HPLC) equipped with an ultra violet detector. The best extraction performance for LOS and VAL was obtained through the optimization of the parameters affecting SBSE including pH of sample solution, ionic strength, extraction time, volume of desorption solvent, desorption time, and stirring speed. The fractional factorial design (FFD) was used to find the most important parameters, which were then optimized by the central composite design (CCD) and the desirability function (DF). Under the optimal experimental conditions, wide linear ranges of 0.4-50μgL(-1) and 0.5-50μgL(-1) and good RSDs (at level of 5μgL(-1) and n=6) of 4.4 and 4.9% were obtained for LOS and VAL, respectively. With the enrichment factors (EFs) of 188.6 and 184.8-fold, the limits of detection (LODs, S/N=3) of the developed method were found to be 0.12 and 0.15μgL(-1) for LOS and VAL, respectively. The developed method was successfully applied to the determination of LOS and VAL in urine and plasma matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

Women with fibromyalgia walk with an altered muscle synergy.

PubMed

Pierrynowski, Michael R; Tiidus, Peter M; Galea, Victoria

2005-11-01

Most individuals can use different movement and muscle recruitment patterns to perform a stated task but often only one pattern is selected which optimizes an unknown global objective given the individual's neuromusculoskeletal characteristics. Patients with fibromyalgia syndrome (FS), characterized by their chronic pain, reduced physical work capacity and muscular fatigue, could exhibit a different control signature compared to asymptomatic control volunteers (CV). To test this proposal, 22 women with FS, and 11 CV, were assessed in a gait analysis laboratory. Each subject walked repeatedly at self-selected slow, comfortable, and fast walking speeds. The gait analysis provided, for each walk, each subject's stride time, length, and velocity, and ground reaction force, and lower extremity joint kinematics, moments and powers. The data were then anthropometrically scaled and velocity normalized to reduce the influence of subject mass, leg length, and walking speed on the measured gait outcomes. Similarities and differences in the two groups' scaled and normalized gait patterns were then determined. Results show that FS and CV walk with externally similar stride lengths, times, and velocities, and joint angles and ground reaction forces but they use internally different muscle recruitment patterns. Specifically, FS preferentially power gait using their hip flexors instead of their ankle plantarflexors. Interestingly, CV use a similar muscle fatiguing recruitment pattern to walk fast which parallels the common complaint of fatigue reported by FS walking at comfortable speed.

Side scanner for supermarkets: a new scanner design standard

NASA Astrophysics Data System (ADS)

Cheng, Charles K.; Cheng, J. K.

1996-09-01

High speed UPC bar code has become a standard mode of data capture for supermarkets in the US, Europe, and Japan. The influence of the ergonomics community on the design of the scanner is evident. During the past decade the ergonomic issues of cashier in check-outs has led to occupational hand-wrist cumulative trauma disorders, in most cases causing carpal tunnel syndrome, a permanent hand injury. In this paper, the design of a side scanner to resolve the issues is discussed. The complex optical module and the sensor for aforesaid side scanner is described. The ergonomic advantages offer the old counter mounted vertical scanner has been experimentally proved by the industrial funded study at an independent university.

Plasma-Assisted Control of Mach-2 Flowfield over Ramp Geometry

NASA Astrophysics Data System (ADS)

Watanabe, Yasumasa; Leonov, Sergey B.; Houpt, Alec; Hedlund, Brock E.; Elliott, Skye

2017-10-01

This study examined the effect of Reynolds number on plasma-assisted flow control ahead of a compression ramp geometry in Mach-2 supersonic flow. The experiments were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. Stagnation temperature and pressure were varied as T0=294-500K and P0=1-3bar to attain Reynolds number ranging from 3.4×105-2.2×106. Ramp pressure measurements, schlieren visualization, and high-speed camera imaging were used for the evaluation of plasma-assisted flow control effects. A linear dependency was found between the ramp pressure change per averaged plasma power and Reynolds number.

Fluvial responses to the Weichselian ice sheet advances and retreats: implications for understanding river paleohydrology and pattern changes in Central Poland

NASA Astrophysics Data System (ADS)

Weckwerth, Piotr

2018-06-01

The evolution of the fluvial systems during the Weichselian Pleniglacial in the Toruń Basin (Central Poland) was investigated through sedimentological investigation and paleohydraulic analysis. Within the basin, three fluvial cycles deposited after successive phases of the ice advance which took place 50, 28 and 20 ka ago. Successions of four fluvial lithotypes characterize each fluvial formation, that are related to the paleoenvironmental changes (e.g., climate instability and changes in the river regime) which affected the channel hydraulics and morphology. The successions comprise river-style metamorphosis between high-energy sand-bed meandering rivers (lithotype M1), high-energy sand-bed braided rivers (lithotype B1), and medium-energy sand-bed braided rivers with either unit bars (lithotype B2) or compound bars (lithotype B3) reflects the maturity stage of sand-bed-braided river evolution in the basin. The assessment of the fluvial sedimentary environments enabled the construction of a quantitative model of the changes in the river channel pattern in relation to the climate oscillation. Both the paleohydrological controls and their sedimentary consequences are discussed in the article. Lithotypes M1 and B1 represent riverbed modeled under supercritical flow condition. Deposition of lithotype B2 corresponded to the river channel pattern transformation and was manifested by decreasing flow velocity (energy losses associated with bedform roughness and with the transportation of coarser particles). The flow velocity was generally greater in rivers of lithotype B3 and energy of sedimentary environment was more stable than during the deposition of lithotype B2.